Title of Invention

TONER, AND DEVELOPING AGENT, CONTAINER PACKED WITH TONER, PROCESS CARTRIDGE, IMAGE FORMING APPARATUS AND METHOD OF IMAGE FORMING

Abstract To provide a toner that can provide long-term removability and high- definition images with reduced image layer thickness and densely-packed toner particles, a developer capable of forming high-quality images using the toner, a toner container for containing the toner, a process cartridge using the toner, an image forming apparatus using the toner, and an image forming method using the toner. The toner of the present invention is a toner having a substantially spherical shape with irregularities on its surface and containing at least a binder resin and a colorant, wherein a surface factor SF-1 that represents the sphericity of toner particles is 105 to 180, a surface factor SF-2 that represents the degree of surface irregularities of the toner particles is correlated with the volume-average diameter of the toner particles, and the toner particles have an inorganic oxide particle-containing layer within 1 µm from their surfaces.
Full Text DESCRIPTION
Technical Field
The present invention relates to a toner for developing a latent
electrostatic image in electrophotography, electrostatic recording, electrostatic
printing or the like, a developer using the toner, a toner container for
containing the toner, a process cartridge using the toner, an image forming
apparatus using the toner, and an image forming method using the toner.
Background Art
Electrophotography uses a developer to develop a latent electrostatic
image formed on a latent electrostatic image bearing member. Such a
developer can be classified into two types: a one-component developer
consisting of toner, and a two-component developer consisting of carrier and
toner. The two-component developer can provide relatively stable, excellent
images by mixing carrier and toner together to allow toner particles to be
positively or negatively charged.
Toner production process can be broadly divided into two general
categories: dry process, and wet process. In the former process, a binder
resin, a colorant, a releasing agent, etc., are melted and mixed together by heat
and pressure, cooled, and pulverized into toner particles. Since this
pulverization process involves smashing of toner particles into a plate by


means of air pressure and collision of toner particles, finely pulverized toner
particles are not spherical and have irregularities.
In the latter process, a binder resin, a colorant, a releasing agent, etc.,
are added to a solvent for polymerization, followed by drying to produce toner
particles which are therefore spherical and have smooth surfaces.
Along the widespread use of color-image forming apparatus of recent
years, small diameter toners are under study for high-definition color images.
For the production of small diameter toners, wet process is more
advantageous than dry process. Wet process, however, tends to produce
spherical, smooth toner particles as described above, resulting in poor
removability. In particular, cleaning troubles occur frequently in the case of
blade cleaning. Against this background, a number of proposals have been
under study to control toner shape in wet process.
For example, Patent Literature 1 discloses a toner that comprises toner
particles and an external additive and has the following characteristics: average
circularity = 0.920 to 0.995; weight-average particle diameter = 2.0 µm to 9.0
µm; the proportion of particles with an average circularity of less than 0.950 is
2% to 40% on a number basis; and the external additive is present on the toner
particles in the form of primary particles or secondary particles.
Patent Literature 2 discloses a toner composed of toner particles,
where a coefficient of variation for shape coefficient is 16% or less and a
coefficient of number variation in the number-based size distribution is 27% or


less.
Patent Literature 3 discloses a toner that comprises resin particles and
a colorant and satisfies the following conditions at the same time: GSDv ≤
1.25, SF = 125 to 140, D50v = 3 µm to 7 µm, (the proportion of particles with
SF-1 of 120 or less ) ≤ 20% on a number basis, (the proportion of particles
with SF-1 of 150 or greater) ≤ 20% on a number basis, and (the proportion of
particles with SF-1 of 120 or less and a circle equivalent diameter of 4/5 or
less) ≤ 10% on a number basis.
Patent Literature 4 discloses an image forming method using a toner
where a coefficient of variation for shape coefficient is 16% or less, a
coefficient of number variation in the number-based size distribution is 27% or
less, and a toner flocculation ratio is 3% to 35%.
It is, however, difficult for the strategies disclosed in Patent
Literatures 1 to 4 to provide high-definition images and to achieve long-term
stable removability. More specifically, toner particles with specific shape
factors specified by these conventional techniques cannot be removed well
with a blade cleaning approach. Furthermore, there is a problem that cleaning
troubles occur, particularly in a case where smaller toner particle diameters are
employed along with the recent demand for high-quality images and where
toner particles have smooth surfaces without irregularities.
Thus, toners that can provide long-term removability and high-
definition images with reduced image layer thickness and densely-packed toner


particles, and related technologies using such toners have not yet been
provided.
[Patent Literature 1] Japanese Patent Application Laid-Open (JP-A)
No.11-174731
[Patent Literature 2] Japanese Patent Application Laid-Open (JP-A)
No.2000-214629
[Patent Literature 3] Japanese Patent Application Laid-Open (JP-A)
No.2000-267331
[Patent Literature 4] Japanese Patent Application Laid-Open (JP-A)
No.2002-62685
Disclosure of the Invention
It is an object of the present invention to solve the foregoing
conventional problems and to provide a toner that can provide long-term
removability and high-definition images with reduced image layer thickness
and densely-packed toner particles, a developer capable of forming high-
quality images by use of the toner, a toner container for containing the toner, a
process cartridge using the toner, an image forming apparatus using the toner,
and an image forming method using the toner.
The following is the means for solving the foregoing problems:
A toner including: a toner material which comprises a binder
resin and a colorant, wherein the toner has a substantially spherical shape with


irregularities on its surface, and wherein a surface factor SF-1 represented by
the following Equation (1) that represents the sphericity of toner particles is
105 to 180, a surface factor SF-2 represented by the following Equation (2)
that represents the degree of surface irregularities of the toner particles is
correlated with the volume-average diameter of the toner particles, and the
toner particles have an inorganic oxide particle-containing layer within 1 am
from their surfaces.
SF-1 = [(MXLNG)2/AREA] x (100Π/4) ... Equation (1)
where MXLNG represents the maximum length across a two-
dimensional projection of a toner particle, and AREA represents the area of the
projection
SF-2 = [(PERI)2/AREA] x (100/4Π) ... Equation (2)
where PERI represents the perimeter of a two-dimensional projection
of a toner particle, and AREA represents the area of the projection
The toner according to , wherein the SF-1 is 115 to 160 and
the SF-2 is 110 to 300.
The toner according to one of to , wherein the
difference between the SF-2 of toner particles whose particle diameter is
smaller than the most abundant toner particle diameter in a particle size
distribution and the SF-2 of toner particles whose particle diameter is equal to
or larger than the most abundant toner particle diameter in the particle size
distribution is 8 or greater.


The toner according to any one of to , wherein the
inorganic oxide particle-containing layer comprises silica.
The toner according to any one of to , wherein the
volume-average particle diameter is 3 µm to 10 µm.
The toner according to any one of to , wherein the ratio
of the volume-average particle diameter (Dv) to the number-average particle
diameter (Dn), (Dv/Dn), is 1.00 to 1.35.
The toner according to any one of to , wherein the
proportion of toner particles having a circle equivalent diameter, the diameter
of a circle having the same area as the projection of toner particle, of 2 (i,m is
20% or less on a number basis.
The toner according to any one of to , wherein the
porosity of the toner particles under pressure of 10 kg/ cm2 is 60% or less.
The toner according to any one of to , wherein the
toner is produced by emulsifying or dispersing a toner material solution or a
toner material dispersion in an aqueous medium to form toner particles.
The toner according to , wherein the toner material solution
or toner material dispersion comprises an organic solvent, and the organic
solvent is removed upon or after production of toner particles.
The toner according to one of to , wherein the toner
material comprises an active hydrogen group-containing compound and a
polymer capable of reacting with the active hydrogen group-containing


compound, and toner particles are produced by reaction of the active hydrogen
group-containing compound with the polymer to produce an adhesive base
material which the toner particles comprise.
The toner according to , wherein the toner material
comprises an unmodified polyester resin and the mass ratio of the polymer
capable of reacting with the active hydrogen group-containing compound to
the unmodified polyester resin (polymer / unmodified polyester resin) is 5/95
to 80/20.
A developer including a toner according to any one of to
.
The developer according to , wherein the developer is any
one of a one-component developer and a two-component developer.
A toner container including a toner according to any one of
to.
A process cartridge including: a latent electrostatic image
bearing member; and a developing unit configured to develop a latent
electrostatic image formed on the latent electrostatic image bearing member by
use of a toner according to any one of to to form a visible image.
An image forming apparatus including: a latent electrostatic
image bearing member; a latent electrostatic image forming unit configured to
form a latent electrostatic image on the latent electrostatic image bearing
member; a developing unit configured to develop the latent electrostatic image


by use of a toner according to any one of to to form a visible image;
a transferring unit configured to transfer the visible image to a recording
medium; and a fixing unit configured to fix the transferred visible image to the
recording medium.
An image forming method including: forming a latent
electrostatic image on a latent electrostatic image bearing member; developing
the latent electrostatic image by use of a toner according to any one of to
to form a visible image; transferring the visible image to a recording
medium; and fixing the transferred visible image to the recording medium.
The toner of the present invention is a toner that has a substantially
spherical shape with irregularities on its surface and comprises a toner material
which comprises a binder resin and a colorant, wherein a surface factor SF-1
represented by the foregoing Equation (1) that represents the sphericity of
toner particles is 105 to 180, a surface factor SF-2 represented by the foregoing
Equation (2) that represents the degree of surface irregularities of the toner
particles is correlated with the volume-average diameter of the toner particles,
and the toner particles have an inorganic oxide particle-containing layer within
1 µm from their surfaces. Thus, it is possible a toner that can provide long-
term removability and high-definition images with reduced image layer
thickness and densely-packed toner particles.
The developer of the present invention comprises the toner of the
present invention. Thus electrophotographical image formation using this


developer can provide long-term removability and high-definition images with
reduced image layer thickness and densely-packed toner particles, achieving
stable formation of high-quality images with good reproducibility.
The toner container of the present invention contains therein the toner
of the present invention. Thus electrophotographical image formation using
the toner contained the toner container can provide long-term removability and
high-quality images with excellent properties (e.g., charging and transferring
properties).
The process cartridge of the present invention comprises a latent
electrostatic image bearing member and a developing unit configured to
develop a latent electrostatic image formed on the latent electrostatic image
bearing member by use of the toner of the present invention to form a visible
image. The process cartridge can be detachably attached to an image forming
apparatus, features easy-to-handle, and uses the toner of the present invention.
Thus it offers excellent cleanability and excellent toner properties (e.g.,
charging and transferring properties), making it possible to provide high-
quality images.
The image forming apparatus of the present invention comprises: a
latent electrostatic image bearing member; a latent electrostatic image forming
unit configured to form a latent electrostatic image on the latent electrostatic
image bearing member; a developing unit configured to develop the latent
electrostatic image by use of the toner of the present invention to form a


visible image; a transferring unit configured to transfer the visible image to a
recording medium; and a fixing unit configured to fix the transferred visible
image to the recording medium. In the image forming apparatus the latent
electrostatic image forming unit forms a latent electrostatic image on the latent
electrostatic image bearing member, the transferring unit transfers a developed
visible image to a recording medium, and the fixing unit fixes the transferred
visible image to the recording medium. Thus it is possible to form high-
quality electrophotographic images that offer excellent toner removability and
excellent toner properties (e.g., charging and transferring properties).
The image forming method of the present invention comprises the
steps of: forming a latent electrostatic image on a latent electrostatic image
bearing member; developing the latent electrostatic image by use of the toner
of the present invention to form a visible image; transferring the visible image
to a recording medium; and fixing the transferred visible image to the
recording medium. In the latent electrostatic image forming step a latent
electrostatic image is formed on a latent electrostatic image bearing member.
In the transferring step a developed visible image is transferred to a recording
medium. In the fixing step the transferred visible image is fixed to the
recording medium. Thus it is possible to form high-quality
electrophotographic images that offer excellent toner removability and
excellent toner properties (e.g., charging and transferring properties).


Brief Description of the Accompanying Drawings
FIG. 1 is a schematic diagram of a toner particle for explaining the
shape factor SF-1.
FIG. 2 is a schematic diagram of a toner particle for explaining the
shape factor SF-2.
FIG. 3 is a schematic view showing an example of a device for
measuring the porosity of toner particles.
FIG. 4 is a schematic view showing an example of the process
cartridge of the present invention.
FIG. 5 is a schematic view showing an example of carrying out the
image forming method of the present invention by means of the image forming
apparatus of the present invention.
FIG. 6 is a schematic view showing another example of carrying out
the image forming method of the present invention by means of the image
forming apparatus of the present invention.
FIG. 7 is a schematic view showing an example of carrying out the
image forming method of the present invention by means of the image forming
apparatus of the present invention (a tandem color-mage forming apparatus).
FIG. 8 is a partially enlarged schematic view of the image forming
apparatus of FIG. 7.
FIG. 9A is a photograph of toner particles in Example 1 accumulated
on a latent electrostatic image bearing member.


FIG. 9B is a photograph of toner particles in Comparative Example 2
accumulated on a latent electrostatic image bearing member.
Best Mode for Carrying Out the Invention
(Toner)
The toner of the present invention has a substantially spherical shape
with irregularities on the surface, comprises a toner material comprising a
binder resin and a colorant, and further comprises additional ingredient(s) as
needed.
The shape factor SF-1, representing the sphericity of toner particle, of
the toner is 105 to 180, and there is a correlation between the shape factor SF-2
that represents the degree of surface irregularities of toner particles and the
volume-average particle diameter.
The shape of the toner is substantially spherical, including an oval
shape. This enhances the flowability and facilitates its mixing with carrier.
Moreover, unlike irregular toner particles, spherical toner particles are
uniformly charged by friction with carrier and thus show a narrow charge
density distribution, leading to reduced background fogging. Spherical toner
particles can also realize an increased transfer ratio because they are developed
and transferred in strict accordance with electrical field lines.
FIG. 1 is a schematic diagram of a toner particle for explaining the
shape factor SF-1.


The shape factor SF-1 represents the sphericity of toner shape and is
represented by the following Equation (1). SF-1 is a value obtained by
dividing the square of the maximum length (MXLNG) across a two-
dimensional projection of a toner particle by the projection area (AREA) and
by multiplying by 100π/4.
SF-1 = [(MXLNG)2/AREA] x (100π/4) ... Equation (1)
where MXLNG represents the maximum length across a two-
dimensional projection of a toner particle, and AREA represents the area of the
projection
The shape factor SF-1 is 105 to 180, preferably 115 to 160 and more
preferably, 120 to 150.
If the shape factor SF-1 is 100, the toner shape is a perfect sphere; the
greater the shape factor SF-1, the more irregular the toner shape. If the shape
factor SF-1 is greater than 180, removability is improved but the charge
density distribution becomes wide, thereby resulting in increased background
fogging and reduced image quality because the toner shape largely deviates
from sphere. In addition, since developing and transferring of image are not
conducted in strict accordance with magnetic field lines due to air drag upon
transfer, the toner is developed between thin lines to result in reduced image
uniformity and poor image quality. Meanwhile, even when SF-1 is 105 and
thus particles are close to a perfect sphere, toners in which the volume-average
particle diameter is correlated with the shape factor SF-2 can be removed even


with a blade cleaning approach and can provide high-quality images because of
their high image uniformity.
For a toner to be made substantially spherical, in a case of a toner
produced by a dry pulverization process, it is made spherical thermally or
mechanically after pulverization. For a thermal process, for example, toner
particles can be made spherical by spraying them in an atomizer together with
heat flow. For a mechanical process, toner particles can be made spherical by
placing them into a mixer (e.g., a ball mill) for pulverization together with low
specific gravity medium such as glass. Note, however, that such a thermal
process entails aggregation of toner particles to form large particles and thus
requires an additional classifying step for removing them, and that such a
mechanical process entails generation of powder and thus similarly requires an
additional classifying step for removing the powder. In addition, toners
particles produced in an aqueous medium can be so controlled that their shapes
range from spherical to oval, by vigorously agitating the medium in a step for
removing a solvent.
The toner has irregularities on its surface. Such a toner is less
adhesive to a photoconductor compared to a toner with a smooth surface,
thereby increasing its removability.
FIG. 2 is a schematic diagram of a toner particle for explaining the
shape factor SF-2. The degree of surface irregularities of toner particles is
represented by the shape factor SF-2 represented by the following Equation


(2). SF-2 is a value obtained by dividing the square of the perimeter (PERI) of
a two-dimensional projection of a toner particle by the projection area (AREA)
and by multiplying by 100/471.
SF-2 = [(PERI)2/AREA] x (100/4Π) ... Equation (2)
where PERI represents the perimeter of a two-dimensional projection
of a toner particle, and AREA represents the area of the projection
The shape factor SF-2 is 110 to 300, preferably 115 to 200 and more
preferably, 118 to 150.
If SF-2 is 100, it indicates that no irregularities are present on the
surface of toner; the greater the SF-2, the more conspicuous the irregularities.
If SF-2 is greater than 300, removability is improved but the degree of surface
irregularities of toner becomes greater and the charge density distribution
becomes wider, resulting in degraded image quality because of increased
background fogging. If SF-2 is 110 and thus the toner surface is smooth,
toners in which the volume-average particle diameter is correlated with the
shape factor SF-2 can be removed even with a blade cleaning approach and can
provide high-quality images because of their narrow charge density
distributions.
The shape factors SF-1 and SF-2 can be determined by, for example,
using a scanning electron microscope (S-800, manufactured by Hitachi Ltd.) to
take toner particle pictures and analyzing them by an image analyzer
(LUSEX3, manufactured by NIRECO Corp.) using the foregoing Equations (1)


and (2).
In the foregoing toner there the shape factor SF-2 is correlated with
the volume-average particle diameter (Dv). Since both electrophotographic
image uniformity and removability are influenced by toner shape and toner
particle diameter, it is possible to control image uniformity and removability
by correlating the volume-average particle diameter with the shape factor SF-2.
As used herein "correlate" means that the shape factor SF-2 varies
depending on the volume-average particle diameter, meaning one of the
followings relationships: (1) SF-2 increases with increasing volume-average
particle diameter, and (2) SF-2 decreases with increasing volume-average
particle diameter. In view of controlling image uniformity and removability, it
is preferable that the volume-average particle diameter be correlated with the
shape factor SF-2 in such a way that SF-2 increases with increasing volume-
average particle diameter.
An example of the method of correlating the volume-average particle
diameter with the surface factor SF-2 for a toner which has a substantially
spherical shape with irregularities on the surface includes a method of
changing the supply rate of a solvent stripper used in a step for causing toner
surface to contract by adjusting the temperature and/or pressure, in a case
where the toner is produced by dissolution suspension - one of wet processes.
For example, if the volume-average particle diameter is intended to be
correlated with the shape factor SF-2 to a greater extent, temperature and the


like may be adjusted to increase the supply rate of the solvent stripper.
Whether or not the volume-average particle diameter is correlated
with the shape factor SF-2 can be determined by, for example, using a
scanning electron microscope (S-800, manufactured by Hitachi Ltd.) to take
toner particle pictures and analyzing them by an image analyzer (LUSEX3,
manufactured by NIRECO Corp.).
The volume-average particle diameter (Dv) of the toner is preferably 3
am to 10 urn, more preferably 3 µm to 7 µm and most preferably, 3 µm to 6.5
am. The use of toner with a volume-average particle diameter of 10 µm or less
can improve reproductivity of fine lines. However, it is preferable that the
volume-average particle diameter be at least 3 urn because too small volume-
average particle diameter reduces developing property and removability.
Moreover, if the volume-average particle diameter is less than 3 µm, the
number of fine, small diameter toner particles that are less likely to be
developed increases at the surface of carrier or at a developing roller, and thus
the friction and contact between toner particles other than these fine particles
and the developing roller or carrier may be so insufficient that the number of
inversely charged toner particles increases to cause abnormalities such as
background fogging, making it difficult to provide high-quality images.
The particle size distribution of the toner represented in terms of the
ratio of the volume-average particle diameter (Dv) to the number-average
particle diameter (Dn), (Dv/Dn), is preferably 1.00 to 1.35 and more


preferably, 1.00 to 1.15. It is possible to provide a uniform toner charge
density distribution by sharpening the particle size distribution. If (Dv/Dn) is
greater than 1.35, the toner charge density distribution becomes too broad and
the number of inversely charged toner particles increases. For these reasons, it
is difficult to provide high-quality images.
The volume-average particle diameter and the ratio (Dv/Dn) of the
volume average particle diameter to the number-average particle diameter can
be determined by calculating the average of particle diameters of 50,000 toner
particles using a Coulter Counter Multisizer (Beckmann Coulter Inc.) at an
aperture diameter of 50 µm corresponding to the sizes of toner particles to be
measured.
In addition, the difference between the SF-2 of toner particles whose
particle diameter is smaller than the most abundant toner particle diameter in
the particle size distribution (hereinafter may be referred to as "small diameter
SF-2") and the SF-2 of toner particles whose particle diameter is equal to or
larger than the most abundant toner particle diameter in the particle size
distribution (hereinafter may be referred to as "large diameter SF-2"), i.e.,
"large diameter SF-2" minus "small diameter SF-2" is preferably 8 or greater,
more preferably 12 or greater and most preferably, 20 or greater; the upper
limit is preferably less than 50.
The fact that this difference is less than 8 means that toner particles
whose particle diameter is smaller than the most abundant particle diameter in


the particle size distribution and toner particles whose particle diameter is
equal to or larger than the most abundant particle diameter in the particle size
distribution have similar shapes. Thus, it may be difficult to obtain effects
brought about by creating a surface factor gradient. If the difference is greater
than 50, the charge density distribution becomes further broad to cause such
problems as reduced image uniformity, reduced transferring property, and
generation of dropouts in resultant images. In addition, while small diameter
toner particles without irregularities on their surfaces are likely to slip through
a cleaning blade, large diameter toner particles with many irregularities, which
can provide most excellent removability, accumulate at the edge of the
cleaning blade to form a "weir" that can in turn remove small diameter toner
particles.
Note that for "the most abundant particle diameter in the particle size
distribution," the top peak in the number-based particle size distribution is
used.
Toner transfer property is associated with the state of aggregated toner
particles developed on a photoconductor. A regular, flat toner layer can
provide an excellent image without dropouts because both a transfer pressure
and a transfer electric field are uniformly applied to the toner layer. An
irregular toner layer causes dropouts and/or unevenness upon image transfer.
How regular the toner layer to be developed is affected by the uniformity of
the toner charge density distribution and/or the uniformity of toner flowability.


To obtain such uniformity, it is preferable that the toner particles be spherical
and have smooth surfaces. Small diameter toners, in particular, have this
tendency and toner particles with more smooth surfaces are uniformly packed
on a photoconductor with a regular surface, providing excellent transferred
images. Meanwhile, once a densely packed toner layer is exposed to unusual
conditions - a slight increase in transfer pressure as in the case of a transfer
sheet with large irregularities (e.g., rough sheet) and/or microspace discharge
upon transferring — it results in widespread reduction in transfer efficiency in
comparison with irregular toners. Moreover, slight transfer unevenness tend to
become manifest because of excellent average transfer ratio.
Now, it is assumed that toner particles are divided into two categories:
large diameter components, and small diameter components. By creating a
surface factor gradient between them, making the surfaces of the small
diameter components smooth, which the small diameter components have a
profound effect of improving image quality such as fine line-reproducibility
and graininess, and providing large irregularities on the large diameter
components, it is possible to prevent creation of an excessively densely packed
toner layer while increasing the proportion of irregular toner particles in the
toner layer. It is therefore possible to provide excellent toner transfer ratio and
a stable toner layer.
The toner comprises an inorganic oxide particle-containing layer
within 1 µm from its surface. The inorganic oxide particle-containing layer


preferably occupies 60% or more of the perimeter of the toner particle when
viewed end-on, and more preferably 75% or more. Most preferably, it covers
the entire surface of the toner particle; however, it may appear sporadically or
may form multiple layers stacked on top of each other.
It is possible to maintain a controlled toner shape by providing such
an inorganic oxide particle-containing layer. If the inorganic oxide particle-
containing layer is not provided within 1 µm from the toner surface, the
controlled toner shape cannot be maintained. In particular, when the toner is
used over time as a developer mixed and agitated with carrier, the toner shape
undergoes changes due to mechanical stress, resulting in reduced image
uniformity and removability in some cases.
Whether or not an inorganic oxide particle-containing layer is formed
within 1 µm from the toner surface can be determined by observing the cross
section of the toner particle using a transmission electron microscope (TEM).
Examples of inorganic oxide particles include oxides of metals (e.g.,
silicon, aluminum, titanium, zirconium, cerium, iron, and magnesium), silica,
alumina, and titania. Among these, silica, alumina, and titania are preferable,
and silica is most preferable.
An example of a method of providing an inorganic oxide particle-
containing layer within 1 µm from the toner surface is as follows: For
example, when a toner is produced by a process similar to dissolution
suspension - one of wet processes, inorganic oxide particles are previously


added to an organic solvent before dissolving or dispersing a toner material
into the organic solvent.
Preferably, the inorganic oxide particles are added to the toner in an
amount of 0.1 % by mass to 2% by mass. If less than 0.1 % by mass is used, the
effect of inhibiting flocculation of toner particles may be impaired. If greater
than 2% by mass is used, it may result in several problems - toner splashes
between fine lines, contamination inside an image forming apparatus, and wear
and tear on a photoconductor.
It is also preferable to modify the toner surface using a
hydrophobizing agent. Examples of the hydrophobizing agent include
dimethyldichlorosilane, trimethylchlorosilane, methyltrichlorosilane,
allyldimethyldichlorosilane, allylphenyldichlorosilane,
benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, a-
chloroethyltrichlorosilane, p-chloroethyltrichlorosilane,
chloromethyldimethylchlorosilane, chloromethyltrichlorosilane,
hexaphenyldisilazane, and hexatolyldisilazane.
The proportion of toner particles having a circle equivalent diameter
(the diameter of a circle having the same area as the projection of toner
particle) of 2 µm is preferably 20% or less on a number basis and, more
preferably, 10% or less. By doing so it is possible to prevent temporal image
quality reduction due to these fine toner particles.
In fine toner particles with a circle equivalent diameter of 2 µm or


less, the charge density per unit mass (µC/g) is large because of their large
surface area per unit mass, and therefore, they are less likely to be developed
and transferred. In particular, after long time use, such fine toner particles
remains in the development device to reduce the volume-average particle
diameter of toner and firmly sticks to the surface of charging members such as
a magnetic carrier. In this way they undesirably inhibit frictional
electrification of large diameter toner particles (e.g., newly added toner
particles), and toner particles that are insufficiently charged broaden the charge
density distribution and form images affected with background fogging, thus
reducing image quality with time.
The proportion (number%) of toner particles with a given circle
equivalent diameter can be determined using a flow particle image analyzer
(FPIA-2100, manufactured by Sysmex Corp.). More specifically, 1% NaCl
aqueous solution is prepared using primary sodium chloride, and filtrated
through a 0.45 µm pore size filter. To 50-100 ml of this solution is added 0.1-
5 ml of a surfactant (preferably alkylbenzene sulfonate) as a dispersing agent,
followed by addition of 1-10 mg of sample. The mixture is then sonicated for
1 minute using an ultrasonicator to prepare a dispersion with a final particle
concentration of 5,000-15,000/µL for measurement. Measurement is made on
the basis of a circle equivalent diameter - the diameter of a circle having the
same area as the 2D image of a toner particle taken by a CCD camera. In view
of resolution of the CCD camera, measurement data are collected from


particles with a circle equivalent diameter of 0.6 µm or more.
The porosity of toner particles is preferably 60% or less under
pressure of 10 kg/cm2 and more preferably, 55% or less. The lower limit is
preferably 45%. By doing so a regular toner layer with a minimum volume is
developed on a photoconductor, producing an image with reduced image layer
thickness and increased image uniformity. Thus it is possible to provide high-
quality images.
The porosity of toner particles can be measured using, for example, a
porosity measurement device shown in FIG. 3. The porosity measurement
device includes a torque meter 1, a conical rotor 2, a load cell 3, a weight 4, a
piston 5, a sample container 6, a shaker 7, and a lifting stage 8.
The porosity can be measured in the following manner. The sample
container 6 is first charged with a given amount of toner, and attached to the
measurement device. The torque meter 1 is operated to rotate the conical rotor
2, and the rotating conical rotor 2 is placed into toner powder. Prior to actual
measurements, toner powder is placed under pressure of 10 kg/cm2 for
compression. The volume and weight of the compressed toner powder are
measured to calculate its porosity while taking its specific gravity taken into
consideration. In this measurement the smaller the porosity at a given
pressure, the more likely that toner particles are packed, and packed particles
show a regular structure like a closest packed structure. The same holds true
for a developed toner.


The production process and constituent material of the toner of the
present invention are not particularly limited as long as the foregoing
requirements are met, and can be selected from those known in the art; for
example, small diameter toners that are substantially spherical and have
irregularities on their surfaces are preferable. Examples of the toner
production process include the method of pulverization and classifying, and
suspension polymerization, emulsion polymerization and polymer suspension
for forming toner base particles by emulsifying, suspending or flocculating an
oil phase in an aqueous medium.
The pulverization method is one for producing toner base particles by
melting and kneading toner material. Note in this pulverization method that
mechanical impacts may be applied to the resultant toner base particles to
control their shapes so that the average circularity is in a range of 0.97 to 1.00.
In this case, such mechanical impacts are applied to the toner base particles
using, for example, a hybridizer or a mechanofusion machine.
In the suspension polymerization method, a colorant, a releasing
agent, etc., are dispersed in a mixture of an oil-soluble polymerization initiator
and polymerizable monomers, and the resultant monomer mixture is emulsified
and dispersed by emulsification to be described later in an aqueous medium
containing a surfactant, a solid dispersing agent, etc. After a polymerization
reaction to produce toner particles, a wet process may be performed for
attaching inorganic particles to their surfaces. At this point, inorganic particles


are preferably attached after removal of excess surfactant or the like by
washing.
Using some of the following polymerizable monomers it is possible to
introduce functional groups to the resin particle surfaces. Examples of such
polymerizable monomers include acids such as acrylic acid, methacrylic acid,
a-cyanoacrylic acid, a-cyanomethacrylic acid, itaconic acid, crotonic acid,
fumaric acid, maleic acid, and maleic acid anhydride; acrylamide,
methacrylamide, diacetoneacryliamide and methylol derivatives thereof;
acrylates and methacrylates bearing amino groups, such as vinylpyridine,
vinylpyrrolidone, vinylimidazole, ethyleneimine, and dimethylaminoethyl
methacrylate.
Alternatively, functional groups can be introduced by using a
dispersing agent having an acidic group and/or basic group that adsorbs to the
resin particle surface.
In the emulsion polymerization method, a water-soluble
polymerization initiator and polymerizable monomers are emulsified in water
using a surfactant, followed by production of latex by general emulsion
polymerization. Separately, a colorant, a releasing agent, etc. are dispersed in
an aqueous medium to prepare a dispersion, which is then mixed with the
latex. The latex particles are then coagulated to toner particle size, heated, and
fused to one another to produce toner particles. Subsequently, a later
described-wet process may be performed for the attachment of inorganic


particles. Functional groups can be introduced to the resin particle surface by
using monomers similar to those that may be used for the suspension
polymerization of the latex.
In the present invention a toner produced by emulsifying or dispersing
a toner material solution or a toner material dispersion in an aqueous medium
is preferable, because the range of choice of available resins is wide, high low-
temperature fixing property is ensured, toner particles can be readily produced,
and it is easy to control the particle diameter, particle size distribution, and
shape.
The toner material solution is prepared by dissolving the toner
material in a solvent, and the toner material dispersion is prepared by
dispersing the toner material in a solvent.
The toner material comprises an adhesive base material obtained by
reacting together an active hydrogen group-containing compound, a polymer
capable of reacting with the active hydrogen group-containing compound, a
binder resin, a releasing agent, and a colorant. The toner material comprises
additional ingredient(s) such as resin particles and/or a charge controlling
agent on an as-needed basis.
- Adhesive Base Material -
The adhesive base material exhibits adhesion to a recording medium
such as paper, comprises an adhesive polymer produced by reaction of the
active hydrogen group-containing compound with the polymer capable of


reacting with it in the aqueous medium, and may further comprise a binder
resin suitably selected from those known in the art.
The weight-average molecular weight of the adhesive base material is
not particularly limited and can be appropriately determined depending on the
intended use. For example, the weight-average molecular weight is preferably
1,000 or more, more preferably 2,000 to 10,000,000 and most preferably, 3,000
to 1,000,000.
If the weight-average molecular weight is less than 1,000, anti-hot-
offset property may be reduced.
The storage modulus of the adhesive base material is not particularly
limited and can be appropriately determined depending on the intended
purpose. For example, the temperature at which the storage modulus equals to
10,000 dyne/cm2 at a measurement frequency of 20 Hz (i.e., TG') is generally
100°C or more and more preferably, 110°C to 200°C. If TG' is less than
100°C, anti-hot-offset property may be reduced.
The viscosity of the adhesive base material is not particularly limited
and can be appropriately determined depending on the intended purpose. For
example, the temperature at which the viscosity equals to 1,000 poise at a
measurement frequency of 20 Hz (i.e., Tη) is generally 180°C or less and more
preferably, 90°C to 160°C. If Tη is greater than 180°C, low-temperature
fixing property may be reduced.
In order to ensure excellent anti-hot-offset property and excellent low-


temperature fixing property, TG' is preferably larger than Tη, i.e., the
difference between TG' and Tr| (or TG' minus TΗ) is preferably 0°C or
greater, more preferably 10°C or greater and most preferably, 20°C or greater.
Note that the greater the difference, the more preferable.
In addition, in order to ensure excellent anti-hot-offset property and
excellent low-temperature fixing property, (TG' minus TΗ) is preferably in a
range of 0°C to 100°C, more preferably 10°C to 90°C and most preferably,
20°C to 80°C.
The adhesive base material is not particularly limited and can be
suitably determined depending on the intended use; preferred examples
include polyester resins.
The polyester resins are not particularly limited and can be suitably
determined depending on the intended use; preferred examples include urea-
modified polyester resins.
The urea modified polyesters are obtained by reacting, in the aqueous
medium, (B) amines as the active hydrogen-containing compounds with (A)
isocyanate group-containing polyester prepolymers as polymers capable of
reacting with the active hydrogen-containing compounds.
In addition, the urea modified polyesters may include a urethane bond
in addition to a urea bond. The molar ratio of the urea bond to the urethane
bond (urea bond/urethane bond) is not particularly limited and can be
appropriately determined; however, it is preferably in a range of 100/0 to


10/90, more preferably 80/20 to 20/80 and most preferably, 60/40 to 30/70.
When the molar ratio of the urea bond is less than 10, it may result in reduced
hot-offset property.
Preferred specific examples of the urea-modified polyesters are the
following compounds (1)-(10):
(1) A mixture of (i) a urea-modified polyester prepolymer modified
with isophorone diamine, the prepolymer obtained by reacting a
polycondensation product of 2 mole ethylene oxide adduct of bisphenol A and
isophthalic acid with isophorone diisocyanate, and (ii) a polycondensation
product of 2 mole ethylene oxide adduct of bisphenol A and isophtalic acid;
(2) A mixture of (i) a urea-modified polyester prepolymer modified
with isophorone diamine, the prepolymer obtained by reacting a
polycondensation product of 2 mole ethylene oxide adduct of bisphenol A and
isophthalic acid with isophorone diisocyanate, and (ii) a polycondensation
product of 2 mole ethylene oxide adduct of bisphenol A and terephthalic acid;
(3) A mixture of (i) a urea-modified polyester prepolymer modified
with isophorone diamine, the prepolymer obtained by reacting a
polycondensation product of 2 mole ethylene oxide adduct of bisphenol A/2
mole propylene oxide adduct of bisphenol A and terephthalic acid with
isophorone diisocyanate, and (ii) a polycondensation product of 2 mole
ethylene oxide adduct of bisphenol A/2 mole propylene oxide adduct of
bisphenol A and terephthalic acid;


(4) A mixture of (i) a urea-modified polyester prepolymer modified
with isophorone diamine, the prepolymer obtained by reacting a
polycondensation product of 2 mole ethylene oxide adduct of bisphenol A/2
mole propylene oxide adduct of bisphenol A and terephthalic acid with
isophorone diisocyanate, and (ii) a polycondensation product of 2 mole
ethylene oxide adduct of bisphenol A and terephthalic acid;
(5) A mixture of (i) a urea-modified polyester prepolymer modified
with hexamethylenediamine, the prepolymer obtained by reacting a
polycondensation product of 2 mole ethylene oxide adduct of bisphenol A and
terephthalic acid with isophorone diisocyanate, and (ii) a polycondensation
product of 2 mole ethylene oxide adduct of bisphenol A and terephthalic acid;
(6) A mixture of (i) a urea-modified polyester prepolymer modified
with hexamethylenediamine, the prepolymer obtained by reacting a
polycondensation product of 2 mole ethylene oxide adduct of bisphenol A and
terephthalic acid with isophorone diisocyanate, and (ii) a polycondensation
product of 2 mole ethylene oxide adduct of bisphenol A/2 mole propylene
oxide adduct of bisphenol A and terephthalic acid;
(7) A mixture of (i) a urea-modified polyester prepolymer modified
with ethylenediamine, the prepolymer obtained by reacting a polycondensation
product of 2 mole ethylene oxide adduct of bisphenol A and terephthalic acid
with isophorone diisocyanate, and (ii) a polycondensation product of 2 mole
ethylene oxide adduct of bisphenol A and terephthalic acid;


(8) A mixture of (i) a urea-modified polyester prepolymer modified
with hexamethylenediamine, the prepolymer obtained by reacting a
polycondensation product of 2 mole ethylene oxide adduct of bisphenol A and
terephthalic acid with diphenylmethane diisocyanate, and (ii) a
polycondensation product of 2 mole ethylene oxide adduct of bisphenol A and
isophthalic acid;
(9) A mixture of (i) a urea-modified polyester prepolymer modified
with hexamethylenediamine, the prepolymer obtained by reacting a
polycondensation product of 2 mole ethylene oxide adduct of bisphenol A/2
mole propylene oxide adduct of bisphenol A and terephthalic
acid/dodecenylsuccinic anhydride with diphenylmethane diisocyanate, and (ii)
a polycondensation product of 2 mole ethylene oxide adduct of bisphenol A/2
mole propylene oxide adduct of bisphenol A and terephthalic acid; and
(10) A mixture of (i) a urea-modified polyester prepolymer modified
with hexamethylenediamine, the prepolymer obtained by reacting a
polycondensation product of 2 mole ethylene oxide adduct of bisphenol A and
isophthalic acid with toluene diisocyanate, and (ii) a polycondensation product
of b2 mole ethylene oxide adduct of bisphenol A and isophthalic acid.
- Active Hydrogen Group-Containing Compounds -
The active hydrogen group-containing compounds serve as an
extension agent or crosslinking agent when a polymer capable of reacting with
the active hydrogen group-containing compounds undergoes an extension


reaction or crosslinking reaction in the aqueous medium.
The active hydrogen group-containing compound is not particularly
limited and can be appropriately determined depending on the intended
purpose as long as it has an active hydrogen group. For example, when the
polymer capable of reacting with the active hydrogen group-containing
compound is an isocyanate group-containing polyester prepolymer (A), amines
(B) are preferably used because high-molecular weight polymers can be
produced by reaction with the isocyanate group-containing polyester
prepolymer (A) e. g., through extension reaction or crosslinking reaction.
The active hydrogen group is not particularly limited and can be
appropriately determined depending on the intended use; examples include
hydroxyl groups (alcoholic hydroxyl group or phenolic hydroxyl group), amino
groups, carboxyl groups, and mercapto groups. These groups may be used
singly or in combination. Among them, an alcoholic hydroxyl group is
particularly preferable.
The amines (B) are not particularly limited and can be appropriately
determined depending on the intended use; examples include diamines (B1),
polyamines containing three or more amine groups (B2), aminoalcohols (B3),
aminomercaptans (B4), amino acids (B5), and compounds (B6) obtained by
blocking the amino groups of (B1) to (B5).
These amines may be used singly or in combination. Among these,
diamines (B1), and mixtures of diamines (B1) and a small amount of


polyamines (B2) are most preferable.
Examples of the diamines (B1) include aromatic diamines, alicyclic
diamines, and aliphatic diamines. Examples of the aromatic diamines include
phenylenediamine, diethyltoluenediamine, and 4, 4'-diaminodiphenylmethane.
Examples of the alicyclic diamines include 4, 4'-diamino-3, 3'-dimethyl
dicyclohexylmethane, diaminecyclohexane, and isophoronediamine. Examples
of the aliphatic diamines include ethylenediamine, tetramethylenediamine, and
hexamethylenediamine.
Examples of the polyamines containing three or more amine groups
(B2) include diethylenetriamine, and triethylenetetramine.
Examples of the aminoalcohols (B3) include ethanolamine, and
hydroxyethylaniline.
Examples of the amino mercaptans (B4) include
aminoethylmercaptan, and aminopropylmercaptan.
Examples of the amino acids (B5) include aminopropionic acid,
aminocaproic acid.
Examples of the compounds (B6) obtained by blocking the amino
groups of (B1) to (B5) include ketimine compounds obtained from the
foregoing amines (B1) to (B5) and ketones (e.g., acetone, methyl ethyl ketone,
and methyl isobutyl ketone), and oxazolidone compounds.
To terminate a elongation reaction, cross-linking reaction, etc.,
between the active hydrogen group-containing compound and the polymer


capable of reacting it, a reaction terminator can be used. The use of such a
reaction terminator is preferable because the molecular weight of the adhesive
base material can be controlled within a desired range. Examples of the
reaction terminator include monoamines such as diethylamine, dibutylamine,
butylamine and laurylamine, and compounds obtained by blocking these
monoamines, such as ketimine compounds.
For the mixture ratio of the amine (B) to the isocyanate group-
containing polyester prepolymer (A), the equivalent ratio of the isocyanate
group [NCO] in the isocyanate group-containing prepolymer (A) to the amino
group [NHx] in the amine (B) is preferably 1/3 to 3/1, more preferably 1/2 to
2/1 and most preferably, 1/1.5 to 1.5/1.
If the equivalent ratio ([NCO]/[NHx]) is less than 1/3, it may result in
poor low-temperature fixing property. If the equivalent ratio is greater than
3/1, the molecular weight of the urea-modified polyester resin may decrease to
result in poor anti-hot-offset property.
- Polymers Capable of Reacting with Active Hydrogen Group-Containing
Compounds -
The polymers capable of reacting with the active hydrogen group-
containing compounds (hereinafter referred to as "prepolymers" in some cases)
are not particularly limited and can be appropriately selected from resins
known in the art, as long as they at least has a site capable of reacting with the
active hydrogen group-containing compounds. Examples such resins include


polyol resins, polyacrylic resins, polyester resins, epoxy resins, and derivatives
thereof.
These may be used singly or in combination. Among them, polyester
resins are particularly preferable in light of their high-flowability and
transparency upon melted.
In the prepolymers the site capable of reacting with the active
hydrogen group-containing compounds is not particularly limited and can be
appropriately selected from known substituents; examples include isocyanate
group, epoxy group, carboxylic group, and acid chloride group.
These substituents may be included singly or in combination. Among
them, an isocyanate group is particularly preferable.
Among the prepolymers, polyester resins containing groups that can
produce a urea bond, or RMPE, are preferable because the molecular weight of
the high-molecular weight component can be easily controlled, excellent oil-
less low-temperature fixing property can be ensured for dry toners, and in
particular, excellent releasing property and excellent fixing property can be
ensured even when an oil-less fixing device is used.
Examples of the groups that can produce a urea bond include an
isocyanate group.
When the group that can form a urea bond in the polyester resin
RMPE is an isocyanate group, a suitable example of the polyester resin
(RMPE) is the isocyanate group-containing polyester prepolymer (A).


The isocyanate group-containing polyester prepolymer (A) is not
particularly limited and can be appropriately determined depending on the
intended purpose; examples include polycondensation products resulted from
polyols (PO) and polycarboxylic acids (PC), and those obtained by reaction of
the active hydrogen group-containing compounds with polyisocyanates (PIC).
The polyols (PO) are not particularly limited and can be appropriately
determined depending on the intended purpose; examples include diols (DIO),
polyols containing three or more hydroxyl groups (TO), and mixtures of diols
(DIO) and a small amount of (TO). These polyols (PO) may be used singly or
in combination. It is preferable, for example, to use the diols (DIO) alone, or
to use mixtures of diols (DIO) and a small amount of (TO).
Examples of the diols (DIO) include alkylene glycols, alkylene ether
glycols, alicyclic diols, alkylene oxide adducts of alicyclic diols, bisphenols,
and alkylene oxide adducts of bisphenols.
The alkylene glycols preferably have 2 to 12 carbon atoms, and
examples thereof include ethylene glycol, 1, 2-propylene glycol, 1, 3-
propylene glycol, 1, 4-butandiol, and 1, 6-hexanediol. Examples of the
alkylene ether glycols include diethylene glycol, triethylene glycol,
dipropylene glycol, polyethylene glycol, polypropylene glycol, and
polytetramethylene ether glycol. Examples of the alicyclic diols include 1, 4-
cyclohexane dimethanol, and hydrogenated bisphenol A. Examples of the
alkylene oxide adducts of the alicyclic diols include those obtained by adding


In the mixture of the diol (DIO) and the polyol containing three or
more hydroxyl groups (TO), the mass ratio (DIO:TO) of diol (DIO) to polyol
(TO) is preferably 100: 0.01-10 and more preferably, 100:0.01-1.
The polycarboxylic acids (PC) are not particularly limited and can be
appropriately determined depending on the intended purpose; examples include
dicarboxylic acids (DIC), polycarboxylic acids containing three or more
carboxyl groups (TC), and mixtures of the dicarboxylic acids (DIC) and the
polycarboxylic acids (TC).
These polycarboxylic acids may be used singly or in combination. It
is preferable to use dicarboxylic acids (DIC) alone, or to use mixtures of
dicarboxylic acids (DIC) and a small amount of the polycarboxylic acids (TC).
Examples of the dicarboxylic acids include alkylene dicarboxylic
acids, alkenylen dicarboxylic acids, and aromatic dicarboxylic acids.
Examples of the alkylene dicarboxylic acids include succinic acid,
adipic acid, and sebacic acid. For the alkenylen dicarboxylic acids, those
having 4 to 20 carbon atoms are preferable, and examples thereof include
maleic acid, and fumaric acid. For the aromatic dicarboxylic acids, those
having 8 to 20 carbon atoms are preferable, and examples thereof include
phthalic acid, isophthalic acid, terephthalic acid, and naphthalene dicarboxylic
acid.
Among them, alkenylene dicarboxylic acids having 4 to 20 carbon
atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms are


preferable.
For the polycarboxylic acids containing three or more carboxyl groups
(TO), those containing three to eight carboxyl groups and those containing
eight or more carboxyl groups are preferable, and examples thereof include
aromatic polycarboxylic acids.
For the aromatic polycarboxylic acids, those having 9 to 20 carbon
atoms are preferable, and examples thereof include trimellitic acid and
pyromellitic acid.
For the polycarboxylic acids (PC), acid anhydrides obtained from the
dicarboxylic acids (DIC), the polycarboxylic acids containing three or more
carboxyl groups (TC) and mixtures of the dicarboxylic acids (DIC) and the
polycarboxylic acids (TC), or lower alkyl esters may be used. Examples of the
lower alkyl esters include methyl esters, ethyl esters, and isopropyl esters.
In the mixture of the dicarboxylic acid (DIC) and the polycarboxylic
acid containing three or more carboxyl groups (TC), the mass ratio (DIC:TC)
of dicarboxylic acid (DIC) to polycarboxylic acid (TC) is not particularly
limited and can be appropriately determined depending on the intended
purpose. For example, the mass ratio (DIC:TC) in the mixture is preferably
100:0.01-10 and more preferably, 100:0.01-1.
The mixture ratio of the polyols (PO) to the polycarboxylic acids (PC)
in their polycondensation reaction is not particularly limited and can be
appropriately determined depending on the intended purpose, for example, the


equivalent ratio [OH]/[COOH] of hydroxyl group [OH] in the polyol (PO) to
carboxyl group [COOH] in the polycarboxylic acid (PC) is preferably 2/1 to
1/1, more preferably 1.5/1 to 1/1 and most preferably, 1.3/1 to 1.02/1.
The content of the polyol (PO) in the isocyanate group-containing
polyester prepolymer (A) is not particularly limited and can be appropriately
determined depending on the intended purpose. For example, the content is
preferably 0.5% by mass to 40% by mass, more preferably 1% by mass to 30%
by mass and most preferably, 2% by mass to 20% by mass.
If the content of the polyol (PO) in the isocyanate group-containing
polyester prepolymer (A) is less than 0.5% by mass, it may result in poor anti-
hot-offset property and the resultant toner may not have excellent thermal
stability and excellent low-temperature fixing property. If the content is
greater than 40% by mass, it may result in poor low-temperature fixing
property.
The polyisocyanates (PIC) are not particularly limited and can be
appropriately determined depending on the intended purpose; examples include
aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic diisocyanates,
aromatic aliphatic diisocyanates, isocyanurates, phenol derivatives thereof, and
polyisocyanates blocked with oximes or caprolactams.
Examples of the aliphatic polyisocyanates include tetramethylene
diisocyanate, hexamethylene diisocyanate, and 2, 6-diisocyanate methyl
caproate, octamethylene diisocyanate, decamethylene diisocyanate,


dodecamethylene diisocyanate, tetradecamethylene diisocyanate,
trimethylhexane diisocyanates, and tetramethylhexane diisocyanates.
Examples of the alicyclic polyisocyanates include isophorone diisocyanate,
and cyclohexylmethane diisocyanate. Examples of the aromatic diisocyanates
include tolylene diisocyanate, and diphenylmethane diisocyanate, 1, 5-
naphthilene diisocyanate, diphenylene-4, 4'-diisocyanato, 4, 4-diisocyanate-3,
3'-dimethylphenyl, 3-methyldiphenyl methane-4, 4'-diisocyanate, and
diphenyl ether-4, 4'-diisocyanate. Examples of the aromatic aliphatic
diisocyanates include α, α, α', α'-tetramethylxylylene diisocyanate. Examples
of the isocyanurates include tris-isocyanatoalkyl-isocyanurate, and
triisocyanatocycloalkyl-isocyan urates.
These polyisocyanates may be used singly or in combination.
In the reaction between the polyisocyanate and the active hydrogen
group-containing polyester resin (e.g., hydroxyl group-containing polyester
resin), the equivalent ratio [NCO]/[OH] of isocyanate group [NCO] in the
polyisocyanate (PIC) to hydroxyl group [OH] in the hydroxyl group-containing
polyester resin is preferably 5/1 to 1/1, more preferably 4/1 to 1.2/1 and most
preferably, 3/1 to 1.5/1.
If the ratio of isocyanate group [NCO] exceeds 5, it may result in poor
low-temperature fixing property. If the ratio of isocyanate group [NCO] is less
than 1, it may result in poor anti-offset property.
The content of polyisocyanate (PIC) component in the isocyanate


alkylene oxides such as ethylene oxide, propylene oxide, or butylene oxide to
the alicyclic diols. Examples of the bisphenols include bisphenol A, bisphenol
F, and bisphenol S. Examples of the alkylene oxide adducts of the bisphenols
include those obtained by adding alkylene oxides such as ethylene oxide,
propylene oxide, or butylene oxide to the bisphenols.
Among them, alkylene glycols of 2 to 12 carbon atoms, and alkylene
oxide adducts of bisphenols are preferable. Alkylene oxide adducts of
bisphenols, and mixtures of the alkylene oxide adducts of bisphenols and
alkylene glycols of 2 to 12 carbon atoms are most preferable.
For the polyalcohols containing three or more hydroxyl groups (TO),
those containing three to eight hydroxyl groups or those containing eight or
more hydroxyl groups are preferable; examples include polyaliphatic alcohols
containing three or more hydroxyl groups, polyphenols containing three or
more hydroxyl groups, and alkylene oxide adducts of the polyphenols.
Examples of the polyaliphatic alcohols containing three or more
hydroxyl groups include glycerine, trimethylol ethane, trimethylol propane,
pentaerythritol, and sorbitol. Examples of the polyphenols containing three or
more hydroxyl groups include trisphenol PA, phenol novolac, and cresol
novolac. Examples of the alkylene oxide adducts of the polyphenols
containing three or more hydroxyl groups include those obtained by adding
alkylene oxides such as ethylene oxide, propylene oxide, or butylene oxide to
the polyphenols containing three or more hydroxyl groups.


group-containing polyester prepolymer (A) is not particularly limited and can
be appropriately determined depending on the intended purpose, for example,
it is preferably 0.5% by mass to 40% by mass, more preferably 1% by mass to
30% by mass and most preferably, 2% by mass to 20% by mass.
If the content is less than 0.5% by mass, it may result in poor anti-hot-
offset property and it may be difficult for the resultant toner to have excellent
thermal stability and excellent low-temperature fixing property. If the content
is greater than 40% by mass, it may result in poor low-temperature fixing
property.
The average number of isocyanate groups contained in per molecule
of the isocyanate-group containing polyester prepolymer (A) is preferably one
or more, more preferably 1.2 to 5 and most preferably, 1.5 to 4.
If the average number of isocyanate groups per molecule is less than
1, the molecular weight of the polyester resin modified by the group for
producing a urea bond (RMPE) may decrease to result in poor anti-hot-offset
property.
The weight-average molecular weight (Mw) of the polymer capable of
reacting with the active hydrogen group-containing compound is preferably
1,000 to 30,000 and more preferably, 1,500 to 15,000, as determined by gel
permeation chromatography (GPC) on the basis of the molecular weight
distribution of polymer dissolved in tetrahydrofuran (THF). If the weight-
average molecular weight (Mw) of the polymer is less than 1,000, it may result


in poor thermal stability of toner, and if the weight-average molecular weight
(Mw) of the polymer is greater than 30,000, it may result in poor low-
temperature fixing property.
Determination of the molecular weight distribution by GPC can be
carried out in the following procedure, for example.
A column is first equilibrated in a heat chamber of 40°C. At this
temperature tetrahydrofuran (THF), a column solvent, is passed through the
column at a flow rate of 1 ml/min, and a sample solution containing a
concentration of 0.05-0.6% by mass of resin in tetrahydrofuran is prepared,
and 50-200 µl of the sample solution is passed through the column. Upon
determination of the sample molecular weight, a molecular weight calibration
curve constructed from several monodisperse polystyrene standards is used to
obtain a molecular weight distribution of the sample solution on the basis of
the relationship between logarithm values of the curve and count values. For
the polystyrene standards for the calibration curve, those with a molecular
weight of 6 x 10 2.1 x 102, 4x 102, 1.75 x 104, 1.1 x 105, 3.9 x 105, 8.6 x 105, 2
x 106, and 4.48 x 106 (produced by Pressure Chemical Corp. or Toyo Soda
Manufacturing Co., Ltd.) are preferably used. It is also preferable to use at
least 10 different polystyrene standards. For a detector, a refractive index (RI)
detector is used.
- Binder Resin -
The binder resin is not particularly limited and can be appropriately


determined depending on the intended purpose; examples include polyesters.
Of these, unmodified polyester resins (i.e., polyester resins that arc not
modified) are particularly preferable.
The addition of such an unmodified polyester resin in toner leads to
improved low-temperature fixing properties and makes image glossy.
Examples of the unmodified polyester resins include resins identical
to the foregoing polyester resins containing a group that produces a urea bond
(RMPE), i.e., polycondensation products of polyols (PO) and polycarboxylic
acids (PC). In view of low-temperature fixing properties and hot-offset
property, a part of the unmodified polyester resin is preferably compatible with
the polyester resin containing a group that produces a urea bond (RMPE), i.e.,
the unmodified polyester resins and the polyester resins (RMPE) preferably
share a similar structure that allow them to be compatible.
The weight-average molecular weight (Mw) of the unmodified
polyester resin is preferably 1,000 to 30,000 and more preferably, 1,500 to
15,000 as determined by gel permeation chromatography (GPC) on the basis of
the molecular weight distribution of polymer dissolved in tetrahydrofuran
(THF).
If the weight-average molecular weight (Mw) of the unmodified
polyester resin is less than 1,000, it may result in poor thermal stability of
toner. Therefore, it is required that the content of an unmodified polyester
resin with a weight-average molecular weight of less than 1,000 be 8% by


mass to 28% by mass. If the weight-average molecular weight (Mw) of the
unmodified polyester resin is greater than 30,000, it may result in poor low-
temperature fixing property.
The glass transition temperature of the unmodified polyester resins is
generally 30°C to 70°C, preferably 35°C to 70°C, more preferably 35°C to
70°C and most preferably, 35°C to 45°C. If the glass transition temperature is
below 30°C, it may result in poor thermal stability of toner. If the glass
transition temperature is above 70°C, it may result in insufficient lower-
temperature fixing property.
The hydroxyl value of the unmodified polyesters is preferably 5 mg
KOH/g or more, more preferably 10 mg KOH/g to 120 mg KOH/g and most
preferably, 20 mg KOH/g to 80 mg KOH/g. If the hydroxyl value is less than
5 mg KOH/g, it may difficult for the resultant toner to achieve excellent
thermal stability and excellent low-temperature fixing property.
The acid value of the unmodified polyester resins is preferably 1.0 mg
KOH/g to 50.0 mg KOH/g, more preferably 1.0 mg KOH/g to 45.0 mg KOH/g
and most preferably, 15.0 mg KOH/g to 45.0 mg KOH/g. In general, toner
having an acid value can be readily charged negatively.
When the unmodified polyester resin is contained in the toner
material, in the mixture, the mass ratio of the polymer capable of reacting with
the active hydrogen group-containing compounds (e.g., a polyester resin
containing a group that produces a urea bond) to the unmodified-polyester


resin is preferably 5/95 to 80/20 and more preferably, 10/90 to 25/75.
If the mass ratio of the unmodified polyester resin (PE) exceeds 95 in
the mixture, anti-hot-offset property may be reduced and it may difficult for
the resultant toner to achieve excellent thermal stability and excellent low-
temperature fixing property. If the mass ratio of the unmodified polyester is
less than 20, mage glossiness may be reduced.
The content of the unmodified polyester resin in the binder resin is
preferably 50% by mass to 100% by mass, more preferably 75% by mass to
95% by mass and most preferably, 80% by mass to 90% by mass, for example.
If the content is less than 50% by mass, it may result in poor low-temperature
fixing property and/or image glossiness may be reduced.
- Colorant -
The colorant is not particularly limited and can be appropriately
selected from known dyes and pigments accordingly. Examples include
carbon black, nigrosine dyes, iron black, Naphthol Yellow S, Hansa Yellow
(10G, 5G, G), cadmium yellow, yellow iron oxide, yellow ocher, chrome
yellow, Titan Yellow, Polyazo Yellow, Oil Yellow, Hansa Yellow (GR, A,
RN, R), Pigment Yellow L, Benzidine Yellow (G, GR), Permanent Yellow
(NCG), Vulcan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake,
anthracene yellow BGL, isoindolinone yellow, colcothar, red lead oxide, lead
red, cadmium red, cadmium mercury red, antimony red, Permanent Red 4R,
Para Red, Fire Red, parachlororthonitroaniline red, Lithol Fast Scarlet G,


Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL,
FRLL, F4RH), Fast Scarlet VD, Vulcan Fast Rubine B, Brilliant Scarlet G,
Lithol Rubine GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet
3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio
Bordeaux BL, Bordeaux 10B, BON Maroon Light, BON Maroon Medium,
eosine lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarine Lake,
Thioindigo Red B, Thioindigo Maroon, Oil Red, quinacridone red, Pyrazolone
Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perynone Orange,
Oil Orange, cobalt blue, cerulean blue, Alkali Blue Lake, Peacock Blue Lake,
Victoria Blue Lake, metal-free phthalocyanine blue, Phthalocyanine Blue, Fast
Sky Blue, Indanthrene Blue (RS, BC), indigo, ultramarine, Prussian blue,
Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, cobalt violet,
manganese violet, dioxazine violet, Anthraquinone Violet, chrome green, zinc
green, chromium oxide, viridian, emerald green, Pigment Green B, Naphthol
Green B, Green Gold, Acid Green Lake, Malachite Green Lake,
Phthalocyanine Green, Anthraquinone Green, titanium oxide, zinc white, and
lithopone.
These may be used singly or in combination.
The content of the colorant in the toner is not particularly limited and
can be appropriately determined depending on the intended purpose; however,
it is preferably 1% by mass to 15% by mass and more preferably, 3% by mass
to 10% by mass.


If the content of the colorant is less than 1 % by mass, the tinting
power of the toner may degrade. If the content of the colorant is greater than
15% by mass, abnormal pigment dispersion occurs in toner, and it may reduce
the tinting power and electric characteristics of toner.
The colorants may be used as a master batch combined with resin.
The resin is not particularly limited and can be appropriately selected from
those known in the art; examples include polymers of styrene or substituted
styrene, styrene copolymers, polymethyl methacrylates, polybutyl
methacrylates, polyvinyl chlorides, polyvinyl acetates, polyethylenes,
polypropylenes, polyesters, epoxy resins, epoxy polyol resins, polyurethanes,
polyamides, polyvinyl butyrals, polyacrylic resins, rosins, modified rosins,
terpene resins, aliphatic hydrocarbon resins, alicyclic hydrocarbon resins,
aromatic petroleum resins, chlorinated paraffins, and paraffins. These resins
may be used singly or in combination.
Examples of the polymers of styrene or substituted styrene include
polyester resins, polystyrenes, poly-p-chlorostyrenes, and polyvinyl toluenes.
Examples of the styrene copolymers include styrene-p-chlorostyrene
copolymers, styrene-propylene copolymers, styrene-vinyltoluene copolymers,
styrene-vinylnahthalene copolymers, styrene-methyl acrylate copolymers,
styrene-ethyl acrylate copolymers, styrene-butyl acrylate copolymers, styrene-
octyl acrylate copolymers, styrene-methyl methacrylate copolymers, styrene-
ethyl methacrylate copolymers, styrene-butyl methacrylate copolymers,


styrene-α-methyl chloromethacrylate copolymer, styrene-acrylonitrile
copolymers, styrene-vinylmethyl-keton copolymers, styrene-butadiene
copolymers, styrene-isoprene copolymers, styrene-acrylonitrile-indene
copolymers, styrene-maleic acid copolymers, and styrene-ester maleate
copolymers.
The master batch may be produced by mixing or kneading the master
batch resin with the colorant while applying a high shearing force. Here, for
increased interaction between the colorant and resin, an organic solvent may be
added thereto. Alternatively, a so-called flashing process is preferably used,
because in the flashing process a colorant wet cake can be used as it is without
drying. The flashing process is a process in which an aqueous paste of
colorant is mixed and kneaded with resin together with an organic solvent to
thereby transfer the colorant to the resin side for removable of moisture and the
organic solvent. For the mixing and kneading, a high shearing dispersion
device (e.g., a triple roll mill) is preferably used.
- Additional ingredients -
The additional ingredients are not particularly limited and can be
appropriately determined depending on the intended purpose; examples include
a releasing agent, charge controlling agent, inorganic particles, cleaning
improver, magnetic material, and metallic soap.
The releasing agent is not particularly limited and can be
appropriately selected from those known in the art; suitable examples include


waxes.
Examples of such waxes include long-chain hydrocarbons, carbonyl
group-containing waxes, and polyolefin waxes. These waxes may be used
singly or in combination. Among them, carbonyl group-containing waxes are
preferable.
Examples of the carbonyl group-containing waxes include
polyalkanoic acid esters, polyalkanol esters, polyalkanoic acid amides,
polyalkyl amides, and dialkyl ketones. Examples of the polyalkanoic acid
esters include carnauba wax, montan wax, trimethylolpropane tribehenate,
pentaerythritol tetrahehenate, pentaerythritol diacetate dibehenate, glycerin
tribehenate, and 1,18-octadecandiol distearate. Examples of the polyalkanol
esters include trimellitic tristearate, and distearyl maleate. Examples of the
polyalkanoic acid amide include behenyl amides. Examples of the polyalkyl
amide include trimellitic acid tristearyl amide. Examples of the dialkyl
ketones include distearyl ketone. Of these carbonyl group-containing waxes,
polyalkanoic esters are most preferable.
Examples of the polyolefin waxes include polyethylene waxes, and
polypropylene waxes.
Examples of the long-chain hydrocarbons include paraffin waxes, and
Sasol Wax.
The melting point of the releasing agent is not particularly limited and
can be appropriately determined depending on the intended purpose; it is


preferably 40°C to 160°C, more preferably 50°C to 120°C and most preferably,
60°C to 90°C.
If the melting point of the releasing agent is below 40°C, the wax may
impair thermal stability of toner. If the melting point of the releasing agent is
below 160°C, cold-off set may occur upon low-temperature fixing.
The melt viscosity of the releasing agent is preferably 5 cps to 1,000
cps and more preferably, 10 cps to 100 cps when measured at a temperature
higher than the melting point of the releasing agent by 20°C.
If the melt viscosity of the releasing agent is less than 5 cps, it may
result in poor releasing property. If the melt viscosity of the releasing agent is
greater than 1,000 cps, it may result in poor anti-hot-offset property and low-
temperature fixing property.
The content of the releasing agent in the toner is not particularly
limited and can be appropriately determined depending on the intended
purpose; it is preferably 0% by mass to 40% by mass and more preferably, 3%
by mass to 30% by mass.
If the content of the releasing agent is greater than 40% by mass, toner
flowability may be reduced.
The charge controlling agent is not particularly limited and can be
appropriately selected from those known in the art. However, when a colored
material is used for the charge controlling agent, toner may show different
tones of color; therefore, colorless materials or materials close to white are


preferably used. Examples include, triphenylmethane dyes, molybdic acid
chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts
(including fluoride-modified quaternary ammonium salts), alkylamides,
phosphous or compounds thereof, tungsten or compounds thereof, fluoride
activators, metal salts of salicylic acid, and metal salts of salicylic acid
derivatives. These may be used singly or in combination.
For the charge controlling agent, commercially available products
may be used; examples include Bontron P-51, a quaternary ammonium salt,
Bontron E-82, an oxynaphthoic acid metal complex, Bontron E-84, a salicylic
acid metal complex, and Bontron E-89, a phenol condensate (produced by
Orient Chemical Industries, Ltd.); TP-302 and TP-415, both are a quaternary
ammonium salt molybdenum metal complex (produced by Hodogaya Chemical
Co.); Copy Charge PSY VP2038, a quaternary ammonium salt, Copy Blue PR,
a triphenylmethane derivative, and Copy Charge NEG VP2036 and Copy
Charge NX VP434, both are a quaternary ammonium salt (produced by
Hoechst Ltd.); LRA-901, and LR-147, a boron metal complex (produced by
Japan Carlit Co., Ltd.); quinacridones; azo pigments; and high-molecular
weight compounds bearing a functional group (e.g., sulfonic group and
carboxyl group).
The charge controlling agent may be melted and kneaded with the
master batch prior to dissolution or dispersion. Alternatively, the charge
controlling agent may be dissolved or dispersed in the organic solvent together


with the foregoing toner ingredients or may be attached to resultant toner
particles.
The proper content of the charge controlling agent in the toner varies
depending on the type of the binder resin, presence of an additive, the method
of dispersion, etc. However, it is preferably present in the toner in an amount
of 0.1 part by mass to 10 parts by mass per 100 parts by mass of the binder
resin and, more preferably, 0.2 part by mass to 5 parts by mass. If less than 0.1
part by mass is used, it may be difficult to control the amount of charge. If
greater than 10 parts by mass is used, toner is so excessively charged that the
effects of the controlling agent are reduced, causing the toner to be firmly
attracted to a developing roller by electrostatic attraction force. For these
reasons, developer flowability may be reduced and/or image density may be
reduced.
- Resin Particles -
The resin particles are not particularly limited and can be
appropriately selected from resins known in the art as long as the resin
particles are capable of forming an aqueous dispersion in an aqueous medium;
it may be either thermoplastic resin or thermosetting resin, and examples
include vinyl resins, polyurethane resins, epoxy resins, polyester resins,
polyamide resin, polyimide resins, silicone resins, phenol resins, melamine
resins, urea resins, anilline resins, ionomer resins, and polycarbonate resins.
Among these, vinyl resins are preferable.


These may be used singly or in combination. The resin particles are
preferably formed of one resin selected from the vinyl resins, polyurethane
resins, epoxy resins, and polyester resins in view of easy production of an
aqueous dispersion containing fine and spherical resin particles.
The vinyl resins are homopolymers or copolymers of vinyl monomers.
Examples include styrene-(meth)acrylic ester resins, styrene-butadiene 1
copolymers, (meth)acrylic acid-acrylic ester copolymers, styrene-acrylonitrile
copolymers, styrene-maleic anhydride copolymers, and styrene-(meth)acrylic
acid copolymers.
In addition, copolymers containing monomers that have at least two
unsaturated groups can also be used for the formation of the resin particles.
The monomer that contains at least two unsaturated groups is not
particularly limited and can be appropriately determined depending on the
intended purpose; examples include a sodium salt of sulfuric acid ester of
ethylene oxide adduct of methacrylic acid (Eleminol RS-30, produced by
Sanyo Chemical Industries Co.), divinylbenzene, and 1,6-hexanediol acrylate.
The resin particles are formed by polymerization of the foregoing
monomers in accordance with a conventional method appropriately selected.
The resin particles are preferably produced in an aqueous dispersion.
Examples of the method for preparing such an aqueous dispersion containing
the resin particles are the following (1) to (8): (1) in a case of the foregoing
vinyl resin, vinyl monomers as a starting material are polymerized by


suspension polymerization, emulsification polymerization, seed
polymerization, or dispersion polymerization to directly prepare an aqueous
dispersion of resin particles; (2) in a case of resin obtained by polyaddition or
polycondensation reaction (e.g., the foregoing polyester resin, polyurethane
resin, or epoxy resin), a precursor (monomers, oligomers or the like) or a
solution containing the precursor is dispersed in an aqueous medium in the
presence of an appropriate dispersing agent, and is heated or added with a
curing agent for curing to prepare an aqueous dispersion of resin particles; (3)
in a case of resin obtained by polyaddition or polycondensation reaction (e.g.,
the foregoing polyester resin, polyurethane resin, or epoxy resin), an
appropriately selected emulsifier is dissolved in a precursor (monomer,
oligomer or the like) or in a solution containing the precursor (preferably a
liquid solution; it may be liquefied by heat), followed by addition of water to
induce phase inversion emulsification to prepare an aqueous dispersion of resin
particles; (4) resin that has previously been prepared by polymerization
(addition polymerization, ring-opening polymerization, polyaddition, addition
condensation, or condensation polymerization) is pulverized in a blade-type or
jet-type pulverizer, the resultant resin powder is classified to produce resin
particles, and the resin particles are dispersed in an aqueous medium in the
presence of an appropriately selected dispersing agent to prepare an aqueous
dispersion of the resin particles; (5) resin that has previously been prepared by
polymerization (addition polymerization, ring-opening polymerization,


polyaddition, addition condensation, or condensation polymerization) is
dissolved in a solvent to prepare a resin solution, the resin solution is sprayed
in the form of mist to produce resin particles, and the resultant resin particles
are dispersed in an aqueous medium in the presence of an appropriately
selected dispersing agent to prepare an aqueous dispersion of the resin
particles; (6) resin that has previously been prepared by polymerization
(addition polymerization, ring-opening polymerization, polyaddition, addition
condensation, or condensation polymerization) is dissolved in a solvent to
prepare a resin solution, resin particles are precipitated by the addition of a
poor solvent or by cooling the resin solution, the solvent is removed to recover
the resin particles, and the resin particles thus obtained are dispersed in an
aqueous medium in the presence of an appropriately selected dispersing agent
to prepare an aqueous dispersion of the resin particles; (7) resin that has
previously been prepared by polymerization (addition polymerization, ring-
opening polymerization, polyaddition, addition condensation, or condensation
polymerization) is dissolved in a solvent to prepare a resin solution, the resin
solution is dispersed in an aqueous medium in the presence of an appropriately
selected dispersing agent, and the solvent is removed by heating or vacuum to
prepare an aqueous dispersion of the resin particles; and (8) resin that has
previously been prepared by polymerization (addition polymerization, ring-
opening polymerization, polyaddition, addition condensation, or condensation
polymerization) is dissolved in a solvent to prepare a resin solution, an


appropriately selected emulsifier is dissolved in the resin solution, and water is
added to the resin solution to induce phase inversion emulsification to thereby
prepare an aqueous dispersion of resin particles.
Examples of the toner include those produced by known suspension
polymerization, emulsion aggregation, or emulsion dispersion. Toners
prepared in the following procedure are also preferable: A toner material
containing an active hydrogen group-containing compound and a polymer
capable of reacting with the compound is dissolved in an organic solvent to
prepare a toner solution, the toner solution is dispersed in an aqueous medium
to prepare a dispersion, where the active hydrogen group-containing compound
is allowed to react with the polymer to produce a particulate adhesive base
material, and the organic solvent is removed to prepare toner particles.
— Toner Solution —
The preparation of the toner solution is carried out by dissolving the
toner material in the organic solvent.
- Organic Solvent -
The organic solvent is not particularly limited and can be
appropriately determined depending on the intended purpose, as long as it is a
solvent capable of dissolving and dispersing the toner material. The
organic solvent is preferably selected from volatile organic solvents with a
boiling point of less than 150°C because they can be readily removed;
examples include toluene, xylene, benzene, carbon tetrachloride, methylene


chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene,
chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl
acetate, methyl ethyl ketone, and methyl isobutyl ketone. Among these
organic solvents, toluene, xylene, benzene, methylene chloride, 1,2-
dichloroethane, chloroform, carbon tetrachloride and the like are preferable,
and ethyl acetate is most preferable. These organic solvents may be used
singly or in combination.
The added amount of the organic solvent is not particularly limited
and can be appropriately determined depending on the intended purpose. It is
preferably added in an amount of 40 parts by mass to 300 parts by mass per
100 parts by mass of the toner material, more preferably 60 parts by mass to
140 parts by mass and, most preferably, 80 parts by mass to 120 parts by mass.
- Dispersion -
The preparation of the dispersion is carried out by dispersing the toner
solution in an aqueous medium.
When the toner solution is dispersed in the aqueous medium, solid
dispersions (oil droplets) derived from the toner solution are formed in the
aqueous medium.
- Aqueous Medium -
The aqueous medium is not particularly limited and can be
appropriately selected from those known in the art; examples include water,
water-miscible solvents, and mixtures thereof. Among them, water is most


preferable.
The water-miscible solvents are not particularly limited as long as
they are miscible in water, and examples include alcohols, dimethylformamide,
tetrahydrofurans, cellosolves, and lower ketones.
Examples of the alcohols include methanol, isopropanol, and ethylene
glycol. Examples of the lower ketones include acetone, and methyl ethyl
ketone.
These organic solvents may be used singly or in combination.
The toner solution is preferably dispersed in the aqueous medium with
agitation.
The method of dispersing is not particularly limited and a known
dispersing device can be used. Examples of such a dispersing device include a
low-speed shearing dispersing device, a high-speed shearing dispersing device,
a friction-type dispersing device, a high-pressure jet dispersing device, and an
ultrasonic dispersing device. Among these, a high-speed shearing dispersing
device is preferable because it is possible to set the diameter of the solid
dispersion (oil droplets) to 2 µm to 20 µm.
When a high-speed shearing dispersing device is used, the rotational
speed, dispersing time, dispersing temperature, etc., are not particularly limited
and can be appropriately set according to the intended purpose. For example,
the rotational speed is preferably 1,000 rpm to 30,000 rpm and, more
preferably, 5,000 rpm to 20,000 rpm. In a case of a batch-type dispersing


device, the dispersing time is preferably 0.1 to 5 minutes, and the dispersing
temperature is preferably 0°C to 150°C and, more preferably, 40°C to 98°C.
Note that in general, the higher the dispersing temperature, the easier it is to
disperse.
As an example of the toner production process, a toner production
process will be described in which a particulate adhesive base material is
produced to obtain toner.
In this process an aqueous medium phase, the toner solution and the
dispersion are prepared, the aqueous medium is added, and other steps (e.g.,
synthesis of a prepolymer capable of reacting with the active hydrogen group-
containing compounds, and synthesis of these active hydrogen group-
containing compounds) are performed.
The preparation of the aqueous medium phase can be carried out by
dispersing the resin particles in the aqueous medium. The content of the resin
particles in the aqueous medium is not particularly limited and can be
appropriately determined depending on the intended purpose; for example, it is
preferably present in an amount of 0.5% by mass to 10% by mass.
The preparation of the toner solution can be carried out by dissolving
or dispersing toner materials - the active hydrogen group-containing
compound, polymer capable of reacting with the compound, colorant, charge
controlling agent, unmodified polyester resin, etc. - in the organic solvent. In
addition, inorganic oxide particles such as silica or titania can be added to the


organic solvent in order to form an inorganic oxide particle-containing layer
within 1 µm from the toner surface.
Among the toner materials, ingredients other than the prepolymer (or
polymer capable of reacting with the active hydrogen group-containing
compound) may be added to the organic solvent at the time when the resin
particles are dispersed therein, or may be added to the aqueous medium phase
at the time when the toner solution is added thereto.
The preparation of the dispersion can be carried out by emulsifying or
dispersing the toner solution in the aqueous medium phase. Causing both the
active hydrogen group-containing compound and the polymer capable of
reacting with this compound to undergo extension or crosslinking reaction
leads to formation of the adhesive base material.
For example, the adhesive base material (e.g. the urea-modified
polyester) may be produced in any one of the following manner (1) to (3): (1)
the toner solution containing the polymer capable of reacting with the active
hydrogen group-containing compound (e.g., the isocyanate group-containing
polyester prepolymer (A)) is emulsified or dispersed in the aqueous medium
phase together with the active hydrogen group-containing compound to form
solid dispersions, allowing the active hydrogen group-containing compound
and the polymer capable of reacting with the active hydrogen group-containing
compound to undergo extension or crosslinking reaction in the aqueous
medium phase; (2) the toner solution is emulsified or dispersed in the aqueous


medium in which the active hydrogen group-containing compound has been
previously added, forming the solid dispersions, and then the active hydrogen
group-containing compound and the polymer capable of reacting with this
compound are allowed to undergo extension or crosslinking reaction in the
aqueous medium phase; and (3) after adding the toner solution to the aqueous
medium phase followed by mixing, the active hydrogen group-containing
compound is added thereto to form solid dispersions, and then the active
hydrogen group-containing compound and the polymer capable of reacting
with this compound are allowed to undergo extension or crosslinking reaction
at particle interfaces in the aqueous medium phase. In the case of procedure
(3), it should be noted that modified polyester resin is preferentially formed on
the surfaces of toner particles, allowing generation of a concentration gradient
in the toner particles.
Reaction conditions under which the adhesive base material is
produced by emulsification or dispersion are not particularly limited and can
be appropriately set according to the combination of the active hydrogen
group-containing compound with the polymer capable of reacting with it. The
reaction time is preferably 10 minutes to 40 hours and, more preferably, 2
hours to 24 hours. The reaction temperature is preferably 0°C to 150°C and,
more preferably, 40°C to 98°C.
A suitable example of the method for stably forming in the aqueous
medium phase the solid dispersions that contain the active hydrogen group-


containing compound and a polymer capable of reacting with this compound
(e.g., the isocyanate group-containing polyester prepolymer (A)) is as follows:
the toner solution in which toner materials such as a polymer capable of
reacting with the active hydrogen group-containing compound (e.g., the
isocyanate group-containing polyester prepolymer (A)), colorant, charge
controlling agent, unmodified polyester resin, etc., are dissolved or dispersed
in the organic solvent is added to the aqueous medium phase, and is dispersed
by application of shearing force. Note that description for the method of
dispersing is similar to that given above.
Upon preparation of the dispersion, a dispersing agent is preferably
used where necessary in order to stabilize the solid dispersions (oil droplets
derived from the toner solution), to obtain a desired particle shape, and to
sharpen the particle size distribution.
The dispersing agent is not particularly limited and can be
appropriately determined depending on the intended purpose. Suitable
examples include surfactants, water-insoluble inorganic dispersing agents, and
polymeric protective colloids. These dispersing agents may be used singly or
in combination.
Examples of the surfactants include anionic surfactants, cationic
surfactants, nonionic surfactants, and ampholytic surfactants.
Examples of the anionic surfactants include alkylbenzene sulfonic
acid salts, α-olefin sulfonic acid salts, and phosphoric acid esters. Among


these, those having a fluoroalkyl group are preferable.
Examples of the anionic surfactants having a fluoroalkyl group
include fluoroalkyl carboxylic acids of 2-10 carbon atoms or metal salts
thereof, disodium perfluorooctanesulfonylglutamate, sodium-3-{omega-(C6-
C11)fluoroalkyloxy}-1-(C3-C4)alkyl sulfonates, sodium-3-{omega-(C6-
C8)fluoroalkanoyl-N-ethylamino}-1 -propanesulfonates, (C11 -C20)fluoroalkyl
carboxylic acids or metal salts thereof, (C7-C11)perfluoroalkyl carboxylic
acids or metal salts thereof, (C4-C12) perfluoroalkyl sulfonic acids or metal
salts thereof, perfluorooctanesulfonic acid diethanol amide, N-propyl-N-(2-
hydroxyethyl)perfluorooctanesulfone amide, (C6-
C10)perfluoroalkylsulfoneamidepropyltrimethylammonium salts, salts of (C6-
C10)perfluoroalkyl-N-ethylsulfonyl glycin, and (C6-
C16)monoperfluoroalkylethyl phosphates. Examples of the commercially
available surfactants having a fluoroalkyl group include Surflon S-111, S-112
and S-113 (manufactured by Asahi Glass Co.); Frorard FC-93, FC-95, FC-98
and FC-129 (manufactured by Sumitomo 3M Ltd.); Unidyne DS-101 and DS-
102 (manufactured by Daikin Industries, Ltd.); Megafac F-110, F-120, F-113,
F-191, F-812 and F-833 (manufactured by Dainippon Ink and Chemicals, Inc.);
ECTOP EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201 and 204
(manufactured by Tohchem Products Co.); and Futargent F-100 and F150
(manufactured by Neos Co.).
Examples of the cationic surfactants include amine salts, and


quaternary amine salts. Examples of the amine salts include alkyl amine salts,
aminoalcohol fatty acid derivatives, polyamine fatty acid derivatives, and
imidazolines. Examples of the quaternary ammonium salts include
alkyltrimethyl ammonium salts, dialkyldimethyl ammonium salts,
alkyldimethyl benzyl ammonium salts, pyridinium salts, alkyl isoquinolinium
salts, and benzethonium chlorides. Among these, preferable examples are
primary, secondary or tertiary aliphatic amine acids having a fluoroalkyl
group, aliphatic quaternary ammonium salts such as (C6-C10)perfluoroalkyl
sulfoneamidepropyltrimethylammoniurn salts, benzalkonium salts,
benzetonium chlorides, pyridinium salts, and imidazolinium salts. Specific
examples of commercially available products thereof include Surflon S-121
(manufactured by Asahi Glass Co.), Frorard FC-135 (manufactured by
Sumitomo 3M Ltd.), Unidyne DS-202 (manufactured by Daikin Industries,
Ltd.), Megaface F-150 and F-824 (manufactured by Dainippon Ink and
Chemicals, Inc.), Ectop EF-132 (manufactured by Tohchem Products Co.), and
Futargent F-300 (manufactured by Neos Co.).
Examples of the nonionic surfactants include fatty acid amide
derivatives, and polyalcohol derivatives.
Examples of the ampholytic surfactants include alanine,
dodecyldi(aminoethyl)glycin, di(octylaminoethyle)glycin, and N-alkyl-N,N-
dimethylammonium betaine.
Examples of the water-insoluble inorganic dispersing agents include


tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and
hydroxyl apatite.
Examples of the polymeric protective colloids include acids, hydroxyl
group-containing (meth)acryl monomers, vinyl alcohol or ethers thereof, esters
of vinyl alcohol and carboxyl group-containing compounds, amide compounds
or methylol compounds thereof, chlorides, homopolymers or copolymers of
monomers containing a nitrogen atom or heterocyclic ring containing a
nitrogen atom, polyoxyethylenes, and celluloses.
Examples of the acids include acrylic acid, methacrylic acid, α-
cycnoacrylic acid, α-cycnomethacrylic acid, itaconic acid, crotonic acid,
fumaric acid, maleic acid, and maleic anhydride. Examples of the hydroxyl
group-containing (meth)acryl monomers include p-hydroxyethyl acrylate, β-
hydroxyethyl methacrylate, β-hydroxypropyl acrylate, (3-hydroxypropyl
methacrylate, γ-hydroxypropyl acrylate, γ-hydroxypropyl methacrylate, 3-
chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate,
diethyleneglycol monoacrylats, diethyleneglycol monomethacrylate, glycerin
monoacrylate, glycerin monomethacrylate, N-methylol acrylamide, and N-
methylol methacrylamide. Examples of ethers of vinyl alcohol include vinyl
methyl ether, vinyl ethyl ether, and vinyl propyl ether. Examples of esters of
vinyl alcohol and carboxyl group-containing compounds include vinyl acetate,
vinyl propionate, and vinyl butyrate. Examples of the amide compounds or
methylol compounds thereof include acrylamide, methacrylamide, diacetone


acrylicamide acid, and methylol compounds thereof. Examples of the
chlorides include acrylic chloride, and methacrylic chloride. Examples of the
homopolymers or copolymers having a nitrogen atom or heterocyclic ring
containing a nitrogen atom include vinyl pyridine, vinyl pyrrolidone, vinyl
imidazole, and ethylene imine. Examples of the polyoxyethylenes include
polyoxyethylene, polyoxypropylene, polyoxyethylene alkylamines,
polyoxypropylene alkylamines, polyoxyethylene alkylamides,
polyoxypropylene alkylamides, polyoxyethylene nonylphenylethers,
polyoxyethylene laurylphenylethers, polyoxyethylene stearylarylphenyl esters,
and polyoxyethylene nonylphenyl esters. Examples of the celluloses include
methyl cellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.
Upon preparation of the dispersion, a dispersion stabilizer may be
used as needed. Examples of the dispersion stabilizer include calcium
phosphate and the like, which are soluble in acids or alkalis.
When calcium phosphate is employed as a dispersion stabilizer, the
dispersion stabilizer can be removed from particles by dissolving it in an acid
such as hydrochloric acid, and by washing the particles with water or
decomposing the dispersion stabilizer with oxygen.
Upon preparation of the dispersion it is possible to use a catalyst for
the extension or crosslingking reaction. Examples of such a catalyst include
dibutyl tin laurate and dioctyl tin laurate.
An organic solvent is removed from the resultant dispersion


(emulsified slurry). Examples of the method of removing the organic solvent
include (1) a method in which the reaction system is gradually heated to
completely evaporate the organic solvent present in oil droplets, and (2) a
method in which solid dispersions are sprayed in a dry atmosphere to
completely remove a water-insoluble organic solvent in oil droplets to produce
toner particles, along with evaporation of an aqueous dispersing agent.
After removal of the organic solvent, toner particles are formed. The
toner particles may be further washed and dried. Subsequently, the toner
particles may be optionally classified. Classification can be carried out by
removing fine particles in the solution by cyclone, decantation, centrifugation,
etc. Alternatively, classification may be carried out after dry toner particles
are obtained as powder.
The toner particles thus obtained are mixed with such particles as the
colorant, releasing agent, charge controlling agent, etc., and mechanical impact
is applied thereto, thereby preventing particles such as the releasing agent from
falling off the surfaces of the toner particles.
Examples of the method of applying mechanical impact include a
method in which impact is applied to the mixture by means of a blade rotating
at high speed, and a method in which impact is applied by introducing the
mixture into a high-speed flow to cause particles collide with each other or to
cause composite particles to collide against an impact board. Examples of a
device employed for these method include angmill (manufactured by


Hosokawamicron Corp.), modified I-type mill (manufactured by Nippon
Pneumatic Mfg. Co., Ltd.) to decrease crushing air pressure, hybridization
system (manufactured by Nara Machinery Co., Ltd.), krypton system
(manufactured by Kawasaki Heavy Industries, Ltd.), and automatic mortars.
The color of the toner is not particularly limited and can be
appropriately determined depending on the intended purpose; it is at least one
of a black toner, cyan toner, magenta toner and yellow toner. Toners of
different colors can be obtained by using different colorant accordingly; a
color toner is preferable.

The developer used in the present invention comprises the toner of the
present invention and appropriately selected additional ingredient(s) such as a
carrier. The developer may be either a one-component or a two-component
developer; however, when it is applied to high-speed printers that support
increasing information processing rates of recent years, a two-component
developer is preferable for the purpose of achieving an excellent shelf life.
In the case of a one-component developer comprising the toner of the
present invention, variations in the toner particle diameter are minimized even
after consumption or addition of toner, and toner filming to a developing roller
and toner adhesion to members (e.g., blade) due to its reduced layer thickness
are prevented. Thus, it is possible to provide excellent and stable developing
properties and images even after a long time usage of the developing unit (i.e.,


after long time agitation of developer). Meanwhile, in the case of a two-
component developer comprising the toner of the present invention, even after
many cycles of consumption and addition of toner, the variations in the toner
particle diameter are minimized and, even after a long time agitation of the
developer in the developing unit, excellent and stable developing properties
may be obtained.
The carrier is not particularly limited and can be appropriately
selected depending on the intended purpose. However, the carrier is preferably
selected from those having a core material and a resin layer coating the core
material.
Materials for the core are not particularly limited and can be
appropriately selected from conventional materials; for example, materials
based on manganese-strontium (Mn-Sr) of 50 emu/g to 90 emu/g and materials
based on manganese-magnesium (Mn-Mg) are preferable. From the standpoint
of securing image density, high magnetizing materials such as iron powder
(100 emu/g or more) and magnetite (75 emu/g to 120 emu/g) are preferable. In
addition, weak magnetizing materials such as copper-zinc (Cu-Zn)-based
materials (30 emu/g to 80 emu/g) are preferable from the standpoint for
achieving higher-grade images by reducing the contact pressure against the
photoconductor having standing toner particles. These materials may be used
singly or in combination.
The particle diameter of the core material, in terms of volume-average


particle diameter (D50), is preferably 10 µm to 120 µm and, more preferably,
40 µm to 100 µm.
If the average particle diameter (volume-average particle diameter
(D50)) is less than 10 µm, fine particles make up a large proportion of the
carrier particle distribution, causing in some cases carrier splash due to
reduced magnetization per one particle; on the other hand, if it exceeds 150
µm, the specific surface area of the particles decreases, causing toner splashes
and reducing the reproducibility of images, particularly the reproducibility of
solid-fills in full-color images.
Materials for the resin layer are not particularly limited and can be
appropriately selected from conventional resins depending on the intended
purpose; examples include amino resins, polyvinyl resins, polystyrene resins,
halogenated olefin resins, polyester resins, polycarbonate resins, polyethylene
resins, polyvinyl fluoride resins, polyvinylidene fluoride resins,
polytrifluoroethylene resins, polyhexafluoropropylene resins, copolymers of
vinylidene fluoride and acrylic monomers, copolymers of vinylidene fluoride
and vinyl fluoride, fluoroterpolymers such as terpolymers of
tetrafluoroethylene, vinylidene fluoride and non-fluoride monomers, and
silicone resins. These resins may be used singly or in combination.
Examples of the amino resins include urea-formaldehyde resins,
melamine resins, benzoguanamine resins, urea resins, polyamide resins, and
epoxy resins. Examples of the polyvinyl resins include acrylic resins,


polymethyl methacrylate resins, polyacrylonitrile resins, polyvinyl acetate
resins, polyvinyl alcohol resins, and polyvinyl butyral resins. Examples of the
polystyrene resins include polystyrene resins, and styrene-acryl copolymer
resins. Examples of the halogenated olefin resins include polyvinyl chloride.
Examples of the polyester resins include polyethylene terephthalate resins, and
polybutylene terephthalate resins.
The resin layer may contain such material as conductive powder
depending on the application; for the conductive powder, metal powder, carbon
black, titanium oxide, tin oxide, zinc oxide, and the like are exemplified.
These conductive powders preferably have an average particle diameter of 1
µm or less. If the average particle diameter is greater than 1 µm, it may be
difficult to control electrical resistance.
The resin layer may be formed by dissolving the silicone resin or the
like into a solvent to prepare a coating solution, uniformly coating the surface
of the core material with the coating solution by a known coating process, and
dying and baking the core material. Examples of the coating process include
immersing process, spray process, and brush painting process,
The solvent is not particularly limited and can be appropriately
determined depending on the intended purpose. Examples include toluene,
xylene, methyl ethyl ketone, methyl isobutyl ketone, cellusolve, and
butylacetate.
The baking process may be an externally heating process or an


internally heating process, and can be selected from, for example, a process
using a fixed type electric furnace, a fluid type electric furnace, a rotary type
electric furnace or a burner furnace, and a process using microwave.
The content of the resin layer in the carrier is preferably 0.01% by
mass to 5.0% by mass. Tf the content is less than 0.01% by mass, it may be
difficult to form a uniform resin layer on the surface of the core material, on
the other hand, if the content exceeds 5.0% by mass, the resin layer becomes so
thick that carrier particles may coagulate together. Thus, it may result in
failure to obtain uniform carrier particles.
When the developer is a two-component developer, the content of the
carrier in the two-component developer is not particularly limited and may be
appropriately determined depending on the intended purpose; for example, it is
preferably 90% by mass to 98 % by mass, more preferably 93% by mass to 97
% by mass.
In the case of a two-component developer, toner is generally mixed
with carrier in an amount of 1 part by mass to 10 parts by mass per 100 parts
by mass of carrier.
Since the developer of the present invention comprises the toner of the
present invention, it allows toner particles to be densely packed in a toner
image, can provide high-definition images with reduced image layer thickness,
and can achieve long-term stable removability.
The developer can be suitably applied to a variety of known


electrophotographic image formation processes including a magnetic one-
component developing process, non-magnetic one-component developing
process, and two-component developing process, particularly to a toner
container, process cartridge, image forming apparatus and image forming
method of the present invention, all of which will be described below.
(Toner Container)
The toner container of the present invention is a container supplied
with the toner or developer of the present invention.
The toner container is not particularly limited and can be
appropriately selected from conventional containers; for example, a toner
container having a container main body and a cap is a suitable example.
The size, shape, structure, material and other several features of the
container main body is not particularly limited and can be appropriately
determined depending on the intended purpose. For example, the container
main body preferably has a cylindrical shape, most preferably a cylindrical
shape in which spiral grooves are formed on its inner surface that allow toner
in the container to shift to the outlet along with rotation of the main body, and
in which all or part of the spiral grooves have a bellow function.
Materials for the container main body are not particularly limited and
are preferably those capable of providing accurate dimensions when fabricated;
examples include resins. For example, polyester resins, polyethylene resins,
polypropylene resins, polystyrene resins, polyvinyl chloride resins, polyacrylic


acid resins, polycarbonate resins, ABS resins, and polyacetal resins are suitable
examples.
The toner container of the present invention can be readily stored and
transferred, and is easy to handle. The toner container can be suitably used for
the supply of toner by detachably attaching it to a process cartridge, image
forming apparatus, etc., of the present invention to be described later.
(Process Cartridge)
The process cartridge of the present invention comprises a latent
electrostatic image bearing member configured to bear a latent electrostatic
image, and a developing unit configured to develop the latent electrostatic
image formed on the latent electrostatic image bearing member using a
developer to thereby form a visible image, and further comprises additional
unit(s) appropriately selected.
The developing unit comprises a developer container for storing the
toner or developer of the present invention, and a developer carrier for carrying
and transferring the toner or developer stored in the developer container, and
may further comprises a layer-thickness control member for controlling the
thickness of the layer of toner to be carried.
The process cartridge of the present invention can be detachably
attached to various electrophotographic apparatus, faxes, and printers,
particularly to the image forming apparatus of the present invention to be
described later.


The process cartridge of the present invention comprises, for example,
as shown in Fig. 4, a built-in photoconductor 101, a charging unit 102, a
developing unit 104 and a cleaning unit 107 and, if necessary, further
comprises additional unit(s).
For the photoconductor 101, a photoconductor similar to that
described above can be used.
For an exposure unit 103, a light source capable of high-definition
exposure is used.
For the charging unit 102, an arbitrary charging member can be used.
The image forming apparatus of the present invention comprises the
latent electrostatic image bearing member, developing device, cleaning device,
etc., which are integrated into a process cartridge. This unit may be detachably
attached to the apparatus itself. Alternatively, at least one of a charging
device, exposing device, developing device and transferring or separating
device are supported together with the latent electrostatic image bearing
member to form a process cartridge, thus forming a single unit that can be
detachably attached to the apparatus by means of guide means (e.g., rails)
provided in the apparatus.
(Image Formation Method and Image Formation Apparatus)
The image forming apparatus of the present invention comprises an
latent electrostatic image bearing member, a latent electrostatic image forming
unit, a developing unit, a transferring unit and a fixing unit, and further


comprises additional unit(s) such as a charge eliminating unit, a cleaning unit,
a recycling unit and a controlling unit, which are optionally selected as needed.
The image forming method of the present invention comprises a latent
electrostatic image forming step, a developing step, a transferring step and a
fixing step, and further comprises additional step(s) such as a charge removing
step, a cleaning step, a recycling step and/or a controlling step, which are
optionally selected as needed.
The image forming method of the present invention can be suitably
performed using the image forming apparatus of the present invention. The
latent electrostatic image forming step is performed by the latent electrostatic
image forming unit, the developing step is performed by the developing unit,
the transferring step is performed by the transferring unit, the fixing step is
performed by the fixing unit, and the additional steps can be performed by the
additional units.
-Latent Electrostatic Image Forming Step and Latent Electrostatic Image
Forming Unit -
The latent electrostatic image forming step is a step of forming a
latent electrostatic image on a latent electrostatic image bearing member.
The material, shape, size, structure, and several features of the latent
electrostatic image bearing member (referred to as "photoconductor" or
"electrophotographic photoconductor" in some cases) are not particularly
limited. The latent electrostatic image bearing member can be appropriately


selected from those known in the art. However, a drum shaped-latent
electrostatic image bearing member is a suitable example. For the material
constituting the latent electrostatic image bearing member, inorganic
photoconductive materials such as amorphous silicon and selenium, and
organic photoconductive materials such as polysilane and phthalopolymethine
are preferable. Among these, amorphous silicon is preferable in view of its
long life.
The formation of the latent electrostatic image is achieved by, for
example, exposing the latent electrostatic image bearing member imagewisely
after equally charging its entire surface. This step is performed by means of
the latent electrostatic image forming unit.
The latent electrostatic image forming unit comprises a charging
device configured to equally charge the surface of the latent electrostatic image
bearing member, and an exposing device configured to imagewisely expose the
surface of the latent electrostatic image bearing member.
The charging step is achieved by, for example, applying voltage to the
surface of the latent electrostatic image bearing member by means of the
charging unit.
The charging device is not particularly limited and can be
appropriately selected depending on the intended purpose; examples include
known contact-charging devices equipped with a conductive or semiconductive
roller, blush, film or rubber blade; and known non-contact-charging devices


utilizing corona discharge such as corotron or scorotoron.
The exposure step is achieved by, for example, selectively exposing
the surface of the photoconductor by means of the exposing device.
The exposing device is not particularly limited as long as it is capable
of performing image-wise exposure on the surface of the charged latent
electrostatic image bearing member by means of the charging device, and may
be appropriately selected depending on the intended use; examples include
various exposing devices, such as optical copy devices, rod-lens-eye devices,
optical laser devices, and optical liquid crystal shatter devices.
Note in the present invention that a backlight system may be
employed for exposure, where image-wise exposure is performed from the
back side of the latent electrostatic image bearing member.
-Developing and Developing Unit -
The developing step is a step of developing the latent electrostatic
image using the toner or developer of the present invention to form a visible
image.
The formation of the visible image can be achieved, for example, by
developing the latent electrostatic image using the toner or developer of the
present invention. This is performed by means of the developing unit.
The developing unit is not particularly limited as long as it is capable
of development by means of the toner or developer of the present invention,
and can be appropriately selected from known developing units depending on


the intended purpose; suitable examples include those having at least a
developing device, which is capable of housing the toner or developer of the
present invention therein and is capable of directly or indirectly applying the
toner or developer to the latent electrostatic image. A developing device
equipped with the toner container of the present invention is more preferable.
The developing device may be of dry developing type or wet
developing type, and may be designed either for monochrome or multiple-
color; suitable examples include those having an agitation unit for agitating the
toner or developer to provide electrical charges by frictional electrification,
and a rotatable magnet roller.
In the developing device the toner and carrier are mixed together and
the toner is charged by friction, allowing the rotating magnetic roller to bear
toner particles in such a way that they stand on its surface. In this way a
magnetic blush is formed. Since the magnet roller is arranged in the vicinity of
the latent electrostatic image bearing member (photoconductor), some toner
particles on the magnetic roller that constitute the magnetic blush electrically
migrate to the surface of the latent electrostatic image bearing member
(photoconductor). As a result, a latent electrostatic image is developed by
means of the toner, forming a visible image, or a toner image, on the surface of
the latent electrostatic image bearing member (photoconductor).
-Transferring and Transferring Unit-
The transferring step is a step of transferring the visible image to a


recording medium. A preferred embodiment of transferring involves two
steps: primary transferring in which the visible image is transferred to an
intermediate transferring medium; and secondary transferring in which the
visible image transferred to the intermediate transferring medium is transferred
to a recording medium. A more preferable embodiment of transferring
involves two steps: primary transferring in which a visible image is transferred
to an intermediate transferring medium to form a complex image thereon by
means of toners of two or more different colors, preferably full-color toners;
and secondary transferring in which the complex image is transferred to a
recording medium.
The transferring step is achieved by, for example, charging the latent
electrostatic image bearing member (photoconductor) by means of a transfer
charging unit. This transferring step is performed by means of the transferring
unit. A preferable embodiment of the transferring unit has two units: a
transferring unit configured to transfer a visible image to an intermediate
transferring medium to form a complex image; and a secondary transferring
unit configured to transfer the complex image to a recording medium.
The intermediate transferring medium is not particularly limited and
can be selected from conventional transferring media depending on the
intended purpose; suitable examples include transferring belts.
The transferring unit (i.e., the primary and secondary transferring
units) preferably comprises a transferring device configured to charge and


separate the visible image from the latent electrostatic image bearing member
(photoconductor) and transfer it to the recording medium. The number of the
transferring device to be provided may be either 1 or more.
Examples of the transferring device include corona transferring
devices utilizing corona discharge, transferring belts, transferring rollers,
pressure-transferring rollers, and adhesion-transferring devices.
The recording medium is generally standard paper and can be
appropriately determined depending on the intended purpose as long as it is
capable of receiving developed, unfixed image thereon. PET bases for OHP
can also be used.
The fixing step is a step of fixing a transferred visible image to a
recording medium by means of the Fixing unit. Fixing may be performed every
time after each different toner has been transferred to the recording medium or
may be performed in a single step after all different toners have been
transferred to the recording medium.
The fixing unit is not particularly limited and can be appropriately
selected depending on the intended purpose; examples include a heating-
pressurizing unit. The heating-pressurizing unit is preferably a combination of
a heating roller and a pressurizing roller, or a combination of a heating roller, a
pressurizing roller, and an endless belt, for example.
In general, heating treatment by means of the heating-pressurizing
unit is preferably performed at a temperature of 80°C to 200°C.


Note in the present invention that a known optical fixing unit may be
used in combination with or instead of the fixing step and fixing unit,
depending on the intended purpose.
The charge removing step is a step of applying a bias to the charged
electrogphotoraphic photoconductor for removal of charges. This is suitably
performed by means of the charge eliminating unit.
The charge removing unit is not particularly limited as long as it is
capable of applying a charge removing bias to the latent electrostatic image
bearing member, and can be appropriately selected from conventional charge
eliminating units depending on the intended purpose. A suitable example
thereof is a charge removing lamp and the like.
The cleaning step is a step of removing toner particles remained on
the latent electrostatic image bearing member. This is suitably performed by
means of the cleaning unit.
The cleaning unit is not particularly limited as long as it is capable of
removing such toner particles from the latent electrostatic image bearing
member, and can be suitably selected from conventional cleaners depending on
the intended use; examples include a magnetic blush cleaner, a electrostatic
brush cleaner, a magnetic roller cleaner, a blade cleaner, a blush cleaner, and a
wave cleaner
The recycling step is a step of recovering the toner particles removed
through the cleaning step to the developing unit. This is suitably performed by


means of the recycling unit.
The recycling unit is not particularly limited, and can be appropriately
selected from conventional conveyance systems.
The controlling step is a step of controlling the foregoing steps. This
is suitably performed by means of the controlling unit.
The controlling unit is not particularly limited as long as the operation
of each step can be controlled, and can be appropriately selected depending on
the intended use. Examples thereof include equipment such as sequencers and
computers.
One embodiment of the image forming method of the present
invention by means of the image forming apparatus of the present invention
will be described with reference to FIG. 5. An image forming apparatus 100
shown in FIG. 5 comprises a photoconductor drum 10 (hereinafter referred to
as a photoconductor 10) as the latent electrostatic image bearing member, a
charging roller 20 as the charging unit, an exposure device 30 as the exposing
unit, a developing device 40 as the developing unit, an intermediate
transferring member 50, a cleaning device 60 having a cleaning blade as the
cleaning unit, and a charge removing lamp 70 as the charge removing unit.
The intermediate transferring member 50 is an endless belt, and is so
designed that it loops around three rollers 51 disposed its inside and rotates in
the direction shown by the arrow by means of the rollers 51. One or more of
the three rollers 51 also functions as a transfer bias roller capable of applying a


certain transfer bias (primary bias) to the intermediate transferring member 50.
The cleaning device 90 having a cleaning blade is provided adjacent to the
intermediate transferring member 50. There is provided a transferring roller 80
next to the intermediate transferring member 50 as the transferring unit capable
of applying a transfer bias to transfer a developed image (toner image) to a
transfer sheet 95, a recording medium (secondary transferring). Moreover,
there is provided a corona charger 58 around the intermediate transferring
member 50 for applying charges to the toner image transferred on the
intermediate transferring medium 50. The corona charger 58 is arranged
between the contact region of the photoconductor 10 and the intermediate
transferring medium 50 and the contact region of the intermediate transferring
medium 50 and the transfer sheet 95.
The developing device 40 comprises a developing belt 41 (a developer
bearing member), a black developing unit 45K, yellow developing unit 45Y,
magenta developing unit 45M and cyan developing unit 45C, the developing
units being positioned around the developing belt 41. The black developing
unit 45K comprises a developer container 42K, a developer supplying roller
43K, and a developing roller 44K. The yellow developing unit 45Y comprises
a developer container 42Y, a developer supplying roller 43Y, and a developing
roller 44Y. The magenta developing unit 45M comprises a developer
container 42M, a developer supplying roller 43M, and a developing roller
44M. The cyan developing unit 45C comprises a developer container 42C, a


developer supplying roller 43C, and a developing roller 44C. The developing
belt 41 is an endless belt looped around a plurality of belt rollers so as to be
rotatable. A part of the developing belt 41 is in contact with the latent
electrostatic image bearing member 10.
In the image forming apparatus 100 shown in FIG. 5, the
photoconductor drum 10 is uniformly charged by means of, for example, the
charging roller 20. The exposure device 30 then applies a light beam to the
photoconductor drum 10 so as to form a latent electrostatic image. The latent
electrostatic image formed on the photoconductor drum 10 is provided with
toner from the developing device 40 to form a visible image (toner image).
The roller 51 applies a bias to the toner image to transfer the visible image
(toner image) to the intermediate transferring medium 50 (primary
transferring), and the toner image is then transferred to the transfer sheet 95
(secondary transferring). In this way a transferred image is formed on the
transfer sheet 95. Thereafter, toner particles remained on the photoconductor
drum 10 are removed by means of the cleaning device 60, and charges of the
photoconductor drum 10 are removed by means of the charge removing lamp
70 on a temporary basis.
Another embodiment of the image forming method of the present
invention by means of the image forming apparatus of the present invention
will be described with reference to FIG. 6. The image forming apparatus 100
shown in FIG. 6 has an identical configuration and working effects to those of


the image forming apparatus 100 shown in FIG. 5 except that this image
forming apparatus 100 does not comprise the developing belt 41 and that the
black developing unit 45K, yellow developing unit 45Y, magenta developing
unit 45M and cyan developing unit 45C are disposed around the periphery of
the photoconductor 10. Note in FIG. 6 that members identical to those in FIG.
5 are denoted by the same reference numerals.
Still another embodiment of the image forming method of the present
invention by means of the image forming apparatus of the present invention
will be described with reference to FIG. 7. An image forming apparatus 100
shown in FIG. 7 is a tandem color image-forming apparatus. The tandem
image forming apparatus comprises a copy machine main body 150, a feeder
table 200, a scanner 300, and an automatic document feeder (ADF) 400.
The copy machine main body 150 has an endless-belt intermediate
transferring member 50 in the center. The intermediate transferring member
50 is looped around support rollers 14, 15 and 16 and is configured to rotate in
a clockwise direction in FIG. 7. A cleaning device 17 for the intermediate
transferring member is provided in the vicinity of the support roller 15. The
cleaning device 17 removes toner particles remained on the intermediate
transferring member 50. On the intermediate transferring member 50 looped
around the support rollers 14 and 15, four color-image forming devices 18 -
yellow, cyan, magenta, and black - are arranged, constituting a tandem
developing unit 120. An exposing unit 21 is arranged adjacent to the tandem


developing unit 120. A secondary transferring unit 22 is arranged across the
intermediate transferring member 50 from the tandem developing unit 120.
The secondary transferring unit 22 comprises a secondary transferring belt 24,
an endless belt, which is looped around a pair of rollers 23. A paper sheet on
the secondary transferring belt 24 is allowed to contact the intermediate
transferring member 50. An image fixing device 25 is arranged in the vicinity
of the secondary transferring unit 22. The image fixing device 25 comprises a
fixing belt 26, an endless belt, and a pressurizing roller 27 which is pressed by
the fixing belt 26.
In the tandem image forming apparatus, a sheet reverser 28 is
arranged adjacent to both the secondary transferring unit 22 and the image-
fixing device 25. The sheet reverser 28 turns over s a transferred sheet to form
images on the both sides of the sheet.
Next, full-color image formation (color copying) using the tandem
developing unit will be described. At first, a source document is placed on a
document tray 130 of the automatic document feeder 400. Alternatively, the
automatic document feeder 400 is opened, the source document is placed on a
contact glass 32 of a scanner 300, and the automatic document feeder 400 is
closed.
When a start switch (not shown) is pushed, the source document
placed on the automatic document feeder 400 is transferred to the contact glass
32, and the scanner is then driven to operate first and second carriages 33 and


34. In a case where the source document is originally placed on the contact
glass 32, the scanner 300 is immediately driven after pushing of the start
switch. A light beam is applied from a light source to the document by means
of the first carriage 33, and the light beam reflected from the document is
further reflected by the mirror of the second carriage 34. The reflected light
beam passes through an image-forming lens 35, and a read sensor 36 receives
it. In this way the color document (color image) is scanned, producing 4 types
of color information - black, yellow, magenta, and cyan.
Each piece of color information (black, yellow, magenta, and cyan) is
transmitted to the image forming unit 18 (black image forming unit, yellow
image forming unit, magenta image forming unit, or cyan image forming unit)
of the tandem developing unit 120, and toner images of each color are formed
in the image-forming units 18. As shown in FIG. 8, each of the image-forming
units 18 (black image-forming unit, yellow image forming unit, magenta image
forming unit, and cyan image forming unit) of the tandem developing unit 120
comprises: a latent electrostatic image bearing member 10 (latent electrostatic
image bearing member for black 10K, latent electrostatic image bearing
member for yellow 10Y, latent electrostatic image bearing member for
magenta 10M, or latent electrostatic image bearing member for cyan 10C); a
charging device 60 for uniformly charging the latent electrostatic image
bearing member; an exposing unit for forming a latent electrostatic image
corresponding to the color image on the latent electrostatic image bearing


member by exposing it to light (denoted by "L" in FIG. 8) on the basis of the
corresponding color image information; a developing device 61 for developing
the latent electrostatic image using the corresponding color toner (black toner,
yellow toner, magenta toner, or cyan toner) to form a toner image; a transfer
charger 62 for transferring the toner image to the intermediate transferring
member 50; a cleaning device 63; and a charge removing device 64. Thus,
images of different colors (a black image, a yellow image, a magenta image,
and a cyan image) can be formed based on the color image information. The
black toner image formed on the photoconductor for black 10K, yellow toner
image formed on the photoconductor for yellow 10Y, magenta toner image
formed on the photoconductor for magenta 10M, and cyan toner image formed
on the photoconductor for cyan 10C are sequentially transferred to the
intermediate transferring member 50 which rotates by means of support rollers
14, 15 and 16 (primary transferring). These toner images are overlaid on the
intermediate transferring member 50 to form a composite color image (color
transferred image).
Meanwhile, one of feed rollers 142 of the feed table 200 is selected
and rotated, whereby sheets (recording sheets) are ejected from one of multiple
feed cassettes 144 in the paper bank 143 and are separated one by one by a
separation roller 145. Thereafter, the sheets are fed to a feed path 146,
transferred by a transfer roller 147 into a feed path 148 inside the copying
machine main body 150, and are bumped against a resist roller 49 to stop.


Alternatively, one of the feed rollers 142 is rotated to eject sheets (recording
sheets) placed on a manual feed tray. The sheets are then separated one by one
by means of a separation roller 52, fed into a manual feed path 53, and
similarly, bumped against the resist roller 49 to stop. Note that the resist roller
49 is generally earthed, but may be biased for removing paper dusts on the
sheets.
The resist roller 49 is rotated synchronously with the movement of the
composite color image on the intermediate transferring member 50 to transfer
the sheet (recording sheet) into between the intermediate transferring member
50 and the secondary transferring unit 22, and the composite color image is
transferred to the sheet by means of the secondary transferring unit 22
(secondary transferring). In this way the color image is formed on the sheet.
Note that after image transferring, toner particles remained on the intermediate
transferring member 50 are removed by means of the cleaning device 17.
The sheet (recording sheet) bearing the transferred color image is
conveyed by the secondary transferring unit 22 into the image fixing device 25,
where the composite color image (color transferred image) is Fixed to the sheet
(recording sheet) by heat and pressure. Thereafter, the sheet changes its
direction by action of a switch hook 55, ejected by an ejecting roller 56, and
stacked on an output tray 57. Alternatively, the sheet changes its direction by
action of the switch hook 55, flipped over by means of the sheet reverser 28,
and transferred back to the image transfer section for recording of another


image on the other side. The sheet that bears images on both sides is then
ejected by means of the ejecting roller 56, and is stacked on the output tray 57.
Since the image forming method and image forming apparatus of the
present invention uses the toner of the present invention, which the toner
allows toner particles to be densely packed in a toner image, can provide high-
definition images with reduced image layer thickness and can achieve long-
term stable removability, it is possible to form sharp, high-quality images.
Hereinafter Examples of the present invention will be described,
which however shall not be construed as limiting the invention thereto. It
should be noted that "part(s)" means "part(s) by mass" unless otherwise noted.
(Example 1)
- Synthesis of Emulsion of Organic Particles -
A reaction vessel equipped with a stirrer and a thermometer was
charged with 683 parts of water, 11 parts of a sodium salt of sulfuric acid ester
of ethylene oxide adduct of methacrylic acid (Eleminol RS-30, produced by
Sanyo Chemical Industries Co.), 83 parts of styrene, 83 parts of methacrylic
acid, 110 parts of butyl acrylate, and 1 part of ammonium persulfate, followed
by agitatation for 15 minutes at 400 rpm to produce a white liquid emulsion.
The inside of the reaction vessel was heated to 75 °C for 5 hours for reaction.
To the reaction vessel was added 30 parts of a 1% aqueous solution of
ammonium persulfate, and the reaction vessel was allowed to stand for 5 hours
at 75°C to produce an aqueous dispersion of vinyl resin (a copolymer


consisting of styrene, methacrylic acid, butyl acrylate, and sodium salt of
sulfuric acid ester of ethylene oxide adduct of methacrylic acid) - Particle
Dispersion 1.
The volume-average particle diameter of Particle Dispersion 1
measured using a laser diffraction particle size analyzer (LA-920, SHIMADZU
Corp.) was 105 nm. In addition, an aliquot of Particle Dispersion 1 was dried
to isolate a resin component. The glass transition temperature (Tg) of the resin
component was determined to be 59°C, and its weight-average molecular
weight (Mw) was determined to be 150,000.
- Preparation of Aqueous Phase -
For preparation of an aqueous phase, 990 parts of water, 99 parts of
Particle Dispersion 1, 35 parts of a 48.5% aqueous solution of sodium
dodecyldiphenylether disulfonate (Eleminol MON-7, produced by Sanyo
Chemical Industries Co.), and 60 parts of ethyl acetate were mixed to produce
a creamy white liquid. This was used as Aqueous Phase 1.
- Synthesis of Low Molecular Polyester -
A reaction vessel equipped with a condenser tube, a stirrer and a
nitrogen gas inlet tube was charged with 229 parts of 2 mole ethylene oxide
adduct of bisphenol A, 529 parts of 3 mole propylene oxide adduct of
bisphenol A, 208 parts of terephthalic acid, 46 parts of adipic acid, and 2 parts
of dibutyl tin oxide, allowing reaction to take place for 8 hours at 230°C under
normal pressure. The reaction was continued for a further 5 hours under


reduced pressure (10-15 mmHg). Thereafter, 44 parts of anhydride trimellitic
acid was added to the reaction vessel to allow reaction to take place for 1.8
hour at 180°C under normal pressure. In this way Low Molecular Polyester 1
was synthesized.
Low Molecular Polyester 1 thus obtained had a number-average
molecular weight (Mn) of 2,500, weight-average molecular weight (Mw) of
6,700, peak molecular weight of 5,000, glass transition temperature (Tg) of
43°C, and acid value of 25.
- Synthesis of Intermediate Polyester -
A reaction vessel equipped with a condenser tube, a stirrer and a
nitrogen gas inlet tube was charged with 682 parts of 2 mole ethylene oxide
adduct of bisphenol A, 81 parts of 2 mole propylene oxide adduct of bisphenol
A, 283 parts of terephthalic acid, 22 parts of anhydride trimellitic acid, and 2
parts of dibutyl tin oxide, allowing reaction to take place for 8 hours at 230°C
under normal pressure. The reaction was continued for a further 5 hours under
reduced pressure (10-15 mmHg) to produce Intermediate Polyester 1.
Intermediate Polyester 1 thus obtained had a number-average
molecular weight (Mn) of 2,100, weight-average molecular weight (Mw) of
95,00, glass transition temperature (Tg) of 55°C, acid value of 5, and hydroxyl
value of 51.
Subsequently, a reaction vessel equipped with a condenser tube, a
stirrer and a nitrogen inlet tube was charged with 410 parts of Intermediate


Polyester 1, 89 parts of isophorone diisocyanate, and 500 parts of ethyl acetate,
allowing reaction to take place for 5 hours at 100°C to produce Prepolymer 1.
The content of free isocyanates in Prepolymer 1 was 1.53% by mass.
- Synthesis of Ketimine Compound -
A reaction vessel equipped with a stirrer and a thermometer was
charged with 170 parts of isophorone diamine and 75 parts of methyl ethyl
ketone, allowing reaction to take place for 5 hours at 50°C to produce
Ketimine Compound 1.
The amine value of Ketimine Compound 1 thus obtained was 418.
- Preparation of Master Batch -
Using HENSCHEL MIXER (Mitsui Mining Company, Ltd.), 1200
parts of water, 540 parts of carbon black (Printex 35, produced by Degussa
Corp. DBP absorption = 42 ml/100mg, pH = 9.5), and 1200 parts of polyester
resin were mixed, and further kneaded for 30 minutes at 150°C using a double
roll. Thereafter, the resultant paste was extended by applying pressure, cooled,
and pulverized in a pulverizer to produce Master Batch 1.
- Preparation of Oil Phase -
A reaction vessel equipped with a stirrer and a thermometer was
charged with 378 parts of Low Molecular Polyester 1, 110 parts of carnauba
wax, 32 parts of a charge controlling agent (E-84, zinc salicylate, produced by
Orient Chemical Industries, Ltd.), and 947 parts of ethyl acetate, heated to
80°C with agitation, retained for 5 hours at 80°C, and cooled to 30°C in 1


hour. Subsequently, 500 parts of Master Batch 1 and 500 parts of ethyl acetate
were added to the reaction vessel, and stirred for 1 hour to produce Toner
Constituent Solution 1.
Next, 1324 parts of Toner Constituent Solution 1 thus obtained was
transferred to a reaction vessel, and dispersed using a bead mill
(ULTRAVISCOMILL, manufactured by AIMEX Co., Ltd.) under the
following conditions: Liquid feeding speed = 1 kg/hr, Disc rotation speed = 6
m/sec, Diameter of beads = 0.5 mm, Filling factor = 80% by volume, and the
number of dispersing operations = 3.
In this way the carbon black and wax were dispersed. Subsequently,
1324 parts of a 65% ethyl acetate solution of Low Molecular Polyester 1 was
added to the reaction vessel, followed by another dispersion operation using
the bead mill under the foregoing conditions. Thus, Pigment/Wax Dispersion
1 was obtained.
The proportion of solids in Pigment/Wax Dispersion 1 was 50% by
mass, when measured after heated to 130°C for 30 minutes.
- Emulsification and Solvent Removal Step-
To a reaction vessel was added 749 parts of Pigment/Wax Dispersion
1, 115 parts of Prepolymer 1, and 2.9 parts of Ketimine Compound 1.
Furthermore, 2.0 parts of the solids of an organosilica sol (MEK-ST-UP,
produced by Nissan Chemical Industries, Ltd.) was added to the reaction vessel
and, using a TK homomixer, mixed for 1 minute at 5,000 rpm. Thereafter,


1250 parts of Aqueous Phase 1 was added and mixed using the TK homomixer
for 30 minutes at 12,500 rpm, producing Emulsion Slurry 1.
A reaction vessel equipped with a stirrer and a thermometer was
charged with Emulsion Slurry 1, and heated to 40°C for 5 hours for the
removal of a solvent. The slurry was then allowed to stand for 4 hours at 45°C
to produce Dispersion Slurry 1.
- Washing and drying-
One hundred parts of Dispersion Slurry 1 was filtrated under reduced
pressure, and the filter cake was added to 100 parts of deionized water and
mixed using the TK homomixer for 10 minutes at 12,000 rpm followed by
filtration.
Next, the resultant filter cake was added to 100 parts of a 10% (by
mass) aqueous solution of sodium hydroxide and mixed using the TK
homomixer for 30 minutes at 12,000 rpm followed by filtration under reduced
pressure.
The resultant filter cake was added to 100 parts of a 10% (by mass)
aqueous solution of hydrochloric acid and mixed using the TK homomixer for
10 minutes at 12,000 rpm followed by filtration.
The resultant filter cake was added to 300 parts of deionized water
and mixed using the TK homomixer for 10 minutes at 12,000 rpm followed by
filtration (this procedure was performed twice). In this way Filter Cake 1 was
obtained.


Filter Cake 1 was dried for 48 hours at 45°C in a circulating drier and
sieved through 75 µm mesh to produce Toner 1.
- Addition of External Additive-
To 100 parts of Toner 1 was added 1.5 parts of hydrophobic silica and
mixed using HENSCHEL MIXER to produce toner of Example 1.
(Example 2)
Toner of Example 2 was prepared in a manner similar to that
described in Example 1 except that 2.5 parts of the solids of an organosilica sol
was used in the emulsification and solvent removal step.
(Example 3)
Toner of Example 3 was prepared in a manner similar to that
described in Example 1 except that 3.5 parts of the solids of an organosilica sol
was used in the emulsification and solvent removal step.
(Example 4)
Toner of Example 4 was prepared in a manner similar to that
described in Example 1 except that 4.5 parts of the solids of an organosilica sol
was used in the emulsification and solvent removal step.
(Comparative Example 1)
Toner of Comparative Example 1 was prepared in a manner similar to
that described in Example 1 except that no organosilica sol was added to the
toner in the emulsification and solvent removal step.
(Comparative Example 2)


Through wet pulverization, toner of Comparative Example 2 was
prepared in the following manner using polyester resin synthesized from
bisphenol diol and a polycarboxylic acid.
At first, 86 parts of polyester resin (number-average molecular weight
(Mn) = 6,000, weight-average molecular weight (Mw) = 50,000, and glass
transition temperature (Tg) = 61°C), 10 parts of rice wax (acid value = 0.5),
and 4 parts of copper phthalocyanine blue pigment (produced by TOYO INK
Corp.) were fully mixed using HENSCHEL MIXER, heated and melted using a
roll mill for 40 hours at 80°C to 110°C, and cooled to room temperature. The
resultant paste was pulverized and classified to produce toner particles.
Using HENSCHEL MIXER 1.5 parts of hydrophobic silica was mixed
with 100 parts of the toner particles to prepare toner of Comparative Example
2.
For the toners prepared in Examples 1 to 4 and Comparative
Examples 1 and 2, the surface factors SF-1 and SF-2, small diameter SF-2,
large diameter SF-2, porosity, toner particle diameter (Dv, Dv/Dn), proportion
of toner particles with a circle equivalent diameter of 2 µm or less, and
presence of an inorganic oxide particle layer were determined. The results are
shown in Table 1.

Pictures of toner particles were taken by a scanning electron
microscope (S-800, manufactured by Hitachi Ltd.) and analyzed by an image


analyzer (LUSEX3, manufactured by NIRECO Corp.), calculating the surface
factors SF-1 and SF-2 using the following Equations (1) and (2).
SF-1 = [(MXLNG)2/AREA] x (100π/4) ... Equation (1)
where MXLNG represents the maximum length across a two-
dimensional projection of a toner particle, and AREA represents the area of the
projection
SF-2 = [(PERI)2/AREA] x (100/4Π) ... Equation (2)
where PERI represents the perimeter of a two-dimensional projection
of a toner particle, and AREA represents the area of the projection
less>
The proportion (number%) of toner particles with a given circle
equivalent diameter can be determined using a flow particle image analyzer
(FPIA-2100, manufactured by Sysmex Corp.). More specifically, 1% NaCl
aqueous solution was prepared using primary sodium chloride, and filtrated
through a 0.45 µm pore size filter. To 50-100 ml of this solution was added
0.1-5 ml of a surfactant (preferably alkylbenzene sulfonate) as a dispersing
agent, followed by addition of 1-10 mg of sample. The mixture was then
sonicated for 1 minute using an ultrasonicator to prepare a dispersion with a
final particle concentration of 5,000-15,000/µL for measurement.
Measurement was made on the basis of a circle equivalent diameter - the
diameter of a circle having the same area as the 2D image of a toner particle


taken by a CCD camera. In view of resolution of the CCD camera,
measurement data were collected from particles with a circle equivalent
diameter of 0.6 µm or more.

Using a porosity measurement device shown in FIG. 3 the volume and
mass of toner packed under pressure of 10 kg/cm2 were measured, calculating
the porosity of toner particles with their specific gravity previously measured
taken into account.

The volume-average particle diameter (Dv) and number-average
particle diameter (Dn) of toner particles were measured using a particle size
analyzer (Multisizer II, Beckmann Coulter Inc.) at an aperture diameter of 100
µm, determining the particle size distribution (Dv/Dn) of the toner particles.

Whether or not an inorganic oxide particle layer is present within 1
µm from the toner surface of a toner particle was determined by observing a
cross section of the toner particle using a transmission electron microscope
(TEM).
Table 1



"Small diameter SF-2": toner particles with a particle diameter of less than 4
µm
"Large diameter SF-2": toner particles with a particle diameter of 4 µm or
greater
Note that "particle diameter most abundant in the particle size distribution" is
the peak value (4 µm) in the number-based particle size distribution of the
toner particles.
It can be learned from Table 1 that the surface factor SF-2 is
correlated with the volume-average particle diameter (Dv).
- Preparation of Developer-
To 3 parts of each of the toners prepared in Examples 1 to 4 and
Comparative Examples 1 and 2 was added 97 parts of 100-200 mesh ferrite
carrier coated with silicone resin, and mixed together using a ball mill. In this
way two-component developers were prepared.


Each developer thus prepared was evaluated for the image uniformity,
transfer ratio, occurrence of uneven transfer, and removability.
For each developer, a halftone image was formed using an image
forming apparatus (MS2800, manufactured by Ricoh Company, Ltd.) and the
degree of surface roughness was visually evaluated based on the following
criteria:
A: Excellent (the halftone image surface is very smooth)
B: Good (though not as smooth as A, the halftone image surface is almost free
from roughness; no practical problem)
C: Bad (the halftone image surface is slightly rough; but still practically
acceptable)
D Poor (the halftone image surface is very rough; practically unacceptable)

For each developer, a black filled-in image (size = 15 cm by 15 cm,
average image density = 1. 38 or more as measured by a Macbeth reflection
densitometer) was formed using the image forming apparatus (MS2800,
manufactured by Ricoh Company, Ltd.) and its transfer ratio was calculated
from the following Equation (3):
Transfer ratio (%) = (the amount of toner particles transferred to a
recording medium / the amount of toner particles developed on a latent
electrostatic image bearing member) x 100 ... Equation (3)



For each toner, a black filled-in image was formed using the image
forming apparatus (MS2800, manufactured by Ricoh Company, Ltd.) and the
occurrence of uneven transfer was visually determined and the unevenness was
evaluated based on the following criteria:
A: Excellent (no unevenness)
B: Good (little unevenness; no practical problem)
C: Bad (slight unevenness; still practically acceptable)
D: (much unevenness; practically unacceptable)

The presence of streaky marks on the photoconductor due to cleaning
trouble after image formation was visually determined and evaluated based on
the following criteria:
A: Excellent (no streaky marks on the photoconductor)
B: Good (one or two very thin, streaky marks that are barely recognized by
visual inspection; but no practical problem)
C: Bad (a few streaky marks that can be visually recognized; but practically
acceptable)
D: Poor (a number of discrete streaky marks that can be visually recognized;
practically unacceptable)



FIG. 9A is a picture showing laminated toner particles of Example 1
developed on a photoconductor, and FIG. 9B is a picture showing laminated
toner particles of Comparative Example 2 developed on a photoconductor.
As shown in FIG. 9A, the toner particles prepared in Example 1 -
spherical particles - are not scattered so much and the height of the toner
laminate constituting an image is small. The toner particles of Comparative
Example 2 shown in FIG. 9B, by contrast, are scattered so much and the height
of the toner laminate constituting an image is large. The image densities of the
two images in Example 1 and Comparative Example 2 were both 1.3.
The results shown in Table 2 and FIGS. 9A and 9B reveal that toners
of Examples 1 to 4 have more excellent image density and removability than
toners of Comparative Examples 1 and 2, and freed from transfer unevenness.
Industrial Applicability

The toner of the present invention can provide long-term removability
and high-definition images with reduced image layer thickness and densely-
packed toner particles. Thus, the toner of the present invention can be suitably
used for the formation of high-quality images. The developer, toner container,
process cartridge, image forming apparatus, and image forming method of the
present invention, all of which use the toner of the present invention, can be
suitably used for the formation of high-quality images.

WE CLAIM :
1. A toner comprising:
a toner material which comprises a binder resin and a colorant,
wherein the toner has a substantially spherical shape with
irregularities on its surface, and
wherein a surface factor SF-1 represented by the following Equation
(1) that represents the sphericity of toner particles is 105 to 180, a surface
factor SF-2 represented by the following Equation (2) that represents the
degree of surface irregularities of the toner particles is correlated with the
volume-average diameter of the toner particles, and the toner particles have an
inorganic oxide particle-containing layer within 1 µm from their surfaces.
SF-1 = [(MXLNG)2/AREA] x (100π/4) ... Equation (1)
where MXLNG represents the maximum length across a two-
dimensional projection of a toner particle, and AREA represents the area of the
projection
SF-2 = [(PERI)2/AREA] x (100/4Π) ... Equation (2)
where PERI represents the perimeter of a two-dimensional projection
of a toner particle, and AREA represents the area of the projection
2. The toner as claimed in claim 1, wherein the SF-1 is 115 to 160 and
the SF-2 is 110 to 300.


3. The toner as claimed in one of claims 1 to 2, wherein the difference
between the SF-2 of toner particles whose particle diameter is smaller than the
most abundant toner particle diameter in a particle size distribution and the SF-
2 of toner particles whose particle diameter is equal to or larger than the most
abundant toner particle diameter in the particle size distribution is 8 or greater.
4. The toner as claimed in any one of claims 1 to 3, wherein the
inorganic oxide particle-containing layer comprises silica.
5. The toner as claimed in any one of claims 1 to 4, wherein the volume-
average particle diameter is 3 µm to 10 µm.
6. The toner as claimed in any one of claims 1 to 5, wherein the ratio of
the volume-average particle diameter (Dv) to the number-average particle
diameter (Dn), (Dv/Dn), is 1.00 to 1.35.
7. The toner as claimed in any one of claims 1 to 6, wherein the
proportion of toner particles having a circle equivalent diameter, the diameter
of a circle having the same area as the projection of toner particle, of 2 µm is
20% or less on a number basis.
8. The toner as claimed in any one of claims 1 to 7, wherein the porosity


of the toner particles under pressure of 10 kg/ cm2 is 60% or less.
9. The toner as claimed in any one of claims 1 to 8, wherein the toner is
produced by emulsifying or dispersing a toner material solution or a toner
material dispersion in an aqueous medium to form toner particles.
10. The toner as claimed in claim 9, wherein the toner material solution or
toner material dispersion comprises an organic solvent, and the organic solvent
is removed upon or after production of toner particles.
11. The toner as claimed in one of claims 9 and 10, wherein the toner
material comprises an active hydrogen group-containing compound and a
polymer capable of reacting with the active hydrogen group-containing
compound, and toner particles are produced by reaction of the active hydrogen
group-containing compound with the polymer to produce an adhesive base
material which the toner particles comprise.
12. The toner as claimed in claim 11, wherein the toner material
comprises an unmodified polyester resin and the mass ratio of the polymer
capable of reacting with the active hydrogen group-containing compound to
the unmodified polyester resin (polymer / unmodified polyester resin) is 5/95
to 80/20.


13. A developer comprising a toner as claimed in any one of claims 1 to 12.
14. The developer as claimed in claim 13, wherein the developer is any one of a
one-component developer and a two-component developer.
15. A toner container comprising a toner as claimed in any one of claims 1 to
12.
16. An image forming method comprising:
forming a latent electrostatic image on a latent electrostatic image bearing
member;
developing the latent electrostatic image by use of a toner as claimed in any
one of claims 1 to 12 to form a visible image;
transferring the visible image to a recording medium; and
fixing the transferred visible image to the recording medium.

Documents:

02242-kolnp-2006 abstract.pdf

02242-kolnp-2006 claims.pdf

02242-kolnp-2006 correspondence others.pdf

02242-kolnp-2006 correspondence-1.2.pdf

02242-kolnp-2006 description(complete).pdf

02242-kolnp-2006 drawings.pdf

02242-kolnp-2006 form-1.pdf

02242-kolnp-2006 form-18.pdf

02242-kolnp-2006 form-3.pdf

02242-kolnp-2006 form-5.pdf

02242-kolnp-2006 international publication.pdf

02242-kolnp-2006 international search authority report.pdf

02242-kolnp-2006 pct form.pdf

02242-kolnp-2006 pct others document.pdf

02242-kolnp-2006 priority document.pdf

02242-kolnp-2006-assignment.pdf

02242-kolnp-2006-correspondence-1.1.pdf

02242-kolnp-2006-form-3-1.1.pdf

02242-kolnp-2006-priority document-1.1.pdf

2242-KOLNP-2006-ABSTRACT 1.1.pdf

2242-KOLNP-2006-AMANDED CLAIMS.pdf

2242-kolnp-2006-assignment.pdf

2242-KOLNP-2006-CORRESPONDENCE 1.2.pdf

2242-kolnp-2006-correspondence.pdf

2242-KOLNP-2006-DESCRIPTION (COMPLETE) 1.1.pdf

2242-KOLNP-2006-DRAWINGS 1.1.pdf

2242-kolnp-2006-examination report.pdf

2242-KOLNP-2006-FORM 1 1.1.pdf

2242-kolnp-2006-form 13-1.1.pdf

2242-KOLNP-2006-FORM 13.pdf

2242-kolnp-2006-form 18-1.1.pdf

2242-KOLNP-2006-FORM 2.pdf

2242-KOLNP-2006-FORM 3 1.1.pdf

2242-kolnp-2006-form 3.pdf

2242-kolnp-2006-form 5.pdf

2242-KOLNP-2006-FORM-27.pdf

2242-kolnp-2006-gpa-1.1.pdf

2242-KOLNP-2006-GPA.pdf

2242-kolnp-2006-granted-abstract.pdf

2242-kolnp-2006-granted-claims.pdf

2242-kolnp-2006-granted-description (complete).pdf

2242-kolnp-2006-granted-drawings.pdf

2242-kolnp-2006-granted-form 1.pdf

2242-kolnp-2006-granted-form 2.pdf

2242-kolnp-2006-granted-specification.pdf

2242-kolnp-2006-others-1.1.pdf

2242-KOLNP-2006-OTHERS.pdf

2242-KOLNP-2006-PA.pdf

2242-KOLNP-2006-PETITION UNDER RULE 137.pdf

2242-kolnp-2006-reply to examination report-1.1.pdf

2242-KOLNP-2006-REPLY TO EXAMINATION REPORT.pdf

abstract-02242-kolnp-2006.jpg


Patent Number 247523
Indian Patent Application Number 2242/KOLNP/2006
PG Journal Number 16/2011
Publication Date 22-Apr-2011
Grant Date 13-Apr-2011
Date of Filing 08-Aug-2006
Name of Patentee RICOH COMPANY, LTD.
Applicant Address 3-6, NAKAMAGOME 1-CHOME, OHTA-KU, TOKYO
Inventors:
# Inventor's Name Inventor's Address
1 NAKAYAMA, SHINYA GRAND RIVER AVENUE 201, 1714-10, AZA HINOGUCHI, SHIMOKANUKI, NUMAZU-SHI, SHIZUOKA 410-0822
2 UTSUMI, TOMOKO 2349, KADOSAWABASHI, EBINA-SHI, KANAGAWA 243-0426
3 IWAMOTO, YASUAKI 14-18, ICHIMICHI-CHO, NUMAZU-SHI, SHIZUOKA 410-0866
4 KOTSUGAI AKIHIRO 3135-15, SHIMOKANUKIZENDAYU, NUMAZU-SHI, SHIZUOKA 410-0822
5 NAKAJIMA, HISASHI CORPO UEHARA, 1-17-1 NUMAKITA-CHO, NUMAZU-SHI, SHIZUOKA 410-0058
6 ASAHINA YASUO INAMO HEIGHTS 205, 14-36, WAKABA-CHO NUMAZU-SHI, SHIZUOKA 410-0059
7 UCHINOKURA, OSAMU SUNRISE OTSUKA 103-1069-1, OTSUKA, NUMAZU-SHI, SHIZUOKA 410-0306
8 ISHII, MASAYUKI PARK HILLS OOKA 205, 995-1, OOKA, NUMAZU-SHI, SHIZUOKA 410-00222
9 ICHIKAWA, TOMOYUKI DAIROKUSUMIKA BUILDING 206, 115, SUENAGA-CHO, TAKATSU-KU, KAWASAKI-SHI, KANAGAWA 213-0013
10 SAKATA KOICHI TAKASHIMAHONCHO M'S 503,2-21 TAKASHIMAHONCHO, NUMAZU-SHI, SHIZUOKA 410-0055
11 IWATSUKI, HITOSHI GREEN GRASS 102, 7-32, HONTA-MACHI, NUMAZU-SHI, SHIZUOKA 410-0004
12 SUGIURA, HIDEKI 837-16, MIYAJIMA, FUJI-SHI, SHIZUOKA 416-0945
13 TOMITA MASAMI PASCO GRAND MASION SHINNUMAZU 302, 19-1, SHINJUKU-CHO, NUMAZU-SHI, SHIZUOKA 410-0048
14 MOCHIZUKI, SATOSHI ANGEL HEIM OKAISSHIKI 2-601, 27-1, OKISSIKI, NUMAZU-SHI, SHIZUOKA 410-0012
PCT International Classification Number G03G9/08; G03G9/087
PCT International Application Number PCT/JP2005/000876
PCT International Filing date 2005-01-24
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2004-026233 2004-02-03 Japan