Title of Invention

RECORDING INK, INK/MEDIA SET, INK CARTRIDGE, INKJET RECORDING METHOD AND INKJET RECORDING APPARATUS

Abstract To provide a recording ink which contains at least a water-dispersible colorant, a water-dispersible resin, a wetting agent, a surfactant and water, wherein the content of the wetting agent in the recording ink is in the range of from 20 % by mass to 35 % by mass, the total solid content of the water-dispersible colorant and the water-dispersible resin in the recording ink is in the range of from 12 % by mass to 40 % by mass, the water-dispersible resin contains fluorine resin particulates, and the ratio A:B, where A is the solid content of the water-dispersible resin in the recording ink and B is the solid content of a pigment contained in the water-dispersible colorant in the recording ink, is in the range of 0.5 to 8.
Full Text DESCRIPTION
RECORDING INK, INK/MEDIA SET, INK CARTRIDGE, INKJET
RECORDING METHOD AND INKJET RECORDING APPARATUS
Technical Field
The present invention relates to a recording ink and an ink/media set
which are suitable for inkjet recording, as well as an ink cartridge, an
inkjet recording method and an inkjet recording apparatus which use the
recording ink and the ink/media set.
Background Art
Inkjet recording apparatuses are known as a type of image recording
apparatuses used in, for example, printers, facsimile machines and
photocopiers. Such inkjet recording apparatus records images by
ejecting ink on a recording medium. Because of its uncomplicated image
forming process, the inkjet recording apparatus itself can be easily
simplified. Moreover, the image forming process of the inkjet recording
apparatus dose not require heating the recording medium, and thus it can
save energy consumption, and thus it is desirable for the environment.
It also has many advantages such as capability of quick recording of
high-resolution images, low running cost, low noise level and capability of
using a variety of color inks for recording images having a wide color
gamut.
Commonly used inks for the inkjet recording apparatus are
water-based inks containing a colorant, wetting agents such as glycerine,

penetrating agents for controlling permeability of ink to recording paper,
surfactants and other additives.
In the inkjet recording method, images are recorded on a recording
medium from such liquid water-based ink absorbed on the recording
medium. For this mechanism of forming images, variety of inkjet paper
having better ink absorbency and capability of fixing and protecting
coloring components has been developed. In terms of cost, however, as
inkjet paper is produced by applying multiple coatings on a paper base,
its production cost is high. And further, due to the large amount of
chemical agents contained inkjet paper, it has a poor recyclability
compared with regular paper. Thus, inkjet inks that can record high
quality images not only on inkjet paper but also on regular paper have
been desired.
The obstacle to forming high quality images on regular paper is that
is has a poorer ink absorbency than inkjet paper and it dose not provide
surface coatings suitable to accept inkjet ink. Thus, it is important to
solve the following problems to achieve high quality images on regular
paper, the problems include (1) occurrence of feathering (2) occurrence of
bleeding (3) reduction in image density (4) degradation of color gamut (5)
degradation of water resistance (6) degradation of light resistance (7)
degradation of gas resistance (8) degradation of ink fixation characteristic,
and (9) passing through to the other side of a recording medium.
In recent years, pigments having better dispersibility and smaller
particle diameters have been developed, and such pigments have been

started to be used in many inkjet inks. In addition to conventional
approaches (including adding surfactants and/or water-soluble resins) to
improve the dispersibility of pigments, methods of surface modification,
including oxidation treatment on the surface of pigment particles,
sulfonation treatment and graft polymerization, have been tried for
obtaining hydrophilicity in the pigments to thereby improve dispersion
stability thereof. Such pigments can solve (5), (6) and (7) of the above
mentioned problems, however, there still exist problems in reliability of
inks using the pigments that, because of poor density and color gamut of
the pigments compared with dyes, the inks have poorer ejection stability,
long term storage stability and redispersability than inks using dyes.
Thus, the reliability, density and color gamut of the inks using the
pigments have been important problems to be solved. In order to solve
those problems, many techniques using colored polymer particles,
particularly using emulsioned particles of a polyester or vinyl polymer in
inks for inkjet recording have been proposed. Examples of such inks
include those disclosed in Patent Literature 1 and non-Patent Literature
1. Examples of such inks further include those containing dispersed
compositions of a water-insoluble resin which internally contains a
colorant. In addition, it is commonly known that conventional inks
using organic pigments as colorants can provide better image density and
better color reproducibility on regular paper than conventional pigment
inks using water-soluble dispersants.
Conventionally, techniques to obtain suitable permeability to paper

in inks have been studied to thereby prevent ink from causing feathering
and bleeding and from passing through to the other side of a recording
medium, and to improve image density and color gamut. For example, a
commercial available ink for inkjet recording has a surface tension of
lower than 35 mN/m, and thereby the ink has a high permeability to
paper. Such high permeable inks can effectively prevent the occurrences
of bleeding and have a good drying characteristic on regular paper.
However, the inks tend to cause feathering and record images with
insufficient density and images/characters with vagueness.
On the other hand, some commercial available inks have a surface
tension of higher than 35 mN/m, and thereby the inks have a slow
permeability to paper. Such slow permeable ink slowly permeates into
paper to enable it to be accumulated on the surface area of paper. Thus,
it can effectively prevent the occurrence of feathering, improve image
density and color gamut and prevent it from passing through to the other
side of paper. The disadvantages of such low permeable ink are that,
because of its low permeability, the drying characteristic drastically
degrades on regular paper, and it results in degradation of ink fixation
characteristics and causing bleeding on multi-colored images.
Thus, an ink-set which combines a low permeable ink with a high
permeable ink has been studied. Such technique can prevent inter-color
bleeding, and thus it enables to record high quality images. However,
when such ink is used in two-sided printing, it brings low productivity
because it requires a long drying time. Thus, some commercial available

recording apparatuses are equipped with a heater to reduce the drying
time of ink. In such apparatuses, paper is heated with the heater before
and after ink is placed thereon. Examples of such apparatuses include
the one disclosed in Patent Literature 2. Such disclosed apparatus,
however, tends to be large and complicated as it contains a heater. And
further, it consumes great amount of energy for heating paper. Thus, the
apparatus has no advantages which an inkjet recording apparatus
supposed to have.
In addition to the above-stated inks for inkjet recording, many
attempts have been made to develop inks which not only have reliability
and but also can record high quality images. For example, many inks
having as low a viscosity as possible have been developed to prevent them
from blocking the nozzles of the inkjet head. Patent Literature 3
proposes an ink that prevents the aggregation of pigment particles in
order to prevent the ink from being spread, and can further prevent it
from causing the generation fo blank spots in images. Patent Literature
3 suggests such ink can be obtained by adjusting the change in its
viscosity within 10 times higher than initial viscosity and particle
diameters within 3 times larger than initial diameters when the ink is
concentrated 2 times. With this technique, however, it is difficult to
record high quality images on regular paper with the proposed ink.
In the ink disclosed in Patent Literature 4, the remnant of the ink
after its volatile compositions has evaporated is liquid, and the viscosity
of the ink in that state is within 10 times higher than the initial viscosity.

The disclosed ink has an excellent reliability, while the ink itself is a dye
ink which is disadvantageous in terms of image quality compared with a
pigment ink.
Patent Literature 5 discloses an ink whose viscosity increases within
600 times after water evaporates therefrom under 60 °C. The disclosed
ink balances its durability with both reliability and image quality of the
ink by adding a water-soluble polymer, while the ink itself is also a dye
ink, and thus has a poor water resistance.
Patent Literature 6 suggests that an ink that can record high quality
images requires its viscosity be adjusted in the range of from 5 mPa.s to
15 mPa.s. The disclosed technique suggests adjusting the initial
evaporation rate of the ink to improve its reliability, and further suggests
adding a certain sort of compounds as viscosity adjusters to obtain a
desired viscosity in the ink. The disclosed technique thus can solve (3)
and (4) of the above-stated problems. The problem of the disclosed
technique is that the uniformity in the particle diameter of the used
pigment is not taken into consideration. Thus, although it states that
the ink has an excellent reliability after left 24 hours, the ink may not be
reliable enough after left longer period of time, depending on the
configuration of a head and the diameter of nozzles for ejecting ink drops.
As described above, although it is necessary that inks have a high
viscosity for rapidly forming high quality images, it is difficult to obtain
reliability on such high viscosity inks.
Patent Literatures 7 and 8 each propose adding a water-insoluble

resin into a pigment ink to achieve better image quality. Patent
Literature 9 proposes an ink that can improve the quality of images
formed on regular paper. The disclosed ink has the ratio of a pigment to
a resin emulsion in the range of 1-0.1 to 1-1 and an average diameter of a
coloring component in the range of 0.3 urn to 1.2 µm. Such inks
containing the resin emulsion can prevent the occurrences of bleeding and
feathering, while it cannot provide a sufficient image density and
reliability as an ink for inkjet recording.
Patent Literature 10 proposes an ink containing a water insoluble
resin and having its minimum film formation temperature at 40 °C or
higher. Patent Literature 11 proposes an ink having an emulsion
diameter of 50 nm or smaller. In those proposed techniques, however,
the reliability and image quality are still insufficient and yet to be
improved.
Patent Literature 12 discloses an ink containing a pigment,
saccharides or derivatives thereof, a polyol having 5 or more hydroxyl
groups and a resin emulsion. It states that the ink can record clearer
images/characters. But the ink has a low permeability to regular paper,
and thus has problems in, for example, preventing inter-color feathering,
bleeding and degradation in ink fixation characteristic and ink drying
time.
Patent Literature 13 proposes an ink having solid contents of a water
dispersible resin and a selfdispersible pigment in the range of 1.0 % by
mass to 16 % by mass. It states that the ink can provide better image

quality on regular paper. Although the disclosed ink can provide better
water resistance than dye inks, its water resistance is still insufficient to
be used with maker pens which are commonly used on regular paper.
Adding a dispersed pigment and a resin emulsion into inks increases
the solid content thereof and thus increases the viscosity of the ink. This
method to increase ink viscosity has been studied as a means to improve
characteristics of ink. Patent Literatures 12 and 14 propose inks in
which resin forming micelle-aggregate is added to increase the solid
content thereof, while changes in the change in the viscosity of the inks is
kept at a small increase. The proposed inks still have an insufficient
permeability to regular paper, and thus the quality of images recorded
with the ink is still to be improved. The permeability to paper is
explained by capillarity represented by Lucas-Washburn equation.
Higher viscosity of an ink requires the ink have a lower surface tension
and the contact angle of ink drops to paper be arranged in order to obtain
sufficient permeability of the ink.
Patent Literatures 15 and 16 propose using polyalcohol alkylether in
an ink with a high solid content to increase its permeability. In the
proposed inks, however, the viscosity increases accompanied by increase
in the solid content, and thus sufficient permeability may not be obtained
in the inks, resulting in the degradation of image quality.
That even small amounts of silicone surfactants and/or fluorinated
surfactants can increase the permeability of an ink is known, and many
attempts have been made to apply this means. For example, Patent

Literatures 17 and 18 each propose an inkjet ink containing a fluorinated
surfactant. And further, Patent Literatures 19 and 20 each propose an
ink having a dispersed pigment and a fluorinated surfactant. Patent
Literature 21 proposes an ink which contains a fluorinated surfactant
and polymer particulates containing either a water-insoluble and/or
hardly-soluble coloring material, and has polymer emulsion and a
viscosity of 5 mPa.s or more.
However, color phase changes with increase of the content of the
solidified pigments in those proposed inks. Thus a high concentration
pigment will not provide desirable color phase, while a self-dispersible
pigment will not provide sufficient water resistance and ink fixation
characteristic.
[Patent Literature 1]: Japanese Patent Application Laid-Open
(JP-A) No. 2000-191972
[Patent Literature 2]: JP-A No. 5569464
[Patent Literature 3]: JP-A No. 2002-337449
[Patent Literature 4]: JP-A No. 2000095983
[Patent Literature 5]: JP-A No. 09-111166
[Patent Literature 6]: JP-A No. 2001-262025
[Patent Literature 7]: JP-A No. 55-157668
[Patent Literature 8]: Japanese Patent Application Publication
(JP-B) No. 62-1426
[Patent Literature 9]: JP-A No. 04332774
[Patent Literature 10]: Japanese Patent (JP-B) No. 2867491

[Patent Literature 11]: JP-A No. 04-18462
[Patent Literature 12]: JP-B No. 3088588
[Patent Literature 13]: JP-A No. 2004-35718
[Patent Literature 14]: JP-A No. 200499800
[Patent Literature 15]: JP-A No. 2004-155867
[Patent Literature 16]: JP-A No. 2004203903
[Patent Literature 17]: JP-B No. 2675001
[Patent Literature 18]: JP-B No. 2667401
[Patent Literature 19]: JP-A No. 04-211478
[Patent Literature 20]: JP-A No. 2003-277658
[Patent Literature 21]: JP-A No. 2003-226827
[Non-Patent Literature 1]: "Kinousei ganryou no gijutu to ouyou"
published by CMC Publishing CO., LTD.
Disclosure of Invention
An object of the present invention is to solve the forementioned
problems, and to provide a recording ink and an ink/media set that enable
recording a high quality image on regular paper, and particularly,
preventing the generation of blank spots. And further, the recording ink
can record an image having an excellent image density, saturation and
image durability characteristics which include water resistance and light
resistance, can provide fast-drying images and prevent the ink from
causing beading even on regular printing paper having poor ink
absorbency, has fast drying speed, and can be used in fast recording
processes and stably ejected from nozzles. The present invention is also

to provide an ink cartridge using/used in the recording ink and the
ink/media set, an inkjet recording method and an inkjet recording
apparatus.
The means for solving the forementioned problems are as follows^
. A recording ink, including:
a water-dispersible colorant,
a water-dispersible resin,
a wetting agent,
a surfactant, and
water,
wherein the content of the wetting agent in the recording ink is in the
range of from 20 % by mass to 35 % by mass,
the total solid content of the water-dispersible colorant and the
water-dispersible resin in the recording ink is in the range of from 12 %
by mass to 40 % by mass,
the water-dispersible resin contains fluorine resin particulates, and
the ratio A-B, where A is the solid content of the water-dispersible
resin in the recording ink and B is the solid content of a pigment
contained in the water-dispersible colorant in the recording ink, is in the
range of 0.5 to 8.
. The recording ink according to , wherein the
water-dispersible colorant contains at least a hydrophilic group at its
surface and is a pigment that is water-dispersible under the absence of a
dispersant.

. The recording ink according to , wherein the
water-dispersible colorant is a polymer emulsion that is composed of
polymer particulates containing a water-insoluble and/or hardly-soluble
coloring material.
. The recording ink according to , wherein
the water-dispersible colorant is a dispersed pigment containing a
pigment, a pigment dispersaht and a polymer dispersion stabilizer, and
the polymer dispersion stabilizer is any one of alphaolefin/maleic
anhydride copolymer represented by the following structural formula (1),
styrene-(meth)acryl copolymers, water-soluble polyurethane resins and
water-soluble polyester resins.

Where R represents an alkyl group, and n represents an integer of 30 to
100.
. The recording ink according to , wherein
the polymer dispersion stabilizer has a weight average molecular
weight of 20,000 or lower and an acid value of 40 mgKOH/g to 400
mgKOH/g, and is dissolved in any one of an alkali solution and alkali
water-solution having an alkalinity value equivalent to or higher than the
acid value to be used.
. The recording ink according to one of and , wherein the

pigment dispersant is an anion surfactant or a nonionic surfactant having
an HLB value of 10 to 20.
. The recording ink according to , wherein the nonionic
surfactant is any one of polyoxyethylene-β-naphthylether,
polyoxyethylene laurylether and polyoxyethylene styrene phenylether.
. The recording ink according to any one of to , wherein
the fluorine resin particulates contain a fluoroolefin unit and have a
minimum film forming temperature of 30 °C or lower.
. The recording ink according to any one of to , wherein
the wetting agents is at least any one selected from glycerins, diethylene
glycol, triethylene glycol, l,3butanediol, 3-methyl-l,3-butanediol,
2pyrrolidone and N-methyl-2-pyrrolidone.
. The recording ink according to any one of to , wherein
the surfactant includes at least one selected from silicone surfactants and
fluorine surfactants.
. The recording ink according to any one of to , wherein
the viscosity thereof at 25 °C is in the range of from 5 mPa.s to 20 mPa.s,
and the surface tension thereof is 35 mN/m or lower.
. An ink/media set, including:
the recording ink according to any one of to , and
a recording medium,
wherein the recording medium includes a base and a coating layer
which is provided on at least one surface of the base, and
the transfer amount of pure water to the recording medium,

measured with a dynamic scanning absorptometer, is in the range of from
2 ml/m2 to 35 ml/m2 at a contacting time of 100 ms and in the range of
from 3 ml/m2 to 40 ml/m2 when measured at a contacting time of 400 ms.
. An ink cartridge, including a container for housing the
recording ink according to any one of to .
. An inkjet recording method, including ejecting drops of the
recording ink according to any one of to by applying an impulse
thereto to record an image.
. The inkjet recording method according to , wherein the
impulse is at least any one selected from heat, pressure, vibration and
light.
. An inkjet recording apparatus, including a means for ejecting
drops of the recording ink according to any one of to by applying
an impulse thereto to record an image.
. The inkjet recording apparatus inkjet recording method
according to , wherein the impulse is at least any one selected from
heat, pressure, vibration and light.
. An ink recorded matter, including:
a recording medium and an image formed on the recording medium,
wherein the image is formed using the recording ink according to any
one of to.
. An ink recorded matter, including:
the recording medium of the ink/media set according to , and
an image formed on the recording medium, wherein the image is

formed using the recording ink of the. ink/media set according to .
The recording ink of the present invention contains at least a
water-dispersible colorant, a water-dispersible resin, a wetting agent, a
surfactant and water, wherein the content of the wetting agent in the
recording ink is in the range of from 20 % by mass to 35 % by mass, the
total solid content of the water-dispersible colorant and the
water-dispersible resin in the recording ink is in the range of from 12 %
by mass to 40 % by mass, the water-dispersible resin contains fluorine
resin particulates, and the ratio A-B, where A is the solid content of the
water-dispersible resin in the recording ink and B is the solid content of a
pigment contained in the water-dispersible colorant in the recording ink,
is in the range of 0.5 to 8.
The recording ink of the present invention can record a high quality
image on regular paper, and particularly, prevent the generation of blank
spots. And it also can record an image having an excellent image density,
saturation and durabilitis which includes water resistance and light
resistance, has fast drying speed, can be used in fast recording processes
and can be stably ejected from nozzles.
The ink can further record fast-drying images and prevent the ink
from beading even on regular printing paper which is a recording medium
having a poor ink absorbency, wherein the recording medium has a base
and a coating which is provided on at least one side of the base, the
transfer amount of pure water to the recording medium is in the range of
from 2 ml/m2 to 35 ml/m2 when measured at a contacting time of 100 ms

and with a dynamic scanning absorptometer, and the transfer amount of
pure water to the recording medium is in the range of from 3 ml/m2 to 40
ml/m2 when measured at a contacting time of 400 ms.
The ink/media set of the present invention contains the recording ink
of the present invention and a recording medium, wherein the recording
medium has a base and a coating which is provided on at least one side of
the base, the transfer amount of pure water to the recording medium is in
the range of from 2 ml/m2 to 35 ml/m2 when measured at a contacting
time of 100 ms and with a dynamic scanning absorptometer, and the
transfer amount of pure water to the recording medium is in the range of
from 3 ml/m2 to 40 ml/m2 when measured at a contacting time of 400 ms.
The ink/media set of the present invention can record a high quality
image on regular paper, and particularly, prevent the generation of blank
spots. And further, it can record an image having an excellent image
density, saturation and durability characteristics which include water
resistance and light resistance, has fast drying speed, can be used in fast
recording processes and can be stably ejected from nozzles.
The ink can further record fast-drying images and prevent the ink
from beading even on regular printing paper which is a recording medium
having poor ink absorbency, wherein the recording medium has a base
and a coating which is provided on at least one side of the base, the
transfer amount of pure water to the recording medium is in the range of
from 2 ml/m2 to 35 ml/m2 when measured at a contacting time of 100 ms
and with a dynamic scanning absorptometer, and the transfer amount of

pure water to the recording medium is in the range of from 3 ml/m2 to 40
ml/m2 when measured at a contacting time of 400 ms.
The ink cartridge of the present invention is a container for storing
the recording ink of the present invention. The ink cartridge is
preferably used in inkjet printers. The ink stored in the ink cartridge
can prevent the generation of blank spots on regular paper. And further,
it can record an image having an excellent image density, saturation and
image durability characteristics which include water resistance and light
resistance, can provide fast-drying images and prevent the ink from
causing beading even on gloss printing paper, has fast drying speed, can
be used in fast recording processes and can be stably ejected from nozzles.
The inkjet recording apparatus of the present invention contains at
least an ink ejection unit which applies energy to the recording ink of the
present invention to eject drops of the recording ink to thereby record
images. In the inkjet recording apparatus, the ink ejection unit applies
energy to the recording ink of the present invention to eject the ink drops
to thereby record images. Thus, when the recording apparatus is used
for recording images on regular paper, it can prevent the generation of
blank spots, and further can record images having an excellent image
density, saturation and image durability characteristics which include
water resistance and light resistance. And also it can provide
fast-drying images and prevent the ink from beading even on gloss
printing paper, has fast drying speed, can be used in fast recording
processes, can be stably ejected from nozzle, and can record images as

good quality as offset-printed matters.
The inkjet recording method of the present invention contains at
least an ink ejection step which applies energy to the recording ink of the
present invention to eject drops of the recording ink to thereby record
images. In the inkjet recording method, the ink ejection step applies
energy to the recording ink of the present invention to eject the ink drops
to thereby record images. Thus, when the recording method is used for
recording images on regular paper, it can prevent the generation of blank
spots, and further can record images having an excellent image density,
saturation and image durability characteristics which include water
resistance and light resistance. And also it can provide fast-drying
images and prevent the ink from beading even on gloss printing paper,
has fast drying speed, can be used in fast recording processes, can be
stably ejected from nozzle, and can record images as good quality as
offset-printed matters.
The ink recorded matter of the present invention is composed of a
recording medium and an image formed on the recording medium using
the recording ink of the present invention.
The ink recorded matter of the present invention is composed of a
recording medium of the ink/media set of the present invention and an
image formed on the recording medium using the recording ink of the
ink/media set of the present invention.
When the ink recorded matter of the present invention is regular
paper, it is possible to prevent the generation of blank spots, record

images having an excellent image density, saturation and image
durability characteristics which include water resistance and light
resistance, record fast-drying images even on gloss printing paper while
preventing its beading, achieve fast drying speed, can be used in fast
recording processes, can be stably injected from nozzles, and can record
images as good quality as offset-printed matters.
And further, it is possible to record fast-drying images and prevent
the ink from beading even on regular printing paper which is a recording
medium having poor ink absorbency, wherein the recording medium has a
base and a coating which is provided, on at least one side of the base, the
transfer amount of pure water to the recording medium is in the range of
from 2 ml/m2 to 35 ml/m2 when measured at a contacting time of 100 ms
and with a dynamic scanning absorptometer, and the transfer amount of
pure water to the recording medium is in the range of from 3 ml/m2 to 40
ml/m2 when measured at a contacting time of 400 ms.
Brief Description of Drawings
FIG. 1 is a schematic view showing one example of an ink cartridge of
the present invention.
FIG. 2 is a schematic view showing one example of a case and the ink
cartridge of FIG. 1 contained therein.
FIG. 3 is a perspective view exemplarily showing an inkjet recording
apparatus with a cover for an ink cartridge-loading section opened.
FIG. 4 is a schematic view showing one example of the entire
configuration of an inkjet recording apparatus.

FIG. 5 is a magnified view schematically showing one example of the
inkjet head in the present invention.
Best Mode for Carrying Out the Invention
(Recording Ink)
The recording ink of the present invention contains at least a
water-dispersible colorant, a water-dispersible resin, a wetting agent, a
surfactant, water and a penetrating agent, and it further contains other
components in accordance with necessity.
In the present invention, the water-dispersible resin contains
fluorine resin particulates, and the ratio A:B, where A is the solid content
in the recording ink and B is the solid content of a pigment contained in
the water-dispersible colorant in the recording ink, is in the range of 0.5
to 8, and preferably is in the range of 2 to 6. When the ratio is in the
ranges, the ink fixation characteristic and color gamut are improved.
The solid content of the water-dispersible resin is preferably 3, 4 or more
times higher than that of the pigment for improving the color gamut and
the image density, while it is preferably within 8 times higher as the
marginal improvements in the color gamut and image density diminish
over the range. And when the ratio, A/B, is less than 0.5, ink fixation
characteristic may be degraded in the image portions and/or ink may pass
through to the other side of paper.
The total content of the water-dispersible colorant and
water-dispersible resin to the total mass of the recording ink is preferably
in the range of from 12 % by mass to 40 % by mass, and more preferably

in the range of from 15 % by mass to 35 % by mass. When the total
content is in those ranges, the ink can record clear images/characters.
When the total content is less than 12 % by mass, drying characteristics
of the ink may be degraded on paper, and further, clear images/characters
may not be recorded on regular paper. And when it is more than 40 % by
mass, the ink may easily block the nozzles, causing ejection failures.
Extracting only the colorant and waterdispersible resin from the ink
is an example of means to measure the solid contents of the
water-dispersible colorant, the pigment of the waterdispersible colorant
and the water-dispersible resin. And when a pigment is used as the
colorant, the proportion of the colorant and waterdispersible resin can be
determined based on the mass reduction rate obtained by a thermal mass
analysis. When the colorant is, for example, a pigment or a dye, and its
molecular structure is known, the solid content of the colorant can be
determined by the nuclear magnetic resonance analysis, or NMR. When
the colorant is, for example, an inorganic pigment contained in heavy
metal atom/molecular frame, a metal-containing organic pigment or a
metalcontaining dye, and its molecular structure is known, the solid
content of the colorant can be determined by the X-ray fluorescence
analysis, or XRF.

The waterdispersible colorant in the first structure is a pigment that
has at least a hydrophilic group on its surface and shows
water-dispersibility under the existence of no dispersant. Thus, the

pigment may be hereinafter called self-dispersible pigment.
The water-dispersible colorant in the second structure is a polymer
emulsion composed of polymer particulates containing a water-insoluble
and/or hardly-soluble colorant.
The water-dispersible colorant in the third structure is a dispersed
pigment containing a pigment, a pigment dispersant and a polymer
dispersion stabilizer, wherein the polymer dispersion stabilizer is at least
any one of selected from an alpha-olefin/maleic anhydride copolymer
represented by the following structural formula 1, styrene(meta)acryl
copolymer, water-soluble polyurethane resin and water-soluble polyester
resin.

Where R represents an alkyl group, and n represents an integer of 30 to
100.
- Pigment -
As the above-stated pigment, organic pigments and inorganic
pigments can be used. A dye can also be used as a pigment for adjusting
color tones, while the content of the dye should be limited within a range
in which durability of the ink will not degraded.
Examples of the inorganic pigments include titanium oxides, iron
oxides, calcium carbonates, barium sulfates, aluminium hydroxides,

barium yellow, cadmium red, chromium yellow and carbon blacks.
Among those organic pigments, the carbon black is preferable.
Examples of the carbon black include those produced by known methods
such as a contact method, a furnace method or a thermal method.
Examples of the organic pigments include azo pigments, polycyclic
pigments, dye chelates, nitro pigments, nitroso pigments and aniline
blacks. Among those organic pigments, the azo pigments and polycyclic
pigments are preferable. Examples of the azo pigments include azo
lakes, insoluble azo pigments, condensed azo pigments and chelate azo
pigments. Examples of the polycyclic pigments include phthalocyanine
pigments, perylene pigments, perinone pigments, anthraquinone
pigments, quinacridone pigments, dioxadine pigments, indigoid pigments,
thioindigoid pigments, isoindolinone pigments and quinophtalone
pigments. Examples of the dye chelates include basic dye chelates and
acidic dye chelates.
The color of the colorant is not particularly limited and can be
appropriately selected depending on the purpose. Examples thereof
include colorants used for an achromatic color and for variety of other
colors. These may be used alone or in combination.
Examples of colorants used for an achromatic color include carbon
blacks (C.I. pigment black 7) such as furnace blacks, lamp blacks,
acetylene blacks and channel blacks; metals such as copper, iron (C.I.
pigment black 11) and titanium oxide; and organic pigments such as
aniline black (C.I. pigment black 1).

Examples of colorants used for colors include C.I. pigment yellow 1, 3,
12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95,
97, 98, 100, 101, 104, 408, 109, 110, 117, 120, 128, 138, 150, 151, 153 and
183; C.I. pigment orange 5, 13, 16, 17, 36, 43, and 51, C. I. pigment red 1,
2, 3, 5, 17, 22, 23, 31, 38, 48:2 and 48:2 (permanent red 2B (Ca)), 48:3,
48:4, 49:1, 52:2, 53:1, 57:1 (brilliant carmin 6B), 60:1, 63:1, 63:2, 64:1, 81,
83, 88, 101 (iron oxide red), 104, 105, 106, 108 (cadmium red), 112, 114,
122 (quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178,
179, 185, 190, 193, 209 and 219; C.I. pigment violet 1 (rhodamine lake), 3,
5:1, 16, 19, 23, and 38, C.I. pigment blue 1, 2, 15 (copper phthalocyanine
blue), 15:1, 15:2, 15:3 (copper phthalocyanine blue), 16, 17:1, 56, 60, the
63; and C.I. pigment green 1, 4, 7, 8, 10, 17, 18, and 36.
The self-dispersible pigment in the first structure is a
surface-modified pigment to whose surface at least a hydrophilic group is
bound either directly or through another atom group. The surface is
modified by chemically binding a functional group (such as sulfone groups
or carboxyl groups) to the surface of the pigment or by a wet-oxidation
treatment using at least one of a hypohalous acid and a salt thereof. Of
pigments obtained by those methods, a water-dispersed pigment to whose
surface a carboxyl group is bound is particularly preferable. Such
surface-modified pigments to which the carboxyl group is bound not only
can improve the dispersion stability but also enable to record high quality
and clear images/characters and provide a recording medium after
printed with better water resistance.

An ink using the pigments is excellent in redispersibility after drying.
Thus, the ink will not block inkjet nozzles of an inkjet head even when the
ink is kept in an inkjet recording apparatus without being used for a long
time and water evaporates from ink existing around the nozzles. That is
to say, simply cleaning will be enough for maintaining the ability of the
inkjet head to record high quality images.
The volume average particle diameter (D50) of the self-dispersible
pigment in the ink is preferably in the range of from 0.01 urn to 0.16 µm .
For example, self-dispersible carbon blacks having ionic property and
charged anionically or cationically are preferably used.
Examples of anionic hydrophilic group include -COOM, -SO3M,
-PO3HM, -PO3M2, -SO2NH2 and -SO2NHCOR (where M represents a
hydrogen atom, an alkali metal, an ammonium or an organic ammonium).
In the formulas, R represents an alkyl group having 1 to 12 carbon atoms,
a phenyl group which may have substituents, or a naphthyl group which
may have substituents. With those groups, it is preferable to use color
pigments to whose surface -COOM or -SO3M is bound.
In the above-stated hydrophilic groups, M may be an alkali metal
such as lithium, sodium or potassium. It may be an organic ammonium
such as mono- and/or trimethyl ammonium, mono- and/or tri-ethyl
ammonium or mono- and/or trrmethanol ammonium. The methods of
obtaining the color pigment anionically charged include introducing
-COONa onto the surface of the color pigment. Means to introduce
-COONa include oxidation-treatment with sodium hypochlorite,

sulfonation and reacting diazonium salt.
As the cationic hydrophilic group, quaternary ammonium groups are
preferable. The quaternary ammonium groups shown below are more
preferable, and in the present invention, any one of the quaternary
ammonium groups whose surface is bound to the surface of a carbon black
is preferably used as a coloring material.

The methods of producing the cationic selfdispersible carbon
blacks to which the hydrophilic group is bound are not particularly
limited, and can be appropriately selected depending on the purpose.

Examples thereof include treating the carbon black with
3-anuno-Nethylpyridium bromide as a means for binding N-ethylpyridyl
group represented by the following structural formula.

The hydrophilic group may be bound to the surface of the carbon
black through another atomic group. Examples of the other atomic
group include alkyl groups having 1 to 12 carbon atoms, phenyl groups
which may have a substituent and naphthyl groups which may have a
substituent. Specific examples of the hydrophilic group bound to the
carbon black surface through the other atomic group include -C2H4COOM
(where M represents an alkali metal or quaternary ammonium),
-PhSO3M (where Ph represent a phenyl group, M represents an alkali
metal or quaternary ammonium), and -C5H10NH3+.
The waterdispersible colorant in the second structure can be, in
addition to the above-stated pigments, a polymer emulsion composed of
polymer participates containing a pigment. The polymer emulsion is a
polymer participate in which a pigment is enclosed and/or a polymer
particulate to whose surface a pigment is adhered. In such case, not all
the pigment is necessarily enclosed and/or adhered, and the pigment may
be dispersed in the emulsion within a certain amount in which the effect
of the present invention will not be spoiled. The polymers for forming
the polymer emulsion include vinyl polymers, polyester polymers and
polyurethane based polymers. The polymers particularly preferably

used are vinyl polymers and polyester polymers. Those polymers are
disclosed in, for example, JP-A No. 200053897 and JPA No.
2001139849.
A complex pigment composed of particles of a known
organic/inorganic pigment and covered with an organic pigment or carbon
black can be preferably used. Such complex pigments can be obtained by,
for example, extracting an organic pigment under the existence of
particles of an inorganic pigment or by a mechanochemical method in
which inorganic pigment and organic pigment are mechanically
mixed/pulverized. Upon necessity, a layer of organosilane compound
composed of polysiloxane or alkylsilane can be provided in between a
layer of an inorganic pigment and a layer of organic pigment to enhance
the binding of the two layers.
Examples of the organic pigment include black pigments such as
aniline black; and collar pigments such as anthraquinones,
phthalocyanine blues, phthalocyanine greens, diazos, monoazos,
pyranetrons, perylenes, heterocyclic yellows, quinacridones and
(thio)indigoides. Among those, pigments of carbon blacks,
phthalocyanines, quinacridones, monoazo yellows, disazo yellows and
heterocyclic yellows are particularly preferable in terms of color gamut.
Representative examples of the phthalocyanine blues include copper
phthalocyanine blue and derivatives thereof (C.I. pigment blue 15:3, 15:4)
and aluminum phthalocyanine. Examples of the quinacridones include
C. I. pigment orange 48; C. I. pigment orange 49; C. I. pigment red 122; C.

I. pigment red 192; C. I. pigment red 202; C. I. pigment red 206; C. I.
pigment red 207; C. I. pigment red 209; C. I. pigment violet 19; and C. I.
pigment violet 42. Representative examples of the monoazo yellows
include C. I. pigment yellow 74, C. I. pigment yellow 109, C. I. pigment
yellow 128 and C. I. pigment yellow 151. Representative examples of the
disazo yellows include C. I. pigment yellow 14, C. I. pigment yellow 16,
and C. I. pigment yellow 17. Representative examples of the heterocyclic
yellows include C. I. pigment yellow 117 and C. I. pigment yellow 138.
Other appropriate pigment can be found in The Color Index, the third
edition (published by the Society of Dyers and Colorists, 1982).
Examples of the inorganic pigments include titanic dioxides, silicas,
aluminas, iron oxides, iron hydroxides and tin oxides. In terms of the
shape of those particles, smaller aspect ratio is more preferred, and the
particles are most preferably spherical. When a coloring material is
adhered to the surface, the color of the inorganic pigment is preferably
transparent or white. When a black colorant is adhered to the surface, a
black inorganic pigment may be used. The primary particle diameter of
the particles of the inorganic pigment is preferably 100 nm or smaller,
and more preferably in the range of 5 nm to 50 nm.
The mass ratio of the particles of the inorganic pigment and either
the organic pigment (or a colorant) or a carbon black as a coloring
material is preferably in the range of 3:1 to 1:3, and more preferably in
the range of 3:2 to 1:2. When the amount of the coloring material is
insufficient, the color gamut and coloring ability may be degraded. And

when an excessive amount of the colorant is contained, the clarity and
color tones may be degraded.
Examples of such particles of inorganic pigment as a coloring
material, covered with an organic pigment or carbon black, include
silica/carbon black complex material, silica/phthalocyanine PB (15:3)
complex material, silica/disazo yellow complex material and
silica/quinacridone PR122 complex material (all manufactured by Toda
Kogyo Corporation). They are preferable because of their small average
primary diameter.
When a particle of an inorganic pigment, having a primary particle
diameter of 20 nm, is covered with an organic compound whose amount is
equal to the particle, the resulted pigment particle will have a primary
particle diameter of around 25 nm can be obtained. By using an
appropriate dispersant to disperse the particles with the primary
diameter, a fine pigment-dispersed ink composed of dispersed particles
having a diameter of 25 nm. In such complex pigment, not only the
organic pigment provided on the surface but also the inorganic pigment
covered with the thin organic layer having thickness of around 2.5 nm
affects the dispersed state. Thus, it is important to select a pigment
dispersant that can stably disperse both the organic and inorganic
pigments at the same time.
The waterdispersible colorant in the third structure is a dispersed
pigment which contains the inorganic pigment, organic pigment, complex
pigment, pigment dispersant and polymer dispersion stabilizer, wherein

the polymer dispersion stabilizer is preferably any one selected from an
alphaolefin/maleic anhydride represented by the following structural
formula 1, styrene(meta)acryl copolymer, water-soluble polyurethane
resin and water-soluble polyester resin.

Where R represents an alkyl group, and n represents an integer of 30
to 100. The alkyl group preferably has 6 to 25 carbon atoms, and more
preferably has 6 to 22 carbon atoms.
The polymer dispersion stabilizer is an effective means to stably
maintain the dispersed condition of the pigment uniformly dispersed in
water with the pigment dispersant. The alphaolefin/maleic anhydride,
styrene-(meta)acryl copolymer, water-soluble polyurethane resin and
watersoluble polyester resin represented by the structural formula 1 is
solid under room temperature and hardly dissolved in cold water. When
dissolved in an alkali solution or an alkali water-solution having an
alkalinity value equivalent to or higher than, or preferably 1.0 to 1.5
times higher than, the acid value of the copolymer/resin, they function as
a dispersion stabilizer.
By heating and mixing the mixture of the copolymer/resin and the
alkali solution/alkali water-solution, they can be easily dissolved in the
solution. When the alpha-olefin/maleic anhydride copolymer contains a

long olefin chain, it will not easily be dissolved and may generate an
undissolved matter. In such case, the effect thereof as a dispersion
stabilizer can be maintained by appropriately filtering out the
undissolved matter.
Examples of the base of the alkali solution or alkali water-solution
include hydroxides such as sodium hydroxide, potassium hydrate and
lithium hydroxide; basic substances such as ammonium, triethylamine
and morpholine; and alcohol amines such as tryethanolamine,
diethanolamine, N-methyldiethanolamine,
2-amino-2ethyl- 1,3-propanediol and.choline.
For the alp haolefin/maleic anhydride copolymer represented by the
structural formula 1, either those appropriately synthesized or
commercially available products may be used. Examples of the
commercially available products include TYP112, T-YP115, TYP114 and
TYP116 (all manufactured by SEIKO PMC Corporation).
For the styrene-(meta)acryl copolymer, either those appropriately
synthesized or commercially available products may be used. Examples
of the commercially available products include JC-05 (manufactured by
SEIKO PMC Corporation), and AEUFONUC-3900, ARUFONUC-3910
and ARUFONUC-3920 (all manufactured by Tbagosei Co., Ltd.).
For the water-soluble polyurethane resin, either those appropriately
synthesized or commercially available products may be used. Examples
of the commercially available products include TAKELAC®W-5025,
TAKELAC®W-6010 and TAKELAC®W-5661 (all manufactured by

MITSUI TAKEDA CHEMICALS, INC.).
For the water-soluble polyester resin, either those appropriately
synthesized or commercially available products may be used. Examples
of the commercially available products include NICHEGO POLYESTER
W-0030, NICHEGO POLYESTER W0005S30WO and NICHEGO
POLYESTER WR961 (all manufactured by The Nippon Synthetic
Chemical Industry Co., Ltd.), and PESRESIN A-210 and PESRESIN
A-520 (all manufactured by TAKAMATSU OIL&FAT CO., LTD.).
The acid value of the polymer dispersion stabilizer is preferably in
the range of from 40 mgKOH/g to 400 mgKOH/g, and more preferably in
the range of from 60 mgKOH/g to 350 mgKOH/g. When the acid value is
less than 40 mgKOH/g, the resolvability of the alkali solution may be
degraded. And when the value is more than 400 mgKOH/g, the viscosity
of the pigment increases, and it may result in causing ejection failures
and/or degradation of the dispersion stability of the pigment.
The mass average molecular weight of the polymer dispersion
stabilizer is preferably 20,000 or less, and more preferably in the range of
from 5,000 to 20,000. When the mass average molecular weight is less
than 5,000, the dispersion stability of the dispersed pigment may be
degraded. And when it is more than 20,000, the resolvability of the
alkali solution may be degraded, and its viscosity may increase.
The content of the polymer dispersion stabilizer to 100 parts by mass
of the pigment is preferably in the range of 1 part by mass to 100 parts by
mass, and more preferably in the range of 5 parts by mass to 50 parts by

mass based on the solid content. When the content is less than 1 part by
mass, the polymer dispersion stabilizer may not sufficiently stabilize the
dispersion state. And when it is more than 100 parts by mass, the ink
viscosity increases, and it may result in causing ejection failures and/or
increase in its production cost.
- Pigment Dispersant -
The water-dispersible colorant in the third structure preferably
contains a pigment dispersant. A preferred pigment dispersant is one
selected from anion surfactants and nonionic surfactants that has an
HLB value of 10 to 20.
Examples of the anion surfactants include polyoxyethylene
alkylether acetate; alkylbenzene sulfonates such as NH4, Na and Ca;
alkyldiphenylether disulfonates such as NH4, Na and Ca; sodium
dialkylsuccinate sulfonate; sodium naphthalene sulfonate formalin
condensate; polyoxyethylene polycyclic phenylethersulfate esters such as
NH4 and Na; lauryl chlorides; polyoxyethylene alkyl ether sulfate; and
oleic acids. Among those salts, sodium dioctyl sulfosuccinate salt and
polyoxyethylene styrene phenylether sulfosuccinate ammonium salt are
particularly preferable.
Examples of the nonionic surfactants having an HLB value of 10 to
20 include polyoxyethylene alkylether, polyoxyalkylene alkylether,
polyoxyethylene polycyclic phenylether, sorbitan fatty acid ester,
polyoxyethylene sorbitan fatty acid ester, alkylphenol ethoxylate,
polyoxyethylene alkyl amine, polyoxyethylene alkylamide and acetylene

glycol. Among those, polyoxyethylene laurylether,
polyoxyethylene-p-naphthylether, polyoxyethylene sorbitan monoleate
and polyoxyethylene styrene phenylether are particularly preferable.
The content of the dispersant to 100 parts by mass of the pigment is
preferably in the range of 1 part by mass to 100 parts by mass, and more
preferably in the range of 10 parts by mass to 50 parts by mass. When
the content of the dispersant is insufficient, the pigment may not be
sufficiently miniaturized. And when the content of the dispersant is too
large, its excess component which is surplus thereof not adhering to the
pigment, may adversely affect the property of the ink, causing bleeding
and degradations in the water resistance and abrasion-resistance.
The dispersed pigment can be obtained by dissolving the pigment
dispersant in an aquatic medium, adding the pigment, sufficiently
moisturizing the mixture, and kneading/dispersing using a high-speed
agitator such as a homogenizer, a dispersion machine such as a bead mill
or ball mill, a mixing-dispersion kneader such as a roll mill using shear
force, or an ultrasonic dispersion machine. Coarse particles are likely to
exist after such kneading/dispersing process, and they often cause
blocking of inkjet nozzles and/or ink supply routes. Thus, it is necessary
that coarse particles having particle diameters of 1 µm or larger be
removed using, for example, a filter or a centrifugal separator.
The average particle diameter (D50) of the dispersed pigment in the
ink is preferably 150 nm or smaller, and more preferably 100 nm or
smaller. When the average particle diameter (D50) is larger than 150 nm,

the ejection stability may be drastically degraded, resulting in blocking of
the inkjet nozzles and/or distorting ink ejection directions. On the other
hand, when the average particle diameter (D50) is 100 nm or smaller, the
ejection stability as well as image saturation will be improved.
The content of the water-dispersible colorant in the recording ink is
preferably in the range of 2% by mass to 15% by mass and more
preferably in the range of 3% by mass to 12 % by mass based on the solid
content. When the content is less than 2 % by mass, the ink color gamut
and image densities may be drastically degraded. And when it is more
than 15 % by mass, ink viscosity increases, and it may result in the
degradation of the ink ejection stability and increase in its production
cost.
- Water-Dispersible Resin -
At least fluorine resin participates are used as the water-dispersible
resin because of their excellent film formability, or image formability, as
well as excellent water repellency, water resistance and durability, and
because they are effective means to record high density images having
excellent color gamut and water resistance.
Preferred examples of the fluorine resin particulates include those
having a fluoroolefin unit. Of such fluorine resin particulates,
particulates of vinyl ether resins composed of fluoroolefin units and vinyl
ether units are particularly preferably used.
The fluoroolefin unit is not particularly limited and can be
appropriately selected depending on the purpose. Examples thereof

include -CF2CF2-, CF2CF(CF2)- and -CF2CFCl-
The vinyl ether unit is not particularly limited and can be
appropriately selected depending on the purpose. Examples thereof
include the compounds represented by the following structural formulas.



The particulates of the vinyl ether resins composed of fluoroolefin
units and vinyl ether units are preferably alternating copolymers of the
fluoroolefin units and vinyl ether units.
For such fluorine resin particulates, either those appropriately
synthesized or commercially available products may be used. Examples
of the commercially available products include FLUONATE FEM-500 and
FEM-600, DICGUARD F-52S, F-90, F-90M and F-90N, and
AQUAFURFURAN TE5A (all manufactured by DAINIPPON INK AND
CHEMICALS, INCORPORATED); LUMIFLON FE4300, FE4500 and
FE4400, and ASAHICUARD AG-7105, AG-950, AG-7600, AG-7000 and
AG-1100 (all manufactured by ASAHI GLASS CO., LTD.).
The fluorine resin particulates may be used in combination with a
waterdispersible resin. In such case, the content of the fluorine resin
particulates in the water-dispersible resin is preferably 50 % by mass or
more, more preferably 70 % by mass or more and further preferably 80 %
by mass or more. And it is most preferred that the content substantially
be 100 % by mass.
The waterdispersible resin used in combination is not particularly
limited, and can be selected according to the purpose. Examples thereof
include condensed synthetic resins, polyaddition resins and natural
polymer compounds.
Examples of the condensed synthetic resins include polyester resins,
polyurethane resins, polyepoxy resins, polyamide resins, polyether resins

and silicon resins. Examples of the polyaddition resins include
polyolefin resins, polystyrene resins, polyvinyl alcohol resins, polyvinyl
ester resins, polyacrylic acid resins and unsaturated carboxylic acid
resins. Examples of the natural polymer compounds include celluloses,
rosins and natural rubbers.
The water dispersible resin may be used as a homopolymer or may be
copolymerized to be used as a complex resin. It can be formed into any
one of single phase structures, core shell structures and power-feed
emulsions.
Such water-dispersible resin can be selected from those themselves
have hydrophilic groups and self-dispersibility and those themselves have
no self-dispersibility while dispersibility is provided thereto by a means of
a surfactant or a resin having hydrophilic groups. Among them,
emulsions of the resin particles obtained by emulsification and/or
suspension polymerization of an ionomer of polyester resin or
polyurethane resin or an unsaturated monomer are preferable. In the
emulsification polymerization of the unsaturated monomer, it is
emulsificationpolymerized in water in which the unsaturated monomer,
a polymerization initiator, and the surfactant, a chain transfer agent, a
chelating agent and a pH adjuster are added. Thus, the water
dispersible resin can be easily obtained, and further, resin constitution
can be easily changed, enabling to obtain desired property thereof.
Examples of the unsaturated monomer include unsaturated
carboxylic acids, (meth)acrylic acid ester monomers, (meth)acrylic acid

amide monomers, aromatic vinyl monomers, vinyl cyano compound
monomers, vinyl monomers, allyl compound monomers, olefin monomers,
diene monomers, oligomers having unsaturated carbon atoms. Those
can be used alone or in combination. By using those monomers in
combination, it is possible to flexibly modify the property of the resulted
monomers. And by a means of polymerization/graft-polymerization
using an oligomer polymerization initiator, it is also possible to improve
the property of the resin.
Examples of the unsaturated carboxylic acids include acrylic acid,
methacrylic acid, itaconic acid, fumaric acid and maleic acid.
Examples of the monofunctional (meth)acrylic acid esters include
methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n butyl
methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl
methacrylate, n-hexyl methacrylate, 2ethylhexyl methacrylate, octyl
methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl
methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl
methacrylate, glycidyl methacrylate, 2:hydroxyethyl methacrylate,
2-hydroxypropyl methacrylate, dimethylaminoethyl methacrylate,
methacryloxyethyltrimethyl ammonium salts,
3-methacryloxypropyltrimethoxysilane, methyl acrylate, ethyl acrylate,
isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate,
isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate,
decyl acrylate, dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate,
phenyl acrylate, benzyl acrylate, glycidyl acrylate, 2-hydroxyethyl

acrylate, 2-hydroxypropyl acrylate, dimethylaminoethyl acrylate and
acryloxyethyltrimethyl ammonium salts.
Examples of the polyfunctional (meth)acrylic acid esters include
ethylene glycol dimethacrylate, diethylene glycol dimethacrylate,
triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate,
1,3-butylene glycol dimethacrylate, l,4butylene glycol dimethacrylate,
1.6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate,
dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate,
polybutylene glycol dimethacrylate,
2,2"-bis(4-methacryloxydiethoxyphenyl)propane, trimethylol propane
trimethacrylate, trimethylol ethane trimethacrylate, polyethylene glycol
diacrylate, triethylene glycol diacrylate, 1,3-butylene glycol diacrylate,
1,4-butylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol
diacrylate, 1,9-nonanediol diacrylate, polypropylene glycol diacrylate,
2,2"-bis(4-acryloxypropyloxyphenyl)propane,
2,2"-bis(4-acryloxydiethoxyphenyl)propane, trimethylol propane
triacrylate, trimethylol ethane triacrylate, tetramethylol propane
triacrylate, ditrimethylol tetraacrylate, tetramethylol methane
tetraacrylate, pentaerythritol tetraacrylate and dipentaerythritol
hexaacrylate.
Examples of the (meth)acrylic acid amide monomers include
acrylamides, methacrylamides, N,N-dimethylacrylamides,
methylenebisacrylamides and 2-acrylamide-2-methylpropane sulfonic
acid.

Examples of the aromatic vinyl monomers include styrenes,
a-methylstyrenes, vinyl toluenes, 4-t-butylstyrene, chlorostyrenes, vinyl
anisoles, vinyl naphthalenes and divinyl benzenes.
Examples of the vinyl cyano compound monomers include
acrylonitrile and methacrylonitrile.
Examples of the allyl compound monomers include allylsulfonic acid
and salts thereof, allylamines, allyl chlorides, diallylamines, and
diallyldimethyl ammonium salts.
Examples of the olefin monomers include ethylene and propylene.
Examples of the diene monomers include butadiene and chloroprene.
Examples of the vinyl monomers include vinyl acetates, vinylidene
chlorides, vinyl chlorides, vinyl ethers, vinyl ketones, vinyl pyrrolidones,
vinylsulfonic acids and salts thereof, vinyl trimethoxysilane and vinyl
triethoxysilane.
Examples of the oligomers having unsaturated carbon atoms include
styrene oligomers having a methacryloyl group, styreneacrylonitrile
oligomers having a methacryloyl group, methyl methacrylate oligomers
having a methacryloyl group, methyl siloxane oligomers having a
methacryloyl group and polyester oligomers having a acrylyl group.
Since breakdowns of the molecular chain, including dispersion
breaking and hydrolysis, are caused under a strong alkaline or acidic
environment, pH of the water dispersible resin is preferably in the range
of from 4 to 12, and more preferably in the range of from 6 to 11 in terms
of miscibility with the water dispersible colorant. It is further preferably

in the range of 7 to 9.
The average-particle diameter (D50) of the water dispersible resin
determines the viscosity of the dispersed liquid. Provided composition
and the solid content of the dispersed liquid remain the same, particles
having smaller diameters provide higher viscosity. The
water-dispersible resin preferably has an average particle diameter (D50)
of 50 nm or larger for preventing inks using the water-dispersible resin
from having excessively high viscosity. On the other hand, when the
water-dispersible resin has an average particle diameter of several dozen
micrometers, it cannot be used because the diameter is larger than the
diameter of inkjet nozzles. And even if the average particle diameter of
water-dispersible resin is smaller than the nozzles, excessively large
particles thereof in an ink degrade its ejection stability. Thus, for
preventing the degradation of the ejection stability, the average particle
diameter (D50) is preferably 200 nm or smaller and more preferably 150
nm or smaller.
The water-dispersible resin preferably functions as a means to fix the
water-dispersible coloring material onto paper, and preferably improves
the fixation characteristic of the colorant by filming under room
temperature. Therefore, it is preferred that a minimum film formation
temperature (MFT) of the water-dispersible resin be 30 °C or lower and
more preferably 20°C or lower.
And the glass transition temperature of the water dispersible resin is
preferably -30 °C or higher, because when the temperature is -40 °C or

lower, the viscosity of the resin film increases, resulting in the generation
of wrinkles on printed paper.
The content of the waterdispersible resin in the recording ink is
preferably in the range of from 2 % by mass to 30 % by mass and more
preferably in the range of 6 % by mass to 25 % by mass based on the solid
content.
- Wetting Agent -
The recording ink of the present invention contains water as a liquid
medium. To prevent the ink from drying, and to improve dispersion
stability, the following wetting agent is used in the ink. The wetting
agent is an effective means for preventing the degradations of the ink
ejection stability and the resolvability, caused by water evaporation.
The wetting agent is not particularly limited and can be
appropriately selected in accordance with the purpose. Examples
thereof include polyalcohols, polyalcohol alkylethers, polyalcohol aryl
ethers, nitrogen-containing heterocyclic compounds, amides, amines,
sulfur-containing compounds, propylene carbonates, ethylene carbonic
acids and other wetting agents. These may be used alone or in
combination.
Examples of the polyalcohols include glycerine, diethylene glycol,
1,3-butanediol, 3-methyM,3butanediol, triethylene glycol, propylene
glycol, dipropylene glycol, trimethylol propane, trimethylol ethane,
ethylene glycol, tripropylene glycol, tetraethylene glycol, hexylene glycol,
polyethylene glycol, polypropylene glycol, 1,5-pentadiol, 1,6-hexanediol,

glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,4-butanetriol,
1,2,3-butanetriol and petriol.
Examples of the polyvalent alcohol alkyl ether compounds include
ethylene glycol monoethyl ether, ethylene glycol monobutyl ether,
ethylene glycol monomethyl ether, diethylene glycol monoethyl ether,
diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether
and propylene glycol monoethyl ether.
Examples of the polyvalent alcohol aryl ethers include ethylene glycol
monophenyl ether and ethylene glycol monobenzyl ether.
Examples of the nitrogen-containing heterocyclic compounds include
2-pyrrolidone, Nmethyl-2-pyrrolidone, Nhydroxyethyl-2-pyrrolidone,
1,3-dimethyh'midazolidinone, e-caprolactam and γ-butyrolactone.
Examples of the amides include formamide, N-methylformamide and
N,N-dimethylformamide.
Examples of the amines include monoethanolamine, diethanolamine,
triethanolamine, monoethylamine, diethylamine and triethylamine.
Examples of the sulfur-containing compounds include
dimethylsulfoxide, sulfolane and thiodiethanol.
Preferred examples of the other wetting agents include those having
saccharides. Examples of the saccharides include monosaccharide,
disaccharide, oligosaccharide (including trisaccharide and
tetrasaccharide) and polysaccharide. Specific examples thereof include
glucose, mannose, fructose, ribose, xylose, arabinose, galactose, maltose,
cellobiose, lactose, sucrose, trehalose, and maltotriose. Herein, the term

"polysaccharide" refers to saccharides in a broad sense, and it includes
widespread natural saccharides such as acyclodextrins and celluloses
Examples of derivatives of such saccharides include reducing sugars
thereof, including sugar alcohols which are generally represented as
HOCH2(CHOH)nCH2OH (where n is an integer of 2 to 5), oxidized
saccharides such as aldonic acids and uronic acids, amino acids and thio
acids. Of those saccharides, the sugar alcohols are preferable. Specific
examples thereof include maltitol and sorbit.
Of those wetting agents, glycerol, diethylene glycol, triethylene glycol,
1,3-butanediol, 3-methyll,3butanediol, 2-pyrrolidone and
N-methyl-2-pyrrolidone are preferable because they provide excellent
storage stability and ejection stability.
The mass ratio of the pigment to the wetting agent particularly
relates to the stability of ejecting ink drops from inkjet nozzles. When
the formulation amount of the wetting agent in an ink is low relative to
the content of solidified pigment, water contained in the ink evaporates
from ink nozzles and/or ink ejecting systems, and it may result in the
blocking of the nozzles.
The content of the wetting agent in the recording ink is preferably in
the range of 20 % by mass to 35 % by mass and more preferably in the
range of 22.5 % by mass to 32.5 % by mass. By adjusting the content in
the ranges, it is possible to protect the ink from drying and improve the
storage stability of the ink, and thus the reliability of the ink can be
increased. When the content is less than 20 % by mass, the ink around

the nozzles easily dries, causing the blocking of the nozzles. When it
exceeds 35 % by mass, the drying characteristics on paper may degrade,
and image quality may also degrade on regular paper.
- Surfactants -
The surfactant can be appropriately selected from those which will
not impair the dispersion stability when used in combination with any
colorant/wetting agent and have a low surface tension and a high leveling
characteristic. It is preferably selected from one of silicone surfactants
and fluorinated surfactants. Among them, the fluorinated surfactants
are particularly preferable.
The fluorinated surfactant preferably has 2 to 16, and more
preferably 4 to 16 carbon atoms substituted with fluorine atoms. When
the number of carbon atoms substituted with fluorine atoms is less than
two, the effect of fluorine is not obtained in some cases. When it is more
than 16, problems such as degradation in the storage stability of the ink
may occur.
Examples of the fluorinated surfactants include perfluoroalkyl
sulfonic acid compounds, perfluoroalkyl carboxylic compounds,
perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide
adducts and polyoxyalkylene ether polymer compounds having
perfluoroalkyl ether group at the side chain thereof. Among them, the
polyoxyalkylene ether polymer compounds having perfluoroalkyl ether
group at the side chain are particularly preferable for its low foaming
property.

Examples of the perfluoroalkyl sulfonic acid compounds include
perfluoroalkyl sulfonic acid and perfluoroalkyl sulfonate salts.
Examples of the perfluoroalkyl carboxylic compounds include
perfluoroalkyl carboxylic acid and perfluoroalkyl carboxylate salts.
Examples of the perfluoroalkyl phosphate ester compounds include
perfluoroalkyl phosphate ester and salts of perfluoroalkyl phosphate
ester.
Examples of the polyoxyalkylene ether polymer compounds having
perfluoroalkyl ether group at side chain include polyoxyalkylene ether
polymers having perfluoroalkyl ether group at side chain, sulfates of
polyoxyalkylene ether polymers having perfluoroalkyl ether group at side
chain and salts of polyoxyalkylene ether polymers having perfluoroalkyl
ether group at side chain.
Examples of the counterions of the salts in these fluorinated
surfactants include Li, Na, K, NH4, NH3CH2CH2OH, NH2(CH2CH2OH)2
and NH(CH2CH2OH)3.
The fluorinated surfactants can be selected from either those
appropriately synthesized or commercially available products.
Examples of the commercially available products include Surflon
S-111, S-112, S-113, S-121, S-131, S-132, S-141, S-145 (manufactured by
Asahi Glass Co., Ltd.), Fullard FC-93, FC-95, FC-98, FC-129, FC-135,
FC-170C, FC-430, FC-431 (supplied from Sumitomo 3M Ltd.), Megafac
F-470, F1405, F-474 (manufactured by Dainippon Ink And Chemicals,
Incorporated), Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO,

FS-300, UR(manufactured by DuPont), FT-110, FT-250, ET-251, FT-400S,
FT-150, FT-400SW (manufactured by NEOS Company Limited) and
PF151N (manufactured by Omnova Inc.). Of those products, FS-300
(manufactured by DuPont), FT-110, FT-250, FT251, FT400S, FT-150,
FT-400SW (manufactured by NEOS Company Limited) and PF-151N
(manufactured by Omnova Inc.) are particularly preferable as they can
provide excellent image quality, and particularly they can improve color
gamut of recorded images and enable the ink to be uniformly absorbed in
paper.
Specific examples of the fluorinated surfactants include those
represented by the following structural formulas.
(1) Anionic fluorinated surfactants

Where Rf represents a mixture of fluorine containing hydrophobic
groups represented by the following structural formula. And where A
represents -SO3X, COOX or -PO3X (X is counteranion, and specifically it
may be a hydrogen atom, Li, Na, K, NH4, NH3CH2CH2OH,
NH2(CH2CH2OH)2, or NH(CH2CH2OH)3).



Where Rf represents a fluorine containing group represented by the
following structural formula. Where X represents the same as described
above. And where "n" represents an integer of 1 or 2, and "m" represents
2-n.

Where "n" represents an integer of 3 to 10.

Where Rf and X are the same as described above.

Where Rf and X are the same as described above.
(2) Nonionic fluorinated surfactants

Where Rf is the same as described above. And where "n" represents
an integer of 5 to 20.

Where Rf is the same as described above. And where "n" represents
an integer of 1 to 40.

(3) Amphoteric Fluorinated Surfactant

Where Rf is the same as described above.
(4) Oligomer-Type Fluorinated Surfactant

Where Rf" represents a fluorine-containing group represented by the
following structural formula, "n" represents an integer of 0 to 10, and X is
the same as described above.

Where "n" represents an integer of 1 to 4.

Where Rf" is the same as defined above, and "I", "m" and "n" each
represent an integer of 0 to 10.
The silicone surfactant is not particularly limited, and can be
appropriately selected in accordance with the purpose. It is preferred

that it be selected from those which are not decomposed in a high pH
environment. Examples of such surfactants include side chain modified
polydimethylsiloxane, chain ends modified polydimethylsiloxane, chain
end modified polydimethylsiloxane, and sidechain ends modified
polydimethylsiloxane. Modifying groups having a polyoxyethylene
group or a polyoxyethylene polyoxypropylene group are particularly
preferable because of their excellent characteristics as an aqueous
surfactant.
Such surfactants may be selected from those appropriately
synthesized or commercially available products.
Examples of the commercially available products include those
manufactured by BYK Japan KK, Shin-Etsu Silicones Co., Ltd., and Dow
Corning Tray Co., Ltd.
The polyether modified silicone surfactant is not particularly limited
and can be appropriately selected in accordance with the purpose.
Examples thereof include compounds obtained by introducing the
polyalkylene oxide structure represented by the following structural
formula into Si side chain of dimethyl polysiloxane.

Where "m", "n", "a" and "b" represent integers. And where R and R'

represent an alkyl group and an alkylene group respectively.
The polyether modified silicone compounds may be selected from
commercially available products. Examples thereof include KF-618,
KF-642 and KF643 (manufactured by Shin-Etsu Chemical Co., Ltd.).
The content of the surfactant in the recording ink is preferably in the
range of from 0.01 % by mass to 3.0 % by mass and more preferably in the
range of from 0.5 % by mass to 2 % by mass.
When the content is less than 0.01 % by mass, the effect of adding the
surfactant may not be obtained. When it exceeds 3.0 % by mass, the
permeability of the ink to a recording medium may excessively increase,
resulting in reduction in the image density and causing the ink to pass
through to the other side of the recording medium.
- Penetrating Agent -
It is preferred that at least a polyol compound having a solubility to
20 °C water of 0.2 % by mass to 5.0 % by mass be contained in the ink as a
penetrating agent. Examples of the polyol compound include aliphatic
diols such as 2-ethyl-2-methyl-l,3-propanediol, 3,3-dimethyl-
1,2-butanediol, 2,2-diethyll,3propanediol,
2methyl-2-propyl-l,3-propanediol, 2,4-dimethyl-2,4-pentanediol,
2,5-dimethyl-2,5hexanediol, 5hexene-l,2-diol and
2ethyl-l,3hexanediol.
Of those diols, 2ethyl-l,3hexanediol and
2,2,4trimethyM,3-pentanediol are particularly preferable.
The other penetrating agents which can be used in combination are

not particularly limited, and can be appropriately selected in accordance
with the purpose. They can be selected from those which are soluble to
the ink and can have desired properties. Examples thereof include
alkyls or arylethers of polyalcohols, including diethylene glycol
monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol
monoallyl ether, diethylene glycol monobutyl ether, propylene glycol
monobutyl ether and tetraethylene glycol chlorophenyl ether; and lower
alcohols such as ethanols.
The content of the penetrating agent in the recording ink is
preferably in the range of 0.1 % by mass to 4.0 % by mass. When the
content is less than 0.1 % by mass, the ink drying speed may be slowed,
resulting in occurrence of bleeding. And when it is more than 4.0 % by
mass, the dispersion stability of the colorant may be degraded, resulting
in frequent occurrences of nozzle blocking and excessive increase of the
permeability to a recording medium, which causes the degradation of the
image density and the ink to pass through to the other side of the
recording medium.
The other components are not particularly limited, and can be
appropriately selected in accordance with the necessity. Examples
thereof include pH adjusters, preservatives/anti-fungal agents, chelate
agents, antirusts, antioxidants, ultraviolet ray absorbers, oxygen
absorbers and photo stabilizers.
The pH adjuster is particularly limited provided it can adjust pH to a
desired level in the range of 7 to 11 without adversely affecting the

recording ink, and it can be appropriately selected in accordance with the
purpose. Examples therefor include alcohol amines, alkali metal
hydroxide, ammonium hydroxide, phosphonium hydroxide and alkali
metal carbonate salts. When the pH level is lower than 7 or higher than
11, the ink containing it excessively melts an inkjet had and ink supply
unit, and that may result in the change in ink property, causing ink
leaking and blocking ink nozzles.
Examples of the alcohol amines include diethanolamine,
triethanolamine and 2-amino-2-ethyl-l,3-propanediol.
Examples of the hydroxide of alkali metal elements includes lithium
hydroxide, sodium hydroxide and potassium hydroxide.
Examples of the hydroxide of ammonium include ammonium
hydroxide, quaternary ammonium hydroxide and quaternary
phosphonium hydroxide.
Examples of the carbonate salts of alkali metals include lithium
carbonate, sodium carbonate and potassium carbonate.
Examples of the preservatives/anti-fungal agents include sodium
dehydroacetate, sodium sorbate, sodium 2-pyridinethioMoxide, sodium
benzoate and sodium pentachlorophenol.
Examples of the chelate agents include sodium
ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium
hydroxyethyl ethylene diamine nitrilotriacetate, sodium
diethylenetriamine pentaacetic and sodium uramil diacetate.
Examples of the antirusts include acidic sulfite salts, sodium

thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrate,
pentaerythritol tetranitrate and cyclohexylammonium nitrate.
Examples of the antioxidants include phenol antioxidants (including
hindered phenol antioxidants), amine antioxidants, sulfur antioxidants
and phosphorous antioxidants.
Examples of the phenol antioxidants Gncluding hindered phenol
antioxidants) include butylated hydroxyanisole,
2,6di-tertbutyl-4-ethylphenol,
stearyl-β-(3,5-di-tert-butyl-4hydroxyphenyl)propionate,
2,2'-methylenebis(4-methyl-6-tert-butylphenol),
2,2'-methylenebis(4-ethyl-6-tert-butylphenol),
4,4'-butylidenebis(3 methyl-6-tert-butylphenol),
3,9-bis(1,1-dimethyl-2-[β-(3-tertbutyl-4-hydroxy-5-methylphenyl)propion
yloxy]ethyl]2,4,8,10-tetraixaspiro[5,5]undecane,
1,1,3-tris(2-methyl-4hydroxy-5-tert-butylphenyl)butane,
1,3,5-trimethyl-2,4,6-tris(3,5-di-tertbutyl-4-hydroxybenzyl)benzene and
tetraxis[methylene-3-(3',5'-ditert-butyl-4-hydroxyphenyl)propionate]met
hane.
Examples of the amine antioxidants include phenyl-β-naphthylamine,
a-naphthylamine, N,N'-di-sec-butyl-p-phenylenediamine, phenothiazine,
N,N'-diphenyl-p-phenylenediamine, 2,6-tert-butyl-p-cresol,
2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butyl-phenol,
butylhydroxyanisole, 2,2'-methylenebis(4-methyl-6-tert-butylphenol),
4,4'-butylidenebis(3-methyl-6-tert-butylphenol),

4,4'-thiobis(3-methyl-6-tert-butylphenol),
tetraxis[methylene-3-(3,5-di-tert-butyl-4-dihydroxyphenyl)propionate]me
thane and l,l,3-tris(3-methyl-4-hydroxy-5tert-butylphenyl)butane.
Examples of the sulfur antioxidants include dilauryl
3,3'-thiodipropionate, distearyl thiodipropionate, lauryl stearyl
thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl
β,β'-thiodipropionate, 2-mercaptobenzimidazole and dilauryl sulfite.
Examples of the phosphorous antioxidants include triphenyl
phosphite, octadecyl phosphite, triisodecyl phosphite, trilauryl
trithiophosphite, and trinonylphenyl phosphite.
Examples of the ultraviolet ray absorbers include benzophenone
based ultraviolet ray absorbers, benzotriazole based ultraviolet ray
absorbers, salicylate based ultraviolet ray absorbers, cyanoacrylate based
ultraviolet ray absorbers, and nickel complex salt based ultraviolet ray
absorbers.
Examples of the benzophenone ultraviolet ray absorbers include
2hydroxy-4-n-octoxybenzophenone,
2-hydroxy-4-n-dodecyloxybenzophenone, 2,4-dihydroxybenzophenone,
2-hydroxy-4-methoxybenzophenone, and
2,2',4,4'tetrahydroxybenzophenone.
Examples of the benzotriazole ultraviolet ray absorbers include
2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole,
2-(2'-hydroxy5'-methylphenyl)benzotriazole,
2-(2'-hydroxy-4'-octoxyphenyl)benzotriazole, and

2-(2'-hydroxy-3'-tertbutyl-5'-methylphenyl)-5-chlorobenzotriazole.
Examples of the salicylate ultraviolet ray absorbers include, for
example, phenyl salicylate, p-tert-butylphenyl salicylate, and
p-octylphenyl salicylate.
Examples of the cyanoacrylate ultraviolet ray absorbers include
ethyl-2-cyano-3,3'-diphenyl acrylate,
methyl-2-cyano-3-methyl-3(p-methoxyphenyl) acrylate, and
butyl-2-cyano-3-methyl-3-(p-methoxyphenyl) acrylate.
Examples of the nickel complex salt ultraviolet ray absorbers include
nickel bis(octylphenyl) sulfide,
2,2'-thiobis(4-tert-octylphelate)-n-butylamine nickel (II),
2,2'-thiobis(4tert-octylphelate)-2-ethylhexylamine nickel (II) and
2,2'-thiobis(4-tert-octylphelate) triethanolamine nickel (II).
The recording ink of the present invention is obtained by
dispersing/melting a waterdispersible colorant, a water-dispersible resin,
a wetting agent, a surfactant, water and other components in accordance
with necessity in a water-based medium. They may further be
stirred/mixed in accordance with necessity. Those components can be
dispersed using, for example, a sand mill, a homogenizer, a ball mill, a
paint shaker or an ultrasonic dispersing machine. The components can
be stirred/mixed using, for example, a regular stirrer equipped with
stirring wings, a magnetic stirrer or a high speed dispersing machine.
The properties of the recording ink of the present invention is not
particularly limited, and can be appropriately adjusted in accordance

with the purpose, while it is preferred that its properties including
viscosity, surface tension and pH be in the following ranges.
The viscosity of the recording ink at 25 °C is preferably in the range
of from 5 mPa.s to 20 mPa.s, and more preferably in the range of from 10
mPa.s to 20 mPa.s . When the viscosity is 5 mPa.s or more, the ink can
provide higher image density and better image quality. While excellent
ejection stability is maintained by adjusting the ink viscosity at 20 mPa.s
or lower.
The viscosity at 25 °C can be measured with, for example, RL-500 (a
viscometer manufactured by TOKI SANGYO CO., LTD.).
The surface tension of the recording ink at 25 °C is preferably 35
mN/m or lower and more preferably 30 mN/m or lower. When the
surface tension is more than 35 mN/m, the levelling of the ink on the
recording medium may be slowed, resulting in longer drying time.
The coloration of the recording ink of the present invention is not
particularly limited, can be appropriately selected in accordance with the
purpose. Examples thereof include yellow, magenta, cyan and black.
Multicolor images can be recorded using an ink set having two or more
such colors in combination. Full color images can be recorded using an
ink set having all the colors in combination.
The recording ink of the present invention can be suitably used for
printers having any types of inkjet heads. Examples of the inkjet heads
include a so-called piezoelectric type inkjet head where ink drops are
ejected by changing the volume of an ink flow path by deforming a

vibration plate which forms a wall of the ink flow path and which is
deformed using a piezoelectric element as a means to apply pressure to
the ink in the ink flow path (see JP-A No. 0251734); or a so-called
thermal inkjet head where bubbles are generated by heating the ink in
the ink flow path using an exothermic resistive element (see JP-A No.
61-59911); or an electrostatic inkjet head where the electrode and the
vibration plate which forms the wall of the ink flow path are disposed in
opposed positions, and the volume in the ink flow path is changed to eject
the ink by an electrostatic power generated between the electrode and the
vibration plate (see JP-A No. 0671882).
The recording ink of the present invention can be suitably used as an
ink for inkjet recording, as well as for variety of usages including fountain
pens, ball-points, markers and felt pens. Particularly, it can be
preferably used in inkjet image forming apparatuses such as printers that
heat a recording medium and ink to 50 °C to 200 °C before/after printing
as a means to promote fixing of a recorded image. The ink of the present
invention can particularly preferably be used for the ink/media set, ink
cartridge, ink recorded matter, inkjet recording apparatus and inkjet
recording method of the present invention.
(Ink/Media Set)
The ink/media set of the present invention contains the recording ink
and the recording medium of the present invention.

The recording medium is not particularly limited and can be

appropriately selected in accordance with the purpose. Suitable
examples thereof include regular paper, glossy coated printing paper,
special paper, fabric, film, OHP sheet and regular printing paper.
In order to obtain a recorded matter with excellent image quality, the
recording medium should have a base and a coating which is provided on
at least one side of the base, wherein the transfer amount of pure water to
the recording medium should be in the range of from 2 ml/m2 to 35 ml/m2
when measured at a contacting time of 100 ms and with a dynamic
scanning absorptometer, and the transfer amount of pure water to the
recording medium is in the range of from 3 ml/m2 to 40 ml/m2 when
measured at a contacting time of 400 ms.
The transfer amount of purified water to the recording medium at the
contacting time of 100 ms is preferably in the range of 1 mL/m2 to 5
mL/m2, and the transfer amount of purified water to the recording
medium at the contacting time of 400 ms is in the range of 3 mL/m2 to 10
mL/m2 mL/m.
When the transfer amount of the ink and purified water at the
contacting time of 100 ms is insufficient, the beading of the recording
medium may easily occur. When it is too large, the diameter of dots
forming recorded images on the recording medium may not be sufficient.
When the transfer amount at the contacting time of 400 ms is
insufficient, the recording medium cannot provide sufficiently fast drying
speed, and thus spur marks may be easily generated and. On the other
hand, when it is excessively large, the recording medium may not provide

a excellent glossy surface on a dried recorded image.
Here, the dynamic scanning absorptometer (stated in JPA's
Voluntary Action Plan and Report of Energy Situation in the Pulp and
Paper Industry in Japan vol. 48, 8892, May, 1994, Sigenori Kukan), or
DSA, is a device capable of precisely measuring the liquid absorption in
an extremely short period of time. With the dynamic scanning
absorptometer, the liquid absorption rate of the recording medium can be
automatically measured by directly measuring a liquid absorption rate
from a movement of a meniscus in a capillary, by forming a sample into a
disc form, spirally scanning a liquid absorption head, automatically
changing the scanning rate in accordance with a predetermined pattern,
and repeating the measurement procedure a desired number of times on
only one sample. A liquid supply head to a paper sample is connected to
the capillary through a Teflon (registered trade name) tube, and the
position of the meniscus in the capillary is automatically read with an
optical sensor. Specifically, using the dynamic scanning absorptometer
(K350 series D type supplied from Kyowa Seiko Co., Ltd.), the transfer
amount of purified water can be measured. The transfer amounts at the
contact time of 100 ms and 400 ms can be calculated by interpolation
based on measured values of the transfer amounts at contact time
adjacent to each contact time.
- Support -
The support is not particularly limited, can be appropriately selected
depending on the purpose, and includes, for example, paper whose major

ingredient is wood fiber and sheet-shaped substances such as nonwoven
fabrics whose major ingredients are wood fibers and synthetic fibers.
The paper is not particularly limited and can be appropriately
selected in accordance with the purpose. Examples thereof include wood
pulps and used paper pulps. Examples of the wood pulps include broad
leaved tree bleached kraft pulps (LBKP), needle leaved tree bleached
kraft pulps (NBKP), NBSP, LBSP, GP and TMP.
Raw materials of the used paper pulps include paper material used
for super white paper, white paper with rule marks, cream white paper,
card paper, super white paper, medium white paper, simili paper, color
white paper, Kent paper, white art paper, special high cut paper, other
high cut paper, and paper used for newspaper and magazines.
Standards of those types of paper are specified in Used Paper Standard
Quality Specification table issued by the Paper Recycling Promotion
Center. More specific examples of those types of paper include variety of
types of non-coated PC paper, printer sheets such as thermal paper and
pressure-sensitive paper which are generally used in IT devices; variety
of types of used OA sheets such as PPC sheets; variety of types of coated
paper including art paper, coated paper, finely coated paper and mat
paper; and variety of types of non-coated paper such as quality paper,
color high quality paper, notepaper, letter paper, packing paper, facsimile
paper, medium quality paper, newspaper, fancy-figured paper, super
ceremony paper, structure paper, pure white rolling paper, milk cartons,
chemical pulp paper and high process yield pulp-containing paper.

These may be used alone or in combination.
The used paper pulp is generally produced by a combination of the
following 4 steps-
(1) a separating step in which used paper is crumbled into fibers by a
mechanical force generated in a pulper and by a chemical reaction, and
then printed ink is separated from the fibers;
(2) a cleaning step in which contained foreign matters (plastics and
the like) and dusts are removed with a screen/cleaner;
(3) a deinking step in which the printed ink separated from the fibers
using a surfactant is removed outside by a floatation method or a washing
method; and
(4) a bleaching step in which fibers are treated with an oxidation
reaction or a reduction reaction to make the fibers whiter.
When the used paper pulp is mixed, the mixed amount of the used
paper pulp per the total amount of the pulps is preferably 40% or less for
preventing paper made of the pulps from curling after recorded.
Examples of internally added fillers used in the support include
known white pigments. Examples of the white pigments include white
inorganic pigments such as light calcium carbonates, heavy calcium
carbonates, kaolin, clays, talcs, calcium sulfates, barium sulfates,
titanium dioxides, zinc oxides, zinc sulfides, zinc carbonates, satin whites,
aluminium silicates, diatom earth, calcium silicates, magnesium silicates,
synthetic silicas, aluminas, lithopones, zeolites, magnesium carbonates
and magnesium carbonates; and organic pigments such as styrene based

plastic pigments, acrylic plastic pigments, polyethylene, microcapsules,
urea resins and melamine resins. These may be used alone or in
combination.
Examples of an internally added sizing agent used in making the
support include neutral rosin sizing agents for neutral paper making;
alkenyl succinic acid anhydrate (ASA); alkyl ketene (timers (AKD); and
petroleum resin based sizing agents. Among those, the neutral rosin
sizing agent and alkenyl succinic acid anhydrate are particularly
preferable. Although a small amount of the alkyl ketene dimer is needed
to provide sufficient size effect, it may not be preferable to added even the
small amount thereof. This is because adding the alkyl ketene dimer
decreases the friction coefficient of the surfaces of recording paper (or
medium), making the medium easier to slip on a recording medium
feeding device and feeding the medium difficult.
The thickness of the support is not particularly limited and can be
adjusted at an appropriate level in accordance with the purpose, while it
is preferably in the range of 50 µm to 300 µm. The basis weight of the
support is preferably in the range of 45 g/m2 to 290 g/m2.
- Coating Layer -
The coating layer contains a pigment and a binder, and it further
contains a surfactant and other ingredients in accordance with necessity.
As the pigment, inorganic pigments may be used alone or in
combination with organic pigments.
Examples of the inorganic pigments include kaolins, heavy calcium

carbonates, light calcium carbonates, calcium sulfites, amorphous silicas,
titanium whites, magnesium carbonates, titanium dioxides, aluminium
hydroxides, calcium hydroxides, magnesium hydroxides, zinc hydroxides
and chlorites. Among them, the kaolins are preferable for its capability
to provide excellent gloss surfaces on recorded ink images. It enables to
obtain a recorded image that is as excellent quality as an image printed
by offset printing.
Examples of the kaolins include delaminated kaolin, baked kaolin
and engineered kaolin obtained by surface modification. In order to
obtain desirable gloss surfaces, it is preferred that a kaolin having a
particle diameter distribution in which particles having a diameter of 2
mm or smaller is 80% by mass or more occupy 50% by mass or more in the
entire kaolin.
The added amount of kaolin is preferably 50 parts by mass or more
per 100 parts by mass of the binden When the added amount is less
than 50 parts by mass, excellent gloss surfaces may not be obtained. The
upper limit of the added amount is not particularly provided, while it is
more preferably 90 parts by mass or less when coating adequacies such as
fluidity and, particularly, thickening property under high shearing force
of the kaolin are taken into account.
Examples of the organic pigments include water-soluble dispersions
of, for example, styrene-acryl copolymer particles, styrene-butadiene
copolymer particles, polystyrene particles and polyethylene particles.
Two or more such organic pigments may be mixed in combination.

The added amount of the organic pigment is preferably in the range
of 2 parts by mass to 20 parts by mass relative to 100 parts by mass of all
pigments contained in the coating layer. The organic pigment which can
provide excellent gloss surfaces and its specific gravity relatively smaller
than that of the inorganic pigment enables to obtain bulky and highly
glossy coating layer having a good surface coating property. When the
added amount is less than 2 parts by mass, the above-stated effects may
not be obtained. When it exceeds 20 parts by mass, the fluidity of the
coating solution may be degraded, resulting in the reduction of
productivity of the coating layers and increase in its cost.
The organic pigment may be in a form of a compact type, a hollow
type and a doughnut type, while the hollow type preferably having an
average particle diameter (D50) of 0.2 µm to 3.0 µm and more preferably
having a void ratio of 40 % or more is preferable when the balance
between gloss surface and coating ability and flowability of the coating
liquid is taken into account.
For the binder, it is preferable to use a water-based resin.
For the water-based resin, at least one of water-soluble resins and
water dispersible resins can be suitably used. The water-soluble resins
are not particularly limited, and can be appropriately selected in
accordance with the purpose. Examples thereof include polyvinyl
alcohol, modified polyvinyl alcohols such as cation modified polyvinyl
alcohol and acetal modified polyvinyl alcohol; polyvinyl pyrrolidone and
modified polyvinyl pyrrolidone such as copolymers of polyvinyl

pyrrolidone and vinyl acetate, copolymers of vinyl pyrrolidone and
dimethylaminoethyl methacrylate, copolymers of quaternized vinyl
pyrrolidone and dimethylaminoethyl methacrylate and copolymers of
vinyl pyrrolidone and methcrylamidepropyl trimethyl ammonium
chloride; celluloses such as carboxymethylcellulose, hydroxyethylcellulose
and hydroxypropylcellulose; modified cellulose such as cationized
hydroxyethylcellulose; polyester, polyacrylic acid (ester), melamine resins
or modified products thereof; synthetic resins such as copolymers of
polyester and polyurethane; poly(meth)acrylic acid, poly(meth)acrylamide,
oxidized starch, phosphate esterified starch, self-modified starch,
cationized starch or various modified starch, polyethylene oxide, soda
polyacrylate and soda alginate. These may be used alone or in
combination.
Among them, polyvinyl alcohol, cation modified polyvinyl alcohol,
acetal modified polyvinyl alcohol, polyester, polyurethane, copolymers of
polyester and polyurethane and the like are particularly preferable for
improving the ink absorbency.
The water-dispersible resins are not particularly limited, and can be
appropriately selected in accordance with the purpose. Examples
thereof include polyvinyl acetate, copolymers of ethylene and vinyl
acetate, polystyrene, copolymers of styrene and (meth)acrylic acid,
copolymers of (meth) acry late ester, copolymers of vinyl acetate and
(meth)acrylate ester, styrene-butadiene copolymers, ethylene-propylene
copolymers and silicone-acryl based copolymers. Crosslinking agents

such as methylolized melamine, methylolized urea, methylolized
hydroxypropylene urea and isocyanate may be contained. Copolymers
having a unit such as N-methylol acrylamide and self cross-linking ability
may also be used. Two or more such water-based resins can be used in
combination.
The added amount of the water-based resin per 100 parts by mass of
the pigment is preferably in the range of 2 parts by mass to 100 parts by
mass, and more preferably in the range of 3 parts by mass to 50 parts by
mass. The added amount of the water-based resin is determined so that
the absorbency property to the recording medium of the ink is adjusted in
a desired range.
When the waterdispersible colorant is used as the colorant, a
cationic organic compound may also be used. The cationic organic
compound is not particularly limited and can be appropriately selected in
accordance with the purpose. Examples thereof include primary to
tertiary amines, monomers, oligomers and polymers of quaternary
ammonium salts which form insoluble salts by reacting with a sulfone
group, carboxyl group or amino group in a direct dye or an acidic dye
contained in a water-soluble ink. Among them, the oligomer or the
polymer is preferable.
Examples of the cationic organic compounds include dimethylamine
epichlorohydrin polycondensates, dimethylamine ammonia
epichlorohydrin condensates, poly(trimethylaminoethyl methacrylate
methyl sulfate salt), diallylamine hydrochloride salts, acrylamide

copolymers, poly(diallylamine hydrochloride salt sulfur dioxide),
polyallylamine hydrochloride salts, poly(diallylamihe hydrochloride salt
diallylamine hydrochloride salt), acrylamide diallylamine copolymers,
polyvinylamine copolymers, dicyandiamide ammonium chloride urea
formaldehyde condensates, polyalkylenepolyamine dicyandiamide
ammonium salt condensates, dimethyldiallyl ammonium chloride
polydiallylmethylamine hydrochloride salts, poly(diallyldimethyl
ammonium chloride), poly(diallyldimethyl ammonium chloride sulfur
dioxide), poly(diallyldimethyl ammonium chloride diallylamine
hydrochloride salt derivative), acrylamide diallyldimethyl ammonium
chloride copolymers, acrylate salts, acrylamide diallylamine
hydrochloride salt copolymers, ethyleneimine derivatives such as
polyethyleneimine and acrylamine polymers and modified
polyethyleneimine alkylene oxide. These may be used alone or in
combination.
Among them, it is preferable to use the low molecular weight cationic
organic compounds such as dimethylamine epichlorohydrin
polycondensate and polyallylamine hydrochloride salt in combination
with the cationic organic compound with a relatively high molecular
weight, including polyCdiallyldimethyl ammonium chloride). By using
those in combination, the image density is enhanced, and also it is
possible to reduce the occurrence of feathering compared with using only
one of them.
The cation equivalent of the cationic organic compound, measured by

a colloid titration technique using polyvinyl potassium sulfate and
toluidine blue, is preferably in the range of 3 meq/g to 8 meq/g. When
the cation equivalent is in that range, excellent ink properties can be
obtained in the range of the dried adhesion amount mentioned below.
When the cation equivalent is measured by the colloid titration
technique, the cationic organic compound is diluted with distilled water
so that the solid content is 0.1% by mass, while pH is not adjusted.
The dried adhesion amount of the cationic organic compound is
preferably in the range of 0.3 g/m2 to 2.0 g/m2. When the dried adhesion
amount of the cationic organic compound is less than 0.3 g/m2, the image
density may not be sufficiently improved and the occurrence of feathering
may not be prevented.
The surfactant is not particularly limited and can be appropriately
selected in accordance with the purpose. It can be selected from any one
of anionic surfactants, cationic surfactants, ampholytic surfactants and
nonionic surfactants. Among those, the nonionic surfactants are
particularly preferable. By adding the surfactant, the water resistance
of the image can be enhanced, the image density can be improved and
occurrence of bleeding can be prevented.
Examples of the nonionic surfactants include higher alcohol ethylene
oxide adducts, alkylphenol ethylene oxide adducts, fatty acid ethylene
oxide adducts, polyvalent alcohol fatty acid ester ethylene oxide adducts,
higher aliphatic amine ethylene oxide adducts, fatty acid amide ethylene
oxide adducts, ethylene oxide adducts of fats and oils, polypropylene

glycol ethylene oxide adducts, fatty acid ester of glycerol, fatty acid ester
of pentaerythritol, fatty acid ester of sorbitol and sbrbitan, fatty acid ester
of sucrose, alkyl ether of polyvalent alcohol and fatty acid amide of
alkanolamine. These may be used alone or in combination.
The polyvalent alcohols are not particularly limited and can be
appropriately selected in accordance with the purpose. Examples
thereof include glycerols, trimethylolpropanes, pentaerythrits, sorbitols
and sucroses.. An ethylene oxide adduct, those in which a part thereof is
substituted with alkylene oxide such as propylene oxide or butylene oxide
in the range in which water solubility can be kept are available. The
replacement rate is preferably 50 % or less. HLB (ratio of the
hydrophilicity to the hydrophobicity) of the nonionic surfactant is
preferably in the range of from 4 to 15 and more preferably in the range of
from 7 to 13.
The added amount of the surfactant per 100 parts by mass of the
cationic organic compound is preferably in the range of 0 part by mass to
10 parts by mass and more preferably in the range of 0.1 parts by mass to
1.0 part by mass.
Other necessary ingredients may be added to the coating layer,
provided that the ingredients are within the scope of the present
invention and can achieve desired effects. Examples of the other
components include additives such as alumina powders, pH adjusters,
preservatives and antioxidants.
The method of forming the coating layer is not particularly limited,

and can be appropriately selected in accordance with the purpose. For
example, it can be formed by impregnating the support with a coating
solution or applying the coating solution on the support. The method of
the impregnation/application is not particularly limited and can be
appropriately selected in accordance with the purpose. For example, a
coating machine therefor can be selected from various coating machines
including a conventional size press, a gate roll size press, a film transfer
size press, a blade coater, a rod coater, an air knife coater and a curtain
coater. However, in terms of cost, the coating solution should be
impregnated or deposited using the conventional size press, the gate roll
size press or the film transfer size press installed in a paper making
machine, and finished with an on-machine.
The amount of the coating solution to be provided on the support is
not particularly limited and can be adjusted at an appropriate level in
accordance with the purpose, while it is preferably in the range of 0.5 g/m2
to 20 g/m2 and more preferably in the range of 1 g/m2 to 15 g/m2 based on
the solid content.
Subsequently, the thus formed coating layer may be dried in
accordance with necessity. In this case, drying temperature is not
particularly limited and can be an appropriate level in accordance with
the purpose, while it is preferably in the range of about 100°C to 250°C.
The recording medium may contain a back layer on a backside of the
support and another layer in between the support and the coating layer or
in between the support and the back layer. And a protection layer may

also be formed on the coating layer. A monolayer or multilayer may be
formed.
The recording medium can be selected from variety of inkjet
recording paper as well as from other commercially available products
including regular printing paper, coated paper for offset printing and
coated paper for gravure printing.
Commercially available coated paper for printing include those used
for industrial printing and publications, including cast-coated paper, art
paper of A0 and A1 sizes, A2 size coated paper, A3 size coated paper, B2
size coated paper, light weight coated paper and lightly coated paper.
Those types of paper are used for offset printing, gravure printing or the
like.
More specifically, examples thereof include AURORACOATER
(available from Nippon Paper Group, Inc.) and POD GLOSSCOAT
(available from Oji paper Co., Ltd.).
(Ink cartridge)
The ink cartridge of the present invention contains a container for
housing the recording ink of the present invention, and further contains
appropriately selected other members in accordance with the necessity.
The container is not particularly limited, and its shape, structure,
size and material can be appropriately determined in accordance with the
purpose. Suitable examples thereof include ink containers at least
having an ink bag made of, for example, aluminum laminate film or resin
film.

Subsequently, the ink cartridge will be described with reference to
FIGs. 1 and 2. FIG. 1 is a view exemplarily showing the ink cartridge of
the present invention. FIG. 2 is a view exemplarily showing a case (or
an external container) housing the ink cartridge 200 of FIG. 1.
As shown in FIG. 1, ink is filled in the ink cartridge 200 from an ink
inlet 242 into an ink bag 241, air/gas existing therein is deaerated, and
then the ink inlet 242 is thermally fused to be closed. When used, the
ink cartridge 200 supplies ink to an inkjet recording apparatus through a
needle coming through an ink outlet 243 which is a rubber member.
The ink bag 241 is a packing member made of, for example,
aluminium laminate film having no air permeability. As shown in FIG. 2,
the ink bag 241 is usually housed in a plastic cartridge case 244 and
detachably loaded in various inkjet recording apparatuses to be used.
The ink cartridge of the present invention contains the recording
ink/ink set of the present invention and detachably loaded in various
inkjet recording apparatus to be used. It is particularly preferred that
the ink cartridge of the present invention be detachably loaded in the
inkjet recording apparatus of the present invention, described below.
(Inkjet Recording Apparatus and Inkjet Recording Method)
The inkjet recording apparatus of the present invention contains at
least an ink ejecting unit, and it further contains appropriately selected
other units such as an impulse generating unit and a control unit in
accordance with the necessity.
The inkjet recording method of the present invention contains at

least an ink ejecting step, and it further contains appropriately selected
other steps such as an impulse generating step and a controlling step in
accordance with the necessity.
The inkjet recording method of the present invention can be suitably
performed with the inkjet recording apparatus of the present invention.
The ink ejecting step can be suitably performed with the ink ejecting unit.
And the forementioned other steps can be suitably performed with the
forementioned other units accordingly.
- Ink Flying Step and Ink Flying Unit -
The ink ejecting step is for ejecting drops of the recording ink of the
present invention by applying impulse thereto to thereby form an image.
The ink ejecting unit is for ejecting drops of the recording ink of the
present invention by applying impulse thereto to thereby form an image.
The ink ejection unit is not particularly limited. Examples thereof
include variety of nozzles for ejecting ink drops.
The impulse can be generated with, for example, the impulse
generating unit. The impulse is not particularly limited and can be
appropriately selected in accordance with the purpose. Examples
thereof include heat, pressure, vibration, and light. Those may be used
alone or in combination. Among those, heat and pressure are suitable.
Examples of the impulse generating unit include heaters, pressure
devices, piezoelectric devices, vibration generators, ultrasonic oscillators
and lights. More specific examples include piezoelectric actuators
including piezoelectric devices, thermal actuators utilizing the phase

change by generating liquid film boiling with an electric-heat converter
such as a heat element, shape memory alloy actuators utilizing the metal
phase change generated by temperature variation, and electrostatic
actuators utilizing an electrostatic force.
The method of ejecting the ink drops of the recording ink is not
particularly limited and can be selected in accordance with a selected
impulse to be applied. For example, when heat is used as the impulse,
heat energy generated correspondingly to recording signals is imparted
through, for example, a thermal head to the recording ink housed in a
recording head to thereby generate bubbles in the recording ink, and then
the recording ink is ejected in the form of drops from nozzles at the
recording head by the pressure of the bubbles. When pressure is used as
the impulse, the ink drops can be ejected by, for example, applying a
voltage to the piezoelectric element provided to a so-called pressure room
located in the ink flow path of the recording head so that the piezoelectric
element is bended and thus the volume of the pressure room is reduced,
ejecting the recording ink in the form of drops from the nozzles.
The amount of the ink drops is preferably in the range of from 3 pl to
40 pl. The ejection speed of the ink drops is preferably in the range of
from 5 m/s to 20 m/s. The frequency of the impulse applied to the ink is
preferably 1 kHz or higher. It is preferred that formed images have a
resolution of 300 dpi or higher.
The control unit is not particularly limited and can be appropriately
selected in accordance with the purpose, provided that it is suitable for

controlling the movements of the above-stated units. Examples thereof
include variety of instruments such as sequencers and computers.
An embodiment of carrying out the inkjet recording method of the
present invention using the inkjet recording apparatus of the present
invention will be described with reference to the drawings. As shown in
FIG. 3, the inkjet recording apparatus contains a body 101, a paper
feeding tray 102 for loading paper attached to the body 101, a copy
receiving tray 103, attached to the body 101, for stocking the paper on
which images are recorded (formed), and an ink cartridge loading section
104. In FIG. 3, 111 is an upper cover, and 112 indicates the front side of
the inkjet recording apparatus.
An operation section 105 including operation keys and/or displays is
provided on the ink cartridge loading section 104. The ink cartridge
loading section 104 has an openable and closable front cover 115 provided
for enabling to exchange an ink cartridge 201.
As shown in FIGs. 4 and 5, a carriage 133 is retained with a guide rod
131 and a stay 132 in the main body 101 so that the carriage 133 can
slidably retained in the primary scanning direction. The guide rod 131
is beard with two side plates (not shown) provided right and left of the
guide rod 131. The carriage 133 is driven with a main scanning motor
(not shown) in the direction indicated by the arrow shown in FIG. 5.
In the carriage 133, recording heads 134 which are composed of four
heads for ejecting recording inks of yellow (Y), cyan (C), magenta (M) and
black (B) are arranged in the direction intersecting with the primary

scanning direction. The ink drop ejecting direction of the recording
heads 134 is directed downward.
Examples of such inkjet heads which constitute the recording heads
134 include those equipped with a energy generating means to eject ink
drops, including piezoelectric actuators such as piezoelectric elements,
thermal actuators utilizing the phase change by generating liquid film
boiling with an electric-heat converter such as a heat element, shape
memory alloy actuators utilizing the metal phase change generated by
temperature variation, and electrostatic actuators utilizing an
electrostatic force.
The carriage 133 contains sub-tanks 135 for each color ink for
supplying them to the recording head 134. Each color of the recording
ink of the present invention is supplied from the ink cartridge 201 of the
present invention, provided in the ink cartridge loading section 105, to
the sub-tanks 135 through ink supplying tubes (not shown).
As a means to supply paper 142 loaded on a paper loading section (or
a pressuring plate) 141 which is located at the copy receiving tray 103,
emilunar rollers (or paper supply rollers 143) and a separation pad 144
are provided. The paper supply rollers 143 are to separate and feed a
sheet of paper one-by-one from loaded paper 142. The separation pad
144 is facing the paper supply rollers 143 and composed of a material
having a large friction coefficient. The separation pad 144 is biased
toward the paper supply rollers 143.
Paper 142 supplied by the means to supply paper is fed under the

recording head 134 with the following means; a feeing belt 151 for feeding
paper 142 by electrostatic absorption; a counter roller 152 for feeding
paper 142 from the means through a guide 145 by sandwiching paper
with the feeding belt 151; a feeding guide 153 for rotating fed paper 90° so
that its longitudinal direction is changed from substantially
perpendicularly to parallel to the direction of feeding belt 151; and a
tip-pressurizing roller 155 which is a part of pressuring section 154 and
provided on the feeding belt 151. The feeding belt 151 is provided with a
charge roller 156 as a charging unit for charging the surface of the belt.
The feeding belt 151 is an endless belt, provided and tensioned
between a feeding roller 157 and a tension roller 158, and capable of to be
rotated in the paper feeding direction. The feeding belt 151 contains, for
example, a resin surface layer which serves as a surface for transporting
paper, has a thickness of around 40 µm and an uncontrolled resistance
and is made of, for example, a copolymer of tetrafluoroethylene and
ethylene, or ETFE, and a back layer (such as middle resistance layer or
grounding layer) which is made of the same material as the resin surface
layer and has a resistance controlled with carbon. A guide member 161
corresponding to the printing region of the recording head 134 is provided
on the back layer of the feeding belt 151. A separation claw 171, paper
discharging rollers 172 and a paper discharging roller 173 are provided as
means to discharge paper 142 on which an image has been recorded with
the recording head 134. The separation claw 171 serves as a means to
separate paper 142 from the feeding belt 151. And a copy receiving tray

103 for discharged paper is provided under the paper discharging roller
172.
A both-sides paper feeding unit 181 is detachably attached to the
backside of the body 101. The both-sides paper feeding unit 181 takes
paper 142 which is returned from the feeding belt 151 by reversely
rotating the belt, reverses that taken paper, and then feed the reversed
paper in between the counter roller 152 and the feeding belt 151. A
manual paper feeding section 182 is provided at the upper area of the
both-sides paper feeding unit 181.
In this inkjet recording apparatus, paper 142 is separated and fed
one-by-one with the means to supply paper with its longitudinal direction
directed to the substantially perpendicularly to the feeding direction,
guided with the guide 145, and fed by sandwiched in between the feeding
belt 151 and the counter roller 152. The edge of that paper is further
guided with the feeding guide 153 to be mounted on the feeding belt 151
by pressurizing it with the tip-pressurizing roller 155, and then its
longitudinal direction is rotated about 90° against the feeding direction.
At that time, the feeding belt 157 is charged by the charge roller 156,
and paper 142 is electrostatically attached to the feeding belt 151 to be
transported. The recording head 134 is driven in accordance with image
signals while the carriage 133 moves, ejects ink drops onto paper 142,
when whose moving is stopped to be provided with the ink drops, to
record one line of letters, characters or images, and then paper 142 is fed
by a predetermined distance to be ready for recording the next line. A

recording operation is terminated when the inkjet recoding apparatus
receives either a recording termination signal or a signal indicating that
the bottom edge of paper 142 is reached in the recording region. Then,
paper 142 is discharged to the copy receiving tray 103.
When that the remaining amount of the recording ink in the sub-tank
135 reaches close to empty is detected, a given amount of the recording
ink is supplied from the ink cartridge 201 to the sub-tank 135.
When the recording ink contained in the ink cartridge 201 of the
inkjet recording apparatus is finished, only the ink bag in the ink
cartridge 201 needs replacing. The ink bag can be taken out therefrom
by opening the ink cartridge 201. The ink cartridge 201 can maintain its
capability of stably supplying recording ink when it is vertically placed at
the front area of the of the body 101. In that case, the ink cartridge 201
can be easily replaced even when the space above the body 101 is not
opened in its surrounding circumstance - such as when it is placed in a
shelf or when something is on the body 101.
Here, the example in which the recording ink of the present invention
is applied to a serial type (shuttle type) inkjet recording apparatus in
which the carriage scans is described, while the recording ink can
likewise be applied to line type inkjet recording apparatuses having a line
type head.
The inkjet recording apparatus and the inkjet recording method of
the present invention can be applied to various recordings using an inkjet
recording system. Particularly suitable examples to which they can be

suitably applied include printers for inkjet recording, facsimile
apparatuses, photocopiers and printer/facsimile/photocopy complex
machines.
( ink Recorded Matter)
The ink recorded matter of the present invention is recorded by the
means of the inkjet recording apparatus and the inkjet recording method
of the present invention.
The ink recorded matter of the present invention is composed of a
recording medium and an image formed on the recording medium using
the recording ink of the present invention.
The ink recorded matter of the present invention is composed of a
recording medium of the ink/media set of the present invention and an
image formed on the recording medium using the recording ink of the
ink/media set of the present invention.
The recording medium is not particularly limited and can be
appropriately selected in accordance with the purpose. Examples
thereof include regular paper, gloss paper, special paper, regular printing
paper, fabrics, films and OHP sheets. These may be used alone or in
combination.
The ink record matter can provide high image quality without
bleeding and excellent over-time stability, and thus it can be suitably
used for various usages including source materials on which various
letters/characters and/or images are recorded.

EXAMPLES
Hereinafter, with referring to Examples and Comparative Examples,
the invention is explained in detail and the following Examples and
Comparative Examples should not be construed as limiting the scope of
this invention.
(Preparation Example l)
- Preparation of Aqueous Solution A of Water-Soluble Polymer
Compound -
10.0 parts by mass of alpha-olefin/maleic anhydride copolymer
(T-YP112, manufactured by SEIKO PMC Corporation) represented by the
following structural formula 1, which has an olefin chain with 20 to 24
carbon atoms, an acid value of 190 mgKOH/g and a weight-average
molecular weight of 10,000

17.34 parts by mass of normal LiOH aqueous solution having an acid
value 1.2 times higher than alphaolefin/maleic anhydride copolymer of
the structural formula 1
72.66 parts by mass of ion-exchanged water
To prepare aqueous solution A of a water-soluble polymer compound,
the above-stated components were heated and mixed using a mixer,
alphaolefin/maleic anhydride copolymer represented by the structural

formula 1 was dissolved into the thus obtained mixture, and then a very
small amount of undissolved articles existed in the solution was removed
by filtering using a filter having an average pore diameter of 5 urn.
(Preparation Example 2)
- Preparation of Dispersed Solution of Surface-Treated Black Pigment
Into 3,000 ml of 2.5 N sodium sulphate solution, 90g of carbon black
having a CTAB specific surface area of 150 m2/g and a DBP oil absorption
amount of 100 mL/100 g was added. The thus obtained solution was
stirred at 300 rpm under 60 °C, and reacted for 10 hours. Thus, it was
subjected to an oxidation treatment. The thus obtained reaction solution
was filtrated to obtain filtrated carbon black. The obtained carbon black
was neutralized with sodium hydroxide solution and subjected to an
ultra-filtration.
The resulted carbon black was washed and dried, and then it was
dispersed in purified water. The solid content thereof in the thus
obtained solution was adjusted to 30 % by mass, and it was sufficiently
stirred. Thereby a dispersed solution of black pigment was obtained.
The average particle diamter (D50) of the dispersed pigment was
measured, revealing it was 103 nm. To measure the average particle
diamter (D50), NANOTRAC UPAEX150 (a particle size analyzer
manufactured by NIKKISO Co., Ltd.) was used.
(Preparation Example 3)
- Preparation of Magenta Pigment-Containing Polymer Particulates

Dispersed in Water -

Into a 1 L flask which was equipped with a mechanical stirrer, a
thermometer, a nitrogen gas introducing tube, a reflux tube and a drop
funnel and was sufficiently charged with nitrogen gas, 11.2 g of styrene,
2.8 g of acrylic acid, 12.0 g of lauryl methacrylate, 4.0 g of polyethylene
glycol methacrylate, 4.0 g of styrene macromer and 0.4 g of
mercaptoethanol were placed. Then, they were mixed in the flask and
heated to 65 °C. Subsequently, a mixed solution of 100.8 g of styrene,
25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of
polyethylene glycol methacrylate, 60.0 g of hydroxyethyl methacrylate,
36.0 g of styrene macromer, 3.6 g of mercaptoethanol, 2.4 g of
azobismethyl valeronitrile and 18 g of methyl ethyl ketone was added
dropwise into the flask over 2.5 hours. After dripping, another mixed
solution of 0.8 g of azobismethyl valeronitrile and 18 g of methyl ethyl
ketone was added dropwise into the flask over 0.5 hours. After maturing
at 65°C for 1 hour, 0.8 g of azobismethyl valeronitrile was added, and then
the mixture was further matured for 1 hour. Then, 364 g of methyl ethyl
ketone was added into the flask to prepare 800 g of polymer solution A
having a concentration of 50 % by mass.
in Water>
The following ingredients were sufficiently mixed- 28 g of polymer
solution A, 42 g of C.I. pigment red 122, 13.6 g of 1 mol/L potassium

hydroxide aqueous solution, 20 g of methyl ethyl ketone and 13.6 g of
ion-exchanged water. Then, the thus obtained mixture was kneaded
using a roll mill. The thus obtained paste was placed into 200 g of
purified water, and the resulted mixture was sufficiently mixed. Then,
methyl ethyl ketone and water were removed therefrom using an
evaporator. In order to remove coarse particles from the resulted
dispersed solution, it was subjected to a pressure filtration using a
polyvinylidene-fluoride membrane filter which had an average pore
diameter of 5.0 µm. Thus obtained magenta polymer particulates
dispersed in water had 15 % by mass of the pigment and 20 % by mass of
the solid content. The average particle diameter (D50) of the thus
obtained dispersed pigment was measured, revealing it was 145 nm. To
measure the average particle diameter (D50), NANOTRAC UPA-EX150 (a
particle size analyzer manufactured by NIKKISO Co., Ltd.) was used.
(Preparation Example 4)
- Preparation of Dispersed Solution of Yellow Pigment Surfactant -
30.0 parts by mass of a monosazo yellow pigment (C. I. pigment
yellow 74 manufactured by Dainichiseika Color & Chemicals Mfg. Co.,
Ltd.)
10.0 parts by mass of polyoxyethylene styrene phenylether (NOIGEN
EA-177, a nonionic surfactant manufactured by Dai-ichi Kogyo Seiyaku
Co., Ltd., having an HLB value of 15.7)
60.0 parts by mass of ion-exchanged water
The surfactant was dissolved into that ion-exchanged water. Then,

the pigment was mixed into the mixture. The ingredients of the resulted
mixture which had sufficient moisture were dispersed at 2,000 rpm for 2
hours using a wet dispersion machine (DYNOMILL KDLA,
manufactured by WAB Co., Ltd.) equipped with zirconia beads 0.5 mm in
diameter. Thereby a primary dispersed pigment was obtained.
Subsequently, 4.26 parts by mass of TAKELAC W5661 (a water- soluble
polyurethane resin manufactured by MITSUI TAKEDA CHEMICALS,
INC., having 35.2 % by mass of an active component, an acid value of 40
mgKOH/g and weight average molecular weight of 18,000) was added as
an aqueous solution of water-soluble polymer compound to the primary
dispersed pigment. The thus obtained mixture was sufficiently mixed,
and thereby a dispersed solution of yellow pigment surfactant was
obtained. The average particle diameter (D50) of the thus obtained
dispersed pigment was measured, revealing it was 62 nm. To measure
the average particle diameter (D50),.NANOTRAC UPA-EX150 (a particle
size analyzer manufactured by NIKKISO Co., Ltd.) was used.
(Preparation Example 5)
- Preparation of Dispersed Solution of Magenta Pigment Surfactant -
30.0 parts by mass of a quinacridone pigment (C. I. pigment red 122
manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.)
10.0 parts by mass of polyoxyethylene-p-naphthylether (RT-100, a
nonionic surfactant manufactured by Takemoto Yushi Co., Ltd., having an
HLB value of 18.5)
60.0 parts by mass of ion-exchanged water

The surfactant was dissolved into that ion-exchanged water. Then,
the pigment was mixed into the mixture. The ingredients of the resulted
mixture which had sufficient moisture were dispersed at 2,000 rpm for 2
hours using a wet dispersion machine (DYNOMILL KDLA,
manufactured by WAB Co., Ltd.) equipped with zirconia beads 0.5 mm in
diameter. Thereby a primary dispersed pigment was obtained.
Subsequently, 7.14 parts by mass of JC-05 (a water-soluble
styrene-(meth)acrylic copolymer manufactured by SEIKO PMC
Corporation, having 21 % by mass of an active component, an acid value
of 170 mgKOH/g and a weight average molecular weight of 16,000) was
added into the primary dispersed pigment. They were sufficiently mixed,
and thereby a dispersed solution of magenta pigment surfactant was
obtained. The average particle diameter (D50) of the thus obtained
dispersed pigment was measured, revealing it was 83 nm. To measure
the average particle diameter (D50), NANOTRAC UPAEX150 (a particle
size analyzer manufactured by NIKKISO Co., Ltd.) was used.
(Preparation Example 6)
- Preparation of Dispersed Solution A of Cyan Pigment Surfactant -
30.0 parts by mass of phthalocyanine pigment (C. I. pigment blue
15:3 manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.)
10.0 parts by mass of polyoxyethylene laurylether (DKSNL-450, a
nonionic surfactant manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.,
having an HLB value of 18.3)
60.0 parts by mass of ion-exchanged water

The surfactant was dissolved into that ion-exchanged water. Then,
the pigment was mixed into the mixture. The ingredients of the resulted
mixture which had sufficient moisture were dispersed at 2,000 rpm for 2
hours using a wet dispersion machine (DYNOMILL KDLA,
manufactured by WAB Co., Ltd.) equipped with zirconia beads 0.5 mm in
diameter. Thereby a primary dispersed pigment was obtained.
Subsequently, 7.51 parts by mass of the aqueous solution A of
water-soluble polymer compound of Preparation Example 1 and 2.51
parts by mass of NICHEGO POLYESTER W0030 (a water-soluble
polyester resin manufactured by Nippon Synthetic Chemical Industry Co.,
Ltd., having 29.9 % by mass of an active component, an acid value of 100
mgKOH/g and a weight average molecular weight of 7,000) were added
into the primary dispersed pigment. The resulted mixture was
sufficiently mixed, and thereby dispersed solution A of cyan pigment
surfactant was obtained. The average particle diameter (D50) of the
dispersed pigment was measured, revealing it was 78 nm. To measure
the average particle diameter (D50), NANOTRAC UPA-EX150 (a particle
size analyzer manufactured by NIKKISO Co., Ltd.) was used.
(Preparation Example 7)
- Preparation of Dispersed Solution B of Cyan Pigment Surfactant -
30.0 parts by mass of phthalocyanine pigment (C. I. pigment blue
15:3 manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.)
10.0 parts by mass of polyoxyethylene styrene phenylether (NOIGEN
EA-177, a nonionic surfactant manufactured by Daiichi Kogyo Seiyaku

Co., Ltd., having an HLB value of 15.7)
60.0 parts by mass of ion-exchanged water
The surfactant was dissolved into that ion-exchanged water. Then,
the pigment was mixed into the mixture. The ingredients of the resulted
mixture which had sufficient moisture were dispersed at 2,000 rpm for 2
hours using a wet dispersion machine (DYNO-MILL KDLA,
manufactured by WAB Co., Ltd.) equipped with zirconia beads 0.5 mm in
diamter. Thereby a primary dispersed pigment was obtained.
Subsequently, 15.0 parts by mass of the aqueous solution A of
water-soluble polymer compound of Preparation Example 1 was added in
the primary dispersed pigment. They were sufficiently mixed, and
thereby dispersed solution B of cyan pigment surfactant was obtained.
The average particle diameter (D50) of the thus obtained dispersed
pigment was measured, revealing it was 80 nm. To measure the average
particle diameter (D50), NANOTRAC UPAEX150 (a particle size analyzer
manufactured by NIKKISO Co., Ltd.) was used.
(Preparation Example 8)
- Preparation of Dispersed Solution C of Cyan Pigment Surfactant -
30.0 parts by mass of phthalocyanine pigment (C. I. pigment blue
15:3 manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.)
10.0 parts by mass of polyoxyethylene laurylether (DKSNL-450, a
nonionic surfactant manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.,
having an HLB value of 18.3)
60.0 parts by mass of ion-exchanged water

The surfactant was dissolved into that ion-exchanged water. Then,
the pigment was mixed into the mixture. The ingredients of the resulted
mixture which had sufficient moisture were dispersed at 2,000 rpm for 2
hours using the wet dispersion machine (DYNO-MILL KDLA,
manufactured by WAB Co., Ltd.) equipped with the zirconia beads 0.5 mm
in diamter. Thereby a dispersed solution C of cyan pigment surfactant
was obtained. The average particle diameter (D50) of the thus obtained
dispersed pigment was measured, revealing it was 75 nm. To measure
the average particle diameter (D50), NANOTRAC UPA-EX150 (a particle
size analyzer manufactured by NIKKISO Co., Ltd.) was used.
(Examples 1 to 12 and Comparative Examples 1 to 7)
- Preparation of Recording Ink -
Recording inks were obtained as follows. The ingredients for each
Example/Comparative Example, the wetting agent, penetrating agent,
surfactant, fungicide and water, shown in the following Tables 1 to 4 were
uniformly mixed for 1 hour. Waterdispersible resins were added to each
of the thus obtained mixed solutions, and the each mixture was mixed for
1 hour. Furthermore, pigment dispersed solutions and deforming agents
were added thereto and mixed for 1 hour. In order to remove coarse
particles and foreign matters from the resulted dispersed solution, it was
subjected to a pressure filtration using a polyvinylidenefluoride
membrane filter which had an average pore diameter of 5.0 nm. Thereby
recording inks of Examples 1 to 12 and Comparative Examples 1 to 7
were obtained.









Omitted explanations will be provided for compounds found in Tables
1 to 4 as follows.
Fluorine resin emulsion A- LUMIFLON FE 4300 manufactured by
ASAHI GLASS CO., LTD., which had a solid content of 50 % by mass, an
average particle diameter of 150 nm and a minimum film formation
temperature (MFT) of 30 °C or lower
Fluorine resin emulsion B: LUMIFLON FE 4500 manufactured by
ASAHI GLASS CO., LTD., which had a solid content of 50 % by mass, an
average particle diameter of 160 nm and a minimum film formation
temperature (MFT) of 28 °C or lower.
Fluorine resin emulsion C: LUMIFLON FE 4400 manufactured by
ASAHI GLASS CO., LTD., which had a solid content of 50 % by mass, an
average particle diameter of 200 nm or smaller and a minimum film
formation temperature (MFT) of 55 °C
Polyurethane emulsion: HYDRAN APX-101H manufactured by
Dainippon Ink and Chemicals, Incorporated, which had a solid content of
45 % by mass, an average particle diameter of 160 nm and a minimum
film formation temperature (MFT) of 20 °C or lower
POLYFOX PF-151N: a 50 % solution of non-ionic fluorinated oligomer
surfactants manufactured by OMNOVA Solutions Inc.
ZONYL FS-300: a 40 % solution of polyoxyethylene perfluoro
alkylether manufactured by DuPont Ltd.
KF-643: a 100 % solution of polyether modified silicone surfactant
manufactured by Shin-Etsu Chemical Co., Ltd.

SOFTANOL FP-5035: a 100 % solution of polyoxyethylene
polyoxypropylene branched alkylether manufactured by Nippon Shokubai
Co. Ltd.
Proxel GXL- a 20 % dipropylene glycol-containing solution of 1, 2
-benzisothiazolin-3-one and a fungicide manufactured by Avecia Ltd.
KM-72F: a 100 % solution of self-emulsifying silicone deforming
agent manufactured by Shin-Etsu Silicones
The recording inks of Examples 1 to 12 and Comparative Examples 1
to 7 were evaluated as described below. The results are shown, in Tables
5 and 6.

The ratio of the solid content of the resin in the water-soluble resin
(emulsion) to the solid content of the pigment, or the solid content (A) of
the resin / the solid content (B) of the pigment, was measured for each of
the recording inks.

The total content of the pigment and resin, or emulsion and
water-soluble resin, in each of the recording inks was measured.

The ink viscosities at 25 °C were measured with RL500 (a
viscometer manufactured by TOKI SANGYO CO., LTD.).

The ink surface tensions at 25 °C were measured using CBVP-Z (a
full automatic tensiometer manufactured by Kyowa Interface Science Co.,

Ltd.).
- Evaluation of Image Recording Quality -
IPSIOG707 (an inkjet printer manufactured by Ricoh Company, Ltd.)
was used under 23 °C and 50 % relative humidity to record an image on a
recording medium. The driving voltage applied to the piezoelectric
elements was adjusted so that the ejected ink drops forming image were
in a uniform amount.

An A4 size chart-document having fill areas each occupying 5 % of
the total area per color, obtained using Microsoft Word 2000, was printed
on 200 sheets of paper using Type 6200 (a printer manufactured by NBS
Ricoh Co., Ltd.). After the completion of printing, nozzles for each color
of the printer were investigated to evaluate the ejection stability. The
printer was run using the driver software supplied with the printer.
Before the printing, the printing mode was changed from "regular paper -
normal / fast" to "no color correction" in the user configuration menu for
regular paper.

A: No ejection disturbance was recognized.
B: Slight ejection disturbance was recognized.
C: Ejection disturbance or ejection blocking was recognized.

A chart-document having 64 point block (■) portions, obtained using
Microsoft Word 2000, was printed on a sheet of paper using Xerox 4024 (a

printer manufactured by Fuji Xerox Co., Ltd.). After the completion of
printing, the color of the printed block portions was investigated with
X-Rite 938 to evaluate the image density using the following evaluation
criteria. The printer was run using the driver software supplied with
the printer. Before the printing, the printing mode was changed from
"regular paper - normal / fast" to "no color correction" in the user
configuration menu for regular paper.

A: Black: 1.3 or more - Yellow: 0.85 or more - Magenta: 0.95 or more -
Cyan-1.1 or more
B: Black: 1.2 or more to less than 1.3 - Yellow: 0.8 or more to less than
0.85 - Magenta: 0.9 or more to less than 0.95 - Cyan-1.0 or more to less
than 1.1
C: Black: 1.1 or more to less than 1.2 - Yellow: 0.7 or more to less than
0.8 - Magenta: 0.8 or more to less than 0.90 - Cyan: 0.9 or more to less
than 1.0
D: Black: less than 1.1 - Yellow: less than 0.7 - Magenta: less than 0.8
- Cyan: less than 0.9

The chart was recorded using Xerox 4024 (manufactured by Fuji
Xerox Co., Ltd.) in the same manner as in evaluating the image density,
and then printed block (■) portions were investigated with X-Rite 938 to
evaluate the color gamut using the following evaluation criteria. The
printer was run using the driver software supplied with the printer.

Before the printing, the printing mode was changed from "regular paper -
normal / fast" to "no color correction" in the user configuration menu for
regular paper. The ratio of the measured saturation to the saturation
(yellow- 91.34, magenta: 74.55 and cyan: 62.82) stated in the standard
color (Japan Color Ver. 2) was obtained to evaluate the color gamut using
the following evaluation criteria.

oA: 0.8 or more
B: less than 0.8

The chart was recorded using Type 6200 (manufactured by NBS
Ricoh Co., Ltd.) in the same manner as in evaluating the image density,
and then printed block (■) portions were dried under 23 °C and 50 %
relative humidity for 24 hours. The areas were soaked into 30 °C water
for 1 minute and carefully plucked from water, and then they were
allowed to dry naturally. Then, their water resistance was evaluated
using the following criteria.

oA: No ink exudation was recognized
B: Ink exudation was recognized

A chart document having a monochrome fill area which was 3 cm in
length and width, obtained using Microsoft Word 2000, was printed on
Ricoh Matte Glossy Paper for Geljet Printer (manufactured by NBS Ricoh

Co., Ltd.). The printed image was then dried under 23 °C and 50 %
relative humidity for 24 hours. The image portion was rubbed back and
forth 5 times with cotton (conforming to JIS L0803 standard) attached to
a CM-1 clock meter using a double-faced adhesive. Amount of
transferred ink from the image portion to that cotton was measured using
X-Rite 938. Based on the measured amount, the density of the
transferred ink on cotton was obtained and evaluated using the following
criteria. The effect of the original color of that cotton was eliminated for
obtaining the density.

A: less than 0.12
B: 0.12 or more

The chart was recorded using Type 6200 (manufactured by NBS
Ricoh Co., Ltd.) in the same manner as in evaluating the image density,
and then printed block (■) portions were dried under 23 °C and 50 %
relative humidity for 24 hours. The printed block portions were
subjected to a xenon irradiation at 0.35 W/m2 (340 nm) using Ci35AW (a
Weather-O'meter manufactured by Atlas Electric Devices Co.), which is
an approximated sunlight, for 24 hours under 70 °C, 50 % relative
humidity and 89 °C black panel temperature. The color deterioration
and change in color of the printed block portions before and after being
exposed to the xenon irradiation were measured and evaluated using the
following evaluation criteria.


A: Little deterioration and change were recognized
B: Deterioration and change were recognized while they were
allowable
C: Deterioration and change were too large to be allowed

The chart was recorded using Type 6200 (manufactured by NBS
Ricoh Co., Ltd.) in the same manner as in evaluating the image density,
and then filter paper was pressed against the printed block (■) portions
immediately after they were printed. The drying characteristic was
evaluated based on the degree of ink transferred to filter paper.

A: Transferred ink was not recognized on filter paper
□B: A small amount of ink transferred on filter paper
C: A large amount of ink transferred on filter paper

In a glass sample bottle, 20g of each ink prepared in Examples and
Comparative Examples was hermetically-sealed. The lid of the glass
sample bottle was further fastened and sealed with a vinyl tape, and then
the glass sample bottle was kept in a constant-temperature bath at 50 °C
for 1 month. Changes in the particle diameters was measured using
NANOTRAC UPA-EX 150 (a particle size analyzer manufactured by
NIKKISO Co., Ltd.). Percentage changes of the average particle
diameter (D50%) of the inks after they were stored against its initial

particle diameter were obtained using the following Equation 2.
«Equation 2»
Percentage change = [(Average particle diameter after stored /
average particle diameter before stored) - 1]*100

A: The percentage change was within plus/minus 10 % exclusively
B: The percentage change was plus/minus 10 % or more and within
plus/minus 20 % exclusively.
The percentage change was plus/minus 20 % or more
Table 5


Table 6

Images recorded using the inks of Comparative Examples 3, 6 and 7
were not as good as images recorded using other inks. Thus, they were
not evaluated.
Using the below mentioned recording papers (1) to (4) and the
recording inks of Examples 3 to 5, image quality evaluation tests were
performed as described below.
- Recording Paper (1) -
Trade name- AURORACOATE (commercially available paper having
a basis weight of 104.7 g/m2, manufactured by Nippon Paper Group, Inc.)
- Recording Paper (2) -
POD Gloss Coat 100 g/m2, manufactured by Oji paper Co., Ltd

- Recording Paper (3) -
Trade name: Super Fine Paper (commercially available matte coated
paper for inkjet printing, manufactured by Seiko Epson Corporation)
- Recording Paper (4) -
Trade name: Lumirror U10 (transparent polyester film having a
thickness of 100 µm, manufactured by TORAY Industries Inc.)
The transfer amount of purified water to each of the recording papers
(1) to (4) was measured as follows. The results are shown in Table 7.
Dynamic Scanning Absorptometer> .
Absorption curves of purified water to the recording papers (1) to (4)
were obtained using a dynamic scanning absorptometer (model: KS350D,
manufactured by Kyowa Seiko Co., Ltd.). The absorption curve was
obtained by plotting a sloped-straight line from the transfer amount
(mL/m2) and the square root of the contacting time. The transfer
amount after a certain period of time was determined by interpolation.
Table 7



Using the recording papers (l) to (4) and the recording inks of
Examples 3 to 5 in IPSIO G7570 (an inkjet recording apparatus
manufactured by Ricoh Company, Ltd.), image quality evaluation tests
were performed as described below. The results are shown in Table 8.
(1) Beading (Nonuniformity in Image Density)
The degrees of the nonuniformity in the image density of resulted
green fill areas were visually evaluated. For evaluation criteria, stepped
samples (grading from poor/1.0 to good/5.0) were used.
(2) Spur Marks
The frequency of the occurrences of offset-spur marks from resulted
red fill areas to background portions was visually evaluated. The
evaluation criteria and ranks are as follows.
Rank 1: Clearly recognized
Rank 2: Faintly recognized
Rank 3: Unrecognized
(3) Gloss Degree
Using a glossmeter (manufactured by BYK Gardner, 4501), the gloss
degree of resulted cyan fill areas at 60° was measured.
Table 8


printer/facsimile/copia composite machines.

CLAIMS
1. A recording ink, comprising:
a water-dispersible colorant,
a water-dispersible resin,
a wetting agent,
a surfactant, and
water,
wherein the content of the wetting agent in the recording ink is in the
range of from 20 % by mass to 35 % by mass,
the total solid content of the water-dispersible colorant and the
water-dispersible resin in the recording ink is in the range of from 12 %
by mass to 40 % by mass,
the water-dispersible resin contains fluorine resin particulates, and
the ratio A:B, where A is the solid content of the water-dispersible
resin in the recording ink and B is the solid content of a pigment
contained in the water-dispersible colorant in the recording ink, is in the
range of 0.5 to 8.
2. The recording ink according to Claim 1, wherein the
water-dispersible colorant contains at least a hydrophilic group at its
surface and is a pigment that is water-dispersible under the absence of a
dispersant.

3. The recording ink according to Claim 1, wherein the
water-dispersible colorant is a polymer emulsion that is composed of
polymer particulates containing a water-insoluble and/or hardly-soluble
coloring material.
4. The recording ink according to Claim 1, wherein
the water-dispersible colorant is a dispersed pigment containing a
pigment, a pigment dispersant and a polymer dispersion stabilizer, and
the polymer dispersion stabilizer is. any one of alpha-olefin/maleic
anhydride copolymer represented by the following structural formula (1),
styrene-(meth)acryl copolymers, water-soluble polyurethane resins and
water-soluble polyester resins.

Where R represents an alkyl group, and n represents an integer of 30
to 100.
5. The recording ink according to Claim 4, wherein
the polymer dispersion stabilizer has a weight average molecular
weight of 20,000 or lower and an acid value of 40 mgKOH/g to 400
mgKOH/g, and is dissolved in any one of an alkali solution and alkali

water-solution having an alkalinity value equivalent to or higher than the
acid value to be used.
6. The recording ink according to one of Claims 4 and 5, wherein the
pigment dispersant is an anion surfactant or a nonionic surfactant having
an HLB value of 10 to 20.
7. The recording ink according to Claim 6, wherein the nonionic
surfactant is anyone of polyoxyethylene-b-naphthylether,
polyoxyethylene laurylether and polyoxyethylene styrene phenylether.
8. The recording ink according to any one of Claims 1 to 7, wherein
the fluorine resin particulates contain a fluoroolefin unit and have a
minimum film forming temperature of 30 °C or lower.
9. The recording ink according to any one of Claims 1 to 8, wherein
the wetting agents is at least any one selected from glycerins, diethylene
glycol, triethylene glycol, 1,3-butanediol, 3-methyl-1,3-butanediol,
2-pyrrolidone and N-methyl-2-pyrrolidone.
10. The recording ink according to any one of Claims 1 to 9, wherein
the surfactant comprises at least one selected from silicone surfactants
and fluorine surfactants.

11. The recording ink according to any one of Claims 1 to 10, wherein
the viscosity thereof at 25 °C is in the range of from 5 mPa.s to 20 mPa.s,
and the surface tension thereof is 35 mN/m or lower.
12. An ink/media set, comprising:
the recording ink according to any one of Claims 1 to 11, and
a recording medium,
wherein the recording medium comprises a base and a coating layer
which is provided on at least one surface of the base, and
the transfer amount of pure water to the recording medium,
measured with a dynamic scanning absorptometer, is in the range of from
2 ml/m2 to 35 ml/m2 at a contacting time of 100 ms and in the range of
from 3 ml/m2 to 40 ml/m2 when measured at a contacting time of 400 ms.
13. An ink cartridge, comprising a container for housing the
recording ink according to any one of Claims 1 to 11.
14. An inkjet recording method, comprising ejecting drops of the
recording ink according to any one of Claims 1 to 11 by applying an
impulse thereto to record an image.
15. The inkjet recording method according to Claim 14, wherein the
impulse is at least any one selected from heat, pressure, vibration and
light.

16. An inkjet recording apparatus, comprising a means for ejecting
drops of the recording ink according to any one of Claims 1 to 11 by
applying an impulse thereto to record an image.
17. The inkjet recording apparatus inkjet recording method according
to Claim 16, wherein the impulse is at least any one selected from heat,
pressure, vibration and light.
18. An ink recorded matter, comprising:
a recording medium and an image formed on the. recording medium,
wherein the image is formed using the recording ink according to any
one of Claims 1 to 11.
19. An ink recorded matter, comprising:
the recording medium of the ink/media set according to Claim 12, and
an image formed on the recording medium, wherein the image is
formed using the recording ink of the ink/media set according to Claim 12.

To provide a recording ink which contains at least a water-dispersible colorant, a water-dispersible resin, a wetting
agent, a surfactant and water, wherein the content of the wetting agent in the recording ink is in the range of from 20 % by mass
to 35 % by mass, the total solid content of the water-dispersible colorant and the water-dispersible resin in the recording ink is in
the range of from 12 % by mass to 40 % by mass, the water-dispersible resin contains fluorine resin particulates, and the ratio A:B,
where A is the solid content of the water-dispersible resin in the recording ink and B is the solid content of a pigment contained in
the water-dispersible colorant in the recording ink, is in the range of 0.5 to 8.

Documents:

01691-kolnp-2008-abstract.pdf

01691-kolnp-2008-claims.pdf

01691-kolnp-2008-correspondence others.pdf

01691-kolnp-2008-description complete.pdf

01691-kolnp-2008-drawings.pdf

01691-kolnp-2008-form 1.pdf

01691-kolnp-2008-form 3.pdf

01691-kolnp-2008-form 5.pdf

01691-kolnp-2008-gpa.pdf

01691-kolnp-2008-international publication.pdf

01691-kolnp-2008-international search report.pdf

01691-kolnp-2008-pct priority document notification.pdf

01691-kolnp-2008-pct request form.pdf

1691-KOLNP-2008-(16-01-2012)-AMANDED CLAIMS.pdf

1691-KOLNP-2008-(16-01-2012)-CORRESPONDENCE.pdf

1691-KOLNP-2008-(16-01-2012)-DESCRIPTION (COMPLETE).pdf

1691-KOLNP-2008-(16-01-2012)-FORM 1.pdf

1691-KOLNP-2008-(16-01-2012)-FORM 13.pdf

1691-KOLNP-2008-(16-01-2012)-FORM 2.pdf

1691-KOLNP-2008-(16-01-2012)-OTHERS.pdf

1691-KOLNP-2008-(18-11-2011)-CORRESPONDENCE.pdf

1691-KOLNP-2008-ABSTRACT.pdf

1691-KOLNP-2008-AMANDED CLAIMS.pdf

1691-KOLNP-2008-AMANDED PAGES OF SPECIFICATION.pdf

1691-KOLNP-2008-ASSIGNMENT.pdf

1691-KOLNP-2008-ASSIGNMENT1.1.pdf

1691-KOLNP-2008-CORRESPONDENCE 1.1.pdf

1691-KOLNP-2008-CORRESPONDENCE.pdf

1691-KOLNP-2008-DESCRIPTION (COMPLETE).pdf

1691-KOLNP-2008-DRAWINGS.pdf

1691-KOLNP-2008-EXAMINATION REPORT REPLY RECIEVED.pdf

1691-KOLNP-2008-EXAMINATION REPORT.pdf

1691-KOLNP-2008-FORM 1.pdf

1691-KOLNP-2008-FORM 13.pdf

1691-KOLNP-2008-FORM 18.1.pdf

1691-kolnp-2008-form 18.pdf

1691-KOLNP-2008-FORM 2.pdf

1691-KOLNP-2008-FORM 3 1.1.pdf

1691-KOLNP-2008-FORM 3-1.2.pdf

1691-KOLNP-2008-FORM 3.pdf

1691-KOLNP-2008-FORM 5.pdf

1691-KOLNP-2008-GPA.pdf

1691-KOLNP-2008-GRANTED-ABSTRACT.pdf

1691-KOLNP-2008-GRANTED-CLAIMS.pdf

1691-KOLNP-2008-GRANTED-DESCRIPTION (COMPLETE) 1.1.pdf

1691-KOLNP-2008-GRANTED-DRAWINGS.pdf

1691-KOLNP-2008-GRANTED-FORM 1.pdf

1691-KOLNP-2008-GRANTED-FORM 2.pdf

1691-KOLNP-2008-GRANTED-SPECIFICATION.pdf

1691-KOLNP-2008-OTHERS.pdf

1691-KOLNP-2008-OTHERS1.1.pdf

1691-KOLNP-2008-PETITION UNDER RULE 137.pdf

1691-KOLNP-2008-REPLY TO EXAMINATION REPORT.pdf

abstract-1691-kolnp-2008.jpg


Patent Number 252453
Indian Patent Application Number 1691/KOLNP/2008
PG Journal Number 20/2012
Publication Date 18-May-2012
Grant Date 16-May-2012
Date of Filing 28-Apr-2008
Name of Patentee RICOH COMPANY, LTD.
Applicant Address 3-6, NAKAMAGOME, 1-CHOME, OHTA-KU, TOKYO, JAPAN
Inventors:
# Inventor's Name Inventor's Address
1 GOTO, HIROSHI PASTORAL GARDEN SANBANKAN 101, 265-1, TODA, ATSUGI-SHI, KANAGAWA 243-0023, JAPAN
PCT International Classification Number C09D 11/00,B41J 2/01
PCT International Application Number PCT/JP2007/066507
PCT International Filing date 2007-08-20
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2006-225431 2006-08-22 Japan