|Title of Invention||
"A METHOD FOR PREPARING A FLUSH PIGMENT OR INK PRODUCT"
|Abstract||^ ABSTRAg "A METHOD FOR PREPARING A FLUSH PIGMENT OR INK PRODUCT" A method for preparing an organic pigment dispersion, sucli as a flush pigment or ink product, comprises steps of introducing into a twin screw extruder a stable, water-borne pigment dispersion, an organic medium, and a destabilizing agent; mixing together the stable, water-borne pigment dispersion, the organic medium, and the destabilizing agent to produce a pigment flush phase and a water phase; and removing at least a part of the water phase. A twin-screw extruder for carrying out the flushing method has an addition and flushing zone, a water removal zone, and a zone for rinsing the crude organic pigment dispersion or flush with water and removing the rinse water. Additional materials may be added to form a finished pigmented product such as an ink product, masterbatch, or toner. 23|
|Full Text||FIELD OF THE INVENTION
 The invention relates to processes for preparing organic
pigment dispersions, including pigment flushes, and pigmented compositions
such as ink compositions. The present invention also relates to methods for
preparing ink bases and finished ink compositions.
BACKGROUND OF THE INVENTION
 Syntheses of many organic pigments include a coupling step in
a dilute aqueous medium to produce a slurry of the pigment product, which is
typically followed by a step of filtering the slurry in a filter press to concentrate
the pigment. The press cake that results is then either dried to provide a dry,
particulate pigment or else is "flushed" with an organic medium such as an oil or
resin to transfer the pigment particles from the aqueous press cake to the oil or
resin phase. The flushing process requires additional time and materials over
simply drying the pigment. If the pigment is used in an ink or coating
composition, however, it must first be well-dispersed in an appropriate organic
medium in order to achieve the desired color development and stability, and thus
the flushing process is advantageous because it accomplishes the transfer
without intermediate steps of drying the pigment and grinding the pigment in the
organic medium to produce the pigment dispersion.
 In the past, pigment flushes have usually been prepared by
batch processes in which the press cake is kneaded with an organic phase such
as an oil or a resin, for example in a sigma blade mixer or dough mixer, to flush
the pigment particles from the water phase to the organic medium phase and
displace the water as a separate aqueous phase. The displaced water is
decanted and the dispersion of the pigment in the varnish can be used as a
pigment paste in preparing an ink or paint.
 The batch process has many shortcomings. The steps of
adding varnish, kneading the dough to displace the water, and pouring off the
water must usually be repeated a number of times in order to obtain the
maximum yield from the flusher. This is a labor-intensive process that requires
careful monitoring. Further, in order to remove the residual water, the batch
must be heated and stripped under vacuum. For many pigments, the heat
history from processing to remove the residual water results in a color shift.
Because the precise heat history may vary from batch to batch, it is difficult to
reliably and accurately reproduce the same color from batch to batch. One of
the most significant shortcomings of the batch process is the lot to lot
fluctuations of the pigment and the solids content of the presscake. Further, the
process is time-consuming and inefficient. It is difficult to reduce the water
content below about 3% by weight, even with the vacuum stripping. Finally, the
pigment content of presscake, and therefore of the flush can vary.
 Continuous processes for preparing pigment flushes using
presscake have been proposed. In particular, the processes described in U.S.
Patents No. 6,273,599, 6,305,838, and 6,348,091, each of which is incorporated
herein by reference, have been highly successful in resolving some of the
shortcomings associatdd with batch flushing processes. U.S. Patent 5,262,268
describes using presscake to produce a toner in a twin-screw extruder.
SUMMARY OF THE INVENTION
 The present invention provides a process for continuous
production of organic pigment dispersion, such as pigment flush, or an ink
product in which a pigment is introduced into a twin screw extruder as a stable,
aqueous pigment dispersion, which can resolve the issue of lot to lot
pigment/color and solids variations of presscake. A stable dispersion is one that
has a usefully long shelf life without settling or becoming unpumpable. The
stable pigment dispersion can be destabilized with a destabilizing agent.
 in one embodiment of the invention, the stable pigment
dispersion is fed at a desired rate into the extruder along with a destabilizing
agent that precipitates the dispersed pigment. An organic medium, which may
include organic components selected from solvent, vamish, oil, polymer,
dispersant, and/or resin, is also fed into the extruder. The destabilized or
precipitated pigment and organic medium are mixed in a first zone of the
extruder to wet the pigment with the organic medium, displacing water from the
pigment and producing an organic pigment dispersion, such as a crude pigment
flush. At least a portion of the displaced water is removed in a second zone of
the extruder. The second zone of the extruder includes a port for removing the
displaced water, especially by draining the water, and preferably includes a dam
that retains the organic pigment dispersion or pigment flush in the second zone
for a time sufficient to allow most of the displaced water to be removed from the
crude flush mass. A third zone has additional ports for adding rinsing water,
particularly to remove salts or other by-products of the pigment destabilization or
precipitation, and for draining the removing the rinsing water. The extruder may
include a fourth zone that has one or more vacuum ports to draw off residual
water clinging to the organic pigment dispersion or pigment flush. The extruder
may have additional zones for introducing further materials for making a final
pigment dispersion or ink product, such as resins, oils, solvents, dispersants,
waxes, surfactants, and pigment or ink additives.
 In a second embodiment, the invention also provides a method
for continuous production of an ink base or a finished ink from a stable, aqueous
pigment dispersion. The method includes the steps just outlined for the process
of the invention for producing a pigment flush and at least one an additional step
of introducing into the extruder, at some point before the discharge outlet,
preferably after the optional vacuum zone, one or more additional ink
components, such as a varnish, pigmented tinting or toning compositions,
solvent, and/or additives, to make an ink base or a finished ink composition.
 In one embodiment, the stable, aqueous pigment dispersion
has a pigment content of at least about 25% by weight.
 In another embodiment, the stable, aqueous pigment dispersion
is stabilized by an ionic dispersant, and the destabilizing agent is an ionic agent.
In one embodiment, the dispersant may have carboxylic acid groups that are
salted to stabilize the aqueous dispersion, and that are destabilized with a protic
or Lewis acid.
 In one embodiment of the first zone, the stable pigment
dispersion and destabilizing agent are introduced into the extruder at a first point
barrel. The stable pigment dispersion and destabilizing agent are mixed in the
extruder to produce an aqueous destabilized pigment material The organic
medium is introduced into the extruder at a second point or downstream barrel of
the first zone and mixed with the destabilized pigment material to produce an
organic pigment dispersion phase and a water phase.
 In a second embodiment of the first zone, the stable pigment
dispersion, destabilizing agent, and organic medium are all introduced into a first
barrel of the extruder.
 In one embodiment of the process, the aqueous, stable,
pigment dispersion is substantially destabilized with the destabilizing agent
before the organic medium is introduced into the extruder. In an alternative
embodiment, the organic dispersion is introduced into the extruder before the
aqueous, stable pigment dispersion is substantially destabilized in the extruder.
 In certain embodiments of the invention, a toner product is
made by using as the organic medium a toner vehicle, typically a solid polymer
or resin with a low melting point.
 In certain embodiments of the invention, a masterbatch is made
by using as the organic medium a polymer such as polyethylene homopolymers
and copolymers, acrylonitrile butadiene styrene copolymer, polybutene,
polystyrene, polyphenylene oxide, polycarbonate, polypropylene, and the like
optionally with a resin of low melt viscosity such as a hydrocarbon, terpene, or
 "A" and "an" as used herein indicate "at least one" of the item is
present; a plurality of such items may be present, when possible. "About" when
applied to values indicates that the calculation or the measurement allows some
slight imprecision in the value (w'rth some approach to exactness in the value;
approximately or reasonably close to the value; nearly). If, for some reason, the
imprecision provided by "about" Is not otherwise understood in the art with this
ordinary meaning, then "about" as used herein indicates a possible variation of
up to 5% in the value.
BRIEF DESCRIPTION OF THE DRAWINGS
 FIGURE 11s a schematic diagram of one extruder configuration
for carrying out an embodiment of the inventive process; and
 FIGURE 2 is a schematic diagram of an alternative
configuration for the first four barrels of the extruder of FIGURE 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 The following description of the preferred embodiments) is
merely exemplary in nature and is in no way intended to Itmft the invention, its
application, or uses.
 The inventive method for continuous production of organic
pigment dispersions, pigment flush, or an ink product or other pigmented product
employs a stable, water-borne pigment dispersion that is introduced into a twin
screw extruder and destabilized in the extruder. The destabilized or precipitated
pigment is mixed or flushed with an organic medium. The separate water phase
may then be removed from the organic pigment dispersion phase.
 One example of a preferred extruder configuration has at least
four zones, and optionally has a fifth zone or further zones, in a first zone,
represented in the FIGURE 1 by barrels 1 through 3, the stable, aqueous
pigment dispersion, organic medium, and destabilizing agent are fed into the
extruder (barrel 1) and then mixed to destabilize or precipitate the pigment and
flush or remove the pigment from the aqueous phase to the organic phase
(barrels 2 and 3). The destabilizing agent is fed in separately from, and
preferably after, the pigment dispersion. In a second zone, represented by
barrels 4 and 5, at least a portion of the water displaced during the flushing stage
in the first zone is removed by draining or drawing the liquid from the extruder.
In a third zone, represented by the end of barrel 5 and barrels 6, 7A, 8, and 7,
rinse water may be Introduced to rinse any impurity, such as a salt precipitated
by interaction of the destabilizing agent and a salted dispersant resin of the
aqueous pigment dispersion, from the organic pigment dispersion or pigment
flush mixture, the rinse water being removed by draining or drawing the liquid
from the extruder through a port. In a fourth zone, represented by sections 9
through 11, residual water may be removed (as water vapor) by vacuum
dehydrating the organic pigment dispersion or pigment flush through vacuum
ports. The fourth zone may also have ports for introducing additives, resins, and
so as desired for the organic pigment dispersion, flush product, or ink or other
plgmented product. In a fifth, optional zone, represented by sections 12 through
14, the organic pigment dispersion or flush is further mixed and other
components may be added to the pigment dispersion or flush, as in the fourth
zone. Further ports may be used to introduce Ink components or other desired
materials in the fourth zone and/or optional fifth zone to produce an ink base,
finished ink composition, or other pigment product. Each zone may be heat or
cooled to a desired temperature for optimum mixing and preservation of the
pigment color properties. The product may be cooled before discharging.
 FIGURE 2 illustrates an alternative example of a first zone of
the extruder of FIGURE 1. In the alternative embodiment, the stable, aqueous
pigment dispersion and destabilizing agent are introduced and mixed in barrel 1.
Organic medium, shown in FIGURE 2 as polymer and dispersant, is introduced
in barrel 2. The pigment is destabilized or precipitated in barrel 1, and may form
a thick, presscake-like material. The destabilized pigment is then mixed with
organic medium in barrels 2 and 3 to incorporate the pigment into the organic
medium, forming an organic pigment dispersion and displacing a water phase.
Processing of the organic pigment dispersion continues through the second,
third, optional fourth, and optional fifth zones as before.
 In a first step of a first-embodiment of the method, a stable,
water-based pigment dispersion, organic medium, and destabilizing agent are
introduced into a first zone of the extruder. A stable, water-based pigment
dispersion may be prepared in any of a number of known methods. The pigment
used to make the stable, water-borne pigment dispersion may be, for example,
in the form of an aqueous slurry, a presscake, a dry crude pigment or activated
crude pigment, or a dry pigment. The pigment is stabilized in the aqueous
dispersion with a polymeric, oiigomeric, and/or monomeric dispersant or
combination of dispersants. The dispersant(s), base for salting the
dispersant(s), and water (as needed) are combined with the pigment to form a
stable, water-borne pigment dispersion of a desired pigment content.
 Any of a number of organic pigments may be used to form the
stable dispersion. Suitable examples include, without limitation, azo pigments
such as lithol reds (e.g., calcium lithol red, barium Irthol red), rubine reds, and
naphtho! reds, oranges, and browns; monoarylide and diarylide pigments such
as diarylide yellow, phthalocyanine blue and green pigments, azomethine
pigments, methine pigments, anthraquinone pigments, perinone pigments,
peryiene pigments, diketopyrrolopyrrole pigments, thioindigo pigments,
iminoisoindoline pigments, iminoisoindoiinone pigments, quinacridone pigments
such as quinacridone reds and violets, flavanthrone pigments, indanthrone
pigments, anthrapyrimidine pigments, carbazole pigments such as carbazole
violet, benzimidazolone yellows, tolyi orange, naphthol orange, and
quinophthalone pigments, and so on.
 Examples of useful ionic dispersants that may be used in
producing the stable, aqueous pigment dispersions include, without limitation,
fatty acids (e.g., lauroyi acid, tall oil fatty acid, oleic acid, linoleic acid, linolenic
acid, palmitic acid, stearic acid, and oleic acid); alkyibenzenesulfonates; alkyl
sulfates such as dioctylsutfosuccinat.es; ionic resins such as alkyd resins,
polyesters, rosins and modified rosins such as unsaturated acid- (e.g., maleio,
fumaric-, acrylic-, methacryllc-, crotonic-) modified rosins, dimerized rosins,
disproportionated rosins, hydrogenated rosins, phenolic-modified rosins, other
maleic- or fumariomodified polymers, acid-functional vinyl resins including acidfunctional
acrylic polymers, phenolic-acrylic polymers, and styrene-maleic
anhydride (SMA) copoiymers, low molecular weight, acid-functional
potyurethanes, and other stabilizing materials used or useful for preparing
dispersions that are pH sensitive or that may be destabilized in the extruder by
another material. The dispersants may be used in any stable combination. The
ionic resins are salted with a suitable counterion to provide water solubility or
dispersibiiity. Acid-functional dispersants may be salted with bases, e.g., sodium
hydroxide, ammonium hydroxide, potassium hydroxide, and mono- and dialkyl
amines. The water-based dispersions may also include other additives useful
for making organic pigment compositions or flush color such as oils (vegetable
and petroleum), anttoxidants, defoamers, surfactants, so-called pigment or
hyper-pigment dispersants, and non-dispersant resins.
 The stable, water-based pigment dispersions are preferably at
least about 25% by weight pigment, more preferably at least about 35% by
weight pigment. The pigment content of the stable dispersion depends on both
the pigment and dispersant selected, and may exceed 50% by weight, or even
60% by weight, and still be water-thin. The organic pigment dispersions typically
have a pigment content by weight of from about 25% to about 50% by weight.
TJ.e stable, water-based pigment dispersions may contain from 6 to about 40
parts by weight of ionic dispersant per 100 parts by weight of pigment.
 The stable, water-based pigment dispersion may be prepared
as an extension of tho pigment synthesis, by treatment of a pigment slurry, or by
post-dispersion of s presscake or dry pigment, e.g. in high-speed dispersers,
rotor-stators, basket mills, or pigment grinding mills.
 The organic medium into which the pigment is to be dispersed
or flushed is sufficiently hydrophobic to allow a non-aqueous phase to form in the
process. Types of organic materials that are suitable to prepare pigment flushes
are well-known in the art. The organic medium may be fed through the same
port as the stable, water-borne pigment dispersion, but it is r. ^ferabfy fed into
the extruder through a separate port.
 Typical lands of resins and oils that may be used for flushing
varnishes include, without limitation, alkyd resins, phenolic resins, polyesters,
hydrocarbon resins, maleic resins, rosin-modified varnishes of any of these,
polyamide resins, polyvinyl chloride resins, vinyl acetate resins, vinyl
chloride/vinyl acetate copolymer resins, chlorinated polyolefins, polystyrene
resins, acrylic resins, polyurethane resins, ketone resins, vegetable oils including
linseed oil, soybean oil, neatsfoot oil, coconut oil, tung oil, mineral oils, and so
on. Combinations of such resins and oils may also be employed. The resin, oil,
or combination thereof may be combined with a hydrophobic organic solvent or
liquid, including high boiling petroleum distillates.
 Typical kinds of organic materials that may be used to form
organic pigment dispersions for toners include but are not limited to polyamides,
epoxies, diolefins, potyurethanes, vinyl resins and polymeric esterification
products of a dicarboxylic acid and a diol comprising a diphenol. Among suitable
vinyl resins are those having as monomeric units styrene, p-chlorostyrene, vinyl
naphthalene, ethylene, propylene, butylene, and isobutylene, vinyl chloride, vinyl
bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl
butyrate, methyl acrylate, dodecyl acryiate, n-octyl acrylate, 2- chloroethyl
acrylate, phenyl acrylate, methylalphachloroacrylate, methyl methacrylate, ethyl
methacryiate, butyl methacrylate, acrylonitrile, methacrylonitrile, acrylimide, vinyl
methyl ether, vinyl isobutyl ether, vinyl ethyl ether, vinyl methyl ketone, vinyl
hexyl ketone, methyl isopropenyl ketone, vinylidene chloride, vinylidene
chlorofluoride, N-vinyl indole, and N-vinyl pyrrolidone, as well as styrene
 Typical kinds of organic materials that may be used to make
masterbatches include, without limitation, polymers such as polyethylene
homopolymers and copolymers, polypropylene homopolymers and copolymers,
acrylonitrile butadiene styrene copolymer, polystyrene, polyphenylene oxide,
polycarbonate, polyacrylate, and the like. These polymers may be used in
conjunction with a low molecular weight resin such as a hydrocarbon resin, rosin,
or terpene resin.
 In the first embodiment, the stable, water-based pigment
dispersion is fed into a first zone of the extruder, along with the organic medium
and a separate feed of a destabilizing agent. The aqueous pigment dispersion,
precipitating agent, and organic medium can be added at controlled, consistent
rates for production of consistent flush product For example, they may each be
fed from a line or tank, which may have a stirrer, and may be metered in with, for
example, a pump.
 Preferably, the organic medium, stable, water-borne pigment
dispersion, and destabilizing agent are each introduced at fairly constant rates.
The relative amounts of the organic medium and the pigment of the water-based
pigment dispersion for optimum processing can be determined based upon the
particular materials chosen, but in general the amounts remain the same as
those expected for conventional batch flushing processes. For example, the
amount of organic medium introduced per unit of time may be from about 0.6 to
about 3 times the amount of solid pigment introduced in the same unit of time.
The ratio of organic medium to solid pigment may be adjusted according to
factors known in the art, such as the type of pigment and the type of organic
medium and may be controlled by the automated process controls.
 The water-based pigment dispersion is destabilized, and the
pigment is released or precipitated, by the addition of the destabilizing agent.
The destabilizing agent is selected based on the nature of the stabilization of the
pigment dispersion. For example, when the pigment dispersion is prepared
using pH-sensitive dispersant, for example a salted, anionic resin, a destabilizing
agent that alters the pH, for example to acidic pH, is effective. Typical kinds of
destabilizing agent that may be added include protic acids and Lewis acids such
as hydrochloric acid, sulfuric acid, phosophoric acid, phosphonic acid, acetic
acid, formic acid, and aluminum chloride. These destabilizing agents may be
added in combination, and other, weaker acids (e.g., calcium chloride, strontium
chloride) may be added in combination with stronger acids. The destabilizing
agent is preferably chosen so that any excess destabilizing agent and any salts
produced by the interaction of the destabilizing agent with the water-borne
pigment dispersant can be removed by washing or by evaporation.
 In a second embodiment of the invention, the stable, waterbased
pigment dispersion and separate feed of destabilizing agent are
introduced into the extruder, mixed, and then, at a downstream point, the organic
medium is added In this embodiment, the water-based pigment dispersion is
first substantially destabilized with the destabilizing agent before the organic
medium is added. The destabilized aqueous pigment dispersion may have a
high viscosity that is advantageous for mixing with a high viscosity polymer melt,
such as may be used in making a masterbateh,
 A twin-screw extruder used in a preferred embodiment of the
method is shown in FIGURE 1. The first zone comprises screw elements for
mixing the destabilized, aqueous pigment and the organic medium. The
destabilized, aqueous pigment is thought to be like a high solids presscake in the
extruder, and the first zone should include one or more elements for high shear
mixing. Referring again to the FIGURE 1, Barrel 1 has four separate ports for
introduction (in preferred order) of stable, aqueous pigment dispersion, an alkyd,
a varnish, and an acidic destabilizing agent. Barrel 1 contains feed screw
elements. Barrel 2 contains combined mixing or kneading screw and conveying
screw elements. Barrel 3 contains combined high shearing mixing and
conveying screw elements. Barrels 2 through 4 may be heated with an oil jacket
held at about 60°C. The pigment mixture in barrel 2 may be about 45°C, but
may reach almost 90°C due to heat generated by the flushing shear.
 In an alternative embodiment shown in FIGURE 2, Barrel 1 has
two separate parts for introduction of stable, aqueous pigment dispersion and
destabilizing agent, while Barrel 2 has two separate ports for introduction of a
polymer and a dispersant. Optionally, a further barrel may be introduced before
Barrel 4 for longer mixing before separation of the aqueous phase.
 In one preferred embodiment of the invention, the screw profile
in the first zone tapers from a deep channel used in the section or sections
having a feeding port gradually to a shallow channel in a later (downstream)
section or section of the first zone. The length of the first zone of the extruder in
which the destabilized aqueous pigment and the organic medium are mixed is
sufficiently long so that the pigment is flushed completely. The rotational speed
of the screw also is a factor for efficient flushing. A preferred range for rotational
speed of the screw is from about 150 to about 550 rpm, and a more preferred
range for rotational speed is from about 250 to about 350 rpm. Because of the
high pigment concentration, the flushing zone of the extruder may be relatively
short as compared to a flushing zone needed for lower aqueous pigment
 The displaced water and the crude organic pigment dispersion
or pigment flush continue in the extruder to a second zone of the extruder where
at least a portion of the displaced water is removed. Preferably a major portion
of the displaced water Is removed in the second zone, more preferably at least
about 80%, still more preferably at least about 90%, and even more preferably
ail but a. residual amount of water that clings to the pigment flush is removed.
Referring to the FIGURE 1, barrel 4 includes an outlet for removing water
displaced in the flushing zone, preferably by draining the water off. While the
water may be withdrawn by other means, gravity draining is the simplest and is,
therefore, preferred. The outlet or port may contain a separate length of screw
turned by a motor that drives the relatively viscous pigment-containing flush back
into the barrel section while letting the water drain out, as describe in
Patents No. 6,273,599, 6,305,838, and 6,348,091.
 The second zone preferably has a dam downstream of the
water drain or outlet that retains the organic pigment dispersion or pigment flush
for a time sufficient to allow most of the displaced water to drain from the crude
organic pigment dispersion or flush mass. The dam causes the kneaded
pigment/organic medium to dwell over the port long enough to allow more of the
displaced water to drain from the kneaded pigment. A portion of the mixture of
pigment and organic medium is carried into the dammed section of the extruder
and remains in that section until the portion works its way out of the pocket of
retained material and Is carried into the next section by the grabbing action of the
screw. Such dam is described in more detail in U.S. Patents No. 6,273,599,
6,305,838, and 6,348,091. in brief, at least one screw element downstream of
the outlet, in barrel 5 of FIGURE 1, is reverse-threaded in a tight thread to
provide sufficient reverse flow to cause the material to fill the area having the
outlet. The reverse flow force that causes the damming effect is limited so that
there is no squeezing, as squeezing would tend to produce an emulsion of the
aqueous and organic phases, impairing the desired separation of water from
organic phase. The effect of the reverse flow is to cause material to accumulate
before eventually flowing over the created dam and/or being pulled on by
forward-turning screws located further downstream. The water is not engaged by
the forward screws and does not flow over the accumulated material. Instead,
the water is held in the second zone to drain. Because more of the water is
drained from the flush in a liquid phase instead of being evaporated, as
compared to prior methods, the final product contains a lower concentration of
salts. The dam thus improves the purity of the product.
 It is preferred, as illustrated in FIGURE 1, to introduce rinse
water into the crude flush in a third zone to rinse any water miscibie or soluble
impurities, particularly any salt precipitated by interaction of the destabilizing
agent and a salted dispersant resin of the aqueous pigment dispersion, from the
pigment dispersion or flush mixture that may be retained in the crude dispersion
or flush. The rinse water may also, of course, remove impurities that were
contained in the water-based pigment dispersion; thus, the water-based pigment
dispersion can have a high or low impurity or salt content that can be washed out
in the extruder. Typically, the water may be added at a rate of 60 to 150% of
that of the pigment addition rate to the extruder. The rinse water (preferably
introduced through a port in the top of the extruder) may be mixed with the crude
flush product in one or more barrels of the third zone and then be removed by
draining or drawing the liquid from the extruder through a port, as in the second
zone. Again, as in the second zone, it is preferred to create a dam by
introducing reverse-threaded (or left-hand) screw elements downstream from the
port or drain. If both a second and third zone are described, then at least the
third zone should include such a dam to minimize the residual water in the
organic pigment dispersion or flush product that exits the third zone, in one
preferred embodiment of the invention, the screw profile in the third zone tapers
from a deep channel used in the section or sections having a feeding port
gradually to a shallow channel in a later (downstream) section or section of the
third zone. The length of the third zone of the extruder in which the preflushed
pigment and wash are mixed is sufficiently iong to remove undesirable water
immiscible impurities from the pigment.
 In FIGURE 1, a third zone begins with a inlet port at the end of
barrel 5 for adding rinse water. Barrels 6 and 7A contain mixing and conveying
screw elements, and Barrel 8 contains mixing elements and the rinse water
outlet preferably configured as the outlet described for barrel 4. One or more of
the mixing elements may Include a plurality of kneading disks. Barrel 7B may
contain the reverse-threaded screw element or elements. Barrels 5 through 8
may be jacketed with an oil jacket held at about 60°C. The pigment mixture in
barrel 5 may be about 80°C or higher, and may reach about as high as 120°C in
 In FIGURE 1, a fourth zone is shown by barrels 9-11, which
include conveying screw elements and two vacuum ports for removing residual
water as water vapor. This zone is optional but preferred, and includes one or
more vacuum ports to draw off residual water clinging to the pigment flush. The
water is drawn off as water vapor. Suitable vacuum ports are known to be used
with extruders and typically can include a section containing a screw turned by a
motor in the vacuum port to help retain the flush in the extruder, as described in
U.S. Patents No. 6,273,599, 6,305,838, and 6,348,091. A vacuum pump is
typically connected to the vacuum port to provide the reduced pressure. The
profile of the screw used for the vacuum section preferably has a shallow
channel, which tends to increase the efficiency of vacuum dehydration by
shaping the material in a thin layer form. FIGURE 1 shows identical vacuum
ports on consecutive extruder sections. Barrels 9 through 11 may be jacketed
with a hot oil jacket held at about 40C. The evaporation and lower jacket
temperature should be expected to cool the material in the extruder; in barrel 9 it
may be about 70°C or higher, and by barrel 11 it may be as high as about 90°C.
 Barrel 9 in FIGURE 1 shows an inlet, by which a desired
additive, resin, solvent, or other material may be added to obtain the desired
flush or ink product composition, toner, masterbatch, or other pigmented
composition. Likewise, barrels 12 and 13 illustrate ports for addition of solvent,
varnish, additive, as shown, and/or other materials desired in the composition of
the final flush, ink product, toner, masterbatch, or other pigmented composition.
Barrels 12 to 14 are shown with a chilled water jacket for cooling the product
before discharge. The cooling water jacket may be 35-40°C, so that the product
exiting the extruder may be at 65°C or lower. This last zone of the extruder may
be as long or short as need to introduce the desired materials, with effective
mixing, and to cool the product.
 The process of the invention produces more consistent product
with less need for adjustment of parameters during the flush process.
 The pigment flush produced by the inventive process may be
used to prepare an ink composition according to usual methods. Alternatively,
the pigment flush may be made into an ink base or a finished ink composition in
the continuous process of the invention by introducing additional materials such
as varnish, other resins, organic solvent and/or additives into the extruder at
some point before the pigment flush is discharged, preferably after the vacuum
zone. The flushed pigment dispersion and other ink component(s) are combined
in the extruder so that the output from the extruder is an ink base or ink
composition. Typical resins used as ink varnishes that may be added include,
without limitation, alkyd resins, polyesters, phenolic resins, rosins, cellulosics,
and derivatives of these such as rosin-modified phenolics, phenolic-modified
rosins, hydrocarbon-modified rosins, maleic modified rosin, fumaric modified
rosins; hydrocarbon resins, vinyl resins including acrylic resins, poiyvinyl chloride
resins, vinyl acetate resins, polystyrene, and copolymers thereof; polyurethanes,
potyamide resins, and so on. Combinations of such resins may also be
employed. Suitable example of organic solvents that may be added include,
without limitation, aliphatic hydrocarbons such as petroleum distillate fractions
and normal and isoparaffmic solvents with limited aromatic character. Any of the
many additives known in the art that may be included in the ink compositions of
the invention, so long as such additives do not significantly detract from the
benefits of the present invention. Illustrative examples of these include, without
limitation, pour point depressants, surfactants, wetting agents, waxes,
emulsifying agents and dispersing agents, defoamers, antioxidants, UV
absorbers, dryers (e.g., for formulations containing vegetable oils), flow agents
and other rheology modifiers, gloss enhancers, and anti-settling agents. When
included, additives are typically included in amounts of at least about 0.001% of
the ink composition, and the additives may be included in amounts of up to about
7% by weight or more of the ink composition.
 The toner produced by the process may have additional
materials such as silica, dispersants, charge control additives, stabilizers, waxes,
and so on added, preferably after the vacuum zone,
0048] The masterbatch produced by the process may likewise have
additional materials added, again preferably after the vacuum zone. Examples
of such additional materials include, without limitation, stabilizers, slip additives
and lubricants, nucleators, antioxidants, biocides, UV absorbers, hindered amine
stabilizers, antisatic agents, fillers, tackifying resins, and so on.
 In one important aspect of the invention, the extruder further
includes at least one monitoring apparatus that continually monitors a property of
the material being processed in the extruder. The apparatus measures the
property of the material and compares the value measured to a desired value for
the property. The apparatus then uses the comparison to adjust one or more
parameters of the process.
 The monitoring apparatus keeps the product of the extruder
usable. In this regard, because of the many properties and parameters involved
in producing the organic pigment dispersions, pigment flush, or !nk product or
other pigment product in a continuous process instead of in the batch processes
previously used, apparatuses that provide continuing monitoring of properties of
the material during the processing with automated or semi-automated
adjustment of processing parameters are important in order to avoid producing
large amounts of unusable off-specification material. The choice of adjustment is
preferably made according to predetermined logic and is made and applied to
the process by a computer processing unit or "programmable logic controller."
Suitable microprocessors that can be so programmed are known and need not
be described further here.
 "" monitoring apparatus may include one or more measuring
devices selected ..om spectrophotometers, viscometers, thermocouples, pH
meters, turbidity meters, conductivity meters, moisture content meters, particle
size analyzers, and combinations of these. The monitoring apparatus may also
include one or more control devices for the extruder selected from mass flow
meters, motor amp meters, devices that control the motor speed and/or the
screw rotation speed, devices that control the rate of feed of one or more feed
components, devices that begin or stop feed from auxiliary feed components,
devices that control the amount of vacuum applied, devices that control the
processing temperature at a point in the process, and combinations of these.
The monitoring apparatus may be located at any point along the extruder at an
outlet or in a sample loop. The monitoring apparatus is preferably located at the
exit of the extruder. The monitoring apparatus may include a diverter to isolate
out-of-specification material from the product stream until the value of the
measured property is again acceptable.
 Further details about preferred monitoring apparatus types and
their use may be found in U.S. Patent No. 6,348,091. It is preferred to use such
instruments to monitor one or more properties in the present process.
 The invention is illustrated by the following examples. The
examples are merely illustrative and do not in any way limit the scope of the
invention as described and claimed. AH parts are parts by weight unless
Example of the Invention.
 A twin screw co-rotating extruder with a screw diameter of 44
mm, 17D of 56, and a speed of 450 rpm is used to produce a pigment flush. The
(Table Removed)  A 44% by weight solids, water-based, blue dispersion is fed into
the first barrel of an extruder as shown in the RGURE at a rate of 117 !bs./hr
along with 56% acetic acid at a feed rate of 7.0 IbsThr., an alkyd and an organic
vehicle at a feed rate of 12 Ibs/hr., and a first hydrocarbon varnish at a feed rate
of 19.7 IbsThr. This mass is then mixed through the end of barrel 3. The
displaced water is drained from the pigment/varnish mass in barrel 4. The water
should be fairly clear. Water is then charged to the extruder at Barrel 5 at a flow
rate of 80 IbsThr. The crude flush product and water are mixed in barrels 6 and
7A, and the water is drained from the extruder in barrel 8. Barrels 9 to
comprise a vacuum dehydration zone in which further, residual water is removed
from the flush product at barrels 9 and 11.
[00561 The flush is reduced by addition of 9.4 Ibs/hr of a hydrocarbon
varnish and 8.8 Ibs/hr of a hydrocarbon oil in Barrels 12 and 13. The pigment
flush is allowed to cool. The pigment flush, hydrocarbon varnish and
hydrocarbon oil are further mixed and cooled in Section 14. The resulting
product is a shade converted flush with less than 2% water content.
 The description of the invention is merely exemplary in nature
and, thus, variations that do not depart from the gist of the invention are intended
to be within the scope of the invention. Such variations are not to be regarded
as a departure from the spirit and scope of the invention.
^ WE CLAIM:
1. A method for preparing a flush pigment or ink product, comprising
introducing into a first barrel of a first zone of twin screw extruder a stable, waterborne
pigment dispersion that has a pigment content of at least 25% by weight, an
organic medium, and a destabilizing agent;
mixing together in the first zone the stable, water-borne pigment dispersion, the
organic medium, and the destabilizing agent to produce a pigment flush phase and a
water phase; and
removing at least a part of the water phase in a second zone of the extruder.
2. A method as claimed in claim 1, wherein the organic medium comprises a member
selected from the group consisting of organic solvents, varnishes, oils, resins, and
3. A method as claimed in claim 1 , further comprising a step of adding one or more ink
components selected from the group consisting of varnishes, pigmented tinting and
toning compositions, organic solvents, ink additives, and combinations thereof.
4. A method as claimed in claim 1, wherein the stable, water-borne pigment dispersion
is stabilized by an ionic dispersant, and the destabilizing agent is an ionic agent.
5. A method as claimed in claim 4, wherein the ionic dispersant has salted carboxylic
acid groups and the destabilizing agent is selected from the group consisting of
protic acids and Lewis acids.
6. A method of producing a pigmented product, comprising steps of feeding a stable,
water-borne pigment dispersion into a twin screw extruder and destabilizing the
dispersion in the extruder to produce an aqueous precipitated pigment; and flushing
the precipitated pigment in the extruder with an organic medium.
7. A method for preparing an organic pigment dispersion or pigmented product,
comprising steps of
^ introducing into a twin screw extruder a stable, water-borne pigment dispersion that
has a pigment content of at least 25% by weight and a destabilizing agent;
mixing together the stable, water-borne pigment dispersion and the destabilizing
agent to produce a substantially destabilized pigment;
introducing into the twin screw extruder an organic medium;
mixing together the substantially destabilized pigment and the organic medium to
produce an organic pigment dispersion phase and a water phase; and
removing at least a part of the water phase.
8. A method as claimed in claim 7, wherein the organic medium comprises an ink
9. A method as claimed in claim 7, wherein the organic medium comprises a toner
10. A method as claimed in claim 1, wherein the organic medium comprises at least one
of polyethylene homopolymers and copolymers, acrylonitrile butadiene styrene
copolymers, polybutenes, polystyrenes, polyphenylene oxides, polycarbonates,
polypropylenes, hydrocarbon resins, terpene resins, and rosin materials.
11. A method as claimed in claim 7, wherein the organic medium comprises a polymer
and a dispersant.
12. A method as claimed in claim 7, wherein the organic medium comprises at least one
of polyamides, epoxies, diolefins, polyurethanes, vinyl resins, and polymeric
esterification products of dicarboxylic acids and diol comprising a diphenol.
13. A method as claimed in claim 7, further comprising, after removing the water phase,
adding into the extruder at least one of silica, dispersants, charge control additives,
stabilizers, waxes, slip additives, lubricants, nucleators, antioxidants, biocides, UV
absorbers, hindered amine light stabilizers, antistatic agents, fillers, and tackifying
14. A method as claimed in claim 7, wherein the stable, water-borne pigment dispersion
is stabilized by an ionic dispersant, and the destabilizing agent is an ionic agent.
* 15. A method as claimed in claim 14, wherein the ionic dispersant has salted carboxylic
acid groups and the destabilizing agent is selected from the group consisting of
protic acids and Lewis acids.
16. A twin-screw extruder, comprising:
a first zone having inlets for an aqueous pigment dispersion feed, a destabilizing
agent feed, and an organic medium feed, feed screw elements, high shear mixing
screw elements, and conveying elements for flushing the pigment into the organic
medium and creating a water phase;
a second zone having an outlet for at least partially removing the water phase; and
a third zone with an inlet for adding water, mixing and conveying screw elements,
and an outlet for removing at least a part of the water.
17. A twin-screw extruder as claimed in claim 16, wherein at least one of the second
zone and the third zone has a partial dam that impedes the progress of the pigment
flush out of the zone for a desired time.
18. A twin-screw extruder as claimed in claim 16, wherein said inlets for adding aqueous
pigment dispersion, a destabilizing agent, and an organic medium are in one barrel
of the extruder.
19. A twin-screw extruder as claimed in claim 16, wherein said inlets for adding aqueous
pigment dispersion and a destabilizing agent are in a first barrel of the extruder and
said inlet for adding an organic medium is in a second, downstream barrel of the
Dated this 1' day of March, 2007
OF K &WPARTNERS
AGENT FOR THE APPLICANT(S)
|Indian Patent Application Number||1675/DELNP/2007|
|PG Journal Number||12/2014|
|Date of Filing||01-Mar-2007|
|Name of Patentee||FLINT GROUP INCORPORATED|
|Applicant Address||14909 N. BECK ROAD, PLYMOUTH, MICHIGAN 48170, UNITED STATES OF AMERICA|
|PCT International Classification Number||B01F11/00; C08K5/00|
|PCT International Application Number||PCT/US2005/029039|
|PCT International Filing date||2005-08-15|