U.S. patent application number 09/741389 was filed with the patent office on 2002-06-20 for process for preparing a substantially pure gamma phase quinacridone pigment of large particle size.
Invention is credited to Robertson, George H., Sung, Edward H., Velasquez, Humberto.
Application Number | 20020073896 09/741389 |
Document ID | / |
Family ID | 24980542 |
Filed Date | 2002-06-20 |
United States Patent
Application |
20020073896 |
Kind Code |
A1 |
Sung, Edward H. ; et
al. |
June 20, 2002 |
PROCESS FOR PREPARING A SUBSTANTIALLY PURE GAMMA PHASE QUINACRIDONE
PIGMENT OF LARGE PARTICLE SIZE
Abstract
An improved process for producing a substantially pure gamma
phase a quinacridone pigment or pigment derivative involving
preparing an aqueous slurry of a crude quinacridone in the presence
of caustic alkali and a non-polar, water immiscible solvent; and
heating said slurry at a temperature above about 120.degree. C.
Inventors: |
Sung, Edward H.;
(Cincinnati, OH) ; Robertson, George H.;
(Loveland, OH) ; Velasquez, Humberto; (Cincinnati,
OH) |
Correspondence
Address: |
Sidney Persley, Esquire
Sun Chemical Corporation
222 Bridge Plaza South
Fort Lee
NJ
07024
US
|
Family ID: |
24980542 |
Appl. No.: |
09/741389 |
Filed: |
December 20, 2000 |
Current U.S.
Class: |
106/497 ; 546/49;
546/56 |
Current CPC
Class: |
C09B 67/0027 20130101;
C07D 471/04 20130101; C09B 48/00 20130101 |
Class at
Publication: |
106/497 ; 546/49;
546/56 |
International
Class: |
C09B 048/00; C09B
048/00 |
Claims
What is claimed is:
1. A process for conditioning a quinacridone pigment or pigment
derivative comprising: (a) preparing an aqueous slurry of a crude
quinacridone in the presence of caustic alkali and a non-polar,
water immiscible solvent; and (b) heating said slurry at a
temperature above about 120.degree. C. resulting in a substantially
pure gamma phase quinacridone pigment of large particle size.
2. The process of claim 1 wherein the caustic alkali is selected
from the group consisting of sodium hydroxide, potassium hydroxide
and lithium hydroxide.
3. The process of claim 1 wherein the caustic alkali is sodium
hydroxide.
4. The process of claim 1 wherein the non-polar water immiscible
solvent is selected from the group consisting of mineral spirits,
xylene and alpha-olefins.
5. The process of claim 4 wherein the non-polar water immiscible
solvent is mineral spirits.
6. The process of claim 1 wherein said heating is carried out at a
temperature of about 120 to 170.degree. C.
7. The process of claim 1 wherein the crude quinacridone is used as
presscake containing 4 to 70 wt. % quinacridone pigment, with the
balance being essentially water.
8. The process of claim 1 wherein the gamma phase quinacridone
pigment is collected from said slurry by filtration after the
heating step.
9. A quinacridone pigment conditioned by the process of claim
1.
10. A printing ink comprising a quinacridone pigment conditioned by
the process of claim 1.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a conditioning process for
quinacridone pigment and quinacridone derivatives, useful as
colorants for printing inks. More particularly, the invention
relates to treatment of quinacridone and quinacridone derivatives
at elevated temperatures with caustic alkali and non-polar water
immiscible solvent to produce a substantially pure gamma phase
quinacridone pigment of large particle size.
BACKGROUND OF THE INVENTION
[0002] It is well known that opaque quinacridones of gamma phase
with a high covering power can be prepared from two different
approaches. One approach requires milling the large particle
quinacridone crude with salt or conditioning the extremely fine
quinacridone crude in solvent. For example, the cyclization of
2,5-dianilino-3,6-dihydroterephthalic acid or its methyl ester in
Dowthern A (available from Dow Chemical Co., Midland, Mich.) will
generate 6,13-dihydroquinacridone of large particle size. Oxidation
of 6,13-dihydroquinacridone in aqueous methanol in the presence of
sodium hydroxide yields a crude quinacridone which is subjected to
salt-milling. Quinacridone of gamma modification is then produced
by either treating the salt-milled material with various organic
solvents or milling the crude with inorganic salt in the presence
of an alcohol and a base.
[0003] In another approach, quinacridone crude can be prepared by
cyclizing 2,5-dianilinoterephthalic acid in strong acid, e.g.,
polyphosphoric acid or its acid methyl ester. The resulting crude
is extremely small and requires after-treatment to increase
particle size for arbitrary application.
[0004] Crude quinacridones are normally conditioned with organic
solvents to give dispersible pigments. For example, U.S. Pat. No.
4,895,948 discloses a one-step finishing process in which a crude
quinacridone is ball milled in an alcohol containing a base. U.S.
Pat. No. 5,084,573 also discloses a one-step finishing process in
which 2,9-dichloroquinacridone is stirred in heated polar organic
solvents containing, as essential ingredients, cedain long-chain
thiol compounds and a base. U.S. Pat. No. 5,095,056 discloses a
process for conditioning 2,9-dichloroquinacridone using large
quantities of polar solvents, including esters such as methyl
benzoate, at temperatures above 50.degree. C. Although bases and
other such additional compounds are not required, the polar solvent
is used in an amount that is about 3 to 20 times the weight of the
pigment. Water can be tolerated but is not preferred. U.S. Pat. No.
3,256,285 similarly discloses a process for finishing aqueous
pastes of quinacridones in large quantities of organic solvent (4
to 10 times the amount of pigment) at temperatures of 80.degree. to
150.degree. C. When using high-boiling or water-immiscible solvents
(such as methyl benzoate and methyl salicylate) according to U.S.
Pat. No. 3,256,285, the presscake must be washed with low boiling
organic solvents, thus requiring the disposal of significant
quantities of organic liquids which is more costly and time
consuming.
[0005] U.S. Pat. No. 5,383,966 describes the preparation of
quinacridone in methyl benzoate and aromatic esters (as the polar
organic solvent) in relatively small quantities and without the
need for special additives. However, the suitable quinacridone for
this method is specified as 2,9-dimethylquinacridone,
2,9-dicholoquinacridone or solid solution of either chemical with
unsubstituted quinacridone.
[0006] Furthermore, it is important to note that caustic alkali is
not used during the conditioning step in this method but rather is
added after conditioning to hydrolyze methyl benzoate. The solvent
used is methyl benzoate which is a polar solvent.
[0007] The present invention provides an improved and economic
method for preparing gamma phase quinacridone of large particle
size using caustic alkali and a non-polar water immiscible
solvent.
SUMMARY OF THE INVENTION
[0008] The present is an improved process for conditioning a
quinacridone pigment and quinacridone derivatives comprising: (a)
preparing an aqueous slurry of a crude quinacridone in the presence
of caustic alkali and a nonpolar, water immiscible solvent; and (b)
heating said slurry at a temperature above about 120.degree. C.
thereby producing a substantially pure gamma phase quinacridone
pigment.
DETAILED DESCRIPTION OF THE INVENTION
[0009] It has been surprisingly found that substantially pure gamma
crystal phase quinacridone pigment or derivative of large particle
size can be prepared by treating a crude quinacridone preparation
with water and caustic alkali in the presence of small amount of
non-polar, water immiscible, solvent at a temperature above about
120.degree. C., and more preferably from about 120.degree. C. to
about 170.degree. C., to give a soft and opaque pigment. The
addition of caustic alkali and non-polar, water immiscible solvent
is essential to the success of this invention. Elimination of
caustic from process prevents the complete conversion of the alpha
crude into the gamma modification and the removal of solvent
retards crystal conversion totally.
[0010] The crude quinacridone can be prepared in a number of ways.
Preferably, crude quinacridone is prepared by: (a) dissolving
2,5-dianilinoterephthalic acid in polyphosphoric acid (PPA), at a
temperature of about 90 to 130.degree. C. to result in a magma; and
(b) striking the resulting mixture (i.e. magma) into water to
precipitate alpha phase crude quinacridone.
[0011] While dissolving 2,5-dianilinoterephthalic acid in PPA, the
concentration and temperature of PPA are key elements affecting
product opacity and cleanness. A high PPA concentration and low
condensation temperature generally results in a crude which can be
opacified easier. The PPA concentration can be increased through
the addition of P.sub.2O.sub.5. It is preferable to maintain the
PPA concentration between 117% to 119% and to control the
condensation temperature at 90 to 120.degree. C. A lower PPA
concentration or higher condensation temperature will result in a
dark and poor dispersible pigment. After cyclization of
2,5-dianilinoterephthalic acid, the PPA mixture is then poured into
water to precipitate quinacridone crude.
[0012] Preferably, the resulting crude quinacridone is washed to
conductivity below 1000 mu, more preferably below 800 mu.
[0013] The purity of the 2,5-dianilinoterephthalic acid
intermediate often affects product quality and therefore must be
kept as high as possible. Major impurities such as
2-anilinoterephthalic acid and 2,5-dianilinobenzoic acid should be
eliminated or substantially reduced during the preparation of
intermediate. To maintain consistent quality of final pigment, the
purity of 2,5-dianilinoterephthalic acid is preferably 98.0% or
higher.
[0014] The crude quinacridone, which is in the form of alpha phase,
may be washed thoroughly with water before reslurrying back into
water. The filtercake must be broken down entirely to form a good
dispersion. Any undispersible lump will lead to a dark, dirty and
bluish material. The amount of water used should be enough to
provide a fluidable mass and is preferable 10 to 15 times the
pigment weight. Frequently, small amounts of surfactant can be
added to the slurry to improve dispersion.
[0015] Both organic and inorganic alkali may be used in the
conditioning process, but the caustic alkali such as sodium
hydroxide, potassium hydroxide or lithium hydroxide is preferred
due to their low cost. The alkali increases the ionic
characteristics of quinacridone and speeds up particle size growth
in water. The amount of caustic alkali is preferable at 0.3 to 0.8
times of pigment weight. Shortage of caustic would slow down the
opacification process and result in a dark and dull pigment.
Elimination of caustic from process prevents the complete
conversion of alpha crystal into gamma modification, in certain
case, such as at elevated temperature, part of alpha crystal can
even transform into beta crystal.
[0016] Various types of non-polar, water immiscible solvent, such
as xylene, alpha-olefin, textile spirits, mineral spirits and many
aliphatic hydrocarbon solvents can be applied in this invention.
Due to its water immiscible nature, it often encapsulates pigment
and forms bead-like particles. The physical condition of the
encapsulated pigment facilitates not only filtration speed but also
provides soft texture after drying. The amount of non-polar solvent
is preferable at about 0.1 to 2 part of pigment weight. Raising the
amount of solvent will not affect the pigment quality but simply
increasing the cost of production. However, the elimination of
solvent from this process would be detrimental to the product in
which the crude is unable to convert into gamma modification and
results in a dark and dull material.
[0017] The pigment slurry after addition of solvent is heated
slowly to a high temperature above 120.degree. C. The suitable
temperature is around 130-160.degree. C. and is preferable at
140-150.degree. C. The length of heating is depended on the level
of temperature and generally higher temperature requires less time
to achieve similar particle size. The mixture is then cooled to
60.degree. C. before filtration and the presscake is washed to
alkali free and dried to give an opaque, easy dispersible
quinacridone with gamma modification.
[0018] Pigment made from this invention possesses a cherryish red
with good covering power and its excellent light-fastness and heat
stability are of considerable industrial importance for pigmenting
finishes and paints and for coloring plastics.
[0019] Because of their light stability and migration properties,
the quinacridone pigments prepared according to the present
invention are suitable for many different pigment applications. For
example, pigments prepared according to the invention can be used
as the colorant (or as one of two or more colorants) for very
light-fast pigmented systems. Examples include pigmented mixtures
with other materials, pigment formulations, paints, printing ink,
colored paper, or colored macromolecular materials. The term
"mixtures with other materials" is understood to include, for
example, mixtures with inorganic white pigments, such as titanium
dioxide (rutile) or cement, or other inorganic pigments. Examples
of pigment formulations include flushed pastes with organic liquids
or pastes and dispersions with water, dispersants, and, if
appropriate, preservatives. Examples of paints in which pigments of
this invention can be used include, for example, physically or
oxidatively drying lacquers, stoving enamels, reactive paints,
two-component paints, solvent- or water-based paints, emulsion
paints for weatherproof coatings, and distempers. Printing inks
include those known Eor use in paper, textile, and tinplate
printing. Suitable macromolecular substances include those of a
natural origin, such as rubber; those obtained by chemical
modification, such as acetyl cellulose, cellulose butyrate, or
viscose; or those produced synthetically, such as polymers,
polyaddition products, and polycondensates. Examples of
synthetically produced macromolecular substances include plastic
materials, such as polyvinyl chloride, polyvinyl acetate, and
polyvinyl propionate; polyolefins, such as polethylene and
polypropylene; high molecular weight polyamides; polymers and
copolymers of acrylates, methacrylates, acrylonitrile, acrylamide,
butadiene, or styrene; polyurethanes; and polycarbonates. The
materials pigmented with the quinacridone pigments of the present
invention can have any desired shape or form.
[0020] The pigments prepared according to this invention are highly
water-resistant, oil-resistant, acid-resistant, lime-resistant,
alkali-resistant, solvent-resistant, fast to over-lacquering, fast
to over-spraying, fast to sublimation, heat-resistant, and
resistant to vulcanizing, yet give a very good tinctorial yield and
are readily dispersible (for example, in plastic materials such as
polyvinyl chloride and ABS).
[0021] The invention will be illustrated by the following specific
examples, but it is to be understood that it is not limited to the
details thereof and that changes may be made without departing from
the scope of the invention.
EXAMPLE 1
[0022] Polyphosphoric acid (PPA, 913.6 g) is heated to 90.degree.
C. and 2,5-dianilinoterephthalic acid (168 g) is added to it over
three hours. The PPA temperature is maintained between
90-105.degree. C. during addition and the mixture is hold at
100-105.degree. C. for additional half hours after addition. Twenty
four grams of water is then added to mixture slowly to dilute the
PPA and the temperature is maintained at 100-105.degree. C. The
diluted mixture is poured into water (3,336.00 g) at 10.degree. C.
and the resulting slurry is stirred for 3 hours to assure the
complete hydrolysis. The mixture is then filtered and washed with
water until free of acid.
[0023] The above presscake (30 g) is added to a Parr pressure
reactor, along with water (370 g), mineral spirits (30 g), 50%
sodium hydroxide (30 g) and Aerosol OT (1.5 g). The mixture is
mixed thoroughly for 3 minutes and is heated slowly to 150.degree.
C. The temperature is held at 150.degree. C. for an additional 4
hours and is cooled to 60.degree. C. before filtration. The
filtercake is then washed with water until pH is less than 9. The
presscake is then dried at 80.degree. C. and after grinding, it
gives a soft, opaque pigment of gamma formation.
EXAMPLE 2
[0024] Example 1 is repeated. After addition of crude, water,
mineral spirits and Aerosol OT in pressure reactor, the mixture is
simply mixed with agitator without the homogenization. The pigment
slurry is then heated slowly to 150.degree. C. and the temperature
is held at 150.degree. C. for additional 4 hours. The reaction
mixture is cooled to 60.degree. C. and is filtered. The filtercake
is then washed with water until pH is less than 9. The presscake is
then dried at 80.degree. C. and after grinding, it gives a product
which is slightly darker, bluer and dirtier than that made from
Example 1.
EXAMPLE 3
(COMPARATIVE)
[0025] Crude presscake (30 g, dry basis) is added to a Parr
pressure reactor, along with water (370 g) , 50% sodium hydroxide
(30 g) and Aerosol OT (1.5 g). The mixture is mixed for 3 minutes
(no mineral spirits is added) and is heated slowly to 150.degree.
C. The temperature is held at 150.degree. C. for an additional 4
hours and is cooled to 60.degree. C. before filtration. The
filtercake is washed with water until pH is less than 9. The
presscake is then dried at 80.degree. C. and after grinding, it
gives a considerable dull, dark pigment of predominate alpha
formation.
EXAMPLE 4
(COMPARATIVE)
[0026] Crude presscake (30 g, dry basis) is added to a Parr
pressure reactor, along with water (370 g), mineral spirits (30 g)
and Aerosol OT (1.5 g). The mixture is mixed thoroughly for 3
minutes and is heated slowly to 150.degree. C. The temperature is
held at 150.degree. C. for an additional 4 hours and is cooled to
60.degree. C. before filtration. The filtercake is washed with
water until pH is less than 9. The presscake is dried at 80.degree.
C. and after grinding, it gives a considerable dull, dark pigment
of mix crystals which contain both gamma and alpha formation and 4
to 5% of beta formation.
[0027] The invention has been described in terms of preferred
embodiments thereof, but is more broadly applicable as will be
understood by those skilled in the art. The scope of the invention
is only limited by the following claims.
* * * * *