Preparation of polyhalocopper phthalocyanine pigments of high color strength

Polyhalocopper phthalocyanine pigments of high color strength are prepared by recrystallizing the finely divided agglomerated crude pigment in a heterogeneous aqueous organic phase at elevated temperatures by a process in which the aqueous organic phase used is a heterogeneous mixture of an aliphatic ketone having a total of 3 to 9 carbon atoms and water. The process gives the pigments in the form of spherical granules which are dust-free or have a low dust content. The pigments give deep, brilliant colorations of pure hues.

BACKGROUND OF THE INVENTION 
Field of the Invention 
The halogenation of copper phthalocyanine gives an amorphous to 
microcrystalline agglomerated crude polyhalocopper phthalocyanine which, 
because of the high degree of agglomeration is opaque and has a low color 
strength. For this reason, the crude pigment is converted by 
recrystallization into pigmentary forms having optimum color properties. 
This process, also referred to as conditioning or finishing, is carried 
out, for example, at elevated temperatures in 90-98% strength by weight 
sulfuric acid, in xylene (DE-B-No. 2,013,818), o-nitrophenol (DE-C-No. 
1,242,180) or in a mixture of benzoic acid and/or alkylbenzoic acids and 
water at from 80.degree. to 130.degree. C. (DE-A No. 3,442,118). 
Pigmentary forms having interesting color properties are obtained by heat 
treatment in o-nitrophenol. However, this conditioning medium has 
considerable disadvantages: it has a strong odor since it has a marked 
vapor pressure at as low as room temperature, it sublimes readily and it 
is volatile together with steam. Other disadvantages are that 
o-nitrophenol has a low melting point and marked solubility in water, 
resulting in losses during the recovery process. 
A further disadvantage is that the o-nitrophenolate anion formed in the 
removal of the nitrophenol by the addition of an alkali metal hydroxide 
has a high affinity for the polyhalocopper phthalocyanine pigment, so that 
a long wash process is required for substantially quantitative removal of 
the nitrophenolate. 
Finishing in xylene according to DE-B-No. 2,013,818, in which the 
pigmentary form is obtained directly in the form of a nonagglomerated 
powder by freeze-drying, must be carefully carried out and monitored to 
prevent supercrystallization. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a process for the 
conversion of polyhalocopper phthalocyanine which gives pigmentary forms 
having good color properties by an environmentally compatible process and 
makes it possible to prepare pigmentary forms optimally adapted to the 
various intended uses. 
We have found that this object is achieved by a process for the preparation 
of polyhalocopper phthalocyanine pigments of high color strength by 
recrystallizating the finely divided, agglomerated crude pigment in a 
heterogeneous, organic aqueous phase at elevated temperatures, wherein the 
organic aqueous phase used is a heterogeneous mixture of aliphatic ketones 
having a total of 3 to 9 carbon atoms and water. 
The process provides powder-soft polyhalocopper phthalocyanine pigments 
which give deep transparent, brilliant colorations having pure hues. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the process according to the invention, the pigments are obtained in the 
form of spherical granules having diameters up to 5 mm. The granules which 
contain from 60 to 70% by weight of pigment, the remainder being water and 
ketone in a weight ratio of about 3:2, can be dried, for example in a 
drying drum, with shape retention. The resulting granules have a low dust 
content and are readily dispersible. 
The process according to the invention is carried out in general as 
follows: the polyhalocopper phthalocyanine (polyhalo-CuPc) obtained in the 
synthesis is suspended in water in the form of the press cake, the ketone 
is added and the mixture is heated to the desired temperature. In the 
conversion to the pigmentary form comprising very uniform and compact 
crystals (particles), it is critical that the crude pigment is completely 
surrounded by the ketone. In the case of the water-soluble ketones, such 
as acetone and diethyl ketone, the formation of the heterogeneous phase is 
forced by the addition of salt. This can also be achieved by adding an 
alkali metal hydroxide solution. 
Suitable polyhalo-CuPc compounds are polychloro-CuPc having from 10 to 16 
chlorine atoms and polybromochloroCuPc having from 0 to 13, preferably 
from 4 to 12, chlorine atoms and from 14 to 2, preferably from 12 to 4, 
bromine atoms in the molecule. 
Examples of suitable aliphatic ketones are acetone, methyl ethyl ketone, 
diethyl ketone, methyl n-propyl ketone, methyl isopropyl ketone, methyl 
n-butyl ketone, methyl isobutyl ketone, methyl isoamyl ketone, diisopropyl 
ketone, di-n-propyl ketone, di-n-butyl ketone and diisobutyl ketone and 
mixtures of these. Among these, methyl ethyl ketone, methyl isobutyl 
ketone, methyl n-propyl ketone and methyl isopropyl ketone are preferred 
for technical reasons. Methyl isobutyl ketone is very particularly 
preferred. The weight ratio of crude pigment to ketone is in general from 
1:0.3 to 1:2.0, preferably from 1:0.3 to 1:1.5. 
The amount of water is not critical if the mixture is miscible before, 
during and after the crystallization; however, a large amount of water 
should be avoided since this reduces the space-time yield. As a rule, the 
weight of water used is from 3 to 4 times that of the crude pigment 
(calculated as dry substance). 
Where water-soluble or partially readily soluble ketones are used, a salt 
or an alkali metal hydroxide solution is added to the aqueous medium in 
order to form a second ketone-containing phase, which is required for the 
recrystallization. Suitable salts here are sodium chloride, potassium 
chloride, sodium sulfate and calcium chloride, preferably sodium chloride. 
The same effect can be obtained by adding sodium hydroxide solution or 
potassium hydroxide solution. 
Pigmentary forms which give particularly pure colorations having a high 
color strength are obtained if strong bases, such as sodium hydroxide 
solution or potassium hydroxide solution, are added to the aqueous 
mixture. The amount of these bases is chosen so that the aqueous phase is 
alkaline at the end of the finishing operation. 
The amount of these bases can be up to 2 parts by weight per 100 parts by 
weight of crude pigment. From 1 to 1.6 parts by weight of alkali metal 
hydroxide, such as sodium hydroxide or potassium hydroxide, are preferably 
used per 100 parts by weight of crude pigment. 
The recrystallization is carried out at the boiling point of the mixture, 
to 120.degree. C. Where temperatures above the boiling points of the 
azeotropic mixtures of ketone and water are used, the recrystallization is 
carried out under superatmospheric pressure. The procedure is preferably 
carried out at from 55.degree. to 105.degree. C., under atmospheric or 
superatmospheric pressure. When the mixture containing the crude pigment 
is stirred and heated, the pigment is obtained in the form of spherical 
granules having a diameter of about 0.5-5 mm. 
At the end of the crystallization, the granules can readily be isolated by 
decanting, but preferably by filtration under suction, and washing. The 
granules retain their form when dried. Drying is advantageously carried 
out in a drying drum. The mixture of ketone and water which is removed 
during the drying process is condensed, and worked up together with the 
filtrate and wash water obtained during isolation, to give the ketone. 
The conversion mixture can also be worked up by distilling the ketone 
directly from the conversion mixture, together with water in the form of 
an azeotrope, some of the granules breaking up. The pigment is then 
isolated from the aqueous phase in a conventional manner by filtration 
under suction, and is washed neutral with water and dried.

The Examples which follow illustrate the process. Parts and percentages are 
by weight. 
EXAMPLE 1 
In a stirred vessel, 75 parts of polybromochlorocopper phthalocyanine 
(chlorine content 7%, bromine content 58%) in the form of a 30% strength 
press cake are mixed with 45 parts of methyl isobutyl ketone and 4 parts 
of 20% strength sodium hydroxide solution, and the stirred mixture is 
refluxed. Flushing begins at about 80.degree. C.: the crude pigment passes 
into the organic phase with displacement of the water, spheres slowly 
forming from the ketone-rich solid mixture. 
After refluxing has been carried out for 12 hours (89.degree. C.), the 
ketone is distilled off. The recrystallized green pigment is filtered off, 
washed and dried. 
73 parts of green pigment which gives deep colorations having pure hues and 
high transparency are obtained. The resulting pigment has good powder 
softness and, in terms of color properties, is equivalent to that obtained 
by the prior art process. 
EXAMPLES 2 TO 8 
The procedure described in Example 1 is followed, except that, instead of 
methyl isobutyl ketone, the ketones stated below are used in the amount 
indicated and at the temperature given. The pigments obtained have 
virtually the same color properties. When acetone and diethyl ketone are 
used, sodium chloride is also added to achieve complete formation of the 
second phase, which is important for finishing. 
______________________________________ 
bp. of 
the 
azeo- 
Exam- bp. trope Amount 
ple Ketone (.degree.C.) 
(.degree.C.) 
of ketone 
NaCl 
______________________________________ 
2 Acetone 56 58 105 parts 
90 parts 
3 Methyl ethyl 79 73 107 parts 
-- 
4 Methy isopropyl 
92 78 60 parts 
-- 
5 Methyl n-propyl 
102 85 65 parts 
-- 
6 Diethyl 100 83 45 parts 
10 parts 
7 Diisopropyl 123 90 38 parts 
-- 
8 Methyl isoamyl 
144 95 34 parts 
-- 
______________________________________ 
EXAMPLE 9 
200 parts of crude polybromochloro-CuPc (containing 7% of Cl and 58% of 
Br), in the form of the 30% strength aqueous press cake, are stirred with 
260 parts of methyl ethyl ketone and 10 parts of 20% strength sodium 
hydroxide solution in an autoclave for 8 hours at 100.degree. C. 
Thereafter, the autoclave is let down, the ketone is distilled off and the 
pigment is isolated as in Example 1. 
194 parts of a green pigment are obtained which has very similar color 
properties and performance characteristics to the pigment obtained in 
Example 1. 
Working up the mixture after recrystallization can also be carried out as 
follows. After the pressure vessel has been cooled, the pigment granules 
are separated from the liquid phase by filtration, decanting or sieving, 
washed briefly with water to remove alkali and salt adhering to the 
surface (there are no ions enclosed in the granules; the conductivity test 
is negative) and dried. The resulting pigmentary form, which has a low 
dust content or is dust-free, can then be used directly, ie. without 
pulverization or milling. 
EXAMPLES 10 TO 16 
The procedure described in Example 9 is followed, except that the methyl 
ethyl ketone is replaced with the stated ketones in the amount indicated. 
The resulting green pigments have similar color properties and performance 
characteristics. 
______________________________________ 
Amount of Amount of 
Example 
Ketone ketone NaCl added 
______________________________________ 
10 Acetone 320 parts 150 parts 
11 Methyl isopropyl ketone 
160 parts -- 
12 Methyl n-propyl ketone 
160 parts -- 
13 Methyl isobutyl ketone 
120 parts -- 
14 Diethyl ketone 115 parts -- 
15 Diisopropyl ketone 
100 parts -- 
16 Methyl isoamyl ketone 
60 parts -- 
______________________________________ 
EXAMPLE 17 
In a stirred vessel, 100 parts of crude polybromochlorocopper 
phthalocyanine (containing 26% of Cl and 33% of bromine), in the form of 
the 30% strength aqueous press cake, are conditioned together with 60 
parts of methyl isobutyl ketone and 8 parts of 20% strength sodium 
hydroxide solution for 10 hours at the reflux temperature (89.degree. C.). 
Working up is carried out simllarly to Example 1 to give a powder-soft 
green pigment whose color properties correspond to those of the prior art 
pigments. Yield: 96%. 
EXAMPLE 18 
The procedure described in Example 17 is followed, except that 90 parts of 
methyl isopropyl ketone are used instead of 60 parts of methyl isobutyl 
ketone, and the crystallization is carried out in a pressure vessel at 
100.degree. C. The pigment granules isolated have performance 
characteristics and color properties similar to those of the pigment 
obtained according to Example 17. 
EXAMPLE 19 
100 parts of crude polychloro-CuPc (49.5% of Cl), in the form of a 33% 
strength aqueous press cake, 70 parts of methyl isobutyl ketone and 5 
parts of 20% strength NaOH are refluxed for 10 hours (89.degree. C.), 
while stirring. The resulting pigment granules are removed by sieving, 
washed with water and dried. 
95 parts of green pigment are obtained whose color strength, brilliance, 
purity, transparency and hue correspond to those of the prior art 
pigments. The ketone is recovered from the sieve liquid by distillation. 
EXAMPLE 20 
The procedure described in Example 19 is followed, except that 60 parts of 
diisopropyl ketone are used instead of 70 parts of methyl isobutyl ketone. 
The resulting green pigment has virtually the same color properties and 
performance characteristics as that obtained according to Example 19. 
EXAMPLE 21 
The procedure described in Example 19 is followed, except that 100 parts of 
diethyl ketone are used instead of 70 parts of methyl isobutyl ketone, and 
crystallization is carried out as described in Example 9 in a pressure 
vessel at 100.degree. C. The resulting pigment granules have color 
properties and performance characteristics similar to those of the pigment 
obtained according to Example 19. 
EXAMPLE 22 
If, instead of 70 parts of methyl isobutyl ketone, only 50 parts of methyl 
isoamyl ketone are used but the procedure is otherwise carried out 
similarly to Example 19, green pigments having very good color properties 
are obtained both at the reflux temperature (89.degree. C.) and under 
superatmospheric pressure at 100.degree. C.