Quinacridone mixtures, process for their manufacture and their use as pigments

Compositions of linear trans-quinacridones containing at least one component (I) selected from unsubstituted, chloro- and methyl-substituted quinacridone and at least one component (II) selected from bis-(carbamoyl)-quinacridones, the carbamoyl groups of which are unsubstituted, N-mono-alkyl substituted or N,N-dialkyl-substituted, are pigments useful for coloring plastics and especially lacquers. These compositions are preferably prepared by joint ring closure of the corresponding 2,5-dianilino-terephthalic acids or esters.

The present invention relates to mixtures of compounds comprising at least 
one component of the formula (I) 
##STR1## 
wherein R.sup.1 and R.sup.2 are the same or different and stand for 
hydrogen, chlorine or methyl, and at least one component of the formula 
(II) 
##STR2## 
wherein R.sup.3 is --NH--R.sup.4 or --N(R.sup.5).sub.2 with R.sup.4 being 
hydrogen or alkyl of 1 to 6 carbon atoms and R.sup.5 being methyl or 
ethyl, to a process for their manufacture and to their use as pigments. 
The term "mixtures" includes also solid solutions of compounds of the 
formulae I and II. 
The compounds of the formula I are known. They can be prepared by 
cyclization of compounds of the formula (III) 
##STR3## 
in the presence of acid condensation agents (cf. French Pat. Nos. 
1,226,825 and 1,233,785; Belgian Pat. No. 611,271; Austrian Pat. No. 
218,651). Naturally only one of the radicals R.sup.1 and R.sup.2 of said 
formula can be in orthoposition with regard to the amino nitrogen, since 
one proton in ortho-position is split off in the cyclization. When both 
ortho-positions are unsubstituted, cyclization produces up to three 
isomers in the case of mono-substitution in metaposition, in the case of 
disubstitution in meta, para position and in the case of disubstitution in 
meta, meta position with different substituents. For example, the 
cyclization of the meta-chlorine derivative yields a mixture of 3,10-, 
1,8- and 1,10-dichloroquinacridone. 
Analogously, the 3,4-dichloroaniline derivative yields a mixture of 
2,3,9,10-, 2,3,8,9- and 1,2,8,9-tetrachloroquinacridone. 
Some of the compounds of formula II are known from German Pat. Nos. 
1,960,896 and 1,960,897. The compounds not disclosed in these publications 
can be prepared in analogous manner. In this case, too, isomers are 
obtained when --CO--R.sup.3 in the analogous starting compound of formula 
IV 
##STR4## 
is in the meta-position with regard to nitrogen. 
In any case the quinacridones can alternatively be prepared with lower 
alkyl esters of these terephthalic acids, instead of the acids as such, 
preferably the methyl and the ethyl esters. 
The mixtures according to the invention can be obtained by intimately 
mixing the components, but preferably are prepared by simultaneous 
cyclization of the compounds of the formulae III and IV or of the 
corresponding alkyl esters. 
Hence, the present invention also relates to a process for the preparation 
of the mixtures according to the invention, which comprises heating 
mixtures of compounds of the formulae III and IV or alkyl esters of these 
compounds having alkyl radicals with from 1 to 4 carbon atoms, in the 
presence of acid condensation agents. Naturally several compounds of the 
formulae III and/or IV can likewise be submitted to this simultaneous 
cyclization. Preferred embodiments of this preparation process will be 
described in detail hereinunder: 
A mixture consisting of from 30 to 95, preferably 50 to 95, parts by weight 
of a compound or compounds III and of from 5 to 70, preferably 5 to 50, 
parts by weight of a compound or compounds IV is heated in the presence of 
acid condensation agents. Heating is preferably carried out without the 
addition of diluents, in 2.5 to 10 times, in particular in 2.5 to 5 times, 
the quantity of polyphosphoric acid or an acidic lower polypolyphosphoric 
acid alkyl ester, this quantity being calculated on the weight of the 
compounds III and IV, to a temperature from 80.degree. to 150.degree. C., 
in particular from 100.degree. to 135.degree. C. The polyphosphoric acid 
preferably has a P.sub.2 O.sub.5 content of at least 81.5%. The preferred 
acidic polyphosphoric acid ester is a methyl ester having a P.sub.2 
O.sub.5 content of at least 79.5%. 
The melt of the cyclization product is thereafter hydrolyzed in water and, 
the precipitated quinacridone mixture is isolated, for example by 
filtration, and suitably washed to neutral with water. The water-moist 
crude quinacridone mixture is thereafter submitted to a treatment with 
organic solvents, or with mixtures of solvent and water, at a temperature 
of from 40.degree. to 150.degree. C., preferably 70.degree. to 135.degree. 
C., to convert it into an optimum pigment form. 
Suitable solvents for this purpose are those as described for example in 
German Pat. No. 1,262,106. However, preferred solvents are those that can 
be easily regenerated practically quantitatively from the pigment 
suspension after the treatment by simple distillation and that can be 
reused directly or after purification. Suitable solvents for this mode of 
operating are lower alcohols and ketones, for example methanol, ethanol, 
propanol, isopropanol, butanol, isobutanol, acetone, methylethylketone and 
methylisobutylketone. 
The properties of the pigment may be influenced favorably by wet grinding 
of the suspension of solvent, water and crude quinacridone, prior to or 
after the treatment at 40.degree. to 150.degree. C. Suitable wet grinding 
mills are colloid mills such as PUC mills, toothed attrition mills, 
agitator ball mills and similarly acting devices. The properties of the 
pigments may moreover be influenced favorably by the addition of 
surfactants and of resins or waxes during the hydrolysis of the 
cyclization product and/or during the solvent treatment of the crude 
quinacridone. 
The composition of the present invention suitably comprises 30 to 95%, 
preferably 50 to 95%, by weight of at least one component I of the formula 
##STR5## 
and 5 to 70%, preferably 5 to 50%, by weight of at least one component II 
of the formula 
##STR6## 
Examples of compositions in accordance with the claimed invention are as 
follows: 85% by weight of 2,9-dimethylquinacridone and 15% by weight of 
2,9-bis-(carbamoyl)-quinacridone; about 66.7% by weight of 
2,9-dimethyl-quinacridone and about 33.3% by weight of 
2,9-bis-(N-n-hexylcarbamoyl)-quinacridone; about 59% of 
2,9-dimethyl-quinacridone and about 41% of 
2,9-bis-(N-n-butyl-carbamoyl)-quinacridone; about 66.7% by weight of 
2,9-dimethyl-quinacridone and about 33.3% by weight of 
2,9-bis-(N-ethyl-carbamoyl)-quinacridone; about 66.7% by weight of 
2,9-dimethyl-quinacridone and about 33.3% by weight of 
2,9-bis-(N,N-dimethyl-carbamoyl)-quinacridone; about 84.5% by weight of 
2,9-dimethyl-quinacridone and about 15.5% by weight of a mixture of 3,10-, 
1,8- and 1,10-bis-(N-methyl-carbamoyl)- quinacridone as obtained by ring 
closure of 2,5,-bis-m-(N-methyl-carbamoyl)-anilino terephthalic acid; and 
94% by weight of 2,9-dimethyl-quinacridone and 6% by weight of 
2,9-bis-(carbamoyl)-quinacridone. 
The quinacridone mixtures according to the invention can be used as 
pigments. They give lacquer coatings of a high transparency and they are 
distinguished by excellent rheological properties, for example a low 
viscosity in lacquer systems. The fastness properties, in particular to 
light and to weathering, are at least equal to or superior to those of 
known quinacridones. Hence, the pigments according to the invention are 
suitable for use in the automobile field and in similar fields, where 
pigments of high transparency are required. 
The combination of high tinctorial strength and high transparency, which 
generally are due to a fine division of the pigment particles, with good 
rheological properties in the application medium is astonishing, since 
fine pigment particles usually involve a high absorption of binding agent 
and, consequently, a high viscosity of lacquers made with the pigment 
particles. Therefore, the pigments according to the invention are 
especially suitable for metallic lacquers. Moreover they may be used for 
the pigmentation of plastics because of the good processability of these 
pigments.

The following examples illustrate the invention. Parts and percentages are 
by weight. Temperatures are indicated in degrees Celsius (centigrade). 
EXAMPLE 1 
A mixture of 100 parts of 2,5-di-(4'-methylphenylamino)-terephthalic acid 
and 50 parts of 2,5-di-(4'-dimethylcarbamoyl-phenylamino)-terephthalic 
acid is added while stirring to 450 parts of an acidic polyphosphoric acid 
methyl ester (P.sub.2 O.sub.5 content about 80%), at 110.degree. to 
120.degree., in 1 hour. Stirring is continued for 2 hours at 125.degree. 
to 130.degree., whereupon the melt is hydrolyzed by pouring it into 1,350 
parts of 70.degree.-hot water, while stirring. The precipitated crude 
quinacridone is filtered off and washed to neutral with water. 
The neutral moist crude quinacridone is stirred into 900 parts of 
isobutanol (80%) and thereafter water is added until the total weight of 
the mixture is 1500 parts. The suspension is ground four times in a 
toothed attrition mill to give a pasty mixture that is refluxed for 10 
hours. Next, the isobutanol is distilled off and, the pigment is filtered 
off and dried. A bluish-red pigment results that is well-suited for 
incorporation in lacquer systems and yields highly transparent dyeings of 
high gloss and good fastness properties. 
EXAMPLE 2 
100 Parts of 2,5-di-(4'-methylphenylamino)-terephthalic acid and 50 parts 
of 2,5-di-(3'-N-dimethylcarbamoylphenyl-amino)-terephthalic acid are added 
while stirring to 450 parts of polyphosphoric acid (about 83.5% of P.sub.2 
O.sub.5), at 110.degree. to 120.degree. and stirring is continued for 2 
hours at 125.degree.. The melt is hydrolyzed while stirring in water of 
70.degree., the crude quinacridone is filtered off and washed acid-free 
with water. The crude quinacridone is stirred into 750 parts of ethanol 
and the weight of the mixture is made up to 1500 parts with water. Next, 
the suspension is ground twice in a colloid mill, then refluxed for 10 
hours and, subsequently, the ethanol is distilled off while adding 
simultaneously water in such an amount that the volume remains constant. 
At 60.degree. the pigment suspension is adjusted to slightly alkaline by 
adding a sodium carbonate solution, the suspension is stirred for 30 
minutes, and the pigment is filtered off, washed neutral and dried at 
80.degree.. 
The resulting bluish-red pigment can is suited for incorporation in lacquer 
systems. The highly transparent lacquer coatings exhibit a high gloss and 
good fastness properties. 
EXAMPLE 3 
A mixture of 140 parts of 2,5-di-(4'-methylphenylamino)-terephthalic acid 
and 40 parts of 2,5-di-(3'-carbamoyl-phenylamino)-terephthalic acid is 
cyclized in 450 parts of polyphosphoric acid and hydrolyzed in the manner 
described in Example 2. The neutral crude quinacridone is stirred into 900 
parts of isobutanol (80%), and the mixture is made up to a total weight of 
1500 parts with water and refluxed while stirring for 10 hours. Next, the 
isobutanol is distilled off with steam, the pigment suspension is adjusted 
to slightly alkaline with sodium carbonate solution, and the pigment is 
filtered off, washed and dried. The red-violet pigment is suitable for the 
pigmentation of lacquer systems. The lacquer coatings are very transparent 
and the lacquers are readily processed. 
When replacing in the solvent treatment the isobutanol by 
methylisobutylketone or by acetone and when stirring in a closed vessel at 
90.degree. for 10 hours, there is obtained a similar product. 
EXAMPLE 4 
Into 150 parts of polyphosphoric acid (about 83.5% of P.sub.2 O.sub.5) 
there are introduced while stirring 47 parts of 
2,5-di-(4'-methylphenylamino)-terephthalic acid and 3 parts of 
2,5-di-(4'-carbamoyl-phenylamino)-terephthalic acid at 120.degree., and 
stirring is continued for 2 hours at 125.degree.. The melt is thereafter 
poured while stirring into 450 parts of 70.degree.-hot water, wherein 3.5 
parts of resin soap (50%) have been dissolved with addition of a slight 
amount of an alkali, and the mixture is stirred for 30 minutes. After 
standing for several hours the crude quinacridone is filtered off and 
washed acid-free with water. The neutral crude quinacridone is stirred 
into 250 parts of isobutanol (100%), and the weight of the suspension is 
made up to 500 parts with water, whereupon the suspension is ground 
intensely in a high-efficiency disperser for 5 minutes and refluxed for 10 
hours while stirring. The alcohol is distilled off with steam, and the 
pigment is filtered off from the suspension, washed and dried. The 
bluish-red pigment can be readily processed in lacquers and has excellent 
fastness properties. 
EXAMPLE 5 
A mixture of 57.6 parts of 
2,5-di-(40'-N-ethylcarbamoyl-phenylamino)-terephthalic acid and 115.2 
parts of 2,5-di-(4'-methylphenylamino)-terephthalic acid is added while 
stirring to 600 parts of an acidic polyphosphoric acid methyl ester 
(P.sub.2 O.sub.5 content about 80%), at 125.degree. in 1 and a half hours. 
Stirring is continued for 2 hours at 130.degree. C., whereupon the mixture 
is poured into a 70.degree.-hot, slightly alkaline solution of 13 parts of 
resin soap (50%) and 1,800 parts of water, while stirring. The 
precipitated crude quinacridone is separated by filtration and washed 
neutral with water. The moist crude quinacridone is stirred into a mixture 
of 960 parts of water, 20 parts of potassium hydroxide and 400 parts of 
isobutanol (80%), ground twice in a colloid mill and subsequently stirred 
in a closed vessel for 5 hours at 125.degree.. Next, the isobutanol is 
distilled off, and the pigment is filtered off, washed and dried. The 
red-violet pigment is distinguished by a pure shade, excellent fastness 
properties, high gloss and good transparency of the lacquer coatings 
produced therewith. 
EXAMPLE 6 
27 Parts of 2,5-di-(3'-N-methylcarbamoylphenylamino)-terephthalic acid and 
150 parts of 2,5-di-(4'-methylphenyl-amino)-terephthalic acid are cyclized 
in 500 parts of polyphosphoric acid (P.sub.2 O.sub.5 content about 83.5%), 
at 125.degree.. The melt is hydrolyzed in 1,350 parts of water wherein 10 
parts of resin soap (50%) have been dissolved with addition of a slight 
amount of an alkali. The crude quinacridone is isolated and washed 
acid-free with water. 
The moist crude quinacridone is stirred in 720 parts of isobutanol (100%) 
and 180 parts of water in a closed vessel for 5 hours at 125.degree.. 
After distilling off the isobutanol with steam, the pigment is isolated 
and dried. 
The red-violet pigment is suitable for the pigmentation of lacquer systems. 
The lacquer coatings show a high transparency. 
EXAMPLE 7 
When proceeding as described in Example 6, with the exception that a 
mixture of 120 parts of 2,5-di-(4'-methylphenylamino)-terephthalic acid 
and 60 parts of 2,5-di-(4'-N-n-hexylcarbamoylphenylamino)-terephthalic 
acid is cyclized and that the isobutanolic crude quinacridone suspension 
is submitted to intensive grinding in a colloid mill, toothed attrition 
mill or agitator ball mill, prior to being heated to 125.degree., there is 
obtained a red-violet pigment of comparable quality. 
EXAMPLE 8 
50 Parts of 2,5-di-(4'-methylphenylamino)-terephthalic acid and 8.8 parts 
of 2,5-di-(4'-carbamoylphenylamino)- terephthalic acid are introduced into 
150 parts of an acidic polyphosphoric acid methyl ester (P.sub.2 O.sub.5 
content about 80%) while stirring at 120.degree. and the mixture is 
stirred for 2 hours at 125.degree. to 130.degree.. The cyclization product 
is thereafter poured into a stirred 70.degree.-hot slightly alkaline 
solution of 450 parts of water and 3.5 parts of resin soap (50%). The 
precipitated crude quinacridone is filtered off and washed neutral. The 
moist crude quinacridone is stirred in 300 parts of isobutanol (80%) and 
the total of the suspension is made up to 500 parts with water. This 
suspension is ground intensively in a high-efficiency disperser and 
subsequently boiled for 10 hours. The isobutanol is removed with steam and 
the pigment is filtered off directly or after the addition of sodium 
hydroxide solution in such an amount that the suspension has a pH of 9, 
washed subsequently neutral with water and dried. 
The bluish-red pigment has good rheological properties, yields transparent 
lacquer coatings and is very suitable for use in the automobile field. 
The following corresponding quinacridone mixtures are obtained in the 
manner described in Example 8 by cyclization of the dianilinoterephthalic 
acid mixtures lised in the following Table. These mixtures have the same 
good properties as those obtained in Example 8. 
TABLE 
______________________________________ 
Ex- 
ample Mixture of diarylamino terephthalic 
Shade of the 
No. acids (in parts by weight) 
pigment 
______________________________________ 
9 50 2,5-di-(4'-methylphenylamino)- 
bluish-red 
terephthalic acid 
8.8 2,5-di-(3'-N--diethylcarbamoyl- 
phenylamino)-terephthalic acid 
10 20 2,5-di-(4'-N--isobutylcarbamoyl- 
" 
phenylamino)-terephthalic acid 
40 2,5-di-(4'-methylphenylamino)- 
terephthalic acid 
11 33.5 2,5-di-(4'-methylphenylamino)- 
red-violet 
terephthalic acid 
23.5 2,5-di-(4'-N--n-butylcarbamoyl- 
phenylamino)-terephthalic acid 
12 50 2,5-di-(4'methylphenylamino)- 
bluish-red 
terephthalic acid 
8.8 2,5-di-(4'-diethylcarbamoyl- 
phenylamino)-terephthalic acid 
13 50 2,5-di-(4'-methylphenylamino)- 
" 
terephthalic acid 
8.8 2,5-di-(4'-N--dimethylcarbamoyl- 
phenylamino)-terephthalic acid 
14 45 2,5-diphenylamino-terephthalic acid 
" 
11 2,5-di-(4'-dimethylcarbamoyl- 
phenylamino)-terephthalic acid 
15 50 2,5-di-(4'-methylphenylamino)- 
" 
terephthalic acid 
9 2,5-di-(4'-N--n-propylcarbamoyl- 
phenylamino)-terephthalic acid 
16 45 2,5-di-(4'-methyl-3'-chloro-phenyl- 
" 
amino)-terephthalic acid 
11 2,5-di-(4'-dimethylcarbamoyl- 
phenylamino)-terephthalic acid 
______________________________________ 
EXAMPLE 17 
A mixture of 7 parts of 2,5-di-(4'-chlorophenylamino)-terephthalic acid and 
3 parts of 2,5-di-(4'carbamoylphenyl-amino)-terephthalic acid is cyclized 
in 70 parts of polyphosphoric acid (P.sub.2 O.sub.5 content about 83.5%), 
at 125.degree. to 135.degree. followed by hydrolyzation in 225 parts of 
water of 70.degree.. The isolated neutral water-moist crude quinacridone 
is suspended in 20 parts of ethanol and 40 parts of water, ground in a 
toothed attrition mill and stirred for 3 hours at 100.degree.. Next, the 
ethanol is distilled off, the pH of the pigment suspension is adjusted to 
9 with sodium hydroxide solution and the pigment is isolated, washed 
neutral and dried. The bluish-red pigment has excellent rheological 
properties and yields transparent lacquer coatings of excellent fastness 
properties. 
EXAMPLE 18 
10 Parts of 2,5-di-(3'-chlorophenylamino)-terephthalic acid and 2 parts of 
2,5-di-(4'-carbamoylphenylamino)-terephthalic acid are cyclized at 
130.degree. in 60 parts of an acidic polyphosphoric acid methyl ester 
(about 81.5% of P.sub.2 O.sub.5) and subsequently hydrolyzed. The isolated 
neutral crude quinacridone mixture is stirred in 60 parts of methanol and 
300 parts of water and ground intensively in a high-efficiency disperser. 
The suspension is stirred for 3 hours at 110.degree. in a closed vessel 
and cooled to 60.degree.. Thereafter the methanol is distilled off, the pH 
of the mixture is adjusted to 9 with NaOH and, the pigment is isolated, 
washed neutral and dried. The red pigment can be readily processed and 
yields transparent lacquer coatings. 
EXAMPLE 19 
8.8 Parts of 2,5-di-(4'-N-methylcarbamoylphenylamino)-terephthalic acid and 
50 parts of 2,5-di-(4'-methylphenyl-amino)-terephthalic acid are cyclized 
in the manner described in Example 8. The neutral moist crude quinacridone 
is stirred in 150 parts of isobutanol (80%), 150 parts of water and 10 
parts of phosphoric acid (85%) for 16 hours at room temperature and boiled 
subsequently for 10 hours. The pigment isolated in the manner described in 
Example 8 is distinguished by a high transparency and good processability 
in lacquer systems.