Crystal forms of quinacridones made from 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone
Novel crystal forms of solid solutions of 2,9-dimethyoxyquinacridone and 2,9-dichloroquinacridone. The crystal forms may be formed by a process comprising the steps of: a) heating a mixture of 2,5-di(4-methoxyanilino)terephthalic acid, and 2,5-di(4-chloroanilino)terephthalic acid in polyphorsphoric acid at a temperature less than 1050 C to form a mixture of 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone; b) combining the mixture of 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone with water; and c) heating the mixture of 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone at a temperature not more than 110° C. Another crystal form may be formed by the process of heating a mixture of 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone in a polar aprotic solvent. These products are may be used for coloring fibers, plastics, paints, coatings, printing inks, color filters, cosmetics, automotive coatings, textiles, fibers, powder coatings, in-mold coatings, laminate films, and the like.
1. A pigment comprising 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone, made by the process comprising the steps of:
a) heating a mixture of 2,5-di(4-methoxyanilino)terephthalic acid, and 2,5-di(4-chloroanilino)terephthalic acid in polyphosphoric acid at a temperature less than 105° C. to form a mixture of 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone;
b) combining the mixture of 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone with water; and
c) heating the mixture of 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone,
wherein the pigment comprises crystal form Type II, crystal form Type III, or a mixture thereof.
2. The pigment of claim 1 , where after step c, a presscake is formed by filtering the mixture of 2,9-dimethoxyquinacridone, 2,9-dichloroquinacridone, and water; the presscake is mixed with water, the pH of the mixture is adjusted to not less than about 12, and the presscake and water mixture is heated.
3. The pigment of claim 2 , where the presscake and water mixture is heated to a temperature greater than about 100° C.
4. The pigment of claim 1 , where the pigment in an automotive solvent basecoat/clearcoat paint system has CIE color coordinates of about 8.0≦a*≦ about 33.0, about −32.1≦b*≦ about −12.1, and about 19.0≦C*≦ about 41.0.
5. The pigment of claim 1 , where the pigment in an automotive solvent basecoat/clearcoat paint system has CIE color coordinates of about 10.0≦a*≦ about 31.0, about −25.0≦b*≦ about −17.0, and about 22.0≦C*≦ about 39.0.
6. The pigment of claim 1 , where the pigment comprises from about 10% to about 90% of 2,9-dimethoxyquinacridone and from about 90% to about 10% of 2,9-dichloroquinacridone.
7. The pigment of claim 1 , where the pigment comprises from about 25% to about 75% of 2,9-dimethoxyquinacridone and from about 75% to about 25% of 2,9-dichloroquinacridone.
8. The pigment of claim 1 , where the pigment has X-ray powder diffraction d-values at about 3.4 Å, about 4.2 Å, about 6.4 Å, about 8.3 Å, and about 16.7 Å.
9. The pigment of claim 1 , where the pigment is less than 10 ppb solvent extractable.
10. A pigment comprising 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone, that comprises crystal form Type II.
11. A pigment comprising 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone, that comprises crystal form Type I and II.
12. A process comprising the steps of:
a) heating a mixture of 2,5-di(4-methoxyanilino)terephthalic acid, and 2,5-di(4-chloroanilino)terephthalic acid in polyphosphoric acid at a temperature less than 105° C. to form a mixture of 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone;
b) combining the mixture of 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone with water; and
c) heating the mixture of 2,9-dimethoxyquinacridone and 2,9-dichloroquinacridone at a temperature not more than 110° C.
13. The process of claim 12 further comprising a step after step c of: forming a presscake by filtering the mixture of 2,9-dimethoxyquinacridone, 2,9-dichloroquinacridone, and water; the presscake is mixed with water, the pH of the mixture is adjusted to not less than about 12, and the presscake and water mixture is heated.