Black perylene pigments

1. A black perylene pigment, comprising an isomer according to formula Ia, an isomer according to formula Ib, or a mixture thereof

wherein:

R 1 , R 2 are each independently phenylene, naphthylene or pyridylene, each of which may be mono- or polysubstituted by C 1 -C 12 -alkyl, C 1 -C 6 -alkoxy, hydroxyl, nitro and/or halogen;

X is halogen;

n is from 0 to 4; and

the pigment has a blackness value ≧210 when provided in an alkyd/melamine baking varnish.

2. The perylene pigment according to claim 1 , wherein;

R 1 and R 2 radicals are the same and are each selected from the group consisting of unsubstituted phenylene and naphthylene; and

R 1 and R 2 are the same.

3. A process for preparing the perylene pigment according to claim 1 , comprising:

obtaining a crude perylene pigment; and

subjecting the crude perylene pigment to a treatment selected from the group consisting of:

a) comminution;

b) comminution and recrystallization in a liquid medium; and

c) comminution with simultaneous recrystallization.

4. The process according to claim 3 , wherein the crude pigment is subjected to high-energy powder grinding.

5. The process according to claim 3 , wherein the crude pigment is initially subjected to dry grinding in the presence or absence of a salt as a grinding assistant and then to a-recrystallization in an organic solvent, under hot conditions.

6. The process according to claim 3 , wherein the crude pigment is subjected to kneading under hot conditions in the presence of an organic solid having recrystallizing action and &-an inorganic salt.

7. The process according to claim 3 , wherein the crude pigment is subjected to aqueous wet grinding in the presence of an organic solvent having recrystallizing action.

8. A process for preparing perylene pigments according to claim 1 , comprising:

obtaining a crude perylene pigment; and

subjecting the crude perylene pigment to swelling in a concentrated acid.

9. The process according to claim 3 , wherein obtaining the crude pigment comprises:

condensing perylene-3,4:9,10-tetracarboxylic dianhydride with an aromatic ortho- or peri-diamine; and

subsequently cyclizing in the presence of phenol or a nitrogen-containing, nonfused heteroaromatic;

wherein the aromatic ortho- or pen-diamine comprises at least one member selected from the group consisting of R 1 and R 2 .

10. The process according to claim 3 , wherein the process is carried out in the presence of a pigment synergist and/or a pigment additive.

11. The process according to claim 5 , wherein recrystallization is carried out in a mixture of the organic solvent and water.

12. The process according to claim 8 , wherein swelling is carried out subsequent to comminution.

13. A method, comprising:

coloring high molecular weight organic and inorganic materials of natural and synthetic origin with the perylene pigment according to claim 1 .

14. The process according to claim 13 , wherein the high molecular weight organic and inorganic materials are selected from the group consisting of coatings, inks toners, polymers, paints, plastics articles, glasses, silicatic layer systems and organic-inorganic composites.

15. A method, comprising:

coloring plastics articles that are used for laser penetration welding with the perylene pigment according to claim 1 .

16. A method, comprising:

coloring natural or synthetic leather materials with a perylene pigment according to claim 1 .

17. A method, comprising:

incorporating the perylene pigment according to claim 1 into a charge-generating material for electrophotography or a constituent of a black matrix in an LC display.

18. A method, comprising:

incorporating the perylene pigment according to claim 1 into a water-, polymer- or polyolefin wax-based pigment preparation.

19. A process for preparing a crude perylene pigment comprising an isomer of the formula Ia, an isomer of the formula Ib, or a mixture thereof

wherein:

R 1 , R 2 are each independently phenylene, naplithylene or pyridylene, each of which may be mono- or polysubstituted by C 1 -C 12 -alkyl, C 1 -C 6 -alkoxy, hydroxyl, nitro and/or halogen;

X is halogen; and

n is from 0 to 4;

the process comprising:

condensing perylene-3,4:9,10-tetracarboxylic dianhydride with an aromatic ortho-diamine; and

subsequently cyclizing;

wherein:

the aromatic ortho- or peri-diamine comprises at least one member selected from the group consisting of R 1 and R 2 ; and

condensing and cyclizing are carried out in phenol or a nitrogen-containing, nonfused heteroaromatic as a reaction medium.

20. The process according to claim 19 , wherein the process is carried out in the presence of a pigment synergist and/or a pigment additive.

21. A pigment synergist, comprising an isomer of the formula Ia′, an isomer of the formula Ib′, or a mixture thereof

wherein:

R 1 ′, R 2 ′ are each independently phenylene, naphthylene or pyridylene, each of which is mono- or polysubstituted by —COO— M+, —COOR3, —CONR 3 R 4 ,

—COO— N+R 3 R 4 R 5 R 6 , —SO 2 NR 3 R 4 , —CH 2 NR 3 R 4 , —CH 2 N+R 3 R 4 R 5 R 6 R 3 —COO − and/or —CH 2 R 7 , and may additionally be mono- or polysubstituted by C 1 —C 12 -alkyl, C 1 —C 6 -alkoxy, hydroxyl, nitro and/or halogen;

R 3 ,R 4 ,R 5 ,R 6 are each in dependently hydrogen; C 2 -C 12 -alkyl or C 2 -C 12-alkenyl whose hydrocarbon chain may in each case be interrupted by one or more —O—, —S—, —NR 8 —, —CO— or —SO 2 — moieties, and/or be mono- or polysubstituted by hydroxyl, halogen, aryl, C 1 -C 4 -alkoxy and/or acetyl; C 3 -C 8 -cycloalkyl whose carbon skeleton may be interrupted by one or more —O—, —S—, —NR 8 — or —CO— moieties, and/or be substituted by acetyl;

R 7 is phthalimidyl;

R 8 is hydrogen or C 1 -C 8 -alkyl;

M + is hydrogen or a metal cation;

X is halogen; and

n is from 0 to 4.