Process for preparing quinacridone pigments

Details Process for preparing quinacridone pigments Process for preparing quinacridone pigments

1997-04-01

1998-05-26

Bell, Mark L.

Compositions: coating or plastic

Materials or ingredients

Pigment, filler, or aggregate compositions, e.g., stone,...

106493, 106494, 106497, 546 49, 546 56, C09B 6752

Patent

active

057558728

ABSTRACT:
A process for preparing quinacridone pigments
A process for preparing pigments, mixed crystal pigments and pigment preparations based on linear unsubstituted or substituted quinacridones of the formula (I) ##STR1## in which the substituents R.sup.1 and R.sup.2 are identical or different and are hydrogen, chlorine, bromine or fluorine atoms or are C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy or carboxamido groups which may be substituted by C.sub.1 -C.sub.6 -alkyl groups; or are phenoxy or C.sub.6 -C.sub.10 -aryl rings onto which further aromatic, aliphatic or heterocyclic rings can be fused, which process comprises hydrolyzing the reaction mixture resulting from cyclization of the respective dianilinoterephthalic acid with polyphosphoric acid or polyphosphate at a temperature of or above 110.degree. C. with water or an aqueous mineral acid solution and then isolating the pigments thus obtained directly; or subjecting the resulting prepigments, if desired after addition of organic solvents, to a finishing treatment and isolating the pigments; or subjecting the resulting coarsely crystalline crude pigments to fine dispersion and then isolating the pigments; or subjecting the prepigments obtained after fine dispersion, if desired after addition of solvents, to a finishing treatment and isolating the pigments.
This gives quinacridone pigments having excellent coloristic and rheological properties.

REFERENCES:
patent: 3160510 (1964-12-01), Ehrich
patent: 3256285 (1966-06-01), Fuchs et al.
patent: 3257405 (1966-06-01), Gerson et al.
patent: 4310359 (1982-01-01), Ehashi et al.
patent: 4455173 (1984-06-01), Jaffe
patent: 5491235 (1996-02-01), Campos et al.
patent: 5591258 (1997-01-01), Urban et al.

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