US 5,683,502 AGranted

Incorporation of aromatic polycyclic compounds in quinacridone processes

AssigneeBayer Aktiengesellschaft

InventorsIbraheem T. Badejo, Daphne J. Rice

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Abstract

This invention relates to a process for the preparation of quinacridone pigments by (a) heating, at a temperature of about 80.degree. C. to about 145.degree. C., a reaction mixture containing (i) 2,5-dianilinoterephthalic acid, a 2,5-dianilino-3,6-dihydroterephthalic acid ester, and/or a derivative thereof, (ii) about 3 to about 15 parts by weight, per part of component (a)(i), of a dehydrating agent, and (iii) about 0.1 to about 15 percent by weight, based on component (a)(i), of one or more non-pigmentary aromatic polycyclic compounds and/or derivatives thereof, with the proviso that if component (a)(i) is a 2,5-dianilino-3,6-dihydroterephthalic acid ester or a derivative thereof, reaction step (a) additionally comprises an oxidation step; (b) drowning the reaction mixture from step (a) by adding said reaction mixture to about 3 to about 15 parts by weight, per part of component (a)(i), of a liquid in which the quinacridone pigment is substantially insoluble; (c) isolating the quinacridone pigment; (d) optionally, conditioning the quinacridone pigment; and (e) optionally, blending the resultant pigment with one or more quinacridone derivatives.

Claims15

Dependent claims

A process for the preparation of quinacridone pigments comprising

(a) heating, at a temperature of 80.degree. C. to 145.degree. C., a reaction mixture comprising
(i) 2,5-dianilinoterephthalic acid, a 2,5-dianilino-3,6-dihydroterephthalic acid ester, a derivative of 2,5-dianilinoterephthalic acid or a 2,5-dianilino-3,6-dihydroterephthalic acid ester having one or more substituents in at least one aniline ring, or a mixture thereof,
(ii) 3 to 15 parts by weight, per part of component (a)(i), of a dehydrating agent, and
(iii) 0.1 to 15 percent by weight, based on component (a)(i), of one or more non-pigmentary aromatic polycyclic compounds and/or derivatives thereof,
with the proviso that if component (a)(i) is a 2,5-dianilino-3,6-dihydroterephthalic acid ester or a derivative thereof, reaction step (a) additionally comprises an oxidation step;
(b) drowning the reaction mixture from step (a) by adding said reaction mixture to 3 to 15 parts by weight, per part of component (a)(i), of a liquid in which the quinacridone pigment is substantially insoluble;
(c) isolating the quinacridone pigment;
(d) optionally, conditioning the quinacridone pigment;
and
(e) optionally, blending the quinacridone pigment with one or more quinacridone derivatives.

7 more elements

Dependencies are inferred from the claim text.