Method of producing an azo pigment suitable for use in a gravure printing ink and azo pigments produced thereby

摘要

An azo pigment suitable for use in gravure printing ink is produced by treating 100 parts by weight of a starting azo pigment with from 1 to 30 parts by weight of an amine, from 0.1 to 0.5 equivalent of a fatty acid and/or rosin or a derivative thereof, based on the amine, and from 0.5 to 50 parts by weight of a resin containing carboxyl groups and having an acid value of at least 50. The thus-produced azo pigment may be formulated in gravure printing ink, which exhibits improved gloss, flowability and aging discoloration characteristics. Such an ink practically does not penetrate through even when printed on cheap paper or uncoated paper.