Azo pigment composition having improved process heat stability and dried ink transparency

Abstract From the Canadian patent

Diaryl pigments having excellent dried ink transparency and improved process heat stability are prepared by carrying out the coupling of a bisdiazotized substituted 4,4 diaminobiphenyl with acetoacetanilides and/or pyrazolinones in the presence of an added quantity of one or more substituted aromatic amines containing at last one sulfonic or carboxylic acid substituent, or their salts. The pigments exhibit improved tolerance to variations in drying temperatures and to high drying temperatures, and have improved transparency when present in dried ink formulations.