| abstract |
A crystal growth inhibitor for azo pigments is disclosed. The crystal growth inhibitor comprises: (1) one or more sulfonated or carboxylated amines, and (2) one or more coupling components selected from the group consisting of acetoacetanilides, naphthanilides, pyrazalones and benzamidazoles; the coupling component being bonded to the sulfonated or carboxylated amines. The crystal growth inhibitor can be produced separately and added to the coupling component prior to the coupling reaction, or it can be formed in situ with the pigment. Preferably, an improved pigment according to the invention includes 2% to 5% by weight of the crystal growth inhibitor. Monoazo pigments including the crystal growth inhibitor have been shown to have greatly improved gloss, transparency and tinctorial strength. |