Patent ID: 6987186
Filing Date: 2006-01-17
Classification: C09B,Y10T

Abstract:
1. A process for the synthesis of a small particle size quinacridone of beta crystal phase according to formula comprising oxidizing a corresponding dihydroquinacridone according to formula (I) or a salt thereof, in which X and Y, independently of one another, are halogen, —OH, —NO 2 , —CF 3 , an C 1 –C 4 alkyl group, a substituted C 1 –C 4 alkyl group, a C 1 –C 4 alkoxy group, a substituted C 1 –C 4 alkoxy group, a phenyl group, a cyclohexyl group, a phenoxy group, —COOH, a —COO—C 1 –C 4 alkyl group, —SO 3 H, a phenylamino group, a benzamino group, —N(CH 3 ) 2 , —SO 2 NH 2 , —SO 2 N(CH 3 ) 2 , a pyridino group, —CONH 2 or —CON(CH 3 ) 2 , and n is 0, 1, or 2, wherein an additive is present during the oxidation reaction according to formula wherein M is hydrogen, a quaternary nitrogen cation or a metal cation, x is 0 to 2, y is 0.05 to 4, and Q is a substituted quinacridone residue.