Ciba Specialty Chemicals Corporation

Basf Se Corporation

Gordian Schilling

Yingxia He

Colin Dennis Campbell

Rhonda Carter

Kevin Rodney Gerzevske

James Will

Melissa Wagner

The invention is directed to a method or use of 2,9-dichloro-quinacridone as an alpha crystal phase inhibitor and optionally, 4,11-dichloroquinacridone during the beta-quinacridone or gamma-quinacridone crude pigment particle size reduction processes. The invention is also directed to solid solutions of quinacridone comprising about 98 to about 80 weight % gamma or beta-quinacridone, about 0.1 to about 10 weight % 2,9-dichloroquinacridone and about 0.1 to about 10 weight % 4,11-dichloroquinacridone.

2,9-dichloro-quinacridone as &#x3b1;-quinacridone crystal phase inhibitor

The invention is directed to a method or use of 2,9-dichloro-quinacridone as a crystal phase inhibitor during the beta-quinacridone or gamma-quinacridone crude pigment particle size reduction processes. 2,9-dichloroquinacridone is added to the milling composition of the crude gamma or crude beta quinacridone.

2,9-Dichloro-quinacridone as alpha-quinacridone crystal phase inhibitor

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Klettgau, Germany

Gordian Schilling