Crystal polymorphs of C.I. Pigment Yellow 191 and their preparation

US6602342B2 · kind B2 · utility

Assignee

• Clariant Corporation · DE

Inventors

• Martin Schmidt · Frankfurt am Main, DE
• Arpad Acs · Schwalbach, DE
• Rudiger Jung · Kelkheim, DE
• Franz Schui · Frankfurt am Main, DE

Key dates

• Filing date: Jul 2, 2001
• Grant date: Aug 5, 2003
• Expiry date: Aug 2, 2021

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09B67/0029
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

C.I. Pigment Yellow 191 is obtained in new crystal polymorphs (beta, gamma, delta and epsilon phases) if the known alpha phase or another inventive phase of this pigment is treated with certain solvents and reprecipitated.