Process for preparing new crystal polymorphs of a methyl-substituted benzimidazolone-dioxazine pigment

US6620931B2 · kind B2 · utility

Assignee

• Clariant Corporation · DE

Inventors

• Martin Schmidt · Frankfurt am Main, DE
• Peter Kempter · Bad Soden, DE
• Roland Born · Wiesmoor, DE

Key dates

• Filing date: Oct 22, 2001
• Grant date: Sep 16, 2003
• Expiry date: Oct 22, 2021

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C09B19/02
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Process for phase conversion of a methyl-substituted, benzimidazolone-fused dioxazine pigment of composition C22H12Cl2N6O4 having the formula (1) or of an isomer or tautomer thereof, which comprises treating the pigment of formula (1) with certain organic solvents.In the course of this phase conversion, 4 novel crystal polymorphs are formed which are called phases II, IV, V and VI and are characterized by means of their X-ray powder diagrams.The novel polymorphs are of low solubility and feature good fastness properties and violet colorations.The novel crystal polymorphs are suitable for pigmenting coating materials, plastics, printing inks, aqueous or solvent-based pigment preparations, electrophotographic toners and developers, powder coating materials, inks, preferably inkjet inks, and color filters, and for coloring seed.