Thermochromic effect pigment and process for producing the same

US5690857A · kind A · utility

Assignee

• Merck Patent GmbH · DE

Inventors

• Karl Osterried · Dieburg, DE
• Magarete Herbski · Ober-Ramstadt, DE
• Ian C. Sage · Broadstone, GB

Key dates

• Filing date: Jun 7, 1994
• Grant date: Nov 25, 1997
• Expiry date: Jun 7, 2014

Classification

• Technology area (CPC A): Human Necessities
• CPC primary: A61K2800/438
• WIPO field: Pharmaceuticals
• WIPO sector: Chemistry

Abstract

A thermochromic effect pigment comprising a thermochromic liquid crystal material encapsulated with a polymer and coated with one or more inorganic metal oxides or nearly insoluble metal salts selected from Al.sub.2 O.sub.3, SnO.sub.2, ZrO.sub.2, TiO.sub.2, CaO, SiO.sub.2, ZnO, MgO or BaSO.sub.4. The pigment is stable in solvent-based formulations and can be used as a colorant in the form of an aqueous suspension or as a powder in lacquer compositions, plastic compositions, dyed filter compositions, dyed glass compositions, dyed cosmetic compositions, printing ink compositions, and in hair coloring agents.