Process for producing polymethylmethacrylate molding materials with a neutral color

US6765046B1 · kind B1 · utility

Assignee

• ROEHM GMBH & CO. KG · DE

Inventors

• Uwe Numrich · Weiterstadt, DE
• Michael Wicker · Seeheim-Jugenheim, DE
• Klaus Albrecht · Mainz, DE
• Heinz Vetter · Weiterstadt, DE
• Hermann Jaksch · Ober-Ramstadt, DE
• Ernst Mohr · Murten, CH

Key dates

• Filing date: Sep 3, 1999
• Grant date: Jul 20, 2004
• Expiry date: Sep 3, 2019

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08K5/09
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

Products based on polymethylmethacrylate (PMMA) so resistant to yellowing and so highly transparent that even the edges of plates produced from this material have a neutral colour, i.e. do not display any yellow tone. This effect is obtained by the admixture of 5 to 50 ppm inorganic, reducing phosphorus compounds after polymerisation. This enables the brightener content to be reduced under 10 ppb, and so the end product may also be used in contact with foodstuffs.