Method for producing polymers with a neutral color tone

US8907009B2 · kind B2 · utility

Assignee

• Lurgi Zimmer GmbH · DE

Inventors

• Brigitta Otto · Lenzen (Elbe), DE
• Rainer Linke · Gummersbach, DE
• Oliver Schmidt · Palo Alto, US

Key dates

• Filing date: Aug 28, 2009
• Grant date: Dec 9, 2014
• Expiry date: Sep 6, 2032

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08K5/0041
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

A method is disclosed for producing polymers with a neutral color tone, wherein a blue and red dye are added before entry into the last polyreaction stage, wherein adjustment of a neutral color tone of the polymer, using a total dye concentration in the polymer of no more than 3 ppm and a proportion of the blue dye in the resulting dye mixture of at least 50% by weight, occurs through independent adjustment of a and b color values in the Lab color space by determination of a and b color values of the polymer without addition of dyes, establishment of the total dye concentration depending on the b-value shift to be achieved, establishment of the required mixture ratio of the colors red and blue depending on the a-value shift to be achieved, and metering of the established content of dye mixture into the reaction mixture.