Method for processing crude polyoxymethylene

US5541284A · kind A · utility

Assignee

• Dequssa AG · DE

Inventors

• Detlef Arnoldi · Weisenheim am Berg, DE
• Udo Gropp · Bad Endorf, DE
• Edwin Nun · Billerbeck, DE

Key dates

• Filing date: Mar 20, 1995
• Grant date: Jul 30, 1996
• Expiry date: Mar 20, 2015

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G2/28
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

The subject invention relates to method for processing crude polyoxymethylene in which the isolation of unstable components from crude polyoxymethylene, such as residual monomers which are at least partly in the form of cyclic formaldehyde derivatives, is effected by treatment of the crude polyoxymethylene with an inert gaseous medium. The method of the invention is characterized in that the gaseous medium contains at least 10 volume % of water vapor, and less than 0.1 volume % of a volatile base, and/or less than 1 volume % of a volatile solvent. In an alternative variant method, the gaseous medium contains at least 10 volume % of water vapor and the treatment occurs at a temperature between 114.degree. C and the softening temperature of the crude polyoxymethylene and at a pressure of less 1.2 .multidot.10.sup.5 Pa.