Process for reducing content of free vinyl chloride by posttreating copolymer with redox catalyst

US4205161A · kind A · utility

Assignee

• Wacker Chemie AG · DE

Inventors

• Hubert Wiest · Burghausen, DE
• Peter Ludwig
• Klaus Hafener · Burghausen, DE
• Erwin Lieb

Key dates

• Filing date: Dec 7, 1977
• Grant date: May 27, 1980
• Expiry date: Dec 7, 1997

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08F214/06
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

A process for the manufacture of vinyl chloride copolymers having a reduced content of free vinyl chloride comprising polymerizing a monomer mixture containing from 15% to 90% by weight of vinyl chloride under aqueous emulsion polymerization conditions with conventional post-polymerization, releasing the pressure, flushing the gas space above the copolymer dispersion free of monomer, cooling the copolymer dispersion to a temperature of from 10.degree. to 40.degree. C., adding a redox catalyst to the cooled dispersion consisting of from 0.002% to 0.5% by weight of the dispersion of an oil-soluble peroxy compound, and a water-soluble sulfur-containing reducing agent in a ratio of reducing agent to peroxy compound of 0.5 to 3 equivalents, allowing the dispersion to stand at a temperature of from 10.degree. to 40.degree. C. for a period of two hours to two days and recovering a copolymer dispersion having a vinyl chloride content of less than 50 ppm.