Seeded emulsion polymerization of .alpha.-methylstyrene and acrylonitrile

US4920178A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Karl Zabrocki · Waldbröl, DE
• Christian Lindner · Bensheim, DE
• Otto Koch · Leichlingen, DE
• Hans-Eberhard Braese · Cologne, DE

Key dates

• Filing date: Feb 21, 1989
• Grant date: Apr 24, 1990
• Expiry date: Feb 21, 2009

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08L51/003
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

An .alpha.-methylstyrene/acrylonitrile copolymer obtainable by emulsion polymerization which, in combination with other polymers, particularly PVC, enables alloys of outstanding thermal stability and color stability to be produced and, in addition, has a high heat distortion temperature and shows good fogging behavior and which is obtained by radically initiated inflow copolymerization of a mixture of 30 to 32 parts by weight acrylonitrile and 68 to 70 parts by weight .alpha.-methylstyrene in the presence of an emulsifier containing carboxyl groups. The polymerization is conducted in such a way that a seed latex of the same copolymer or of an analogous copolymer is introduced before addition of the monomers is commenced, the reaction temperature is kept between 75.degree. and 82.degree. C. and the molar ratio of emulsifier to initiator is between 4 and 6.