Process for the production of thermoplastic molding materials based on vinyl polymers

US4181788A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Frank Wingler · Leverkusen, DE
• Lothar Liebig · Leverkusen, DE
• Gerd Wassmuth · Leverkusen, DE
• Martin Ullrich · Leverkusen, DE
• Manfred Hederich · Leverkusen, DE

Key dates

• Filing date: May 23, 1978
• Grant date: Jan 1, 1980
• Expiry date: May 23, 1998

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B01J2219/00094
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

A process for the production of thermoplastically processible moulding materials based on vinyl polymers of high chemical and molecular uniformity and having residual monomer contents of less than 0.1 mol % which comprises the steps of: PA0 (i) mass homogeneous phase polymerization of at least one vinyl monomer in a stirred continuously charged tank reactor to a conversion of from 25 to 60 mol %; PA0 (ii) directly concentrating the syrup consisting of residual monomers and vinyl polymer dissolved therein obtained from step (i) in a spiral tube evaporator at a temperature of from 60.degree. to 250.degree. C. and at a pressure of 100 m bar to 35 bar to obtain a solid content of vinyl polymer of from 40 to 90 mol %; PA0 (iii) directly charging the concentrate obtained from step (ii) to the inlet zone of a screw evaporator which consists of at least two sequential zones in order to effect further concentration, in which a first zone at a pressure of from 10 to 300 m bar and at a temperature of from 100.degree. to 250.degree. C. concentrates the vinyl polymer to a solid content of from 80 to 99 mol-%, and each subsequent zone at a pressure of 1 to 200 m bar and at a temperature of 150.d…