Continuous preparation of finely divided gel-like crosslinked polymers

US4769427A · kind A · utility

Assignee

• BASF SE

Inventors

• Bernhard H. Nowakowsky · Ludwigshafen, DE
• Juergen Beck · Mannheim, DE
• Heinrich Hartmann · Schifferstadt, DE
• Christos Vamvakaris · Kallstadt, DE

Key dates

• Filing date: Oct 22, 1986
• Grant date: Sep 6, 1988
• Expiry date: Oct 22, 2006

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S526/92
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

Finely divided, gel-like crosslinked polymers are prepared by a continuous method in which a monomer mixture which contains, per 100 parts by weight of acrylic acid or methacrylic acid, from 50 to 100 mol % of which in each case are neutralized, acrylamide, methacrylamide or N-vinylpyrrolidone, from 0 to 30 parts by weight of other water-soluble monoethylenically unsaturated monomers and from 0 to 20 parts by weight of water-insoluble monoethylenically unsaturated monomers is copolymerized with from 0.01 to 5 parts by weight of a crosslinking agent, in 20-65% strength by weight aqueous solution in the presence of an initiator at from 45.degree. to 95.degree. C. in a single-screw cylindrical mixer whose stirrer shaft possesses disk segments which have, at the outer end, mixing bars which are arranged in a manner such that the substances fed in at the entrance of the mixer are conveyed in the axial direction to the exit of the mixer, the aqueous monomer solution in the mixer is polymerized under from 100 to 800 mbar, and some of the water is removed during the polymerization, so that a crumb-like gel having a solids content of from 30 to 70% by weight is discharged.