Batchwise preparation of crosslinked, finely divided polymers

US4873299A · 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: Mar 20, 1987
• Grant date: Oct 10, 1989
• Expiry date: Mar 20, 2007

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08F2/10
• WIPO field: Medical technology
• WIPO sector: Instruments

Abstract

Crosslinked, finely divided, water-absorbing polymers are prepared in a batchwise process by copolymerization of 100 parts by weight of a monomer mixture of acrylic acid or methacrylic acid, each of which is neutralized with from 0 to 100 mol% of an alkali metal or ammonium base,or acrylamide, methacrylamide or N-vinylpyrrolidone with, as a crosslinking agent, from 0.01 to 5 parts by weight of a monomer containing two or more ethylenically unsaturated double bonds in 20-80% by weight aqueous solution in the presence of an initiator in a multistage procedure in a batchwise mixing apparatus wih constant thorough mixing in all stages, in the first stage the aqueous monomer solution being copolymerized at from 45.degree. to 95.degree. C. and under from 0.1 to 0.8 bar with removal of some of the water by distillation, in the second stage the copolymerization being completed at from 100.degree. to 170.degree. C. under a pressure of up to 8 bar, and in the third stage the water content of the resulting finely divided copolymer being decreased to 0.5-10% by weight under reduced pressure.