The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 10, 1989
Filed:
Mar. 20, 1987
Bernhard H Nowakowsky, Ludwigshafen, DE;
Juergen Beck, Mannheim, DE;
Heinrich Hartmann, Limburgerhof, DE;
Christos Vamvakaris, Kallstadt, DE;
BASF Aktiengesellschaft, Ludwigshafen, DE;
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.