Crosslinked polyacrylic acids having low solvent residue, a process for the preparation therof and the use thereof as thickening agents.

摘要

A crosslinked acrylic acid polymer or crosslinked acrylic acid copolymer consisting of at least 80% of acrylic acid and containing less than 5 ppm of methylene chloride obtained by a process comprising the radicalic polymerisation of monomers in a solvent mixture consisting of a mixture of methylene chloride and a carboxylic ester having formula R-COO-R1 wherein R is hydrogen, methyl or ethyl group, R1 is C1-C3 alkyl group, wherein said solvent mixture consists of 60-75% v/v of methylene chloride and 40-25% v/v of carboxylic ester, or, alternatively, dimethyl or diethylcarbonate is used instead of the carboxylic ester, together with a crosslinking agent, in an amount from 0.3 and 4% w/w, calculated on the monomer, and an appropriate free radical initiator as catalyst at a temperature ranging from 35 DEG C and reflux temperature.