Patent ID: 6921801

Claim:
A process for the preparation of a water-soluble acrylic copolymer comprising the following stages: (i) preparation of at least one monomer (1) of formula in which R 1 , R 2 and R 3 are identical to or different from one another and can be a hydrogen atom or a methyl group; Ao is an —O(RtO) m Rz or —NRp(RtO) m Rz group, Rt being a saturated alkylene group having from 1 to 4 carbon atoms, Rz being a saturated alkyl group having from 1 to 6 carbon atoms and Rp being a hydrogen atom or a saturated alkyl group having from 1 to 8 carbon atoms; and m being an integer between 3 and 150; by reaction of an excess of (meth)acrylic anhydride derivative (1′) of formula in which R 1 , R 2 and R 3 are as defined above, with a compound of formula AoH, Ao being as defined above, (ii) copolymerization of said monomer (1) with at least one monomer (2) of (meth)acrylic acid or of a derivative of this acid, with the said excess of derivative (1′) remaining after the reaction between derivative (1′) and the compound AOH, being left during copolymerization stage ii).