Patent ID: 6900275

Claim:
A process for producing a (meth)acrylic acid (salt) polymer, which comprises the step of carrying out polymerization of an unsaturated monocarboxylic monomer (a) of a general formula (1) below and an unsaturated polyalkylene glycolic monomer (b) of a general formula (2) below with a polymerization initiator, with the process using a redox polymerization initiator including hydrogen peroxide as the polymerization initiator and L-ascorbic acid as a reducing agent, and wherein the amount of the hydrogen peroxide as used is in the range of 0.5 to 10 mol.% relative to the total of the monomers, wherein the general formula (1) is: where: R 1 denotes a hydrogen atom or a methyl group; and M denotes a hydrogen atom, a monovalent metal, a divalent metal, an ammonium group, or an organic amine group; and wherein the general formula (2) is: where: R 1 denotes hydrogen or a methyl group; R 2 denotes —COO(R 3 O) m R 4 wherein R 3 O denotes at least one kind of oxyalkylene group having 2 to 18 carbon atoms and, in the case of at least two kinds, their form of addition may be either block addition or random addition, and wherein R 4 denotes hydrogen or an alkyl group having 1 to 22 carbon atoms; and m is a molar-number-average degree of addition polymerization of the oxyalkylene group and denotes an integer of 1 to 300.