Patent ID: 7285611

Claim:
A method for the production of an unsaturated polyalkylene glycol copolymer by the copolymerization of a (meth)acrylic acid monomer A and a compound B formed by adding 1-300 mol of an alkylene oxide to 1 mol of an unsaturated alcohol, wherein the combination of one or more species respectively of a persulfate and a bisulfite is used as an initiator, and the polymerization temperature is defined as in the range of 50° C. to 95° C., herein the copolymer possesses sulfur oxygen acid at the terminal thereof, and the value S representing the quantity of sulfur element introduced, which is defined by the formula, S=(quantity of S contained in the copolymer)/(total quantity of S)×100, is not less than 3 wherein the polymer possesses sulfur oxygen acid at the terminal thereof, and the value S representing the quantity of the sulfur element introduced which is defined by the formula, S=(quantity of S contained in the polymer)/(total quantity of S)×100, is not less than 3.