Patent ID: 8916678

Claim:
A polyalkylene glycol polymer having a monomer unit derived from a polyalkylene glycol monomer and monomer unit derived from a monoethylenically unsaturated carboxylic acid (salt) and/or a monoethylenically unsaturated sulfonic acid (salt) monomer, wherein the polyalkylene glycol polymer is a polyalkylene glycol polymer having a carboxylic acid (salt) group and/or a sulfonic acid (salt) group, and having a weight average molecular weight of 500 to 100,000 and the polyalkylene glycol polymer contains at least 10% by weight of a carboxylic acid (salt) and/or sulfonic acid (salt) monomer unit and 10 to 90% by weight of the polyalkylene glycol monomer unit relative to 100% by weight of the polyalkylene glycol polymer, wherein the carboxylic acid (salt) and/or the sulfonic acid (salt) monomer unit is derived from a monoethylenically unsaturated carboxylic acid (salt)) and/or monoethylenically unsaturated sulfonic acid (salt) and wherein the polyalkylene glycol monomer consists of 1) a polyalkylene glycol backbone, 2) a polymerizable double bond provided by a residue from isoprenol, allyl alcohol, or methallyl alcohol, wherein said residue is bound to a terminal oxygen of said polyalkylene glycol backbone; and 3) a residue provided by a glycidyl ether containing 3 to 25 carbon atoms, wherein said residue is bound to a terminal oxygen of said polyalkylene glycol backbone, and said residue contains a hydrocarbon group containing 1 to 20 carbon atoms at the end of said residue, and said hydrocarbon group containing 1 to 20 carbon atoms is at least one member selected from the group consisting of alkyl, aryl, alkylaryl and polycyclic alkyl groups containing 1 to 20 carbon atoms, wherein said residue provided by the glycidyl ether containing 3 to 25 carbon atoms has a hydroxyl group and is formed by a reaction between an epoxy group of the glycidyl ether and a hydroxyl group at the terminal of said polyalkylene glycol backbone.