Patent ID: 6447696
Filing Date: 2002-09-10
Classification: C08F,C08L,C11D,C23F

Abstract:
A scale inhibitor comprising a grafted polymer, which is a product by a process including the step of graft-polymerizing a graft component (B) onto a polyether compound (A) in a ratio such that the graft component (B) is in the range of 0.1Ëœ1.2 weight parts per 1 weight part of the polyether compound (A), wherein the polyether compound (A) is a product by a process including the step of polymerizing an alkylene oxide component with an ethylene oxide content of at least 50 mol % and has a number-average molecular weight of not lower than 200, and wherein the graft component (B) includes N-vinylpyrrolidone (b1) and a monoethylenically unsaturated monomer (b2) as essential components, wherein the monomer (b2) includes a carboxyl-group-containing monoethylenically unsaturated monomer (b2-1) as an essential component and optionally a cationic monoethylenically unsaturated monomer (b2-2), wherein said carboxy-group-containing monoethylenically unsaturated monomer (b2-1) includes at least one selected from the group consisting of acrylic acid and esters thereof, maleic acid and maleic anhydride where the monomer (b2-1) is optionally a monomer having a structure formable into a carboxylic acid (or its salt) by hydrolysis, wherein when the monomer (b2-1) includes the monomer having the structure formable into a carboxylic acid (or salt) by hydrolysis, not less than 50 mol % of all structural units as derived from the monomer (b2-1) have a carboxyl group, inclusive of a carboxyl group formable by the hydrolysis of the monomer having the above structure, with the proviso that when the carboxylic salt is formed by the hydrolysis, this carboxylic salt is also taken as the carboxyl group.