Patent ID: 9476127
Filing Date: 2016-10-25
CPC Classification: C02F,C08F,C23F

Claim Text:
1. A method for treating a cooling water system, comprising: adding, in a cooling water system of calcium hardness of 250 mg/L or less as CaCO wherein the (meth)acrylic acid-based copolymer comprises a first structural unit derived from a (meth)acrylic acid-based monomer represented by formula (1) and a second structural unit derived from a (meth)allyl ether-based monomer represented by formula (2), a content of the second structural unit is 1 to 15 mol % relative to 100 mol % of structural units derived from all the monomers, a weight average molecular weight of the (meth)acrylic acid-based copolymer is 7,000 to 28,000, and at least one of main chain terminals of the (meth)acrylic acid-based copolymer is a sulfonic acid group or a salt thereof: where R X represents a hydrogen atom, a metal atom, an ammonium group, or an organic amine group; and where R Y and Z each independently represent a hydroxyl group, or a sulfonic acid group or a salt thereof; and at least one of Y and Z represents a sulfonic acid group or a salt thereof.