Patent ID: 6114294
Filing Date: 2000-09-05
Classification: C02F,C11D

Abstract:
Method of controlling scale in aqueous systems comprising adding to the aqueous system at least one copolymer comprising polymerized units of the following monomers:(I) 50-98% by weight of one or more weak acid;(II) 2-50% by weight of one or more unsaturated sulphonic acid selected from the group consisting of 3-methacrylamido-2-hydroxy-propanesulphonic acid, allylsulphonic acid, methallylsulphonic acid, allyoxybenzenesulphonic acid, methallyoxybenzenesulphonic acid, 2-hydroxy-3-(2-propenyloxy)propanesulphonic acid, 2-methyl-2-propene-1-sulphonic acid, styrene sulphonic acid, and vinylsulphonic acid and water soluble salts thereof;(III) 0-30% by weight of one or more monoethylenically unsaturated C.sub.4 -C.sub.8 dicarboxylic acid; and(IV) 0-30% by weight of one or more monoethylenically unsaturated monomers polymerizable with (I), (II) and (III);wherein the total of monomers (I), (II), (III) and (IV) equals 100% by weight of copolymer; and further wherein the scale being controlled is selected from the group consisting of tripolyphosphate and pyrophosphate.