Patent ID: 6395185
Filing Date: 2002-05-28
Classification: C02F,C11D

Abstract:
Method of controlling poly(phosphate) 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 acids selected from the group consisting of monoethylenically unsaturated C3 to C6 monocarboxylic acid; (II) 2-50% by weight of one or more unsaturated sulfonic acid selected from the group consisting of 2-acrylamido-2-methyl-1-propanesulfonic acid, 2-methacrylamido-2-methyl-1-propane-sulfonic acid, and water soluble salts thereof; (III) 0-30% by weight of one or more monoethylenically unsaturated C4-C8 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; wherein the aqueous system contains sodium tripolyphosphate in an amount not to exceed 1500 parts per million; and further wherein the scale being controlled is selected from the group consisting of tripolyphosphate and pyrophosphate.