Treatment of aqueous systems

Abstract

A method is shown of treating an aqueous system comprising adding to the system a water-soluble tri-copolymer having the formula I: (A).sub.x (B).sub.y (C).sub.z I or a salt thereof, wherein A is a group having the formula: ##STR1## or a hydrolysed (dicarboxylic acid or salt) form of this group; B is a group having the formula: --CH.sub.2 --C(R.sub.1)(CO.sub.2 R.sub.2)-- wherein R.sub.1 is a hydrogen or methyl, and R.sub.2 is hydrogen or C.sub.1 -C.sub.8 straight- or branched chain alkyl, preferably methyl or ether, or R.sub.2 is C.sub.1 -C.sub.8 straight- or branched chain alkyl substituted by a group --OR.sub.3 wherein R.sub.3 is hydrogen or a group of formula --[CH.sub.2 CH(R.sub.4)O].sub.n H wherein R.sub.4 is hydrogen or methyl and n is an integer from 1 to 10; C is a group having the formula: --CH(R.sub.5)--C(R.sub.6)(R.sub.7)-- wherein R.sub.5 is hydrogen, phenyl or C.sub.1 -C.sub.18 straight- or branched chain alkyl, preferably hydrogen and R.sub.6 and R.sub.7, independently, are hydrogen, C.sub.1 -C.sub.18 straight- or branched chain alkyl, phenyl or substituted phenyl, and x, y and z are integers, so chosen that (1) the molar ratio A of in the tri-copolymer ranges from 30 to 80% by weight; the molar ratio of B in the tri-copolymer ranges from 10 to 40% by weight; and the molecular ratio of C ranges from 10 tp 30% by weight; and (2) the molar weight of the tri-copolymer is within the range of from 600 to 10,000.

Dependencies are inferred from the claim text.