National Starch and Chemical Investment Holding Corporation

James H Belcher, Deceased

Allen M Carrier

Anne-Marie B Austin

Michael L Standish

Maleate copolymers comprise less than 1% residual total free monomer and have a weight average molecular weight of 1,000 to 4,000. The copolymer comprises at least 50 mole percent maleate, 10 to 50 mole percent acrylate monomer and 1 to 10 mole percent of at least one non-ionic comonomer. The copolymers are useful in inhibiting deposition of water hardness ions, in detergents and as dispersants in aqueous slurries. Copolymers are prepared by an aqueous solution polymerization process, comprising the steps of initially neutralizing at least 70%, on a molar basis, of the charge of a maleate monomer, followed by the slow addition of at least one polymerizable comonomer, together with an oxidative free radical initiator and a suitable metallic ion reductant, for synthesis over at least a three hour period at 80 to 100.degree. C., followed by the addition of more initiator.

Multifunctional maleate polymers

The water-treatment processes of this invention utilize maleate copolymers to sequester water hardness ions, modify crystal formation in water and inhibit scale formation (e.g., in circulating water systems and oil field production systems), which polymers contain from about 40 to 70 mole percent of dicarboxylic functionality provided by a maleate monomer upon polymerization, from about 1 to about 15 mole percent of the polymerized residue of a non-ionic monomer, and from about 20 to about 50 mole percent of monocarboxylic functionality.

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Chattanooga, TN, United States of America

James H Belcher, Deceased