Multifunctional calcium carbonate and calcium phosphate scale inhibitor
AssigneeNational Starch and Chemical Investment Holding Corporation
InventorsAnne-Marie B. Austin, Eric C. Ward
Life of this patent
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Abstract
The present invention is directed a multifunctional polymer capable of inhibiting both calcium carbonate and calcium phosphate scale. The multifunctional polymer contains at least one monomer unit from each of four groups: dicarboxylic acids, mono-carboxylic acids, nonionic monomers, and sulfonated or sulfated monomers. The polymer also inhibits many other alkaline earth scales, such as calcium sulfate scale and provides stabilization of minerals such as iron, zinc and manganese. The polymer is especially effective in highly stressed systems that contain high electrolyte concentrations and have a high number of cycles of concentration.
Claims6
A process for inhibiting calcium carbonate and calcium phosphate scale formation comprising adding to an aqueous system an effective amount of a polymer comprising a multifunctional polymer composition formed from a monomer mixture comprising:
- at least one dicarboxylic acid present in an amount of 15 to 40 mole percent, wherein the dicarboxylic acid monomer is 10 to 95 percent neutralized;
- at least one monocarboxylic acid present in an amount of 37 to 79 mole percent;
- at least one non-ionic monomer present in an amount of 1 to 8 mole percent,
- wherein the at least one non-ionic monomer is selected from the group consisting of C1-C6 alkyl esters of (meth)acrylic acid and the alkali or alkaline earth metal or ammonium salts thereof, acrylamide and the C1-C6 alkyl-substituted acrylamides, the N-alkyl substituted acrylamides, the N-alkanol-substituted acrylamides and combinations thereof;
- and
- at least one sulfonated or sulfated monomer present in an amount of 5 to 15 mole percent;
- wherein the polymer composition has a weight average molecular weight of from 2,500 to 6,000, and
- wherein the polymer composition inhibits calcium scale formation in an aqueous system having a Langelier Saturation Index greater than 2.0.
Dependencies are inferred from the claim text.