Use of phosphino polymer and polyhydroxypolycarboxylic acid as corrosion inhibitor

1. A method of inhibiting corrosion in a cooling water system comprising adding to the water system a corrosive inhibiting effective amount of a corrosion inhibitor system free of zinc salts, zinc oxides and zinc sulfates, the corrosion inhibitor system consisting essentially of:

(a) a polycarboxylic acid selected from the group consisting of polyhydroxydicarboxylic acids, polyhydroxytricarboxylic acids or a mixture thereof; and

(b) a water soluble phosphino polymer either (i) derived from a phosphinyl unsaturated monomer and an ethylenically unsaturated carboxylic acid or ester; or (ii) a polycarboxylic acid or polycarboxylate having at least one pendant phosphino group or a phosphino group within the backbone of the polymer.

2. The method of claim 1 , wherein the water soluble phosphino polymer is a polycarboxylic acid having at least one phosphino group pendant to the polycarboxylic acid.

3. The method of claim 1 , wherein at least one of the following prevails:

(a) the weight average molecular weight of the water soluble phosphino polymer is from about 500 to about 10,000; or

(b) the amount of phosphorus in the aqueous water system contributed by the phosphino polymer is less than about 1.5 ppm.

4. The method of claim 1 , wherein the polyhydroxypolycarboxylic acid is selected from the group consisting of saccharic acid, citric acid, tartaric acid, mucic acid, gluconic acid and combinations thereof.

5. The method of claim 1 , wherein the cooling water system is a closed cooling water system, open circulating cooling water system, an air-conditioning water system, a wastewater treatment system, or a deionized water production system.

6. The method of claim 1 , wherein the water soluble phosphino polymer is derived from a phosphinyl unsaturated monomer and an ethylenically unsaturated carboxylic acid or ester.

7. The method of claim 6 , wherein the ethylenically unsaturated carboxylic acid or ester is selected from the group consisting of acrylic acid, methacrylic acid, lactic acid, maleic acid, maleic anhydride or a dicarboxylic acid of itaconic acid, fumaric acid, mesoconic acid, citraconic acid or tartaric acid or a monoester of the dicarboxylic acid with C 1 -C 8 alkanol, and mixtures thereof.

8. The method of claim 7 , wherein the phosphino polymer further comprises styrene, a C 1 -C 6 olefin, vinyl acetate, vinyl chloride, vinyl alcohol, a C 1 -C 6 alkyl acrylate, vinyl pyridine, vinyl pyrrolidone, acrylamide, an acrylamide derivative, a vinyl sulfonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) or vinyl phosphonic acid.

9. The method of claim 6 , wherein the phosphinyl unsaturated monomer is a phosphinyl acrylate or phosphinyl methacrylate.

10. The method of claim 9 , wherein the phosphinyl acrylate or phosphinyl methacrylate is selected from the group consisting of (hydroxy)phosphinyl-C 1 -C 4 -alkyl (meth)acrylates and (dihydroxy)phosphinyl-C 1 -C 4 alkyl (meth)acrylates.

11. The method of claim 6 , wherein about 1 to about 8 weight percent of the polymer contains the phosphinyl unsaturated monomer.

12. A method of inhibiting the deposition of scales in a cooling water system comprising adding to the water system a scale inhibiting effective amount of a corrosion inhibitor system composed of only organic components, the corrosion inhibitor system consisting essentially of:

(a) a polyhydroxypolycarboxylic acid selected from the group consisting of polyhydroxydicarboxylic acids, polyhydroxytricarboxylic acids or a mixture thereof; and

(b) a water soluble phosphino polycarboxylate.

13. The method of claim 12 , wherein either:

(a) the polyhydroxypolycarboxylic acid is added to the cooling water system prior to the addition of the water soluble phosphino polycarboxylate;

(b) the water soluble phosphino polycarboxylate is added to the cooling water system prior to the polyhydroxypolycarboxylic acid; or

(c) the polyhydroxypolycarboxylic acid and the water soluble phosphino polycarboxylate are added to the cooling water system at the same time.

14. The method of claim 12 , wherein the cooling water system is a closed cooling water system, open circulating cooling water system, an air-conditioning water system, a wastewater treatment system, or a deionized water production system.

15. The method of claim 12 , wherein the cooling water system contains at least one component selected from the group consisting of a scale inhibitor, a biocide, a chlorine-containing component, a taggant, a yellow metal corrosion inhibitor, and combinations thereof.

16. The method of claim 12 , wherein the pH of fluid in the cooling water system is between from about 6.5 to about 9.5.

17. A method of inhibiting corrosion in a cooling water system comprising adding to the water system a corrosive inhibiting effective amount of a corrosion inhibitor system consisting essentially of:

(a) a polyhydroxypolycarboxylic acid selected from the group consisting of polyhydroxydicarboxylic acids, polyhydroxytricarboxylic acids or a mixture thereof; and

(b) a water soluble phosphino polymer.

18. The method of claim 17 , wherein at least one of the following conditions prevail:

(a) the water soluble phosphino polymer is derived from a phosphinyl unsaturated monomer and an ethylenically unsaturated carboxylic acid or ester;

(b) the water soluble phosphino polymer is a polycarboxylic acid having at least one phosphino group pendant to the polycarboxylic acid;

(c) the phosphino polymer is a homopolymer or copolymer of an ethylenically unsaturated acid monomer having a phosphino group within the backbone of the polymer;

(d) the weight average molecular weight of the water soluble phosphino polymer is from about 500 to about 10,000;

(e) the amount of phosphorus in the aqueous water system contributed by the phosphino polymer is less than about 1.5 ppm;

(f) the polyhydroxypolycarboxylic acid is selected from the group consisting of saccharic acid, citric acid, tartaric acid, mucic acid, gluconic acid and combinations thereof; or

(g) the cooling water system is a closed cooling water system, open circulating cooling water system, an air-conditioning water system, a wastewater treatment system, or a deionized water production system.