Water treatment polymers and methods of use thereof

Claim 1

A method of inhibiting the corrosion of metal parts in contact with a cooling water system with little or no attendant deposition of scale on said metal parts, which corrosion inhibition is obtained by providing for the formation of a protective passive oxide film on the metal surface in contact with said aqueous medium, which method comprises assuring that the pH of said aqueous medium is 5.5 or above; assuring that the aqueous medium contains a calcium or other appropriate ion concentration selected from the group consisting of zinc, nickel and chromium and mixtures thereof; and adding to said aqueous medium (1) a water soluble polymer comprising repeat unit moieties (a) and (b) wherein said repeat unit (a) comprises the structure ##STR10## and wherein said repeat unit (b) comprises the structure ##STR11## wherein each R 1 is independently H or lower alkyl (C 1 -C 3 ), R 2 is OH or OM, M is a water soluble cation, R 3 is a hydroxy substituted alkylene radical having from 1 to about 6 carbon atoms, X is SO 3 , Z is H or a water soluble cation or cations, and a is 1, the molar ratio x:y of said polymer being between about 30:1 to 1:20; (2) a water soluble orthophosphate compound; and (3) a water soluble polyphosphate compound, said polymer being such that together with the orthophosphate compound is effective to promote the metal oxide film with no attendant deposition, and the amount of (1), (2) and (3) being added being sufficient to provide a substantially scale-free protective passive oxide film on the metallic surface.

Claim 2

A method of inhibiting the corrosion of metal parts in contact with a cooling water system with little or no attendant deposition of scale on said metal parts, which corrosion inhibition is obtained by providing for the formation of a protective passive oxide film on the metal surface in contact with said aqueous medium, which method comprises assuring that the pH of said aqueous medium is 5.5 or above; assuring that the aqueous medium contains a calcium or other appropriate ion concentration selected from the group consisting of zinc, nickel and chromium and mixtures thereof; and adding to said aqueous medium (1) a water soluble polymer comprising repeat unit moieties (a) and (b) wherein said repeat unit (a) comprises the structure ##STR10## and wherein said repeat unit (b) comprises the structure ##STR11## wherein each R 1 is independently H or lower alkyl (C 1 -C 3 ), R 2 is OH or OM, M is a water soluble cation, R 3 is a hydroxy substituted alkylene radical having from 1 to about 6 carbon atoms, X is SO 3 , Z is H or a water soluble cation or cations, and a is 1, the molar ratio x:y of said polymer being between about 30:1 to 1:20; (2) a water soluble orthophosphate compound; and (3) a water soluble polyphosphate compound, said polymer being such that together with the orthophosphate compound is effective to promote the metal oxide film with no attendant deposition, and the amount of (1), (2) and (3) being added being sufficient to provide a substantially scale-free protective passive oxide film on the metallic surface.