Method of preventing corrosion of uncoated aluminum sheet or beverage cans in a brewery pasteurizer water system

Claim 1

A method of preventing dome staining of aluminum beverage cans by pasteurizing said cans at temperatures from 70°-190° F. with aqueous solutions having a pH rangng from about 5.0 to 8.5 and containing: (a) at least 1 ppm, as zinc, of a water soluble zinc salt; (b) at least 1 ppm, as PO -3 of an orthophosphate ion source; and (c) at least 1 ppm of a zinc ion stabilizing polymer having a molecular weight ranging from 1000-50,000 and chosen from the group consisting of: (i) homopolymers and copolymers of acrylic acid, methacrylic acid, their water soluble salts, and mixtures thereof; (ii) copolymers and terpolymers of acrylic acid, methacrylic acid, their water soluble salts and vinylic monomers chosen from (meth)acrylamide and N-alkylated (meth)acrylamide chosen from the group N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, and N-t-butyl (meth)acrylamide; and (iii) terpolymers of (meth)acrylic acid, (meth)acrylamide, and an N-substituted (meth)acrylamide represented by the formula: ##STR5## wherein R 1 is a hydrocarbon bridging group having from 1-12 carbon atoms and which may be linear or branched alkyl, aryl, alkaryl, arylalkyl, and mixtures thereof; X is from the group --SO 3 M, --NR 2 , --NR 3 Y, --O--CH 2 CHRO) m R, and mixtures thereof; n is from 1-6; m is from 0-30; M is, at each occurrence, chosen from H, Na, K, NH 4 , and mixtures thereof; Y is Cl, Br, CH 3 SO 4 , and mixtures thereof; and R is, at each occurrence, chosen independently from H, CH 3 , and C 2 H 5 .

Claim 2

A method of preventing dome staining of aluminum beverage cans by pasteurizing said cans at temperatures from 70°-190° F. with aqueous solutions having a pH rangng from about 5.0 to 8.5 and containing: (a) at least 1 ppm, as zinc, of a water soluble zinc salt; (b) at least 1 ppm, as PO -3 of an orthophosphate ion source; and (c) at least 1 ppm of a zinc ion stabilizing polymer having a molecular weight ranging from 1000-50,000 and chosen from the group consisting of: (i) homopolymers and copolymers of acrylic acid, methacrylic acid, their water soluble salts, and mixtures thereof; (ii) copolymers and terpolymers of acrylic acid, methacrylic acid, their water soluble salts and vinylic monomers chosen from (meth)acrylamide and N-alkylated (meth)acrylamide chosen from the group N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, and N-t-butyl (meth)acrylamide; and (iii) terpolymers of (meth)acrylic acid, (meth)acrylamide, and an N-substituted (meth)acrylamide represented by the formula: ##STR5## wherein R 1 is a hydrocarbon bridging group having from 1-12 carbon atoms and which may be linear or branched alkyl, aryl, alkaryl, arylalkyl, and mixtures thereof; X is from the group --SO 3 M, --NR 2 , --NR 3 Y, --O--CH 2 CHRO) m R, and mixtures thereof; n is from 1-6; m is from 0-30; M is, at each occurrence, chosen from H, Na, K, NH 4 , and mixtures thereof; Y is Cl, Br, CH 3 SO 4 , and mixtures thereof; and R is, at each occurrence, chosen independently from H, CH 3 , and C 2 H 5 .

Claim 4

A method of preventing dome staining of aluminum beverage cans by pasteurizing said cans at a temperature of from 75°-165° F. with aqueous solutions having a pH ranging from about 5.0 to 8.5 and containing: (a) from 2-100 ppm, as zinc, of a water soluble zinc salt; (b) from 3-200 ppm, as PO 4 -3 , of a water soluble orthophosphate source; (c) from 2-200 ppm of a water soluble zinc stabilizing polymer having a molecular weight of from 2500-25,000 and containing at least 25 weight percent (meth)acrylic acid and at least 10 weight percent of a vinylic monomer, or mixtures of vinylic monomers, chosen from the group consisting of: (i) acrylamide and methacrylamide; (ii) N-alkylated acrylamide and N-alkylated methacrylamide chosen from the group consisting of N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, and N-tertiary butyl (meth)acrylamide; (iii) N-substituted (meth)acrylamides represented by: ##STR6## wherein: R 1 is a hydrocarbon bridging group containing 1-12 carbon atoms and being linear or branched alkyl; X is --SO 3 M, --O--CH 2 CHRO) m R, and mixtures thereof; n is from 1-4; m is from 0-20; and M is, at each occurrence, chosen from H, Na, K, NR 4 , and mixtures thereof; and R is, at each occurrence, chosen individually from the group H, --CH 3 , and C 2 H 5 .

Claim 5

A method of preventing dome staining of aluminum beverage cans by pasteurizing said cans at a temperature of from 75°-165° F. with aqueous solutions having a pH ranging from about 5.0 to 8.5 and containing: (a) from 2-100 ppm, as zinc, of a water soluble zinc salt; (b) from 3-200 ppm, as PO 4 -3 , of a water soluble orthophosphate source; (c) from 2-200 ppm of a water soluble zinc stabilizing polymer having a molecular weight of from 2500-25,000 and containing at least 25 weight percent (meth)acrylic acid and at least 10 weight percent of a vinylic monomer, or mixtures of vinylic monomers, chosen from the group consisting of: (i) acrylamide and methacrylamide; (ii) N-alkylated acrylamide and N-alkylated methacrylamide chosen from the group consisting of N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, and N-tertiary butyl (meth)acrylamide; (iii) N-substituted (meth)acrylamides represented by: ##STR6## wherein: R 1 is a hydrocarbon bridging group containing 1-12 carbon atoms and being linear or branched alkyl; X is --SO 3 M, --O--CH 2 CHRO) m R, and mixtures thereof; n is from 1-4; m is from 0-20; and M is, at each occurrence, chosen from H, Na, K, NR 4 , and mixtures thereof; and R is, at each occurrence, chosen individually from the group H, --CH 3 , and C 2 H 5 .