Composition and method for stripping nickel, zinc and cadmium from substrates of iron and copper

Claim 1

A COMPOSITION FOR SELECTIVELY STRIPPING NICKEL, CADMIUM AND ZINC COATINGS FROM A WORKPIECE PROVIDING A SUBSTRATE SURFACE ON IRON, COPPER OR ALLOYS OF IRON OR COPPER COMPRISING, ON A PER LITER BASIS AT MAKEUP, AN AQUEOUS SOLUTION OF: A. ABOUT 20 TO 80 GRAMS OF A WATER-SOLUBLE NITROBENZIOC ACID COMPOUND SELECTED FROM THE GROUP CONSISTING OF NITROBENZOIC ACID, RING-SUBSTITUTED NITROBENZOIC ACID, THE AMMONIUM AND ALKYLI METAL SALTS THEREOF, AND MIXTURES THEREOF; B. ABOUT 40 TO 160 GRAMS OF A WATER-SOLUBLE CARNOMATE COMPOUND SELECTED FROM THE GROUP CONSISTING OF CARBONIC ACID, THE AMMONIUM AND ALKALI METAL SALTS THEREOF, AND MIXTURES THEREOF; C. ABOUT 0.2 TO 8.0 GRAMS OF A WATER SOLUBLE DITHIOCARBAMATE COMPOUND SELECTED FROM THE GROUP CONSISTING OF SUBSTITUTED AND UNSUBSTITUTED THIOCARBAMIC ACIDS, THE ALKALI METAL AND AMMONIUM SALTS THEREOF, AND MIXTURES THEREOF; D. ABOUT 0.2 TO 16.0 GRAMS OF A WATER-SOLUBLE THIOSULFURIC ACID COMPOUND SELECTED FROM THE GROUP CONSISTING OF THIOSULFURIC ACID, THE ALKALI METAL AND AMMONIUM SALTS THEREOF, AND MIXTURES THEREOF; E. AMMONIUM HYDROXIDE IN A QUANTITY SUFFICIENT TO PROVIDE A SOLUTION PH OF ABOUT 8.5 TO 10.7; SAID COMPOSITION HAVING A WEIGHT OF AMMONIUM ION (NH4+) TO NITROBENZOIC ACID RADICAL (NO2C6H4COO-) OF ABOUT 1.0 - 3.0:1.0, A WEIGHT RATIO OF THIOSULFURIC ACID RADICAL (S2O3=) TO DITHIOCARBAMATE RADICAL (( (C2 H5)2NSCS-)) OF ABOUT 0.2-8.0:1.0 AND A WEIGHT RTIO OF DITHIOCARBAMATE AND THIOSULFURIC ACID RADICALS COMBINED TO NITROBENZOIC ACID RADICAL OF ABOUT 0.01 - 0.70:1.0.

Claim 9

A method for selectively stripping nickel, cadmium and zinc coatings from a workpiece providing a substrate surface of iron, copper or alloys of iron or copper comprising the steps of: A. preparing on a per liter basis at makeup an aqueous bath comPrising about 20 to 80 grams of a water-soluble nitrobenzoic acid compound selected from the group consisting of nitrobenzoic acid, ring-substituted nitrobenzoic acid, the ammonium and alkali metal salts thereof, and mixtures thereof; about 40 to 160 grams of a water-soluble carbonate compound selected from the group consisting of carbonic acid, the ammonium and alkali metal salts thereof, and mixtures thereof; about 0.2 to 8.0 grams of a water-soluble dithiocarbamate compound selected from the group consisting of substituted and unsubstituted thiocarbamic acids, the alkali metal and ammonium salts thereof and mixtures thereof; aboout 0.2 to 16.0 grams of a water-soluble thiosulfuric acid compound selected from the group consisting of thiosulfuric acid, the alkali metal and ammonium salts thereof, and mixtures thereof; and ammonium hydroxide in a quantity sufficient to provide a solution pH of about 8.5 to 10.7; said bath having a weight ratio of ammonium ion (NH4 ) to nitrobenzoic acid radical (NO2C6H4COO ) of about 1.0 - 3.0:1.0, a weight ratio of thiosulfuric acid radical (S2O3 ) to dithiocarbamate radical (( (C2H5)2NSCS ) of about 1.2 - 8.0:1.0 and a weight ratio of dithiocarbamate and thiosulfuric acid radicals combined to nitrobenzoic acid radical of about 0.01 - 0.70:1.0; B. maintaining said bath at a temperature of 20* to 60* C.; C. immersing in said bath a workpiece having a substrate with a surface of a metal selected from the group consisting of iron, copper, copper alloys and iron alloys and a coating on at least a portion of the surface thereof of a metal selected from the group consisting of nickel, zinc and cadmium, for a period of time sufficient to strip said coating from said surface; and D. removing said workpiece from said bath and rinsing the surface thereof.

Claim 10

A method for selectively stripping nickel, cadmium and zinc coatings from a workpiece providing a substrate surface of iron, copper or alloys of iron or copper comprising the steps of: A. preparing on a per liter basis at makeup an aqueous bath comPrising about 20 to 80 grams of a water-soluble nitrobenzoic acid compound selected from the group consisting of nitrobenzoic acid, ring-substituted nitrobenzoic acid, the ammonium and alkali metal salts thereof, and mixtures thereof; about 40 to 160 grams of a water-soluble carbonate compound selected from the group consisting of carbonic acid, the ammonium and alkali metal salts thereof, and mixtures thereof; about 0.2 to 8.0 grams of a water-soluble dithiocarbamate compound selected from the group consisting of substituted and unsubstituted thiocarbamic acids, the alkali metal and ammonium salts thereof and mixtures thereof; aboout 0.2 to 16.0 grams of a water-soluble thiosulfuric acid compound selected from the group consisting of thiosulfuric acid, the alkali metal and ammonium salts thereof, and mixtures thereof; and ammonium hydroxide in a quantity sufficient to provide a solution pH of about 8.5 to 10.7; said bath having a weight ratio of ammonium ion (NH4 ) to nitrobenzoic acid radical (NO2C6H4COO ) of about 1.0 - 3.0:1.0, a weight ratio of thiosulfuric acid radical (S2O3 ) to dithiocarbamate radical (( (C2H5)2NSCS ) of about 1.2 - 8.0:1.0 and a weight ratio of dithiocarbamate and thiosulfuric acid radicals combined to nitrobenzoic acid radical of about 0.01 - 0.70:1.0; B. maintaining said bath at a temperature of 20* to 60* C.; C. immersing in said bath a workpiece having a substrate with a surface of a metal selected from the group consisting of iron, copper, copper alloys and iron alloys and a coating on at least a portion of the surface thereof of a metal selected from the group consisting of nickel, zinc and cadmium, for a period of time sufficient to strip said coating from said surface; and D. removing said workpiece from said bath and rinsing the surface thereof.