Coating solutions for zinc surfaces
AssigneeAmchem Products, Inc.
InventorEarl R. Reinhold
Life of this patent
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Abstract
Solutions and processes for accelerating the rate of application of a conversion coating to zinc surfaces utilizing an aqueous solution containing an oxidizing agent which is a bromate, nitrite, persulfate or hypochlorite; a cation of cobalt, nickel, iron or tin; a complexing agent to keep the cation in solution; and sufficient alkaline material to produce a pH of at least 10.5.
Claims32
An aqueous solution for applying a conversion coating to a zinc or zinc alloy surface consisting essentially of:
- (a) a coating accelerating quantity of at least one of the following anions--bromate, nitrite, persulfate, and hypochlorite;
- (b) at least about 0.01 grams per liter of at least one of the following metals in the form of a cation--cobalt, nickel, iron, and tin;
- (c) a complexing agent present in an amount sufficient to hold the cation in (b) above in solution;
- and
- (d) sufficient alkaline material to produce a pH of at least 10.5 in the solution.
An aqueous solution for applying a conversion coating to a zinc or zinc alloy surface consisting essentially of:
- (a) at least one of the following:
- (i) from about 0.01 to about 2.5 grams per liter of hypochlorite ion;
- (ii) from about 0.01 to about 18 grams per liter of persulfate ion;
- (iii) from about 0.01 to about 25 grams per liter of nitrite ion;
- and
- (iv) from about 0.01 to about 25 grams per liter of bromate ion;
- (b) at least about 0.01 grams per liter of at least one of the following metals in the form of a cation--cobalt, nickel, iron, and tin;
- (c) a complexing agent present in an amount sufficient to hold the cation in (b) above in solution;
- and
- (d) sufficient alkaline material to produce a pH of at least 10.5 in the solution.
An aqueous concentrate for use in forming a solution for applying a conversion coating to a zinc or zinc alloy surface consisting essentially of:
- (a) one or more of the following anions--bromate, nitrite, and persulfate;
- (b) one or more of the following metals in the form of a cation--cobalt, nickel, iron, and tin;
- (c) a complexing agent to hold the cation in (b) in solution;
- and
- (d) an alkaline material;
- wherein the above ingredients are present in amount sufficient to produce a solution useful for applying a conversion coating to a zinc or zinc alloy surface upon the addition of the concentrate to a controlled quantity of water.
A process for applying a conversion coating to a zinc or zinc alloy surface comprising the steps of:
- (a) contacting the zinc or zinc alloy surface for from about 1 second to about 2 minutes at a temperature in the range of from about 60.degree. to about 212.degree. F. with an aqueous solution comprising;
- (i) a coating accelerating quantity of at least one of the following anions--bromate, nitrite, persulfate, and hypochlorite;
- (ii) at least about 0.01 grams per liter of at least one of the following metals in the form of a cation--cobalt, nickel, iron, and tin;
- (iii) a complexing agent present in an amount sufficient to hold the cation in (b) above in solution;
- and
- (iv) sufficient alkaline material to produce a pH of at least 10.5 in the solution;
- and
- (b) removing excess solution from said surface.
Dependencies are inferred from the claim text.