Coating solutions for zinc surfaces

Claim 2

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.

Claim 3

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.

Claim 4

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.

Claim 5

The aqueous solution of claim 1 wherein the anion in (a) is from about 0.2 to about 1.5 grams per liter of hypochlorite.

Claim 6

The aqueous solution of claim 2 wherein the anion in (a) is from about 0.25 to about 1.0 grams per liter of hypochlorite.

Claim 7

The aqueous solution of claim 2 wherein the anion in (a) is from about 0.5 to about 12 grams per liter of persulfate.

Claim 8

The aqueous solution of claim 2 wherein the anion in (a) is from about 1.0 to about 15 grams per liter of nitrite.

Claim 9

The aqueous solution of claim 2 wherein the anion in (a) is from about 1.0 to about 10 grams per liter of bromate.

Claim 10

The aqueous solution of claim 2 wherein the anion in (a) is present as an alkali metal, calcium or ammonium salt.

Claim 11

The aqueous solution of claim 2 wherein the cation in (b) is present as the nitrate, chloride, sulfate or acetate salt.

Claim 12

The aqueous solution of claim 2 wherein the complexing agent in (c) is present in no more than about 10 grams per liter.

Claim 13

The aqueous solution of claim 2 wherein the complexing agent is sodium gluconate.

Claim 14

The aqueous solution of claim 2 wherein the alkaline material in (d) is an alkali metal hydroxide.

Claim 15

The aqueous solution of claim 2 wherein the alkaline material in (d) is an alkali metal carbonate.

Claim 16

The aqueous solution of claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13 wherein sufficient alkaline material in (d) is present to produce a pH of at least 12.0 in the solution.

Claim 17

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.

Claim 18

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.

Claim 19

The aqueous concentrate of claim 15 wherein the alkaline material in (d) is present in amount sufficient to produce a solution having a pH of at least 12.0 when the concentrate is added to a controlled quantity of water.

Claim 20

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° to about 212° 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.

Claim 21

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° to about 212° 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.

Claim 22

The process of claim 17 wherein the pH of the solution is at least about 12.0.

Claim 23

The process of claim 17 wherein the treatment time is from about 5 seconds to about 15 seconds.

Claim 24

The process of claim 17 wherein the temperature is from about 80° to about 120° F.

Claim 25

The process of claim 17 wherein the excess solution is removed in step (b) by spraying or dipping in water.

Claim 26

The process of claim 17 wherein step (a) is carried out by spraying the solution onto said surface.

Claim 27

The process of claim 17, 18, 19, 20, 21, or 22 wherein the anion in (a) (i) is at least one of the following: (a) from about 0.01 to about 2.5 grams per liter of hypochlorite; (b) from about 0.01 to about 18 grams per liter of persulfate; (c) from about 0.01 to about 25 grams per liter of nitrite; and (d) from about 0.01 to about 25 grams per liter of bromate.

Claim 28

The process of claim 23 wherein the alkaline material in (a) (iv) is an alkali metal hydroxide.

Claim 29

The aqueous solution of claim 23 wherein the alkaline material in (a) (iv) is an alkali metal carbonate.

Claim 30

The process of claim 23 wherein the anion is from about 0.2 to about 1.5 grams per liter of hypochlorite.

Claim 31

The process of claim 23 wherein the anion is from about 0.25 to about 1.0 grams per liter of hypochlorite.

Claim 32

The process of claim 23 wherein the anion is from about 0.5 to about 12 grams per liter of persulfate.

Claim 33

The process of claim 23 wherein the anion is from about 1.0 to about 15 grams per liter of nitrite.

Claim 34

The process of claim 23 wherein the anion is from about 1.0 to about 10 grams per liter of bromate.

Claim 35

The aqueous solution of claim 23 wherein the anion is present as an alkali metal, calcium or ammonium salt.

Claim 36

The process of claim 23 wherein the cation in (a) (ii) is present as the nitrate, chloride, sulfate or acetate salt.