Coating bath composition and method
AssigneeOxy Metal Industries Corporation
InventorJohn K. Howell, Jr.
Life of this patent
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Abstract
An organic coating bonded to a metallic substrate and applied from an acidic, aqueous coating composition containing epoxy resin solids and a cross linking resin. The resin solids are incorporated into the coating composition as an emulsion in a water insoluble solvent, so that the reactive resin is isolated from the acidic aqueous medium. The novel composition and the novel method result in a coating which can be pigmented and which can be utilized as a final corrosion resistant coating or as an undercoat for a later applied finish coat.
Claims9
The method of applying a bonded organic coating to a ferrous substrate comprising the steps of:
- (1) combining an epoxy resin, a cross linking resin, a resin-miscible water-immiscible solvent and at least one emulsifying agent wherein the weight ratio of epoxy resin:
- cross linking resin is from about 1:1 to about 9:1;
- (2) adding sufficient water and hydrogen peroxide to the combination of step 1 to yield an emulsion having a solids content of from about 5 to about 500 grams per liter and containing from about 1 to about 5 grams per liter of hydrogen peroxide as an oxidizing agent;
- (3) adding sufficient acid or base, if necessary, to adjust the pH value of the emulsion to from about 2 to about 4;
- (4) immersing a ferrous substrate into the coating bath to form a coating thereon;
- and
- (5) heat curing the coating.
The method of applying a bonded organic coating to a ferrous substrate comprising the steps of:
- (1) forming a solution of an epoxy resin and a cross-linking resin selected from the group consisting of aminoplast and phenoplast resins in a resin-miscible water-immiscible solvent wherein the weight ratio of epoxy resin:cross linking resin is from about 1:1 to about 9:1;
- (2) adding at least one emulsifying agent;
- (3) forming an aqueous acidic emulsion coating bath by adding an acid capable of attacking the ferrous substrate in an amount to yield a bath pH of from about 2 to about 4, sufficient water to yield a bath having a resin solids content of from about 5 to about 500 grams per liter and from about 1 to about 5 grams per liter of hydrogen peroxide,
- (4) immersing the ferrous substrate into the coating bath to form a coating thereon, and
- (5) heat curing the coating.
The method of applying a bonded organic coating to a ferrous substrate comprising the steps of:
- (1) forming an aqueous emulsion of an epoxy resin and a cross-linking resin, both in a water-immiscible solvent, and at least one emulsifying agent wherein the weight ratio of epoxy resin:cross linking resin is from about 1:1 to about 9:1,
- (2) forming an aqueous acidic coating bath containing the emulsion of step 1, having a pH of from about 2 to about 4, a solids content of from about 5 to about 500 grams per liter, containing from about 1 to about 5 grams per liter, containing from about 1 to about 5 grams per liter of hydrogen peroxide and containing an amount of iron control agent sufficient to control the build up of soluble iron,
- (3) immersing a ferrous substrate into the coating bath to form a coating thereon, and,
- (4) heat curing the coating.
Dependencies are inferred from the claim text.