Claims
- 1. A process for treating the surface of a steel casting die for molten metals which comprises:
- (a) treating an aqueous dispersion of a water-dispersible film-forming polymer having a high polymer fraction, a low polymer fraction and an unsaturated monomeric fraction with a water-soluble peroxide in an amount of from about 3 to about 7.5 parts by weight of the peroxide per 100 parts by weight of the polymer solids so as to bring about the polymerization of the unsaturated monomeric fraction and the further polymerization of the low polymer fraction without however losing the water-dispersible property of the polymer;
- (b) mixing from about 10% to about 48% by weight of boron nitride powder having a particle size less than 200 mesh with the resulting peroxide-modified aqueous dispersion containing from about 10% to about 27% by weight of the peroxide-modified water dispersible film-forming polymer, the balance of the peroxide-modified aqueous dispersion being substantially water;
- (c) applying said peroxide modified aqueous dispersion as a film onto the die surface which contacts the molten metal; and
- (d) allowing the film to dry to form a thermally-insulating, lubricating and protective coating on the die surface.
- 2. The process according to claim 1 wherein the peroxide-modified water-dispersible film-forming polymer is selected from the group consisting of an acrylic polymer, an alkyd resin, a butadiene-acrylonitrile copolymer and a noncarboxylated styrene-butadiene polymer.
- 3. The process according to claim 1 wherein an iron oxide pigment in an amount up to about 50% of the amount of boron nitride powder is mixed with said peroxide-modified aqueous dispersion.
- 4. The process according to claim 1 wherein the molten metal is selected from the group consisting of zinc and zinc alloys.
- 5. A coated casting die for molten metals which comprises a steel casting die having a coating on the die surface which contacts the molten metal produced by the process defined by claim 1 or claim 3.
- 6. The coated casting die according to claim 5 wherein the coating comprises from about 36 to about 180 parts by weight of the peroxide-modified water-dispersible film-forming polymer per 100 parts by weight of the boron nitride powder.
- 7. The coated casting die according to claim 5 wherein the coating thickness range from about 0.02 millimeters to about 0.19 millimeters.
Parent Case Info
This is a division, of application Ser. No. 928,725, filed July 27, 1978 now U.S. Pat. No. 4,195,002.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4202523 |
Radtke |
May 1980 |
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Divisions (1)
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Number |
Date |
Country |
Parent |
928725 |
Jul 1978 |
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