Claims
- 1. A metal container coating composition comprising
- (a) about 45 to 95 wt% of a stable aqueous vinyl chloride-ethylene copolymer emulsion, the copolymer having a T.sub.g from 0.degree. to 50.degree. C., consisting of (i) about 65 to 90 wt% vinyl chloride and (ii) ethylene, and prepared by emulsion polymerization of vinyl chloride monomer and ethylene in the presence of an emulsifying system consisting essentially of about 3 to 15 wt% polyvinyl alcohol which is 70 to 91 mole% hydrolyzed, which emulsion polymerization process comprises
- forming an aqueous emulsion reaction mixture in a reaction vessel containing substantially all the polyvinyl alcohol and at least 5% to no more than about 60% of the total vinyl chloride monomer,
- pressurizing the reaction mixture with an ethylene pressure sufficient to provide the copolymer with the requisite ethylene content,
- initiating the reaction mixture by the addition of a free radical generating source and continuing polymerization until the rate of polymerization begins to decrease,
- adding the remaining vinyl chloride monomer over a period of time while continuing polymerization until the reaction is no longer self-sustaining, and
- removing the unreacted ethylene and reducing the vinyl chloride free monomer content of the emulsion,
- (b) about 5 to 40 wt%, based on emulsion solids, of a crosslinking resin,
- (c) up to about 10 wt% organic cosolvent, and
- (d) 0 to 5 wt% acid catalyst.
- 2. The metal container coating composition of claim 1 in which the emulsion polymerization is performed in the presence of about 4 to 10 wt% polyvinyl alcohol.
- 3. The metal container coating composition of claim 2 in which the copolymer is about 75 to 80 wt% vinyl chloride and 20 to 25 wt% ethylene and has a T.sub.g from 20.degree. to 35.degree. C.
- 4. The metal container coating composition of claim 1 in which the emulsion polymerization is performed in the presence of a polyvinyl alcohol which is 85 to 89 mole% hydrolyzed.
- 5. The metal container coating composition of claim 1 in which the emulsion polymerization is performed using a free radical generating source comprising hydrogen peroxide and ascorbic acid or erythorbic acid as the redox system.
- 6. The metal container coating composition of claim 3 in which the emulsion polymerization is performed using a free radical generating source comprising hydrogen peroxide and ascorbic acid or erythorbic acid as the redox system.
- 7. The metal container coating composition of claim 1 in which the copolymer is prepared by emulsion polymerization in the presence of an 87-89 mole% hydrolyzed polyvinyl alcohol.
- 8. The metal container coating composition of claim 2 in which the copolymer is prepared by emulsion polymerization in the presence of an 87-89 mole% hydrolyzed polyvinyl alcohol.
- 9. The metal container coating composition of claim 3 in which the copolymer is prepared by emulsion polymerization in the presence of an 87-89 mole% hydrolyzed polyvinyl alcohol.
- 10. The metal container coating composition of claim 4 in which the copolymer is prepared by emulsion polymerization in the presence of an 87-89 mole% hydrolyzed polyvinyl alcohol.
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application is a continuation-in-part application of Application Ser. No. 622,592 filed June 20, 1984, now abandoned, which is a continuation-in-part application of Application Ser. No. 572,726 filed Jan. 20, 1984, now abandoned.
US Referenced Citations (17)
Foreign Referenced Citations (5)
Number |
Date |
Country |
51-26988 |
Mar 1976 |
JPX |
55-157608 |
Dec 1980 |
JPX |
889645 |
Feb 1962 |
GBX |
991536 |
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GBX |
1043630 |
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GBX |
Continuation in Parts (2)
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Number |
Date |
Country |
Parent |
622592 |
Jun 1984 |
|
Parent |
572726 |
Jan 1984 |
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