EVA recycling method
A method of recycling scrap ethylene-vinyl acetate (EVA) foam involves foaming and crosslinking a blend containing virgin EVA resin and scrap EVA foam, as well as a crosslinking agent and blowing agent for the EVA resin. The blend further contains a compatibilizer, which is a hydrogenated petroleum resin.
1. A foaming composition for making a foamed ethylene vinyl acetate copolymer article or articles incorporating recycled ethylene vinyl acetate foam, the composition consisting essentially of:
ethylene vinyl acetate (EVA) copolymer having 15-60 mole percent vinyl acetate;
scrap, at least partially crosslinked ethylene-vinyl acetate foam product;
peroxide crosslinking agent;
blowing agent for the vinyl acetate copolymer;
a compatibilizer comprising a hydrocarbon resin or a hydrogenated petroleum resin, and
optionally, a member selected from the group consisting of foam auxiliaries, foaming inhibitors, fillers, pigments, fire retardants, lubricants, activators, and combinations thereof.
2. A composition according to claim 1 , wherein the compatibilizer comprises a resin produced by polymerizing a C5 cut obtained as a byproduct of petroleum cracking.
3. A composition according to claim 1 , wherein the compatibilizer comprises a resin produced by polymerizing a C9 cut obtained as a byproduct of petroleum cracking.
4. A composition according to claim 1 comprising 1-19 percent by weight of the scrap foam product.
5. A composition according to claim 1 , wherein the peroxide crosslinking agent comprises dicumyl peroxide.
6. A composition according to claim 1 , wherein the blowing agent comprises a diazocarbamide.
7. A composition according to claim 1 , comprising a filler selected from the group consisting of magnesium carbonate, magnesium silicate, and calcium carbonate.
8. A composition according to claim 1 , comprising 1-4 parts of the compatibilizer based on 100 parts of the EVA copolymer.
9. A composition according to claim 1 , comprising 1-19 percent by weight of the scrap foam product and 1-4 parts of the compatibilizer based on 100 parts of the EVA copolymer.
10. A foaming composition for making a foamed ethylene vinyl acetate copolymer article, the mixture comprising:
virgin resin consisting essentially of ethylene vinyl acetate (EVA) copolymer having 15-60 mole percent vinyl acetate;
scrap, at least partially crosslinked ethylene-vinyl acetate foam product;
peroxide crosslinking agent;
blowing agent for the vinyl acetate copolymer; and
a compatibilizer comprising a hydrocarbon resin or a hydrogenated petroleum resin.
11. A composition according to claim 10 , comprising 1-19 percent by weight of the scrap foam product and 1-4 parts of the compatibilizer based on 100 parts of the EVA copolymer.
12. A composition according to claim 10 , comprising from 1 to 30 parts by weight of scrap ethylene-vinyl acetate foam product based on 100 parts by weight of virgin ethylene vinyl acetate (EVA) copolymer and comprising an amount of the compatibilizer that increases tear strength of a foamed article molded from the composition.
13. A composition according to claim 10 , wherein the mixture comprises a single copolymer component consisting essentially of the virgin resin and the scrap ethylene-vinyl acetate foam product.
14. A foamed ethylene vinyl acetate copolymer article comprising:
a crosslinked reaction product of a mixture comprising
ethylene vinyl acetate (EVA) copolymer having 15-60 mole percent vinyl acetate;
scrap, at least partially crosslinked ethylene-vinyl acetate foam product;
peroxide crosslinking agent;
blowing agent for the vinyl acetate copolymer; and
a compatibilizer comprising a hydrocarbon resin or a hydrogenated petroleum resin;
wherein the copolymer article has increased split tear strength, reduced shrinkage, or both as compared to a foamed ethylene vinyl acetate copolymer article that is a crosslinked reaction product of a mixture that is substantially the same but without the compatibilizer.