Oxygen barrier oriented film
AssigneeW. R. Grace & Co., Cryovac Div.
InventorGautam P. Shah
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Abstract
A coextruded multiple layer oriented film comprises a core layer of a blend of ethylene vinyl alcohol copolymer and polyamide, two intermediate adhesive layers, and two outer layers of a blend of linear low density polyethylene, linear medium density polyethylene, and ethylene vinyl acetate copolymer. A preferred embodiment of the multilayer film exhibits excellent optics and shrink properties while providing high oxygen barrier especially useful in food packaging applications.
Claims16
An oriented multilayer film comprising:
- (a) a cross-linked core layer comprising a blend of an ethylene vinyl alcohol copolymer and a polyamide resin, said blend forming between about 5% and 25% of the total film thickness;
- (b) two cross-linked interior layers each comprising an adhesive resin;
- (c) two cross-linked outer layers each comprising a three-component blend of a linear low density polyethylene, a linear medium density polyethylene, and an ethylene vinyl acetate copolymer;
- and
- (d) said film having a total thickness ranging from about 0.75 to 1.5 mils.
An oriented five-layer film comprising:
- (a) a cross-linked core layer comprising a blend of (1) from about 80%, by weight, to about 99%, by weight, of an ethylene vinyl alcohol copolymer and (2) from about 1%, by weight, to about 20%, by weight of a polyamide resin, said blend forming between about 5% and 25% of the total film thickness;
- (b) two cross-linked interior layers each comprising an adhesive resin;
- (c) two cross-linked surface layers each comprising a blend of (1) from about 40%, by weight, to about 60%, by weight, of a linear low density polyethylene, (2) from about 20%, by weight, to about 30%, by weight of a linear medium density polyethylene, and (3) from about 20%, by weight, to about 30%, by weight, of an ethylene vinyl acetate copolymer;
- and
- (d) said film having a total thickness ranging from about 0.75 to 1.5 mils.
An oriented five-layer film comprising:
- (a) a cross-linked core layer comprising a blend of (1) about 90%, by weight, of an ethylene vinyl alcohol copolymer, and (2) about 10%, by weight, of a polyamide resin, said blend forming between about 5% and 25% of the total film thickness;
- (b) two cross-linked interior layers each comprising an acid or acid anhydride-modified polymeric material;
- (c) two cross-linked surface layers each comprising a blend of (1) about 50% by weight, of a linear low density polyethylene, (2) about 25%, by weight, of a linear medium density polyethylene and (3) about 25%, by weight, of an ethylene vinyl acetate copolymer;
- and
- (d) said film having a total thickness ranging from about 0.75 to 1.5 mils.
A method of making an oriented multilayer barrier film having a total thickness ranging from about 0.75 to 1.5 mils comprising:
- (a) simultaneously coextruding a core layer of a blend of an ethylene vinyl alcohol copolymer and a polyamide resin, two intermediate layers of an adhesive material, and two outer layers of a blend of a linear low density polyethylene, a linear medium density polyethylene, and an ethylene vinyl acetate copolymer;
- (b) rapidly cooling the coextruded film;
- (c) collapsing the cooled film;
- (d) irradiating the cooled film with between about 3 and 13 megarads of irradiation;
- (e) heating the irradiated film to a temperature between about 105.degree. C. and 115.degree. C.;
- and
- (f) stretching and orienting the heated film.
Dependencies are inferred from the claim text.