Linear polyethylene stretch/shrink films
AssigneeW. R. Grace & Co., Cryovac Div.
InventorWalter B. Mueller
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Abstract
A multi-layered thermoplastic polyolefin film having an improved combination of physical characteristics is disclosed. In particular, the multi-layered film evidences an improved combination of elongation, elastic memory, tear resistance and heat shrinkability. Preferred five layer embodiments of the film comprise (1) a core layer of either a low density polyethylene homopolymer or an ethylene vinyl acetate copolymer or a blend of an ethylene vinyl acetate copolymer with a linear low density polyethylene; (2) two adjacent intermediate layers of a linear low density polyethylene and (3) two surface layers of an ethylene vinyl acetate copolymer.
Claims6
In a multilayer, thermoplastic packaging film having a layer of ethylene-vinyl acetate copolymer and a layer of linear low density polyethylene, the improvement wherein:
- (a) said film comprises at least five layers;
- (b) the material of the central or core layer is selected from the group consisting of:
- (1) ethylene-vinyl acetate copolymers, and
- (2) blends of ethylene-vinyl acetate copolymer with linear low density polyethylene;
- (c) intermediate layers adjacent each side of the core layer, said intermediate layers consisting essentially a linear low density polyethylene;
- (d) two surface layers consisting essentially of a copolymer of ethylene-vinyl-acetate;
- (e) said film having a shrink tension at 205.degree. F. in the transverse and longitudinal directions of approximately 400 p.s.i. or greater;
- and,
- (f) said film having an elongation at break at 73.degree. F. in both transverse and longitudinal directions of at least approximately 200%.
A multilayer, thermoplastic film consisting of:
- (a) a core layer consisting essentially of a polymer selected from the group consisting of (i) ethylene-vinyl-acetate copolymers and (ii) blends ethylene-vinyl-acetate copolymers with linear low density polyethylene;
- (b) two intermediate layers, each intermediate layer being adjacent an opposed side of said core layer and each intermediate layer consisting essentially of linear low density polyethylene;
- and,
- (c) two surface layers, each surface layer being adjacent a respective intermediate layer and each surface layer consisting essentially of an ethylene-vinyl-acetate copolymer.
Dependencies are inferred from the claim text.