Back to results
US 4,229,241 AGranted
Process for making a multi layer polyolefin shrink film
AssigneeW. R. Grace & Co.
InventorWalter B. Mueller
Life of this patent
Estimating the term…
Abstract
The multi-layer polyolefin shrink film of this invention provides shrink tensions, optical clarity, cuttability, sealability, shrink temperature range, and tear resistance heretofore unobtainable in an oriented, monolayer polyolefin material. The preferred film has three layers in which the core layer comprises a blend of ethylene-vinyl acetate copolymer with ethylene-butylene copolymer and each skin layer comprises ethylene-propylene copolymer.
Claims5
A process for making a multi-layer, flexible, thermoplastic packaging film comprising the steps of:
- (a) blending 70% to 90% by weight of polymer selected from the group consisting of homopolymers and copolymers of ethylene with 30% to 10% by weight of a polymer selected from the group consisting of butylene homopolymers and copolymers to form a core blend;
- (b) providing an auxiliary composition comprising a polymer selected from the group consisting of propylene homopolymers and copolymers;
- (c) coextruding a layer of said core blend between two layers of said auxiliary composition to form a multi-layer film, said core layer being 1 to 8 times the thickness of said auxiliary layers;
- and,
- (d) stretching said multi-layer film to orient same.
2 more elements
Dependencies are inferred from the claim text.