Packaging film comprising a blended self-welding layer
AssigneeW. R. Grace & Co.
InventorsAlan S. Weinberg, Joseph Z. Sun
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Abstract
This invention is a self-welding packaging film made by blending at least two ethylene polymers, one of the polymers having a melt flow substantially greater than any of the other polymers in the blend, and thereafter extruding a film from the blend. The film may be self-supporting or it may be an inner layer in a multi-ply film. Preferred ethylene polymers for the blend are the ethylene-vinyl acetate copolymers wherein one copolymer has a melt flow of less than 5.0 and the other has a melt flow greater than 28.0.
Claims13
A self-welding packaging film comprising:
- (a) a self-welding layer comprising a blend of at least two copolymers of ethylene-vinyl acetate, each copolymer having a different melt flow, the melt flow of one copolymer being less than 5.0 and the melt flow of another copolymer being greater than 28.0;
- (b) a substrate layer comprising a cross-linked, heat shrinkable polymeric material said polymeric material selected from the group consisting of polyethylene and ethylene-vinyl acetate copolymers;
- and,
- (c) a layer having low gas permeability, the material for said layer being selected from the group consisting of:
- (1) copolymers of vinylidene chloride;
- (2) polyamides;
- (3) polyesters;
- (4) polyvinyl alcohol;
- (5) acrylonitrile copolymers;
- and,
- (6) hydrolized ethylene vinyl acetate copolymers;
- said substrate layer being located between the self-welding layer and the impermeable layer.
A self-welding packaging film comprising, in order:
- (a) a self-welding layer consisting of a blend of two copolymers of ethylene vinyl acetate, one copolymer having a melt flow in the range of 0.25 to about 3.0 and the other having a melt flow of at least approximately 150;
- (b) a substrate layer comprising a copolymer of ethylene vinyl acetate;
- said substrate layer being heat-shrinkable;
- (c) a layer comprising a copolymer of vinylidene chloride and vinyl chloride;
- (d) a layer comprising a copolymer of ethylene vinyl acetate;
- (e) said layers (a) and (b) having been crosslinked by irradiation at a dosage level in the range of 0.5 MR to 4.0 MR;
- and,
- (f) said film being self-welding in its heat-shrinking temperature range.
A multi-layer, self-welding packaging film comprising:
- (a) a self-welding layer comprising a blend of two polymers,
- (i) one polymer comprising the major portion of the blend and being selected from the group consisting of polyethylenes, ethylene-vinyl acetate copolymers, and ionomers having melt flows less than 5.0 and
- (ii) the other polymer comprising a minor portion of the blend and being selected from the group consisting of ethylene-vinyl acetate copolymers and ethylene terpolymers having melt flows greater than 28.0;
- and,
- (b) at least one additional film layer comprising a polymeric material selected from the group consisting of polyethylenes, ethylene-vinyl acetate copolymers, hydrolyzed ethylene-vinyl acetate copolymers, polyvinyl alcohols, copolymers of vinylidene chloride and vinyl chloride, polyamides, and acrylonitrile copolymers, said additional layer being heat shrinkable.
Dependencies are inferred from the claim text.