Patent NZ-581067-A (NZ)
Title: Easy opening packaging article made from heat-shrinkable film exhibiting directional tear
Inventor: STOCKLEY H
IPC: B32B27/08
Filed: 2008-05-20
Abstract: Disclosed is a heat-shrinkable packaging article comprising a heat-shrinkable multilayer film having an inside seal layer heat sealed to itself at a heat seal, the article further comprising a first side, a second side, and a skirt or header outward of the heat seal, the skirt or header comprising an article edge and a first tear initiator, the first tear initiator being in the first side of the article, the article skirt or header also comprising a second tear initiator, the second tear initiator being in the second side of the article, the article being capable of having a manually-initiated, manually propagated first tear in the first side of the article, and a manually-initiated and manually-propagated second tear in the second side of the article, the first tear and the second tear each being capable of being propagated in a machine direction from the respective first and second tear initiators, with each tear being propagated in the machine direction through the heat seal and down the length of the article, or across the article, with each tear being capable of being manually propagated in the machine direction through and to an opposite article edge, so that upon using the multilayer film to make a packaged product by providing a product inside the article with the article being sealed closed around the product so that a package is formed, and thereafter shrinking the film around the product, the resulting package can be manually opened, and the product readily removed from the article, by manually initiating machine-direction tears from the first and second tear initiators, with the tears being manually propagated through the seal and toward the opposite edge of the article, with the multilayer film exhibiting a Peak Load Impact Strength of at least 50 Newtons per mil measured using ASTM D 3763-95A, with at least one layer of the multilayer film comprising at least one member selected from the group consisting of (1) at least one incompatible polymer blend selected from the group consisting of: (A) a blend of from 90 to 30 weight percent ethylene homopolymer and/or ethylene/alpha-olefin copolymer with from 10 to 70 weight percent ethylene/unsaturated ester copolymer having an unsaturated ester 30 content of at least 10 weight percent; (B) a blend of ionomer resin with ethylene/unsaturated ester copolymer, and/or polybutylene, and/or propylene homopolymer and/or propylene copolymer; (C) a blend of homogeneous ethylene/alpha-olefin copolymer with recycled polymer blend comprising ethylene homopolymer, propylene homopolymer, ethylene copolymer, propylene copolymer, polyamide, ethylene/vinyl alcohol copolymer, ionomer resin, anhydride-modified ethylene/alpha-olefin copolymer, and/or antiblock; (D) a blend of from 10 to 75 weight percent ethylene/unsaturated ester copolymer with from 90 to 15 weight percent polypropylene and/or propylene/ethylene copolymer, and/or polybutylene, and/or modified ethylene/alpha-olefin copolymer, and/or styrene homopolymer, and/or styrene/butadiene copolymer; (E) a blend of ethylene/norbornene copolymer with ethylene/unsaturated ester copolymer and/or polypropylene and/or polybutylene; (F) a blend of from 90 to 15 weight percent ethylene/alpha-olefin copolymer with from 10 to 75 weight percent polypropylene and/or polybutylene and/or ethylene/norbornene; (G) a blend of from 90 to 25 weight percent homogeneous propylene homopolymer and/or homogeneous propylene copolymer with from 10 to 75 weight percent homogeneous ethylene/alpha-olefin copolymer and/or ethylene/unsaturated ester copolymer; (H) a blend of propylene homopolymer and/or propylene/ethylene copolymer and/or polybutylene with ethylene/methyl acrylate copolymer and/or ethylene/acrylic acid copolymer and/or ethylene/butyl acrylate copolymer; (I) a blend of polyamide with polystyrene and/or ethylene/alpha-olefin copolymer and/or ethylene/vinyl acetate copolymer and/or styrene/butadiene copolymer; and (J) a blend of polyamide 6 and polyamide 616T; (2) a blend of at least one member selected from the group consisting of ethylene/alpha-olefin copolymer, polypropylene, propylene/ethylene copolymer, polybutylene, styrene/butadiene copolymer, ionomer resin, ethylene/vinyl acetate copolymer, ethylene/butyl acrylate copolymer, ethylene/methyl acrylate copolymer, ethylene/acrylic acid copolymer, polyester, and polyamide, with an inorganic filler selected from the group consisting of silicates, silica, siloxane, silicone resin, zinc sulfide, wollastonite, microspheres, glass fiber, metal oxide, calcium carbonate, sulfate, aluminum trihydrate, feldspar, perlite, gypsum, iron, fluoropolymer, crosslinked polymethylmethacrylate, talc, diatomaceous earth, zeolites, mica, kaolin, carbon black, and graphite, wherein the inorganic filler is present in the layer in an amount of at least 5 weight percent, based on layer weight; and (3) a polymer having a Young's modulus of at least 80,000 psi, wherein the polymer comprises at least one member selected from the group consisting of high density polyethylene, ultra high molecular weight polyethylene, polypropylene, styrene copolymer, ethylene/norbornene copolymer, polycarbonate, and polyester. Also disclosed is a process for preparing the packaging and a packaging prepared by that process.