Biaxially drawn tubular film comprising three adjacent polyamide-based layers

摘要

The invention relates to a biaxially drawn multilayer tubular film consisting of at least five layers, in which the external and two other layers contain aliphatic (co)-polyamide in a quantity equal to or greater than 50% by weight and are differently assembled. The inventive tubular film is produced by coextrusion and, thereby is seamless. Said tubular film can be used in the form of food product packagings, in particular as synthetic sausage casing.

主权项

1. A biaxially drawn tubular film comprising 5 or 7 layers, of which each of the outer layer and the two layers following thereon are immediately adjacent to one another and are aliphatic polyamide-based layers containing at least one aliphatic (co)polyamide, but said layers are otherwise differently composed and
the layer which forms an outside surface of said film consists of 60% to 80% by weight of nylon 6 and 8% to 20% by weight of a thermoplastic copolymer containing carboxyl groups, the 2nd layer from the outside consists of a mixture of 40 to 70% by weight of nylon 6 and 30 to 60% by weight of nylon 6/66, and the 3rd layer from the outside consists of 85 to 95% by weight of nylon 6 and 5 to 15% by weight nylon 6/66, said film further comprises a 4th layer from the outside, an optional 5th layer from the outside, optional 6th layer from the outside, and an inner surface layer, said 4th layer consists of (i) olefin-containing polymer selected from the group consisting of polyethylene or ethylene/α-olefin copolymer grafted with the anhydride of an α,β-unsaturated dicarboxylic acid, ethylene/vinyl acetate copolymers, ethylene/vinyl acetate copolymers, ethylene/(meth)acrylic acid copolymers and their Na or Zn salts, ethylene/(meth)acrylic ester copolymers and corresponding terpolymers and optionally (ii) olefinic (co)polymer, ethylene/α-olefin copolymers, polypropylene, polyethylene, ethylene/propylene copolymers, olefin terpolymer or heterofunctional olefin copolymers, said optional 5th layer consists of olefinic (co)polymer, ethylene/α-olefin copolymers, polypropylene, ethylene/propylene copolymers, olefin terpolymer or heterofunctional olefin copolymers or ethylene/vinyl alcohol copolymer, said optional 6th layer consists of (i) olefin-containing polymer selected from the group consisting of polyethylene or ethylene/α-olefin copolymer grafted with the anhydride of an α,β-unsaturated dicarboxylic acid, ethylene/vinyl acetate copolymers, ethylene/vinyl acetate copolymers, ethylene/(meth)acrylic acid copolymers and their Na or Zn salts, ethylene/(meth)acrylic ester copolymers and corresponding terpolymers; and said inner surface layer comprises nylon 6.