High free shrink, high modulus, low shrink tension thermoplastic film with elastic recovery

摘要

Disclosed herein is a heat shrinkable thermoplastic film comprising: (a) a core layer comprising at least about 65 percent by weight of a homogeneous alpha-olefin/cyclic olefin random copolymer having a glass transition temperature of from about 25 DEG C to about 45 DEG C; (b) a first outer layer comprising at least one olefinic polymer selected from ethylene/alpha olefin copolymer, ethylene/vinyl acetate copolymer, ethylene/alkyl acrylate copolymer, ethylene/acrylic acid copolymer, ionomer, propylene homopolymer, propylene copolymer, butylene homopolymer, butylene copolymer, low density polyethylene, high density polyethylene, and multi component ethylene/alpha-olefin interpenetrating network resin; and (c) a second outer layer comprising at least one olefinic polymer selected from ethylene/alpha olefin copolymer, ethylene/vinyl acetate copolymer, ethylene/alkyl acrylate copolymer, ethylene/acrylic acid copolymer, ionomer, propylene homopolymer, propylene copolymer, butylene homopolymer, butylene copolymer, low density polyethylene, high density polyethylene, and multi component ethylene/alpha-olefin interpenetrating network resin; wherein the film has: (i) a Young's modulus of between about 50,000 pounds and about 200,000 pounds per square inch in at least one of the longitudinal and transverse directions; (ii) a free shrink of between about 10% and about 80% at 240 DEG F in at least one of the longitudinal and transverse directions; and (iii) a shrink tension of less than about 400 pounds per square inch at 240 DEG F in at least one of the longitudinal and transverse directions. First and second intermediate layers including an ethylene copolymer having a melt index less than about 2.0 g/10 minutes can be optionally included. Alternatively, a film includes a core layer including an ethylene copolymer having melt index less than about 2.0 g/10 minutes; first and second intermediate layers including a homogeneous random alpha-olefin/cyclic olefin copolymer; and first and second outer layers including an olefinic polymer. These films having properties as disclosed above are suitable for packaging purposes.