Heat shrinkable composite film and packaging method using same

Claim 1

A heat shrinkable composite film comprising as a core at least one of (a) a low density polyethylene having a density of 0.890-0.905 g/cm 3 and a Vicat softening point of 60°-80° C. and/or (b) a copolymer of propylene and one or more α-olefins with 2-8 carbon atoms having a Vicat softening point of 70°-110° C., and two outer layers laminated over the opposite surfaces of said core layer (c) a crystalline polypropylene resin having a melting point of 135°-150° C., said core layer having a thickness of 30-80% of the total thickness of said outer layers and said core layer.

Claim 5

A method of packaging an article which comprises the steps of: providing a heat shrinkable composite film which includes a core layer formed of (a) a straight chain, low density polyethylene having a density of 0.890-0.905 g/cm 3 and a Vicat softening point of 60°-80° C. and/or (b) a copolymer of propylene and one or more α-olefins with 2-8 carbon atoms having a Vicat softening point of 70°-110° C., and two outer layers laminated over the opposite surfaces of said core layer and each formed of (c) a crystalline polypropylene resin having a melting point of 135°-150° C., said core layer having a thickness of 30-80% of the total thickness of said outer layers and said core layer, which exhibits a shrinking force of not greater than 30 g in both longitudinal and transverse direct temperatures providing a shrinkage percentage of at least 35% in both longitudinal and transverse directions and which has a size not greater than 1.6 times the exterior surface area of the article; enclosing the article with the film; and heating said enclosure at a temperature so that the film can be shrunken with a shrinkage percentage of at least 35% in both longitudinal and transverse directions.

Claim 6

A method of packaging an article which comprises the steps of: providing a heat shrinkable composite film which includes a core layer formed of (a) a straight chain, low density polyethylene having a density of 0.890-0.905 g/cm 3 and a Vicat softening point of 60°-80° C. and/or (b) a copolymer of propylene and one or more α-olefins with 2-8 carbon atoms having a Vicat softening point of 70°-110° C., and two outer layers laminated over the opposite surfaces of said core layer and each formed of (c) a crystalline polypropylene resin having a melting point of 135°-150° C., said core layer having a thickness of 30-80% of the total thickness of said outer layers and said core layer, which exhibits a shrinking force of not greater than 30 g in both longitudinal and transverse direct temperatures providing a shrinkage percentage of at least 35% in both longitudinal and transverse directions and which has a size not greater than 1.6 times the exterior surface area of the article; enclosing the article with the film; and heating said enclosure at a temperature so that the film can be shrunken with a shrinkage percentage of at least 35% in both longitudinal and transverse directions.