Patent ID: 6033775
Filing Date: 2000-03-07
Classification: B32B,C08F,C08L,Y10S,Y10T

Abstract:
A stretch wrapping film comprising:a first layer comprising a propylene-based block copolymer (a) obtainable by a polymerization process comprising a first step of forming portion (A) which is a propylene-ethylene copolymer having a content of repeating unit derived from ethylene of 1.5 to 6% by weight, said portion (A) forming 40 to 85% by weight of said propylene-based block copolymer, and a second step of forming of portion (B) which is a propylene-ethylene copolymer having a content of repeating unit derived from ethylene of 7 to 17% by weight, said portion (B) forming 15 to 60% by weight of said propylene-based block copolymer, the intrinsic viscosity of portion (B), ([.eta.]B), being 2 to 5 dl/g, and the ratio ([.eta.]B/[.eta.]A) of the intrinsic viscosity of portion (B) ([.eta.]B), to the intrinsic viscosity of portion (A) ([.eta.]A), being 0.5 to 1.8, anda second layer comprising a polyethylene based resin (b) laminated on at least one surface of the first layer wherein said stretch wrapping film is unoriented or uniaxially oriented and said polyethylene based resin is at least one resin selected from the group consisting of low-density polyethylenes, intermediate-density polyethylenes, high-density polyethylenes, copolymers of ethylene and an .alpha.-olefin having 3 to 10 carbon atoms ethylene copolymers obtained from ethylene and an unsaturated compound ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, and ethylene-methacrylic acid copolymers.