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Polyolefin Compositions for Heat-Sealable Films Having Controlled Peel Strength



Published February 1, 2005
Related Searches: film
A multilayer film for packaging with a peel strength value from about 1 to 20 N/15 mm and comprising at least one sealing layer with a polyolefin composition has been patented. This composition consists essentially of: a polyethylene, a polypropylene composition and a series of copolymers. The polyethylene, comprising 20-50% of the composition, can be low density, high density or ethylene-vinylacetate copolymer with a melt flow rate higher than 0.3 g per 10 min. Comprising 50-80% is a composition selected from the group consisting of a random copolymer of propylene with 7-40% by weight of a CH2_CHR alkene, where R is an alkyl group containing from 2 to 6 carbon atoms, and from 0.5 to 6% by weight of ethylene as additional comonomer; a composition comprising (a) at least 20% by weight B1, and (b) B2, a random copolymer of propylene with up to 10% by weight of ethylene a composition comprising (a) at least 20% by weight B1; and (b) a propylene homopolymer; and (iv) a composition comprising (a) at least 20% by weight B1; (b) B2, and (c) a propylene homopolymer. The copolymer, representing 1-20% by weight, is selected from the group consisting of copolymers of propylene with 45-60% by weight of one or more CH2_CHR alkenes, where R is an alkyl group containing 2 to 6 carbon atoms or copolymers of propylene with 45-60% by weight of the one or more CH2_CHR alkenes and with 0-6% by weight ethylene; copolymers of 20 to 80% by weight ethylene with one or more CH2_CHR_ alkenes, where R_ is an alkyl group containing from 1 to 6 carbon atoms, the copolymers of ethylene containing from 0-30% of fraction insoluble in xylene at 25°C, or copolymers of 20-80% by weight ethylene with one or more of the CH2_CHR_ alkenes and from 1-10% by weight of a diene. The copolymers of ethylene contain 0-30% by weight of a fraction insoluble in xylene at 25°C and (23) saturated or unsaturated block copolymers, linear or branched, containing at least one comonomer selected from the group consisting of butadiene, butene, ethylene and neoprene.