| 摘要 |
<p>Heat-sealable packaging film producing a peelable seal, process for the preparation thereof and packages made therefrom or comprising such a film. This film produces such a seal on a wide range of packaging films, including polyester, polyvinyl chloride, polyamide and polyacrylonitrile films owing to: 1. its chemical composition which comprises: (a) 55 to 95% by weight of at least one ethylene polymer selected from polyethylene having a density of from 0.91 to 0.93 g/cm3 and an ethylene-vinyl acetate copolymer containing at most 10% by weight of vinyl acetate, (b) 5 to 30% by weight of polystyrene, and (c) 0 to 20% by weight of a thermoplastic, elastomeric styrene-butadiene-styrene or styrene-isoprene-styrene block copolymer, and 2. the fact that that face of the film which is intended to from the peelable seal, has a surface tension of from 35 to 50, preferably of 37 to 45 millinewtons per meter. The film is prepared by extrusion followed by a corona discharge pretreatment of sufficient intensity of the said face.</p> |
