Verfahren zur Herstellung von Verpackungsfilmen und nach diesem Verfahren hergestellte Verpackungsfilme

Coffee beans or ground coffee and other substances which deteriorate easily when exposed to air, are preserved by wrapping in a film of crystalline alpha-olefin polymer coated with a vinylidene chloride-acrylonitrile and an isocyanate adhesive. The film which may be of polypropylene, may be obtained by extrusion, and may be stretched in one or two directions, or may be treated thermally, by a continuous non-perforating electric discharge, or by a chemical agent, e.g. halogenating agents such as chlorine, sulphonating agents such as sulphur trioxide, or oleum, chlorosulphonic acid, and oxidizing agents such as potassium chromate or sulphuric and nitric acids, prior to coating. The adhesive may be a condensation product of toluene diisocyanate with hexanetriol. The coating can be applied in the form of a solution or dispersion in water or organic solvent.