Blister-pack film for gas-evolving prods. - has ionomer base film with barrier layer from aq. dispersion of vinylidene chloride-methyl acrylate and vinyl chloride-copolymers

摘要

Ionomer resin-based film (I) for blister packaging of gas-evolving prods. is claimed; (I) has a layer of barrier mixt. (II) on the outside, comprising aq. anionic copolymer dispersion (IIA) based on vinylidene chloride (VDC) and methyl acrylate (MA) and an aq. dispersion (IIB) of vinyl chloride (VC)-based copolymer. (I) is produced by applying 2-10 g/m2 of a mixt. of 5-90% (IIA) and 10-80% (IIB) to an ionomer resin base film (opt. after applying a primer), levelling with an air knife and drying the layer obtd.. Pref. amts. are 20-75% (IIA) and 20-60% (IIB); (II) is an aq. dispersion of a copolymer of VC and 5-70 (10-60)% n-butyl acrylate; ratio (IIA):(IIB) = 60:40; amt. applied is as above, pref. after applying primer, esp. a 1- or 2-component adhesive. USE/ADVANTAGE - Useful for packaging prods. which continue to evolve gas, e.g. unripe cheese etc.. Provides a packaging film with min. permeability to oxygen and with CO2-permeability which can be adapted to the properties of the package contents, thus preventing swelling of the pack, growth of mould, etc..