GB811684A - Coating process for polyethylene and composite articles obtained thereby - Google Patents

Abstract

Polyethylene articles, e.g. films which may have a thickness not in excess of 20 mils., tubes, hose, flexible bottles, cartons and boxes, are coated with a resinous tripolymer of vinylidene chloride, acrylonitrile and a functionally acidic ethenoid monomer, by sulphonating the surface of the polyethylene, treating the sulphonated surface with a polybasic compound containing at least two amine groups, e.g. polyamine, alcamine or polyglycol polyamine, to provide said surface with a basic reactive polarity, and subsequently applying a layer of the resinous tripolymer which may have a thickness at least about 0.02 mls. over the amine treated sulphonated surface. Suitable sulphonating agents are concentrated sulphuric acid containing at least about 98 per cent by weight of H2SO4, oleum which may contain from trace amounts to 10 per cent by weight of dissolved free sulphur trioxide, anhydrous solutions, e.g. in acetic anhydride, of oleum, or free sulphur trioxide, e.g. with a suitable inert gas such as nitrogen, and the sulphonation may occur at a temperature between the freezing point of the reagent and 150 DEG C., e.g. about 50 DEG C. for about five minutes. The polybasic compound which may be applied as a dispersion or solution containing 1 to 5 per cent by weight polybasic compounds in a suitable liquid, e.g. water, may be polyvinylpyrrolidone or a normally liquid low molecular weight polyamine, e.g. ethylene diamine, diethylene triamine, triethylenetetraamine. The resinous tripolymer may contain between 40 and 90 per cent by weight vinylidene chloride, 5 to 60 per cent by weight acrylonitrile, and 1 to 15 per cent by weight of a functionally acidic ethenoid monomer, e.g. acrylic acid, sulphonated styrene monomer such as styrene sulphonic acid, and sodium styrene sulphonate, and may be applied dissolved in suitable solvents, e.g. as a lacquer or a latex composition or may be formed in situ.