GB625026A - Improvements in or relating to manufacture of films for wrapping and other purposes - Google Patents

Abstract

Transparent, self-sustaining films are produced by casting upon a support a film of a mixed latex in which is dispersed (1) a polymer or copolymer of vinyl chloride and (2) from 50-300 per cent by weight of (1) of a copolymer of the diene-acrylonitrile type, drying the film, heating to from 275-350 DEG F., cooling and stripping the film from the support. The vinyl resin latices may be dispersions produced by polymerizing vinyl chloride with or without other copolymerizable compounds in an aqueous emulsion, or by dissolving the polymer in a solvent, emulsifying the solution and distilling off the solvent. Compounds with which vinyl chloride may be copolymerized include vinyl organic esters, vinyl bromide, vinylidene chloride, tetrafluorethylene, methyl methacrylate, acrylonitrile, vinyl ethers, thioethers and vinyl ketones. Suitable dienes are butadiene, isoprene, chloroprene, 1-methyl-1,3-butadiene and 2,3 - dimethyl - 1,3 - butadiene. Suitable acrylonitrile-type compounds are acrylonitrile, methyl, ethyl and propyl acrylonitrile and chloroacrylonitrile. The diene copolymers preferably consist mainly of the "sol" type prepared, for example, by polymerizing in the presence of modifying agents such as alkyl mercaptans and thiophenols. After drying the film, at temperatures of about 125 DEG F., the heating at higher temperatures is continued until the mixture is homogeneous. Plasticizers, stabilizers, fillers, dyes and pigments may be added to the dispersions, those, e.g. dioctyl phthalate, which are insoluble in water, being emulsified first with the aid of, for example, ammonia, red oil and calcium stearate. The films may be used for wrapping purposes, as photographic film base, sound bands and curtainings.ALSO:Transparent, self-sustaining films are produced by casting upon a support a film of a mixed latex in which is dispersed (1) a polymer or copolymer of vinyl chloride and (2) from 50 per cent - 300 per cent by weight of (1) a copolymer of the diene-acrylonitrile type, drying the film, heating to from 275 DEG - 350 DEG F., cooling and stripping the film from the support. The vinyl resin latices may be dispersions produced by polymerising vinyl chloride with or without other copolymerisable compounds in an aqueous emulsion, or by dissolving the polymer in a solvent, emulsifying the solution and distilling off the solvent. Compounds with which vinyl chloride may be copolymerised include vinyl organic esters, vinyl bromide, vinylidene chloride, tetrafluorethylene, methyl methacrylate, acrylonitrile, vinyl ethers, thioethers and vinyl ketones. Suitable dienes are butadiene, isoprene, chloroprene, 1-methyl-1,3-butadiene and 2,3-dimethyl-1,3-butadiene. Suitable acrylonitrile-type compounds are acrylonitrile, methyl, ethyl and propyl acrylonitrile and chloroacrylonitrile. The diene copolymers preferably consist mainly of the "sol" type, prepared, for example, by polymerising in the presence of modifying agents such as alkyl mercaptans and thiophenols. After drying the film, at temperatures of about 125 DEG F., the heating at higher temperatures is continued until the mixture is homogenous. Plasticisers, stabilisers, fillers, dyes and pigments may be added to the dispersions, those, e.g. dioctyl, phthalate, which are insoluble in water being emulsified first with the aid of ammonia, red oil and calcium stearate. The films may be used for wrapping purposes, as photographic film base, sound bands and curtainings.