GB604138A - Improvements in or relating to self-sustaining flexible films - Google Patents

Abstract

A flexible film comprises a chlorinated rubber, hydrochlorinated rubber or chlorinated-hydrochlorinated rubber and an elastic copolymer derived from a diolefin of the type <FORM:0604138/IV(a)/1> and an acrylonitrile of the type <FORM:0604138/IV(a)/2> in which formul R represents hydrogen or a methyl radical, R1 represents hydrogen, chlorine or a methyl radical and R11 represents hydrogen, or a methyl, ethyl, propyl or chloro radical. Suitable diolefines are butadiene, isoprene, 1-methyl-1, 3-butadiene, 2,3-dimethyl-1,3-butadiene, and 2-chloro-1,3-butadiene. The acrylonitriles include acrylonitrile, methyl acrylonitrile, ethyl acrylonitrile, propyl acrylonitrile and chloro acrylonitrile. The copolymers may be prepared with the addition of modifying agents such as alkyl mercaptans and dialkyl xanthogen disulphides as described in U.S.A. Specification 2,281,613, and are preferably precipitated from their latices by an alcohol or ketone. Moisture may be removed by the use of a water miscible solvent which is removed at a low temperature. The copolymer and rubber derivative may be compounded by means of rubber mills or may be dissolved in solvents such as methyl ethyl ketone, cyclo-hexanone and dioxane. An antioxidant consisting of a mixture of stannous tertiary-butyl catecholate and didodecyl disulphide, petronising agents such as hexamethylene tetramine and tetramethyl thiuram disulphide described in U.S.A. Specification 2,148,831, plasticizing agents such as dibutyl phthalate, tricresyl phosphate and dibutyl sebacate, carbon black, zinc oxide, polyvinyl chloride and acetate, phenolic and coumarone resins and rosin may be added. Specification 556,213, [Group V], is referred to.ALSO:A self-sustaining flexible film comprises a chlorinated rubber, hydrochlorinated rubber or chlorinated-hydrochlorinated rubber together with an elastic copolymer of a conjugated diolefin with an acrylonitrile, the acrylonitrile content of the copolymer being from 10 to 90 per cent and the copolymer being present to the extent of 10 to 900 per cent based on the weight of the rubber derivative. The copolymer may be derived from a diolefin of the type <FORM:0604138/V/1> and an acrylonitrile of the type <FORM:0604138/V/2> in which formulae R represents hydrogen or a methyl radical, R1 represents hydrogen, chlorine or a methyl radical, and R11 represents hydrogen, or a methyl, ethyl, propyl or chloro radical. Suitable diolefines are butadiene, isoprene, 1-methyl-1, 3-butadiene, 2, 3-dimethyl-1, 3-butadiene, and 2-chloro-1, 3-butadiene. The acrylonitriles include acrylonitrile, methyl acrylonitrile, ethyl acrylonitrile, propyl acrylonitrile and chloro acrylonitrile. The copolymer may be prepared according to known methods with the addition of modifying agents such as alkyl mercaptans and dialkyl xanthogen disulphides as is described in U.S.A. Specification 2,281,213, preferably they are precipitated from their latices by an alcohol or ketone to avoid the use of inorganic salts. If required in the dry state the moisture may be removed by the use of a water miscible solvent which is removed at as low a temperature as possible. The copolymer and rubber derivative may be compounded by means of rubber mills or may be dissolved together in solvents such as methyl ethyl ketone, cyclo-hexanone and dioxane. If required an antitoxidant consisting of a mixture of stannous tertiary-butyl catecholate and didodecyl disulphide may be incorporated. Petronising agents such as hexamethylene tetramine and tetramethyl thiuram disulphide described in U.S.A. Specification 2,148,831, and plasticising agents such as dibutyl phthalate, tricresyl phosphate and dibutyl sebacate and other substances such as carbon black, zinc oxide, polyvinyl chloride and acetate phenolic and coumarone resins and rosin may also be added. The compositions are of two types-homogenous materials which are transparent and remain so under mechanical stress, these may be used for wrapping foods; and heterogenous materials which have greater dimensional stability. Specification 556,213 is referred to.ALSO:Dehydrated and frozen foods and bakery goods are protected against moisture changes by wrapping them in the flexible film comprising a chlorinated rubber, hydrochlorinated rubber or chlorinated-hydrochlorinated rubber together with an elastomeric copolymer of a conjugated diolefin with an acrylonitrile, the acrylonitrile content of the copolymer being from 10 to 90 per cent.; and the copolymer being present in the composition to the extent of from 10 to 900 per cent. based on the weight of the rubber derivative, which is described in Group V.