| 摘要 |
Dyeable films, fibres and fabrics are made by treating with a strong oxidizing agent, preferably in an acid medium and at an elevated temperature, a shaped article made from a polyacrylonitrile or copolymer of acrylonitrile substituted by a group containing bivalent sulphur (see Group IV (a)). The introduction of the bivalent sulphur group may be effected on polymers whilst in shaped form and this method of operation may be used to produce locally oxidized structures, e.g. a fabric made from fibres of a copolymer of acrylonitrile containing halogen alkyl agroups is printed with a thiourea or thiocyanate in the presence of thickening agents such as methyl or carboxymethyl cellulose and then reacted by heating, followed by treatment with an oxidizing agent; alternatively a fabric made of an acrylonitrile polymer containing bivalent sulphur groups may be oxidized locally by means of an oxidizing agent in the presence of a resistant or thickening agent such as sodium polystyrene sulphonate. The products of the process show affinity for dyestuffs, particularly basic dyestuffs such as Astra Cyanine B, a triphenylmethane dyestuff.ALSO:Dyeable shaped structures are made by treating with a strong oxidizing agent, preferably in an acid medium and at an elevated temperature, and prior to or after a shaping process, a polyacrylonitrile or copolymer of acrylonitrile substituted by a group containing bivalent sulphur which is either linked directly to a saturated carbon atom of the chain or is linked to the chain by another saturated carbon atom and in which group another carbon atom, adjacent to the sulphur, is linked by more than one valency to another sulphur atom or to oxygen or nitrogen. The sulphur containing groups may be incorporated in the polymer molecules (a) by copolymerizing acrylonitrile with vinyl thioacetate in a dioxane solution with azodiisobutyronitrile as a catalyst, or (b) by causing polyacrylonitrile or copolymers of acrylonitrile to react with compounds such as sodium and ammonium thiocyanates, sodium alkyl xanthates, alkali thio- or dithio-carbamates, ethylene thiourea, N-butyl ethylene thiourea and mercaptobenzothiazole; preferred polymers are copolymers of acrylonitrile with monomers containing reactive groups such as vinyl chlorethyl ether, chloracrylonitrile, chlorethyl methacrylate, hydroxyethyl acrylamide benzene sulphonate, bromobutyl acrylamide and vinyl chloroacetate, and, optionally, other monomers such as methyl acrylamide, vinyl acetate and vinyl pyrrolidone may also be present. Specified oxidizing agents are chlorine or bromine in the presence of water, hypochlorous or hypobromous acid, benzoyl peroxide peracetic or perbenzoic acid, N-chlorurethane and N-chloroxazolidone, the action of which may be accelerated by means of oxygen carriers such as anthraquinone or anthraquinone sulphonic acid. The oxidation reaction is preferably carried out on the polymeric material in the form of fibres or films which may then be dyed, particularly with basic dyestuffs. |
