| 摘要 |
Acrylonitrile or a monomer mixture comprising at least 85% by weight of acrylonitrile is polymerized in an aqueous saline solvent containing at least 55% by weight of ZnCl2, or of a mixture of ZnCl2 and an alkali metal or alkaline earth metal chloride, by continuously feeding the monomer solution and a polymerization initiator solution to a first reactor at such a rate that the monomer conversion therein is not lower than 60% and not higher than 85%; transferring the partially polymerized material to at least one further reactor and carrying out the polymerization in the latter or last reactor so that the conversion reaches at least 92%, wherein the polymerization temperature in any reactor is not lower than 35 DEG C. and not higher than 65 DEG C. Specified comonomers are (meth)acrylic acid, methyl (meth)acrylate, acrylamide, vinyl acetate, alkali metal and alkaline earth metal salts of (meth)allyl sulphonic acid, styrene sulphonates and basic vinyl monomers, e.g. vinyl pyridine and vinyl imidazoles. The chloride other than ZnCl2 may be NaCl, MgCl2 or CaCl2 or mixtures thereof. Initiators specified are H2O2, inorganic persulphates, chlorates or perchlorates, peracetic acid, benzoyl peroxide and Redox systems in which the reducing agent is, e.g., a sulphite, metasulphite, thiosulphite or hydrazine. In the examples, acrylonitrile is copolymerized with methyl acrylate and sodium allylsulphonate in aqueous ZnCl2 solution using as initiator (1) H2O2, (2) ammonium persulphate, (3) sodium persulphate and sodium pyrosulphite and (4) ammonium persulphate and sodium pyrosulphite. |
