Production of acrylonitrile copolymers
AssigneeImperial Chemical Industries PLC
InventorBrian Norman Hendy
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Abstract
A process which comprises producing a uniform copolymer of acrylonitrile and at least one faster-reacting aromatic olefine containing 50-95% molar of acrylonitrile units wherein the polymerization is conducted in the presence of at least one thiol as chain-transfer agent and the reaction medium is maintained at pH .ltoreq. 4.5, e.g. by using dilute sulphuric acid.
Claims9
A granular polymerization process for producing a uniform copolymer consisting of 50-95% molar of acrylonitrile units, 5-45% molar of units of at least one faster-reacting aromatic olefin selected from the group consisting of styrene and .alpha.-methyl styrene and 0-10% of other ethylenically unsaturated monomers, said copolymer having a reduced viscosity of .ltoreq. 0.75 determined as a 5% solution in dimethyl formamide at 25.degree. C., said process comprising feeding a portion of at least the aromatic olefin to the reaction mixture during the polymerization so that the polymer molecules formed early in the polymerization reaction have substantially the same composition as those formed subsequently and conducting the polymerization in the presence of (a) at least one thiol as chain-transfer agent selected from the group consisting of alkane thiols containing up to 20 carbon atoms, isooctylthioglycolate, trimethylolypropane tri-(3-thiopropronate), thioethanol and .alpha.-thioglycerol, (b) a granulating agent and (c) a momomer soluble initiator, while maintaining the reaction medium at pH .ltoreq. 4.5.
Dependencies are inferred from the claim text.