Patent GB-1249668-A (GB)
Title: Improvements in the polymerisation of conjugated dienes
IPC: C08F36/04
Filed: 1968-12-24
Abstract: 1,249,668. Diene polymerization using lithiumhydrocarbon adducts. JAPAN GAS-CHEMICAL CO., Inc. 24 Dec., 1968 [29 Dec., 1967], No. 61453/68, Heading C3P. [Also in Division C2] A conjugated diene hydrocarbon is polymerized in a non-polar solvent in the presence of a catalytic amount of an adduct of lithium and a hydrocarbon, said adduct being prepared by reacting metallic lithium with a polycyclic aromatic hydrocarbon having 10 to 30 carbon atoms in an aliphatic ether as solvent, removing from the reaction product insoluble matter, adding to the obtained solution 1 to 10 moles, per gram-atom of lithium in the solution, of a conjugated diene hydrocarbon, or a vinyl- or vinylidene-substituted aromatic hydrocarbon and thereafter removing the aliphatic ether from the resulting solution. Block copolymers may be formed by (i) alternately polymerizing the conjugated diene hydrocarbon and a monoethylenically unsaturated hydrocarbon in an amount such as to provide less than 50% by weight of the block copolymer or (ii) polymerizing the conjugated diene and then introducing a monoethylenically unsaturated monomer in the said amount and polymerizing it to yield a block copolymer in which a block of polymer of the said monomer, e.g. a vinyl- or vinylidene aromatic hydrocarbon, methyl or ethyl acrylate or methacrylate, acrylonitrile or methacrylonitrile, is attached to each end of the block of polymerized diene. In the examples: (a) isoprene is polymerized under N 2  in benzene using a catalyst prepared from lithium, naphthalene and styrene in diethyl ether, the polymerization being terminated by addition of methanol and phenylnaphthylamine being added to the polymer before it is vulcanized conventionally; (b) isoprene is polymerized under argon in benzene using a catalyst prepared from lithium, phenanthrene and styrene in diethyl ether, the polymerization being terminated as under (a) or, alternatively, methyl methacrylate or acrylonitrile being added to the polymer solution to yield a block copolymer; (c) isoprene is polymerized under vacuum in n-heptane or toluene, using a catalyst prepared from lithium, naphthalene and isoprene in tetrahydrofuran; (d) isoprene is polymerized under N 2  in petroleum ether, using the catalyst specified under (c); (e) isoprene is polymerized under argon in n-hexane using the catalyst specified under (b), the resulting polymer being treated as described under (a); (f) isoprene is polymerized under vacuum in benzene using the catalyst specified under (b), the resulting polymer solution being used in the production of a polystyrene-polyisoprene-polystyrene block copolymer; (g) isoprene is polymerized in cyclohexane under N 2  using a catalyst prepared from lithium, diphenyl and isoprene in diethyl ether; (h) butadiene is polymerized under N 2  in benzene using the catalyst specified under (a), the resulting polymer solution being treated with styrene or methyl methacrylate to yield block copolymers; (i) isoprene is polymerized under N 2  in cycloheptane using a catalyst prepared from lithium, stilbene and alpha-methyl styrene in diethyl ether, the resulting polymer being treated as under (a); (j) isoprene is polymerized under N 2  in benzene using a catalyst prepared from lithium, 1- methylnaphthalene and alpha-methyl styrene in dibutyl ether, the resulting polymer being vulcanized and (k) butadiene is polymerized under N 2  in toluene using a catalyst prepared from lithium, anthracene and 1 -phenylbutadiene in diethyl ether.