| 摘要 |
Linear polymers are prepared by polymerizing dienes having at least one terminal ethylenically unsaturated bond, by means of a "coordination catalyst" which is a titanium, zirconium, cerium, vanadium, niobium, tantalum, chromium, molybdenum or tungsten compound in which the metal is, at least in part, in a valence state below 3, or is used in the presence of a reducing agent capable of reducing the valence state of the metal, at least in part, to less than 3. Monomers specified are allene, butadiene, 2,4-pentadiene, 1,5-hexadiene, 1,7-octadiene, 1,9-decadiene, isoprene, chloroprene, divinyl and di-isopropenyl benzene, vinyl cyclohexene and mixtures thereof or with monomers such as ethylene, propylene, styrene and vinyl halides. Transition metal compounds specified are titanium tetrachloride, tetrafluoride and oleate; zirconium tetrachloride; niobium pentachloride; vanadium tetrachloride; tantalum pentabromide; cerium trichloride; molybdenum pentachloride; tungsten hexachloride; tetra - (2 - ethylhexyl), tetrapropyl, octylene glycol and triethanolamine titanates; tetraethyl zirconate, and tetra-(chloroethyl) zirconate. The reducing agent may be a Grignard reagent (phenyl magnesium bromide), a metal alkyl (cadmium dialkyl, tin tetra-alkyl, lithium aluminium tetrabutyl or tetra-(ethylcyclohexenyl)), a metal hydride (lithium aluminium hydride, aluminium borohydride) or zinc and metals above zinc in the electromotive series such as sodium and aluminium. The process may be carried out in an inert organic solvent, such as cyclohexane, toluene or xylene, and the polymer if necessary may be precipitated with methanol and washed successively with materials such as methanol, methanol/hydrochloric acid, methanol/sodium hydroxide, water and acetone, or reprecipitated from cyclohexane or carbon disulphide. The examples describe continuous addition of monomer. The products are of high molecular weight, are normally rubbery, may be insolubilized (crosslinked) by heating or by treatment with acid or free-radical catalysts, or may be vulcanized using sulphur or sulphur dioxide and a catalyst. Films and filaments may be produced.ALSO:Lithium aluminium tetra (ethyl cyclohexenyl) is prepared (Example 5) by reacting lithium aluminium hydride with vinyl cyclohexene at a temperature of 128 DEG to 140 DEG C. The reaction may be carried out under a blanket of nitrogen. The product is used in the polymerization of dienes.ALSO:Catalysts used in the polymerization of dienes (see Group IV(a)), consist of a polyvalent metal compound in which the metal is titanium, zirconium, cerium, vanadium, niobium, tantalum, chromium, molybdenum, or tungsten, and is, at least in part, in a valency state below 3, or said compound is in the presence of a reducing agent capable of reducing the valency state of the metal, at least in part, to less than 3. Transition metal compounds specified are titanium tetrachloride, tetrafluoride and oleate; zirconium tetrachloride; niobium pentachloride; vanadium tetrachloride; tantalum pentabromide; cerium trichloride; molybdenum pentachloride; tungsten hexachloride; tetra (2-ethylhexyl), tetrapropyl, octylene glycol and triethanolamine titanates; tetraethyl zirconate and tetra (chloroethyl) zirconate. The reducing agent may be a Grignard reagent (phenyl magnesium bromide), a metal alkyl (cadmium dialkyl, tin tetraalkyl, lithium aluminium tetrabutyl or tetra (ethylcyclohexenyl), a metal hydride (lithium aluminium hydride, aluminium borohydride) or zinc and metals above zinc in the electromotive series (such as sodium and aluminium).
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