| 摘要 |
A polymerization catalyst comprises a metal salt coated on the surface with a very thin layer, which may be from 1 to 1,000 molecules thick, of a salt of a different metal. The supporting metal may have an atomic weight from 24 to 209 and be from Group II, III, VII or VIII, in particular cobalt, magnesium or cerium and may be in the form of a sulphide, silicide, phosphide or preferably halide; its crystals may have a size between 1 and 300 mesh (ASTM). The coating metal salt may be a sulphate, nitrate, sulphide, chlorate, or preferably halide of a metal from Group III, IV, V or VIII having an atomic volume of less than 20, in particular a halide of titanium, vanadium or zirconium. The coating layer is advantageously 10-100 molecules thick or 0,1 - 5 mg. per 1g. of metal salt carrier. The catalyst may be made by a vacuum-plating technique in which a solution of the coating metal salt (e.g. TiCl4 in heptane) is deposited upon the supporting metal salt (e.g. CoCl2) crystals with the subsequent removal of the sovlent. Examples are given in which propylene, ethylene or styrene are polymerized (see also Group IV(a)).ALSO:A process for polymerizing unsaturated monomers comprises contacting the monomer in the absence of molecular oxygen and water with a catalyst composition comprising a metal salt coated on the surface with a molecularly thin layer of a salt of a different metal (see Group III). The supporting salt may be a halide, sulphide, silicide or phosphide of cobalt, magnesium or cerium. The salt coating may be a halide, sulphate, sulphide, nitrate or chlorate of titanium, vanadium or zirconium. Metal alkyls such as diethyl aluminium chloride and aluminium triethyl may be used as co-catalysts. Many monomers are specified among which are ethylene, propylene, octadecene, butadiene, methyl acrylate, vinyl chloride, vinylidene bromide, acrylonitrile, vinyl acetate, divinyl succinate, diallyl phthalate, vinyl crotonate, diallyl ether, vinyl butyl ketone. An induction period of 1-2 hours may be reduced by pretreatment of the catalysts with monomer. Inert solvents may be employed such as octane, iso-octane, n-heptane, xylene or benzene. Other additives that may be included are hydrogen, oxygen, acetylene, pyridine, ethyl acetate, tributyl phosphite, phenols and titanium halides. The polymers obtained from propylene, butene and styrene have melting points of 90-330 DEG C., molecular weights of 50,000-1,000,000 and have an isotactic structure. Examples are given. |
