Patent GB-778639-A (GB)
Title: Improvements in or relating to the preparation of polyethylene and copolymers of ethylene
IPC: C08F2/00
Filed: 1955-08-03
Abstract: Ethylene is polymerized under substantially anhydrous conditions in an inert organic solvent using a catalyst comprising a compound of Ti, Zr, Ce, V, Nb, Ta, Cr, Mo or W, said metal being present at least in part in a valency state of 2, or the compound being associated with sufficient of an alkali metal-aluminium-tetrahydrocarbon, an alkali metal - boron - tetrahydrocarbon, a lithium hydrocarbon, a tin tetra-alkyl, or a cadmium dialkyl to reduce at least part of the metal to a valency state of 2.  Reducing compounds specified are phenyl lithium, cadmium dimethyl, tin tetrabutyl and lithium-aluminium-tetra-butyl, -hexyl, -octyl and -ethyl cyclohexyl. The other catalyst component is preferably of formula MnXm, MnRm or Mn(OR)m wherein M is the metal, R is monovalent hydrocarbon or substituted hydrocarbon, X is halogen and n and m are integers, and may be titanium dichloride, tetrachloride or tetrafluoride, zirconium or vanadium tetrachloride, molybdenum or tantalum pentachloride, tungsten hexachloride or hexafluoride, or a divalent vanadium compound.  The catalyst are said to form co-ordination complexes. Solvents or diluents used are ether, n-heptane, toluene, xylene, cyclohexane and "Decalin" (Registered Trade Mark).  Copolymers may be obtained with styrene, vinyl-toluene, -xylene or-naphthalene, a -methyl-styrene or -vinyl toluene, a - or b -halostyrene (e.g. b -bromostyrene), 2,5-dihalostyrene (e.g. 2,5-dichlorostyrene), 2,4,6-trihalostyrene and 2,6-dihalo-4-methyl vinylbenzene.  In examples, monomer is added continuously and the products are purified (catalyst decomposed) with acetone, methanol, cyclohexane, water, acetone/hydrochloric acid and/or methanol/aqueous sodium hydroxide. Grease byproducts may be extracted with benzene.  The products are solids of high density and of linear structure and may be pressed into films or moulded or extruded as insulation on wire. Specifications 536,102, 585,969, 592,335, [all in Group IV], 682,420, 694,271 and Canadian Specification 502,597 are referred to.ALSO:Catalysts used in the polymerization of ethylene (see Group IV(a)) comprise a compound of Ti, Zr, Ce, V, Nb, Ta, Cr, Mo or W, said metal being present at least in part in a valency state of 2, or the compound being associated with sufficient of an alkali metal-aluminium-tetrahydrocarbon, an alkali metal-boron-tetrahydrocarbon, a lithium hydrocarbon, a tin tetraalkyl, or a cadmium dialkyl to reduce at least part of the metal to a valency state of 2.  Reducing compounds specified are phenyl lithium, cadmium, dimethyl, tin tetrabutyl and lithium-aluminium-tetrabutyl, -hexyl, -octyl and -ethyl cyclohexenyl. The other catalyst component is preferably of formula MnXm, MnRm or Mn (OR)m wherein M is the metal, R is monovalent hydrocarbon or substituted hydrocarbon, X is halogen and n and m are integers, and may be titanium dichloride, tetrachloride or tetrafluoride, zirconium or vanadium tetrachloride, molybdenum or tantalum pentachloride, tungsten hexachloride or hexafluoride, or a divalent vanadium compound.  The catalysts are decomposed and the products purified with acetone, methanol, cyclohexane, water, acetone/hydrochloric acid and/or methanol/aqueous sodium hydroxide.  Specifications 536,102, 585,969, 592,335 [all in Group IV], 682,520 and 694,271 [both in Group IV(a)] are referred to.