Patent GB-804641-A (GB)
Title: Improvements in or relating to polymers and catalytic production thereof
IPC: C08F2/00
Filed: 1955-01-20
Abstract: Catalysts for the polymerization of olefines, are prepared by impregnating a porous solid support of zirconia or thoria with a solution of chromium oxide or a compound convertible to the oxide by calcination.  The catalyst is activated by contacting with dry air at from 750 DEG  to 1500 DEG  F. to obtain a composite containing from 0.1 to 10 per cent by weight of chromium as oxide.  Chromium trioxide, nitrate, acetate, chloride, and sulphate and ammonium chromate and dichromate are referred to, and some of the chromium in the composite must be in the hexavalent state, preferably at least 0.1 per cent of the composite.  Pretreatment of the catalyst base by a fluoride, alone or in aqueous or non-aqueous solution, and heating, e.g. from 300 DEG  to 1100 DEG  F., or activation of the composite in the upper part of the temperature range effects the molecular weight and other properties of the polymer product. The catalyst may be regenerated by washing with, for example, pentane or iso-octane at 300 DEG  to 400 DEG  F. under pressure and burning off the polymer at 900 DEG  to 1100 DEG  F.  Silica and alumina may be present in the support and additional oxides such as copper, calcium, zinc, magnesium, barium and nickel oxides, tin, caesium, and titanium dioxides, manganese, cobalt, iron, antimony, molybdenum, boron and tungsten trioxides, and vanadium pentoxide, may be used as promoters. Water, oxygen, carbon monoxide and aromatic compounds which act as poisons should be removed.  Specifications 790,196 and 804,642 are referred to.ALSO:Olefines are polymerized at temperatures up to approximately 450 DEG  F., in the presence of a catalyst comprising chromium oxide, at least a portion of the chromium being in the hexavalent form, and at least one oxide of the group zirconia and thoria. Ethylene, propylene, 1-butene, 1-pentene, 1-hexene, butadiene, isoprene and conjugated di-olefines substituted with methyl and ethyl groups are mentioned.  1-Olefines having a maximum of 8 carbon atoms and no branching nearer the double bond than the 4-position yield tacky and solid polymers.  Diluents such as propane, isobutane, normal pentane, isopentane, iso-octane, cyclohexane and methylcyclohexane may be present and polymerization effected at a pressure e.g. 100 to 700 p.s.i.g. sufficient to maintain the diluent in the liquid state at a temperature within the range 150 DEG  to 450 DEG  F., preferably 275 DEG  to 375 DEG  F. for ethylene and 150 DEG to 250 DEG  F. for propylene and higher olefines.  The catalysts may be prepared as described in Specification 790,196 (see Group III) and may be used in a fixed or moving bed as a suspension and the catalyst regenerated. Polymers of differing average molecular weights or of increased molecular weight and flexibility may be obtained respectively by using catalysts activated at various temperatures or pretreated preferably before the addition of chromium oxide, with a fluoride. Water, oxygen, carbon monoxide and aromatic compounds poison the catalyst and should be removed from the feed.  In examples ethylene is polymerized in the presence of chromium oxide deposited on supports of thoria or zirconia alone or thoria with 90 per cent silica or alumina, or zirconia or thoria promoted with 10 per cent of copper, calcium, zinc, magnesium, barium and nickel oxides, tin, cerium and titanium dioxides, manganese, cobalt, iron, antimony, molybdenum, boron and tungsten trioxides, and vanadium pentoxide and zirconia with 10 per cent thoria, at a temperature of up to 330 DEG F. and a pressure of at least 450 p.s.i.g. to give a product which may be extracted with pentane to yield a solid polymer, and the pentane-soluble material extracted with methyl isobutyl ketone to obtain a tacky polymer; or fractionated to produce an overhead fraction, and a bottoms fraction from which a tacky polymer is extracted by methyl isobutyl ketone leaving a solid polymer. Copolymers of ethylene with propylene or 1-butene or 1,3-butadiene, and propylene with 1-butene or a pentene are mentioned and in particular a propylene-ethylene feed mixture containing from 10 to 45 per cent propylene polymerized at from 240 DEG  to 320 DEG  F. yields copolymers capable of being extruded as films which are particularly resistant to moisturevapour penetration and have high transverse tear strength.  Polymers or copolymers prepared by this method are characterized by their unsaturation being predominantly of the transinternal and/or terminal vinyl type.  Polyethylene of this type has an average molecular weight of at least 5000, a melting point of 240 DEG  to 260 DEG  F. and a density of 0.92 to 0.96. Polypropylene with an average molecular weight of 200 to 50,000 may comprise an oil of boiling point about 400 DEG  F., a tacky fraction boiling above 900 DEG  F. soluble in pentane and a solid polymer of M.P. 240 DEG to 300 DEG  F., a density of 0.90 to 0.95 and a molecular weight of at least 5000 and similarly polybutylene from 1-butene comprises a liquid fraction boiling in range 400 DEG  to 900 DEG  F., a tacky fraction boiling above 900 DEG  F. and a solid fraction. The tacky products may be used in pressure-sensitive adhesive tapes, sealing compounds, laminated and tracing paper, hydraulic fluids, electrical capacitors, surface coatings and rubber extenders or blended with lubricating oils as viscosity index improvers, and the solid products may be moulded for example as bottles or extruded as films or pipes. Specification 804,642 also is referred to.