摘要:
Process for gas-phase polymerization carried out in two interconnected polymerization zones, to which one or more .alpha.-olefins CH.sub.2 .dbd.CHR are fed in the presence of catalyst under reaction conditions and from which the polymer product is discharged. The process is characterized in that the growing polymer flows through a first polymerization zone under fast fluidization conditions, leaves said first zone and enters a second polymerization zone through which it flows in a densified form under the action of gravity, leaves said second zone and is reintroduced into the first polymerization zone, thus establishing a circulation of polymer around the two polymerization zones. The novel process allows olefins to be polymerized in the gas phase with high productivity per unit volume of the reactor without incurring the problems of the fluidized-bed technologies of the known state of the art.
摘要:
Disclosed are graft copolymers of polyolefins and a method of preparing said graft copolymers. The method comprises irradiating a mass of olefin polymer particles and thereafter treating the mass of particles with a vinyl monomer in liquid form. A nonoxidizing environment is maintained throughout the process while free radicals produced in the olefin polymer by the irradiation are present, thereby preventing degradation of the polymer. In a final step, residual free radicals are deactivated, and any unreacted monomer is removed.
摘要:
Polypropylene compositions having high impact strength at low temperatures comprising as essential components:100 parts by weight of polypropylene having an isotacticity index >90,8-25 parts by weight of an amorphous copolymeric fraction (1) of ethylene-propylene soluble in xylene at 23.degree. C., containing 20-80% by weight of ethylene,2-10 parts by weight of an ethylene-propylene crystalline copolymeric fraction (2) having a crystallinity of the polyethylene type containing 50-90% by weight of ethylene;and in which the weight ratio between the total polymerized ethylene and fraction (1) is
摘要:
Catalysts useful in the polymerization of olefins, more particularly of ethylene and mixtures thereof with higher alpha-olefins and/or diolefins, are disclosed. The new catalysts are obtained by mixing a hydride or organometallic compound of a metal belonging to Groups I to III of the Mendelyeev Periodic System with the product obtained by contacting a titanium tetrahalide with a support comprising an anhydrous magnesium or zinc halide in an active form, under particular conditions.
摘要:
Disclosed are graft copolymers of polyolefins and a method of preparing the graft copolymers. The method includes irradiating a mass of olefin polymer particles and thereafter treating the mass of particles with a vinyl monomer in liquid form. A nonoxidizing environment is maintained throughout the process while free radicals produced in the olefin polymer by the irradiation are present, thereby preventing degradation of the polymer. In a final step, residual free radicals are deactivated, and any unreacted monomer is removed.
摘要:
Supported catalysts for the high-yield polymerization of olefins to polymers which occur in spheroidal form are disclosed. The catalysts are prepared from starting components which comprise (a) organometallic compounds of metals belonging to Groups II or III of the Mendelyeev Periodic Table and (b) a product obtained by reacting a halogenated Ti compound with a Mg hydrate chloride in the form of spheroidal particles having controlled dimensions comprised between 10 and 70 microns.
摘要:
Process for the gas-phase polymerization of olefins of the formula CH2═CHR where R is hydrogen or an alkyl or aryl radical with 1 to 8 carbon atoms carried out in one or more reactors having a fluidized or mechanically agitated bed, using a catalyst obtained by reaction of a titanium halide or haloalcoholate and optionally an electron-donor compound supported on an active Mg-dihalide with an Al-trialkyl compound and optionally an electron-donor compound, comprising the steps of: a) contacting the catalyst components in the absence of polymerizable olefin or optionally in the presence of said olefin in an amount to from up to 3 g per g of solid catalyst component; b) prepolymerizing propylene or mixtures of propylene with ethylene or an alpha-olefin to form a propylene polymer having an insolubility in xylene of at least 60% by weight, in an amount of from 5 g of polymer per g of solid catalyst component to 10% by weight of the final catalyst yield; and c) polymerizing one or more CH2═CHR olefins in the gas phase in the presence of the prepolymer-catalyst system obtained in b), while maintaining in the gas phase an alkane in a molar concentration with respect to the total gases of from 20 to 90%.
摘要:
Process for the gas-phase polymerization of ethylene and ethylene mixtures with .alpha.-olefins CH.sub.2 .dbd.CHR in the presence of a high activity catalyst comprising a titanium compound containing at least one Ti-halogen bond, supported on magnesium dichloride in active form said process comprising the steps of: (a) contacting the catalyst component; (b) prepolymerizing ethylene or ethylene mixtures with .alpha.-olefins in order to produce a polymer amount of from approximately 5 g per g of solid component, up to an amount corresponding to about 10% of the final catalyst yield; (c) polymerizing ethylene or ethylene mixtures with .alpha.-olefins in the gas-phase, in the presence of the prepolymer-catalyst system obtained in (b), while maintaining in the gas phase a molar concentration concentration of the alkane comprised between 20 and 90% with respect to the total gases.
摘要:
There are disclosed components of catalysts for polymerizing ethylene and mixtures of ethylene with alpha-olefins comprising the reaction product of (A) a magnesium compound, such as Mg-chloride, Mg-alcoholate or a Grignard compound, with (B) a titanium, vanadium or zirconium compound having at least two metal-oxygen bonds, such as a tetra-alcoholate, and with (C) a halogenated compound of metals of B, such as Ti tetrachloride.According to an aspect of the invention, the reaction product (A)+(B), before being reacted with (C), is treated with a silicum compound having a halogenating and/or reducing action.The catalysts according to the invention are suitable for obtaining ethylene polymers having a broad distribution of molecular weights.
摘要:
There are disclosed highly active supported catalysts for the polymerization of olefins to polymers in the form of spheroidal particles which neither break nor cake when subjected to compression. The supported catalysts are prepared by mixingA. a catalyst-forming component which is an organometallic compound of a metal belonging to Group II or III of the Mendelyeev Periodic TableWithB. a supported catalyst-forming component which is the product consisting of a carrier comprising an anhydrous Mg halide and of a halogenated Ti compound chemically combined with the carrier or dispersed on the same, said product being in the form of spherical or spheroidal particles of a size comprised between 1 and 350 microns and having characteristics as set forth in detail hereinbelow.