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:
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:
Process for gas-phase polymerization carried out in two interconnected polymerization zones, to which one or more &agr;-olefins CH2═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:
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 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:
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:
Polyolefin fibers, which are suited for at least partially substituting the cellulose fibers in the manufacture of paper, are produced by a process which consists in preparing in a pressure vessel a solution of a polyolefin at a temperature higher than the boiling temperature of the solvent under normal conditions, and under autogenous pressure or a pressure greater than the autogenous pressure, in ejecting said solution under the above stated conditions into a zone of lower pressure, in allowing the ejected solution to expand at least partially in said zone, and in then hitting the at least partially expanded solution with a jet of a high-speed fluid, which is at a temperature lower than that of the solution, and has an angled direction with respect to the direction of ejection of the solution.
摘要:
Thermoplastic rubbers comprising propylene-ethylene copolymers containing from 50% to 90% by weight of propylene and showing, on X-rays examination in the unoriented state, crystallinity of the polypropylene and/or polyethylene type are disclosed.Also disclosed is a method for preparing the thermoplastic rubbers by polymerizing mixtures of propylene and ethylene in the presence of a catalyst obtained by mixing(A) a catalyst-forming component which is (a) an addition and/or substitution product of an electron-donor compound (or a Lewis base) with an Al-trialkyl compound, or (b) the addition reaction product of an electron-donor compound with an Al-alkyl compound containing two or more aluminum atoms bound to each other through an oxygen or nitrogen atom, component (A) being further characterized in that it is prepared by reacting 1.0 mole of an Al-alkyl compound with 0.1-1.0 mole of a Lewis base which is an ester of an organic or inorganic oxygenated acid, a polyamine compound, or any Lewis base other than said esters and polyamine compounds, provided that, in the latter case, component (B) of the catalyst is a complex of a halogenated titanium compound with a polyamine;and(B) a catalyst-forming component which is the product obtained by contacting an addition compound of a di-, tri-, or tetravalent titanium compound and an electron-donor compound with a carrier consisting of or comprising an anhydrous magnesium dihalide, component (B) being further characterized in that, in its X-rays powder spectrum, a halo appears in place of the most intense diffraction line characteristic of the X-rays powder spectrum of the normal, non-activated magnesium dihalide and, furthermore, in that the amount of Ti compound contained in component (B) and expressed as Ti, is less than 0.3 g. per mole of the total amount of the electron-donor compound used in preparing the catalyst and in that the molar ratio of said Ti compound to the Al-alkyl compound is comprised between 0.001 and 0.1.
摘要:
Thermoplastic rubbers comprising propylene-ethylene copolymers containing from 50% to 90% by weight of propylene and showing, on X-rays examination in the unoriented state, crystallinity of the polypropylene and/or polyethylene type are disclosed.Also disclosed is a method for preparing the thermoplastic rubbers by polymerizing mixtures of propylene and ethylene in the presence of a catalyst obtained by reacting.(A) a catalyst-forming component which is (a) an addition and/or substitution product of an electron-donor compound (or a Lewis base) with an Al-trialkyl compound, or (b) the addition reaction product of an electron-donor compound with an Al-alkyl compound containing two or more aluminum atoms bound to each other through an oxygen or nitrogen atom, component (A) being further characterized in that it is prepared by reacting 1.0 mole of a Al-alkyl compound with 0.1-1.0 mole of a Lewis base which is an ester of an organic or inorganic oxygenated acid, a polyamine compound, or any Lewis base other than said esters and polyamine compounds, provided that, in the latter case, component (R) of the catalyst is a complex of a halogenated titanium compound with a polyamine; and(B) a catalyst-forming component which is the product obtained by contacting an addition compound of a di-, tri-, or tetravalent titanium compound and an electron-donor compound with a carrier consisting of or comprising an anhydrous magnesium dihalide, component (B) being further characterized in that, in its X-rays powder spectrum, a halo appears in place of the most intense diffraction line characteristic of the X-rays powder spectrum of the normal, non-activated magnesium dihalide and, furthermore, in that the amount of Ti compound contained in component (B) and expressed as Ti, is less than 0.3 g. per mole of the total amount of the electron-donor compound used in preparing the catalyst and in that the molar ratio of said Ti compound to the Al-alkyl compound is comprised between 0.001 and 0.1.