Abstract: A method for polymerizing or copolymerizing .alpha.-olefin in a vapor phase condition by supplying to a reactor a catalyst composed of a solid catalyst component containing at least titanium and/or vanadium as well as magnesium and an organic aluminum compound wherein the current due to the electric charge transferred from polymer particles electrified to an electrode disposed at a position where sheet-like polymers will be produced in a reactor, as a result of contact of the polymer particles in the reactor with the electrode is determined, and the polymerization or copolymerization is carried out under such condition where the mean value of current is zero or a positive value. As a result, it becomes possible to prevent production of sheet-like polymers and to stably continue the reaction for polymerization.

Abstract: An effective catalyst carrier for use in the polymerization of olefins is provided.Said carrier comprises particles of silicon oxide or aluminum oxide satisfying the following characteristics (A) to (E):(A) An average particle diameter as measured by the sieving method is in the range of 20 to 150 .mu.m.(B) A specific surface area as measured by the BET method is in the range of 150 to 600 m.sup.2 /g.(C) The volume of pores ranging in pore radius from 18 to 1,000 Angstroms as measured by the mercury penetration method is in the range of 0.3 to 2.0 cm.sup.3 /g.(D) An apparent specific gravity as measured according to JIS K6220-6.8 is not lower than 0.32.(E) After the particles classified in the range of between 53 .mu.m and 75 .mu.m by the sieving method have been subjected to an ultrasonic disintegration treatment at 40 KHz, 35 W, for 20 minutes, the proportion of 50 .mu.m or smaller particles, i.e., degree of ultrasonic disintegration, is not more than 30%.

Abstract: In the polymerization of olefins with a vapor phase fluidized bed reactor, the improvement comprises the steps of feeding seed polymer particles and the reaction is then started after feeding an organoaluminum compound on a prescribed basis, thereby avoiding the formation of sheet-like polymer in the initial period of the reaction and the lowering of the bulk density of the product polymer.

Abstract: In the preparation of polyolefin in a vapor phase polymerization using catalysts comprising a solid catalyst component containing titanium and/or vanadium; and magnesium and an organoaluminum compound, when the reaction is stopped for a certain period of time, the restarting of reaction is possible by feeding in the first place an organoaluminum compound into the reaction system with retaining of polymer particles in the reactor.

Abstract: A process for producing polyolefin with a vapor-phase fluidized-bed reactor, wherein the reaction is started after filling the reactor with particles which contain moisture and/or molecular oxygen and can form a fluidized bed in order to prevent the formation of molten resin which is liable to occur at the start of the reaction and to attain a smooth operation of the reactor.

Abstract: According to the present invention, in a vapor phase polymerization of olefins, there is provided an efficient polyolefin manufacturing process capable of preventing the formation of a sheet-like polymer and allowing an olefin polymerization reaction to be started stably.

Abstract: A process for producing polyolefin with a vapor-phase fluidized-bed reactor, wherein the reaction is started after filling the reactor with particles which contain moisture and/or molecular oxygen and can form a fluidized bed in order to prevent the formation of molten resin which is liable to occur at the start of the reaction and to attain a smooth operation of the reactor.

Abstract: A process for feeding a powder catalyst with a gas intermittently to a high-pressure fluidized bed reactor for the vapor phase polymerization of olefin, wherein the cross section of a catalyst feed pipe is reduced midway through the pipe to thereby make continual catalyst feeding possible and prevent the formation of a lump polymer.

Abstract: A polyethylene composition which has a wide molecular weight distribution and excellent balance among melt elasticity, flow characteristics and mechanical properties, and which is suitable for use in producing large-scaled hollow plastics articles. The composition comprises a higher molecular weight ethylene polymer or copolymer and a lower molecular weight ethylene polymer or copolymer which is specified in view of the content of o-dichlorobenzene and the ratio of the area under the elution temperature-eluate volume curve between 25.degree.to 90.degree. C. to the area under said curve of 90.degree. C. and above in temperature rising elution fractionation.

Abstract: A process for feeding a powder catalyst with a gas intermittently to a high-pressure fluidized bed reactor for the vapor phase polymerization of olefin, wherein the cross section of a catalyst feed pipe is reduced midway through the pipe to thereby make continual catalyst feeding possible and prevent the formation of a lump polymer.

Abstract: A polyethylene composition which has excellent flow characteristics and mechanical properties, especially low temperature mechanical properties as well as thermal stability, elasticity and workability for molding. The polyethylene composition comprises 20 to 80 wt. % of an ethylene-.alpha.-olefin copolymer of higher molecular weight having (a) intrinsic viscosity (.eta..sub.1) of 1.2 to 9.0 dl/g, (b) density (d.sub.1) of 0.890 to 0.935 g/cm.sup.3 (c) a specific areal ratio calculated with an elution temperature-eluate volume curve in elution fractionation, and (d) a specific quantity of the content which is soluble in 25.degree. C. o-dichlorobenzene, and 80 to 20 wt. % of ethylene homopolymer or ethylene-.alpha.-olefin copolymer of lower molecular weight having (e) intrinsic viscosity (.eta..sub.2) of 0.2 to 1.6 dl/g, (f) density (d.sub.2) of 0.890 to 0.980 g/cm.sup.3 and, wherein the above (.eta..sub.1) is larger than (.eta..sub.2), and the prepared composition has an intrinsic viscosity (.eta.) of 0.

Abstract: A catalyst for polymerization of olefins is disclosed which comprises a titanium and/or vanadium compound supported on a silicon and/or aluminum oxide carrier. This carrier has peculiar characteristics including a specified proportion of highly spherical oxide particles, a selected average pore size and a specified proportion of a selected particle size range before and after ultrasonic treatment, whereby there is obtained a catalyst having increased bulk density, narrow particle size distribution and high fluidity.

Abstract: Provided is a method for vapor phase polymerization of olefins. An olefin gas is fed into a horizontal cylindrical vessel having a lower curved surface corresponding to 30 to 180 degrees of the circumference of the vessel and extending substantially the length of the vessel formed by a perforated plate having a multiplicity of holes spaced at intervals in the range of from 0.5 to 50 mm, through said plate from an olefin feed chamber mounted below and covering the plate. A polymer catalyst is fed into the horizontal cylindrical vessel through a polymerization catalyst inlet port located in a portion of the vessel other than the lower curved surface formed by the perforated plate. The olefin is reacted in the presence of a catalyst with agitation to form polymer. Unreacted olefin is removed through a discharge port located in a portion of the vessel other than the lower curved surface formed by the perforated plate.

Abstract: A horizontal agitation bed type vapor phase polymerization apparatus for olefins provided on its lower curved surface with plural cells each having an opening facing on the polymerization reaction system and further having small holes formed in its side wall portion for feeding a starting olefin gas.

Abstract: Polyolefins having a wide distribution of molecular weights are prepared in a plural stage process, by initially polymerizing the olefins in the presence of a solvent, hydrogen and a highly active Ziegler type catalyst under pressure, and beneath a gas phase containing an inert gas, to form in the first stage a polymer having a relatively high molecular weight. The polymerization reaction mixture from the first stage is continuously flowed to a second stage reactor. The second stage reactor is maintained at a relatively lower pressure, such that the flow is driven by the higher pressure in the first stage. The second stage is agitated and the polymerization reaction mixture is maintained beneath an atmosphere containing olefins and hydrogen gas. Polymers of relatively low molecular weight are formed in the second stage. The product continuously removed from the second stage contains a polymer having a wide distribution of molecular weight.

Abstract: A horizontal agitation bed type vapor phase polymerization apparatus for olefins, having a lower curved surface constructed by a perforated plate so as to allow a olefin gas to be fed uniformly throughout the reaction system through the said perforated plate.