Abstract: A process to produce high melt flow propylene polymer comprises polymerizing propylene in the presence of a titanium-containing, magnesium-containing, high activity catalyst and an aluminum alkyl cocatalyst in a gas phase system which uses condensed liquid to control temperature wherein the external catalyst modifier is a tetraalkylorthosilicate, preferably tetraethylorthosilicate, at process conditions of temperature, hydrogen concentration, and Si/Mg, Al/Mg and Al/Si atomic ratios, to produce a high melt flow propylene polymer at high yield.

Abstract: The present invention provides methods for the homopolymerization and/or copolymerization of olefins. In preferred methods of the invention the polymerizable olefins have the general formula of CH.sub.2 .dbd.CR.sub.1 R.sub.2, wherein R.sub.1 and R.sub.2 are the same or different, and are hydrogen or a C.sub.1 -C.sub.10 alkyl. In particularly preferred embodiments, the methods further comprise contacting the polymerizable olefin with a procatalyst and a co-catalyst. In other embodiments, the methods further involve the use of an electron donor.

Abstract: A process for preparing high density polyethylene in the gas phase comprising contacting a mixture comprising ethylene and one or more alpha-olefins with the supported reaction product of a bis-hydrocarbylsilyl chromate and a hydrocarbylaluminum compound or a hydrocarbyl boron compound in a fluidized bed reactor having a recycle gas line, under particularly defined polymerization conditions, including, but not limited to, the following provisos:(i) oxygen and/or another catalyst poison is introduced into the reactor in the range of about 0.005 to about 0.5 part by volume of catalyst poison per million parts by volume of ethylene; and(ii) a relatively low boiling inert hydrocarbon is introduced into the recycle gas line in an amount sufficient to raise the dew point of the recycle gas, which is comprised of alpha-olefins and other reactor gases, and the recycle gas is partially condensed and recycled to the reactor where it promotes cooling by evaporation.

Abstract: A solution polymerization system for polymerizing a olefin monomer by reacting the monomer with catalyst and solvent has been invented. The system in one aspect including a flow loop with a product polymer outlet, the flow loop forming a recycling reactor, a catalyst inlet on the flow loop through which catalyst and solvent flow into the flow loop, a monomer inlet on the flow loop through which monomer and solvent flow into the flow loop and, with the catalyst, form a reactant materials stream, a first heat exchanger on the flow loop for receiving the reactant materials stream and any formed polymer and for removing heat of reaction or polymerization from the flow loop, and pump apparatus for pumping the reactant materials stream and formed polymer in the flow loop and from the first heat exchanger to the product polymer outlet.

Abstract: Process for the in situ polymerization of ethylene with C.sub.3 -C.sub.10 alpha-olefins in suspension of liquid monomer in the presence of a catalyst containing Vanadium obtained by the precipitation, in an atmosphere of ethylene or alpha-olefins, of:a) a compound of Vanadium in the oxidation state of 3 to 5, withb) a basically hydrocarbon solution of a compound selected from those having general formula R.sub.n AlX.sub.m wherein R is a C.sub.1 -C.sub.20 alkyl radical, X is a halogen, m+n=3, n is an integer from 0 to 2.

Abstract: A catalyst formed by the reaction of a magnesium alkoxide dispersion having a particle size of from 100 to 3000 nm with a compound of a metal selected from the group comprising titanium, zirconium, vanadium and chromium and then with a chlorine-containing organoaluminum compound possesses a very good hydrogen responsiveness and a high activity even in the presence of molecular-weight regulators such as hydrogen. The catalyst is therefore outstandingly suitable for the production of low molecular-weight polyolefins. The catalyst makes possible the production of waxes having a reduced residual ash content. The large particle diameter and the low fines content of the polymer powder produced by suspension polymerization with this catalyst enables easy removal of the suspension medium and drying. The catalyst is furthermore advantageously used in solution polymerization and, because of the large particle diameter, in gas phase polymerization for producing low molecular-weight poly-1-olefins.

Abstract: A process for the gas phase polymerization of olefins. In this process a transition metal-containing solid catalyst component is introduced into a cylindrical section of a vertically disposed reactor in a first stream. A second stream, comprising an organometallic cocatalyst component is simultaneously separately introduced into the said cylindrical section of a vertically disposed reactor at a distance from the point of introduction of the first stream of no more than about 20% of the inside diameter of the tubular reactor.

Abstract: The present invention provides an ethylene copolymer comprising constituent units (a) derived from ethylene and constituent units (b) derived from an .alpha.-olefin having 3 to 20 carbon atoms, the ethylene copolymer being characterized in that(A) the ethylene copolymer has a density (d) of 0.86 to 0.95 g/cm.sup.3 ;(B) the ethylene copolymer has a MFR of 0.001 to 50 g/10 min as measured at a temperature of 190.degree. C. and a load of 2.16 kg;(C) the melt tension (MT) and MFR of the ethylene copolymer satisfy the relationlog MT>-0.66log MFR+0.6; and(D) the temperature (T) at which the exothermic curve of the ethylene copolymer measured by a differential scanning calorimeter (DSC) shows the highest peak and the density (d) satisfy the relationT<400d-250.

Abstract: A process for producing a styrenic polymer having the syndiotactic configuration which process comprises a plurality of polymerization stages, at least one polymerization stage selected as desired from the plurality of polymerization stages being a polymerization stage in which hydrogen is introduced; in accordance with the present invention, efficient control of molecular weight and molecular weight distribution is enabled. By increasing activity of the polymerization catalyst, the amount of the catalyst and the amount of residual metals can be decreased, and the cost of production can be decreased.

Abstract: Interpolymer of a) a mono-olefin selected from the group consisting of .alpha.-olefins and cyclic olefins, and b) a non-conjugated polyene having at least 7 carbon atoms and having two readily polymerizable double bonds, having an improved melt tension, improved processability, or a combination of both, a process of preparing such interpolymers, composition comprising such interpolymers and one or more further natural or synthetic polymers or one or more additives or adjuvants, as well as articles obtained by subjecting such interpolymers to melt processing conditions.

Abstract: The present invention provides a process for control of desired properties in the polymer product. The catalyst system used in the process includes a supported metallocene catalyst precursor in combination with an oxyorganoaluminum. The process can be applied to the co-polymerization of propylene and ethylene. The randomness of the ethylene incorporation of the co-polymer product is increased as the amount of ethylene in the feed is increased. The amount of ethylene in the feed is up to 6 wt. % with a resulting amount of ethylene incorporated into the copolymer product up to 4 mole %.

Abstract: Metallocenes containing aryl-substituted indenyl derivatives as ligands, process for their preparation, and their use as catalysts.A very effective catalyst system for the polymerization or copolymerization of olefins comprises a cocatalyst, preferably an aluminoxane or a supported aluminoxane, and a metallocene of the formula I ##STR1## in which, in the preferred form, M.sup.1 is Zr or Hf, R.sup.1 and R.sup.2 are halogen or alkyl, R.sup.3 is alkyl, R.sup.4 to R.sup.12 are alkyl or hydrogen and R.sup.13 is a (substituted) alkylene or heteroatom bridge.The metallocenes, in particular the zirconocenes, produce polymers of very high molecular weight, in the case of prochiral monomers polymers of very high molecular weight, very high stereotacticity and very high melting point, at high catalyst activities in the industrially particularly interesting temperature range between 50.degree. and 80.degree. C. In addition, reactor deposits are avoided by means of supported catalyst systems.

Abstract: A colorable resin particle having an outer shell of a non-sticky polymer and an inner core of a sticky polymer produced in a gas phase fluidized bed reactor at or above the sticking temperature of the sticky polymer using a non-sticky prepolymerized catalyst and processes for producing the colorable resin and the non-sticky prepolymerized catalyst.

Abstract: Process with two or more steps for the preparation in suspension of mixtures of ethylene-propylene (EPM) elastomer homopolymers or ethylene-propylene-diene (EPDM) elastomer terpolymers in the presence of a catalytic system essentially consisting of a compound of Vanadium and a cocatalyst essentially consisting of an Aluminum alkyl and in the presence of an activator, the above process being characterized in that:a) in the first step a first polymerization of the monomers is carried out in the presence of the Vanadium based catalyst;b) in the second or subsequent steps further polymerizable monomers and activator are added to the suspension of the polymer obtained in step (a).

Abstract: A syndiotactic polyolefin is obtained in a high yield by polymerization or copolymerization of an olefin of the formula R.sup.a --CH.dbd.CH--R.sup.b in the presence of a catalyst consisting of a metallocene of the formula I ##STR1## in which M.sup.1 is titanium, zirconium, vanadium, niobium or tantalum, and an aluminoxane. This polyolefin has a very high molecular weight, a very narrow molecular weight distribution and a very high syndiotactic index. Shaped articles produced from the polymer are distinguished by a high transparency, flexibility, tear resistance and an excellent surface gloss.

Abstract: Polymerization process to obtain elastomeric copolymers or terpolymers based on ethylene for cold flow improver (CFI) having a viscosimetric average molecular weight ranging between 600 and 16,000.a) The process includes polymerizing monomers in suspension in the presence of an alpha-olefin liquid under reaction conditions, in the presence of an amount of solvent from about 5 to 30% by volume of the reactor volume in the presence of a polymerization catalyst able to give the X.sub.2 and/or X.sub.4 parameters, lower less than or equal to 0.02, X.sub.2 and X.sub.4 representing the fraction of uninterrupted methylenic sequences of 2 and 4 methylenic groups between two successive methyl or methylene groups respectively in the polymeric chain, as compared with the uninterrupted total sequences of methylene groups determined by .sup.

Abstract: The present invention provides a process for preparing polyolefins having a multimodal or at least bimodal molecular weight distribution by contacting in a reaction mixture under polymerization conditions at least one olefin and a catalyst system comprising a supported catalyst-component comprising an alumoxane and at least two metallocenes containing the same transition metal and selected from mono, di, and tri-cyclopentadienyls and substituted cyclopentadienyls of a transition metal and wherein at least one of the metallocenes is bridged and at least one of the metallocenes is unbridged.

Abstract: Catalyst compositions comprising metallocene complexes having polymerisable may be used for the preparation of polyolefins.The catalyst compositions may be in the form of polymers comprising the metallocene complex and may be suitably supported on inorganic supports. Polymers having a broad range of density and melt indices as well as low hexane extractables and excellent powder morphology and flowability may be obtained by use of the catalyst compositions. Preferred metallocene complexes are zirconium complexes in which the polymerisable group is vinyl.

Abstract: The invention relates to a supported, prepolymerized metallocene catalyst system as well as its production and use in olefin polymerization. The method for producing the prepolymerized catalyst system involves prepolymerizing a metallocene catalyst system containing a volume of solution that is the equivalent of or less than the total pore volume of the supported catalyst system.

Abstract: In gas phase polymerizations and copolymerizations of ethylene, temperature controls the molecular weight, expressed as MI (wherein MI is measured according to ASTM D-1238 Condition E), of the resin product. Increase in polymerization temperature produces decrease in MI; whereas, decrease in polymerization temperature produces increase in MI.

Abstract: A catalyst system comprising a bridged fluorenyl-containing metallocene, an unbridged metallocene, and a suitable cocatalyst and the use of such catalyst systems to produce olefin polymers. Also novel olefin polymers produced by those processes.

Abstract: A process for polymerizing olefins, diolefins and/or acetylenically unsaturated monomers using novel catalyst compositions comprising titanium or zirconium complexes containing one and only one cyclic delocalized, anionic, .pi.-bonded group wherein the metal is in the +2 formal oxidation state and having a bridged ligand structure, also referred to as constrained geometry complexes, and an activating cocatalyst.

Abstract: Disclosed are unsaturated .alpha.-olefin/.alpha., .omega.-diene copolymers, and a method of preparation thereof. The copolymers are generally crystalline, free of gel and cross-links, and contain unsaturated side chains and long chain branching. The copolymers contain up to 5 mole percent diene incorporated therein, and may be prepared by copolymerization using a solid-phase, insoluble coordination catalyst, without a solvent, and below the crystalline melting point of the copolymer.

Abstract: A process for the production of a homogeneous polyethylene comprising contacting a mixture comprising ethylene, one or more alpha-olefins, and one or more unconjugated dienes, under polymerization conditions, with a catalyst system comprising:(a) a catalyst precursor, in independent or prepolymer form, consisting of vanadium (acetylacetonate).sub.3 ;(b) optionally, a support for said precursor;(c) a cocatalyst consisting of an alkylaluminum halide having the formula AlR.sub.(3-a) X.sub.a wherein each R is independently alkyl having 1 to 14 carbon atoms; each X is independently chlorine, bromine, or iodine; and a is 1 or 2; and(d) a promoter, which is a chlorinated ester having at least 2 chlorine atoms; a saturated or unsaturated aliphatic halocarbon having at least 3 carbon atoms and at least 6 halogen atoms; or a haloalkyl substituted aromatic hydrocarbon wherein the haloalkyl substituent has at least 3 halogen atoms.

Abstract: A process for preparing syndiotactic polymers of vinylaromatic monomers comprising contacting one or more vinylaromatic monomers with a catalyst system comprising a pentamethylcyclopentadienyltitanium based metal complex capable of preparing syndiotactic vinylaromatic polymers under coordination polymerization conditions in the presence of hydrogen gas at a hydrogen partial pressure from 10 to 45 kPa and maintaining said partial pressure of hydrogen continuously throughout the polymerization.

Abstract: There is disclosed a process for producing a styrenic polymer having a syndiotactic configuration which comprises polymerizing a styrenic monomer containing hydrogen dissolved therein at a hydrogen partial pressure of at most 1 kg/cm.sup.2 G by the use of a polymerization catalyst comprising an (a) transition metal compound and a (b) coordination complex compound composed of a cation and an anion in which a plurality of radicals are bonded to a metal, or an aluminoxane and, when necessary, a (c) alkylating agent. The above process is capable of modifying the molecular weight of the objective SPS, lowering its molecular weight without expanding the molecular weight distribution, and decreasing the required quantity of the catalyst and the residual quantities of metals in the resultant SPS, whereby the production cost of the objective SPS is considerably curtailed.

Abstract: A polymerization catalyst system is provided comprising a catalyst and a cocatalyst, wherein the catalyst comprises a chromium compound and a transition metal compound, wherein said chromium compound is a cyclopentadienyl compound, wherein the transition metal compound is a titanium hydrocarbyloxide, and wherein said cocatalyst is an organoaluminum-halide compound. Other aspects of the invention provide a process for preparing the catalyst described above, a polymerization process employing the catalyst, and the polymer produced.

Abstract: A catalyst system for the polymerization of alpha-olefins comprising a chromium-containing catalyst and an yttrium-containing catalyst wherein the yttrium-containing catalyst is represented by the formula (Cp.sub.2 YX.sub.x).sub.y.M.sub.z L.sub.n, wherein Cp is cyclopentadienyl or cyclopentadienyl substituted with alkyl or alkyl silyl radical or radicals, X is a halogen, M is an alkali metal, L is a suitable electron donor ligand, x is 1 or 2, y is 1 or 2, z is 0 or 1, and n is a number corresponding to the value needed to form a stable complex, with the proviso that when y is 2, z and n are 0 is provided. Also disclosed is a polymerization process employing such a catalyst system, and novel olefin polymers. Polymers thus produced exhibit high bulk density and a broad molecular weight distribution.

Abstract: The invention relates to a method for homo- or copolymerizing ethene in the presence of a Ziegler-Natta or other catalyst and a possible comonomer and hydrogen for preparing a homo- or copolymer of ethene in particle form in propane. In accordance with the invention, the polymerization is performed in a loop reactor under such supercritical conditions where the temperature is higher than the critical temperature of the mixture formed by ethene, propane and a possible hydrogen and a comonomer, but lower than the melting temperature of the ethene polymer forming in the polymerization, and the pressure is higher than the critical pressure of said mixture.

Abstract: Process for the preparation of elastomeric copolymers of ethylene, wherein ethylene is copolymerized with an .alpha.-olefin, and possibly with a diene as termonomer, in the presence of a Ziegler-Natta catalyst including a solid component of catalyst based on titanium and aluminium, supported on magnesium chloride and obtained, in accordance with a special procedure, in the form of a spherical granular solid. This process produces elastomeric copolymers having a low crystallinity even with a high content of linked ethylene.

Abstract: A process for the production of EPDM comprising reacting ethylene, propylene, ethylidene norbornene, and hydrogen, in the gas phase, in a fluidized bed, under polymerization conditions, in the presence of a catalyst system comprising:(a) the reaction product of a vanadium compound and a electron donor;(b) at least one modifier having the formula BX.sub.3 or AlR.sub.(3-a) X.sub.a wherein each R is alkyl or aryl and is alike or different; each X is independently chlorine, bromine, or iodine; and a is 0, 1, or 2,wherein components (a) and (b) are impregnated into an inorganic support;(c) a halocarbon promoter; and(d) a hydrocarbyl aluminum cocatalyst with the following proviso:(i) the partial pressure of ethylene is in the range of about 25 to about 200 psi;(ii) the molar ratio of propylene to ethylene is in the range of about 0.2:1 to about 2:1;(iii) the molar ratio of hydrogen to ethylene is in the range of about 0.0001:1 to about 0.01:1; and(iv) the amount of ethylidene norbornene is about 1.

Abstract: Polypropylene based resins and compositions comprising the resin having extremely high stiffness, heat resistance and impact strength, with these properties being well-balanced, are provided. The polypropylene based resins are characterized by comprising:(1) a propylene polymer having a content of alpha-olefin other than propylene of not more than 4 mole percent, and the following properties (2), (3) and (4):(2) a pentad fraction (mmmm fraction) measured by .sup.13 C-NMR of not less than 96.0 percent,(3) a main elution fraction peak position of not less than 118.0.degree. C. and a peak half value width of less than 4.0, these values being measured by the temperature raising separation method, and(4) an intrinsic viscosity of not less than 0.5 dl/g, but not more than 5.0 dl/g; and,(5) a rubber content measured by pulse NMR of more than 25 percent.

Abstract: The invention concerns a multi-stage process for producing polyethylene having a bimodal and/or broad molecular weight distribution in the presence of an ethylene polymerizing catalyst system in a multistep reaction sequence, in which the first reaction step is a liquid phase polymerization step and the second reaction step is formed by one or more gas-phase polymerization steps. According to the process of the invention in the first reaction step ethylene is polymerized in a loop reactor (10) in an inert low-boiling hydrocarbon medium the residence time being at least 10 minutes, reaction mixture is discharged from the loop reactor (10) and at least a substantial part of the inert hydrocarbon mixture is separated and the polymer is transferred into one or more gas-phase reactors (30), where the polymerization is completed in the presence of ethylene and optionally hydrogen and a comonomer.

Abstract: An ethylene polymerization catalyst system is provided. This catalyst system is produced by the process comprising forming an activated and reduced composition that is substantially free of titania and that comprises a fluorine compound, a chromium compound, and a catalyst support that consists essentially of silica.An ethylene polymerization process is provided. This process uses the ethylene polymerization catalyst system above. This catalyst system is contacted with ethylene, in the presence of hydrogen and trialkylaluminum, under polymerization conditions, to produce a polyethylene resin.

Abstract: A process for the polymerization of olefins in the presence of hydrogen comprising contacting the olefin, a cyclopentadienyl compound and a catalyst comprising a transition metal compound at polymerization conditions.

Abstract: A process for polymerizing olefins is disclosed which makes use of a catalyst comprising a cyclopentadienyl yttrium halide alkali metal electron donor complex in combination with a cocatalyst comprising an alkali or alkaline earth metal alkyl. Preferred embodiments include the use of hydrogen during the polymerization.

Abstract: Styrene homo-or-co- polymers, the stereoregularity of which is mainly syndiotactic are disclosed, having repeating unit or two or more different repeating units defined by a general formula (I): ##STR1## wherein each R may be the same or different. And a method of preparation of syndiotactic copolymers wherein there are two different repeating units represented by formula (I); wherein the polymerization is carried out with a catalyst comprising (a) a titanium compound and (b) a contact product of an organoaluminum compound and a condensing agent such as water.

Abstract: The present invention relates to a process for (co-)polymerizing ethylene in a gaseous phase, by means of a fluidized and/or mechanically stirred bed reactor, with the help of a catalyst comprising a chromium oxide and a titanium compound, supported on a refractory oxide and activated by a heat treatment. The process is characterized in that the catalyst is introduced into the reactor in the form of a dry powder consisting of particles free from prepolymer and the (co-)polymerization is carried out in the presence of an organoaluminium compound. The (co-)polymer thus obtained has substantially low catalyst residues, and an improved stress cracking resistance.

Abstract: A copolymer of trans-1,4-hexadiene and propylene, and a method for its preparation. The copolymer is isotactic, essentially free of cis-1,4-hexadiene, and contains from 0.01 to 5 mole percent 1,4-hexadiene. The copolymer is radiation-stabilized against molecular weight degradation, and cross-links to form gel upon exposure to radiation. The copolymer is prepared by contacting a mixture of propylene and 1,4-hexadiene essentially free of cis-1,4-hexadiene with a coordination catlyst, e.g. Ziegler-Natta catalyst, under copolymerization conditions. Hydrogen is used to moderate the molecular weight of the copolymer and enhance the catalyst activity.

Abstract: A process for the simultaneous trimerization of ethylene and the copolymerization of the trimer with ethylene comprising continuously contacting ethylene, the 1-hexene which is formed, and, optionally, hydrogen in a reaction zone, under trimerization and polymerization conditions, with the supported reaction product of one or more bis-triarylsilyl chromates and one or more trihydrocarbylaluminum compounds wherein the atomic ratio of aluminum to chromium is at least about 3 to 1.

Abstract: A process for polymerizing olefins is disclosed which makes use of a catalyst comprising a cyclopentadienyl lanthanide halide alkali metal ether complex in combination with a cocatalyst comprising an alkali or alkaline earth metal alkyl. Preferred embodiments include the use of hydrogen during the polymerization or the use of an organoaluminum hydride as an additional cocatalyst.

Abstract: Disclosed herein is a method for controlling the molecular weight of a propylene homo- or co-polymer at a constant level upon subjecting propylene alone or a mixture of propylene and another .alpha.-olefin copolymerizable with propylene as a monomer or monomer mixture to bulk polymerization in the presence of hydrogen as a molecular weight modifier in a reaction tank equipped with a reflux condenser.

Abstract: Ethylene copolymers having a very low molecular weight are continuously prepared in a fluidized bed in the presence of reduced concentrations of hydrogen, at improved catalyst activity and polymer productivity, by effecting polymerization in the presence of a dialkylzinc compound.

Abstract: A process for polymerizing olefins using a catalyst comprising an organolanthanide compound is disclosed wherein the active lifetime of the catalyst is increased by the employment of hydrogen during the polymerization.

Abstract: Ethylene homopolymers or copolymers having a very low molecular weight are continuously prepared in a fluidized bed in the presence of high concentrations of hydrogen, while maintaining high catalyst activity, by means of a vanadium-based catalyst.

Abstract: A process for production of styrene polymers is disclosed, comprising polymerizing styrene monomers by the use of a catalyst comprising (a) a titanium compound and (b) a contact product of an organoaluminum compound and a condensing agent, and further in the presence of hydrogen. The styrene polymers produced by the present process have a stereo structure that substituent groups are mainly in the syndiotactic configuration. Thus the styrene polymers have high heat resistance and high solvent resistance as compared with atactic polystyrene commonly used and are useful as materials for production of articles for which high heat resistance and high solvent resistance are required.

Abstract: A highly crystalline polypropylene is provided having:(A) (i) a melt flow rate (MFR) in the range of 0.1-200 g/10 minutes 230.degree. C. and (ii) an absorbance ratio determined by infrared absorption spectroscopy, IR-.rho., of wave-number 997 cm.sup.-1, A.sub.997, to wave-number 973 cm.sup.-1, A.sub.973, which satisfies the equation:IR-.tau..gtoreq.0.0203 log MFR+0.950; and(B) (i) an IR-.tau. value of at least 0.97 of a component deposited initially in an amount of 2 to 3% by weight from a dilute, slowly cooled and stirred xylene solution of the polypropylene and (ii) a ratio of the weight average molecular weight of the deposited component (M.sub.w1) to that of the polypropylene (M.sub.w0), M.sub.w1 /M.sub.w0, of at least 3.

Abstract: Continuous processes for producing high melting and viscoelasting polypropylene or ethylene-propylene copolymer are provided.These processes are characterized by (1) using two or more polymerizers connected in series, (2) supplying the whole amount of a catalyst and a molecular weight regulator (hydrogen) in the first tank and (3) a degasification amount of each tank in the second and subsequent tanks being 0.5 to 10 V.sub.1 /Hr (wherein V.sub.1 is a volume of the tank) calculated at 0.degree. C., and 0 Kg/cm.sup.2 G. In the process for producing the copolymer, (4) monomers having an ethylene content of 5 wt % or less are supplied in the first step. According to the processes of the present invention, polymers having a broad molecular weight distribution and good fluidity upon extrusion molding can be obtained and operational control in production is simply made.

Abstract: A process for producing a polyolefin having a multimodal molecular weight distribution wherein the polymerization is conducted in the presence of hydrogen and a catalyst system containing aluminoxane and at least two different metallocenes each having different olefin polymerization termination rate constants in the presence of hydrogen, and the process of producing the catalyst system.

Abstract: A two-stage polymerization process using a modified supported catalyst gives ethylene polymers with very good processability and excellent finished component properties. The supported catalyst used is formed by reaction of a magnesium alcoholate with a titanium-IV compound in suspension and subsequent reaction with a halogen-containing organoaluminum compound and activation of the solid thus obtained by an aluminum trialkyl or aluminum isoprenyl.