Abstract: Novel supported, titanized chromium catalysts can be used for the homopolymerization of ethylene and the copolymerization of ethylene with &agr;-olefins.

Abstract: High melt index polyolefins have been obtained with chromium silica catalysts under conventional polymerization conditions without the use of titanium or other additives. The useful chromium silica catalysts have a pore volume in the range of 1.9-2.9 cc/g and a narrow pore size distribution. The silica is a silica gel preferably obtained from a low solids, rapid gelation process.

Abstract: Methods of making supported chromium catalyst systems and processes of polymerizing ethylene using the supported chromium catalyst systems are disclosed. A method of forming a catalyst system in a polymerization reactor includes contacting a supported chromium catalyst and a metal alkyl cocatalyst by cofeeding the catalyst and cocatalyst to the reactor or feeding the catalyst and cocatalyst separately to the reactor, to form a catalyst system. The catalyst and cocatalyst are not pre-contacted prior to the feeding or cofeeding step. The catalyst system can be contacted with ethylene and optional alpha-olefin comonomer to form polyethylene.

Abstract: Polymerization processes are disclosed for producing polyethylene having a target density and improved environmental stress resistance. Ethylene and optionally one or more &agr;-olefin comonomers, supported chromium catalyst, and metal alkyl cocatalyst are contacted to produce polyethylene. The density of the polyethylene is determined, and the concentration of cocatalyst is adjusted in response to a deviation between the density of the polyethylene and the target density. The catalyst and cocatalyst can be fed separately into the reactor, or can be co-fed, eliminating the need to pre-contact the catalyst and cocatalyst prior to introducing them into the reactor.

Abstract: Polymerization processes for ethylene and at least one mono-1-olefin comonomer having from about three to eight carbon atoms per molecule in the presence of a twice-aged catalyst system comprising chromium supported on a silica-titania support and a trialkylboron compound is provided. Novel ethylene copolymers also are produced.

Abstract: A continuous vapor-phase fluidized-bed process for the preparation of ethylene homopolymers and copolymers having a density of from 0.87 to 0.97 g/cm3 in which ethylene or mixtures of ethylene and C3-C8 a-monoolefins are (co)polymerized in the presence of a supported chromium catalyst in the polymerization zone of a vapor-phase fluidized-bed reactor under pressures ranging from 1 to 100 bar and at temperatures ranging from 30° to 125° C.

Abstract: A process for preventing polymeragglomeration and for controlling the density of copolymer produced by an alpha-olefin copolymerization process in a polymerization reactor, wherein the ratio of the flow rates of introduction of the comonomer(s) to the monomer is kept constant.

Abstract: The invention relates to a catalyst support and to a method for the production of the catalyst support comprising the following steps: a) production of a silicic acid hydrogel having a solids content of from 10 to 25% by weight (calculated as SiO2) whose particles are substantially spherical, b) extraction of the hydrogel particles with an alcohol until at least 60% of the water present in the hydrogel has been removed, c) drying of the resultant hydrogel until the residual alcohol content is less than 10% by weight (xerogel formation) at temperatures of ≧160° C. at atmospheric pressure using an inert entraining gas, d) setting of the desired particle size of the resultant xerogel, in which the hydrogel particles have a particle size of ≧8 mm before the extraction, and to a catalyst and to a method for the production of the catalyst by loading the catalyst support with a chromium compound. The invention also relates to a method for the production of polyolefins using the catalyst.

Abstract: The invention relates to a method for producing an ethylene polymer, comprising performing polymerization of ethylene in co-presence of hydrogen using a trialkylaluminum compound-carried chromium catalyst, wherein the chromium catalyst is obtained by calcination-activating a chromium compound that is carried on an inorganic oxide carrier in a non-reducing atmosphere to convert chromium atoms in the chromium compound into hexavalent chromium atoms for at least a portion thereof, and treating with a trialkylaluminum compound in an inert hydrocarbon solvent to carry thereon and removing to dry the solvent so that the chromium atoms are not over-reduced by the trialkylaluminum compound, and to an ethylene polymer suitable for blow molded articles obtained by the production method. The ethylene polymer of the invention have improved environment stress crack resistance (ESCR) and impact resistance in a good balance and are suitable for molded blow articles, in particular large size blow molded articles.

Abstract: A process comprising polymerizing ethylene, or polymerizing ethylene and at least one other olefin, to produce a polymer is provided.

Abstract: A process for the gas-phase (co-)polymerization of olefins in a fluidized bed reactor using a chromium oxide catalyst. The polymerization is performed in the presence of a process aid additive.

Abstract: Described is the use of nanoscale metal oxide particles as catalysts for the thermal and/or photochemical polymerization of species having at least one polymerizable carbon-carbon multiple bond and/or at least one carbon containing ring capable of undergoing a ring opening polymerization.

Abstract: Ths invention provides a process for the preparation of a polyethylene, in particular an HDPE suitable for blow moulding of HIC, which comprises polymerizing ethylene and, optionally an ethylenically unsaturated comonomer copolymerizable therewith, in the presence of a catalyst comprising a first silica-supported chromium catalyst having a pore volume of at least 2 mL/g, a surface area of at least 350 m2/g and a chromium content of 0.1 to 1.0% by weight and a second silica-supported chromium catalyst having a pore volume of at least 2 mL/g, a surface area of at least 450 m2/g and a chromium content of 0.1 to 1.0% by weight, wherein the silica support of said first catalyst also comprises alumina and the silica support of said second catalyst also comprises titanium, and preferably a co-catalyst.

Abstract: A novel magnesium treated silica-containing compound that is useful as a support for chromium based olefin polymerization catalyst systems is provided which produces ethylene polymers having with MWD's that promote good properties particularly in HMW film applications.

Abstract: A copolymer of ethylene and a higher alpha-olefin having broadened melt processing windows and reduced melt fracture can be produced using a chromium-containing catalyst system and a trialkyl boron cocatalyst. The polymerization process must be carefully controlled to produce a copolymer resin that easily can be made into articles of manufacture.

Abstract: A process for preparing pillared chromium phyllosilicate clay &agr;-olefin catalysts is disclosed. This process utilizes palygorskite and sepiolite clays. The pillaring of said clays comprises the steps of: (a) preparing a hydrolyzed first solution by dissolving a chromium salt and a base in water, heating said first solution to a temperature in the range of about 20° C. to about 100° C. while stirring continuously until the solution reaches a pH in the range of about 1.5 to about 2.5 and thereby producing a master batch; (b) diluting said master batch with water to produce a diluted second solution and heating said diluted second solution to produce a heated second solution; (c) adding a solid clay selected from the group consisting of sepiolites and palagorskites to said heated second solution, and continuing heating; (d) recovering said pillared chain silicate clay; and (e) drying said pillared chain silicate clay to form first product.

Abstract: A process to produce ethylene polymers is provided.

Abstract: The present invention relates to a process for preparing high density polyethylene in the gas phase comprising contacting ethylene or a mixture comprising ethylene and one or more alpha-olefins with a chromium oxide catalyst supported on a granular or microspherical refractory oxide in a fluidised bed reactor in the presence of oxigen. The present invention further relates to a process for controlling the density of high density polyethylene prepared in the gas phase comprising contacting ethylene or a mixture comprising ethylene and one or more alpha-olefins with a chromium oxide catalyst supported on a granular or microspherical refractory oxide in a fluidised bed reactor in the presence of oxigen.

Abstract: The invention relates to a method for producing supported chromium catalysts for the polymerisation of olefins by loading a xerogel support with chromium by adding to the xerogel support a volume of a 0.025 to 15% by weight solution of a chromium compound or a volume of a solution comprising from 0.025 to 7.8% by weight of Cr which is essentially converted into a chromium(VI) compound on heating in a water-free stream of gas under oxidizing conditions at temperatures in the range from 300 to 1100° C. for a period of from 10 to 1000 minutes in a solvent which comprises a maximum of 20% by weight of water, and subsequently evaporating the solvent, where the volume of the chromium salt solution employed is smaller than the pore volume of the xerogel support.

Abstract: This invention relates to a method for purifying and drying a polymer hydrogel. This invention is based in part upon the discovery that rapid drying of polymer hydrogels can eliminate the problem of unacceptable levels of soluble oligomers caused by prolonged thermal treatment. Rapid drying techniques allow drying hydrogels containing more water than was previously considered possible without a loss in product quality. Furthermore, it was discovered that slurries comprising polymer hydrogels and large quantities of water can be spray dried and that spray drying can be conducted with only minimal oligomer formation.

Abstract: A process to produce ethylene polymers is provided. Particularly, a process to produce ethylene polymers having a broad molecular weight distribution is provided. More particularly, a process to produce ethylene polymers that have low formation of smoke and odor during blow molding is provided.

Abstract: High melt index polyolefins have been obtained with chromium silica catalysts under conventional polymerization conditions without the use of titanium or other additives. The useful chromium silica catalysts have a pore volume in the range of 1.9-2.9 cc/g and a narrow pore size distribution. The silica is a silica gel preferably obtained from a low solids, rapid gelation process.

Abstract: A polyethylene produced by the homopolymerisation of ethylene or copolymerisation of ethylene with &agr;-olefins in the presence of a catalyst, characterized in that the fraction of low molecular weight polymers having MW<5000 g/mole is lower than 12% by weight of the produced polymer, and that the produced polyethylene has a measured melt strength expressed by a haul-off (HO) value satisfying the expression: HO>K1·&eegr;0.05+K2, wherein K1 is 9.10−5 and K2 is 0.4.

Abstract: A novel magnesium treated silica-containing compound that is useful as a support for chromium based olefin polymerization catalyst systems is provided which produces ethylene polymers having with MWD's that promote good properties particularly in HMW film applications.

Abstract: A process is disclosed for producing polyethylene resin of broad molecular weight distribution, when formed into a film, high barrier to moisture (low MVTR (Moisture Vapor Transmission Rate) for the film). The resin is formed by polymerizing ethylene, preferably in a gas phase process or in a slurry process, using a post-titanated catalyst, that is, a catalyst wherein after initial formation of a catalyst comprising Cr—Ti-inorganic refractory support, further titanium is added to the catalyst in a post-titanation step, preferably to increase the titanium content of the catalyst to a final level preferably between 7 and 9.5 wt. %.

Abstract: Disclosed herein are ethylene polymers having a density of 0.95 to 0.955, a melt index from 0.2 to 0.6 g/10 min., a high load melt index from 20 to 70 g/10 min., and a heterogeneity index from 10 to 16, and methods of preparing the same. In certain embodiments the polymers can have a shear ratio from 65 to 100.

Abstract: A process for preventing polymeragglomeration and for controlling the density of copolymer produced by an alpha-olefin copolymerization process in a polymerization reactor, wherein the ratio of the flow rates of introduction of the comonomer(s) to the monomer is kept constant.

Abstract: A process is provided to produce a catalyst system. The process comprises blending a first component and a second component. The first component of the catalyst system comprises chromium on a support. The amount of chromium on the support is from about 0.05 to about 5 weight percent based on the weight of the support. The support comprises fluorided alumina. The support has a surface area from about 200 to about 550 square meters per gram and a pore volume from about 0.7 to about 2.5 cubic centimeters per gram. The first component is activated at a temperature in the range of about 500° C. to about 900° C. The second component is a transition metal halide catalyst. A process comprising polymerizing ethylene or copolymerizing ethylene and at least one other monomer using the catalyst system to produce ethylene polymers is also provided.

Abstract: The present invention relates to a supported chromium-based catalyst titanated under specific conditions and used for the homopolymerisation or the copolymerisation of ethylene. The polyethylene obtained with this catalyst has high shear resirance and environmental stress crack resistance, and can be used for manufacturing films with improved tear properties.

Abstract: An olefin polymerization process is provided comprising contacting an olefin monomer with chromium oxide on a titanium containing silica support having less than about 3 weight percent titanium in combination with an organoboron promoter. Polymers thus produced are useful for blow molding applications.

Abstract: A process for producing high density polyethylene having a bimodal molecular weight distribution, the process comprising pre-contacting a chromium-based catalyst with an alkyl metal oxane, the chromium-based catalyst comprising chromium oxide on a silica-containing support, to form a catalyst system wherein the atomic ratio of the metal of the oxane to the chromium is less than 1, and polymerizing ethylene or copolymerizing ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms in the presence of the catalyst system. A catalyst system for polymerizing ethylene or copolymerizing ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms to produce high density polyethylene, the catalyst system comprising in combination a chromium-based catalyst comprising chromium oxide on a silica-containing support and an alkyl metal oxane with which the chromium-based catalyst has been precontacted whereby the atomic ratio of the metal of the oxane to the chromium is less than 1.

Abstract: A process for the gas-phase (co-)polymerisation of olefins in a fluidised bed reactor using a chromium oxide catalyst. The polymerisation is performed in the presence of a process aid additive.

Abstract: A process for preparing halogen-free, reactive polyisobutene having a terminal double bond content of more than 50 mol % and an average molecular weight Mn of 280-10000 dalton by the cationic polymerization in the liquid phase of isobutene or hydrocarbon mixtures comprising isobutene comprises polymerizing at from −30° C. to +40° C. in the presence of a heterogeneous polymerisation catalyst comprising one or more oxides of the elements of transition groups V and VI of the Periodic Table of the Elements or in the presence of a heterogeneous polymerization catalyst comprising one or more oxidic compounds of one or more elements of transition groups V and VI of the Periodic Table of the Elements supported on a non-zeolitic oxidic support material which is not an oxygen-containing zirconium compound, the catalyst not containing a technically effective amount of halogen.

Abstract: A process for producing a polyethylene resin having a monomodal molecular weight distribution in a single polymerisation reactor using a chromium-based catalyst system, by copolymerising ethylene and an alpha-olefinic-comonomer having from 3 to 8 carbon atoms, the polyethylene resin comprising a blend of a higher molecular weight fraction polymerised by a first chromium-based catalyst of the system and a lower molecular weight fraction polymerised by a second chromium-based catalyst of the system, wherein the comonomer incorporation in the higher molecular weight fraction is greater than the comonomer incorporation in the lower molecular weight fraction is greater than the comonomer incorporation in the lower molecular weight fraction whereby the higher and lower molecular weight fractions differ in density by from 0.01 to 0.03 g/cc.

Abstract: An olefin polymerization apparatus is disclosed wherein monomer, diluent and catalyst are circulated in a continuous pipe loop reactor and an intermediate product slurry is recovered by a continuous product take off means. The intermediate product slurry is passed to a hydrocyclone to stratify polymer particles based on size. A slurry containing predominantly fines is withdrawn overhead and returned to the reaction zone. The slurry containing predominantly fines is preferably returned to the polymerization zone just upstream of the circulation pump and in a preferred embodiment this pressure differential is the sole driving force for the hydrocyclone separation. In another embodiment the product slurry from the bottom of the hydrocyclone is passed to a solids-liquid separator where the solids settle to the bottom and essentially polymer free diluent is recycled. In another embodiment, the intermediate product slurry is withdrawn via a conical settling leg.

Abstract: A process for producing high density polyethylene having a bimodal molecular weight distribution, the process comprising pre-contacting a chromium-based catalyst with an alkyl metal oxane, the chromium-based catalyst comprising chromium oxide on a silica-containing support, to form a catalyst system wherein the atomic ratio of the metal of the oxane to the chromium is less than 1, and polymerising ethylene or copolymerising ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms in the presence of the catalyst system. A catalyst system for polymerising ethylene or copolymerising ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms to produce high density polyethylene, the catalyst system comprising in combination a chromium-based catalyst comprising chromium oxide on a silica-containing support and an alkyl metal oxane with which the chromium-based catalyst has been precontacted whereby the atomic ratio of the metal of the oxane to the chromium is less than 1.

Abstract: A process for producing high density polyethylene suitable for blow molding and having high environmental stress cracking resistance and rigidity copolymerizing ethylene and an alpha-olefinic comonomer comprising from 3 to 10 carbon atoms, in the presence of a chromium-based catalyst, having an alumina-containing support, and an organoboron compound, wherein the atomic ratio of boron in the organoboron compound to the chromium in the chromium-based catalyst is from around 0.2 to around 0.4.

Abstract: An improved chromium oxide-based catalyst supported on a granular or microspherical refractory oxide for the gas phase polymerization of at least one alpha olefin containing from 2 to 12 carbon atoms, wherein the supported chromium oxide-based catalyst has been subjected to a sole calcination/activation step consisting of a single thermal treatment performed at a temperature ranging from 200° to 450° C. under an oxygen containing atmosphere, and an olefin polymerization process employing such catalyst.

Abstract: The invention relates to a method for producing an ethylene polymer, comprising performing polymerization of ethylene in co-presence of hydrogen using a trialkylaluminum compound-carried chromium catalyst, wherein the chromium catalyst is obtained by calcination-activating a chromium compound that is carried on an inorganic oxide carrier in a non-reducing atmosphere to convert chromium atoms in the chromium compound into hexavalent chromium atoms for at least a portion thereof, and treating with a trialkylaluminum compound in an inert hydrocarbon solvent to carry thereon and removing to dry the solvent so that the chromium atoms are not over-reduced by the trialkylaluminum compound, and to an ethylene polymer suitable for blow molded articles obtained by the production method. The ethylene polymer of the invention have improved environment stress crack resistance (ESCR) and impact resistance in a good balance and are suitable for molded blow articles, in particular large size blow molded articles.

Abstract: This invention is directed to reduced oxidation state Group 4-6 metal compounds, preferably the first row metals in those groups, suitable for activation as polymerization catalysts and characterized by comprising a substituted hydrotris(pyrazolyl)borate ancillary ligand and a plurality of single or multidentate uninegative ligands, excluding cyclopentadienyl ligands. The invention includes a polymerization process characterized by comprising contacting one or more monomers polymerizable by coordination or insertion polymerization under suitable polymerization conditions with these catalyst compositions.

Abstract: The invention relates to a process for the production of ethylene polymers by the polymerization of ethylene or the copolymerization of ethylene with one or more C3 to C8 olefins in contact with a chromium-based catalyst deposited on a support essentially consisting of silica. According to the invention, the chromium catalyst is subjected in succession to a heat treatment in nitrogen and then to a heat treatment in air under defined temperature conditions before bringing it into contact with ethylene and, optionally, one or more olefins under polymerizing conditions. The process of the invention makes it possible to manufacture ethylene polymers having an improved compromise between processability, stiffness and resistance to slow crack growth.

Abstract: A copolymer of ethylene and a higher alpha-olefin having broadened melt processing windows and reduced melt fracture can be produced using a chromium-containing catalyst system and a trialkyl boron cocatalyst. The polymerization process must be carefully controlled to produce a copolymer resin that easily can be made into articles of manufacture.

Abstract: An olefin polymerization process is provided comprising contacting an olefin monomer with chromium oxide on a titanium containing silica support having less than about 3 weight percent titanium in combination with an organoboron promoter. Polymers thus produced are useful for blow molding applications.

Abstract: Copolymer of ethylene and of at least one alpha-olefin obtained by means of a catalytic solid base on chromium oxide deposited on an inorganic support, the said copolymer having a melt flow index HLMI, measured in g/10 min, an amount of alpha-olefin Q, pressed in g of alpha-olefin per kg of copolymer, a standard density SD, measured in kg/m3, at least equal to (952.75+5.40×log HLMI−0.79×Q) and a relatively broad molecular mass distribution, characterized by a ratio of the dynamic viscosities &mgr;0/&mgr;2 at least equal to (23.67−6.67×log HLMI).

Abstract: A process comprising polymerizing ethylene with at least one olefin to produce a polymer, and said polymer are provided.

Abstract: A device and method allow a dry catalyst to be delivered to a liquid-filled polymerization reactor, thus avoiding problems associated with catalyst-liquid contact or with undesired addition of gases to the reactor. A quantity of dry catalyst is transferred from a catalyst reservoir maintained under dry conditions to a catalyst chamber. An inert fluid then enters the chamber to flush the catalyst charge toward the reactor. Optional embodiments include means for precontacting the dry catalyst with a modifier and for removing gas from the fluid line.

Abstract: A novel process for producing homopolymers and interpolymers of olefins which involves contacting an olefin and/or an olefin and at least one or more other olefin(s) under polymerization conditions with an olefin polymerization catalyst and at least one ether comprising at least one carbon-oxygen-carbon linkage (C—O—C) of the formula R1—O(—R2—O)m—R3 in amounts sufficient to reduce the electrostatic charge in the polymerization medium. Also disclosed is a process for reducing electrostatic charge in an olefin polymerization medium.

Abstract: A device and method allow a dry catalyst to be delivered to a liquid-filled polymerization reactor, thus avoiding problems associated with catalyst-liquid contact or with undesired addition of gases to the reactor. A quantity of dry catalyst is transferred from a catalyst reservoir maintained under dry conditions to a catalyst chamber. An inert fluid then enters the chamber to flush the catalyst charge toward the reactor. Optional embodiments include means for precontacting the dry catalyst with a modifier and for removing gas from the fluid line.

Abstract: Ethylene polymer having a blow-up ratio (RB) of at least 1.4, a resistance to crazing under stress (ESCR) of at least 55 h and a melt index (MI5) of at least 0.2 g/10 min. Processes for obtaining this ethylene polymer using different catalytic systems, the first based on titanium and zirconium used in a polymerization in two reactors; the second consisting of a mixture of a titanium catalyst and a titanium and zirconium catalyst, used in a polymerization in two reactors; the third based on chromium on a support comprising at least two constituents chosen from silica, alumina and aluminium phosphates, used in a polymerization in a single or in two reactors.

Abstract: A process for producing a polyethylene resin having improved mechanical properties, the process comprising polymerising ethylene in the presence of a chromium-based catalyst to make polyethylene homopolymer in a first polymerisation reactor and in a second polymerisation reactor downstream of the first polymerisation reactor copolymerising ethylene in the presence of the chromium-based catalyst and a co-catalyst from ethylene monomer and comonomer generated in-situ in the second polymerisation reactor to make polyethylene copolymer.