Abstract: In a process for preparing a metal-containing supported catalyst or a metal-containing supported catalyst component by impregnation of a support material with an impregnation solution comprising the metal component, the impregnation solution flows through the support material.

Abstract: The present invention relates to catalyst system containing at least one imidochrome compound and at least one activation compound. This invention also relates to imidochrome compounds, to a method for olefin polymerization and to methods for producing said imidochrome compounds.

Abstract: The co-polymerization reaction of one or more olefin monomers, such as propylene, with &agr;,&ohgr;-diene units and the resulting copolymers are provided. More specifically, the copolymer may have from 90 to 99.999 weight percent of olefins and from 0.001 to 2.000 weight percent of &agr;,&ohgr;-dienes. The copolymer may have a weight average molecular weight in the range from 50,000 to 2,000,000, a crystallization temperature in the range from 115° C. to 135° C. and a melt flow rate in the range from 0.1 dg/min to 100 dg/min. These copolymers may be employed in a wide variety of applications, the articles of which include, for example, films, fibers, such as spunbonded and meltblown fibers, fabrics, such as nonwoven fabrics, and molded articles. The copolymer may further include at least two crystalline populations.

Abstract: The present invention relates to a supported catalyst system for olefin polymerization which comprises at least one metallocene component and a support of an inorganic oxide of silica, aluminum or a polymer containing hydroxyl groups. The support is modified with an organogermane and/or organotin compound. The inventive catalyst system produces minimal reactor fouling, has excellent productivity and good hydrogen responsiveness. The present invention also relates to a process for preparing the catalyst system and to the slurry/suspension or gas-phase polymerization of olefins using the catalytic system, optionally with a small amount of aluminoxane cocatalyst.

Abstract: The polymerization of olefins is carried out in the presence of catalysts comprising at least one complex of a transition metal with a tridentate macrocyclic ligand which additionally bears at least one functional substituent and, if desired, one or more activator compounds. A catalyst system comprising at least one transition metal complex as set forth above and at least one activator compound is also provided.

Abstract: The present invention relates to a process for polymerizing olefin(s) in the presence of metallocene-type catalyst compound, an activator and an inorganic oxide support, a Group 13 containing compound and a carboxylic acid, where the carboxylic acid is added to the polymerization reactor separately. The invention also relates to a process for transitioning from one polymerization catalyst to another.

Abstract: Melt-processible, thermoplastic polyethylene compositions of high resistance against wear are disclosed and methods for making and processing same. Additionally, products comprising these compositions are described.

Abstract: The invention refers to a linear, isotactic polymer which has a structure of one or several C2 to C20 olefins, of which the isotacticity, due to a statistic distribution of stereoscopic errors in the polymer chain, is within the range of from 25 to 60% of [mmmm] pentad concentration with the proviso that an arbitrary or rather regular sequence of isotactic and atactic blocks is excluded, the polymer having a mean molecular weight Mw within the range of from 100,000 to 800,000 gms/mol and a TG of from −50 to +30.

Abstract: A solid catalyst for olefin polymerization, which comprises a silica carrier (A) having a specific surface area of from 600 to 850 m2/g, a pore volume of from 0.1 to 0.8 ml/g and an average particle size of from 2 to 12 &mgr;m, and an organoaluminum-oxy compound (B) and a Group IVB transition metal compound (C) containing a ligand having a cyclopentadienyl skeleton, supported on the carrier (A).

Abstract: Ethylene based polymers having high molecular weights can be obtained in high yields at temperatures of industrial interest, by carrying out the polymerization reaction in the presence of catalysts comprising silicon bridged metallocenes having a particular ligand system containing a heteroatom.

Abstract: The present invention relates to catalyst system containing at least one imidochrome compound and at least one activation compound. This invention also relates to imidochrome compounds, to a method for olefin polymerization and to methods for producing said imidochrome compounds.

Abstract: New polymerization catalyst activators are disclosed which include a heterocyclic compound, which may or may not be substituted, and an aluminum alkyl or an aluminoxane. Supported activators of the invention include the heterocyclic compound, combined with an alkylaluminum or aluminoxane, and a support material, preferably a silica support material. Also disclosed are methods for preparing these catalyst activators and polymerization processes utilizing same.

Abstract: Activator solid support for metallocenes as catalysts in the polymerization of olefins, characterized in that it consists of a group of support particles for a solid catalytic component, which are formed from at least one porous mineral oxide, the said particles having been modified in order to carry, on the surface, aluminum and/or magnesium Lewis-acid sites of formula: groups coming from a functionalization agent having reacted with —OH radicals carried by the base particles of the support, the functionalization reaction having been followed by a fluorination reaction. The catalytic system according to the invention comprises (a) a metallocene catalyst, which has, if required, been subjected to a prealkylation treatment; (b) a cocatalyst; and (c) an activator solid support for metallocene, as defined above, it being possible for the cocatalyst (b) to be absent if the metallocene catalyst (a) has been prealkylated.

Abstract: A polyolefin product is provided which comprises a branched olefin copolymer having an syndiotactic polypropylene backbone, polyethylene branches and, optionally, one or more comonomers. The total comonomer content of the branched olefin copolymer is from 0 to 20 mole percent. Also, the mass ratio of the syndiotactic polypropylene to the polyethylene ranges from 99.9:0.1 to 50:50.

Abstract: A new class of methylene-bridged metallocenes of formula (I), wherein M is a transition metal of group 3, 4, 5, 6, lanthanide or actinide; X is a monoanionic sigma ligand; R1 can be alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl radicals; R2 can be halogen, alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl radical; p is 0-3; m is 0-2; and n is 0-4. Furthermore, the corresponding ligands, a new process for their preparation and catalysts systems containing said methylene-bridged metallocenes are described.

Abstract: The new metallocene catalysts according to the present invention are prepared by reacting a metallocene compound with a compound having at least two functional groups. The metallocene compound is a transition metal compound which a transition metal is coordinated with a main ligand such as cycloalkanedienyl group and an ancillary ligand. The functional groups of the compound having at least two functional groups are selected from the group consisting of a hydroxy group, a thiol group, a primary amine group, a secondary amine group, etc. The metallocene catalysts according to the present invention have a structure which an ancillary ligand of a metallocene compound is bonded with functional groups. A structure of the metallocene catalysts can be varied according to the metallocene compounds, the compound having at least two functional groups, and the molar ratio of each reactant. The metallocene catalyst is employed with a co-catalyst for styrene and olefin polymerization.

Abstract: A polyolefin product is provided which comprises a branched olefin copolymer having an isotactic polypropylene backbone, polyethylene branches and, optionally, one or more comonomers. The total comonomer content of the branched olefin copolymer is from 0 to 20 mole percent. Also, the mass ratio of the isotactic polypropylene to the polyethylene ranges from 99.9:0.1 to 50:50. Additionally, a process is provided for preparing a branched olefin copolymer which comprises: a) copolymerizing ethylene, optionally with one or more copolymerizable monomers, in a polymerization reaction under conditions sufficient to form copolymer having greater than 40% chain end-group unsaturation; b) copolymerizing the product of a) with propylene and, optionally, one or more copolymerizable monomers, in a polymerization reactor under suitable polypropylene polymerization conditions using a chiral, stereorigid transition metal catalyst capable of producing isotactic polypropylene; and c) recovering a branched olefin copolymer.

Abstract: Described are solid olefin polymerization catalysts that have, inter alia, very high productivities (at least 18,000 grams of polyethylene per gram of catalyst in one hour) as shown by a standard test procedure for measuring this property or characteristic. Such particulate catalysts can be prepared by prepolymerizing vinylolefin with a Group 4 metallocene-aluminoxane solution, using proportions of vinylolefin (most preferably, ethylene) in the range of about 150 to about 1500, and preferably in the range of about 175 to about 1000, moles per mole of Group 4 metallocene used in forming the solution. The atom ratio of aluminum to Group 4 metal in the solution is in the range of about 150:1 to about 1500:1, and preferably in the range of about 175:1 to about 1000:1. In addition, the Group 4 metallocene ingredient used in forming these highly productive catalysts has in its molecular structure at least one polymerizable olefinic substituent.

Abstract: A catalyst composition useful for catalyzing the polymerization of olefinic monomers is disclosed, along with a polymerization method using those catalyst compositions to prepare a variety of polyolefins from olefinic monomers. A method for preparation of the catalyst composition by combining an epoxy functional porous organic polymer, a catalytic component, and an activator component is also disclosed.

Abstract: A supported catalyst for olefin polymerization comprises a combination of a sulfated metal oxide support, an aluminoxane and an organometallic complex of a group 4 metal. The sulfated metal oxide may be quickly and conveniently prepared by, for example, contacting the precursor metal oxide with a sulfuric acid. The supported catalyst of this invention is highly active for olefin polymerization in comparison to conventional catalysts which are prepared with non-sulfated supports.

Abstract: A supported catalyst for olefin polymerization comprises a combination of a novel metal oxide support and an activator which is an aluminoxane or a boron activator. The novel metal oxide support of this invention is a conventional particulate metal oxide support material (such as silica or alumina) which has been treated with a halosulfonic acid. A catalyst system which contains this novel catalyst support and a transition metal catalyst is highly active for olefin polymerization (in comparison to prior art catalyst systems which use a conventional metal oxide support).

Abstract: Described are solid olefin polymerization catalysts that have, inter alia, very high productivities as shown by a standard test procedure for measuring this property or characteristic, and excellent morphology. Such particulate catalysts can be prepared by prepolymerizing a controlled amount of vinylolefin with a Group 4 metallocene-alurinnoxane solution, in which the original metallocene ingredient used in the process has in its molecular structure at least one polymerizable olefinic substituent. These particulate catalysts do not contain, and thus are not produced in the presence of, a preformed support such as an inorganic compound (silica or etc.) or a preformed particulate polymeric support.

Abstract: A process for synthesizing syndiotactic 1,2-polybutadiene, the process comprising the steps of (1) polymerizing monomer consisting essentially of 1,3-butadeine monomer within an organic solvent that includes at least 50% by weight of aliphatic solvent by using an iron-based catalyst composition, where said step of polymerizing occurs at a temperature above about 65° C., thereby forming a supersaturated solution of syndiotactic 1,2-polybutadiene, (2) maintaining the supersaturated solution of syndiotactic 1,2-polybutadiene at a temperature above about 65° C. until isolation of the syndiotactic 1,2-polybutadiene is desired, and (3) isolating the syndiotactic 1,2-polybutadiene from the supersaturated solution.

Abstract: A composition useful as an addition polymerization catalyst comprising: A) an inert support; B) a Group 3-10 or Lanthanide metal complex; and C) an activator compound capable of causing the metal complex B) to form an active polymerization catalyst, said compound corresponding to the formula: (A*+a)b(Z*J*j)−cd,  (I)  wherein: A* is a cation of charge +a, Z* is an anion group of from 1 to 50, preferably 1 to 30 atoms, not counting hydrogen atoms, further containing two or more Lewis base sites; J* independently each occurrence is a Lewis acid coordinated to at least one Lewis base-site of Z*, and optionally two or more such J* groups may be joined together in a moiety having multiple Lewis acidic functionality, j is a number from 2 to 12 and a, b, c, and d are integers from 1 to 3, with the proviso that a×b is equal to c×d.

Abstract: A process for the preparation of a poly(&agr;-olefin) copolymer is disclosed wherein the process comprises polymerizing at least one &agr;-olefin, and at least one bulky olefin, in the presence of hydrogen and a catalytically effective amount of catalyst comprising the product obtained by combining a metallocene procatalyst with a cocatalyst, ligand (Cp2R2p) and bridging group R3 contains at least two bulky groups.

Abstract: A phosphinimine catalyst for olefin polymerization is supported on a directly fluorided metal oxide with an aluminoxane. This catalyst is highly active for olefin polymerization in comparison to prior art catalysts which use non-fluorided metal oxide supports. The directly fluorided metal oxide may be conveniently prepared by contacting the precursor metal oxide with a simple alkali metal salt (such as NaF) in an aqueous slurry.

Abstract: The new metallocene catalysts according to the present invention are prepared by reacting a metallocene compound with a compound having at least two functional groups. The metallocene compound is a transition metal compound which a transition metal is coordinated with a main ligand such as cycloalkanedienyl group and an ancillary ligand. The functional groups of the compound having at least two functional groups are selected from the group consisting of a hydroxy group, a thiol group, a primary amine group, a secondary amine group, etc. The metallocene catalysts according to the present invention have a structure which an ancillary ligand of a metallocene compound is bonded with functional groups. A structure of the metallocene catalysts can be varied according to the metallocene compounds, the compound having at least two functional groups, and the molar ratio of each reactant. The metallocene catalyst is employed with a co-catalyst for styrene and olefin polymerization.

Abstract: New polymerization catalyst activators are disclosed which include a heterocyclic compound, which may or may not be substituted, and an aluminum alkyl or an aluminoxane. Supported activators of the invention include the heterocyclic compound, combined with an alkylaluminum or aluminoxane, and a support material, preferably a silica support material. Also disclosed are methods for preparing these catalyst activators and polymerization processes utilizing same.

Abstract: Substituted monocyclopentadienyl, monoindenyl, monofluorenyl and heterocyclopentadienyl complexes of chromium, molybdenum or tungsten in which at least one of the substituents on the cyclopentadienyl ring carries a donor function which is bonded rigidly, not exclusively via sp3-hybridized carbon or silicon atoms, and a process for the polymerization of olefins.

Abstract: A new class of methylene-bridged metallocenes of formula (I), wherein M is a transition metal of group 3, 4, 5, 6, lanthanide or actinide; X is a monoanionic sigma ligand; R1 can be alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl radicals; R2 can be halogen, alkyl, cycloalkyl, aryl, alkylaryl or arylalkyl radical; p is 0-3; m is 0-2; and n is 0-4. Furthermore, the corresponding ligands, a new process for their preparation and catalysts systems containing said methylene-bridged metallocenes are described.

Abstract: A propylene polymerization process is disclosed. The process uses a fluorenyl-indenoindolyl catalyst precursor in the presence of an activator to obtain high molecular weight polypropylene with low degrees of isotacticity and syndiotacticity. In particular, the polypropylene has tacticity such that mmmm is 0-20% and rrrr is 0-60%.

Abstract: The present invention relates to a composition of a carboxylate metal salt in combination with a heated polymerization catalyst to improve the flowability and operability of the catalyst. The invention also relates to methods for preparing the catalyst composition and to its use in a polymerization process.

Abstract: The process features concurrent feeds into the liquid phase of a prepolymerization reaction mixture. These feeds are: a) separate continuous or substantially continuous feeds of (i) a polymerizable vinylolefin, and (ii) a solution in an organic liquid solvent of a metallocene and an aluminoxane and/or metallocene-aluminoxane reaction product; or b) separate continuous or substantially continuous feeds of (i) a polymerizable vinylolefin, (iii) a metallocene optionally in an organic liquid solvent or diluent, and (iv) an aluminoxane optionally in an organic liquid solvent or diluent; or c) separate continuous or substantially continuous feeds of (i) and (ii) and at least one of (iii) and (iv). Particles of catalytically-active, prepolymerized, self-supported olefin polymerization catalyst composition are formed in the reaction medium. The metallocene used as the feed or in making up the feed has at least one polymerizable olefinic substituent in the molecule.

Abstract: A process to produce a first catalyst composition is provided. The process comprises contacting at least one first organometal compound and at least one activator to produce the first catalyst composition. The activator is selected from the group consisting of aluminoxanes, fluoro-organo borates, and treated solid oxide components in combination with at least one organoaluminum compound. In another embodiment of this invention, a process to produce a second catalyst composition for producing bimodal polymers is provided. The process comprises contacting at least one first organometal compound, at least one activator, and at least one second organometal compound to produce the second catalyst composition. The first and second catalyst compositions are also provided as well as polymerization processes using these compositions to produce polymers.

Abstract: A catalyst system useful to polymerize and co-polymerize polar and non-polar olefin monomers is formed by in situ reduction with a reducing agent of a catalyst precursor comprising {CP* MRR′n}+{A}− wherein Cp* is a cyclopentadienyl or substituted cyclopentadienyl moiety; M is an early transition metal; R is a C1-C20 hydrocarbyl; R′ are independently selected from hydride, C1-C20 hydrocarbyl, SiR″3, NR″2, OR″, SR″, GeR″3, SnR″3, and C═C containing groups (R″═C1-C10 hydrocarbyl); n is an integer selected to balance the oxidation state of M; and A is a suitable non-coordinating anionic cocatalyst or precursor. This catalyst system may form stereoregular olefin polymers including syndiotactic polymers of styrene and methylmethacrylate and isotactic copolymers of polar and nonpolar olefin monomers such as methylmethacrylate and styrene.

Abstract: The invention is directed to olefin copolymers composed of nonhydrolyzable monomer units and hydrolyzable monomer units, the latter resulting from copolymerization of monomers containing a linkage that is hydrolytically cleavable in the presence of aqueous base or aqueous acid. Generally, the hydrolyzable monomer units represent a significant fraction of the copolymer, such that upon hydrolysis, a substantial portion of the copolymer is degraded into low molecular weight fragments. Also provided are degradable articles that are at least partially composed of a degradable copolymer in which hydrolyzable monomer units represent at least 20 mole % of the copolymer.

Abstract: The present invention relates to a composition of carboxylate metal salt and a flow improver useful in combination with a polymerization catalyst to improve the flowability and bulk density of the catalyst. The invention also relates to a polymerization process using the catalyst.

Abstract: A polyolefin product is provided which comprises a branched olefin copolymer having an isotactic polypropylene backbone, polyethylene branches and, optionally, one or more comonomers. The total comonomer content of the branched olefin copolymer is from 0 to 20 mole percent. Also, the mass ratio of the isotactic polypropylene to the polyethylene ranges from 99.9:0.1 to 50:50. Additionally, a process is provided for preparing a branched olefin copolymer which comprises: a) copolymerizing ethylene, optionally with one or more copolymerizable monomers, in a polymerization reaction under conditions sufficient to form copolymer having greater than 40% chain end-group unsaturation; b) copolymerizing the product of a) with propylene and, optionally, one or more copolymerizable monomers, in a polymerization reactor under suitable polypropylene polymerization conditions using a chiral, stereorigid transition metal catalyst capable of producing isotactic polypropylene; and c) recovering a branched olefin copolymer.

Abstract: The invention relates to an improved olefin catalyst, a method of in situ-activated catalyst preparation and a process for the polymerization of olefinic monomers via, for example, a titanium trichloride/magnesium dichloride/tetrahydrofuran reaction product catalyst precursor. The activated catalyst is prepared in situ in a polymerization reactor using an alumoxane based co-catalyst wherein the cumbersome traditional steps of catalyst activation and isolation, prior to polymerization are eliminated. An unexpected advantage of this invention is a significant increase in catalyst productivity while maintaining a relatively constant value of the bulk density of polymeric materials produced while concomitantly producing a polymeric product having a broad molecular weight distribution compared with typical alumoxane-activated metallocene catalysts.

Abstract: The present invention relates to a polymerization process in the presence of a bulky ligand metallocene-type catalyst compound having an abstractable fluoride or fluorine containing leaving group.

Abstract: Described are solid olefin polymerization catalysts that have, inter alia, very high productivities as shown by a standard test procedure for measuring this property or characteristic, and excellent morphology. Such particulate catalysts can be prepared by prepolymerizing a controlled amount of vinylolefin with a Group 4 metallocene-aluminoxane solution, in which the original metallocene ingredient used in the process has in its molecular structure at least one polymerizable olefinic substituent. These particulate catalysts do not contain, and thus are not produced in the presence of, a preformed support such as an inorganic compound (silica or etc.) or a preformed particulate polymeric support.

Abstract: A catalyst for olefin polymerization of the formula: R″(C4R′mC5C4R′n)XMeQ wherein X is an hetero atom ligand with one or two lone pair electrons selected from the elements of Group VA or VIA which is substituted or non-substituted: (C4Rm′C5C4Rn′) is a 3,6-substituted fluorenyl; R′ is hydrogen or hydrocarbyl radical having 1-20 carbon atoms, a halogen, an alkoxy, an alkoxy alkyl or an alkylamino or alkylsilyo radical, each R′ being the same or different and m and n independently are 1, 2, 3 or 4, with bilateral symmetry maintained; R″ is a structural bridge between S and (C4R′mC5C4R′n) to impart stereorigidity; Q is a hydrocarbyl radical having 1-20 carbon atoms or a halogen; Me is a Group IIIB, IVB, VB, or VIB metal having any of its theoretically possible oxidation states. Olefin monomers polymerised using these catalysts to form syndiotactic/atactic block polymers of high molecular weight and comprising at least 70% of syndiotactic triads.

Abstract: The invention relates to novel adhesive alpha-olefin inter-polymers which are largely amorphous and have a rheological behavior that makes them suitable for adhesive use, both without and with minimized amounts of tackifying resins. Specifically, the invention poly-alpha olefin inter-polymer may be composed of A) from 60 to 94 mol % of units derived from one alpha mono-olefin having from 3 to 6 carbon atoms and B) from 6 to 40 mol % of units derived from one or more other mono-olefins having from 4 to 10 carbon atoms and at least one carbon atom more than A); and C) optionally from 0 to 10 mol % of units derived from another copolymerizable unsaturated hydrocarbon, different from A) and B); the diad distribution of component A in the polymer as determined by 13C NMR as described herein showing a ratio of experimentally determined diad distribution over the calculated Bernoullian diad distribution of less than 1.

Abstract: Isotactic-polypropylene-based copolymers having a homogenous distribution of recurring units of formula (1): where R is a hydrogen, halide radical or a hydrocarbyl radical optionally containing an atom selected from oxygen, nitrogen, sulphur, phosphorus and silicon, and n is an integer ranging from 1 to 3; said copolymer having a 13C-NMR spectrum wherein the resonance signals attributed to the links between different monomeric units fall around 30, 34, 35, 45 and 47 ppm and present intensities at least two times higher than the resonance signals attributed to styrene—styrene sequences around 41 ppm and 44-46 ppm; a process for preparing said copolymers carried out in the presence of homogeneous catalytic systems comprising a metallocene compound and a cocatalyst; functionalized copolymers obtained from said isotactic-polypropylene-based copolymers; and graft copolymers comprising said isotactic-polypropylene-based copolymers as backbones.

Abstract: A process for synthesizing syndiotactic 1,2-polybutaidene, the process comprising the steps of (1) polymerizing monomer consisting essentially of 1,3-butadeine monomer within an organic solvent that includes at least 50% by weight of aliphatic solvent by using an iron-based catalyst composition, where said step of polymerizing occurs at a temperature above about 65° C., thereby forming a supersaturated solution of syndiotactic 1,2-polybutaidene, (2) maintaining the supersaturated solution of syndiotactic 1,2-polybutaidene at a temperature above about 65° C. until isolation of the syndiotactic 1,2-polybutadiene is desired, and (3) isolating the syndiotactic 1,2-polybutaidene from the supersaturated solution.

Abstract: A polymerization catalyst system and a method for preparing the catalyst system is disclosed. The catalyst system includes a bulky ligand metallocene catalyst compound, preferably containing a single cyclopentadienyl or substituted cyclopentadienyl-type ring system, a Group 13 element containing first modifier, and a cycloalkadiene second modifier. The present invention also provides a process for polymerizing olefin(s) utilizing the catalyst systems described herein.

Abstract: A polymerization catalyst system and a method for preparing the catalyst system is disclosed. The catalyst system includes a bulky ligand metallocene catalyst compound, preferably containing a single cyclopentadienyl or substituted cyclopentadienyl-type ring system, a Group 13 element containing first modifier, and a cycloalkadiene second modifier. The present invention also provides a process for polymerizing olefin(s) utilizing the catalyst systems described herein.

Abstract: Pyridyldiimine ligands having one of the following structures: 1

Abstract: A catalyst composition for polymerization of a conjugated diene or copolymerization of a conjugated diene and an aromatic vinyl compound, which comprises the following components: (A) a metallocene-type complex of a rare earth metal compound (samarium complex etc.), and (B) an ionic compound composed of a non-coordinate anion and a cation (triphenylcarbonium tetrakis(pentafluorophenyl) borate etc.) and/or an aluminoxane. The catalyst composition producing a polymer having a high cis-1,4-configuration content in the microstructure and a narrow molecular weight distribution.

Abstract: The present invention provides a process for producing a polymer having a desired melt index. Pursuant to the process of the present invention an inorganic oxide sample is obtained and dried to a desired extent by controlling the drying conditions. The dried inorganic oxide sample is treated with an organoaluminoxide and a metallocene to form a metallocene catalyst system and contacted with an olefin under conditions supporting polymerization to form a polyolefin sample. The drying conditions are selected to produce an inorganic oxide sample capable of generating a metallocene catalyst system which produces polymer having the desired melt index.