EP1828265A1 - Polyoléfines préparées par un système catalytique comprenant un ziegler-natta et un metallocène dans un réacteur unique - Google Patents

Polyoléfines préparées par un système catalytique comprenant un ziegler-natta et un metallocène dans un réacteur unique

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Publication number
EP1828265A1
EP1828265A1 EP05811022A EP05811022A EP1828265A1 EP 1828265 A1 EP1828265 A1 EP 1828265A1 EP 05811022 A EP05811022 A EP 05811022A EP 05811022 A EP05811022 A EP 05811022A EP 1828265 A1 EP1828265 A1 EP 1828265A1
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EP
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Prior art keywords
metallocene
component
catalyst system
ziegler
catalyst
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EP05811022A
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German (de)
English (en)
Inventor
Abbas Razavi
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Total Petrochemicals Research Feluy SA
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Total Petrochemicals Research Feluy SA
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Priority to EP05811022A priority Critical patent/EP1828265A1/fr
Publication of EP1828265A1 publication Critical patent/EP1828265A1/fr
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F10/00—Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F110/00—Homopolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
    • C08F110/02—Ethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F110/00—Homopolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
    • C08F110/04—Monomers containing three or four carbon atoms
    • C08F110/06—Propene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
    • C08F210/04—Monomers containing three or four carbon atoms
    • C08F210/06—Propene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
    • C08F210/16—Copolymers of ethene with alpha-alkenes, e.g. EP rubbers

Definitions

  • the present invention relates to a catalyst system comprising a Ziegler-Natta component and a metallocene-based catalyst component for use in the preparation of polyolefins having a broad or multi-modal molecular weight distribution.
  • the invention further relates to a process for the polymerisation of olefins using the catalyst system.
  • Polyolefins such as polyethylenes which have high molecular weight generally have high melt strength and improved mechanical properties over their lower molecular weight counterparts.
  • high molecular weight polyolefins can be difficult to process and are more costly to extrude.
  • Cascade reactor technologies comprise in majority two stirred tank slurry reactors, two slurry loop reactors or two gas phase reactors in series. Processes also exist wherein a combination of a loop and a fluidised bed gas phase reactor is employed. Reactor design, configuration, and conditions governing different cascade processes are quite different and may vary substantially from process to process. They all have however one distinct feature: they ensure, in one of the in series configured reactors, the production of a high density low molecular mass polymer component and in the other reactor, the production of a high molecular mass low density polymer fraction.
  • Major challenges in all varieties of cascade technologies are:
  • the final bimodal exhibit well defined melt flow and density.
  • Each cascade technology has its own specificity.
  • the stirred tank slurry process employs gaseous monomer, ethylene with hexane as the preferred solvent as disclosed for example in Boehm (J. Appl. Polym. Sci., 22, 279, 1984). Along with catalysts and co-catalyst hydrogen is fed into the first reactor to reduce the molecular mass in the first stage and butene is introduced into the second reactor to lower the density.
  • the stirred tank technologies have simplified reactor design and are easy to operate. The low monomer partial pressure and long residence times require, however, very high catalysts activities and life times.
  • ethylene with a combination of butene/hexane or hexene/isobutane as co-monomer/solvent pair can be used.
  • the reactors residence times are shorter and catalysts with moderate activities are tolerated.
  • the major challenge in this type of processes is to prevent excess H 2 or co-monomer to enter into the next reactor.
  • a slurry loop reactor may be combined with a fluidised bed gas phase reactor as disclosed by Borealis.
  • the first stage, loop reactor insures rapid start up of the production. It uses propane in supercritical phase as diluent with the advantage of introducing a large quantity of hydrogen for the production of low molecular mass fraction without the risk of H 2 bubble formation and reactor pressure instability. Additionally, polymer dissolution and reactor fouling issues are eliminated due to low solubility in propane whose critical temperature remains below polymer's melting point.
  • the second stage, the gas phase reactor provides good density regulation and excellent product flexibility.
  • Ziegler-Natta catalysts are predominantly used in cascade technologies. They fulfil conditions, such as moderate to high activities, good hydrogen response and co- monomer incorporation capability imposed by the cascade process. Their good thermal and chemical stability guarantees that they survive the relatively long overall residence times of the reactors. They produce however short polymer chains in the high molecular weight low-density fraction that remain in the amorphous phase, and do not contribute to tie molecules formation. Additionally, the branch rich, non-crystallisable low molecular weight material generally leads to de-mixing and phase separation and is not favourable to mechanical properties.
  • Single site catalysts in general and metallocenes in particular are ideally suited to be used in cascade technologies for the production of both fractions of bimodal polyethylene.
  • Selected bridged metallocene catalysts with excellent hydrogen response and co-monomer incorporation capabilities allow the easier production of the bimodal polyethylene without excessive use of hydrogen and co-monomer, and therefore with little or no risk of the second reactor contamination.
  • Their application is particularly advantageous since their narrow disperse polymers, permit precise design of the composition of each fraction particularly that of the low density, high molecular mass fraction.
  • the branches are statistically distributed and are very effective in assisting tie molecule formation and preventing chains longitudinal diffusion and lateral slippage.
  • polymer particle formation starts with catalyst particles being gradually fragmented by infused layers of high density and low-density polymer fractions in tandem reactors to finally become polymer particles.
  • the solid-state morphology of the resulting polyethylene is that of a biphasic polymer alloy, in which the high-density, homo-polymer component acts as the matrix for the low- density copolymer part as can be seen in Figure 1.
  • the high molecular mass copolymer chains traverse several crystalline and amorphous layers and interconnect adjacent crystalline lamellae as tie molecules. Tie molecules density is directly related to the chain length, molecular weight distribution (MWD), number and type of the side branches and the semi-crystalline morphology for a given lamellar thickness.
  • MWD molecular weight distribution
  • the crystalline domain defines low strain rate of semi-crystalline polymers such as modulus, yield stress and slow crack growth properties whereas the amorphous region determines the high strain properties such as impact, tear and fracture resistance.
  • the concentration of the tie molecules determines both the low and high strain rate behaviour.
  • a high concentration of tie molecules can prevent or stop for example the brittle failure that is occasionally initiated, even at low stress, by a small crack and formation of a crazing zone.
  • the crazing zone is formed by highly oriented fibrils under the applied stress concentration and is postulated to be due to disentanglement of tie molecules connecting the micro crystallites and fracture of the fibril.
  • the resistance to fracture is thought to improve by incorporation of various types of branches the long branches being more effective. Branches are predominantly concentrated on tie-molecules that resist the chain pull out through the formation of micro-fibrils: they impede slow crack growth by reducing lamellar thickness and by decreasing the susceptibility to craze initiation and development. Branches also serve to pin-down tie molecules, which are a priori less mobile than their linear counterparts.
  • the pinning of branches at the crystal fold surface and represented in Figure 2 is thought to be responsible for the very high fracture toughness of low density polyethylene (LDPE). High fracture toughness is achieved in the longest branched chains that form tie-molecules. It is also equally important to optimise fracture toughness by regularly spacing the branches, as for example in low-density polyethylene produced with metallocene. The inter branch spacing sets the upper boundary to the effective molecular weight for tie-molecules.
  • LDPE low density polyethylene
  • Production of polyolefin with a bimodal MWD in a single reactor has long been a goal of the polyolefin industry because single reactor configurations are significantly cheaper to build, have improved operability, and enable quicker product transitions than multi-reactor configurations.
  • a single reactor can also be used to produce a broader range of products than can a set of cascaded reactors.
  • Producing a resin having a bimodal MWD in a single reactor requires however highly sophisticated catalytic systems with at least two very different active site populations. It was thought that metallocenes, with their vast structural diversity, could provide highly chemo-selective active site structures with distinctly different hydrogen and co- monomer response and thereby provide a facile route to dual site catalysts.
  • Figure 1 represents the molecular weight distribution of a bimodal polyethylene resin and its relation to the dispersion of the low density fraction, represented by the dark areas, in the high density matrix, represented by the light areas.
  • Figure 2 is a schematic representation of semi-crystalline polyethylene.
  • Figure 3 represents the log/log curve of stress as a function of time for a bimodal polyethylene, showing the transition between ductile and brittle behaviours.
  • It is yet another object of the present invention to provide a catalyst system comprising a catalyst component that has a very high comonomer incorporation to prepare the high molecular weight fraction of the polyolefin and a catalyst component that has a good hydrogen response to prepare the low molecular weight fraction of the polyolefin.
  • the present invention discloses an active catalyst system comprising: a Ziegler-Natta catalyst component; one or more metallocene or new single site catalyst components; an activating agent having an ionising action for the metallocene catalyst component, having low or no co-ordinating capability, said activating agent and Ziegler-Natta (ZN) component having no mutual poisoning or deactivation action; an aluminium alkyl component acting as alkylating agent for the metallocene or new single site component and acting as cocatalysts for the ZN componenent.
  • the Ziegler-Natta catalyst preferably consists of a transition metal component (compound A), which is for example the reaction product of an organomagnesium compound with a titanium compound, and of an organoaluminium component (compound B).
  • compound A a transition metal component
  • compound B an organoaluminium component
  • transition metal compounds suitable for the preparation of compound A there are used tetravalent halogenated titanium compounds, preferably titanium compounds of the general formula TiX n (OR) 4-11 in which n is 1 to 4, X stands for chlorine or bromine, and R for identical or different hydrocarbon radicals, especially straight-chain or branched alkyl groups having 1 to 18, preferably 1 to 10, carbon atoms.
  • TiCI 4 Ti(OC 2 Hs) 2 CI 2 , Ti(OC 2 Hs) 3 CI, Ti(OC 3 Hy) 2 CI 2 , Ti(OC 3 H 7 ) 3 CI, Ti(OiC 3 H 7 ) 2 CI 2 , Ti(OiC 3 H 7 ) S CI, Ti(OiC 4 Hg) 2 CI 2 , Ti(OiC 4 Hg) 3 CI
  • halogeno-ortho-titanic acid esters of the above formula in situ by reacting the respective ortho-titanic acid ester with TiCI 4 in a corresponding proportion.
  • This reaction is advantageously carried out at temperatures of from O to 200 0 C, the upper temperature limit being determined by the decomposition temperature of the tetravalent halogenated titanium compound used; it is advantageously carried out at temperatures of from 60 to 12O 0 C.
  • the reaction may be effected in inert diluents, for example aliphatic or cycloaliphatic hydrocarbons as are currently used for the low pressure process such as butane, pentane, hexane, heptane, cyclohexane, methyl-cyclohexane as well as aromatic hydrocarbons, such as benzene or toluene; hydrogenated Diesel oil fractions which have been carefully freed from oxygen, sulphur compounds and moisture are also useful.
  • inert diluents for example aliphatic or cycloaliphatic hydrocarbons as are currently used for the low pressure process such as butane, pentane, hexane, heptane,
  • reaction product of magnesium alcoholate and tetravalent halogenated titanium compound which is insoluble in hydrocarbons is freed from unreacted titanium compound by washing it several times with one of the above inert diluents in which the titanium-(IV)-compound used is readily soluble.
  • magnesium alcoholates preferably those of the general formula Mg(OR)2 are used, in which R stands for identical or different hydrocarbon radicals, preferably straight-chain or branched alkyl groups having 1 to 10 carbon atoms; magnesium alcoholates having alkyl groups from 1 to 4 carbon atoms are preferred.
  • R stands for identical or different hydrocarbon radicals, preferably straight-chain or branched alkyl groups having 1 to 10 carbon atoms; magnesium alcoholates having alkyl groups from 1 to 4 carbon atoms are preferred.
  • Examples thereof are Mg(OCH 3 ) 2 , Mg(OC 2 H 5 ) 2 , Mg(OC 3 H 7 )2, Mg(Oic 3 H 7 ) 2 , Mg(OC 4 Hg) 2 , Mg(OiC 4 Hg) 2 , Mg(OCH 2 -CH 2 -C 6 Hg) 2 .
  • the magnesium alcoholates can be prepared by known methods, for example by reacting magnesium with alcohols, especially monohydric aliphatic alcohols.
  • Magnesium alcoholates of the general formula X-Mg-OR in which X stands for halogen, (SO 4 )y 2 carboxylate, especially acetate of OH, and R has the above composition, may also be used.
  • These compounds are, for example, obtained by reacting alcoholic solutions of the corresponding anhydrous acids with magnesium.
  • the titanium contents of compound A may be within the range of from 0.05 to 10mg.-atom, per gram of compound A. It can be controlled by the reaction time, the reaction temperature and the concentration of the tetravalent halogenated titanium compound used.
  • the concentration of the titanium component fixed on the magnesium compound is advantageously in the range of from 0.005 to 1.5mmol, preferably from 0.03 to O. ⁇ mmol, per litre of dispersing agent or reactor volume. Generally, even higher concentrations are possible.
  • the organo-aluminium compounds used may be reaction products of aluminium- trialkyl or aluminium -dialkyl hydrides with hydrocarbon radicals having 1 to 16 carbon atoms, preferably AI(iBu) 3 or AI(iBu)2H and diolefins containing 4 to 20 carbon atoms, preferably isoprene; for example aluminium isoprenyl.
  • chlorinated organo-aluminium compounds for example dialkyl-aluminium monochlorides of the formula R 2 AICI or alkyl-aluminium sesquichlorides of the formula R 3 AI2CI 3 , in which formulae R stands for identical or different hydrocarbon radicals, preferably alkyl groups having 1 to 16 carbon atoms, preferably 2 to 12 carbon atoms, for example (C 2 H 5 ) 2 AICI, (JC 4 Hg) 2 AICI, or (C 2 Hs) 3 AI 2 CI 3 .
  • R stands for identical or different hydrocarbon radicals, preferably alkyl groups having 1 to 16 carbon atoms, preferably 2 to 12 carbon atoms, for example (C 2 H 5 ) 2 AICI, (JC 4 Hg) 2 AICI, or (C 2 Hs) 3 AI 2 CI 3 .
  • aluminium-trialkyls of the formula AIR 3 or aluminium-dialkyl hydrides of the formula AIR 2 H in which formulae R stands for identical or different hydrocarbons, preferably alkyl groups having 1 to 16, preferably 2 to 6, carbon atoms, for example AI(C 2 H 5 ) 3 , AI(C 2 H 5 ) 2 H, AI(C 3 H 7 ) 3 , AI(C 3 H 7 J 2 H, AI(IC 4 Hg) 3 , Or AI(IC 4 Hg) 2 H.
  • the organoaluminium may be used in a concentration of from 0.5 to IOmmol per litre of reactor volume.
  • the Ziegler-natta catalyst is prepared with a diether and has a good hydrogen response.
  • the metallocene catalyst components according to the present invention have a structure according to the formula: Rs" (CpR n ) (CpR n ) M Q 2
  • each Cp is a substituted or unsubstituted cyclopentadienyl ring
  • each R is the same or different and is hydrogen or a hydrocarbyl radical such as alkyl, alkenyl, aryl, alkylaryl or arylalkyl radical containing from 1 to 20 carbon atoms or two carbon atoms are joined together to form a C4-C6 ring;
  • - M is a metal group 4 of the Periodic Table
  • - X is a metal group 13 of the Periodic Table
  • - Q is a hydrocarbyl radical such as aryl, alkyl, alkenyl, alkylaryl or arylalkyl radical having from 1 to 20 carbon atoms, a hydrocarboxy radical having from 1 to 20 carbon atoms or a halogen and can be the same or different from each other;
  • - s is equal to 0 or 1.
  • any of the positions on the cyclopentadienyl derivative may comprise a substituent in place of a hydrogen atom. This may be either within the five-membered cyclopentadienyl ring or, if the ligand is for example an indenyl, a tetrahydroindenyl or a fluorenyl, this may be on a carbon atom in the ring system outside of the five-membered ring.
  • Each catalyst component comprises two cyclopentadienyl derivatives that may be the same or different.
  • the type of cyclopentadienyl derivative is not especially limited.
  • the Cp's may be independently selected from cyclopentadienyl-type groups, indenyl-type groups and fluorenyl-type groups.
  • cyclopentadienyl-type group is meant to be a single substituted or unsubstituted cyclopentadienyl ring system and not a fused ring system such as indenyl or fluorenyl systems.
  • R comprises an alkylidene group having from 1 to 20 carbon atoms, a germanium group (e.g. a dialkyl germanium group), a silicon group (e.g. a dialkyl silicon group), a siloxane group (e.g. a dialkyl siloxane group), an alkyl phosphine group or an amine group.
  • the substituent on the bridge comprises a hydrocarbyl radical having at least one carbon, such as a substituted or unsubstituted ethylenyl radical, for example -CH 2 -CH 2 - (Et).
  • R" is Et or Me 2 Si.
  • Q is preferably a halogen and most preferably it is Cl.
  • M is preferably a metal group 4 of the Periodic Table, more preferably it is hafnium or titanium and most preferably, it is hafnium.
  • X is preferably nitrogen.
  • the substituent or substituents present on the ligands are not particularly limited. If there is more than one substiutent, they can be the same or different. Typically, they are independently selected from an hydrocarbyl group having from 1 to 20 carbon atoms. Amongst the preferred substituents, one can cite methyl (Me) groups, phenyl (Ph), benzyl (Bz), naphtyl (Naph), indenyl (Ind), benzendyl (Bzlnd), as well as Et, n-propyl (n-Pr), iso-propyl (I-Pr), n-butyl (n-Bu-, tert-butyl (t-Bu), silane derivatives (e.g. M ⁇ 3 Si), alkoxy preferably given by the formula R-O where R is an alkyl having from 1 to 20 carbon atoms, cycloalkyl and halogen. Preferably there are at most two substituents on each Cp ring
  • the position of the substituent or substituents on the ligands is not particularly limited.
  • the ligands may thus have any substitution pattern including unsubstituted or fully substituted.
  • Cp is a cyclopentadienyl-type group
  • the substituents are preferably in the 3- and/or 5- positions or in the 2- and/or 4- positions.
  • Cp is a fluorenyl-type group
  • the substituents are preferably in the 3- and/or 6- positions or in the 2- and/or 7- positions.
  • Cp is an indenyl-type group
  • the substituents are preferably in the 2- and/or 4- positions.
  • the metallocene catalyst component may be described by the formula
  • R Cp, Rn, M and Q have already been defined and wherein X is an hetero atom ligand with one or two lone pair electrons and selected from the group 15 or 16.
  • X is nitrogen, phosphorus oxygen or sulfur and it can be substituted or unsubstituted.
  • the Ziegler-Natta catalyst component is prepared with a diether and is used to prepare the low molecular weight fraction of the polymer because of its good response to hydrogen.
  • the metallocene catalyst component is a hafnocene and it is used to prepare the high molecular weight fraction of the polymer because of its good comonomer incorporation.
  • the other one or more catalyst component(s) can be a new single site catalyst component given by formula III
  • L is an heteroatom-containing ligand
  • M' is selected from Ti, Zr, Sc, V, Cr, Fe, Co, Ni, Pd or a lanthanide metal
  • each Q is independently a hydrocarbon having from 1 to 20 carbon atoms or a halogen
  • p is the valence of M' minus the coordination number of L and such as described for example in Britovsek et al. (Britovsek, G.J. P., Gibson, V.C., Kimberley, B.S., Maddox, P.J., McTavish, S.J., , Solan, G.A., White, A.J. P. and Williams, D.J., in J. Chem.
  • These new catalyst components include iron and cobalt complexes of the 2,6-bis(imino)pyridyl ligand, comprising two 2,6-diisopropylaniline groups linked to a 2,6-substituted pyridine group, thus forming a tridentate ligand.
  • the substituents on the two diisopropylaniline groups can be the same or different and typically, they can be selected from hydrogen, methyl or iso-propyl, preferably they all are methyl.
  • the metal is iron because the complexes based on iron do not incorporate the comonomer, thereby producing a polyolefin of high crystallinity.
  • the comonomer reacts with the iron-based complexes as a chain transfer thereby favouring formation of a very low molecular weight fraction.
  • the catalyst system of the present invention comprises one Ziegler-Natta catalyst component and at least one other metallocene or new single site catalyst component preferably, a nickel-based complex. It comprises, in addition to the above catalyst components, one or more activating agents having an ionising action and capable of activating the metallocene catalyst component(s) without poisoning the Ziegler-Natta catalyst component.
  • the activating agents of the present invention are selected from spherically-shaped anionogenic agents that can distribute the negative charge evenly and that have a low or no co-ordinating capability. Preferably, they are selected from borates, boranes and aluminates or mixtures thereof.
  • Suitable boron-containing compounds activating agents may comprise triphenylcarbenium boronate, such as tetrakis-pentafluorophenyl-borato- triphenylcarbenium as described in EP-A-0,427,696
  • activators are highly effective for olefin polymerisation.
  • Functionalised fluoroarylborate salts are preferred as they have improved solubility in hydrocarbons and improved thermal stability while keeping an excellent efficiency for olefin polymerisation.
  • Other suitable boron-containing activating agents are described in EP-A-0,277,004. They can be represented by the general formula:
  • L' is a neutral Lewis base
  • H is a hydrogen atom
  • [U-H] + is a Bronsted acid
  • B is boron in a valence state 3
  • An and Ar 2 are the same or different and are aromatic or substituted aromatic hydrocarbon radicals containing from 6 to 20 carbon atoms and may be linked to each other through a stable bridging group
  • X 3 and X 4 are radicals selected independently from the group consisting of hydride radicals, halide radicals, with the proviso that only X 3 or X 4 will be halide at the same time, hydrocarbyl radicals containing from 1 to 20 carbon atoms, substituted hydrocarbyl radicals containing from 1 to 20 carbon atoms, wherein one or more of the hydrogen atoms is replaced by a halogen atom, hydrocarbyl- substituted metal radicals wherein each hydrocarbyl substitution contains from 1 to 20 carbon atoms and wherein the metal is selected from group 14 of the Periodic Table of the Elements
  • Suitable aromatic radicals An and Ar 2 may include phenyl, naphtyl or anthracenyl radicals, and suitable substituents on the aromatic radicals may include hydrocarbyl radicals, organometalloid radicals, alkoxy radicals, alkylamido radicals, fluoro- and fluoro-hydrocarbyl radicals and radicals such as those that can be useful as X 3 and X 4 .
  • the substituents may be ortho-, meta- or para-, relative to the carbon atom bonded to the boron atom.
  • each may be the same or a different aromatic or substituted aromatic radical, the same or a different straight or branched alkyl, alkenyl or alkynyl radical having from 1 to 20 carbon atoms, the same or a different cyclic hydrocarbon radical having from 5 to 8 carbon atom, or an alkyl-substituted cyclic hydrocarbon having from 6 to 20 carbon atoms, the same or a different alkoxy or dialkylamido radical wherein the alkyl portion has from 1 to 20 carbon atoms, the same or different hydrocarbyl radicals or organometalloid radicals having from 1 to 20 carbon atoms.
  • An and Ar 2 may be linked to one another.
  • either or both of An and Ar 2 may be linked to either X 3 or X 4 and X 3 and X 4 may be linked to one another through a suitable bridging group.
  • Boron compounds which may be used in the present invention include trialkyl- substituted ammonium salts such as for example triphenylammonium tetra(phenyl)boron, tripropylammonium tetra(phenyl)boron, tri(n-butyl)ammonium tetra(phenyl)boron, trimethylammonium tetra(p-tolyl)boron, trimethylammonium tetra(o-tolyl)boron, tributylammonium tetra(pentafluorophenyl)boron, tripropylammonium tetra(o,p-dimethylphenyl)boron, tributylammonium tetra(m,m- dimethylphenyl)boron, tributylammonium tetra(p-trifluoromethylphenyl)boron, tri(n- butyl)ammonium tetra(o-tolyl)boro
  • N,N-dialkyl anilium salts can be used, such as for example N,N-dimethylanilium tetra(phenyl)boron, N,N-diethylanilium tetra(phenyl)boron, N,N-2,4,6 pentamethylanilium tetra(phenyl)boron.
  • Dialkyl ammonium salts can be used such as for example di-(l-propyl)ammonium tetra(pentafluorophenyl)boron, dicyclohexylammonium tetra(phenyl)boron.
  • Triaryl phosphonium salts can be used such as for example triphenylphosphonium tetra(phenyl)boron, tri(methylphenyl)phosphonium tetra(phenyl)boron, tri(dimethylphenyl)phosphonium tetra(phenyl)boron.
  • activating agents such as (perfluoroaryl) boranes and aluminates are disclosed in Chen and Marks (Chen E.Y-X., Marks T.J., in "Cocatalysts for metal-catalysed olefin polymerisation: activators, activation processes, and structure-activity relationship.”, Chem. Rev. ,100, 1391-1434, 2000.)
  • the role of borane and aluminate activating agents for tuning cation-anion ion pair structure and reactivity is disclosed in Chen et al.
  • aluminium alky Is are used as cocatalyst for the Ziegler- Natta catalyst component. They are represented by the formula AIR x wherein each
  • R is the same or different and is selected from halides or from alkoxy or alkyl groups having from 1 to 12 carbon atoms and x is from 1 to 3.
  • Especially suitable aluminiumalkyl are trialkylaluminium, the most preferred being triisobutylaluminium (TIBAL).
  • the catalyst system may be employed in a solution polymerisation process, which is homogeneous, or a slurry process, which is heterogeneous.
  • typical solvents include hydrocarbons having from 4 to 7 carbon atoms such as heptane, toluene or cyclohexane.
  • hydrocarbons having from 4 to 7 carbon atoms such as heptane, toluene or cyclohexane.
  • a slurry process it is necessary to immobilise the catalyst system on an inert support.
  • the Ziegler-Natta component is supported on a MgCb support.
  • the one or more metallocene component(s) can either be supported on the same support as the Ziegler-Natta component or on a different support. If the metallocene component is deposited on a different support, it is preferred to select a porous solid support such as talc, inorganic oxides and resinous support materials such as polyolefins.
  • the support material is an inorganic oxide in its finely divided form.
  • Suitable inorganic oxide materials that may be employed in accordance with this invention include group MA, IMA, IVA, or IVB metal oxides such as silica, alumina and mixtures thereof.
  • Other inorganic oxides that may be employed either alone or in combination with the silica, or alumina are for example magnesia, titania or zirconia.
  • Other suitable support materials comprise for example finely divided functionalised polyolefins such as finely divided polyethylene.
  • the support is a silica support having a specific surface area of from 200 to 700 m 2 /g and a pore volume of from 0.5 to 3 ml/g.
  • the two or more catalyst components can be immobilised on the same support or on different supports, preferably on different supports.
  • the relative amounts of the Ziegler-Natta catalyst component and of the other one or more metallocene catalyst component(s) depend upon the desired properties of the final resin and upon the activity of each catalytic component.
  • the amount of Ziegler-Natta component can range from 10 to 90 wt% of the total weight of the Ziegler-Natta and other metallocene catalyst components.
  • the amount of Ziegler-Natta component is typically of no more than 50 wt%, based on the weight of all catalyst components.
  • the Ziegler-Natta and the metallocene components are added each according to their activity and according to the desired properties of the final product.
  • the amounts of activating agent and of total metallocene components usefully employed in the preparation of the catalyst system can vary over a wide range.
  • the amount of boron is near stoichiometric with respect to the total amount of metal present in the one or more metallocene catalyst components.
  • the boron (B) to total metal ( ⁇ M) ratio B/ ⁇ M is in the range between 1 :1 and 20:1 , preferably, it is about 2:1.
  • the order of addition of the catalyst components and activating agent to the support material can vary.
  • the boron-based activating agent dissolved in a suitable inert hydrocarbon solvent is added to a support material slurried in the same or another suitable hydrocarbon liquid. Thereafter the catalyst components are added either to the same or to different slurries.
  • Preferred solvents include mineral oils and the various hydrocarbons which are liquid at reaction temperature and which do not react with the individual ingredients.
  • Illustrative examples of the useful solvents include the alkanes such as pentane, iso-pentane, hexane, heptane, octane and nonane; cycloalkanes such as cyclopentane, cyclohexane, and aromatics such as benzene, toluene, ethylbenzene and diethylbenzene.
  • the support material is slurried in toluene and the catalyst components and activating agent are dissolved in toluene prior to addition to the support material.
  • the present invention further discloses a process for preparing a catalyst system that comprises the steps of:
  • each Cp is a substituted or unsubstituted cyclopentadienyl ring
  • each R is the same or different and is hydrogen or a hydrocarbyl radical such as alkyl, alkenyl, aryl, alkylaryl or arylalkyl radical containing from 1 to 20 carbon atoms or two carbon atoms are joined together to form a C4-C6 ring;
  • - M is a metal group 4 of the Periodic Table
  • - Q is a hydrocarbyl radical such as aryl, alkyl, alkenyl, alkylaryl or arylalkyl radical having from 1 to 20 carbon atoms, a hydrocarboxy radical having from 1 to 20 carbon atoms or a halogen and can be the same or different from each other;
  • - s is equal to 0 or 1 ;
  • - X is an heteroatom ligand with one or two lone pair electrons and selected from the group 15 or 16, substituted or unsubstituted; or new single site catalyst component of general formula III
  • L is an heteroatom-containing ligand
  • M' is selected from Ti, Zr, Sc, V, Cr, Fe, Co, Ni, Pd or a lanthanide metal
  • each Q is independently a hydrocarbon having from 1 to 20 carbon atoms or a halogen
  • p is the valence of M' minus the coordination number of L
  • step C providing an activating agent having an ionising action and capable of activating the one or more metallocene catalyst component(s), said activating agent being based on a spherically shaped anionogenic agent that can distribute the negative charge evenly and that has a low or no co ⁇ ordinating capability and said activating agent and said Ziegler-Natta component of step A having no mutual poisoning action;
  • the catalyst systems of the present invention can be used to produce polyolefins with broad or multimodal molecular weight distribution.
  • the metallocene, new single site and Ziegler-Natta components are selected according to the desired polymer properties.
  • the Ziegler-Natta catalyst component is prepared with a diether and has an very good hydrogen response: it is thus capable of producing the low molecular weight, high crystallinity fraction.
  • the additional metallocene catalyst component is preferably selected to have a good comonomer incorporation and the capability to produce the polymer fraction having a high molecular weight and a low crystallinity.
  • a bridged hafnocene or constrained geometry titanocene are the most preferred single site components: - a large opening angle of the structure, produced by a small bridge containing a single carbon or silicon atom, allows an excellent comonomer incorporation; the electronic environment of the metal is favourable to prepare the high molecular weight low crystallinity fraction of the final polymer.
  • Example of small bridges are CMe2, SiMe2 or CPh 2 .
  • the metallocene catalyst component preferably has Cs bilateral symmetry such as for example in the cyclopentadienyl-fluorenyl-type group. If an isotactic polypropylene is prepared, the metallocene catalyst component preferably has C1 or C2 symmetry such as for example in the indenyl-type group or an unsymmetrically substituted cyclopentadienyl-fluorenyl-type group.
  • the Ziegler-Natta catalyst component is prepared with a phthalate and has a poor hydrogen response and a good comonomer response: it is used to prepare the high molecular weight fraction of the final polymer.
  • the metallocene component is then selected to produce the low molecular weight, high crystallinity fraction of the final polymer: it is characterised by a small opening angle in the structure and a good response to hydrogen. Unbridged metallocene structures produce good results.
  • the low molecular weight, high density fraction may be prepared with an iron-based new single site component. A large amount of comonomer is necessary to produce the high molecular weight fraction with the ZN catalayst component and that excess comonomer also acts as chain transfer agent for the iron-based complex.
  • the present invention thus further discloses a process for the preparation of polyolefins having a broad, bi- or multi-modal molecular weight distribution comprising the steps of;
  • the preferred comonomers are selected from octene, 3-methyl-1-pentene or 4- methyl-1-pentene.
  • polymerisation takes place in the presence of hydrogen and of an alkene co-monomer such as 1-butene or l-hexene.
  • the polymerisation process is preferably carried out at a temperature of from 50 to 12O 0 C, more preferably from 60 to 11O 0 C, under an absolute pressure of 1 to 100 bar.
  • pre-polymerisation can be carried out.
  • the polyolefins prepared according to the present invention have a broad, bi- or multi-modal molecular weight distribution with a large, medium or small molecular weight difference between the high and the low molecular weight fractions. Additionally, the high molecular weight fraction of the polyolefin typically has a density of from 0.9 to 0.945 g/cm 3 . The density is measured at 23 0 C following the method of standard test ASTM D 1505. The low molecular weight fraction has a density of at least 0.950 g/cm 3 .
  • the molecular weight distribution is defined by the polydispersity index D that is the ratio Mw/Mn of the weight average molecular weight Mw to the number average molecular weight Mn, as determined by gel permeation chromatography (GPC).
  • the molecular weight distribution typically ranges from 4 to 20.
  • the molecular weight distribution of the first polyolefin component overlaps with the molecular weight distribution of the second polyolefin component, thus forming a polymer product that has at least a bimobal molecular weight distribution.
  • the present invention utilises at least two catalyst components for producing at least two polymer components, each component forming part of the multimodal polymeric product. It is preferred that two catalysts are employed, and a bimodal polymer product is produced. However, the invention is not limited to bimodal products only, and multimodal polymers may be produced if desired.
  • the polymerising steps take place in a single reaction zone, under polymerising conditions in which the catalysts producing the polymer components are simultaneously active.
  • the catalysts employed in the present invention are still particularly effective in producing the required polyolefin components of a multimodal product even when these components are produced in separate reactors. Accordingly, in some embodiments, separate reactors may be employed for forming some or all of the components, if desired.
  • the olefin monomer employed typically comprises ethylene and/or propylene.
  • Bimodal or multimodal polyethylene is the most preferred product.
  • the catalyst systems employed in the present invention may be employed in any type of co-polymerisation method, provided that the required catalytic activity is not impaired.
  • the catalyst system is employed in a slurry process, which is heterogeneous.
  • Preferred supports include a porous solid support such as talc, inorganic oxides and resinous support materials such as polyolefin.
  • the support material is an inorganic oxide in its finely divided form.
  • the support is a silica support having a surface area of from 200-700 m ⁇ /g and a pore volume of from 0.5-3 ml/g.
  • the amount of activating agent and catalyst component usefully employed in the preparation of the supported catalyst system can vary over a wide range and depend upon the nature of the activating agent.
  • the order of addition of the catalyst components and activating agent to the support material can vary.
  • the support material is slurried in toluene and the catalyst components and activating agent are dissolved in toluene prior to addition to the support material.
  • the present invention also provides an olefin polymer, obtainable according to a method as defined above.
  • the most preferred polymer obtainable according to the present invention is high density polyethylene (HDPE).
  • HDPE high density polyethylene
  • Also provided is the use of a dual catalyst system for producing an olefin polymer.
  • Resins having a bimodal molecular weight distribution can be used in high density, blown film, application where they offer an attractive combination of rheological properties in terms of shear response, low die swell, and high melt strength and of physico- mechanical properties such as clarity/low gel, tear strength, Environmental Stress Crack Resistance (ESCR). They further offer a good compromise of stiffness and impact resistance.
  • HDPE high-density polyethylene
  • Blow moulding grades have excellent processing capabilities because of their low die swell and high melt strength. They also have good mechanical properties in terms of stiffness and ESCR.
  • the containers prepared with the resins of the present invention can thus have thin walls, thereby requiring less material, and yet evince the resins having the best combination of top-load and ESCR.
  • Pressure pipe for natural gas and drinking water distribution is another fast growing application for bimodal HDPE.
  • the performance criteria for pressure pipes are processability during the extrusion through annular dies as well as short and long term performance properties requiring resistance to environmental (chemical and mechanical) stress ESCR, Slow Crack Growth (SCG), and Rapid Crack Propagation (RCP). They must compete with incumbent materials such as concrete and steel having long service lives of over 50 years.
  • High performance pipes produced with the bimodal resin according to the present invention have the ability to resist short and long term failure mechanism such as growth of an incidental crack in the pipe over long periods of time under constant pressure (SCG), and resistance to RCP as a results of impact of a sharp object (impact failure). Additionally and most importantly, they exhibit high creep rupture strength (high modulus, high stiffness).
  • SCG constant pressure
  • RCP resistance to RCP as a results of impact of a sharp object (impact failure). Additionally and most importantly, they exhibit high creep rupture strength (high modulus, high stiffness).
  • the service lifetime is estimated via Long- Term Hydrostatic Strength (LTHS) that is determined by Minimum Required Stress (MRS) tests. These tests require a series of pressure/ failure time curves established at different temperatures with a number of pipes having prescribed length, diameter and wall thickness. Calculations and extrapolations are then carried out following the method developed by Schulte (U. Schulte in 100 ceremonies Lebensdauer; Kunststoffe, 87, p.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)

Abstract

L'invention porte sur un système de catalyseur métallocène permettant de produire des polyoléfines, lequel système comprend: A) un composant de catalyseur Ziegler-Natta; B) un ou plusieurs composants métallocènes ou post-métallocènes; C) un agent activant ayant une action ionisante sur le composant de catalyseur métallocène, possédant une capacité de coordination faible ou nulle et n'exerçant pas d'action d'empoisonnement sur le composant Ziegler-Natta.
EP05811022A 2004-10-21 2005-10-20 Polyoléfines préparées par un système catalytique comprenant un ziegler-natta et un metallocène dans un réacteur unique Withdrawn EP1828265A1 (fr)

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EP05811022A EP1828265A1 (fr) 2004-10-21 2005-10-20 Polyoléfines préparées par un système catalytique comprenant un ziegler-natta et un metallocène dans un réacteur unique

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EP04105217A EP1650230A1 (fr) 2004-10-21 2004-10-21 Polyoléfines préparées par un système catalytique comprenant un Ziegler-Natta et un metallocène dans un réacteur unique
EP05811022A EP1828265A1 (fr) 2004-10-21 2005-10-20 Polyoléfines préparées par un système catalytique comprenant un ziegler-natta et un metallocène dans un réacteur unique
PCT/EP2005/055396 WO2006045737A1 (fr) 2004-10-21 2005-10-20 Polyolefines preparees a partir de composants de catalyseur metallocenes et ziegler-natta dans un seul reacteur

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EP05811022A Withdrawn EP1828265A1 (fr) 2004-10-21 2005-10-20 Polyoléfines préparées par un système catalytique comprenant un ziegler-natta et un metallocène dans un réacteur unique

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WO2008077530A2 (fr) * 2006-12-22 2008-07-03 Basell Polyolefine Gmbh Composition de polyéthylène multimodale, catalyseur mixte et procédé de préparation de la composition
DE102007017903A1 (de) 2007-04-13 2008-10-16 Basell Polyolefine Gmbh Polyethylen und Katalysatorzusammensetzung und Verfahren zu dessen Herstellung
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