NZ501653A - Process for the polymerisation of ethylene in the presence of a transitional metal catalyst (Zr, Ti, Hf) - Google Patents

Abstract

A process for polymerizing ethylene or copolymerising and one or more alpha-olefins in the gas phase. The process involves: (a) in a first stage polymerizing ethylene or ethylene and one or more alpha-olefins in the gas phase at a temperature in the range of 20 to 70oC in the presence of a catalyst system comprising (1) a supported constrained geometry complex and (2) an activator; (b) optionally, recovering the prepolymerised catalyst; and (c) in a second stage polymerizing ethylene or ethylene and one or more alpha-olefins in the gas phase at a temperature in the range 65 to 100oC in the presence of the prepolymerised catalyst. The constrained geometry complex preferably has the formula (I) wherein; R' in each occurrence is independently selected from hydrogen, hydrocarbyl, silyl, germyl, halo, cyano, and combinations thereof, the R' having up to 20 non-hydrogen atoms, and optionally, two R' groups (where R' is not hydrogen, halo or cyano) together form a divalent derivative thereof connected to adjacent positions of the cyclopentadienyl ring to form a fused ring structure; X is a neutral h4-bonded diene group having up to 30 non-hydrogen atoms, which forms a p-complex with M; Y is O, S, NR*, PR*; M is titanium or zirconium in the +2 formal oxidation state; Z* is SiR*2, CR*2, SiR*2SiR*2, CR*2CR*2, CR*=CR*, CR2SiR*2, or GeR*2; wherein R* in each occurrence is independently hydrogen or a member selected from hydrocarbyl, silyl, halogenated alkyl, halogenated aryl, and combination thereof, the R* having up to 10 non-hydrogen atoms, and optionally, two R* group from Z* (where R* is not hydrogen), or an R* group from Z* and an R* group from Y form a ring system.

Description

New Zealand Paient Spedficaiion for Paient Number 501 653 WO 99/00431 PCT/GB97/01730 PROCESS FOR THE POLYMERISATION OF OLEFINS IN THE GAS PHASE The present invention relates to a process for the polymerisation of olefins and in particular to a process for the homopolymerisation of ethylene or copolymensation of ethylene and alpha-olefins in the gas phase by use of a prepolymensed transition metal complex catalyst 5 Traditional olefin polymerisation catalysts have been based on transition metal salts of Group IV to VIII metals m combination with base metal alkyls of Group I to III metals Such catalysts known as Ziegler-Natta catalysts have been used to polymerise olefins in solution, slurry and gas phase processes Another catalyst system used for polymerisation of olefins is based on chromium oxide and 10 is often referred to as Phillips-type catalyst system A problem encounteied when such catalyst systems have been used in the gas phase has been the contiol of the morphology of the polymer produced The morphology of polymeis pioduced in the gas phase has been improved by use of prepolymerisation processes in which typically in a first stage the contact between 1 5 one or more olefins with the Ziegler-Natta catalyst results in the formation of a prepolymer in the form of solid particles In a second stage the prepolymer is contacted with one or more olefins under polymerisation conditions in the gas phase to produce polymei s directly in the form of powders In this way the morphology of the final polymer may be improved A typical prepolymerisation 20 process is described in EP 99774 Catalysts based on cyclopentadienyl metal complexes have also been widely used for the polymerisation of olefins These complexes may be used in catalyst systems which comprise a bis(cyclopentadienyl) transition metal complex and a cocatalyst Such bis (Cp) transition metal complexes have been referred to as 25 metallocenes and are typically based on titanium or zirconium metals and may be Printed from Mimosa WO 99/00431 PCT/GB97/01730 2 cocatalysed with aluminium compounds such as alummoxanes When used in gas phase processes such bis (Cp) metallocene systems may be supported on silica More recently another type of transition metal complex has been used to prepare olefin polymers Such complexes have a single cyclopentadienyl ring 5 ligand and a hetero atom bonded to the metal atom and may also be used in conjunction with aluminoxanes Such 'constrained geometry' catalysts are described in EP 420436 and EP 416815 Similar catalyst systems are taught in EP 418044 and WO 92/00333 In these systems the catalyst is prepared as the product of a mono(cyclopentadienyl) 10 heteroatom metal complex and an ionic activator compound and such systems have been referred to as ionic mono(cyclopentadienyl) catalysts Typical ionic activators foi such systems may be exemplified by borates The complexes described above may be optionally prepolymerised For example WO 93/23439 describes supported bis (Cp) metallocene catalyst systems, 1 5 activated with alumoxanes which may be optionally prepolymerised in order to impart improved catalyst particle strength In this reference the prepolymerisation is performed in the slurry phase at a temperature in the range -15°C to 30°C preferably at less than 25°C Further examples of the use of prepolymerisation with such bis (Cp) 20 metallocene complexes may be found in EP 452920, EP 516458, EP 582480 and EP 605952 WO 94/03506 describes supported ionic catalysts based on mono (cyclopentadienyl) complexes and ionic activators which may also be optionally prepolymerised in order to achieve improved particle strength and size and reduced 25 reactor fouling during polymerisation WO 94/28034 describes supported bridged bis (Cp) metallocene catalysts in which prepolymerisation i educes the reactor fouling tendencies of the catalyst and enhances the particle morphology control of the final polymer formed WO 96/00243 describes chiral metallocenes for the production of highly 30 isotactic polypropylene copolymers in which prepolymerisation is found to improve particle morphology In all these systems the valency of the transition metal in the metallocene complex is in either the +3 or more usually in the highest oxidation state of +4 WO 95/00526 describes titanium oi zirconium complexes in which the 35 transition metal is in the +2 formal oxidation state The complex also comprises a Printed from Mimosa WO 99/00431 IV v ■ w w -w PCT/GB97/01730 501653 neutral, conjugated or non-conjugated diene ligand which forms a 7t-complex with the metal Such complexes are rendered catalysts by combination with an activating cocatalyst for example aluminoxanes, boranes or borates When used in a gas phase process these catalysts are suitably supported on silica However there 5 is no mention of prepolymerisation as an option when using such catalyst systems in the gas phase Accordingly in the above complexes when prepolymerisation has been suggested it is in order to either reduce reactor fouling or to improve the morphology of the final polymer both advantages typically claimed with the earlier 10 Ziegler-Natta or chromium systems We have now found that prepolymersation in the presence of transition metal complexes may be used to improve reactivity in particular when performed in the gas phase, for example in an agitated dry phase reactor In particular we have now found that the catalytic activity of certain 1 5 transition metal complex catalysts in the gas phase may be improved by use of an initial prepolymerisation step performed at low temperature (with respect to the final polymerisation temperature) either in a separate stage or in-situ prior to the final polymerisation stage Thus according to the present invention there is provided a process for 20 polymerising ethylene or copolymerising ethylene and one or more alpha-olefins in the gas phase comprising - (1) m a first stage prepolymerising ethylene or ethylene and one or more alpha-olefins in the gas phase at a temperature in the range 20 to 70°C in the presence of a catalyst system comprising (a) a supported constrained geometry complex and (b) an activator, (2) optionally, recovering the prepolymerised catalyst, and (3) in a second stage polymerising ethylene or ethylene and one or more alpha-olefins in the gas phase at a temperature in the range 65 to 100°C in the presence of said 2q prepolymerised catalyst.

The term 'constrained geometry complex' will be readily understood by one skilled in the art to mean complexes in which the metal atom is forced into greater exposure of the active metal site because of one or more substituents on the delocalised TT bonded moiety. Such complexes are described in detail in EP 416815 INTELLECTUAL PROPERTY OFFICE OF N.Z. - 4 SEP 2001 RECEIVED WO 99/00431 nil h CT/GB97/01730 501653- incorporated herein by reference.

The process of the present invention may be performed in a single gas phase reactor in which both stages are performed or the prepolymerised catalyst from the first stage may be recovered before use in the final polymerisation.

The prepolymerised catalyst may be recovered by conventional means.

The prepolymerisation stage is most preferably carried out at a temperature in the range 20 to 65°C most preferably in the range 25-40°C and the final polymerisation stage at a preferred temperature in the range just above 65°C to 100°C, most preferably in the range 70 to 85°C.

During the prepolymerisation stage the pressure is typically in the range 0.1 to 10 bar In the final polymerisation stage the pressure is increased and is typically in the range 5 to 20 bar Titanium (II) or zirconium (II) complexes are particularly suitable for use as the constrained geometry complex in the process of the present invention Such 1 5 complexes are disclosed in the aforementioned WO 95/00526 which is incorporated herein by reference The complexes have the general formula'- wherein R' each occurrence is independently selected from hydrogen, hydrocarbyl, 25 silyl, germyl, halo, cyano, and combinations thereof, said R' having up to 20 non hydrogen atoms, and optionally, two R' groups (where R1 is not hydrogen, halo or cyano) together form a divalent derivative thereof connected to adjacent positions of the cyclopentadienyl ring to form a fused ring structure, X is a neutral bonded diene group having up to 30 non-hydrogen 30 atoms, which forms a 7r-complex with M, Y is -0-, -S-, -NR*-, -PR*-, M is titanium or zirconium in the +2 formal oxidation state; Z* is SiR*2, CR*2, SiR*2SiR*2, CR*2CR*2, CR* = CR*, CR2SiR*2, or GeR*2, wherein R* each occurrence is independently hydrogen, or a member selected from INTELLECTUAL PROPERTY OFFICE OF N.Z. - < SEP 2001 RECEIVED WO 99/00431 PCT/GB97/01730 hydrocarbyl, silyl, halogenated alkyl, halogenated aryl, and combinations thereof, said R* having up to 10 non-hydrogen atoms, and optionally, two R* group from Z* (when R* is not hydrogen), or an R* group from Z* and an R* group from Y form a ring system.

Most preferred complexes are amidosilane or amidoalkanediyl complexes wherein the metal is titanium.

Highly preferred diene groups are l,4-diphenyl-l,3-butadiene, 1,3-pentadiene, 1,4-dibenzyl-1,3-butadiene, 3-methyl-1,3-pentadiene Illustrative but not limiting examples of complexes preferred are (tert-10 butylamido) (tetramethyl-ri5-cyclopentadienyl) dimethylsilane titanium (II) 1,4-diphenyl-1,3-butadiene, (tert-butylamido) (tetramethyl-r|5-cyclopentadienyl) dimethyl silane titanium (II) 1,3-pentadiene, (tert-butylamido) (2-methylmdenyl) dimethylsilanetitanium (II) 1,4-15 diphenyl-l,3-butadiene The complexes may be rendered catalytically active by combination with an activating cocatalyst or by use of an activating technique Suitable activating cocatalysts for use herein include polymeric or oligomeric alumoxanes, especially methylalumoxane, trnsobutyl aluminium modified methylalumoxane, or 20 dnsobutylalumoxane, strong Lewis acids, such as, Cmo hydrocarbyl substituted Group 13 compounds, especially tn(hydiocarbyl)aluminiuin- or tri(hydrocarbyl)boron compounds and halogenated derivatives thereof, having from 1 to 10 carbons in each hydrocarbyl or halogenated hydrocarybl group, more especially perfluonnated tn(aryl)boron compounds, and most especially 25 tns(pentafluorophenyl)borane, nonpolymeric, inert, compatibel, noncoordinating, ion forming compounds (including the use of such compounds under oxidising conditions), bulk electrolysis and combinations of the foregoing activating cocatalysts and techniques The foregoing activating cocatalysts and activating techniques have been previously taught with respect to such metal complexes m the 30 aforementioned WO 95/00526 A particulaily preferred activator is tns (pentafluorophenyl) boron Suitable ion forming compounds useful as cocatalysts comprise a cation which is a Bronsted acid capable of donating a proton, and an inert, compatible, noncoordinating, anion. A- Preferred anions ai e those containing a single 35 coordination complex comprising a charge-bearing metal or metalloid core which Printed from Mimosa anion is capable of balancing the charge of the active catalyst species (the metal cation) which is formed when the two components are combined. Also, said anion should be sufficiently-labile to be displaced by olefinic, diolefinic and acetylenically unsaturated compounds or other neutral Lewis bases such as ethers or nitriles.

Suitable metals include, but are not limtied to, aluminium, gold and platinum Suitable metalloids include, but are not limited to, boron, phosphorus, and silicon Compounds containing anions which comprise coordination complexes containing a single metal or metalloid atom are available commerically particularly such compounds containing a single boron atom in the anion portion 10 Preferred boron compounds are salts such as tetrakis (pentafluorophenyl) borate tnethylammonium tetrakis (pentafluorophenyl) borate N,N-dimethylanilinium tetrakis (pentafluorophenyl) borate N,N-diethylanilinium tetrakis (pentafluorophenyl) borate 1 5 Other constrained geometry complexes suitable for use in the process of the present invention are those in which the metal is in a higher valency state Such complexes are disclosed in EP 416815 and WO 91/04257 both of which are incorporated herein by reference The complexes have the general formula Cp' \ (X), wherein Cp* is a single ri5-cyclopentadienyl or ^-substituted cyclopentadienyl group optionally covalently bonded to M through -Z-Y- and corresponding to the formula R / Printed from Mimosa 501653 wherein each R occurrence is hydrogen or a moiety selected from halogen, alkyl, aryl, haloalkyl, alkoxy, aryloxy, silyl groups, and combinations thereof of up to 20 non-hydrogen atoms, or two or more R groups together form a fused ring system; M is zirconium, titanium or hafnium bound in an r\5 bonding mode to the 5 cyclopentadienyl or substituted cyclopentadienyl group and is in a valency state of +3 or +4 X each occurrence is hydride or a moiety selected from halo, alkyl, aryl, silyl, germyl, aryloxy, alkoxy, amide, siloxy, and combinations thereof (e g. haloalkyl, haloaryl, halosilyl, alkaryl, aralkyl, silylalkyl, aryloxyaryl, and 10 alkyoxyalkyl, amidoalkyl, amidoaryl) having up to 20 non-hydrogen atoms, and neutral Lewis base ligands having up to 20 non-hydrogen atoms, n is 1 or 2 depending on the valence of M, Z is a divalent moiety comprising oxygen, boron, or a member of Group 14 of the Periodic Table of the Elements, Y is a linking group covalently bonded to the metal comprising nitrogen, phosphorus, oxygen or sulfur, or optionally Z and Y together form a fused ring system Most preferred complexes are those wherein Y is a nitrogen or phosphorus containing group corresponding to the formula (-NR') or (-PR^) wherein R^ is 20 Cj-Cjq alkyl or C6-Ciq aryl and wherein Z is SiR"2, CR"2, SiR"2 SiR"2, CR'-CR" or GeR"? in which R" is hydrogen or hydrocarbyl Most preferred complexes are those wherein M is titanium or zirconium Illustrative, but not limiting examples of suitable complexes are (tert-butylamido) (tetramethyl-ri5-cyclopentadienyl) dimethyl silanetitanium dimethyl, 25 (tert-butylamido) dibenzyl (tetramethyl-r)5-cyclopendienyl) silane zirconium dibenzyl, (benzylamido) dimethyl (tetramethyl-r|5-cyclopentadienyl) silane titanium dichloride, (phenylphosphido) dimethyl (tetramethyl-ri5-cyclopentadienyl) silane zirconium dibenzyl and the like These complexes are also rendered catalytically active by combination with 30 similar activating cocatalysts as described above. Suitable cocatalysts include aluminoxanes, especially methylaluminoxane (MAO) or strong Lewis acids eg tri (hydrocarbyl) boron compounds or halogenated derivatives Particularly suitable as an activator is tns (pentafluorophenyl) boron These complexes may also be rendered active by combination with ion 35 forming compounds as described above INTELLECTUAL PROPERTY OFFICE OF N.Z. - 4 SEP 2001 RECEIVE* 501653 The transition metal complex suitable for use in the process of the present invention may also be a traditional bis (cyclopentadienyl) transition metal complex as disclosed in EP 12-9368 or EP 206794 Such complexes may be represented by the formula CP2MX2 wherein M is Zr, Ti or Hf and X represents an anionic ligand Such complexes may advantageously comprise cyclopentadienyl rings which are substituted by hydrocarbyl groups for example alkyl Examples of such complexes are bis (cyclopentadienyl) zirconium dichloride or bis (tetramethylcyclopentadienyl) zirconium dichloride Also suitable are constrained geometry complexes wherein the substituents on the cyclopentadienyl rings form a bridge between the two rings for example complexes disclosed in EP 659773 A particularly suitable complex is ethylene bis (indenyl) zirconium dichloride The above bis (cyclopentadienyl) transition metal complexes are most suitably activated by alumoxanes in particular methyl alumoxane.

Another type of constrained geometry complex suitable for use in the process of the present invention are bis (cyclopentadienyl) diene complexes as disclosed in WO 96/04920, incorporated herein by leference Such complexes may be represented by the formula M-D R" R" wherein: M is titanium, zirconium or hafnium in the +2 or +4 formal oxidation state.

R' and R" in each occurrence are independently selected from the group consisting of hydrogen, hydrocarbyl, silyl, germyl, cyano, halo and combinations thereof, said R' and R" having up to 20 non-hydrogen atoms each, or adjacent R' groups and/or adjacent R" groups (when R' and R" are not hydrogen atoms each, INTELLECTUAL PROPERTY OFFICE OF N.Z. -4 SEP 2001 RECEIVED WO 99/00431 PCT/GB97/01730 9 or adjacent R' groups and/or adjacent R" groups (when R' and R" are not hydrogen, halo or cyano) together form a divalent derivative thereby forming a fiised ring system, E is silicon, germanium or carbon, x is an integer from 1 to 8, R'" independently each occurrence is hydrogen or a group selected from silyl, hydrocarbyl, hydrocarbyloxy and combinations thereof, or two R1" groups together form a ring system, said R'" having up to 30 carbon or silicon atoms, and D is a stable, conjugated diene, optionally substituted with one or more 10 hydrocarbyl groups, silyl groupls, hydrocarbylsilyl groups, silylhydrocarbyl groups, or mixtures thereof, said D having from 4 to 40 nonhydrogen atoms Particularly suitable are complexes in which M is zirconium and E is carbon Such complexes may suitably be activated by the cocatalysts described 1 5 above A particularly preferred cocatalyst is tri (pentafluorophenyl) boron The molai ratio of complex to activator employed in the process of the present invention may be in the range I 10000 to 100 1 A preferred range is from 1 5000 to 10 1 and is most prefened in the range 1 10 to 1 1 The complexes accoiding to the process of the present invention for use in 20 the gas phase are supported Typically the support can be any organic or inorganic inert solid particularly porous supports such as talc, inorganic oxides and resinous support materials such as polyolefins Suitable inorganic oxide materials which may be used include Group 2, 13, 14 oi 15 metal oxides such as silica, alumina, silica-25 alumina and mixtures thereof Other inorganic oxides that may be employed either alone or in combination with the silica, alumina or silica-alumina are magnesia, titama or zirconia Other suitable support materials may be employed such as finely divided polyolefins such as polyethylene The most prefeired suppoit material for use with the supported catalysts 30 according to the process of the present invention is silica Suitable silicas include Crossfield ES70 and Davidson 948 silicas It is preferable that the silica is dried before use and this is typically carried out by heating at elevated temperatures for example betweeen 200 and 850 deg C In a preferred piotocol the supported catalyst may be prepared by addition 35 of a solution of the activator in a suitable solvent to a slurry of activated silica Printed from Mimosa 50 1 65 3 treated with a trialkylaluminium compound followed by addition of a solution of the transition metal complex in the same solvent Alternatively the complex may be added to the trialkylaluminium treated silica before addition of the activator.

A suitable solvent for the preparation of the supported catalyst is toluene. 5 Suitable trialkylaluminium compounds are trimethylaluminium (TMA), triethlyaluminium(TEA) or triisobutylaluminium (TIBAL).

Both the first stage and the second stage may be performed in an agitated dry phase reactor or in a fluidised bed reaction Alternatively the prepolymerised catalyst when recovered from the first 10 stage may be used in the second stage in a different gas phase reactor.

The most preferred gas phase reactor for the first stage of the present invention is a dry phase reactor in particularly an agitated dry phase reactor (ADPR) When a fluidised bed reactor is used a most preferred process is that 1 5 described in WO 94/28032 Other fluidised bed processes are decribed in EP 89691, WO 94/25495 and WO 94/25497 The present invention also provides for a method for preparing a prepolymerised catalyst Thus according to another aspect of the invention there is provided a 20 process for preparing a prepolymerised catalyst comprising prepolymerising ethylene or ethylene and are or more alpha olefins in the presence of a catalyst system comprising (a) a supported constrained geometry complex and (b) an activator, to form a prepolymerised catalyst and then recovering said prepolymerised catalyst The present invention may also be applicable to processes wherein the 25 prepolymerisation is carried out in the slurry phase Thus according to another aspect of the present invention there is provided a process for polymerising ethylene or ethylene and one or more alpha-olefins comprising' (1) ma first stage, prepolymerising ethylene or ethylene and one or more alpha-olefins at a temperature in the range from -20°C to +60°C in the presence of a catalyst system comprising (a) a supported constrained geometry complex and (b) an activator, to form a prepolymerised catalyst, (2) optionally, recovering the prepolymerised catalyst, (3) in a second stage, polymerising ethylene or ethylene and one or more alpha-35 olefins in the gas phase at a temperature in the range from 65°C to 100°C in the INTELLECTUAL PROPERTY OFFICE OF N.Z. - 4 SEP 2001 RECEIVED WO 99/00431 PCT/GB97/01730 11 presence of the prepolymerised catalyst The first stage may be carried out in a slurry reactor, an agitated dry phase reactor or in a fluidised bed reactor The prepolymerised catalyst may be recovered before the second stage or 5 used in-situ The process according to the present invention is suitable for use in the polymerisation of olefins in particularly in the homopolymensation of ethylene or the copolymerisation of ethylene with other alpha-olefins in particular those having from 3 to 10 carbon atoms Most preferred alpha-olefins are 1-butene, 1-hexene 10 and 4-methyl-1 -pentene Using the process according to the present invention polymers may be prepared having densities in the range from 0 905 to 0 960 g/cc and a melt index in the range 0 1 to 20 according to ASTM D1238 condition E (2 16 kg at 190 degC) The process of the pi esent invention will now be further illustrated by reference to the following examples The examples clearly show that by use of the prepolymerisation stage either separately or in-situ results in an improvement in the activity of the catalyst systems EXAMPLES 20 Example 1 Preparation of catalyst A lOg of Crosfield ES70 silica (activated at 500°C) were slurried in 50ml dry hexane 30ml of 0 5M TMA in hexane weie added (1 5 mmol Al/g silica), and the slurry agitated for 2 hours The treated silica was filtered and washed three times with 20ml of hexane, then dried in vacuo to a fine powder 25 2g of the TMA treated ES70 silica were slurried in 10ml of dry toluene 1 95ml of a 7 85 wt% solution of tns(pentafluorophenyl)boron in toluene were added, and the mixture shaken vigorously Then 0 62 ml of a 12 25 wt% solution of (tert-butylamido) (tetramethyl-r]" - cyclopentadienyl) dimethylsilanetitanium dimethyl in toluene were added The mixture was shaken well, and then the 30 solvent removed in vacuo at 20°C to give an yellow powder Example 2 Preparation of catalyst B 7 0kg of Crosfield ES70 silica (activated at 500°C.) were slurried in 100 litres of hexane 9 32 litres of 0 976M TEA in hexane were added (1 3 mmol Al/g silica), and the slurry agitated for 2 hours at 30°C The silica was allowed to settle, 35 and the supernatant hexane removed The silica was further washed with hexane, Printed from Mimosa 12 until the concentration of A1 in the washing had reached < 1 mmol Al/litre Then the silica was dried in vacuo at 40°C 3g of the TEA treated ES70 silica were slurried in 15ml of dry toluene 1 8ml of a 7 85wt% solution of tris(pentafluorophenyl)boron in toluene were 5 added, and the mixture shaken vigorously Then 0 62ml of a 10 7wt% solution of (tert-butylamido) (tetramethyl-r^-cyclopentadienyl) dimethylsilanetitanium penta-1,3-diene in toluene were added The mixture was shaken well, and then the solvent removed in vacuo at 20°C to give an olive green powder Example 3 Preparation of catalyst C 10 50g of the TEA treated ES70 silica, described for the preparation of Catalyst B, were slurried in 150ml of dry toluene 10 4ml of a 10 7wt% solution of (tert-butylamido) (tetramethyl-rf-cyclopentadienyl)dimethylsilanetitanium penta-1,3-diene in toluene were added, and the mixture shaken vigorously Then 29 4ml of a 7 85wt% solution of tns(pentafluorophenyl)boron in toluene were added The 15 mixture was shaken well, and then the solvent removed in vacuo at 40°C to give an olive green powder Example 4 Preparation of catalyst D lOg of the TEA treated ES70 silica, described for the preparation of Catalyst B, weie sluiried m 50ml of dry toluene 2 lml of a 10.7wt% solution of 20 (tert-butylamido) (tetramethyl-r^-cyclopentadienyl)dimethylsilanetitanium penta-1,3-diene in toluene were added, and the mixture shaken vigorously Then 5 9ml of a 7 85wt% solution of tns(pentafluoiophenyl)boron in toluene were added The mixture was shaken well, and then the solvent removed in vacuo at 20°C to give an olive green powder 25 Example 5 Preparation of catalyst E 45 76g of the TEA treated ES70 silica, described for the preparation of Catalyst B, were slurried in 225 ml of dry toluene 9 51ml of a 10 7wt% solution of (tert-butylamido)(tetramethyl-rf cyclopentadienyl)dimethylsilanetitanium penta-1,3-diene in toluene were added, and the mixture shaken well Then 26 9ml of a 30 7 85wt% solution of tris(pentafluorophenyl)boion m toluene were added The mixture was shaken well, and then the solvent removed in vacuo at 20°C to give an olive green powder Example 6 Preparation of prepolymer of catalyst C A 2 5 litre volume agitated dry phase leactor was baked out at 85°C under 35 a N2 purge It was cooled to 25°C, and 44 41 g of catalyst Catalyst C was added to Printed from Mimosa 13 the reactor It was pressurised to 0 47 bar with N2 The catalyst was agitated at 300rpm 0 30bar of C2H4 added, but this was quickly reduced to 0 08 bar to maintain the temperature of the reactor below 40°C This was continued for 126 minutes 34 Og of polymer-coated catalyst was recovered under N2 from the 5 reactor The polymer yield was 0 5g PE/g catalyst Example 7 Preparation of nrepolvmer of catalyst E A 2 5 litre volume agitated dry phase reactor was baked out at 85°C under a N2 purge It was cooled to 25°C, and 46 3g of catalyst Catalyst E was added to the reactor The reactor was pressurised to 1 05bar with N2 The catalyst was 10 agitated at 325rpm C2H4 was added to the reactor to give a total pressure of 1 25bar These conditions were maintained foi 3 75 hours Then the reactor was purged with N2, sealed under lbai N2 and left overnight for 16 hours C2H4 was again added to the reactor to give a total pressure of 1 25 bar 50 minutes after start-up, the pressure was increased to 1 30bar, and 5 hours after 15 start-up, increased further to 1 42 bar After 6 hours of polymerisation, the reactor was purged with N2 and 68 lg of polymer-coated catalyst was recovered under N2 The polymer yield was 2 Og PE/g catalyst Example 8 In-situ nrepolvnierisation of catalyst A 285g of NaCl was added to a 2 5 litre volume agitated dry phase reactor, 20 which had been previously baked out at 85°C under a N2 purge 1 67g of a TEA treated silica was added to the reactoi, and this was agitated for 15 minutes The temperature was reduced to 30°C, and 7 bar of C2H4 was admitted to the reactor Then a mixture of 0 22g of Catalyst A and 1 04g of a TEA treated silica was injected into-the reactor with high pressure N2 The pressure of C2H4 was 25 maintained at a pressure of 7 bar rapidly lamped at 80°C, and maintained at this temperature for the rest of the test The total polymerisation time was 120 minutes The reactor was vented and cooled, and 127g of polymer was recovered, giving a catalyst activity of 41 g/g h bai Comparative Example 1 30 A similar protocol of Example 8 was followed, except that the initial 30 minute period at 30°C was omitted A mixtuie of 0 243g of Catalyst A and 0 935g of a TEA ti eated silica was injected at a temperature of 70°C, then the temperature immediately increased to 80°C The run time was 100 minutes 64g of polymer was recoveied, giving a catalyst activity of 20 5g/g h bar 35 Comparison between example 8 and comparative example 1 demonstrates Printed from Mimosa WO 99/00431 PCT/GB97/01730 14 that the in situ prepolymerisation in the agitated dry phase reactor results in a greater homopolymerisation catalyst activity Examnle 9 In-situ prepolvmerisntion of catalyst B 320g of NaCI was added to a 2 5 litre volume agitated dry phase reactor, 5 which had been previously baked out at 85°C under a N2 purge 1 25g. of a TIBAL treated silica was added to the reactor, and this was agitated for 15 minutes The temperature was reduced to 30°C, and 1 bar of C2H4 was admitted to the reactor Then a mixture of 0 308g of Catalyst B and 0 825g of a TIBAL treated silica was injected into the reactor with high pressure N2 The pressure of C2H4 was 10 maintained at a pressure of l bar and 5 minutes, then the pressure increased rapidly to 6 5 bar and the temperature lamped rapidly to 70°C Then H2 and 1-hexene was admitted to the reactoi The temperature, C2H4 pressure and H2 and 1-hexene levels were maintained constant dunng the rest of the test The total polymerisation time was 191 minutes During the test, the average H2/C2H4 ratio 1 5 was 0 0046 and the average l-hexene/C2H4 ratio was 0 0052 The reactor was vented and cooled, and 278g of polymer was recovered, giving a catalyst activity of 43 6g/g h bar The polymei Ml216 was 7 41 and the density 0 926 g/ml Example 10 In-situ nrepolvinerisation of catalyst B 288g of NaCI was added to a 2 5 litre volume agitated dry phase reactor, 20 which had been previously baked out at 85°C under a N2 purge 1 30g of a TIBAL treated silica was added to the reactoi, and this was agitated for 15 minutes The temperatme was 1 educed to 30°C, and 1 bar of C2H4 was admitted to the reactor Then a mixture of 0 238g of Catalyst B and 0 725g of a TIBAL treated silica was injected into-the reactor with high piessuie N2 The pressure of C2H4 was 25 maintained at a pressure of 1 bar foi 5 minutes, then the pressure increased rapidly to 6 5 bar and the temperature lamped rapidly to 80°C Then H2 and 1-hexene were admitted to the reactor The temperature, C2H4 pressure and H2 and 1-hexene levels were maintained constant dunng the rest of the test The total polymerisation time was 116 minutes During the test, the average H2/C2H4 ratio 30 was 0 0052 and the aveiage 1 -hexene/C2H4 ratio was 0 0049 The reactor was vented and cooled, and 99g of polymer was recovered, giving a catalyst activity of 33 lg/g h bar The polymei M12 Kl was 2 7 and the density 0 9185 g/ml Example 11 In-situ prepolymerisation of catalyst B 305g of NaCI was added to a 2 5 litre volume agitated dry phase reactor, 35 which had been previously baked out at 85°C under a N2 purge 1 20g of a TIBAL Printed from Mimosa WO 99/00431 PCT/GB97/01730 treated silica was added to the reactor, and this was agitated for 15 minutes The temperature was reduced to 30°C, and 1 bar of C2H4 was admitted to the reactor Then a mixture of 0 23 lg of Catalyst B and 0 912g of a TIBAL treated silica was injected into the reactor with high pressure N2 The pressure of C2H4 was 5 maintained at a pressure of 1 bar for 5 minutes, then the pressure increased rapidly to 6 5 bar and the temperature ramped rapidly to 70°C Then H2 and 1-hexene were admitted to the reactor The temperature C2H4 pressure and H2 and 1-hexene levels were maintained constant during the rest of the test The total polymerisation time was 189 minutes During the test, the average H2/C2H4 ratio 10 was 0 00395 and the average l-hexene/C2H4 ratio was 0 0048 The reactor was vented and cooled, and 168g of polymer was recovered, giving a catalyst activity of 35 5g/g h bai The polymei Ml2 k, was 1 7 and the density 0 9295 g/ml Comparative Example 2 A similai protocol to Examples 9, 10 and 11 were followed, except that the 1 5 initial low temperature and pressuie start-up was omitted Thus 344g of NaCI was added to a 2 5 litre volume agitated dry phase reactor, which had been previously baked out at 85°C undei a N2 purge 1 30g of a TIBAL treated silica was added to the reactor, and this was agitated for 15 minutes The reactor was cooled to 70°C, and pressurised to 6 5 bar C2H4 Then H2 and 1-hexene were admitted to the 20 reactor A mixtui e of 0 213g of Catalyst C and 0 781 g of a TIBAL treated silica was injected into the reactoi with high pressure N2 The temperature, C2H4 pressure and H2 and 1-hexene levels weie maintained constant during the rest of the test The total polymerisation time was 166 minutes During the test, the average H2/C2H4 ratio was 0 0038 and the average l-hexene/C2H4 ratio was 0 0053 The 25 reactor was vented and cooled, and 10 ig of polymer was recovered, giving a catalyst activity of 26 3g/g h bar Companson between examples 9, 10 and 11 with comparative example 2 demonstrates that the in situ prepolymerisation in the agitated dry phase reactor results in a gieatei copolymeiisation catalyst activity 30 Example 12 Polymerisation with prepolviner of catalyst C 305g of NaCI was added to a 2 5 litre volume agitated dry phase reactor, which had been previously baked out at 85° under a N2 purge 1 225g of a TIBAL treated silica was added to the leactor, and this was agitated for 15 minutes The reactor was cooled to 70°C, and piessurised to 6 5 bar C2H4 The H2 and 1-hexene 35 were admitted to the leactoi A mixture of 0 956g of prepolymer of catalyst C and Printed from Mimosa 16 0 745g of a TIBAL treated silica was injected into the reactor with high pressure N2 The temperature, C2H4 pressure and H2 and 1-hexene were maintained constant during the rest of the test The total polymerisation time was 127 minutes During the test, the average H2/C2H4 ratio was 0 00415 and the average 5 l-hexene/C2H4 ratio was 0 0057 The reactor was vented and cooled and 250g of polymer was recovered, giving an activity of 28 8g/g h bar based on the mass of the original catalyst Example 13 Polymerisation with prepolymer of catalyst E 292g of NaCI was added to a 2 5 litre volume agitated dry phase reactor, 10 which had been pieviously baked out at 85°C under a N2 purge 1 223g of a TIBAL treated silica was added to the reactor, and this was agitated for 15 minutes The reactor was cooled to 70°C, and pressurised to 6 5 bar C2H4 Then H2 and 1-hexene were admitted to the reactor A mixture of 1 02g of prepolymer of catalyst E and 0 744g of a TIBAL tieated silica was injected into the reactor 15 with high piessuie N2 The temperatuie, C2H4 pressure and H2 and l-hexene levels wei e maintained constant during the rest of the test The total polymerisation time was 127 minutes Dunng the test, the average H2/C2H4 ratio was 0 0044 and the average 1-hexene C2H4 latio was 0 0048 The reactor was vented and cooled, and 175g of polymer was tecoveied, giving an activity of 37 4g/g h bar based on the 20 mass of the original catalyst Example 14 Polymerisation with nrenolvmer of catalyst E 352g of NaCI was added to a 2 5 litre volume agitated dry phase reactor, which had been previously baked out at 85°C under a N2 purge 1 20g of a TIBAL treated silica was added to the reactor, and this was agitated for 15 minutes The 25 reactor was cooled to 60°C, and pressunsed to 6 5 bar C2H4 Then H2 and 1-hexene were admitted to the reactor A mixtui e of 0 915g of prepolymer of catalyst E and 0 8g of a TIBAL treated silica was injected into the reactor with high pressure N2 The temperatui e was taken rapidly to 70°C The temperature, C2H4 pressure and H2 and 1-hexene levels were maintained constant during the rest 30 of the test The total polymensation time was 87 minutes During the test, the average H2/C2H4 ratio was 0 0044 and the average l-hexene/C2H4 ratio was 0 0055 The ieactor was vented and cooled, and 128g of polymer was recovered, giving an activity of 44 5 g/g h bar based on the mass of the original catalyst Examples 13 and 14 and comparative example 2 start from the same basic 35 catalyst formulation (see above) They demonstrate that the effect of Printed from Mimosa

Claims (16)

1. WO 99/00431

   PCT/GB97/01730

   prepolymerising the catalyst prior to injection into the reactor results in improved catalyst activity

   5

   10

   15

   20

   25

   30

   35

   Printed from Mimosa

   WO 99/00431 PCT/GB97/01730

   18

   501653

   What we claim is:

   1 A process for polymerising ethylene or copolymensing ethylene and one or more alpha-olefins in the gas phase comprising -

   (1) in a first stage prepolymerising ethylene oi ethylene and one or more alpha-olefins in the gas phase at a temperature in the range 20 to 70°C in the

   5 presence of a catalyst system comprising (a) a supported constrained geometry complex and (b) an activator,

   (2) optionally, recovering the prepolymerised catalyst, and

   (3) in a second stage polymerising ethylene or ethylene and one or more alpha-olefins in the gas phase at a temperature in the range 65 to 100 °C in the

   10 piesence of said prepolymerised catalyst
2. 2 A piocess according to claim l wherein the first stage is carried out at a temperatuie in the range 25-40°C and the second stage at a temperature in the range 70-85°C
3. 3 A process according to claim 1 or 2 wherein the first stage is carried out at 15 a pressure in the range 0 l to 10 bar
4. 4 A process according to any of the preceeding claims wherein the first stage is performed in the dry phase
5. 5 A process according to claim 4 wherein the first stage is performed using an agitated dry phase ieactoi.

   20
6. 6 A process according to any of the preceeding claims wherein both stages are earned out m a single gas phase reactor
7. 7. A process according to any of the preceeding claims wherein the constrained geometry complex has the formula: -

   25

   INTELLECTUAL PROPERTY OFFICE OF N.Z.

   - 4 SEP 2001

   RECEIVED

   WO 99/00431

   PCT/GB97/01730

   19

   501653

   wherein

   R1 each occurrence is independently selected from hydrogen, hydrocarbyl, 1 0 silyl, germyl, halo, cyano, and combinations thereof, said R1 having up to 20 non hydrogen atoms, and optionally, two R' groups (where R' is not hydrogen, halo or cyano) together form a divalent derivative thereof connected to adjacent positions of the cyclopentadienyl ring to form a fused ring structure,

   X is a neutral r^- bonded diene group having up to 30 non-hydrogen 1 5 atoms, which forms a 7r-complex with M,

   Y is -0-, -S-, -NR*-, -PR*-,

   M is titanium or zirconium in the +2 formal oxidation state,

   Z* is SiR*2, CR*2, SiR*2SiR*2, CR*2CR*2, CR*=CR*, CR2SiR*2, or GeR*2, wherein

   20 R* each occurrence is independently hydrogen, or a member selected from hydrocarbyl, silyl, halogenated alkyl, halogenated aryl, and combinations thereof,

   said R* having up to 10 non-hydrogen atoms, and optionally, two R* group from Z* (when R* is not hydrogen), or an R* group from Z* and an R* group from Y form a nng system ^25
8. 8 A process according to claim 7 wherein the complex is -

   (tert-butylamido) (tetramethyl-n^-cyclopentadienyl) dimethyl silane titanium (II) 1,3-pentadiene,
9. 9. A process according to claims 1-6 wherein the constrained geometry complex has the formula:-

   30 y

   Cp*

   35

   (X)

   n

   INTELLECTUAL PROPERTY OFFICE OF N.Z.

   - 4 SEP 2001

   RECEIVED

   WO 99/00431

   PCT/GB97/01730

   20

   501653

   wherein

   Cp* is a single r\5-cyclopentadienyl or r|5-substituted cyclopentadienyl group optionally covalently bonded to M through -Z-Y- and corresponding to the formula

   10

   R

   15

   20

   25

   30

   35

   wherein each R occurrence is hydrogen or a moiety selected from halogen, alkyl,

   aryl, haloalkyl, alkoxy, aiyloxy, silyl gioups, and combinations thereof of up to 20 non-hydrogen atoms, or two or more R groups together form a fused ring system,

   M is zirconium, titanium or hafnium bound in an ri5 bonding mode to the cyclopentadienyl or substituted cyclopentadienyl group and is in a valency state of +3 or +4

   X each occunence is hydnde or a moiety selected from halo, alkyl, aryl,

   silyl, germyl, aryloxy, alkoxy, amide, siloxy, and combinations thereof (e g haloalkyl, haloaryl, halosilyl, alkaryl, aralkyl, silylalkyl, aryloxyaryl, and aikyoxyalkyl, amidoalkyl, amidoaryl) having up to 20 non-hydrogen atoms, and neutral Lewis base ligands having up to 20 non-hydrogen atoms,

   n is 1 or 2 depending on the valence of M,

   Z is a divalent moiety comprising oxygen, boron, or a member of Group 14 of the Periodic Table of the Elements,

   Y is a linking group covalently bonded to the metal comprising nitrogen, phosphoais. oxygen or sulfur, or optionally Z and Y together form a fused ring system
10. 10 A piocess accoiding to claim 9 wherein the complex is (tert-butylamido) (tetramethvl-rP - cyclopentadienyl) dimethylsilanetitanium dimethyl
11. 1 1 A piocess accoiding to any of the preceeding claims wherein the complex is

    INTELLECTUAL PROPERTY OFFICE OF N.Z.

    " < SEP 2001

    RECEIVED

    WO 99/00431 PCT/GB97/01730

    21

    supported on silica
12. 12 A process according to claim ! 1 wherein the silica is pretreated with a tri alkylaluminium compound
13. 13. A process according to any of the preceeding claims wherein the activator 5 is tris(penta flurophenyl) boron
14. 14 A process according to any of the preceeding claims wherein the ratio of complex to activator is in the range 1 10,000 to 100 1
15. 15 A process according to claim 14 wherein the ratio is in the range 1.10 to 1 1

    10
16. 16. A process for preparing a prepolymerised catalyst comprising prepolymerising ethylene or ethylene and at one or more alpha olefins at a temperature in the range 20°C-70°C in the presence of a catalyst system comprising (a) a supported constrained geometry complex and (b) an activator, to form a prepolymerised catalyst and then recovering said ^ g prepolymerised catalyst.

    17. A process according to claim 16 performed in the dry phase

    18. A process for polymerising ethylene or ethylene and one or more alpha-olefins comprising:

    (1) in a first stage carried out in the slurry phase, prepolymerisation ethylene or

    20

    ethylene and one or more alpha-olefins at a temperature in the range from —20°C to +60°C in the presence of a catalyst system comprising (a) a supported constrained geometry complex and (b) an activator, to form a prepolymerised catalyst;

    (2) optionally, recovering the prepolymerised catalyst;

    25 (3) in a second stage, polymerising ethylene or ethylene and one or more alpha-olefins in the gas phase at a temperature in the range from 65°C to 100°C in the presence of the prepolymerised catalyst.

    19. A process according to any of the preceeding claims wherein the alpha-olefins are ^ q 1 -butene, 1 -hexene or 4-methyl-1 -pentene.

    20. A process according to claims 1, 16, or 18 substantially as herein described with reference to any one of Examples 1 to 14.

    21. A process according to any one of claims 1 to 19 substantially as herein described.

    BP CHEMICALS LIMITED

    By its Attorneys

    BALDWIN SHELSTON WATERS

    501653

    35

    4 SEP 2001

    .received