Classifications

• • 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
• • 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
  • C08F4/00—Polymerisation catalysts
  • C08F4/42—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors
  • C08F4/44—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides
  • C08F4/60—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides together with refractory metals, iron group metals, platinum group metals, manganese, rhenium technetium or compounds thereof
  • C08F4/62—Refractory metals or compounds thereof
  • C08F4/64—Titanium, zirconium, hafnium or compounds thereof
  • C08F4/659—Component covered by group C08F4/64 containing a transition metal-carbon bond
  • C08F4/65912—Component covered by group C08F4/64 containing a transition metal-carbon bond in combination with an organoaluminium compound
• • 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
  • C08F4/00—Polymerisation catalysts
  • C08F4/42—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors
  • C08F4/44—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides
  • C08F4/60—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides together with refractory metals, iron group metals, platinum group metals, manganese, rhenium technetium or compounds thereof
  • C08F4/62—Refractory metals or compounds thereof
  • C08F4/64—Titanium, zirconium, hafnium or compounds thereof
  • C08F4/659—Component covered by group C08F4/64 containing a transition metal-carbon bond
  • C08F4/65916—Component covered by group C08F4/64 containing a transition metal-carbon bond supported on a carrier, e.g. silica, MgCl2, polymer
• • 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
  • C08F4/00—Polymerisation catalysts
  • C08F4/42—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors
  • C08F4/44—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides
  • C08F4/60—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides together with refractory metals, iron group metals, platinum group metals, manganese, rhenium technetium or compounds thereof
  • C08F4/62—Refractory metals or compounds thereof
  • C08F4/64—Titanium, zirconium, hafnium or compounds thereof
  • C08F4/659—Component covered by group C08F4/64 containing a transition metal-carbon bond
  • C08F4/6592—Component covered by group C08F4/64 containing a transition metal-carbon bond containing at least one cyclopentadienyl ring, condensed or not, e.g. an indenyl or a fluorenyl ring

Definitions

• the present invention relates to a process for polymerizing olefins and in particular to a process for the polymerization of olefins using a supported catalyst composition comprising a transition metal compounds and an activator comprising an aluminoxane and an organoboron compound.
• the process is particularly suitable for operation in the gas phase and preferred transition metal compounds are metallocene complexes.
• the process according to the present invention is also particularly suitable for the preparation in the gas phase of copolymers having an improved melt strength.
• Metallocene catalysts offer the advantage of generally higher activity than traditional Ziegler catalysts and are usually described as catalysts which are single-site in nature. Because of their single-site nature the polyolefin copolymers produced by metallocene catalysts often are quite uniform in their molecular structure. For example, in comparison to traditional Ziegler produced materials, they have relatively narrow molecular weight distributions (MWD) and narrow Short Chain Branching Distribution (SCBD). Although certain properties of metallocene products are enhanced by narrow MWD, difficulties are often encountered in the processing of these materials into useful articles and films relative to Ziegler produced materials. In addition, the uniform nature of the SCBD of metallocene produced materials does not readily permit certain structures to be obtained.
• MWD molecular weight distributions
• SCBD Short Chain Branching Distribution
• the metallocene complex comprises a bis(cyclopentadienyl) zirconium complex for example bis(cyclopentadienyl) zirconium dichloride or bis(tetramethylcyclopentadienyl) zirconium dichloride.
• bis(cyclopentadienyl) zirconium complex for example bis(cyclopentadienyl) zirconium dichloride or bis(tetramethylcyclopentadienyl) zirconium dichloride. Examples of such complexes may be found in EP 129368, EP 206794, and EP 260130.
• the metal complex is used in the presence of a suitable activator.
• the activators most suitably used with such metallocene complexes are aluminoxanes, most suitably methyl aluminoxane (MAO).
• Other suitable activators are boron compounds, in particular perfluorinated boron compounds.
• activators are aluminoxanes, in particular methyl aluminoxane or compounds based on boron compounds.
• boranes for example tris(pentafluorophenyl) borane, or borates such as trialkyl-substituted ammonium tetraphenyl- or tetrafluorophenyl-borates.
• Catalyst systems incorporating such borate activators are described in EP 561479, EP 418044 and EP 551277.
• metallocene complexes When used for the gas phase polymerisation of olefins, metallocene complexes may typically be supported for example on an inorganic oxide such as silica. Such supports may be typically dehydrated by calcining before use or may be pretreated with an organoaluminium compound to passivate the surface of the silica.
• WO 95/00526 describes in general terms the use of the reduced oxidation state monocyclopentadienyl complexes with both aluminoxane and borane activators.
• supported catalyst systems are described, all the examples of gas phase polymerisations with supported catalysts are limited to the use of a single activator, typically tris(pentafluorophenyl) borane.
• WO 99/15534 describes the combination of aluminoxanes with a fluoroaryl ligand source such as tris(pentafluorophenyl) borane as activators for metallocene complexes.
• a fluoroaryl ligand source such as tris(pentafluorophenyl) borane
• the activator combinations may be used for the gas phase polymerisation of olefins.
• the gas phase examples in the reference utilise silica supports that have been calcined prior to contact with the activator components.
• WO 00/15672 describes functionalized catalyst supports having chemically bonded aluminium containing groups prepared by the combination of supports having reactive functional groups with a source of aluminium.
• aluminoxane/borane activator combinations are supported on silica which has been dehydrated.
• an olefin polymerisation process comprising contacting one or more olefin monomers with a supported catalyst composition prepared by contacting
• an activator comprising (i) an aluminoxane and (ii) an organoboron compound,
• Aluminoxanes are well known as activators for metallocene comlexes.
• Suitable aluminoxanes for use in the process of the present invention, include polymeric or oligomeric aluminoxanes in particular methyl aluminoxane (MAO).
• MAO methyl aluminoxane
• the aluminoxanes suitable for use in the present invention may be commercially available material or may be such commercially available material that has been dried under vacuum prior to its use for the preparation of the supported catalyst compositions.
• Preferred organoboron compounds are triarylboron compounds, in particular perfluorinated triarylboron compounds.
• the most preferred organoboron compound is tris(pentafluorophenyl) borane (FAB).
• aluminoxanes and organoboron compounds suitable for use in the process of the present invention are well known in the art and are described for example in EP 277003, EP 206794, and the aforementioned WO 95/00526.
• the ratio of boron/transition metal in the supported metallocene complexes of the present invention is typically in the range 0.1 to 10 and most preferably in the range 1 to 4.
• the support may be any organic or inorganic inert solid. However particularly porous supports such as talc, inorganic oxides and resinous support materials such as polyolefins, which have well-known advantages in catalysis, are preferred. Suitable inorganic oxide materials which may be used include Group 2, 13, 14 or 15 metal oxides such as silica, alumina, silica-alumina and mixtures thereof.
• inorganic oxides that may be employed either alone or in combination with the silica, alumina or silica-alumina are magnesia, titania or zirconia.
• suitable support materials may be employed such as finely divided polyolefins such as polyethylene.
• the most preferred support material for use with the supported catalysts according to the process of the present invention is silica.
• Suitable silicas include Crossfield ES70 and Davidson 948 silicas.
• the support material may be subjected to a heat treatment to reduce the water content or the hydroxyl content of the support material.
• a heat treatment to reduce the water content or the hydroxyl content of the support material.
• the support material may be subjected to treatment at 100° C. to 1000° C. and preferably at 200 to 850° C. in an inert atmosphere under reduced pressure, for example, for 5 hrs.
• the support material is pretreated with an organoaluminium compound, for example a trialkylaluminium compound, at a temperature of ⁇ 20° C. to 150° C. and preferably at 20° C. to 100° C.
• organoaluminium compound for example a trialkylaluminium compound
• the support material is contacted with the organoaluminium compound at room temperature in a suitable solvent, for example hexane.
• Preferred trialkylaluminium compounds are triethylaluminium and triisobutylaluminium.
• the pretreated support is preferably recovered before use in the preparation of the supported catalysts used in the process of the present invention.
• the transition metal compound may be any suitable compound known in the art for use as a catalyst component for the polymerisation of olefins.
• the preferred transition metal compounds are metallocene complexes.
• the metallocene complex comprises a bis(cyclopentadienyl) zirconium complex for example bis(cyclopentadienyl) zirconium dichloride or bis(tetramethylcyclopentadienyl) zirconium dichloride.
• bis(cyclopentadienyl) zirconium complex for example bis(cyclopentadienyl) zirconium dichloride or bis(tetramethylcyclopentadienyl) zirconium dichloride. Examples of such complexes may be found in EP 129368, EP 206794, and EP 260130.
• metallocene complexes are monocyclopentadienyl complexes. Such complexes have been referred to as ‘constrained geometry’ complexes and examples of these complexes may be found in EP 416815 or EP 420436.
• R′ each occurrence is independently selected from hydrogen, hydrocarbyl, silyl, germyl, halo, cyano, and combinations thereof, said R′ having up to 20 nonhydrogen 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 4 bonded diene group having up to 30 non-hydrogen atoms, which forms a ⁇ 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* 2 SIR* 2 , CR* 2 CR* 2 , CR* ⁇ CR*, CR* 2 SIR* 2 , or
• GeR* 2 wherein:
• 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* groups from Z* (when R* is not hydrogen), or an R* group from Z* and an R* group from Y form a ring system,
• Suitable X groups include s-trans- 4 -1,4-diphenyl-1,3-butadiene, s-trans- 4 -3-methyl-1,3-pentadiene; s-trans- 4 -2,4-hexadiene; s-trans- 4 -1,3-pentadiene; s-trans- 4 -1,4-ditolyl-1,3-butadiene; s-trans- 4 -1,4bis(trimethylsilyl)-1,3-butadiene; s-cis- 4 -3-methyl-1,3-pentadiene; s-cis- 4 -1,4-dibenzyl-1,3-butadiene; s-cis- 4 -1,3-pentadiene; s-cis- 4 -1,4-bis(trimethylsilyl)-1,3-butadiene, said s-cis diene group forming a ⁇ -complex as
• R′ is hydrogen, methyl, ethyl, propyl, butyl, pentyl, hexyl, benzyl, or phenyl or 2 R′ groups (except hydrogen) are linked together, the entire C 5 R′ 4 group thereby being, for example, an indenyl, tetrahydroindenyl, fluorenyl, terahydrofluorenyl, or octahydrofluorenyl group.
• Highly preferred Y groups are nitrogen or phosphorus containing groups containing a group corresponding to the formula —N(R′′)—or —P(R′′) ⁇ wherein R′′ is C 1-10 hydrocarbyl.
• Most preferred complexes are amidosilane—or amidoalkanediyl complexes.
• a particularly preferred complex for use in the present invention is (t-butylamido) (tetramethyl- 5 -cyclopentadienyl) dimethyl silanetitanium - 4 -1,3-pentadiene.
• the support may be pretreated with the aluminoxane before contact with the other catalyst components.
• the preferred supported catalyst systems for use in the process of the present invention may be prepared by
• Suitable transition metal compounds are as hereinbefore described but preferably the transition metal compound is a monocyclopentadienyl metallocene complex.
• the supported catalyst compositions of the present invention may be suitable for use in any polymerisation process for example solution, slurry or gas phase.
• the preferred process is a gas phase process.
• the preferred gas phase process takes place continuously in a fluidised bed.
• the continuous polymerisation is effected in the gas phase at elevated temperature in the presence of a fluidised bed of polymer particles and continuous recycle of unreacted monomer(s) around a loop joining the inlet and outlet of the reactor containing the fluidised bed.
• a fluidised bed of polymer particles and continuous recycle of unreacted monomer(s) around a loop joining the inlet and outlet of the reactor containing the fluidised bed.
• the process of the present invention is suitable for the polymerisation of ethylene or the copolymerisation of ethylene with one or more alpha-olefins having from three to twenty carbon atoms.
• the alpha-olefin has between three and ten carbon atoms most preferably three and eight.
• Examples of the most preferred alpha olefins include 1-butene, 1-hexene, 4-methyl-l-pentene, 1-octene.
• the process of the present invention is most particularly directed to the preparation of copolymers of ethylene with alpha-olefins having at least 6 carbon atoms in particular to copolymers of ethylene with 1-hexene or 4-methyl-1-pentene.
• the polymers prepared according to the process of the present invention have a molecular weight distribution (Mw/Mn) value of less than 7 and most preferably less than 5.
• the preferred molecular weight distribution is in the range 2.5 to 7.0 and preferably in the range 3.0 -5.0.
• the polymers prepared according to the process of the present invention exhibit an improved melt strength and typically have values in the range 3 -12 cN and preferably in the range 6 -9 cN.
• copolymers are preferably prepared by use of a supported metallocene catalyst system as hereinbefore described.
• the preferred catalyst system for this aspect of the present invention is a monocyclopentadienyl complex as hereinbefore described.
• the preferred process for the preparation of such copolymers is a gas phase process.
• Examples 1 -4 illustrate the preparative routes to the supported catalyst compositions used in the process of the present invention.
• Examples 5 -9 illustrate the use of the supported catalyst compositions for the gas phase polymerisation of olefins.
• melt flow rate (MFR) of the polymers was measured under conditions which conform to ISO 1133 (1991) and BS 2782:PART 720A:1979 procedures.
• the weight of polymer extruded through a die of 2.095 mm diameter, at a temperature of 190° C., during a 600 second time period and under a standard load of 2.16 kg is recorded.
• the second experiment was carried out at the lowest test temperature (eg 170° C.) with a high applied frequency of 100 rad/s. This is to ensure that the selected applied strain is well within the linear viscoselastic region of the polymer so that the oscillatory Theological measurements do not induce structural changes to the polymer during testing. This procedure was carried out for all the samples.
• Shift Mode 2D (ie horizontal & vertical shifts)
• the melt strength of the polymer is measured at 190° C., using a Göttfert Rheotens extensional rheometer in conjunction with a Rosand RH 7 Capillary Rheometer. This is achieved by extruding the polymer at a constant pressure (P) through a die of 1.5 mm diameter and 30 mm in length, with a 90° entry angle. Once a given extrusion pressure is selected, the piston of the capillary rheometer will travel through its 15 mm diameter barrel at a speed that is sufficient to maintain that pressure constant. The nominal wall shear rate ( ⁇ dot over ( ⁇ ) ⁇ ) for a given extrusion pressure can then be computed for the polymer at the selected pressure using the constant pressure ratio system of the rheometer.
• the extrudate is drawn with a pair of gear wheels at an accelerating speed (V).
• the acceleration ranges from 0.12 to 1.2 cm/s 2 depending on the flow properties of the polymer under test.
• the drawing force (F) experienced by the extrudate is measured with a transducer and recorded on a chart recorder together with the drawing speed.
• the maximum force at break is defined as melt strength (MS) at a constant extrusion pressure (P) or at its corresponding extrusion rate ( ⁇ dot over ( ⁇ ) ⁇ ).
• Three or four extrusion pressures (6, 8, 12, 16 MPa) are typically selected for each polymer depending on its flow properties. For each extrusion pressure, a minimum of 3 MS measurements is performed and an average MS value is then obtained.
• the derivative function of the extrusion pressure dependent melt strength, ⁇ (MS)/ ⁇ (P) for each polymer is computed from the slope (by a least square line fitting) of the plot of the average MS against pressure.
• the mean melt strength at an extrusion pressure of 16 MPa, MS (16 MPa) can be computed from the plot.

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• 2001
  • 2001-11-20 EP EP01430035A patent/EP1312625A1/fr not_active Withdrawn
• 2002
  • 2002-11-14 WO PCT/GB2002/005160 patent/WO2003046025A1/fr not_active Application Discontinuation
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