WO1999035173A1

WO1999035173A1 - Catalyst for producing ethylene homopolymers and copolymers

Info

Publication number: WO1999035173A1
Application number: PCT/DE1998/003685
Authority: WO
Inventors: Diana ÖZDEMIR; Markus Schopf
Original assignee: Elenac Gmbh
Priority date: 1997-12-31
Filing date: 1998-12-11
Publication date: 1999-07-15
Also published as: DE19758306A1; DE19758306B4

Abstract

The invention relates to a heterogeneous catalyst for synthesising polyolefins, containing a metallocene compound, an aluminium or boron compound-based cocatalyst, a support material and a solvent. The proportion of solvent contained in the catalyst is between 1 and 20 wt. % in relation to its overall weight. Polyethylenes or copolymers of ethylene and 1-olefins can be produced advantageously using the inventive catalyst.

Description

Catalyst for the production of ethylene homopolymers and copolymers

The present invention relates to a heterogeneous (insoluble) catalyst which can advantageously be used in the ethylene polymerization and copolymerization of ethylene and 1-olefins.

EP-A-069 951 discloses processes for the production of polyolefms with the aid of homogeneous (soluble) catalyst systems. The known catalyst systems consist of a transition metal component of the metallocene type and a cocatalyst component, an oligomeric aluminum compound of the aluminoxane type, usually methylaluminoxane (MAO), which give narrowly distributed polymers or copolymers with high activity. A fundamental disadvantage of these homogeneous metallocene / aluminoxane catalyst systems in processes in which the polymer formed is a solid is the formation of heavy deposits on the reactor walls and stirrer. Such deposits in the reactor systems have to be removed at short intervals since they quickly reach considerable strengths and thereby prevent the heat exchange to the cooling medium. Further disadvantages of the homogeneous catalyst systems mentioned are that the morphology of the polymer particles formed in this way is technically not very advantageous because it leads to low bulk densities, to a broad particle size distribution and to an irregular particle shape. In addition, very large amounts of the costly cocatalyst, methylaluminoxane, have to be used because high catalyst activity can only be achieved with a high MAO / metallocene ratio.

To avoid the formation of deposits in the reactor, supported catalyst systems have been proposed in EP-A-206794, in which the metallocene and the aluminoxane serving as cocatalyst have been fixed on an inorganic support material, in particular an inorganic oxide. However, the prior art described there still has numerous disadvantages, which relate in particular to the catalyst performance and the catalyst production: In the case of longer polymerization times, it is shown that the formation of deposits is far less than in the comparable homogeneous catalyst system, but is nevertheless not completely suppressed, especially not if the polymerization is carried out in a suspending agent (slurry polymerization). The catalyst activity, based on the catalyst solid, is unsatisfactorily low, the polymer grain morphology does not meet the technical requirements.

The catalyst preparation procedure has the disadvantage that relatively large amounts of a solvent or suspending agent (generally toluene) are used; to obtain the ready-to-use catalyst, these must be removed by decanting and evacuating and either discarded or purified by distillation and / or adsorption before being reused. The latter process steps are costly in the technical production of catalysts and are therefore economically disadvantageous.

To avoid these process disadvantages, catalyst production processes have been proposed in which the amount of solvent used is reduced, so that the decanting step for separating off the solvent is eliminated.

A drying step which reduces the residual solvent content on the solid catalyst must follow the catalyst preparation. An excessive amount of solvent leads to easy washing out of catalyst constituents during the polymerization and thus to the formation of deposits, an insufficient amount can result in the formation of electrostatic product deposits in the reactor as well as a lower long-term stability of the solid catalyst during the polymerization.

The object of the present invention was to find a supported metallocene catalyst which can be stored for at least 10 weeks and which has very good activity in the ethylene homopolymerization or copolymerization in the suspension process and shows product morphology, but at the same time does not cause any annoying deposit formation.

This object is achieved according to the invention by a metallocene catalyst system which contains a metallocene compound, a cocatalyst based on an aluminum or boron compound, a support material and a solvent and whose characteristic feature is that, based on its total weight, it has a solvent content in Has a range from 1 to 20% by weight, preferably from 5 to 10% by weight.

In the production of such a catalyst system, it is particularly advantageous if the amount of solvent used is chosen such that no suspension of the insoluble support material in the solvent occurs during its production, but on the other hand there is a uniform wetting of the support material and thus a homogeneous distribution of the catalyst on the support is guaranteed. An essential parameter for this is the ratio between the amount of solvent used in the catalyst production and the free pore volume of the support material. The ratio of these sizes is particularly suitable if, when solution and carrier material are combined, a homogeneous, gelatinous mass which no longer flows is formed. The appropriate volume of solvent depends on the nature of the solvent and the

Carrier material and usually moves in the range of 1.0 to 3.0 times the pore volume of the carrier material.

The pore volume is a characteristic of spherical SiO ₂ carriers and is usually specified by the manufacturer. The exact determination of the pore volume is carried out by titration with water. A sample of carrier material is heated to a temperature of 200 ° C over a period of 2 hours. An amount of 10 to 40 g is then weighed into a closable container and an amount of water is then added which corresponds to approximately 80% of the pore volume to be expected. After shaking vigorously, the mixture is then cooled to room temperature, after which further portions of water are added until a saturated gel has formed and until the water just begins to wet the surface of the carrier material. Between the individual additions of water, shake vigorously again and again to evenly distribute the water. The value for the pore volume then results from the amount of water in [ml] divided by the original weight of the sample in [g].

The metallocene catalyst system according to the invention thus contains at least one metallocene compound, at least one cocatalyst, at least one support material and at least one solvent.

Suitable metallocene compounds are, for example, bridged or unbridged biscyclopentadienyl complexes, such as those e.g. in EP-A-129 368, EP-A-561 479, EP-A-545 304 and EP-A-576 970, monocyclopentadienyl complexes such as bridged amidocyclopentadienyl complexes which e.g. are described in EP-A-416 815, multinuclear cyclopentadienyl complexes as described in EP-A-632 063, π-ligand-substituted tetrahydropentalenes as described in EP-A-659 758 or π-ligand-substituted tetrahydroindenes as in EP-A A-661 300.

Preferred metallocene starting compounds are unbridged or bridged metallocene compounds of the formula I,

wherein M ^{1 is} a metal of III., IV., V. or VI. Subgroup of the Periodic Table of the Elements, in particular Ti, Zr or Hf, R ^{1 are} identical or different and are a hydrogen atom or SiR ₃ ³ , in which R ^3, identical or different, is a hydrogen atom or a C, -C ₄₀ -carbon-containing group such as C, -C ₂₀ alkyl, C, -C _{] 0} fluoroalkyl, C, -C _I0 alkoxy, C ₆ -C ₂₀ aryl, C ₆ -C ₁₀ -

Fluoroaryl, C ₆ -C _{] 0} aryloxy, C ₂ -C ₁₀ alkenyl, C ₇ -C ₄₀ arylalkyl, C ₇ -C ₄₀ alkylaryl or C ₈ -C ₄₀ arylalkenyl, or R ^{1 is} a C, -C ₃₀ - carbon-containing group such as C, -C ₂₅ - alkyl, for example methyl, ethyl, tert-butyl, cyclohexyl or octyl, C ₂ -C ₂₅ alkenyl, C ₃ -C _{] 5} - alkylalkenyl, C ₆ -C _24- aryl, C ₅ -C ₂₄ heteroaryl such as pyridyl, furyl or quinolyl, C ₇ - C ₃₀ arylalkyl, C ₇ -C ₃₀ alkylaryl, fluorine-containing C, -C ₂₅ alkyl, fluorine-containing C ₆ -C ₂₄ - Aryl, fluorine-containing C ₇ -C ₃₀ arylalkyl, fluorine-containing C ₇ -C ₃₀ alkylaryl or C _r C ₁₂ alkoxy, or two or more radicals R ¹ can be linked to one another in such a way that the radicals R ¹ and those connecting them Atoms of the cyclopentadienyl ring form a C ₄ -C ₂₄ ring system, which in turn can be substituted, R ^{2 are the} same or different and are a hydrogen atom or SiR ₃ ³ , where R ^{3 is} identical or different a hydrogen atom or a C, -C ₄₀ - carbon-containing group such as C, -C ₂₀ alkyl, C, -C _{] 0} fluoroalkyl, C _r C ₁₀ alkoxy, C ₆ -C, ₄ aryl, C ₆ -C ₁₀ fluoroaryl, C ₆ -C ₁₀ aryloxy, C ₂ -C ₁₀ alkenyl, C ₇ -C ₄₀ arylalkyl, C ₇ -C ₄₀ alkylaryl or C ₈ -C ₄₀ arylalkenyl, or R ^{2 is} a C _] -C ₃₀ carbon-containing group such as C, -C ₂₅ alkyl, for example methyl, ethyl, tert-butyl, cyclohexyl or octyl, C ₂ -C ₂₅ alkenyl, C ₃ -C ₁₅ -

Alkylalkenyl, C ₆ -C ₂₄ aryl, C ₅ -C ₂₄ heteroaryl, e.g. B. pyridyl, furyl or quinolyl, C ₇ -C ₃₀ arylalkyl, C ₇ -C ₃₀ alkylaryl, fluorine-containing C, -C ₂₅ alkyl, fluorine-containing C ₆ -C ₂₄ aryl, fluorine-containing C ₇ -C ₃₀ arylalkyl are fluorine-containing C ₇ -C ₃₀ alkylaryl or C, -C _I2 alkoxy, or two or more radicals R ² can be bonded to one another in such a way that the radicals R ² and the atoms of the cyclopentadienyl ring connecting them form a C ₄ -C ₂₄ -

Form a ring system, which in turn can be substituted, 1 is 1, 2, 3, 4 or 5 for v = 0 and 1 is 1, 2, 3 or 4 for v = 1, m is 1, 2, 3, 4 or 5 for v = 0 and m is 1, 2, 3 or 4 for v = 1, L ^{1 can be the} same or different and a hydrogen atom, a halogen atom, or OR ⁶ , SR ⁶ , OSiR ₃ ⁶ , SiR ₃ ⁶ , PR ₂ ⁶ or NR ₂ ⁶ , wherein R ^{6 is} a halogen atom, a C _] -C, ₀ alkyl group, a halogenated C, -C ₁₀ alkyl group, a C ₅ -C ₂₀ aryl group or a halogenated C ₆ -C ₂₀ aryl group, or L ¹ are a toluenesulfonyl, trifluoroacetyl, trifluoroacetoxyl, trifluoromethanesulfonyl -, Nonafluorobutanesulfonyl or 2,2,2-trifluoroethanesulfonyl group, o is an integer from 1 to 4, preferably 2,

Z denotes a bridging structural element between the two cyclopentadienyl rings and v is 0 or 1.

Examples of Z are groups M ² R ⁴ R ⁵ , where M ^{2 is} carbon, silicon, germanium or tin and R ⁴ and R ^5, identical or different, are a C, -C ₂₀ -hydrocarbon-containing group, such as C _r C ₁₀ alkyl, C ₆ -C ₁₄ aryl or trimethylsilyl. Z is preferably CH ₂ , CH ₂ CH ₂ , CH (CH ₃ ) CH ₂ , CH (C ₄ H ₉ ) C (CH ₃ ) ₂ , C (CH ₃ ) ₂ , (CH ₃ ) ₂ Si, (CH ₃ ) ₂ Ge, (CH ₃ ) ₂ Sn, (C ₆ H ₅ ) ₂ Si, (C ₆ H ₅ ) (CH ₃ ) Si, (C ₆ H ₅ ) ₂ Ge, (C ₆ H ₅ ) ₂ Sn , (CH ₂ ) ₄ Si, CH ₂ Si (CH ₃ ) ₂ , oC ₆ H ₄ or 2,2 ^' - (C ₅ H ₄ ) ₂ . Z can also form a mono- or polycyclic ring system with one or more radicals R ¹ and / or R ² .

Typical examples of metallocene starting compounds are:

Dimethylsilanediylbis (indenyl) zirconium dichloride

Dimethylsilanediylbis (4-naphthyl-indenyl) zirconium dichloride dimethylsilanediylbis (2-methyl-benzo-indenyl) zirconium dichloride dimethylsilanediylbis (2-methyl-indenyl) zirconium dichloride dimethylsilanediylbis (2-methyl-4-) methyl-4- (2-naphthyl) -indenyl) zirconium dichloride dimethylsilanediylbis (2-methyl-4-phenyl-indenyl) zirconium dichloride dimethylsilanediylbis (2-methyl-4-t-butyl-indenyl) zirconium dichloride dimethylsilanediylbis (2-methyl -indenyl) zirconium dichloride dimethylsilanediylbis (2-methyl-4-ethyl-indenyl) zirconium dichloride dimethylsilanediylbis (2-methyl-4-α-acenaphth-indenyl) zirconium dichloride dimethylsilanediylbis (2,4-dimethyl-indenylethyldilidyldilidyldilyldilyldilyldilyldilidyldilidyl) (zirconium) ) zirconium dichloride Dimethylsilanediylbis (2-ethyl-4-ethyl-indenyl) zirconium dichloride Dimethylsilanediylbis (2-ethyl-4-phenyl-indenyl) zirconium dichloride Dimethylsilandiybis (2-methyl-4,5-benzo-indenyl) zirconium dichloride Dimethylsilanediylbis ( diisopropyl-indenyl) zirconium dichloride dimethylsilanediylbis (2-methyl-4,5-diisopropyl-indenyl) zirconium-dichloride dimethylsilanediylbis (2,4,6-trimethyl-indenyl) zirconium-dichloride dimethylsilanediylbis (2,5,6-trimethyl-indenyldichlorodi-bis-2,5) , 7-trimethyl-indenyl) zirconium dichloride dimethylsilanediylbis (2-methyl-5-isobutyl-indenyl) zirconium dichloride dimethylsilanediylbis (2-methyl-5-t-butyl-indenyl) zirconium dichloride

Methyl (phenyl) silanediylbis (2-methyl-4-phenyl-indenyl) zirconium dichloride Methyl (phenyl) silanediylbis (2-methyl-4,6-diisopropyl-indenyl) zirconium dichloride Methyl (phenyl) silanediylbis (2-methyl-4-isopropyl-indenyl ) zirconium dichloride methyl (phenyl) silanediylbis (2-methyl-4,5-benzo-indenyl) zirconium dichloride methyl (phenyl) silanediylbis (2-methyl-4,5- (methylbenzo) -indenyl) zirconiumdichloride methyl (phenyl) silanediylbis ( 2-methyl-4,5- (tetramethylbenzo) -indenyl) zirconium dichloride methyl (phenyl) silanediylbis (2-methyl-4-α-acenaphth-indenyl) zirconium dichloride methyl (phenyl) silanediylbis (2-methyl-indenyl) zirconium dichloride methyl (phenyl ) silanediylbis (2-methyl-5-isobutyl-indenyl) zirconium dichloride l, 2-ethanediylbis (2-methyl-4-phenyl-indenyl) zirconium dichloride l, 4-butanediylbis (2-methyl-4-phenyl-indenyl) zirconium dichloride l, 2-ethanediylbis (2-methyl-4,6-diisopropyl-indenyl) zirconium dichloride l, 4-butanediylbis (2-methyl-4-isopropyl-indenyl) zirconium dichloride l, 4-butanediylbis (2-methyl-4,5-benzo-indenyl) ) zirconium dichlor id l, 2-ethanediylbis (2-methyl-4,5-benzo-indenyl) zirconium dichloride l, 2-ethanediylbis (2,4,7-trimethyl-indenyl) zirconium dichloride l, 2-ethanediylbis (2-methyl-indenyl) zirconium dichloride 1,4-butanediylbis (2-methyl-indenyl) zirconium dichloride [4- (η ⁵ -cyclopentadienyl) -4,6,6-trimethyl- (η ⁵ -4,5-tetrahydropentalen)] - dichlorozirconium [4- (η ⁵ -3'-trimethylsilyl-cyclopentadienyl) -4,6,6-trimethyl- ^(η: -4,5-tetrahydropentalene)] - dichlorozirconium

[4- (η ⁵ -3'-isopropyl-cyclopentadienyl) -4,6,6-trimethyl- (η ⁵ -4,5-tetrahydropentalene)] - dichlorozirconium [4- (η ⁵ -cyclopentadienyl) -4.7, 7-trimethyl- (η ⁵ -4,5,6,7-tetrahydroindenyl)] dichlorotitanium

[4- (η ⁵ -cyclopentadienyl) -4,7,7-trimethyl- (η ⁵ -4,5,6,7-tetrahydroindenyl)] dichlorozirconium

[4- (η ⁵ -cyclopentadienyl) -4,7,7-trimethyl- (η ⁵ -4,5,6,7-tetrahydroindenyl)] - dichlorohafhium

[4- (η ⁵ -3'-tert-butyl-cyclopentadienyl) -4,7,7-trimethyl- (η ⁵ -4,5,6,7-tetrahydroindenyl)] - dichlorotitanium 4- (η ⁵ -3 ' -Isopropylcyclopentadienyl) -4,7,7-trimethyl- (η ⁵ -4,5,6,7-tetrahydroindenyl)] - dichlorotitanium

4- (η ⁵ -3'-methylcyclopentadienyl) -4,7,7-trimethyl- (η ⁵ -4,5,6,7-tetrahydroindenyl)] - dichlorotitanium

4- (η ⁵ -3'-trimethylsilyl-cyclopentadienyl) -2-trimethylsilyl-4,7,7-trimethyl- (η ⁵ -4,5,6,7-tetrahydroindeny 1)] dichlorotitanium

4- (η ⁵ -3'-tert-butyl-cyclopentadienyl) -4,7,7-trimethyl- (η ⁵ -4,5,6,7-tetrahydroindenyl)] - dichlorozirconium

(Tertbutylamido) - (tetramethyl-η ⁵ -cyclopentadienyl) -dimethylsilyl-dichlorotitanium

(Tertbutylamido) - (tetramethyl-η ⁵ -cyclopentadienyl) -l, 2-ethanediyl-dichlorotitan-dichlorotitan (Methylamido) - (tetramethyl-η ⁵ -cyclopentadienyl) -dimethylsilyl-dichlorotitan

(Methylamido) - (tetramethyl-η ⁵ -cyclopentadienyl) -l, 2-ethanediyl-dichlorotitan

(Tertbutylamido) - (2,4-dimethyl-2,4-pentadien-l-yl) dimethylsilyl dichlorotitanium

Bis (cyclopentadienyl) zirconium dichloride

Bis- (n-butylcyclopentadienyl) zirconium dichloride Bis- (1,3-dimethylcyclopentadienyl) zirconium dichloride

Tetrachloro- [1 - [bis (η ⁵ - 1 H-inden- 1-ylidene) methylsilyl] -3 -η ⁵ -cyclopenta-2, 4-diene-1-ylidene) -3 - η ⁵ -9H-fluorene- 9-ylidene) butane] di-zirconium

Tetrachloro- [2- [bis (η ⁵ -2-methyl-lH-inden-l-ylidene) methoxysilyl] -5- (η ⁵ -2,3,4,5-tetramethylcyclopenta-2,4-diene-l- ylidene) -5- (η ⁵ -9H-fluoren-9-ylidene) hexane] di-zirconium Tetrachloro- [l- [bis (η ⁵ -lH-inden-l-ylidene) methylsilyl] -6- (η ^: '-cyclopenta-2,4-diene-l-ylidene) -6- (η ^Λ -9H- fluorene-9-ylidene) -3-oxaheptane] di-zirconium.

In principle, any compound which can convert the neutral metallocene into a cation and stabilize it is suitable as a cocatalyst in the process according to the invention. In addition, the cocatalyst or the anion formed from it should not undergo further reactions with the metallocenium cation formed (see EP-A-427 697). An aluminum compound and / or a boron compound is preferably used as the cocatalyst.

The boron compound preferably has the formula R ¹⁸ _X NH ₄ _ _X BR ¹⁹ ₄ , R ¹⁸ _X PH ₄ . _X BR ^{, 9} ₄ , R ¹⁸ ₃ CBR ¹⁹ ₄ or BR ^{, 9} ₃ , where x is a number from 1 to 4, preferably 3, the radicals R ^{18 are} identical or different, preferably identical, and C, -C ₁₀ Are alkyl or C ₆ -C ₁₈ aryl, or two radicals R ¹⁸ together with the atoms connecting them form a ring, and the radicals R ^{19 are} identical or different, preferably identical, and are C ₆ -C ₁₈ aryl, which can be substituted by alkyl, haloalkyl or fluorine. In particular, R ^{18 represents} ethyl, propyl, butyl or phenyl and R ^{19 represents} phenyl, pentafluorophenyl, 3,5-bistrifluoromethylphenyl, mesityl, xylyl or tolyl (EP-A-277 003, EP-A-277 004 and EP-A- 426 638).

An aluminum compound such as aluminoxane and / or an aluminum alkyl is preferably used as the cocatalyst.

An aluminoxane, in particular of the formula Ha for the linear type and / or of the formula Ilb for the cyclic type, is particularly preferably used as the cocatalyst, the radicals R ²⁰ in the formulas Ha and Ilb being the same or different and hydrogen or one

C, -C ₂₀ hydrocarbon group such as a C, -C ₁₈ alkyl group, a C ₆ -C ₁₈ aryl group or benzyl, and p is an integer from 2 to 50, preferably 10 to 35. The R ²⁰ radicals are preferably the same and are hydrogen, methyl, isobutyl, phenyl or benzyl, particularly preferably methyl.

If the R ²⁰ radicals are different, they are preferably methyl and hydrogen or alternatively methyl and isobutyl, hydrogen or isobutyl preferably being present in a numerical proportion of 0.01 to 40% (of the R ²⁰ radicals).

Processes for the preparation of the aluminoxanes are known. The exact spatial structure of the aluminoxanes is not known (J. Am. Chem. Soc. (1993) 115, 4971). For example, it is conceivable that chains and rings combine to form larger two-dimensional or three-dimensional structures.

Regardless of the type of production, all aluminoxane solutions have in common a changing content of unreacted aluminum starting compound, which is present in free form or as an adduct. It is possible to preactivate the metallocene compound with a cocatalyst, in particular an aluminoxane, before use in the polymerization reaction. This significantly increases the polymerization activity and ensures a firm and irreversible fixation of the catalyst components on the support material. The metallocene compound is preferably preactivated in solution. The metallocene compound is preferably dissolved in a solution of the aluminoxane in an inert solvent. Suitable solvents are aromatic hydrocarbons such as benzene or toluene or polar halogenated hydrocarbons such as chlorobenzene, methyl chloride, methylene chloride or chloroform. Toluene is preferably used.

The concentration of the aluminoxane in the solution is in the range from about 1% by weight to the saturation limit, preferably from 5 to 30% by weight, based in each case on the total amount of solution. The metallocene is used in an amount of 10 ³ to 1 mol per mol of aluminoxane, preferably 5-10 ³ to 2 10 ² mol per mol of aluminoxane. The preactivation time is 5 minutes to 60 hours, preferably 5 minutes to 12 hours. One works at a temperature of -78 to 100 ° C, preferably 0 to 80 ° C.

The carrier component of the catalyst system according to the invention can be any organic or inorganic, inert solid, in particular a porous carrier such as talc, silica, other inorganic oxides or finely divided polymer powders such as polyolefms.

Inorganic oxides of elements from groups 2, 3, 4, 5, 13, 14, 15 and 16 of the periodic table of the elements are suitable. Examples of preferred oxides as carriers include silicon dioxide, aluminum oxide, and mixed oxides of the two elements and corresponding oxide mixtures. Other inorganic oxides that can be used alone or in combination with the last-mentioned preferred carriers are MgO, ZrO ₂ or B ₂ O ₃ , to name just a few.

The carrier materials used have a specific surface area in the range from 10 m ² / g to 1000 m ² / g, a pore volume in the range from 0.1 ml / g to 5 ml / g and an average Particle size from 1 μm to 500 μm. Carriers with a specific surface area in the range from 50 m ² / g to 500 π / g, a pore volume in the range between 0.5 ml / g and 3.5 ml / g and an average particle size in the range from 5 μm to 350 are preferred μm. Carriers with a specific surface area in the range from 200 nm / g to 400 m ² / g, a pore volume in the range between 0.8 ml / g to 3.0 ml / g and an average particle size of 10 μm to 200 μm are particularly preferred .

Before the preactivation solution containing the metallocene compound, cocatalyst and solvent and the carrier material are combined, dilution of the preactivation solution with a suitable inert solvent ensures that the ratio of the volume of the preactivation solution to the pore volume of the carrier material is in a suitable range . The ratio of the volume of the preactivation solution to the pore volume is suitable if a non-flowable, homogeneous, gelatinous mass is formed when combined. The appropriate volume of the preactivation solution depends on the nature of the solvent and the

Carrier material and normally ranges from 1.0 to 3.0 times the pore volume of the carrier material.

Solvents suitable according to the invention are aromatic hydrocarbons such as benzene or toluene or polar halogenated hydrocarbons such as chlorobenzene, methyl chloride, methylene chloride or chloroform. Toluene is preferably used.

The supported catalyst system can either be used directly for the polymerization of olefins or prepolymerized with one or more olefinic monomers before it is used in a polymerization process. This is what is supported

Suspended catalyst system in an inert hydrocarbon such as hexane and prepolymerized at a temperature of 0 ° C to 60 ° C in the presence of at least one olefin such as ethylene, propylene, hexene, butene or 4-methyl-1-pentene. The prepolymerized catalyst system can then be dried until it is free-flowing. Alternatively, the suspension can also be used directly for the polymerization be used. Another possible embodiment variant is to prepolymerize the catalyst system in the gas phase. For this purpose, at least one olefin of the above meaning is passed through the catalyst system in powder form with stirring.

As an additive, a small amount of a 1-olefin, such as styrene, can be added as an activity-increasing component or an antistatic during or after the preparation of the supported catalyst system.

The present invention also relates to a process for the preparation of a polyolefin by polymerizing one or more olefins in the presence of the catalyst system according to the invention comprising at least one metallocene of the formula I. The term polymerization is understood to mean homopolymerization and also copolymerization.

The supported catalyst system can be used as a scavenger for the polymerization of olefins in combination with an aluminum alkyl or an aluminoxane. The soluble aluminum components are added to the monomer or the suspending agent and are used to purify the polymerization batch from substances which can impair the catalyst activity. The amount of aluminum component added depends on the quality of the monomers and suspending agents used. Aluminum alkyls such as trimethyl aluminum (TMA), triethyl aluminum (TEA) or triisobutyl aluminum (TIBA) are preferably used as scavengers.

Olefins of the formula R ^a -CH = CH-R ^b are preferably polymerized, in which R and R ^{b are} identical or different and denote a hydrogen atom or a carbon-containing radical having 1 to 20 C atoms, in particular 1 to 10 C atoms, and R ^a and R ^b together with the atoms connecting them can form one or more rings. Examples of such olefins are 1-olefins having 2 to 40, preferably 2 to 10, carbon atoms, such as ethene, propene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene or 1-octene, Styrene, dienes such as 1,3-butadiene, 1,4-hexadiene, vinyl norbornene, norbornadiene, ethyl norbornadiene and cyclic olefins such as norbornene, tetracyclododecene or methyl norbornene. Ethene is preferably homopolymerized in the process according to the invention, or ethene with one or more 1-olefins having 4 to 20 C atoms, such as butene or hexene, and / or one or more dienes having 4 to 20 C atoms, such as 1, 4 -Butadien, Norbornadien,

Ethylidene norbornene or ethyl norbornadiene, copolymerized. 1-Butene and 1-hexene are preferably used as comonomers.

The polymerization is carried out at a temperature of -60 ° C to 300 ° C, preferably 50 ° C to 200 ° C, most preferably 65 ° C to 90 ° C. The pressure is 0.5 bar to 2000 bar, preferably 5 bar to 64 bar, very particularly preferably 5 bar to 10 bar.

The catalyst system according to the invention can be used both in a suspension polymerization and in a gas phase polymerization. A suspension process is preferably used.

The polymerization proceeds with high activity without formation of deposits and results in a polymer with a uniform grain morphology.

The following exemplary embodiments are intended to illustrate the invention even more clearly for a person skilled in the art.

Examples 1-3 describe for three different metallocene compounds the preparation of supported catalysts with the amount of solvent according to the invention during catalyst preparation (characterized by the ratio of the volume of the

Preactivation solution for the pore volume of the support material) and residual solvent content according to the invention of the finished catalyst.

Comparative example 3A describes a catalyst which has too little residual solvent content. Comparative example 3B describes a catalyst which has an excessively high residual solvent content.

Comparative Example 3C describes a catalyst in which the amount of solvent used was too small.

Comparative example 3D describes a catalyst in the production of which an excessive amount of solvent was used.

With all of the catalysts produced in this way, two test polymerizations (polymerizations 1 and 2) are carried out within 1-3 days after the preparation. Another test polymerization (Polymerization 3) is carried out after 60-90 days after the preparation.

Tables 1 and 2 summarize the characteristic features of the catalysts (solvent / pore volume ratio in catalyst synthesis and residual toluene content of the finished catalyst) and the results of the test polymerizations. As a measure of the activity of the catalyst, the size "KZAred" is used, which indicates how much polyethylene per mmol of Zr and bar of ethylene pressure per hour with the respective

Catalyst is obtained. The bulk density of the polymer powder (SD) is used to assess the product morphology, for technical reasons the highest possible SD value is aimed for.

example 1

820 mg of the metallocene Cp ₂ ZrCl _{2 are dissolved} in a Schlenk vessel with stirring in 57 ml of a 30% methylaluminoxane solution in toluene (MAO solution, manufacturer: Albemarle). After an hour of reaction, 100 ml of toluene are added. This mixture is stirred for a further 30 min, then 41 g of the

Carrier material XPO 2402 based on silica from Grace. The used The carrier material has a pore volume of 1.50 ml / g. The solution has 2.5 times the pore volume of the silica. A no longer flowable, homogeneous, gelatinous mass is created. The stirring is stopped and the catalyst is dried under high vacuum at room temperature. After 4 hours, the drying is ended at a toluene content of the catalyst of 9%.

A 1.5 l steel autoclave is filled with 750 ml Exxsol D 100/120, 0.5 ml 20% TIBA solution (TIBA = triisobutylaluminum) and a defined amount of the catalyst and heated to 70 ° C. Then polymerized with an ethylene partial pressure of 4 bar for one hour. Two test polymerizations are carried out shortly after the catalyst has been prepared (2.55 g or 2.68 g of catalyst) and a further approximately 2 months after the catalyst has been prepared (2.61 g of catalyst).

No deposits were found in the reactor during the polymerizations. The sieve analysis shows no fines, the microscopic examination shows the very uniform, spherical morphology of the products. The results of the test polymerizations are shown in Table 1. All three polymerizations give very similar results and thus demonstrate the homogeneous composition of the catalyst and its good long-term stability.

Example 2

The catalyst is prepared analogously to Example 1 from 790 mg Me ₂ Si (2-Me-4-Ph-Ind) ₂ ZrCl ₂ , 38 ml MAO solution, 42 g of the carrier XPO 2402 and 93 ml toluene. The solution has 2.1 times the pore volume of the carrier material. A residual toluene content of 10% is set by drying.

In the polymerizations analogous to example 1 with the catalyst according to example 2 (3.25 g or 3.10 g or 3.26 g catalyst), no formation of deposits was found in the reactor. The sieve analysis shows no fines, the microscopic examination shows the very uniform, spherical morphology of the products. The results of the test polymerizations are shown in Table 1. All three polymerizations give very similar results and thus demonstrate the homogeneous composition of the catalyst and its good long-term stability.

Example 3

The catalyst is prepared analogously to Example 1 from 780 mg (n-Bu-Cp) ₂ ZrCl ₂ , 59 ml of MAO solution, 42 g of the carrier XPO 2402 and 110 ml of toluene. The solution has 2.7 times the pore volume of the carrier material. A residual toluene content of 8% is set by drying.

In the polymerizations analogous to Example 1 with the catalyst according to Example 3 (0.78 g or 0.61 g or 0.71 g catalyst), no formation of deposits in the reactor was found. The sieve analysis shows no fines, the microscopic examination shows the very uniform, spherical morphology of the products. The results of the test polymerizations are shown in Table 1. All three polymerizations give very similar results and thus demonstrate the homogeneous composition of the catalyst and its good long-term stability.

Example 3A

The catalyst is prepared analogously to Example 1 from 780 mg (n-Bu-Cp) ₂ ZrCl ₂ , 59 ml of MAO solution, 42 g of the carrier XPO 2402 and 110 ml of toluene. The solution has 2.7 times the pore volume of the carrier material. The catalyst is dried to constant weight, corresponding to a residual toluene content of 0%.

In the case of the polymerizations analogous to Example 1 with the catalyst according to Example 3A (0.58 g or 0.70 g or 0.70 g catalyst), product deposits adhering to the reactor due to electrostatic charging were found in all cases. The results of the test polymerizations are shown in Table 2. The shortly after manufacture Polymerizations carried out provide comparable results and thus demonstrate the homogeneity of the catalyst. The third polymerization carried out after about 2 months shows a clearly reduced activity. This shows that the long-term stability of the residual solvent-free catalyst is unsatisfactory.

Example 3B

The catalyst is prepared analogously to Example 1 from 780 mg (n-Bu-Cp) ₂ ZrCl ₂ , 59 ml of MAO solution, 42 g of the carrier XPO 2402 and 110 ml of toluene. The solution has 2.7 times the pore volume of the carrier material. A residual toluene content of 28% is set by drying.

In the polymerizations analogous to Example 1 with the catalyst according to Example 3B (1.09 g or 1.21 g or 1.08 g catalyst), deposits were found in the reactor. The products had low bulk densities. The microscopic examination of the products showed not only uniformly spherical polymer grains but also irregularly shaped components. The formation of these product fractions can be traced back to homogeneous catalysis, which results from the partial washing out of catalyst components from the support. The clear differences in activity in the polymerization experiments suggest that different catalytic centers

(heterogeneous and homogeneous) side by side. The results of the test polymerizations are shown in Table 2.

Example 3C

The catalyst is prepared analogously to Example 1 from 740 mg (n-Bu-Cp) ₂ ZrCl ₂ , 56 ml of MAO solution, 40 g of the carrier XPO 2402 and 30 ml of toluene. The solution has 1.4 times the pore volume of the carrier material. A residual toluene content of 7% is set by drying. In the polymerizations analogous to Example 1 with the catalyst according to Example 3C (0.71 g or 0.80 g or 0.72 g catalyst), no formation of deposits was found in the reactor. The microscopic examination of the products shows a non-uniform spherical morphology, it can be seen that not all silica particles are fragmented in the course of the polymerization. This is due to the fact that not all parts of the support material were soaked uniformly with the catalyst solution during the preparation. This non-uniformity of the catalyst is also evident in the clear differences in activity of the test polymerizations. The exact results of the test polymerizations are shown in Table 2.

Example 3D

The catalyst is prepared analogously to Example 1 from 810 mg (n-Bu-Cp) ₂ ZrCl ₂ , 61 ml of MAO solution, 44 g of the XPO 2402 support and 200 ml of toluene. The solution has 4 times the pore volume of the carrier material. When the carrier material is stirred into the solution, a suspension is formed in which a separation between the liquid and solid phases can be observed. A residual toluene content of 5% is set by drying.

In the polymerizations analogous to Example 1 with the catalyst according to Example 3D (0.67 g or 0.74 g or 0.65 g catalyst), the formation of deposits in the reactor is determined. The products have low bulk densities. The microscopic examination of the products shows mainly non-uniformly large spherical particles as well as irregularly shaped components, which apparently resulted from homogeneous catalysis. This suggests a partial washing out of catalyst components from the support. The clear differences in activity in the polymerization experiments indicate that different catalytic centers (heterogeneous and homogeneous) exist side by side. The exact results of the test polymerizations are shown in Table 2.

Table 1: Polymerization experiments with catalysts according to the invention

Table 2: Polymerization experiments with catalysts not according to the invention

Claims

claims

1. Metallocene catalyst system comprising a metallocene compound, a cocatalyst based on an aluminum or boron compound, a support material and a solvent, characterized in that the catalyst system has a solvent content in the range from 1 to 20% by weight, based on its total weight.

2. Metallocene catalyst system according to claim 1, characterized in that the metallocene compound is an unbridged or bridged metallocene compound

Formula I is

woπn

M ^{1 is} a metal of III., TV., V. or VI. Subgroup of the periodic table of the elements, in particular Ti, Zr or Hf,

R 'are identical or different and are a hydrogen atom or SiR ₃ ³ , in which R ^3, identical or different, is a hydrogen atom or a C, -C ₄₀ -carbon-containing group such as C, -C ₂₀ alkyl, C, -C ₁₀ fluoroalkyl, C, -C ₁₀ alkoxy, C ₆ -C ₂₀ aryl, C ₆ -C ₁₀ fluoroaryl, C ₆ -C ₁₀ aryloxy, C, -C ₁₀ alkenyl, C ₇ -C ₄₀ arylalkyl, C ₇ -C ₄₀ alkylaryl or C ₈ -C ₄₀ arylalkenyl, or R ^{1 is} a C, -C ₃₀ - carbon-containing group such as C, -C ₂₅ -

Alkyl, for example methyl, ethyl, tert-butyl, cyclohexyl or octyl, C, -C ₂₅ alkenyl, C ₃ -C ₁₅ - Alkylalkenyl, C ₆ -C ₂₄ aryl, C ₅ -C ₂₄ heteroaryl such as pyridyl, furyl or quinolyl, C ₇ - C ₃₀ arylalkyl, C ₇ -C ₃₀ alkylaryl, fluorine-containing C, -C ₂₅ - alkyl, fluorine-containing C ₆ -C ₂₄ aryl, fluorine-containing C ₇ -C ₃₀ arylalkyl, fluorine-containing C ₇ -C ₃₀ alkylaryl or C, -C ₁₂ alkoxy, or two or more radicals R 'can be linked to one another such that the R ¹ radicals and the atoms connecting them of the cyclopentadienyl ring are a C -C ₂₄ -

Form a ring system, which in turn can be substituted, R ^{2 are the} same or different and are a hydrogen atom or SiR ₃ ³ , wherein R ^{3 is the} same or different a hydrogen atom or a C, -C ₄₀ carbon-containing group such as C, -C ₂₀ alkyl , C, -C ₁₀ fluoroalkyl, C, -C ₁₀ alkoxy, C ₆ -C ₁₄ aryl, C ₆ -C ₁₀ fluoroaryl, C ₆ -C ₁₀ aryloxy, C ₂ -C _I0 alkenyl, C ₇ -C ₄₀ arylalkyl, C ₇ -C ₄₀ alkylaryl or

C ₈ -C ₄₀ arylalkenyl, or R ^{2 is} a C, -C ₃₀ carbon-containing group such as C, -C ₂₅ alkyl, for example methyl, ethyl, tert-butyl, cyclohexyl or octyl, C ₂ -C ₂₅ - Alkenyl, C ₃ -C ₁₅ alkylalkenyl, C ₆ -C ₂₄ aryl, C ₅ -C ₂₄ heteroaryl, e.g. B. pyridyl, furyl or quinolyl, C ₇ -C ₃₀ arylalkyl, C ₇ -C ₃₀ alkylaryl, fluorine-containing C, -C ₂₅ alkyl, fluorine-containing C ₆ -C ₂₄ aryl, fluorine-containing C ₇ -C ₃₀ arylalkyl are fluorine-containing C ₇ -C ₃₀ alkylaryl or C, -C ₁₂ alkoxy, or two or more radicals R ² can be bonded to one another in such a way that the radicals R ² and the atoms of the cyclopentadienyl ring connecting them form a C ₄ -C ₂₄ Form a ring system, which in turn can be substituted, 1 is 1, 2, 3, 4 or 5 for v = 0, and 1 is 1, 2, 3 or 4 for v = 1, m is 1, 2,

3,

4 or 5 for v = 0, and m is 1, 2, 3 or 4 for v = 1,

L ^{1 can be the} same or different and represent a hydrogen atom, a halogen atom, or OR ⁶ , SR ⁶ , OSiR ₃ ⁶ , SiR ₃ ⁶ , PR ₂ ⁶ or NR ₂ ⁶ , wherein R ^{6 is} a halogen atom, a C, -C ₁₀ Are alkyl group, a halogenated C, -C ₁₀ alkyl group, a C ₆ -C ₂₀ aryl group or a halogenated C ₆ -C ₂₀ aryl group, or L ¹ are a toluenesulfonyl, trifluoroacetyl, trifluoroacetoxyl, trifluoromethanesulfonyl, nonafluorobutanesulfonyl or 2 , 2,2-trifluoroethanesulfonyl group, o is an integer from 1 to 4, preferably 2,

Z denotes a bridging structural element between the two cyclopentadienyl rings and v is 0 or 1. Metallocene catalyst system according to Claim 1 or 2, characterized in that an aluminum compound such as aluminoxane and / or an aluminum alkyl is used as cocatalyst, preferably an aluminoxane, in particular of the formula Ila for the linear type and / or of the formula IIb for the cyclic type, wherein in the formulas Ila and Ilb the radicals R ^{20 are} identical or different and are hydrogen or a C, -C ₂₀ hydrocarbon group such as a C, -C ₁₈ alkyl group, a C ₆ -C _1S aryl group or benzyl, and p is an integer from 2 to 50, preferably 10 to 35.

Metallocene catalyst system according to one of claims 1 to 3, characterized in that the solvent is an aromatic hydrocarbon such as benzene or toluene and that the solvent content is in the range of 5 to 10 wt .-%.

5. Use of a metallocene catalyst system according to claim 1 for the polyolefin synthesis in a suspension polymerization.

6. Use of a metallocene catalyst system according to claim 1 for polyolefin synthesis in a gas phase polymerization.

7. Use of a metallocene catalyst system according to claim 1 for the synthesis of polyethylene.

8. A method for producing a metallocene catalyst system according to claim 1, in which the metallocene and the cocatalyst are first reacted in solvent and in which the reaction product is then combined with the support material, characterized in that the amount of solvent is adjusted so that when the solution and the carrier material are combined, a gelatinous, homogeneous mass which is no longer flowable is formed, which is then dried until a solvent content in the

Setting range from 1 to 20 wt .-%.