Efficient process for recovery and conversion of methylaluminoxane residues

Abstract

The present invention relates to an efficient process for the preparation of highly active polymerization co-catalysts by reacting methylaluminoxane residues with C6-C18-alkyl aluminum compounds in the presence of a hydrocarbon solvent.

Description

Technical Field

[0001] This invention relates to a method for reacting methylaluminoxane residues with C6-C 18 An effective method for preparing highly active polymerization cocatalysts by reacting alkylaluminum compounds in the presence of hydrocarbon solvents. Background Technology

[0002] Over the past few decades, alkylaluminoxanes, particularly methylaluminoxanes, have attracted considerable interest as initiators for the production of polyolefins, among other applications. They are typically prepared via the controlled hydrolysis of trimethylaluminum in toluene or other hydrocarbon solvents.

[0003] US 3,219,591 discloses the catalytic activity of a compound formed by the reaction of trialkylaluminum with a limited amount of water in the polymerization of ethylene oxide.

[0004] Manyik et al. reported in US 3,242,099 the use of aluminoxanes prepared by reacting 0.85–1.05 moles of water with alkylaluminum compounds (such as triisobutylaluminum) as co-catalysts in the polymerization of monounsaturated α-olefins, together with certain transition metal compounds.

[0005] The same author describes the preparation of alkylaluminoxanes in US 3,300,458, which is carried out by passing a hydrocarbon through water to form a wet hydrocarbon and mixing the wet hydrocarbon with an alkylaluminum solution in a conduit.

[0006] US 4,730,071 and 4,722,736 illustrate other methods for preparing methylaluminoxane by dispersing water in toluene using an ultrasonic bath or a high-shear impeller to produce a dispersion and then adding a toluene solution of trimethylaluminum to the dispersion.

[0007] The main problem arising from adding water to alkylaluminum compounds (particularly trimethylaluminum) to produce solutions of methylaluminoxane in organic solvents is the presence of varying amounts of gels and / or small particles in the solution, which aggregate upon standing to form precipitates or additional gels. Even when particles and / or gels are removed by filtration, additional gels may form in the solution after 2 or 3 weeks, especially when the initially prepared dilute solution is concentrated to contain a higher methylaluminoxane content (which is more economically desirable for storage, transportation, and use).

[0008] Several attempts have been made to remove gels and / or small particles or other poorly soluble components from methylaluminoxane solutions.

[0009] WO 9319073 A1 discloses the addition of aliphatic hydrocarbons to a methylaluminoxane solution of aromatic hydrocarbons to specifically precipitate gels and dispersed solids.

[0010] EP 524,613A describes a method for obtaining a clear, gel-free solution of alkylaluminoxanes (such as methylaluminoxanes) in an organic solvent, wherein the solution of the alkylaluminoxane is treated with anhydrous alkali metal or alkaline earth metal hydroxide, and the resulting solid is then removed from the solution by filtration.

[0011] However, these methods do not make further use of the removed gel or precipitate, which means they must be carefully removed, for example, by complete hydrolysis, thus losing valuable raw materials.

[0012] Modified methylaluminoxanes having two or more different types of alkyl groups have also been proposed as cocatalysts and have shown at least equivalent effectiveness and activity in specific applications. Examples of such systems are described in WO2014 / 069989 A1; Macromolecules, 32, 9078 (1999); Journal of American Chemical Society, 118, 11664 (1996); and Organometallics, 18, 65 (1999).

[0013] Currently, these modified methylaluminoxanes are produced by combining trimethylaluminum with at least one other C2-C... 18 The hydrolysis of a mixture of alkyl aluminum compounds or by trimethylaluminum and at least one other C2-C 18 Alkyl aluminum compounds are prepared by reacting them with other suitable oxygen-containing molecules, such as carbon dioxide. Although such modified methylaluminoxanes exhibit better solubility (especially in aliphatic hydrocarbons), the aforementioned problems of solid formation and slight gelation remain essentially unchanged.

[0014] Since each of the above-mentioned methods in the prior art results in a complex reaction mixture with varying levels of gels and other precipitates, and thus leads to a reduced yield for aluminum compounds, there is an urgent need for an efficient and easy way to utilize such production residues. Summary of the Invention

[0015] A method for preparing modified methylaluminoxanes is now provided, the method comprising at least making a methylaluminoxane having the following...

[0016] i) An aluminum content of 30 to 50 wt.-%, preferably 35 to 50 wt.-%, and more preferably 40 to 50 wt.-%, relative to dry weight.

[0017] ii) Preferably, the molar ratio of methyl to aluminum is 0.6 to 1.4, more preferably 0.7 to 1.3, and even more preferably 0.90 to 1.30, and even more preferably 1.00 to 1.30, as determined by 1H-NMR.

[0018] These types of methylaluminoxanes are referred to below as "methylaluminoxane residues".

[0019] The step of contacting at least one compound of formula (I) in the presence of a hydrocarbon solvent

[0020] AIR3(I)

[0021] Where R represents C6-C 18 Alkyl, more preferably C8-C 16 Alkyl, and even more preferably C8-C 12 alkyl.

[0022] These and other features and advantages of the invention will become apparent from the following detailed description and claims. Detailed Implementation

[0023] The scope of the invention also covers any desired combination of preferred ranges and regions specified for each feature below.

[0024] Methylaluminoxane residues are used as the starting material for the method of the present invention.

[0025] Methylaluminoxanes (often also known as MAO) are typically produced via the controlled partial hydrolysis of trimethylaluminum, in which water and trimethylaluminum are reacted in a solvent (e.g., an aromatic hydrocarbon). The result is a complex mixture in solution containing numerous linear or cyclic polymeric structures, at least some of which exist in dynamic equilibrium.

[0026] Due to this dynamic behavior in all known production technologies, fractions of gel and dispersed solids are formed, which are practically insoluble in the organic solvents used for the production of methylaluminoxanes, and therefore separate from the methylaluminoxane solution upon standing or even more quickly upon centrifugation. Such fractions typically exhibit the composition and parameters described above for methylaluminoxane residues. These methylaluminoxane residues may contain varying amounts of hydrocarbon solvents.

[0027] Common methods for determining such gels include determining the aluminum content by inductively coupled plasma (ICP) analysis or titration after appropriate digestion of the sample, and calculating the ratio of methyl groups to aluminum by measuring the volume of gas released from the sample during hydrolysis (normalized to standard conditions), as further outlined in the experimental section.

[0028] The values ​​given above in the invention description represent methylaluminoxane residues containing gel and dispersed solids.

[0029] The methylaluminoxane residue used in the method of the present invention can be obtained, for example, by a method comprising at least the following steps.

[0030] a) Hydrolyzing trimethylaluminum in a hydrocarbon solvent using a mixture of water and trimethylaluminum in a molar ratio of 0.4:1.0 to 1.0:1.0, preferably 0.5:1.0 to 1.0:1.0, and more preferably 0.6:1.0 to 0.9:1.0.

[0031] b) Separate the methylaluminoxane residue from the solution of methylaluminoxane in a hydrocarbon solvent.

[0032] c) Removal of unreacted trimethylaluminum from a solution of methylaluminoxane in a hydrocarbon solvent, preferably by distillation.

[0033] The hydrolysis in step a) can be carried out in any manner known to those skilled in the art and in any suitable container, i.e., by using a hydrocarbon solvent with a water content up to the solubility limit, an organic solvent in which water is dispersed, thereby allowing dispersion with high shear forces (e.g., high shear forces generated by a static or dynamic mixer).

[0034] The hydrolysis can be carried out in batches or continuously. In a preferred embodiment, the hydrolysis is carried out continuously, for example, using a loop reactor.

[0035] The temperature in step a) is typically in the range of -20°C to 50°C, preferably in the range of 0°C to 30°C.

[0036] The reaction pressure in step a) is typically in the range of 500 hPa to 5 MPa, preferably in the range of 800 hPa to 1 MPa, and more preferably at ambient pressure.

[0037] Suitable hydrocarbon solvents include aromatic and aliphatic hydrocarbons or mixtures thereof. Specific hydrocarbon solvents include toluene, o-xylene, m-xylene and p-xylene, mesitylene, n-hexane and methylcyclohexane, with toluene being preferred.

[0038] The weight ratio of the hydrocarbon solvent to trimethylaluminum used in step a) is typically in the range of 3:1 to 50:1, preferably in the range of 5:1 to 20:1, and more preferably in the range of 7:1 to 15:1.

[0039] During hydrolysis and due to dynamic equilibrium, a certain amount of unreacted trimethylaluminum remains in the reaction mixture obtained in step a).

[0040] Based on the total amount of trimethylaluminum used in step a), this amount can be, for example, in the range of 10% to 40%, preferably in the range of 10% to 30%.

[0041] In step b), the methylaluminoxane residue is separated from the solution of methylaluminoxane in a hydrocarbon solvent.

[0042] Separation is typically carried out via standard phase separation techniques, such as phase separation in settling tanks, decanters, or by centrifugation followed by removal of the methylaluminoxane solution.

[0043] If phase separation is carried out by gravity, the typical settling time is between 5 minutes and 12 hours, preferably between 5 minutes and 12 hours.

[0044] In step c), at least partially, unreacted trimethylaluminum present in the solution of methylaluminoxane in a hydrocarbon solvent after the separation of the methylaluminoxane residue in step b) is removed, preferably by distillation.

[0045] As used herein, the term distillation encompasses all techniques in which liquid compounds are separated via intermediate evaporation. This includes distillation, fractionation, rectification, flash evaporation, and similar techniques known to those skilled in the art for achieving this purpose.

[0046] The temperature in step c) is typically in the range of 5°C to 40°C, preferably in the range of 10°C to 25°C.

[0047] The reaction pressure in step c) is typically in the range of 5 hPa to 50 hPa, preferably in the range of 10 hPa to 30 hPa.

[0048] After step c), the trimethylaluminum content in the mixture can be, for example, in the range of 3% to 8%, based on the total amount of aluminum present in the mixture.

[0049] The trimethylaluminum content, as mentioned above, is measured by proton NMR, as specifically described in Donald W. Imhoff, Larry S. Simeral, Samuel A. Sangokoya, and James H. Peel; “Characterization of Methylaluminoxanes and Determination of Trimethylaluminum Using Proton NMR”; Organometallics 1998, 17, 10, 1941-1945.

[0050] In one embodiment, the content of the organic hydrocarbon solvent is, for example, 70 to 95 wt.%, preferably 85 to 95 wt.%.

[0051] Then, after removing the hydrocarbon solvent and adjusting the methylaluminoxane content, the methylaluminoxane solution is finally ready for storage, transportation, and further use.

[0052] The methylaluminoxane residue, preferably the methylaluminoxane residue obtained according to step b) of the above method, is reacted with at least one compound of formula (I) as defined above in the presence of a hydrocarbon solvent, wherein the same definitions, examples and preferred embodiments as mentioned above should also apply to organic hydrocarbon solvents.

[0053] For the avoidance of doubt, methylaluminoxane residues may contain a hydrocarbon solvent and a certain amount of methylaluminoxane in the hydrocarbon solvent, because typically 100% separation of insoluble methylaluminoxane residues is technically impractical due to the phase separation kinetics and swelling behavior of insoluble methylaluminoxane residues. However, as long as the parameter ranges given in the invention are met, these residues refer to methylaluminoxane residues and should be covered by the term methylaluminoxane residues.

[0054] The specific compounds of formula (I) include tri(n-octyl)aluminum and tri(n-hexyl)aluminum.

[0055] In the method according to the invention, the ratio of the methylaluminoxane residue to the compound of formula (I) with respect to their respective aluminum content is, for example, 1:1 to 200:1, and in another embodiment, 1.5:1.0 to 25.0:1.0.

[0056] The hydrocarbon solvent is typically and preferably the same as that described above for step i) of preparing the methylaluminoxane residue.

[0057] Typically, the amount of hydrocarbon solvent used is chosen such that the final concentration of the modified methylaluminoxane is in the range of 2 to 20 wt.%, preferably 5 to 15 wt.%.

[0058] The temperature in step ii) is typically in the range of 0°C to 50°C, preferably in the range of 10°C to 40°C.

[0059] The reaction typically takes place under ambient pressure or under pressure generated in the vessel used for the reaction during the reaction.

[0060] The reaction is typically carried out by adding at least one compound of formula (I), either pure or dissolved in a hydrocarbon solvent, to the methylaluminoxane residue and preferably by stirring, shaking, exposing the mixture to ultrasound or otherwise agitating the mixture to promote the reaction.

[0061] Reaction times typically range from 5 minutes to 24 hours, preferably from 1 hour to 16 hours. Longer reaction times are possible, but obviously offer no advantage.

[0062] As a result, the methylaluminoxane residue is at least partially dissolved and a modified methylaluminoxane solution is formed, which can then be used directly as obtained by the method according to the invention or subjected to a further separation step from the remaining methylaluminoxane residue.

[0063] In one embodiment, the content of modified methylaluminoxane in the solution obtained according to the invention is adjusted by adding or removing a hydrocarbon solvent.

[0064] This separation can be carried out in a manner completely similar to the separation described in step ii) of the preparation of methylaluminoxane residues.

[0065] The modified methylaluminoxane or its solution according to the present invention typically exhibits the following characteristics: 1 The molar ratio of methyl to non-methyl alkyl groups, determined by ¹H-NMR, is 200:1, preferably 100:2. Modified methylaluminoxanes and their solutions as defined above or obtainable by the method according to the invention are also covered by this invention.

[0066] The modified methylaluminoxane according to the present invention is particularly useful as a co-catalyst in polymerization (such as olefin polymerization).

[0067] Therefore, the present invention further covers the use of the modified methylaluminoxane according to the present invention as a co-catalyst or activator in polymerization reactions.

[0068] In one embodiment, the modified methylaluminoxane according to the invention is combined with at least one transition metal compound as a co-catalyst to form a polymerization catalyst, which is also covered by the invention.

[0069] In one embodiment, the polymerization catalyst of the present invention is prepared by absorbing and / or reacting a modified methylaluminoxane and / or transition metal compound according to the present invention with a solid support material.

[0070] In a preferred embodiment, the solid carrier material has a particle size in the range of 2 to 200 μm, preferably 5 to 100 μm.

[0071] Suitable solid support materials include, but are not limited to, inorganic compounds such as oxides, hydroxides, or mixtures of oxides and hydroxides of silicon, aluminum, magnesium, and titanium, such as silicon dioxide (SiO2), aluminum oxide (Al2O3), and titanium dioxide (TiO2). It will be apparent to those skilled in the art that the aforementioned specific materials still exhibit residual amounts of hydroxyl groups due to their chemical and structural properties.

[0072] Therefore, in one embodiment, the carrier material exhibits a surface hydroxyl content of 0.1 to 4.0 mmol / g, and preferably 1.0 to 3.0 mmol / g.

[0073] The amount of surface hydroxyl groups can be easily determined, for example, by measuring the amount of methane produced when a solid carrier material reacts with trimethylaluminum.

[0074] In another embodiment, the carrier material exhibits 50m 2 / g to 2.000m 2 / g, preferably 100m 2 / g to 1000m 2 / g and more preferably 200m 2 / g to 500m 2 / g of BET surface.

[0075] In another embodiment, the carrier material exhibits a thickness of 0.5 cm. 3 / g to 2.0cm 3 / g, preferably 0.8cm 3 / g to 1.8cm 3 / g and more preferably 1.2cm 3 / g to 1.8cm 3 / g pore volume.

[0076] As used herein, BET surface and pore volume were measured by nitrogen adsorption according to DIN ISO 9277:2010 (EN).

[0077] In order to produce the polymerization catalyst of the present invention, the amount of modified methylaluminoxane to be adsorbed onto or react with the solid support material can usually be determined by the amount of surface hydroxyl groups.

[0078] Typically, the amount of modified methylaluminoxane is in the range of 2 to 20 mmol / g solid carrier material, and preferably in the range of 4 to 10 mmol / g solid carrier material.

[0079] In order to produce the polymerization catalyst of the present invention, the amount of transition metal compound to be adsorbed onto or react with the solid support material can be controlled by the size and pore volume of the solid particulate support, the amount of surface hydroxyl groups and the amount of modified methylaluminoxane, and is typically in the range of 0.03 to 0.3 mmol / g solid support material and preferably in the range of 0.05 to 0.15 mmol / g solid support material.

[0080] The transition metal compound used in combination with the modified methylaluminoxane (either as is or on a solid support material) can be any known catalyst for olefin polymerization.

[0081] Such transition metal compounds include those represented by formula (II).

[0082] MR 1 R 2 R 3 R 4 (II)

[0083] Where M represents a transition metal; and where R 1 R 2 R 3 and R 4 One or two, three or four, preferably one or two, more preferably two, individually or together form an organic ligand, the organic ligand comprising at least one unsubstituted or substituted cyclopentadienyl anionic moiety or an unsubstituted or substituted indene anionic moiety or an unsubstituted or substituted fluorene anionic moiety; and wherein the remaining residue R 1 R 2 R 3 and R 4 Each member independently chooses from the following groups: C1-C 20 -alkyl, C1-C 20 -alkoxy group, C6-C 20 -Aryloxy group, C7-C 20 -Aryl group, (C1-C 20 )-trialkylsilyl, (C1-C 20 )-alkylamide, (C1-C 20 )-alkylimides, hydrides, and halide ions such as chloride, bromide, and iodide ions.

[0084] In a preferred embodiment, M in formula (II) represents titanium, zirconium, hafnium, chromium, vanadium, manganese, iron, cobalt, nickel, and palladium, wherein titanium, zirconium, chromium, iron, and nickel are preferred, and zirconium and hafnium are even more preferred.

[0085] In an exemplary embodiment, the transition metal compound of formula (II) includes bis(cyclopentadienyl)-zirconium chloride monohydride, bis(cyclopentadienyl)-zirconium bromide monohydride, bis(cyclopentadienyl)-methylzirconium hydride, bis(cyclopentadienyl)ethylzirconium hydride, bis(cyclopentadienyl)phenylzirconium hydride, bis(cyclopentadienyl)-benzylzirconium hydride, bis(cyclopentadienyl)-neopentylzirconium hydride, bis-(methylcyclopentadienyl)-zirconium chloride monohydride, and bis... (Indenyl-)zirconia hydride, bis(cyclopentadienyl-)zirconia dichloride, bis-(cyclopentadienyl)-zirconia dibromide, bis(cyclopentadienyl)-methylzirconia, bis(cyclopentadienyl)ethylzirconia, bis(cyclopentadienyl)-cyclohexylzirconia, bis(cyclopentadienyl)-phenylzirconia, bis(cyclopentadienyl)-benzylzirconia, bis(methylcyclopentadienyl)-zirconia dichloride, bis(dimethylcyclopentadienyl)-zirconia dichloride, bis... (n-Butylcyclopentadienyl)-zirconium dichloride, bis(indenyl)zirconium dichloride, bis(indenyl)zirconium dibromide, bis(cyclopentadienyl)-dimethylzirconium, bis(cyclopentadienyl)-diphenylzirconium, bis(cyclopentadienyl)-dibenzylzirconium, bis(cyclopentadienyl)-methoxyzirconium chloride, bis(cyclopentadienyl)-ethoxyzirconium chloride, bis(methylcyclopentadienyl)-ethoxyzirconium chloride, bis(cyclopentadienyl)-phenoxyzirconium chloride, and bis(fluorenyl) )-Zirconium dichloride, ethylene-bis(indenyl)dimethylzirconium, ethylene-bis(indenyl)diethylzirconium, ethylene-bis(indenyl)diphenylzirconium, ethylene-bis(indenyl)methylzirconium chloride, ethylene-bis(indenyl)ethylzirconium chloride, ethylene-bis(indenyl)methyl bromide, ethylene-bis(indenyl)zirconium dichloride, ethylene-bis(indenyl)zirconium bromide and bis(n-butylcyclopentadienyl)zirconium dichloride and all hafnium analogs of the above compounds.

[0086] In another exemplary embodiment, the transition metal compound of formula (II) includes dimethylsilyl-bis-(1-indenyl)-zirconium dichloride (IV), dimethylsilyl-bis(2-methylindenyl)zirconium dibromide, dimethylsilyl-bis(2-methyl-4-phenylindenyl)zirconium dichloride, dimethylsilyl-bis[2-methyl-4-(1-naphthyl)indenyl]zirconium difluoride, dimethylsilyl-bis[2-methyl-4-(1-naphthyl)indenyl]hafnium dichloride, dimethylsilyl-bis(2-methyl-4,5-benzoindenyl)zirconium dichloride, dimethylsilyl-bis(4,5-benzoindenyl)zirconium dichloride, and dimethylsilyl-bis(2-methyl-4,6-diisopropylindenyl)zirconium difluoride. Zirconium dichloride, dimethylsilanediyl-bis(2-ethylindene)zirconium dichloride, dimethylsilanediyl-bis(2-ethyl-4-phenylindene)zirconium dichloride, dimethylsilanediyl-bis(2-ethyl-4-phenylindene)hafnium dichloride, dimethylsilanediyl-bis[2-ethyl-4-(1-naphthyl)indene]zirconium dichloride, dimethylsilanediyl-bis(2-ethyl-4,5-benzoindene)zirconium dichloride, dimethylsilanediyl-bis(4,5-benzoindene)zirconium dichloride, dimethylsilanediyl-bis(2-ethyl-4,6-diisopropylindene)zirconium dichloride, dimethylsilanediyl-bis(2-ethyl-4,6-dimethylindene)zirconium dichloride, dimethylsilanediyl-bis(2,4,6-trimethylindene) Zirconium dichloride, dimethylsilanediyl-bis(2,4,6-trimethylindenyl)hafnium dichloride, (1H-inden-2-yl)dimethyl-silyl-(2,3,4,5-tetramethylcyclopentan-2,4-dienyl)zirconium dichloride, dimethyl-silyl-(2-phenyl-1H-inden-1-yl)(2,3,4,5-tetramethylcyclopentan-2,4-dienyl)zirconium dichloride, dimethyl-silyl-(2-methyl-4-phenyl-1-H-inden-1-yl)(2,3,4,5-tetramethylcyclopentan-2,4-dienyl)zirconium dichloride, dimethyl-silyl-(3-phenyl-1-H-inden-1-yl)(2,3,4,5-tetramethylcyclopentan-2,4-dienyl)zirconium dichloride, (2- Isopropyl-1H-inden-1-yl)dimethyl-silyl-(2,3,4,5-tetramethylcyclopentan-2,4-dienyl)zirconium dichloride, (1H-inden-2-yl)dimethyl(2,3,4,5-tetramethyl-cyclopentan-2,4-dienyl)zirconium dichloride, dimethyl-silyl-(1-methyl-2-phenyl-1H-inden-3-yl)(2,3,4,5-tetramethyl-cyclopentan-2,4-dienyl)zirconium dichloride, dimethyl-silyl-(1-methyl-2-phenyl-1H-inden-3-yl)(2,3,4,5-tetramethyl-cyclopentan-2,4-dienyl)hafnium dichloride, (1H-inden-2-yl)dimethyl-silyl-(2,3,4,5-tetramethyl-cyclopentan-2,4-dienyl)hafnium dichloride, (1H-inden-2-yl)dimethyl-silyl-(2,3,4,5-tetramethyl-cyclopentan-2,4-dienyl)hafnium dichloride, (1H-inden-2-yl)dimethyl-silyl-(2,3,4,5-tetramethyl-cyclopentan-2,Hafnium dichloride (2,3,4,5-dienyl)dichloride, hafnium dichloride (2,3,4,5-tetramethylcyclopentan-2,4-dienyl)dichloride, hafnium dichloride (2,3,4,5-tetramethylcyclopentan-2,4-dienyl)dichloride, hafnium dichloride (2,3,4,5-tetramethylcyclopentan-2,4-dienyl)dichloride, hafnium dichloride (3,3,4,5-tetramethylcyclopentan-2,4-dienyl)dichloride, hafnium dichloride (2 ... Hafnium dichloride (4,5-tetramethylcyclopentan-2,4-dienyl)dichloride, hafnium dichloride (2-isopropyl-1H-inden-1-yl)dimethyl-silyl-(2,3,4,5-tetramethyl-cyclopentan-2,4-dienyl)dichloride, and zirconium dichloride (2,5-dimethyl-7H-cyclopentan[1,2-b;4,3-b']dithiophene-7-yl)-(2,4,7-trimethyl-1H-inden-1-yl)-zirconium dichloride.

[0087] In one embodiment, the polymerization catalyst of the present invention is prepared by contacting at least one transition metal compound, the modified methylaluminoxane according to the present invention, and a solid support material in a hydrocarbon.

[0088] In one embodiment, the modified methylaluminoxane according to the invention is contacted with a solid carrier material before these components are contacted with at least one transition metal compound.

[0089] The polymerization catalyst according to the invention is typically prepared at a temperature of 0°C to 200°C, and preferably at a temperature of 10°C to 100°C.

[0090] The contact time for preparing the polymerization catalyst is typically 0.5 to 24 hours, preferably 0.5 to 2 hours.

[0091] Suitable hydrocarbons for preparing the polymerization catalyst according to the invention include aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, n-octane, and isooctane; cyclic aliphatic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane, and cycloheptane; and aromatic hydrocarbons such as benzene, toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene; and any mixture of the above hydrocarbons, wherein n-hexane, n-heptane, n-octane, cyclohexane, methylcyclohexane, and toluene are particularly preferred.

[0092] The polymerization catalyst according to the invention can be used in two different ways, either in a homogeneous system or in a heterogeneous system on a solid support material as described above, as a polymerization catalyst.

[0093] Polymerization can be carried out in a manner known per se, either as gas-phase polymerization or liquid-phase polymerization, as bulk polymerization or continuous polymerization.

[0094] Suitable monomers for copolymerization, either individually or in combination, include α-olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-decene, 1-hexadecene, 1-octadecene, and 1-eicosene; halogen-substituted olefins such as difluoroethylene, trifluoroethylene, tetrafluoroethylene, and hexafluoropropylene; and cycloolefins such as cyclopentene, cyclohexene, and norbornene.

[0095] The following examples will further illustrate the invention in detail:

[0096] Example

[0097] The methylaluminoxane residue obtained from a commercial plant using toluene as a hydrocarbon solvent according to the method disclosed above was analyzed. The methylaluminoxane residue contained 16.8 wt.% methylaluminoxane residue, 0.3 wt.% trimethylaluminum, and 83.2 wt.% toluene. The aluminum content was 47.0 wt.% by dry weight, and the molar ratio of methyl to aluminum was 1.07.

[0098] After the sample was decomposed with acetate buffer, the aluminum content was determined by complexometric titration with EDTA and dimethylbinaphthylamine as an indicator.

[0099] The molar ratio of methyl groups to aluminum was determined by 1H-NMR.

[0100] Examples 1-6

[0101] Pure trialkylaluminum or other organometallic compounds were added to the methylaluminoxane residue thus obtained in the amounts listed in Table 1 below, and the mixture was stirred overnight (i.e., 16 h) at 20 °C. The insoluble fraction, i.e., the content of unreacted methylaluminum residue, was measured again. The results are summarized in Table 1.

[0102] Table 1

[0103]

[0104] *MAO = Methylaluminoxane, **TOA = Tri-n-octylaluminum, ***Triisobutylaluminum

[0105] ****TDDA = Tri-n-dodecyl aluminum, *****DIBAC = Isobutyl aluminum chloride

[0106] ******BOMAG = Butyl-Octylated Magnesium

[0107] As is evident from Table 1, only tri-n-octylaluminum and tri-n-dodecylaluminum can significantly convert methylaluminoxanes to form modified methylaluminoxanes, while triisobutylaluminum is much less efficient, and diisobutylaluminum chloride and butyl-octylmagnesium fail to achieve this goal.

[0108] Example 7

[0109] Preparation of polymerization catalysts using the modified methylaluminoxane of the present invention.

[0110] 4.4 g of tri-n-octylaluminum (TOA) (corresponding to 3% aluminum present in the methylaluminoxane residue) was added to 122.3 g of a methylaluminoxane residue having a total Al content of 8.74 wt% and a methyl to Al molar ratio of 1.05 as determined by 1H-NMR. This methylaluminoxane residue was obtained from a commercial plant and used toluene as the hydrocarbon solvent according to the method disclosed above. The resulting mixture was stirred at 40 °C for 8 h and then stirred at room temperature for another 16 h. After sedimentation, the supernatant was decanted from the small amount of remaining gel-like residue and analyzed. The resulting modified methylaluminoxane solution had an Al content of 8.20 wt% and a methyl to Al molar ratio of 1.40. Note that the methyl to Al molar ratio was determined here by hydrolysis first with n-heptanol and then with a 10 wt% aqueous sulfuric acid solution and calculated from the measured volume of gas released from the sample during such hydrolysis (normalized to standard conditions). 11.0g of silica gel (PQ ES70X, with an average particle size of 51μm and a density of 320m) was used. 2 A 1 / g BET surface concentration was suspended in 125 ml of toluene in a 500 ml double-walled reactor. 28.9 g of the modified methylaluminoxane solution was added via a dropping funnel at 20 °C over 40 minutes. After metered addition, the resulting mixture was heated to reflux for 4 h and then cooled to 20 °C. Finally, 0.323 g of bis(n-butylcyclopentadienyl)zirconium dichloride was added and the suspension was stirred for 2 h. The pale yellow solid was removed via glass frit and dried under vacuum for 8 h.

[0111] Example 8

[0112] Preparation of polymerization catalysts using commercial methylaluminoxane

[0113] 11.0g of silica gel (PQ ES70X, with an average particle size of 51μm and a density of 320m) was used. 2(BET surface area / g) was suspended in 125ml of toluene in a 500ml double-walled reactor. 18.2g of a commercial methylaluminoxane solution (AXION CA 1330, having an Al content of 13.46 wt.-% and a methyl to aluminum molar ratio of 1.67 as determined by decomposition gas formation as described in Example 7 above and a methyl to aluminum molar ratio of 1.59 as determined by 1H-NMR) was added via a dropping funnel at 20°C over 40 minutes. After metered addition, the resulting mixture was heated to reflux for 4h and then cooled to 20°C. Finally, 0.334g of bis(n-butylcyclopentadienyl)zirconium dichloride was added and the suspension was stirred for 2h. The pale yellow solid was removed via glass frit and dried under vacuum for 8h.

[0114] The analytical results of the catalysts from Examples 7 and 8 are given in Table 2.

[0115] Table 2: Analysis Results

[0116]

[0117] Examples 9 and 10: Aggregation

[0118] The catalysts prepared according to Examples 7 and 8 were used in the polymerization reaction. A certain amount of the catalyst, as shown in Table 3, was dispersed in 100 ml of hexane as a solvent in the polymerization reactor, and then subjected to an ethylene pressure of 1 MPa at 80 °C for 40 minutes. The obtained polyethylene was then weighed, and the catalyst performance was calculated. The results are also given in Table 3.

[0119] Table 3: Analysis Results

[0120]

[0121] Clearly, the modified methylaluminoxane obtained from the residue of methylaluminoxane production according to the present invention can be used as an effective co-catalyst in polymerization reactions.

Claims

1. A method for preparing modified methylaluminoxane, the method comprising at least making a methylaluminoxane having the following... i) An aluminum content of 30 to 50 wt.-%, preferably 40 to 50 wt.-%, relative to dry weight. ii) Preferably, the molar ratio of methyl to aluminum is 0.6 to 1.4, more preferably 0.7 to 1.3, and even more preferably 0.90 to 1.30 and even more preferably 1.00 to 1.30, as determined by 1H-NMR. These types of methylaluminoxanes are referred to below as "methylaluminoxane residues". Step AIR3(I) involves contacting at least one compound of formula (I) with a hydrocarbon solvent in the presence of the solvent. Where R represents C6-C 18 Alkyl, more preferably C8-C 16 Alkyl, and even more preferably C8-C 12 alkyl.

2. The method according to claim 1, wherein, The methylaluminoxane residue used in step i) is obtained by a method comprising at least the following steps: a) Hydrolyzing trimethylaluminum in a hydrocarbon solvent using a mixture of water and trimethylaluminum in a molar ratio of 0.4:1.0 to 1.0:1.0, preferably 0.5:1.0 to 1.0:1.0, and more preferably 0.6:1.0 to 0.9:1.

0. b) Separate the methylaluminoxane residue from the solution of methylaluminoxane in the hydrocarbon solvent. c) At least partially remove unreacted trimethylaluminum, preferably by distillation.

3. The method according to claim 2, wherein, The temperature in step a) is in the range of -20°C to 50°C, preferably in the range of 0°C to 30°C, and / or preferably the reaction pressure in step a) is in the range of 500 hPa to 5 MPa, preferably in the range of 800 hPa to 1 MPa.

4. The method according to claim 2, wherein, The hydrocarbon solvent is selected from the group consisting of aromatic and aliphatic hydrocarbons or mixtures thereof.

5. The method according to any one of claims 1 to 4, wherein, The compounds of these formulas (I) are selected from the group consisting of tri(n-octyl)aluminum and tri(n-hexyl)aluminum, preferably tri(n-octyl)aluminum.

6. The method according to any one of claims 1 to 5, wherein, The ratio of the methylaluminoxane residue to the compounds of these formulas (I) with respect to their respective aluminum content is from 1:1 to 200:1, and in another embodiment from 1.5:1.0 to 25.0:1.

0.

7. The method according to any one of claims 1 to 6, wherein, The reaction time is 5 minutes to 24 hours, preferably 1 hour to 16 hours.

8. A modified methylaluminoxane available according to any one of claims 1 to 7.

9. The modified methylaluminoxane according to claim 8, wherein it preferably has the following characteristics as described above: 1 The molar ratio of methyl to non-methyl alkyl groups determined by H-NMR is 200:1, preferably 100:

2.

10. The use of the modified methylaluminoxane according to claim 8 or 9 as a co-catalyst or activator in polymerization, preferably as a co-catalyst or activator in olefin polymerization.

11. The use according to claim 10, wherein, The modified methylaluminoxane according to claim 8 or 9 is used as a cocatalyst or activator in combination with at least one transition metal compound.

12. A polymerization catalyst comprising the modified methylaluminoxane according to claim 8 or 9, and preferably additionally at least one transition metal compound.

13. A method for the polymerization of olefins, preferably for the polymerization of ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-decene, 1-hexadecene, 1-octadecene, and 1-eicosene; halogen-substituted olefins such as difluoroethylene, trifluoroethylene, tetrafluoroethylene, and hexafluoropropylene; and cyclic olefins such as cyclopentene, cyclohexene, and norbornene, or any mixture thereof, wherein a modified methylaluminoxane according to claim 8 or 9 or a polymerization catalyst according to claim 12 is used.

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