Bis (di-, tri- or tetra-substituted-cyclopentadienyl)-zirconium dihalides

This invention relates to a process for producing polyolefins using a certain bis (tri- substituted-cyclopentadienyl)zirconiumdichloride as catalyst.

Since a catalyst comprising a bis(di-substituted-cyclopentadienyl)zirconium dichloride and methylaluminoxane was found to have high activity for polymerizing olefins [ Japanese Patent Kokai No. 19309 (1983), and Makromol. Chem. Rapid Commun, <u>4</u>, 417 (1983) ], various types of zirconium compounds have been investigated as a component of olefin-polymerization catalysts.

As examples of cyclopentadienyl zirconium compounds having sustituent groups on the cyclopentadienyl ring so far synthesized, may be mentioned bis(methylcyclopentadienyl)zirconium dichloride [ J. Chem. Soc. Dalton Trans., 805 (1981) ], bis (pentamethylcyclopentadienyl)zirconium dichloride [ J. Amer. Chem. Soc., <u>100,</u> 3078 ( 1978 )] and (pentamethylcyclopentadienyl)-(cyclopentadienyl)zirconium dichloride [ J. Amer. Chem. Soc., <u>106,</u> 6355 (1984)].

Use of compounds represented by the general formula of (C₅R^'_m)_pR^"_s, (C₅R^'_m)MeQ_3-p or R^"_s (C₅R^'_m)₂MeQ as catalysts is described in Japanese Patent Kokai No.35006 through No.35008 ( 1985 ) and No.296008 ( 1986 ), but no description can be found at all on the synthesis and properties of these compounds.

Japanese Patent Kokai No.236804 ( 1986 ) describes a process for producing polyethylene wax with unsaturated bonds at terminals, but no description is made on the details of said unsaturated bonds.

These conventional Kaminsky catalysts have the problems that the yield and molecular weight of resultant polyolefins are not sufficiently high, and that there is no controlling the structure of said unsaturated bonds at terminals.

Journal of Magnetic Resonance, vol. 37, pages 441 to 448, describes the proton and carbon NMR spectra of alkyl-substituted titanocene and zirconocene dichlorides.

EP-A-0 128 045 describes a process for producing polyethylene having a broad molecular weight distribution using a catalyst system comprising (a) at least two different metallocenes which are mono-, di- or tri-cyclopentadienyl derivatives of a group 4b, 5b and 6b transition metal each having different propagation and termination rate constants for ethylene polymerizations and (b) an alumoxane.

We succeeded in preparing the aforementioned zirconium compounds having, as ligand tri- substituted-cyclopentadienyl radicals ( compounds useful as a component of polyolefin-producing catalysts ) through the route shown later equations (1) and (2), and also proved the intended effectiveness of these compounds.

Thus, we found that catalysts comprising the transition metal compound as mentioned above and a specific aluminoxane catalyze polymerization of olefins to produce polyolefins with controlled terminal groups (vinylidene type ), and accomplished this invention based on these findings.

Thus the present invention provides a process for producing polyolefins by using a catalyst which contains, as effective components, (A) only one transition metal compound and (B) an aluminoxane represented by the following general formula [VII] or [VIII]: <chemistry id="chem0001" num="0001"><img file="EP0283739B2_D0001.tif" /></chemistry><chemistry id="chem0002" num="0002"><img file="EP0283739B2_D0002.tif" /></chemistry>    in which m is an integer of 4 to 20; and R² denotes a hydrocarbyl radical, characterized in that said transition metal compound (A) is a compound represented by the following general formula [VI]:         (R¹_n -C₅H_5-n)₂MX₂     [VI]    wherein R¹_n -C₅H_5-n denotes a substituted-cyclopentadienyl radical; n is an integer of 2 to 4; R¹ stands for an alkyl radical of 1 to 5 carbon atoms; M expresses titanium, zirconium, vanadium or hafnium; and X is a halogen atom, said transition metal compound (A) being a compound having two di-substituted-cyclopentadienyl radicals or being a compound having two tri-substituted cyclopentadienyl radicals or being a compound having two tetra-substituted-cyclopentadienyl radicals, selected from bis(1,2,4-trimethylcyclopentadienyl)zirconium dichloride.

The catalyst used according to this invention and the process for producing polyolefins using the same are as specified below. <ul id="ul0001" list-style="none"><li>(1) Catalyst for the synthesis of polyolefins which contains, as effective components, (A) only one transition metal compound as defined in claim 1 and (B) an aluminoxane represented by the following general formula [VII] or [VIII], <chemistry id="chem0003" num="0003"><img file="EP0283739B2_D0003.tif" /></chemistry><chemistry id="chem0004" num="0004"><img file="EP0283739B2_D0004.tif" /></chemistry> ( wherein m is an integer of 4 to 20; and R² denotes a hydrocarbyl radical ).</li><li>(2) Process for producing polyolefins by using a catalyst described in (1), above. Figure 1 shows IR spectrum of the compound used according to the invention ; Figure 2 shows NMR spectrum of this compound and Figures 3 through 4 show IR spectra of atactic polypropylenes obtained by polymerization of propylene using the catalyst of this invention and a conventional catalyst. Compounds (R<maths id="math0001" num=""><math display="inline"><mrow><mfrac linethickness="0"><mrow><mtext>1</mtext></mrow><mrow><mtext>2</mtext></mrow></mfrac></mrow></math><img file="EP0283739B2_D0005.tif" /></maths> - C₅H₃)₂ ZrX₂ may be prepared through the synthetic route shown below <maths id="math0002" num="(1)"><math display="block"><mrow><msubsup><mrow><mtext>R</mtext></mrow><mrow><mtext>2</mtext></mrow><mrow><mtext>1</mtext></mrow></msubsup><msub><mrow><mtext>-C</mtext></mrow><mrow><mtext>5</mtext></mrow></msub><msub><mrow><mtext>H</mtext></mrow><mrow><mtext>4</mtext></mrow></msub><mtext> + n-BuLi →</mtext><mspace linebreak="newline" /><msubsup><mrow><mtext>Li(R</mtext></mrow><mrow><mtext>2</mtext></mrow><mrow><mtext>1</mtext></mrow></msubsup><msub><mrow><mtext>-C</mtext></mrow><mrow><mtext>5</mtext></mrow></msub><msub><mrow><mtext>H</mtext></mrow><mrow><mtext>3</mtext></mrow></msub><mtext>) + n-Butane</mtext></mrow></math><img file="EP0283739B2_D0006.tif" /></maths><maths id="math0003" num="(2)"><math display="block"><mrow><msubsup><mrow><mtext>2Li(R</mtext></mrow><mrow><mtext>2</mtext></mrow><mrow><mtext>1</mtext></mrow></msubsup><msub><mrow><mtext>-C</mtext></mrow><mrow><mtext>5</mtext></mrow></msub><msub><mrow><mtext>H</mtext></mrow><mrow><mtext>3</mtext></mrow></msub><msub><mrow><mtext>) + ZrX</mtext></mrow><mrow><mtext>4</mtext></mrow></msub><mtext> →</mtext><mspace linebreak="newline" /><msubsup><mrow><mtext>(R</mtext></mrow><mrow><mtext>2</mtext></mrow><mrow><mtext>1</mtext></mrow></msubsup><msub><mrow><mtext>-C</mtext></mrow><mrow><mtext>5</mtext></mrow></msub><msub><mrow><mtext>H</mtext></mrow><mrow><mtext>3</mtext></mrow></msub><msub><mrow><mtext>)</mtext></mrow><mrow><mtext>2</mtext></mrow></msub><msub><mrow><mtext>ZrX</mtext></mrow><mrow><mtext>2</mtext></mrow></msub><mtext> + 2LiX</mtext></mrow></math><img file="EP0283739B2_D0007.tif" /></maths>wherein R¹, R<maths id="math0004" num=""><math display="inline"><mrow><mfrac linethickness="0"><mrow><mtext>1</mtext></mrow><mrow><mtext>2</mtext></mrow></mfrac></mrow></math><img file="EP0283739B2_D0008.tif" /></maths> -C₅H₃ and X are as defined above. The same applies to the trisubstituted compound used in the invention. </li></ul>

Tri-substituted cyclopentadienes are of the following two types: ( 1,2, 3-R<maths id="math0005" num=""><math display="inline"><mrow><mfrac linethickness="0"><mrow><mtext>1</mtext></mrow><mrow><mtext>2</mtext></mrow></mfrac></mrow></math><img file="EP0283739B2_D0009.tif" /></maths>C₅H₃ ) <chemistry id="chem0005" num="0005"><img file="EP0283739B2_D0010.tif" /></chemistry> ( 1,2,4-R<maths id="math0006" num=""><math display="inline"><mrow><mfrac linethickness="0"><mrow><mtext>1</mtext></mrow><mrow><mtext>3</mtext></mrow></mfrac></mrow></math><img file="EP0283739B2_D0011.tif" /></maths>-C₅H₃ ) <chemistry id="chem0006" num="0006"><img file="EP0283739B2_D0012.tif" /></chemistry> 1,2,4-isomers shown above are used in this invention.

Substituted cyclopentadienes of this type can be prepared by known methods described in Bull. Soc. Chim. Fr., 2981 ( 1970 ), J. Chem. Soc., 1127 ( 1952 ), Tetrahedron, <u>19,</u> 1939 ( 1963 ), ibid., <u>21</u>, 2313 ( 1965 ) and J. Org. Chem., <u>36</u>, 3979 ( 1971 ).

These substituted cyclopentadienes may be converted to the corresponding Li compounds by reaction with an alkyl lithium to be subjected to the succeeding reaction. Alternatively, substituted cyclopentadienyl potassium or substituted cyclopentadienyl sodium may also be used similarly.

Reaction of ZrX₄ with Li(R<maths id="math0007" num=""><math display="inline"><mrow><mfrac linethickness="0"><mrow><mtext>1</mtext></mrow><mrow><mtext>3</mtext></mrow></mfrac></mrow></math><img file="EP0283739B2_D0013.tif" /></maths>-C₅H₂) may be carried out in an ether solvent, preferably tetrahydrofuran ( THF ) or 1,2-dimethoxyethane, at a temperature in the range from -20 to 100°C ( preferably from 0 to 30°C). The preferred mole ratio of Li(R<maths id="math0008" num=""><math display="inline"><mrow><mfrac linethickness="0"><mrow><mtext>1</mtext></mrow><mrow><mtext>3</mtext></mrow></mfrac></mrow></math><img file="EP0283739B2_D0014.tif" /></maths>-C₅H₂) to ZrX₄ is in the range from 1.9 to 3.0, most preferably from 2.0 to 2.4. The reaction is complete in three days at room temperature, and can be completed in shorter periods at elevated temperatures. The reaction products may be purified by recrystallization or sublimation.

Aluminoxane (B), which is the other component of the catalyst of this invention, is an organo-aluminum compound represented by the general formula [VII] or [VIII]. R² is a hydrocarbyl radical, such as methyl, ethyl, propyl and butyl ( preferably methyl or ethyl ), and m is an integer of 4 to 20, preferably 6 to 20, most preferably 10 to 20. These compounds may be prepared by known methods, for example, by adding a trialkyl aluminum to a suspension of a compound with absorbed water or a salt with water of crystallization (e.g., hydrated cupric sulfate and hydrated aluminum sulfate ) in a hydrocarbon medium.

The olefins to be used for polymerization by the catalyst of this invention are α-olefins, such as ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene. These may be polymerized either alone or in combination. In addition, the catalyst of this invention may be used for copolymerization of such an α-olefin with a diene, such as butadiene, 1,4-hexadiene, 1,4-pentadiene, 1,7-octadiene, 1,8-nonadiene and 1,9-decadiene; or with a cyclic olefin, such as cyclopropane, cyclobutene, cyclohexene, norbornene and cyclopentadiene.

Polymerization may be effected by any of the suspension, solution and gas-phase polymerization methods. As the solvent in solution polymerization, may be used an alifatic hydrocarbon, such as butane, pentane, hexane, octane, decane, dodecane, hexadecane and octadecane; an alicyclic hydrocarbon, such as cyclopentane, methylcyclopentane, cyclohexane and cyclooctane; an aromatic hydrocarbon, such as benzene, toluene and xylene; or a petroleum fraction, such as gasoline, kerosene and gas oil. Of these, aromatic hydrocarbons are the most preferred. Polymerization is carried out at a temperature in the range from -50 to 230°C ( preferably from -20 to 200°C ) under an olefin pressure in the range from normal pressure to 50 Kg/cm²G. Molecular weight of polyolefins can be modified by known techniques, for example, by selction of proper polymerization temperature or by introduction of hydrogen gas into the reaction system.

In carrying out olefin polymerization, the two components of catalyst (A) and (B) (only one transition metal compound and an aluminoxane ) may be added to the reaction system after being intimately mixed together, or may be separately introduced to the reaction system. In both cases, there is no specific limitation upon the mole ratio and concentration of the two components in the system. But it is preferable that the concentration of component (A) be in the range from 10^-4 to 10^-9 mol/l and the Al/transition-metal-atom mole ratio be 100 or higher ( most preferably 1000 or higher ).

The structure of terminal unsaturated bond in polyolefins produced by the use of catalyst of this invention can be identified by IR analysis. For example, vinylidene group can be detected by the presence of absorption peaks at 3095 to 3077cm^-1, 1790 to 1785cm^-1, 1661 to 1639cm^-1 and 892 to 883cm^-1.

Use of a catalyst of this invention, which comprises an aluminoxane and only one transition metal compound having two, tri-substituted cyclopentadienyl radicals, gives polyolefins with controlled structure of terminal groups ( vinylidene type ).

As will be apparent from the following Examples and Comparative Examples, the catalyst of this invention is higher in activity and gives polyolefins with higher molecular weight, compared with conventional catalyst systems.

The following Examples will further illustrate the invention.

Example 1

[ Bis(1,2,4-trimethylcyclopentadienyl)zirconium dichloride ]

The reaction was carried out in an inert gas atmosphere throughout its entire course. The solvent used for reaction had been previously dehydrated. To a solution of 5.5 g ( 51 millimoles ) 1,2,4-trimethylcyclopentadiene in 150 ml tetrahydrofuran placed in a glass reaction vessel (500 ml ), was added dropwise 36 ml of a 15% solution of n-butyl lithium in hexane, the mixture was stirred at room temperature for one hour, the resulting white suspension of 1,2,4-trimethylcyclopentadienyl lithium was cooled to 0°C, and 5.9 g ( 25 millimoles ) zirconium tetrachloride was added in five portions.

The temperature of reaction mixture was slowly raised to room temperature, stirring was continued for 48 hours, the solvent was distilled off under reduced pressure from the yellow solution containing white precipitate ( LiCI ), and the residue was extracted with 300 ml dichloromethane. The yellow extract was cocnetrated, pentane was added, and the resulting mixture was cooled to -30°C, giving 4.0 g of white crystals. The crude product thus obtained was purified by sublimation ( 130-140°C/1mmHg ), affording pure product ( yield: 3.5 g, 36 % ). Its properties are shown below, in which IR spectrum and ¹H-NMR spectrum were measured by the KBr and CDCI₃ ( 100 MHz ) methods, respectively. Melting point:    172-173°C <tables id="tabl0001" num="0001"><table frame="all"><tgroup cols="3" colsep="1" rowsep="0"><colspec colnum="1" colname="col1" colwidth="52.50mm" /><colspec colnum="2" colname="col2" colwidth="52.50mm" /><colspec colnum="3" colname="col3" colwidth="52.50mm" /><thead valign="top"><row rowsep="1"><entry namest="col1" nameend="col3" align="left">Elemental analysis ( C₁₆H₂₂Cl₂Zr)</entry></row></thead><tbody valign="top"><row><entry namest="col1" nameend="col1" align="left">Calcd. (%)</entry><entry namest="col2" nameend="col2" align="left">C: 51.05,</entry><entry namest="col3" nameend="col3" align="left">H: 5.89</entry></row><row rowsep="1"><entry namest="col1" nameend="col1" align="left">Found (%)</entry><entry namest="col2" nameend="col2" align="left">C: 51.02,</entry><entry namest="col3" nameend="col3" align="left">H: 5.75</entry></row></tbody></tgroup></table></tables> IR spectrum :    As shown in Figure 1 NMR spectrum :    As shown in Figure 2

Example 2 [ Polymerization ]

A stainless steel autoclave ( capacity: 1.5 liters ), with its internal air thoroughly displaced by nitrogen gas, was charged with 450 ml of pure toluene, 6.3 millimoles of methylaluminoxane ( M.W.: 909; product of Toyo Stauffer Chemical Co. ) and 0.02 millimole of bis(1,2,4-trimethylcyclopentadienyl)zirconium dichloride prepared in Example 1 in that order, and the mixture was heated to 50°C.

Propylene was then introduced continuously to the autoclave so that the internal pressure was maintained at 8 Kg/cm²G, and polymerization was continued under this condition for 1.5 hours. At the end of reaction, methanol was added to decompose the catalyst and atactic polypropylene formed was collected and dried ( yield: 260 g ). Its IR spectrum showed peaks at 1651cm^-1 and 887cm^-1, indicating vinylidene-type terminal structure.

Comparative Example 1 [ Polymerization ]

A stainless steel autoclave ( capacity: 1.5 liters ), with its internal air thoroughly displaced by nitrogen gas, was charged with 450 ml of pure toluene, 6.3 millimoles of methylaluminoxane ( M.W.: 909; product of Toyo Stauffer Chemical Co. ) and 0.02 millimole of bis(pentamethylcyclopentadienyl)zirconium dichloride in that order, and the mixture was heated to 50°C.

Propylene was then introduced continuously to the autoclave so that the internal pressure was maintained at 8 Kg/cm²G, and polymerization was continued under this condition for four hours. At the end of reaction, methanol was added to decompose the catalyst and atactic polypropylene formed was collected and dried ( yield: 210 g ). Its IR spectrum showed the presence of peaks at 1639cm^-1, 991cm^-1 and 910cm^-1, indicating vinyl-type terminal structure.

IR absorption spectra of the atactic polypropylenes obtained in Example 2 and in Comparative Example 1 are shown in Figures 3 and 4, respectively; ¹³C-NMR data for the polymer of Example 2 are shown in Table 1; and GPC data for the polymers of Example 2 and of Comparative Example 1 are shown in Table 2. <tables id="tabl0002" num="0002"><img file="EP0283739B2_D0015.tif" /></tables><tables id="tabl0003" num="0003"><img file="EP0283739B2_D0016.tif" /></tables>

Example 3 [ Polymerization ]

A stainless steel autoclave ( capacity: 1.5 liters ), with its internal air thoroughly displaced by nitrogen gas, was charged with 450 ml of pure toluene, 6.3 millimoles of methylaluminoxane ( M.W.: 909; product of Toyo Stauffer Chemical Co.) and 0.02 millimole of bis(1,2,4-trimethylcyclopentadienyl)zirconium dichloride prepared in Example 1 in that order, and the mixture was heated to 50°C. Propylene was then introduced continuously to the autoclave so that the internal pressure was maintained at 8 Kg/cm²G, and polymerization was continued under this condition for 1.5 hours. At the end of reaction, methanol was added to decompose the catalyst and atactic polypropylene formed was collected and dried ( yield: 260 g ). The catalyst activity was 95 Kg/gZr•hr and the molecular weight of the polymer obtained was 13,000.

Comparative Example 2 [ Polymerization ]

A stainless steel autoclave ( capacity: 1.5 liters ), with its internal air thoroughly displaced by nitrogen gas, was charged with 450 ml of pure toluene, 6.3 millimoles of methylaluminoxane ( M.W.: 909; product of Toyo Stauffer Chemical Co. ) and 0.02 millimole of bis(cyclopentadienyl)zirconium dichloride in that order, and the mixture was heated to 50°C. Propylene was then introduced continuously to the autoclave so that the internal pressure was maintained at 8 Kg/cm²G, and polymerization was continued under this condition for four hours. At the end of reaction, methanol was added to decompose the catalyst and atactic polypropylene formed was collected and dried ( yield: 150 g ). The catalyst activity was 20 Kg/gZr•hr and the molecular weight of the polymer obtained was 1,300.

Comparative Example 3 [ Polymerization ]

A stainless steel autoclave ( capacity: 1.5 liters ), with its internal air thoroughly displaced by nitrogen gas, was charged with 450 ml of pure toluene, 6.3 millimoles of methylaluminoxane ( M.W.: 909; product of Toyo Stauffer Chemical Co. ) and 0.02 millimole of bis(pentamethylcyclopentadienyl)zirconium dichloride in that order, and the mixture was heated to 50°C. Propylene was then introduced continuously to the autoclave so that the internal pressure was maintained at 8 Kg/cm²G, and polymerization was continued under this condition for four hours. At the end of reaction, methanol was added to decompose the catalyst and atactic polypropylene formed was collected and dried ( yield: 210 g ). The catalyst activity was 28 Kg/gZr•hr and the molecular weight of the polymer obtained was 300.

Comparative Example 4 [ Polymerization ]

A stainless steel autoclave ( capacity: 1.5 liters ), with its internal air thoroughly displaced by nitrogen gas, was charged with 450 ml of pure toluene, 6.3 millimoles of methylaluminoxane ( M.W.: 909; product of Toyo Stauffer Chemical Co. ) and 0.02 millimole of bis(methylcyclopentadienyl)zirconium dichloride in that order, and the mixture was heated to 50°C. Propylene was then introduced continuously to the autoclave so that the internal pressure was maintained at 8 Kg/cm²G, and polymerization was continued under this condition for four hours. At the end of reaction, methanol was added to decompose the catalyst and atactic polypropylene formed was collected and dried ( yield: 220 g ). The catalyst activity was 30 Kg/gZr•hr and the molecular weight of the polymer obtained was 800.

Comparative Example 5 [ Polymerization ]

A stainless steel autoclave ( capacity: 1.5 liters ), with its internal air thoroughly displaced by nitrogen gas, was charged with 450 ml of pure toluene, 6.3 millimoles of methylaluminoxane ( M.W.: 909; product of Toyo Stauffer Chemical Co. ) and 0.02 millimole of bis(t-butylcyclopentadienyl)zirconium dichloride in that order, and the mixture was heated to 50°C. Propylene was then introduced continuously to the autoclave so that the internal pressure was maintained at 8 Kg/cm²G, and polymerization was continued under this condition for four hours. At the end of reaction, methanol was added to decompose the catalyst and atactic polypropylene formed was collected and dried ( yield: 160 g ). The catalyst activity was 22 Kg/gZr•hr and the molecular weight of the polymer obtained was 500.

Comparative Example 6 [ Polymerization ]

A stainless steel autoclave ( capacity: 1.5 liters ), with its internal air thoroughly displaced by nitrogen gas, was charged with 450 ml of pure toluene, 2.0 millimoles of methylaluminoxane ( M.W.: 909; product of Toyo Stauffer Chemical Co. ) and 0.003 millimole of bis(pentamethylcyclopentadienyl)zirconium dichloride in that order, and the mixture was heated to 50°C. Ethylene was then introduced continuously to the autoclave so that the internal pressure was maintained at 4 Kg/cm²G, and polymerization was continued under this condition for two hours. At the end of reaction, methanol was added to decompose the catalyst and polyethylene formed was collected and dried ( yield: 18 g ). The catalyst activity was 32 Kg/gZr•hr and the molecular weight of the polymer obtained was 70,000.