Bridged metallocene complex for olefin polymerization

Abstract

The invention relates to a metallocene complex according to formula (1) wherein M is a metal selected from lanthanides or transition metals from group 3, 4, 5 or 6 of the Periodic System of the Elements, Q is an anionic ligand to M, k is the number of Q groups and equals the valence of M minus 2, Z.sub.1, Z.sub.2, Z.sub.3 and Z.sub.4 are identical or different and can be chosen from the group consisting of hydrogen and a hydrocarbon radical with 1-20 carbon atoms, and adjacent substituents Z can form a ring system together with the carbon atoms of the Cp ring to which they are bound. ##STR00001##

Claims

1. A composition comprising a metallocene complex according to formula (1): ##STR00009## wherein M is a lanthanide metal or a transition metal of Group 3, 4, 5 or 6 of the Periodic System of the Elements, Q is an anionic ligand to M, k is the number of Q groups and equals the valence of M minus 2, Z.sub.1, Z.sub.2, Z.sub.3 and Z.sub.4 are identical or different and are hydrogen or a hydrocarbon radical with 1-20 carbon atoms, and Z.sub.2 and Z.sub.3 are connected to form a 2-indenyl or 2-tetrahydroindenyl ring system together with the carbon atoms of the Cp ring to which they are bound, wherein the metallocene complex is present on a support.

2. The composition according to claim 1, wherein the metallocene complex is according to formula (1a): ##STR00010## wherein M is a lanthanide metal or a transition metal of Group 3, 4, 5 or 6 of the Periodic System of the Elements; Q is an anionic ligand to M; k is the number of Q groups and equals the valence of M minus 2.

3. The composition according to claim 1, wherein M is Ti, Zr, Hf, V or Sm.

4. The composition according to claim 1, wherein Q is Cl or a methyl group.

5. A process for the preparation of olefin polymers, comprising polymerizing one or more olefins in the presence of the composition of claim 1.

6. The process according to claim 5, wherein at least one olefin is ethylene.

7. The process according to claim 5, wherein an organoaluminum complex is present.

8. The composition according to claim 1, wherein M is Ti, Zr or Hf.

9. The composition according to claim 1, wherein M is Zr.

10. A process for the preparation of olefin polymers, comprising polymerizing one or more olefins in the presence of the composition according to claim 1 and a cocatalyst.

11. The process according to claim 5, wherein at least one olefin is ethylene.

12. The composition according to claim 1, wherein the metallocene complex is according to formula (1a): ##STR00011## wherein M is Ti, Zr, Hf, V or Sm; Q is Cl or a methyl group; k is the number of Q groups and equals the valence of M minus 2.

13. A process for the preparation of olefin polymers, comprising polymerizing one or more olefins in the presence of the composition of claim 12 and a cocatalyst.

14. The process according to claim 13, wherein at least one olefin is ethylene.

15. The process according to claim 13, wherein the cocatalyst is an aluminum-containing cocatalyst.

Description

EXAMPLES

Example 1

Synthesis of 1,8-naphthalene diboronic acid

(1) ##STR00005##

(2) The synthesis of 1,8-naphthalene diboronic acid is shown in scheme 1, above. 1,8-dibromonaphthalene (5 g, 0.0175 moles) was dissolved in diethylether (50 ml) and cooled to −80° C. Butyllithium (2.5M solution in hexane, 21 ml, 0.0525 moles in 50 ml ether) was added dropwise using a dropping funnel. After the addition was completed, the reaction mixture was slowly brought to room temperature. The solution was stirred for 3 hours at room temperature. After this, the reaction mixture was again cooled to −80° C. and trimethyl borate (10 ml, 0.07 moles in 100 ml ether) was added. The reaction mixture was left for stirring at room temperature overnight.

(3) The next day, the reaction was quenched by adding 50 ml of water followed by addition of 100 ml of 2N hydrochloric acid. The mixture was stirred for 45 min and thereafter extracted with ether (3×50 ml). The organic fraction was extracted with 5% sodium hydroxide solution (3×50 ml). The alkaline fraction was acidified with concentrated hydrochloric acid until acidic. A white solid was precipitated. Yield=2.6 g (68%).

Example 2

Synthesis of bis-2-indenyl-1,8-naphthalene

(4) ##STR00006##

(5) The synthesis of the naphthyl ligand is shown in scheme 2. 2-bromoindene (6.66 g, 0.0342 moles) was taken in a round-bottomed flask and dissolved in toluene. Tetrakis triphenyl phosphine palladium (0.054 gm, 8 mol %) was added to the above solution and stirred for 10-15 min. To this solution the diboronic acid from step 1 (3 g, 0.0156 moles) dissolved in ethanol (5 ml) was added, followed by aqueous sodium carbonate (2M, 10 ml). The reaction mixture was heated to 80° C. and stirred for 24 hrs. It was cooled and extracted with dichloromethane (DCM; 5×50 ml). The DCM portion was then extracted with water (2×50 ml), dried over sodium sulfate and concentrated. The crude compound was purified by column chromatography by continuously eluting with hexane as the eluent. Crude yield=3 g; Purified yield=1.6 g (33%)

(6) Alternatively, the below procedure can also be used for the preparation of the ligand precursor.

(7) ##STR00007##

(8) 1,8-dibromonaphthalene (5 g, 0.0175 moles) was taken in a round-bottomed flask and dissolved in toluene. Tetrakis triphenyl phosphine palladium (0.1 gm) was added to the above solution and stirred for 10-15 min. To this solution the 2-indene boronic acid (6.71 g, 0.041 moles) dissolved in ethanol (15 ml) was added, followed by aqueous sodium carbonate (2M, 15 ml). The reaction mixture was heated to 80° C. and stirred for 24 hrs. It was cooled and extracted with dichloromethane (DCM; 5×50 ml). The DCM portion was then extracted with water (2×50 ml), dried over sodium sulfate and concentrated. The crude compound was purified by column chromatography by continuously eluting with hexane as the eluent. Yield=30%.

Example 3

Synthesis of 1,8-naphthalene-bis(2-indenyl)ZrCl2

(9) ##STR00008##

(10) The synthesis of the zirconium complex is shown in scheme 3. The naphthalene ligand was dissolved in tetrahydrofuran (THF, 3.5 g, 0.0098 moles, 70 ml THF). The solution was cooled to −78° C. To the cooled solution butyllithium (BuLi, 7.8 ml (2.5M in hexanes) 0.0196 moles) was added dropwise by using a syringe, very slowly. The solution turned deep red. After the addition of BuLi, stirring was continued for 30 min at −78° C. and then at room temperature for 5 h.

(11) Zirconium chloride (5 gm, 0.0098 moles) was weighed into another round-bottomed flask. The solid was cooled to −78° C. THF (50 ml) and was added dropwise. After the addition, the anion solution was transferred to a dropping funnel fitted to this flask using a cannula. The solution was slowly added to the zirconium chloride solution. After complete addition, the solution was stirred at room temperature overnight and thereafter at 40° C. for 3 h. The solution was then filtered and excess diethyl ether was added. The solution was left in the fridge and filtered cold. The product obtained was recrystallized from toluene. Yield: 1.4 g (28%).

Example 4

Preparing a Metallocene Complex in a Support

(12) The metallocene complex prepared in example 3 was dissolved in toluene and mixed with MAO, 10% in toluene (Al; Zr ratio is 100:1). The solution of the activated catalyst was mixed with 5 g dry silica, Grace 955 (the Zr % is around 0.24). The mixture was dried using vacuum to afford the supported catalyst.

Example 5

Polymerisation

(13) The polymerization experiments were performed by using the polymerization conditions as below. The reactor was a two-liter autoclave vessel, which was heated at 130° C., for 60 minutes under a continuous purge of nitrogen prior to the polymerization reaction. After cooling the autoclave to 85° C., 1 liter of isopentane was introduced into the reactor, and then the reactor was pressurized with 3 bar hydrogen followed by ethylene to pressurize the reactor up to 20 bar. Then 3 ml of triisobutylaluminum (TIBAL)/Amine cocatalyst (1M solution) was injected into the reactor by means of a catalyst injection pump. This was followed by injection of the solid metallocene catalyst (100 mg) in 20 ml of isopentane solvent. The reactor temperature was raised to 88° C. Ethylene polymerization was carried out for 60 minutes; with ethylene supplied continuously to maintain the total reactor pressure at 20 bar. In case a copolymerization experiment is carried out, 100 ml of 1-hexene is introduced into the reactor before pressurizing the reactor with ethylene. In case 1-hexene is used, no hydrogen is fed to the reactor.

(14) Preliminary investigations on the catalytic activity of the supported 1,8-naphthalene-bis(2-indenyl)ZrCl.sub.2 catalyst towards ethylene homopolymerization revealed that the catalyst prepared in example 4 produced 4000 gPE/gCat/h as described in Table 1, which is equivalent to 2.07 kgPE/mmol Zr/h. The activity of the naphthalene catalyst towards ethylene polymerization was found to be almost equal to that of a 2,2′ bis (2-indenyl) biphenyl ZrCl.sub.2 catalyst (4200 gPE/gCat/h) as described in Table 1. It was also observed that the homopolymerization reaction with the naphthalene catalyst was highly exothermic. The catalyst had a high initial activity. This high initial activity makes the catalyst system very suitable for the production of polyethylene in short residence times and smaller polymerization reactors. The activity of the supported catalyst is unexpectedly much higher than the reported activity for the homogeneous catalyst (1 kg PE/mmol Zr/h/bar) as for example described in Angew. Chem. Int. Ed. 2007, 46, 4905-4908.

(15) The catalysts according to the invention are also very suitable for co-polymerization of ethylene with α-olefins. Table 2 describes the ethylene and 1-hexene co-polymerization data. Experiments performed with homogeneous 1,8-naphthalene-bis(2-indenyl)ZrCl.sub.2 and 1,8-naphthalene-bis(2-indenyl)HfCl.sub.2 show improved co-monomer branching per 1000 C atoms of a LLDPE i.e. around 20% to 40% compared to that of 2,2′ bis (2-indenyl) biphenyl ZrCl.sub.2 as summarized in Table 2.

(16) The catalysts according to the invention shows an improved MWD with respect to the 2,2′ bis (2-indenyl) biphenyl ZrCl.sub.2 as summarized in Table 1. The reduction in the density from 0.9398 g/cm.sup.3 produced by 2,2′ bis (2-indenyl) biphenyl ZrCl.sub.2 (WO 2013/091836 and WO 2013/091837) to 0.9314 and 0.9335 g/cm.sup.3 produced by 1,8-naphthalene-bis(2-indenyl)ZrCl.sub.2 and 1,8-naphthalene-bis(2-indenyl)HfCl.sub.2 respectively indicate that the LLDPE produced from the present invention catalysts will improve its mechanical properties for eg. dart impact, puncture resistance. Moreover, the unsupported 1,8-naphthalene-bis(2-indenyl)ZrCl.sub.2 show higher activity compared to that of unsupported 2,2′ bis (2-indenyl) biphenyl ZrCl.sub.2 and 1,8-naphthalene-bis(2-indenyl)ZrCl.sub.2 catalysts.

(17) TABLE-US-00001 TABLE 1 Ethylene homopolymerization for supported 1,8-naphthalene- bis(2-indenyl)ZrCl.sub.2 and 2,2′ bis (2-indenyl) biphenyl ZrCl.sub.2 Cat Activity (kg PE/g cat/hr) 1,8-naphthalene-bis(2-indenyl)ZrCl.sub.2 4.0 (Invention) 2,2′ bis (2-indenyl) biphenyl ZrCl.sub.2 4.2 (Comparison)

(18) TABLE-US-00002 TABLE 2 Ethylene homopolymerization and ethylene-1-hexene copolymerization for unsupported 1,8-naphthalene- bis(2-indenyl)ZrCl.sub.2, 1,8-naphthalene-bis(2-indenyl)HfCl.sub.2 and 2,2′ bis (2-indenyl) biphenyl ZrCl.sub.2 DSC Branch Activity GPC Crystal- per (kg PE/g Mn MW Tm Tc linity 1000 C Density Cat. Cat/hr) (g/mol) (g/mol) MWD (° C.) (° C.) (%) atoms (g/cm.sup.3) 1,8-naphthalene- 86 55000 162800 2.96 132 114 59 14.81 0.9314 bis(2-indenyl)ZrCl.sub.2 (Invention) 1,8-naphthalene- 16.83 94000 292500 3.11 127 — 54 12.49 0.9335 bis(2-indenyl)HfCl.sub.2 (Invention) 2,2′ bis (2-indenyl) 79.92 167500 381000 2.27 131 117 62 10.68 0.9398 biphenyl ZrCl.sub.2 (Comparison)