IL113936A - Catalysts for polymerization and copolymerization of alpha-olefins - Google Patents

Description

1 13936/2 "NOVEL CATALYSTS TO BE USED FOR POLYMERIZATION AND COPOLYMERIZATION OF ALPHA-OLEFINS" 113.936/3 The present invention relates to novel catalysts to be useful in the polymerization and copolymerization of alpha-olefins.

BACKGROUND OF THE INVENTION.

Chirai organometallic complexes became more and more studied and novel compounds are encountered in the last years, being suggested for many purposes. As known, by changing the chirai ligand, the physical properties of the resulting complexes can be adjusted as desired. The design of a chirai metal catalyst is based on the construction of appropriate ligands which create an asymmetric environment around the metal center. According to the U.S. Patent Number 4,356,111 , titanium and zirconium-based compositions are claimed as catalysts for the polymerization of alpha olefins.

According to the Canadian Patent Number 1 ,171,840, an olefin polymerization catalyst is obtained by the reaction of an organo-metallic compound with a titanium compound in the presence of an organo-magnesium compound and HCI.

Certain classes of organo-lanthanide complexes were described in the U.S. Patents Numbers 4,688,773 and 4,801,666, being suggested as catalysts for olefin polymerization.

In the U.S. Patent Number 4,794,096, it is described a catalyst system for the polymerization and copolymerization of olefins, comprising a chirai stereorigid hafnium metallocene in combination with an aluminium compound. It is mentioned that this catalyst system produces useful polymers having molecular weights greater than 10,000 daltons. According to the U.S. Patent Number 4,892,851 , a metatlocene catalyst is suggested for producing syndiotactic polyolefins. It is claimed that this type of catalyst produces a polymer with a novel microstructure.

In the U.S Patent Number 4,975,403 there are claimed catalyst systems which are capable to produce polyolefins which have a broad molecular weight distribution. The catalyst systems comprise at least two different chirai stereo-rigid metallocene and an aluminium compound, preferably an alumoxane. 113,936/3 In a more recent U.S. Patent Number 5,155,890, there are suggested compounds which comprise a cation ligand having cationic metailocene having sterically dissimilar structures, being useful as catalysts for the manufacture of syndiotactic polyolefins.

In the U.S.Patent Number 5,055,438, a polymerization catalyst system is suggested, comprising an alumoxane and a group IV B metailocene having a heteroatom ligand. It is claimed that by using this catalyst system, polymers of high molecular weight are produced.

In the U.S. Patent Number 5,334,677 a coordination catalyst is suggested for obtaining syndiotactic olefins. As mentioned therein, the catalyst contains a bridged metailocene in which one of the cyclopendadienyl rings is substituted in a substantially different manner from the other ring. The metal is selected from one of the group 4b, 5b and 6b from the periodic Table of Elements.

The above review does briefly summarize the large number of patents which describe various types of catalysts, suggested to be used for the polymerization of olefins.

It is an object of the present invention to provide new types of transition metal complexes. A further object of the present invention is to provide improved catalysts for an efficient polymerization of alpha olefins producing stereoregular and atactic polymers and copolymers. It is yet another object of the present invention to provide a catalyst for the polymerization of olefins when used with a cocatalyst which permits a better control on the desired physical properties of the resulting polymer. 113,936/3 BRIEF DESCRIPTION OF THE INVENTION The invention relates to a catalyst useful in the polymerization and copolymerization of alpha-olefins, being represented by the formula: I Ti5-Cp(R') nlBfo5-Cp(R")m]Mto-E(ER*")o}vALp wherein: Cp, is a cydopentadienyl radical, in which each Cp may be unsubstituted or substituted : wherein R' and R" are the same or different radicals selected from the group consisting of C1 to 20 hydrocarbyl radicals or chiral goups.; A, is a metal element selected from the groups 6 to 11 of the Periodic Table; B. is a structural bridging moiety bridging between the two cydopentadienyl groups, and can be a hydrocarbon or a hydrocarbon containing an element from the groups 13, 14, 15 and 16 of the Periodic Table; m = n, a number from 1 to 5; E, is an element selected from the Groups 13,14,15 and 16 of the Periodic Table of elements optionally linked to A ; R"', is an hydrocarbyl group having between 1 to 20 carbon atoms containing a chiral substituent (menthyl, neomenthyl, isomenthyi, phenyl-menthyl, mirtanyl or other chiral hydrocarbyl group containing less than 20 carbon atoms, and , o, is a number: , 2 or 3 depending on the group of E; v, is a number: 1, 2 or 3; Lp, is a donating ligand, selected from a carbonyl, a phosphine group, phosphide and/ or a halide; μ = defines that E is a bridging group between M and A η= defines how many carbons from the Cp are attached to the metal center; M, is a metal selected from the group 3, 4 or 5 of the Periodic Table; When the precatalysts are reacted with methylaluminoxane, novel cationic complexes are produced of the formula described above. These bridged complexes were found to be most suitable as catalytic precursors for the efficient polymerization of alpha olefins after the heterolitycal activation reaction with a strong Lewis acid, such as methylaiuminoxame (MAO), in a suitable solvent producing plausible cationic complexes The term "micro-structure" as appears in Claim 3, is a term well-known in the art. 113,936/3 Figure 1, illustrates schematically a shewing of the catalyst obtained according to the present invention.

A8 the steps of the reactions involved in the preparations of the novel transition metal compounds according to the present invention, were earned out under a rigorous exclusion of oxygen and moisture. For this purpose, there were used either a flamed Schtenk-type glassware in a dual manifold Schtenk tine, or a nitrogen fitted glove-box with a high capacity atmosphere redrculator. The gases used in the polymerization, argon, deuterium, Hhydtogen and the respective olefin (ethytene.propylene) were purified by their passage through a column containing MnO for oxygen removal, followed by a molecular sieve column. The aliphatic hydrocarbon solvents used were dried over a sodium-potassium alloy. The solvents used in the reactions were distilled from under a nitrogen stream and were condensed and stored under vacuum in bulbs, on the vacuum line containing a smafl amount of the indicator Toluene, cydohexane and heptane were also introduced under vacuum and stirred for at least 24 hours, before their use in the catalytic experiments. The respective olefin used, was purified by its stirring over a mixture of sodium-potassium for at toast she hours and was freshty transferred by vacuum. Also, the deutBiated solvents used, were dried over an aloy of sodium-potassium and transferred by vacuum before their use.

According to another embodiment of the present invention, the above novel 113,936/3 early-late bridging complexes were found to be most useful in the polymerization of oJefine and particularly of ethylene and propylene. It was found that these complexes are much more superior catalysts than the known metallocene systems, producing a polymer microstructure of high density polyethylene, as characterized by a 3C nuclear magnetic resonance using a standard analysis.

According to a preferred embodiment, a cocatalyst is also present in these polymerization and copolymerization of the olefins. Preferred cocatalysts are selected from Lewis acids; most preferred Lewis adds are selected from the group of B(C6F5)3 and a!umoxane.

In the following Table , there are presented the activity data for the polymerization of ethylene and propylene, using the following three Bimetallic Early Zirconocene and LateTransition Metal Complexes as catalysts: 1 * (n5-C5H6)2Zr{ -P{SiMe3)2 }2Mo(CO)4. 2 = ^s-C5H5)2Zr^-As(SiMe3)2}2Cr(CO)4, and 3 = ( 5-CsHs)22r{H-P(SiMe3)2}2Ni(CO)4.

The experiments were carried out in a 100 ml flask, interacted with a high vacuum line, using 50 mis of toluene as the reaction solvent. The MAO was prepared by removing the solvent from a 20% (by weight) solution (Schering) at 25°C/10"6 torr. The amounts of catalyst are in μπιοΙ and of the cocatalyst in mmol. The activity is expressed in grams of total polymer per mole of zirconium atmosphere of the olefin per hour. The cocatalyst used in these polymerizations was alumoxane. 113,936/3 TABLE 1: Resutts of Activities of the Catalysts 1 6.38 6.38 25 1:1000 4.70x106 X 1 6.38 6.38 65 1:1000 4.79x10s X 1 6.38 8.62 0 1:1350 2.05x10s X 1 6.38 8.62 25 1 :1350 1.89X106 X 1 6.38 8.62 60 1 :1350 1.23x10e X 1 6.38 17.24 0 1 :2700 4.98x10s X 1 6.38 17.24 25 1 :2700 6.98x10s X 1 6.38 17.24 60 1:2700 6.77x105 X 1 6.38 6.38 25 1:1000 1.2 x10s XX 2 6.03 8.62 25 1:1350 4.68x10s X 2 6.03 8.62 60 1 :1350 5.44x10s X 3 7.24 8.62 25 1:1350 7.46x 05 X x = ethylene xx = propylene 8 - Grams total polymer/mole Zr *atm.ethylene*hour As can be noticed from the above Table, the activity of the catalysts is strongly dependent on the temperature. Thus, by raising the temperature from 0 to 25°C, an increase in the catalytic activity by a factor of about 9 is induced. Also, some effects can be noticed for the ratio of aluminum: zirconium ; thus an increase in this ratio causes only a small decrease in the catalytic activity. Accordingly, the smaller the ratio of MAO to the catalyst used, the better was the catalytic activity. This effect is quite unexpected and even contrary to the results as obtained with the meta!locene early transition metal systems. The molybdenum anionic moiety used in the catalyst complex 1, is more electronegative than the catalyst complex 2, inducing a less tight ton-pair and a more reactive cationic site. On the other hand, the electronic effect of the anionic component in the nickel catalyst complex 3, which is substantially electronegative as the molybdenum catalyst system, although possessing only two carbonyl groups, this effect falls between those of the catalysts complexes 1 and 2. 113,936/3 The infra-red data of the novel complexes are given in the following Table 2.

TABLE 2: Co-Sterchina Bands (cm"1) for the bridged catalyst before and after the addition of the alumoxarte cocatalvst.

Catalyst Before Addition After Addition 1 1942.8 1874.5 1995.1 1909.7 2000.9 2000.4 1852.3 1988.5 (Broad) 1865.9 1882.0 1976.2 1954.3 1943.2 1990.1 1989.7 A general description for a polymerization experiment of an olefin as carried out, in the Examples is given below.

An amount of 6 mg (6.03 X 10-3 mmol) of the catalyst complex 1 and 200 mg of MAO were introduced into a 100 ml flask provided with a magnetic stirrer. The flask was connected to a high vacuum line and an amount of 30 ml of toluene was introduced therein. Ethylene gas, after passing through a gas purification column and temperature equilibration, was introduced into the flask, the gas pressure being continuously maintained at 1 atmosphere with a mercury manometer. After a rapid stirring of the solution, the polymerization was quenched by injecting a mixture of methanol-HC! and the polymeric product was collected by filtration, washed with acetone and pentane and dried under vacuum. 113,936/3 The invention will be hereafter illustrated by the following Examples, being understood that these Examples are presented only for a better understanding of the invention, without imposing any limitation thereto.

EXAMPLE 1. -Synthesis of C 2Z fr-P(Si e3)2hNi(CO)2.

An amount of 0.35 mi (2.71 mmol) was added with a pipette to a solution of 1.57 g, (2.73 mmoi) of C 22r{P(SiMe3)2}2 in 25 ml of toluene at room temperature. Evolution of carbon monoxide was noticed and the colour of the solution changed from deep red to orange, during about 30 minutes. The solution was stirred overnight and then concentrated to its half volume, cooled to 20°C and the product obtained was yellow-orange platelets.

The above desired complex crystallized with one molecule of toluene, in an amount of 1.02 g (yield 48.1%) as a red melt having a melting point of 232°C with decomposition evolving a gas. The infra-red spectrum (KBr) was as follows: 1980 vst, 19338vs, 1610m, br, 1490w, 1432m, 1400w, 1310w, 1248vs, 1050s, br, 1010s, sh, 830vs, 760s, sh, 690m, 680m, 630s. 440m, sh, 398w, 372w, 355w, 335w, br.

The NMR spectrum shows the following: 1H-N (CeDe, 400MHz.o/ppm); 7.00 - 7.14 m (5H, toluene), 5.43 s{10H, Cp), 2.09 s (3H, toluene), O.SOd (36H, SiWtea, 3J{*H31P) 3.8Hz) and, 3 P-N R (CeDe, 161 MHz, o/ppm); -42.ls. The above complex was utilized as a catalyst for ethylene and propylene polymerization at room temperature and at an ambient pressure in order to obtain a high density polyofefin.

EXAMPLE 2.

The procedure as in Example 1 was repeated, using chiral of the C2 and d symmetry type. For the C2 symmetry complex example, the zirconium ethano-bridge indenyl ligand phosphorous bridged nickel complex was used and for the d symmetry complex, the Zr pentamethylcyclopentadienyl silicon dimethyl myrtanylcyclopentadienyl ligand bridged with the phosphorous and the Molybdenum carbonyl complex, was used. In both cases the methanoMnsoluble fraction 113,936/3 ( >90% of the reaction product) was found to be at least 97% isotactic as analysed by means of 13C NMR (pentad analysis) EXAMPLE 3. Polymerization of propylene.

The procedure as in Example 1 was repeated, the resulted complex chiral being used as catalyst for the polymerization of propylene. The methanol-insoluWe fraction (above 90% of the product) was found to be highly crystalline comprising about 97% isotactic polypropylene, as determined by 13C NMR spectroscopy.

EXAMPLE 4. Copolymerization of butane and propylene.

Under rigorously anaerobic conditions, a flask containing 6 mg of the complex: ( 5-C5H5)2Z -P(SiMe3)2{2 i(Co)4 and 1000 equivalents of MAO were dissolved in 50 mis toluene. The vessel was evacuated and filled with a mixture of propylene and butene (50:50). The reaction was carried out at 0°C and at ambient pressure The polymerization started immediately and was monitored manometricaily. At its completion, the polymerization was quenched by the addition of acidified aqueous methanol to afford a random propylene-butylene copolymer.

EXAMPLE 5. Dimerization of iso-butytene.

Under rigorously anaerobic conditions, a flask containing 6 mg of the complex used in Example 3 and 1000 equivalents of MAO were disolved in 50 mis of toluene. The vessel was evacuated and filled with iso-butylene. The polymerization reaction was carried out at ambient temperature and pressure.

The dimerization commenced immediately and was monitored manometricaily. At its completion, the dimerization was quenched by the addition of acidified aqueous methanol yielding the dimer.

EXAMPLE 6. Hydrogenation of propylene.

Under rigorously anaerobic conditions, a flask containing 6 mg of the complex used in Example 3 and 1000 equivalents of MAO were dissolved in 50 mis of toluene. The vessel was evacuated and filled with propylene gas and hydrogen gas in a 1:1 ratio. Hydrogenation commenced immediately and was monitored manometricaily to its completion. 113,936/4 EXAMPLE 7.

The procedure as in Example 3 was repeated using the complex (n5-C6H4R)2Ti(H-B(SiMe3)2{2 o(CO)4{ * (-) neomenthyl), the resutted chiral complex was used as a catalyst for the isotactic polymerization of propylene. The methanoWnsoluble fraction (above 92% of the product) was found to be highly crystalline comprising about 97% isotactic polypropylene, as determined by spectroscopic measurements and melting point.

EXAMPLE 8.

The procedure as in Example 3 was repeated using the complex ( 5-C5H4 )2Ta( -N(Si e3)2{2Mo(CO)4(R= (-) menthyl), the resulted chiral complex was used as a catalyst for the isotactic polymerization of propylene. The methanoWnsoluble fraction (above 90% of the product) was found to be highly crystalline comprising about 95% isotatic polypropylene, as determined by spectroscopic measurements.

EXAMPLE 9.

The procedure as in Example 3 was repeated using the complex ( '-Cs^RkSciu-AsiCMesMN COh (R* (-) neomenthyl), the resulted chiral complex was used as a catalyst for the isotactic polymerization of propylene. The methanoWnsoluble fraction (above 93% of the product) was found to be highly crystalline comprising about 90% isotactic polypropylene, as determined by spectroscopic measurements.

EXAMPLE 10.

E is a fragment bridge which may or not be present. By fragment it should be understood a moiety of Groups 13-14-15 (examples are giving above and below).

Thus, the procedure as in Example 3 was repeated using the complex : (n5- C5H4R)2M(NR2)2(M R = (+) menthyl); wherein, Ms Zr, Ti and Hf.

The resulted chiral complex was used as a catalyst for the isotactic polymerization of propylene. The methanoWnsoluble fraction (above 93, 97, 92% of the product, for M= Zr, Ti, and Hf, respectively) was found to be highly crystalline comprising about 90% isotactic polypropylene, as determined by spectroscopic measurements. 113,936/5

Claims (8)

1. A catalyst useful in the polymerization and copolymerization of alpha-olefins, being represented by the formula: h5-Cp{R,)n]B[ 5"Cp{R)"m]h i-E(ER",)0}vALp wherein; Cp, is a cyclopentadienyl radical, in which each Cp may be unsubstituted or substituted, wherein R' and R" are the same or different radicals selected from the group consisting of C1 to 20 hydrocarbyl radicals or chiral groups; A, is a metal element selected from the groups 6 to 11 of the periodic Table; B, is a structural bridging moiety between the two cyclopentadienyl groups, and can be a hydrocarbon or a hydrocarbon containing an element from the groups 13,14,15 and 16 of the Periodic Table; m = n, being a number from 1 to 5; E, is an element selected from the Groups 13, 14, 15 and 16 of the Periodic Table of elements optionally linked to A; R"\ is an hydrocarbyl group having between 1 to 30 carbon atoms containing a chira! substituent: -chiral substituents are menthyl, neomenthyl, isomenthyl, phenyi-menthyl, mirtanyl or other chiral hydrocarbyl group which contains less than 30 carbons atoms-; o , is a number, 1 , 2, or 3 depending on the group of E; v , is a number, 1, 2 or 3; Lp, is a donating ligand, selected from a carbonyl, a phosphine group, phosphido and or a halide; μ = defines that E is a bridging group between M and A; η = defines the number of carbons from the Cp attached to the metal; and , is a metal selected from the group 3, 4 or 5 of the periodic Table.

2. A polymerization process, in which in the presence of the precatalysts according to Claim 1 and after a heteroiitycal activation reaction with a strong Lewis acid in a suitable solvent, cationic complexes are obtained for the stereoregular polymerization of olefins. 113,963/5

3. The polymerization process according to Claim 2, in the presence of a precatalyst with a co-catalyst, may be used for the polymerization and copolymerization of olefins which are characterized by their micro-structure (isotactic, atactic, syndiotactic, hemiisotactic, or elastomeric).

4. The polymerization process according to Claim 3, wherein said co-catalyst is a Lewis acid.

5. The polymerization process obtained according to Claim 4, wherein said Lewis acid is selected from the group consisting of alumoxane or B(C8 F5)3.

6. The polymerization process according to Claims 3 and 4, wherein the activity of the catalysts is strongly increased by increasing the temperature in the range of between 0 to 250°C.

7. The polymerization process according to Claims 3 to 6, wherein the ratio between the catalyst and said cocatalyst is below 1000 when used for regular copolymerization.

8. A polymerization process according to Claims 2 to 7, substantially as described in the specification and in any one of the Claims 2 to 7.