CA2055220A1

CA2055220A1 - Process for the preparation of an olefin polymer

Info

Publication number: CA2055220A1
Application number: CA002055220A
Authority: CA
Inventors: Andreas Winter; Martin Antberg; Walter Spaleck; Jurgen Rohrmann; Volker Dolle
Original assignee: Individual
Current assignee: Hoechst AG
Priority date: 1990-11-12
Filing date: 1991-11-08
Publication date: 1992-05-13
Also published as: EP0722956B1; DE59109217D1; JP3143174B2; ZA918924B; EP0485820A3; EP0722956A3; EP0722956A2; ES2162953T3; JPH04268308A; AU640288B2; EP0485820A2; DE59108100D1; ES2093058T3; JPH11209420A; AU8776191A; EP0485820B1

Abstract

Abstract of the Disclosure Process for the preparation of an olefin polymer A very active catalyst system for olefin polymerization is composed of an aluminoxane and a metallocene of the formula I

Description

f~
HO~CHST AKTIENGESEL~SCHAFT ~OE 90/F 332 Dr.LO~PP
Description Process for ~he prepaxation of an olefin polymer The inven~ion relates ~o a process for the preparation of olefin polymers having a narrow molecular weight dis-tribution and high isotacticityO

The litaratur~ disclo~es soluble metallocene compounds based on bis(cyclopentadienyl)zirconium alkyl or ha~ide in combination with oli~omeric aluminoxane~ With these systems it is possible to polymerize ethylene and prop-0 ylene with moderate activity, but isotactic polypropylen~
is not obtained. The polypropylenes prepared in this manner are amorphous and therefore have no defined melting point.

Furthermore~ it is known that the catalyst sy~tem ~i -(cyclopentadienyl~tit~niumdiphenyl/methylaluminoxane i~
capable of converting propylene int~ stereo block poly-mers, i.e. polypropylene having longer or shorker iso-tactic sequences (cf. U.S. P~tent 4,522,g82). Substan-tial disadvantages of this catalyst system are the fact that the polymeriza~ion temperatures (0C to -60C) are irrelevant on a large industrial scale, the completely unsatisfactory catalyst activitie~ and the excessively low melting points of the polypropylene products compared with polypropylene prepa.red industrially using heterogeneous catalyst systems based on MgCl2/TiCl4 catalysts.

Isotactic polypropylene can be prepared with the aid o~
ethylenebis(4,5,6,7-te~rahydro-1-indenyl)zirconium dichloride together with an aluminoxane in a suspension polymerization (cf. EP-A 185 918). q'he polymer ha~ a narrow molecular weight distribution, which is advan-tageous for certain applications, for example for high performance injection molding.
' ' . . - . ~

.: .

~ 3 In addition to a number of other deficiencies, such as excessively 1QW metallocene activities or poor product morphology, the melting points of these polypropylenes too are too low, i.e. their crystallinity and hence their 5 hardness are s$ill too low for use of the polymex as a structural material.

A special method for preactivating the metallocene with an aluminoxane was also proposed and leads to a considerable increase in the activity of the catalyst system and to a substantial improvement in the particle morphology of the polymer (cf. DE 37 26 067).

Howeverl a decisive Lmprovement in the mPlting points, crystallinities and hardnesses of the polymers thus prepared cannot be achieved in this marmer.

However, these properties axe very important with regard to the use of polymers as structural materials (for example large hollow articles, pip~9, moldings).
-It is an object to find a proces~ and a catalyst which,having high activi~y, permits the preparation of polymers ha~ing a narrow molecular weight dispersity, high stereo-specificity and a higher melting point and hence hiyher crystallinity and greater hardness.

It has been found that this object can be achieved using bridged metallocene systems substituted in a certain manner in the ligand sphere.

The invention thus relates to a process ~or the prepara-t~on of an olefin polymer by polymeriza~ion or copolymer-ization of an olefin of the ~ormula R~-C~=C~I-*, in which Ra and Rb are identical or different and are a hydrogen atom or a hydrocarbon radical having 1 to 14 carbon atoms, or ~ and Rb, together with the atoms binding them, may form a ring, at a temperature of -60 to 200C, at a pressure of from 0.5 to 100 bar, in solution, in ~, . .

.
: ' . - .

~5' 2'3~

suspension or in the gas phase, in thP presence of a catalyst which is composed of a metallocene as a transition metal compound and an aluminoxan~ of the formula tII) R14 ~ r ~14 l ~ R14 Al ~ t Al - O ~ ~4 (II) for the linear type and/or of the formula III
r Rl~ ~
t Al - ~p~2 (III) for the cyclic type, where, in the formulae (II~ and (III~, the radicals Rl4 may be identical or different and are a Cl-C6-alkyl group, a C8-C,8-aryl group or hydrogen and p is an integer of from ~ to iO, wherein the metallocene is a compound of the formula I

~CR8R9~ "~

2~ M1 ~6 R\7 R4 ~ ~CR R )n ' .

~1~8 in which M1 is a metal of group IVb, Vb or VIb of the Periodic Table, .

Rl and R2 are identical or different and are a hydrogen atom, a Cl-C1O-alkyl yroup, a Cl-C1O-alkoxy group, a C6-C1O-aryl group, a C~-C10-aryloxy group, a C2-C10-alkenyl group, a C7-C40-arylalkyl group, a C7-C40-alkylaryl group, a C8-C40-arylalkenyl group or a halogen atom, R3 and R4 are identical or different and are a hydrogen atom, a halogen atom, a Cl-C10-alkyl group which may be halogena~ed, a C~-C10-aryl group, a -NR2ls, -SRl5, -osiR3l5~ -SiR315 or -PR2l5 radical, in which R15 i~ a halogen atom, a Cl-C1O-al~yl group or a C8-C1O-aryl group, R3 and R6 are identical or different and have the meaning stated for R3 and R4, with the proviso that Rs and R6 are not hydrogen, R7 is Rl~ Rll Rl~ Rll Rll M2 M2 _ M2 _ , - M2 _ (CR2l3) - , - O - M - O
~12 Rl2 R12 ~12 R12 Rll p~
I ~
- C - , - O - M - , R12 ~12 ..
=BR11, =Al~ Ge-, -Sn-, -O-, -S-, =SO, =SO2l =NR11, =CO, =PRl1 or =P(O)R
where R11, R12 and Rl3 are identical or different and are a hydrG-gen atom, a halogen atom, a Cl-C1O-alkyl ~roup, a C1-C10-fluoroalkyl group, a C6-C1O-aryl group, a C6-C1O-fluoroaryl group, a Cl-C1O-alkoxy group, a C2-C1O-alkenyl group, a C7-C40-arylalkyl group, a Ca-C40-arylalkenyl group or a C7-C40-alkylaryl group, or R11 and R1Z or Rl1 and R13, together with the atom~
binding them, each form a ring, ~2 iS siLicon, germanium or tin, R8 and R9 are identical or different and have the meaning stated ~or Rl1, m and n are identical or different and are zero, 1 or 2, m plu8 n being zero, 1 or 2, and - :; , ~ ~ : .. :

~ ~ o~

the radicals Rl are identical or different and have the meaning stated for R1l, R12 and R13.

Alkyl is straight-chain or branched alkyl. Halogen (halogenated) is fluorine, chlorine, bromine or iodine, pre~erably fluoxine or chlorine.

The present invention furthermore relatPs to the poly-ole~ins prepared by the process described.

The catalyst to be used for the prooess according to the invention is composed of an aluminoxane and a metallooene of the formula I

~R ~8 :

~CR~R9)~

R2~ Ml R6 ~7 R4 ~ (CR8R9~n `~
/~ :

l~l)8 In the formula I, M1 is a metal of group IVb, Vb or VIb of the Periodic Table, for e~ample titani~m, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum and tung~ten, preferably zirconium, ha~nium and titanlum.

R1 and R2 are identical or different and are a hydrogen atom, Cl-C1O-alkyl group, preferably a C~-C3-alkyl group, a Cl-C1O-alkoxy group, preferably a Cl-C3-alkoxy group, a C6-C10-aryl group, preferably a C6~C8-aryl group, a C6-C10-aryloxy group, preferably a C6-C8-aryloxy g:roup, . . -.

~. i 3 c~ ~? ~ 2 ~

a C2-C10-alkenyl group, preferably a C2-C4-alkenyl group, a C7-C40-arylalkyl group, preferably a C7-Cl~-arylalkyl group, a C7-C40-alkylaryl group, preferably a C7 C12-alkylaryl group, a C8-C40-arylalkenyl group, preferably a C8-Cl2-arylalkenyl group, or a halogen a~om, preferably chlorine.

R3 and R4 are identical or different and are a hydrogen atom, a halogen atom, preferably a fluorine, chlorin~ or bromine atom, a Cl-C1O-alkvl group, preferably a C1~C4-alkyl group, which may be halogenated, a C6-C1O-aryl group, preferably a C6-C8-aryl groupV a -NR2l5, -SRl5, -oSiR315, -SiR3l5 or -PR215 radical, wherein Rl5 is a halogPn atom, preferably a chlorine atom, or a Cl-C10-alkyl group, preferably a Cl-C3-alkyl group/ or a C6-C10-aryl group, preferably a C6-C~-aryl group. R3 and R4 are particularly preferably hydrogen.

R5 and R6 are identical or diffexent, pre~erably :Ldenti-cal, and have the meanings described for R3 and R4, with th~ proviso that R5 and R6 m~y n~ be hydrogen. R5 and R6 are preferably (Cl-C4)-alkyl which may be halogenated, such as methyl, ethyl, propyl, i~opropyl, butyl, isobutyl or trifluoromethyl, in particular methyl.

R7 is Rll Rll Rll Rll Rll _ ~2 __ M2 _ ~2 _ _ ~2 _ ~CR~3) - , 0 - M2 _ 0 _ Rll Rll - C - , - O - M2 _ R12 ~12 ~BR~ AlRl1, Ge-, -Sn-, -Q-l -S-, =S0, =S02, =NR , -C0, =PR1l or =P(O)Rll, in which Rll, Rl2 and Rl3 are identical or different and are a hydrogen atom, a halogen atom, a Cl-C1O-alkyl group, preferably a Cl-C4-alkyl group, in par-ticular a methyl group, a Cl-C10-fluoroalkyl group, preferably a CF3 group, a C6-C1~-aryl group, preferably a ,. . .

':

2 ~ æi ~ V

C6-Ca-aryl group, a C6-C10-fluoroaryl group, preferably a pentafluorophenyl group, a Cl-C10-alkoxy group, preferably a C1-C4-alkoxy group, in particular a methoxy group, a C2-C10-alkenyl group, preferably a C2-C4-alkenyl group~ a S C7-C40-arylalkyl gro-lp, preferably a C7-C10-arylalkyl group, a C8-C40-arylalkenyl group, preferably a C8 C12-arylalkenyl group, or a C7-C40-alkylaryl group, preferably a C7-Cl2 alkylaryl group, or R11 and R12 or R11 and R13, together with the atoms binding them, each form a ring.

M~ is silicon, germanium or tin, preferably silicon or germanium.

R is preferably =CR1lR12, =siR11R12 =GeR11R12 O
=SO, =PR1l or -P(O)R11.

R3 and R~ are identical or different and have the meanlngs stated for R11.

m and n are identical or different and are zerol 1 or 2, preferably ~ero or 1, m plu8 n being zero, l or 2, preferably zero or l.

The radicals R10 are identical or different and have the meanings stated for R11/ R12 and Rl3. ~he radicals R10 are preferably hydrogen atoms or a Cl-C1O-alkyl group, prefer-ably a C1-C4-alkyl group.

~hus, the particularly pxeferred metallocenes are the compounds of the formulae A, B, and C

R~R9C ~ (~
R~2~ 12~5 ., .. ,. , . :

-.

~' ~

1 2,--,c h~ ~ R ( C ) \ ~ 6 in which Ml is Zr or Hf, R1 and R2 are methyl or chlorine, R~ and R6 are me~hyl, ethyl or trifluoromethyl and R8, R9J R11 and R12 have the abovementioned meanings, in particular the 5 compoun~s I mentioned in the Illustrative ~xamples~

The chiral metallocenes a7~e U5ed as a racemate for the preparation of highly i80tactic pvly-1-olefins. Howe~er, it iS al80 possible to u~e the pure R or S foxm. An optically active polymer can be prepared with these pure stereoisomeric forms. However, the meso ~orm of the metallocenes should be isolatad since the cent~r (the metal atom) which is active with regard to polymerization in these compounds is no longer chiral owing to mirror symmetry at the central metal and therefore cannot lS : produce a highly isotactic polymer.

The separation of the stereoisomers is known in principle.

The metallocenes de~cribed above can be prepared, for example, according to the ~ollowing re~ction sc.heme:

H2RC ~ ButylLi ~ RCLi X (CR8R9~ -R7-(CR8R9) -X
H2R ~ ButylLi - ~ HRdLi ~ ~~~ L--------~

HRC-(CR8R9~m-R7-(CR8R9)n-RdH 2 8uty~

~iRC- (CR8R9)m-R7- (CR8R9)n-RdLi Mli_14 (R8R9C~m _ RC ~R~R9C)m _ RC
7 ~ ` RlLi ~7 '1~
Cl `~ C1 R8R9C ) n _ Rd ~ R8R9C ) n _ Rd (additional hydrogenation step if N2R and and H2Rd are used as starting compounds) (R8R9C)m _ Rc Rl ~
R2Li R7 Ml~
R2 ;
(R8R9C)n ~ Rd X = Cl, Br, I or O-tosyl;

. . ~ . , ;: , .

10 ~ r~

}I RC ' = ~ H2RC = yJ~

(~ ~4 ~ )8 H2R = ~ 6 ~2R ~ 6 The preparation proce~se are known from the liter~ture;
cf. Journal of Organometallic Chem. ~88 (1985) 63-67, EP-A 320 762 and the Illustrative Examples.

According to the invention, the cocatalyst usad i5 an alumino~ane of the formula (II) Al - O ~ O ~ Al (II) for the li~ear type and/or of the formula ~III) ~ R1~ 1 (III) t - Al ~ p-~2 for the cyclic type, where, in the formulae (I~) and (III), the radicals R14 may be identical or different and are a Cl-C6-alkyl group, a C6-Cl~-aryl group or hydrogen and p is an integer from 2 to 50, preferably from 10 to 35.

Preferably, the radicals R14 are identical and are methyl, : 15 isobutyl, phe~yl or benzyl, particularly preferably methyl.

If the radicals R14 are di~ferent, they ara preferably methyl and hydrogen or alternatively methyl and isobutyl, hydrogen or isobutyI preferably being pre~ent in an amount of 0.01-40% (number of radicals R14).

'rhe aluminoxane can be prepared in Yarious ways by known -, h ~ 2 ~

processes. One of the methods, for example, is to react an aluminum-hydrocarbon compound and/or a hydridoaluminum-hydrocarbon compound wi~h water (gaseous, solid, liquid or bound - for example as water of crystal-lization) in an inert solvent (such as, for example,toluene). For the preparation of an aluminoxane having different alkyl groups Rl4, ~wo different aluminumtri-alkyls (AlR3 + AlR'3), according to the desired composi-tion, are reacted with water (cf. S. Pasynkiewicz, Polyhedron 9 (1990) 429 and EP-A 302 424).

The exact structure of the aluminoxanes II and III is not known.

Regardless of the method of preparation, the common feature of all aluminoxane solutions is a changing content of unconverted aluminum starting compound, which is pres~nt in free form or as adduct.

It is possible to preactivate the metallocene with an aluminoxane of the formula (II) and/or (III) prior to use in the polymeriza~ion reaction. This substantially increases the polymerization activity and improves the particle morphology.

The preactivation o~ the transîtion metal compound is carried out in solution. The metallocene is preferably dissolved in a solution of the aluminoxane in an inert hydrocarbon. A suitabIe inert hydrocarbon i~ an aliphat-ic or aromatic hydrocarbon. Toluene is pr~ferably used.

The concsntration of the aluminoxane in the solution i~
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 solution. The metallocene can be used in the same concentration, but it is preferably employed in an ~mount o~ 10 4 - 1 mol per mole o~ aluminoxane. The preactivation time is 5 minutes to 60 hours, preferably from 5 to 60 minutes. A temperature of -784C to 100C, - : :
: : : , ':
:~ : - , - ,, preferably 0 to 70C, is employed.

The metallocene can also be prepol~merized or applied to a carrier. The olefin used in the polymeri~ation, or one of the olefins used in the polymerization, is preferably employed for the prepolymerization.

Suitable carriers are, for example~ ~ilica gels~
aluminas, solid aluminoxane or other inorganic carriers.
Another suitable carrier is a polyolefin powder in finely divided form.

In a further possible embodLment of the process according to the invention, a salt-like compound of the fonmula RXNH4_XBR r 4 or of the ~ormula R3PHBR~ 4 iS used as the cocatalyst instead of or in addition ~o an aluminoxane.
In the formulae, x is 1, 2 or 3, the radicals R are identical or different and are a].kyl ox aryl and R' is aryl which may also be fluorinated or partially fluorina-ted. In this ca~e, the catalyst is composed of the reaction product of a metallocene with one of the stated compounds ~cf. EP-A 277 004 and the Preparation Examples E and F). To remove catalyst poisons pre~ent in the propylene, purification with an aluminumalkyl/ for e~ample AlMe3 or AlEt3,-is advantageous. This purifica-tion can be carried out in the polymerization system itself, or the propylene is brought into contact with the Al compound before being added to the polymerization system and is then separated off again.

The polymerization or copolymerization i8 carried out in a known manner in solution, in su~pension or in the gas phase, continuously or batchwise, in one or more ~tages at a temperature of -60 to 200DC, preferably 30 to 80C.
Olefins of the formula R~-CH=CH-Rb are polymerized or copolymerized. In this formula, R~ and * are identical or different and are a hydrogen atom or an alkyl radical having 1 to 14 carbon atoms.

-`

. .
"., ~ 13 ~ iJ
However, R~ and Rbt together with the carbon a~oms binding them, may also form a ring. Exampleq of such olefins are ethylene, propylene, l~butene, 1-hexene, 4-methyl-1-pentene, 1 octene, norbornene or norbornadiene. In particular, propylene and e~hylene are polymerized.

If required, hydrogen is added as a molecular weight regulator. The total pressure in the pol~merization system i5 0.5 to 100 bar. Polymerization in the in-dustrially particularly interesting pressure range of from 5 to 64 bar is preferred.

The metallocene is used in a concentration~ based on the transition metal, of 10-3 to 10-8" preferably 10-4 to 10-7, mol of transition metal per dm3 of solvent or per dm3 of reactor volume. The al~minoxane is used in a concentra-tion of 10-5 to 10~1 mol, preferably 10-4 to 10-2 mol, per dm3 of solvent or per dm3 of reactor volume. In prin-ciple, however/ higher concentrations are also possible.

If the polymerization is carried out as a suspension or solution polymerization, an inert solvent usually used 20 for the Ziegler low pressure process is employed. For example~ the reaction is carried out in an aliphatic or cycloaliphatic hydrocarbon; for example, butane, pentane, hexane, heptane, isooctane, cyclohexane and methylcyclo~
hexane may be mentioned as examples of such hydrocarbons.

A gasoline fraction or hydrogenated diesel oil fraction may also be used. Toluene is also suitable. Polymeriza-tion is preferably carried out in the liquid monomer.

If inert solvents are used, the monomers are metered in as a gas or liquid.

The polymerization can be carried out for any desired time, since the catalyst system to be used according to the invention shows only a slight tLme-dependent decrease of polymerization activity.

;
: . . .

,: :- : -~ :
: : ~: :
' ~J ~

The process according to the invention i~ distinguished by the fact that, in the indu~trially interesting temp-exature range between 30 and 80C, the metallocenes according to th~ invPntion produce polymers having a high molecular weight, high stereospecificity, a naxrow molecular weight di~persity and in particular a high melting point, and hence high crystallinity and great hardness.

The Examples which follow are intended to illustrate the 10 invention in more detail.

VN is the viscosity number in cm3/g M~ is the weight average molecular 1 Determined by weight ~ gel permeation M~M~ is the molecular weight ; ohromatography 15 dispersity II is the isotactic index (II = mm+l/2 mx), determined by l3C-N ~ spectroscQpy niSo is the length of the isotactic blocks (in prop~lene unit~) (n160 = 1 + 2 mm~mr)~ d~termined by l3C-NMR
20 spectroscopy Melting points and hea~s of fusion ~H~p were determined by DSC (20C/min heating/cooling rate).

The melt flow index (MFIl 230C, S kg load) was measured according to DIN 53,735 and expressed in g/10 min, 25 Synthesis of the metallocenes used in the Examples:

The preparation of the chelate ligands ~i~o-(CRBR9)~-R7-(CR~R9)n-RdLi by deprotonation is known and is carried out according to:
J. Am. Chem. Soc., 112 (lY90) 2030-2031, ibid. 110 (1988) 30 6255--6256, ibid. 109 (1987), 6544-6545, J. Organomet.
Chem., 322 ~1987) 65-70, New. J. Chem. 14 (1990j 499-503, Bull. Soc. Chim.~ 1967, ~954.

- 15 ~ 2 2 ~
The starting indenyl compounds H2R~ and H2Rd or H2RC and H2Rd are prepared sLmilarl~ to or by means of known synthesis method~
J. Org. Chem., 49 (1984), 4226-4237, J. Chem. Soc., Perkin II, 19811 403-408, J. Am. Chem. Soc., 106 (1984) 6702, J. Am~ Chem. Soc., 65 (1943) 567, J. Med. Chem.~ 30 (1987) 1303-1308, Chem. Ber. 85 (1952) 78-85 and the Illustrative Examples.

Synthesis of the starting substances I) Synthesis of 2-Me-indene 110.45 g ~0.836 mol) of 2-indanone were dissolved in 500 ml o diethyl ether, and 290 cm3 of 3 N (0.87 mol) of ethereal methyl-Grignard solution wexe added dropwise in such a way that gentle refluxing occurred. After boiling for 2 hours with gentle refluxing, the mixture was added to an ice/hydrochloric acid mixture and adju~ted to a pH
of 2-3 with ammonium chloride. The organic phase was separated off, washed with NaHCO3 and sodium chloride solution and dried. 98 g of crud~ product (2-hydroxy-2-methylindane) were obtained, which was not further purified.

This product was dissolved in 500 cm3 of toluene and the solution was heated with 3 g of p-toluenesulfonic acid .~ under a water ~eparator until elimination of water had ended, the mixture was evaporated down, the residue was taken up in dichloromethane and the solution was ~iltered over silica gel and the filtrate distilled in vacuo (80C/10 mbar).
Yield: 28.49 g ~0.22 mol-26%).

The synthesis of this compound is also described in:
C.F. Koelsch, P.R. Johnsonl J. Am. Ch0m. Soc., 65 (1943) 5~7-573.

.

~ ~ -.

~ 16 ~ '3'~
II) Synthesis of (2-Me-indene)2SiMe2 13 g (100 mmol) of 2-Me-indene were dissolved in 400 cm3 of diethyl ether, 62.5 cm3 of 1.6 ~ ~100 mmol) n-butyl-lithium/n-hexane solution were added dropwi~e in ~hs course of 1 hour, while cooling with ice, and stirring was then continued for 1 hour at ~35C.

6.1 cm3 (50 mmol) of dLmethyldichlorosilane in 50 cm3 of Et20 were initially taken, the lithio salt solution was added dropwise at 0C in the course of 5 hours and the mixture was stirred overnight at room temperature and allowed to stand over the weekend.

The solid which had settled out was filt~red off and the filtrate was evaporated to dryness. After extraction with small portions of n-hexane/ filtration was carrled out and the filtrate evaporated down. 5.7 g (18.00 mmol) of white crystals were obtained. The mother li~uor was evaporated down and then purified by column chromatog-raphy (n-hexane/H2CCl2 9 : 1 parts by volume), 2.5 g (7.9 mmol-52%) of product being obtained (as an isomer mixture).

rF (SiO~; n~hexane/H2CCl2 9 : 1 parts by volume) = 0.37 ~he lH-NMR spectrum shows the signals to be expected ~or an isomer mixture, in shift and integration ratio.

III) Synthesis of (2-Me-ind)2CH2CH2 3 g (23 mmol) of 2-Me-indene were dissolved in 50 cm3 of THF, 14.4 cm3 of 1.6 N (23.04 mmol) n-butyllithium/n-hexane solution wera added dropwise and stirring was then carriedout for lhour at65C. Thereafter~ 1 cm3 ( 1 1 ~ 5 mmol) of 1,2-dibromoethane was added at -78C and the mixture was allowed to warm up to room temperature and stirred for 5 hour~. After being evaporated down, the mixture was purified by column chromatography (SiO~;

.
- ~ . . : .

- 17 ~ 2 n-hexane/H2CCl2 9 : 1 parts by volume).

The product-containing fractions were combined and evaporated down, the residue was taken up in dry ether, the solution was dried over MgS04 and filtered and the solvent was stripped off.

Yield~ 1.6 g (5.59 mmol-49%) of an isomer mixture rF ~SiO2; n-hexane/H2CCl2 9 : 1 parts by volume) = 0.46 The lH-NMR spectrum meets the expectation for an isomer mix~ure in signal shift and integration.

A) Synthesis of rac-dLmethylsilyl(2 Me-4/5,6,7-tetra-hydr~ indenyl)zzirconium dichloride a. Synthesis of the precursor rac-dLmethylsilyl(2-Me-1-indenyl)2zirconium dichloride 1.~8 g (5.31 mmol) of the chelate ligand dLmethylsilyl(2-methylindene)a were added to 50 cm3 o THF, and 663 cm3 o~ a 1,6 N (10.61 mmol) n-Bu~i/n-hexa~e solu~ion were added d.ropwise. The addition was carriQd out at ambient temperature in the course of 0.5 hour. Stirring was carriad out ~or 2 hours at about 35C, after which the solvent was stripped off in vacuo and the residue was stirred with n pentane, filtered off and dried.

The dilithio salt thus obtained was added to a su~pension of 1.24 g t5.32 mmol) of ~rC14 in 50 cm3 of CH2Cl2 and the mi~ture was stirred ~or 3 hours at this temperature.
After warming up to room temperature overnight, the mixture was evaporated down. The lH-NMR spectrum indi-cated a rac/meso mixture in addition to th0 presence of a littIe ZrCl4(thf)2. After stirring with n-pentane and drying, the solid, yellow residue was suspended in THF, filtered off and investigated by NMR spectroscopy. ~hese three operations were repea~.ed several ~imes, finally, O.35 g (O.73 mmol-14%) of the product was obtained in .

which, according to lH-NMR, the rac form was concentrated to more than 17 : 1.

The compound gave a correct elemental analysis and the following NMR signals (CDC13, 100 MH2): ~ = 1.25 (s, 6H, Si-Me); 2.18 (s, 6H, 2-Me), 6.8 ts, 2H, 3-H Ind); 6.~2-7.75 (m, 8H, 4-7-H-Ind).

b. Synthesis of the end product 0.56 g ~1.17 mmol) of the precursor rac-dimethylsilyl(2-Me-l~indenyl)2zirconium dichloride was di.ssolved in 70 cm3 of CH2Cl2 and the solution was introducedr together with 40 mg of PtO2, into a 200 cm3 NOVA ~tirred autoclave.
Stirring was then carried out for 4 hours at room temp-erature under an H2 pressure of 40 bar. The filtrate was evaporated down, leached with toluene/n-hexane (1 2 parts by volume) and filtered, and the filtrate was evaporated down. After the addition of n-pentalle, the resulting suspension was filtered and the residue dried.
~he yield was 0-34 g tO.7 mmol-60~6). The lH-NMR spectrum (CD2Cl2, 100 MHz) gave the following signals: ~ = 0.90 (s, 6H, Me-Si~; 1.43-1.93 (m, 8H, indenyl-H); 2.10 (s, 6H, 2-Me); 2.~4-3.37 (m, 8H, indenyl-H); b.05 (s, 2H, 3-H-Ind) .

B) Synthe~is of rac -ethylene~2-Me-4,5,6,7-tetrahydro-1-indenyl)2zirconium dichloride a. Synthesis of the precursor rac-ethylene ( 2-Me 1-indenyl)2zirconium dichloride 14.2 cm3 of 2.5 N (35.4 mmol) n-Bu~i/n-hexane solution were added dropwise to 5 . 07 g ( 17.7 mmol) of the ligand ethylene(2-methylindene)2 in 200 cm3 o~ THF at room temperature in the course of 1 hour and stirring was ~hen carried out for 3 hours at about 50C. A precipitate which is ~ormed in the meantime goes into solution again.
The mixture was allowed to s tand ovexnight.

- 19 ~
6.68 g (17.7 mmol) of ZrCl2(thf)2 in 250 cm3 of THF were added dropwise, simultaneously with the above dilithio salt solution, to about 50 cm3 of T~F at 50C, and the mixture was then stirred for 20 hours at this temperatura. The toluene extract of the evaporation residue was e~aporated down. After ex~raction of the residue with a little THE, recrystallization was effected from toluene. 0.44 g (0.99 mmol-5.6%) of product was obtained, the rac ~orm being concentrated to more than 15 : 1.

The compound gave a correct elemental analysis and the following NMR signals (CDC13, 100 M~z): ~ = 2.08 (2s, 6H, 2-Me); 3.45-4.18 ~m, 4H, -CH2CHz-), 6.65 ~2H, 3-H-Ind); 7.05-7.85 (m, BH, 4-7-H-Ind).

b. Synthesis of the end product 0.56 g (1.25 mmol) of rac-ethylene(2--Me-l-indenyl)2-zirconium dichloride wa~ dis~olved in 50 cm3 of C~2C12 and the solution was introduced, together with 40 mg of PtOz, into a 200 cm3 ~OVA stirred autoclave. Stirring was then carried out ~or 2 hours at room temperature under an H2 pressure of 40 bar. The mi~ture was evaporated to dryness and the residue was sublimed in a high vacuum at a bath temperature of about 100C. 0.46 g (1.01 mmoi~81%) of product was obtained. ~he elemental analysis was correct and the lH-NMR spectrum shows the following signals: ~ = 1.46-1.92 (m, BH, Indenyl-H), 2.14 (s, 6H, 2-Me); 2.49-~.73 (m, 6H, Indenyl-H and -CH2C~2~), 2.B9-3.49 (m, 6H, Indenyl-H); 6.06 ~s, 2H, 3-H-Ind).

C) Synthe~i~ of rac-dimethylsilyl(2-Me-4,5,6 r 7~
tetrahydro l-indenyl)2zirconiumdimethyl O . 2 7 g (O.56 mmol~ of rac-dimethylsilyl(2-Me-4,5,6,7-tetrahydro-1-indenyl)2zirconium dichloride was dissolved in 20 cm3 of Et2O, the solution was cooled to -50C and 1.1 cm3 of P 1.6 N (1.76 mmol) ethereal Me~i solution were .
,..... : ~ .

2~3~2~
~o --added dropwise. Stirring was then carried out for 1 hour a~ 0C and, after the sol~ent had been e~changed for n-pentane, stirring was carried out for 0.5 hour at room temperature. The filtered evaporation residue was sublimed in a high vacuum. 0.21 g (0.47 mmol-83~) of a product which gave a correc~ elemental analysis was obtained .

D) 5ynthesis o rac-ethylQne(2-Me-4,5,6,7-tetrahydro-1-indenyl)2zirconiumdimethyl 0.18 g ~0.40 mmol) of rac-e~hylene~2-Me-4,5,6~7-tetra-hydro-l-indenyl)2zirconium dichloride are di~solved in 20 cm3 of Et2O, the solution was cooled to -50C and 1 cm3 of a 1.6 N (1.6 Immol) ethereal MeLi solution is added dropwise~ The mixture was stirred for two hours at 0C, and after the solvent had been exchanged for n-hexane stirring was carried out for 0O5 hour at ~mbient tempera-ture. Filtration and evaporation were followed by sub-limation. 0.13 g (0.31 mmol-79~) of product giving~the correct elemental analysis was obtained.

E~ Reaction of rac-dimethylsilyl(2-Me-4,5,6,7-tetra~
hydro-1-indenyl)22irconiumdimethyl with [ Me2NHP~, ~ B ( C6F5 ) 4 ]

O.15 g (O.33 mmolj of rac-dimethylsilyl~2-~e-4,5,6,7-tetrahydro-l-indenyl)2zirconiumdimethyl was addad to 0.25 g (0.31 mmol) of [Me2NHPh][B(C~F5)4] in 30 cm3 of toluene. After being stirred for one hour at room temperature, the solution, which was then- intensely colored, was evaporated down and the re idue wa~
extracted with a small amount of n-pentane and then dried in vacuo.

An aliquot part of the reaction mixture was used for the polymerization.

`

, :

~ 3 F) Reaction of rac-ethylene(2-Me-4,5,6,7-tetrahydro-1-indenyl)2zirconiumdimethyl wi.th ~Bu3NHI[B(C6Hs~]

O.12 g (O.23 mmol) of rac-ethylene~2-Me-4,5,6,7-tetra~
hydro-1-indenyl)2~irconiumdimethyl was added to 0.14 g (0.~8 mmol) of [Bu3NH][BtCfiH5)4] in 20 cm3 of toluene.
Stirring was carried out for l.S hours at xoom ~empera-ture, and the now deeply colored reaction mixture was evaporated down and extracted with n-pentane, and the slightly oily residue wa~ dried.

An aliquot part of the reaction mixture was used for the polymerization.

Example 1 A dry 24 dm3 reactor was flushed with nitrogen and filled with 12 dm3 0~ uid propylene.

35 cm3 of a solution of mekhylaluminoxane in toluene (corresponding to 52 mmol of Al, maan degree of oligomer-ization n = 17) were then added, and the batch was stir-xed for 15 minutes at 30C. At the same time, 5.3 mg (0.011 mmol~ of rac-dimethylsilyl(2-Me-4,5,6,7-tetra-hydro-l-indenyl)2zirconium dichloride were dissolved in 13.5 cm3 of a solution of methylsluminoxane in toluene (20 mmol of Al) and were preactivated by allowing the solution to stand for lS minutes. The solution was then introduced into the reactor and the polymerization system was brought to 70C (in the course of 5 minute~ by heating and wa~ kept at this temperature for 3 hours by cooling. The activity o~ the metallocene was 50.3 kg of PP per g of metallocene per h.

VN = 37 cm3/g; N~ = 24,300 g/mol; M~/M~ = 2.4; II = 96.0%;
n~O = 62; m.p. = 150C ~H~,p = 104 J/g.

:

.
, , ~ .

:' ::

c~

Example 2 Example 1 was repeated, except that 19.5 mg ~O.04 mmol) of the metallocene were used and the pol~merization temperature was 50C. The activity of the metallocene was 18.8 kg of PP per g oF ~etallocane per h.

VN = 72 cm3/g; M~ = 64,750 gJmol; N~/N~ = 2.1; II = g6.0%;
nl90 = 64; m.p. = 154C; QHmp = 109.5 J/g.

Example 3 Example 1 was repeated, except ~hat 58.0 my (0.12 mmol) of the metallocene were used and the polymerization temperature was 30C. The ac~ivity of the metallocene was 9.7 kg of PP per g of metallocene per h.

VN - 152 cm3~g; M~ = 171,000 g/mol; M~/M~ = 2.~; IX =
99.9~; ni~O = > 500; m.p. - 160C; QH~p = 103 J~g.

Comparative Examples A - H

Examples 1 ~o 3 were repeated, except that the the metallocenes dimethylsilyl(2-Me-1-indenyl)2zirconium dichloride ~metallocene 1), dimethylsilyl(4,5,6,7-tetra-hydro-l-indenyl)2zirconium dichloride (metallocene 2) and ~ .
d~nethylsilyl~l-indenyl~2zirconium dichloride (metallocene 3) were used.

Comparative Metallo- Polym. temp. ni30 m.p. ~H~p.
Example cene tC] [~C] tJ/g~
A 1 70 38 145 86.6 B 1 50 48 148 88.1 C 1 30 48 152 90.2 G 3 50 ~4 142 ' ~?

Comparison of the Comparative Examples FJG with D/E
demonstrates the positive effect of the 4,5,6,7-tetra-hydroindenyl ligand compared with indenyl, and Compara-tive Examples F/G/H compared with ~/B/C show the positive effect of substitution in the 2-position of the indenyl ligand.

However, comparison with Examples 1 to 3 shows that only the combination of substitution in the 2-po.sition with the tetrahydroindPnyl system leads to very high melting points and heats o~ fu~ion and hence to high crystal-linity and hardness o the polymers.

Example 4 --Example 1 was repeated, except that 6.8 mg (0.015 mmol) of ethylene(2-Me-4,5,6,7-tetrahydro-1-indenyl)zzircollium dichloride were u~ed.

~he metalloc0ne activity was 72.5 kg o~ PP per g of metallocene per h.

VN = 35 cm3/g; M~ = 20,750 g~mol; M~/M~ = 1.9; II = 94.5%;
nl~O = 34; m.p. = 141C; ~H~p = 92.4 J/g.

Example 5 .

Example 4 was repeated, except that 2a.1 mg ~0.062 mmol~
of the metallocsne were used and the polymerization temperature was 50C. Themetallocene activity was 28.5 kg of PP per g of metallocene per h.

VN = 51 cm3~g; N~ = 28,200 g/mol; N~/N~ - 2.2; II = 94.8%;
nl30 o 35; m.p. = 143C; ~H~.p a 97.9 J/g~

Example 6 Example 4 was repeated, except that 50 mg (0.110 mmol) of the metallocene were used and the polymerization ~3~5~2~
- ~4 -temperature was 30C. The metallocene activity was 10.9 kg of PP per g of metallocene per h.

VN = 92 cm3/~; M~ - 93,800 g/mol; M~/M~ = 2.2; II - 95.5%;
n1sO = 48; m.p. = 151C, ~Hmp = 99 J/g Comparative Examples I - O

Examples 4 to 6 were repeated, but the me~allocenes u~ed wereethylene(l-indenyl)2zirconiumdichloride(metallocene 4) and ethylene(2-Me-1-indenyl)zzirconium dichloride (metallocene 5).

10Comparative Metallo- Polym. temp. n~8~ m.pO ~H~p Example cene [CJ [C] [3~g]
I 4 70 23 132 64.9 K 4 50 30 138 78.1 L 4 30 29 137 78.6 M 5 70 25 134 77.0 N 5 50 30 138 78.9 0 5 30 32 13B 78.6 Comparison of Comparative Examples I to O with Examples 4 to ~ demonstrat~s the effect of substitution in the 2-position in con~unction with the u~e of the tetrahydro-indenyl system. ni~O, the melting point snd the heat of fusion are each substantially higher in Examples 4-6 -thus, the crystallinity and the hardness of the polymers are also substantially .improved.

Example 7 Example 2 was repeated, except that 15.0 mg (O.034 mmol~
of rac-dimethylsilyl~2-Me-4,5,6,7-tetrahydro~
indenyl)2æirconiumdimethyl were used as the metallocene.
The activity of the metallocene was 21.9 kg of PP per g of metallocene per h~

V~ = 75 cm3~g; M~ = 69,500 g~mol M~/M~ - 2.2; II = 96.3~;

.:

~ 2 ~
- 25 ~
niSo = 66; m.p. = 156C; ~Hmp = 107 J/g.

Example 8 Example 2 was repeated, except that 20.9 mg ~0.05 mmol) of rac-ethylene(2-Me-4,5,6,7-tetrahydro~ indenyl) 2-2irconiumdimethyl were used as the metallocene, The~ctivity of the metallocene was 30.g kg of PP per g of metallocene per h.

VN = 50 cm3/g; M~ - 30,500 g/mol; M~/M~ = 2.1; II = 95.0%;
niSO = 36; m.p. = 144C; ~H~p = 98.5 J/g.

Example 9 A dry 16 dm3 reactor was flushed with nitrogen. 1.6 dm3 (corresponding to 0.1 bar) ~f hydrogen and finally 10 dm3 of liquid propylene and 29.2 cm3 of a solution of methyl~
aluminoxane in toluene (corresponding to 40 mmol of Al, mean degree of oligomeriza~ion 17) were then metered in and were stirxed for 10 minutes at 30C. At the 8ame time, 17.0 m~ (0.035 mmol] of rac-dimethylsilyl(2-Me-4,5,6,7-tetrahydro 1-indenyl) 2zirconium dichloride were dissolved in 11.2 cm3 o~ a solution of methylaluminoxane in toluene (20 mmol of Al~ and the solution was introduced into the reactor after 10 minutes.
Polymerization was carried out at 30C for 3 hours. The metallocene activity was 12.0 kg of PP per g of metal-locene per h.

VN = 110 cm3/g; M~ = 119,800 g/mol, N~/M~ = 2.0; II =
99.8~; nl50 = > 500; m.p. = 162C; ~H~p = 110.9 J/g.

Example 10 The procedure wa~ carried out as in Example 9, except that ~5.0 mg (0.05S mmol) of rac-ethylene(2-Me-4,5,6,7-tetrahydro-l-indenyl)2zirconium dichloride were u~ed.
The metallocene actiYity wa~ 12.5 kg of PP per g o~

~, , ~ , :

metallocene per h.
VN = 66 cm3/g~ M~ = 62,400 g/mol; M~/M~ = 2.2; II - 96.7%;
nlSO = 60; m.p. - 153C; ~9~p = 104.7 J/g.

Example 11 A dry 24 dm3 reac~or was flushed with nitrogen and filled with 12 dm3 of liquid propylene with 4.0 cm3 of a solution of methylaluminoxane in toluene ~corresponding to 6 mmol of ~1, mean degree of oligomerization 17)~ and stirring was carried out for 15 minutes at 30C.

6 cm3 of the toluene-containing reaction mixture of rac-dimethylsilyl(2-Me-4~5~6/7-tetrahydrQ-l-indenyI) zirconiumdimethyl and E Me2N~Ph~B~C6F~)4], which wa~
described in the metallocene synthesis in Section E) (corresponding to 30 mg (0.068 mmol) of metalloce:ne), were then metered into the veseel. Polymerization was carried ou~ for 2 hours at 50C. The metallocene activ-ity was 15.9 kg of PP per g of metallocene per h.

VN = 76 cm3/g; M~ = 70,900 g/mol; ~tM~ = 2.3; II = 96.1%;
ni~O - 65; m.p. = 155C; ~H~p o 104.4 J/g.

Example 12 The procedure was as described in ~xample llr except that 5 cm3 of the toluene-containing reaction mixture of rac-ethylene(2-Me-4,5~6,7-tetrahydro-l-indenyl)2zirconium-dimethyl and tBu3NH][B(C6Hs)4~, which was described in the ~5 metallocene synthesis in Section F) (corresponding to 30 mg tO.073 mmol) of metallocene), were used. The metallocene activity was 24.0 kg of PP per g of metallocene per h.

~N - 50 cm3/g; M~ = 30,100 g/mol; M~ = 2.2; II - 95.0%;
ni~O = 37; m.p. = 142C; ~Hmp~ = 97.0 J/g.

h~;2~J
- ~7 -Example 13 Example ll was repeated, except that a ~olution of tri-methylaluminum in toluene (8 mmol of Al) was used instead of the methylaluminoxane solution. The metallocene activity was 14.0 kg of PP per g of metallocene per h.

VN = 96 cm3Jg; M~ = 64,100 g/mol; Mw/~ - 2.2; II = 96.0~;
niUo = 64; m.p. = 154~C, ~H~p = 107.3 J/~.

Example 14 Example 13 was repeated, except that no trLmethylaluminum was used in the polymerization.

The propylene used was purified with triethylaluminum (1 mmol of AlEt3/dm3 of propylene) before addition to the polymerlzation sy~tem, and the reaction products and AlEt3 were separated off by distillation. The metallocene activity was 15.0 kg of PP per g o~ metallocene per h.

VN = 70 cm3/g; M~ = 65~000 g/mol; M~/N~ - 2.2; II o gfi.~%;
nl90 = 64; m.p. = 155C; QH~p - 106.0 J/g.

Example 15 A dry 16 dm3 reactor was flushed with nitroyen and filled . 20 at 20~C with 10 dm3 of a gasoline cut from which aromatic~
had been removed and which had a boiling range of 100-120Co The ga3 space of the vessel was then flu~hed nitrogen-free by ~orcing in 2 bar of ethylene and letting down the pre~sure,theseoperations beingcarriedout5 time~. 30 cm3 of a solution of methylaluminoxane in toluene (cor-responding to 45 mmol of Al, molecular weight according to cryoscopic determination 750 g/mol) were thsn added.

~he reactor content was then heated to 60~C in the course ~7~

of 15 minutes while stirring, and the total pressure was adjusted to 5 bar by adding ethylene, at a ~tirring speed of 250 rpm.

At the same time, 4.7 mg (0.01 mmol) of rac-ethylene(2-Me-4,5,6,7-tetrahydro-l-inden~l)2æirconium dichloride were dissolved in 20 cm3 of a solution of methylaluminoxane in toluene and were preactivated by allowing the solution to stand fox 15 minutes. The solution was then introduced into the reactor, and the polymerization system was brought to a temperature of 70C and k~pt at this temperature or 1 hour by appropriate cooling. The total pressure was kept a~ 5 bar during this ~ime by appropriate feeding of ethylen~.

550 g of polyethylene were obtained, corresponding to a metallocene activity of 117.0 kg of PE per g of metal-locene per h. The viscosity number was 491 cm3/g.

Example 16 Example 3 was repeated, except that the aluminoxane used was isobutylmethylaluminoxane in the same Al concen-tration and amount. Isobutylmethylaluminoxane was ob-tained by reacting a mixture of isobutylAlMe2 and AlMe3 with water in heptane (9 mol % of isobutyl units and 91 mol % of Ms units). The activity was 9.2 kg of PP per g of metallocene per h and the melting point of the polymer was 159C.

Example 17 Example 3 was repeated, except that the aluminoxane used was hydridomethylaluminoxane in the same Al concentration and amount. Hydridomethylaluminoxane was obtained by reacting Me~hlH with water in toluene (contained 12 mol %
of H units and 88 mol ~ of Me units). The activity was 6.2 kg of PP per g of metallocene per h and the melting point of the polymer was 158C. ~: -~' .

3~2~

Example 18 A dry 70 dm3 reactor was flushed with nitrogen and prop-ylene and filled with 40 ~m3 of liquid propylene. 180 cm3 o~ a solution of methylaluminoxane in toluene (corres-ponding to 270 mmol of aluminoxane, mean degree of oligo-merization p = 17~ were then added and the batch was stirred for 15 minutes at 30C. 50 g of ethylene were then me~ered in. At the same time, 10.6 mg (0.02 mmol) of rac-dimethylsilyl(2-methyl-4,5,6,7-tetrahydro-1-indenyl)~zirconium dichloride were dissolved in 20 cm3 of a solution of methylaluminoxane in toluene (30 mmol of Al~ and were preactivated by allowing the solution to stand for 15 minutes. The solution was then introduced into the reactor and the latter was brought to the poly-merization temperature of 60C in the course of 10 minutes. Polymerization was carried out for 4 hours and a further 100 g of ethylene were metered in continuously duriny this time. The polymeri2ation was stopped with C02 gas, excess gaseous monomer was allowed to escape and ~he product was dried at 80C in a high vacuum. 2.25 kg of a random propylene/ethylene copolymer having an eth-ylenecontentof 6.2%byweightwereobtained.VN = 82 cm3/g~
M~ = 74,500 g/mol, N~/M~ = 2.2, substantially isolated ethylene incorporation with a mean C2 block length < 1 2 (l3C-NMR).

Example 19 Example 1 was repeated with a polymeri~ation ~emperature of 65C but, after polymerization for 3 hours (stage 1), an additional 500 g of ethylene were added, distributed over a polymerization time of a further 3 hours (stage 2). The activity of the metallocene was 78.6 kg o~ C2/C3 block copol~mer per g of metallocene per h. ~he copoly mer contained 18.~ of ethylene. The extractable elastomeric phase content lCz/C3 rubber) was 60%. The product has a very good low-temperature impact strength (a~
according to DIN 53,453, injection molded specLmens) at . ~ . ~ . .
'. ~ ; -, ' ~ '' ' ' '~' ' :

~.53~

23C, 0C and -20C: no fracture, -40C: 62.0 mJ mm~2.
Tha ball indentation hardness taccording to DIN 53,456, compression molded specimens, heated for 3 h at 140C, 132 N) was 36 Nmm 2.

~bbreviations:
Me = methyl, Et = ethyl, Bu = butyl, Ph = phenyl, THF =
tetrahydrofuran, PE = polyethylene, PP = polyprapylene.

Claims

1. A process for the preparation of an olefin poly-mer by polymerization or copolymerization of an olefin of the formula Rn-CH=CH-Rb, in which Ra and Rb are identical or different and are a hydrogen atom or a hydrocarbon radical having 1 to 14 carbon atoms, or Ra and Rb, together with the atoms binding them, may form a ring, at a temperature of -60 to 200°C, at a pressure of 0.5 to 100 bar, in solution, in suspension or in the gas phase, in the presence of a catalyst which is composed of a metallocene as a transition metal compound and an aluminoxane of the formula (II) (II) for the linear type or of the formula III

(III) for the cyclic type, where, in the formulae (II) and (III), the radicals R14 may be identical or different and are a C1-C6-alkyl group, a C6-C18-aryl group or hydrogen and p is an integer of from 2 to 50, wherein the metallocene is a compound of the formula I

(I) in which M1 is a metal of group IVb, Vb or VIb of the Periodic Table, R1 and R2 are identical or different and are a hydrogen atom, a C1-C10-alkyl group, a C1-C10-alkoxy group, a C6-C10-aryl group, a C8-C10-aryloxy group, a C2-C10-alkenyl group, a C7-C40-arylalkyl group, a C7-C40-alkylaryl group, a C8-C40 arylalkenyl group or a halogen atom, R3 and R4 are identical or different and are a hydrogen atom, a halogen atom, a C1-C10-alkyl group which may be halogenated, a C6-C10-aryl group, a -NR215, -SR15, -OSi-R315, -SiR315 or -PR215 radical, in which R15 is a halogen atom, a C1-C10-alkyl group or a C6-C10-aryl group, R5 and R6 are identical or different and have the meaning stated for R3 and R4, with the proviso that R5 and R6 are not hydrogen, R7 is =BR1l =A1R11 Ge-, -Sn-, O-, -S-, =SO, =SO2, NR11, =CO, =PR11 or =P(O)R11, where R11, R12 and R13 are identical or different and are a hydro-gen atom, a halogen atom, a C1-C10-alkyl group, a C1-C10-fluoroalkyl group, a C6-C10-aryl group, a C6-C10-fluoroaryl group, a C1-C10-alkoxy group, a C2-C10-alkenyl group, a C7-C40-arylalkyl group, a C8-C40-arylalkenyl group or a C7-C40-alkylaryl group, or R11 and R12 or R11 and R13 together with the atoms binding them, each form a ring, M2 is silicon, germanium or tin, R8 and R9 are identical or different and have the meanings stated for R11, m and n are identical or different and are zero, 1 or 2, m plus n being zero, 1 or 2, and the radicals R10 are identical or different and have the meaning stated for R11, R12 and R13.

2. The process as claimed in claiLm 1, wherein, in the formula I, M1 is Zr or Hf, R1 and R2 are identical or different and are methyl or chlorine, R3 and R4 are hydrogen, R5 and R6 are identical or different and are methyl, ethyl or trifluoromethyl, R7 is a radical or n plus m is zero or 1 and R10 is hydrogen.

3. The process as claimed in claim 1 or 2, wherein - 34 _ the compound of the formula I is rac-dimethylsilyl(2-methyl-4,5,6,7-tetrahydro 1-indenyl)2zirconium dichloride, rac-ethylene(2-methyl-4,5,6,7-tetrahydro-1-indenyl)2zirconium dichloride, rac-dimethylsilyl(2-methyl-

4,5,6,7-tetrahydro-l-indenyl)2zirconiumdimethyl or rac-ethylene(2-methyl-4,5,6,7-tetrahydro-1-indenyl)2-zirconiumdimethyl.

4. The use of a metallocene of the formula I as claimed in one or more of claims 1 to 3 as a catalyst in the preparation of an olefin polymer.

5. An olefin polymer which can be prepared by the process as claimed in one or more of claims 1 to 3.