CA2069603A1 - Process for the preparation of syndiotactic polyolefins having a broad molecular weight distribution - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Process for the preparation of syndiotactic polyolefins having a broad molecular weight distribution Syndiotactic polyolefins having a molecular weight distribution Mw/Mn of ? 3 and which may be monomodal, bimodal or multimodal are obtained by polymerization or copolymerization of olefins of the formula RCH=CHR, in which a catalyst system comprising an aluminoxane and a transition-metal component (metallocene) is used, the transition-metal component comprising at least 2 metal-locenes of the formula

Description

-- 2 ~ 3 ~OEC~ST A~TIENGEsEL~c~aFT - ~V~ 91/F 159 Dr~ ~0/8ch Description Process for the preparation of ~yndiotactic polyolefins having a broad molecular weight distribution It is known that metallocene catalysts in co~bination with aluminoxanes as cocataly~ts are capable of polymerizing olefins to gi~e polyolefins ha~ing a narrow molecular w2ight distri~utio~, N~/N~ ~ 2-3 l~ Polym .
SCi ., PQ1 . Chem. Ed . 23 ( 19a~ ) 2117 , EP-A 302 424 J .

Polyolefins of this type with a narrow di6tribution are suitable, for ex~mple, for applications in precision : injection molding, in~ection molding in general and for the production of fibers. For numerous applications, such as, for example, thermoforming, e~trusion, blow molding and for the production of polyolefin foams and films, broader or bimodal molecular weight distributions are required.
:
: For polyethylene, it has bee~ proposed to achieve such products by using two or more metallocene cataly9t6 in ~ 20 the polymerization (EP-A 128 045). The sy~tems described : are achiral catalysts and would gi~e atactic poly--~ propylene on pol~mermization of propene. Ho~e~er, atactic polypropylene is unsuitable as a structural material.

~he preparation of ~tereoblock polypropylene where N~/M~
is 13-lS ;~ disclosed in DE-A 3 640 924. These c~talyst ~ystems are likewise unsuitable for the formativn of polyole~ins of high tacticity. Furthermore, the molecular weights which can be achie~ed at indu~rially relevant polymerization temperatures are too low.

EP-A 310 734 proposes polymerization system~ comprising a mixture of a hafnocene and a zirconocene, both of which are chiral and ~tereorigid, for the preparation of highly ~, . .

2 ~
~ 2 --isotac~ic polypropylene. The products obtained have broad to bimodal distributions where N~/M~ is from 3.7 to 10.3 If only a hafnocene catalyst is u~ed, isotactic polypropylene with a broad distribution is obtained at a S certain polymerization temperature~ according to EP-A 355 439.

Syndiotactic polypropylene having a broad or bimodal distribution (N~/N~ ~ 6.4) is prepared in EP-A 387 691 using a hafnocene catalysk.

These processes have the disadvantages of hafnium catalyst rosts which are too high for industrial applica-tions, tog~ther wi~h a low polymerization activityr which additionally makes it necessary to carry vut thoroughr high~cost purifica~ion of the prepaxed polymer to remove catalyst residues.

The object was thus to find a catalyst system and a process by means of which syndiotactic polyole~ins ha~ing a broad to ~imodal distribution can be prepared and which are suitable for industrial applications.

The o~ject is achieved by using a catalyst sy~t~m com-prising at least two specifiG zirconocenes, which are i`~ stereorigid and prochiral, but are not necessary chiral, and which have C~ symmetry or only slightly distorted C~
~: symmetry, and an aluminum compound as cocataly~t.

The invention thu~ relate~ to a process for the prepara-tion of a syndiotactic polyolefin which ha~ a molecular weight distribution N~/N~ of 2 3.0 and which may be monomodal, bimodal or multimodal, by polymerization or ~, copolymerization of an olefin of the formula ~nCH=CHRb in which R~ and Rb are identical or different and areahydro-1,~,. gen atom oraal~yl radical having 1 to 14 carbon atoms, :1' or R~ and Rb, together with the atoms connecting them, can ~; form a ring, at a temperature of from -60 to 200~, at a ,; .

i'` ~' ~ " ' , , ~.',',' ~ ~ , ~'. '' ~; ' ' .

pressure o~ fr~m 0.5 to 100 bar, in solution, in suspen-sion or in the gas phase, in the presence of a cataly t comprising a transition~metal comp~nent (metallocen2~ and an aluminoxane of the formula II

R~ R~
5 ~ ~ - O .~ .~
: R~ _ ~' for the linear type and/or of the formula III
r~
tA~
n~2 for the cyclic type, where~ in the ormulae II and III, the radicals R9 may be identical or different and are 10aCl-C6-alkyl group, aCl-C6-fluoroalkyl group, a C6-Cla-aryl group, aC6-Cla fluoroaryl group or~hydrogen, and n is ~n .~ integer from O to 50, or, instead of the aluminoxane, comprises a mixture of an al~minoxane of the formula II
and/or of the formula III with a compound AlR93, which ~: 15comprises using, as the tran~itivn-metaI component, at ~:~least 2 metallocenes of the formula I

~a R
~ Zr ~) :~.' \ ''R2 R' ,; .
~i ~

.,~which are stereorigid and whose moiety formed by Zr and . i , ~ ~

:

- g -the substituents Rl-R4 has Ca ~ymmetry or slightly distorted C~ symmetry, and in which R1 and R2 are identical or different and ar~ hydrogen atoml ~ halogen atom, a Cl-C1O-alkyl group,~a Cl C10-alkoxy group, ~ C6-C10-aryl group~ ~C6-C1O-aryloxy group, a C2-C10-alkenyl group~
aC7 C40~arylalkyl groupg~ac7-c~o-alkylaryl group o~ a CB_C40-arylalkenyl groupt R3 and R4 are di~erent and are monocyclic or po~ycyclic hydrocarbon radicals which can form a sandwich struc~ure together with the central atom Zr, F~ R~ R6 R8 Rfi R3 R~ ~
Rs is M~ M~M1~ -M'~CR8~ C;, -O~M~ C~G-, ~7 R~ R7 ~7 ~ R' ~7 ~7 aBR6, =AlR~, -Ge-, Sn, ~O-, -S-, =SO, =SO2l -NR6, =CO, =PR~ or =P(o)R6, where R6,R7 and R8 are identica~ or different and are~hy~rogen atom,a halogen atom,a C1-~10-alky~ groupt a Cl-C1O-fluoroal~yl group,a C6-ClD-fluoroaryl group, a C6-C10-aryl groupt aCl-clo-alkoxy group, a C2-C10-- alkenyl group~ .aC7-C40-arylalkyl group,~- C~-C40-arylal]cenyl -~ group or aC7-C40~alkylaryl group, or R6 and R7 ox R6 and R8, together with the atoms connecting them, in each ca6e form a ring, and M1 is ~ilicon, germanium or tin.
, .: Alkyl here is straight-chain or branched alkyl and halogen i~ preferably fluorine or chlorine, in particular chlorine.
.
~ Por khe purposes of the present invention, the term C~
25 symmetry means that the metallocenes I have a mirror plane in the Zr, R1-R4 moiety perpendicular to the plane passing through Zr, R1 and R2. The bisecting line of the anglQ R1-Zr-R2 extends in this mirror plane.
~.

.. .

:~:

In the case of slightly distorted CD s~mmetry, R1 may be different from R2 or ~he radicals R3 and/or R4 are substituted (such as, for example, methylcyclopenta-dienyl~. Preferred metallocenes are those whose C~
symmetry is not distorted.

;: It should be noted here that the term CD symmetry ~nd its scope of meaning are determined by a formal (idealized) consideration of the metallocene molecule I. This means that shifts in said moie~y, for example caused by the bridge R5, which wou~d arise in a complete structural determination (X-ray structural analysis) and could not be regarded a~ C~-symmetrical if considered strictly, remain unconsidered for the purposes of the pre~ent invention.

The following also applias to the formula I:

Rl and R2 ~re identical or diferent and areahydrogen atom~ a C1-C10-l preferably C1-C3-alkyl group~ a C1-C~
preferably C1-C3-alkoxy group, aC6-C10-, preferably C5-C8-aryl group~ a C6-C10-, preferably C6-C8-aryloxy group, a C2-C10-, preferably r2-C4-alkenyl group, a C7-C40-, prefera-bIy C7-C10-arylalkyl groupla C7~C40-, prefera~ly C7-C12-alXylaryl group, a C8-C40-, preferably C~-Cl2-arylalkenyl group, or ahalogen atom, preferably chlorine, R3 and R4 ~ are different and are monocyclic or polycyclic : 25 hydrocarbon radical~ which can ~orm a 6andwich structure together with the central atom Zr.

: R3 and R4 are preferably fluorenyl and cyclopentadieny}, it ~eing possible for the parent structures to carry additional substituents as defined for R6.

R5 is a single- or multimembered bridge which links the radicals R3 and R4 and is :

2 ~ 3 R3R~ R~ R~ 3 R8 R3 F3a M~- . -M~ 2~ -M~
R7F3~ R7 F~? Rr R7 R? P~7 =BR6, =AlR6, -Ge-, -Sn, -O-, -S-, =SO~ =SO2~ =NR6, =CO, =pR6 or =P~o)R6, where R6, R7 and R8 are identical or different and are ahydrogen atomt a halogen atom.~
preferably chlorine, a Cl-Cl~-, pre~erably Cl-C3-alkyl group, i~ particular methyl group.r~Cl~ClD fluoroal~yl group., preferably CF3 grou~, 2 C6-C1O-~l~oroary~ group, preferably pentafluorophenyl groupj.,~ C6-C1D-~ preferably C6-C8-aryl group, a Cl-C10-, preferably Cl-C4-alkoxy group~
in particulax methoxy group~.aC2-C10-, preferably C'2-C4-alkenyl group, a C7-C40-, preferably C7-Cl~-arylalkyl group, aC~-C40-, preferably C8~Cl2~axylalkenyl group~ or aC7-c40~ preferably C7-Cl2-slkylaxyl groupp or R6 and R7 or R6 and R8, toge~her with the a~oms connecting them, in :: 15 each case form a ring.
,~:
.~ Ml is silicon, germanium or tin, preferably silicon or germanium.

: R5 is preferably -CR5R7, =5iR5R7, =GeR6R7, -O-, -S-, =SO, =p~6 or =P(O~Rb. ~he above-described metallocenes can be prepared by the general reaction scheme belowo , H2R3 + butylLi - HR3Li X-R5-X~ HR3_RS_R4E 2-But~lLi~
H2R4 + butylLi - HR4Li LiR3~R5-R4Li ZrCl ~ ,;

,~
, ~; :

:.

2 ~ 3 ~ 3 /' Cl /- ~Rl ~/ ' Rl \ ~ ~ Cl ~ \ ~ Cl R ~,j' ~R2 R4 ~4 R4 X = Cl, Br, I, O-tosyl ) or : H2R3 t butylLi ~ HR3Li ;~ ~ R4 b, 11~0 6 ~ R ~1 ~ R3H
~::`
2 butylLi ~ 3 R C ~ Li;2 L'~
ZrCl 4 , : :
,, , ,, ~ i .

, 2 ~ 3 ~ -- 8 --6 / ~ ,~ t~l C ~r R7/' \, Cl : R4 R1~
.

R3 E~.3 ~6 / ' R,1 R6 / I R1 C Z~ /C Zr R7 \ ' ~ Cl ~4 `i :~
' `:

cf. Journal of Organomet. Chem. (1985) 63-67 arld EP-A 320 762 ) .

The choice of *he metallo~e~es for the polymerization of olefins to give polyolefins~having a broad or multimodal distribution can take :~place by means of a test polymerization for each metall~cene ~cf. working examples). In this test,~the olefin is pol~meri~ed to the polyolefin and the mean molecular weight M~ thereof and ~; 10 ~he molacular weight distribution ~w/N~ thereof are determined ~y mean~ of gel permeation chromatography.
~ : Depending on the desired molecular weight distribution, '~. the metallocenes are then combined. Taking into a~count the pol~merization activities, it is then possible, ~or example by means of comput~r simulation of the combined gel permeation curves, to directly produce any desired moIecular :weight di~tribution via the type of metallocenes~ and via ~he ratio of the amount~ of the : metallocenes to one another. ~ ;

_ 9 _ The number o~ metallocenes I to be used accordi~g to the invention is pre~erably 2 or 31 in particular ~. H~we~er, it is also possible ~o use a greater number (such as, for example, 4 or 5).

By including the polymerization activities and molecular weights at various pol~merization temperatures, in the presence of hydrogen a~ molecular weight regulator or in the presence of comonomers, ~he computer simulation model can be further refined and the applicability of the process according to the invention further improved.

Pref~rred metallocenes are (arylalkylidene)(9-fluorenyl)(cyclopentadienyl)zirconium dichloride, (dia~ylmethylene3(9-fluorenyl)(cylcopentadienyl)zirconium : dichloride and (dialkylmethylene)(9-fluore~yl) (cyclopentadienyl)zirconium dichloride.

P art icu lar pre ference is given to (methyl(phenyl)methylene)(9-fluorenyl)(cyclopentadi~nyl)-zirconium dichloride, ~ diphenylmethylene) (9-fluorenyl)-(cyclopentadienyl)~irconium dichloride and (dLmethylmeth-ylena ~ ( 9 - f luorenyl ) ( cyc lopentadienyl ) ~ irconium dichloride.

The cocatalyst used is an aluminoxane of ~he formula II
and/or III, where n i~ an integer from 0 to 50, prefera-bly lO to 35.
~, The radicals R9 are preferably identical and are methyl, isobutyl, phenyl or benzyl, particularly preferably methyl.

If khe radical~ Rg are different, they are preferably methyl and hydrogen or alternatively methyl and isobutyl, hydrogen or isobutyl preferably being pre~ent to the :~ ex~ent of 0.0l-40% (number o~ radicals R9~.

': :
, . .

: : . .
.

2 ~

The aluminoxane can be replaced as cocatalyst by a mixture comprising aluminoxane and AlR93. The aluminoxan~
can be prepared in various ways by known processes. One of the methods is, for example, to react an aluminum hydrocarbon compound and/or a hydridoal~uninum hydrocarbon c~mpound with water (gaseous, solid, liquid or bound -for example as water of crys~allization) in an inert solvent tsuch as, for example, to1uene). To prepare an aluminoxane containing different alkyl groups R9, two 1~ different trialkylaluminum compounds ~lR3 ~ AlR~
corresponding to th~ desired composition, are reacted with water ~of. S. Pasynkiewicz, Polyhedron 9 (1990) 429 and EP-A 302 424~.

The precise strncture of the aluminoxanes II and III is unknown.

Irrespective of the preparation me~hod, all aluminoxane solutions have in com~on a varyinq content o~ u~reacted aluminum starting compound, which is in ree form or as an adduct.

It is possible, before use in the polymeriza~ion reac-tion, to preactivate the metallocenes, in each case separately or together as a mixture, by mean~ of an aluminoxane of the formula (II) and/or (III). This significan~ly increases the polymerizat}on actiYity and improves the particle morphology.

The preacti~ation of the metallocenes is carried out in 601ution. The metallocenes are preferably di~solved, as solids, in a solution of the aluminoxane in an inert hydrocarbon. Suitable in~rt hydrocarbons are aliphatic or aromatic hydrocarbons. Toluene or a C6-C10-hydrocarbon is preferably used.

The concentration of the aluminoxane in the solution is in the range from about 1% by weight to the saturation limit, preferably from 5 to 30~ by weight, in each case ' 2 ~

based on the ~otal solution. The metallocenes can be employed in the same concentration, but are preferably ~mployed in an amount of ~rom 10-4-l mole per mole o aluminoxane. The preactivation time is from 5 minutes to 60 hours, preferably from 5 to 60 minutes. The tempera-ture used is from -78~C to 100C, preferably from 0 to 70C.

The metallocenes may al~o be prepolymeriz~d or applied to a ~upp~rt. Prepol~merizati~n is preferably carried out using the (or one of the) vlein(s) employed in the polymeriza~ion.

~xamples of suithble ~upports are silica gels, aluminum oxides, solid aluminoxane or other inorganic su!pport materials. Another suitable support material iB a poly-olefin powder in finely divided form.

A further possible embodimen~ of the process according to the invention comprises using a salt-like compound o~ the : formula RXNH4XBR~4 or of the formula R3PHsR~4 as cocatalyst in place o or in addition to an aluminoxane. In these formulae, x = 1, 2 or 3, R = alkyl or aryl, identical or different, and R' = aryl~ which may also ~e fluorinated or partially fluorinated. In this case, the catalyst comprises the product of the reaction of the ~etallooenes with one of said compounds (cf. BP-A 277 004).

In order to remove the catalyst poisons present in the ~:~
olefin, purification by means of an alkylaluminum com-pound, for example AlMe3 or AlEt3, is advantageous. This purification can be carried ou~ either in the polymerization system itself, or the olefin is brought into contact with the Al compound before addition to the polymerization system and is suhsequently removed again.
.;;: ~ , The polymerization or copolymerization is carried out in a known manner in solution, in suspension or in the gas phase, continuously or batchwise, in one or more steps, ; :
, ; ~ ~ - . :

2 ~

at a ~emperature of from -60 to 200C, preferably from 20 to 80C. Olefins of ~he formula Ra-CH=CH-~b are polymeri2ed or copolymerized. In this formula Ra and Rb are identical or different and are hydrogen atoms or alkyl radicals having 1 to 14 carbon atoms. However, R~
and Rb may also form a ring with the carbon atoms con-necting them. Examples of such olefins are ethylene, propylene, l-~utene, 1-hexene, 4-methyl-1-pentene, l-octene, norbornene and norbornadie:ne. In particular, propylene and ethylene are polymerized.

If necessary, hydrogen is added as molecular ~eight regulator.

The overall pressure in the polymerization system is fxom O.5 to 100 bar. ~he polymerization i~ preferably carried out in the indu~trially particularly interesting pre~sure range of from 5 tQ 64 bar~
~ :;
The metallocenes are used in a concentration, based on ~; the tran~ition metal, of from 10-3 to 10-8 mol, preferably from 10-4 to 10-7 mol, of transition metal per dm3 of solvent or per dm3 of reactor volume. The aluminoxane or the aluminoxanetAlR93 mixture is u~ed in a concentration of from 10-5 to 10~1 mol, preferably from 10-4 to 10-2 mol, per dm3 of solvent or per dm3 of reactor volume. In principle, however, higher concentrations are also possible.
..
If the polymerization i5 carried ou~ as a suspension or solution polymerization, an inert solvent whLch is customary for the ~iegler low-preæsure proce~s i8 U8ed.
~or example, the polymerization is carried out in an ~ 30 aliphatic or cycloaliphatic hydrocarbon; the examples of .~ these which may be mentioned are butane, pentane, hexane, : heptane, decane, isooctane, cyclohexane and methylcyclo-i~ hexane. It is al80 possible to use a gasoline or hydro-~:: genated diesel oil fraction. Toluene can also be used.
The polymerization is preferably carried out in the i/

:., `~:
''s~` ~

liquid monomer~

If inert sGlvents are used, ~he monomers are metered in in gaseous or li~id fonm.

The polymerization can take as long as de~ired, since the catalyst system used according to the invention only exhibit~ a slight decraa~e in ~he polymerization acti~ity with tLme.

The proces~ according to the in~ention is distinguished by ~he act ~hat the metallocenes described gi~e polymers ; 10 having a broad, bimodal or multimodal molecular weight distribution, high molecular weight~ high syndiotacticity and good particle morphology in the industrially inter-esting temperature range between 20 and dOC with high polymerization activity.

The polymers according to the invention are particularly : suitable for the production of films, in particular transparent films, thermoforming applications, polyolefin foams, extxusion applications and for the production of transparent hollow article6 and for blow molding in general.

The examples below are intended to illustrate the inven-tion in greater detail.
. ~
~ The following abbreviations are u~ed:
~, .
~ : VN = ~iscosity number in cm3~g : ~5 M~ = weight average molecular 1 determined by weight in g/mol I gel permeation $ M~ = numbe.r average molecular chromatography weight in g/mol ~; M~/M~ = molecular weight dispersity ~ 30 (=molecular weight distribution) '~t,~ SI = syndiotactic index (SIrr + 1/2 ~r) determined by 13C-~;~ NMR spectroscopy n~ = syndiotactic block length ~, .,:

~ . . ..
:!:

;:~ -. :

2 ~ 3 MFI (230/5) = mel~ flow index, measured in accordance with DIN 53735; in g/10 min.

A. Preparation of sui~able metallocenes All the working operations given below in the synthesis of metallocenes were carried out under a protective g~s using absolute ~olvents.

Example 1 ~Phen~l~methyl)met~ylene)(9~fluorenyl)~c~clopenta~ienyl)-zirconi~m dichloride Ph ~ / C1 ~C ~r ~
Me ~ Cl :`~

:~ A solution of 67.8 mmol of fluorenyllithium in 50 cm3 of THF was added at room temperature to a 501uti~n of 11.4 g (67.8 mmol) of 6-methyl-6-phenylfulvene in 40 cm3 of THF. The mixture was stirred a~ room temperature for 2 : 15 hours, and 60 cm3 of water were added. The ~ubs~ance : which precipitated was filtered off with suction, washed with diethyl ether and dried in an oil-pump vacuum.
19.1 g (84.2%~ of 2,2-cyclopentadienyl(9-fluorenyl)ethyl ~enzene (correct elemental analyses; ~H-~MR spectrum) were obtained.

10.O g (29.9 mmol) of the compound wexe dissolved in 60 cm3 of THF, and ~6 cm3 (65 mmol) of a 2.5 molar hex~ne solution of n-butyllithium were added at 0C. After the mixture had been tirred for 15 minutes, ~he solvent wa~
stripped off in vacuo. The dark red residue which remained wa~ washed several times with hexane and dried - .
`.`' ' '~ ' : .

2 ~

in an oil-vacuum. 15.6 g of the red dilithio salt were obtained as ~he THF adduct; it contained about 30~ of THF.

14.9 mmol of the dilithio salt were added at ~78C to a suspension of 3.48 g tl4.S mmol) of ZrCl4 in 70 cm3 of CH2Cl2. After the batch had been ~lowly warmed to room temperature, it was stirred at roo~ temperature for a further hour and filtered through a G4 rit; the residue was washed ~everal times with CH2C12. The red filtrate was evaporated to drynes~ and the orange-red residue was recrystallized from CH2Cl2- 1.8 g (25%) of methylpher~rlmethylene ( cyclopentadienyl ) ~ 9-f luorenyl ) zir-conium dichloride were obtained as a pink crystal powder.
1H-NMR spectrum ~100 M~z, CDCl3): 7.1 - 8.25 (m, Flu-H, Ph-H)~ 6.90 ~m, Ph-H), 6.10-6.50 (m Ph-H, Cp-H), 5.90, 5.75 (2 x m/ Cp-H), 2.5$ (s, CH3~.

Example 2 Diphenylmethylene(g-fluorenyl)(cyclopentadienyl)zirconium dichloride ' ~

Ph \ ~ Cl ~C ~r ~
Ph ~ Cl '`':
~ .
' 12.3 cm3 (3n.7 mmol) of a 2.5 molar hexane solution of n-butyllithium were added ~lowly at room temperature to a ; solution of 5.10 g (30.7 mmol) of fluorene in 60 cm3 of : THF. After 40 minute~, 7.07 g (30.7 mmol) of .. 25 diphen~lfulvene ~ere added to the orange solution, and :~ the mixture was ~tirred o~ernight. 60 cm3 of water were ::

- 2 ~ 3 added to the dark red solution, the solution becoming a yellow color, and the solution wa6 extracted with ether.
The ether phase was dried over ~gSO4, evaporated and left to crystallize at -35DC. 5.1 g (42%) o l,l-cyclopentadi-enyl(9-fluorenyl)diphenylmethane were obtained as a beige powder.

6.4 cm3 (10 mmol) of a 1.6 molar solution of butyllithium in hexane were added at O~C to 2.0 g ~5.0 mmol) of the compound dissol~ed in 20 cm3 of THF. The mi~ture was stirred at room temperature ~or 15 minutes, the solvent was stripped off, and the red residue was dried in an oil-pump vacuum and wa~hed se~eral times with hexane.
~fter drying in an oil-pump ~acuum, the red powder was added a~ -78C to a suspension of 1.16 g (6.00 mmol) of ZrCl4. The ~atch was slowly warmed and then stirred at room temper~ture for 2 hours. The pink suspension was filtered through a G3 frit. ~he pink residue was washed with 20 cm3 ~f CH2C12, dried in an oil-pump vacuum and extracted with 120 cm3 of toluene. The solvent wa~
stripped off and ~he residue wa~ dried in an oil-p~mp vacuum, giving 0.55 g of the zirconium complex in the form of a pink cry~tal powder.

The orange-red filtrate from the reaction batch was evaporated and left to crystallize at -35C. A further a . 45 g of the complex crystallized from CH2C12. Total yield l.0 g (36~). Correct elemental analy~es. The mass spectrum ~howed M~ = 556. 1H NMR spectrum (100 N~z~
CDCl3); 6.90-8.25 (m, 16, Flu-H, Ph-H), 6.40 ~m, 2, Ph-X~, 6.37 tt, 2, Cp-H), 5.80 (t, 2, Cp-H~.

Themetallocenedimethylmeth~lene(fluorenyl)tcyclopentad ienyl)zixconium dichloride was prepared as described in the refere~ce J. Am. Chem. Soc. 110 ~1988~ 6255.

In order to specifically prepare the desired molecular weight distribution M~M~ (width of the molecular weight distribution, monomodal, bimodal or multimodal), the ' , :

. ~
. ~
i ' : . ':

-- 17 .w employed to this end in the combination must be known. To this end, at least one test polymerization is carried out for each of the po~si~l~ metallocenes.

The examples below demonstrate, with reference to three suitable metallocene~, the procedure and the possible me~allocene combinations for ~he preparation of ~he broad or multLmodal molecular weight distri~ution according to the invention.

Test polymerizations Example 3 A dry 16 dm3 reactor was flushed with nitrogen and filled with 10 dm3 of liquid propylene. 30 cm3 of a tol~ene solution of methylaluminoxane ~corresponding to 40 mmol of Al, mean degree of oli.gomexization of the methyl-aluminoxane n = 20) were then added, and the batc:h was stirred at 30C for 15 minutes. In parallel, 11.9 mg (0.023 mmol) of diphenylmethylene(9-fluorenyl)(cyclopent-`: adienyl)zir~onium dichloride were dis~solved in 15 cm3 of a toluene solution of methylaluminoxane ~20 mmol of ~1).
~: 20 After 15 minutes, ths solution was introduced in~o the reactor, and the polymerization temperature was increased to 60C. After a polymer~2ation tLme of 1 hour, the polymerization was terminated. 0.95 kg of polypropylene were obtained, corresponding to a metallocene activity of 79.8 kg of polypropylene/g of metallocene x h.
I' VN = 459 cm3/g; M~ = 547,000, M~ = 188,000, NW/Nn = 2.9, SI = 96.$%; n~yn = 38.4; NFI 230/5 = < 0.1 g/10 min.

~ . Example 4 ;'. The procedure was a~alogou~ to Example 3, but 13.5 mg . 30 (O.C27 mmol) o phenyl~methyl)methylene(9-fluorenyl)-(cyclopent~dienyl)zirconium dichloride were employed.
1 O.g4 kg of polypropylene were obtained, corre~ponding to :' a metallocene activity of 69.5 kg of polypropylene/g of metallocene x h.
I 35 VN - 364 cm3/g; M~ = 490,00~ g/mol; M~ 2.6;

,~
. . .

`: :

2 ~

SI = 97.0~; n~ = 40.2; MFI (~30/5) = 0.25 g/10 min.

Example 5 The procedure was analogous to Example 3, but 13.9 mg (O.032 mmol) of dLmethylmethylene(9-~luorenyl)(cyclopent-adienyl~.irconium dichloride were employed. After apolymerization ~ime of 2.5 hour3, 2.56 kg of polypropylene were obtained, corresponding to a metal-locene activity of 73.7 kg of polypropylene~g of metal-locene x h. VN = 12S cm3/g; M~ = 95250 g/mol; M~M~ = 2.1;
SI = 94.6%; MFI (230/5) = 55 g~10 min.

Examples 3 to 5 show ~hat, for example by ~arying the radical R5 in fo~mula I
Me Ph Ph Rs s ~
Me M0 Ph (a) (b) ~c~

polymers of low (a), medium ~b) and high ~c) molecular weight can be prepared. Other modifications of the metallocene ligand sphere of the compounds of the formula I gi~e comparablR differences. The combinations according to the invention of ~uch metallocenes gi~e products : having the broad or multLmodal molecular weight distributions according to the invention and are de~c-ribed in greater detail in the examples below.

Preparation of polymers having a broa~ and/or bimodal molecular weigh~ distribution Example 6 :~ 25 The procedure was analogous to Example 3, but the metallocene component was a mixture of 11.9 mg (Q.023 ~:~ mmolJ of diphenylmethylene(9-fluorenyl)(cyclope~tadienyl?-.
.
~;

:~ , .. . ~ .

.. . .
::

2 ~

zirconium chloride and 12.9 mg (O.030 mmol) o dLmethyl-methylene(9-fluorenyl) Icyclopentadienyl)zirc:onium dichloride in 15 cm3 of the toluene solution of methyl-aluminoxane. 2.05 kg of polyprop~lene, were obtained, corresponding to a metallocene mixture activity of 82.7 kg PP/g of metallocene mi~ture x h.
VN = 291 cm3/g; ~ - 215,~00 g/mol, M~/N~ = 5.0 bim~dal;
Sl = ~6.1%~

Example 7 Example 6 was repeated, but 11.9 mg (~.023 mmol~ and 6.5 mg ~0.015 mmol3 of the metallocenes were used. 1.35 ~g of polypropylene were obtained, correspvndiny to 73.0 kg of : PP/g of metallocene mixture x h.
.. VN = 353 cm3/g; N~ = 285,50~ g/mol, M~/N~ - 5.4 bLmodal;
SI = 96.8~.

Example 8 Example 6 was repeated, but 6.0 mg (O.~11 mmol) and 12.9 mg (O.030 mmol) of the metallocene~ were used.
1.35 kg of polypropylene were obtained, corresponding to 71.4 kg of PP/g of metallocene mixture x h.
VN = 226 cm3/g; N~ = 168,500 g/mol, N~ = 4.7/ bimodal;
: SI = 96.0~.

Example 9 Example 6 wa~ repeated, but 20.0 mg (O.036 mmol) and ~5 4.4 mg (O.Ola mmol) of the metallocenes were u~ed.
1.87 kg of polypropylene were obtained, corresponding to 76.6 kg of PP~g of metallocene mi~ture x h.
VN = 423 cm3/g; M~ = 327,000 g/mol, N~/M~ = 5.9, SI Q 96.6%.

Example 10 Example 6 wa~ repeated, but 4.0 mg (0~007 mmol) and 16.3 mg ~O.038 mmol) of the metallocenes were used.
1.45 kg of polypropylene were obtained, corresponding to 71.4 kg of PP/g of metallocene mixture x h.
V~? = 167 cm3/g; M~ 110,000 g/m~l, M~ = 40O;

- ~o -VN = 167 cm3/g; M,,, = 110,000 g/mol~ /M~ = 4.0;
SI = 95.9~, Example 11 A dry 150 dm3 reactox was flushed wi~h nitrogen and filled at 20C wi~h 80 dm3 of a gasoline fraction with the aromatics removed and with a boiling range of 1~0-120~C. The gas 6pace was ~hen flu~hed ~r~e rom nitrogen by in~ecting 2 bar of propylene and releasin~ the pre~-sure and repeating this cycle four times.

50 1 of li~uid propylene were added, and 320 cm3 ~ a toluene solution of methylaluminoxane ~corresponding to 500 mmol of ~1, molecular weight 1180 g/mol according to cryoscopic determination), and the reactor contents were heated to 40~C. Hydrogen was metered in to give a hydrogen content in the gas space of the xeactor of 0.1%
by volume, and this con~ent was then maintained during the entire pol~nerization time by topping up ~on-line gas chromatography).
19.1 mg (0.039 mmol) of phenyl(methyl)methylene(9-fluore-nyl)(cyclopentadienyl)zirconium dichloride and 21.5 mg (0.089 mmol) of dip~enylmethylene(9-fluorenyl)(cyclo-pentadienyl)zirconium dichloride were mixed, and the solid was dissolv~d in 96 ml ~f a toluene solution of methylaluminoxane (corresponding to 150 mmol of Al) and, af~er lS minutes, the solution was introduced into the reactor. The polymerizatio~ system was ~ept at 40C ~or : 5 hours by cooling. The polymeri~ation was terminated by addi$ion of 2 bar of C~2 ga~, and the polymer formed was ~eparated ~rom the suspen~ion medium in a pre~suxe filter. The product iB dried for 24 h~ur~ at B0C/200 mbar. 15.3 kg of polymer powder were obt~ined, corres-ponding to an activity of the metallocene mixture of 75.2 kg of PP/g of metallocene mixture x h.
VN = 523 cm3/g; MW = 368,000 g/mol; M~/M~ - 4.2 bimodal;
~ 35 SI = 97.4%.
'~
Example 12 ; ;-. ` `

.

Exam~le 11 was repeated, but 19.1 mg t0.039 ~mol) and 11.0 mg (0.020 mmol) of the metallocenes were used and the polymerization temperature was 37~C. 9.7 kg of polymer powder were obtained, corresponding to an activity of 64.5 kg of PP/g of metallocene mixture x h.
VN = 428 cm3/g; k~= 326,000 g/mol; ~/M~ = 3.4;
SI = 97,2%, -~xample 13 Example 11 wa6 repeated, but 6.0 mS~ ~0.012 mmol3 and 12.4 mg ~O.022 mmol) of the metallocenes were used and the polymerization tims was 7.5 hours. 9.5 kg of polymer powder were obtained, corresponding to an a~ti~i~y of 68.8 kg of PP/g of metallocene mi~ture x h.
~N - 618 cm3/g; M~ - 457,000 g/mol; N~/M~ = 3.4 bimodal;
SI - 97.0~.

Ex~mple 14 `~ ~xample 11 was repeated, but ~0.0 mg (0.040 m~ol) and 4.8 mg (0.009 mmol) of the metallocenes were used. The ~: polymerization temperature was 35C. 8.8~ kg of polymer i 20 powder were obtained, corresponding to an activity of 71.4 kg of PP/g of metallocene mixture x h.
VN = 321 cm3/g; M~ = 223,500 g/mol; M~/Mn = 3.1;
SI = 96.5%.

~:~ Example 15 ~: 25 Example 11 was repeated, but 7.9 mg (0.0~6 mmol) and 44.3 mg ~0.080 mmol3 of the metallocenes were used. No h~drogen wa~ u~ed, an~ the polymerization temperature wa~
44C. 16.7 kg of pol~mer powdex were obtained, corresponding to an activity of 63.9 kg of PP~g of metallocene mixture x h.
VN - 766 cm3/g; M~= 537,000 g/mol; M~ = 3.4;
SI = 97.0~.
!
Example 16 A dry 24 dm3 reactor was flushed with nitrogen and Chdr9dd wLth LZ dm3 of liquid propylene and with 35 cm3 of ~ -a toluene solution of methylaluminoxane (corresponding to 52 of mmol Al, mean degree of oligomerization n ~ 18).
The contents were stirred at 30C for 30 minutes. In parallel, 6.0 mg tO.011 mmol~ of diphenylmethylene(9-fluorenyl)~cyclopentadienyl)zirconium dichloride, 5.0 mg (O.O10 mmol) of phenyl(methyl)methylene(9-fluorenyl)-(cyclopentadienyl) zirconium dichloride and 6,~ mg (0.014 mmol) of dLmethylmethyl~ne(g-fluorenyl)(cyclopenta-dienyl)zirconium dichloride as a mixture of ~olids were dissolved in 13.5 cm3 o~ a toluene solution o~
methylaluminoxane (20 mmol of Al). Af~er 30 minutes, the violet-xed solution was introduced into the reactor, and the polymerization system was warmed to 60C over the cour~e of S minutes by supply o F heat and kept at thi~
temperature for ~ hours.
The polymerization was terminated by addition of 1 mol vf C2 gas. 2.3 kg of polymer product were obtained. The activity was thus 67.6 kg of PP/g of metallocene mixture x h.
VN = 272 cm3~g; N~- 212,500 g/mol; M~tM~ = 3.6;
SI = 96.8~.

Example 17 Example 16 was repeated, but, in addition to propylene :~ 25 and methylaluminoxane solution, 10 dm3(s.t.p.) of :~ hydrogen and 100 g of ethylene were additionally metered into the reactor. The polymerization temperature was 50C. Under these polymerization conditions, 2.10 kg of ~: polymer product w~re obtained, corresponding to an . 30 activity of 61.8 kg of PP/g of metallocene mi~ture x h.VN = 330 cm3/g; N~ = 205,500 glmol; M~/N~ = 3.9; 4.3% of ethylene content, SI = 96.~%.

Example 18 A dry 16 dm3 reactor was flushed with nitrogen and :: 35 charged with 10 dm3 of li~uid propylene and with 30 cm3 of a toluene solution o~ methylaluminoxane (corre6ponding to 40 mmol of Al, mean degree o~ oligomerization of the methylaluminoxane was n = 20). ~he contents ware stirred ) .
. .
~:
'~:; ; - . .
- . - .
:~

2~ 3.3 _ 23 -at 30C for 10 minutes. In parallel, 8.3 mg (0.015 mmol) of diphenylmethylene~9-fluorenyl)(cyclopentadienyl)zir-conium dichloride and 7.4 mg (O.015 mmol) of phenyl(methyl)methylene~9 fluorenyl)~cyclopentadienyl)-zirconium dichloride were dissolved in 15 cm3 of atoluene 601ution of methylaluminoxane (20 mmol of Al)~
and the ~olution wa~ metered into the reactor after lO
minutes~ The polymerization temperature was kept at 45C
for 6.5 hours. The polymeri~ation was terminated by rapidly removing excess propylene in gas form. 1.95 kg of po~ymex product were obtained, and the polymerization activity wa~ l9ol kg of PP/g of metal:Locene mixture x h.
VN - 556 cm3/g; M~ - ~27,500 g/mol; N~/N~ = 3.9; SI =
97.6%.

Example 19 A dry 16 dm3 reactor was flushed with nitrogen and charged with 24 dm3(s.t.p.) (corresponding to 1.5 bar) of ~ hydrogen, lO dm3 of liquid prop~lene and with 3Q cm3 of a `~ toluene solution of methylalu~inoxane ~corresponding to 40 mmol of Al, mean degree of oligomerization of the methylaluminoxane was n = 20). The contents were stirred at 30C for L5 minutes. In parallel, 8.0 mg (0.014 mmol) of diphenylmethylene~9 f luorenyl) (cyc lopentadienyl)zi~-conium dichloride and 8.0 mg (O.016 mmol~ o~
phenyl(methyl)methylene(9-fluoxenyl)(cylcopentadienyl)-~irconium dichloride were dissolved în 7.5 cm3 of a toluene solution of methylaluminoxane (10 mmol of Al), and the ~olution was metered into the reactor after 15 ~:: minutes. The polymerization temperature was adjusted to 60C and kept at thi~ temperature for l hour by coo:Ling.

1.30 kg of polymer product were obtained, corresponding to an activity of 81.3 k~ of PP/g of metallocene mix$ure x h.
VM = 16g cm3/g; M" = 116/800 g/mol; M~ = 3.0; SI =
g6.8%.
,~
~: ~
;~` Example 20 :; , : ~ .. . :

2 ~ 3 24 ~
The procedure was as in Example 19, but 40 dm3 (~.t.p.) (2.5 bar) of hydrogen were used and the metallocene mixture comprised 8.0 mg (0~014 mmol~ of diphenyl-methylene(g-fluorenyl)(cyclopen~adienyl)zirconium dichloride and 9.0 mg (0.021 mmol) of dLmethyl-methylene(9~fluorenyl)(cyclopentadienyl)~irconium dichloride. The polymerization temperature was 70DC. 3.23 kg of polymer produc~ were obtained, corresponding to an activity of 190.5 kg of PP/g of me~allocene mi~ture x h.
VN = 105 cm3/g; M~ = 68/600 g/mol, ~S~ = 3.0; SI = 96.0%.

Example 21 ~heprocedure wasasinExample20,butonly16 dm~ ~.t.p.~
(1 bar) of hydrogen were used, and the polym~rization temperature was 65C. 2.54 kg of polymer product were obtained, corresponding to an activity of 143.4 kg of PP/g of metallocene mixture x h.
VN = 182 cm3/g; M~ = 128,500 ~/mol; M~/~ = 3~4; SI =
g~.5%.

Example 22 The procedure was as in Example 19, but only 16 dm3 (s.t.p.) ~1 bar) of hydrogen were used. Instead of 30 cm3 of the toluene solution of methylaluminoxa~e, 20 mmol of trLmethylaluminum (as a 20% ~trength by weight solution in toluene) were introduced into t~e reactor, and the ` 25 polymerization temperature was 55C and the polymeriza~ion duration was 3 hours. 1.43 kg of polymer product were obtained, corresponding to an activity of 25.7 kg of PP/y of metallocene mixture x h.
VN = 184 cm3t~; ~ = 13D,500 g/mol, M~/~ = 3.2; SI =
97.~%.

`~';.~' ',~' . .

~; , . ,

Claims (5)

1. A process for the preparation of a syndiotactic polyolefin which has a molecular weight distribution Mw/Mn of ? 3.0 and which may be monomodal, bimodal or multimodal, by polymerization or copolymerization of an olefin of the formula RaCH=CHRb in which Ra and Rb are identical or different and are a hydrogen atom or a alkyl radical having 1 to 14 carbon atoms, or Ra and Rb, together with the atoms connecting them, can form a ring, at a temperature of from -60 to 200°C, at a pressure of from 0.5 to 100 bar, in solution, in suspension or in the gas phase, in the presence of a catalyst comprising a transition-metal com-ponent (metallocene) and an aluminoxane of the formula II

(II) for the linear type and/or of the formula III

(III) for the cyclic type, where, in the formulae II and III, the radicals R9 may be identical or different and are a C1-C6-alkyl group, a C1-C6-fluoroalkyl group, aC6-C10-aryl group, a C6-C10-fluoroaryl group or a hydro-gen, and n is an integer from 0 to 50, or, instead of the aluminoxane, comprises a mixture of an aluminoxane of the formula II and/or of the formula III with a compound AlR93, which comprises using, as the transition-metal component, at least 2 metallocenes of the formula I

(I) which are stereorigid and whose moiety formed by Zr and the substituents R1-R4 has Cs symmetry of slight-ly distorted Cs symmetry, and in which R1 and R2 are identical or different and are a hydrogen atom, a halogen atom, a C1-C10-alkyl group, a C1-C10-alkoxy group. a C6-C10-aryl group, a C6-C10-aryloxy group, a C2-C10-alkenyl group, a C7-C40-arylalkyl group, a C7-C40-alkylaryl group or a C8-C40-arylalkenyl group, R3 and R4 are different and are monocyclic or polycyclic hydrocarbon radicals which can form a sandwich structure together with the central atom Zr, R5 is =BR6, =AlR6, -Ge-, -Sn-, -O-, -S-, =SO, =SO2, =NR6, =CO, =PR6 or =P(O)R6, where R6,R7 and R8 are identical or different and are a hydrogen atom, a halogen atom, a C1-C10-alkyl group, a C1-C10-fluoroalkyl group, a C6-C10-fluoroaryl group, a C6-C10-aryl 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 R6 and R7 or R6 and R8, together with the atoms connecting them, in each case form a ring, and M1 is silicon, germanium or tin.

2. The process as claimed in claim 1, wherein, in the formula I, the substituents R1 and R2 are chlorine.

3. The process as claimed in claim 1 or 2, wherein the metallocenes of the formula I are (aryl-alkylidene)(9-fluorenyl)(cyclopentadienyl)zirconium dichloride, (diarylmethylene)(g-fluorenyl)(cyclo-pentadienyl)zirconium dichloride and/or (dialkyl-methylene)(9-fluorenyl)(cyclopentadienyl)zirconium dichloride.

4. The process as claimed in one or more of claims 1 to 3, wherein the metallocenes of the formula I are (methyl(phenyl)methylene)(9-fluorenyl)(cyclo-pentadienyl)zirconium dichloride, (diphenyl-methylene)(9-fluorenyl)(cyclopentadienyl)zirconium dichloride and/or (dimethylmethylene)(9-fluorenyl)-(cyclopentadienyl)zirconium dichloride.

5. The process as claimed in one or more of claims 1 to 4 wherein propylene is polymerized.