AU612507B2 - Propylene isoblock polymer and process for its manufacture - Google Patents

Description

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Farm COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952-69 ~LETE SPECIFICATION

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612507 Class I t. Class Application Number: Lodged: Complete Specification Lodged: Accepted- Published: Priority Reiahed Art: Name of Applicant: Ac~dress of Applicant Actual Inventor: Adaress for Service: HOECHST AKI'IENGESELLSCHAET 50 Bruningstrasse, D-6230 Frankfurt/Main 80, Federal Republic of Germany VOLKER DOLLE, JUJRGEN ROHFNANN, ANDREAS WINTER arnd MARTIN ANTBERC XXMWDTXWYEAXAX0atermark. Patent Trademark Attorneys 50 QUEEN STREET, MELBOURNE, AUSTRALIA, 3000.

Complete Specification for the~ invention entitled: PROPYLENE ISOBLOCK POLYMERAND PROCESS FOR ITS MANUFACTUR The following statement is a full description of this invention, including the best mnethnd of performing it known to us THE COMMISSIONER OF PATENTS.

Edwd. WJtelr Sons, MelloI lne.

1 HOECHST AKTIENGESELLSCHAFT Dr. DA/gm HOE 88/F 189 Description Propylene isoblock polymer and process for its manufacture The invention relates to a propylene isoblock polymer with long isotactic sequences and randomly distributed ethylene units and to a process for its manufacture.

It is known that polypropylene exists in various structural isomers: 0e~o o0 0 00 0, °o 15 highly isotactic polypropylene in whose molecular

O

chains almost all tertiary C atoms have the same configuration, °0 isotactic stereoblock PP in whose molecular chains o 0 isotactic blocks of opposite configuration alternate regularly with one another, syndiotactic polypropylene in whose molecular chains 090: every other tertiary C atom has the same configura- O 0 0 o o tion, o 00 atactic polypropylene in whose molecular chains the tertiary C atoms have a random configuration,

S

c and atactic-isotactic stereoblock PP in whose molecular chains isotactic and atactic blocks alternate with one another.

A process for the manufacture of isotactic stereoblock Spolymers is known in which propylene is polymerized with the aid of a metallocene of a metal of group IVb, Vb or VIb of the periodic table US patent 4,522,982).

This metallocene is a mono-, di- or tri-cyclopentadienyl or substituted cyclopentadienyl compound of a metal, especially titanium. An aluminoxane is used as cocatalyst.

However, the titanocenes which are preferably used do not M FAT 510 Frokuritat Authorized bignat ry ppa. Tergau i.V. Lapice 2 have sufficient heat stability in dilute solution to be usable in an industrial process. Moreover, in this process, products with longer isotactic sequences (n greater than 6) are only obtained at very low temperature Finally, the cocatalysts must be used in comparatively high concentration in order to achieve an adequate catalytic yield, so the catalyst residues contained in the polymer product have to be removed in a separate purification step.

0000 oooo 0000 0 00 0 0 0 00 0 0 0000 00 0 00 00 0 0 0 0 0 o C S C C It is further known that stereoblock polymers of 1-olefins with long isotactic sequences can be obtained at industrially favorable polymerization temperatures by means of a catalyst consisting of a metallocene compound 15 with cyclopentadienyl radicals substituted by chiral groups, and of an aluminoxane European patent application A 269987).

It is further known that stereoblock polymers of l-olefins with a broad monomodal or multimodal molecular weight distribution can be obtained when 1-olefins are polymerized using a catalyst consisting of a chiral metallocene containing bridges and of an aluminoxane European patent application A 269986). The polymers are particularly suitable for the production of transparent sheets.

It i. also known that when a catalyst based on bis-cyclopentadienyl compounds of zirconium and on an aluminoxane is used in the polymerization of propylene, only atactic polymer is obtained European patent application A 69951).

Finally, highly isotactic polypropylene can be manufactured by means of soluble stereorigid chiral zirconium compounds European patent application A 185 918).

A polymerization process has been found in which a polymer of regular molecular structure and high molecular i 3 weight is obtained in high yield at industrially favorable process temperatures.

The invention thus relates to an isoblock polymer of propylene with molecular chains containing isotactic sequences which are separated from one another in each case by one monomer unit of opposite configuration, and to 10 mol%, based on the total polymer, of randomly distributed ethylene units, and with a sequence length of 3 to 50 monomer units.

The invention further relates to a process for the manu- 0co facture of the above-mentioned isoblock polymer by the 0 .o polymerization of propylene at a temperature of -60 to o° 15 100°C and a pressure of 0.5 to 100 bar, in solution, in ooo o"oo suspension or in the gas phase, in the presence of a catalyst consisting of a metallocene and an aluminoxane, 0 owherein the metallocene is a compound of formula I: 0 0 0

R

4 R3 R c 0 MI I2 A (I

R

6

R

in which

M

1 is a metal of group IVb, Vb or VIb of the periodic table,

R

1 and R 2 are identical or different and are a hydrogen atom, a Ci-Cio-alkyl group, a Ci-Clo-alkoxy group, a Cs-Cio-aryl group, a Ce-Cio-aryloxy group, a C2-C1oalkenyl group, a CT-C4o-arylalkyl group, a 07-C40alkylaryl group, a Cs-C4o-arylalkenyl group or a halogen atom, R3, R4, R 5 and R6 are identical or different and are a hydrogen atom, a halogen atom, a Ci-Cio-alkyl group,

-NR

8 2, -SRI, -OSjr'R 8 -SivR 8 avri or -PR82, in which R5 is a halogen atom or a Ci-Cio-alkyl group, or pairs of adjacent radicals R3, R4, R5 and R8 form a ring with the C atoms to which they are bonded, and

R

7 is 000 0 00000 0 oo 00 00 0 0 00 0 R)R 9 R 9

R

9

R

9

I

2

(CR

9 RlO)m, 1M 2 -0-M1 2 M1(R lOm 2 1 10 1 R RIO Rio RIO 0 1

R

9 -0-M 2

(CR

9 Rl0) M- -SO-SO- -S0-0-SO-, BR 9

-BR

9

-BR

9

R

9

R

9 I I

-PR

9

-O-PR

9 -1 -N=P-NR 9 or -,NR, II 1 11 0 0 U 0000 G0 i-n which R9 and RIO are identical or different and are a hydrogen atom, a halogen atom, a Ci-Cio-alkyl group, a Ci-Clof luorcilkyl group, a Ce-Cic-aryl group, a Ce-Ciof luoroc,-.yl group, a Ci-Cio-alkoxy group, a 02-CIOalkenyl group, a C7-C4o--arylalkyl group, a arylalkenyl group or a C7-C4o-alkylaryl group, or R9 and RI.O f orm a ring with the atoms to which they are bonded, M2 is silicon, germanium or tin and M is zero or 1.

The iBoblock polymer according to the invention is a propylene polymer.

The molecular chains of this polymer contain isotactic sequences which are separated from one another in each case by one monomer unit of opposite configuration. The molecular chains preferably consist of isotactic sequences which are separated from one another in each case by one monomer unit of opposite configuration. The isotactic sequences have a length of 3 to 50 monomer units.

The molecular chains simultaneously contain randomly distributed ethylene units which are preferably located in the isotactic sequences and have been formed by the rearrangement of propylene during polymerization. The ethylene units can be detected by 13C NMR spectroscopy Soga et al., Makrom. Chem. Rap. Comm. f, 305-310 (1987)). They are in an amount of 0.5 to 10, preferably o o15 3 to 5 mol%, based on the total polymer.

As a consequence of this steric structure, the isoblock polymers according to the invention are amorphous or partly crystalline according to the molecular weigght and the length of the isotactic sequences. Depending on the crystallinity, the polymers are obtained as granular powders or as compact masses. The partly crystalline isoblock polymers have a low melting point by comparizon 00 with isotactic polymers. Isoblock polymers possess rubber-like properties.

The catalyst to be used for the process according to the invention consists of a metallocene compound of formula I and an aluminoxane. In formula I: R4

R

1

R

Iv.PS 6 MI is a metal of group M, Vb or VIb of the periodic table, for example titanium, zirconium, hafnium, vanadiumn, niobium, tantalum, chromium, molybdenum or tungsten, preferably zirconium or hafnium.

RI and R 2 are identical or different and are a hydrogen atom, a CI-CIo-, preferably Ci-C3-alkyl group, a C-ipreferably Ci-C3-alkoxy group, a Cs-Cio-, preferably Ce- Ce-aryl group, a Cs-Cio-, preferably Ce-Ce-aryloxy group, a C2-Calo-, preferably C2-C4-alkenyl group, a C-4preferably C7-Cio-arylalkyl group, a C7-C40-, preferably C7-C12-alkylaryl group, a CB-C40-, preferably CB-C12arylalkenyl group or a halogen atom, preferably chlorine.

R

3

R

4

R

5 and RB are identical or different, preferably dif ferent, and are a hydrogen atom, a halogen atom, preferably a fluorine, chlorine or bromine atom, a C-ipreferably Ci-C3-alkyl group, -NR82, -SR8, -0SivR 8 3r--i, -SirR 8 sr-#1 or -PR 8 2, in which RB is a halogen atom, preferably a chlorine atom, or a Ci-Cia-, preferably Ci-C3alkyl group, or pairs of adjacent radicals R3, R 4

R

5 and R6 form a ring with the C atoms to which they are bonded.

R

7 is

C

4 C I -R9(C 9 10 m I M2_ (C-R 9

RI

0

)M,

R

1 0 -SO-So-,

R

9

R

9

-PR

9 -0-PR 9

-P-O_

A t

R

9

R

9

R

9 R 9 M -2(CR 9 Ri 0 mN..

RIO RIO A1O 1O SO- O-S- ,-BR 9

ER

9

BR

9

-N=PNR

9 or -N=P-NR9-, '3 in which R9 and RIO are identical or different and are a hydrogen atom, a halogen atom, a Ci-Cio-alkyl group, preferably a C1-C4-alkyl group and especially a methyl group, a Ci-Cio-fluoroalkyl group, preferably a CF3 group, a Cs-Cio-, preferably Ce-CB-aryl group, a Ce- Cio-fluoroaryl group, preferably a hexafluorophenyl group, a Ci-Cio-, preferably C1-C4-alkoxy group, especially a iethoxy group, a C2-Cio-, preferably C2-C4alkenyl group, a C7-C 4 preferably C7-Cio-arylalkyl group, a Ca-C 4 preferably Cs-C12-arylalkenyl group or a C 7

-C

4 preferably C7-C12-alkylaryl group, or R9 and RIO form a ring together with the atoms to which they are bonded.

M2 is Si, Ge or Sn.

15 R7 is preferably =SiR9RiO-SiR9RiO-.

m is zero or 1.

The metallocenes described above can be prepared according to the following reaction scheme: 0 00 00 0 00 000 0 0 00 0 Q .4 00 00 00.- 0 00O 00 0 0) 00 00 0 S0 00 0 O 0

H

2 Ra ButylLi 4 HRaLi y R 7 X HRa R 7 RbH l12RI) ButylLi 4 HRbLi (X C, BrI, 0-Tosyl, HRa 0

R

4 Rd ,HRb 0 00 a i HRa R7 RbE 2 ButylLi LiRa R7 RbLi LiRa R 7 RbLi MIi 064W4 Ra C1

R

7 8 Ra 11 Cl RT Ml SCl kb Ra /R1 R1Li R7 I U Cl \Rb Ra I7 R 1

R

2 Li R7 z Ii S\R2 Rb It is especially preferred to use bis(indenyl)bis(dimethylsilyl)hafniumn dichloride 1) and bis(indenyl)bis- (dimethylsilyl)zirconium dichloride 2) as the metallocene compounds.

15 The activator is an aluminoxane of formula (II): 4400 oes 0s 4444a 4044 o( e R11 R 1 1 R11 Al Al- 0 A i n 11

(II)

44ct tC 4 C O 4 to 4 for the linear type and/or of formula (III): A 11- Al 0

(III)

for the cyclic type. In these formulae, R11 is a C1-Cealkyl group, preferably methyl, ethyl or isobutyl, in particular methyl, and n is an integer from 2 to 50, preferably 10 to 40. The exact structure of the aluminoxane is not certain, however, so formulae II and III are only approximate formulae.

9 The aluminoxane can be prepared in a variety of ways.

One possibility is carefully to add water to a dilute solution of an aluminum trialkyl, the aluminum trialkyl solution and the water each being introduced in small portions into a larger amount of an inert solvent and the evolution of gas being allowed to finish between successive additions.

In another process, finely powdered copper sulfate pentahydrate is suspended in toluene and, in a glass flask, aluminum trialkyl is added, under inert gas at about in an amount such that about 1 mol of CuSO4-5H20 is available for every 4 Al atoms. After slow hydrolysis o° 15 with the elimination of alkane, the reaction mixture is left for 24 to 48 hours at room temperature, during which °time it must be cooled, if necessary, to prevent the tem- .o on perature from rising above 30°C. The aluminoxane diso 0 solved in the toluene is then isolated from the copper sulfate by filtration and the solution is concentrated under vacuum. It is assumed that, in this preparative o"o process, the low-molecular aluminoxanes condense to form o 0 0o higher-molecular oligomers with the elimination of aluo o0 minum trialkyl.

Furthermore, aluminoxanes are obtained when aluminum trialkyl, preferably aluminum trimethyl, dissolved in an inert aliphatic or aromatic solvent, preferably heptane Sor toluene, is reacted, at a temperature of -20 to 100*C, with aluminum salts containing water of crystallization, preferably aluminum sulfate. The volume ratio of solvent to aluminum alkyl used is 1:1 to 50:1 preferably 5:1 and the reaction time, which can be monitored by means of the alkane eliminated, is 1 to 200 hours preferably to 40 hours.

Aluminum salts containing water of crystallization which are used in particular are those with a high content of water of crystallization. Aluminum sulfate hydrates are i ,.1 especially preferred, in particular the compounds A12(S04)3'16H 2 0 and A12(S04)3-18H20 with the especially high contents of water of crystallization of 16 and 18 mol of H20/mol of A12(S04)3 respectively.

Another variant for the preparation of aluminoxanes consists in dissolving aluminum trialkyl, preferably aluminum trimethyl, in the suspending agent, preferably in the liquid monomer or in heptane or toluene, previously placed in the polymerization kettle, and then reacting the aluminum compound with water.

There are other processes for the preparation of aluminoxanes which can be used in addition to those described oP0 2 15 above.

o 0 o 0 Before it is used in the polymerization reaction, the 0o metallocene can be preactivated with an aluminoxane of formula (II) and/or (III), which markedly increases the polymerization activity.

o0"o" The preactivation of the transition metal compound is carried out in solution, the metallocene preferably being dissolved in a solution of the aluminoxane in an inert o 0 25 hydrocarbon. An aliphatic or aromatic hydrocarbon is 0 00o suitable for this purpose. Toluene is preferably used.

0 00 o0o°o The concentration of the aluminoxane in the solution is 0 00< 00 o in the range from approx. 1% by weight to the saturation 0 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, although it is preferably used in an amount of 10-4 1 mol per mol of aluminoxane. The preactivation time is 5 minutes to 60 hours, preferably to 60 minutes. The reaction temperature is -78°C to 100°C, preferably 0 to The catalyst to be used according to the invention is employed for the polymerization of 1-olefins of the 11 formula R-CH=CH2, in which R is an alky! radical having 1 to 28 C atoms, preferably 1 to 10 C atoms, in particular one C atom, for example propylene, but-1-ene, hex-1-ene, 4-methylpent-l-ene or oct-1-ene. Propylene is especially preferred.

The polymerization is carried out in known manner in solution, in suspension or in the gas phase, continuously or batchwise, in one or more steps, at a temperature of -60 to 100 0 C, preferably 0 to 80*C. The pressure is to 100 bar. Polymerization preferably takes place in the pressure range from 5 to 60 bar, which is of particular o o interest to industry.

O 0 0 00 o 15 The metallocene compound is used in a concentration of 0o os° 10-3 to 10-7, preferably 10-4 to 10s mol of transition metal per dm 3 of solvent or per dm 3 of reactor volume.

"a"o The aluminoxane is used in a concentration of 10- 4 to 1 mol, preferably 10-3 to 10- 2 mol per dm 3 of solvent or per dm 3 of reactor volume. In principle, however, higher concentrations are also possible.

0 00 ?0 0 0"0 If the polymerization is carried out in suspension or 0 00 solution, the reaction is performed in an inert solvent oo 25 conventionally used for the Ziegler low-pressure process, for example in an aliphatic or cycloaliphatic hydrocarbon; examples of such hydrocarbons which may be men- 0°0, I tioned are butane, pentane, hexane, heptane, isooctane, cyclohexane and methylcyclohexane. It is also possible to use a naphtha or hydrogenated diesel oil fraction from which oxygen, sulfur compounds and moisture have been carefully removed. Toluene can also be used. Preferably, the monomer to be polymerized is used as the solvent or suspending agent. The molecular weight of the polymer can be regulated in known manner, hydrogen preferably being used for this purpose. The polymerization time is arbitrary since the time-dependent loss of polymerization activity shown by the catalyst system to be used according to the invention is only slight.

NqN

Y;C.

12 The process accordin, to the invention is distinguished by the fact that the zirconium and hafnium comr-'nds which are preferably used are very temperature-resistant, so they can also be used at temperatures up to 900C.

Moreover, the aluminoxanes used as cocatalysts can be added in a smaller concentration than hitherto. Finally, it is now possible to manufacture isoblock polymers at temperatures which are of interest to industry.

The following Examples will serve to illustrate the invention. The abbreviations used have the meanings given below: o o VN viscosity number in cm 3 /g, 15 Mw weight-average molecular weight in g/mol, oa- Mw/Mn molecular weight distribution determined by gel o Spermeation chromatography (GPC), o"0 o II isotacticity index determined by 1sC NMR spectroscopy, and naeo average length of the isotactic sequences.

o. Isoblock polymers can be detected and distinguished from o o0, other 1-olefin polymers by NMR spectroscopy with the aid o 00 of triple resonance analysis A. Zambelli et al., 25 Macromolecules B, 687-689 (1975)). Markoff statistics are valid for isoblock polymers if the following equation is satisfied: 2(rr)/(mr) 1 The ethylene content was determined by NMR and IR spectroscopy.

Example 1 A dry 16 dm 3 kettle was flushed with nitrogen and filled with 10 dm 3 of liquid propylene. 40 cm 3 of a toluene solution of methylaluminoxane MAO, corresponding to 26.8 mmol of Al, average degree of oligomerization n 4 were then added and the reaction mixture was stirred at 30°C for 15 minutes.

In a parallel procedure, 47.9 mg (0.088 mmol) of bis- (indenyl)bis(dimethylsilyl)zirconium dichloride were dissolved in 20 cm 3 of MAO 13.4 mmol of Al) and preactivated by standing for 15 minutes. The solution was then introduced into the kettle. The polymerization system was brought to a temperature of 70*C and then kept for 5 hours at this temperature.

1.62 kg of isoblock polymer were obtained. The activity o of the metallocene was therefore 6.8 kg of polymer/g of metallocene/h.

0 gO .so The following analytical data were determined on the Sa 0 polymer: VN 14 cmS/g, Mw 9000, Mn 4750, Mw/Mn 1.9, II 73.6%, nieo 5.8, C 4.71 rnol%.

Example 2 The procedure was analogous to that in Example 1 except that 60'C was selected as the polymerization temperature.

The polymerization time was 5 hours. 100.0 mg of metallocene compound were ut3ed. 0.87 kg of isoblock polymer was obtained. The activity of the metallocene was therefore 1.7 kg of polymer/g of metallocene/h. The following analytical data were determined on the polymer: VN 17 cm 3 Mw 10,200, Mn 5700, Mw/Mn 1.8, II 74.3%, ni.o 6.0, C 3.65 mol%.

Example 3 The procedure was analogous to that in Example 1 except that 5*°C was selected as the polymerization temperature.

The polymerization time was 25 hours. 54.8 mg of metallocene compound were used in the appropriate amount of MAO. 0.46 kg of isoblock polymer was obtained. The 14 activity of the metallocene was therefore 1.67 kg of polymer/g of metallocene/h. The following analytical data were determined on the polymer: VN 21 cm 3 Mw 11,900, Mn 6300, Mw/Mn 1.9, II 75.1%, nieo 6.4, C 2.71 mol%.

Example 4 The procedure was analogous to that in Example 1 except that 40°C was selected as the polymerization temperature.

The polymerization time was 5 hours. 44.7 mg of metallocene compound were used. 0.14 kg of isoblock polymer was obtained. The activity of the metallocene was there- 0000 0 o fore 0.63 kg of polymer'g of metallocene/h. The fol- S0 0 15 lowing analytical data were determined on the polymer: as. VN 9 cms/g, Mw 12,400, Mn 6200, Mw/Mn 2.0, II o 76.4%, n±eo 6.5, C 1.4 mol%.

00 0 0 0 Example The procedure was analogous to that in Example 1 except S°a° that 10 0 C was selected as the polymerization temperature.

04 The polymerization time was 12 hours. 180.0 mg of metallocene compound were used. 0.17 kg of isoblock polymer was obtained. The activity of the metallocene was 0.08 kg of polymer/g of metallocene/h. The following analytical data were determined on the polymer: VN 58 cms/g, Mw 48,600, Mn 23,800, Mw/Mn 2.0, II 81.C%, niso 8.4, C 0.5 mol%.

Example 6 The procedure was analogous to that in Example 1 except that bis(indenyl)bis(dimethylsilyl)hafnium dichloride, in an amount of 5.0 mg 0.013 mmol), was selected as the metallocene compound (the metallocene was dissolved in cm 3 of MAO 13.4 mmol of Al), and 40 cms of MAO 26.8 mmol of Al) were added to the liquid propylene).

The polymerization system was brought to a temperature of and then kept for 5 hours at this temperature. 0.73 kg of isobiock polymer was obtained. The activity of the metallocene was therefore 6.75 kg of polymer/g of metaliocene/h. The following analytical data were determined on the polymer: VN 59 cm 3 II 77. =7,1 ,C =2.38 mol%.

Comparative Exam.-1e 0 In an experiment analogous to Example 1, a polymer with a 0 VN of 43.5 cm 3 an Mw of 35,200 and an Mw/Mn of 2.5 was 000 obtained with rac-bis (indenyl) (dimethylsilyl) zirconium .000 0 000, 15 dichloride. The isotacticity index was 96.6% and the (a 0 length of the isotactic sequences was found to be 51.

00 00 0 0 0 o 0 to0 0 00 (0 0 00 4 0 0 00 0 a 4 I

Claims (4)

1. An isoblock polymer of propylene with molecular chains containing isotactic sequences which are separated from one another in each case by one monomer unit of opposite configuration, and 0.5 to 10 mol%, based on the total polymer, of randomly distributed ethylene units, and with a sequence length of 3 to 50 monomer units.

2. The isoblock polymer according to claim 1 with mole- cular chains consisting of isotactic sequences which are separated from one another in each case by one monomer unit of opposite configuration, and containing 0.5 to mol%, based on the total polymer, of randomly distributed ethylene units.

3. A process for the manufacture of the isoblock polymer according to claim 1 by the polymerization of propylene at a temperature of -60 to 100°C and a pressure of 0.5 to 100 bar, in solution, in suspension or in the gas phase, 4 c in the presence of a catalyst consisting of a metallocene and an aluminoxane, wherein the metallocene is a compound of formula I: RR 7 SR7(I) R6 in which 17 MI is a metal of group IVb, Vb or VIb of the periodic table, Ri and R 2 are identical or different and are a hydrogen atom, a Ci-Cio-alkyl group, a Ci-Cio-alkoxy group, a Ce-Cio-aryl group, a Cs-CIu-aryloxy group, a C2-Cio- alkenyl group, a C-v-C4o--arYlailkyl group, a C7-C40- alkylaryl group, a CB-C4o-arylalkenyl group or a halo- gen atom, R3, R4, R 5 and RB are identical or different and are a hydrogen atom, a halogen atom, a Ci-Cio-alkyl group, -NR62, -SR 8 O0SirR 8 sv+I, SR 5 rior -PR82, in j' which RB is a halogen atom or a Ci-Cio-alkyl group, or pairs of adjacent radicals R3, R4, R5 and R6 form a ring with the C atoms to which they are bonded, and Qt R 9 R 9 R"3 R 9 R 9 II I I I M 2 (CR 9 R' 0 _M 2 _M 2 _(CR 9 R 1 0 )mM 2 R 1 P. 1 0 R 1 R R C C -O-M 2 (CR 9 Rl 0 -SO-SO-, -SO-O.SO- ,-BR 9 -BR 9 -BR 9 4 R4 (4 4 44PR 9 0-PR 9 -P0-P -N=P-NR 9 or-N=P-NR9-, n I 1 o 0 0 0 in which R9 and RIO are identical or different and are a hydrogen atom, a halogen atom, a Ci-Cio-alkyl group, a Ci-Cio- fluovoalkyl group, a Ce-Cio-aryl groiap, a Ce-Cio- fluoroaryl group, a Ci-Cio-alkoxy group, a 02-CIa- alkenyl group, a 07-C4o-arylalkyl group.,, a C,,,-C4o- arylalkenyl group or a C7-C4o-alkylaryl group, or R9 and RIO form a ring with the atoms to which they are n I4* 18 bonded, M2 is silicon, germanium or tin and m is zero or 1.

4. The process according to claim 3, wherein the metal- locene is bis(indenyl)bis(dimethylsilyl)hafnium di- chloride or bis(indenyl)bis(dimnethylsilyl)zirconium di- chloride. Use of the isoblock polymer according to claim 1 for o the manufacture of polymer mixtures. S* 6. Use according to claim 5 for the manufacture of poly- 4C44 'n propylene blends. DATED this 27th day of July 1989. HOECHST AKTIENGESELLSCHAFT o4p 04 0WATERMAFK PATENT TRADEMARK ATTORNEYS 50 QUEEN STREET MELBOURNE. VIC. 3000. d 4 A 41 1 444