Metallocene compound and high molecular weight copolymers of...

Details Metallocene compound and high molecular weight copolymers of... Metallocene compound and high molecular weight copolymers of...

2000-03-27

2004-09-07

Choi, Ling-Siu (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S348000, C526S335000, C526S943000, C526S131000, C526S124100, C502S152000, C502S117000, C556S011000

Reexamination Certificate

active

06787618

ABSTRACT:

The present invention relates to a metallocene catalyst system for preparing high molecular weight copolymers, and also relates to high molecular weight copolymers and an economical and environmentally friendly process for their preparation.
In the copolymerization of olefins it is possible to obtain, depending on the process procedure, random copolymers having a low content of comonomers, copolymers having a random or blocked structure and a higher incorporation of comonomers than the random copolymers or copolymer rubber having a comonomer content of significantly above 20% by weight based on the total polymer. The copolymers have different properties and different contents of comonomers. Random copolymers are generally distinguished from the corresponding homopolymers by a lower crystallinity, a lower melting point and a lower hardness. A highly random chain structure is desirable for the random copolymers. The olefin copolymers known in the prior art, which are prepared with the aid of heterogeneous Ziegler catalysts, can only meet this requirement to a very limited extent.
EP-A-263 718 describes random C
2
/C
3
/C
n
terpolymers, where n>3, which are obtained by means of heterogeneous Ziegler catalysts. The C
3
content is from 97 to 86 mol %, the C
2
content from 0.5 to 6 mol % and the C
n
content (n>3) from 2 to 13 mol %. The material has good hot sealing properties but is obtained in a two-stage process using a suspension polymerization step and a gas-phase polymerization step. In order to achieve the desired antiblocking properties, a terpolymer having a high proportion of foreign monomer has to be prepared. However, bipolymers are desirable since these are easier to handle and have a more chemically uniform chain structure.
EP-A-74 194 discloses random C
2
/C
3
copolymers which are prepared by the suspension process. To obtain the desired property profile, the polymers obtained have to be degraded. A high C
2
content is necessary to temper the chemical nonuniformity of a heterogeneous catalyst system. The nonuniformity leads to a higher proportion of low molecular weight, readily soluble, high ethylene content fractions in the polymer and thus to restricted utility in the food packaging sector.
JP-A 62-212 707 discloses an ethylene-propylene copolymer having a high ethylene content and a process for its preparation. The process is carried out using ethylenebisindenylzirconium dichloride at a temperature of less than −10° C. and is thus not suitable for industrial manufacture. In addition, the activity of the catalyst is very low.
EP-A 485 822 discloses the use of metallocenes substituted in the 2 position on the indenyl ligand for preparing copolymers. EP-A-0 629 632 and EP-A-0 576 970 describe the use of metallocene substituted in the 2 and 4 positions on the indenyl ligand. It is common to these very effective systems that they enable a good random comonomer incorporation to be realized, but that they do not enable preparation of a high molecular weight copolymer if a relatively high ethylene content is simultaneously sought. Random copolymers having high ethylene contents are preferred particularly in application areas in which a high molar mass is required. This applies particularly in deep-drawing applications, blow molding and in the case of films for the packaging sector. Sealing films are particular examples. Furthermore, a low proportion of extractable material is particularly necessary in the food packaging sector. In the case of a relatively high comonomer incorporation, this can be achieved only by a copolymer molding composition having a relatively high molecular weight. Relatively high transparencies are likewise demanded, which likewise requires a relatively high comonomer content in the polymer. Good processability of such a polymer likewise necessitates higher molar masses than can be obtained at industrially relevant polymerization temperatures of from 60 to 80° C. using the known metallocenes of the prior art.
The best known metallocenes hitherto, namely representatives of a group having indenyl ligands substituted in the 2 and 4 positions, meet this molar mass target with VN values of about 300 cm
3
/g and comonomer contents of below 2% by weight, but these comonomer contents are not sufficient to meet the property profile required of good copolymers. This necessitates higher comonomer contents in which case, for the polymers which are prepared using these metallocenes, the viscosity number (VN) very rapidly drops to values of 200 cm
3
/g and is thus too low. Processability, usability and amount of low molecular weight fractions are then in a range which rules out useful application.
The deficiencies are even clearer in the case of copolymers which are described as rubbers. They contain significantly more than 20% by weight, preferably from 30 to 60% by weight, of &agr;-olefin comonomer, possibly up to 10% by weight of a third &agr;-olefin or diene. Up to now, there is no known metallocene by means of which such a polymer molding composition having a VN of above 200 cm
3
/g can be produced at industrially realistic process temperatures (>50° C.).
It is an object of the present invention to provide a catalyst component and a catalyst system for preparing high molecular weight copolymers and also provide high molecular weight copolymers and an economical and environmentally friendly process for their preparation.
The object of the present invention is achieved by a catalyst component for preparing a high molecular weight copolymer, which catalyst component is a compound of the formula I
where
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 each a hydrogen atom, a C
1
-C
10
-alkyl group, a C
1
-C
10
-alkoxy group, a C
6
-C
10
-aryl group, a C
6
-C
10
-aryloxy group, a C
2
-C
10
-alkenyl group, a C
7
-C
40
-arylalkyl group, a C
7
-C
40
-alkylaryl group, a C
8
-C
40
-arylalkenyl group, an OH group or a halogen atom,
the radicals R
3
are identical or different and are each a halogen atom, a C
1
-C
20
-hydrocarbon group such as a C
1
-C
10
-alkyl group, a C
1
-C
10
-alkenyl group, a C
6
-C
10
-aryl group or a NR
16
2
—, —SR
16
, —OSiR
16
3
, —SiR
16
3
or PR
16
2
radical, where R
16
is a halogen atom, a C
1
-C
10
-alkyl group or a C
6
-C
10
-aryl group, R
4
to R
12
are identical or different and are as defined for R
3
or two or more adjacent radicals R
4
to R
12
together with the atoms connecting them form one or more aromatic or aliphatic rings, or the radicals R
5
and R
8
or R
12
together with the atoms connecting them form an aromatic or aliphatic ring, R
4
to R
12
may also be hydrogen and one or more radicals R
8
, R
9
, R
10
, R
11
or R
12
are different from hydrogen when the radicals R
5
, R
6
and R
7
are hydrogen,
R
13
is
═BR
14
, ═AIR
14
, —Ge—, —O—, —S—, ═SO, ═SO
2
, ═NR
14
, ═CO, ═PR
14
or ═P(O)R
14
, where R
14
and R
15
are identical or different and are each a hydrogen atom, a halogen atom, a C
1
-C
10
-, in particular C
1
-C
4
-alkyl group, a C
1
-C
10
-fluoroalkyl, in particular CF
3
group, a C
6
-C
10
-, in particular C
6
-C
8
-aryl group, a C
6
-C
10
-fluoroaryl, in particular pentafluorophenyl group, a C
1
-C
10
-, in particular C
1
-C
4
-alkoxy group, in particular a methoxy group, a C
2
-C
10
-, in particular C
2
-C
4
-alkenyl group, a C
7
-C
40
-, in particular C
7
-C
10
-arylalkyl group, a C
8
-C
40
-, in particular C
8
-C
12
-arylalkenyl group, a C
7
-C
40
-, in particular C
7
-C
12
-alkylaryl group or R
14
and R
15
together with the atoms connecting them form a ring and M
2
is silicon, germanium or tin.
For compounds of the formula I it is preferred that M
1
is zirconium or hafnium.
R
1
and R
2
are preferably identical and are preferably each a C
1
-C
4
-alkyl group or a halogen atom, the radicals R
3
are preferably each a C
1
-C
4
-alkyl group.
R
4
to R
12
are identical or different and are preferably each a hydrogen atom or a C
1
-C
4
-alkyl group, a C
1
-C
4
-alkenyl group o

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