Method for the polymerization of olefins

Details Method for the polymerization of olefins Method for the polymerization of olefins

2001-09-28

2004-10-12

Lu, Caixia (Department: 1713)

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C502S103000, C502S162000, C502S167000, C526S165000, C526S172000

Reexamination Certificate

active

06803431

ABSTRACT:

The present invention relates to a process for the polymerization of olefins and to a catalyst system suitable for this purpose.
Catalyst systems having a uniquely defined, active center, known as single-site catalysts, are gaining increasing importance in the polymerization of olefins. These catalyst systems lead to polymers having narrow molecular weight distributions, which results in particularly favorable mechanical properties. Among these single-site catalysts, the metallocene catalysts have hitherto achieved particular industrial importance. Appropriate substitution on the cyclopentadienyl ligands of these can influence the polymer properties. However, many metallocene catalysts can be obtained only by multistage syntheses and therefore represent a considerable cost factor in olefin polymerization.
Substituted and unsubstituted triazacycloalkanes having different ring sizes have been known for a long time. Many of them can be prepared simply and inexpensively. These ligands also coordinate well to metal ions to form stable complexes of which some possess unusual chemical and physical properties. Of particular interest here is the high stability of these coordinated ligands—an important aspect in the selection of suitable ligand systems for potential polymerization-active complexes (G. J. P. Britovsek, V. C. Gibson, D. F. Wass, Angew. Chem. 1999, 111, 448-468). Thus, it is known that N,N′N″-trialkyl-1,4,7-triazacyclononanerhodium compounds (Wang and Flood, Organomet. 15, (1996), 491-498) and -chromium compounds (G. P. Stahley et al., Acta Crystall. C51, (1995), 18-20) will polymerize or oligomerize ethene. However, the polymerization rate is very low.
Introduction of donor-functionalized side chains which bind intramolecularly to the transition metal into these triazacycloalkane ligands enables the properties of the corresponding metal.complexes to be significantly altered. Thus, a change in the redox potential or the coordination behavior of further ligands has been observed as a result (T. Kaden, Topics Curr. Chem. 121, (1984), 157-179). Complexes of this type have hitherto not been used for the polymerization of olefins.
It is an object of the present invention to find a process for the polymerization of olefins which is based on a catalyst system which has good polymerization activity and is simple to prepare and to modify.
We have found that this object is achieved by a process for the polymerization of olefins, which comprises carrying out the polymerization in the presence of catalysts comprising the following components:
(A) at least one complex of a transition metal with a tridentate macrocyclic ligand which bears at least one substituent having a donor function and
(B) if desired, one or more activator compounds.
Furthermore, we have found a catalyst system comprising the following components:
a) at least one transition metal complex (A) as set forth above and
b) at least one activator compound (B).
The tridentate macrocyclic ligand can be bound to the transition metal via nitrogen, phosphorus, oxygen or sulfur. The donor function can be uncharged or anionic and contain a heteroatom of groups 15-16 of the Periodic Table (as defined in IUPAC proposal of 1985) or be a carbanion. The donor is joined to the macrocyclic ligand via a bridge, so that from 1 to 8, preferably from 1 to 3,bridge members which comprise carbon or silicon and may be substituted form the direct linkage, but not more than two silicon atoms are in each case adjacent to one another. The functional substituent can be uncharged or anionic. If it is uncharged, it can be bound coordinatively to the transition metal center M or may not coordinate. It is preferably coordinated to the metal center M. If the functional substituent is formally anionic, it is covalently bound to the metal center. The bonds can be intramolecular or intermolecular, preferably intramolecular. During the polymerization, it may also be possible for one or more of the functional substituents to bind coordinatively or covalently to the activator compound.
In one embodiment of the process of the invention, the transition metal complex (A) used is a compound of the formula I
where the variables have the following meanings:
is a transition metal of groups 3 to 12 of the Periodic Table,
B
1
-B
3
are each a divalent radical selected from the group consisting of
where
E
1
-E
6
are silicon or carbon and not more than two of E
4
-E
6
are silicon,
A
1
-A
3
are nitrogen or phosphorus,
R
1
-R
15
are hydrogen, C
1
-C
20
-alkyl, 5- to 7-membered cycloalkyl which may in turn bear a C
6
-C
10
-aryl group as substituent, C
2
-C
20
-alkenyl, C
6
-C
10
-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the aryl part, SiR
32
3
or a radical of the formula —Z—D, where the organic radicals R
1
-R
15
may be substituted by halogen(s) and any two geminal or vicinal radicals R
1
-R
15
may also be joined to form a five- or six-membered ring, and at least one of the radicals R
1
-R
15
is a radical —Z—D, where D is a functional group having the following meanings:
D is NR
16
R
17
, NR
16
, OR
16
, SR
16
, S, PR
16
R
17
, SO
3
R
16
, OC(O)R
16
, CO
2
, C(O)R
16
, C(NR
16
)R
17
, CN or a five- or six-membered heterocyclic ring system, where the radicals
R
16
-R
17
may also be joined to Z to form a five- or six-membered ring;
Z is a divalent radical selected from the group consisting of:
where
L
1
-L
6
are silicon or carbon, not more than two of L
4
-L
6
are silicon and m=0 if any two of the vicinal radicals R
20
, R
22
, R
24
, R
26
and R
28
form an aromatic ring or a double bond is formed between two adjacent L
2
-L
6
, and otherwise m=1,
X are, independently of one another, fluorine, chlorine, bromine, iodine, hydrogen, C
1
-C
10
-alkyl, C
2
-C
10
-alkenyl, C
6
-C
20
-aryl, alkylaryl having 1-10 carbon atoms in the alkyl part and 6-20 carbon atoms in the aryl part, NR
30
R
31
, OR
30
, SR
30
, SO
3
R
30
, OC(O)R
30
, CN, SCN, =O, &bgr;-diketonate, BF
4
-, PF
6
- or bulky noncoordinating anions,
R
16
-R
31
are hydrogen, C
1
-C
20
-alkyl, 5- to 7-membered cycloalkyl which may in turn bear a C
6
-C
10
-aryl group as substituent, C
2
-C
20
-alkenyl, C
6
-C
20
-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the aryl part, SiR
32
3
, where the organic radicals R
16
-R
31
may be substituted by halogen(s) and any two geminal or vicinal radicals R
16
-R
31
may also be joined to form a five- or six-membered ring,
R
32
are, independently of one another, hydrogen, C
1
-C
20
-alkyl, 5- to 7-membered cycloalkyl which may in turn bear a C
6
-C
10
-aryl group as substituent, C
2
-C
20
-alkenyl, C
6
-C
20
-aryl, alkylaryl having from 1 to 10 carbon atoms in the alkyl part and 6-20 carbon atoms in the aryl part and any two geminal radicals R
32
may also be joined to form a five- or six-membered ring,
n is a number from 1 to 4 which corresponds to the oxidation state of M or, if D is covalently bound to the metal center M, the oxida ion state of M minus the number of groups D covalently bound to M, and, furthermore, the value of n is reduced by 1 for each X=oxygen.
Preference is here given to compounds in which A
1
, A
2
and A
3
are each a nitrogen atom.
The bridges B
1
-B
3
connecting A
1
-A
3
can influence the activity and molecular weight by means of a change in the ring size. Here, B
1
-B
3
are formed by a carbon- and/or silicon-containing divalent organic radical having a chain length of from 1 to 3. B
1
-B
3
are preferably identical. Compounds in which B
1
-B
3
are either a divalent CR
4
R
5
or CR
6
R
7
-CR
8
R
9
radical can be prepared very simply and are therefore preferred. Very particular preference is given to R
4
-R
9
being hydrogen atoms.
Varying the substituents R
1
-R
15
on the tridentate macrocycle also allows various properties of the catalyst system to be altered. The number and type of the substituents can influence the accessibility of the metal atom M to the olefins to be polymerized. This makes

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