Method for producing high melting-point polyolefins

Details Method for producing high melting-point polyolefins Method for producing high melting-point polyolefins

1998-12-30

2001-02-20

Wu, David W. (Department: 1713)

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S160000, C526S943000, C526S352000, C526S348600, C502S152000

Reexamination Certificate

active

06191241

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the use of &pgr; systems or of metallocene compounds in which a transition metal with two o systems, and in particular with aromatic &pgr; systems, such as anionic cyclopentadienyl ligands (carbanions) is complexed and the two systems are bonded reversibly to one another by at least one bridge of a donor and an acceptor, as organometallic catalysts in a process for the preparation of high-melting polyolefins by homo- or copolymerization of one or more monomers from the group consisting of optionally substituted &agr;-olefins having two or more C atoms. The coordinate bond formed between the donor atom and the acceptor atom produces a positive (part) charge in the donor group and a negative (part) charge in the acceptor group:
BACKGROUND OF THE INVENTION
Metallocenes and their use as catalysts in the polymerization of olefins have been known for a long time (EP-A 129 368 and the literature cited therein). It is furthermore known from EP-A '368 that metallocenes in combination with aluminum-alkyl/water as cocatalysts are active systems for the polymerization of ethylene (thus, for example, methylaluminoxane=MAO is formed from 1 mol of trimethylaluminum and 1 mol of water. Other stoichiometric ratios have also already been used successfully (WO 94/20506)). Metallocene in which the cyclopentadienyl skeletons are linked to one another covalently via a bridge are also already known. An example of the numerous patents and applications in this field which may be mentioned is EP-A 704 461, in which the linkage group mentioned therein is a (substituted) methylene group or ethylene group, a silylene group, a substituted silylene group, a substituted germylene group or a substituted phosphine group. The bridged metallocenes are also envisaged as polymerization catalysts for olefins in EP '461. In spite of the numerous patents and applications in this field, there continues to be a demand for improved catalysts which are distinguished by a high activity, so that the amount of catalyst remaining in the polymer can be set to a low level, and which are suitable for the polymerization and copolymerization of olefins.
SUMMARY OF THE INVENTION
It has now been found that particularly advantageous catalysts can be prepared from bridged X complex compounds, and in particular from metallocene compounds, in which the bridging of the two &pgr; systems is established by one, two or three reversible donor-acceptor bonds, in which in each case a coordinate or so-called dative bond which is overlapped at least formally by an ionic bond forms between the donor atom and the acceptor atom, and in which one of the donor or acceptor atoms can be part of the particular associated &pgr; system. The reversibility of the donor-acceptor bond also allows, in addition to the bridged state identified, by the arrow between D and A, the non-bridged state in which the two &pgr; systems can rotate against one another, for example through an angle of 360°, as a result of their inherent rotational energy, without the integrity of the metal complex being surrendered. When the rotation is complete, the donor-acceptor bond “snaps in” again. If several donors and/or acceptors are present, such “snapping in” can already take place after angles of less than 360° have been passed through. &pgr; systems according to the invention which are to be employed, for example metallocenes, can therefore be represented by just a double arrow and the formula parts (Ia) and (Ib) or (XIIIa) and (XIIIb) to include both states.
DETAILED DESCRIPTION OF THE INVENTION
The invention accordingly relates to a process for the preparation of high-melting polyolefins by homo- or copolymerization of one or more monomers from the group consisting of optionally substituted &agr;-olefins having 2 or more C atoms in the presence of organometallic catalysts which can be activated by cocatalysts, which comprises employing as the organometallic catalysts metallocene compounds of the formula
in which
CpI and CpII are two identical or different carbanions having a cyclopentadienyl-containing structure, in which one to all the H atoms can be replaced by identical or different radicals from the group consisting of linear or branched C
1
-C
20
-alkyl, which can be monosubstituted to completely substituted by halogen, mono- to trisubstituted by phenyl or mono- to trisubstituted by vinyl, C
6
-C
12
-aryl, halogenoaryl having 6 to 12 C atoms, organometallic substituents, such as silyl, trimethylsilyl or ferrocenyl, and 1 or 2 can be replaced by D and A,
D denotes a donor atom, which can additionally carry substituents and has at least one free electron pair in its particular bond state,
A denotes an acceptor atom, which can additionally carry substituents and has an electron pair gap in its particular bond state,
where D and A are linked by a reversible coordinate bond such that the donor group assumes a positive (part) charge and the acceptor group assumes a negative (part) charge,
M represents a transition metal of sub-group III, IV, V or VI of the Periodic Table of the Elements (Mendeleev), including the lanthanides and actinides,
X denotes one anion equivalent and
n denotes the number zero, one, two, three or four, depending on the charge of M,
or &pgr; complex compounds, and in particular metallocene compounds of the formula
 in which
&pgr;I and &pgr;II represent different charged or electrically neutral &pgr; systems which can be fused with one or two unsaturated or saturated five- or six-membered rings,
D denotes a donor atom, which is a substituent of &pgr;I or part of the &pgr; system of &pgr;I and has at least one free electron pair in its particular bond state,
A denotes an acceptor atom, which is a substituent of &pgr;II or part of the &pgr; system of &pgr;II and has an electron pair gap in its particular bond state,
where D and A are linked by a reversible coordinate bond such that the donor group assumes a positive (part) charge and the acceptor group assumes a negative (part) charge, and where at least one of D and A is part of the particular associated &pgr; system,
where D and A in their turn can carry substituents,
where each &pgr; system and each fused-on ring system can contain one or more D or A or D and A and
wherein &pgr;l and &pgr;II in the non-fused or in the fused form, one to all the H atoms of the &pgr; system independently of one another can be substituted by identical or different radicals from the group consisting of linear or branched C
1
-C
20
-alkyl, which can be monosubstituted to completely substituted by halogen, mono- to tri-substituted by phenyl or mono- to trisubstituted by vinyl, C
6
-C
12
-aryl, halogenoaryl having 6 to 12 C atoms, organometallic substituents, such as silyl, trimethylsilyl or ferrocenyl, or one or two can be replaced by D and A, so that the reversible coordinate D→A bond (i) is formed between D and A, which are both parts of the particular &pgr; system or the fused-on ring system, or (ii) of which D or A is part of the &pgr; system or of the fused-on ring system and in each case the other is substituent of the non-fused &pgr; system or the fused-on ring system,
M and X have the above meaning and
n denotes the number zero, one, two, three or four, depending on the charges of M and those of &pgr;-I and &pgr;-II.
&pgr; systems according to the invention are substituted and unsubstituted ethylene, allyl, pentadienyl, benzyl, butadiene, benzene, the cyclopentadienyl anion and the species which result by replacement of at least one C atom by a heteroatom.
Among the species mentioned, the cyclic species are preferred. The nature of the coordination of such ligands (&pgr; systems) to the metal can be of the s type or of the &pgr; type.
Such metallocene compounds of the formula (I) which are to be employed according to the invention can be prepared by reacting with one another either in each case a compound of the formulae (II) and (III)
or in each case a compound of the formulae (IV) and (V)
or in each case a compound of the formulae

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