Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-01-21
2001-11-13
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...
C526S159000, C526S170000, C502S152000, C502S158000, C502S167000, C502S169000, C502S200000, C556S056000, C556S063000
Reexamination Certificate
active
06316562
ABSTRACT:
This invention relates to catalyst systems for (co)polymerization reactions, containing new metallocenes with mixed substituents, the metallocenes themselves, a new method of producing metallocene compounds, and the use of metallocenamide halides for generating a catalyst system in keeping with the invention.
Polyolefin plastics have been part and parcel of our modern society ever since the discoveries of Ziegler and Natta were implemented industrially. By skillful choice of different monomers, materials can be produced which contrast with each other primarily in their different properties. The use of single-site catalysts allowed great progress to be made in obtaining further improved polymers and understanding polymerization reactions at molecular level. Combined with a co-catalyst, these polymerization initiators, also known generally as metallocenes, are highly active starters in the linking of monomers to form chains, and because of their uniform chemical and structural characteristics, guarantee a given, defined polymer or copolymer structure.
The synthetic pathway to these catalysts thus plays, so to speak, a key role, and now that chemical research has been carried out in this field with increasing intensity for some 15 years now, there are now many publications and patents describing such syntheses.
The use of metallocene dichlorides A to generate active catalyst systems, eg, with methylaluminoxan (MAO), is prior art. Strictly speaking, the metallocene dichloride is only a catalyst precursor.
The corresponding metallocene diamides B (X=NMe
2
), by contrast, have so far not been used successfully in (co)polymerization reactions. In both the formulas A and B, L stands for metallocene ligand.
Even if the use of metallocene dichloride A already provided a means of generating an active catalyst system, there was still a need for improved catalysts which show higher activity or have other advantages compared to the catalysts known so far.
This object is established according to the invention by provision of a catalyst system for (co)polymerization reactions, which contains a metallocenamide halide with the formula (I)
in which
L is a metallocene ligand,
Hal is a halogen from the group comprising F, Cl, Br and I,
M is a metal from group III, IV or V of the periodic table or from the lanthanide series, and
R stands for identical or different, straight-chain or branched, saturated or unsaturated hydrocarbon radicals with up to 8 carbon atoms, where the amido group NR
2
can also form a heterocycle with up to 8 carbon atoms, maybe incorporating further heteroatoms, and a co-catalyst.
Within the framework of this invention, it was surprisingly found that the (co)polymerization results could be improved drastically by using metallocenamide halides of formula I in a catalyst system. After activation by MAO, eg, these show much higher activity than do metallocene dichlorides, even when only small quantities of MAO are used.
In especially preferred embodiments of the invention, the metallocenamide chlorides which have the formula 1 and are contained in the catalyst system of the invention have titanium, zirconium or hafnium as metals.
In particularly preferred metallocenamide halides of formula 1, the halogen atom is a chlorine atom.
The —NR
2
radical in formula I is an amido grouping bound covalently to the metal atom. Amine compounds which are bound datively to the central metal atom only by way of the free electron pair are not considered as amido groupings in the sense of this invention.
The metallocenamide chlorides of the invention can contain, as metallocene ligands L, all &pgr; systems known for this purpose, or suitable linked or unlinked &pgr; systems. Suitable systems are known to those versed in the art. Cyclopentadienyl (Cp), indenyl (Ind) and fluorenyl (Flu) radicals, maybe substituted, can be cited as preferred examples of such systems. There can be two individual ligands present, which are the same or different, or a ligand that is linked bivalently to M and contains two &pgr; systems, or a metallocene ligand that has one &pgr; system and is linked with M via another radical. For the invention, therefore, L
2
does not necessarily mean that 2 separate ligands have to be present, but much rather the possibility of 2 valences of M being occupied by a bivalent ligand L. Bivalent ligands of this kind can, for example, contain two identical or different &pgr; systems, for example, possibly substituted Cp, Ind or Flu, which are interbridged and each of which is bound to the metal atom. However, it is also possible for just one &pgr; ligand system to be present, to which, in turn, the radical R* is bound. The radical R* forms the second bond with the metal atom. The radical R* can have all the meanings described later for the metallocenamide halides of the invention. Suitable metallocene ligands are known to those versed in the art, and can be taken, for example, from the literature sources EP 0 495 099 and PCT/WO90/07526. Within the framework of this invention, especially preferred ligands are, for example, the dimethylsilyl(tetramethylcyclopentadienyl)tert.-butylamido grouping and the (CH
3
)
2
Si(Ind)
2
grouping, or groupings which are substituted otherwise at the &pgr; ligand.
For this invention, it is to advantage to use aluminum alkyls or boron co-catalysts, in particular methylaluminoxan MAO, together with the metallocenamide halide of formula I in the catalyst system of the invention.
In principle, the compounds of formula 1 can also be present in the catalyst system of the invention as mixtures, or as mixtures with other metallocenes, half-sandwich compounds or traditional Ziegler-Natta catalysts. As cocatalyst, furthermore, any compound is suitable which can convert the metallocenamide halide of formula 1 into a cation and stabilize it.
The catalyst systems of the invention are distinguished by being extremely active; markedly less co-catalyst is required, especially when MAO is used, than for catalysts and catalyst systems known hitherto, in particular the metallocene dichlorides or diamides.
Also subject matter of this invention are metallocenamide halides of formula I,
in which
L is a metallocene ligand,
Hal is a halogen from the group comprising F, Cl, Br and I,
M is a metal from group III, IV or V of the periodic table or from the lanthanide series, and
R stands for identical or different, straight-chain or branched, saturated or unsaturated hydrocarbon radicals with up to 8 carbon atoms, where the amido group NR
2
can also form a heterocycle with up to 8 carbon atoms, maybe incorporating further heteroatoms.
The —NR
2
radical is an amido grouping bound covalently to the metal atom. Amine compounds which are bound datively to the central metal atom only by way of the free electron pair are not considered as amido groupings in the sense of this invention.
The metallocenamide halides of the invention can be used to particular advantage as components in catalyst systems according to the invention. In this invention, the two substituents L attached to the metal can together also represent a bivalent, bridged ligand.
A bivalent, bridged ligand of this kind can be bound to the metal by way of two &pgr; ligand systems, for example; ie, it can contain, for example, two cyclopentadienyl or indenyl units, maybe. in substituted form, which are interconnected and each of which is bound to the metal atom. Alternatively, there may be just one &pgr; ligand system present, to which, in turn, a radical R* is bound, which forms the second bond with the metal atom. The radical R* can form a bridge of arbitrary make-up to the metal; once again, it is preferable within the framework of the invention if R* is a hydrocarbon chain with up to 5, or better, up to 3 atoms in the chain; the chain may, in addition, be substituted and may contain heteroatoms.
It is especially preferable if the radical R* is bound via an amido group to the metal. In another especially preferred embodiment, R* contains a silyl group, and in particular a dimethylsilyl group.
For the metallocen
Detig Andreas
Hartmann Christoph
Munck Florian
Vogel Alexander
Zeiss Werner
Cheung William K
Fulbright & Jaworski LLP
Peroxid-Chemie GmbH & Co. KG
Wu David W.
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