Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Reexamination Certificate
1998-11-02
2001-05-08
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
C502S152000, C502S158000, C526S127000, C526S131000, C526S170000, C526S943000
Reexamination Certificate
active
06228795
ABSTRACT:
TECHNICAL FIELD
This invention relates to a catalyst system comprising a substituted, bridged indenyl metallocene supported on a polymeric support wherein the metallocene is activated for polymerization by an ionizing reaction and stabilized in cationic form with a noncoordinating anion. Propylene polymers produced by these supported catalyst systems having melting points and polymer microstructures similar to propylene polymers produced using analogous unsupported catalyst systems.
BACKGROUND
The use of ionic catalysts for olefin polymerization where organometallic transition metal (i.e., metallocene) cations are stabilized in an active polymerization state by compatible, noncoordinating anions is a well-recognized field in the chemical arts. Typically such organometallic transition metal cations are the chemical derivatives of organometallic transition metal compounds having both ancillary ligands which help stabilize the compound in an active electropositive state, and labile ligands at least one of which can be abstracted to render the compound cationic and at least one of which of which is suitable for olefin insertion. Technology for supporting these ionic catalysts is also known.
U.S. Pat. No. 5,427,991 describes the chemical bonding of noncoordinating anionic activators to supports to prepare polyanionic activators that, when used with the metallocene compounds, avoid problems of catalyst desorption experienced when ionic catalysts physically adsorbed on inert supports are utilized in solution or slurry polymerization. The supports are derived from inert monomeric, oligomeric, polymeric or metal oxide support which have been modified to incorporate chemically bound, noncoordinating anions.
The preparation of polyanionic activators from hydrocarbyl compounds entails a number of reactions. A typical reaction for a polymeric core component begins with use of the lithiating agent n-BuLi, or optionally lithiating polymerizable monomers followed by polymerization of monomers into a polymeric segment to produce a polymer or cross-linked polymer having pendant hydrocarbyl lithium groups. These are subsequently treated with the bulky Lewis acid trisperfluorophenylboron (B(pfp)
3
) and subjected to an ion exchange reaction with dimethylanilinium hydrochloride ([DMAH]
+
[Cl]
−
) which results in a polymer surface having covalently linked activator groups of [DMAH]
+
[(pfp)
3
BP]
−
, where P is the polymeric core component.
Another method for attaching a noncoordinating anion activator to the support is described and detailed herein. An aminated polymer is prepared for example by treating a cross-linked polystyrene with a dimethyl amine. The polymer bound amine is then quarternized by ion transfer from [PhNMe
2
H][B(C
6
F
5
)
4
]. The resulting support has covalently linked activator groups of [PNMe
2
H][B(C
6
F
5
)
4
] where P is again the polymeric core component.
The functionalization of polymer resin beads for use with or preparation of heterogeneous catalytic species is also known. See, e.g., Fréchet, J. M. J., Farrall, M. J., “Functionalization of Crosslinked Polystyrene by Chemical Modification”,
Chemistry and Properties of Crosslinked Polymers,
59-83 (Academic Press, 1977); and Sun, L., Shariati, A., Hsu, J. C. , Bacon, D. W.,
Studies in Surface Science and Catalysis
1995, 89, 81, and U.S. Pat. No. 4,246,134 which describes polymeric carriers of macroporous copolymers of vinyl and divinyl monomers with specific surface areas of 30 to 70 m
2
/g and the use of such for vinyl monomer polymerization.
In gas phase and slurry polymerization, the use of supported or heterogeneous catalysts increases process efficiencies by assuring that the forming polymeric particles achieve a shape and density that improves reactor operability and ease of handling. However, substituted, bridged indenyl type metallocenes, supported on silica or polymer supports, have long been observed to produce polypropylenes with more regio defects and subsequently shorter meso run lengths as determined by
13
C NMR compared to polymers produced by the respective unsupported metallocenes in solution. These defects result in a decrease in the polymer melting point which is undesirable for many applications. This invention provides a means for minimizing or even eliminating the decreased stereospecificity normally observed when using these metallocenes in supported form. Consequently, the propylene polymers of this invention have fewer defects and higher melting points than those previously obtainable in commercial processes. This achievement represents a significant advantage for polymer producers and their customers.
SUMMARY OF THE INVENTION
This invention relates generally to polymerization catalyst compositions comprising the reaction product of a) a polymeric support functionalized with a protonated ammonium salt of a noncoordinating anion and b) one or more substituted, bridged indenyl metallocene compounds.
DESCRIPTION OF THE INVENTION
As used herein the term “isotactic propylene polymer” means a homopolymer, copolymer or terpolymer comprising at least 50% propylene units having at least 60% isotactic pentads according to analysis by
13
C NMR.
As used herein the term “regio defect” means the insertion of the monomer unit in the opposite direction relative to the prevailing insertion direction. With propylene as an example, with the methylene carbon labeled as 1 and the ethylene carbon labeled as 2, the misinsertion would be that of a 2,1 insertion relative to the usual 1,2 insertion.
As used herein the term “stereo defect” means the insertion of the monomer unit in the opposite chiral handedness as that of previously inserted units. Two monomer units inserted with the same handedness are said to be a meso diad. Whereas, two monomer units inserted in the opposite handedness are said to be a racemic diad. A succession of meo diads constitutes an isotactic sequence. A succession of racemic diads constitutes a syndiotactic sequence.
As used herein the term “mis-insertion” means insertions resulting in either regio or stereo defects.
The invention olefin polymerization catalyst composition is the product of the reaction achieved by contacting a suitable functionalization aromatic polymeric support according to formulas I or II with one or more substituted, bridged indenyl metallocenes which are described in more detail below. This product is as supported ionic catalyst composition having a substituted, bridged indenyl cation and a complementary noncoordinating anion, this composition being preferably homogeneously dispersed in the polymer support matrix. Additionally, without intending to being bound hereby, it is believed that there exists a dative interaction between the transition metal cation and the amine functionality of the polymeric support matrix. The strength of this interaction should depend on the Lewis acidity of the transition metal cation and especially the Lewis basicity of the amine functionality. This interaction would act to reduce any tendency of the ionic catalyst species to desorb from the polymer support matrix. It will be noted that extremely strong Lewis bases and/or Lewis bases with minimal steric bulk are known to strongly coordinate to the vacant coordination site at the cationic metal center (e.g., pyridine). In general, this means that secondary amines are preferred over primary amines.
The functionalized aromatic polymeric supports suitable for this invention comprise a protonated ammonium salt functionality covalently bound to a polymeric support material which is preferably an aromatic polymeric support material.
The nitrogen atom of the protonated ammonium salt functionality is substituted with one to three groups at least one of which links the ammonium functionality to the polymeric support as represented by formula I or II.
[Polymer-(R
1
)—N(R
2
)(R
3
)H]
+
[NCA] I
Polymer-B(pfp)
3
−
(R
1
)(R
2
)(R
3
)NH
+
&emsp
Bell Mark L.
Exxon Chemical Patents Inc.
Pasterczyk J.
Runyan Charles E.
Schmidt C. Paige
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