Polymerization process

Details Polymerization process Polymerization process

2001-09-17

2003-10-07

Harlan, Robert D. (Department: 1713)

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S160000, C526S161000, C526S347000, C526S943000, C502S152000, C502S155000

Reexamination Certificate

active

06630545

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to an improved solution polymerization process. In particular, the invention relates to the use of an additive with certain metal complexes to achieve improved catalyst efficiencies in the solution polymerization of olefin monomers.
Constrained geometry metal complexes and methods for their preparation are disclosed in U.S. Pat. No. 5,703,187. This publication also teaches the preparation of certain novel copolymers of ethylene and a hindered vinyl monomer, including monovinyl aromatic monomers, having a pseudo-random incorporation of the hindered vinyl monomer therein. Additional teachings of constrained geometry catalysts may be found in U.S. Pat. Nos. 5,321,106; 5,721,185, 5,374,696, 5,470,993, 5,541,349, and 5,486,632, as well as WO97/15583, and WO97/19463. Such catalysts based on a cyclopentaphenanthreneyl ring system ligand are disclosed in U.S. Pat. No. 6,150,297. It is with respect to such metal complexes that the present improvement relates.
SUMMARY OF THE INVENTION
According to the present invention there is provided an improved process for the polymerization of addition polymerizable monomers, especially C
2-20
olefin monomers or mixtures thereof, comprising contacting an olefin monomer or mixture of olefin monomers under addition polymerization conditions with a catalyst composition comprising the reaction product or admixture of:
(A) a metal complex corresponding to the formula: CpZMX
x
L
1
X′
x′
(IA);
where Cp is an anionic, polycyclic, fused ring ligand system containing at least 4 fused rings, and bonded to M by means of delocalized &pgr;-electrons;
M is titanium, zirconium or hafnium in the +2, +3 or +4 formal oxidation state;
Z is either a cyclic or noncyclic ligand group containing delocalized &pgr;-electrons, including a second polycyclic ring system group as herein previously disclosed for Cp, said Z being bonded to M by means of delocalized n-electrons and optionally covalently bonded to Cp through a divalent bridging group, or Z is a divalent moiety lacking in delocalized &pgr;-electrons that is covalently bonded to Cp and M, or such a moiety comprising one &sgr;-bond by which it is bonded to Cp, and a neutral two electron pair able to form a coordinate-covalent bond to M;
X is a monovalent anionic ligand group having up to 60 atoms other than hydrogen;
L independently each occurrence is a neutral ligating compound having up to 20 atoms;
X′ is a divalent anionic ligand group having up to 60 atoms;
x is 0, 1, 2, or 3;
l is a number from 0 to 2, and
x′ is 0 or 1,
(B) a cocatalyst able to form an active polymerization catalyst species in combination with (A); and
(C) a conjugated diene having 4 or 5 carbons, preferably 1,3-butadiene, 1,3-pentadiene, or 3-methyl-1,3-butadiene, the molar ratio of (A):(B) being from 1:10,000 to 100:1 and the molar ratio of (C) to addition polymerizable compound being from 1:100,000 to 1:4.
The conjugated diene may be added to the reaction mixture separate from the above metal complex and cocatalyst such as by including the same in the monomer mixture added to the reactor, or it may be combined with one or both (A) and (B) prior to addition of the resulting catalyst mixture to the reactor. Surprisingly, the combination of component (C) with other metal complexes does not appear to result in improved catalyst performance. In addition, the use of other unsaturated substances in place of component (C) does not result in improved catalyst efficiency. Moreover, if too much of component (C) is used in relation to other polymerizable monomers, polymer properties are adversely affected. Desirably, the quantity of component (C) used is sufficient to provide a molar ratio of (C) to addition polymerizable compounds used in the process of from 1:1,000 to 1:10.
Use of the present process is especially efficient in production of olefin homopolymers, copolymers of two or more olefins, in particular, copolymers of ethylene and a vinylaromatic monomer, such as styrene, and interpolymers of three or more polymerizable monomers over a wide range of polymerization conditions, and especially at elevated temperatures. The process is especially suited for the formation of copolymers of ethylene and vinylaromatic monomers such as styrene (ES polymers) and copolymers of ethylene, propylene and styrene (EPS polymers).
The ES polymers generated using the present catalyst possess the previously noted valuable property that they are characterized by regular, homogeneous incorporation of vinylaromatic monomer into the polymer chain, compared to conventional ES polymers in which the vinylaromatic monomer tends to be incorporated in clusters of alternating comonomers. Such polymers possess lower peak melting points and glass transition temperatures (Tg) at comparable compositions, polymer molecular weights and molecular weight distributions compared to previously known ES polymers.
The catalyst compositions may also include a support material and be used in olefin polymerization processes in a slurry or in the gas phase. The catalyst components may be prepolymerized with one or more olefin monomers in situ in a polymerization reactor or in a separate process with intermediate recovery of the prepolymerized catalyst prior to the primary polymerization process, as well.
DETAILED DESCRIPTION
All reference to the Periodic Table of the Elements herein shall refer to the Periodic Table of the Elements, published and copyrighted by CRC Press, Inc., 1999. Also, any reference to a Group or Groups shall be to the Group or Groups as reflected in this Periodic Table of the Elements using the IUPAC system for numbering groups.
Preferred Cp groups herein include cyclopentaphenanthrene- or polycyclic azulene-based ring system ligands, optionally substituted with one or more substituents selected from hydrocarbyl, silyl, germyl, halide, hydrocarbyloxy, hydrocarbylsiloxy, hydrocarbylsilylamino, di(hydrocarbyl)amino, hydrocarbyleneamino, di(hydrocarbyl)phosphino, hydrocarbylenephosphino, hydrocarbylsulfido, halo-substituted hydrocarbyl, hydrocarbyloxy-substituted hydrocarbyl, silyl-substituted hydrocarbyl, hydrocarbylsiloxy-substituted hydrocarbyl, hydrocarbylsilylamino-substituted hydrocarbyl, di(hydrocarbyl)amino-substituted hydrocarbyl, hydrocarbyleneamino-substituted hydrocarbyl, di(hydrocarbyl)phosphino-substituted hydrocarbyl, hydrocarbylenephosphino-substituted hydrocarbyl, or hydrocarbylsulfido-substituted hydrocarbyl groups, said Cp having up to 40 atoms not counting hydrogen atoms, and optionally two or more of the foregoing substituents may together form a divalent derivative, and further optionally one or more carbons of the cyclopentaphenanthrene- or polycyclic azulene-based ring system may be replaced by a nitrogen or phosphorus atom. Such cyclopentaphenanthrene- or polycyclic azulene-based ring systems occur in several isomeric arrangements of the various rings, conventionally indicated by use of an italicized letter in the name. All of the known non-equivalent isomeric forms of cyclopentaphenanthrene (indicated as the a, b, c and l forms) are suitable for use herein. Preferred cyclopentaphenanthreneyl ring system ligand are those based on cyclopenta[c]phenanthreneyl or cyclopenta[l]phenanthreneyl groups. Preferred polycyclic azulene based ligands are dihydrodibenzoazulene derivatives.
In the foregoing metal complexes Z, if not a Cp group, preferably comprises boron, or a member of Group 14 of the Periodic Table of the Elements, and also nitrogen, phosphorus, sulfur or oxygen, and has up to 30 atoms, not counting hydrogen.
Preferred metal complexes for use according to the present invention are 1H-cyclopenta[l]-phenanthreneyl metal complexes corresponding to the formula:
where M is titanium, zirconium or hafnium in the +2, +3 or +4 formal oxidation state;
R
1
independently each occurrence is hydrogen, hydrocarbyl, silyl, germyl, halide, hydrocarbyloxy, hydrocarbylsiloxy, hydrocarbylsilylamino, di(hydrocarbyl)amino, hydrocarb

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