U.S. patent application number 09/277339 was filed with the patent office on 2002-01-24 for polymeric supported catalysts for olefin polymerization.
Invention is credited to DIAS, ANTHONY J., FRECHET, JEAN M. J., ROSCOE, STEPHEN B., WALZER, JOHN F..
Application Number | 20020010079 09/277339 |
Document ID | / |
Family ID | 27367454 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020010079 |
Kind Code |
A1 |
WALZER, JOHN F. ; et
al. |
January 24, 2002 |
POLYMERIC SUPPORTED CATALYSTS FOR OLEFIN POLYMERIZATION
Abstract
The described invention provides a low fouling, high particle
density polymerization process and an olefin polymerization
cocatalyst activator composition comprising a cross-linked polymer
bead having a surface area of from about 1 to 20 m.sup.2/g to which
are bound a plurality of non-coordinating anions, where the
polymeric support comprises ligands covalently bound to the central
metal or metalloid atoms of said anions, and an effective number of
cationic species to achieve a balanced charge. The invention also
provides an olefin polymerization catalyst compositions comprising
the reaction product of a) the foregoing cocatalyst activator, and
b) an organometallic transition metal compound having ancillary
ligands, at least one labile ligand capable of abstraction by
protonation and at least one labile ligand into which an olefinic
monomer can insert for polymerization. In a preferred embodiment,
the polymeric support has a surface area of .ltoreq.10 m.sup.2/g
and is particularly suitable for use with high activity
organometallic, transition metal catalyst compounds.
Inventors: |
WALZER, JOHN F.; (SEABROOK,
TX) ; DIAS, ANTHONY J.; (HOUSTON, TX) ;
FRECHET, JEAN M. J.; (OAKLAND, CA) ; ROSCOE, STEPHEN
B.; (WOODBURY, MN) |
Correspondence
Address: |
WILLIAM G MULLER
EXXON CHEMICAL COMPANY
P O BOX 2149
BAYTOWN
TX
77522
|
Family ID: |
27367454 |
Appl. No.: |
09/277339 |
Filed: |
March 26, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60079563 |
Mar 27, 1998 |
|
|
|
60048965 |
Jun 6, 1997 |
|
|
|
Current U.S.
Class: |
502/117 ;
502/103; 502/152; 502/155; 502/159; 526/131; 526/160; 526/163 |
Current CPC
Class: |
C08F 4/65916 20130101;
C08F 4/65908 20130101; C08F 10/00 20130101; C08F 10/00 20130101;
C08F 4/65912 20130101; C08F 4/65927 20130101 |
Class at
Publication: |
502/117 ;
526/131; 526/160; 526/163; 502/103; 502/155; 502/152; 502/159 |
International
Class: |
B01J 031/00; C08F
004/02 |
Claims
We claim:
1. A supported olefin polymerization cocatalyst activator
composition comprising a cross-linked polymer bead having a surface
area of from about 1 to 20 m.sup.2/g to which are bound a plurality
of noncoordinating anions, where the polymeric support comprises
ligands covalently bound to the central metal or metalloid atoms of
said anions, and an effective number of cationic species to achieve
a balanced charge.
2. The activator composition of claim represented by the
formula:Polymer-D.sub.n-[NCA].sup.-[Z].sup.+where Polymer is a
cross-linked polymeric backbone, D is an optional group linking the
Polymer to NCA, n is 0 or 1, NCA is a compatible noncoordinating
anion derived from a Lewis acid moiety and Z is a suitable cation
that electronically charge balances NCA.
3. An olefin polymerization catalyst composition comprising the
reaction product of a) the cocatalyst activator composition of
claim 1, and b) an organometallic transition metal compound having
ancillary ligands, at least one labile ligand capable of
abstraction by protonation and at least one labile ligand into
which an olefinic monomer can insert for polymerization.
4. The catalyst composition of claim 3 wherein said organometallic
transition metal compound is a monocyclopentadienyl
ligand-containing Group 4 metal compound.
5. The catalyst composition of claim 3 wherein said organometallic
transition metal compound is a biscyclopentadienyl
ligand-containing Group 4 metal compound.
6. The catalyst composition of claim 3 wherein said organometallic
transition metal compound is a Group 4-10 metal compound other than
a monocyclopentadienyl or biscyclopentadienyl ligand-containing
Group 4 metal compound.
7. The catalyst composition of claim 3 wherein said noncoordinating
anion is one derived from a halogenated trisaryl boron or aluminum
compound.
8. The catalyst composition of claim 3 wherein said organometallic
transition metal compound has a high activity level for olefin
polymerization and said polymer bead has a surface area of
.ltoreq.10 m.sup.2/g.
9. An olefin polymerization process comprising contacting one or
more ethylenically unsaturated olefin under suitable polymerization
conditions with the catalyst composition according to claim 3.
10. The process according to claim 9 conducted under multiphase
polymerization conditions.
11. The process according to claim 9 conducted under slurry
polymerization conditions.
12. The process according to claim 9 conducted under gas phase
polymerization conditions.
13. The process according to claim 9 wherein said olefin is
selected from ethylene and C.sub.3-C.sub.8 .alpha.-olefins, and
combinations thereof.
14. The process according to claim 13 wherein said olefin is
selected from ethylene, propylene, 1-butene, 1-hexene and 1
-octene, and combinations thereof.
15. The process according to claim 14 wherein said olefin is
propylene, optionally with ethylene, and combinations thereof.
16. The process according to claim 12 wherein said olefin is
selected from ethylene and C.sub.3-C.sub.8.alpha.-olefins, and
combinations thereof.
17. The process according to claim 11 wherein said olefin is
selected from ethylene, cyclic olefins, and styrenic olefins, and
combinations thereof.
Description
RELATED APPLICATIONS
[0001] This application claims priority from earlier filed
applications 60/048,965, filed Jun. 5, 1997, and 60/079,563, filed
Mar. 27, 1998.
TECHNICAL FIELD
[0002] This invention relates to olefin polymerization with
organometallic transition metal catalysts on polymeric supports
wherein the transition metal catalysts are activated for
polymerization by an ionizing reaction and stabilized in cationic
form with a noncoordinating anion.
BACKGROUND ART
[0003] The use of ionic catalysts for olefin polymerization where
organometallic transition metal cations are stabilized in an active
polymerization state by compatible, non-coordinating 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 is suitable for olefin insertion. Since inert
supports are used industrially for insertion polymerization
processes in both of gas phase polymerization and slurry
polymerization, technology for supporting these ionic catalysts is
also known.
[0004] U.S. Pat. No. 5,427,991 describes the chemical bonding of
discrete non-coordinating anionic activators, such as described in
the earlier U.S. Pat. No. 5,198,401, to supports so as 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 core
components of inert monomeric, oligomeric, polymeric or metal oxide
supports which have been prepared so as to incorporate chemically
bound, discrete non-coordinating anions. The teaching of the
preparation of polyanionic activators from hydrocarbyl compounds
(FIGS. 1 , 5-6 ) entails a number of reactions. A typical reaction
for a polymeric core component is that of a treating with the
lithiating agent n-BuLi, or optionally lithiating a polymerizable
monomer 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).sub.3)
and subjected to an ion exchange reaction with dimethylanilinium
hydrochloride ([DMAH].sup.+[Cl].sup.-) so as to prepare a polymer
surface having covalently linked activator groups of
[DMAH].sup.+[(pfp).sub.3BP].sup.-, where P is the polymeric core
component.
[0005] In addition to the attachment of anionic complexes to
support substrates, patent literature describes the attachment of
transition metal ligand groups to polymeric supports, the ligand
groups then being reacted with transition metal compounds so as to
form organometallic compounds bound through cyclopentadienyl
ligands to polymeric supports. Such compounds can then be rendered
suitable as olefin polymerization catalysts by the use of
activating cocatalyst compounds, e.g., such as alkylalumoxanes and
phenylborates. See U.S. Pat. Nos. 4,463,135, 5,610,115 and WO
96/35726. WO 96/35726 in particular notes the use of an
acrylate-containing copolymer support having a surface area of less
than about 15 m.sup.2/g, with examples illustrating 2.1 m.sup.2/g
surface area. These catalysts are taught to be of benefit over
metal oxide supports in requiring fewer preparation steps since
polar moieties such as adsorbed water and hydroxyl groups are not
typically present on the polymeric supports. However, this
technology presents problems in that the preparation of the support
bound ligands limits ligand selection available for subsequent
bonding to the transition metal and gives rise to low reaction
product yields and undesirable byproducts, some of which may either
interfere or compete with subsequent reactions.
[0006] Also the functionalization of polymer resin beads for use
with or preparation of heterogeneous catalytic species is known.
See, e.g., Frchet, 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 1994, 89, 81, and U.S. Pat. No.
4,246,134, this patent describing polymeric carriers of macroporous
copolymers of vinyl and divinyl monomers with specific surface
areas of 30 to 700 m.sup.2/g. and the use of such for vinyl monomer
polymerization.
[0007] The use of supported or heterogeneous catalysts in gas phase
polymerization is important as a means of increasing process
efficiencies by assuring that the forming polymeric particles
achieve shape and density that improves reactor operability and
ease of handling. Ineffective catalyst supports permit the
production of polymeric fines and resulting fouling of reactor
walls or piping. This appears to be due to a number of possible
reasons, including premature support particle fragmentation due to
excessively rapid polymerization of monomer or catalyst desorption
both of which can lead to decrease in the control of
polymerization. Polymer particle size and density can be degraded
and efficiencies lost. Additionally, ionic catalysts based on
discrete non-coordinating anions provide significant industrial
advantages in reducing the amounts of cocatalyst needed and in
often providing safer and cheaper synthesis of those cocatalyst
activator compounds. These catalysts however can be highly
sensitive to polar impurities and accordingly methods of catalyst
synthesis that can reduce the production of potential interfering
byproducts are desirable.
SUMMARY OF THE INVENTION
[0008] The invention provides a low fouling, high particle density
polymerization process using a supported olefin polymerization
cocatalyst activator composition comprising a cross-linked polymer
bead having a surface area of from about 1 to 20 m.sup.2/g to which
are bound a plurality of non-coordinating anions, where the
polymeric support comprises ligands covalently bound to the central
metal or metalloid atoms of said anions, and an effective number of
cationic species to achieve a balanced charge. The invention
includes activated olefin polymerization catalysts derived as the
reaction product of said cocatalyst activator composition and an
organometallic transition metal compound having ancillary ligands,
at least one labile ligand capable of abstraction by protonation by
said cocatalyst activator composition and at least one labile
ligand into which an olefinic monomer can insert for
polymerization. In a preferred embodiment, the polymeric support
has a surface area of .ltoreq.10 m.sup.2/g and is particularly
suitable for use with high activity organometallic, transition
metal catalyst compounds.
DESCRIPTION OF THE INVENTION
[0009] The olefin polymerization cocatalyst activator composition
according to the invention is a stable polymeric supported
activator that can be washed, stored, shipped or otherwise handled
prior to introduction of the organometallic transition metal
compounds without deleterious effects on its ability to activate by
protonation those compounds and facilitate their placement
throughout the polymeric, resin supports consisting of cross-linked
polymer beads. It comprises a protonated salt functionality having
a weakly coordinating anionic complex covalently bonded to the
polymeric support, the salt functionality comprising a suitable
cation, said polymeric support being substantially nonporous as
reflected in its low surface area.
[0010] The invention polymeric, activator support can be
represented by the formula A:
Polymer-D.sub.n-[NCA].sup.-[Z].sup.+ A
[0011] where "Polymer" is a cross-linked polymeric backbone, D is
an optional group linking the Polymer to NCA, n is 0 or 1, NCA
refers to a compatible "noncoordinating anion" derived from a Lewis
acid moiety (as further defined below), and Z is a suitable cation
that electronically charge balances NCA. The linking group is a
substantially hydrocarbyl diradical (--D--) containing 1 to 30
carbon atoms, more preferably 1 to 20 carbon atoms. Also for the
purposes of this application the term "substantially hydrocarbyl"
includes radicals where up to 3 carbon atoms of --D-- may be
replaced by heteratoms selected from the group consisting of N, O,
S, P and Se, and one or more of the hydrogen radicals may be
replaced by a halide radical. Additionally one or more of the
carbon atoms may be replaced by the other Group 14 atoms Si, Ge and
Sn.
[0012] Examples of suitable linking groups --D-- are depicted in
the chemical representations below, Ph represents phenyl. 1
[0013] The polymeric support typically comprises an essentially
hydrocarbon polymeric compound, preferably of sufficiently low
surface area so as to avoid excessive monomer access to the active
catalyst sites, which sites are distributed throughout the mass of
the support by virtue of the incorporated functional groups on the
polymeric chains making up the support. The term low surface area
means a porosity of .ltoreq.20 m.sup.2/g, preferably .ltoreq.10
m.sup.2/g, as measured a single point nitrogen B.E.T. (Brunauer,
S., Emmmet, P. H., Teller, E., JACS 1938, 60, 309) and is, for
example, based upon the use of polystyrene based beads or gels.
These beads or gels are lightly cross-linked and functionalized
with noncoordinating anions. Important features of these catalyst
support compounds is insolubility in the solvents used in preparing
the supported catalysts or in its use in polymerizing monomers, the
particle size as related to effectiveness for use in fluidized bed
reactors, and overall resistance to fracture under temperature
pressure and loading requirements. However the support is designed
to be permeable to polymerizable monomers under gas phase or slurry
polymerization. Thus the support must be insoluble under normal
polymerization operating conditions. Preferably the beads are in
the form of spheres of uniform dimension and having a normal size
range between 400 and 100 US Mesh sizing (30 to 100
micrometers).
[0014] Suitable supports can be derived in the form of crosslinked
polymers and are the most preferable for this invention. Suitable,
optionally functionalized, essentially hydrocarbon polymeric
supports or carriers can be obtained commercially, e.g.,
polystyrene beads or gels, or prepared synthetically in accordance
with general knowledge in the art, see for example the Background
art above. Polymers containing substantial oxygen content,
particularly the acrylate copolymers such as disclosed in WO
96/35726, are unsuitable as polymeric supports given the oxophilic
nature of the organometallic transition metal catalyst components
described herein. Synthesis can be by copolymerization of vinyl
monomers and subsequent chemical reaction derivation that places
the appropriate functional groups on the hydrocarbon polymeric
chains making up the supports. Specific exemplification is provided
by polystyrene-divinylbenzene copolymer gels or beads. The relative
strength, resistance to fracture, is provided by the weight %
content of divinylbenzene (DVB) comonomer, commercially available
products contain from 2 to 20 wt. % DVB. The higher ranges of DVB,
e.g., 10 to 20 wt. %, provide additional strength but the resulting
additional crosslinking hinders kinetics by making the bead
resistant to the shrinking and swelling necessary to normal
polymerization operations. The crosslinking may be designed with a
gradient to control polymerization rates and mechanical properties
of the polymeric support. The effective porosity is adjustable by
selection of crosslink content. For example, DVB contents of 5 to
10 wt. % can yield restricted polymerization kinetics suitable for
high activity polymerization catalysis, DVB contents of 1 to 5 wt.
% can provide less restricted polymerization kinetics suitable for
lower activity polymerization catalysis. The term "high activity"
relates to catalyst systems capable of activities greater than
about 1.times.10.sup.7 g-polymer/mol.-transition metal
compound-atm-hr and "low activity" can be understood as below about
that amount. Additionally, polymeric supports with higher levels of
cross-linking will be less permeable to polymerizable monomers.
[0015] Thus the compounds A can be prepared from preformed
crosslinked polymer beads which can be purchased or prepared by
emulsion polymerization of suitable monomers, for example vinyl
monomers, e.g., styrene, and a crosslinking comonomer, such as
divinyl benzene. Other suitable vinyl monomers include alkyl
substituted styrene (para-methylstyrene, alpha-methylstyrene,
meta-t-butylstyrene); halogenated styrenes (p-bromostyrene
m-bromostyrene, chloromethylstyrene,
4-bromo-2,3,5,6-tetrafluorostyrene, 3,5-trifluoromethylstyrene);
trialkylstannyl-styrenes (p-trimethylstannystyrene); butadiene,
cyclic dihydrocarbylsiloxanes (hexamethylcyclotrisiloxane,
hexaphenylcyclotrisiloxane, decamethylcyclopentasiloxane,
hexa(4-bromo-2,3,5,6-tetrafluorophenyl)cyclotri-siloxane);
butadiene, acrylonitrile, ethylene, and propylene. Typically the
crosslinked polymeric beads are lithiated so as to form
benzyllithium anion structures located throughout the polymeric
matrix. Stable anionic coordination complexes can then be prepared
by reaction with the Lewis acidic, halogenated trisaryl Group 13
metal or metalloid compounds, e.g., tris(pentafluorophenyl)boron or
aluminum. See the following examples and FIG. 5 of U.S. Pat. No.
5,427,991.
[0016] Alternatively, the functionalized, crosslinked polymeric
beads can be produced by emulsion copolymerization of a monomer
which is itself a stable anionic coordination complex and a
cross-linkable comonomer. An example of a stable coordination
complex, i.e., an anionic activator moiety, capable of emulsion
copolymerization is (N,N-dimethylanilinium
1-vinyl-2,3,5,6-tetrafluorophenyltris-(perfluorophenyl)borate). For
this monomer, N,N-dimethylanilinium is Z,
1-vinyl-2,3,5,6-tetrafluorophenyl provides --D--, and
tetrafluorophenyltris(perfluorophenyl)borate) provides NCA, the
elements of formula A above.
[0017] The term noncoordinating anion as used for the invention
compounds is art recognized to mean an anion which either does not
coordinate to a suitable organometallic transition metal cation or
which is only weakly coordinated to said cation thereby remaining
sufficiently labile to be displaced by a neutral Lewis base.
"Compatible" noncoordinating anions are those which are not
degraded to neutrality when the complexes between them and the
transition metal cationic catalyst compounds are formed. Further,
the anion will not transfer an anionic substituent or fragment to
the cation so as to cause it to form a neutral four coordinate
metal compound and a neutral by-product from the anion.
Noncoordinating anions useful in accordance with this invention are
those which are compatible, stabilize the invention transition
metal cation in the sense of balancing its ionic charge, yet retain
sufficient lability to permit displacement by an olefinically
unsaturated monomer during polymerization. Additionally, the anions
useful in this invention will be of sufficient molecular size to
partially inhibit or help to prevent neutralization of the
invention transition-metal cation by Lewis bases other than the
polymerizable monomers that may be present in the polymerization
process. Suitable discrete noncoordinating anions are described in
U.S. Pat. Nos. 5,198,401, 5,278,119, 5,407,884 or in EP 0 426 637.
All documents are incorporated by reference for purposes of U.S.
patent practice.
[0018] The Lewis acidic, halogenated trisaryl Group 13 metal or
metalloid compounds that can act suitably as noncoordinating anions
when covalently bonded to the polymeric support of this invention
are strong Lewis acids (LA) with non-hydrolyzable ligands, at least
one of which is electron-withdrawing, such as those Lewis acids
known to abstract an anionic fragment from dimethyl zirconocene
(biscyclopentedienyl zirconium dimethyl) e.g., trisperfluorophenyl
boron. For example, any Group 13 element based Lewis acids having
only alkyl, halo, alkoxy, and/or amido ligands, which are readily
hydrolyzed in aqueous media, are not suitable. At least one ligand
of the Lewis acids of the invention must be sufficiently
electron-withdrawing to achieve the needed acidity, for example, as
with trisperfluorophenyl boron. Typical metal/metalloid centers for
LA will include boron, aluminum, antimony, arsenic, phosphorous and
gallium.
[0019] Most preferably LA is a neutral compound comprising a Group
13 metalloid center with a complement of ligands together
sufficiently electron-withdrawing such that the Lewis acidity is
greater than or equal to that of AlCl.sub.3. Examples include
trisperfluorophenylboron, tris(3,5-di(trifluoromethyl)phenyl)boron,
tris(di-t-butylmethylsilyl)perf- luorophenylboron, and other highly
fluorinated trisarylboron compounds. See additionally the
description of suitable ligands for the single boron compounds of
U.S. Pat. No. 5,198,401, e.g., in columns 10-11. See also the
description in U.S. Pat. No. 5,296,433 of Lewis acid compounds
comprising tris(pentafluorophenyl)borane and specific complexing
compounds and the description in WO 97/29845 of the organo-Lewis
acid perfluorobiphenylborane. All documents are incorporated by
reference for purposes of U.S. patent practice. Halogenated
aromatic radicals are preferred so as to allow for increased charge
dispersion decreasing the likelihood of boron-ligand abstraction by
the strongly Lewis acidic metallocene cation formed in the
catalytic activation of the metallocene compound by protonation.
Thus it is preferred that there be at least three halogen atoms
replacing hydrogen atoms on each of the aryl radicals, more
preferred that the aryl ligands be perhalogenated. Fluorine in the
most preferred halogen and perfluorinated compounds are most
preferred.
[0020] Typically suitable cations (Z) that charge balance said
Lewis acid derived, polymer bonded NCA can be derived from cation
precursor salts capable of an ion exchange reaction with the
functionalized polymer beads (or the functionalized,
emulsion-polymerizable monomers), and capable of consequent
electronic stabilization of the noncoordinating anionic complex.
Such include trialkyl-substituted ammonium salts such as
triethylammonium hydrochloride, tripropylammonium hydrochloride,
tri(n-butyl)ammonium hydrochloride, trimethylammonium
hydrochloride, tributylammonium hydrochloride and the like;
N,N-dialkyl anilinium salts such as N,N-dimethylanilinium
hydrochloride, N,N-2,4,6-pentamethylanilini- um hydrochloride,
N,N-methylethyl anilinium hydrochloride and the like; and dialkyl
ammonium salts such as di-(isopropyl)ammonium hydrochloride,
dicyclohexylammonium hydrochloride, di-n-butylmethylammonium
hydrochloride, and the like. Further examples of suitable ionic
precursors include those comprising a stable carbonium or silylium
ion, and a compatible anion. These include tropillium chloride,
triphenylmethylium chloride, and benzene (diazonium)chloride.
[0021] The invention olefin polymerization catalyst composition is
the product of the reaction achieved by contacting A with an
organometallic transition metal compound that is suitable for
olefin polymerization when activated by protonation with the
polymeric supported activator of the invention. This product is a
supported ionic catalyst composition having an organometallic
transition metal cation and the complementary noncoordinating
anion, this composition being dispersed in the polymeric support
matrix.
[0022] The contacting should be conducted so as to permit
permeation of the organometallic transition metal compound into the
matrix of the polymeric support and thus is preferably conducted by
treating the supported activator particles with a solution of the
organometallic transition metal compound. Suitable solvents for the
organometallic transition metal compounds may be aliphatic or
aromatic, depending upon the ligation, the chemical composition of
the support material, and the degree of crosslinking of the
support. Toluene and hexane are typical. It is particularly
desirable to use a solvent to swell the microporous support. The
temperature and pressure of the contacting can vary so long as the
reactants, solvents and the carrier are neither degraded nor
rendered unreactive. Ambient conditions are suitable. The resulting
activation by protonation and stabilization with the polymer bound
noncoordinating anion is well known, by analogy, for organometallic
transition metal compounds suitable for olefin polymerization, see
for example, U.S. Pat. Nos. 5,198,401, 5,278,119 and WO 96/04319
for descriptions of the mechanisms involved. All documents are
incorporated by reference for purposes of U.S. patent practice.
[0023] Organometallic transition metal compounds suitable as olefin
polymerization catalysts by coordination or insertion
polymerization in accordance with the invention will include the
known transition metal compounds useful in traditional
Ziegler-Natta coordination polymerization and as well the
metallocene compounds similarly known to be useful in coordination
polymerization, when such compounds are capable of catalytic
activation by the cocatalyst activators described for the
invention. These will typically include Group 4-10 transition metal
compounds where the metal is in a d0 oxidation state, that is where
the metal has its highest oxidation number, and wherein at least
one metal ligand can be abstracted by the cocatalyst activators,
particularly those ligands including hydride, alkyl and silyl.
Ligands capable of abstraction and transition metal compounds
comprising them include those described in the background art, see
for example U.S. Pat. Nos. 5,198,401 and 5,278,119. Syntheses of
these compounds is well known from the published literature.
Additionally, where the metal ligands include halogen, amido or
alkoxy moieties (for example, biscyclopentadienyl zirconium
dichloride) which are not capable of abstraction with the
activating cocatalysts of the invention, they can be converted via
known alkylation reactions with organometallic compounds such as
lithium or aluminum hydrides or alkyls, alkylalumoxanes, Grignard
reagents, etc. See also EP-A1-0 570 982 for the reaction of
organoaluminum compounds with dihalo-substituted metallocene
compounds prior to addition of activating anion compounds. All
documents are incorporated by reference for purposes of U.S. patent
practice.
[0024] Additional description of metallocene compounds which
comprise, or can be alkylated to comprise, at least one ligand
capable of abstraction to form a catalytically active transition
metal cation appear in the patent literature, for example EP-A-0
129 368, U.S. Pat. Nos. 4,871,705, 4,937,299, 5,324,800 EP-A-0 418
044, EP-A-0 591 756, WO-A-92/00333 and WO-A-94/01471. Such
metallocene compounds can be described for this invention as mono-
or biscyclopentadienyl substituted Group 4, 5, 6, 9, or 10
transition metal compounds wherein the ancillary ligands may be
themselves substituted with one or more groups and may be bridged
to each other, or may be bridged through a heteroatom to the
transition metal. The size and constituency of the ancillary
ligands and bridging elements are not critical to the preparation
of the ionic catalyst systems of the invention but should be
selected in the literature described manner to enhance the
polymerization activity and polymer characteristics being sought.
Preferably the cyclopentadienyl rings (including substituted
cyclopentadienyl-based fused ring systems, such as indenyl,
fluorenyl, azulenyl, or substituted analogs of them), when bridged
to each other, will be lower alkyl-substituted (C.sub.1-C.sub.6) in
the 2 position (without or without a similar 4-position substituent
in the fused ring systems) and may additionally comprise alkyl,
cycloalkyl, aryl, alkylaryl and or arylalkyl subtituents, the
latter as linear, branched or cyclic structures including
multi-ring structures, for example, those of U.S. Pat. Nos.
5,278,264 and 5,304,614. Such substituents should each have
essentially hydrocarbyl characteristics and will typically contain
up to 30 carbon atoms but may be hetero-atom containing with 1-5
non-hydrogen/carbon atoms, e.g., N, S, O, P, Ge, B and Si. All
documents are incorporated by reference for purposes of U.S. patent
practice.
[0025] Metallocene compounds suitable for the preparation of linear
polyethylene or ethylene-containing copolymers (where copolymer
means comprising at least two different monomers) are essentially
any of those known in the art, see again EP-A-277,004,
WO-A-92/00333 and U.S. Pat. Nos. 5,001,205, 5,198,401, 5,324,800,
5,308,816, and 5,304,614 for specific listings. Selection of
metallocene compounds for use to make isotactic or syndiotactic
polypropylene, and their syntheses, are well-known in the art,
specific reference may be made to both patent literature and
academic, see for example Journal of Organmetallic Chemistry 369,
359-370 (1989). Typically those catalysts are stereorigid
asymmetric, chiral or bridged chiral metallocenes. See, for
example, U.S. Pat. No. 4,892,851, U.S. Pat. No. 5,017,714, U.S.
Pat. No. 5,296,434, U.S. Pat. Nos. 5,278,264, WO-A-(PCT/US92/10066)
WO-A-93/19103, EP-A2-0 577 581, EP-A1-0 578 838, and academic
literature "The Influence of Aromatic Substituents on the
Polymerization Behavior of Bridged Zirconocene Catalysts", Spaleck,
W., et al, Organometallics 1994, 13, 954-963, and "ansa-Zirconocene
Polymerization Catalysts with Annelated Ring Ligands-Effects on
Catalytic Activity and Polymer Chain Lengths", Brinzinger, H., et
al, Organometallics 1994, 13, 964-970, and documents referred to
therein. Though many above are directed to catalyst systems with
alumoxane activators, the analogous metallocene compounds will be
useful with the cocatalyst activators of this invention for active
coordination catalyst systems, when the halogen, amide or alkoxy
containing ligands of the metals (where occurring) are replaced
with ligands capable of abstraction, for example, via an alkylation
reaction as described above, and another is a group into which the
ethylene group --C.dbd.C-- may insert, for example, hydride, alkyl,
or silyl. All documents are incorporated by reference for purposes
of U.S. patent practice.
[0026] Non-limiting representative metallocene compounds include
mono-cyclopentadienyl compounds such as
pentamethylcyclopentadienyltitani- um isopropoxide,
pentamethylcyclopentadienyltribenzyl titanium,
dimethylsilyltetramethylcyclopentadienyl-tert-butylamido titanium
dichloride, pentamethylcyclopentadienyl titanium trimethyl,
dimethylsilyltetramethylcyclopentadienyl-tert-butylamido zirconium
dimethyl, dimethylsilyltetramethylcyclopentadienyl-dodecylamido
hafnium dihydride,
dimethylsilyltetramethylcyclopentadienyl-dodecylamido hafnium
dimethyl, unbridged biscyclopentadienyl compounds such as
bis(1,3-butyl, methylcyclopentadienyl) zirconium dimethyl,
pentamethylcyclopentadienyl-c- yclopentadienyl zirconium dimethyl;
bridged bis-cyclopentadienyl compounds such as
dimethylsilylbis(tetrahydroindenyl) zirconium dichloride; bridged
bisindenyl compounds such as dimethylsilylbisindenyl zirconium
dichloride, dimethylsilylbisindenyl hafnium dimethyl,
dimethylsilylbis(2-methylbenzindenyl)zirconium dichloride,
dimethylsilylbis(2-methylbenzindenyl)zirconium dimethyl; and the
additional mono- and biscyclopentadienyl compounds such as those
listed and described in U.S. Pat. Nos. 5,017,714, 5,324,800 and
EP-A-0 591 756. All documents are incorporated by reference for
purposes of U. S. patent practice.
[0027] Representative traditional Ziegler-Natta transition metal
compounds include tetrabenzyl zirconium, tetra
bis(trimethylsiylmethyl)zirconium,
oxotris(trimethlsilylmethyl)vanadium, tetrabenzyl hafnium,
tetrabenzyl titanium, bis(hexamethyl disilazido)dimethyl titanium,
tris(trimethyl silyl methyl)niobium dichloride,
tris(trimethylsilylmethyl)tantalum dichloride. The important
features of such compositions for coordination polymerization are
the ligand capable of abstraction by protonation and that ligand
into which the ethylene (olefinic) group can be inserted. These
features enable the abstraction of the transition metal compound
and the concomitant formation of the ionic catalyst composition of
the invention.
[0028] Additional organometallic transition metal compounds
suitable as olefin polymerization catalysts in accordance with the
invention will be any of those Group 4-10 that can be converted by
ligand abstraction into a catalytically active cation and
stabilized in that active electronic state by a noncoordinating or
weakly coordinating anion sufficiently labile to be displaced by an
olefinically unsaturated monomer such as ethylene. Exemplary
compounds include those described in the patent literature. U.S.
Pat. No. 5,318,935 describes bridged and unbridged bisamido
transition metal catalyst compounds of Group 4 metals capable of
insertion polymerization of .alpha.-olefins. International patent
publications WO 96/23010 and WO 97/48735 describe diimine nickel
and palladium compounds suitable for ionic activation and olefin
polymerization. Transition metal polymerization catalyst systems
from Group 5-10 metals wherein the active transition metal center
is in a high oxidation state and stabilized by low coordination
number polyanionic ancillary ligand systems are described in U.S.
Pat. No. 5,502,124 and its divisional U.S. Pat. No. 5,504,049.
Bridged bis(arylamido) Group 4 compounds for olefin polymerization
are described by D. H. McConville, et al, in Organometallics 1995,
14, 5478-5480. Synthesis methods and compound characterization are
presented. Further work appearing in D. H. McConville, et al,
Macromolecules 1996, 29, 5241-5243, described the bridged
bis(arylamido) Group 4 compounds are active catalysts for
polymerization of 1-hexene. Additional transition metal compounds
suitable in accordance with the invention include those described
in co-pending U.S. patent applications Ser. No. 08/803,687 filed
Feb. 24, 1997 and published as WO 98/37109, Ser. No. 08/999,214
filed Dec. 29, 1997 and published as WO 98/37106, Ser. No.
09/042,378, filed Mar. 13, 1998 and published as WO 98/41530, Ser.
No. 08/473,693 filed Jun. 7, 1995 and published as WO 96/40805 and
U.S. Pat. No. 5,851,945. Each of these documents is incorporated by
reference for the purposes of U.S. patent practice.
[0029] When using the supported ionic catalysts of the invention,
the total catalyst system can additionally comprise one or more
scavenging compounds. The term "scavenging compounds" is meant to
include those compounds effective for removing polar impurities
from the reaction environment. Impurities can be inadvertently
introduced with any of the polymerization reaction components,
particularly with solvent, monomer and catalyst feed, and adversely
affect catalyst activity and stability. Impurities can result in
decreased, variable or even elimination of catalytic activity. The
polar impurities, or catalyst poisons include water, oxygen, metal
impurities, etc. Preferably steps are taken before provision of
such into the reaction vessel, for example by chemical treatment or
careful separation techniques after or during the synthesis or
preparation of the various components; some minor amounts of
scavenging compound can still normally be used in the
polymerization process itself.
[0030] Typically the scavenging compound will be an organometallic
compound such as the Group 13 organometallic compounds of U.S. Pat.
Nos. 5,153,157, 5,241,025 and WO-A-93/14132, WO-A-94/07927, and
that of WO-A-95/07941. Exemplary compounds include triethyl
aluminum, triethyl borane, triisobutyl aluminum, methylalumoxane,
isobutyl aluminoxane, and tri(n-octyl)aluminum. Those scavenging
compounds having bulky or C.sub.8-C.sub.20 linear hydrocarbyl
substituents covalently bound to the metal or metalloid center
being preferred to minimize adverse interaction with the active
catalyst. The amount of scavenging agent to be used with supported
transition-metal cation-non-coordinating anion pairs is minimized
during polymerization reactions to that amount effective to enhance
activity. A particularly unexpected benefit of the supported
catalysts of the invention is the exceptionally low levels, to
essentially none, of scavenger needed to neutralize impurities. The
selective permeability of the polymeric beads appears to inhibit
the approach of the polar impurities to the active catalysts.
[0031] Gas phase processes use supported catalysts and are
conducted under gas phase or multiphase conditions suitable for
ethylene homopolymers or copolymers prepared by coordination
polymerization. Illustrative examples may be found in U.S. Pat.
Nos. 4,543,399, 4,588,790, 5,028,670, 5,352,749, 5,382,638,
5,405,922, 5,422,999, 5,436,304, 5,453,471, and 5,463,999, and
International applications WO 94/28032, WO 95/07942 and WO
96/00245. Each is incorporated by reference for purposes of U.S.
patent practice. Typically the processes are conducted at
temperatures of from about 100.degree. C. to 150.degree. C.,
preferably from about 40.degree. C. to 120.degree. C., at pressures
up to about 7000 kPa, typically from about 690 kPa to 2415 kPa.
Continuous processes using fluidized beds and recycle streams as
the fluidizing medium are preferred.
[0032] Slurry polymerization processes in which the immobilized
catalyst systems of this invention may be used are typically
described as those in which the polymerization medium can be either
a liquid monomer, like propylene, or a hydrocarbon solvent or
diluent, advantageously aliphatic paraffin such as propane,
isobutane, hexane, heptane, cyclohexane, etc. or an aromatic one
such as toluene. Diluent selection may be used to control
polymerization rates, through its effect on the degree and rate of
swelling of the polymeric support beads of the invention. For
example, toluene swells crosslinked polystyrene beads more rapidly
and to a much greater degree than does isobutane. A greater degree
of swelling will increase polymerization rates. The polymerization
temperatures may be those considered low, e.g., less than
50.degree. C., preferably 0.degree. C.-30.degree. C., or may be in
a higher range, such as up to about 150.degree. C., preferably from
50.degree. C. up to about 80.degree. C., or at any ranges between
the end points indicated. Pressures can vary from about 100 to
about 700 psia (0.76-4.8 MPa. Additional description is given in
U.S. Pat. Nos. 5,274,056 and 4,182,810 and WO 94/21962 which are
incorporated by reference for purposes of U.S. patent practice.
[0033] In the process manner discussed above with the invention
catalysts described in this application, unsaturated monomers, that
is olefinically or ethylenically unsaturated monomers, may be
polymerized so as to form polymer products having molecular weights
(weight-average or M.sub.W) from about 500 to about
3.times.10.sup.6. Most typically, the polymer products will have an
M.sub.W of from about 1000 to about 1.0.times.10.sup.6. Suitable
unsaturated monomers will include ethylene, C.sub.3-C.sub.20 linear
or branched .alpha.-olefins, C.sub.4-C.sub.20 cyclic olefins,
C.sub.4-C.sub.20 non-conjugated diolefins, C.sub.4-C.sub.20
geminally disubstituted olefins, C.sub.8-C.sub.20 styrenic olefins
or C.sub.20-C.sub.100 .alpha.-olefin macromers. Preferably the
polymer products will be any of polyethylene homopolymers and
copolymers, particularly, polyethylene plastics, plastomers and
elastomers; polypropylene homopolymers and copolymers, including
atactic, syndiotactic or isotactic polypropylene; and cyclic olefin
copolymers, particularly ethylene-norbornene copolymers. An
additional unexpected benefit of using the invention capability
resides in the selective permeability of these hydrocarbyl monomers
in the polymeric bead matrix. This selective permeability allows
ratios of monomer concentrations beyond what can be achieved using
conventional supports such as silica. For example, hexene to
ethylene feed ratios in gas phase polymerizations, which would
ordinarily lead to hexene condensation under normal operating
conditions, can be achieved since the hexene readily penetrates the
polymeric bead and is available at the active site of
polymerization without regard to condensation.
INDUSTRIAL APPLICABILITY
[0034] The supported catalyst according to the invention will be
useful for industrial means of preparing addition or insertion
polymers derived from olefinically unsaturated monomers. In
particular the invention catalysts will be particularly suitable
for use in gas phase or slurry processes, such as those practiced
industrially worldwide, largely in accordance with the description
above of these processes. Such polymer manufacturing processes are
responsible for large amounts of plastic, thermoplastic elastomers
and elastomers for films, fibers, packaging, adhesive substrates
and molded articles in common use. Additionally the methodology of
the invention can be readily extended to exploit combinatorial
methods of catalyst evaluation. The polymeric supported activators
are valuable intermediates for the construction and screening of
libraries useful for optimization of new single-site catalyst
systems capable of activation by protonation.
EXAMPLES
[0035] General
[0036] Unfunctionalized polystyrene-co-divinylbenzene beads (1%
DVB, 200-400 mesh) were supplied by Biorad Laboratories (Hercules,
Calif.) and washed carefully prior to use. Cyclohexane and dioxane
were distilled from sodium benzophenone ketyl prior to use. Other
solvents and reagents were used as received. Abbreviations in these
examples include the following THF (tetrahydrofuran), Ph (phenyl),
Me (methyl), PE (polyethylene). Unfunctionalized polystyrene beads
were purified as described by Frchet in Journal of Organic
Chemistry 1976, 41 p. 3877.
EXAMPLE 1
Preparation of Ionic Activator Bead Composition
[0037] Unfunctionalized polystyrene beads (S-X1 from Biorad
Laboratories, 10.03 g) were stirred in dry air free cyclohexane
(120 mL) under Ar. Tetramethylethylenediamine (TMEDA, 10.4 mL=66
mmol) was added and then the reaction mixture was heated to
60.degree. C. A 2.6 M solution of n-butyllithium in hexane (35
mL=91 mmol) was added by syringe causing a rapid darkening of the
suspension. After four hours stirring, the reaction mixture was
cooled and filtered, yielding red/brownbeads. These were washed
with freshly distilled dioxane until no more color was extracted
(5.times.100 mL). They were then treated with a solution of
B(C.sub.6F.sub.5).sub.3 (13.188 g=25.8 mmol) in dioxane (100 mL),
leading to rapid loss of the dark red color, and left to stir in
this solution overnight. The pale brown beads were then filtered,
washed twice with dioxane, and once with dioxane/water 80/20. They
were then extracted with dioxane/water and then THF in a soxhlet
and dried under vacuum at 60.degree. C. overnight. The increase in
mass corresponds to a loading of 0.37 meq. boron/g. Elemental
analysis: Calc.(0.37 meq/g): C 82.58, H 6.22; Found C 83.34, H
6.71. These Borated beads (10.02 g) were treated with a solution of
dimethylanilinium hydrochloride (1.82 g=11.5 mmol) in degassed
dichloromethane (80 mL) and stirred for 1.5 hours at room
temperature under argon. They were then filtered and washed with
dichloromethane (five 100 mL portions) and toluene, and dried under
vacuum at 60.degree. C. overnight. Elemental analysis: Calc. (0.37
meq.) C 82.67, H 6.41, N 0.49; Found C 83.09, H 6.71, N 0.54.
EXAMPLE 2
Catalyst A Preparation
[0038] In an inert atmosphere glove box, 1.01 grams of the Ionic
Activator Beads from Example 1 with 0.34 mmol available functional
group per gram of beads (i.e., 0.34 meq) were added to a toluene
solution (60 mL) of dimethylsilylbis(h.sup.5-2-methylindenyl)
zirconium dimethyl (0.425 g, 0.975 mmol, 2.8 eq) at 25.degree. C.
under nitrogen with vigorous stirring. The reaction was stirred for
1 h, and then the supported activator was isolated by vacuum
filtration and washed with four 15 mL portions of dry, oxygen free
toluene. The supported catalyst was then dried overnight in vacuo,
yielding 0.958 g of finished catalyst (some material loss due to
transfer), with a calculated loading of 0.30 mmol of active
transition metal per gram of finished catalyst.
EXAMPLE 3
Catalyst B Preparation
[0039] Catalyst B was prepared in analogous manner to Catalyst A,
but 0.815 grams of the Ionic Activator Beads from Example 1 with
0.34 mmol available functional group per gram of beads (i.e., 0.34
meq) was reacted with
cyclopentadienyl(pentamethylcyclopentadienyl)zirconium dimethyl
(0.132 g, 0.412 mmol, 1.5 eq), yielding 0.792 g of finished
catalyst (some material loss due to transfer), with a calculated
loading of 0.31 mmol of active transition metal per gram of
finished catalyst.
EXAMPLE 4
Catalyst C Preparation
[0040] Catalyst C was prepared in analogous manner to Catalyst A,
but 1.04 grams of the Ionic Activator Beads from Example 1 with
0.34 mmol available functional group per gram of beads (i.e., 0.34
meq) was reacted with dimethylsilylbis(u.sup.5-2-methylindenyl)
zirconium dimethyl (0.223 g, 0.512 mmol, 1.5 eq) yielding 0.1.08 g
of finished catalyst (some material loss due to transfer), with a
calculated loading of 0.30 mmol of active transition metal per gram
of finished catalyst.
EXAMPLE 5
Slurry Phase Ethylene Hexene Polymerization With Catalyst A
[0041] Polymerization was performed in the slurry-phase in a
1-liter autoclave reactor equipped with a mechanical stirrer, an
external water jacket for temperature control, a septum inlet and a
regulated supply of dry nitrogen and ethylene. The reactor was
dried and degassed thoroughly at 115.degree. C. Hexane (400 cc) was
added as a diluent, 0.4 cc of a 1.25 M triisobutyl aluminum
solution in pentane was added as a scavenger, using a gas tight
syringe, and 45 mL of hexene via cannula. The reactor was charged
with 75 psig (5.17 bar) of ethylene at 40.degree. C. A 10 cc
stainless steel bomb was charged with 0.100 g of Catalyst A (bomb
loaded in inert atmosphere glove box) and affixed to the reactor
with a swagelock fitting. The catalyst was then introduced into the
reactor. The polymerization was continued for 30 minutes while
maintaining the reaction vessel within 3.degree. C. of 40.degree.
C. and 75 psig ethylene pressure (5.17 bar) by constant ethylene
flow. The reaction was stopped by rapid cooling and venting. 41.9
grams of ethylene-hexene copolymer were recovered. The polyethylene
had a weight average molecular weight of 77,900, a molecular weight
distribution of 1.4, and contained 7.5% hexene by weight. Bulk
polymerization activity was calculated by dividing the yield of
polymer by the total weight of the catalyst charge by the time in
hours and by the absolute monomer pressure in atmospheres to yield
a value of 164 g PE/g catalyst -h- atm. The specific polymerization
activity was calculated by dividing the yield of polymer by the
total number of millimoles of transition metal contained in the
catalyst charge by the time in hours and by the absolute monomer
pressure in atmospheres, yielding a value of 552 g PE/mmol catalyst
-h- atm.
EXAMPLE 6
Slurry Phase Ethylene Hexene Polymerization With Catalyst B
[0042] Polymerization was performed as described in Example 5 but
using Catalyst B and with the following process modifications:
Temperature was maintained at 60.degree. C., ethylene pressure at
150 psig (10.34 bar), and 0.200 g of catalyst was used. The
polymerization was run for 1 hour. The reaction was stopped by
rapid cooling and venting. 97.8 grams of ethylene-hexene copolymer
was recovered. Since the ethylene/hexene ratio changed appreciably
over the course of the run (28% of the hexene was consumed) no
effort was made to obtain GPC data. The polyethylene contained
7.5.2% hexene by weight. Bulk polymerization activity was
calculated by dividing the yield of polymer by the total weight of
the catalyst charge by the time in hours and by the absolute
monomer pressure in atmospheres to yield a value of 96 g PE/g
catalyst -h- atm. The specific polymerization activity was
calculated by dividing the yield of polymer by the total number of
millimoles of transition metal contained in the catalyst charge by
the time in hours and by the absolute monomer pressure in
atmospheres, yielding a value of 311 g PE/mmol catalyst -h-
atm.
EXAMPLE 7
Bulk Phase Propylene Polymerization Using Catalyst C
[0043] Polymerization was performed in the slurry-phase in a
1-liter autoclave reactor equipped with a mechanical stirrer, an
external water jacket for temperature control, a septum inlet and a
regulated supply of dry nitrogen and propylene. The reactor was
dried and degassed thoroughly at 115.degree. C. Propylene (500 mL)
was added along with 0.6 mL of a 1.25 M triisobutyl aluminum
solution in pentane as a scavenger, using a gas tight syringe. The
reactor was heated to 40.degree. C., at which point the catalyst
was added (dry) using nitrogen pressure. The temperature was
immediately brought to 70.degree. C. and maintained within
3.degree. C. of that temperature for 16 minutes. The reaction was
stopped by rapid cooling and venting. 133.4 grams of isotactic
polypropylene was recovered, which had a weight average molecular
weight of 101,000 daltons, and a molecular weight distribution of
1.9. Bulk polymerization activity was calculated by dividing the
yield of polymer by the total weight of the catalyst charge by the
time in hours to yield a value of 5000 g PP/g catalyst -h. This
example demonstrates the use of a chiral bridged metallocene to
prepare isotactic polypropylene (i-PP). Additionally, the narrow
molecular weight distribution attests to the single sited nature of
these catalysts.
[0044] In all these polymerization examples, the majority of the
product (all product isolated as beads in Examples 6 & 7, some
fouling evident in Example 5) was isolated in the form of discrete
free flowing spherical beads of high bulk density (>0.35 g/cc),
with a similar distribution of sizes to that of the starting
polystyrene beads. This suggests that each polymer bead was the
result of polymerization from an individual catalytic bead, with
essentially no particle fracture. Analysis of ethylene uptake data
indicates shows a controlled increase in uptake rate for the first
ca. 15 min of the polymerization, and this rate was essentially
maintained for at least an hour thereafter.
[0045] This application is related to copending U.S. application
Ser. No. 09/092,752 filed Jun. 5, 1998, and published as WO
98/55518. All teachings as to the polymeric beads of this
application (surface area, emulsion polymerizable monomers and
selection of slurry solvent for swelling, etc.) are applicable in
that application as adapted to the method of anion attachment
therein.
* * * * *