U.S. patent application number 10/539573 was filed with the patent office on 2006-11-02 for supported olefin polymerization catalyst.
Invention is credited to Grant Berent Jacobsen, Brian Stephen Kimberley, Sergio Mastroianni.
Application Number | 20060247397 10/539573 |
Document ID | / |
Family ID | 32524110 |
Filed Date | 2006-11-02 |
United States Patent
Application |
20060247397 |
Kind Code |
A1 |
Jacobsen; Grant Berent ; et
al. |
November 2, 2006 |
Supported olefin polymerization catalyst
Abstract
A supported catalyst system comprises (a) a dehydrated support
material, (b) a transition metal compound, and (c) an activator and
is characterised in that the support material has been pretreated
with at least two different organoaluminum compounds prior to
contact with either or both the transition metal compound or the
activator. The preferr transition metal compound is a metallocene
and the supported catalyst systems are suitable for the preparation
of polymers having broad molecular weight distributions and
improved melt strength.
Inventors: |
Jacobsen; Grant Berent;
(Bouc Bel Air, FR) ; Kimberley; Brian Stephen;
(Bouc Bel Air, FR) ; Mastroianni; Sergio;
(Martigues, FR) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER;LLP
901 NEW YORK AVENUE, NW
WASHINGTON
DC
20001-4413
US
|
Family ID: |
32524110 |
Appl. No.: |
10/539573 |
Filed: |
December 3, 2003 |
PCT Filed: |
December 3, 2003 |
PCT NO: |
PCT/GB03/05206 |
371 Date: |
June 17, 2005 |
Current U.S.
Class: |
526/127 ;
502/152; 526/126; 526/160; 526/348.5; 526/348.6; 526/901;
526/943 |
Current CPC
Class: |
C08F 210/16 20130101;
C08F 4/65908 20130101; C08F 4/6592 20130101; C08F 210/16 20130101;
C08F 4/65912 20130101; C08F 2500/04 20130101; C08F 4/65916
20130101; C08F 210/16 20130101; C08F 210/14 20130101; C08F 2500/12
20130101 |
Class at
Publication: |
526/127 ;
526/126; 526/901; 526/348.5; 526/348.6; 526/160; 526/943;
502/152 |
International
Class: |
C08F 4/44 20060101
C08F004/44 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 17, 2002 |
EP |
02358031.9 |
Claims
1. A supported catalyst composition system comprising (a) a
dehydrated support material, (b) a transition metal compound, and
(c) an activator wherein said support material has been pretreated
with at least two different organoaluminum compounds prior to
contact with either or both the transition metal compound or the
activator.
2. A supported catalyst system according to claim 1 wherein the
support is a particulated solid material.
3. A supported catalyst system according to claim 2 wherein the
support is silica.
4. A supported catalyst system according to claim 1, 2 or 3 wherein
the organoaluminium compounds are trialkylaluminium compounds.
5. A supported catalyst system according to claim 1 wherein the
organoaluminium compounds are contacted sequentially with the
support material.
6. A supported catalyst system according to claim 1 wherein the
transition metal compound is a metallocene.
7. A supported catalyst system according to claim 6 wherein the
metallocene has the formula: CpMX.sub.n wherein Cp is a single
cyclopentadienyl or substituted cyclopentadienyl group optionally
covalently bonded to M through a substituent, M is a Group VIA
metal bound in a .eta..sup.5 bonding mode to the cyclopentadienyl
or substituted cyclopentadienyl group, X each occurence is hydride
or a moiety selected from the group consisting of halo, alkyl,
aryl, aryloxy, alkoxy, alkoxyalkyl, amidoalkyl, and siloxyalkyl
having up to 20 non-hydrogen atoms and neutral Lewis base ligands
having up to 20 non-hydrogen atoms or optionally one X together
with Cp forms a metallocycle with M and n is dependent upon the
valency of the metal.
8. A supported catalyst system according to claim 6 wherein the
metallocene is represented by the general formula: ##STR3##
wherein:-- R' each occurrence is independently selected from
hydrogen, hydrocarbyl, silyl, germyl, halo, cyano, and combinations
thereof, said R' having up to 20 nonhydrogen atoms, and optionally,
two R' groups (where R' is not hydrogen, halo or cyano) together
form a divalent derivative thereof connected to adjacent positions
of the cyclopentadienyl ring to form a fused ring structure; X is a
neutral .eta..sup.4 bonded diene group having up to 30 non-hydrogen
atoms, which forms a .pi.-complex with M; Y is --O--, --S--,
--NR*--, --PR*--, M is titanium or zirconium in the +2 formal
oxidation state; Z* is SiR*.sub.2, CR*.sub.2, SiR*.sub.2SiR*.sub.2,
CR*.sub.2CR*.sub.2, CR*.dbd.CR*, CR*.sub.2SiR*.sub.2, or
GeR*.sub.2, wherein: R* each occurrence is independently hydrogen,
or a member selected from hydrocarbyl, silyl, halogenated alkyl,
halogenated aryl, and combinations thereof, said R* having up to 10
non-hydrogen atoms, and optionally, two R* groups from Z* (when R*
is not hydrogen), or an R* group from Z* and an R* group from Y
form a ring system.
9. A supported catalyst system according to claim 1 wherein the
activator is an aluminoxane or a borane.
10. A supported catalyst system according to claim 1 wherein the
activator has the formula: (L*-H).sup.+.sub.d(A.sup.d-) wherein L*
is a neutral Lewis base (L*-H).sup.+.sub.d is a Bronsted acid
A.sup.d- is a non-coordinating compatible anion having a charge of
d.sup.-, and d is an integer from 1 to 3.
11. A supported catalyst system according to claim 10 wherein the
anion comprises a boron metal.
12. A supported catalyst system according to claim 10 wherein the
activator comprises a cation and an anion and wherein the anion has
at least one substituent comprising a moiety having an active
hydrogen.
13. A supported catalyst system comprising (a) a dehydrated support
material, (b) a transition metal compound, and (c) an activator
comprising (i) an organoaluminium compound and (ii) an organoboron
compound, wherein said support material has been pretreated with at
least two different organoaluminum compounds prior to contact with
either or both the transition metal compound or the activator.
14. A supported catalyst system according to claim 13 wherein the
activator comprises a trialkylaluminium compound and a triarylboron
compound.
15. A process for the polymerisation of olefin monomers selected
from (a) ethylene, (b) propylene (c) mixtures of ethylene and
propylene and (d) mixtures of (a), (b) or (c) with one or more
other alpha-olefins, said process performed under polymerisation
conditions in the presence of a supported catalyst system as
claimed in claim 1 or 13.
16. A process for the polymerisation of ethylene or the
copolymerisation of ethylene and .alpha.-olefins having from 3 to
10 carbon atoms, said process performed under polymerisation
conditions in the present of a supported polymerisation catalyst
system as claimed in claim 1 or 13.
17. A process according to claim 15 wherein the alpha-olefin is
1-butene, 1-hexene, 4-methyl-1-pentene or 1-octene.
18. A process according to any of claim 15 performed in the
solution, slurry or gas phase.
19. A process according to any of claim 15 performed in a fluidised
bed gas phase reactor.
20. A process for the preparation of copolymers of ethylene and
alpha-olefins having (a) a melt strength (16 Mpa) in the-range 3-12
cN, and (b) a molecular weight distribution (Mw/Mn) of >2. said
process comprising contacting ethylene and one or more
alpha-olefins in the presence of a supported metallocene catalyst
system as claimed in claim 1 or 13.
21. A dehydrated catalyst support material comprising support
material that has been pretreated with at least two different
organoaluminum compounds prior to the addition of further catalyst
components.
Description
[0001] The present invention relates to supported catalysts
suitable for the polymerisation of olefins and in particular to
supported catalysts suitable for the preparation of polymers having
broad molecular weight distributions and improved melt
strengths.
[0002] In recent years there have been many advances in the
production of polyolefin copolymers due to the introduction of
transition metal compounds and in particular metallocene catalysts.
Metallocene catalysts offer the advantage of generally higher
activity than traditional Ziegler catalysts and are usually
described as catalysts which are single-site in nature. Because of
their single-site nature the polyolefin copolymers produced by
metallocene catalysts often are quite uniform in their molecular
structure. For example, in comparison to traditional Ziegler
produced materials, they have relatively narrow molecular weight
distributions (MWD) and narrow Short Chain Branching Distribution
(SCBD). Although certain properties of metallocene products are
enhanced by narrow MWD, difficulties are often encountered in the
processing of these materials into useful articles and films
relative to Ziegler produced materials. In addition, the uniform
nature of the SCBD of metallocene produced materials does not
readily permit certain structures to be obtained.
[0003] The use of these metal complex based olefin polymerisation
catalysts is now well established. Typically the metallocene
complex comprises a bis(cyclopentadienyl) zirconium complex for
example bis(cyclopentadienyl) zirconium dichloride or
bis(tetramethylcyclopentadienyl) zirconium dichloride. Examples of
such complexes may be found in EP 129368, EP 206794, and EP
260130.
[0004] In such catalyst systems the metal complex is used in the
presence of a suitable activator. The activators most suitably used
with such metallocene complexes are aluminoxanes, most suitably
methyl aluminoxane (MAO). Other suitable activators are boron
compounds, in particular perfluorinated boron compounds.
[0005] More recently complexes having a single or mono
cyclopentadienyl ring have been developed. Such complexes have been
referred to as `constrained geometry` complexes and examples of
these complexes may be found in EP 416815 or EP 420436. In such
complexes the metal atom eg. zirconium or titanium is in the
highest oxidation state.
[0006] Other complexes however have been more recently developed in
which the metal atom may be in a reduced oxidation state. Examples
of both the bis (cyclopentadienyl) and mono (cyclopentadienyl)
complexes have been described in WO 96/04290 and WO 95/00526
respectively.
[0007] The above monocyclopentadienyl metallocene complexes are
utilised for polymerisation in the presence of a cocatalyst or
activator. Typically activators are aluminoxanes, in particular
methyl aluminoxane or compounds based on boron compounds. Examples
of the latter are boranes, for example tris(pentafluorophenyl)
borane, or borates such as trialkyl-substituted ammonium
tetraphenyl- or tetrafluorophenyl-borates. Catalyst systems
incorporating such borate activators are described in EP 561479, EP
418044 and EP 551277.
[0008] When used for the gas phase polymerisation of olefins,
metallocene complexes may typically be supported for example on an
inorganic oxide such as silica. Such supports may be typically
dehydrated by calcining before use or may be pretreated with an
organoaluminium compound to passivate the surface of the
silica.
[0009] EP 495849 describes a silica supported catalyst system
produced by reacting a mixture of triisobutylaluminium and
trimethylaluminium with the water contained in an undehydrated
support.
[0010] U.S. Pat. No. 5,834,393 describes in general terms the
treatment of support materials with organomagnesium, organozinc,
organoboron or organoaluminium compounds including mixtures
thereof. The reference generally describes the use of both
dehydrated and hydrdrated supports.
[0011] WO 91/05810 describes the treatment of undehydrated silica
with mixtures of trimethylaluminium and trisisobutylaluminium to
produce silica-aluminoxane products subsequently treated with Group
IVB and/or Group VB metallocenes.
[0012] WO 97/43323 describes in example 7 the addition of
triethylaluminium to a calcined silica in the presence of a borate
activator. The resultant silica is then further treated with
trihexylaluminium.
[0013] We have now surprisingly found that when dehydrated supports
(ie. substantially free of water) are pretreated with more than one
organoaluminium compound prior to contact with any other catalyst
or cocatalyst/activator components the resultant supported
catalysts may be used to prepare polymers having broad molecular
weight distributions and improved melt strengths.
[0014] Thus according to the present invention there is provided a
supported catalyst system comprising
[0015] (a) a dehydrated support material,
[0016] (b) a transition metal compound, and
[0017] (c) an activator
characterised in that said support material has been pretreated
with at least two different organoaluminum compounds prior to
contact with either or both the transition metal compound or the
activator.
[0018] By dehydrated support material is meant support material
substantially free of water.
[0019] Preferred support materials for use in the present invention
are particulated solid support materials.
[0020] The support material may be any organic or inorganic inert
solid. However particularly porous supports such as talc, inorganic
oxides and resinous support materials such as polyolefins, which
have well-known advantages in catalysis, are preferred. Suitable
inorganic oxide materials which may be used include Group 2, 13, 14
or 15 metal oxides such as silica, alumina, silica-alumina and
mixtures thereof.
[0021] Other inorganic oxides that may be employed either alone or
in combination with the silica, alumina or silica-alumina are
magnesia, titania or zirconia. Other suitable support materials may
be employed such as finely divided polyolefins such as
polyethylene.
[0022] Suitable volume average particle sizes of the support are
from 1 to 1000 .mu.m and preferably from 10 to 100 .mu.m.
[0023] The most preferred support material for use with the
supported catalysts according to the process of the present
invention is silica.
[0024] Suitable silicas include Ineos ES70 and Davidson 948
silicas.
[0025] The support material may for example be subjected to a heat
treatment in order to reduce the water content or the hydroxyl
content of the support material. For example prior to its use the
support material may be subjected to treatment at 100.degree. C. to
1000.degree. C. and preferably at 200 to 850.degree. C. in an inert
atmosphere under reduced pressure, for example, for 5 hrs.
[0026] Most preferably the support material is contacted with the
organoaluminium compounds at room temperature in a suitable
solvent, for example hexane.
[0027] Preferred organoaluminium compounds are trialkyl aluminium
compounds containing from 1 to 20 carbons atoms in each alkyl
group. Preferred trialkylaluminium compounds are
trimethylaluminium, triethylaluminium, triisopropylaluminium and
triisobutylaluminium.
[0028] In the preferred embodiment of the present invention the
support material is contacted sequentially with the organoaluminium
compounds.
[0029] The transition metal compound may be a compound of Groups
IIIA to IIB of the Periodic Table of Elements (IUPAC Version).
Examples of such transition metal compounds are traditional Ziegler
Natta, vanadium and Phillips-type catalysts well known in the
art.
[0030] The traditional Ziegler Natta catalysts include transition
metal compounds from Groups IVA-VIA, in particular catalysts based
on titanium compounds of formula MRx where M is titanium and R is
halogen or a bydrocarbyloxy group and x is the oxidation state of
the metal. Such conventional type catalysts include TiCl.sub.4,
TiBr.sub.4, Ti(OEt).sub.3Cl, Ti(OEt).sub.2Br.sub.2 and similar.
Traditional Ziegler Natta catalysts are described in more detail in
"Ziegler-Natta Catalysts and Polymerisation" by J. Boor, Academic
Press, New York, 1979.
[0031] Vanadium based catalysts include vanadyl halides eg.
VCl.sub.4, and alkoxy halides and alkoxides such as VOCl.sub.3,
VOCl.sub.2(OBu), VCl.sub.3(OBu) and similar.
[0032] Conventional chromium catalyst compounds referred to as
Phillips type catalysts include CrO.sub.3, chromocene, silyl
chromate and similar and are described in U.S. Pat. No. 4,124,532,
U.S. Pat. No. 4,302,565.
[0033] Other conventional transition metal compounds are those
based on magnesium/titanium electron donor complexes described for
example in U.S. Pat. No. 4,302,565.
[0034] Other suitable transition metal compounds are those based on
the late transition metals (LTM) of Group VIII for example
compounds containing iron, nickel, manganese, ruthenium, cobalt or
palladium metals. Examples of such compounds are described in WO
98/27124 and WO 99/12981 and may be illustrated by
[2,6-diacetylpyridinebis(2,6-diisopropylanil)FeCl.sub.2],
2.6-diacetylpyridinebis (2,4,6-trimethylanil) FeCl.sub.2 and
[2,6-diacetylpyridinebis(2,6-diisopropylanil)CoCl.sub.2].
[0035] Other transition metal compounds include derivatives of
Group IIIA, IVA or Lanthanide metals which are in the +2, +3 or +4
formal oxidation state. Preferred compounds include metal complexes
containing from 1 to 3 anionic or neutral ligand groups which may
be cyclic or non-cyclic delocalized .pi.-bonded anionic ligand
groups. Examples of such .pi.-bonded anionic ligand groups are
conjugated or non-conjugated, cyclic or non-cyclic dienyl groups,
allyl groups, boratabenzene groups, phosphole and arene groups. By
the term .pi.-bonded is meant that the ligand group is bonded to
the metal by a sharing of electrons from a partially delocalised
.pi.-bond.
[0036] Each atom in the delocalized n-bonded group may
independently be substituted with a radical selected from the group
consisting of hydrogen, halogen, hydrocarbyl, halohydrocarbyl,
hydrocarbyl, substituted metalloid radicals wherein the metalloid
is selected from Group IVB of the Periodic Table. Included in the
term "hydrocarbyl" are C1-C20 straight, branched and cyclic alkyl
radicals, C6-C20 aromatic radicals, etc. In addition two or more
such radicals may together form a fused ring system or they may
form a metallocycle with the metal.
[0037] Examples of suitable anionic, delocalised .pi.-bonded groups
include cyclopentadienyl, indenyl, fluorenyl, tetrahydroindenyl,
tetrahydrofluorenyl, octahydrofluorenyl, etc. as well as phospboles
and boratabenzene groups.
[0038] Phospholes are anionic ligands that are phosphorus
containing analogues to the cyclopentadienyl groups. They are known
in the art and described in WO 98/50392.
[0039] The boratabenzenes are anionic ligands that are boron
containing analogues to benzene. They are known in the art and are
described in Organometallics, 14, 1, 471-480 (1995).
[0040] The preferred polymerisation catalyst of the present
invention is a bulky ligand compound also referred to as a
metallocene complex containing at least one of the aforementioned
delocalized .pi.-bonded group, in particular cyclopentadienyl
ligands. Such metallocene complexes are those based on Group IVA
metals for example titanium, zirconium and hafnium.
[0041] Metallocene complexes may be represented by the general
formula: LxMQn where L is a cyclopentadienyl ligand, M is a Group
IVA metal, Q is a leaving group and x and n are dependent upon the
oxidation state of the metal.
[0042] Typically the Group IVA metal is titanium, zirconium or
hafnium, x is either 1 or 2 and typical leaving groups include
halogen or hydrocarbyl. The cyclopentadienyl ligands may be
substituted for example by alkyl or alkenyl groups or may comprise
a fused ring system such as indenyl or fluorenyl.
[0043] Examples of suitable metallocene complexes are disclosed in
EP 129368 and EP 206794. Such complexes may be unbridged eg.
bis(cyclopentadienyl) zirconium dichloride,
bis(pentamethyl)cyclopentadienyl dichloride, or may be bridged eg.
ethylene bis(indenyl) zirconium dichloride or
dimethylsilyl(indenyl) zirconium dichloride.
[0044] Other suitable bis(cyclopentadienyl) metallocene complexes
are those bis(cyclopentadienyl) diene complexes described in WO
96/04290. Examples of such complexes are bis(cyclopentadienyl)
zirconium (2.3-dimethyl-1,3-butadiene) and ethylene bis(indenyl)
zirconium 1,4-diphenyl butadiene.
[0045] Examples of monocyclopentadienyl or substituted
monocyclopentadienyl complexes suitable for use in the present
invention are described in EP 416815, EP 418044, EP 420436 and EP
551277. Suitable complexes may be represented by the general
formula: CpMXn
[0046] wherein Cp is a single cyclopentadienyl or substituted
cyclopentadienyl group optionally covalently bonded to M through a
substituent, M is a Group VIA metal bound in a .eta..sup.5 bonding
mode to the cyclopentadienyl or substituted cyclopentadienyl group,
X each occurrence is hydride or a moiety selected from the group
consisting of halo, alkyl, aryl, aryloxy, alkoxy, alkoxyalkyl,
amidoalkyl, siloxyalkyl etc. having up to 20 non-hydrogen atoms and
neutral Lewis base ligands having up to 20 non-hydrogen atoms or
optionally one X together with Cp forms a metallocycle with M and n
is dependent upon the valency of the metal.
[0047] Particularly preferred monocyclopentadienyl complexes have
the formula: ##STR1## wherein:-- [0048] R' each occurrence is
independently selected from hydrogen, hydrocarbyl, silyl, germyl,
halo, cyano, and combinations thereof, said R' having up to 20
nonhydrogen atoms, and optionally, two R' groups (where R' is not
hydrogen, halo or cyano) together form a divalent derivative
thereof connected to adjacent positions of the cyclopentadienyl
ring to form a fused ring structure; [0049] X is hydride or a
moiety selected from the group consisting of halo, alkyl, aryl,
aryloxy, alkoxy, alkoxyalkyl, amidoalkyl, siloxyalkyl etc. having
up to 20 non-hydrogen atoms and neutral Lewis base ligands having
up to 20 non-hydrogen atoms, [0050] Y is --O--, --S--, --NR*--,
--PR*--, [0051] M is hafnium, titanium or zirconium, [0052] Z* is
SiR*.sub.2, CR*.sub.2, SiR*.sub.2SIR*.sub.2, CR*.sub.2CR*.sub.2,
CR*.dbd.CR*, CR*.sub.2SIR*.sub.2, or [0053] GeR*.sub.2,
wherein:
[0054] R* each occurrence is independently hydrogen, or a member
selected from hydrocarbyl, silyl, halogenated alkyl, halogenated
aryl, and combinations thereof, said
[0055] R* having up to 10 non-hydrogen atoms, and optionally, two
R* groups from Z* (when R* is not hydrogen), or an R* group from Z*
and an R* group from Y form a ring system,
[0056] and n is 1 or 2 depending on the valence of M.
[0057] Examples of suitable monocyclopentadienyl complexes are
(tert-butylamido)
dimethyl(tetramethyl-.eta..sup.5-cyclopentadienyl) silanetitanium
dichloride and
(2-methoxyphenylamido)dimethyl(tetramethyl-.eta..sup.5-cyclopentadienyl)
silanetitanium dichloride.
[0058] Other suitable monocyclopentadienyl complexes are those
comprising phosphinimine ligands described in WO 99/40125, WO
00/05237, WO 00/05238 and WO00/32653. A typical examples of such a
complex is cyclopentadienyl titanium [tri (tertiary butyl)
phosphinimine] dichloride.
[0059] Another type of polymerisation catalyst suitable for use in
the present invention are monocyclopentadienyl complexes comprising
heteroallyl moieties such as zirconium
(cyclopentadienyl)tris(diethylcarbamates) as described in U.S. Pat.
No. 5,527,752 and WO 99/61486.
[0060] Particularly preferred metallocene complexes for use in the
preparation of the supported catalysts of the present invention may
be represented by the general formula: ##STR2##
[0061] wherein:-- [0062] R' each occurrence is independently
selected from hydrogen, hydrocarbyl, silyl, germyl, halo, cyano,
and combinations thereof, said R' having up to 20 nonhydrogen
atoms, and optionally, two R' groups (where R' is not hydrogen,
halo or cyano) together form a divalent derivative thereof
connected to adjacent positions of the cyclopentadienyl ring to
form a fused ring structure; [0063] X is a neutral .eta..sup.4
bonded diene group having up to 30 non-hydrogen atoms, which forms
a .pi.-complex with M; [0064] Y is --O--, --S--, --NR*--, --PR*--,
[0065] M is titanium or zirconium in the +2 formal oxidation state;
[0066] Z* is SiR*.sub.2, CR*.sub.2, SiR*.sub.2SIR*.sub.2,
CR*.sub.2CR*.sub.2, CR*.dbd.CR*, CR*.sub.2SIR*.sub.2, or
GeR*.sub.2, wherein:
[0067] R* each occurrence is independently hydrogen, or a member
selected from hydrocarbyl, silyl, halogenated alkyl, halogenated
aryl, and combinations thereof, said
[0068] R* having up to 10 non-hydrogen atoms, and optionally, two
R* groups from Z* (when R* is not hydrogen), or an R* group from Z*
and an R* group from Y form a ring system.
[0069] Examples of suitable X groups include
s-trans-.eta..sup.4-1,4-diphenyl-1,3-butadiene,
s-trans-.eta..sup.4-3-methyl-1,3-pentadiene;
s-trans-.eta..sup.4-2,4-hexadiene;
s-trans-.eta..sup.4-1,3-pentadiene;
s-trans-.eta..sup.4-1,4-ditolyl-1,3-butadiene;
s-trans-.eta..sup.4-1,4-bis(trimethylsilyl)-1,3-butadiene;
s-cis-.eta..sup.4-3-methyl-1,3-pentadiene;
s-cis-.eta..sup.4-1,4-dibenzyl-1,3-butadiene;
s-cis-.eta..sup.4-1,3-pentadiene;
s-cis-.eta..sup.4-1,4-bis(trimethylsilyl)-1,3-butadiene, said s-cis
diene group forming a .pi.-complex as defined herein with the
metal.
[0070] Most preferably R' is hydrogen, methyl, ethyl, propyl,
butyl, pentyl, hexyl, benzyl, or phenyl or 2R' groups (except
hydrogen) are linked together, the entire C.sub.5R'.sub.4 group
thereby being, for example, an indenyl, tetrahydroindenyl,
fluorenyl, terahydrofluorenyl, or octahydrofluorenyl group.
[0071] Highly preferred Y groups are nitrogen or phosphorus
containing groups containing a group corresponding to the formula
--N(R'')-- or --P(R'')-- wherein R'' is C.sub.1-10 hydrocarbyl.
[0072] Most preferred complexes are amidosilane--or amidoalkanediyl
complexes.
[0073] Most preferred complexes are those wherein M is
titanium.
[0074] Specific complexes suitable for use in the preparation of
the supported catalysts of the present invention are those
disclosed in WO 95/00526 and are incorporated herein by
reference.
[0075] A particularly preferred complex for use in the preparation
of the supported catalysts of the present invention is
(t-butylamido) (tetramethyl-.eta..sup.5-cyclopentadienyl)dimethyl
silanetitanium-.eta..sup.4-1.3-pentadiene.
[0076] Suitable activators for use with the supports of the present
invention include aluminoxanes and organoboron compounds for
example boranes.
[0077] Aluminoxanes are well known as activators for metallocene
complexes. Suitable aluminoxanes, for use in the present invention,
include polymeric or oligomeric aluminoxanes in particular methyl
aluminoxane (MAO).
[0078] The aluminoxanes suitable for use in the present invention
may be commercially available materials or may be such commercially
available material that has been dried under vacuum prior to its
use for the preparation of the supported catalyst compositions.
[0079] Preferred organoboron compounds are triarylboron compounds,
in particular perfluorinated triarylboron compounds.
[0080] The most preferred organoboron compound is
tris(pentafluorophenyl) borane (FAB).
[0081] A particularly preferred activator component comprises an
organoboron compound and an organoaluminium compound.
[0082] The organoaluminium compounds are as described above. The
preferred organoaluminium compounds are triethylaluminium or
triisobutylaluminium.
[0083] Thus according to another aspect of the present invention
there is provided a supported catalyst system comprising [0084] (a)
a dehydrated support material, [0085] (b) a transition metal
compound, and [0086] (c) an activator comprising (i) an
organoaluminium compound and (ii) an organoboron compound,
characterised in that said support material has been pretreated
with at least two different organoaluminum compounds prior to
contact with either or both the transition metal compound or the
activator.
[0087] For this particular aspect of the present invention the
combination of a triarylboron compound for example
tris(pentafluorophenyl) borane and a trialkylaluminium compound for
example triethylaluminium is preferred as activator.
[0088] The ratio of boron/transition metal in this aspect of the
present invention is typically in the range 0.1 to 10 and most
preferably in the range 1 to 4.
[0089] Other compounds suitable as activators are compounds which
comprise a cation and an anion. The cation is typically a Bronsted
acid capable of donating a proton and the anion is typically a
compatible non-coordinating bulky species capable ofstabilizing the
cation.
[0090] Such activators may be represented by the formula:
(L*-H).sup.+.sub.d(A.sup.d-)
[0091] wherein
[0092] L* is a neutral Lewis base
[0093] (L*-H)+d is a Bronsted acid
[0094] A.sup.d- is a non-coordinating compatible anion having a
charge of d.sup.-, and
[0095] d is an integer from 1 to 3.
[0096] The cation of the ionic compound may be selected from the
group consisting of acidic cations, carbonium cations, silylium
cations, oxonium cations, organometallic cations and cationic
oxidizing agents.
[0097] Suitably preferred cations include trihydrocarbyl
substituted ammonium cations eg. triethylammonium,
tripropylammonium, tri(n-butyl)ammonium and similar. Also suitable
are N,N-dialkylanilinium cations such as N,N-dimethylanilinium
cations.
[0098] The preferred ionic compounds used as activators are those
wherein the cation of the ionic compound comprises a hydrocarbyl
substituted ammonium salt and the anion comprises an aryl
substituted borate.
[0099] Typical borates suitable as ionic compounds include: [0100]
triethylammonium tetraphenylborate [0101] triethylammonium
tetraphenylborate, [0102] tripropylammonium tetraphenylborate,
[0103] tri(n-butyl)ammonium tetraphenylborate, [0104]
tri(t-butyl)ammonium tetraphenylborate, [0105]
N,N-dimethylanilinium tetraphenylborate, [0106]
N,N-diethylanilinium tetraphenylborate, [0107] trimethylammonium
tetrakis(pentafluorophenyl)borate, [0108] triethylammonium
tetrakis(pentafluorophenyl)borate, [0109] tripropylammonium
tetrakis(pentafluorophenyl)borate, [0110] tri(n-butyl)ammonium
tetrakis(pentafluorophenyl)borate, [0111] N,N-dimethylanilinium
tetrakis(pentafluorophenyl)borate, [0112] N,N-diethylanilinium
tetrakis(pentafluorophenyl)borate.
[0113] The most preferred activators of this type are those wherein
the anion comprises a boron atom.
[0114] A preferred type of activator suitable for use with the
metallocene complexes of the present invention comprise ionic
compounds comprising a cation and an anion wherein the anion has at
least one substituent comprising a moiety having an active
hydrogen.
[0115] Suitable activators of this type are described in WO
98/27119 the relevant portions of which are incorporated herein by
reference.
[0116] Examples of this type of anion include: [0117]
triphenyl(hydroxyphenyl)borate [0118]
tri(p-tolyl)(hydroxyphenyl)borate [0119]
tris(pentafluorophenyl)(hydroxyphenyl)borate [0120]
tris(pentafluorophenyl)(4-hydroxyphenyl)borate
[0121] Examples of suitable cations for this type of activator
include triethylammonium, triisopropylammonium,
diethylmethylammonium, dibutylethylammonium and similar.
[0122] Particularly suitable are those cations having longer alkyl
chains such as dihexyldecylmethylaammonium,
dioctadecylmethylammonium, ditetradecylmethylammonium,
bis(hydrogentated tallow alkyl)methylammonium and similar.
[0123] Particular preferred activators of this type are
alkylammonium tris(pentafluorophenyl) 4-(hydroxyphenyl)borates. A
particularly preferred activator is bis(hydrogenated tallow
alkyl)methyl ammonium tris(pentafluorophenyl) (4
hydroxyphenyl)borate.
[0124] With respect to this type of activator, a preferred compound
is the reaction product of an alkylammonium
tris(pentaflurophenyl)-4-(hydroxyphenyl)borate and an
organometallic compound, for example triethylaluminium.
[0125] The supported catalyst systems of the present invention are
most suitable for operation in processes which typically employ
supported polymerisation catalysts.
[0126] The supported catalysts of the present invention may be
suitable for the polymerisation of olefin monomers selected from
(a) ethylene, (b) propylene (c) mixtures of ethylene and propylene
and (d) mixtures of (a), (b) or (c) with one or more other
alpha-olefins.
[0127] Thus according to another aspect of the present invention
there is provided a process for the polymerisation of olefin
monomers selected from (a) ethylene, (b) propylene (c) mixtures of
ethylene and propylene and (d) mixtures of (a), (b) or (c) with one
or more other alpha-olefins, said process performed in the presence
of a supported catalyst system as hereinbefore described.
[0128] The supported catalyst systems of the present invention are
however most suitable for use in slurry or gas phase processes.
[0129] A slurry process typically uses an inert hydrocarbon diluent
and temperatures from about 0.degree. C. up to a temperature just
below the temperature at which the resulting polymer becomes
substantially soluble in the inert polymerisation medium. Suitable
diluents include toluene or alkanes such as hexane, propane or
isobutane. Preferred temperatures are from about 30.degree. C. up
to about 200.degree. C. but preferably from about 60.degree. C. to
100.degree. C. Loop reactors are widely used in slurry
polymerisation processes.
[0130] Gas phase processes for the polymerisation of olefins,
especially for the homopolymerisation and the copolymerisation of
ethylene and .alpha.-olefins for example 1-butene, 1-hexene,
4-methyl-1-pentene are well known in the art.
[0131] Typical operating conditions for the gas phase are from
20.degree. C. to 100.degree. C. and most preferably from 40.degree.
C. to 85.degree. C. with pressures from subatmospheric to 100
bar.
[0132] Particularly preferred gas phase processes are those
operating in a fliidised bed. Examples of such processes are
described in EP 89691 and EP 699213 the latter being a particularly
preferred process for use with the supported catalysts of the
present invention.
[0133] Particularly preferred polymerisation processes are those
comprising the polymerisation of ethylene or the copolymerisation
of ethylene and .alpha.-olefins having from 3 to 10 carbon
atoms.
[0134] Thus according to another aspect of the present invention
there is provided a process for the polymerisation of ethylene or
the copolymerisation of ethylene and .alpha.-olefins having from 3
to 10 carbon atoms, said process performed under polymerisation
conditions in the present of a supported catalyst system as
hereinbefore described.
[0135] The preferred .alpha.-olefins are 1-butene, 1-hexene,
4-methyl-1-pentene and 1-octene.
[0136] The supported catalysts prepared according to the present
invention may also be suitable for the preparation of other
polymers for example polypropylene, polystyrene, etc.
[0137] It has been surprisingly found that the supported catalyst
systems described herein may be used to prepare copolymers having a
broad molecular weight distribution as well as improved melt
strengths.
[0138] Copolymers may be prepared which exhibit a molecular weight
distribution (Mw/Mn) of >2 and preferably >3.
[0139] The copolymers also exhibit melt strength values (16 Mpa) in
the range 3-12 cN and preferably in the range 3-9 cN.
[0140] The copolymers are preferably prepared by use of a supported
metallocene catalyst system as hereinbefore described.
[0141] Thus according to another aspect of the present invention
there is provided a process for the preparation of copolymers of
ethylene and alpha-olefins having
[0142] (a) melt strength in the range 3-12 cN, and
[0143] (b) a Mw/Mn of >2.
said process comprising contacting ethylene and one or more
alpha-olefins in the presence of a supported metallocene catalyst
system as hereinbefore described.
[0144] The preferred supported catalyst system for this aspect of
the present invention is that wherein the transition metal compound
is a monocyclopentadienyl metallocene complex as hereinbefore
described.
[0145] The preferred process for the preparation of such copolymers
is a gas phase process.
[0146] The present invention also encompasses a dehydrated catalyst
support material characterised in that the support-material has
been treated with at least two different organoaluminium compounds
prior to the addition of further catalytic components.
[0147] The process of the present invention will now be illustrated
by reference to the following examples.
EXAMPLES
Abbreviations Used
[0148] FAB trispentafluorophenylboranie [0149] TEA
triethylaluminium [0150] TiBA trisobutylaluminum [0151] Ionic
Activator A
[N(H)Me(C.sub.18H.sub.37).sub.2][B(C.sub.6F.sub.5).sub.3(p-OHC.sub.6H.sub-
.4)] [0152] Complex A (t-butylamido)
(tetaamethyl-.fwdarw..sup.5_cyclopentadienyl)dimethyl
silanetitanium-.fwdarw..sup.4-1,3-pentadiene
[0153] All catalyst preparation steps were performed in a inert
atmosphere filled glove-box using standard Schlenk and cannulae
techniques.
Example 1
[0154] To 5 g of Ineos ES70 silica (previously calcined at
500.degree. C. for 5 hours under nitrogen, pore volume 1.55 ml/g)
was added 2.04 ml of an hexane solution of triethylaluminium (TEA),
0.98 mol/l, (0.4 mmol Al/g silica) followed by the addition of 1.58
ml of an hexane solution of TiBA, 0.95 mol/l (0.3 mmol Al/g
silica). The mixture was allowed to react for 2 hours then dried
under vacuum.
[0155] To 0.77 g of trispentafluorophenylborane (1.5 mmol) was
added 5 ml of toluene. 1.53 ml of a solution of triethylaluminum in
hexane, 1 mol/l, were then added and the solution was stirred for
30 minutes.
[0156] The trispentafluorophenylalane above was added to the
TEA-TiBA treated silica (at pore volume) and then heated at
85.degree. C. for 2 hours, followed by drying at the same
temperature
[0157] 1.4 ml of Complex A solution in heptane (9.17% wt) was then
slowly added (15 min) and manually agitated until no lumps were
visible. After one hour holding the catalyst was then dried under
vacuum.
[Ti]=66 .mu.mol/g final catalyst; [Al]=0.908 mmol/g final
catalyst
Polymerisation Data
[0158] A 2.5 l double jacketed thermostatic stainless steel
autoclave was purged with nitrogen at 70.degree. C. for at least
one hour. PE pellets previously dried under vacuum at 80.degree. C.
for 12 hours were introduced and the reactor was then purged three
times with nitrogen (7 bar to atmospheric pressure). .about.0.13 g
of TEA treated silica (1.5 mmol TEA/g) was added under pressure and
allowed to scavenge impurities for at least 15 minutes under
agitation. The gas phase was then composed (addition of ethylene,
1-hexene and hydrogen) and a mixture of supported catalyst
(.about.0.1 g) and silica/TEA (.about.0.1 g) was injected. A
constant pressure of ethylene and a constant pressure ratio of
ethylene/co-monomer were maintained during the run. The run was
terminated by venting the reactor and then purging the reactor 3
times with nitrogen. The PE powder produced during the run was then
separated from the PE seed bed by simple sieving.
Typical conditions are as follows:
200 g of PE pellets as bed
T=70.degree. C.
PC2=6.5 Bar.
PC6/PC2=0.0048
SiO2/TEA impregnated used as scavenger.
H2 added during the gas phase composition: 150 ml
Catalyst quantity: 200 mg
Polymerisation time=60 min
[0159] At the end of the polymerisation reaction, polymer produced
separated from polymer bed by simple sieving was obtained having
the following properties: TABLE-US-00001 Activity: 24 g/ghb MI
(2.16 kg) 0.81 g/10 min Density 0.926 g/ml Mn 19300 g/mol Mw 114125
g/mol Mw/Mn 5.9 Melt strength(16 Mpa) 7.6 (cN)
Example 2
[0160] To 10 g of Grace 948 silica (previously calcined at
250.degree. C. for 5 hours under nitrogen) was added 7.8 ml of an
hexane solution of triethylaluminium (TEA), 1.027 mol/l, (0.8 mmol
Al/g silica) followed by the addition of 8.4 ml of an hexane
solution of triisobutylaluminium (TiBA), 0.952 mol/l (0.8 mmol Al/g
silica). The mixture was allowed to react for 2 hours then the
silica was decanted, washed three times and dried under vacuum.
[Al]=1.35 mmol/g (ICP measurment)
[0161] 1.48 mls of a solution of ionic activator A (11.1 wt % in
toluene) was reacted with 0.25 ml TEA in toluene (0.25 mol/l)
(molar ratio Al/B=0.5). 4 g of the above passivated silica was
slowly impregnated (15 min) with the ionic actiator solution and
manually agitated until no lumps were visible followed by 30 min
holding.
[0162] 70 ml of Complex A solution in heptane (9.17% wt) was then
slowly added (15 min) and manually agitated until no lumps were
visible followed by 30 min holding. 10 ml of hexane was the added
and the suspension was stirred for 15 minutes. The catalyst was
washed 3 times with 20 ml of essence and then dried under
vacuum.
[Ti]=31 .mu.mol/g; [AI]=1.28 mmolg
Polymerisation Data
The same procedure as described above for Example 1 was used.
Run Conditions
116 g of PE pellets as bed
T=70.degree. C.
PC2=6.5 Bar.
% vol C6/PC2=0.74
SiO2/TEA impregnated used as scavenger.
H2 added during the gas phase composition: 50 ml
catalyst quantity: 103 mg
Polymerisation time=90 min
[0163] At the end of the polymerisation reaction, polymer produced
(77 g) separated from polymer bed by simple sieving TABLE-US-00002
Activity: 88 g/ghb MI (2.16 kg) 1.02 g/10 min MI (21.6 kg) 25.02
MFR 25 Density 0.917 g/ml Mn 37000 g/mol Mw 114000 g/mol Mw/Mn 3.1
Melt strength (16 Mpa) 3.6 (cN)
[0164] Product characteristics were determined using the following
analytical procedures:
Melt Flow Rate (2.16 kg)
[0165] The melt flow rate (OR) of the polymers was measured under
conditions which conform to ISO 1133 (1991) and BS 2782:PART
720A:1979 procedures. The weight of polymer extruded through a die
of 2.095 mm diameter, at a temperature of 190.degree. C., during a
600 second time period and under a standard load of 2.16 kg is
recorded.
Molecular Structure Characterisation
[0166] Various techniques (eg .sup.13C NMR, GPC/LALLS,
GPC/intrinsic viscosity, GPC/on-line viscometry and rheological
flow activation energy, etc) have been developed to indicate the
presence of long chain branching in polymers.
Molecular Weight Distribution (M.sub.w/M.sub.n)
[0167] Molecular weight distribution and associated averages, were
determined by Gel Permeation Chromatography using a Waters GPCV
2000. The Millennium version 3.05.01 software supplied by Waters
was used for data treatment. The solvent used was 1,2,4
Trichlorobenzene at 150.degree. C., stabilised with 0.05% BHT. The
nominal flow rate was 1 ml/min. Solutions of concentration around
0.1% w/w were prepared at 150.degree. C. for 2 hours on a hot
plate, and the nominal injection volume was set at 217.5 ml. 2
Shodex AT806M/S and 1 Waters HT2 columns were used with a plate
count (at half height) of typically 28,000. The system was
calibrated using 12 polystyrene standards supplied by Polymer
Laboratories.
[0168] Apparent molecular weight distribution and associated
averages, uncorrected for long chain branching, were determined
using the differential refractometer detector alone. Molecular
weight of Ps standards were converted to polyethylene molecular
weights using the Mark Houwink parameters
K.sub.ps=1.75.times.10.sup.-4 dl/g, .quadrature..sub.ps=0.67,
[0169] K.sub.pe=4.1.times.10.sup.-4 dl/g, .quadrature..sub.pe=0.706
[Polymer Handbook, J. Bandrup and E. H. Immergut, 3.sup.rd
Edition].
[0170] This calibration has been checked against the NIST certified
polyethylene SRM1475, the values obtained being 54,100 g/mol for
M.sub.w and 17,300 g/mol for M.sub.n.
Melt Strength
[0171] The melt strength of the polymer is measured at 190.degree.
C., using a Gottfert Rheotens extensional rheometer in conjunction
with a Rosand RH 7 Capillary Rheometer. This is achieved by
extruding the polymer at a constant pressure (P) through a die of
1.5 mm diameter and 30 mm in length, with a 90.degree. entry angle.
Once a given extrusion pressure is selected, the piston of the
capillary rheometer will travel through its 15 mm diameter barrel
at a speed that is sufficient to maintain that pressure constant.
The nominal wall shear rate ({dot over (.gamma.)}) for a given
extrusion pressure can then be computed for the polymer at the
selected pressure using the constant pressure ratio system of the
rheometer.
[0172] The extrudate is drawn with a pair of gear wheels at an
accelerating speed (V). The acceleration ranges from 0.12 to 1.2
cm/s.sup.2 depending on the flow properties of the polymer under
test. The drawing force (F) experienced by the extrudate is
measured with a transducer and recorded on a chart recorder
together with the drawing speed. The maximum force at break is
defined as melt strength (MS) at aconstant extrusion pressure (P)
or at its corresponding extrusion rate ({dot over (.gamma.)}).
Three or four extrusion pressures (6, 8, 12, 16 MPa) are typically
selected for each polymer depending on its flow properties. For
each extrusion pressure, a minimum of 3 MS measurements is
performed and an average MS value is then obtained.
[0173] The derivative function of the extrusion pressure dependent
melt strength, .delta.(MS)/.delta.(P) for each polymer is computed
from the slope (by a least square line fitting) of the plot of the
average MS against pressure. The mean melt strength at an extrusion
pressure of 16 MPa, MS (16 MPa), can be computed from the plot.
* * * * *