Note: Descriptions are shown in the official language in which they were submitted.
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POLYMERIZATION CATALYST SYSTE1VIS. THEIR
PRODUCTION AND USE
FIELD OF THE IN'~ENTION
This invention relates to catalysis, catalyst systems and eo methods for their
production and use in olefin polymerization. The invention particularly
relates to a
process for preparing a bulky ligand transition metal catalyst system for use
in the
gas phase, slurry phase or liquid/solution phase.
l0
BACKGROUND OF THE INVENTION
A new catalyst technology has developed which provides for the
modification and/or control over the properties and characteristics of a
polymer.
These new catalysts are referred to as bulky ligand transition metal
catalysts which are formed from a bulky ligand transition metal compound and
an
activator. The bulky Ggand of the transition metal compound may contain a
multiplicity of bonded atoms, preferably carbon atoms and typically contain a
cyclic structure such as, for example, a cyclopentadienyl ligand or a
substituted
cyclopentadienyl ligand, or any other ligand capable of tl-5 bonding to the
transition metal. The iransition metal is typically a Group 4, 5 or 6
transition metal
or may be a metal from the lanthanide and actinide series. Other ligands may
be
bonded to the transition metal, such as but not limited to hydrocarbyl,
halogen or
any other anionic ligand. Generally, in the art, these bulky ligand catalysts
are
referred to as metallocene catalysts.
U.S. Patent No. 5,308,817, discusses that storage of a metallocene/
methylalumoxane solution at room temperature under nitrogen for several days
resulted in gradual increases in polymer yields with specific syndiospecific
metallocenes.
It would be highly desirable to have a process for producing higher activity
polymerization catalyst systems that are independent of the bulky Iigand
transition
metal catalyst component or metallocene.
SUMMARY OF THE INVENTION
This invention is generally directed towards a new polymerization catalyst
3 5 system, to methods for its manufacture and to its use in a polymerization
process.
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In one embodiment an improved method is provided to produce a bulky
ligand transition metal catalyst system by contacting a metallocene catalyst
component with an activator that has been aged.
In another embodiment the bulky ligand transition metal catalyst system
described above is supported on a carrier.
In yet another embodiment of the invention, there is provided a process for
producing polyolefins by contacting olefin monomer, optionally with comonomer
in the presence of the catalyst systems described above.
In yet another embodiment there is provided a catalyst system produced by
the improved method.
DETAILED DESCRIPTION OF THE INVENTION
Introduction
This invention is generally directed toward a catalyst system, preferably a
supported catalyst system, useful for polymerizing olefins. The method for
forming the catalyst system of the invention involves contacting a metallocene
catalyst component or compound with an activator or a cocatalyst that has been
aged.
It has been discovered that in forming the catalyst system of the invention,
where the activator has been stored for a period of time or aged the activity
of the
resulting catalyst system produced with the aged activator increases. In
addition to
the increase in polymer yields, the process of the invention permits the
reduced
loading of the catalyst and activator components. This reduction in loading
results
in a more cost effective catalyst system. Also, it has been discovered that
high
loadings can result in an increase of a catalyst systems' tendency to sheet or
foul
during polymerization. Reducing the loading typically reduces catalyst
activity and
sheeting and fouling tendencies, however, using the process of this invention
catalyst activity can be maintained or even increased.
Catatvst Components of the Invention
Metallocene catalysts, for example, are typically those bulky ligand
transition metal compounds derivable from the formula:
~~mM~AJn
where L is a bulky ligand; A is leaving group, M is a transition metal and m
and n
3 S are such that the total ligand valency corresponds to the transition metal
valency.
AMENDED SHEE3
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Preferably the catalyst is four co-ordinate such that the compound is
ionizable to a
1+ valence state,
The Ggands L and A may be bridged to each other, and if two Ggands L
and/or A are present, they may be bridged. The metallocene compound may be
full-sandwich compounds having two or more ligands L which may be
cyclopentadienyl ligands or cyclopentadiene derived ligands or half sandwich
compounds having one Ggand L, which is a cyclopentadienyl ligand or derived
ligand.
The metallocene compounds contain a multiplicity of bonded atoms,
i0 preferably carbon atoms, and rypicalty contain a cyclic structure such as,
for
example, a substituted or unsubstituted cycloperitadienyl ligand, or
cyclopentadienyl derived ligand or any other Iigand capable of rl-5 bonding to
the
transition metal atom. One or more bulky ligands may be n-bonded to the
transition metal atom. The transition metal atom may be a Group 4, 5 or 6
transition metal and/or a metal from the lanthanide and actinide series, Other
ligands may be bonded to the trarrsieion metal, such as a leaving group, such
as but
not limited to hydrocarbyl, halogen or any other univalent anionic ligand. Non-
limiting examples of metallocene catalysts and catalyst systems are discussed
in for
example, U.S. Patent Nos. 4,530,914, 4,952,716, 5,124,418, 4,808,561,
4,897,455, 5,278,119, 5,304,614, EP-A-0129,368, EP-A-0520732, EP-A
0420436, WO 91/04257, WO 92/00333, WP 93/08221, and WO 93/08199.
Various forms of the catalyst system of the metallocene type may be used
ZS in the polymerization process of this invention. Exemplary of the
development of
metallocene catalysts in the art for the polymerization of ethylene is the
disclosure
of U.S. Patent No. 4,871,705 to T3oel, U.S. Patent No. 4,937,299 to Ewen, et
al.,
5,324,800 and EP-A-0 129 368, and U.S. Patent Nos. 5,017,714 and 5,120,867.
These publications teach the structure of the metallocene catalysts and
include
3 0 alumoxane as the catalyst. There are a variety of methods for preparing
alumoxane, non-limiting examples of which are described in U.S. Patent No.
4,665,208, 4,952,540, 5,091,352, 5,206,199, 5,204,419, 4,874,734, 4,924,018,
4,908,463, 4,968,827, 5,308,815, 5,248,801, 5,235,081, 5,157,137, 5,103,031
and
EP-A-0 561 476, EP-Bl-0 279
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586, EP-A-0 594-218 and WO 94/10180.
Further, the metallocene catalyst component of the invention can be a
monocyclopentadienyl heteroatom containing compound. This heteroatom is
activated by either an alumoxane, an ionizing activator, a Lewis acid or a
combination thereof to form an active polymerization catalyst system. These
types
of catalyst systems are described in, for example, PCT International
Publication
WO 92/00333, WO 94/07928, and WO 91/ 04257, WO 94!03506, U.S. Patent
Nos. 5,057,475, 5,096,867, 5,055,438, 5,I98,40I, 5,227,440 and 5,264,405 and
EP-A-0 420 436. In addition, the metallocene catalysts useful in this
invention
can include non-cyclopentadienyl catalyst components, or ancillary ligands
such
as boroles or carbollides in combination with a transition metal. Additionally
it is
not beyond the scope of this invention that the catalysts and catalyst systems
may
be those described in U.S. Patent Nos. 5,064,802, 5,149,819, 5,243,001,
5,239,022, 5,276,208, 5,296,434, 5,321,106 and 5,304,614, PCT publications
WO 93/08221 and WO 93/08199 and EP-A- 0 578 838.
The preferred transition metal component of the catalyst of the invention
are those of Group 4, particularly, zirconium, titanium and hafnium. The
transition
metal may be in any oxidation state, preferably +3 or +4 or a mixture thereof.
All
the catalyst systems of the invention may be, optionally, prepolymerized or
used in
conjunction with an additive or scavenging component to enhance catalytic
productivity, see for example PCT publication WO 94/07927.
For the purposes of this patent specification the term "metallocene" is
defined to contain one or more unsubstituted or substituted cyclopentadienyl
or
cyclopentadienyl moiety in combination with a transition metal. In one
embodiment the metallocene catalyst component is represented by the general
formula (Cp)mMRnR'p wherein at least one Cp is an unsubstituted or,
preferably, a
substituted cycIopentadienyl ring symmetrically or unsymetrically substituted;
M is
a Group 4, 5 or 6 transition metal; R and R' are independently selected
halogen,
hydrocarbyl group, or hydrocarboxyl groups having 1-20 carbon atoms or
combinations thereof; m=1-3, n=0-3, p~-3, and the sum of m+n+p equals the
oxidation state of M.
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In another embodiment the metallocene catalyst component is represented
by the formulas:
(CSR~rr~pRns(CSR~m)MQ3-p-x ~d
S
R"s(CSR,m)2MQ,
wherein M is a Group 4, 5, 6 transition metal, at least one CSR'm is a
substituted
cyclopentadienyl, each R', which can be the same or different is hydrogen,
alkyl,
alkenyl, aryl, alkylaryl or arylalkyl radical having from 1 to 20 carbon atoms
or two
carbon atoms joined together to form a part of a substituted or unsubstituted
ring
or rings having 4 to 20 carbon atoms, R" is one or more of or a combination of
a
carbon, a germanium, a silicon, a phosphorous or a nitrogen atom containing
radical bridging two (C5R'~ rings, or bridging one (C5R'm) ring back to M,
when
p = 0 and x = 1 otherwise "x" is always equal to 0, each Q which can be the
same
or different is an aryl, alkyl, aikenyl, alkylaryl, or arylalky! radical
having from 1 to
carbon atoms, halogen, or alkoxides, Q' is an alkylidene radical having from 1-
20 carbon atoms, s is 0 or 1 and when s is 0, m is 5 and p is 0, 1 or 2 and
when s is
l,mis4andpisl.
20 For the purposes of this patent specification, the terms "cocatalysts" and
"activators" are used interchangeably and are defined to be any compound or
component which can activate a bulky ligand transition metal compound or a
metallocene, as defined above. It is within the scope of this invention to use
alumoxane as an activator, and to also use ionizing activators, neutral or
ionic, or
compounds such as tri (n-butyl) ammonium tetra bis(pentaflurophenyl) boron,
which ionize the neutral metallocene compound. Such ionizing compounds may
contain an active proton, or some other ration associated with but not
coordinated
or only loosely coordinated to the remaining ion of the ionizing compound.
Such
compounds and the Like are described in EP-A-0520 732, BP-A-500 944, EP-A-0
277 003 and EP-A-0 277 004, and U.S. Patent Nos. 5,153,157, 5,198,401, and
5,241,025. Combinations of activators are also contemplated by the invention,
for
example, alumoxane and ionizing activators in combinations, see for example
WO 94/07928.
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'The preferred activator is alumoxane and even more preferred is alumoxane
produced in situ as described in various U.S. Patent Nos. 5,008,228, 5,086,025
and 5,147,949.
For purposes of this patent specification the terms "carrier" or "support"
are interchangeable and can be any support material, preferably a porous
support
material, such as for example, talc, inorganic oxides, inorganic chlorides,
for
example magnesium chlaride and resinous support materials such as polystyrene
polyolefin ar polymeric compounds or any other organic support material and
the
like.
The preferred support materials are inorganic oxide materials, which
include those from the Periodic Table of Elements of Groups 2, 3, 4, 5, 13 or
14
metal oxides. In a preferred embodiment, the catalyst support materials
include
silica, alumina, silica-alumina, and mixtures thereof. Other inorganic oxides
that
may be employed either atone or in combination with the silica, alumina or
silica-
alumina are magnesia, titania, zirconia, and the like.
It is preferred that the carrier of the catalyst of this invention has a
surface
area in the range of from about 10 to about 700 m2/g, pare volume in the range
of
from about 0.1 to about 4.0 ccJg and average particle size in the range of
from
about 10 to about 500 pm. More preferably, the surface area is in the range of
from about SO to about 500 m2/g, pore volume of from about 0.5 to about 3.5
cc/g
and average particle size of from about 20 to about 200 ~tm. Most preferably
the
surface area range is from about 100 to about 400 m2lg, pore volume from about
0.8 to about 3.0 ccJg and average particle size is from about 30 to about 100
um.
The pore size of the carrier of the invention typically.is in the range of
from I O to
1000°A, preferably 50 to about 500°A, and most preferably 75 to
about 350°A.
Method of Producing the Catalyst System of the Invention
The catalyst system of the invention can be made in a variety of different
ways.
The activator of the invention can be stored by any reasonable method
under any reasonable conditions as is well known in the art. The activator of
the
invention can be stored at various temperatures, pressures, in various liquids
under
a variety of inert gases, etc.
The longer the length of time the activator is stored the more active the
catalyst system ofthe invention becomes. It is within the scope of this
invention to
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reduce the storage time of the activator by modifying the storage conditions
in and
under which the activator is kept. Non-limiting examples of storage conditions
are temperature, pressure, type of gas, or solvent etc, in and under which the
activator is subjected a Other storage conditions that can be altered include
the
container in which the activator is kept or whether the activator is kept
undisturbed
or continuously or semi-continuously agitated.
For the purposes of this patent specification and appended claims the term
an "aged activator" is an activator that has been stored for a period of time
from
the time of its initial manufacture until its use in the methods of the
invention or
IO has been subjected to conditions that accelerate the aging process and
thereby
reducing storage time from the time the activator is prepared.
In one embodiment the aged activator of the invention is stored under
ambient conditions from the time of its manufacture for a period of time
greater
than about 24 hours, preferably greater than about 168 hours, more preferably
greater than about 336 hours, even more preferably greater than about 672
hours
and still even more preferably greater than about 840 hours and most
preferably
greater than about 1000 hours.
In another embodiment the aged activator is stored with, on or in the
support material for a period of time as above.
In the preferred embodiment the activator is alumoxane that is prepared by
contacting a water containing support with an organo metallic compound,
preferably trimethyIaluminum, in a solvent. The resulting slurry is then
stored at
room temperature under nitrogen for several days, weeks, months or even years
or
stored under storage conditions previously discussed that would accelerate the
aging process and reduce storage time.
Preferably the mole ratio of the metal of the organometallic compound to
water present in the support is in the range of from 0.7 to 10, preferably 0.8
to 6,
even more preferably 0.9 to 4, still even more preferably 0.9 to 3 and most
preferably 0.9 to 1.3. The mole ratio and length of aging time of the
activator can
be adjusted to achieve a desired end result, for example, a particular
activity or
product capability.
In one embodiment the "aged activator" is a translucent solution that is
hazy and/or contains gels even after shaking or stirring the solution
vigorously
after a period of aging.
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The catalyst system of the invention can be formed by any method well
known in the art, some of which have been described in the various references
cited in this patent specification.
The metallocene component, the aged activator and optionally the support
S can be combined in a variety of ways. hton-linuting embodiments of the
invention
are as follows. ( I ) The metallocene can be added to the aged activator or
vice
versa. (2) The combination of the metallocene and aged activator of the
invention
can be contacted with a support material or vice-versa. The activator of the
invention can be contacted with a support material first followed by the
addition of
the metallocene. (3) A metallocene catalyst component of the invention can be
contacted with a support maternal first, followed by the addition of the aged
activator of the invention. (4) The aged activator of the invention can be
formed in
situ on or in a support material, followed by the addition of the metallocene
catalyst component. (5) The aged activator of the invention can be separately
supported from the metallocene catalyst component with or without an aged
activator or any other activator or combination. (b) The aged activator of the
invention can be added directly into the polymerization reactor in a
supported,
liquid, dry or slurry form in combination with or without a metallocene
catalyst
component. (7) The aged activator of the invention can be combined with any
other activator in any of the previous non-limiting embodiments.
In another embodiment of the invention, the mole ratio of the metal of the
aged activator component to the transition metal of the metalIocene component
is
in the range of ratios between 0.3:1 to 1000: l, preferably 20:1 to 800:1, and
most
preferably 50:1 to 500:1. In another embodiment where the aged activator is an
ionizutg activator as previously described the mole ratio of the metal of the
activator component to the transition metal component is in the range of
ratios
between 0.3:1 to 3:1.
It is within the scope of this invention to wash the catalyst system of the
invention in a liquid, such as hexane, after its partial or complete formation
and
then dry the catalyst system or portion of the catalyst system to remove
excess
liquid.
In another embodiment of the invention, the supported catalyst system of
the invention includes a modifying agent, for example, those described in U.S.
Patent No. 5,283,278. Non-limiting examples of modifying agents include,
alcohol, thiol, silanol, diol, ester, ketone,
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aldehyde, acid, amine, and ether compounds. Tertiary amine compounds are
preferred. The modifying agent can be added at any stage in the formation of
the
supported catalyst system of the invention, however, it is preferred that it
is added
after the supported catalyst system of the invention is formed, in either a
slurry or
dried state.
In another embodiment of the invention, the supported catalyst system of
the invention includes a polyolefin wax or tackifier or the like.
Polymerization Process of the Invention
The catalyst system of this invention is suited for the polymerization of
monomers and optionally comonomers in any polymerization or prepolymerization
process, gas, slurry or solution phase; even a high pressure autoclave process
can
be utilized. In the preferred embodiment a gas phase or slurry phase process
is
utilized, most preferably a gas phase process is used.
In the preferred embodiment, this invention is directed toward the slurry or
gas phase polymerization or copolymerization reactions involving the
polymerization or optionally prepolymerization of one or more of the alpha-
olefin
monomers having from 2 to 20 carbon atoms, preferably 2-12 carbon atoms. The
invention is particularly well suited to the copolymerization reactions
involving the
polymerization of one or mare of the monomers, for example alpha-olefin
monomers of ethylene, propylene, butene-1, pentene-1, 4-methylpentene-1,
hexene-1, octene-1, decene-l, and cyclic olefins and styrene. Other monomers
can
include polar vinyl, diolefins such as dienes, norbornene, norboradiene,
acetylene
and aldehyde monomers. Preferably a copolymer of ethylene or propylene is
'?5 produced. Preferably the comonomer is an alpha-olefin having from 3 to 15
carbon atoms, preferably 4 to 12 carbon atoms and most preferably 4 to 10
carbon
atoms. In another embodiment ethylene or propylene is polymerized with at
least
two comonomers to form a terpolymer and the like.
In one embodiment of the process of the invention, the olefins) are
prepolymerized in the presence of the catalyst system of the invention prior
to the
main polymerization. The prepolymerization can be carried out batchwise or
continuously in gas, solution or slurry phase including at elevated pressures.
The
prepolymerization can take place with any alpha-olefin monomer or combination
andlor in the presence of any molecular weight controlling agent such as
hydrogen.
For details on prepolymerization see U.S. Patent No. 4,923,833 and 4,921,825
and
AMENDED SHEET
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EP-B-0279 863, published October 14, 1992. All the catalyst systems of the
invention may be optionally prepolymerized or used in conjunction with an
additive or scavenging component to enhance catalytic productivity.
Typically in a gas phase polymerization process a continuous cycle is
employed where in one part of the cycle of a reactor, a cycling gas stream,
otherwise known as a recycle stream or fluidizing medium, is heated in the
reactor
by the heat of polymerization. This heat is removed in another part of the
cycle by
a cooling system external to the reactor. (See far example ~J.S. Patent Nos.
4,543,399, 4,588,790, 5,028,6?0 and 5,352,749.)
Generally in a gas fluidized bed process for producing polymer from
monomers a gaseous stream containing one or more monomers is continuously
cycled through a fluidized bed in the presence of a catalyst under reactive
conditions. The gaseous stream is withdrawn from the fluidized bed and
recycled
back into the reactor. Simultaneously, polymer product is withdrawn from the
reactor and new or fresh monomer is added to replace the polymerized monomer.
A slurry polymerization process generally uses pressures in the range of
about 1 to about 500 atmospheres and even greater and temperatures in the
range
of -60°C to about 280°C. In a slurry polymerization, a
suspension of solid,
particulate polymer is formed in a liquid polymerization medium to which
ethylene
and comanomers and often hydrogen along with catalyst are added. The liquid
employed in the polymerization medium can be alkane or cycloalkane, or an
aromatic hydrocarbon such as toluene, isobutylene, ethylbenzene or xylene. The
medium employed should be liquid under the conditions of polymerization and
relatively inert. Preferably, hexane or isobutane is employed.
In some instances where it is necessary to improve processability and
manipulate final end product characteristics the polymers produced by this
present
invention can be blended or coextruded into single or multilayer films or the
like
with various other polymers and compounds well known in the art, for instance,
LLDPE, LDPE, high and low high density polyethylene, polypropylene, PB, EMA,
EVA, copolymers of acrylic acid, palymethylacrylate ar any other polymers such
as polyvinylchloride, polybutene-I, isatactic polybutene, ABS resins, ethylene-
propyiene rubber, vulcanized ethylene-propylene rubber, EPDM black copolymer
elastomers, copolymers of ethylene and vinyl alcohol, polystyrene, nylons, PET
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resins, crosslinked polyethylenes, poly-1-esters, graft copolymers,
polyacrylonitrile
homopolymers or copolymers, thermoplastic polyamides, polyacetal,
polyvinylidine
fluoride and other fluorinated elastomers, polyethylene glycols,
polyisobutyiene,
terpene resins and other tackifying polymers and the like and combinations
thereof.
In many applications it will desirable to combine the polymer of the
invention with anti-oxidants, slip, anti-block, processing aids, pigments,
ultra-violet
inhibitors, antistatic agents, or other additives. The polymers produced by
the
process of the invention are useful in such forming operations as film, sheet,
and
fiber extrusion and co-extrusion as well as blow molding, injection molding
and
rotary molding. Films include blown or cast films in mono-layer or multilayer
constructions formed by coextrusion or by lamination. Such films are usefi.tl
as
shrink film, cling film, stretch film, sealing films, oriented films, snack
packaging,
heavy duty bags, grocery sacks, baked and frozen food packaging, medical
packaging, industrial liners, membranes, etc. in food-contact and non-food
contact
applications. Fiber forming operations include melt spinning, solution
spinning and
melt blown fiber operations. Such fibers may be used in woven or non-woven
form
to make filters, diaper fabrics, medical garments, geotextiles, etc. General
extruded
articles include medical tubing, wire and cable coatings, geomembranes, and
pond
liners. Molded articles include single and mufti-layered constructions in the
form of
bottles, tanks, large hollow articles, rigid food containers and toys, etc.
EXAMPLES
In order to provide a better understanding of the present invention
including representative advantages and limitations thereof, the following
examples
are offered.
Density is measured in accordance with ASTM~D-1238. The ratio of
Mw/Mn can be measured directly by gel permeation chromatography techniques.
For the purposes of this patent specification the Mw/Mn of a polymer is
determined with a WatersTT'' Gel Permeation Chromatograph equipped with
Ultrastyrogel~ columns and a refractive index detector. In this development,
the
operating temperature of the instrument was set at 145°C, the eluting
solvent was
trichlorobenzene, and the calibration standards included sixteen polystyrenes
of
precisely known molecular weight, ranging from a molecular weight of 500 to a
molecular weight of 5.2 million, and a polyethylene standard, NBS 1475.
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Comparative Exam~fe 1
wt% Trimethyl aluminum (TMA) in isopentane (3380 cm3) was
measured into a 5-liter flask at OoC. 400 g of Davison 948 silica having Loss-
On-
Ignition (LOI) of 11.14% was added slowly to the TMA solution. (The weight
5 percent water is measured by determining the weight loss of the support
material
which has been heated and held at a temperature of about 1000°C for
about 16
hours. This is known as the LOI procedure.) A.Rer all the silica had been
added,
the temperature was raised to 35oC and the isopentane solvent was removed
under
vacuum to give a free-flowing powder. A sample of the powder (10 g) was
10 suspended it 60 cm3 heptane at 60oC. To this slurry was added a solution of
0.2925 g (nPentCp)2ZrC12 in toluene (40 cm3). Stirring v~ias continued for 1.5
h
and then the solvent was removed under vacuum to give a free-flowing catalyst.
The supported catalyst described above was used in polymerizing ethylene
in a semi-batch gas-phase reactor utilizing NaCI as seed bed and at 85oC. The
pressure in the reactor was held constant by continuously feeding ethylene to
make
up for consumption due to polymerization. After 30 minutes, the polymer
produced (61 g) was separated from the seed bed and the e~ciency of the
catalyst
was calculated and normalized to 1 h and 150 psi (1034 kPa) monomer
concentration as shown in Table 1.
Comparative Example 2
10 wt-% Trimethyl aluminum in isopentane (284 cm3) was measured into a
500-cc flask at OoC. 20 g of Davison 948 silica having Loss-On-Ignition of
11.14% was added slowly to the TMA solution. After all the silica had been
added, the temperature was raised to 35oC and the isopentane solvent was
removed under vacuum to give a free-flowing powder. A sample of the powder
( 10 g) was suspended in 60 cm3 heptane at 60oC. To this slurry was added a
solution of 0.2925 g (nPentCp)2ZrC12 in toluene (35 cm3). Stirring was
continued
for 1.5 h and then the solvent was removed under vacuum to give a free-flowing
catalyst. This catalyst was then used to polymerize ethylene as described in
Example 1. The polymer formed has Mw of 141,900 and Mw/Mn of 2.6.
Comparative Example 3
10 wt-% Trimethyl aluminum in isopentane (563 cm3) was measured into a
1-liter flask at OoC. 20 g of Davison'~ 948 silica having Loss-On-Ignition of
11.14%
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WO 96!01856 ~ 3 219 4 4 9 9 I ~J895105194
was added slowly to the TMA solution. After all the silica had been added, the
temperature was raised to 35oC and the isopentane solvent was removed under
vacuum to give a free-flowing powder. A sample of the powder (10 g) was
suspended in 50 cm3 heptane at 60oC, To this slurry was added a solution of
0.2925 g (nPentCp)2ZrC12 in toluene (35 cm3). Stirring was continued for 1.5 h
and then the solvent was removed under vacuum to give a free-flowing catalyst.
This catalyst was then used to polymerize ethylene as described in Example 1.
Comparative Example 4
10 wt-% Trimethyl aluminum in isopentane (844 cm3) was measured into a
I-liter flask at OoC. 20 g of Davison 948 silica having Loss-On-Ignition of
11.14%
was added slowly to the TMA solution. After all the silica had been added, the
temperature was raised to 35oC and the isopentane solvent was removed under
vacuum to give a free-flowing powder. A sample of the powder ( I O g) was
suspended in 60 cm3 heptane at 60oC. To this slurry was added a solution of
0.2925 g (t'~PentCp)2ZrC12 in toluene (35 cm3). Stirring was continued for 1.5
h
and then the solvent was removed under vacuum to give a free-flowing catalyst.
This catalyst was then used to polymerize ethylene as described in Example 1.
Eiamnle 5
I 0 wt-% Trimethyl aluminum in isopentane (2100 cm3 ) was measured into
a 3-liter flask at OoC. 150 g of Davison 948 silica having Loss-On-Ignition of
11.14% was added slowly to the TMA solution. After all the silica had been
added, the temperature was raised to 35oC and the isopentane solvent was
removed and replaced with heptane such that the concentration of solids in the
heptane slurry was 0.33 g/cm3. The support slurry was stored under a nitrogen
blanket for a period of 3400 h at ambient conditions in a 500 cc flask at
60oC. A
sample of the heptane slurry corresponding to l 0 g of support was measured
into a
500-cc flask at 60oC. To this slurry was added a solution of 0.2925 g
(nPentCp)2ZrC12 in toluene (3 5 cm3 ). Stirring was continued for 1 h and then
the
solvent was removed under vacuum to give a free-flowing catalyst. This
catalyst
was then used to polymerize ethyiene as described in Example 1. The polymer
formed has Mw of 142,200 and MwlMn of 2.5.
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Example 6
A sample (corresponding to 20 g of support) of the heptane treated-
support slurry described in example 5 above which had been stored under
nitrogen
blanket for a period of 360 h at ambient conditions was measured into a 500-cc
flask at 60~C. To this slurry was added a solution of 0.51 g (nPrCp)2ZrCl2 in
toluene (30 cm3). Stirring was continued for 1 h and then the solvent was
removed under vacuum to give a free-flowing catalyst. This catalyst was then
used
to polymerize ethylene as described in Example 1.
Example 7
A sample (corresponding to 20 g of support) of the heptane treated-
support slurry described in example 5 above which had been stored under
nitrogen
blanket for a period of 840 h at ambient conditions was measured into a 500-cc
flask at 60oC. To this slurry was added a solution of 0.51 g (nPrCp)2ZrC12 in
toluenea (30 cm3). Stirring was continued for 1 h and then the solvent was
removed under vacuum to give a free-flowing catalyst. This catalyst was then
used
to polymerize ethylene as described in Example 1.
Exam»le 8
:?0 A solution (3180 cm3) of 10 wt-% trimethyl aluminum in isopentane was
measured into a 5-liter flask at OoC. 150 g of Davison 948 silica having Loss-
On-
Ignition of 11.14% was added slowly to the TMA solution, After all the silica
had
been added, the temperature was raised to 35oC and the isopentane solvent was
removed and replaced with heptane such that the concentration of solids in the
heptane slurry was 0.33 g/cm3. After 312 h storage under ambient conditions
and
nitrogen blanket, a sample of the heptane slurry corresponding to 20 g of
support
was measured into a 500-cc flask at 60oC. To this slurry was added a solution
of
0.51 g (nPentCp)2ZrC12 in toluene (30 cm3). Stirring was continued for 1 h and
then the solvent was removed under vacuum to give a free-flowing catalyst.
This
catalyst was then used to polymerize ethylene as described in Example 1.
Examule 9
A sample (corresponding to 20 g of support) of the heptane treated
support slurry described in example 8 above which had been stored under
nitrogen
blanket for a period of 648 h at ambient conditions was measured into a 500-cc
AMENDED SHEET
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.
-15- ? 194499
flask at 60oC. To this slurry was added a solution of 0.51 g (nPrCp)2ZrC12 in
toluene (30 cm3). Stirring was continued for 1 h and then the solvent was
removed under vacuum to give a free-flowing catalyst. This catalyst was then
used
to polymerize ethylene as described in Example 1.
Eaample 10
A sample (corresponding to 20 g of support) of the heptane treated-
support slurry described in example 8 above which had been stored under
nitrogen
blanket for a period of 840 h at ambient conditions was measured into a S00-cc
flask at 60oC. To this slurry was added a solution of 0.51 g (nPrCp)2ZrC12 in
toluene (30 cm3). Stirring was continued for 1 h and then the solvent was
removed under vacuum to give a free-flowing catalyst. Thi ~ catalyst was then
used
to polymerize ethylene as described in Example 1.
From Table 1, Examples 1-5 were prepared using the same metallocene
(nPentyl Cp)2ZrC12 and Examples 6-10 were prepared using the same metallocene
(nPropyl Cp)2ZrCl2. Now referring to Examples 1-5, in Comparative Examples 1
4 the trimethyl aluminum/alumoxane loadings were increased from 1.2 to 6.0 and
as expected activity increased slightly as can be seen in the Table under the
heading
catalyst efficiency. However, Example 5 illustrates that at lower loadings
using the
aged activator of the invention catalyst efficiency is substantially increased
over the
comparative examples, especially over Comparative Example 2 having the same
loading. This increase over Comparative Example 2 is over 35%.
Examples 6-10 of the invention illustrate that equal loadings using the
activator of the invention aged for a different period of time results in a
significant
increase in catalyst activity as measured by catalyst efficiency. Examples 6
and 7
having the same Loading illustrate a 58% increase in efficiency by aging the
activator for a period of from 360 hours to 840 hours. Also, Examples 8-10 all
having the same loadings also illustrate the invention in that at 840 hours of
aging a
44% increase in catalyst efficiency is observed over aging the activator for
312
hours as in Example 8.
While the present invention has been described and illustrated by reference
to particular embodiments, it will be appreciated by those of ordinary skill
in the art
that the invention lends itself to variations not necessarily illustrated
herein. For
example, it is within the scope of this invention to mix at least two of the
catalysts
S of the invention or to use the catalyst of the invention with any other
catalyst or
AMENDED SNEEi'
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catalyst system known in the art, for example a traditional 2;iegler-Natta
catalyst or
catalyst system. Also the catalyst system of the invention can be used in a
single
reactor or in a series of reactors. For this reason, then, reference should be
made
solely to the appended claims for purposes of determining the true scope of
the
present invention.
TAB LE 1
Example TMA:HZO Length of Catalyst Efficiency
(mole ratio)Aging ~P~J(~C..T~ISOpsi)
hours (103.1 kPa)
Com arative 1.2 0 1271
1
Com arative 2.0 0 1207
2
Com arative 4.0 0 1305
3
Com arative 6.0 0 1473
4
5 2.0 3400 1728
6 2.0 360 1728
7 2.0 840 2723
8 3.0 312 1760
9 3 , 0 648 2240
10 3.0 840 2526
a~~w~~a s;-i~~'
