Note: Descriptions are shown in the official language in which they were submitted.
_ WO95/23816 21 81 2~9 PCT~S9S/02174
OLEFIN POLYMERIZATION CATALY8T8
This invention relates to olefin polymerization
catalysts, and particularly to catalysts for the
copolymerization of ethylene with a higher ~-olefin to
produce a material referred to as linear low density
polyethylene (LLDPE).
The polymerization of olefins, particularly ethylene,
is well known and has been a widely practiced commercial
art for many decades. Catalysts for such polymerization
are well known to include Ziegler type catalysts. In the
Ziegler type catalyst field, the catalyst is usually made
up of a transition metal compound and an alkyl aluminum,
which is used as a co-catalyst, sometimes with a magnesium
compound as well, usually on a suitable support.
In more recent times, it has been discovered that the
copolymerization of ethylene and higher olefins can be
catalyzed by special zirconium and/or hafnium compounds.
These compounds, called metallocenes, have been proposed
for use in this service in combination with aluminoxanes,
as co-catalysts, with both being deposited on a silica
substrate.
The invention provides a novel olefin polymerization
catalyst based on a metallocene catalyst and an aluminoxane
co-catalyst on a specially designed organic polymeric
substrate. This substrate comprises a resinous, cross-
linked, porous particulate material which is substantially
insoluble in either the reactant monomers or the product
polymers, or in common solvents which have been used as the
polymerization media in slurry or solution based
polymerization processes. The substrate is also
substantially insoluble in common solvents which are often
used in the production of the polymerization catalyst.
Accordingly, the invention resides in its broadest
aspect in a catalyst composition for copolymerizing
ethylene with an alpha olefin having 3 to l0 carbon atoms
comprising a metallocene compound activated with an
5~
wossn3816 PCT~S95/02174
-2-
aluminoxane and dispersed on the surface of a particulate
porous organic substrate comprising a crosslinked
polymerization product of styrene.
The chemically inert nature of the porous support
results in a purely physical dispersion of the
metallocene/aluminoxane deposited thereon to produce
catalysts with higher activity and which yield polymers
with narrower molecular weight distribution and higher
molecular weight than silica-supported catalysts.
A catalyst prepared on the inert porous organic
support of the invention does not require the use of
external methylaluminoxane co-catalyst solutions. As such,
it is ideally suited for gas phase polymerization reactors
and does not require high aluminoxane/metallocene ratios.
The substrate of the catalyst of this invention is not
a refractory material like silica, but rather is organic in
nature. It obtains its insolubility in the solvents set
forth above by reason of it having been made of a polymer
which is substantially cross-linked. Furthermore, the
degree of cross-linking imparts porosity to the organic
substrate, in contrast to nonporous (i.e., uncrosslinked)
organic substrates.
The cross-linking of the polymeric substrate may be by
reason of the inherent chemical composition of the polymer
components, such as by the presence of at least some
proportion of a monomer which has multiple functionality
which reacts in the particle forming polymerization to
create a cross-linked polymer particle during the initial
polymerization reaction. A preferred example of such a
monomer is divinyl benzene. Alternatively, the cross-
linking may be accomplished by means of a post
polymerization cross-linking process, such as bombardment
with high energy particles or peroxide treatment.
The preferred cross-linked porous polymer substrate is
made by a suspension polymerization process by producing a
copolymerization mixture comprising a water medium, as the
_ WO95123816 21 81 ~ ~ 9 PCT~S95/02174
continuous phase, having added thereto suitable proportions
of the desired monomers, e. g. styrene and divinyl benzene,
suspending agent(s), polymerization initiator(s), porogen
material(s), and any other component(s) which aid
suspension polymerization. The mixture is then subjected
to conventional suspension polymerization conditions,
whereby the co-monomers are polymerized and cross-linked;
and.the porogen-filled polymer particle products recovered.
After harvesting the suspension polymer particles
containing the porogen, this component is suitably removed,
usually by the use of solvents or steam. The thus made
particles are then dried to form free-flowing, porous
particles in which the pores are substantially empty.
Where the polymer particle is to be cross-linked after-
it has been made, as compared to cross-linking the polymer
during the initial polymerization, the initial suspension
polymerization is carried out in the manner set forth above
up to the stage where the porous resinous particles,
containing the porogen, are recovered. The post cross-
linking process should then be carried out while theporogen is still in place, and, after cross-linking has
been completed, the porogen is suitably removed in the same
manner as aforesaid.
Typical porogen materials include those materials
which are substantially inert with respect to the final
polymer particles, which will be incorporated within the
polymer particles, but which will not be chemically bound
to the particles. These porogens are exemplified by
substantially non-functional materials which are
substantially liquid under the conditions of pQlymerization
and recovery of the polymer particles, such as for example
mineral oil, heptane and toluene. The pore size, pore size
distribution, and the surface area of the resulting polymer
particles are, to a great extent, a function of the
particular porogen which is employed, the amount of porogen
WO95/23816 ~9 PCT~S95/02174
present during polymer particle formation, and the degree
of cross-linking in the polymer.
Reference is here made to the following journal
articles: "Macroreticular Resins. III. Formation of
Macroreticular Styrene-Divinyl Benzene Copolymers", K. A.
Kun and R. Kunin, J. Polymer Science: Part A-l, Vol. 6,
2689-2846 (1968); and "Styrene-Divinyl Benzene Copolymers.
Construction of Porosity in Styrene-Divinyl Benzene
Matrices", W. L. Sederel and G. J. DeJong, J. Applied
Polymer Science, Vol. 17, 2835-2846 (1973).
These articles describe a suitable, and even a
preferred, manner of making the cross-linked, porous,
resinous substrates of the catalyst systems of this
invention.
The resinous, cross-linked, porous particulate
substrate for use in conjunction with a metallocene olefin
polymerization catalyst suitably comprises a polymer which
is not only cross-linked, but is not readily susceptible to
deterioration under the conditions under which the catalyst
is applied thereto and/or the conditions of the use of the
supported catalyst in olefin polymerization. Addition
polymers are most well suited to use in this service.
Particularly the polymerization products of vinyl addition
reactions, preferably of aliphatic and/or aromatic vinyl
hydrocarbons, are well suited to this use. These include
poly (aliphatic) vinyl polymers, poly (aromatic) vinyl
polymers, poly divinyl polymers, copolymers of these
monomer categories, and the like. Hydrocarbonaceous
polymers which are cross-linked or cross-linkable are the
preferred composition of the substrate particles of this
invention.
Cross-linked aromatic addition polymers are the
preferred hydrocarbonaceous polymers for use in this
invention. The most preferred resinous materials are
styrene-divinyl benzene co-polymers. When this polymer
system is used, the pore size of the resulting polymer
_ WO95/23816 21 81 2S 9 PCT~S95/02174
particles is not only a function of the particular porogen
which has been selected, but is also a function of the
proportion of divinyl benzene which is employed. In this
regard, it should be noted that commercial divinyl benzene
is usually a mixture of isomers and saturated ethylene
derivatives. It most commonly contains about 50% of the
desired para isomers. When considering the proportion of
the copolymer which is to be made up of divinyl benzene, it
is usually only the para isomer which engages in the
polymerization, and therefore, only the amount of this
isomer should be considered in determining the proportions
of this monomer.
In one preferred aspect of this invention, in which
the porous substrate has substantially no surface activity,
the proportion of styrene monomers comprises up to 94
weight per cent and the remainder (considering only the
para isomer) divinyl benzene. This is sufficient to make a
cross-linked polymer product. The preferred proportion of
styrene monomer in this system is 60 to 80 weight per cent.
In addition to the monomer or monomers which are
needed to form the fundamental resinous particle of the
support, it is also possible to provide additional co-
monomers in the co-polymerization monomer mixture. These
additional co-monomers may satisfy and provide certain
additional functions as needed and they then may become
incorporated within the resinous polymer product and exert
an effect on the operation of the catalyst.
In one such embodiment, the additional monomers
containing reactive groups which are not substantially
reactive with the strictly hydrocarbon basic monomers, are
included in the monomer mixture which is co-polymerized to
produce the desired substrate particle, and are
copolymerized along with the basic monomers to form the
catalyst substrate particles. These pendant additional
monomers remain as unreacted functional groups after the
WO95/23816 g PCT~SgS/02174
formation of the cross-linked resinous particle~ and are
desirably co-polymerized directly into the cross-linked co-
polymer in a manner such that their "non-reactive"
functional groups remain active on the surface of the
resultant resinous substrate particles. In this condition,
they are readily available for further reaction after the
crosslinked resinous catalyst substrate particle has been
formed.
The additional functional co-monomers preferably have
the same fundamental structure and chemistry as the co-
monomers which are being co-polymerized to form the basic
porous particle of this invention. Thus, in the situation
where aromatic monomers, like styrene and divinyl benzene,
are the basic polymerization building blocks, the added
functional co-monomer should also preferably have a
styrene, or at least an aromatic type, core structure.
Moreover, it is important that the functional group of
the additional monomer is substantially inert during the
polymerization of the basic monomers. Thus, if the cross-
linked polymer which will form the fundamental particlesubstrate for use in this invention is an olefin addition
polymer, the added functional group should be one which
does not readily react with olefinic unsaturation under the
polymerization conditions. On the other hand, if the
fundamental polymer of the particulate substrate is a
condensation polymer, such as a polyester or a polyamide,
the additional functional group may be an olefinic
unsaturation, provided that it does not react to any
appreciable extent in the polymerization condensation
reaction. In addition, the polymerization conditions
should be taken into account when selecting the monomers
being reacted so as to insure that only those desired
functional substituents react in the polymerization, only
those desired portions of the polymer react in the cross-
linking, and those desired functional groups which need to
_ WO95/23816 1 81 2S9 PCT~Sg5/02174
be retained do not react at all in the basic process ofproducing the crosslinked resinous porous particle.
~ Suitable additional monomers for use in this
embodiment include acrylic and methacrylic acids and
esters, vinyl ethers, such as methyl vinyl ether, vinyl
esters, such as vinyl acetate, vinyl halides, such as vinyl
chloride, acrylonitriles, alkylene glycol di-acrylates and
methacrylates, such as ethylene and propylene glycol di-
acrylates and methacrylates, hydroxy terminated unsaturated
acids and esters, such as ~ hydroxy acrylic acid and esters
thereof, halo substituted aromatic olefins, such as chloro-
styrene or chloro-divinyl benzene, hydroxy substituted
styrene, p-acetoxystyrene or divinyl benzene, vinyl
toluene, vinyl pyridine, vinyl benzyl halides, such as
vinyl, benzyl chloride, and the like, are quite useful. It
is within the scope of this invention to use between l and
30 weight percent of one or more additional monomers
con~;n;ng at least one pendant functional group in
admixture with the basic monomer(s). In one aspect of this
invention, where the basic monomers are styrene and divinyl
benzene, this proportion of added monomer is copolymerized
with a mixture comprising up to about 94 % styrene and the
remainder, that is at least about 6 %, divinyl benzene.
The use of the additional functional monomer provides
another degree of freedom in controlling the properties of
the ethylene polymerization products produced using
catalysts of the metallocene/aluminoxane/resinous substrate
type. Thus, where the pendant functional group is an
acetoxy group; where the catalyst comprises a zirconocene,
an aluminoxane, and an aluminum hydrocarbyl on a
crosslinked, porous, resinous styrene-divinyl benzene
substrate; where the catalyst has been made in
substantially the same way and with the same proportions of
constituents; and where the ethylene polymerization has
been carried out under the substantially the same
conditions, the polymer product produced can have a melt
WO9S/23816 ~ PCT~S95/02174
index about three (3) orders of magnitude higher than where
the catalyst substrate does not have a functional monomer
copolymerized therewith.
In one preferred embodiment of the invention, in which
the resinous substrate has no surface functionality, the
substrate is a cross-linked styrene-divinyl benzene co-
polymer comprising about 80 weight percent styrene and 20
weight per cent divinyl benzene.
In an alternative preferred formulation, in which the
substrate has surface functionality, the divinyl benzene
comprises about 30 % by weight of the crosslinked resinous
substrate, the styrene comprises about 55 %, and functional
added monomer is p-acetoxy styrene which comprises about 15
% thereof.
The porosity of the styrene polymer support particles
of the invention is preferably controlled so that the pore
size is between lO0 and 1050 Angstrom. In fact it has been
found that in the catalyst system of this invention, if all
of the polymerization conditions are kept relatively
constant, the molecular weight of the product co-polymer
decreases as a function of decreasing average pore
diameter. Therefore, in order to use the catalyst system
of this invention to produce relatively low molecular
weight ethylene co-polymerization products, that is
products having melt indices of at least about lO,
preferably at least about 15, it is preferred that the
average pore diameter of the resinous substrate is not more
than 300 A, preferably not more than 200 A. The particle
size of the carrier substrate preferably ranges from lO to
lO0 microns, more preferably 30 to 50 microns.
The aluminoxanes used in the catalyst of the invention
comprise oligomeric linear and/or cyclic alkylaluminoxanes
represented by the formula:
_ WOsS/238l6 81 2~ ~ 9 PCT~S95/02174
R-(Al(R)-O)n-AlR2 for oligomeric, linear aluminoxanes and
(-Al(R)-0-)~ for oligomeric cyclic aluminoxanes wherein n
` is 1-40, preferably 10-20, m is 3-40, preferably 3-20 and R
is a C1-C8 alkyl group, preferably a C1-C3 alkyl, and most
preferably methyl. MA0 is a mixture of oligomers with a
very wide distribution of molecular weights and usually
with an average molecular weight of about 1200. MA0 is
typically kept in solution in toluene. The aluminoxane is
preferably present in an amount to provide O.l to 20 mmol
Al/gram of support.
The metallocene compound used in the catalyst of the
invention has the formula Cp~Bp in which Cp is an
unsubstituted or substituted cyclopentadienyl group, M is
zirconium or hafnium, preferably zirconium, and A and B
belong to the group including a halogen atom, hydrogen or
an alkyl group in the formula, m+n+p = the balance of M, m
is at least one, preferably 2, and each of n and p may be
0, l, 2 or 3. In the above formula of the metallocene
compound, where Cp is a substituted cyclopentadienyl group,
the or each substituent is preferably a straight or
branched chain C,-C6 alkyl group. The cyclopentadienyl group
can be also a part of a bicyclic or a tricyclic moiety such
as indenyl, tetrahydroindenyl, fluorenyl or a partially
hydrogenated fluorenyl group, as well as a part of a
substituted bicyclic or tricyclic moiety. In the case when
m in the above formula of the metallocene compound is equal
to 2, the cyclopentadienyl groups can be also bridged by
polymethylene or dialkylsilane groups, such as -CH2-, -CH2-
CH2-, -CR'R"- and -CR'R"-CR'R"- where R' and R" are short
alkyl groups or hydrogen, -Si(CH3)2-, Si(CH3)2-CH2-CH2-
Si(CH3) 2- and similar bridge groups. If the substituents A
and B in the above formula of the metallocene compound are
alkyl groups, they are preferably straight-chain or
branched Cl-C8 alkyl groups, such as methyl, ethyl, n-
propyl, isopropyl, n-butyl, isobutyl, n-pentyl, n-hexyl or
n-octyl.
WO95/~816 ~ ; PCT~S95/02174
'l -10- `
Suitable metallocene compounds include bis(cyclo-
pentadienyl)metal dihalides, bis(cyclopentadienyl)metal
hydridohalides, bis(cyclopentadienyl)metal monoalkyl
monohalides, bis(cyclopentadienyl)metal dialkyls and
bis(indenyl)metal dihalides wherein the metal is zirconium
or hafnium, halide groups are preferably chlorine and the
alkyl groups are C1-C6 alkyls. Illustrative, but non-
limiting examples of metallocenes include
bis(cyclopentadienyl) zirconium dichloride,
bis(cyclopentadienyl)hafnium dichloride,
bis(cyclopentadienyl)zirconium dimethyl,
bis(cyclopentadienyl) hafnium dimethyl,
bis(cyclopentadienyl)zirconium hydridochloride,
bis(cyclopentadienyl)hafnium hydridochloride,
bis(pentamethylcyclopentadienyl)zirconium dichloride,
bis(pentamethylcyclopentadienyl)hafnium dichloride, bis(n-
butylcyclopentadienyl)zirconium dichloride,
cyclopentadienyl-zirconium trichloride,
bis(indenyl)zirconium dichloride, bis(4,5,6,7-tetrahydro-l-
indenyl)zirconium dichloride, and ethylene-[bis(4,5,6,7-
tetrahydro-l-indenyl)] zirconium dichloride. The
metallocene compounds can be used as solutions in aromatic
hydrocarbons.
The preferred metallocene is cyclopentadienyl
zirconium chloride in a preferred proportion of 0.025 to
0.65 mmol/gram of support.
The catalyst conveniently also comprises a hydrocarbyl
aluminum compound, preferably an alkyl aluminum, wherein
the alkyl group has up to 8 carbon atoms, preferably up to
6 carbon atoms, and more preferably a branched alkyl group
such as isoprenyl or isobutyl, most preferably isoprenyl.
The hydrocarbyl aluminum compound is preferably present in
an amount to provide O.l to 6 mm Al/gram of support.
To produce the catalyst of the invention, the
metallocene and aluminoxanes are conveniently dissolved in
- woss/23816 81 2 s~ 11 PCT~S95/02174
a solvent, in which the substrate particles are insoluble,
such as toluene, and the solutuion is then introduced into
contact with the empty, porous cross-linked polymer
particles and absorbed onto the surface thereof. Catalyst
preparation is undertaken under anhydrous conditions and in
the absence of oxygen. Solvent may be removed from the
impregnated pores of the carrier material by heating and/or
under a vacuum or purged with heating in an inert gas, such
as nitrogen. Upon drying, the thus produced catalysts are
then ready for use in a polymerization process.
Another advantage of this invention is the preparation
of metallocene/aluminoxane catalysts on inert porous
substrates that do not require the presence of external
methylaluminoxane co-catalyst. This imparts several
advantages to this catalyst system. Nonrequisite use of
methylaluminoxane co-catalyst makes these catalysts ideally
suited for gas phase polymerizations, since
methylaluminoxane co-catalyst solutions have resulted in
serious process problems in fluid-bed (gas phase) reactors.
Another advantage is more prudent use of eyp~cive
methylaluminoxane since much lower methylaluminoxane to
metallocene ratios are required for the catalyst system of
the invention.
The invention will now be more particularly described
with reference to the following examples in which all parts
and percentages are by weight unless specifically stated to
be on some other basis.
EXAMPLE 1
2.5 grams of a cross-linked co-polymer of 80% styrene
and 20% divinyl benzene, which had an average pore diameter
of 1050 Angstroms, was dried under vacuum at 100C for 12
hours. To the dried co-polymer beads, 50 cc of toluene was
added and the slurry mixture heated to 70C with stirring.
Then 2.1 cc of a 25% solution of isoprenyl aluminum in
hexane was added. After stirring for 10 minutes, 1.7 cc of
WO ~nu816 ~ -12- pCT~S9S/02l74
a 12~ solution (5.8 wt% Al) of methylaluminoxane in toluene
was added. After stirring for 30 minutes, a solution of
0.05 g Cp2ZrCl2 diæsolved in 10 cc toluene was added. The
solvent was then removed by nitrogen purging at 80-C for
several hours until dry. The resulting catalyst was
composed of 0.068 mmol of bis(cyclopentadienyl) zirconium
dichloride/gram of support; 1.3 mmol, based on aluminum, of
methylaluminoxane/gram of support; and 1.0 mmol, based on
aluminum, of isoprenyl aluminum/gram of support.
Ethylene Polymerization
Polymerization was performed in a 4 liter slurry
autoclave reactor equipped with propeller stirrer, external
heating jacket for temperature control, a catalyst, and co-
catalyst inlet and a regulated supply of dry nitrogen,
ethylene, and l-hexene. The internal walls of the reactor
were dried by baking at 85C for one hour under a slow
nitrogen stream. After cooling to ambient temperature,
1.45 liters of dry hexane and 0.25 liter of l-hexene were
delivered to the reactor under a steady nitrogen stream.
Then 2.0 cc of a 12% solution (5.8 wt.% Al) of methyl-
aluminoxane in toluene was injected into the reactor. The
reactor was heated to 85C with stirring at 900 rpm, filled
with ethylene until a total pressure of 1135 kPa (150 psig)
was obtained and then 0.11 g of the catalyst was injected
into the reactor using a hexane filled bomb containing
1480 kPa (200 psig) ethylene. The polymerization reaction
was allowed to proceed for 60 minutes. A yield of 112
grams of co-polymer product was obtained. The polymer had
a melt index (I2) of 1.9 g/10 min. The productivity of the
catalyst was 810 g/g catalyst/hr/100 psi ethylene. The
melt flow ratio (MFR=I2JI2) of the co-polymer was 19.
COMPARATIVE EXAMPLE 1
A solid catalyst was prepared in the same way as in
Example 1 except Davison 955 silica (calcined for 12 hours
- WO95/~816 1 2S9 -13- PCT~S95/02174
at 600C) instead of the cross-linked polymer was used as
the solid support. The silica support had an average pore
diameter of 200 Angstroms. Polymerization was carried out
as in Example 1. The co-polymer product had a melt index
(I2) of 34 g/10 min. The productivity of the catalyst was
510 g/g catalyst/hr/100 psi ethylene. The melt flow ratio
(MFR=I21I2) of the co-polymer was 17.
COMPARATIVE EXAMPLE 2
A solid catalyst was prepared in the same way as in
Example 1 except nonporous spherical (1% cross-linked)
polysLy~ene (#200-#400, a product of Eastman Kodak Co.) was
used as the solid support. The resulting catalyst was
highly agglomerated and could not be fed into the reactor.
EXAMPLE 2
A solid catalyst was prepared in the same way as in
Example 1 except the cross-linked polymer used as the solid
support had an average pore diameter of 110 Angstroms.
Polymerization was carried out as in Example 1. The co-
polymer product had a melt index (I2) of 19 g/10 min. The
productivity of the catalyst was 1240 g/g catalyst/hr/100
psi ethylene.
EXAMPLE 3
A solid catalyst was prepared in the same way as in
Example 1 except the cross-linked polymer used as the solid
support had an average pore diameter of 260 Angstroms.
Polymerization was carried out as in Example l. The co-
polymer product had a melt index (I2) of 16 g/10 min. The
productivity of the catalyst was 1380 g/g catalyst/hr/100
psi ethylene.
EXAMPLE 4
One gram of a cross-linked polymer of 80% styrene and
20% divinyl benzene was dried under vacuum at 100C for 12
~'~
W095/238i6 ~ PCT~S95/02174
hours. The dried co-polymer was slurried in 10 ml heptane,
and 1.3 ml of 15% trimethylaluminum in heptane was added.
After stirring for one hour at 70C, the solvent was
removed by nitrogen purging at 70C for one hour. The
trimethylaluminum-treated beads were reslurried in 10 ml
toluene, to which a solution of 0.03 gram of bis(n-
butylcyclopentadienyl) zirconium dichloride in 2.7 ml of
15.8 wt.% Al methylaluminoxane in toluene was added with
stirring at 70C for 30 minutes. Solvent was removed by
nitrogen purging at 70C for 1 hour followed by vacuum
drying at 70C for 2 hours. The resulting catalyst was
composed of 0.075 mmol of bis(cyclopentadienyl) zirconium
dichloride/gram of support; 15.0 mmol, based on aluminum,
of methylaluminoxane/gram of support; 1.9 mmol, based on
aluminum, of trimethylaluminum/gram of support.
Ethylene Polymerization
Polymerization was performed in a 4 liter slurry
autoclave reactor equipped with propeller stirrer, external
heating jacket for temperature control, a catalyst, and co-
catalyst inlet and a regulated supply of dry nitrogen,ethylene, and l-hexene. The internal walls of the reactor
were dried by baking at 85C for one hour under a slow
nitrogen stream. After cooling to ambient temperature,
1.50 liters of dry heptane and 0.35 liter of l-hexene were
delivered to the reactor under a steady nitrogen stream.
Then 1.7 cc of a 15% solution of trimethylaluminum in
heptane was injected into the reactor. The reactor was
heated to 80C with stirring at 900 rpm, filled with
ethylene until a total pressure of 1340 kPa (180 psig) was
obtained, and then 0.19 g of the catalyst was injected into
the reactor using a heptane filled bomb containing 1620 kPa
(220 psig) ethylene. The polymerization reaction was
allowed to proceed for 45 minutes. A yield of 238 grams of
co-polymer product was obtained. The polymer had a melt
index (I2) of 0.52 g/10 min. The productivity of the
21 81 25~
_ WO9S/23816 -15- PCT~S95/02174
catalyst was 920 g/g catalyst/hr/100 psi ethylene. The
melt flow ratio (MFR=I2l/I2) of the co-polymer was 17.
COMPARATIVE EXAMPLE 3
A solid catalyst was prepared in the same way as in Example
4 except PQ 988 silica (calcined for 12 hours at 600C)
instead of the cross-linked polymer used as the solid
support. Polymerization was carried out as in Example 4.
The co-polymer product had a melt index (I2) of 0.38 g/10
min. The productivity of the catalyst was 310 g/g
catalyst/hr/100 psi ethylene. The melt flow ratio
(MFR=I2,/I2) of the co-polymer was 22.
COMPARATIVE EXAMPLE 4
A solid catalyst was prepared in the same way as in
Example 4 except nonporous spherical (1% cross-linked)
polystyrene (#200-#400, a product of Eastman Kodak Co.) was
used as the solid support. The resulting catalyst was
highly agglomerated and could not be fed into the reactor.
EXAMPLE 5
Five grams of a cross-linked polymer of 55% styrene,
30% divinyl benzene, and 15% p-acetoxy styrene, where the
acetoxy groups of the terpolymer were hydrolyzed to hydroxy
groups with hydrazine, were dried under vacuum at 110C for
12 hours. To the dried copolymer beads, 50 cc of toluene
was added and the slurry mixture heated to 70C with
stirring. Then 4.2 cc of a 25% solution of isoprenyl
aluminum in hexane was added. After stirring for 10
minutes, 3.4 cc of a 12% solution (5.8 wt% Al) of
methylaluminoxane in toluene was added. After stirring for
30 minutes, a solution of 0.10 g Cp2ZrCl2 dissolved in 10 cc
toluene was added. The solvent was then removed by
nitrogen purging at 80C for several hours until dry. The
resulting catalyst was composed of 0.068 mmol of
bis(cyclopentadienyl)zirconium dichloride/gram of support;
wo 95~23816 9 PCT~S95/02174
~S -16-
l.3 mmol, based on aluminum, of methylaluminoxane/gram of
support; and l.0 mmol, based on aluminum, of isoprenyl
aluminum/gram of support.
Ethylene Polymerization
Polymerization was performed as in Example l to
produce after 60 minutes a yield of 97 grams of co-polymer
product was obtained. The polymer had a melt index (I2) of
430 g/l0 min. The productivity of the catalyst was 490 g/g
catalyst/hr/l00 psi ethylene.
COMPARATIVE EXAMPLE 5
A solid catalyst was prepared in the same way as in
Example 5 except Davison 955 silica (calcined overnight at
600-C) instead of the cross-linked polymer was used as the
solid support. Polymerization was carried out as in
Example l. The co-polymer product had a melt index (I2) of
34 g/l0 min. The productivity of the catalyst was 500 g/g
catalyst/hr/l00 psi ethylene. The melt flow ratio
(MFR=I21I2) of the co-polymer was 17.
COMPARATIVE EXAMPLE 6
A solid catalyst was prepared in the same way as in
Example 5 except the cross-linked polymer used as the solid
support was composed of a copolymer of 80% styrene and 20%
divinyl benzene. Polymerization was carried out as in
Example l. The co-polymer product had a melt index (I2) of
l.s g/l0 min. The productivity of the catalyst was 810 g/g
catalyst/hr/l00 psi ethylene.
COMPARATIVE EXAMPLE 7
A solid catalyst was prepared in the same way as in
Example 5 except spherical non-porous (1% cross-linked)
polystyrene (#200-#400, a product of Eastman Kodak Co.) was
used as the solid support. The resulting catalyst was
highly agglomerated and could not be fed into the reactor.
_ WO95123816 1 81 2 S9 -17- - - PCT~S95/02174
EXAMPLE 6
A solid catalyst was prepared in the same way as in
Example 5 except the cross-linked polymer used as the solid
support was composed of a terpolymer of 55% styrene, 30%
divinyl benzene, and 15% p-acetoxy stryene. Polymerization
was carried out as in Example 1. The co-polymer product
had a melt index (I2) of 1500 g/10 min. The productivity
of the catalyst was 560 g/g catalyst/hr/100 psi ethylene.
EXAMPLE 7
One gram of a cross-linked polymer of 55% styrene, 30%
divinyl benzene, and 15% p-acetoxy styrene, where the
acetoxy groups of the terpolymer were hydrolyzed to hydroxy
groups with hydrazine, were dried under vacuum at 110C for
12 hours. The dried copolymer was slurried in about 20 ml
heptane and 1.4 ml of 15% trimethylaluminum in heptane was
added. After stirring for one hour at 70-C, the solvent
was removed by nitrogen purging at 70C for one hour. The
trimethylaluminum-treated beads were reslurried in about 20
ml toluene, to which a solution of 0.030 gram of bis(n-
butylcyclopentadienyl)zirconium dichloride in 3.2 ml of13.7 wt% Al methylaluminoxane in toluene was added with
stirring at 70C for 30 minutes. Solvent was removed by
nitrogen purging at 70C for 2 hours, after which free
flowing beads were obtained. The resulting catalyst was
composed of 0.075 mmol of bis(cyclopentadienyl)zirconium
dichloride/gram of support; 15.0 mmol based on aluminum, of
methylaluminoxane/gram of support; 1.9 mmol, based on
aluminum, of trimethyl-aluminum/gram of support.
Ethylene Polymerization
Polymerization was performed in a 4 liter slurry
autoclave reactor equipped with propeller stirrer, external
heating jacket for temperature control, a catalyst and co-
catalyst inlet and a regulated supply of dry nitrogen,
ethylene, and l-hexene. The internal walls of the reactor
WO95/23816 PCT~S95/02174
~ 9 -18-
were dried by baking at 85C for one hour under a slow
nitrogen stream. After cooling to ambient temperature,
1.50 liters of dry hexane and 0.35 liter of 1-hexene were
delivered to the reactor under a steady nitrogen stream.
Then 1.7 cc of 15% solution of trimethyl aluminum in
heptane was injected into the reactor. The reactor was
heated to 80-C with stirring at 900 rpm, filled with
ethylene until a total pressure of 1340 kPa (180 psig) was
obtained, and then 0.12 g of the catalyst injected into the
reactor using a hexane filled bomb containing 1620 kPa (220
psig) ethylene. The polymerization reaction was allowed to
proceed for 60 minutes. A yield of 199 grams of co-polymer
product was obtained. The polymer had a melt index (I2) of
1.0 g/10 min. The productivity of the catalyst was 1000
g/g catalyst/hr/100 psi ethylene. The melt flow ratio
(MFR=I2,I2) of the co-polymer product was 15.
- COMPARATIVE EXAMPLE 8
A solid catalyst was prepared in the same way as in
Example 7 except PQ 988 silica (calcined for 12 hours at
600-C) instead of the cross-linked polymer used as the
solid support. Polymerization was carried out as in
Example 7. The co-polymer product had a melt index (I2) of
0.38 g/10 min. The productivity of the catalyst was 310
g/g catalyst/hr/100 psi ethylene. The melt flow ratio
(MFR=I2JI2) of the co-polymer was 22.
COMPARATIVE EXAMPLE 9
A solid catalyst was prepared in the same way as in
Example 7 except a copolymer of 80% styrene and 20% divinyl
benzene was used as the solid support. Polymerization was
carried out as in Example 7. The co-polymer product had a
melt index tI2) of 0.52 g/10 min. The productivity of the
catalyst was 920 g/g catalyst/hr/100 psi ethylene. The
melt flow ratio (MFR=I2,/I2) of the co-polymer was 17.
_ WO95/23816 12$g -19- PCT~S95/02174
COMPARATIVE EXAMPLE l0
A solid catalyst was prepared in the same way as in
Example 7 except nonporous 1% cross-linked polystyrene
(#200-#400, a product of Eastman Kodak Co.) was used as the
solid support. The resulting catalyst was highly
agglomerated and could not be fed into the reactor.
