Note: Descriptions are shown in the official language in which they were submitted.
1~68753
1 This invention relates to a transition metal containing
2 supported catalyst component useful in combination with a co-catalyst
3 for the polymerization and copolymerization of olefins and particu-
4 larly useful for the polymerization of ethylene and copolymerization
of ethylene with l-olefins having 3 or more carbon atoms such as, for
6 example, propylene, i-butene, l-butene, l-pentene, l-hexene, l-octene,
7 dienes such as butadiene, 1,7-octadiene and 1,4-hexadiene. The inven-
8 tion further relates to a heterogeneous catalyst system comprising the
9 transition metal containing supported catalyst component and as a
co-catalyst, an alumoxane. The invention further generally relates to
11 a process for polymerization of ethylene alone or with other l-olefins
12 or diolefins in the presence of a catalyst system comprising the-sup-
13 ported transition metal-containing catalyst component and an alumoxane.
14 Description of the Prior ~rt
Traditionally, ethylene and l-olefins have been polymerized
16 or copolymerized in the presence of hydrocarbon insoluble catalyst
17 systems comprising a transition metal compound and an aluminum alkyl.
18 More recently, active homogeneous catalyst systems comprising a
19 bis-(cyclopentadienyl)titanium dialkyl or a bis(cyclopentadienyl)- :
zirconium dialkyl, an aluminum trialkyl and water have been found to
21 be useful for the polymerization of ethylene. Such catalyst systems
22 are generally referred to as Ziegler-type catalvsts
23 German Patent Application 2,608,86.~ (laid open August 9, 1977)
24 discioses the use of a
2s catalyst system for the polymerization of etnylene consisting of bis
26 (cyclopentadienyl) titanium dialkyl, aluminum trialkvl ~n~ water
27 German Patent Application 2,60~3,933 (laid open August 9, 1977)
28 discloses an ethylene
29 polymerization catalyst system consisting of zirconium metallocenes of
the general formula (cyclopentadienyl)nZrY4 n wl~erein n stands
31 for a number in the range of 1 to 4, Y for R, CH2AlR2, CH2CH2AlR2 and
32 CH2CH(AlR2)2, wherein R stands for alkyl or metallo alkyl, and an
33 aluminum trialkyl co-catalyst and water.
34 European Patent Application No. 0035242 (published September 9,
1981) discloses a process
36 for preparing ethylene and atactic propylene polymers in the presence
37 of d halogen-free ~iegler catalyst system comprising (1) a cyclo-
38 pentadienyl compound of the formul3 (cyclopentadielyl)nlleY4 n in
39 which n is an integer from 1 to 4, Me is~-a transition metal,
especially zirconium, and Y is either hydrogen, a Cl-C5 alkyl or
41 r.::t2110 alkyl group or a radical llaving t~e follo~:i,ng general forlrl!la
~68753
-- 2 --
1 CH2AlR2, CH2CH2AlR2 and CH2CH(AlR2)2 in which R represents a
2 Cl-C5 alkyl or metallo alkyl group, and (2) an alumoxane.
3 Additional teachings of homogeneous c,ata~lyst systems com-
4 prising a metallocene and alumoxane are found in 7J.S. 4,404,344
issued Septe~ber 13, 1983 o~ Sinn et al.
7 In "Molecular Weight Distribution and Stereoregularity Of
8 Polypropylenes Obtained With Ti(OC4Hg)4tAl(C2H5)3 Catalyst System";
9 Polymer, Pg. 469-471, 1981, Vol. 22, April, Doi, et al disclose
propylene polymerization with a catalyst which at about 41C obtains a
11 soluble catalyst and insol~ble cata7yst fraction, one with
12 "homogeneous catalytic centres" and the other with "heterogeneous
13 catalytic centres". The polymerization at that temperature obtains
14 polypropylene having a bimodal molecular weight distribution.
It is also ~nown to produce polymer blends by polymerizing
16 two or more polymerizable materials in two or more reactors arranged
17 in series. In accordance with such methods, a polymerizate is
18 produced in a first reactor which first polymerizate is passed to a
19 second reactor wherein a second polymerizate is produced thereby
obtaining a blend of the first and second polymerizates.
21 An advantage of the metallocene-alumoxane homogeneous
22 catalyst system is the very high activity obtained for ethylene
23 polymerization. Another significant advantage is, unlike olefin
24 polymers produced in the presence of conventional heterogeneous
Ziegler catalysts, terminal unsaturation is present in polymers
26 produced in the presence of these homogeneous catalysts. Never-
27 theless, the catalysts suffer from a disadvantage, that-is, the ratio
28 of alumoxane to metallocene is high, for example, in the order of
29 1,000 to 1 or greater. Such voluminous amounts of alumoxane would
require extensive treatment of polymer product obtained in order to
31 remove the undesirable aluminum. Another disadvantage of the
32 homogeneous catalyst system is that the polymer product produced
33 therefrom manifests small particle size and low bulk densitv.
34 In u.s. 4,530,914 issued July 23, 1985, a
homogeneous catalyst system comprising two different metallocenes for
36 use in producing polyolefins having a broad molecular weight
3~ distribution and/or multi-modal molecular weight distribution is
38 desCri bed.
1~875;3
--3--
Other teachings are found in U.S. 4,522,982 issued
June 11, 1985. James C. W.
Chien, in "Reduction of Ti(IV) Alkyls in Cab-0-Sils Surfaces", Jrnl.
of Catalysis 23, 71(1971); Dag Slotfeldt-Ellingsene et al. in
"Heterogenization of Homogeneous Catalysts", Jrnl. Molecular
Catalysis, 9, 423 (1980)disclose a supported titanocene in combination
with alkyl aluminum halides as poor catalysts for olefin
polyrnerization.
It would be-highly desirable to provide a metallocene based
catalyst which is comrnercially useful for the polymerization of
olefins wherein the aluminum to transition metal ratio is reduced
compared with the known homogeneous systems, to provide a poly-
merization catalyst system which produces polymer product having
improved particle size and bulk density, and to prov~ide a catalyst
system which evidences improved comonomer incorporation in the
production of, for example, linear low density polyethylene (LLDPE).
It is particularly desirable to provide a catalyst system capable of
producing polymers having a varied range of molecular weight
distributions and/or compositional distributions.
Su1mary of the Invention
In accordance with the present invention, a catalyst system
comprising a metallocene supported catalyst component and an alumoxane
co-catalyst is provided for olefin polymerization, and particularly
for the production of linear low, medium and high density poly-
ethylenes and copolymers of ethylene with alpha-olefins having 3 or
more carbon atoms (C3-C18) and/or diolefins having up to 18 carbon
atoms.
The supported catalyst component provided in accordance with
one embodiment of this invention, comprises the product obtained by
contacting at least one metallocene and a support material thereby
providing a supported (rnulti)metallocene-olefin polymerization
catalyst component.
8'~5;~
1 In accordance with another embodiment of the invention, a
2 catalyst system comprising a supported (multi) metallocene and an
3 alumoxane is provided which will polymerize olefins at commercially
4 respectable rates without an objectionable excess of alumoxane as
required in the homogenous system.
6 In yet another embodiment of this invention there is provided
7 a process for the polymerization of ethylene and other olefins, and
8 particularly homopolymers of ethylene and copolymers of ethylene and
9 higher alpha-olefins and/or diolefins in the presence of the new
catalyst system. The process, by means of the catalyst, provides the
11 capability of producing polymers having a varied range of molecular
12 weight distributions, i.e., from narrow molecular weight distribution
13 to a broad molecular weight distribution and/or multi-modal molecular
14 weight distribution. The process also provides the capability of
producing reactor blends.
16 Reactor blends are mixtures of two or more (co)polymers of
17 different monomer composition and different physical properties
18 (density, melting point, etc.) produced simultaneously in a single
19 polymerization reactor.
The metallocenes employed in the production of the supported
21 catalyst component are organometallic coordination compounds which are
22 cyclopentadienyl derivatives of a Group 4b, 5b, or 6b metal of the
23 Periodic Table (56th Edition of Handbook of Chemistry and Physics, CRC
24 Press [1975]) and include mono, di and tricyclopentadienyls and their
derivatives of the transition metals. Particularly desirable are the
26 metallocenes of Group 4b metals such as titanium and zirconium. The
27 alumoxanes employed as the co-catalyst with the metallocenes are
28 themselves the reaction products of an aluminum trialkyl with water.
29 The alumoxanes are well known in the art and comprise
oligomeric, linear and/or cyclic alkyl alumoxanes represented by the
31 formulae:
1.
3753
1 (I) R-(Al-O)n-AlR2 for oligomeric, linear alumoxanes, and
2 R
3 (II) (-Al-O-)m for oligomeric, cyclic alumoxanes,
4 R
wherein n is l-40, preferably l-20, m is 3-40, preferably 3-20 and R
6 is a Cl-C8 alkyl group and preferably methyl. Generally, in the
7 preparation of alumoxanes from, for example, trimethylaluminum and
8 water, a mixture of linear and cyclic compounds is obtained.
9 The alumoxanes can be prepared in a variety of ways.
Preferably, they are prepared by contacting water with a solution of
11 aluminum trialkyl, soch as, for example, trimethylaluminum, in a
12 suitable organic solvent such as benzene or an aliphatic hydrocarbon.
13 For example, the aluminum alkyl is treated with water in the form of a
14 moist solvent. In a preferred method, the aluminum alkyl, such as
trimethylaluminum, can be desirably contacted with a hydrated salt
16 such as hydrated ferrous sulfate. The method comprises treating a
17 dilute solution of trimethylaluminum in, for example, toluene with
18 ferrous sulfate heptahydrate.
19 PREFERRED EMBODIMENTS
Briefly, the supported (multi) transition metal containing
21 catalyst component of the present invention is obtained by contacting
22 at least one metallocene with a solid porous support material. The
23 supported product is employed as the transition metal-containing
24 catalyst component for the polymerization of olefins
Typically, the support can be any solid, particularly porous
~6 supports such as talc or inorganic oxides, or resinous support
27 materials such as a polyolefin. Preferably, the support material is a
28 inorganic oxide in finely divided form.
29 Suitable inorganic oxide materials which are desirably
employed in accordance with this invention include Group 2a, 3a, 4a or
31 4b metal oxides such as silica, alumina, and silica-alumina and
32 mixtures thereof. Other inorganic oxides that may be employed either
33 alone or in combination with the silica, alumina or silica-alumina are
7~
-- 6 --
magnesia, titania, zirconia, and the like. Other suitable support
2 materials, however, can be employed, for example, finely divided
3 polyolefins such as finely divided polyethylene.
4 The metal oxides generally contain acidic surface hydroxyl
groups which will react with the metallocene added to the reaction
6 slurry. Prior to use, the inorganic oxide support is dehydrated,
7 i. e., subjected to a thermal treatment in order to remove water and
8 reduce the concentration of the surface hydroxyl groups. The treat-
g ment is carried out in vacuum or while purging with a dry inert gas
such as nitrogen at a temperature of about lOOC to about lO00C, and
11 preferably, from about 300C to about 800C. Pressure considerations
12 are not critical. The duration of the thermal treatment can be from
13 about l to about 24 hours. However, shorter or longer times can be
14 employed provided equilibrium is established with the surface hydroxyl
groups.
16 Chemical dehydration ac an alternative method of dehydration
17 of the metal oxide support material can advantageously be employed.
18 Chemical dehydration converts all water and hydroxyl groups on the
l9 oxide surface to inert species. Useful chemical agents are for
example; SiCl4; chlorosilanes, such as trimethylchlorosilane,
21 dime~hyaminotrimethylsilane and the like. The chemical dehydration is
22 accomplished by slurrying the inorganic particulate material, such as,
23 for example, silica in an inert low boiling hydrocarbon, such as, for
24 example, hexane. During the chemical dehydration reaction, the silica
should be maintained in a moisture and oxygen-free atmosphere. To the
26 silica slurry is then added a low boiling inert hydrocarbon solution
27 of the chemical dehydrating agent, such as, for example, dichlorodi-
28 methylsilane. The solution is added slowly to the slurry. The
29 temperature ranges during chemical dehydration reaction can be from
about 25C to about 120C, however, higher and lower temperatures can
31 be employed. Preferably, the temperature will be about 50C to about
32 70C. The chernical dehydration procedure should be allowed to proceed
33 until all the moisture is removed from the particulate support
34 material, as indicated by cessation of gas evolution. Normally, the
chemical dehydration reaction will be allowed to proceed from about 30
36 minutes to about l6 hours, preferably l to 5 hours. Upon completion
37 of the chemical dehydration, the solid particulate material is
38 filtered under a nitrogen atmosphere and washed one or more times
~X~8~753
7 -
1 with a dry, oxygen-free inert hydrocarbon solvent. The wash solvents,
2 as well as the diluents employed to form the slurry and the solution
3 of chemical dehydrating agent, can be any suitable inert hydrocarbon.
4 Illustrative of such hydrocarbons are heptane, hexane, toluene,
isopentane and the like.
6 The normally hydrocarbon soluble metallocene is converted to
7 a heterogeneous supported catalyst by simply depositing said at least
8 one metallocene on the support material.
9 The treatment of the support material, as mentioned above, is
conducted in an inert solvent. The same inert solvent or a different
11 inert solvent is also emp10yed to dissolve the metallocenes.
12 Preferred solvents include mineral oils and the various hydrocarbons
13 which are liquid at reaction temperatures and in which the metal-
14 locenes are soluble. Illustrative examples of useful solvents include
the alkanes such as pentane, iso-pentane, hexane, heptane, octane and
16 nonane; cycloalkanes such as cyclopentane and cyclohexane; and
17 aromatics such as benzene, toluene, ethylbenzene and diethy1benzene.
18 Preferably the support material is slurried in toluene and the
19 metallocenes and alumoxane are dissolved in toluene prior to addition
to the support material. The amount of solvent to be employed is not
21 critical. Nevertheless, the amount should be employed so as to
22 provide adequate heat transfer away from the catalyst components
23 during reaction and to permit good mixing.
24 The supported (multi) metallocene catalyst component of this
invention is prepared by simply adding the at least one metallocene in
26 the suitable solvent, preferably toluene to the support material
27 slurry, preferably silica slurried in toluene. The ingredients can be
28 added to the reaction vessel rapidly or slowly. The temperature
29 maintained during the contact of the reactants can vary widely, such
as, for example, from 0 to lO0C. Greater or lesser temperatures can
31 also be employed. Preferably, the at least one metallocene is added
32 to the silica at room temperature. When two or more metallocenes are
33 added, the addition can be sequentially or simultaneously. The
34 reaction between the at least one metallocene and the support material
is rapid, however, it is desirable that the at least one metallocene
36 be contacted with the support material for about one hour up to
37 eighteen hours or greater. Preferably, the reaction is maintained for
38 about one hour. The reaction of the at least one metallocene with the
~ 7 ~ 3
1 support material is evidenced by elemental analysis of the support
2 material for the transition metal contained in the metallocene(s).
3 At all times, the individual ingredients as well as the
4 recovered catalyst component are protected from oxygen and moisture.
Therefore, the reactions must be performed in an oxygen and moisture
6 free atmosphere and recovered in an oxygen and moisture free
7 atmosphere. Preferably, therefore, the reactions are performed in the
8 presence of an inert dry gas such as, for example, nitrogen. The
9 recovered solid catalyst is maintained in a nitrogen atmosphere.
Upon completion of the reaction of the at least one metal-
11 locene with the support, the solid metallocene containing material can
12 be recovered by any well-known technique. For example, the solid
13 metallocene containing material can be recovered from the liquid by
14 vacuum evaporation, filtration or decantation. The solid is there-
after dried under a stream of pure dry nitrogen or dried under
16 vacuum.
17 The total amount of metallocene usefully employed in
18 preparation of the solid supported catalyst component can vary over a
19 wide range. The concentration of the metallocene deposited on the
essentially dry support can be in the range of about O.OOl to about 5
21 mmoles/g of support, however, greater or lesser amounts can be
22 usefully employed. Preferably, the metallocene concentration is in
23 the range of O.OlO to 2 mmoles/g of support and especially 0.03 to
24 l mmoles/g of support.
For the production of polymer product having a narrow
26 molecular weight distribution it is preferable to deposit only one
27 metallocene onto the porous support material and employ said support
28 metallocene together with the alumoxane as the polymerization
29 catalyst.
It is highly desirable to have for many applications, such as
31 extrusion and molding processes, polyethylenes which have a broad
32 molecular weight distribution of the unimodal and/or the multi-modal
33 type. Such polyethylenes evidence excellent processability, i.e.,
34 they can be processed at a faster throughput rate with lower energy
re4uirements and at the same time such polymers would evidence reduced
36 melt flow perturbations. Such polyethylenes can be obtained by
37 providing a catalyst component comprising at least two different
~87~3
1 metallocenes, each having different propagation ~nd termination rate
2 constants for ethylene polymerizations. Such rate constants are
3 readily determined by one of ordinary skill in the art.
4 The molar ratio of the metallocenes, such as for example, of
5 a zirconocene to a titanocene~ can vary over d wide range and in
6 accordance with this invention the only limitation on the molar ratios
7 is the breadth of the MW distribution or the degree of bimodality
8 desired in the product polymer. Desirably, the metallocene to
9 metallocene molar ratio will be about 1:100 to about 100:1, and
10 preferably 1:10 to about 10:1.
11 The present invention also provides a process for producing
12 (co)polyolefin reactor blends comprising polyethylene and
13 copolyethylene-alpha-olefins. The reactor blends are obtained
14 directly during a single polymerization process, i.e., the blends of
15 this invention are obtained in a single reactor by simultaneously
16 polymerizing ethylene and copolymerizing ethylene with an alp-h~-olefin
17 thereby eliminating expensive blending operations. The process of
18 producing reactor blends in accordance with this invention can be
G 19 employed in çonjunction with other prior art blending techniques, for
20 example the reactor blends produced in a first reactor can be
21 subjected to further blending in a second stage by use of the series
22 reactorS~
23 In order to produce reactor blends the supported metallocene
24 catalyst component comprises at least two different metallocenes each
25 having different reactivity ratios.
26 The reactivity ratios of the metallocenes in general are-
27 obt-ained by methods well known such as, for example, as described in
28 "Linear Method for Dete)mining lfionomer Reactivity Ratios in
29 Copolymerization", M. Fineman and S. D. Ross, J. Polymer Science 5,
30 259 (1950) or "Copolymerization", F. R. Mayo and C. Walling, Chem.
31 Rev. 46, 191 (1950)-
32 For examp1e, to determine reactivity ratios the most widely used
33 copolymerization model is based on the following equations:
:
~ .
~:
753
-- 10 --
1 Ml* + Ml kll ~ Ml* (l)
2 Ml* + M2 kl2 ~ M2* (2)
3 M2* ~ Ml k2l ~Ml* ~3)
4 M2* + M2 k22 ~M2* (4)
where Ml refers to a monomer molecule which is arbitrarily
6 designated i (where i = l, 2) and Mj* refers to a growing polymer
7 chain to which monomer i has most recently attached.
8 The kij values are the rate constants for the indicated
9 reactions. In this case, kll represents the rate at which an
ethylene unit inserts into a growing polymer chain in which the
11 previously inserted monomer unit was also ethylene. The reactivity
12 rates follow as: rl=kll/kl2 and r2=k22/k2l wherein kll,
13 kl2, k22 and k2l are the rate constants for ethylene (l) or
14 comonomer (2) addition to a catalyst site where the last polymerized
monomer is ethylene (klX) or comonomer(2) (k2X).
16 In Table I the ethylene-propylene reactivity rates rl and
17 r2 are listed for several metallocenes. It can be seen that with
18 increased steric interaction at the monomer coordination site rl
19 increases, i.e., the tendency for ethylene polymerization increases
over propylene polymerization.
21 It can be seen from Table I that if one desires a blend
22 comprising HDPE/ethylene-propylene copolymer one would select bis-
23 (pentamethylcyclopentadienyl)zirconium dichloride and bis(cyclopenta-
24 dienyl)titaniumdiphenyl or dimethylsilyldicyclopentadienylzirconium
dichloride in ratios of about 5:l to about l:l whereas if one desires
26 a blend comprising LLDPE/ethylene-propylene one would select bis-
27 (cyclopentadienyl)zirconium dichloride and bis(cyclopentadienyl)-
28 titanium diphenyl or dimethylsilyldicyclopentadienylzirconium
29 dichloride in ratios of about lO:l to about l:lO.
The molar ratio of the metallocenes can vary over a wide
31 range and in accordance with this invention the molar ratics are
32 controlled by the product polymer blend desired.
33 Desirably, the metallocene molar ratio on the support will be
34 about lOO:l to about l:lO0, and preferably lO:l to about l:lO. The
specific metallocenes selected and their molar ratios are dependent
37~3
-- 1 1 --
1 upon the molecular composition desired for the component polymers and
2 the overall composition desired for the blend. In general, the com-
3 ponent catalyst used in a reactor blend catalyst mixture will each
4 have r values which are different in order to produce final polymer
5 compositions which comprise blends of two or more polymers.
6 TABLE I
7 Catalyst rl r2
8 CP2Ti=CH2 Al(Me)2Cl 24 0.0085
9 Cp2TiPh2 l9.5+l.5 0.0l5+.002
Me2SiCp2ZrCl2 24+2 0.029+.007
11 Cp~ZrCl2 48~2 0.015+.003
12 (MeCp)2ZrCl2 60
13 (Me5Cp)2ZrCl2 250+30 .002+0.00l
14 [Cp2ZrCl]20 50 0.007
The alumoxane which is used as the co-catalyst can be
16 employed in an amount in the range of l to lO0 moles of aluminum per
17 mole of transition metal on the support and preferably 2 to 50.
18 The present invention employs at least one metallocene compound in
19 the formation of the supported catalyst. Metallocene, i.e. a
cyclopentadienylide, is a metal derivative of a cyclopentadiene. The
21 metallocenes usefully employed in accordance with this invention
22 contain at least one cyclopentadiene ring. The metal is selected from
23 Group 4b, 5b or 6b metals, preferably 4b and 5b metals, preferably
24 titanium, zirconium, hafnium, and vanadium, and especially titanium
and zirconium. The cyclopentadienyl ring can be unsubstituted or
26 contain substituents such as, for example, hydrocarbyl substituents.
27 The metallocene can contain one, two, or three cyclopentadienyl ring
28 however two rings are preferred.
29 The metallocenes can be represented by the general formulas:
I- (Cp)mMRnXq
31 wherein Cp i~ a cyclopentadienyl ring, M is a Group 4b, 5b, or 6b
32 transition metal, R is a hydrocarbyl group having from l to 20 carbon
33 atoms, X is a halogen atom, m = 1-3, n = 0-3, q = 0-3 and the sum of
34 m+n+q is equal to the oxidation state of M.
II. (C5R'k)gRI's(C5R k)MQ3_9 and
36 III. R"s(C5R'k)2MQ'
87~3
- l2 -
1 wherein (C5R'k) is a cyclopentadienyl or substituted
2 cyclopentadienyl, each R' is the same or different and is hydrogen or
3 a hydrocarbyl radical such as alkylS alkenyl, aryl, alkylaryl, or
4 arylalkyl radical containing from l to 20 carbon atoms or two carbon
5 atoms are joined together to form a C4-C6 ring, R" is a Cl-C4
6 alkylene radical, a dialkyl germanium or silicon, or a alkyl phosphine
7 or amine radical bridging two tC5R'k) rings, Q is a hydrocarbyl
8 radical such as aryl, alkyl, alkenyl, alkylaryl, or aryl alkyl radical
9 having from l-20 carbon atoms, hydrocarboxy radical having from l-20
10 carbon atoms or halogen and can be the same or different from each
11 other, Q' is an alkylidiene radical having from l to about 20 carbon t
12 atoms, s is 0 or l, 9 is 0,l or 2, s is 0 when 9 is 0, k is 4 when s
13 is l, and k is 5 when s is 0, and M is as defined above.
14 Exemplary hydrocarbyl radicals are methyl, ethyl, propyl,
15 butyl, amyl, isoamylj hexyl, isobutyl, heptyl, octyl, nonyl, decyl,
16 cetyl, 2-ethylhexyl, phenyl and the like.
17 Exemplary halogen atoms include chlorine, bromine, fluorine
18 and iodine and of these halogen atoms, chlorine is preferred.
19 Exemplary hydrocarboxy radicals are methoxy ethoxy, butoxy,
20 amyloxy and the like.
21 Exemplary of the alkylidiene radicals is methylidene,
22 ethylidene and propylidene.
23 Illustrative, but non-limiting examples of the metallocenes
24 represented by formula I are dialkyl metallocenes such as bis(cyclo-
25 pentadienyl)titanium dimethyl, bis(cyclopentadienyl)titanium diphenyl,
26 bis(cyclopentadienyl)zirconium dimethyl, bis(cyclopentadienyl)-
27 zirconium diphenyl, bis(cyclopentadienyl)hafnium dimethyl and
28 diphenyl, bis(cyclopentadienyl)titanium dineopentyl, bis(cyclopenta-
29 dienyl)zirconium dineopentyl, bis(cyclopentadienyl)titanium dibenzyl,
30 bis(cyclopentadienyl)zirconium dibenzyl, bis(cyclopentadienyl)vanadium
31 dimethyl; the mono alkyl metallocenes such as bis(cyclopentadienyl)-
32 titanium methyl chloride, bis(cyclopentadienyl)titanium ethyl
33 chloride, bis(cyclopentadienyl)titanium phenyl chloride, bis(cyclo-
34 pentadienyl)zirconium methyl chloride, bis(cyclopentadienyl)zirconium
35 ethyl chloride, bis(cyclopentadienyl)zirconium phenyl chloride, bis-
36 (cyclo?entadienyl)titanium methyl bromide, bis(cyclopentadienyl)-
37 titanium methyl iodide, bis(cyclopentadienyl)titanium ethyl bromide,
38 bis(cyclopentadienyl)titanium ethyl iodide, bis(cyclopentadienyl)-
. ..
753
3 -
1 titanium phenyl bromide, bis(cyclopentadienyl)titanium phenyl iodide,
2 bis(cyclopentadienyl)zirconium methyl bromide, bis(cyclopentadienyl)-
3 zirconium methyl iodide, bis(cyclopentadienyl)zirconium ethyl bromide,
4 bis(cyclopentadienyl)zirconium ethyl iodide, bis(cyclopentadienyl)-
zirconium phenyl bromide, bis(cyclopentadienyl)zirconium phenyl
6 iodide; the trialkyl metallocenes such as cyclopentadienyltitanium
7 trimethyl, cyclopentadienyl zirconium triphenyl, and cyclopentadienyl
zirconium trineopentyl, cyclopentadienylzirconium trimethyl, cyclo-
. 9 pentadienylhafnium triphenyl, cyclopentadienylhafnium trineopentyl, and cyclopentadienylhafnium trimethyl.
11 Illustrative, but non-limiting examples of II and III
12 metallocenes which can be usefully employed in accordance with this
13 invention are monocyclopentadienyls titanocenes such as, pentamethyl-
14 cyclopentadienyl titanium trichloride, pentaethylcyclopentadienyl
titanium trichloride, bis(pentamethylcyclopentadienyl) titanium
16 diphenyl, the carbene represented by the formula Cp2Ti=CH2
17 and derivatives of this reagent such as Cp~Ti=CH~ Al(CH3)3,
18 (Cp2TiCH2)2, and Cp2TiCH2CH(CH3)CH2, Cp2ti-CH2CH2CH2;
19 substituted bis(Cp)Ti(IV) compounds such as bis(indenyl)titanium
diphenyl or dichloride, bis(methylcyclopentadienyl)titanium diphenyl
21 or dihalides; dialkyl, triaikyl, tetra-alkyl and pentaalkyl
22 cyclopentadienyl titanium compounds such as bis(l,2-dimethylcyclo-
23 pentadienyl)titanium diphenyl or dichloride, bis(l,2-diethylcyclo-
~4 pentadienyl)titanium diphenyl or dichloride and other dihalide com-
plexes, silicon, phosphine, amine or carbon bridged cyclopentadiene
26 complexes, such as dimethyl silyldicyclopentadienyl titanium diphenyl
27 or dichloride, methyl phosphine dicyclopentadienyl titanium diphenyl
28 or dichloride, methylenedicyclopentadienyl titanium diphenyl or
29 dichloride and other dihalide complexes and the like.
Illustrative but non-limiting examples of the zirconocenes
31 of Formula II and III which can be usefully employed in accordance
32 with this invention are, pentamethylcyclopentadienyl zirconium tri-
33 chloride, pentaethylcyclopentadienyl zirconium trichloride, the alkyl
34 substituted cyclopentadienes, such as bis(ethylcyclopentadienyl)-
zirconium dimethyl, bis(~-phenylpropylcyclopentadienyl)zirconium
36 d-,methyl, bis(methylcyclopentadienyl)zirccnium dimethyl, bis(n-butyl-
37 cyclopentadienyl)zirconium dimethyl, bis(cyclohexylmethylcyclopenta-
38 dienyl)zirccnium dimethyl, bis(n-octyl-cyclopentadienyl)zirconium
687j3
- l4 -
1 dimethyl, and haloalkyl and dihalide complexes of the above; dialkyl,
2 trialkyl, tetra-alkyl, and pentaalkyl cyclopentadienes, such as
3 bis(pentamethylcyclopentadienyl)zirconium diphenyl, bis(pentamethyl-
4 cyclopentadienyl)zirconium dimethyl, bis(l,2-dimethylcyclopenta-
dienyl)zirconium dimethyl and mono- and dihalide complexes of the
6 above, silicon, phosphorus, and carbon bridged cyclopentadiene
7 complexes such as dimethylsilyidicyclopentadienyl zirconium dimethyl,
8 methyl halide or dihalide, and methylene dicyclopentadienyl zirconium
9 dimethyl, methyl halide, or dihalide, carbenes represented by the
formulae Cp?Zr=CH2P(C~H~)2CH3, and derivatives of these compounds
11 such as Cp2ZrCH2CH(CH3)CH2.
12 Bis(cyclopentadienyl)hafnium dichloride, bis(cyclopenta-
13 dienyl)hafnium dimethyl, bis(cyclopentadienyl)vanadium dichloride and
14 the like are illustrative of other metallocenes.
The inorganic oxide support used in the preparation of the
16 catalyst may be any particulate oxide or mixed oxide as-previously
17 described which has been thermally or chemically dehydrated such that
18 it is substantially free of adsorbed moisture.
19 The specific particle size, surface area, pore volume, and
number of surface hydroxyl groups characteristic of the inorganic
21 oxide are not critical to its utility in the practice of the
22 invention. However, since such characteristics determine the amount
23 of inorganic oxide that it is desirable to employ in preparing the
24 catalyst compositions, as well as affecting the properties of polymers
formed with the aid of the catalyst compositions, these character-
26 istics must frequently be taken into consideration in choosing an
27 inorganic oxide for use in a particular aspect of the invention. For
28 example, when the catalyst composition is to be used in a gas-phase
29 polymerization process - a type of process in which it is known that
the polymer particle size can be varied by varying the particle size
31 of the support - the inorganic oxide used in preparing the catalyst
32 composition should be one having a particle size that is suitable for
33 the production of a polymer having the desired particle size. In
34 general, optimum results are usually obtained by the use of inorganic
oxides having an average particle size in the range of about 30 to 600
36 microns, preferably about 30 to lO0 microns; a surface area of about
'~tj~ 5
- l5 -
1 50 to l,000 square meters per gram, preferably about lO0 to 400 square
2 meters per gram; and a pore volume of about 0.5 to 3.5 cc per gram;
3 preferably about 0.5 to 2cc per gram.
4 The polymerization may be conducted by a solution, slurry, or
gas-phase technique, generally at a temperature in the range of about
6 0-160C or even higher, and under atmospheric, subatmospheric, or
7 superatmospheric pressure conditions; and conventional polymerization
8 adjuvants, such as hydrogen may be employed if desired. It is
9 generally preferred to use the catalyst compositions at a concentra-
tion such as to provide about O.OOOOOl - 0.005%, most preferably about
11 O.OOOOl - 0.0003%, by weight of transition metal based on the weight
12 of monomer(s), in the polymerization of ethylene, alone or with one or
13 more higher olefins.
14 A slurry polymerization process can utilize sub- or super-
atmospheric pressures and temperatures in the range of 40-110C. In a
16 slurry polymerization, a suspension of solid, particulate polymer is
17 formed in a liquid polymerization medium to which ethylene, alpha-
18 olefin comonomer, hydrogen and catalyst are added. The liquid
19 employed as the polymerization medium can be an alkane or cycloalkane,
such as butane, pentane, hexane, or cyclohexane, or an aromatic hydro-
21 carbon, such as toluene, ethylbenzene or xylene. The medium employed
22 should be liquid under the conditions of the polymerization and rela-
23 tively inert. Preferably, hexane or toluene is employed.
24 A gas-phase polymerization process utilizes superatmospheric
pressure and temperatures in the range of about 50-l20C. Gas-phase
26 polymerization can be performed in a stirred or fluidized bed of
27 catalyst and product particles in a pressure vessel adapted to permit
28 the separation of product particles from unreacted gases. Thermo-
29 stated ethylene, comonomer, hydrogen and an inert diluent gas such as
nitrogen can be introduced or recirculated so as to maintain the
31 particles at a temperature of 50-120C. Triethylaluminum may be
32 added as needed as a scavenger of water, oxygen, and other adventi-
33 tious impurities. Polymer product can be withdrawn continuously or
34 semi-continuously at a rate such as to maintain a constant product
inventory in the reactor. After polymerization and deactivation of
36 the catalyst, the prcduct polymer can be recovered by any suitable
37 means. In commercial practice, the polymer product can be recovered
38 directly from the gas phase reactor, freed of residual monomer with a
i8 753
-- 16 --
1 nitrogen purge, and used without further deactivation or catalyst
2 removal. The polymer obtained can be extruded into water and cut into
3 pellets or other suitable comminuted shapes. Pigments, anti-oxidants
4 and other additives, as is known in the art, may be added to the
polymer.
6 The molecular weight of polymer product obtained in accor-
7 dance with this invention can vary over a wide range, such as low as
8 500 up to 2,000,000 or higher and preferably l,000 to about 500,000.
9 Since, in accordance with this invention~ one can produce
high viscosity polymer product at a relatively high temperature,
11 temperature does not constitute a limiting parameter as with the prior
12 art homogeneous metallocene/alumoxane catalysts. The catalyst systems
13 described herein, therefore, are suitable for the polymerization of
14 olefins in solution~ slurry or gas phase polymerizations and over a
lS wide range of temperatures and pressures. For example, such
16 temperatures may be in the range of about -60C to about 280C and
17 especially in the range of about 0C to about 160C. The pressures
18 employed in the process of the present invention are those well known,
19 for example, in the range of about l to 500 atmospheres, however,
higher pressures can be employed.
21 The polydispersites (molecular weight distribution) expressed
22 as Mw/Mn are typically from l.5 to 4.0 or greater. The polymers can
23 contain up to l.0 chain end insaturation per molecule.
24 The polymers produced by the process of this present
invention are capable of being fabricated into a wide variety of
26 articles, as is known for homopolymers of ethylene and copolymers of
27 ethylene and higher alpha-olefins.
28 In a slurry phase polymerization, tile alumoxane co-catalyst,
29 preferably methyl alumoxane, is dissolved in a suitable solvent,
typically in an inert hydrocarbon solvent such as toluene, xylene, and
31 the like in a molar concentration of about 5x10-3M. However,
32 greater or lesser amounts can be used.
33 The present invention is illustrated by the following
34 examples.
Examples
36 In the Examples following, the alumoxane employed was
37 prepared by adding 45.5 grams of ferrous sulfate heptahydrate in 4
38 equally spaced increments over a 2 hour period to a rapidly stirred 2
~875;~
7 --
1 liter round-bottom flask containing l liter of a lO.0 wt. percent
2 solution of trimethylaluminum (TMA) in hexane. The flask was
3 maintained at 50C and under a nitrogen atmosphere. Methane produce
4 was continuously vented. Upon completion of the addition of ferrous
sulfate heptahydrate, the flask was continuously stirred and
6 maintained at a temperature of 50 for 6 hours. The reaction mixture
7 was cooled to room temperature and allowed to settle. The clear
8 solution was separated from the solids by decantation. The aluminum
9 containing catalyst prepared in accordance with this procedure
contains 35 mole percent of aluminum present as methylalumoxane and 65
11 mole percent of aluminum present as trimethylaluminum.
12 Molecular weights were determined on a Water's Associates
13 Model No. l50C GPC (Gel Permeation Chromatography). The measurements
14 were obtained by dissolving polymer samples in hot trichlorobenzene
and filtered. The GPC runs are performed at l45C in trichlorobenzene
i6 at l.0 ml/min flow using styragel columns from Perkin Elmer, Inc. 300
17 microliters of a 3.l% solution in trichlorobenzene were injected and
18 the samples were run in duplicate. The integration parameters were
19 obtained with a Hewlett-Packard Data Module.
~ Melt index data for the polyethylene products were determined
21 at l90C according to ASTM Method Dl238.
22 Cataly5t Preparation
23 Catalyst A
24 lO grams of a high surface area (Davison 952) silica,
dehydrated in a flow of dry nitrogen at 600C for 5 hours was slurried
26 with 50 cc of dry toluene at 30C under nitrogen in a 250 cc
27 round-botto~ flask using a magnetic stirrer. O.lO0 grams
28 bis(cyclopentadienyl) zirconium dichloride dissolved in 25 cc of
29 toluene was added dropwise to the silica slurry over l5 minutes with
constant stirring. The suspension was stirred for 2 hours at 30C and
31 allowed to settle. The excess toluene was decanted. The recovered
32 solids were washed with three lO cc portions of toluene and dried in
33 vacuum for 4 hours. Analysis of the supported catalyst indicated that
34 it contained 0.3l wt. percent zirconium.
Catalyst B
36 Catalyst B was prepared identically as in Catalyst A with the
37 exception that 250 mg of bis(cyclopentadienyl) titanium diphenyl was
38 substituted for the zirconocene of Catalyst A. Analysis of the
~'~68753
8 -
1 supported catalyst indicated that it contained 0.48 wt. percent
2 titanium.
3 Catalyst C
4 Catalyst C was prepared identically as in Catalyst A with the
exception that 100 mg of bis(pentamethylcyclopentadienyl) zirconium
6 dichloride was substituted for the zirconocene of Catalyst A.
7 Analysis of the supported catalyst indicated that it contained 0.21
8 wt. % zirconium.
9 Catalyst D
Catalyst D was prepared identically as in Catalyst A with the
11 exception that 10.0 grams of gamma alumina was substituted for the
12 silica and 0.100 grams of bis(cyclopentadienyl) zirconium dichloride
13 was employed. The high surface area gamma aluminum (Strem Co.) had
14 been dehydrated in a flow of dry nitrogen at 600C for 5 hours prior
to use. Analysis of-the supported catalyst indicated that it
16 contained 0.31 wt % zirconium.
17 CatalYst E
18 Catalyst E was prepared as in Catalyst A with the exception
19 that 100 mg of bis(methylcyclopentadienyl)zirconium dichloride was
substituted for the zirconocene of Catalyst A. Analysis of the
21 supported catalyst indicated that it contained 0.29 weight percent
22 zirconium.
23 Polymerizations
24 Example 1
A l-liter stainless steel pressure vessel, equipped with an
26 incline blade stirrer, an external water jacket for temperature
27 control, a septum inlet and vent line, and a regulated supply of dry
28 ethylene and nitrogen, was dried and deoxygenated with a nitrogen
29 flow. 500 cc of dry, degassed toluene was introduced directly into
the pressure vessel. 10.0 cc of 0.850 molar (in total aluminum)
31 alumoxane in toluene was injected into the vessel by a gas-tight
32 syringe through the septum inlet and the mixture was stirred at 1,200
33 rpms and 85C for 5 minutes at 0 psig of nitrogen. 25 mg of Catalyst A
34 was injected into the vessel with a nitrogen flow. After 1 minute,
hydrogen at 40 psig and ethylene at 200 psig was admitted while the
36 reaction vessel was maintained at 85C. The ethylene was passed into
37 the vessel for 5 minutes at 200 psig at which time the reaction was
38 stopped by rapidly venting and cooling. 10.6 grams of powdery white
1;26~3753
,9
1 polyethylene was recovered having a melt index of 0.35 grams/lO min.
2 Specific polyrnerization activity is defined as the weight of polymer
3 produced by a given weight of transition metal contained in a catalyst
4 per hour and per atmosphere of absolute monomer pressure. i.e.,
5Specific activity = g polymer
6 gZr x hr x atmospheres of monomer
7For Example l,
8Specific activity = 10.6 9
9 7.8 x lO 5gZr x 0.083 hr x lO.9
10 = 150,200 g/gZr. hr. atm.
11 Example 2
12 A l-liter stainless steel pressure vessel, equipped with an
13 incline blade stirrer, an external water jacket for temperature
14 control, a septum inlet and vent line, and a regulated supply of dry
ethylene and nitrogen, was dried and deoxygenated with a nitrogen
16 flow. 500 cc of dry, degassed toluene was introduced directly into
17 the pressure vessel. lO.0 cc of alumoxane (.850 mmoles in total ,
18 àluminum) was injected into the vessel by a gas-tight syringe through
19 the septum inlet and the mixture was stirred at l,200 rpms and 85C
for 5 minutes at 0 psig of nitrogen. 25 mg of Catalyst A was injected
21 into the reactor with a nitrogen stream. After l minute~ lO0
22 milliliters of l-butene was added and the vessel was pressured to l35 1,
23 psig with ethylene. Ethylene flow was maintained for 6 minutes while
24 maintaining the reaction vessel at 85C. The results of the
polymerization are summarized in Table I.
26 Example 3
27 The polymerization was performed identically as in Example l
28 with the exception that 25 milligrams of Catalyst B were substituted
29 for Catalyst A. The results of the polymerization are summarized in
Table I.
31 Example 4
32 The polymerization was performed identically as in Example 2
33 with the exception that 40 milligrams of Catalyst B were substituted
34 for Catalyst A. The results of the polymerization are summarized in
Table I.
8753
- 20 -
1 Examples 5 and 6
2 The polymerizations for Examples 5 and 6 were performed
3 identically as in Example l and 2 respectively with the exception that
4 lO0 milligrams of Catalyst C were substituted for Catalyst A. The
results of the polymerizations are summarized in Table I.
6 Examples 7 and 8
7 The polymerizations for Examples 7 and 8 were performed
8 identically as in Example 1 and 2 respectively with the exception that
9 the polymerization temperature was maintained at lO0C. The results
of the polymerizations are summarized in Table I.
11 Examples 9 and lO
, .
12 The polymerizations for Examples 9 and lO were performed
13 identically as in Example l and 2 respectively with the exception that
14 Catalyst D was substituted for Catalyst A. The results of the
polymerizations are summarized in Table I.
16 Example ll
17 The polymerization was performed identically as in Example l
18 with the exception that lO mg of Catalyst E was substituted for
19 Catalyst A. The results of the polymerization is summarized in Table
l.
21 ExamPle l2
22 The polymerization was performed identically as in Example 4
23 with the exception that 2.14 mg of pure, unsupported bis(cyclopenta-
24 dienyl)titanium diphenyl dissolved in lO cc toluene was substituted
for the supported Catalyst B. The results are summarized in Table l.
26 Example l3
27 Catalyst Preparation
28 lO grams of a high surface area (Davison 952) silica,
29 dehydrated in a flow of dry nitrogen at 800C for 5 hours was slurried
with 50 cc of dry toluene under a nitrogen flow at 50C in a 250 cc
31 rouhd-bottom flask using a magnetic stirrer. O.lO0 grams each of
32 bis(cyclopentadienyl) titanium diphenyl and bis(pentamethyl-
33 cyclopentadienyl) zirconium dichloride dissolved together in 25 cc of
34 toluene were added to the silica slurry dropwise over lS minutes under
constant stirring. The suspension was stirred at 50C for 2 hours,
36 upon settling the excess toluene was decanted. The metallocene
37 treated silica was washed by stirring and decantation with three lO cc
l~tj87~
~ - 2l -
1 portions of toluene and dried in vacuum for 4 hours. Analysis of the
2 supported catalyst indicated that it contained 0.23 weight percent
3 zirconium and 0.l4 weight percent titanium on silica.
4 Polymerization
A l-liter stainless steel pressure vessel, equipped with an
6 incline blade stirrer, an external water jacket for temperature
7 control, a septum inlet and vent line, and a regulated supply of dry
8 ethylene in nitrogen, was dried and deoxygenated with a nitrogen
9 flow. 500 cc of dry, degassed toluene was introduced directly into
the pressure vessel. lO cc of alumoxane solution (0.9l molar in total
11 aluminum) was injected into the vessel by a gas-tight syringe through
12 the septum inlet and the mixture was stirred at 1,200 rpms at lO0 for
13 5 minutes at 0 psig nitrogen. 20 mg of the silica supported
14 metallocene catalyst was injected into the vessel under a nitrogen
flow. After l minute, hydrogen at 40 psig and ethylene at 200 psig
16 were admitted into the reaction vessel which was maintained at lO0C.
17 Ethylene was passed into the vessel for 3 minutes in order to maintain
18 the pressure. The reaction was stopped by rapidly venting and cooling
19 the reactor. 7.5 grams of powdery white polyethylene were recovered
having a weight average molecular weight of 59,400, a number average
21 molecular weight of 3,300, a molecular weight distribution of l8.l.
22 The GPC showed a bimodal molecular weight distribution. The product
23 had a melt index of 25 grams/lO minutes and a density of 0.960 g/cc.
24 The specific activity was 280,000 g/g metal hr. atm..
ExamPle l4
26 Polymerization
27 A l-liter stainless steel pressure vessel, equipped with an
28 incline blade stirrer, an external water jacket for temperature
29 control, a septum inlet and vent line, and a regulated supply of dry
ethylene in nitrogen, was dried and deoxygenated with a nitrogen
31 flow. 400 cc of dry, degassed toluene was introduced directly into
32 the pressure vessel. lO cc of alumoxane solution (0.9l molar in total
33 aluminum) was injected into the vessel by a gas-tight syringe through
34 the septum inlet and the mixture was stirred at 1,200 rpms at 92 for
5 minutes at 0 psig nitrogen. lO mg of the catalyst as prepared in
36 Example l3 were injected into the vessel under a nitrogen flow. After
37 l minute, hydrogen at 80 psig and ethylene at 400 psig were admitted
38 into the reaction vessel which was maintained at lO0C. Ethylene was
3753
- 22 -
1 passed into the vessel for 16 minutes while maintaining the reaction
2 vessel at 92C. The reaction was stopped by rapidly venting and
3 cooling the reactor. 12.8 grams of powdery white polyethylene were
4 recovered having a weight average molecular weight of 196,500, a
S number average molecular weight of 8,800, a molecular weight
6 distribution of 22.3. The GPC showed a bimodal molecular weight
7 distribution. The product had 'd melt index of 0.09 grams/10 minutes
8 and a density of 0.967 g/cc. The specific activity was 130,000 9/9
9 metal. hr. atm..
Example 15
11 Gas-Phase Polymerization
12 A 1-liter stain7ess stee7 pressure vessel, equipped with a
13 paddle-blade stirrer, an external water jacket for temperatùre
14 control, a septum inlet and vent line, and a regulated supply of dry
ethylene in nitrogen, was dried and deoxygenated with a nitrogen flow.
16 40 grams palystyrene granules (10 mesh) were introduced into
17 the pressure vessel. S.0 cc of alumoxane (9 mmoles in total aluminum)
18 were injected into the vessel by a gas-tight syringe through the
19 septum inlet and the mixture was stirred at 1,200 rpms at 85C for 5
minutes at 0 psig of nitrogen. 100 milligrams of the prepared solid
21 catalyst described in Example 13 was injected into the vessel with
22 nitrogen flow. After 1 minute, ethylene at 150 psig was admitted for
23 40 minutes while maintaining the reaction vessel at 85C. The
24 reaction was stopped by rapid venting and cooling. 4.5 grams of
powdery white polyethylene was recovered having a weight average
26 molecular weigl-t of 39,500, a number average molecular weight of
27 3,600, a molecular weight distribution of 11Ø The GPC showeda
28 bimodal molecular weight distribution. The polyethylene had a melt
29 index of 50 grams/10 minutes and a density of 0.960 grams per cc. The
specific activity was 4,200 9/9 metal. hr. atm.
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