CA2135401A1

CA2135401A1 - Olefin polymerization catalyst system

Info

Publication number: CA2135401A1
Application number: CA002135401A
Authority: CA
Inventors: Charles K. Buehler
Original assignee: Individual
Current assignee: Millennium Petrochemicals Inc
Priority date: 1992-05-11
Filing date: 1993-05-11
Publication date: 1993-11-25
Also published as: NO944286D0; BR9306341A; FI945294A0; JPH07508062A; WO1993023162A1; NO944286L; RU94046060A; CN1082058A; ZA933286B; KR950701550A; FI945294A; EP0640012A4; AU4241193A; EP0640012A1

Abstract

The present invention is directed to a cocatalyst comprising an aluminum trialkyl and an alkoxysilane for use in preparing a catalyst system for the polymerization of olefins containing a titanium III component and an electron donor having an ultraviolet absorption wavelength of less than 250 nanometers.

Description

2 1 3 ~ O 1 PCr/US93/04385 OLEFIN POLYME:RIZATION CATALYST SYSTEM
.
The present invention is directed to an ole~-in polymerization catalyst system based upon a member of the class of conventional titanium trichloride catalysts, in association with a novel cocatalyst based upon an aluminum trialkyl and a silane component as further des~ribed herein. The cocatalyst provides isotactic ole~in polymers with higher catalytic activity than catalyst systems of the prior art.
One of the earliest classes o~ Ziegler-Natta catalyst systems developed for use in the polymerization of olef~ins, especially alpha-olefins such as ethylene and propylene, were catalyst systems that include titanium and aluminum in the form of titanium trihalide catalysts and orga~oaluminum compounds as cocatalysts.
The relatively simple nature of these systems provided a compelling case for their use compared to more complex so-called 'high activity' Ziegler-Natta solid catalyst components which include titani~m ~IV) and magnesium.
The polymerization of propylene among other stereochemical monomers concerns itself with the structural ordering of the resulting polymer. The most desirable polymers for industrial use are isotactic, those where i~ recurring triads,:the depending methyl groups are-o~ the same side of the molecule, affording long term order and hence properties related to developed~crystallinity.
Naturally, it was and is important -- --commercially to secure such highly isotactic polymers in high yield, and therefore one sought catalysts of high activity as measured by weight of polymer per unit weight of catalyst, and to control other polymerization~ -parameters to direct morphology of the resulting polym~

, . . .

W093/23162 2 1 3 5 4 0 1 PCT/USg~/04385 to afford other~desirable properties such as high crystalline melting point, and high bulk density.
Unfortuna~ely, the use of aluminum trialkyl cocatalysts with titanium trichloride catalysts never provided commercially useful polymers. It was discovered, however, that dialkyl aluminum halides were effective and these cocatalysts have been used nearly exclusively in industry. No satisfactory substitute had heretofore been found despite considerable interest and economic motiva~ion. It became generally recogniæed in the art that while aluminum alkyls such as triethyl aluminum could usefully be employed as cocatalysts for titanium (IV) catalysts they were unuseable on a commercial scale for titanium (III) polymerizations.
It was, therefore, highly surprising t~ `
discover that an aluminum alkyl used coordinately with a silane modifier as described was not only e~fective in a titanium (III3 polymerization to provide polymer in high yield, but would produce stereoregular polypropylene of high isotacticity and other desirable properties such as high crystalline meltin~ point and high bulk density.
This convenient, homogeneous catalyst system, commercially effective in slurry ~olymeriæations, also finds similar adv ntage in the gas phas~ polymerization of propylene.. Thus, in optimized systems, polypropylene of greater than 95 to 97% heptane inso~u~les can be sustainably produced at an activity in excess of 6000- ¦
~000 lb/lb catalyst with a crystalline melting point of ~t least 160 to 16S~ and bul~ densities in excess of 24.
As noted above, such cocatalyst systems have been used heretofore in connection-w-it~~-titanium (IV) WO93/23162 2 1 ~ 5 4 0 1 PCT/~S93/04385 catalysts. And where polymers for ilm-making were to be prepared other researchers have utilized such systems as, for example, co~round TiCl3.AA and phosphine oxide with added alkoxysilane in conjunction with an aluminum alkyl, with some success, although thé resulting polymer is of lower crystallinity so to reduce haze in the film.
The phosphine oxide is contraindicated in any event insofar as its donative potential is somewhat too great for successful mediation of the cataly~ic process, and it is less acceptable in the sense of ecological concerns.
The more typical disc~osures involving the use of si-anes as cocatalyst components for titanium ~III) polymerization, with or without an internal election donor, uniformly utilize as cocatalyst the conventional diethyl aluminum chloride.
In experimenting with systems employing a ti~anium (I~I) catalyst component including an ~internal) electron donor, it has also been found by the present inventor that the characteristics, particularly the donative potential of shareable electrons provîded by~the electron donor can p~ay a key role in providing polymers of ~esirable characteri~stics for commercial applications. ~
~ ~ In genera~, the selected elec~ron donor will exhibit an ultraviolet absorption wavelength of less ~ ~ - - -than about 250 nanometers, re}lective of the strength of : ~~ -~
electron bonding and hence the relative ease of donative coordination. The lower wavelengths are associated with more strongly bound electron pairs and thus evidence --more moderate donative potential.

_ 213~
W~93/23162 PCT/US93/04385 While not wishing t~ be bound by an essentially hypothetical elucidation of the invention, it is believed that the coordinate use of a selected internal donor, and the trialkyl aluminumlalkoxysilane cocatalysts, moderates and modulates the oxidation reduction reaction in polymerization so as to maintain and stabilize in a relative steady state the active form of the Til 3 catalyst, preventing o~erreduction of the active species while directing and ordering the production of the desired isotactic product in the case of propylene. In the case o~ use of the donor at the preparative stage for the titanium component, the internal donor is believed as well to assist in the forming of the desired ~ or ~ crystalline form of the TiCl 3 component.
In accordance with the present invention a catalyst system is provided which comprises, as a catalyst, a titanium (III) containing component, such as TiX3.rMXlm, where X and Xl are the same or different and are halogen; M is a metal of Group III of the Periodic Table of the Elements; m is an integer of 3; and r is 0 to 0.7.
The titanium.~III) component is associated .
with a selected electron donor of moderate donative potential, preferably an ether or an ester. Pre~erably, in the titanium (III) catalyst om~onent-X and Xl are chlorine; and M is aluminum. More preferably, r is ~ to 0.33.
The cocatalyst component comprises a trialkyl aluminum compound modified with-a- silane compound having the structural formula (oRl)4~ SiR2DR3q, where Rl is hydrocarbyl; and R2 and R3 are~-th~-same or different and 'I

W O 93/23162 2 1 3 5 1 ~ 1 P ~ ~US93/04385 ~re hydrocarbyl; p is 0 or an int~-er o~ 1 or 2; and q is an integer of 1 to 3, with the proviso that the sum o~ p and q does not exceed 3.
Preferably, the trialkylaluminum compound which functions as a cocatalyst has the structural formula AlR3 where R is C1 to C6 alkyl. More.preferably, in this componen~ R is Cl to C4 a-lkyl- Most preferably, this component is triethy1aluminum.
The TiC13 or TiCl3.AA co~ponent is associated with an electron donor, preferably an organic ether or ester. This ~itanium (III) component may comprise as prepared the electron donor, as described, for example in U.S. Patent Nos. 4,060,593 or 4,115,533 incorporated herein by reference. Thus, titanium tetrachloride may be reduced in situ, for example, with an aIuminum alkyl, reacted with an electron donor and activated with titanium tetrachloride to form the active TiCl3 component, pre~erably in the ~ or ~ form.
-In this embodiment, the preferred electron donor is an organic ether such as a di-alkyl ether, preferably C6 - C 2 alkyl, and most preferably di-isoamyl ether,; di-n-octyl ether or di-n-dodecyl ether.
Obviously, other readily associable electron donors may b~ utilized-to equivalent effect~ The electron donor is employe~-~n an amount of 0.1 to 0.4 mm/mol TiC13, preferably 0.2 to 0.3 mm/mol TiCl3.
Alternatively, the source of titanium (III) may~be free of an electron donor, for example, it may be a-coground TiCl3/AlCl3 as is known and available in the art~.l In su~h case, the titanium (III) containing 213~01 component is associated with an electron donor prior to use. In this embodiment, the preferred electron donor is an organic ester such as a compound having the structural formula R4 ~

where R4 is hydrogen, Cl to C4 alkyl or Cl to C4 alkoxy;
Rs is C to C 4 alkyl; and n is 0 or an integer of l to 3. ~his electron donor component, more preferably, is a compound where R4 is hydrogen; R5 is C2 to C4 alkyl; and n is l. Most preferably, this component is ~utyl benzoate.
In this embodiment the molar ratio of the titanium component to ester is in the range of between about l:l and about 20:1. More preferably, this molar ratio is in the range of between about 3:l and about 6:1.
In this embodimentl the electron donor component is preferably introduced into the catalyst system by being intimately blended together with the titanium (III3 component. Preferably, this intimate blending is provided by milling or simple mixing. More prefera~ly, this blending is accomplished by milling, especially by ballmilling.
The silane compound, useful as a cocatalyst modifier h~s the structural formula (OR~ p_~SiR2 R3 where Rl is hydrocarbyl; R2 and R3 are the same or different and are hydrocarbyl; p is 0 or an integer of l or 2; and ~ is an integer of l to 3, with the proviso that the sum of p and q does not exceed 3.

Prefer~bly, in this cocatalyst component Rl is alkyl;
and RZ and R3 are the same or different and are alkyl or cycloalkyl. More preferably, this component is a silane compound where Rl is C to C6 alkyl; and R2 and R3 are the same or different and are cl to c6 alkyl or cycloalkyl.
Still more preferably Rl is Cl to Ca alkyl;
and R2 and R3 are the same or different and are C -C6 alkyl or cycloalkyl. Even still more prefer~bly, p is 0 or l; and q is 1.
Typically, the silane cocatalyst modifier is one or more o~ isobutyltrimethoxysilane, isobutylisopropyldimethoxysil~ne, diisopropyldimethoxysilane, cyclohexylmethyldimethoxysilane or dicyclopentyldimethoxysilane- i Most preferably, the second catalyst component is isobutylisopropyldimethoxysilane or diisopropyldimethoxy- silane.
The components of the catalyst system are presen~ in concentrations such that the molar ratio of the titanium~ containing compound to the silane compound i-s in the range of between about 1:0.2 and about 1-1.2. Preferably, this molar ratio is in the range of between about 1:0.4 and about 1:1.1. Still more preferably,--this molar ratio is in the range of between about ~:~.S- and about l:0.9.
The molar ratio of the trialkylaluminum compound, to the silane compound, is in the range of between abaut S:l and about 20:1. Prefera~ly, this molar ratio is in the range of between abo r 7 :1 and about 15~ - Still more preferably, the molar ratio of 213S~Ol W093~23162 PCT/US93/04385 the trialkylaluminum component to the silane compound is in the range of between ~bout 8:1 and about 12:1.
The present invention is also directed to a process for polymerizing an olefin, generally in slurry or gas phase. In this process an olefin is polymerized under olefinic polymerization conditions in the presence of the catalyst system of the subject invention.
Olefinic polymerization conditions are preferably those that involve conducting the polymerization reaction at a temperature in the range of between about 20C and about 150C and at a pressure in the range of between about atmospheric and about 2,000 pounds per square inch gauge (psig).
Preferably, the process of polymerizing an olefin is directed to alpha-olefins which are polymerized in the presence of a catalyst system within the scope of the present invention under alpha-olefin polymerization conditions which include a temperature in the range of between about 40C and about 110C and a pressure in the range of between about 100 psig and about 1000 psig.
More preferably, the process of this invention is directed to the polymerization of an alpha-olefin having 2 to 8 carbon atoms under alpha-olefin polymerization conditions which include a polymerization reaction temperature in the range of between about 50C
and about 100C and a polymerization'reaction pressure of between about 200 psig and about 800 psig.
~ Still more preferably, the process of this invention involves the polymerization of an alpha-olefin having 2 to,6 carbon atoms under alpha-olefin po1ymerization condieions comprising a temperature of WO93/23162 2 1 3 5 '1 0 1 PCT/~S93/04385 _g_ between a~out 60C and about 92C and a pressure in the range of between about 300 psig and about 600 psig.
Even still more preferably, the process of the subject invention concerns the polymerization of an alpha-olefin selected from the group consisting of ethylene and propylene under alpha-olefin polymerization conditions comprising a temperature in the range between about 62C and about 80C and a pressure in the range of between about 3S0 psig and about 550 psig.
Most preferably, the process of the present invention is directed to the polymerization of propylene under propylene polymerization conditions which involve a reaction at a temperature in the range of between about 6~C and about 90C and at a pressure in the range between about 400 psig and about 500 psig.
In a preferred embodiment of the process of the present invention, the polymerization of an olefin utilizing the catalyst system of this invention, hy~rogen may optionally be provided thereto.
In the~preferred embodiment where the polymerization occurs in the liquid phase the reaction occurs in a so-called liquid pool wherein the only diluent is the olefin polymerized, prefera~ly propylene.
In the pref rred embodiment where the polymerization reaction occurs in the gas phase, the reaction occurs in a stationary-.flui~ zed ~ed or a stirred bed. The polymerization may-a-~so be conducted in cascaded reactors, i.e., reactors whether for suspension, gas phase or high pressure polymerization, are linked func~ionally or ln practice such that the polymerization product of the first reactor is ~urther reacted, usually under diff.ë~e-.nt conditions, in a second reactor to ~ ,, WO93/23162 2 1 ~ 5 ~ O 1 PCT/US93/04385 secure a compatibilited product of diverse characteristics.
In the first embodiment aforementioned in which an electron donor, preferably an ether is reacted with the catalyst in a preparative stage an aluminum alkyl or alkyl halide component is employed as a reductant; in consequence this component may have some catalyst reactivi~y before it is associated with the TEAL~silane cocatalyst component of this invention.
This can be inconvenient for catalyst feed systems utilizing polymerizablé monomer carrier such as is commonly the case in gas phase operations. Accordingly, in such instances it is typical to deactivate for example any residual aluminum chloride, which can conveniently be accomplished by reaction with butyl benzoate. The resulting coordination cocatalyst then relies solely upon the TEALlsilane system for cocatalyst function.
A particular advantage of the present cocatalyst resides in its capacity to f~nction ef ectively both with the titanium (III) catalysts and titanium (IV) catalysts, such that the respective catalysts used conjointly in a single reactor may be commonly cocatalyzed so to prepa~e polymer product of diverse characteristics, e.g., different molecular weight. These characteristics may then be controllably altered by suitable selection of catalyst ratio having regard for the individual characteristics such as activity levels, or stereoregulating capacity, etc. In consequence, the invention is understood to relate as well to catalyst systems which include, in the broadest sense, transition metal tIlI) and (IV) combinations W O 93/23162 2 ~ 3 5 ~ ~ 1 PC~r/~S93/04385 which are then conunonly cocatalyzed with the disclosed TEAL/silane components.

- I

=_=- , 1, W093/~3162 213~101 A catalyst system was prepared by combining titanium trichloride (0.04 g.),(itself prepared according to the protocol of Example 4 of U.S. Patent No. 4,115,~33) isobutylisopropyldimethoxy-silane (I~IP) and triethylaluminum (TEAL) in a concentration such that the molar ratio of these components was ~.0:0.5:4.6, respectively. This catalyst system was introduced into a reactor free of air and water.
The reactor into which the catalyst system was introduced was next charged with hydrogen gas (500 ml.) and liquid propylene (325 g., 650 ml~). The polymerization reaction was thereupon initiated by heating and pressurizing the reactor to a temperature of 70C and a pressure of 460 psiy. Concurrently wîth this heating and pressurizing step the s~irrer, with which the reactor was eguipped, was a~tivated. The stirrer rotated at 400 revolutions per minute. The polymerization reaction, operated under these conditions, was continued for 1 hour. The reaction was terminated after 1 hour by venting the excess propylene.
After the one hour propylene polymerization, the polypropylene product of the polymeri~ation reaction was weighed and analyzed. The polymer analysis constituted the determination of the coneentration therein o~ titanium, a measure of undesira~le catalyst incorporation therein, by quantitative analysis well known in the art. In addition, a determination of percent heptane insol~bility of the po~ymex, a measurement.of polypropy~ene isotacticity, was also conducted.

WO93/23162 -13- 2 ~ ~ 5 ~ ~ 1 PCT/~S93/0438~

The po~ypropylene percent heptane insolubility was determined in a procedure wherein a finely graund sample (20 mesh) of the polypropylene obtained in the above discussed polymerization reaction was heated at 100C for 30 minutes in a vacuum oven. The heated sample, disposed in a tare container, i.e., a thimble, was then carefully weighed. The ground polymer, disposed in the thimble was thereupon disposed in an extraction flask already filled with approximately 150 ml. of n-heptane. The n-heptane was heated to boiling and refluxed, with the polypropylene sample disposed therein, for 90 minutes. After 9~ minutes, reflexing ceased and the thimble containing the polypxopylene sample was removed.
The thimble containing the polypropylene sample was rinsed in acetone after which it was again -heat~d in the same vacuum oven, at 100C for 30 minutes.
The polypropylene sample, still in its tare container, was cooled to ambient temperature and again weighted.
- Percent heptane insolubility was determined as the ratio of the difference in net weight of the pol~propylene before and after contact with boiling n-hc:~tane for 90 minutes to the net polypropylene weight p~ior to such contact.
Another polymer property analyzed was melt flow rate, determined in accordance with A5TM Test Procedure ~ ~~
D-1238. Finally, the polypropylene was tested to determine its bulk density, in pounds per cubic foot, which was obtained by taring a vessel of known volume and weighing the vessel of known volume filled with the WO93/23162 2 1 3 ~ ~ O 1 PCT/US93/04385 polypropylene produced in the above-discussed polymerization.
The activity of the catalyst, in terms of polypropylene weight per unit weight of catalyst, was determined by weighing the polypropylene generated during the 1 hour polymerization run and dividing that number by the weight of catalyst charged into ~he reactor.
The results of this example are summarized in the Table which follows the last example.

, _ I

W~g3/23162 PCT/~S93/043~5 Example 1 was identically reproduced but for the composition of the cat~lyst. In Example 2 the molar ratio of titanium trichloride, to isobutylisopropyldimethoxysilane, to triethylaluminum, was 1:0.7:6Ø Again titanium trichloride, was present in an amount of 0.04 g.
The results of this example are summarized in the Table.

WO93/~3162 PCT/US93/0438 Example l was identically reprod~ced again but for the composition but for ~he relative amounts of the catalyst components of the catalyst system. In Example 3 the molar ratio of titanium trichloride to isobutylisopropyldimethoxy-silane ~o triethylaluminum was l:0.9:7.5. Again, the weight of the titanium trichloride component of the catalyst system was 0.04 g.
The results of this example are tabulated in the Table.

WO 93/23162 2 1 3 5 ll O 1 P~/US93/04385 COMPARP.TIYE EXAMPLE 1 Example 1 was identically reproduced but for the composition of the catalyst system. The catalyst system of this comparative example omitted the silane component, isobutylisopropyldimethoxysilane. However, the molar ratio of titanium trichloride to triethylaluminum was identical to the molar ratio of these components in Example 1. That is, the molar ratio of titanium trichlaride to triethylaluminum was 1:4.6.
Otherwise, the polymerization reaction was conducted in exact accordance with the polymerization conditions that existed during the polymerization of Example 1.
Unfortunately, this example was run for only 20 minutes. The reason for this abbreviated testing per-iod was that the product produced was so sticky that stirring could not be maintained even at maximum power.

The polypropylene generated during the 20 mi~ute run was weighed to provide catalyst activity, albeit over this abbreviated 20 minute period. ~
Unfortunately, the stic~inéss~of the polypropylene product was such that the only physical property tha-t could be measured was an analysis of percent heptane insolubility of the polyprop~lene p~od~ct, which analysis was determined in accordan~e-with the procedure set forth in Example 1. That resuIt, in view of low crystallinity of the polypropylene product, could only be certain to the extent that the percent heptane insolubility of the polypropylene product was less than 85%. ~

WO 93/23162 2 1 3 5 ~ O 1 PC~/US93/04385 ~= A brlef su~unary of this example is included in the Table.

, -WO93/23162 2 1 3 ~ ~ O 1 PCT/US93/04385 In this example propylene was polymerized in accordance with the procedure set forth in Example 1.
However, the catalyst system utilized in this example substituted the complex TiCl3Ø33~1Cl3. The other components were identical with those of Example 1, viz-isobutylisopropyl-dimethoxysilane ~IBIP) and triethylaluminum (TEAL3, respectively. ~his catalyst system also differed from the catalyst system of Example 1 in that it included butyl benzoate (BBE) (0.25 mole).
The molar ratio of titanium compound to silane to aluminum compound to BBE, moreover, was 1:0.9:7.0:0.25, respectively. The TiC13.033AlC13 complex, furthermore, was introduced into the polymerization reactor after being ballmilled with the BBE component. As in all the previous examples the first catalyst component, in this example TiC1,Ø33AlCl3, was present in an amount of 40 mg.
The results of this example are tabulated in the Table.

WO93/23162 2 1 3 5 ~ O 1 PCT/US93/04385 EXAMPLE S

The po~ymerization reaction of Example 4 was reproduced but the silane utilized was isobutyltrimethoxysilane.
The results of this example are included in the Table.

~ .
:
_ W093/23162 -21- 2 1 3 5 4 ~ 1 PCT/Vs93/0438s A polymerization in accordance with Example 4 was identically reproduced but the silane was diisopropyldimethoxysilane.
The results of Example 6 are incorporated in the Table.

~, . i ..

.-,'-`- .
: --,. . .
._ I

WO93t23162 2 1 ~ ~ ~ O 1 PCT/US93/04385 A polymerization in accordance with Example 4 was reproduced. However, although the catalyst system of this example included TiCl3.AlCl3, as well as IBIP
and TEAL as components, this catalyst system did not include butyl benzoate (~BE). This catalyst system also differed from the catalyst system of Example 4 in that the molar ratio of titanium compound to silane to aluminum compound was l.0:0.9:lO.0, respectively.
Moreover, in this example the titanium ~ catalyst component was introduced into the pol~merization reac~or in an amount such that its total weight was 75 mg.
Finally, the reaction time was 2 hours inste~d of the l hour duration employed in Exampl~ 4.
The results of this example are tabulated in the Table.

. .

_ W093/23~62 -23- 2`1 ~ 5:~ 0 1 PCT/~S93/04385 ~- COMPARATIVE EXAMPLE 2 Example 4 was identically reproduced except for the omission of the silane component. That is, the catalyst system comprised the complex TiCl3Ø33AlCl3 (40 mg.), ballmilled with BBE, and triethylaluminum present in a molar ratio of the Ti complex to TEAL to BBE of 1:7.0:0.25.
An analysis of the polypropylene product of this reaction is summarized in the Table. It is noted that no val~es are provided for melt flow rate and bulk density. These physical properties could not be obtained because of the extremely low heptane insolubility of the polypropylene product. That is, the product obtained was too sticXy to provide accura~e measurement of these properties in accordance with the 3 standard ASTM tests under which these properties were measured.

. , ~ , W093/23162 2 1 3 5 ~ ~ 1 PCT/US93/0438~

Example 4 was reproduced except that it was conducted in accordance with prior art teachings. That is, although polymerization reac~ion conditions were identical with Example 4 and the catalyst system again comprised 40 milligrams of TiC13Ø33AlCl3, the aluminum-~ontaining compound was not txiethylaluminum but rather, in accordance with prior art teachings, diethyla~uminum chloride. As in Comparative Example 2, the molar ratio of the titanium compound to the organoaluminum compound, diethylaluminum chloride, was again l:7.0 with no silane present.
The results of this example are also inc~uded in the Table.

W ~ 93/23162 ~ 1 3 S i ~ lPCT/US93/0438S

TABLE
A. The CatalYst System Molar Ratio of Components , _ ; - .. .. _ = . = . ,. . _ _ Example TiCl.,. ¦ Total No. TiCl3 l/3AlCl~ IBIPl IBTMZ DIP3 BBE~ TEA~ ¦ Wt., _ _ _ __ _ _ .
1 _ 1 _ _ 0~5 _ 4~6_ 40 i 2 ~ 1 _ 0 ~ 7 _ _ _ 6 ~ 0 . 40 3 1 O~g __ . . 7 5_ 40 ~- I 1 - o g _ _. o.~s 4 6 40 l . . , I
1 5 . 1 . . 0-9_ 0.25 7 .0 40 I i : j 6 1: : 1 I : 0 9 0.25 7.0 40 I .
~ 77 1 0.9 10.0 75 .
`~ ce:~ -~ ~ 1 ; _ 0~2S 7~0 40 CE3 l 1 r-- 0 ~ 25 _ 40 PolYmerization Conditions: Footnotes:
Time: -1 hour 'Isobutylisopropyldimethoxysilane Tem~.- 70C- 71sobutyltrimethoxysilane Pressure 460 psig ~Diiso~ropyldimethoxysilane ~ Hydrogen: 400 ml Butylbenzoate :~ Stirring: 400:rpm -'Triethylaluminum ~:~ Total-Ti-G~nt2~ning Component ~Diethylaluminum chloride Wt: 40 mg~ 'Tot~l Ti-Containing Component Wt: 75 mg. and 2-hour polymerization _, - J

-- _ . _ _ . _ .

W O 93/23162 ~ 1 3 ~ 4 0 1 P~r/US93/04385 -26-B. PolYpropvlene Reaction and Product . _ _ . -- .- . _ .
Example Activity, MFR,g/10 ¦ Bulk Dens., No . g . PP/g . Cat . Ti ,ppm ~ ~lI min .I lb . /f t~ ' _ _ _ _ , . -1 5,~50 ~2 94 7 2.4 27.0 2 6,15G 51 97.75 0.8 25.5 , __ _ . .- . .
3 6,820 47.5 99.5 0.7 26.7 .. . ., ~El 3,200- _ <85 _ . .~ .
. -4 5,625 40 96.5 1.018.6 _ 2,600 ~9 _ 94.5 2.0 18.0 6 5,625 _ 38 97 S 1.0_ 20 _ , __ 7 1,640 149_ ~0.6 3.5 18.0 _ . ~
CE2 2,000 120 85.0 I
. ¦ -- CE3 1,900 124 97.4 _ 7.0 20.2 *Could not be processed.

-213.5~01 ANALYSIS OF RESULTS

An analysis of. the Table establishes that the examples within the contemplation of the catalyst system of the present invention produce acceptable catalyst activities. Moreover, the isotacticity, as m~asured by percent heptane insolubility, is superior to that of the examples utilizing .prior art catalyst systems. Indeed, Comparative Examples l and 2, because of the low level of isotacticity in the polypropylene product, could not be processed~
~ The only exception to the above remarks is the comparison between Example 7 and Comparative ~.xample 3.
These two examples differed by the presence in the catalyst system of Example 7 of the silane IBIP which silane was not present in the catalyst system of Comparative Example 3. In addition, the aluminum compound of Example 7, in accordance with the present invention~, was a trialkylaluminum compound, TEAL, .
whereas~the~a1uminum compound of the catalyst system of Comparat:ive~Example 3 was diethylaluminum chloride.
The aatalyst system of Comparative Example 3 had marginally:improved catalyst~activity compared to the catalyst:system~of Example 7. However, ~he degree of po~ymerization of the:polypropyle~e produced using the;catalyst-~-syçtem-of~ Comparative Example 3 was significantly lower than tne polypropylene produced using the catalyst system of Example 7. This is manifested by the.melt flow rate which, as those skilled in the art are aware, is a measure of polymer viscosity, which is proportional to the degree of polymerization.
_ I

W093/23 2 213~401 16 PCl /US~3/04385 The lower the melt ~low rate the greater the polypropylene viscosity.

:

Claims

WHAT IS CLAIMED IS:

1. A cocatalyst comprising an aluminium trialkyl and an alkoxysilane for use in preparing a catalyst system for the polymerization of olefins containing a titanium III component and an election donor having an ultraviolet absorption wave length of less than 250 nanometers.

2. The cocatalyst of Claim 1, wherein the alkoxy silane has the structural formula of (OR1)4-p-qSiR2pR3q, where R1 is hydrocarbyl; R2 and R3 are the same or different and are hydrocarbyl; p is 0 or an integer of 1 or 2; and q is an integer of 1 to 3, with the proviso that the sum of p and q does not exceed 3.