Note: Descriptions are shown in the official language in which they were submitted.
214~538
W O 94/07926 PC~r/US93/09009
DESCRIPTION
PROCESS FOR POLYMERIZING ALPHA-OLEFIN
~- Technical Field
This invention relates to a process for producing
highly stereospecific ~-olefin polymers. More particularly,
the invention relates to a process that utilizes a novel high
activity stereoregular polymerization catalyst system to
produce ~-olefin polymers having improved properties.
Background Art
The use of a solid, transition-metal based, olefin
polymerization catalyst system including a magnesium-
containing, titanium halide-based catalyst component to
produce a polymer of an ~-olefin such as ethylene, propylene,
and butene-1, is well known in the art. Such polymerization
catalyst systems are typically obtained by the combination of
a titanium halide-based catalyst component, an organoaluminum
compound and one or more electron donors. For convenience of
reference, the solid titanium-containing catalyst component
is referred to herein as "procatalyst", the organoaluminum
compound, as "cocatalyst", and the electron donor compound,
which is typica~ly used separately or partially or totally
complexed with the organoaluminum compound, as "selectivity
control agent" (SCA). It is also known to incorporate
electron donor compounds into the procatalyst. The electron
donor which is incorporated with the titanium-containing
compounds serves a different purpose than the electron donor
modifier referred to as the selectivity control agent. The
compounds which are used as the electron donor may be ~he
same or different compounds which are used as the selectivity
control agent. The above-described stereoregular high
activity catalysts are broadly conventional and are described
in numerous patents and other references including Nestlerode
et al, U. S. Patent 4,728,705, which is incorporated herein
by reference.
Although a broad ra~ge of compounds are known
generally as selectivity control agents, a particular
214S538
-2-
catalyst component may have a specific compound or groups of
compounds with which it is specially compatible. For any given
procatalyst and/or cocatalyst, discovery of an appropriate type
or selectivity control agent can lead to significant increases
5 in catalyst efficiency, lower hydrogen demand as well as the
improvement in polymer product properties.
Many classes of selectivity control agents have
beer. disclosed for possible use in polymerization catalysts.
One class of such selectivity control agents is the class of
10 organo-silanes. For examples, Hoppin et al, U.S. Patent
4,990,478, describes branched C3 - Clo alkyl-t-
butoxydimethoxysilanes. Other aliphatic silanes are described
in Hoppin et al, U.S. Patent 4,829,038. EP-A-0459009 discloses
the use of a solid catalyst prepared under special conditions
15 from diethoxy magnesium, titanium tetrachloride and phthaloyl
chloride along with a specific silicon compound and a specific
organoaluminium compound.
Although many methods are known for producing
highly stereoregular ~-olefin polymers, it is still desired to
20 improve the activity of the catalyst and produce polymers or
copolymers that exhibit improved properties such as broad
molecular weight distribution, and low zylene solubles.
Further, it is desired to produce polymers or copolymers that
exhibit a reduction in the amount of volatiles, e.g. smoke
25 and/or oil, liberated during subsequent processing, e.g.
extrusion.
Disclosure of the Invention
The invention relates to a process for the
production of homopolymers or copolymers that have improved
30 polymer properties.
More particularly, the present invention is a
process for the production of polymers using a high activity
olefin polymerization catalyst system which comprises (a) a
titanium halide-containing procatalyst components obtained by
35 halogenating a magnesium compound, typically of the formula
2~R'R'', wherein R' and R'' are, independently, an alkoxide,
aryloxide or hydrocarbyl carbonate group or halogen, especially
-214S~38
-2a-
alkoxide groups of 1 to 10 carbon atoms with a halogenated
tetravalent titanium compound in the presence of a
polycarboxylic acid ester electron donor, and a
- halohydrocarbon, (b) an organoaluminum cocatalyst
21~5~8
Jmponent, and (c) an organosilane selectivity control agent
naving the general formula:
Rl R3
\si/
R2/ \R4
wherein Rl, R2 and R3 are, independently, alkyl of 1 to 12
- carbon atoms, aryl of 1 to 12 carbon atoms, alkaryl of 1 to.
12 carbon atoms, aralkyl of 1 to 12 carbon atoms or halogens
and R4 is a hydrocarbyloxy Gf 1 to 2 carbon atoms. The
preferred selectivity control agents are t-
butyld imethylmethoxys i lane, ( 2 -methyl-2 -
butyl) dimethylmethoxysilane, (3-ethyl-3-pentyl) -
dimethylmethoxysilane and mixtures thereof.
Best Mode for Carryinq Out the Invention
lS Although a variety of chemical compounds are useful
for the production of the procatalyst, a typical procatalyst
of the invention is prepared by halogenating a magnesium
compound of the formula MgR'R", wherein R' is an alkoxide or
aryloxide group and R" is an alkoxide, hydrocarbyl carbonate
or aryloxide group or halogen, with a halogenated tetravalent
titanium compound in the presence of a halohydrocarbon and an
electron donor.
The magnesium compound employed in the preparation
of the solid catalyst component contains alkoxide, aryloxide,
25 hydrocarbyl carbonate or halogen. The alkoxide, when present,
generally contains from 1 to 10 carbon atoms. Alkoxides
containing from 1 to 8 carbon atoms are preferable, with 2 to 4
carbon atoms being more preferable. The aryloxide, when
present, generally contains from 6 to 10 carbon atoms, with 6
30 to 8 carbon atoms being preferred. When halogen is present, it
is preferably present as bromine, fluorine, iodine or chlorine,
with chlorine being more preferred. Preferred magnesium
compounds are magnesium dialkoxides.
Suitable magnesium compounds are magnesium
35 chloride, ethoxy magnesium bromide, isobutoxy magnesium
chloride, phenoxv magnesium iodide, cumyloxy magnesium
bromi~e magnesium diethoxide, magnesium iscpropcxide,
~ 2145~38
magnesium ethyl carbonate and naphthoxy magnesium chloride.
The preferred magnesium compound is magnesium diethoxide.
Halogenation of the magnesium compound with the
halo-genated tetravalent titanium compound is usually effected
by employing an excess of the titanium compound. At least 2
moles o~ the titanium compound should ordinarily be employed
per mole o~ the magnesium compound. Preferably from 4 moles
to 100 moles of the titanium compound are employed per mole
of the magnesium compound, and most preferably from 4 moles
to 20 moles of the titanium compound are employed per mole of
the magnesium compound.
Halogenation of the magnesium compound with the
halogenated tetravalent titanium compound is typically effected
by contacting the compounds at an elevated temperature in the
range from about 60~C to about 150~C, preferably from about
70~C to about 120C. Usually the reaction is allowed to
proceed over a period of 0.1 to 6 hours, preferably between
0.5 to 3.5 hours. The halogenated product is a solid
material which is isolated from the liquid reaction medium
by filtration, decantation or a suitable method.
The halogenated tetravalent titanium compound
employed to halogenate the magnesium compound contains at
least two halo~en atoms, and preferably contains ~our halogen
atoms. The halogen atoms are chlorine atoms, bromine atoms,
iodine atoms or fluorine atoms. The halogenated tetravalent
titanium compounds generally has up to two alkoxy and/or
aryloxy groups. Examples of suitably halogenated tetravalent
titanium compounds include diethoxytitanium dibromide,
isopropoxytitanium triiodide, dihexoxytitanium dichloride,
phenoxytitanium trichloride, titanium tetrachloride and
titanium tetrabromide. The preferred halogenated tetravalent
titanium compound is titanium tetrachloride.
Halogenation of the magnesium compound with the
halogenated tetravalent titanium compound, as noted, is con-
ducted in the presence of a halohydrocarbon and an electrondonor. If desired, an inert hydrocarbon diluent or solvent
may also be present, although Ihis is not necessary.
2145538
W094/07926 PCT/US93/09009
The halohydrocarbon employed is an aromatic or
aliphatic including cyclic and alicyclic compounds.
Preferabl~ the halohydrocarbon contains 1 or 2 halogen atoms,
although more may be present if desired. It is preferred
that the halogen, independently, is chlorine, bromine or
fluorine. Suitable aromatic halohydrocar~ons include
chlorobenzene, bromobenzene, dichl~robenzene,
dichlorodibromobenzene, o-chlorotoluene, chlorotoluene,
dichlorotoluene, chloronaphthalene. Chlorobenzene, o-
chlorotoluene and dichlorobenzene are the preferredhalohydrocarbons, with chlorobenzene and o-chlorotoluene
being more preferred.
The aliphatic halohydrocarbons which can be
employed suitably of 1 to 12 carbon atoms. Preferably such
halohydrocarbons of 1 to 9 carbon atoms and at least 2
halogen atoms. Most preferably the halogen is present as
chlorine. Suitable aliphatic halohydrocarbons include
dibromomethane, trichloromethane, 1,2-dichloroethane,
trichloroethane, dichlorofluoroethane, hexachloroethane,
trichloropropane, chlorobutane, dichlorobutane,
chloropentane, trichloro-fluorooctane, tetrachloroisooctane,
dibromodi-fluorodecane. The preferred aliphatic
halohydrocarbons are carbon tetrachloride and
trichloroethane.
Aromatic halohydrocarbons are preferred,
particularly those of 6 to 12 carbon atoms, and especially
those of 6 to 10 carbon atoms.
Typical electron donors that are incorporated
within the procatalyst include esters, particularly aromatic
esters, ethers, particularly aromatic ethers, ketones,
phenols, amines, amides, imines, nitriles, phosphines,
phosphites, stibines, arsines, phosphoramides and
alcoholates. Alkyl esters of aromatic polycarboxylic acids
are frequently incorporated into electron donors.
Illustrative of such electron donors are methyl benzoate,
ethyl benzoate, diethyl phthalate, diisoamyl Phthalate, ethyl
p-ethoxybenzoate, methyl p-ethoxybenzoate, diisobutyl
- 2115~38
phthalate, dimethyl napthalene-dicarboxylate, diisobutyl
maleate, diisopropyl terephthalate, and diisoamyl phthalate.
Diisobutyl phthalate is the preferred alkyl ester of
aromatic carboxylic acid.
After the solid halogenated product has been separated
frcm the liquid reaction medium, it is usually treated one or
more times with additional halogenated tetravalent
titanium compound in order to remove residual al~oxy and/or
aryloxy grGups and ~xi~ize catal~yst activity. Preferably,
the halogenated product is treated multiple times with
separate portions of the halo-genated tetravalent titanium
compound. Better results are obtained if the halogenated
product is treated twice with separate portions of the
halogenated tetravalent titanium compound. As in the initial
halogenation, at least 2 moles of the titanium compound
should ordinarily be employed per mole of the magnesium
compound, and preferably from 4 moles to 100 moles of the
titanium compound are employed per mole of the magnesium
compound. Most preferably from 4 moles to 20 moles of the
titanium compound per mole of the magnesium compound.
Optionally, the solid halogenated product is
treated at least once with one or more acid chlorides after
washing the solid halogenated product at least once with
additional amounts of the halogenated tetravalent titanium
2S compound. Suitable acid chlorides include benzoyl chloride
and phthaloyl chloride. The preferred acid chloride is
phthaloyl chloride.
The reaction conditions employed to treat the solid
halogenated product with the titanium compound can be the same
as those employed during the initial halogenation of the
magnesium compound.
After the solid halogenated product has been
treated one or more times with additional halogenated
tetravalent titanium compound, it can be separated from the
liquid reaction medium, washed at least once with an inert
hydrocarbon of up to 10 carbon atoms to remove unreacted
titani~lm compounds, zn~ dried Exemplary of ~he inert
2~4~38
hydrocarbons that are suitable for the invention are
isopentane, isooctane, hexane, heptane and cyclohexane.
~ he final washed product usually has a titanium
content of from 0 . 5 percent by weight to 6 . 0 percent by weight,
5 preferably from 2 . 0 percent by weight to 4 . 0 percent by weight
The atomic ratio of titanium to magnesium in the rinal product
is usually between 0 . 01:1 and 0 . 2 :1, preferably between 0 . a2 :1
and 0 . 0 :1.
The cocatalyst is an organoaluminum compound which
10 is tvpically an alkylaluminum compound. Suitable
alkylaluminum compounds include trialkylaluminum compounds,
such as triethyl-aluminum or triisobutylaluminum; includinq
dialkylaluminum halides such as diethylaluminum chloride and
dipropylaluminum chloride; and dialkylaluminum alkoxides such
15 as diethylaluminum ethoxide. Trialkylaluminum compounds are
preferred, with triethylaluminum being the preferred
trialkylaluminum compound.
The organosilane selectivity control agents in the
catalyst system contain at least one silicon-oxygen-carbon
20 lin~age Suitable organosilane compounds includes compounds
having the following general formula:
Rl R3
\si/
R2 / \ R4
25 wherein Rl, R2 and R3 are, independently, alkvl of I to 12
carbon atoms, aryl group of 1 to 12 carbon atoms, alkaryl
group of 1 to 12 carbon atoms, aralkyl group of from 1 to 12
carbon atoms or halogen; and R4 is a hydrocarbyloxy group of
to 2 carbon atoms . It is pref erred that Rl, R2, and R3 are
3 0 alkyl groups and R4 is a alkoxy group . It is further
preferred that R4 is a methoxy group. Examples of suitable
organosilane selectivity control agents include t-
butyldimethyl-methoxys i lane, ( 2 -methyl-2 -
butyl) dimethylmethoxysilane, (3-ethyl-3-pentyl) -
35 dimethylmethoxysilane and mixtures thereof. The preferredorgznosilane selectivity control agent is t-
butvldi;nethylmethoxysilane The invention also contemplates
21~5538
the use of mixtures of two or more selectivity control
agents. The selectivity control agent is provided in a
quantity such that the molar ratio or the selectivity control
agent to the titanium present in the procatalyst is ~rom
about 2 to about 60. Molar ratios rrom about 8 to about 45
are pre~erred, with molar ratios from about 10 to about 35
being more preferred.
The hig~ activity stereoregular polymerization
cata-lyst is employed in a chemical reaction to effect
lo polymerization by contacting at least one ~-olefin under
polymerization condi-tions. In accordance with the
invention, the procatalyst component, organoaluminum
cocatalyst, and selectivity control agent can be in~roduced
into the polymerization reactor separately or, i~ desired,
two or all of the components may be partially or completely
mixed with each other before they are introduced into the
reactor. In any event, the organoaluminum cocatalyst is
employed in sufficient quantity to provide from, say, 1 mole to
about 150 moles of aluminum per mole of titanium in the
procatalyst It is preferred that the cocatalyst is present
in sufficient quantities to provide from 10 moles to about
100 moles of aluminum per mole of titanium in the
procatalyst.
The particular type of polymerization process
utilized is not critical to the operation of the present
invention and the polymerization processes now regarded as
conventional are suitable in the process of the invention.
The polymerization is suitably conducted under polymerizatiOn
conditions as a liquid phase or a gas-phase process employing
a fluidized catalyst bed.
The polymerization conducted in the liquid phase
usually employs as reaction diluent an added inert liquid
diluent or alternatively a liquid diluent which comprises the
olefin, such as propylene or 1-butene, undergoing
polymerization. If a copolymer is prepared wherein ethylene is
one of the monomers, ethylene is introduced by conventional
means. Typical polymerization conditions include a reaction
214~538
temperature from about 2SC to about 125C, with temperatures
from about 35C to about 90C being preferred and a pressure
su~icient to maintain the reacliOn mixture in a liquid
phase. Such pressures are from about 150 psi to about 1200
S psi, with pressures from about 2S0 psi to about 900 psi are
preferred. The liquid phase reaction is operatea in a
batchwise manner or as a continuous or semi-con~inuous
process. Subsequent to reaction, the polymer product is
recovered by conventional procedures. The precise controls
of the polymerization conditions and reaction parameters of
the liquid phase process are within the skill of the art.
As an alternate embodiment of the invention, the
polymerization may be conducted ir. a gas phase process in the
presence of a fluidized catalyst bed. One such gas phase
process polymerization process is described in Goeke et al,
U.S. Patent 4,379,7S9, incorporated herein by reference. The
gas phase process typically involves charging to reactor an
amount of preformed polymer particles, gaseous monomer and
separately charge a lesser amount of each catalyst component.
Gaseous monomer, such as propylene, is passed through the bed
of solid particles at a high rate under conditions of
temperature and pressure sufficient to initiate and maintain
polymerization. Unreacted ole~in is separated and recovered
and polymerized olefin particles are separated at a rate
substantially equivalent to its production. The process is
conducted in a batchwise manner or a continuous or semi-
continuous process with constant or intermittent addition of
the catalyst components and/or ~-olefin to the polymerization
reactor. Typical polymerization temperatures for a gas phase
process are from about 30C to about 120C and typical
pressures are up to about 1000 psi, with pressures from about
100 to about S00 psi being preferred.
In both the liquid phase and the gas-phase poly-
merization processes, molecufar hydrogen is generally added to
the reaction mixture as a chain transfer agent to regulate the
molecular weight of the polymeric product. Hydrcgen is
typically employed for this purpose in a manner well known to
~ 21~5538
W094/07926 PCT/US93/09009
persons skilled in the art. The precise control of reaction
conditions, the rate of addition of feed component and
molecular hydrogen is broadly within the skill of the art.
The present invention is useful in the
polymerization of ~-olefins of up to 10 carbon atoms,
including mixtures thereof. It is preferred that ~-olefins
of 3 carbon atoms to 8 carbon atoms, such as propylene,
butene-l and pentene-1 and hexane-l, are polymerized. If ~-
olefins are to be copolymerized, the preferred ~-olefins
include ethylene.
The polymers produced according to this invention
are predominantly isotactic. Polymer yields are high
relative to the amount of catalyst employed. The process of
the invention produces homopolymer and copolymers including
both random and impact copolymers, that have a relatively
broad molecular weight distribution while maintaining a
relatively low oligomers content (determined by the weight
fraction of C2l oligomer) of less than 180 ppm. The
production of polymers having an oligomers content of less
than 130 ppm is preferred, with an oligomers content of less
than 115 ppm being more preferred.
Other features, advantages and embodiments of the
invention disclosed herein will be readily apparent to those
exercising ordinary skill after reading the foregoing
disclosure. In this regard, while specific embodiments of
the invention have been described in detail, variations and
modifications of these embodiments can be effected without
departing from the spirit and scope of the invention as
described and claimed.
The invention described herein is illustrated, but
not limited by the following Illustrative Embodiments and the
Comparative Example. The following terms are used throughout
the Illustrative Embodiments and Comparative Example:
SCA (selectivity control agent)
PEEB (ethyl p-ethoxybenzoate)
TBDMMS (t-butyldimethylmethoxysilane)
NPTMS (n-propyltrimethoxysilane)
DIBDMS (diisobutyldimethoxysilane)
DIBDES (diisobutyldiethoxysilane)
W094/07926 2 1 ~ 5 5 3 8 PCT/US93/09009
ILLUSTRATIVE EMBODIMENT I
(a) Preparation of Procatalyst Component
The procatalyst was prepared by adding magnesium
diethoxide (2.17 g, 19 mmol) to 55 ml of a 50/50 (vol/vol)
mixture of TiCl4/chlorobenzene. After adding diisobutyl
phthalate (0.66 ml, 2.50 mmol), the mixture was heated in an
oil bath and stirred at 110C for 60 minutes. The mixture
was filtered hot and slurried in 55 ml of a 50/50 (vol/vol)
mixture of TiCl4/chlorobenzene. Phthaloyl chloride (0.13 ml,
0.90 mmol) was added to the slurry at room temperature. The
resulting slurry was stirred at 110C for 60 minutes,
filtered, and slurried again in a fresh 50/50 mixture of
TiCl4/chlorobenzene. After stirring at 110C for 30 minutes,
the mixture was filtered and allowed to cool to room
temperature. The procatalyst slurry was washed 6 times with
125 ml portions of isooctane and then dried for 120 minutes,
at 25C, under nitrogen.
(b) Polymerization of Propylene
Various catalysts were produced using several
organosilanes as the selectivity control agent, some of which
are within the scope of the invention (TBDMMS) and others
that are not within the scope of the invention (NPTMS, DIBDES
and DIBDMS). Propylene (2700cc) and molecular hydrogen were
introduced into a 1 gallon autoclave. The temperature of the
propylene and molecular hydrocarbon was raised to 67C. An
organosilane selectivity control agent, triethylaluminum, and
the procatalyst slurry produced above were premixed for about
20 minutes and then the mixture was introduced into the
autoclave. The amount of silane utilized in the
polymerization also varied. The amount of triethylaluminum
(0.56 mmoles) and the amount of the procatalyst slurry
(sufficient quantity of procatalyst to provide 0.008 mmoles
of titanium to the autoclave) remained constant. The
autoclave was then heated to about 67C and the
polymerization was continued at 67C for one hour. The
polypropylene product was recovered from the resulting
mixture by conventional methods and the weight of the product
wo 94/07922 ~ 4~S 3 8 PCI`/US93/09009
was~used to calculate the reaction yield in millions of grams
of polymer product per gram (MMg/g) of titanium in the
procatalyst. The term "Q" was calculated as the quotient of
the weight average molecular weight (Mw) and the number
5 average molecular weight (Mn)~ determined by gel permeation
chromatography. The term ''Mz'' as defined in "Encyclopedia of
Polymer Science and Engineering, 2nd Edition", Vol. 10, pp.
1-19 (1987) incorporated herein by reference, is the z-
average molecular weight. The term "R";was calculated as the
10 quotient of Mz and Mw. "Melt Flow" is determined according
to ASTM D-12~8-73, condition L. "Xylene Solubles" were
determined in accordance with U.S. Food and Drug
in;stration Regulations, 21 CFR 177.1520. The results of
a series of polymerizations are shown in TABLE I.
TABLE I
H2 Yield XS3
SCA MFmmoles MMq/g Mzx 10-3 f% wt) Q R
TBDMMS 3.527 1.2 1560 5.0 9.9 4.3
TBDMMS 2.327 1.0 1570 3.8 9.6 3.9
NPTMSl 2.234 0.88 1510 2.4 7.3 3.9
20DIBDES 5.223 0.87 2070 lo.o 8.0 5.4
DIBDMSI 3.534 1.10 1560 3.8 8.2 4.3
l Comparison
2 mmoles of hydrogen added to the liquid phase reactor system
3XS = Xylene solubes by % weight
To further illustrate the advantages obtained using
the catalyst system of the invention, viscosity ratio values
were taken for polymers having a melt flow of about 3 dg/min
using the smooth curves (viscosity ratio vs. melt flow).
"Viscosity Ratio" was determined by cone and plate rheometry
(dynamic viscosity measurements) as a ratio of the viscosity
of the product at a frequency of 0.1 Hz divided by the
viscosity of the product at a frequency of 1.0 Hz. As the
viscosity ratio of polymer product increases, the molecular
W094/07926 2 1 ~ 5 5 3 8 PCT/US93/09009
weight distribution increases. The values are shown in TABLE
II.
Table II
- SCA Viscosity Ratio at 3 dq/min
TBDMMS 1.75
NPTMSI 1.56
DIBDMSI 1.56
~For comparison
It is seen from TABLE II that the catalyst systems
of the invention direct a higher viscosity ratio and
therefore a broader molecular weight distribution than a
conventional catalyst systems using NPTMS as the selectivity
control agent.
ILLUSTRATIVE EMBODIMENT II
Injection Molding of Polypropylene Product
Some of the polypropylene products, produced
according to Illustrative Embodiment I, were recovered by
conventional means. Each recovered product was mixed and
pelletized with the following additives package: 1000 ppm of
Irganox~ 1010 hindered phenolic primary antioxidant, 1000 ppm
of Irgafos~ 168 phosphite secondary antioxidant and 500 ppm
of Calcium stearate as an acid acceptor. The pelletized
polymer products were injection molded in an Arburg Injection
Molder. The final "melt temperature" (Tmt, C) is obtained
from a differential scanning calorimetry curve for each
polymer product produced. A higher melt temperatu~e
correlates to higher isotacticity of the polymer product.
The "Oligomers Content" was determined by the
overnight extraction of a polypropylene sample in a~ 30 chloroform solution containing hexadecane (n-CI6) as an
internal standard. An aliquot of the extract is shaken in
, methanol and filtered to remove trace amounts of atactic
material. The filtered liquid is then injected onto a
capillary column which uses a flame ionization gas
W094/07926 2 1 4 5 5 3 ~ PCT/US93/09oO9--
chromatograph. Relative amounts of the extracted components
are calculated based on the weight of polymer extracted using
the internal standard quantitation against the C2l oligomer
groups. The oligomers content is an indicator of the amount
of volatiles, e.g. smoke and/or oil that will be liberated by
the polymer during extrusion. For instance, a lower
oligomers content for a polymer product translates into lower
smoke generation during further processing (e.g. extrusion)
of the polymer product for film and tèxtile applications.
The results of the various analysis of polymer products are
shown in Table IV.
Comparative Example
(a) Preparation of Procatalyst Component
The procatalyst was prepared by adding magnesium
diethoxide (50 mmol) to 150 ml of a 50/50 (vol/vol) mixture
of chlorobenzene/TiCl4. After adding ethyl benzoate (16.7
mmol), the mixture was heated in an oil bath and stirred at
110C for approximately 30 minutes. The resulting slurry was
filtered and slurried twice with 150 ml of a fresh 50/50
(vol/vol). Benzoyl chloride (0.4 ml) was added to the final
slurry. After stirring at 110C for approximately 30
minutes, the mixture was filtered. The slurry was washed six
times with 150 ml portions of isopentane and then dried for
90 minutes, at 30C, under nitrogen.
(b) Polymerization
Using the above-described procatalyst (section a),
propylene was polymerized as described in Illustrative
Embodiment II, section (b), except the selectivity control
agent was PEEB.
The resulting polypropylene product was mixed,
pelletized and injection molded as described in Illustrative
Embodiment III. The results are furnished in TABLE III.
, ,~
14
W094/07926 2 1 ~ 5 ~ 3 8 PCT/US93/09009
TABLE III
21 Carbon Melt
Oligomer Count Flow
SCA Tmt(C)l (pPm) dq/min
- TBDMMS 170.8 102 2.3
NPTMS2 160.3 54 2.4
NPTMS3 169.5 76 3.3
DIBDMS2 169.2 80 2.3
PEEB3 169 260 2.9
~Final melt temperature (C) was obtained by differential
scanning calorimetry (DSC) according to ASTM D-3417-83.
2For comparison
3Comparative catalyst system
