Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Background of the Invention
The present invention relates to olefin polymeriza-
tion catalyst compositions comprising a magnesium hal de and
a til:anium halide and to a process for the polymerization of
olefins usiny such catalyst compositions.
Numerous proposals are known from the prior art to
provide olefin polymerization catalysts obtained by combining
a component comprising magnesium halide and a titanium halide
with an activating organoaluminum compound. The polymeriæation
activity and the stereospecific performance o such compositions
may be improved by incorporating an electron donor (Lewis
base) into the component comprising titanium, into the organo-
aluminum activating component or into both these components.
The catalyst compositions of this type which have been disclosed
in the prior art are able to produce olefin polymers in an
attractive high yield, calculated as g polymer/g titanium, and
also with the required high level of stereoregular polymeric
material O
The manufacture of magnesium halide supported
catalysts for the polymerization of olefins by halogenating a
magnesium alkoxide is well known. See United States Patents
4,400,302 and 4,414,132 to ¢oodall et al. Since tha morphology
of the polymer is generally controlled by the morphology of
the catalyst, much effort has been expended in attempting to
control the morphology of such catalysts. Magnesium alkoxides
have been formed~by metathesis and/or have been all built to
obtain the desired particle size, distribution and bulk density.
These methods are costly and time consuming. Thus, there is
- a need for a simplified method for producing such catalysts
but which still allows adequate morphology control.
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The present invention provides a simplified means or
morphology control for magnesium alkoxide catalyst particles.
The magnesium alkoxide is simply formed rom a chemical reaction
between a mixture o an alkyl or aryl magnesium compound and a
branched or aromatic aldehyde or a mixture of two or more alkyl
or aryl magnesium compounds and an aldehyde or ketone. The
use of such aldehydes, mixed magnesium alkyls or aryls forms a
mixture of magnesium alkoxides which is e~tremely soluble in
organic solvents because of antropic effects. Others have pre-
pared soluble magnesium alkoxide catalyst components by forminga complex of the magnesium alkoxide and a compound of another
metal, such as aluminum, zinc or boron. United States Patents
4,496,660; 4,496,661 and 4,526,943 disclose such complexes with
other metal compounds. The present invention provides a soluble
magnesium alkoxide catalyst component without the necessity of
the addition of another metal compound to make it soluble.
Summary of the In~ention
The present invention relates to a solid catalyst
component consisting of particles with a narrow particle size
distribution which is prepared (a) by mixing an alkyl or aryl
magnesium compound with a branched or aromatic aldehyde in the
pr~sence of a solvent or (b~ by mixing two or more alkyl or aryl
maynesium compounds with an aldehyde or ketone in the presence
of a solvent, then adding a tetravalent titanium halide to the
solution,-recovering the resulting precipitate, and then con-
i tacting the precipitate with a tetravalent titanium halide. An
electron donor and/or a halohydrocarbon may also be added to the
i solution along with the tetravalen-~ titanium halide. No inert
; .~
support material is present in the component.
Detailed Description of the Invention
.~
The primary goal of the present invention is to make
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soluble magnesium alkoxides which can be used in the production
of polymerization catalysts with improved morphology. In many
cases, the direct reaction of a magnesium alkyl or aryl and an
aldehyde or a ketone results in a product which is not soluble.
Soluble magnesium alkoxides can be obtained by choosing the
reactants from specific groups which together create entropic
I effects which encourage the solubility of the magnesium alkoxide
- product.
- Preferred magnesium compounds are selected from
dialkyl and diaryl ma~nesium compounds and alkyl aryl magnesium
compounds. In such compounds the alkyl groups preferably have
from 2 to 20 carbon atoms. Examples of these preferred groups
of compounds are diethyl magnesium, dibutyl magnesium, di-n.amyl
magnesium, dicyclohexyl magnesium, diisopropyl magnesium, iso-
butylpropyl magnesium, octylisoamyl magnesium, ethylheptyl
magnesium, naphthylphenyl magnesium, cumylphenyl magnesium, di-
phenyl magnesium, ethylphenyl magnesium and isobutylnaphthyl
magnesium.
As discussed abova, there must be an alkyl or aryl
magnesium compound present in the solution in order to obtain
proper entropic effects for good solubility of the alkoxides
; formed in the solution. Any of the above-described the alkyl
or aryl magnesium compounds may be used to form the solid
catalyst component of the present invention. Preferred mixtures
include n-butyl-isobutyl magnesium and dialkyl magnesium
containing alkyls from C2 to C20 (with the peak at C~ to C8).
~;; In alternative (a) above mixture of the above
~!
;. magnesium compounds with a branched or aromatic aldehyde will
create the conditions necessary for the formation of soluble
magnesium alk~xides. The preferred branched aldehyde is 2-
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- 3a - 61815-3241
ethylhexanal and the preferred aromatic aldehyde is benzal-
; dehyde. A large portion of the branched or aromatic aldehyde
may be replaced by a linear aldehyde. ThiS is desirable because
; branched and aromatic aldehydes are generally very expensive
compared to many linear aldehydes, such as acetaldehyde, butyral-
dehyde and octylaldehyde. Other examples of the many linear
aldehydes which can be used include paraformaldehyde, propion-
aldehyde and valeraldehyde. Linear aldehydes can be used to
replace as much as 70% and perhaps more of the branched or
aromatic aldehyde and the result will still be a magnesium
alkoxide solution which is like water.
In alternative (b) above, the aldehydes or ketones
must be included in the solution in order to form the magnesium
alkoxides. Specific examples of aldehydes are paraformalde-
hyde, acetaldehyde, propionaldehyde, butyraldehyde and valer-
aldehyde. Specific examples of such ketones include acetone
and 2-butanone.
The solvent used for the solution of the magnesium
alkyl or aryl compound and the aldehy~e or ketone is generally
~; 20 any non-reacti~e solvent which will form a homogeneous solution
and which wil~l also dissolve or at
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least disperse or suspend the tetravalent titanium halide. The preferred
solvents for use herein are isopentane, isooctane, hep-tane, chlorobenzene
and toluene.
In the halogenation with a halide of tetravalent titanium, the
magnesium compounds are preferably reacted to form a magnesium halide in
which the atomic ratio of halogen to magnesium is at least 1.2. Better
results are obtained when the halogenation proceeds more completely, i.e.
yielding magnesium halides in which the atomic ratio of halogen to
chlorine is at least 1.5. The most preferred reactions are those leading
to fully halogenated reaction products, i.e. magnesium dihalides. Such
halogenation reactions are suitably effected by employing a molar ratio
of magnesium compound to titanium compound of 0.005 to 2.0 preferably
~ 0.01 to 1Ø These halogenation reactions may proceed in the additional
; presence of an electron donor and/or an inert hydrocarbon diluent or
solvent. It is also possible to incorporate an electron donor into the
halogenated product.
Suitable halides of tetra-valent titaniums are aryloxy- or
alkoxydi- and -trihalides, such as dihexanoxytitanium dichloride,
diethoxytitanium dibromide, isopropoxytitanium tri~odide, phenoxytitanium
trichloride 9 and titanium tetrahalides, preferably titanium
tetrachloride.
Suitable halohydrocarbons are compounds such as butyl chloride,
phenyl chloride, naphthyl chloride, amyl chloride, but more preferred are
hydrocarbons which comprise from about 1 to 129 particularly less than 9,
carbon atoms and at least two halogen atoms. Examples of this preferred
group of halohydrocarbons are dibromomethane, trichloromethane,
1,2-dichloroethane, dichlorofluoroethane, trichloropropane~ dichloro-
dibromodifluorodecane, hexachloroethane and tetrachloroisooctane.
Chlorobenzene is the most preferred halohydrocarbon.
The halogenation normally proceeds under formation of a solid
reaction product which may be isolated from the reaction medium by
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filtration, decantation or another suitable method and subsequently
~ washed with an inert hydrocarbon diluen~ such as n-hexane, isooctane or
; toluene, to remove any unreacted material, including physically adsorbed
halohydrocarbon. As compared with the catalyst compositions which are
prepared by halogenating magnesium compounds with a titanium tetrahalide,
the presence of the halohydrocarbon during halogenation of the magnesi
compound brings about an increase in the polymerization activity of the
resulting catalyst compositions. The halogenated magnesium compounds are
precipitated from the solution and recovered before the subsequent
treatment with a tetravalent titanium halide.
Subsequent to halogenation, the product is contacted with a
tetravalent titanium compound such as a dialkoxy-titanium dihalide,
` alkoxy-titanium trihalide, phenoxy-titanium trihalide or titanium
tetrahalide. The most preferred titanium compound is titanium
tetrachloride. This treatment basically serves to increase the content
of tetravalent titanium in the catalyst component. This increase should
preferably be sufficient to achieve a final atomic ratio of tetravalent
titanium to magnesium in the catalyst component of from 0.005 to 3.0,
-~ particularly of from 0.02 to 1Ø To this purpose the contacting with
the tetravalent titanium compound is most suitably carried out at a
` temperature of from 60 to 136 C during 0.1-6 hours, optionally in the
prPsence of an inert hydrocarbon diluent. Particularly preferred
` contacting temperatures are from 70 to 120C and the most preferred
,
contacting periods are in between 0.5 to 2.5 hours.
After the treatment with tetravalent titaniu~ compound the
;~ catalyst component may be isolated from the reaction mediu~ and washed to
remove unreacted titanium compound. The preferred halogen atom contained
in the titanium compound which serves as halogenating agent in the
tetravalent titanium compound with which the halogenated product is
contacted, is chlorine.
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; The organoaluminum compound to be the employed as cocatalyst
may be chosen from any of the known activators in olefin polymerization
catalyst systems comprising a titanium halide. Hence, aluminum trialkyl
compounds, dialkyl aluminum halides and dialkyl aluminum alkoxides may be
successfully used. Aluminum trialkyl compounds are preferred,
particularly those wherein each of the alkyl groups has 2 to 6 carbon
atoms, e.g. aluminum triethyl, aluminum tri-n-propyl, aluminum
tri-isobutyl, aluminum tri-isopropyl and aluminum dibutyl-n-amyl.
One or more electron donors may be included in the catalyst
either independently or along with the organoaluminum compound. This
electron donor is commonly known as a selectivity control agent.
Suitable electron donors, which are used in combination with or reacted
with an organoaluminum compound as selectivity control agents and which
are also used in the preparation of the solid catalyst component are
ethers, esters, ketones, phenols, amines, amides, imines, nitriles,
phosphines, silanes, phosphites, stilbines, arsines, phosphoramides and
; alcoholates. ~xamples of suitable donors are those referred to in U.S.
Patent No. 4,136,243 or its equivalent, British Specification No.
-~ 1,486,194 and in British Specificati J No. 1,554,340 or its equivalent
Gexman Offenlegungsschrift No. 2,729,126. Preferred donors are esters
` and organic silicon compounds. Preferred esters are esters of aromatic
carboxylic acids, such as ethyl and methyl benzoate, p-methoxy ethyl ben-
zoate, p-ethoxy methyl benzoate, p-ethoxy ethyl benzoate. Other esters are
ethyl acrylate,`methyl methacrylate, ethyl acetate, dimethyl carbonate,
~` 25 dimethyl adipate, dihexyl fumarate, dibutyl maleate, ethylisopropyl
oxalate, p-chloro ethyl benzoate, p-amine hexyl benzoate, isopropyl
naphthenate, n-amyl toluate, ethyl cyclohexanoate, propyl pivalate.
Examples of the organic silicon compounds useful herein include alkoxy-
silanes and acyloxysilanes of the general formula R nSi(OR )4 n where n
is between zero and three, R is a hydrocarbon group or a halogen atom
and R2 is a hydrocarbon group. Specific examples include
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trimethylmethoxy silane, triphenylethoxy silane, dimethyldimethoxy
silane, phenyltrimethoxy silane and the like. The donor used as
selectivity control agent in the catalyst may be the same as or different
from the donor used for preparing the titanium containing constituent.
Preferred electron donors for use in preparing the titanium constituent
are ethyl benzoate and isobutyl phthalate. Preferred as selectivity
control agent in the total catalyst is p-ethoxy ethyl benzoate,
phenethyltrimethoxy silane and diphenyldimetho~y silane.
Preferred amounts of electron donor contained in the
cocatalyst, calculated as mol per mol aluminum compounds, are chosen from
; the range of rom 0.1 to 1.0, particularly from 0.2 to 0.5. Preferred
; amounts of electron donor optionally contained in the solid component,
calculated as mol per mol of magnesium are those within the range of from
0.05 to 10, particularly from 0.1 to 5Ø The solid catalyst components
described herein are novel compositions per se and they are also included
within this invention. To prepare the final polymerization catalyst
composition, components are simply combined, most suitably employing a
molar ratio to produce in the final catalyst an atomic ratio of aluminum
to titanium of from 1 to 80, preferably less than 50.
; 20 The present invention is also concerned with a process for
polymerizing an olefin such as ethylene or butylene, preferably
propylene, employing the novel catalyst compositions. These
polymerizations may be carried out by any one of the conventional
. ,
techniques, such as gas phase polymerization or slurry polymerization
using liquid monomer or an inert hydrocarbon diluent as liquid medium.
Hydrogen may be used to control the molecular welght o-f the polymer
1 without detriment to the stereospecific performance of the catalyst
compositions. Polymerization may be effected batchwise or continuously
with constant or intermittent supply of the novel catalyst compositions
or one of the catalyst components to the polymerization reactor. The
activity and stereospecificity of the novel catalyst compositions are so
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pronounced that there is no need for any catalyst removal or
polymer extraction techniques. Total metal residues in the
polymer, i.e. the combined aluminum, chlorine and titanium con-
tent, can be as low as 200 ppm, even less than 100 ppm, as will
be shown in the examples.
Example 1
-
A mixture of linear aldehydes containing 17 milli-
moles acetaldehyde, 17 millimoles butyraldehyde and 16 millimoles
octylaldehyde was mixed in 10 milliliters of chlorobenzene and
then added dropwise to a stirred solution cf 25 millimoles of
dibutyl ma~nesium in 32.8 milliliters of heptane plus 40 milli-
liters of chlorobenzene over a 20 minute period. (The reaction
product was not soluble and had the consistency of very crumbly
jello.) Then 1.8 milliliters of ethylbenzoa~e was added to the
solution and 75 milliliters of an 80/20 mixture of titanium
tetrachloride and chlorobenzene was also ad~ed. The tempera~ure
was raised to 80C and the solution was stirred for 30 minutes.
The precipitated product was filtered and then washed twice with
a 50/50 mixture of titanium tetrachloride and chl~robenzene at
,. . .
20- 80C and then was filtered hot and rinsed wi~h six 150 ml por-
tions of isopentane at room temperature. Finally, the product
was dried under flowing nitrogen at 40C.
-I Example 2
The procedure of Example 1 was repeated except that
the linear aldehydes were replaced by 50 millimoles of 2-ethyl-
`, ;'t hexanal (2-ethylhexaldehyde). The reaction product was a pale
.,
~ yellow solution which had the consistency of wa~er. This illus-
.:
trates that a branched aldehyde creates a soluble magnesium
alkoxide while the linear aldehydes of Example 1 did not. After
adding ethyl benzoate a catalsyt was prepared as described in
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Example 1. The catalyst particles come out in a narrow particle
size range which will carry on to the polymer.
. ~
The procedure of Example 2 was repeated except that
isopentane was used as the solvent in place of chlorobenzene.
Again, the intermediate reaction product was a pale yellow
solution which had the consistency of water. Thus, the advan-
tages of the Present invention Were achieved even though
isopentane, wh;ch is not as good a solyent as chlorobenzene, was
used, whereas the l$near aldehydes o~ Example 1 did not allow
the achievement of the advantages of the present invention.
After halogenation and treatment with TiC14 and ethylbenzoate,
the catalyst particles come out in a narrow particle size range
which will carry on to the polymer.
Exa~ple 4
The procedure of Example 1 was repeated except that
the 16 millimoles of octylaldehyde were replaced by 16 millimoles
l
of 2-ethylhexanal. The product was a pale yellow solution which
had the consistency of water. This example illustrates that a
mixture of aldehydes having a minor amount of the branched
~ aldehyde can still be used to achieve the advantages of the
; present invention. After halogenation and treatment with TiC14
I and ethylbenzoate, the catalyst particles come out in a narrow
particle size range which will carry on to the polymer.
Example 5
;
-;' Fifty millimoles of paraformaldehyde (and 60 milli-
'j liters of chlorobenzene) were stirred overnight wi~h 25 milli-
moles of a mixed alkyl magnesium solution (available from Ethyl
Corporation containing alkyls from C4 to C20 with the peak in
the C4 to C8 range~. Then 1.8 milliliters of ethylbenzoate was
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added to the non-viscous solution and 75 milliliters of an 80/20
mixture of titanium tetrachloride and chlorobenzene was also
added. The temperature was raised to 80C and the solution was
stirred for 30 minutes. The precipitated product was filtered
and then washed twice with a 50/50 mixture of titanium tetra-
chloride and chlorobenzene at 80C and then was filtered hot
and rinsed with six 150 ml por~ions of isopentane at room
temperature. ~inally, the product was dried under flowing
nitrogen at 40C. The catalyst contained 4.08% titanium and
17.43% magnesium. The catalyst particles came out in a narrow
particle size range which carried on to the polymerO
Example 6
The catalyst prepared above was used to polymerize
propylene in a li~uid pool polymerization (LIPP) process which
was carried out for 1 hour at 67C, in a 1 gallon autoclave,
using 2.7 liters of propylene, 132 millimoles of hydrogen and
,
sufficient catalyst to provide 8 micromoles of titanium. Tri-
ethyl aluminum (70 mols per mole of titanium) was mixed with
17.5 millimoles of the selectivity control agent, ethylbenzoate,
and premixed with the procatalyst made in Example 5 for 5 to 30
minutes before injection or in~ected directly into the autoclave
before procatalyst injection. The producti~ity of the catalyst
.,
from Example 5 was 160 kg of propylene per gram of titanium and
the xylene solubles were 8%.
Example 7
The procedure of Example 5 was repeated using
.,
butyraldehyde instead of paraformaldehyde. The catalyst contain-
ed 2.04% titanium and 17.36% magnesium. The catalyst particles
came out in a narrow particle size range which carried on to
the polymer.
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Example 8
The catalyst prepared in Example 7 wasused to poly-
merize propylene in accordance with the procedure of Example 6.
The productivity of the catalyst of Example 7 was 500 kg of
polypropylene per gram of titanium at a xylene solubles of
3.7%.
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