Olefin polymerization catalysts from soluble magnesium alkoxides made from mixed magnesium alkyls and aryls

A process for polymerizing alpha olefins with a polymerization catalyst containing a solid catalyst component which is prepared by mixing two or more alkyl or aryl magnesium compounds with an aldehyde or a ketone in the presence of a solvent, adding a tetravalent titanium halide to the solution, recovering the resulting precipitate, and contacting the precipitate with a tetravalent titanium halide.

BACKGROUND OF THE INVENTION 
The present invention relates to olefin polymerization catalyst 
compositions comprising a magnesium halide and a titanium halide and to a 
process for the polymerization of olefins using 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 polymerization activity and the stereospecific performance 
of such compositions may be improved by incorporating an electron donor 
(Lewis base) into the component comprising titanium, into the 
organoaluminum 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. 
The manufacture of magnesium halide supported catalysts for the 
polymerization of olefins by halogenating a magnesium alkoxide is well 
known. See U.S. Pat. Nos. 4,400,302 and 4,414,132 to Goodall et al. Since 
the 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. 
The present invention provides a simplified means for morphology control 
for magnesium alkoxide catalyst particles. The magnesium alkoxide is 
simply formed in solution from a chemical reaction between a mixture of 
two or more alkyl or aryl magnesium compounds and any aldehyde or ketone. 
The use of mixed magnesium alkyls or aryls forms a mixture of magnesium 
alkoxides which is extremely soluble in organic solvents because of 
entropic effects. Others have prepared soluble magnesium alkoxide catalyst 
components by forming a complex of the magnesium alkoxide and a compound 
of another metal, such as aluminum, zinc or boron. U.S. Pat. Nos. 
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 INVENTION 
The present invention relates to a solid catalyst component consisting of 
particles with a narrow particle size distribution which is prepared by 
mixing two or more alkyl or aryl magnesium compounds with an aldehyde or 
ketone in the presence of a solvent, adding a tetravalent titanium halide 
to the solution, recovering the resulting precipitate, and then contacting 
the precipitate with a tetravalent titanium halide. An electron donor 
and/or a halohydrocarbon may also be added to the solution along with the 
tetravalent 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 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 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 
effects which encourage the solubility of the magnesium alkoxide product. 
Preferred magnesium compounds are selected from dialkyl and diaryl 
magnesium 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, isobutylpropyl magnesium, octylisoamyl magnesium, ethylheptyl 
magnesium, naphthylphenyl magnesium, cumylphenyl magnesium, diphenyl 
magnesium, ethylphenyl magnesium and isobutylnaphthyl magnesium. 
As discussed above, there must be two or more alkyl and aryl magnesium 
compounds present in the solution in order to obtain the proper entropic 
effects for good solubility of the alkoxides formed in the solution. Any 
of the above-described alkyl or aryl magnesium compounds may be mixed 
together and used to form the solid catalyst component of the present 
invention. Preferred mixtures include n-butyl-isobutyl magnesium and 
dialkyl magnesium containing alkyls from C.sub.2 to C.sub.20 (with the 
peak at C.sub.4 to C.sub.8). 
As stated above, the aldehydes or ketones must be included in the solution 
in order to form the magnesium alkoxides. Specific examples of aldehydes 
for use in this invention are paraformaldehyde, acetaldehyde, 
propionaldehyde, butyraldehyde and valeraldehyde. Specific examples of 
such ketones include acetone and 2-butanone. 
The solvent used for the solution of the mixed magnesium alkyl or aryl 
compounds and the aldehyde or ketone is generally any nonreactive solvent 
which will form a homogenous solution of the three and which will also 
dissolve or at least disperse or suspend the tetravalent titanium halide. 
The preferred solvents for use herein are isopentane, isooctane, heptane, 
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 1.0. 
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 tetravalent titaniums are aryloxy- or alkoxydi- and 
-trihalides, such as dihexanoxytitanium dichloride, diethoxytitanium 
dibromide, isopropoxytitanium triiodide, phenoxytitanium trichloride, 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 12, 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, di-chloro-fluoroethane, trichloropropane, 
dichlorodibromodifluorodecane, 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 filtration, 
decantation or another suitable method and subsequently washed with an 
inert hydrocarbon diluent, 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 magnesium 
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 tetrvalent 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 1.0. 
To this purpose the contacting with the tetravalent titanium compound is 
most suitably carried out at a temperature of from 60.degree. to 
136.degree. C. during 0.1-6 hours, optionally in the presence of an inert 
hydrocarbon diluent. Particularly preferred contacting temperatures are 
from 70.degree. to 120.degree. C. and the most preferred contacting 
periods are in between 0.5 to 2.5 hours. 
After the treatment with tetravalent titanium compound the catalyst 
component may be isolated from the reaction medium 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. 
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 triisopropyl 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. 
Examples of suitable donors are those referred to in U.S. Pat. No. 
4,136,243 or its equivalent British Specification No. 1,486,194 and in 
British Specification No. 1,554,340 or its equivalent German 
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 benzoate, 
p-ethoxy methyl benzoate, p-ethoxy ethyl benzoate. Other esters are ethyl 
acrylate, methyl methacrylate, ethyl acetate, dimethyl carbonate, 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 alkoxysilanes and 
acyloxysilanes of the general formula R.sup.1.sub.n Si(OR.sup.2).sub.4-n 
where n is between zero and three, R.sup.1 is a hydrocarbon group or a 
halogen atom and R.sup.2 is a hydrocarbon group. Specific examples include 
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 in p-ethoxy ethyl benzoate, phenethyltrimethoxy silane 
and diphenyldimethoxy silane. 
Preferred amounts of electron donor contained in the cocatalyst, calculated 
as mol per mol aluminum compounds, are chosen from the range of from 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 5.0. 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. 
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 
weight of the polymer 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 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 content, can be 
as low as 200 ppm, even less than 100 ppm, as will be shown in the 
examples. 
EXAMPLE 1 
Fifty millimols of paraformaldehyde and 60 milliliters of chlorobenzene 
were stirred overnight with 25 millimols of a mixed alkyl magnesium 
solution (available from Ethyl Corporation containing alkyls from C.sub.4 
to C.sub.20 with the peak in the C.sub.4 to C.sub.8 range). Then 1.8 
milliliters of ethylbenzoate was 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 80.degree. C. 
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 chlorobenzene at 80.degree. C. and then was filtered hot 
and rinsed with six 150 ml portions of isopentane at room temperature. 
Finally, the product was dried under flowing nitrogen at 40.degree. C. 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 
polymer. 
EXAMPLE 2 
The catalyst prepared above was used to polymerize propylene in a liquid 
pool polymerization (LIPP) process which was carried out for 1 hour at 
67.degree. C., in a 1 gallon autoclave, using 2.7 liters of propylene, 132 
millimoles of hydrogen and sufficient catalyst to provide 8 micromoles of 
titanium. Triethyl 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 1 for 5 to 30 minutes before 
injection or injected directly into the autoclave before procatalyst 
injection. The productivity of the catalyst from Example 1 was 160 kg of 
propylene per gram of titanium and the xylene solubles were 8%. 
EXAMPLE 3 
The procedure of Example 1 was repeated using butyraldehyde instead of 
paraformaldehyde. The catalyst contained 2.04% titanium and 17.36% 
magnesium. The catalyst particles came out in a narrow particle size range 
which carried on to the polymer. 
EXAMPLE 4 
The catalyst prepared in Example 3 was used to polymerize propylene in 
accordance with the procedure of Example 2. The productivity of the 
catalyst of Example 3 was 500 kg of polypropylene per gram of titanium at 
a xylene solubles of 3.7%.