CA1328101C - Olefin polymerization catalysts from soluble magnesium alkoxides made from magnesium alkyls and aryls - Google Patents

Abstract

ABSTRACT
A solid catalyst component which is prepared by:
mixing an alkyl or aryl magnesium compound with a branched or aromatic aldehyde in the presence of a solvent or 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 pre-cipitate; and contacting the precipitate with a tetravalent titanium halide.

Description

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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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- 2 - 61~15-3241 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 ~' _ 3 _ ~ 3 2 ~ ~ ~6~815-3241 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-- ~L 3 ~
- 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 1328~

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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- 9 - 61815-32~1 Example 1. The catalyst particles come out in a narrow particle size range which will carry on to the polymer.

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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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~ 61815-3241 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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Claims (16)

1. A process for preparing a catalyst component which is useful in the polymerization of alpha olefins, contains no inert support material and has a narrow particle size distri-bution, which comprises:
1) a) mixing an alkyl or aryl magnesium compound with a branched or aromatic aldehyde in the presence of a solvent or b) mixing two or more alkyl or aryl magnesium com-pounds with an aldehyde or ketone in the presence of a solvent;

2) adding a tetravalent titanium halide to a solution resulting from step 1);

3) recovering a precipitate from step 2); and

4) contacting the precipitate with a tetravalent titan-ium halide.

2. A process for preparing a catalyst composition which is useful in the polymerization of alpha olefins, contains no inert support material and has a narrow particle size distri-bution, which comprises:
1) mixing an alkyl or aryl magnesium compound with a branched or aromatic aldehyde in the presence of a solvent;
2) adding a tetravalent titanium halide to the solution;
3) recovering the resulting precipitate; and 4) contacting the precipitate with a tetravalent titanium halide.

3. A process for preparing a catalyst component which is useful in the polymerization of alpha olefins, contains no inert support material and has a narrow particle size distri-bution, which comprises:
1) mixing two or more alkyl or aryl magnesium compounds with an aldehyde or ketone in the presence of a solvent;
2) adding a tetravalent titanium halide to the solution;
3) recovering the resulting precipitate; and 4) contacting the precipitate with a tetravalent titanium halide.

4. The process of claim 1, 2 or 3 wherein the magnesium compound is selected from the group consisting of diethyl mag-nesium, dibutyl magnesium, di-n.amyl magnesium, dicyclohexyl magnesium, di-isopropyl magnesium, isobutylpropyl magnesium, octylisoamyl magnesium, ethylheptyl magnesium, naphthylphenyl magnesium, cumylphenyl magnesium, diphenyl magnesium, ethyl-phenyl magnesium and isobutylnaphthyl magnesium.

5. The process of claim 1 step 1)b) or claim 3 wherein the magnesium compounds are selected from the group consisting of diethyl magnesium, dibutyl magnesium, di-n.amyl magnesium, dicyclohexyl magnesium, di-isopropyl magnesium, isobutylpropyl magnesium, octylisoamyl magnesium, ethylheptyl magnesium, naphthylphenyl magnesium, cumylphenyl magnesium, diphenyl magnesium, ethylphenyl magnesium and isobutylnaphthyl magnesium and a mixture of n-butyl-isobutyl magnesium and dialkyl magnes-ium containing alkyls from C2 to C20 (with peak at C4 to C8).

6. The process of claim 1 or 2 wherein a linear alde-hyde is added to the solution of claim 1 step 1)a) or claim 2 step 1).

7. The process of claim 1 or 2 wherein a linear alde-hyde is added to the solution of claim 1 step 1)a) or claim 2 step 1) said linear aldehyde being selected from the group con-sisting of paraformaldehyde, acetaldehyde, propionaldehyde, butyraldehyde and valeraldehyde.

8. The process of claim 1 step 1)a) or claim 2 wherein a branched aldehyde is present and is 2-ethylhexanal.

9. The process of claim 1 step 1)a) or claim 2 wherein an aromatic aldehyde is present and is benzaldehyde.

10. The process of claim 1 step 1)b) or claim 3 wherein an aldehyde is present and it is selected from the group con-sisting of paraformaldehyde, acetaldehyde, propionaldehyde, butyraldehyde and valeraldehyde.

11. The process of claim 1 step 1)b) or claim 3 wherein a ketone is present and it is selected from the group consisting of acetone and 2-butanone.

12. The process of claim 1, 2 or 3 wherein the tetra-valent titanium halide is titanium tetrachloride.

13. The process of claim 1, 2 or 3 wherein an electron donor is added to the solution in step 2).

14. The process of claim 1, 2 or 3 wherein ethyl benzo-ate is added as an electron donor to the solution in step 2).

15. The process of claim 1, 2 or 3 wherein a halohydro-carbon is added to the solution of step 2).

16. The process of claim 1, 2 or 3 wherein chlorobenzene is added to the solution of step 2).