CA1227785A - Olefin polymerization catalyst compositions and polymerization process - Google Patents

Abstract

A B S T R A C T

OLEFIN POLYMERIZATION CATALYST COMPOSITIONS
AND POLYMERIZATION PROCESS

A highly active and stereoselective olefin polymerization catalyst component is obtained by halogenating a magnesium compound of the formula MgRIR'' wherein R' is an alkoxide or aryloxide group and R" is an alkoxide or aryloxide group or halogen, with a halide of tetravalent titanium in the presence of a halohydrocabon, and contacting the halogenated product with an acid halide and a tetravalent titanium compound.

Description

12Z'7~7~15 K 45~8 CAN

OLEFIN POLYMERIZATION CATALYST COMPOSITIONS
AND POLYMERIZATION PROCESS

This invention relates to olefin polymerization catalyst components comprising a magnesium halide and a titanium halide and to a process for the polymerization of olefins using such catalyst components.
Numerous proposals are known from the prior art to provide olefin polymerization catalysts by combining a solid component comprising magnesium, titanium and chlorine with an activating organoaluminium compound. These may be referred to as supported coordination catalysts or catalyst systems. The activity and stereo specific performance of such compositions is generally improved by incorporating an electron donor (Lewis base) in the solid component and by employing as a third catalyst component an electron donor which may be complexes in whole or in part with the activating organoaluminium compound.
For convenience of reference, the solid titanium-containing constituent of such catalysts is referred to herein as "pro-catalyst", the organoaluminium compound, whether used separately or partially or totally complexes with an electron donor, as "cocatalyst", and the electron donor compound, whether used separately or partially or totally complexes with the organ-aluminum compound, as "selectivity control agent" (SPA).
The catalyst systems of this type which have been disclosed in the prior art generally are able to produce olefin polymers in high yield and, in the case of catalysts for polymerization of propylene or higher alpha-olefins, with high selectivity to stereo regular polymer. However, further improvements in pro-ductility at high stereo regularity are still being sought.

~ZZ77~5 The objective of workers in this art is to provide catalyst systems which exhibit sufficiently high activity expressed in terms of kg polymer produced per g To (kg polliwog To), to permit the production of polyolefins in such high yield as to obviate the necessity of extracting residual catalyst components in a dashing step. In the case of propylene and higher olefins, an equally important objective is to provide catalyst systems of sufficiently high selectivity toward isotactic or otherwise stereo regular products to obviate the necessity of extracting tactic polymer components.
Suitable pro catalysts have been disclosed which comprise Ida. a composition prepared by halogenating a magnesium compound MgR'R" (wherein R' and R" are alkyd, aureole, alkoxide.
or aryloxide groups and R" may also be a halogen) by reaction with a halide of tetravalent titanium in the presence of an electron donor and a halo hydrocarbon followed by contact of the halogenated product with a tetravalent titanium compound.

This invention provides still further improvements of the catalysts and processes of the prior art. Catalysts which comprise the solid titanium-containing catalyst constituents of this invention in combination with an organoaluminium cocatalyst and a selectivity control agent or with an at least partial reaction product of an organoaluminium compound and a selectivity control agent are capable of producing polypropylene of commercially desired isotacticity at very high activity.
This invention provides a process for producing an improved olefin polymerization catalyst component. which comprises:
a) halogenating a magnesium compound of the formula MgR'R"
where R' is an alkoxide or aryloxide group an R" is an alkoxide or aryloxide group or halogen, with a tetravalent titanium halide in the presence of a halo hydrocarbon and an electron donor, therein forming a halogenated product; this halogenated product being subjected to a contacting treat-mint selected from A

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b) 1. contacting an acid halide of the formula A C - X

where A is an alkyd, aureole, substituted alkyd, or substituted aureole group and X is a halide at a temperature of about 40 to about 140 C; followed by contacting the resulting acid halide-treated product with a tetravalent titanium halide at a temperature of from 40 to 140 C, and

2. contacting with a mixture of the alone said acid halide and a tetravalent titanium halide at a temperature of from 40 to 140 C.
The first step in preparing the pro catalysts of the present invention comprises halogenating a magnesium compound of the formula MgR'R" where R' is an alkoxide or aryloxide group an R"
is an alkoxide or aryloxide group or halogen, with a tetravalent titanium halide in the presence of a halo hydrocarbon and an electron donor, therein forming a halogenated product.
Examples of halogen containing magnesium compounds that can be used as starting materials for the halogenating reaction are alkoxy and airlocks magnesium halides, such as isobutoxy magnesium chloride, ethics magnesium bromide, phonics magnesium iodide, cumyloxy magnesium bromide and naphtenoxy magnesium chloride.
Preferred magnesium compounds to be halogenated are selected from magnesium dialkoxides and magnesium diaryloxides.
In such compounds the alkoxide groups suitable have from 1 to 8 carbon atoms, and preferably from 2 to 8 carbon atoms. Examples of these preferred groups of compounds are magnesium dyes-prop oxide, magnesium diethoxide, magnesium dibutoxide, magnesium diphenoxide, magnesium dinaphtenoxide and ethics magnesium isobutoxide. Magnesium diethoxide is particularly preferred.

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Magnesium compounds comprising one alkyd group and one alkoxide or aryloxide group also be employed, as well as come pounds comprising one aureole group and one alkoxide or aryloxide group. Examples of such compounds are phenol magnesium phenol wide, ethyl magnesium but oxide, ethyl magnesium phenoxide andnaphthyl magnesium isoamyloxide.
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 it 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 magnesium is at least 1.5. The most preferred reactions are those leading to fully halogenated reaction products. Such halogenation reactions are suitably effected by employing a molar ratio of magnesium compound to titanium compound of 0.005:1 to 2:1, preferably 0.01:1 to 1:1. These halogenation reactions are conducted in the additional presence of an halo hydrocarbon and an electron donor.
An inert hydrocarbon delineate or solvent may also be present.
When using an inert delineate or solvent, this should of course not be used as a complete substitute for the halo hydrocarbon.
Suitable halides of tetravalent titanium include airlocks-or alkoxy-di- and -trihalides, such as dihexanoxy-tltanium dichlorides diethoxy-titanium dibromide, isopropoxy-titanium treaded and phenoxy-titanium trichloride; titanium twitter-halides are preferred; most preferred is titanium tetrachloride.
Suitable halo hydrocarbons are compounds such as bottle chloride, Amy chloride and the following more preferred come pounds. Preferred aliphatic halo hydrocarbons are halogen-substituted hydrocarbons with 1 to 12, particularly less than Caribbean atoms per molecule, comprising at least two halogen atoms, such as dibromomethane, trichloromethane, 1,2-dichloro-ethanes dichlorobutane, 1,1,3-trichloroethane, trichlorocyclo-hexane, dichlorofluoroethane, trichloropropane, trichloro-Z2~8S

fluorooctane, dibromodifluorodecane, he~achloroethane andtetrachloroisooctane. Carbon tetrachloride and l,l,3-tri-chloroethane are preferred aliphatic halo hydrocarbons. Aromatic halo hydrocarbons may also be employed, e.g., chlorobenzene, bromobenzene, dichlorobenzene, dichlorodibromobenzene, naphthyl chloride, chlorotoluene, dichlorotoluenes, and the like; sheller-Bunsen ant dichlorobenzene are preferred aromatic holder-carbons. Chlorobenzene is the most preferred halo hydrocarbon.
The halogenation normally proceeds under formation of a solid reaction product which may be isolated from the liquid reaction medium by filtration, recantation or another suitable method and may be subsequently washed with an inert hydrocarbon delineate, such as Nixon, iso-octane or Tulane, to remove any unrequited material, including physically absorbed holder-carbon.
The novel and unobvious aspect of the present invention comprises treating the above halogenated product with a particular acid halide prior to or concurrent with treatment with a tetravalent titanium halide.
Acid halides employed herein have the formula C X

where A is an alkyd, aureole, substituted alkyd or substituted aureole group and X is a halide. Preferably, A is a phenol group and X
is chloride. Accordingly, the preferred acid halide is bouncily chloride.
The acid halide treatment results in significantly improved selectivity or equivalently a significant increase in polymeric ration activity, measured as kg polliwog Tip over the activity of untreated catalyst at the same selectivity. The amount of acid halide employed is 50 to 200 Molly per mole of My and preferably 12~

less than the total equivalent amount of residual alkoxide contained in the halogenated magnesium compound. Suitably, the treatment is carried out at a temperature of 40 to 140 C during 0.1 to 4 hours. Particularly preferred contacting temperatures are from 60 to 110 C and the most preferred contacting periods are 0.3 to 1 hour.
The product is also contacted with a tetravalent titanium compound such as a dialkoxy-titanium dwelled, alkoxy-titanium troweled, phenoxy-titanium troweled or titanium tetrahalide, either simultaneously with or subsequent to the contacting with acid halide. The most preferred titanium compounds are titanium tetrahalides and especially titanium tetrachloride. This treat-mint increases the content of titanium tetrachloride in the solid catalyst component. This increase should preferably be sufficient to achieve a final atomic ratio of tetravalent titanium to magnesium in the solid 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 I
during 0.1-6 hours, optionally in the presence of an inert hydrocarbon delineate. Particularly preferred contacting temperatures are from 70 to 120 C and the most preferred contacting periods are in between 0.5 to 3.5 hours.
At the end the catalyst component is suitably isolated from the liquid reaction medium and washed to remove unrequited titanium compound. The titanium content of the final, washed catalyst constituent it suitably between about 1.5 to 3.6 percent by weight or up to about 4.5 percent.
The preferred halogen atom, possibly contained in the

3 magnesium compound to be halogenated, and contained in the titanium compound which serves as halogenating agent and in the tetravalent titanium compound with which the halogenated product is contacted, is chlorine.

12;~7~5 Suitable electron donors, which are used in combination with or reacted with an organoaluminium compound as selectivity control agents and which are also used in the preparation of the solid catalyst component are ethers, esters, kittens, phenols, amine, asides, mines, nitrites, phosphines, phosphates, stubbiness, arsines, phosphoramides and alcoholates. Examples of suitable donors are those referred to in US. Patent 4J136,243 or its equivalent British Specification 1,486,194 and in British Specification 1,554,340 or its equivalent German Offenlegungs-shrift 2,729,126. Preferred donors are esters and dominoes, particularly esters of aromatic carboxylic acids, such as ethyl and methyl bonniest, p-methoxy ethyl bonniest, p-ethoxy ethyl bonniest, ethyl acrylate, methyl methacrylate, ethyl acetate, dim ethyl carbonate, dim ethyl adipate, dihexyl fumarate, dibutyl Malta, ethyl isopropyl oxalate, p-chloro ethyl bonniest, p-amino Huxley bonniest, isopropyl naphtenate, namely twilight, ethyl cyclohexanoate, propel pivalate, N,N,N',N'-tetramethyl-ethylene Damon, 1,2,4-trimethyl piperazine, twitter-methyl plperidine and similar compounds. 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 bonniest and p-methyl twilight. Preferred as selectivity control agent in the total catalyst are p-methoxy ethyl bonniest and p-ethoxyethyl-bonniest.
The organoaluminium compound to be employed as cocatalyst may be chosen from any of the known activators in olefin polyp merization catalyst systems comprising a titanium halide but is most suitably free of halogens. While aluminum trialkyl come pounds, dialkylaluminium halides and dialkylaluminium alkoxides may be used, aluminiumtrialkyl compounds are preferred, particularly those wherein each of the alkyd groups has 2 to 6 carbon atoms, e.g., aluminiumtriethyl, aluminiumtri-n-propyl, -~2Z77~35 aluminiumtri-isobutyl, aluminiumtri-isopropyl and aluminum-dibutyl-n-amyl.
Preferred proportions of selectivity control agent, employed separately, in combination with, or reacted with an organoaluminium compound, calculated as mow per mow aluminum compound, are in the range from 0.1 to 1.5, particularly from 0.2 to 0.5.
Proportions of electron donor contained in the solid catalyst component, calculated as mow per mow of magnesium, are suitably in the range of from 0.01 to 10, e.g., from 0.05 to 10 and from 0.1 to 5.0 and especially from 0.8 to 2.2.
To prepare the final polymerization catalyst composition, pro catalyst, cocatalyst and selectivity control agent, if used separately, may be 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 150, and suitably from about 10 to about 150. The catalysts of this invention tend to exhibit very good activity at much lower Alto ratios, e.g., below 80:1 and even below 50:1, than prior art catalysts of the same type.
It may, however, be advantageous under some conditions to employ them at higher Alto ratios. In general, Alto ratios in the range of 30:1 to 100:1 and especially of about 50:1 to 80:1 will be found advantageous.
Improved pro catalysts prepared according to this invention are useful in the same types of polymerization of alpha-mono-olefins in which the unimproved pro catalysts are useful. The catalysts may be employed in the polymerization or Capella-merization of alpha-monoolefins of 2 to 8 carbon atoms per molecule, conducted at conditions known for the polymerization of the respective olefins when using McCoy supported keyword-nation catalysts.
Polymerization of propylene as sole olefin feed or in combination with small amounts, e.g., from l to 20 mole percent, of ethylene, button or other alpha olefin comonomer, may be conducted with the catalysts of the invention, in a liquid 31 ~Z~5 g system with an inert delineate such as a paraffinic liquid of 3 to 15 carbon atoms per molecule, or in a liquid system containing propylene as sole delineate or together with a small amount of propane, or in vapor phase. Propylene polymerization in liquid phase is conducted at temperatures of 50 to 80 C and at a pressure sufficient to maintain liquid conditions.
In propylene polymerization, the reaction mixture is typically maintained at conditions at which the polymer is produced as a slurry of powder in the reaction mixture. The catalyst systems of this invention are extremely active and highly stereo selective in propylene polymerization, so that no removal of catalyst components or of tactic polymer from the polymer product is required.
Olefin polymerization may also be conducted as a solution process in which the polymer is produced as a solution in monomer or delineate. Such a process is preferred in the polyp merization of button as described, for example, in US. Patent 3,362,940.
The polymerization activity of the pro catalyst is determined as kg polymer/g To in a standard one hour batch reaction The selectivity to isotactic polypropylene is determined by measuring the amount of zillion soluble polymer (US), in accordance with regulations of the US. Food and Drug Administration. The US test is carried out as follows:
The sample is completely dissolved in zillion in a stirred flask by heating under reflex at 120 C. The flask is then immersed in a water bath at 25 C without stirring for one hour, during which the insoluble portion precipitates. The precipitate is 3 filtered off and the solubles present in the filtrate are determined by evaporating a 20 ml Alcott of the filtrate, drying the residue under vacuum, and weighting the residue. The xylene-solubles consist of amorphous material with some low molecular weight crystalline material. (FDA regulations 121.2501 and 121.2510, 1971.) sty The following examples illustrate the invention:
Examples 1-5 1. Magnesium ethoxide (5.72 g, 50 Molly) was stirred at room temperature with ethyl bonniest (2.4 ml, 16.7 Molly) and 75 ml of chlorobenzene as titanium tetrachloride (75 ml, 680 Molly) was added over the course of 10 min. The mixture was brought to 110 C and stirred for 60 min. then filtered hot. The resulting solid ("S") was slurries in chlorobenzene (60 ml) containing bouncily chloride (0.31 ml, 2.7 Molly) and held at 110 C for 20 mix then filtered hot. The resulting solid was washed for 10 minutes each with two 60 ml portions of Tokyo at 110 C and filtered hot. The resulting solid was washed at room temperature with six 150 ml portions of isopentane then dried under moving nitrogen at 40 C. Yield 5.77 g of pro catalyst "A".
2. Pro catalyst "B" was prepared by essentially the same procedure except that the bouncily chloride treatment was carried out for 60 min. at 110 C and that the two succeeding 110 C
TlC14 washes were with only 40 ml of titanium tetrachloride.
Yield 6.5 g.
3. Magnesium ethoxide (5.72 g, 50 Molly) was stirred at room temperature with bouncily chloride ~1.8 ml, 15.6 Molly) and 75 ml of chlorobenzene as titanium tetrachloride (75 ml, 680 Molly) was added over the course of 10 min. The mixture was brought to 100 C and stirred for 180 min. when filtered hot. The resulting solid was slurries in 40 ml of chlorobenzene and held at 100 C for 120 min. then filtered hot. The resulting solid was slurries in titanium tetrachloride (40 ml) containing bouncily chloride (0.6 ml, 5.2 Molly) and held at 100 C for 120 min. then filtered hot. The resulting solid was washed at room temperature with seven 150 my portions of isopentane then dried under moving nitrogen at 40 C for 100 min. Yield 5.82 g of pro catalyst "C".

4. Solid "S", as prepared in example 1, was slurries in 40 ml of titanium tetrachloride and held at 110 C for 60 mix then ~2Z~785 filtered hot. The resulting solid was slurries in 40 ml of titanium tetrachloride containing bouncily chloride (0.4 ml, 3.5 Molly) and held at 110 C for 60 mix then filtered hot. The resulting solid was washed, at room temperature, with six 150 ml portions of isopentane then dried under moving nitrogen at 40 C. Yield 6.2 g of pro catalyst "D".

5. (Control) Solid "S", as prepared in example l, was treated three times with 40 ml of Tickle held at 110 C for lo mix each and filtered hot. The resulting solid was washed, at room temperature, with six 150 ml portions of isopentane then dried under moving nitrogen at 40 C for 100 mix Yield 6.32 g of pro catalyst "E".
All pro catalysts were subjected to a one-hour standard propylene polymerization-test, which was conducted as follows:
About 1400 g of liquid propylene and 132 Molly of hydrogen in a one gallon (about 4 liter) autoclave equipped with an agitator, was heated to 60 C under sufficient pressure to maintain it in liquid phase. A predetermined amount (Oily Molly) of p-ethyl ethylbenzoate and 2.5 ml (0.7 Molly) of triethyl aluminum as a 5% wit solution in C7-C8 paraffin delineate were then succeccively added to the propylene. To the agitated mixture there was added a sufficient amount of the slurry of pro catalyst in mineral oil to provide 0.01 mealtimes of titanium.
The mixture was agitated and maintained at 67 C.
The pressure was then released and powdered polypropylene recovered.
For the five examples listed in Table 2 (examples 6-10) the zillion solubles were analyzed to be from 3.8 to 4.8%. For convenience of comparison the measured polymerization activities were corrected to equivalent productivities at 4% zillion solubles.

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Activity ProcatalystKg polliwog To Eye (control) .

.

Claims (8)

C L A I M S

1. A process for producing an improved olefin polymerization catalyst component, which comprises:
a) halogenating a magnesium compound of the formula MgR'R"
where R' is an alkoxide or aryloxide group an R" is an alkoxide or aryloxide group or halogen, with a tetravalent titanium halide in the presence of a halohydrocarbon and an electron donor, therein forming a halogenated product; this halogenated product being subjected to a contacting treat-ment selected from b) 1. contacting an acid halide of the formula where A is an alkyl, aryl, substituted alkyl, or substituted aryl group and X is a halide at a temperature of about 40 to about 140 °C; followed by contacting the resulting acid halide-treated product with a tetravalent titanium halide at a temperature of from 40 to 140 °C, and 2. contacting with a mixture of the afore said acid halide and a tetravalent titanium halide at a temperature of from 40 to 140 °C.

2. The method of claim 1 wherein said magnesium compound is a magnesium dialkoxide.

3. The method of claim 1 wherein said halohydrocarbon is a chlorohydrocarbon,

4. The method of claim 1 wherein said acid halide is an acid chloride.

5. The method of claim 1 wherein said electron donor is an aromatic ester.

6. The method of claim 1 wherein said magnesium compound is magnesium diethoxide, said halohydrocarbon is chlorobenzene, said titanium halide is titanium tetrachloride, said electron donor is ethylbenzoate, and said acid chloride is benzoyl chloride.

7. An olefin polymerization catalyst composition comprising an organoaluminium compound, an electron donor, and the solid component produced with the process as claimed in claim 1, in which the atomic ratio of aluminium to titanium is from 1:1 to 150:1.

8. A process for the catalytic polymerization of an olefin which comprises contacting the olefin with an olefin polymerization catalyst composition as defined in claim 7.