WO1988005056A1

WO1988005056A1 - CATALYST COMPONENT FOR ZIEGLER-NATTA CATALYSTS AND METHOD FOR POLYMERIZING alpha-OLEFINS

Info

Publication number: WO1988005056A1
Application number: PCT/FI1987/000167
Authority: WO
Inventors: Luciano Luciani; Barbro LÖFGREN
Original assignee: Neste Oy
Priority date: 1986-12-31
Filing date: 1987-12-10
Publication date: 1988-07-14
Also published as: FR2609035A1; FI76354C; FI865361A0; IT1224643B; FI76354B; BE1000160A7; JPS63175008A; IT8722761A0

Abstract

A catalyst component for use in unsupported Ziegler-Natta catalyst compositions for the polymerization of $g(a)-olefins having at least 3 carbon atoms. The catalyst component is obtained by treating an organomagnesium compound without chlorine with solid silane compounds containing one or two hydroxyl groups and then with titanium halide compounds. The treatment of organomagnesium compound is carried out by first treating with the solid silane compound in a temperature of 60-110C and thereafter with titanium halide compound optionally together with an electron donor compound. An unsupported catalyst composition, which comprises the above mentioned catalyst component together with a cocatalyst and optionally an external donor compound and a process for polymerization of $g(a)-olefins containing at least 3 carbon atoms with the use of the catalyst component are also claimed.

Description

Catalyst component for Ziegler-Natta catalysts and method for polymerizing α-olefins

This invention relates to active catalyst components useful for the Ziegler-Natta catalyst family able to polymerize α-olefins containing at least 3 carbon atoms. This invention relates also a method for preparing active catalyst components for polymerizing α-olefins containing at least 3 carbon atoms. In another aspect this invention relates also to a polymerization process using active catalyst components according to the invention.

When polymerizing olefins using so called Ziegler-Natta catalyst system transition metal compounds are used as essential catalyst components. The preparation of these catalyst components of the last generation typically consists of reacting a metal halide such as magnesium dichloride or an adduct of magnesium dichloride and two to three moles of alcohol with titanium halide compound such as titanium tetrachloride in the presence of Lewis bases as an electron donor compound.

This invention concerns catalyst components, which are prepared from organic magnesium compounds containing no chlorine, a silane compound without chlorine and a titanium halide compound.

In the prior art there are descriptions of catalysts obtained by treating magnesium alkyls with silanol or silane c ompounds and with transition metal compounds in different conditions. For instance, according to US-patent 4525557 ethylene can be polymerized using a catalyst system cont aining a transition metal componentswhich is prepared in three phases: first a Mg-dialkyl compoundsis reacted with a silanol compound and then the reaction product is treated with a trichlorosilane and the final product is treated with a titanium halide. However this catalyst has been used only for polymerizing ethylene and the reaction with a silane compound and magnesium compound has been carried out at room temperature. The catalysts described in this patent are not suitable for polymerizing propylene or other α-olefins.

In US-patent 4335016 a catalyst component for polymerizing ethylene is prepared by reacting first a porous support material such as silica with an alkyl magnesium compoundsand then the product obtained with hydrocarbyloxyhydrocarbylsilane. The catalyst described in this patent is not suitable for polymerizing propylene.

In European patent application 104374 a catalyst component is prepared by reacting an aryl silanol with a halogenated transition metal compound such as titanium tetrachloride and after that reacting the product obtained with an organomagnesium compound. This catalyst componenthas been deposited on a particular carrier and it has been used only for polymerizing ethylene.

We have new found that the catalyst components prepared according to EP 104374 do not give active Ziegler-Natta catalyst compositions when used for the polymerization of propylene. The reason to it was found to be in the order of preparation steps and the reaction conditions. In the claim 1 of said EP-publication it is exclusively stated that the first step is reacting the silanol compound with titanium halide and thereafter the reaction product is reacted with an organomagnesium compound. Moreover the reaction of the silanol compound has been carried cut at a lew temperature, preferably at room temperature. In our tests we have found that the catalysts described in this publication are not suitable for polymerizing propylene or other a-olefins.

According to the present invention it has been found that, in order to achieve active catalyst components for propylene polymerization catalysts it is necessary to change the preparation steps of EP 104374 and to use essentially higher temperatures during the reaction with the silanol compound. The invention concerns thereby a catalyst component for use in unsupported Ziegler-Natta catalyst compositions for the polymerization of α-olefins having at least 3 carbon atoms, said catalyst being obtained by treating an organnomagnesium compound without chlorine with solid silane compounds containing one or two hydroxyl groups and then with titanium halide compounds and characterized in that said treatment of organomagnesium compound is carried out by first treating with said silane compound in a temperature of 60-110 °C and thereafter with titanium halide compound optionally together with an electron donor compound.

The organic Mg-compound according to the invention does not contain halogen atoms. Suitable magnesium conpounds are magnesium dialkyl compounds such as ethylbutylmagnesium, di butylmagnesium, diisobutyl- magnesium, dihexylmagnesium, dioctylmagnesium, didecylmagnesium.

Preferred magnesium dialkyls are ethylbutylmagnesium and n-butyl-[1- methylpropyl]magnesium plus diethylmagnesium.

The silanoe comp ound can contain one or two hydroxyl groups and it does not contain chlorine. Thus the silanoe compound is an organically substituated silanediol or silanol. The subsrtitution group is aromatic, preferably a phenyl group.

The most preferred silanols are triphenyl silanol and diphenyl silanediol.

The reaction between the silanoe and the magnesium alkyl seems to fix the magnesium alkyl to the silan atom through an oxygen bridge, e.g. "Si - O - MgR' - ". In the second step a substitution between magnesium alkyl and titanium chloride seems to take place, with formation of a compound of the type " Si-O-TiCl₃", which is soluble in excess titanium tetrachloride. The reaction time is rather short, from a couple of minutes to a few hours. The important point is that the temperature is rather high, namely over 60 °C, preferably between 60-110 °C. The molar amount of the Mg-compound is preferably lower than the molar amount of silane compound when using magnesium dialkyl and diphenyl silanediol.

The titanation is carried out in the temperature of 60-110°C, preferably 80°C.

During the titanatiαn so called internal electron donor (Lewis-base) can be added to the catalyst component. This improves the yield and the isotacticity index. Suitable donors are esters of aromatic, preferably phtalic acids and hydrosilane clerivatives. The preferred donor is diisob utylphtalate.

The particles in the catalyst components according to the invention have the shape of diphenylsilanediol or of triphenylsilanol used in the preparation of the catalyst. When the starting material of the derivative is crystallized in needles, we obtain needle-shaped catalyst which is quite unusual. Because of this replication phenomena the catalyst will produce in the polymerization process needle-like, easily flowing polymer particles.

The catalyst components according to the invention can be used for the polymerization of α-olefins having at least 3 carbon atoms. The catalyst components can be activated by known manner with a cocatalyst such as alkyl lithium, alkyl magnesium, alkyl aluminium, ethyl aluminium halide or alkyl zinc. The activation can take place within or outside the polymerization reactor.

Basically the catalyst compositions obtained in a very simple and new way, as herein described, provide high yield and high isotacticity index in the polymerization of α-olefins, preferably propylene and butene. Khown modifications of the polymerization process are also possible, such as adding hydrogen to the monomer feed or to the polymerization reactor in order to modify the properties of the polymer, such as melt flow index.

Following examples are intended to illustrate the invention. Example 1

A catalyst component was prepared in a 700 ml glass reactor equipped with a stirring system, temperature control and kept under nitrogen.

Into the reactor were introduced 20g of diphenylsilanediol and 200 ml of dried (without air) heptane at room temperature and 69 ml of a solution of DBME (Dib utylmagnesium -E, Lithium Corporation of Europe Ltd, a mixture of n-butyl-1-methylpropyl-Mg and diethyl-Mg) in heptane (content of DBME is 9,94 g). The solution was added under agitation drop by drop during about 15 minutes at the roam temperature. After the total amount of DBME had been introduced to the silanediol solution the temperature was raised to 95 °C and was kept at this temperature for two hours. Then the slurry was cooled to the room temperature and the agitation was stopped. After syphoning 200 ml of heptane was added under nitrogen and agitation. The agitation was stepped 30 min later and the diluent was removed. This washing operation was repeated two times. After the last removal of heptane 250ml of TiCI₄ was added at the room temperature. The colour of the slurry changed slightly from white to brown. Then 1,95 of DIBF (di-isobutylphalate) was introduced drop by drop. The temperature was increased to 80 °C, where it was kept for two hours under agitation.

The sedimentation of the slurry after the agitation was stopped was very fast. The liquid was removed by siphoning and 250 ml of TiCl₄ was added. The slurry was kept under agitation at 80 °C for two hours. Then the liquid was removed as above. Finally the product was washed by heptane. Two treatments were carried out with 250 ml of heptane for two hours at 80°C and three additional times at the room temperature.

Into a 2 litre polymerization reactor containing 1300ml dry heptane were introduced 30 mg the catalyst system which was pretreated by mixing in heptane the Al-alkyl compound (triethyl-Al)and the Lewisbase (external electron donor), which was diphenyldimethoxysilane. The molar ratio Al:donor was 10:1 and the catalyst component was prepared as described above.

The Al-Ti molar ratio was 200:1. Propylene was polymerized under following conditions: propylene partial pressure 9,7 bar, hydrogen partial pressure 0,3 bar, temperature 70°C and polymerization time 3 heυrs.

The composition and the properties of the catalyst component and the polymer obtained are presented in Table 1.

Example 2

A catalyst component was prepared as in Example 1 except that butyl octyl magnesium was used as alkyl magnesium. Propylene was polymerized as in Example 1. The composition and the properties of the catalyst component and the polymer obtained are presented in Table 1.

Example 3

A catalyst component was prepared as in Example 1 except that the reaction between silanediol and alkyl magnesium was carried cut at 60 °C. Propylene was polymerized as in Example 1. The composition and the properties of the catalyst component and the polymer obtained are presented in Table 1.

Example 4

A catalyst component was prepared as in Example 1 except that the reaction between silanediol and alkyl magnesium and the titanation were carried cut at 60°C. Propylene was polymerized as in Example 1. The composition and the properties of the catalyst component and the polymer obtained are presented in Table 1. Example 5

A catalyst component was prepared as in Example 1 except that the reaction between silanediol and alkyl magnesium was carried cut at 60°C and the titanation at 110°C. Propylene was polymerized as in Example l. The composition and the properties of the catalyst component and the polymer obtained are presented in Table 1.

Example 6

A catalyst component was prepared as in Example 1 except that triphenyl silanol was used as the silane compound. Propylene was polymerized as in Example 1. The composition and the properties of the catalyst component and the polymer obtained are presented in Table 1.

Example 7

A catalyst component was prepared as in Example 3 except that triphenyl silanol was used as the silane compound and that the internal donor was not utilized. Propylene was polymerized as in Example 1. The composition and the properties of the catalysts component and the polymer obtained are presented in Table 1.

Example 8

1-butene was polymerized in a 2 litre gas phase reactor which was equipped with a screening glass and a spiral stirrer. As a fluidized bed material it was used polypropylene (30 mg ICI GW 521 E), which had been dried in a vacuum oven in 60°C for 1-2 days. For the prepolymerization the reactor was charged with 51,4 mg of the transient metal catalyst component from the Example 1 containing 0,017 mol titanium, 863,211 of triisobutyl-Al cocatalyst containing 3,434 mmol aluminium and 39,211 of diphenyl metoxysilane in pentane as external donor. Al:Ti molar proportion was 200:1 and Al:donor molar proportion was 20:1. The mixture was heated to 40°C and then the pentane was evaporated during about 10 min. The reactor was cooled and the feeding of butylene into the reactor with the partial pressure of 2 bar was started. The polymerization took place in 30 minutes at 30°C and the speed of the stirrer was 750 rpm.

For the polymering the temperature was raised to 54°C and the butylene partial pressure to 5 bar. Hydrogen was int roduced by partial pressure of 0,1 bar. The speed of the stirrer was 900 rpm during the polymerization.

After the polymerizing time of 3 hours 73 g polybutylene was obtained with the isotacrticity index of 96,8%. The activity of the catalyst was 1,4 kg PB/g cat or 89 log PB/g Ti.

Comparative example 1

According to the method described in the European patent application EP 104374 on page 10, it was carried out following polymerizations with or without using an internal electron donor. Ph₃SiOH was treated by BOMΑG (=butyl octyl-Mg) with the molar proportion of 1:1 in a heptane solution (about 5g components in 100 ml heptane) for 2 hours in the room temperature.

The excess of the solvent was syphonized, the excess amount of TiCl₄ was added and the solution was agitated for 15 min in 100°C. The supernatant liquid was syphonized out and the precipitant was washed 3 times by heptane.

The treating with TiCl₄ was carried out only once. The polymerization of propylene was carried out as in Example 1. The results are presented in Table 2.

Comparative example 2

Catalyst No. 1 presented in Table 1 of the patent application EP 104374 was applied to polymerize propylene. The catalyst component was prepared as follows: 0,07 mol Ph₃SiOH was treated by 100ml toluene after which 5,5 g silica (Davidson 952) was added. The silica had been treated in 700-800 °C.

0,07 mol BOMΑG (20% heptane solution) was added to the mixture, which was then allowed to cool to the room te mperature and the product obtained was washed 3 times with heptane in order to remove the TiCl₄ excess. The catalyst cemponent obtained had the following element contents: Mg=1,8%,Ti=2,7%, Cl=13,7% and Si=14,2%. When this component was used in the polymerization of propylene according to the method presented in Example 1 the activity of the catalyst obtained was 0,32 kg PP/g cat.

Comparative example 3

According to the example 7 of US 4525557 a catalyst c omponent was prepared as follows: 2,7g = 12,5 mmol Ph₂Si (OH)₂ in 60 ml heptane was treated with 36 ml = 25,7 mmol BOMAG for 2 hours in the roam temperature 2,38 g 12,5 mmol TiCl₄ was added in 10 ml heptane drop by drop whereby a dark precipitate was immediately formed. The slurry was stirred in ambient temperature for 2 hours, washed 3 times with the amount of 30 ml heptane and dried in vacuum. The element contents of the catalyst component were Mg = 7,6%, Ti = 7,8%, Cl = 21,8% and Si = 2,84%. When polymerizing propylene using this catalyst cemponent the activity of the catalyst was found to be about 0kg PP/g cat.

Claims

1. A catalyst component for use in unsupported Ziegler-Natta catalyst compositions for the polymerization of α-olefins having at least 3 carbon atoms, said catalyst cemponent being obtained by treating an organomagnesium compound without chlorine with solid silane compounds containing one or two hydroxyl groups and titanium halide compounds, chtracyerized in that said treatment of organomagnesium compound is carried cut by first treating with said silane compound at a temperature of 60-110°C and ther eafter with titanium halide compound opticnally together with an electron donor compound.

2. A catalyst component according to claim 1, cha r a cte ri ze d in that said organomagnesium compound containing no chlorine is a dialkyl magnesium compound, wherein the alkyl groups are same or different groups conta ining 2-10 carbon atoms.

3. A catalyst component according to claims 1-2, cha racterized in that said silanoe compound containing one or two hydroxyl groups is selected from triphenyl silano and diphenyl silanediol.

4. A catalyst component according to claims 1-3, characterized in that said titanium halide is titanium tetrachloride.

5. An unsupported catalyst composition for polymerizing α-olefins having at least 3 carbon atoms, which comprises (1) a catalyst component obtained by treating an organomagnesium compound without chlorine with solid silane compounds con taining one or two hydroxyl groups and with titanium halide compounds, (2) a cocatalyst comprising hydrogen or alkyl lithium, alkyl magnesium, alkyl aluminium, alkyl aluminium halide or alkyl zinc, and (3) optionally an external donor compound, characterozed in that said treatment of organomagnesium compound is carried out by first treating with said silane compound in a temperature of 60-110 °C and thereafter with titanium halide compound optionally together with an electron donor compound.

6. A process for polymerization of α-olefins containing at least 3 carbon atoms, which process comprises polymerizing said olefins in the presence of a catalyst cemponent according to claim 5.

7. A process according to claim 6, chara cteriz ed in that said olefin is propylene or butylene.