JPS5812285B2 - Ethylene snail - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Background of the Invention The present invention relates to a method for producing an ethylene polymer that has high catalytic activity and exhibits novel properties.

Conventionally, ethylene polymers produced by ordinary Ziegler catalysts have low activity per transition metal component, and a large amount of transition metal remains in the ethylene polymer.

It is also known that this catalyst residue adversely affects the hue, thermal stability, etc. of ethylene polymers.

Therefore, when using a typical Ziegler catalyst, purification steps such as decomposition with alcohol and neutralization with alkali are required in order to remove the catalyst residue from the ethylene polymer.

This causes an increase in manufacturing costs in industrial production and is extremely inconvenient in terms of stable production.

Furthermore, if ethylene is polymerized using this Ziegler catalyst, polyethylene that has extremely high linearity and density and is suitable for injection molding can be obtained.

However, in order to obtain this type of polyethylene with a high melt index that can be injection molded, it is necessary to control the average molecular weight using hydrogen, etc.
In particular, it is unsatisfactory for applications such as hollow containers that require high resistance to environmental stress cracking.

It is known that low-density products with a relatively low content of branches in the main chain are better for such applications than high-density products with extremely high linear chains. In order to obtain it, it is necessary to copolymerize it with an α-olefin such as propylene or putene-1.

However, the use of a large amount of hydrogen and the copolymerization have many disadvantages, such as significantly complicating the polymerization equipment and increasing the cost of producing the copolymer since hydrogen and the copolymer are relatively expensive.

(3) Summary of the invention (Summary) This invention solves the above-mentioned problems of catalyst activity and relies on the use of large amounts of hydrogen and copolymerization. With the aim of producing moldable polyethylene of relatively low density advantageously for industrial production without the need for This objective is achieved by using a chemically free alkoxytitanium compound and a solid composition obtained by co-milling a compound selected from esters.

Therefore, the method for producing an ethylene polymer according to the present invention is characterized in that ethylene is brought into contact with a catalyst consisting of a combination of component I), component (2), and component (2) below for polymerization.

■) Solid composition obtained by mixing and pulverizing the following components (1) to (3) (1) Titanium trichloride (2) Magnesium halide (3) Silicon compounds and esters represented by the following general formula A compound selected from SiXn(OR)+-n (where X is a hydrogen atom, a halogen atom, or a hydrocarbon residue, R is the same or different hydrocarbon residue as X, and n is O~4
) RCOOR' (Here, R and R' are hydrocarbon residues, and may be the same or different.) n) Organoaluminum compound ■) Titanium compound T i (
OR) , x4- n (where R is a hydrocarbon residue, X is a halogen atom, n is 0
(Integer of ~4) (Effects) The catalyst of the present invention has a very high activity, that is, a high yield to catalyst (expressed as the amount of polymer produced relative to the amount of catalyst used). , does not require purification steps such as alkali neutralization.

The transition metal content of the ethylene polymer is T i 0 2 of 20 ppIn or less, a value that hardly affects the quality of the product.

In addition, the density of the ethylene polymerized product produced is 0.900 to 0.
．． 9 7 0 kg/j! - It is possible to control within the range of m3, and there is no need to copolymerize with other α-olefins even in fields where high resistance to “environmental stress cracking” is required.

Furthermore, polyethylene having a low average molecular weight, so-called a polymer suitable for injection molding, can be produced by adding a small amount of hydrogen.

As described above, the present invention has advantages such as omitting the purification process, simplifying the manufacturing equipment, and reducing manufacturing costs.

The effects of the present invention are the above-mentioned component I) (1) and (2).
, (3) Solid composition and components obtained by co-pulverizing ■)
It can only be obtained by using component I) (1
), (2), and (3), even if one component or component (■) is missing, it is insufficient.

For example, as seen in Japanese Patent Publication No. 47-46269, the ingredients! ) When the mixed pulverized mixture of titanium trichloride and magnesium halide of (1) and (2) is used, the catalytic activity is lower than that of the catalyst of the present invention, and the density of the ethylene polymer produced does not decrease.

Also, as seen in Japanese Patent Publication No. 46-33570, titanium or vanadium halides are fixed to hydroxides of metals of Groups ■ to ■ of the periodic table as component (■),
Or, as seen in Japanese Patent Publication No. 44-20988, IVa, Va? The catalyst of the present invention is characterized by high activity compared to catalysts in which halides of Via group transition metals are chemically supported.

As mentioned above, the effects of the present invention are due to the components (1) and (2).
, (3) Solid composition and components obtained by co-pulverizing ■
) can only be obtained by using

Specific explanation of En invention 1. Catalyst A Component I) (1) Titanium trichloride Titanium trichloride includes titanium tetrachloride reduced with hydrogen (T iCA!s (H), l, and titanium metal reduced (T iCA'3 (T )), those reduced with aluminum metal (TiCl3(A)), those reduced with organoaluminium compounds (e.g. titanium trichloride by diethylaluminum chloride reduction), those reduced with silicon hydride compounds (e.g. hydromethylpolysiloxane). There are many other types, such as titanium trichloride (by reduction).

Although the catalytic performance obtained in the present invention is not necessarily the same (there may be a difference in catalytic activity depending on the type of titanium trichloride used), trichlorination of so-called Ziegler catalysts (including Ziegler-Natsuta catalysts) Anything that can be used as a titanium component can be used.

Therefore, this titanium trichloride does not need to be pure T i C 4 , but it can also be one to which 1 mol of AICl 3 has been added, such as TiCl 3 (A) 1 , or to which such auxiliary components have been introduced afterwards. Alternatively, it may unavoidably or intentionally contain a small amount of unreduced TtCl4, overreduced TiCA2, or an oxidation product of a reducing agent.

(2) Magnesium halide MgX2 (X = halogen atom) Specifically, MgF2, MgCl2, MgBr2, Mg■
There are 2.

(3) Silicon Compounds Alkoxy silicon compounds and halogenated silicon compounds represented by the following general formula.

SiXn(OR)4+n where X is a hydrogen atom, a halogen atom or a hydrocarbon residue,
R is a hydrocarbon residue that is the same as or different from X, and n is an integer of 0 to 4.

Hydrocarbon residues include straight chain, branched chain, alkyl, cycloalkyl, aralkyl, aryl, alkaryl, etc.
It may be saturated, unsaturated, or cyclic, and the number of carbon atoms is preferably 8 or less.

Specific examples include tetramethoxysilane, tetraethoxysilane, tetrapoxysilane, tetrabutoxysilane, tetraphenoxysilane, diethoxydimethylsilane, diisopoxydimethylsilane, triethoxymethylsilane, and dichlorodiethoxysilane. .

Esters represented by the general formula below.

RCOOR' where R and R' are hydrocarbon residues and may be the same or different.

The hydrocarbon residue may be straight chain, branched, saturated, unsaturated, or cyclic, such as alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, alkaryl, aralkyl, etc., and has 1 to 10 carbon atoms. preferable.

Specific examples of esters include ethyl acetate, methyl acetate,
Examples include ethyl benzoate, ethyl acrylate, methyl methacrylate, and methyl salicylate.

The above compounds can be used alone or in combination of two or more.

Quantitative Ratio Ingredients I) The quantitative ratios of (1) to (3) may be arbitrary as long as the effects of this invention are recognized.

Generally, magnesium halides (2) and titanium trichloride (1) of alkoxysilicon, silicon halide, halogenated methane, ester, alcohol ketone, etc. (3)
) is determined based on the activity of the mixed and pulverized catalyst components, the particle size and morphology of the polymer, and the pulverization conditions.

In this catalyst, the molar ratio of magnesium halide to titanium trichloride is 3 or more, preferably 10 to 50, and alkoxy silicon, etc. (3) is 0.1 based on the total weight of the three components.
It is preferable to mix and pulverize in a quantitative range of 1 to 10% by weight, preferably 1 to 45% by weight.

Mixing and Grinding The mixing and grinding of components I) (1) to (3) can be carried out using any grinding equipment that allows intimate contact between the three components.

Since mixing and pulverization should be carried out without contact with moisture or air, rotary ball mills, rod mills, impact mills, vibration mills, and other various mills can be used as long as this point is taken into account.

The degree of mixed pulverization only needs to be sufficient to obtain the desired significant improvement effect of mixed pulverization of the three components (1) to (3). Therefore, from this point of view, the pulverization method, pulverization conditions,
What is necessary is to select the grinding time, etc.

In a vibrating mill or rotary pole mill, etc., the grinding time is determined by the combination of various conditions such as ball filling rate, grinding sample filling rate, ball diameter, rotation speed or vibration frequency, and grinding temperature, and the time required to obtain the desired catalyst composition. Generally, it is possible to obtain a product with sufficiently improved catalytic performance by pulverizing within 100 hours, although the time may vary.

Furthermore, if necessary, pulverization can be carried out either wet or dry.

Regarding the types and amounts of the three components (1) to (3), a typical mixed grinding method is to grind all of them in a mixed state from the beginning. It is also possible to add in portions.

B. Component (2) Organoaluminum compound Any component that can serve as a Ziegler type catalyst component for polymerization of ethylene can be used, but those represented by the following general formula are suitable.

AIRnX3-n1AIRn(OR')3-n where R
and R' are hydrocarbon residues and may be the same or different, X is a halogen atom, and n is 3, 2, 1, 1.5 or 1.

Specific examples include triethylaluminum, triisobutylaluminum, diethylaluminum chloride, diethylaluminum ethoxide, ethylaluminum dichloride, and sesquialuminum chloride, and preferable results are obtained when triethylaluminum and triisobutylaluminum are used.

Quantitative Ratio The quantitative ratio of component I) and component (2) is essentially the same as the quantitative ratio when component I) is ordinary titanium trichloride.

Although a slight difference in catalytic performance may be observed depending on the quantitative ratio, such as a change in catalytic activity, it can generally be used within the following range.

Component II)/Component I) = 0.1 to 100, preferably 1 to
20 (weight ratio).

C. Ingredients ■) Tetravalent titanium compound It is expressed by the following general formula.

Ti(OR)nX4, where R is a hydrocarbon residue, X is a halogen atom, and n is O~
It is an integer of 4.

As the hydrocarbon residue, alkyl groups and aryl groups having 1 to 8 carbon atoms can generally be used, but those derived from lower alcohols having 3 to 4 carbon atoms are preferred.

Specific examples include titanium tetrachloride, titanium tetrabromide, ethyl titanate, isoprobyl titanate, butyl titanate, phenyl titanate, diethoxy dichlorotitanium, dibutoxy dichlorotitanium, and the like.

The quantitative ratio of the density of the produced ethylene polymer is component I) and component ■)
A close relationship is observed in the quantitative ratio.

In detail, the transition metal compound contained in component I) and the component ■
) is related to the quantity ratio.

Depending on the quantitative ratio and the type of tetravalent titanium compound used, slight differences in catalyst activity and density of the ethylene polymer may be observed, but generally it can be used within the following range.

Component 1)/Transition metal compound of component I) = 0.05 to 50
Preferably 0.5 to 20 (weight ratio).

D. It can be carried out in a manner essentially not different from that in the case where the catalyst preparation component (1) is ordinary titanium trichloride.

In other words, the method for supplying the catalyst to the reaction vessel is the following 5.
There is a street.

(a) A method in which component I), component ①) and component I) are separately fed directly into a reaction vessel.

(b) A method in which component I), component (2), and component (2) are mixed in advance in a polymerization solvent and the mixture is fed into a reaction vessel.

(C) A method in which component I) and component (2) are mixed in advance in a polymerization solvent, and component (2) is fed simultaneously or separately into a reaction vessel.

(d) A method in which component (1) and component (2) are mixed in advance in a polymerization solvent and component I) is fed simultaneously or separately into a reaction vessel.

(e) A method in which component I) and component (2) are mixed in advance in a polymerization solvent, and component (2) is fed simultaneously or separately into a reaction vessel.

Although the object of the present invention can be achieved in any of the above methods, if the method of adding component I) after bringing component (i) and component (i) into contact with each other, it is possible to The density of the produced ethylene polymer can be significantly reduced.

It is known that various modifications can be made to the Ziegler catalyst, but in this invention, as long as the spirit thereof is not unduly impaired, component (■), component (■), component (■), and component (■) are used.
For each mixture of component I) and component ■), component I) and component ■), heating, aging, cleaning or addition of other components other than component l), ■), and ■) that improve the catalyst performance, etc. Desired modifications can be made, such as post-processing.

2. The method of the present invention is essentially the same as this type of method for producing ethylene polymers, except that the ethylene polymerization catalyst is as described above.

The catalyst of the present invention can be applied not only to ordinary slurry polymerization, but also to solvent-free polymerization that does not substantially use a solvent, continuous polymerization, batch polymerization, or prepolymerization. also applies.

As the polymerization solvent in the case of slurry polymerization, saturated aliphatic or aromatic hydrocarbons such as hexane, hebutane, cyclohexane, benzene, and toluene may be used alone or in mixtures.

The polymerization temperature is about room temperature to 200℃, preferably 50 to 15℃.
0° C., and hydrogen can be used as an auxiliary molecular weight regulator.

■Experimental Example-1 (1) Production of component I) A stainless steel pot with an internal volume of 1 liter was filled with an apparent volume of 900 ml of 12.7iiφ stainless steel balls, and T iCA'3 manufactured by Toho Titanium Co., Ltd.
(A) (unground) 18g, anhydrous MgCl2170
g and 12 g of silicon tetrachloride are sealed in a nitrogen atmosphere,
It was ground in a vibrating mill for 48 hours.

The amplitude was 5iH and the motor rotation speed was 170 O rpm.

After the pulverization was completed, the mixed and pulverized solid composition was taken out from the pot in the dry box, and about 180 g was weighed.

(2) Polymerization of ethylene Under a nitrogen atmosphere, 500 ml of dry and degassed heptane was placed in a Widmer apparatus with an internal volume of 500 ml, and triethylaluminum (hereinafter abbreviated as TEA) (component n)) was added. 1g,
Tetrabutoxytitanium (hereinafter abbreviated as TBT) (component I)
) and 0.035 g of the solid composition (component I) were added in this order to prepare a catalyst slurry.

After repeating vacuum-ethylene substitution several times into a tempered glass autoclave with an internal volume of 1 liter and equipped with a stirring and temperature control device, the catalyst slurry was introduced from the above-mentioned Widmer device under an ethylene atmosphere.

Polymerization was carried out at a polymerization temperature of 85° C., an ethylene partial pressure of 5 kg/cm 2 , and a polymerization time of 1 hour.

These were kept under the same conditions during the polymerization.

However, as the polymerization progressed, the pressure, which decreased, was kept constant by additionally introducing only ethylene.

After the polymerization was completed, ethylene and hydrogen gas were purged, the contents were taken out from the autoclave, the slurry was thoroughly filtered, and it was dried in a vacuum dryer at 70°C for 24 hours.

210 g of a polymer having a melt index of 50 or more and a true density of 0.9082 was obtained.

Catalyst activity 12001-PE/. ! 9.Component I), C2
H4 atm, hours, 5 7 0 0 0. 9-P
E/gT IC2 H4atm time.

Example-2 (1) Production of component I) In the production of component I) of Example-1, silicon tetrachloride 1
It was produced in the same manner except that 15 g of tetraethoxysilane was used instead of 2 g.

(2) Ethylene polymerization tetrabutoxytitanium 0.037 g, component I) 0.04
8,9, ethylene partial pressure 5.7 kg/d, hydrogen partial pressure o. Example-1 except that the weight was set at 3 kg/crit.
I did the same thing.

Melt index 0.30, true density 145 g of 0.9061 polymer was obtained.

Catalyst activity 550g・PE/g・Component I), C2H4atm 1 hour, 26000g・PE/g・Ti
+3, C2 H4 atm, hours.

Example-3 (1) Production of component I) In the production of component (■) of Example-1, silicon tetrachloride 1
It was produced in the same manner except that 7.8 g of methyl methacrylate was used instead of 2 g.

(2) Polymerization of ethylene 0.037 g of tetrabutoxytitanium and component I) 0.
The same procedure as in Example 1 was carried out except that 05 g of ethylene was used, and the partial pressure of ethylene was 5 kg/cm2 and the partial pressure of hydrogen was 1 kg/cm2.

120 g of a polymer having a melt index of 0.50 and a true density of 0.908 was obtained.

Catalyst activity 480g・PE/g・Component I), C2 H4
atms time, 23000I-PE/g・Ti,C
2 H4 atrn, hours.

Example-4 Using 0.069 g of component 1) produced in Example-2, 0.037 g of tetrabutoxytitanium, and 0.100 g of triisobutylaluminum, the ethylene partial pressure was 5. 7 kg
/cri￥, hydrogen partial pressure 0. The same procedure as in Example 1 was conducted except that the weight was 3 kg/criY.

170 g of a polymer having a melt index of 0.09 and a true density of 0.9392 was obtained.

Catalytic activity 430El-PE/9-component I), C2 H4
atm 1 hour, 21000g-pE/g Tt
- C2H4atm, time.

Example 5 (1) Production of component I) Component I) was produced in the same manner as in Example 1 except that TiCl3 (A) was replaced with TiCl3 (T).

(2) Polymerization of ethylene 0.037 g of tetrabutoxytitanium and component I) 0.
The same procedure as in Example 11 was carried out, except that 05 g of ethylene was used, the ethylene partial pressure was 5 kg/cm2, and the hydrogen partial pressure was 1 kg/cm2.

Melt index 0.20, true density 190 g of 0.9346 polymer was obtained.

Catalyst activity 760g・P E/9・Component I), C2 H4
atm, hour, 3600 (L9-PE/gTi 1
C2H4 ajJ time.

Example-6 Component I) of Example-1 0.05 g, tetrabutoxythi'
) 7 0.0 0 7 5 g, triisobutylaluminum o. using ioo9, ethylene partial pressure 8.
The same procedure as in Example 1 was carried out except that the polymerization temperature was 70° C. and 5 kg/cyrY, hydrogen partial pressure was 1.5 kg/ffl.

Melt index 0.20, true density 0.9277g/
cc, methyl branching degree 22.1/IOOOC polymer 1
80 g was obtained.

Catalytic activity 420g PE/g - component I), C2 H4
atm, time, 20000g・PE/g Tt 1C2
H4 ATM 1 hour.

Example-7 Same as Example-11 except that 0.05 g of component I) produced in Example-2 and 0.02 g of titanium tetrachloride were used, and the ethylene partial pressure was 5 ky/d and the hydrogen partial pressure was 1 ky/ffl. I did the same.

Melt index 0.02, true density 0. 94 5
110 g of polymer No. 5 was obtained.

Catalytic activity 440g-PE/g-component I), C2 H4
atm, time, 21000g・P. E/g・Ti1C2
H4 atm 1 hour.

Comparative Example-1 Component I) was TiCils (A) 5 5■,
Tetrabutoxytitanium 85■ was used as component (2), ethylene partial pressure was 8.0 kg/crA, and hydrogen partial pressure was 2.0 kg/crA. 0k
g/crit, and otherwise carried out in the same manner as in Example-1.

170 g of a polymer having a melt index of 1.0 and a true density of 0.9550 was obtained.

Catalyst activity 390g/PE/. 9.Component I), C2H4a
tm1 hour, 1.600. ! 9 ・PE/gTi+3,
C2H4atm 1 hour.

Examples-8 to 10 Using component I) produced in Example-1 and changing the molar ratio of Ti in tetrabutoxytitanium/component I), the ethylene partial pressure was 5.7 kg/crlL and the hydrogen partial pressure was 0. ．． 3
The same procedure as in Example 1 was conducted except that k9/cat was used.

The results are shown in the table below.

Comparative Example-2 Example-2 except that tetrabutoxytitanium was not used.
Polymerization was carried out in the same manner as in Example 1.

73 g of a polymer having a melt index of 2.4 and a true density of 0.9620 was obtained.

It can be seen that only a polymer with high true density can be obtained in a system that does not use tetrabutoxytitanium.

Catalytic activity 370g PE/g - component I), C2 H4
atm, time, 18000g・PE/. ? -Ti%
C2H4atm, time.

Comparative example-3 Without using tetrabutoxy titanium, ethylene partial pressure 3 kg/
Polymerization was carried out in the same manner as in Example 6 except that crA and hydrogen partial pressure were changed to 7 kg/crit.

40 g of a polymer having a melt index of 0.27, a true density of 0.9550, and 2.0 ethylene branches/1000C was obtained.

It can be seen that only a polymer with high true density can be obtained in a system that does not use tetrabutoxytitanium.

Catalytic activity 210g・PE/g・Component I), C2H4at
m, time, 10000.9-PE/g-Ti+3,
C2 H4 aiJ time.

Example-11 Put 500 ml of hebutane into a Widmer apparatus, add 0.1 g of triisobutylaluminum (Bi', 0.010 g of tetrabutoxytitanium, shake by hand,
The mixture was allowed to stand for a minute, after which component I) was added and introduced into the polymerization tank.

Polymerization was carried out in the same manner as in Example 6 except for the above.

Melt index 0.23, true density 0.9 2 7
8. A polymer having 22.1 ethylene branches/IOOOC was obtained.

Catalyst activity 430g・PE/g・Component I), C2 H4
atm, time, 200000. 9-PE/
g・Ti, C2H4 atm, time.

Example-12 Put 50 ml of heptane into a Widmer apparatus, add 0.10 g of triisobutylaluminum, and component I), shake by hand, leave for 10 minutes, then add 0.010 g of tetrabutoxytitanium, and add 0.10 g of triisobutylaluminum and component I). It was introduced in

Polymerization was carried out in the same manner as in Example 6 except for the above.

A polymer having a melt index of 0.85, a true density of 0.9444, and 5.70 ethylene branches/IOOOC was obtained.

Catalyst activity 560g・PEIg・Component I), C2 H4
atm, hour, 26000g-PE/9-component I), C
2 H4 atm, hours.

As can be seen from Examples 11 and 12 above, when an organoaluminum and a tetravalent titanium compound are brought into contact with each other in advance, the true density of the resulting polymer is significantly reduced by the addition of a small amount of the tetravalent titanium compound. .

Comparative Example-4 (1) Production of component (■) In a nitrogen atmosphere, 15 g of Mg(OH)Cl and T t C 14 2 5 were placed in a four-sided flask with an internal volume of 200 rILl.
ml, heated at 130°C for 1 hour with stirring, cooled, separated the solid, and chemically unfixed Ti.
Heptane washes were performed until CA+ was completely removed.

The solid product contained 0.6% by weight Ti.

(2) Ethylene polymerization component I) 0.1809, TEA 0.5 4 0 p・
Polymerization was carried out in the same manner as in Example 1, except that 0.007 g of tetrabutoxytitanium was used, the ethylene partial pressure was 7 kg/cri, the hydrogen partial pressure was 3 kg/crl, and the polymerization temperature was 80°C.

Melt index 0.30, true density 75 g of 0.9500 polymer were obtained.

Catalytic activity 61-PE/g component I), C2H4atm, time, 1000 (1-PE/9・TiC2H4 in component I
Aim 1 hour.

As can be seen from the comparison with the examples of the present invention, the above activity is as low as 1 or less per component I) and 1 or less per Ti in component I).

Comparative Example-5 Under a nitrogen atmosphere, 500 ml of dry and degassed heptane was placed in a Widmer apparatus with an internal volume of 500 ml, and 0.150 g of triethylaluminum and 0.03 g of tetrabutoxytitanium were added.
0 g was added and introduced into a tempered glass autoclave under slight ethylene pressure.

After stirring for 5 minutes, titanium tetrachloride 0.07! 1 was added to make the ethylene partial pressure 10 kg/cIIt, and polymerization was carried out at 80° C. for 1 hour.

170 g of a polymer having a melt index of 0.30 and a true density of 0.9350 was obtained.

Catalytic activity 220g-PE/g component I), C2 H4 a
tm, time, 880. 9 - TiC2H4atm in PE/g component l for 1 hour.

As can be seen in the examples of the present invention, the activity of the above catalyst is less than 1% per Ti in component I) (the above catalyst = TtCl4), and the activity of the above catalyst is less than 1% per Ti in component (per Ti) low, below envy.

Claims (1)

[Scope of Claims] 1. A method for producing an ethylene polymer, which comprises polymerizing ethylene by bringing it into contact with a catalyst consisting of a combination of the following components 1), 2) and 1). ■) Solid composition obtained by mixing and pulverizing the following components (1) to (3) (1) Titanium trichloride (2) Magnesium halide (3) Silicon compounds and esters represented by the following general formula A compound selected from SiXn(OR)+-n (where X is a hydrogen atom, a halogen atom, or a hydrocarbon residue, R is a hydrocarbon residue that is the same as or different from X, and n is an integer from 0 to 4) RCOOR' (Here, R and R' are hydrocarbon residues and may be the same or different.) ■) Organoaluminum compound ■) Titanium compound T i (
OR) nX4 - n (where R is a hydrocarbon residue, X is a halogen atom, n is O
~4 integer).