JP3370188B2 - Olefin polymerization catalyst - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION

FIELD OF THE INVENTION The present invention relates to an olefin polymerization catalyst. More specifically, the present invention provides a polymer having high activity and high stereoregularity when applied to the polymerization of an olefin having 3 or more carbon atoms, and particularly a polymer having a small molecular weight (that is, MFR The present invention relates to a catalyst which has high stereoregularity even if it is produced under a polymerization condition that gives a large polymer, for example, an MFR of 50 or more.

[0002]

2. Description of the Related Art Conventionally, a solid component containing titanium, magnesium, halogen and, if necessary, an electron donating compound, a catalyst for olefin polymerization comprising an organoaluminum compound and optionally an electron donating compound are used to obtain a high yield. It is known that polymers with high stereoregularity can be produced at high rates (ie, high catalytic activity).

Recently, when molding a polyolefin polymer, from the viewpoint of economy, it is required to improve the molding speed in order to improve the molding cycle. For that purpose, it is necessary that the polymer has a small molecular weight, but even when the molecular weight is small, the conventional high stereoregularity is required. This is because unless the polyolefin polymer has high stereoregularity, it is difficult to obtain sufficient performance required as a molding material, for example, rigidity.

However, in the conventionally known catalysts, the stereoregularity of the polymer that can be produced decreases as the molecular weight decreases, that is, the MFR increases. For example, when a polymer having a relatively large molecular weight (for example, MFR = 1) is produced, a polymer having high stereoregularity is obtained, but a condition for producing a polymer having a small molecular weight (for example, MFR = 50 or more) In that case, the stereoregularity is lowered and it is often difficult to obtain a highly stereoregular polymer.

Therefore, in order to solve the above-mentioned problems, for example, a method of using a large amount of an electron-donating compound as an external donor can be considered. In that case, however, the activity is greatly reduced and the cost of the catalyst is increased. Problems are hard to avoid.

[0006]

The problem to be solved by the present invention is to solve the above-mentioned problems. In the present invention, the polymer produced has a relatively small molecular weight, that is, MFR is 50 g. The present invention provides a catalyst capable of obtaining a polymer having high activity and high stereoregularity in / 10 minutes or more.

[0007]

[Means for Solving the Problems]

[Summary of the Invention] <Summary> The present inventors have reached the present invention by discovering that the above-mentioned problems can be solved by using a specific catalyst.

That is, the olefin polymerization catalyst according to the present invention is characterized by comprising the following components (A) and (B). Component (A): A solid component containing titanium, magnesium and halogen as essential components. Component (B): Organoaluminum compound Component (C): Silicon compound represented by the following general formula

[Chemical 2] (Wherein R ¹ is a divalent hydrocarbon group forming a ring with a carbon atom adjacent to a silicon atom, R ² , R ³ and R ⁴
Represents a monovalent hydrocarbon group, and n represents a number of 1 ≦ n ≦ 3).

[Effect] When the catalyst according to the present invention is used,
A polymer with high activity and high stereoregularity is obtained. Moreover, the molecular weight of the polymer is relatively small, that is, the MFR is 5
At 0 g / 10 minutes or more, a polymer having high stereoregularity can be obtained. The reason why such an effect is exhibited is not clear at present, but it is considered that a specific silicon compound component is used at the time of polymerization.

[Detailed Description of the Invention] <Olefin Polymerization Catalyst> The olefin polymerization catalyst according to the present invention comprises specific components (A), (B) and (C). Here, "consisting of" means that the components are listed (that is, (A), (B)).
And (C) does not mean that the purposeful coexistence of the fourth component is not excluded.

<Component (A)> The component (A) used in the present invention is a solid component containing titanium, magnesium and halogen as essential components. Where T
With respect to i, Mg and halogen, "containing these as essential components" means that other than the three listed components may contain other purposeful elements. Each of these elements has its own purpose. It means that these elements may exist as any arbitrary compound, and that these elements may exist as bonded to each other. The solid components themselves containing titanium, magnesium and halogen are known. For example, JP-A-53-45688 and 5
No. 4-3894, No. 54-31092, No. 54-39.
No. 483, No. 54-94591, No. 54-11848.
No. 4, No. 54-131589, No. 55-75411.
No. 55, No. 55-90510, No. 55-90511, No. 55-127405, No. 55-147507, No. 5
5-155003, 56-18609, 56-
70005, 56-72001, 56-869
05, 56-90807, 56-155206.
No. 57, No. 57-3803, No. 57-34103, No. 5
7-92007, 57-12003, 58-
No. 5309, No. 58-5310, No. 58-5311
No. 58, No. 58-8706, No. 58-27732, No. 5
No. 8-32604, No. 58-32605, No. 58-6.
7703, 58-117206, 58-127
708, 58-183708, 58-1837.
09, 59-149905, 59-14990.
Those described in each publication of No. 6 are used.

As the magnesium compound used as the magnesium source in the present invention, magnesium dihalide, dialkoxy magnesium, alkoxy magnesium halide, magnesium oxyhalide, dialkyl magnesium, magnesium oxide, magnesium hydroxide, magnesium carboxylate, etc. Can be given. Among these, magnesium dihalide and dialkoxy magnesium are preferable.

The titanium compound serving as the titanium source has a general formula of Ti (OR ⁸ ) _4-p X _p (wherein R ⁸ is a hydrocarbon residue, preferably having about 1 to 10 carbon atoms, X
Represents halogen and p represents a number of 0 ≦ p ≦ 4). As a specific example, TiCl
₄ , TiBr ₄ , Ti (OC ₂ H ₅ ) Cl ₃ , Ti (O
C ₂ H ₅ ) ₂ Cl ₂ , Ti (OC ₂ H ₅ ) ₃ Cl, Ti
_{(O-iC 3 H 7)} Cl 3, Ti (O-nC 4 H 9) C
_{l 3, Ti (O-nC} 4 H 9) 2 Cl 2, Ti (OC 2
H ₅ ) Br ₃ , Ti (OC ₂ H ₅ ) (OC ₄ H ₉ ) ₂ C
_{l, Ti (O-nC 4} H 9) 3 Cl, Ti (O-C 6 H
_{5) Cl 3, Ti (O} -iC 4 H 9) 2 Cl 2, Ti
(OC ₅ H ₁₁ ) Cl ₃ , Ti (OC ₆ H ₁₃ ) Cl ₃ , T
_{i (OC 2 H 5) 4} , Ti (O-nC 3 H 7) 4, Ti
_{(O-nC 4 H 9)} 4, Ti (O-iC 4 H 9) 4, T
_{i (O-nC 6 H 13} ) 4, Ti (O-nC 8 H 17) 4,
Such as Ti _{[OCH 2 CH (C 2 H 5} ) C 4 H 9 ] _4.

Further, TiX '_Four(Where X'is a halogen
(Indicated by a
An object can also be used as a titanium source. Such a minute
Specific examples of the child compound include TiCl_Four・ CH₃COC₂
H_Five, TiCl_Four・ CH₃CO₂C₂H_Five, TiCl_Four
・ C₆H_FiveNO₂, TiCl_Four・ CH₃COCl, Ti
Cl_Four・ C₆H_FiveCOCl, TiCl_Four・ C₆H_FiveCO
₂C₂H_Five, TiCl _Four・ ClCOC₂H_Five, TiCl
_Four・ C_FourH_FourO etc. are mentioned.

Further, TiCl ₃ (including those obtained by reducing TiCl ₄ with H ₂ , reduced with Al metal, reduced with an organometallic compound, etc.), TiBr ₃ , Ti
It is also possible to use titanium compounds such as (OC ₂ H ₅ ) Cl ₂ , TiCl ₂ , and dicyclopentadienyl titanium dichloride.

Among these titanium compounds, tetravalent titanium compounds, particularly TiCl ₄ , Ti (OC ₄ H ₉ ) ₄ ,
Ti (OC ₂ H ₅ ) Cl _{3 and the} like are preferable.

Halogen is the above-mentioned magnesium and
(Or) is supplied from titanium halogen compounds
Common, but other halogen sources such as AlCl₃,
AlBr₃, Al (C₂H_Five) Cl₂, Al (OC
H₃)₂Cl, etc. Aluminum halides and SiC
l_Four, Si (CH₃) Cl₃, Si (i-C₃H₇)₂
Cl ₂, Etc. Silicon halides, PCl_Five, Etc.
Halide of WCl₆, MoCl_Five,, etc.
It can also be supplied from a known halogenating agent.

The halogen contained in the catalyst component may be fluorine, chlorine, bromine, iodine or a mixture thereof, with chlorine being particularly preferred.

The solid components used in the present invention are the above-mentioned essential components.
In addition to Al (O-iC₃H₇)₃Aluminum compound such as
Thing and B (OCH₃)₃, B (OC₂H_Five)₃, B
(OC ₆H_Five)₃Use of other compounds such as boron compounds such as
Is also possible, these are aluminum and boron etc.
It can be left as a component in the solid component.

Further, when producing this solid component,
It can also be produced using a known electron donor as an internal donor, which is a preferred embodiment.

The electron donors (internal donors) that can be used for the production of this solid component are alcohols, phenols, ketones, aldehydes, carboxylic acids, esters of organic and inorganic acids, ethers, acid amides. And oxygen-containing electron donors such as acid anhydrides, nitrogen-containing electron donors such as ammonia, amines, nitriles, and isocyanates.

More specifically, (a) methanol, ethanol, propanol, pentanol, hexanol,
Octanol, dodecanol, octadecyl alcohol, benzyl alcohol, phenylethyl alcohol,
C1-C18 alcohols such as isopropylbenzyl alcohol, (b) phenol, cresol,
6 to 2 carbon atoms which may have an alkyl group such as xylenol, ethylphenol, propylphenol, isopropylphenol, nonylphenol and naphthol
5 phenols, (c) acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, benzophenone and other ketones having 3 to 15 carbon atoms, (d)
Aldehydes having 2 to 15 carbon atoms such as acetaldehyde, propionaldehyde, octyl aldehyde, benzaldehyde, tolualdehyde, naphthaldehyde,
(E) Methyl formate, methyl acetate, ethyl acetate, vinyl acetate, propyl acetate, octyl acetate, cyclohexyl acetate, cellosolve acetate, ethyl propionate, methyl butyrate, ethyl valerate, ethyl stearate, methyl chloroacetate, ethyl dichloroacetate, Methyl methacrylate, ethyl crotonate, cyclohexane, ethyl carboxylate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, octyl benzoate, cyclohexyl benzoate, phenyl benzoate, benzyl benzoate, cellosolve benzoate. Methyl toluate, ethyl toluate, amyl toluate, ethyl ethyl benzoate, methyl anisate, ethyl anisate, ethyl ethoxybenzoate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate,
γ-butyrolactone, α-valerolactone, coumarin,
C2 to C20 organic acid esters such as phthalide and ethylene carbonate, (f) ethyl silicate, butyl silicate,
Phenyltriethoxysilane, t- butyl methyl dimethoxy _{silane, C 2 H 5 C (CH} 3) 2 Si (OC
₂ H ₅ ) ₂ and other inorganic acid esters such as silicates, (to) acetyl chloride, benzoyl chloride,
Acid halides having 2 to 15 carbon atoms such as toluic acid chloride, anisic acid chloride, phthaloyl chloride and isophthaloyl chloride, (thi) methyl ether, ethyl ether,
Ethers having 2 to 20 carbon atoms such as isopropyl ether, butyl ether, amyl ether, tetrahydrofuran, anisole and diphenyl ether, acid amides such as (li) acetic acid amide, benzoic acid amide and toluic acid amide, (nu) methylamine, ethylamine , Diethylamine, tributylamine, piperidine, tribenzylamine, aniline, pyridine, picoline, tetramethylethylenediamine, and other amines, (l) acetonitrile, benzonitrile, tolunitrile, and other nitriles. Two or more kinds of these electron donors can be used. Among these, organic acid esters, inorganic acid esters and organic acid halides are preferable, and phthalic acid ester, acetic acid cellosolve ester, phthalic acid halide and silicic acid ester are particularly preferable.

Production of Component (A) Component (A) is prepared by contacting each component constituting component (A), or optionally the above-mentioned optional components with each other stepwise or temporarily, preferably in the middle and ( Or) It can be prepared by finally washing with an organic solvent such as a hydrocarbon or a halohydrocarbon. The contact condition of each component constituting the above-mentioned component (A) may be any condition as long as the effect of the present invention is recognized, but the following conditions are generally preferable. The contact temperature is about -50 to 200 ° C, preferably 0 to 100 ° C. Examples of the contacting method include a mechanical method using a rotary ball mill, a vibration mill, a jet mill, a medium stirring pulverizer, etc., and a method of contacting by stirring in the presence of an inert diluent. Examples of the inert diluent used at this time include aliphatic or aromatic hydrocarbons and halohydrocarbons, and polysiloxanes.

The amount of each component constituting the component (A) may be any amount as long as the effects of the present invention are recognized, but in general, the following range is preferable.

The amount of titanium compound used is 1 × 10 ^-4 to 1 in molar ratio with respect to the amount of magnesium compound used.
The range of 000 is good, and the range of 0.01 to 10 is preferable. When a compound therefor is used as a halogen source, the amount used is 1 × 10 6 in molar ratio with respect to the amount of magnesium used, regardless of whether the titanium compound and / or the magnesium compound contains halogen. The range of ^{-2 to} 1000 is preferable, and the range of 0.1 to 100 is preferable. The amount of aluminum and boron compound used is 1 × 10 ⁻³ in terms of molar ratio with respect to the amount of magnesium compound used.
The range of -100 to 100 is preferable, and the range of 0.01 to 1 is preferable.

When the electron-donating compound is used, its amount is preferably in the range of 1 × 10 ^-3 to 10 with respect to the amount of the above-mentioned magnesium compound to be used, and preferably 0.01 to 5. Within the range of.

Component (B) The organoaluminum compound used in the present invention is a compound represented by the following general formula. R ⁵ _3-m AlX _m (wherein R ⁵ has 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms)
Hydrocarbon residue, X is hydrogen or halogen, and m is 0
≤ m ≤ 2 respectively) Specific examples of such a compound include (a) trialkyl such as trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum and tridecylaluminum. Alkyl aluminum halides such as aluminum, (b) diethyl aluminum monochloride, diisobutyl aluminum monochloride, ethyl aluminum sesquichloride, ethyl aluminum dichloride, (c) diethyl aluminum hydride,
Diisobutylaluminum hydride, and of these, (a) trialkylaluminum is preferable.

In addition to these organoaluminum compounds (a) to (c), other organometallic compounds such as R ⁶ _3-q Al
Alkyl represented by (OR ⁷ ) _q (wherein 1 ≦ q ≦ 3, R ⁶ and R ⁷ may be the same or different and are a hydrocarbon residue having 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms). Aluminum alkoxide can also be used together.

For example, combination of triethylaluminum and diethylaluminum ethoxide, combination of diethylaluminum monochloride and diethylaluminum ethoxide, combination of ethylaluminum dichloride and ethylaluminum diethoxide, triethylaluminum and diethylaluminum ethoxide. It can be used in combination with diethyl aluminum chloride. Further, alumoxanes such as methyl alumoxane, ethyl alumoxane, isobutyl alumoxane and the like can also be used.
When the organoaluminum compound is used in combination, it is particularly preferably used in combination with trialkylaluminum. That is, (a)
And (ii) and (ii) and (iii), (ii) and alkyl aluminum alkoxide, and (ii) and alumoxane.

Component (C) The silicon compound used in the present invention is represented by the following general formula.

[Chemical 3] (Wherein R ¹ is a divalent hydrocarbon group forming a ring with a carbon atom adjacent to a silicon atom, R ² , R ³ and R ⁴
Represents a monovalent hydrocarbon group, and n represents a number of 1 ≦ n ≦ 3). The silicon compound may be a mixture of a plurality of compounds of the formula.

Here, R ¹ is a monovalent hydrocarbon group, which is usually a divalent hydrocarbon group having 4 to 20 carbon atoms, preferably 4 to 10 carbon atoms, particularly 4 to 7 carbon atoms, and a silicon atom. It forms a cyclic hydrocarbon with the carbon atom adjacent to. R
² is a monovalent hydrocarbon group, which is usually a branched or linear saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, and particularly 1 to 6 carbon atoms. R ³ is a monovalent hydrocarbon group,
Usually, it is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. R ⁴ is a hydrocarbon residue, which usually has 1 to 1 carbon atoms.
6, preferably 1 to 4 aliphatic hydrocarbon residues. Specific examples of the silicon compound that can be used in the present invention are as follows.

[0032]

[Chemical 4]

Regarding the method of using the components (A) to (C) used in the present invention, as long as the effect of the present invention is recognized,
Although it can be arbitrary, the following methods are generally considered. The usage ratio of the components (A) to (C) is preferably within the following range. The amount ratio of the component (A) and the component (B) is the molar ratio of the titanium component in the component (A) and the component (B) (Al / T
i ratio) of 0.1 to 10,000, preferably 1 to 1,0
It is within the range of 00. The amount ratio of the component (B) and the component (C) is 0.01 to 100 in terms of molar ratio (Si / Al ratio),
It is preferably within the range of 0.1 to 10. Ingredient (A)
The contact method of (C) may be any method as long as the effect of the present invention is recognized, but when introduced into the polymerization tank,
It is also possible to contact the components (A), (B) and (C) in advance, or it is possible to introduce the components (A), (B) and (C) separately. It is also possible to use the components (A) and (B), the components (A) and (C), and the components (B) and (C) in contact with each other in advance.

<Use of Catalyst / Polymerization> The catalyst of the present invention is used for olefin polymerization. That is, not only is it applied to ordinary slurry polymerization, but it is also applied to liquid phase solventless polymerization (bulk polymerization), solution polymerization or gas phase polymerization method that does not substantially use a solvent. Also, continuous polymerization,
It can also be applied to batch polymerization or prepolymerization. As the polymerization solvent in the case of slurry polymerization, hexane, heptane, pentane, cyclohexane, benzene,
Saturated aliphatic or aromatic hydrocarbons such as toluene may be used alone or as a mixture. Polymerization temperature is from room temperature to 150
° C. approximately, preferably 50 to 100 ° C., the polymerization pressure is atmospheric pressure ~300kg / cm ^2, preferably about atmospheric pressure to
It is 50 kg / cm ² , and hydrogen can be supplementarily used as a molecular weight regulator at that time.

Further, in order to control the stereoregularity of the obtained polymer, a known ester as a fourth component at the time of polymerization,
An electron-donating compound such as ether or amine can also be used. In the case of slurry polymerization, the amount of component (A) used is preferably in the range of 0.001 to 0.1 gram, and component (A) / liter solvent.

The α-olefins polymerized by the catalyst system of the present invention have the general formula R--CHCH ₂ (wherein R is hydrogen or a hydrocarbon residue having 1 to 10 carbon atoms, and a branched group is May be present). Specifically, there are olefins such as ethylene, propylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1. Preferred are ethylene and propylene.
In addition to homopolymerization of these α-olefins, copolymerization,
For example, it is possible to copolymerize propylene with up to 30% by weight, based on propylene, of the abovementioned olefins, in particular ethylene. Copolymerization with other copolymerizable monomers (for example, cyclic olefin, diolefin, etc.) can also be performed.

In the catalyst system of the present invention, particularly when homo- or copolymerization of propylene is carried out, the molecular weight is low, that is, the MFR is high, for example, 50 to 300 g / 10 min, preferably 50 to 300 g / 10 min.
High stereoregularity can be obtained even with a propylene polymer of 100 g / 10 min.

[0038]

【Example】

Example-1 [Production of component (A)]
200 ml dehydrated and deoxygenated n-heptane
Was introduced, and then MgCl₂0.4 mol and Ti
(O-nC_FourH ₉)_FourWas introduced at 0.8 mol and heated at 95 ° C for 2
Reacted for hours. After the reaction was completed, the temperature was lowered to 40 ° C. and then
Ide methylhydropolysiloxane (20 centistoke
48 ml) and let them react for 3 hours
It was The solid component produced was washed with n-heptane. Just
In a flask thoroughly replaced with nitrogen, and purify in the same manner as above.
50 ml of n-heptane was introduced and synthesized as above.
0.24 mol of the obtained solid component was introduced in terms of Mg atom.
Then add 25 ml of n-heptane to SiCl_Four0.
Mix 4 moles and introduce into flask at 30 ℃ for 30 minutes
Then, the mixture was reacted at 70 ° C. for 3 hours. After the reaction is completed, n-hep
Washed with tan. Then n-heptane 25 ml
SiCl_Four8 ml by introducing 10 ml into the flask
The reaction was carried out at 0 ° C for 6 hours. After completion of the reaction, with n-heptane
It was thoroughly washed to obtain the component (A). This product contains titanium
The amount was 2.7% by weight.

[Polymerization of Propylene] In a stainless steel autoclave having an internal volume of 1.5 liter equipped with a stirrer and a temperature controller, 500 ml of sufficiently dehydrated and deoxidized n-heptane was added as component (B) 125 mg of triethylaluminum. , As component (C)

[Chemical 5] And 15 mg of the component (A) produced above, then 400 ml of hydrogen were introduced, and the temperature was raised.
Polymerization operation was performed under the conditions of polymerization pressure = 5 kg / cm ² G, polymerization temperature = 75 ° C., and polymerization time = 2 hours. After the polymerization was completed, the obtained polymer slurry was separated by filtration and the polymer was dried. As a result, 182.3 g of polymer was obtained. Further, 0.18 g of polymer was obtained from the filtrate. From the boiling heptane extraction test,
All products I. I (hereinafter abbreviated as T-I.I) was 99.1 weight percent. MFR = 68.2 g / 10 minutes,
The bulk density of the polymer was 0.48 g / cc.

Example-2 [Production of Component (A)] Substituted with sufficiently purified nitrogen 5
In a 00 ml flask, place Mg (OC ₂H_Five)₂
20 g, 100 milliliters of purified toluene
Then TiCl_FourIntroduce 60 ml, 70
The temperature was raised to ℃ and then 3.6 milliliters of cellosolve acetate was added.
Was introduced, the temperature was raised to 100 ° C., and the reaction was performed for 3 hours. reaction
After completion, the reaction was washed thoroughly with n-heptane. That
Later, TiCl_FourIntroduce 100 ml, 110 ℃
And reacted for 3 hours. After the reaction is complete, n-heptane is sufficient
It was washed to obtain Component (A). Titanium content = 2.1
% By weight, cellosolve acetate content = 13.1% by weight
It was

(Polymerization of Propylene) In the polymerization of propylene of Example-1, as the component (C)

[Chemical 6] Polymerization of propylene was carried out in exactly the same manner except that 23.9 mg was used. 203.9 grams of polymer were obtained, and the T-I. I = 98.3% by weight, MFR = 5
8.4 g / 10 minutes, polymer bulk specific gravity = 0.44 (g /
u).

Comparative Examples 1-2 In the polymerization of propylene of Example-1, the polymerization was carried out in the same manner except that the silicon compound shown in Table-1 was used as the component (C). The results are shown in Table-1.

[0043]

[Table 1]

Examples-3 to 7 Polymerization of propylene of Example-1 was carried out in exactly the same manner except that the silicon compound shown in Table 2 was used as the component (C). The results are shown in Table-2.

[0045]

[Table 2]

[Brief description of drawings]

FIG. 1 is intended to aid in understanding the technical content of the present invention regarding a Ziegler catalyst. >

─────────────────────────────────────────────────── --Continued from the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08F 4/64-4/658 CA (STN)

Claims (2)

(57) [Claims] 1. The following components (A), (B) and (C):
An olefin polymerization catalyst comprising: Component (A): A solid component containing titanium, magnesium and halogen as essential components. Component (B): Organoaluminum compound Component (C): Silicon compound represented by the following general formula: (Wherein R ¹ is a divalent hydrocarbon group forming a ring with a carbon atom adjacent to a silicon atom, R ² , R ³ and R ⁴
Represents a monovalent hydrocarbon group, and n represents a number of 1 ≦ n ≦ 3). 2. The component (C), wherein R ¹ is a divalent hydrocarbon group having 4 to 20 carbon atoms, R ² is a branched or straight-chain saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms, and R ^{2. 3} is carbon number 1-10
2. The catalyst according to claim 1, which is a silicon compound in which the aliphatic hydrocarbon group and R ⁴ are aliphatic hydrocarbon groups having 1 to 6 carbon atoms.