JP2002012609A - Method of producing polypropylene polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst that gives polyolefin of high molecular weight and high stereoregularity. SOLUTION: In this invention, polyolefin having high molecular weight and high stereoregularity is produced by using an olefin polymerization catalyst comprising the following component A and component B: The component A: a transition metal compound represented by formula [I] ((M is a transition metal selected from Ti, Zr and Hf; R1 is a 1-6C, monovalent hydrocarbon residue or a Si-including hydrocarbon residue; R2 is a 4-20C, divalent hydrocarbon residue or a Si-including hydrocarbon residue; R3 is a 1-30C, divalent hydrocarbon residue or Si- or Ge-including hydrocarbon residue; X and Y are each H, a halogen, a monovalent 1-20C hydrocarbon residue, N-, O- or Si-including hydrocarbon residue); The component A: an almoxane represented by formula [II] or [III] (m is 4-30; R4 is a monovalent hydrocarbon residue).

Description

DETAILED DESCRIPTION OF THE INVENTION

[Background of the Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a stereoregular polyolefin. Specifically, the present invention provides:
Using a specific metallocene compound, that is, an asymmetric new transition metal compound having a bis-substituted cyclopentadienyl bridge-type bidentate ligand having a bridged structure, and an olefin polymerization catalyst comprising an alumoxane, a stereoregular polyolefin is synthesized. It relates to a method of manufacturing.

[0002]

2. Description of the Related Art As a homogeneous catalyst for olefin polymerization, a so-called Kaminski catalyst is well known. This catalyst is characterized by a very high polymerization activity and a polymer having a narrow molecular weight distribution.

[0003] Transition metal compounds for producing isotactic polyolefins include ethylenebis (indenyl) zirconium dichloride and ethylenebis (4,5,5).
(6,7-Tetrahydroindenyl) zirconium dichloride (Japanese Patent Application Laid-Open No. Sho 61-130314) is known. However, the molecular weight of the produced polyolefin is small. Is low.

It is known that a high molecular weight compound can be produced by using a hafnium compound instead of zirconium (Journal of Molecular Catalysis,
56 (1989) pp. 237-247), this method has a problem of low polymerization activity. Further, dimethylsilylbis-substituted cyclopentadienyl zirconium dichloride and the like are disclosed in JP-A-1-301704, Polymer Preprints, J.
apan vol. 39, No. 6, pp. 1614-1616 (1990), but there is no report of a catalyst that simultaneously satisfies high polymerization activity and high molecular weight.

[0005]

SUMMARY OF THE INVENTION The present invention relates to an extrusion molding,
It is an object of the present invention to provide a polymerization method for obtaining a high-molecular-weight (number-average molecular weight of 70,000 or more) polypropylene-based polymer that can be injection-molded at a high yield.

[0006]

Means for Solving the Problems [Summary of the Invention] <Summary> The present invention has been made as a result of studies to solve the above problems. That is, the present invention relates to a method for producing a propylene-based polymer using an olefin polymerization catalyst comprising the following components (A) and (B). Component (A): a transition metal compound represented by the following general formula [I];

Embedded image (Wherein, M is a transition metal selected from the group consisting of titanium, zirconium and hafnium;
¹ may be the same or different and have 1 to 6 carbon atoms;
A monovalent hydrocarbon residue or a silicon-containing hydrocarbon residue, wherein two R ^{2 's} may be the same or different, and are attached to two adjacent carbon atoms of a five-membered ring ligand; A divalent hydrocarbon residue having 4 to 20 carbon atoms or a silicon-containing hydrocarbon residue, wherein R ³ has 1 to 30 carbon atoms;
Is a divalent hydrocarbon residue or a hydrocarbon residue containing silicon or germanium, wherein X and Y are each independently hydrogen or halogen, or C 1-2
0 is a monovalent hydrocarbon residue or a hydrocarbon residue containing nitrogen, oxygen or silicon. Provided that the substituent R ¹
And the two five-membered ring ligands having R ² are asymmetric with respect to the plane containing M in terms of their relative positions via the group R ³ . ) Component (B) An alumoxane represented by the following general formula [II] or [III].

Embedded image (Where m is a number from 4 to 30, and R ⁴ represents a monovalent hydrocarbon residue)

<Effect> According to the catalyst of the present invention, a stereoregular polyolefin having a high molecular weight can be produced in a high yield. It can be understood that the fact that the inherently high polymerization activity and the increase in the molecular weight were compatible was due to the characteristics of the catalyst of the present invention, for example, the use of an asymmetric metallocene compound, but was unexpected.

[Specific description of the invention] <Catalyst> The present invention provides the following component (A) and component (B)
The present invention relates to a method for producing a stereoregular polyolefin having a high molecular weight in a high yield using an olefin polymerization catalyst comprising Here, “consisting of” means that a third component other than (A) and (B) can be used as long as the effects of the present invention are not impaired.

<Component (A)> (1) One catalyst component (A) used in the present invention is a transition metal compound represented by the following general formula [I].

[0010]

Embedded image (Wherein, M is a transition metal selected from the group consisting of titanium, zirconium and hafnium;
¹ may be the same or different and have 1 to 6 carbon atoms;
It is preferably a monovalent hydrocarbon residue of 1 to 4 or a hydrocarbon residue containing silicon, and two R ^{2 s} may be the same or different, and two of the five-membered ring ligands Is a divalent hydrocarbon residue or a silicon-containing hydrocarbon residue having 4 to 20, preferably 4 to 8 carbon atoms bonded to two adjacent carbon atoms, and R ³ has 1 to 30 carbon atoms. A divalent hydrocarbon residue or a hydrocarbon residue containing silicon or germanium, preferably having 2 to 20 carbon atoms,
And Y are each independently hydrogen or halogen, or C1-20, preferably C1-7,
A divalent, hydrocarbon residue or a hydrocarbon residue containing nitrogen, oxygen or silicon. )

The metallocene compound of the formula [I] used in the present invention is characterized in that two five-membered ring ligands having substituents R ¹ and R ² are represented by the following formulas with respect to the relative position via the group R ³ .
The feature is that it is asymmetric with respect to the plane including M.

[0012] Here, the fact that "in view of the relative position via the group R ^3, is asymmetrical with respect to the plane containing M",

Embedded image Indicate that the two substituted five-membered rings opposed to each other with respect to are not in a mirror image of the entity with respect to the plane including M.

The asymmetric state in that case is roughly classified into 2
There can be types. That is, one of them is a case where the positions of the substituents R ¹ and R ² are not in a mirror image with respect to a plane including M, X, and Y in both substituted 5-membered ring ligands.
In that case, even if R ¹ and R ² are the same between both substituted 5-membered ring ligands, both substituted ligands do not have a mirror image relationship with the entity. Another one of the asymmetric, even in relation entity and mirror image with respect to the position of the two substituents ligand substituents R ¹ and R ^2, R ¹ and at least one of R ² is both substituted five-membered ring coordinated It is not the same between children. Even in that case,
For example, even if the position of R ¹ is in a relationship between the entity and the mirror image, the two-substituted five-membered ring ligand is not in a relationship between the entity and the mirror image because of the different types. However, the asymmetric state in the present invention means only the former.

R ¹ has 1 to 6 carbon atoms as described above,
It is a monovalent hydrocarbon residue or a hydrocarbon residue containing silicon. More specifically, R ¹ is a saturated hydrocarbon group such as alkyl or cycloalkyl, an unsaturated hydrocarbon group such as alkenyl, or a silicon-containing hydrocarbon group such as alkylsilyl. Specific examples include methyl, ethyl, n-
Propyl, i-propyl, n-butyl, i-butyl, t
-Butyl, n-amyl, i-amyl, n-hexyl, cyclopropane, allyl, trimethylsilyl, dimethylethylsilyl and the like. Of these, methyl, ethyl, n-propyl, i-propyl, n
And alkyl groups such as -butyl, i-butyl and t-butyl.

R ² is more specifically a saturated hydrocarbon group such as alkylene or cycloalkylene, an unsaturated hydrocarbon group such as alkadienylene or arylene, or a silicon-containing hydrocarbon group such as alkylsilylalkylene or alkylsilylalkenylene. is there. Specific examples include butylene, methylbutylene, 2-methylbutylene, 1,2-dimethylbutylene, cyclopropylbutylene, 1,3-butadienylene, methyl-1,3-butadienylene, phenylbutylene, phenyl-1,3-butadienylene , Trimethylsilylbutylene, trimethylsilyl-1,3-
Examples thereof include butadienylene, dimethylethylsilylbutylene, and dimethylethylsilyl-1,3-butadienylene. Preferred among these are alkylene groups such as butylene and methylbutylene, 1,3-butadienylene,
It is an alkadienylene group such as methyl-1,3-butadienylene.

R ³ is more specifically a saturated hydrocarbon residue such as alkylene or cycloalkylene, an unsaturated hydrocarbon residue such as arylene, or a hydrocarbon residue containing silicon or germanium such as alkylsilylene or alkylgermylene. It is. Preferably, it is an alkylene, cycloalkylene, arylene, or alkylsilylene group.

X and Y are more specifically each independently hydrogen or halogen (eg, fluorine, chlorine,
Bromine, iodine, preferably chlorine), or 1-20 carbon atoms
A monovalent hydrocarbon residue or a hydrocarbon residue containing silicon or germanium (preferably those described above as R ¹ , particularly preferably methyl).

Representative synthetic route of compound [I] of the present invention
Is as follows. HR ^aIs

[0019]

Embedded imageIt shows. H₂R^a+ NC₄H₉Li → HR^aLi + nC₄H
₉ 2HR^aLi + R³Cl₂→ R³(HR^a)₂+ 2Li
Cl R³(HR^a)₂+ 2 · nC₄H₉Li → R³(R^a
Li)₂+ 2 · nC ₄H₉ R³(R^aLi)₂+ ZrCl₄→ R³(R^a)₂Zr
Cl₂+ 2LiCl

Non-limiting examples of the above transition metal compounds include the following. Although these compounds are simply referred to by their chemical names only, it goes without saying that the three-dimensional structure has the asymmetry referred to in the present invention. (1) ethylenebis- (2-methylindenyl) zirconium dichloride, (2) 1,1,2,2-tetraphenylethylenebis- (2-methylindenyl) zirconium dichloride, (3) dimethylsilylenebis -(2-
Methylindenyl) zirconium dichloride, (4) diphenylsilylene bis- (2-methylindenyl) zirconium dichloride, (5) dimethylgermylene bis-
(2-methylindenyl) zirconium dichloride,
(6) ethylene bis- (2-methyltetrahydroindenyl) zirconium dichloride, (7) 1,1,2,2
-Tetraphenyleneethylenebis- (2-methyltetrahydroindenyl) zirconium dichloride, (8) dimethylsilylenebis- (2-methyltetrahydroindenyl) zirconium dichloride, (9) diphenylsilylenebis- (2-methyltetrahydroindenyl) Zirconium dichloride, (10) dimethylgermylene bis-
(2-methyltetrahydroindenyl) zirconium dichloride,

(11) ethylene bis- (2-ethylindenyl) zirconium dichloride, (12) 1,1,2,2
-Tetraphenylethylenebis- (2-ethylindenyl) zirconium dichloride, (13) dimethylsilylenebis- (2-ethylindenyl) zirconium dichloride, (14) diphenylsilylenebis- (2-ethylindenyl) zirconium dichloride, (15) Ethylene bis- (2-ethyltetrahydroindenyl) zirconium dichloride, (16) ethylene bis- (2-n-propylindenyl) titanium dichloride, (17) ethylene bis- (2-methylindenyl) zirconium dimethyl ,
(18) 1,1,2,2-tetraphenylethylenebis-
(2-methylindenyl) zirconium dimethyl, (1
9) Dimethylsilylenebis- (2-methylindenyl)
Titanium dimethyl, (20) ethylene (2-methylindenyl) (2-ethylindenyl) zirconium dichloride,

(21) ethylene (2-methyltetrahydroindenyl) (2-ethyltetrahydroindenyl) zirconium dichloride, (22) ethylene bis- (2-trimethylsilylindenyl) zirconium dichloride,
(23) dimethylsilylenebis- (2-cyclopropyltetrahydroindenyl) hafnium dichloride, (24)
Ethylene bis- (2-methyl-4-methylindenyl)
Hafnium dichloride, (25) ethylenebis- (2-methyl-5-methylindenylzirconium dichloride,
(26) dimethylsilylenebis- (2-methylindenyl) zirconiummethyl (methylphenylamine),
(27) dimethylsilylenebis- (2-methylindenyl) zirconium butoxycyclolide, (28) dimethylsilylenebis- (2-methylindenyl) zirconium bis (trimethylsilyl), (29) dimethylsilylenebis- (2-methylindenyl) (Nyl) zirconium trimethylsilyl chloride and (30) dimethylsilylene bis- (2-methylindenyl) zirconium bis (trimethylsilyl) methyl chloride.

<Component (B)> Another component (component (B)) used in the present invention is represented by the following general formula [II]:
Or an alumoxane represented by [III].

[0024]

Embedded image (Here, m is a number of 4 to 30, preferably 10 to 25, and R ⁴ is a hydrocarbon residue, preferably 1 to 1 carbon atoms.
0, particularly preferably 1 to 4 carbon atoms. )

This component (B) is a product obtained by reacting one kind of trialkylaluminum or two or more kinds of trialkylaluminum with water. Specifically, (a) methylalumoxane, ethylalumoxane, propylalumoxane, butylalumoxane, isobutylalumoxane obtained from one kind of trialkylaluminum, and (ii) water obtained from two kinds of trialkylaluminum and water Such as methylethylalumoxane, methylbutylalumoxane and methylisobutylalumoxane. Among these, methylalumoxane is particularly preferred.

These alumoxanes can be used in combination of two or more in each group and between groups, and can be used in combination with other alkylaluminum compounds such as trimethylaluminum, triethylaluminum, triisobutylaluminum and dimethylaluminum chloride. It is also possible.

These alumoxanes can be prepared under various known conditions. Specifically, the following method can be exemplified. (A) a method in which a trialkylaluminum is directly reacted with water using an appropriate organic solvent such as toluene, benzene or ether; (b) a salt hydrate having a trialkylaluminum and water of crystallization such as copper sulfate or aluminum sulfate (C) a method of reacting trialkylaluminum with water impregnated in silica gel or the like; (d) a method of mixing trimethylaluminum and triisobutylaluminum to form an appropriate mixture such as toluene, benzene, or ether. A method of directly reacting with water using an organic solvent, (e) a method of mixing trimethylaluminum and triisobutylaluminum and reacting them with a salt hydrate having water of crystallization, for example, copper sulfate or aluminum sulfate hydrate,

(F) Impregnate silica gel or the like with water,
A method of treating with triisobutylaluminum, followed by an additional treatment with trimethylaluminum; (g) a method of synthesizing methylalumoxane and isobutylalumoxane by a known method, mixing predetermined amounts of these two components, and causing a heat reaction. (H) A salt having water of crystallization, such as copper sulfate pentahydrate, is added to an aromatic hydrocarbon solvent such as benzene or toluene.
A method of reacting with trimethylaluminum at a temperature of about 40 to 40 ° C. In this case, the amount of water used is usually 0.5 to 1.
5 The methylalumoxane thus obtained is a linear or cyclic organoaluminum polymer.

<Formation of Catalyst> The catalyst of the present invention is prepared by contacting the above-mentioned components (A) and (B) in a polymerization vessel or outside the polymerization vessel in the presence or absence of a monomer to be polymerized. Can be obtained.

The amounts of the components (A) and (B) used in the present invention are optional. For example, in the case of solvent polymerization,
Component (A) is used in an amount of 10 ⁻⁷ to 1 as a transition metal atom.
0 in the range of ² mmol / l is preferred. A molar ratio of Al / transition metal of 100 or more, particularly 1000 or more is preferably used.

The catalyst of the present invention comprises the components (A) and (B)
In addition to the above, it is possible to include other components as described above. However, as the third component (optional component) that can be added to the components (A) and (B), for example, H ₂ O,
Active hydrogen-containing compounds such as methanol, ethanol and butanol; electron-donating compounds such as ethers, esters and amines; and alkoxy-containing compounds such as phenyl borate, dimethylmethoxyaluminum, phenyl phosphite, tetraethoxysilane and diphenyldimethoxysilane. Examples can be given.

When using these catalyst systems for the polymerization of olefins, components (A) and (B) may be introduced separately into the reactor or may be precontacted with components (A) and (B). Those may be introduced into the reaction vessel.

<Use of Catalyst / Polymerization of Olefin> The catalyst of the present invention can be applied not only to solvent polymerization using a solvent but also to liquid phase solventless polymerization and gas phase polymerization substantially using no solvent. It is also applied to melt polymerization. It is applied to continuous polymerization and batch polymerization. As the solvent in the case of solvent polymerization, a saturated aliphatic or aromatic hydrocarbon such as hexane, heptane, pentane, cyclohexane, benzene, and toluene may be used alone or as a mixture.

The polymerization temperature is about -78 to 200 ° C, preferably -20 to 100 ° C. The olefin pressure of the reaction system is not particularly limited, but is preferably from normal pressure to 50 kg / cm.
^2- G range. In the polymerization, the molecular weight can be adjusted by known means, for example, selection of temperature and pressure or introduction of hydrogen.

An olefin polymerized by the catalyst of the present invention,
That is, the olefin used in the polymerization reaction in the method of the present invention is an α-olefin having 2 to 20 carbon atoms, preferably 2 to 10 carbon atoms.
It is an olefin. Specifically, for example, propylene,
-Butene, 4-methyl-1-pentene, 1-hexene,
There are 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and the like, particularly preferably propylene.
These α-olefins can be used as a mixture by mixing two or more kinds.

The catalyst of the present invention can also copolymerize the above α-olefins with ethylene. Further, other monomers copolymerizable with the above α-olefin, for example, conjugated and non-conjugated dienes such as butadiene, 1,4-hexadiene, 1,8-nonadiene, 1,9-decadiene, and the like, or And cyclopropane, cyclobutene, cyclohexene, norbornene and dicyclopentadiene.

[0037]

The following examples are provided to further illustrate the present invention. <Example 1> [Synthesis of ethylene bis-2-methylindenyl zirconium dichloride] All the reactions were performed in an inert gas atmosphere. The reaction solvent used was previously dried. In a 500 ml glass reaction vessel, 5.0 g (33 mmol) of 2-methylindene was dissolved in 80 ml of tetrahydrofuran and, under cooling, 1.6M of n-butyllithium.
21 ml of a hexane solution was slowly dropped into the reaction vessel. After stirring at room temperature for 1 hour, the mixture was cooled again, and 3.1 g of 1,2-dibromoethane was slowly added dropwise. After stirring at room temperature for 12 hours, 50 ml of water was added, and the organic phase was separated and dried. After washing several times with heptane and drying,
2.9 g of (2-methylindenyl) ethane were obtained.

2.1 g (7.3 mmol) of bis- (2-methylindenyl) ethane obtained by the above method was dissolved in 70 ml of tetrahydrofuran, and 9.2 ml of a 1.6 M solution of n-butyllithium in hexane was cooled. It was dripped slowly.
After stirring at room temperature for 3 hours, 1.6 g of zirconium tetrachloride
(7.0 mmol) / 60 ml of tetrahydrofuran solution was slowly added dropwise, and after stirring for 5 hours, hydrogen chloride gas was blown into the solution, followed by drying. Subsequently, soluble portions were separated by adding toluene and crystallized at a low temperature to obtain 0.95 g of yellow powder.

The compound obtained is ethylenebis- (2-methylindenyl) zirconium dichloride and both 2-methylindenyl groups are asymmetric, that is, the relationship between the entity and the mirror image with respect to the plane containing the zirconium atom. Was confirmed by ¹ HNMR.

[Synthesis of alumoxane] A toluene solution 56 containing 48.2 g of trimethylaluminum was placed in a reaction vessel.
5 g of copper sulfate pentahydrate (5 g) was charged into the vessel at 0 ° C. at intervals of 5 minutes in 5 g portions at 5 ° C. After the end, slowly 25
The temperature was raised to 25 ° C., and the reaction was performed at 25 ° C. for 2 hours and further at 35 ° C. for 2 days. The remaining copper sulfate solid was separated by filtration to obtain a toluene solution of alumoxane. The concentration of methylalumoxane is 27.3 mg / ml (2.7 w / v%)
Met.

[Polymerization] After sufficiently replacing the inside of a 1.5-liter stirred autoclave with propylene, 500 ml of sufficiently dehydrated and deoxygenated toluene was introduced, and methylalumoxane synthesized in Example 1 was replaced with an Al atom. 1 in conversion
After introducing 0 mmol and 1.0 mmol of ethylenebis- (2-methylindenyl) zirconium dichloride, propylene was introduced and polymerization was carried out at 20 ° C. for 15 minutes. Further, propylene is introduced and the internal pressure of the autoclave is 7 kg / cm ² -G
At 40 ° C. for 2 hours. After the completion of the reaction, the obtained polymer slurry was separated by filtration, and the polymer was dried. As a result, 56.2 g of a polymer was obtained.
The catalyst activity was 308 kg / g-Zr.h. The polymer had a number average molecular weight of 9.60 × 10 ⁴ , a molecular weight distribution of 2.02, and a melting point (DSC peak temperature) of about 134.
3 ° C.

<Comparative Example 1> Ethylene bis- (2-methyl)
Ruindenyl) zirconium dichloride
Using Tylene bis (indenyl) zirconium dichloride
The polymerization was carried out in the same manner as in Example 1 except that the polymerization was carried out. as a result,
80.9 g of polymer were obtained. Catalyst activity is 445kg
/ G · Zr · hr. The number average molecular weight of the polymer is
2.13 × 10 ⁴Has a molecular weight distribution of 2.04 and a melting point of about
135.2 ° C. This is extruded, injection molded
Shape was impossible.

<Comparative Example 2> The same procedure as in Example 1 was carried out except that ethylenebis (indenyl) hafnium dichloride was used instead of ethylenebis- (2-methylindenyl) zirconium dichloride. As a result, 12.1 g
Was obtained. The catalytic activity is 33.6 kg / g-H
At f · h, the number average molecular weight was 1.20 × 10 ⁵ , the molecular weight distribution was 2.63, and the melting point was 134.8 ° C.

<Example 2> The procedure of Example 1 was repeated, except that 5 ml of 1-hexene was added before introducing ethylene bis- (2-methylindenyl) zirconium dichloride. As a result, 51.2 g of a polymer was obtained. The catalyst activity was 281 kg / g-Zr.h. The polymer has a number average molecular weight of 7.89 × 10 ⁴ , a molecular weight distribution of 1.90, and a hexene content of 0.59 mol in the polymer.
%, Melting point 131.4 ° C.

[0045]

As described above, according to the present invention, it is possible to produce a stereoregular polyolefin having a high molecular weight in a high yield in the section of "Means for Solving the Problems".

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Eiji Uchino 1-Tohocho, Yokkaichi-shi, Mie F-term in Yokkaichi Research Institute, Mitsubishi Petrochemical Co., Ltd. BC25B EA01 EB04 FA02 GA01 GA12 GB01

Claims (6)

[Claims] 1. A method for producing a propylene polymer using an olefin polymerization catalyst comprising the following components (A) and (B). Component (A): a transition metal compound represented by the following general formula [I]: (Wherein, M is a transition metal selected from the group consisting of titanium, zirconium and hafnium;
¹ may be the same or different and have 1 to 6 carbon atoms;
A monovalent hydrocarbon residue or a silicon-containing hydrocarbon residue, wherein two R ^{2 's} may be the same or different, and are attached to two adjacent carbon atoms of a five-membered ring ligand; A divalent hydrocarbon residue having 4 to 20 carbon atoms or a silicon-containing hydrocarbon residue, wherein R ³ has 1 to 30 carbon atoms;
Is a divalent hydrocarbon residue or a hydrocarbon residue containing silicon or germanium, wherein X and Y are each independently hydrogen or halogen, or C 1-2
0 is a monovalent hydrocarbon residue or a hydrocarbon residue containing nitrogen, oxygen or silicon. Provided that the substituent R ¹
And the two five-membered ring ligands having R ² are asymmetric with respect to the plane containing M in terms of their relative positions via the group R ³ . ) Component (B) An alumoxane represented by the following general formula [II] or [III]. Embedded image (Where m is a number from 4 to 30, and R ⁴ represents a monovalent hydrocarbon residue) 2. The process for producing a propylene-based polymer according to claim 1, wherein a transition metal compound in which R ² is methyl-1,3-butadienylene or phenyl-1,3-butadienylene is used. 3. M is zirconium and R ² is methyl-1,3.
The method for producing a propylene-based polymer according to claim 1, wherein a transition metal compound that is butadienylene is used. 4. M is hafnium, R ² is methyl-1,3-
The method for producing a propylene-based polymer according to claim 1, wherein the method is butadienylene. 5. M is zirconium, R ² is phenyl-1,
The method for producing a propylene-based polymer according to claim 1, wherein a transition metal compound that is 3-butadienylene is used. 6. M is hafnium and R ² is phenyl-1,3.
The method for producing a propylene-based polymer according to claim 1, wherein a transition metal compound that is butadienylene is used.