JPH05287017A - Olefin polymerization catalyst and production of polyolefin using the same - Google Patents

Abstract

PURPOSE:To improve catalytic activity by reacting a specific transition metal compound with an organometallic compound and bringing the reaction product into contact with a compound which terns into a stable anion by reaction with the reaction product. CONSTITUTION:An organometallic compound is reacted at -20 to 100 deg.C with a transition metal compound represented by formula I, II, or III (wherein Cp is an unsaturated hydrocarbon residue coordinated to M; the groups of Cp' are the same or different unsaturated hydrocarbon residues crosslinked by R; R is a divalent residue containing N, O, Si, P, or S, a linear saturated hydrocarbon residue which may have a side chain, or a linear saturated hydrocarbon residue in which the backbone carbon atoms have been partly or wholly replaced by Si, Ge, or Sn; M is a metal atom of Groups III to V of the periodic table; and X is a ligand coordinated to M and containing N, O, Si, P, or B). This reaction product is brought into contact with a compound which turns into a stable anion by reaction with the reaction product to thereby obtain the title catalyst.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an olefin polymerization catalyst and a method for producing a polyolefin using the same. Specifically, it relates to a method for producing a polyolefin with high activity by using an olefin polymerization catalyst in which a specific compound is combined.

[0002]

BACKGROUND OF THE INVENTION As a polymerization catalyst for olefins, a combination of a metallocene compound having a group having a conjugated π electron, particularly cyclopentadiene and its derivative as a ligand, and an alkylaluminoxane obtained by the reaction of trialkylaluminum and water. It has been known. For example, JP-A-58-19309 discloses a method for polymerizing biscyclopentadienyl zirconium dichloride and olefin using methylaluminoxane as a catalyst. In addition, JP-A-61-130
314, JP-A-61-264010, JP-A-1-301704 and JP-A-301704
2-41303 discloses a method for producing isotactic poly-α-olefins or syndiotactic poly-α-olefins and a polymerization catalyst for producing these stereoregular poly-α-olefins, All of the disclosed catalyst systems use aluminoxane as a cocatalyst.

On the other hand, research on homogeneous Ziegler-Natta catalysts that do not use aluminoxane has also been conducted,
A catalyst system mainly composed of a metallocene compound and an alkylaluminum compound has been investigated. Although this catalyst system has low activity, it is already known to have polymerization activity for olefins. It is considered that the active species of this catalyst is a cationic metallocene compound or an ion pair type metallocene complex.

Recently, it has been reported that an isolated cationic metallocene compound having cyclopentadiene or a derivative thereof as a ligand has a polymerization activity for an olefin by itself, even in the absence of coexisting methylaluminoxane. Has been done. For example, RF JORDAN et al., J. Am. Chem. Soc., 1986, Vol. 108, page 7410-7411, has tetraphenylborane as an anion, and has a zirconium cation having two cyclopentadienyl groups and a methyl group as ligands. It has been reported that the complex was isolated by using a donor such as tetrahydrofuran as a ligand, and the isolated complex had a polymerization activity of ethylene in methylene chloride.

Turner et al., J. Am. Chem. Soc., 1989
Volume 111, pages 2728-2729 and special table 1-501950, special table 1-5020
A transition metal compound having a cyclopentadienyl group having a substituent in 36 or a derivative thereof as a ligand and capable of reacting with at least one proton, and a compound providing a stable anion having a cation capable of giving a proton. It has been reported that the ion-pair type metallocene complex formed from OH has the polymerization activity of olefin. Further, JP-A-3-139504, JP-A-3-179005, JP-A-3-179006,
JP-A-3-207703 and JP-A-3-207704 also disclose olefin polymerization methods that do not use aluminoxane.

Further, Zambelli et al., Macromolecules, 1989.
Vol. 22, pp. 2186-2189, pp. 2186-2189, shows that isotactic polypropylene can be obtained by polymerizing propylene with a catalyst that combines a zirconium compound having a cyclopentadienyl group derivative as a ligand and trimethylaluminum and fluorodimethylaluminum. It has been reported, and in this case also, the active species is considered to be an ion pair type metallocene compound.

[0007]

The method for polymerizing olefins using a combination catalyst of a metallocene compound and an alkylaluminoxane is characterized by high polymerization activity per transition metal. However, in these methods, the polymerization activity per metallocene compound unit is high because a large amount of expensive aluminoxane is used as a cocatalyst, and the activity per aluminoxane unit is not so high. Therefore, there is a problem that the production cost of the polymer becomes high, and it is very difficult to remove the aluminoxane from the polymer produced after the polymerization, and there is a problem that a large amount of catalyst residue remains in the polymer.

[0008] On the other hand, in the method in which a cationic zirconium complex is used as a catalyst without using an alkylaluminoxane, the above-mentioned problems relating to the alkylaluminoxane are eliminated, but these catalyst systems are different from olefins in comparison with the catalyst system using an alkylaluminoxane. There was a problem that the polymerization activity of was very small. Furthermore, in these methods, it is necessary to use a dimethyl complex or the like obtained by alkylating a dichloro complex with an expensive alkylating reagent such as methyllithium or methyl Grignard reagent, and there is a problem in the yield of alkylation. Therefore, there is a problem that the production cost of the catalyst increases. Further, many of these alkylated metallocene compounds are unstable, and particularly in a solution dissolved in a hydrocarbon solvent or the like, they are easily decomposed by a trace amount of impurities such as water and oxygen, or light, so that the monomer or the monomer during polymerization may be easily decomposed. The impurities contained in the solvent should be minimized.

When olefins are polymerized using a Ziegler type catalyst, it is possible to remove impurities contained therein by treating the monomer and / or the solvent with an organometallic compound, particularly an alkylaluminum compound. .. This method can be applied to the case of using these ion pair catalysts, using a monomer and / or a solvent treated with alkylaluminum, a transition metal compound, and a compound that donates a stable anion having a cation. After forming the ion pair type metallocene complex to be formed, and removing the influence of impurities by adding an organometallic compound, the polymerization activity for olefins can be improved to some extent even with these catalysts JP-A-3-179005, It is shown in JP-A-3-207704. However, even such a method is inferior in activity as compared with the combined catalyst system using an alkylaluminoxane as a cocatalyst.
Transition metals that are relatively stable, inexpensive, and easy to synthesize
It has been desired that the transition metal compound having a heteroatom bond can be used as it is and the polymerization of olefin can be made highly active.

[0010]

[Means for Solving the Problems] The present inventors have completed the present invention by solving the above problems and earnestly studying a method for producing a polyolefin with high activity using a specific transition metal compound.

That is, the present invention is represented by the following chemical formula 7, chemical formula 8 or chemical formula 9 (in the formula, Cp is an unsaturated hydrocarbon residue coordinated to M, and Cp 'is the same as R crosslinked with each other. Or a different unsaturated hydrocarbon residue coordinated to M is replaced by R
Is a linear saturated hydrocarbon residue which may have a divalent nitrogen atom, oxygen atom, silicon atom, phosphorus atom or sulfur atom or a side chain, or a part of the linear carbon atom thereof, or Residues all substituted with silicon atoms, germanium atoms or tin atoms, M is a metal atom selected from Group 3, 4 or 5 of the Periodic Table, and X is coordinated with M. A transition metal compound represented by a ligand containing a nitrogen atom, an oxygen atom, a silicon atom, a phosphorus atom, a boron atom or a sulfur atom).

[0012]

[Chemical formula 7] CpMXn

[0013]

[Chemical 8]

[0014]

[Chemical 9] An olefin polymerization catalyst obtained by reacting with a reaction product of a transition metal compound and an organometallic compound after being reacted with an organometallic compound and contact-treated with a compound that becomes a stable anion,
Further, the present invention is a method for producing a polyolefin using the above catalyst.

In the present invention, the transition metal compound is
Examples thereof include transition metal compounds represented by Chemical Formula 7, Chemical Formula 8 or Chemical Formula 9 of the above general formula.

In the formula, as the unsaturated hydrocarbon residue represented by Cp, a hydrocarbon having a monocyclic or polycyclic conjugated π electron having 5 to 50 carbon atoms or some of them are heteroatoms. Examples thereof include a residue substituted with, and specifically, cyclopentadienyl or a part or all of hydrogen thereof substituted with a hydrocarbon residue having 1 to 10 carbon atoms (here, a hydrocarbon residue). May have a structure in which its terminal is again bound to the cyclopentadiene ring, or may be a residue in which a part of the carbon atoms of a hydrocarbon residue is replaced with a hetero atom), or indenyl, fluorenyl, etc. Ring aromatic hydrocarbon residue or some or all of the hydrogen thereof is replaced by a hydrocarbon residue having 1 to 10 carbon atoms (wherein the hydrocarbon residue has its end bound to the aromatic ring again) did May be a concrete, also ligands some of the carbon atoms of the hydrocarbon residue is coordinated to the transition metal atom M, etc. may also be) at residue substituted with heteroatoms are exemplified. In the case of the chemical formula 8 in the above general formula, these may be the same as or different from each other.

The unsaturated hydrocarbon residue represented by Cp 'is a monocyclic or polycyclic conjugated π having 5 to 50 carbon atoms.
Examples include hydrocarbons having electrons or residues in which some of them are substituted with heteroatoms. Specifically, cyclopentadienyl or a part or all of hydrogens thereof is a carbon atom having 1 to 10 carbon atoms. Substituted with a hydrogen residue (wherein the hydrocarbon residue may have a structure in which its end is again bound to the cyclopentadiene ring, and some of the carbon atoms of the hydrocarbon residue are replaced with heteroatoms) Or a polycyclic aromatic hydrocarbon residue such as indenyl or fluorenyl or a part or all of the hydrogen thereof is replaced by a hydrocarbon residue having 1 to 10 carbon atoms (wherein The hydrocarbon residue may have a structure in which the end is again bound to the aromatic ring, or may be a residue in which a part of carbon atoms of the hydrocarbon residue is replaced with a hetero atom). The ligand coordinated to the atom M is exemplified. These may be the same or different from each other,
Two Cp's have a structure bridged by R.

The divalent group represented by R includes -O- and -S-.
, -SS-, -SO-, -SO _2- , -CO-, -NR-, -PR-, -POR-
, -OSiR ₂ O- or a methylene group represented by the following formula 10 or a part or all of the carbon atoms of the methylene group is substituted with a silicon atom, a germanium atom, or a tin atom, a silylene group, a germylene group, or stannylene. The base is exemplified.

[0019]

Embedded image _{- (R 2 C) k- (} R 2 Si) l - (R 2 Ge) p - (R 2 Sn) q - ( hydrocarbons to R is not hydrogen or C 1 -C formula 20 Representing a residue, each R may be the same or different, k, l, p and q are integers from 0 to 4 and the following formula 1
Represents an integer that satisfies ≦ k + l + p + q ≦ 4. )

X is a ligand containing a nitrogen atom, an oxygen atom, a silicon atom, a phosphorus atom, a boron atom or a sulfur atom coordinated to M, and is NR ' ₂ , OR', OCR ' ₂ , OSiR' ₃ , SiR. ' ₃ , GeR' ₃ , P
_{R '2, POR' 2,} SR ', SOR', SO 2 R ', BR' 3 (R ' is the residual of some hydrocarbons or of their 20 number of 1 hydrogen or carbon has been replaced with a heteroatom Group). n is 1, 2 or 3 depending on the valence of M. n is 2
In the above cases, X may be cross-linked with each other, and a chelate type ligand is also exemplified.

The compound which reacts with the reaction product of the transition metal compound and the organometallic compound to form a stable anion is an ionic compound or an electrophilic compound formed from an ion pair of a cation and an anion. It reacts with a reaction product of a metal compound and an organometallic compound to form a polymerization active species. Among these, the ionic compound is represented by the following chemical formula 11.

[0022]

[Of 11] [Q] m [Y] m -

In the formula, Q is a cation component of an ionic compound, and is a carbonium cation, tropylium cation, ammonium cation, oxonium cation, sulfonium cation, phosphonium cation, transition metal cation, ferrocenium cation. , Indenium cations, and the like. Specific examples of these cations include triphenylcarbonium, diphenylcarbonium, cycloheptatrienium, tributylammonium, N, N-dimethylanilinium, dipropylammonium, dicyclohexylammonium, triphenylphosphonium, trimethylphosphonium and triphenyl. Examples include cations such as sulfonium, triphenyloxonium, triethyloxonium, pyrylium, silver and ferrocenium.

Y is an anion component of an ionic compound, and examples thereof include a boron compound anion, an aluminum compound anion and a gallium compound anion. Specifically, tetraphenylboron, tetrakis (pentafluorophenyl) boron, tetrakis (3,4,5-trifluorophenyl) boron, tetraphenylaluminum,
Tetrakis (pentafluorophenyl) aluminum,
Examples include anions such as tetrakis (3,5-bistrifluorophenyl) aluminum, tetraphenylgallium, and tetrakis (pentafluorophenyl) gallium.

The electrophilic compound, which is known as a Lewis acid compound, is a compound which reacts with a reaction product of a transition metal compound and an organometallic compound to form a polymerization active species. Examples thereof include compounds and metal oxides known as solid acids. Specific examples include magnesium halides, manganese halides, inorganic oxides such as alumina, silica-alumina and magnesium silicate, and oxides forming an intercalation compound such as smectite.

Since many of these inorganic oxides are usually insoluble in organic solvents, those having a large surface area are preferable.
Small ones or further ground surface area, it is preferable to use a compound of a time 5 m ² / g to inorganic oxides 800 m ² / g as synthesized and the specific surface area by a method such as to re-precipitated after dissolution.

The organometallic compound which is reacted with the transition metal compound in the present invention includes metal atoms of Groups 1, 2, 12 and 13 of the Periodic Table, preferably aluminum, boron, gallium, zinc or magnesium. , A halogen atom, an oxygen atom or a hydrogen atom or a residue such as alkyl, alkoxy or aryl is coordinated to these metals, and when there are a plurality of ligands, they may be the same or different. However, at least one of them is an alkyl group. For example, an alkyl metal compound having 1 or 2 or more alkyl residues having 1 to 12 carbon atoms, an alkyl metal halide having the above alkyl residue and another atom or residue coordinated, an alkyl metal alkoxide, etc. It is illustrated. Among them, an alkylboron compound or an alkylaluminum compound in which at least one alkyl residue having 2 or more carbon atoms is coordinated is preferably used.

Examples of preferred organometallic compounds for which the metal atom is aluminum include trimethyl aluminum, triethyl aluminum, tri-n-propyl aluminum, triisopropyl aluminum, tributyl aluminum, triisobutyl aluminum, tripentyl aluminum, trihexyl aluminum. ,
Triheptyl aluminum, trioctyl aluminum, tridecyl aluminum, isoprenyl aluminum, diethyl aluminum hydride, diisopropyl aluminum hydride, diisobutyl aluminum hydride, diethyl aluminum chloride, di-n-propyl aluminum chloride, diisopropyl aluminum chloride, diisobutyl aluminum chloride, diethyl aluminum Ethoxide, diisopropyl aluminum isopropoxide, ethyl aluminum sesquichloride, isopropyl aluminum sesquichloride, isobutyl aluminum sesquichloride, ethyl aluminum dichloride, isopropyl aluminum dichloride, isobutyl aluminum dichloride, ethyl acetate Mini Umm diisopropoxide, and the like.

The method for reacting the transition metal compound with the organometallic compound is not particularly limited, and the two may be simply mixed. Usually, the transition metal compound is a solid, and the organic metal compound is liquid or solid in many cases, and therefore it is preferable to treat the compound in a hydrocarbon solvent. Examples of the hydrocarbon solvent include propane, butane, isobutane, pentane, hexane, heptane, octane, nonane, decane, cyclopentane, cyclohexane, cycloheptane, methylcyclohexane and other saturated hydrocarbon compounds, benzene, toluene, xylene, etc. Aromatic hydrocarbon compounds are exemplified.

The nature of the reaction product produced in this reaction has not been clarified so far, and the structure of the reaction product has not been clarified. However, unlike the alkylmetallocene compound, when it is used as a polymerization catalyst for olefins, It becomes a very highly active species.

The ratio of the organometallic compound used to the transition metal compound is 1 to 100,000 mole times, usually 1 to 5000 mole times. The treatment temperature is not particularly limited, but usually -20
It is preferable to carry out at a temperature of -100 ° C. The temperature at which these mixtures are stored is not particularly limited, but it is also preferable to store at a temperature of −20 to 100 ° C. The treatment time is not particularly limited, and when both are a solution, it may be at the point of time when they are uniformly mixed, and when insolubles are present, they can be used at any time after they have been dissolved in the solvent. Of course, as described above, it is possible to store it as it is until use and use it as needed. Further, the concentration of the reactant in the hydrocarbon solvent is stable even at a considerably high concentration as described above, and therefore it is not particularly limited, but it is usually 10 ^-7 to 1 mol / liter, preferably a molar concentration based on the metallocene compound. Is 10 ^{−5 to} 0.1 mol / liter.

The amount of the above compound forming a stable anion used is 0.1 with respect to the transition metal compound used in the catalyst.
〜100,000 mole times, usually 0.5〜10000 mole times.

An important point in the present invention is that the transition metal compound is first reacted with the organometallic compound, and then the compounds forming these stable ions are contacted. If this order is different, the olefin will not polymerize at all,
Even if polymerized, the activity becomes very low and the reproducibility of polymerization is poor.

Further, a compound obtained by reacting a transition metal compound with an organometallic compound to form a stable anion by reacting with the reaction product (hereinafter referred to as a stable anion compound)
Contacting with an olefin prior to contacting with is a preferred embodiment of the invention. Polymerization proceeds smoothly by using a catalyst system that is contacted with an olefin and then with a stable anion compound,
Also, the polymerization activity is improved.

When the reaction product obtained by reacting the transition metal compound with the organometallic compound and the stable anion compound are brought into contact with each other, the total amount of the compound serving as the stable anion is not added all at once, but at least twice or more. It can also be divided and added. That is, one part of the stable anion compound is added before the polymerization is started to start the polymerization, and the remaining amount is further added at an appropriate interval during the reaction or continuously added. is there. By doing so, it becomes possible to carry out the polymerization stably for a long time.

Further, in the present invention, hydrogen which is usually used in a Ziegler type catalyst for adjusting the molecular weight of the obtained polyolefin can be used. Furthermore, the presence of an internal olefin in the polymerization of the olefin can control the molecular weight of the produced polyolefin.

Specific examples of the internal olefin include 2-
Straight chain internal olefins such as butene, 2-pentene and 2-hexene, cyclic olefins such as cyclopentene, cyclohexene, cycloheptene and norbornene, 5-methylene-2-
Examples include dienes such as norbornene and 5-ethylidene norbornene.

Examples of the solvent utilized in the preparation, polymerization or treatment of the catalyst using the catalyst component in the present invention include propane, butane, isobutane, pentane, hexane, heptane, octane, nonane, decane, cyclopentane, cyclohexane, Saturated hydrocarbon compounds such as cycloheptane and methylcyclohexane, aromatic hydrocarbon compounds such as benzene, toluene and xylene, and halogenated hydrocarbon compounds such as methylene chloride and chlorobenzene can also be used. Further, an ether, a nitrile, an ester compound or the like can be used as long as the solvent itself does not bind to the produced transition metal cation compound or strongly coordinate to inactivate the polymerization activity. The olefin polymerization conditions using this catalyst component are not particularly limited, and a solvent polymerization method using an inert medium, a bulk polymerization method substantially free of an inert medium, or a gas phase polymerization method can also be used.

Examples of the olefin used for the polymerization include olefins having 2 to 25 carbon atoms, specifically, ethylene, propylene, butene-1, pentene-1, and hexene-.
1, heptene-1, octene-1, nonene-1, decene-1, undecene-1, dodecene-1, tridecene-1, tetradecene
-1, pentadecene-1, hexadecene-1, octadecene-1
In addition to linear olefins such as 3-methylbutene-1,4-methylpentene-1,4,4-dimethylpentene-1 and other branched olefins and cyclopentene, cyclooctene, norbornene and other cyclic olefins are exemplified. The olefins can be homopolymerized or copolymerized with each other, and if necessary, the diene can be copolymerized. Furthermore, in this polymerization system, an aromatic olefin such as styrene can be polymerized, and an aromatic olefin alone or a copolymer with the above-mentioned olefin can be also used.

As the polymerization temperature and the polymerization pressure, general conditions used in a known method are used. The polymerization temperature can be -20 to 150 ° C. and the polymerization pressure can be atmospheric pressure to 100 kg / cm ^2. ..

[0041]

EXAMPLES The present invention will be further described with reference to the following examples.

Example 1 An autoclave having a volume of 2 liters was charged with 1 liter of toluene, and then propylene was added until the pressure reached 2 kg / cm ² · G, and then depressurization was repeated 3 times to replace toluene with propylene. did. Dissolve 10 mg of dicyclopentadienyl zirconium dimethoxide in 20 ml of toluene,
To this, 0.33 g of triethylaluminum was added and mixed, charged into the above autoclave, propylene was added so as to be 3 kg / cm ² · G at 20 ° C, and then 65 mg of triphenylmethanetetra (pentafluorophenyl) boron was added. What was melt | dissolved in 20 ml of toluene was press-fitted, and it introduce | transduced propylene and superposed | polymerized at 20 degreeC and 3 kg / cm < ² > * G for 1 hour.

After the polymerization, propylene was purged, and the content was filtered and dried to obtain 10.1 g of a polymer. The amount of polypropylene produced per 1 g of zirconium in the catalyst was 3.1 kg. The intrinsic viscosity (hereinafter referred to as η) of the polymer measured with a 135 ° C. tetralin solution was 0.31, and the polymer had an atactic structure according to ¹³ C-NMR.

Comparative Example 1 Example 1 without the use of triisobutylaluminum
Polymerization of propylene was carried out in the same manner as, but no polymer was obtained.

Example 2 Ethylene was used instead of propylene and the polymerization pressure was 8 kg.
Polymerization of ethylene was carried out in the same manner as in Example 1 except that the value was / cm ² · G, and 57 g of a polymer was obtained. The amount of polyethylene produced per 1 g of zirconium in the catalyst was 177 kg.

Comparative Example 2 Example 2 without the use of triisobutylaluminum
Polymerization of ethylene was carried out in the same manner as, but no polymer was obtained.

Example 3 Propylene was polymerized in the same manner as in Example 1 except that dicyclopentadienyl zirconium ditosylate was used instead of dicyclopentadienyl zirconium dimethoxide, and 11.6 g of a polymer was obtained. Obtained. η was 0.44, and the polymer had an atactic structure according to ¹³ C-NMR.

Example 4 Triphenylmethane tetra (pentafluorophenyl)
Polymerization of propylene was carried out in the same manner as in Example 1 except that triphenylmethanetetra (pentafluorophenyl) aluminum was used instead of boron to obtain 12.2 g of atactic polypropylene.

[0049]

Industrial Applicability By carrying out the method of the present invention, a polyolefin having a high activity per catalyst can be obtained using an inexpensive catalyst, which is industrially valuable.

[Brief description of drawings]

FIG. 1 is a flow chart for facilitating understanding of the present invention.

Claims (2)

[Claims] 1. A chemical formula 1, chemical formula 2, or chemical formula 3 of the following general formula (wherein Cp is an unsaturated hydrocarbon residue coordinated to M, Cp '
Is an unsaturated hydrocarbon residue, which is the same or different from each other and is coordinated to M, which is bridged with R, R is a divalent nitrogen atom,
A residue containing an oxygen atom, a silicon atom, a phosphorus atom, or a sulfur atom, or a linear saturated hydrocarbon residue which may have a side chain, or a part or all of the linear carbon atoms thereof is a silicon atom or a germanium atom. Or a residue substituted with a tin atom, M is a metal atom selected from Group 3, 4 or 5 of the periodic table, and X is a nitrogen atom, oxygen atom or silicon coordinated to M. Atom, phosphorus atom, boron atom, or sulfur atom-containing transition metal compound represented by the formula: CpMXn [Chemical 3] An olefin polymerization catalyst obtained by reacting with an organometallic compound and then contact-treated with a compound that reacts with a reaction product of the transition metal compound and the organometallic compound to form a stable anion. 2. Chemical formula 4, chemical formula 5 or chemical formula 6 of the following general formula (wherein Cp is an unsaturated hydrocarbon residue coordinated to M, Cp '
Is an unsaturated hydrocarbon residue, which is the same or different from each other and is coordinated to M, which is bridged with R, R is a divalent nitrogen atom,
A residue containing an oxygen atom, a silicon atom, a phosphorus atom, or a sulfur atom, or a linear saturated hydrocarbon residue which may have a side chain, or a part or all of the linear carbon atoms thereof is a silicon atom or a germanium atom. Or a residue substituted with a tin atom, M is a metal atom selected from Group 3, 4 or 5 of the periodic table, and X is a nitrogen atom, oxygen atom or silicon coordinated to M. Atom, a phosphorus atom, a boron atom or a sulfur atom-containing transition metal compound represented by the formula: CpMXn [Chemical 6] Characterized in that an olefin is polymerized by using an olefin polymerization catalyst obtained by reacting with a reaction product of a transition metal compound and an organometallic compound and reacting with a compound which becomes a stable anion after being reacted with an organometallic compound. A method for producing a polyolefin.