JP7579672B2 - Catalyst for olefin polymerization and method for producing olefin polymer - Google Patents

Description

The present invention relates to an olefin polymerization catalyst and a method for producing an olefin polymer using the olefin polymerization catalyst.

By blending carbon materials such as graphite, graphene, and carbon nanotubes (CNTs) with polyolefins, it is possible to impart high thermal conductivity, electrical conductivity, and weather resistance to the polyolefins (see, for example, Patent Document 1). However, there is a problem in that it is difficult to disperse these carbon materials in polyolefins.

In order to improve the dispersibility of carbon materials in polyolefins, a method has been proposed for producing a composite of carbon materials and polyolefins by polymerization using a polymerization catalyst in which a metal complex is supported or impregnated on the carbon material (see, for example, Patent Documents 2 to 4). However, all of these methods use expensive organoaluminum oxy compounds such as methylaluminoxane (MAO) as co-catalysts, and there is a demand for reducing production costs.

JP 2017-071079 A JP 2006-176601 A JP 2007-161741 A Special Publication No. 2005-506404

The objective of the present invention is to provide an olefin polymerization catalyst that exhibits high polymerization activity without the use of expensive organoaluminum oxy compounds and that can produce olefin polymers in which carbon materials are efficiently dispersed, and a method for producing olefin polymers using the olefin polymerization catalyst.

The present inventors conducted extensive research to solve the above problems. As a result, they discovered that the above problems could be solved by using a specific carbon material and a specific organoaluminum compound as co-catalysts, and thus completed the present invention.

That is, the olefin polymerization catalyst according to the present invention is
A carbon material (A) that satisfies the following requirements (AI) and (A-II);
An organoaluminum compound (B) represented by the following general formula (BI),
and a transition metal compound (C) represented by the following general formula (CI):
(A-I) The nitrogen atom/carbon atom molar ratio measured by X-ray photoelectron spectroscopy (XPS) is 0.003 or more and 0.300 or less;
(A-II) A nitrogen-doped carbon material having a graphene structure in which nitrogen atoms are substituted or introduced;
R ^a _m Al(OR ^b ) _n H _p X _q ...(BI)
[In general formula (B-I), R ^a and R ^b represent a hydrocarbon group having 1 to 15 carbon atoms and may be the same or different, X represents a halogen atom, m represents an integer of 1 to 3, n represents an integer of 0 to 2, p represents an integer of 0 to 2, q represents an integer of 0 to 2, and m+n+p+q=3.]
L _m MX _n ... (C-I)
[In formula (C-I), M is an atom selected from the group consisting of atoms of Groups 3, 4, 5, 6, 7, 8, 9, 10, and 11 of the periodic table, and lanthanide atoms;
L is a ligand, and a plurality of L may be the same or different from each other, and a plurality of L may be connected by a substituent in L, but at least one L contains at least one atom selected from the group consisting of boron, nitrogen, oxygen, phosphorus, sulfur and selenium,
m is an integer of 2 or more,
n is an integer of 1 to 4 that satisfies the valence of M;
X is a leaving group selected from a hydrogen atom, a halogen atom, a hydrocarbon group, a halogen-containing group, a silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a phosphorus-containing group, a boron-containing group, an aluminum-containing group, a conjugated diene derivative group, and a neutral ligand capable of coordinating with a lone electron pair, and when n is 2 or more, multiple Xs may be the same or different from each other and may be bonded to each other to form a ring.

The present invention provides an olefin polymerization catalyst that exhibits high polymerization activity without using expensive organoaluminum oxy compounds and can produce olefin polymers in which carbon materials are efficiently dispersed, and a method for producing olefin polymers using the olefin polymerization catalyst.

FIG. 2 is a schematic diagram showing an example of the configuration of an in-liquid plasma generating device used in the production of carbon material (A).

The present invention will be described in detail below.
[Olefin polymerization catalyst]
The olefin polymerization catalyst of the present invention comprises
A carbon material (A) that satisfies the following requirements (AI) and (A-II);
An organoaluminum compound (B) represented by the following general formula (BI),
and a transition metal compound (C) represented by the following general formula (CI):

(AI) The nitrogen atom/carbon atom molar ratio measured by X-ray photoelectron spectroscopy (XPS) is 0.003 or more and 0.300 or less.
(A-II) Nitrogen-doped carbon material having a graphene structure in which nitrogen atoms are substituted or introduced.

R ^a _m Al(OR ^b ) _n H _p X _q ...(BI)
In the general formula (BI), R ^a and R ^b each represent a hydrocarbon group having 1 to 15 carbon atoms and may be the same or different from each other; X represents a halogen atom; m represents 1 or more; 3 or less, n is an integer between 0 and 2, p is an integer between 0 and 2, q is an integer between 0 and 2, and m+n+p+q=3.

L _m MX _n ...(C-I)
In the general formula (CI), M is an atom of Group 3, 4, 5, 6, 7, 8, 9, 10, or 11 of the periodic table. and a lanthanide atom, L is a ligand, and a plurality of L may be the same or different, and a plurality of L may be connected by a substituent in L At least one L contains at least one atom selected from the group consisting of boron, nitrogen, oxygen, phosphorus, sulfur and selenium, and m is 2 or more. n is an integer of 1 to 4 satisfying the valence of M; X is a leaving group, which is a hydrogen atom, a halogen atom, a hydrocarbon group, a halogen-containing group, a silicon-containing group, a group selected from the group consisting of an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a phosphorus-containing group, a boron-containing group, an aluminum-containing group, a conjugated diene derivative group, and a neutral ligand capable of coordinating with a lone electron pair; When n is 2 or more, a plurality of X's may be the same or different and may be bonded to each other to form a ring.

Each component constituting the olefin polymerization catalyst of the present invention will be described below.
<Carbon material (A)>
The carbon material (A) used in the present invention satisfies the following requirements (AI) and (A-II).

(A-I) The nitrogen atom/carbon atom molar ratio measured by X-ray photoelectron spectroscopy (XPS) is 0.003 or more and 0.300 or less, preferably 0.004 or more and 0.200 or less, and more preferably 0.005 or more and 0.100 or less.

The nitrogen atom/carbon atom molar ratio is a value obtained by X-ray photoelectron spectroscopy (XPS) measurement, and specifically, the nitrogen atom/carbon atom molar ratio is obtained by calculating from the peak intensities of nitrogen atoms and carbon atoms in the spectrum obtained from the carbon material (A).

A higher nitrogen atom/carbon atom molar ratio is preferable because it promotes coordination with the cation generated from the transition metal compound (C) described below. However, if the nitrogen atom/carbon atom molar ratio is too high, the graphene structure in the carbon material (A) tends to decrease.

(A-II) Nitrogen-doped carbon material having a graphene structure in which nitrogen atoms are substituted or introduced.
The nitrogen-doped carbon material is a material in which nitrogen atoms are introduced into a carbon material, and typically has a structure in which nitrogen atoms are doped (substituted or introduced) at the positions of carbon atoms in a graphene structure. The carbon material (A) preferably contains this nitrogen-doped carbon material on at least a part of the surface of the carbon material.

The carbon material other than the nitrogen-doped carbon material in the carbon material (A) used in the present invention, and the carbon material to which nitrogen atoms are doped in the nitrogen-doped carbon material, can be used without any particular limitation as long as it has a graphene structure in at least a part of its structure. Such a carbon material may be either a carbonaceous material with relatively low crystallinity or a graphitic material with relatively high crystallinity. Examples include graphene, graphene flakes in which 1 to 10 sheets of graphene are stacked by van der Waals forces, graphite with more stacks than graphene flakes, carbon nanotubes in which sheet-like graphene is rolled into a cylindrical shape, onion-like carbon in which multiple graphene sheets are closed in a concentric shell shape, carbon nanoscrolls in which sheet-like graphene is rolled into a spiral shape, carbon nanohorns in which sheet-like graphene is rolled into a horn shape, carbon nanocones in which sheet-like graphene is rolled into a cone shape, carbon nanowalls in which sheet-like graphene has grown perpendicular to a substrate with an arbitrary cross-sectional shape, and carbon black made of many graphite crystallites. The carbon material may be an aggregate in which many primary particles are gathered, or may be a strong aggregate (aggregate) in which the primary particles are strongly aggregated, or may be a weak aggregate in which the primary particles are weakly aggregated. These carbon materials can be manufactured by a conventional method, or commercially available products can be used.

The carbon material (A) may be a carbon material that has been subjected to a surface modification or modification treatment (e.g., functional group introduction, oxidation treatment, reduction treatment), may contain metals or the like, or may have some of the carbon atoms replaced with other atoms.

Examples of methods for producing nitrogen-doped carbon materials having a graphene structure in which nitrogen atoms have been substituted or introduced include a method of performing plasma treatment on a carbon material in a nitrogen atmosphere, as exemplified in "ACS NANO, 2010, 1790" and the like, and a method of performing plasma treatment on a cyclic compound that contains carbon and nitrogen in its chemical composition and has at least a ring structure in at least a portion, as exemplified in JP-A-2014-100617 and JP-A-2019-189495 and the like.

A cyclic compound having a ring structure means a group of organic compounds in which constituent atoms are bonded in at least one ring in the chemical structure. In other words, it is a general term for organic compounds having a ring structure based on a carbon skeleton. Therefore, the cyclic compound may be a monocyclic compound having one ring in one molecule, or a polycyclic compound having two or more rings, and may be various cyclic compounds such as a monocyclic compound in which a ring is formed by one type of atom, or a heterocyclic compound in which a ring is formed by two or more types of atoms. Furthermore, it may be an aromatic cyclic compound (typically, an aromatic hydrocarbon) having a conjugated unsaturated ring structure, or an alicyclic compound containing one or more saturated or unsaturated carbon rings that do not have aromaticity. Preferably, it is a cyclic compound having at least one unsaturated bond. There is no limit to the number of atoms that constitute such a ring structure, and it may be, for example, a compound having a small ring, a medium ring, or a large ring, and typically, a cyclic compound of about 3 to 10 members can be considered.

A preferred embodiment of the method for producing a nitrogen-doped carbon material is to generate plasma in a liquid containing the cyclic compound having a five-membered ring, a six-membered ring, or both in its chemical structure.

The nitrogen-doped carbon material obtained by the above method is considered to have a chemical structure in which several of the cyclic compounds, which are raw material compounds, are polymerized. For example, a 6-membered pyridine-type structure or a 5-membered pyrrole-type structure can exist at the end of the graphene structure. Therefore, it is preferable that the raw material compound used in the present invention has a 5-membered or 6-membered ring structure, since nitrogen atoms can be suitably introduced into the graphene structure. Such a cyclic compound may be a cyclic compound whose ring structure is composed of only carbon, or a heterocyclic compound whose ring structure contains atoms other than carbon. The cyclic compound may also contain atoms other than carbon and nitrogen. Specific examples of suitable compounds include pyrrole, pyrrolidine, imidazole, thiazole, piperidine, pyridine, 2-cyanopyridine, pyrazine, pyrimidine, triazine, quinoline, isoquinoline, xaquinoline, cinnoline, pteridine, indole, purine, aniline, 1-naphthylamine, 2-naphthylamine, phenylenediamine, and derivatives thereof. These compounds may be used alone or in combination of two or more.

The cyclic compound may have a substituent. Such a substituent may be various organic functional groups, and examples thereof include a hydrocarbon group, a hydroxy group, an aldehyde group, a carboxyl group, a carbonyl group, a halogeno group, a silicon-containing functional group, a sulfur-containing functional group, a nitrogen-containing functional group, and a phosphorus-containing functional group. More preferably, examples thereof include a hydrocarbon group represented by a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, a vinyl group, an aryl group, and the like; a hydroxy group, an aldehyde group, a carboxyl group, a carbonyl group, a halogeno group such as a fluoro group, a chloro group, or a bromo group; a silicon-containing functional group represented by an alkylsilyl group, and the like; a sulfur-containing functional group represented by a thiol group, a sulfo group, and the like; a nitrogen-containing functional group represented by an aldehyde group, a nitro group, and the like; and a phosphorus-containing functional group represented by a phosphonic acid group, and the like.

The cyclic compound may also be one that contains the above-mentioned cyclic compound as part of its structure. For example, it may be a compound such as a bipyridine compound or a phenylpyridine compound that contains pyridine as part of its structure. It may also be a polymer such as polypyrrole or polythiophene, in which multiple pyrroles or multiple thiophenes are bonded together.

As is clear from the above, the raw material compounds may naturally contain hydrogen and oxygen, unless they are present as different elements.
The raw material compound may be liquid at room temperature and normal pressure (typically, 25° C., 1 atm. The same applies below). For this reason, a liquid consisting of 100% raw material compound can be used as a liquid (liquid phase) containing the raw material compound. In addition, the raw material compound may be diluted with an appropriate solvent. In this case, the solvent is not particularly limited, and may be water, an organic solvent such as alcohol or benzene, or a mixed solvent thereof. In addition, when the raw material compound is solid at room temperature and normal pressure, it may be in the form of a solution in which it is dissolved in an appropriate solvent, or a dispersion in which the raw material compound is microscopically dispersed. The amount of raw material compound contained in the liquid can be appropriately adjusted.

A preferred embodiment of the method for producing a nitrogen-doped carbon material is a method in which a pair of linear electrodes is placed in a liquid containing the raw material compound, and the plasma is generated by applying a pulse voltage between the electrodes with a pulse width of 0.1 μs to 5 μs and a repetition frequency of 10 Hz to 150 Hz. With this configuration, most of the bubbles generated in the liquid by Joule heat generated between the linear electrodes can be maintained in a stable state in the liquid without floating up to the water surface, and plasma can be generated in the bubbles in a stable state. This makes it possible to produce a carbon-based catalyst more efficiently and stably.

In one preferred embodiment of the method for producing a carbon-based catalyst, the plasma is glow discharge plasma. The plasma generated in the liquid can be in the form of spark discharge, corona discharge, glow discharge, or arc discharge. In particular, glow discharge plasma can be used in the production of the nitrogen-doped carbon material as a more preferred form of in-liquid plasma. This makes it possible to generate non-equilibrium low-temperature plasma, and to efficiently synthesize the nitrogen-doped carbon material without destroying the structure of the raw material compound.

By generating the plasma in a liquid containing the raw material compounds, the action of active species such as positive and negative ions, electrons, and radicals that constitute the plasma results in a polymerization reaction of the raw material compounds contained in the liquid and the formation of a carbon skeleton. Regardless of the specific composition or structure of the nitrogen-doped carbon material produced in this way, the liquid, which was almost colorless and transparent to the human eye, changes color from brown to black as the plasma treatment progresses, confirming that the raw material compounds, which are typically organic, are converted to inorganic carbon. This phenomenon is similar to the change in appearance of organic polymer materials such as cellulose, in which oxygen and hydrogen are lost as carbonization progresses, the carbon concentration increases, and the appearance changes from brown to black.

The carbon material (A) used in the present invention may be the nitrogen-doped carbon material obtained by the plasma treatment, which may be used as is, or may be used after filtering with a membrane filter or the like, drying by heating in an oven or the like, or grinding in a mortar. In addition, the carbon material in a solid state may be added to a liquid containing the raw material compound, and then the plasma treatment may be performed, so that at least a part of the surface of the carbon material is covered with the nitrogen-doped carbon material, which may be used as the carbon material (A).

<Organoaluminum Compound (B)>
The organoaluminum compound (B) used in the present invention is a compound represented by the following general formula (BI):

R ^a _m Al(OR ^b ) _n H _p X _q ...(BI)
In formula (BI), R ^a and R ^b each represent a hydrocarbon group having 1 to 15 carbon atoms and may be the same or different from each other; X represents a halogen atom; m represents 1 to 3. n is an integer of 0 or more and 2 or less, p is an integer of 0 or more and 2 or less, q is an integer of 0 or more and 2 or less, and m+n+p+q=3.

The hydrocarbon group having 1 to 15 carbon atoms is, for example, an alkyl group, a cycloalkyl group, or an aryl group, specifically, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an isobutyl group, a pentyl group, a hexyl group, an octyl group, a cyclopentyl group, a cyclohexyl group, a phenyl group, a tolyl group, etc.

Specific examples of the organoaluminum compound (B) include trialkylaluminums such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, and tri-2-ethylhexylaluminum; dialkylaluminum halides such as dimethylaluminum chloride, diethylaluminum chloride, diisopropylaluminum chloride, and dimethylaluminum bromide; alkylaluminum sesquihalides such as methylaluminum sesquichloride, ethylaluminum sesquichloride, isopropylaluminum sesquichloride, butylaluminum sesquichloride, and ethylaluminum sesquibromide; methylaluminum dichloride, ethylaluminum dichloride, isopropylaluminum sesquichloride, and ethylaluminum sesquibromide. Examples of such compounds include alkylaluminum dihalides such as aluminum dichloride and ethylaluminum dibromide; alkylaluminum hydrides such as dimethylaluminum hydride, diethylaluminum hydride, dihydrophenylaluminum hydride, diisopropylaluminum hydride, di-n-butylaluminum hydride, diisobutylaluminum hydride, diisohexylaluminum hydride, diphenylaluminum hydride, dicyclohexylaluminum hydride, di-sec-heptylaluminum hydride, and di-sec-nonylaluminum hydride; and dialkylaluminum alkoxides such as dimethylaluminum ethoxide, diethylaluminum ethoxide, diisopropylaluminum methoxide, and diisobutylaluminum ethoxide.

Among the above, trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride, ethylaluminum dichloride, diisobutylaluminum hydride, and diethylaluminum ethoxide are particularly preferred.

<Transition metal compound (C)>
The transition metal compound (C) used in the present invention is a compound represented by the following general formula (CI).

L _m MX _n ... (C-I)
In formula (C-I), M represents an atom of Groups 3, 4, 5, 6, 7, 8, 9, 10, or 11 of the periodic table; The atom is selected from the group consisting of lanthanide atoms, preferably a transition metal atom of Group 4 of the periodic table, specifically a titanium atom, a zirconium atom or a hafnium atom.

L is a ligand, and a plurality of L may be the same or different from each other, and a plurality of L may be connected by a substituent in L, but at least one L contains at least one atom selected from the group consisting of boron, nitrogen, oxygen, phosphorus, sulfur, and selenium. In particular, it is preferable that at least one atom selected from the group consisting of boron, nitrogen, oxygen, phosphorus, sulfur, and selenium in L is covalently bonded or coordinately bonded to the M. Furthermore, it is particularly preferable that the atom bonded to the M is a nitrogen atom or an oxygen atom.
m is an integer of 2 or more, and is preferably 2.
n is an integer of 1 to 4 satisfying the valence of M, and is preferably 1 or 2.

X is a leaving group, and is selected from the group consisting of a hydrogen atom, a halogen atom, a hydrocarbon group, a halogen-containing group, a silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a phosphorus-containing group, a boron-containing group, an aluminum-containing group, a conjugated diene derivative group, and a neutral ligand capable of coordinating with a lone electron pair. When n is 2 or more, multiple Xs may be the same or different from each other, and may be bonded to each other to form a ring. Preferred are a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, an oxygen-containing group, or a conjugated diene derivative group.
The halogen atom includes fluorine, chlorine, bromine, iodine, etc., and is preferably chlorine or bromine.

Examples of the hydrocarbon group include linear or branched alkyl groups such as a methyl group, an ethyl group, a 1-propyl group, a 1-butyl group, a 1-pentyl group, a 1-hexyl group, a 1-heptyl group, a 1-octyl group, an isopropyl group, a sec-butyl group (butan-2-yl group), a tert-butyl group (2-methylpropan-2-yl group), an isobutyl group (2-methylpropyl group), a pentan-2-yl group, a 2-methylbutyl group, an isopentyl group (3-methylbutyl group), a neopentyl group (2,2-dimethylpropyl group), a cyamyl group (1,2-dimethylpropyl group), an isohexyl group (4-methylpentyl group), a 2,2-dimethylbutyl group, a 2,3-dimethylbutyl group, a 3,3-dimethylbutyl group, a thexyl group (2,3-dimethylbut-2-yl group), and a 4,4-dimethylpentyl group;
Linear or branched alkenyl groups or unsaturated double bond-containing groups such as vinyl group, allyl group, propenyl group (prop-1-en-1-yl group), iso-propenyl group (prop-1-en-2-yl group), allenyl group (prop-1,2-dien-1-yl group), but-3-en-1-yl group, crotyl group (but-2-en-1-yl group), but-3-en-2-yl group, methallyl group (2-methylallyl group), but-1,3-dienyl group, pent-4-en-1-yl group, pent-3-en-1-yl group, pent-2-en-1-yl group, iso-pentenyl group (3-methylbut-3-en-1-yl group), 2-methylbut-3-en-1-yl group, pent-4-en-2-yl group, and prenyl group (3-methylbut-2-en-1-yl group);
linear or branched alkynyl groups or unsaturated triple bond-containing groups, such as ethynyl, prop-2-yn-1-yl, and propargyl (prop-1-yn-1-yl); aromatic-containing linear or branched alkyl groups and unsaturated double bond-containing groups, such as benzyl, 2-methylbenzyl, 4-methylbenzyl, 2,4,6-trimethylbenzyl, 3,5-dimethylbenzyl, cuminyl (4-isopropylbenzyl), 2,4,6-tri-isopropylbenzyl, 4-tert-butylbenzyl, 3,5-di-tert-butylbenzyl, 1-phenylethyl, benzhydryl (diphenylmethyl), and cumyl;
cyclic saturated hydrocarbon groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cycloheptatrienyl group, a norbornyl group, a norbornenyl group, a 1-adamantyl group, and a 2-adamantyl group;
Aromatic substituents (aryl groups) such as phenyl, tolyl (methylphenyl), xylyl (dimethylphenyl), mesityl (2,4,6-trimethylphenyl), cumenyl (isopropylphenyl), julyl (2,3,5,6-tetramethylphenyl), 2,6-di-isopropylphenyl, 2,4,6-tri-isopropylphenyl, 4-tert-butylphenyl, 3,5-di-tert-butylphenyl, naphthyl, biphenyl, terphenyl, binaphthyl, acenaphthalenyl, phenanthryl, anthracenyl, pyrenyl, and ferrocenyl.
Among the above hydrocarbon groups, a methyl group, an iso-butyl group, a neopentyl group, a cyamyl group, a benzyl group, a phenyl group, a tolyl group, a xylyl group, a mesityl group, and a cumenyl group are preferable.

Examples of the halogen-containing group include a fluoromethyl group, a trifluoromethyl group, a trichloromethyl group, a pentafluoroethyl group, a 2,2,2-trifluoroethyl group, a fluorophenyl group, a difluorophenyl group, a trifluorophenyl group, a tetrafluorophenyl group, a pentafluorophenyl group, a trifluoromethylphenyl group, a bistrifluoromethylphenyl group, and a hexachloroantimonate anion. Among the halogen-containing groups, a pentafluorophenyl group is preferred.

Examples of the silicon-containing group include a trimethylsilyl group, a triethylsilyl group, a tri-iso-propylsilyl group, a diphenylmethylsilyl group, a tert-butyldimethylsilyl group, a tert-butyldiphenylsilyl group, a triphenylsilyl group, a tris(trimethylsilyl)silyl group, and a trimethylsilylmethyl group. Among the silicon-containing groups, a trimethylsilylmethyl group is preferred.

Examples of the oxygen-containing group include alkoxy groups such as hydroxyl, methoxy, ethoxy, n-propoxy, iso-propoxy, allyloxy, n-butoxy, sec-butoxy, iso-butoxy, tert-butoxy, benzyloxy, and methoxymethoxy, aryloxy groups such as phenoxy, 2,6-dimethylphenoxy, 2,6-di-iso-propylphenoxy, 2,6-di-tert-butylphenoxy, 2,4,6-trimethylphenoxy, and 2,4,6-tri-iso-propylphenoxy, furyl, benzofuryl, tetrahydrofuryl, pyranyl, tetrahydropyranyl, acetoxy, pivaloyloxy, benzoyloxy, trifluoroacetoxy, perchlorate, and periodate. Among the oxygen-containing groups, methoxy groups, ethoxy groups, iso-propoxy groups, and tert-butoxy groups are preferred.

Examples of the sulfur-containing group include a mesyl group (methanesulfonyl group), a phenylsulfonyl group, a tosyl group (p-toluenesulfonyl group), a triflyl group (trifluoromethanesulfonyl group), a nonaflyl group (nonafluorobutanesulfonyl group), a thiophenyl group, a mesylate group (methanesulfonate group), a tosylate group (p-toluenesulfonate group), a triflate group (trifluoromethanesulfonate group), a nonaflate group (nonafluorobutanesulfonate group), a thiophene group, and a benzothiophene group. Among the sulfur-containing groups, triflate (trifluoromethanesulfonate) is preferred.

Examples of the nitrogen-containing group include an amino group, a cyano group, a methylamino group, a dimethylamino group, an ethylamino group, a diethylamino group, an allylamino group, a diallylamino group, a benzylamino group, a dibenzylamino group, a nitro group, a pyrrolidinyl group, a piperidinyl group, a morpholyl group, a pyrrolyl group, a bistriflyl imide group, a pyridinyl group, a pyrimidinyl group, a quinolinyl group, a triazinyl group, an oxazoline group, an imidazole group, an indole group, and a carbazole group. Among the nitrogen-containing groups, a dimethylamino group, a diethylamino group, a pyrrolidinyl group, a pyrrolyl group, and a bistriflyl imide group are preferred.

The phosphorus-containing group may, for example, be a hexafluorophosphate anion.
Examples of the boron-containing group include tetrafluoroborate anion, tetrakis(pentafluorophenyl)borate anion, (methyl)(tris(pentafluorophenyl))borate anion, (benzyl)(tris(pentafluorophenyl))borate anion, tetrakis((3,5-bistrifluoromethyl)phenyl)borate anion, and groups represented by _BR4 (each R independently represents hydrogen, an alkyl group, an aryl group which may have a substituent, a halogen atom, etc.).

で表される四員環、あるいは

で表される四員環
（Ｍは、前記一般式［３］または［４］中のＭを表す。）
を形成可能な、ＡｌＲ₄（Ｒは水素、アルキル基、置換基を有してもよいアリール基またはハロゲン原子等を示す）で表される基などが挙げられる。 Examples of the aluminum-containing group include

or

(M represents M in the general formula [3] or [4].)
Examples of the groups include a group represented by AlR ₄ (R represents a hydrogen atom, an alkyl group, an aryl group which may have a substituent, a halogen atom, or the like) which can form the following formula:

Examples of the conjugated diene derivative group include a 1,3-butadienyl group, an isoprenyl group (2-methyl-1,3-butadienyl group), a piperylenyl group (1,3-pentadienyl group), a 2,4-hexadienyl group, a 1,4-diphenyl-1,3-pentadienyl group, a cyclopentadienyl group, and a metallocyclopentene group.

Examples of neutral ligands that can be coordinated with lone electron pairs include ethers such as diethyl ether, tetrahydrofuran, dioxane, and 1,2-dimethoxyethane; amines such as triethylamine and diethylamine; heterocyclic compounds such as pyridine, picoline, lutidine, oxazoline, oxazole, thiazole, imidazole, and thiophene; and organic phosphorus compounds such as triphenylphosphine, tricyclohexylphosphine, and tri-tert-butylphosphine.

The hydrocarbon group, halogen-containing group, silicon-containing group, oxygen-containing group, sulfur-containing group, nitrogen-containing group, phosphorus-containing group, boron-containing group, aluminum-containing group, conjugated diene divalent derivative group, and neutral ligand capable of coordinating with a lone electron pair may be further substituted with another substituent.

Examples of such transition metal compounds (C) include those described in JP-A-2003-206310, JP-A-2020-117711, JP-T-2009-537656, JP-T-2017-520548, JP-A-2004-269825, JP-A-2011-127121, JP-T-2016-527182, and JP-T-2017-535518, and preferably include transition metal compounds represented by the following general formula (C-II):

In the general formula (C-II), M represents a transition metal atom of Group 4 or Group 5 of the periodic table, specifically a titanium atom, a zirconium atom, a hafnium atom, a vanadium atom, a niobium atom, or a tantalum atom. Preferably, it is a transition metal atom of Group 4 of the periodic table, specifically a titanium atom, a zirconium atom, or a hafnium atom, and more preferably a titanium atom or a zirconium atom.

In addition, in the general formula (C-II), the dotted line connecting the nitrogen atom (N) and M generally indicates that the nitrogen atom (N) is coordinated to M, but in the present invention, it does not matter whether the nitrogen atom (N) is coordinated to M or not.

^R1 , ^R2 , ^R3 , ^R4 and ^R5 may be the same or different and represent a hydrogen atom, a halogen atom, a hydrocarbon group, a halogen-containing group, a silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a phosphorus-containing group, a boron-containing group, a germanium-containing group or a tin-containing group, and two or more of these may be linked to each other to form a ring.

Specific examples of the halogen atom, hydrocarbon group, halogen-containing group, silicon-containing group, oxygen-containing group, sulfur-containing group, nitrogen-containing group, phosphorus-containing group, and boron-containing group include the same as those exemplified as X in the general formula (C-I), and examples of the germanium-containing group or tin-containing group include groups in which the silicon of the silicon-containing group is substituted with germanium or tin. In addition, structures having the halogen-containing group, silicon-containing group, oxygen-containing group, sulfur-containing group, nitrogen-containing group, phosphorus-containing group, or boron-containing group as a substituent in the hydrocarbon group can also be exemplified as R ¹ , R ² , R ³ , R ⁴ , and R ⁵ .

Examples of the hydrocarbon group include linear or branched alkyl groups having 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a neopentyl group, and an n-hexyl group;
aryl groups having 6 to 30, preferably 6 to 20, carbon atoms, such as a phenyl group, a naphthyl group, a biphenyl group, a terphenyl group, a phenanthryl group, or an anthracenyl group;
Preferred are substituted aryl groups in which these aryl groups are substituted with 1 to 5 substituents such as a halogen atom, an alkyl group or alkoxy group having 1 to 30, preferably 1 to 20, carbon atoms, or an aryl group or aryloxy group having 6 to 30, preferably 6 to 20, carbon atoms.

From the viewpoint of olefin polymerization catalyst activity and of providing a high molecular weight ethylene polymer, ^R1 is preferably a group selected from a linear or branched hydrocarbon group having 1 to 20 carbon atoms, an alkyl group having 3 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms.

R ⁶ is selected from a hydrogen atom, a hydrocarbon group having 1 to 3 carbon atoms consisting only of primary or secondary carbon, an alkyl group having 4 or more carbon atoms, an aryl-substituted alkyl group, a monocyclic or bicyclic cyclic hydrocarbon group, an aryl group, and a halogen atom. Among these, from the viewpoint of olefin polymerization catalyst activity and from the viewpoint of providing a high molecular weight ethylene polymer, it is preferably a group selected from an alkyl group having 4 or more carbon atoms, an aryl-substituted alkyl group, a monocyclic or bicyclic cyclic hydrocarbon group, and an aryl group, and more preferably, a branched alkyl group such as a tert-butyl group; an aryl-substituted alkyl group such as a benzyl group, a 1-methyl-1-phenylethyl group (cumyl group), a 1-methyl-1,1-diphenylethyl group, or a 1,1,1-triphenylmethyl group (trityl group); or a cyclic hydrocarbon group having a ring structure having 6 to 15 carbon atoms, such as a cyclohexyl group, an adamantyl group, a norbornyl group, or a tetracyclododecyl group.

X is a leaving group, and is a substituent selected from the group consisting of a hydrogen atom, a halogen atom, a hydrocarbon group, an anionic ligand, and a neutral ligand capable of coordinating with a lone electron pair, and the anionic ligand is a halogen-containing group, a silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a phosphorus-containing group, a boron-containing group, an aluminum-containing group, or a conjugated diene derivative group. When n is 2 or more, the multiple Xs may be the same or different from one another and may be bonded to each other to form a ring. Preferably, it is a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, an oxygen-containing group, or a conjugated diene derivative group.

Specific examples of X include the same as those exemplified as X in the general formula (CI).
n is an integer of 1 to 4 satisfying the valence of M, and is preferably 1 or 2.

A carbon material (A) that satisfies the requirements (AI) and (A-II);
An organoaluminum compound (B) represented by the general formula (BI),
The olefin polymerization catalyst of the present invention, which contains the transition metal compound (C) represented by the general formula (CI), can produce an olefin polymer in which a carbon material is efficiently dispersed, with high polymerization activity.

The reason why the present invention exhibits its effects is not entirely clear, but the inventors speculate as follows.
In order for the transition metal compound (C) to exhibit catalytic activity, it is necessary to chemically extract the leaving group (X in formula (C-I)) from the electronically neutral transition metal compound (C) to form a cation. However, when only the organoaluminum compound (B) is contacted with the transition metal compound (C), the equilibrium between the neutral and cationic transition metal compound (C) is biased toward the neutral side, resulting in low catalytic activity, as shown in "Chem. Rev., 2000, 100, 1391" and the like. In order to bias this equilibrium toward the cationic side, it is necessary to physically or electronically shield the cations generated from the transition metal compound (C). It is presumed that the nitrogen atoms introduced into the two-dimensional sheet structure formed mainly by sp ² bond carbon coordinate to the cations generated from the transition metal compound (C), thereby physically or electronically shielding the cations. In particular, in the transition metal compound (C) having a heteroatom with high electronegativity, it is considered that the coordination of the nitrogen atoms in the carbon material (A) is promoted by strengthening the cationicity.

<Method for preparing an olefin polymerization catalyst>
In one preferred embodiment of the olefin polymerization catalyst of the present invention, the solid catalyst component (X) is prepared by contacting the carbon material (A), the organoaluminum compound (B) and the transition metal compound (C).

If the organoaluminum compound (B) and the transition metal compound (C) are in liquid form, they are preferably diluted with an inert solvent, and if they are in solid form, they are preferably dissolved in an inert solvent and brought into contact with the carbon material (A). Examples of inert solvents include aromatic hydrocarbons such as benzene, toluene, and xylene, aliphatic saturated hydrocarbons such as hexane, heptane, and decane, alicyclic hydrocarbons such as cyclohexane and methylcyclopentane, halogenated hydrocarbons such as ethylene chloride, chlorobenzene, and dichloromethane, and mixtures thereof.

The method of contacting the carbon material (A), the organoaluminum compound (B) and the transition metal compound (C) is not particularly limited as long as the effect of the present invention is achieved. For example, the method of adding an inert solvent containing the organoaluminum compound (B) or the transition metal compound (C) to the carbon material (A) and impregnating it into the pores of the carbon material (A), the method of immersing the carbon material (A) in an inert solvent containing the organoaluminum compound (B) or the transition metal compound (C) and leaving it to stand, the method of mixing the carbon material (A) with an inert solvent containing the organoaluminum compound (B) or the transition metal compound (C) by stirring, etc., the method of passing an inert solvent containing the organoaluminum compound (B) or the transition metal compound (C) through the carbon material (A), etc., may be used. The carbon material (A) may be physically or chemically fixed to a solid support (including powder, granulated particles, fibers, films, etc.), and may be heated during contact.

Among these, a method in which the carbon material (A) is mixed with an inert solvent containing the organoaluminum compound (B) or the transition metal compound (C) by stirring or the like is preferred, and after the contact operation, the contact liquid may be left to stand and the supernatant removed, or the inert solvent may be removed by a method such as filtration, and the mixture may be washed with the inert solvent as necessary.

The temperature during the heating operation depends on the solvent used, but is usually from the freezing point of the solvent to 200°C or less, preferably 150°C or less. The contact time depends on the contact method and temperature, but is usually from 30 seconds to 1,000 hours, preferably from 5 minutes to 120 hours.

In any step of the contact method, by adding component (G), fouling during the polymerization reaction can be suppressed to a higher degree and the particle properties of the resulting polymer can be further improved. As component (G), a compound having a polar functional group can be used, and nonionic surfactants are preferred, with polyalkylene oxide blocks, higher aliphatic amides, polyalkylene oxides, polyalkylene oxide alkyl ethers, alkyldiethanolamines, polyoxyalkylene alkylamines, glycerin fatty acid esters, and N-acyl amino acids being more preferred. These may be used alone or in combination of two or more.

The order of contacting the carbon material (A), the organoaluminum compound (B), and the transition metal compound (C) is not particularly limited as long as the effects of the present invention can be obtained.
A step (1-1) of contacting the carbon material (A) with the organoaluminum compound (B);
a step (1-2) of contacting the contact product obtained in the step (1-1) with the transition metal compound (C) to obtain a solid catalyst component (X);
A step (2-1) of contacting the transition metal compound (C) with the organoaluminum compound (B);
a step (2-2) of contacting the contact product obtained in the step (2-1) with the carbon material (A) to obtain a solid catalyst component (X);
A step (3-1) of contacting the carbon material (A) with the organoaluminum compound (B);
a step (3-2) of contacting the transition metal compound (C) with the organoaluminum compound (B);
and a step (3-3) of contacting the contact product obtained in the step (3-1) with the contact product obtained in the step (3-2) to obtain a solid catalyst component (X). In this case, the organoaluminum compound (B) used in the step (3-1) and the step (3-2) may be the same or different.

In the steps (1-1) and (3-1), the organoaluminum compound (B) can be used in an amount of preferably 0.1 mmol to 500 mmol, more preferably 0.2 mmol to 200 mmol, and even more preferably 0.5 mmol to 100 mmol, per 1 g of the carbon material (A).

In the steps (2-1) and (3-2), the organoaluminum compound (B) can be used in an amount of preferably 0.1 mmol to 3000 mmol, more preferably 0.5 mmol to 1000 mmol, and even more preferably 1 mmol to 500 mmol, per 1 mmol of the transition metal compound (C).

In the steps (1-2), (2-2), and (3-3), the transition metal compound (C) can be used in an amount of preferably 0.1 μmol to 1000 μmol, more preferably 0.5 μmol to 500 μmol, and even more preferably 1 μmol to 200 μmol, per 1 g of the carbon material (A).

In the production of olefin polymers, the solid catalyst component (X) may be used in a state of being suspended in an inert hydrocarbon, or in a dried state. In addition, the solid catalyst component (X) may be prepolymerized using an olefin that may be the same as or different from the olefin used in the production of the olefin polymer before use.

[Production method of olefin polymer]
The process for producing an olefin polymer of the present invention is characterized by comprising a step of polymerizing an olefin in the presence of the above-mentioned olefin polymerization catalyst of the present invention. In the present invention, the term "polymerization" may include copolymerization such as random copolymerization and block copolymerization in addition to homopolymerization.

The olefins to be polymerized in the present invention include ethylene, α-olefins, and cyclic olefins.
Among these, the α-olefin may be a linear or branched α-olefin having 3 to 30 carbon atoms, preferably 3 to 20 carbon atoms. More specifically, propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene are preferred. Among these, propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, and 3-methyl-1-pentene are preferred, and propylene, 1-butene, 1-hexene, and 4-methyl-1-pentene are more preferred.

Examples of cyclic olefins include cyclic olefins having 3 to 30 carbon atoms, preferably 3 to 20 carbon atoms. More specific examples include cyclopentene, cycloheptene, norbornene, 5-methyl-2-norbornene, tetracyclododecene, and 2-methyl-1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene.

The step of polymerizing the olefin is preferably a step of homopolymerizing ethylene in the presence of the solid catalyst component (X), or a step of copolymerizing ethylene with an α-olefin having 3 to 20 carbon atoms.

In the method for producing an olefin polymer of the present invention, the polymerization can be carried out by either a liquid phase polymerization method such as suspension polymerization or a gas phase polymerization method. Examples of inert hydrocarbon media used in liquid phase polymerization include aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, decane, dodecane, and kerosene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane; aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as ethylene chloride, chlorobenzene, and dichloromethane, or mixtures thereof, and the olefin itself can also be used as the solvent.

The lower limit of the temperature for polymerizing olefins in the method of the present invention is -20°C, preferably 0°C, more preferably 20°C, and particularly preferably 30°C, and the upper limit of the temperature for polymerizing olefins is 200°C, preferably 150°C, more preferably 100°C, and particularly preferably 80°C.

The polymerization pressure in the method of the present invention is usually between atmospheric pressure and 10 MPa, preferably between atmospheric pressure and 5 MPa, and the polymerization reaction can be carried out in any of batch, semi-continuous, and continuous modes.

In the process for producing an olefin polymer of the present invention, the polymerization can be carried out by any of a batch system, a semi-continuous system, and a continuous system.
The process for producing an olefin polymer of the present invention may be a so-called multi-stage polymerization process in which the polymerization reaction is carried out in two or more stages under different polymerization reaction conditions.

The molecular weight of the resulting olefin polymer can be adjusted by making hydrogen present in the polymerization system or by changing the polymerization temperature.
In the step of polymerizing the olefin, the component (G) can be present in order to suppress adhesion (fouling) to a polymerization reactor or to improve particle properties.

<Olefin Polymer>
One embodiment of the olefin polymer obtained by the method for producing an olefin polymer of the present invention includes an ethylene-based polymer containing ethylene-derived structural units in a range of preferably 90 mol% to 100 mol%, more preferably 95 mol% to 100 mol%. The ethylene-based polymer contains α-olefin-derived structural units having 3 to 20 carbon atoms in a total amount of preferably 0 mol% to 10 mol%, more preferably 0 mol% to 5 mol%, where the sum of the content of ethylene-derived structural units and the content of α-olefin-derived structural units having 3 to 20 carbon atoms is taken as 100 mol%.

Among these polymers, ethylene homopolymer, ethylene/propylene copolymer, ethylene/1-butene copolymer, ethylene/propylene/1-butene copolymer, ethylene/1-octene polymer, ethylene/1-hexene polymer, ethylene/4-methyl-1-pentene polymer, ethylene/propylene/1-octene polymer, ethylene/propylene/1-hexene polymer, and ethylene/propylene/4-methyl-1-pentene polymer are preferred. Also, so-called block copolymers (impact copolymers) obtained by mixing or continuously producing two or more types selected from these polymers may be used.

The olefin polymer obtained by the method for producing an olefin polymer contains the carbon material (A) in an amount of preferably 0.01% by weight or more and 25% by weight or less, more preferably 0.02% by weight or more and 10% by weight or less. The carbon material (A) is efficiently dispersed in the olefin polymer, and is expected to have high thermal conductivity, electrical conductivity, and weather resistance.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[Carbon materials]
The following carbon materials (A-1) to (A-4) and (A'-5) were used as the carbon materials. Each of the carbon materials was dried under reduced pressure at 100°C for 3 hours before use, and then cooled to room temperature under a nitrogen atmosphere before being used in the preparation of the solid catalyst component (X).

Carbon materials (A-1) to (A-4): Carbon materials obtained in Preparation Examples 1A to 4A below. Carbon material (A'-5): Graphene powder purchased from STREM (1-5 layers thick x 0.5-5 microns wide, surface area 650-750 ^m2 /g: product code 06-0318).

<Preparation Example 1A>
As a raw material compound, pyridine (Kanto Chemical Co., Ltd., special grade pyridine) was prepared and used as raw material compound-containing liquid 1-1.

Next, plasma was generated in the raw compound-containing liquid using the following device. Figure 1 is a schematic diagram of a solution plasma generating device 10 for generating plasma in a liquid. In this embodiment, the raw compound-containing liquid 1-1 prepared above is placed in a container 5 made of a glass beaker, and stirred by a stirring device 7 made of a magnetic stirrer. A pair of electrodes 6 for generating plasma are disposed in the raw compound-containing liquid 1-1 at a predetermined interval and are held in the container 5 via an insulating member 9. In this embodiment, a needle-shaped electrode 6 capable of locally concentrating an electric field is used. The electrode 6 is composed of a tungsten wire (manufactured by Nilaco Corporation) with a diameter of 1.0 mm, and the distance between the electrodes is set to 1.0 mm. In addition, only the tip (for example, about several mm) is exposed to suppress excess current that hinders electric field concentration, and the remaining part is insulated with an insulating member 9 made of fluororesin. In this embodiment, the insulating member 9 fixes the electrode 6 to the container 5 and also serves as a stopper to keep the electrode 6 and the container 5 watertight. The electrode 6 is connected to an external power source 8, and a pulse voltage of predetermined conditions is applied from this external power source 8. A bipolar pulse power source (MPP-HV04, power source for generating pulsed plasma in liquid, manufactured by Kurita Manufacturing Co., Ltd.) was used as the external power source 8.

In this embodiment, the application conditions of the pulse voltage for generating the solution plasma were a secondary voltage of 1500 V, a pulse width of 1.0 μs, and a repetition frequency of 50 kHz, and under these conditions, the solution plasma was generated in the raw material compound-containing liquid 1-1 for 15 minutes.
The raw material compound-containing liquid 1-1 was colorless and transparent, but immediately after the generation of the solution plasma, it turned yellowish, turned brown after about 5 minutes, and turned black and opaque after about 10 minutes.

After the solution plasma treatment, suction filtration was performed using a membrane filter (Merck Millipore, Omnipore(TM) membrane, maximum pore size 2.0 μm), and the resulting black powder was dried overnight in an oven at 80°C to obtain 0.20 g of black powder. This powder was pulverized in a mortar to obtain carbon material (A-1).

<Preparation Example 2A>
A solution plasma was generated in the same manner as in Preparation Example 1A, except that the application conditions of the pulse voltage were changed to secondary voltage: 1500 V, pulse width: 1.0 μs, and repetition frequency: 25 kHz.

After the solution plasma treatment, suction filtration was performed using a membrane filter (Merck Millipore, Omnipore(TM) membrane, maximum pore size 1.0 μm), and the resulting black powder was dried overnight in an oven at 80°C to obtain 0.20 g of black powder. This powder was pulverized in a mortar to obtain a carbon material (A-2).

<Preparation Example 3A>
As raw material compounds, EMIM-DCA (manufactured by ALDRICH, 1-ethyl-3-methyl imidazolium dicyanamide ≧98.0% (metals basis)) and aniline (manufactured by Kanto Chemical Co., Ltd., special grade aniline) were prepared, and these were mixed and stirred in a mixing ratio of 5 mL of EMIM-DCA + 95 mL of aniline to be used as raw material compound-containing liquid 1-2. Except for this, solution plasma was generated in the same manner as in Preparation Example 1A.
The raw material compound-containing liquid 1-2 was transparent and light orange in color, but changed color to brown about 5 minutes after the generation of the solution plasma, and turned opaque and black about 10 minutes later.

After the solution plasma treatment, suction filtration was performed using a membrane filter (Merck Millipore, Omnipore(TM) membrane, maximum pore size 2.0 μm), and the resulting black powder was dried overnight in an oven at 80°C to obtain 0.02 g of black powder. This powder was pulverized in a mortar to obtain a carbon material (A-3).

<Preparation Example 4A>
As raw material compounds, EMIM-DCA (manufactured by ALDRICH, 1-ethyl-3-methyl imidazolium dicyanamide ≧98.0% (metals basis)) and aniline (manufactured by Kanto Chemical Co., Ltd., special grade aniline) were prepared, and these were mixed and stirred in a mixing ratio of 10 mL of EMIM-DCA + 90 mL of aniline to be used as raw material compound-containing solution 1-3. Except for changing the application conditions of the pulse voltage to secondary voltage: 1500 V, pulse width: 1.5 μs, and repetition frequency: 30 kHz, solution plasma was generated in the same manner as in Preparation Example 1A.

After the solution plasma treatment, suction filtration was performed using a membrane filter (Merck Millipore, Omnipore(TM) membrane, maximum pore size 1.0 μm), and the resulting black powder was dried overnight in an oven at 80°C to obtain 0.02 g of black powder. This powder was pulverized in a mortar to obtain carbon material (A-4).

<Nitrogen content>
The nitrogen content of the carbon materials (A-1) to (A-4) and (A'-5) was determined by X-ray photoelectron spectroscopy (XPS) (VersaProbe II manufactured by ULVAC-PHI, Inc.). Narrow scan analysis was performed under the following analysis conditions, and the nitrogen atom concentration was determined from the peak intensity of the N1s narrow spectrum, and the carbon atom concentration was determined from the peak intensity of the C1s narrow spectrum, and the molar ratio of nitrogen atoms/carbon atoms was calculated. The results are shown in Table 1.
(Analysis conditions)
X-ray source: Mg-Kα ray X-ray generation current: 1.7mA
X-ray generating voltage: 25 kV

[Organoaluminum Compounds]
As the organoaluminum compound, the following organoaluminum compound (B-1) was used. The organoaluminum compound (B-1) was used after being diluted to 1.0 mol/L as a decane solution.
Organoaluminum compound (B-1): Triisobutylaluminum (TIBAL) from Tosoh Finechem Co., Ltd.

[Transition metal compounds]
As the transition metal compounds, transition metal compounds (C-1) and (C'-2) represented by the following formulas (C-1) and (C'-2) were produced by known methods and used.

<Identification of Transition Metal Compound (C)>
The structures of the transition metal compounds were determined by standard measurements using a 270 MHz ¹ H-NMR (GSH-270 manufactured by JEOL Ltd.) or the like.

[Preparation of solid catalyst component (X)]
<Preparation Example 1X>
In a Schlenk flask with a volume of 30 mL and thoroughly purged with nitrogen, 100 mg of carbon material (A-1) and 5 mL of toluene were added, and stirring was started using a rotor. 0.25 mL of a decane solution of an organoaluminum compound (B-1) (0.25 mmol in terms of an organoaluminum compound (B-1)) was added to this suspension, and stirring was continued at room temperature for 30 minutes. Thereafter, 3.0 μmol of a transition metal compound (C-1) was added as a toluene solution, and stirring was continued for another 30 minutes at room temperature to prepare a slurry of a solid catalyst component (X-1) with a solid concentration of the carbon material (A-1) of 10.0 g/L.

<Preparation Examples 2X to 5X>
A solid catalyst component (X) was prepared in the same manner as in Preparation Example 1X, except that the carbon materials (A-2) to (A-4) and (A'-5) were used instead of the carbon material (A-1). Slurries of (X-2) to (X-5) were prepared.

<Preparation Example 6X>
In a Schlenk flask with a volume of 30 mL and thoroughly purged with nitrogen, 100 mg of carbon material (A'-5), 30 μL of pyridine (Fujifilm Wako Pure Chemical Industries, pyridine (dehydrated) for organic synthesis), and 5 mL of toluene were added, and stirring was started using a rotor. 0.25 mL of a decane solution of organoaluminum compound (B-1) (0.25 mmol in terms of organoaluminum compound (B-1)) was added to this suspension, and stirring was continued for 30 minutes at room temperature. Thereafter, 3.0 μmol of transition metal compound (C-1) was added as a toluene solution, and stirring was continued for another 30 minutes at room temperature to prepare a slurry of solid catalyst component (X-6) with a solid concentration of carbon material (A) of 10.0 g/L.

<Preparation Example 7X>
A slurry of a solid catalyst component (X-7) was prepared in the same manner as in Preparation Example 3X , except that the organoaluminum compound (B-1) was not used.

<Preparation Example 8X>
A slurry of a solid catalyst component (X-8) was prepared in the same manner as in Preparation Example 3X , except that the transition metal compound (C-1) was replaced with the transition metal compound (C'-2).

[Production of Olefin Polymer]
Example 1
In a 1-liter SUS autoclave reactor that had been thoroughly purged with nitrogen, 500 milliliters of heptane was added under a nitrogen atmosphere, and ethylene was then passed through to saturate the reactor with ethylene. Next, 0.375 mL of a decane solution of the organoaluminum compound (B-1) (0.375 mmol in terms of the organoaluminum compound (B-1)) and an amount of slurry equivalent to the amount shown in Table 1 as the solid content of the carbon material (A-1) were extracted from the slurry of the solid catalyst component (X-1) obtained in Preparation Example 1 and charged into the reactor. Thereafter, the temperature and pressure were raised to 80° C. and 0.8 MPaG with ethylene, and a polymerization reaction was carried out for 60 minutes at a rotation speed of 350 rpm. After the reaction was completed, the contents in the reactor were filtered and dried under reduced pressure at 80° C. for 10 hours to obtain the amount of olefin polymer shown in Table 1.

<Examples 2 to 4>
Polymerization reactions were carried out in the same manner as in Example 1, except that slurries of solid catalyst components (X-2) to (X-4) obtained in Preparation Examples 2X to 4X were used instead of solid catalyst component (X-1), and the amounts shown in Table 1 were charged into the reactor as the solid content of the carbon material. After completion of the reaction, the contents in the reactor were filtered and dried under reduced pressure at 80° C. for 10 hours, thereby obtaining the amount of olefin polymer shown in Table 1.

<Comparative Examples 1 and 2>
Polymerization reactions were carried out in the same manner as in Example 1, except that slurries of the solid catalyst components (X-5) and (X-6) obtained in Preparation Examples 5X and 6X were used instead of the solid catalyst component (X-1), and the amounts shown in Table 1 were charged into the reactor as the solid content of the carbon material. After completion of the reaction, the contents in the reactor were filtered and dried under reduced pressure at 80° C. for 10 hours, thereby obtaining the amount of olefin polymer shown in Table 1.

<Comparative Example 3>
A polymerization reaction was carried out in the same manner as in Example 1, except that no organoaluminum compound (B-1) was used, that the slurry of solid catalyst component (X-7) obtained in Preparation Example 7X was used instead of solid catalyst component (X-1), and that the amount of the solid carbon material was charged into the reactor in the amount shown in Table 1. After completion of the reaction, the content in the reactor was filtered and dried under reduced pressure at 80° C. for 10 hours, thereby obtaining an olefin polymer in the amount shown in Table 1.

<Comparative Example 4>
A polymerization reaction was carried out in the same manner as in Example 1, except that the slurry of solid catalyst component (X-8) obtained in Preparation Example 8X was used instead of solid catalyst component (X-1), and the amount of the carbon material solid content shown in Table 1 was charged into the reactor. After the reaction was completed, the content in the reactor was filtered and dried under reduced pressure at 80° C. for 10 hours, thereby obtaining the amount of olefin polymer shown in Table 1.

The carbon material (A) constituting the olefin polymerization catalyst of the embodiment has a high nitrogen content, and it can be seen that a larger amount of olefin polymer can be obtained compared to the comparative example in which a carbon material with a low nitrogen content was used. In addition, even when a nitrogen atom-containing compound that is not introduced into the graphene structure was separately added to the carbon material with a low nitrogen content, the polymer yield did not increase.

It can also be seen that the examples using organoaluminum compound (B) produce more olefin polymers than the comparative examples not using organoaluminum compound (B). It can also be seen that the examples using transition metal compound (C-1) having a heteroatom as the transition metal compound produce more olefin polymers than the comparative examples using transition metal compound (C'-2) not having a heteroatom.

2 Liquid (liquid phase)
4. Solution Plasma (Plasma Phase)
5 container 6 electrode 7 stirring device 8 external power source 9 insulating member 10 solution plasma generating device

Claims (5)

A carbon material (A) that satisfies the following requirements (AI) and (A-II);
An organoaluminum compound (B) represented by the following general formula (BI),
and a transition metal compound (C) represented by the following general formula (C- II ):
(A-I) The nitrogen atom/carbon atom molar ratio measured by X-ray photoelectron spectroscopy (XPS) is 0.003 or more and 0.300 or less;
(A-II) A nitrogen-doped carbon material having a graphene structure in which nitrogen atoms are substituted or introduced;
R ^a _m Al(OR ^b ) _n H _p X _q ...(BI)
[In general formula (B-I), R ^a and R ^b represent a hydrocarbon group having 1 to 15 carbon atoms and may be the same or different, X represents a halogen atom, m represents an integer of 1 to 3, n represents an integer of 0 to 2, p represents an integer of 0 to 2, q represents an integer of 0 to 2, and m+n+p+q=3.]

[In general formula (C-II), M represents a transition metal atom of Group 4 or 5 of the periodic table,
R ¹ , R ² , R ³ , R ⁴ , and R ⁵ may be the same or different and each represent a hydrogen atom, a halogen atom, a hydrocarbon group, a halogen-containing group, a silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a phosphorus-containing group, a boron-containing group, a germanium-containing group, or a tin-containing group, two or more of which may be linked to each other to form a ring;
R6 ^represents a hydrogen atom, a hydrocarbon group having 1 to 3 carbon atoms consisting only of primary or secondary carbon, an alkyl group having 4 or more carbon atoms, an aryl group-substituted alkyl group, a monocyclic or bicyclic cyclic hydrocarbon group, an aryl group, or a halogen atom;
n is an integer of 1 to 4 that satisfies the valence of M;
X is a leaving group selected from the group consisting of a hydrogen atom, a halogen atom, a hydrocarbon group, a halogen-containing group, a silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a phosphorus-containing group, a boron-containing group, an aluminum-containing group, a conjugated diene derivative group, and a neutral ligand capable of coordinating with a lone electron pair, and when n is 2 or more, multiple Xs may be the same or different from each other and may be bonded to each other to form a ring. 2. The olefin polymerization catalyst according to claim 1 , wherein M in the general formula (C- II ) is a transition metal atom of Group 4 of the periodic table. 3. The olefin polymerization catalyst according to claim 1, wherein the nitrogen atom/carbon atom molar ratio in the requirement (AI) is 0.005 or more and 0.100 or less. A method for producing an olefin polymer, comprising a step of polymerizing an olefin in the presence of the olefin polymerization catalyst according to any one of claims 1 to 3 . The method for producing an olefin polymer according to claim 4 , wherein the step of polymerizing an olefin is a step of homopolymerizing ethylene or a step of copolymerizing ethylene with a linear or branched α-olefin having 3 to 30 carbon atoms.