JP2018145402A - Catalyst for producing ultrahigh-molecular-weight polyethylene particle and ultrahigh-molecular-weight polyethylene particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrahigh-molecular-weight polyethylene particle excellent in flowability and mechanical characteristics, to provide a catalyst capable of producing the polyethylene particle and to provide a method for efficiently producing the ultrahigh-molecular-weight polyethylene particle.SOLUTION: The catalyst for producing an ultrahigh-molecular-weight polyethylene particle includes (A) a specific transition metal compound, (B) an organic-modified clay powder modified with an aliphatic salt and having a median diameter of 4 μm to 20 μm and a geometric standard deviation of the particle size of 0.15 or less, and preferably containing 90% or more of an organic-modified clay powder having a circularity of 0.9 to 1, and (C) an organoaluminum compound. The method for producing an ultrahigh-molecular-weight polyethylene particle comprises performing the homopolymerization or copolymerization of ethylene in the presence of the catalyst for producing an ultrahigh-molecular-weight polyethylene particle.SELECTED DRAWING: None

Description

  The present invention relates to a catalyst for producing ultra high molecular weight polyethylene particles and ultra high molecular weight polyethylene particles. More specifically, the present invention relates to ultra high molecular weight polyethylene particles having high fluidity and excellent mechanical properties and processability. The present invention relates to a catalyst for producing ultra-high molecular weight polyethylene particles that enables efficient production of molecular weight polyethylene particles.

  Conventionally, ultra-high molecular weight polyethylene has a viscosity average molecular weight (may be abbreviated as Mv) reaching 1 million to 10 million, so impact resistance, self-lubricating property, chemical resistance, Because it has the effect of being excellent in dimensional stability, light weight, food stability, etc., it has physical properties comparable to engineering plastics and is molded by various molding methods such as injection molding, extrusion molding, compression molding, etc. It is used for applications such as food industry line parts, machine parts, and sporting goods.

  However, the ultra-high molecular weight polyethylene produced by a normal Ziegler catalyst has a ratio (molecular weight distribution (weight average molecular weight (may be abbreviated as Mw)) and number average molecular weight (may be abbreviated as Mn). Mw / Mn may be abbreviated as M) /), which is larger than 5 and has a very large molecular weight distribution in which a large amount of ultra high molecular weight components and low molecular weight components are mixed. The ultrahigh molecular weight component has an adverse effect of reducing the molding processability when forming a molded body. On the other hand, the low molecular weight component lowers the mechanical properties such as abrasion resistance or increases the number of molecular chain ends when it is made into a fiber, which causes a decrease in fiber strength by inhibiting crystallization. It was a factor that deteriorated the characteristics of ultrahigh molecular weight polyethylene.

  As means for solving these problems, ultrahigh molecular weight polyethylene having a molecular weight distribution of 3.0 or less has been proposed by using a metallocene catalyst (see, for example, Patent Document 1).

  In addition, general polyethylene is shipped as pellets from the manufacturing plant, but because ultra-high molecular weight polyethylene is shipped as particles, there are cases where fluidity is low due to the influence of particle shape, particle size, particle size distribution or charging, It is also necessary to take measures against dust explosions.

JP 09-291112 A

  The smaller the particle diameter of the polyethylene particles, the higher the ratio of the surface area to the weight. Therefore, the fluidity is liable to decrease due to friction or static electricity. Further, since the fine particles may cause dust explosion, it has been desired that the ultrahigh molecular weight polyethylene particles do not contain fine particles.

  On the other hand, since ultrahigh molecular weight polyethylene particles have poor solubility as the particle size increases, it becomes difficult to process them, and it has also been desired not to include coarse particles.

  Fine particles and coarse particles can also be removed by classification such as sieving, but the working environment is deteriorated due to dust generated at that time, the risk of dust explosion due to fine particles, and production by disposal of the removed particles There are issues such as increased costs.

  Therefore, an ultrahigh molecular weight polyethylene particle having a narrow particle size distribution that does not contain fine particles and coarse particles at the time of polymerization and a method for producing the same have been desired.

  In addition, the fluidity of the ultrahigh molecular weight polyethylene particles is also affected by the particle shape, and the fluidity improves as the shape becomes closer to a true sphere. Therefore, ultrahigh molecular weight polyethylene particles having a more spherical shape have also been desired.

  Therefore, in the present invention, there is provided an ultrahigh molecular weight polyethylene particle that does not have fine and coarse particles, has a uniform particle size, and has excellent fluidity, and an ultrahigh molecular weight polyethylene particle production catalyst that can efficiently produce it. It is to provide.

  As a result of intensive studies to solve the above problems, the present inventors have obtained from a transition metal compound having a specific structure, an organically modified clay powder modified with an aliphatic salt having a specific shape, and an organoaluminum compound. The present inventors have found an ultrahigh molecular weight polyethylene particle production catalyst, an ultrahigh molecular weight polyethylene particle that is excellent in fluidity and does not have fine and coarse particle diameters, and has completed the present invention.

  That is, the present invention provides a transition metal compound (A) represented by the following general formula (1),

[Wherein, M ¹ is a titanium atom, a zirconium atom or a hafnium atom, and X is independently a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, carbon An alkylamino group having 1 to 20 carbon atoms, an alkylsilyl group having 1 to 20 carbon atoms, a substituent having oxygen introduced between carbon-carbon bonds of a hydrocarbon group having 1 to 20 carbon atoms, carbonization having 1 to 20 carbon atoms A substituent in which a part of the hydrogen group is substituted with an alkylamino group having 1 to 20 carbon atoms, a substituent in which a part of carbons in the hydrocarbon group having 1 to 20 carbon atoms is substituted with silicon, and R ¹ is A cyclopentadienyl group represented by formula (2);

(In the formula, each R ⁴ independently represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an alkylsilyl group having 1 to 20 carbon atoms, or 1 carbon atom. A substituent in which oxygen is introduced between the carbon-carbon bonds of a hydrocarbon group having ˜20, a substituent in which a part of the hydrocarbon group having 1 to 20 carbon atoms is substituted with an alkylamino group having 1 to 20 carbon atoms, carbon (This is a substituent obtained by substituting a part of carbons of the hydrocarbon group of 1 to 20 with silicon.)
R ² is a fluorenyl group having an amino group represented by the following general formula (3),

(Wherein R ⁵ and R ⁶ are each independently a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 30 carbon atoms, C1-C20 arylalkylamino group, C1-C20 alkyl silyl group, C1-C20 hydrocarbon group, the substituent which introduce | transduced oxygen between the carbon-carbon bonds, C1-C20 A substituent obtained by substituting a part of the hydrocarbon group with an alkylamino group having 1 to 20 carbon atoms, a substituent obtained by substituting part of the carbons of the hydrocarbon group having 1 to 20 carbons with silicon, R ⁵ and (At least one of R ⁶ is an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 30 carbon atoms, or an arylalkylamino group having 7 to 30 carbon atoms.)
R ³ is a crosslinking unit of R ¹ and R ² represented by the following general formula (4) or the following general formula (5),

(In the formula, each R ⁷ independently represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, or 1 to 1 carbon atoms. 20 alkylsilyl groups, substituents in which oxygen is introduced between the carbon-carbon bonds of hydrocarbon groups having 1 to 20 carbon atoms, and some of the hydrocarbon groups having 1 to 20 carbon atoms are alkyl groups having 1 to 20 carbon atoms. A substituent substituted with an amino group, a substituent obtained by substituting a part of carbons of a hydrocarbon group having 1 to 20 carbon atoms with silicon, and M ² is a silicon atom, a germanium atom or a tin atom.)
n is an integer of 1-5. ]
Modified with an aliphatic salt represented by the following general formula (6), an organically modified clay powder (B) having a median diameter of 4 μm to 20 μm and a geometric standard deviation of particle diameter of 0.15 or less,

(Wherein R ^{8 to} R ¹⁰ are each independently an alkyl group having 1 to 30 carbon atoms, an alkyl alkoxy group having 1 to 30 carbon atoms, an alkylamino group having 1 to 30 carbon atoms, and an alkyl having 1 to 30 carbon atoms. A silyl group, a substituent in which oxygen is introduced between carbon-carbon bonds of the alkyl group having 1 to 30 carbon atoms, and a part of the alkyl group having 1 to 30 carbon atoms to an alkylamino group having 1 to 30 carbon atoms. A substituted substituent, a substituent obtained by substituting a part of carbons of the alkyl group having 1 to 30 carbon atoms with silicon, and at least one of R ^{8 to} R ¹⁰ is an alkyl group having 10 or more carbon atoms; M ³ is an atom of Group 15 of the periodic table, and [A ⁻ ] is an anion.)
Further, the present invention relates to a catalyst for producing ultrahigh molecular weight polyethylene particles, comprising an organoaluminum compound (C), and ultrahigh molecular weight polyethylene particles.

  The present invention is described in detail below.

  The ultra high molecular weight polyethylene particle production catalyst of the present invention is a median diameter of 4 μm modified with a transition metal compound (A) represented by the general formula (1) and an aliphatic salt represented by the general formula (6). The organic modified clay powder (B) and the organoaluminum compound (C) having a particle size of 20 μm or less and a geometric standard deviation of 0.15 or less are included.

The transition metal compound constituting the ultra-high molecular weight polyethylene particles for producing the catalyst of the present invention (A) is a transition metal compound represented by the general formula (1), a cyclopentadienyl group and R ² is R ¹ And having a structure in which M ¹ is sandwiched by a fluorenyl group having an amino group, and R ¹ and R ² are bridged by R ³ .

Here, M ¹ is a titanium atom, a zirconium atom or a hafnium atom, and these specific metal atoms make it possible to efficiently produce ultrahigh molecular weight polyethylene particles having a very high molecular weight. Zirconium atoms or hafnium atoms are preferred because they become catalysts for producing ultrahigh molecular weight polyethylene particles capable of producing molecular weight polyethylene particles with high production efficiency.

  X is independently a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, or an alkylsilyl group having 1 to 20 carbon atoms. Group, a substituent in which oxygen is introduced between carbon-carbon bonds of a hydrocarbon group having 1 to 20 carbon atoms, and a part of the hydrocarbon group having 1 to 20 carbon atoms is substituted with an alkylamino group having 1 to 20 carbon atoms And a substituent obtained by substituting a part of carbon of a hydrocarbon group having 1 to 20 carbon atoms with silicon, and by using these specific substituents, ultrahigh molecular weight polyethylene particles having a very high molecular weight are produced. It becomes possible. Specific examples of X include, for example, halogen atoms such as hydrogen atom, chlorine atom, bromine atom and iodine atom, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group and isomer substituents thereof. C1-C30 alkyl group, such as a phenyl group, an indenyl group, a naphthyl group, a fluorenyl group, a biphenylenyl group, a C6-C30 aryl group, a benzyl group, a phenylethyl group, a diphenylmethyl group, a diphenylethyl group And an arylalkyl group having 7 to 30 carbon atoms, such as an alkylaryl group having 7 to 30 carbon atoms such as a methylphenyl group, an ethylphenyl group, and a methylnaphthyl group, and an alkylsilyl group such as a trimethylsilyl group.

R ¹ is a cyclopentadienyl group represented by the general formula (2), and each R ⁴ is independently a hydrogen atom, a halogen atom, a C 1-30 hydrocarbon group, or a C 1-20 carbon atom. Alkylamino group, alkylsilyl group having 1 to 20 carbon atoms, substituent having oxygen introduced between carbon-carbon bonds of hydrocarbon group having 1 to 20 carbon atoms, part of hydrocarbon group having 1 to 20 carbon atoms Is a substituent obtained by substituting a C 1-20 alkylamino group, a part of the C 1-20 hydrocarbon group with silicon substituted by silicon, and the molecular weight is determined by these specific substituents. Can be produced. Specific examples of R ⁴ can be the same as those of X described above. Specific examples of R ¹ include, for example, a cyclopentadienyl group, a methylcyclopentadienyl group, ethyl Cyclopentadienyl group, n-butyl-cyclopentadienyl group, dimethylcyclopentadienyl group, diethylcyclopentadienyl group, methoxycyclopentadienyl group, dimethylamino-cyclopentadienyl group, trimethylsilyl-cyclopenta A dienyl group etc. are mentioned.

R ² is a fluorenyl group having an amino group represented by the general formula (3), and R ⁵ and R ⁶ are each independently a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, a carbon number Carbon of 1-20 alkylamino group, C6-C30 arylamino group, C7-C30 arylalkylamino group, C1-C20 alkylsilyl group, C1-C20 hydrocarbon group A substituent in which oxygen is introduced between the carbon and carbon bonds, a substituent in which part of the hydrocarbon group having 1 to 20 carbon atoms is substituted with an alkylamino group having 1 to 20 carbon atoms, or a hydrocarbon group having 1 to 20 carbon atoms In which at least one of R ⁵ and / or R ⁶ is an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 30 carbon atoms, or a carbon number. 7-30 arylalkyls An amino group, in particular a dialkylamino group having 1 to 20 carbon atoms is preferably a diarylamino alkylamino group diarylamino group, or a C7-30 having 6 to 30 carbon atoms. These specific substituents make it possible to produce an ethylene polymer having a very high molecular weight. Specific examples of R ⁵ and R ⁶ are the same as those described above for X, and further include a diphenylamino group, a dibenzylamino group, etc. Specific examples of R ² include 2-dimethylaminofluorenyl group, 2-diethylaminofluorenyl group, 2-diisopropylaminofluorenyl group, 2,7-bis (diethylamino) -fluorenyl group, 2,7-bis (diisopropylamino) -fluorenyl group Etc. Here, when neither R ⁵ nor R ⁶ is an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 30 carbon atoms, or an arylalkylamino group having 7 to 30 carbon atoms, the obtained catalyst is used. Even if it uses for manufacture of an ethylene-type polymer, an extremely high molecular weight ethylene-type polymer cannot be manufactured efficiently.

R ³ is a bridging unit of R ¹ and R ² and is a bridging unit represented by the general formula (4) or the general formula (5). R ⁷ is independently a hydrogen atom, halogen, Atom, hydrocarbon group having 1 to 30 carbon atoms, alkoxy group having 1 to 20 carbon atoms, alkylamino group having 1 to 20 carbon atoms, alkylsilyl group having 1 to 20 carbon atoms, hydrocarbon group having 1 to 20 carbon atoms A substituent in which oxygen is introduced between the carbon-carbon bonds, a substituent in which part of the hydrocarbon group having 1 to 20 carbon atoms is substituted with an alkylamino group having 1 to 20 carbon atoms, and carbonization having 1 to 20 carbon atoms It is a substituent obtained by substituting a part of carbon of a hydrogen group with silicon, and by using these specific substituents, it becomes possible to produce ultrahigh molecular weight polyethylene particles having a high molecular weight. As specific examples of R ^7, the same examples as those of X described above can be given. M ² is a silicon atom, a germanium atom, or a tin atom.

  And n is an integer of 1-5.

  The transition metal compound (A) is a transition metal compound having a ligand having a structure in which a cyclopentadienyl group (or a substituted cyclopentadienyl group) and a fluorenyl group having an amino group are combined. For example, diphenylsilanetetrayl (cyclopentadienyl) (2- (dimethylamino) -9-fluorenyl) zirconium dichloride, diphenylsilanetetrayl (cyclopentadienyl) (2,7-bis (dimethylamino) -9- Fluorenyl) zirconium dichloride, diphenylsilanetetrayl (cyclopentadienyl) (2- (diethylamino) -9-fluorenyl) zirconium dichloride, diphenylsilanetetrayl (cyclopentadienyl) (2,7-bis (diethylamino) -9 -Fluorenyl) Luconium dichloride, diphenylmethylene (cyclopentadienyl) (2- (dimethylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2,7-bis (dimethylamino) -9-fluorenyl) Zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2- (diethylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2,7-bis (diethylamino) -9-fluorenyl) zirconium dichloride, etc. Zirconium compounds, compounds in which zirconium atoms are changed to titanium atoms or hafnium atoms, and dichloro bodies of the above transition metal compounds are dimethyl, diethyl, dihydro, diphenyl, and diben. Examples of such a compound include a zirconium compound or a hafnium compound because it can be used as a catalyst system for producing polyethylene capable of producing ultrahigh molecular weight polyethylene particles with high production efficiency. It is preferable.

  The organically modified clay powder (B) constituting the catalyst for producing ultrahigh molecular weight polyethylene particles of the present invention has a median diameter of 4 μm or more and 20 μm or less modified with an aliphatic salt represented by the general formula (6). Further, it is an organically modified clay powder having a geometric standard deviation of particle size of 0.15 or less.

Here, R ^{8 to} R ¹⁰ are each independently an alkyl group having 1 to 30 carbon atoms, an alkyl alkoxy group having 1 to 30 carbon atoms, an alkylamino group having 1 to 30 carbon atoms, and an alkyl having 1 to 30 carbon atoms. A silyl group, a substituent in which oxygen is introduced between carbon-carbon bonds of the alkyl group having 1 to 30 carbon atoms, and a part of the alkyl group having 1 to 30 carbon atoms to an alkylamino group having 1 to 30 carbon atoms. A substituted substituent, a substituent obtained by substituting a part of carbons of the alkyl group having 1 to 30 carbon atoms with silicon, and at least one of R ^{8 to} R ¹⁰ is an alkyl group having 10 or more carbon atoms. . When any of R ^{8 to} R ¹⁰ is an alkyl group having less than 10 carbon atoms or a substituent other than an alkyl group, it is difficult for the resulting catalyst to efficiently produce ultrahigh molecular weight polyethylene particles.

Specific examples of R ^{8 to} R ¹⁰ include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, aryl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, neopentyl, tert-pentyl, n-hexyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl Group, oleyl group, behenyl group and other alkyl groups having 1 to 30 carbon atoms; methoxy group, ethoxy group, propoxy group, butoxy group, isopropoxy group and other alkyl alkoxy groups having 1 to 30 carbon atoms; dimethylamino group, diethylamino group Group, dipropylamino group, dibutylamino group, diisopropylamino group, etc. An alkylamino group having ˜30; a trimethylsilyl group, a tri-tert-butylsilyl group, a ditert-butylmethylsilyl group, a tert-butyldimethylsilyl group, etc., an alkylsilyl group having 1 to 30 carbon atoms; a methoxymethylene group, an ethoxymethylene group, etc. A substituent in which oxygen is introduced between the carbon-carbon bond of the alkyl group having 1 to 30 carbon atoms; a part of the alkyl group having 1 to 30 carbon atoms such as a dimethylaminomethylene group and a diethylaminomethylene group; A substituent in which a part of the carbon atoms of the alkyl group having 1 to 30 carbon atoms such as a trimethylsilylmethylene group and a tert-butyldimethylsilylmethylene group are substituted with silicon, and the like. .

At least one substituent among the R ^{8 to} R ¹⁰ is an alkyl group having 10 or more carbon atoms, and examples thereof include a decyl group, a dodecyl group, a tetradecyl group, a hexadecyl group, an octadecyl group, an oleyl group, and a behenyl group. be able to.

The M ³ is an atom belonging to Group 15 of the periodic table, and when it is an atom other than Group 15 of the periodic table, the resulting catalyst makes it difficult to efficiently produce ultrahigh molecular weight polyethylene particles. . Examples of M ³ include a nitrogen atom and a phosphorus atom.

The [A ⁻ ] is an anion and may be any as long as it belongs to the category of anions. For example, fluoride ion, chloride ion, bromide ion, iodide ion, sulfate ion, nitrate ion, phosphate ion, Examples include perchlorate ions, oxalate ions, citrate ions, succinate ions, tetrafluoroborate ions, hexafluorophosphate ions, and the like.

  Specific examples of the aliphatic salt include, for example, N, N-dimethyl-behenylamine hydrochloride, N-methyl-N-ethyl-behenylamine hydrochloride, N-methyl-Nn-propyl-behenylamine hydrochloride Salt, N, N-dioleyl-methylamine hydrochloride, N, N-dimethyl-behenylamine sulfate, N-methyl-N-ethyl-behenylamine sulfate, N-methyl-Nn-propyl-behenylamine sulfate Salts, aliphatic amine salts such as N, N-dioleyl-methylamine sulfate; P, P-dimethyl-behenylphosphine hydrochloride, P, P-diethyl-behenylphosphine hydrochloride, P, P-dipropyl-behenylphosphine hydrochloride Salt, P, P-dimethyl-behenylphosphine sulfate, P, P-diethyl-behenylphosphine sulfate, P, P-dipropyl-behenyl Sufin aliphatic phosphonium salts such as sulfates; and the like.

Further, the clay compound powder constituting the organically modified clay powder (B) may be any clay compound powder as long as it belongs to the category of clay compound powder, and generally a silica tetrahedron is continuous in two dimensions. A layer called a silicate layer, which is formed by combining 1: 1 or 2: 1 octahedral sheets in which the octahedral sheet and the alumina octahedron and magnesia octahedron are two-dimensionally continuous, overlaps each other. In some cases, Si in some tetrahedral tetrahedrons is replaced with Al, Al in alumina octahedrons is replaced with Mg, Mg in magnesia octahedrons is replaced with Li, etc. It has a negative charge, and it is known that cations such as Na ⁺ and Ca ²⁺ exist between layers in order to compensate for this negative charge. As the clay compound, kaolinite, talc, smectite, vermiculite, mica, brittle mica, curdstone and the like as natural products or synthetic products exist, and these can be used. Smectite is preferable from the viewpoint of easiness of modification and organic modification, and hectorite or montmorillonite is more preferable among smectites.

  The organically modified clay powder (B) can be obtained by introducing the aliphatic salt between layers of the clay compound powder to form an ionic complex. In preparing the organically modified clay powder (B), it is preferable to carry out the treatment by selecting conditions of a clay compound concentration of 0.1 to 30% by weight and a treatment temperature of 0 to 150 ° C. The aliphatic salt may be prepared as a solid and dissolved in a solvent for use, or a solution of the aliphatic salt may be prepared by a chemical reaction in the solvent and used as it is. Regarding the reaction amount ratio between the clay compound powder and the aliphatic salt, it is preferable to use an aliphatic salt having an equivalent amount or more with respect to exchangeable cations of the clay compound powder. Examples of the processing solvent include aliphatic hydrocarbons such as pentane, hexane and heptane; aromatic hydrocarbons such as benzene and toluene; alcohols such as ethyl alcohol and methyl alcohol; ethers such as ethyl ether and n-butyl ether. Halogenated hydrocarbons such as methylene chloride and chloroform; acetone; 1,4-dioxane; tetrahydrofuran; water; Preferably, alcohols or water is used alone or as one component of a solvent.

  In addition, as a method for controlling the median diameter of the organically modified clay powder (B) to 4 μm or more and 20 μm or less and the geometric standard deviation of the particle diameter to 0.15 or less, direct control is performed by pulverization or granulation. And a method of classifying after pulverization or granulation, etc., and direct control by granulation by spray drying is preferred. In addition, modification may be performed after particle size control, or particle size control may be performed after modification, and in particular, particle size control by spray drying is preferably performed before modification.

  The clay compound before modification becomes a colloidal liquid when dispersed in water, and a spherical clay compound powder can be obtained by spray-drying the colloidal liquid as it is.

  At that time, since the viscosity of the clay colloid liquid tends to increase and the gelation tends to occur at that time, the problem of difficulty in feeding and supplying to the spray dryer is likely to occur. It is preferred to add sodium and / or sodium etidronate. At that time, the addition amount of the anti-gelling agent is preferably 5% by weight or more and 20% by weight or less with respect to the clay compound because more effective prevention of gelation becomes possible. As a clay compound at that time, as a commercially available product in which an antigelling agent has been added to synthetic clay, for example, (trade name) Laponite RDS (manufactured by Big Chemie Japan Co., Ltd., sodium pyrophosphate is added to synthetic hectorite. Addition), (trade name) Laponite S482 (manufactured by Big Chemie Japan, Inc., sodium etidronate added to synthetic hectorite). Sodium pyrophosphate is gradually hydrolyzed in water to replace sodium phosphate, which has no anti-gelling effect, and is promoted particularly at high temperatures, but it is included because sodium etidronate is highly stable. It is possible to lower the viscosity by heating the clay colloid solution.

  On the other hand, since the modified clay compound is not colloidal even when dispersed in water, the organic modified clay compound slurry is pulverized by wet pulverization such as a ball mill, and the organic modified clay compound is made into fine particles of less than 1 μm and then spray-dried. Do. Since the viscosity of the organically modified clay compound slurry after the wet pulverization is remarkably increased, the slurry concentration is preferably 15% by weight or less.

  Examples of the spray drying method include a rotating disk type, a pressure nozzle type, a two-fluid nozzle type, and a four-fluid nozzle type, and any type is acceptable, but a rotating disk type that can easily narrow the particle size distribution is preferable. In the rotating disk type, colloidal liquid or slurry is dropped onto the disk that rotates at high speed and sprayed by the centrifugal force of the disk, so the size of the sprayed droplets varies depending on the disk diameter and the number of rotations, and is obtained by drying the droplets The particle size of the powder can be controlled.

The median diameter (d ₅₀ ) of the organically modified clay powder (B) is 4 μm or more and 20 μm or less, and the geometric standard deviation of the particle size is 0.15 or less. Here, the geometric standard deviation is an index indicating the spread of the particle size distribution defined by log (d ₈₄ / d ₅₀ ), and d ₈₄ is the particle size at which the integral curve of particle size is 84%. When the median diameter and standard deviation of the powder are within this range, the ultrahigh molecular weight polyethylene particles obtained by the catalyst of the present invention have excellent powder characteristics, and have a median diameter of 100 μm or more and 200 μm or less. It becomes possible to efficiently obtain ultra high molecular weight polyethylene particles having a deviation of 0.15 or less.

  The particle size of the organically modified clay powder (B) can be measured by a laser diffraction / scattering particle size measuring device.

  In addition, the organically modified clay powder (B) can be a catalyst for producing ultrahigh molecular weight polyethylene particles capable of efficiently producing ultrahigh molecular weight polyethylene particles having excellent particle size distribution, powder characteristics, and flow characteristics. Therefore, it is preferable that 90% or more of the organically modified clay powder having a circularity of 0.9 to 1 is contained. Here, the circularity is an index defined by (peripheral length of circles having the same projected area) / (peripheral length of particles), and the closer to 1, the closer to the circle. If the proportion of particles with a circularity of 1 is 100%, these particles can be considered as true spheres. The method for measuring the circularity is not particularly limited. For example, it can be obtained by taking an SEM photograph of particles or powder, projecting it on a very fine lattice, and measuring the lattice area of the projected portion and its outer periphery.

  In general, powders obtained by spray drying are often spherical or oblate, but in cases where the viscosity of the stock solution is high and the drying of the droplets does not proceed uniformly, the resulting powder has dents or holes in the center. In some cases, a powder having a circularity of less than 0.9 is formed. Further, since the powder obtained by a pulverization method such as a jet mill has an indefinite shape, the circularity tends to be less than 0.9.

  Any organoaluminum compound (C) constituting the ultra high molecular weight polyethylene particle production catalyst of the present invention can be used as long as it belongs to the category called organoaluminum compound. An organoaluminum compound represented by the following general formula (7) is preferable because it becomes a catalyst system capable of producing molecular weight ethylene polymer particles with high production efficiency. Here, when a compound other than the organoaluminum compound, such as a boron compound or a methylalumoxane compound, is used, the ethylene polymer obtained by the catalyst has a low molecular weight or is inferior in moldability. It has the subject of.

(In the formula, R ¹¹ is a hydrocarbon group having 1 to 20 carbon atoms, and R ¹² and R ¹³ are each independently a hydrocarbon group having 1 to 20 carbon atoms, a hydrogen atom, or a chlorine atom.)
Examples of the organoaluminum compound include alkylaluminums such as trimethylaluminum, triethylaluminum, and triisobutylaluminum because the transition metal compound (A) can be easily alkylated.

  A nonionic surfactant (D) may be added to the catalyst for producing ultrahigh molecular weight polyethylene particles of the present invention.

The nonionic surfactant (D) is a compound represented by the general formula (8). A, b and c are each an integer of 1 to 300 representing the average degree of polymerization, preferably a and c are each an integer of 1 to 60, b is an integer of 2 to 100, and the total molecular weight Is preferably 100 to 20000. M is 1 or 2, n is an integer of 3 to 20, and preferably m is 2 and n is 3.

  Specific examples of the nonionic surfactant (D) include polyoxymethylene polyoxypropylene glycol and polyoxyethylene polyoxypropylene glycol.

  When a nonionic surfactant (D) is added, the resulting ultrahigh molecular weight polyethylene particles are less likely to be charged, and it is possible to prevent fouling to the reactor and to prevent a decrease in fluidity due to electrostatic adhesion. Become.

  The transition metal compound (A) (hereinafter also referred to as component (A)) constituting the catalyst for producing ultrahigh molecular weight polyethylene particles of the present invention, the organically modified clay powder (B) (hereinafter referred to as component (B)). And the organoaluminum compound (C) (hereinafter also referred to as the component (C)), the component (A), the component (B) and the component (C) No limitation is imposed as long as it can be used as a catalyst for producing molecular weight polyethylene particles, and among them, a catalyst capable of producing ultra-high molecular weight polyethylene particles particularly efficiently can be obtained. The molar ratio of the component to the component (C) per metal atom is preferably in the range of (component (A)) :( component (C)) = 100: 1 to 1: 100000, and particularly 1: 1 to 1: 1. 100 It is preferably in the range of 0. The weight ratio of the component (A) to the component (B) is preferably ((A) component): ((B) component) = 10: 1 to 1: 10000, particularly 3: 1 to 1: 1000. It is preferable that it is the range of these.

  Further, the use ratio of the nonionic surfactant (D) (hereinafter sometimes referred to as the component (D)) is excellent in antistatic action and polymerization activity, so that the weight ratio of the component (B) to the component (D). Is preferably in the range of ((B) component): ((D) component) = 1: 0.0001 to 1: 100, particularly ((B) component): ((D) component) = 1: 0. A range of 0.01 to 20 is preferable.

  Regarding the method for preparing the catalyst for producing ultrahigh molecular weight polyethylene particles of the present invention, any method may be used as long as it can be prepared from the component (A), the component (B) and the component (C). . For example, there can be mentioned a method in which each of the components (A), (B) and (C) is mixed in an inert solvent or using a monomer for polymerization as a solvent. The order of reacting these components is not limited. However, since the polymerization activity is particularly excellent, after contacting the (B) component and the (C) component, the ultra-high height in which the (A) component is contacted. A catalyst for producing molecular weight polyethylene particles is preferred. There is no limitation on the temperature and processing time for performing the treatment at this time. It is also possible to prepare a catalyst system for producing ultrahigh molecular weight polyethylene particles by using two or more of each of component (A), component (B), and component (C).

  Ultra high molecular weight polyethylene particles obtained using the catalyst for producing ultra high molecular weight polyethylene particles of the present invention may be not only ethylene homopolymer particles but also copolymer particles with other α-olefins. The ultrahigh molecular weight polyethylene particles obtained by polymerization are used in the sense of including not only homopolymer particles but also copolymer particles.

  Examples of the method for producing the ultrahigh molecular weight polyethylene particles of the present invention include a slurry polymerization method. The solvent used in the slurry polymerization method may be any organic solvent that is generally used, and examples thereof include benzene, toluene, xylene, pentane, hexane, heptane, and the like. Propylene, 1-butene, 1- Olefins such as octene and 1-hexene can also be used as a solvent.

  Examples of the α-olefin used for copolymerization with ethylene when making polyethylene a copolymer include α- such as propylene, 1-butene, 4-methyl-1-pentene, 1-hexene and 1-octene. Mention may be made of olefins.

  The polymerization conditions such as polymerization temperature, polymerization time, polymerization pressure, and monomer concentration when producing the ultra high molecular weight polyethylene particles of the present invention can be arbitrarily selected, and among them, the ultra high molecular weight polyethylene particles are efficiently produced. Therefore, the polymerization temperature is preferably 30 to 90 ° C., the polymerization time is 10 seconds to 20 hours, and the polymerization pressure is normal pressure to 100 MPa. It is also possible to adjust the molecular weight using hydrogen during polymerization. The polymerization can be carried out by any of batch, semi-continuous and continuous methods, and can be carried out in two or more stages by changing the polymerization conditions. Further, the ultra-high molecular weight polyethylene particles obtained after completion of the polymerization can be obtained by separating and recovering from the polymerization solvent by a conventionally known method and drying.

  Since the ultra high molecular weight polyethylene particles of the present invention become ultra high molecular polyethylene particles having excellent particle size distribution, powder characteristics, and flow characteristics, particles having a circularity of 0.9 to 1 account for 90% or more, and the median diameter is The intrinsic viscosity (dL / g) measured at 135 ° C. using decalin as a solvent is preferably 10 or more and less than 60.

  Further, the ultra high molecular weight polyethylene particles are particularly excellent in flow characteristics and processability, and therefore the geometric standard deviation of the particle diameter is preferably 0.15 or less.

  The circularity, median diameter, and geometric standard deviation can be obtained by the same method as described above.

  Since the ultra high molecular weight polyethylene particles of the present invention are excellent in molding processability and mechanical properties, the ratio of weight average molecular weight to number average molecular weight (weight average molecular weight / number average molecular weight) exceeds 2.0. It is preferably 0 or less, more preferably 2.0 to 4.0 or less, and particularly preferably 3.0 to 4.0 or less.

  The ultra high molecular weight polyethylene particles preferably have a repose angle of 40 ° or less because they have excellent flow characteristics and moldability. The angle of repose measurement method is an injection method that measures the angle that particles form when they are naturally dropped and deposited on a horizontal surface, and the angle that particles that are left in the container make by naturally dropping from a small hole at the bottom of the container. There are cases where the angle of repose is different and there are cases where the angle of repose is different. Point to the corner.

  The catalyst for producing ultrahigh molecular weight polyethylene particles of the present invention is excellent in fluidity, and can efficiently produce ultrahigh molecular weight polyethylene particles having excellent mechanical properties, wear resistance, and moldability. Ultra high molecular weight polyethylene particles can be used as materials for various molded articles.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Unless otherwise noted, the reagents used were commercially available products or those synthesized according to known methods.

Three types of spray dryers (trade name: L-8i (small atomizer type) manufactured by Okawara Chemical Co., Ltd.) and (trade name) SDR-27 (large size atomizer type) manufactured by IS Japan Co., Ltd. are used to adjust the particle size of clay. ) And Fujisaki Electric Co., Ltd. (trade name) MDL-050M (four-fluid nozzle type)), and if necessary, an airflow classifier (Nisshin Engineering Co., Ltd. (trade name) TC -15). The particle size after pulverization was measured using a microtrack particle size distribution measuring apparatus (manufactured by Nikkiso Co., Ltd., (trade name) MT3000) using ethanol as a dispersant, and a cumulative 50% diameter (d ₅₀ , median diameter) on a volume basis. And 84% diameter (d ₈₄ ) was determined, and log (d ₈₄ / d ₅₀ ) was taken as the geometric standard deviation (σ).

  Preparation of the catalyst for producing ultrahigh molecular weight polyethylene particles, production of ultrahigh molecular weight polyethylene particles, and solvent purification were all carried out in an inert gas atmosphere. A hexane solution (20 wt%) of triisobutylaluminum manufactured by Tosoh Finechem Co., Ltd. was used.

  Furthermore, various physical properties of the ultrahigh molecular weight polyethylene particles in the examples were measured by the following methods.

~ Measurement of circularity ~
Using a FE-SEM JSM-7100F manufactured by JEOL Ltd., a transparent graph paper with an interval of 0.5 mm was overlaid on the SEM photo that was osmium-coated on the surface and copied at a magnification of 2000, and the grid of the graph paper on which particles overlapped was painted. It was determined by measuring the lattice area and the outer diameter.

~ Measurement of intrinsic viscosity ~
Using an Ubbelohde viscometer, measurement was performed at 135 ° C. using decalin as a solvent at an ultrahigh molecular weight polyethylene particle concentration of 0.005 wt% to 0.01 wt%.

~ Measurement of Mw, Mn and Mw / Mn ~
Using a GPC device (manufactured by Tosoh Corporation, (trade name) HLC-8121GPC / HT) and a column (manufactured by Tosoh Corporation, (trade name) TSKgel GMHhr-H (20) HT), the column temperature was set to 140 ° C. Set and measured using 1,2,4-trichlorobenzene as eluent. A measurement sample was prepared at a concentration of 1.0 mg / mL, and 0.3 mL was injected and measured. The calibration curve of molecular weight was calibrated using a polystyrene sample having a known molecular weight. In addition, Mw and Mn were calculated | required as a value of linear polyethylene conversion.

-Median diameter and geometric standard deviation of ultra high molecular weight polyethylene particles-
Ultra high molecular weight polyethylene particles are classified according to the sieves defined in JIS Z8801 (openings: 710 μm, 500 μm, 425 μm, 300 μm, 212 μm, 150 μm, 106 μm, 75 μm, 53 μm), and the weight of the particles on each sieve and the sieve mesh An integral curve of particle weight-particle diameter showing a correlation with the opening was used, and the particle diameter of 50% by weight in the integral curve was defined as the median diameter. Furthermore, the log (d ₈₄ / d ₅₀ ) was defined as the geometric standard deviation (σ) based on the particle diameter d ₅₀ of 50 wt% and the particle diameter d ₈₄ of 84 wt% in the integral curve.

~The bulk density~
It measured according to JIS K-6721: 1997.

~ Melting point measurement ~
Using DSC (manufactured by Hitachi High-Tech Science Co., Ltd., (trade name) DSC6220), α-alumina was used as a reference, 30 ° C was the start temperature, the sample was heated to 220 ° C at a temperature increase rate of 10 ° C / min, The temperature was measured while cooling to −20 ° C. and increasing the temperature again at a temperature increase rate of 10 ° C./min.

~ Measurement of fluidity ~
It was carried out by an injection method in which 50 g of polyethylene particles were placed in a hopper, allowed to fall naturally, and the angle formed by the powder when it was deposited on a horizontal surface.

-Preparation of ultra high molecular weight polyethylene evaluation sheet-
The evaluation sheet of ultra high molecular weight polyethylene was molded by the following method. That is, ultra high molecular weight polyethylene was sandwiched between polyethylene terephthalate films, preheated at 190 ° C. for 5 minutes, and then heat-rolled under conditions of 190 ° C. and a press pressure of 20 MPa. Thereafter, the mold was cooled at a mold temperature of 110 ° C. for 10 minutes to prepare a press sheet having a thickness of 0.3 mm.

~ Measurement of tensile strength at break ~
A sample cut from a sheet for evaluation of ultrahigh molecular weight polyethylene into a dumbbell shape (measurement part width 5 mm) was allowed to stand at 23 ° C. for 48 hours, and then a tensile tester (manufactured by A & D Co., Ltd., ( (Trade name) Tensilon RTG-1210) was subjected to a tensile test at a measurement temperature of 23 ° C., an initial length of the test piece of 20 mm, and a tensile speed of 20 mm / min to obtain a tensile breaking strength.

Example 1
(1) Granulation of clay powder 0.8 kg of synthetic hectorite (manufactured by Big Chemie Japan Co., Ltd., (trade name) Laponite RDS) is dispersed in 19.2 kg of water and stirred for 4 hours to give a colorless and transparent clay colloidal solution. Obtained. When 2.5 kg of this colloidal liquid was fed to a small atomizer type spray dryer equipped with a rotating disk having a diameter of 40 mm per hour and spray-dried at a disk rotating speed of 29,500 rpm and hot air inlet temperature of 250 ° C. 7 kg of clay powder was obtained. The median diameter of this clay powder was 7.6 μm, and the geometric standard deviation was 0.12. Further, when the circularity was measured from the SEM photograph, the ratio of particles having a circularity of 0.9 to 1 was 95%.

(2) Modification of clay powder Into a 2 liter container, 0.6 liter of industrial alcohol (manufactured by Nippon Alcohol Sales Co., Ltd., (trade name) Echinen F-3) and 0.6 liter of distilled water were added, and 1.5 g of concentrated hydrochloric acid And dimethylbehenylamine; 84.8 g (0.24 mol) of C ₂₂ H ₄₅ (CH ₃ ) ₂ N (manufactured by Lion Corporation, (trade name) Armin DM22D), and heated to 45 ° C. (1) After 0.2 kg of the obtained clay powder was dispersed, the mixture was heated to 60 ° C. and stirred for 1 hour while maintaining the temperature. This slurry was separated by filtration, washed twice with 120 ml of water at 60 ° C., and dried in an oven at 85 ° C. for 12 hours to obtain 0.28 kg of an organically modified clay powder. This organically modified clay powder had a median diameter of 8.4 μm, a standard deviation of 0.13, and a ratio of circularity of 0.9 to 1 of 94%.

(3) Preparation of catalyst suspension for production of ultra-high molecular weight polyethylene After replacing a nitrogen flask in a 500 ml flask equipped with a thermometer and a reflux tube, 50 ml of the organically modified clay powder obtained in (2) and 140 ml of hexane were obtained. Then, 1.2 g of diphenylmethylene (cyclopentadienyl) (2- (dimethylamino) -9-fluorenyl) zirconium dichloride and 280 ml of 20% triisobutylaluminum in hexane were added thereto at 60 ° C. for 3 hours. Stir. After standing for 1 hour, the supernatant liquid is extracted, washed twice with 420 ml of hexane, 420 ml of hexane and a hexane solution of 20% triisobutylaluminum are added, and a suspension of the catalyst for producing ultrahigh molecular weight polyethylene particles is prepared. Obtained (solid weight: 15.7 wt%).

(4) Production of ultrahigh molecular weight polyethylene particles 1.2 liters of hexane and 1.1 ml of a 20% triisobutylaluminum hexane solution were added to a 2-liter autoclave purged with nitrogen, and stirred at 25 ° C. for 30 minutes. 127 mg (equivalent to 20 mg solid content) of the suspension of the catalyst for producing ultrahigh molecular weight polyethylene particles obtained in (3) was added, and the partial pressure was 0.87 MPa while adjusting the temperature in the autoclave to maintain 60 ° C. Then, ethylene was continuously fed to carry out slurry polymerization of ethylene. After 240 minutes, depressurization and cooling were performed, and the slurry was filtered and dried to obtain 120 g of ultrahigh molecular weight polyethylene particles.

The ultra high molecular weight polyethylene particles have a circularity of 0.9 to 1 and a total particle number of 94%, a median diameter of 124 μm, σ of 0.13, a melting point of 135 ° C., an intrinsic viscosity of 22 dL / g, Mw / Mn was 3.7, the bulk density was 396 kg / m ³ , and the angle of repose was 38.3 °. Further, the tensile breaking strength of the molded sheet was 55 MPa.

Example 2
(1) Granulation of clay powder It carried out similarly to (1) of Example 1.

(2) Modification of clay powder Into a 2 liter container, 0.6 liter of industrial alcohol (manufactured by Nippon Alcohol Sales Co., Ltd., (trade name) Echinen F-3) and 0.6 liter of distilled water are added, and 1.5 g of concentrated hydrochloric acid is added. And (C ₁₈ H ₃₅ ) ₂ CH ₃ N (manufactured by Lion Corporation, (trade name) Armin M2O) 127 g (0.24 mol) are added, heated to 45 ° C., and the previous spray drying is performed. After 200 g of the clay powder was dispersed, the temperature was raised to 60 ° C. and stirred for 1 hour while maintaining the temperature. The slurry was separated by filtration, washed twice with 120 ml of water at 60 ° C., and dried in an oven at 85 ° C. for 12 hours to obtain 320 g of an organically modified clay powder. This organically modified clay powder had a median diameter of 8.5 μm, a geometric standard deviation of 0.14, and a ratio of circularity of 0.9 to 1 was 91%.

(3) Preparation of catalyst suspension for producing ultra-high molecular weight polyethylene particles After substituting a 5-liter flask equipped with a thermometer and a reflux tube with nitrogen, 50 g of the organically modified clay powder obtained in (2) and 140 hexane were added. Next, 1.57 g of diphenylmethylene (cyclopentadienyl) (2- (diethylamino) -9-fluorenyl) hafnium dichloride and 280 ml of 20% triisobutylaluminum in hexane were added to the mixture at 60 ° C. for 3 hours. Stir. After standing for 1 hour, the supernatant was extracted, washed twice with 420 ml of hexane, and then added with 420 ml of hexane and a hexane solution of 20% triisobutylaluminum to obtain a suspension of a metallocene catalyst (solid weight). Min: 15.9 wt%).

(4) Production of ultrahigh molecular weight polyethylene particles 1.2 liters of hexane and 1.1 ml of a 20% triisobutylaluminum hexane solution were added to a 2-liter autoclave purged with nitrogen, and stirred at 25 ° C. for 30 minutes. Add 1.54 g (equivalent to 245 mg solids) of the suspension of the catalyst for producing ultrahigh molecular weight polyethylene particles obtained in (3) and 7.9 g of 1-butene so that the temperature in the autoclave is kept at 60 ° C. While adjusting, ethylene was continuously supplied so that the partial pressure was 0.87 MPa, and slurry polymerization of ethylene was performed. After 145 minutes, depressurization and cooling were performed, and the slurry was filtered and dried to obtain 207 g of ultrahigh molecular weight polyethylene particles.

The ultrahigh molecular weight polyethylene particles have a circularity of 0.9 to 1 and a total number of particles of 92%, a median diameter of 121 μm, σ of 0.11, a melting point of 121 ° C., an intrinsic viscosity of 17 dL / g, Mw / Mn was 3.9, the bulk density was 430 kg / m ³ , the angle of repose was 39.3 °, and the tensile strength at break of the molded sheet was 37 MPa.

Example 3
(1) Granulation of clay powder It carried out similarly to (1) of Example 1.

(2) Modification of clay powder The same procedure as in (2) of Example 2 was performed.

(3) Preparation of catalyst suspension for production of ultrahigh molecular weight polyethylene particles The same procedure as in (2) of Example 2 was performed.

(4) Production of ultrahigh molecular weight polyethylene particles 1.2 liters of hexane and 1.1 ml of a 20% triisobutylaluminum hexane solution were added to a 2-liter autoclave purged with nitrogen, and stirred at 25 ° C. for 30 minutes. 1.54 g (corresponding to a solid content of 245 mg) of the suspension of the ultrahigh molecular weight polyethylene particle production catalyst obtained in (3), polyoxyethylene polyoxypropylene glycol (Daiichi Kogyo Seiyaku Co., Ltd., (trade name) Epan 710) 15.8 mg and 1-butene 7.9 g were added, ethylene was continuously supplied so that the partial pressure was 0.87 MPa while adjusting the temperature in the autoclave to be 60 ° C. The slurry polymerization was performed. After 145 minutes, depressurization and cooling were performed, and the slurry was filtered and dried to obtain 201 g of ultrahigh molecular weight polyethylene particles.

The ultra high molecular weight polyethylene particles have a circularity of 0.9 to 1 and a total number of particles of 91%, a median diameter of 122 μm, σ of 0.11, a melting point of 121 ° C., an intrinsic viscosity of 17 dL / g, Mw / Mn was 3.9, the bulk density was 435 kg / m ³ , and the angle of repose was 35.7 °. Further, the tensile breaking strength of the molded sheet was 37 MPa.

Example 4
(1) Granulation and classification of clay powder 52.2 kg of synthetic hectorite (BIC Chemie Japan Co., Ltd., (trade name) Laponite RDS) containing sodium pyrophosphate as an anti-gelling agent was dispersed in 747.8 kg of water, The mixture was stirred for 4 hours to obtain a colorless and transparent clay colloid solution. When 149 kg of this colloidal solution was sent to a large atomizer spray dryer per hour and spray-dried at a rotational speed of a disk with a diameter of 150 mm at 24,000 rpm and hot air inlet temperature of 300 ° C., 44.4 kg of clay powder was obtained. The median diameter of this clay powder was 11.4 μm, and the geometric standard deviation was 0.21. The obtained clay powder was supplied to an airflow classifier at 20 kg / hr and classified at an air volume of 7.5 m ³ / min and a rotational speed of 2550 rpm. As a result, the median diameter was 7.1 μm and the geometric standard deviation was 0.13. 13.2 kg of clay powder was obtained. The ratio of the circularity of 0.9 to 1 was 92%.

(2) Modification of clay powder Into a 1 liter container, 300 ml of industrial alcohol (manufactured by Japan Alcohol Sales Co., Ltd., (trade name) Echinen F-3) and 300 ml of distilled water are placed, 13 ml of concentrated hydrochloric acid and methylbehenylamine; 44.9 g (0.12 mol) of C ₂₂ H ₄₅ (CH ₃ ) ₂ N (manufactured by Lion Corporation, (trade name) Armin DM22D) is added, heated to 45 ° C., and obtained by the previous spray drying and classification. After 100 g of the obtained clay powder was dispersed, the temperature was raised to 60 ° C. and stirred for 1 hour while maintaining the temperature. This slurry was filtered, washed twice with 60 liters of water at 60 ° C., and dried in an oven at 85 ° C. for 12 hours to obtain 136 g of an organically modified clay powder. This organically modified clay powder had a median diameter of 8.4 μm, a geometric standard deviation of 0.13, and a ratio of circularity of 0.9 to 1 was 92%.

(3) Preparation of catalyst suspension for production of ultra high molecular weight polyethylene particles 15 g of the organically modified clay powder obtained in (2) after substituting a 300 ml four-necked flask equipped with a thermometer and a reflux tube with nitrogen, Add 65 ml of hexane, then add 0.429 g of diphenylmethylene (cyclopentadienyl) (2- (diethylamino) -9-fluorenyl) hafnium dichloride, and 85 ml of 20% triisobutylaluminum in hexane to add 60 ° C. For 3 hours. After standing for 1 hour, the supernatant was extracted, washed twice with 125 ml of hexane, and then added with 125 ml of hexane and 6 ml of a 20% triisobutylaluminum hexane solution to obtain a suspension of a metallocene catalyst ( Solid weight: 12.2 wt%).

(4) Production of ultra high molecular weight polyethylene particles 6 liters of hexane and 5.5 ml of hexane solution of 20% triisobutylaluminum were added to a 10 liter autoclave purged with nitrogen, and stirred at 25 ° C. for 10 minutes. 3.17 g of the suspension for producing ultra-high molecular weight polyethylene particles obtained in (1) (corresponding to a solid content of 387 mg) was added, and the partial pressure was 0.87 MPa while adjusting the temperature in the autoclave to be 60 ° C. Then, ethylene was continuously fed to carry out slurry polymerization of ethylene. After 240 minutes, depressurization and cooling were performed, and the slurry was filtered and dried to obtain 1918 g of ultrahigh molecular weight polyethylene particles.

The ultra high molecular weight polyethylene particles have a circularity of 0.9 to 1 and a total number of particles of 93%, a median diameter of 172 μm, σ of 0.12, a melting point of 134 ° C., and an intrinsic viscosity of 18.5 dL / g, Mw / Mn was 3.8, bulk density was 412 kg / m ³ , angle of repose was 38.1 °, and tensile strength at break of the molded sheet was 51 MPa.

Example 5
(1) Granulation of clay powder 3 kg of synthetic hectorite (Bicchemy Japan Co., Ltd., (trade name) Laponite S482) to which sodium etidronate was added was dispersed in 7 kg of water and stirred at 60 ° C for 3 hours. A thin and cloudy clay colloidal solution was obtained. This colloidal solution was fed into a four-fluid nozzle spray dryer at a rate of 1.2 kg per hour and spray dried at a hot air inlet temperature of 200 ° C. to obtain 2.7 kg of clay powder. This clay powder had a median diameter of 6.2 μm, a geometric standard deviation of 0.21, and a ratio of circularity of 0.9 to 1 was 93%.

(2) Modification of clay powder 150 ml of ethanol and 150 ml of distilled water were placed in a 500 ml container, and 6.7 ml of concentrated hydrochloric acid and methylbehenylamine; C ₂₂ H ₄₅ (CH ₃ ) ₂ N (manufactured by Lion Corporation, (Product name) Armin DM22D) 22.5 g was added and heated to 45 ° C., 50 g of the clay powder obtained by the previous spray drying and classification was dispersed, and then the temperature was raised to 60 ° C. Stirring was continued for 1 hour. This slurry was filtered, washed twice with 60 liters of water at 60 ° C., and dried in an oven at 85 ° C. for 12 hours to obtain 68 g of an organically modified clay powder. This organically modified clay powder had a median diameter of 7.5 μm, a standard deviation of 0.10, and a ratio of circularity of 0.9 to 1 was 93%.

(3) Preparation of catalyst suspension for production of ultra high molecular weight polyethylene particles 30 g of the organically modified clay powder obtained in (2) after substituting a 500 ml four-necked flask equipped with a thermometer and a reflux tube with nitrogen Add 130 ml of hexane, then add 0.858 g of diphenylmethylene (cyclopentadienyl) (2- (diethylamino) -9-fluorenyl) hafnium dichloride and 170 ml of 20% triisobutylaluminum in hexane at 60 ° C. For 3 hours. After standing for 1 hour, the supernatant was extracted, washed twice with 125 ml of hexane, and then added with 125 ml of hexane and 6 ml of a 20% triisobutylaluminum hexane solution to obtain a suspension of a metallocene catalyst ( Solid weight: 12.2 wt%).

(4) Production of ultra-high molecular weight polyethylene particles 1.2 liters of hexane and 1.1 ml of a 20% triisobutylaluminum hexane solution were added to a 2-liter autoclave purged with nitrogen, and stirred at 25 ° C. for 10 minutes. 639 mg (equivalent to 78 mg solid content) of the suspension of the catalyst for producing ultrahigh molecular weight polyethylene particles obtained in (3) was added, and the partial pressure was 0.67 MPa while adjusting the temperature in the autoclave to maintain 60 ° C. Then, ethylene was continuously fed to carry out slurry polymerization of ethylene. After 180 minutes, depressurization and cooling were performed, and the slurry was filtered and dried to obtain 152 g of ultrahigh molecular weight polyethylene particles.

The ultra high molecular weight polyethylene particles have a circularity of 0.9 to 1 and a total number of particles of 92%, a median diameter of 156 μm, σ of 0.09, a melting point of 134 ° C., and an intrinsic viscosity of 18.4 dL / g, Mw / Mn was 3.8, the bulk density was 403 kg / m ³ , the repose angle was 39.1 °, and the tensile strength at break of the molded sheet was 52 MPa.

Comparative Example 1
(1) Granulation of clay powder Synthetic hectorite (manufactured by Big Chemie Japan Co., Ltd., (trade name) Laponite RDS) 2.6 kg is dispersed in 17.4 kg of water and stirred for 4 hours to give a colorless and transparent clay colloidal solution. Obtained. When 2.5 kg of this colloidal solution was fed to a small atomizer spray dryer equipped with a rotating disk having a diameter of 40 mm per hour and spray-dried at a disk rotation speed of 20,000 rpm and hot air inlet temperature of 250 ° C. 4 kg of clay powder was obtained. The median diameter of this clay powder was 25 μm, and the geometric standard deviation was 0.21. Moreover, when the circularity was measured from the SEM photograph, the ratio of the circularity of 0.9 to 1 was 92%.

(2) Modification of clay powder 0.6 liters of industrial alcohol and 0.6 liters of distilled water are placed in a 2 liter container, and 1.5 g of concentrated hydrochloric acid and methyldioleylamine; (C ₁₈ H ₃₅ ) ₂ CH ₃ N ( Add 127 g (0.24 mol) of (trade name) Armin M2O, manufactured by Lion Co., Ltd., heat to 45 ° C, disperse 200 g of the spray-dried clay powder, and then raise the temperature to 60 ° C. The mixture was stirred for 1 hour while maintaining the temperature. The slurry was separated by filtration, washed twice with 120 ml of water at 60 ° C., and dried in an oven at 85 ° C. for 12 hours to obtain 324 g of an organically modified clay powder. This organically modified clay powder had a median diameter of 26 μm, a geometric standard deviation of 0.22, and a ratio of particles having a circularity of 0.9 to 1 of 91%.

(3) Preparation of catalyst suspension for polyethylene production After replacing a nitrogen of a 5 liter flask equipped with a thermometer and a reflux tube, 50 g of the organically modified clay powder obtained in (2) and 140 ml of hexane were added. 1.57 g of diphenylmethylene (cyclopentadienyl) (2- (diethylamino) -9-fluorenyl) hafnium dichloride and 280 ml of 20% triisobutylaluminum in hexane were added and stirred at 60 ° C. for 3 hours. After standing for 1 hour, the supernatant was extracted, washed twice with 420 ml of hexane, and then added with 420 ml of hexane and a 20% triisobutylaluminum hexane solution to obtain a suspension of a catalyst for producing polyethylene (solid Weight: 15.9 wt%).

(4) Production of Ultra High Molecular Weight Polyethylene 1.2 liters of hexane and 1.1 ml of 20% triisobutylaluminum hexane solution were added to a 2 liter autoclave purged with nitrogen and stirred at 25 ° C. for 30 minutes. While adding 1.54 g (corresponding to a solid content of 245 mg) of the suspension for the catalyst for polyethylene production obtained in 3) and 7.9 g of 1-butene, adjusting the temperature in the autoclave to maintain 60 ° C, Ethylene was continuously supplied so that the pressure was 0.87 MPa, and slurry polymerization of ethylene was performed. After 145 minutes, depressurization and cooling were performed, and the slurry was filtered and dried to obtain 87 g of ultrahigh molecular weight polyethylene.

This ultrahigh molecular weight polyethylene has a circularity of 0.9 to 1 and a total number of particles of 80%, a median diameter of 210 μm, σ of 0.22, a melting point of 122 ° C., and an intrinsic viscosity of 16.5 dL / g. , Mw / Mn was 3.8, bulk density was 250 kg / m ³ , and repose angle was 47.7 °. Further, the tensile breaking strength of the molded sheet was 20 MPa.

Comparative Example 2
(1) Adjustment of particle size of clay powder 10 g of synthetic hectorite (manufactured by Big Chemie Japan Co., Ltd., (trade name) Laponite RDS) in a jet mill (manufactured by Seishin Enterprise Co., Ltd., (trade name) CO-JET SYSTEM α MARK III) / Min and pulverized with a 0.7 MPa nitrogen stream to obtain a clay powder having a median diameter of 3.1 μm and a standard deviation of 0.16. In this powder, 81% of particles having a circularity of 0.9 to 1 were present.

(2) Modification of clay powder 0.6 liters of industrial alcohol and 0.6 liters of distilled water are placed in a 2 liter container, and 1.5 g of concentrated hydrochloric acid and methyldioleylamine; (C ₁₈ H ₃₅ ) ₂ CH ₃ N ( Add 127 g (0.24 mol) of (trade name) Armin M2O, manufactured by Lion Co., Ltd., heat to 45 ° C, disperse 200 g of the spray-dried clay powder, and then raise the temperature to 60 ° C. The mixture was stirred for 1 hour while maintaining the temperature. The slurry was filtered, washed twice with 120 ml of water at 60 ° C., and dried in an oven at 85 ° C. for 12 hours to obtain 325 g of an organically modified clay powder. This organically modified clay powder had a median diameter of 3.8 μm, a geometric standard deviation of 0.17, and a ratio of particles having a circularity of 0.9 to 1 was 81%.

(3) Preparation of catalyst suspension for polyethylene production After replacing a nitrogen of a 5 liter flask equipped with a thermometer and a reflux tube, 50 g of the organically modified clay powder obtained in (2) and 140 ml of hexane were added. 1.57 g of diphenylmethylene (cyclopentadienyl) (2- (diethylamino) -9-fluorenyl) hafnium dichloride and 280 ml of 20% triisobutylaluminum in hexane were added and stirred at 60 ° C. for 3 hours. After standing for 1 hour, the supernatant was extracted, washed twice with 420 ml of hexane, and then added with 420 ml of hexane and a 20% triisobutylaluminum hexane solution to obtain a suspension of a catalyst for producing polyethylene (solid Weight: 15.9 wt%).

(4) Production of Ultra High Molecular Weight Polyethylene 1.2 liters of hexane and 1.1 ml of 20% triisobutylaluminum hexane solution were added to a 2 liter autoclave purged with nitrogen and stirred at 25 ° C. for 30 minutes. While adding 1.54 g (corresponding to a solid content of 245 mg) of the suspension for the catalyst for polyethylene production obtained in 3) and 7.9 g of 1-butene, adjusting the temperature in the autoclave to maintain 60 ° C, Ethylene was continuously supplied so that the pressure was 0.87 MPa, and slurry polymerization of ethylene was performed. After 145 minutes, depressurization and cooling were performed, and the slurry was filtered and dried to obtain 204 g of ultrahigh molecular weight polyethylene.

This ultra high molecular weight polyethylene has a circularity of 0.9 to 1 and the total number of particles is 89%, the median diameter is 110 μm, σ is 0.17, the melting point is 120 ° C., the intrinsic viscosity is 13 dL / g, Mw / Mn was 4.5, the bulk density was 380 kg / m ³ , and the angle of repose was 44.7 °. Further, the tensile breaking strength of the molded sheet was 22 MPa.

  Ultra high molecular weight polyethylene particles obtained from the catalyst for producing ultra high molecular weight polyethylene particles of the present invention have excellent fluidity, mechanical properties, wear resistance, and moldability, and are used as materials for various molded products. Can do.

Claims (7)

Transition metal compound (A) represented by the following general formula (1),

[Wherein, M ¹ is a titanium atom, a zirconium atom or a hafnium atom, and X is independently a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, carbon An alkylamino group having 1 to 20 carbon atoms, an alkylsilyl group having 1 to 20 carbon atoms, a substituent having oxygen introduced between carbon-carbon bonds of a hydrocarbon group having 1 to 20 carbon atoms, carbonization having 1 to 20 carbon atoms A substituent in which a part of the hydrogen group is substituted with an alkylamino group having 1 to 20 carbon atoms, a substituent in which a part of carbons in the hydrocarbon group having 1 to 20 carbon atoms is substituted with silicon, and R ¹ is A cyclopentadienyl group represented by formula (2);

(In the formula, each R ⁴ independently represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an alkylsilyl group having 1 to 20 carbon atoms, or 1 carbon atom. A substituent in which oxygen is introduced between the carbon-carbon bonds of a hydrocarbon group having ˜20, a substituent in which a part of the hydrocarbon group having 1 to 20 carbon atoms is substituted with an alkylamino group having 1 to 20 carbon atoms, carbon (This is a substituent obtained by substituting a part of carbons of the hydrocarbon group of 1 to 20 with silicon.)
R ² is a fluorenyl group having two amino groups represented by the following general formula (3),

(Wherein R ⁵ and R ⁶ are each independently a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 30 carbon atoms, C1-C20 arylalkylamino group, C1-C20 alkyl silyl group, C1-C20 hydrocarbon group, the substituent which introduce | transduced oxygen between the carbon-carbon bonds, C1-C20 A substituent obtained by substituting a part of the hydrocarbon group with an alkylamino group having 1 to 20 carbon atoms, a part of the hydrocarbon group having 1 to 20 carbon atoms substituted with silicon, and a substituent of R ⁵ Any one and / or any one of R ⁶ is an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 30 carbon atoms, or an arylalkylamino group having 7 to 30 carbon atoms.)
R ³ is a crosslinking unit of R ¹ and R ² represented by the following general formula (4) or the following general formula (5),

(In the formula, each R ⁷ independently represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 30 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, or 1 to 1 carbon atoms. 20 alkylsilyl groups, substituents in which oxygen is introduced between the carbon-carbon bonds of hydrocarbon groups having 1 to 20 carbon atoms, and some of the hydrocarbon groups having 1 to 20 carbon atoms are alkyl groups having 1 to 20 carbon atoms. A substituent substituted with an amino group, a substituent obtained by substituting a part of carbons of a hydrocarbon group having 1 to 20 carbon atoms with silicon, and M ² is a silicon atom, a germanium atom or a tin atom.)
n is an integer of 1-5. ]
Modified with an aliphatic salt represented by the following general formula (6), an organically modified clay powder (B) having a median diameter of 4 μm to 20 μm and a geometric standard deviation of particle diameter of 0.15 or less,

(Wherein R ^{8 to} R ¹⁰ are each independently an alkyl group having 1 to 30 carbon atoms, an alkyl alkoxy group having 1 to 30 carbon atoms, an alkylamino group having 1 to 30 carbon atoms, and an alkyl having 1 to 30 carbon atoms. A silyl group, a substituent in which oxygen is introduced between carbon-carbon bonds of the alkyl group having 1 to 30 carbon atoms, and a part of the alkyl group having 1 to 30 carbon atoms to an alkylamino group having 1 to 30 carbon atoms. A substituted substituent, a substituent obtained by substituting a part of carbons of the alkyl group having 1 to 30 carbon atoms with silicon, and at least one of R ^{8 to} R ¹⁰ is an alkyl group having 10 or more carbon atoms; M ³ is an atom of Group 15 of the periodic table, and [A ⁻ ] is an anion).
And a catalyst for producing ultrahigh molecular weight polyethylene particles, comprising an organoaluminum compound (C). The catalyst for producing ultrahigh molecular weight polyethylene particles according to claim 1, wherein the organically modified clay powder (B) contains 90% or more of an organically modified clay powder having a circularity of 0.9 to 1. The catalyst for producing ultrahigh molecular weight polyethylene particles according to claim 1 or 2, wherein the organically modified clay powder (B) contains sodium pyrophosphate and / or etidronate sodium. Particles with a circularity of 0.9 to 1 account for 90% or more, the median diameter is 100 μm or more and 200 μm or less, the geometric standard deviation of the particle diameter is 0.15 or less, and measured at 135 ° C. using decalin as a solvent. An ultrahigh molecular weight polyethylene particle having an intrinsic viscosity (dL / g) of 10 or more and less than 60. The ultrahigh molecular weight polyethylene particle according to claim 4, wherein the repose angle measured by an injection method for measuring an angle formed by the particle when it is naturally dropped and deposited on a horizontal surface is 40 ° or less. The ultrahigh molecular weight polyethylene particles according to claim 4 or 5, wherein the molecular weight distribution is more than 3.0 and not more than 4.0. A process for producing ultrahigh molecular weight polyethylene particles, wherein ethylene is homopolymerized or copolymerized in the presence of the catalyst for producing ultrahigh molecular weight polyethylene particles according to claim 1.