JP6521027B2 - Ultra-high molecular weight polyethylene copolymer - Google Patents

Description

  The present invention relates to an ultra-high molecular weight polyethylene copolymer exhibiting a high melting point and exhibiting high crystallinity, and a molded product obtained from the ultra-high molecular weight polyethylene copolymer, and more specifically, having a high melting point and a high crystallinity The present invention relates to a novel ultrahigh molecular weight polyethylene copolymer capable of providing a molded article having excellent mechanical strength, heat resistance and abrasion resistance, as well as a molded article formed therefrom.

  Conventionally, ultra-high molecular weight polyethylene is superior to general-purpose polyethylene in impact resistance, self-lubricity, abrasion resistance, sliding properties, weatherability, chemical resistance, dimensional stability, etc., and is comparable to engineering plastics. It is known to have physical properties.

  However, ultrahigh molecular weight polyethylene, due to its high molecular weight, has low fluidity in the melt and is difficult to form by kneading extrusion like ordinary polyethylene whose molecular weight is in the range of several tens of thousands to about half a million. Therefore, ultra-high-molecular-weight polyethylene can be obtained by direct sintering of polymer powder obtained by polymerization, compression molding, extrusion molding using a ram extruder for extrusion molding with intermittent compression, and dispersion in a solvent or the like. After extrusion molding, it is molded by a method such as a method of removing the solvent. However, these molding and processing methods have high technical difficulty and it is difficult to obtain moldings, and furthermore, local high viscosity sites due to entanglement of polymer chains and flow of polymer particles Since a weak point is generated due to the formation of a sparse portion at the time of compression due to lack of physical properties etc., the resulting molded product can not exhibit the mechanical strength that it should have originally, and thus the mechanical strength Was relatively low.

  And as a means to raise the mechanical strength at the time of setting it as a molded object, the ultra high molecular weight polyethylene with narrow molecular weight distribution which used catalysts, such as a metallocene catalyst, is proposed (for example, refer patent documents 1, 2).

Patent No. 4868853 (For example, see the claims.) Unexamined-Japanese-Patent No. 2006-36988 (For example, refer to a claim.)

  However, even with the ultrahigh molecular weight polyethylenes proposed in Patent Documents 1 and 2, although there is an improvement in the performance as a molded product, they have not yet been satisfactory in terms of strength, heat resistance and crystallinity.

  In addition, the higher the molecular weight, the harder it is for the entanglement of molecular chains to be broken, so that the effect expected from the increase in molecular weight can not be sufficiently expressed. There is a problem that the molecular weight is maximum at about 3,000,000, and even if the molecular weight is higher than that, the tensile strength at break decreases.

  Then, this invention is made in view of the said subject, and it is possible to supply the molded object which is excellent in intensity | strength, heat resistance, and abrasion resistance, and is a novel super high which has a high melting point and a specific melting behavior. It aims at provision of molecular weight polyethylene particles.

  As a result of intensive studies to solve the above problems, the present inventors have found that a novel ultrahigh molecular weight polyethylene copolymer having a high melting point and a specific melting behavior is a molded article having excellent strength, heat resistance and wear resistance. It has been found that the present invention can be provided.

  That is, the present invention has an intrinsic viscosity (η) of 15 dL / g or more and 60 dL / g or less and a molecular weight distribution (Mw / Mn) of more than 3 and less than 6 and ethylene-propylene copolymer or ethylene-butene-1 copolymer. The present invention relates to an ultrahigh molecular weight polyethylene copolymer characterized by being a polymer.

  Hereinafter, the present invention will be described in detail.

The ultrahigh molecular weight polyethylene particles of the present invention have at least (1) an intrinsic viscosity (η) of 15 dL / g to 60 dL / g, (2) a bulk density of 100 kg / m ^{3 to} 700 kg / m ³ , (3) differential Melting point (Tm ₁ ) of 1st scan when heated up to 230 ° C. (1st scan) at a heating rate of 0 ° C. to 10 ° C./min with a scanning calorimeter (DSC), and then left for 5 minutes, The temperature is lowered to -20 ° C at a temperature drop rate of 10 ° C / min and left for 5 minutes, and then the temperature is raised again from -20 ° C to 230 ° C at a heating rate of 10 ° C / min (2nd scan) The melting point (Tm ₂ ) is measured, and the difference between the Tm ₁ and the Tm ₂ (ΔTm = Tm ₁ −Tm ₂ ) satisfies all of the characteristics of 11 ° C. or more and 30 ° C. or less.

  The ultra high molecular weight polyethylene particles of the present invention are those in which ultra high molecular weight polyethylene has a particle shape, and the ultra high molecular weight polyethylene belongs to the category called polyethylene, for example, ethylene homopolymer; ethylene -Ethylene-alpha-olefin copolymers, such as a propylene copolymer, an ethylene 1-butene copolymer, an ethylene 1-hexene copolymer, an ethylene 1-octene copolymer, etc. can be mentioned.

  The ultrahigh molecular weight polyethylene particles of the present invention have (1) intrinsic viscosity (η) of 15 dL / g or more and 60 dL / g or less, and in particular, they have excellent moldability and mechanical properties when formed into a molded article. It is preferable that they are 15 dL / g or more and 50 dL / g or less. Here, when the intrinsic viscosity (η) is less than 15 dL / g, the resulting molded article is inferior in mechanical properties. On the other hand, when the intrinsic viscosity (η) exceeds 60 dL / g, since the fluidity when melted is low, the molding processability becomes very poor.

  The intrinsic viscosity (η) in the present invention is measured, for example, using a Ubbelohde viscometer at 135 ° C. in a solution having a polymer concentration of 0.0005 to 0.01% using orthodichlorobenzene as a solvent. It is possible.

The ultrahigh molecular weight polyethylene particles of the present invention have (2) bulk density of 130 kg / m ³ or more and 700 kg / m ³ or less, and more preferably 200 kg / m ³ or more and 600 kg / m ³ or less. Here, when the bulk density of the ultra-high molecular weight polyethylene particles is less than 130 kg / m ³ , the flowability of the particles is reduced, the filling rate in the storage container and the hopper is reduced, etc. It becomes easy to generate a task. On the other hand, when the bulk density exceeds 700 kg / m ³ , the central part of the particles remains unmelted in melting, solvent dissolution, etc. at the time of molding and processing, and the appearance of the molded body is lowered. It becomes easy to generate problems such as decline. The bulk density in the present invention can be measured, for example, by a method in accordance with JIS K 6760 (1995).

In addition, the ultrahigh molecular weight polyethylene particles of the present invention are (3) heated to 230 ° C. (1st scan) at a temperature rising rate of 0 ° C. to 10 ° C./min with a differential scanning calorimeter (DSC) Melting point (Tm ₁ ) of 1st scan, then, leave for 5 minutes, then lower temperature to -20 ° C at 10 ° C / min, and leave for 5 minutes, then again -20 ° C at 10 ° C / min. The melting point (Tm ₂ ) of the 2nd scan at the time of temperature rise from 2 to 230 ° C. (2nd scan) is measured, and the difference between Tm ₁ and Tm ₂ (ΔTm = Tm ₁ −Tm ₂ ) is 11 ° C. to 30 ° C. It is preferable that ΔTm is 11 ° C. or more and 15 ° C. or less because it is an ultrahigh molecular weight polyethylene particle which is excellent in the balance among heat resistance, mechanical strength and moldability. Here, when ΔTm is less than 11 ° C., the obtained ultrahigh molecular weight polyethylene particles become inferior in heat resistance, strength and the like. On the other hand, when ΔTm exceeds 30 ° C., dissolution of the resulting ultra-high molecular weight polyethylene particles when subjected to molding processing becomes difficult, and not only is the molding processability inferior, but the resulting molded product also has physical properties. It is inferior to

In addition, in general polyethylene, an ethylene homopolymer belonging to high density polyethylene is known as polyethylene having a high melting point. However, the melting point of the high density polyethylene is as low as about 130 to 135 ° C. On the other hand, the ultrahigh molecular weight polyethylene particles of the present invention have extremely high melting points (Tm) as compared to conventionally known polyethylene, for example, 140 for Tm ₁ if it is an ethylene homopolymer. It has a very high melting point above ° C. In the ultrahigh molecular weight polyethylene particles of the present invention, the molecular chains of polyethylene are highly crystallized, for example, by orientation, so Tm ₁ and Tm ₂ when measured by a differential scanning calorimeter (DSC). It is believed that the difference ΔTm is an extremely large difference of 11 ° C. or more and 30 ° C. or less.

In addition, although the reason for the ultrahigh molecular weight polyethylene particles in the present invention to have such extremely high melting point (Tm ₁ ) and ΔTm is unknown, the influence of heat history and the like at the time of manufacturing as ultrahigh molecular weight polyethylene particles I think that I have received.

  The ultra-high-molecular-weight polyethylene particles of the present invention can suppress discoloration (yellowing) or oxidative deterioration caused by titanium, have good color tone, and are excellent in weather resistance. The content is preferably low, and in particular, the content of (4) titanium is preferably 0.02 ppm or less or less than the detection limit. The content of titanium can be determined by measurement using a chemical titration method, a fluorescent X-ray analyzer, an ICP emission analyzer, or the like.

Moreover, since the ultrahigh molecular weight polyethylene particles of the present invention can provide a tougher molded body, (5) after heat compression at a press temperature of 190 ° C. and a press pressure of 20 MPa, the above (3) The tensile breaking strength (TS (MPa)) of a sheet formed by cooling at a mold temperature 10 ° C. to 30 ° C. lower than the measured melting point (Tm ₂ ) of the second scan satisfies the following relational expression (a) It is preferable to satisfy the following relational expression (c) because it is possible to provide a molded product which is further tough and which is excellent in mechanical strength and abrasion resistance.
_{TS ≧ 1.35 × Tm 2 -130 (} a)
1.35 × Tm ₂ −130 ≦ TS ≦ 2 × Tm ₂ −175 (c)
In addition, the tensile breaking strength of general polyethylene is as low as about 45 MPa even for the highest density polyethylene. In addition, the conventional ultrahigh molecular weight polyethylene was not able to fully utilize its high molecular weight, and the tensile strength at break was equivalent to that of general polyethylene and never exceeded 50 MPa. For this reason, there has been adopted a method of enhancing the strength by orienting by rolling forming at a high draw ratio or the like.

  However, the ultrahigh molecular weight polyethylene particles of the present invention have higher molecular weight even in the region of ultrahigh molecular weight polyethylene having an intrinsic viscosity (η) exceeding 15 dL / g because the polymer chains are appropriately intertwined. However, the tensile strength at break does not decrease, but rather tends to further improve. And since the ultrahigh molecular weight polyethylene particles of the present invention are superior in strength when formed into a molded product, the tensile breaking strength measured according to the above (5) if belonging to the area of high density polyethylene Is preferably 40 MPa or more, more preferably 50 MPa or more.

  The conditions for measuring the tensile strength at break in the present invention are not particularly limited. For example, test pieces such as strips of 0.1 to 5 mm in thickness and 1 to 50 mm in width, dumbbell type, etc., tensile rate of 1 mm / min to 500 mm / min The method of measuring at the speed of

Furthermore, the ultrahigh molecular weight polyethylene particles of the present invention have a relatively low content of low molecular weight components, which enables appropriate entanglement of polymer chains, and in particular, they are excellent in heat resistance. The breaking strength (MTS (MPa)) when melt-drawing the formed sheet at a temperature 20 ° C. higher than the melting point (Tm ₂ ) of the 2nd scan measured according to (3) above is preferably 2 MPa or more Further, it is preferable to have 3 MPa or more.

  At a temperature 20 ° C. higher than the melting point (Tm), a general polyethylene having a molecular weight of 500,000 or less has high fluidity, and the molded body is deformed by its own weight, and melt drawing can not be performed. Also, conventional ultra-high molecular weight polyethylene can be melt drawn even at a temperature 20 ° C. higher than the melting point (Tm), but strain hardening does not occur under the influence of the contained low molecular weight components, and the stress remains low It was broken at a strength of around 1 MPa, and was poor in heat resistance.

  And there is no restriction as a forming condition of the heating compression forming sheet used for melt drawing, for example, conditions of 100 to 250 ° C. of press temperature and 5 to 50 MPa of press pressure, among them, especially the heat compression described in the above (5) A molding method can be illustrated. In addition, as a melt drawing method, for example, a method of drawing a test piece such as a strip having a thickness of 0.1 to 5 mm and a width of 1 to 50 mm or a dumbbell shape at a tensile speed of 1 mm / min to 500 mm / min is exemplified. be able to.

Moreover, since the ultrahigh molecular weight polyethylene particles of the present invention are particularly excellent in heat resistance, (7) breaking strength (MTS (MPa)) and intrinsic viscosity (MTS (MPa)) measured by (6) above. It is preferable that η) satisfy the following relational expression (b), and it is preferable to satisfy the following relational expression (d) because the melt stretchability and the formability are particularly excellent.
MTS 0.1 0.11 x b (b)
0.11 × η ≦ MTS ≦ 0.32 × η (d)
The ultrahigh molecular weight polyethylene particles of the present invention are particularly excellent in fluidity as powder and excellent in moldability at the time of molding and processing, so that the (8) average particle diameter is preferably 1 to 1000 μm. When the average particle diameter is 1 μm or more, the occurrence of fouling in the polymerization process, the occurrence of flow failure in the hopper or the like in the forming process, etc. can be suppressed. When the average particle size is 1000 μm or less, melting of the ultrahigh molecular weight polyethylene particles during molding and dissolution in a solvent become easy, and the physical properties of the molded article obtained are excellent as well as excellent in moldability. In addition, regarding an average particle diameter, it can measure, for example by methods, such as a sieving test method using the standard sieve prescribed | regulated by JISZ8801.

  The ultrahigh molecular weight polyethylene particles of the present invention have good fusion properties between particles during molding and the resulting molded article is excellent in heat resistance, strength, etc. (9) Weight average molecular weight ((9) The molecular weight distribution (Mw / Mn) represented by the ratio of Mw) to the number average molecular weight (Mn) is preferably more than 3 and less than 6, and particularly preferably more than 3 and less than 5. The weight average molecular weight and number average molecular weight at that time can be measured, for example, by gel permeation chromatography (sometimes referred to as GPC).

  The ultrahigh molecular weight polyethylene particles of the present invention may optionally contain various known additives, for example, tetrakis (methylene (3,5-di-t-butyl-4-hydroxy) hydrocinnamate) methane. Heat resistant stabilizers such as distearyl thiodipropionate; bis (2,2 ′, 6,6′-tetramethyl-4-piperidine) sebacate, 2- (2-hydroxy-t-butyl-5-methylphenyl) Examples include weathering stabilizers such as -5-chlorobenzotriazole, and the like. Further, inorganic or organic dry color may be added as a coloring agent. In addition, stearic acid salts such as calcium stearate which are known as lubricants and hydrogen chloride absorbents can also be mentioned as suitable additives.

  As a method for producing the ultrahigh molecular weight polyethylene particles of the present invention, any method may be used as long as the production of the ultrahigh molecular weight polyethylene particles of the present invention is possible. For example, homopolymerization of ethylene using a catalyst for producing polyethylene The method of copolymerizing ethylene and other olefins can be mentioned, and as the α-olefin in that case, for example, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene etc. Can be mentioned. Further, as the polymerization method, for example, methods such as solution polymerization method, bulk polymerization method, gas phase polymerization method, slurry polymerization method and the like can be mentioned, and among them, production of ultra high molecular weight polyethylene particles whose particle shape is particularly well It is possible to efficiently and stably produce ultra high molecular weight polyethylene particles that can provide a molded product having high melting point, high crystallinity and excellent mechanical strength, heat resistance, and abrasion resistance. It is preferable to use a slurry polymerization method. The solvent used in the slurry polymerization method may be any commonly used organic solvent, and examples thereof include benzene, toluene, xylene, pentane, hexane, heptane and the like, and liquefied gas such as isobutane and propane. Olefins such as propylene, 1-butene, 1-octene, 1-hexene can also be used as a solvent.

  Moreover, as a polyethylene production catalyst used to produce the ultrahigh molecular weight polyethylene particles of the present invention, any catalyst can be used as long as it can produce the ultrahigh molecular weight polyethylene particles, for example, at least transition Mention may be made of metallocene compounds obtained from metal compounds (A), organically modified clays (B) modified with aliphatic salts and organic aluminum compounds (C).

  And, as the transition metal compound (A), for example, a transition metal compound having a (substituted) cyclopentadienyl group and a (substituted) fluorenyl group, a transition having a (substituted) cyclopentadienyl group and a (substituted) indenyl group Metal compounds, transition metal compounds having a (substituted) indenyl group and a (substituted) fluorenyl group, and the like can be mentioned, and as a transition metal in that case, for example, zirconium, hafnium etc. can be mentioned. A zirconium compound having a (substituted) cyclopentadienyl group and an amino group-substituted fluorenyl group, a (substituted) cyclopentadienyl group and an amino group substituted, since it becomes possible to efficiently produce ultrahigh molecular weight polyethylene particles of It is preferable that it is a hafnium compound which has a fluorenyl group.

  And, more specifically, for example, diphenylmethylene (1-indenyl) (9-fluorenyl) zirconium dichloride, diphenylmethylene (1-indenyl) (2, 7-di-t-butyl-9-fluorenyl) zirconium dichloride, diphenyl Methylene (4-phenyl-1-indenyl) (2,7-di-t-butyl-9-fluorenyl) zirconium dichloride, diphenylsilanediyl (cyclopentadienyl) (2- (dimethylamino) -9-fluorenyl) zirconium Dichloride, diphenylsilanediyl (cyclopentadienyl) (2- (diethylamino) -9-fluorenyl) zirconium dichloride, diphenylsilanediyl (cyclopentadienyl) (2- (dibenzylamino) -9-fluorenyl) zyl Niumdichloride, diphenylsilanediyl (cyclopentadienyl) (2,7-bis (dimethylamino) -9-fluorenyl) zirconium dichloride, diphenylsilanediyl (cyclopentadienyl) (2,7-bis (diethylamino) -9 -Fluorenyl) zirconium dichloride, diphenylsilanediyl (cyclopentadienyl) (2,7-bis (dibenzylamino) -9-fluorenyl) zirconium dichloride, diphenylsilanediyl (cyclopentadienyl) (4- (dimethylamino)) -9-fluorenyl) zirconium dichloride, diphenylsilanediyl (cyclopentadienyl) (4- (diethylamino) -9-fluorenyl) zirconium dichloride, diphenylsilanediyl (cyclopentadiyl) Nyl) (4- (dibenzylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2- (dimethylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (di) 2- (diethylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2- (dibenzylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2,7- Bis (dimethylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2,7-bis (diethylamino) -9-fluorenyl) zirconium dichloride, diphenyl Methylene (cyclopentadienyl) (2,7-bis (dibenzylamino) -9-fluorenyl) zirconium dichloride diphenylmethylene (cyclopentadienyl) (4- (dimethylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (Cyclopentadienyl) (4- (diethylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (4- (dibenzylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) Enyl) (2,7-bis (dimethylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2,7-bis (diethylamino) -9-fluorenyl) zyl Sodium dichloride, diphenylmethylene (cyclopentadienyl) (2,7-bis (diisopropylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2,7-bis (di-n-butyl-) Amino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2,7-bis (dibenzylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (3,6- Bis (dimethylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (3,6-bis (diethylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclope) Tadienyl) (3,6-bis (di-n-propyl-amino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2,5-bis (dimethylamino) -9-fluorenyl) zirconium dichloride Diphenylmethylene (cyclopentadienyl) (2,5-bis (diethylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2,5-bis (diisopropylamino) -9-fluorenyl) zirconium Zirconium compounds such as dichloride; Zirconium compounds in which their dichloro form is converted to dimethyl form, diethyl form, dihydro form, diphenyl form, dibenzyl form, and hafnium compounds in which the zirconium of these compounds is converted to hafnium An object etc. can be illustrated.

  Examples of the organically modified clay (B) modified with the aliphatic salt include, for example, N, N-dimethyl-behenylamine hydrochloride, N-methyl-N-ethyl-behenylamine hydrochloride, N-methyl-N-n- Propyl-behenylamine hydrochloride, N, N-dioleyl-methylamine hydrochloride, N, N-dimethyl-behenylamine hydrofluoride, N-methyl-N-ethyl-behenylamine hydrofluoride, N- Methyl-N-n-propyl-behenylamine hydrofluoride, N, N-dioleyl-methylamine hydrofluoride, N, N-dimethyl-behenylamine hydrobromide, N-methyl-N- Ethyl-behenylamine hydrobromide, N-methyl-Nn-propyl-behenylamine hydrobromide, N, N-dioleyl-methylamine hydrobromide, N, N-dimethyl-beth Nylamine hydroiodide, N-methyl-N-ethyl-behenylamine hydroiodide, N-methyl-Nn-propyl-behenylamine hydroiodide, N, N-dioleyl-methylamine iodination Hydrochloride, N, N-dimethyl-behenylamine sulfate, N-methyl-N-ethyl-behenylamine sulfate, N-methyl-N-n-propyl-behenylamine sulfate, N, N-dioleyl-methyl Aliphatic amine salts such as amine sulfates; P, P-dimethyl-behenylphosphine hydrochloride, P, P-diethyl-behenylphosphine hydrochloride, P, P-dipropyl-behenylphosphine hydrochloride, P, P-dimethyl-behenyl Phosphine hydrofluoride, P, P-diethyl-behenylphosphine hydrofluoride, P, P-dipropyl-behenylphosphine Hydrochloride, P, P-Dimethyl-behenylphosphine hydrobromide, P, P-diethyl-behenylphosphine hydrobromide, P, P-dipropyl-behenylphosphine hydrobromide, P, P- Dimethyl-behenylphosphine hydroiodide, P, P-diethyl-behenylphosphine hydroiodide, P, P-dipropyl-behenylphosphine hydroiodide, P, P-dimethyl-behenylphosphine sulfate, P And aliphatic phosphonium salts such as P-diethyl-behenylphosphine sulfate and P, P-dipropyl-behenylphosphine sulfate; and clays modified with aliphatic salts such as, for example.

The clay compound constituting the organically modified clay (B) may be any clay compound as long as it belongs to the category of clay compounds, and generally a tetrahedron in which a silica tetrahedron is continuous in two dimensions A number of layers called “silicate layers,” which are configured by combining a sheet and an octahedral sheet in which alumina octahedra, magnesia octahedra, etc. are continuous on two dimensions in a 1: 1 or 2: 1 manner, are formed. Some of the tetrahedral silica is Al, the alumina octahedral Al is Mg, and the magnesia octahedral Mg is homogeneously substituted by Li etc. The positive charge inside the layer is insufficient, and the entire layer is negatively charged. It is known that a cation such as Na ⁺ or Ca ²⁺ is present between the layers to compensate for this negative charge. And, as the clay compound, natural products or kaolinite as synthetic products, talc, smectite, vermiculite, mica, brittle mica, curd mica, and the like can be used, and it is possible to use these, among which it is possible to obtain Smectite is preferable in view of easiness of treatment and easiness of organic modification, and particularly hectorite or montmorillonite is more preferable among smectites.

  The organically modified clay (B) can be obtained by introducing the aliphatic salt between layers of the clay compound to form an ionic complex. When preparing the organically modified clay (B), it is preferable to carry out treatment by selecting the concentration of the clay compound of 0.1 to 30% by weight and the treatment temperature of 0 to 150 ° C. In addition, the aliphatic salt may be prepared as a solid and used by being dissolved in a solvent, or a solution of the aliphatic salt may be prepared by a chemical reaction in a solvent and used as it is. With respect to the reaction amount ratio of the clay compound to the aliphatic salt, it is preferable to use an aliphatic salt having an equivalent or more equivalent to the exchangeable cation of the clay compound. Examples of processing solvents 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 And halogenated hydrocarbons such as methylene chloride and chloroform; acetone; 1,4-dioxane; tetrahydrofuran; water and the like can be used. And preferably, an alcohol or water is used alone or as one component of a solvent.

  Further, the particle size of the organically modified clay (B) constituting the catalyst for producing polyethylene of the present invention is not particularly limited, and among them, the efficiency at the time of catalyst preparation and the efficiency at the time of producing polyethylene are excellent. Is preferred. There is no limitation on the method of controlling the particle size at that time, and large particles may be crushed to obtain an appropriate particle size, or small particles may be granulated to obtain an appropriate particle size, or crushing and granulation may be performed. You may combine them. The particle size may be adjusted to the clay before organic modification or to the organic modified clay after modification.

  As the organoaluminum compound (C), any compound can be used as long as it belongs to a category called organoaluminum compound, and examples thereof include alkylaluminums such as trimethylaluminum, triethylaluminum and triisobutylaluminum. Can.

  The transition metal compound (A) (hereinafter sometimes referred to as component (A)) constituting the catalyst for producing polyethylene, the organically modified clay (B) (hereinafter sometimes referred to as component (B)), and The proportion of the organoaluminum compound (C) (hereinafter sometimes referred to as component (C)) is not particularly limited as long as it can be used as a catalyst for producing polyethylene, and, among them, particularly, The molar ratio of component (A) to component (C) per metal atom is (A component): (C component) because it becomes a catalyst for producing polyethylene capable of efficiently producing ultrahigh molecular weight polyethylene particles. It is preferably in the range of 100: 1 to 1: 100000, and particularly preferably in the range of 1: 1 to 1: 10,000. Further, the weight ratio of the component (A) to the component (B) is preferably in the range of (A component) :( B component) = 10: 1 to 1: 10,000, particularly in the range of 3: 1 to 1: 1000. Is preferred.

  With regard to the method for preparing the polyethylene production catalyst, any method may be used if it is possible to prepare at least the component (A), the component (B) and the component (C) from which the catalyst for polyethylene production is obtained. For example, a method of mixing in a solvent inert to each of the components (A), (B) and (C) or using a monomer to be polymerized as a solvent can be mentioned. In addition, there is no restriction as to the order in which these components are reacted, and there are no restrictions on the temperature at which this treatment is carried out and the treatment time. Moreover, it is also possible to prepare a catalyst for producing polyethylene using two or more kinds of each of the component (A), the component (B) and the component (C).

  The polymerization conditions such as polymerization temperature, polymerization time, polymerization pressure, monomer concentration, etc. when producing the ultrahigh molecular weight polyethylene particles of the present invention can be arbitrarily selected. Among them, polymerization temperature 0 to 100 ° C., polymerization time 10 The polymerization pressure is preferably in the range of normal pressure to 100 MPa for a period of 2 to 20 hours. Moreover, it is also possible to control molecular weight using hydrogen etc. at the time of polymerization. The polymerization can be carried out either batchwise, semicontinuously or continuously, and it is also possible to carry out the polymerization in two or more stages by changing the polymerization conditions. The polyethylene particles obtained after completion of the polymerization can be separated and recovered from the polymerization solvent by a conventionally known method and dried.

  The molded article comprising the ultrahigh molecular weight polyethylene particles of the present invention can be obtained by a known molding method. Specifically, methods such as extrusion molding such as ram extrusion, compression molding, powder coating, sheet molding, rolling molding, and stretching molding in a state of being dissolved or mixed in various solvents can be exemplified. The molded article of the present invention has high strength even after molding, and can be used as lining materials, line parts for food industry, machine parts, artificial joint parts, sports goods, microporous membranes, nets, ropes, gloves and the like.

  The ultrahigh molecular weight polyethylene particles of the present invention have a high melting point and exhibit high crystallinity, so that the molded product obtained therefrom is excellent in mechanical strength, heat resistance and abrasion resistance, and is excellent in various industrial equipment and the like. It has excellent characteristics as a base material and the like.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited by these examples.

  In addition, unless otherwise noted, the reagents used were commercially available products or those synthesized according to known methods.

  A jet mill (manufactured by Seishin Enterprise Co., Ltd. (trade name) CO-JET SYSTEM α MARK III) is used for pulverizing the organically modified clay, and the particle size after pulverization is a microtrack particle size distribution measuring apparatus (manufactured by Nikkiso Co., Ltd. Ethanol) was measured as a dispersant using MT 3000).

  Preparation of catalyst for polyethylene production, production of polyethylene and solvent purification were all performed under an inert gas atmosphere. The hexane solution (20 wt%) of triisobutylaluminum used Tosoh Fine Chem Co., Ltd. product.

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

~ Measurement of intrinsic viscosity ~
Measurement was carried out using an Ubbelohde viscometer using ODCB (orthodichlorobenzene) as a solvent at a temperature of 135 ° C. and an ultrahigh molecular weight polyethylene concentration of 0.005 wt%.

~ Measurement of weight average molecular weight, number average molecular weight ~
The weight average molecular weight (Mw), the number average molecular weight (Mn), and the ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) were measured by GPC. GPC apparatus (Senshu Scientific Co., Ltd. (trade name) SSC-7110) and column (Tosoh Corp., (trade name) TSKguard column H _HR (S) HT × 1, manufactured by Tosoh Corp., (trade name) The column temperature was set to 210 ° C. using TSKgel GMH _HR -H (S) HT × 2), and measurement was performed using 1-chloronaphthalene as an eluent. The measurement sample was prepared at a concentration of 0.5 mg / ml, and 0.2 ml was injected and measured. The molecular weight calibration curve was calibrated using polystyrene samples of known molecular weight. The molecular weight was converted to the molecular weight of polyethylene using a Q factor to obtain a value.

~ Measurement of bulk density ~
It measured by the method based on JIS K 6760 (1995).

~ Measurement of Tm ₁ and Tm ₂ ~
Using a differential scanning calorimeter (DSC) (manufactured by SII Nano Technology Co., Ltd. (trade name) DSC 6220), the temperature is raised to 230 ° C. at a heating rate of 0 ° C. to 10 ° C./min (1st scan) The crystal melting peak (Tm ₁ ) of the 1st scan was measured. Then, after standing for 5 minutes, the temperature is lowered to -20 ° C at a temperature lowering rate of 10 ° C / min, and after standing for 5 minutes, the temperature is raised again from -20 ° C to 230 ° C at a heating rate of 10 ° C / min (2nd scan 2.) The crystal melting peak (Tm ₂ ) of the 2nd scan was measured. The sample amount of ultrahigh molecular weight polyethylene at that time was 6 mg.

~ Measurement of titanium content ~
Using a solution prepared by ashing and alkali-melting ultrahigh molecular weight polyethylene particles, using an ICP emission analyzer (manufactured by PerkinElmer Co., Ltd., (trade name) Optima 3000 XL), titanium-containing titanium in ultrahigh molecular weight polyethylene particles The amount was measured.

Measurement of tensile breaking strength
The ultrahigh molecular weight polyethylene particles were sandwiched between polyethylene terephthalate films, preheated at 190 ° C. for 5 minutes, and then heated and compressed at 190 ° C. under a pressure of 20 MPa. Then, it was cooled for 10 minutes at a mold temperature of 110 ° C. to obtain a 0.3 mm thick pressed sheet.

  A sample (5 mm in width of the measurement part) cut out from the sheet into a dumbbell shape is allowed to stand at 23 ° C. for 48 hours, and then a tensile tester (trade name: Tensilon RTG- (manufactured by A & D Co., Ltd.) In 1210), a tensile test was performed at a measurement temperature of 23 ° C., an initial length of a test piece of 20 mm, and a tensile speed of 20 mm / min to determine a tensile breaking strength.

~ Measurement of breaking stress at melt drawing ~
A press sheet was obtained by the method described in the measurement of the tensile breaking strength.

A sample (10 mm in width of the measurement part) cut into a dumbbell shape from this sheet is allowed to stand at 23 ° C. for 48 hours, and then a tensile tester (trade name: Tensilon UMT 2. manufactured by A & D Co., Ltd.). At 5 T), a tensile test is performed at a temperature 20 ° C. higher than the crystalline melting peak (Tm ₂ ) of the 2nd scan of the differential scanning calorimeter (DSC) at an initial length of 10 mm of the test piece and a tensile speed of 20 mm / min. The breaking stress at the time of melt drawing was determined. When strain hardening occurs and stress increases with stretching, the maximum value is taken as the breaking stress, and when strain hardening does not occur and stress does not increase after stretching, the stress in the flat area after yielding is taken as breaking stress. did.

~ Measurement of average particle size ~
Obtained when 100 g of ultrahigh molecular weight polyethylene particles are classified using nine types of sieves (mesh openings: 710 μm, 500 μm, 425 μm, 300 μm, 212 μm, 150 μm, 106 μm, 75 μm, 53 μm) specified by JIS Z8801. The average particle size was determined by measuring the particle size at which the weight becomes 50% in an integral curve obtained by integrating the weight of particles remaining on each sieve from the side with a large opening.

-Evaluation of abrasion resistance-
200 g of ultrahigh molecular weight polyethylene particles were put into a mold and press molded for 20 minutes at a mold temperature of 190 ° C. and a surface pressure of 30 MPa to obtain a plate-shaped molded article having 150 mm in length and 10 mm in thickness.

  The plate-like molded product is cut using a planer to prepare a round bar with a diameter of 5 mm and a height of 8 mm as a test sample, and a friction and wear tester (Orientec Co., Ltd., type EFM-III-EN) The amount of wear was measured under the conditions of a partner material SS400 using a speed of 2.0 m / sec, a load of 25 MPa, and a time of 360 minutes in accordance with JIS K7218. The smaller the amount of wear, the better the wear resistance.

Example 1
(1) Preparation of organically modified clay In a 1 liter flask, 300 ml of industrial alcohol (manufactured by Nippon Alcohol Sales Co., Ltd. (trade name) Echinen F-3) and 300 ml of distilled water are added, 15.0 g of concentrated hydrochloric acid and dioleyl methylamine 64.2 g (120 mmol) of (Lion Co., Ltd. (trade name) Armin M20) was added, and the mixture was heated to 45 ° C. to disperse 100 g of synthetic hectorite (Rockwood Additives, (trade name) Laponite RDS) Thereafter, the temperature was raised to 60 ° C., and the mixture was stirred for 1 hour while maintaining the temperature. The slurry was separated by filtration, washed twice with 600 ml of water at 60 ° C., and dried in an oven at 85 ° C. for 12 hours to obtain 160 g of an organically modified clay. The organically modified clay was jet-milled to a median diameter of 7 μm.

(2) Preparation of suspension of catalyst for polyethylene production After nitrogen substitution in a 300 ml flask equipped with a thermometer and a reflux tube, 25.0 g of the organically modified clay obtained in (1) and 108 ml of hexane are added, and then Add 0.795 g of diphenylmethylene (4-phenyl-1-indenyl) (2,7-di-t-butyl-9-fluorenyl) zirconium dichloride and 142 ml of 20% triisobutylaluminum and stir at 60 ° C. for 3 hours did. After cooling to 45 ° C., the supernatant was drained and washed twice with 200 ml of hexane, and then 200 ml of hexane was added to obtain a suspension of a catalyst for polyethylene production (solid weight ratio: 11.7 wt%).

(3) Production of ultra-high molecular weight polyethylene particles In a 2-liter autoclave, 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum, and 356 mg of the suspension of the catalyst for producing polyethylene obtained in (2) Solid content (equivalent to 41.7 mg) was added, and after the temperature was raised to 40 ° C., ethylene was continuously supplied so that the partial pressure was 1.6 MPa, and slurry polymerization of ethylene was performed. After 180 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 37.1 g of ultrahigh molecular weight ethylene homopolymer particles (activity: 890 g / g catalyst). Physical properties of the obtained ultrahigh molecular weight ethylene homopolymer particles are shown in Table 1.

Example 2
The preparation of (1) preparation of organically modified clay and (2) preparation of a suspension of a catalyst for producing polyethylene were carried out in the same manner as in Example 1.

(3) Production of ultra-high molecular weight polyethylene particles In a 2-liter autoclave, 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum, and 326 mg of the suspension of the catalyst for producing polyethylene obtained in (2) Solid content (equivalent to 38.2 mg) was added, and after 30 ° C., 5 g of propylene was added, ethylene was continuously supplied so that the partial pressure was 1.6 MPa, and slurry polymerization was performed. After 180 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 35.1 g of ultrahigh molecular weight ethylene-propylene copolymer particles (activity: 920 g / g catalyst). Physical properties of the obtained ultrahigh molecular weight ethylene-propylene copolymer particles are shown in Table 1.

Example 3
(1) Preparation of Organically Modified Clay The same procedure as in Example 1 was carried out.

(2) Preparation of suspension of catalyst for polyethylene production After nitrogen substitution in a 300 ml flask equipped with a thermometer and a reflux tube, 25.0 g of the organically modified clay obtained in (1) and 108 ml of hexane are added, and then 0.600 g of diphenylmethylene (cyclopentadienyl) (2- (dimethylamino) -9-fluorenyl) zirconium dichloride and 142 ml of 20% triisobutylaluminum were added and stirred at 60 ° C. for 3 hours. After cooling to 45 ° C., the supernatant was drained and washed twice with 200 ml of hexane, and then 200 ml of hexane was added to obtain a suspension of a catalyst for polyethylene production (solid weight ratio: 11.5 wt%).

(3) Production of ultra-high molecular weight polyethylene particles In a 2-liter autoclave, 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum, and 236 mg of the suspension of the catalyst for producing polyethylene obtained in (2) Solid content (equivalent to 27.1 mg) was added, and the temperature was raised to 50 ° C., ethylene was continuously supplied so that the partial pressure was 1.1 MPa, and slurry polymerization of ethylene was performed. After 180 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 152 g of ultrahigh molecular weight ethylene homopolymer particles (activity: 5600 g / g catalyst). Physical properties of the obtained ultrahigh molecular weight ethylene homopolymer particles are shown in Table 1.

Example 4
The preparation of (1) preparation of organically modified clay and (2) preparation of a suspension of a catalyst for producing polyethylene were carried out in the same manner as in Example 3.

(3) Production of ultrahigh molecular weight polyethylene particles In a 2-liter autoclave, 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum, 1.0 ml of 20% triisobutylaluminum, and the suspension of the catalyst for producing polyethylene obtained in (2) were treated as 89. 9 mg (solid content: 10.3 mg equivalent) was added, and after raising the temperature to 50 ° C., 2 g of 1-butene was added, and ethylene was continuously supplied to achieve partial pressure of 1.1 MPa to carry out slurry polymerization. After 180 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 64.1 g of ultrahigh molecular weight ethylene-butene-1 copolymer particles (activity: 6200 g / g catalyst). Physical properties of the obtained ultrahigh molecular weight ethylene-butene-1 copolymer particles are shown in Table 1.

Example 5
The preparation of (1) preparation of organically modified clay and (2) preparation of a suspension of a catalyst for producing polyethylene were carried out in the same manner as in Example 3.

(3) Production of ultrahigh molecular weight polyethylene particles In a 2-liter autoclave, 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum, 1.0 ml of 20% triisobutylaluminum, and the suspension of the catalyst for producing polyethylene obtained in (2) After 4 mg (equivalent to 40.5 mg of solid content) was added and the temperature was raised to 30 ° C., 20 g of propylene was added, and ethylene was continuously supplied so that the partial pressure was 1.6 MPa to carry out slurry polymerization. After 180 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 85.1 g of ultrahigh molecular weight ethylene-propylene copolymer particles (activity: 2100 g / g catalyst). Physical properties of the obtained ultrahigh molecular weight ethylene-propylene copolymer particles are shown in Table 1.

Example 6
(1) Preparation of organically modified clay In a 1-liter flask, 300 ml of industrial alcohol (manufactured by Nippon Alcohol Sales Co., (trade name) Echinen F-3) and 300 ml of distilled water are placed, 15.0 g of concentrated hydrochloric acid and dimethyl behenylamine ( 42.4 g (120 mmol) of Armin DM22D (trade name) made by Lion Corporation is added, and the mixture is heated to 45 ° C. to disperse 100 g of synthetic hectorite (Rockwood Additives, trade name: Laponite RDS) The mixture was heated to 60 ° C. and stirred for 1 hour while maintaining the temperature. The slurry was separated by filtration, washed twice with 600 ml of water at 60 ° C., and dried in an oven at 85 ° C. for 12 hours to obtain 125 g of an organically modified clay. The organically modified clay was jet-milled to a median diameter of 7 μm.

(2) Preparation of suspension of catalyst for polyethylene production After nitrogen substitution in a 300 ml flask equipped with a thermometer and a reflux tube, 25.0 g of the organically modified clay obtained in (1) and 108 ml of hexane are added, and then 0.715 g of diphenylmethylene (cyclopentadienyl) (2- (diethylamino) -9-fluorenyl) hafnium dichloride and 142 ml of 20% triisobutylaluminum were added and stirred at 60 ° C. for 3 hours. After cooling to 45 ° C., the supernatant was drained and washed twice with 200 ml of hexane, and then 200 ml of hexane was added to obtain a suspension of a catalyst for polyethylene production (solid weight ratio: 12.9 wt%).

(3) Production of ultra-high molecular weight polyethylene particles In a 2-liter autoclave, 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum, 1.0 ml of 20% triisobutylaluminum, and the suspension of the catalyst for producing polyethylene obtained in (2). After 7 mg (solid content: 14.0 mg equivalent) was added, and the temperature was raised to 60 ° C., ethylene was continuously supplied so that the partial pressure was 1.3 MPa, and slurry polymerization of ethylene was performed. After 180 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 115 g of ultrahigh molecular weight ethylene homopolymer particles (activity: 8200 g / g catalyst). Physical properties of the obtained ultrahigh molecular weight ethylene homopolymer particles are shown in Table 1.

Example 7
The preparation of (1) preparation of organically modified clay and (2) preparation of a suspension of a catalyst for producing polyethylene were carried out in the same manner as in Example 6.

(3) Production of ultrahigh molecular weight polyethylene particles In a 2-liter autoclave, 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum, 1.0 ml of 20% triisobutylaluminum, and the suspension of the catalyst for producing polyethylene obtained in (2). After adding 4 mg (corresponding to 11.0 mg of solid content) and raising the temperature to 60 ° C., 5 g of propylene was added, ethylene was continuously supplied so that the partial pressure was 1.3 MPa, and slurry polymerization of ethylene was performed. After 180 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 97 g of ultrahigh molecular weight ethylene-propylene copolymer particles (activity: 8800 g / g catalyst). Physical properties of the obtained ultrahigh molecular weight ethylene-propylene copolymer particles are shown in Table 1.

Example 8
The preparation of (1) preparation of organically modified clay and (2) preparation of a suspension of a catalyst for producing polyethylene were carried out in the same manner as in Example 6.

(3) Production of ultra-high molecular weight polyethylene particles In a 2-liter autoclave, 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum, 1.0 ml of 20% triisobutylaluminum, and the suspension of the catalyst for producing polyethylene obtained in (2) After adding 7 mg (solid content 11.3 mg equivalent) and raising the temperature to 60 ° C, supply hydrogen / ethylene mixed gas containing 40 ppm of hydrogen so that the partial pressure is 1.2 Ma, and then change the partial pressure to 1.3 MPa Ethylene was continuously supplied to perform slurry polymerization of ethylene. After 180 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 86 g of ultrahigh molecular weight ethylene homopolymer particles (activity: 7600 g / g catalyst). Physical properties of the obtained ultrahigh molecular weight ethylene homopolymer particles are shown in Table 2.

Example 9
(1) Preparation of Organically Modified Clay The same procedure as in Example 6 was carried out.

(2) Preparation of suspension of catalyst for polyethylene production After nitrogen substitution in a 300 ml flask equipped with a thermometer and a reflux tube, 25.0 g of the organically modified clay obtained in (1) and 108 ml of hexane are added, and then 0.786 g of diphenylmethylene (cyclopentadienyl) (2,7-bis (diethylamino) -9-fluorenyl) hafnium dichloride and 142 ml of 20% triisobutylaluminum were added and stirred at 60 ° C. for 3 hours. After cooling to 45 ° C., the supernatant was drained and washed twice with 200 ml of hexane, and then 200 ml of hexane was added to obtain a suspension of a catalyst for polyethylene production (solid weight ratio: 11.6 wt%).

(3) Production of ultra-high molecular weight polyethylene particles In a 2-liter autoclave, 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum, 1.0 ml of 20% triisobutylaluminum, and the suspension of the catalyst for producing polyethylene obtained in (2), 69. After adding 4 mg (equivalent to 8.1 mg of solid content) and adjusting to 60 ° C., supply to 1.3 MPa, and then continuously supply ethylene so that the partial pressure is 1.3 MPa, and a slurry of ethylene The polymerization was carried out. After 180 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 87 g of ultrahigh molecular weight ethylene homopolymer particles (activity: 10,800 g / g catalyst). Physical properties of the obtained ultrahigh molecular weight ethylene homopolymer particles are shown in Table 2.

Example 10
(1) Preparation of organically modified clay and (2) preparation of a suspension of a catalyst for producing polyethylene were carried out in the same manner as in Example 9.

(3) Production of ultra high molecular weight polyethylene particles In a 2-liter autoclave, 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum, 1.0 ml of 20% triisobutylaluminum, and the suspension of the catalyst for producing polyethylene obtained in (2) After 7 mg (solid content: equivalent to 9.1 mg) was added, the temperature was raised to 60 ° C., 20 g of propylene was added, ethylene was continuously supplied so that the partial pressure was 1.3 MPa, and slurry polymerization of ethylene was performed. After 180 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 105 g of ultrahigh molecular weight ethylene-propylene copolymer particles (activity: 11500 g / g catalyst). Physical properties of the obtained ultrahigh molecular weight ethylene-propylene copolymer particles are shown in Table 2.

Example 11
(1) Preparation of organically modified clay In a 1 liter flask, 300 ml of industrial alcohol (manufactured by Nippon Alcohol Sales Co., Ltd. (trade name) Echinen F-3) and 300 ml of distilled water are added, 15.0 g of concentrated hydrochloric acid and dioleyl methylamine 64.2 g (120 mmol) of (Lion Co., Ltd. (trade name) Armin M20) was added, and the mixture was heated to 45 ° C. to disperse 100 g of synthetic hectorite (Rockwood Additives, (trade name) Laponite RDS) Thereafter, the temperature was raised to 60 ° C., and the mixture was stirred for 1 hour while maintaining the temperature. The slurry was separated by filtration, washed twice with 600 ml of water at 60 ° C., and dried in an oven at 85 ° C. for 12 hours to obtain 160 g of an organically modified clay. The organically modified clay was jet-milled to a median diameter of 15 μm.

(2) Preparation of suspension of catalyst for polyethylene production After nitrogen substitution in a 300 ml flask equipped with a thermometer and a reflux tube, 25.0 g of the organically modified clay obtained in (1) and 108 ml of hexane are added, and then 0.700 g of diphenylmethylene (cyclopentadienyl) (2,7-bis (diethylamino) -9-fluorenyl) zirconium dichloride and 142 ml of 20% triisobutylaluminum were added and stirred at 60 ° C. for 3 hours. After cooling to 45 ° C., the supernatant was drained and washed twice with 200 ml of hexane, and then 200 ml of hexane was added to obtain a suspension of a catalyst for polyethylene production (solid weight ratio: 13.2 wt%).

(3) Production of ultrahigh molecular weight polyethylene particles In a 2-liter autoclave, 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum, and a suspension of the catalyst for producing polyethylene obtained in (2) were subjected to 306. After adding 4 mg (equivalent to 40.4 mg of solid content) and bringing it to 50 ° C, it is fed to 1.1 MPa, then ethylene is fed continuously so that the partial pressure is 1.1 MPa, and a slurry of ethylene The polymerization was carried out. After 180 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 182 g of ultrahigh molecular weight ethylene homopolymer particles (activity: 4500 g / g catalyst). Physical properties of the obtained ultrahigh molecular weight ethylene homopolymer particles are shown in Table 2.

Example 12
(1) Preparation of Organically Modified Clay The same procedure as in Example 6 was carried out.

(2) Preparation of suspension of catalyst for polyethylene production After nitrogen substitution in a 300 ml flask equipped with a thermometer and a reflux tube, 25.0 g of the organically modified clay obtained in (1) and 108 ml of hexane are added, and then 0.752 g of diphenylmethylene (cyclopentadienyl) (2- (dibenzylamino) -9-fluorenyl) zirconium dichloride and 142 ml of 20% triisobutylaluminum were added and stirred at 60 ° C. for 180 minutes. After cooling to 45 ° C., the supernatant was drained and washed twice with 200 ml of hexane, and then 200 ml of hexane was added to obtain a catalyst suspension (solid weight fraction: 12.2 wt%).

(3) Production of ultra-high molecular weight polyethylene particles In a 2-liter autoclave, 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum, 1.0 ml of 20% triisobutylaluminum, and the suspension of the catalyst for producing polyethylene obtained in (2) 301. After 5 mg (corresponding to 36.8 mg of solid content) was added, the temperature was raised to 60 ° C., ethylene was continuously supplied so that the partial pressure was 1.3 MPa, and slurry polymerization of ethylene was performed. After 90 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 103 g of ultrahigh molecular weight polyethylene particles (activity: 2800 g / g catalyst). Physical properties of the obtained ultrahigh molecular weight polyethylene particles are shown in Table 2.

Example 13
The preparation of (1) preparation of organically modified clay and (2) preparation of a suspension of a catalyst for producing polyethylene were carried out in the same manner as in Example 8.

(3) Production of ultra high molecular weight polyethylene particles In a 2 liter autoclave, 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum, 1.0 ml of 20% triisobutylaluminum, and the suspension of the catalyst for producing polyethylene obtained in (2) are obtained. After adding 6 mg (equivalent to 43.8 mg of solid content) to 60 ° C., supply a hydrogen / ethylene mixed gas containing 20 ppm of hydrogen so that the partial pressure is 1.2 MPa, and then the partial pressure becomes 1.3 MPa Thus, ethylene was continuously supplied to carry out slurry polymerization of ethylene. After 180 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 105 g of ultrahigh molecular weight polyethylene particles (activity: 2400 g / g catalyst). Physical properties of the obtained ultrahigh molecular weight polyethylene particles are shown in Table 2.

Comparative Example 1
(1) Preparation of Organically Modified Clay The procedure of Example 1 was repeated.

(2) Preparation of catalyst suspension After replacing the 300 ml flask equipped with a thermometer and a reflux condenser with nitrogen, 25.0 g of the organically modified clay obtained in (1) and 108 ml of hexane are added, and then bis (cyclopenta 0.292 g of dienyl) zirconium dichloride and 142 ml of 20% triisobutylaluminum were added and stirred at 60 ° C. for 3 hours. After cooling to 45 ° C., the supernatant was drained and washed twice with 200 ml of hexane, and then 200 ml of hexane was added to obtain a catalyst suspension (solid weight fraction: 11.8 wt%).

(3) Production of polyethylene particles 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum in a 2 liter autoclave, 1.095% of the catalyst suspension obtained in (2) 593.2 mg (solid content 70.0 mg) Correspondingly, ethylene was supplied continuously so that the partial pressure was 1.6 MPa after the temperature was raised to 30 ° C. After 90 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 105 g of ethylene homopolymer particles (activity: 1500 g / g of catalyst). Physical properties of the obtained ethylene homopolymer particles are shown in Table 3.

  The obtained ethylene homopolymer particles have a low intrinsic viscosity, almost no melting point difference (ΔTm) between the 1st scan and the 2nd scan (ΔTm = 0.7 ° C.), and are inferior in tensile strength and abrasion resistance. The In addition, although melt drawing was attempted, the sample was broken before drawing.

Comparative example 2
(1) Preparation of Organically Modified Clay The procedure of Example 1 was repeated.

(2) Preparation of catalyst suspension A 300 ml flask equipped with a thermometer and a reflux condenser was purged with nitrogen and then 25.0 g of the organically modified clay obtained in (1) and 108 ml of hexane were added, and then diphenylmethylene (cyclo 0.669 g of pentadienyl) (2,7-di-t-butyl-9-fluorenyl) zirconium dichloride and 142 ml of 20% triisobutylaluminum were added and stirred at 60 ° C. for 3 hours. After cooling to 45 ° C., the supernatant was drained and washed twice with 200 ml of hexane, and then 200 ml of hexane was added to obtain a catalyst suspension (solid weight fraction: 12.3 wt%).

(3) Production of polyethylene particles 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum in a 2 liter autoclave, and 170.0 mg of the catalyst suspension obtained in (2) (solid content 20.9 mg Correspondingly, ethylene was supplied continuously so that the partial pressure was 1.6 MPa after the temperature was raised to 30 ° C. After 90 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 115 g of ethylene homopolymer particles (activity: 5500 g / g catalyst). Physical properties of the obtained ethylene homopolymer particles are shown in Table 3.

The obtained ethylene homopolymer particles had a low intrinsic viscosity and a low Tm _{1 and} therefore were inferior in tensile strength at break and wear resistance. In addition, although melt drawing was attempted, the sample was broken before drawing.

Comparative example 3
(1) Preparation of solid catalyst component In a 1 liter glass flask equipped with a thermometer and a reflux condenser, 50 g (2.1 mol) of metallic magnesium powder and 210 g (0.62 mol) of titanium tetrabutoxide are added. Add 320 g (4.3 mol) of n-butanol in which 5 g was dissolved over 2 hours at 90 ° C., and stir at 140 ° C. for 2 hours under a nitrogen seal while excluding generated hydrogen gas to make a uniform solution . Then, 2100 ml of hexane was added.

  90 g of this component (corresponding to 0.095 mol with magnesium) was placed in a separately prepared 500 ml glass flask and diluted with 59 ml of hexane. At 45 ° C., 106 ml of a hexane solution containing 0.29 mol of isobutylaluminum dichloride was added dropwise over 2 hours, and the mixture was further stirred at 70 ° C. for 1 hour to obtain a solid catalyst component. The remaining unreacted materials and byproducts were removed by decantation using hexane, and the composition was analyzed to find that the titanium content was 8.6 wt%.

(2) Production of polyethylene particles 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum, and 4.2 mg of the solid catalyst component obtained in (1) were added to a 2-liter autoclave, and the temperature was raised to 80 ° C. After that, ethylene was continuously supplied to a partial pressure of 0.6 MPa. After 90 minutes, pressure was released, and the slurry was separated by filtration and dried to obtain 180 g of ethylene homopolymer particles (activity: 43000 g / g catalyst). Physical properties of the obtained ethylene homopolymer particles are shown in Table 3.

  The obtained ethylene homopolymer particles had a small melting point difference (ΔTm) between the 1st scan and the 2nd scan, and were inferior in tensile strength at break, strength at break during melt drawing, and abrasion resistance. Moreover, when it was set as a molded object, yellowing was seen and it had a subject also in moldability and quality.

Comparative example 4
The physical properties of commercially available polyethylene (trade name: Hi-Zex Million grade 240M, manufactured by Mitsui Chemicals, Inc.) were measured in the same manner as in the examples. The results are shown in Table 3.

  The melting point difference (ΔTm) between the 1st scan and the 2nd scan was small, and the tensile breaking strength, the breaking strength at the time of melt drawing, and the abrasion resistance were inferior. Moreover, when it was set as a molded object, yellowing was seen and it had a subject also in moldability and quality.

  The ultrahigh molecular weight polyethylene particles of the present invention have a high melting point and exhibit high crystallinity, which makes it possible to provide a molded article excellent in mechanical strength, heat resistance and abrasion resistance, and can be used industrially Sex is extremely high.

Claims (2)

The intrinsic viscosity (eta) is 15 dL / g or more 60dL / g or less, the molecular weight distribution (Mw / Mn) is less than greater than 3 6, the titanium content is less than or measuring the detection limit of less than 0.02 ppm, the following conditions (a Ethylene-propylene copolymer or ethylene-butene-1 having a stress at break of 2 MPa or more when melt-stretched at a temperature 20 ° C. higher than Tm ₂ measured under the following condition (b) : Ultrahigh molecular weight polyethylene copolymer characterized in that it is a copolymer.
(A) The ultrahigh molecular weight polyethylene copolymer is sandwiched between polyethylene terephthalate films, preheated for 5 minutes at 190 ° C., heated and compressed under the conditions of 190 ° C. and a pressure of 20 MPa, and then mold temperature 110 ° C. for 10 minutes The sheet is cooled to obtain a 0.3 mm thick press sheet, and a dumbbell-shaped test piece having a width of 10 mm is cut out from the press sheet.
(B) Melting point (Tm ₁ ) of the 1st scan when the temperature is raised to 230 ° C. (1st scan) at a temperature rise rate of 0 ° C. to 10 ° C./min with a differential scanning calorimeter (DSC ), then 5 After standing for 10 minutes, the temperature is lowered to -20 ° C at a rate of 10 ° C / min, and after standing for 5 minutes, the temperature is raised again from -20 ° C to 230 ° C at a temperature rise rate of 10 ° C / min (2nd scan) Measure the melting point (Tm ₂ ) of the 2nd scan of . 2. The ultrahigh molecular weight polyethylene copolymer according to claim 1, wherein the molecular weight distribution is greater than 3 and less than 5.