JP6357819B2 - Ultra high molecular weight polyethylene cutting - Google Patents

Description

  The present invention relates to a cut molded body formed by molding ultra-high molecular weight polyethylene particles having a high melting point and high crystallinity, and more specifically, because of excellent chemical resistance and wear resistance, The present invention relates to an ultra-high molecular weight polyethylene cutting molded body expected to be applied to rotating parts such as rollers and gears, medical parts such as artificial joint parts, deformed rails, pipes, balls, and bearings.

  The ultra high molecular weight ethylene polymer has an extremely high molecular weight corresponding to a viscosity average molecular weight (Mv) of 1 million or more, so that it has impact resistance, self-lubricity, abrasion resistance, weather resistance, chemical resistance It has excellent physical properties and dimensional stability, and has high physical properties comparable to engineering plastics. For this reason, application to applications such as lining materials, food industry line parts, machine parts, artificial joints, sporting goods, and microporous membranes has been attempted by various molding methods.

  However, ultra-high molecular weight ethylene polymer has extremely low fluidity when melted due to its high molecular weight, and it can be molded by kneading extrusion like ordinary polyethylene having a molecular weight in the range of tens of thousands to about 500,000. Have difficulty. Therefore, ultrahigh molecular weight polyethylene is a method of directly sintering polymer powder obtained by polymerization, a method of compression molding, a molding method by a ram extruder that extrudes while intermittently compressing, a state where it is dispersed in a solvent, etc. After extrusion molding, a method such as a method of removing the solvent is performed. Furthermore, a method of cutting a massive base material obtained by these methods is also known.

  Of these, ultra-high molecular weight polyethylene cuttings are made of ultra-high molecular weight polyethylene, such as low friction coefficient, wear resistance, chemical resistance, and rigidity. , Etc. However, the ultra-high molecular weight polyethylene produced by a Ziegler catalyst that is currently commercially available has a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (molecular weight distribution) larger than 4, and the molecular weight distribution is wide. The abrasion resistance and chemical resistance of the molded product cannot be said to be sufficiently improved as compared with normal molecular weight polyethylene, and cannot be said to exhibit the expected performance.

  On the other hand, an ultrahigh molecular weight ethylene polymer having a narrow molecular weight distribution produced by using a metallocene catalyst or a post metallocene catalyst has also been proposed (see, for example, Patent Documents 1 and 2).

Japanese Patent No. 4868853 (see, for example, claims) Japanese Patent Laying-Open No. 2006-36988 (for example, refer to the claims)

  However, when a cut molded body is manufactured using the ultrahigh molecular weight polyethylene proposed in Patent Documents 1 and 2, the performance as a molded product is improved, but the performance is not sufficiently satisfactory.

  In addition, general ultra-high molecular weight polyethylene, as the molecular weight increases, the entanglement between the molecular chains becomes difficult to unravel, so the expected effect due to the increase in molecular weight cannot be fully expressed, for example, tensile strength at break However, there was a problem that the tensile strength at break and the wear resistance were lowered even if the molecular weight was increased beyond that.

  Then, this invention is made | formed in view of the said subject, and it aims at providing the ultra-high molecular weight polyethylene cutting molding body which is excellent in abrasion resistance and chemical resistance.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained that a cutting molded body using a novel ultra-high molecular weight polyethylene particle having a specific melting behavior becomes a cutting molded body having high strength. As a result, the present invention has been completed.

That is, the present invention uses ultrahigh molecular weight polyethylene particles that satisfy at least any of the following properties (1), (2), (3), and (4), and melts at a molding temperature of 150 ° C. or higher and 250 ° C. or lower. After compression molding to obtain a melt compression molded product made of ultra high molecular weight polyethylene, the melt compression molded product made of ultra high molecular weight polyethylene is cut to satisfy at least any of the following characteristics (1) and (4) The present invention relates to a method for producing an ultra-high molecular weight polyethylene cutting-molded body .
(1) Intrinsic viscosity ([η]) is 15 dl / g or more and 60 dl / g or less,
(2) The bulk density is 130 kg / m ³ or more and 700 kg / m ³ or less,
(3) 1st scan melting point (Tm ₁ ) when the temperature was raised from 0 ° C. to 230 ° C. (1st scan) with a differential scanning calorimeter (DSC ), then 5 When the temperature is lowered to −20 ° C. at a temperature lowering rate of 10 ° C./min after standing for 5 minutes, and after standing for 5 minutes, the temperature is raised again from −20 ° C. to 230 ° C. at a temperature rising rate of 10 ° C./min (2nd scan). The 2nd scan melting point (Tm ₂ ) was measured, and the difference between the Tm ₁ and the Tm ₂ ( ΔTm = Tm ₁ −Tm ₂ ) was 11 ° C. or higher and 30 ° C. or lower.
(4) The titanium content is 0.2 ppm or less or the measurement detection limit or less.

  The present invention is described in detail below.

The ultrahigh molecular weight polyethylene cutting molded body of the present invention has at least (1) an intrinsic viscosity ([η]) of 15 dl / g or more and 60 dl / g or less, and (2) a bulk density of 130 kg / m ³ or more and 700 kg / m ³ or less. (3) With a differential scanning calorimeter (DSC), the melting point (Tm ₁ ) of 1st scan when the temperature was raised from 0 ° C. to 230 ° C. at a rate of 10 ° C./min (1st scan), After standing for 5 minutes, the temperature was lowered to −20 ° C. at a temperature lowering rate of 10 ° C./min. After standing for 5 minutes, the temperature was raised again from −20 ° C. to 230 ° C. at a temperature rising rate of 10 ° C./min (2nd scan). Each of the 2nd scan melting points (Tm ₂ ) was measured, and the difference between the Tm ₁ and the Tm ₂ (ΔTm = Tm ₁ −Tm ₂ ) was 11 ° C. or higher and 30 ° C. or lower. Using high molecular weight polyethylene particles, It is made by machining.

  The ultra high molecular weight polyethylene particles are those in which ultra high molecular weight polyethylene has a particle shape, and ultra high molecular weight polyethylenes belong to a category called polyethylene, for example, ultra high molecular weight ethylene homopolymers; Ultra high molecular weight ethylene such as molecular weight ethylene-propylene copolymer, ultra high molecular weight ethylene-1-butene copolymer, ultra high molecular weight ethylene-1-hexene copolymer, ultra high molecular weight ethylene-1-octene copolymer an α-olefin copolymer; and the like.

  The ultra high molecular weight polyethylene particles (1) have an intrinsic viscosity ([η]) of 15 dl / g or more and 60 dl / g or less, and particularly have excellent moldability and physical properties when formed into a cut molded body. Since it becomes a thing, it is preferable that it is 15 dl / g or more and 50 dl / g or less. Here, when the intrinsic viscosity is less than 15 dl / g, the obtained molded article is inferior in wear resistance, heat resistance, strength, and the like. On the other hand, when the intrinsic viscosity exceeds 60 dl / g, the fluidity at the time of molding is inferior, so that it becomes difficult to mold the base material before cutting molding. The intrinsic viscosity is measured at 135 ° C. using a Ubbelohde viscometer, for example, in a solution having a polymer concentration of 0.0005 to 0.01% using orthodichlorobenzene, decahydronaphthalene, tetrahydronaphthalene or the like as a solvent. It can be measured by a method.

In addition, the ultra high molecular weight polyethylene particles (2) have a bulk density of 130 kg / m ³ or more and 700 kg / m ³ or less, and are excellent in workability in forming a base material before cutting and molding. it is preferably ³ or more 600 kg / ^{m 3} or less. Here, when the bulk density is less than 130 kg / m ³ , problems such as a significant decrease in operability such as a decrease in fluidity of particles, a decrease in the filling rate in storage equipment, storage containers, and hoppers occur. It becomes easy to do. On the other hand, when the bulk density exceeds 700 kg / m ³ , the workability in forming the base material is inferior, and problems such as deterioration of physical properties of the obtained base material and the cut molded body are likely to occur. The bulk density can be measured by a method based on, for example, JIS K6760 (1995).

The ultra-high molecular weight polyethylene particles are (3) melting point of 1st scan when the temperature is raised from 0 ° C. to 230 ° C. (1st scan) at a heating rate of 10 ° C./min with a differential scanning calorimeter (DSC). (Tm ₁ ) After that, after being left for 5 minutes, the temperature was lowered to −20 ° C. at a temperature lowering rate of 10 ° C./min. After being left for 5 minutes, again from −20 ° C. to 230 ° C. at a temperature rising rate of 10 ° C./min. The melting point (Tm ₂ ) of the 2nd scan when the temperature was raised (2nd scan) was measured, and the difference between the Tm ₁ and the Tm ₂ (ΔTm = Tm ₁ -Tm ₂ ) was 11 ° C. or higher and 30 ° C. or lower, In particular, ΔTm is preferably 11 ° C. or higher and 15 ° C. or lower because an ultrahigh molecular weight polyethylene cutting molded body having an excellent balance of heat resistance, mechanical strength, and moldability is obtained. Here, when ΔTm is less than 11 ° C., the obtained molded article is inferior in heat resistance, strength, and the like. On the other hand, when ΔTm exceeds 30 ° C., not only the molding processability when the obtained ultrahigh molecular weight polyethylene particles are used as a base material is inferior, but the resulting molded article is also inferior in physical properties.

In general polyethylene, an ethylene homopolymer belonging to high-density polyethylene is known as a 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 ultra high molecular weight polyethylene particles used in the cutting molded body of the present invention have an extremely high melting point (Tm) as compared with conventionally known polyethylene. For example, if it is an ethylene homopolymer , Tm ₁ has an extremely high melting point exceeding 140 ° C. The ultra high molecular weight polyethylene particles are highly crystallized due to the orientation of polyethylene molecular chains, etc., so the difference between Tm ₁ and Tm ₂ when measured with a differential scanning calorimeter (DSC). A certain ΔTm is considered to be an extremely large difference of 11 ° C. or more and 30 ° C. or less.

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

Since the ultra high molecular weight polyethylene particles can provide a tougher ultra high molecular weight polyethylene cutting-molded body, (5) after heating and compressing at a press temperature of 190 ° C. and a press pressure of 20 MPa, the (3 ) Measured at a mold temperature lower by 10 ° C. to 30 ° C. than the melting point (Tm ₂ ) measured by 2nd scan, and the tensile strength at break (TS (MPa)) of the sheet satisfies the following relational expression (a) It is preferable that it is possible to provide a cutting molded body made of ultrahigh molecular weight polyethylene that is further tough, excellent in mechanical strength and wear resistance, and therefore satisfies the following relational expression (c). preferable.
TS ≧ 1.35 × Tm ₂ −130 (a)
1.35 × Tm ₂ −130 ≦ TS ≦ 2 × Tm ₂ −175 (c)
The tensile strength at break of general polyethylene is as low as about 45 MPa even with the highest density polyethylene. Further, conventional ultra-high molecular weight polyethylene has not been able to make full use of its high molecular weight, and the tensile strength at break was equivalent to that of general polyethylene, and did not exceed 50 MPa. For this reason, a method has been adopted in which the orientation is increased by cutting and molding at a high draw ratio to increase the strength.

  However, since the ultra high molecular weight polyethylene particles used in the cutting molded body of the present invention are appropriately entangled with the polymer chains, even if the ultra high molecular weight polyethylene region has an intrinsic viscosity of more than 15 dl / g, the molecular weight is further increased. Even if it raises, tensile fracture strength does not fall, but rather shows the tendency to improve further. And, as the ultra-high molecular weight polyethylene particles used for the cutting molded body of the present invention, the strength becomes more excellent when formed into a molded body, so if it belongs to the region of high density polyethylene, the above (5) The measured tensile strength at break is preferably 40 MPa or more, more preferably 50 MPa or more.

  In addition, there is no restriction | limiting in particular as measurement conditions of tensile breaking strength, For example, test pieces, such as a strip shape and a dumbbell type | mold of thickness 0.1-5mm and width 1-50mm, are used for the tensile speed of 1 mm / min-500 mm / min. A method of measuring by speed can be exemplified.

Since the ultra-high molecular weight polyethylene particles have a relatively low content of low molecular weight components, the polymer chains can be appropriately entangled, and become an ultra-high molecular weight polyethylene cutting molded body that is particularly excellent in heat resistance. 6) When the heat-compressed sheet is melt-stretched at a temperature 20 ° C. higher than the melting point (Tm ₂ ) of the 2nd scan measured in (3) above, the breaking stress (MTS (MPa)) is 2 MPa or more. It is preferable that it has 3 MPa or more.

  Note that general polyethylene having a molecular weight of 500,000 or less has high fluidity at a temperature 20 ° C. higher than the melting point (Tm), and the molded body is deformed by its own weight, so that it cannot be melt-stretched. In addition, the conventional ultrahigh molecular weight polyethylene can be melt-stretched even at a temperature 20 ° C. higher than the melting point (Tm), but strain hardening does not occur due to the low molecular weight component contained, and the stress remains low. It was ruptured by a stress of around 1 MPa and was inferior in heat resistance.

  And there is no restriction | limiting as a shaping | molding condition of the heat compression molding sheet | seat used for melt drawing, For example, it is the conditions of the press temperature of 100-250 degreeC, and the press pressure of 5-50 MPa, Among them, especially the heat compression described in said (5). A molding method can be exemplified. Examples of the melt stretching method include a method of stretching a test piece such as a strip shape having a thickness of 0.1 to 5 mm and a width of 1 to 50 mm and a dumbbell shape at a tensile speed of 1 mm / min to 500 mm / min. be able to. Furthermore, as the rupture stress at the time of melt stretching, strain hardening occurs, if the stress increases with stretching, the maximum value is the rupture stress, strain hardening does not occur, and if the stress does not increase even after stretching, The stress in the flat region after yielding was taken as the breaking stress.

Since the ultra high molecular weight polyethylene particles are a particularly high heat resistant polyethylene cut-molded body, (7) stress at break (MTS (MPa)) when melt stretched as measured in (6) above. ) And the intrinsic viscosity ([η]) preferably satisfy the following relational expression (b), and in particular, satisfy the following relational expression (d) because the melt stretchability and moldability are excellent. It is preferable.
MTS ≧ 0.11 × [η] (b)
0.11 × [η] ≦ MTS ≦ 0.32 × [η] (d)
The ultra high molecular weight polyethylene particles are particularly excellent in fluidity as a powder and become an ultra high molecular weight polyethylene cutting molded body having excellent moldability and physical properties. (8) The average particle size is 1 μm or more and 1000 μm or less. Some are preferred. The average particle size can be measured by a method such as a sieving test method using a standard sieve defined in JIS Z8801, for example.

  As a method for producing the ultra high molecular weight polyethylene particles used in the ultra high molecular weight polyethylene cutting molded body of the present invention, any method may be used as long as the ultra high molecular weight polyethylene particles can be produced. Examples thereof include a method for homopolymerization of ethylene and copolymerization of ethylene and other olefins using a catalyst. Examples of the α-olefin in this case include propylene, 1-butene and 4-methyl-1-pentene. , 1-hexene, 1-octene and the like. Examples of the polymerization method include a solution polymerization method, a bulk polymerization method, a gas phase polymerization method, a slurry polymerization method, and the like. Among them, the production of ultra high molecular weight polyethylene particles having a particularly uniform particle shape is possible. Ultra-high-molecular-weight polyethylene particles capable of providing ultra-high-molecular-weight polyethylene cuttings with high melting point and high crystallinity, and excellent mechanical strength, heat resistance, and wear resistance The slurry polymerization method is preferable because it can be produced. Further, the solvent used in the slurry polymerization method may be any organic solvent that is generally used, such as benzene, toluene, xylene, pentane, hexane, heptane, etc., and liquefied gas such as isobutane and propane, Olefins such as propylene, 1-butene, 1-octene and 1-hexene can also be used as a solvent.

  Further, as the polyethylene production catalyst used for producing the ultra high molecular weight polyethylene particles, any catalyst can be used as long as the ultra high molecular weight polyethylene particles can be produced, for example, at least a transition metal compound. Examples thereof include (A), a metallocene catalyst obtained from an organically modified clay (B) modified with an aliphatic salt and an organoaluminum compound (C).

  Examples of the transition metal compound (A) include a transition metal compound having a (substituted) cyclopentadienyl group and a (substituted) fluorenyl group, and 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, etc. can be mentioned. Examples of the transition metal in this case include zirconium, hafnium, etc. Since it is possible to efficiently produce molecular weight polyethylene particles, a zirconium compound having a (substituted) cyclopentadienyl group and an amino group-substituted fluorenyl group, a (substituted) cyclopentadienyl group and an amino group-substituted fluorenyl group It is preferable that it is a hafnium compound.

  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 Nium dichloride, 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) ( 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 (cyclopentadi) Enyl) (2,7-bis (dimethylamino) -9-fluorenyl) zirconium dichloride, diphenylmethylene (cyclopentadienyl) (2,7-bis (diethylamino) -9-fluorenyl) zyl Nium 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 obtained by converting these dichloro compounds to dimethyl, diethyl, dihydro, diphenyl, and dibenzyl compounds, and hafnium compounds obtained by converting zirconium of these compounds to hafnium A thing etc. can be illustrated.

  Examples of the organically modified clay (B) modified with the aliphatic salt include N, N-dimethyl-behenylamine hydrochloride, N-methyl-N-ethyl-behenylamine hydrochloride, N-methyl-Nn- Propyl-behenylamine hydrochloride, N, N-dioleyl-methylamine hydrochloride, N, N-dimethyl-behenylamine hydrofluoride, N-methyl-N-ethyl-behenylamine hydrofluoride, N- Methyl-Nn-propyl-behenylamine hydrofluorate, 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-be Nylamine hydroiodide, N-methyl-N-ethyl-behenylamine hydroiodide, N-methyl-Nn-propyl-behenylamine hydroiodide, N, N-dioleyl-methylamine iodide Hydronate, N, N-dimethyl-behenylamine sulfate, N-methyl-N-ethyl-behenylamine sulfate, N-methyl-Nn-propyl-behenylamine sulfate, N, N-dioleoyl-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 fluoride Hydronate, 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 , P-diethyl-behenylphosphine sulfate, and aliphatic phosphonium salts such as P, P-dipropyl-behenylphosphine sulfate;

Further, 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 two-dimensionally continuous. A layer called a silicate layer formed by combining a sheet and an octahedron sheet in which an alumina octahedron, a magnesia octahedron, etc. are two-dimensionally continuous in a 1: 1 or 2: 1 layer is formed to overlap. Some of the silica tetrahedrons are replaced with the same type of Si by Al, alumina octahedron Al by Mg, magnesia octahedron Mg by Li, etc. It is known that cations such as Na ⁺ and Ca ²⁺ exist between the 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 (B) can be obtained by introducing the aliphatic salt between layers of the clay compound to form an ionic complex. In preparing the organically modified clay (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 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. 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.

  Moreover, there is no restriction | limiting in the particle size of the organic modified clay (B) which comprises the catalyst for polyethylene manufacture of this invention, and since it will become excellent in the efficiency at the time of catalyst preparation, and the efficiency at the time of polyethylene manufacture in 1-100 micrometers. Preferably there is. There is no limitation on the method of adjusting the particle size at that time, and large particles may be pulverized to an appropriate particle size, small particles may be granulated to an appropriate particle size, or pulverization and granulation May be combined. The particle size may be adjusted on the clay before organic modification or on the organic modified clay after modification.

  Any organoaluminum compound (C) may be used as long as it belongs to the category called organoaluminum compound, and examples thereof include alkylaluminums such as trimethylaluminum, triethylaluminum, and triisobutylaluminum. Can do.

  The transition metal compound (A) (hereinafter also referred to as component (A)) constituting the catalyst for producing polyethylene, the organically modified clay (B) (hereinafter also referred to as component (B)), and The use ratio of the organoaluminum compound (C) (hereinafter sometimes referred to as component (C)) is not subject to any limitation as long as it can be used as a catalyst for polyethylene production. Since it becomes a catalyst for polyethylene production capable of producing ultra-high molecular weight polyethylene particles with high production efficiency, the molar ratio of the component (A) to the component (C) per metal atom is the component (A): component (C). = 100: 1 to 1: 100,000 is preferable, and 1: 1 to 1: 10000 is particularly preferable. The weight ratio of the component (A) to the component (B) is preferably (A) component: (B) component = 10: 1 to 1: 10000, particularly in the range of 3: 1 to 1: 1000. It is preferable.

  Regarding the method for preparing the polyethylene production catalyst, any method may be used as long as it is possible to prepare the polyethylene production catalyst containing 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. Moreover, there is no restriction | limiting also about the order which makes these components react, and the temperature and processing time which perform this process also have no restriction | limiting. It is also possible to prepare a catalyst for polyethylene production using two or more of each of the component (A), the component (B), and the component (C).

  Polymerization conditions such as polymerization temperature, polymerization time, polymerization pressure, and monomer concentration when producing ultrahigh molecular weight polyethylene particles used in the ultra high molecular weight polyethylene cutting molded body of the present invention can be arbitrarily selected. The polymerization temperature is preferably 0 to 100 ° 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. The polyethylene particles obtained after the completion of the polymerization can be obtained by separating and recovering from the polymerization solvent by a conventionally known method and drying.

  Next, the manufacturing method of the ultra high molecular weight polyethylene cutting molded body of the present invention will be described. The cutting molded body of the present invention can be formed into a molded body by cutting a base material using the ultra high molecular weight polyethylene particles. As the base material at that time, for example, the ultra high molecular weight polyethylene particles are used. , Compression molded sheets, rod-shaped, block-shaped, columnar molded products, pipes, and the like. Examples of the compression molding method at that time include a compression molding with a compression molding machine or an extrusion molding with intermittent compression with a ram extruder. As the molding temperature for compression molding, the fusion property between the ultra-high molecular weight polyethylenes is good, and it becomes a dense base material, and the base material that is excellent in discoloration, physical properties, etc., is suppressed in oxidative deterioration, and cutting molding Since it becomes a body, 0 degreeC or more and 300 degrees C or less, Especially 100 degreeC or more and 250 degrees C or less, Furthermore, 150 degreeC or more and 250 degrees C or less are preferable.

  There is no restriction | limiting in particular as a cutting method, For example, the method of cutting a base material using a lathe, a laser cutting machine, etc. can be mentioned. Further, after rough cutting, a method such as multi-stage cutting in which finish molding is performed may be used. Furthermore, it is possible to perform heat treatment such as annealing after cutting.

  The ultra-high molecular weight polyethylene cutting molded body of the present invention includes a heat resistance stabilizer, a weather resistance stabilizer, an antistatic agent, an antifogging agent, an antiblocking agent, a slip agent, a lubricant, and a nucleating agent as long as they do not depart from the object of the present invention. Inorganic fillers or reinforcing agents such as carbon black, talc, glass powder, glass fiber, and metal powders; Organic fillers or reinforcing agents; Flame retardants; Known additives such as neutron shielding agents; Density polyethylene (HDPE), linear low density polyethylene (L-LDPE), low density polyethylene (LDPE), polypropylene resin, poly-1-butene, poly-4-methyl-1-pentene, ethylene / vinyl acetate Polymers, ethylene / vinyl alcohol copolymers, polystyrene, and these maleic anhydride grafts may be blended with such additives. The addition method, a method of blending the ultra high molecular weight polyethylene particles include ultra high molecular weight polyethylene particles, a method of blending at the time of molding, a method of preliminarily dry-blended or melt-blending, and the like.

  The ultra-high molecular weight polyethylene cutting molded body of the present invention is excellent in heat resistance, wear resistance, and chemical resistance, so it can be used for various machines such as rollers, rotating parts such as gears, medical parts such as artificial joint parts, and irregular shapes. It can be used as a member such as a rail, a pipe, a ball, or a bearing.

  The ultra-high molecular weight polyethylene cutting molded body obtained by the present invention is excellent in wear resistance, chemical resistance, etc., so it can be used for various parts such as rollers, gears and other rotating parts of various machines, medical parts such as artificial joint parts, and deformed parts. It is suitably used for rails, pipes and the like.

  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.

  A jet mill (manufactured by Seishin Enterprise Co., Ltd., (trade name) CO-JET SYSTEM α MARK III) was used for pulverizing the organically modified clay, and the particle size after pulverization was measured using a microtrack particle size distribution measuring device (manufactured by Nikkiso Co., Ltd., (Trade name) MT3000) was used to measure ethanol as a dispersant.

  Preparation of the catalyst for polyethylene production, production of polyethylene 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 intrinsic viscosity ([η]) ~
Using an Ubbelohde viscometer, ODCB (orthodichlorobenzene) was used as a solvent at 135 ° C. with an ultrahigh molecular weight polyethylene concentration of 0.005 wt%.

~ Measurement of bulk density ~
It measured by the method based on JISK6760 (1995).

~ Measurement of Tm ₁ and Tm ₂ ~
Using a differential scanning calorimeter (DSC) (product name: DSC6220, manufactured by SII Nanotechnology Co., Ltd.), the temperature was raised from 0 ° C to 230 ° C at a rate of 10 ° C / min (1st scan). The crystal melting peak (Tm ₁ ) of 1st scan was measured. Then, after standing for 5 minutes, the temperature was lowered to −20 ° C. at a temperature lowering rate of 10 ° C./min. After standing for 5 minutes, the temperature was raised again from −20 ° C. to 230 ° C. at a temperature rising rate of 10 ° C./min (2nd scan). 2nd scan crystal melting peak (Tm ₂ ) was measured. The sample amount of ultra high molecular weight polyethylene at that time was 6 mg.

-Measurement of titanium content-
The ultra high molecular weight polyethylene was incinerated, alkali melted, and the prepared solution was used to determine the titanium content in the ultra high molecular weight polyethylene using an ICP emission analyzer (manufactured by PerkinElmer Co., Ltd., (trade name) Optima 3000XL). It was measured.

~ Measurement of average particle diameter ~
Obtained when classifying 100 g of ultrahigh molecular weight polyethylene particles using 9 types of sieves defined by JIS Z8801 (openings: 710 μm, 500 μm, 425 μm, 300 μm, 212 μm, 150 μm, 106 μm, 75 μm, 53 μm) The average particle diameter was determined by measuring the particle diameter at 50% weight on an integral curve obtained by integrating the weight of the particles remaining on each sieve from the side having a large opening.

~ Preparation of sheet for evaluation of ultra high molecular weight polyethylene particles ~
The sheet for evaluation of ultrahigh molecular weight polyethylene particles used for molding the cut molded body was molded by the following method. That is, ultra high molecular weight polyethylene particles were sandwiched between polyethylene terephthalate films, preheated at 190 ° C. for 5 minutes, and then heat-cut at 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 into a dumbbell shape from a sheet for evaluation of ultrahigh molecular weight polyethylene particles (width of measurement part: 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.

-Measurement of breaking stress during melt drawing-
A sample cut into a dumbbell shape by the method described in the above measurement of tensile strength at break (10 mm in width of measurement part) was allowed to stand at 23 ° C. for 48 hours, and then a tensile tester (manufactured by A & D Co., Ltd.). , (Trade name) Tensilon UMT2.5T), a tensile test was performed at 150 ° C. with an initial length of the test piece of 10 mm and a tensile speed of 20 mm / min, and the breaking stress at the time of melt drawing was determined. When strain hardening occurs and stress increases with stretching, the maximum value is the breaking stress, and when strain hardening does not occur and stress does not increase after stretching, the stress in the flat region after yielding is the breaking stress. did.

~ Evaluation of chemical resistance ~
A roller made of ultrahigh molecular weight polyethylene prepared by cutting was immersed in 500 ml of xylene and heated at 80 ° C. for 5 hours. During the heating, the roller was removed, and the polyethylene component eluted in xylene was weighed by distilling off xylene. The smaller the elution amount, the better the chemical resistance.

~ Evaluation of wear resistance ~
A sand abrasion test was performed on a roller made of ultrahigh molecular weight polyethylene prepared by cutting. While rotating the roller at a rotation speed of 100 rpm, sand was continuously dropped from a height of 1 m to 5 hours, and the amount of wear was measured. The smaller the amount of wear, the better the wear resistance.

Production Example 1
(1) Preparation of organically modified clay 300 ml of industrial alcohol (manufactured by Nippon Alcohol Sales Co., Ltd., (trade name) Echinen F-3) and 300 ml of distilled water were placed in a 1 liter flask, and 15.0 g of concentrated hydrochloric acid and dioleylmethylamine were added. (Lion Co., Ltd., (trade name) Armin M20) 64.2 g (120 mmol) was added and heated to 45 ° C. to disperse 100 g of synthetic hectorite (Rockwood Additives, (trade name) Laponite RDS). After that, 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 600 ml of water at 60 ° C., and dried in an oven at 85 ° C. for 12 hours to obtain 160 g of organically modified clay. This organically modified clay was pulverized by a jet mill to have a median diameter of 7 μm.

(2) Preparation of catalyst suspension for polyethylene production After replacing a 300 ml flask equipped with a thermometer and a reflux tube with nitrogen, 25.0 g of the organically modified clay obtained in (1) and 108 ml of hexane were added. 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 taken out, washed twice with 200 ml of hexane, and then 200 ml of hexane was added to obtain a suspension of a catalyst for producing polyethylene (solid weight: 11.7 wt%).

(3) Production of ultra high molecular weight polyethylene particles 1.2 liters of hexane, 1.0 ml of 20% triisobutylaluminum in a 2 liter autoclave, and 356 mg of a suspension of the catalyst for polyethylene production obtained in (2) ( (Equivalent to 41.7 mg of solid content) was added, and the temperature was set to 45 ° C., and then ethylene was continuously supplied so that the partial pressure became 1.6 MPa to carry out slurry polymerization of ethylene. After 180 minutes, the pressure was released, and the slurry was filtered and dried to obtain 47.9 g of ultrahigh molecular weight polyethylene particles (1) (activity: 1150 g / g catalyst). The physical properties of the obtained ultrahigh molecular weight polyethylene particles (1) are shown in Table 1.

Production Example 2
(1) Preparation of organically modified clay Into a 1 liter flask was placed 300 ml of industrial alcohol (manufactured by Nippon Alcohol Sales, (trade name) Echinen F-3) and 300 ml of distilled water, 15.0 g of concentrated hydrochloric acid and dimethylbehenylamine (Lion After adding 42.4 g (120 mmol) of (trade name) Armin DM22D manufactured by Co., Ltd. and heating to 45 ° C., 100 g of synthetic hectorite (Rockwood Additives, (trade name) Laponite RDS) was dispersed. 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 60 ° C. water, and dried in an oven at 85 ° C. for 12 hours to obtain 125 g of an organically modified clay. This organically modified clay was pulverized by a jet mill to have a median diameter of 7 μm.

(2) Preparation of catalyst suspension for polyethylene production After replacing a 300 ml flask equipped with a thermometer and a reflux tube with nitrogen, 25.0 g of the organically modified clay obtained in (1) and 108 ml of hexane were added. 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 taken out, washed twice with 200 ml of hexane, and then 200 ml of hexane was added to obtain a suspension of a catalyst for producing polyethylene (solid weight: 12.9 wt%).

(3) Production of ultra-high molecular weight polyethylene particles In a 2 liter autoclave, 1.2 liters of hexane and 1.0 ml of 20% triisobutylaluminum, and a suspension of the catalyst for producing polyethylene obtained in (2) is 108. 7 mg (corresponding to a solid content of 14.0 mg) was added, and after raising the temperature to 65 ° C., ethylene was continuously supplied so that the partial pressure became 1.3 MPa, and ethylene slurry polymerization was performed. After 180 minutes, the pressure was released, the slurry was filtered, and dried to obtain 130 g of ultrahigh molecular weight polyethylene particles (2) (activity: 9300 g / g catalyst). The physical properties of the obtained ultrahigh molecular weight polyethylene particles (2) are shown in Table 1.

Production Example 3
(1) Preparation of solid catalyst component In a 1 liter glass flask equipped with a thermometer and a reflux tube, 50 g (2.1 mol) of metal magnesium powder and 210 g (0.62 mol) of titanium tetrabutoxide were added. Then, 320 g (4.3 mol) of n-butanol in which 0.5 g was dissolved was added at 90 ° C. over 2 hours, and the mixture was further stirred at 140 ° C. for 2 hours under a nitrogen seal while excluding generated hydrogen gas to obtain a homogeneous solution. . Then 2100 ml of hexane was added.

  90 g of this component (equivalent to 0.095 mol of magnesium) was put in a separately prepared 500 ml glass flask and diluted with 59 ml of hexane. A hexane solution (106 ml) containing isobutylaluminum dichloride (0.29 mol) at 45 ° C. was added dropwise over 2 hours and further stirred at 70 ° C. for 1 hour to obtain a solid catalyst component. The remaining unreacted substances and by-products were removed by a gradient method using hexane, and the composition was analyzed. The titanium content was 8.6 wt%.

(2) Production of ultra high molecular weight polyethylene 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 heated to 80 ° C. After the temperature increase, ethylene was continuously supplied so that the partial pressure became 0.6 MPa. After 90 minutes, the pressure was released, and the slurry was filtered and dried to obtain 170 g of ultrahigh molecular weight polyethylene (3) (activity: 51000 g / g catalyst). Table 1 shows the physical properties of the obtained ultrahigh molecular weight polyethylene (3).

実施例１
製造例１で製造した超高分子量ポリエチレン粒子（１）を、１９０℃で予備加熱した後、プレス圧力を２０ＭＰａにして２０分間、圧縮成形し、母材として角柱状の成形体を作成した。この角柱状の成形体から切削加工により長さ６ｃｍ、外径５ｃｍ、内径３ｃｍのローラーを作成した。このローラーの耐薬品性、耐摩耗性を評価した。結果を表２に示す。

Example 1
The ultrahigh molecular weight polyethylene particles (1) produced in Production Example 1 were preheated at 190 ° C. and then compression-molded for 20 minutes at a press pressure of 20 MPa to produce a prismatic shaped body as a base material. A roller having a length of 6 cm, an outer diameter of 5 cm, and an inner diameter of 3 cm was formed from the prismatic shaped body by cutting. The roller was evaluated for chemical resistance and wear resistance. The results are shown in Table 2.

Comparative Example 1
An ultrahigh molecular weight polyethylene roller was produced in the same manner as in Example 1 except that the ultrahigh molecular weight polyethylene (3) produced in Production Example 3 was used instead of the ultrahigh molecular weight polyethylene particles (1). The roller was evaluated for chemical resistance and wear resistance. The results are shown in Table 2. It was inferior in chemical resistance and wear resistance.

Comparative Example 2
Example 1 except that (trade name) Million 240M (manufactured by Mitsui Chemicals, Inc.) (hereinafter referred to as ultra high molecular weight polyethylene (4)) was used in place of the ultra high molecular weight polyethylene particles (1). Ultra high molecular weight polyethylene rollers were produced by the same method. The roller was evaluated for chemical resistance and wear resistance. The results are shown in Table 2. It was inferior in chemical resistance and wear resistance.

Example 2
An ultrahigh molecular weight polyethylene roller was produced in the same manner as in Example 1 except that the ultrahigh molecular weight polyethylene particles (2) produced in Production Example 2 were used instead of the ultrahigh molecular weight polyethylene particles (1). The roller was evaluated for chemical resistance and wear resistance. The results are shown in Table 2.

Example 3
An ultrahigh molecular weight polyethylene roller was produced in the same manner as in Example 3 except that the compression molding temperature was 220 ° C. The roller was evaluated for chemical resistance and wear resistance. The results are shown in Table 2.

  The ultra-high molecular weight polyethylene cutting molded body obtained by the present invention is excellent in wear resistance, chemical resistance, etc., so it can be used for various parts such as rollers, gears and other rotating parts of various machines, medical parts such as artificial joint parts, and balls. It can be used for various applications such as bearings.

Claims (1)

Using ultra-high molecular weight polyethylene particles satisfying at least any of the following properties (1), (2), (3), and (4), melt compression molding at a molding temperature of 150 ° C. or higher and 250 ° C. or lower and ultra-high molecular weight After forming a polyethylene melt compression molded product, the ultra high molecular weight polyethylene melt compression molded product is cut to satisfy at least any of the following characteristics (1) and (4): The manufacturing method of the cutting molding body made from ultra high molecular weight polyethylene.
(1) Intrinsic viscosity ([η]) is 15 dl / g or more and 60 dl / g or less,
(2) Bulk density is 130kg / m ³ 700 kg / m or more ³ Less than,
(3) 1st scan melting point (Tm) when the temperature was raised from 0 ° C. to 230 ° C. (1st scan) with a differential scanning calorimeter (DSC). ₁ ) After that, after 5 minutes, the temperature was lowered to −20 ° C. at a rate of 10 ° C./min. After left for 5 minutes, the temperature was raised again from −20 ° C. to 230 ° C. at a rate of 10 ° C./min ( 2nd scan melting point (Tm) ₂ ) For each Tm ₁ And the Tm ₂ Difference (ΔTm = Tm ₁ -Tm ₂ ) Is 11 ° C. or higher and 30 ° C. or lower.
(4) The titanium content is 0.2 ppm or less or the measurement detection limit or less.