Ultra-high molecular weight polyethylene powder and molded body obtained by molding the same

Abstract

An ultrahigh-molecular-weight polyethylene powder having an intrinsic viscosity IV of 1.0-33.0 dL / g, the average value TS of the swelling start temperature of the ultrahigh-molecular-weight polyethylene powder as derived according to a specific method being 90-130°C.

Description

[Technical Field]

[0001] The present invention relates to an ultra-high molecular weight polyethylene powder and a molded article obtained by molding the same. [Background technology]

[0002] Polyethylene is used in a wide variety of applications, including films, sheets, microporous membranes, fibers, foams, and pipes. Polyethylene is used because it is easy to melt-process, and the resulting molded articles have high mechanical strength and excellent chemical resistance and rigidity. Among these, ultra-high molecular weight polyethylene has a large molecular weight, which gives it greater mechanical strength, excellent sliding properties and abrasion resistance, as well as excellent chemical stability and long-term reliability.

[0003] However, ultra-high molecular weight polyethylene has low fluidity even when melted at a temperature equal to or higher than its melting point. Therefore, various methods are applied to the polyethylene, such as a compression molding method in which polyethylene powder is compressed and molded under heat and then cut, or a molding method in which the polyethylene is dissolved in a solvent such as liquid paraffin, stretched, and then the solvent is removed to form the polyethylene into a sheet or thread shape.

[0004] Ultra-high molecular weight polyethylene is molded in powder form, but compared to pellets, the powder has a larger surface area and contains fine pores.

[0005] Regarding the pore state of the polyethylene powder, for example, Patent Document 1 discloses a polyethylene powder that dissolves quickly in a solvent and gives a molded product with little undissolved matter by adjusting the specific surface area determined by the BET method and the pore volume determined by mercury intrusion porosimetry to appropriate ranges.

[0006] Furthermore, for example, Patent Document 2 discloses a polyethylene powder that can obtain a molded product with little undissolved matter by adjusting the ratio of the median diameter to the mode diameter of pores measured by mercury intrusion porosimetry to an appropriate range.

[0007] In recent years, polyethylene powder has been proposed that has excellent moldability and allows high-quality molded articles to be obtained.

[0008] For example, Patent Document 3 discloses a polyethylene powder that has excellent solubility and can improve productivity and product quality in processing and molding (particularly wet extrusion molding) by simultaneously imparting a predetermined particle size distribution and a predetermined swelling ratio to the polyethylene powder.

[0009] Furthermore, for example, Patent Document 4 discloses a polyethylene polymer powder in which the intrinsic viscosity IV and the contents of Al, Mg, and Si are controlled within specific ranges, thereby improving oxidation resistance and effectively improving the uniformity and smoothness of the thin film.

[0010] Furthermore, for example, Patent Document 5 discloses an ethylene-based polymer that, by incorporating a non-magnetic substance that satisfies specific conditions, reduces entanglement of the ethylene-based polymer when processed and stretched, and when made into a high-strength fiber, has excellent low-temperature tensile strength, and when made into a microporous film, has excellent film shrinkage rate and low-temperature puncture strength. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-088773 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-145306 [Patent Document 3] Japanese Patent Application Publication No. 2019-019265 [Patent Document 4] Japanese Patent Application Publication No. 2019-070117 [Patent Document 5] Japanese Patent Application Publication No. 2019-123777 Summary of the Invention [Problem to be solved by the invention]

[0012] As described above, ultra-high molecular weight polyethylene powder has a larger surface area than pellets and contains fine pores. Therefore, the shape, surface condition, crystalline state, pore state, etc. of the powder change during heating. Therefore, when molding ultra-high molecular weight polyethylene powder, it is necessary to adjust the temperature appropriately and perform processing such as melting and compression. When ultra-high molecular weight polyethylene powder is compression molded, if the preheating temperature before compression is not appropriate, air bubbles tend to remain in the molded product, or the molded product tends to have residual distortion and deform after cooling.

[0013] The polyethylene powder described in Patent Document 1 only has its powder properties adjusted, such as specific surface area and pore volume, and the powder properties change significantly at the temperature at which it actually melts or dissolves, leaving room for improvement in moldability.

[0014] Furthermore, the polyethylene powder described in Patent Document 2 only specifies the pore size of the powder, and the pore size changes significantly during the heating process, so there is room for improvement in moldability, and it may be difficult to obtain a uniform molded product.

[0015] Furthermore, although the polyethylene powders described in Patent Documents 3 to 5 have excellent moldability, there is room for improvement as no study has been conducted on the moldability when the powders are previously swollen at low temperatures.

[0016] The present invention has been made in view of the above circumstances, and aims to provide an ultra-high molecular weight polyethylene powder that exhibits excellent moldability when pre-swollen at low temperatures, and a high-quality molded article (e.g., a separator for a secondary battery and a fiber) obtained by molding the powder. [Means for solving the problem]

[0017] As a result of intensive research into solving the above problems, the present inventors have found that the particle diameter is D 10 , D 50 and D 90The present inventors have found that the above problems can be solved by controlling the swelling initiation temperature of the ultra-high molecular weight polyethylene powder within a specific range, and have completed the present invention.

[0018] That is, the present invention is as follows. [1] The intrinsic viscosity IV is 1.0 dL / g or more and 33.0 dL / g or less, The average swelling temperature T obtained by the following methods 1 and 2 S Ultra-high molecular weight polyethylene powder having a temperature of 90°C or higher and 130°C or lower. [Method 1;D 10 , D 50 and D 90 Measurement method] The particle size of the target ultra-high molecular weight polyethylene powder was measured using a laser particle size distribution analyzer with methanol as a dispersion medium, and a cumulative particle size distribution was created from the small particle size side based on the measurement. The particle sizes at 10%, 50%, and 90% of the cumulative size were then designated D 10 , D 50 and D 90 Let's say. [Method 2; Swelling start temperature T 10 , T 50 , T 90 Measurement method and its average value T S Calculation method] Particle diameter is D 10 The swelling start temperature T of the powder is 10 First, determine the major axis diameter and minor axis diameter (the shortest distance between parallel lines in the plane view of the particle observed using an optical microscope is the minor axis diameter of the particle, and the longest distance between parallel lines in the perpendicular direction is the major axis diameter of the particle). 10One particle of ultra-high molecular weight polyethylene powder was randomly selected while checking the particle size within a ±10% range using an optical microscope. One particle of the selected ultra-high molecular weight polyethylene powder (hereinafter also referred to as the "measured particle") was placed on a glass slide. 0.05 mL of liquid paraffin was then dripped onto the particle using a 1 mL syringe, and a cover glass was then placed on top to sandwich the particle. The slide was then placed on a heat stage and heated from room temperature to 150°C under the following heating conditions. Images of the particle's appearance during heating were taken every 6 seconds using a camera-equipped optical microscope. The equivalent circle diameter of the particle was calculated from each image obtained, and the minimum temperature at which the equivalent circle diameter of the particle increased by 1% or more within the temperature range of 80°C to 150°C was determined as the swelling initiation temperature of the particle, based on the equivalent circle diameter of the particle at 80°C. Ten measurements were taken, and the average of these was determined as the swelling initiation temperature T 10 Let's say. Next, the particle diameter is D 50 The swelling onset temperature T of ultra-high molecular weight polyethylene powder is 50 , and particle diameter is D 90 The swelling onset temperature T of ultra-high molecular weight polyethylene powder is 90 Regarding the swelling starting temperature T 10 Similarly, the major and minor axis diameters are D 50 Ultra-high molecular weight polyethylene powder within the range of ±10%, and the major and minor axis diameters are D 90 Measured using ultra-high molecular weight polyethylene powder within a range of ±10%. Finally, the swelling starting temperature T 10 , T 50 , T 90 The average value of T S is calculated as follows:

number

[10] The molded article according to [8], wherein the molded article is a fiber.

[11] A method for producing the ultra-high molecular weight polyethylene powder according to any one of [1] to [7], A step of polymerizing ethylene by mixing a comonomer in ethylene at a gas phase concentration of 0.01 to 0.05 mol% when producing an ethylene polymer; A method for producing ultra-high molecular weight polyethylene powder, comprising a step of drying the polymerized powder at 100°C or higher.

[12] A method for producing the ultra-high molecular weight polyethylene powder according to any one of [1] to [7], A method for producing ultra-high molecular weight polyethylene powder, comprising a polymerization step of carrying out polymerization in a state in which 30 to 50 mass % of a plasticizer is added to a polymerization solvent.

[13] removing the plasticizer from the powder after the polymerization step is completed; and a drying step of reducing the catalytic activity during polymerization to 5000 (g-PE / g-catalyst) or less and drying the polymerized powder at 70°C or less; The method for producing an ultra-high molecular weight polyethylene powder according to

[12] ,

[14] The method for producing an ultra-high molecular weight polyethylene powder according to

[12] or

[13] , wherein the plasticizer is liquid paraffin. [Effects of the Invention]

[0019] According to the present invention, it is possible to obtain an ultra-high molecular weight polyethylene powder that has excellent moldability when pre-swollen at low temperatures, and a high-quality molded product (e.g., a separator for a secondary battery and a fiber) obtained by molding the ultra-high molecular weight polyethylene powder. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, a mode for carrying out the present invention (hereinafter also referred to as "the present embodiment") will be described in detail. Note that the present invention is not limited to the present embodiment, and various modifications can be made within the scope of the gist of the present invention.

[0021] [Ultra-high molecular weight polyethylene powder] The ultra-high molecular weight polyethylene powder of this embodiment (hereinafter also simply referred to as "powder") has an intrinsic viscosity IV of 1.0 dL / g or more and 33.0 dL / g or less, preferably 1.5 dL / g or more and 31.0 dL / g or less, and more preferably 2.4 dL / g or more and 29.0 dL / g or less. The ultra-high molecular weight polyethylene powder of the present embodiment has an intrinsic viscosity IV of not less than the lower limit, thereby further improving the strength, and has an intrinsic viscosity IV of not more than the upper limit, thereby further improving the moldability.

[0022] Furthermore, when the ultra-high molecular weight polyethylene powder of this embodiment is used for molding, for example, a separator for a secondary battery, the intrinsic viscosity IV is preferably 1.0 dL / g or more and 13.0 dL / g or less, more preferably 1.5 dL / g or more and 11.5 dL / g or less, and even more preferably 2.4 dL / g or more and 9.5 dL / g or less. Secondary battery separators obtained by molding ultra-high molecular weight polyethylene powder having an intrinsic viscosity IV within the above range tend to have excellent film strength and heat shrinkability.

[0023] Furthermore, when the ultra-high molecular weight polyethylene powder of this embodiment is used for, for example, a fiber molding, the intrinsic viscosity IV is preferably 13.5 dL / g or more and 33.0 dL / g or less, more preferably 15.0 dL / g or more and 31.0 dL / g or less, and even more preferably 16.5 dL / g or more and 29.0 dL / g or less. Fibers obtained by molding an ultra-high molecular weight polyethylene powder having an intrinsic viscosity IV within the above range (for example, by molding in a conventional manner or by molding after pre-swelling at a low temperature) tend to have excellent yarn strength.

[0024] Methods for controlling the intrinsic viscosity IV within the above range include, but are not limited to, changing the polymerization temperature of the reactor when homopolymerizing ethylene or copolymerizing ethylene with a copolymerizable olefin. The intrinsic viscosity IV tends to decrease as the polymerization temperature increases, and tends to increase as the polymerization temperature decreases. Another method for controlling the intrinsic viscosity IV within the above range includes, but is not limited to, changing the type of organometallic compound used as a co-catalyst when homopolymerizing ethylene or copolymerizing ethylene with a copolymerizable olefin. Another method for controlling the intrinsic viscosity IV within the above range includes, but is not limited to, adding a chain transfer agent when homopolymerizing ethylene or copolymerizing ethylene with a copolymerizable olefin. Adding a chain transfer agent tends to lower the intrinsic viscosity IV of the ultra-high molecular weight polyethylene produced at the same polymerization temperature. Examples of chain transfer agents include, but are not limited to, one or more compounds selected from the group consisting of hydrogen, organoaluminum compounds, organoboron compounds, organozinc compounds, organosilicon compounds, organocadmium compounds, and organolead compounds. Hydrogen is particularly preferred. In this embodiment, the intrinsic viscosity IV can be determined by the method described in the examples below.

[0025] The ultra-high molecular weight polyethylene powder of the present embodiment is preferably a powder made of an ethylene homopolymer and / or a copolymer (hereinafter also referred to as an "ethylene polymer") of ethylene and an olefin copolymerizable with ethylene (hereinafter also referred to as a "comonomer").

[0026] The olefin copolymerizable with ethylene is not particularly limited, but specific examples thereof include α-olefins having 3 to 15 carbon atoms, cyclic olefins having 3 to 15 carbon atoms, and olefins represented by the formula CH═CHR 1 (where R 1is an aryl group having 6 to 12 carbon atoms.) and at least one comonomer selected from the group consisting of linear, branched or cyclic dienes having from 3 to 15 carbon atoms. Among these, α-olefins having from 3 to 15 carbon atoms are preferred.

[0027] The α-olefin is not particularly limited, but examples thereof include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, and 1-tetradecene.

[0028] The ultra-high molecular weight polyethylene powder of this embodiment is 13 The comonomer content measured by C-NMR is preferably 1.0 mol% or less, more preferably 0.1 mol% or less, and even more preferably 0 mol%. When the comonomer content of the ultra-high molecular weight polyethylene powder of this embodiment is within this range, decomposition tends to be suppressed, and the strength of molded articles obtained by molding the ultra-high molecular weight polyethylene powder tends to be improved.

[0029] [Swelling temperature of ultra-high molecular weight polyethylene powder] The ultra-high molecular weight polyethylene powder of the present embodiment has an average swelling onset temperature T S is 90°C or higher and 130°C or lower, preferably 90°C or higher and 125°C or lower, and more preferably 90°C or higher and 120°C or lower. [Method 1;D 10 , D 50 and D 90 Measurement method] The particle size of the target ultra-high molecular weight polyethylene powder was measured using a laser particle size distribution analyzer with methanol as a dispersion medium, and a cumulative particle size distribution was created from the small particle size side based on the measurement. The particle sizes at 10%, 50%, and 90% of the cumulative size were then designated D 10 , D 50 and D 90 Let's say. [Method 2; Swelling start temperature T10 , T 50 , T 90 Measurement method and its average value T S Calculation method] Particle diameter is D 10 The swelling start temperature T of the powder is 10 First, determine the major axis diameter and minor axis diameter (the shortest distance between parallel lines in the plane view of the particle observed using an optical microscope is the minor axis diameter of the particle, and the longest distance between parallel lines in the perpendicular direction is the major axis diameter of the particle). 10 One particle of ultra-high molecular weight polyethylene powder was randomly selected while checking the particle size within a ±10% range using an optical microscope. One particle of the selected ultra-high molecular weight polyethylene powder (hereinafter also referred to as the "measured particle") was placed on a glass slide. 0.05 mL of liquid paraffin was then dripped onto the particle using a 1 mL syringe, and a cover glass was then placed on top to sandwich the particle. The slide was then placed on a heat stage and heated from room temperature to 150°C under the following heating conditions. Images of the particle's appearance during heating were taken every 6 seconds using a camera-equipped optical microscope. The equivalent circle diameter of the particle was calculated from each image obtained, and the minimum temperature at which the equivalent circle diameter of the particle increased by 1% or more within the temperature range of 80°C to 150°C was determined as the swelling initiation temperature of the particle, based on the equivalent circle diameter of the particle at 80°C. Ten measurements were taken, and the average of these was determined as the swelling initiation temperature T 10 Let's say. Next, the particle diameter is D 50 The swelling onset temperature T of ultra-high molecular weight polyethylene powder is 50 , and particle diameter is D 90 The swelling onset temperature T of ultra-high molecular weight polyethylene powder is 90 Regarding the swelling starting temperature T 10 Similarly, the major and minor axis diameters are D 50 Ultra-high molecular weight polyethylene powder within the range of ±10%, and the major and minor axis diameters are D 90 Measured using ultra-high molecular weight polyethylene powder within a range of ±10%. Finally, the swelling starting temperature T 10 , T 50 , T 90 The average value of T S is calculated as follows:

number

[0030] The ultra-high molecular weight polyethylene powder of the present embodiment has a particle diameter of D 10 , D 50 and D 90 When the average value of the swelling onset temperature of the ultra-high molecular weight polyethylene powder is within the above range, for example, when wet extruding fibers (e.g., high-strength fibers) or secondary battery separators (e.g., microporous membranes), the pre-swelling temperature can be set lower than that of conventional polyethylene, and as a result, the energy required for wet extrusion can be reduced, thereby reducing the environmental load. The ultra-high molecular weight polyethylene powder of this embodiment has an intrinsic viscosity IV within the above range and a particle diameter D 10 , D 50 and D 90 When the average swelling onset temperature of the ultra-high molecular weight polyethylene powder is within the above range, the powder exhibits excellent molding processability when it is previously swollen at a low temperature during wet extrusion processing, and therefore it is possible to obtain high-quality molded products, such as separators for secondary batteries with reduced number of defects and thickness variations, and fibers with reduced number of lumps and unevenness in diameter.

[0031] Particle diameter is D 10 , D 50 and D 90The method for controlling the average swelling onset temperature of the ultra-high molecular weight polyethylene powder within the above range is not particularly limited, but examples include a method in which, when producing an ethylene polymer, a very small amount of comonomer (0.01 to 0.05 mol% in terms of gas phase concentration) is mixed into ethylene, polymerized, and the polymerized powder is dried at 100°C or higher; and a method in which polymerization is carried out in a state in which 30 to 50 mass% of a plasticizer is added to the polymerization solvent, the plasticizer is removed from the powder after polymerization is completed, the catalytic activity during polymerization (weight of polyethylene obtained per unit weight of catalyst) is set to 5,000 (g-PE / g-catalyst) or less, and the polymerized powder is dried at 70°C or less. The plasticizer is not particularly limited, and examples thereof include non-volatile solvents capable of forming a homogeneous solution at or above the melting point of the polyolefin, such as hydrocarbons such as liquid paraffin and paraffin wax; esters such as dioctyl phthalate and dibutyl phthalate; and higher alcohols such as oleyl alcohol and stearyl alcohol. Among plasticizers, liquid paraffin is preferred when the polyolefin resin is polyethylene and / or polypropylene, because it has high compatibility with these resins, and when the molten mixture is stretched, interfacial peeling between the resin and the plasticizer is unlikely to occur, making it easier to perform uniform stretching.

[0032] By the above method, the particle diameter is D 10 , D 50 and D 90 The mechanism by which the average swelling initiation temperature of the ultra-high molecular weight polyethylene powder can be controlled within the above range is not clear, but the present inventors presume it as follows. When polyethylene powder is impregnated with a plasticizer, the plasticizer penetrates (dissolves) into the polyethylene powder, causing it to swell. Because the plasticizer cannot easily penetrate the crystalline portion of the polyethylene powder, it is believed to penetrate into the amorphous portion. It has been confirmed that the crystal long period of polyethylene powder actually elongates as it swells. In other words, swelling is thought to be a phenomenon in which the plasticizer penetrates between the lamellar crystals of the polyethylene powder and pushes open the amorphous portion. Meanwhile, tie molecules that connect the lamellar crystals are present between the lamellar crystals. Because tie molecules hold the lamellar crystals together, they are thought to provide resistance to swelling. The swelling onset temperature can be controlled by the number and / or tension of tie molecules. The fewer the number of tie molecules and / or the more relaxed the tie molecules, the easier it is for the plasticizer to penetrate into the amorphous portion, resulting in increased swelling.

[0033] It has been reported that the number of tie molecules increases with increasing lamellar thickness uniformity and crystallinity closer to 50% (Satoshi Hosoda and Yoshinobu Nozue, "Structural Factors Determining the Thickness Distribution of Polyethylene Lamellar Crystals," Proceedings of the Polymer Science and Technology Association, November 2014, Vol. 71, p. 484). In other words, the more nonuniform the lamellar thickness and the higher the crystallinity, the fewer tie molecules there are. Specific methods for achieving nonuniform lamellar thickness and increasing crystallinity are not particularly limited. For example, by mixing a very small amount of comonomer into ethylene and polymerizing it, lamellar crystals consisting of only homopolyethylene and lamellar crystals containing copolymer are mixed, resulting in nonuniform lamellar thickness. Furthermore, by performing the drying process in the polyethylene powder manufacturing process under high temperature conditions, high crystallinity can be achieved.

[0034] Furthermore, to reduce (relax) the tension of the tie molecules, it is necessary to polymerize them so that they become relaxed during the polymerization process and to devise a method to prevent the tie molecules from becoming tense during the polymerization and drying processes. Specific methods for polymerizing them so that the tie molecules become relaxed are not particularly limited, but one example is a method in which polymerization is carried out in a state in which approximately 30 to 50 mass% of a plasticizer is added to the polymerization solvent, and then the plasticizer is removed from the polyethylene powder. In the polyethylene powder polymerized in this way, the plasticizer is present from the beginning in the amorphous regions between the lamellar crystals, and the tie molecules tend to be long. Removing this plasticizer after polymerization with hexane or other methods can yield polyethylene powder with relaxed tie molecules.

[0035] Furthermore, specific methods for preventing the tension of tie molecules during the polymerization process include, but are not limited to, a method of reducing the catalytic activity (weight of polyethylene obtained per unit weight of catalyst) to 5000 (g-PE / g-catalyst) or less. Because the polyethylene polymerization reaction occurs at the active site of the catalyst, i.e., inside the polyethylene powder, high catalytic activity tends to increase the internal stress of the polyethylene powder, distorting the crystalline structure and increasing the tension of the tie molecules. Therefore, reducing the catalytic activity to 5000 (g-PE / g-catalyst) or less can suppress the tension of tie molecules. The catalytic activity can be controlled by the polymerization pressure or the amount of active species added to the catalyst.

[0036] Furthermore, specific methods for preventing tensioning of tie molecules during the drying process include, but are not limited to, keeping the drying temperature below 70°C. Drying polyethylene powder at high temperatures causes tensioning of tie molecules due to crystal rearrangement. Therefore, by keeping the drying temperature below 70°C and suppressing crystal rearrangement, tensioning of tie molecules can be suppressed.

[0037] In addition, the ultra-high molecular weight polyethylene powder of the present embodiment has a particle diameter of D 10 , D 50 and D 90The standard deviation s (hereinafter also referred to simply as "s") of the swelling onset temperature of the powder is preferably 5°C or less, more preferably 4°C or less, even more preferably 3°C or less, even more preferably 2.4°C or less, and particularly preferably 0.85°C or less. The lower limit of s is not particularly limited, but is, for example, 0°C. The standard deviation s of the swelling onset temperature can be calculated as follows:

number

[0038] The ultra-high molecular weight polyethylene powder of this embodiment, having s within the above range, can suppress undissolved polyethylene powder compared to conventional methods, for example, when wet extrusion is performed to produce fibers (e.g., high-strength fibers) or secondary battery separators (e.g., microporous membranes). Furthermore, the ultra-high molecular weight polyethylene powder of this embodiment, having s within the above range, tends to enable the production of higher quality molded articles, such as secondary battery separators with reduced number of defects and thickness variations, and fibers with reduced number of flocs and diameter variations.

[0039] The method for controlling s within the above range is not particularly limited, but examples include a method in which, when producing an ethylene polymer, ethylene and a comonomer are mixed in advance to reduce unevenness in the concentrations of the raw materials, and the mixed gas is introduced into a polymerization vessel, and the polymer powder is dried in a state where it is uniformly spread to a thickness of 5 mm in order to reduce local unevenness in the drying temperature, and / or a method in which the residence time of the polymer powder in a dryer is 5 hours or more in order to dry the polymer powder completely uniformly, and a method in which a plasticizer is added to a polymerization solvent in advance, mixed well, and performed batch polymerization to achieve uniform catalyst activity.

[0040] The ultra-high molecular weight polyethylene powder of this embodiment is D 90 / D 10is preferably 1.2 or more and 4.0 or less, more preferably 1.5 or more and 3.5 or less, and even more preferably 2.0 or more and 3.0 or less. 90 / D 10 When the particle size is within the above range, the apparent density increases, which tends to allow a larger amount of powder to be packed.

[0041] The ultra-high molecular weight polyethylene powder of this embodiment is D 10 is 30 μm or more, and D 90 The ultra-high molecular weight polyethylene powder of the present embodiment preferably has a D 10 When the particle size is 30 μm or more, the powder tends to be easy to handle. 90 When the particle size is 425 μm or less, the processed product tends to have excellent uniformity and appearance. In addition, the ultra-high molecular weight polyethylene powder of this embodiment has a D 10 is more preferably 30 μm or more and 15 μm or less, further preferably 40 μm or more and 140 μm or less, and particularly preferably 50 μm or more and 130 μm or less. 50 is preferably 60 μm or more and 250 μm or less, more preferably 70 μm or more and 240 μm or less, and even more preferably 80 μm or more and 230 μm or less, and D 90 It is more preferable that the thickness is 80 μm or more and 425 μm or less, further more preferable that the thickness is 90 μm or more and 400 μm or less, and particularly preferable that the thickness is 100 μm or more and 350 μm or less.

[0042] [Titanium, aluminum and silicon contents in ultra-high molecular weight polyethylene powder] The ultra-high molecular weight polyethylene powder of this embodiment has a titanium (Ti) content of preferably 5.0 ppm or less, more preferably 0 ppm to 4.0 ppm, and even more preferably 0 ppm to 3.0 ppm. The ultra-high molecular weight polyethylene powder of this embodiment has an aluminum (Al) content of preferably 5.0 ppm or less, more preferably 0 ppm to 4.0 ppm, and even more preferably 0 ppm to 3.0 ppm. The ultra-high molecular weight polyethylene powder of this embodiment has a silicon (Si) content of preferably 100 ppm or less, more preferably 0 ppm to 80 ppm, and even more preferably 0 ppm to 60 ppm. By adjusting the titanium, aluminum, and silicon contents within these ranges, the ultra-high molecular weight polyethylene powder of this embodiment tends to have improved safety when used in, for example, batteries. Generally, a large amount of metal derived from catalyst residue remaining in the ultra-high molecular weight polyethylene powder tends to cause uneven thickness of molded products. The Ti, Al, and Si contents in the ultra-high molecular weight polyethylene powder can be controlled by the productivity of ethylene homopolymer or ethylene-based polymer per unit catalyst. The productivity of ethylene homopolymer or ethylene-based polymer can be controlled by the polymerization temperature, polymerization pressure, and slurry concentration of the reactor during production. In other words, methods for increasing the productivity of the ethylene homopolymer or ethylene-based polymer used in this embodiment are not particularly limited, but include, for example, increasing the polymerization temperature, polymerization pressure, and / or slurry concentration. Other methods for controlling the aluminum content include selecting the type of co-catalyst component or reducing the concentration of the co-catalyst component when polymerizing the ethylene homopolymer or ethylene-based polymer, or washing the ethylene homopolymer or ethylene-based polymer with an acid or alkali. In this embodiment, the contents of Ti, Al, and Si can be measured by the method described in the examples below.

[0043] [Method of manufacturing ultra-high molecular weight polyethylene powder] The method for producing the ultra-high molecular weight polyethylene powder of this embodiment is not particularly limited as long as it is a method that can produce an ultra-high molecular weight polyethylene powder having the above-mentioned properties. Examples include a first production method that includes a step of polymerizing an ethylene polymer by mixing a comonomer into ethylene at a gas phase concentration of 0.01 to 0.05 mol % and drying the polymerized powder at 100°C or higher, and a second production method that includes a polymerization step of polymerizing a polymer in a state in which 30 to 50 mass % of a plasticizer is added to a polymerization solvent. The method for producing ultra-high molecular weight polyethylene powder of this embodiment preferably comprises a removal step of removing the plasticizer from the powder after completion of the polymerization step of the second production method, and a drying step of reducing the catalytic activity during polymerization to 5000 (g-PE / g-catalyst) or less and drying the polymerized powder at 70° C. or less. In addition, the plasticizer is preferably liquid paraffin. (catalyst component) The catalyst component used in the production of the ultra-high molecular weight polyethylene powder according to this embodiment is not particularly limited, but examples thereof include general Ziegler-Natta catalysts and metallocene catalysts. <Ziegler-Natta catalyst> The Ziegler-Natta catalyst is preferably a catalyst comprising a solid catalyst component [A] and an organometallic compound component [B], wherein the solid catalyst component [A] is an olefin polymerization catalyst produced by reacting an organomagnesium compound (A-1) represented by the following formula 1, which is soluble in an inert hydrocarbon solvent, with a titanium compound (A-2) represented by the following formula 2: (A-1):(M 1 ) α (Mg) β (R 2 ) a (R 3 ) b (Y 1 ) c ...Formula 1 (In the formula, M 1 is a metal atom belonging to the group consisting of groups 12, 13, and 14 of the periodic table, and R 2 and R 3 is a hydrocarbon group having 2 to 20 carbon atoms, and Y 1is alkoxy, siloxy, aryloxy, amino, amido, -N=CR 4 , R 5 , -SR 6 (where R 4 , R 5 and R 6 represents a hydrocarbon group having 1 to 20 carbon atoms. When c is 2, Y 1 may be different from each other.) or a β-keto acid residue, and α, β, a, b, and c are real numbers that satisfy the following relationships: 0≦α, 0<β, 0≦a, 0≦b, 0≦c, 0 <a+b、0≦c / (α+β)≦2、nα+2β=a+b+c(ここで、nはM 1 Represents the valence of .))

[0044] (A-2): Ti(OR 7 ) d X 1 (4-d) ...Formula 2 (where d is a real number between 0 and 4, and R 7 is a hydrocarbon group having 1 to 20 carbon atoms, and X 1 is a halogen atom.)

[0045] The inert hydrocarbon solvent used in the reaction of (A-1) and (A-2) is not particularly limited, but specific examples include aliphatic hydrocarbons such as pentane, hexane, and heptane; aromatic hydrocarbons such as benzene and toluene; and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane.

[0046] First, (A-1) will be explained. (A-1) is expressed in the form of an organomagnesium complex compound soluble in an inert hydrocarbon solvent, and includes all dihydrocarbylmagnesium compounds and complexes of these compounds with other metal compounds. The relationship nα+2β=a+b+c between the symbols α, β, a, b, and c indicates the stoichiometry of the valence of the metal atom and the substituent.

[0047] In Equation 1, R 2 and R 3The hydrocarbon group having 2 to 20 carbon atoms is not particularly limited, but specifically includes an alkyl group, a cycloalkyl group, or an aryl group, such as ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, cyclohexyl, and phenyl groups. Among these, alkyl groups are preferred. When α>0, the metal atom M 1 As the metal atom, a metal atom belonging to the group consisting of Groups 12, 13 and 14 of the periodic table can be used, such as zinc, boron, aluminum, etc. Among these, aluminum and zinc are preferred.

[0048] metal atom M 1 The ratio β / α of magnesium to R is not particularly limited, but is preferably 0.1 or more and 30 or less, and more preferably 0.5 or more and 10 or less. When a predetermined organomagnesium compound with α=0 is used, for example, R 2 When R is 1-methylpropyl or the like, it is soluble in an inert hydrocarbon solvent, and such a compound also gives preferable results in this embodiment. 2 , R 3 It is recommended that the applicant fulfill one of the following three groups: (1), (2), or (3).

[0049] Group(1):R 2 , R 3 At least one of R is a secondary or tertiary alkyl group having 4 to 6 carbon atoms, preferably R 2 , R 3 are both alkyl groups having 4 to 6 carbon atoms, and at least one of them is a secondary or tertiary alkyl group. Group(2):R 2 and R 3 and R are alkyl groups having different numbers of carbon atoms, preferably 2 is an alkyl group having 2 or 3 carbon atoms, and R 3 is an alkyl group having 4 or more carbon atoms. Group(3):R 2 , R 3At least one of R is a hydrocarbon group having 6 or more carbon atoms, and preferably R 2 , R 3 The total number of carbon atoms contained in the alkyl group is 12 or more.

[0050] Specific examples of these groups are shown below. Specific examples of the secondary or tertiary alkyl group having 4 to 6 carbon atoms in group (1) include 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, 2-methylbutyl, 2-ethylpropyl, 2,2-dimethylpropyl, 2-methylpentyl, 2-ethylbutyl, 2,2-dimethylbutyl, and 2-methyl-2-ethylpropyl groups. Of these, the 1-methylpropyl group is particularly preferred.

[0051] In addition, in group (2), specific examples of alkyl groups having 2 or 3 carbon atoms include ethyl, 1-methylethyl, and propyl groups. Of these, the ethyl group is particularly preferred. In addition, the alkyl group having 4 or more carbon atoms is not particularly limited, but specific examples include butyl, pentyl, hexyl, heptyl, and octyl groups. Of these, butyl and hexyl groups are particularly preferred.

[0052] Furthermore, the hydrocarbon group having 6 or more carbon atoms in group (3) is not particularly limited, but specific examples include hexyl, heptyl, octyl, nonyl, decyl, phenyl, 2-naphthyl groups, etc. Among the hydrocarbon groups, alkyl groups are preferred, and among the alkyl groups, hexyl and octyl groups are particularly preferred.

[0053] Generally, as the number of carbon atoms contained in the alkyl group increases, the compound tends to be more soluble in an inert hydrocarbon solvent and the viscosity of the solution tends to increase. Therefore, it is preferable to use an alkyl group with a moderate chain length for ease of handling. The organomagnesium compound can be used after being diluted with an inert hydrocarbon solvent, but it can also be used without any problems even if a trace amount of Lewis basic compound such as an ether, ester, or amine is contained or remains in the solution.

[0054] Next, Y 1 In Equation 1, Y 1 is alkoxy, siloxy, aryloxy, amino, amido, -N=CR 4 ,R 5 , -SR 6 (where R 4 , R 5 and R 6 Each independently represents a hydrocarbon group having 2 to 20 carbon atoms, or a β-keto acid residue.

[0055] In Equation 1, R 4 , R 5 and R 6 The hydrocarbon group represented by the formula (I) is preferably an alkyl group or aryl group having 1 to 12 carbon atoms, and particularly preferably an alkyl group or aryl group having 3 to 10 carbon atoms. Examples of the hydrocarbon group include, but are not limited to, methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 1,1-dimethylethyl, pentyl, hexyl, 2-methylpentyl, 2-ethylbutyl, 2-ethylpentyl, 2-ethylhexyl, 2-ethyl-4-methylpentyl, 2-propylheptyl, 2-ethyl-5-methyloctyl, octyl, nonyl, decyl, phenyl, and naphthyl groups. Of these, butyl, 1-methylpropyl, 2-methylpentyl, and 2-ethylhexyl groups are particularly preferred.

[0056] Also, in Equation 1, Y 1is preferably an alkoxy group or a siloxy group. The alkoxy group is not particularly limited, but specifically, for example, methoxy, ethoxy, propoxy, 1-methylethoxy, butoxy, 1-methylpropoxy, 1,1-dimethylethoxy, pentoxy, hexoxy, 2-methylpentoxy, 2-ethylbutoxy, 2-ethylpentoxy, 2-ethylhexoxy, 2-ethyl-4-methylpentoxy, 2-propylheptoxy, 2-ethyl-5-methyloctoxy, octoxy, phenoxy, and naphthoxy groups are preferred. Among these, butoxy, 1-methylpropoxy, 2-methylpentoxy, and 2-ethylhexoxy groups are more preferred. The siloxy group is not particularly limited, but specifically, for example, hydrodimethylsiloxy, ethylhydromethylsiloxy, diethylhydrosiloxy, trimethylsiloxy, ethyldimethylsiloxy, diethylmethylsiloxy, and triethylsiloxy groups are preferred. Of these, hydrodimethylsiloxy, ethylhydromethylsiloxy, diethylhydrosiloxy, and trimethylsiloxy groups are more preferred.

[0057] In this embodiment, the synthesis method of (A-1) is not particularly limited. For example, 2 MgX 1 , and formula R 2 Mg(R 2 has the meaning mentioned above, and X 1 is a halogen.) and an organomagnesium compound of the formula M 1 R 3 n and M 1 R 3 (n-1) H(M 1 , and R 3 has the meaning as above, and n is M 1 ) in an inert hydrocarbon solvent at a temperature of 25°C to 150°C, and if necessary, subsequently reacting with an organometallic compound of formula Y 1 -H(Y 1 has the same meaning as above.) or Y 1Among these, the compound can be synthesized by reacting an organomagnesium compound and / or an organoaluminum compound having a functional group represented by the formula Y 1 When reacting a compound represented by formula Y with a compound represented by formula Y, the order of the reactions is not particularly limited. 1 -H, a method of adding a compound represented by formula Y 1 Either a method of adding the organomagnesium compound to the compound represented by -H or a method of adding both simultaneously can be used.

[0058] In this embodiment, Y relative to all metal atoms in (A-1) 1 The molar composition ratio c / (α+β) of Y is 0≦c / (α+β)≦2, and preferably 0≦c / (α+β)<1. 1 When the molar composition ratio of (A-1) is 2 or less, the reactivity of (A-1) with (A-2) tends to be improved.

[0059] Next, (A-2) will be explained. (A-2) is a titanium compound represented by formula 2. (A-2): Ti(OR 7 ) d X 1 (4-d) ...Formula 2 (where d is a real number between 0 and 4, and R 7 is a hydrocarbon group having 1 to 20 carbon atoms, and X 1 is a halogen atom.)

[0060] In the above formula 2, d is preferably 0 or more and 1 or less, and more preferably 0. In addition, in formula 2, R 7The hydrocarbon group represented by the formula (I) is not particularly limited, but specific examples include aliphatic hydrocarbon groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, 2-ethylhexyl, heptyl, octyl, decyl, and allyl groups; alicyclic hydrocarbon groups such as cyclohexyl, 2-methylcyclohexyl, and cyclopentyl groups; and aromatic hydrocarbon groups such as phenyl and naphthyl groups. Among these, aliphatic hydrocarbon groups are preferred. X 1 Examples of halogens represented by the formula (I) include chlorine, bromine, and iodine. Among these, chlorine is preferred. In this embodiment, (A-2) is particularly preferably titanium tetrachloride. In this embodiment, two or more compounds selected from the above can be used in combination.

[0061] Next, the reaction between (A-1) and (A-2) will be described. The reaction is preferably carried out in an inert hydrocarbon solvent, more preferably in an aliphatic hydrocarbon solvent such as hexane or heptane. The molar ratio of (A-1) to (A-2) in the reaction is not particularly limited, but the molar ratio of Ti atoms contained in (A-2) to Mg atoms contained in (A-1) (Ti / Mg) is preferably 0.1 to 10, more preferably 0.3 to 3. The reaction temperature is not particularly limited, but is preferably carried out in the range of -80°C to 150°C, more preferably -40°C to 100°C. The order of addition of (A-1) and (A-2) is not particularly limited, and any of the following methods is possible: adding (A-2) after (A-1), adding (A-2) after (A-1), or adding (A-1) and (A-2) simultaneously. However, the method of adding (A-1) and (A-2) simultaneously is preferred. In this embodiment, the solid catalyst component [A] obtained by the above reaction is used as a slurry solution using an inert hydrocarbon solvent.

[0062] Another example of the Ziegler-Natta catalyst component used in this embodiment is preferably an olefin polymerization catalyst comprising a solid catalyst component [C] and an organometallic compound component [B], wherein the solid catalyst component [C] is produced by supporting an organomagnesium compound (C-4) soluble in an inert hydrocarbon solvent, represented by formula 5, and a titanium compound (C-5) represented by formula 6, on a support (C-3) prepared by reacting an organomagnesium compound (C-1) soluble in an inert hydrocarbon solvent, represented by formula 3, with a chlorinating agent (C-2) represented by formula 4.

[0063] (C-1):(M 2 ) γ (Mg) δ (R 8 ) e (R 9 ) f (OR 10 ) g ...Formula 3 (In the formula, M 2 is a metal atom belonging to the group consisting of groups 12, 13, and 14 of the periodic table, and R 8 , R 9 and R 10 are hydrocarbon groups having 2 to 20 carbon atoms, and γ, δ, e, f, and g are real numbers that satisfy the following relationships: 0≦γ, 0<δ, 0≦e, 0≦f, 0≦g, 0 <e+f、0≦g / (γ+δ)≦2、kγ+2δ=e+f+g(ここで、kはM 2 Represents the valence of .))

[0064] (C-2):H h SiCl i R 11 (4-(h+i)) ...Formula 4 (In the formula, R 11 is a hydrocarbon group having 1 to 12 carbon atoms, and h and i are real numbers that satisfy the following relationship: 0 <h、0<i、0<h+i≦4)

[0065] (C-4):(M 1 ) α (Mg) β (R 2 ) a (R 3 )b Y 1 c ...Formula 5 (In the formula, M 1 is a metal atom belonging to the group consisting of groups 12, 13, and 14 of the periodic table, and R 2 and R 3 is a hydrocarbon group having 2 to 20 carbon atoms, and Y 1 is alkoxy, siloxy, aryloxy, amino, amido, -N=CR 4 ,R 5 , -SR 6 (where R 4 , R 5 and R 6 represents a hydrocarbon group having 1 to 20 carbon atoms. When c is 2, Y 1 may be different from each other.) or a β-keto acid residue, and α, β, a, b, and c are real numbers that satisfy the following relationships: 0≦α, 0<β, 0≦a, 0≦b, 0≦c, 0 <a+b、0≦c / (α+β)≦2、nα+2β=a+b+c(ここで、nはM 1 Represents the valence of .))

[0066] (C-5): Ti(OR 7 ) d X 1 (4-d) ...Formula 6 (where d is a real number between 0 and 4, and R 7 is a hydrocarbon group having 1 to 20 carbon atoms, and X 1 is a halogen atom.)

[0067] First, (C-1) will be explained. (C-1) is shown in the form of an organomagnesium complex compound soluble in an inert hydrocarbon solvent, but it encompasses all dihydrocarbylmagnesium compounds and complexes of these compounds with other metal compounds. The relationship kγ+2δ=e+f+g between the symbols γ, δ, e, f, and g in formula 3 indicates the stoichiometry of the valence of the metal atom and the substituent.

[0068] In the above formula, R 8 Or R 9The hydrocarbon group represented by is not particularly limited, but specifically, it is an alkyl group, a cycloalkyl group, or an aryl group, and examples thereof include methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, cyclohexyl, and phenyl groups. Among these, R 8 and R 9 are alkyl groups. When α>0, the metal atom M 2 As the metal atom, a metal atom belonging to the group consisting of Groups 12, 13 and 14 of the periodic table can be used, such as zinc, boron, aluminum, etc. Of these, aluminum and zinc are particularly preferred.

[0069] metal atom M 2 The ratio δ / γ of magnesium to R is not particularly limited, but is preferably 0.1 or more and 30 or less, and more preferably 0.5 or more and 10 or less. When a predetermined organomagnesium compound with γ=0 is used, for example, R 8 When R is 1-methylpropyl or the like, it is soluble in an inert hydrocarbon solvent, and such a compound also gives preferable results in this embodiment. 8 , R 9 It is recommended that the patient be in one of the following three groups: (1), (2), or (3).

[0070] Group(1):R 8 , R 9 At least one of R is a secondary or tertiary alkyl group having 4 to 6 carbon atoms, and preferably R 8 , R 9 Both of these have 4 to 6 carbon atoms, and at least one of them is a secondary or tertiary alkyl group. Group(2):R 8 and R 9 and R are alkyl groups having different carbon numbers, preferably 8 is an alkyl group having 2 or 3 carbon atoms, and R 9 is an alkyl group having 4 or more carbon atoms. Group(3):R 8 , R 9At least one of R is a hydrocarbon group having 6 or more carbon atoms, and preferably R 8 , R 9 The total number of carbon atoms contained in the alkyl group is 12 or more.

[0071] Specific examples of these groups are shown below. Specific examples of the secondary or tertiary alkyl group having 4 to 6 carbon atoms in group (1) include 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, 2-methylbutyl, 2-ethylpropyl, 2,2-dimethylpropyl, 2-methylpentyl, 2-ethylbutyl, 2,2-dimethylbutyl, and 2-methyl-2-ethylpropyl groups. Of these, the 1-methylpropyl group is particularly preferred.

[0072] In addition, in group (2), examples of alkyl groups having 2 or 3 carbon atoms include ethyl, 1-methylethyl, and propyl groups. Of these, the ethyl group is particularly preferred. Furthermore, examples of alkyl groups having 4 or more carbon atoms include, but are not particularly limited to, butyl, pentyl, hexyl, heptyl, and octyl groups. Of these, butyl and hexyl groups are particularly preferred.

[0073] Furthermore, the hydrocarbon group having 6 or more carbon atoms in group (3) is not particularly limited, but specific examples include hexyl, heptyl, octyl, nonyl, decyl, phenyl, 2-naphthyl groups, etc. Among the hydrocarbon groups, alkyl groups are preferred, and among the alkyl groups, hexyl and octyl groups are particularly preferred.

[0074] Generally, as the number of carbon atoms contained in the alkyl group increases, the compound tends to be more soluble in an inert hydrocarbon solvent, and the viscosity of the solution tends to increase. Therefore, it is preferable to use an alkyl group with a moderate chain length for ease of handling. The organomagnesium compound is used as an inert hydrocarbon solution, but it can be used without any problems even if a trace amount of Lewis basic compounds such as ethers, esters, and amines is contained or remains in the solution.

[0075] Next, the alkoxy group (OR 10 ) will be explained. 10 The hydrocarbon group represented by R is preferably an alkyl group or aryl group having 1 to 12 carbon atoms, and particularly preferably an alkyl group or aryl group having 3 to 10 carbon atoms. 10 Although not particularly limited, specific examples include methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 1,1-dimethylethyl, pentyl, hexyl, 2-methylpentyl, 2-ethylbutyl, 2-ethylpentyl, 2-ethylhexyl, 2-ethyl-4-methylpentyl, 2-propylheptyl, 2-ethyl-5-methyloctyl, octyl, nonyl, decyl, phenyl, naphthyl groups, etc. Among these, butyl, 1-methylpropyl, 2-methylpentyl, and 2-ethylhexyl groups are particularly preferred.

[0076] In this embodiment, the synthesis method of (C-1) is not particularly limited, but a compound represented by the formula R 8 MgX 1 and formula R 8 Mg(R 8 has the meaning mentioned above, and X 1 is a halogen atom; and an organomagnesium compound of the formula M 2 R 9 k and formula M 2 R 9 (k-1) H(M 2 , R 9 and k has the same meaning as above) in an inert hydrocarbon solvent at a temperature of 25°C to 150°C, and if necessary, subsequently reacting with an organometallic compound belonging to the group consisting of R 9 (R 9 has the same meaning as above.) R soluble in an alcohol or an inert hydrocarbon solvent having a hydrocarbon group represented by 9 In another preferred method, the compound is reacted with an alkoxy magnesium compound having a hydrocarbon group represented by the following formula: and / or an alkoxy aluminum compound.

[0077] Among these, when an organomagnesium compound soluble in an inert hydrocarbon solvent is reacted with an alcohol, the order of the reaction is not particularly limited, and any of a method of adding the alcohol to the organomagnesium compound, a method of adding the organomagnesium compound to the alcohol, or a method of adding both simultaneously can be used. In this embodiment, the reaction ratio of the organomagnesium compound soluble in an inert hydrocarbon solvent and the alcohol is not particularly limited, but the molar composition ratio g / (γ+δ) of alkoxy groups to all metal atoms in the alkoxy group-containing organomagnesium compound obtained as a result of the reaction is preferably 0≦g / (γ+δ)≦2, and 0≦g / (γ+δ)<1.

[0078] Next, (C-2) will be explained. (C-2) is a silicon chloride compound represented by formula 4, which has at least one Si—H bond.

[0079] (C-2):H h SiCl i R 11 (4-(h+i)) ...Formula 4 (In the formula, R 11 is a hydrocarbon group having 1 to 12 carbon atoms, and h and i are real numbers that satisfy the following relationship: 0 <h、0<i、0<h+i≦4)

[0080] In Equation 4, R 11 The hydrocarbon group represented by the formula (I) is not particularly limited, but specific examples include aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups, such as methyl, ethyl, propyl, 1-methylethyl, butyl, pentyl, hexyl, octyl, decyl, cyclohexyl, and phenyl groups. Among these, alkyl groups having 1 to 10 carbon atoms are preferred, and alkyl groups having 1 to 3 carbon atoms, such as methyl, ethyl, propyl, and 1-methylethyl groups, are more preferred. Furthermore, h and i are numbers greater than 0 that satisfy the relationship h+i≦4, and it is preferred that i be 2 to 3.

[0081] These compounds are not particularly limited, but specific examples include HSiCl3, HSiCl2CH3, HSiCl2C2H5, HSiCl2(C3H7), HSiCl2(2-C3H7), HSiCl2(C4H9), HSiCl2(C6H5), HSiCl2(4-Cl-C6H4), HSiCl2(CH=CH2), HSiCl2(CH2C6H5), HSiCl2(1-C 10 Examples of silicon chloride compounds include HSiCl(CHCH=CH), HSiCl(CH), HSiCl(CH), HSiCl(CH), HSiCl(CH), HSiCl(CH), HSiCl(CH), HSiCl(CH)(2-CH), HSiCl(CH)(CH), HSiCl(CH). Silicon chloride compounds that are used include these compounds or mixtures of two or more selected from these compounds. Among these, HSiCl, HSiClCH, HSiCl(CH), and HSiCl(CH) are preferred, with HSiCl and HSiClCH being more preferred.

[0082] Next, the reaction between (C-1) and (C-2) will be described. During the reaction, (C-2) is preferably diluted with an inert hydrocarbon solvent, such as a chlorinated hydrocarbon (e.g., 1,2-dichloroethane, o-dichlorobenzene, or dichloromethane); an ether-based solvent (e.g., diethyl ether or tetrahydrofuran); or a mixture thereof. Among these, an inert hydrocarbon solvent is more preferred in terms of catalyst performance. The reaction ratio of (C-1) to (C-2) is not particularly limited, but the ratio of silicon atoms contained in (C-2) to 1 mole of magnesium atoms contained in (C-1) is preferably 0.01 mol to 100 mol, more preferably 0.1 mol to 10 mol.

[0083] The reaction method between (C-1) and (C-2) is not particularly limited, and any of the following methods can be used: a simultaneous addition method in which (C-1) and (C-2) are simultaneously introduced into a reactor and reacted; a method in which (C-2) is previously charged into a reactor and then (C-1) is introduced into the reactor; or a method in which (C-1) is previously charged into a reactor and then (C-2) is introduced into the reactor. Among these, a method in which (C-2) is previously charged into a reactor and then (C-1) is introduced into the reactor is preferred. The support (C-3) obtained by the above reaction is preferably separated by filtration or decantation, and then thoroughly washed with an inert hydrocarbon solvent to remove unreacted materials or by-products.

[0084] The reaction temperature between (C-1) and (C-2) is not particularly limited, but is preferably 25°C or higher and 150°C or lower, more preferably 30°C or higher and 120°C or lower, and even more preferably 40°C or higher and 100°C or lower. In a simultaneous addition method in which (C-1) and (C-2) are simultaneously introduced into a reactor and reacted, it is preferable to adjust the temperature of the reactor to a predetermined temperature in advance, and then adjust the temperature inside the reactor to a predetermined temperature while performing the simultaneous addition, thereby adjusting the reaction temperature to a predetermined temperature. In a method in which (C-2) is previously charged into a reactor and then (C-1) is introduced into the reactor, it is preferable to adjust the temperature of a reactor into which the silicon chloride compound has been charged to a predetermined temperature, and then adjust the temperature inside the reactor to a predetermined temperature while introducing the organomagnesium compound into the reactor, thereby adjusting the reaction temperature to a predetermined temperature. In the method of charging (C-1) into a reactor in advance and then introducing (C-2) into the reactor, it is preferable to adjust the temperature of the reactor into which (C-1) has been charged to a predetermined temperature, and then adjust the temperature inside the reactor to a predetermined temperature while introducing (C-2) into the reactor, thereby adjusting the reaction temperature to a predetermined temperature.

[0085] Next, the organomagnesium compound (C-4) will be explained. As (C-4), the compound represented by the above formula 5 (C-4) is preferred.

[0086] (C-4):(M 1 ) α(Mg) β (R 2 ) a (R 3 ) b Y 1 c ...Formula 5 (In the formula, M 1 is a metal atom belonging to the group consisting of groups 12, 13, and 14 of the periodic table, and R 2 and R 3 is a hydrocarbon group having 2 to 20 carbon atoms, and Y 1 is alkoxy, siloxy, aryloxy, amino, amido, -N=CR 4 ,R 5 , -SR 6 (where R 4 , R 5 and R 6 represents a hydrocarbon group having 1 to 20 carbon atoms. When c is 2, Y 1 may be different from each other.) or a β-keto acid residue, and α, β, a, b, and c are real numbers that satisfy the following relationships: 0≦α, 0<β, 0≦a, 0≦b, 0 <a+b、0≦c / (α+β)≦2、nα+2β=a+b+c(ここで、nはM 1 Represents the valence of .))

[0087] The amount of (C-4) used is preferably 0.1 or more and 10 or less, more preferably 0.5 or more and 5 or less, in terms of the molar ratio of magnesium atoms contained in (C-4) to titanium atoms contained in (C-5).

[0088] The temperature for the reaction of (C-4) and (C-5) is not particularly limited, but is preferably in the range of -80°C or higher and 150°C or lower, and more preferably in the range of -40°C or higher and 100°C or lower.

[0089] The concentration of (C-4) when used is not particularly limited, but is preferably 0.1 mol / L or more and 2 mol / L or less, and more preferably 0.5 mol / L or more and 1.5 mol / L or less, based on the titanium atoms contained in (C-4). Note that an inert hydrocarbon solvent is preferably used to dilute (C-4).

[0090] The order of addition of (C-4) and (C-5) to (C-3) is not particularly limited, and any of the following methods is possible: adding (C-4) followed by (C-5), adding (C-5) followed by (C-4), or adding (C-4) and (C-5) simultaneously. Among these, the method of adding (C-4) and (C-5) simultaneously is preferred. The reaction between (C-4) and (C-5) is carried out in an inert hydrocarbon solvent, preferably an aliphatic hydrocarbon solvent such as hexane or heptane. The catalyst thus obtained is used as a slurry solution using an inert hydrocarbon solvent.

[0091] Next, (C-5) will be explained. In this embodiment, (C-5) is a titanium compound represented by the above formula 6.

[0092] (C-5): Ti(OR 7 ) d X 1 (4-d) ...Formula 6 (where d is a real number between 0 and 4, and R 7 is a hydrocarbon group having 1 to 20 carbon atoms, and X 1 is a halogen atom.)

[0093] In Equation 6, R 7 The hydrocarbon group represented by the formula (I) is not particularly limited, but specific examples include aliphatic hydrocarbon groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, 2-ethylhexyl, heptyl, octyl, decyl, and allyl groups; alicyclic hydrocarbon groups such as cyclohexyl, 2-methylcyclohexyl, and cyclopentyl groups; and aromatic hydrocarbon groups such as phenyl and naphthyl groups. Among these, aliphatic hydrocarbon groups are preferred. X 1 The halogen represented by the formula (C-5) is not particularly limited, but specific examples include chlorine, bromine, and iodine. Among these, chlorine is preferred. The (C-5) selected from the above may be used alone or in combination of two or more.

[0094] The amount of (C-5) used is not particularly limited, but is preferably 0.01 or more and 20 or less, particularly preferably 0.05 or more and 10 or less, in terms of molar ratio to the magnesium atoms contained in the carrier (C-3).

[0095] The reaction temperature of (C-5) is not particularly limited, but is preferably in the range of -80°C or higher and 150°C or lower, and more preferably in the range of -40°C or higher and 100°C or lower. In this embodiment, the method for supporting (C-5) on (C-3) is not particularly limited. A method of reacting an excess of (C-5) with (C-3) or a method of efficiently supporting (C-5) by using a third component may be used, but a method of supporting (C-5) by reacting (C-5) with an organomagnesium compound (C-4) is preferred.

[0096] Next, the organometallic compound component [B] used in this embodiment will be described. The solid catalyst component used in this embodiment becomes a highly active polymerization catalyst when combined with the organometallic compound component [B]. The organometallic compound component [B] is sometimes called a "co-catalyst." The organometallic compound component [B] is preferably a compound containing a metal belonging to the group consisting of Groups 1, 2, 12, and 13 of the periodic table, and is particularly preferably an organoaluminum compound and / or an organomagnesium compound.

[0097] As the organoaluminum compound, it is preferable to use a compound represented by the following formula 7, either alone or in combination.

[0098] AlR 12 j Z 1 (3-j) ...Formula 7 (In the formula, R 12 is a hydrocarbon group having 1 to 20 carbon atoms, Z 1 is a radical belonging to the group consisting of hydrogen, halogen, alkoxy, aryloxy, and siloxy groups, and j is a number between 2 and 3.

[0099] In the above formula 7, R 12The hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) is not particularly limited, but specifically includes aliphatic hydrocarbons, aromatic hydrocarbons, and alicyclic hydrocarbons. For example, trialkylaluminums such as trimethylaluminum, triethylaluminum, tripropylaluminum, tributylaluminum, tri(2-methylpropyl)aluminum (or triisobutylaluminum), tripentylaluminum, tri(3-methylbutyl)aluminum, trihexylaluminum, trioctylaluminum, and tridecylaluminum; aluminum halide compounds such as diethylaluminum chloride, ethylaluminum dichloride, bis(2-methylpropyl)aluminum chloride, ethylaluminum sesquichloride, and diethylaluminum bromide; alkoxyaluminum compounds such as diethylaluminum ethoxide and bis(2-methylpropyl)aluminum butoxide; siloxyaluminum compounds such as dimethylhydrosiloxyaluminum dimethyl, ethylmethylhydrosiloxyaluminum diethyl, and ethyldimethylsiloxyaluminum diethyl; and mixtures thereof are preferred. Among these, trialkylaluminum compounds are particularly preferred.

[0100] As the organomagnesium compound, an organomagnesium compound soluble in an inert hydrocarbon solvent represented by the above formula 3 is preferred.

[0101] (M 2 ) γ (Mg) δ (R 8 ) e (R 9 ) f (OR 10 ) g ...Formula 3 (In the formula, M 2 is a metal atom belonging to the group consisting of groups 12, 13, and 14 of the periodic table, and R 8 , R 9 and R 10are hydrocarbon groups having 2 to 20 carbon atoms, and γ, δ, e, f, and g are real numbers that satisfy the following relationships: 0≦γ, 0<δ, 0≦e, 0≦f, 0≦g, 0 <e+f、0≦g / (γ+δ)≦2、kγ+2δ=e+f+g(ここで、kはM 2 Represents the valence of .))

[0102] This organomagnesium compound is shown in the form of an organomagnesium complex compound soluble in an inert hydrocarbon solvent, but it also includes dialkylmagnesium compounds and complexes of these compounds with other metal compounds. 2 , R 8 , R 9 , OR 10 As already mentioned, it is preferable that the organomagnesium compound has high solubility in an inert hydrocarbon solvent, and therefore, δ / γ is preferably in the range of 0.5 to 10. 2 More preferred are compounds in which is aluminum. The combination ratio of the solid catalyst component and the organometallic compound component [B] is not particularly limited, but it is preferable that the organometallic compound component [B] is 1 mmol or more and 3,000 mmol or less per 1 g of the solid catalyst component.

[0103] <Metallocene catalyst> In an example using a metallocene catalyst, a general transition metal compound is used. The method for producing the metallocene catalyst is not particularly limited, but an example thereof is the production method described in Japanese Patent No. 4868853. Such a metallocene catalyst is composed of two catalytic components: a) a transition metal compound having a cyclic η-bonding anionic ligand, and b) an activator capable of reacting with the transition metal compound to form a complex that exhibits catalytic activity.

[0104] The transition metal compound having a cyclic η-bonding anionic ligand used in this embodiment can be represented by, for example, the following formula 8. L 1 j W k M 3 X 2p X 3 q ...Formula 8

[0105] In Equation 8, L 1 each independently represent an η-bonding cyclic anionic ligand selected from the group consisting of a cyclopentadienyl group, an indenyl group, a tetrahydroindenyl group, a fluorenyl group, a tetrahydrofluorenyl group, and an octahydrofluorenyl group, and the ligand optionally has 1 to 8 substituents, each of which is independently a substituent having up to 20 non-hydrogen atoms selected from the group consisting of a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, a halogen-substituted hydrocarbon group having 1 to 12 carbon atoms, an aminohydrocarbyl group having 1 to 12 carbon atoms, a hydrocarbyloxy group having 1 to 12 carbon atoms, a dihydrocarbylamino group having 1 to 12 carbon atoms, a hydrocarbylphosphino group having 1 to 12 carbon atoms, a silyl group, an aminosilyl group, a hydrocarbyloxysilyl group having 1 to 12 carbon atoms, and a halosilyl group.

[0106] In Equation 8, M 3 is a transition metal selected from the group of transition metals belonging to Group 4 of the periodic table having a formal oxidation number of +2, +3 or +4, and is a metal having at least one ligand L 1 η 5 Represents a bonded transition metal.

[0107] In Formula 8, W is a divalent substituent having up to 50 non-hydrogen atoms, and L 1 and M 3 Each bond has a valence of 1, resulting in L 1 and M 3 represents a divalent substituent that cooperates with X to form a metallocycle; 2 are each independently a monovalent anionic σ-bonded ligand, M 3 a divalent anionic σ-bonded ligand that is divalently bonded to L, and 1 and M 3 and a divalent anionic σ-bonded ligand having up to 60 non-hydrogen atoms, the divalent anionic σ-bonded ligand being bonded to each of the anionic σ-bonded ligands with a valence of 1.

[0108] In Equation 8, X 2 each independently represents a neutral Lewis base coordinating compound having up to 40 non-hydrogen atoms; X 3 represents a neutral Lewis base coordinating compound.

[0109] j is 1 or 2, provided that when j is 2, two ligands L 1 are bonded to each other via a divalent group having up to 20 non-hydrogen atoms, and the divalent group is a group selected from the group consisting of hydrocarbadiyl groups having 1 to 20 carbon atoms, halohydrocarbadiyl groups having 1 to 12 carbon atoms, hydrocarbyleneoxy groups having 1 to 12 carbon atoms, hydrocarbyleneamino groups having 1 to 12 carbon atoms, silanediyl groups, halosilanediyl groups, and silyleneamino groups.

[0110] k is 0 or 1, and p is 0, 1, or 2, provided that X 2 is a monovalent anionic σ-bonded ligand, or L 1 and M 3 If p is a divalent anionic σ-bonded ligand bound to M 3 is an integer that is one or more smaller than the formal oxidation number of X 2 M 3 If the ligand is a divalent anionic σ-bonded ligand bound only to M, then p is M 3 is an integer that is (j+1) or more less than the formal oxidation number of , and q is 0, 1, or 2.

[0111] Ligand X in the compound of formula 8 above 2 Examples of the alkyl group include halides, hydrocarbon groups having 1 to 60 carbon atoms, hydrocarbyloxy groups having 1 to 60 carbon atoms, hydrocarbylamide groups having 1 to 60 carbon atoms, hydrocarbyl phosphate groups having 1 to 60 carbon atoms, hydrocarbyl sulfide groups having 1 to 60 carbon atoms, silyl groups, and composite groups thereof.

[0112] The neutral Lewis base coordinating compound X in the compound of formula 8 3Examples of the alkyl group include phosphines, ethers, amines, olefins having 2 to 40 carbon atoms, dienes having 1 to 40 carbon atoms, and divalent groups derived from these compounds.

[0113] In this embodiment, the transition metal compound having a cyclic η-bonding anionic ligand is preferably a transition metal compound represented by the above formula 1 (where j = 1). A preferred example of the compound represented by the above formula 1 (where j = 1) is a compound represented by the following formula 9.

[0114] [ka]

[0115] In Equation 9, M 4 represents a transition metal selected from the group consisting of titanium, zirconium, nickel, and hafnium, and has a formal oxidation state of +2, +3, or +4; R 13 each independently represents a substituent having up to 20 non-hydrogen atoms selected from the group consisting of a hydrogen atom, a hydrocarbon group having 1 to 8 carbon atoms, a silyl group, a germyl group, a cyano group, a halogen atom, and a composite group thereof, provided that the substituent R 13 is a hydrocarbon group having 1 to 8 carbon atoms, a silyl group, or a germyl group, two adjacent substituents R 13 are bonded to each other to form a divalent group, whereby the two adjacent substituents R 13 can cooperate with the bonds between the two carbon atoms of the cyclopentadienyl ring to form a ring.

[0116] In Equation 9, X 4each independently represents a substituent having up to 20 non-hydrogen atoms selected from the group consisting of a halide, a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbyloxy group having 1 to 18 carbon atoms, a hydrocarbylamino group having 1 to 18 carbon atoms, a silyl group, a hydrocarbylamide group having 1 to 18 carbon atoms, a hydrocarbyl phosphate group having 1 to 18 carbon atoms, a hydrocarbyl sulfide group having 1 to 18 carbon atoms, and a composite group thereof, provided that in some cases two substituents X 4 can cooperate to form a neutral conjugated diene or divalent group having 4 to 30 carbon atoms.

[0117] In Equation 9, Y 2 -O-, -S-, -NR * -or-PR * -, where R * represents a hydrogen atom, a hydrocarbon group having 1 to 12 carbon atoms, a hydrocarbyloxy group having 1 to 8 carbon atoms, a silyl group, a halogenated alkyl group having 1 to 8 carbon atoms, a halogenated aryl group having 6 to 20 carbon atoms, or a composite group thereof.

[0118] In Equation 9, Z 2 is SiR * 2. CR * 2. SiR * 2SiR * 2. CR * 2CR *2 , C.R. * =CR * , C.R. * 2SiR * 2 or GeR * 2, where R * is as defined above and n is 1, 2 or 3.

[0119] Examples of the transition metal compound having a cyclic η-bonding anion ligand used in this embodiment include the compounds shown below. The zirconium-based compound is not particularly limited, but specific examples include bis(methylcyclopentadienyl)zirconium dimethyl, bis(n-butylcyclopentadienyl)zirconium dimethyl, bis(indenyl)zirconium dimethyl, bis(1,3-dimethylcyclopentadienyl)zirconium dimethyl, (pentamethylcyclopentadienyl)(cyclopentadienyl)zirconium dimethyl, bis(cyclopentadienyl)zirconium dimethyl, bis(pentamethylcyclopentadienyl)zirconium dimethyl, bis(fluorenyl)zirconium dimethyl, ethylenebis(indenyl)zirconium dimethyl, ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dimethyl, ethylenebis(4-methyl-1-indenyl)zirconium dimethyl, and ethylenebis(5-methyl-1-indenyl). ) zirconium dimethyl, ethylene bis(6-methyl-1-indenyl) zirconium dimethyl, ethylene bis(7-methyl-1-indenyl) zirconium dimethyl, ethylene bis(5-methoxy-1-indenyl) zirconium dimethyl, ethylene bis(2,3-dimethyl-1-indenyl) zirconium dimethyl, ethylene bis(4,7-dimethyl-1-indenyl) zirconium dimethyl, ethylene bis-(4,7-dimethoxy-1-indenyl) zirconium dimethyl, methylene bis(cyclopentadienyl) zirconium dimethyl, isopropylidene(cyclopentadienyl) zirconium dimethyl, isopropylidene(cyclopentadienyl-fluorenyl) zirconium dimethyl, silylene bis(cyclopentadienyl) zirconium dimethyl, dimethylsilylene(cyclopentadienyl) zirconium dimethyl, and the like.

[0120] The titanium-based compound is not particularly limited, but specific examples thereof include [(Nt-butylamido)(tetramethyl-η 5 -cyclopentadienyl)-1,2-ethanediyl]titanium dimethyl, [(Nt-butylamido)(tetramethyl-η 5-cyclopentadienyl)dimethylsilane]titanium dimethyl, [(N-methylamido)(tetramethyl-η 5 -cyclopentadienyl)dimethylsilane]titanium dimethyl, [(N-phenylamido)(tetramethyl-η 5 -cyclopentadienyl)dimethylsilane]titanium dimethyl, [(N-benzylamido)(tetramethyl-η 5 -cyclopentadienyl)dimethylsilane]titanium dimethyl, [(Nt-butylamido)(η 5 -cyclopentadienyl)-1,2-ethanediyl]titanium dimethyl, [(Nt-butylamido)(η 5 -cyclopentadienyl)dimethylsilane]titanium dimethyl, [(N-methylamido)(η 5 -cyclopentadienyl)-1,2-ethanediyl]titanium dimethyl, [(N-methylamido)(η 5 -cyclopentadienyl)dimethylsilane]titanium dimethyl, [(Nt-butylamido)(η 5 -indenyl)dimethylsilane]titanium dimethyl, [(N-benzylamide)(η 5 -indenyl)dimethylsilane]titanium dimethyl, and the like.

[0121] The nickel-based compound is not particularly limited, but specific examples thereof include dibromobistriphenylphosphine nickel, dichlorobistriphenylphosphine nickel, dibromodiacetonitrile nickel, dibromodibenzonitrile nickel, dibromo(1,2-bisdiphenylphosphinoethane)nickel, dibromo(1,3-bisdiphenylphosphinopropane)nickel, dibromo(1,1'-diphenylbisphosphinoferrocene)nickel, dimethylbisdiphenylphosphine nickel, and dimethyl(1,2-bisdiphenylphosphinoethane)nickel. Examples of such an ion exchange catalyst include nickel, methyl(1,2-bisdiphenylphosphinoethane)nickel tetrafluoroborate, (2-diphenylphosphino-1-phenylethyleneoxy)phenylpyridine nickel, dichlorobistriphenylphosphine palladium, dichlorodibenzonitrile palladium, dichlorodiacetonitrile palladium, dichloro(1,2-bisdiphenylphosphinoethane)palladium, bistriphenylphosphine palladium bistetrafluoroborate, and bis(2,2'-bipyridine)methyliron tetrafluoroborate etherate.

[0122] The hafnium-based compound is not particularly limited, but specific examples thereof include [(Nt-butylamido)(tetramethyl-η5-cyclopentadienyl)-1,2-ethanediyl]hafnium dimethyl, [(Nt-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethylsilane]hafnium dimethyl, [(N-methylamido)(tetramethyl-η5-cyclopentadienyl)dimethylsilane]hafnium dimethyl, [(N-phenylamido)(tetramethyl-η5-cyclopentadienyl)dimethylsilane]hafnium dimethyl, [(N-benzylamido)(tetramethyl-η5-cyclopentadienyl)dimethylsilane [(N-butylamido)(η5-cyclopentadienyl)-1,2-ethanediyl]hafnium dimethyl, [(N-butylamido)(η5-cyclopentadienyl)dimethylsilane]hafnium dimethyl, [(N-methylamido)(η5-cyclopentadienyl)-1,2-ethanediyl]hafnium dimethyl, [(N-methylamido)(η5-cyclopentadienyl)dimethylsilane]hafnium dimethyl, [(N-butylamido)(η5-indenyl)dimethylsilane]hafnium dimethyl, [(N-benzylamido)(η5-indenyl)dimethylsilane]hafnium dimethyl, and the like.

[0123] Specific examples of transition metal compounds having a cyclic η-bonding anionic ligand used in this embodiment further include the "dimethyl" portion of the name of each of the zirconium-based compounds and titanium-based compounds listed above (this appears immediately after the "zirconium" or "titanium" portion at the end of the name of each compound, and is the same as X in Formula 2 above). 4 (the name corresponding to the part of the formula) can be used, for example, to refer to "dichloro", "dibromide", "diiodide", "diethyl", "dibutyl", "diphenyl", "dibenzyl", "2-(N,N-dimethylamino)benzyl", "2-butene-1,4-diyl", "s-trans-η4-1,4-diphenyl-1,3-butadiene", "s-trans-η 4 -3-methyl-1,3-pentadiene", "s-trans-η 4-1,4-dibenzyl-1,3-butadiene", "s-trans-η 4 -2,4-hexadiene", "s-trans-η 4 -1,3-pentadiene", "s-trans-η 4 -1,4-ditolyl-1,3-butadiene", "s-trans-η 4 -1,4-bis(trimethylsilyl)-1,3-butadiene," "s-cis-η 4 -1,4-diphenyl-1,3-butadiene", "s-cis-η 4 -3-methyl-1,3-pentadiene", "s-cis-η 4 -1,4-dibenzyl-1,3-butadiene", "s-cis-η 4 -2,4-hexadiene", "s-cis-η 4 -1,3-pentadiene", "s-cis-η 4 -1,4-ditolyl-1,3-butadiene", "s-cis-η 4 Also included are compounds with names that can be replaced with any other name, such as "-1,4-bis(trimethylsilyl)-1,3-butadiene."

[0124] The transition metal compounds having a cyclic η-bonding anionic ligand used in this embodiment can be synthesized by a generally known method. In this embodiment, these transition metal compounds may be used alone or in combination.

[0125] Next, the activator b) capable of reacting with the transition metal compound to form a complex that exhibits catalytic activity (hereinafter, also simply referred to as "activator") used in this embodiment will be described. An example of the activator used in this embodiment is a compound defined by the following formula 10. [L 2 -H] d+ [M 5 m Q p ] d- ...Formula 10 (In the formula, [L 2 -H] d+ represents a proton-donating Bronsted acid, where L 2represents a neutral Lewis base, d is an integer of 1 to 7; [M 5 m Q p ] d- represents a compatible non-coordinating anion, where M 5 represents a metal or metalloid belonging to any of Groups 5 to 15 of the periodic table, and each Q is independently selected from the group consisting of hydride, halide, dihydrocarbylamide group having 2 to 20 carbon atoms, hydrocarbyloxy group having 1 to 30 carbon atoms, hydrocarbon group having 1 to 30 carbon atoms, and substituted hydrocarbon group having 1 to 40 carbon atoms, wherein the number of Q that is a halide is 1 or less, m is an integer of 1 to 7, p is an integer of 2 to 14, d is as defined above, and pm=d.

[0126] The non-coordinating anion is not particularly limited, but specific examples thereof include tetrakisphenylborate, tri(p-tolyl)(phenyl)borate, tris(pentafluorophenyl)(phenyl)borate, tris(2,4-dimethylphenyl)(hydrophenyl)borate, tris(3,5-dimethylphenyl)(phenyl)borate, tris(3,5-di-trifluorimethylphenyl)(phenyl)borate, tris(pentafluorophenyl)(cyclohexyl)borate, tris(pentafluorophenyl)(naphthyl)borate, tetrakis(pentafluorophenyl)borate, triphenyl(hydroxyphenyl)borate, diphenyl-di(hydroxyphenyl)borate, triphenyl(2,4-dihydroxyphenyl)borate, tri(p-trihydroxyphenyl)borate, tris(pentafluorophenyl)(hydroxyphenyl)borate, tris(pentafluorophenyl)(hydroxyphenyl)borate, tris(2,4-dimethylphenyl)(hydroxyphenyl)borate, tris(3,5-dimethylphenyl)(hydroxyphenyl)borate, tris(3,5-di-trifluorimethylphenyl)(hydroxyphenyl)borate, tris(pentafluorophenyl)(2-hydroxyethyl)borate, tris(pentafluorophenyl)(4-hydroxybutyl)borate, tris(pentafluorophenyl)(4-hydroxycyclohexyl)borate, tris(pentafluorophenyl)(4-(4'-hydroxyphenyl)phenyl)borate, tris(pentafluorophenyl)(6-hydroxy-2-naphthyl)borate, and the like.

[0127] Other preferred examples of non-coordinating anions include borates in which the hydroxy group of the above-exemplified borates is replaced with an NHR group, where R is preferably a methyl group, an ethyl group, or a tert-butyl group.

[0128] Furthermore, the proton-donating Bronsted acid is not particularly limited, but specific examples include trialkyl group-substituted ammonium cations such as triethylammonium, tripropylammonium, tri(n-butyl)ammonium, trimethylammonium, tributylammonium, and tri(n-octyl)ammonium; N,N-dialkylanilinium cations such as N,N-dimethylanilinium, N,N-diethylanilinium, N,N-2,4,6-pentamethylanilinium, and N,N-dimethylbenzylanilinium; dialkylammonium cations such as di-(i-propyl)ammonium and dicyclohexylammonium; triarylphosphonium cations such as triphenylphosphonium, tri(methylphenyl)phosphonium, and tri(dimethylphenyl)phosphonium; and dimethylsulfonium, diethylsulfonium, and diphenylsulfonium.

[0129] In this embodiment, an organometallic oxy compound having a unit represented by the following formula 11 can also be used as the activator. [ka] (where M 6 is a metal or metalloid of Groups 13 to 15 of the periodic table, and R 14 are each independently a hydrocarbon group or a substituted hydrocarbon group having 1 to 12 carbon atoms, and n is a metal M 6 where m is an integer of 2 or greater.)

[0130] A preferred example of the activator used in this embodiment is an organoaluminum oxy compound containing a unit represented by the following formula 12: [ka] (where R 15 is an alkyl group having 1 to 8 carbon atoms, and m is an integer of 2 to 60.

[0131] A more preferred example of the activator used in this embodiment is methylalumoxane containing a unit represented by the following formula 13: [ka] (where m is an integer from 2 to 60.) In this embodiment, the activator components may be used alone or in combination.

[0132] In the present embodiment, these catalyst components can also be used as supported catalysts by being supported on a solid component. Specific examples of such solid components include, but are not limited to, porous polymeric materials such as polyethylene, polypropylene, and styrene-divinylbenzene copolymers; inorganic solid materials of elements in Groups 2, 3, 4, 13, and 14 of the Periodic Table, such as silica, alumina, magnesia, magnesium chloride, zirconia, titania, boron oxide, calcium oxide, zinc oxide, barium oxide, vanadium pentoxide, chromium oxide, and thorium oxide, and mixtures thereof; and double oxides thereof.

[0133] The silica composite oxide is not particularly limited, but specific examples include composite oxides of silica and an element of Group 2 or Group 13 of the periodic table, such as silica magnesia and silica alumina. In addition to the above two catalyst components, an organoaluminum compound can be used as a catalyst component in this embodiment, if necessary. An example of an organoaluminum compound that can be used in this embodiment is a compound represented by the following formula 14: [ka] (where R 16 is an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 20 carbon atoms, and X 5 is a halogen, hydrogen or an alkoxyl group, the alkyl group is linear, branched or cyclic, and n is an integer of 1 to 3.

[0134] Here, the organoaluminum compound may be a mixture of compounds represented by the above formula 14. Examples of organoaluminum compounds that can be used in this embodiment include those represented by the above formula R 16 can be a methyl group, an ethyl group, a butyl group, an isobutyl group, a hexyl group, an octyl group, a decyl group, a phenyl group, a tolyl group, or the like; 5 Examples of the alkyl group include a methoxy group, an ethoxy group, a butoxy group, and a chlorine group.

[0135] The organoaluminum compound that can be used in the present embodiment is not particularly limited, but specific examples include trimethylaluminum, triethylaluminum, tributylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, and the like, as well as reaction products of these organoaluminum compounds with alcohols such as methyl alcohol, ethyl alcohol, butyl alcohol, pentyl alcohol, hexyl alcohol, octyl alcohol, and decyl alcohol, such as dimethylmethoxyaluminum, diethylethoxyaluminum, and dibutylbutoxyaluminum.

[0136] (Polymerization conditions) The polymerization temperature in the method for producing an ultra-high molecular weight polyethylene powder of this embodiment is usually 30°C or higher and 100°C or lower. A polymerization temperature of 30°C or higher tends to enable more efficient industrial production. On the other hand, a polymerization temperature of 100°C or lower tends to enable more stable continuous operation. Furthermore, the intrinsic viscosity IV of the ultra-high molecular weight polyethylene powder tends to decrease as the polymerization temperature increases, and tends to increase as the polymerization temperature decreases.

[0137] Furthermore, the polymerization pressure in the method for producing an ultra-high molecular weight polyethylene powder of this embodiment is typically atmospheric pressure or higher and 2 MPa or lower. The polymerization pressure is preferably 0.1 MPa or higher, more preferably 0.12 MPa or higher, and is preferably 1.5 MPa or lower, more preferably 1.0 MPa or lower. A polymerization pressure of atmospheric pressure or higher tends to enable industrially more efficient production, while a polymerization pressure of 2 MPa or lower tends to suppress local heat generation due to a rapid polymerization reaction upon introduction of the catalyst, thereby enabling stable production of polyethylene.

[0138] The polymerization reaction can be carried out in any of batch, semi-continuous, and continuous modes. From the viewpoint of controlling s within the above-mentioned range, a batch system is preferred. On the other hand, from the viewpoint of achieving a more uniform polymerization system, a continuous system is preferred. Continuously supplying ethylene gas, solvent, catalyst, etc. to the polymerization system and continuously discharging them together with the produced polyethylene makes it possible to suppress localized high-temperature conditions caused by a rapid ethylene reaction, thereby further stabilizing the polymerization system. When ethylene reacts in a uniform system, the formation of branches and double bonds in the polymer chain is suppressed, making it less likely that the polyethylene will become low-molecular-weight or crosslinked. This reduces the amount of unmelted material remaining when the ultra-high molecular weight polyethylene powder is melted or dissolved, suppressing coloration and reducing the occurrence of problems such as a decrease in mechanical properties.

[0139] The polymerization can also be carried out in two or more stages with different reaction conditions. Furthermore, as described in, for example, West German Patent Application Publication No. 3127133, the intrinsic viscosity of the resulting polyethylene can be adjusted by adding hydrogen to the polymerization system or by changing the polymerization temperature. The intrinsic viscosity can be controlled within an appropriate range by adding hydrogen as a chain transfer agent to the polymerization system. Adding a chain transfer agent tends to lower the intrinsic viscosity IV of the ultra-high molecular weight polyethylene produced at the same polymerization temperature. When hydrogen is added to the polymerization system, the molar fraction of hydrogen is preferably 0 mol% or more and 30 mol% or less, more preferably 0 mol% or more and 25 mol% or less, and even more preferably 0 mol% or more and 20 mol% or less. In addition to the components described above, this embodiment can also contain other known components useful for the production of polyethylene.

[0140] As mentioned above, when producing ethylene polymers, the particle diameter D can be reduced by (1) polymerizing a very small amount of comonomer by mixing it into ethylene and drying the polymerized powder at 100°C or higher, or (2) polymerizing in a state where a plasticizer is added to the polymerization solvent, removing the plasticizer from the powder after the polymerization is completed, setting the catalytic activity during polymerization (weight of polyethylene obtained per unit weight of catalyst) to 5000 (g-PE / g-catalyst) or less, and drying the polymerized powder at 70°C or less. 10 , D 50 and D 90 The average swelling starting temperature of the ultra-high molecular weight polyethylene powder can be controlled within the above range.

[0141] When an ethylene polymer is produced by the above method (1), the comonomer concentration in the gas phase is preferably 0.01 to 0.05 mol %.

[0142] When an ethylene polymer is produced by the above method (2), the amount of plasticizer added to the polymerization solvent is preferably 30 to 50% by mass, more preferably 35 to 45% by mass.

[0143] When an ethylene polymer is produced by the above method (1), the drying temperature of the polymer powder is preferably 100°C or higher, more preferably 105°C or higher.

[0144] When an ethylene polymer is produced by the above method (2), the drying temperature of the polymer powder is preferably 70°C or lower, more preferably 65°C or lower.

[0145] When an ethylene polymer is produced by the above method (2), the catalytic activity during polymerization is preferably 5000 (g-PE / g-catalyst) or less, and more preferably 4000 (g-PE / g-catalyst) or less.

[0146] When polymerizing the ultra-high molecular weight polyethylene powder of this embodiment, an antistatic agent such as Stadis 450 manufactured by The Associated Octel Company (distributor: Maruwa Bussan) can be used to prevent polymer adhesion to the polymerization reactor. Stadis 450 can also be diluted in an inert hydrocarbon medium and added to the polymerization reactor by a pump or the like. In this case, the amount added is preferably in the range of 0.10 ppm to 20 ppm, more preferably 0.20 ppm to 10 ppm, relative to the amount of polyethylene produced per unit time.

[0147] [Additives] Additives such as slip agents, neutralizing agents, antioxidants, light stabilizers, antistatic agents, and pigments may be added to the ultra-high molecular weight polyethylene powder of this embodiment as needed.

[0148] The slip agent or neutralizing agent is not particularly limited, but examples thereof include aliphatic hydrocarbons, higher fatty acids, higher fatty acid metal salts, fatty acid esters of alcohols, waxes, higher fatty acid amides, silicone oils, and rosins. Specific examples thereof include, but are not particularly limited to, calcium stearate. The content of the slip agent or neutralizing agent is not particularly limited, but is preferably 5000 ppm or less, more preferably 4000 ppm or less, and even more preferably 3000 ppm or less.

[0149] The antioxidant is not particularly limited, but for example, a phenol-based compound or a phenol-phosphate-based compound is preferable. Specific examples include phenolic antioxidants such as 2,6-di-t-butyl-4-methylphenol (dibutylhydroxytoluene), n-octadecyl-3-(4-hydroxy-3,5-di-t-butylphenyl)propionate, and tetrakis(methylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate))methane; phenol-phosphorus antioxidants such as 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphosphepine; and phosphorus-based antioxidants such as tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene-diphosphonite, tris(2,4-di-t-butylphenyl)phosphite, and cyclic neopentanetetraylbis(2,4-t-butylphenylphosphite).

[0150] In the ultra-high molecular weight polyethylene powder according to this embodiment, the amount of antioxidant is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, even more preferably 3 parts by mass or less, and particularly preferably 2 parts by mass or less, when the total amount of the ultra-high molecular weight polyethylene powder and the plasticizer is 100 parts by mass. When the amount of antioxidant is 5 parts by mass or less, deterioration of the polyethylene is suppressed, and embrittlement, discoloration, deterioration of mechanical properties, etc. are less likely to occur, resulting in better long-term stability.

[0151] The light resistance stabilizer is not particularly limited, but examples thereof include benzotriazole-based light resistance stabilizers such as 2-(5-methyl-2-hydroxyphenyl)benzotriazole and 2-(3-t-butyl-5-methyl-2-hydroxyphenyl)-5-chlorobenzotriazole, and hindered amine-based light resistance stabilizers such as bis(2,2,6,6-tetramethyl-4-piperidine)sebacate and poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}]. The content of the light resistance stabilizer is not particularly limited, but is 5000 ppm or less, preferably 3000 ppm or less, and more preferably 2000 ppm or less.

[0152] The antistatic agent is not particularly limited, but examples thereof include aluminosilicate, kaolin, clay, natural silica, synthetic silica, silicates, talc, diatomaceous earth, and glycerin fatty acid esters.

[0153] [Molded body] The ultra-high molecular weight polyethylene powder of this embodiment can be molded by various methods. Furthermore, a molded article of this embodiment can be obtained by molding the above-described ultra-high molecular weight polyethylene powder. The molded article of this embodiment can be used for various applications. Specific examples of the molded article of this embodiment include, but are not limited to, separators for secondary batteries (e.g., microporous membranes) and fibers (e.g., high-strength fibers), and are particularly suitable as microporous membranes and high-strength fibers for lithium-ion secondary battery separators.

[0154] The method for producing a secondary battery separator (e.g., a microporous membrane) is not particularly limited, but examples thereof include a wet method using a solvent, which involves extrusion, stretching, extraction, and drying using an extruder equipped with a T-die. Specific examples thereof include, but are not particularly limited to, a production method under the following general swelling conditions and a production method under the following low-temperature swelling conditions.

[0155] (General swelling conditions) Ultra-high molecular weight polyethylene powder, liquid paraffin, and, if necessary, additives such as antioxidants are mixed together and stirred at a temperature 30°C lower than the melting point (Tm2) of the ultra-high molecular weight polyethylene powder to prepare a slurry liquid. The resulting slurry liquid is placed in a kneader and kneaded at a constant temperature, followed by hot pressing and then cold pressing to form a gel sheet. The thickness of the gel sheet is adjusted using a metal frame. The gel-like sheet was stretched using a simultaneous biaxial stretching machine, and the stretched film was cut out and fixed to a metal frame. The film was then immersed in hexane to extract and remove the liquid paraffin, followed by drying. Further heat setting yielded a microporous membrane for secondary battery separators.

[0156] (Low temperature swelling conditions) A microporous membrane for secondary battery separator can be obtained in the same manner as above (general swelling conditions), except that the conditions for pre-impregnating the powder with liquid paraffin are changed to a temperature 50°C lower than the melting point (Tm2) of the ultra-high molecular weight polyethylene powder.

[0157] The method for producing fibers (e.g., high-strength fibers) is not particularly limited, but examples thereof include a method of kneading and spinning liquid paraffin and the above-mentioned ultra-high molecular weight polyethylene powder, followed by heating and drawing. Specific examples thereof include, but are not particularly limited to, a production method under the following general swelling conditions and a production method under the following low-temperature swelling conditions.

[0158] (General swelling conditions) Ultra-high molecular weight polyethylene powder, liquid paraffin, and, if necessary, additives such as antioxidants are mixed together and stirred at a temperature 30°C lower than the melting point (Tm2) of the ultra-high molecular weight polyethylene powder to prepare a slurry liquid. Next, the slurry liquid is charged into a kneading machine and kneading is carried out at a constant temperature. The mixture is then passed through a spinneret attached to the tip of the extruder and spun into fibers. The yarn containing the extruded liquid paraffin was then wound up at a location away from the spinneret. Next, in order to remove the liquid paraffin from the wound yarn, the yarn is immersed in hexane for extraction, and then dried. The obtained yarn is first drawn in a thermostatic bath, and then secondly drawn in the thermostatic bath until the yarn breaks, thereby obtaining a high-strength fiber (drawn yarn).

[0159] (Low temperature swelling conditions) High-strength fibers can be obtained in the same manner as above (general swelling conditions), except that the conditions for pre-impregnating the powder with liquid paraffin are changed to a temperature 50°C lower than the melting point (Tm2) of the ultra-high molecular weight polyethylene powder. [Example]

[0160] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples. The following examples were carried out at room temperature unless otherwise specified.

[0161] In the present application, the ethylene and hexane used in the examples and comparative examples were dehydrated using MS-3A (manufactured by Showa Union), and hexane was further deoxygenated by degassing under reduced pressure using a vacuum pump before use.

[0162] [Measurement method and conditions] The physical properties of the ultra-high molecular weight polyethylene powders of the Examples and Comparative Examples were measured by the following methods.

[0163] (1) Intrinsic viscosity IV The intrinsic viscosity IV of the ultra-high molecular weight polyethylene powders obtained in the Examples and Comparative Examples was measured in accordance with ISO1628-3 (2010) as follows. Polyethylene powder was weighed in the range of 4.0 to 4.5 mg and dissolved in 20 mL of decahydronaphthalene (2,6-di-t-butyl-4-methylphenol added at 1 g / L, hereafter referred to as decalin) as a solvent, which had been degassed with a vacuum pump and replaced with nitrogen, at 150 °C for 90 minutes under stirring in a dissolution tube whose interior air had been degassed with a vacuum pump and replaced with nitrogen. A Cannon-Fenske viscometer (Shibata Scientific Instruments Co., Ltd.: Product No. -100) was used as the viscometer.

[0164] (2)D 10 , D 50 and D 90 Measurement method The particle sizes of the ultra-high molecular weight polyethylene powders obtained in the examples and comparative examples were measured using a laser particle size distribution analyzer (SALD-2100 manufactured by Shimadzu Corporation) with methanol as a dispersion medium. Based on the measurements, a cumulative particle size distribution was created from the small particle size side, and the particle sizes at 10%, 50%, and 90% of the cumulative size were designated D. 10 , D 50 and D 90 It was decided.

[0165] (3) Swelling start temperature T 10 , T 50 , T 90 Measurement method and its average value T S Calculation method Particle diameter is D 10 The swelling start temperature T of the powder is 10 First, the major axis diameter and minor axis diameter (the plane figure of the particle observed using an optical microscope is image-processed, and the shortest distance between parallel lines obtained is taken as the minor axis diameter of the particle, and the longest distance between parallel lines in the direction perpendicular to that is taken as the major axis diameter of the particle) were calculated. 10One particle of ultra-high molecular weight polyethylene powder was randomly selected while checking the particle size within a ±10% range using an optical microscope. One particle of the selected ultra-high molecular weight polyethylene powder (hereinafter referred to as the "measured particle") was placed on a glass slide. 0.05 mL of liquid paraffin (P-350P, manufactured by MORESCO Corporation) was dripped onto the particle using a 1 mL syringe, and a cover glass was placed on top to sandwich the particle. The slide was then placed on a heat stage (10083L, manufactured by Japan High-Tech Co., Ltd.) and heated from room temperature to 150 °C under the following heating conditions. Images of the particle during heating were captured every 6 seconds using a camera-equipped optical microscope (BX51N, manufactured by Olympus Corporation). The equivalent circle diameter of the particle was calculated from each image obtained using image processing. The minimum temperature at which the equivalent circle diameter of the particle increased by 1% or more within the temperature range of 80 °C to 150 °C, based on the equivalent circle diameter of the particle at 80 °C, was defined as the swelling onset temperature of the particle. Measurements were taken at 10 points, and the average value was calculated as the swelling starting temperature T 10 It was decided. Next, the particle diameter is D 50 The swelling onset temperature T of ultra-high molecular weight polyethylene powder is 50 , and particle diameter is D 90 The swelling onset temperature T of ultra-high molecular weight polyethylene powder is 90 Regarding the swelling starting temperature T 10 Similarly, the major and minor axis diameters are D 50 Ultra-high molecular weight polyethylene powder within the range of ±10%, and the major and minor axis diameters are D 90 The measurement was carried out using ultra-high molecular weight polyethylene powder within a range of ±10%. Finally, the swelling starting temperature T 10 , T 50 , T 90 The average value of T S was calculated as follows:

number

number

[0166] (4) Ti, Al, and Si contents in ultra-high molecular weight polyethylene powder The ultra-high molecular weight polyethylene powders obtained in the examples and comparative examples were pressure-decomposed using a microwave decomposition apparatus (model ETHOS TC, manufactured by Milestone General Co., Ltd.), and the element concentrations of titanium (Ti), aluminum (Al), and silicon (Si) as metals contained in the ultra-high molecular weight polyethylene powder were measured using an ICP-MS (inductively coupled plasma mass spectrometer, model X Series X7, manufactured by Thermo Fisher Scientific Co., Ltd.) by the internal standard method.

[0167] (5) Manufacturing method of microporous membrane for secondary battery separator (general swelling conditions) Using the ultra-high molecular weight polyethylene powders obtained in the Examples and Comparative Examples, microporous membranes for secondary battery separators were produced as follows. When the total amount of ultra-high molecular weight polyethylene powder and liquid paraffin was 100 parts by mass, 30 parts by mass of ultra-high molecular weight polyethylene powder, 70 parts by mass of liquid paraffin (liquid paraffin manufactured by MORESCO Corporation (product name: Smoil P-350P)), and 1 part by mass of antioxidant (tetrakis[methylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate)]methane (product name: ANOX20) manufactured by Great Lakes Chemical Japan Co., Ltd.) were blended, and a slurry liquid was prepared by stirring for 30 minutes at a temperature 30°C lower than the melting point (Tm2) of the ultra-high molecular weight polyethylene powder. The resulting slurry was placed in a Toyo Seiki Labo Plastomill (model: 4C150-01) and mixed at a constant temperature of 200°C for 10 minutes at a screw speed of 50 rpm. The mixture was then heat-pressed at 180°C / 1 MPa / 3 minutes, then at 180°C / 10 MPa / 2 minutes, and then cold-pressed at 25°C / 10 MPa / 5 minutes to form a gel sheet. The gel sheet was adjusted to a thickness of 1.0 mm using a metal frame measuring 20 cm long, 20 cm wide, and 1.0 mm thick. This gel-like sheet was cut into a 9.5 cm x 9.5 cm square and stretched 7 x 7 times at 115°C using a simultaneous biaxial stretching machine. The stretched film was then cut into approximately 30 cm square pieces and fixed in a metal frame with inner dimensions of 25 cm square. The film was then immersed in hexane to extract and remove the liquid paraffin, and then dried at room temperature for 24 hours. It was then heat-set at 134°C for 1 minute to obtain a microporous membrane for secondary battery separators.

[0168] (6) Manufacturing method of microporous membrane for secondary battery separator (low-temperature swelling conditions) A microporous membrane for secondary battery separator was obtained in the same manner as in (5) above, except that the conditions for pre-impregnating the powder with liquid paraffin were changed to stirring for 30 minutes at a temperature 50°C lower than the melting point (Tm2) of the ultra-high molecular weight polyethylene powder.

[0169] (7) Number of defects in microporous membranes for secondary battery separators A microporous membrane for a secondary battery separator is produced by the method described in (5) or (6) above, and 1 m of the obtained microporous membrane is 2 Defects of 50 μm or larger present in each microporous membrane (16 sheets of 25 cm square microporous membrane) were counted visually, or using a magnifying glass if necessary. "Defects" here refer to areas that are darker in color than normal areas when the microporous membrane is observed with transmitted light (poor dispersion); fibers and colored foreign matter are not counted as defects. Based on the number of defects found, the number of defects, which is one indicator of the quality of the microporous membrane, was evaluated according to the following evaluation criteria. (Evaluation criteria) ◎:15 pieces / m 2 less than ○:15 pieces / m 2 More than 45 pieces / m 2 less than △:45 pieces / m 2 More than 90 pieces / m 2 less than ×:90 pieces / m 2 End

[0170] (8) Thickness variation of microporous membranes for secondary battery separators A microporous membrane for secondary battery separator was produced by the method described in (5) or (6) above, and the thickness of the resulting microporous membrane was measured using a film thickness meter based on JIS K7130. A 25 cm square microporous membrane was cut into 25 5 cm square microporous membranes, and the center of each was measured to calculate the average membrane thickness. Thickness variation (uneven membrane thickness), which is an index of the quality of a microporous membrane, was evaluated based on the average membrane thickness as follows: (Evaluation criteria) ◎: Variation of less than ±1.5 μm from the average film thickness ○: Variation of the average film thickness is between ±1.5 μm and ±2.0 μm △: Variation of the average film thickness between ±2.0 μm and 4.0 μm ×: Variation of ±4.0 μm or more from the average film thickness

[0171] (9) Puncture strength (gf / (g / m) of microporous membrane for secondary battery separator 2 )) Using a handy compression tester "KES-G5" manufactured by Kato Tech Co., Ltd., the microporous membrane for secondary battery separator described in (5) or (6) above was fixed with a sample holder having an opening diameter of 10 mm. Next, a puncture test was performed on the center of the fixed microporous membrane with a needle tip curvature radius of 0.5 mm and a puncture speed of 10 mm / min to obtain the puncture strength (gf) as the maximum puncture load. The obtained puncture strength (gf) was expressed as basis weight (g / m 2 ) to obtain the basis weight converted strength (gf / (g / m 2 This procedure was repeated eight times with eight microporous membranes, and the average of the eight measurements was used to calculate the basis weight converted strength (gf / (g / m 2 )) and evaluated according to the following criteria. (Evaluation criteria) ◎: 80gf / (g / m2 ) End ○: 70gf / (g / m 2 ) or more 80gf / (g / m 2 )less than △: 60gf / (g / m 2 ) or more 70gf / (g / m 2 )less than ×: 60gf / (g / m 2 )less than

[0172] (10) Heat shrinkage rate of microporous membrane for secondary battery separator When producing the microporous membrane for secondary battery separator described in (5) or (6) above, the heat setting was carried out under four conditions: 130°C / 1 minute, 132°C / 1 minute, 134°C / 1 minute, and 136°C / 1 minute, and the porosity of the obtained membrane after heat setting was calculated. The porosity was determined by cutting a 10 cm x 10 cm square sample from the microporous membrane and measuring its volume (cm 3 ) and mass (g), and compare them with the density of polyethylene (g / cm 3 ) was calculated using the following formula: Porosity (%) = (volume - mass / density) / volume x 100 The heat-set membranes were sandwiched between sheets of paper, the stack of papers was placed in an envelope, and heated at 120°C for 1 hour. The membranes were then cooled at room temperature for 15 minutes. The length of each side of the membrane was measured with a curved ruler, the average value was calculated, and the shrinkage rate from the original length (10 cm) was calculated to calculate the thermal shrinkage rate. A graph of porosity and thermal shrinkage rate was then created, and the thermal shrinkage rate at a porosity of 50% was roughly calculated from the graph. The membrane properties were evaluated based on the obtained thermal shrinkage rate using the following criteria. (Evaluation criteria) ◎: Less than 20% ○: 20% or more but less than 25% △: 25% or more but less than 30% ×: 30% or more

[0173] (11) Manufacturing method of high-strength fiber (general swelling conditions) High-strength fibers were produced using ultra-high molecular weight polyethylene powder as follows: 7 parts by mass of ultra-high molecular weight polyethylene powder, 93 parts by mass of liquid paraffin (liquid paraffin manufactured by MORESCO Corporation (product name: Smoil P-350P)), and 1 part by mass of antioxidant (tetrakis[methylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate)]methane (product name: ANOX20) manufactured by Great Lakes Chemical Japan Co., Ltd.) were blended, assuming a total of 100 parts by mass of ultra-high molecular weight polyethylene powder and liquid paraffin, and the mixture was stirred for 30 minutes at a temperature 30°C lower than the melting point (Tm2) of the ultra-high molecular weight polyethylene powder to prepare a slurry liquid. Next, the slurry liquid was charged into a counter-rotating twin-screw extruder (main body model: 2D25S) for a Laboplastomill (main body model: 4C150) manufactured by Toyo Seiki Co., Ltd., and kneaded at a constant temperature of 200°C. The mixture was then spun through a spinneret attached to the tip of the extruder at a temperature of 200°C, a throughput of 300 g / hour, and a hole diameter of 1.0 mm. Next, the extruded yarn containing liquid paraffin was wound up at a speed of 50 m / min at room temperature at a location 2.0 m away from the spinneret. Next, in order to remove the liquid paraffin from the wound yarn, the yarn was immersed in hexane for extraction, and then dried for 24 hours. The obtained yarn was first drawn at a speed of 20 mm / min in a thermostatic bath set at 120°C, and then secondarily drawn at a speed of 10 mm / min in a thermostatic bath set at 140°C until just before the yarn broke, to obtain a high-strength fiber (drawn yarn).

[0174] (12) Manufacturing method of high-strength fiber (low-temperature swelling conditions) High-strength fibers (drawn yarns) were obtained in the same manner as in (11) above, except that the conditions for pre-impregnating the powder with liquid paraffin were changed to stirring for 30 minutes at a temperature 50°C lower than the melting point (Tm2) of the ultra-high molecular weight polyethylene powder.

[0175] (13) Number of high-strength fiber clumps The number of clumps of yarn formed in 10 m of high-strength fiber (drawn yarn) spun by the method described in (11) or (12) above was counted, and the number of clumps was calculated. The term "clumps" used here refers to areas that are locally thicker than normal areas (poor dispersion). Based on the calculated number of clumps, the quality of the high-strength fiber was evaluated as follows: (Evaluation criteria) ◎: Number of clumps is less than 3 / m ○: Number of thread clumps is 3 or more but less than 6 / m △: Number of thread clumps is 6 or more but less than 10 / m ×: Number of clumps is 10 or more per meter

[0176] (14) Uneven diameter of high-strength fibers The diameter of 10 m of high-strength fiber (drawn fiber) spun by the method described in (11) or (12) above was measured at 0.5 m intervals using an optical microscope, and the average fiber diameter was calculated. Using this average fiber diameter as a standard, the fiber diameter unevenness, which is one of the qualities of high-strength fiber, was evaluated as follows. (Evaluation criteria) ◎: Variation of less than ±3 μm from the average fiber diameter ○: Variation of ±3 μm or more and less than ±5 μm from the average fiber diameter △: Variation of ±5 μm or more and less than 10 μm from the average fiber diameter ×: Variation of ±10 μm or more from the average fiber diameter

[0177] (15) Tensile breaking strength of high-strength fibers Ten meters of high-strength fiber (drawn yarn) spun by the method described in (11) or (12) above was cut at 1-meter intervals, and 10 of the resulting fibers were pulled until they broke at room temperature, and the average breaking strength was calculated. The breaking strength was calculated by dividing the maximum load applied to the yarn by the fineness. Here, fineness refers to the number of fibers per 1 × 10 4 The weight (g) per meter was calculated from the weight of 10 m of high-strength fiber. The unit of fineness is dtex. A balance capable of measuring to the nearest 0.1 mg was used to measure the weight. The tensile breaking strength of the high strength fibers was evaluated according to the following criteria. (Evaluation criteria) ◎: Breaking strength 30cN / dtex or more ○: Breaking strength 25cN / dtex or more, less than 30cN / dtex △: Breaking strength 20cN / dtex or more, less than 25cN / dtex ×: Breaking strength less than 20 cN / dtex

[0178] (16) Melting point of ultra-high molecular weight polyethylene powder (Tm2) The melting points (Tm2) of the ultra-high molecular weight polyethylene powders obtained in the examples and comparative examples were measured as follows using a Perkin Elmer DSC8000 differential scanning calorimeter (DSC). 8.3 to 8.5 mg of polyethylene polymer powder was weighed and placed in an aluminum sample pan. An aluminum cover was attached to this pan, which was then placed in a differential scanning calorimeter. Measurements were carried out under the following conditions while purging with nitrogen at a flow rate of 20 mL / min. Pure indium was used for temperature calibration. 1) After holding at 50°C for 1 minute, the temperature was increased to 180°C at a rate of 10°C / min. 2) After holding at 180°C for 5 minutes, the temperature was lowered to 50°C at a rate of 10°C / min. 3) After holding at 50°C for 5 minutes, the temperature was increased to 180°C at a rate of 10°C / min. The peak top temperature of the melting curve obtained during the temperature increase process in 3) above was taken as the melting point (Tm2).

[0179] [Catalyst synthesis method] [Production Example 1] (Preparation of supported metallocene catalyst component [A]) (1) Synthesis of raw material [a-1] Average particle size is 7 μm and surface area is 700 m 2 Spherical silica with a particle size of 1.9 mL / g and an intraparticle pore volume of 1.9 mL / g was calcined at 500°C for 5 hours in a nitrogen atmosphere and dehydrated. In a nitrogen atmosphere, 40 g of this dehydrated silica was dispersed in 800 mL of hexane in a 1.8 L capacity autoclave to obtain a slurry. While the obtained slurry was kept at 20° C. under stirring, 100 mL of a hexane solution of triethylaluminum (concentration: 1 mol / L) was added dropwise over 1 hour, and then the mixture was stirred at the same temperature for 2 hours. The resulting reaction mixture was then decanted to remove unreacted triethylaluminum from the supernatant, yielding 800 mL of a hexane slurry of the silica component [a-1] treated with triethylaluminum. (2) Preparation of raw material [a-2] 200 mmol of [(Nt-butylamido)(tetramethyl-η5-cyclopentadienyl)dimethylsilane]titanium-1,3-pentadiene (hereinafter referred to as "titanium complex") was dissolved in 1250 mL of Isopar E [a trade name for a hydrocarbon mixture manufactured by Exxon Chemical Company (USA)], and 25 mL of a 1 mol / L hexane solution of commercially available butylethylmagnesium was added. Further hexane was added to adjust the titanium complex concentration to 0.1 mol / L, thereby obtaining titanium complex [a-2]. (3) Preparation of raw material [a-3] 5.7 g of bis(hydrogenated tallow alkyl)methylammonium-tris(pentafluorophenyl)(4-hydroxyphenyl)borate (hereinafter referred to as "borate") was added and dissolved in 50 mL of toluene to obtain a 100 mmol / L toluene solution of borate. 5 mL of a 1 mol / L hexane solution of ethoxydiethylaluminum was added to this toluene solution at room temperature, and further hexane was added to adjust the borate concentration in the solution to 70 mmol / L. The mixture was then stirred at room temperature for 1 hour to obtain a reaction mixture [a-3] containing borate. (4) Synthesis of supported metallocene catalyst [A] While stirring at 20°C, 800 mL of the silica component [a-1] slurry obtained in (1) above was simultaneously added over 1 hour with 32 mL of the titanium complex [a-2] obtained in (2) above and 46 mL of the borate-containing reaction mixture [a-3] obtained in (3) above. The mixture was stirred at the same temperature for another 1 hour to allow the titanium complex and borate to react with each other. The catalytic activity could be controlled by adjusting the amounts of the titanium complex [a-2] and the borate-containing reaction mixture [a-3]. Specifically, increasing these amounts tends to increase the catalytic activity. After the reaction was completed, the supernatant was removed, and unreacted catalyst raw materials were removed with hexane to obtain a supported metallocene catalyst [A] (hereinafter also referred to as solid catalyst component [A]) in which catalytically active species were formed on the silica. (5) Synthesis of raw material (a-4) In an 8L stainless steel autoclave that has been thoroughly purged with nitrogen, add 1 mol / L of Mg6(C4H9) 12 2,000 mL of a hexane solution of Al(C2H5)3 (equivalent to 2,000 mmol of magnesium and aluminum) was charged and stirred at 80°C. 240 mL of a hexane solution of 8.33 mol / L methylhydrogenpolysiloxane (Shin-Etsu Chemical Co., Ltd.) was pressure-fed, and stirring was continued at 80°C for another 2 hours. After the reaction was completed, the mixture was cooled to room temperature and used as raw material (a-4). The total concentration of magnesium and aluminum in raw material (a-4) was 0.786 mol / L.

[0180] [Production Example 2] (Preparation of solid catalyst component [B]) (1) Synthesis of raw material (b-1) In an 8L stainless steel autoclave that has been thoroughly purged with nitrogen, add 1 mol / L of Mg6(C4H9) 122,000 mL of a hexane solution of Al(C2H5)3 (equivalent to 2,000 mmol of magnesium and aluminum) was charged, and 146 mL of a 5.47 mol / L n-butanol hexane solution was added dropwise over 3 hours while stirring at 50°C. After the addition was complete, the line was washed with 300 mL of hexane. The reaction was continued for another 2 hours while stirring at 50°C. After the reaction was complete, the mixture was cooled to room temperature and used as raw material (b-1). The magnesium concentration of raw material (b-1) was 0.704 mol / L. (2) Synthesis of raw material (b-2) In an 8L stainless steel autoclave that has been thoroughly purged with nitrogen, add 1 mol / L of Mg6(C4H9) 12 2,000 mL of a hexane solution of Al(C2H5)3 (equivalent to 2,000 mmol of magnesium and aluminum) was charged and stirred at 80°C. 240 mL of a hexane solution of 8.33 mol / L methylhydrogenpolysiloxane (Shin-Etsu Chemical Co., Ltd.) was pressure-fed, and the reaction was continued for another 2 hours at 80°C with stirring. After the reaction was completed, the mixture was cooled to room temperature and used as raw material (b-2). The total concentration of magnesium and aluminum in raw material (b-2) was 0.786 mol / L. (3) (B-1) Synthesis of the carrier An 8L stainless steel autoclave was charged with 1,000mL of a 1mol / L hydroxytrichlorosilane hexane solution, and 1,340mL of the hexane solution of the organomagnesium compound (b-1) (equivalent to 943mmol of magnesium) was added dropwise over 3 hours at 65°C. The reaction was continued for another 1 hour with stirring at 65°C. After the reaction was completed, the supernatant was removed and the mixture was washed four times with 1,800mL of hexane to obtain the (B-1) carrier. Analysis of this carrier revealed that the magnesium content per gram of solid was 7.5mmol. (4) Preparation of solid catalyst component [B] To 1,970 mL of hexane slurry containing 110 g of the above (B-1) carrier, 103 mL of a 1 mol / L hexane solution of titanium tetrachloride and 131 mL of raw material (b-2) were added simultaneously over 3 hours while stirring at 10°C. The catalytic activity can be controlled by adjusting the amounts of the hexane solution of titanium tetrachloride and raw material (b-2). Specifically, increasing these amounts tends to increase the catalytic activity. After addition, the reaction was continued for 1 hour at 10°C. After completion of the reaction, the supernatant was removed, and the unreacted raw material components were removed by washing four times with hexane to prepare solid catalyst component [B].

[0181] [Production Example 3] (Preparation of solid catalyst component [C]) (1) Synthesis of raw material (c-1) In an 8L stainless steel autoclave that has been thoroughly purged with nitrogen, add 1 mol / L of Mg6(C4H9) 12 2,000 mL of a hexane solution of Al(C2H5)3 (equivalent to 2,000 mmol of magnesium and aluminum) was charged and stirred at 80°C. 240 mL of a hexane solution of 8.33 mol / L methylhydrogenpolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd.) was pressure-fed, and the reaction was continued for another 2 hours at 80°C with stirring. After the reaction was completed, the mixture was cooled to room temperature and used as raw material (c-1). The total concentration of magnesium and aluminum in raw material (c-1) was 0.786 mol / L. (2) Preparation of solid catalyst component [C] 1,600 mL of hexane was added to an 8 L stainless steel autoclave purged with nitrogen. While stirring at 10°C, 800 mL of a 1 mol / L hexane solution of titanium tetrachloride and 800 mL of raw material (c-1) were added simultaneously over 5 hours. The reaction was continued at 10°C for 1 hour. After the reaction was completed, the supernatant was removed and the mixture was washed four times with hexane to remove unreacted raw material components, preparing solid catalyst component [C]. The catalytic activity of this catalyst can be adjusted by the polymerization pressure during polymerization.

[0182] [catalyst] Catalyst 1: Solid catalyst component [C] synthesized according to the above Production Example 3 Catalyst 2-1: Solid catalyst component [B] synthesized in the same manner as in Production Example 2 above, using 103 mL of a hexane solution of titanium tetrachloride and 131 mL of raw material (b-2). Catalyst 2-2: Solid catalyst component [B] synthesized in the same manner as in Production Example 2 above, except that the amount of the hexane solution of titanium tetrachloride was 21 mL and the amount of raw material (b-2) was 26 mL. Catalyst 3-1: Solid catalyst component [A] synthesized using 32 mL of titanium complex [a-2] and 46 mL of reaction mixture [a-3] as in Production Example 1 above. Catalyst 3-2: Solid catalyst component [A] synthesized in the same manner as in Production Example 1 above, except that the amount of titanium complex [a-2] was 19.2 mL and the amount of reaction mixture [a-3] was 27.6 mL.

[0183] [Cocatalyst] Cocatalyst 1: A mixture of commercially available triisobutylaluminum and diisobutylaluminum hydride (a 9:1 mass ratio mixture). Cocatalyst 2: Mg6(C4H9) 12 AL(C2H5)3 Co-catalyst 3: the above-synthesized raw material (a-4), raw material (b-2), or raw material (c-1)

[0184] [Example 1] A 1.5 L vessel-type polymerization reactor equipped with a stirrer was evacuated and 500 mL of dehydrated normal hexane was introduced into the reactor. Next, 0.6 mL of cocatalyst 1 was dispersed in 100 mL of dehydrated normal hexane and introduced into the reactor. The temperature of the polymerization reactor was adjusted to 80 °C, and stirring was initiated at 1,000 rpm. Hydrogen was then introduced to adjust the intrinsic viscosity IV (molecular weight) until the pressure inside the polymerization reactor reached 0.045 MPa. Ethylene and 0.05 mol% 1-butene (comonomer) were then introduced into the polymerization reactor through separate lines until the pressure inside the polymerization reactor reached 0.1 MPa. Next, 20.0 mg of catalyst 1 was dispersed in 200 mL of dehydrated normal hexane and introduced into the polymerization reactor. A batch polymerization reaction was carried out for 1.0 hour. During the polymerization reaction, the pressure inside the polymerization reactor was maintained by appropriately adding ethylene and comonomer to the polymerization reactor. The polymerization reactor was then opened, and the contents were filtered under reduced pressure to separate and recover the powdery solid component. The resulting solid component was placed in a 68 mm stainless steel beaker and dried at 100 °C for 2.0 hours to obtain ultra-high molecular weight polyethylene powder. The yield of ultra-high molecular weight polyethylene powder was 82.0 g, and the catalytic activity (amount of polyethylene obtained per unit catalyst weight) was 4100 (g-PE / g-catalyst). Scale and extremely coarse particles were removed using a 425 μm mesh sieve, and 600 ppm of calcium stearate was added. The physical properties of the ultra-high molecular weight polyethylene powder were then evaluated. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 1. The obtained ultra-high molecular weight polyethylene powder was used to produce a microporous membrane for a secondary battery separator by the method described in (5) or (6) above. The evaluation results of the obtained microporous membrane are shown in Table 1.

[0185] [Example 2] A 1.5 L vessel-type polymerization reactor equipped with a stirrer was evacuated and 500 mL of dehydrated normal hexane was introduced into the reactor. Next, 0.6 mL of cocatalyst 1 was dispersed in 100 mL of dehydrated normal hexane and introduced into the reactor. The temperature of the polymerization reactor was adjusted to 80 °C, and stirring was initiated at 1,000 rpm. Hydrogen was then introduced to adjust the intrinsic viscosity IV (molecular weight) until the pressure inside the polymerization reactor reached 0.12 MPa. A mixed gas prepared by premixing ethylene with 0.05 mol% 1-butene (comonomer) was then introduced into the polymerization reactor until the pressure inside the polymerization reactor reached 0.4 MPa. Next, 10.0 mg of catalyst 2-1 was dispersed in 200 mL of dehydrated normal hexane and introduced into the polymerization reactor. A batch polymerization reaction was carried out for 1.0 hour. The pressure inside the polymerization reactor was maintained by appropriately introducing additional mixed gas into the polymerization reactor during the polymerization reaction. The polymerization reactor was then opened, and the contents were filtered under reduced pressure to separate and recover the powdery solid component. The resulting solid component was placed in a metal tray, spread evenly to a thickness of 5 mm, and dried at 100°C for 2.0 hours to obtain ultra-high molecular weight polyethylene powder. The yield of ultra-high molecular weight polyethylene powder was 185.5 g, and the catalytic activity (amount of polyethylene obtained per unit catalyst weight) was 18,550 (g-PE / g-catalyst). After removing scale and extremely coarse particles using a sieve with 425 μm openings, the ultra-high molecular weight polyethylene powder was evaluated for its physical properties. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 1. The obtained ultra-high molecular weight polyethylene powder was used to produce a microporous membrane for a secondary battery separator by the method described in (5) or (6) above. The evaluation results of the obtained microporous membrane are shown in Table 1.

[0186] [Example 3] A 1.5 L vessel-type polymerization reactor equipped with a stirrer was evacuated, and 500 mL of a mixed solvent (previously prepared by thoroughly mixing 70% by mass of dehydrated normal hexane and 30% by mass of liquid paraffin) was introduced into the reactor. Next, 0.6 mL of cocatalyst 1 was dispersed in 100 mL of dehydrated normal hexane and introduced into the reactor. The reactor temperature was adjusted to 80 °C, and stirring was initiated at 1,000 rpm. Hydrogen was then introduced to adjust the intrinsic viscosity IV (molecular weight) until the pressure inside the polymerization reactor reached 0.016 MPa, and ethylene gas was then introduced until the pressure inside the polymerization reactor reached 0.1 MPa. Next, 20.0 mg of catalyst 1 was dispersed in 200 mL of dehydrated normal hexane and introduced into the reactor. A batch polymerization reaction was carried out for 1.0 hour. During the polymerization reaction, the pressure inside the polymerization reactor was maintained by appropriately introducing additional ethylene gas into the polymerization reactor. The polymerization reactor was then opened, and the contents were filtered under reduced pressure to separate and recover the powdery solid component. The resulting solid component was placed in a 68 mm stainless steel beaker and dried at 70 °C for 1.5 hours to obtain ultra-high molecular weight polyethylene powder. The yield of ultra-high molecular weight polyethylene powder was 70.2 g, and the catalytic activity (amount of polyethylene obtained per unit catalyst weight) was 3510 (g-PE / g-catalyst). Scale and extremely coarse particles were removed using a 425 μm mesh sieve, and 1200 ppm of calcium stearate was added. The physical properties of the ultra-high molecular weight polyethylene powder were then evaluated. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 1. The obtained ultra-high molecular weight polyethylene powder was used to produce a microporous membrane for a secondary battery separator by the method described in (5) or (6) above. The evaluation results of the obtained microporous membrane are shown in Table 1.

[0187] [Example 4] A 1.5 L vessel-type polymerization reactor equipped with a stirrer was evacuated and 500 mL of dehydrated normal hexane was introduced into the reactor. Next, 0.6 mL of cocatalyst 1 dispersed in 100 mL of dehydrated normal hexane was introduced into the reactor. The temperature of the polymerization reactor was adjusted to 80 °C, and stirring was initiated at 1,000 rpm. Hydrogen was then introduced to adjust the intrinsic viscosity IV (molecular weight) until the pressure inside the polymerization reactor reached 0.0036 MPa. A mixed gas prepared by premixing ethylene with 0.05 mol% 1-butene (comonomer) was then introduced until the pressure inside the polymerization reactor reached 0.4 MPa. 6.0 mg of catalyst 1 dispersed in 200 mL of dehydrated normal hexane was then introduced into the polymerization reactor, and a batch polymerization reaction was carried out for 1.0 hour. The pressure inside the polymerization reactor was maintained by appropriately introducing additional mixed gas into the polymerization reactor during the polymerization reaction. The polymerization reactor was then opened, and the contents were filtered under reduced pressure to separate and recover the powdery solid component. The resulting solid component was placed in a metal tray, spread evenly to a thickness of 5 mm, and dried at 100°C for 5.0 hours to obtain ultra-high molecular weight polyethylene powder. The yield of ultra-high molecular weight polyethylene powder was 163.6 g, and the catalytic activity (amount of polyethylene obtained per unit catalyst weight) was 27,270 (g-PE / g-catalyst). After removing scale and extremely coarse particles using a 425 μm mesh sieve, 600 ppm of calcium stearate was added, and the physical properties of the ultra-high molecular weight polyethylene powder were evaluated. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 1. The obtained ultra-high molecular weight polyethylene powder was used to produce a microporous membrane for a secondary battery separator by the method described in (5) or (6) above. The evaluation results of the obtained microporous membrane are shown in Table 1.

[0188] [Example 5] A 1.5 L vessel-type polymerization reactor equipped with a stirrer was evacuated, and 500 mL of a mixed solvent (previously prepared by thoroughly mixing 70% by mass of dehydrated normal hexane and 30% by mass of liquid paraffin) was introduced into the reactor. Next, 0.6 mL of cocatalyst 1 was dispersed in 100 mL of dehydrated normal hexane and introduced into the reactor. The temperature of the polymerization reactor was adjusted to 80 °C, and stirring was initiated at 1,000 rpm. Hydrogen was then introduced to adjust the intrinsic viscosity IV (molecular weight) to a pressure of 0.0016 MPa. Ethylene and 3.0 mol% 1-butene (comonomer) were then introduced through separate lines to a pressure of 0.4 MPa. 20.0 mg of catalyst 2-2 was then dispersed in 200 mL of dehydrated normal hexane and introduced into the reactor. A batch polymerization reaction was carried out for 0.7 hours. During the polymerization reaction, the pressure inside the polymerization reactor was maintained by appropriately introducing ethylene and comonomer into the reactor. The reactor was then opened, and the contents were filtered under reduced pressure to separate and recover the powdery solid component. The resulting solid component was placed in a 68 mm stainless steel beaker and dried at 70 °C for 2.0 hours to obtain ultra-high molecular weight polyethylene powder. The yield of the ultra-high molecular weight polyethylene powder was 83.2 g, and the catalytic activity (amount of polyethylene obtained per unit catalyst weight) was 4160 (g-PE / g-catalyst). After removing scale and extremely coarse particles using a 425 μm mesh sieve, 1200 ppm of calcium stearate was added, and the physical properties of the ultra-high molecular weight polyethylene powder were evaluated. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 1. The obtained ultra-high molecular weight polyethylene powder was used to produce a microporous membrane for a secondary battery separator by the method described in (5) or (6) above. The evaluation results of the obtained microporous membrane are shown in Table 1.

[0189] [Example 6] A 1.5 L vessel-type polymerization reactor equipped with a stirrer was evacuated and 500 mL of dehydrated normal hexane was introduced into the reactor. Next, 0.6 mL of cocatalyst 3 was dispersed in 100 mL of dehydrated normal hexane and introduced into the reactor. The temperature of the polymerization reactor was adjusted to 80 °C, and stirring was initiated at 1,000 rpm. Hydrogen was then introduced to adjust the intrinsic viscosity IV (molecular weight) until the pressure inside the polymerization reactor reached 0.0008 MPa. A mixed gas prepared by premixing ethylene with 0.03 mol% 1-butene (comonomer) was then introduced into the polymerization reactor until the pressure inside the polymerization reactor reached 0.4 MPa. 20.0 mg of catalyst 3-1 was then dispersed in 200 mL of dehydrated normal hexane and introduced into the polymerization reactor. A batch polymerization reaction was carried out for 1.0 hour. The pressure inside the polymerization reactor was maintained by appropriately introducing additional mixed gas into the polymerization reactor during the polymerization reaction. The polymerization reactor was then opened, and the contents were filtered under reduced pressure to separate and recover the powdery solid component. The resulting solid component was placed in a metal tray, spread evenly to a thickness of 5 mm, and dried at 110°C for 2.5 hours to obtain ultra-high molecular weight polyethylene powder. The yield of the ultra-high molecular weight polyethylene powder was 144.0 g, and the catalytic activity (amount of polyethylene obtained per unit catalyst weight) was 7200 (g-PE / g-catalyst). After removing scale and extremely coarse particles using a sieve with 425 μm openings, 600 ppm of calcium stearate was added, and the physical properties of the ultra-high molecular weight polyethylene powder were evaluated. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 1. The obtained ultra-high molecular weight polyethylene powder was used to produce a microporous membrane for a secondary battery separator by the method described in (5) or (6) above. The evaluation results of the obtained microporous membrane are shown in Table 1.

[0190] [Example 7] A 1.5 L vessel-type polymerization reactor equipped with a stirrer was evacuated, and 500 mL of a mixed solvent (previously prepared by thoroughly mixing 70% by mass of dehydrated normal hexane and 30% by mass of liquid paraffin) was introduced into the reactor. Next, 0.6 mL of cocatalyst 1 was dispersed in 100 mL of dehydrated normal hexane and introduced into the reactor. The temperature of the polymerization reactor was adjusted to 78 °C, and stirring was initiated at 1,000 rpm. Hydrogen was then introduced to adjust the intrinsic viscosity (IV) (molecular weight) to a pressure of 0.000063 MPa. Ethylene and 5.0 mol% 1-butene (comonomer) were then introduced through separate lines to a pressure of 0.07 MPa. Next, 20.0 mg of catalyst 1 was dispersed in 200 mL of dehydrated normal hexane and introduced into the reactor. A batch polymerization reaction was carried out for 1.0 hour. During the polymerization reaction, the pressure inside the polymerization reactor was maintained by appropriately introducing ethylene and comonomer into the reactor. The reactor was then opened, and the contents were filtered under reduced pressure to separate and recover the powdery solid component. The resulting solid component was placed in a 68 mm stainless steel beaker and dried at 70 °C for 1.5 hours to obtain ultra-high molecular weight polyethylene powder. The yield of the ultra-high molecular weight polyethylene powder was 49.8 g, and the catalytic activity (amount of polyethylene obtained per unit catalyst weight) was 2490 (g-PE / g-catalyst). After removing scale and extremely coarse particles using a 425 μm mesh sieve, the ultra-high molecular weight polyethylene powder was evaluated for its physical properties. The evaluation results for the ultra-high molecular weight polyethylene powder are shown in Table 2. The obtained ultra-high molecular weight polyethylene powder was used to produce high strength fibers by the method described in (11) or (12) above. The evaluation results of the obtained high strength fibers are shown in Table 2.

[0191] [Example 8] A 1.5 L vessel-type polymerization reactor equipped with a stirrer was evacuated and 500 mL of dehydrated normal hexane was introduced into the reactor. Next, 0.6 mL of cocatalyst 2 was dispersed in 100 mL of dehydrated normal hexane and introduced into the reactor. The temperature of the polymerization reactor was adjusted to 78 °C, and stirring was initiated at 1,000 rpm. Hydrogen was then introduced to adjust the intrinsic viscosity IV (molecular weight) until the pressure inside the polymerization reactor reached 0.00035 MPa. Ethylene and 0.05 mol% 1-butene (comonomer) were then introduced into the polymerization reactor through separate lines until the pressure inside the polymerization reactor reached 0.35 MPa. 5.0 mg of catalyst 1 was then dispersed in 200 mL of dehydrated normal hexane and introduced into the polymerization reactor. A batch polymerization reaction was carried out for 1.0 hour. During the polymerization reaction, the pressure inside the polymerization reactor was maintained by appropriately adding ethylene and comonomer. The polymerization reactor was then opened, and the contents were filtered under reduced pressure to separate and recover the powdery solid component. The resulting solid component was placed in a 68 mm stainless steel beaker and dried at 100°C for 2.5 hours to obtain ultra-high molecular weight polyethylene powder. The yield of ultra-high molecular weight polyethylene powder was 131.6 g, and the catalytic activity (amount of polyethylene obtained per unit catalyst weight) was 26,320 (g-PE / g-catalyst). After removing scale and extremely coarse particles using a sieve with 425 μm openings, the physical properties of the ultra-high molecular weight polyethylene powder were evaluated. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 1. The obtained ultra-high molecular weight polyethylene powder was used to produce high strength fibers by the method described in (11) or (12) above. The evaluation results of the obtained high strength fibers are shown in Table 2.

[0192] [Example 9] A 1.5 L vessel-type polymerization reactor equipped with a stirrer was evacuated, and 500 mL of a mixed solvent (prepared by thoroughly mixing 70% by mass of dehydrated normal hexane and 30% by mass of liquid paraffin) was introduced into the reactor. Next, 0.6 mL of cocatalyst 2 was dispersed in 100 mL of dehydrated normal hexane and introduced into the reactor. The temperature of the polymerization reactor was adjusted to 58 °C, and stirring was initiated at 1,000 rpm. Ethylene gas was then introduced into the reactor to maintain a pressure of 0.4 MPa. 20.0 mg of catalyst 2-2 was then dispersed in 200 mL of dehydrated normal hexane and introduced into the reactor. A batch polymerization reaction was carried out for 0.7 hours. The pressure inside the polymerization reactor was maintained by appropriately introducing additional ethylene gas into the polymerization reactor during the polymerization reaction. The reactor was then opened, and the contents were filtered under reduced pressure to separate and recover the powdery solid component. The resulting solid component was placed in a 68 mm diameter stainless steel beaker and dried at 70°C for 2.0 hours to yield ultra-high molecular weight polyethylene powder. The yield of ultra-high molecular weight polyethylene powder was 98.6 g, and the catalytic activity (amount of polyethylene obtained per unit catalyst weight) was 4930 (g-PE / g-catalyst). After removing scale and extremely coarse particles using a sieve with 425 μm openings, the physical properties of the ultra-high molecular weight polyethylene powder were evaluated. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 2. The obtained ultra-high molecular weight polyethylene powder was used to produce high strength fibers by the method described in (11) or (12) above. The evaluation results of the obtained high strength fibers are shown in Table 2.

[0193] [Example 10] A 1.5 L vessel-type polymerization reactor equipped with a stirrer was evacuated, and 500 mL of a mixed solvent (prepared by thoroughly mixing 50% by mass of dehydrated normal hexane and 50% by mass of liquid paraffin) was introduced into the reactor. Next, 0.6 mL of cocatalyst 2 was dispersed in 100 mL of dehydrated normal hexane and introduced into the reactor. The temperature of the polymerization reactor was adjusted to 50°C, and stirring was initiated at 1,000 rpm. Ethylene gas was then introduced into the reactor to maintain a pressure of 0.4 MPa. 20.0 mg of catalyst 2-2 was then dispersed in 200 mL of dehydrated normal hexane and introduced into the reactor. A batch polymerization reaction was carried out for 1.0 hour. The pressure inside the polymerization reactor was maintained by appropriately introducing additional ethylene gas into the polymerization reactor during the polymerization reaction. The polymerization reactor was then opened, and the contents were filtered under reduced pressure to separate and recover the powdery solid component. The resulting solid component was placed in a 68 mm diameter stainless steel beaker and dried at 65°C for 1.5 hours to yield ultra-high molecular weight polyethylene powder. The yield of ultra-high molecular weight polyethylene powder was 70.4 g, and the catalytic activity (amount of polyethylene obtained per unit catalyst weight) was 3520 (g-PE / g-catalyst). After removing scale and extremely coarse particles using a sieve with 425 μm openings, the physical properties of the ultra-high molecular weight polyethylene powder were evaluated. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 2. The obtained ultra-high molecular weight polyethylene powder was used to produce high strength fibers by the method described in (11) or (12) above. The evaluation results of the obtained high strength fibers are shown in Table 2.

[0194] [Example 11] A 1.5 L vessel-type polymerization reactor equipped with a stirrer was evacuated, and 500 mL of a mixed solvent (prepared by thoroughly mixing 70% by mass of dehydrated normal hexane and 30% by mass of liquid paraffin) was introduced into the reactor. Next, 0.6 mL of cocatalyst 3 was dispersed in 100 mL of dehydrated normal hexane and introduced into the reactor. The temperature of the polymerization reactor was adjusted to 70 °C, and stirring was initiated at 1,000 rpm. Ethylene gas was then introduced into the reactor to maintain a pressure of 0.8 MPa. 20.0 mg of catalyst 3-2 was then dispersed in 200 mL of dehydrated normal hexane and introduced into the reactor. A batch polymerization reaction was carried out for 1.5 hours. The pressure inside the polymerization reactor was maintained by appropriately introducing additional ethylene gas into the polymerization reactor during the polymerization reaction. The reactor was then opened, and the contents were filtered under reduced pressure to separate and recover the powdery solid component. The resulting solid component was placed in a 68 mm diameter stainless steel beaker and dried at 70°C for 2.0 hours to yield ultra-high molecular weight polyethylene powder. The yield of ultra-high molecular weight polyethylene powder was 86.4 g, and the catalytic activity (amount of polyethylene obtained per unit catalyst weight) was 4320 (g-PE / g-catalyst). After removing scale and extremely coarse particles using a sieve with 425 μm openings, the physical properties of the ultra-high molecular weight polyethylene powder were evaluated. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 2. The obtained ultra-high molecular weight polyethylene powder was used to produce high strength fibers by the method described in (11) or (12) above. The evaluation results of the obtained high strength fibers are shown in Table 2.

[0195] [Example 12] Polymerization was carried out by the method described in Example 3, except that a vacuum was created inside a 1.5 L vessel-type polymerization reactor equipped with a stirrer, and 500 mL of a mixed solvent prepared by thoroughly mixing 70% by mass of dehydrated normal hexane and 30% by mass of dibutyl phthalate was introduced into the polymerization reactor beforehand. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 1. Furthermore, a microporous membrane for secondary battery separators was produced using the obtained ultra-high molecular weight polyethylene powder by the method described in (5) or (6) above. The evaluation results of the obtained microporous membrane are shown in Table 1.

[0196] [Example 13] Polymerization was carried out as described in Example 3, except that a vacuum was created inside a 1.5-L vessel-type polymerization reactor equipped with a stirrer, 500 mL of a mixed solvent prepared by thoroughly mixing 50% by mass of dehydrated normal hexane and 50% by mass of liquid paraffin in advance was introduced into the polymerization reactor, and ethylene gas was introduced so that the pressure inside the polymerization reactor became 0.07 MPa. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 1. Furthermore, a microporous membrane for secondary battery separators was produced using the obtained ultra-high molecular weight polyethylene powder by the method described in (5) or (6) above. The evaluation results of the obtained microporous membrane are shown in Table 1.

[0197] [Table 1]

[0198] [Table 2]

[0199] [Comparative Example 1] A 1.5 L vessel-type polymerization reactor equipped with a stirrer was evacuated and 500 mL of dehydrated normal hexane was introduced into the reactor. Next, 0.6 mL of cocatalyst 1 was dispersed in 100 mL of dehydrated normal hexane and introduced into the reactor. The temperature of the polymerization reactor was adjusted to 80 °C, and stirring was initiated at 1,000 rpm. Hydrogen was then introduced to adjust the intrinsic viscosity IV (molecular weight) until the pressure inside the polymerization reactor reached 0.24 MPa. A mixed gas prepared by premixing ethylene with 0.05 mol% 1-butene (comonomer) was then introduced into the polymerization reactor until the pressure inside the polymerization reactor reached 0.4 MPa. Next, 10.0 mg of catalyst 2-1 was dispersed in 200 mL of dehydrated normal hexane and introduced into the polymerization reactor. A batch polymerization reaction was carried out for 1.0 hour. The pressure inside the polymerization reactor was maintained by appropriately introducing additional mixed gas into the polymerization reactor during the polymerization reaction. The polymerization reactor was then opened, and the contents were filtered under reduced pressure to separate and recover the powdery solid component. The resulting solid component was placed in a 68 mm diameter stainless steel beaker and dried at 100°C for 1.0 hour to obtain polyethylene powder. The yield of polyethylene powder was 174.4 g, and the catalytic activity (amount of polyethylene obtained per unit catalyst weight) was 17,440 (g-PE / g-catalyst). After removing scale and extremely coarse particles using a sieve with 425 μm openings, the physical properties of the ultra-high molecular weight polyethylene powder were evaluated. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 3. Using the obtained polyethylene powder, an attempt was made to produce a microporous membrane for a secondary battery separator by the method described in (5) or (6) above, but production was unsuccessful.

[0200] Comparative Example 2 A 1.5 L vessel-type polymerization reactor equipped with a stirrer was evacuated, and a total of 500 mL of 70% by mass dehydrated normal hexane and 30% by mass liquid paraffin was introduced into the polymerization reactor. Next, 0.6 mL of cocatalyst 2 was dispersed in 100 mL of dehydrated normal hexane and introduced into the polymerization reactor. The temperature of the polymerization reactor was adjusted to 40°C, and stirring was initiated at 1,000 rpm. Ethylene gas was then introduced so that the pressure inside the polymerization reactor reached 0.4 MPa. 20.0 mg of catalyst 2-2 was then dispersed in 200 mL of dehydrated normal hexane and introduced into the polymerization reactor. A batch polymerization reaction was carried out for 1.0 hour. The pressure inside the polymerization reactor was maintained by appropriately introducing additional ethylene gas into the polymerization reactor during the polymerization reaction. The polymerization reactor was then opened, and the contents were filtered under reduced pressure to separate and recover the powdery solid component. The resulting solid component was placed in a 68 mm diameter stainless steel beaker and dried at 70°C for 2.5 hours to yield ultra-high molecular weight polyethylene powder. The yield of ultra-high molecular weight polyethylene powder was 93.4 g, and the catalytic activity (amount of polyethylene obtained per unit catalyst weight) was 4670 (g-PE / g-catalyst). After removing scale and extremely coarse particles using a sieve with 425 μm openings, the physical properties of the ultra-high molecular weight polyethylene powder were evaluated. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 4. The obtained ultra-high molecular weight polyethylene powder was used to produce high strength fibers by the method described in (11) or (12) above. The evaluation results of the obtained high strength fibers are shown in Table 4.

[0201] Comparative Example 3 A 1.5 L vessel-type polymerization reactor equipped with a stirrer was evacuated and 500 mL of dehydrated normal hexane was introduced into the reactor. Next, 0.6 mL of cocatalyst 1 was dispersed in 100 mL of dehydrated normal hexane and introduced into the reactor. The temperature of the polymerization reactor was adjusted to 80 °C, and stirring was initiated at 1,000 rpm. Hydrogen was then introduced to adjust the intrinsic viscosity IV (molecular weight) until the pressure inside the polymerization reactor reached 0.0036 MPa, and ethylene gas was then introduced until the pressure inside the polymerization reactor reached 0.4 MPa. 5.0 mg of catalyst 1 was then dispersed in 200 mL of dehydrated normal hexane and introduced into the polymerization reactor. A batch polymerization reaction was carried out for 1.0 hour. The pressure inside the polymerization reactor was maintained by appropriately introducing additional ethylene gas into the polymerization reactor during the polymerization reaction. The polymerization reactor was then opened, and the contents were filtered under reduced pressure to separate and recover the powdery solid component. The resulting solid component was placed in a 68 mm diameter stainless steel beaker and dried at 60°C for 3.0 hours to yield ultra-high molecular weight polyethylene powder. The yield of ultra-high molecular weight polyethylene powder was 136.0 g, and the catalytic activity (amount of polyethylene obtained per unit catalyst weight) was 27,200 (g-PE / g-catalyst). Scale and extremely coarse particles were removed using a sieve with 425 μm openings, and 600 ppm of calcium stearate was added. The physical properties of the ultra-high molecular weight polyethylene powder were then evaluated. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 3. The obtained ultra-high molecular weight polyethylene powder was used to produce a microporous membrane for a secondary battery separator by the method described in (5) or (6) above. The evaluation results of the obtained microporous membrane are shown in Table 3.

[0202] Comparative Example 4 A 1.5 L vessel-type polymerization reactor equipped with a stirrer was evacuated and 500 mL of dehydrated normal hexane was introduced into the reactor. Next, 0.6 mL of cocatalyst 2 dispersed in 100 mL of dehydrated normal hexane was introduced into the reactor, the reactor temperature was adjusted to 50 °C, and stirring was initiated at 1,000 rpm. Ethylene gas was then introduced to maintain the pressure inside the reactor at 0.4 MPa. 20.0 mg of catalyst 2-2 dispersed in 200 mL of dehydrated normal hexane was then introduced into the reactor, and the batch polymerization reaction was carried out for 1.0 hour. The pressure inside the polymerization reactor was maintained by appropriately introducing additional ethylene gas into the reactor during the polymerization reaction. The reactor was then opened, and the contents were filtered under reduced pressure to separate and recover the powdery solid component. The resulting solid component was placed in a 68 mm stainless steel beaker and dried at 65 °C for 1.5 hours to obtain ultra-high molecular weight polyethylene powder. The yield of ultra-high molecular weight polyethylene powder was 79.6 g, and the catalytic activity (amount of polyethylene obtained per unit catalyst weight) was 3980 (g-PE / g-catalyst). After removing scale and extremely coarse particles using a sieve with 425 μm openings, the physical properties of the ultra-high molecular weight polyethylene powder were evaluated. The evaluation results of the ultra-high molecular weight polyethylene powder are shown in Table 4. The obtained ultra-high molecular weight polyethylene powder was used to produce high strength fibers by the method described in (11) or (12) above. The evaluation results of the obtained high strength fibers are shown in Table 4.

[0203] [Table 3]

[0204] [Table 4]

[0205] This application is based on a Japanese patent application (Patent Application No. 2021-159241) filed on September 29, 2021, the contents of which are incorporated herein by reference. [Industrial Applicability]

[0206] The ultra-high molecular weight polyethylene powder of the present invention has excellent moldability when previously swollen at low temperatures, and therefore can provide high-quality molded articles, such as separators for secondary batteries and fibers, and has industrial applicability.

Claims

1. The intrinsic viscosity IV is 1.0 dL / g or more and 33.0 dL / g or less, The average value T of the swelling initiation temperature obtained by the following methods 1 and 2 S is 90°C or higher and 130°C or lower, the standard deviation s of the swelling onset temperatures of powders having particle sizes D10, D50, and D90 is 5°C or less; D90 is 425 μm or less, An ultra-high molecular weight polyethylene powder having a D 90 / D 10 ratio of 1.2 or more and 4.0 or less. [Method 1; D 10 , D 50 and D 90 Measurement method] The particle size of the target ultra-high molecular weight polyethylene powder was measured using a laser particle size distribution analyzer with methanol as a dispersion medium, and a cumulative particle size distribution was created from the small particle size side based on the measurement. The particle sizes at 10%, 50%, and 90% of the cumulative size were designated D 10 , D 50 and D 90 Let's say. [Method 2; Swelling start temperature T 10 , T 50 , T 90 Measurement method and its average value T S Calculation method] Particle diameter is D 10 The swelling start temperature T of the powder is 10 First, the major axis diameter and minor axis diameter (in the plane diagram of a particle observed using an optical microscope, the shortest distance between parallel lines is the minor axis diameter of the particle, and the longest distance between parallel lines in the direction perpendicular to that is the major axis diameter of the particle) are calculated as follows: 10 One particle of ultra-high molecular weight polyethylene powder within a ±10% range is randomly selected while being checked with an optical microscope. One particle of the selected ultra-high molecular weight polyethylene powder (hereinafter also referred to as "measured particle") is placed on a glass slide, and 0.05 mL of liquid paraffin is dripped onto the measured particle using a 1 mL syringe, after which a cover glass is placed on top to sandwich the measured particle. The slide is then placed on a heat stage and heated from room temperature to 150°C under the following heating conditions. The appearance of the measured particle during heating is photographed every 6 seconds using a camera-equipped optical microscope. The circular equivalent diameter of the measured particle is calculated from each of the obtained observation images, and the minimum temperature at which the circular equivalent diameter of the measured particle increases by 1% or more in the temperature range of 80°C to 150°C, based on the circular equivalent diameter of the measured particle at 80°C, is defined as the swelling onset temperature of the measured particle. Measurements are performed at 10 points, and the average value of these measurements is taken as the swelling onset temperature T 10 Let's say. Next, the particle diameter is D 50 The swelling starting temperature T of the ultra-high molecular weight polyethylene powder is 50 , and the particle diameter is D 90 The swelling starting temperature T of the ultra-high molecular weight polyethylene powder is 90 Regarding the swelling starting temperature T 10 Similarly, the major and minor axis diameters are D 50 Ultra-high molecular weight polyethylene powder within the range of ±10%, and the major axis diameter and minor axis diameter are D 90 It is determined using ultra-high molecular weight polyethylene powder within a range of ±10%. Finally, the swelling starting temperature T 10 , T 50 , T 90 The average value of T S is calculated as follows: [Equation 1] (Temperature increase conditions) Heating rate from room temperature to 35°C: 5°C / min Heating rate in the range of 35°C to 80°C: 8°C / min Heating rate in the range of 80°C to 150°C: 5°C / min

2. Particle diameter is D 10 , D 50 and D 90 2. The ultra-high molecular weight polyethylene powder according to claim 1, wherein the standard deviation s of the swelling initiation temperature of the powder is 2.4°C or less.

3. 13 3. The ultra-high molecular weight polyethylene powder according to claim 1, wherein the comonomer content measured by C-NMR is 1.0 mol% or less.

4. 3. The ultra-high molecular weight polyethylene powder according to claim 1, wherein the titanium (Ti) content is 5.0 ppm or less, the aluminum (Al) content is 5.0 ppm or less, and the silicon (Si) content is 100 ppm or less.

5. D 10 The ultra-high molecular weight polyethylene powder according to claim 1 or 2, wherein the particle size is 30 μm or more.

6. A molded article obtained by molding the ultra-high molecular weight polyethylene powder according to claim 1.

7. The molded article according to claim 6 , which is a separator for a secondary battery.

8. The number of defects is less than 90 / m 2 , The film thickness variation is less than ±4.0 μm relative to the average film thickness, The strength converted into basis weight is 60 gf / (g / m 2 ) or more, The heat shrinkage rate is less than 30%. The molded article according to claim 7.

9. A method for producing the molded body according to claim 7, comprising: In the wet method using a solvent, The method comprises the steps of extruding a raw material containing the ultra-high molecular weight polyethylene powder according to claim 1 using an extruder equipped with a T-die, stretching, extracting, and drying, In the extrusion step, the ultra-high molecular weight polyethylene powder and liquid paraffin are pre-impregnated at a temperature 50°C lower than the melting point of the ultra-high molecular weight polyethylene powder.

10. The molded article according to claim 6 , wherein the molded article is a fiber.

11. The molded body is a high-strength fiber, The number of yarn clumps is less than 10 / m, The yarn system irregularity varies by less than ±10 μm from the average yarn diameter, The tensile strength is 20 cN / dtex or more. The molded article according to claim 10.

12. A method for producing the molded body according to claim 10, comprising: The molded body is a high-strength fiber, A method for producing a molded product, comprising the steps of: preparing a slurry liquid by pre-impregnating liquid paraffin with the ultra-high molecular weight polyethylene powder according to claim 1 at a temperature 50°C lower than the melting point of the ultra-high molecular weight polyethylene powder; kneading and spinning the slurry liquid; and heating and drawing the slurry liquid.

13. 2. A method for producing the ultra-high molecular weight polyethylene powder according to claim 1, A step of polymerizing ethylene by mixing a comonomer in ethylene at a gas phase concentration of 0.01 to 0.05 mol % when producing an ethylene polymer; drying the polymerized powder at 100°C or higher; A method for producing an ultra-high molecular weight polyethylene powder having the formula:

14. 2. A method for producing the ultra-high molecular weight polyethylene powder according to claim 1, A method for producing ultra-high molecular weight polyethylene powder, comprising a polymerization step of carrying out polymerization in a state in which 30 to 50 mass % of a plasticizer is added to a polymerization solvent.

15. a removing step of removing the plasticizer from the powder after the polymerization step is completed; and a drying step of reducing the catalytic activity during polymerization to 5000 (g-PE / g-catalyst) or less and drying the polymerized powder at 70°C or less; The method for producing the ultra-high molecular weight polyethylene powder according to claim 14, comprising:

16. The method for producing an ultra-high molecular weight polyethylene powder according to claim 14 or 15, wherein the plasticizer is liquid paraffin.

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