Ultra-high molecular weight polyethylene powder and molded article

Abstract

An ultra-high molecular weight polyethylene powder which has an intrinsic viscosity (IV) of 12.0-35.0 dL / g inclusive and a motility index of 57-73 milliseconds inclusive as determined from the following formula I [motility index] = T [alpha] * R [alpha] / (R [alpha] + R [beta]) + T [beta] * R [beta] / (R [alpha] + R [beta]) (formula I) [in formula I, T [alpha] is the relaxation time (milliseconds) of a low-motility component [alpha], R [beta] is the relaxation time (milliseconds) of the low-motility component [alpha], R [beta] is the relaxation time (milliseconds) of the low-motility component [alpha], and R [beta] is the relaxation time (milliseconds) of the low-motility component [beta]. R [alpha] is the abundance ratio of the component [alpha] having low motility, T [beta] is the relaxation time (milliseconds) of the component [beta] having middle motility, and R [beta] is the abundance ratio of the component [beta] having middle motility. T [alpha], R [alpha], T [beta], and R [beta] are values obtained by approximating a free induction decay curve obtained by the Carr Purcell Meiboom Gill method using pulse NMR to three components, i.e., a component [alpha] having low motility, a component [beta] having middle motility, and a component [gamma] having high motility].

Description

Technical Field

[0001] This invention relates to ultra-high molecular weight polyethylene powder and molded articles. Background Technology

[0002] Polyethylene is used in a wide variety of applications, including membranes, sheets, microporous membranes, fibers, foams, and pipes. The reason for using polyethylene is its ease of melt processing, resulting in molded bodies with high mechanical strength, excellent chemical resistance, and superior rigidity. Ultra-high molecular weight polyethylene (UHMWPE), in particular, has a large molecular weight, resulting in even higher mechanical strength, excellent lubricity and abrasion resistance, as well as superior chemical stability and long-term reliability.

[0003] Even when ultra-high molecular weight polyethylene is melted at temperatures above its melting point, its fluidity is low. Therefore, it is usually processed by adding solvents such as liquid paraffin and decahydronaphthalene to ultra-high molecular weight polyethylene powder to form a slurry.

[0004] From the viewpoint of improving the extrusion processability of ultra-high molecular weight polyethylene and increasing the strength of molded articles, a method such as Patent Document 1 has been disclosed. Patent Document 1 discloses that by adjusting the pore volume and pore size of polyethylene powder with small molecular weight variation and large particle size under specific mixing conditions to an appropriate range, processability is easy and high-strength molded articles can be obtained.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: WO2019 / 187727 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] To improve the tensile processability of ultra-high molecular weight polyethylene (UHMWPE) and obtain high-strength molded parts, it is necessary to fully untangle the molecular chains. When the molecular chains are not fully untangled, the shearing during mixing causes the chains to break, reducing the molecular weight. While this may achieve high orientation, it results in a decrease in strength.

[0010] Patent Document 1 describes a polyethylene powder that focuses on untangling molecular chains by adjusting the pore volume and pore size of the polyethylene powder with large particle size to an appropriate range. However, it does not describe improving the strength of the filament by reducing the amount of entanglement of the polyethylene powder itself, which is independent of the particle size. There is still room for improvement.

[0011] The present invention was made in view of the above circumstances, and its purpose is to obtain high-strength fibers by minimizing the decrease in molecular weight during gel spinning of ultra-high molecular weight polyethylene powder, making it less prone to breakage even when wound at high speed.

[0012] means for solving problems

[0013] In order to solve the above problems, the inventors conducted in-depth research and found that, in particular, by controlling the entanglement (mobility) of ultra-high molecular weight polyethylene powder in liquid paraffin, the above problems can be solved, thus completing the present invention.

[0014] That is, the present invention is as follows.

[0015] [1] An ultra-high molecular weight polyethylene powder, wherein the intrinsic viscosity IV of the ultra-high molecular weight polyethylene powder is above 12.0 dL / g and below 35.0 dL / g. The kinematic index of ultra-high molecular weight polyethylene powder, calculated from the following (Equation I), is greater than 57 milliseconds and less than 73 milliseconds. [Athleticity Index] = Tα × Rα / (Rα + Rβ) + Tβ × Rβ / (Rα + Rβ) (Equation I) In Equation I, Tα is the relaxation time (milliseconds) of the low-motor component α. Rα represents the proportion of the low-motor component α present. Tβ is the relaxation time (milliseconds) of the dynamic component β. Rβ represents the proportion of the component β that is moderately mobile. The values ​​of Tα, Rα, Tβ, and Rβ are obtained by approximating the free induction decay curves obtained using pulsed NMR and the Carr Purcell Meiboom Gill method as three components: a low-move component α, a medium-move component β, and a high-move component γ.

[0016] [2] According to the ultra-high molecular weight polyethylene powder described in [1], wherein the degree of entanglement of the ultra-high molecular weight polyethylene powder, as determined by the following (Formula II), is 0.6 or more and 2.8 or less. [Entanglement degree] = Rβ / Rα (Equation II) [In Formula II, Rβ and Rα are as described in claim 1].

[0017] [3] The ultra-high molecular weight polyethylene powder according to [1] or [2], wherein the ultra-high molecular weight polyethylene powder satisfies the following relationship (Formula III). [Kinematics Index] > -0.2 × [Intrinsic Viscosity IV] + 62 (Equation III).

[0018] [4] The ultra-high molecular weight polyethylene powder according to any one of [1] to [3], wherein, through 13The content of structural units derived from olefins capable of copolymerizing with ethylene in the ultra-high molecular weight polyethylene powder, as determined by C-NMR, is less than 0.1 mol%.

[0019] [5] The ultra-high molecular weight polyethylene powder according to any one of [1] to [4], wherein the D50 of the ultra-high molecular weight polyethylene powder, as determined by a laser diffraction particle size distribution measuring device, is 40 μm or more and 400 μm or less.

[0020] [6] The ultra-high molecular weight polyethylene powder according to any one of [1] to [5], wherein the intrinsic viscosity IV of the ultra-high molecular weight polyethylene powder is 17.0 dL / g or more and 33.0 dL / g or less.

[0021] [7] The ultra-high molecular weight polyethylene powder according to any one of [1] to [6], wherein the motion index of the ultra-high molecular weight polyethylene powder is 64 milliseconds or more and 73 milliseconds or less.

[0022] [8] Ultra-high molecular weight polyethylene powder according to any one of [1] to [7], wherein the content of titanium (Ti) in the ultra-high molecular weight polyethylene powder is less than 10 ppm and the content of aluminum (Al) is less than 10 ppm.

[0023] [9] Ultra-high molecular weight polyethylene powder according to any one of [1] to [8], wherein the ultra-high molecular weight polyethylene powder is used for high-strength fibers.

[0024]

[10] A molded body, wherein the molded body is a molded body of ultra-high molecular weight polyethylene powder as described in any one of [1] to [9].

[0025]

[11] The molded body according to

[10] , wherein the molded body is a fiber.

[0026]

[12] A method for manufacturing a high-strength fiber, wherein the method for manufacturing the high-strength fiber comprises the following steps: In the slurry preparation process, ultra-high molecular weight polyethylene powder and a first liquid paraffin are mixed, and the mixture is stirred at a temperature below the melting point of the ultra-high molecular weight polyethylene powder to obtain a slurry. In the gelation process, the slurry is mixed with a second liquid paraffin at a temperature above 150°C and below 300°C to obtain a gel for precursor fibers at a temperature above 140°C and below 200°C. In the extrusion process, the precursor fiber is extruded using a gel to obtain the precursor fiber. The extraction process includes extracting the first liquid paraffin and the second liquid paraffin from the precursor fiber to obtain a drawing precursor fiber. The raw yarn stretching process includes heating and stretching the raw yarn for stretching. The intrinsic viscosity IV of the ultra-high molecular weight polyethylene powder is above 12.0 dL / g and below 35.0 dL / g. The kinematic index of the ultra-high molecular weight polyethylene powder, calculated by the following formula (I), is greater than 57 milliseconds and less than 73 milliseconds. [Athleticity Index] = Tα × Rα / (Rα + Rβ) + Tβ × Rβ / (Rα + Rβ) (Equation I) In Equation I, Tα is the relaxation time (milliseconds) of the low-motor component α. Rα represents the proportion of the low-motor component α present. Tβ is the relaxation time (milliseconds) of the dynamic component β. Rβ represents the proportion of the component β that is moderately mobile. The values ​​of Tα, Rα, Tβ, and Rβ are obtained by approximating the free induction decay curves obtained using pulsed NMR and the Carr Purcell Meiboom Gill method as three components: a low-move component α, a medium-move component β, and a high-move component γ.

[0027]

[13] The method for manufacturing high-strength fibers according to

[12] includes a compounding step for compounding the precursor fibers with a gel prior to the extrusion step.

[0028]

[14] According to the method for manufacturing high-strength fibers as described in

[12] or

[13] , wherein, in the slurry process, the stirring temperature is above 25°C and below 120°C. In the gelation process, the polyethylene concentration of the gel used for the precursor fiber is 3% by mass or more and 20% by mass or less.

[0029]

[15] The method for manufacturing high-strength fibers according to

[13] or

[14] , wherein in the mixing process, the temperature is above 140°C and below 200°C, the time is above 5 minutes and below 180 minutes, and the rotation speed is above 3 rpm and below 50 rpm.

[0030]

[16] A method for manufacturing high-strength fibers according to any one of

[12] to

[15] , wherein a rapid cooling step is performed after the extrusion step. The time from the extrusion process to the quenching process is 0 seconds or more and 10 seconds or less. The temperature of the rapid cooling process is above 5°C and below 30°C.

[0031]

[17] The method for manufacturing high-strength fiber according to any one of

[12] to

[16] , wherein an extrusion preparation step is provided before the extrusion step. The temperature of the extrusion preparation process is above 140°C and below 200°C. The time for the extrusion preparation process is more than 5 minutes and less than 90 minutes.

[0032]

[18] A method for manufacturing high-strength fiber according to any one of

[12] to

[17] , wherein, in the extrusion process, the extrusion speed is 5 mm / min or more and 20 mm / min or less, the winding speed is 200 mm / min or more and 1600 mm / min or less, the ejection amount is 0.2 g / min or more and 1.5 g / min or less, and the spinneret diameter is 0.8 mm or more and 1.5 mm or less.

[0033]

[19] The method for manufacturing high-strength fibers according to any one of

[12] to

[18] , wherein an extraction solvent is used in the extraction step. The extraction solvent is hexane or dichloromethane. The extraction time is more than 3 hours and less than 24 hours.

[0034]

[20] A method for manufacturing high-strength fibers according to any one of

[12] to

[19] , wherein multi-stage stretching is performed in the raw filament stretching process.

[0035]

[21] The method for manufacturing high-strength fibers according to

[20] , wherein the multi-stage stretching is a two-stage stretching.

[0036]

[22] According to the manufacturing method of high-strength fiber described in

[21] , the secondary stretching includes a primary stretching process and a secondary stretching process. In the single stretching process, the feed speed is 50 mm / min or more and 200 mm / min or less, the winding speed is 1000 mm / min or more and 4000 mm / min or less, and the temperature is 110°C or more and 155°C or less. In the secondary stretching process, the feeding speed is 50 mm / min or more and 200 mm / min or less, the winding speed is 100 mm / min or more and 500 mm / min or less, and the temperature is 130°C or more and 155°C or less.

[0037] Invention Effects

[0038] According to the present invention, an ultra-high molecular weight polyethylene powder can be provided, wherein the ultra-high molecular weight polyethylene powder has a small decrease in molecular weight during compounding, can obtain a uniform gel, and therefore has good tensile properties, and can obtain high-strength fibers. Detailed Implementation

[0039] The following is a detailed description of the method for implementing the present invention (hereinafter also referred to as "this embodiment"). It should be noted that the present invention is not limited to this embodiment, and can be implemented in various modifications within its scope.

[0040] [Ultra-high molecular weight polyethylene powder]

[0041] The intrinsic viscosity IV of the ultra-high molecular weight polyethylene powder (hereinafter also referred to as "polyethylene powder" or "powder") in this embodiment is 12.0 dL / g or more and 35.0 dL / g or less, preferably 17.0 dL / g or more and 33.0 dL / g or less, and more preferably 20.9 dL / g or more and 31.0 dL / g or less.

[0042] It should be noted that the intrinsic viscosity IV in this embodiment refers to the intrinsic viscosity obtained from the specific viscosity of the polymer solution.

[0043] The ultra-high molecular weight polyethylene powder of this embodiment has improved strength when its intrinsic viscosity IV is above the lower limit value mentioned above, and further improved formability when its intrinsic viscosity IV is below the upper limit value mentioned above.

[0044] The ultra-high molecular weight polyethylene powder of this embodiment is preferably a powder containing ethylene homopolymer and / or a copolymer of ethylene and an olefin (hereinafter also referred to as "comonomer") capable of copolymerizing with ethylene (hereinafter also referred to as "ethylene polymer").

[0045] There are no particular restrictions on the olefins that can copolymerize with ethylene. Specifically, examples include: α-olefins with 3 or more but less than 15 carbon atoms, cyclic olefins with 3 or more but less than 15 carbon atoms, and olefins with the formula CH2=CHR. 1 (Here, R) 1 It is at least one comonomer composed of a compound represented by an aryl group having 6 to 12 carbon atoms and a straight-chain, branched, or cyclic diene having 3 or more but 15 or fewer carbon atoms. Preferably, it is an α-olefin having 3 or more but 15 or fewer carbon atoms.

[0046] There are no particular limitations on the α-olefins mentioned above. Examples include: propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetracene, 1-tetradecene, etc.

[0047] The ultra-high molecular weight polyethylene powder in this embodiment passes through 13The comonomer content determined by C-NMR is preferably 0.1 mol% or less, more preferably 0.05 mol% or less, and even more preferably 0.02 mol% or less. When the comonomer content in the ultra-high molecular weight polyethylene powder of this embodiment is within the above range, there is a tendency to suppress decomposition, and there is also a tendency to improve the strength of the molded body obtained by molding the ultra-high molecular weight polyethylene powder. The method for determining the comonomer content is as described in the examples described later.

[0048] The ultra-high molecular weight polyethylene powder used in this embodiment can be, for example, an ultra-high molecular weight polyethylene powder made from ethylene produced using naphtha derived from biomass and ethanol derived from biomass as raw materials. For example, the aforementioned ultra-high molecular weight polyethylene powder derived from biomass can be manufactured by a method of pyrolyzing naphtha derived from biomass as raw material.

[0049] [Intrinsic Viscosity IV]

[0050] The intrinsic viscosity IV of the ultra-high molecular weight polyethylene powder in this embodiment is as described above.

[0051] There are no particular limitations on the method for controlling the intrinsic viscosity IV within the aforementioned range. For example, variations in the polymerization temperature of the reactor during the homopolymerization of ethylene or the copolymerization of ethylene with a copolymerizable olefin can be cited. The intrinsic viscosity IV tends to decrease as the polymerization temperature is set higher, and tends to increase as the polymerization temperature is set lower.

[0052] In addition, there are no particular limitations on other methods for adjusting the intrinsic viscosity IV to the above range. For example, changing the type of organometallic compound used as a cocatalyst when homopolymerizing ethylene or when copolymerizing ethylene with an olefin that can copolymerize.

[0053] In addition, there are no particular limitations on other methods for adjusting the intrinsic viscosity IV to the above range. For example, adding a chain transfer agent when homopolymerizing ethylene or when copolymerizing ethylene with an olefin that can copolymerize it can be listed.

[0054] There are no particular limitations on chain transfer agents; examples include hydrogen, ethylene, and α-olefins. By adding chain transfer agents, the intrinsic viscosity (IV) of the resulting ultra-high molecular weight polyethylene tends to decrease, even at the same polymerization temperature.

[0055] It should be noted that, in this embodiment, the intrinsic viscosity IV can be determined by the method described in the embodiments described later.

[0056] [Kinematics index and entanglement degree of ultra-high molecular weight polyethylene powder]

[0057] As a well-known indicator for inferring the entanglement of molecular chains in polyethylene powder, one example is the evaluation of dynamic viscoelasticity.

[0058] In the evaluation of dynamic viscoelasticity, the degree of entanglement is assessed based on the resin's responsiveness when stress is applied, thus allowing the determination of the overall average degree of entanglement in the resin. However, when simultaneously controlling multiple physical properties such as mechanical properties and processability, it is preferable to treat the various entangled components present in the resin separately. Therefore, using only the average degree of entanglement as an indicator is insufficient. Furthermore, the evaluation of dynamic viscoelasticity typically utilizes compressed molded products for measurement, making it unsuitable for evaluating the entanglement of polyethylene powder.

[0059] Furthermore, ultra-high molecular weight polyethylene powder, as its name suggests, has a very high molecular weight and strong molecular chain entanglement. When the intrinsic viscosity IV, like that of the ultra-high molecular weight polyethylene powder in this embodiment, is 12.0 dL / g or higher, there is a significant tendency to observe strong molecular chain entanglement. When the molecular chain entanglement is too strong, melt processing becomes difficult. Therefore, a solvent is added to the polyethylene powder to form a slurry, which is then molded.

[0060] Therefore, in order to clarify the raw materials suitable for molded articles with well-controlled mechanical properties, molding processability, and other physical properties, the inventors discovered that the kinematic index of the slurry (hereinafter also referred to as the "kinematic index"), calculated based on pulse NMR measurements of polyethylene slurry at 150°C, can be used as an indicator to evaluate the entanglement component of polyethylene powder in a solvent. This can be accurately evaluated by measuring the degree of entanglement of polyethylene powder in liquid paraffin under the <slurry kinematics measurement conditions> described later. Furthermore, it was found that by calculating the degree of entanglement of the slurry (hereinafter also referred to as the "entanglement degree") together with the aforementioned kinematic index, the degree of entanglement of polyethylene powder in liquid paraffin can be evaluated more accurately.

[0061] For pulsed NMR measurements, the Carr Purcell Meiboom Gill method, which is suitable for evaluating the kinematics of polymers (such as rubbery polymers) with active molecular chains, was used.

[0062] The results showed that when the free induction decay curves obtained using pulsed NMR and the Carr Purcell Meiboom Gill method were approximated to three components—a component with low kinematicity α, a component with moderate kinematicity β, and a component with high kinematicity γ—polyethylene powder slurry with relaxation times T and component ratios R satisfying the following kinematic index was surprisingly suitable as a raw material for fibers (e.g., high-strength fibers).

[0063] <Conditions for determining the slurry's mobility>

[0064] Measurement apparatus: Bruker TD-NMR apparatus (model: minispec mq20).

[0065] Heating conditions: Increase the temperature by 10℃ / min and maintain it at 60℃ for 23 minutes; Increase the temperature by 10℃ / min and maintain it at 90℃ for 23 minutes; Increase the temperature by 10℃ / min and maintain it at 105℃ for 23 minutes; Increase the temperature by 10℃ / min and maintain it at 120℃ for 23 minutes; Increase the temperature by 5℃ / minute and maintain it at 130℃ for 26 minutes; Increase the temperature by 5℃ / min and maintain it at 140℃ for 26 minutes; Increase the temperature by 5°C / min and maintain it at 150°C for 10 minutes (then measure the mobility).

[0066] It should be noted that the temperatures mentioned above are values ​​obtained by measuring the internal temperature of the sample using thermocouples. Considering the deviation between the device's set temperature and the sample's target temperature (actual temperature), calibration lines (Equation A) and (Equation B) are constructed and corrected. Decimal values ​​are rounded to the nearest whole number.

[0067] (Under the condition of being above 0℃ and below 100℃) y = 1.0984x + 260.88 (Equation A)

[0068] (When the temperature is greater than 100℃ and less than or equal to 200℃) y = 1.1729x + 252.21 (Equation B)

[0069] x = target temperature (°C), y = set temperature (K)

[0070] Slurry preparation conditions: When the total weight of polyethylene powder and liquid paraffin (liquid paraffin manufactured by MORESCO Co., Ltd. (product name: SMOILP-350P)) was set at 100 parts by weight, 30 parts by weight of polyethylene powder, 70 parts by weight of liquid paraffin, and 1 part by weight of antioxidant (antioxidant manufactured by ADEKA Co., Ltd. (ADK STAB AO-60G)) were mixed. After preparation, an impregnation time of 20 hours was set, and the results were measured.

[0071] The liquid paraffin used in the slurry kinematics test was SMOIL P-350P manufactured by MORESCO Co., Ltd., with the following representative properties: density at 15°C: 0.866 g / cm³. 3 Pour point: -10℃; Kinematic viscosity at 40℃: 68.00 mm 2 / s (cSt), kinematic viscosity at 100℃: 9.188 mm 2 / s (cSt), cycloalkanes analysis: Cn: 30%, Cp: 70%, average molecular weight: 489 g / mol.

[0072] (Motor performance index) = Tα×Rα / (Rα+Rβ)+Tβ×Rβ / (Rα+Rβ)……(Equation I)

[0073] Tα: Relaxation time (milliseconds) of the low-momentum component α.

[0074] Rα: The proportion of the low-motor component α present.

[0075] Tβ: Relaxation time (milliseconds) of the motion-centered component β.

[0076] Rβ: The proportion of the motility-intermediate component β present.

[0077] The specific method for measuring the athletic performance index is described in the examples below.

[0078] Liquid paraffin used in molding processes acts as a plasticizer. Any liquid paraffin that can form a homogeneous solution at a temperature above the melting point of ultra-high molecular weight polyethylene powder when mixed with it is acceptable.

[0079] Furthermore, there are no particular restrictions on the antioxidants used during molding and processing; for example, phenolic compounds or phenolic phosphoric acid compounds are preferred. Specifically, examples include: phenolic antioxidants such as 2,6-di-tert-butyl-4-methylphenol (dibutylhydroxytoluene), octadecyl 3-(4-hydroxy-3,5-di-tert-butylphenyl)propionate, and tetra(methylene(3,5-di-tert-butyl-4-hydroxyhydrogenated cinnamate))methane; phosphorus-containing phenolic antioxidants such as 6-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosphazene; and phosphorus-containing antioxidants such as tetra(2,4-di-tert-butylphenyl) 4,4'-biphenylene diphosphonate, tris(2,4-di-tert-butylphenyl) phosphite, and cyclic neopentanetetramethylbis(2,4-tert-butylphenyl phosphite).

[0080] The low-mobility component α in the polyethylene powder slurry of this embodiment is considered to be a component whose molecular chains are strongly entangled and do not easily dissolve and untangle when dissolved in a solvent, and which is easily subjected to strong shear as a physical cross-linking point during molding and processing.

[0081] In this embodiment, the component β with moderate mobility in the polyethylene powder slurry is considered to correspond to the weakly entangled portion of the dissolved and untied molecular chains, and is a component that is easily untied during the molding process. Furthermore, the stronger the entanglement of each component and the lower its mobility, the shorter the relaxation time T.

[0082] It should be noted that the highly mobile component γ in the polyethylene powder slurry of this embodiment is considered to be equivalent to the end of the polyethylene molecular chain that is not entangled with liquid paraffin.

[0083] The mobility index of a slurry is represented by the proportions of each component and the relaxation time when the polymer dissolves in liquid paraffin, and serves as an indicator for evaluating the overall entanglement and mobility of the molecular chains.

[0084] The ultra-high molecular weight polyethylene powder of this embodiment has a kinematic index of 57 milliseconds or more and 73 milliseconds or less under the slurry kinematics test conditions, preferably 60 or more and 69 or less, and more preferably 64 milliseconds or more and 68 milliseconds or less.

[0085] With a kinematic index of 57 milliseconds or higher at 150°C, the molecular chains exhibit appropriate strong entanglement, reducing stress during molding and thus minimizing molecular weight loss. Furthermore, the molecular chains are smoothly unwound, resulting in fibers that are less prone to breakage even under high-speed stretching.

[0086] On the other hand, with a kinematic index of less than 73 milliseconds at 150°C, the molecular chains have appropriate weak entanglement components and sufficient entanglement points, which uniformly transmit stress during stretching, thus making it easy to obtain high-strength filaments.

[0087] Typically, when the molecular chains are highly entangled, their mobility is low. As a result, the shear rate of the mixture increases, leading to a decrease in molecular weight. Alternatively, during stretching, the molecular chains may not move smoothly, resulting in poor molding processability and unevenness.

[0088] On the other hand, when the polymer has a weak degree of entanglement, the molecular chains are considered to have high mobility, thus exhibiting high tensile strength and orientation, resulting in high-strength filaments. However, due to the lack of sufficient entanglement points, stress cannot be uniformly transmitted, leading to unevenness. This unevenness creates sections with weak mechanical strength, which become the starting point for fracture.

[0089] The polyethylene powder of this embodiment can simultaneously improve the mechanical strength and molding processability of the fiber because the degree of entanglement is well controlled.

[0090] In order to control the flowability index of the 150°C slurry of ultra-high molecular weight polyethylene powder of this embodiment within the above-mentioned range, it is necessary to appropriately reduce the entanglement of the polyethylene powder. As a method to reduce entanglement, there are no particular limitations; it is possible to consider suppressing the formation of entanglement in the early stage of polymerization and obtaining a straight-chain polymer without branches.

[0091] As a method to reduce entanglement in polyethylene powder, suppressing entanglement formation in the early stages of polymerization can be considered. Entanglement formation in the early stages of polymerization mainly results from the entanglement of polymer chains growing near the close proximity of active sites. Therefore, it is believed that reducing the density of active sites on the catalyst surface and increasing the distance between active sites can reduce polymerization-induced entanglement.

[0092] For example, there are methods such as: reducing the density of active sites on the catalyst; using a large-volume co-catalyst whose size is greater than the distance between adjacent active sites on the catalyst as a co-catalyst for polymerization; adding titanium tetrachloride and a specific organomagnesium while loading the active sites onto the support; and using a mixture of two or more co-catalysts for polymerization.

[0093] Specifically, one method for reducing the density of active sites on a catalyst is to reduce the amount of titanium loaded on the catalyst by adjusting the molar ratio of the raw materials during synthesis. The molar ratio of titanium to magnesium atoms in the support (Ti / Mg) is preferably 1 / 4 or less, more preferably 1 / 8 or less, even more preferably 1 / 16 or less, and even more preferably 1 / 32 or less. Another method is to release excess titanium compounds by surface treatment with organoaluminum after loading titanium onto the support.

[0094] Titanium tetrachloride is known to sometimes adopt an aggregated structure on a support, where polymer chains grow simultaneously with entanglement from the aggregated active sites. By reducing the density of active sites on the catalyst surface, the number of active sites adopting an aggregated structure can be reduced, thereby reducing entanglement in the early stages of polymerization.

[0095] Alternatively, a large co-catalyst, whose size is greater than the distance between adjacent catalytic active sites, can be used as a co-catalyst for polymerization. Due to the steric hindrance of the large co-catalyst, active sites located closer to the co-catalyst are not activated, and the apparent distance between active sites participating in polymerization becomes wider. Therefore, the polymer chains grown during polymerization are less prone to entanglement, resulting in polyethylene powder with less entanglement.

[0096] Furthermore, the inventors conducted repeated and in-depth studies and discovered that polyethylene powder with less entanglement can also be obtained by using organomagnesium to induce a vigorous reaction when loading active sites onto a support. The rationale for obtaining polyethylene powder with less entanglement using the above method is not yet determined, but it is believed that when titanium tetrachloride and highly reactive organomagnesium are added simultaneously, the vigorous reaction results in the formation of catalyst particles not on the support surface, but in the solvent. Each catalyst particle is loaded onto the support in an independent state, thereby widening the distance between active sites.

[0097] For example, the organic magnesium can be a mixture of dihydromagnesium and trihydroaluminum, preferably with a higher proportion of dihydromagnesium than trihydroaluminum.

[0098] Under the above-described slurry mobility test conditions, the entanglement degree of the ultra-high molecular weight polyethylene powder obtained by the following (Formula II) in this embodiment is 0.6 or more and 2.8 or less, preferably 1.0 or more and 2.7 or less, and more preferably 1.2 or more and 2.6 or less.

[0099] (Degree of entanglement) = Rβ / Rα……(Equation II)

[0100] As mentioned above, Rα and Rβ in (Equation II) represent the proportions of the component α with low mobility and Rβ and the proportions of the component β with moderate mobility, respectively.

[0101] Rα is preferably 9 or more and 24 or less, more preferably 10 or more and 23 or less.

[0102] Rβ is preferably 12 or more and 27 or less, more preferably 13 or more and 26 or less.

[0103] Within the aforementioned ranges of Rα and Rβ, there is a tendency to achieve a good balance of entanglement points, resulting in excellent tensile workability and strength.

[0104] Entanglement is represented by the proportion of the low-moveability component α and the intermediate-moveability component β in liquid paraffin, indicating the number of entanglement points that act like physical cross-linking points that bind molecular chains.

[0105] With an entanglement degree of 0.6 or higher for ultra-high molecular weight polyethylene powder slurry, the number of entanglement points will not become excessive. Even if the polymer concentration is reduced and no mixing is performed, sufficient lamellar crystals can be obtained. Therefore, there is a tendency for the tensile properties to become better and the filaments to be less prone to breakage during gel spinning.

[0106] Furthermore, by having a slurry entanglement degree of 2.8 or less, there are sufficient entanglement points to bear the transmission of tensile stress, thus enabling uniform stress transmission, promoting molecular chain orientation, allowing for stretching at higher ratios, and tending to produce higher strength filaments.

[0107] As a method for controlling the entanglement degree of the 150°C slurry of the ultra-high molecular weight polyethylene powder of this embodiment within the above-mentioned range, a method of polymerizing to obtain a straight-chain polymer without branches can be considered. Without branches, the molecular chains become easier to slide, allowing the entanglement generated during polymerization to dissolve and unravel during the dissolution process, resulting in a polyethylene powder with low entanglement degree in liquid paraffin.

[0108] Specifically, one method involves using a mixture of two or more cocatalysts as the cocatalyst for polymerization. It is known that macromonomers with terminal double bonds are typically generated through β-hydrogen desorption, a chain transfer reaction. These macromonomers are incorporated into the molecular chain during polymerization, thus becoming long branches, which hinder chain unwinding and increase entanglement. Therefore, if using a mixture of two or more cocatalysts as the cocatalyst can promote chain transfer and suppress branching, polyethylene powder with less entanglement during dissolution can be obtained.

[0109] Generally, as the molecular weight of ultra-high molecular weight polyethylene powder increases, entanglement also becomes stronger. This relationship is significant in the molecular weight region where the intrinsic viscosity is less than 12.0 dL / g. Above 12.0 dL / g, the reduction in mobility begins to reach its upper limit, but a relationship can still be established between intrinsic viscosity and the mobility index.

[0110] The ultra-high molecular weight polyethylene powder of this embodiment preferably satisfies the following (Formula III), more preferably satisfies the following (Formula III-A), and even more preferably satisfies the following (Formula III-B).

[0111] [Kinematics Index] > -0.2 × [Intrinsic Viscosity IV] + 62 (Equation III)

[0112] [Kinematics Index] > -0.2 × [Intrinsic Viscosity IV] + 65 (Equation III-A)

[0113] [Kinematics Index] > -0.2 × [Intrinsic Viscosity IV] + 69 (Equation III-B)

[0114] [Titanium and aluminum content in ultra-high molecular weight polyethylene powder]

[0115] The titanium (Ti) content in the ultra-high molecular weight polyethylene powder of this embodiment is preferably 10 ppm or less, more preferably 0 ppm or more and 8 ppm or less, and even more preferably 0 ppm or more and 5 ppm or less. Furthermore, the aluminum (Al) content in the ultra-high molecular weight polyethylene powder of this embodiment is preferably 10 ppm or less, more preferably 0 ppm or more and 8 ppm or less, and even more preferably 0 ppm or more and 5 ppm or less.

[0116] In the ultra-high molecular weight polyethylene powder of this embodiment, by adjusting the content of titanium and aluminum to such a range, the amount of metals leached into the liquid can be reduced. For example, it tends to suppress filtrate contamination in filter applications and improve the safety of medical fibers used in living organisms.

[0117] It should be noted that polyethylene deterioration is typically caused by a high amount of metals from catalyst residues remaining in the ultra-high molecular weight polyethylene powder. It should also be noted that the Ti and Al content in the ultra-high molecular weight polyethylene powder can be controlled by the yield of ethylene homopolymer or ethylene-based polymer per unit of catalyst. The yield of the ethylene homopolymer or ethylene-based polymer can be controlled by the polymerization temperature, polymerization pressure, and slurry concentration of the reactor during manufacturing. That is, there are no particular limitations on improving the yield of the ethylene homopolymer or ethylene-based polymer used in this embodiment; for example, increasing the polymerization temperature, increasing the polymerization pressure, and / or increasing the slurry concentration can be listed. As other methods, the aluminum content can also be controlled by changing the catalyst composition, selecting the type of co-catalyst component, reducing the concentration of the co-catalyst component, or cleaning the ethylene homopolymer or ethylene-based polymer with acid or alkali during polymerization to obtain the ethylene homopolymer or ethylene-based polymer. It should be noted that in this embodiment, the Ti and Al content can be determined by the methods described in the examples described later.

[0118] [Average Particle Size D50]

[0119] The average particle size D50 of the polyethylene powder in this embodiment, as measured by a laser particle size analyzer, is preferably 40 μm or more and 400 μm or less, more preferably 50 μm or more and 350 μm or less, and even more preferably 60 μm or more and 300 μm or less.

[0120] The polyethylene powder of this embodiment has an average particle size D50 of 40 μm or more, which tends to have better processability and fewer problems in the molding process. With an average particle size D50 of 400 μm or less, it has better meltability in solvents (e.g., liquid paraffin), and can obtain gels with more uniform molecular chain distribution and high orientation, thus tending to manufacture high-strength fibers with excellent mechanical strength.

[0121] There are no particular limitations on methods for controlling the average particle size D50 within the aforementioned range. For example, methods include appropriately adjusting the conditions within the polymerization system (polymerization temperature, ethylene pressure, etc.). Specifically, increasing the polymerization temperature and / or polymerization pressure can be cited as examples.

[0122] It should be noted that, in this embodiment, D50 can be obtained by the method described in the embodiments described later.

[0123] [catalyst]

[0124] There are no particular limitations on the catalyst used in the manufacture of the polyethylene powder in this embodiment; for example, a conventional Ziegler-Natta catalyst can be cited. A preferred Ziegler-Natta catalyst is the catalyst for olefin polymerization described below, which comprises a solid catalyst [A] and an organometallic compound component [B], wherein the solid catalyst [A] is manufactured by reacting an organomagnesium compound (hereinafter also referred to as "(A-1)") soluble in an inert hydrocarbon solvent, represented by Formula 1, with a titanium compound (hereinafter also referred to as "(A-2)") represented by Formula 2.

[0125] (A-1): (M) 1 ) α (Mg) β (R) 2 ) a (R) 3 ) b (Y) 1 ) c ...Equation 1

[0126] (In Equation 1, M) 1 R represents a metallic atom belonging to the group consisting of Groups 12, 13, and 14 of the periodic table. 2 and R 3 Y is a hydrocarbon group with 2 or more carbon atoms and less than 20 carbon atoms. 1 Hydroxyl group, silyl group, allyl group, amino group, amide group, -N=CR 4 ,R 5 -SR 6 (Here, R) 4 R 5 and R 6 This indicates a hydrocarbon group with 1 or more but less than 20 carbon atoms. When c is 2, Y... 1 (These can be different from each other) any of the β-keto acid residues, where α, β, a, b, and c are real numbers satisfying 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 (where n represents M) 1 (valence).

[0127] (A-2): Ti(OR) 7 ) d X 1 （4-d） ...Equation 2

[0128] (In Equation 2, d is a real number greater than 0 and less than 4, R) 7 For hydrocarbon groups with 1 or more carbon atoms and less than 20, X 1(These are halogen atoms.)

[0129] It should be noted that there are no particular restrictions on the inert hydrocarbon solvent used in the reaction of (A-1) and (A-2). Specifically, 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.

[0130] First, let's explain (A-1). (A-1) is represented as a complex of organomagnesium soluble in inert hydrocarbon solvents, encompassing all dihydromagnesium compounds and their complexes with other metal compounds. The relationship between the symbols α, β, a, b, and c, nα + 2β = a + b + c, represents the valence of the metal atom and the stoichiometry of the substituents.

[0131] In Equation 1, as R 2 and R 3 The hydrocarbon group represented has 2 or more but less than 20 carbon atoms, and is not particularly limited. Specifically, it is an alkyl, cycloalkyl, or aryl group, such as ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, cyclohexyl, phenyl, etc. Alkyl groups are preferred. When α > 0, M is the metal atom. 1 Metal atoms belonging to groups 12, 13, and 14 of the periodic table can be used, such as zinc, boron, and aluminum. Among them, aluminum and zinc are preferred.

[0132] Magnesium relative to metal atom M 1 The ratio β / α is not particularly limited, but is preferably 0.1 or more and 30 or less, more preferably 0.5 or more and 10 or less. Furthermore, when using a specified organomagnesium compound with α=0, for example in R... 2 In the case of 1-methylpropyl or similar compounds, which are soluble in inert hydrocarbon solvents, such compounds also produce preferred results in this embodiment. In Formula 1, R is recommended when α=0. 2 R 3 It satisfies any one of the three groups (1), (2), and (3) shown below.

[0133] Group (1): R 2 R 3 At least one of them is a secondary or tertiary alkyl group having 4 or more but less than 6 carbon atoms, preferably R. 2 R 3 All of them are alkyl groups with 4 or more but less than 6 carbon atoms, and at least one of them is a secondary or tertiary alkyl group.

[0134] Group (2): R 2 and R 3 Alkyl groups with different numbers of carbon atoms are preferred, R.2 R is an alkyl group with 2 or 3 carbon atoms. 3 It is an alkyl group with 4 or more carbon atoms.

[0135] Group (3): R 2 R 3 At least one of them is a hydrocarbon group having 6 or more carbon atoms, preferably R. 2 R 3 It contains alkyl groups with a total number of carbon atoms of 12 or more.

[0136] These groups are specifically shown below. In group (1), secondary or tertiary alkyl groups having 4 or more but less than 6 carbon atoms are, for example, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, 2-methylbutyl, 2-ethylpropyl, 2,2-dimethylpropyl, 2-methylpentyl, 2-ethylbutyl, 2,2-dimethylbutyl, 2-methyl-2-ethylpropyl, etc. Among these, 1-methylpropyl is particularly preferred.

[0137] In addition, in group (2), alkyl groups having 2 or 3 carbon atoms can be exemplified by, for example, ethyl, 1-methylethyl, propyl, etc. Ethyl is particularly preferred. In addition, alkyl groups having 4 or more carbon atoms are not particularly limited, and can be exemplified by, for example, butyl, pentyl, hexyl, heptyl, octyl, etc. Butyl and hexyl are particularly preferred.

[0138] Furthermore, in group (3), there are no particular restrictions on the hydrocarbon group having 6 or more carbon atoms. Specifically, examples include: hexyl, heptyl, octyl, nonyl, decyl, phenyl, 2-naphthyl, etc. Among the hydrocarbon groups, alkyl groups are preferred, and among the alkyl groups, hexyl and octyl are particularly preferred.

[0139] Generally, as the number of carbon atoms in an alkyl group increases, it tends to dissolve more readily in inert hydrocarbon solvents, but the viscosity of the solution tends to increase. Therefore, from an operational perspective, it is preferable to use moderately long-chain alkyl groups. It should be noted that the above-mentioned organomagnesium compounds can be used after dilution with inert hydrocarbon solvents, and can be used without problems even if the solution contains or contains trace amounts of Lewis basic compounds such as ethers, esters, and amines.

[0140] Next, for Y 1 Explanation is provided. In Equation 1, Y 1 Hydroxyl group, silyl group, allyl group, amino group, amide group, -N=CR 4 ,R 5 -SR 6 (Here, R) 4 R 5 and R 6Each can be independently represented by a hydrocarbon group having 2 or more carbon atoms and less than 20 carbon atoms, or any of the following: a β-keto acid residue.

[0141] In Equation 1, as R 4 R 5 and R 6 The hydrocarbon group represented is preferably an alkyl or aryl group with 1 or more but less than 12 carbon atoms, and particularly preferably an alkyl or aryl group with 3 or more but less than 10 carbon atoms. There are no particular limitations, and 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, etc. Butyl, 1-methylpropyl, 2-methylpentyl, and 2-ethylhexyl are particularly preferred.

[0142] Additionally, in Equation 1, Y 1 Preferably, the hydroxyl group or silanoxy group is used. There are no particular limitations on the hydroxyl group, but specifically, 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 are preferred. More preferably, butoxy, 1-methylpropoxy, 2-methylpentoxy, and 2-ethylhexoxy are used. There are no particular limitations on the silanoxy group, but specifically, dimethylhydrosilanoxy, ethylhydromethylsilanoxy, diethylhydrosilanoxy, trimethylsilanoxy, ethyldimethylsilanoxy, diethylmethylsilanoxy, triethylsilanoxy, etc., are preferred. More preferably, it is hydrogen dimethylsiloxy, ethyl hydrogen methylsiloxy, diethyl hydrogen methylsiloxy, or trimethylsiloxy.

[0143] In this embodiment, the synthesis method of (A-1) is not particularly limited. For example, it can be synthesized by making it belong to the formula R. 2 MgX 1 Sum of R 2 Mg(R) 2 For the meaning described above, X 1 Organomagnesium compounds consisting of halogen atoms (groups of halogen atoms) and those belonging to the group of formula M 1 R 3 n and M 1 R 3 （n-1） H(M) 1 and R 3For the above meaning, n represents M 1 Organometallic compounds of the group consisting of (the oxidation states of the compounds) are reacted in an inert hydrocarbon solvent at a temperature above 25°C and below 150°C, and then, if necessary, reacted with a compound of formula Y. 1 -H(Y) 1 The reaction of compounds (as defined above) or the reaction of compounds having the characteristics of Y 1 The synthesis is achieved by reacting organomagnesia compounds and / or organoaluminum compounds with the indicated functional groups. Specifically, the organomagnesia compound, soluble in an inert hydrocarbon solvent, reacts with a compound of formula Y... 1 When a compound represented by -H reacts, there are no particular restrictions on the order of the reactions. For example, an organomagnesium compound can be reacted by adding a compound of formula Y. 1 -H represents the method of compounds, in the formula Y 1 -H indicates any one of the methods of adding an organomagnesium compound to the compound, or adding both simultaneously.

[0144] In this embodiment, Y in (A-1) 1 The molar composition ratio c / (α+β) relative to all metal atoms is 0 ≤ c / (α+β) ≤ 2, preferably 0 ≤ c / (α+β) < 1. (This is achieved through Y...) 1 When the molar ratio of all metal atoms is less than 2, there is a tendency for increased reactivity of (A-1) and (A-2).

[0145] Next, (A-2) will be explained. (A-2) is a titanium compound represented by Formula 2.

[0146] (A-2): Ti(OR) 7 ) d X 1 （4-d） ...Equation 2

[0147] (In Equation 2, d is a real number greater than 0 and less than 4, R) 7 For hydrocarbon groups with 1 or more carbon atoms and less than 20, X 1 (These are halogen atoms.)

[0148] In Equation 2 above, d is preferably 0 or more and 1 or less, more preferably 0. Furthermore, in Equation 2, as a function of R... 7 The hydrocarbon group represented is not particularly limited, but examples include: aliphatic hydrocarbon groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, 2-ethylhexyl, heptyl, octyl, decyl, and aryl; alicyclic hydrocarbon groups such as cyclohexyl, 2-methylcyclohexyl, and cyclopentyl; and aromatic hydrocarbon groups such as phenyl and naphthyl. Aliphatic hydrocarbon groups are preferred. As a component of X... 1The halogen atom represented can be, for example, chlorine, bromine, or iodine. Chlorine is preferred. In this embodiment, (A-2) is particularly preferred to be titanium tetrachloride. In this embodiment, two or more compounds selected from the above-mentioned compounds can be used in combination.

[0149] Next, the reaction between (A-1) and (A-2) will be described. This reaction is preferably carried out in an inert hydrocarbon solvent, and more preferably in an aliphatic hydrocarbon solvent such as hexane or heptane. The molar ratio of (A-1) to (A-2) in this reaction is not particularly limited, but the molar ratio of Ti atoms in (A-2) to Mg atoms in (A-1) (Ti / Mg) is preferably 0.1 or more and 10 or less, more preferably 0.3 or more and 3 or less. The reaction temperature is not particularly limited, but it is preferably carried out in a range of -80°C to 150°C, and more preferably in a range of -40°C to 100°C. The order of addition of (A-1) and (A-2) is not particularly limited; it can be carried out by adding (A-2) after (A-1), adding (A-1) after (A-2), or adding (A-1) and (A-2) simultaneously, with the method of adding (A-1) and (A-2) simultaneously being preferred. In this embodiment, the solid catalyst [A] obtained by the above reaction is used in the form of a slurry solution using an inert hydrocarbon solvent.

[0150] As another example of the Ziegler-Natta catalyst used in this embodiment, the following olefin polymerization catalyst is preferred, which comprises a solid catalyst [C] and an organometallic compound component [B]. The solid catalyst [C] is manufactured by loading an organomagnesium compound (hereinafter also referred to as "(C-1)") soluble in an inert hydrocarbon solvent, represented by Formula 3, and a titanium compound (hereinafter also referred to as "(C-5)") soluble in an inert hydrocarbon solvent, represented by Formula 5, onto a support (hereinafter also referred to as "(C-3)") prepared by reacting an organomagnesium compound (hereinafter also referred to as "(C-1)") soluble in an inert hydrocarbon solvent, represented by Formula 4, with a chlorinating agent (hereinafter also referred to as "(C-2)") represented by Formula 4.

[0151] (C-1): (M) 2 ) γ (Mg) δ (R) 8 ) e (R) 9 ) f (OR) 10 ) g ...Equation 3

[0152] (In Equation 3, M) 2 R represents a metallic atom belonging to the group consisting of Groups 12, 13, and 14 of the periodic table. 8 R9 and R 10 Each of these is a hydrocarbon group with 2 or more carbon atoms and less than 20 carbon atoms. 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 (where k represents M). 2 The valence of the compound.

[0153] (C-2): H h SiCl i R 11 （4-（h+i）） ...Formula 4

[0154] (In Equation 4, R) 11 For hydrocarbon groups with 1 or more but less than 12 carbon atoms, h and i are real numbers that satisfy the following relationship: 0 < h, 0 < i, 0 < h + i ≤ 4.

[0155] (C-4): (M) 1 ) α (Mg) β (R) 2 ) a (R) 3 ) b Y 1 c ...Formula 5

[0156] (In Equation 5, M) 1 R represents a metallic atom belonging to the group consisting of Groups 12, 13, and 14 of the periodic table. 2 and R 3 Y is a hydrocarbon group with 2 or more carbon atoms and less than 20 carbon atoms. 1 Hydroxyl group, silyl group, allyl group, amino group, amide group, -N=CR 4 ,R 5 -SR 6 (Here, R) 4 R 5 and R 6 This indicates a hydrocarbon group with 1 or more but less than 20 carbon atoms. When c is 2, Y... 1 (These can be different from each other) any of the β-keto acid residues, where α, β, a, b, and c are real numbers satisfying 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 (where n represents M) 1 (valence).

[0157] (C-5): Ti(OR) 7 ) d X 1（4-d） ...Formula 6

[0158] (In Equation 6, d is a real number greater than 0 and less than 4, R) 7 For hydrocarbon groups with 1 or more carbon atoms and less than 20, X 1 (These are halogen atoms.)

[0159] First, let's explain (C-1). Although (C-1) is represented as a complex of organomagnesium soluble in inert hydrocarbon solvents, it encompasses all dihydromagnesium compounds and their complexes with other metal compounds. The relationship between the symbols γ, δ, e, f, and g in Equation 3, kγ+2δ=e+f+g, represents the valence of the metal atom and the stoichiometry of the substituents.

[0160] In equation 3 above, R 8 Or R 9 The hydrocarbon group represented is not particularly limited, but specifically, each can be alkyl, cycloalkyl, or aryl, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, cyclohexyl, phenyl, etc. Among these, R is preferred. 8 and R 9 Each is an alkyl group. In the case of α > 0, it acts as a metal atom M. 2 Metal atoms belonging to groups 12, 13, and 14 of the periodic table can be used, such as zinc, boron, and aluminum. Among them, aluminum and zinc are particularly preferred.

[0161] Magnesium relative to metal atom M 2 The ratio δ / γ is not particularly limited, but is preferably 0.1 or more and 30 or less, more preferably 0.5 or more and 10 or less. Additionally, when using a specified organomagnesium compound with γ=0, for example in R... 8 In the case of 1-methylpropyl or similar compounds, which are soluble in inert hydrocarbon solvents, such compounds also produce preferred results in this embodiment. In Formula 3, R is recommended when γ=0. 8 R 9 It is any one of the three groups (1), (2), and (3) shown below.

[0162] Group (1): R 8 R 9 At least one of them is a secondary or tertiary alkyl group having 4 or more but less than 6 carbon atoms, preferably R. 8 R 9 All of them have 4 or more but less than 6 carbon atoms, and at least one of them is a secondary alkyl or tertiary alkyl group.

[0163] Group (2): R 8 and R 9Alkyl groups with different numbers of carbon atoms are preferred, R. 8 R is an alkyl group with 2 or 3 carbon atoms. 9 It is an alkyl group with 4 or more carbon atoms.

[0164] Group (3): R 8 R 9 At least one of them is a hydrocarbon group having 6 or more carbon atoms, preferably R. 8 R 9 It contains alkyl groups with a total number of carbon atoms of 12 or more.

[0165] Hereinafter, these groups are specifically shown. In group (1), secondary or tertiary alkyl groups having 4 or more and 6 or fewer carbon atoms can be used, for example, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, 2-methylbutyl, 2-ethylpropyl, 2,2-dimethylpropyl, 2-methylpentyl, 2-ethylbutyl, 2,2-dimethylbutyl, 2-methyl-2-ethylpropyl, etc. Among these, 1-methylpropyl is particularly preferred.

[0166] In addition, in group (2), alkyl groups having 2 or 3 carbon atoms can be exemplified by, for example, ethyl, 1-methylethyl, propyl, etc. Among these, ethyl is particularly preferred. Furthermore, there are no particular restrictions on alkyl groups having 4 or more carbon atoms; specifically, examples include, butyl, pentyl, hexyl, heptyl, octyl, etc. Among these, butyl and hexyl are particularly preferred.

[0167] Furthermore, in group (3), there are no particular restrictions on the hydrocarbon group having 6 or more carbon atoms. Specifically, examples include: hexyl, heptyl, octyl, nonyl, decyl, phenyl, 2-naphthyl, etc. Among the hydrocarbon groups, alkyl groups are preferred, and among the alkyl groups, hexyl and octyl are particularly preferred.

[0168] Generally, as the number of carbon atoms in an alkyl group increases, it tends to dissolve more readily in inert hydrocarbon solvents, and the viscosity of the solution tends to increase. Therefore, from an operational perspective, it is preferable to use moderately long-chain alkyl groups. It should be noted that the above-mentioned organomagnesium compounds are used in the form of inert hydrocarbon solutions, and can be used without problems even if trace amounts of Lewis basic compounds such as ethers, esters, and amines are present or remain in the solution.

[0169] Next, the hydroxyl group (OR) 10 This will be explained by R. 10 The hydrocarbon group represented is preferably an alkyl or aryl group with 1 or more and 12 or fewer carbon atoms, and particularly preferably an alkyl or aryl group with 3 or more and 10 or fewer carbon atoms. As R 10There are no particular restrictions, but 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, etc. Butyl, 1-methylpropyl, 2-methylpentyl, and 2-ethylhexyl are particularly preferred.

[0170] In this embodiment, the synthesis method of (C-1) is not particularly limited, but it is preferable to use a method belonging to formula R. 8 MgX 1 Sum of R 8 Mg(R) 8 For the meaning described above, X 1 Organomagnesium compounds consisting of halogen atoms (groups of halogen atoms) and those belonging to the group of formula M 2 R 9 k Japanese M 2 R 9 （k-1） H(M) 2 R 9 Organometallic compounds consisting of R (and k as defined above) are reacted in an inert hydrocarbon solvent at a temperature above 25°C and below 150°C, and then, if necessary, reacted with an organometallic compound having R 9 (R) 9 Alcohols with a hydrocarbon group (as defined above) or those soluble in inert hydrocarbon solvents and containing a hydrocarbon group represented by R. 9 A method for reacting hydrocarbon-based magnesium hydroxyl compounds and / or hydrocarbon-based aluminum hydroxyl compounds.

[0171] In the case of reacting an organomaglenoid soluble in an inert hydrocarbon solvent with an alcohol, there is no particular restriction on the order of the reaction. Any method can be used, such as adding the alcohol to the organomaglenoid, adding the organomaglenoid to the alcohol, or adding both simultaneously. In this embodiment, there is no particular restriction on the reaction ratio of the organomaglenoid soluble in the inert hydrocarbon solvent to the alcohol. The result of the reaction is that the molar ratio of the hydroxyl group to all metal atoms in the obtained organomaglenoid containing hydroxyl groups, g / (γ+δ), is 0 ≤ g / (γ+δ) ≤ 2, preferably 0 ≤ g / (γ+δ) < 1.

[0172] Next, (C-2) will be explained. (C-2) is a silicon chloride compound represented by Formula 4 that has at least one Si-H bond.

[0173] (C-2): H h SiCl i R 11（4-（h+i）） ...Formula 4

[0174] (In Equation 4, R) 11 For hydrocarbon groups with 1 or more but less than 12 carbon atoms, h and i are real numbers that satisfy the following relationship: 0 < h, 0 < i, 0 < h + i ≤ 4.

[0175] In Equation 4, R 11 The hydrocarbon group represented is not particularly limited. Specifically, it can be an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group. Examples include: methyl, ethyl, propyl, 1-methylethyl, butyl, pentyl, hexyl, octyl, decyl, cyclohexyl, phenyl, etc. Preferably, it is an alkyl group with 1 or more and 10 or less carbon atoms, and more preferably, it is an alkyl group with 1 or more and 3 or less carbon atoms, such as methyl, ethyl, propyl, 1-methylethyl, etc. Furthermore, h and i are numbers greater than 0 that satisfy the relationship h+i≤4, and preferably i is 2 or more and 3 or less.

[0176] There are no particular limitations on these compounds; specifically, 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 H7), HSiCl2(CH2CH=CH2), H2SiCl(CH3), H2SiCl(C2H5), HSiCl(CH3)2, HSiCl(C2H5)2, HSiCl(CH3)(2-C3H7), HSiCl(CH3)(C6H5), HSiCl(C6H5)2, etc. Silicon chloride compounds containing these compounds or mixtures of two or more selected from these compounds can be used. Among these, HSiCl3, HSiCl2CH3, HSiCl(CH3)2, and HSiCl2(C3H7) are preferred, and HSiCl3 and HSiCl2CH3 are more preferred.

[0177] Next, the reaction between (C-1) and (C-2) will be described. During the reaction, it is preferable to pre-treat (C-2) using an inert hydrocarbon solvent; a chlorinated hydrocarbon such as 1,2-dichloroethane, o-dichlorobenzene, or dichloromethane; an ether medium such as diethyl ether or tetrahydrofuran; or a mixture thereof, after dilution. Among these, an inert hydrocarbon solvent is more preferred from the perspective of catalyst performance. The reaction ratio of (C-1) to (C-2) is not particularly limited, but the amount of silicon atoms in (C-2) is preferably 0.01 mol or more and 100 mol or less relative to 1 mole of magnesium atoms contained in (C-1), more preferably 0.1 mol or more and 10 mol or less.

[0178] There are no particular limitations on the reaction method between (C-1) and (C-2). Any of the following methods can be used: adding (C-1) and (C-2) simultaneously to the reactor and allowing them to react at the same time; adding (C-2) to the reactor beforehand and then adding (C-1); or adding (C-1) to the reactor beforehand and then adding (C-2). Preferably, the method of adding (C-2) to the reactor beforehand and then adding (C-1) is used. The carrier (C-3) obtained by the above reaction is preferably thoroughly washed with an inert hydrocarbon solvent after separation by filtration or decantation to remove unreacted substances or byproducts.

[0179] There are no particular limitations on the reaction temperature of (C-1) and (C-2), but it 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 the method of simultaneously introducing (C-1) and (C-2) into the reactor and allowing them to react simultaneously, it is preferable to pre-adjust the reactor temperature to a predetermined temperature, and then adjust the reactor temperature to the predetermined temperature while simultaneously adding the compound, thereby adjusting the reaction temperature to the predetermined temperature. In the method of introducing (C-1) into the reactor after pre-adding (C-2), it is preferable to adjust the temperature of the reactor containing the silicon chloride compound to a predetermined temperature, and then adjust the reactor temperature to the predetermined temperature while simultaneously introducing the organomagnesium compound, thereby adjusting the reaction temperature to the predetermined temperature. In the method of introducing (C-2) into the reactor after (C-1) has been pre-added to the reactor, it is preferable to adjust the temperature of the reactor with (C-1) added to it to a specified temperature, and adjust the temperature inside the reactor to the specified temperature at the same time as (C-2) is introduced into the reactor, thereby adjusting the reaction temperature to the specified temperature.

[0180] Next, the organomagnesium compound (C-4) will be described. As (C-4), the compound represented by Formula 5 (C-4) above is preferred.

[0181] (C-4): (M) 1 ) α (Mg) β (R) 2 ) a (R) 3 ) b Y 1 c ...Formula 5

[0182] (In Equation 5, M) 1 R represents a metallic atom belonging to the group consisting of Groups 12, 13, and 14 of the periodic table. 2 and R 3 Y is a hydrocarbon group with 2 or more carbon atoms and less than 20 carbon atoms. 1 Hydroxyl group, silyl group, allyl group, amino group, amide group, -N=CR 4 ,R 5 -SR 6 (Here, R) 4 R 5 and R 6 This indicates a hydrocarbon group with 1 or more but less than 20 carbon atoms. When c is 2, Y... 1 (These can be different from each other) any of the β-keto acid residues, where α, β, a, b, and c are real numbers satisfying the following relationships: 0 ≤ α, 0 < β, 0 ≤ a, 0 ≤ b, 0 < a + b, 0 ≤ c / (α + β) ≤ 2, nα + 2β = a + b + c (where n represents M) 1 (valence).

[0183] 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, based on the molar ratio of magnesium atoms contained in (C-4) to titanium atoms contained in (C-5).

[0184] There are no particular limitations on the reaction temperature of (C-4) and (C-5), which is above -80°C and below 150°C, preferably above -40°C and below 100°C, and more preferably in the range of above -40°C and below 10°C.

[0185] There are no particular limitations on the concentration when using (C-4), but based on the number of titanium atoms contained in (C-4), it is preferably 0.1 mol / L or more and 2 mol / L or less, more preferably 0.5 mol / L or more and 1.5 mol / L or less. It should be noted that an inert hydrocarbon solvent is preferably used in the dilution of (C-4).

[0186] The order in which (C-4) and (C-5) are added to (C-3) is not particularly limited; it can be done by adding (C-5) after (C-4), adding (C-4) after (C-5), or adding (C-4) and (C-5) simultaneously. From the viewpoint of reducing entanglement, it is preferable to add (C-4) and (C-5) simultaneously after (C-3) has been pre-introduced into the reactor, allowing them to react at the same time. A mixture of dialkyl magnesium and triethylaluminum is preferred as (C-4). As for the mixing ratio of (C-4), in terms of the molar ratio relative to aluminum, (Mg / Al) is preferably 1 or more and 100 or less, more preferably 4 or more and 10 or less. By mixing organoaluminum, the dispersibility of organomagnesium is improved.

[0187] The reason given for controlling the molecular mobility index by simultaneously adding (C-4) and (C-5) is that the precipitation of particulate catalysts does not occur on the support surface, but rather in an inert hydrocarbon solvent. Each particulate catalyst is independently loaded on the support surface, thus suppressing the aggregation of active sites.

[0188] Furthermore, it is believed that by using dialkyl magnesium as (C-4), the reaction becomes more vigorous, further forming a particulate catalyst. The method of simultaneously adding (C-4) and (C-5) is preferred. The reaction temperature of (C-4) and (C-5) is preferably above -40°C and below 10°C. If within the above temperature range, even in a vigorous reaction, byproducts can be suppressed, maintaining the uniformity of particulate catalyst formation.

[0189] 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 resulting catalyst is used in the form of a slurry solution using an inert hydrocarbon solvent.

[0190] Next, (C-5) will be described. In this embodiment, (C-5) is a titanium compound represented by Formula 6 above.

[0191] (C-5): Ti(OR) 7 ) d X 1 （4-d） ...Formula 6

[0192] (In Equation 6, d is a real number greater than 0 and less than 4, R) 7 For hydrocarbon groups with 1 or more carbon atoms and less than 20, X 1 (These are halogen atoms.)

[0193] In Equation 6, as R 7The hydrocarbon group represented is not particularly limited, but examples include: aliphatic hydrocarbon groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, 2-ethylhexyl, heptyl, octyl, decyl, and aryl; alicyclic hydrocarbon groups such as cyclohexyl, 2-methylcyclohexyl, and cyclopentyl; and aromatic hydrocarbon groups such as phenyl and naphthyl. Aliphatic hydrocarbon groups are preferred. As a component of X... 1 The halogen atom represented is not particularly limited, but examples include chlorine, bromine, and iodine. Chlorine is preferred. One of the above-mentioned (C-5) halogen atoms may be used alone, or two or more may be used in combination.

[0194] There are no particular restrictions on the amount of titanium compound (C-5) used. From the viewpoint of increasing the distance between active sites, the molar ratio of titanium to magnesium atoms contained in the support (C-3) (Ti / Mg) is preferably 1 / 4 or less, more preferably 1 / 8 or less, more preferably 1 / 16 or less, and even more preferably 1 / 32 or less. When the molar ratio of titanium to magnesium atoms contained in the support (Ti / Mg) is below the upper limit, the density of active sites on the catalyst surface can be reduced, the number of active sites with aggregated structures can be reduced, and entanglement in the early stage of polymerization can be reduced, which is therefore preferred. On the other hand, a molar ratio of titanium to magnesium atoms contained in the support (Ti / Mg) of 1 / 64 or more is preferred in terms of catalyst activity.

[0195] There are no particular limitations on the reaction temperature of (C-5), but it is preferably above -80°C and below 150°C, more preferably above -40°C and below 100°C, and even more preferably in the range of above -20°C and below 60°C.

[0196] In this embodiment, there are no particular limitations on the method of loading (C-5) onto (C-3). Methods such as reacting (C-5) in excess of (C-3), loading (C-5) effectively by using a third component, and preferably loading (C-5) by reacting (C-5) with an organomagnesium compound (C-4) can be used.

[0197] [Surface treatment of solid catalysts]

[0198] As another example of the Ziegler-Natta catalyst used in this embodiment, the following olefin polymerization catalyst is also preferred, which comprises a solid catalyst [C] and an organometallic compound component [B], and the solid catalyst [C] is manufactured by treating the surface of the solid catalyst by reacting it with an organoaluminum compound (C-6) soluble in an inert hydrocarbon solvent as represented by Formula 7 (hereinafter also referred to as "surface treatment").

[0199] (C-6): AlR 12 jZ 1 （3-j） ...Formula 7

[0200] (In Equation 7, R) 12 Z is a hydrocarbon group with 1 or more carbon atoms and less than 20 carbon atoms. 1 (This refers to a group consisting of hydrogen atoms, halogen atoms, alkoxy groups, allyloxy groups, and silyloxy groups, where j is a number between 2 and 3.)

[0201] In equation 7 above, R 12 The hydrocarbon group representing 1 or more but less than 20 carbon atoms is not particularly limited. Specifically, it includes aliphatic hydrocarbons, aromatic hydrocarbons, and alicyclic hydrocarbons, such as trialkylaluminum compounds like trimethylaluminum, triethylaluminum, tripropylaluminum, tributylaluminum, tri(2-methylpropyl)aluminum (or triisobutylaluminum), tripentylaluminum, tri(3-methylbutyl)aluminum, trihexylaluminum, trioctylaluminum, and tridecylaluminum; aluminum halide compounds like diethylaluminum chloride, ethyl aluminum dichloride, bis(2-methylpropyl)aluminum chloride, ethyl sesquichloride, and diethylaluminum bromide; alkoxyaluminum compounds like ethoxydiethylaluminum and butoxybis(2-methylpropyl)aluminum; siloxyaluminum compounds like dimethylhydrosiloxydimethylaluminum, ethylmethylhydrosiloxydiethylaluminum, and ethyl dimethylsiloxydiethylaluminum; and mixtures thereof. Among these, trialkylaluminum compounds, diethylaluminum chloride, ethyl aluminum dichloride, and ethyl sesquichloride are particularly preferred.

[0202] The amount of (C-6) used is preferably 0.1 or more and 10 or less, more preferably 0.5 or more and 5 or less, based on the molar ratio of aluminum atoms contained in (C-6) to titanium atoms contained in the solid catalyst [C].

[0203] There are no particular limitations on the reaction temperature of (C-6) with the solid catalyst [C], which is above -80°C and below 150°C, preferably above -40°C and below 100°C, and more preferably in the range of above 0°C and below 60°C.

[0204] There are no particular limitations on the concentration when using (C-6), but based on the number of aluminum atoms contained in (C-6), it is preferably 0.1 mol / L or more and 2 mol / L or less, more preferably 0.5 mol / L or more and 1.5 mol / L or less. It should be noted that an inert hydrocarbon solvent is preferably used in the dilution of (C-6).

[0205] There are no particular restrictions on the method of adding (C-6) to the solid catalyst [C]. From an operational point of view, it is preferable to add (C-6) after the solid catalyst [C] has been pre-added to the reactor.

[0206] By treating the solid catalyst [C] with organoaluminum compounds, it can react with titanium compounds supported on the catalyst surface, thereby acting as a reduction reaction that changes the valence and freeing up excess titanium compounds.

[0207] From the perspective of controlling entanglement, it is possible to reduce the density of active sites on the catalyst surface and increase the distance between active sites. Therefore, it is preferable to use organoaluminum compounds (C-6) to treat the surface.

[0208] In this embodiment, the cleaning (decanting) after catalyst synthesis is preferably performed at least four times. By performing decanting at least four times, the amount of unreacted raw materials decreases, which tends to reduce scaling during polymerization.

[0209] [Cocatalyst]

[0210] Next, the organometallic compound component [B] used in this embodiment will be described. The solid catalyst [A] or solid catalyst [C] used in this embodiment, when combined with the organometallic compound component [B], becomes a highly active polymerization catalyst. The organometallic compound component [B] is sometimes also referred to as a "co-catalyst". As the organometallic compound component [B], it is preferably a compound containing a metal belonging to the group consisting of Groups 1, 2, 12 and 13 of the periodic table, and organoaluminum compounds and / or organomagnesium compounds are particularly preferred.

[0211] As organoaluminum compounds, compounds represented by the following formula 7 are preferred, either alone or in combination.

[0212] AlR 12 j Z 1 （3-j） ...Formula 7

[0213] (In Equation 7, R) 12 Z is a hydrocarbon group with 1 or more carbon atoms and less than 20 carbon atoms. 1 (This refers to a group consisting of hydrogen atoms, halogen atoms, alkoxy groups, allyloxy groups, and silyloxy groups, where j is a number between 2 and 3.)

[0214] In equation 7 above, R 12 There are no particular restrictions on the hydrocarbon group representing 1 or more but less than 20 carbon atoms. Specifically, it includes aliphatic hydrocarbons, aromatic hydrocarbons, and alicyclic hydrocarbons, with trialkylaluminum compounds being particularly preferred.

[0215] As organomagnesia compounds, organomagnesia compounds that are soluble in inert hydrocarbon solvents and represented by Formula 3 above are preferred.

[0216] (M) 2 ) γ (Mg)δ (R) 8 ) e (R) 9 ) f (OR) 10 ) g ...Equation 3

[0217] (In Equation 3, M) 2 R represents a metallic atom belonging to the group consisting of Groups 12, 13, and 14 of the periodic table. 8 R 9 and R 10 Each of these is a hydrocarbon group with 2 or more carbon atoms and less than 20 carbon atoms. 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 (where k represents M). 2 (The valence of the compound.)

[0218] This organomagnesium compound is represented as an organomagnesium complex soluble in inert hydrocarbon solvents, encompassing dialkylmagnesium compounds and their complexes with other metal compounds. Regarding γ, δ, e, f, g, M... 2 R 8 R 9 OR 10 As mentioned above, the organomagnesium compound preferably has higher solubility in inert hydrocarbon solvents, therefore δ / γ is preferably in the range of 0.5 or more and 10 or less. Furthermore, M is more preferably preferred. 2 It is a compound of aluminum.

[0219] From the viewpoint that the distance between the active sites participating in polymerization appears to widen, organoaluminum compounds represented by the following formula 8 are preferred as bulky organometallic compound components [B], either alone or in combination.

[0220] AlR 12 j R 13 k Z 1 （3-（j+k）） ...Formula 8

[0221] (In Equation 8, R) 12 R is a hydrocarbon group with 1 or more carbon atoms and less than 20 carbon atoms. 13 Z is a large hydrocarbon group. 1 Let j and k be real numbers that belong to the group consisting of hydrogen atoms, halogen atoms, alkoxy groups, allyloxy groups, and silyloxy groups, and let 0 < j, 0 < k, 0 < j + k ≤ 3.

[0222] In Equation 8 above, R13 The bulky hydrocarbon group represented is not particularly limited, but specifically includes 2,6-di-tert-butylphenoxy, 2,6-di-tert-butyl-4-methylphenoxy, 2,6-di-tert-butyl-4-ethylphenoxy, 2,4,6-tri-tert-butylphenoxy, 2,6-diisopropylphenoxy, 2,6-di-sec-butylphenoxy, 2,6-dicyclohexylphenoxy, and 2,6-diphenylphenoxy. Due to the steric hindrance of the bulky cocatalyst, the distance between the activated active sites increases. (2,6-di-tert-butyl-4-methylphenoxy)diethylaluminum is particularly preferred as a bulky cocatalyst.

[0223] Furthermore, it is preferable to mix butylated hydroxytoluene (BHT) dissolved in an inert hydrocarbon solvent with the organoaluminum compound of Formula 7 in a ratio of 0.9 to 1.9 based on the molar ratio of BHT to aluminum (BHT / Al).

[0224] It should be noted that there is no particular limitation on the combination ratio of solid catalyst [A] or solid catalyst [C] and organometallic compound component [B]. However, relative to 1g of solid catalyst [A] or solid catalyst [C], the organometallic compound component [B] is preferably 1 mmol or more and 3000 mmol or less.

[0225] There are no particular restrictions on the method of adding organometallic compound component [B] to the polymerization system under polymerization conditions. It can be added to the polymerization system separately from the catalyst component mentioned above, or it can be added to the polymerization system after reacting with the catalyst component mentioned above beforehand.

[0226] There are no particular limitations on the concentration of the organometallic compound component [B] in the polymerization system. From the viewpoint of completely capturing impurities and the amount of metal residue in the polymer, it is preferably 0.001 mmol / L or more and 10 mmol / L or less, more preferably 0.01 mmol / L or more and 5 mmol / L or less, and even more preferably 0.05 mmol / L or more and 2 mmol / L or less.

[0227] On the other hand, in order to obtain the ultra-high molecular weight polyethylene powder of this embodiment, it is preferable to have a structure in which the molecular chains can slide easily. For example, a method of polymerizing to obtain a straight-chain polymer without branches can be cited. Specifically, it is preferable to use a mixture of two or more organometallic compounds as components [B].

[0228] [Polymerization method for ultra-high molecular weight polyethylene powder]

[0229] Examples of polymerization methods for manufacturing the ultra-high molecular weight polyethylene powder of this embodiment include, but are not limited to, slurry polymerization, gas-phase polymerization, and solution polymerization. Among these, slurry polymerization, which can effectively remove the heat of polymerization, is preferred.

[0230] In slurry polymerization, inert hydrocarbon media can be used as the medium; alternatively, olefins themselves can also be used as the medium. Examples of such inert hydrocarbon media include: aliphatic hydrocarbons such as propane, butane, isobutane, pentane, isopentane, hexane, heptane, octane, decane, dodecane, and kerosene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane; aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as chloroethane, chlorobenzene, and dichloromethane; and mixtures thereof, but are not limited to these.

[0231] The polymerization reaction in the polyethylene powder manufacturing method of this embodiment can be carried out in any of the following methods: batch, semi-continuous, or continuous.

[0232] Alternatively, polymerization can be carried out in two or more stages with different reaction conditions.

[0233] The polymerization temperature range of the ethylene polymer in the polyethylene powder manufacturing method of this embodiment is preferably 30°C or higher and 100°C or lower, more preferably 35°C or higher and 95°C or lower, and even more preferably 40°C or higher and 90°C or lower.

[0234] By using a polymerization temperature above 30°C, it is possible to manufacture efficiently in industry. On the other hand, by using a polymerization temperature below 100°C, it is possible to suppress the formation of blocky scale caused by partial melting of the polymer, enabling continuous and stable manufacturing without clogging pipes.

[0235] The polymerization pressure range of the ethylene polymer in the polyethylene powder manufacturing method of this embodiment is preferably above atmospheric pressure and below 2 MPaG, more preferably above 0.2 MPaG and below 1.5 MPaG, and even more preferably above 0.3 MPaG and below 0.9 MPaG.

[0236] By using polymerization pressures above atmospheric pressure, it is possible to manufacture efficiently in industry. On the other hand, by using polymerization pressures below 2 MPaG, there is a tendency to manufacture stably without producing lumpy scale caused by rapid polymerization in the polymerization reactor.

[0237] The molecular weight of ethylene polymers can be adjusted, as described in German Patent Application Publication No. 3127133, by introducing hydrogen into the polymerization system or by changing the polymerization temperature.

[0238] By adding hydrogen as a chain transfer agent to the polymerization system, the molecular weight can be controlled within an appropriate range. When adding hydrogen to the polymerization system, the range of 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.

[0239] Alternatively, hydrogen can be added to the polymerization system through the catalyst inlet line after being pre-contaminated with the catalyst. Immediately after the catalyst is introduced into the polymerization system, the catalyst concentration near the inlet line outlet becomes high, thus increasing the likelihood of rapid polymerization and the generation of localized high-temperature conditions. On the other hand, by contacting the hydrogen and catalyst before introducing them into the polymerization system, the initial activity of the catalyst can be suppressed, preventing the formation of lumpy scale caused by rapid polymerization and catalyst deactivation at high temperatures.

[0240] Typically, when polymerizing ethylene-based polymers, antistatic agents such as Stadis and STATSAFE, manufactured by Innospec (distributed by Maruwa & Co.), can be used to suppress electrostatic adhesion of the polymer to the polymerization reactor.

[0241] For antistatic agents such as Stadis and STATSAFE, the antistatic agent diluted in an inert hydrocarbon medium can also be added to the polymerization reactor via a pump or the like. In methods such as pre-adding to a solid catalyst or adding to the polymerization reactor, the amount added is preferably 1 ppm or more and 500 ppm or less relative to the production rate of ethylene polymers per unit time, more preferably 10 ppm or more and 100 ppm or less.

[0242] It should be noted that, in this embodiment, in addition to the components mentioned above, other components (additives, etc.) that are useful for the manufacture (polymerization) of polyethylene may also be used.

[0243] The solvent separation method in the polymerization process of polyethylene powder in this embodiment can be any of the following: decantation, centrifugation, or filter filtration. Filter filtration, which is simple to separate ethylene polymers from solvents, is preferred.

[0244] There are no particular limitations on the method of deactivating the catalyst used in the polymerization process of the ethylene polymer that constitutes the polyethylene powder of this embodiment. It is preferable to deactivate the catalyst after separating the ethylene polymer from the solvent.

[0245] By introducing polyethylene powder into a reagent used to deactivate the catalyst after separating the polyethylene powder from the solvent, it is possible to suppress the precipitation of low molecular weight components and catalyst components contained in the solvent into ethylene polymers.

[0246] There are no particular limitations on the reagents that can deactivate catalysts. Examples include: oxygen, water, alcohols, glycols, phenols, carbon monoxide, carbon dioxide, ethers, carbonyl compounds, alkynes, etc.

[0247] In the method for manufacturing polyethylene powder according to this embodiment, it is preferable to perform a drying step after separating the ethylene polymer from the solvent. In the drying step, a rotary kiln, a paddle dryer, or a flow dryer is preferred. Furthermore, the drying temperature is preferably 30°C or higher and 150°C or lower.

[0248] In addition, introducing inactive gases such as nitrogen into the dryer to promote drying is also effective. At this point, methods such as entraining steam as a catalyst deactivator are even more effective.

[0249] After the ethylene polymer constituting the polyethylene powder of this embodiment is dried, it can be sieved to remove coarse powder.

[0250] The polyethylene powder in this embodiment can be a mixture of various polyethylene powders containing ethylene polymers obtained by the above manufacturing method.

[0251] In addition, it can be used in combination with known additives such as slip agents, neutralizers, antioxidants, light stabilizers, antistatic agents, and pigments, as needed.

[0252] There are no particular limitations on the types of substances that can be used as lubricants or neutralizers. Examples include: aliphatic hydrocarbons, higher fatty acids, metal salts of higher fatty acids, fatty acid esters of alcohols, waxes, higher fatty acid amides, silicone oils, rosin, etc. Specifically, stearates such as calcium stearate, magnesium stearate, and zinc stearate are preferred additives. There are no particular limitations on the content of lubricants or neutralizers, but they should be below 5000 ppm, below 4000 ppm, or below 3000 ppm.

[0253] There are no particular limitations on antioxidants; for example, phenolic compounds or phenolic phosphoric acid compounds are preferred. Specifically, examples include: phenolic antioxidants such as 2,6-di-tert-butyl-4-methylphenol (dibutylhydroxytoluene), octadecyl 3-(4-hydroxy-3,5-di-tert-butylphenyl)propionate, and tetra(methylene(3,5-di-tert-butyl-4-hydroxyhydrogenated cinnamate))methane; phosphorus-containing phenolic antioxidants such as 6-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosphazene; and phosphorus-containing antioxidants such as tetra(2,4-di-tert-butylphenyl) 4,4'-biphenylene diphosphonate, tris(2,4-di-tert-butylphenyl) phosphite, and cyclic neopentanetetramethylbis(2,4-tert-butylphenyl phosphite). There is no particular limitation on the content of antioxidants, but it is 5% or less, preferably 3% or less, and more preferably 1% or less. By using antioxidants of 5% or less, the deterioration of polyethylene can be inhibited, thus making it less prone to embrittlement, discoloration, and reduction in mechanical properties, resulting in better long-term stability.

[0254] There are no particular limitations on the light stabilizer used. Examples include benzotriazole light stabilizers such as 2-(5-methyl-2-hydroxyphenyl)benzotriazole and 2-(3-tert-butyl-5-methyl-2-hydroxyphenyl)-5-chlorobenzotriazole; hindered amine light stabilizers such as bis(2,2,6,6-tetramethyl-4-piperidinium) sebacic acid and poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidinyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidinyl)imino}]. The content of the light stabilizer is not particularly limited, but is preferably 5000 ppm or less, more preferably 3000 ppm or less, and more preferably 2000 ppm or less.

[0255] As an antistatic agent, there are no particular restrictions. Examples include: aluminosilicates, kaolin, clay, natural silica, synthetic silica, silicates, talc, diatomaceous earth, glycerol fatty acid esters, etc.

[0256] [use]

[0257] The ultra-high molecular weight polyethylene powder of this embodiment can be used as a raw material for various molded bodies such as microporous membranes, fibers, especially high-strength fibers, sintered bodies, compression molded bodies, and plunger extrusion molded bodies.

[0258] In particular, the polyethylene powder of this embodiment is suitable as a raw material for high-strength fibers.

[0259] [Molded body]

[0260] The molded body in this embodiment is the molded body of the ultra-high molecular weight polyethylene powder described in this embodiment above.

[0261] There are no particular limitations on the manufacturing method of the molded body. For example, a molding method can be listed as a process of extruding, stretching, extracting and drying resin using wet extrusion.

[0262] There are no particular limitations on the manufacturing method of fibers (e.g., high-strength fibers). For example, a method can be listed as obtaining fibers by mixing liquid paraffin with the above-mentioned ultra-high molecular weight polyethylene powder, spinning it, and then heating and stretching it. Specifically, there are no particular limitations, and for example, the following manufacturing method under general swelling conditions can be listed.

[0263] Ultra-high molecular weight polyethylene (UHMWPE) powder, liquid paraffin, and additives such as antioxidants (if desired) are combined and stirred at a temperature at least 30°C lower than the melting point (Tm2) of the UHMWPE powder to prepare a slurry-like liquid. The slurry-like liquid is then fed into a mixer and mixed at a specific temperature. Next, it is spun through a spinneret mounted at the front of an extruder. The filament containing liquid paraffin is then wound away from the spinneret. To remove the liquid paraffin from the wound filament, it is extracted by immersing it in hexane and then dried.

[0264] The obtained filament is stretched once in a constant temperature bath, and then stretched a second time in the constant temperature bath until the filament is about to break, thereby obtaining high-strength fiber (drawn filament).

[0265] [High-strength fiber]

[0266] Specific manufacturing methods for high-strength fibers include, for example, a manufacturing method that includes a sizing process, a gelation process, an optional compounding process, an optional extrusion preparation process, an extrusion process, an optional quenching process, an extraction process, and a raw yarn stretching process.

[0267] (Pulping process)

[0268] The slurry process involves mixing the aforementioned ultra-high molecular weight polyethylene powder and the first liquid paraffin, and stirring the mixture at a temperature below the melting point of the ultra-high molecular weight polyethylene powder to obtain the slurry.

[0269] The stirring temperature is preferably 25°C or higher and 120°C or lower, more preferably 50°C or higher and 115°C or lower, even more preferably 80°C or higher and 110°C or lower, and particularly preferably 90°C or higher and 105°C or lower.

[0270] By setting the stirring temperature to above 25°C, liquid paraffin can be efficiently penetrated into the pores of ultra-high molecular weight polyethylene powder. Furthermore, by setting the stirring temperature to below 120°C, melting of the surface of the ultra-high molecular weight polyethylene powder can be suppressed, preventing the powder particles from fusing together, thereby obtaining a uniform gel with untangled molecular chains.

[0271] (Gelification process)

[0272] The gelation process involves mixing the above-mentioned slurry with a second liquid paraffin at a temperature of 150°C or higher and 300°C or lower to obtain a gel for raw silk at a temperature of 140°C or higher and 200°C or lower.

[0273] By adjusting the temperature of the gel used for the precursor fibers to above 140°C, a uniform gel with untangled molecular chains can be obtained in a short time. Furthermore, by adjusting the temperature of the gel used for the precursor fibers to below 200°C, the significant decrease in molecular weight caused by thermal decomposition can be suppressed.

[0274] The temperature of the second liquid paraffin is preferably 150°C or higher and 250°C or lower, more preferably 150°C or higher and 200°C or lower, and even more preferably 150°C or higher and 180°C or lower.

[0275] The temperature of the gel used for the precursor fiber is preferably 140°C or higher and 190°C or lower, more preferably 140°C or higher and 180°C or lower, and even more preferably 140°C or higher and 170°C or lower.

[0276] The polyethylene concentration of the gel used for the precursor fiber is preferably 3% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 15% by mass or less, even more preferably 3% by mass or more and 10% by mass or less, and particularly preferably 3% by mass or more and 8% by mass or less.

[0277] By adjusting the polyethylene concentration of the gel used for spinning the precursor yarn to 3% by mass or more, precursor yarns with small diameter inconsistencies can be stably spun. Furthermore, by adjusting the polyethylene concentration of the gel used for spinning the precursor yarn to 20% by mass or less, precursor yarns with untangled molecular chains can be obtained.

[0278] (Mixing process)

[0279] The mixing process is the process of mixing the raw yarn with gel.

[0280] The mixing temperature is preferably above 140°C and below 200°C, more preferably above 140°C and below 180°C, even more preferably above 140°C and below 170°C, and particularly preferably above 150°C and below 160°C.

[0281] By setting the mixing temperature to above 140°C, a uniform gel with untangled molecular chains can be obtained. Furthermore, by setting the mixing temperature to below 200°C, the significant decrease in molecular weight caused by thermal decomposition can be suppressed.

[0282] The mixing time is preferably 5 minutes or more and 180 minutes or less, more preferably 10 minutes or more and 150 minutes or less, even more preferably 15 minutes or more and 90 minutes or less, and particularly preferably 30 minutes or more and 60 minutes or less.

[0283] By setting the mixing time to 5 minutes or more, a uniform gel with untangled molecular chains can be obtained. Furthermore, by setting the mixing time to 180 minutes or less, the significant decrease in molecular weight caused by thermal decomposition can be suppressed.

[0284] The mixing speed is preferably 3 rpm or more and 50 rpm or less, more preferably 3 rpm or more and 30 rpm or less, even more preferably 3 rpm or more and 20 rpm or less, and particularly preferably 3 rpm or more and 10 rpm or less.

[0285] By setting the mixing speed to 3 rpm or higher, a uniform gel with untangled molecular chains can be obtained. Furthermore, by setting the mixing speed to 50 rpm or lower, significant molecular weight reduction due to thermal decomposition can be suppressed.

[0286] (Extrusion preparation process)

[0287] The extrusion preparation process is the process of preparing the precursor fibers for extrusion using gel. Specific examples of extrusion preparation include temperature control and degassing of the precursor fiber gel.

[0288] The temperature of the extrusion preparation process is preferably above 140°C and below 200°C, more preferably above 140°C and below 190°C, even more preferably above 140°C and below 180°C, and particularly preferably above 150°C and below 180°C.

[0289] By setting the temperature of the extrusion preparation process to 140°C or higher, liquid paraffin can be prevented from flowing out of the gel used for precursor fibers, and fluctuations in gel concentration can be suppressed, thereby ensuring a stable supply of precursor fibers. Furthermore, by setting the temperature of the extrusion preparation process to 200°C or lower, significant molecular weight reduction caused by thermal decomposition can be suppressed.

[0290] The time for the extrusion preparation process (e.g., the degassing time) is preferably 5 minutes or more and 90 minutes or less, more preferably 5 minutes or more and 60 minutes or less, even more preferably 15 minutes or more and 60 minutes or less, and particularly preferably 30 minutes or more and 60 minutes or less.

[0291] By setting the extrusion preparation time to 5 minutes or more, the gel for the precursor fiber can be sufficiently degassed, resulting in a stable precursor fiber. Furthermore, by setting the extrusion preparation time to 90 minutes or less, significant molecular weight reduction due to thermal decomposition can be suppressed.

[0292] (Extrusion process)

[0293] The extrusion process is the process of extruding the above-mentioned precursor fibers with gel to obtain precursor fibers.

[0294] The extrusion speed is preferably 5 mm / min or more and 20 mm / min or less, more preferably 5 mm / min or more and 15 mm / min or less, even more preferably 7.5 mm / min or more and 12 mm / min or less, and particularly preferably 7.5 mm / min or more and 10 mm / min or less.

[0295] By setting the extrusion speed to 5 mm / min or higher, it is possible to recycle the filament without applying tension. In the filament stretching process, it is possible to stretch to a high ratio, resulting in highly oriented (high-strength) filaments. Furthermore, by setting the extrusion speed to 20 mm / min or lower, the ejection rate can be stabilized, and filaments with small diameter variations can be consistently obtained.

[0296] The winding speed is preferably 200 mm / min or more and 1600 mm / min or less, more preferably 200 mm / min or more and 1400 mm / min or less, even more preferably 250 mm / min or more and 1000 mm / min or less, and particularly preferably 500 mm / min or more and 800 mm / min or less.

[0297] By setting the winding speed to 200 mm / min or higher, it is possible to retract the yarn without applying tension. During the yarn stretching process, it is possible to stretch the yarn to a high ratio, resulting in highly oriented (high-strength) yarn. Furthermore, by setting the winding speed to 1600 mm / min or lower, the output can be stabilized, and yarns with small diameter variations can be consistently obtained.

[0298] The spray volume is preferably 0.2 g / min or more and 1.5 g / min or less, more preferably 0.2 g / min or more and 1.2 g / min or less, even more preferably 0.2 g / min or more and 1.0 g / min or less, and particularly preferably 0.3 g / min or more and 0.8 g / min or less.

[0299] By setting the ejection rate to 0.2 g / min or more, it is possible to recover the filament without applying tension, and in the filament stretching process, it is possible to stretch to a high ratio, resulting in highly oriented (high-strength) filaments. Furthermore, by setting the ejection rate to 1.5 g / min or less, melt fracture can be suppressed, and filaments with small diameter inconsistencies can be stably obtained.

[0300] The diameter of the spinneret is preferably 0.8 mm or more and 1.5 mm or less, more preferably 0.8 mm or more and 1.2 mm or less, even more preferably 0.8 mm or more and 1.0 mm or less, and particularly preferably 0.9 mm or more and 1.0 mm or less.

[0301] By setting the spinneret diameter to 0.8 mm or more, the diameter of the raw filament after liquid paraffin extraction can be adjusted to a certain degree, allowing for high stretching ratios during the raw filament stretching process, thereby obtaining highly oriented (high-strength) filaments. Furthermore, by setting the spinneret diameter to 1.5 mm or less, the time required to extract liquid paraffin from the raw filament can be shortened, enabling efficient extraction operations.

[0302] (Quick cooling process)

[0303] The rapid cooling process is the process of rapidly cooling the aforementioned raw yarn. There are no particular limitations on the method of rapid cooling; for example, passing the raw yarn through a water bath can be used.

[0304] The time from the extrusion process to the quenching process (e.g., the time until the extruded filament enters the water bath) is preferably 0 seconds or more and 10 seconds or less, more preferably 0 seconds or more and 5 seconds or less, and even more preferably 0 seconds or more and 2 seconds or less.

[0305] By setting the time from the extrusion process to the rapid cooling process to less than 10 seconds, the molten filament can be rapidly cooled and solidified, minimizing the unevenness of the filament diameter.

[0306] In the rapid cooling process, when the raw yarn passes through a water bath, the distance from the spinneret to the water surface of the water bath is preferably 0 cm or more and 10 cm or less, more preferably 1 cm or more and 8 cm or less, even more preferably 1 cm or more and 5 cm or less, and particularly preferably 1 cm or more and 3 cm or less.

[0307] By setting the distance from the spinneret to the water surface of the water bath to less than 10cm, the molten filament can be rapidly cooled and solidified, minimizing the unevenness of the filament diameter.

[0308] The temperature of the quenching process is preferably above 5°C and below 30°C, more preferably above 5°C and below 25°C, even more preferably above 5°C and below 20°C, and particularly preferably above 5°C and below 15°C.

[0309] By setting the temperature of the quenching process to above 5°C, cooling costs can be suppressed and production can be carried out efficiently. In addition, by setting the temperature of the quenching process to below 30°C, the molten precursor fibers can be rapidly cooled and solidified, minimizing the unevenness of the precursor fiber diameter.

[0310] (Extraction process)

[0311] The extraction process is a process of extracting the first liquid paraffin and the second liquid paraffin from the above-mentioned raw silk to obtain the raw silk for drawing.

[0312] To extract liquid paraffin, an extraction solvent is preferred. There are no particular limitations on the extraction solvent; examples include hexane and dichloromethane.

[0313] There are no particular limitations on the extraction method; for example, the method of immersing the raw silk in an extraction solvent can be listed.

[0314] The extraction time is preferably 3 hours or more and 24 hours or less, more preferably 3 hours or more and 20 hours or less, even more preferably 5 hours or more and 20 hours or less, and particularly preferably 10 hours or more and 20 hours or less.

[0315] By setting the extraction time to 3 hours or more, liquid paraffin can be extracted to a level suitable for use as a starting material for drawing. When a large amount of liquid paraffin remains in the starting material for drawing, the molecular chains become highly mobile and prone to high orientation when heat is applied during the drawing process, but this state is difficult to maintain (it easily reverts to the state before high orientation). Therefore, it is difficult to obtain high-strength yarn. On the other hand, by setting the extraction time to 24 hours or less, starting material for drawing can be obtained efficiently without reducing productivity.

[0316] (Pre-filament stretching process)

[0317] The raw yarn stretching process is a process of heating and stretching the raw yarn used for stretching as described above.

[0318] The stretching process is preferably multi-stage stretching, and more preferably two-stage stretching. Two-stage stretching preferably includes a primary stretching step and a secondary stretching step.

[0319] (One stretching process)

[0320] The delivery speed is preferably 50 mm / min or more and 200 mm / min or less, more preferably 50 mm / min or more and 150 mm / min or less, even more preferably 50 mm / min or more and 120 mm / min or less, and particularly preferably 50 mm / min or more and 100 mm / min or less.

[0321] The winding speed is preferably 1000 mm / min or more and 4000 mm / min or less, more preferably 1000 mm / min or more and 3500 mm / min or less, even more preferably 1500 mm / min or more and 3500 mm / min or less, and particularly preferably 2000 mm / min or more and 3000 mm / min or less.

[0322] It should be noted that the stretch ratio is controlled by adjusting the feed speed and winding speed, and the setting is also based on productivity considerations.

[0323] The stretching temperature is preferably above 110°C and below 155°C, more preferably above 110°C and below 150°C, even more preferably above 115°C and below 145°C, and particularly preferably above 120°C and below 140°C.

[0324] By setting the stretching temperature to 110°C or higher, stretching can be performed under conditions of high molecular chain mobility, achieving high orientation. Furthermore, by setting the stretching temperature to 155°C or lower, stretching can be performed without melting the precursor fiber.

[0325] (Secondary stretching process)

[0326] The delivery speed is preferably 50 mm / min or more and 200 mm / min or less, more preferably 50 mm / min or more and 150 mm / min or less, even more preferably 50 mm / min or more and 120 mm / min or less, and particularly preferably 50 mm / min or more and 100 mm / min or less.

[0327] The winding speed is preferably 100 mm / min or more and 500 mm / min or less, more preferably 100 mm / min or more and 450 mm / min or less, even more preferably 150 mm / min or more and 400 mm / min or less, and particularly preferably 200 mm / min or more and 300 mm / min or less.

[0328] It should be noted that the stretch ratio is controlled by adjusting the feed speed and winding speed, and the setting is also based on productivity considerations.

[0329] The stretching temperature is preferably 130°C or higher and 155°C or lower, more preferably 130°C or higher and 150°C or lower, even more preferably 135°C or higher and 150°C or lower, and particularly preferably 140°C or higher and 150°C or lower.

[0330] By setting the stretching temperature above 130°C, stretching can be performed under conditions of high molecular chain mobility, enabling high orientation. Furthermore, by setting the stretching temperature below 155°C, stretching can be performed without melting the primary stretching filament.

[0331] Example

[0332] The present invention will now be described in more detail using examples and comparative examples, but the invention is not limited to the following examples. Unless otherwise specified, all operations are performed at room temperature.

[0333] In this application, the ethylene and hexane used in the examples and comparative examples were dehydrated using MS-3A (manufactured by Showa Union), and the hexane was deoxygenated by further depressurization using a vacuum pump before use.

[0334] The physical properties of the ultra-high molecular weight polyethylene powders of the examples and comparative examples were determined using the following methods.

[0335] (1) Intrinsic viscosity IV

[0336] The intrinsic viscosity IV of the polyethylene powders obtained in the examples and comparative examples was determined in accordance with ISO 1628-3 (2010).

[0337] As a solvent, 20 mL of decahydronaphthalene (containing 1 g / L of 2,6-di-tert-butyl-4-methylphenol) was used after being degassed by a vacuum pump and purged with nitrogen.

[0338] As a viscosity tube, a Canon-Fensk viscometer (manufactured by Shibata Scientific Instruments Co., Ltd.: product number-100) was used. Measurements were repeated three times, and the average of the three results was used.

[0339] (2) The kinematic index and entanglement degree of slurry containing ultra-high molecular weight polyethylene powder

[0340] The kinematic index and entanglement degree of the ultra-high molecular weight polyethylene powder obtained in the examples and comparative examples were determined using pulsed NMR. A slurry was prepared by filling a sample tube with 0.12 g of polyethylene powder, 0.28 g of liquid paraffin (MORESCO liquid paraffin, product name: SMOIL P-350P) and 0.004 g of antioxidant (ADK STAB AO-60G antioxidant, ADEKA) with a diameter of 7 mm and a height of 45 mm. The sample tube containing the slurry was placed in a 9 mm diameter, 180 mm high measurement sample tube and left to stand for 20 hours in a constant temperature chamber controlled at 22°C and 60% humidity, allowing sufficient immersion time, thus preparing a sample. The measurement sample tube was then placed in a Bruker TD-NMR apparatus (model: minispec mq20) with an internal temperature set to 30°C, and the sample was heated according to the <Heating Conditions> described below.

[0341] The liquid paraffin used in the slurry kinematics test was SMOIL P-350P manufactured by MORESCO Co., Ltd., with the following representative properties: density at 15°C: 0.866 g / cm³. 3 Pour point: -10℃; Kinematic viscosity at 40℃: 68.00 mm 2 / s (cSt), kinematic viscosity at 100℃: 9.188 mm 2 / s (cSt), cycloalkanes analysis: Cn: 30%, Cp: 70%, average molecular weight: 489 g / mol.

[0342] The temperatures shown in the following <Heating Conditions> section are values ​​obtained by measuring the internal temperature of the sample using a thermocouple.

[0343] <Heating conditions>

[0344] Increase the temperature by 10°C / minute and maintain it at 60°C for 23 minutes.

[0345] Increase the temperature by 10°C / minute and maintain it at 90°C for 23 minutes.

[0346] Increase the temperature by 10°C / minute and maintain it at 105°C for 23 minutes.

[0347] Increase the temperature by 10°C / minute and maintain it at 120°C for 23 minutes.

[0348] Increase the temperature by 5°C / minute and maintain it at 130°C for 26 minutes.

[0349] Increase the temperature by 5°C / minute and maintain it at 140°C for 26 minutes.

[0350] Increase the temperature by 5°C / minute and maintain it at 150°C for 10 minutes.

[0351] It should be noted that, considering the deviation from the target temperature (actual temperature) of the sample, the set temperature of the device was corrected using calibration straight lines (Equation A) and (Equation B). The decimal places were rounded to the nearest whole number.

[0352] (In the case of temperatures above 0℃ and below 100℃) y = 1.0984x + 260.88 (Equation A)

[0353] (When the temperature is greater than 100℃ and less than or equal to 200℃) y = 1.1729x + 252.21 (Equation B)

[0354] x = target temperature (°C), y = set temperature (K)

[0355] After the above-described heating process was completed, the spin-spin relaxation time (T2, sometimes referred to as "relaxation time" in this specification) of the sample at 150°C was measured under the following <Measurement Conditions>.

[0356] <Measurement Conditions>

[0357] Magnetic field strength: 0.47T

[0358] Nuclear type determined: 1H (20MHz)

[0359] Determination method: Carr Purcell Meiboom Gill method

[0360] Total number of times: 256

[0361] Repeat time: 3 seconds

[0362] The interval (τ) between the initial 90° pulse and the 180° pulse: 0.04 milliseconds

[0363] Total echo signal count: 6400

[0364] Heater power: 5%

[0365] The free induction decay (FID) obtained by measurement was curve-fitted using the TD-NMR-A analysis program manufactured by Bruker (fitting range: the entire range, i.e., t = 0.10032 to 567.8196). The function shown in Equation 1 below was used in the fitting.

[0366] <Formula 1>

[0367] f(t)=Rαexp(-t / Tα)+Rβexp(-t / Tβ)+Rγexp(-t / Tγ)

[0368] (Where, Rα+Rβ+Rγ=100)

[0369] t: variable (time)

[0370] Tα: Relaxation time (milliseconds) of the low-momentum component α.

[0371] Rα: The proportion of the low-motor component α present.

[0372] Tβ: Relaxation time (milliseconds) of the motion-centered component β.

[0373] Rβ: The proportion of the motility-intermediate component β present.

[0374] Tγ: Relaxation time (milliseconds) of the highly mobile component γ.

[0375] Rγ: The proportion of highly mobile component γ present.

[0376] Finally, based on the relaxation times T and existence ratios R obtained by curve fitting through free induction decay, as shown in Equations (I) and (II) below, the kinematic index (milliseconds) and entanglement degree are calculated. This operation is repeated 5 times, and the average of the 3 points excluding the maximum and minimum values ​​is calculated to obtain the final kinematic index and entanglement degree.

[0377] (Motor performance index) = Tα×Rα / (Rα+Rβ) + Tβ×Rβ / (Rα+Rβ) (Equation I)

[0378] (Degree of entanglement) = Rβ / Rα (Equation II)

[0379] Temperature correction method

[0380] <Correction Method>

[0381] 1. The heater power of the device was set to 5%, and the calibration straight lines (Equation A) and (Equation B) were obtained by following the steps below. Polyethylene powder was filled into a 9 mm diameter, 180 mm high sample tube for measurement until it was 1 cm from the bottom, and a thermocouple was inserted.

[0382] 2. Place the sample tubes for measurement into a Bruker TD-NMR apparatus (model: minispec mq20) with the device temperature set to 0°C.

[0383] 3. After putting it into operation, record the thermocouple value after 5 minutes.

[0384] 4. After more than 10 minutes from the start of operation, set the temperature to 10℃ and start heating.

[0385] 5. Record the thermocouple value 5 minutes after the heating ends (device temperature = set temperature).

[0386] 6. After more than 10 minutes from the end of the heating process, set the temperature to 20℃ and start heating again.

[0387] 7. Then, repeat steps (5) and (6) at 10°C intervals until 200°C.

[0388] 8. Plot the recorded thermocouple temperature on the horizontal axis and the set temperature on the vertical axis, and approximate the result with a straight line.

[0389] (3) Through 13 Comonomer content determined by C-NMR

[0390] Through polyethylene powder 13 The determination of the comonomer (olefin capable of copolymerizing with ethylene) content by C-NMR was performed according to the method disclosed in GJ Ray et al., Macromolecules, 10, 773 (1977), using a method that... 13 The signal of methylene carbon observed by C-NMR spectrum is calculated from its area intensity.

[0391] Measurement device: ECS-500 manufactured by NEC Corporation

[0392] Observation nucleus: 13 C

[0393] Observation frequency: 100.53MHz

[0394] Pulse width: 45° (7.5 microseconds)

[0395] Pulse program: single pulse dec

[0396] PD: 5 seconds

[0397] Measurement temperature: 130℃

[0398] Cumulative count: 30,000 or more

[0399] Reference: PE (-eee-) signal, 29.9ppm

[0400] Solvent: o-dichlorobenzene-d4

[0401] Sample concentration: 5% to 10% by weight

[0402] Dissolution temperature: 130℃~140℃

[0403] (4) Ti content and Al content

[0404] The Ti and Al contents of the polyethylene powders obtained in the examples and comparative examples were evaluated by high-frequency inductively coupled plasma mass spectrometry (ICP-MS) according to JIS K 0133. Sample preparation was carried out using a microwave decomposition apparatus (model ETHOS TC, manufactured by Milestone General) and pressure decomposition with nitric acid. For the prepared samples, the elemental concentrations of titanium (Ti) and aluminum (Al) were determined using ICP-MS (inductively coupled plasma mass spectrometry apparatus, model X-series X7, manufactured by Thermo Fisher Scientific) via the internal standard method, and these were recorded as the Ti and Al contents, respectively.

[0405] (5) D 10 D 50 and D 90 Determination method

[0406] The particle size of the ultra-high molecular weight polyethylene powders obtained in the examples and comparative examples was measured using a laser diffraction particle size distribution measuring device (Mastersizer 3000 manufactured by Malvern Panalytical). Based on this measurement, a cumulative particle size distribution was prepared from the smallest particle size side, and the particle sizes at which the cumulative distribution reached 10%, 50%, and 90% were respectively taken as D. 10 D 50 and D90 Repeat the measurement three times and use the average of the three results.

[0407] Dispersion medium: soapy water (purified water containing 1% by weight of IGEPAL (registered trademark) CO-630)

[0408] <Manufacturing Method 1 for High-Strength Fibers>

[0409] [Swelling process]

[0410] High-strength fibers were manufactured using ultra-high molecular weight polyethylene (UHMWPE) powder as described below. When the total amount of UHMWPE powder and liquid paraffin was set at 100 parts by weight, 15 parts by weight of UHMWPE powder, 85 parts by weight of liquid paraffin (liquid paraffin manufactured by MORESCO Co., Ltd. (product name: SMOIL P-350P)), and 1 part by weight of antioxidant (antioxidant manufactured by ADEKA Co., Ltd. (ADK STAB AO-60G)) were combined at a point higher than the melting point (T) of the UHMWPE powder. m2 The liquid was prepared by stirring at a temperature of 35°C for 60 minutes.

[0411] [Mixing Process]

[0412] Next, the slurry-like liquid was added to liquid paraffin (liquid paraffin manufactured by MORESCO Co., Ltd. (product name: SMOIL P-350P)) at 160°C and stirred for 2 minutes to produce a gel with a polymer concentration of 5 parts by mass. The resulting gel was then added to a Labo Plastomill (main model: 4C150-01) manufactured by Toyo Seiki Co., Ltd., and kneaded at a constant temperature of 150°C for 180 minutes at a screw speed of 10 rpm to produce a compounded gel.

[0413] [Spinning process]

[0414] Next, spinning was performed using a Capillograph 1D (main model: PMD-C) manufactured by Toyo Seiki Co., Ltd. The compounded gel was fed into a furnace set to 180°C using an orifice with a diameter of 1.0 mm, a length of 66 mm, and an inflow angle of 90°, and then degassed for 60 minutes. The extrusion speed was then set to 7.5 mm / min to achieve an ejection rate of 0.35 g / min, and the yarn was wound back at a speed of 2.8 m / min through a water bath immediately below the orifice tip. It should be noted that the distance from the orifice tip to the water bath surface was 8 cm, and the water bath temperature was set to 20°C.

[0415] Then, in order to remove the liquid paraffin from the wound raw filament, it was extracted by immersion in hexane and then dried for 24 hours to obtain the raw filament.

[0416] [Stretching Process]

[0417] The resulting filament is stretched once in a constant temperature bath at 120°C at a speed of 20 mm / min, and then stretched a second time in a constant temperature bath at 140°C at a speed of 10 mm / min until the filament is about to break, thus obtaining high-strength fiber (drawn filament). It should be noted that the temperature in the constant temperature bath is the value obtained by actually measuring the temperature of the center of the constant temperature bath using a thermometer.

[0418] <Manufacturing Method 2 for High-Strength Fibers>

[0419] High-strength fibers were manufactured using ultra-high molecular weight polyethylene (UHMWPE) powder as described below. When the total amount of UHMWPE powder and liquid paraffin was set at 100 parts by weight, 15 parts by weight of UHMWPE powder, 85 parts by weight of liquid paraffin (liquid paraffin manufactured by MORESCO Co., Ltd. (product name: SMOIL P-350P)), and 1 part by weight of antioxidant (tetramethylene (3,5-di-tert-butyl-4-hydroxyhydrocinnamate) methane manufactured by Taiko Chemical Co., Ltd., Japan (product name: ANOX20)) were combined at a point higher than the melting point (T0) of the UHMWPE powder. m2 The liquid was prepared by stirring at a temperature of 35°C for 60 minutes.

[0420] Next, the slurry-like liquid was added to liquid paraffin (liquid paraffin manufactured by MORESCO Co., Ltd. (product name: SMOIL P-350P)) at 180°C and stirred for 2 minutes to produce a gel with a polymer concentration of 5 parts by mass. The resulting gel was then added to a Labo Plastomill (main model: 4C150-01) manufactured by Toyo Seiki Co., Ltd., and mixed at a constant temperature of 150°C for 180 minutes and a screw speed of 10 rpm to produce a mixed gel.

[0421] Next, spinning was performed using a Capillograph 1D (main model: PMD-C) manufactured by Toyo Seiki Co., Ltd. The compounded gel was fed into a furnace set to 180°C using an orifice with a diameter of 1.0 mm, a length of 66 mm, and an inflow angle of 90°, and then degassed for 60 minutes. The extrusion speed was then set to 10 mm / min to achieve an output of 0.45 g / min, and the yarn was wound back at a speed of 0.8 m / min through a water bath immediately below the orifice tip. It should be noted that the distance from the orifice tip to the water bath surface was 8 cm, and the water bath temperature was set to 20°C.

[0422] Then, in order to remove the liquid paraffin from the wound filament, it is extracted by immersing it in hexane and then dried for 24 hours.

[0423] The resulting raw yarn was stretched once in a constant-temperature bath at 120°C at a feed rate of 100 mm / min and a winding rate of 3000 mm / min. Then, it was stretched a second time in a constant-temperature bath at 140°C at a feed rate of 100 mm / min and a winding rate just before the yarn broke, thus obtaining high-strength fiber (drawn yarn). It should be noted that the stretching process was performed using a heated stretching apparatus (main model: IMC-3F08) manufactured by Imoto Manufacturing Co., Ltd. Furthermore, the temperature in the constant-temperature bath was obtained by actually measuring the temperature at the center of the bath using a thermometer.

[0424] <Manufacturing Method 3 for High-Strength Fibers>

[0425] Except for setting the mixing time in the Labo Plastomill (main model: 4C150-01) manufactured by Toyo Seiki Co., Ltd. to 0 minutes (not performing mixing in the Labo Plastomill), the same operation as described above (method 2 for manufacturing high-strength fibers) was performed to obtain high-strength fibers.

[0426] [Gel decomposition rate after mixing]

[0427] The intrinsic viscosity IV of the precursor fiber obtained by the above method is calculated. The intrinsic viscosity of the dried molded product (precursor fiber) is calculated and taken as IV(A). The intrinsic viscosity of the ultra-high molecular weight polyethylene powder before compounding is calculated and taken as IV. The gel decomposition rate is obtained from the calculated intrinsic viscosity IV and intrinsic viscosity IV(A) using the following formula. The gel decomposition rate is evaluated according to the following criteria.

[0428] Calculation of decomposition rate: Decomposition rate = {IV - IV(A)} / IV (Evaluation Criteria) ◎: Decomposition rate greater than or equal to 0% and less than 21% ○: Decomposition rate greater than or equal to 21% and less than 51% △: Decomposition rate greater than or equal to 51% and less than 81% ×: Decomposition rate is above 81% [Tensile breaking strength of high-strength fibers] The 10m high-strength fiber (drawing filament) obtained by spinning using the method described above is cut at 1m intervals. For each of the 10 fibers obtained, it is stretched to break at room temperature, and the average breaking strength is calculated. The breaking strength is then calculated by dividing the highest load applied to the filament by the fineness. Here, fineness refers to the percentage of fibers per × 102 4 The weight (g) of a single filament is determined from the weight of 10m of high-strength fiber. Fineness is expressed in dtex. It should be noted that a scale capable of measuring to the nearest 0.1 mg was used in the weight determination. The tensile breaking strength of the high-strength fiber was evaluated according to the following criteria.

[0429] (Evaluation Criteria)

[0430] ☆: Fracture strength of 43 cN / dtex or higher

[0431] ◎: Fracture strength greater than or equal to 30 cN / dtex and less than 43 cN / dtex

[0432] ○: Fracture strength greater than or equal to 25 cN / dtex and less than 30 cN / dtex

[0433] △: Fracture strength greater than or equal to 20 cN / dtex and less than 25 cN / dtex

[0434] ×: Fracture strength less than 20 cN / dtex

[0435] [Evaluation of the high-speed winding performance of high-strength fibers]

[0436] The gel compounded by the method described above was spun using a Capillograph 1D (main model: PMD-C) manufactured by Toyo Seiki Co., Ltd. A 0.5 mm orifice, 5 mm in length, and 90° inflow angle were used. Regarding the spinning conditions, the temperature was kept constant at 200°C and the extrusion speed at 20 mm / min, while the winding speed was increased from 3 m / min to 19.7 m / min. 2 As the lifting speed gradually increases, the speed at which breakage occurs is measured as the high-speed winding speed. Based on the average of 5 measurements, the following evaluation criteria were used for evaluation.

[0437] (Evaluation Criteria)

[0438] ☆: High-speed winding speed of 900m / min or higher

[0439] ◎: High-speed winding speed greater than or equal to 700 m / min and less than 900 m / min

[0440] ○: High-speed winding speed greater than or equal to 400m / min and less than 700m / min

[0441] △: High-speed winding speed is greater than or equal to 200m / min and less than 400m / min

[0442] ×: High-speed winding speed less than 200m / min

[0443] [Catalyst Synthesis Methods]

[0444] (1) Synthesis of raw material [a-2]

[0445] 2000 mmol of 6[Mg(C4H9)2]·Al(C2H5)3 feedstock [a-1] was added to an 8L stainless steel autoclave after thorough nitrogen purging. After dilution with hexane, 800 mmol of a hexane solution of n-butanol was added dropwise over 3 hours while stirring at 50°C. After the reaction was complete, the pipeline was flushed with 300 mL of hexane. Then, stirring was continued at 50°C for 2 hours. The substance cooled to room temperature was used as feedstock [a-2]. Feedstock [a-2] had a combined magnesium and aluminum concentration of 1.0 mol / L.

[0446] (2) Synthesis of raw material [a-3]

[0447] 2000 mL of [a-1] (equivalent to 2000 mmol based on magnesium and aluminum) was added to an 8L stainless steel autoclave after thorough nitrogen purging. While stirring at 80°C, 240 mL of a hexane solution of 8.33 mol / L methylhydropolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd.) was pressurized and added. The reaction was then continued at 80°C for 2 hours with stirring. After the reaction was completed, the substance cooled to room temperature was used as raw material [a-3]. The total concentration of raw material [a-3] based on magnesium and aluminum was 0.786 mol / L.

[0448] (3) Synthesis of [A-1] vector

[0449] 1000 mL of a 1 mol / L trichlorosilane hexane solution was added to an 8 L stainless steel autoclave after thorough nitrogen purging. A hexane solution of an organomagnesia compound [a-2], equivalent to 943 mmol of magnesium, was added dropwise over 3 hours at 65 °C. The reaction was continued with stirring at 65 °C for 1 hour. After the reaction was complete, the supernatant was removed, and the sample was washed four times with 1800 mL of hexane to obtain the [A-1] support. Analysis of the support revealed that it contained 7.5 mmol of magnesium per 1 g of solid.

[0450] (4) Preparation of catalyst [c-1]

[0451] While stirring at 10°C, 103 mL of a 1 mol / L titanium tetrachloride hexane solution and 131 mL of the raw material [a-3] were simultaneously added to 1970 mL of a hexane slurry containing 110 g of the above-mentioned [A-1] support over 3 hours. After addition, 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, thereby preparing the solid catalyst component [c-1].

[0452] (5) Preparation of catalyst [c-2]

[0453] While stirring at 10°C, 23 mL of a 1 mol / L titanium tetrachloride hexane solution and 29 mL of the raw material [a-3] were simultaneously added over 3 hours to 1970 mL of a hexane slurry containing 110 g of the above-mentioned [A-1] support. After addition, 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. After the reaction was completed, 23 mL of a 1 mol / L triethylaluminum (hereinafter also referred to as TEA) hexane solution was added over 1 hour while stirring at 40°C. After addition, the reaction was continued at 40°C for 1 hour. After the reaction was completed, the supernatant was removed, and the mixture was washed four times with hexane to remove components from the supernatant, thereby preparing the solid catalyst component [c-2].

[0454] (6) Preparation of catalyst [c-3]

[0455] While stirring at 5°C, 103 mL of a 1 mol / L titanium tetrachloride hexane solution and 103 mL of the raw material [a-1] were simultaneously added over 3 hours to 1970 mL of a hexane slurry containing 110 g of the above-mentioned [A-1] support. After addition, the reaction was continued at 5°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. After the reaction was completed, 103 mL of a 1 mol / L ethyl aluminum dichloride (hereinafter also referred to as EADC) hexane solution was added over 1 hour while stirring at 40°C. After addition, the reaction was continued at 40°C for 1 hour. After the reaction was completed, the supernatant was removed and the mixture was washed four times with hexane to remove components from the supernatant, thereby preparing the solid catalyst component [c-3].

[0456] (7) Preparation of catalyst [c-4]

[0457] While stirring at 5°C, 23 mL of a 1 mol / L titanium tetrachloride hexane solution and 23 mL of the raw material [a-1] were simultaneously added over 3 hours to 1970 mL of a hexane slurry containing 110 g of the above-mentioned [A-1] support. After addition, the reaction was continued at 5°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. After the reaction was completed, 23 mL of a 1 mol / L ethyl aluminum dichloride (hereinafter also referred to as EADC) hexane solution was added over 1 hour while stirring at 40°C. After addition, the reaction was continued at 40°C for 1 hour. After the reaction was completed, the supernatant was removed, and the mixture was washed four times with hexane to remove components from the supernatant, thereby preparing the solid catalyst component [c-4].

[0458] The following summarizes the changes made during catalyst synthesis.

[0459] [Table 1]

[0460] (8) Synthesis of co-catalyst [b-2]

[0461] In a 300 mL glass container that had been thoroughly purged with nitrogen, 180 mL of a hexane solution of 1.0 mol / L triisobutylaluminum and diisobutylaluminum hydride (9:1 mixture) [b-1] was added. While stirring at 30 °C, 30 mL of a hexane solution of 1.0 mol / L TEA was added dropwise over 30 minutes. After the addition, the reaction was continued for another 30 minutes. A co-catalyst [b-2] was obtained.

[0462] (9) Synthesis of co-catalyst [b-3]

[0463] In a 300 mL glass container that had been thoroughly purged with nitrogen, 100 mL of a 1.0 mol / L hexane solution of TEA was added. While stirring at 0 °C, 90 mL of a 1.0 mol / L hexane solution of butylated hydroxytoluene was added dropwise over 30 minutes. After the addition, the reaction was continued for another 30 minutes. A large-volume co-catalyst [b-3] was obtained.

[0464] (Example 1)

[0465] Polymerization of Polyethylene Powder

[0466] Polyethylene powder was polymerized using a 1.5L stainless steel autoclave polymerization reactor that had been fully purged with nitrogen, by the method described below.

[0467] First, 800 mL of hexane was added as a solvent to a polymerization reactor heated to 75 °C, along with 0.5 mmol / L of an organometallic compound (b-2) as a co-catalyst. Next, ethylene was added at an internal pressure of 0.397 MPa, followed by hydrogen at an internal pressure of 0.400 MPa. Additionally, 10.0 mg of the aforementioned catalyst [c-4] was added. The internal temperature was maintained at 75 °C, and polymerization was carried out for 90 minutes with stirring at 1000 rpm. During polymerization, the internal pressure was maintained at 0.400 MPa by continuously supplying ethylene. After polymerization, the reaction mixture (polymer slurry) was withdrawn from the polymerization reactor, and the catalyst was deactivated using methanol. The polymer slurry was filtered through a 500-mesh sieve (26 μm mesh size) to obtain polyethylene powder. The obtained polyethylene powder was dried at 40 °C for 24 hours. The polymerization activity in the polymerization reactor was 6000 g relative to 1 g of catalyst.

[0468] Scaling and extremely coarse powder were removed using a sieve with a mesh size of 425 μm, and the physical properties of the polyethylene powder were evaluated.

[0469] The results obtained by performing the above-described evaluations on polyethylene powder (A) and the fibers of polyethylene powder (A) manufactured by the above-described <Manufacturing Methods 1 to 3 of High Strength Fibers> are shown in Table 3.

[0470] (Examples 2 to 15 and Comparative Examples 1, 2, and 4)

[0471] Except for the changes in polymerization conditions shown in Tables 2 and 4, polyethylene powder and its fibers were manufactured in the same manner as in Example 1, and the various evaluations described above were performed. The results are shown in Tables 3 and 5. It should be noted that in Examples 14 and 15, 1-butene was copolymerized as a comonomer (denoted as "CM" in the table).

[0472] (Example 16)

[0473] Polymerization of Polyethylene Powder (B)

[0474] Hexane, ethylene, and catalyst were continuously fed into a 300L trough-type (vessel type) polymerization reactor equipped with three swept-back agitator blades and three baffles. The polymerization pressure was 0.4 MPa. The polymerization temperature was maintained at 60°C by jacket cooling. Hexane was supplied from the bottom of the polymerizer at a rate of 40 L / h, with an average residence time of 120 min. Catalyst [c-3] was used as the polymerization catalyst and supplied at a production rate of 10.0 kg / h for polyethylene powder. Co-catalyst [b-1] (a mixture of triisobutylaluminum and diisobutylaluminum hydride (9:1)) was used as the co-catalyst component and supplied at a rate of 10 mmol / h. No hydrogen was supplied. STATSAFE 3000 diluted with n-hexane (90 g / L) was added to the polymerization catalyst at an amount of 25 ppm by mass relative to the production rate of polyethylene powder. The stirring speed was set to 230 rpm.

[0475] The polymerization slurry in the polymerization reactor was introduced into an intermediate flash tank at a pressure of 0.05 MPaG and a temperature of 40°C to maintain a constant liquid level in the polymerization reactor and to separate unreacted ethylene. The polymerization slurry was continuously pumped from the flash tank to a centrifuge to separate the polymer from the solvent. The separated polyethylene powder was then fed to a rotary kiln dryer controlled at 70°C, where it was dried while being purged with nitrogen. It should be noted that during this drying process, vapor was sprayed onto the polyethylene powder, thereby deactivating the catalyst and co-catalyst. The resulting polyethylene powder was then sieved using a 425 μm mesh to remove any material that did not pass through the sieve, thus obtaining the polyethylene powder. The polymerization activity in the polymerization reactor was 21,000 g relative to 1 g of catalyst.

[0476] The results are shown in Tables 4 and 5.

[0477] (Comparative Example 3)

[0478] Preparation of catalyst [c-5]

[0479] Prepolymerization of 20 g of catalyst [c-1] was carried out in a 1.5 L autoclave. 800 mL of n-hexane was used as the solvent, and 0.4 mmol of [b-1] (a mixture of triisobutylaluminum and diisobutylaluminum hydride (9:1)) was used as the co-catalyst, with 20 mol% (molar ratio: hydrogen / (ethylene + hydrogen)) of hydrogen supplied. The polymerization temperature was set at 20 °C, and ethylene was supplied at a rate of 5 g of polyethylene per 1 g of catalyst [c-1]. After polymerization, the supernatant was removed, and the mixture was washed four times with hexane to remove unreacted raw materials, thus preparing catalyst [c-5].

[0480] Polyethylene powder was polymerized in a 300L trough-type polymerization reactor equipped with three swept-back agitator blades and three baffles. Hexane was supplied as solvent at a flow rate of 40 L / h, and the total liquid volume was adjusted to a slurry concentration of 30% by mass. The stirring speed was set to 550 rpm. Ziegler-Natta catalyst [c-5] was used as the polymerization catalyst and supplied at a polyethylene powder production rate of 9 kg / h. STATSAFE 3000 diluted with hexane (90 g / L) was added to the polymerization catalyst at an amount of 20 ppm by mass relative to the polyethylene powder production rate. [b-1] (a mixture of triisobutylaluminum and diisobutylaluminum hydride (9:1)) was used as the co-catalyst component and supplied at a rate of 10 mmol / h. 1.0 mol% (molar ratio: hydrogen / (ethylene + hydrogen)) of hydrogen was supplied. The polymerization temperature was set to 78 °C, the polymerization pressure to 0.3 MPaG, and the average residence time to 3.0 h. The polymerization slurry in the polymerization reactor is introduced into a flash tank at a pressure of 0.05 MPaG and a temperature of 70°C to maintain a constant liquid level in the reactor and separate unreacted ethylene and hydrogen. Next, the polymerization slurry is continuously pumped from the flash tank to a centrifuge to separate the polymer from the solvent. The separated polyethylene powder is then conveyed to a rotary kiln dryer controlled at 90°C, where it is dried while nitrogen is being blown in. It should be noted that during this drying process, vapor is sprayed onto the polyethylene powder, thereby deactivating the catalyst and co-catalyst.

[0481] The results are shown in Tables 4 and 5.

[0482] [Table 2]

[0483] [Table 3]

[0484] [Table 4]

[0485] [Table 5]

[0486] Industrial practicality

[0487] The polyethylene powder of the present invention has industrial applicability as a raw material for various molded bodies, microporous membranes, battery separators, and fibers.

Claims

1. An ultra-high molecular weight polyethylene powder, wherein, The intrinsic viscosity IV of the ultra-high molecular weight polyethylene powder is 12.0 dL / g or more and 35.0 dL / g or less, The mobility index of the ultra-high molecular weight polyethylene powder calculated from the following (Formula I) is 57 milliseconds or more and 73 milliseconds or less, [Mobility index] = Tα x Rα / (Rα + Rβ) + Tβ x Rβ / (Rα + Rβ) (Formula I) [In Formula I, Tα is the relaxation time (milliseconds) of the component α having low mobility, Rα is the presence ratio of the component α having low mobility, Tβ is the relaxation time (milliseconds) of the component β having intermediate mobility, Rβ is the presence ratio of the component β having intermediate mobility, The Tα, Rα, Tβ, and Rβ are values obtained by approximating a free induction decay curve obtained using a pulse NMR and utilizing a Carr Purcell Meiboom Gill method into three components of the component α having low mobility, the component β having intermediate mobility, and the component γ having high mobility].

2. The ultra-high molecular weight polyethylene powder according to claim 1, wherein The entanglement degree of the ultra-high molecular weight polyethylene powder calculated from the following (Formula II) is 0.6 or more and 2.8 or less, [Entanglement degree] = Rβ / Rα (Formula II) [In Formula II, Rβ and Rα are as described in Claim 1].

3. The ultra-high molecular weight polyethylene powder according to claim 1 or 2, wherein The ultra-high molecular weight polyethylene powder satisfies the following (Formula III) relationship, [Formula III] [Mobility index] > -0.2 x [Intrinsic viscosity IV] + 62.

4. The ultra-high molecular weight polyethylene powder according to claim 1 or 2, wherein By 13 The content of the structural unit derived from the olefin capable of copolymerizing with ethylene of the ultra-high molecular weight polyethylene powder measured by C-NMR is 0.1 mol% or less.

5. The ultra-high molecular weight polyethylene powder according to claim 1 or 2, wherein The D50 of the ultra-high molecular weight polyethylene powder measured using a laser diffraction type particle size distribution measuring device is 40 μm or more and 400 μm or less.

6. The ultra-high molecular weight polyethylene powder according to claim 1 or 2, wherein The intrinsic viscosity IV of the ultra-high molecular weight polyethylene powder is 17.0 dL / g or more and 33.0 dL / g or less.

7. The ultra-high molecular weight polyethylene powder according to claim 1 or 2, wherein The mobility index of the ultra-high molecular weight polyethylene powder is 64 milliseconds or more and 73 milliseconds or less.

8. The ultra-high molecular weight polyethylene powder according to claim 1 or 2, wherein, The content of titanium (Ti) of the ultra-high molecular weight polyethylene powder is 10 ppm or less, and the content of aluminum (Al) is 10 ppm or less.

9. The ultra-high molecular weight polyethylene powder according to claim 1 or 2, wherein, The ultra-high molecular weight polyethylene powder is used for a high-strength fiber.

10. A shaped body, wherein, The molded body is a molded body of the ultra-high molecular weight polyethylene powder described in Claim 1 or 2.

11. The shaped body of claim 10, wherein, The molded body is a fiber.

12. A method of manufacturing high-strength fibers, wherein, The method for manufacturing the high-strength fiber has the following steps: a slurry step in which an ultra-high molecular weight polyethylene powder and a first liquid paraffin are mixed, and the mixture is stirred at a temperature below the melting point of the ultra-high molecular weight polyethylene powder to obtain a slurry, a gelation step in which the slurry and a second liquid paraffin at 150°C or higher and 300°C or lower are mixed to obtain a gel for a precursor filament at 140°C or higher and 200°C or lower, an extrusion step in which the gel for a precursor filament is extruded to obtain a precursor filament, an extraction step in which the first liquid paraffin and the second liquid paraffin are extracted from the precursor filament to obtain a precursor filament for stretching, and a precursor filament stretching step in which the precursor filament for stretching is heat stretched, The intrinsic viscosity IV of the ultra-high molecular weight polyethylene powder is 12.0 dL / g or more and 35.0 dL / g or less, The ultrahigh molecular weight polyethylene powder has a mobility index of 57 milliseconds or more and 73 milliseconds or less, calculated from the following formula (I), [Formula I] [Mobility Index] = Tα x Rα / (Rα + Rβ) + Tβ x Rβ / (Rα + Rβ) [In formula I, Tα is the relaxation time (milliseconds) of the component α having low mobility, Rα is the presence ratio of the component α having low mobility, Tβ is the relaxation time (milliseconds) of the component β having intermediate mobility, Rβ is the presence ratio of the component β having intermediate mobility, The Tα, Rα, Tβ, and Rβ are values obtained by approximating a free induction decay curve obtained using a pulse NMR and utilizing a Carr Purcell Meiboom Gill method into three components of the component α having low mobility, the component β having intermediate mobility, and the component γ having high mobility].

13. The method of manufacturing high-strength fibers according to claim 12, wherein, The extrusion process is preceded by a kneading process in which the gel for the original yarn is kneaded.

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