Polyphenylene ether fiber, activated carbon fiber, and method for producing polyphenylene ether fiber

Abstract

The purpose of the present invention is to provide a PPE fiber with excellent lightweight properties, and an activated carbon fiber using the PPE fiber as raw cotton. Another purpose of the present invention is to provide a method for producing a PPE fiber, the method making it possible to suppress single yarn breakage and efficiently produce a PPE fiber with excellent lightweight properties. The present invention relates to a polyphenylene ether fiber containing a polyphenylene ether component, and having an average number of cells of 1 or more per 1 mm2 in a cross-section of the polyphenylene ether fiber, a single yarn fineness of 100 dtex or less, and a viscosity of 0.50 dl / g or less. The present invention further relates to a method for producing a polyphenylene ether fiber, the method comprising: a step for melt-extruding a polyphenylene ether, which is a starting material, using an extruder equipped with a cylinder and a screw; and a step for discharging the molten polyphenylene ether from a spinning nozzle and spinning the polyphenylene ether, wherein degassing is not performed in the melt-extruding step.

Description

Polyphenylene ether fibers, activated carbon fibers, and methods for producing polyphenylene ether fibers

[0001] The present invention relates to polyphenylene ether fibers, activated carbon fibers, and a method for producing polyphenylene ether fibers.

[0002] Polyphenylene ether (hereinafter sometimes referred to as "PPE") has excellent heat resistance, flame retardancy, strength, and chemical resistance, and molded articles formed from polyphenylene ether are used in a wide range of fields. Known molded articles formed from polyphenylene ether include polyphenylene ether melt-spun fibers and fabrics and nonwovens formed from these fibers (for example, Patent Document 1).

[0003] International Publication No. 2021 / 060210

[0004] Patent Document 1 shows that melt-molding is possible even when PPE is used alone or in high concentrations, and that PPE melt-spun fibers with excellent properties such as mechanical strength can be provided.

[0005] When PPE fibers are manufactured by melt spinning, gas is generated when the PPE is melted. Therefore, a method of degassing the gas generated during the melt extrusion process is usually employed. If the gas is not degassed during the melt extrusion process of PPE, the gas can cause bubbles to form in the PPE fibers, leading to single-fiber breakage during melt spinning and other issues that result in poor spinability.

[0006] Furthermore, depending on the intended use of PPE fibers, lightweight properties were sometimes required, but conventional PPE fibers had not been adequately considered in terms of weight reduction.

[0007] Therefore, an object of the present invention is to provide PPE fibers that are lightweight (i.e., have a low specific gravity), and activated carbon fibers using said PPE fibers as raw material. Furthermore, another object of the present invention is to provide a method for producing PPE fibers that can suppress single-fiber breakage and efficiently produce PPE fibers that are lightweight.

[0008] As a result of intensive studies, the inventors of the present invention have found that the above problems can be solved by having a fine fiber diameter and containing a certain amount of air bubbles, and have completed the present invention.

[0009] That is, the present invention is a polyphenylene ether fiber containing a polyphenylene ether component, wherein the average number of air bubbles in the cross-section of the polyphenylene ether fiber is 1 or more per 1 mm ２ or more, the fineness is 100 dtex or less, and the viscosity is 0.50 dL / g or less, and relates to a polyphenylene ether fiber.

[0010] The polyphenylene ether fiber preferably has a maximum stress of 1.0 cN / dtex or more and a maximum elongation of 40% or more.

[0011] The polyphenylene ether fiber preferably has a single fiber fineness of 30 dtex or less.

[0012] The polyphenylene ether component preferably has a dislocation structure connected by an ortho-position bond in a repeating unit continuously bonded by a para-position bond.

[0013] The repeating unit continuously bonded by the para-position bond is represented by the following general formula (1): (In the formula, R １ , R ２ are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, and R ３ are each independently a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent), and the dislocation structure is represented by the following general formula (2): (In the formula, R １ , R ２ are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, and R ３ are each independently a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, and R ３ ' represents a divalent group obtained by removing one hydrogen atom from the above R ３ ), and is preferably a structure represented by the formula.

[0014] It is preferable that the amount of rearrangement in the polyphenylene ether component having the rearrangement structure is 0.05 mol% or more relative to the total polyphenylene ether structural units in the polyphenylene ether component.

[0015] It is preferable that the content of the polyphenylene ether component is 95% by mass or more of the total components forming the fiber.

[0016] Furthermore, the present invention relates to activated carbon fibers characterized by using the aforementioned polyphenylene ether fibers as raw material.

[0017] Furthermore, the present invention relates to a method for producing polyphenylene ether fibers, comprising the steps of melting and extruding a raw material, polyphenylene ether, using an extruder equipped with a cylinder and a screw, and spinning the molten polyphenylene ether by extruding it from a spinning nozzle, characterized in that degassing is not performed in the melting and extruding step.

[0018] It is preferable that the viscosity of the aforementioned raw material, polyphenylene ether, is 0.42 dL / g or less.

[0019] It is preferable to introduce an inert gas at 100°C or higher directly below the spinning nozzle.

[0020] The present invention provides PPE fibers that are lightweight (i.e., have a low specific gravity), activated carbon fibers using said PPE fibers as raw material, and a method for producing PPE fibers that can suppress single-fiber breakage and efficiently produce lightweight PPE fibers.

[0021] The manufacturing method of the present invention is characterized by not performing degassing in the melt extrusion process. By not performing degassing, the resulting PPE fibers contain a certain amount of air bubbles, which in turn allows for weight reduction of the product.

[0022] This is a schematic cross-sectional view showing one embodiment of the method for producing PPE fibers according to the present invention.

[0023] 1. PPE Fibers The PPE fibers of the present invention contain PPE components, and the average number of air bubbles in the cross-section of the PPE fibers is 1 mm ２It is characterized in that there is one or more per unit, the fineness is 100 dtex or less, and the viscosity is 0.50 dL / g or less.

[0024] The PPE fiber of the present invention has an average number of air bubbles in the cross-section of the PPE fiber of 1 per 1 mm ２ Since there is one or more per unit, the weight of the fiber can be reduced. From the viewpoint of weight reduction, the number of air bubbles is preferably 2 or more, more preferably 6 or more, and even more preferably 10 or more. Also, the number of air bubbles is preferably 100 or less, more preferably 80 or less, even more preferably 70 or less, still more preferably 50 or less, and particularly preferably 30 or less.

[0025] The PPE fiber of the present invention has a viscosity of 0.50 dL / g or less. Usually, when air bubbles are generated in the spinning process, yarn breakage may occur starting from the air bubbles. This is because the smaller the fineness of the fiber, the greater the influence of the air bubbles, and there is a tendency for yarn breakage to occur. In the present invention, by setting the viscosity of the PPE fiber to 0.50 dL / g or less, even if air bubbles are generated, the fineness of the PPE fiber can be set to 100 dtex or less. The viscosity is more preferably 0.48 dL / g or less, and even more preferably 0.46 dL / g or less. The viscosity is the viscosity measured at 30 °C, and the measurement can be performed by the method described in the examples.

[0026] The PPE fiber of the present invention preferably has a maximum stress of 0.8 cN / dtex or more, and more preferably 0.9 cN / dtex or more. The upper limit is not particularly limited, but is preferably 10 cN / dtex or less.

[0027] The maximum elongation of the PPE fiber of the present invention is preferably 25% or more, more preferably 30% or more, and even more preferably 40% or more. The upper limit is not particularly limited, but is preferably 250% or less.

[0028] The glass transition temperature of the PPE fiber of the present invention is preferably 170°C or higher, more preferably 175°C or higher, and even more preferably 180°C or higher. Having the glass transition temperature within this range provides extremely high heat resistance. While there is no particular upper limit, from the viewpoint of moldability, it is preferably 300°C or lower, and more preferably 250°C or lower.

[0029] The specific gravity of the PPE fiber of the present invention is not particularly limited, but from the viewpoint of weight reduction, it is 1.00 to 1.20 g / cm³. ３ Preferably, 1.05 to 1.18 g / cm³ ３ This is preferable.

[0030] The PPE fibers of the present invention may also be short fibers. These short fibers can be obtained, for example, by cutting fibers that have been formed into a tow by splicing PPE fibers together.

[0031] The single filament fineness of the PPE fiber is 100 dtex or less, preferably 90 dtex or less, more preferably 80 dtex or less, and even more preferably 70 dtex or less. The lower limit of the single filament fineness is not particularly limited, but for example, 1 dtex or more is preferred, and 2 dtex or more is more preferred. Having the single filament fineness within the above range is preferable because it gives the fiber good processability.

[0032] The following describes the PPE components contained in the PPE fibers of the present invention.

[0033] <PPE components> The PPE components are not particularly limited and include those commonly used in this field. Specifically, the following general formula (1): (In the formula, R １ , R ２ Each is independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, which may have substituents, and R ３ Examples include homopolymers having repeating units represented by (wherein each of them independently represents a hydrocarbon group having 1 to 10 carbon atoms which may have substituents), copolymers containing two or more different repeating units of general formula (1), and copolymers having repeating units of general formula (1) and repeating units other than general formula (1).

[0034] In the above general formula (1), R １ ~R ３ Examples of hydrocarbon groups having 1 to 10 carbon atoms include alkyl groups having 1 to 10 carbon atoms such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, octyl, and decyl groups; aryl groups having 6 to 10 carbon atoms such as phenyl, 4-methylphenyl, 1-naphthyl, and 2-naphthyl groups; and aralkyl groups having 7 to 10 carbon atoms such as benzyl, 2-phenylethyl, and 1-phenylethyl groups.

[0035] If the hydrocarbon group has substituents, examples of substituents include halogen atoms such as fluorine atoms, and alkoxy groups such as methoxy groups. Specific examples of hydrocarbon groups with substituents include, for example, trifluoromethyl groups.

[0036] Among these, R １ , R ２ As for the hydrogen atom, a methyl group is preferred, and a hydrogen atom is more preferred, R ３ A methyl group is preferred as the component.

[0037] Specific examples of the repeating unit of the general formula (1) include repeating units derived from 2,6-dimethyl-1,4-phenylene ether, 2,6-diethyl-1,4-phenylene ether, 2-methyl-6-ethyl-1,4-phenylene ether, and 2,6-dipropyl-1,4-phenylene ether. Among these, the repeating unit derived from 2,6-dimethyl-1,4-phenylene ether is preferred.

[0038] Furthermore, the PPE may contain repeating units other than those of general formula (1) as long as it does not impair the effects of the present invention. The content of such repeating units other than those of general formula (1) is not particularly limited as long as it does not impair the effects of the present invention, but for example, it is preferably about 5 mol% or less in the copolymer, and more preferably it is not included.

[0039] The PPE component preferably has a dislocation structure connected by ortho bonds within a repeating unit that is continuous by para bonds. Examples of the repeating unit that is continuous by para bonds include the repeating unit represented by the above general formula (1), and examples of the dislocation structure include the following general formula (2): (In the formula, R １ , R ２ Each is independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, which may have substituents, and R ３ Each is independently a hydrocarbon group having 1 to 10 carbon atoms, which may have substituents, and R ３ ' is the aforementioned R ３ One possible rearrangement structure is represented by (representing a divalent group from which one hydrogen atom has been removed).

[0040] In the above general formula (2), R １ ~R ３ Examples include those similar to those in general formula (1) above. The "~" in general formula (2) indicates that the structure beyond it is not particularly limited. The "~" portion may be formed from phenylene ether units connected by para bonds, or it may have a portion that is partially bonded at the ortho position.

[0041] The aforementioned R ３ ' is the aforementioned R ３ This represents a divalent group from which one hydrogen atom has been removed, and it is preferably a methylene group.

[0042] The PPE component having the aforementioned rearrangement structure is preferably a homopolymer having repeating units of general formula (1), a copolymer containing two or more different repeating units of general formula (1), or a copolymer containing repeating units of general formula (1) and repeating units other than general formula (1) that has a rearrangement structure represented by general formula (2).

[0043] If the PPE component has a dislocation structure, the amount of the dislocation structure (hereinafter also referred to as "dislocation amount") is preferably 0.05 mol% or more, preferably 0.1 mol% or more, and more preferably 0.15 mol% or more, relative to the total structural units constituting the PPE component. Furthermore, the dislocation amount is preferably 15 mol% or less, more preferably 10 mol% or less, and even more preferably 8 mol% or less. Having the dislocation amount in the PPE component having a dislocation structure within the above range is preferable because it allows for obtaining a melt viscosity suitable for spinning.

[0044] The aforementioned dislocation structure is observed in the nuclear magnetic resonance spectrum ( １ In 1H-NMR measurements, it is preferable to show peaks in the ranges of 3.8–4.0 ppm and 6.8–7.0 ppm. Typically, PPE shows a peak around 6.4–6.6 ppm, which is a peak originating from the hydrogen atoms at positions 3 and 5 of the benzene ring in the PPE main chain. PPE having the rearrangement structure shows peaks in the ranges of 3.8–4.0 ppm and 6.8–7.0 ppm, in addition to the peak around 6.4–6.6 ppm. The chemical shift at 3.8–4.0 ppm is due to R in the rearrangement structure. ３’ This originates from the proton of the divalent group (e.g., methylene group) shown, and the chemical shift of 6.8 to 7.0 ppm is due to the R at the 3 and 5 positions of PPE in the rearrangement structure. １ , R ２ It originates from the protons of the group (for example, the hydrogen atoms at positions 3 and 5 of the benzene ring bonded to the ortho position via a methylene group).

[0045] The molecular weight of the PPE is not particularly limited, but it is preferably 40,000 to 100,000 in weight-average molecular weight (Mw), and more preferably 50,000 to 80,000. The number-average molecular weight (Mn) is preferably 7,000 to 30,000, and more preferably 8,000 to 20,000. The molecular weight dispersion (Mw / Mn) is preferably 3.5 to 8.0, and more preferably 4.0 to 6.0.

[0046] The PPE component content is preferably 95% by mass or more of the total components forming the PPE fiber, more preferably 98% by mass or more, and even more preferably substantially composed of only PPE components (100% by mass). Having the PPE component content in the PPE fiber within the above range is preferable because it not only provides excellent mechanical strength to the resulting fiber, but also excellent heat resistance, chemical resistance, flame retardancy, etc.

[0047] <Components other than PPE components> The PPE fiber of the present invention may contain resin components other than the PPE components. Examples of resin components other than PPE components include styrene, polyethylene, polypropylene, polyamides such as polyamide 4, polyamide 6, polyamide 10, polyamide 11, polyamide 66, polyamide 6T, polyamide 6T / 11, polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polycarbonates. However, the content of these components is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably none (0% by mass).

[0048] Furthermore, the PPE fibers of the present invention may also contain additives such as lubricants, plasticizers, antioxidants, ultraviolet absorbers, dulling agents, and antistatic agents, to the extent that they do not impair the effects of the present invention.

[0049] The PPE fibers of the present invention are preferably manufactured by the PPE fiber manufacturing method described below.

[0050] 2. Activated Carbon Fibers The activated carbon fibers of the present invention are obtained using the PPE fibers as raw material. Specifically, the PPE fibers are treated in at least one step selected from a process consisting of infusibility treatment (for example, heat treatment at 120 to 400°C for 0.1 to 100 hours in an air atmosphere with a water vapor concentration of 0.5 to 20 vol.%) and carbonization treatment, and the resulting fibers are then activated.

[0051] The activated carbon fibers of the present invention can be suitably used in applications such as water purification, air purification, gas adsorption, water treatment, and various filters such as canisters.

[0052] 3. Method for Manufacturing PPE Fibers The method for manufacturing PPE fibers according to the present invention includes the steps of melting and extruding polyphenylene ether, which is a raw material, using an extruder equipped with a cylinder and a screw, and spinning the molten polyphenylene ether by extruding it from a spinning nozzle, characterized in that no degassing is performed in the melting and extruding step.

[0053] An example of manufacturing PPE melt-spun fibers will be explained using Figure 1. The raw material, PPE, is fed from the hopper 1 in Figure 1 into an extruder 2 equipped with a cylinder and screw. The molten PPE is discharged at a rate measured by a gear pump 3, passes through a filter material 4 composed of fine sand or the like, and is discharged from a spinning nozzle 5 to obtain melt-spun fibers. The extruder may be equipped with a degassing vent 10 as shown in Figure 1, but if it is equipped, it must be used with the degassing vent 10 closed. Furthermore, it is preferable to install a filter 6 made of a metal nonwoven fabric or the like on the filter material 4. Installing a filter 6 is preferable because it can remove foreign matter in advance and prevent clogging of the filter material 4.

[0054] Furthermore, it is preferable to provide a heat retention space 7 directly below the spinning nozzle 5 and introduce an inert gas such as nitrogen 8 into this area during spinning, from the viewpoint of suppressing nozzle clogging due to oxidative crosslinking, and it is even more preferable to introduce a heated inert gas using a heating torch 9.

[0055] The temperature of the heated inert gas is preferably 50°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher. While there is no particular upper limit, for example, it is preferably 500°C or lower, more preferably 400°C or lower, even more preferably 300°C or lower, and particularly preferably 200°C or lower. Using an inert gas at the above temperature allows for a wider deformation range of the resulting PPE fiber, thereby improving spinnability.

[0056] Examples of the aforementioned inert gases include noble gases such as helium, neon, argon, and krypton, as well as nitrogen gas. Among these, nitrogen gas is preferred.

[0057] The spinning speed is not particularly limited and can be set appropriately according to the required fineness, etc., but in order to stably obtain fine fibers, a speed of about 100 m / min or more is preferred, and about 200 m / min or more is more preferred. Furthermore, a speed of about 5000 m / min or less is preferred, and about 4000 m / min or less is more preferred.

[0058] The single-hole discharge rate of the spinning nozzle is preferably 3.0 g / min or less, more preferably 2.8 g / min or less, and even more preferably 2.6 g / min or less. The lower limit of the single-hole discharge rate is not particularly limited, but is preferably 0.05 g / min or more, more preferably 0.1 g / min or more, and even more preferably 0.12 g / min or more.

[0059] Examples of PPE used as a raw material include homopolymers having the repeating unit of general formula (1), copolymers containing two or more different repeating units of general formula (1), and copolymers having the repeating unit of general formula (1) and repeating units other than general formula (1). The content of repeating units other than general formula (1) in the copolymer can be as described above. Among these, homopolymers having the repeating unit of general formula (1) are preferred.

[0060] Examples of homopolymers having the repeating unit of the general formula (1) include poly(2,6-dimethyl-1,4-phenylene ether), poly(2,6-diethyl-1,4-phenylene ether), poly(2-methyl-6-ethyl-1,4-phenylene ether), and poly(2,6-dipropyl-1,4-phenylene ether), but among these, poly(2,6-dimethyl-1,4-phenylene ether) is preferred.

[0061] Commercially available poly(2,6-dimethyl-1,4-phenylene ether) products can also be suitably used. Specifically, examples include PPO640, PPO646, and PPOSA120 from SABIC Innovative Plastic, Xylon S201A and Xylon S202A from Asahi Kasei Chemicals Corporation, and LXN035 from Bluestar.

[0062] The viscosity of the PPE raw material is preferably 0.42 dL / g or less, more preferably 0.41 dL / g or less, and even more preferably 0.40 dL / g or less, from the viewpoint of spinnability and weight reduction. The viscosity is the viscosity measured at 30°C, and can be measured by the method described in the examples.

[0063] Furthermore, when melting PPE, the melt viscosity can be reduced by mixing PPE with high Tg and low Tg.

[0064] The glass transition temperature of the PPE component having a high glass transition temperature is preferably 170°C or higher, more preferably 200°C or higher, and even more preferably 210°C or higher. Furthermore, while there is no particular upper limit to the glass transition temperature, 230°C or lower is preferred. Having the glass transition temperature of the raw material PPE within this range is preferable because it allows for the acquisition of PPE fibers with high heat resistance.

[0065] The glass transition temperature of the PPE component having a low glass transition temperature is preferably less than 170°C. Adding PPE with a glass transition temperature of less than 170°C reduces the melt viscosity and improves fluidity.

[0066] The content of PPE having a glass transition temperature of 170°C or higher is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, in the PPE component of the raw material. Furthermore, there is no particular upper limit to the content of PPE having a glass transition temperature of 170°C or higher, but it is preferably 100% by mass or less. In the present invention, including PPE with a high glass transition temperature (i.e., high molecular weight) within the above range is preferable because it results in excellent mechanical strength, heat resistance, chemical resistance, flame retardancy, etc., of the resulting PPE molten fibers.

[0067] Furthermore, along with the raw material PPE, the material may also contain resin components and additives other than PPE. The resin components and additives other than PPE are as described above. The content of resin components other than PPE is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably none (0% by mass).

[0068] As the extruder equipped with the cylinder and screw, a single-screw extruder or a twin-screw extruder, which are commonly used in this field, can be used. In the present invention, it is preferable to use a twin-screw extruder.

[0069] The peripheral speed of the screw is not particularly limited and can be within the range commonly used in this field. However, when forming fibers using a PPE component having a dislocation structure, the peripheral speed of the screw must be such that the dislocation reaction of the raw material PPE occurs, and is preferably 3.6 m / min or more, more preferably 3.7 m / min or more, and even more preferably 3.8 m / min or more. Furthermore, the upper limit of the peripheral speed of the screw is not particularly limited, but is preferably 94.2 m / min or less. In the present invention, by increasing the screw rotation speed to 3.6 m / min or more, a high shear force can be applied to the raw material PPE in the cylinder, and as a result, the molecular chains of PPE can be cut, and PPE having a dislocation structure can be formed. The formation of the PPE having a dislocation structure makes melt spinning of PPE possible.

[0070] If the temperature inside the cylinder is too low, the fluidity of the resin will be poor, and if it is too high, although the fluidity will improve, foaming will occur due to thermal decomposition of the resin. Therefore, it is necessary to select a processing temperature that strikes a balance between these two factors. For example, the temperature inside the cylinder is preferably between 250°C and 350°C, and more preferably between 280°C and 330°C.

[0071] The surface temperature of the spinning nozzle is not particularly limited, but is preferably 300°C or higher, more preferably 320°C or higher, and even more preferably 330°C or higher. A nozzle surface temperature within this range is preferable because it results in fluidity suitable for spinning.

[0072] According to the manufacturing method of the present invention, PPE fibers with a specific number of bubbles can be obtained by not performing degassing in the melt extrusion process.

[0073] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The evaluation methods for physical properties, etc., in the following examples are as follows.

[0074] (1) Fineness and single filament fineness were measured according to the method described in JIS L-1095 9.4.1. Single filament fineness was calculated by dividing the fineness by the number of filaments.

[0075] (2) Glass transition temperature (Tg) Using a differential scanning calorimetry analyzer (model: DSC-Q100) manufactured by TA Instruments Inc., 2 mg of PPE fiber was measured from 30°C to 250°C in a nitrogen atmosphere at a heating rate of 10°C / min. The temperature at the intersection of the extension of the baseline below the glass transition temperature and the tangent line showing the maximum slope in the transition region was defined as the glass transition temperature (Tg).

[0076] (3) The amount of dislocation structure in PPE fibers at a resonance frequency of 600 MHz １ The measurement was performed using 1H-NMR. A BRUKER NMR spectrometer (model name: AVANCE-NEO600) was used, and the measurement was performed as follows: 10 mg of PPE fiber obtained in the examples and comparative examples was dissolved in deuterated chloroform, and the solution was packed into an NMR tube within 2 hours for measurement. Deuterated chloroform was used as the locking solvent, with a waiting time of 1 second, a data acquisition time of 4 seconds, and 64 integration cycles. Deuterated benzene may also be used as the solvent. The rearrangement structure amount was analyzed as follows: R at the 3 and 5 positions of PPE. １ , R ２ Peaks originating from the proton of the base and R in the dislocation structure ３ The peak integrals of the peaks originating from the protons of the divalent group (methylene group, etc.) indicated by ' were denoted as A and B, and the rearrangement structure weight was calculated using the following formula: Rearrangement structure weight (mol%) = (B / (A + B)) × 100

[0077] (4) Viscosity of raw material PPE and PPE fibers A 0.5 g / dL solution was prepared by dissolving 0.125 g of raw material PPE or obtained PPE fibers in 25 ml of chloroform, filtering it through a filter paper and glass filter, and then measuring the viscosity at 30°C using an Ubbelohde viscometer with a viscometer constant of 0.003.

[0078] (5) Average number of bubbles Cut 100 PPE multifilaments and observe the cross-section with an optical microscope (BX53M: manufactured by OLYMPUS) and count the number of bubbles in the fiber cross-section, 1 mm ２ Converted to a number per unit. Average number of bubbles = Number of bubbles in the cross-section of 100 fibers / Cross-sectional area of ​​100 fibers (mm²) ２ )

[0079] (6) Stress and elongation at the maximum point were measured in accordance with JIS L1013 8.5.1. The stress at the maximum load was defined as the stress at the maximum point, and the elongation rate at the maximum load was defined as the elongation at the maximum point.

[0080] (7) Peripheral speed of the screw The peripheral speed of the screw was determined by the following formula: Peripheral speed of the screw (m / min) = Screw diameter (mm) × 0.00314 × Screw rotation speed (rpm)

[0081] Example 1 Poly(2,6-dimethyl-1,4-phenylene ether) (LXN035, glass transition temperature (Tg): 213°C, viscosity: 0.37 dL / g, manufactured by Bluestar) was extruded using a single-screw extruder. The single-screw extruder had four cylinder zones, which were designated as cylinders 1, 2, 3, and 4 from the hopper side. Cylinder 1 was set to 260°C, cylinders 2-4 and the cylinder head were set to 280°C, and the screw rotation speed was set to 5 rpm, resulting in a screw peripheral speed of 0.47 m / min. Cylinder 3 was fitted with a vent, but the vent was closed and no degassing was performed.

[0082] Downstream of the extruder, a gear pump was installed, and the polymer was extruded through a metal nonwoven fabric filter (product name: NF-07, manufactured by Nippon Seisen Co., Ltd.) to a nozzle (nozzle hole diameter: 0.5 mm, nozzle hole land length: 2.0 mm, number of nozzle holes: 24) (total discharge volume: 13.8 g / min). Nitrogen gas at 150°C was introduced directly below the nozzle. The polymer discharged from the nozzle was wound up at a spinning speed of 261 m / min.

[0083] Example 2 PPE fibers were obtained in the same manner as in Example 1, except that the spinning speed was changed to 575 m / min.

[0084] Example 3 Poly(2,6-dimethyl-1,4-phenylene ether) (LXN035, glass transition temperature (Tg): 213°C, viscosity: 0.37 dL / g, manufactured by Bluestar) was extruded using a twin-screw extruder manufactured by Technovel Co., Ltd. (product name: KZW15TW-30MG). The twin-screw extruder had four cylinder zones, and the cylinders from the hopper side were designated as cylinder 1, 2, 3, and 4. Cylinder 1 was set to 260°C, and cylinders 2-4 and the cylinder head were set to 300°C. The screw rotation speed was set to 700 rpm, and the peripheral speed of the screw was set to 33 m / min. A vent was attached to cylinder 3, but the vent was closed and no degassing was performed.

[0085] Downstream of the extruder, a gear pump was installed, and the polymer was extruded through a metal nonwoven fabric filter (product name: NF-07, manufactured by Nippon Seisen Co., Ltd.) to a nozzle (nozzle hole diameter: 0.5 mm, nozzle hole land length: 2.5 mm, number of nozzle holes: 24) (total discharge rate: 13 g / min). Nitrogen gas at 150°C was introduced directly below the nozzle. The polymer discharged from the nozzle was wound up at a spinning speed of 246 m / min.

[0086] Example 4: PPE fibers were obtained in the same manner as in Example 3, except that the screw rotation speed was changed to 400 rpm.

[0087] Comparative Example 1: In forming PPE fibers, the raw material was changed to poly(2,6-dimethyl-1,4-phenylene ether) (PPO (trademark registered) 640, glass transition temperature (Tg): 221°C, viscosity: 0.43 dL / g, manufactured by SABIC Innovative Plastic) and the nitrogen gas temperature was changed to 30°C. PPE fibers were obtained in the same manner as in Example 1.

[0088] Comparative Example 2: In forming PPE fibers, the raw material was changed to poly(2,6-dimethyl-1,4-phenylene ether) (PPO (trademark registered) 640, glass transition temperature (Tg): 221°C, viscosity: 0.43 dL / g, manufactured by SABIC Innovative Plastic) and the nitrogen gas temperature was changed to 30°C. PPE fibers were obtained in the same manner as in Example 3.

[0089] Comparative Example 3: In forming PPE fibers, the raw material was changed to poly(2,6-dimethyl-1,4-phenylene ether) (PPO (trademark registered) 640, glass transition temperature (Tg): 221°C, viscosity: 0.43 dL / g, manufactured by SABIC Innovative Plastic), cylinders 2-4 and the cylinder head were set to 330°C, the nozzle was changed to one with a nozzle hole diameter of 1.3 mm, a nozzle hole land length of 7.8 mm, and 48 nozzle holes, the total discharge rate was changed to 66 g / min, the spinning speed to 1375 m / min, and degassing was performed with the vent open. PPE fibers were obtained in the same manner as in Example 3.

[0090] Comparative Example 4: PPE fibers were obtained in the same manner as in Comparative Example 3, except that the spinning speed was changed to 625 m / min and the vent was opened to perform degassing.

[0091] Comparative Example 5: In forming PPE fibers, the total discharge rate was changed to 50 g / min, the cylinder head temperature to 350°C, and the spinning speed to 1042 m / min. Except for degassing by vacuuming the vent, PPE fibers were obtained in the same manner as in Example 4.

[0092] Comparative Example 6: PPE fibers were obtained in the same manner as in Comparative Example 5, except that the spinning speed was changed to 473 m / min.

[0093]

[0094] Examples 1 to 4 all have a fineness of 100 dtex or less, and an average number of air bubbles in the fiber cross-section of 1 / 1 mm. ２ The PPE fibers described above were obtained. In all cases, the time until single filament breakage was 15 minutes or more, indicating that single filament breakage was suppressed. On the other hand, in Comparative Examples 1 and 2, the viscosity of the PPE fibers was high, and during spinning, air bubbles became the starting point for yarn breakage. In Comparative Examples 3 to 6, the vent was open or vacuumed, and no PPE fibers with air bubbles were obtained.

[0095] 1. Hopper 2. Extruder 3. Gear pump 4. Filter media 5. Spinning nozzle 6. Filter 7. Insulated space 8. Inert gas introduction 9. Heating torch 10. Degassing vent

Claims

1. A polyphenylene ether fiber containing a polyphenylene ether component, wherein the average number of air bubbles in the cross-section of the polyphenylene ether fiber is 1 mm ２ A polyphenylene ether fiber characterized by having one or more particles per unit, a single filament fineness of 100 dtex or less, and a viscosity of 0.50 dL / g or less.

2. The polyphenylene ether fiber according to claim 1, characterized in that the maximum point stress is 1.0 cN / dtex or more and the maximum point elongation is 40% or more.

3. The polyphenylene ether fiber according to claim 1, characterized in that the single filament fineness is 30 dtex or less.

4. The polyphenylene ether fiber according to claim 1, characterized in that the polyphenylene ether component has a rearrangement structure in which it is connected by ortho bonds in a repeating unit that is continuous by para bonds.

5. The repeating units that are continuous with the para-position bonds are represented by the following general formula (1): (In the formula, R １ , R ２ are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, and R ３ each independently represents a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent), and the rearrangement structure is represented by the following general formula (2): (In the formula, R １ , R ２ are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, R ３ are each independently a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, and R ３ ' represents a divalent group obtained by removing one hydrogen atom from the above R ３ ). The polyphenylene ether fiber according to claim 4, characterized in that it has the structure represented by the formula.

6. The polyphenylene ether fiber according to claim 4, characterized in that the amount of dislocation in the polyphenylene ether component having the dislocation structure is 0.05 mol% or more relative to the total polyphenylene ether structural units in the polyphenylene ether component.

7. The polyphenylene ether fiber according to claim 1, characterized in that the content of the polyphenylene ether component is 95% by mass or more of the total components forming the fiber.

8. An activated carbon fiber characterized by using polyphenylene ether fibers according to any one of claims 1 to 7 as raw cotton.

9. A method for producing polyphenylene ether fibers according to any one of claims 1 to 7, comprising the steps of melting and extruding polyphenylene ether, which is a raw material, using an extruder equipped with a cylinder and a screw, and discharging the molten polyphenylene ether from a spinning nozzle and spinning it, wherein degassing is not performed in the melting and extruding step.

10. The method for producing polyphenylene ether fibers according to claim 9, characterized in that the viscosity of the polyphenylene ether, which is the raw material, is 0.42 dL / g or less.

11. The method for producing polyphenylene ether fibers according to claim 9, characterized in that an inert gas at 100°C or higher is introduced directly below the spinning nozzle.

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