Polyphenylene ether fiber, activated carbon fiber, and method of manufacturing polyphenylene ether fiber

Abstract

The purpose of the present invention is to provide PPE fibers in which fiber-diameter unevenness in the fiber length direction is controlled to a minimum, and activated carbon fibers employing the PPE fibers as a raw cotton. Furthermore, another purpose of the present invention is to provide a PPE-fiber manufacturing method by which PPE fibers can be efficiently manufactured over long periods while preventing hindrances, such as thread breakage during spinning, from occurring over long periods. The present invention relates to polyphenylene ether fibers containing polyphenylene ether components, the polyphenylene ether fibers being characterized in that the Uster index (URI) value is less than 33.1%. Also, the present invention relates to a polyphenylene ether fiber manufacturing method characterized by including: a step of melt-extruding polyphenylene ether, which is the raw material, by using an extruder equipped with a cylinder, a screw, and a degassing vent, while degassing the raw material through the degassing vent; and a step of pumping the molten polyphenylene ether through a spinning nozzle to be spun.

Description

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

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

[0002] Polyphenylene ether (hereinafter sometimes referred to as "PPE") has excellent heat resistance, flame retardancy, strength, chemical resistance, etc., 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 nonwoven fabrics formed from the 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 the case of a high PPE content, and that it is possible to provide PPE melt-spun fibers with excellent properties such as mechanical strength. However, it has now become clear that when melt-spinning is carried out over a long period of time, yarn breakage may occur during spinning, and that this is insufficient in terms of operational stability (long-term stability).

[0005] As a result of investigating this point, it was newly discovered that when the melt-spun fiber is stretched and deformed on the nozzle surface during spinning, unevenness in the fiber diameter occurs in the longitudinal direction of the fiber, and single fiber breakage occurs when the fiber becomes thinner.

[0006] Therefore, an object of the present invention is to provide a PPE fiber in which the occurrence of fiber diameter unevenness in the fiber longitudinal direction is suppressed, and an activated carbon fiber using such a PPE fiber as raw fiber. Furthermore, another object of the present invention is to provide a method for producing a PPE fiber that can efficiently produce a PPE fiber over a long period of time without problems such as yarn breakage during spinning.

[0007] As a result of extensive research, the inventors discovered that by modifying the PPE component, the occurrence of uneven fiber diameter in the longitudinal direction of the fiber can be suppressed, thereby solving the above-mentioned problem, and thus completed the present invention.

[0008] That is, the present invention relates to a polyphenylene ether fiber containing a polyphenylene ether component, characterized in that the polyphenylene ether fiber has a Worcester (URI) value of less than 33.1%.

[0009] The molecular configuration parameter α of the polyphenylene ether component in the Mark-Houwink-Sakurada equation is preferably less than 0.7.

[0010] The weight retention when the temperature is raised from 100°C to 350°C is preferably 99.20% or more.

[0011] The polyphenylene ether component preferably has a rearrangement structure in which repeating units connected by a bond at the para position are connected by a bond at the ortho position.

[0012] The repeating units connected consecutively via the para-position bond 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 a repeating unit 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’ is the R ３ It is preferable that the structure is a divalent group in which one hydrogen atom has been removed from the group

[0013] The amount of rearrangements in the polyphenylene ether component having the rearrangement structure is preferably 0.05 mol % or more based on the total polyphenylene ether structural units in the polyphenylene ether component.

[0014] The content of the polyphenylene ether component is preferably 95% by mass or more of all components forming the fiber.

[0015] The polyphenylene ether fiber preferably has a single filament fineness of 1.0 dtex or more and 100 dtex or less.

[0016] The present invention also relates to activated carbon fibers, characterized in that the polyphenylene ether fibers are used as raw fibers.

[0017] Furthermore, the present invention relates to a method for producing polyphenylene ether fibers, comprising: a step of melt-extruding a raw material polyphenylene ether using an extruder equipped with a cylinder, a screw, and a degassing vent while degassing the raw material polyphenylene ether through the degassing vent; and a step of discharging the molten polyphenylene ether from a spinning nozzle and spinning the molten polyphenylene ether.

[0018] The raw material polyphenylene ether preferably contains polyphenylene ether having a glass transition temperature of 170° C. or higher.

[0019] The surface temperature of the spinning nozzle is preferably 300°C or higher.

[0020] The ratio (L / D) of the diameter D to the length L of the spinning nozzle is preferably 3 or more and 10 or less.

[0021] The peripheral speed of the screw is preferably 3.6 m / min or more.

[0022] The present invention can provide PPE fibers in which the occurrence of unevenness in fiber diameter in the fiber longitudinal direction is suppressed, activated carbon fibers using the PPE fibers as raw cotton, and a method for producing PPE fibers that does not cause problems such as yarn breakage during spinning over a long period of time and that can efficiently produce PPE fibers over a long period of time.

[0023] The manufacturing method of the present invention is characterized by degassing through a degassing vent during the melt extrusion process to reduce low-molecular-weight components, including low-molecular-weight PPE components. By reducing the low-molecular-weight PPE components, rearrangement reactions of the PPE components occur through reactions between high-molecular-weight PPE molecular chains, resulting in a molecular structure with long branched chains, which is thought to cause the molecular chains to become more spherical. This spherical shape makes it easier for the molecular chains to catch on each other during elongation deformation, increasing strain hardening and facilitating tension application to the yarn during spinning. As a result, it is thought that the occurrence of fiber diameter unevenness in the longitudinal direction of the resulting PPE fiber is suppressed. Furthermore, PPE fibers can be efficiently produced without problems such as yarn breakage during spinning. While it is well known that adding a low-molecular-weight plasticizer typically improves processability, in the present invention, reducing the low-molecular-weight component improves long-term processability, which is thought to be due to a unique phenomenon.

[0024] 1 is a cross-sectional view schematically showing one embodiment of a method for producing PPE fibers of the present invention.

[0025] 1. PPE Fiber The PPE fiber of the present invention is characterized by containing a polyphenylene ether component and having a Worcester (URI) value of less than 33.1%.

[0026] The URI value is an index of fiber diameter unevenness in the longitudinal direction of the fiber. The URI value of the PPE fiber of the present invention is less than 33.1%, preferably 30% or less, more preferably 25% or less, even more preferably 20% or less, and particularly preferably 15% or less. The smaller the URI value, the better, with the lower limit being 0%. In the present invention, when the URI value of the PPE fiber is less than 33.1%, the fiber diameter unevenness in the longitudinal direction of the PPE fiber is reduced, the occurrence of yarn breakage during spinning is suppressed, and operational stability is excellent. The URI value can be measured by the method described in the examples.

[0027] 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. A glass transition temperature within this range can impart very high heat resistance. There is no particular upper limit, but from the viewpoint of moldability, it is preferably 300°C or lower, more preferably 250°C or lower.

[0028] The PPE fiber of the present invention may be a staple fiber, which can be obtained, for example, by cutting a tow formed by doubling PPE fibers.

[0029] The single filament fineness of the PPE fiber is not particularly limited and can be appropriately determined depending on the purpose for which the fiber is used. For example, the single filament fineness is preferably 1 dtex or more and 100 dtex or less, more preferably 1.2 dtex or more and 60 dtex or less, and even more preferably 1.5 dtex or more and 40 dtex or less.

[0030] The content of low-molecular-weight PPE components in the PPE fibers is preferably 600 ppm or less, more preferably 500 ppm or less, based on the total amount of the PPE fibers. Here, the low-molecular-weight PPE components refer to PPE components with a molecular weight of 400 or less.

[0031] The weight retention of the PPE fiber when heated from 100° C. to 350° C. is preferably 99.20% or more, more preferably 99.25% or more, and even more preferably 99.30% or more. A weight retention within the above range indicates that the content of low-molecular-weight PPE components contained in the PPE fiber is low, and is therefore preferred.

[0032] The PPE component contained in the PPE fiber of the present invention will be described below.

[0033] <PPE Component> The PPE component is not particularly limited, and examples thereof include those commonly used in this field. Specifically, PPE components 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, R ３each independently represent a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent), or a copolymer containing two or more different repeating units of general formula (1), or a copolymer having a repeating unit of general formula (1) and a repeating unit other than the repeating unit of general formula (1).

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

[0035] When the hydrocarbon group has a substituent, examples of the substituent include a halogen atom such as a fluorine atom, an alkoxy group such as a methoxy group, etc. Specific examples of the hydrocarbon group having a substituent include a trifluoromethyl group, etc.

[0036] Among these, R １ , R ２ is preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom, and R ３ As the alkyl group, a methyl group is preferred.

[0037] Specific examples of the repeating unit of 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 the effects of the present invention are not impaired. The content of such repeating units other than those of general formula (1) is not particularly limited as long as the effects of the present invention are not impaired, but for example, it is preferably about 5 mol % or less in the copolymer, and more preferably no repeating units are contained.

[0039] The PPE component preferably has a rearrangement structure in which repeating units connected by a bond at the para position are connected by a bond at the ortho position. Examples of the repeating units connected by a bond at the para position include the repeating unit represented by the above general formula (1), and examples of the rearrangement structure include the repeating unit 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 ' is the R ３ and represents a divalent group in which one hydrogen atom has been removed from the group

[0040] R in the general formula (2) １ ~R ３ Examples of the phenylene ether unit include those similar to those in the general formula (1). The "~" in the general formula (2) indicates that the structure following it is not particularly limited. The "~" portion may be formed from consecutive phenylene ether units linked via para-bonds, and may also contain portions partially linked at the ortho position.

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

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

[0043] When the PPE component has a rearrangement structure, the amount of the rearrangement structure (hereinafter also referred to as "rearrangement amount") is preferably 0.05 mol% or more, preferably 0.1 mol% or more, and more preferably 0.5 mol% or more, relative to the total structural units constituting the PPE component. The rearrangement amount is preferably 15 mol% or less, more preferably 10 mol% or less, and even more preferably 8 mol% or less. When the rearrangement amount in the PPE component having a rearrangement structure is within the above range, it is believed that the number of bent structures increases, and the molecular chain tends to approach a spherical shape, which reduces the spread of the molecular chain and tends to increase strain hardening, which is preferable.

[0044] The rearrangement structure can be identified by nuclear magnetic resonance spectroscopy ( １ In H-NMR measurement, it is preferable that the PPE exhibits peaks in the range of 3.8 to 4.0 ppm and in the range of 6.8 to 7.0 ppm. Usually, PPE exhibits peaks in the vicinity of 6.4 to 6.6 ppm, which are peaks derived from the hydrogen atoms at the 3rd and 5th positions of the benzene ring in the PPE main chain. The PPE having the rearrangement structure exhibits peaks in the range of 3.8 to 4.0 ppm and in the range of 6.8 to 7.0 ppm, in addition to the peak in the vicinity of 6.4 to 6.6 ppm. The chemical shift in the range of 3.8 to 4.0 ppm is derived from the R in the rearrangement structure. ３’ The chemical shift in the range of 6.8 to 7.0 ppm is due to the protons of the divalent group (for example, a methylene group) represented by the formula: １ , R ２ These are derived from protons of the group (for example, hydrogen atoms at the 3- and 5-positions of a benzene ring bonded via a methylene group at the ortho-position).

[0045] The molecular conformation parameter α of the PPE component is preferably less than 0.7, more preferably 0.695 or less, and even more preferably 0.690 or less. The lower limit of the molecular conformation parameter α is not theoretically limited, but is typically 0.01 or more. The molecular conformation parameter α is an index representing the state of polymer molecules in solution; a smaller value indicates a more spherical structure, and a larger value indicates a more rod-like structure. In other words, for polymers of the same composition, a smaller value is considered to indicate a greater number of branched and bent structures that are advantageous for strain hardening. Having the molecular conformation parameter α within the above range is preferable because it results in a structure that is advantageous for strain hardening, reduces fiber diameter unevenness in the longitudinal direction of the PPE fiber, and improves spinning stability. Although the molecular conformation parameter α is due to the dislocation structure, it is not determined solely by the amount of dislocation structure, but is also determined by the structural state, such as the branched and bent structure of the polymer chain, depending on the position of the dislocation structure, etc. Here, the molecular shape parameter α is the Mark-Houwink-Sakurada equation ([η] = K M) that is established between the intrinsic viscosity [η] and the molecular weight (M). α , K is a coefficient), the intrinsic viscosity is determined from the slope of a double logarithmic plot with the logarithm of the molecular weight on the horizontal axis and the logarithm of the intrinsic viscosity on the vertical axis. In the present invention, the intrinsic viscosity is determined from the slope of a double logarithmic plot with the logarithm of the weight-average absolute molecular weight (Mw) on the horizontal axis and the logarithm of the intrinsic viscosity on the vertical axis.

[0046] The weight-average absolute molecular weight (Mw) of the PPE component is preferably 10,000 g / mol or more, more preferably 20,000 g / mol or more, even more preferably 30,000 g / mol or more, and particularly preferably 35,000 g / mol or more. The weight-average absolute molecular weight (Mw) is preferably 150,000 g / mol or less, more preferably 100,000 g / mol or less, and even more preferably 80,000 g / mol or less. Setting the weight-average absolute molecular weight (Mw) within the above range is preferable from the viewpoint of heat resistance. Here, the weight-average absolute molecular weight (Mw) refers to the true weight-average molecular weight of the polymer. The weight-average molecular weight measured by conventional gel permeation chromatography (GPC) is a relative weight-average molecular weight determined using a standard polymer such as linear polystyrene having a known molecular weight. When a branched structure is present in the polymer, the molecular weight may not be accurately evaluated. The weight-average absolute molecular weight (Mw) is measured using a GPC apparatus equipped with a specified column and a multi-angle light scattering detector, and can accurately measure molecular weight without being affected by polymer structures such as branched structures. The weight-average absolute molecular weight (Mw) can be measured by the method described in the Examples below. This weight-average absolute molecular weight (Mw) is different from the weight-average (relative) molecular weight obtained by conventional GPC methods, which is calculated using a polystyrene-equivalent value (relative value).

[0047] The number-average absolute molecular weight (Mn) of the PPE component is preferably 8,000 g / mol or more, more preferably 9,000 g / mol or more, and even more preferably 10,000 g / mol or more. The number-average absolute molecular weight (Mn) is preferably 100,000 g / mol or less, more preferably 80,000 g / mol or less, and even more preferably 70,000 g / mol or less. Setting the number-average absolute molecular weight (Mn) within the above range is preferable from the viewpoint of heat resistance. Here, the number-average absolute molecular weight (Mn) is the true number-average molecular weight of the polymer, and, like the weight-average absolute molecular weight (Mw), it is measured using a GPC apparatus equipped with a specified column and a multi-angle light scattering detector. This number-average absolute molecular weight (Mn) is different from the number-average (relative) molecular weight obtained using conventional GPC methods, which is calculated using a polystyrene-equivalent value (relative value).

[0048] The absolute molecular weight dispersity (weight average absolute molecular weight (Mw) / number average absolute molecular weight (Mn)) of the PPE component is preferably 5.0 or less, more preferably 4.5 or less, and even more preferably 4.0 or less. Mw / Mn is 1 or more. As Mw / Mn increases, the glass transition peak tends to become broader. Therefore, from the viewpoint of quality, it is preferable to set it in the above range.

[0049] The relative molecular weight of the PPE component is not particularly limited, but the weight-average relative molecular weight (Mw') is preferably 40,000 to 100,000, and more preferably 50,000 to 80,000. The number-average relative molecular weight (Mn') is preferably 7,000 to 30,000, and more preferably 8,000 to 20,000. The relative molecular weight dispersity (Mw' / Mn') is preferably 2.5 to 8.0, and more preferably 2.8 to 6.0.

[0050] The content of the PPE component is preferably 95% by mass or more, more preferably 98% by mass or more, and even more preferably substantially composed of only the PPE component (100% by mass) of all the components forming the PPE fiber. When the content of the PPE component in the PPE fiber is within the above range, the obtained fiber not only has excellent mechanical strength, but also excellent heat resistance, chemical resistance, flame retardancy, etc., and is therefore preferred.

[0051] <Components Other Than the PPE Component> The PPE fiber of the present invention may contain a resin component other than the PPE component. Examples of resin components other than the PPE component include styrene, polyethylene, polypropylene, polyamides such as polyamide 4, polyamide 6, polyamide 10, polyamide 11, polyamide 66, polyamide 6T, and polyamide 6T / 11, polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polycarbonates. However, the content of such components is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably zero (0% by mass).

[0052] Furthermore, additives such as lubricants, plasticizers, antioxidants, ultraviolet absorbers, dulling agents, and antistatic agents may also be added to the PPE fibers of the present invention, provided that the effects of the present invention are not impaired.

[0053] The PPE fiber of the present invention is preferably produced by the method for producing PPE fiber described below.

[0054] 2. Activated Carbon Fiber The activated carbon fiber of the present invention uses the PPE fiber as a raw fiber. Specifically, the activated carbon fiber can be obtained by treating the PPE fiber in at least one step selected from the group consisting of an infusible treatment (for example, a heat treatment at 120 to 400°C for 0.1 to 100 hours in an air atmosphere having a water vapor concentration of 0.5 to 20 vol.%) and a carbonization treatment, and then activating the resulting fiber.

[0055] The activated carbon fiber of the present invention can be suitably used for applications such as water purification, air purification, gas adsorption, water treatment, and various filters for canisters.

[0056] 3. Manufacturing Method of PPE Fiber The manufacturing method of PPE fiber of the present invention is characterized by comprising: a step of melt-extruding a raw material polyphenylene ether using an extruder equipped with a cylinder, a screw, and a degassing vent while degassing it through the degassing vent; and a step of discharging the molten polyphenylene ether from a spinning nozzle and spinning it.

[0057] An example of the production of PPE melt-spun fibers will be described using FIG. 1. The raw material PPE is fed from a hopper 1 shown in FIG. 1 into an extruder 2 equipped with a cylinder, a screw, and a degassing vent 10. The molten PPE is metered at a discharge rate using a gear pump 3, passes through a filter medium 4 made of fine sand, and is discharged from a spinning nozzle 5 to obtain melt-spun fibers. The extruder may be equipped with an inert gas or a vacuum pump at the end of the degassing vent 10 to prevent oxygen from entering the extruder 2. It is also preferable to install a filter 6 made of a metal nonwoven fabric or the like on the filter medium 4. Installing the filter 6 is preferable because it allows foreign matter to be removed in advance and prevents clogging of the filter medium 4.

[0058] It is also preferable to provide a heat-retaining space 7 directly below the spinning nozzle 5 and introduce an inert gas such as nitrogen into this space 8 from the viewpoint of preventing nozzle clogging due to oxidative crosslinking, and it is more preferable to introduce an inert gas heated by a heating torch 9. The temperature of the heated inert gas is preferably 100°C or higher and 500°C or lower, more preferably 200°C or higher and 400°C or lower.

[0059] The degassing vent 10 may be an open vent with nothing attached to the end, or may be a vacuum vent connected to a vacuum pump for active degassing by suction. When vacuum venting is performed, a trap for collecting volatile components may be provided between the vent and the vacuum pump. In the present invention, a vacuum vent is preferred from the viewpoint of reducing low-molecular-weight PPE components in the extrusion composition.

[0060] The spinning speed is not particularly limited and can be set appropriately depending on the desired fineness, etc., but in order to stably obtain fine fibers, it is preferably about 100 m / min or more, more preferably about 200 m / min or more, and is preferably about 5000 m / min or less, more preferably about 4000 m / min or less.

[0061] The output rate per hole 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 output rate per hole 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.

[0062] The ratio (L / D) of the diameter D to the length L of the spinning nozzle is preferably 3 or more and 20 or less, more preferably 4 or more and 10 or less. When the ratio of the diameter D to the length L of the spinning nozzle is in the above range, the pressure loss in the orifice portion is appropriately applied, which is preferable from the viewpoint of uniform distribution.

[0063] Examples of the PPE raw material include a homopolymer having a repeating unit of the general formula (1), a copolymer containing two or more different repeating units of the general formula (1), and a copolymer having a repeating unit of the general formula (1) and a repeating unit other than the general formula (1). The content of the repeating unit other than the general formula (1) in the copolymer can be as described above. Among these, a homopolymer having a repeating unit of the general formula (1) is preferred.

[0064] Specific examples of the homopolymer having the repeating unit of 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). Among these, poly(2,6-dimethyl-1,4-phenylene ether) is preferred.

[0065] As the poly(2,6-dimethyl-1,4-phenylene ether), commercially available products can also be suitably used. Specific examples include PPO640, PPO646, and PPOSA120 manufactured by SABIC Innovative Plastics, and ZYLON S201A and ZYLON S202A manufactured by Asahi Kasei Chemicals Corporation.

[0066] Furthermore, when melting PPE, it is possible to lower the melt viscosity by mixing PPE having a high Tg and PPE having a low Tg.

[0067] 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. There are no particular limitations on the upper limit of the glass transition temperature, but it is preferably 230° C. or lower. Having the glass transition temperature of the raw material PPE within this range is preferred because it allows the production of PPE fibers with high heat resistance.

[0068] The glass transition temperature of the PPE component having a low glass transition temperature is preferably less than 170° C. By adding a PPE having a glass transition temperature of less than 170° C., the melt viscosity is reduced and the flowability is improved.

[0069] The content of the PPE having a glass transition temperature of 170°C or higher is preferably 70% by mass or higher, more preferably 80% by mass or higher, and even more preferably 90% by mass or higher, in the raw PPE component. The upper limit of the content of the PPE having a glass transition temperature of 170°C or higher is not particularly limited, but is preferably 100% by mass or lower. In the present invention, it is preferred to include a PPE having a high glass transition temperature (i.e., a high molecular weight) in the above range, since the resulting PPE molten fiber will have excellent mechanical strength, heat resistance, chemical resistance, flame retardancy, etc.

[0070] In addition, resin components and additives other than the PPE component may be contained in addition to the raw material PPE. The resin components and additives other than the PPE component are as described above. The content of resin components other than the PPE component in the raw material is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably 0% by mass or less.

[0071] The extruder equipped with the cylinder, screw, and degassing vent may be a single-screw extruder or a twin-screw extruder that is commonly used in this field. In the present invention, it is preferable to use a twin-screw extruder.

[0072] The screw peripheral speed 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 rearrangement structure, the screw peripheral speed must be such that the rearrangement reaction of the raw material PPE occurs, and is preferably 3.6 m / min or higher, more preferably 3.7 m / min or higher, and even more preferably 3.8 m / min or higher. The upper limit of the screw peripheral speed is not particularly limited, but is preferably 94.2 m / min or lower. In the present invention, by increasing the screw rotation speed to a screw peripheral speed of 3.6 m / min or higher, high shear force can be applied to the raw material PPE in the cylinder, resulting in scission of the molecular chains of the PPE and the formation of PPE having a rearrangement structure. The formation of PPE having the rearrangement structure makes melt spinning of PPE possible.

[0073] If the temperature inside the cylinder is too low, the fluidity of the resin will be poor, and if it is too high, the fluidity will be improved but foaming will occur due to thermal decomposition of the resin, so it is necessary to select a processing temperature that strikes a balance between these two. The temperature inside the cylinder is, for example, preferably 250°C or higher and 350°C or lower, and more preferably 280°C or higher and 330°C or lower.

[0074] 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. Having the nozzle surface temperature in this range is preferable because it provides fluidity suitable for spinning.

[0075] According to the manufacturing method of the present invention, degassing is performed through a degassing vent during the melt extrusion process to reduce low-molecular-weight PPE components, which is thought to cause a rearrangement reaction of PPE between high-molecular-weight PPE molecular chains, resulting in a molecular structure with long branched chains and making the molecular chains more spherical. As a result, the molecular chains of the resulting PPE fiber are more likely to catch on each other during elongation deformation, increasing strain hardening and making it easier to apply tension to the yarn during spinning, resulting in PPE fiber with reduced fiber diameter unevenness in the fiber longitudinal direction. Therefore, the manufacturing method of the present invention prevents problems such as yarn breakage during spinning over the long term, allowing for efficient long-term production of PPE fiber and improving long-term stability.

[0076] 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 these examples. The physical properties and other properties in the following examples were evaluated using the following methods.

[0077] (1) Fineness, Single Yarn Fineness Measured by the method described in JIS L-1095 9.4.1. The single yarn fineness was calculated by dividing the fineness by the number of filaments.

[0078] (2) Maximum stress and maximum elongation were measured according to JIS L-1013 8.5.1. The stress at the maximum load was defined as the maximum stress, and the elongation at the maximum load was defined as the maximum elongation.

[0079] (3) Glass Transition Temperature (Tg) Using a differential scanning calorimeter (model: DSC-Q100) manufactured by TA Instruments Inc., 2 mg of PPE fiber was measured in a nitrogen atmosphere from 30°C to 250°C at a heating rate of 10°C / min, and the temperature at the intersection of an extension of the baseline below the glass transition temperature and a tangent line showing the maximum slope at the transition portion was taken as the glass transition temperature (Tg).

[0080] (4) Amount of dislocation structure in PPE fiber Resonance frequency 600 MHz １ The measurement was carried out by H-NMR measurement. The measurement device used was a BRUKER NMR device (device name: AVANCE-NEO600), and the measurement was carried out as follows. 10 mg of the PPE fibers obtained in the examples and comparative examples were dissolved in deuterated chloroform, and the solution was filled into an NMR tube within 2 hours and the measurement was carried out. Deuterated chloroform was used as the lock solvent, the waiting time was 1 second, the data acquisition time was 4 seconds, and the number of accumulations was 64. Deuterated benzene may also be used as the solvent. The analysis of the amount of rearrangement structure was carried out as follows. The R at the 3rd and 5th positions of PPE was １ , R ２ The peaks due to the protons of the R group and the R ３’ The peak integral values ​​of the peaks derived from the protons of the divalent group (e.g., methylene group) represented by the formula: A and B, respectively, and the amount of rearranged structure was calculated by the following formula: Amount of rearranged structure (mol %)=(B / (A+B))×100

[0081] (5) Number of Single Yarn Breakage Spinning was carried out under the conditions described above, and the number of single yarn breakages that occurred within one hour from the start of winding was counted and evaluated as the number of yarn breakages per hour.

[0082] (6) URI Value Measurement was performed using a Worster Evenness Tester 5 manufactured by Zellweger Worster. The measurement was performed with a sensor length of 1.4 m. A slot was selected depending on the fineness of the multifilament, and measurements were performed for 2 minutes at a yarn speed of 50 m / min while twisting the yarn at a twist rate of 4000 turns / min. The maximum value of the chart obtained was A (%) and the minimum value was B (%). The URI value was calculated using the following formula: URI value (%) = A - B

[0083] (7) Weight Retention Rate Measurement was performed using a simultaneous thermogravimetric differential thermal analyzer (device name: TG / DTA7200) manufactured by SII Nanotechnology, Inc. Approximately 10 mg of the obtained PPE fiber was precisely weighed into an aluminum pan, and an empty aluminum pan was used as a reference. The temperature was raised from 30°C at a rate of 10°C / min under a nitrogen atmosphere, and the weight at 100°C was defined as A (mg) and the weight at 350°C as B (mg), and the weight retention rate was calculated using the following formula: Weight retention rate (%) = B / A x 100

[0084] (8) Molecular Weight Measurement (8-1) Absolute Molecular Weight The number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw / Mn) in absolute molecular weight were all determined using gel permeation chromatography (GPC). The measurement conditions were as follows: Apparatus: OMNISEC RESOLVE (manufactured by Spectris Inc.) Detector: OMNISEC REVEAL (differential refractive index detector, light scattering detector, viscosity detector, manufactured by Spectris Inc.) Column: TSKgel Super HM-H manufactured by Tosoh Corporation (two columns connected in series) Solvent: Chloroform Temperature: 40°C Flow rate: 0.6 mL / min Measurement solution sample concentration: 1.0 mg / mL Injection volume: 20 μL (8-2) Relative Molecular Weight The number average molecular weight (Mn'), weight average molecular weight (Mw'), and molecular weight dispersity (Mw' / Mn') in terms of relative molecular weight in terms of polystyrene were measured under the same conditions as in "(8) Absolute Molecular Weight" above, and a differential refractive index detector was used as the detector. The standard polystyrenes used to prepare the calibration curve are as follows: Standard sample: monodisperse polystyrene "Waters Polystyrene Standard (peak MW=2698)" "Shodex STANDARD SM-105 (S-3.37, S-13.9, S-30.3, S-52.4, S-205, S-696, S-1110, S-2210, S-3740)" Samples were prepared by dissolving 5 mg of the PPE fibers obtained in the examples and comparative examples in 5 mL of chloroform.

[0085] (9) Molecular Conformation Parameter α The molecular conformation parameter α in the Mark-Houwink-Sakurada equation, which is established between intrinsic viscosity and molecular weight, was determined from the slope of a double logarithmic plot, with the logarithm of the weight-average absolute molecular weight (Mw) obtained by the above-mentioned measurement method on the horizontal axis and the logarithm of the intrinsic viscosity on the vertical axis. The analysis range was set to a range in which the signal-to-noise ratio at the base of each detected peak was 3 or more.

[0086] (10) Quantitation of low-molecular-weight PPE components: Quantitation of low-molecular-weight PPE components was performed using a pyrolysis gas chromatograph (Py-GC / MS). 2 mg of the obtained PPE fiber was placed in a sample cup for Py-GC / MS analysis, and analysis was performed under the following conditions. (Py-GC / MS analysis conditions) Apparatus: PY-2020iD (Frontier LAB) / QP-2010Plus (Shimadzu) Sample heating conditions: 320°C x 10 min Carrier / heating atmosphere gas: He Column: Ultra ALLOY-5 (MS / HT) (length 30 m, inner diameter 0.25 mm, film thickness 0.25 μm) (Frontier LAB) Column oven temperature: 40°C (2 min) - 10°C / min - 300°C (15 min) Injection port pressure: 80 kPa Injection port temperature: 320°C Split ratio: 30 Ion source: EI method Ion source temperature: 250°C Ionization voltage: 70 eV Interface temperature: 320°C MS measurement mode: SCAN Mass measurement range: m / z 30-550. Quantitative values ​​were calculated by conversion quantitation using octamethylcyclotetrasiloxane as a standard substance. The ratio of low-molecular-weight polyphenylene ether components was calculated from the sum of the peaks corresponding to 2,6-dimethylphenol and its oligomers (dimer and trimer).

[0087] (11) Peripheral speed of screw The peripheral speed of the screw was calculated by the following formula: Peripheral speed of screw (m / min) = screw diameter (mm) × 0.00314 × screw rotation speed (rpm)

[0088] Example 1 Poly(2,6-dimethyl-1,4-phenylene ether) (PPO (registered trademark) 640, glass transition temperature (Tg): 221°C, manufactured by SABIC Innovative Plastics) was extruded using a twin-screw extruder (product name: KZW15TW-30MG) manufactured by Technovel Corporation. The twin-screw extruder had four cylinder zones, and from the hopper side, the cylinders were designated as cylinders 1, 2, 3, and 4. Cylinder 1 was set to 280°C, and cylinders 2 to 4 and the cylinder head were set to 300°C. The screw rotation speed was set to 700 rpm, and the screw peripheral speed was 33.0 m / min. A vent was attached to cylinder 3, and the outlet was purged with nitrogen.

[0089] A gear pump was installed downstream of the extruder, and the polymer was extruded through a metal nonwoven filter (product name: NF-07, manufactured by Nippon Seisen Co., Ltd.) into a nozzle (nozzle hole diameter: 0.80 mm, nozzle hole land length: 4.0 mm, number of nozzle holes: 48) (total extrusion rate: 13.1 g / min). The polymer extruded from the nozzle was wound at a spinning speed of 546 m / min. The obtained fiber had a URI value of 10.6%, a molecular conformation parameter α of 0.629, a weight retention at 350 °C of 99.40%, and a low molecular weight polyphenylene ether component ratio of 457 ppm. The number of single yarn breakages during one hour of spinning was 0.

[0090] Example 2 PPE fiber was obtained in the same manner as in Example 1, except that the total throughput rate was changed to 10.1 g / min and the spinning speed to 421 m / min. The URI value of the obtained fiber was 12.2%, the molecular configuration parameter α was 0.622, the weight retention at 350°C was 99.43%, and the low-molecular-weight polyphenylene ether component ratio was 432 ppm. The number of single yarn breakages after 1 hour of spinning was 0.

[0091] Example 3 PPE fiber was obtained in the same manner as in Example 1, except that the total throughput rate was changed to 20.0 g / min and the spinning speed to 833 m / min. The URI value of the obtained fiber was 11.9%, the molecular conformation parameter α was 0.654, the weight retention at 350°C was 99.35%, and the low-molecular-weight polyphenylene ether component ratio was 495 ppm. The number of single yarn breakages after 1 hour of spinning was 0.

[0092] Example 4 PPE fiber was obtained in the same manner as in Example 1, except that the vent was evacuated, the nozzle surface temperature was set to 344.5°C, the total discharge rate was 13.2 g / min, and the spinning speed was 550 m / min. The URI value of the obtained fiber was 8.4%, the molecular configuration parameter α was 0.598, the weight retention at 350°C was 99.62%, and the low-molecular-weight polyphenylene ether component ratio was 249 ppm. The number of single yarn breakages after 1 hour of spinning was 0.

[0093] Example 5 PPE fiber was obtained in the same manner as in Example 1, except that the vent was evacuated, the nozzle surface temperature was set to 344.5°C, the total discharge rate was 10.1 g / min, and the spinning speed was 420 m / min. The URI value of the obtained fiber was 8.3%, the molecular configuration parameter α was 0.600, the weight retention at 350°C was 99.56%, and the low-molecular-weight polyphenylene ether component ratio was 241 ppm. The number of single yarn breakages after 1 hour of spinning was 0.

[0094] Example 6 PPE fiber was obtained in the same manner as in Example 1, except that the vent was evacuated, the nozzle surface temperature was set to 344.5°C, the total discharge rate was 19.7 g / min, and the spinning speed was 821 m / min. The URI value of the obtained fiber was 9.7%, the molecular configuration parameter α was 0.606, the weight retention at 350°C was 99.53%, and the low-molecular-weight polyphenylene ether component ratio was 256 ppm. The number of single yarn breakages after 1 hour of spinning was 0.

[0095] Example 7 PPE fiber was obtained in the same manner as in Example 1, except that the temperature of cylinders 2 to 4 and the cylinder head was changed to 330°C when forming the PPE fiber. The URI value of the obtained fiber was 9.2%, the molecular configuration parameter α was 0.562, the weight retention at 350°C was 99.38%, and the low-molecular-weight polyphenylene ether component ratio was 469 ppm. The number of single yarn breakages after 1 hour of spinning was 0.

[0096] Example 8 PPE fiber was obtained in the same manner as in Example 1, except that the temperature of cylinders 2 to 4 and the cylinder head was 330°C, the nozzle surface temperature was 345°C, the total discharge rate was 33 g / min, and the spinning speed was 1,375 m / min. The URI value of the obtained fiber was 6.6%, the molecular configuration parameter α was 0.538, the weight retention at 350°C was 99.32%, and the low-molecular-weight polyphenylene ether component ratio was 473 ppm. The number of single yarn breakages after 1 hour of spinning was 0.

[0097] Comparative Example 1 PPE fiber was obtained in the same manner as in Example 1, except that the vent was removed, the nozzle surface temperature was set to 345°C, the total discharge rate was 13 g / min, and the spinning speed was changed to 542 m / min. The URI value of the obtained fiber was 34.5%, the molecular configuration parameter α was 0.700, the weight retention at 350°C was 99.20%, and the low-molecular-weight polyphenylene ether component ratio was 601 ppm. The number of single yarn breakages during 1 hour of spinning was 2.

[0098] Comparative Example 2 PPE fiber was obtained in the same manner as in Example 1, except that the vent was removed, the nozzle surface temperature was set to 344.5°C, the total discharge rate was 9.9 g / min, and the spinning speed was changed to 417 m / min. The URI value of the obtained fiber was 33.1%, the molecular configuration parameter α was 0.707, the weight retention at 350°C was 99.20%, and the low-molecular-weight polyphenylene ether component ratio was 624 ppm. The number of single yarn breakages during 1 hour of spinning was 3.

[0099] Comparative Example 3 The weight retention and molecular conformation parameter α of the raw material were measured. The molecular conformation parameter α was 0.647, the weight retention at 350°C was 99.05%, and the proportion of low-molecular-weight polyphenylene ether components was 801 ppm.

[0100]

[0101]

[0102] In Examples 1 to 8, the URI values ​​were less than 33.1%, and all of the PPE fibers had reduced fiber diameter unevenness in the fiber longitudinal direction. Furthermore, in Examples 1 to 8, no yarn breakage occurred during spinning, and the PPE fibers could be efficiently produced over a long period of time. On the other hand, in Comparative Examples 1 and 2, the URI values ​​were 33.1% or more, and all of the PPE fibers had fiber diameter unevenness in the fiber longitudinal direction. Furthermore, in Comparative Examples 1 and 2, yarn breakage occurred during spinning.

[0103] REFERENCE SIGNS LIST 1 Hopper 2 Extruder 3 Gear pump 4 Filter medium 5 Spinning nozzle 6 Filter 7 Heat-retaining space 8 Introduction of inert gas 9 Heating torch 10 Degassing vent

Claims

1. A polyphenylene ether fiber containing a polyphenylene ether component, characterized in that the Worcester (URI) value is less than 33.1%.

2. The polyphenylene ether fiber according to claim 1, wherein the molecular shape parameter α of the polyphenylene ether component in the Mark-Houwink-Sakurada equation is less than 0.

7.

3. Polyphenylene ether fiber according to claim 1, characterized in that the weight retention rate when heated from 100°C to 350°C is 99.20% or more.

4. The polyphenylene ether fiber according to claim 1, wherein the polyphenylene ether component has a rearrangement structure in which a bond at the ortho position is connected to a repeating unit that is connected via a bond at the para position.

5. The repeating units connected consecutively via the para-position bond 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 a repeating unit 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’ is the R ３ The polyphenylene ether fiber according to claim 4, characterized in that it has a structure represented by the following formula:

6. Polyphenylene ether fiber according to claim 4, characterized in that the amount of rearrangements in the polyphenylene ether component having the rearrangement structure is 0.05 mol % or more based on the total polyphenylene ether structural units in the polyphenylene ether component.

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

8. The polyphenylene ether fiber according to claim 1, wherein the single filament fineness of the polyphenylene ether fiber is 1.0 dtex or more and 100 dtex or less.

9. Activated carbon fiber characterized in that the polyphenylene ether fiber according to any one of claims 1 to 8 is used as raw fiber.

10. A method for producing polyphenylene ether fibers, comprising: a step of melt-extruding a raw material polyphenylene ether using an extruder equipped with a cylinder, a screw, and a degassing vent while degassing it through the degassing vent; and a step of discharging the molten polyphenylene ether from a spinning nozzle and spinning it.

11. The method for producing polyphenylene ether fiber according to claim 10, wherein the raw material polyphenylene ether contains polyphenylene ether having a glass transition temperature of 170°C or higher.

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