Polyarylene sulfide fiber

Abstract

This makes it possible to obtain polyarylene sulfide fibers that have excellent hydrophilicity while maintaining excellent heat resistance and chemical resistance. [Solution] A fiber characterized in that it is made from polyphenylene sulfide and at least one thermoplastic resin selected from polyphenylene ether resin, polycarbonate resin, polyethersulfone resin, polyphenylene sulfone resin, polyetherimide resin, and polysulfone resin, and at least a portion of the thermoplastic resin is exposed on the surface.

Description

Technical Field

[0001] The present invention relates to polyarylene sulfide fibers.

Background Art

[0002] Polyphenylene sulfide (hereinafter sometimes abbreviated as PPS), which is one type of polyarylene sulfide, has high heat resistance, chemical resistance, electrical insulation, and flame retardancy, and in addition, has excellent mechanical properties and molding processability. Therefore, it is widely used as a metal substitute material and a material that can withstand extreme environments. Fibers made of polyphenylene sulfide utilize the above characteristics and are used in applications such as bag filters, papermaking canvases, electrical insulation papers, battery separators, and various diaphragms. In particular, by combining the heat resistance and chemical resistance characteristics of polyphenylene sulfide against high-concentration alkaline solutions, etc., with the self-supporting, ion-permeability, gas-barrier characteristics, etc. of textile materials, research on diaphragms made of polyphenylene sulfide fibers for alkaline water electrolysis diaphragms has been actively carried out.

[0003] In hydrogen production devices, improvement in operating efficiency for the purpose of cost reduction is required. Regarding this problem, it is known that improving the ion permeability of the diaphragm in the device is effective for improving the operating efficiency of the entire device and reducing electrical resistance. Therefore, improvement in ion permeability is also required for diaphragms made of polyphenylene sulfide fibers. However, although polyphenylene sulfide is excellent in heat resistance and chemical resistance, it exhibits hydrophobicity, so it is necessary to impart hydrophilicity for further improvement in ion permeability.

[0004] Regarding this problem, for example, polyphenylene sulfide fibers that have been hydrophilically processed by plasma and / or sulfonation have been proposed (Patent Document 1). Patent Document 1 describes that gas barrier properties are enhanced by hydrophilically processing by plasma and / or sulfonation.

[0005] On the other hand, in order to further improve the properties of polyphenylene sulfide fibers, particularly their heat resistance and chemical resistance, various forms of polyphenylene sulfide fibers have been proposed. For example, a polymer alloy fiber in which polyethylene terephthalate is blended with polyphenylene sulfide has been proposed (Patent Document 2). Patent Document 2 describes that a polymer alloy fiber is obtained in which the island component of polyphenylene sulfide is dispersed with high uniformity within the sea component, and an extremely fine polyphenylene sulfide fiber can be obtained.

[0006] Furthermore, a type of composite fiber has been proposed in which the core component is made of polyester and the sheath component is composed of a blended polymer of polyester and polyphenylene sulfide (Patent Document 3). Patent Document 3 describes that by controlling the proportion of the blended polymer, a core-sheath type composite fiber with appropriate dispersion diameter and fiber properties can be obtained.

[0007] Furthermore, fibers made from a blend polymer of polyarylene sulfide (particularly polyphenylene sulfide) and polyalkylene terephthalate have been proposed (Patent Document 4). Patent Document 4 describes that by controlling the blend ratio with polyalkylene terephthalate, polyarylene sulfide fibers with excellent dimensional stability, chemical resistance, and heat resistance can be obtained. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Special Publication No. 2018-534441 [Patent Document 2] Japanese Patent Publication No. 2008-63716 [Patent Document 3] Japanese Patent Publication No. 2015-140487 [Patent Document 4] Japanese Patent Publication No. 2011-106060 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, the technology disclosed in Patent Document 1 has the problem that hydrophilicity cannot be maintained in high-temperature and strongly alkaline environments when the hydrogen production apparatus is operated for a long period of time, resulting in reduced operating efficiency.

[0010] Furthermore, although the technology disclosed in Patent Document 2 yields fibers with high uniformity of dispersion diameter, it ultimately involves the elution of marine components, and therefore does not improve the hydrophilicity of the resulting polyphenylene sulfide.

[0011] Furthermore, while the technology disclosed in Patent Document 3 obtains fibers with excellent strength and elongation by arranging polyphenylene sulfide on the fiber surface, it has the problem of reduced chemical resistance and heat resistance due to the high polyester content as the core component is polyester.

[0012] Furthermore, in Patent Document 4, a fiber with excellent chemical resistance and heat resistance has been obtained by blending a small amount of polyalkylene terephthalate with polyarylene sulfide, but there was a problem that the actual chemical resistance and heat resistance were less than that of the main component, polyarylene sulfide.

[0013] The object of the present invention is to improve upon the problems of the prior art and to obtain a polyarylene sulfide fiber that is hydrophilic while maintaining the excellent heat resistance and chemical resistance of polyphenylene sulfide. [Means for solving the problem]

[0014] As a result of diligent research by the inventors, it was found that in order to achieve both hydrophilicity, heat resistance, and alkali resistance required for the diaphragm of a hydrogen production device, it is effective to use a resin that has excellent compatibility with polyphenylene sulfide and higher hydrophilicity than polyphenylene sulfide, along with polyphenylene sulfide itself (hereinafter, the resin that is blended with polyphenylene sulfide or constitutes the fiber, and has higher hydrophilicity than polyphenylene sulfide, as well as heat resistance and chemical resistance, may be referred to as a hydrophilic polymer). Simply blending them does not yield a good hydrophilic effect because most of the hydrophilic polymer is contained as a dispersed phase inside the fiber. Therefore, the inventors have invented a hydrophilic fiber by controlling the blending ratio of the hydrophilic polymer, the melt viscosity ratio with polyphenylene sulfide, and the fiber cross-sectional structure, thereby exposing the hydrophilic polymer on the fiber surface. Furthermore, the present invention was also completed by covering the polyphenylene sulfide with a hydrophilic polymer, that is, by creating a core-sheath type fiber in which polyphenylene sulfide is the core component and the hydrophilic polymer is the sheath component.

[0015] The present invention aims to solve the above problems and employs the following means. (1) A fiber characterized in that it is made from polyphenylene sulfide and at least one thermoplastic resin selected from polyphenylene ether resin, polycarbonate resin, polyethersulfone resin, polyphenylene sulfone resin, polyetherimide resin, and polysulfone resin, and at least a portion of the thermoplastic resin is exposed on the surface. (2) A fiber as described in (1) above, having any of the characteristics of (A) to (C).

[0016] (A) Core-sheath composite fiber in which the core component is polyphenylene sulfide and the sheath component is polyphenylene sulfide and at least one thermoplastic resin selected from polyphenylene ether resin, polycarbonate resin, polyethersulfone resin, polyphenylene sulfone resin, polyetherimide resin, and polysulfone resin. (B) A core-sheath composite fiber in which the core component is polyphenylene sulfide and the sheath component is a blend polymer of polyphenylene sulfide and at least one thermoplastic resin selected from polyphenylene ether resin, polycarbonate resin, polyethersulfone resin, polyphenylene sulfone resin, polyetherimide resin, and polysulfone resin (C) A single-component fiber of a blend polymer of polyphenylene sulfide and at least one thermoplastic resin selected from polyphenylene ether resin, polycarbonate resin, polyethersulfone resin, polyphenylene sulfone resin, polyetherimide resin, and polysulfone resin (3) The fiber according to (1) or (2) above, characterized in that the value of the molar ratio O / S determined by measurement with SEM-EDX is 0.1 or more. (4) The fiber according to any one of (1) to (3) above, characterized in that the average fiber diameter is 0.5 μm or more and 15 μm or less. (5) A woven fabric or non-woven fabric containing the polyarylene sulfide fiber according to any one of (1) to (4) above. (6) A diaphragm for alkaline water electrolysis made of the woven fabric or non-woven fabric according to (5) above. (7) An electrolytic cell for alkaline water electrolysis provided with the diaphragm for alkaline water electrolysis according to (6) above.

Advantages of the Invention

[0017] According to the present invention, polyarylene sulfide fibers having excellent hydrophilicity can be obtained while maintaining excellent heat resistance and chemical resistance.

Embodiments for Carrying Out the Invention

[0018] The fiber of the present invention is composed of polyphenylene sulfide and at least one thermoplastic resin selected from polyphenylene ether resin, polycarbonate resin, polyethersulfone resin, polyphenylene sulfone resin, polyetherimide resin, and polysulfone resin. The blend ratio of the thermoplastic resin, the melt viscosity ratio with polyphenylene sulfide, the fiber The fiber is characterized in that at least a part of the thermoplastic resin is exposed on the surface by controlling the cross-sectional structure.

[0019] The present invention will be described in detail below. However, the present invention is not limited to the scope described below as long as it does not exceed the gist thereof.

[0020] <Polyarylene sulfide fiber> The polyarylene sulfide referred to in the present invention is a general term including polyphenylene sulfide and a hydrophilic polymer, and a fiber containing both of them is referred to as a polyarylene sulfide fiber.

[0021] The polyphenylene sulfide in the present invention is a polymer composed of a diphenylene sulfide unit composed of a p-phenylene sulfide unit and / or an m-phenylene sulfide unit as a main repeating unit.

[0022] In the polyphenylene sulfide in the present invention, the p-phenylene sulfide unit is preferably 60 mol% or more, more preferably 70 mol% or more, and still more preferably 80 mol% or more. By setting it within the above range, a fiber excellent in heat resistance, heat and humidity resistance, chemical resistance, and dimensional stability can be obtained.

[0023] The polyphenylene sulfide in the present invention may contain copolymerized units other than the above diphenylene sulfide units as long as the effects of the present invention are not impaired. Examples of the copolymerized units other than the diphenylene sulfide units include aromatic sulfides such as triphenylene sulfide and biphenylene sulfide, and also include alkyl-substituted products or halogen-substituted products thereof.

[0024] The polyarylene sulfide fiber of the present invention has a portion composed of a hydrophilic thermoplastic resin (hydrophilic polymer) in addition to polyphenylene sulfide. The thermoplastic resin (hydrophilic polymer) is at least one selected from polyphenylene ether, polycarbonate polyethersulfone, polyphenylene sulfone, polyetherimide, and polysulfone. These hydrophilic polymers can be used individually or in combination. Known polycarbonate, polyphenylene ether, polyethersulfone, polyphenylene sulfone, polyetherimide, and polysulfone can be used. From the viewpoint of compatibility with polyphenylene sulfide, polyphenylene ether, polyethersulfone, and polyphenylene sulfone, which have molecular structures similar to polyphenylene sulfide, are more preferred as the hydrophilic polymer.

[0025] The average fiber diameter of the polyarylene sulfide fibers of the present invention is preferably 0.5 μm or more and 15.0 μm or less. An average fiber diameter of 15.0 μm or less improves density when manufacturing woven fabrics and nonwovens, thereby improving the airtightness and ion permeability, which are physical properties of a diaphragm. The average fiber diameter is preferably 13.0 μm or less, and more preferably 10.0 μm or less.

[0026] Having an average fiber diameter of 0.5 μm or more reduces the likelihood of yarn breakage during spinning and drawing, thus ensuring productivity and process passability. Preferably, the average fiber diameter is 0.6 μm or more, and more preferably 0.7 μm or more.

[0027] The average fiber diameter (μm) of the fibers, as referred to here, can be determined by the procedure described below. Step 1: Take an image of the cross-section of the fiber using a scanning electron microscope at a magnification that allows a single fiber to be observed. Step 2: Using the captured images, use image analysis software to determine the area (μm²) formed by the cross-sectional contour of a single fiber. 2 ) is measured, and the diameter of a perfect circle with the same area is calculated. Step 3: This is measured for 100 randomly selected fibers, the number average is calculated to determine the average fiber diameter (μm), and the result is rounded to two decimal places. While the average fiber diameter of the fibers can be within the above range by adjusting the spinning discharge rate and draw ratio, other methods may be used as long as they do not hinder the objective of the present invention.

[0028] The present invention is composed of polyphenylene sulfide and a hydrophilic polymer, with at least a portion of the hydrophilic polymer exposed on the surface. A first aspect of the present invention is a fiber composed of a blend polymer of polyphenylene sulfide and a hydrophilic polymer. A second aspect of the present invention is a composite fiber composed of polyphenylene sulfide and a hydrophilic polymer. In the second aspect, for example, a core-sheath type composite fiber is provided, in which the sheath component is composed of a blend polymer of polyphenylene sulfide and a hydrophilic polymer, and in which the sheath component is composed of only a hydrophilic polymer.

[0029] In the present invention, when blending polyphenylene sulfide and hydrophilic polymer, the polyphenylene sulfide and hydrophilic polymer are subjected to 330°C for 100 seconds. -1 The melt viscosity ratio (melt viscosity of the hydrophilic polymer / melt viscosity of polyphenylene sulfide) is preferably 0.1 or more and 20.0 or less. By setting the melt viscosity ratio to preferably 0.3 or more, and more preferably 0.5 or more, the compatibility between polyphenylene sulfide and the hydrophilic polymer is maintained, and the viscosity of the hydrophilic polymer is not too low relative to that of polyphenylene sulfide, thus maintaining the strength of the fibers. By setting the melt viscosity ratio to preferably 10.0 or less, and more preferably 5.0 or less, yarn breakage is suppressed and the mechanical properties of the fibers are improved.

[0030] The cross-sectional shape of the polyarylene sulfide fiber of the present invention is not limited in any way, and can be any irregular cross-sectional shape, such as a round cross-section, a multi-lobed cross-section such as a Y-shaped cross-section or a triangular cross-section, a flat cross-section, an S-shaped cross-section, a cross-shaped cross-section, or a hollow cross-section.

[0031] The polyarylene sulfide fiber of the present invention may be a single-component fiber consisting only of a blend polymer (a) composed of the aforementioned polyphenylene sulfide and one or more hydrophilic polymers (first embodiment). The component ratio of polyphenylene sulfide in the blend polymer (a) is preferably 20% to 80%. More preferably 30% to less than 70%, and even more preferably 40% to less than 60%, the hydrophilic polymer is more easily exposed on the fiber surface, the spinnability is stable, and the balance of strength can be maintained.

[0032] Furthermore, the polyarylene sulfide fiber of the present invention may also be a composite fiber (second embodiment), and it is preferable that it has a core-sheath structure in which the core component is polyphenylene sulfide and the sheath component is only a blended polymer (a) or a hydrophilic polymer (it is a core-sheath type composite fiber). The melt viscosity ratio of the polyphenylene sulfide in the core component and the polyphenylene sulfide contained in the blended polymer (a) of the sheath component (melt viscosity of the polyphenylene sulfide in the core component / melt viscosity of the polyphenylene sulfide contained in the blended polymer (a) of the sheath component) is preferably 1.0 or higher. More preferably 1.3 or higher, and even more preferably 1.5 or higher, the sheath component, which is prone to shear stress during spinning, becomes more fluid compared to the core component, thus further improving spinnability. The sheath component may be composed of a blended polymer (a) or only a hydrophilic polymer. When the sheath component is a blended polymer (a), the component ratio of polyphenylene sulfide in the blended polymer (a) is preferably 80% or less. More preferably, by setting the content to 20% or more and less than 70%, and even more preferably 40% or more and less than 60%, the hydrophilic polymer is more easily exposed on the fiber surface, spinnability is stabilized, and sheath splitting is less likely, thus maintaining a balance between hydrophilicity and mechanical properties. The core-sheath composite ratio (weight ratio) is preferably 60 / 40 (core / sheath) or higher. Preferably, the core component ratio is 70 / 30 (core / sheath) or higher, and even more preferably 80 / 20 (core / sheath) or higher, which can improve the strength, heat resistance, and chemical resistance of the fiber. The composite form is not particularly limited as long as it does not impair the effects of the present invention, and any fiber structure other than a core-sheath structure, such as a sea-island structure, a side-by-side structure, or an eccentric core-sheath structure, can be used.

[0033] The blend polymer (a) constituting the polyarylene sulfide fiber of the present invention has a phase-separated structure consisting of polyphenylene sulfide and a hydrophilic polymer. The phase-separated structure may be a so-called sea-sea structure in which polyphenylene sulfide and hydrophilic polymer exist in layers interwoven with each other, or it may be a so-called sea-island structure having a continuous layer and a dispersed layer. In the case of a sea-island structure, the sea component may be polyphenylene sulfide and the island component may be a hydrophilic polymer, or the sea component may be a hydrophilic polymer and the island component may be polyphenylene sulfide. A sea-sea structure is preferable in order to increase the surface exposure ratio of the hydrophilic polymer.

[0034] In both the first and second embodiments of the present invention, the polyarylene sulfide fiber requires that at least a portion of the hydrophilic polymer be exposed on the surface. Preferably, the surface exposure ratio of the hydrophilic polymer is 0.05 or higher. If it is less than 0.05, the surface exposure ratio of the hydrophilic polymer is small, and the hydrophilicity of the fiber does not change significantly. Preferably, the surface exposure ratio of the hydrophilic polymer is 0.20 or higher, and more preferably 0.40 or higher.

[0035] The surface exposure ratio of the hydrophilic polymer, as used here, is the ratio of the circumference of the fiber's cross-sectional contour composed of the hydrophilic polymer to the total circumference of the fiber's cross-sectional contour. The cross-section of the fiber is observed using a transmission electron microscope (TEM), the total circumference (μm) formed by the cross-sectional contour is measured, and then the circumference (μm) formed by the hydrophilic polymer on the cross-sectional contour is measured, and the ratio is calculated. This is measured at 10 locations for 10 arbitrarily selected fibers, and the average of the calculated ratios is taken as the surface exposure ratio of the hydrophilic polymer.

[0036] The polyarylene sulfide fiber of the present invention has oxygen-containing groups, and the molar ratio O / S value, as measured by SEM-EDX, is 0.1 or higher. By having a portion of the fiber contain hydrophilic oxygen-containing groups and keeping the molar ratio O / S value within the above range, the hydrophilicity of the fiber can be improved. In the polyarylene sulfide fiber of the present invention, the molar ratio O / S is preferably 0.3 or higher, and more preferably 0.5 or higher, resulting in a polyarylene sulfide fiber with even greater hydrophilicity.

[0037] From a practical standpoint, the polyarylene sulfide fibers of the present invention preferably have a tensile strength of 2.0 cN / dtex or higher. More preferably, the tensile strength is 2.3 cN / dtex or higher, even more preferably 2.5 cN / dtex or higher, and 2.8 cN / dtex or higher, which improves the mechanical properties of the resulting woven and nonwoven fabrics. Furthermore, it becomes less likely for threads to break or snap during the manufacturing process. In addition, the woven and nonwoven fabrics become more tear-resistant even when tensile stress is applied during subsequent processes or use. Furthermore, there is no particular upper limit to the strength, but the upper limit that can be industrially achieved is about 7.0 cN / dtex.

[0038] In this invention, the tensile strength of the polyarylene sulfide fiber refers to the value measured by the method described in the Examples section.

[0039] The polyarylene sulfide fibers of the present invention preferably have a strength retention rate of 80% or more after heat treatment at 180°C for 24 hours. More preferably, a strength retention rate of 85% or more, and even more preferably 90% or more, is preferable as it provides good thermal dimensional stability for woven and nonwoven fabrics. The heat resistance of the polyarylene sulfide fibers in the present invention refers to the value measured by the method described in the Examples section. This range can be achieved by blending polyphenylene sulfide with a highly heat-resistant resin, but other methods may be used as long as they do not hinder the objective of the present invention.

[0040] The polyarylene sulfide fibers of the present invention preferably have a strength retention rate of 90% or more when immersed in a 30% by mass potassium hydroxide aqueous solution at 90°C for 24 hours. More preferably, it is 93% or more, and even more preferably 95% or more. By maintaining the above range, the strength can be maintained even in high-temperature alkaline environments, allowing for long-term use in hydrogen production equipment. Originally, polyphenylene sulfide fibers are highly resistant to alkalis. However, when a resin with low alkali resistance is mixed with polyphenylene sulfide fibers, components other than polyphenylene sulfide decompose due to the alkali, and the strength of the fiber tends to decrease. However, the polyarylene sulfide fibers of the present invention have succeeded in maintaining alkali resistance by mixing them with a hydrophilic polymer with high chemical resistance. Note that the alkali resistance of the polyarylene sulfide fibers in the present invention refers to the value measured by the method described in the Examples section.

[0041] The fabric of the present invention is a fabric containing the polyarylene sulfide fibers of the present invention. The weave structure of the fabric may be plain weave, twill weave, satin weave, or a combination of these, or a modified pile weave or patterned weave, but plain weave is preferred because it has the most weave points and allows for high density.

[0042] The nonwoven fabric of the present invention is a nonwoven fabric containing the polyarylene sulfide fibers of the present invention. In the nonwoven fabric of the present invention, the type of nonwoven fabric is not particularly limited, and examples include spunbond nonwoven fabric, meltblown nonwoven fabric, spunlace nonwoven fabric, needle-punched nonwoven fabric, wet-laid nonwoven fabric, etc., but wet-laid nonwoven fabric is preferred because it can be obtained as a nonwoven fabric with high airtightness and high uniformity.

[0043] <Method for producing polyarylene sulfide fibers> The following describes a method for producing the polyarylene sulfide fibers of the present invention, but it is not limited to this method.

[0044] A known method can be used to produce the polyphenylene sulfide used in the present invention. For example, one method involves reacting an alkali metal sulfide such as sodium sulfide with p-dichlorobenzene and m-dichlorobenzene in an organic amide solvent such as N-methyl-2-pyrrolidone to obtain polyphenylene sulfide.

[0045] The method for producing the polyarylene sulfide fibers of the present invention is not particularly limited, but examples include blending in a spinning machine or melt-kneading polyphenylene sulfide and a hydrophilic polymer beforehand and then forming the fibers. In particular, blending polyphenylene sulfide and a hydrophilic polymer beforehand to form a blended polymer (a) and then forming the fibers is more preferable because it improves the spinnability during fiber production according to the present invention by improving the dispersibility of polyphenylene sulfide and the hydrophilic polymer.

[0046] The shape of the polyphenylene sulfide used in the production of the polyarylene sulfide fibers of the present invention is not particularly limited. For example, if the resin is in the form of granules or powder according to known manufacturing methods, it may be used as is. Alternatively, it may be used after being processed into flakes or pellets.

[0047] The shape of the hydrophilic polymer used in this invention is not particularly limited and can be, for example, pellets, flakes, granules, or powder. For melt mixing, known heating and melting mixing apparatus can be used. As heating and melting mixing apparatus, a single-screw extruder, a twin-screw extruder, a multi-screw extruder equipped with three or more screws, a multi-screw extruder with a combination thereof, a kneader-ruder, etc. Among these, a twin-screw extruder is preferred because it improves the dispersibility of polyphenylene sulfide and the hydrophilic polymer, thereby improving spinnability.

[0048] In the melt-mixing method, the method of supplying polyphenylene sulfide and hydrophilic polymer to the mixer during mixing is not particularly limited. Examples include a method of pre-blending polyphenylene sulfide and hydrophilic polymer and supplying them to the mixer, a method of supplying polyphenylene sulfide and hydrophilic polymer to the mixer while weighing each, and a method of supplying the hydrophilic polymer to the mixer that has already been supplied with polyphenylene sulfide via a side feed. The melt-mixing temperature is preferably 280 to 350°C. Here, temperature refers to the temperature of the resin in the mixing section or at the tip of the mixer. This can usually be measured by attaching a thermometer to the tip of the mixer. It is preferable to keep the melt-mixing temperature within this range because it results in good spinning stability and good quality of the resulting fibers, including strength and color.

[0049] The kneading time is not particularly limited, but it is preferably between 0.5 and 30 minutes. This range of kneading time is preferable because it suppresses the thermal decomposition of polyphenylene sulfide or hydrophilic polymer, resulting in better spinning stability and improved fiber strength, color, and other quality characteristics.

[0050] The polyarylene sulfide fibers of the present invention are preferably obtained by melt-spinning the above-mentioned blend polymer (a) and then melt-spinning it.

[0051] The blended polymer (a) used in the present invention is preferably dried before melt spinning to prevent moisture contamination and remove oligomers, thereby improving its spinnability. Typically, vacuum drying at 100-200°C for 1-24 hours is used as the drying condition.

[0052] From the viewpoint of productivity, the polyarylene sulfide fiber of the present invention is preferably multifilamentous, and the fineness of the multifilament is preferably 20 dtex or more.

[0053] In melt spinning, melt spinning methods using extruders such as pressure melter type, uniscrew, or twin-screw extruder type can be applied. The extruded blend polymer passes through piping, is weighed by a metering device such as a gear pump, passes through a filter to remove foreign matter, and is then led to the spinneret. At this time, the temperature from the resin piping to the spinneret (spinning temperature) is preferably 280°C or higher to increase fluidity, and preferably 380°C or lower to suppress thermal decomposition of the resin.

[0054] In the spinneret used for extrusion, it is preferable that the diameter D of the spinneret hole be 0.1 mm or more and 0.6 mm or less, and that L / D, defined as the quotient obtained by dividing the land length L of the spinneret hole (length of the straight tube section with the same diameter as the spinneret hole) by the hole diameter, be 1 or more and 10 or less.

[0055] The blended polymer fibers discharged from the nozzle holes are cooled and solidified by blowing cooling air (air) onto them. The temperature of the cooling air can be determined by balancing it with the cooling air velocity from the viewpoint of cooling efficiency, but it is preferable that it be 30°C or lower. By preferably keeping the temperature of the cooling air at 30°C or lower, the solidification behavior due to cooling is stabilized, resulting in polyarylene sulfide fibers with high fiber diameter uniformity.

[0056] Furthermore, it is preferable to direct the cooling air in a direction almost perpendicular to the undrawn fibers discharged from the die. In this case, the speed of the cooling air is preferably 10 m / min or more from the viewpoint of cooling efficiency and uniformity of fineness, and preferably 100 m / min or less from the viewpoint of yarn production stability.

[0057] The cooled and solidified undrawn fibers are taken up by a roller (godette roller) that rotates at a constant speed. The take-up speed is preferably 300 m / min or more for linear uniformity and improved productivity, and preferably 2000 m / min or less to prevent yarn breakage.

[0058] The undrawn fibers obtained in this way are subjected to a drawing process immediately after being wound up or taken up. Drawing is performed by running the fibers through a heated first roller or a heating device installed between the first and second rollers, for example, in a heating bath or on a hot plate. The drawing conditions are determined by the mechanical properties of the obtained undrawn fibers, the drawing temperature is determined by the temperature of the heated first roller or the heating device installed between the first and second rollers, and the drawing ratio is determined by the ratio of the peripheral speeds of the first and second rollers.

[0059] In the stretching process, the temperature of the heated first roller or heating device is preferably between 80°C and 140°C. Setting the temperature above 80°C fixes the stretching point, enabling stable stretching, while setting it below 140°C suppresses yarn breakage and improves process passability.

[0060] Furthermore, after passing through the second roller, the drawn fibers must be heated by a heated third roller or a heating device installed between the second and third rollers to perform a heat set. The heat set temperature in the above heat set is preferably between 110°C and 250°C. By setting the heat set temperature preferably to 140°C or higher, more preferably to 160°C or higher, thermal crystallization is promoted, resulting in polyarylene sulfide fibers with excellent mechanical properties. Also, by setting the heat set temperature preferably to 220°C or lower, more preferably to 210°C or lower, the fusion of the fibers to the rollers is suppressed. In this way, drawn fibers are obtained.

[0061] <Manufacturing methods for textiles> The following describes a method for manufacturing the fabric of the present invention, but it is not limited to this method. The polyarylene sulfide fibers of the present invention are used as warp and / or weft threads, and after warping, heddling, and reeding, weaving is carried out using a gripper loom or a heavy rapier loom.

[0062] The fabric produced is scouring in a water bath at a temperature of 90-95°C and a speed of 20-40 m / min. A scouring temperature of 90°C or higher makes it easier to remove dirt from the fabric, while a temperature below 95°C reduces energy consumption. A scouring speed of 20 m / min or higher increases production efficiency, while a speed of 40 m / min or lower allows the scouring solution to come into sufficient contact with the filter cloth, completely washing away dirt. During scouring, it is preferable to add a scouring agent such as soda ash to remove hydrophobic impurities. After rinsing, a heat setting speed of 5 m / min or higher suppresses shrinkage, wrinkle formation, and deterioration of the fabric's texture. A speed of 15 m / min or lower increases heat setting efficiency. The fabric is thus obtained.

[0063] <Method for manufacturing wet-laid nonwoven fabrics> The following describes a method for producing the nonwoven fabric of the present invention, but it is not limited to this method. Cut fibers are obtained by cutting the polyarylene sulfide fibers of the present invention to a predetermined length with a cutter.

[0064] The obtained cut fibers are dispersed in an aqueous medium. Here, the aqueous medium refers to a liquid whose main component is water. These dispersions are mixed in the desired proportions to form a papermaking dispersion. Binder fibers or other fibers may be added to the papermaking fiber dispersion as an adhesive between the fibers.

[0065] The fiber dispersion for papermaking may contain surfactants as dispersants, water-soluble polymers as thickeners, and defoaming agents to suppress foam formation.

[0066] The papermaking dispersion prepared as described above is used to make paper using a papermaking machine such as a round-mesh type, long-mesh type, or inclined-mesh type, or a hand-made papermaking machine. This is then dried with a Yankee dryer or rotary dryer to obtain a dry web. After that, it is subjected to heating and pressurizing treatment to obtain a wet nonwoven fabric.

[0067] The temperature conditions for the heating and pressurizing treatment are preferably above the glass transition temperature of the binder fibers and below the melting point of the polyarylene sulfide fibers. A wet-laid nonwoven fabric is obtained in this manner.

[0068] <Diaphragm for alkaline water electrolysis> The alkaline water electrolysis diaphragm of the present invention is made of the aforementioned woven fabric or nonwoven fabric. Because such an alkaline water electrolysis diaphragm is made of the aforementioned woven fabric or nonwoven fabric, it has excellent heat resistance, chemical resistance, and hydrophilicity, and can therefore be used as a diaphragm. [Examples]

[0069] The polyarylene sulfide fibers of the present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples. Various modifications and alterations are possible without departing from the technical scope of the present invention. The characteristic values ​​in the examples were determined by the following method.

[0070] [Measurement and Evaluation Methods] (1) Average fiber diameter A scanning electron microscope, the "S-5500" manufactured by Hitachi High-Technologies Corporation, and image analysis software, "WinROOF2015" manufactured by Mitani Corporation, were used, and measurements were performed as described below. Step 1: Take an image of the cross-section of the fiber using a scanning electron microscope at a magnification that allows a single fiber to be observed. Step 2: Using the captured image, use image analysis software to determine the area Af(μm²) formed by the cross-sectional contour of a single fiber. 2 ) is measured, and the diameter of a perfect circle that has the same area as this area Af is calculated. Step 3: Measure this for 100 randomly selected fibers, calculate the number mean to determine the average fiber diameter (μm), and round it to two decimal places.

[0071] (2) Melt viscosity The following is a method for measuring melt viscosity to calculate the melt viscosity ratio of polyphenylene sulfide and hydrophilic polymer. Chip-shaped polymers were dried in a vacuum dryer to a moisture content of 200 ppm or less, and the melt viscosity was measured using a capillary graph manufactured by Toyo Seiki Seisakusho Co., Ltd., by gradually changing the strain rate. The measurement temperature was 330°C, and the time from placing the sample in the heating furnace under a nitrogen atmosphere to the start of measurement was 5 minutes, with a shear rate of 100 sec. -1 The value was evaluated as the melt viscosity of the polymer. Furthermore, the melt viscosity ratio of polyphenylene sulfide to hydrophilic polymer was obtained by dividing the melt viscosity of the hydrophilic polymer by the melt viscosity of polyphenylene sulfide and rounding the value to two decimal places.

[0072] (3) Strength, elongation The strength and elongation of the fibers were measured using Tensilon (UTM-III-100, manufactured by Orientec Co., Ltd.) according to "Chapter 8.5 Tensile Strength and Elongation" of JIS L1013:2010, with a sample length of 200 mm and a tensile speed of 200 mm / min. Five measurements were taken for each level, and the arithmetic mean was calculated as strength (cN / dtex) and elongation (%).

[0073] (4) Surface exposure ratio of hydrophilic polymers The fiber cross-sections were observed and photographed using a transmission electron microscope (JEOL JEM-1400Plus) under an acceleration voltage of 100kV. The total circumference (μm) formed by the cross-sectional contour of the dispersed phase was measured using image processing software (WINROOF2015), and the circumference (μm) formed by the hydrophilic polymer in the cross-sectional contour was also measured. The ratio of these two ratios was then calculated. This measurement was performed at 10 locations on 10 randomly selected fibers, and the average of the calculated ratios, rounded to three decimal places, was defined as the surface exposure ratio of the hydrophilic polymer.

[0074] (5) Molar ratio of oxygen atoms to 1 mole of sulfur atoms (molar ratio O / S) Using a scanning electron microscope (SEM-EDX) from Hitachi High-Tech (SU1510), the molar ratio of oxygen atoms to sulfur atoms was measured on polyarylene sulfide fibers under an acceleration voltage of 15kV. The simple number average of three measurements was calculated and rounded to the third decimal place.

[0075] (6) Heat resistance (strength retention rate) The fibers were heated in an oven temperature-controlled to 180°C for 24 hours. The strength of the fibers after the heat treatment was measured, and the strength retention rate (%) was calculated as the ratio (100 × strength after heat treatment / initial strength) to the initial strength (strength measured in item (3) above; the same applies hereafter).

[0076] (7) Alkali resistance The fibers were immersed in a 30% potassium hydroxide aqueous solution. The potassium hydroxide solution was then heated, and the tensile strength of the fibers after heat treatment at 90°C for 24 hours was measured. The strength retention rate (%) was calculated as the ratio of the heat-treated strength to the initial strength (100 × strength after heat treatment / initial strength).

[0077] [Example 1] A blended polymer was obtained by melt-kneading polyphenylene sulfide, consisting solely of p-phenylene sulfide units, with polyethersulfone at a ratio of 55% by mass relative to the total mass in a twin-screw kneader at a melting temperature of 330°C and a screw rotation speed of 300 rpm. The polyphenylene sulfide and polyethersulfone used in this process were melted at 330°C for 100 seconds. -1The melt viscosities were 81 Pa·sec and 360 Pa·sec, respectively. The resulting blended polymer was vacuum-dried at 150°C for 12 hours, and then melt-spun at a spinning temperature of 330°C. In melt spinning, polyphenylene sulfide with a melt viscosity of 127 Pa·sec and the blended polymer were melted separately, and the core-sheath ratio was calculated to be 80 / 20 (core / sheath) by weight ratio. The polymers were then melt-extruded and supplied to the spinning pack and spinneret while being weighed using a gear pump. Subsequently, the blended polymer was extruded from a round-hole spinneret with 36 holes at a single-hole extrusion rate of 0.34 g / min.

[0078] The blended polymer extruded from the die passed through a 50 mm heat-insulating area, and was then air-cooled over a distance of 1.0 m using a uniflow type cooling device at a temperature of 25°C and an airflow of 18 m / min. After that, an oil was applied, and the 36 filaments were wound together on a winder via a first and second godet roller at a speed of 1000 m / min to obtain undrawn fibers.

[0079] The undrawn fibers described above were taken up by a feed roller equipped with a nip roller, tension was applied to the undrawn fibers between the first and second rollers, and then heat-drawn by passing them six times on the first and second rollers, which were heated to 90°C and 120°C respectively. Furthermore, they were passed six times on the third roller, which was heated to 180°C, for heat setting. The total draw ratio was 3.8 times. After passing through the third roller, the fibers were taken up by an unheated roller at a peripheral speed of 400 m / min and then wound up with a winder to obtain polyarylene sulfide fibers. The results are shown in Table 1.

[0080] [Examples 2-5] As shown in Table 1, polyarylene sulfide fibers were obtained in the same manner as in Example 1, except that the ratio of polyethersulfone to the total mass of the blended polymer and the core-sheath ratio in the spinning process were changed.

[0081] [Example 6] As shown in Table 1, polyarylene sulfide fibers were obtained in the same manner as in Example 1, except that the sheath polymer was changed to polyethersulfone only.

[0082] [Example 7] As shown in Table 1, polyarylene sulfide fibers were obtained in the same manner as in Example 1, except that the polymer blended with polyphenylene sulfide was changed to polyphenylene sulfone, and the ratio of polyphenylene sulfone to the total mass of the blended polymer and the core-sheath ratio in the spinning process were changed.

[0083] [Example 8] A blended polymer was obtained by melt-kneading polyphenylene sulfide, consisting solely of p-phenylene sulfide units, with polyethersulfone at a ratio of 45% by mass relative to the total mass in a twin-screw kneader under conditions of a melting temperature of 330°C and a screw rotation speed of 300 rpm. The polyphenylene sulfide and polyethersulfone used in this process were melted at 330°C for 100 seconds. -1 The melt viscosities were 127 Pa·sec and 360 Pa·sec, respectively. The resulting blended polymer was vacuum-dried at 150°C for 12 hours, and then melt-spun at a spinning temperature of 330°C. In melt spinning, the blended polymer was melt-extruded and supplied to the spinning pack and spinneret while being weighed with a gear pump. Subsequently, the blended polymer was extruded from a round-hole spinneret with 36 holes at a single-hole discharge rate of 0.34 g / min.

[0084] The blended polymer extruded from the die passed through a 50 mm heat-insulating area, and was then air-cooled over a distance of 1.0 m using a uniflow type cooling device at a temperature of 25°C and an airflow of 18 m / min. After that, an oil was applied, and the 36 filaments were wound together on a winder via a first and second godet roller at a speed of 1000 m / min to obtain undrawn fibers.

[0085] The undrawn fibers described above were taken up by a feed roller equipped with a nip roller, tension was applied to the undrawn fibers between the first and second rollers, and then heat-drawn by passing them six times on the first and second rollers, which were heated to 90°C and 120°C respectively. Furthermore, they were passed six times on the third roller, which was heated to 180°C, for heat setting. The total draw ratio was 3.8 times. After passing through the third roller, the fibers were taken up by an unheated roller at a peripheral speed of 400 m / min and then wound up with a winder to obtain polyarylene sulfide fibers. The results are shown in Table 1.

[0086] [Examples 9 and 10] As shown in Table 1, polyarylene sulfide fibers were obtained in the same manner as in Example 8, except that the ratio of polyethersulfone to the total mass was changed.

[0087] [Table 1]

[0088] [Example 11] As shown in Table 1, polyarylene sulfide fibers were obtained in the same manner as in Example 8, except that the polymer blended with polyphenylene sulfide was changed to polyphenylene sulfone, and the ratio of polyphenylene sulfone to the total mass was changed.

[0089] [Examples 12, 13] As shown in Table 1, polyarylene sulfide fibers were obtained in the same manner as in Example 1, except that the melt viscosity ratio of polyphenylene sulfide and hydrophilic polymer in the blended polymer was changed.

[0090] [Examples 14, 15] Polyarylene sulfide fibers were obtained in the same manner as in Example 1, except that the single-hole extrusion rates in the spinning process were changed to 0.57 g / min and 0.84 g / min, respectively.

[0091] [Comparative Example 1] As shown in Table 1, polyarylene sulfide fibers were obtained in the same manner as in Example 1, except that the core-sheath ratio in the spinning process was changed.

[0092] [Comparative Example 2] As shown in Table 1, polyarylene sulfide fibers were obtained in the same manner as in Example 1, except that the polymer blended with polyphenylene sulfide was changed to polyethylene terephthalate, and the ratio of polyethylene terephthalate to the total mass of the blended polymer and the core-sheath ratio in the spinning process were changed.

[0093] [Comparative Example 3] As shown in Table 1, polyarylene sulfide fibers were obtained in the same manner as in Example 8, except that the ratio of polyethersulfone to the total mass was changed.

[0094] [Comparative Example 4] As shown in Table 1, polyarylene sulfide fibers were obtained in the same manner as in Example 8, except that the polymer blended with polyphenylene sulfide was changed to polyethylene terephthalate and the ratio of polyethylene terephthalate to the total mass was changed.

[0095] [Comparative Example 5] As shown in Table 1, spinning was carried out in the same manner as in Example 1, except that the melt viscosity ratio of polyphenylene sulfide and hydrophilic polymer in the blended polymer was changed. However, due to poor spinnability, yarn breakage occurred frequently, making it difficult to wind the polyarylene sulfide fibers.

[0096] [Table 2]

Claims

1. A polyarylene sulfide fiber characterized by being composed of polyphenylene sulfide and at least one thermoplastic resin selected from polyphenylene ether resin, polycarbonate resin, polyethersulfone resin, polyphenylene sulfone resin, polyetherimide resin, and polysulfone resin, wherein at least a portion of the thermoplastic resin is exposed on the surface.

2. A polyarylene sulfide fiber according to claim 1, having any of the following characteristics (A) to (C). (A) Core-sheath type composite fiber in which the core component is polyphenylene sulfide and the sheath component is polyphenylene sulfide and at least one thermoplastic resin selected from polyphenylene ether resin, polycarbonate resin, polyethersulfone resin, polyphenylene sulfone resin, polyetherimide resin, and polysulfone resin. (B) Core-sheath type composite fiber in which the core component is polyphenylene sulfide and the sheath component is a blend polymer of polyphenylene sulfide and at least one thermoplastic resin selected from polyphenylene ether resin, polycarbonate resin, polyethersulfone resin, polyphenylene sulfone resin, polyetherimide resin, and polysulfone resin. (C) Single-component fiber of a blend polymer of polyphenylene sulfide and at least one thermoplastic resin selected from polyphenylene ether resin, polycarbonate resin, polyethersulfone resin, polyphenylene sulfone resin, polyetherimide resin, and polysulfone resin.

3. The polyarylene sulfide fiber according to claim 1 or 2, characterized in that the molar ratio O / S value obtained by measurement with SEM-EDX is 0.1 or greater.

4. The polyarylene sulfide fiber according to claim 1 or 2, characterized in that the average fiber diameter is 0.5 μm or more and 15 μm or less.

5. A woven or nonwoven fabric comprising the polyarylene sulfide fiber according to claim 1 or 2.

6. A diaphragm for alkaline water electrolysis, comprising the woven or nonwoven fabric described in claim 5.

7. An electrolytic cell for alkaline water electrolysis, comprising the diaphragm for alkaline water electrolysis described in claim 6.

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