Activated carbon fiber, activated carbon fiber molded body, production methods for these, organic solvent adsorption / desorption processing device, organic solvent recovery system, organic solvent adsorption / desorption processing method, and organic solvent recovery method

Abstract

The purpose of the present invention is to provide highly flexible activated carbon fiber, an activated carbon fiber molded body, and production methods for these. Another purpose of the present invention is to provide an organic solvent adsorption / desorption processing device, an organic solvent recovery system, an organic solvent adsorption / desorption processing method, and an organic solvent recovery method. The present invention relates to activated carbon fiber wherein the degree R of deformation of fibers as expressed by formula 1 is 1.10-2.00, the pore volume for a pore diameter of not less than 0.7 nm but less than 1.3 nm is not less than 0.08 cm3 / g but less than 0.22 cm3 / g, and the pore volume for a pore diameter of 1.3-2.3 nm is 0.02-0.20 cm3 <sp / >.　Formula 1: degree R of deformation = circumscribed circle diameter / inscribed circle diameter (where the circumscribed circle diameter is the diameter of a circle circumscribing a fiber cross-section, and the inscribed circle diameter is the diameter of a circle inscribed in the fiber cross-section).

Description

Activated carbon fiber, activated carbon fiber molded articles, methods for producing the same, organic solvent adsorption / desorption apparatus, organic solvent recovery system, organic solvent adsorption / desorption method, and organic solvent recovery method.

[0001] The present invention relates to activated carbon fibers having a non-standard cross-section, activated carbon molded articles, methods for producing the same, organic solvent adsorption / desorption processing apparatus, organic solvent recovery system, organic solvent adsorption / desorption processing method, and organic solvent recovery method.

[0002] Because activated carbon fibers have a large specific surface area and can adsorb and desorb organic solvents and harmful substances, molded products made from activated carbon fibers are used in a wide range of fields, including industrial materials.

[0003] Various types of activated carbon fibers are known, including those that use polyacrylonitrile fibers, cellulose fibers, pitch fibers, and phenolic fibers as precursors. Patent Document 1 proposes a method for producing phenolic carbon fibers by carbonizing phenolic fibers produced by a method for producing phenolic fibers, which comprises a raw material mixing step of mixing phenolic resin and fatty acid amides, and a spinning step of spinning the raw material mixture obtained in the raw material mixing step to obtain yarn, and a method for producing phenolic activated carbon fibers by activating the phenolic carbon fibers produced by the above method.

[0004] Furthermore, pitch-based fibrous activated carbon, in which the single filaments constituting the fibrous activated carbon have an irregular cross-sectional shape, and nonwoven fabric sheets made using such activated carbon are known (see, for example, Patent Document 2). Also known are activated carbon fibers using polyphenylene ether fibers as a precursor (see, for example, Patent Document 3).

[0005] Japanese Patent Publication No. 2012-52283, Japanese Patent Publication No. 61-296124, International Publication No. 2022 / 202375

[0006] Activated carbon fibers are primarily used as filters for applications such as recovering organic solvents and removing harmful substances. Since activated carbon fiber filters are generally incorporated into equipment, high flexibility is required for both the activated carbon fibers and the activated carbon fiber molded products. In particular, extremely high flexibility is required when the activated carbon fiber filter is wound around a cylinder and used as a cylindrical activated carbon fiber nonwoven fabric element.

[0007] Furthermore, when using activated carbon fibers as filters, increasing the diameter of the activated carbon fibers is required to reduce pressure loss. However, increasing the diameter of activated carbon fibers leads to problems such as a decrease in fiber properties and a reduction in flexibility due to fusion between fibers. Currently, highly flexible activated carbon fibers or activated carbon fiber molded products are not known. In addition, the development of highly flexible activated carbon fibers is required from a productivity standpoint.

[0008] Furthermore, while Patent Document 2 describes the formation of pitch-based fibrous activated carbon with an irregular cross-sectional shape for the purpose of improving adsorption, the nonwoven fabric sheet made of this pitch-based fibrous activated carbon is used in sheet form, and no consideration has been given to its flexibility. Similarly, in Patent Document 3, no consideration has been given to flexibility. In particular, the flexibility of activated carbon fiber formation bodies using activated carbon fibers with polyphenylene ether fibers as a precursor has not been considered at all in the past.

[0009] In view of the above problems, the present invention aims to provide highly flexible activated carbon fibers, activated carbon fiber molded articles, and methods for producing the same. The present invention also aims to provide an organic solvent adsorption / desorption apparatus, an organic solvent recovery system, an organic solvent adsorption / desorption method, and an organic solvent recovery method.

[0010] As a result of diligent research, the inventors of this invention discovered that the above problems can be solved by using activated carbon fibers having a specific degree of irregularity, and thus completed the present invention.

[0011] The present invention relates to an activated carbon fiber, wherein the modified degree R of the fiber represented by the following formula 1 is 1.10 or more and 2.00 or less. Modified degree R = diameter of circumscribed circle / diameter of inscribed circle (Formula 1) (In the formula, the diameter of the circumscribed circle is the diameter of a circle circumscribed to the fiber cross-section, and the diameter of the inscribed circle is the diameter of a circle inscribed to the fiber cross-section.)

[0012] Furthermore, the present invention relates to an activated carbon fiber, wherein the modified degree R of the fiber represented by the following formula 1 is 1.10 or more and 2.00 or less, the pore volume of pores having a pore diameter of 0.7 nm or more and less than 1.3 nm is 0.08 cm ３ / g or more and less than 0.22 cm ３ / g, and the pore volume of pores having a pore diameter of 1.3 nm or more and 2.3 nm or less is 0.02 cm ３ / g or more and 0.20 cm ３ / g or less. Modified degree R = diameter of circumscribed circle / diameter of inscribed circle (Formula 1) (In the formula, the diameter of the circumscribed circle is the diameter of a circle circumscribed to the fiber cross-section, and the diameter of the inscribed circle is the diameter of a circle inscribed to the fiber cross-section.)

[0013] When T1 is the perimeter of the cross-section of the activated carbon fiber and T2 is the perimeter of a round cross-section fiber having the same fiber cross-sectional area as the activated carbon fiber, the perimeter ratio (T1 / T2) is preferably 1.05 or more and 1.40 or less.

[0014] Furthermore, the present invention relates to an activated carbon fiber molded body formed of the activated carbon fiber.

[0015] Furthermore, the present invention relates to an activated carbon fiber molded body formed of activated carbon fibers, wherein the flexibility is 5 mN or more and 200 mN or less.

[0016] The activated carbon fiber molded body is preferably an activated carbon fiber nonwoven fabric.

[0017] The nonwoven fabric has a bulk density of 100 kg / m ３ or more and 300 kg / m ３ or less, and preferably has a pressure loss coefficient of 0.80 mmAq·s / cm ２ or less when air is passed through at a linear velocity of 30 cm / sec.

[0018] Preferably, the activated carbon fiber uses polyphenylene ether fiber as a precursor.

[0019] Furthermore, the present invention relates to a method for producing said activated carbon fiber, which comprises activating carbon fiber obtained by carbonizing raw material polyphenylene ether fiber, and to a method for producing said activated carbon fiber molded body, which comprises activating a carbonized molded body obtained by carbonizing a fiber molded body formed of raw material polyphenylene ether fiber.

[0020] Preferably, the degree of profile irregularity R of the fiber represented by the following formula 1 of the raw material polyphenylene ether fiber is 1.10 or more and 2.00 or less. Degree of profile irregularity R = diameter of circumscribed circle / diameter of inscribed circle (Formula 1) (In the formula, the diameter of the circumscribed circle is the diameter of a circle circumscribed to the fiber cross section, and the diameter of the inscribed circle is the diameter of a circle inscribed to the fiber cross section.)

[0021] Furthermore, the present invention relates to an organic solvent adsorption and desorption treatment apparatus, an organic solvent recovery system, an organic solvent adsorption and desorption treatment method, and an organic solvent recovery method that use an adsorbent comprising said activated carbon fiber molded body.

[0022] When the carbon fiber is activated (activation treatment) during the formation of activated carbon fiber, gasification of the carbon fiber progresses due to the activation, resulting in an increased activation degree, and the flexibility of an activated carbon fiber molded body formed from the activated carbon fiber generally tends to increase. That is, there is a correlation between the activation degree of activated carbon fiber and flexibility.

[0023] On the other hand, in an activated carbon fiber using polyphenylene ether fiber as a precursor, the pore volume of pores with a pore diameter of 0.7 nm or more and less than 1.3 nm is 0.08 cm ３ / g or more and 0.22 cm ３ / g or less, and the pore volume of pores with a pore diameter of 1.3 nm or more and 2.3 nm or less is 0.02 cm ３ / g or more and 0.20 cm ３For activated carbon fibers with an activation degree of less than 1 / g, the flexibility of the activated carbon fiber structure formed from the activated carbon fiber tended to be low, making it difficult to incorporate into equipment. In the present invention, even with activated carbon fibers with such a low activation degree, the fiber deformation degree R is 1.10 to 2.00, and the contact area between fibers can be reduced compared to activated carbon fibers with a circular cross-sectional shape. As a result, the activated carbon fibers of the present invention have high flexibility and can be stably processed into adsorbent elements in the next process. Furthermore, the flexibility of fiber molded articles such as filters formed from the activated carbon fibers is improved, allowing them to be incorporated into equipment and used without cracks or breaks. In addition, in the manufacturing method of the activated carbon fibers, it is also advantageous that the activation time can be shortened by increasing the outer surface area of ​​the fibers. The activated carbon fibers of the present invention can be suitably used as an adsorbent with excellent adsorption performance.

[0024] Furthermore, the activated carbon fiber molded article of the present invention can be used as an adsorbent in an organic solvent adsorption / desorption treatment apparatus, an organic solvent recovery system, an organic solvent adsorption / desorption treatment method, and an organic solvent recovery method.

[0025] This is a schematic cross-sectional view showing one embodiment of a method for producing PPE fibers used in the present invention. This is a schematic cross-sectional view showing one embodiment of a cross-section of an activated carbon fiber of the present invention. This is a schematic cross-sectional view showing a cross-section of an activated carbon fiber of the present invention and a cross-section of a round cross-section fiber having the same area as the activated carbon fiber. This is a schematic cross-sectional view showing one embodiment of a spinning nozzle used in the present invention. This is a flow diagram showing one embodiment of an organic solvent recovery system of the present invention.

[0026] 1. Activated carbon fibers The degree of irregularity R of the activated carbon fibers of the present invention is 1.10 or more and 2.00 or less.

[0027] The aforementioned deformation degree R corresponds to a perfect circle when it is 1.00, and the larger the deformation degree R, the more deformed the fiber cross-section is. As shown in Figure 2, the cross-section 11 of the activated carbon fiber is photographed in two dimensions, and from the image, the diameter of the perfect circle circumscribed around the fiber cross-section (circumscribed circle 12 in Figure 2) is taken as the circumscribed circle diameter, and further, the diameter of the perfect circle inscribed inside the fiber cross-section (inscribed circle 13 in Figure 2) is taken as the inscribed circle diameter. The deformation degree R is calculated using the above formula 1, and the result is obtained by calculating to three decimal places and rounding to the third decimal place.

[0028] The degree of irregularity R of the activated carbon fiber of the present invention is 1.12 or higher, preferably 1.14 or higher, and more preferably 1.15 or higher. Furthermore, the degree of irregularity R is 2.00 or lower, preferably 1.90 or lower, more preferably 1.80 or lower, and even more preferably 1.75 or lower. If the degree of irregularity R is less than 1.10, the fibers tend to fuse together, impairing flexibility. Also, if the degree of irregularity R exceeds 2.00, the flexibility of the fiber tends to be impaired. Moreover, molded articles such as filters made from fibers with a degree of irregularity R exceeding 2.00 tend to have high pressure loss. In addition, fibers with a large degree of irregularity R may not be able to maintain their cross-sectional shape during processing.

[0029] The activated carbon fiber of the present invention is not particularly limited in its cross-sectional shape as long as it satisfies the above degree of irregularity, but may have, for example, a leaf-shaped (3 to 20 leaf) cross-section or a polygonal cross-section. A leaf-shaped cross-section is, for example, a shape in which four slits are arranged radially from the center of the circumscribed circle in the case of a 4-leaf shape, and a shape in which eight slits are arranged radially from the center of the circumscribed circle in the case of an 8-leaf shape. A shape in which a number of slits are arranged radially from the center of the circumscribed circle is also called an "a-leaf cross-section". Figure 2 shows a 5-leaf cross-section. In the present invention, a leaf-shaped cross-section of three or more leaves is preferred from the viewpoint of flexibility of the activated carbon fiber molded article, and four or more leaves are more preferred.

[0030] Because the cross-sectional shape of the activated carbon fiber of the present invention is irregular, its outer circumference is larger compared to a round cross-sectional fiber having the same fiber cross-sectional area. As shown in Figure 3, when the outer circumference of the cross-section of the activated carbon fiber (cross-sectional area S) is T1, and the outer circumference of a round cross-sectional fiber having the same fiber cross-sectional area S as the activated carbon fiber is T2, it is preferable that the outer circumference ratio (T1 / T2) is 1.05 or more and 1.40 or less. Setting the outer circumference ratio within this range is preferable from the viewpoint of the flexibility of the activated carbon fiber.

[0031] The T1 / T2 ratio is preferably 1.07 or higher, and more preferably 1.09 or higher. Furthermore, the T1 / T2 ratio is preferably 1.35 or lower, and more preferably 1.30 or lower. Having the T1 / T2 ratio within the above range is preferable from the viewpoint of the flexibility of the activated carbon fibers.

[0032] Of the pore volume of the activated carbon fibers of the present invention, the pore volume of pores with a diameter of 0.7 nm or more and less than 1.3 nm is 0.08 cm³. ３ / g or more 0.22cm ３ It is less than / g and 0.10cm ３ / g or more 0.21cm ３ It is preferable that the amount is less than or equal to / g. Also, the pore volume of a pore diameter of 1.3 nm to 2.3 nm is 0.02 cm³. ３ / g or more 0.20cm ３ It is less than / g and 0.03 cm ３ / g or more 0.15cm ３ It is preferable that the volume is less than or equal to / g. When the volume of micropores with a pore diameter of 0.7 nm or more and less than 1.3 nm is within the above range, and the volume of pores with a pore diameter of 1.3 nm or more and less than 2.3 nm is within the above range, the diffusion of the adsorbed molecules into the pores is promoted, resulting in excellent adsorption capacity. On the other hand, activated carbon fiber formation bodies formed from activated carbon fibers with a pore volume within the above range tend to have low flexibility, making it difficult to incorporate them into devices. However, in the present invention, flexibility can be improved by setting the degree of irregularity R of the activated carbon fibers to a specific range. The pore volume is calculated by analyzing the adsorption isotherm based on nitrogen adsorption as described in the examples using the GCMC method.

[0033] The activated carbon fibers of the present invention are obtained by activating (activating) carbon fibers, and the method of production is not particularly limited, but it is preferable to use polyphenylene ether (hereinafter sometimes referred to as "PPE") fibers as a precursor. As an example of a method for producing activated carbon fibers, they can be produced by the method for producing activated carbon fibers described later.

[0034] 2. Activated Carbon Fiber Molded Articles The activated carbon fiber molded articles of the present invention are made of the activated carbon fibers. Examples of activated carbon fiber molded articles include activated carbon fiber paper, activated carbon fiber fabrics, activated carbon fiber knitted fabrics, activated carbon fiber nonwoven fabrics, etc. Among these, activated carbon fiber nonwoven fabrics are preferred due to their high versatility. For example, activated carbon fiber nonwoven fabrics can be wound around a cylinder to form cylindrical activated carbon fiber nonwoven fabric elements, which are used as adsorbents in organic solvent adsorption / desorption processing devices and as adsorbents in organic solvent recovery systems using the organic solvent adsorption / desorption processing devices.

[0035] The basis weight of the activated carbon fiber molded product (e.g., nonwoven fabric) is not particularly limited and can be determined appropriately depending on the application, but from the viewpoint of processability, adsorption characteristics and physical properties of the activated carbon fibers produced, 10 g / m² is recommended. ２ The above is preferable, and 30 g / m ２ The above is more preferable, 100 g / m ２ The above is even more preferable. Also, 800 g / m ２ The following is preferable: 600 g / m ２ The following is more preferable: 500 g / m ２ The following is even more preferable.

[0036] The thickness of the activated carbon fiber molded body (e.g., nonwoven fabric) is not particularly limited and can be determined appropriately depending on the application, but from the viewpoint of processability, adsorption characteristics and physical properties, it is preferably 0.1 mm to 12.0 mm, and more preferably 0.2 mm to 6.0 mm.

[0037] The bulk density of the activated carbon fiber molded body (e.g., nonwoven fabric) is not particularly limited, but is 100 kg / m³. ３ More than 300kg / m ３ The following is preferable: 120 kg / m ３ More than 150kg / m ３The following are preferable.

[0038] The flexibility of the activated carbon fiber molded body (e.g., nonwoven fabric) may be 5 mN or more and 200 mN or less, preferably 10 mN or more and 150 mN or less, more preferably 10 mN or more and 100 mN or less, and even more preferably 20 mN or more and 80 mN or less. This range is preferable because it allows for proper integration into the device without cracking or breaking.

[0039] The pressure loss coefficient when air is passed through an activated carbon fiber molded material (e.g., nonwoven fabric) at a linear velocity of 30 cm / second is 0.80 mmAq·s / cm ２ Preferably, the following is true: 0.60 mmAq·s / cm ２ The following is more preferable: 0.40 mmAq·s / cm ２ The following is even more preferable: The lower limit of the number of pressure loss units is typically 0.10 mmAq·s / cm ２ That's all.

[0040] 3. Method for producing activated carbon fibers The activated carbon fibers of the present invention can be obtained by activating carbon fibers that have been carbonized from raw material PPE fibers.

[0041] The carbon fiber is obtained using the raw material PPE fiber as the raw material. Specifically, the carbon fiber can be obtained by carbonizing the PPE fiber after it has been treated in at least one of the following processes: infusibility treatment (heat treatment in air at 120 to 220°C for 0.1 to 5.0 hours) and flame-retardant treatment (heat treatment in air at 220 to 300°C for 0.1 to 5.0 hours). Here, "in air" refers to an environment that is not specially controlled. Furthermore, the heating rate to reach the treatment temperature is preferably 0.01 to 20°C / min, and more preferably 0.1 to 10°C / min. By using the above treatment temperature, treatment time, and heating rate, a flame-retardant structure is formed in the PPE fiber.

[0042] The carbonization (carbonization treatment) can be carried out by known methods, specifically by heating in the presence of an inert gas. Examples of inert gases include nitrogen and argon. The heating temperature is usually 300 to 2500°C, preferably 500 to 1500°C. The heating time is usually 0.1 to 10 hours, preferably 0.5 to 5 hours.

[0043] The aforementioned activation (activation treatment) can be carried out by known methods, specifically including gas activation and chemical activation methods, but gas activation is preferred from the viewpoint of improving fiber strength and purity.

[0044] In the gas activation method, the carbon fibers are activated by bringing an activating gas into contact with them. Examples of activating gases include water vapor, air, carbon monoxide, carbon dioxide, hydrogen chloride, oxygen, or mixtures thereof. The temperature during gas activation is usually 600 to 1200°C, preferably 800 to 1000°C. The time for gas activation is usually 0.2 to 10 hours, preferably 0.5 to 3 hours.

[0045] In the chemical activation method, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; alkaline earth metal hydroxides such as calcium hydroxide; inorganic acids such as boric acid, phosphoric acid, sulfuric acid, and hydrochloric acid; inorganic salts such as zinc chloride, etc., are brought into contact with the carbon fibers to activate them. The temperature during chemical activation is usually 400 to 1000°C, preferably 500 to 800°C. The time during chemical activation is usually 0.2 to 5 hours, preferably 0.5 to 5 hours.

[0046] The following explains the raw material, PPE fiber.

[0047] <Raw PPE Fibers> The raw PPE fibers have an irregular cross-section and contain PPE components. The degree of irregularity R of the fibers of the raw PPE fibers, as shown in Formula 1 above, can be appropriately selected according to the degree of irregularity R of the activated carbon fibers required, but it is preferably 1.10 or more and 2.00 or less.

[0048] The PPE components contained in the raw PPE fibers are not particularly limited and include those commonly used in this field. Specifically, examples include homopolymers having repeating units represented by the following general formula (1), copolymers containing two or more different repeating units of general formula (1), and copolymers having repeating units of general formula (1) and repeating units other than general formula (1).

[0049]

[0050] R in the general formula (1) １ , R ２ Examples include C1-C10 alkyl groups such as hydrogen atoms, methyl groups, ethyl groups, propyl groups, isopropyl groups, n-butyl groups, isobutyl groups, t-butyl groups, pentyl groups, cyclopentyl groups, hexyl groups, cyclohexyl groups, octyl groups, and decyl groups, C6-C10 aryl groups such as phenyl groups, 4-methylphenyl groups, 1-naphthyl groups, and 2-naphthyl groups, and C7-C10 aralkyl groups such as benzyl groups, 2-phenylethyl groups, and 1-phenylethyl groups. Among these, R １ , R ２ Preferably, the component is a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

[0051] R in the general formula (1) ３ Examples include C1-C10 alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, octyl, and decyl groups; C6-C10 aryl groups such as phenyl, 4-methylphenyl, 1-naphthyl, and 2-naphthyl groups; and C7-C10 aralkyl groups such as benzyl, 2-phenylethyl, and 1-phenylethyl groups. Among these, R ３ A methyl group is preferred as the component.

[0052] Specific examples of the repeating unit of the general formula (1) include repeating units derived from 2,6-dimethyl-1,4-phenylene ether, 2,6-diethyl-1,4-phenylene ether, 2-methyl-6-ethyl-1,4-phenylene ether, and 2,6-dipropyl-1,4-phenylene ether. Among these, the repeating unit derived from 2,6-dimethyl-1,4-phenylene ether is preferred.

[0053] Furthermore, the PPE may contain repeating units other than those of general formula (1) as long as it does not impair the effects of the present invention. The content of such repeating units other than those of general formula (1) is not particularly limited as long as it does not impair the effects of the present invention, but for example, it is preferably about 5 mol% or less in the copolymer, and more preferably it is not included.

[0054] The PPE component preferably has a dislocation structure connected by ortho bonds within a repeating unit that is continuous by para bonds. Examples of the repeating unit that is continuous by para bonds include the repeating unit represented by the above general formula (1), and examples of the dislocation structure include the following general formula (2): (In the formula, R １ , R ２ Each is independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, which may have substituents, and R ３ Each of these is independently a hydrocarbon group having 1 to 10 carbon atoms, which may have substituents, and R ３ ' is the aforementioned R ３ One possible rearrangement structure is represented by (a divalent group from which one hydrogen atom has been removed).

[0055] In the above general formula (2), R １ ~R ３ Examples include those similar to those in general formula (1) above. The "~" in general formula (2) indicates that the structure beyond it is not particularly limited. The "~" portion may be formed from phenylene ether units connected by para bonds, or it may have a portion that is partially bonded at the ortho position.

[0056] The aforementioned R３ ' is the aforementioned R ３ This represents a divalent group from which one hydrogen atom has been removed, and it is preferably a methylene group.

[0057] The PPE component having the aforementioned rearrangement structure is preferably a homopolymer having repeating units of general formula (1), a copolymer containing two or more different repeating units of general formula (1), or a copolymer containing repeating units of general formula (1) and repeating units other than general formula (1) that has a rearrangement structure represented by general formula (2).

[0058] If the PPE component has a dislocation structure, the amount of the dislocation structure (hereinafter also referred to as "dislocation amount") is preferably 0.05 mol% or more, preferably 0.1 mol% or more, and more preferably 0.5 mol% or more, relative to the total structural units constituting the PPE component. Furthermore, the dislocation amount is preferably 15 mol% or less, more preferably 10 mol% or less, and even more preferably 8 mol% or less. Having the dislocation amount in the PPE component having a dislocation structure within the above range is preferable because it improves fluidity to a degree that allows for melt molding, enabling the formation of melt-spun fibers.

[0059] The aforementioned dislocation structure is observed in the nuclear magnetic resonance spectrum ( １ In 1H-NMR measurements, it is preferable to show peaks in the ranges of 3.8–4.0 ppm and 6.8–7.0 ppm. Typically, PPE shows a peak around 6.4–6.6 ppm, which is a peak originating from the hydrogen atoms at positions 3 and 5 of the benzene ring in the PPE main chain. PPE having the rearrangement structure shows peaks in the ranges of 3.8–4.0 ppm and 6.8–7.0 ppm, in addition to the peak around 6.4–6.6 ppm. The chemical shift at 3.8–4.0 ppm is due to R in the rearrangement structure. ３ This originates from the proton of the divalent group (e.g., methylene group) indicated by ', and the chemical shift of 6.8 to 7.0 ppm is due to the R at the 3 and 5 positions of PPE in the rearrangement structure. １ , R ２ It originates from the protons of the group (for example, the hydrogen atoms at positions 3 and 5 of the benzene ring bonded to the ortho position via a methylene group).

[0060] The molecular weight of the PPE is not particularly limited, but the weight-average molecular weight (Mw) is preferably 10,000 to 100,000, and more preferably 50,000 to 80,000. The number-average molecular weight (Mn) is preferably 7,000 to 30,000, and more preferably 8,000 to 20,000. The molecular weight dispersion (Mw / Mn) is preferably 3.5 to 8.0, and more preferably 4.0 to 6.0.

[0061] The raw material PPE fiber used in the present invention may contain resin components other than the PPE component. Examples of resin components other than PPE include polyolefins such as polystyrene, polyethylene, and 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 polycarbonate. However, the content of these components is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably none (0% by mass).

[0062] Furthermore, the raw material PPE fiber used in the present invention may also contain additives such as lubricants, plasticizers, antioxidants, ultraviolet absorbers, pigments, dyes, and antistatic agents, to the extent that they do not impair the effects of the present invention.

[0063] Furthermore, in the raw material PPE fiber used in the present invention, the PPE content is preferably 95% by mass or more of the total components forming the fiber, more preferably 98% by mass or more, and even more preferably substantially composed of only PPE (100% by mass). By having the PPE content in the fiber within the above range, excellent mechanical strength and processability can be obtained.

[0064] <Method for producing raw PPE fibers> Raw PPE fibers can be produced by various methods such as melt spinning, dry spinning, and wet spinning. Among these, melt spinning is preferred because it allows for high productivity.

[0065] An example of manufacturing PPE melt-spun fibers as a raw material will be explained using Figure 1. The raw material, PPE, is fed from the hopper 1 in Figure 1 into an extruder 2 equipped with a cylinder and a screw. The molten PPE is discharged at a rate measured by a gear pump 3, passes through a filter material 4 composed of fine sand or the like, and is discharged from a spinning nozzle 5 to obtain melt-spun fibers. The extruder may be equipped with a degassing vent 10, and extrusion may be performed while degassing. An inert gas may be introduced into the extruder 2 at the end of the degassing vent 10 to prevent oxygen from entering, or a vacuum pump may be attached. Furthermore, it is preferable to install a filter 6 made of a metal nonwoven fabric or the like on the filter material 4. Installing the filter 6 is preferable because it can remove foreign matter in advance and prevent clogging of the filter material 4.

[0066] Furthermore, a heat retention space 7 is provided directly below the spinning nozzle 5, and it is preferable to introduce an inert gas such as nitrogen 8 into this area during spinning, from the viewpoint of suppressing nozzle clogging due to oxidative crosslinking. It is even more preferable to introduce a heated inert gas using a heating torch 9. The temperature of the heated inert gas is preferably 100°C to 500°C, and more preferably 200°C to 400°C.

[0067] The end of the degassing vent 10 may be an open vent with nothing attached, or it may be a vacuum vent that actively degasssed by suction by connecting a vacuum pump. When performing vacuum venting, a trap to collect volatile components may be provided between the vent and the vacuum pump. In the present invention, a vacuum vent is preferred.

[0068] The spinning speed is not particularly limited and can be set appropriately according to the required fineness, etc., but in order to stably obtain fine fibers, a speed of about 100 m / min or more is preferred, and about 200 m / min or more is more preferred. Furthermore, a speed of about 5000 m / min or less is preferred, and about 4000 m / min or less is more preferred.

[0069] The single-hole discharge rate of the spinning nozzle is preferably 3.0 g / min or less, more preferably 2.8 g / min or less, and even more preferably 2.6 g / min or less. The lower limit of the single-hole discharge rate is not particularly limited, but is preferably 0.05 g / min or more, more preferably 0.1 g / min or more, and even more preferably 0.12 g / min or more.

[0070] The shape of the spinning nozzle hole can be appropriately changed according to the desired degree of irregularity of the resulting PPE fiber, and is not particularly limited, but a nozzle hole shape with an irregularity R' of 1.15 or more is preferred. Here, the irregularity R' of the nozzle hole of the spinning nozzle can be calculated by the following formula 1': Irregularity R' = Circumscribed circle diameter / Inscribed circle diameter (Formula 1') (In the formula, the circumscribed circle diameter is the diameter of the circle circumscribed around the cross-section of the nozzle hole, and the inscribed circle diameter is the diameter of the circle inscribed around the cross-section of the nozzle hole.)

[0071] Furthermore, it is preferable that the ratio of the outer circumference of the nozzle hole shape (outer circumference of the nozzle hole / outer circumference of a perfect circle having the same cross-sectional area as the nozzle hole cross-sectional area) is 1.05 or greater.

[0072] When spinning using a nozzle with an irregular cross-section, it is known that the yarn tends to return to a circular shape due to surface tension once it exits the nozzle hole. Therefore, it is preferable to have a nozzle shape that is larger than the desired degree of irregularity R or circumference ratio.

[0073] Figure 4 shows an example of the nozzle hole shape when forming a six-lobed cross-section. As shown in Figure 4, the shape is such that six slits are arranged radially from the center of the circumscribed circle of the nozzle hole. The slit width 14 is set appropriately according to the desired degree of irregularity, but is preferably about 0.05 to 0.6 mm, and more preferably about 0.08 to 0.5 mm.

[0074] Examples of PPE used as a raw material include homopolymers having the repeating unit of general formula (1), copolymers containing two or more different repeating units of general formula (1), and copolymers having the repeating unit of general formula (1) and repeating units other than general formula (1). The content of repeating units other than general formula (1) in the copolymer can be as described above. Among these, homopolymers having the repeating unit of general formula (1) are preferred.

[0075] Examples of homopolymers having the repeating unit of the general formula (1) include poly(2,6-dimethyl-1,4-phenylene ether), poly(2,6-diethyl-1,4-phenylene ether), poly(2-methyl-6-ethyl-1,4-phenylene ether), and poly(2,6-dipropyl-1,4-phenylene ether), but among these, poly(2,6-dimethyl-1,4-phenylene ether) is preferred.

[0076] As the poly(2,6-dimethyl-1,4-phenylene ether) mentioned above, commercially available products can also be suitably used. Examples include PPO640, PPO646, and PPOSA120 from SABIC Innovative Plastics, PX100F from Mitsubishi Engineering Plastics Corporation, LNX035 from Blue Star Group, and Zylon (trademark registered) S201A and Zylon (trademark registered) S202A from Asahi Kasei Chemicals Corporation.

[0077] Furthermore, when melting PPE, the melt viscosity can be reduced by mixing PPE with high Tg and low Tg.

[0078] 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. While there is no particular upper limit to the glass transition temperature, it is preferably 230°C or lower. Having the glass transition temperature of the raw material PPE within this range is preferable because it allows for the acquisition of PPE fibers with high heat resistance.

[0079] The glass transition temperature of the PPE component having a low glass transition temperature is preferably less than 170°C. Adding PPE with a glass transition temperature of less than 170°C reduces the melt viscosity and improves fluidity.

[0080] The content of PPE having a glass transition temperature of 170°C or higher is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, in the PPE component of the raw material. Furthermore, there is no particular upper limit to the content of PPE having a glass transition temperature of 170°C or higher, but it is preferably 100% by mass or less. In the present invention, including PPE with a high glass transition temperature (i.e., high molecular weight) within the above range is preferable because it results in excellent mechanical strength, heat resistance, chemical resistance, flame retardancy, etc. of the resulting PPE molten fibers.

[0081] Furthermore, along with the raw material PPE, the material may also contain resin components and additives other than PPE. The resin components and additives other than PPE are as described above. The content of resin components other than PPE is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably none (0% by mass).

[0082] As the extruder equipped with the cylinder and screw, a single-screw extruder or a twin-screw extruder, which are commonly used in this field, can be used. In the present invention, it is preferable to use a twin-screw extruder.

[0083] The peripheral speed of the screw is not particularly limited and can be within the range commonly used in this field. However, when forming fibers using a PPE component having a dislocation structure, the peripheral speed of the screw must be such that the dislocation reaction of the raw material PPE occurs, and is preferably 3.6 m / min or more, more preferably 3.7 m / min or more, and even more preferably 3.8 m / min or more. Furthermore, the upper limit of the peripheral speed of the screw is not particularly limited, but is preferably 94.2 m / min or less. In the present invention, by increasing the screw rotation speed to 3.6 m / min or more, a high shear force can be applied to the raw material PPE in the cylinder, and as a result, the molecular chains of PPE can be cleaved and PPE having a dislocation structure can be formed.

[0084] If the temperature inside the cylinder is too low, the fluidity of the resin will be poor, and if it is too high, although the fluidity will improve, foaming will occur due to thermal decomposition of the resin. Therefore, it is necessary to select a processing temperature that strikes a balance between these two factors. For example, the temperature inside the cylinder is preferably between 250°C and 350°C, and more preferably between 280°C and 330°C.

[0085] The surface temperature of the spinning nozzle is not particularly limited, but is preferably 300°C or higher, more preferably 320°C or higher, and even more preferably 330°C or higher. A nozzle surface temperature within this range is preferable because it results in fluidity suitable for spinning.

[0086] The raw material PPE fiber may be short fibers. These short fibers can be obtained, for example, by cutting fibers that have been twisted together to form a tow.

[0087] 4. Method for Manufacturing an Activated Carbon Fiber Molded Article The method for manufacturing an activated carbon fiber molded article of the present invention involves activating a carbonized molded article, which is a fiber molded article made from raw PPE fibers that has been carbonized. As the method for manufacturing the carbonized molded article, the method described above for manufacturing activated carbon fibers can be suitably used.

[0088] Furthermore, the raw material PPE fiber can be the same as that described in the method for producing activated carbon fiber. Below, a PPE nonwoven fabric will be described as an example of a fiber molded product.

[0089] <PPE Nonwoven Fabric> The PPE nonwoven fabric is a nonwoven fabric containing the raw material PPE fibers described above. The same raw material PPE fibers as described above can be used for the PPE nonwoven fabric. The method for manufacturing the PPE nonwoven fabric is not particularly limited, and methods commonly used in this field can be appropriately adopted. Examples of methods for manufacturing nonwoven fabrics include the spunbond method, meltblown method, spunlace method, needle punch method, thermal bond method, and chemical bond method. Among these, the needle punch method is preferred.

[0090] The activated carbon fibers and activated carbon fiber molded articles of the present invention are suitably used, for example, for the recovery of organic solvents such as dichloromethane; the removal of chlorine compounds such as trihalomethanes; the removal of malodorous gases, NOx, and SOx; and the removal of heavy metals such as lead, arsenic, and manganese.

[0091] 5. Organic Solvent Adsorption / Desorption Apparatus, Organic Solvent Recovery System, Organic Solvent Adsorption / Desorption Treatment Method, and Organic Solvent Recovery Method The organic solvent recovery system of the present invention can recover organic solvents from a fluid to be treated. The fluid to be treated refers to a liquid to be treated, such as wastewater, or a gas to be treated, such as exhaust gas. In the organic solvent recovery system of the present invention, the object to be treated may be a liquid or a gas.

[0092] An embodiment of the organic solvent recovery system of the present invention is illustrated in Figure 5. The organic solvent recovery system 100 includes an organic solvent adsorption / desorption processing device 119 having adsorption tanks 2A and 2B. Inside the adsorption tanks 2A and 2B, there are removable activated carbon fiber nonwoven fabric elements 106, which are hollow cylindrical structures in which activated carbon fiber nonwoven fabric 107 (adsorbent) is wound in layers around a cylindrical cage-shaped core, with their outer surfaces fixed by a wire mesh. Figure 5 illustrates an organic solvent recovery system 100 having two adsorption tanks, but there may be one adsorption tank or three or more. The bottom of the activated carbon fiber nonwoven fabric element 106 is closed.

[0093] Figure 5 describes the case where adsorption tank 2A ​​is performing adsorption processing and adsorption tank 2B is performing desorption processing. First, the adsorption process will be described. The solvent mixed fluid (fluid to be treated) 101 containing an organic solvent passes through the pre-filter 102 and is sent to the adsorption tank 2A ​​via the lower damper 104 by the blower 103. There, the organic solvent in the fluid to be treated is adsorbed by the activated carbon fiber nonwoven fabric 107 of the activated carbon fiber nonwoven fabric element 106, and the clean air is discharged from the system out of the exhaust port 110 of the adsorption tank 2A ​​via the upper damper 108. At this time, the automatic valve 112 of the water vapor supply line 111 is closed.

[0094] Next, the desorption process will be described. Steam supplied from the steam supply line 111 is supplied to the adsorption tank 2B via the automatic valve 113, where the organic solvent in the fluid to be treated that has been adsorbed onto the activated carbon fiber nonwoven fabric 107 of the activated carbon fiber nonwoven fabric element 106 is desorbed and regenerated. The condensate and the uncondensed steam containing organic solvent components in the fluid to be treated are sent to the condenser 115 via the desorption fluid line 114, where the uncondensed steam containing organic solvent components in the fluid to be treated is condensed. From the condenser 115, the condensate containing a high concentration of organic solvent is sent to the separator 117. At this time, the lower damper 105 and the upper damper 109 are closed. The fluid containing organic solvent components that remains in the separator 117 is returned to the fluid to be treated 101 again via the return fluid line 118. The organic solvent recovery device in the organic solvent recovery system includes, for example, the condenser 115, the cooling water supply line 116, and the separator 117 shown in Figure 5, but is not limited to these.

[0095] The organic solvent adsorption / desorption apparatus, organic solvent recovery system, organic solvent adsorption / desorption method, and organic solvent recovery method of the present invention can employ known apparatuses, systems, processing methods, and recovery methods, except that the activated carbon fiber molded body of the present invention is used as the adsorbent. For example, the apparatuses, systems, processing methods, and recovery methods described in Japanese Patent Publication No. 6-55254, Japanese Patent Application Publication No. 2004-105806, and Japanese Patent Application Publication No. 2013-111552 can be employed.

[0096] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The evaluation methods for physical properties, etc., in the following examples are as follows, and unless otherwise specified, the measurement of physical properties, etc., means measurement at room temperature of 20°C / relative humidity of 65%.

[0097] (1) Fineness and single filament fineness were measured according to the method described in JIS L-1095 9.4.1. Single filament fineness was calculated by dividing the fineness by the number of filaments.

[0098] (2) Glass transition temperature (Tg) Using a differential scanning calorimetry analyzer (model: DSC-Q100) manufactured by TA Instruments Inc., 2 mg of PPE fiber was measured from 30°C to 250°C in a nitrogen atmosphere at a heating rate of 10°C / min. The temperature at the intersection of the extension of the baseline below the glass transition temperature and the tangent line showing the maximum slope in the transition region was defined as the glass transition temperature (Tg).

[0099] (3) The amount of dislocation structure in the raw PPE fiber at a resonance frequency of 600 MHz １ The measurement was performed using 1H-NMR. A BRUKER NMR spectrometer (model name: AVANCE-NEO600) was used, and the measurement was performed as follows: 10 mg of PPE fiber obtained in the examples and comparative examples was dissolved in deuterated chloroform, and the solution was packed into an NMR tube within 2 hours for measurement. Deuterated chloroform was used as the locking solvent, with a waiting time of 1 second, a data acquisition time of 4 seconds, and 64 integration cycles. Deuterated benzene may also be used as the solvent. The rearrangement structure amount was analyzed as follows: R at the 3 and 5 positions of PPE. １ , R ２ Peaks originating from the proton of the base and R in the dislocation structure ３ The peak integrals of the peaks originating from the protons of the divalent group (methylene group, etc.) indicated by ' were denoted as A and B, and the rearrangement structure weight was calculated using the following formula: Rearrangement structure weight (mol%) = (B / (A + B)) × 100

[0100] (4) Peripheral speed of the screw The peripheral speed of the screw was determined by the following formula: Peripheral speed of the screw (m / min) = Screw diameter (mm) × 0.00314 × Screw rotation speed (rpm)

[0101] (5) Degree of Irregularity R The degree of irregularity R of the activated carbon fiber was determined by observing microscopic images using a scanning electron microscope (product name: SU1510, manufactured by Hitachi High-Technologies Corporation). From these microscopic images, the diameters of the circumscribed circle and the inscribed circle were read at more than 50 locations on the cross-section, and the degree of irregularity R (diameter of circumscribed circle / diameter of inscribed circle) was calculated. The average value of the obtained values ​​was taken as the degree of irregularity R.

[0102] (6) Perimeter length and cross-sectional area of ​​the cross-section The cross-sectional area and perimeter length of the cross-section of the activated carbon fiber were determined by observing microscope images using a scanning electron microscope (product name: SU1510, manufactured by Hitachi High-Technologies Corporation), and averaging the cross-sectional area and perimeter length of the cross-section read from 50 or more points in the microscope image. The perimeter length ratio, which is the ratio to the perimeter length when the cross-sectional shape is a round cross-section and the area is the same, was averaged. Image processing software ImageJ was used for image analysis.

[0103] (7) Measure the mass per unit area of ​​the basis weight nonwoven fabric sample in units of g / m ２ The mass was determined using the following method. The mass was measured in an air-filled, completely dry state after treatment at 100°C for 0.5 hours.

[0104] (8) A load of 15 g was applied to the nonwoven fabric sample, and the thickness was measured and determined in mm. The thickness was the average value obtained by measuring at two or more different locations on the nonwoven fabric sample.

[0105] (9) Bulk density From the above measured values ​​of basis weight and thickness, the bulk density of the nonwoven fabric sample is calculated in units of kg / m ３ This was calculated using the following formula: Bulk density (kg / m³). ３ ) = Basis weight (g / m ２ ) ÷ thickness (mm)

[0106] (10) Pressure loss coefficient of activated carbon fiber nonwoven fabric. The activated carbon fiber nonwoven fabric was cut to a size of 35 mm x 35 mm or larger and sandwiched between plastic plates cut to 30 mm x 30 mm. Air at 25°C and 50% relative humidity RH was supplied to the cylindrical tube at a linear velocity of 30 cm / sec, and the static pressure difference (mmAq) between the primary and secondary sides of the filled nonwoven fabric was measured. From the obtained static pressure difference, the pressure loss coefficient of the nonwoven fabric (mmAq·s / cm) was calculated using the following formula. ２ The pressure loss coefficient was calculated as follows: Pressure loss coefficient = Pressure loss (mmAq) ÷ Linear velocity (cm / s) ÷ Thickness (cm)

[0107] (11) Flexibility of activated carbon fiber nonwoven fabric The activated carbon fiber nonwoven fabric was wrapped around a cylinder with a diameter of 50 mm and evaluated according to the following evaluation criteria. ○: No cracks or breaks occurred. ×: Cracks or breaks occurred.

[0108] (12) Flexibility of activated carbon fiber nonwoven fabric The activated carbon fiber nonwoven fabric was cut into 25 mm x 35 mm pieces and its flexibility was measured using a flexibility tester (product name: Digital Gahl Flexibility Tester, manufactured by Hitachi High-Technologies Corporation). A higher numerical value indicates greater flexibility. Note that the flexibility of the activated carbon fiber nonwoven fabrics in Comparative Examples 1 to 3 was extremely low and could not be measured.

[0109] (13) A sample of activated carbon fiber nonwoven fabric was taken with a mass of 0.1 g using the GCMC method. Using the taken sample, the nitrogen adsorption isotherm at 77 K was measured using a BELSORP MAX II manufactured by Microtrac-Bel. The obtained adsorption isotherm was analyzed using the GCMC method with the activated carbon adsorbent set to graphite carbon and the pore shape set to a slit model to determine the pore volume for pores with a diameter of 0.7 nm or more and less than 1.3 nm, and the pore volume for pores with a diameter of 1.3 nm or more and less than 2.3 nm.

[0110] Example 1 Poly(2,6-dimethyl-1,4-phenylene ether) (PPO (trademark registered) 640, glass transition temperature (Tg): 221°C, manufactured by SABIC Innovative Plastic) was extruded using a twin-screw extruder manufactured by Technovel Co., Ltd. (product name: KZW15TW-30MG). The twin-screw extruder has four cylinder zones, and the cylinders from the hopper side were designated as cylinders 1, 2, 3, and 4. Cylinder 1 was set to 280°C, and cylinders 2-4 and the cylinder head were set to 300°C. The screw rotation speed was set to 700 rpm, and the peripheral speed of the screw was 33.0 m / min. A vent was attached to cylinder 3 and vacuum was applied.

[0111] A gear pump was installed downstream of the extruder, and the polymer was extruded through a metal nonwoven fabric filter (product name: NF-10, manufactured by Nippon Seisen Co., Ltd.) into a nozzle (diameter of the circumscribed circle of the nozzle hole: 1.40 mm, diameter of the inscribed circle of the nozzle hole: 0.49 mm, nozzle hole irregularity R': 2.86, nozzle hole circumference ratio: 1.71, slit width: 0.35 mm, nozzle shape: four slits arranged radially from the center of the circumscribed circle (four-lobed cross section), nozzle hole land length: 4.0 mm, number of nozzle holes: 48) (total discharge rate: 50.0 g / min). The nozzle surface temperature was set to 340°C. The polymer discharged from the nozzle was wound up at a spinning speed of 316 m / min to obtain PPE fibers. The obtained PPE fibers had a single filament fineness of 33 dtex, an irregularity of 1.15, a circumference ratio of 1.10, and a dislocation structure content of 1.44 mol%.

[0112] The obtained PPE fibers were crimped, cut to a length of 76 mm, and then punched using a needle punching machine to achieve a needle density of 100 needles / cm². ２ The fabric was then treated on both sides with a needle depth of 2 mm (front) and 7 mm (back) to obtain a PPE nonwoven fabric.

[0113] The obtained PPE nonwoven fabric was heated in air from room temperature to 200°C at a heating rate of 10°C / min. Then, the temperature was gradually increased from 200°C to 210°C over 72 minutes, and held at 210°C for 24 minutes to perform infusibility treatment. Subsequently, the temperature was gradually increased from 225°C to 280°C over 72 minutes (heating rate: 5°C / min or less), and held at 280°C for 24 minutes to perform flame-retardant treatment, thereby obtaining flame-retardant PPE nonwoven fabric.

[0114] The obtained flame-retardant PPE nonwoven fabric was subsequently subjected to carbonization treatment in nitrogen at 900°C for 1 hour, and then activated in nitrogen with 11% by volume of water vapor at 900°C for 1 hour to obtain activated carbon fiber nonwoven fabric. The degree of irregularity and perimeter length ratio of the activated carbon fibers in the obtained activated carbon fiber nonwoven fabric were the same as those of the raw material PPE fibers. The evaluation results of the obtained activated carbon fiber nonwoven fabric are shown in Table 1.

[0115] Example 2 In forming PPE fibers, the nozzle shape was changed to one with eight slits arranged radially from the center of the circumscribed circle, and the slit width was changed by 0.15 mm. Except for these changes, PPE fibers were obtained in the same manner as in Example 1. Using the same method as in Example 1, an activated carbon fiber molded article (nonwoven fabric) consisting of activated carbon fibers with different degrees of irregularity was obtained. The evaluation results are shown in Table 1.

[0116] Example 3: PPE fibers were obtained using the same method as in Example 1, except that the slit width was changed by 0.3 mm. An activated carbon fiber molded article (nonwoven fabric) consisting of activated carbon fibers with different degrees of irregularity was obtained using the same method as in Example 1. The evaluation results are shown in Table 1.

[0117] Example 4 In forming PPE fibers, the nozzle shape was changed to one with eight slits arranged radially from the center of the circumscribed circle, and the slit width was changed by 0.10 mm. Except for these changes, PPE fibers were obtained in the same manner as in Example 1. Using the same method as in Example 1, an activated carbon fiber molded article (nonwoven fabric) consisting of activated carbon fibers with different degrees of irregularity was obtained. The evaluation results for each are shown in Table 1.

[0118] Comparative Example 1: PPE fibers were obtained using the same method as in Example 1, except that the nozzle was changed to a circular nozzle with a diameter of 1.40 mm. An activated carbon fiber nonwoven fabric was obtained using the same method as in Example 1, consisting of activated carbon fibers with different degrees of irregularity. The flexibility of the nonwoven fabric was extremely low. The evaluation results are shown in Table 1.

[0119] Comparative Example 2: In forming PPE fibers, the nozzle shape was changed to one with eight slits arranged radially from the center of the circumscribed circle, and the slit width was changed by 0.2 mm. PPE fibers were obtained using the same method as in Example 1. An activated carbon fiber nonwoven fabric was obtained using the same method as in Example 1, consisting of activated carbon fibers with different degrees of irregularity. The flexibility of the nonwoven fabric was extremely low. The evaluation results are shown in Table 1.

[0120] Comparative Example 3: PPE fibers were obtained using the same method as in Example 1, except that the slit width was changed by 0.25 mm. An activated carbon fiber nonwoven fabric was obtained using the same method as in Example 1, consisting of activated carbon fibers with different degrees of irregularity. The flexibility of the nonwoven fabric was extremely low. The evaluation results are shown in Table 1.

[0121]

[0122] The activated carbon fiber nonwoven fabrics of Examples 1 to 4 exhibited excellent flexibility. It is believed that the activated carbon fibers constituting the nonwoven fabric also possess flexibility due to the fabric's inherent flexibility. On the other hand, cracks developed in the activated carbon fiber nonwoven fabrics of Comparative Examples 1 to 3.

[0123] The activated carbon fibers having a uniquely shaped cross-section according to the present invention are suitably used as adsorbents with excellent adsorption performance and physical properties.

[0124] 1 Hopper 2 Extruder 3 Gear pump 4 Filter media 5 Spinning nozzle 6 Filter 7 Insulated space 8 Inert gas introduction 9 Heating torch 10 Degassing vent 11 Cross-section of activated carbon fiber 12 Circumscribed circle 13 Inscribed circle 14 Slit width 100 Organic solvent recovery system 2A Adsorption tank 2B Adsorption tank 101 Solvent mixed fluid containing organic solvent (fluid to be treated) 102 Pre-filter 103 Blower 104 Lower damper 105 Lower damper 106 Activated carbon fiber nonwoven fabric element 107 Activated carbon fiber nonwoven fabric 108 Upper damper 109 Upper damper 110 Exhaust port 111 Water vapor supply line 112 Automatic valve 113 Automatic valve 114 Desorption fluid line 115 Condenser 116 Cooling water supply line 117 Separator 118 Return fluid line 119 Organic solvent adsorption / desorption treatment device

Claims

1. The degree of irregularity R of the fiber shown in formula 1 below is 1.10 or more and 2.00 or less, and the pore volume of the pore diameter is 0.7 nm or more and less than 1.3 nm is 0.08 cm³. ３ / g or more 0.22cm ３ The amount is less than / g, and the pore volume is 0.02 cm³ with a pore diameter of 1.3 nm to 2.3 nm. ３ / g or more 0.20cm ３ Activated carbon fibers with a density of less than or equal to / g. Deformity R = Circumscribed circle diameter / Inscribed circle diameter (Equation 1) (In the equation, the circumscribed circle diameter is the diameter of the circle circumscribed around the fiber cross-section, and the inscribed circle diameter is the diameter of the circle inscribed around the fiber cross-section.) 2. The activated carbon fiber according to claim 1, wherein when the outer circumference length of the cross-section of the activated carbon fiber is T1 and the outer circumference length of a round cross-section fiber having the same fiber cross-sectional area as the activated carbon fiber is T2, the outer circumference length ratio (T1 / T2) is 1.05 or more and 1.40 or less.

3. An activated carbon fiber molded article comprising the activated carbon fibers described in claim 1, wherein the degree of flexibility is 5 mN or more and 200 mN or less.

4. The activated carbon fiber molded article according to claim 3, wherein the activated carbon fiber is an activated carbon fiber nonwoven fabric.

5. 100 kg / m ３ More than 300kg / m ３ It has the following bulk density and a pressure loss coefficient of 0.80 mmAq·s / cm when air is passed through it at a linear velocity of 30 cm / s. ２ The activated carbon fiber molded article according to claim 4, which is as follows:

6. The activated carbon fiber according to claim 1 or 2, wherein polyphenylene ether fiber is used as a precursor.

7. A method for producing activated carbon fibers according to claim 1, wherein the raw material polyphenylene ether fibers activate carbonized carbon fibers.

8. A method for producing an activated carbon fiber molded article according to claim 3, wherein a fiber molded article made from raw material polyphenylene ether fibers is used to activate a carbonized molded article.

9. The method for producing activated carbon fibers according to claim 7, wherein the degree of irregularity R of the raw material polyphenylene ether fiber, as shown in the following formula 1, is 1.10 or more and 2.00 or less. Degree of irregularity R = Circumscribed circle diameter / Inscribed circle diameter (Formula 1) (wherein the formula, the circumscribed circle diameter is the diameter of the circle circumscribed around the fiber cross-section, and the inscribed circle diameter is the diameter of the circle inscribed around the fiber cross-section.) 10. The method for producing an activated carbon fiber molded article according to claim 8, wherein the degree of irregularity R of the fiber represented by the following formula 1 of the raw material polyphenylene ether fiber is 1.10 or more and 2.00 or less. Degree of irregularity R = Circumscribed circle diameter / Inscribed circle diameter (Formula 1) (In the formula, the circumscribed circle diameter is the diameter of the circle circumscribed around the fiber cross-section, and the inscribed circle diameter is the diameter of the circle inscribed around the fiber cross-section.) 11. An organic solvent adsorption and desorption apparatus for purifying a fluid to be treated by adsorbing and removing an organic solvent from the fluid to be treated, and further desorbing the adsorbed organic solvent, comprising an adsorption tank filled with an adsorbent that adsorbs the organic solvent by contacting the fluid to be treated and desorbs the adsorbed organic solvent by contacting water vapor or heated gas, wherein the adsorbent includes the activated carbon fiber molded body described in claim 3.

12. An organic solvent recovery system comprising an organic solvent adsorption / desorption apparatus according to claim 11, and an organic solvent recovery apparatus for recovering an organic solvent by condensing the desorption fluid discharged from the organic solvent adsorption / desorption apparatus.

13. An organic solvent adsorption and desorption treatment method for purifying a fluid to be treated by adsorbing and removing an organic solvent from the fluid containing an organic solvent, and further desorbing the adsorbed organic solvent, wherein the organic solvent is adsorbed by bringing the fluid to be treated into contact with an adsorbent, and the adsorbed organic solvent is desorbed by bringing water vapor or a heated fluid into contact with the adsorbent, and the adsorbent includes the activated carbon fiber molded body described in claim 3.

14. An organic solvent recovery method comprising cleaning a fluid to be treated by adsorbing and removing the organic solvent from the fluid containing the organic solvent, further desorbing the adsorbed organic solvent, and recovering the organic solvent by condensing the discharged desorbed fluid, wherein the organic solvent is adsorbed by bringing the fluid to be treated into contact with an adsorbent, and the adsorbed organic solvent is desorbed by bringing water vapor or heated gas into contact with the adsorbent, and the adsorbent includes the activated carbon fiber molded body described in claim 3.

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