Polyphenylene ether fiber, nonwoven fabric, and method for producing polyphenylene ether fiber

Abstract

The purpose of the present invention is to provide: PPE fibers in which fusion between the fibers does not occur even when the fibers are repeatedly used in a high-temperature environment; a nonwoven fabric; and a method for producing the PPE fibers. The present invention relates to a polyphenylene ether fiber containing a polyphenylene ether component, wherein a modification ratio R represented by Formula 1 below is 1.11 or more and 2.00 or less.　Modification ratio R=diameter of circumscribed circle / diameter of inscribed circle (Formula 1) (In Formula 1, the diameter of the circumscribed circle is the diameter of a circle circumscribed about a cross section of the fiber, and the diameter of the inscribed circle is the diameter of a circle inscribed in the cross section of the fiber.)

Description

Polyphenylene ether fibers, nonwoven fabrics, and methods for producing polyphenylene ether fibers

[0001] The present invention relates to polyphenylene ether fibers, nonwoven fabrics, and methods for producing polyphenylene ether fibers.

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

[0003] Furthermore, while various fibers with irregular cross-sections are known, PPE fibers with irregular cross-sections were previously unknown.

[0004] International Publication No. 2021 / 060210

[0005] Due to its rigid aromatic main chain structure, PPE has a high melt viscosity. When spun using a spinning nozzle with an irregular cross-sectional shape, localized high-shear regions tend to form at the intersections of the irregular cross-sections, resulting in uneven shear rates. In these high-shear regions, localized temperature increases promote gelation of the PPE, raising concerns about the formation of so-called eye discharge. As a result, it is difficult to obtain irregularly shaped PPE fibers stably over the long term. From this perspective, it is presumed that irregularly shaped PPE fibers have not been formed conventionally.

[0006] Applications of heat-resistant PPE fibers include, for example, batting in insulating materials for heat retention and heat-resistant felt for heat shielding. Although PPE fibers have excellent heat resistance and flame retardancy, repeated exposure to heat can cause them to partially melt and fuse together, resulting in a loss of flexibility in the nonwoven fabric containing the PPE fibers.

[0007] Therefore, the object of the present invention is to provide PPE fibers that do not fuse together even when repeatedly used in a high-temperature environment, a nonwoven fabric made from said fibers, and a method for producing PPE fibers.

[0008] As a result of diligent research, the inventors of the present invention have found that by keeping the degree of irregularity of the fiber cross-section within a certain range, it is possible to suppress fusion due to repeated use while suppressing the deterioration of fiber properties, thereby solving the above problem and completing the present invention. The degree of irregularity referred to here is the value obtained by dividing the diameter of the circle circumscribing the fiber cross-section by the diameter of the circle inscribed in the fiber cross-section.

[0009] The present invention relates to a PPE fiber containing a PPE component, wherein the degree of deformation R, as shown in the following formula 1, is 1.11 or more and 2.00 or less. Degree of deformation 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.)

[0010] When the outer circumference of the cross-section of the PPE fiber is T1, and the outer circumference of a round cross-section fiber having the same fiber cross-sectional area as the PPE fiber is T2, it is preferable that the outer circumference ratio (T1 / T2) is 1.05 or more and 1.40 or less.

[0011] It is preferable that the PPE component has a dislocation structure in which it is connected by ortho bonds within a repeating unit consisting of consecutive para bonds.

[0012] The repeating unit formed by the aforementioned para-position bonding is given by the following general formula (1): (In the formula, R １ , R ２ Each is independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may have substituents, and R ３ Each of these is a repeating unit represented by (which independently represents a hydrocarbon group having 1 to 10 carbon atoms, which may have substituents), and the rearrangement structure is represented by the following general formula (2): (In the formula, R １ , R ２ Each is independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may have substituents, and R ３ Each is independently a hydrocarbon group having 1 to 10 carbon atoms, which may have substituents, and R ３ ' is the aforementioned R ３ It is preferable that the structure be represented by (representing a divalent group from which one hydrogen atom has been removed).

[0013] It is preferable that the amount of dislocations in the PPE component having the dislocation structure is 0.05 mol% or more relative to the total PPE structural units in the PPE component.

[0014] Preferably, the content of the PPE component is 95% by mass or more of the total components forming the fiber.

[0015] It is preferable that the single filament fineness of the PPE fiber is 1.0 dtex or more and 100 dtex or less.

[0016] Furthermore, the present invention relates to a nonwoven fabric containing the aforementioned PPE fibers.

[0017] Furthermore, the present invention relates to a method for producing PPE fibers, comprising the steps of melting and extruding PPE, which is a raw material, using an extruder equipped with a cylinder and a screw, and discharging the molten PPE from a spinning nozzle and spinning it.

[0018] It is preferable that the degree of irregularity R' of the nozzle hole of the spinning nozzle, as shown in the following formula 1', is 1.15 or greater. 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 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.)

[0019] This invention aims to reduce the contact area between fibers in the entire nonwoven fabric structure by increasing the degree of irregularity of the PPE fiber cross-section. By reducing the contact area between fibers, even if fusion occurs, the contact points become easier to detach, and as a result, flexibility is maintained. On the other hand, if the degree of irregularity is increased too much, the uneven parts become easily crushed, and as a result, the contact area cannot be reduced, the contact points become difficult to detach when fusion occurs, and flexibility is lost. Therefore, in this invention, by using PPE fibers with a specific degree of irregularity, the flexibility of the nonwoven fabric containing these PPE fibers is excellent.

[0020] This is a schematic cross-sectional view showing one embodiment of the method for producing PPE fibers of the present invention. This is a schematic cross-sectional view showing one embodiment of the cross-section of PPE fibers of the present invention. This is a schematic cross-sectional view showing the cross-section of PPE fibers of the present invention and the cross-section of a round cross-section fiber having the same area as the PPE fibers. This is a schematic cross-sectional view showing one embodiment of a spinning nozzle used in the present invention.

[0021] 1. PPE Fibers The PPE fibers of the present invention contain a PPE component and have a deformation degree R of 1.11 or more and 2.00 or less, as shown in the following formula 1. Deformation degree 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.)

[0022] A deformation degree R of 1.00 corresponds to a perfect circle, and a larger deformation degree R means that the cross-section of the fiber is more deformed. As shown in Figure 2, the cross-section 11 of the PPE fiber is photographed in two dimensions, and from the image, the diameter of the perfect circle circumscribing the fiber cross-section (circumscribed circle 12 in Figure 2) is taken as the circumscribed circle diameter, and furthermore, the diameter of the perfect circle inscribed in 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.

[0023] The PPE fibers of the present invention have a degree of irregularity of 1.11 or higher, preferably 1.13 or higher, and more preferably 1.15 or higher. A degree of irregularity of 1.11 or higher reduces the contact area between fibers in the entire nonwoven fabric when the PPE fibers are used to make a nonwoven fabric. As a result, even if fusion occurs, the contact points are less likely to separate, and the flexibility of the nonwoven fabric is maintained. The degree of irregularity R is 2.00 or lower, preferably 1.90 or lower, and more preferably 1.80 or lower. If the degree of irregularity R is too high, the uneven parts are more likely to be crushed, and as a result, the contact area cannot be reduced, the contact points are less likely to separate when fusion occurs, and the flexibility of the nonwoven fabric is lost.

[0024] The cross-sectional shape of the PPE fiber of the present invention is not particularly limited as long as the above-mentioned degree of irregularity is satisfied. For example, the cross-section may be a lobed (3 to 20 lobes) cross-section or a polygonal cross-section. The lobed cross-section refers to, for example, a shape in which four slits are radially arranged from the center of a circumscribed circle in the case of a 4-lobed shape, and a shape in which eight slits are radially arranged from the center of a circumscribed circle in the case of an 8-lobed shape. A shape in which a slits are radially arranged from the center of a circumscribed circle is also referred to as an "a-lobed cross-section". Figure 2 shows a 5-lobed cross-section. In the present invention, a 3 or more lobed cross-section is preferable from the viewpoint of the flexibility of the obtained PPE nonwoven fabric, and a 4 or more lobed cross-section is more preferable.

[0025] As shown in Figure 3, when T1 is the perimeter of the cross-section of the PPE fiber (cross-sectional area S), and T2 is the perimeter of a round cross-section fiber having the same fiber cross-sectional area S as the PPE fiber, the perimeter ratio (T1 / T2) is preferably 1.05 or more and 1.40 or less. Here, the round cross-section fiber refers to a fiber that has a round cross-section and has no cavities continuous in the length direction in the fiber cross-section.

[0026] T1 / T2 is preferably 1.05 or more, more preferably 1.07 or more, and still more preferably 1.09 or more. Further, T1 / T2 is preferably 1.40 or less, more preferably 1.35 or less, and still more preferably 1.30 or less. When T1 / T2 is within the above range, flexibility after heat treatment can be obtained, which is preferable.

[0027] The PPE fiber of the present invention may be a short fiber. The short fiber can be obtained, for example, by combining PPE fibers to form a tow and cutting the tow.

[0028] The single yarn fineness of the PPE fiber is not particularly limited, and can be appropriately determined according to the purpose for which the fiber is used. For example, it is preferably 1 dtex or more and 100 dtex or less, more preferably 1.2 dtex or more and 60 dtex or less, and still more preferably 1.5 dtex or more and 40 dtex or less.

[0029] The PPE component contained in the PPE fiber of the present invention will be described below.

[0030] <PPE COMPONENT> The PPE component is not particularly limited, and those commonly used in the art can be mentioned. Specifically, the following general formula (1): (wherein R １ , R ２ are each independently a hydrogen atom or an optionally substituted hydrocarbon group having 1 to 10 carbon atoms, and R ３ each independently represent an optionally substituted hydrocarbon group having 1 to 10 carbon atoms) homopolymers having a repeating unit represented by the formula, or copolymers containing two or more different repeating units of general formula (1), and copolymers having the repeating unit of general formula (1) and a repeating unit other than general formula (1) can be mentioned.

[0031] As for R １ to R ３ in the above general formula (1), examples of the hydrocarbon group having 1 to 10 carbon atoms include alkyl groups having 1 to 10 carbon atoms such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, pentyl group, cyclopentyl group, hexyl group, cyclohexyl group, octyl group and decyl group; aryl groups having 6 to 10 carbon atoms such as phenyl group, 4-methylphenyl group, 1-naphthyl group and 2-naphthyl group; aralkyl groups having 7 to 10 carbon atoms such as benzyl group, 2-phenylethyl group and 1-phenylethyl group.

[0032] When the hydrocarbon group has a substituent, examples of the substituent include halogen atoms such as fluorine atom, and alkoxy groups such as methoxy group. Specific examples of the substituted hydrocarbon group include trifluoromethyl group and the like.

[0033] Among these, for R １ and R ２ , a hydrogen atom and a methyl group are preferable, a hydrogen atom is more preferable, and for R ３ , a methyl group is preferable.

[0034] 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.

[0035] 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.

[0036] 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 (representing a divalent group from which one hydrogen atom has been removed).

[0037] 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.

[0038] 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.

[0039] 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).

[0040] 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, and enables the formation of melt-spun fibers having irregular cross-sections.

[0041] 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).

[0042] The weight-average absolute molecular weight (Mw) of the PPE component is preferably 10,000 g / mol or more, more preferably 20,000 g / mol or more, even more preferably 30,000 g / mol or more, and particularly preferably 35,000 g / mol or more. Furthermore, the weight-average absolute molecular weight (Mw) is preferably 150,000 g / mol or less, more preferably 100,000 g / mol or less, and even more preferably 80,000 g / mol or less. Setting the weight-average absolute molecular weight (Mw) within the above range is preferable from the viewpoint of heat resistance. Here, weight-average absolute molecular weight (Mw) refers to the true weight-average molecular weight of the polymer. The weight-average molecular weight measured by conventional gel permeation chromatography (GPC) is a relative weight-average molecular weight obtained using linear polystyrene or the like with a known molecular weight as a standard polymer, and in cases where branched structures exist in the polymer, it may not be possible to accurately evaluate the molecular weight. The weight-average absolute molecular weight (Mw) is measured using a GPC instrument equipped with a predetermined column and a multi-angle light scattering detector, allowing for accurate molecular weight measurement without being affected by polymer structures such as branched structures. The weight-average absolute molecular weight (Mw) can be measured by the method described in the examples below. This weight-average absolute molecular weight (Mw) is different from the weight-average (relative) molecular weight obtained by the conventional GPC method using polystyrene equivalent values ​​(relative values).

[0043] The number-average absolute molecular weight (Mn) of the PPE component is preferably 8,000 g / mol or more, more preferably 9,000 g / mol or more, and even more preferably 10,000 g / mol or more. Furthermore, the number-average absolute molecular weight (Mn) is preferably 100,000 g / mol or less, more preferably 80,000 g / mol or less, and even more preferably 70,000 g / mol or less. Setting the number-average absolute molecular weight (Mn) within the above range is preferable from the viewpoint of heat resistance. Here, the number-average absolute molecular weight (Mn) is the true number-average molecular weight of the polymer, and, like the weight-average absolute molecular weight (Mw), is measured by a GPC device equipped with a predetermined column and a multi-angle light scattering detector. This number-average absolute molecular weight (Mn) is different from the number-average (relative) molecular weight obtained by the polystyrene equivalent value (relative value) obtained by the conventional GPC method.

[0044] The absolute molecular weight dispersion (weight-average absolute molecular weight (Mw) / number-average absolute molecular weight (Mn)) of the PPE component is preferably 5.0 or less, more preferably 4.5 or less, and even more preferably 4.0 or less. Mw / Mn is 1 or greater. A larger Mw / Mn tends to broaden the glass transition peak. Therefore, from a quality standpoint, it is preferable to keep it within the above range.

[0045] The relative molecular weight of the PPE component is not particularly limited, but the weight-average relative molecular weight (Mw') is preferably 40,000 to 100,000, and more preferably 50,000 to 80,000. The number-average relative molecular weight (Mn') is preferably 7,000 to 30,000, and more preferably 8,000 to 20,000. The relative molecular weight dispersion (Mw' / Mn') is preferably 2.5 to 9.0, and more preferably 2.8 to 8.0.

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

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

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

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

[0050] 2. Method for producing PPE fibers The method for producing PPE fibers according to the present invention is characterized by including the steps of melting and extruding raw material PPE using an extruder equipped with a cylinder and a screw, and spinning the molten PPE by extruding it from a spinning nozzle.

[0051] An example of manufacturing PPE melt-spun fibers will be explained using Figure 1. The raw material, PPE, is fed from the hopper 1 in Figure 1 into an extruder 2 equipped with a cylinder and 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.)

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] As the poly(2,6-dimethyl-1,4-phenylene ether) mentioned above, commercially available products can also be suitably used. Specifically, examples include PPO640, PPO646, and PPOSA120 manufactured by SABIC Innovative Plastic, and Xylon S201A and Xylon S202A manufactured by Asahi Kasei Chemicals Corporation.

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

[0064] The glass transition temperature of the PPE component having a high glass transition temperature is preferably 170°C or higher, more preferably 200°C or higher, and even more preferably 210°C or higher. 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.

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

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

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

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

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

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

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

[0072] 3. PPE Nonwoven Fabric The present invention relates to a PPE nonwoven fabric formed from the PPE fibers.

[0073] The method for manufacturing PPE nonwoven fabric is not particularly limited, and methods commonly used in this field can be appropriately adopted. Examples of nonwoven fabric manufacturing methods include the spunbond method, meltblown method, spunlace method, needle punch method, thermal bond method, and chemical bond method.

[0074] Because the PPE nonwoven fabric of the present invention uses the PPE fibers of the present invention, fusion between fibers can be suppressed even when repeatedly used in high-temperature environments, and as a result, the nonwoven fabric has excellent flexibility.

[0075] The PPE nonwoven fabric of the present invention can be used in applications requiring heat resistance and flexibility, and can be suitably used, for example, as padding in insulating materials for heat retention, heat-resistant felt for heat shielding, sputter sheets, etc.

[0076] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to 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%.

[0077] (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.

[0078] (2) Maximum point stress and maximum point elongation were measured in accordance with JIS L-1013 8.5.1. The stress at the maximum load was defined as the maximum point stress, and the elongation rate at the maximum load was defined as the maximum point elongation.

[0079] (3) 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).

[0080] (4) The amount of dislocation structure in PPE fibers at a resonance frequency of 600 MHz １ The measurement was performed using 1H-NMR. A BRUKER NMR spectrometer (model name: AVANCE-NEO600) was used, and the measurement was performed as follows: 10 mg of PPE fiber obtained in the examples and comparative examples was dissolved in deuterated chloroform, and the solution was packed into an NMR tube within 2 hours for measurement. Deuterated chloroform was used as the locking solvent, with a waiting time of 1 second, a data acquisition time of 4 seconds, and 64 integration cycles. Deuterated benzene may also be used as the solvent. The rearrangement structure amount was analyzed as follows: R at the 3 and 5 positions of PPE. １ , R ２Peaks 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

[0081] (5) Molecular weight measurement (5-1) Absolute molecular weight The number-average molecular weight (Mn), weight-average molecular weight (Mw), and molecular weight dispersion (Mw / Mn) of the absolute molecular weight were all determined using gel permeation chromatography (GPC). The measurement conditions were as follows. Apparatus: OMNISEC RESOLVE (manufactured by Spectris Co., Ltd.) Detector: OMNISEC REVEAL (differential refractive index detector, light scattering detector, viscosity detector, manufactured by Spectris Co., Ltd.) Column: TSKgel SuperHM-H manufactured by Tosoh Corporation (two columns connected in series) Solvent: Chloroform Temperature: 40°C Flow rate: 0.6 mL / min Sample concentration: 1.0 mg / mL Injection volume: 20 μL (5-2) Relative molecular weight The number average molecular weight (Mn'), weight average molecular weight (Mw'), and molecular weight dispersion (Mw' / Mn') of the relative molecular weight in polystyrene equivalent were measured under the same conditions as in "(5-1) Absolute molecular weight" above, and a differential refractive index detector was used. The standard polystyrene used to create the calibration curve is as follows. Standard samples: Monodisperse polystyrene "waters Polystyrene Standard (peak MW = 2698)" "Shodex STANDARD SM-105 (S-3.37, S-13.9, S-30.3, S-52.4, S-205, S-696, S-1110, S-2210, S-3740)" Samples were prepared by dissolving 5 mg of PPE fiber obtained in the examples and comparative examples in 5 mL of chloroform.

[0082] (6) 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)

[0083] (7) Degree of Deformation R The degree of deformation R of PPE fibers was determined by observing microscope images using a scanning electron microscope (product name: SU1510, manufactured by Hitachi High-Technologies Corporation). From these microscope images, the diameters of the circumscribed circle and the inscribed circle were read at more than 50 locations on the cross-section of the fiber, and the degree of deformation R (diameter of circumscribed circle / diameter of inscribed circle) was calculated. The average value of the obtained values ​​was taken as the degree of deformation R.

[0084] (8) Perimeter length and cross-sectional area of ​​the cross-section The cross-sectional area and perimeter length of the cross-section of the PPE 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. Image processing software ImageJ was used for image analysis.

[0085] (9) Fibre fusion rate after heat treatment A multifilament of PPE fiber (number of filaments: 48) was suspended in a dryer at 200°C, left for 30 minutes, and then removed and cooled to room temperature. The yarn was then floated in water to separate it, and the number of strands was counted. The fusion rate was then calculated using the following formula: Fibre fusion rate (%) = (original filament count - number of yarns after heat treatment) / (original filament count - 1) × 100

[0086] (10) Flexibility of the nonwoven fabric after heat treatment The obtained nonwoven fabric was heat-treated three times in air at 200°C for 30 minutes each time. After that, it was wrapped around a cylinder with a diameter of 50 mmφ and evaluated according to the following evaluation criteria. ○: No cracks or splits occurred. ×: Cracks or splits occurred.

[0087] (11) Basis weight Measured in accordance with JIS L1906 (2000) 5.2 Mass per unit area.

[0088] 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.

[0089] Downstream of the extruder, a gear pump was installed, and the polymer was extruded through a metal nonwoven fabric filter (product name: NF-10, manufactured by Nippon Seisen Co., Ltd.) into a nozzle (circumscribed diameter of nozzle hole: 1.40 mm, inscribed diameter of 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 volume: 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.

[0090] 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 needle was processed on both sides with a needle depth of 2 mm (front) and 7 mm (back), resulting in a base weight of 406 g / m². ２ We obtained a PPE nonwoven fabric.

[0091] Example 2 In forming the PPE fibers, the nozzle shape was changed to one in which eight slits were 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 these PPE fibers, a PPE nonwoven fabric was obtained in the same manner as in Example 1.

[0092] Example 3: PPE fibers were obtained in the same manner as in Example 1, except that the slit width was changed by 0.3 mm. Using these PPE fibers, a PPE nonwoven fabric was obtained in the same manner as in Example 1.

[0093] Example 4 In forming the PPE fibers, the nozzle shape was changed to one in which eight slits were 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 these PPE fibers, a PPE nonwoven fabric was obtained in the same manner as in Example 1.

[0094] Example 5 PPE fibers were obtained in the same manner as in Example 3, except that the raw material for forming the PPE fibers was changed to poly(2,6-dimethyl-1,4-phenylene ether) (IUPIACE PX100F, glass transition temperature (Tg): 214°C, manufactured by Global Polyacetal Co., Ltd.). Using these PPE fibers, a PPE nonwoven fabric was obtained in the same manner as in Example 3.

[0095] Comparative Example 1: PPE fibers were obtained in the same manner as in Example 1, except that the nozzle for forming the PPE fibers was changed to a circular (round cross-section) nozzle with a diameter of 1.40 mm. A PPE nonwoven fabric was obtained using these PPE fibers in the same manner as in Example 1.

[0096] Comparative Example 2: In forming the PPE fibers, the nozzle shape was changed to one in which eight slits were arranged radially from the center of the circumscribed circle, and the slit width was changed by 0.2 mm. Except for these changes, PPE fibers were obtained in the same manner as in Example 1. Using these PPE fibers, a PPE nonwoven fabric was obtained in the same manner as in Example 1.

[0097] Comparative Example 3: PPE fibers were obtained in the same manner as in Example 1, except that the slit width was changed by 0.25 mm. Using these PPE fibers, a PPE nonwoven fabric was obtained in the same manner as in Example 1.

[0098]

[0099] In Examples 1 to 5, the PPE fibers did not fuse together even after heat treatment, and the nonwoven fabric did not fuse even after repeated exposure to heat, demonstrating excellent flexibility. In Comparative Examples 1 and 2, fusion occurred in all PPE fibers after heat treatment. Furthermore, cracks occurred in the nonwoven fabric made from these PPE fibers. In Comparative Example 3, although fusion did not occur after heat treatment, cracks occurred in the nonwoven fabric made from these PPE fibers.

[0100] 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 PPE fiber 12. Circumscribed circle 13. Inscribed circle 14. Slit width

Claims

1. A polyphenylene ether fiber containing a polyphenylene ether component, wherein the degree of deformation R, as shown in the following formula 1, is 1.11 or greater and 2.00 or less. Degree of deformation 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.) 2. The polyphenylene ether fiber according to claim 1, wherein when the outer circumference length of the cross-section of the polyphenylene ether fiber is T1 and the outer circumference length of a round cross-section fiber having the same fiber cross-sectional area as the polyphenylene ether fiber is T2, the outer circumference length ratio (T1 / T2) is 1.05 or more and 1.40 or less.

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

4. The repeating unit formed by the para-position bond is given by the following general formula (1): (In the formula, R １ , R ２ Each is independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may have substituents, and R ３ Each of these is a repeating unit represented by (which independently represents a hydrocarbon group having 1 to 10 carbon atoms, which may have substituents), and the rearrangement structure is represented by the following general formula (2): (In the formula, R １ , R ２ Each is independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may have substituents, and R ３ Each is independently a hydrocarbon group having 1 to 10 carbon atoms, which may have substituents, and R ３ ' is the aforementioned R ３ The polyphenylene ether fiber according to claim 3, having a structure represented by (representing a divalent group from which one hydrogen atom has been removed).

5. The polyphenylene ether fiber according to claim 3, wherein the amount of dislocation in the polyphenylene ether component having the dislocation structure is 0.05 mol% or more relative to the total polyphenylene ether structural units in the polyphenylene ether component.

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

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

8. A nonwoven fabric containing polyphenylene ether fibers according to any one of claims 1 to 7.

9. A method for producing polyphenylene ether fibers according to any one of claims 1 to 7, comprising the steps of: melting and extruding polyphenylene ether, which is a raw material, using an extruder equipped with a cylinder and a screw; and discharging the molten polyphenylene ether from a spinning nozzle and spinning it.

10. The method for producing polyphenylene ether fibers according to claim 9, wherein the degree of deformation R' of the nozzle hole of the spinning nozzle, as shown in the following formula 1', is 1.15 or greater. Degree of irregularity R' = Circumscribed circle diameter / Inscribed circle diameter (Equation 1') (In this equation, the circumscribed circle diameter is the diameter of the circle circumscribed around the nozzle hole cross-section, and the inscribed circle diameter is the diameter of the circle inscribed around the nozzle hole cross-section.)

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