Nonwoven fabric containing polyphenylene ether fibers, molded body, flame-resistant nonwoven fabric, flame-resistant molded body, and method for producing nonwoven fabric

Abstract

The purpose of the present invention is to provide: a nonwoven fabric that contains PPE fibers and that has been provided with high flame retardancy, heat resistance, and strength; a molded body constituted by the nonwoven fabric; a flame-resistant nonwoven fabric that contains flame-resistant polyphenylene ether fibers and that has been provided with higher flame retardancy (flame resistance) and heat resistance; and a flame-resistant molded body. Another purpose of the present invention is to provide a production method that makes it possible to efficiently produce the nonwoven fabric. The present invention relates to a nonwoven fabric containing polyphenylene ether fibers, said nonwoven fabric being characterized in that a sulfur-atom-containing compound is adhered to the polyphenylene ether fibers, and the adhesion amount of sulfur atoms in the polyphenylene ether fibers to which the sulfur-atom-containing compound is adhered is 0.1-5.0 ppm with respect to the mass of the fibers.

Description

Nonwoven fabric, molded body, flame-resistant nonwoven fabric, flame-resistant molded body, and method for producing nonwoven fabric, containing polyphenylene ether fiber

[0001] The present invention relates to a nonwoven fabric, a molded article, a flame-resistant nonwoven fabric, a flame-resistant molded article, and a method for producing a nonwoven fabric, each of which contains polyphenylene ether fibers.

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

[0003] International Publication No. 2021 / 060210

[0004]

[0003] Polyphenylene ether fibers are easily charged, and therefore, when polyphenylene ether fibers are passed through a carding machine to form a web, they become charged, making it difficult to produce a web (poor carding spinning ability) and sometimes making it impossible to form a nonwoven fabric. In order to suppress charging when polyphenylene ether fibers are passed through a carding machine, treatment of the surface of the polyphenylene ether fibers with an oil has been considered. However, it has been newly discovered that, depending on the type of oil, the oxidation onset temperature of the polyphenylene ether fibers after treatment increases, and as a result, the polyphenylene ether melts after the infusible treatment, which may cause fusion between fibers and reduce the strength of the nonwoven fabric.

[0005] Furthermore, when producing a nonwoven fabric containing polyphenylene ether fibers, there have been cases where a web is formed by imparting crimps to the polyphenylene ether fibers. However, depending on the fineness and physical properties of the polyphenylene ether fibers, imparting crimps to the polyphenylene ether fibers can drastically reduce the strength, making it impossible to obtain short fibers. Furthermore, if the polyphenylene ether fibers are not crimped, the entanglement of the polyphenylene ether fibers becomes insufficient, making it impossible to form a web.

[0006] Therefore, an object of the present invention is to provide a nonwoven fabric containing PPE fibers that can suppress fusion after infusibility treatment and that have been imparted with high levels of flame retardancy, heat resistance, and strength, a molded product made from the nonwoven fabric, and a flame-resistant nonwoven fabric and a flame-resistant molded product containing flame-resistant polyphenylene ether fibers that have been imparted with even higher levels of flame retardancy (flame resistance) and heat resistance. Furthermore, another object of the present invention is to provide a production method that can efficiently produce the nonwoven fabric.

[0007] As a result of intensive research, the present inventors have found that the above-mentioned problems can be solved by providing a nonwoven fabric containing polyphenylene ether fibers, attaching a sulfur atom-containing compound to the fiber surface, and adjusting the amount of sulfur atoms attached to the fibers to a specific range, thereby completing the present invention.

[0008] That is, the present invention relates to a nonwoven fabric containing polyphenylene ether fibers, wherein a sulfur atom-containing compound is attached to the polyphenylene ether fibers, and the amount of sulfur atoms attached to the polyphenylene ether fibers to which the sulfur atom-containing compound is attached is 0.1 ppm or more and 5.0 ppm or less based on the fiber mass.

[0009] The amount of attached sulfur atoms is preferably 0.1 ppm or more and 2.5 ppm or less based on the fiber mass.

[0010] The polyphenylene ether fiber having the sulfur atom-containing compound attached thereto preferably has an oxidation initiation temperature of 205° C. or lower.

[0011] The sulfur atom content of the sulfur atom-containing compound is preferably 100 ppm or more and 1000 ppm or less based on the mass of the sulfur atom-containing compound.

[0012] The polyphenylene ether fiber preferably has a fineness of 15 dtex or more and 100 dtex or less.

[0013] The polyphenylene ether fiber preferably contains a polyphenylene ether component having a rearrangement structure in which repeating units connected by a bond at the para position are connected by a bond at the ortho position.

[0014] The repeating units connected consecutively via the para-position bond are represented by the following general formula (1): (In the formula, R １ , R ２ are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, and R ３ each independently represents a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent), and the rearrangement structure is a repeating unit represented by the following general formula (2): (In the formula, R １ , R ２ are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, and R ３ are each independently a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, and R ３’ is the R ３ It is preferable that the structure is a divalent group in which one hydrogen atom has been removed from the group

[0015] The amount of rearrangements in the polyphenylene ether component having the rearrangement structure is preferably 0.5 mol % or more based on the total polyphenylene ether structural units in the polyphenylene ether component.

[0016] The strength of the nonwoven fabric is preferably 15 N / cm or more.

[0017] The present invention also relates to a molded article obtained by press-molding the nonwoven fabric, a flame-resistant nonwoven fabric obtained by flame-resistant treatment of the nonwoven fabric, and a flame-resistant molded article obtained by flame-resistant treatment of the molded article.

[0018] The present invention also relates to a method for producing the nonwoven fabric, comprising the steps of: applying a sulfur atom-containing compound to polyphenylene ether fibers to obtain polyphenylene ether fibers having the sulfur atom-containing compound attached thereto; and forming a web containing the polyphenylene ether fibers.

[0019] In the present invention, by attaching a specific amount of sulfur atoms to the surface of polyphenylene ether fibers, it is possible to prevent static charging of the polyphenylene ether fibers, improve entanglement of the polyphenylene ether fibers, form a nonwoven fabric without imparting crimp to the polyphenylene ether fibers, and prevent the oxidation onset temperature of the polyphenylene ether fibers from becoming too high, thereby preventing fusion after infusibility treatment. Furthermore, a nonwoven fabric containing polyphenylene ether fibers is endowed with high levels of flame retardancy, heat resistance, and strength, and a molded article formed from the nonwoven fabric is endowed with high levels of heat resistance and strength, and can be suitably used for heat-resistant sheets and the like, which require high levels of heat resistance.

[0020] Furthermore, the flame-resistant nonwoven fabric and flame-resistant molded article of the present invention are obtained by flame-resistant treatment of the nonwoven fabric and molded article of the present invention, and are endowed with higher flame retardancy (flame resistance) and heat resistance. Therefore, the flame-resistant nonwoven fabric and flame-resistant molded article of the present invention can be suitably used for flame-resistant sheets and the like that require higher flame retardancy.

[0021] Furthermore, the manufacturing method of the present invention can efficiently manufacture the nonwoven fabric of the present invention.

[0022] 1 is a cross-sectional view schematically illustrating one embodiment of a method for producing polyphenylene ether melt-spun fibers used in the present invention.

[0023] 1. Nonwoven Fabric The nonwoven fabric of the present invention comprises PPE fibers, a sulfur atom-containing compound adhered to the PPE fibers, and the amount of sulfur atoms adhered to the PPE fibers with the sulfur atom-containing compound adhered thereto is 0.1 ppm or more and 5.0 ppm or less based on the fiber mass.

[0024] The sulfur atom content of the PPE fiber having the sulfur atom-containing compound attached thereto (hereinafter sometimes referred to as "sulfur atom-attached PPE fiber") is 0.1 ppm or more, preferably 0.2 ppm or more, more preferably 0.3 ppm or more, even more preferably 0.4 ppm or more, and particularly preferably 0.5 ppm or more, relative to the fiber mass. The upper limit of the sulfur atom content is 5.0 ppm or less, preferably 4.0 ppm or less, more preferably 3.5 ppm or less, even more preferably 3.0 ppm or less, and particularly preferably 2.5 ppm or less, relative to the fiber mass. If the sulfur atom content in the sulfur atom-attached PPE fiber is less than 0.1 ppm, the effect of the sulfur atom content cannot be fully exerted, and the entanglement of the fibers is reduced, which may make it impossible to produce a carded web. If the sulfur atom content in the sulfur-atom-attached PPE fibers exceeds 5.0 ppm, the PPE fibers may slip and the entanglement between the fibers may decrease, making it impossible to produce a carded web, or even if a carded web can be produced, the strength of the nonwoven fabric may decrease. Furthermore, even if a web can be produced, if the sulfur atom content exceeds 5.0 ppm, the oxidation onset temperature of the PPE fibers increases, and fusion may occur after the nonwoven fabric containing the PPE fibers is subjected to a non-melting treatment. In the present invention, by setting the sulfur atom content in the PPE fibers within the above range, charging of the PPE fibers when they are passed through a carding machine can be suppressed, allowing the production of a good web, which in turn enables the formation of a nonwoven fabric. Furthermore, by preventing the oxidation onset temperature of the PPE fibers from becoming too high, fusion after the non-melting treatment can be prevented.

[0025] From the viewpoint of suppressing fusion after infusibility treatment, the oxidation initiation temperature of the sulfur atom-attached PPE fiber is preferably 205° C. or lower, more preferably 204° C. or lower. The lower limit of the oxidation initiation temperature is not particularly limited, but is preferably, for example, 180° C. or higher.

[0026] The sulfur atom-attached PPE fibers used in the present invention can form a good web by having a specific amount of sulfur atoms, so there is no need to impart crimps to the PPE fibers.

[0027] The sulfur atom-containing compound is not particularly limited as long as it contains a sulfur atom, but is preferably an oil containing a sulfur atom. Examples of such an oil include a water-insoluble oil, a water-soluble oil, and an emulsified oil, and among these, a water-soluble oil is preferred.

[0028] The oil agent containing sulfur atoms is not particularly limited as long as it contains sulfur atoms, and the form in which the sulfur atoms are contained is not particularly limited. Specifically, for example, sulfur atoms may be contained in the base oil structure of the oil agent, or a sulfur atom-containing compound such as toluenesulfonic acid may be added to the base oil of the oil agent. Examples of the base oil include fatty acid esters such as low-chain alcohol fatty acid esters and polyhydric alcohol fatty acid esters, long-chain alcohols, polyoxyethylene polyoxypropylene copolymers, mineral oils, nonionic surfactants, anionic surfactants, cationic surfactants, etc.

[0029] The sulfur content of the sulfur atom-containing compound is not particularly limited, but is preferably 100 ppm to 800 ppm, more preferably 150 ppm to 700 ppm, and even more preferably 180 ppm to 600 ppm. Use of a sulfur atom-containing compound having a sulfur atom content within the above range is preferred because it makes it easy to control the amount of sulfur atoms adhering to the PPE fiber within the range of 0.1 ppm to 5.0 ppm.

[0030] The basis weight of the nonwoven fabric of the present invention is not particularly limited and can be appropriately determined depending on the purpose for which the nonwoven fabric is used. For example, ２ It is preferable that the content is 100 g / m or more. ２ More preferably, it is 2000 g / m or more. ２ It is preferable that the weight is 1000 g / m or less. ２ More preferably, it is:

[0031] The thickness of the nonwoven fabric of the present invention is not particularly limited and can be appropriately determined depending on the purpose for which the nonwoven fabric is used, but is preferably about 0.1 mm or more, more preferably about 0.5 mm or more, and is preferably about 80 mm or less, more preferably about 50 mm or less.

[0032] The strength of the nonwoven fabric of the present invention is preferably 15 N / cm or more, more preferably 20 N / cm or more. The strength of the nonwoven fabric can be measured by the method described in the Examples.

[0033] The nonwoven fabric of the present invention may contain the PPE fibers, and may also contain other fibers. Examples of other fibers include, but are not limited to, polyethylene fibers, polypropylene fibers, polyamide fibers, polyester fibers, polycarbonate fibers, polyphenylene sulfide fibers, and polyetherimide fibers. The PPE fiber content in the nonwoven fabric of the present invention is preferably 90% by mass or more, and more preferably 95% by mass or more. The upper limit of the PPE fiber content is not particularly limited, but may be 100% by mass or less. Furthermore, the nonwoven fabric of the present invention does not contain reinforcing fibers such as carbon fibers or glass fibers.

[0034] Furthermore, the nonwoven fabric of the present invention contains the PPE fibers, and a sizing agent can be added to the nonwoven fabric. The sizing agent is not particularly limited, and examples include epoxy resins, urethane resins, polyester resins, vinyl ester resins, polyamide resins, polyether resins, acrylic resins, polyolefin resins, polyimide resins, and modified versions thereof. An appropriate sizing agent can be selected depending on the components of the PPE fibers. Two or more types of sizing agents can also be used in combination. Among these, epoxy resin-based sizing agents are preferred. The amount of sizing agent added is not particularly limited, but is preferably about 0.1 to 5% by mass.

[0035] The method for producing the nonwoven fabric of the present invention is not particularly limited, and the nonwoven fabric can be produced by any known method for producing nonwoven fabrics, but it can be produced well by the method for producing the nonwoven fabric of the present invention described below. The PPE fibers contained in the nonwoven fabric of the present invention (before the sulfur atom-containing compound is attached) will be described in detail below.

[0036] <<PPE Fiber>> The PPE fiber used in the nonwoven fabric of the present invention is not particularly limited, and may be any fiber containing a PPE component.

[0037] The PPE component is not particularly limited, and examples thereof include those commonly used in this field. Specifically, examples thereof include those represented by the following general formula (1): (In the formula, R １ , R ２ are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, R ３ and each independently represent a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent), or a copolymer containing two or more different repeating units of general formula (1), or a copolymer having a repeating unit of general formula (1) and a repeating unit other than the repeating unit of general formula (1).

[0038] R in the general formula (1) １ , R ２ Examples of the alkyl group include a hydrogen atom, an alkyl group having from 1 to 10 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, an octyl group, or a decyl group, an aryl group having from 6 to 10 carbon atoms, such as a phenyl group, a 4-methylphenyl group, a 1-naphthyl group, or a 2-naphthyl group, and an aralkyl group having from 7 to 10 carbon atoms, such as a benzyl group, a 2-phenylethyl group, or a 1-phenylethyl group.

[0039] When the hydrocarbon group has a substituent, examples of the substituent include a halogen atom such as a fluorine atom, an alkoxy group such as a methoxy group, etc. Specific examples of the hydrocarbon group having a substituent include a trifluoromethyl group, etc.

[0040] Among these, R １ , R ２ is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

[0041] R in the general formula (1) ３ Examples of the alkyl group include alkyl groups having from 1 to 10 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, an octyl group, and a decyl group; aryl groups having from 6 to 10 carbon atoms, such as a phenyl group, a 4-methylphenyl group, a 1-naphthyl group, and a 2-naphthyl group; and aralkyl groups having from 7 to 10 carbon atoms, such as a benzyl group, a 2-phenylethyl group, and a 1-phenylethyl group.

[0042] When the hydrocarbon group has a substituent, examples of the substituent include a halogen atom such as a fluorine atom, and an alkoxy group such as a methoxy group. Specific examples of the hydrocarbon group having a substituent include a trifluoromethyl group.

[0043] Among these, R ３ As the alkyl group, a methyl group is preferred.

[0044] Specific examples of the repeating unit of general formula (1) include repeating units derived from 2,6-dimethyl-1,4-phenylene ether, 2,6-diethyl-1,4-phenylene ether, 2-methyl-6-ethyl-1,4-phenylene ether, and 2,6-dipropyl-1,4-phenylene ether. Among these, the repeating unit derived from 2,6-dimethyl-1,4-phenylene ether is preferred.

[0045] Furthermore, the PPE may contain repeating units other than those of general formula (1) as long as the effects of the present invention are not impaired. The content of such repeating units other than those of general formula (1) is not particularly limited as long as the effects of the present invention are not impaired, but for example, it is preferably about 5 mol % or less in the copolymer, and more preferably no repeating units are contained.

[0046] The molecular weight of the PPE is not particularly limited, but the weight-average molecular weight (Mw) is preferably 40,000 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 distribution (Mw / Mn) is preferably 3.5 to 8.0, and more preferably 4.0 to 6.0.

[0047] PPE generally has a high melt viscosity, and melt spinning has been considered difficult when the PPE content is high or when it is used alone. Therefore, when melt spinning PPE, it is preferable to use a method of using a PPE containing a PPE component having a rearrangement structure in which repeating units connected by ortho bonds are connected by para bonds, or a method of mixing a PPE component having a high glass transition temperature with a PPE component having a low glass transition temperature. These methods can reduce the melt viscosity of the PPE, making it possible to melt the PPE and form melt-spun fibers.

[0048] <PPE having a rearrangement structure> Examples of the repeating units connected by a bond at the para position include the repeating unit represented by the general formula (1) above, and examples of the rearrangement structure include the repeating unit represented by the following general formula (2): (In the formula, R １ , R ２ are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, R ３ are each independently a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, and R ３’ is the R ３(representing a divalent group in which one hydrogen atom has been removed from the group consisting of the following:) The presence of such a rearrangement structure improves the fluidity of the compound to an extent that melt molding is possible, and the compound can be formed into a melt-spun fiber.

[0049] R in the general formula (2) １ ~R ３ Examples of the phenylene ether unit include those similar to those in the general formula (1). The "~" in the general formula (2) indicates that the structure following it is not particularly limited. The "~" portion may be formed from consecutive phenylene ether units linked via para-bonds, and may also contain portions partially linked at the ortho position.

[0050] The R ３’ is the R ３ represents a divalent group in which one hydrogen atom has been removed from the group, and is preferably a methylene group.

[0051] The PPE component having the rearrangement structure is preferably a homopolymer having a repeating unit of the general formula (1), a copolymer containing two or more different repeating units of the general formula (1), or a copolymer containing a repeating unit of the general formula (1) and a repeating unit other than the general formula (1), which has a rearrangement structure represented by the general formula (2).

[0052] The amount of rearrangements in the PPE component having the rearrangement structure is not particularly limited, but is preferably 0.5 mol% or more, more preferably 0.6 mol% or more, even more preferably 0.65 mol% or more, and particularly preferably 0.7 mol% or more, relative to the total PPE structural units in the PPE component. The upper limit of the amount of rearrangements is not particularly limited, but is preferably 20 mol% or less, more preferably 18 mol% or less, even more preferably 5 mol% or less, and particularly preferably 4 mol% or less. If the amount of rearrangements in the PPE component having the rearrangement structure is less than 0.5 mol%, the oxidation onset temperature of the PPE fiber tends to be high, which may cause fusion after infusibility treatment of a nonwoven fabric containing the PPE fiber, which is undesirable. In the present invention, by setting the amount of rearrangements in the PPE fiber within the above range, the fluidity is improved to a level that allows melt molding, allowing the PPE fiber to be produced as a melt-spun fiber. Furthermore, the oxidation onset temperature of the PPE fiber can be controlled within an appropriate range, thereby suppressing fusion after infusibility treatment, which is preferable. The amount of rearrangements can be measured by the method described in the Examples.

[0053] The method for forming the PPE component having the rearrangement structure and the method for lowering the melt viscosity by mixing PPEs having high and low Tg will be described later.

[0054] <Components other than PPE component> In the PPE fiber used in the present invention, the PPE content of all components forming the fiber is preferably 95 mass % or more, more preferably 98 mass % or more, and even more preferably consists essentially of PPE (100 mass %). When the PPE content in the PPE fiber is within the above range, the obtained fiber not only has excellent mechanical strength, but also excellent heat resistance, chemical resistance, flame retardancy, etc., and is therefore preferred.

[0055] Examples of resin components other than the PPE component that can be contained in the PPE fibers include styrene, polyethylene, polypropylene, polyamides such as polyamide 4, polyamide 6, polyamide 10, polyamide 11, polyamide 66, polyamide 6T, and polyamide 6T / 11, polyesters such as polyethylene terephthalate and polybutylene terephthalate, and polycarbonates, etc. However, the content thereof is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably zero (0% by mass).

[0056] Furthermore, additives such as lubricants, plasticizers, antioxidants, ultraviolet absorbers, dulling agents, and antistatic agents may also be added to the PPE fibers as long as they do not impair the effects of the present invention.

[0057] <Method for producing PPE fiber> PPE fiber can be produced by various production methods such as melt spinning, dry spinning, wet spinning, etc. Among these, melt spinning is preferred because it can achieve high productivity.

[0058] An example of the production of PPE melt-spun fibers will be described with reference to Figure 1. The raw material PPE is fed from a hopper 1 shown in Figure 1 into an extruder 2 equipped with a cylinder and a screw. The molten PPE is then metered at a discharge rate using a gear pump 3, passed through a filter medium 4 made of fine sand, and discharged from a spinning nozzle 5 to obtain melt-spun fibers. It is also preferable to install a filter 6 made of a metal nonwoven fabric or the like on the filter medium 4. Installing the filter 6 is preferable because it allows foreign matter to be removed in advance and prevents clogging of the filter medium 4.

[0059] It is also preferable to provide a heat-retaining space 7 directly below the spinning nozzle 5 and introduce an inert gas such as nitrogen into this space 8 from the viewpoint of preventing nozzle clogging due to oxidative crosslinking, and it is more preferable to introduce an inert gas heated by a heating torch 9. The temperature of the heated inert gas is preferably 100°C or higher and 500°C or lower, and more preferably 200°C or higher and 400°C or lower.

[0060] The spinning speed is not particularly limited and can be set appropriately depending on the desired fineness, etc., but in order to stably obtain fibers, it is preferably about 100 m / min or more, more preferably about 200 m / min or more, and is preferably about 5000 m / min or less, more preferably about 3000 m / min or less.

[0061] The single-hole output 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 output 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.

[0062] Examples of the PPE raw material include a homopolymer having a repeating unit of the general formula (1), a copolymer containing two or more different repeating units of the general formula (1), and a copolymer having a repeating unit of the general formula (1) and a repeating unit other than the general formula (1). The content of the repeating unit other than the general formula (1) in the copolymer can be as described above. Among these, a homopolymer having a repeating unit of the general formula (1) is preferred.

[0063] Specific examples of the homopolymer having the repeating unit of general formula (1) include poly(2,6-dimethyl-1,4-phenylene ether), poly(2,6-diethyl-1,4-phenylene ether), poly(2-methyl-6-ethyl-1,4-phenylene ether), and poly(2,6-dipropyl-1,4-phenylene ether). Among these, poly(2,6-dimethyl-1,4-phenylene ether) is preferred.

[0064] As the poly(2,6-dimethyl-1,4-phenylene ether), commercially available products can also be suitably used. Specific examples include PPO640, PPO646, and PPOSA120 manufactured by SABIC Innovative Plastics, and ZYLON S201A and ZYLON S202A manufactured by Asahi Kasei Chemicals Corporation.

[0065] Furthermore, as mentioned above, when melting PPE, it is possible to lower the melt viscosity by mixing PPE having a high Tg and PPE having a low Tg.

[0066] The glass transition temperature of the PPE component having a high glass transition temperature is preferably 170° C. or higher, more preferably 200° C. or higher, and even more preferably 210° C. or higher. There is no particular upper limit to the glass transition temperature, but it is preferably 230° C. or lower. Having the glass transition temperature of the raw material PPE within this range is preferred because it allows the production of PPE fibers with high heat resistance.

[0067] The glass transition temperature of the PPE component having a low glass transition temperature is preferably less than 170° C. By adding a PPE having a glass transition temperature of less than 170° C., the melt viscosity is reduced and the flowability is improved.

[0068] The content of the PPE having a glass transition temperature of 170°C or higher is preferably 70% by mass or higher, more preferably 80% by mass or higher, and even more preferably 90% by mass or higher, in the raw PPE component. The upper limit of the content of PPE having a glass transition temperature of 170°C or higher is not particularly limited, but is preferably 100% by mass or lower. In the present invention, it is preferred to include PPE having a high glass transition temperature (i.e., a high molecular weight) in the above range, since the resulting PPE molten fiber will have excellent mechanical strength, heat resistance, chemical resistance, flame retardancy, etc.

[0069] In addition, resin components and additives other than the PPE component may be contained in addition to the raw material PPE. The resin components and additives other than the PPE component are as described above. Furthermore, the content of resin components other than the PPE component in the raw material is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably 0% by mass or less.

[0070] The extruder equipped with a cylinder and a screw may be a single-screw extruder or a twin-screw extruder that is commonly used in this field, but in the present invention, it is preferable to use a twin-screw extruder.

[0071] The screw peripheral speed is not particularly limited and can be within the range commonly used in this field. However, when forming fibers using PPE having a rearrangement structure, the screw peripheral speed must be such that the rearrangement reaction of the raw material PPE occurs, and is 3.6 m / min or more, preferably 3.7 m / min or more, and more preferably 3.8 m / min or more. The upper limit of the screw peripheral speed is not particularly limited, but is preferably 94.2 m / min or less. In the present invention, by increasing the screw rotation speed to a screw peripheral speed of 3.6 m / min or more, high shear force can be applied to the raw material PPE in the cylinder, resulting in scission of the molecular chains of the PPE and the formation of PPE having a rearrangement structure. The formation of PPE having the rearrangement structure makes melt spinning of PPE possible.

[0072] If the temperature inside the cylinder is too low, the fluidity of the resin will be poor, and if it is too high, the fluidity will be improved but foaming will occur due to thermal decomposition of the resin, so it is necessary to select a processing temperature that strikes a balance between these two. The temperature inside the cylinder is, for example, preferably 250°C or higher and 350°C or lower, and more preferably 280°C or higher and 330°C or lower.

[0073] The PPE fibers used in the present invention may be short fibers, which can be obtained, for example, by doubling the PPE fibers to form a tow and cutting the resulting fiber.

[0074] The glass transition temperature of the PPE fiber used in the present invention is preferably 170°C or higher, more preferably 175°C or higher, and even more preferably 180°C or higher. Having a glass transition temperature within this range can impart very high heat resistance. There is no particular upper limit, but from the viewpoint of moldability, it is preferably 300°C or lower, and more preferably 250°C or lower.

[0075] The fineness of the PPE fiber is not particularly limited and can be determined appropriately depending on the purpose for which the fiber is used, but is preferably 15 dtex or more and 100 dtex or less, and more preferably 22 dtex or more and 60 dtex or less.

[0076] The fiber length of the PPE fiber is not particularly limited and can be adjusted appropriately depending on the application, but is usually 1 mm or more and 200 mm or less, preferably 2 mm or more and 180 mm or less, and more preferably 3 mm or more and 150 mm or less.

[0077] 2. Method for producing nonwoven fabric The method for producing a nonwoven fabric containing PPE fibers of the present invention is characterized by comprising the steps of: applying a sulfur atom-containing compound to PPE fibers to obtain PPE fibers having the sulfur atom-containing compound attached thereto; and forming a web containing the PPE fibers.

[0078] The sulfur atom attachment amount of the sulfur-containing compound and the PPE fiber is as described above.

[0079] The method for applying the sulfur atom-containing compound is not particularly limited, and includes methods commonly used in this field. Specifically, the sulfur atom-containing compound can be applied to PPE melt-spun fibers using a gear pump. In this case, the sulfur atom-containing compound can be dissolved in a solvent such as water, and the resulting solution can be applied. The discharge rate is not particularly limited, and may be any discharge rate that can achieve the desired sulfur atom attachment amount. For example, a rate of about 1 g / min to 20 g / min is preferred, and a rate of about 2 g / min to 15 g / min is more preferred.

[0080] The amount of sulfur atom-containing compound to be applied is not particularly limited, and can be determined so that the amount of sulfur atoms adhering to the PPE fiber falls within a specific range. For example, the amount is preferably 0.05% by mass or more and 1.0% by mass or less, and more preferably 0.05% by mass or more and 0.8% by mass or less, relative to the mass of the PPE fiber.

[0081] Methods for forming a web made of PPE fibers include conventionally known methods, and a web can be formed by a carding method using a carding machine.

[0082] The resulting web can be subjected to a web fiber bonding process such as needle punching, spunlace, thermal bonding, or chemical bonding.

[0083] 3. Molded Article and Manufacturing Method Thereof The molded article of the present invention is obtained by press-molding the nonwoven fabric of the present invention and contains PPE.

[0084] The PPE contained in the molded body may be any PPE that contains the above-mentioned PPE component.

[0085] The shape of the molded body is not particularly limited and can be appropriately determined depending on the purpose for which the molded body is used, and can be molded into, for example, a membrane (including a film or a film-like substance) or a plate, or can be formed into a required shape using a mold. The thickness of the molded body is not particularly limited and can be appropriately determined depending on the purpose for which the molded body is used, and is, for example, preferably about 0.01 mm or more and 100 mm or less, and more preferably about 0.05 mm or more and 80 mm or less.

[0086] The content of PPE in the molded article of the present invention is preferably 5% by mass or more, more preferably 10% by mass or more, based on the total amount of the molded article, and is preferably 100% by mass or less, based on the total amount of the molded article.

[0087] The molded article of the present invention contains PPE, but may also contain other components. The content of the other components is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 0% by mass, based on the total amount of the molded article. Examples of the other components include the same components that can be contained in the nonwoven fabric described above.

[0088] The method for producing the molded body of the present invention is not particularly limited, and the molded body can be produced by any known method for producing a molded body, but can be produced well by the method for producing the molded body of the present invention described below.

[0089] The method for producing a molded article of the present invention is characterized by including a step of pressing the nonwoven fabric obtained by the method for producing a nonwoven fabric of the present invention.

[0090] Examples of the nonwoven fabric obtained by the method for producing a nonwoven fabric of the present invention include those mentioned above.

[0091] The press working temperature is not particularly limited, but is preferably 260° C. or higher, more preferably 280° C. or higher. The upper limit is not particularly limited, but is preferably 420° C. or lower, more preferably 400° C. or lower.

[0092] The pressing pressure is not particularly limited, but is preferably 0.1 MPa or more, more preferably 0.5 MPa or more, and is preferably 50 MPa or less, more preferably 40 MPa or less.

[0093] The press working time is not particularly limited, but is preferably 0.5 seconds or more, more preferably 10 seconds or more, and even more preferably 30 seconds or more. It is also preferably 1200 seconds or less, and more preferably 600 seconds or less. Setting the press working time within this range is preferable because it can suppress thermal degradation.

[0094] The pressing can be carried out by a method commonly used in the art.

[0095] 4. Flame-resistant nonwoven fabric and its manufacturing method The flame-resistant nonwoven fabric containing the flame-resistant PPE fiber of the present invention is obtained by subjecting a nonwoven fabric containing the PPE fiber of the present invention to a flame-resistant treatment (two-stage heat treatment (infusible treatment, flame-resistant treatment)), and has very high levels of flame retardancy, heat resistance, etc.

[0096] The method for producing a flame-resistant nonwoven fabric containing the flame-resistant PPE fiber of the present invention is characterized by comprising: a step of heat-treating the nonwoven fabric of the present invention in air at 120°C or higher and 240°C or lower for 1 hour or longer and 30 hours or shorter to make it infusible; and a step of heat-treating the infusible nonwoven fabric in air at 260°C or higher and 400°C or lower for 0.1 hour or longer and 10 hours or shorter to make it flame-resistant.

[0097] The PPE fibers and the nonwoven fabric containing the PPE fibers are as described above.

[0098] In the infusible treatment, a nonwoven fabric containing PPE fibers is heat-treated in air at 120°C or higher and 240°C or lower for 1 hour or higher and 30 hours or lower. Here, "in air" refers to an environment that is not particularly controlled. The treatment temperature is 120°C or higher, preferably 140°C or higher, and more preferably 160°C or higher. The treatment temperature is 240°C or lower, preferably 230°C or lower, and more preferably 220°C or lower. The treatment time is 1 hour or higher, preferably 1.5 hours or higher, and more preferably 2 hours or higher. The treatment time is 30 hours or lower, preferably 25 hours or lower, and more preferably 23 hours or lower. In the present invention, by using the nonwoven fabric of the present invention, an appropriate flame-retardant treatment can be performed without melting the infusible PPE fibers.

[0099] After the infusibility treatment, a flame-resistant treatment is performed in air at 260°C or higher and 400°C or lower for 0.1 to 10 hours. "In air" refers to an environment that is not particularly controlled. The treatment temperature is 260°C or higher, preferably 270°C or higher, and more preferably 280°C or higher. The treatment temperature is 400°C or lower, preferably 380°C or lower, and more preferably 360°C or lower. The treatment time is 0.1 hours or higher, preferably 0.3 hours or higher, and more preferably 0.5 hours or higher. The treatment time is 10 hours or shorter, preferably 8 hours or shorter, and more preferably 6 hours or shorter. By using the treatment time and temperature described above, a flame-resistant nonwoven fabric exhibiting extremely high flame retardancy (flame resistance), heat resistance, etc. can be formed. In the manufacturing method of the present invention, the nonwoven fabric of the present invention is subjected to an infusible treatment and a flame-retardant treatment, which makes it possible to prevent the PPE fibers from melting and fusing together during the flame-retardant treatment after the infusible treatment. Alternatively, a nonwoven fabric can be formed using PPE fibers that have been infusible and flame-retardant treated in advance. The infusible and flame-retardant treatment of the PPE fibers can be performed by the same methods as those used for the infusible and flame-retardant treatment of the nonwoven fabric.

[0100] 5. Flame-resistant molded body and its manufacturing method The flame-resistant molded body of the present invention is obtained by molding a nonwoven fabric containing the PPE fiber of the present invention into a molded body and then subjecting the molded body to a flame-resistant treatment (two-stage heat treatment (infusibility treatment and flame-resistant treatment)), and has very high flame retardancy, heat resistance, etc.

[0101] The method for producing a flame-resistant molded body containing a flame-resistant PPE of the present invention is characterized by comprising: a step of heat-treating the molded body of the present invention in air at 120°C or higher and 240°C or lower for 1 hour or longer and 30 hours or shorter to make it infusible; and a step of heat-treating the infusible molded body in air at 260°C or higher and 400°C or lower for 0.1 hour or longer and 10 hours or shorter to make it flame-resistant.

[0102] The nonwoven fabric, molded body, pressing conditions for the molded body, etc. are as described above. The infusible step and flame-resistant step may be the same as those for the flame-resistant nonwoven fabric.

[0103] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The physical properties and other properties in the following examples were evaluated using the following methods.

[0104] (1) Fineness Five randomly selected locations on the sample were used to measure the single fiber diameter (n = 20) using an optical microscope, and the overall average value (D) was calculated. Fibers were taken from the same five locations, and the specific gravity of the fibers (n = 5) was measured using a density gradient tube to calculate the overall average value (p). Next, the fineness (dtex), which is the fiber weight per 10,000 m, was calculated from the single fiber cross-sectional area and average specific gravity calculated from the average single fiber diameter.

[0105] (2) Glass Transition Temperature (Tg) Using a differential scanning calorimeter (model: DSC-Q100) manufactured by TA Instruments Inc., 2 mg of fiber was measured in a nitrogen atmosphere from 30°C to 250°C at a heating rate of 10°C / min, and the temperature at the intersection of an extension of the baseline below the glass transition temperature and a tangent line showing the maximum slope at the transition portion was taken as the glass transition temperature (Tg).

[0106] (3) Amount of sulfur atoms attached to sulfur-atom-attached PPE fiber ４The concentration was measured and converted into S concentration. Automatic sample combustion device: AQF-2100H manufactured by Mitsubishi Chemical Analytech Co., Ltd. Absorbent: 3% hydrogen peroxide solution Combustion furnace inlet temperature: 1000°C (outlet: 1100°C) Ar: 200 ml / min O ２ Flow rate: 400 ml / min Ion chromatograph: DIONEX ICS-1600, manufactured by DIONEX Column: IonPac AS12A (4 mm x 200 mm) Guard column: IonPac AG12A (4 mm x 50 mm) Eluent: 2.7 mmol / L Na ２ CO ３ / 0.3mmol / L NaHCO ３ Flow rate: 1.5 mL / min Column heater temperature: 35°C Suppressor: AERS500 4 mm (applied current 22 mA)

[0107] (4) Basis Weight: Measured in accordance with JIS L1906 (2000) 5.2 Mass per unit area.

[0108] (5) Oxidation initiation temperature of sulfur atom-attached PPE fiber Using a TG-DTA (TGDTA7200, manufactured by Hitachi High-Technologies Corporation), a sample (10 mg) was placed in an aluminum pan and heated from 50°C to 450°C at a rate of 1°C / min in an air atmosphere (air flow rate: 200 mL / min). The moving average (n = 30) of the obtained DTG (μg / °C) was plotted against the temperature, and the temperature at which DTG = -2 was defined as the oxidation initiation temperature.

[0109] (6) Carding Spinnability A web was produced through a carding machine, and the state of the web was confirmed. ◯: The fibers were entangled, and the web could be conveyed. △: The fibers were poorly entangled, and the web broke partially when conveyed. ×: The fibers were poorly entangled, and the web broke completely when conveyed.

[0110] (7) Nonwoven Fabric Strength: According to the provisions of JIS L 1913 (1998) 6.3, a 2.5 cm wide sample was measured with a chuck distance of 5 cm and a pulling speed of 10 cm / min.

[0111] (8) Evaluation of the Presence or Absence of Fusion After Infusibilization Samples after infusibilization treatment (treated in an air atmosphere at 200°C for 16 hours) were bent to check for cracking. ◯: No fusion between fibers, no cracking when bent. △: The fibers were fused together, and partial cracking occurred when bent. ×: The fibers were fused together, and complete cracking occurred when bent.

[0112] (9) Amount of dislocation structure in PPE fiber Resonance frequency 600 MHz １ The measurement was carried out by H-NMR measurement. The measurement device used was a BRUKER NMR device (device name: AVANCE-NEO600), and the measurement was carried out as follows. 10 mg of the PPE fibers obtained in the examples and comparative examples were dissolved in deuterated chloroform, and the solution was filled into an NMR tube within 2 hours and the measurement was carried out. Deuterated chloroform was used as the lock solvent, the waiting time was 1 second, the data acquisition time was 4 seconds, and the number of accumulations was 64. Deuterated benzene may also be used as the solvent. The analysis of the amount of rearrangement structure was carried out as follows. The R at the 3rd and 5th positions of PPE was １ , R ２ The peaks due to the protons of the R group and the R ３’ The peak integral values ​​of the peaks derived from the protons of the divalent group (e.g., methylene group) represented by the formula: A and B, respectively, and the amount of rearranged structure was calculated by the following formula: Amount of rearranged structure (mol %)=(B / (A+B))×100

[0113] Example 1 Poly(2,6-dimethyl-1,4-phenylene ether) (PPO (registered trademark) 640, glass transition temperature (Tg): 221°C, manufactured by SABIC Innovative Plastics) was extruded using a twin-screw extruder (product name: KZW15TW-30MG) manufactured by Technovel Co., Ltd. The twin-screw extruder had four cylinder zones, and from the hopper side, the cylinders were numbered 1, 2, 3, and 4, with cylinders 1 to 3 set to 290°C, and cylinder 4 and the cylinder head set to 310°C. The screw rotation speed was set to 700 rpm, and the screw peripheral speed was set to 33.0 m / min.

[0114] A gear pump was installed downstream of the extruder, and the polymer was extruded through a metal nonwoven filter (product name: NF-07, manufactured by Nippon Seisen Co., Ltd.) into a nozzle (nozzle hole diameter: 0.80 mm, nozzle hole land length: 4.0 mm, number of nozzle holes: 48) (total output rate: 50 g / min). The polymer extruded from the nozzle was wound up at a spinning speed of 473 m / min. During winding, a gear pump with a capacity of 0.06 cc / rev was used to apply an aqueous dispersion of sulfur atom-containing oil (sulfur atom content: 540 ppm) diluted to 1.5% by mass with water as the solvent (output rate: 6.7 g / min, oil application amount: 0.20% by mass relative to the PPE fiber mass). The sulfur atom attachment amount was 1.1 ppm relative to the fiber mass. The obtained fiber had a rearrangement structure (amount of rearrangement structure: 0.8 mol% relative to all PPE units).

[0115] PPE staples with an average fiber length of 89 mm were carded into a web using a commercially available carding machine, and the fibers were then entangled using a needle punch method to form a nonwoven fabric. The resulting nonwoven fabric had a thickness of 4.5 mm and a basis weight of 435 g / m. ２ The nonwoven fabric thus obtained was evaluated. The evaluation results are shown in Table 1.

[0116] Example 2 PPE fibers were obtained in the same manner as in Example 1, except that the total output rate was 33 g / min, the spinning speed was 313 m / min, the output rate of the sulfur-containing oil solution was 3.0 g / min, and the amount of oil solution applied was changed to 0.09 mass% relative to the mass of the PPE fibers. The amount of attached sulfur atoms was 0.5 ppm relative to the mass of the fibers, and the obtained fibers had rearranged structures (amount of rearranged structures: 1.2 mol% relative to all PPE units).

[0117] A nonwoven fabric was formed in the same manner as in Example 1, except that the obtained fibers were used. The thickness of the obtained nonwoven fabric was 5.1 mm and the basis weight was 515 g / m ２ The nonwoven fabric thus obtained was evaluated. The evaluation results are shown in Table 1.

[0118] Example 3: PPE fiber was produced in the same manner as in Example 1, except that the nozzle used was changed (nozzle hole diameter: 0.50 mm, nozzle hole land length: 1.0 mm, number of nozzle holes: 24), the total output rate was 13 g / min, the spinning speed was 246 m / min, the output rate of sulfur-containing oil solution was 3.5 g / min, and the oil solution application amount was changed to 0.4 mass% based on the PPE fiber mass. The sulfur atom attachment amount was 2.2 ppm based on the fiber mass, and the obtained fiber had a rearranged structure (amount of rearranged structures: 2.4 mol% based on all PPE units).

[0119] A nonwoven fabric was formed in the same manner as in Example 1, except that the obtained fibers were used. The thickness of the obtained nonwoven fabric was 4.6 mm and the basis weight was 421 g / m ２ The nonwoven fabric thus obtained was evaluated. The evaluation results are shown in Table 1.

[0120] Example 4 PPE fibers were obtained in the same manner as in Example 1, except that the sulfur-containing oil solution was changed to one containing 190 ppm sulfur atoms, the discharge rate of the sulfur-containing oil solution was changed to 14.6 g / min, and the amount of oil solution applied was changed to 0.44 mass% relative to the mass of the PPE fibers. The amount of attached sulfur atoms was 0.8 ppm relative to the mass of the fibers, and the obtained fibers had rearranged structures (amount of rearranged structures: 0.8 mol% relative to all PPE units).

[0121] A nonwoven fabric was formed in the same manner as in Example 1, except that the obtained fibers were used. The thickness of the obtained nonwoven fabric was 5.5 mm and the basis weight was 627 g / m ２ The nonwoven fabric thus obtained was evaluated. The evaluation results are shown in Table 1.

[0122] Examples 5 to 8 PPE fibers were obtained in the same manner as in Example 2, except that the discharge rate of the sulfur-containing oil in Example 2 was changed to 2.9 g / min (Example 5), 5.0 g / min (Example 6), 13.4 g / min (Example 7), and 24.5 g / min (Example 8), and the oil application rates were changed to 0.15 mass%, 0.20 mass%, 0.40 mass%, and 0.70 mass%, respectively, relative to the PPE fiber mass. The sulfur atom attachment amounts were 0.8 ppm, 1.1 ppm, 2.2 ppm, and 3.8 ppm, respectively, relative to the fiber mass, and the obtained fibers had rearrangement structures (rearrangement structure amount: 1.2 mol% relative to all PPE units).

[0123] Except for using the obtained fibers, a nonwoven fabric was formed in the same manner as in Example 2. The obtained nonwoven fabric was evaluated. The evaluation results are shown in Table 1.

[0124] Comparative Example 1 PPE fibers were obtained in the same manner as in Example 3, except that the sulfur-containing oil was changed to one containing 3,800 ppm sulfur atoms. The amount of attached sulfur atoms was 15.2 ppm relative to the fiber mass, and the obtained fibers had rearrangement structures (amount of rearrangement structures: 2.4 mol% relative to all PPE units).

[0125] An attempt was made to form a nonwoven fabric in the same manner as in Example 1 except that the obtained fibers were used, but the carding spinning properties were poor and it was not possible to form a web or a nonwoven fabric.

[0126] Comparative Example 2 PPE fibers were obtained in the same manner as in Example 1, except that the concentration of the sulfur atom-containing oil aqueous dispersion was changed to 9.0 mass% and the amount of oil applied was changed to 1.2 mass% relative to the mass of the PPE fibers. The amount of attached sulfur atoms was 6.5 ppm relative to the mass of the fibers, and the obtained fibers had rearrangement structures (amount of rearrangement structures: 0.8 mol% relative to all PPE units).

[0127] A nonwoven fabric was formed in the same manner as in Example 1, except that the obtained fibers were used. The thickness of the obtained nonwoven fabric was 4.9 mm and the basis weight was 502 g / m ２The nonwoven fabric thus obtained was evaluated. The evaluation results are shown in Table 1.

[0128] Comparative Example 3 PPE fibers were obtained in the same manner as in Example 1, except that the temperatures of cylinders 1 to 3 were changed to 280° C. and the temperature of cylinder 4 was changed to 300° C. The amount of attached sulfur atoms was 6.5 ppm based on the fiber mass, and the obtained fibers had rearrangement structures (amount of rearrangement structures: 0.4 mol% based on the total PPE units).

[0129] A nonwoven fabric was formed in the same manner as in Example 1, except that the obtained fibers were used. The thickness of the obtained nonwoven fabric was 5.9 mm and the basis weight was 703 g / m ２ The nonwoven fabric thus obtained was evaluated. The evaluation results are shown in Table 1.

[0130] Comparative Example 4 PPE fibers were obtained in the same manner as in Example 2, except that no sulfur-containing oil was applied. The amount of sulfur atoms attached to the obtained PPE fibers was 0 ppm relative to the fiber mass, and the obtained fibers had rearrangement structures (amount of rearrangement structures: 1.2 mol% relative to all PPE units).

[0131] An attempt was made to form a nonwoven fabric in the same manner as in Example 1 except that the obtained fibers were used, but the carding spinning properties were poor and it was not possible to form a web or a nonwoven fabric.

[0132] Comparative Example 5 PPE fibers were obtained in the same manner as in Example 2, except that the concentration of the sulfur atom-containing oil aqueous dispersion was changed to 15.0 mass % and the amount of oil applied was changed to 1.01 mass % relative to the mass of the PPE fibers. The amount of attached sulfur atoms was 5.5 ppm relative to the mass of the fibers, and the obtained fibers had rearrangement structures (amount of rearrangement structures: 1.2 mol % relative to all PPE units).

[0133] Except for using the obtained fibers, a nonwoven fabric was formed in the same manner as in Example 2. The obtained nonwoven fabric was evaluated. The evaluation results are shown in Table 1.

[0134]

[0135] As is clear from Table 1, the nonwoven fabrics of Examples 1 to 8 of the present invention had good carding properties, high nonwoven fabric strength, and suppressed fusion after infusibility treatment compared to the comparative examples.

[0136] On the other hand, in Comparative Example 1, an oil agent with a high sulfur content was used, resulting in a large amount of sulfur atoms adhering to the fibers, which increased the slipperiness between the fibers and worsened fiber entanglement, resulting in poor carding spinning properties and failure to form a nonwoven fabric. In Comparative Examples 2, 3, and 5, a large amount of oil agent was used, resulting in a large amount of sulfur atoms adhering to the fibers, but nonwoven fabrics were able to be formed. However, because the amount of sulfur atoms was high, the oxidation onset temperature was high, resulting in fusion when the nonwoven fabric was infusible. In Comparative Example 4, no oil agent was used, resulting in poor electrostatic chargeability and failure to form a nonwoven fabric.

[0137] 1 Hopper 2 Extruder 3 Gear pump 4 Filter medium 5 Spinning nozzle 6 Filter 7 Heat-retaining space 8 Introduction of inert gas 9 Heating torch

Claims

1. A nonwoven fabric comprising polyphenylene ether fibers, the polyphenylene ether fibers having a sulfur atom-containing compound attached thereto, and the amount of sulfur atoms attached to the polyphenylene ether fibers having the sulfur atom-containing compound attached thereto being 0.1 ppm or more and 5.0 ppm or less based on the fiber mass.

2. The nonwoven fabric according to claim 1, characterized in that the amount of sulfur atoms attached is 0.1 ppm or more and 2.5 ppm or less based on the fiber mass.

3. The nonwoven fabric according to claim 1, characterized in that the oxidation onset temperature of the polyphenylene ether fibers to which the sulfur atom-containing compound is attached is 205°C or lower.

4. The nonwoven fabric according to claim 1, characterized in that the sulfur atom content of the sulfur atom-containing compound is 100 ppm or more and 800 ppm or less based on the mass of the sulfur atom-containing compound.

5. The nonwoven fabric according to claim 1, wherein the fineness of the polyphenylene ether fibers is 15 dtex or more and 100 dtex or less.

6. The nonwoven fabric according to claim 1, wherein the polyphenylene ether fiber contains a polyphenylene ether component having a rearrangement structure in which a bond at the ortho position is connected to a repeating unit connected successively with a bond at the para position.

7. The repeating units connected consecutively at the para position are represented by the following general formula (1): (In the formula, R １ , R ２ are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent; R ３ each independently represents a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, and the rearrangement structure is a repeating unit represented by the following general formula (2): (In the formula, R １ , R ２ are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent; R ３ each independently represents a hydrocarbon group having 1 to 10 carbon atoms which may have a substituent, R ３’ is the R ３ The nonwoven fabric according to claim 6, characterized in that the structure is represented by the following formula (III):

8. The nonwoven fabric according to claim 6, characterized in that the amount of rearrangements in the polyphenylene ether component having the rearrangement structure is 0.5 mol % or more based on the total polyphenylene ether structural units in the polyphenylene ether component.

9. The nonwoven fabric according to claim 1, characterized in that the strength of the nonwoven fabric is 15 N / cm or more.

10. A molded product obtained by press molding the nonwoven fabric according to any one of claims 1 to 9.

11. A flame-retardant nonwoven fabric obtained by subjecting the nonwoven fabric according to any one of claims 1 to 9 to a flame-retardant treatment.

12. A flame-resistant molded product obtained by subjecting the molded product according to claim 10 to a flame-resistant treatment.

13. A method for producing a nonwoven fabric according to any one of claims 1 to 9, comprising the steps of: applying a sulfur atom-containing compound to polyphenylene ether fibers to obtain polyphenylene ether fibers having the sulfur atom-containing compound attached thereto; and forming a web containing the polyphenylene ether fibers.