Crimped polyphenylene ether fiber, nonwoven fabric, molded article, flameproofed nonwoven fabric, flameproofed molded article, and method for producing crimped polyphenylene ether fiber and nonwoven fabric

Abstract

The purpose of the present invention is to provide: crimped polyphenylene ether fiber having high fire retardancy and heat resistance as well as having good strength and elongation; nonwoven fabric comprising said crimped polyphenylene ether fiber; a molded article formed from said nonwoven fabric; and flameproofed nonwoven fabric and flameproofed molded article comprising flameproofed polyphenylene ether fiber provided with higher fire retardancy (flame resistance) and heat resistance. Another purpose of the present invention is to provide a production method whereby the crimped polyphenylene ether fiber and nonwoven fabric can be efficiently produced. The present invention pertains to crimped polyphenylene ether fiber having a fineness of 20 dtex or more, and a crimp number of 2.5 crimps / 25 mm or more, the crimped polyphenylene ether fiber being characterized in that the crimped polyphenylene ether fiber has a strength, represented by the following formula, of 15 cN / dtex•%1 / 2 to 50 cN / dtex•%1 / 2.

Description

Crimped polyphenylene ether fiber, nonwoven fabric, molded body, flame-resistant nonwoven fabric, flame-resistant molded body, and method for producing crimped polyphenylene ether fiber and nonwoven fabric

[0001] The present invention relates to crimped polyphenylene ether fibers, nonwoven fabrics containing crimped polyphenylene ether, molded articles, flame-resistant nonwoven fabrics, flame-resistant molded articles, and methods for producing crimped polyphenylene ether fibers and nonwoven fabrics.

[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]

[0005] When polyphenylene ether fibers having a large fineness are used to produce a nonwoven fabric, the polyphenylene ether fibers may be insufficiently entangled, making it impossible to form a web. Furthermore, in order to improve the entanglement of the fibers, a web may be formed by crimping the polyphenylene ether fibers. However, it has been newly discovered that defects such as cracks may occur in the fibers during crimping, resulting in reduced strength and elongation of the crimped fibers and nonwoven fabrics formed using the fibers.

[0005] Therefore, an object of the present invention is to provide crimped polyphenylene ether fibers having high flame retardancy and heat resistance as well as good strength and elongation, nonwoven fabrics containing the crimped polyphenylene ether fibers, molded articles made from the nonwoven fabrics, and flame-resistant nonwoven fabrics and flame-resistant molded articles containing flame-resistant polyphenylene ether fibers to which higher flame retardancy (flame resistance) and heat resistance have been imparted.Furthermore, another object of the present invention is to provide methods for efficiently producing the crimped polyphenylene ether fibers and nonwoven fabrics.

[0006] As a result of extensive research, the present inventors have found that crimped polyphenylene ether fibers having a specific rib can solve the above problems, and have thus completed the present invention.

[0007] That is, the present invention provides a crimped polyphenylene ether fiber having a fineness of 20 dtex or more and a number of crimps of 2.5 / 25 mm or more, wherein the crimped polyphenylene ether fiber has a crimp strength of 15 cN / dtex·% as expressed by the following formula: １／２ More than 50cN / dtex・% １／２ The present invention relates to a crimped polyphenylene ether fiber characterized by the following:

[0008] The crimped polyphenylene ether fibers preferably have a strength of 0.9 cN / dtex or more.

[0009] The crimped polyphenylene ether fiber preferably has an elongation of 110% or more.

[0010] The crimping strength of the polyphenylene ether fiber before crimping is 15 cN / dtex·% as expressed by the following formula: １／２ It is preferable that this is equal to or greater than this.

[0011] The strength retention, expressed by the following formula, is preferably 70% or more: Strength retention (%) = (strength of fiber after crimping / strength of fiber before crimping) x 100

[0012] The elongation retention, expressed by the following formula, is preferably 50% or more: Elongation retention (%)=(elongation of fiber after crimping / elongation of fiber before crimping)×100

[0013] The present invention also relates to a nonwoven fabric comprising the crimped polyphenylene ether fiber.

[0014] The strength of the nonwoven fabric is 450 g / m ２ The weight per unit area is preferably 20 N / cm or more.

[0015] 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.

[0016] The present invention also provides the method for producing the crimped polyphenylene ether fiber, wherein the crimped polyphenylene ether fiber has a crimp strength of 15 cN / dtex·% or less, and the crimp strength is 15 cN / dtex·% or less. １／２ The present invention relates to a method for producing crimped polyphenylene ether fibers, the method comprising the step of crimping the polyphenylene ether fibers described above to obtain crimped polyphenylene ether fibers having a number of crimps of 2.5 per 25 mm or more.

[0017] The present invention also relates to a method for producing a nonwoven fabric, comprising the step of forming a web containing the crimped polyphenylene ether fibers.

[0018] In the present invention, by setting the Liqui in a specific range in a crimped polyphenylene ether fiber having a specific number of crimps, it is possible to obtain a crimped polyphenylene ether fiber having excellent strength and elongation. The crimped polyphenylene ether fiber has good entanglement with other fibers and can be used to form a nonwoven fabric. A nonwoven fabric containing the crimped polyphenylene ether fiber has high flame retardancy and heat resistance, as well as excellent strength and elongation. A molded article formed from the nonwoven fabric is endowed with high heat resistance and strength and can be suitably used for heat-resistant sheets and the like that require high heat resistance.

[0019] 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.

[0020] Furthermore, the production method of the present invention can efficiently produce the crimped polyphenylene ether fibers and nonwoven fabric of the present invention.

[0021] 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.

[0022] 1. Crimped Polyphenylene Ether Fibers The crimped PPE fibers of the present invention have a fineness of 20 dtex or more, a number of crimps of 2.5 / 25 mm or more, and a crimping coefficient of 15 cN / dtex·% as expressed by the following formula: １／２ More than 50cN / dtex・% １／２ The present invention is characterized by the following:

[0023] The fineness of the crimped PPE fiber is 20 dtex or more, and may be 22 dtex or more, or may be 30 dtex or more. In the present invention, even if the PPE fiber has a large fineness, defects such as cracks do not occur in the PPE fiber during crimping, and the obtained crimped PPE fiber has excellent strength and elongation, and as a result, the strength and elongation of a nonwoven fabric containing the crimped PPE fiber are also excellent.

[0024] The crimped PPE fiber of the present invention has a crimp strength of 15 cN / dtex. １／２ More than 50cN / dtex・% １／２ The lower limit of the crimped PPE fiber is 16 cN / dtex·% １／２ It is preferable that the elasticity is 17 cN / dtex·% or more. １／２ The upper limit of the crimp strength of the crimped PPE fiber is 40 cN / dtex·%. １／２ Preferably, it is 35 cN / dtex·% or less. １／２ By setting the viscosity of the crimped PPE fiber within the above range, the crimped PPE fiber has excellent strength and elongation, and as a result, the nonwoven fabric containing the crimped PPE fiber has excellent strength and elongation.

[0025] The crimp number of the crimped PPE fibers is 2.5 / 25 mm or more. If the crimp number is less than 2.5 / 25 mm, the PPE fibers may be poorly entangled, making it impossible to form a web and making it difficult to form a nonwoven fabric. If the crimp number is less than 2.5 / 25 mm, even if a nonwoven fabric can be formed, the strength of the nonwoven fabric may be low. The crimp number is preferably 3 / 25 mm or more, and more preferably 4 / 25 mm or more. The crimp number is preferably 15 / 25 mm or less, and more preferably 10 / 25 mm or less. If the crimp number is too high, the polyphenylene ether fibers may be too strongly entangled, resulting in poor passability through a carding machine and making it difficult to form a web.

[0026] The crimped PPE fibers preferably have a strength of 0.9 cN / dtex or more, more preferably 1.0 cN / dtex or more. There is no particular upper limit to the strength of the crimped PPE fibers, but it is, for example, about 10 cN / dtex or less.

[0027] The elongation of the crimped PPE fiber is preferably 110% or more, more preferably 115% or more. There is no particular upper limit to the elongation of the crimped PPE fiber, but it is, for example, about 300% or less.

[0028] The crimped PPE fiber of the present invention is formed by crimping PPE fiber. The crimped PPE fiber has a crimp strength of 15 cN / dtex·% or less, as expressed by the above formula. １／２ It is preferable that the elasticity is 16 cN / dtex·% or more. １／２ More preferably, it is 17 cN / dtex·% or more. １／２ More preferably, it is 18 cN / dtex·% or more. １／２ The upper limit of the crimp strength of the PPE fiber before crimping is not particularly limited, but it is, for example, 50 cN / dtex·% １／２ It is preferable that the density is about 40 cN / dtex·% or less. １／２ It is more preferable that the fiber density is about 35 cN / dtex·% or less. １／２By setting the tension of the PPE fiber before crimping within the above range, it is possible to prevent defects such as cracks from occurring in the fiber during crimping, and as a result, it is possible to set the tension of the PPE fiber after crimping to 15 cN / dtex·% or less. １／２ More than 50cN / dtex・% １／２ This is preferable because it is possible to control the temperature to the following value, thereby obtaining crimped PPE fibers with excellent strength and elongation.

[0029] It is preferable that the crimped PPE fiber has the same strength as the PPE fiber before crimping (i.e., it is preferable that the strength of the fiber does not decrease due to the crimping process). Therefore, the strength retention of the crimped PPE fiber, as expressed by the following formula, is preferably 70% or more, and more preferably 75% or more. The preferred upper limit of the strength retention is 100%. Strength retention (%) = (strength of fiber after crimping / strength of fiber before crimping) x 100

[0030] Furthermore, it is preferable that the crimped PPE fiber of the present invention has an elongation comparable to that of the PPE fiber before crimping (i.e., it is preferable that the elongation of the fiber does not decrease due to the crimping process). Therefore, the elongation retention of the crimped PPE fiber, as expressed by the following formula, is preferably 50% or more, more preferably 52% or more, and even more preferably 55% or more. The preferred upper limit of the elongation retention is 100%. Elongation retention (%) = (elongation of fiber after crimping / elongation of fiber before crimping) x 100

[0031] The method for producing the crimped PPE fiber of the present invention is not particularly limited, and the fiber can be produced by any known fiber production method, but the crimped PPE fiber of the present invention can be produced satisfactorily by the method for producing the crimped PPE fiber described below. The pre-crimped PPE fiber used in the present invention will be described in detail below.

[0032] <<PPE Fiber>> The PPE fiber (before being crimped) used in the present invention is not particularly limited, and may be any fiber containing a PPE component.

[0033] 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).

[0034] 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.

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

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

[0037] R in the general formula (1) ３Examples 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.

[0038] 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.

[0039] Among these, R ３ As the alkyl group, a methyl group is preferred.

[0040] 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.

[0041] 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.

[0042] 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 dispersity (Mw / Mn) is preferably 3.5 to 8.0, and more preferably 4.0 to 6.0.

[0043] PPE generally has a high melt viscosity, and melt spinning has been considered difficult when the PPE content is high or when the PPE is used alone. Therefore, when melt spinning PPE, it is preferable to use a method using a PPE containing a PPE component with a rearrangement structure, 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.

[0044] <PPE Having Rearrangement Structure> Examples of the PPE having a rearrangement structure include PPEs 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 It is preferable to use a PPE containing a PPE component having a rearrangement structure represented by the formula (a divalent group in which one hydrogen atom has been removed from the group (III)). The presence of such a rearrangement structure improves the fluidity to an extent that melt molding is possible, and melt-spun fibers can be formed.

[0045] R in the general formula (2) １ ~R ３Examples 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.

[0046] 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.

[0047] 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).

[0048] 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. In the present invention, by setting the amount of rearrangements in the PPE fiber within the above range, the fluidity is improved to a degree that allows melt molding, and melt-spun fibers can be obtained, which is preferable. The amount of rearrangements can be measured by the method described in the examples.

[0049] 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.

[0050] <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.

[0051] 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).

[0052] 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.

[0053] <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.

[0054] 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 hopper 1 in Figure 1 into extruder 2 equipped with a cylinder and screw. The molten PPE passes through piping 10, where the discharge rate is metered by gear pump 3. The melted PPE then passes through piping 11, passes through filter medium 4 made of fine sand, and is discharged from spinning nozzle 5, thereby obtaining melt-spun fibers. It is also preferable to install a filter 6 made of a metal nonwoven fabric or the like on top of 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.

[0055] 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.

[0056] The spinning speed is not particularly limited and can be set appropriately depending on the required fineness, etc., but is preferably about 100 m / min or more, more preferably about 300 m / min or more, and is preferably about 5000 m / min or less, more preferably about 3000 m / min or less.

[0057] The single-hole output rate of the spinning nozzle 5 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.

[0058] The total discharge rate of the spinning nozzle 5 is preferably 20 g / min or more, more preferably 30 g / min or more. The upper limit of the discharge rate is not particularly limited, but is preferably 150 g / min or less, more preferably 120 g / min or less.

[0059] The residence time in the extruder 2 equipped with a cylinder and a screw is preferably less than 1.5 minutes, more preferably 1.0 minute or less, and even more preferably 0.6 minute or less, from the viewpoint of suppressing a decrease in the raw yarn strength of the PPE fiber before crimping. The lower limit of the residence time is not particularly limited as long as it is a time that allows the raw materials to melt, but is, for example, about 0.1 minute or more.

[0060] 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.

[0061] 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 formation of PPE having a rearrangement structure. The formation of PPE having the rearrangement structure enables melt spinning of PPE.

[0062] 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.

[0063] If the temperature of the pipes 10 and 11 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 pipe temperature is, for example, preferably 250°C or higher and 350°C or lower, and more preferably 280°C or higher and 340°C or lower.

[0064] The temperature of the spinning nozzle 5 is not particularly limited, but from the viewpoint of ease of deformation during spinning, it is preferably, for example, 300°C or higher and 380°C or lower, and more preferably 335°C or higher and 360°C or lower.

[0065] In the present invention, as described above, the crimp strength of the PPE fiber before crimping is 15 cN / dtex·%. １／２ The above is preferable, and PPE fibers having such a force can be obtained by appropriately adjusting the screw peripheral speed, discharge rate, temperature inside the cylinder, spinning nozzle temperature, etc.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] The fineness of the PPE fibers before crimping is approximately the same as that of the PPE fibers after crimping (that is, the fineness of the PPE fibers before and after crimping does not change).

[0077] 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 5 mm or more and 150 mm or less.

[0078] 2. Method for producing crimped PPE fiber The method for producing crimped PPE fiber of the present invention is to produce a crimped PPE fiber having a crimping strength of 15 cN / dtex·% as expressed by the following formula: １／２ The method is characterized by including a step of crimping the PPE fibers described above to obtain crimped PPE fibers having a number of crimps of 2.5 per 25 mm or more.

[0079] Riki is 15cN / dtex・% １／２ The above-mentioned pre-crimped PPE fibers, the manufacturing method thereof, and the number of crimps are as described above.

[0080] The method of imparting crimps is not particularly limited as long as it is a method that can process the yarn so that the number of crimps is 2.5 / 25 mm or more. Examples of such methods include false twisting, push-in processing, gear processing, and composite crimping processing. Of these, push-in processing is preferred from the viewpoint of productivity.

[0081] The method may further include a step of applying an oil to the PPE fibers before subjecting the PPE fibers to crimping. The oil is not particularly limited, and any oil commonly used in spinning may be used. Spinning oils impart smoothness and antistatic properties to the fibers, and examples thereof include water-insoluble oils, water-soluble oils, and emulsified oils. Of these, water-soluble oils are preferred.

[0082] The method for applying the oil is not particularly limited, and includes methods commonly used in this field. Specifically, the spinning oil can be applied to the PPE melt-spun fibers using a gear pump. The discharge rate is not particularly limited, and may be any rate that achieves the desired amount of oil applied. For example, a rate of about 0.015 g / min to 15 g / min is preferred, and about 1.0 g / min to 10 g / min is more preferred. By setting the discharge rate within the above range, the amount of oil applied can be kept within an appropriate range, which prevents the PPE fibers from becoming charged when passing through a carding machine and facilitates the production of a uniform nonwoven fabric, which is preferred.

[0083] 3. Nonwoven Fabric and Manufacturing Method Thereof The nonwoven fabric of the present invention is characterized by containing the crimped polyphenylene ether fiber described above, and since it contains crimped PPE fiber having a specific number of crimps and suppressed fiber defects, the strength and elongation of the nonwoven fabric are excellent.

[0084] The nonwoven fabric of the present invention contains the PPE fibers and can be treated with a sizing agent. 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.

[0085] The amount of the sizing agent added is not particularly limited, but is preferably 0.1 to 5% by mass.

[0086] The nonwoven fabric of the present invention may contain thermoplastic fibers other than PPE as long as the effects of the present invention are not impaired. The nonwoven fabric of the present invention does not contain reinforcing fibers such as carbon fibers or glass fibers.

[0087] The strength of the nonwoven fabric is 450 g / m ２ The nonwoven fabric preferably has a basis weight of 20 N / cm or more. The nonwoven fabric preferably has an elongation of 80% or more.

[0088] Furthermore, the method for producing the nonwoven fabric of the present invention includes, but is not limited to, a step of forming a web containing the crimped PPE fibers.

[0089] The crimped PPE fibers are as described above.

[0090] Methods for forming a web made of crimped PPE fibers include conventionally known methods, such as a carding method using a carding machine.

[0091] The resulting web can be subjected to a web fiber bonding process such as needle punching, spunlace, thermal bonding, or chemical bonding.

[0092] 4. 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 polyphenylene ether.

[0093] The polyphenylene ether contained in the molded body may be any polyphenylene ether as long as it contains the above-mentioned polyphenylene ether component.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] The method for producing a molded article of the present invention is characterized by including a step of pressing the nonwoven fabric of the present invention.

[0099] Examples of the nonwoven fabric include those mentioned above.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] The pressing can be carried out by a method commonly used in the art.

[0104] 5. Flame-resistant nonwoven fabric and its manufacturing method The flame-resistant nonwoven fabric containing the flame-resistant polyphenylene ether fiber of the present invention is obtained by subjecting a nonwoven fabric containing the crimped PPE fiber of the present invention to a flame-resistant treatment (two-stage heat treatment (infusibility treatment and flame-resistant treatment)), and has very high flame retardancy, heat resistance, etc.

[0105] 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.

[0106] The crimped PPE fibers and the nonwoven fabric containing the PPE fibers are as described above.

[0107] In the infusible treatment, the 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.

[0108] After the infusibility treatment, a flame-retardant treatment is performed in air at 260°C to 400°C 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 longer, preferably 0.3 hours or longer, and more preferably 0.5 hours or longer. The treatment time is 10 hours or shorter, preferably 8 hours or shorter, and more preferably 6 hours or shorter. By using the above treatment time and temperature, a flame-retardant nonwoven fabric exhibiting extremely high flame retardancy (flame resistance), heat resistance, etc. can be formed. Nonwoven fabrics can also be formed using PPE fibers that have been previously treated for infusibility and flame retardancy. The infusible treatment and flame-resistant treatment for the PPE fiber can be carried out by the same methods as those for the infusible treatment and flame-resistant treatment for the nonwoven fabric.

[0109] 6. Flame-resistant molded body and its manufacturing method The flame-resistant molded body of the present invention is obtained by subjecting the molded body of the present invention to a flame-resistant treatment (two-stage heat treatment (infusibility treatment, flame-resistant treatment)), and has very high flame retardancy, heat resistance, etc.

[0110] 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.

[0111] The molded body is as described above. The infusible step and the flame-resistant step may be the same as those for the flame-resistant nonwoven fabric.

[0112] 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.

[0113] (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.

[0114] (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).

[0115] (3) Fiber Strength: Measurement was performed in accordance with JIS L1013 8.5.1, with a chuck distance of 10 mm and a pulling speed of 10 mm / min.

[0116] (4) Fiber elongation: Measured in accordance with JIS L1013 8.5.1, with a chuck distance of 10 mm and a pulling speed of 10 mm / min.

[0117] (5) Load: Using the values ​​measured in the above "(3) Fiber strength" and "(4) Fiber elongation", the load was calculated according to the following formula.

[0118] (6) Number of crimps: Measured in accordance with JIS L 1015:2010 8.12.1.

[0119] (7) Basis Weight: Measured in accordance with JIS L1906 (2000) 5.2 Mass per unit area.

[0120] (8) 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.

[0121] (9) Elongation of Nonwoven Fabric: 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.

[0122] (10) 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

[0123] 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 designated as cylinders 1, 2, 3, and 4, with cylinder 1 set to 280°C, cylinders 2 to 4 set to 325°C, the piping section set to 325°C, the screw rotation speed set to 700 rpm, and the screw peripheral speed set to 33.0 m / min.

[0124] A gear pump was installed downstream of the extruder, and the polymer was extruded through a metal nonwoven filter (product name: NF-10, manufactured by Nippon Seisen Co., Ltd.) into a nozzle (nozzle hole diameter: 0.8 mm, number of nozzle holes: 48) (total output: 66 g / min). The nozzle temperature at this time was 345°C. The residence time of the raw material, poly(2,6-dimethyl-1,4-phenylene ether), in the extruder was 0.29 minutes. The polymer extruded from the nozzle was wound at a spinning speed of 470 m / min. During winding, a spinning oil was applied using a gear pump with a capacity of 0.06 cc / rev (output: 4 g / min). The obtained fiber had a rearrangement structure (amount of rearrangement structure: 1.2 mol% relative to the total PPE units). The strength and elongation of the obtained PPE fiber were measured, and the raw yarn strength was calculated to be 21.1 cN / dtex·%. １／２ It was.

[0125] The obtained polyphenylene ether fiber (fineness: 22 dtex) was crimped using a commercially available crimper to produce polyphenylene ether staples. The crimping was carried out by heating the fiber to 100°C or higher with steam. The strength and elongation of the obtained crimped PPE fiber were measured, and the calculated elasticity was 19.7 cN / dtex·%. １／２ The strength retention rate and elongation retention rate were 96% and 93%, respectively.

[0126] 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 4.7 mm and a basis weight of 425 g / m. ２ The nonwoven fabric thus obtained was evaluated. The evaluation results are shown in Table 1.

[0127] Examples 2 to 4, 6, 7, Comparative Examples 1 and 2 Crimped PPE fibers and nonwoven fabrics were formed in the same manner as in Example 1, except that the PPE fiber forming conditions, the number of crimps, and the basis weight of the nonwoven fabric were changed. The evaluation results are shown in Table 1.

[0128] Example 5 Crimped PPE fibers and nonwoven fabrics were formed in the same manner as in Example 1, except that the PPE fiber forming conditions, number of crimps, and basis weight of the nonwoven fabric were changed to those shown in Table 1 and the average fiber length was changed from 89 mm to 64 mm. The evaluation results are shown in Table 1.

[0129]

[0130] As is clear from Table 1, the crimped PPE fibers of the present invention in Examples 1 to 7 had high strength retention and elongation retention, and were able to suppress the decrease in strength and elongation due to crimping processing. Nonwoven fabrics using such crimped PPE fibers were excellent in both strength and elongation.

[0131] On the other hand, in Comparative Examples 1 and 2, the crimped PPE fibers had low elasticity, and the obtained nonwoven fabrics were inferior in both strength and elongation.

[0132] REFERENCE SIGNS LIST 1 Hopper 2 Extruder 3 Gear pump 4 Filter medium 5 Spinning nozzle 6 Filter 7 Heat-retaining space 8 Introduction of inert gas 9 Heating torch 10 Piping 11 Piping

Claims

1. A crimped polyphenylene ether fiber having a fineness of 20 dtex or more and a crimp number of 2.5 pieces / 25 mm or more, the crimped polyphenylene ether fiber has a ripple of 15 cN / dtex / % or less, as expressed by the following formula: １／２ More than 50cN / dtex・% １／２ 1. A crimped polyphenylene ether fiber, characterized in that:

2. The crimped polyphenylene ether fiber according to claim 1, characterized in that the crimped polyphenylene ether fiber has a strength of 0.9 cN / dtex or more.

3. The crimped polyphenylene ether fiber according to claim 1, characterized in that the elongation of the crimped polyphenylene ether fiber is 110% or more.

4. The crimp strength of the polyphenylene ether fiber before crimping is 15 cN / dtex.%. １／２ 2. The crimped polyphenylene ether fiber according to claim 1, wherein 5. The crimped polyphenylene ether fiber according to claim 1, characterized in that the strength retention, expressed by the following formula, is 70% or more: Strength retention (%) = (strength of fiber after crimping / strength of fiber before crimping) x 100 6. The crimped polyphenylene ether fiber according to claim 1, characterized in that the elongation retention expressed by the following formula is 50% or more: Elongation retention (%) = (elongation of fiber after crimping / elongation of fiber before crimping) x 100 7. A nonwoven fabric comprising the crimped polyphenylene ether fiber according to any one of claims 1 to 6.

8. The strength of the nonwoven fabric is 450 g / m ２ 8. The nonwoven fabric according to claim 7, having a basis weight of 20 N / cm or more.

9. A molded product obtained by press molding the nonwoven fabric according to claim 7.

10. A flame-retardant nonwoven fabric obtained by subjecting the nonwoven fabric according to claim 7 to a flame-retardant treatment.

11. A flame-resistant molded product obtained by subjecting the molded product according to claim 9 to a flame-resistant treatment.

12. A method for producing the crimped polyphenylene ether fiber according to any one of claims 1 to 6, wherein the crimp represented by the following formula is 15 cN / dtex·% １／２ and subjecting the polyphenylene ether fiber having the above-mentioned diameter to a crimping process to obtain a crimped polyphenylene ether fiber having a number of crimps of 2.5 pieces / 25 mm or more.

13. A method for producing a nonwoven fabric, comprising the step of forming a web containing the crimped polyphenylene ether fiber according to any one of claims 1 to 6.

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