Fluororubber fiber, fluororubber nonwoven fabric, and method for producing fluororubber fiber

Abstract

One embodiment of the present invention relates to fluorine rubber fibers, a fluorine rubber nonwoven fabric or a method for producing fluorine rubber fibers; and the fluorine rubber in the fluorine rubber fibers is composed of at least one elastomer that is selected from among fluoroelastomers (FKM) and perfluoroelastomers (FFKM).

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a fluororubber fiber, a fluororubber nonwoven fabric, or a method for producing a fluororubber fiber. [Background technology]

[0002] Because fluororesins have extremely excellent properties, they are formed into fibers, which are then used to make nonwoven fabrics and are used in filters and printed circuit boards (for example, Patent Documents 1 and 2).

[0003] Meanwhile, in order to meet the stringent specifications required in fields such as the automotive, aerospace, oil and gas drilling, semiconductor and medical industries, fluororubbers with excellent heat resistance, oil resistance and chemical resistance, specifically fluoroelastomers (FKM) and perfluoroelastomers (FFKM), have been developed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-81918 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-49387 Summary of the Invention [Problem to be solved by the invention]

[0005] If fibers having the excellent properties of the fluororubber could be formed, it would be possible to obtain nonwoven fabrics and the like having these properties. However, unlike the above-mentioned fibers and nonwoven fabrics made from fluororesin, the reality is that no fibers or nonwoven fabrics made from fluororubber are currently known. One embodiment of the present invention provides fibers and nonwoven fabrics that take advantage of the properties of fluororubber, such as heat resistance, oil resistance, and chemical resistance. [Means for solving the problem]

[0006] As a result of extensive research into solving the above problems, the present inventors have found that the above problems can be solved by the following configuration examples, and have completed the present invention. An example of the configuration of the present invention is as follows.

[0007] [1] Fluorine rubber fiber, The fluororubber is at least one selected from a fluoroelastomer (FKM) and a perfluoroelastomer (FFKM). Fluorine rubber fiber.

[0008] [2] The fluororubber fiber according to [1], having an average fiber diameter of 50 μm or less.

[0009] [3] The fluororubber fiber according to [1] or [2], wherein the fluororubber has a Mooney viscosity (ML1+10) of 15 or more at 121°C measured in accordance with ASTM D 1646.

[0010] [4] The fluororubber fiber according to any one of [1] to [3], wherein the fluororubber comprises at least one selected from a crosslinked product of FKM and a crosslinked product of FFKM.

[0011] [5] A fluororubber nonwoven fabric comprising the fluororubber fiber according to any one of [1] to [4].

[0012] [6] Step 1: Spinning a fluoroelastomer composition containing at least one fluoroelastomer selected from fluoroelastomers (FKM) and perfluoroelastomers (FFKM); and Step 2: Crosslinking the fibers obtained in step 1 A method for producing a fluororubber fiber, comprising:

[0013] [7] The method for producing a fluororubber fiber according to [6], wherein the step 2 is a step of irradiating the fiber obtained in the step 1 with radiation. [Effects of the Invention]

[0014] According to one embodiment of the present invention, it is possible to provide a fiber and a nonwoven fabric having a fibrous shape while still making use of the properties of fluororubber, such as heat resistance, oil resistance, and chemical resistance. Furthermore, according to one embodiment of the present invention, it is possible to provide a fiber and a nonwoven fabric that maintain a desired shape, such as a fibrous shape or a porous shape, for a long period of time and that is flexible and stretchable. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 shows SEM images of the fibers (nonwoven fabrics) obtained in Examples 1 and 3 and Comparative Example 1. [Figure 2] FIG. 2 is an SEM image of the fibers (nonwoven fabrics) obtained in Examples 4 and 5. DETAILED DESCRIPTION OF THE INVENTION

[0016] <Fluororubber fiber> A fluororubber fiber according to one embodiment of the present invention (hereinafter also referred to as "the fiber") is a fiber made of at least one type of fluororubber selected from fluoroelastomers (FKM) and perfluoroelastomers (FFKM).

[0017] The present fiber may be a fiber made only of the fluororubber, or a fiber containing the fluororubber and an additive other than the fluororubber.Furthermore, the present fiber may be a fiber obtained by subjecting these fibers to a treatment such as plating or hydrophilic treatment. When a polymer other than the fluororubber is used as the other additive, the content of the fluororubber in the fiber is 50% by mass or more relative to 100% by mass of the total of the fluororubber and the polymer.

[0018] The present fiber may be used as a single fiber as is, or may be used as a thread made by twisting multiple fibers together, or may be used as an additive such as a reinforcing material for resin molded products. However, it is preferable to use the fiber as a nonwoven fabric or woven fabric made from multiple fibers, and it is more preferable to use the fiber as a nonwoven fabric.

[0019] The fiber can be used as filters, separators, substrates, base materials, etc. for automotive components, aerospace components, chemical plants, semiconductor-related equipment, medical components, etc. Furthermore, according to one embodiment of the present invention, it is possible to provide flexible and stretchable fibers and nonwoven fabrics that maintain the desired shape, such as a fibrous shape or porous shape, for a long period of time, making it suitable for use as materials that require flexibility, stretchability, etc., such as flexible substrates (e.g., flexible printed circuit boards) and wearable components. Furthermore, according to one embodiment of the present invention, it is possible to obtain fibers and nonwoven fabrics that are highly breathable, water-repellent, and stain-resistant, making it suitable for use as wearable components.

[0020] <Fluororubber> The fluororubber is at least one selected from fluoroelastomers (FKM) and perfluoroelastomers (FFKM). Among these, FKM is preferred because of its ease of spinning. Furthermore, FKM has excellent chemical resistance and heat resistance, as well as excellent resistance to stains, dirt, oxidation, and ultraviolet rays. Therefore, by using FKM as the fluororubber, the fiber can be suitably used as a material for wearable components. The fluororubber is at least one selected from FKM and FFKM, and the "at least one selected from FKM and FFKM" referred to here may include at least one selected from a crosslinked FKM and a crosslinked FFKM. From the viewpoint of better maintaining the fiber shape (porous shape, nonwoven fabric shape), it is preferable to carry out a crosslinking step after the spinning step, as described below. In this case, the fluororubber contained in the fiber includes a crosslinked FKM and / or a crosslinked FFKM, and is preferably a crosslinked FKM and / or a crosslinked FFKM. The fiber may contain two or more types of fluororubbers.

[0021] [FFKM] The FFKM is not particularly limited, but examples thereof include polymers that do not contain hydrogen atoms (carbon-hydrogen bonds) in the polymer main chain (excluding the terminals), and specifically include tetrafluoroethylene (TFE)-perfluorovinyl ether copolymers, with copolymers that contain TFE-derived structural units and perfluorovinyl ether-derived structural units and, if necessary, further contain structural units derived from a crosslinking site-containing monomer being preferred.

[0022] Suitable examples of the perfluorovinyl ether include perfluoro(alkyl vinyl ether) and perfluoro(alkoxyalkyl vinyl ether).

[0023] The perfluoro(alkyl vinyl ether) may be a compound in which the alkyl group has, for example, 1 to 10 carbon atoms. Specific examples include perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether), and preferably perfluoro(methyl vinyl ether).

[0024] Examples of the perfluoro(alkoxyalkyl vinyl ether) include compounds in which the number of carbon atoms in the group bonded to the vinyl ether group (CF═CFO—) is, for example, 3 to 15. Specific examples include: CF2=CFOCF2CF(CF3)OC n F 2n+1 , CF2=CFO(CF2)3OC n F 2n+1 , CF2=CFOCF2CF(CF3)O(CF2O) m C n F 2n+1 , CF2=CFO(CF2)2OC n F 2n+1 etc. In these formulas, n is, independently, for example, 1 to 5, and m is, for example, 1 to 3.

[0025] The FFKM can be imparted with crosslinkability by including a structural unit derived from a crosslinking moiety-containing monomer. The crosslinking moiety refers to a moiety capable of undergoing a crosslinking reaction, and examples thereof include a nitrile group, a halogen group (e.g., an I group or a Br group), and a perfluorophenyl group.

[0026] Examples of crosslinking moiety monomers having a nitrile group as a crosslinking moiety include nitrile group-containing perfluorovinyl ethers, and specific examples thereof include: CF2=CFO(CF2) n OCF(CF3)CN (n is, for example, 2 to 4), CF2=CFO(CF2) n CN (n is, for example, 2 to 12), CF2=CFO[CF2CF(CF3)O] m (CF2) n CN (n is, for example, 1 to 4, m is, for example, 1 to 5), CF2=CFO[CF2CF(CF3)O] n CF2CF(CF3)CN (n is, for example, 0 to 4) etc.

[0027] Examples of crosslinking moiety-containing monomers having a halogen group as a crosslinking moiety include halogen group-containing perfluorovinyl ethers, and specific examples thereof include compounds in which the nitrile group in the above-mentioned specific examples of nitrile group-containing perfluorovinyl ethers is replaced with a halogen group.

[0028] In FFKM, the content of structural units derived from TFE is preferably 50.0 to 79.9 mol %, the content of structural units derived from perfluorovinyl ether is preferably 20.0 to 46.9 mol %, and the content of structural units derived from crosslinking site-containing monomers is preferably 0.1 to 2.0 mol %.

[0029] [FKM] Examples of FKM include fluoroelastomers other than the above-mentioned FFKM, and are not particularly limited, but specific examples include vinylidene fluoride-hexafluoropropylene polymers; vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene polymers; tetrafluoroethylene-propylene polymers; vinylidene fluoride-propylene-tetrafluoroethylene polymers; ethylene-tetrafluoroethylene-perfluoromethylvinyl ether polymers; vinylidene fluoride-tetrafluoroethylene-perfluoromethylvinyl ether polymers, and vinylidene fluoride-perfluoromethylvinyl ether polymers. Among these, ternary polymers are preferred because of their excellent heat resistance, chemical resistance, etc., and vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene polymers are more preferred. To impart crosslinkability to the FKM, the FKM may contain structural units derived from crosslinking site-containing monomers, as in the section on FFKM above.

[0030] The fluororubber preferably has a Mooney viscosity (ML1+10) at 121° C. measured in accordance with ASTM D 1646 of 15 or more, more preferably 20 or more, and preferably 100 or less. It is preferable that the Mooney viscosity of the fluororubber is within the above range because it is easy to spin and the fiber shape (porous shape, nonwoven fabric shape) formed in the spinning step can be maintained even without performing a crosslinking step after the spinning step. When the Mooney viscosity (ML1+10) of the fluororubber at 121°C measured in accordance with ASTM D 1646 is less than 15, it tends to be difficult to form the fluororubber into a fiber shape (porous shape, nonwoven fabric shape) by a spinning process. When the fluororubber is a crosslinked product, the Mooney viscosity refers to the viscosity of the fluororubber before crosslinking.

[0031] The weight average molecular weight of the fluororubber measured by gel permeation chromatography is preferably 1×10 because it has excellent solubility and spinning stability and can easily produce fibers with excellent mechanical strength. 3~5×10 7 , more preferably 1 × 10 4 ~1×10 7 is.

[0032] The fluorine content in the fluororubber is preferably 55% by mass or more, more preferably 62% by mass or more, particularly preferably 64% by mass or more, and is preferably 80% by mass or less, more preferably 78% by mass or less. When the fluorine content is within the above range, the fiber is easy to spin and has excellent chemical resistance. The fluorine content can be measured or calculated by solid-state nuclear magnetic resonance (NMR) or mass spectrometry (MS spectrometry), or the like.

[0033] The content of the fluororubber in the present fiber is preferably 20% by mass or more, more preferably 30% by mass or more, and particularly preferably 50% by mass or more. There is no particular upper limit to the content, but when the present fiber does not contain the following filler, it may be 100% by mass. When the content of the fluororubber is within the above range, it is possible to easily obtain fibers that fully exhibit the physical properties of the fluororubber, such as chemical resistance and heat resistance.

[0034] <Other additives> In addition to the fluororubber, the fiber may contain other additives that have been conventionally known and have been blended into fibers, as needed, within the scope of not impairing the effects of the present invention. Examples of such additives include polymers other than the fluororubber (e.g., fluororesins), crosslinking agents, co-crosslinking agents, antioxidants, antioxidants, vulcanization accelerators, stabilizers, silane coupling agents, fillers (reinforcing agents), plasticizers, flame retardants, waxes, and lubricants. The other additives may each be used alone or in combination of two or more.

[0035] The crosslinking agent may be appropriately selected depending on the fluororubber used. For example, when FKM is used, examples of the crosslinking agent include peroxide-based crosslinking agents, polyamine-based crosslinking agents, and polyol-based crosslinking agents. When FFKM is used, examples of the crosslinking agent include peroxide-based crosslinking agents, bisphenol-based crosslinking agents, triazine-based crosslinking agents, oxazole-based crosslinking agents, imidazole-based crosslinking agents, and thiazole-based crosslinking agents.

[0036] Examples of peroxide-based crosslinking agents include 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, di-t-butyl peroxide, t-butyldicumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-(t-butylperoxy)hexyne-3, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, α,α'-bis(t-butylperoxy-m-isopropyl)benzene, t-butylperoxyisopropyl carbonate, and p-chlorobenzoyl peroxide.

[0037] As the co-crosslinking agent, a conventionally known co-crosslinking agent (crosslinking assistant) can be used. Examples of the co-crosslinking agent include compounds (polyfunctional monomers) capable of co-crosslinking by radicals, such as triallyl isocyanurate, triallyl cyanurate, triallyl formal, triallyl trimellitate, N,N'-m-phenylene bismaleimide, dipropargyl terephthalate, diallyl phthalate, and tetraallyl terephthalamide. Among these, it is preferable to include triallyl isocyanurate in terms of reactivity and the heat resistance of the resulting fiber.

[0038] Examples of the filler include functional fillers (e.g., thermally conductive particles, electrically conductive particles, insulating particles, reinforcing fibers) appropriate for the intended use of the fiber, and specific examples include carbon materials (e.g., carbon black, nanocarbon, carbon nanotubes, graphite), silica, alumina, zinc oxide, titanium dioxide, clay, talc, diatomaceous earth, barium sulfate, silicate compounds (silicates, etc.), calcium carbonate, magnesium carbonate, calcium oxide, mica, aluminum hydroxide, metal (e.g., silver) particles, and resin fine particles. The shape of the filler is not particularly limited, and examples thereof include particles and fibers.

[0039] When the present fiber contains the filler, the content of the filler in the present fiber is preferably 0.1 to 80% by mass, more preferably 1 to 70% by mass, from the viewpoint that the physical properties of the fluororubber, such as chemical resistance and heat resistance, can be exhibited and a fiber in which the physical properties of the filler can be fully exhibited can be easily obtained.

[0040] <The shape of this fiber> The average fiber diameter of the present fibers is preferably 50 μm or less, more preferably 0.05 to 50 μm, even more preferably 0.1 to 20 μm, and particularly preferably 0.3 to 10 μm. When the average fiber diameter is within the above range, it is possible to form a nonwoven fabric or the like that exhibits high flexibility, and it is preferable in that even when a thin nonwoven fabric or the like is formed, the distribution uniformity of the fibers can be increased.

[0041] The average fiber diameter of the present fiber can be adjusted by appropriately selecting the conditions for forming the fiber. For example, when the fiber is produced by an electrospinning method, the average fiber diameter of the obtained fiber tends to be reduced by reducing the humidity, reducing the nozzle diameter, increasing the applied voltage, or increasing the voltage density during electrospinning.

[0042] The average fiber diameter in this specification is an average value calculated based on the measurement results obtained by observing the fiber (group) to be measured with a scanning electron microscope (SEM) (magnification: 2000x), randomly selecting 20 fibers from the obtained SEM image, and measuring the fiber diameter (long diameter) of each of these fibers.

[0043] The fiber diameter variation coefficient of the present fiber, calculated by the following formula, is preferably 0.7 or less, more preferably 0.01 to 0.5. When the fiber diameter variation coefficient is within the above range, the fiber diameter becomes uniform, the mechanical strength is excellent, and nonwoven fabrics obtained using the fiber have a higher porosity. Coefficient of variation of fiber diameter = standard deviation / average fiber diameter (Note that the "standard deviation" refers to the standard deviation of the fiber diameters of the 20 fibers.)

[0044] The fiber length of the present fiber is not particularly limited, but is preferably 0.1 to 1000 mm, more preferably 0.5 to 100 mm, and even more preferably 1 to 50 mm.

[0045] <Manufacturing method of this fiber> The method for producing the present fiber is not particularly limited as long as it can form a fibrous material containing FKM and / or FFKM, but a production method including step 1 of spinning a fluororubber composition containing at least one fluororubber selected from FKM and FFKM is preferred.

[0046] [Process 1] Step 1 , place Fibers of the desired shape can be easily spun, fibers with small fiber diameters can be obtained, and nonwoven fabrics obtained using the fibers tend to have high porosity and a large specific surface area. , electric Boundary spinning is preferred. For example, when step 1 is performed by electrospinning, the obtained fiber may be formed on a collector, and in this case, a nonwoven fabric may be formed on the collector. Therefore, one embodiment of the method for producing the fiber is also a method for producing a nonwoven fabric.

[0047] Electrospinning When forming fibers by electrospinning, a fluororubber composition containing the above-mentioned fluororubber and, if necessary, a solvent is preferably used. The proportion of the fluororubber contained in the fluororubber composition is, for example, 5 to 100 mass %, preferably 5 to 80 mass %, and more preferably 10 to 70 mass %. The fluororubbers may be used alone or in combination of two or more.

[0048] The solvent is not particularly limited as long as it can dissolve or disperse the fluororubber, and examples thereof include water, dimethylacetamide, dimethylformamide, tetrahydrofuran, methylpyrrolidone, xylene, acetone, methyl ethyl ketone, chloroform, ethylbenzene, cyclohexane, benzene, sulfolane, methanol, ethanol, phenol, pyridine, propylene carbonate, acetonitrile, trichloroethane, hexafluoroisopropanol, and diethyl ether. These solvents may be used alone or in combination of two or more. The solvent is contained in the fluororubber composition in an amount of, for example, 0 to 90% by mass, preferably 10 to 90% by mass, and more preferably 20 to 80% by mass.

[0049] The fluororubber composition may further contain other components that may be contained in the present fiber, such as other additives, surfactants, dispersants, charge control agents, viscosity modifiers, fiber-forming agents, etc. Each of these other components may be used alone or in combination of two or more.

[0050] When carrying out the following step 2 in producing the present fiber, a fluororubber composition containing a crosslinking agent and / or a co-crosslinking agent may be used, or a fluororubber composition not containing a crosslinking agent and / or a co-crosslinking agent may be used. However, when a crosslinking agent and / or a co-crosslinking agent is used, if the following step 2 is not carried out, the crosslinking agent and / or the co-crosslinking agent may become impurities, which may result in a decrease in the tensile properties of the fiber, so it is preferable to carry out the following step 2. Examples of the crosslinking agent and co-crosslinking agent include the same crosslinking agents and co-crosslinking agents as those described in the section on other additives. When a crosslinking agent is used, the amount of the crosslinking agent used is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the fluororubber. When a co-crosslinking agent is used, the amount of the co-crosslinking agent used is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the fluororubber.

[0051] When the fluororubber has low solubility in the solvent, the fluororubber composition preferably contains one or more fiber-forming agents from the viewpoint of maintaining the fluororubber in a fibrous form during spinning. The fiber-forming agent is preferably an organic polymer having high solubility in a solvent, and examples thereof include polyethylene oxide, polyethylene glycol, dextran, alginic acid, chitosan, starch, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, polyacrylamide, cellulose, and polyvinyl alcohol. When the fiber-forming agent is used, the amount used is, for example, 0.1 to 15 mass %, preferably 1 to 10 mass %, in the fluororubber composition, depending on the viscosity of the solvent and the solubility in the solvent.

[0052] The conditions for electrospinning include, for example, the following conditions. The applied voltage (the voltage applied between the spinning nozzle and the fiber collecting collector) is preferably 1 to 100 kV, more preferably 5 to 50 kV, and even more preferably 10 to 40 kV. The spinning distance (the distance between the spinning nozzle and the fiber collecting collector) is preferably 5 to 30 cm. The discharge rate of the fluororubber composition is preferably 0.01 to 3 ml / min. The tip diameter (outer diameter) of the spinning nozzle used for electrospinning is preferably 0.1 to 2.0 mm, more preferably 0.2 to 1.6 mm. The spinning atmosphere does not need to be particularly controlled, but it is preferable that the relative humidity is, for example, 10 to 50%, and the temperature is, for example, 10 to 35°C.

[0053] The fiber collecting collector can be a rotary collector or a flat collector. When a rotary collector is used, the fibers ejected from the spinning nozzle are wound onto the drum by rotating the drum, thereby obtaining a nonwoven fabric in which the fibers are oriented in a certain direction. The rotation speed of the rotary collector is, for example, 50 to 5,000 revolutions per minute. When a flat fiber collecting collector is used, a nonwoven fabric made of unoriented fibers can be obtained.

[0055] [Process 2] When producing the present fiber, only step 1 may be carried out. However, it is preferable to include step 2, in which the fiber obtained in step 1 is crosslinked, because the fiber shape (porous shape, nonwoven fabric shape) obtained in step 1 can be maintained for a long period of time and fibers with improved tensile properties such as tensile strength and tensile modulus can be easily obtained. By undergoing step 2, it is possible to obtain fibers containing at least one selected from a crosslinked FKM and a crosslinked FFKM.

[0056] Specific examples of step 2 include a step of irradiating the fibers obtained in step 1 with radiation (radiation crosslinking) and a step of applying heat to the fibers obtained in step 1 (thermal crosslinking). Of these, radiation crosslinking is preferred because it allows crosslinking treatment in a short time and makes it possible to easily maintain the fiber shape (porous shape, nonwoven fabric shape) obtained in step 1. The fibers obtained in step 1 may be fibers immediately after being extruded from the nozzle or the like, or may be fibers after being accumulated on a collector or the like.

[0057] ·Radiation crosslinking Examples of the radiation include X-rays, gamma rays, electron beams, proton beams, neutron beams, heavy particle beams, alpha rays, and beta rays, and among these, electron beams are preferred. The radiation to be irradiated may be of one type alone or of two or more types.

[0058] The radiation crosslinking may be carried out by a conventionally known method, but the conditions for irradiation with electron beams include, for example, the following conditions. It is desirable to irradiate with electron beams so that the absorbed dose is preferably 10 to 500 kGy, more preferably 20 to 300 kGy. When irradiating with radiation, it is preferable to carry out the irradiation in an atmosphere of an inert gas such as nitrogen or argon, since the crosslinking reaction is less likely to be inhibited and fibers having excellent mechanical properties can be easily obtained.

[0059] ·Thermal crosslinking The heating conditions for the thermal crosslinking may be set depending on the composition of the fluororubber composition used, and examples include a heating temperature of 150 to 200° C. and a heating time of 1 to 24 hours.

[0060] <Fluororubber nonwoven fabric> The fluororubber nonwoven fabric according to one embodiment of the present invention is not particularly limited as long as it contains the present fibers, and examples thereof include nonwoven fabrics made from the present fibers. The fibers constituting the nonwoven fabric preferably contain a crosslinked FKM and / or a crosslinked FFKM, and more preferably contain a crosslinked FKM, in order to provide a nonwoven fabric with excellent shape retention, chemical resistance, and tensile properties such as tensile strength and tensile modulus.

[0061] The nonwoven fabric can be used as a filter, separator, substrate, base material, etc. for automobile parts, aerospace parts, chemical plants, semiconductor-related equipment, medical equipment, etc. Moreover, according to one embodiment of the present invention, a flexible and stretchable nonwoven fabric can be provided that maintains a desired shape, such as a fibrous or porous shape, for a long period of time, and therefore can be suitably used as a material that requires flexibility, stretchability, etc., such as flexible substrates (e.g., flexible printed circuit boards) and wearable components. Furthermore, according to one embodiment of the present invention, a nonwoven fabric that has excellent breathability and water repellency and is stain-resistant can be obtained, and from this point of view, it can also be suitably used as a wearable component.

[0062] The porosity of the nonwoven fabric is not particularly limited, but is, for example, 0.1 to 95% by volume, and preferably 30 to 90% by volume. The porosity can be calculated using the following formula from the difference between the theoretical volume calculated assuming no voids based on the specific gravity of the material constituting the nonwoven fabric and the measured mass of the nonwoven fabric, and the actual volume calculated by measuring the dimensions of the nonwoven fabric. Porosity (volume%) = (1 - (theoretical volume / measured volume)) x 100

[0063] The basis weight of the nonwoven fabric is preferably 100 g / m 2 or less, more preferably 1 to 80 g / m 2 is.

[0064] The thickness of the nonwoven fabric may be appropriately selected depending on the application of the nonwoven fabric, but is usually 5 μm to 1 mm, preferably 10 to 500 μm. The nonwoven fabric is formed by accumulating the fibers in a sheet form, and such nonwoven fabrics and woven fabrics may be composed of a single layer or two or more layers of different materials or fiber diameters.

[0065] To form a nonwoven fabric using the fibers, specifically, for example, a step of forming fibers by electrospinning or the like and a step of accumulating the formed fibers into a sheet to form a nonwoven fabric may be carried out simultaneously, or after the step of forming fibers, a step of accumulating the formed fibers into a sheet to form a nonwoven fabric may be carried out using a wet papermaking method, a water punching method, a chemical bonding method, a thermal bonding method, a spun bonding method, a needle punching method, a stitch bonding method, or the like. [Example]

[0066] Next, the present invention will be described in more detail by showing examples, but the present invention is not limited to these examples.

[0067] [Example 1] A fluororubber composition was prepared by dissolving FKM (Dai-El G901H, Daikin Industries, Ltd., Mooney viscosity (ML1+10): 53 at 121°C measured in accordance with ASTM D 1646) in methyl ethyl ketone (special grade, Fujifilm Wako Pure Chemical Industries, Ltd.) to a concentration of 20% by mass, and FKM fibers were directly spun onto a collector covered with aluminum foil using an electrospinning apparatus (MEC Co., Ltd.) under the following conditions. The average fiber diameter of the resulting FKM fibers was approximately 1 μm.

[0068] (Spinning conditions) Voltage: 15kV Feed Rate: 2.0 ml / min Syringe diameter: 10.0 mm Rotation: 100 rpm

[0069] The obtained FKM fiber was observed at magnifications of 500x and 2000x using an SEM (S-3400N, manufactured by Hitachi High-Technologies Corporation; the same SEM was used below). The upper left of Figure 1 is an SEM image of the obtained FKM fiber at magnification of 500x, and the lower left of Figure 1 is an SEM image of the obtained FKM fiber at magnification of 2000x. The SEM image in Figure 1 is an image of the obtained fibers, and can also be said to be an image of the obtained nonwoven fabric. The obtained FKM fiber retained the same shape as immediately after spinning even after 24 hours, demonstrating excellent shape stability.

[0070] [Example 2] FKM (Dai-el G901H) was dissolved in methyl ethyl ketone (special grade, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to a concentration of 10 mass%, and TAIC (triallyl isocyanurate, manufactured by Mitsubishi Chemical Corporation) was added in an amount of 4 mass parts per 100 mass parts of FKM to prepare a fluororubber composition. FKM fibers were then directly spun onto a collector covered with aluminum foil using an electrospinning apparatus (manufactured by MEC Co., Ltd.) under the following conditions. The average fiber diameter of the resulting FKM fibers was approximately 1 μm.

[0071] (Spinning conditions) Voltage: 15kV Feed Rate: 2.0 ml / min Syringe diameter: 10.0 mm Rotation: 100 rpm

[0072] The resulting FKM fiber showed a similar SEM image to the fiber obtained in Example 1. The obtained FKM fiber retained the same shape as immediately after spinning even after 24 hours, demonstrating excellent shape stability.

[0073] [Example 3] A fluororubber composition was prepared by dissolving FKM (Dai-el G902, Daikin Industries, Ltd., Mooney viscosity (ML1+10): 21 at 121°C measured according to ASTM D 1646) in methyl ethyl ketone (special grade, Fujifilm Wako Pure Chemical Industries, Ltd.) to a concentration of 20% by mass, and FKM fibers were directly spun onto a collector covered with aluminum foil using an electrospinning apparatus (MEC Co., Ltd.) under the following conditions. The average fiber diameter of the resulting FKM fibers was approximately 2.3 μm.

[0074] (Spinning conditions) Voltage: 15kV Feed Rate: 2.0 ml / min Syringe diameter: 10.0 mm Rotation: 300 rpm

[0075] The obtained FKM fiber immediately after spinning was observed using an SEM at magnifications of 500x and 2000x. The upper center of Figure 1 is an SEM image of the obtained FKM fiber at magnifications of 500x, and the lower center of Figure 1 is an SEM image of the obtained FKM fiber at magnifications of 2000x. The obtained FKM fiber tended to lose its shape immediately after spinning, so it was irradiated with an electron beam in the same manner as in Example 4 before the shape immediately after spinning was lost.

[0076] [Comparative Example 1] A fluororubber composition was prepared in the same manner as in Example 1, except that an FKM (Dai-el G101, liquid rubber manufactured by Daikin Industries, Ltd.) was used so that the concentration was 10 mass %, and an FKM formed body was produced on a collector covered with aluminum foil using an electrospinning device (manufactured by MEC Co., Ltd.). However, because the solution sprayed onto the collector was in a spray form, the obtained FKM formed body did not have a fibrous shape.

[0077] The resulting FKM formed body was observed using an SEM at magnifications of 500x and 2000x. The upper right of Figure 1 is an SEM image of the resulting FKM formed body at a magnification of 500x, and the lower right of Figure 1 is an SEM image of the resulting FKM formed body at a magnification of 2000x.

[0078] [Example 4] The FKM fiber obtained in Example 1 was irradiated with electron beams (EB) using an EB device (manufactured by Iwasaki Electric Co., Ltd., CB250 / 30 / 20mA). The irradiation was carried out at room temperature (21°C) under N2, with an absorbed dose of 100 kGy. The conveying speed was 5 m / min.

[0079] The fibers (nonwoven fabric) obtained by electron beam irradiation were observed using an SEM at a magnification of 2000. The results are shown in the upper left of Figure 2. The electron beam irradiated fibers were then immersed in methyl ethyl ketone for two days to confirm their state. An SEM image (magnification 2000x) taken after two days of immersion in methyl ethyl ketone is shown in the upper right of Figure 2. Although the fibers swelled slightly after immersion in methyl ethyl ketone, it is believed that crosslinking allowed them to maintain their fiber shape (porous shape, nonwoven fabric shape) even after immersion in methyl ethyl ketone.

[0080] [Example 5] Electron beam irradiation was carried out in the same manner as in Example 4, except that the FKM fiber obtained in Example 2 was used. The fibers (nonwoven fabric) obtained by electron beam irradiation were observed using an SEM at a magnification of 2000. The results are shown in the lower left of Figure 2. The fibers after electron beam irradiation were immersed in methyl ethyl ketone for two days to confirm their state. An SEM image (magnification: 2000x) after immersion in methyl ethyl ketone for two days is shown in the lower right of Figure 2. It is believed that the crosslinking had progressed more than in the fibers obtained in Example 4, and therefore the fibers did not swell even after immersion in methyl ethyl ketone, and were able to maintain their fiber shape (porous shape, nonwoven fabric shape).

[0081] [Example 6] Electron beam irradiation was carried out in the same manner as in Example 4, except that the FKM fiber obtained in Example 3 was used. After electron beam irradiation, the fibers were immersed in methyl ethyl ketone for two days, and the state of the fibers was checked. It was found that the fiber shape (porous shape, nonwoven fabric shape) was maintained even after immersion in methyl ethyl ketone.

[0082] [Example 7] A nonwoven fabric having a thickness of about 38 μm was produced on a collector to which aluminum foil was attached in the same manner as in Example 1, except that the spinning time was changed to 1 hour.

[0083] [Example 8] The nonwoven fabric obtained in Example 7 was irradiated with electron beams (EB) using an EB device (manufactured by Iwasaki Electric Co., Ltd., CB250 / 30 / 20mA). The irradiation was carried out at room temperature (21°C) under N2, with an absorbed dose of 100 kGy. The conveying speed was 5 m / min.

[0084] [Example 9] A nonwoven fabric was produced on a collector with aluminum foil attached in the same manner as in Example 3, except that the spinning time was changed to 1 hour. The produced nonwoven fabric was irradiated with an electron beam in the same manner as in Example 8.

[0085] Comparative Example 2 Spinning was carried out in the same manner as in Example 7, except that FKM (Dai-el G101) was used instead of FKM (Dai-el G901H). However, the mixture was in a spray form and could not be made into fibers.

[0086] <Tensile test evaluation> Each of the nonwoven fabrics obtained in Examples 7 to 9 was punched into a JIS No. 3 dumbbell shape, and then a tensile test was performed at a speed of 1.0 mm / sec using a tensile tester (a small tabletop tester, manufactured by Shimadzu Corporation). The tensile strength and tensile modulus were calculated from the stress and elongation measured at that time. Tensile strength σ max is the maximum tensile stress applied during the tensile test, and the maximum load F max The cross-sectional area A was calculated using the following formula: σ max =F max / A The tensile modulus E was calculated from the ratio of the tensile stress σ within the tensile proportional limit to the corresponding strain ε using the following formula. E=σ / ε The results are shown in Table 1. The results in Table 1 show the average value of four tensile tests carried out using four pieces of each of the nonwoven fabrics obtained in Examples 7 to 9.

[0087] [Table 1]

[0088] As can be seen from FIG. 2, the crosslinking treatment was able to be carried out while maintaining the porous structure, and a comparison of Examples 7 and 8 in Table 1 shows that the tensile strength was improved by undergoing the crosslinking step. From the above, it can be said that according to one embodiment of the present invention, a flexible and stretchable porous nonwoven fabric structure containing fluororubber fibers was successfully produced.

[0089] [Example 10] In Example 2, a nonwoven fabric having a thickness of about 38 μm was produced on a collector to which aluminum foil was attached in the same manner as in Example 2, except that the spinning time was changed to 1 hour.

[0090] [Example 11] The nonwoven fabric obtained in Example 10 was irradiated with electron beams (EB) using an EB device (manufactured by Iwasaki Electric Co., Ltd., CB250 / 30 / 20mA). The irradiation was carried out at room temperature (21°C) under N2, with an absorbed dose of 100 kGy. The conveying speed was 5 m / min.

[0091] The nonwoven fabrics obtained in Examples 10 and 11 were subjected to tensile tests in the same manner as described above. The results are shown in Table 2. The results in Table 2 show the average values ​​of four tensile tests carried out using four pieces of each of the nonwoven fabrics obtained in Examples 10 and 11.

[0092] [Table 2]

[0093] As can be seen from FIG. 2, the crosslinking treatment was able to be carried out while maintaining the porous structure, and a comparison of Examples 10 and 11 in Table 2 shows that the tensile strength was improved by undergoing the crosslinking step. Furthermore, Table 2 shows that when a co-crosslinking agent (TAIC) was added, the tensile modulus (rubber hardness) could also be improved by carrying out the crosslinking step. From the above, it can be said that according to one embodiment of the present invention, a flexible and stretchable porous nonwoven fabric structure containing fluororubber fibers was successfully produced.

Claims

1. Fluorine rubber fiber, the fluororubber is at least one selected from a fluoroelastomer (FKM) and a perfluoroelastomer (FFKM), the fluororubber has a Mooney viscosity (ML1+10) at 121°C measured in accordance with ASTM D 1646 of 15 or more and 100 or less; Fluororubber fibers having an average fiber diameter of 50 μm or less.

2. The fluororubber fiber according to claim 1, wherein the fluororubber comprises at least one selected from a crosslinked product of FKM and a crosslinked product of FFKM.

3. A fluororubber nonwoven fabric comprising the fluororubber fiber according to claim 1 or 2.

4. Step 1: electrospinning a fluororubber composition containing at least one fluororubber selected from fluoroelastomers (FKM) and perfluoroelastomers (FFKM); and Step 2: Crosslinking the fibers obtained in step 1 Including, The fluororubber has a Mooney viscosity (ML1+10) at 121°C measured in accordance with ASTM D 1646 of 15 or more and 100 or less. Fluororubber fiber manufacturing method.

5. The method for producing a fluororubber fiber according to claim 4, wherein the step 2 is a step of irradiating the fiber obtained in the step 1 with radiation.

6. Step 1: electrospinning a fluororubber composition containing at least one fluororubber selected from fluoroelastomers (FKM) and perfluoroelastomers (FFKM); and Step 2 includes crosslinking the fibers obtained in step 1, The fluororubber has a Mooney viscosity (ML1+10) at 121°C measured in accordance with ASTM D 1646 of 15 or more and 100 or less. Manufacturing method of fluororubber nonwoven fabric.

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