JP7019290B2 - Electrolyte membrane reinforcement and electrolyte membrane - Google Patents

Description

The present invention relates to a reinforcing material for an electrolyte membrane used in a fuel cell, an all-solid-state secondary battery, or the like, and an electrolyte membrane containing the reinforcing material.

The electrolyte film is a film that has the property of an insulator that does not electrically short-circuit the negative electrode and the positive electrode among the electrolyte films (the property of passing only ions without passing electrons), especially fuel cells and all-solids. A secondary battery or the like has a property of blocking the permeation of either a cation or an anion and allowing the other ion to pass through.

In the case of a fuel cell, the electrolyte membrane includes high proton or hydroxide ion conductivity that leads to high power generation characteristics, power generation durability, electrolyte resistance, mechanical properties (mechanical strength), heat resistance, and fuel (gas). Or it is necessary to satisfy various properties such as impermeable property of liquid). Further, in the case of an all-solid-state secondary battery, it is necessary to satisfy various properties such as high ionic conductivity such as lithium ion, mechanical properties (mechanical strength), safety, and stability. As described above, the electrolyte membrane can be said to be an important factor that influences the performance of fuel cells and all-solid-state secondary batteries. The electrolyte membrane reinforcing material is used for the purpose of improving the mechanical strength of such an electrolyte membrane.

As the solid polymer type electrolyte membrane reinforcing material constituting such an electrolyte membrane, in Patent Document 1, a fiber composed of PVDF (polyvinylidene fluoride), PES (polyether sulfone), and PES / PVDF compound is used. ing. Further, in Patent Document 2, a non-woven fabric made of a resin such as PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), PET, and aramid is used. Further, in Patent Document 3, a polyacrylonitrile nonwoven fabric, a stretched polytetrafluoroethylene porous membrane, a biaxially oriented polypropylene porous membrane, and a polyester nonwoven fabric are used.

Further, in Patent Document 4, porous bodies of polysulfone and polyethersulfone are used, and these porous bodies are immersed in water after casting a solution in which these resins are dissolved in a dimethylformamide solution. It is manufactured by precipitating.

Special Table 2013-51386 No. Japanese Unexamined Patent Publication No. 2006-269266 Japanese Unexamined Patent Publication No. 2013-77554 Japanese Patent Application Laid-Open No. 2003-297393

Patent Documents 1 to 4 describe PEEK as a material for the electrolyte membrane reinforcing material. However, since PEEK is a resin having excellent solvent resistance so that it is said that there is no solvent that can be dissolved, the non-woven fabric made of PEEK fiber cannot be produced by the methods described in Patent Documents 1 to 4. In particular, in the method of solubilizing the resin described in Patent Documents 1 and 2 and then electrolytically spinning, in order to dissolve PEEK and perform electrolytic spinning, it is necessary to significantly modify the resin in order to impart solvent solubility. However, such PEEK has significantly deteriorated chemical resistance (electrolyte resistance) and is not suitable for applications requiring remarkable chemical resistance (electrolyte resistance) such as an electrolyte membrane reinforcing material. Further, when PEEK is dissolved using concentrated sulfuric acid as a solvent as described in Patent Document 4 to obtain a porous body, the chemical resistance of the obtained porous body is significantly lowered.

The resin used as the electrolyte membrane reinforcing material in Patent Documents 1 to 4 has insufficient heat resistance for use as the electrolyte membrane, and its physical properties such as proton conductivity deteriorate due to long-term use in a high temperature environment. There is concern about deterioration of power generation performance (for example, PVDF continuous use temperature of about 150 ° C., PES continuous use temperature of about 180 ° C.). Further, the resins used in Patent Documents 1 to 4 are easily dissolved in a polar solvent such as alcohol, and are not necessarily excellent in electrolyte resistance.

Further, the porous body of Patent Document 4 has holes only on the surface of the film and has almost no through holes, so that the proton conductivity for use as an electrolyte membrane is insufficient. Further, when it is attempted to provide a through hole in this porous body, there is a problem that the inside of the porous body is remarkably collapsed and the mechanical strength becomes insufficient.

Therefore, an object of the present invention is to provide an electrolyte membrane reinforcing material having high proton conductivity, heat resistance and power generation durability, and excellent in electrolyte resistance, mechanical properties (mechanical strength) and dimensional stability. It is in. Another object of the present invention is to provide an electrolyte membrane suitable for a fuel cell, a solid secondary battery, or the like.

Therefore, as a result of diligent studies to achieve the above object, the present inventors can produce an electrolyte membrane reinforcing material and an electrolyte membrane that can solve the above problems by using a non-woven fabric made of PEEK (polyetheretherketone) fiber. And completed the present invention.

That is, the present invention provides an electrolyte membrane reinforcing material containing a nonwoven fabric made of PEEK fiber.

Further, the electrolyte membrane reinforcing material of the present invention preferably has an average pore diameter of 3 to 280 μm.

Further, the electrolyte membrane reinforcing material of the present invention preferably has a porosity of 15 to 70%.

Further, in the electrolyte membrane reinforcing material of the present invention, it is preferable that the average fiber diameter of the PEEK fiber is 10 μm or less.

Further, in the electrolyte membrane reinforcing material of the present invention, the weight of the nonwoven fabric is preferably 2 to 20 g / m ² .

Further, in the electrolyte membrane reinforcing material of the present invention, the thickness of the nonwoven fabric is preferably 5 to 300 μm.

Further, in the electrolyte membrane reinforcing material of the present invention, the crystallinity of the PEEK fiber is preferably 30% or less.

Further, in the electrolyte membrane reinforcing material of the present invention, it is preferable that the PEEK fiber is a laser molten electrospinning PEEK fiber.

The present invention also provides an electrolyte membrane containing the electrolyte membrane reinforcing material.

Since the electrolyte membrane reinforcing material of the present invention contains PEEK, it has heat resistance and power generation durability at a continuous use temperature of about 250 to 300 ° C., and has excellent electrolyte resistance, mechanical properties (mechanical strength), and dimensional stability. Excellent. Further, since the electrolyte membrane reinforcing material of the present invention contains a non-woven fabric made of PEEK fiber, it has excellent proton conductivity and high power generation performance can be obtained. Since the electrolyte membrane of the present invention contains an electrolyte membrane reinforcing material having the above-mentioned characteristics, when used in a fuel cell, it has high protons or hydroxide ion conductivity, power generation durability, and electrolyte resistance, which lead to high power generation characteristics. In addition to mechanical properties (mechanical strength) and heat resistance, it has impermeable fuel (gas or liquid). Further, when used in an all-solid-state secondary battery, it has high ionic conductivity such as lithium ion, mechanical properties (mechanical strength), safety, and chemical stability.

It is the schematic which shows an example of the manufacturing method of PEEK fiber schematically. It is a schematic diagram of the tailor cone formed in the band-shaped melting part. It is sectional drawing which shows typically an example of the nonwoven fabric manufacturing apparatus which includes the manufacturing method of PEEK fiber.

[Electrolyte membrane reinforcing material]
The electrolyte membrane reinforcing material of the present invention is characterized by using a non-woven fabric made of PEEK fiber. The electrolyte membrane reinforcing material is a sheet-like or felt-like porous body having a large number of communicating pores. In the case of a fuel cell, the average pore diameter of the electrolyte membrane reinforcing material is, for example, 0.01 to 100 μm, preferably 0.05 to 10 μm, more preferably 0.1 to 2 μm, and further preferably 0.1 to 1 μm. .. In the case of an all-solid-state secondary battery, it is, for example, 3 to 280 μm, preferably 5 to 260 μm, more preferably 10 to 240 μm, and even more preferably 20 to 220 μm. When the average pore diameter is in the above range, proton conductivity and lithium ion conductivity are excellent, and high power generation performance and charge / discharge performance can be easily obtained. The average pore diameter can be measured by obtaining the average value of the pores observed using, for example, an electron micrograph.

The porosity of the electrolyte membrane reinforcing material is, for example, 30 to 90%, preferably 40 to 85%, and more preferably 50 to 80%. When the porosity is within the above range, proton conductivity and lithium ion conductivity are excellent, and high power generation performance and charge / discharge performance can be easily obtained. The porosity can be measured by determining the area of pores per unit area observed using electron micrographs.

The thickness of the electrolyte membrane reinforcing material is, for example, about 5 to 300 μm, preferably 5 to 100 μm, more preferably 10 to 90 μm, and further preferably 10 to 80 μm. The basis weight (weight) of the electrolyte membrane reinforcing material is, for example, about 2 to 20 g / m ² , preferably 3 to 15 g / m ² , and more preferably 4 to 10 g / m ² .

The electrolyte membrane reinforcing material of the present invention may include a nonwoven fabric made of PEEK fiber and is not particularly limited, but the content of the nonwoven fabric made of PEEK fiber is preferably, for example, 50% by weight or more, preferably 50% by weight or more, based on the entire electrolyte membrane reinforcing material. Is 70% by weight or more, more preferably 80% by weight or more, still more preferably 90% by weight or more. In addition to the non-woven fabric made of PEEK fiber, other thermoplastic resins, thermosetting resins, metals, ceramics and the like can be contained as long as the effects of the present invention are not impaired.

(PEEK fiber)
The PEEK fiber is preferably a fiber having a small fiber diameter, and the diameter thereof is, for example, 10 μm or less (0.1 to 10 μm), preferably 0.5 to 8 μm, and more preferably 0.7 to 6 μm. Further, the fiber having such a diameter may include minute fibers having a fiber diameter (diameter) of, for example, about 50 to 1000 nm. The diameter of the PEEK fiber can be adjusted by appropriately adjusting various conditions (for example, the thickness of the polymer sheet, the feed rate of the polymer sheet, the laser intensity, etc.) of the PEEK fiber manufacturing method described later. The diameter of the PEEK fiber can be measured using, for example, an electron microscope.

The average fiber diameter (average diameter) of the PEEK fibers as an aggregate is, for example, 10 μm or less (0.1 to 10 μm), preferably 0.5 to 8 μm, and more preferably 0.7 to 6 μm. For the average fiber diameter, for example, a plurality of fiber morphologies (for example, 10) are photographed using a scanning electron microscope, and about 10 fiber diameters per image are arbitrarily measured from a plurality of captured images with image processing software or the like. And it can be calculated by averaging them.

The PEEK fiber has a crystallinity of, for example, 30% or less, preferably 29% or less, and more preferably 28% or less. When the crystallinity is 30% or less, the processability is excellent and the non-woven fabric can be easily molded. The crystallinity can be determined by, for example, an X-ray diffraction method, a DSC (differential scanning calorimetry) measurement, a density method, or the like. The crystallinity was calculated from the amount of heat obtained from DSC measurement by the method described in Examples.

The proportion of PEEK in the PEEK fiber is, for example, 50% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more, still more preferably 90% by weight or more, particularly PEEK fiber, based on the whole PEEK fiber. It preferably consists of PEEK only. Other than PEEK, other thermoplastic resins, additives and the like can be contained. Further, it is preferable that the PEEK fiber is obtained by using the polymer sheet described later as a raw material and the method for producing PEEK fiber described later.

(Non-woven fabric)
The non-woven fabric is made by accumulating the PEEK fibers in a sheet shape or a felt shape. The thickness of the nonwoven fabric is, for example, about 5 to 300 μm, preferably 5 to 100 μm, more preferably 10 to 90 μm, and even more preferably 10 to 80 μm. The basis weight of the nonwoven fabric is, for example, about 2 to 20 g / m ² , preferably 3 to 15 g / m ² , and more preferably 4 to 10 g / m ² . In the non-woven fabric manufacturing method described later, the non-woven fabric is controlled in shape such as fiber diameter, thickness, and basis weight of the non-woven fabric to be manufactured by adjusting the sheet feeding speed, laser intensity, moving speed of the collecting member, and the like. can do.

The content of the PEEK fiber in the nonwoven fabric is, for example, 50% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more, still more preferably 90% by weight or more, based on the entire nonwoven fabric. In addition to PEEK fiber, other thermoplastic resins, thermosetting resins, metals, ceramics and the like can be included as long as the effects of the present invention are not impaired.

[Electrolyte membrane]
The electrolyte membrane of the present invention is not particularly limited as long as it contains the electrolyte membrane reinforcing material, but it is preferable that the pores in the nonwoven fabric made of PEEK fiber are filled (impregnated) with the polymer solid electrolyte or the inorganic solid electrolyte. Polymer solid electrolytes and inorganic solid electrolytes can be used for all-solid secondary batteries, but recently, inorganic solid electrolytes with excellent lithium ion conductivity have been found, and inorganic solid electrolytes can be used. preferable.

The material of the inorganic solid electrolyte is not particularly limited as long as it has ionic conductivity and insulating properties, and examples thereof include sulfide-based solid electrolyte materials and oxide-based solid electrolyte materials. Among these, a sulfide-based solid electrolyte material is preferable. As a result, the interface resistance with the positive electrode active material is further reduced, and an all-solid-state secondary battery having excellent output characteristics can be obtained.

Examples of the sulfide-based solid electrolyte material include Li ₂ SP ₂ S ₅ material, Li ₂ S-Si S ₂ material, Li ₂ S-GeS ₂ material, Li ₂ S-Al ₂ S ₃ material, and Li ₂ S-. SiS ₂ -Li ₃ PO ₄ material, Li ₂ SP _{2 S 5-GeS 2 material, Li 2 S-Li 2 O-P 2 S 5 - SiS 2 material ,} Li ₂ S-GeS ₂ -P ₂ S ₅ -SiS ₂ material, Li ₂ S-SnS ₂ -P ₂ S ₅ -SiS ₂ material and the like can be mentioned. Among these, the Li ₂ SP ₂ S ₅ material is preferable because it has excellent lithium ion conductivity and the manufacturing method is simple. These materials may be used alone or in combination of two or more. Among these, the Li ₂ SP ₂ S ₅ material is preferable because it has excellent lithium ion conductivity and stability that does not cause decomposition in a wide voltage range.

Examples of the polymer solid electrolyte include a fluorine-based electrolyte and a hydrocarbon-based electrolyte. Examples of the fluorine-based electrolyte include a perfluorocarbon sulfonic acid-based polymer, a polytrifluorostyrene sulfonic acid-based polymer, and a perfluorocarbon phosphonic acid-based polymer. As a commercially available product of the perfluorocarbon sulfonic acid polymer, Nafion (registered trademark, manufactured by DuPont) or the like can be used. As the hydrocarbon-based electrolyte, polysulfone, polyethersulfone, polyphenylene oxide, polyphenylene sulfide-based polymer, or the like can be used.

Examples of the method of filling (impregnating) the pores in the non-woven fabric with the polymer solid electrolyte include coating treatment (for example, bar coating treatment, spray coating treatment, dip coating treatment) and the like. The filling amount of the polymer solid electrolyte is, for example, about 10 to 500 parts by weight, preferably 20 to 300 parts by weight, and more preferably 50 to 250 parts by weight with respect to 100 parts by weight of the nonwoven fabric. The filling amount of the polymer solid electrolyte is, for example, 20 to 90% by weight, preferably 30 to 80% by weight, and more preferably 40 to 75% by weight with respect to the entire electrolyte membrane.

The electrolyte membrane of the present invention may be subjected to surface treatment such as corona discharge treatment, ultraviolet irradiation treatment, and plasma treatment for the purpose of facilitating impregnation with the electrolyte liquid. Further, the electrolyte membrane of the present invention may be heat-treated for the purpose of increasing the mechanical strength.

The air permeability of the electrolyte membrane is preferably substantially non-breathable, for example, 5000 s / 100 cc or more, preferably 10000 s / 100 cc or more. The air permeability can be determined by measuring the time (s) through which 100 cc of air permeates using a Gale type densometer based on JIS-P8117. The thickness of the electrolyte membrane is, for example, about 5 to 500 μm, preferably 5 to 150 μm, more preferably 10 to 120 μm, and even more preferably 10 to 100 μm.

[Manufacturing method of electrolyte membrane reinforcing material]
The electrolyte membrane reinforcing material of the present invention is not particularly limited, but can be obtained by producing PEEK fiber and producing a nonwoven fabric formed from PEEK fiber. Hereinafter, a method for producing PEEK fiber and a method for producing a nonwoven fabric formed from PEEK fiber will be described.

(Manufacturing method of PEEK fiber)
The PEEK fiber is not particularly limited, but can be produced by using a laser melting electrospinning method. That is, the PEEK fiber is preferably a laser molten electrospinning PEEK fiber. In the method for producing PEEK fiber, the polymer sheet is irradiated with a band-shaped laser beam to linearly heat and melt the end portion of the polymer sheet, and at the same time, a potential difference is generated between the melted band-shaped melted portion and the fiber collecting plate. By providing, a needle-shaped protruding portion is formed in the strip-shaped melting portion, and the fibers discharged from the needle-shaped protruding portion are allowed to fly toward the fiber collecting plate, and the fiber collecting plate or the strip-shaped melting portion is provided. PEEK fibers are obtained by collecting on a collecting member interposed between the fiber collecting plates.

The laser melting electrospinning method will be described with reference to the drawings. FIG. 1 is a schematic view schematically showing an example of a method for producing PEEK fiber.

In the PEEK fiber manufacturing method, as shown in FIG. 1, an optical path adjusting means including a beam expander, a homogenizer 2, a collimation lens 3, and a cylindrical lens group 4 emits a laser beam having a spot-like cross section emitted from a laser source 1. After converting to a band-shaped laser beam 5 having a linear cross section, the edge of the polymer sheet 6 held by the holding member 7 is irradiated to form a band-shaped molten portion 6a, and the high voltage generator 10 is used to form the band-shaped molten portion 6a. A voltage is applied to generate a potential difference between the band-shaped melting portion 6a and the fiber collecting plate 8 disposed under the polymer sheet 6. Further, the temperature of the band-shaped melting portion 6a can be observed by the thermography 9, and the conditions such as the voltage and the laser beam to be irradiated can be optimized.

In the example shown in FIG. 1, the holding member 7 that holds the polymer sheet 6 also functions as an electrode, and when a voltage is applied to the holding member 7 by the high voltage generator 10, the polymer sheet 6 is used. A charge is applied to the band-shaped molten portion 6a formed by the irradiation of the band-shaped laser light 5. The fiber collecting plate 8 has a surface electrical resistance value equivalent to that of metal. The shape may be, for example, a plate shape, a roller shape, a belt shape, a net shape, a saw shape, a wavy shape, a needle shape, a linear shape, or the like.

FIG. 2 is a schematic view of a tailor cone formed in the band-shaped melting portion 6a. As shown in FIG. 2, a plurality of needle-shaped protrusions (tailor cones) 6b are gradually formed on the surface of the band-shaped molten portion 6a to which the electric charge is applied by collecting and repelling the electric charge, and the repulsive force of the electric charge is generated. When the surface tension is exceeded, the molten polymer sheet is discharged as fibers from the tip of the tailor cone toward the fiber collecting plate 8 by electrostatic attraction, that is, fibers are formed from the needle-shaped protrusion 6b and the fibers are collected. Fly in 8 directions on the board. As a result, the stretched fibers are collected by the fiber collecting plate 8. Further, when the collecting member is placed on the fiber collecting plate 8, the fibers are collected on the collecting member. That is, in the method for producing PEEK fiber, the fiber collecting plate itself may be used as a member for collecting fibers, or the collecting member may be placed on the fiber collecting plate separately from the fiber collecting plate.

The number of the tailor cones (interval between the tailor cones) shown in FIG. 2 can be adjusted by appropriately changing the thickness of the polymer sheet 6. The development of the tailor cone means that the height of the tailor cone (h in FIG. 2) increases.

The number of the tailor cones is not particularly limited, but is preferably 1 to 100, more preferably 1 to 50, still more preferably 2 to 10 per 2 cm in the width direction of the heated and melted portion of the polymer sheet. be. When the number of tailor cones is 1 to 100 per 2 cm in the width direction, the fiber proportion does not decrease due to electrical repulsion between tailor cones, and an appropriate production amount can be secured. can.

Examples of the laser generation source include a YAG laser, a carbon dioxide (CO ₂ ) laser, an argon laser, an excimer laser, a helium-cadmium laser, and the like. Among these, a carbon dioxide laser is preferable because of its high power efficiency and high meltability of PEEK. The wavelength of the laser beam is preferably 200 nm to 20 μm, more preferably 500 nm to 18 μm, and even more preferably 5 to 15 μm.

Further, in the method for producing PEEK fiber, when a band-shaped laser beam is irradiated, the thickness of the laser beam is preferably 0.5 to 10 mm. If the thickness of the laser beam is less than 0.5 mm, it may be difficult to form a tailor cone, and if it exceeds 10 mm, the melt residence time becomes long and the material may be deteriorated.

Further, the output of the laser beam may be controlled within a range in which the temperature of the strip-shaped molten portion is equal to or higher than the melting point of the polymer sheet and is equal to or lower than the ignition point of the polymer sheet. Higher is preferable from the viewpoint of reducing the diameter of the. The specific output of the laser beam can be appropriately selected depending on the physical properties (melting point, LOI value (limiting oxygen index)) and shape of the polymer sheet to be used, the feed rate of the polymer sheet, etc., but is preferably 5 to 100 W. It is about / 13 cm, more preferably 20 to 60 W / 13 cm, and further preferably 30 to 50 W / 13 cm. The output of the laser beam is the output of the spot beam emitted from the laser source.

The temperature of the strip-shaped melting portion is not particularly limited as long as it is at least the melting point of PEEK (334 ° C.) and below the ignition point, but is usually about 350 to 600 ° C., preferably 380 to 500 ° C. ..

In the PEEK fiber manufacturing method shown in FIG. 1, the laser beam irradiates the strip-shaped molten portion (end portion) of the polymer sheet from only one direction, but for example, the laser beam is emitted from two directions through a reflection mirror. The band-shaped molten portion (edge portion) of the polymer sheet may be irradiated. This is because even if the polymer sheet is thick, the end portion thereof can be melted more uniformly.

In the method for producing PEEK fiber, the potential difference generated between the end portion of the polymer sheet and the collecting member is preferably a high voltage within a range that does not discharge, and the required fiber diameter (diameter) and electrode. It can be appropriately selected depending on the distance between the fiber and the collecting member, the irradiation amount of the laser beam, etc., but is usually about 0.1 to 30 kV / cm, preferably 0.5 to 20 kV / cm, and more preferably 1 to 10 kV / cm. Is.

The method of applying a voltage to the molten portion of the polymer sheet may be a direct application method in which the irradiation portion of the laser beam (the strip-shaped molten portion of the polymer sheet) and the electrode portion for applying a charge are matched. , The device can be easily manufactured, the laser light can be effectively converted into heat energy, the reflection direction of the laser light can be easily controlled, and the safety is high. An indirect application method (particularly, a method of providing a laser beam irradiation portion on the downstream side in the feeding direction of the polymer sheet) is preferable. In particular, in the above manufacturing method, the polymer sheet is irradiated with the band-shaped laser light on the downstream side of the electrode portion, and the distance between the electrode portion and the laser light irradiation portion (for example, the lower end of the electrode portion and the upper side of the band-shaped laser light). It is preferable to adjust the distance from the outer edge to a specific range (for example, about 10 mm or less). This distance can be selected according to the conductivity, thermal conductivity, glass transition point, laser beam irradiation amount, etc. of the polymer sheet, and is preferably 0.5 to 10 mm, more preferably 1 to 8 mm, still more preferably 1. .5 to 7 mm, particularly preferably 2 to 5 mm. When the distance between the two is within this range, the molecular motion of the resin in the laser beam irradiation portion is enhanced, and a sufficient charge can be applied to the molten resin, so that the productivity can be improved.

The distance between the end portion of the polymer sheet (the tip end portion of the tailor cone) and the collection member is not particularly limited, and is usually 5 mm or more, but in order to efficiently produce a fiber having a small diameter, it is necessary. It is preferably 10 to 300 mm, more preferably 15 to 200 mm, still more preferably 50 to 150 mm, and particularly preferably 80 to 120 mm.

When the polymer sheet is continuously fed, the feeding speed is preferably 2 to 20 mm / min, more preferably 3 to 15 mm / min, and even more preferably 4 to 10 mm / min. If the speed is increased, the productivity is increased, but if the speed is too high, the polymer sheet in the laser beam irradiation portion is not sufficiently melted, so that it is difficult to manufacture the fiber. On the other hand, if the speed is slow, the polymer sheet will decompose and the productivity will decrease.

The polymer sheet preferably has a crystallinity of 25% or less, more preferably 20% or less, still more preferably 15% or less. When the crystallinity is 25% or less, PEEK fiber having a low crystallinity can be obtained. The crystallinity of the polymer sheet can be determined by the same method as the crystallinity of PEEK fiber.

The polymer sheet preferably has a low melt viscosity because it is easy to obtain fibers having a small fiber diameter, and the melt viscosity at a shear rate (shear velocity) of 121.6 (1 / s) measured at 400 ° C. is high. It is preferably 800 Pa · s or less (50 to 800 Pa · s), more preferably 600 Pa · s or less, and further preferably 400 Pa · s or less. The melt viscosity can be determined by the method described in Examples using a capillary leometer (trade name "Capillary Graph 1D", manufactured by Toyo Seiki Seisakusho Co., Ltd.). The shear rate (shear velocity) can also be measured using a capillary leometer.

The polymer sheet can be produced, for example, by heating and melting chip-shaped PEEK with a T-die extruder or the like to form a sheet. As the chip-shaped PEEK, a commercially available product can be used, and a trade name “VESTAKEP 1000G” (manufactured by Daicel Evonik Industries, Ltd.) or the like can be preferably used. The heating temperature of the T-die extruder may be equal to or higher than the melting point of PEEK, and is, for example, 350 to 400 ° C.

The polymer sheet contains various additives used for fibers, such as infrared absorbers, stabilizers (antioxidants, ultraviolet absorbers, heat stabilizers, etc.), flame retardants, antistatic agents, colorants, and fillers. , Lubricants, antibacterial agents, insect and tick repellents, fungicides, matting agents, heat storage agents, fragrances, optical brighteners, wetting agents, plasticizers, thickeners, dispersants, foaming agents, surfactants, etc. It may be contained. These additives can be blended alone or in combination of two or more.

Among these additives, it is preferable to use a surfactant. When a high voltage is applied to the polymer sheet to inject the electric charge, the polymer sheet has high electrical insulation and it is difficult to inject the electric charge into the heat-melted portion where the electric resistance becomes low. However, when a surfactant is used, the electrical resistance on the surface of the polymer sheet having a large electrical insulation property is reduced, and a sufficient charge can be injected to the heat-melted portion. Further, the addition of a surfactant or the like is effective in preventing phase separation when the sheet is composed of a plurality of components when a high voltage is applied to the polymer sheet to inject charges.

Each of these additives can be used in a ratio of 50 parts by weight or less with respect to 100 parts by weight of the resin constituting the polymer sheet, preferably 0.01 to 30 parts by weight, and more preferably 0.1 to 5 parts by weight. It is the ratio of parts by weight.

The thickness of the polymer sheet is preferably 0.01 to 10 mm, more preferably 0.05 to 5.0 mm. When the thickness is in the above range, the PEEK fiber described later can be easily manufactured.

Further, in the method for producing PEEK fiber, the space between the end portion of the polymer sheet and the collecting member may have an inert gas atmosphere. By making this space an inert gas atmosphere, ignition of fibers can be suppressed, so that the output of laser light can be increased. Examples of the inert gas include nitrogen gas, helium gas, argon gas, carbon dioxide gas and the like. Of these, nitrogen gas is usually used. Further, by using the above-mentioned inert gas, the oxidation reaction in the band-shaped molten portion can be suppressed.

Further, the space may be heated. The diameter of the fiber obtained by heating can be reduced. That is, by heating the air in the space or the inert gas, the rapid temperature drop of the fibers being formed can be suppressed, thereby promoting the elongation or stretching of the fibers and obtaining finer fibers. Is to be done. Examples of the heating method include a method using a heater (halogen heater and the like), a method of irradiating a laser beam, and the like. The heating temperature can be selected from, for example, a temperature range of 50 ° C. or higher to less than the ignition point of the resin, but from the viewpoint of spinnability, a temperature lower than the melting point of PEEK is preferable.

(Manufacturing method of non-woven fabric formed from PEEK fiber)
Next, an example of a method for producing a nonwoven fabric formed from PEEK fiber will be described. In the following method for producing a nonwoven fabric formed from PEEK fiber, in the above-mentioned method for producing PEEK fiber, the PEEK fiber is produced while moving the collection position of the fibers flying in the direction of the fiber collecting plate over time. The method is continuously carried out and these are accumulated in a sheet shape to obtain a non-woven fabric. A nonwoven fabric formed from PEEK fibers may be produced by the method shown below, or the PEEK fibers obtained by the method for producing PEEK fibers may be used as a nonwoven fabric by another method.

Here, as a method of moving the collection position of the fibers flying in the direction of the fiber collection plate over time, for example, (1) a collection member (when the fiber collection plate itself functions as a collection member, the fiber How to move the collection plate), (2) How to move the holding position of the polymer sheet, (3) Mechanically, magnetically or electrically to the flying fibers from the tailor cone to the collection member. A method of applying a force, for example, a method of blowing air onto a flying fiber, a method of (4) selectively combining the above methods (1) to (3), and the like can be used.

Among these, the method (1) above, that is, the method of moving the collecting member, is easy to simplify the configuration of the apparatus and control the shape (thickness, basis weight, etc.) of the non-woven fabric to be manufactured. desirable. Hereinafter, the method for producing a nonwoven fabric formed from PEEK fiber will be described in detail by taking the case of using the method (1) above as an example.

In the method for producing a nonwoven fabric formed from PEEK fiber using the method (1) above, in the method for producing PEEK fiber shown in FIG. 1, a collecting member is placed on the fiber collecting plate 8. While moving the collecting member in a direction perpendicular to the width method of the polymer sheet 6 (right direction or left direction in the figure), the PEEK fiber manufacturing method is continuously performed. Here, the moving speed of the collecting member may be constant, may change with time, and may be repeatedly moved and stopped. In order to continuously perform the PEEK fiber manufacturing method, as described above, the polymer sheet 6 is placed on the fiber collecting plate 8 side (collecting member side) as the fiber manufacturing process progresses. It should be sent out continuously. The speed (feeding speed) of continuously feeding the polymer sheet is as described in the PEEK fiber manufacturing method.

Further, the moving speed of the collecting member on the fiber collecting plate 8 is not particularly limited and may be appropriately determined in consideration of the basis weight of the fiber sheet to be manufactured, but is usually about 10 to 2000 mm / min. For example, when the feed rate of the polymer sheet having a basis weight of 1000 g / m ² is 0.5 mm / min, by setting the moving speed of the collecting member to about 1000 mm / min, the basis weight is about 0.5 g / m ² . Nonwoven fabrics can be continuously produced.

FIG. 3 is a cross-sectional view schematically showing an example of a nonwoven fabric manufacturing apparatus including the PEEK fiber manufacturing method shown in FIG. 1 described above. The device (non-woven electrode manufacturing device) shown in FIG. 3 is a laser generation source 11, an optical path adjusting member 12, a polymer sheet feeding device 13 capable of continuously feeding a polymer sheet 6, and a holding device for holding the polymer sheet 6. Through the member 16, the electrode 17 that applies an electric charge to the polymer sheet 6, the collecting member 22 for collecting fibers, the band-shaped melting portion (end) 6a of the electrode 17 and the polymer sheet 6, and the collecting member 22. High voltage generators 20a and 20b that apply a voltage to the electrodes 17 and the fiber collecting plates 14, respectively, and the housing 23 in which the fiber collecting plates 14 and the heating device 15 are arranged so as to face each other. A pulley 21 for moving the collecting member 22 is provided. As described above, the optical path adjusting member 12 is an assembly of optical components, and is composed of a beam expander and a homogenizer 2, a collimation lens 3, a cylindrical lens group 4, and the like shown in FIG.

In FIG. 3, the band-shaped laser beam 5 emitted from the laser generation source 11 and via the optical path adjusting member 12 is introduced into the housing 23 and irradiated to the band-shaped melting portion (end portion) 6a of the polymer sheet 6. .. A polymer sheet feeding device 13 provided with a motor and a mechanism for converting the rotational motion of the motor into linear motion is attached to the upper part of the housing 23, and the polymer sheet 6 is the polymer sheet feeding device 13. It will be attached to the housing 23 and continuously sent out into the housing 23. On the other hand, the lower portion of the polymer sheet 6 is held by the holding member 16 to which the electrode 17 is attached. Since the polymer sheet 6 and the electrode 17 are always in contact with each other, when a voltage is applied to the electrode 17, the polymer sheet 6 is charged.

The fiber collecting plate 14 that functions as an electrode paired with the electrode 17 is arranged at a position facing each other via the band-shaped melting portion (end portion) 6a of the polymer sheet 6 and the collecting member 22. Therefore, when a voltage is applied to the electrode 17 and the fiber collecting plate 14, a potential difference is generated between the band-shaped melting portion (end portion) 6a of the polymer sheet 6 and the collecting member 22. The voltage is applied to the electrodes 17 and the fiber collecting plate 14 by the high voltage generators 20a and 20b connected to the electrodes 17 and the fiber collecting plate 14, respectively. In this nonwoven fabric manufacturing apparatus, the electrode 17 is a positive electrode and the fiber collecting plate 14 is a negative electrode, but the opposite is also possible. The collecting member 22 is a belt conveyor composed of a pulley 21 and a conveyor belt, and the conveyor belt itself corresponds to the collecting member 22. Therefore, as the pulley 21 is driven, the collecting member 22 (conveyor belt) moves in a predetermined direction (for example, in the right direction in the drawing).

The non-woven fabric manufacturing apparatus shown in FIG. 3 includes a heating device 15 and can heat the stretched fibers by being discharged from the strip-shaped melting portion (end portion) 6a of the polymer sheet 6 toward the collecting member 22. .. Further, a laser light absorption plate 19 and a heat absorption plate 18 are provided in the housing 23.

In the non-woven fabric manufacturing apparatus shown in FIG. 3, the polymer sheet 6 is fed by the polymer sheet feeding device 13 and the holding member 16 in a state where a voltage is applied to both the electrode 17 and the fiber collecting plate 14. By irradiating the band-shaped melting portion (end) 6a of the band-shaped melting portion (end) 6a with a band-shaped laser beam 5, a tailor cone is formed on the band-shaped melting portion (end) 6a of the polymer sheet 6 as described above. The fibers are ejected and fly to the fiber collecting plate 14, and as a result, the elongated fibers are collected by the collecting member 22. Then, the non-woven fabric can be manufactured on the collecting member 22 by continuously feeding the polymer sheet 6 (continuously discharging the fibers) and moving the collecting member 22.

In the nonwoven fabric manufacturing apparatus shown in FIG. 3, the collecting member 22 is a sheet-shaped member. In this device, the collecting member 22 is not particularly limited as long as it is in the form of a sheet, but is paper, a film, various woven fabrics, a non-woven fabric, a mesh, or the like. Further, the collecting member may be a metal or a sheet or a belt having a surface electric resistance value equivalent to that of the metal.

In the non-woven fabric manufacturing apparatus shown in FIG. 3, the material of the electrode 17 and the fiber collecting plate 14 may be a conductive material (usually a metal component), for example, a Group 6 element such as chromium and a tenth element such as platinum. Metal units and alloys (aluminum alloys, stainless alloys, etc.) such as group elements, group 11 elements such as copper and silver, group 12 elements such as zinc, group 13 elements such as aluminum, or compounds containing these metals. (Metal oxides such as silver oxide and aluminum oxide) and the like can be mentioned. These metal components can be used alone or in combination of two or more. Of these metal components, copper, silver, aluminum, stainless alloys and the like are particularly preferable. The shape of the fiber collecting plate 14 is not particularly limited, and examples thereof include a plate shape, a roller shape, a belt shape, a net shape, a saw shape, a wavy shape, a needle shape, and a linear shape. Of these shapes, a plate shape and a roller shape are particularly preferable. Examples of the laser light absorbing plate 19 include a metal coated with a black body, a porous ceramic, and the like. Examples of the heat absorbing plate 18 include black ceramics and the like. By using such an apparatus, the nonwoven fabric can be efficiently manufactured.

The electrolyte membrane reinforcing material of the present invention is manufactured through a step (pressing step) in which a nonwoven fabric formed from PEEK fiber is compression-molded using, for example, a die, if necessary, in addition to the above-mentioned manufacturing method. But it may be. Further, the electrolyte membrane reinforcing material may be one in which a plurality of the nonwoven fabrics or the nonwoven fabrics other than the above are laminated and compression molded (pressed) to be integrated. Further, the electrolyte membrane of the present invention can be produced by filling (impregnating) the pores of the electrolyte membrane reinforcing material obtained by the above method with a polymer solid electrolyte, an inorganic solid electrolyte, or the like.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1
(Preparation of polymer sheet)
A chip-shaped sample of PEEK [manufactured by Daicel Ebonic, trade name "VESTAKEE P 1000G"] is subjected to a lab-plast mill T-die extrusion molding device (manufactured by Toyo Seiki Seisakusho Co., Ltd.) with a die width of 150 mm and a lip width of 0.4 mm. Using a T-die, extrude into a sheet at an extrusion temperature of 345 to 360 ° C., take up a polymer sheet with a take-up roll temperature of 140 ° C. and a take-up speed of 1.0 to 2.0 m / min, and have a thickness of 0.1 mm. Was produced.
The melt viscosity (400 ° C.) of the produced polymer sheet measured by the following method was 151 Pa · s, and the crystallinity of the polymer sheet was 12.7%. The crystallinity of the polymer sheet was determined by the same method as the crystallinity of the PEEK fiber forming the following nonwoven fabric.

Next, using the polymer sheet produced by the above method, a nonwoven fabric formed from PEEK fiber was produced by the following method.

(Manufacturing of non-woven fabric formed from PEEK fiber)
A non-woven fabric formed from PEEK fiber was manufactured by the non-woven fabric manufacturing apparatus outlined in FIG.
As the laser generation source 11 of the apparatus shown in FIG. 3, a CO ₂ laser (manufactured by Universal Laser Systems, Inc., wavelength 10.6 μm, output 45 W, air-cooled type, beam diameter φ4 mm) was used. As the optical path adjusting member 12 of the apparatus shown in FIG. 3, a beam expander with a magnification of 2.5 times, a homogenizer (incident beam diameter φ12 mm (design value), emission beam diameter φ12 mm (design value)), and a collation lens (incident). A beam diameter of φ12 mm (design value), an emission beam diameter of φ12 mm (design value)), a cylindrical lens (planar concave lens, f-30 mm), and a cylindrical lens (plano-convex lens, f-300 mm) are arranged at predetermined positions in this order. I used the one that I did. Through these optical path adjusting members, the spot-shaped laser light is converted into a strip-shaped laser beam 5 having a width of about 150 mm and a thickness of about 1.4 mm, and the strip-shaped molten portion (end) 6a of the polymer sheet 6 is irradiated. did. At this time, the output of the laser beam was 61 W / 13 cm, the feed rate of the polymer sheet was 6 mm / min, and the potential difference between the electrode 17 and the fiber collecting plate 14 was 6 kV / cm.
As a result, a nonwoven fabric formed from PEEK fibers having an average fiber diameter (diameter) of 0.7 μm was obtained. The crystallinity of the PEEK fiber forming the non-woven fabric by the following measuring method was 24.0%. The non-woven fabric produced above was used as an electrolyte membrane reinforcing material. The average pore diameter of the electrolyte membrane reinforcing material was 200 μm, and the porosity was 60%.

Example 2
(Manufacturing of electrolyte membrane reinforcement)
The non-woven fabric obtained from the non-woven fabric formed from the PEEK fiber of Example 1 is bundled and inserted into a mold (width 10 mm, length 30 mm, thickness 1 mm) so that the thickness after molding is 40 μm, and the mold is closed. Then, it was heated at 120 ° C. for 30 seconds and pressed (compression molding) at 0.5 MPa to obtain an electrolyte reinforcing material. The average pore diameter of the electrolyte membrane reinforcing material was 100 μm, and the porosity was 70%.

Example 3
(Manufacturing of electrolyte membrane)
An electrolyte membrane was produced using the electrolyte membrane reinforcing material obtained in Example 2 above. A perfluorocarbon-based sulfonic acid resin solution (Dupont's "Nafion (trade name)" solution, 5% by mass concentration) was concentrated to a concentration of 15% by mass with an evaporator, and the above-mentioned electrolyte membrane reinforcing material was immersed therein to make a surplus. The concentration solution was wiped off with a bar and then dried to obtain an electrolyte membrane in which the perfluorocarbon-based sulfonic acid resin was filled in the pores of the electrolyte membrane reinforcing material.
Drying was carried out in a hot air furnace at 80 ° C. for 30 minutes, and the filling amount of the perfluorocarbon-based sulfonic acid resin was 70% by weight of the entire electrolyte membrane.

(Measuring method of melt viscosity (400 ° C) of polymer sheet)
The melt viscosity of the polymer sheet at a shear rate (shear velocity) of 121.6 (1 / s) measured at 400 ° C. was reported to a capillary leometer (trade name "Capillary Graph 1D", manufactured by Toyo Seiki Seisakusho Co., Ltd.). The measurement was performed using a jig having a capillary diameter of 1 mm and a length of 10 mm.

(Measuring method of crystallinity of PEEK fiber forming non-woven fabric)
The crystallinity of the PEEK fiber forming the non-woven fabric was calculated from the amount of heat obtained from the DSC measurement.
DSC measurement is performed using a differential scanning calorimeter (DSC-Q2000 / TA), alumina as the reference material, a nitrogen atmosphere, a temperature range of 0 to 420 ° C, and a temperature rise rate of 20 ° C / min. rice field.
From the calorific value obtained by DSC measurement, the crystallinity was determined using the following formula.
Crystallinity (%) = {(heat of fusion of sample [J / g])-(heat of fusion of sample [J / g])} / heat of fusion of perfect crystal (130 [J / g]) × 100

(Measurement of average pore diameter of electrolyte membrane reinforcing material)
With respect to the electrolyte membrane reinforcing material of Example 1 above, a cross section of the electrolyte membrane reinforcing material is cut out, the area of any 30 or more pores is measured from an electron micrograph of the cross section, and the average value is the average pore area S. I made it _ave . Assuming that the pores are perfect circles, the value converted from the average pore area to the pore diameter using the following formula was taken as the average pore diameter. Where π represents pi.
Average pore diameter [μm] = 2 ・ ( _Save / π) ^1/2

(Measurement of porosity of electrolyte membrane reinforcement)
For the electrolyte membrane reinforcing material of Example 1 above, the porosity of the electrolyte membrane reinforcing material was calculated from the following formula.
A part or all of the electrolyte membrane reinforcing material was cut out, and the volume and weight thereof were measured.
In the following formula, V indicates the volume of the electrolyte membrane reinforcing material [cm ³ ], W indicates the weight of the electrolyte membrane reinforcing material [g], and ρ indicates the density [g / cm ³ ] (the density of PEEK is 1.27).
Porosity [%] = 100-100 ・ W / (ρ ・ V)

1 Laser source 2 Beam expander and homogenizer 3 Collimation lens 4 Cylindrical lens group 5 Band-shaped laser light 6 Polymer sheet 6a Band-shaped melting part 6b Needle-shaped protrusion 7 Holding member 8 Fiber collection plate 9 Thermography 10 High voltage generator 11 Laser source 12 Optical path adjustment member 13 Polymer sheet feeder 14 Fiber collection plate 15 Heating device 16 Holding member 17 Electrode 18 Heat absorption plate 19 Laser light absorption plate 20a High voltage generator 20b High voltage generator 21 Pulley 22 Collection Member 23 Housing h Tailor cone height w Width direction

Claims (6)

The band-shaped melting is performed by irradiating the polymer sheet with a band-shaped laser beam to linearly heat and melt the end portion of the polymer sheet, and by providing a potential difference between the melted band-shaped melting part and the fiber collecting plate. A needle-shaped protrusion is formed in the portion, and the fibers discharged from the needle-shaped protrusion are allowed to fly toward the fiber collection plate, and are interposed on the collection member interposed between the band-shaped melting portion and the fiber collection plate. By collecting PEEK fibers and accumulating them in a sheet shape while moving the collection position over time, a non-woven fabric made of PEEK fibers is obtained, and the obtained non-woven fabric made of PEEK fibers is compression-molded to obtain an electrolyte. A method for manufacturing a film reinforcing material, wherein the electrolyte film reinforcing material has a grain size of 2 to 10 g / m ² and a thickness of 10 to 100 μm. The method for producing an electrolyte membrane reinforcing material according to claim 1, wherein the average pore diameter calculated by the following formula is 3 to 280 μm.
Average pore diameter [μm] = 2 ・ (Save / π) ^1/2
A cross section of the electrolyte membrane reinforcing material is cut out, the area of any 30 or more pores is measured from an electron micrograph of the cross section, and it is assumed that the pores are perfect circles. Convert to pore diameter The method for producing an electrolyte membrane reinforcing material according to claim 1 or 2, wherein the porosity calculated by the following formula is 15 to 70%.
Porosity [%] = 100-100 ・ W / (ρ ・ V)
V indicates the volume of the electrolyte membrane reinforcing material [cm ³ ], W indicates the weight of the electrolyte membrane reinforcing material [g], and ρ indicates the density [g / cm ³ ]. The method for producing an electrolyte membrane reinforcing material according to any one of claims 1 to 3, wherein the average fiber diameter of the PEEK fiber is 10 μm or less.
The method for producing an electrolyte membrane reinforcing material according to any one of claims 1 to 4, wherein the PEEK fiber has a crystallinity of 30% or less.
An electrolyte membrane reinforcing material is obtained by the production method according to any one of claims 1 to 5, and the pores of the obtained electrolyte reinforcing material are filled with a polymer solid electrolyte or an inorganic solid electrolyte to produce an electrolyte membrane. A method for manufacturing an electrolyte membrane.

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