JP2020068089A - Bipolar plate for redox flow cell and manufacturing method thereof - Google Patents

Bipolar plate for redox flow cell and manufacturing method thereof Download PDF

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JP2020068089A
JP2020068089A JP2018199324A JP2018199324A JP2020068089A JP 2020068089 A JP2020068089 A JP 2020068089A JP 2018199324 A JP2018199324 A JP 2018199324A JP 2018199324 A JP2018199324 A JP 2018199324A JP 2020068089 A JP2020068089 A JP 2020068089A
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resin
redox flow
fiber
conductive material
bipolar plate
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昭紘 小泉
Akihiro Koizumi
昭紘 小泉
鈴木　勤
Tsutomu Suzuki
勤 鈴木
岡田　晃
Akira Okada
晃 岡田
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Shin Etsu Polymer Co Ltd
Shin Etsu Chemical Co Ltd
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Abstract

To provide a bipolar plate for redox flow cell capable of improving durability against electrolyte, by improving conductivity while preventing occurrence of breakdown or uneven thickness, and to provide a manufacturing method thereof.SOLUTION: In a bipolar plate 1 for redox flow cell where a resin composition 3 is sandwiched between a pair of composite sheets 2 facing each other, each composite sheet 2 contains at least fiber resin containing polyolefin resin fiber, and a conductive material having conductivity more excellent than that of the fiber resin, where the conductive material contains a particulate conductive material and a fibrous conductive material, the resin composition 3 contains a low fusion point resin having a fusion point lower than that of the fiber resin of the composite sheet 2 by 5°C or more and equal to or higher than the operation temperature of the redox flow cell, and a particle-containing conductive material having at least the particulate conductive material, and the pair of composite sheets 2 and the resin composition 3 are fused and integrated.SELECTED DRAWING: Figure 1

Description

本発明は、バナジウム等のイオンの酸化還元反応を利用して充放電するレドックスフロー電池のレドックスフロー電池用双極板及びその製造方法に関するものである。   TECHNICAL FIELD The present invention relates to a bipolar plate for a redox flow battery of a redox flow battery, which is charged and discharged by utilizing an oxidation-reduction reaction of ions such as vanadium, and a manufacturing method thereof.

レドックスフロー電池は、正極液、負極液と種別される電解液中のバナジウム等のイオンの価数の変化（酸化還元反応）を利用した電力貯蔵用の二次電池であり、安全性が高く、しかも、長寿命であるという特徴を有している（特許文献１、２参照）。このレドックスフロー電池は、一般的に、複数のセルを備え、各セルには、隔膜の両側に多孔質電極（正電極、負電極）と双極板とを備えたフレームが存在しており、正極室には正電液を、負極室には負電液をそれぞれ充分に循環させることにより、電池を反応させる。   A redox flow battery is a secondary battery for power storage that uses a change in the valence of an ion such as vanadium (a redox reaction) in an electrolytic solution classified as a positive electrode solution or a negative electrode solution, and has high safety. Moreover, it has a feature that it has a long life (see Patent Documents 1 and 2). This redox flow battery generally comprises a plurality of cells, and each cell has a frame provided with a porous electrode (positive electrode, negative electrode) and a bipolar plate on both sides of a diaphragm, and a positive electrode is provided. The battery is made to react by sufficiently circulating positive electrode liquid in the chamber and negative electrode liquid in the negative electrode chamber.

これらを隔てる双極板には、レドックスフロー電池の内部抵抗を小さくするための高い導電性の他、電流は流すが電解液を通さない、酸性の電解液に対して劣化しない等の高い機械的強度を有することが要求される。特許文献１には、優れた導電性や機械的強度を得るため、熱可塑性樹脂、黒鉛及びケッチェンブラックから選ばれる炭素質材料、並びにカーボンナノチューブを含有し、これらを複合した複合導電材料からなる双極板であり、熱可塑性樹脂１００質量部に対し、炭素質材料の含有量を２０〜１５０質量部、カーボンナノチューブの含有量を１〜１０質量部としたレドックスフロー電池用双極板が開示されている。   The bipolar plate that separates them has high electrical conductivity to reduce the internal resistance of the redox flow battery, as well as high mechanical strength such as allowing current to flow but not allowing electrolyte to pass, and not deteriorating against acidic electrolyte. Required to have. In Patent Document 1, in order to obtain excellent conductivity and mechanical strength, a carbonaceous material selected from a thermoplastic resin, graphite and Ketjen black, and a composite conductive material containing carbon nanotubes and compounding them Disclosed is a bipolar plate for a redox flow battery, wherein the content of the carbonaceous material is 20 to 150 parts by mass and the content of the carbon nanotubes is 1 to 10 parts by mass with respect to 100 parts by mass of the thermoplastic resin. There is.

しかしながら、特許文献１のレドックスフロー電池用双極板は、所定の効果が得られるものの、熱可塑性樹脂中に黒鉛やカーボンナノチューブが単に分散するに止まるので、黒鉛間のつながりに乏しく、導電性の向上を図ることができない。これでは、さらなる高導電性を求める近年の市場の要求に応えることは非常に困難である。また、近年のレドックスフロー電池用双極板には、高い導電性の他、薄型化、曲げても割れない柔軟性、硫酸バナジウム水溶液に対しても劣化しない特性等も要求されているが、これらの実現は容易ではない。   However, the bipolar plate for a redox flow battery of Patent Document 1 has a predetermined effect, but since graphite and carbon nanotubes are merely dispersed in the thermoplastic resin, the connection between the graphites is poor and the conductivity is improved. Can't plan. This makes it very difficult to meet the recent market demand for higher conductivity. In addition, in recent years, a bipolar plate for a redox flow battery is required to have high conductivity, thinness, flexibility that does not break even when bent, and characteristics that it does not deteriorate even in an aqueous solution of vanadium sulfate. Realization is not easy.

そこで、本発明者等は、係る点に鑑み、繊維樹脂１５〜４０質量部と、この繊維樹脂よりも導電性に優れる導電材８５〜６０質量部とを備えて成形され、繊維樹脂が少なくとも平均繊維長１〜８０ｍｍポリプロピレン繊維系を含み、導電材が粒子状導電材と繊維状導電材の少なくともいずれか一方を含むレドックスフロー電池用双極板を開発し、提案している。   Then, in view of this point, the inventors of the present invention are provided with 15 to 40 parts by mass of the fiber resin and 85 to 60 parts by mass of a conductive material having higher conductivity than the fiber resin, and the fiber resin is at least average. A bipolar plate for a redox flow battery has been developed and proposed, which includes a polypropylene fiber system having a fiber length of 1 to 80 mm and the conductive material includes at least one of a particulate conductive material and a fibrous conductive material.

特開２０１１‐２２８０５９号公報JP, 2011-228059, A 特許第６２６５５５５号公報Japanese Patent No. 6265555

本発明者等が開発し、提案したレドックスフロー電池用双極板は、実用上、優れた効果が期待できるが、導電性がさらに向上すれば、レドックスフロー電池の性能向上に大いに貢献することができる。導電性の向上には、導電材のさらなる添加が考えられるが、例えば特許文献１の技術に導電材を単に添加すると、成形体が損傷したり、厚みムラが生じやすくなるという大きな問題が新たに生じることとなる。さらに、硫酸バナジウム等の電解液に浸漬した環境下では、膨潤が生じ、レドックスフロー電池用双極板の性能を損なうおそれが考えられる。   The bipolar plate for a redox flow battery developed and proposed by the present inventors can be expected to have an excellent effect in practical use, but if the conductivity is further improved, it can greatly contribute to the performance improvement of the redox flow battery. . To improve the conductivity, further addition of a conductive material can be considered. For example, if the conductive material is simply added to the technique of Patent Document 1, there is a new problem that the molded body is easily damaged or uneven thickness is more likely to occur. Will occur. Furthermore, under the environment of being immersed in an electrolytic solution such as vanadium sulfate, swelling may occur, which may impair the performance of the bipolar plate for a redox flow battery.

本発明は上記に鑑みなされたもので、損傷や厚みムラの発生を防ぎながら導電性を向上させることができ、しかも、電解液に対する耐久性を伸ばすことのできるレドックスフロー電池用双極板及びその製造方法を提供することを目的としている。   The present invention has been made in view of the above, it is possible to improve the conductivity while preventing the occurrence of damage and thickness unevenness, moreover, it is possible to extend the durability to the electrolyte solution bipolar plate for redox flow battery and its production It is intended to provide a way.

本発明においては上記課題を解決するため、対向する複数の複合シートの間に樹脂組成物が挟まれるものであって、
複合シートは、少なくともポリオレフィン系樹脂繊維を含有する繊維樹脂と、この繊維樹脂よりも優れた導電性の導電材とを含み、この導電材が粒子状導電材と繊維状導電材とを含有しており、
樹脂組成物は、融点が複合シートの繊維樹脂の融点よりも５℃以上低く、かつ融点がレドックスフロー電池の作動温度以上の低融点樹脂と、少なくとも粒子状導電材を有する粒子含有導電材とを含み、
複数の複合シートと樹脂組成物とが溶着して一体化されることを特徴としている。 In order to solve the above problems in the present invention, a resin composition is sandwiched between a plurality of facing composite sheets,
The composite sheet includes a fiber resin containing at least a polyolefin-based resin fiber, and a conductive material having a conductivity higher than that of the fiber resin, and the conductive material contains a particulate conductive material and a fibrous conductive material. Cage,
The resin composition comprises a low melting point resin having a melting point of 5 ° C. or more lower than that of the fiber resin of the composite sheet and a melting point of not less than the operating temperature of the redox flow battery, and a particle-containing conductive material having at least a particulate conductive material. Including,
It is characterized in that a plurality of composite sheets and a resin composition are fused and integrated.

なお、複合シートの繊維樹脂には、アラミド系樹脂繊維を含有することができる。
また、複合シートの繊維樹脂は、平均繊維長が０．５ｍｍ以上８０ｍｍ以下であることが好ましい。
また、複合シートの繊維樹脂のポリオレフィン系樹脂繊維は、ポリプロピレン系樹脂繊維とポリエチレン系樹脂繊維の少なくともいずれか一方であることが好ましい。 The fiber resin of the composite sheet may contain aramid resin fiber.
The fiber resin of the composite sheet preferably has an average fiber length of 0.5 mm or more and 80 mm or less.
The polyolefin resin fiber of the fiber resin of the composite sheet is preferably at least one of polypropylene resin fiber and polyethylene resin fiber.

また、複合シートの導電材は、粒子状導電材が黒鉛粒子であり、繊維状導電材が炭素繊維であることが好ましい。
また、複合シートの導電材の粒子状導電材は、平均粒子径が３μｍ以上５００μｍ以下の膨張化黒鉛粒子と人造黒鉛粒子の少なくともいずれか一方であると良い。
また、樹脂組成物は、低融点樹脂を３質量部以上４０質量部以下、及び粒子含有導電材を６０質量部以上９７質量部以下含むと良い。 Further, in the conductive material of the composite sheet, it is preferable that the particulate conductive material is graphite particles and the fibrous conductive material is carbon fiber.
The particulate conductive material of the conductive material of the composite sheet is preferably at least one of expanded graphite particles and artificial graphite particles having an average particle diameter of 3 μm or more and 500 μm or less.
Further, the resin composition may contain the low melting point resin in an amount of 3 parts by mass or more and 40 parts by mass or less and the particle-containing conductive material in an amount of 60 parts by mass or more and 97 parts by mass or less.

また、樹脂組成物の低融点樹脂は、熱可塑性樹脂であると良い。
また、樹脂組成物の低融点樹脂は、平均粒子径が１０μｍ以上５００μｍ以下の粒子状のポリプロピレン系樹脂あるいはポリエチレン系樹脂であることが望ましい。
また、樹脂組成物の粒子含有導電材の粒子状導電材は、平均粒子径が１μｍ以上２００μｍ以下の黒鉛粒子であることが望ましい。 Further, the low melting point resin of the resin composition is preferably a thermoplastic resin.
The low melting point resin of the resin composition is preferably a particulate polypropylene resin or polyethylene resin having an average particle diameter of 10 μm or more and 500 μm or less.
The particulate conductive material of the particle-containing conductive material of the resin composition is preferably graphite particles having an average particle size of 1 μm or more and 200 μm or less.

また、本発明においては上記課題を解決するため、請求項１ないし１０のいずれかに記載のレドックスフロー電池用双極板の製造方法であって、
金型に、複数の複合シートと樹脂組成物とをインサートして複数の複合シートの間に樹脂組成物を挟み、金型を型締めして加圧加熱することにより、レドックスフロー電池用双極板を成形することを特徴としている。 In order to solve the above problems in the present invention, the method for producing a bipolar plate for a redox flow battery according to any one of claims 1 to 10,
A bipolar plate for a redox flow battery by inserting a plurality of composite sheets and a resin composition into a mold, sandwiching the resin composition between the plurality of composite sheets, clamping the mold and heating under pressure. It is characterized by molding.

なお、金型に、複数の複合シートの一部と樹脂組成物とをインサートし、樹脂組成物に複数の複合シートの残部を重ねることにより、対向する複数の複合シートの間に樹脂組成物を挟むことができる。   Incidentally, in the mold, a part of the plurality of composite sheets and the resin composition are inserted, and the remaining part of the plurality of composite sheets is overlaid on the resin composition to form a resin composition between the plurality of facing composite sheets. Can be sandwiched.

また、金型に、樹脂組成物と複数の複合シートの一部とをインサートするとともに、金型を型締めして加圧加熱することにより、積層中間体を成形し、金型から積層中間体を脱型して反転し、この積層中間体を金型にインサートしてその樹脂組成物を露出させ、その後、積層中間体の樹脂組成物に複数の複合シートの残部を重ねることで、積層中間体の複合シートと複合シートとの間に樹脂組成物を挟むこともできる。   In addition, the resin composition and a part of the plurality of composite sheets are inserted into the mold, and the mold is clamped and heated under pressure to form a laminated intermediate, and the laminated intermediate is removed from the mold. By demolding and reversing, inserting this laminated intermediate into the mold to expose the resin composition, and then laminating the rest of the plurality of composite sheets on the resin composition of the laminated intermediate, The resin composition may be sandwiched between the composite sheets of the body.

ここで、特許請求の範囲における複合シートは、繊維樹脂、導電材である粒子状導電材、導電材である繊維状導電材、及びアラミド系樹脂繊維を液体中で混合分散してスラリーを作製し、このスラリーに凝集剤を添加して混合物を調製するとともに、この混合物をシート製造機によりシートに形成して繊維樹脂の融点未満の温度で加圧加熱し、その後、シートを乾燥させることにより、製造することができる。   Here, the composite sheet in the claims is prepared by mixing and dispersing fiber resin, a particulate conductive material that is a conductive material, a fibrous conductive material that is a conductive material, and an aramid resin fiber in a liquid to prepare a slurry. , While adding a coagulant to this slurry to prepare a mixture, by forming this mixture into a sheet by a sheet manufacturing machine and pressurizing and heating at a temperature lower than the melting point of the fiber resin, and then drying the sheet, It can be manufactured.

複合シートの導電材には、少なくとも各種の炭素系材料が含まれる。また、樹脂組成物は、樹脂と導電材とを混合又は溶融混練した粉末形態でも良いし、成形された板形態でも良い。レドックスフロー電池用双極板は、表裏両面が平坦な板、表裏両面あるいは片面に液体用の複数の流路を並べ備えた板、連続した断面略波形の屈曲板等とすることができる。   The conductive material of the composite sheet includes at least various carbon-based materials. Further, the resin composition may be in a powder form in which a resin and a conductive material are mixed or melt-kneaded, or in a molded plate form. The bipolar plate for a redox flow battery may be a plate having flat front and back surfaces, a plate having a plurality of liquid channels arranged on both front and back surfaces or one surface, a continuous bent plate having a substantially corrugated cross section, and the like.

本発明によれば、対向する複数の複合シートの間に、粒子含有導電材を有する樹脂組成物が介在し、レドックスフロー電池用双極板が単層構造ではなく、多層構造化されて強度が増すので、レドックスフロー電池用双極板の損傷を抑制し、厚みムラを防ぎながら導電性を向上させることができる。また、硫酸バナジウム等の電解液に対する耐性の向上も期待できる。   According to the present invention, a resin composition having a particle-containing conductive material is interposed between a plurality of opposed composite sheets, and a bipolar plate for a redox flow battery is not a single layer structure but has a multi-layer structure to increase strength. Therefore, it is possible to suppress damage to the bipolar plate for a redox flow battery and improve conductivity while preventing uneven thickness. Further, it is expected that the resistance to an electrolytic solution such as vanadium sulfate is improved.

本発明によれば、レドックスフロー電池用双極板の損傷や厚みムラの発生を防ぎながら導電性を向上させることができ、しかも、電解液に対する耐久性を伸ばすことができるという効果がある。また、繊維樹脂に少なくともポリオレフィン系樹脂繊維を含有するので、繊維樹脂を安価に、かつ容易に入手することができる。また、繊維樹脂のポリオレフィン系樹脂繊維は、高分子主鎖に芳香族環構造のような剛直な構造を有さず、比較的柔らかいので、レドックスフロー電池用双極板の可撓性や成形性を向上させることができる。また、耐食性や耐水性にも優れるので、硫酸バナジウム等の電解液に対する耐性も期待できる。   According to the present invention, it is possible to improve conductivity while preventing damage and uneven thickness of the bipolar plate for a redox flow battery, and further, it is possible to extend durability to an electrolytic solution. Further, since the fiber resin contains at least a polyolefin resin fiber, the fiber resin can be easily obtained at low cost. Further, the polyolefin resin fiber of the fiber resin does not have a rigid structure such as an aromatic ring structure in the polymer main chain and is relatively soft, so that the flexibility and moldability of the bipolar plate for the redox flow battery are improved. Can be improved. Further, since it is also excellent in corrosion resistance and water resistance, resistance to an electrolytic solution such as vanadium sulfate can be expected.

請求項２記載の発明によれば、繊維樹脂にアラミド系樹脂繊維を含むので、繊維樹脂同士等を適切に絡め、繊維樹脂を補強することが可能となる。また、繊維樹脂に耐熱性、強度、耐薬品性等を付与し、レドックスフロー電池用双極板の品質を向上させたり、レドックスフロー電池用双極板の材料組成を略均一化することが可能となる。   According to the invention of claim 2, since the fiber resin contains the aramid resin fiber, it is possible to appropriately entangle the fiber resins with each other and reinforce the fiber resin. Further, it becomes possible to impart heat resistance, strength, chemical resistance, etc. to the fiber resin to improve the quality of the bipolar plate for a redox flow battery and to make the material composition of the bipolar plate for a redox flow battery substantially uniform. .

請求項３記載の発明によれば、繊維樹脂の平均繊維長が０．５〜８０ｍｍの範囲内なので、分散性が向上してレドックスフロー電池用双極板の製造時に全体の組成が均一化し、部分的な物性や導電性の相違の減少が期待できる。
請求項４記載の発明によれば、ポリオレフィン系樹脂繊維がポリプロピレン系樹脂繊維とポリエチレン系樹脂繊維の少なくともいずれか一方なので、安価で入手しやすく、しかも、レドックスフロー電池用双極板に必要な耐食性を簡易に付与することが可能となる。 According to the invention of claim 3, since the average fiber length of the fiber resin is in the range of 0.5 to 80 mm, the dispersibility is improved and the entire composition is made uniform during the production of the bipolar plate for the redox flow battery, It can be expected to reduce the difference in physical properties and conductivity.
According to the invention of claim 4, since the polyolefin-based resin fiber is at least one of polypropylene-based resin fiber and polyethylene-based resin fiber, the polyolefin-based resin fiber is inexpensive and easily available, and further, the corrosion resistance required for the bipolar plate for a redox flow battery is obtained. It is possible to easily assign.

請求項５記載の発明によれば、複合シートの導電材の粒子状導電材が黒鉛粒子であり、繊維状導電材が炭素繊維なので、レドックスフロー電池用双極板の導電性と機械的強度とを共に向上させることができる。また、粒子状導電材が黒鉛粒子なので、導電材の組成や形状の制御が容易となる。また、繊維状導電材が炭素繊維なので、レドックスフロー電池用双極板の耐久性の低下のおそれが低減する。加えて、優れた耐熱性や機械的強度を得ることができ、軽量化も期待できる。   According to the invention of claim 5, since the particulate conductive material of the conductive material of the composite sheet is graphite particles and the fibrous conductive material is carbon fiber, the conductivity and mechanical strength of the bipolar plate for the redox flow battery are improved. We can improve together. Further, since the particulate conductive material is graphite particles, the composition and shape of the conductive material can be easily controlled. Further, since the fibrous conductive material is carbon fiber, the risk of deterioration of the durability of the bipolar plate for redox flow battery is reduced. In addition, excellent heat resistance and mechanical strength can be obtained, and weight reduction can be expected.

請求項６記載の発明によれば、複合シートの導電材の粒子状導電材が、平均粒子径３μｍ以上５００μｍ以下の膨張化黒鉛粒子と人造黒鉛粒子の少なくともいずれか一方なので、複合シートの製造時に複合シートから導電材が脱落するのを防止したり、レドックスフロー電池用双極板の高導電化に寄与することができる。また、レドックスフロー電池の性能を阻害する金属不純物を省略することができる。また、粒子状導電材が膨張化黒鉛粒子の場合には、優れた導電性を得ることができ、しかも、膨張化黒鉛粒子間の隙間を塞いで所定の液体の液漏れを防ぐことが可能となる。   According to the invention of claim 6, since the particulate conductive material of the conductive material of the composite sheet is at least one of expanded graphite particles having an average particle diameter of 3 μm or more and 500 μm or less and artificial graphite particles, during the production of the composite sheet. It is possible to prevent the conductive material from falling off from the composite sheet and to contribute to the high conductivity of the bipolar plate for the redox flow battery. Further, it is possible to omit the metal impurities that hinder the performance of the redox flow battery. Further, when the particulate conductive material is expanded graphite particles, excellent conductivity can be obtained, and furthermore, it is possible to prevent the liquid leakage of a predetermined liquid by closing the gaps between the expanded graphite particles. Become.

請求項７記載の発明によれば、樹脂組成物は、低融点樹脂を３質量部以上４０質量部以下、及び粒子含有導電材を６０質量部以上９７質量部以下含むので、レドックスフロー電池用双極板に実用上問題のない機械的強度と導電性を容易に付与することが可能となる。   According to the invention of claim 7, the resin composition contains the low melting point resin in an amount of 3 parts by mass or more and 40 parts by mass or less, and the particle-containing conductive material in an amount of 60 parts by mass or more and 97 parts by mass or less. It is possible to easily give the plate mechanical strength and conductivity that are practically problem-free.

請求項８記載の発明によれば、樹脂組成物の低融点樹脂が熱可塑性樹脂なので、レドックスフロー電池用双極板の成形時に低融点樹脂の流動性を適切に確保し、樹脂組成物の均一化に寄与し、部分的な相違の減少を図ることができる。また、接着性の向上により、例え硫酸バナジウム等の電解液にレドックスフロー電池用双極板が長時間漬けられても、レドックスフロー電池用双極板から導電材が脱落するのを防ぐことができる。   According to the invention of claim 8, since the low melting point resin of the resin composition is a thermoplastic resin, the fluidity of the low melting point resin is appropriately ensured during molding of the bipolar plate for a redox flow battery, and the resin composition is made uniform. It is possible to reduce the partial difference. Further, by improving the adhesiveness, it is possible to prevent the conductive material from falling off from the redox flow battery bipolar plate even if the redox flow battery bipolar plate is immersed in an electrolytic solution such as vanadium sulfate for a long time.

請求項９記載の発明によれば、低融点樹脂が、平均粒子径１０μｍ以上５００μｍ以下の粒子状のポリプロピレン系樹脂あるいはポリエチレン系樹脂なので、樹脂組成物の低融点樹脂と粒子含有導電材との分散性がさらに向上し、レドックスフロー電池用双極板の組成の均一化が期待できる。   According to the invention of claim 9, the low-melting point resin is a particulate polypropylene-based resin or polyethylene-based resin having an average particle size of 10 μm or more and 500 μm or less, so that the low-melting point resin of the resin composition and the particle-containing conductive material are dispersed. It is expected that the properties will be further improved and the composition of the bipolar plate for redox flow batteries will be uniform.

請求項１０記載の発明によれば、樹脂組成物の粒子含有導電材の粒子状導電材が、平均粒子径１μｍ以上２００μｍ以下の黒鉛粒子なので、例えレドックスフロー電池用双極板の厚さが１ｍｍ未満の場合でも、優れた導電性を得ることができ、しかも、導電経路の損失の抑制を図ることができる。   According to the invention of claim 10, since the particulate conductive material of the particle-containing conductive material of the resin composition is graphite particles having an average particle diameter of 1 μm or more and 200 μm or less, the thickness of the bipolar plate for a redox flow battery is less than 1 mm. Even in this case, excellent conductivity can be obtained, and further, loss of the conductive path can be suppressed.

請求項１１記載の発明によれば、レドックスフロー電池用双極板の厚さムラを低減し、例えレドックスフロー電池の電解液が硫酸バナジウム等でも、レドックスフロー電池用双極板の耐性を有効に確保することが可能となる。   According to the invention described in claim 11, the uneven thickness of the bipolar plate for a redox flow battery is reduced, and the resistance of the bipolar plate for a redox flow battery is effectively secured even if the electrolyte of the redox flow battery is vanadium sulfate or the like. It becomes possible.

請求項１２記載の発明によれば、複数の複合シートの一部と樹脂組成物とをインサートした後、樹脂組成物に複数の複合シートの残部を重ね、対向する複数の複合シートの間に樹脂組成物を挟むので、複合シートの一部に粉末の樹脂組成物を均一にならして配置することができる。また、飛び散り易い粉末の樹脂組成物を用いるのではなく、板体の樹脂組成物を用いれば、作業環境の汚染防止と量産性の向上が期待できる。   According to the invention of claim 12, after inserting a part of the plurality of composite sheets and the resin composition, the rest of the plurality of composite sheets is overlapped with the resin composition, and the resin is provided between the plurality of opposing composite sheets. Since the composition is sandwiched, the powdery resin composition can be evenly arranged on a part of the composite sheet. In addition, if a resin composition of a plate is used instead of a powdery resin composition that easily scatters, it can be expected to prevent contamination of the work environment and improve mass productivity.

請求項１３記載の発明によれば、成形した積層中間体の樹脂組成物に複数の複合シートの残部を重ねることで、積層中間体の複合シートと複合シートとの間に樹脂組成物を挟むので、レドックスフロー電池用双極板の製造の多様化が期待できる。また、例え使用する複数の複合シートの厚さにバラツキが存在しても、高精度の厚さを有するレドックスフロー電池用双極板を得ることが可能となる。   According to the thirteenth aspect of the present invention, the resin composition is sandwiched between the composite sheet of the laminated intermediate and the composite sheet by stacking the rest of the plurality of composite sheets on the resin composition of the molded laminated intermediate. The diversification of the manufacturing of bipolar plates for redox flow batteries can be expected. Further, even if there are variations in the thickness of a plurality of composite sheets used, it is possible to obtain a bipolar plate for a redox flow battery having a highly accurate thickness.

本発明に係るレドックスフロー電池用双極板の実施形態を模式的に示す断面説明図である。It is a section explanatory view showing typically an embodiment of a bipolar plate for redox flow batteries concerning the present invention.

以下、図面を参照して本発明の好ましい実施の形態を説明すると、本実施形態におけるレドックスフロー電池用双極板１は、図１に示すように、相対向する一対の複合シート２と、この一対の複合シート２の間に介在して挟持される樹脂組成物３とを備えた厚さ１ｍｍ未満の薄い双極板であり、一対の複合シート２と樹脂組成物３とが金型を用いた加圧加熱成形により、溶着して一体化される。   BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. A bipolar plate 1 for a redox flow battery in the present embodiment has a pair of composite sheets 2 facing each other and a pair of the composite sheets 2 as shown in FIG. Is a thin bipolar plate having a thickness of less than 1 mm, which comprises a resin composition 3 interposed and sandwiched between the composite sheets 2 of 1. and a pair of the composite sheet 2 and the resin composition 3 using a mold. By pressure heating molding, they are fused and integrated.

各複合シート２は、熱可塑性樹脂繊維を含有する繊維樹脂と、この繊維樹脂よりも優れた導電性の導電材とを含み、グラビア印刷法等の所定の印刷法により平面矩形のシートに形成される。この複合シート２は、厚さ１ｍｍ未満のレドックスフロー電池用双極板１が製造される場合、坪量が５０〜５００ｇ／ｍ２、好ましくは７０〜３００ｇ／ｍ２、より好ましくは８０〜２５０ｇ／ｍ２が良い。また、厚さ１ｍｍ未満のレドックスフロー電池用双極板１が製造される場合、薄型化の観点から、厚さが０．１ｍｍ以上０．５ｍｍ未満、好ましくは０．１ｍｍ以上０．３ｍｍ未満が良い。 Each composite sheet 2 includes a fiber resin containing a thermoplastic resin fiber and a conductive material having conductivity higher than that of the fiber resin, and is formed into a flat rectangular sheet by a predetermined printing method such as a gravure printing method. It This composite sheet 2 has a basis weight of 50 to 500 g / m 2 , preferably 70 to 300 g / m 2 , and more preferably 80 to 250 g / when the bipolar plate 1 for redox flow batteries having a thickness of less than 1 mm is manufactured. m 2 is good. Further, when the bipolar plate 1 for redox flow battery having a thickness of less than 1 mm is manufactured, the thickness is preferably 0.1 mm or more and less than 0.5 mm, preferably 0.1 mm or more and less than 0.3 mm from the viewpoint of thinning. .

複合シート２の繊維樹脂と導電材とは、繊維樹脂よりも導電材が質量比で多く含有され、繊維樹脂中に導電材が分散する。これは、繊維樹脂よりも導電材が質量比で多く含有されれば、導電性を向上させることができる他、例え酸性の強い硫酸バナジウム等の電解液にレドックスフロー電池用双極板１が長時間浸漬される場合にも、実用上問題の無い導電性や機械的強度を確保することができるからである。繊維樹脂と導電材の具体的な配合比率は、質量比で１０〜４０：６０〜９０、好ましくは１５〜３０：７０〜８５が良い。   The fiber resin and the conductive material of the composite sheet 2 contain the conductive material in a larger mass ratio than the fiber resin, and the conductive material is dispersed in the fiber resin. This is because if the conductive material is contained in a larger mass ratio than the fiber resin, the conductivity can be improved, and the redox flow battery bipolar plate 1 can be used for a long time in an electrolytic solution such as vanadium sulfate having strong acidity. This is because, even when it is immersed, it is possible to secure the conductivity and mechanical strength that pose no practical problems. The specific mixing ratio of the fiber resin and the conductive material is 10 to 40:60 to 90, preferably 15 to 30:70 to 85 in terms of mass ratio.

繊維樹脂は、熱可塑性樹脂繊維、具体的には少なくとも比較的融点の低いポリオレフィン系樹脂繊維を含有し、ポリオレフィン系樹脂繊維が入手が容易なポリプロピレン（ＰＰ）系樹脂繊維とポリエチレン（ＰＥ）系樹脂繊維の少なくともいずれか一方であるのが好ましい。   The fiber resin includes a thermoplastic resin fiber, specifically, at least a polyolefin resin fiber having a relatively low melting point, and the polyolefin resin fiber is easily available polypropylene (PP) resin fiber and polyethylene (PE) resin. It is preferably at least one of the fibers.

これは、成形時に適切な流動性を満たすことができ、必要があれば、再度加熱することにより、再び熱可塑性樹脂繊維が溶融し、成形が可能となるからである。また、ポリオレフィン系樹脂繊維を採用したのは、高分子主鎖に環構造を有するような剛直な樹脂ではなく、比較的柔軟なので、レドックスフロー電池用双極板１の可撓性や柔軟性に寄与するからである。さらに、ポリオレフィン系樹脂繊維は、耐薬品性や耐水性に優れるので、硫酸バナジウム等の電解液による加水分解が生じにくく、樹脂界面の接着劣化や樹脂の分解に起因するレドックスフロー電池用双極板１の内部の空隙発生を抑制することができるからである。   This is because appropriate fluidity can be satisfied at the time of molding, and if necessary, by heating again, the thermoplastic resin fibers are melted again and molding becomes possible. Moreover, since the polyolefin resin fiber is not a rigid resin having a ring structure in the polymer main chain but is relatively flexible, it contributes to the flexibility and flexibility of the bipolar plate 1 for a redox flow battery. Because it does. Further, since the polyolefin resin fiber is excellent in chemical resistance and water resistance, hydrolysis by an electrolytic solution such as vanadium sulfate does not easily occur, and the bipolar plate for a redox flow battery 1 caused by adhesion deterioration at the resin interface or decomposition of the resin 1 This is because it is possible to suppress the generation of voids inside the.

繊維樹脂の平均繊維長は、０．５ｍｍ以上８０ｍｍ以下、好ましくは１ｍｍ以上８０ｍｍ以下、より好ましくは１ｍｍ以上５０ｍｍ以下、さらに好ましくは２ｍｍ以上２０ｍｍ以下が最適である。これは、平均繊維長が０．５ｍｍ以上８０ｍｍ以下であれば、複合シート２の製造時の分散性が向上し、機械的強度や導電性のバラツキを抑制することができるという理由に基づく。また、繊維樹脂の繊維径は、複合シート２の製造時の分散性を向上させる観点から、０．１μｍ以上８０μｍ以下、好ましくは１μｍ以上６０μｍ以下が最適である。   The average fiber length of the fiber resin is 0.5 mm or more and 80 mm or less, preferably 1 mm or more and 80 mm or less, more preferably 1 mm or more and 50 mm or less, and further preferably 2 mm or more and 20 mm or less. This is because when the average fiber length is 0.5 mm or more and 80 mm or less, the dispersibility during manufacturing of the composite sheet 2 is improved, and variations in mechanical strength and conductivity can be suppressed. Further, the fiber diameter of the fiber resin is optimally 0.1 μm or more and 80 μm or less, preferably 1 μm or more and 60 μm or less, from the viewpoint of improving dispersibility during production of the composite sheet 2.

繊維樹脂は、ポリオレフィン系樹脂繊維の他、必要に応じ、アラミド系繊維樹脂を選択的に含有する。このアラミド系繊維樹脂は、例えばパラ系やメタ系の各単独、あるいはこれらを任意の組成比で混合した平均繊維長が１ｍｍ以上８０ｍｍ以下、好ましくは２ｍｍ以上２０ｍｍ以下の繊維樹脂からなり、レドックスフロー電池用双極板１の製造時に繊維樹脂と導電材、繊維樹脂同士を適切に縺れさせ、繊維樹脂を補強するよう機能する。このアラミド系繊維樹脂は、パルプ状やカットファイバー状等、いかなる形状等でも良いが、繊維樹脂と導電材とを適切に縺れさせる観点からすると、表面が毛羽だったパルプ状が好適である。   The fiber resin selectively contains an aramid fiber resin, if necessary, in addition to the polyolefin resin fiber. The aramid-based fiber resin is, for example, a para-based resin or a meta-based fiber resin, or a fiber resin having an average fiber length of 1 mm or more and 80 mm or less, preferably 2 mm or more and 20 mm or less, obtained by mixing these at an arbitrary composition ratio. When the bipolar plate 1 for a battery is manufactured, the fiber resin, the conductive material, and the fiber resins are appropriately entangled to function to reinforce the fiber resin. This aramid fiber resin may be in any shape such as pulp or cut fiber, but from the viewpoint of properly knitting the fiber resin and the conductive material, the pulp shape with a fluffy surface is preferable.

アラミド系繊維樹脂は、導電性に特に資するものではないので、１質量部以上７質量部以下程度添加されれば良い。このようなアラミド系繊維樹脂は、他の繊維樹脂を補強するが、補強機能に止まらず、繊維樹脂に耐熱性、強度、耐薬品性を付与することにより、レドックスフロー電池用双極板１の品質に資するよう機能する。   Since the aramid fiber resin does not particularly contribute to conductivity, it may be added in an amount of 1 part by mass or more and 7 parts by mass or less. Although such an aramid-based fiber resin reinforces other fiber resins, it does not stop at the reinforcing function, but imparts heat resistance, strength, and chemical resistance to the fiber resin, thereby improving the quality of the bipolar plate 1 for redox flow batteries. Function to contribute to.

複合シート２の導電材は、粒子状導電材と繊維状導電材とを含有する。粒子状導電材は、硫酸バナジウム等の電解液に対する耐食性を確保する観点から、黒鉛粒子とされる。この粒子状導電材の黒鉛粒子は、特に限定されるものではなく、例えば膨張化黒鉛粒子、人造黒鉛粒子、鱗片状黒鉛、球状黒鉛、又はこれらが組み合わせて併用される。   The conductive material of the composite sheet 2 contains a particulate conductive material and a fibrous conductive material. The particulate conductive material is graphite particles from the viewpoint of ensuring corrosion resistance to an electrolytic solution such as vanadium sulfate. The graphite particles of the particulate conductive material are not particularly limited, and for example, expanded graphite particles, artificial graphite particles, flake graphite, spherical graphite, or a combination thereof is used together.

これらの中では、優れた導電性を得る観点から、膨張化黒鉛粒子と人造黒鉛粒子の少なくともいずれか一方の採用が望ましい。また、粒子状導電材の黒鉛粒子の平均粒子径は、複合シート２の製造時に黒鉛粒子が脱落するのを防止する観点から、３μｍ以上５００μｍ以下、好ましくは１０μｍ以上３００μｍ以下、より好ましくは１５μｍ以上２００μｍ以下が最適である。   Among these, it is desirable to adopt at least one of expanded graphite particles and artificial graphite particles from the viewpoint of obtaining excellent conductivity. The average particle size of the graphite particles of the particulate conductive material is 3 μm or more and 500 μm or less, preferably 10 μm or more and 300 μm or less, and more preferably 15 μm or more, from the viewpoint of preventing the graphite particles from falling off during the production of the composite sheet 2. The optimum value is 200 μm or less.

導電材の繊維状導電材は、レドックスフロー電池用双極板１の面方向の導電性に寄与し、レドックスフロー電池用双極板１に機械的強度を付与するよう機能する。この繊維状導電材は、機械的強度、導電性、耐食性を得る観点から、炭素繊維が選択される。炭素繊維は、特に限定されるものではないが、例えばＰＡＮ系、ピッチ系、フェノール系、レーヨン系、又はこれらの組み合わせ等があげられる。これらの中では、レドックスフロー電池用双極板１の可撓性と強度とを共に向上させる観点から、ＰＡＮ系の炭素繊維が最適である。   The fibrous conductive material of the conductive material contributes to the conductivity in the surface direction of the bipolar plate 1 for redox flow battery and functions to give mechanical strength to the bipolar plate 1 for redox flow battery. As the fibrous conductive material, carbon fiber is selected from the viewpoint of obtaining mechanical strength, conductivity, and corrosion resistance. The carbon fiber is not particularly limited, and examples thereof include PAN-based, pitch-based, phenol-based, rayon-based, and combinations thereof. Among these, PAN-based carbon fibers are most suitable from the viewpoint of improving both flexibility and strength of the bipolar plate 1 for redox flow batteries.

繊維状導電材の平均繊維長は、一枚の複合シート２を単独で加熱圧縮成形した際の成形品の厚みよりも長いことが好ましい。これは、機械的強度に寄与する面方向に繊維状導電材が並びやすくなるという理由に基づく。繊維状導電材の具体的な平均繊維長は、複合シート２の良好な分散性と強度を確保する観点から、０．５ｍｍ以上８０ｍｍ以下、好ましくは１ｍｍ以上２０ｍｍ以下が良い。また、繊維状導電材の具体的な繊維径は、０．５μｍ以上５０μｍ以下、好ましくは２μｍ以上５０μｍ以下が好適である。   The average fiber length of the fibrous conductive material is preferably longer than the thickness of the molded product when one composite sheet 2 is heat compression molded alone. This is based on the reason that the fibrous conductive material is likely to be arranged in the surface direction that contributes to the mechanical strength. The specific average fiber length of the fibrous conductive material is 0.5 mm or more and 80 mm or less, preferably 1 mm or more and 20 mm or less, from the viewpoint of ensuring good dispersibility and strength of the composite sheet 2. The specific fiber diameter of the fibrous conductive material is 0.5 μm or more and 50 μm or less, preferably 2 μm or more and 50 μm or less.

樹脂組成物３は、融点が複合シート２の繊維樹脂の融点よりも低く、かつ融点がレドックスフロー電池の作動温度以上の低融点樹脂と、少なくとも粒子状導電材を有する粒子含有導電材とが配合された組成物であり、相対向する一対の複合シート２の対向面に加熱溶着される。この樹脂組成物３は、低融点樹脂を３質量部以上４０質量部以下含み、粒子含有導電材を６０質量部以上９７質量部含む。   The resin composition 3 includes a low melting point resin having a melting point lower than that of the fiber resin of the composite sheet 2 and having a melting point not lower than the operating temperature of the redox flow battery, and a particle-containing conductive material having at least a particulate conductive material. The composition is heated and welded to the facing surfaces of the pair of composite sheets 2 facing each other. This resin composition 3 contains the low melting point resin in an amount of 3 parts by mass or more and 40 parts by mass or less and the particle-containing conductive material in an amount of 60 parts by mass or more and 97 parts by mass.

低融点樹脂は、複合シート２の繊維樹脂よりも融点が低い熱可塑性樹脂、例えば平均粒子径が１０μｍ以上５００μｍ以下、好ましくは１０μｍ以上２０μｍ以下の粒子状のポリプロピレン（ＰＰ）系樹脂、ポリエチレン（ＰＥ）系樹脂、高密度ポリエチレン（ＨＤＰＥ）系樹脂、あるいは低密度ポリエチレン（ＬＤＰＥ）系樹脂が採用される。   The low melting point resin is a thermoplastic resin having a lower melting point than the fiber resin of the composite sheet 2, for example, a particulate polypropylene (PP) -based resin having an average particle size of 10 μm or more and 500 μm or less, preferably 10 μm or more and 20 μm or less, polyethylene (PE ) Type resin, high density polyethylene (HDPE) type resin, or low density polyethylene (LDPE) type resin is adopted.

これは、複合シート２の繊維樹脂よりも融点が低ければ、レドックスフロー電池用双極板１の成形時に複合シート２の繊維樹脂よりも先に溶融して流動し、複合シート２中の空隙に低融点樹脂が溶け込んで導電材を補填し、レドックスフロー電池用双極板１の低抵抗化に寄与させることができるからである。また、複合シート２中に導電材が入り込み、レドックスフロー電池用双極板１全体の密度が高くなることで、レドックスフロー電池用双極板１の内部に電解液等の液体が浸入し、レドックスフロー電池用双極板１の特性を阻害するのを防止することができるからである。   This is because if the melting point of the composite sheet 2 is lower than that of the fiber resin of the composite sheet 2, it will melt and flow before the fiber resin of the composite sheet 2 when the bipolar plate 1 for a redox flow battery is molded, and the voids in the composite sheet 2 will be low. This is because the melting point resin can be melted to supplement the conductive material and contribute to lowering the resistance of the bipolar plate 1 for a redox flow battery. Further, the conductive material enters the composite sheet 2 to increase the density of the entire bipolar plate 1 for redox flow battery, so that the liquid such as the electrolytic solution enters the inside of the bipolar plate 1 for redox flow battery, and the redox flow battery This is because it is possible to prevent the characteristics of the working bipolar plate 1 from being impaired.

低融点樹脂の融点は、複合シート２の繊維樹脂の融点よりも、５℃以上低く小さいことが好ましい。また、低融点樹脂の融点の下限値は、レドックスフロー電池の作動温度以上、好ましくは６０℃以上、より好ましくは１００℃以上が良い。複合シート２の繊維樹脂の融点と低融点樹脂の融点との差は、１００℃以内、好ましくは７０℃以内が良い。これは、融点の差が１００℃以内であれば、繊維樹脂が溶融する温度の加熱成形でも、過加熱による樹脂組成物３内の成形不良を抑制することができるからである。   The melting point of the low-melting resin is preferably lower than the melting point of the fiber resin of the composite sheet 2 by 5 ° C. or less. Further, the lower limit of the melting point of the low melting point resin is preferably the operating temperature of the redox flow battery or higher, preferably 60 ° C. or higher, more preferably 100 ° C. or higher. The difference between the melting point of the fiber resin of the composite sheet 2 and the melting point of the low melting point resin is 100 ° C. or less, preferably 70 ° C. or less. This is because if the difference in melting point is 100 ° C. or less, molding defects in the resin composition 3 due to overheating can be suppressed even by heat molding at a temperature at which the fiber resin melts.

なお、樹脂の融点を測定する場合には、ＪＩＳ Ｋ７１２１に基づき、樹脂を示差走査熱量計（ＤＳＣ）により測定し、測定した融解ピーク温度を融点とすることができる。２以上の融解ピークが観察されたときには、高温側の融解ピーク温度を融点とすることが好ましい。   When the melting point of the resin is measured, the resin can be measured by a differential scanning calorimeter (DSC) based on JIS K7121, and the measured melting peak temperature can be used as the melting point. When two or more melting peaks are observed, it is preferable to set the melting peak temperature on the high temperature side as the melting point.

低融点樹脂が粒子状の場合、低融点樹脂の平均粒子径と粒子含有導電材の粒子状導電材の平均粒子径の差は、３００μｍ以内、好ましくは２００μｍ以内が最適である。これは、平均粒子径の差が３００μｍ以内であれば、分散性が向上し、レドックスフロー電池用双極板１の機械的強度や導電性の部分的なバラツキが小さくなるという理由に基づく。加えて、樹脂組成物３をスクレーバ等でならす場合、作業の容易化が期待できるという理由に基づく。   When the low melting point resin is in the form of particles, the difference between the average particle size of the low melting point resin and the average particle size of the particulate conductive material of the particle-containing conductive material is optimally within 300 μm, preferably within 200 μm. This is because when the difference in average particle diameter is within 300 μm, the dispersibility is improved and the mechanical strength of the bipolar plate 1 for a redox flow battery and the partial variation in conductivity are reduced. In addition, when the resin composition 3 is smoothed with a scraper or the like, it is possible to expect the work to be facilitated.

粒子状導電材は、平均粒子径が１μｍ以上２００μｍ以下、好ましくは１０μｍ以上２００μｍ以下、より好ましくは２０μｍ以上８０μｍ以下の黒鉛粒子が使用され、この黒鉛粒子がレドックスフロー電池用双極板１の厚み方向の導電性に資するよう機能する。この黒鉛粒子は、特に限定されるものではないが、例えば膨張化黒鉛粒子、人造黒鉛粒子、鱗片状黒鉛、球状黒鉛、又はこれらが組み合わせて併用される。これらの中では、優れた導電性を得るため、膨張化黒鉛粒子と人造黒鉛粒子の少なくともいずれか一方が採用される。   As the particulate conductive material, graphite particles having an average particle size of 1 μm or more and 200 μm or less, preferably 10 μm or more and 200 μm or less, more preferably 20 μm or more and 80 μm or less are used, and the graphite particles are in the thickness direction of the bipolar plate 1 for redox flow battery. Functions to contribute to the conductivity of. The graphite particles are not particularly limited, but for example, expanded graphite particles, artificial graphite particles, flake graphite, spherical graphite, or a combination of these is used together. Among these, at least one of expanded graphite particles and artificial graphite particles is adopted in order to obtain excellent conductivity.

上記構成において、レドックスフロー電池用双極板１を製造する場合には、先ず、専用の金型を用意し、型開きした金型の下型に、予め製造しておいた一枚の複合シート２と粉末の樹脂組成物３とを順次インサートし、粉末の樹脂組成物３にスクレーバを接触させて水平に移動させ、複合シート２の表面上で粉末の樹脂組成物３をスクレーバで均一にならす。この際、１ｍｍ未満のレドックスフロー電池用双極板１を製造する場合には、複合シート２上に粉末の樹脂組成物３を単位面積（１／ｃｍ２）当たり、０．０１ｇ以上０．５ｇ、好ましくは０．０１ｇ以上０．３ｇ程度載せると良い。 In the case of manufacturing the bipolar plate 1 for redox flow battery in the above structure, first, a dedicated mold is prepared, and one composite sheet 2 manufactured in advance is placed in the lower mold of the mold opened. And the powdered resin composition 3 are sequentially inserted, the scraper is brought into contact with the powdered resin composition 3 and moved horizontally, and the powdered resin composition 3 is evenly leveled on the surface of the composite sheet 2. At this time, when the bipolar plate 1 for a redox flow battery having a size of less than 1 mm is manufactured, 0.01 g or more and 0.5 g of the powdered resin composition 3 per unit area (1 / cm 2 ) on the composite sheet 2. It is preferable to put about 0.01 g or more and about 0.3 g.

こうして粉末の樹脂組成物３を平らにならしたら、樹脂組成物３に残り一枚の複合シート２を重ねることにより、相対向する複数枚の複合シート２の間に粉末の樹脂組成物３を挟み、金型の下型に上型を型締めして加圧加熱することで、レドックスフロー電池用双極板１を圧縮成形し、その後、金型を冷却してレドックスフロー電池用双極板１を脱型すれば、三層構造のレドックスフロー電池用双極板１を製造することができる。製造されたレドックスフロー電池用双極板１は、面方向の体積抵抗値が８ｍΩ・ｃｍ以下であるのが好ましく、厚み方向の体積抵抗値が１５０ｍΩ・ｃｍ以下であるのが好ましい。   When the powdery resin composition 3 is flattened in this way, the remaining composite sheet 2 is stacked on the resin composition 3 to sandwich the powdery resin composition 3 between a plurality of opposing composite sheets 2. , The lower mold of the mold is clamped and heated under pressure to compression-mold the bipolar plate 1 for redox flow battery, and then the mold is cooled to remove the bipolar plate 1 for redox flow battery. If it is molded, the bipolar plate 1 for a redox flow battery having a three-layer structure can be manufactured. The manufactured bipolar plate 1 for a redox flow battery preferably has a plane-direction volume resistance value of 8 mΩ · cm or less, and preferably a thickness-direction volume resistance value of 150 mΩ · cm or less.

上記によれば、相対向する一対の複合シート２の間に、粒子含有導電材を有する樹脂組成物３を挟持させた三層構造の高強度のレドックスフロー電池用双極板１を製造するので、レドックスフロー電池用双極板１の損傷を防止し、厚みムラを防ぎながら導電性を著しく向上させることができる。また、硫酸バナジウム等の電解液に対する耐性を大幅に向上させることができるので、例え硫酸バナジウム等の電解液に浸漬した環境下でも、レドックスフロー電池用双極板１の性能を損なうおそれを有効に排除することができる。   According to the above, a high-strength redox flow battery bipolar plate 1 having a three-layer structure in which a resin composition 3 having a particle-containing conductive material is sandwiched between a pair of opposing composite sheets 2 is produced. It is possible to prevent the bipolar plate 1 for redox flow battery from being damaged, and to improve the conductivity remarkably while preventing uneven thickness. In addition, since the resistance to an electrolytic solution such as vanadium sulfate can be significantly improved, it is possible to effectively eliminate the possibility of impairing the performance of the bipolar plate 1 for a redox flow battery even in an environment immersed in an electrolytic solution such as vanadium sulfate. can do.

なお、上記実施形態では型開きした金型に複合シート２、粉末の樹脂組成物３、複合シート２を順次インサートしたが、何らこれに限定されるものではない。例えば、金型の下型に複合シート２、平面矩形の板に成形された樹脂組成物３、及び複合シート２を順次インサートし、一対の複合シート２の間に樹脂組成物３を挟持させても良い。この実施形態の場合、飛散し易い粉末の樹脂組成物３を用いるのではなく、板体の樹脂組成物３を用いるので、作業環境の汚染防止と量産性の向上とが大いに期待できる。   In the above embodiment, the composite sheet 2, the powdered resin composition 3, and the composite sheet 2 were sequentially inserted into the opened mold, but the present invention is not limited to this. For example, the composite sheet 2, the resin composition 3 formed into a flat rectangular plate, and the composite sheet 2 are sequentially inserted into the lower mold of the mold, and the resin composition 3 is sandwiched between the pair of composite sheets 2. Is also good. In the case of this embodiment, since the resin composition 3 of the plate is used instead of the resin composition 3 of the powder that is easily scattered, it is possible to greatly prevent the contamination of the working environment and improve the mass productivity.

また、型開きした金型の下型に、粉末の樹脂組成物３と一枚の複合シート２とを順次インサートするとともに、金型を型締めして加圧加熱することにより、積層中間体を成形し、型開きした金型から積層中間体を脱型して表裏反転し、この積層中間体を型開きした金型の下型に再度インサートしてその樹脂組成物３を露出させ、その後、積層中間体の樹脂組成物３に複合シート２の残り一枚を重ねることで、積層中間体の複合シート２と複合シート２との間に樹脂組成物３を挟持させても良い。この実施形態の場合、例え使用する一対の複合シート２の厚さにバラツキが存在しても、高精度の厚さのレドックスフロー電池用双極板１を得ることができる。   In addition, the powder resin composition 3 and one composite sheet 2 are sequentially inserted into the lower mold of the opened mold, and the mold is clamped and heated under pressure to form a laminated intermediate. After molding, the laminated intermediate is demolded from the opened mold and turned upside down, and this laminated intermediate is inserted again into the lower mold of the opened mold to expose the resin composition 3, and then, The resin composition 3 may be sandwiched between the composite sheet 2 and the composite sheet 2 that are the lamination intermediates by stacking the remaining one of the composite sheets 2 on the resin composition 3 that is the lamination intermediate. In the case of this embodiment, it is possible to obtain the bipolar plate 1 for a redox flow battery with a highly accurate thickness even if there is a variation in the thickness of the pair of composite sheets 2 used.

以下、本発明に係るレドックスフロー電池用双極板及びその製造方法の実施例を比較例と共に説明する。
〔実施例１〕
先ず、レドックスフロー電池用双極板の複合シートを製造すべく、繊維樹脂として、ポリプロピレン繊維２５質量部、導電材の粒子状導電材として、膨張化黒鉛粒子６０質量部、導電材の繊維状導電材として、炭素繊維１０質量部、及びアラミド系樹脂繊維として、アラミド繊維５質量部を用意（表１参照）し、これらを水中で混合分散して固形分３％のスラリーを作製した。 Hereinafter, examples of a bipolar plate for a redox flow battery and a method for manufacturing the same according to the present invention will be described together with comparative examples.
[Example 1]
First, in order to manufacture a bipolar sheet composite sheet for a redox flow battery, 25 parts by mass of polypropylene fiber as a fiber resin, 60 parts by mass of expanded graphite particles as a particulate conductive material of a conductive material, and a fibrous conductive material of a conductive material. As 10 parts by mass of carbon fiber and 5 parts by mass of aramid fiber as aramid resin fiber were prepared (see Table 1), these were mixed and dispersed in water to prepare a slurry having a solid content of 3%.

ポリプロピレン繊維〔製品名：Ｊ１０５Ｈ 株式会社プライムポリマー製〕は、融点１６６℃、平均繊維径２０μｍ、平均繊維長５ｍｍの長さにカットした短繊維を使用した。また、膨張化黒鉛粒子は、平均粒子径が２００μｍのＢＳＰ‐２００Ａ〔製品名 富士黒鉛工業株式会社製〕を使用した。炭素繊維は、炭素繊維トレカ〔（登録商標） 東レ株式会社製〕のカットファイバーＴ００８‐００３（繊維φ７μｍ、カット長３ｍｍ）を使用した。また、アラミド繊維は、長さ３ｍｍのケプラーカットファイバー〔製品名：Ｋｅｖｌａｒ（登録商標） 東レ・デュポン株式会社製〕とした。   As the polypropylene fiber [product name: J105H made by Prime Polymer Co., Ltd.], a short fiber cut into a length of 166 ° C., an average fiber diameter of 20 μm and an average fiber length of 5 mm was used. The expanded graphite particles used were BSP-200A (product name: Fuji Graphite Industry Co., Ltd.) having an average particle diameter of 200 μm. As the carbon fiber, a cut fiber T008-003 (fiber φ7 μm, cut length 3 mm) of carbon fiber trading card [registered trademark (Toray Co., Ltd.)] was used. The aramid fiber was a 3 mm long Kepler-cut fiber [Product name: Kevlar (registered trademark) manufactured by Toray DuPont Co., Ltd.].

なお、繊維樹脂は、公知の溶融紡糸法等により、樹脂（製品名）を繊維化してカットしたものである。この点については、全ての実施例と比較例で同様である。   The fiber resin is a resin (product name) made into fibers by a known melt spinning method or the like and cut. This point is the same in all Examples and Comparative Examples.

固形分３％のスラリーを作製したら、このスラリーに凝集剤を添加して混合物を調製し、この混合物をメッシュ構造の２５ｃｍ角のシート機により抄紙シートに形成し、抄紙シートを１００℃に加熱したプレス機にセットして約２００ｋｇ／ｃｍ２の圧力で約５分間加圧加熱し、その後、抄紙シートを乾燥させて水分を除去することにより、ポリプロピレン繊維に膨張化黒鉛粒子と炭素繊維とが均一に分散して絡んだ厚さ０．７ｍｍ，坪量１００ｇ／ｍ２の複合シートＡを必要数製造した。凝集剤は、カチオン系ポリアクリル酸ソーダ０．００１質量部と、アニオン系ポリアクリル酸ソーダ０．００００１質量部とからなる添加物とした。 When a slurry having a solid content of 3% was prepared, a coagulant was added to the slurry to prepare a mixture, the mixture was formed into a papermaking sheet by a 25 cm square sheet machine having a mesh structure, and the papermaking sheet was heated to 100 ° C. It is set in a press and heated at a pressure of about 200 kg / cm 2 for about 5 minutes, and then the papermaking sheet is dried to remove water, so that the expanded graphite particles and the carbon fibers are uniformly dispersed in the polypropylene fiber. The required number of composite sheets A having a thickness of 0.7 mm and a basis weight of 100 g / m 2 dispersed and entangled with each other were manufactured. The coagulant was an additive composed of 0.001 parts by mass of cationic sodium polyacrylate and 0.00001 parts by mass of anionic sodium polyacrylate.

次に、専用の金型を用意し、型開きした金型の下型に、製造した一枚の複合シートＡと粉末の樹脂組成物とを順次インサートし、その後、粉末の樹脂組成物にスクレーバを接触させて水平に移動させ、複合シートＡの表面上で粉末の樹脂組成物をスクレーバで均一にならして平坦化した。   Next, a dedicated mold is prepared, and the manufactured composite sheet A and the powdered resin composition are sequentially inserted into the lower mold of the mold, and then the powdered resin composition is scraped. Were contacted with each other and moved horizontally, and the powdered resin composition was leveled on the surface of the composite sheet A by a scraper to be flattened.

樹脂組成物は、低融点樹脂を１０質量部、及び粒子含有導電材を９０質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表２に示すように、平均粒子径が１８μｍで融点が１４６℃のポリプロピレン樹脂〔製品名：フロービーズ 住友精化株式会社製〕を用いた。また、粒子含有導電材は、表２に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕を採用した。   The resin composition was 20.8 g of a composition containing 10 parts by mass of the low melting point resin and 90 parts by mass of the particle-containing conductive material. As the low melting point resin of this resin composition, as shown in Table 2, a polypropylene resin having an average particle diameter of 18 μm and a melting point of 146 ° C. [Product name: Flow beads manufactured by Sumitomo Seika Chemicals Co., Ltd.] was used. As the particle-containing conductive material, as shown in Table 2, artificial graphite particles having an average particle diameter of 45 μm (product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.) were used.

次いで、樹脂組成物に残り一枚の複合シートＡを重ねることにより、相対向する複数枚の複合シートＡの間に粉末の樹脂組成物を挟み、残り一枚の複合シートＡに金型の上型を搭載するとともに、２２０℃の温度に設定した金型を２０ＭＰａで強く型締めして加圧加熱し、上下の熱板の温度が３０℃の冷却用の圧縮成形機に直ちに移載し、金型の温度が８０℃以下になるまで２０ＭＰａの圧力で加圧冷却することにより、レドックスフロー電池用双極板を圧縮成形した。   Then, by stacking the remaining composite sheet A on the resin composition, the powdery resin composition is sandwiched between the plurality of composite sheets A facing each other, and the remaining composite sheet A is placed on the mold. While mounting the mold, the mold set at a temperature of 220 ° C. is strongly clamped at 20 MPa, heated under pressure, and immediately transferred to a compression molding machine for cooling, where the temperature of the upper and lower hot plates is 30 ° C. The bipolar plate for a redox flow battery was compression-molded by pressurizing and cooling at a pressure of 20 MPa until the temperature of the mold became 80 ° C. or lower.

レドックスフロー電池用双極板を圧縮成形したら、金型からレドックスフロー電池用双極板を脱型し、２５ｃｍ×２５ｃｍ、厚さ０．３０〜０．３３ｍｍのレドックスフロー電池用双極板を製造した。   After the compression molding of the redox flow battery bipolar plate, the redox flow battery bipolar plate was removed from the mold to produce a redox flow battery bipolar plate having a size of 25 cm × 25 cm and a thickness of 0.30 to 0.33 mm.

次に、製造したレドックスフロー電池用双極板の機械的強度である初期の引張強度、ｐＨ＝−０．６８の５価硫酸バナジウム水溶液中にレドックスフロー電池用双極板を１００時間浸漬した後の引張強度をそれぞれ測定して表５にまとめた。また、レドックスフロー電池用双極板の導電性として、面方向の体積抵抗値と厚み方向の体積抵抗値とをそれぞれ測定して表５にまとめた。さらに、レドックスフロー電池用双極板の割れ発生の有無、換言すれば、柔軟性や強度についても、試験を実施して表５にまとめた。   Next, the tensile strength after the bipolar plate for a redox flow battery was immersed for 100 hours in an aqueous solution of vanadium pentavalent sulfate having an initial tensile strength, pH = -0.68, which is the mechanical strength of the manufactured bipolar plate for a redox flow battery. The respective strengths were measured and summarized in Table 5. Further, as the conductivity of the bipolar plate for a redox flow battery, the volume resistance value in the plane direction and the volume resistance value in the thickness direction were measured and summarized in Table 5. Furthermore, the presence or absence of cracking of the bipolar plate for a redox flow battery, in other words, the flexibility and strength were also tested and summarized in Table 5.

・初期の引張強度
レドックスフロー電池用双極板の初期の引張強度については、ＪＩＳ Ｋ６２５１に基づき、レドックスフロー電池用双極板を１号ダンベル試験片に打ち抜き、ＲＴＣ‐１３１０Ａ〔製品名 株式会社オリエンテック製〕を使用し、引張速度１０ｍｍ／ｍｉｎの条件で引張試験を実施してその測定値を初期の引張強度値とした。 ・ Initial tensile strength Regarding the initial tensile strength of the bipolar plate for redox flow batteries, based on JIS K6251, the bipolar plate for redox flow batteries was punched into No. 1 dumbbell test piece, RTC-1310A [Product name: Orientec Co., Ltd. ] Was used and a tensile test was carried out under the condition of a tensile speed of 10 mm / min, and the measured value was taken as the initial tensile strength value.

・レドックスフロー電池用双極板を１００時間浸漬した後の引張強度
ｐＨ＝−０．６８の５価硫酸バナジウム水溶液中にレドックスフロー電池用双極板を１００時間浸漬した後の引張強度については、ＪＩＳ Ｋ６２５１に基づき、レドックスフロー電池用双極板を１号ダンベル試験片に打ち抜き、ポリエチレン製の容器にｐＨ＝−０．６８の５価硫酸バナジウム水溶液を充填するとともに、この５価硫酸バナジウム水溶液中に１号ダンベル試験片を１００時間浸漬した後、ＲＴＣ‐１３１０Ａ〔製品名 株式会社オリエンテック製〕を使用し、引張速度１０ｍｍ／ｍｉｎの条件で引張試験を実施してその測定値を１００時間浸漬した後の引張強度値とした。 -Tensile strength after dipping the redox flow battery bipolar plate for 100 hours. Regarding the tensile strength after dipping the redox flow battery bipolar plate for 100 hours in a pentavalent vanadium sulfate aqueous solution of pH = -0.68, JIS K6251 is used. Based on the above, a bipolar plate for a redox flow battery was punched out into a No. 1 dumbbell test piece, a polyethylene container was filled with a pentavalent vanadium sulfate aqueous solution having a pH of -0.68, and No. 1 was added to the pentavalent vanadium sulfate aqueous solution. After immersing the dumbbell test piece for 100 hours, RTC-1310A (product name, manufactured by Orientec Co., Ltd.) was used to perform a tensile test at a tensile speed of 10 mm / min, and the measured value was immersed for 100 hours. The tensile strength value was used.

ｐＨを測定する場合には、ｐＨ計〔製品名：Ｆ２２‐ＩＩ 株式会社堀場製作所製〕を使用し、測定電極を９６１０‐１０Ｄ〔製品名 株式会社堀場製作所製〕とした。上記引張り試験は、室温中で３回実施し、測定した値の平均値を測定値とした。   When measuring pH, a pH meter [Product name: F22-II, manufactured by Horiba, Ltd.] was used, and a measuring electrode was 9610-10D [Product name, manufactured by Horiba, Ltd.]. The tensile test was performed three times at room temperature, and the average value of the measured values was used as the measured value.

・面方向の体積抵抗値
レドックスフロー電池用双極板の面方向の体積抵抗値は、四端子四探針法により測定した。具体的には、２５ｃｍ×２５ｃｍのレドックスフロー電池用双極板から５ｃｍ×５ｃｍの大きさの試験片を２５枚切り出し、各試験片の体積抵抗値を測定機である低抵抗率計〔製品名：ロレスタＧＰ ＭＣＰ‐Ｔ６１０ 三菱化学株式会社製〕により測定し、測定した値の平均値を面方向の体積抵抗値とした。 -Volume resistance value in the plane direction The volume resistance value in the plane direction of the bipolar plate for redox flow battery was measured by the four-terminal four-probe method. Specifically, 25 test pieces with a size of 5 cm × 5 cm were cut out from a 25 cm × 25 cm bipolar plate for a redox flow battery, and the volume resistivity of each test piece was measured with a low resistivity meter [product name: Loresta GP MCP-T610 manufactured by Mitsubishi Chemical Corporation], and the average value of the measured values was taken as the volume resistance value in the plane direction.

・厚み方向の体積抵抗値
レドックスフロー電池用双極板の厚み方向の体積抵抗値については、先ず、２５ｃｍ×２５ｃｍのレドックスフロー電池用双極板から５ｃｍ×２．５ｃｍの大きさの試験片を切り出し、この試験片をガラス管の間に挟んだ。ガラス管は、φ１ｃｍのガラスＵ字管の屈曲した底部が切断され、この切断された底部に螺子穴付きのホルダが接着されたタイプとした。 -Volume resistance value in the thickness direction Regarding the volume resistance value in the thickness direction of the redox flow battery bipolar plate, first, a test piece of 5 cm x 2.5 cm was cut out from the 25 cm x 25 cm redox flow battery bipolar plate. The test piece was sandwiched between glass tubes. The glass tube was of a type in which a bent U-shaped tube having a diameter of 1 cm was cut, and a holder having a screw hole was bonded to the cut bottom.

試験片をガラス管の間に挟んだら、試験片とガラス管の両側部との間から水銀が漏れないよう螺子で固定し、ガラス管の両側部に水銀を一定量注入するとともに、水銀と用意した抵抗計〔日置電機株式会社製〕とを用意したリード線で接続し、導通するよう厚み方向の測定値を測定した後、以下の式で厚み方向の体積抵抗値に換算した。   After sandwiching the test piece between the glass tubes, fix it with a screw so that mercury does not leak between the test piece and both sides of the glass tube, inject a certain amount of mercury into both sides of the glass tube, and prepare with mercury. A resistance meter (manufactured by Hioki Denki Co., Ltd.) was connected with a prepared lead wire, and the measured value in the thickness direction was measured so as to conduct electricity, and then converted into the volume resistance value in the thickness direction by the following formula.

厚み方向の体積抵抗値〔ｍΩ・ｃｍ〕＝厚み方向の抵抗値〔ｍΩ〕×０．５〔ｃｍ〕×０．５〔ｃｍ〕×π÷試験片の厚み〔ｃｍ〕   Volume resistance value in the thickness direction [mΩ · cm] = resistance value in the thickness direction [mΩ] × 0.5 [cm] × 0.5 [cm] × π / thickness of test piece [cm]

厚み方向の抵抗値は、面方向の体積抵抗値を測定した５ｃｍ×５ｃｍの試験片を半分に切断して５ｃｍ×２．５ｃｍの大きさの試験片を複数枚形成し、この複数枚の試験片の厚み方向の抵抗値をそれぞれ測定し、上記式で体積抵抗値に換算した値の平均値とした。   The resistance value in the thickness direction is obtained by cutting a 5 cm × 5 cm test piece whose volume resistance value in the surface direction is measured into halves to form a plurality of 5 cm × 2.5 cm test pieces. The resistance value in the thickness direction of each piece was measured, and the average value of the values converted into the volume resistance value by the above formula was used.

厚みの測定は、５ｃｍ×２．５ｃｍの大きさの試験片を２５枚形成し、各試験片の厚みを硫酸バナジウム電解液の浸漬前後で測定器〔製品名：ＩＤ‐ＣＸ 株式会社ミツトヨ製〕により測定し、測定した値の平均値とした。   The thickness is measured by forming 25 test pieces each having a size of 5 cm × 2.5 cm, and measuring the thickness of each test piece before and after the immersion of the vanadium sulfate electrolyte solution [Product name: ID-CX manufactured by Mitutoyo Corporation] The average value of the measured values was used.

・レドックスフロー電池用双極板の割れ発生の有無
レドックスフロー電池用双極板の割れ発生の有無、換言すれば、柔軟性や強度については、ｐＨ＝−０．６８の５価硫酸バナジウム水溶液中に浸漬する前のレドックスフロー電池用双極板、及び浸漬した後のレドックスフロー電池用双極板を対角線上の両端部でそれぞれ折り曲げ、両端部が接触するまでにレドックスフロー電池用双極板に割れが発生するか否かを目視で評価した。 ・ Presence of cracks in the bipolar plate for redox flow batteries: Presence or absence of cracks in the bipolar plate for redox flow batteries, in other words, regarding flexibility and strength, dipping in an aqueous solution of pentavalent vanadium sulfate having a pH of −0.68. Bend the bipolar plate for redox flow battery before and the bipolar plate for redox flow battery after soaking at the both ends on the diagonal line.Will the redox flow battery bipolar plate be cracked before both ends contact each other? Whether or not it was visually evaluated.

〔実施例２〕
先ず、レドックスフロー電池用双極板の複合シートについては、実施例１の複合シートＡをそのまま採用した。
次に、専用の金型を用意し、型開きした金型の下型に、製造した一枚の複合シートＡと粉末の樹脂組成物とを順次インサートし、その後、粉末の樹脂組成物にスクレーバを接触させて水平に移動させ、複合シートの表面上で粉末の樹脂組成物をスクレーバで均一にならして平坦化した。 [Example 2]
First, as the composite sheet of the bipolar plate for the redox flow battery, the composite sheet A of Example 1 was used as it was.
Next, a dedicated mold is prepared, and the manufactured composite sheet A and the powdered resin composition are sequentially inserted into the lower mold of the mold, and then the powdered resin composition is scraped. Were contacted with each other and moved horizontally, and the powdery resin composition was leveled on the surface of the composite sheet by a scraper to be flattened.

樹脂組成物は、低融点樹脂を１０質量部、及び粒子含有導電材を９０質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表２に示すように、融点が１３５℃の高密度ポリエチレン樹脂〔製品名：ＨＤＰＥ１７００Ｊ 株式会社プライムポリマー製〕を冷凍粉砕した後、３２メッシュの篩を通過した高密度ポリエチレン樹脂を使用した。また、粒子含有導電材は、表２に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕を用いた。
その他は実施例１と同様とし、２５ｃｍ×２５ｃｍ、厚さ０．３０〜０．３３ｍｍのレドックスフロー電池用双極板を製造した。 The resin composition was 20.8 g of a composition containing 10 parts by mass of the low melting point resin and 90 parts by mass of the particle-containing conductive material. As shown in Table 2, the low melting point resin of this resin composition was obtained by freeze-grinding a high-density polyethylene resin having a melting point of 135 ° C. (product name: HDPE1700J made by Prime Polymer Co., Ltd.) and then passing through a 32 mesh sieve. High density polyethylene resin was used. As the particle-containing conductive material, as shown in Table 2, artificial graphite particles having an average particle diameter of 45 μm (product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.) were used.
Others were the same as in Example 1, and a bipolar plate for a redox flow battery having a size of 25 cm × 25 cm and a thickness of 0.30 to 0.33 mm was manufactured.

〔実施例３〕
先ず、レドックスフロー電池用双極板の複合シートについては、実施例１の複合シートＡをそのまま採用した。
次に、専用の金型を用意し、型開きした金型の下型に、製造した一枚の複合シートＡと粉末の樹脂組成物とを順次インサートし、その後、粉末の樹脂組成物にスクレーバを接触させて水平に移動させ、複合シートの表面上で粉末の樹脂組成物をスクレーバで均一にならして平坦化した。 [Example 3]
First, as the composite sheet of the bipolar plate for the redox flow battery, the composite sheet A of Example 1 was used as it was.
Next, a dedicated mold is prepared, and the manufactured composite sheet A and the powdered resin composition are sequentially inserted into the lower mold of the mold, and then the powdered resin composition is scraped. Were contacted with each other and moved horizontally, and the powdery resin composition was leveled on the surface of the composite sheet by a scraper to be flattened.

樹脂組成物は、低融点樹脂を１０質量部、及び粒子含有導電材を９０質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表２に示すように、平均粒子径が２０μｍで融点が１０９℃の低密度ポリエチレン樹脂〔製品名：ＬＤＰＥ ＵＦ１．５Ｎ 住友精化株式会社製〕を用いた。また、粒子含有導電材は、表２に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕を用いた。
その他は実施例１と同様とし、２５ｃｍ×２５ｃｍ、厚さ０．３０〜０．３３ｍｍのレドックスフロー電池用双極板を製造した。 The resin composition was 20.8 g of a composition containing 10 parts by mass of the low melting point resin and 90 parts by mass of the particle-containing conductive material. As the low melting point resin of this resin composition, as shown in Table 2, a low density polyethylene resin having an average particle diameter of 20 μm and a melting point of 109 ° C. [Product name: LDPE UF1.5N manufactured by Sumitomo Seika Chemicals Co., Ltd.] was used. . As the particle-containing conductive material, as shown in Table 2, artificial graphite particles having an average particle diameter of 45 μm (product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.) were used.
Others were the same as in Example 1, and a bipolar plate for a redox flow battery having a size of 25 cm × 25 cm and a thickness of 0.30 to 0.33 mm was manufactured.

〔実施例４〕
基本的には実施例１と同様だが、樹脂組成物を変更した。すなわち、樹脂組成物は、低融点樹脂を２０質量部、及び粒子含有導電材を８０質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表２に示すように、平均粒子径が１８μｍで融点が１４６℃のポリプロピレン樹脂〔製品名：フロービーズ 住友精化株式会社製〕を用いた。また、粒子含有導電材は、表２に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕を採用した。 [Example 4]
Basically the same as in Example 1, but the resin composition was changed. That is, the resin composition was 20.8 g of a composition containing 20 parts by mass of the low melting point resin and 80 parts by mass of the particle-containing conductive material. As the low melting point resin of this resin composition, as shown in Table 2, a polypropylene resin having an average particle diameter of 18 μm and a melting point of 146 ° C. [Product name: Flow beads manufactured by Sumitomo Seika Chemicals Co., Ltd.] was used. As the particle-containing conductive material, as shown in Table 2, artificial graphite particles having an average particle diameter of 45 μm (product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.) were used.

〔実施例５〕
基本的には実施例１と同様にレドックスフロー電池用双極板を製造したが、樹脂組成物を変更した。すなわち、樹脂組成物は、低融点樹脂を２０質量部、及び粒子含有導電材を８０質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表２に示すように、平均粒子径が１８μｍで融点が１４６℃のポリプロピレン樹脂〔製品名：フロービーズ 住友精化株式会社製〕を用いた。また、粒子含有導電材は、表２に示すように、平均粒子径が５０μｍの球状黒鉛粒子〔製品名：ＣＧＢ５０ 日本黒鉛工業株式会社製〕を採用した。 [Example 5]
Basically, a bipolar plate for a redox flow battery was manufactured in the same manner as in Example 1, but the resin composition was changed. That is, the resin composition was 20.8 g of a composition containing 20 parts by mass of the low melting point resin and 80 parts by mass of the particle-containing conductive material. As the low melting point resin of this resin composition, as shown in Table 2, a polypropylene resin having an average particle diameter of 18 μm and a melting point of 146 ° C. [Product name: Flow beads manufactured by Sumitomo Seika Chemicals Co., Ltd.] was used. As the particle-containing conductive material, as shown in Table 2, spherical graphite particles having an average particle diameter of 50 μm (product name: CGB50 manufactured by Nippon Graphite Industry Co., Ltd.) were adopted.

〔実施例６〕
基本的には実施例１と同様にレドックスフロー電池用双極板を製造したが、樹脂組成物を変更した。樹脂組成物は、低融点樹脂を２０質量部、及び粒子含有導電材を８０質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表２に示すように、平均粒子径が１８μｍで融点が１４６℃のポリプロピレン樹脂〔製品名：フロービーズ 住友精化株式会社製〕を用いた。また、粒子含有導電材は、表２に示すように、平均粒子径が２０μｍの膨張化黒鉛粒子〔製品名：ＢＳＰ‐２０Ａ 富士黒鉛工業株式会社製〕を採用した。 [Example 6]
Basically, a bipolar plate for a redox flow battery was manufactured in the same manner as in Example 1, but the resin composition was changed. The resin composition was 20.8 g of a composition containing 20 parts by mass of the low melting point resin and 80 parts by mass of the particle-containing conductive material. As the low melting point resin of this resin composition, as shown in Table 2, a polypropylene resin having an average particle diameter of 18 μm and a melting point of 146 ° C. [Product name: Flow beads manufactured by Sumitomo Seika Chemicals Co., Ltd.] was used. As the particle-containing conductive material, as shown in Table 2, expanded graphite particles having an average particle diameter of 20 μm (product name: BSP-20A manufactured by Fuji Graphite Industry Co., Ltd.) were used.

〔実施例７〕
基本的には実施例１と同様にレドックスフロー電池用双極板を製造したが、樹脂組成物を変更した。樹脂組成物は、低融点樹脂を２０質量部、及び粒子含有導電材を８０質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表２に示すように、平均粒子径が１８μｍで融点が１４６℃のポリプロピレン樹脂〔製品名：フロービーズ 住友精化株式会社製〕を用いた。また、粒子含有導電材は、表２に示すように、平均粒子径が８０μｍの鱗状黒鉛粒子〔製品名：ＣＢ‐１００ 日本黒鉛工業株式会社製〕に変更した。 [Example 7]
Basically, a bipolar plate for a redox flow battery was manufactured in the same manner as in Example 1, but the resin composition was changed. The resin composition was 20.8 g of a composition containing 20 parts by mass of the low melting point resin and 80 parts by mass of the particle-containing conductive material. As the low melting point resin of this resin composition, as shown in Table 2, a polypropylene resin having an average particle diameter of 18 μm and a melting point of 146 ° C. [Product name: Flow beads manufactured by Sumitomo Seika Chemicals Co., Ltd.] was used. Further, as shown in Table 2, the particle-containing conductive material was changed to scaly graphite particles having an average particle diameter of 80 μm (product name: CB-100 manufactured by Nippon Graphite Industry Co., Ltd.).

〔実施例８〕
基本的には実施例１と同様だが、樹脂組成物を変更した。すなわち、樹脂組成物は、低融点樹脂を３５質量部、及び粒子含有導電材を６５質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表３に示すように、平均粒子径が１８μｍで融点が１４６℃のポリプロピレン樹脂〔製品名：フロービーズ 住友精化株式会社製〕を用いた。また、粒子含有導電材は、表３に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕に変更した。 [Example 8]
Basically the same as in Example 1, but the resin composition was changed. That is, the resin composition was 20.8 g of a composition containing 35 parts by mass of the low melting point resin and 65 parts by mass of the particle-containing conductive material. As the low melting point resin of this resin composition, as shown in Table 3, a polypropylene resin having an average particle diameter of 18 μm and a melting point of 146 ° C. [Product name: Flow beads manufactured by Sumitomo Seika Chemicals Co., Ltd.] was used. As shown in Table 3, the particle-containing conductive material was changed to artificial graphite particles having an average particle diameter of 45 μm (product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.).

レドックスフロー電池用双極板を製造したら、このレドックスフロー電池用双極板の機械的強度である初期の引張強度、ｐＨ＝−０．６８の５価硫酸バナジウム水溶液中にレドックスフロー電池用双極板を１００時間浸漬した後の引張強度をそれぞれ測定して表６にまとめた。また、レドックスフロー電池用双極板の導電性として、面方向の体積抵抗値と厚み方向の体積抵抗値とをそれぞれ測定して表６にまとめた。レドックスフロー電池用双極板の割れ発生の有無（柔軟性や強度）についても、試験を実施して表６に記載した。   After manufacturing the bipolar plate for a redox flow battery, 100% of the bipolar plate for a redox flow battery was added to an aqueous solution of vanadium sulphate having an initial tensile strength, pH = -0.68, which is the mechanical strength of the bipolar plate for a redox flow battery. The tensile strength after soaking for each time was measured and summarized in Table 6. As the conductivity of the bipolar plate for a redox flow battery, the volume resistance value in the plane direction and the volume resistance value in the thickness direction were measured and summarized in Table 6. Whether or not the bipolar plate for a redox flow battery was cracked (flexibility and strength) was also tested and described in Table 6.

〔実施例９〕
先ず、レドックスフロー電池用双極板の複合シートを製造すべく、繊維樹脂として、ポリプロピレン繊維２０質量部、導電材の粒子状導電材として、膨張化黒鉛粒子７０質量部、導電材の繊維状導電材として、炭素繊維５質量部、及びアラミド系樹脂繊維として、アラミド繊維５質量部を用意（表１参照）し、これらを水中で混合分散して固形分３％のスラリーを作製した。 [Example 9]
First, in order to manufacture a composite sheet of a bipolar plate for a redox flow battery, 20 parts by mass of polypropylene fiber as a fiber resin, 70 parts by mass of expanded graphite particles as a particulate conductive material of a conductive material, and a fibrous conductive material of a conductive material. As 5 parts by mass of carbon fiber and 5 parts by mass of aramid fiber as aramid resin fiber were prepared (see Table 1), these were mixed and dispersed in water to prepare a slurry having a solid content of 3%.

ポリプロピレン繊維〔製品名：Ｊ１０５Ｈ 株式会社プライムポリマー製〕は、融点１６６℃、平均繊維径２０μｍ、平均繊維長５ｍｍの長さにカットした短繊維を使用した。また、膨張化黒鉛粒子は、平均粒子径が２０μｍのＢＳＰ‐２０Ａ〔製品名 富士黒鉛工業株式会社製〕に変更した。炭素繊維は、炭素繊維トレカ〔（登録商標） 東レ株式会社製〕のカットファイバーＴ００８‐００３（繊維φ７μｍ、カット長３ｍｍ）を使用した。また、アラミド繊維は、長さ３ｍｍのケプラーカットファイバー〔製品名：Ｋｅｖｌａｒ（登録商標） 東レ・デュポン株式会社製〕とした。   As the polypropylene fiber [product name: J105H made by Prime Polymer Co., Ltd.], a short fiber cut into a length of 166 ° C., an average fiber diameter of 20 μm and an average fiber length of 5 mm was used. Further, the expanded graphite particles were changed to BSP-20A [Product name: Fuji Graphite Industry Co., Ltd.] having an average particle diameter of 20 μm. As the carbon fiber, a cut fiber T008-003 (fiber φ7 μm, cut length 3 mm) of carbon fiber trading card [registered trademark (Toray Co., Ltd.)] was used. The aramid fiber was a 3 mm long Kepler-cut fiber [Product name: Kevlar (registered trademark) manufactured by Toray DuPont Co., Ltd.].

固形分３％のスラリーを作製したら、このスラリーに凝集剤を添加して混合物を調製し、この混合物をメッシュ構造の２５ｃｍ角のシート機により抄紙シートに形成し、抄紙シートを１００℃に加熱したプレス機にセットして約２００ｋｇ／ｃｍ２の圧力で約５分間加圧加熱し、その後、抄紙シートを乾燥させて水分を除去することにより、ポリプロピレン繊維に膨張化黒鉛粒子と炭素繊維とが均一に分散して絡んだ厚さ０．７ｍｍ，坪量１００ｇ／ｍ２の複合シートＢを必要数製造した。凝集剤は、カチオン系ポリアクリル酸ソーダ０．００１質量部と、アニオン系ポリアクリル酸ソーダ０．００００１質量部とからなる添加物とした。 When a slurry having a solid content of 3% was prepared, a coagulant was added to the slurry to prepare a mixture, the mixture was formed into a papermaking sheet by a 25 cm square sheet machine having a mesh structure, and the papermaking sheet was heated to 100 ° C. It is set in a press and heated at a pressure of about 200 kg / cm 2 for about 5 minutes, and then the papermaking sheet is dried to remove water, so that the expanded graphite particles and the carbon fibers are uniformly dispersed in the polypropylene fiber. The necessary number of composite sheets B having a thickness of 0.7 mm and a basis weight of 100 g / m 2 dispersed and entangled with each other were manufactured. The coagulant was an additive composed of 0.001 parts by mass of cationic sodium polyacrylate and 0.00001 parts by mass of anionic sodium polyacrylate.

次に、専用の金型を用意し、型開きした金型の下型に、製造した一枚の複合シートＢと粉末の樹脂組成物とを順次インサートし、その後、粉末の樹脂組成物にスクレーバを接触させて水平に移動させ、複合シートＢの表面上で粉末の樹脂組成物をスクレーバで均一にならして平坦化した。   Next, a dedicated die is prepared, and the manufactured composite sheet B and the powdered resin composition are sequentially inserted into the lower die of the opened die, and then the powdered resin composition is scraped. Were contacted with each other and moved horizontally, and the powdery resin composition was leveled on the surface of the composite sheet B by a scraper to be flattened.

樹脂組成物は、低融点樹脂を１０質量部、及び粒子含有導電材を９０質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表３に示すように、平均粒子径が１８μｍで融点が１４６℃のポリプロピレン樹脂〔製品名：フロービーズ 住友精化株式会社製〕を用いた。また、粒子含有導電材は、表３に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕を用いた。
その他の部分については実施例１と同様とし、２５ｃｍ×２５ｃｍ、厚さ０．３０〜０．３３ｍｍのレドックスフロー電池用双極板を製造した。 The resin composition was 20.8 g of a composition containing 10 parts by mass of the low melting point resin and 90 parts by mass of the particle-containing conductive material. As the low melting point resin of this resin composition, as shown in Table 3, a polypropylene resin having an average particle diameter of 18 μm and a melting point of 146 ° C. [Product name: Flow beads manufactured by Sumitomo Seika Chemicals Co., Ltd.] was used. As the particle-containing conductive material, as shown in Table 3, artificial graphite particles having an average particle diameter of 45 μm [product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.] were used.
Other parts were the same as in Example 1, and a bipolar plate for a redox flow battery having a size of 25 cm × 25 cm and a thickness of 0.30 to 0.33 mm was manufactured.

〔実施例１０〕
レドックスフロー電池用双極板の複合シートについては、実施例９の複合シートＢをそのまま採用した。
次に、専用の金型を用意してそのキャビティ面に一定量の離型剤〔製品名：ダイフリーＧＡ７５００ ダイキン工業株式会社製〕を塗布し、型開きした金型の下型に、製造した一枚の複合シートＡと粉末の樹脂組成物とを順次インサートし、その後、粉末の樹脂組成物にスクレーバを接触させて水平に移動させ、複合シートの表面上で粉末の樹脂組成物をスクレーバで均一にならして平坦化した。 [Example 10]
As the bipolar sheet composite sheet for a redox flow battery, the composite sheet B of Example 9 was used as it was.
Next, a dedicated mold was prepared, and a certain amount of a release agent [Product name: Die-free GA7500 manufactured by Daikin Industries, Ltd.] was applied to the cavity surface of the mold to manufacture a lower mold of the mold which was opened. One composite sheet A and the powdered resin composition were sequentially inserted, and then the powdered resin composition was brought into contact with the scraper to move horizontally, and the powdered resin composition was moved on the surface of the composite sheet by the scraper. It was made uniform and flattened.

樹脂組成物は、低融点樹脂を１０質量部、及び粒子含有導電材を９０質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表３に示すように、平均粒子径が２０μｍで融点が１０９℃の低密度ポリエチレン樹脂〔製品名：ＬＤＰＥ ＵＦ１．５Ｎ 住友精化株式会社製〕に変更した。また、粒子含有導電材は、表３に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕とした。
その他の部分については実施例１と同様とし、２５ｃｍ×２５ｃｍ、厚さ０．３０〜０．３３ｍｍのレドックスフロー電池用双極板を製造した。 The resin composition was 20.8 g of a composition containing 10 parts by mass of the low melting point resin and 90 parts by mass of the particle-containing conductive material. As shown in Table 3, the low melting point resin of this resin composition was changed to a low density polyethylene resin having an average particle size of 20 μm and a melting point of 109 ° C. (product name: LDPE UF1.5N manufactured by Sumitomo Seika Chemicals Ltd.). . As shown in Table 3, the particle-containing conductive material was artificial graphite particles having an average particle diameter of 45 μm (product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.).
Other parts were the same as in Example 1, and a bipolar plate for a redox flow battery having a size of 25 cm × 25 cm and a thickness of 0.30 to 0.33 mm was manufactured.

〔実施例１１〕
基本的には実施例９と同様だが、樹脂組成物を変更した。すなわち、樹脂組成物は、低融点樹脂を３５質量部、及び粒子含有導電材を６５質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表３に示すように、平均粒子径が１８μｍで融点が１４６℃のポリプロピレン樹脂〔製品名：フロービーズ 住友精化株式会社製〕に変更した。また、粒子含有導電材は、表３に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕に変更した。 [Example 11]
Basically the same as in Example 9, but the resin composition was changed. That is, the resin composition was 20.8 g of a composition containing 35 parts by mass of the low melting point resin and 65 parts by mass of the particle-containing conductive material. As shown in Table 3, the low melting point resin of this resin composition was changed to polypropylene resin having an average particle diameter of 18 μm and a melting point of 146 ° C. [Product name: FlowBeads manufactured by Sumitomo Seika Chemicals Co., Ltd.]. As shown in Table 3, the particle-containing conductive material was changed to artificial graphite particles having an average particle diameter of 45 μm (product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.).

〔実施例１２〕
先ず、レドックスフロー電池用双極板の複合シートを製造すべく、繊維樹脂として、ポリプロピレン繊維１５質量部、導電材の粒子状導電材として、人造黒鉛粒子７０質量部、導電材の繊維状導電材として、炭素繊維１０質量部、及びアラミド系樹脂繊維として、アラミド繊維５質量部を用意（表１参照）し、これらを水中で混合分散して固形分３％のスラリーを作製した。 [Example 12]
First, in order to manufacture a composite sheet of a bipolar plate for a redox flow battery, as a fiber resin, 15 parts by mass of polypropylene fiber, as a particulate conductive material of a conductive material, 70 parts by mass of artificial graphite particles, as a fibrous conductive material of a conductive material. , 10 parts by mass of carbon fiber, and 5 parts by mass of aramid fiber as aramid resin fiber were prepared (see Table 1), and these were mixed and dispersed in water to prepare a slurry having a solid content of 3%.

ポリプロピレン繊維〔製品名：Ｊ１０５Ｈ 株式会社プライムポリマー製〕は、融点１６６℃、平均繊維径２０μｍ、平均繊維長５ｍｍの長さにカットした短繊維を使用した。また、人造黒鉛粒子は、平均粒子径が４５μｍのＪＳＧ‐７５Ｓ〔製品名 富士黒鉛工業株式会社製〕に変更した。炭素繊維は、炭素繊維トレカ〔（登録商標） 東レ株式会社製〕のカットファイバーＴ００８‐００３（繊維φ７μｍ、カット長３ｍｍ）をそのまま使用した。また、アラミド繊維は、長さ３ｍｍのケプラーカットファイバー〔製品名：Ｋｅｖｌａｒ（登録商標） 東レ・デュポン株式会社製〕とした。   As the polypropylene fiber [product name: J105H made by Prime Polymer Co., Ltd.], a short fiber cut into a length of 166 ° C., an average fiber diameter of 20 μm and an average fiber length of 5 mm was used. Further, the artificial graphite particles were changed to JSG-75S [product name: Fuji Graphite Industry Co., Ltd.] having an average particle diameter of 45 μm. As the carbon fiber, the cut fiber T008-003 (fiber φ7 μm, cut length 3 mm) of carbon fiber trading card [registered trademark (Toray Co., Ltd.)] was used as it was. The aramid fiber was a 3 mm long Kepler-cut fiber [Product name: Kevlar (registered trademark) manufactured by Toray DuPont Co., Ltd.].

スラリーを作製したら、このスラリーに凝集剤を添加して混合物を調製し、この混合物をメッシュ構造の２５ｃｍ角のシート機により抄紙シートに形成し、抄紙シートを１００℃に加熱したプレス機にセットして約２００ｋｇ／ｃｍ２の圧力で約５分間加圧加熱し、その後、抄紙シートを乾燥させて水分を除去することにより、ポリプロピレン繊維に膨張化黒鉛粒子と炭素繊維とが均一に分散して絡んだ厚さ０．７ｍｍ，坪量１００ｇ／ｍ２の複合シートＣを必要数製造した。凝集剤は、カチオン系ポリアクリル酸ソーダ０．００１質量部と、アニオン系ポリアクリル酸ソーダ０．００００１質量部とからなる添加物とした。 After preparing the slurry, a coagulant is added to the slurry to prepare a mixture, the mixture is formed into a papermaking sheet by a 25 cm square sheet machine having a mesh structure, and the papermaking sheet is set in a press machine heated to 100 ° C. By heating at a pressure of about 200 kg / cm 2 for about 5 minutes, and then drying the papermaking sheet to remove water, so that the expanded graphite particles and the carbon fibers are uniformly dispersed and entangled in the polypropylene fibers. A required number of composite sheets C having a thickness of 0.7 mm and a basis weight of 100 g / m 2 were manufactured. The coagulant was an additive composed of 0.001 parts by mass of cationic sodium polyacrylate and 0.00001 parts by mass of anionic sodium polyacrylate.

次に、専用の金型を用意し、型開きした金型の下型に、製造した一枚の複合シートＣと粉末の樹脂組成物とを順次インサートし、その後、粉末の樹脂組成物にスクレーバを接触させて水平に移動させ、複合シートＣの表面上で粉末の樹脂組成物をスクレーバで均一にならして平坦化した。   Next, a dedicated mold is prepared, and the manufactured composite sheet C and the powdered resin composition are sequentially inserted into the lower mold of the mold, and then the powdered resin composition is scraped. Were contacted with each other and moved horizontally, and the powdery resin composition was leveled on the surface of the composite sheet C by a scraper to be flattened.

樹脂組成物は、低融点樹脂を５質量部、及び粒子含有導電材を９５質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表３に示すように、平均粒子径が１８μｍで融点が１４６℃のポリプロピレン樹脂〔製品名：フロービーズ 住友精化株式会社製〕を用いた。また、粒子含有導電材は、表３に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕を用いた。
その他の部分については実施例１と同様とし、２５ｃｍ×２５ｃｍ、厚さ０．３０〜０．３３ｍｍのレドックスフロー電池用双極板を製造した。 The resin composition was 20.8 g of a composition containing 5 parts by mass of the low melting point resin and 95 parts by mass of the particle-containing conductive material. As the low melting point resin of this resin composition, as shown in Table 3, a polypropylene resin having an average particle diameter of 18 μm and a melting point of 146 ° C. [Product name: Flow beads manufactured by Sumitomo Seika Chemicals Co., Ltd.] was used. As the particle-containing conductive material, as shown in Table 3, artificial graphite particles having an average particle diameter of 45 μm [product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.] were used.
Other parts were the same as in Example 1, and a bipolar plate for a redox flow battery having a size of 25 cm × 25 cm and a thickness of 0.30 to 0.33 mm was manufactured.

〔実施例１３〕
先ず、レドックスフロー電池用双極板の複合シートについては、実施例１２の複合シートＣをそのまま採用した。
次に、専用の金型を用意し、型開きした金型の下型に、製造した一枚の複合シートＣと粉末の樹脂組成物とを順次インサートし、その後、粉末の樹脂組成物にスクレーバを接触させて水平に移動させ、複合シートの表面上で粉末の樹脂組成物をスクレーバで均一にならして平坦化した。 [Example 13]
First, as the composite sheet of the bipolar plate for the redox flow battery, the composite sheet C of Example 12 was used as it was.
Next, a dedicated mold is prepared, and the manufactured composite sheet C and the powdered resin composition are sequentially inserted into the lower mold of the mold, and then the powdered resin composition is scraped. Were contacted with each other and moved horizontally, and the powdery resin composition was leveled on the surface of the composite sheet by a scraper to be flattened.

樹脂組成物は、低融点樹脂を５質量部、及び粒子含有導電材を９５質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表３に示すように、平均粒子径が２０μｍで融点が１０９℃の低密度ポリエチレン樹脂〔製品名：ＬＤＰＥ ＵＦ１．５Ｎ 住友精化株式会社製〕に変更した。また、粒子含有導電材は、表３に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕に変更した。
その他の部分については実施例１と同様であり、２５ｃｍ×２５ｃｍ、厚さ０．３０〜０．３３ｍｍのレドックスフロー電池用双極板を製造した。 The resin composition was 20.8 g of a composition containing 5 parts by mass of the low melting point resin and 95 parts by mass of the particle-containing conductive material. As shown in Table 3, the low melting point resin of this resin composition was changed to a low density polyethylene resin having an average particle size of 20 μm and a melting point of 109 ° C. (product name: LDPE UF1.5N manufactured by Sumitomo Seika Chemicals Ltd.). . As shown in Table 3, the particle-containing conductive material was changed to artificial graphite particles having an average particle diameter of 45 μm (product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.).
Other parts were the same as in Example 1, and a bipolar plate for a redox flow battery having a size of 25 cm × 25 cm and a thickness of 0.30 to 0.33 mm was manufactured.

〔実施例１４〕
レドックスフロー電池用双極板の複合シートを製造すべく、繊維樹脂として、ポリエチレン繊維２５質量部、導電材の粒子状導電材として、膨張化黒鉛粒子６０質量部、導電材の繊維状導電材として、炭素繊維１０質量部、及びアラミド系樹脂繊維として、アラミド繊維５質量部を用意（表１参照）し、これらを水中で混合分散して固形分３％のスラリーを作製した。 [Example 14]
In order to manufacture a composite sheet of bipolar plates for redox flow batteries, as a fiber resin, 25 parts by mass of polyethylene fiber, as a particulate conductive material of a conductive material, 60 parts by mass of expanded graphite particles, as a fibrous conductive material of a conductive material, 10 parts by mass of carbon fibers and 5 parts by mass of aramid fibers were prepared as aramid resin fibers (see Table 1), and these were mixed and dispersed in water to prepare a slurry having a solid content of 3%.

ポリエチレン繊維〔製品名：フローセンＭ１３１５２Ｎ 住友精化株式会社製〕は、融点１２０℃、平均繊維径１８μｍ、平均繊維長５ｍｍの長さにカットした短繊維を使用した。また、膨張化黒鉛粒子は、平均粒子径が２００μｍのＢＳＰ‐２００Ａ〔製品名 富士黒鉛工業株式会社製〕に変更した。炭素繊維は、炭素繊維トレカ〔（登録商標） 東レ株式会社製〕のカットファイバーＴ００８‐００３（繊維φ７μｍ、カット長３ｍｍ）をそのまま使用した。また、アラミド繊維は、長さ３ｍｍのケプラーカットファイバー〔製品名：Ｋｅｖｌａｒ（登録商標） 東レ・デュポン株式会社製〕とした。   Polyethylene fiber [Product name: FLOWCEN M13152N manufactured by Sumitomo Seika Kabushiki Kaisha] was a short fiber cut to a melting point of 120 ° C., an average fiber diameter of 18 μm, and an average fiber length of 5 mm. Further, the expanded graphite particles were changed to BSP-200A [product name: manufactured by Fuji Graphite Industry Co., Ltd.] having an average particle diameter of 200 μm. As the carbon fiber, the cut fiber T008-003 (fiber φ7 μm, cut length 3 mm) of carbon fiber trading card [registered trademark (Toray Co., Ltd.)] was used as it was. The aramid fiber was a 3 mm long Kepler-cut fiber [Product name: Kevlar (registered trademark) manufactured by Toray DuPont Co., Ltd.].

スラリーを作製したら、このスラリーに凝集剤を添加して混合物を調製し、この混合物をメッシュ構造の２５ｃｍ角のシート機により抄紙シートに形成し、抄紙シートを８０℃に加熱したプレス機にセットして約２００ｋｇ／ｃｍ２の圧力で約１０分間加圧加熱し、その後、抄紙シートを乾燥させて水分を除去することにより、ポリプロピレン繊維に膨張化黒鉛粒子と炭素繊維とが均一に分散して絡んだ厚さ０．７ｍｍ，坪量１００ｇ／ｍ２の複合シートＤを必要数製造した。凝集剤は、カチオン系ポリアクリル酸ソーダ０．００１質量部と、アニオン系ポリアクリル酸ソーダ０．００００１質量部とからなる添加物とした。 After preparing the slurry, a coagulant is added to the slurry to prepare a mixture, the mixture is formed into a papermaking sheet by a 25 cm square sheet machine having a mesh structure, and the papermaking sheet is set in a press machine heated to 80 ° C. And heated at a pressure of about 200 kg / cm 2 for about 10 minutes, and then the papermaking sheet is dried to remove water, whereby the expanded graphite particles and the carbon fibers are uniformly dispersed and entangled in the polypropylene fibers. A required number of composite sheets D having a thickness of 0.7 mm and a basis weight of 100 g / m 2 were manufactured. The coagulant was an additive composed of 0.001 parts by mass of cationic sodium polyacrylate and 0.00001 parts by mass of anionic sodium polyacrylate.

次に、専用の金型を用意してそのキャビティ面に一定量の離型剤〔製品名：ダイフリーＧＡ７５００ ダイキン工業株式会社製〕を塗布し、型開きした金型の下型に、製造した一枚の複合シートＤと粉末の樹脂組成物とを順次インサートし、その後、粉末の樹脂組成物にスクレーバを接触させて水平に移動させ、複合シートＤの表面上で粉末の樹脂組成物をスクレーバで均一にならして平坦化した。   Next, a dedicated mold was prepared, and a certain amount of a release agent [Product name: Die-free GA7500 manufactured by Daikin Industries, Ltd.] was applied to the cavity surface of the mold to manufacture a lower mold of the mold which was opened. A single composite sheet D and a powdered resin composition are sequentially inserted, and then a scraper is brought into contact with the powdered resin composition and moved horizontally, so that the powdered resin composition is scraped on the surface of the composite sheet D. It was made uniform and flattened.

樹脂組成物は、低融点樹脂を１０質量部、及び粒子含有導電材を９０質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表３に示すように、平均粒子径が２０μｍで融点が１０９℃の低密度ポリエチレン樹脂〔製品名：ＬＤＰＥ ＵＦ１．５Ｎ 住友精化株式会社製〕を用いた。また、粒子含有導電材は、表３に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕を用いた。
その他の部分については実施例１と同様であり、２５ｃｍ×２５ｃｍ、厚さ０．３０〜０．３３ｍｍのレドックスフロー電池用双極板を製造した。 The resin composition was 20.8 g of a composition containing 10 parts by mass of the low melting point resin and 90 parts by mass of the particle-containing conductive material. As the low melting point resin of this resin composition, as shown in Table 3, a low density polyethylene resin having an average particle size of 20 μm and a melting point of 109 ° C. [product name: LDPE UF1.5N manufactured by Sumitomo Seika Chemicals Co., Ltd.] was used. . As the particle-containing conductive material, as shown in Table 3, artificial graphite particles having an average particle diameter of 45 μm [product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.] were used.
Other parts were the same as in Example 1, and a bipolar plate for a redox flow battery having a size of 25 cm × 25 cm and a thickness of 0.30 to 0.33 mm was manufactured.

〔比較例１〕
先ず、レドックスフロー電池用双極板の複合シートを製造すべく、繊維樹脂として、ポリプロピレン繊維２５質量部、導電材の粒子状導電材として、膨張化黒鉛粒子６０質量部、導電材の繊維状導電材として、炭素繊維１０質量部、及びアラミド系樹脂繊維として、アラミド繊維５質量部を用意（表１参照）し、これらを水中で混合分散して固形分３％のスラリーを作製した。 [Comparative Example 1]
First, in order to manufacture a bipolar sheet composite sheet for a redox flow battery, 25 parts by mass of polypropylene fiber as a fiber resin, 60 parts by mass of expanded graphite particles as a particulate conductive material of a conductive material, and a fibrous conductive material of a conductive material. As 10 parts by mass of carbon fiber and 5 parts by mass of aramid fiber as aramid resin fiber were prepared (see Table 1), these were mixed and dispersed in water to prepare a slurry having a solid content of 3%.

ポリプロピレン繊維〔製品名：Ｊ１０５Ｈ 株式会社プライムポリマー製〕は、融点１６６℃、平均繊維径２０μｍ、平均繊維長５ｍｍの長さにカットした短繊維を使用した。また、膨張化黒鉛粒子は、平均粒子径が２００μｍのＢＳＰ‐２００Ａ〔製品名 富士黒鉛工業株式会社製〕を使用した。炭素繊維は、炭素繊維トレカ〔（登録商標） 東レ株式会社製〕のカットファイバーＴ００８‐００３（繊維φ７μｍ、カット長３ｍｍ）を使用した。また、アラミド繊維は、長さ３ｍｍのケプラーカットファイバー〔製品名：Ｋｅｖｌａｒ（登録商標） 東レ・デュポン株式会社製〕とした。   As the polypropylene fiber [product name: J105H made by Prime Polymer Co., Ltd.], a short fiber cut into a length of 166 ° C., an average fiber diameter of 20 μm and an average fiber length of 5 mm was used. The expanded graphite particles used were BSP-200A (product name: Fuji Graphite Industry Co., Ltd.) having an average particle diameter of 200 μm. As the carbon fiber, a cut fiber T008-003 (fiber φ7 μm, cut length 3 mm) of carbon fiber trading card [registered trademark (Toray Co., Ltd.)] was used. The aramid fiber was a 3 mm long Kepler-cut fiber [Product name: Kevlar (registered trademark) manufactured by Toray DuPont Co., Ltd.].

固形分３％のスラリーを作製したら、このスラリーに凝集剤を添加して混合物を調製し、この混合物をメッシュ構造の２５ｃｍ角のシート機により抄紙シートに形成し、抄紙シートを１００℃に加熱したプレス機にセットして約２００ｋｇ／ｃｍ２の圧力で約５分間加圧加熱し、その後、抄紙シートを乾燥させて水分を除去することにより、ポリプロピレン繊維に膨張化黒鉛粒子と炭素繊維とが均一に分散して絡んだ厚さ０．７ｍｍ，坪量１００ｇ／ｍ２の複合シートＡを必要数製造した。凝集剤は、カチオン系ポリアクリル酸ソーダ０．００１質量部と、アニオン系ポリアクリル酸ソーダ０．００００１質量部とからなる添加物とした。 When a slurry having a solid content of 3% was prepared, a coagulant was added to the slurry to prepare a mixture, the mixture was formed into a papermaking sheet by a 25 cm square sheet machine having a mesh structure, and the papermaking sheet was heated to 100 ° C. It is set in a press and heated at a pressure of about 200 kg / cm 2 for about 5 minutes, and then the papermaking sheet is dried to remove water, so that the expanded graphite particles and the carbon fibers are uniformly dispersed in the polypropylene fiber. The required number of composite sheets A having a thickness of 0.7 mm and a basis weight of 100 g / m 2 dispersed and entangled with each other were manufactured. The coagulant was an additive composed of 0.001 parts by mass of cationic sodium polyacrylate and 0.00001 parts by mass of anionic sodium polyacrylate.

次に、専用の金型を用意し、型開きした金型の下型に、製造した一枚の複合シートＡと粉末の樹脂組成物とを順次インサートし、その後、粉末の樹脂組成物にスクレーバを接触させて水平に移動させ、複合シートＡの表面上で粉末の樹脂組成物をスクレーバで均一にならして平坦化した。   Next, a dedicated mold is prepared, and the manufactured composite sheet A and the powdered resin composition are sequentially inserted into the lower mold of the mold, and then the powdered resin composition is scraped. Were contacted with each other and moved horizontally, and the powdered resin composition was leveled on the surface of the composite sheet A by a scraper to be flattened.

樹脂組成物は、低融点樹脂を省略し、粒子含有導電材を１００質量部のみを含む組成物２０．８ｇとした。粒子含有導電材は、表４に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕を用いた。   The low melting point resin was omitted from the resin composition, and 20.8 g of a composition containing only 100 parts by mass of the particle-containing conductive material was used. As the particle-containing conductive material, as shown in Table 4, artificial graphite particles having an average particle diameter of 45 μm [product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.] were used.

次いで、樹脂組成物に残り一枚の複合シートＡを重ねることにより、相対向する複数枚の複合シートＡの間に粉末の樹脂組成物を挟み、残り一枚の複合シートＡに金型の上型を搭載するとともに、２２０℃の温度に設定した金型を２０ＭＰａで強く型締めして加圧加熱し、上下の熱板の温度が３０℃の冷却用の圧縮成形機に直ちに移載し、金型の温度が８０℃以下になるまで２０ＭＰａの圧力で加圧冷却することにより、レドックスフロー電池用双極板を圧縮成形した。   Then, by stacking the remaining composite sheet A on the resin composition, the powdery resin composition is sandwiched between the plurality of composite sheets A facing each other, and the remaining composite sheet A is placed on the mold. While mounting the mold, the mold set at a temperature of 220 ° C. is strongly clamped at 20 MPa, heated under pressure, and immediately transferred to a compression molding machine for cooling, where the temperature of the upper and lower hot plates is 30 ° C. The bipolar plate for a redox flow battery was compression-molded by pressurizing and cooling at a pressure of 20 MPa until the temperature of the mold became 80 ° C. or lower.

レドックスフロー電池用双極板を圧縮成形したら、金型からレドックスフロー電池用双極板を脱型し、２５ｃｍ×２５ｃｍ、厚さ０．３０〜０．３３ｍｍのレドックスフロー電池用双極板を製造した。   After the compression molding of the redox flow battery bipolar plate, the redox flow battery bipolar plate was removed from the mold to produce a redox flow battery bipolar plate having a size of 25 cm × 25 cm and a thickness of 0.30 to 0.33 mm.

次に、製造したレドックスフロー電池用双極板の機械的強度である初期の引張強度、ｐＨ＝−０．６８の５価硫酸バナジウム水溶液中にレドックスフロー電池用双極板を１００時間浸漬した後の引張強度をそれぞれ測定して表７に記載した。また、レドックスフロー電池用双極板の導電性として、面方向の体積抵抗値と厚み方向の体積抵抗値とをそれぞれ測定して表７に記載した。レドックスフロー電池用双極板の割れ発生の有無（柔軟性や強度）についても、試験を実施してその結果を表７に記載した。   Next, the tensile strength after the bipolar plate for a redox flow battery was immersed for 100 hours in an aqueous solution of vanadium pentavalent sulfate having an initial tensile strength, pH = -0.68, which is the mechanical strength of the manufactured bipolar plate for a redox flow battery. The respective strengths were measured and listed in Table 7. Further, as the conductivity of the bipolar plate for a redox flow battery, the volume resistance value in the plane direction and the volume resistance value in the thickness direction were measured and listed in Table 7. The presence / absence of cracking (flexibility and strength) of the bipolar plate for redox flow battery was also tested, and the results are shown in Table 7.

〔比較例２〕
レドックスフロー電池用双極板の複合シートについては、実施例１４の複合シートＤに変更した。
次に、専用の金型を用意し、型開きした金型の下型に、製造した一枚の複合シートＤと粉末の樹脂組成物とを順次インサートし、その後、粉末の樹脂組成物にスクレーバを接触させて水平に移動させ、複合シートの表面上で粉末の樹脂組成物をスクレーバで均一にならして平坦化した。 [Comparative Example 2]
The composite sheet of the bipolar plate for the redox flow battery was changed to the composite sheet D of Example 14.
Next, a dedicated mold is prepared, and the manufactured composite sheet D and the powder resin composition are sequentially inserted into the lower mold of the mold opened, and then the powder resin composition is scraped. Were contacted with each other and moved horizontally, and the powdery resin composition was leveled on the surface of the composite sheet by a scraper to be flattened.

樹脂組成物は、低融点樹脂を１０質量部、及び粒子含有導電材を９０質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表４に示すように、平均粒子径が１８μｍで融点が１４６℃のポリプロピレン樹脂〔製品名：フロービーズ 住友精化株式会社製〕を採用した。また、粒子含有導電材は、表４に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕を用いた。
その他の部分については実施例１と同様とし、２５ｃｍ×２５ｃｍ、厚さ０．３０〜０．３３ｍｍのレドックスフロー電池用双極板を製造した。 The resin composition was 20.8 g of a composition containing 10 parts by mass of the low melting point resin and 90 parts by mass of the particle-containing conductive material. As the low melting point resin of this resin composition, as shown in Table 4, a polypropylene resin having an average particle diameter of 18 μm and a melting point of 146 ° C. [product name: Flow Beads manufactured by Sumitomo Seika Chemicals Co., Ltd.] was adopted. As the particle-containing conductive material, as shown in Table 4, artificial graphite particles having an average particle diameter of 45 μm [product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.] were used.
Other parts were the same as in Example 1, and a bipolar plate for a redox flow battery having a size of 25 cm × 25 cm and a thickness of 0.30 to 0.33 mm was manufactured.

〔比較例３〕
先ず、レドックスフロー電池用双極板の複合シートについては、実施例１４の複合シートＤを採用した。また、樹脂組成物を変更し、低融点樹脂を２０質量部、及び粒子含有導電材を８０質量部含む樹脂組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表２に示すように、平均粒子径が１８μｍで融点が１４６℃のポリプロピレン樹脂〔製品名：フロービーズ 住友精化株式会社製〕を用いた。また、粒子含有導電材は、表４に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕を用いた。 [Comparative Example 3]
First, the composite sheet D of Example 14 was adopted as the composite sheet of the bipolar plate for the redox flow battery. The resin composition was changed to 20.8 g of a resin composition containing 20 parts by mass of the low melting point resin and 80 parts by mass of the particle-containing conductive material. As the low melting point resin of this resin composition, as shown in Table 2, a polypropylene resin having an average particle diameter of 18 μm and a melting point of 146 ° C. [Product name: Flow beads manufactured by Sumitomo Seika Chemicals Co., Ltd.] was used. As the particle-containing conductive material, as shown in Table 4, artificial graphite particles having an average particle diameter of 45 μm [product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.] were used.

その他の部分については実施例１と同様とし、２５ｃｍ×２５ｃｍ、厚さ０．３０〜０．３３ｍｍのレドックスフロー電池用双極板を製造した。   Other parts were the same as in Example 1, and a bipolar plate for a redox flow battery having a size of 25 cm × 25 cm and a thickness of 0.30 to 0.33 mm was manufactured.

〔比較例４〕
レドックスフロー電池用双極板の複合シートについては、実施例１４の複合シートＤを採用した。また、樹脂組成物を変更し、低融点樹脂を２０質量部、及び粒子含有導電材を８０質量部含む樹脂組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表４に示すように、融点が１３５℃の高密度ポリエチレン樹脂〔製品名：ＨＤＰＥ１７００Ｊ 株式会社プライムポリマー製〕を冷凍粉砕した後、３２メッシュの篩を通過した高密度ポリエチレン樹脂を使用した。また、粒子含有導電材は、表４に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕を使用した。 [Comparative Example 4]
The composite sheet D of Example 14 was adopted as the composite sheet of the bipolar plate for the redox flow battery. The resin composition was changed to 20.8 g of a resin composition containing 20 parts by mass of the low melting point resin and 80 parts by mass of the particle-containing conductive material. As shown in Table 4, the low melting point resin of this resin composition was obtained by freeze-grinding a high-density polyethylene resin having a melting point of 135 ° C. (product name: HDPE1700J made by Prime Polymer Co., Ltd.) and then passing through a 32 mesh sieve. High density polyethylene resin was used. As the particle-containing conductive material, as shown in Table 4, artificial graphite particles having an average particle diameter of 45 μm [product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.] were used.

〔比較例５〕
レドックスフロー電池用双極板の複合シートを製造すべく、繊維樹脂として、ポリエチレン繊維２５質量部、導電材の粒子状導電材として、膨張化黒鉛粒子６０質量部、導電材の繊維状導電材として、炭素繊維１０質量部、及びアラミド系樹脂繊維として、アラミド繊維５質量部を用意（表１参照）し、これらを水中で混合分散して固形分３％のスラリーを作製した。 [Comparative Example 5]
In order to manufacture a composite sheet of bipolar plates for redox flow batteries, as a fiber resin, 25 parts by mass of polyethylene fiber, as a particulate conductive material of a conductive material, 60 parts by mass of expanded graphite particles, as a fibrous conductive material of a conductive material, 10 parts by mass of carbon fibers and 5 parts by mass of aramid fibers were prepared as aramid resin fibers (see Table 1), and these were mixed and dispersed in water to prepare a slurry having a solid content of 3%.

ポリエチレン繊維〔製品名：ＬＪ８０３ 日本ポリエチレン株式会社製〕は、融点１０９℃、平均繊維径１８μｍ、平均繊維長５ｍｍの長さにカットした短繊維を使用した。また、膨張化黒鉛粒子は、平均粒子径が２００μｍのＢＳＰ‐２００Ａ〔製品名 富士黒鉛工業株式会社製〕を使用した。炭素繊維は、炭素繊維トレカ〔（登録商標） 東レ株式会社製〕のカットファイバーＴ００８‐００３（繊維φ７μｍ、カット長３ｍｍ）を使用した。また、アラミド繊維は、長さ３ｍｍのケプラーカットファイバー〔製品名：Ｋｅｖｌａｒ（登録商標） 東レ・デュポン株式会社製〕とした。   Polyethylene fiber [Product name: LJ803 manufactured by Nippon Polyethylene Co., Ltd.] was a short fiber cut to a melting point of 109 ° C., an average fiber diameter of 18 μm, and an average fiber length of 5 mm. The expanded graphite particles used were BSP-200A (product name: Fuji Graphite Industry Co., Ltd.) having an average particle diameter of 200 μm. As the carbon fiber, a cut fiber T008-003 (fiber φ7 μm, cut length 3 mm) of carbon fiber trading card [registered trademark (Toray Co., Ltd.)] was used. The aramid fiber was a 3 mm long Kepler-cut fiber [Product name: Kevlar (registered trademark) manufactured by Toray DuPont Co., Ltd.].

固形分３％のスラリーを作製したら、このスラリーに凝集剤を添加して混合物を調製し、この混合物をメッシュ構造の２５ｃｍ角のシート機により抄紙シートに形成し、抄紙シートを８０℃に加熱したプレス機にセットして約２００ｋｇ／ｃｍ２の圧力で約１０分間加圧加熱し、その後、抄紙シートを乾燥させて水分を除去することにより、ポリプロピレン繊維に膨張化黒鉛粒子と炭素繊維とが均一に分散して絡んだ厚さ０．７ｍｍ，坪量１００ｇ／ｍ２の複合シートＥを必要数製造した。凝集剤は、カチオン系ポリアクリル酸ソーダ０．００１質量部と、アニオン系ポリアクリル酸ソーダ０．００００１質量部とからなる添加物とした。 When a slurry having a solid content of 3% was prepared, a coagulant was added to the slurry to prepare a mixture, and the mixture was formed into a papermaking sheet by a 25 cm square sheet machine having a mesh structure, and the papermaking sheet was heated to 80 ° C. It is set in a press and heated at a pressure of about 200 kg / cm 2 for about 10 minutes, and then the papermaking sheet is dried to remove water, so that the expanded graphite particles and the carbon fibers are uniformly dispersed in the polypropylene fiber. The required number of composite sheets E having a thickness of 0.7 mm and a basis weight of 100 g / m 2 dispersed and entangled with each other were manufactured. The coagulant was an additive composed of 0.001 parts by mass of cationic sodium polyacrylate and 0.00001 parts by mass of anionic sodium polyacrylate.

次に、専用の金型を用意し、型開きした金型の下型に、製造した一枚の複合シートＥと粉末の樹脂組成物とを順次インサートし、その後、粉末の樹脂組成物にスクレーバを接触させて水平に移動させ、複合シートＥの表面上で粉末の樹脂組成物をスクレーバで均一にならして平坦化した。   Next, a dedicated die is prepared, and the manufactured composite sheet E and the powdered resin composition are sequentially inserted into the lower die of the opened die, and then the powdered resin composition is scraped. Were contacted with each other and moved horizontally, and the powdery resin composition was leveled on the surface of the composite sheet E by a scraper to be flattened.

樹脂組成物は、低融点樹脂を１０質量部、及び粒子含有導電材を９０質量部含む組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表４に示すように、平均粒子径が１８μｍで融点が１４６℃のポリプロピレン樹脂〔製品名：フロービーズ 住友精化株式会社製〕を使用した。また、粒子含有導電材は、表２に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕を使用した。
その他の部分については実施例１と同様とし、２５ｃｍ×２５ｃｍ、厚さ０．３０〜０．３３ｍｍのレドックスフロー電池用双極板を製造した。 The resin composition was 20.8 g of a composition containing 10 parts by mass of the low melting point resin and 90 parts by mass of the particle-containing conductive material. As the low melting point resin of this resin composition, as shown in Table 4, a polypropylene resin having an average particle diameter of 18 μm and a melting point of 146 ° C. [Product name: FlowBeads manufactured by Sumitomo Seika Chemicals Co., Ltd.] was used. As the particle-containing conductive material, as shown in Table 2, artificial graphite particles having an average particle diameter of 45 μm (product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.) were used.
Other parts were the same as in Example 1, and a bipolar plate for a redox flow battery having a size of 25 cm × 25 cm and a thickness of 0.30 to 0.33 mm was manufactured.

〔比較例６〕
先ず、レドックスフロー電池用双極板の複合シートについては、比較例５の複合シートＥを採用した。また、樹脂組成物を変更し、低融点樹脂を１０質量部、及び粒子含有導電材を９０質量部含む樹脂組成物２０．８ｇとした。この樹脂組成物の低融点樹脂は、表４に示すように、融点が１３５℃の高密度ポリエチレン樹脂〔製品名：ＨＤＰＥ１７００Ｊ 株式会社プライムポリマー製〕を冷凍粉砕した後、３２メッシュの篩を通過した高密度ポリエチレン樹脂を使用した。また、粒子含有導電材は、表４に示すように、平均粒子径が４５μｍの人造黒鉛粒子〔製品名：ＪＳＧ‐７５Ｓ 富士黒鉛工業株式会社製〕を用いた。 [Comparative Example 6]
First, the composite sheet E of Comparative Example 5 was adopted as the composite sheet of the bipolar plate for the redox flow battery. Moreover, the resin composition was changed to 20.8 g of a resin composition containing 10 parts by mass of the low melting point resin and 90 parts by mass of the particle-containing conductive material. As shown in Table 4, the low melting point resin of this resin composition was obtained by freeze-grinding a high-density polyethylene resin having a melting point of 135 ° C. (product name: HDPE1700J made by Prime Polymer Co., Ltd.) and then passing through a 32 mesh sieve. High density polyethylene resin was used. As the particle-containing conductive material, as shown in Table 4, artificial graphite particles having an average particle diameter of 45 μm [product name: JSG-75S manufactured by Fuji Graphite Industry Co., Ltd.] were used.

〔比較例７〕
先ず、レドックスフロー電池用双極板の複合シートを製造すべく、繊維樹脂として、ポリプロピレン繊維５質量部、導電材の粒子状導電材として、膨張化黒鉛粒子８０質量部、導電材の繊維状導電材として、炭素繊維１０質量部、及びアラミド系樹脂繊維として、アラミド繊維５質量部を用意（表１参照）し、これらを水中で混合分散して固形分３％のスラリーを作製した。 [Comparative Example 7]
First, in order to manufacture a bipolar sheet composite sheet for a redox flow battery, 5 parts by mass of polypropylene fiber as a fiber resin, 80 parts by mass of expanded graphite particles as a particulate conductive material of a conductive material, and a fibrous conductive material of a conductive material. As 10 parts by mass of carbon fiber and 5 parts by mass of aramid fiber as aramid resin fiber were prepared (see Table 1), these were mixed and dispersed in water to prepare a slurry having a solid content of 3%.

ポリプロピレン繊維〔製品名：Ｊ１０５Ｈ 株式会社プライムポリマー製〕は、融点１６６℃、平均繊維径２０μｍ、平均繊維長５ｍｍの長さにカットした短繊維を使用した。また、膨張化黒鉛粒子は、平均粒子径が２００μｍのＢＳＰ‐２００Ａ〔製品名 富士黒鉛工業株式会社製〕を使用した。炭素繊維は、炭素繊維トレカ〔（登録商標） 東レ株式会社製〕のカットファイバーＴ００８‐００３（繊維φ７μｍ、カット長３ｍｍ）を使用した。また、アラミド繊維は、長さ３ｍｍのケプラーカットファイバー〔製品名：Ｋｅｖｌａｒ（登録商標） 東レ・デュポン株式会社製〕とした。   As the polypropylene fiber [product name: J105H made by Prime Polymer Co., Ltd.], a short fiber cut into a length of 166 ° C., an average fiber diameter of 20 μm and an average fiber length of 5 mm was used. The expanded graphite particles used were BSP-200A (product name: Fuji Graphite Industry Co., Ltd.) having an average particle diameter of 200 μm. As the carbon fiber, a cut fiber T008-003 (fiber φ7 μm, cut length 3 mm) of carbon fiber trading card [registered trademark (Toray Co., Ltd.)] was used. The aramid fiber was a 3 mm long Kepler-cut fiber [Product name: Kevlar (registered trademark) manufactured by Toray DuPont Co., Ltd.].

固形分３％のスラリーを作製したら、このスラリーに凝集剤を添加して混合物を調製し、この混合物をメッシュ構造の２５ｃｍ角のシート機により抄紙シートに形成し、抄紙シートを１００℃に加熱したプレス機にセットして約２００ｋｇ／ｃｍ２の圧力で約５分間加圧加熱し、その後、抄紙シートを乾燥させて水分を除去することにより、ポリプロピレン繊維に膨張化黒鉛粒子と炭素繊維とが均一に分散して絡んだ厚さ０．７ｍｍ，坪量５００ｇ／ｍ２の複合シートＦを必要数製造した。凝集剤は、カチオン系ポリアクリル酸ソーダ０．００１質量部と、アニオン系ポリアクリル酸ソーダ０．００００１質量部とからなる添加物とした。 When a slurry having a solid content of 3% was prepared, a coagulant was added to the slurry to prepare a mixture, the mixture was formed into a papermaking sheet by a 25 cm square sheet machine having a mesh structure, and the papermaking sheet was heated to 100 ° C. It is set in a press and heated at a pressure of about 200 kg / cm 2 for about 5 minutes, and then the papermaking sheet is dried to remove water, so that the expanded graphite particles and the carbon fibers are uniformly dispersed in the polypropylene fiber. The required number of composite sheets F having a thickness of 0.7 mm and a basis weight of 500 g / m 2 dispersed and entangled with each other were manufactured. The coagulant was an additive composed of 0.001 parts by mass of cationic sodium polyacrylate and 0.00001 parts by mass of anionic sodium polyacrylate.

次に、専用の金型を用意し、型開きした金型の下型に、製造した一対の複合シートＦを重ねてインサートし、樹脂組成物を省略した。
複合シートＦを重ねてインサートしたら、この複合シートＦに金型の上型を搭載するとともに、２２０℃の温度に設定した金型を２０ＭＰａで強く型締めして加圧加熱し、上下の熱板の温度が３０℃の冷却用の圧縮成形機に直ちに移載し、金型の温度が８０℃以下になるまで２０ＭＰａの圧力で加圧冷却することにより、レドックスフロー電池用双極板を圧縮成形した。 Next, a dedicated mold was prepared, and the pair of composite sheets F produced were overlaid and inserted into the lower mold of the mold that was opened, and the resin composition was omitted.
When the composite sheet F is stacked and inserted, the upper die of the die is mounted on the composite sheet F, and the die set to a temperature of 220 ° C. is strongly clamped at 20 MPa to heat under pressure, and the upper and lower hot plates are attached. Was immediately transferred to a compression molding machine for cooling at a temperature of 30 ° C., and pressure-cooled at a pressure of 20 MPa until the temperature of the mold became 80 ° C. or less to compression-mold a bipolar plate for a redox flow battery. .

レドックスフロー電池用双極板を圧縮成形したら、金型からレドックスフロー電池用双極板を脱型し、２５ｃｍ×２５ｃｍ、厚さ０．２２〜０．３５ｍｍの厚みムラの大きいレドックスフロー電池用双極板を製造した。製造したレドックスフロー電池用双極板の一部には、穴や破れている箇所が発見された。   After compression molding the bipolar plate for redox flow battery, the bipolar plate for redox flow battery is removed from the mold, and a bipolar plate for redox flow battery with 25 cm x 25 cm and a thickness of 0.22 to 0.35 mm is formed. Manufactured. Holes and broken parts were found in some of the manufactured bipolar plates for redox flow batteries.

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〔評 価〕
各実施例のレドックスフロー電池用双極板は、初期の引張強度、ｐＨ＝−０．６８の５価硫酸バナジウム水溶液中にレドックスフロー電池用双極板を１００時間浸漬した後の引張強度、面方向の体積抵抗値、厚み方向の体積抵抗値、割れ発生の有無について、良好な結果を得ることができた。特に、実施例９、１０、１２のレドックスフロー電池用双極板は、厚み方向の体積抵抗値に関し、優れた結果を得ることができた。 [Evaluation]
The bipolar plate for a redox flow battery of each example has initial tensile strength, tensile strength after dipping the bipolar plate for a redox flow battery in an aqueous solution of pentavalent vanadium sulfate having a pH of -0.68 for 100 hours, Good results were obtained regarding the volume resistance value, the volume resistance value in the thickness direction, and the presence or absence of cracks. In particular, the bipolar plates for redox flow batteries of Examples 9, 10, and 12 were able to obtain excellent results regarding the volume resistance value in the thickness direction.

これに対し、比較例のレドックスフロー電池用双極板は、初期の引張強度、ｐＨ＝−０．６８の５価硫酸バナジウム水溶液中にレドックスフロー電池用双極板を１００時間浸漬した後の引張強度、面方向の体積抵抗値、厚み方向の体積抵抗値、割れ発生の有無に関し、満足する結果を得ることができなかった。特に、比較例１、５、７のレドックスフロー電池用双極板は、割れが発生し、実用性に深刻な疑義が生じた。   On the other hand, the redox flow battery bipolar plate of the comparative example had an initial tensile strength, and a tensile strength after the redox flow battery bipolar plate was immersed in an aqueous pentavalent vanadium sulfate solution having a pH of -0.68 for 100 hours, Satisfactory results could not be obtained regarding the volume resistance in the plane direction, the volume resistance in the thickness direction, and the presence or absence of cracks. In particular, the bipolar plates for redox flow batteries of Comparative Examples 1, 5, and 7 were cracked, and serious doubts were put on their practicality.

本発明に係るレドックスフロー電池用双極板及びその製造方法は、レドックスフロー電池の製造分野で使用される。   The bipolar plate for a redox flow battery and the method for manufacturing the same according to the present invention are used in the field of manufacturing a redox flow battery.

１ レドックスフロー電池用双極板
２ 複合シート
３ 樹脂組成物 1 Bipolar plate for redox flow battery 2 Composite sheet 3 Resin composition

Claims (13)

対向する複数の複合シートの間に樹脂組成物が挟まれるレドックスフロー電池用双極板であって、
複合シートは、少なくともポリオレフィン系樹脂繊維を含有する繊維樹脂と、この繊維樹脂よりも優れた導電性の導電材とを含み、この導電材が粒子状導電材と繊維状導電材とを含有しており、
樹脂組成物は、融点が複合シートの繊維樹脂の融点よりも５℃以上低く、かつ融点がレドックスフロー電池の作動温度以上の低融点樹脂と、少なくとも粒子状導電材を有する粒子含有導電材とを含み、
複数の複合シートと樹脂組成物とが溶着して一体化されることを特徴とするレドックスフロー電池用双極板。 A bipolar plate for a redox flow battery, in which a resin composition is sandwiched between a plurality of facing composite sheets,
The composite sheet includes a fiber resin containing at least a polyolefin-based resin fiber, and a conductive material having a conductivity higher than that of the fiber resin, and the conductive material contains a particulate conductive material and a fibrous conductive material. Cage,
The resin composition comprises a low melting point resin having a melting point of 5 ° C. or more lower than that of the fiber resin of the composite sheet and a melting point of not less than the operating temperature of the redox flow battery, and a particle-containing conductive material having at least a particulate conductive material. Including,
A bipolar plate for a redox flow battery, wherein a plurality of composite sheets and a resin composition are fused and integrated. 複合シートの繊維樹脂は、アラミド系樹脂繊維を含有する請求項１記載のレドックスフロー電池用双極板。   The bipolar plate for a redox flow battery according to claim 1, wherein the fiber resin of the composite sheet contains an aramid resin fiber. 複合シートの繊維樹脂は、平均繊維長が０．５ｍｍ以上８０ｍｍ以下である請求項１又は２記載のレドックスフロー電池用双極板。   The bipolar resin plate for a redox flow battery according to claim 1 or 2, wherein the fiber resin of the composite sheet has an average fiber length of 0.5 mm or more and 80 mm or less. 複合シートの繊維樹脂のポリオレフィン系樹脂繊維は、ポリプロピレン系樹脂繊維とポリエチレン系樹脂繊維の少なくともいずれか一方である請求項１、２、又は３記載のレドックスフロー電池用双極板。   The bipolar plate for a redox flow battery according to claim 1, 2 or 3, wherein the polyolefin resin fiber of the fiber resin of the composite sheet is at least one of polypropylene resin fiber and polyethylene resin fiber. 複合シートの導電材は、粒子状導電材が黒鉛粒子であり、繊維状導電材が炭素繊維である請求項１ないし４のいずれかに記載のレドックスフロー電池用双極板。   The bipolar plate for a redox flow battery according to any one of claims 1 to 4, wherein the conductive material of the composite sheet is graphite particles and the fibrous conductive material is carbon fiber. 複合シートの導電材の粒子状導電材は、平均粒子径が３μｍ以上５００μｍ以下の膨張化黒鉛粒子と人造黒鉛粒子の少なくともいずれか一方である請求項１ないし５のいずれかに記載のレドックスフロー電池用双極板。   The redox flow battery according to any one of claims 1 to 5, wherein the particulate conductive material of the conductive material of the composite sheet is at least one of expanded graphite particles having an average particle diameter of 3 µm or more and 500 µm or less and artificial graphite particles. Bipolar plate. 樹脂組成物は、低融点樹脂を３質量部以上４０質量部以下、及び粒子含有導電材を６０質量部以上９７質量部以下含む請求項１ないし６のいずれかに記載のレドックスフロー電池用双極板。   7. The bipolar plate for a redox flow battery according to claim 1, wherein the resin composition contains a low melting point resin in an amount of 3 parts by mass or more and 40 parts by mass or less and a particle-containing conductive material in an amount of 60 parts by mass or more and 97 parts by mass or less. . 樹脂組成物の低融点樹脂は、熱可塑性樹脂である請求項１ないし７のいずれかに記載のレドックスフロー電池用双極板。   The bipolar plate for a redox flow battery according to any one of claims 1 to 7, wherein the low melting point resin of the resin composition is a thermoplastic resin. 樹脂組成物の低融点樹脂は、平均粒子径が１０μｍ以上５００μｍ以下の粒子状のポリプロピレン系樹脂あるいはポリエチレン系樹脂である請求項１ないし８のいずれかに記載のレドックスフロー電池用双極板。   The bipolar plate for a redox flow battery according to claim 1, wherein the low melting point resin of the resin composition is a particulate polypropylene resin or polyethylene resin having an average particle diameter of 10 μm or more and 500 μm or less. 樹脂組成物の粒子含有導電材の粒子状導電材は、平均粒子径が１μｍ以上２００μｍ以下の黒鉛粒子である請求項１ないし９のいずれかに記載のレドックスフロー電池用双極板。   The bipolar plate for a redox flow battery according to claim 1, wherein the particulate conductive material of the particle-containing conductive material of the resin composition is graphite particles having an average particle diameter of 1 μm or more and 200 μm or less. 請求項１ないし１０のいずれかに記載のレドックスフロー電池用双極板の製造方法であって、
金型に、複数の複合シートと樹脂組成物とをインサートして複数の複合シートの間に樹脂組成物を挟み、金型を型締めして加圧加熱することにより、レドックスフロー電池用双極板を成形することを特徴とするレドックスフロー電池用双極板の製造方法。 A method for manufacturing a bipolar plate for a redox flow battery according to any one of claims 1 to 10, comprising:
A bipolar plate for a redox flow battery by inserting a plurality of composite sheets and a resin composition into a mold, sandwiching the resin composition between the plurality of composite sheets, clamping the mold and heating under pressure. A method for producing a bipolar plate for a redox flow battery, which comprises molding. 金型に、複数の複合シートの一部と樹脂組成物とをインサートし、樹脂組成物に複数の複合シートの残部を重ねることにより、対向する複数の複合シートの間に樹脂組成物を挟む請求項１１記載のレドックスフロー電池用双極板の製造方法。   Inserting a resin composition between a plurality of opposing composite sheets by inserting a part of the plurality of composite sheets and the resin composition into a mold and stacking the rest of the plurality of composite sheets on the resin composition. Item 12. A method for manufacturing a bipolar plate for a redox flow battery according to item 11. 金型に、樹脂組成物と複数の複合シートの一部とをインサートするとともに、金型を型締めして加圧加熱することにより、積層中間体を成形し、金型から積層中間体を脱型して反転し、この積層中間体を金型にインサートしてその樹脂組成物を露出させ、その後、積層中間体の樹脂組成物に複数の複合シートの残部を重ねることで、積層中間体の複合シートと複合シートとの間に樹脂組成物を挟む請求項１１記載のレドックスフロー電池用双極板の製造方法。   While inserting the resin composition and a part of the plurality of composite sheets into the mold, the mold is clamped and heated under pressure to form a laminated intermediate, and the laminated intermediate is removed from the mold. Mold and invert, insert this laminated intermediate into a mold to expose the resin composition, and then stack the rest of the plurality of composite sheets on the resin composition of the laminated intermediate to obtain the laminated intermediate. The method for producing a bipolar plate for a redox flow battery according to claim 11, wherein the resin composition is sandwiched between the composite sheets.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021215030A1 (en) * 2019-04-24 2021-10-28 住友電気工業株式会社 Bipolar plate, battery cell, cell stack, and redox flow battery

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021215030A1 (en) * 2019-04-24 2021-10-28 住友電気工業株式会社 Bipolar plate, battery cell, cell stack, and redox flow battery

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