JP2007176070A - Electroconductive composite membrane, manufacturing method of the same, and separator for fuel cell - Google Patents
Electroconductive composite membrane, manufacturing method of the same, and separator for fuel cell Download PDFInfo
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
Description
本発明は、導電性複合膜、その製造方法及び燃料電池用セパレータに関する。 The present invention relates to a conductive composite membrane, a method for producing the same, and a fuel cell separator.
従来、導電性を有する膜を作製するため、様々な方法が検討されている。そして、導電性を有する膜は、例えば、燃料電池用途等に適用される。 Conventionally, various methods have been studied for producing a conductive film. And the film | membrane which has electroconductivity is applied to a fuel cell use etc., for example.
一般に、燃料電池は、燃料極と空気極との二つの電極が電解質を挟み込み、さらに、それぞれの電極の外側にセパレータを配して構成されている。このような燃料電池において、セパレータは、集電体としての役割と水素または酸素を供給する通路形成材としての役割とを有するものであるため、導電性と水素及び酸素に対する耐透過性が求められる。 In general, a fuel cell is configured such that two electrodes, a fuel electrode and an air electrode, sandwich an electrolyte, and a separator is disposed outside each electrode. In such a fuel cell, since the separator has a role as a current collector and a role as a passage forming material for supplying hydrogen or oxygen, conductivity and permeation resistance to hydrogen and oxygen are required. .
特に、燃料電池の中でも固体高分子型燃料電池（ＰＥＦＣ）においては、電解質として固体高分子電解質膜を使用しており、この固体高分子電解質膜はスルホン酸基を備え、水素イオンを選択的に透過するものであるため、ＰＥＦＣの内部では硫酸の雰囲気となっている。したがって、ＰＥＦＣに使用するセパレータには、上記の性能に加え、硫酸に対する耐食性が求められ、これらの特性を満たすものとしてカーボンが使用されている。 In particular, in a polymer electrolyte fuel cell (PEFC) among fuel cells, a solid polymer electrolyte membrane is used as an electrolyte. This solid polymer electrolyte membrane has a sulfonic acid group and selectively selects hydrogen ions. Since it permeates, it has a sulfuric acid atmosphere inside the PEFC. Therefore, in addition to the above performance, the separator used for PEFC is required to have corrosion resistance against sulfuric acid, and carbon is used to satisfy these characteristics.
従来、セパレータにカーボンを使用する場合には、固形のカーボン材を機械加工したものを使用するため、セパレータは高価なものとなっていた。
このような課題に対しては、これまで、燃料電池用セパレータとして、ステンレス鋼の基板に、カーボン系粒子が分散した塗膜を形成させ、加熱処理して塗膜成分を分解・消失させることにより、カーボン系粒子の結合層とその結合層の表面に付着するカーボン系粒子とを形成させたもの（例えば、特許文献１参照）、ステンレス鋼の基板にグラファイト粉末とカーボンブラックとの導電材を含む導電性塗膜を形成させたもの(例えば、特許文献２参照)、鉄、アルミニウム等の金属層に、カーボンブラック等の導電材と導電材を固定するための樹脂結着材とで構成される被覆層を形成させたもの（例えば、特許文献３参照）等が提案されている。
Conventionally, when carbon is used for the separator, a machined solid carbon material is used, so that the separator is expensive.
For such problems, as a fuel cell separator, a coating film in which carbon-based particles are dispersed is formed on a stainless steel substrate, and heat treatment is performed to decompose and eliminate coating film components. A carbon-based particle bonding layer and carbon-based particles adhering to the surface of the bonding layer (see, for example, Patent Document 1), a stainless steel substrate containing a conductive material of graphite powder and carbon black Consists of a conductive coating film (for example, see Patent Document 2), a conductive material such as carbon black and a resin binder for fixing the conductive material to a metal layer such as iron or aluminum. The thing in which the coating layer was formed (for example, refer patent document 3) etc. is proposed.
しかし、前記従来のステンレス鋼の基板に、カーボン系粒子の結合層とその結合層の表面に付着するカーボン系粒子とを形成させたものでは、カーボン系粒子同士の間に塗膜成分が消失した分の隙間が生じる場合があり、導電性が不十分であった。また、固体高分子型燃料電池用のセパレータとして使用する場合には、カーボン系粒子の隙間を通じて、ステンレス鋼が硫酸に曝される虞があり、耐食性の面でも問題があった。 However, in the conventional stainless steel substrate in which the carbon-based particle bonding layer and the carbon-based particles adhering to the surface of the bonding layer are formed, the coating film component disappears between the carbon-based particles. Minute gaps may occur, and the conductivity is insufficient. Further, when used as a separator for a polymer electrolyte fuel cell, there is a possibility that stainless steel may be exposed to sulfuric acid through a gap between carbon-based particles, and there is a problem in terms of corrosion resistance.
また、ステンレス鋼の基板に導電材を含む導電性塗膜を形成させたものや、金属層に、導電材と樹脂結着材とで構成される被覆層を形成させたものでは、導電材同士の間に樹脂が存在し、導通が妨げられるため、導電性が不十分であるという問題があった。 In addition, in the case where a conductive coating film containing a conductive material is formed on a stainless steel substrate, or in the case where a coating layer composed of a conductive material and a resin binder is formed on a metal layer, the conductive materials There is a problem in that the resin is present between the two, and conduction is hindered, so that the conductivity is insufficient.
本発明は上記問題に鑑み案出されたものであり、燃料電池用途等に適用可能な高い導電性を有する導電性複合膜及びその製造方法を提供することを目的とする。
さらには、上記導電性に加え、耐食性を有し、固体高分子型燃料電池等に適用できる燃料電池用セパレータを提供することを目的とする。
The present invention has been devised in view of the above problems, and an object thereof is to provide a conductive composite film having high conductivity applicable to fuel cell applications and the like, and a method for producing the same.
Furthermore, it aims at providing the separator for fuel cells which has corrosion resistance in addition to the said electroconductivity, and can be applied to a polymer electrolyte fuel cell etc.
上記目的を達成するための本発明に係る導電性複合膜の第１特徴構成は、樹脂粒子と、当該樹脂粒子の表面に付着した導電性粒子とを有する複合粒子が、当該複合粒子の表面の樹脂同士が溶融接着されて、積層構造を形成してある点にある。 In order to achieve the above object, the first characteristic configuration of the conductive composite film according to the present invention is that a composite particle having resin particles and conductive particles attached to the surface of the resin particles is formed on the surface of the composite particles. The resin is melt-bonded to form a laminated structure.
つまり、この構成によれば、表面に導電性粒子を有する複合粒子が、粒子形状を保ちつつ積層構造を形成しているため、表面の導電性粒子同士が接触して、高い導電性を有する導電性複合膜とすることができる。
また、複合粒子による積層構造を有しているため、ピンホール等ができ難い緻密な構造の導電性複合膜とすることができる。
In other words, according to this configuration, the composite particles having conductive particles on the surface form a laminated structure while maintaining the particle shape. Composite film.
Further, since it has a laminated structure of composite particles, a conductive composite film having a dense structure in which pinholes and the like are difficult to be formed can be obtained.
本発明に係る導電性複合膜の第２特徴構成は、前記導電性粒子の粒子径が１５〜１５０ｎｍであり、前記樹脂粒子の粒子径が０．３〜２．５μｍであって、前記複合粒子中の前記導電性粒子の体積割合が２０〜６０％である点にある。 A second characteristic configuration of the conductive composite film according to the present invention is that the conductive particles have a particle diameter of 15 to 150 nm, the resin particles have a particle diameter of 0.3 to 2.5 μm, and the composite particles The volume ratio of the conductive particles is 20 to 60%.
つまり、この構成によれば、導電性粒子の粒子径を１５〜１５０ｎｍ、樹脂の粒子径を０．３〜２．５μｍとし、複合粒子中の前記導電性粒子の体積割合を２０〜６０％として、樹脂粒子の表面に対する導電性粒子の付着態様を、導電性粒子同士が接触し易いように特定できるため、良好な導電性を確保できる好適な条件が設定できる。 That is, according to this configuration, the particle diameter of the conductive particles is 15 to 150 nm, the particle diameter of the resin is 0.3 to 2.5 μm, and the volume ratio of the conductive particles in the composite particles is 20 to 60%. Moreover, since the adhesion mode of the conductive particles with respect to the surface of the resin particles can be specified so that the conductive particles can easily come into contact with each other, it is possible to set suitable conditions that can ensure good conductivity.
本発明に係る導電性複合膜の第３特徴構成は、前記導電性粒子は、カーボンブラックである点にある。 A third characteristic configuration of the conductive composite film according to the present invention is that the conductive particles are carbon black.
つまり、この構成によれば、カーボンブラックは良好な導電性を有するため、導電性複合膜の導電性をより高くすることができる。 That is, according to this structure, since carbon black has favorable electroconductivity, the electroconductivity of an electroconductive composite film can be made higher.
本発明に係る導電性複合膜の第４特徴構成は、前記カーボンブラックは、中空シェル状のカーボンブラックである点にある。 A fourth characteristic configuration of the conductive composite film according to the present invention is that the carbon black is a hollow shell carbon black.
つまり、この構成によれば、中空シェル状のカーボンブラックは、高い比表面積を有し、他のカーボンブラックに比べて少量の添加量で同等の導電性を付与することができる。このため、導電性粒子として使用することにより、複合膜に占める導電性粒子の重量割合を小さくすることができ、樹脂の物性に与える影響を小さくすることができる。 That is, according to this configuration, the hollow shell-shaped carbon black has a high specific surface area, and can impart equivalent conductivity with a small amount of addition compared to other carbon blacks. For this reason, by using as electroconductive particle, the weight ratio of electroconductive particle which occupies for a composite film can be made small, and the influence which it has on the physical property of resin can be made small.
本発明に係る導電性複合膜の第５特徴構成は、前記樹脂粒子は、フッ素系樹脂、イミド系樹脂、シリコン系樹脂、ポリエーテル系樹脂から選ばれる少なくとも１種の樹脂からなる点にある。 A fifth characteristic configuration of the conductive composite film according to the present invention is that the resin particles are made of at least one resin selected from a fluorine resin, an imide resin, a silicon resin, and a polyether resin.
つまり、この構成によれば、酸に対して耐食性を有する導電性複合膜の好適な樹脂粒子材料を得ることができる。 That is, according to this configuration, it is possible to obtain a suitable resin particle material for a conductive composite film having corrosion resistance against acid.
本発明に係る導電性複合膜の第６特徴構成は、金属基板の上に形成された点にある。 The 6th characteristic structure of the electroconductive composite film which concerns on this invention exists in the point formed on the metal substrate.
つまり、この構成によれば、導電性複合膜を金属基板の上に形成することにより、導電性複合膜の強度を高めることができる。
また、耐食性を有し、ピンホール等のない緻密な構造を有する導電性複合膜を金属基板の上に形成した場合には、導電性複合膜自身が腐食されないだけでなく、金属基板の保護膜として金属基板が腐食されるのを防止することもできるため、高い導電性及び耐食性を有する金属基板とすることができる。
That is, according to this configuration, the strength of the conductive composite film can be increased by forming the conductive composite film on the metal substrate.
In addition, when a conductive composite film having a corrosion resistance and a dense structure without pinholes is formed on a metal substrate, the conductive composite film itself is not corroded, but a protective film for the metal substrate. Since it can also prevent that a metal substrate is corroded, it can be set as a metal substrate which has high electroconductivity and corrosion resistance.
本発明に係る導電性複合膜の第７特徴構成は、前記金属基板は、表面に不動態皮膜防止用の金属層を有する点にある。 A seventh characteristic configuration of the conductive composite film according to the present invention is that the metal substrate has a metal layer for preventing a passive film on the surface.
つまり、この構成によれば、不動態皮膜防止用金属層が、金属基板の表面に不動態皮膜（酸化皮膜）が形成されることを抑制することができる。このため、基板の表面の接触抵抗を低減させることができる。したがって、金属層の上に形成された導電性複合膜と基板との間の電荷の移動を妨げることがなく、高い導電性を確保することができる。 That is, according to this configuration, the metal layer for preventing a passive film can suppress the formation of a passive film (oxide film) on the surface of the metal substrate. For this reason, the contact resistance of the surface of a board | substrate can be reduced. Therefore, high conductivity can be ensured without hindering the movement of charges between the conductive composite film formed on the metal layer and the substrate.
本発明に係る導電性複合膜の第８特徴構成は、前記金属基板は、前記金属層として、ニッケル、ニッケルと銀、ニッケルと金、銅のいずれかの層を形成したステンレス鋼の基板である点にある。 An eighth characteristic configuration of the conductive composite film according to the present invention is that the metal substrate is a stainless steel substrate in which any one layer of nickel, nickel and silver, nickel and gold, or copper is formed as the metal layer. In the point.
つまり、この構成によれば、安価で入手が容易なステンレス鋼の基板の表面にニッケル等の金属層が形成された不動態皮膜防止被膜付きの金属基板の好適な実施形態が得られる。 That is, according to this configuration, a preferred embodiment of a metal substrate with a passivation film preventing film in which a metal layer such as nickel is formed on the surface of a stainless steel substrate that is inexpensive and easily available can be obtained.
本発明に係る燃料電池用セパレータの特徴構成は、前記導電性複合膜を用いた点にある。 The characteristic configuration of the fuel cell separator according to the present invention is that the conductive composite film is used.
つまり、この構成によれば、高い導電性を有するため、燃料電池用セパレータに適用しても電池出力特性を低下させることはない。特に、導電性に加え、耐食性を有し、ピンホール等のない緻密な構造を有する導電性複合膜を用いる場合には、固体高分子型燃料電池（ＰＥＦＣ）のセパレータとして適用することができる。 That is, according to this structure, since it has high electroconductivity, even if it applies to the separator for fuel cells, a battery output characteristic will not be reduced. In particular, in the case of using a conductive composite film that has corrosion resistance and a dense structure with no pinholes in addition to conductivity, it can be applied as a separator for a polymer electrolyte fuel cell (PEFC).
本発明に係る導電性複合膜の製造方法の第１特徴構成は、樹脂が溶解した樹脂溶液と当該樹脂に対する貧溶媒との少なくとも一方に導電性粒子を分散させた後、前記樹脂溶液と前記貧溶媒とを混合して、樹脂粒子の表面に導電性粒子が付着した複合粒子を前記貧溶媒中に析出させる複合粒子作製工程と、当該複合粒子を所定形状に堆積させ、加熱して前記複合粒子の表面の樹脂同士を溶融接着させる製膜工程とを備える点にある。 The first characteristic configuration of the method for producing a conductive composite film according to the present invention is that after dispersing conductive particles in at least one of a resin solution in which a resin is dissolved and a poor solvent for the resin, the resin solution and the poor A composite particle preparation step of mixing a solvent and depositing composite particles having conductive particles attached to the surface of the resin particles in the poor solvent; depositing the composite particles in a predetermined shape; and heating to form the composite particles And a film-forming step of melt-bonding the resins on the surface of each other.
つまり、この構成によれば、樹脂溶液に溶解している樹脂が貧溶媒中で溶解度が低下して粒子化する過程で、分散された導電性粒子が生成樹脂粒子の表面に良好に存在する複合粒子を析出させることができ、さらに、当該樹脂粒子の表面に導電性粒子が付着した複合粒子の表面の樹脂同士を溶融接着させて複合膜を形成するため、複合粒子の表面の導電性粒子同士が接触し、導電性の高い導電性複合膜とすることができる。
また、複合粒子を所定形状に堆積させて複合膜を形成するため、ピンホール等ができ難い緻密な構造の導電性複合膜とすることができる。
In other words, according to this configuration, in the process in which the resin dissolved in the resin solution is reduced in solubility in a poor solvent to form particles, a composite in which dispersed conductive particles are present well on the surface of the generated resin particles In addition, the conductive particles on the surface of the composite particle can be deposited to form a composite film by melting and bonding the resin on the surface of the composite particle having conductive particles attached to the surface of the resin particle. Can be made into a conductive composite film having high conductivity.
In addition, since the composite film is formed by depositing the composite particles in a predetermined shape, a conductive composite film having a dense structure in which pinholes and the like are difficult to be formed can be obtained.
本発明に係る導電性複合膜の製造方法の第２特徴構成は、前記製膜工程では、前記複合粒子を析出させた前記貧溶媒の中に、少なくとも一方が導電性の基材となる正負一対の電極を配置し、前記正負一対の電極の間に電位差を与えて、前記複合粒子を電気泳動により前記基材の上に堆積させる点にある。 According to a second characteristic configuration of the method for producing a conductive composite film according to the present invention, in the film forming step, at least one of the positive and negative pairs in which the composite particles are precipitated is a conductive base material. The electrodes are arranged, a potential difference is applied between the pair of positive and negative electrodes, and the composite particles are deposited on the substrate by electrophoresis.
つまり、この構成によれば、基材の形状に関わらず、基材の表面に導電性複合膜を均一に形成させることができる。 That is, according to this configuration, the conductive composite film can be uniformly formed on the surface of the base material regardless of the shape of the base material.
本発明に係る導電性複合膜の製造方法の第３特徴構成は、前記基材として金属基材を使用する場合において、前記製膜工程の前に、前記金属基材の表面に不動態皮膜防止用の金属層を設ける点にある。 The third characteristic configuration of the method for producing a conductive composite film according to the present invention is that when a metal substrate is used as the substrate, the passivation film is prevented from being formed on the surface of the metal substrate before the film forming step. The point is to provide a metal layer.
つまり、この構成によれば、金属基材の表面に不動態皮膜が形成されることを防止し、金属基材の表面の接触抵抗を低減させることができる。 That is, according to this structure, it can prevent that a passive film is formed on the surface of a metal base material, and can reduce the contact resistance of the surface of a metal base material.
本発明に係る導電性複合膜は、樹脂粒子と、当該樹脂粒子の表面に付着した導電性粒子とを有する複合粒子が、当該複合粒子の表面の樹脂同士が溶融接着されて、積層構造を形成してあるものである。これにより、表面に導電性粒子を有する複合粒子が、粒子形状を保ちつつ積層構造を形成しているため、表面の導電性粒子同士が接触して、高い導電性を有すると共に、ピンホール等ができ難い緻密な構造の複合膜とすることができる。このような導電性複合膜は、例えば、金属基板の上に形成させることにより、燃料電池用のセパレータ等、燃料電池用途に適用することができる。なお、本発明において、「複合粒子の表面の樹脂同士が溶融接着されて」とは、複合粒子が表面に導電性粒子を有する形態を保って、樹脂同士が溶融接着されることであり、厳密に複合粒子の表面のみの樹脂が溶融接着されることに限定するものではない。 In the conductive composite film according to the present invention, a composite particle having resin particles and conductive particles attached to the surface of the resin particles is formed by laminating the resins on the surface of the composite particles to form a laminated structure. It is what is. Thereby, since the composite particles having conductive particles on the surface form a laminated structure while maintaining the particle shape, the conductive particles on the surface are in contact with each other and have high conductivity, and pinholes and the like It can be a complex film having a dense structure that is difficult to achieve. Such a conductive composite film can be applied to a fuel cell application such as a separator for a fuel cell by being formed on a metal substrate. In the present invention, “the resin on the surface of the composite particle is melt-bonded” means that the resin is melt-bonded while maintaining the form in which the composite particle has conductive particles on the surface. It is not limited that the resin only on the surface of the composite particles is melt bonded.
このような導電性複合膜では、前記導電性粒子の粒子径が１５〜１５０ｎｍであり、前記樹脂粒子の粒子径が０．３〜２．５μｍであって、前記複合粒子中の前記導電性粒子の体積割合が、２０〜６０％であるものが好ましい。すなわち、これにより、樹脂粒子の表面に対する導電性粒子の付着態様を、導電性粒子同士が接触し易いように特定できるため、良好な導電性を確保できる好適な条件が設定できる。このような観点からは、導電性粒子の粒子径は、２０〜１００ｎｍがより好ましく、３０〜５０ｎｍがさらに好ましい。また、樹脂粒子の粒子径としては、０．５〜１．５μｍがより好ましく、複合粒子中の導電性粒子の体積割合は、２０〜４０％がより好ましい。 In such a conductive composite film, the particle diameter of the conductive particles is 15 to 150 nm, the particle diameter of the resin particles is 0.3 to 2.5 μm, and the conductive particles in the composite particles The volume ratio is preferably 20 to 60%. That is, this allows the conductive particles to be attached to the surface of the resin particles in such a manner that the conductive particles can easily come into contact with each other, so that suitable conditions for ensuring good conductivity can be set. From such a viewpoint, the particle diameter of the conductive particles is more preferably 20 to 100 nm, and further preferably 30 to 50 nm. The particle diameter of the resin particles is more preferably 0.5 to 1.5 μm, and the volume ratio of the conductive particles in the composite particles is more preferably 20 to 40%.
本発明に係る導電性複合膜を構成する導電性粒子は、例えば、ケッチェンブラック（アクゾ ノーベル ケミカルズ社の登録商標）、アセチレンブラック、ファーネスブラック等のカーボンブラック及び、黒鉛等のカーボン系粒子や、カーボンナノファイバ、セラミックス系粒子、カーバイド系粒子、ナイトライド系粒子、ナノ金属粒子等を好ましく適用することができる。カーボンブラックは２０〜１０００ｎｍの一次粒子の凝集体であり、この一次粒子が構造欠陥の多い多層フラーレン構造を有することにより良好な導電性を示すため、好ましく適用できる。例えば、このようなカーボンブラックは、体積固有抵抗が１０１３〜１５Ω・ｃｍレベルの樹脂等に添加することにより、体積固有抵抗を１００〜１Ω・ｃｍレベルに下げることもできる。カーボンブラックの中でも、中空シェル状のカーボンブラックであるケッチェンブラックは、表１に示すように高い比表面積を有し、他のカーボンブラックに比べて少量の添加量で同等の導電性を付与することができるため特に好ましく、導電性粒子として使用することにより、複合膜に占める導電性粒子の重量割合を小さくすることができ、樹脂の物性に与える影響を小さくすることができる。 The conductive particles constituting the conductive composite film according to the present invention include, for example, ketjen black (registered trademark of Akzo Nobel Chemicals), carbon black such as acetylene black and furnace black, and carbon-based particles such as graphite, Carbon nanofibers, ceramic-based particles, carbide-based particles, nitride-based particles, nanometal particles, and the like can be preferably applied. Carbon black is an aggregate of primary particles of 20 to 1000 nm. Since the primary particles have a multi-layer fullerene structure with many structural defects, good conductivity can be applied. For example, such a carbon black can be reduced to a volume resistivity of 100-1 Ω · cm by adding it to a resin having a volume resistivity of 10 13-15 Ω · cm. Among carbon blacks, ketjen black, which is a hollow shell carbon black, has a high specific surface area as shown in Table 1 and imparts the same conductivity with a small amount of addition compared to other carbon blacks. It is particularly preferable because it can be used, and by using it as conductive particles, the weight ratio of the conductive particles in the composite film can be reduced, and the influence on the physical properties of the resin can be reduced.
本発明に係る導電性複合膜を構成する樹脂粒子は、特に限定されないが、表２、表３に示すような樹脂を使用することができ、複合膜の用途や後述する製造方法に応じて選択することができる。例えば、フッ素系樹脂、イミド系樹脂、シリコン系樹脂、ポリエーテル系樹脂から選ばれる少なくとも１種の樹脂を適用すれば、これらの樹脂は、酸に対する耐食性に優れるため、特に高い耐食性を有する導電性複合膜とすることができる。 The resin particles constituting the conductive composite film according to the present invention are not particularly limited, but resins as shown in Tables 2 and 3 can be used, and are selected according to the use of the composite film and the manufacturing method described later. can do. For example, if at least one resin selected from fluorine-based resins, imide-based resins, silicon-based resins, and polyether-based resins is applied, these resins have excellent corrosion resistance against acids, and therefore have a particularly high corrosion resistance. It can be a composite membrane.
このような導電性複合膜は、特に限定されないが、例えば、ステンレス鋼等の金属基板の上に形成させて用いることができる。導電性複合膜は、金属基板の上に形成することにより強度を高めることができる。また、耐食性を有し、ピンホール等のない緻密な構造を有する導電性複合膜を金属基板の上に形成すれば、導電性複合膜自身が腐食されないだけでなく、金属基板の保護膜として金属基板が腐食されるのを防止することもできるため、高い導電性及び耐食性を有する金属基板として使用することができる。 Such a conductive composite film is not particularly limited, and can be used by being formed on a metal substrate such as stainless steel. The strength of the conductive composite film can be increased by forming it on the metal substrate. Further, if a conductive composite film having a corrosion resistance and a dense structure without pinholes is formed on a metal substrate, the conductive composite film itself is not corroded, and a metal is used as a protective film for the metal substrate. Since the substrate can be prevented from being corroded, it can be used as a metal substrate having high conductivity and corrosion resistance.
また、金属基板は、表面に不動態皮膜防止用の金属層を有することが好ましい。これにより、不動態皮膜防止用金属層が、金属基板の表面に不動態皮膜が形成されることを抑制し、基板の表面の接触抵抗を低減させることができる。したがって、金属層の上に形成された導電性複合膜と基板との間の電荷の移動を妨げることがなく、高い導電性を確保することができる。金属層としては、特に限定はされないが、例えば、ステンレス鋼の基板には、Ｎｉ，Ｎｉ−Ａｇ，Ｎｉ−Ａｕ，Ｃｕ等の層を設けることが好ましい。 The metal substrate preferably has a metal layer for preventing a passive film on the surface. Thereby, the metal layer for passive film prevention can suppress that a passive film is formed on the surface of a metal substrate, and can reduce the contact resistance of the surface of a board | substrate. Therefore, high conductivity can be ensured without hindering the movement of charges between the conductive composite film formed on the metal layer and the substrate. Although it does not specifically limit as a metal layer, For example, it is preferable to provide layers, such as Ni, Ni-Ag, Ni-Au, Cu, on a stainless steel board | substrate.
このような金属基板の上に設けた導電性複合膜は、例えば、燃料電池用セパレータに適用することできる。導電性複合膜は高い導電性を有するため、燃料電池用セパレータに適用しても電池出力特性を低下させることはない。特に、耐食性を有し、ピンホール等のない緻密な構造を有する導電性複合膜を表面に形成させた金属基板の場合には、ＰＥＦＣ用のセパレータとして好ましく適用することができる。すなわち、ＰＥＦＣの動作環境は、ＰＥＦＣの触媒層に残留した白金の硫酸塩等が生成水に溶出することや、ＰＥＦＣの発電に伴って電解質膜（ＭＥＡ膜）のスルホン酸基が徐々に分解され硫酸を発生すること、生成水及び水蒸気が存在すること等により、酸性雰囲気となる。したがって、このような導電性複合膜であれば、このようなＰＥＦＣの動作環境においても、高い導電性を保ちつつ、金属基板が腐食されるのを防止することができる。なお、金属基板としてステンレス鋼の基板を使用すれば、安価なＰＥＦＣ用セパレータとして、より好ましく適用することができる。 The conductive composite film provided on such a metal substrate can be applied to, for example, a fuel cell separator. Since the conductive composite film has high conductivity, even if it is applied to a fuel cell separator, the battery output characteristics are not deteriorated. In particular, in the case of a metal substrate having a conductive composite film having a dense structure with corrosion resistance and no pinholes, it can be preferably applied as a separator for PEFC. In other words, the operating environment of PEFC is that platinum sulfate remaining in the catalyst layer of PEFC elutes into the generated water, and the sulfonic acid group of the electrolyte membrane (MEA membrane) is gradually decomposed along with the power generation of PEFC. Due to the generation of sulfuric acid, the presence of produced water and water vapor, etc., the atmosphere becomes acidic. Therefore, with such a conductive composite film, it is possible to prevent the metal substrate from being corroded while maintaining high conductivity even in such an operating environment of PEFC. In addition, if a stainless steel substrate is used as the metal substrate, it can be more preferably applied as an inexpensive PEFC separator.
本発明に係る導電性複合膜の製造方法は、例えば、樹脂が溶解した樹脂溶液と当該樹脂に対する貧溶媒との少なくとも一方に導電性粒子を分散させた後、前記樹脂溶液と前記貧溶媒とを混合して、樹脂粒子の表面に導電性粒子が付着した複合粒子を前記貧溶媒中に析出させる複合粒子作製工程と、当該複合粒子を所定形状に堆積させ、加熱して前記複合粒子の表面の樹脂同士を溶融接着させる製膜工程とを備えるものである。この方法によれば、樹脂溶液に溶解している樹脂が貧溶媒中で溶解度が低下して粒子化する過程で、分散された導電性粒子が生成樹脂粒子の表面に良好に存在する複合粒子を析出させることができる。また、この樹脂粒子の表面に導電性粒子が付着した複合粒子の表面の樹脂同士を溶融接着させて複合膜を形成するため、複合粒子の表面の導電性粒子同士が接触して、例えば、導電性粒子を導通可能な網目状に配することができ、導電性の高い導電性複合膜とすることができる。さらには、複合粒子を所定形状に堆積させて導電性複合膜を形成することにより、ピンホール等ができ難い緻密な構造とすることができる。 In the method for producing a conductive composite film according to the present invention, for example, after dispersing conductive particles in at least one of a resin solution in which a resin is dissolved and a poor solvent for the resin, the resin solution and the poor solvent are dispersed. A composite particle preparation step of mixing and precipitating composite particles having conductive particles attached to the surface of the resin particles in the poor solvent; and depositing the composite particles in a predetermined shape; And a film forming process for melting and bonding the resins together. According to this method, in the process in which the resin dissolved in the resin solution is reduced in solubility in a poor solvent to form particles, composite particles in which dispersed conductive particles are well present on the surface of the generated resin particles are obtained. It can be deposited. In addition, since the resin on the surface of the composite particle having the conductive particles attached to the surface of the resin particle is melt-bonded to form a composite film, the conductive particles on the surface of the composite particle come into contact with each other, for example, conductive The conductive particles can be arranged in a conductive mesh shape, and a highly conductive composite film can be obtained. Furthermore, by forming the conductive composite film by depositing the composite particles in a predetermined shape, it is possible to obtain a dense structure in which pinholes are difficult to form.
本発明において使用する複合粒子は、上述の複合粒子作製工程により作製することができる。具体的には、例えば、樹脂を溶剤に溶解させた樹脂溶液に、導電性粒子を適量添加して混合し、超音波分散等により導電性粒子を均一に分散させて分散液を調製し、この分散液を貧溶媒に注入することにより、導電性粒子を伴った樹脂粒子が析出して高均一度に分散する安定な懸濁液を作製することができる。また、複合粒子は、貧溶媒に、導電性粒子を適量添加して混合し、超音波分散等により導電性粒子を均一に分散させた後、この貧溶媒に樹脂を溶剤に溶解させた樹脂溶液を注入することによっても作製することができる。これらの方法によれば、樹脂粒子は導電性粒子を伴いながら析出するため、樹脂の表面に導電性粒子を付着させることができる。 The composite particles used in the present invention can be produced by the composite particle production process described above. Specifically, for example, an appropriate amount of conductive particles are added to a resin solution in which a resin is dissolved in a solvent and mixed, and the dispersion is performed by uniformly dispersing the conductive particles by ultrasonic dispersion or the like. By injecting the dispersion liquid into a poor solvent, it is possible to produce a stable suspension in which resin particles accompanied with conductive particles are precipitated and dispersed with high uniformity. The composite particle is a resin solution in which an appropriate amount of conductive particles are added to a poor solvent and mixed, and the conductive particles are uniformly dispersed by ultrasonic dispersion or the like, and then the resin is dissolved in the poor solvent. It can also be produced by injecting. According to these methods, since the resin particles are deposited with the conductive particles, the conductive particles can be attached to the surface of the resin.
本発明に使用する貧溶媒は、複合膜に使用する樹脂が溶解し難いものを選択すればよく、フッ素系樹脂に対しては、エタノール等の溶媒を使用することができる。また、樹脂を溶解させる溶剤としては、使用する樹脂に応じて溶解し易いものを選択することができ、例えば、フッ素系樹脂に対しては、表２に示すように、Ｎ−メチル−２−ピロリドン（ＮＭＰ）が好ましく使用することができる。なお、ＮＭＰは、溶解性に優れるだけでなく、毒性が小さく、引火点が比較的高いため安全性にも優れており、特に好ましい。 The poor solvent used in the present invention may be selected from those in which the resin used for the composite film is difficult to dissolve, and a solvent such as ethanol can be used for the fluororesin. As the solvent for dissolving the resin, a solvent that can be easily dissolved can be selected according to the resin to be used. For example, for a fluorine-based resin, as shown in Table 2, N-methyl-2- Pyrrolidone (NMP) can be preferably used. NMP is particularly preferable because it not only has excellent solubility but also has low toxicity and a relatively high flash point, so that it has excellent safety.
上記のように作製した複合粒子は、製膜工程において、例えば、電気泳動により、用途に応じた所定の形状に堆積させることができる。すなわち、複合粒子を導電性の基材等に堆積させる場合には、前記複合粒子を析出させた前記貧溶媒の中に、少なくとも一方が導電性の基材となる正負一対の電極を配置し、当該正負一対の電極の間に電位差を与えて、前記複合粒子を電気泳動により前記基材の上に堆積させる。この方法によれば、複雑形状物へのコーティングや、構造物の内側面へのコーティング等、基材の形状に関わらず、基材の表面に導電性複合膜を均一に形成させることができる。このため、表面に水素または酸素が通る溝が設けられている燃料電池用セパレータ等の金属基板を基材として、その上に導電性複合膜を形成させる場合にも好ましく適用することができる。この方法において使用する基材としては、導電性を有するものであれば電極として使用できるため、特に制限はないが、例えば、ステンレス鋼の基材は安価であるため、特に好ましく適用することができる。なお、電気泳動の条件は、製造する複合膜の種類、厚み等によって、数Ｖ〜数百Ｖの印加電圧で数十秒〜数時間の間行う等、任意に設定可能である。 The composite particles produced as described above can be deposited in a predetermined shape according to the application, for example, by electrophoresis in a film forming process. That is, when depositing composite particles on a conductive substrate or the like, a pair of positive and negative electrodes, at least one of which is a conductive substrate, is disposed in the poor solvent in which the composite particles are deposited, A potential difference is applied between the pair of positive and negative electrodes, and the composite particles are deposited on the substrate by electrophoresis. According to this method, the conductive composite film can be uniformly formed on the surface of the base material regardless of the shape of the base material, such as coating on a complicated shape or coating the inner surface of the structure. Therefore, the present invention can be preferably applied to the case where a conductive composite film is formed on a metal substrate such as a fuel cell separator having a groove through which hydrogen or oxygen passes on the surface. The base material used in this method is not particularly limited because it can be used as an electrode as long as it has conductivity. For example, a stainless steel base material is inexpensive and can be particularly preferably applied. . The electrophoresis conditions can be arbitrarily set, such as for several tens of seconds to several hours at an applied voltage of several V to several hundred V depending on the type and thickness of the composite film to be manufactured.
また、基材として金属基材を使用する場合においては、製膜工程の前に、金属基材の表面に不動態皮膜防止用の金属層を設けることもできる。これにより、金属基材の表面に不動態皮膜が形成されることを防止し、金属基材の表面の接触抵抗を低減させることができる。このため、例えば、基材として表面に上記不動態皮膜防止用の金属層を形成した金属基板を使用し、その上に導電性複合膜を形成させたものは、導電性に優れるため、燃料電池用セパレータに好ましく適用することができる。 Moreover, when using a metal base material as a base material, the metal layer for a passive film prevention can also be provided in the surface of a metal base material before a film forming process. Thereby, it can prevent that a passive film is formed on the surface of a metal base material, and can reduce the contact resistance of the surface of a metal base material. For this reason, for example, a metal substrate in which a metal layer for preventing a passive film on the surface is formed as a base material and a conductive composite film is formed thereon has excellent conductivity. It can preferably be applied to the separator.
金属層は、例えば、めっき、塗布、蒸着等の従来公知の方法により、金属基材の表面に設けることができる。なお、金属基材の表面に金属層を設ける場合には、金属基材の表面に形成されている不動態皮膜を予め研磨等により除去しておくとよい。 The metal layer can be provided on the surface of the metal substrate by a conventionally known method such as plating, coating, or vapor deposition. In addition, when providing a metal layer on the surface of a metal base material, it is good to remove the passive film currently formed in the surface of a metal base material by grinding | polishing etc. previously.
複合粒子は、塗布、印刷等によって堆積させることもできる。この場合、複合粒子を溶剤等によりペースト状にして、基材等に堆積させればよい。この方法であれば、導電性を有しない基材等にも複合粒子を堆積させることができる。また、複合粒子は、必ずしも基材等に堆積させる必要はなく、例えば、基材等を必要としない抄紙法等のろ過方式によっても堆積させることができる。 The composite particles can also be deposited by coating, printing or the like. In this case, the composite particles may be pasted with a solvent or the like and deposited on the base material. With this method, composite particles can be deposited on a non-conductive substrate or the like. The composite particles do not necessarily have to be deposited on a substrate or the like, and can be deposited by a filtration method such as a papermaking method that does not require a substrate or the like.
また、製膜工程においては、例えば、複合粒子を電気泳動により所定形状に堆積させて乾燥した膜の上に、再び電気泳動により複合粒子を堆積させる二次製膜法等のように、複合粒子を複数回に分けて堆積させることもできる。これにより、緻密な構造の導電性複合膜を形成させることができ、ピンホール等を発生し難くすることができる。 Further, in the film forming step, for example, the composite particles are deposited in a predetermined shape by electrophoresis, and then the composite particles are deposited on the dried film by the secondary film forming method in which the composite particles are deposited again by electrophoresis. Can also be deposited in multiple batches. Thereby, a conductive composite film having a dense structure can be formed, and pinholes and the like can be hardly generated.
このようにして、複合粒子を所定形状に堆積させた後は、加熱することにより、複合粒子の樹脂の一部を溶融させて複合粒子同士を接着させる。加熱処理は、樹脂の融点以上であって樹脂の熱分解温度より低い温度で、１時間程度行えばよい。 Thus, after depositing the composite particles in a predetermined shape, a part of the resin of the composite particles is melted by heating to bond the composite particles. The heat treatment may be performed for about 1 hour at a temperature equal to or higher than the melting point of the resin and lower than the thermal decomposition temperature of the resin.
以下、実施例について説明する。
（実施例１〜１３、比較例）
導電性粒子として、粒子径が３０〜５０ｎｍ(平均粒子径４０ｎｍ)の中空シェル状のカーボンブラックであるケッチェンブラック（ＫＢ）粉（ＥＣ３００Ｊ粉末品、ケッチェンブラック・インターナショナル製）を用い、樹脂として、ポリフッ化ビニリデン（ＰＶＤＦ）樹脂(呉羽化学工業製)を用いて、本発明に係る複合膜を作製した。
Examples will be described below.
(Examples 1 to 13, comparative example)
As conductive particles, ketjen black (KB) powder (EC300J powder, manufactured by ketjen black international), which is hollow shell-shaped carbon black with a particle size of 30 to 50 nm (average particle size 40 nm), is used as a resin. A composite membrane according to the present invention was prepared using polyvinylidene fluoride (PVDF) resin (Kureha Chemical Industries).
まず、粉末状のＰＶＤＦ樹脂を、溶剤であるＮ−メチル−２−ピロリドン（ＮＭＰ）（関東化学製）に樹脂の濃度が３〜６ｗｔ％の範囲になるように溶解させ、浅黄色透明のＰＶＤＦ樹脂の溶液を調製した。この溶液にＫＢ粉を適量（具体的には、後述の表４に示す固形分比率になる量)添加して撹拌し、黒い糊状の混合液を得た。この後、ＫＢ粉が均一に分散するように、混合液を３０分間超音波分散させ、さらに、乳化分散装置（ｃｌｅａｒｍｉｘ、エム・テクニック製）を用いて、６０００ｒｐｍの回転速度で２０分間分散させた。そして、このようにして得られた混合液を、貧溶媒である多量の高純度エタノールに注入し、乳化分散装置を用いて、７５００ｒｐｍの回転速度で２５分間分散させ、樹脂粒子の粒子径が０．５〜１．５μｍの複合粒子が析出して高均一度に分散する安定な懸濁液を作製した。懸濁液の配合は、ＫＢ：０．２〜１ｗｔ％，ＰＶＤＦ：０．５〜２．６ｗｔ％，ＮＭＰ：１８〜２５ｗｔ％，ＥｔＯＨ：７３〜８０ｗｔ％とした。また、固形分の比率は、体積割合で、ＫＢ／ＰＶＤＦ＝（２０〜６０）／（８０〜４０）（ｖ／ｖ）の範囲になるように調製した。なお、ＫＢの密度は２．０ｇ／ｃｍ３、ＰＶＤＦの密度が１．７６ｇ／ｃｍ３である。 First, a powdery PVDF resin is dissolved in N-methyl-2-pyrrolidone (NMP) (manufactured by Kanto Chemical Co., Ltd.) as a solvent so that the resin concentration is in the range of 3 to 6 wt%. A resin solution was prepared. An appropriate amount of KB powder (specifically, an amount that gives a solid content ratio shown in Table 4 described later) was added to this solution and stirred to obtain a black paste-like mixed solution. Thereafter, the mixture was ultrasonically dispersed for 30 minutes so that the KB powder was uniformly dispersed, and further dispersed for 20 minutes at a rotational speed of 6000 rpm using an emulsifying dispersion device (clearmix, manufactured by M Technique). . The mixed liquid thus obtained is poured into a large amount of high-purity ethanol, which is a poor solvent, and dispersed at a rotational speed of 7500 rpm for 25 minutes using an emulsifying dispersion device, so that the particle size of the resin particles is 0. A stable suspension was prepared in which composite particles of 0.5 to 1.5 μm were deposited and dispersed with high uniformity. The composition of the suspension was KB: 0.2-1 wt%, PVDF: 0.5-2.6 wt%, NMP: 18-25 wt%, EtOH: 73-80 wt%. Moreover, the ratio of solid content is a volume ratio, and it prepared so that it might become the range of KB / PVDF = (20-60) / (80-40) (v / v). The density of the KB is the density of 2.0 g / cm 3, PVDF is 1.76 g / cm 3.
得られた懸濁液に、表面の不動態皮膜を除去したステンレス鋼の基板（ＳＵＳ３１６Ｌ，φ２０）、またはこの基板にさらにＮｉ，Ｎｉ−Ａｇ等の金属のめっき処理を施したものを電極として、電極間距離が１．５ｃｍとなるように配置し、１〜３０ｍＡの電流を流して電気泳動を施し、複合粒子をそれぞれカソード側とアノード側に堆積させた。印加電圧は懸濁液の組成によって、数十Ｖ〜数百Ｖの間で変化した。 To the obtained suspension, a stainless steel substrate (SUS316L, φ20) from which the passive film on the surface was removed, or a material obtained by further plating a metal such as Ni, Ni-Ag on the substrate, was used as an electrode. The electrodes were arranged so that the distance between the electrodes was 1.5 cm, and a current of 1 to 30 mA was applied to perform electrophoresis to deposit composite particles on the cathode side and the anode side, respectively. The applied voltage varied between several tens of volts to several hundred volts depending on the composition of the suspension.
この後、複合粒子をカソード側、アノード側に堆積させたものを、基板である電極ごと取り出して、室温で２時間乾燥させた後、１時間熱処理し、複合膜を作製した。このようにして得られたそれぞれの複合膜について、その表面を電子顕微鏡で観察すると、カソード側に形成した複合膜には、図１に示すように、多数のピンホールが確認された。これは、ＫＢの表面に含まれた水素イオンがカソード側において水素ガスとなるためであると考えられる。一方、アノード側に形成した複合膜は、図２に示すように、ピンホール等のない均質な膜となっていることが確認され、また図３に示すように、複合粒子の樹脂同士が溶融接着した部分にＫＢが高密度な状態で分散していることが確認できた。したがって、複合粒子はアノード側に堆積させる方がより好ましいことが分かった。 Thereafter, the composite particles deposited on the cathode side and the anode side were taken out together with the electrode as the substrate, dried at room temperature for 2 hours, and then heat treated for 1 hour to produce a composite film. When the surface of each composite film thus obtained was observed with an electron microscope, a large number of pinholes were confirmed in the composite film formed on the cathode side as shown in FIG. This is presumably because hydrogen ions contained on the surface of KB become hydrogen gas on the cathode side. On the other hand, the composite film formed on the anode side was confirmed to be a homogeneous film without pinholes as shown in FIG. 2, and the composite particle resin was melted as shown in FIG. It was confirmed that KB was dispersed at a high density in the bonded part. Therefore, it was found that the composite particles are more preferably deposited on the anode side.
そして、アノード側に形成した複合膜（実施例１〜１３）、及びＫＢを含まないＰＶＤＦの膜（比較例）について、面圧１ＭＰａ、電流１Ａ／ｃｍ２で、それぞれの接触抵抗を調べたところ、表４に示すように、いずれの実施例の導電性複合膜も、比較例の膜に比べて、高い導電性を有することが確認できた。
また、２００℃で処理した複合膜は、１８５℃で処理した複合膜よりも接触抵抗が低下することが分かった。これは、高温で処理する方が、ＫＢのネットワークを維持しつつ、ピンホールなどの欠陥を低減した緻密な複合膜が形成されたためと考えられる。
さらに、基板にめっき処理を施すことによって、接触抵抗が低下することが分かり、ステンレス鋼基板の表面に不動態皮膜が形成されるのを抑制していることが確認できた。なお、Ｎｉめっき処理を施した基板としては、表面に約３μｍのＮｉ層を形成させたものを使用し、Ｎｉ−Ａｇめっき処理を施した基板としては、表面に約１μｍのＮｉ層を形成させた後、そのＮｉ層の上に約５μｍのＡｇ層を形成させたものを使用した。
The contact resistance of the composite film (Examples 1 to 13) formed on the anode side and the PVDF film not containing KB (Comparative Example) was examined at a surface pressure of 1 MPa and a current of 1 A / cm 2. As shown in Table 4, it was confirmed that the conductive composite film of any of the examples had higher conductivity than the film of the comparative example.
Further, it was found that the contact resistance of the composite film treated at 200 ° C. was lower than that of the composite film treated at 185 ° C. This is presumably because a dense composite film in which defects such as pinholes were reduced while the KB network was maintained while processing at a high temperature was performed.
Furthermore, it was found that the contact resistance was lowered by plating the substrate, and it was confirmed that the formation of a passive film on the surface of the stainless steel substrate was suppressed. In addition, as the substrate subjected to the Ni plating treatment, a substrate having a Ni layer of about 3 μm formed on the surface is used, and as the substrate subjected to the Ni-Ag plating treatment, a Ni layer of about 1 μm is formed on the surface. After that, an about 5 μm Ag layer was formed on the Ni layer.
基板に対する密着性については、ＫＢの比率が高くなると低下する傾向があり、ＫＢの比率は、体積割合で２２〜３７％が好ましく、２２〜３３％がより好ましいことが分かった。 The adhesion to the substrate tends to decrease as the KB ratio increases, and the KB ratio is preferably 22 to 37% and more preferably 22 to 33% by volume.
また、実施例２の導電性複合膜を８０℃の酸性雰囲気（ｐＨ＝０）下において放置したところ、２１６時間経過しても、基材からの剥離はなく、酸に対して優れた耐食性を有することが分かった。 In addition, when the conductive composite film of Example 2 was left in an acidic atmosphere (pH = 0) at 80 ° C., it did not peel from the base material even after 216 hours, and had excellent corrosion resistance against acid. It turns out to have.
次に、前記実施例２と同様の基板（不動態皮膜を除去し、導電性複合膜を形成したステンレス鋼の基板）、及び不動態皮膜が付いたステンレス鋼の基板（ＳＵＳ３１６Ｌ、φ２０）のそれぞれについて硫酸浸漬試験を行い、基板の耐食性を調べた。硫酸浸漬試験は、浴温８０℃、ｐＨ約１〜２の硫酸水溶液（４００ｍｌ）に基板を浸漬した後、５００時間まで定期的に溶液を約１０ｍｌずつサンプリングし、溶液に含まれる金属成分を高周波誘導結合プラズマ発光分析装置（ＩＣＰ）で定量した。 Next, a substrate similar to Example 2 (a stainless steel substrate from which the passive film was removed and a conductive composite film was formed) and a stainless steel substrate (SUS316L, φ20) provided with a passive film were respectively provided. Was subjected to a sulfuric acid immersion test to examine the corrosion resistance of the substrate. In the sulfuric acid immersion test, the substrate is immersed in a sulfuric acid aqueous solution (400 ml) having a bath temperature of 80 ° C. and a pH of about 1 to 2, and the solution is periodically sampled about 10 ml at a time up to 500 hours. Quantification was performed with an inductively coupled plasma optical emission spectrometer (ICP).
その結果、表５、及び図４、５に示すように、導電性複合膜を形成した基板は、不動態皮膜が付いた基板に比べて優れた耐食性を有することが分かった。従来、表面に不動態皮膜が付いたステンレス鋼の基板は、接触抵抗が大きいものの、不動態皮膜により高い耐食性が維持されることが知られている。しかし、本発明に係る導電性複合膜を形成した基板の場合では、不動態皮膜が付いた基板の場合に比べて、５００時間後のＦｅ，Ｃｒ，Ｎｉの溶出量がそれぞれ約１／３，１／４，１／６に低減しており、複合膜によって、さらに高い耐食性が維持されていることが分かった。
したがって、本発明に係る導電性複合膜は、ピンホール等がない緻密な膜にすることにより、ＰＥＦＣの動作環境等のｐＨ２程度の酸性雰囲気に対して、優れた耐食性を有することが確認できた。
As a result, as shown in Table 5 and FIGS. 4 and 5, it was found that the substrate on which the conductive composite film was formed had excellent corrosion resistance as compared with the substrate with the passive film. Conventionally, it is known that a stainless steel substrate having a passive film on its surface has high contact resistance but maintains high corrosion resistance due to the passive film. However, in the case of the substrate on which the conductive composite film according to the present invention is formed, the elution amount of Fe, Cr, Ni after 500 hours is about 1/3, respectively, as compared with the case of the substrate with the passive film. It has been reduced to 1/4 and 1/6, and it was found that even higher corrosion resistance is maintained by the composite film.
Therefore, it was confirmed that the conductive composite film according to the present invention has excellent corrosion resistance against an acidic atmosphere having a pH of about 2, such as the operating environment of PEFC, by forming a dense film having no pinholes or the like. .
本発明に係る導電性複合膜は、高い導電性を有するため、燃料電池用セパレータや、シールド材、帯電防止材等に適用でき、特に耐食性を有する場合には、固体高分子型燃料電池のセパレータ等の燃料電池用途、及び他の各種耐酸性が要求される導電膜用途等に適用することができる。 Since the conductive composite membrane according to the present invention has high conductivity, it can be applied to a separator for a fuel cell, a shield material, an antistatic material or the like, and particularly when it has corrosion resistance, a separator for a solid polymer fuel cell The present invention can be applied to fuel cell applications such as those described above and other conductive film applications that require various acid resistances.
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| JP2009230951A (en) * | 2008-03-21 | 2009-10-08 | Nec Corp | Polymer radical material-conductive material complex, method of manufacturing the same, and energy storage device |
| KR20160033857A (en) * | 2014-09-18 | 2016-03-29 | (주)엘지하우시스 | Flow channel plate for fuel cell and method of manufacturing the same |
| JP2017071218A (en) * | 2015-10-05 | 2017-04-13 | 新日鉄住金マテリアルズ株式会社 | Stainless steel sheet-carbon composite material and method for producing the same |
| JP2017071219A (en) * | 2015-10-05 | 2017-04-13 | 新日鉄住金マテリアルズ株式会社 | Stainless steel sheet-carbon composite material and method for producing the same |
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| JP2001085030A (en) * | 1999-09-13 | 2001-03-30 | Hitachi Chem Co Ltd | Manufacture of separator for fuel cell, separator for fuel cell obtained in this manufacture and fuel cell using separator for fuel cell |
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| JP2005251747A (en) * | 2004-02-27 | 2005-09-15 | General Motors Corp <Gm> | Bilayer coating system for electrically conductive element in fuel cell |
| JP2006294407A (en) * | 2005-04-11 | 2006-10-26 | Shin Etsu Polymer Co Ltd | Manufacturing method of separator for fuel cell and separator for fuel cell |
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| JPH11297337A (en) * | 1998-04-08 | 1999-10-29 | Tokai Carbon Co Ltd | Separator member for solid polymer type fuel cell, and manufacture thereof |
| JP2001085030A (en) * | 1999-09-13 | 2001-03-30 | Hitachi Chem Co Ltd | Manufacture of separator for fuel cell, separator for fuel cell obtained in this manufacture and fuel cell using separator for fuel cell |
| JP2004119398A (en) * | 2001-01-16 | 2004-04-15 | Showa Denko Kk | Catalyst composition for battery, gas diffusion layer, and fuel cell equipped with them |
| JP2005251747A (en) * | 2004-02-27 | 2005-09-15 | General Motors Corp <Gm> | Bilayer coating system for electrically conductive element in fuel cell |
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| JP2009230951A (en) * | 2008-03-21 | 2009-10-08 | Nec Corp | Polymer radical material-conductive material complex, method of manufacturing the same, and energy storage device |
| KR20160033857A (en) * | 2014-09-18 | 2016-03-29 | (주)엘지하우시스 | Flow channel plate for fuel cell and method of manufacturing the same |
| KR102003682B1 (en) * | 2014-09-18 | 2019-07-26 | (주)엘지하우시스 | Flow channel plate for fuel cell and method of manufacturing the same |
| JP2017071218A (en) * | 2015-10-05 | 2017-04-13 | 新日鉄住金マテリアルズ株式会社 | Stainless steel sheet-carbon composite material and method for producing the same |
| JP2017071219A (en) * | 2015-10-05 | 2017-04-13 | 新日鉄住金マテリアルズ株式会社 | Stainless steel sheet-carbon composite material and method for producing the same |
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