JP5828623B2 - Gas diffusion layer for polymer electrolyte fuel cell having conductive porous layer formed thereon and polymer electrolyte fuel cell using the same - Google Patents

Gas diffusion layer for polymer electrolyte fuel cell having conductive porous layer formed thereon and polymer electrolyte fuel cell using the same Download PDF

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JP5828623B2
JP5828623B2 JP2010196106A JP2010196106A JP5828623B2 JP 5828623 B2 JP5828623 B2 JP 5828623B2 JP 2010196106 A JP2010196106 A JP 2010196106A JP 2010196106 A JP2010196106 A JP 2010196106A JP 5828623 B2 JP5828623 B2 JP 5828623B2
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conductive porous
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polymer electrolyte
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JP2012054111A (en
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直也 竹内
直也 竹内
弘光　礼
礼 弘光
浦田　信也
信也 浦田
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Dai Nippon Printing Co Ltd
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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
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    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
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    • Y02E60/50—Fuel cells

Description

本発明は、導電性多孔質層が形成された固体高分子形燃料電池用ガス拡散層及びそれを用いた固体高分子形燃料電池に関する。   The present invention relates to a gas diffusion layer for a polymer electrolyte fuel cell in which a conductive porous layer is formed, and a polymer electrolyte fuel cell using the same.

固体高分子形燃料電池を構成する電解質膜−電極接合体（ＭＥＡ）は、ガス拡散層、触媒層、イオン伝導性固体高分子電解質膜、触媒層及びガス拡散層が順次積層された構造を有している。   The electrolyte membrane-electrode assembly (MEA) constituting the polymer electrolyte fuel cell has a structure in which a gas diffusion layer, a catalyst layer, an ion conductive solid polymer electrolyte membrane, a catalyst layer, and a gas diffusion layer are sequentially laminated. doing.

このうち、ガス拡散層は、セパレータから供給されるガスを触媒層に均一に行き渡らせる役割を果たすため、良好なガス透過性及び拡散性を備えていることが必要とされる。また、触媒層で発生した電子が効率的にセパレータへ輸送されるための導電性を有していることも必要である。このため、ガス拡散層の材質には、カーボンペーパー等の導電性多孔質基材が一般的に使用されている。   Among these, since the gas diffusion layer plays a role of uniformly distributing the gas supplied from the separator to the catalyst layer, it is required to have good gas permeability and diffusibility. In addition, it is necessary that the electrons generated in the catalyst layer have conductivity to be efficiently transported to the separator. For this reason, a conductive porous substrate such as carbon paper is generally used as the material of the gas diffusion layer.

更に、この導電性多孔質基材上に導電性炭素粒子や撥水性樹脂などからなる導電性多孔質層を形成することでガス拡散層のガス透過性・ガス拡散性の制御や抵抗値を低減することができる。   Furthermore, by forming a conductive porous layer made of conductive carbon particles, water-repellent resin, etc. on this conductive porous substrate, control of gas permeability and gas diffusibility of the gas diffusion layer and resistance value are reduced. can do.

従来の導電性多孔質層の作製方法としては、まず特許文献１の請求項２の様に、撥水性樹脂の低分子量と高分子量の２成分のフッ素系樹脂を混合して使用する場合がある。しかし、高分子量のフッ素系樹脂が繊維化を引起すため、ペースト内で塊状の物質を形成するため成膜に悪影響を与えるため、導電性多孔質層の形成が困難である。仮にガス拡散層を作製できたとしても、この状態のペーストを使用した場合、導電性多孔質層の薄膜形成が困難となり、ガス透過性へ悪影響を及ぼす。   As a conventional method for producing a conductive porous layer, first, as in claim 2 of Patent Document 1, there are cases where a low molecular weight and high molecular weight two-component fluorine-based resin of a water-repellent resin is mixed and used. . However, since the high molecular weight fluorine-based resin causes fibrosis, a bulky substance is formed in the paste, and thus the film formation is adversely affected. Therefore, it is difficult to form a conductive porous layer. Even if a gas diffusion layer can be produced, if a paste in this state is used, it becomes difficult to form a thin film of the conductive porous layer, which adversely affects gas permeability.

また、撥水性樹脂として繊維化された撥水材を使用することも知られているが、特許文献１の場合と同様にペースト作製段階で塊状の物質が多量に形成され、成膜性へ悪影響を及ぼす。また、ペースト粘度増加により薄膜形成が困難なことや、繊維化する状況を毎回、同様に制御することは困難であるためペーストの安定性も乏しい。   It is also known to use a water-repellent material made of fiber as a water-repellent resin, but in the same manner as in Patent Document 1, a large amount of agglomerated material is formed at the paste preparation stage, which adversely affects film formability. Effect. In addition, the stability of the paste is poor because it is difficult to form a thin film due to an increase in paste viscosity, and it is difficult to control the fiber formation state each time.

また特許文献２の様に、非繊維状撥水材として低分子量（分子量：１００万以下）のもののみを使用した場合、導電性多孔質層を形成するためのペースト作製時での繊維化を起こさないため、ペースト作製は容易である。しかし、このペーストを用いて導電性多孔質基材上に導電性多孔質層を形成すると、バインダー成分の柔軟性が低く、また基材との密着性が悪く膜剥離を起こし易いために、成膜性の悪い膜しか形成できないため、導電性多孔質層の形成が困難である。   Further, as in Patent Document 2, when only a non-fibrous water repellent material having a low molecular weight (molecular weight: 1 million or less) is used, fiberization at the time of preparing a paste for forming a conductive porous layer is performed. Since it does not occur, the paste is easy to make. However, when a conductive porous layer is formed on a conductive porous substrate using this paste, the flexibility of the binder component is low, and the adhesion to the substrate is poor, and film peeling tends to occur. Since only a film having poor film properties can be formed, it is difficult to form a conductive porous layer.

また導電性多孔質層は触媒層上へ燃料を供給する最近接部位であり、導電性多孔質層のクラックの入り方と細孔形成がガス透過性やガス拡散性に大きく影響を及ぼし、発電性能を左右する。しかし、この導電性多孔質層のクラック形成状態と細孔形成状態を共に良好に満たすものは存在しない。   In addition, the conductive porous layer is the closest part that supplies fuel onto the catalyst layer, and the cracking and pore formation of the conductive porous layer greatly affects the gas permeability and gas diffusivity. It affects the performance. However, there is no material that satisfactorily satisfies both the crack formation state and the pore formation state of this conductive porous layer.

特開２００６−２７８０３７号公報JP 2006-278037 A 特開２００２−２５５７５号公報JP 2002-25575 A

本発明は、上記、導電性多孔質層の形成に関する課題を解決しようとするものであり、安定性のある導電性多孔質層形成用ペーストを作製し、一段と優れたガス透過性及びガス拡散性を付与できる導電性多孔質層が導電性多孔質基材上に形成されたガス拡散層及びそれを用いた固体高分子形燃料電池を提供することを課題とする。   The present invention is intended to solve the above-mentioned problems related to the formation of a conductive porous layer, and to produce a stable conductive porous layer forming paste, and further excellent gas permeability and gas diffusibility. It is an object of the present invention to provide a gas diffusion layer in which a conductive porous layer capable of imparting water is formed on a conductive porous substrate, and a polymer electrolyte fuel cell using the gas diffusion layer.

本発明者らは、上記課題に鑑み、導電性多孔質基材（ガス拡散層）に所望の性能を付与すべく、鋭意研究を重ねてきた。その結果、特定の成分を特定量含む導電性多孔質層形成用ペーストを作製し、その導電性多孔質層を導電性多孔質基材の表面上に形成させることにより、上記課題を解決でき、導電性多孔質基材に一段と優れたガス透過性及びガス拡散性を付与できることを見出した。本発明は、このような知見に基づき完成されたものである。   In view of the above problems, the present inventors have conducted intensive studies to impart desired performance to a conductive porous substrate (gas diffusion layer). As a result, by producing a conductive porous layer forming paste containing a specific amount of a specific component, and forming the conductive porous layer on the surface of the conductive porous substrate, the above problem can be solved, It has been found that further excellent gas permeability and gas diffusibility can be imparted to the conductive porous substrate. The present invention has been completed based on such findings.

すなわち、本発明は、下記のガス拡散層及びそれを用いた固体高分子形燃料電池を包含する。   That is, the present invention includes the following gas diffusion layer and a polymer electrolyte fuel cell using the same.

項１．導電性多孔質基材上に、導電性多孔質層が形成された固体高分子形燃料電池用ガス拡散層であって、前記導電性多孔質層は、少なくとも導電性炭素粒子、及び撥水性樹脂を含み、
前記導電性多孔質層は、細孔径が２５〜１０００ｎｍの細孔容積の和が１．４ｍｌ／ｇ以上であり、且つ、クラック占有面積が０．８％〜２．５％であり、
前記撥水性樹脂の数平均分子量が、１００万より大きく、５００万より小さい、固体高分子形燃料電池用ガス拡散層。 Item 1. A gas diffusion layer for a polymer electrolyte fuel cell in which a conductive porous layer is formed on a conductive porous substrate, wherein the conductive porous layer includes at least conductive carbon particles, and a water-repellent resin. the fat seen including,
The conductive porous layer, the pore diameter is at the sum of the pore volume of 25~1000nm is 1.4 ml / g or more, and crack area occupied Ri 0.8% to 2.5% der,
A gas diffusion layer for a polymer electrolyte fuel cell , wherein the water repellent resin has a number average molecular weight of greater than 1 million and less than 5 million .

項２．前記導電性多孔質層は、さらに、分散剤を含む、項１に記載の固体高分子形燃料電池用ガス拡散層。 Item 2. Item 2. The gas diffusion layer for a polymer electrolyte fuel cell according to Item 1, wherein the conductive porous layer further contains a dispersant .

項３．分散剤がノニオン系分散剤である、項１又は２に記載の固体高分子形燃料電池用ガス拡散層。   Item 3. Item 3. The gas diffusion layer for a polymer electrolyte fuel cell according to Item 1 or 2, wherein the dispersant is a nonionic dispersant.

項４．さらに、導電性炭素繊維を含む、項１〜３のいずれかに記載の固体高分子形燃料電池用ガス拡散層。
項５．前記撥水性樹脂は、繊維化していない、項１〜４のいずれかに記載の固体高分子形燃料電池用ガス拡散層。
項６．前記導電性多孔質基材は、カーボンペーパー、カーボンクロス、又はカーボン不織布である、項１〜５のいずれかに記載の固体高分子形燃料電池用ガス拡散層。 Item 4. Item 4. The gas diffusion layer for a polymer electrolyte fuel cell according to any one of Items 1 to 3, further comprising conductive carbon fibers.
Item 5. The water-repellent resin is not fiber維化, a polymer electrolyte fuel cell gas diffusion layer according to any one of claim 1 to 4.
Item 6. Item 6. The gas diffusion layer for a polymer electrolyte fuel cell according to any one of Items 1 to 5, wherein the conductive porous substrate is carbon paper, carbon cloth, or carbon nonwoven fabric.

項７．項１〜６のいずれかに記載のガス拡散層を用いた固体高分子形燃料電池。 Item 7 . Item 7. A polymer electrolyte fuel cell using the gas diffusion layer according to any one of Items 1 to 6 .

項８．項１〜６のいずれかに記載のガス拡散層の製造に用いられる導電性多孔質層形成用ペースト組成物であって、少なくとも導電性炭素粒子、数平均分子量が１００万より大きく５００万より小さい撥水性樹脂、及び分散剤を含む導電性多孔質層形成用ペースト組成物。 Item 8. Item 7. A conductive porous layer forming paste composition used in the production of a gas diffusion layer according to any one of Items 1 to 6, wherein at least conductive carbon particles have a number average molecular weight of more than 1,000,000 and less than 5,000,000. water-repellent resin, electrically conductive porous layer forming paste composition comprising及beauty dispersing agent.

項９．さらに、導電性炭素繊維を含む、項８に記載の導電性多孔質層形成用ペースト組成物。 Item 9 . Item 9. The conductive porous layer forming paste composition according to Item 8 , further comprising conductive carbon fibers.

項１０．少なくとも導電性炭素粒子、数平均分子量が１００万より大きく５００万より小さい撥水性樹脂、及び分散剤を、０．１〜０．８５ｍ／ｓの周速で攪拌させる工程を備える、項８又は９に記載の導電性多孔質層形成用ペースト組成物の製造方法。 Item 10. Comprising at least conductive carbon particles, the number average molecular weight 1,000,000 greater than 5 million less water-repellent resin, the及beauty dispersing agent, the step of stirring at a peripheral speed of 0.1~0.85m / s, claim 8 or 10. A method for producing a conductive porous layer forming paste composition according to 9.

１．ガス拡散層
本発明のガス拡散層は、ガス透過性及び拡散性が良好な導電性多孔質層が、導電性多孔質基材上に形成される。なお、この導電性多孔質層は、「Ｍｉｃｒｏ−ｐｏｒｏｕｓ Ｌａｙｅｒ」（ＭＰＬ）とも称されている。 1. Gas diffusion layer In the gas diffusion layer of the present invention, a conductive porous layer having good gas permeability and diffusibility is formed on a conductive porous substrate. This conductive porous layer is also referred to as “Micro-porous Layer” (MPL).

＜導電性多孔質層＞
前記導電性多孔質層は、少なくとも導電性炭素粒子、撥水性樹脂及び分散剤を含む導電性多孔質層形成用ペースト組成物により形成されてなる層である。この導電性多孔質層は、前記導電性多孔質層形成用ペースト組成物を塗布し、乾燥及び焼成させることにより、形成することができる。 <Conductive porous layer>
The conductive porous layer is a layer formed by a conductive porous layer forming paste composition containing at least conductive carbon particles, a water repellent resin, and a dispersant. This conductive porous layer can be formed by applying the conductive porous layer forming paste composition, drying and baking.

導電性炭素粒子
導電性炭素粒子は、導電性を有する炭素材であれば特に限定されず、公知又は市販のものを使用できる。例えば、チャンネルブラック、ファーネスブラック、ケッチェンブラック、アセチレンブラック、ランプブラック等のカーボンブラック、黒鉛、活性炭等が挙げられる。これらは、１種単独又は２種以上で用いることができる。導電性炭素粒子等を含有する導電性多孔質層（ＭＰＬ）を施すことによりガス拡散層の導電性を向上させることができる。 Conductive carbon particles The conductive carbon particles are not particularly limited as long as they are conductive carbon materials, and known or commercially available ones can be used. Examples thereof include carbon black such as channel black, furnace black, ketjen black, acetylene black and lamp black, graphite, activated carbon and the like. These can be used alone or in combination of two or more. The conductivity of the gas diffusion layer can be improved by applying a conductive porous layer (MPL) containing conductive carbon particles and the like.

導電性炭素粒子の平均粒子径（算術平均粒子径）は限定的でなく、通常５ｎｍ〜２００ｎｍ程度、好ましくは２０ｎｍ〜８０ｎｍ程度とすればよい。この導電性炭素粒子の平均粒子径は、例えば、粒子径分布測定装置ＬＡ−９２０：（株）堀場製作所製等により測定できる。   The average particle diameter (arithmetic average particle diameter) of the conductive carbon particles is not limited and is usually about 5 nm to 200 nm, preferably about 20 nm to 80 nm. The average particle size of the conductive carbon particles can be measured by, for example, a particle size distribution measuring device LA-920: manufactured by Horiba, Ltd.

撥水性樹脂
撥水性樹脂としては、フッ素系樹脂、シリコーン樹脂等が挙げられ、フッ素系樹脂が好ましい。 Examples of the water- repellent resin include a fluorine-based resin and a silicone resin, and a fluorine-based resin is preferable.

撥水性樹脂としては、数平均分子量が１００万より大きく、５００万より小さいものが好ましく、特に２００万〜４００万程度のものが好ましい。数平均分子量が小さい程バインダーとしての機能が低く、塗膜に多くのクラックが発生し、電池性能も低下し、大きい程、繊維化する撥水性樹脂が増加し、撥水性樹脂とカーボン材料との凝集物を生成し易い。なお、凝集物が多く生じると導電性多孔質層の表面起伏も大きくなり接触抵抗が増加する傾向にある。また成膜後の膜中に凝集物が多く存在すると導電性多孔質層のガス透過性及びガス拡散性に対しても悪影響を及ぼす。なお、撥水性樹脂の数平均分子量は、例えば、融点や標準比重により測定することができる。   As the water repellent resin, those having a number average molecular weight of more than 1 million and less than 5 million are preferable, and those having a molecular weight of about 2 to 4 million are particularly preferable. The smaller the number average molecular weight, the lower the function as a binder, the more cracks occur in the coating film, and the battery performance also decreases.The larger the number average molecular weight, the more water-repellent resin to be fibrillated. It is easy to produce aggregates. In addition, when many aggregates arise, the surface undulation of a conductive porous layer will also become large, and it exists in the tendency for contact resistance to increase. In addition, if a large amount of aggregates are present in the film after film formation, the gas permeability and gas diffusibility of the conductive porous layer are also adversely affected. In addition, the number average molecular weight of water-repellent resin can be measured by melting | fusing point or standard specific gravity, for example.

このような撥水性樹脂を使用することで、撥水性樹脂が繊維化しにくく、成膜性及び安定性が優れるペースト組成物を作製できる。なお、本発明のペースト組成物において、「撥水性樹脂が繊維化しない」とは、導電性多孔質層形成用ペースト組成物を乾燥させた際に、撥水性樹脂からなる１００ｎｍ以下の繊維径の繊維が実質的に存在しない状態を言う。また、撥水性樹脂が繊維化しているかどうかは、例えば、導電性多孔質層形成用ペーストを乾燥させた物の表面又は断面をエネルギー分散型Ｘ線分析装置（ＥＤＸ）、走査型顕微鏡（ＳＥＭ）等により観察することができる。   By using such a water-repellent resin, a paste composition in which the water-repellent resin is less likely to be fiberized and excellent in film formability and stability can be produced. In the paste composition of the present invention, “the water-repellent resin is not fiberized” means that when the conductive porous layer forming paste composition is dried, the fiber diameter is 100 nm or less made of the water-repellent resin. A state in which fibers are not substantially present. Whether or not the water repellent resin is fiberized is determined, for example, by using an energy dispersive X-ray analyzer (EDX) or a scanning microscope (SEM) on the surface or cross section of the dried product of the conductive porous layer forming paste. Etc. can be observed.

好ましい撥水性樹脂としては、例えば、ポリテトラフルオロエチレン樹脂（ＰＴＦＥ）、フッ化エチレンプロピレン樹脂（ＦＥＰ）、パーフルオロアルコキシ樹脂（ＰＦＡ）、テトラフルオロエチレン−エチレン共重合体（ＥＴＦＥ）等が挙げられる。具体的には、例えば、市販のＡＤ９１１Ｌ（旭硝子（株）製）、Ｄ−２１０C（ダイキン工業（株）製）を使用できる。なかでも、ＡＤ９１１Ｌ（旭硝子（株）製）等が好ましい。   Preferable water-repellent resins include, for example, polytetrafluoroethylene resin (PTFE), fluorinated ethylene propylene resin (FEP), perfluoroalkoxy resin (PFA), tetrafluoroethylene-ethylene copolymer (ETFE), and the like. . Specifically, for example, commercially available AD911L (manufactured by Asahi Glass Co., Ltd.) and D-210C (manufactured by Daikin Industries, Ltd.) can be used. Especially, AD911L (Asahi Glass Co., Ltd. product) etc. are preferable.

このような撥水性樹脂を含有することにより、ガス拡散層に撥水性を付与できると共に、導電性炭素粒子を導電性多孔質基材表面により強固に結着できるため、撥水性を長期に亘り保持することができる。なお、撥水性樹脂としては、数平均分子量が１００万より大きく５００万より小さいもののみを使用してもよいが、本発明の効果を損なわない範囲で、数平均分子量が１００万より大きく５００万より小さい樹脂と、数平均分子量が１００万以下の樹脂とを併用してもよい。   By containing such a water-repellent resin, water repellency can be imparted to the gas diffusion layer, and the conductive carbon particles can be more firmly bound to the surface of the conductive porous substrate, thus maintaining the water repellency for a long period of time. can do. As the water repellent resin, only those having a number average molecular weight of more than 1,000,000 and less than 5,000,000 may be used. However, the number average molecular weight of more than 1,000,000 is greater than 5 million within a range not impairing the effects of the present invention. A smaller resin and a resin having a number average molecular weight of 1,000,000 or less may be used in combination.

分散剤
分散剤は、本発明ではカーボン材料との吸着性と撥水性樹脂との濡れ性の観点から、カーボン材料と撥水性樹脂を水中で分散させることができるものを使用すればよい。例えば、ポリオキシエチレンジスチレン化フェニルエーテル、ポリオキシエチレンアルキレンアルキルエーテル、ポリエチレングリコールアルキルエーテル等のノニオン系分散剤、アルキルトリメチルアンモニウム塩、ジアルキルジメチルアンモニウムクロリド、アルキルピリジウムクロリド等のカチオン系分散剤、ポリオキシエチレン脂肪酸エステル、酸性基含有構造変性ポリアクリレート等のアニオン系分散剤等を、カーボン材料及び撥水性樹脂の種類に応じて使用すればよい。例えば、導電性炭素粒子としてファーネスブラック、導電性炭素繊維としてＶＧＣＦ、撥水性樹脂として数平均分子量が１００万〜５００万のＰＴＦＥを使用する場合には、ノニオン系分散剤、特に、アリール基が構造中にあることが好ましい。 In the present invention, a dispersant that can disperse the carbon material and the water-repellent resin in water may be used from the viewpoint of adsorbability with the carbon material and wettability with the water-repellent resin. For example, nonionic dispersants such as polyoxyethylene distyrenated phenyl ether, polyoxyethylene alkylene alkyl ether, polyethylene glycol alkyl ether, cationic dispersants such as alkyltrimethylammonium salt, dialkyldimethylammonium chloride, alkylpyridinium chloride, Anionic dispersants such as polyoxyethylene fatty acid esters and acidic group-containing structurally modified polyacrylates may be used depending on the type of carbon material and water-repellent resin. For example, in the case where furnace black is used as the conductive carbon particles, VGCF is used as the conductive carbon fiber, and PTFE having a number average molecular weight of 1,000,000 to 5,000,000 is used as the water repellent resin, the nonionic dispersant, in particular, the aryl group has a structure. It is preferable to be inside.

導電性炭素繊維
導電性多孔質層形成用ペースト組成物は、上記以外の成分として導電性炭素繊維を含有していてもよい。導電性炭素繊維を配合することにより、ペースト塗布表面でのクラックの発生状態を制御でき、且つ導電性が一段と向上する。導電性炭素繊維としては、例えば気相成長法炭素繊維（ＶＧＣＦ）、カーボンナノチューブ、カーボンナノワイヤー等が挙げられる。これらの導電性炭素繊維は、単独で用いてもよいし、２種以上を組み合わせて用いてもよい。繊維径は限定的でなく、平均が５０〜４００ｎｍ、好ましくは１００〜２５０ｎｍ程度とすればよい。繊維長も限定的でなく、平均が５〜５０μｍ、好ましくは１０〜２０μｍ程度とすればよい。アスペクト比は、およそ１０〜５００である。なお、導電性炭素繊維の繊維径、繊維長及びアスペクト比は、走査型電子顕微鏡（ＳＥＭ）等により測定した画像等により測定できる。 The conductive carbon fiber conductive porous layer forming paste composition may contain conductive carbon fiber as a component other than the above. By blending the conductive carbon fiber, the state of occurrence of cracks on the paste application surface can be controlled, and the conductivity is further improved. Examples of the conductive carbon fiber include vapor grown carbon fiber (VGCF), carbon nanotube, and carbon nanowire. These conductive carbon fibers may be used alone or in combination of two or more. The fiber diameter is not limited, and the average may be 50 to 400 nm, preferably about 100 to 250 nm. The fiber length is not limited, and the average may be 5 to 50 μm, preferably about 10 to 20 μm. The aspect ratio is approximately 10 to 500. The fiber diameter, fiber length, and aspect ratio of the conductive carbon fiber can be measured by an image measured with a scanning electron microscope (SEM) or the like.

アルコール
導電性多孔質層形成用ペースト組成物は、上記以外の成分としてアルコールを含有していてもよい。このようなアルコールとしては、例えば、炭素数１〜５程度の１価又は多価のアルコールが挙げられる。具体的には、メタノール、エタノール、１−プロパノール、イソプロパノール、１−ブタノール、１−ペンタノール等が挙げられる。 The paste composition for forming an alcohol conductive porous layer may contain alcohol as a component other than the above. Examples of such alcohol include monovalent or polyhydric alcohols having about 1 to 5 carbon atoms. Specific examples include methanol, ethanol, 1-propanol, isopropanol, 1-butanol, and 1-pentanol.

含有量及び特性
導電性多孔質層形成用ペースト組成物の配合割合は、例えば、導電性炭素粒子１００重量部に対して、撥水性樹脂５〜４００重量部（好ましくは１０〜３５０重量部）程度、分散剤５〜２００重量部（好ましくは１０〜１５０重量部）、水１０〜２０００重量部（好ましくは１００〜１０００重量部）とすればよい。導電性多孔質層形成用ペースト組成物中に導電性炭素繊維、アルコール等を含ませる場合には、これらの含有量は、導電性炭素粒子１００重量部に対して、導電性炭素繊維は１５〜７０重量部程度（好ましくは２５〜６０重量部程度）、アルコールは５〜１００重量部程度とすればよい。 Content and Characteristics The blending ratio of the conductive porous layer forming paste composition is, for example, about 5 to 400 parts by weight (preferably 10 to 350 parts by weight) of the water-repellent resin with respect to 100 parts by weight of the conductive carbon particles. The dispersant may be 5 to 200 parts by weight (preferably 10 to 150 parts by weight) and water 10 to 2000 parts by weight (preferably 100 to 1000 parts by weight). When conductive carbon fiber, alcohol, or the like is included in the conductive porous layer forming paste composition, the content of conductive carbon fiber is 15 to 100 parts by weight of conductive carbon particles. About 70 parts by weight (preferably about 25 to 60 parts by weight) and alcohol may be about 5 to 100 parts by weight.

本発明では、導電性多孔質層を形成する際には、上記の成分を含有する導電性多孔質層形成用ペースト組成物を使用する。   In this invention, when forming a conductive porous layer, the paste composition for conductive porous layer formation containing said component is used.

導電性多孔質層形成用ペースト組成物は、例えば、上記の導電性炭素粒子、導電性炭素繊維、分散剤、水、アルコール各成分を混合、分散させた後に、撥水性樹脂を加えて攪拌させて得ることができる。分散方法としては、特に制限されず、例えば公知の超音波分散、ホモジナイザー、メディア分散、スターラー分散等を用いればよい。また攪拌方法としては、特に制限されず、例えば公知の攪拌機を用いれば良い。   The conductive porous layer forming paste composition is prepared by, for example, mixing and dispersing the conductive carbon particles, conductive carbon fiber, dispersant, water, and alcohol components, and then adding a water-repellent resin and stirring the mixture. Can be obtained. The dispersion method is not particularly limited, and for example, known ultrasonic dispersion, homogenizer, media dispersion, stirrer dispersion, or the like may be used. The stirring method is not particularly limited, and for example, a known stirrer may be used.

攪拌条件も特に制限されるわけではないが、撥水性樹脂が繊維化しにくい程度の周速、具体的には０．１〜０．８５ｍ／ｓ程度の周速で攪拌することが好ましい。   The stirring conditions are not particularly limited, but it is preferable to stir at a peripheral speed at which the water-repellent resin is less likely to be fiberized, specifically at a peripheral speed of about 0.1 to 0.85 m / s.

本発明の導電性多孔質層は、細孔径が２５〜１０００ｎｍの細孔容積の和が１．４ｍｌ／ｇ以上、好ましくは１．４〜２．５ｍｌ／ｇ、より好ましくは１．４〜２．０ｍｌ／ｇである。この細孔容積の和は、例えば、自動ポロシメーター オートポアＩＶ９５００（（株）島津製作所製）により測定できる。測定は、例えば、１ｃｍ×１ｃｍ〜５ｃｍ×５ｃｍの大きさにガス拡散層を切り分けて測定冶具に充填し、０〜６５０００［ｐｓｉａ］の低圧〜高圧まで圧力がかけられる際にサンプル内へ入り込む水銀充填量が１０〜８０％となる様に調節し、各圧力値での水銀圧入量から、細孔径と細孔容積とを算出することができる。また、例えば、市販の導電性多孔質基材（東レ（株）製のＴＧＰ−Ｈ−０６０）のみを測定した場合、１０〜１００μｍの範囲で細孔径分布が存在するのに対して、導電性多孔質層を塗工した導電性多孔質基材を測定した場合１０〜１００μｍの範囲の細孔径分布に加えて２５〜１０００ｎｍの範囲の細孔径分布も観察できる。このことから、導電性多孔質層に由来する細孔径分布を２５〜１０００ｎｍと判断し、細孔径分布における２５〜１０００ｎｍの細孔容積の総和を算出することで導電性多孔質層全体の気孔状態へと換算することができる。本発明者らは、細孔径分布における２５〜１０００ｎｍの細孔容積の和を算出した結果、導電性多孔質基材上に塗工した導電性多孔質層のみの重量と細孔容積の比が１．４ｍｌ／ｇ以上の細孔容積を有する導電性多孔質層を形成したガス拡散層が発電性能に対して有効であることを見出した。   In the conductive porous layer of the present invention, the sum of the pore volumes having a pore diameter of 25 to 1000 nm is 1.4 ml / g or more, preferably 1.4 to 2.5 ml / g, more preferably 1.4 to 2. 0.0 ml / g. The sum of the pore volumes can be measured by, for example, an automatic porosimeter Autopore IV9500 (manufactured by Shimadzu Corporation). For the measurement, for example, a gas diffusion layer is cut into a size of 1 cm × 1 cm to 5 cm × 5 cm and filled in a measurement jig, and mercury enters the sample when pressure is applied from low pressure to high pressure of 0 to 65000 [psia]. By adjusting the filling amount to be 10 to 80%, the pore diameter and the pore volume can be calculated from the mercury intrusion amount at each pressure value. For example, when only a commercially available conductive porous substrate (TGP-H-060 manufactured by Toray Industries, Inc.) is measured, the pore size distribution exists in the range of 10 to 100 μm, whereas the conductivity is When a conductive porous substrate coated with a porous layer is measured, a pore size distribution in the range of 25 to 1000 nm can be observed in addition to a pore size distribution in the range of 10 to 100 μm. From this, the pore size distribution derived from the conductive porous layer is determined to be 25 to 1000 nm, and the pore state of the entire conductive porous layer is calculated by calculating the total pore volume of 25 to 1000 nm in the pore size distribution. Can be converted to As a result of calculating the sum of pore volumes of 25 to 1000 nm in the pore diameter distribution, the present inventors have found that the ratio of the weight of only the conductive porous layer coated on the conductive porous substrate to the pore volume is It has been found that a gas diffusion layer formed with a conductive porous layer having a pore volume of 1.4 ml / g or more is effective for power generation performance.

導電性多孔質層は、クラック占有面積が０．８％〜２．５％、好ましくは０．８５％〜２．２５％、より好ましくは０．８８％〜２．０％である。このクラック占有面積は、例えば、ＩＭＡＧＥ−ＰＲＯ ＰＬＵＳ（プラネトロン社製）により測定できる。クラック占有面積の測定は、例えば、導電性多孔質層の表面画像を測定し、画像処理によりクラック部を黒色に、非クラック部を白色となる様に処理を施し、黒色部分の表面画像全体に占める割合を測定することにより行うことが出来る。   The conductive porous layer has a crack occupation area of 0.8% to 2.5%, preferably 0.85% to 2.25%, and more preferably 0.88% to 2.0%. This crack occupation area can be measured by, for example, IMAGE-PRO PLUS (manufactured by Planetron). For example, the area occupied by the crack is measured by measuring the surface image of the conductive porous layer and processing the image so that the cracked portion becomes black and the non-cracked portion becomes white. This can be done by measuring the proportion occupied.

＜導電性多孔質基材＞
導電性多孔質基材としては、燃料電池（特に、固体高分子形燃料電池）で一般的に使用されているものを用いればよく、公知又は市販のものを用いることができる。例えば、カーボンペーパー、カーボンクロス、カーボン不織布（カーボンフェルト）等が挙げられる。 <Conductive porous substrate>
As the conductive porous substrate, those generally used in fuel cells (in particular, polymer electrolyte fuel cells) may be used, and known or commercially available materials can be used. For example, carbon paper, carbon cloth, carbon non-woven fabric (carbon felt) and the like can be mentioned.

またカーボンペーパーの特性について、東レ（株）製のＴＧＰ−Ｈ−０６０を例にとり言及すると、厚み：１９０μｍ、電気抵抗：厚み方向８０ｍΩ・ｃｍ、面方向５．８ｍΩ・ｃｍ、気孔率：７８％、嵩密度：０．４４ｇ／ｃｍ３、表面粗さ：８μｍ等である。 Further, regarding the characteristics of carbon paper, taking TGP-H-060 manufactured by Toray Industries, Inc. as an example, thickness: 190 μm, electric resistance: thickness direction 80 mΩ · cm, surface direction 5.8 mΩ · cm, porosity: 78% , Bulk density: 0.44 g / cm 3 , surface roughness: 8 μm, and the like.

導電性多孔質基材の厚みは限定的ではないが、通常５０μｍ〜１０００μｍ程度、好ましくは１００μｍ〜４００μｍ程度とすればよい。   The thickness of the conductive porous substrate is not limited, but is usually about 50 μm to 1000 μm, preferably about 100 μm to 400 μm.

本発明で使用する導電性多孔質基材は、予め撥水処理が施されたものであることが好ましい。これにより、さらに一段とガス拡散層の撥水性を向上させることができる。また、前記導電性多孔質層を導電性多孔質基材の表面上に設ける際に、より確実に当該基材表面上に形成させることができる。   It is preferable that the conductive porous substrate used in the present invention has been subjected to a water repellent treatment in advance. Thereby, the water repellency of the gas diffusion layer can be further improved. Moreover, when providing the said electroconductive porous layer on the surface of an electroconductive porous base material, it can form on the said base material surface more reliably.

撥水処理としては、例えば、導電性多孔質基材をフッ素系樹脂等が分散した水分散体中に浸漬する方法等が挙げられる。フッ素系樹脂としては、上述したもの等が挙げられる。なお、この際には、水中にフッ素系樹脂を分散させるために、上述した分散剤を用い、フッ素系樹脂及び水系分散剤を含む水系懸濁液として使用することが好ましい。   Examples of the water repellent treatment include a method of immersing a conductive porous substrate in an aqueous dispersion in which a fluorine resin or the like is dispersed. Examples of the fluorine-based resin include those described above. In this case, in order to disperse the fluororesin in water, the above-described dispersant is preferably used as an aqueous suspension containing the fluororesin and the aqueous dispersant.

水分散体中のフッ素系樹脂の含有量は限定的でないが、例えば、水１００重量部に対して、１〜３０重量部程度、好ましくは２〜２０重量部程度とすればよい。   The content of the fluororesin in the aqueous dispersion is not limited, but may be, for example, about 1 to 30 parts by weight, preferably about 2 to 20 parts by weight with respect to 100 parts by weight of water.

＜ガス拡散層の特徴＞
本発明のガス拡散層は、固体高分子形燃料電池用のガス拡散層として使用することができる。具体的には、公知又は市販のイオン伝導性固体高分子電解質膜の両面に触媒層（カソード触媒層及びアノード触媒層）が積層された触媒層−電解質膜積層体（カソード触媒層／電解質膜／アノード触媒層）を用意し、次いで、この両面（カソード触媒層及びアノード触媒層）の少なくとも一つの面（特に、カソード触媒層）に、導電性多孔質層が当該触媒層に接触するように、本発明のガス拡散層を積層させることにより、膜−電極接合体（ガス拡散層／カソード触媒層／電解質膜／アノード触媒層／ガス拡散層）を作製して、これを使用すればよい。 <Characteristics of gas diffusion layer>
The gas diffusion layer of the present invention can be used as a gas diffusion layer for a polymer electrolyte fuel cell. Specifically, a catalyst layer-electrolyte membrane laminate (cathode catalyst layer / electrolyte membrane / in which a catalyst layer (cathode catalyst layer and anode catalyst layer) is laminated on both sides of a known or commercially available ion conductive solid polymer electrolyte membrane) An anode catalyst layer), and then, on at least one surface (particularly the cathode catalyst layer) of both surfaces (the cathode catalyst layer and the anode catalyst layer), the conductive porous layer is in contact with the catalyst layer. By laminating the gas diffusion layer of the present invention, a membrane-electrode assembly (gas diffusion layer / cathode catalyst layer / electrolyte membrane / anode catalyst layer / gas diffusion layer) may be prepared and used.

本発明のガス拡散層は、良好な導電性及び撥水性を兼備する導電性多孔質層が設けられているため、膜−電極接合体（ＭＥＡ）全体の導電性を向上させることができ、またＭＥＡの触媒層で発生する水をより効率的にガス拡散層外部（ひいては、ＭＥＡ外部）に排出できる。このため、本発明のガス拡散層を用いた燃料電池は、優れた電池性能を発揮することができる。   Since the gas diffusion layer of the present invention is provided with a conductive porous layer having both good conductivity and water repellency, the conductivity of the entire membrane-electrode assembly (MEA) can be improved. Water generated in the MEA catalyst layer can be discharged more efficiently to the outside of the gas diffusion layer (and thus to the outside of the MEA). For this reason, the fuel cell using the gas diffusion layer of the present invention can exhibit excellent cell performance.

なお、本発明の固体高分子形燃料電池は、上記の膜−電極接合体に公知又は市販のセパレータを設けることにより得ることができる。   The polymer electrolyte fuel cell of the present invention can be obtained by providing a known or commercially available separator to the membrane-electrode assembly.

２．ガス拡散層の製造方法
本発明のガス拡散層は、燃料電池用導電性多孔質基材の表面上に導電性多孔質層が形成されているものであって、導電性多孔質層形成用ペースト組成物を、導電性多孔質基材表面に塗工し、次いで乾燥及び焼成を行う工程を経ることにより得られる。 2. Manufacturing method of gas diffusion layer The gas diffusion layer of the present invention is a conductive porous layer-forming paste in which a conductive porous layer is formed on the surface of a conductive porous substrate for fuel cells. The composition is obtained by applying the composition to the surface of the conductive porous substrate, followed by drying and firing.

導電性多孔質層形成用ペースト組成物は、導電性多孔質基材との接触角が９０〜１５０°程度（好ましくは１００〜１４０°程度）であることが好ましい。これにより、導電性多孔質層形成用ペースト組成物を導電性多孔質基材に塗布する際に、ペースト組成物が導電性多孔質基材表面ではじく現象を防止でき、ペースト組成物をより均一に塗布できる。   The conductive porous layer forming paste composition preferably has a contact angle with the conductive porous substrate of about 90 to 150 ° (preferably about 100 to 140 °). As a result, when applying the conductive porous layer forming paste composition to the conductive porous substrate, the paste composition can be prevented from repelling on the surface of the conductive porous substrate, and the paste composition can be made more uniform. Can be applied.

前記ペースト組成物と導電性多孔質基材との接触角は、自動接触角測定器（協和界面科学製、「ＦＡＣＥ ＣＡ−Ｘ」等）を用い、１マイクロリットル程度のペースト組成物の液滴を導電性多孔質基材表面に滴下し、３０秒後の接触角を観測することにより求められる。   The contact angle between the paste composition and the conductive porous substrate is about 1 microliter of a paste composition droplet using an automatic contact angle measuring device (Kyowa Interface Science, “FACE CA-X”, etc.). Is dropped on the surface of the conductive porous substrate, and the contact angle after 30 seconds is observed.

本発明では、導電性多孔質層形成用ペースト組成物が導電性多孔質基材内部に実質的に浸透しないように塗布することが好ましい。これにより、導電性多孔質層形成用ペースト組成物が導電性多孔質基材内部に浸透することにより当該基材内部の空隙が閉塞される現象を抑制して、当該基材表面のみに所望の導電性多孔質層を好適に形成させることができる。   In this invention, it is preferable to apply | coat so that the paste composition for conductive porous layer formation may not permeate | transmit substantially inside a conductive porous base material. This suppresses the phenomenon that the conductive porous layer forming paste composition penetrates into the inside of the conductive porous base material to block the voids inside the base material, so that only the surface of the base material is desired. A conductive porous layer can be suitably formed.

このような塗布方法に用いる装置としては、例えば公知又は市販のワイヤーバー、スプレーコート、アプリケーター、ダイコーター等を用いればよい。   As an apparatus used for such a coating method, for example, a known or commercially available wire bar, spray coat, applicator, die coater or the like may be used.

導電性多孔質層形成用ペースト組成物の塗布量は限定的でないが、固形分換算で、例えば、１〜１００ｇ／ｍ２程度、好ましくは５〜５０ｇ／ｍ２程度とすればよい。また、導電性多孔質層形成用ペースト組成物の塗工厚も限定的ではないが、例えば、１〜１００μｍ程度、好ましくは５〜５０μｍ程度とすればよい。 The coating amount of the conductive porous layer forming paste composition is not limited, in terms of solid content, for example, 1 to 100 g / m 2, preferably about may be set to 5 to 50 g / m 2 approximately. Further, the coating thickness of the conductive porous layer forming paste composition is not limited, but may be, for example, about 1 to 100 μm, preferably about 5 to 50 μm.

また、乾燥温度は限定的ではなく、例えば、大気中にて５０〜１５０℃程度、好ましくは９０〜１３０℃程度とすればよい。   Further, the drying temperature is not limited and may be, for example, about 50 to 150 ° C., preferably about 90 to 130 ° C. in the atmosphere.

乾燥時間は、乾燥温度等に応じて適宜決定すればよいが、通常５〜５０分程度、好ましくは１０〜３０分程度である。乾燥後に行う焼成時の温度も限定的ではなく、例えば、大気中にて２００〜４００℃、好ましくは２５０〜３５０℃程度とすればよい。   The drying time may be appropriately determined according to the drying temperature or the like, but is usually about 5 to 50 minutes, preferably about 10 to 30 minutes. The temperature at the time of baking performed after drying is not limited, for example, 200 to 400 ° C., preferably about 250 to 350 ° C. in the air.

焼成時間は、焼成温度等に応じて適宜決定すればよいが、通常１０〜１８０分程度、好ましくは３０〜１５０分程度とすればよい。   The firing time may be appropriately determined according to the firing temperature or the like, but is usually about 10 to 180 minutes, preferably about 30 to 150 minutes.

焼成後の導電性多孔質層の厚みは、特に制限はなく、通常１〜１００μｍ、好ましくは５〜５０μｍ程度である。この範囲の厚みとすることにより、より良好なガス透過性・拡散性及び導電性が得られる。   There is no restriction | limiting in particular in the thickness of the electroconductive porous layer after baking, Usually, 1-100 micrometers, Preferably it is about 5-50 micrometers. By setting the thickness within this range, better gas permeability / diffusibility and conductivity can be obtained.

分散剤は、ガス拡散層（ＧＤＬ）の焼成時に熱分解されるため、分散剤を使用する場合でも焼結後のガス拡散層中には分散剤は存在しないことがある。撥水性樹脂は、焼成後に溶解し、導電性多孔質基材の繊維上及び導電性多孔質層中の導電性炭素粒子、導電性炭素繊維上に付着した状態になっている。   Since the dispersant is thermally decomposed when the gas diffusion layer (GDL) is fired, the dispersant may not be present in the sintered gas diffusion layer even when the dispersant is used. The water-repellent resin is dissolved after firing and is in a state of adhering onto the conductive porous substrate fibers, and the conductive carbon particles and conductive carbon fibers in the conductive porous layer.

また、ここで作製された導電性多孔質層の水に対する接触角は１００°〜１７０°程度、好ましくは１３０°〜１６０°程度とすればよい。なお、導電性多孔質層−水間での接触角は、例えば、自動接触角測定器（協和界面科学製、「ＦＡＣＥ ＣＡ−Ｘ」等）を用い、１マイクロリットル程度の水滴を導電性多孔質層表面に滴下し、３０秒後の接触角を観測すること等により求められる。   Moreover, the contact angle with respect to the water of the electroconductive porous layer produced here may be about 100 ° to 170 °, preferably about 130 ° to 160 °. The contact angle between the conductive porous layer and water is, for example, an automatic contact angle measuring device (manufactured by Kyowa Interface Science, “FACE CA-X”, etc.), and a water droplet of about 1 microliter is conductively porous. It is calculated | required by dripping on the surface of a quality layer and observing the contact angle 30 seconds after.

本発明によれば、導電性多孔質層中にガス拡散性に有効な膜構造を形成するガス拡散層を提供できる。以上の内容から、本発明のガス拡散層を用いることで、優れた電池性能を有する固体高分子形燃料電池を得ることができる。   ADVANTAGE OF THE INVENTION According to this invention, the gas diffusion layer which forms the film | membrane structure effective in gas diffusibility in an electroconductive porous layer can be provided. From the above contents, a polymer electrolyte fuel cell having excellent battery performance can be obtained by using the gas diffusion layer of the present invention.

図１は、実施例１〜５及び比較例１〜６の導電性多孔質層形成用ペースト組成物の細孔径分布を示すグラフである。FIG. 1 is a graph showing the pore size distribution of the conductive porous layer forming paste compositions of Examples 1 to 5 and Comparative Examples 1 to 6. 図２は、実施例１のガス拡散層に形成された導電性多孔質層の表面状態を示す顕微鏡写真である。2 is a photomicrograph showing the surface state of the conductive porous layer formed in the gas diffusion layer of Example 1. FIG. 図３は、実施例３のガス拡散層に形成された導電性多孔質層の表面状態を示す顕微鏡写真である。FIG. 3 is a photomicrograph showing the surface state of the conductive porous layer formed in the gas diffusion layer of Example 3. 図４は、比較例１のガス拡散層に形成された導電性多孔質層の表面状態を示す顕微鏡写真である。4 is a photomicrograph showing the surface state of the conductive porous layer formed in the gas diffusion layer of Comparative Example 1. FIG. 図５は、比較例３のガス拡散層に形成された導電性多孔質層の表面状態を示す顕微鏡写真である。FIG. 5 is a photomicrograph showing the surface state of the conductive porous layer formed in the gas diffusion layer of Comparative Example 3. 図６は、比較例６のガス拡散層に形成された導電性多孔質層の表面状態を示す顕微鏡写真である。6 is a photomicrograph showing the surface state of the conductive porous layer formed in the gas diffusion layer of Comparative Example 6. FIG. 図７は、実施例１のガス拡散層に形成された導電性多孔質層の断面画像を示す走査型電子顕微鏡写真である。7 is a scanning electron micrograph showing a cross-sectional image of the conductive porous layer formed in the gas diffusion layer of Example 1. FIG.

以下に実施例及び比較例を挙げて、本発明をより詳細に説明する。なお、本発明は、以下の実施例に限定されるものではない。   Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

＜材料＞
導電性多孔質層形成用ペースト組成物の調製には、以下に示す材料を使用した。
導電性炭素粒子：ファーネスブラック（バルカンｘｃ７２Ｒ：キャボット社製）、平均分子量１０００〜３０００
フッ素系樹脂（１）：ポリテトラフルオロエチレン（ＰＴＦＥ）（ＡＤ９１１Ｌ：旭硝子（株）製、数平均分子量：２００万〜４００万
フッ素系樹脂（２）：ポリテトラフルオロエチレン（ＰＴＦＥ）（ルブロンＬＤＷ−４１０、：ダイキン工業（株）製）、数平均分子量：５万〜３０万
フッ素系樹脂（３）：ポリテトラフルオロエチレン（ＰＴＦＥ）（ＰＴＦＥ３１−ＪＲ：Dupont製）、数平均分子量：６００万〜９００万
導電性炭素繊維：ＶＧＣＦ（ＶＧＣＦ（登録商標；標準品）：昭和電工（株）製）
分散剤（１）：ポリオキシエチレンジスチレン化フェニルエーテル（エマルゲンＡ６０：花王（株）製）
分散剤（２）：ポリオキシアルキレンアルキルエーテル（エマルゲンＭＳ１１０：花王（株）製）
分散剤（３）：ポリオキシエチレンアルキルアリルエーテル（ノイゲンＥＡ１３７：第一工業製薬（株）製）
分散剤（４）：酸価を含まず、アミン価を含むアニオン系分散剤（ＢＹＫ１８４：ビックケミー製）
分散剤（５）：ポリオキシエチレンアルキルアミン（アミート１０５：花王（株）製） <Material>
For the preparation of the conductive porous layer forming paste composition, the following materials were used.
Conductive carbon particles: Furnace black (Vulcan xc72R: manufactured by Cabot Corporation), average molecular weight 1000 to 3000
Fluorine resin (1): polytetrafluoroethylene (PTFE) (AD911L: manufactured by Asahi Glass Co., Ltd., number average molecular weight: 2 million to 4 million fluorine resin (2): polytetrafluoroethylene (PTFE) (Lublon LDW- 410, manufactured by Daikin Industries, Ltd.), number average molecular weight: 50,000 to 300,000 fluorine-based resin (3): polytetrafluoroethylene (PTFE) (PTFE31-JR: manufactured by Dupont), number average molecular weight: 6 million to 9 million conductive carbon fiber: VGCF (VGCF (registered trademark; standard product): manufactured by Showa Denko KK)
Dispersant (1): polyoxyethylene distyrenated phenyl ether (Emulgen A60: manufactured by Kao Corporation)
Dispersant (2): polyoxyalkylene alkyl ether (Emulgen MS110: manufactured by Kao Corporation)
Dispersant (3): polyoxyethylene alkyl allyl ether (Neugen EA137: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
Dispersant (4): Anionic dispersant not containing acid value but containing amine value (BYK184: manufactured by BYK Chemie)
Dispersant (5): polyoxyethylene alkylamine (Amate 105: manufactured by Kao Corporation)

実施例１〜５及び比較例１〜８
＜実施例１＞
導電性炭素粒子１００重量部、ＶＧＣＦ３５重量部、分散剤（分散剤（１）；エマルゲンＡ６０）２５重量部及び水８８０重量部、エタノール１０重量部をスターラー分散で３０分分散した後、フッ素系樹脂２７０重量部（フッ素系樹脂（１）；ＡＤ９１１Ｌ）を加えて攪拌機（ＥＹＥＬＡ製ＭＡＺＥＬＡ、攪拌羽の半径：２ｃｍ）により周速０．３１４ｍ／ｓで３０分攪拌させることにより導電性多孔質層形成用ペースト組成物を調合した。 Examples 1-5 and Comparative Examples 1-8
<Example 1>
100 parts by weight of conductive carbon particles, 35 parts by weight of VGCF, 25 parts by weight of a dispersant (dispersant (1); Emulgen A60), 880 parts by weight of water, and 10 parts by weight of ethanol are dispersed by stirrer dispersion for 30 minutes, and then a fluororesin 270 parts by weight (fluorine resin (1); AD911L) was added and the mixture was stirred for 30 minutes at a peripheral speed of 0.314 m / s with a stirrer (MAZELA manufactured by EYELA, stirring blade radius: 2 cm) to form a conductive porous layer A paste composition was prepared.

＜実施例２＞
導電性炭素粒子１００重量部、ＶＧＣＦ３５重量部、分散剤（分散剤（１）；エマルゲンＡ６０）５０重量部及び水８１０重量部、エタノール１０重量部をスターラー分散で３０分分散した後、フッ素系樹脂２７０重量部（フッ素系樹脂（１）；ＡＤ９１１Ｌ）を加えて攪拌機（ＥＹＥＬＡ製ＭＡＺＥＬＡ、攪拌羽の半径：２ｃｍ）により周速０．３１４ｍ／ｓで３０分攪拌させることにより導電性多孔質層形成用ペースト組成物を調合した。 <Example 2>
100 parts by weight of conductive carbon particles, 35 parts by weight of VGCF, 50 parts by weight of a dispersant (dispersant (1); Emulgen A60), 810 parts by weight of water, and 10 parts by weight of ethanol are dispersed by a stirrer for 30 minutes, and then a fluororesin 270 parts by weight (fluorine resin (1); AD911L) was added and the mixture was stirred for 30 minutes at a peripheral speed of 0.314 m / s with a stirrer (MAZELA manufactured by EYELA, stirring blade radius: 2 cm) to form a conductive porous layer A paste composition was prepared.

＜実施例３＞
導電性炭素粒子１００重量部、ＶＧＣＦ３５重量部、分散剤（分散剤（１）；エマルゲンＡ６０）７５重量部及び水７４５重量部、エタノール１０重量部をスターラー分散で３０分分散した後、フッ素系樹脂２７０重量部（フッ素系樹脂（１）；ＡＤ９１１Ｌ）を加えて攪拌機（ＥＹＥＬＡ製ＭＡＺＥＬＡ、攪拌羽の半径：２ｃｍ）により周速０．３１４ｍ／ｓで３０分攪拌させることにより導電性多孔質層形成用ペースト組成物を調合した。 <Example 3>
100 parts by weight of conductive carbon particles, 35 parts by weight of VGCF, 75 parts by weight of a dispersant (dispersant (1); Emulgen A60), 745 parts by weight of water, and 10 parts by weight of ethanol are dispersed by stirrer dispersion for 30 minutes, and then a fluororesin 270 parts by weight (fluorine resin (1); AD911L) was added and the mixture was stirred for 30 minutes at a peripheral speed of 0.314 m / s with a stirrer (MAZELA manufactured by EYELA, stirring blade radius: 2 cm) to form a conductive porous layer A paste composition was prepared.

＜実施例４＞
導電性炭素粒子１００重量部、ＶＧＣＦ３５重量部、分散剤（分散剤（２）；エマルゲンＭＳ１１０）２５重量部及び水８８０重量部、エタノール１０重量部をスターラー分散で３０分分散した後、フッ素系樹脂２７０重量部（フッ素系樹脂（１）；ＡＤ９１１Ｌ）を加えて攪拌機（ＥＹＥＬＡ製ＭＡＺＥＬＡ、攪拌羽の半径：２ｃｍ）により周速０．３１４ｍ／ｓで３０分攪拌させることにより導電性多孔質層形成用ペースト組成物を調合した。 <Example 4>
100 parts by weight of conductive carbon particles, 35 parts by weight of VGCF, 25 parts by weight of a dispersant (dispersant (2); Emulgen MS110), 880 parts by weight of water, and 10 parts by weight of ethanol are dispersed by a stirrer for 30 minutes, and then a fluororesin 270 parts by weight (fluorine resin (1); AD911L) was added and the mixture was stirred for 30 minutes at a peripheral speed of 0.314 m / s with a stirrer (MAZELA manufactured by EYELA, stirring blade radius: 2 cm) to form a conductive porous layer A paste composition was prepared.

＜実施例５＞
導電性炭素粒子１００重量部、ＶＧＣＦ３５重量部、分散剤（分散剤（３）；ノイゲンＥＡ１３７）２５重量部及び水８８０重量部、エタノール１０重量部をスターラー分散で３０分分散した後、フッ素系樹脂２７０重量部（フッ素系樹脂（１）；ＡＤ９１１Ｌ）を加えて攪拌機（ＥＹＥＬＡ製ＭＡＺＥＬＡ、攪拌羽の半径：２ｃｍ）により周速０．３１４ｍ／ｓで３０分攪拌させることにより導電性多孔質層形成用ペースト組成物を調合した。 <Example 5>
100 parts by weight of conductive carbon particles, 35 parts by weight of VGCF, 25 parts by weight of a dispersant (dispersant (3); Neugen EA137), 880 parts by weight of water, and 10 parts by weight of ethanol are dispersed by stirrer dispersion for 30 minutes, and then a fluororesin 270 parts by weight (fluorine resin (1); AD911L) was added and the mixture was stirred for 30 minutes at a peripheral speed of 0.314 m / s with a stirrer (MAZELA manufactured by EYELA, stirring blade radius: 2 cm) to form a conductive porous layer A paste composition was prepared.

＜比較例１＞
導電性炭素粒子１００重量部、ＶＧＣＦ３５重量部、分散剤（分散剤（４）；ＢＹＫ−１８４）２５重量部及び水８８０重量部をスターラー分散で３０分分散した後、フッ素系樹脂２７０重量部（フッ素系樹脂（１）；ＡＤ９１１Ｌ）を加えて攪拌機（ＥＹＥＬＡ製ＭＡＺＥＬＡ、攪拌羽の半径：２ｃｍ）により周速０．３１４ｍ／ｓで３０分攪拌させることにより導電性多孔質層形成用ペースト組成物を調合した。 <Comparative Example 1>
100 parts by weight of conductive carbon particles, 35 parts by weight of VGCF, 25 parts by weight of a dispersant (dispersant (4); BYK-184) and 880 parts by weight of water are dispersed by a stirrer for 30 minutes, and then 270 parts by weight of a fluororesin ( Fluorine-based resin (1); AD911L) was added, and the mixture was stirred for 30 minutes at a peripheral speed of 0.314 m / s with a stirrer (MAZELA manufactured by EYELA, stirring blade radius: 2 cm), and the conductive porous layer forming paste composition Was formulated.

＜比較例２＞
導電性炭素粒子１００重量部、ＶＧＣＦ３５重量部、分散剤（分散剤（４）；ＢＹＫ−１８４）５０重量部及び水８１０重量部をスターラー分散で３０分分散した後、フッ素系樹脂２７０重量部（フッ素系樹脂（１）；ＡＤ９１１Ｌ）を加えて攪拌機（ＥＹＥＬＡ製ＭＡＺＥＬＡ、攪拌羽の半径：２ｃｍ）により周速０．３１４ｍ／ｓで３０分攪拌させることにより導電性多孔質層形成用ペースト組成物を調合した。 <Comparative Example 2>
100 parts by weight of conductive carbon particles, 35 parts by weight of VGCF, 50 parts by weight of a dispersant (dispersant (4); BYK-184) and 810 parts by weight of water were dispersed for 30 minutes by stirrer dispersion, and then 270 parts by weight of a fluororesin ( Fluorine-based resin (1); AD911L) was added, and the mixture was stirred for 30 minutes at a peripheral speed of 0.314 m / s with a stirrer (MAZELA manufactured by EYELA, stirring blade radius: 2 cm), and the conductive porous layer forming paste composition Was formulated.

＜比較例３＞
導電性炭素粒子１００重量部、ＶＧＣＦ３５重量部、分散剤（分散剤（４）；ＢＹＫ−１８４）７５重量部及び水７４５重量部をスターラー分散で３０分分散した後、フッ素系樹脂２７０重量部（フッ素系樹脂（１）；ＡＤ９１１Ｌ）を加えて攪拌機（ＥＹＥＬＡ製ＭＡＺＥＬＡ、攪拌羽の半径：２ｃｍ）により周速０．３１４ｍ／ｓで３０分攪拌させることにより導電性多孔質層形成用ペースト組成物を調合した。 <Comparative Example 3>
100 parts by weight of conductive carbon particles, 35 parts by weight of VGCF, 75 parts by weight of a dispersant (dispersant (4); BYK-184) and 745 parts by weight of water are dispersed by a stirrer for 30 minutes, and then 270 parts by weight of a fluororesin ( Fluorine-based resin (1); AD911L) was added, and the mixture was stirred for 30 minutes at a peripheral speed of 0.314 m / s with a stirrer (MAZELA manufactured by EYELA, stirring blade radius: 2 cm), and the conductive porous layer forming paste composition Was formulated.

＜比較例４＞
導電性炭素粒子１００重量部、ＶＧＣＦ３５重量部、分散剤（分散剤（５）；アミート１０５）２５重量部及び水８８０重量部をスターラー分散で３０分分散した後、フッ素系樹脂２７０重量部（フッ素系樹脂（１）；ＡＤ９１１Ｌ）を加えて攪拌機（ＥＹＥＬＡ製ＭＡＺＥＬＡ、攪拌羽の半径：２ｃｍ）により周速０．３１４ｍ／ｓで３０分攪拌させることにより導電性多孔質層形成用ペースト組成物を調合した。 <Comparative Example 4>
100 parts by weight of conductive carbon particles, 35 parts by weight of VGCF, 25 parts by weight of a dispersant (dispersant (5); Amite 105) and 880 parts by weight of water are dispersed by a stirrer dispersion for 30 minutes, and then 270 parts by weight of a fluororesin (fluorine) System resin (1); AD911L) and stirring with a stirrer (MAZELA made by EYELA, stirring blade radius: 2 cm) at a peripheral speed of 0.314 m / s for 30 minutes to obtain a conductive porous layer forming paste composition Prepared.

＜比較例５＞
導電性炭素粒子１００重量部、ＶＧＣＦ３５重量部、分散剤（分散剤（５）；アミート１０５）５０重量部及び水８１０重量部をスターラー分散で３０分分散した後、フッ素系樹脂２７０重量部（フッ素系樹脂（１）；ＡＤ９１１Ｌ）を加えて攪拌機（ＥＹＥＬＡ製ＭＡＺＥＬＡ、攪拌羽の半径：２ｃｍ）により周速０．３１４ｍ／ｓで３０分攪拌させることにより導電性多孔質層形成用ペースト組成物を調合した。 <Comparative Example 5>
100 parts by weight of conductive carbon particles, 35 parts by weight of VGCF, 50 parts by weight of a dispersant (dispersant (5); Amite 105) and 810 parts by weight of water were dispersed for 30 minutes by stirrer dispersion, and then 270 parts by weight of fluorine resin (fluorine) System resin (1); AD911L) and stirring with a stirrer (MAZELA made by EYELA, stirring blade radius: 2 cm) at a peripheral speed of 0.314 m / s for 30 minutes to obtain a conductive porous layer forming paste composition Prepared.

＜比較例６＞
導電性炭素粒子１００重量部、ＶＧＣＦ３５重量部、分散剤（分散剤（５）；アミート１０５）７５重量部及び水７４５重量部をスターラー分散で３０分分散した後、フッ素系樹脂２７０重量部（フッ素系樹脂（１）；ＡＤ９１１Ｌ）を加えて攪拌機（ＥＹＥＬＡ製ＭＡＺＥＬＡ、攪拌羽の半径：２ｃｍ）により周速０．３１４ｍ／ｓで３０分攪拌させることにより導電性多孔質層形成用ペースト組成物を調合した。 <Comparative Example 6>
100 parts by weight of conductive carbon particles, 35 parts by weight of VGCF, 75 parts by weight of a dispersant (dispersant (5); Amite 105) and 745 parts by weight of water were dispersed by a stirrer dispersion for 30 minutes, and then 270 parts by weight of a fluorine-based resin (fluorine) System resin (1); AD911L) and stirring with a stirrer (MAZELA made by EYELA, stirring blade radius: 2 cm) at a peripheral speed of 0.314 m / s for 30 minutes to obtain a conductive porous layer forming paste composition Prepared.

＜比較例７＞
導電性炭素粒子１００重量部、ＶＧＣＦ３５重量部、分散剤（分散剤（１）；エマルゲンＡ６０）２５重量部及び水８８０重量部、エタノール１０重量部をスターラー分散で３０分分散した後、フッ素系樹脂２７０重量部（フッ素系樹脂（２）；ルブロンＬＤＷ−４１０）を加えて攪拌機（ＥＹＥＬＡ製ＭＡＺＥＬＡ、攪拌羽の半径：２ｃｍ）により周速０．３１４ｍ／ｓで３０分攪拌させることにより導電性多孔質層形成用ペースト組成物を調合した。 <Comparative Example 7>
100 parts by weight of conductive carbon particles, 35 parts by weight of VGCF, 25 parts by weight of a dispersant (dispersant (1); Emulgen A60), 880 parts by weight of water, and 10 parts by weight of ethanol are dispersed by stirrer dispersion for 30 minutes, and then a fluororesin 270 parts by weight (fluorine resin (2); Lubron LDW-410) was added, and the mixture was stirred for 30 minutes at a peripheral speed of 0.314 m / s with a stirrer (MAZELA manufactured by EYELA, stirring blade radius: 2 cm). A paste composition for forming a layer was prepared.

＜比較例８＞
導電性炭素粒子１００重量部、ＶＧＣＦ３５重量部、分散剤（分散剤（１）；エマルゲンＡ６０）２５重量部及び水８８０重量部、エタノール１０重量部をスターラー分散で３０分分散した後、フッ素系樹脂２７０重量部（フッ素系樹脂（３）；ＰＴＦＥ３１−ＪＲ）を加えて攪拌機（ＥＹＥＬＡ製ＭＡＺＥＬＡ、攪拌羽の半径：２ｃｍ）により周速０．３１４ｍ／ｓで３０分攪拌させることにより導電性多孔質層形成用ペースト組成物を調合した。 <Comparative Example 8>
100 parts by weight of conductive carbon particles, 35 parts by weight of VGCF, 25 parts by weight of a dispersant (dispersant (1); Emulgen A60), 880 parts by weight of water, and 10 parts by weight of ethanol are dispersed by stirrer dispersion for 30 minutes, and then a fluororesin 270 parts by weight (fluorine resin (3); PTFE31-JR) was added, and the mixture was stirred for 30 minutes at a peripheral speed of 0.314 m / s with a stirrer (MAZELA made by EYELA, stirring blade radius: 2 cm). A paste composition for layer formation was prepared.

実施例１〜５及び比較例１〜８の配合割合を表１に示す。   Table 1 shows the blending ratios of Examples 1 to 5 and Comparative Examples 1 to 8.

＜撥水処理＞
導電性多孔質基材にはカーボンペーパー（ＴＧＰ−Ｈ−６０：東レ（株）製）を用い、水１００重量部に対して、ＰＴＦＥ懸濁液（ＰＴＦＥ懸濁液１００重量部は、ＰＴＦＥ６０重量部、分散剤（ポリオキシエチレンアルキレンアルキルエーテル）３重量部及び水３７重量から構成）５重量部を混合させたＰＴＦＥ水分散液に２分間含浸させた後、大気雰囲気中９５度で１５分程度乾燥させ、次いで大気雰囲気中約３００℃で２時間程焼成を行うことにより、撥水処理を施した。 <Water repellent treatment>
Carbon paper (TGP-H-60: manufactured by Toray Industries, Inc.) is used as the conductive porous substrate, and PTFE suspension (100 parts by weight of PTFE suspension is 60 parts by weight of PTFE) with respect to 100 parts by weight of water. 2 parts impregnated with a PTFE aqueous dispersion mixed with 5 parts by weight, 3 parts by weight of a dispersant (polyoxyethylene alkylene alkyl ether) and 37 parts by weight of water), and then at 95 ° C. for about 15 minutes. It was dried and then baked at about 300 ° C. for about 2 hours in an air atmosphere to give a water repellent treatment.

＜細孔径分布測定＞
実施例１〜５及び比較例１〜８で調製した各導電性多孔質層形成用ペースト組成物の細孔径分布の測定結果を図１に示す。細孔径分布は、自動ポロシメーター オートポアＩＶ９５００（（株）島津製作所製）を用い、サンプル内に圧入された水銀量から測定する。 <Measurement of pore size distribution>
The measurement results of the pore diameter distribution of each conductive porous layer forming paste composition prepared in Examples 1 to 5 and Comparative Examples 1 to 8 are shown in FIG. The pore size distribution is measured from the amount of mercury injected into the sample using an automatic porosimeter, Autopore IV9500 (manufactured by Shimadzu Corporation).

ガス拡散層の製造
実施例１〜５及び比較例１〜８で調製した各導電性多孔質層形成用ペースト組成物を、アプリケーター（Ｓｈｅｅｎ Ｉｎｓｔｒｕｍｅｎｔｓ Ｌｔｄ製、「Ｍｉｃｒｏｍｅｔｅｒ Ａｄｊｕｓｔａｂｌｅ Ｆｉｌｍ Ａｐｐｌｉｃａｔｏｒ、１１１７／２００」）を用いて塗工量が固形分換算で、３０ｇ／ｍ２になるように、上記撥水処理済み導電性多孔質基材の一方の面に均一に塗工した。次いで、大気雰囲気中９５℃で２０分乾燥した後、大気雰囲気中３００℃で２時間焼成することにより、導電性多孔質基材表面に導電性多孔質層（ＭＰＬ）が形成された、ガス拡散層（実施例１〜５及び比較例１〜８のペースト組成物を用いて製造したガス拡散層）を製造した。 Production of Gas Diffusion Layer Each conductive porous layer forming paste composition prepared in Examples 1 to 5 and Comparative Examples 1 to 8 was applied to an applicator (manufactured by Sheen Instruments Ltd., “Micrometer Adjustable Film Applicator, 1117/200”). Was applied uniformly on one surface of the water-repellent treated conductive porous substrate so that the coating amount was 30 g / m 2 in terms of solid content. Next, after drying at 95 ° C. for 20 minutes in the air atmosphere, the conductive porous layer (MPL) was formed on the surface of the conductive porous substrate by firing at 300 ° C. for 2 hours in the air atmosphere. A layer (a gas diffusion layer produced using the paste compositions of Examples 1 to 5 and Comparative Examples 1 to 8) was produced.

ここで、比較例７のペースト組成物を使用して導電性多孔質基材上に導電性多孔質層を形成した場合、導電性多孔質層‐導電性多孔質基材間での結着性が悪いことと、多数のクラックが発生することにより膜剥れが生じ、導電性多孔質層を安定的に形成することが困難であった。   Here, when the conductive porous layer is formed on the conductive porous substrate using the paste composition of Comparative Example 7, the binding property between the conductive porous layer and the conductive porous substrate. However, it was difficult to form a conductive porous layer stably because the film was peeled off due to the badness and the generation of many cracks.

また、比較例８のペースト組成物を作製した場合は、撥水性樹脂の繊維化が著しくペースト組成物中に多数の凝集物が生じ、この凝集物が存在するために成膜性の良い導電性多孔質層を形成することが困難であった。   In addition, when the paste composition of Comparative Example 8 was prepared, the water-repellent resin was very fiberized and a large number of aggregates were formed in the paste composition. It was difficult to form a porous layer.

ガス拡散層の評価試験
＜導電性多孔質層表面観察＞
実施例１及び３、並びに比較例１、３及び６のガス拡散層に形成された導電性多孔質層を、ＨＩＢＲＩＤ ＭＩＣＲＯ ＳＣＯＰＥ ＳＨ−４５００（ＨｉＲＯＸ社製）により観察した。結果を図２〜６に示す。なお、図２は実施例１、図３は実施例３、図４は比較例１、図５は比較例３、図６は比較例６の表面状態を示す。 Evaluation test of gas diffusion layer <Conductive porous layer surface observation>
The conductive porous layers formed in the gas diffusion layers of Examples 1 and 3 and Comparative Examples 1, 3 and 6 were observed with HIBRID MICRO SCOPE SH-4500 (manufactured by HiROX). The results are shown in FIGS. 2 shows the surface state of Example 1, FIG. 3 shows Example 3, FIG. 4 shows Comparative Example 1, FIG. 5 shows Comparative Example 3, and FIG.

また、導電性多孔質層上に発生したクラックの占有面積をＩＭＡＧＥ−ＰＲＯ ＰＬＵＳ（（株）プラネトロン製）を使用して、クラック部とそれ以外の部分を二値化することで測定した。導電性多孔質層でのクラックの面積比について表２に示す。   Moreover, the occupied area of the crack which generate | occur | produced on the electroconductive porous layer was measured by binarizing a crack part and other parts using IMAGE-PRO PLUS (made by Planetron Co., Ltd.). Table 2 shows the area ratio of cracks in the conductive porous layer.

＜導電性多孔質層断面観察＞
導電性多孔質層中の撥水性樹脂の繊維化の状況については、導電性多孔質層の断面画像を走査型顕微鏡により観察することにより判断した。実施例１の導電性多孔質層中の撥水性樹脂の繊維化状況について、図７に示す。 <Conductive porous layer cross-sectional observation>
The state of fiber formation of the water-repellent resin in the conductive porous layer was judged by observing a cross-sectional image of the conductive porous layer with a scanning microscope. FIG. 7 shows the fiberization state of the water-repellent resin in the conductive porous layer of Example 1.

＜ガス透過性・拡散性＞
貫通孔測定装置（ＣＦＰ−１２００−ＡＥＬ、ＰＭＩ社製）を使用して、実際の電池評価時で採用しているガス透過圧０．３ＭＰａの条件下での実施例１〜５及び比較例１〜６で作製したガス拡散層のガス透過量を測定した結果を表２に示す。この結果から、クラック占有面積が増加するに従いガス透過量が増加する傾向が得られた。 <Gas permeability / diffusivity>
Examples 1 to 5 and Comparative Example 1 under the conditions of a gas permeation pressure of 0.3 MPa, which are employed in actual battery evaluation, using a through-hole measuring device (CFP-1200-AEL, manufactured by PMI) Table 2 shows the results of measuring the gas permeation amount of the gas diffusion layers prepared in -6. From this result, there was a tendency that the gas permeation amount increased as the crack occupation area increased.

＜細孔径分布＞
実施例１〜５及び比較例１〜６の導電性多孔質基材上に形成した導電性多孔質層の細孔径分布は、自動ポロシメーター オートポアＩＶ９５００（（株）島津製作所製）を利用して測定した。段落［００３７］に記載の通り、導電性多孔質層が支配的な由来の細孔経分布は２５〜１０００ｎｍと考えられるため、段落［００３７］に記載の算出方法によりこの導電性多孔質層の細孔径分布内の細孔容積の総和と導電性多孔質層のみの重量との関係を計算した結果を表２に示す（ＭＰＬ由来の細孔容積の和）。 <Pore size distribution>
The pore size distribution of the conductive porous layers formed on the conductive porous substrates of Examples 1 to 5 and Comparative Examples 1 to 6 was measured using an automatic porosimeter Autopore IV9500 (manufactured by Shimadzu Corporation). did. As described in Paragraph [0037], the pore size distribution from which the conductive porous layer is dominant is considered to be 25 to 1000 nm. Therefore, the calculation method described in Paragraph [0037] The results of calculating the relationship between the total pore volume in the pore size distribution and the weight of the conductive porous layer alone are shown in Table 2 (sum of pore volumes derived from MPL).

電解質膜−触媒層積層体の製造
白金触媒担持炭素粒子４ｇ（田中貴金属工業（株）製、「ＴＥＣ１０Ｅ５０Ｅ」）、イオン伝導性高分子電解質膜溶液４０ｇ（Ｎａｆｉｏｎ５ｗｔ％溶液：「ＤＥ−５２０」デュポン社製）、蒸留水１２ｇ、ｎ−ブタノール２０ｇ及びｔ−ブタノール２０ｇを配合し、分散機にて攪拌混合することにより、アノード触媒層形成用ペースト組成物及びカソード触媒層形成用ペースト組成物を得た。 Production of electrolyte membrane-catalyst layer laminate 4 g of platinum catalyst-supported carbon particles (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., “TEC10E50E”), 40 g of ion conductive polymer electrolyte membrane solution (Nafion 5 wt% solution: “DE-520” DuPont) Manufactured), 12 g of distilled water, 20 g of n-butanol and 20 g of t-butanol were mixed and stirred and mixed in a disperser to obtain a paste composition for forming an anode catalyst layer and a paste composition for forming a cathode catalyst layer. .

アノード触媒層形成用ペースト組成物及びカソード触媒層形成用ペースト組成物を、それぞれアプリケーターを用いて転写基材（材質：ポリエチレンテレフタラートフィルム）上に塗工し、９５℃で３０分程度乾燥させることにより触媒層を形成させて、アノード触媒層形成用転写シート及びカソード触媒層形成用転写シートを作製した。なお、触媒層の塗工量は、アノード触媒層、カソード触媒層共に白金担持量が０．４５ｍｇ／ｃｍ２程度となるようにした。 The anode catalyst layer forming paste composition and the cathode catalyst layer forming paste composition are each coated on a transfer substrate (material: polyethylene terephthalate film) using an applicator and dried at 95 ° C. for about 30 minutes. A catalyst layer was formed by the above, and an anode catalyst layer forming transfer sheet and a cathode catalyst layer forming transfer sheet were prepared. The coating amount of the catalyst layer was such that the platinum loading amount was about 0.45 mg / cm 2 for both the anode catalyst layer and the cathode catalyst layer.

上記で作製したアノード触媒層形成用転写シート及びカソード触媒層形成用転写シートを用いて、電解質膜各面に、熱プレスを行った後、転写基材のみを剥がすことにより、電解質膜−触媒層積層体を作製した。   Using the anode catalyst layer-forming transfer sheet and cathode catalyst layer-forming transfer sheet prepared above, each surface of the electrolyte membrane was hot pressed, and then only the transfer substrate was peeled off, so that the electrolyte membrane-catalyst layer A laminate was produced.

燃料電池の製造
上記で作製した電解質膜−触媒層積層体の片面（カソード側）に、実施例１〜５及び比較例１〜６の各ガス拡散層を、導電性多孔質層が触媒層に接触するように積層させることにより、電解質膜−電極接合体（ＭＥＡ）を得、次いで、得られたＭＥＡを燃料電池セルに組み込むことにより、固体高分子形燃料電池（実施例１〜５及び比較例１〜６のガス拡散層を用いて製造した固体高分子形燃料電池）を製造した。 Production of Fuel Cell The gas diffusion layers of Examples 1 to 5 and Comparative Examples 1 to 6 are formed on one side (cathode side) of the electrolyte membrane-catalyst layer laminate produced as described above, and the conductive porous layer is used as the catalyst layer. An electrolyte membrane-electrode assembly (MEA) is obtained by laminating so as to be in contact with each other, and then the obtained MEA is incorporated into a fuel cell to obtain a polymer electrolyte fuel cell (Examples 1 to 5 and comparison) A polymer electrolyte fuel cell manufactured using the gas diffusion layers of Examples 1 to 6) was manufactured.

燃料電池の評価試験
＜電池性能評価＞
上記で作製した実施例１〜５及び比較例１〜６のＭＥＡを使用し、電池性能評価を以下の条件により行った。 Fuel cell evaluation test <Battery performance evaluation>
Using the MEAs of Examples 1 to 5 and Comparative Examples 1 to 6 prepared above, battery performance evaluation was performed under the following conditions.

セル温度：８０℃
加湿温度：カソード６５℃、アノード６５℃
ガス利用率：カソード４０％、アノード７０％
ガス透過圧：０．３ＭＰａ
セル面積：２５ｃｍ２
負荷電流を０．０５Ａ／ｃｍ２〜１Ａ／ｃｍ２まで変動させた時の１Ａ／ｃｍ２のセル電圧値とクラック占有率及び細孔容積値について表２に示した。 Cell temperature: 80 ° C
Humidification temperature: cathode 65 ° C, anode 65 ° C
Gas utilization rate: cathode 40%, anode 70%
Gas permeation pressure: 0.3 MPa
Cell area: 25 cm 2
Table 2 shows the load current 0.05A / cm 2 ~1A / cm cell voltage value of 1A / cm 2 when varied to 2 and crack occupancy and pore volume values.

比較例１〜３では、クラック占有面積が実施例と遜色無く存在するが、ＭＰＬ由来の細孔容積が小さくガス拡散性能が良好に保てず、実施例と比較すると発電性能が低下した。また、比較例４〜６では、ＭＰＬ由来の細孔容積は実施例と遜色無い値が得られているが、クラック占有面積が小さく反応に必要なガス透過量が得られずに、実施例と比較すると発電性能が低下した。なお、比較例７及び８については、上述のとおり導電性多孔質層の成膜が困難なため、評価できなかった。   In Comparative Examples 1 to 3, the crack occupying area was inferior to that of the example, but the pore volume derived from MPL was small and the gas diffusion performance could not be kept good, and the power generation performance was reduced as compared with the example. Further, in Comparative Examples 4 to 6, the MPL-derived pore volume was inferior to that of the Example, but the crack occupying area was small and the gas permeation required for the reaction could not be obtained. In comparison, power generation performance decreased. Note that Comparative Examples 7 and 8 could not be evaluated because it was difficult to form a conductive porous layer as described above.

Claims (10)

導電性多孔質基材上に、導電性多孔質層が形成された固体高分子形燃料電池用ガス拡散層であって、
前記導電性多孔質層は、少なくとも導電性炭素粒子、及び撥水性樹脂を含み、
前記導電性多孔質層は、細孔径が２５〜１０００ｎｍの細孔容積の和が１．４ｍｌ／ｇ以上であり、且つ、クラック占有面積が０．８％〜２．５％であり、
前記撥水性樹脂の数平均分子量が、１００万より大きく、５００万より小さい、固体高分子形燃料電池用ガス拡散層。 A gas diffusion layer for a polymer electrolyte fuel cell in which a conductive porous layer is formed on a conductive porous substrate,
The conductive porous layer, seen containing at least conductive carbon particles, and a water-repellent resins,
The conductive porous layer, the pore diameter is at the sum of the pore volume of 25~1000nm is 1.4 ml / g or more, and crack area occupied Ri 0.8% to 2.5% der,
A gas diffusion layer for a polymer electrolyte fuel cell , wherein the water repellent resin has a number average molecular weight of greater than 1 million and less than 5 million . 前記導電性多孔質層は、さらに、分散剤を含む、請求項１に記載の固体高分子形燃料電池用ガス拡散層。The gas diffusion layer for a polymer electrolyte fuel cell according to claim 1, wherein the conductive porous layer further contains a dispersant. 分散剤がノニオン系分散剤である、請求項１又は２に記載の固体高分子形燃料電池用ガス拡散層。 The gas diffusion layer for a polymer electrolyte fuel cell according to claim 1 or 2, wherein the dispersant is a nonionic dispersant. さらに、導電性炭素繊維を含む、請求項１〜３のいずれかに記載の固体高分子形燃料電池用ガス拡散層。 Furthermore, the gas diffusion layer for polymer electrolyte fuel cells according to any one of claims 1 to 3, further comprising conductive carbon fibers. 前記撥水性樹脂は、繊維化していない、請求項１〜４のいずれかに記載の固体高分子形燃料電池用ガス拡散層。 The water-repellent resin is not fiber維化, a polymer electrolyte fuel cell gas diffusion layer according to any one of claims 1 to 4. 前記導電性多孔質基材は、カーボンペーパー、カーボンクロス、又はカーボン不織布である、請求項１〜５のいずれかに記載の固体高分子形燃料電池用ガス拡散層。 The gas diffusion layer for a polymer electrolyte fuel cell according to any one of claims 1 to 5, wherein the conductive porous substrate is carbon paper, carbon cloth, or carbon nonwoven fabric. 請求項１〜６のいずれかに記載のガス拡散層を用いた固体高分子形燃料電池。 A polymer electrolyte fuel cell using the gas diffusion layer according to claim 1. 請求項１〜６のいずれかに記載のガス拡散層の製造に用いられる導電性多孔質層形成用ペースト組成物であって、少なくとも導電性炭素粒子、数平均分子量が１００万より大きく５００万より小さい撥水性樹脂、及び分散剤を含む導電性多孔質層形成用ペースト組成物。 A conductive porous layer forming paste composition for use in the production of a gas diffusion layer according to any one of claims 1 to 6, wherein at least conductive carbon particles, the number average molecular weight is greater than 1 million and greater than 5 million. small water-repellent resin, electrically conductive porous layer forming paste composition comprising及beauty dispersing agent. さらに、導電性炭素繊維を含む、請求項８に記載の導電性多孔質層形成用ペースト組成物。 The conductive porous layer forming paste composition according to claim 8, further comprising conductive carbon fibers. 少なくとも導電性炭素粒子、数平均分子量が１００万より大きく５００万より小さい撥水性樹脂、及び分散剤を、０．１〜０．８５ｍ／ｓの周速で攪拌させる工程を備える、請求項８又は９に記載の導電性多孔質層形成用ペースト組成物の製造方法。 Comprising at least conductive carbon particles, step number average molecular weight of 1 million greater than 5 million less water-repellent resin, the及beauty dispersing agent, is stirred at a peripheral speed of 0.1~0.85m / s, according to claim 8 Or 9. A method for producing a conductive porous layer forming paste composition according to 9.
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