WO2015037721A1

WO2015037721A1 - Conductive composite particles, composition for electrode catalyst layer for fuel cell, electrode catalyst layer for fuel cell, and fuel cell

Info

Publication number: WO2015037721A1
Application number: PCT/JP2014/074292
Authority: WO
Inventors: 岳洋米澤; 山崎　和彦; 真也白石; 洋利梅田
Original assignee: 三菱マテリアル株式会社; 三菱マテリアル電子化成株式会社
Priority date: 2013-09-12
Filing date: 2014-09-12
Publication date: 2015-03-19
Also published as: JP2015056286A; JP6226653B2; TW201523993A

Abstract

Conductive composite particles which each comprise a titanium oxide particle and a porous tin oxide microparticle layer that covers the surface of the titanium oxide particle, wherein in a high-resolution transmission electron micrograph, the length of a tin oxide lattice image parallel to a titanium oxide lattice image that is parallel to the surface of the titanium oxide particle is 80% or more of the length of the titanium oxide lattice image.

Description

導電性複合粒子、燃料電池の電極触媒層用組成物、燃料電池の電極触媒層、および燃料電池Conductive composite particles, composition for fuel cell electrode catalyst layer, fuel cell electrode catalyst layer, and fuel cell

　本発明は、酸化チタン(ＴｉＯ_２)粒子の表面に、酸化錫(ＳｎＯ_２)微粒子が形成された導電性複合粒子に関する。この導電性複合粒子は、比表面積が大きく、燃料電池の電極の白金ナノ粒子触媒の担体に適している。また、本発明は、燃料電池の電極触媒層用組成物、燃料電池の電極触媒層、および燃料電池に関する。
　本願は、２０１３年９月１２日に、日本に出願された特願２０１３－１８９０５９号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to conductive composite particles in which tin oxide (SnO ₂ ) fine particles are formed on the surface of titanium oxide (TiO ₂ ) particles. The conductive composite particles have a large specific surface area and are suitable as a support for platinum nanoparticle catalysts of fuel cell electrodes. The present invention also relates to a composition for a fuel cell electrode catalyst layer, a fuel cell electrode catalyst layer, and a fuel cell.
This application claims priority based on Japanese Patent Application No. 2013-189059 filed in Japan on September 12, 2013, the contents of which are incorporated herein by reference.

　現在、環境問題を考慮したエネルギー変換効率が高いエネルギー源として、燃料電池の実用化が検討されている。図１に、燃料電池の断面構造の模式図の一例を示す。燃料電池１は、電解質膜２０を、燃料極１０と空気極３０との間にサンドイッチして構成されており、燃料極１０の燃料極触媒層１１と、空気極３０の空気極触媒層３１の電極触媒には、通常、白金ナノ粒子が担持された炭素材料が使用される。しかし、燃料極１０の空気極触媒層１１で使用される触媒担体は、酸化と強酸への耐性が高くなければならず、炭素材料では不十分である。また、燃料極触媒層１１の触媒に関する問題点である一酸化炭素被毒には、カーボンブラック・白金複合電極触媒への酸化錫の添加が有効である（非特許文献１）。この酸化錫は、酸化と強酸への耐性が高いため、空気極触媒層３１の触媒担体としても適している。 Currently, the practical application of fuel cells is being studied as an energy source with high energy conversion efficiency considering environmental problems. FIG. 1 shows an example of a schematic diagram of a cross-sectional structure of a fuel cell. The fuel cell 1 includes an electrolyte membrane 20 sandwiched between a fuel electrode 10 and an air electrode 30, and includes a fuel electrode catalyst layer 11 of the fuel electrode 10 and an air electrode catalyst layer 31 of the air electrode 30. For the electrode catalyst, a carbon material on which platinum nanoparticles are supported is usually used. However, the catalyst carrier used in the air electrode catalyst layer 11 of the fuel electrode 10 must have high resistance to oxidation and strong acid, and a carbon material is insufficient. Addition of tin oxide to a carbon black / platinum composite electrode catalyst is effective for carbon monoxide poisoning, which is a problem related to the catalyst of the fuel electrode catalyst layer 11 (Non-patent Document 1). This tin oxide is suitable as a catalyst carrier for the air electrode catalyst layer 31 because of its high resistance to oxidation and strong acid.

　本発明者らは、白金ナノ粒子触媒の担体として、比表面積の大きい酸化錫微粒子の使用を検討したが、凝集が激しく、ハンドリング性が悪かった。次に、公知技術（特許文献１）に基づき、酸化と強酸への耐性が高い酸化チタン粒子の表面上に酸化錫膜を形成したが、酸化錫が一体に連なった平滑な膜状であるので、酸化錫膜の比表面積が小さい。このため、酸化錫膜に担持させた白金ナノ粒子触媒同士が凝集した。一方、従来技術により酸化チタン粒子の表面上に比表面積の大きい酸化錫微粒子層を形成すると、酸化錫微粒子が酸化チタン粒子から剥離した。 The present inventors examined the use of tin oxide fine particles having a large specific surface area as a support for the platinum nanoparticle catalyst, but the aggregation was severe and the handling property was poor. Next, a tin oxide film was formed on the surface of titanium oxide particles having high resistance to oxidation and strong acid based on a known technique (Patent Document 1), but it is a smooth film shape in which tin oxide is integrally linked. The specific surface area of the tin oxide film is small. For this reason, platinum nanoparticle catalysts supported on the tin oxide film were aggregated. On the other hand, when a tin oxide fine particle layer having a large specific surface area was formed on the surface of the titanium oxide particles by the conventional technique, the tin oxide fine particles were separated from the titanium oxide particles.

特開昭６１－２３６６１２号公報Japanese Patent Application Laid-Open No. 61-236612

　本発明は、酸化チタン粉末の表面上に、高密着性および大きい比表面積を備える酸化錫微粒子層が形成された高導電性の導電性複合粒子を提供することを目的とする。 An object of the present invention is to provide highly conductive conductive composite particles in which a tin oxide fine particle layer having high adhesion and a large specific surface area is formed on the surface of a titanium oxide powder.

　本発明者らは、鋭意研究し、従来技術により形成された酸化錫微粒子層が酸化チタン粒子から剥離する原因は、酸化錫微粒子の格子像と酸化チタン粒子表面の格子像とが平行でないからであることを突き止めた。そして、酸化チタン粒子表面に対して平行な酸化チタンの格子像の長さに対して、酸化チタンの格子像に平行な酸化錫の格子像の長さを８０％以上にすることで、酸化錫微粒子の酸化チタン粒子からの剥離を抑制できることを見出した。本発明は、以下に示すいずれかの態様によって上記課題を解決した導電性複合粒子、燃料電池の電極触媒層用組成物、燃料電池の電極触媒層、および燃料電池に関する。 The present inventors have intensively studied and the reason why the tin oxide fine particle layer formed by the conventional technique peels from the titanium oxide particles is that the lattice image of the tin oxide fine particles and the lattice image of the titanium oxide particle surface are not parallel. I found out. Then, by making the length of the lattice image of tin oxide parallel to the lattice image of titanium oxide 80% or more with respect to the length of the lattice image of titanium oxide parallel to the surface of the titanium oxide particles, tin oxide It has been found that separation of fine particles from titanium oxide particles can be suppressed. The present invention relates to conductive composite particles, a composition for an electrode catalyst layer of a fuel cell, an electrode catalyst layer of a fuel cell, and a fuel cell that have solved the above problems by any one of the following aspects.

〔１〕酸化チタン粒子の表面が、多孔質の酸化錫微粒子層で被覆された導電性複合粒子であって、
　高分解能透過型電子顕微鏡像において、前記酸化チタン粒子の表面に平行な酸化チタンの格子像の長さに対して、前記酸化チタンの格子像に平行な酸化錫の格子像の長さが、８０％以上であることを特徴とする、導電性複合粒子。
〔２〕前記酸化チタンがルチル型の結晶構造を含み、前記酸化錫がルチル型の結晶構造を含み、
　前記酸化チタンの前記ルチル型の結晶構造の（１１０）面と、前記酸化錫の前記ルチル型の結晶構造の（１１０）面とが、電子線回折図形において平行である、上記〔１〕記載の導電性複合粒子。
〔３〕上記〔１〕または〔２〕記載の導電性複合粒子と、分散媒とを含有する、燃料電池の電極触媒層用組成物。
〔４〕上記〔１〕または〔２〕記載の導電性複合粒子を含有する、燃料電池の電極触媒層。
〔５〕上記〔４〕記載の燃料電池の電極触媒層を備える、燃料電池。 [1] Conductive composite particles in which the surface of titanium oxide particles is coated with a porous tin oxide fine particle layer,
In the high-resolution transmission electron microscope image, the length of the lattice image of tin oxide parallel to the lattice image of the titanium oxide is 80 with respect to the length of the lattice image of titanium oxide parallel to the surface of the titanium oxide particles. %. Conductive composite particles characterized by being at least%.
[2] The titanium oxide includes a rutile crystal structure, the tin oxide includes a rutile crystal structure,
The (110) plane of the rutile type crystal structure of the titanium oxide and the (110) plane of the rutile type crystal structure of the tin oxide are parallel to each other in the electron diffraction pattern. Conductive composite particles.
[3] A composition for an electrode catalyst layer of a fuel cell, comprising the conductive composite particles according to [1] or [2] above and a dispersion medium.
[4] An electrode catalyst layer for a fuel cell, containing the conductive composite particles according to [1] or [2].
[5] A fuel cell comprising the electrode catalyst layer of the fuel cell according to [4].

　ここで、上記〔１〕の「高分解能透過型電子顕微鏡像において、前記酸化チタン粒子の表面に平行な酸化チタンの格子像」とは、高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子の界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタン粒子の表面と、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の酸化チタンの格子像と、のなす角度の絶対値が１０°以内である格子像である。また、「前記酸化チタンの格子像に平行な酸化錫の格子像」とは、高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子との界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、上述の酸化チタン粒子の表面と平行な、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の酸化チタンの格子像と、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の酸化錫の格子像と、のなす角度の絶対値が１０°以下である格子像である。 Here, in the above [1], “in the high-resolution transmission electron microscope image, the lattice image of titanium oxide parallel to the surface of the titanium oxide particles” refers to the titanium oxide particles in the high-resolution transmission electron microscope image. 4th to 8th layers from the center of the interface of the tin oxide fine particles in the region of width: 50 nm and thickness: 5 nm parallel to the interface, from the surface of the titanium oxide particles and the interface between the titanium oxide particles and the tin oxide fine particles It is a lattice image in which the absolute value of the angle formed by the lattice image of titanium oxide is within 10 °. In addition, “the lattice image of tin oxide parallel to the lattice image of titanium oxide” means a width parallel to the interface from the center of the interface between the titanium oxide particles and the tin oxide particles in the high-resolution transmission electron microscope image. : Within a region of 50 nm and thickness: 5 nm, a lattice image of titanium oxide in the fourth to eighth layers from the interface between the titanium oxide particles and the tin oxide fine particles parallel to the surface of the titanium oxide particles, and the titanium oxide particles And the tin image of the fourth to eighth layers from the interface between the tin oxide fine particles and the tin oxide fine particles are lattice images having an absolute value of 10 ° or less.

　さらに、「高分解能透過型電子顕微鏡像において、前記酸化チタン粒子の表面に平行な酸化チタンの格子像の長さに対して、前記酸化チタンの格子像に平行な酸化錫の格子像の長さが、８０％以上である」とは、以下を意味する。すなわち、高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子との界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の酸化チタンの格子像について、酸化チタン粒子表面に対する角度の絶対値が１０°以下の酸化チタンの格子像の長さ（Ｌｔ）を測定する。また、高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の酸化錫の格子像について、酸化チタンの格子像に対する角度の絶対値が１０°以下の酸化錫の格子像の長さ（Ｌｓ）を測定する。そして、酸化チタンの４層目と酸化錫の４層目、酸化チタンの５層目と酸化錫の５層目のように、各層毎のＬｓとＬｔを用いて各層毎の〔（Ｌｓ／Ｌｔ）×１００〕を算出する。算出した各層ごとの〔（Ｌｓ／Ｌｔ）×１００〕の平均を求め、この平均が８０％以上であることを意味する。 Further, “in the high-resolution transmission electron microscope image, the length of the lattice image of tin oxide parallel to the lattice image of the titanium oxide relative to the length of the lattice image of titanium oxide parallel to the surface of the titanium oxide particles” "Is 80% or more" means the following. That is, in the high-resolution transmission electron microscope image, the titanium oxide particles and the tin oxide fine particles are within the region of the width: 50 nm and the thickness: 5 nm parallel to the interface from the center of the interface between the titanium oxide particles and the tin oxide fine particles. The length (Lt) of the lattice image of titanium oxide having an absolute value of an angle of 10 ° or less with respect to the surface of the titanium oxide particles is measured with respect to the lattice images of the fourth to eighth layers of titanium oxide from the interface. In addition, in the high-resolution transmission electron microscope image, the absolute value of the angle with respect to the lattice image of titanium oxide is 10 ° or less with respect to the lattice image of the fourth to eighth layers from the interface between the titanium oxide particles and the tin oxide fine particles. The length (Ls) of the lattice image of tin oxide is measured. Then, as in the fourth layer of titanium oxide and the fourth layer of tin oxide, the fifth layer of titanium oxide and the fifth layer of tin oxide, the Ls and Lt for each layer are used [[Ls / Lt ) × 100]. The average of [(Ls / Lt) × 100] for each calculated layer is obtained, which means that this average is 80% or more.

　また、上記〔２〕の「前記酸化チタンの前記ルチル型の結晶構造の（１１０）面と、前記酸化錫の前記ルチル型の結晶構造の（１１０）面とが、電子線回折図形において平行である」とは、以下を意味する。すなわち、透過型電子顕微鏡を用いて導電性複合粒子の酸化チタンと酸化錫の双方を視野に入れた電子線回折図形を得る。この電子線回折図形において、ダイレクトスポットを始点に、［１１０］の回折点を通るようにして、ダイレクトスポットから［１１０］方向に数えて１個目および２個目の回折点を通る直線を引く。この直線を［１１０］方向の基準線とする。ここで、酸化チタン由来の回折点と酸化錫由来の回折点とが完全には重ならずにずれて観察された場合、ＴｉＯ_２由来とＳｎＯ_２由来の２つの回折点の中間点を通るように基準線を引く。この基準線からダイレクトスポットを始点に±５°となる境界線を引く。ダイレクトスポットから［１１０］方向に数えて３個目および４個目の回折点が、２本の境界線の内側（基準線側）に存在することを意味する。ここで、［１１０］方向は、（１１０）面に垂直であるので、酸化チタンのルチル型の結晶構造の［１１０］方向と、酸化錫のルチル型の結晶構造の［１１０］方向とが、電子線回折図形上で平行であることと、酸化チタンのルチル型の結晶構造の（１１０）面と、酸化錫のルチル型の結晶構造の（１１０）面とが、電子線回折図形上で平行であることは、等価である。 In the above [2], the (110) plane of the rutile crystal structure of the titanium oxide and the (110) plane of the rutile crystal structure of the tin oxide are parallel in the electron diffraction pattern. “Yes” means the following. That is, an electron diffraction pattern with both the titanium oxide and the tin oxide of the conductive composite particles in view is obtained using a transmission electron microscope. In this electron beam diffraction pattern, starting from the direct spot and passing through the [110] diffraction point, straight lines passing through the first and second diffraction points are drawn from the direct spot in the [110] direction. . This straight line is taken as a reference line in the [110] direction. Here, if a diffraction point derived from the titanium oxide and the diffraction point derived from the tin oxide observed displaced without completely overlap, so as to pass through the midpoint of the two diffraction points from the SnO ₂ derived TiO ₂ Draw a reference line. From this reference line, a boundary line of ± 5 ° is drawn starting from the direct spot. It means that the third and fourth diffraction points counted in the [110] direction from the direct spot are present inside the two boundary lines (on the reference line side). Here, since the [110] direction is perpendicular to the (110) plane, the [110] direction of the rutile crystal structure of titanium oxide and the [110] direction of the rutile crystal structure of tin oxide are: It is parallel on the electron diffraction pattern, and the (110) plane of the rutile crystal structure of titanium oxide and the (110) plane of the rutile crystal structure of tin oxide are parallel on the electron diffraction pattern. Is equivalent.

　本発明の上記〔１〕の導電性複合粒子によれば、高分解能透過型電子顕微鏡像において、酸化チタン粒子表面に平行な酸化チタンの格子像の長さに対して、酸化チタンの格子像に平行な酸化錫の格子像の長さが、８０％以上であるため、酸化錫微粒子層と酸化チタン粒子の密着性が高い。また、酸化チタン粒子上に、多孔質の酸化錫微粒子層が形成されるため、上記〔１〕の導電性複合粒子は比表面積が大きく、かつ高導電性である。上記〔２〕によれば、酸化チタンのルチル型の結晶構造の（１１０）面と、酸化錫のルチル型の結晶構造の（１１０）面とが電子線回折図形上で平行な導電性複合粒子が得られる。上記〔３〕によれば、白金ナノ粒子触媒の担体として適している上記〔１〕または〔２〕の導電性複合粒子を含有する燃料電池の電極触媒層を、容易に形成可能な組成物を提供することができる。上記〔４〕によれば、この燃料電池の電極触媒層に含有される上記〔１〕または〔２〕の導電性複合粒子は、酸化錫微粒子層と酸化チタン粒子との密着性が高く、比表面積が大きく、かつ導電性が高いので、信頼性の高い燃料電池の電極触媒層を提供することができる。上記〔５〕によれば、上記〔４〕の燃料電池の電極触媒層を備える高信頼性の燃料電池を提供することが可能である。 According to the conductive composite particle [1] of the present invention, in the high-resolution transmission electron microscope image, the lattice image of titanium oxide is longer than the length of the lattice image of titanium oxide parallel to the titanium oxide particle surface. Since the length of the parallel lattice image of tin oxide is 80% or more, the adhesion between the tin oxide fine particle layer and the titanium oxide particles is high. Further, since the porous tin oxide fine particle layer is formed on the titanium oxide particles, the conductive composite particles of [1] have a large specific surface area and high conductivity. According to the above [2], the conductive composite particles in which the (110) plane of the rutile crystal structure of titanium oxide and the (110) plane of the rutile crystal structure of tin oxide are parallel on the electron diffraction pattern Is obtained. According to said [3], the composition which can form easily the electrode catalyst layer of the fuel cell containing the electroconductive composite particle of said [1] or [2] suitable as a support | carrier of a platinum nanoparticle catalyst. Can be provided. According to the above [4], the conductive composite particles of [1] or [2] contained in the electrode catalyst layer of the fuel cell have high adhesion between the tin oxide fine particle layer and the titanium oxide particles, Since the surface area is large and the conductivity is high, a highly reliable electrode catalyst layer for a fuel cell can be provided. According to said [5], it is possible to provide a highly reliable fuel cell provided with the electrode catalyst layer of the fuel cell of said [4].

燃料電池の断面構造の一例を模式的に示す断面図である。It is sectional drawing which shows typically an example of the cross-section of a fuel cell. 実施例１で作製した導電性複合粒子の走査型電子顕微鏡写真である。2 is a scanning electron micrograph of conductive composite particles produced in Example 1. FIG. 実施例１で作製した導電性複合粒子の透過型電子顕微鏡写真である。2 is a transmission electron micrograph of conductive composite particles produced in Example 1. FIG. 実施例１で作製した導電性複合粒子の透過型電子顕微鏡付属のエネルギー分散型Ｘ線分光分析装置によるＴｉマッピングである。It is Ti mapping by the energy dispersive X-ray-spectral-analysis apparatus attached to the transmission electron microscope of the electroconductive composite particle produced in Example 1. FIG. 実施例１で作製した導電性複合粒子の透過型電子顕微鏡付属のエネルギー分散型Ｘ線分光分析装置によるＳｎマッピングである。It is Sn mapping by the energy dispersive X-ray-spectral-analysis apparatus attached to the transmission electron microscope of the electroconductive composite particle produced in Example 1. FIG. 実施例１で作製した導電性複合粒子の透過型電子顕微鏡写真である。2 is a transmission electron micrograph of conductive composite particles produced in Example 1. FIG. 実施例１で作製した導電性複合粒子の高分解能透過型電子顕微鏡像である。2 is a high-resolution transmission electron microscope image of conductive composite particles produced in Example 1. FIG. 比較例１で作製した導電性複合粒子の高分解能透過型電子顕微鏡像である。3 is a high-resolution transmission electron microscope image of conductive composite particles produced in Comparative Example 1. FIG. 実施例１で作製した導電性複合粒子の高分解能透過型電子顕微鏡像である。2 is a high-resolution transmission electron microscope image of conductive composite particles produced in Example 1. FIG. 実施例１で作製した導電性複合粒子の透過型電子顕微鏡写真と電子線回折図形である。It is the transmission electron micrograph and electron diffraction pattern of the electroconductive composite particle produced in Example 1. FIG. 実施例１で作製した導電性複合粒子の電子線回折図形である。2 is an electron diffraction pattern of conductive composite particles produced in Example 1. FIG. 実施例１で作製した導電性複合粒子の電子線回折図形と解析結果である。It is the electron-beam diffraction pattern and analysis result of the electroconductive composite particle produced in Example 1. FIG. 実施例２で作製した導電性複合粒子の高分解能透過型電子顕微鏡像である。3 is a high-resolution transmission electron microscope image of conductive composite particles produced in Example 2. FIG. 実施例２で作製した導電性複合粒子の透過型電子顕微鏡写真と電子線回折図形である。It is the transmission electron micrograph and electron diffraction pattern of the electroconductive composite particle produced in Example 2. FIG. 実施例２で作製した導電性複合粒子の電子線回折図形である。3 is an electron diffraction pattern of conductive composite particles produced in Example 2. FIG. 実施例２で作製した導電性複合粒子の電子線回折図形と解析結果である。It is the electron-beam diffraction pattern and analysis result of the electroconductive composite particle produced in Example 2. FIG. 実施例３で作製した導電性複合粒子の高分解能透過型電子顕微鏡像である。4 is a high-resolution transmission electron microscope image of conductive composite particles produced in Example 3. FIG. 実施例３で作製した導電性複合粒子の透過型電子顕微鏡写真と電子線回折図形である。It is a transmission electron micrograph and electron beam diffraction pattern of the electroconductive composite particle produced in Example 3. 実施例３で作製した導電性複合粒子の電子線回折図形である。4 is an electron diffraction pattern of conductive composite particles produced in Example 3. FIG. 実施例３で作製した導電性複合粒子の電子線回折図形と解析結果である。It is an electron beam diffraction pattern and analysis result of the electroconductive composite particle produced in Example 3. FIG. （Ｌｓ／Ｌｔ）×１００〕を求めるために測定する箇所を説明するための模式図である。It is a schematic diagram for demonstrating the location measured in order to obtain | require (Ls / Lt) * 100]. 酸化チタンのルチル型の結晶構造の（１１０）面と、酸化錫のルチル型の結晶構造の（１１０）面とが、電子線回折図形で平行であることを説明するための図である。It is a figure for demonstrating that the (110) plane of a rutile type crystal structure of a titanium oxide and the (110) plane of a rutile type crystal structure of a tin oxide are parallel by an electron beam diffraction pattern.

　以下、本発明を実施形態に基づいて具体的に説明する。なお、％は特に明記しない限り、単に百分率を示す場合を除いて、質量％を意味する。 Hereinafter, the present invention will be specifically described based on embodiments. In addition, unless otherwise indicated,% means the mass% except the case where only a percentage is shown.

〔導電性複合粒子〕
　本実施形態の導電性複合粒子は、酸化チタン粒子の表面が、多孔質の酸化錫微粒子層で被覆された導電性複合粒子であって、その高分解能透過型電子顕微鏡像において、酸化チタン粒子の表面に平行な酸化チタンの格子像の長さに対して、上記酸化チタンの格子像に平行な酸化錫の格子像の長さが、８０％以上であることを特徴とする。 [Conductive composite particles]
The conductive composite particle of the present embodiment is a conductive composite particle in which the surface of the titanium oxide particle is coated with a porous tin oxide fine particle layer, and in the high-resolution transmission electron microscope image, The length of the lattice image of tin oxide parallel to the lattice image of the titanium oxide is 80% or more with respect to the length of the lattice image of titanium oxide parallel to the surface.

　次に、本実施形態の導電性複合粒子の製造方法の一例を説明する。この一例では、酸化錫として、Ｓｂドープ酸化錫を使用する。まず、酸化チタン粒子：３０ｇに対し、０．０５～０．２Ｍの塩酸、硝酸または硫酸等の酸で、４０～６０℃で、３０～２時間酸洗浄を行い、続いて水洗を行う。この酸洗浄で、０．０５Ｍ未満の酸を使用すると、本実施形態の導電性複合粒子は得られない。次に、この酸化チタン粒子：３０ｇを、水：８００ｇに加え、温度：２０～９０℃で撹拌しながら加熱保持し、酸化チタン粒子を均一に分散させ、酸化チタン粒子含有分散液を調製する。この酸化チタン粒子含有分散液に、酸化チタン：１００質量部に対して、ＳｎＣｌ_４：５０～２００質量部、ＳｂＣｌ_３：２～２５質量部を溶解した塩化錫水溶液を加え、１０～３５ｗｔ％の水酸化ナトリウム水溶液を、２０～８０℃、ｐＨ３～９の範囲に維時しつつ、３分～２時間かけて注入し、酸化チタン粒子表面に、Ｓｂ含有水酸化錫からなる被覆層を析出させる。次に、Ｓｂ含有水酸化錫からなる被覆層を表面に析出させた酸化チタン粒子を濾別し、得られた酸化チタン粒子を洗浄した後、空気中、５００～１０００℃で１～２時間保持することにより、導電性複合粒子を得ることができる。ここで、上記の方法では、酸化チタン粒子含有分散液に塩化錫水溶液を加えた後に水酸化ナトリウム水溶液を注入しているが、酸化チタン粒子含有分散液に塩化錫水溶液と同時に水酸化ナトリウム水溶液を注入しても良い。 Next, an example of the manufacturing method of the electroconductive composite particle of this embodiment is demonstrated. In this example, Sb-doped tin oxide is used as tin oxide. First, 30 g of titanium oxide particles are acid-washed with 0.05 to 0.2 M acid such as hydrochloric acid, nitric acid or sulfuric acid at 40 to 60 ° C. for 30 to 2 hours, followed by washing with water. If an acid of less than 0.05M is used in this acid cleaning, the conductive composite particles of this embodiment cannot be obtained. Next, 30 g of the titanium oxide particles are added to 800 g of water and heated and held at a temperature of 20 to 90 ° C. while stirring to disperse the titanium oxide particles uniformly, thereby preparing a dispersion containing titanium oxide particles. To this titanium oxide particle-containing dispersion, an aqueous tin chloride solution in which SnCl ₄ : 50 to 200 parts by mass and SbCl ₃ : 2 to 25 parts by mass is added to 100 parts by mass of titanium oxide, and 10 to 35 wt% An aqueous solution of sodium hydroxide is injected over 3 minutes to 2 hours while maintaining a pH of 3 to 9 at 20 to 80 ° C., and a coating layer made of Sb-containing tin hydroxide is deposited on the surface of the titanium oxide particles. . Next, the titanium oxide particles having a coating layer made of Sb-containing tin hydroxide deposited on the surface are filtered off, and the obtained titanium oxide particles are washed and then kept in air at 500 to 1000 ° C. for 1 to 2 hours. By doing so, conductive composite particles can be obtained. Here, in the above method, the aqueous solution of tin chloride is added to the dispersion containing titanium oxide particles, and then the aqueous solution of sodium hydroxide is injected. It may be injected.

　なお、第一の公知技術では、酸化チタン粒子を酸洗浄せずに、酸化チタン粒子含有分散液を調製してから、酸化チタン粒子の表面にＳｂ含有水酸化錫からなる被覆層を析出させた後、高温で保持することにより導電性複合粒子を作製していた。また、第二の公知技術として、シランカップリング剤を添加した酸化チタン粒子含有分散液を使用する点で第一の公知技術と異なる導電性複合粒子の作製方法もあった。上述の本実施形態に係る導電性複合粒子の製造方法は、酸洗浄された酸化チタン粒子を用いる点で、第一及び第二の公知技術と異なっている。 In the first known technique, a titanium oxide particle-containing dispersion was prepared without acid cleaning the titanium oxide particles, and then a coating layer made of Sb-containing tin hydroxide was deposited on the surface of the titanium oxide particles. Thereafter, conductive composite particles were produced by holding at a high temperature. In addition, as a second known technique, there is a method for producing conductive composite particles that is different from the first known technique in that a dispersion containing titanium oxide particles to which a silane coupling agent is added is used. The method for producing conductive composite particles according to this embodiment described above is different from the first and second known techniques in that acid-washed titanium oxide particles are used.

　図２に、上述の本実施形態に係る導電性複合粒子の製造方法により形成された後述する実施例１の導電性複合粒子の走査型電子顕微鏡写真を示す。また、実施例１で作製した導電性複合粒子４について、図３に透過型電子顕微鏡写真を、図４に透過型電子顕微鏡付属のエネルギー分散型Ｘ線分光分析装置（ＥＤＳ）によるＴｉマッピングを、図５に同装置によるＳｎマッピングを示す。図２から、導電性複合粒子４の表面に微細粒子が存在することがわかる。図３から、微細粒子が、層状で、導電性複合粒子４の表面に存在することがわかる。さらに、図４および図５から、酸化チタン粒子５の表面に、酸化錫微粒子層６が存在することを確認することができる。 FIG. 2 shows a scanning electron micrograph of conductive composite particles of Example 1 described later formed by the above-described method for manufacturing conductive composite particles according to the present embodiment. Moreover, about the electroconductive composite particle 4 produced in Example 1, FIG. 3 shows a transmission electron microscope photograph, and FIG. 4 shows Ti mapping by an energy dispersive X-ray spectrometer (EDS) attached to the transmission electron microscope. FIG. 5 shows Sn mapping by the same apparatus. FIG. 2 shows that fine particles are present on the surface of the conductive composite particles 4. From FIG. 3, it can be seen that the fine particles are layered and exist on the surface of the conductive composite particles 4. Furthermore, it can be confirmed from FIGS. 4 and 5 that the tin oxide fine particle layer 6 exists on the surface of the titanium oxide particles 5.

　次に、図６に、実施例１で作製した導電性複合粒子４の透過型電子顕微鏡写真を、図７に、酸化チタン粒子５と酸化錫微粒子６との界面部を拡大した高分解能透過型電子顕微鏡像を示す。図７から、高分解能透過型電子顕微鏡像において、酸化チタン粒子５の表面に対して平行な酸化チタンの格子像と、酸化錫の格子像とが平行であることがわかる。参考として、図８に、後述する比較例１で作製した導電性複合粒子４の酸化チタン粒子５と酸化錫微粒子６との界面部を拡大した高分解能透過型電子顕微鏡像を示す。図８から、比較例１で作製した導電性複合粒子４は、高分解能透過型電子顕微鏡像において、酸化チタン粒子５の表面に対して平行な酸化チタンの格子像と、酸化錫の格子像とが、平行ではないことがわかる。 Next, FIG. 6 shows a transmission electron micrograph of the conductive composite particles 4 produced in Example 1, and FIG. 7 shows a high-resolution transmission type in which the interface between the titanium oxide particles 5 and the tin oxide particles 6 is enlarged. An electron microscope image is shown. FIG. 7 shows that in the high-resolution transmission electron microscope image, the lattice image of titanium oxide parallel to the surface of the titanium oxide particles 5 and the lattice image of tin oxide are parallel. For reference, FIG. 8 shows a high-resolution transmission electron microscope image in which the interface between the titanium oxide particles 5 and the tin oxide fine particles 6 of the conductive composite particles 4 produced in Comparative Example 1 described later is enlarged. From FIG. 8, the conductive composite particle 4 produced in Comparative Example 1 shows a lattice image of titanium oxide parallel to the surface of the titanium oxide particle 5 and a lattice image of tin oxide in a high-resolution transmission electron microscope image. However, it turns out that it is not parallel.

　本実施形態の導電性複合粒子（以下、導電性複合粒子という）では、その高分解能透過型電子顕微鏡像において、酸化チタン粒子の表面に平行な酸化チタンの格子像の長さに対して、上記酸化チタンの格子像に平行な酸化錫の格子像の長さが、８０％以上である。酸化チタンの格子像に平行な酸化錫の格子像の長さが、８０％未満では、酸化チタン粒子と酸化錫微粒子層の密着性が低下する。 In the conductive composite particles of the present embodiment (hereinafter referred to as conductive composite particles), in the high-resolution transmission electron microscope image, the length of the lattice image of titanium oxide parallel to the surface of the titanium oxide particles is The length of the tin oxide lattice image parallel to the titanium oxide lattice image is 80% or more. If the length of the tin oxide lattice image parallel to the lattice image of titanium oxide is less than 80%, the adhesion between the titanium oxide particles and the tin oxide fine particle layer decreases.

　また、導電性複合粒子において、酸化チタンがルチル型の結晶構造を含み、酸化錫がルチル型の結晶構造を含む、すなわち、酸化チタンがルチル型の結晶構造を有する相が主相であり、酸化錫がルチル型の結晶構造を有する相が主相であることが好ましい。より具体的には、酸化チタン粒子におけるルチル型の結晶構造を有する相の質量率を７５～１００％としても良く、酸化錫微粒子層をルチル型の結晶構造を有する相のみで構成しても良い。例えば、ルチル型の結晶構造を有する安定相と、アナターゼ型の結晶構造を有する準安定相と、の混合相で酸化チタン粒子が構成されていても良い。
　そして、電子線回折図形において、酸化チタンのルチル型の結晶構造の（１１０）面と、酸化錫のルチル型の結晶構造の（１１０）面とが、平行であることが好ましい。この場合、酸化チタンの結晶面（結晶格子）と酸化錫の結晶面（結晶格子）のミスマッチが小さい。ここで、酸化チタンの結晶構造がルチル型であり、酸化錫の結晶構造がルチル型であることは、Ｘ線回折法により確認する。 In the conductive composite particles, the titanium oxide has a rutile crystal structure and the tin oxide has a rutile crystal structure, that is, the phase in which the titanium oxide has a rutile crystal structure is the main phase. The phase in which tin has a rutile crystal structure is preferably the main phase. More specifically, the mass ratio of the phase having a rutile type crystal structure in the titanium oxide particles may be 75 to 100%, and the tin oxide fine particle layer may be composed only of the phase having a rutile type crystal structure. . For example, titanium oxide particles may be composed of a mixed phase of a stable phase having a rutile crystal structure and a metastable phase having an anatase crystal structure.
In the electron diffraction pattern, the (110) plane of the rutile crystal structure of titanium oxide and the (110) plane of the rutile crystal structure of tin oxide are preferably parallel. In this case, the mismatch between the crystal plane (crystal lattice) of titanium oxide and the crystal plane (crystal lattice) of tin oxide is small. Here, it is confirmed by an X-ray diffraction method that the crystal structure of titanium oxide is rutile and the crystal structure of tin oxide is rutile.

　図１０に、実施例１で作製した導電性複合粒子４の透過型電子顕微鏡写真と電子線回折図形を示す。左上の透過型電子顕微鏡写真の白の破線Ａで囲んだ部分の電子線回折図形を、右上（ＴｉＯ_２／ＳｎＯ_２）に示す。左上の透過型電子顕微鏡写真の白の破線Ａ中の黒点Ｂで示す酸化チタンの電子線回折図形を、左下（ＴｉＯ_２）に示す。左上の透過型電子顕微鏡写真の白の破線Ａ中の白点Ｃで示す酸化錫の電子線回折図形を、右下（ＳｎＯ_２）に示す。 FIG. 10 shows a transmission electron micrograph and an electron beam diffraction pattern of the conductive composite particles 4 produced in Example 1. The electron diffraction pattern of the portion surrounded by the white broken line A in the upper left transmission electron micrograph is shown in the upper right (TiO ₂ / SnO ₂ ). An electron diffraction pattern of titanium oxide indicated by a black dot B in a white broken line A in the upper left transmission electron micrograph is shown in the lower left (TiO ₂ ). An electron diffraction pattern of tin oxide indicated by a white dot C in a white broken line A in the upper left transmission electron micrograph is shown in the lower right (SnO ₂ ).

　次に、図１１に、実施例１で作製した導電性複合粒子４の電子線回折図形を示す。図１１の左上、左下、右下の電子線回折図形は、それぞれ図１０の右上、左下、右下の電子線回折図形と同じである。また図１１の右上に、酸化チタンの電子線回折図形（左下）と酸化錫の電子線回折図形（右下）とを重ね合わせた結果を示す。この右上の図からわかるように、酸化チタンの電子線回折図形と酸化錫の電子線回折図形には、ほとんどズレがない。 Next, FIG. 11 shows an electron diffraction pattern of the conductive composite particles 4 produced in Example 1. FIG. The electron diffraction patterns at the upper left, lower left, and lower right in FIG. 11 are the same as the electron diffraction patterns at the upper right, lower left, and lower right in FIG. 10, respectively. Further, the result of superposing the electron diffraction pattern of titanium oxide (lower left) and the electron diffraction pattern of tin oxide (lower right) is shown in the upper right of FIG. As can be seen from the upper right figure, there is almost no deviation between the electron diffraction pattern of titanium oxide and the electron diffraction pattern of tin oxide.

　図１２に、実施例１で作製した導電性複合粒子４の電子線回折図形と解析結果を示す。図１２の左上での酸化チタンの（１１０）面による回折パターン位置と、図１２の右上での酸化錫の（１１０）面による回折パターン位置にズレがない。後述するように、図２２での解析の結果、酸化チタンのルチル型の結晶構造の（１１０）面と、酸化錫のルチル型の結晶構造の（１１０）面とが、電子線回折図形上で平行であることがわかる。このため、図１２の下段に、酸化チタンの（１１０）面と酸化錫の（１１０）面が電子線回折図形上で平行であると記載する。同様の解析から、酸化チタンの（１１２）面と酸化錫の（１１２）面が電子線回折図形上で平行であり、紙面（写真）に対して垂直な方向である酸化チタンの（１１１）面と酸化錫の（１１１）面が電子線回折図形上で平行であることがわかる。そして、図１２の下段にこれらの解析の結果を記載した。ここで、図１２中の「ＴＤ」は、酸化チタンと酸化錫との界面に平行な方向を表し、「ＲＤ」は、酸化チタンと酸化錫との界面に垂直な方向を表し、「ＮＤ」は、紙面（写真）に対して垂直な方向を表す。また、図１６に、実施例２で作製した導電性複合粒子の電子線回折図形と解析結果を示し、図２０に、実施例３で作製した導電性複合粒子の電子線回折図形と解析結果を示す。 FIG. 12 shows an electron beam diffraction pattern and analysis results of the conductive composite particles 4 produced in Example 1. There is no deviation between the diffraction pattern position due to the (110) plane of titanium oxide in the upper left of FIG. 12 and the diffraction pattern position due to the (110) plane of tin oxide in the upper right of FIG. As will be described later, as a result of the analysis in FIG. 22, the (110) plane of the rutile crystal structure of titanium oxide and the (110) plane of the rutile crystal structure of tin oxide are shown on the electron diffraction pattern. It turns out that it is parallel. For this reason, the lower part of FIG. 12 describes that the (110) plane of titanium oxide and the (110) plane of tin oxide are parallel on the electron diffraction pattern. From the same analysis, the (112) surface of titanium oxide and the (112) surface of tin oxide are parallel to each other on the electron diffraction pattern, and the (111) surface of titanium oxide is perpendicular to the paper surface (photograph). It can be seen that the (111) plane of tin oxide is parallel on the electron diffraction pattern. The results of these analyzes are shown in the lower part of FIG. Here, “TD” in FIG. 12 represents a direction parallel to the interface between titanium oxide and tin oxide, “RD” represents a direction perpendicular to the interface between titanium oxide and tin oxide, and “ND”. Represents a direction perpendicular to the page (photo). FIG. 16 shows the electron diffraction pattern and analysis results of the conductive composite particles prepared in Example 2, and FIG. 20 shows the electron diffraction pattern and analysis results of the conductive composite particles prepared in Example 3. Show.

　図１２、図１６、図２０のいずれの解析結果においても、酸化チタンの（１１０）面と酸化錫の（１１０）面とは、電子線回折図形上で平行である。なお、図７～図２０は（１１０）面に対応する回折点が観察されるように電子線の入射方位を調整して観察を行っている。このため、いずれの図においても酸化チタンの（１１０）面と酸化錫の（１１０）面とが電子線回折図形において平行になっていることが観察される。このように、電子線回折図形において、酸化チタンのルチル型の結晶構造の（１１０）面と、酸化錫のルチル型の結晶構造の（１１０）面とが平行であることが好ましい。この場合、酸化チタンの結晶面（結晶格子）と酸化錫の結晶面（結晶格子）とのミスマッチが小さい。 12, 16, and 20, the (110) plane of titanium oxide and the (110) plane of tin oxide are parallel on the electron diffraction pattern. 7 to 20, the observation is performed by adjusting the incident direction of the electron beam so that the diffraction point corresponding to the (110) plane is observed. For this reason, in any figure, it is observed that the (110) plane of titanium oxide and the (110) plane of tin oxide are parallel in the electron beam diffraction pattern. Thus, in the electron diffraction pattern, the (110) plane of the rutile crystal structure of titanium oxide and the (110) plane of the rutile crystal structure of tin oxide are preferably parallel. In this case, the mismatch between the crystal plane (crystal lattice) of titanium oxide and the crystal plane (crystal lattice) of tin oxide is small.

　本実施形態の導電性複合粒子の製造に用いられる酸化チタン粒子の比表面積は、１～１０ｍ^２／ｇであると、好ましい。１ｍ^２／ｇ未満では、導電性複合粒子の比表面積を大きくしにくい。１０ｍ^２／ｇを超えると、酸化チタン粒子の凝集力が大きくなるので、上述の製造工程において、酸化チタン粒子含有分散液中に酸化チタン粒子を均一に分散させにくくなる。 The specific surface area of the titanium oxide particles used for producing the conductive composite particles of the present embodiment is preferably 1 to 10 m ² / g. If it is less than 1 m ² / g, it is difficult to increase the specific surface area of the conductive composite particles. If it exceeds 10 m ² / g, the cohesive force of the titanium oxide particles becomes large, so that it becomes difficult to uniformly disperse the titanium oxide particles in the titanium oxide particle-containing dispersion in the above-described production process.

　酸化チタンの結晶形は、特に限定されるわけではないが、ルチル型が好ましい。アナターゼ型やブルッカイト型では、酸化チタンの表面に酸化錫微粒子の前駆体を、共沈法等により析出、または形成し難いので工夫が必要である。 The crystal form of titanium oxide is not particularly limited, but is preferably a rutile type. In the anatase type and brookite type, it is difficult to deposit or form a tin oxide fine particle precursor on the surface of titanium oxide by a coprecipitation method or the like.

　酸化錫微粒子層は多孔質である。これにより、酸化チタン粒子に導電性を付与し、また、白金ナノ粒子を担持させることができる。さらに、高分解能透過型電子顕微鏡像において、酸化チタン粒子の表面と接触する酸化錫の格子像が、酸化チタン粒子の表面の格子像に対して平行であることから、酸化錫微粒子層と酸化チタン粒子の密着性が高い。ここで、酸化錫は、その一部がＳｎＯ_２－δ（式中、δは０～０．５である）の構造に還元されていると、導電性の点から、好ましい。また、酸化錫は、Ｓｂ、Ｐ、Ｆ、Ｃｌ等でドープされていることがより好ましい。この場合、還元されている酸化錫の導電性等を安定化させることができる。 The tin oxide fine particle layer is porous. Thereby, electroconductivity can be provided to the titanium oxide particles, and platinum nanoparticles can be supported. Further, in the high-resolution transmission electron microscope image, since the lattice image of tin oxide in contact with the surface of the titanium oxide particles is parallel to the lattice image of the surface of the titanium oxide particles, the tin oxide fine particle layer and the titanium oxide layer High adhesion of particles. Here, it is preferable from the viewpoint of conductivity that a part of tin oxide is reduced to a structure of SnO _2-δ (where δ is 0 to 0.5). The tin oxide is more preferably doped with Sb, P, F, Cl or the like. In this case, the conductivity and the like of the reduced tin oxide can be stabilized.

　酸化錫がＳｂでドープされる場合には、導電性の観点から、ＳｎＯ_２とＳｂの合計：１００質量部に対して、酸化錫が、０質量部より多く１５質量部以下のＳｂを含むことが好ましい。Ｓｂが１５重量部より多いと、不純物が析出することにより酸化錫微粒子層が酸化チタン粒子から剥離しやすくなる、白金触媒が担持されにくくなるなどの問題がある。ここで、定量分析は、ＳｎとＳｂについて、ＩＣＰ（誘導結合プラズマ）法で行い、ＳｎはすべてＳｎＯ_２であり、ＳｂはすべてＳｂであるものとして、計算する。なお、この定量分析では、Ｓｎイオン濃度が１～１００ｐｐｍとなるように酸化錫を過酸化ソーダに溶解した後、酸性に戻したものを測定試料とする。 If the tin oxide is doped with Sb, from the viewpoint of conductivity, total SnO ₂ and Sb: per 100 parts by weight, tin oxide, include many 15 parts by mass or less of Sb from 0 parts by weight Is preferred. When Sb is more than 15 parts by weight, there are problems that impurities are precipitated and the tin oxide fine particle layer is easily separated from the titanium oxide particles, and the platinum catalyst is hardly supported. Here, the quantitative analysis is performed for Sn and Sb by the ICP (inductively coupled plasma) method, assuming that all Sn is SnO ₂ and all Sb is Sb. In this quantitative analysis, a measurement sample is prepared by dissolving tin oxide in sodium peroxide so that the Sn ion concentration becomes 1 to 100 ppm and then returning it to acidity.

　酸化錫微粒子層を構成する酸化錫微粒子の平均粒径は、３～２０ｎｍであると好ましい。ここで、酸化錫微粒子の平均粒径は、ＴＥＭによる観察結果から算出する。 The average particle diameter of the tin oxide fine particles constituting the tin oxide fine particle layer is preferably 3 to 20 nm. Here, the average particle diameter of the tin oxide fine particles is calculated from the observation result by TEM.

　酸化錫微粒子層は、０．００５～０．０７μｍの厚さであると好ましい。この場合、比表面積が大きくなることにより白金ナノ粒子の担持量が増加し、酸化チタン粒子への導電性を付与できる。ここで、酸化錫微粒子層の厚さは、ＴＥＭによる観察結果から算出する。なお、ＴＥＭ観察では、導電性複合粒子を練り込んだエポキシ樹脂から、機械研磨及びイオン研磨（Ｉｏｎ　Ｐｏｌｉｓｈｉｎｇ（ＩＰ）法またはＣｒｏｓｓ－ｓｅｃｔｉｏｎ　Ｐｏｌｉｓｈｉｎｇ（ＣＰ）法）により薄片を作成し、電子線が透過する厚さとなった領域について観察を行う。例えば、５０個程度の導電性複合粒子の粒子径を測定して、その平均値から平均粒径を求めることができる。また、例えば、５個の導電性複合粒子について酸化錫微粒子層の厚さを測定して、その平均値から酸化錫微粒子層の厚さを求めることができる。ここで、測定する導電性複合粒子の数はこれに限定されず、観察視野の倍率等によって決定しても良い。 The tin oxide fine particle layer preferably has a thickness of 0.005 to 0.07 μm. In this case, when the specific surface area increases, the amount of platinum nanoparticles supported increases, and conductivity to the titanium oxide particles can be imparted. Here, the thickness of the tin oxide fine particle layer is calculated from the observation result by TEM. In TEM observation, a thin piece is prepared from an epoxy resin kneaded with conductive composite particles by mechanical polishing and ion polishing (Ion Polishing (IP) method or Cross-section Polishing (CP) method), and an electron beam is transmitted. Observe the region where the thickness is increased. For example, the particle diameter of about 50 conductive composite particles can be measured, and the average particle diameter can be obtained from the average value. For example, the thickness of the tin oxide fine particle layer can be measured for five conductive composite particles, and the thickness of the tin oxide fine particle layer can be obtained from the average value. Here, the number of conductive composite particles to be measured is not limited to this, and may be determined according to the magnification of the observation field.

　酸化錫微粒子層は、導電性複合粒子：１００質量部に対して、２０～７０質量部であると、比表面積、導電性の観点から好ましい。 The tin oxide fine particle layer is preferably 20 to 70 parts by mass with respect to 100 parts by mass of the conductive composite particles from the viewpoint of specific surface area and conductivity.

　導電性複合粒子のＢＥＴ比表面積は、酸化チタン粒子のＢＥＴ比表面積の２～５０倍であると、比表面積が大きくなることによる白金ナノ粒子の担持量の増加の観点から好ましい。 The BET specific surface area of the conductive composite particles is preferably 2 to 50 times the BET specific surface area of the titanium oxide particles from the viewpoint of an increase in the amount of platinum nanoparticles supported due to an increase in the specific surface area.

　導電性複合粒子の圧粉体抵抗率は、１００００Ω・ｃｍ未満であると好ましく、１０Ω・ｃｍ未満であると、より好ましい。 The green compact resistivity of the conductive composite particles is preferably less than 10,000 Ω · cm, and more preferably less than 10 Ω · cm.

　以上のような本実施形態に係る導電性複合粒子は、酸化チタン粒子表面と酸化錫微粒子層との密着性が高く、例えば、電極触媒層用組成物作製時にメカニカルアロイングを使用しても、機械的衝撃に耐えることができる。 The conductive composite particles according to the present embodiment as described above have high adhesion between the titanium oxide particle surface and the tin oxide fine particle layer, for example, even when mechanical alloying is used at the time of preparing the composition for the electrode catalyst layer, Can withstand mechanical shock.

〔燃料電池の電極触媒層用組成物〕
　本実施形態の燃料電池の電極触媒層用組成物（以下、電極触媒層用組成物という）は、上記導電性複合粒子と、分散媒とを含有する。電極触媒層とは、例えば、図１に示されるような燃料極触媒層１１および空気極触媒層３１からなる群より選択される少なくとも１種の触媒層である。導電性複合粒子に白金ナノ粒子を担持させる方法としては、電極触媒層用組成物中の導電性複合粒子に白金ナノ粒子を担持させても良いが、作業性の観点から、予め導電性複合粒子に白金ナノ粒子を担持させた後、電極触媒層用組成物とする方が好ましい。ここで、導電性複合粒子に白金ナノ粒子を担持させる方法は、導電性複合粒子を分散させた溶液中に、溶液を撹拌しながら白金ナノ粒子分散液を添加した後、得られた液体を乾燥する等の公知の方法でよい。 [Composition for electrode catalyst layer of fuel cell]
The composition for an electrode catalyst layer of the fuel cell of the present embodiment (hereinafter referred to as an electrode catalyst layer composition) contains the conductive composite particles and a dispersion medium. The electrode catalyst layer is, for example, at least one catalyst layer selected from the group consisting of the fuel electrode catalyst layer 11 and the air electrode catalyst layer 31 as shown in FIG. As a method for supporting platinum nanoparticles on the conductive composite particles, platinum nanoparticles may be supported on the conductive composite particles in the composition for the electrode catalyst layer. After the platinum nanoparticles are supported on the electrode catalyst layer, the electrode catalyst layer composition is preferred. Here, the method of supporting the platinum nanoparticles on the conductive composite particles is to add the platinum nanoparticle dispersion while stirring the solution in the solution in which the conductive composite particles are dispersed, and then dry the obtained liquid. It may be a known method such as.

　分散媒は、導電性複合粒子を分散させ、かつ電極触媒層用組成物の成膜性を向上させる。分散媒としては、水、アルコール類が好ましい。アルコール類としては、メタノール、エタノール等が挙げられる。分散媒の含有量は、電極触媒層用組成物：１００質量部に対して、５０～９９質量部であることが好ましい。 The dispersion medium disperses the conductive composite particles and improves the film formability of the composition for the electrode catalyst layer. As the dispersion medium, water and alcohols are preferable. Examples of alcohols include methanol and ethanol. The content of the dispersion medium is preferably 50 to 99 parts by mass with respect to 100 parts by mass of the electrode catalyst layer composition.

　電極触媒層用組成物は、バインダーを含むことが好ましい。この場合、バインダーにより電極触媒層用組成物の密着強度を高くすることができる。バインダーとしては、アクリル樹脂、ポリカーボネート、ポリエステル等のポリマー型バインダーや、金属石鹸、金属錯体、金属アルコキシド、金属アルコキシドの加水分解物等のノンポリマー型バインダーが挙げられる。なお、電極触媒層用組成物１００質量部に対して３０質量部を超えるバインダーが含有される場合、電極触媒層用組成物により形成される電極触媒層の厚さが比較的薄いと電極触媒層の水素イオン抵抗が高くなり、当該厚さが比較的厚いと反応ガスの拡散抵抗が増大する。このため、バインダーの含有量は、電極触媒層用組成物：１００質量部に対して、１～３０質量部であることが好ましい。 The electrode catalyst layer composition preferably contains a binder. In this case, the adhesive strength of the electrode catalyst layer composition can be increased by the binder. Examples of the binder include polymer type binders such as acrylic resin, polycarbonate, and polyester, and non-polymer type binders such as metal soaps, metal complexes, metal alkoxides, and hydrolysates of metal alkoxides. In addition, when the binder exceeding 30 mass parts is contained with respect to 100 mass parts of composition for electrode catalyst layers, if the thickness of the electrode catalyst layer formed by the composition for electrode catalyst layers is comparatively thin, an electrode catalyst layer When the thickness is relatively large, the diffusion resistance of the reaction gas increases. For this reason, the binder content is preferably 1 to 30 parts by mass with respect to 100 parts by mass of the electrode catalyst layer composition.

　電極触媒層用組成物は、本発明の目的を損なわない範囲で、必要に応じ、酸化防止剤、レベリング剤、揺変剤、フィラー、応力緩和剤、導電性ポリマー、その他の添加剤等をさらに配合することができる。 The composition for an electrode catalyst layer may further contain an antioxidant, a leveling agent, a thixotropic agent, a filler, a stress relaxation agent, a conductive polymer, other additives, etc., as necessary, as long as the object of the present invention is not impaired. Can be blended.

　導電性複合粒子と分散媒とを含む所望の成分を、常法、例えば、ペイントシェーカー、ボールミル、サンドミル、セントリミル、三本ロール等によって混合し、導電性複合粒子等を分散させることにより、電極触媒層用組成物を製造することができる。無論、通常の攪拌操作によって電極触媒層用組成物を製造することもできる。 The desired components including the conductive composite particles and the dispersion medium are mixed by a conventional method, for example, a paint shaker, ball mill, sand mill, centrimill, three rolls, etc. A layer composition can be produced. Of course, the composition for electrode catalyst layers can also be manufactured by normal stirring operation.

〔電極触媒層〕
　上述のようにして得られた電極触媒層用組成物を、キャリアテープ等の上に所望の厚さになるように湿式塗工した後、乾燥し、場合により焼成することにより、燃料電池の電極触媒層を製造することができる。また、キャリアテープの代わりに、電解質膜上、または集電体である多孔質支持層上に、電極触媒層用組成物を、所望の厚さになるように湿式塗工した後、乾燥し、場合により焼成して電極触媒層を形成することもできる。 (Electrocatalyst layer)
The electrode catalyst layer composition obtained as described above is wet-coated on a carrier tape or the like so as to have a desired thickness, then dried, and optionally fired, so that an electrode for a fuel cell is obtained. A catalyst layer can be produced. Further, instead of the carrier tape, the electrode catalyst layer composition is wet-coated to a desired thickness on the electrolyte membrane or on the porous support layer that is a current collector, and then dried, In some cases, the electrode catalyst layer may be formed by firing.

　湿式塗工法は、スプレーコーティング法、ディスペンサーコーティング法、ナイフコーティング法、スリットコーティング法、ドクターブレード法、スクリーン印刷法、オフセット印刷法またはダイコーティング法のいずれかであることが好ましいが、これに限られるものではなく、あらゆる方法を利用できる。 The wet coating method is preferably, but not limited to, a spray coating method, a dispenser coating method, a knife coating method, a slit coating method, a doctor blade method, a screen printing method, an offset printing method, or a die coating method. Any method can be used.

　上記の方法で得られた燃料電池の電極触媒層は、導電性複合粒子を含有する。この導電性複合粒子は、酸化に対する耐性と強酸に対する耐性とを有する酸化錫微粒子層と、酸化チタン粒子とで構成される。白金ナノ粒子触媒を担持させる酸化錫微粒子層は、酸化チタン粒子との密着性が高く、白金の一酸化炭素被毒への耐性が高い。このため、このような導電性複合粒子を含む電極触媒層用組成物を用いて電極触媒層を形成することにより、高信頼性の燃料電池を製造することができる。 The electrode catalyst layer of the fuel cell obtained by the above method contains conductive composite particles. This conductive composite particle is composed of a tin oxide fine particle layer having resistance to oxidation and resistance to strong acid, and titanium oxide particles. The tin oxide fine particle layer that supports the platinum nanoparticle catalyst has high adhesion to the titanium oxide particles and high resistance to carbon monoxide poisoning of platinum. For this reason, a highly reliable fuel cell can be manufactured by forming an electrode catalyst layer using the composition for electrode catalyst layers containing such electroconductive composite particles.

〔燃料電池〕
　本実施形態の燃料電池は、上述の燃料電池の電極触媒層を備える。図１に、燃料電池の断面構造の模式図の一例を示す。燃料電池１は、電解質膜２０を、燃料極１０と空気極３０との間に挟んだ構成とされている。燃料極１０は、燃料極触媒層１１と、集電体である多孔質支持層１２とを有しており、空気極３０は、空気極触媒層３１と、集電体である多孔質支持層３２を有している。本実施形態の燃料電池１の電極触媒層（１１、３１）に含まれる導電性複合粒子は、酸化に対する耐性と強酸に対する耐性とを有する酸化錫微粒子層と、安価な酸化チタン粒子とで構成されている。このため、この導電性複合粒子は空気極触媒層３１での使用に適している。また、この導電性複合粒子は、白金ナノ粒子触媒の一酸化炭素被毒対策に有効な酸化錫微粒子を有するので、燃料極触媒層１１に適している。燃料電池１としては、固体高分子型燃料電池、直接型メタノール燃料電池、リン酸型燃料電池等が挙げられる。これらのうち、白金ナノ粒子触媒の一酸化炭素被毒の問題が顕著な固体高分子型燃料電池が、本実施形態の電極触媒層の用途としてより適している。燃料電池１が、固体高分子型燃料電池である場合には、電解質膜２０としてフッ素系イオン交換膜等が用いられ、多孔質支持層１２、３２として多孔質のカーボンペーパー等が用いられる。〔Fuel cell〕
The fuel cell of this embodiment includes the above-described fuel cell electrode catalyst layer. FIG. 1 shows an example of a schematic diagram of a cross-sectional structure of a fuel cell. The fuel cell 1 has a configuration in which an electrolyte membrane 20 is sandwiched between a fuel electrode 10 and an air electrode 30. The fuel electrode 10 includes a fuel electrode catalyst layer 11 and a porous support layer 12 that is a current collector. The air electrode 30 includes an air electrode catalyst layer 31 and a porous support layer that is a current collector. 32. The conductive composite particles contained in the electrode catalyst layers (11, 31) of the fuel cell 1 of the present embodiment are composed of a tin oxide fine particle layer having resistance to oxidation and resistance to strong acid, and inexpensive titanium oxide particles. ing. For this reason, the conductive composite particles are suitable for use in the air electrode catalyst layer 31. In addition, the conductive composite particles are suitable for the fuel electrode catalyst layer 11 because they have tin oxide fine particles effective for the carbon monoxide poisoning countermeasure of the platinum nanoparticle catalyst. Examples of the fuel cell 1 include a polymer electrolyte fuel cell, a direct methanol fuel cell, and a phosphoric acid fuel cell. Among these, the polymer electrolyte fuel cell in which the problem of carbon monoxide poisoning of the platinum nanoparticle catalyst is remarkable is more suitable as an application of the electrode catalyst layer of the present embodiment. When the fuel cell 1 is a polymer electrolyte fuel cell, a fluorine ion exchange membrane or the like is used as the electrolyte membrane 20, and porous carbon paper or the like is used as the porous support layers 12 and 32.

　多孔質支持層１２、燃料極触媒層１１、電解質膜２０、空気極触媒層３１、多孔質支持層３２を、この順に積層することにより、燃料電池１を製造することができる。 The fuel cell 1 can be manufactured by laminating the porous support layer 12, the fuel electrode catalyst layer 11, the electrolyte membrane 20, the air electrode catalyst layer 31, and the porous support layer 32 in this order.

　得られた燃料電池１の電極触媒層（１１、３１）に含有される導電性複合粒子は、酸化に対する耐性と強酸に対する耐性とを有する酸化錫微粒子層と、酸化チタン粒子とで構成される。そして、白金ナノ粒子触媒を担持させる酸化錫微粒子層は酸化チタン粒子との密着性が高く、白金の一酸化炭素被毒への耐性が高いので、本実施形態の燃料電池は信頼性が高い。 The conductive composite particles contained in the electrode catalyst layer (11, 31) of the obtained fuel cell 1 are composed of a tin oxide fine particle layer having resistance to oxidation and resistance to strong acid, and titanium oxide particles. And since the tin oxide fine particle layer which carries a platinum nanoparticle catalyst has high adhesiveness with a titanium oxide particle, and the tolerance with respect to carbon monoxide poisoning of platinum is high, the fuel cell of this embodiment has high reliability.

　以下に、実施例により、本発実施形態を詳細に説明するが、本発明はこれらに限定されるものではない。 Hereinafter, the present embodiment will be described in detail by way of examples, but the present invention is not limited thereto.

〔実施例１〕
　５ｍ^２／ｇの比表面積を有する堺化学製酸化チタン粒子（表面が修飾されていない、ルチル型の結晶構造を有する相が主相のＴｉＯ_２粒子）を、０．１Ｍの塩酸で、５０℃、１時間の酸洗浄を行い、続いて水洗を行った。水：８００ｃｍ^３に、この酸化チタン粒子：３０ｇを加え、温度：９０℃で撹拌しながら加熱保持し、酸化チタン粒子を水中に均一に分散させ、酸化チタン粒子含有分散液を調製した。酸化チタン粒子含有分散液の撹拌を続けながら、この酸化チタン粒子含有分散液に、水：２００ｃｍ^３にＳｎＣｌ_４：１５ｇとＳｂＣｌ_３：０．８ｇを溶解した塩化錫水溶液、および水酸化ナトリウム水溶液を、反応液を２５℃、ｐＨ３～９の範囲に保つように、０．５時間かけて滴下し、加水分解させた。その結果、Ｓｂ含有水酸化錫からなる被覆層を表面に析出させた酸化チタン粒子を含有する白色のスラリーを得た。次に、表面にＳｂ含有水酸化錫からなる被覆層を析出させた酸化チタン粒子を濾別し、洗浄した。その後、表面にＳｂ含有水酸化錫からなる被覆層を析出させた酸化チタン粒子を、空気中、５００℃で２時間保持することにより、実施例１の導電性複合粒子（Ｓｂ含有量：５質量％）を得た。ここで、原料のＳｎＣｌ_４はすべてＳｎＯ_２になり、ＳｂＣｌ_３はすべてＳｂになったものとして、Ｓｂの含有量を計算した。Ｓｂの含有量については、他の実施例、比較例においても同様である。 [Example 1]
Titanium chemical titanium oxide particles having a specific surface area of 5 m ² / g (TiO ₂ particles whose surface is not modified and whose phase is a rutile crystal structure is the main phase) are mixed with 0.1 M hydrochloric acid at 50 ° C. An acid wash for 1 hour was performed, followed by a water wash. Water: to 800 cm ^3, the titanium oxide particles: 30 g was added, temperature was stirred at 90 ° C. was heated held with, uniformly dispersing titanium oxide particles in water was prepared containing titanium oxide particles dispersion. While continuing to stir the titanium oxide particle-containing dispersion, a tin chloride aqueous solution and a sodium hydroxide aqueous solution in which SnCl ₄ : 15 g and SbCl ₃ : 0.8 g were dissolved in water: 200 cm ³ were added to the titanium oxide particle-containing dispersion. Then, the reaction solution was added dropwise over 0.5 hours so as to be kept at 25 ° C. and pH 3 to 9 to be hydrolyzed. As a result, a white slurry containing titanium oxide particles on which a coating layer made of Sb-containing tin hydroxide was deposited was obtained. Next, the titanium oxide particles having a coating layer made of Sb-containing tin hydroxide deposited on the surface were separated by filtration and washed. Thereafter, the titanium oxide particles having a coating layer made of Sb-containing tin hydroxide deposited on the surface thereof were kept in the air at 500 ° C. for 2 hours, whereby the conductive composite particles of Example 1 (Sb content: 5 mass). %). Here, the content of Sb was calculated on the assumption that all of the raw material SnCl ₄ was SnO ₂ and SbCl ₃ was all Sb. The Sb content is the same in other examples and comparative examples.

〔実施例２〕
　１ｍ^２／ｇの比表面積を有する堺化学製酸化チタン粒子を用いて酸化チタン粒子含有分散液を調製したこと、水：２００ｃｍ^３にＳｎＣｌ_４：４０ｇとＳｂＣｌ_３：２．１ｇを溶解して塩化錫水溶液を調製したこと、酸化チタン粒子含有分散液に塩化錫水溶液および水酸化ナトリウム水溶液を滴下する時間を１時間としたこと以外は、実施例１と同様にして、実施例２の導電性複合粒子（Ｓｂ含有量：５質量％）を得た。 [Example 2]
Titanium oxide particle-containing dispersion was prepared using Sakai Chemical Titanium Oxide Particles having a specific surface area of 1 m ² / g. Water: 200 cm ³ dissolved SnCl ₄ : 40 g and SbCl ₃ : 2.1 g. The conductive composite of Example 2 was prepared in the same manner as in Example 1, except that an aqueous tin solution was prepared and that the time for dropping the aqueous tin chloride solution and the aqueous sodium hydroxide solution to the titanium oxide particle-containing dispersion was 1 hour. Particles (Sb content: 5% by mass) were obtained.

〔実施例３〕
　水：２００ｃｍ^３にＳｎＣｌ_４：４０ｇとＳｂＣｌ_３：２．１ｇを溶解して塩化錫水溶液を調製したこと、酸化チタン粒子含有分散液に塩化錫水溶液および水酸化ナトリウム水溶液を滴下する時間を３分としたこと、表面にＳｂ含有水酸化錫からなる被覆層を析出させた酸化チタン粒子（濾別され、洗浄されたもの）を、窒素中、１０００℃で１時間保持したこと以外は、実施例１と同様にして、実施例３の導電性複合粒子（Ｓｂ含有量：５質量％）を得た。 Example 3
Water: SnCl ₄ : 40 g and SbCl ₃ : 2.1 g were dissolved in 200 cm ³ to prepare a tin chloride aqueous solution, and the time for dropping the tin chloride aqueous solution and the sodium hydroxide aqueous solution to the titanium oxide particle-containing dispersion was 3 minutes. Example 1 except that the titanium oxide particles having a coating layer made of Sb-containing tin hydroxide deposited on the surface thereof (filtered and washed) were kept in nitrogen at 1000 ° C. for 1 hour. In the same manner as in Example 1, conductive composite particles of Example 3 (Sb content: 5% by mass) were obtained.

〔比較例１〕
　水：８００ｃｍ^３に、５ｍ^２／ｇの比表面積を有する堺化学製酸化チタン粒子：３０ｇと信越化学工業製水溶性シランカップリング剤（３－アミノプロピルトリメトキシシラン）：１．５ｇとを加え、温度：９０℃で撹拌しながら加熱保持し、酸化チタン粒子を水中に均一に分散させ、酸化チタン粒子含有分散液を調製した。撹拌を続けながら、この酸化チタン粒子含有分散液に、水：２００ｃｍ^３にＳｎＣｌ_４：４０ｇとＳｂＣｌ_３：２．１ｇを溶解した塩化錫水溶液、および３５ｗｔ％水酸化ナトリウム水溶液を、反応液を２５℃、ｐＨ３～９の範囲に保つように、０．５時間かけて滴下し、加水分解させた。その結果、Ｓｂ含有水酸化錫からなる被覆層を表面に析出させた酸化チタン粒子を含有する白色のスラリーを得た。次に、表面にＳｂ含有水酸化錫からなる被覆層を析出させた酸化チタン粒子を濾別し、洗浄した。その後、表面にＳｂ含有水酸化錫からなる被覆層を析出させた酸化チタン粒子を、空気中、５００℃で２時間保持することにより、比較例１の導電性複合粒子（Ｓｂ含有量：５質量％）を得た。 [Comparative Example 1]
Water: 800 cm ³ , Tsubame Chemical titanium oxide particles having a specific surface area of 5 m ² / g: 30 g and Shin-Etsu Chemical water-soluble silane coupling agent (3-aminopropyltrimethoxysilane): 1.5 g The temperature was maintained while stirring at 90 ° C., and the titanium oxide particles were uniformly dispersed in water to prepare a dispersion containing titanium oxide particles. While continuing stirring, this titanium oxide particle-containing dispersion was mixed with a tin chloride aqueous solution in which SnCl ₄ : 40 g and SbCl ₃ : 2.1 g were dissolved in water: 200 cm ³ , and a 35 wt% sodium hydroxide aqueous solution. The mixture was added dropwise over 0.5 hours so as to maintain the temperature in the range of 3 ° C. and pH 3 to 9 to cause hydrolysis. As a result, a white slurry containing titanium oxide particles on which a coating layer made of Sb-containing tin hydroxide was deposited was obtained. Next, the titanium oxide particles having a coating layer made of Sb-containing tin hydroxide deposited on the surface were separated by filtration and washed. Thereafter, the titanium oxide particles having a coating layer made of Sb-containing tin hydroxide deposited on the surface thereof are kept in air at 500 ° C. for 2 hours, whereby the conductive composite particles of Comparative Example 1 (Sb content: 5 mass). %).

〔比較例２〕
　水：８００ｃｍ^３に、５ｍ^２／ｇの比表面積を有する堺化学製酸化チタン粒子：３０ｇを加え、温度：９０℃で撹拌しながら加熱保持し、酸化チタン粒子を水中に均一に分散させ、酸化チタン粒子含有分散液を調製した。この酸化チタン粒子含有分散液に、水：２００ｃｍ^３にＳｎＣｌ_４：７５ｇとＳｂＣｌ_３：９．０３ｇを溶解した塩化錫水溶液を、反応液を２５℃、ｐＨ３～９の範囲に保つように、３分間かけて滴下し、酸化チタン粒子表面に、Ｓｂ含有水酸化錫からなる被覆層を析出させた。次に、表面にＳｂ含有水酸化錫からなる被覆層を析出させた酸化チタン粒子を濾別し、洗浄した。その後、表面にＳｂ含有水酸化錫からなる被覆層を析出させた酸化チタン粒子を、空気中、４００℃で２時間保持することにより、比較例２の導電性複合粒子（Ｓｂ含有量：５質量％）を得た。 [Comparative Example 2]
Water: 30 cm of Titanium Chemical Titanium Particles having a specific surface area of 5 m ² / g is added to 800 cm ³ , and the temperature is kept at 90 ° C. with stirring to disperse the titanium oxide particles uniformly in water and oxidize. A dispersion containing titanium particles was prepared. In this titanium oxide particle-containing dispersion, an aqueous tin chloride solution in which SnCl ₄ : 75 g and SbCl ₃ : 9.03 g are dissolved in water: 200 cm ³ is added to the reaction liquid at 25 ° C. and pH 3-9. It was dropped over a period of time to deposit a coating layer made of Sb-containing tin hydroxide on the surface of the titanium oxide particles. Next, the titanium oxide particles having a coating layer made of Sb-containing tin hydroxide deposited on the surface were separated by filtration and washed. Thereafter, the titanium oxide particles having a coating layer made of Sb-containing tin hydroxide deposited on the surface are kept in air at 400 ° C. for 2 hours, whereby the conductive composite particles of Comparative Example 2 (Sb content: 5 mass). %).

〔比較例３〕
　５ｍ^２／ｇの比表面積を有する堺化学製酸化チタン粒子に０．００１Ｍの塩酸で、２０℃、０．５時間の酸洗浄を行った後、水洗を行うことなく酸化チタン粒子含有分散液を調製したこと、表面にＳｂ含有水酸化錫からなる被覆層を析出させた酸化チタン粒子（濾別され、洗浄されたもの）を保持する温度を４００℃としたこと以外は、実施例１と同様にして、比較例３の導電性複合粒子（Ｓｂ含有量：５質量％）を得た。 [Comparative Example 3]
A titanium oxide particle-containing dispersion having a specific surface area of 5 m ² / g was subjected to acid cleaning with 0.001M hydrochloric acid at 20 ° C. for 0.5 hour, and then the titanium oxide particle-containing dispersion without water washing. The same as in Example 1 except that the temperature at which the titanium oxide particles (the one filtered and washed) on which the coating layer made of Sb-containing tin hydroxide was deposited was 400 ° C. was prepared. Thus, conductive composite particles of Comparative Example 3 (Sb content: 5% by mass) were obtained.

〔参考例１〕
　４．３ｍ^２／ｇの比表面積を有する堺化学製酸化チタン粒子を、参考例１として使用した。 [Reference Example 1]
Titanium chemical titanium oxide particles having a specific surface area of 4.3 m ² / g were used as Reference Example 1.

〔参考例２〕
　７２ｍ^２／ｇの比表面積を有する三菱マテリアル製アンチモンドープ酸化錫粒子（製品名：Ｔ－１）を、参考例２として使用した。 [Reference Example 2]
Antimony-doped tin oxide particles (product name: T-1) manufactured by Mitsubishi Materials having a specific surface area of 72 m ² / g were used as Reference Example 2.

〔測定方法〕
　実施例１で作製した導電性複合粒子を、カールツァイス製走査型電子顕微鏡（型番：ＵＬＴＲＡ５５）で観察した（図２）。次に、実施例１で作製した導電性複合粒子を、日本電子製透過型電子顕微鏡（型番：ＪＥＭ－２０１０Ｆ）で観察し、導電性複合粒子の透過型電子顕微鏡写真を撮影した（図３、６）。また、この透過型電子顕微鏡付属のＥＤＳを用い、透過型電子顕微鏡写真を撮影した視野と同じ視野（図３と同じ視野）でＴｉマッピングとＳｎマッピングを行った（図４、５）。また、実施例１～３、比較例１と３で作製した導電性複合粒子を、ＦＥＩ製高分解能透過型電子顕微鏡（型番：ＣＭ２０）で観察し、高分解能透過型電子顕微鏡像を得た（図７～９、１３、１７）。〔Measuring method〕
The conductive composite particles produced in Example 1 were observed with a scanning electron microscope (model number: ULTRA55) manufactured by Carl Zeiss (FIG. 2). Next, the conductive composite particles produced in Example 1 were observed with a transmission electron microscope (model number: JEM-2010F) manufactured by JEOL, and a transmission electron micrograph of the conductive composite particles was taken (FIG. 3, FIG. 3). 6). Moreover, Ti mapping and Sn mapping were performed using the EDS attached to the transmission electron microscope with the same field of view (the same field of view as FIG. 3) as the field of view of the transmission electron micrograph (FIGS. 4 and 5). Further, the conductive composite particles produced in Examples 1 to 3 and Comparative Examples 1 and 3 were observed with a high-resolution transmission electron microscope (model number: CM20) manufactured by FEI, and a high-resolution transmission electron microscope image was obtained ( 7-9, 13, 17).

　次に、実施例１で作製した導電性複合粒子の高分解能透過型電子顕微鏡像において、酸化チタン粒子表面に平行な酸化チタンの格子像の長さに対する、上記酸化チタンの格子像に平行な酸化錫の格子像の長さを測定した。ここで、高分解能透過型電子顕微鏡像において、酸化チタン粒子表面に平行な酸化チタンの格子像とは、高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子の界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタン粒子の表面（すなわち酸化チタン粒子と酸化錫微粒子との界面）と、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の酸化チタンの格子像と、のなす角度の絶対値が１０°以内である格子像をいう。
　ここで、高分解能透過型電子顕微鏡像において、酸化チタンを表す領域のコントラストが、酸化錫微粒子を表す領域のコントラストに変化する点をつなげた線を、酸化チタン粒子と酸化錫微粒子の界面（酸化チタン粒子の表面）とした。格子像（格子縞）が観察される結晶方位が酸化チタン粒子の表面に対し傾いている場合や、酸化チタン粒子の表面に凹凸がある場合には、高分解能透過型電子顕微鏡像で観察される酸化チタン粒子と酸化錫微粒子の界面が凹凸していることがある。この場合は、界面の山の頂点と谷の頂点の中間点を、界面の中心とした。
　また、高分解能透過型電子顕微鏡像において酸化チタンの格子像に平行な酸化錫の格子像とは、高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子の界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、上述の酸化チタンの格子像と、酸化チタン粒子と酸化錫微粒子界面から４～８層目の酸化錫の格子像と、のなす角度の絶対値が１０°以下である格子像をいう。 Next, in the high-resolution transmission electron microscope image of the conductive composite particles produced in Example 1, the oxidation parallel to the lattice image of the titanium oxide with respect to the length of the lattice image of the titanium oxide parallel to the surface of the titanium oxide particles. The length of the tin lattice image was measured. Here, in the high resolution transmission electron microscope image, the lattice image of titanium oxide parallel to the surface of the titanium oxide particles is the center of the interface between the titanium oxide particles and the tin oxide fine particles in the high resolution transmission electron microscope image. Within a region parallel to the interface: width: 50 nm, thickness: 5 nm, the surface of the titanium oxide particles (that is, the interface between the titanium oxide particles and the tin oxide fine particles) and the interface between the titanium oxide particles and the tin oxide fine particles are 4 to This refers to a lattice image in which the absolute value of the angle formed by the lattice image of the eighth layer of titanium oxide is within 10 °.
Here, in the high-resolution transmission electron microscope image, a line connecting points where the contrast of the region representing titanium oxide changes to the contrast of the region representing tin oxide fine particles is represented by an interface between the titanium oxide particles and the tin oxide fine particles (oxidation). Surface of titanium particles). If the crystal orientation in which the lattice image (lattice stripe) is observed is tilted with respect to the surface of the titanium oxide particles, or if the surface of the titanium oxide particles is uneven, the oxidation observed with a high-resolution transmission electron microscope image The interface between the titanium particles and the tin oxide fine particles may be uneven. In this case, the center of the interface is the midpoint between the peak of the interface peak and the peak of the valley.
In addition, the lattice image of tin oxide parallel to the lattice image of titanium oxide in the high resolution transmission electron microscope image is the same as the interface between the titanium oxide particle and the tin oxide fine particle in the high resolution transmission electron microscope image. Between the above-described lattice image of titanium oxide and the lattice image of tin oxide in the fourth to eighth layers from the interface between the titanium oxide particles and the tin oxide fine particles in a region parallel to the width: 50 nm and thickness: 5 nm A lattice image whose absolute value is 10 ° or less.

　具体的には、まず、図７に示す実施例１の高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子との界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域を決定した。この領域内で、酸化チタン粒子表面と、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の酸化チタンの格子像とのなす角度の絶対値を測定した。また、同じ領域内で、酸化チタン粒子と酸化錫微粒子との界面から４層目の酸化チタンの格子像と、酸化チタン粒子と酸化錫微粒子界面から４層目の酸化錫の格子像とのなす角度の絶対値を測定した。同様に、酸化チタン粒子と酸化錫微粒子との界面から５～８層目の酸化チタンの格子像に対し、酸化チタン粒子と酸化錫微粒子との界面から５～８層目の酸化錫の格子像がなす角度の絶対値を、それぞれ測定した。 Specifically, first, in the high-resolution transmission electron microscope image of Example 1 shown in FIG. 7, from the center of the interface between the titanium oxide particles and the tin oxide fine particles, the width parallel to the interface: 50 nm, the thickness: A 5 nm region was determined. Within this region, the absolute value of the angle formed between the surface of the titanium oxide particles and the lattice image of the fourth to eighth layers of titanium oxide from the interface between the titanium oxide particles and the tin oxide fine particles was measured. Further, in the same region, a lattice image of the fourth layer titanium oxide from the interface between the titanium oxide particles and the tin oxide fine particles and a lattice image of the fourth layer tin oxide from the interface between the titanium oxide particles and the tin oxide fine particles are formed. The absolute value of the angle was measured. Similarly, the lattice image of the fifth to eighth layers of titanium oxide from the interface between the titanium oxide particles and the tin oxide fine particles, and the lattice image of the fifth to eighth layers of tin oxide from the interface between the titanium oxide particles and the tin oxide fine particles. The absolute value of the angle formed by each was measured.

　次に、図７に示す高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子との界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の酸化チタンの格子像それぞれについて、酸化チタン粒子表面に対する角度の絶対値が１０°以下の酸化チタンの格子像の長さ（Ｌｔ）を測定した。また、同じ領域内で、酸化チタン粒子と酸化錫微粒子との界面から４層目の酸化錫の格子像について、酸化チタン粒子と酸化錫微粒子との界面から４層目の酸化チタンの格子像に対する角度の絶対値が、１０°以下の酸化錫の格子像の長さ（Ｌｓ）を測定した。得られたＬｔとＬｓから、〔（Ｌｓ／Ｌｔ）×１００〕を算出した。同様に、酸化チタン粒子と酸化錫微粒子との界面から５～８層目の酸化チタンの格子像それぞれに対し、酸化チタン粒子と酸化錫微粒子との界面から５～８層目の酸化錫の格子像とのなす角度の絶対値が１０°以下の酸化錫の格子像の長さ（Ｌｓ）を測定した。このように、酸化チタンの格子像の４層目と酸化錫の格子像の４層目、酸化チタンの格子像の５層目と酸化錫の格子像の５層目、のように、各層毎に測定されたＬｓとＬｔを用いて〔（Ｌｓ／Ｌｔ）×１００〕を算出した。そして、酸化チタン粒子と酸化錫微粒子との界面から４～８層における〔（Ｌｓ／Ｌｔ）×１００〕の平均を求めた。図２１に、（Ｌｓ／Ｌｔ）×１００〕を求めるために測定した箇所を説明するための模式図を示す。図２１において、ＳｎＯ_２の４層目とＴｉＯ_２の４層目、ＳｎＯ_２の５層目とＴｉＯ_２の５層目のように、酸化チタン粒子と酸化錫微粒子との界面から４～８層の各層毎にＬｓとＬｔを測定し、〔（Ｌｓ／Ｌｔ）×１００〕を算出し、その平均を求めた。実施例２と３、比較例３で作製した導電性複合粒子についても、実施例１（図７）の場合と同様にして、〔（Ｌｓ／Ｌｔ）×１００〕を算出した。なお、本実施例では角度の絶対値を測定した領域と同じ領域について、Ｌｓ及びＬｔを測定したが、角度の絶対値を測定した領域とは異なる領域について測定を行ってもよい。
　以上のような高分解能透過型電子顕微鏡像を用いた測定を、１つの導電性複合粒子の１以上の領域について行った。 Next, in the high-resolution transmission electron microscope image shown in FIG. 7, the titanium oxide is within the width: 50 nm, thickness: 5 nm region parallel to the interface from the center of the interface between the titanium oxide particles and the tin oxide fine particles. Measure the length (Lt) of the titanium oxide lattice image whose absolute angle with respect to the titanium oxide particle surface is 10 ° or less for each of the fourth to eighth layer titanium oxide lattice images from the interface between the particles and the tin oxide fine particles. did. Further, in the same region, the lattice image of the fourth layer of tin oxide from the interface between the titanium oxide particles and the tin oxide fine particles, and the lattice image of the fourth layer of titanium oxide from the interface between the titanium oxide particles and the tin oxide fine particles. The length (Ls) of the lattice image of tin oxide having an absolute angle value of 10 ° or less was measured. [(Ls / Lt) × 100] was calculated from the obtained Lt and Ls. Similarly, for the lattice images of the fifth to eighth layers of titanium oxide from the interface between the titanium oxide particles and the tin oxide fine particles, the lattice of the fifth to eighth layers of tin oxide from the interface between the titanium oxide particles and the tin oxide fine particles. The length (Ls) of the lattice image of tin oxide having an absolute value of 10 ° or less with the image was measured. Thus, the fourth layer of the lattice image of titanium oxide, the fourth layer of the lattice image of tin oxide, the fifth layer of the lattice image of titanium oxide, and the fifth layer of the lattice image of tin oxide. [(Ls / Lt) × 100] was calculated using the measured Ls and Lt. Then, the average of [(Ls / Lt) × 100] in 4 to 8 layers was determined from the interface between the titanium oxide particles and the tin oxide fine particles. FIG. 21 is a schematic diagram for explaining a location measured for obtaining (Ls / Lt) × 100]. In FIG. 21, 4 to 8 layers from the interface between the titanium oxide particles and the tin oxide fine particles, such as the fourth layer of SnO _{2 and} the fourth layer of TiO ₂ , the fifth layer of SnO _{2 and} the fifth layer of TiO _2. Ls and Lt were measured for each layer, [(Ls / Lt) × 100] was calculated, and the average was obtained. For the conductive composite particles produced in Examples 2 and 3 and Comparative Example 3, [(Ls / Lt) × 100] was calculated in the same manner as in Example 1 (FIG. 7). In this embodiment, Ls and Lt are measured for the same region as the region where the absolute value of the angle is measured, but measurement may be performed for a region different from the region where the absolute value of the angle is measured.
Measurement using the high-resolution transmission electron microscope image as described above was performed for one or more regions of one conductive composite particle.

　実施例１～３、比較例１～３、参考例１と２で作製した導電性複合粒子のＢＥＴ比表面積を測定した。ＢＥＴ比表面積は、各例で作製された導電性複合粒子１．０ｇを対象に、ＱＵＡＮＴＡＣＨＲＯＭＥ社製窒素吸着測定装置（型番：ＡＵＴＯＳＯＲＢ－１）を用いて、窒素吸着によるＢＥＴ法により測定した。 The BET specific surface area of the conductive composite particles produced in Examples 1 to 3, Comparative Examples 1 to 3, and Reference Examples 1 and 2 was measured. The BET specific surface area was measured by a BET method based on nitrogen adsorption, using 1.0 g of the conductive composite particles produced in each example, using a nitrogen adsorption measuring device (model number: AUTOSORB-1) manufactured by QUANTACHROME.

　実施例１～３、比較例１～３、参考例１と２で作製した導電性複合粒子の圧粉体抵抗率を、三菱化学アナリティック製粉体抵抗測定システム（型番：ＭＣＰ－ＰＤ５１）型を用い、試料質量（測定対象となる導電性複合粒子の質量）を５．０ｇとし、９．８ＭＰａの圧力下で測定した。 The powder resistivity of the conductive composite particles produced in Examples 1 to 3, Comparative Examples 1 to 3, and Reference Examples 1 and 2 was measured using a powder resistance measurement system (model number: MCP-PD51) manufactured by Mitsubishi Chemical Analytic. The sample mass (the mass of the conductive composite particles to be measured) was 5.0 g, and measurement was performed under a pressure of 9.8 MPa.

　実施例１～３、比較例１～３、参考例１と２で作製した導電性複合粒子の密着性を、次の方法で測定した。試料（各例で作成した導電性複合粒子）：１００ｇ、５ｍｍφのＺｒＯ_２ボール：３００ｇ、エタノール：１００ｇを、３００ｃｍ^３の円筒状の密閉できるポリ容器に充填し、ボールミルで１２０ｒｐｍ、１時間粉砕した。粉砕後の試料を、カールツァイス製走査型電子顕微鏡により観察した。剥離の見られた酸化錫微粒子の割合を調べ、この割合を密着性とした。ここで、走査型電子顕微鏡画像（特に反射電子像）中の酸化錫微粒子層において比較的暗い領域を、酸化錫微粒子が剥離した領域であると判断した。そして、走査型電子顕微鏡画像において剥離していると判断された領域の面積を求め、この面積を同じ走査型電子顕微鏡画像中の酸化錫微粒子の面積で除し、その値を剥離の見られた酸化錫微粒子の割合とした。 The adhesion of the conductive composite particles produced in Examples 1 to 3, Comparative Examples 1 to 3, and Reference Examples 1 and 2 was measured by the following method. Sample (conductive composite particles prepared in each example): 100 g, 5 mmφ ZrO ₂ balls: 300 g, ethanol: 100 g were filled into a 300 cm ³ cylindrical sealable plastic container and pulverized with a ball mill at 120 rpm for 1 hour. . The crushed sample was observed with a scanning electron microscope manufactured by Carl Zeiss. The ratio of the tin oxide fine particles in which peeling was observed was examined, and this ratio was defined as adhesion. Here, it was determined that the relatively dark region in the tin oxide fine particle layer in the scanning electron microscope image (particularly the reflected electron image) was a region where the tin oxide fine particles were peeled off. Then, the area of the region judged to be peeled in the scanning electron microscope image was obtained, and this area was divided by the area of the tin oxide fine particles in the same scanning electron microscope image, and the value was seen to peel. The ratio was tin oxide fine particles.

　実施例１～３、比較例１～３で作製した導電性複合粒子のＸ線回折パターンを、Ｂｒｕｋｅｒ製Ｘ線回折装置（型番：ＭＸＰ－１８ＶＡＨＦ）で測定し、得られたＸ線回折パターンから結晶構造を同定した。なお、測定においては、ステップ幅が半値幅の１／４程度となるようにステップ幅を設定し、メインピークが１００００ｃｐｓ以上になるように積算時間を設定した。 The X-ray diffraction patterns of the conductive composite particles prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were measured with a Bruker X-ray diffractometer (model number: MXP-18VAHF). From the obtained X-ray diffraction patterns The crystal structure was identified. In the measurement, the step width was set so that the step width was about ¼ of the half width, and the integration time was set so that the main peak was 10000 cps or more.

　実施例１～３で作製した導電性複合粒子を、日本電子製透過型電子顕微鏡（型番：ＣＭ２０）で観察し、導電性複合粒子の透過型電子顕微鏡写真と電子線回折図形を得た（図１０～１２、１４～１６、１８～２０）。なお、電子線のビーム径を１ｍｍ程度とし、［１１０］方向の回折点が観察されるように電子線の入射方位を調整して電子線回折図形を得た。 The conductive composite particles produced in Examples 1 to 3 were observed with a transmission electron microscope (model number: CM20) manufactured by JEOL, and transmission electron micrographs and electron beam diffraction patterns of the conductive composite particles were obtained (Fig. 10-12, 14-16, 18-20). An electron beam diffraction pattern was obtained by adjusting the incident direction of the electron beam so that the beam diameter of the electron beam was about 1 mm and a diffraction point in the [110] direction was observed.

〔実施例１の結果〕
　図２に、実施例１で作製した導電性複合粒子の走査型電子顕微鏡写真を示す。また、図３に実施例１で作製した導電性複合粒子の透過型電子顕微鏡写真を、図４に透過型電子顕微鏡付属のＥＤＳによるＴｉマッピングを、図５に同装置によるＳｎマッピングを示す。図２～５から、導電性複合粒子は、酸化チタン粒子の表面が、多孔質の酸化錫微粒子層で被覆されていることがわかった。
　ここで、前述のように測定したＢＥＴ比表面積からＢＥＴ粒径を算出し、ＢＥＴ粒径が、走査型電子顕微鏡像を用いて測定された粒子径の１．５倍以上である場合に多孔質であると判断した。なお、ＢＥＴ粒径は次の式で求められる。
　ＢＥＴ粒径［ｎｍ］＝１／（（酸化チタンの重量比率×酸化チタンの真密度＋酸化錫の重量比率×酸化錫の真密度）×ＢＥＴ比表面積）×１０^－１５ [Results of Example 1]
FIG. 2 shows a scanning electron micrograph of the conductive composite particles produced in Example 1. Further, FIG. 3 shows a transmission electron micrograph of the conductive composite particles produced in Example 1, FIG. 4 shows Ti mapping by EDS attached to the transmission electron microscope, and FIG. 5 shows Sn mapping by the apparatus. 2 to 5, it was found that the surface of the titanium oxide particles of the conductive composite particles was coated with a porous tin oxide fine particle layer.
Here, the BET particle size is calculated from the BET specific surface area measured as described above, and is porous when the BET particle size is 1.5 times or more of the particle size measured using a scanning electron microscope image. It was judged that. Note that the BET particle size is obtained by the following equation.
BET particle size [nm] = 1 / ((weight ratio of titanium oxide × true density of titanium oxide + weight ratio of tin oxide × true density of tin oxide) × BET specific surface area) × 10 ⁻¹⁵

　次に、図６に、実施例１で作製した導電性複合粒子の透過型電子顕微鏡写真を、図７に、酸化チタン粒子と酸化錫微粒子との界面部を拡大した高分解能透過型電子顕微鏡像を示す。図７に示す高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子の界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタン粒子表面とのなす角度の絶対値が１０°以内である酸化チタンの格子像、すなわち、酸化チタン粒子表面と平行な酸化チタンの格子像の存在を、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の全ての酸化チタンの格子像について確認した。また、図７に示す高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子との界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタンの格子像とのなす角度の絶対値が１０°以下である酸化錫の格子像、すなわち、酸化チタンの格子像に平行な酸化錫の格子像の存在を、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の全ての酸化錫の格子像について確認した。 Next, FIG. 6 shows a transmission electron micrograph of the conductive composite particles produced in Example 1, and FIG. 7 shows a high-resolution transmission electron microscope image in which the interface between the titanium oxide particles and the tin oxide fine particles is enlarged. Indicates. In the high-resolution transmission electron microscope image shown in FIG. 7, from the center of the interface between the titanium oxide particles and the tin oxide fine particles, within the region of width: 50 nm and thickness: 5 nm parallel to the interface, The presence of a lattice image of titanium oxide having an absolute value of 10 ° or less, that is, a lattice image of titanium oxide parallel to the surface of the titanium oxide particle, is expressed in 4 to 8 layers from the interface between the titanium oxide particle and the tin oxide fine particle. All the lattice images of titanium oxide in the eye were confirmed. Further, in the high-resolution transmission electron microscope image shown in FIG. 7, from the center of the interface between the titanium oxide particles and the tin oxide fine particles, within the region parallel to the interface: width: 50 nm, thickness: 5 nm, The presence of a lattice image of tin oxide having an absolute value of 10 ° or less with respect to the lattice image, that is, the lattice image of tin oxide parallel to the lattice image of titanium oxide is defined as the interface between the titanium oxide particles and the tin oxide fine particles. Thus, the lattice images of all the tin oxides in the fourth to eighth layers were confirmed.

　次に、図７に示す高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子との界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の酸化チタンの格子像について、酸化チタン粒子の表面に対する角度の絶対値が１０°以下の酸化チタンの格子像の長さ（Ｌｔ）を測定した。また、同じ領域内で、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の酸化錫の格子像について、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の酸化チタンの格子像それぞれに対する角度の絶対値が１０°以下の酸化錫の格子像の長さ（Ｌｓ）を測定した。酸化チタンの４層目と酸化錫の４層目、酸化チタンの５層目と酸化錫の５層目、のように、各層毎のＬｓとＬｔを対応させて各層毎に〔（Ｌｓ／Ｌｔ）×１００〕を算出して平均を求めた。表１に、実施例１で作製した導電性複合粒子の各層のＬｓ、Ｌｔ、〔（Ｌｓ／Ｌｔ）×１００〕、及びそれらの平均値を示す。表１からわかるように、〔（Ｌｓ／Ｌｔ）×１００〕は、８０％以上であった。表２にも、実施例１～３、比較例１～３、参考例１、２で作成した導電性複合粒子の〔（Ｌｓ／Ｌｔ）×１００〕の平均値を示す。表２には、酸化チタン粒子の表面での酸化錫微粒子の状態、及び酸化錫微粒子層の状態（多孔質か否か）も示す。また、表２に、実施例１で作製した導電性複合粒子のＢＥＴ比表面積、圧粉体抵抗率、密着性の結果を示す。 Next, in the high-resolution transmission electron microscope image shown in FIG. 7, the titanium oxide is within the width: 50 nm, thickness: 5 nm region parallel to the interface from the center of the interface between the titanium oxide particles and the tin oxide fine particles. Measure the length (Lt) of the titanium oxide lattice image with an absolute value of 10 ° or less of the angle with respect to the surface of the titanium oxide particle for the fourth to eighth layers of the titanium oxide lattice image from the interface between the particles and the tin oxide fine particles. did. Further, within the same region, the lattice image of the fourth to eighth layer tin oxide from the interface between the titanium oxide particles and the tin oxide fine particles, and the fourth to eighth layer titanium oxides from the interface between the titanium oxide particles and the tin oxide fine particles. The length (Ls) of a tin oxide lattice image having an absolute value of 10 ° or less with respect to each of the lattice images was measured. For example, the fourth layer of titanium oxide and the fourth layer of tin oxide, the fifth layer of titanium oxide, and the fifth layer of tin oxide are associated with Ls and Lt for each layer [(Ls / Lt ) × 100] and the average was obtained. Table 1 shows Ls, Lt, [(Ls / Lt) × 100] of each layer of the conductive composite particles produced in Example 1, and an average value thereof. As can be seen from Table 1, [(Ls / Lt) × 100] was 80% or more. Table 2 also shows the average value of [(Ls / Lt) × 100] of the conductive composite particles prepared in Examples 1 to 3, Comparative Examples 1 to 3, and Reference Examples 1 and 2. Table 2 also shows the state of the tin oxide fine particles on the surface of the titanium oxide particles and the state of the tin oxide fine particle layer (whether it is porous or not). Table 2 shows the results of the BET specific surface area, the green compact resistivity, and the adhesion of the conductive composite particles produced in Example 1.

　次に、表３に、実施例１～３、比較例１～３のＸ線回折の結果を示す。酸化チタン、酸化錫は、いずれもルチル型であった。図９に、実施例１で作製した導電性複合粒子の高分解能透過型電子顕微鏡像を示す。図９に示す高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子の界面の中心から、界面と平行に幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタン粒子表面とのなす角度の絶対値が１０°以内である、酸化チタン粒子表面と平行な酸化チタンの格子像の存在を、酸化チタン粒子と酸化錫微粒子界面から４～８層目の全ての酸化チタンの格子像で確認した。 Next, Table 3 shows the results of X-ray diffraction of Examples 1 to 3 and Comparative Examples 1 to 3. Titanium oxide and tin oxide were both rutile types. FIG. 9 shows a high-resolution transmission electron microscope image of the conductive composite particles produced in Example 1. In the high-resolution transmission electron microscope image shown in FIG. 9, from the center of the interface between the titanium oxide particles and the tin oxide fine particles, within the region of width: 50 nm and thickness: 5 nm in parallel with the interface, The presence of a lattice image of titanium oxide parallel to the surface of the titanium oxide particle, whose absolute value is 10 ° or less, is the lattice image of all titanium oxides in the fourth to eighth layers from the interface between the titanium oxide particle and the tin oxide fine particle. Confirmed with.

　また、図９に示す高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子との界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、上記の酸化チタンの格子像とのなす角度の絶対値が１０°以下である、すなわち上記の酸化チタンの格子像に平行な酸化錫の格子像の存在を、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の全ての酸化錫の格子像について確認した。 Further, in the high-resolution transmission electron microscope image shown in FIG. 9, the above oxidation is performed in the region of width: 50 nm and thickness: 5 nm parallel to the interface from the center of the interface between the titanium oxide particles and the tin oxide fine particles. The absolute value of the angle formed with the lattice image of titanium is 10 ° or less, that is, the presence of the lattice image of tin oxide parallel to the lattice image of titanium oxide is 4 from the interface between the titanium oxide particles and the tin oxide fine particles. The lattice images of all the tin oxides in the eighth to eighth layers were confirmed.

　図１０に、実施例１で作製した導電性複合粒子の透過型電子顕微鏡写真と電子線回折図形を示す。左上の透過型電子顕微鏡写真の白の破線Ａで囲んだ部分の電子線回折図形を、右上（ＴｉＯ_２／ＳｎＯ_２）に示す。なお、破線Ａで囲まれた観察対象となる領域として、酸化錫微粒子と、酸化チタン粒子と、これらの界面とを含み、且つ電子線回折図形が得られる領域及び角度を選定した。また、左上の透過型電子顕微鏡写真の白の破線Ａ中の黒点Ｂで示す酸化チタンの電子線回折図形を、左下（ＴｉＯ_２）に示す。左上の透過型電子顕微鏡写真の白の破線Ａ中の白点Ｃで示す酸化錫の電子線回折図形を、右下（ＳｎＯ_２）に示す。 FIG. 10 shows a transmission electron micrograph and an electron diffraction pattern of the conductive composite particles produced in Example 1. The electron diffraction pattern of the portion surrounded by the white broken line A in the upper left transmission electron micrograph is shown in the upper right (TiO ₂ / SnO ₂ ). In addition, the area | region and angle which contain a tin oxide fine particle, a titanium oxide particle, and these interfaces, and can obtain an electron beam diffraction pattern were selected as an area | region to be observed enclosed with the broken line A. In addition, an electron beam diffraction pattern of titanium oxide indicated by a black dot B in a white broken line A in the upper left transmission electron micrograph is shown in the lower left (TiO ₂ ). The electron diffraction pattern of tin oxide shown by white dots C in broken line A transmission electron micrograph of white in the upper left, shown in the lower right (SnO _2).

　図１１には、実施例１で作製した導電性複合粒子の電子線回折図形を示す。図１１の左上、左下、右下の電子線回折図形は、それぞれ図１０の右上、左下、右下の電子線回折図形と同じである。また、図１１の右上に、酸化チタンの電子線回折図形（左下）と酸化錫の電子線回折図形（右下）を重ね合わせた結果を示す。右上の図からわかるように、酸化チタンの電子線回折図形と酸化錫の電子線回折図形には、ほとんどズレがなかった。 FIG. 11 shows an electron diffraction pattern of the conductive composite particles produced in Example 1. The electron diffraction patterns at the upper left, lower left, and lower right in FIG. 11 are the same as the electron diffraction patterns at the upper right, lower left, and lower right in FIG. 10, respectively. Moreover, the result of superimposing the electron diffraction pattern of titanium oxide (lower left) and the electron diffraction pattern of tin oxide (lower right) on the upper right of FIG. 11 is shown. As can be seen from the upper right figure, there was almost no deviation between the electron diffraction pattern of titanium oxide and the electron diffraction pattern of tin oxide.

　図１２は、実施例１で作製した導電性複合粒子の電子線回折図形と解析結果を示す。上述のように、Ｘ線回折法により、酸化チタンと酸化錫との結晶構造は、ともに正方晶系（ルチル型）であることがわかっているので、酸化チタンの電子線回折図形（左）と酸化錫の電子線回折図形（右）に指数付けを行った。その結果、図１１、図１２から、酸化スズの電子線回折図形と、酸化チタンの電子線回折図形を重ね合わせたとき(図１１右上)、酸化チタンのルチル型の結晶構造の（１１０）面による回折点と、酸化錫のルチル型の結晶構造の（１１０）面による回折点とのずれがほとんどなく、後述するように、酸化チタンの（１１０）面と酸化錫の（１１０）面とが電子線回折図形上で平行であることがわかった。同様に、図１１、１２から、酸化チタンの（１１２）面と酸化錫の（１１２）面が電子線回折図形上で平行であり、酸化チタンの（１１１）面と酸化錫の（１１１）面とが電子線回折図形上で平行であることがわかった。 FIG. 12 shows an electron beam diffraction pattern and analysis results of the conductive composite particles produced in Example 1. As described above, since the crystal structure of titanium oxide and tin oxide is known to be tetragonal (rutile type) by X-ray diffraction, the electron diffraction pattern of titanium oxide (left) and Indexing was performed on the electron diffraction pattern (right) of tin oxide. As a result, from FIG. 11 and FIG. 12, when the electron diffraction pattern of tin oxide and the electron diffraction pattern of titanium oxide are superimposed (upper right of FIG. 11), the (110) plane of the rutile crystal structure of titanium oxide. There is almost no deviation between the diffraction point due to (110) and the diffraction point due to the (110) plane of the rutile-type crystal structure of tin oxide. As will be described later, the (110) plane of titanium oxide and the (110) plane of tin oxide are It was found to be parallel on the electron diffraction pattern. Similarly, from FIGS. 11 and 12, the (112) plane of titanium oxide and the (112) plane of tin oxide are parallel on the electron diffraction pattern, and the (111) plane of titanium oxide and the (111) plane of tin oxide. Are parallel on the electron diffraction pattern.

　図２２に、酸化チタンのルチル型の結晶構造の（１１０）面と、酸化錫のルチル型の結晶構造の（１１０）面とが、電子線回折図形上で平行であることを説明するための図を示す。図２２の右図は、図１０の右上の電子線回折図形を解析したものである。 FIG. 22 illustrates that the (110) plane of the rutile crystal structure of titanium oxide and the (110) plane of the rutile crystal structure of tin oxide are parallel on the electron diffraction pattern. The figure is shown. The right diagram in FIG. 22 is an analysis of the electron diffraction pattern at the upper right in FIG.

　透過型電子顕微鏡で得られる導電性複合粒子の酸化チタンと酸化錫との双方を視野に入れた電子線回折図形（例えば図１０の右上図）において、ダイレクトスポットを始点に、［１１０］の回折点を通るようにして、ダイレクトスポットから［１１０］方向に数えて１個目および２個目の回折点を通る直線を引き、この直線を［１１０］方向の基準線とした。ここで、酸化チタン由来の回折点と酸化錫由来の回折点とが完全には重ならずにずれて観察された場合、基準線はＴｉＯ_２由来とＳｎＯ_２由来の２つの回折点の中間点を通るようにした。この基準線からダイレクトスポットを始点に±５°となる境界線を引いた。ダイレクトスポットから［１１０］方向に数えて３個目および４個目の回折点が、２本の境界線の内側（基準線側）に存在した場合、酸化チタンのルチル型の結晶構造の［１１０］方向と酸化錫のルチル型の結晶構造の［１１０］方向とが平行であると判断した。ルチル型の結晶構造において［１１０］方向は（１１０）面に垂直である。このため、酸化チタンのルチル型の結晶構造の［１１０］方向と酸化錫のルチル型の結晶構造の［１１０］方向とが、電子線回折図形上で平行であることと、酸化チタンのルチル型の結晶構造の（１１０）面と酸化錫のルチル型の結晶構造の（１１０）面とが、電子線回折図形上で平行であることとは、等価である。 In the electron diffraction pattern (for example, the upper right figure of FIG. 10) which considered both the titanium oxide and the tin oxide of the electroconductive composite particle obtained with a transmission electron microscope, the diffraction of [110] starts from a direct spot. A straight line passing through the first and second diffraction points counted from the direct spot in the [110] direction so as to pass through the point was used as a reference line in the [110] direction. Here, when the diffraction point derived from titanium oxide and the diffraction point derived from tin oxide are observed without being completely overlapped, the reference line is an intermediate point between the two diffraction points derived from TiO ₂ and SnO _2. I tried to pass. From this reference line, a boundary line of ± 5 ° was drawn starting from the direct spot. When the third and fourth diffraction spots counted in the [110] direction from the direct spot exist inside the two boundary lines (on the reference line side), the [110] of the rutile crystal structure of titanium oxide. ] Direction and the [110] direction of the rutile crystal structure of tin oxide were judged to be parallel. In the rutile crystal structure, the [110] direction is perpendicular to the (110) plane. For this reason, the [110] direction of the rutile crystal structure of titanium oxide and the [110] direction of the rutile crystal structure of tin oxide are parallel on the electron diffraction pattern, and the rutile type of titanium oxide. It is equivalent that the (110) plane of the crystal structure and the (110) plane of the rutile type crystal structure of tin oxide are parallel on the electron diffraction pattern.

　具体的には、まず、図２２の左図に示すように、透過型電子顕微鏡を用いて、導電性複合粒子の酸化チタン（図２２の左での実線の丸中の白点Ｂ）と酸化錫（図２２の左での一点破線の丸中の白点Ｃ）の双方を視野に入れた領域（図２２の左での破線Ａの丸）を観察し、電子線回折図形を得た（図２２の右図）。神戸大学理学研究科地球惑星科学専攻の瀬戸雄介助教作成のソフトウェアであるＲｅｃｉＰｒｏ（ｖｅｒ．４．２０１）を使用し、カメラ長を１００ｃｍに設定して、この電子線回折図形について、ルチル型の結晶構造の［１１０］の回折点に指数を付した。 Specifically, as shown in the left diagram of FIG. 22, first, using a transmission electron microscope, titanium oxide (white dot B in the solid line circle on the left of FIG. 22) and oxidation of the conductive composite particles. An area where both of tin (white dot C in a circle with a one-dot broken line on the left in FIG. 22) were viewed (observed with a broken line A on the left in FIG. 22) was observed to obtain an electron diffraction pattern ( The right figure of FIG. Using ReciPro (ver. 4.201), software created by Dr. Yusuke Seto, Department of Earth and Planetary Sciences, Graduate School of Science, Kobe University, the camera length was set to 100 cm. An index was assigned to the [110] diffraction point of the structure.

　次に、図２２の右図に示すように、ダイレクトスポット（図２２の右での実線の丸中の白点）を始点に、［１１０］の回折点を通るようにして、ダイレクトスポットから［１１０］方向に数えて１個目および２個目の回折点を通る直線を引いた。この直線を［１１０］方向の基準線（図２２の右での矢印付き実線）とした。この基準線からダイレクトスポットを始点に±５°となる境界線（（図２２の右での２本の矢印付き破線）を引いた。 Next, as shown in the right diagram of FIG. 22, the direct spot (white point in the solid circle on the right in FIG. 22) starts from the direct spot and passes through the diffraction spot [110]. 110] direction, straight lines passing through the first and second diffraction spots were drawn. This straight line was used as a reference line in the [110] direction (solid line with an arrow on the right in FIG. 22). From this reference line, a boundary line (a broken line with two arrows on the right side of FIG. 22) of ± 5 ° was drawn starting from the direct spot.

　図２２の右図では、ダイレクトスポットから［１１０］方向に数えて３個目および４個目の回折点が、２本の境界線の内側（基準線側）に存在していたので、酸化チタンのルチル型の結晶構造の［１１０］方向と、酸化錫のルチル型の結晶構造の［１１０］方向とが、電子線回折図形上で平行であると判断した。
　ルチル型の結晶構造において、［１１０］方向は（１１０）面に垂直である。よって、図２２の右図では、酸化チタンのルチル型の結晶構造の［１１０］方向と、酸化錫のルチル型の結晶構造の［１１０］方向とが、電子線回折図形で平行であったので、酸化チタンのルチル型の結晶構造の（１１０）面と、酸化錫のルチル型の結晶構造の（１１０）面も、電子線回折図形で平行であると判断した。 In the right diagram of FIG. 22, the third and fourth diffraction points counted in the [110] direction from the direct spot are present inside the two boundary lines (on the reference line side). It was determined that the [110] direction of the rutile-type crystal structure and the [110] direction of the rutile-type crystal structure of tin oxide were parallel on the electron diffraction pattern.
In the rutile crystal structure, the [110] direction is perpendicular to the (110) plane. Therefore, in the right diagram of FIG. 22, the [110] direction of the rutile crystal structure of titanium oxide and the [110] direction of the rutile crystal structure of tin oxide are parallel in the electron diffraction pattern. The (110) plane of the rutile crystal structure of titanium oxide and the (110) plane of the rutile crystal structure of tin oxide were also judged to be parallel in the electron diffraction pattern.

〔実施例２の結果〕
　実施例２で作製した導電性複合粒子の高分解能透過型電子顕微鏡像（図１３）中で、酸化チタン粒子と酸化錫微粒子との界面の中心から、界面と平行に幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタン粒子表面とのなす角度の絶対値が１０°以内である、すなわち、酸化チタン粒子表面と平行な酸化チタンの格子像の存在を、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の全ての酸化チタンの格子像について確認した。また、実施例２で作製した導電性複合粒子の高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子との界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタンの格子像とのなす角度の絶対値が１０°以下である、すなわち、酸化チタンの格子像に平行な酸化錫の格子像の存在を、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の全ての酸化錫の格子像について確認した。そして、実施例１と同様に、導電性複合粒子の〔（Ｌｓ／Ｌｔ）×１００〕の平均値を計算した。表２に、実施例２で作製した導電性複合粒子の〔（Ｌｓ／Ｌｔ）×１００〕、酸化チタン粒子の表面での酸化錫微粒子の状態、酸化錫微粒子層の状態、ＢＥＴ比表面積、圧粉体抵抗率、密着性の結果を示す。表３に、実施例２で作製した導電性複合粒子のＸ線回折の結果を示す。 [Results of Example 2]
In the high-resolution transmission electron microscope image (FIG. 13) of the conductive composite particles produced in Example 2, from the center of the interface between the titanium oxide particles and the tin oxide fine particles, the width: 50 nm, the thickness: In the region of 5 nm, the absolute value of the angle formed with the surface of the titanium oxide particles is within 10 °, that is, the presence of a lattice image of titanium oxide parallel to the surface of the titanium oxide particles is expressed as follows. All the lattice images of titanium oxide in the fourth to eighth layers from the interface were confirmed. Further, in the high-resolution transmission electron microscope image of the conductive composite particles produced in Example 2, the width parallel to the interface is 50 nm and the thickness is 5 nm from the center of the interface between the titanium oxide particles and the tin oxide fine particles. In the region, the absolute value of the angle formed with the lattice image of titanium oxide is 10 ° or less, that is, the presence of the lattice image of tin oxide parallel to the lattice image of titanium oxide is expressed as follows: All the lattice images of tin oxide in the 4th to 8th layers from the interface were confirmed. And similarly to Example 1, the average value of [(Ls / Lt) × 100] of the conductive composite particles was calculated. Table 2 shows [(Ls / Lt) × 100] of the conductive composite particles produced in Example 2, the state of the tin oxide fine particles on the surface of the titanium oxide particles, the state of the tin oxide fine particle layer, the BET specific surface area, the pressure. The results of powder resistivity and adhesion are shown. Table 3 shows the results of X-ray diffraction of the conductive composite particles produced in Example 2.

　次に、実施例２で作製した導電性複合粒子について、実施例１の図９～１２と同様の解析を行った結果を、図１３～１６に示す。図１５の右上図を用いて、図２２と同様の解析を行った結果、酸化チタンの（１１０）面と酸化錫の（１１０）面が電子線回折図形上で平行であることがわかった。同様に、酸化チタンの（３３２）面と酸化錫の（３３２）面が電子線回折図形上で平行であり、酸化チタンの（１１３）面と酸化錫の（１１３）面が電子線回折図形上で平行であることがわかった。 Next, the results of the same analysis as in FIGS. 9 to 12 of Example 1 for the conductive composite particles produced in Example 2 are shown in FIGS. As a result of performing the same analysis as FIG. 22 using the upper right view of FIG. 15, it was found that the (110) plane of titanium oxide and the (110) plane of tin oxide were parallel on the electron diffraction pattern. Similarly, the (332) plane of titanium oxide and the (332) plane of tin oxide are parallel on the electron diffraction pattern, and the (113) plane of titanium oxide and the (113) plane of tin oxide are on the electron diffraction pattern. It turned out to be parallel.

〔実施例３の結果〕
　実施例３で作製した導電性複合粒子の高分解能透過型電子顕微鏡像（図１７）中で、酸化チタン粒子と酸化錫微粒子との界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタン粒子表面とのなす角度の絶対値が１０°以内である、すなわち、酸化チタン粒子表面と平行な酸化チタンの格子像の存在を、酸化チタン粒子と酸化錫微粒子界面から４～８層目の全ての酸化チタンの格子像について確認した。また、実施例３で作製した導電性複合粒子の高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子との界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタンの格子像とのなす角度の絶対値が１０°以下である、すなわち、酸化チタンの格子像に平行な酸化錫の格子像の存在を、酸化チタン粒子と酸化錫微粒子界面から４～８層目の全ての酸化錫の格子像について確認した。そして、実施例１と同様に、導電性複合粒子の〔（Ｌｓ／Ｌｔ）×１００〕の平均値を計算した。表２に、実施例３で作製した導電性複合粒子の〔（Ｌｓ／Ｌｔ）×１００〕、酸化チタン粒子の表面での酸化錫微粒子の状態、酸化錫微粒子層の状態、ＢＥＴ比表面積、圧粉体抵抗率、密着性の結果を示す。また、表３に、実施例３で作製した導電性複合粒子のＸ線回折の結果を示す。 [Results of Example 3]
In the high-resolution transmission electron microscope image (FIG. 17) of the conductive composite particles produced in Example 3, from the center of the interface between the titanium oxide particles and the tin oxide fine particles, the width parallel to the interface: 50 nm, the thickness: In the region of 5 nm, the absolute value of the angle formed with the titanium oxide particle surface is within 10 °, that is, the presence of a lattice image of titanium oxide parallel to the titanium oxide particle surface is determined by the interface between the titanium oxide particle and the tin oxide fine particle interface. The lattice images of all titanium oxides in the 4th to 8th layers were confirmed. In the high-resolution transmission electron microscope image of the conductive composite particles produced in Example 3, the width parallel to the interface is 50 nm and the thickness is 5 nm from the center of the interface between the titanium oxide particles and the tin oxide fine particles. In the region, the absolute value of the angle formed with the lattice image of titanium oxide is 10 ° or less, that is, the presence of the lattice image of tin oxide parallel to the lattice image of titanium oxide is defined as the interface between the titanium oxide particle and the tin oxide fine particle interface. Thus, the lattice images of all the tin oxides in the fourth to eighth layers were confirmed. And similarly to Example 1, the average value of [(Ls / Lt) × 100] of the conductive composite particles was calculated. Table 2 shows [(Ls / Lt) × 100] of the conductive composite particles produced in Example 3, the state of the tin oxide fine particles on the surface of the titanium oxide particles, the state of the tin oxide fine particle layer, the BET specific surface area, the pressure. The results of powder resistivity and adhesion are shown. Table 3 shows the results of X-ray diffraction of the conductive composite particles produced in Example 3.

　次に、実施例３で作製した導電性複合粒子について、実施例１の図９～１２と同様の解析を行った結果を、図１７～２０に示す。図１９の右上図を用いて、図２２と同様の解析を行った結果、酸化チタンの（１１０）面と酸化錫の（１１０）面が電子線回折図形上で平行であることがわかった。同様に、酸化チタンの（００１）面と酸化錫の（００１）面が電子線回折図形上で平行であり、酸化チタンの（１－１０）面と酸化錫の（１－１０）面が電子線回折図形上で平行であることがわかった。なお、図１２、図１６、図２０でのいずれの解析結果においても、酸化チタンの（１１０）面と酸化錫の（１１０）面は、電子線回折図形上で平行であった。 Next, the results of conducting the same analysis as in FIGS. 9 to 12 of Example 1 for the conductive composite particles produced in Example 3 are shown in FIGS. As a result of performing the same analysis as in FIG. 22 using the upper right view of FIG. 19, it was found that the (110) plane of titanium oxide and the (110) plane of tin oxide were parallel on the electron diffraction pattern. Similarly, the (001) plane of titanium oxide and the (001) plane of tin oxide are parallel on the electron diffraction pattern, and the (1-10) plane of titanium oxide and the (1-10) plane of tin oxide are electrons. It was found to be parallel on the line diffraction pattern. In any of the analysis results shown in FIGS. 12, 16, and 20, the (110) plane of titanium oxide and the (110) plane of tin oxide were parallel on the electron diffraction pattern.

〔比較例１の結果〕
　図８に、比較例１で作製した導電性複合粒子の酸化チタン粒子と酸化錫微粒子の界面部を拡大した高分解能透過型電子顕微鏡像を示す。図８に示す比較例１で作製した導電性複合粒子の高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子との界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタン粒子表面と、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の酸化チタンの格子像とのなす角度の絶対値が１０°より小さく、酸化チタン粒子表面に対して酸化チタンの格子像は平行であった。 [Results of Comparative Example 1]
FIG. 8 shows a high-resolution transmission electron microscope image in which the interface between the titanium oxide particles and the tin oxide particles of the conductive composite particles produced in Comparative Example 1 is enlarged. In the high-resolution transmission electron microscope image of the conductive composite particles produced in Comparative Example 1 shown in FIG. 8, from the center of the interface between the titanium oxide particles and the tin oxide fine particles, the width parallel to the interface: 50 nm, the thickness: In the region of 5 nm, the absolute value of the angle formed between the surface of the titanium oxide particles and the lattice image of the fourth to eighth layers of titanium oxide from the interface between the titanium oxide particles and the tin oxide fine particles is smaller than 10 °. The lattice image of titanium oxide was parallel to the surface.

　一方、図８に示す比較例１で作製した導電性複合粒子の高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子との界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタンの格子像と、酸化チタン粒子と酸化錫微粒子との界面から４～８層目の酸化錫の格子像とのなす角度の絶対値が、１０°より大きかった。したがって、酸化チタン粒子表面に対して平行な酸化チタンの格子像と、酸化錫の格子像とが平行ではないことがわかった。表２に、比較例１で作製した導電性複合粒子の酸化チタン粒子の表面での酸化錫微粒子の状態、酸化錫微粒子層の状態、ＢＥＴ比表面積、圧粉体抵抗率、密着性の結果を示す。また、表３に、比較例１で作製した導電性複合粒子のＸ線回折の結果を示す。 On the other hand, in the high-resolution transmission electron microscope image of the conductive composite particles produced in Comparative Example 1 shown in FIG. 8, from the center of the interface between the titanium oxide particles and the tin oxide fine particles, the width parallel to the interface: 50 nm, the thickness The absolute value of the angle formed between the lattice image of titanium oxide and the lattice image of tin oxide in the fourth to eighth layers from the interface between the titanium oxide particles and the tin oxide fine particles is larger than 10 ° within the 5 nm region. It was. Therefore, it was found that the lattice image of titanium oxide parallel to the surface of the titanium oxide particles was not parallel to the lattice image of tin oxide. Table 2 shows the results of the state of the tin oxide fine particles, the state of the tin oxide fine particle layer, the BET specific surface area, the green compact resistivity, and the adhesion on the surface of the titanium oxide particles of the conductive composite particles prepared in Comparative Example 1. Show. Table 3 shows the results of X-ray diffraction of the conductive composite particles produced in Comparative Example 1.

〔比較例２の結果〕
　表２に、比較例１で作製した導電性複合粒子の酸化チタン粒子の表面での酸化錫微粒子の状態、酸化錫微粒子層の状態、ＢＥＴ比表面積、圧粉体抵抗率、密着性の結果を示す。また、表３に、比較例２で作製した導電性複合粒子のＸ線回折の結果を示す。 [Results of Comparative Example 2]
Table 2 shows the results of the state of the tin oxide fine particles, the state of the tin oxide fine particle layer, the BET specific surface area, the green compact resistivity, and the adhesion on the surface of the titanium oxide particles of the conductive composite particles prepared in Comparative Example 1. Show. Table 3 shows the results of X-ray diffraction of the conductive composite particles produced in Comparative Example 2.

〔比較例３の結果〕
　比較例３で作製した導電性複合粒子の高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子との界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタン粒子表面とのなす角度の絶対値が１０°以内である、すなわち酸化チタン粒子表面と平行な酸化チタンの格子像の存在を、酸化チタン粒子と酸化錫微粒子界面から４～８層目の全ての酸化チタンの格子像について確認した。また、比較例３で作製した導電性複合粒子の高分解能透過型電子顕微鏡像中で、酸化チタン粒子と酸化錫微粒子の界面の中心から、界面と平行な幅：５０ｎｍ、厚さ：５ｎｍの領域内で、酸化チタンの格子像とのなす角度の絶対値が１０°以下である、すなわち酸化チタンの格子像に平行な酸化錫の格子像の存在を、酸化チタン粒子と酸化錫微粒子界面から４～８層目の全ての酸化錫の格子像について確認した。表２に、比較例３で作製した導電性複合粒子の〔（Ｌｓ／Ｌｔ）×１００〕、酸化チタン粒子の表面での酸化錫微粒子の状態、酸化錫微粒子層の状態、ＢＥＴ比表面積、圧粉体抵抗率、密着性の結果を示す。また、表３に、比較例３で作製した導電性複合粒子のＸ線回折の結果を示す。 [Results of Comparative Example 3]
In the high-resolution transmission electron microscope image of the conductive composite particles produced in Comparative Example 3, from the center of the interface between the titanium oxide particles and the tin oxide fine particles, the width parallel to the interface: 50 nm and the thickness: 5 nm Thus, the absolute value of the angle formed with the surface of the titanium oxide particles is within 10 °, that is, the presence of a lattice image of titanium oxide parallel to the surface of the titanium oxide particles is 4 to 8 layers from the interface between the titanium oxide particles and the tin oxide fine particles. All the lattice images of titanium oxide in the eye were confirmed. Further, in the high-resolution transmission electron microscope image of the conductive composite particles produced in Comparative Example 3, a region parallel to the interface and having a width of 50 nm and a thickness of 5 nm from the center of the interface between the titanium oxide particles and the tin oxide fine particles. Among them, the absolute value of the angle formed with the lattice image of titanium oxide is 10 ° or less, that is, the presence of the lattice image of tin oxide parallel to the lattice image of titanium oxide is 4 from the interface between the titanium oxide particles and the tin oxide fine particles. The lattice images of all the tin oxides in the eighth to eighth layers were confirmed. Table 2 shows [(Ls / Lt) × 100] of the conductive composite particles prepared in Comparative Example 3, the state of the tin oxide fine particles on the surface of the titanium oxide particles, the state of the tin oxide fine particle layer, the BET specific surface area, the pressure. The results of powder resistivity and adhesion are shown. Table 3 shows the results of X-ray diffraction of the conductive composite particles produced in Comparative Example 3.

〔参考例１と２の結果〕
　表２に、参考例１の酸化チタン粒子のＢＥＴ比表面積と、参考例２の酸化錫粒子のＢＥＴ比表面積、圧粉体抵抗率を示す。なお、参考例１の圧粉体抵抗率は、粉体抵抗測定システムの測定範囲外であった。 [Results of Reference Examples 1 and 2]
Table 2 shows the BET specific surface area of the titanium oxide particles of Reference Example 1, the BET specific surface area of the tin oxide particles of Reference Example 2, and the green compact resistivity. The green compact resistivity in Reference Example 1 was outside the measurement range of the powder resistance measurement system.

　表２から明らかなように、実施例１～３は、高分解能透過型電子顕微鏡像において、酸化チタン粒子表面に平行な酸化チタンの格子像に対する、上記酸化チタンの格子像に高分解能透過型電子顕微鏡像で平行な酸化錫の格子像の長さの割合〔（Ｌｓ／Ｌｔ）×１００〕が、８０％以上であり、酸化錫微粒子層と酸化チタン粒子との密着性が高かった。また、酸化錫微粒子層が多孔質であるため、ＢＥＴ比表面積が非常に大きく、圧粉体抵抗率が低く、高導電性であった。したがって、実施例１～３で作製した導電性複合粒子は、いずれも、白金ナノ粒子触媒を担持するための担体として適していることがわかった。 As is apparent from Table 2, Examples 1 to 3 show high resolution transmission electron images in the lattice image of titanium oxide in contrast to the lattice image of titanium oxide parallel to the surface of the titanium oxide particles in high resolution transmission electron microscope images. The ratio of the length of the lattice image of tin oxide parallel to the microscopic image [(Ls / Lt) × 100] was 80% or more, and the adhesion between the tin oxide fine particle layer and the titanium oxide particles was high. Moreover, since the tin oxide fine particle layer was porous, the BET specific surface area was very large, the green compact resistivity was low, and the conductivity was high. Therefore, it was found that any of the conductive composite particles produced in Examples 1 to 3 was suitable as a support for supporting the platinum nanoparticle catalyst.

　これに対して、酸洗浄をしていない酸化チタン粒子を用い、シランカップリング剤を含有する酸化チタン粒子含有分散液を使用した比較例１では、高分解能透過型電子顕微鏡像において、酸化チタン粒子表面に対して平行な酸化チタンの格子像に対して、酸化錫の格子像が平行ではなく、密着性が良くなかった。また、酸洗浄をしていない酸化チタン粒子を使用した比較例２では、多孔質ではない膜状の酸化錫微粒子が酸化チタン粒子から剥離していた。比較例３では、高分解能透過型電子顕微鏡像において、酸化チタン粒子表面に平行な酸化チタンの格子像の長さに対して、上記酸化チタンの格子像に平行な酸化錫の格子像の長さが短く、酸化錫微粒子層と酸化チタン粒子との密着性が良くなかった。 On the other hand, in the comparative example 1 using the titanium oxide particle-containing dispersion containing the silane coupling agent using the titanium oxide particles that have not been subjected to acid cleaning, the titanium oxide particles in the high-resolution transmission electron microscope image The lattice image of tin oxide was not parallel to the lattice image of titanium oxide parallel to the surface, and adhesion was not good. Moreover, in the comparative example 2 using the titanium oxide particle which was not acid-washed, the film-form tin oxide fine particle which is not porous peeled from the titanium oxide particle. In Comparative Example 3, in the high-resolution transmission electron microscope image, the length of the tin oxide lattice image parallel to the titanium oxide lattice image is longer than the length of the titanium oxide lattice image parallel to the titanium oxide particle surface. And the adhesion between the tin oxide fine particle layer and the titanium oxide particles was not good.

　酸化チタン粒子を用いた参考例１は、導電性がなかった。酸化錫微粒子を用いた参考例２では、凝集が激しく、ハンドリング性が悪かった。したがって、比較例１～３、参考例１と２は、いずれも白金ナノ粒子触媒を担持するための担体として適していないことがわかった。 Reference Example 1 using titanium oxide particles had no conductivity. In Reference Example 2 using tin oxide fine particles, aggregation was severe and handling properties were poor. Therefore, it was found that Comparative Examples 1 to 3 and Reference Examples 1 and 2 are not suitable as carriers for supporting the platinum nanoparticle catalyst.

　本発明の導電性複合粒子では、酸化チタン粉末との密着性が高く、且つ比表面積が大きい酸化錫微粒子層が、酸化チタン粒子の表面上に形成されている。また、本発明の導電性複合粒子は導電性が高い。このため、本発明の導電性複合粒子は白金ナノ触媒の担体に好適である。
　また、本発明の燃料電池の電極触媒層用組成物、燃料電池の電極触媒層によれば、信頼性の高い燃料電池を形成できる。 In the conductive composite particles of the present invention, a tin oxide fine particle layer having high adhesion to the titanium oxide powder and a large specific surface area is formed on the surface of the titanium oxide particles. Moreover, the electroconductive composite particle of this invention has high electroconductivity. For this reason, the electroconductive composite particle of this invention is suitable for the support | carrier of a platinum nano catalyst.
Moreover, according to the composition for an electrode catalyst layer of a fuel cell and the electrode catalyst layer of a fuel cell of the present invention, a highly reliable fuel cell can be formed.

　　１　　燃料電池
　　１０　燃料極
　　１１　燃料極触媒層
　　１２　多孔質支持層
　　２０　電解質膜
　　３０　空気極
　　３１　空気極触媒層
　　３２　多孔質支持層
　　４　　導電性複合粒子
　　５　　酸化チタン粒子
　　６　　酸化錫微粒子層 DESCRIPTION OF SYMBOLS 1 Fuel cell 10 Fuel electrode 11 Fuel electrode catalyst layer 12 Porous support layer 20 Electrolyte membrane 30 Air electrode 31 Air electrode catalyst layer 32 Porous support layer 4 Conductive composite particle 5 Titanium oxide particle 6 Tin oxide fine particle layer

Claims

　酸化チタン粒子の表面が、多孔質の酸化錫微粒子層で被覆された導電性複合粒子であって、
　高分解能透過型電子顕微鏡像において、前記酸化チタン粒子の表面に平行な酸化チタンの格子像の長さに対して、前記酸化チタンの格子像に平行な酸化錫の格子像の長さが、８０％以上であることを特徴とする、導電性複合粒子。 The surface of the titanium oxide particles is a conductive composite particle coated with a porous tin oxide fine particle layer,
In the high-resolution transmission electron microscope image, the length of the lattice image of tin oxide parallel to the lattice image of the titanium oxide is 80 with respect to the length of the lattice image of titanium oxide parallel to the surface of the titanium oxide particles. %. Conductive composite particles characterized by being at least%.
　前記酸化チタンがルチル型の結晶構造を含み、前記酸化錫がルチル型の結晶構造を含み、
　前記酸化チタンの前記ルチル型の結晶構造の（１１０）面と、前記酸化錫の前記ルチル型の結晶構造の（１１０）面とが、電子線回折図形において平行である、請求項１記載の導電性複合粒子。 The titanium oxide includes a rutile-type crystal structure, and the tin oxide includes a rutile-type crystal structure;
The conductivity according to claim 1, wherein the (110) plane of the rutile crystal structure of the titanium oxide and the (110) plane of the rutile crystal structure of the tin oxide are parallel in the electron diffraction pattern. Composite particles.
　請求項１または２記載の導電性複合粒子と、分散媒とを含有する、燃料電池の電極触媒層用組成物。 A composition for an electrode catalyst layer of a fuel cell, comprising the conductive composite particles according to claim 1 or 2 and a dispersion medium.
　請求項１または２記載の導電性複合粒子を含有する、燃料電池の電極触媒層。 A fuel cell electrode catalyst layer comprising the conductive composite particles according to claim 1.
　請求項４記載の燃料電池の電極触媒層を備える、燃料電池。

A fuel cell comprising the electrode catalyst layer of the fuel cell according to claim 4.