JPS61205622A - Production of electrically conductive fine powder of tin oxide - Google Patents

Abstract

PURPOSE:To produce fine powder of tin oxide having high electrical conductivity and transparency, by dissolving metallic Sn and Sb in a mixture of nitric acid and hydrochloric acid, adding ammonia water to the solution, and disintegrating and calcining the produced colloid. CONSTITUTION:Metallic Sn and 2.0-15.0wt% metallic Sb and Sb compound (based on the Sn) are dissolved in an aqueous solution of a mixture of nitric acid and hydrochloric acid to obtain a transparent solution of stannic acid. The pH of the stannic acid solution is raised to >=3 by the addition of ammonia water. The produced colloid of tin hydrate is separated from the liquid, and dried. The secondary agglomerate of the colloidal powder is disintegrated taking advantage of the decomposition of NH4NO3, and the product is calcined by conventional method. Electrically conductive fine powder of tin oxide having excellent dispersibility can be produced by this process at a low cost.

Description

【発明の詳細な説明】 く技術分野〉 本発明は、白色から淡い青色に色調を有すると共に、良
好な電導性を有し、特にプラスチックやシリコンゴムな
ど（以下これらを総称してプラスチックと略記する）に
塗布または混入して、これらに電導性を付与する目的で
使用するのに適した酸化錫系電導性微粉末の製造法に関
する。[Detailed Description of the Invention] Technical Field> The present invention has a color tone ranging from white to pale blue and has good electrical conductivity, and is particularly applicable to plastics, silicone rubber, etc. (hereinafter collectively abbreviated as plastics). This invention relates to a method for producing a tin oxide-based electrically conductive fine powder suitable for use in coating or mixing with other materials to impart electrical conductivity to them.

〈従来技術〉 従来から、金属粉末やカーボン粉末などの電導性粉末を
プラスチックに塗布または混入することによって、これ
に電導性を付与することが行われているが、このように
プラスチックに金属粉末やカーボン粉末を混入すると、
プラスチック自体のもつ色調が損なわれて灰色または黒
色がかった色調をもつようになるため、プラスチックの
色調はかなり制限されたものになり、さらにプラスチッ
クが本来具備する透明性も損なわれるようになることか
ら、その用途は限られたものになる。<Prior art> Conventionally, conductivity has been imparted to plastics by applying or mixing conductive powders such as metal powders or carbon powders to plastics. When carbon powder is mixed in,
The color tone of the plastic itself is lost, giving it a gray or blackish tone, making the color tone of the plastic quite limited, and furthermore, the inherent transparency of the plastic is also lost. , its use will be limited.

したがって、近年１表示用電極、保護膜、静電防止用フ
ィルム、さらに透明発熱体などとして多く用いられるよ
うになってきた電導性と透明性が要求されるプラスチッ
ク塗膜、シート、板等には、プラスチック中に混入する
ことによってプラスチックのもつ透明性を損なうことな
く、これに良好な電導性を付与することのできる電導性
微粉末について、種々の研究が行われている。Therefore, plastic coatings, sheets, plates, etc. that require conductivity and transparency, which have recently been widely used as display electrodes, protective films, antistatic films, and transparent heating elements, etc. Various studies have been conducted on conductive fine powders that can be mixed into plastics to impart good conductivity to the plastics without impairing their transparency.

これらの研究の中で酸化錫に、酸化アンチモン、酸化イ
ンジウム、酸化ガリウム、酸化ビスマス、酸化ニオブ、
酸化タンタル等を固溶させたものは電導性に優れていて
しかも白色から淡い青色の微粉末をうることができるの
で有用である。In these studies, tin oxide, antimony oxide, indium oxide, gallium oxide, bismuth oxide, niobium oxide,
A solid solution containing tantalum oxide or the like is useful because it has excellent conductivity and can produce a white to pale blue fine powder.

酸化錫固溶体の透明性と電導性は主として粉末の焼結性
によって左右されるので、表面エネルギーが高く分散性
に優れた微細粉体を得るために多くの製造法が研究され
てきた。これらの製造法は、太きく１）乾式法と２）湿
式法、すなわちｌ）酸化スズと酸化アンチモンの粉末を
調製して混和し焼結する方法と、２）塩化スズおよび塩
化アンチモンの溶液を中和あるいは加水分解して酸化ス
ズと酸化アンチモンをコロイド状で共沈させ、このコロ
イド状共沈物を焼成する方法とにわけられる。Since the transparency and conductivity of tin oxide solid solutions depend mainly on the sinterability of the powder, many manufacturing methods have been investigated to obtain fine powders with high surface energy and excellent dispersibility. These manufacturing methods are broadly divided into 1) dry method and 2) wet method, namely l) method of preparing powders of tin oxide and antimony oxide, mixing and sintering, and 2) method of preparing a solution of tin chloride and antimony chloride. There are two methods: neutralization or hydrolysis to co-precipitate tin oxide and antimony oxide in colloidal form, and then sintering this colloidal coprecipitate.

湿式法の中で特に加熱水中に、アルコール、塩酸水溶液
、およびアセトンのうちの１種または２種以上の混合液
に所定の量の塩化スズと塩化アンチモンとを溶解したも
のからなる溶液を加えて酸化スズ微粉末を析出生成させ
る製造法（特開昭５６−１５６６０６号）が知られてい
る。In the wet method, in particular, a solution consisting of a predetermined amount of tin chloride and antimony chloride dissolved in a mixture of one or more of alcohol, aqueous hydrochloric acid, and acetone is added to heated water. A manufacturing method (JP-A-56-156606) is known in which fine tin oxide powder is precipitated.

しかしながら、この製造法による場合、塩化錫を多量に
用いるので、原料コストが高くなり、製品価格が高いと
いう問題がある。そのため原料コストが安く、粉体の抵
抗が小さく、粒子径のより小さい製造法の開発が望まれ
ている。However, in this production method, since a large amount of tin chloride is used, there is a problem that the raw material cost is high and the product price is high. Therefore, it is desired to develop a manufacturing method that has low raw material costs, low powder resistance, and smaller particle diameters.

さらに、溶液から微粉末を析出精製させる湿式法による
製法では、微粉末の分離精製工程が長時間を要したり精
製不充分だったりして製品の品質を下げる場合が多く、
分離精製の容易な製造法が求められている。Furthermore, in wet manufacturing methods in which fine powder is precipitated and purified from a solution, the separation and purification process of the fine powder often takes a long time or is insufficiently purified, resulting in a reduction in product quality.
There is a need for a manufacturing method that facilitates separation and purification.

〈発明の目的〉 本発明の目的は、このような点を改善し、塩化錫を用い
ることなく金属錫を原料として用い、原料コストが安く
、電導性が良好で、透明性のよい５ｍ化錫系電導性微粉
末の湿式法による製造法であって１分離精製の容易な製
造法を提供することにある。<Objective of the Invention> The object of the present invention is to improve the above-mentioned points and to produce 5m tin chloride which uses metallic tin as a raw material without using tin chloride, has low raw material cost, good conductivity, and good transparency. The object of the present invention is to provide a method for producing conductive fine powder by a wet method, which is easy to perform one separation and purification.

〈発明の簡単な説明〉 このような目的は、下記の本発明により達成することが
できる。<Brief Description of the Invention> Such objects can be achieved by the present invention described below.

すなわち、本発明は金属錫と金属錫に対し２．０〜１５
．０重量％の金属アンチモンおよび／またはアンチモン
化合物とを、硝酸および塩酸を含む混酸に溶解して、錫
酸溶液を得、この錫酸溶液にアンモニア水を加え、ｐＨ
３以上として錫水和物コロイドを生成し、得られたコロ
イドを分離し、これを乾燥させてアンモニア水添加によ
り生じたＮＨ４ＮＯ３の分解を利用してコロイド粉末の
二次凝集体を解砕した後、焼成することを特徴とする酸
化錫系電導性微粉末の製造法である。That is, in the present invention, metal tin and metal tin have 2.0 to 15
．． 0% by weight of metallic antimony and/or antimony compound is dissolved in a mixed acid containing nitric acid and hydrochloric acid to obtain a stannic acid solution, and aqueous ammonia is added to this stannic acid solution to adjust the pH.
After producing a tin hydrate colloid as 3 or more, separating the obtained colloid, drying it, and disintegrating the secondary aggregates of the colloid powder using the decomposition of NH4NO3 generated by adding ammonia water. This is a method for producing a tin oxide-based conductive fine powder, which is characterized by firing.

〈発明の具体的構成〉 本発明の酸化錫系電導性微粉末の製造法について以下に
詳細に説明する。<Specific Structure of the Invention> The method for producing the tin oxide-based conductive fine powder of the present invention will be described in detail below.

塗布型透明電導性膜を作るための微細な酸化錫系電導性
微粉末の重要な条件は、透明であることと粉体の抵抗が
低いことである。透明であるためには粒径が可視光の波
長以下、すなわち約０．４〜０．３ル■以下であり、特
定の光吸収がないことが必要となる。アンチモンを含む
二酸化錫は、赤外吸収はあるが、この目的に適している
。The important conditions for fine tin oxide-based conductive powder for making a coated transparent conductive film are that it be transparent and have low resistance. In order to be transparent, the particle size must be less than the wavelength of visible light, that is, approximately 0.4 to 0.3 l, and there must be no specific light absorption. Tin dioxide, which contains antimony, is suitable for this purpose despite its infrared absorption.

（１）まず、金属錫を用いて錫醸液を調製する。(1) First, a tin brewing liquid is prepared using metal tin.

金属Ｓｎ粒と金属Ｓｎに対し２．０−１５重量％の金属
ｓｂおよび／またはｓｂ化合物とを、ＨＮＯ３と、ＨＮ
Ｏ３に対して１０〜５０重量％のＨＣ見との混酸水溶液
に、撹拌しながら徐々に加えて溶解し、添加後さらに撹
拌を続けると透明な錫酸溶液が得られる０反応温度は２
０〜７０℃に保つ、　　ＨＮＯ３濃度は２０重量％以上
とする。Metal Sn grains and 2.0-15% by weight of metal sb and/or sb compound relative to metal Sn are combined with HNO3 and HN
Gradually add and dissolve in a mixed acid solution containing 10 to 50% by weight of HC based on O3 while stirring, and continue stirring after addition to obtain a transparent stannic acid solution.The reaction temperature is 2.
Maintain the temperature between 0 and 70°C, and keep the HNO3 concentration at least 20% by weight.

ｓｂが２．０重量％未満では得られる微粉末の電導性が
小さく、１５．０重量％を越えると着色が大となり、透
明膜が得難い。If sb is less than 2.0% by weight, the resulting fine powder will have low electrical conductivity, and if it exceeds 15.0% by weight, coloring will be large and it will be difficult to obtain a transparent film.

ｓｂは金属ｓｂを用いるが、使用量が少ないので。Metal sb is used for sb, but the amount used is small.

塩化アンチモン等のアンチモン化合物を用いてもよいし
、金属ｓｂとｓｂ化合物の混合物を用いてもよい。An antimony compound such as antimony chloride may be used, or a mixture of metal sb and sb compound may be used.

ＨＣＩは金属Ｓｎ粒の溶解力を強める作用をする。HCI acts to strengthen the dissolving power of metal Sn particles.

Ｈ（４と　ＨＮＯ３の混酸とすることによってＨＮＯ３
濃度が小さくても金属Ｓｎを溶解することができる。By making a mixed acid of H(4 and HNO3), HNO3
Even if the concentration is small, metal Sn can be dissolved.

Ｈａ文を混合しない）ＩＮＯ３単独では透明な錫酸液を
作るのは困難である。ＨＣｆＬは、また生成した錫酸溶
液の粘度を下げ、温湯酸液を可能とする働きをする。Ｈ
ａ文が１０重量％より少ないと以上の効果が小となり、
５０重量％を越えると、最終製品の酸化錫微粉−末にＨ
ａ文が残留し、二次凝集が大となってしまう。It is difficult to make a transparent tin acid solution using INO3 alone (without mixing Ha). HCfL also serves to reduce the viscosity of the produced stannic acid solution, making it possible to form a hot water acid solution. H
If the amount of a sentence is less than 10% by weight, the above effect will be small,
If the amount exceeds 50% by weight, H
The a sentence remains and secondary aggregation becomes large.

反応温度が２０℃より低いと１反応速度が小さくなり実
際的でない、７０℃を越えると不溶性の５ｎ０２が生成
し、透明な錫酸溶液が得られない。If the reaction temperature is lower than 20°C, the reaction rate will be too low to be practical, and if it exceeds 70°C, insoluble 5n02 will be produced, making it impossible to obtain a transparent stannic acid solution.

ＨＮＯ３濃度が２０重量％より小さいと反応速度が小さ
い、上限は特にないが、６０重量％を越えるものは特に
利点もなく、実際的でない、このため市販の１．３８　
（比重）　　ＨＮＯ３の使用でよく、１．４２ＨＮＯ３
は取扱いが危険であるため使用する必要はない。If the HNO3 concentration is less than 20% by weight, the reaction rate is low.There is no particular upper limit, but if it exceeds 60% by weight, there is no particular advantage and it is not practical.For this reason, commercially available 1.38
(Specific gravity) HNO3 can be used, 1.42HNO3
There is no need to use it as it is dangerous to handle.

ＨＮＯ３濃度、ｎｃｉ濃度および生成錫酸濃度は上記の
範囲内で適当に組合せればよいが、一般に温湯酸液を得
るにはＨＮＯ３濃度を大とし、錫酸液の粘度を下げるた
めにＨＣＩ濃度も大とする。この際反応温度は低くなる
。The HNO3 concentration, nci concentration, and produced stannic acid concentration may be appropriately combined within the above ranges, but in general, the HNO3 concentration is increased to obtain a hot water acid solution, and the HCI concentration is also increased to lower the viscosity of the stannic acid solution. Make it large. At this time, the reaction temperature becomes low.

（２）次に上記のｆ！酸溶液に、アンモニア水を加える
。(2) Next, the above f! Add aqueous ammonia to the acid solution.

得られた錫酸溶液とＮＨ，ＯＨ水を撹拌しながら混合し
てｐＨ３，０以上として湯水和物コロイドを生成する。The obtained stannic acid solution and NH,OH water are mixed with stirring to adjust the pH to 3.0 or higher to produce a hot water hydrate colloid.

　ｐ）！　３．０より少ないと、錫木和物コロイドの生
成が不充分で、濾過性も悪くなる。p)! If it is less than 3.0, the formation of tin wood colloid will be insufficient and the filterability will be poor.

混合の際の混合順序、混合速度、温度、ＮＨ４０Ｈ水濃
度等は生成物の性状にそれ程大きな効果を持たないので
、錫酸の濃度なども考え適切な組合せで行う、一般的に
は純水を加えて加水分解する場合に比してコロイド生成
のための液の液量は少なくしてすむ。The mixing order, mixing speed, temperature, NH40H water concentration, etc. during mixing do not have much effect on the properties of the product, so consider the concentration of stannic acid and perform the appropriate combination. Generally, pure water is used. In addition, the amount of liquid for colloid production can be smaller than in the case of hydrolysis.

アンモニア水以外のＮａＯＨ水等では次の解砕φ乾燥・
焼成工程を行ってもＨａ等が製品微粉末に残存してしま
うため不適当である。For NaOH water other than ammonia water, the following crushing φ drying and
This is inappropriate because Ha and the like remain in the product fine powder even after the firing process.

（３）生成したコロイドの固液分離を行う。(3) Perform solid-liquid separation of the generated colloid.

本発明ではアンモニア水添加工程で生成したＮＨ４　Ｎ
Ｏ３の解砕を利用するので洗浄は必要でないか或いは５
ｎ０２に対して最低１０重量％のＮＨ４ＮＯ３が残るよ
うに洗浄を行う、１０％より少ないと二次凝集解決の効
果が少ないからである。In the present invention, NH4N generated in the ammonia water addition step
Since it utilizes O3 disintegration, cleaning is not necessary or 5
Washing is performed so that at least 10% by weight of NH4NO3 remains based on n02, because if it is less than 10%, the effect of resolving secondary aggregation will be small.

洗浄、分離の装置、方法に付いては通常の水洗、濾過等
を行う。Regarding cleaning and separation equipment and methods, use normal water washing, filtration, etc.

ＮＨ４ＮＯ３が１０重量％以上残っているので濾過が容
易であり短時間で行うことができる。Since 10% by weight or more of NH4NO3 remains, filtration is easy and can be carried out in a short time.

（４）次いで、（３）で得られた酸化錫系微粉末を解砕
乾燥し、結晶性を向上させる目的で空気中で焼成する。(4) Next, the tin oxide-based fine powder obtained in (3) is crushed and dried, and fired in air for the purpose of improving crystallinity.

分離したＮＨ４ＮＯ３を含む漏水和物のケークをＮＨ４
ＮＯ３の分解温度である２２０℃以上で加熱乾燥し、　
ＮＨ４ＮＯ３の分解を行った後、焼成を行う。The leakage hydrate cake containing separated NH4NO3 is converted into NH4
Heat and dry at 220°C or higher, which is the decomposition temperature of NO3,
After decomposing NH4NO3, calcination is performed.

ＮＨ４ＮＯ３の分解は数分で急速におこる。乾燥温度は
２２０℃〜３００℃とする。２２０℃より低いと、ＮＨ
４ＮＯ３の分解が起こらず、３００℃を越えると、分解
に伴なう５ｎ０２粉末の飛散が多くなる。このＮＨ４Ｎ
Ｏ３の分解工程を行うことにより。Decomposition of NH4NO3 occurs rapidly within minutes. The drying temperature is 220°C to 300°C. If it is lower than 220℃, NH
If the temperature exceeds 300° C. without decomposition of 4NO3, the scattering of 5n02 powder due to decomposition increases. This NH4N
By performing an O3 decomposition step.

５ｎ０２粉末の二次凝集を解砕して、分散性のよい５ｎ
０２　微粉末を得る効果がある。By breaking up the secondary agglomeration of 5n02 powder, 5n with good dispersibility is produced.
02 Effective in obtaining fine powder.

最終５ｎ０２微粉末にはＮＨ４８０３はほとんど残らず
、洗浄した場合と同程度である。Almost no NH4803 remained in the final 5n02 fine powder, and it was the same level as when washed.

乾燥は熱風乾燥等の通常の方法が用いられる。For drying, a conventional method such as hot air drying is used.

乾燥時間は用いる方法温度により異なるが２〜３時間が
好ましい。The drying time varies depending on the method temperature used, but is preferably 2 to 3 hours.

焼成は通常の焼成炉を用い、温度５００℃〜１０００℃
、時間５ｍ１ｎ　〜４０ｈｒとする。低温では長時間焼
成が必要である。５００℃より低いと、不純物（Ｃ１２
、ＮＯｘ等）の揮発不充分で二次凝集が多くなり、１０
００℃をこえると、−次粒子の成長が起こり、粒子の径
大化が起こる。好ましくは、８００℃Ｘ１ｈｒ、６００
℃Ｘ２０ｈｒが良い。Firing is done using a regular firing furnace at a temperature of 500℃ to 1000℃.
, the time is 5 m1n to 40 hr. Long firing times are required at low temperatures. If it is lower than 500℃, impurities (C12
, NOx, etc.), secondary aggregation increases, and 10
When the temperature exceeds 00°C, the growth of secondary particles occurs and the particles become larger in diameter. Preferably, 800℃×1hr, 600℃
℃×20hr is good.

〈実施例〉 ６０％　ＨＮＯ３１１０ｍｌ　と３５％ＨＣ１２５ｍＪ
１とＨ２Ｈ２Ｏ２０Ｏの混酸溶液を撹拌しながらＳｎ粒
８０ｇ、Ｓｂ粉末６ｇを約２ｈｒかけて添加した。金属
の添加が終った後、更に撹拌を３ｈｒ行って透明なｉ酸
溶液が得られた。この間１反応容器ｌよ４５°Ｃに調節
された水槽中に保持されていた。<Example> 3110 ml of 60% HNO and 125 mJ of 35% HC
80 g of Sn particles and 6 g of Sb powder were added to a mixed acid solution of 1 and H2H2O20O over about 2 hours while stirring. After the metal addition was completed, stirring was continued for 3 hours to obtain a clear i-acid solution. During this time, one reaction vessel was kept in a water bath adjusted to 45°C.

得られた酸性の錫酸溶液に２９％アンモニア水１００　
　膿文とＨ２Ｏ１３０＋ｓ文の混合液を撹拌しながら加
えた。この時スラリー液のｐＨは８．８であった。Add 100% 29% ammonia water to the resulting acidic stannic acid solution.
A mixture of P. aeruginosa and H2O130+s was added with stirring. At this time, the pH of the slurry liquid was 8.8.

スラリの分離は遠心症過器で行い、得られたケークを２
５０℃の通風乾燥器でそのまま乾燥し、ＮＨ４８０３の
分解を行った後、乾燥器より取出した。乾燥には約Ｚｈ
ｒかかり、乾燥終了後乾燥物の温度が上昇し、分解温度
に達して急激なＮＨ４ＮＯ３の分解反応が起こった。The slurry was separated using a centrifuge, and the resulting cake was divided into two
After drying as it was in a ventilation dryer at 50°C to decompose NH4803, it was taken out from the dryer. Approximately Zh for drying
After the drying was completed, the temperature of the dried product rose and reached the decomposition temperature, causing a rapid decomposition reaction of NH4NO3.

得られた粉末を８００℃の電気炉中でｌｈｒ加熱して電
導性５ｎ０２微粉末を得た。The obtained powder was heated for 1 hour in an electric furnace at 800° C. to obtain a conductive 5n02 fine powder.

得られた微粉末は比抵抗０．６ΩＩＩｃ■、ＢＥＴ法で
測定した比表面積４５■２１ｇ、電子顕微鏡で見た一次
粒径は約０．０３ｇｍであった０分散性を見るため、一
定の条件で水に分散した後、０．３ＪＬｓ以上の二次粒
径を持つ粒子を遠心分離し、残った液中に分散している
粒子の％を求めると７３％であった。The obtained fine powder had a specific resistance of 0.6 Ω IIc, a specific surface area of 45 21 g as measured by the BET method, and a primary particle size of about 0.03 gm as measured by an electron microscope. After being dispersed in water, the particles having a secondary particle size of 0.3 JLs or more were centrifuged, and the percentage of particles dispersed in the remaining liquid was determined to be 73%.

〈発明の効果〉 本発明の酸化錫系電導性微粉末の製造法は。<Effect of the invention> The method for producing the tin oxide-based conductive fine powder of the present invention is as follows.

塩化錫等の錫化合物を用いずに、金属錫を直接ＨＮＯ３
とＨＣ文の混酸に溶解する。そのため安価に酸化錫系電
導性微粉末を製造することができる。Metallic tin is directly converted into HNO3 without using tin compounds such as tin chloride.
Dissolves in a mixed acid of HC and HC. Therefore, tin oxide-based conductive fine powder can be produced at low cost.

また、ＨＣ９，との混酸とすることにより、　）１８０
３の溶解力を強め、結果として使用するｌＮＯ３５度を
下げることができるので、耐酸設備上の経費が少なくて
すみ安全面でも有利であり、）１８０３使用量が少なく
なるので製品価格が安価となる。In addition, by making it a mixed acid with HC9, )180
It strengthens the dissolving power of 1803 and as a result lowers the 1NO35 degrees used, which reduces the cost of acid-resistant equipment and is advantageous in terms of safety.) Since the amount of 1803 used decreases, the product price becomes cheaper. .

また、アンモニア水添加により生じたＮＨ４ＮＯ３の熱
分解によりコロイド粉末の凝集を防ぐので微細な粉末が
得られ、不純物も残存しない。Furthermore, since agglomeration of colloidal powder is prevented by thermal decomposition of NH4NO3 generated by addition of ammonia water, fine powder is obtained and no impurities remain.

さらに錫酸溶液から析出する酸化錫系微粉末の洗浄工程
がほとんど必要なく、濾過工程も短時間で行うことがで
き、えられる酸化錫系微粉末の分散性も良好である。Further, there is almost no need for a washing process for the tin oxide-based fine powder precipitated from the stannic acid solution, a filtration process can be carried out in a short time, and the resulting tin oxide-based fine powder has good dispersibility.

Claims (1)

【特許請求の範囲】[Claims] （１）金属錫と金属錫に対し２．０〜１５．０重量％の
金属アンチモンおよび／またはアンチモン化合物とを、
硝酸および塩酸を含む混酸に溶解して、錫酸溶液を得、
この錫酸溶液にアンモニア水を加え、ｐＨ３以上として
錫水和物コロイドを生成し、得られたコロイドを分離し
、これを乾燥させてアンモニア水添加により生じたＮＨ
＿４ＮＯ＿３の分解を利用してコロイド粉末の２次凝集
体を解砕した後、焼成することを特徴とする酸化錫系電
導性微粉末の製造法。(1) Metallic tin and 2.0 to 15.0% by weight of metal antimony and/or antimony compound relative to metal tin,
Dissolve in a mixed acid containing nitric acid and hydrochloric acid to obtain a stannic acid solution,
Ammonia water is added to this stannic acid solution to raise the pH to 3 or higher to produce a tin hydrate colloid, the resulting colloid is separated, and it is dried to produce NH
A method for producing a tin oxide-based conductive fine powder, which comprises crushing secondary aggregates of colloidal powder using the decomposition of _4NO_3 and then firing.