JP3175212B2 - Method for reducing resistance of ITO powder - Google Patents
Method for reducing resistance of ITO powderInfo
- Publication number
- JP3175212B2 JP3175212B2 JP20633891A JP20633891A JP3175212B2 JP 3175212 B2 JP3175212 B2 JP 3175212B2 JP 20633891 A JP20633891 A JP 20633891A JP 20633891 A JP20633891 A JP 20633891A JP 3175212 B2 JP3175212 B2 JP 3175212B2
- Authority
- JP
- Japan
- Prior art keywords
- powder
- ito
- ito powder
- resistance
- film
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
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- Conductive Materials (AREA)
- Liquid Crystal (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、透明電極や帯電防止フ
ィルム等の低抵抗透明導電膜を塗布により形成するに使
用されるＩＴＯ粉末の低抵抗化処理方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reducing the resistance of an ITO powder used for forming a low-resistance transparent conductive film such as a transparent electrode or an antistatic film by coating.
【０００２】[0002]
【従来技術】最近、液晶ディスプレイやエレクトロルミ
ネッセンスディスプレイ等のフラットディスプレイが、
情報表示機器に多く使用されている。これらのディスプ
レイでは、表示素子の電極あるいは駆動回路の電極に透
明導電膜が使用されているが、この膜には、抵抗値が小
さく透明性が優れていることからＩＴＯ膜が適してい
る。このＩＴＯ膜を形成する方法として、ＩＴＯターゲ
ットをスパッタリングして基板上に成膜する方法がある
が、この方法は、装置が高価であり、大面積の加工に適
しておらず、また成膜後にエッチングによるパターン加
工が必要である等の問題を有している。そこで最近で
は、ＩＴＯペーストの塗布によるＩＴＯ膜の形成方法が
開発されつつある。この方法は、ＩＴＯ粉末と樹脂及び
溶剤を混合してペースト状とした後、該ペーストを基材
に印刷して乾燥することによりＩＴＯ膜の形成を行なう
ものである。この方法に使用するＩＴＯ粉末は、樹脂へ
の均一分散が容易であることに加えて、形成されるＩＴ
Ｏ膜の抵抗値を低くするために、その粉末自体の抵抗が
低いことが必要である。2. Description of the Related Art Recently, flat displays such as liquid crystal displays and electroluminescent displays have been developed.
It is widely used for information display devices. In these displays, a transparent conductive film is used for an electrode of a display element or an electrode of a driving circuit, and an ITO film is suitable for this film because of its small resistance and excellent transparency. As a method of forming the ITO film, there is a method of forming a film on a substrate by sputtering an ITO target. However, this method is expensive, and is not suitable for processing a large area. There is a problem that pattern processing by etching is required. Therefore, recently, a method of forming an ITO film by applying an ITO paste has been developed. In this method, an ITO film is formed by mixing an ITO powder, a resin, and a solvent to form a paste, printing the paste on a base material, and drying the paste. The ITO powder used in this method is not only easy to uniformly disperse in a resin, but also
In order to lower the resistance value of the O film, it is necessary that the resistance of the powder itself be low.
【０００３】[0003]
【発明が解決しようとする課題】然しながら、従来の塗
布用のＩＴＯ粉末は、超微粉で凝集体がなく分散性が良
好であるという点では満足し得るものの、その粉末自体
の抵抗値は高いという問題を有している。このため、従
来では、抵抗の高いＩＴＯ粉末を脱酸素処理し、酸素の
格子欠陥を生じさせることにより、該粉末を低抵抗化す
ることが行なわれていた。従来公知の上記低抵抗化処理
法としては、ＩＴＯ粉末をオクタノール、ブタノール等
の高沸点有機溶媒に浸漬し、不活性ガス雰囲気中で加熱
して脱酸素処理することにより低抵抗化を行なう方法が
知られているが、この方法では、有機溶媒が蒸発する際
にＩＴＯ粉末の凝集が生じ、これを粉砕しても凝集物を
完全に消失させることが困難であるという欠点を有して
いた。またＩＴＯ粉末を水素雰囲気または一酸化炭素雰
囲気等の還元性ガス雰囲気中で加熱することにより、脱
酸素処理を行ないＩＴＯ粉末を低抵抗化する方法も知ら
れている。しかし、水素は還元性が強いため、僅かな温
度上昇により還元が進行しすぎてＩＴＯ粉末の色が暗く
なったり、金属インジウムあるいは金属スズが析出して
しまうという問題がある。かかるＩＴＯ粉末を用いて膜
を形成した場合、その膜の透明性の低下は免れない。こ
のような水素雰囲気で処理を行なう場合には、厳格な温
度制御が必要となるのである。また一酸化炭素は人体に
有害で取扱いが困難であるという問題がある。従って本
発明の目的は、ＩＴＯ粉末の凝集を生じることなく、安
定に低抵抗化する処理方法を提供することにある。However, although the conventional ITO powder for coating is satisfactory in that it is an ultra-fine powder and has no agglomerates and good dispersibility, the resistance value of the powder itself is high. Have a problem. For this reason, conventionally, a high-resistance ITO powder has been subjected to deoxygenation treatment to generate oxygen lattice defects, thereby reducing the resistance of the powder. As a conventionally known low resistance treatment method, a method of immersing ITO powder in a high-boiling organic solvent such as octanol or butanol and heating in an inert gas atmosphere to perform a deoxygenation treatment is used to reduce the resistance. It is known, however, that this method has a disadvantage that when the organic solvent evaporates, agglomeration of the ITO powder occurs, and it is difficult to completely eliminate the agglomerate even if the powder is pulverized. A method is also known in which the ITO powder is heated in a reducing gas atmosphere such as a hydrogen atmosphere or a carbon monoxide atmosphere to perform a deoxygenation treatment to reduce the resistance of the ITO powder. However, since hydrogen has a strong reducing property, there is a problem that the reduction proceeds excessively due to a slight temperature rise, so that the color of the ITO powder becomes dark, or metal indium or metal tin is deposited. When a film is formed using such ITO powder, the transparency of the film is inevitably reduced. When processing is performed in such a hydrogen atmosphere, strict temperature control is required. In addition, there is a problem that carbon monoxide is harmful to the human body and difficult to handle. Accordingly, an object of the present invention is to provide a processing method for stably lowering resistance without causing aggregation of ITO powder.
【０００４】[0004]
【課題を解決するための手段】本発明によれば、ＩＴＯ
粉末を、アルコールガスを含有する不活性ガス雰囲気中
で加熱することを特徴とするＩＴＯ粉末の低抵抗化処理
方法が提供される。According to the present invention, an ITO is provided.
A method for reducing the resistance of an ITO powder, which comprises heating the powder in an inert gas atmosphere containing an alcohol gas, is provided.
【０００５】ＩＴＯ粉末 本発明において、処理すべきＩＴＯ粉末は塗布用のもの
であり、例えば、樹脂等との分散性を良好にするため
に、その平均粒径が 0.1μm 以下の範囲にある極めて微
細なものが使用される。その組成は、用途等によっても
異なるが、一般にインジウム含量が77〜81重量％及びス
ズ含量が１〜５重量％の範囲にある。またこのＩＴＯ粉
末は、通常、その抵抗値は高抵抗であり、10Ω・cm以上
の範囲にある。[0005] In ITO powder present invention, ITO powder to be treated is of the coating, for example, in order to improve the dispersibility of the resin or the like, extremely average particle size is in the range of 0.1μm Fine ones are used. The composition varies depending on the use and the like, but generally the indium content is in the range of 77 to 81% by weight and the tin content is in the range of 1 to 5% by weight. The ITO powder usually has a high resistance value, and is in a range of 10 Ω · cm or more.
【０００６】脱酸素処理 本発明においては、上記のＩＴＯ粉末をアルコールガス
を含有する不活性ガス雰囲気中で加熱することにより、
脱酸素が行なわれて酸素の格子欠陥が生じ、この結果と
して、該粉末の低抵抗化が行なわれる。[0006] In the deoxygenation present invention, by heating the above ITO powder in an inert gas atmosphere containing an alcohol gas,
Deoxygenation is performed to cause lattice defects of oxygen, and as a result, the resistance of the powder is reduced.
【０００７】上記処理に用いるアルコールガスは、還元
により脱酸素作用を示すものであり、かかるアルコール
ガスとしては、特に制限されないが、一般的には、揮発
性と価格の点から、メタノール、エタノール、プロパノ
ール等が好適であり、これらは１種単独で用いてもよい
し、２種以上を組み合わせて用いることもできる。アル
コールガスの不活性ガス中濃度は、50〜500 mg／Nlの範
囲とすることが 好適である。50mg／Nl未満では、脱酸
素に必要以上に時間がかかり、生産効率が低下し、また
500mg／Nlを超えると、脱酸素の速度が大きくなるため
に、終点のコントロールが困難となる。また不活性ガス
は、上記アルコールガスのキャリヤガスとして使用され
るものであり、窒素ガス、アルゴンガス等の任意の不活
性ガスを用いることができる。[0007] The alcohol gas used in the above treatment has a deoxidizing effect by reduction. Such alcohol gas is not particularly limited, but generally, methanol, ethanol, and the like are used in view of volatility and price. Propanol and the like are preferred, and these may be used alone or in combination of two or more. The concentration of the alcohol gas in the inert gas is preferably in the range of 50 to 500 mg / Nl. If it is less than 50 mg / Nl, it takes longer than necessary for deoxygenation, the production efficiency decreases, and
If it exceeds 500 mg / Nl, it becomes difficult to control the end point because the rate of deoxygenation increases. The inert gas is used as a carrier gas for the alcohol gas, and any inert gas such as a nitrogen gas and an argon gas can be used.
【０００８】本発明において、上記アルコールガス含有
不活性ガス雰囲気中での加熱は、通常、 200〜450 ℃、
特に 250〜350 ℃の範囲で行なうことが望ましい。 200
℃未満では、脱酸素を十分に行なうことが困難となり、
この結果として、目的とするＩＴＯ粉末の低抵抗化を達
成することが困難となる。また 450℃を超えると、ＩＴ
Ｏ粉末の凝集、焼結を生じるので望ましくない。In the present invention, the heating in the above-mentioned alcohol gas-containing inert gas atmosphere is usually performed at 200 to 450 ° C.
In particular, it is desirable to carry out at a temperature in the range of 250 to 350 ° C. 200
If the temperature is lower than ℃, it becomes difficult to sufficiently perform deoxygenation,
As a result, it is difficult to achieve the desired low resistance of the ITO powder. If the temperature exceeds 450 ° C, IT
This is undesirable because it causes aggregation and sintering of the O powder.
【０００９】かかる加熱によるＩＴＯ粉末の処理は、該
粉末の脱酸素が均一に進行するように攪拌しながら行な
うことが好適である。またこの加熱によって、ＩＴＯ粉
末の色が黄色から黄緑、青灰色と変化していく。ＩＴＯ
粉末が青灰色を呈した時点で処理の終点とみなす。それ
以上時間をかけて処理を行なったとしても、ＩＴＯ粉末
の抵抗値は低くならず、逆に、金属インジウムの析出を
生じる恐れがある。[0009] The treatment of the ITO powder by such heating is preferably carried out with stirring so that the deoxidization of the powder proceeds uniformly. Further, by this heating, the color of the ITO powder changes from yellow to yellow-green and blue-gray. ITO
The end point of the treatment is considered when the powder turns blue-grey. Even if the treatment is performed for a longer time, the resistance value of the ITO powder does not decrease, and conversely, metal indium may be deposited.
【００１０】上述した処理により、ＩＴＯ粉末の超微粉
状態を保持したまま、凝集体を生じることなく、例えば
加圧時比抵抗が0.01〜0.50Ω・cmの範囲に低抵抗化され
たＩＴＯ粉末が得られる。この粉末は、それ自体公知の
塗布手段により、低抵抗のＩＴＯ膜の形成に使用され
る。[0010] By the above-mentioned treatment, the ITO powder whose resistivity has been reduced to, for example, 0.01 to 0.50 Ω · cm without pressurizing while maintaining the ultrafine state of the ITO powder can be obtained. can get. This powder is used for forming a low-resistance ITO film by a coating means known per se.
【００１１】実施例１〜５ アルコキシド法により調製された凝集体がなく分散性の
良好なＩＴＯ粉末（平均粒径： 0.050μm ）を、２リッ
トルのセパラブルフラスコに入れ、マントルヒーターを
用いて加熱し且つ攪拌しながら、アルコールガスを含有
する窒素ガスを通じて脱酸素処理を行なった。この時の
処理条件を表１に示す。また処理前後のＩＴＯ粉末のIn
含量及びSn含量、平均粒径、加圧時比抵抗、凝集体の有
無を表２に示す。尚、ＩＴＯ粉末の平均粒径は、米国Qu
anta−chrome社製の Quantasorb QS−10を用いて測定し
た。また加圧時比抵抗は、ＩＴＯ粉末３ｇを 100kgf/cm
2 の圧力で断面積２cm2 の円柱状に加圧した時の値であ
る。さらに、凝集体の有無は、電子顕微鏡を用いて 100
00倍で３視野観察し、 0.2μm 以上の凝集体の有無を確
認することにより行なった。 Examples 1 to 5 ITO powder (average particle size: 0.050 μm) having no agglomerates and having good dispersibility prepared by the alkoxide method was placed in a 2-liter separable flask and heated using a mantle heater. While the mixture was being stirred, a deoxygenation treatment was performed through a nitrogen gas containing an alcohol gas. Table 1 shows the processing conditions at this time. In addition, the In and
Table 2 shows the content and Sn content, the average particle size, the specific resistance under pressure, and the presence or absence of aggregates. The average particle size of the ITO powder was determined by US Qu
The measurement was performed using Quantasorb QS-10 manufactured by anta-chrome. The specific resistance during pressurization is as follows: 3 g of ITO powder is 100 kgf / cm
In second pressure is a value when pressurized to a cylindrical cross-sectional area 2 cm 2. Furthermore, the presence or absence of aggregates was determined using an electron microscope.
This was performed by observing three visual fields at a magnification of 00 and confirming the presence or absence of aggregates of 0.2 μm or more.
【００１２】[0012]
【表１】 [Table 1]
【００１３】[0013]
【表２】 [Table 2]
【００１４】[0014]
【発明の効果】本発明の処理方法によれば、ＩＴＯ粉末
を凝集させることなく、該粉末を極めて低抵抗とするこ
とが可能となる。本発明の処理により低抵抗化されたＩ
ＴＯ粉末は、塗布による低抵抗ＩＴＯ膜の形成に使用さ
れる。According to the processing method of the present invention, it is possible to extremely reduce the resistance of the ITO powder without agglomerating the powder. I reduced in resistance by the treatment of the present invention
The TO powder is used for forming a low-resistance ITO film by coating.
Claims (3)
る不活性ガス雰囲気中で加熱することを特徴とするＩＴ
Ｏ粉末の低抵抗化処理方法。1. The method according to claim 1, wherein the ITO powder is heated in an inert gas atmosphere containing an alcohol gas.
A method for reducing the resistance of O powder.
項１に記載の方法。2. The method according to claim 1, wherein the heating is performed at a temperature of 200 to 450 ° C.
〜500 mg／Nlである請求項１に記載の方法。3. An alcohol gas concentration of 50 in an inert gas.
The method according to claim 1, wherein the amount is 500 mg / Nl.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20633891A JP3175212B2 (en) | 1991-07-23 | 1991-07-23 | Method for reducing resistance of ITO powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20633891A JP3175212B2 (en) | 1991-07-23 | 1991-07-23 | Method for reducing resistance of ITO powder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0524837A JPH0524837A (en) | 1993-02-02 |
| JP3175212B2 true JP3175212B2 (en) | 2001-06-11 |
Family
ID=16521649
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20633891A Expired - Lifetime JP3175212B2 (en) | 1991-07-23 | 1991-07-23 | Method for reducing resistance of ITO powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3175212B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3355733B2 (en) * | 1992-12-28 | 2002-12-09 | 三菱マテリアル株式会社 | Low resistance conductive pigment and method for producing the same |
| JP4600685B2 (en) * | 1994-05-25 | 2010-12-15 | 住友金属鉱山株式会社 | UV and near infrared shielding glass |
| US7462302B2 (en) * | 2006-01-20 | 2008-12-09 | Chung-Cheng Chang | Indium oxide based material and method for preparing the same |
-
1991
- 1991-07-23 JP JP20633891A patent/JP3175212B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0524837A (en) | 1993-02-02 |
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