JP3750461B2 - Transparent conductive layer forming coating liquid, transparent conductive layer and transparent conductive substrate - Google Patents
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【０００１】
【発明の属する技術分野】
本発明は、ブラウン管（ＣＲＴ）、プラズマディスプレイパネル(ＰＤＰ)、蛍光表示管(ＶＦＤ)、液晶ディスプレイ(ＬＣＤ)等表示装置の前面板等に利用される透明導電性基材の透明導電層形成用塗液とこれを用いて形成された透明導電層並びに透明導電性基材に係り、特に、高透過率で機械的強度に優れ、かつ、低抵抗、低反射率並びに耐候性等の諸特性を有すると共に、可視光線域での透過光線プロファイルに優れた透明導電性基材の製造を可能とする透明導電層形成用塗液とこれを用いて形成された透明導電層並びに透明導電性基材の改良に関するものである。
【０００２】
【従来の技術】
近年のオフィスオートメーション（ＯＡ）化によりオフィスに多くのＯＡ機器が導入され、ＯＡ機器のディスプレイと向き合って終日作業を行わねばならないという環境が最近珍しくない。
【０００３】
ところで、ＯＡ機器の一例としてコンピュータの陰極線管（上記ブラウン管とも称する：ＣＲＴ）等に接して仕事を行う場合、表示画面が見やすく、視覚疲労を感じさせないことの外に、ＣＲＴ表面の帯電によるほこりの付着や電撃ショックがないこと等が要求されている。更に、これ等に加えて最近ではＣＲＴから発生する低周波電磁波の人体に対する悪影響が懸念され、このような電磁波が外部に漏洩しないことがＣＲＴに対して望まれている。
【０００４】
そして、上記電磁波は偏向コイルやフライバックトランスから発生し、テレビジョンの大型化に伴って益々大量の電磁波が周囲に漏洩する傾向にある。
【０００５】
ところで、磁界の漏洩は偏向コイルの形状を変えるなどの工夫で大部分を防止することができる。一方、電界の漏洩もＣＲＴの前面ガラス表面に透明導電層を形成することにより防止することが可能である。
【０００６】
このような電界の漏洩に対する防止方法は、近年、帯電防止のために取られてきた対策と原理的には同一である。しかし、上記透明導電層は、帯電防止用に形成されていた導電層よりもはるかに高い導電性が求められている。すなわち、帯電防止用には表面抵抗で１０8Ω／□程度で十分とされているが、漏洩電界を防ぐ（電界シールド）ためには、少なくとも１０6Ω／□以下、好ましくは５×１０3Ω／□以下、さらに好ましくは１０3Ω／□以下である低抵抗の透明導電層を形成する必要がある。
【０００７】
そこで、上記要求に対処するため、従来よりいくつかの提案がなされているが、その中でも低コストでかつ低い表面抵抗を実現できる方法として、導電性微粒子をアルキルシリケート等の無機バインダーと共に溶媒中に分散した透明導電層形成用塗液をＣＲＴの前面ガラスに塗布・乾燥後、２００℃程度の温度で焼成する方法が知られている。
【０００８】
そして、この透明導電層形成用塗液を用いた方法は、真空蒸着やスパッタ法等他の透明導電層の形成方法に比べてはるかに簡便であり、製造コストも低く、ＣＲＴに処理可能な電界シールドとして極めて有利な方法である。
【０００９】
この方法に用いられる上記透明導電層形成用塗液として、導電性微粒子にインジウム錫酸化物（ＩＴＯ）を適用したものが知られている。しかし、得られる膜の表面抵抗が１０4〜１０6Ω／□と高いため、漏洩電界を十分に遮蔽するには電界キャンセル用の補正回路が必要となることから、その分、製造コストが割高となる問題があった。一方、上記導電性微粒子に金属粉を用いた透明導電層形成用塗液では、ＩＴＯを用いた塗液に比べ、若干、膜の透過率が低くなるものの、１０2〜１０3Ω／□という低抵抗膜が得られる。従って、上述した補正回路が必要なくなるためコスト的に有利となり、今後主流になると思われる。
【００１０】
そして、上記透明導電層形成用塗液に適用される金属微粒子としては、特開平８−７７８３２号公報や特開平９−５５１７５号公報等に示されるように空気中で酸化され難い、銀、金、白金、ロジウム、パラジウム等の貴金属に限られている。これは、貴金属以外の金属微粒子、例えば、鉄、ニッケル、コバルト等が適用された場合、大気雰囲気下でこれ等金属微粒子の表面に酸化物皮膜が必ず形成されてしまい透明導電層として良好な導電性が得られなくなるからである。
【００１１】
尚、上述した銀、金、白金、ロジウム、パラジウムなどの比抵抗を比較した場合、白金、ロジウム、パラジウムの比抵抗は、それぞれ１０．６、５．１、１０．８μΩ・ｃｍで、銀、金の１．６２、２．２μΩ・ｃｍに比べて高く、表面抵抗の低い透明導電層を形成するには銀微粒子や金微粒子を適用した方が有利なため、上記金属微粒子として銀微粒子や金微粒子等が主に利用されている。
【００１２】
但し、銀微粒子を適用した場合、硫化、酸化や食塩水、紫外線等による劣化が激しく耐候性に問題があるため、上記銀微粒子に代わって、最近、銀微粒子表面を金等でコーティングした金コート銀微粒子や金と金以外の複数の貴金属(例えば銀)から成る合金微粒子等の金含有貴金属微粒子も提案されている。
【００１３】
また、一方では表示画面を見易くするために、フェイスパネル表面に防眩処理を施して画面の反射を抑えることも行われている。この防眩処理は、微細な凹凸を設けて表面の拡散反射を増加させる方法によってもなされるが、この方法を用いた場合、解像度が低下して画質が落ちるためあまり好ましい方法とはいえない。従って、むしろ反射光が入射光に対して破壊的干渉を生ずるように、透明皮膜の屈折率と膜厚とを制御する干渉法によって防眩処理を行うことが好ましい。このような干渉法により低反射効果を得るため、一般的には高屈折率膜と低屈折率膜の光学的膜厚をそれぞれ１／４λと１／４λ、あるいは１／２λと１／４λに設定した二層構造膜が採用されており、前述のインジウム錫酸化物（ＩＴＯ）微粒子からなる膜もこの種の高屈折率膜として用いられている。
【００１４】
尚、金属においては、光学定数（ｎ−ｉｋ，ｎ：屈折率，ｉ2＝−１，ｋ：消衰係数）のうち、ｎの値は小さいがｋの値がＩＴＯ等と比べ極端に大きいため、金属微粒子からなる透明導電層を用いた場合でも、ＩＴＯ（高屈折率膜）と同様に、二層構造膜で光の干渉による反射防止効果が得られる。
【００１５】
【発明が解決しようとする課題】
ところで、金属膜は、本来、可視光線に対し透明でないため、上述した透明導電層の透過率を上げるためには透明導電層の膜厚を可能なかぎり薄くすることが望ましい。
【００１６】
しかし、透明導電層の膜厚を極端に薄くして金属微粒子径の１〜３倍程度までにしてしまうと、透明導電層内での金属微粒子の密度が低下するようになる。こうなると金属微粒子同士の接触が少なくなり、この結果、導電パスが十分に形成されなくなるため透明導電層における抵抗値の上昇を引起こす問題があった。
【００１７】
また、金は化学的に不活性なため、金属微粒子として上記金微粒子あるいは金含有貴金属微粒子が適用された透明導電層においては、これ等金微粒子若しくは金含有貴金属微粒子と透明導電層の一部を構成する酸化珪素等バインダーマトリックス間の結合が非常に弱い。このため、透明導電層の膜厚がそれ程薄くない場合においても膜の強度や耐候性が十分でない問題を有していた。
【００１８】
本発明はこの様な問題点に着目してなされたもので、その課題とするところは、高透過率で機械的強度に優れ、かつ、低抵抗、低反射率並びに耐候性等の諸特性を有すると共に、可視光線域での透過光線プロファイルに優れた透明導電性基材の製造を可能とする透明導電層形成用塗液とこれを用いて形成された透明導電層並びに透明導電性基材を提供することにある。
【００１９】
【課題を解決するための手段】
すなわち、請求項１に係る発明は、
溶媒とこの溶媒に分散された平均粒径１〜１００ｎｍでかつ金を５〜９５重量％含有する金含有貴金属微粒子を主成分とし、透明基板上に透明導電層を形成する透明導電層形成用塗液を前提とし、
上記金含有貴金属微粒子中の金成分１重量部に対して、メルカプト基、スルフィド基またはジスルフィド基を有する化合物が０．００４〜０．０２５重量部の割合で含まれていることを特徴とし、
また、請求項２に係る発明は、
請求項１記載の発明に係る透明導電層形成用塗液を前提とし、
上記金含有貴金属微粒子が、銀微粒子の表面に金をコーティングした金コート銀微粒子であることを特徴とし、
請求項３に係る発明は、
請求項１または２記載の発明に係る透明導電層形成用塗液を前提とし、
無機バインダーが含まれていることを特徴とし、
請求項４に係る発明は、
透明導電層形成用塗液を用いて形成される透明導電層を前提とし、
請求項１〜３のいずれかに記載の透明導電層形成用塗液を用いて形成されたことを特徴とし、
請求項５に係る発明は、
透明基板上に透明導電層を具備する透明導電性基材を前提とし、
請求項４記載の透明導電層を透明基板上に具備することを特徴とする。
【００２０】
【発明の実施の形態】
以下、本発明の実施の形態について詳細に説明する。
【００２１】
金は化学的に安定で、耐候性、耐薬品性、耐酸化性等に優れており、更に、比抵抗が銀、銅に次いで低いため、上記透明導電層の金属微粒子として金含有貴金属微粒子を用いれば、透明導電層における良好な導電性と高い化学的安定性の両立が図れる。しかし、金属は、元来、可視光において透明性をもたないため、透明導電層を形成するには金属微粒子を可視光の波長より小さくしかつ膜厚を非常に薄くしなければならない。また、高透過率化を目指すには、膜厚を更に薄くしていかなければならないが、透明導電層における膜厚を金属微粒子径の１〜３倍程度までに薄くすると、透明導電層内での金属微粒子の密度が低くなり、導電パスが十分に形成されなくなって抵抗値が上昇してしまう。
【００２２】
この問題を解決する方法としては、膜厚が非常に薄い透明導電層形成中において金属微粒子同士をある程度凝集させて高度に発達した網目状(ネットワーク)構造を形成する方法が考えられる。すなわち、この様な網目状構造においては、金属微粒子から成る網目状部分が導電パスとして機能する一方、網目状構造において形成された穴の部分が光線透過率を向上させる機能を果たすため、結果として低抵抗でかつ高透過率の透明導電層を形成できると考えられる。そして、金含有貴金属微粒子が適用された従来の透明導電層においても、この網目状構造は塗布後の成膜過程において形成されていたが、透明導電層における膜厚が非常に薄い場合においてはその形成が不十分となり低抵抗の透明導電層を形成することが困難であった。
【００２３】
本発明は、金と比較的強固な結合を形成するメルカプト基、スルフィド基またはジスルフィド基を有する化合物を透明導電層形成用塗液内に配合した場合、膜厚が非常に薄い透明導電層形成中においても、メルカプト基、スルフィド基またはジスルフィド基を有する上記化合物が、金含有貴金属微粒子に作用して塗布後の成膜過程において上述した網目状構造を容易に形成させる効果を有することを見出し完成されたもので、従来よりも高透過率の領域でも低い抵抗値を得ることが可能となる。
【００２４】
また、金含有貴金属微粒子における網目状構造の上記穴の部分を介して、透明基板と酸化珪素等バインダーマトリックスとの接触面積が増大するため透明基板とバインダーマトリックスの結合が強くなり、この結果、透明導電層における膜強度が高くなる効果も同時に得ることができる。
【００２５】
更に、メルカプト基、スルフィド基またはジスルフィド基を有する化合物の種類によっては、金含有貴金属微粒子と比較的強固に結合した上記化合物を介し、金含有貴金属微粒子と酸化珪素等バインダーマトリックスとの結合が図れるため、透明導電層における膜強度や耐候性の改善も図れる。例えば、金−銀２成分系貴金属微粒子(すなわち金含有貴金属微粒子)と酸化珪素のバインダーマトリックスとで構成された透明導電層を屋外に放置する(但し、この透明導電層はガラス基板上に形成されている)と、雨水や太陽光中の紫外線により１〜２ヶ月で膜劣化が起きて透明導電層における表面抵抗の上昇を生ずるが、メルカプト基、スルフィド基またはジスルフィド基を有する化合物が含まれた透明導電層形成用塗液を用いて形成された透明導電層においては、金含有貴金属微粒子の金含有量にもよるが３ヶ月以上の屋外放置でも透明導電層は全く変化せず、優れた耐候性を示す。また、透明導電層の膜強度についても、メルカプト基、スルフィド基またはジスルフィド基を有する化合物が含まれた透明導電層形成用塗液を用いて形成された透明導電層は従来の透明導電層形成用塗液が適用された透明導電層より優れている。
【００２６】
ここで、本発明における金含有貴金属微粒子はその平均粒径が１〜１００ｎｍであることを要する（請求項１）。上記微粒子において、１ｎｍ未満の場合、この微粒子の製造は困難であり、かつ、透明導電層形成用塗液中で凝集し易く実用的でないからである。また、１００ｎｍを超えると、形成された透明導電層の可視光線透過率が低くなり過ぎてしまい、仮に、膜厚を薄く設定して可視光線透過率を高くした場合でも、表面抵抗が高くなり過ぎてしまい実用的ではないからである。尚、ここで言う平均粒径とは、透過電子顕微鏡（ＴＥＭ）で観察される微粒子の平均粒径を示している。
【００２７】
また、上記金含有貴金属微粒子内の金の含有量は５〜９５重量％の範囲（請求項１）に設定され、好ましくは５０〜９０重量％の範囲に設定するとよい。金の含有量が５重量％未満だと、銀等金以外の貴金属に対する金の保護効果が弱まって数年という長期で考えた場合に紫外線等の影響による膜劣化が起こることがあり、９５重量％を超えるとコスト的に難があるからである。また、上記金含有貴金属微粒子としては、金と金以外の複数の貴金属から成る上述した合金微粒子等が考えられるが、中でも、銀微粒子表面に金をコーティングした金コート銀微粒子を挙げることができる(請求項２)。
【００２８】
次に、金含有貴金属微粒子として金コート銀微粒子が適用され、かつ、メルカプト基、スルフィド基またはジスルフィド基を有する化合物が含まれた本発明に係る透明導電層形成用塗液は以下のような方法で製造することができる。
【００２９】
まず、既知の方法［例えば、Carey−Lea法、Am.J.Sci.、37、47（1889）、Am.J.Sci.、38（1889）］により銀微粒子のコロイド分散液を調製する。すなわち、硝酸銀水溶液に、硫酸鉄（II）水溶液とクエン酸ナトリウム水溶液の混合液を加えて反応させ、沈降物を濾過・洗浄した後、純水を加えることにより簡単に銀微粒子のコロイド分散液（Ａｇ：０．１〜１０重量％）が調製される。この銀微粒子のコロイド分散液の調製方法は平均粒径１〜１００ｎｍの銀微粒子が分散されたものであれば任意でありかつこれに限定されるものではない。次いで、得られた銀微粒子のコロイド分散液に還元剤を加え、更に、アルカリ金属の金酸塩溶液とメルカプト基、スルフィド基またはジスルフィド基を有する化合物とを混合したものを加えることで、銀微粒子表面に金がコーティングされた金コート銀微粒子が得られかつこの金コート銀微粒子とメルカプト基、スルフィド基またはジスルフィド基を有する化合物とが反応してコーティング層表面に上記化合物が結合され若しくはこの化合物でコーティング層表面が覆われた金コート銀微粒子のコロイド状分散液を得ることができる。
【００３０】
尚、上記銀微粒子のコロイド分散液内にメルカプト基、スルフィド基またはジスルフィド基を有する化合物を混合するタイミングとしては、アルカリ金属の金酸塩溶液と同時に上記化合物を混合するコーティング時以外に、銀微粒子のコロイド分散液内に還元剤とアルカリ金属の金酸塩溶液を混合して銀微粒子表面を金でコーティングしたコーティング処理後に上記化合物を混合してもよい。但し、金のコーティング処理前において、銀微粒子のコロイド分散液内にメルカプト基、スルフィド基またはジスルフィド基を有する化合物を単独で混合させることは好ましくない。上記化合物を単独で混合させた場合、その後に金のコーティング処理を行なっても十分なコーティングができず、良好な金コート銀微粒子の分散液が得られないことがあるからである。この原因として、上記化合物を単独で混合させた場合にメルカプト基、スルフィド基またはジスルフィド基を有する上記化合物により銀微粒子表面が覆われていることが考えられる。
【００３１】
また、上記還元剤には、ヒドラジン（Ｎ2Ｈ4）、水素化ホウ素ナトリウム（ＮａＢＨ4）等の水素化ホウ素化合物、ホルムアルデヒド等を用いることができるが、銀微粒子のコロイド分散液に加えられたときに銀超微粒子の凝集を起こさず、金酸塩を金に還元できれば任意でありこれらに限定されるものではない。
【００３２】
例えば、金酸カリウム［ＫＡｕ（ＯＨ）4］をヒドラジンあるいは水素化ホウ素ナトリウムで還元する場合の還元反応は、それぞれ以下の様に示される。
【００３３】
ＫＡｕ（ＯＨ）4＋３／４Ｎ2Ｈ4→Ａｕ＋ＫＯＨ＋３Ｈ2Ｏ＋３／４Ｎ2↑
ＫＡｕ（ＯＨ）4＋３／４ＮａＢＨ4→Ａｕ＋ＫＯＨ＋３／４ＮａＯＨ
＋３／４Ｈ3ＢＯ3＋３／２Ｈ2↑
ここで、還元剤として上記水素化ホウ素ナトリウムを用いた場合、上記反応式から確認できるように還元反応により生じる電解質の濃度が高くなり、後述するように微粒子が凝集し易く、還元剤としての添加量が限られるため、用いる銀微粒子のコロイド分散液における銀濃度を高くできない不便さがある。
【００３４】
一方、還元剤として上記ヒドラジンを用いた場合、上記反応式から確認できるように還元反応により生じる電解質が少ないため還元剤としてより適している。
【００３５】
尚、金のコーティング原料として、アルカリ金属の金酸塩以外の塩、例えば塩化金酸（ＨＡｕＣｌ4）、または、塩化金酸塩（ＮａＡｕＣｌ4、ＫＡｕＣｌ4等）を用いると、ヒドラジンによる還元反応は以下のように示される。
【００３６】
ＸＡｕＣｌ4＋３／４Ｎ2Ｈ4→Ａｕ＋ＸＣｌ＋３ＨＣｌ＋３／４Ｎ2↑
（Ｘ＝Ｈ，Ｎａ，Ｋ等）
この様に塩化金酸等を適用した場合、上記金酸塩を用いた場合と比較して、還元反応による電解質濃度が高くなるだけでなく塩素イオンを生じるため、これが銀微粒子と反応し、難溶性の塩化銀を生成してしまうことから、本発明に係る透明導電層形成用塗液の原料に用いることは困難である。
【００３７】
次に、コーティング層表面にメルカプト基、スルフィド基またはジスルフィド基を有する化合物が結合され若しくはこの化合物で覆われた金コート銀微粒子のコロイド状分散液は、この後、透析、電気透析、イオン交換、限外濾過等の脱塩処理方法により分散液内の電解質濃度を下げることが好ましい。これは、電解質濃度を下げないとコロイドは電解質で一般に凝集してしまうからであり、この現象は、Schulze−Hardy則としても知られている。
【００３８】
次いで、上記脱塩処理が施された金コート銀微粒子のコロイド状分散液を減圧エバポレーター、限外濾過等の方法で濃縮処理して、メルカプト基、スルフィド基またはジスルフィド基を有する化合物が結合され若しくはこの化合物で覆われた上記金コート銀微粒子の分散濃縮液を得、この金コート銀微粒子の分散濃縮液に、溶媒単独若しくは無機バインダーが含まれた溶媒を混合して成分調整（微粒子濃度、水分濃度等）を行い、金属微粒子として金コート銀微粒子が適用された本発明に係る透明導電層形成用塗液が得られる(請求項１〜３)。
【００３９】
ここで、脱塩処理方式として限外濾過が適用された場合、この限外濾過は上述したように濃縮処理としても作用することから脱塩処理と濃縮処理を同時進行で行うことも可能である。また、上記溶媒については、金コート銀微粒子の分散濃縮液内に含まれる溶媒で代用してもよい(すなわち、溶媒単独の使用を省略してもよい)。また、無機バインダーについては、金コート銀微粒子の分散濃縮液あるいは溶媒内に含ませた状態で追加混合してもよいし、無機バインダーをそのまま追加混合してもよく、その混合の方法は任意である。また、上記溶媒としては特に制限はなく、塗布方法や製膜条件により、適宜に選定される。例えば、メタノール、エタノール、イソプロパノール、ブタノール、ベンジルアルコール、ジアセトンアルコール(ＤＡＡ)等のアルコール系溶媒、アセトン、メチルエチルケトン（ＭＥＫ）、メチルイソブチルケトン（ＭＩＢＫ）、シクロヘキサノン、イソホロン等のケトン系溶媒、プロピレングリコールメチルエーテル、プロピレングリコールエチルエーテル等のグリコール誘導体、フォルムアミド、Ｎ−メチルフォルムアミド、ジメチルホルムアミド（ＤＭＦ）、ジメチルアセトアミド、ジメチルスルフォキシド(ＤＭＳＯ)、Ｎ−メチル−２−ピロリドン（ＮＭＰ）等が挙げられるが、これらに限定されるものではない。
【００４１】
次に、この様にして得られた本発明に係る透明導電層形成用塗液を用いて、透明基板、および、この透明基板上に形成されかつ表面にメルカプト基、スルフィド基またはジスルフィド基を有する化合物が結合され若しくはこの化合物で覆われた平均粒径１〜１００ｎｍの金−銀２成分系貴金属微粒子等の金含有貴金属微粒子とバインダーマトリックスを主成分とする透明導電層とこの上に形成された透明コート層から成る透明２層膜でその主要部が構成される透明導電性基材を得ることができる。
【００４２】
そして、透明基板上に上記透明２層膜を形成するには以下の方法でこれを行うことができる。すなわち、溶媒と、平均粒径１〜１００ｎｍの金コート銀微粒子等の金含有貴金属微粒子と、メルカプト基、スルフィド基またはジスルフィド基を有する化合物(この化合物と金含有貴金属微粒子は反応して上述したように金含有貴金属微粒子表面は上記化合物により覆われている)とを主成分とする本発明に係る透明導電層形成用塗液を、ガラス基板、プラスチック基板等の透明基板上にスプレーコート、スピンコート、ワイヤーバーコート、ドクターブレードコート等の手法にて塗布し、必要に応じて乾燥した後、例えばシリカゾル等を主成分とする透明コート層形成用塗布液を上述した手法によりオーバーコートする。次に、オーバーコートした後、例えば５０〜３５０℃程度の温度で加熱処理を施しオーバーコートした透明コート層形成用塗布液の硬化を行って上記透明２層膜を形成する。尚、５０〜３５０℃程度の加熱処理では、金−銀２成分系貴金属微粒子等の金含有貴金属微粒子は金で保護されているため問題を生じないが、銀微粒子であると２００℃を超えた場合に酸化拡散により表面抵抗値が上昇し膜の劣化が生じる。
【００４３】
ここで、メルカプト基、スルフィド基またはジスルフィド基を有する化合物が配合された本発明に係る透明導電層形成用塗液を用いて透明導電層を形成した場合、上記化合物が含まれていない従来の透明導電層形成用塗液を適用した場合と比較して金含有貴金属微粒子の網目状構造化が発達し、高透過率領域での膜の導電性向上に大きく寄与している。
【００４４】
また、金含有貴金属微粒子における網目状構造の上記穴の部分を介し透明基板と酸化珪素等バインダーマトリックスとの接触面積が増大するため、透明基板とバインダーマトリックスの結合が強くなり、透明導電層における膜強度の向上も図れる。
【００４５】
更に、シリカゾル等を主成分とする透明コート層形成用塗布液を上述した手法によりオーバーコートした際、金含有貴金属微粒子と比較的強固に結合しているメルカプト基、スルフィド基またはジスルフィド基を有する化合物の官能基と上記シリカゾル等とが相互作用し、上記化合物を介して金含有貴金属微粒子とシリカゾル等との結合が図れるため、透明導電層における膜強度や耐候性の改善も図れる。
【００４６】
尚、上記シリカゾルとしては、オルトアルキルシリケートに水や酸触媒を加えて加水分解し、脱水縮重合を進ませた重合物、あるいは既に４〜５量体まで加水分解縮重合を進ませた市販のアルキルシリケート溶液を、さらに加水分解と脱水縮重合を進行させた重合物等を利用することができる。また、脱水縮重合が進行すると、溶液粘度が上昇して最終的には固化してしまうので、脱水縮重合の度合いについては、ガラス基板やプラスチック基板などの透明基板上に塗布可能な上限粘度以下のところに調整する。但し、脱水縮重合の度合いは上記上限粘度以下のレベルであれば特に指定されないが、膜強度、耐候性等を考慮すると重量平均分子量で５００から３０００程度が好ましい。そして、アルキルシリケート部分加水分解重合物は、透明２層膜の加熱焼成時に脱水縮重合反応がほぼ完結して、硬いシリケート膜（酸化ケイ素を主成分とする膜）になる。また、上記シリカゾルに、弗化マグネシウム微粒子、アルミナゾル、チタニアゾル、ジルコニアゾル等を加え、透明コート層の屈折率を調節して透明２層膜の反射率を変えることも可能である。
【００４７】
以上説明したように、本発明に係る透明導電層形成用塗液を適用して形成された透明導電層（請求項４）を具備する透明導電性基材（請求項５）は、従来より高透過率で機械的強度に優れ、低抵抗、低反射率並びに耐候性、耐紫外線性等の諸特性を有すると共に、可視光線域での透過光線プロファイルに優れているため、例えば、上述したブラウン管（ＣＲＴ）、プラズマディスプレイパネル（ＰＤＰ）、蛍光表示管（ＶＦＤ）、フィールドエミッションディスプレイ（ＦＥＤ）、エレクトロルミネッセンスディスプレイ（ＥＬＤ）、液晶ディスプレイ（ＬＣＤ）等表示装置における前面板等に用いることができる。
【００４８】
【実施例】
以下、本発明の実施例を具体的に説明するが、本発明はこれら実施例に限定されるものではない。また、本文中の「％」は、透過率、反射率、ヘーズ値の（％）を除いて「重量％」を示し、また「部」は「重量部」を示している。
【００４９】
［実施例１］
前述のＣａｒｅｙ−Ｌｅａ法により銀微粒子のコロイド分散液を調製した。
【００５０】
具体的には、９％硝酸銀水溶液３３ｇに、２３％硫酸鉄（II）水溶液３９ｇと３７．５％クエン酸ナトリウム水溶液４８ｇの混合液を加えた後、沈降物をろ過・洗浄した後、純水を加えて、銀微粒子のコロイド分散液（Ａｇ：０．１５％）を調製した。この銀微粒子のコロイド分散液８０ｇにヒドラジン１水和物（Ｎ2Ｈ4・Ｈ2Ｏ）の１％水溶液１０．０ｇを加えて攪拌しながら、金酸カリウム［ＫＡｕ（ＯＨ）4］水溶液（Ａｕ：０．１５％）３２０ｇと１％チオリンゴ酸水溶液０．６ｇの混合液を加え、チオリンゴ酸で覆われた金コート銀微粒子のコロイド分散液を得た。
【００５１】
チオリンゴ酸で覆われた金コート銀微粒子のコロイド分散液をイオン交換樹脂（三菱化学社製商品名ダイヤイオンＳＫ１Ｂ，ＳＡ２０ＡＰ）で脱塩した後、限外ろ過により濃縮した液にエタノール（ＥＡ）とジアセトンアルコール(ＤＡＡ)を加え、チオリンゴ酸で覆われた金コート銀微粒子が含まれた実施例１に係る透明導電層形成用塗液（Ａｇ：０．０６％、Ａｕ：０．２５％、チオリンゴ酸：０．００３％、水：９．７％、ＤＡＡ：１０．０％、ＥＡ：７９．９％）を得た。得られた実施例１に係る透明導電層形成用塗液を透過電子顕微鏡で観察した結果、チオリンゴ酸で覆われた金コート銀微粒子の平均粒径は、７．８ｎｍであった。
【００５２】
次に、この実施例１に係る透明導電層形成用塗液を、３５℃に加熱されたガラス基板（厚さ３ｍｍのソーダライムガラス）上に、スピンコート（１５０ｒｐｍ，６０秒間）した後、続けて、シリカゾル液から成る透明コート層形成用塗布液をスピンコート（１５０ｒｐｍ，６０秒間）し、更に、２００℃、２０分間硬化させて、チオリンゴ酸で覆われた金−銀２成分系貴金属微粒子を有する透明導電層と、酸化ケイ素を主成分とするシリケート膜から成る透明コート層とで構成された透明２層膜付きのガラス基板、すなわち、実施例１に係る透明導電性基材を得た。
【００５３】
尚、上記２００℃、２０分間の加熱処理を施した際、金コート銀微粒子内においては金、銀の熱拡散による合金化層形成の可能性があり、上記金コート銀微粒子内のコート層が金単体で構成されているとは限らない場合が存在する。このため、本明細書では、透明導電層形成用塗液内において金コート銀微粒子が適用されている場合においても、金と銀とで構成される透明導電層内の微粒子については、金コート銀微粒子と表現せずに上述したように金−銀２成分系貴金属微粒子と表現する。
【００５４】
ここで、上記シリカゾル液は、メチルシリケート５１（コルコート社製商品名）を１９．６部、エタノール５７．８部、１％硝酸水溶液７．９部、純水１４．７部を用いて、ＳｉＯ2（酸化ケイ素）固形分濃度が１０％で、重量平均分子量が２８５０のものを調製し、最終的に、ＳｉＯ2固形分濃度が０．８％となるようにイソプロピルアルコール（ＩＰＡ）とｎ−ブタノール（ＮＢＡ）の混合物（ＩＰＡ／ＮＢＡ＝３／１）により希釈して得ている。
【００５５】
そして、ガラス基板上に形成された透明２層膜の膜特性（表面抵抗、可視光線透過率、透過率の標準偏差、ヘーズ値、ボトム反射率／ボトム波長）を以下の表１に示す。
【００５６】
尚、上記ボトム反射率とは透明導電性基材の反射プロファイルにおいて極小の反射率をいい、ボトム波長とは反射率が極小における波長を意味している。
【００５７】
また、製造された実施例１に係る透明導電性基材の反射プロファイルを図１に、また、透過プロファイルを図２に合わせて示す。
【００５８】
また、表１において可視光線波長域（３８０〜７８０ｎｍ）の透明基板（ガラス基板）を含まない透明２層膜だけの透過率は、以下の様にして求められている。
【００５９】
すなわち、
透明基板を含まない透明２層膜だけの透過率（％）
＝［（透明基板ごと測定した透過率）／（透明基板の透過率）］×１００
ここで、本明細書においては、特に言及しない限り、透過率としては、透明基板を含まない透過率(すなわち透明２層膜の透過率)を用いている。
【００６０】
また、透明２層膜の表面抵抗は、三菱化学(株)製の表面抵抗計ロレスタＡＰ（ＭＣＰ−Ｔ４００）を用い測定した。ヘイズ値と可視光線透過率は、透明基板ごと、村上色彩技術研究所製のヘイズメーター（ＨＲ−２００）を用いて測定した。反射率および反射・透過プロファイルは、日立製作所(株)製分光光度計（Ｕ−４０００）を用いて測定した。また、チオリンゴ酸で覆われた金コート銀微粒子の粒径は日本電子製の透過電子顕微鏡で評価している。
【００６１】
［実施例２］
実施例１で調製したチオリンゴ酸により覆われた金コート銀微粒子コロイド分散液の濃縮液に、エタノール（ＥＡ）、ジアセトンアルコール(ＤＡＡ)と無機バインダーとしてテトラメチルシリケートの４量体(コルコート社製商品名メチルシリケート５１)を加えて、チオリンゴ酸で覆われた平均粒径７．８ｎｍの金コート銀微粒子が含まれた実施例２に係る透明導電層形成用塗液（Ａｇ：０．０６％、Ａｕ：０．２５％、チオリンゴ酸：０．００３％、ＳｉＯ2：０．０１％、水：９．７％、ＤＡＡ：１０．０％、ＥＡ：７９．９％）を得た。
【００６２】
そして、この実施例２に係る透明導電層形成用塗液を用いた以外は、実施例１と同様に行い、チオリンゴ酸で覆われた金−銀２成分系貴金属微粒子を有する透明導電層と、酸化ケイ素を主成分とするシリケート膜から成る透明コート層とで構成された透明２層膜付きのガラス基板、すなわち、実施例２に係る透明導電性基材を得た。
【００６３】
ガラス基板上に形成された透明２層膜の膜特性を以下の表１に示す。
【００６４】
［実施例３］
実施例１と同様の方法で調製した銀微粒子のコロイド分散液８０ｇを用い、かつ、ヒドラジン１水和物（Ｎ2Ｈ4・Ｈ2Ｏ）の１％水溶液７．０ｇ、金酸カリウム［ＫＡｕ（ＯＨ）4］水溶液（Ａｕ：０．１５％）２４０ｇとチオサリチル酸ナトリウムの１％水溶液０．１６ｇを用いると共に、実施例１と同様の処理を行なってチオサリチル酸で覆われた平均粒径９．１ｎｍの金コート銀微粒子が含まれた実施例３に係る透明導電層形成用塗液（Ａｇ：０．０８％、Ａｕ：０．２２％、チオサリチル酸：０．００２％、水：１２．１％、ＤＡＡ：１０．０％、ＥＡ：７７．４％）を得た。
【００６５】
そして、この実施例３に係る透明導電層形成用塗液を用いた以外は、実施例１と同様に行い、チオサリチル酸で覆われた金−銀２成分系貴金属微粒子を有する透明導電層と、酸化ケイ素を主成分とするシリケート膜から成る透明コート層とで構成された透明２層膜付きのガラス基板、すなわち、実施例３に係る透明導電性基材を得た。
【００６６】
ガラス基板上に形成された透明２層膜の膜特性を以下の表１に示す。
【００６７】
［実施例４］
実施例１と同様の方法で調製した銀微粒子のコロイド分散液８０ｇを用い、かつ、ヒドラジン１水和物（Ｎ2Ｈ4・Ｈ2Ｏ）の１％水溶液１０．０ｇ、金酸カリウム［ＫＡｕ（ＯＨ）4］水溶液（Ａｕ：０．１５％）３２０ｇとチオジグリコール酸の１％水溶液１．２ｇを用いると共に、実施例１と同様の処理を行なってチオジグリコール酸で覆われた平均粒径８．８ｎｍの金コート銀微粒子が含まれた実施例４に係る透明導電層形成用塗液（Ａｇ：０．０６％、Ａｕ：０．２４％、チオジグリコール酸：０．００６％、水：１０．２％、ＤＡＡ：１０．０％、ＥＡ：７９．４％）を得た。
【００６８】
そして、この実施例４に係る透明導電層形成用塗液を用いた以外は、実施例１と同様に行い、チオジグリコール酸で覆われた金−銀２成分系貴金属微粒子を有する透明導電層と、酸化ケイ素を主成分とするシリケート膜から成る透明コート層とで構成された透明２層膜付きのガラス基板、すなわち、実施例４に係る透明導電性基材を得た。
【００６９】
ガラス基板上に形成された透明２層膜の膜特性を以下の表１に示す。
【００７０】
［実施例５］
実施例１と同様の方法で調製した銀微粒子のコロイド分散液８０ｇを用い、かつ、ヒドラジン１水和物（Ｎ2Ｈ4・Ｈ2Ｏ）の１％水溶液１０．０ｇ、金酸カリウム［ＫＡｕ（ＯＨ）4］水溶液（Ａｕ：０．１５％）３２０ｇとジチオジグリコール酸の１％水溶液０．２ｇを用いると共に、実施例１と同様の処理を行なってジチオジグリコール酸で覆われた平均粒径７．１ｎｍの金コート銀微粒子が含まれた実施例５に係る透明導電層形成用塗液（Ａｇ：０．０５％、Ａｕ：０．２３％、ジチオジグリコール酸：０．００１％、水：９．３％、ＤＡＡ：１０．０％、ＥＡ：８０．３％）を得た。
【００７１】
そして、この実施例５に係る透明導電層形成用塗液を用いた以外は、実施例１と同様に行い、ジチオジグリコール酸で覆われた金−銀２成分系貴金属微粒子を有する透明導電層と、酸化ケイ素を主成分とするシリケート膜から成る透明コート層とで構成された透明２層膜付きのガラス基板、すなわち、実施例５に係る透明導電性基材を得た。
【００７２】
ガラス基板上に形成された透明２層膜の膜特性を以下の表１に示す。
【００７３】
［実施例６］
実施例１と同様の方法で調製した銀微粒子のコロイド分散液８０ｇを用い、かつ、ヒドラジン１水和物（Ｎ2Ｈ4・Ｈ2Ｏ）の１％水溶液１０．０ｇ、金酸カリウム［ＫＡｕ（ＯＨ）4］水溶液（Ａｕ：０．１５％）３２０ｇとγ−メルカプトプロピルトリメトキシシランの１％水溶液０．６ｇを用いると共に、実施例１と同様の処理を行なってγ−メルカプトプロピルトリメトキシシラン(実際にはメトキシ基は塗液中で加水分解されてシラノール基［Ｓｉ−ＯＨ］が形成されている)で覆われた平均粒径８．３ｎｍの金コート銀微粒子が含まれた実施例６に係る透明導電層形成用塗液（Ａｇ：０．０６％、Ａｕ：０．２３％、γ−メルカプトプロピルトリメトキシシラン：０．００３％、水：８．６％、ＤＡＡ：１０．０％、ＥＡ：８１．０％）を得た。
【００７４】
そして、この実施例６に係る透明導電層形成用塗液を用いた以外は、実施例１と同様に行い、γ−メルカプトプロピルトリメトキシシランで覆われた金−銀２成分系貴金属微粒子を有する透明導電層と、酸化ケイ素を主成分とするシリケート膜から成る透明コート層とで構成された透明２層膜付きのガラス基板、すなわち、実施例６に係る透明導電性基材を得た。
【００７５】
ガラス基板上に形成された透明２層膜の膜特性を以下の表１に示す。
【００７６】
［比較例］
実施例１と同様の方法で調製した銀微粒子のコロイド分散液８０ｇを用い、かつ、ヒドラジン１水和物（Ｎ2Ｈ4・Ｈ2Ｏ）の１％水溶液７．０ｇ、金酸カリウム［ＫＡｕ（ＯＨ）4］水溶液（Ａｕ：０．１５％）２４０ｇと１％高分子分散剤水溶液０．４８ｇを用いると共に、実施例１と同様の処理を行なって平均粒径８．３ｎｍの金コート銀微粒子が分散された比較例に係る透明導電層形成用塗液（Ａｇ：０．０８％、Ａｕ：０．２３％、水：１２．０％、ＤＡＡ：１０．０％、ＥＡ：７７．９％）を得た。
【００７７】
そして、この比較例に係る透明導電層形成用塗液を用いた以外は、実施例１と同様に行い、金−銀２成分系貴金属微粒子を有する透明導電層と、酸化ケイ素を主成分とするシリケート膜から成る透明コート層とで構成された透明２層膜付きのガラス基板、すなわち、比較例に係る透明導電性基材を得た。
【００７８】
ガラス基板上に形成された透明２層膜の膜特性を以下の表１に示す。
【００７９】
【表１】
実施例１〜６に係る透明導電性基材と比較例に係る透明導電性基材を、屋外の直射日光があたる条件下に３ヶ月間放置し、透明基板（ガラス基板）上に設けた透明２層膜の表面抵抗値とその外観を調べた。この結果を以下の表２に示す。
【００８０】
【表２】
実施例１〜６に係る透明導電性基材と比較例に係る透明導電性基材について、消しゴム試験（すなわち、各透明導電性基材の膜表面を消しゴムで荷重１ｋｇの条件下５０往復および１００往復擦り続け、膜表面の擦傷を観察し評価する試験）を行い、透明基板（ガラス基板）上に設けた透明２層膜の膜強度を調べた。
【００８１】
結果を以下の表３に示す。
【００８２】
【表３】
１．表１に示された結果から明らかなように各実施例に係る透明２層膜の表面抵抗は６４８〜９２５Ω／□の範囲内にあり、かつ、透明２層膜の可視光線透過率も８６．７〜８７．５％の範囲内にあることから、各実施例に係る透明２層膜は高透過率でかつ低抵抗の特性を具備していることが確認できる。
【００８３】
これに対し、比較例に係る透明２層膜の可視光線透過率は８６．９％であり高透過率の特性は具備するが、透明２層膜の表面抵抗は２２５３Ω／□と高く低抵抗の特性は具備していないことが確認できる。
【００８４】
２．また、表２に示された結果から明らかなように各実施例に係る透明２層膜の外観は変化しておらず、かつ、透明２層膜における表明抵抗の初期値と屋外放置３ヶ月の値も大きな変化がない。従って、各実施例に係る透明２層膜の耐候性についても十分な特性を備えていることが確認できる。
【００８５】
他方、比較例に係る透明２層膜の外観は変化していないが、透明２層膜における表明抵抗の初期値(２２５３Ω／□)と屋外放置３ヶ月の値(５７９５Ω／□)からその値が大きく変化しており、比較例に係る透明２層膜の耐候性は不十分であることが確認できる。
【００８６】
３．更に、表３の結果から、比較例に較べて各実施例に係る透明２層膜の機械的強度も十分であり、各実施例においてはその透明２層膜における機械的強度についても十分な特性を備えていることが確認できる。
【００８７】
【発明の効果】
請求項１〜３記載の発明に係る透明導電層形成用塗液によれば、
高透過率で機械的強度に優れ、かつ、低抵抗、低反射率並びに耐候性等の諸特性を有すると共に、可視光線域での透過光線プロファイルに優れた請求項４記載の発明に係る透明導電層を具備する請求項５記載の発明に係る透明導電性基材を製造できる効果を有する。
【図面の簡単な説明】
【図１】実施例１に係る透明導電性基材の反射プロファイルを示すグラフ図。
【図２】実施例１に係る透明導電性基材の透過プロファイルを示すグラフ図。[0001]
BACKGROUND OF THE INVENTION
The present invention is for forming a transparent conductive layer of a transparent conductive substrate used for a front panel of a display device such as a cathode ray tube (CRT), a plasma display panel (PDP), a fluorescent display tube (VFD), a liquid crystal display (LCD), etc. Coating liquid , Transparent conductive layer formed using the same, and transparent conductive substrate In particular, a transparent conductive substrate having high transmittance, excellent mechanical strength, low resistance, low reflectance, weather resistance, and other properties, as well as excellent transmitted light profile in the visible light range. Coating liquid for forming transparent conductive layers , Transparent conductive layer formed using the same, and transparent conductive substrate It is about improvement.
[0002]
[Prior art]
In recent years, office automation (OA) has led to the introduction of many OA devices in the office, and it is not uncommon recently to have to work all day while facing the display of OA devices.
[0003]
By the way, when working in contact with a cathode ray tube (also referred to as a cathode ray tube: CRT) of a computer as an example of OA equipment, the display screen is easy to see and the visual fatigue is not felt. It is required that there is no adhesion or electric shock. In addition to these, recently, there are concerns about the adverse effects of low frequency electromagnetic waves generated from CRTs on the human body, and it is desired for CRTs to prevent such electromagnetic waves from leaking to the outside.
[0004]
And the said electromagnetic waves generate | occur | produce from a deflection coil or a flyback transformer, and there exists a tendency for a lot of electromagnetic waves to leak to circumference | surroundings with the enlargement of a television.
[0005]
By the way, most of leakage of the magnetic field can be prevented by changing the shape of the deflection coil. On the other hand, electric field leakage can also be prevented by forming a transparent conductive layer on the front glass surface of the CRT.
[0006]
The method for preventing such electric field leakage is in principle the same as the countermeasures taken for the prevention of charging in recent years. However, the transparent conductive layer is required to have a much higher conductivity than the conductive layer formed for antistatic purposes. That is, the surface resistance is 10 for antistatic. 8 Ω / □ is sufficient, but at least 10 to prevent leakage electric field (electric field shielding). 6 Ω / □ or less, preferably 5 × 10 Three Ω / □ or less, more preferably 10 Three It is necessary to form a transparent conductive layer having a low resistance of Ω / □ or less.
[0007]
Thus, several proposals have been made in the past in order to cope with the above requirements. Among them, as a method capable of realizing low surface resistance at low cost, the conductive fine particles are placed in a solvent together with an inorganic binder such as an alkyl silicate. A method is known in which a dispersed coating liquid for forming a transparent conductive layer is applied to a CRT front glass and dried, followed by baking at a temperature of about 200 ° C.
[0008]
The method using the coating liquid for forming the transparent conductive layer is much simpler than other methods for forming a transparent conductive layer such as vacuum deposition and sputtering, has a low manufacturing cost, and can be processed into a CRT. This is a very advantageous method as a shield.
[0009]
As a coating liquid for forming the transparent conductive layer used in this method, one in which indium tin oxide (ITO) is applied to conductive fine particles is known. However, the resulting film has a surface resistance of 10 Four -10 6 Since it is as high as Ω / □, a correction circuit for canceling the electric field is necessary to sufficiently shield the leakage electric field, and there is a problem that the manufacturing cost is increased accordingly. On the other hand, the coating liquid for forming a transparent conductive layer using metal powder as the conductive fine particles has a slightly lower film transmittance than the coating liquid using ITO. 2 -10 Three A low resistance film of Ω / □ can be obtained. Accordingly, the above-described correction circuit is not necessary, which is advantageous in terms of cost and is expected to become mainstream in the future.
[0010]
As the metal fine particles applied to the coating liquid for forming the transparent conductive layer, silver, gold, and the like, which are not easily oxidized in the air as disclosed in JP-A-8-77832 and JP-A-9-55175, etc. , Platinum, rhodium, palladium and other precious metals. This is because, when metal fine particles other than noble metals, such as iron, nickel, cobalt, etc., are applied, an oxide film is always formed on the surface of these metal fine particles in the air atmosphere, and a good conductive property as a transparent conductive layer. This is because sex cannot be obtained.
[0011]
In addition, when comparing the specific resistances of silver, gold, platinum, rhodium, palladium, etc., the specific resistances of platinum, rhodium, and palladium are 10.6, 5.1, 10.8 μΩ · cm, silver, In order to form a transparent conductive layer having a surface resistance higher than 1.62 and 2.2 μΩ · cm of gold and having a low surface resistance, it is more advantageous to apply silver fine particles or gold fine particles. Fine particles are mainly used.
[0012]
However, when silver fine particles are applied, deterioration due to sulfidation, oxidation, saline solution, ultraviolet rays, etc. is severe and there is a problem with weather resistance. Gold-containing noble metal fine particles such as silver fine particles and alloy fine particles composed of a plurality of noble metals other than gold and gold (for example, silver) have also been proposed.
[0013]
On the other hand, in order to make the display screen easier to see, anti-glare treatment is performed on the face panel surface to suppress screen reflection. This anti-glare treatment is also performed by a method of increasing the diffuse reflection of the surface by providing fine irregularities. However, when this method is used, it is not a preferable method because the resolution is lowered and the image quality is lowered. Accordingly, it is preferable to perform the antiglare treatment by an interference method that controls the refractive index and the film thickness of the transparent film so that the reflected light causes destructive interference with the incident light. In order to obtain a low reflection effect by such an interference method, the optical film thicknesses of the high refractive index film and the low refractive index film are generally set to 1 / 4λ and 1 / 4λ, or 1 / 2λ and 1 / 4λ, respectively. A set two-layer structure film is employed, and a film made of the aforementioned indium tin oxide (ITO) fine particles is also used as this kind of high refractive index film.
[0014]
For metals, optical constants (n-ik, n: refractive index, i 2 = -1, k: extinction coefficient), the value of n is small, but the value of k is extremely large compared to ITO or the like. Therefore, even when a transparent conductive layer made of metal fine particles is used, ITO (high refractive index) Similarly to the film), the antireflection effect due to the interference of light can be obtained with the two-layer structure film.
[0015]
[Problems to be solved by the invention]
By the way, since the metal film is originally not transparent to visible light, it is desirable to make the film thickness of the transparent conductive layer as thin as possible in order to increase the transmittance of the transparent conductive layer described above.
[0016]
However, if the film thickness of the transparent conductive layer is extremely reduced to about 1 to 3 times the metal fine particle diameter, the density of the metal fine particles in the transparent conductive layer decreases. In this case, the contact between the metal fine particles is reduced, and as a result, a sufficient conductive path is not formed, causing a problem of increasing the resistance value in the transparent conductive layer.
[0017]
Further, since gold is chemically inert, in the transparent conductive layer to which the gold fine particles or the gold-containing noble metal fine particles are applied as the metal fine particles, the gold fine particles or the gold-containing noble metal fine particles and a part of the transparent conductive layer are used. Bonding between binder matrices such as silicon oxide is very weak. For this reason, even when the film thickness of the transparent conductive layer is not so thin, there is a problem that the strength and weather resistance of the film are not sufficient.
[0018]
The present invention has been made paying attention to such problems, and the problem is that it has high transmittance, excellent mechanical strength, and various properties such as low resistance, low reflectance, and weather resistance. And a transparent conductive layer forming coating solution that enables the production of a transparent conductive substrate having an excellent transmitted light profile in the visible light region , Transparent conductive layer formed using the same, and transparent conductive substrate Is to provide.
[0019]
[Means for Solving the Problems]
That is, the invention according to claim 1
Solvent and average particle size 1-100 nm dispersed in this solvent And Based on gold-containing noble metal fine particles containing 5 to 95% by weight of gold, based on a transparent conductive layer forming coating solution for forming a transparent conductive layer on a transparent substrate,
For 1 part by weight of the gold component in the gold-containing noble metal fine particles, A compound having a mercapto group, sulfide group or disulfide group 0.004 to 0.025 parts by weight It is characterized by being included,
The invention according to
Based on the coating liquid for forming a transparent conductive layer according to the invention of claim 1,
The gold-containing noble metal fine particles are gold-coated silver fine particles in which gold is coated on the surface of silver fine particles,
The invention according to claim 3
Based on the coating liquid for forming a transparent conductive layer according to
It contains an inorganic binder,
The invention according to
On the premise of a transparent conductive layer formed using a coating liquid for forming a transparent conductive layer,
It was formed using the coating liquid for transparent conductive layer formation in any one of Claims 1-3,
The invention according to claim 5
Assuming a transparent conductive substrate with a transparent conductive layer on a transparent substrate,
A transparent conductive layer according to
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0021]
Gold is chemically stable and has excellent weather resistance, chemical resistance, oxidation resistance, etc. Furthermore, since specific resistance is the second lowest after silver and copper, gold-containing noble metal fine particles are used as metal fine particles in the transparent conductive layer. If used, both good conductivity and high chemical stability in the transparent conductive layer can be achieved. However, since metal originally has no transparency in visible light, in order to form a transparent conductive layer, the metal fine particles must be made smaller than the wavelength of visible light and the film thickness must be very thin. Moreover, in order to increase the transmittance, the film thickness must be further reduced. However, if the film thickness in the transparent conductive layer is reduced to about 1 to 3 times the metal fine particle diameter, As a result, the density of the metal fine particles becomes low, and a sufficient conductive path is not formed, resulting in an increase in resistance.
[0022]
As a method for solving this problem, a method of forming a highly developed network (network) structure by agglomerating metal fine particles to some extent during formation of a transparent conductive layer having a very thin film thickness can be considered. That is, in such a network structure, the mesh portion made of metal fine particles functions as a conductive path, while the hole portion formed in the mesh structure functions to improve the light transmittance. It is considered that a transparent conductive layer having low resistance and high transmittance can be formed. And even in the conventional transparent conductive layer to which the gold-containing noble metal fine particles are applied, this network structure was formed in the film forming process after coating, but when the film thickness in the transparent conductive layer is very thin, Formation was insufficient and it was difficult to form a low-resistance transparent conductive layer.
[0023]
In the present invention, when a compound having a mercapto group, sulfide group or disulfide group that forms a relatively strong bond with gold is blended in a coating liquid for forming a transparent conductive layer, a transparent conductive layer is being formed with a very thin film thickness. In addition, the above compound having a mercapto group, sulfide group or disulfide group was found to have an effect of easily forming the above-described network structure in the film forming process after coating by acting on the gold-containing noble metal fine particles. Therefore, it is possible to obtain a low resistance value even in a region having a higher transmittance than in the past.
[0024]
In addition, the contact area between the transparent substrate and the binder matrix such as silicon oxide is increased through the hole portion of the network structure in the gold-containing noble metal fine particles, so that the bond between the transparent substrate and the binder matrix becomes strong. The effect of increasing the film strength in the conductive layer can be obtained at the same time.
[0025]
Furthermore, depending on the type of the compound having a mercapto group, sulfide group or disulfide group, the gold-containing noble metal fine particles can be bonded to the binder matrix such as silicon oxide through the above-mentioned compound that is relatively strongly bonded to the gold-containing noble metal fine particles. In addition, the film strength and weather resistance of the transparent conductive layer can be improved. For example, a transparent conductive layer composed of gold-silver binary noble metal fine particles (that is, gold-containing noble metal fine particles) and a silicon oxide binder matrix is left outdoors (however, this transparent conductive layer is formed on a glass substrate). )), The film deterioration occurs in 1 to 2 months due to rainwater or ultraviolet rays in sunlight, resulting in an increase in surface resistance in the transparent conductive layer, but a compound having a mercapto group, sulfide group or disulfide group was included. In the transparent conductive layer formed using the coating liquid for forming the transparent conductive layer, although it depends on the gold content of the gold-containing noble metal fine particles, the transparent conductive layer does not change at all even when left outdoors for 3 months or more, and has excellent weather resistance. Showing gender. In addition, regarding the film strength of the transparent conductive layer, the transparent conductive layer formed using a coating liquid for forming a transparent conductive layer containing a compound having a mercapto group, sulfide group or disulfide group is used for forming a conventional transparent conductive layer. It is superior to the transparent conductive layer to which the coating liquid is applied.
[0026]
Here, the gold-containing noble metal fine particles in the present invention are required to have an average particle diameter of 1 to 100 nm (claim 1). If the fine particles are less than 1 nm, it is difficult to produce the fine particles, and they are likely to aggregate in the coating liquid for forming a transparent conductive layer and are not practical. If the thickness exceeds 100 nm, the visible light transmittance of the formed transparent conductive layer becomes too low, and even if the film thickness is set thin and the visible light transmittance is increased, the surface resistance becomes too high. This is because it is not practical. In addition, the average particle diameter said here has shown the average particle diameter of the microparticles | fine-particles observed with a transmission electron microscope (TEM).
[0027]
The gold content in the gold-containing noble metal fine particles is set in the range of 5 to 95% by weight (Claim 1), and preferably in the range of 50 to 90% by weight. If the gold content is less than 5% by weight, the protective effect of gold against precious metals other than silver and other gold is weakened, and film deterioration due to the influence of ultraviolet rays or the like may occur in the long term of several years. This is because if it exceeds 50%, there is a problem in cost. Examples of the gold-containing noble metal fine particles include the above-described alloy fine particles composed of a plurality of noble metals other than gold and gold. Among them, gold-coated silver fine particles in which the surface of the silver fine particles is coated with gold can be exemplified ( Claim 2).
[0028]
next, Gold-containing noble The coating liquid for forming a transparent conductive layer according to the present invention, in which gold-coated silver fine particles are applied as metal fine particles and a compound having a mercapto group, sulfide group or disulfide group is contained, can be produced by the following method. it can.
[0029]
First, a colloidal dispersion of silver fine particles is prepared by a known method [for example, Carey-Lea method, Am. J. Sci., 37, 47 (1889), Am. J. Sci., 38 (1889)]. That is, a silver nitrate aqueous solution is mixed with an iron (II) sulfate aqueous solution and a sodium citrate aqueous solution and reacted. After the precipitate is filtered and washed, pure water is added to the colloidal dispersion of silver particles ( Ag: 0.1 to 10% by weight) is prepared. The method for preparing the colloidal dispersion of silver fine particles is arbitrary and is not limited to this as long as silver fine particles having an average particle diameter of 1 to 100 nm are dispersed. Next, a reducing agent is added to the obtained colloidal dispersion of silver fine particles, and further, a mixture of an alkali metal oxalate solution and a compound having a mercapto group, a sulfide group or a disulfide group is added. Gold-coated silver fine particles coated with gold on the surface are obtained, and the gold-coated silver fine particles react with a compound having a mercapto group, sulfide group or disulfide group to bond the above compound to the surface of the coating layer, or with this compound A colloidal dispersion of gold-coated silver fine particles with the coating layer surface covered can be obtained.
[0030]
The timing of mixing the compound having a mercapto group, sulfide group or disulfide group into the colloidal dispersion of the silver fine particles is not limited to the time of coating in which the compound is mixed simultaneously with the alkali metal oxalate solution. The above compound may be mixed after a coating treatment in which a reducing agent and an alkali metal aurate solution are mixed in a colloidal dispersion of the above and the surface of silver fine particles is coated with gold. However, it is not preferable to mix a compound having a mercapto group, sulfide group or disulfide group alone in the colloidal dispersion of silver fine particles before the gold coating treatment. This is because when the above compounds are mixed singly, even if a gold coating treatment is performed thereafter, sufficient coating cannot be performed, and a good gold-coated silver fine particle dispersion may not be obtained. As a cause of this, it is considered that the surface of the silver fine particles is covered with the compound having a mercapto group, sulfide group or disulfide group when the compound is mixed alone.
[0031]
The reducing agent includes hydrazine (N 2 H Four ), Sodium borohydride (NaBH) Four Boron hydride compounds such as), formaldehyde, etc. can be used, but these are optional as long as they do not cause aggregation of silver ultrafine particles when added to a colloidal dispersion of silver fine particles and can reduce the gold salt to gold. It is not limited to.
[0032]
For example, potassium metalate [KAu (OH) Four ] Are reduced as follows using hydrazine or sodium borohydride.
[0033]
KAu (OH) Four + 3 / 4N 2 H Four → Au + KOH + 3H 2 O + 3 / 4N 2 ↑
KAu (OH) Four + 3 / 4NaBH Four → Au + KOH + 3 / 4NaOH
+ 3 / 4H Three BO Three + 3 / 2H 2 ↑
Here, when the above sodium borohydride is used as the reducing agent, the concentration of the electrolyte generated by the reduction reaction increases as can be confirmed from the above reaction formula, and the fine particles are likely to aggregate as described later, and added as a reducing agent. Since the amount is limited, there is an inconvenience that the silver concentration in the colloidal dispersion of silver fine particles to be used cannot be increased.
[0034]
On the other hand, when the hydrazine is used as a reducing agent, it is more suitable as a reducing agent because the electrolyte generated by the reduction reaction is small as can be confirmed from the above reaction formula.
[0035]
In addition, as a gold coating raw material, a salt other than an alkali metal gold salt, such as chloroauric acid (HAuCl Four ) Or chloroaurate (NaAuCl) Four , KAuCl Four Etc.), the reduction reaction with hydrazine is shown as follows.
[0036]
XAuCl Four + 3 / 4N 2 H Four → Au + XCl + 3HCl + 3 / 4N 2 ↑
(X = H, Na, K, etc.)
When chloroauric acid or the like is applied in this manner, the concentration of the electrolyte due to the reduction reaction is increased as compared with the case of using the aurate, and chlorine ions are generated. Since soluble silver chloride is produced | generated, it is difficult to use for the raw material of the coating liquid for transparent conductive layer formation concerning this invention.
[0037]
Next, a colloidal dispersion of gold-coated silver fine particles in which a compound having a mercapto group, a sulfide group or a disulfide group is bonded to the surface of the coating layer or covered with this compound is then subjected to dialysis, electrodialysis, ion exchange, It is preferable to lower the electrolyte concentration in the dispersion by a desalting method such as ultrafiltration. This is because colloids generally aggregate in the electrolyte unless the electrolyte concentration is lowered, and this phenomenon is also known as the Schulze-Hardy law.
[0038]
Subsequently, the colloidal dispersion of the gold-coated silver fine particles subjected to the desalting treatment is concentrated by a method such as a vacuum evaporator, ultrafiltration or the like, and a compound having a mercapto group, a sulfide group or a disulfide group is bound thereto. A dispersion concentrate of the gold-coated silver fine particles covered with this compound is obtained, and the mixture of the gold-coated silver fine particles is mixed with a solvent alone or a solvent containing an inorganic binder to adjust the components (fine particle concentration, moisture content). The transparent conductive layer forming coating liquid according to the present invention to which the gold-coated silver fine particles are applied as the metal fine particles is obtained.
[0039]
Here, when ultrafiltration is applied as a desalination treatment method, the ultrafiltration also acts as a concentration treatment as described above, and therefore, the desalination treatment and the concentration treatment can be performed simultaneously. . The solvent may be substituted with a solvent contained in the dispersion concentrate of gold-coated silver fine particles (that is, the use of the solvent alone may be omitted). Further, the inorganic binder may be additionally mixed in a state where it is contained in a dispersion concentrate or a solvent of gold-coated silver fine particles, or the inorganic binder may be additionally mixed as it is, and the mixing method is arbitrary. is there. Moreover, there is no restriction | limiting in particular as said solvent, According to the coating method and film forming conditions, it selects suitably. For example, alcohol solvents such as methanol, ethanol, isopropanol, butanol, benzyl alcohol, diacetone alcohol (DAA), ketone solvents such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclohexanone, isophorone, propylene glycol Glycol derivatives such as methyl ether, propylene glycol ethyl ether, formamide, N-methylformamide, dimethylformamide (DMF), dimethylacetamide, dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), etc. Although it is mentioned, it is not limited to these.
[0041]
Next, using the thus obtained coating liquid for forming a transparent conductive layer according to the present invention, a transparent substrate and a mercapto group, sulfide group or disulfide group formed on the transparent substrate and having a surface thereof A transparent conductive layer mainly composed of gold-containing noble metal fine particles such as gold-silver binary noble metal fine particles having an average particle diameter of 1 to 100 nm and bonded with the compound and covered with the compound, and a binder matrix as a main component is formed thereon. A transparent conductive substrate, the main part of which is composed of a transparent two-layer film composed of a transparent coating layer, can be obtained.
[0042]
And in order to form the said transparent double layer film | membrane on a transparent substrate, this can be performed with the following method. That is, a solvent, a gold-containing noble metal fine particle such as a gold-coated silver fine particle having an average particle diameter of 1 to 100 nm, a compound having a mercapto group, a sulfide group, or a disulfide group (this compound and the gold-containing noble metal fine particle react to react as described above. The surface of the gold-containing noble metal fine particles is covered with the above compound), and the coating liquid for forming a transparent conductive layer according to the present invention is spray-coated, spin-coated on a transparent substrate such as a glass substrate or a plastic substrate. After coating by a method such as wire bar coating or doctor blade coating and drying as necessary, a coating solution for forming a transparent coat layer mainly composed of silica sol or the like is overcoated by the above-described method. Next, after overcoating, for example, a heat treatment is performed at a temperature of about 50 to 350 ° C. to cure the overcoated coating liquid for forming a transparent coat layer, thereby forming the transparent two-layer film. In the heat treatment at about 50 to 350 ° C., the gold-containing noble metal fine particles such as the gold-silver two-component noble metal fine particles are protected with gold, but no problem occurs. However, the silver fine particles exceeded 200 ° C. In some cases, the surface resistance increases due to oxidative diffusion, and the film deteriorates.
[0043]
Here, when a transparent conductive layer is formed using the coating liquid for forming a transparent conductive layer according to the present invention in which a compound having a mercapto group, a sulfide group or a disulfide group is blended, the above-mentioned compound is not included. Compared with the case where the coating liquid for forming the conductive layer is applied, the network structure of the gold-containing noble metal fine particles has been developed, which greatly contributes to the improvement of the film conductivity in the high transmittance region.
[0044]
In addition, since the contact area between the transparent substrate and the binder matrix such as silicon oxide increases through the hole portion of the network structure in the gold-containing noble metal fine particles, the bond between the transparent substrate and the binder matrix becomes strong, and the film in the transparent conductive layer Strength can be improved.
[0045]
Further, a compound having a mercapto group, a sulfide group or a disulfide group, which is relatively firmly bonded to the gold-containing noble metal fine particles when the coating solution for forming a transparent coating layer mainly composed of silica sol is overcoated by the above-described method. The functional group of the above and the silica sol interact with each other, and the gold-containing noble metal fine particles can be bonded to the silica sol through the compound, so that the film strength and weather resistance of the transparent conductive layer can be improved.
[0046]
The silica sol is a polymer obtained by adding water or an acid catalyst to orthoalkyl silicate and hydrolyzing it, and dehydrating polycondensation, or a commercially available polymer that has already been hydrolyzed to 4-5 mer. A polymer obtained by further proceeding hydrolysis and dehydration condensation polymerization of the alkylsilicate solution can be used. Also, as dehydration condensation polymerization proceeds, the solution viscosity increases and eventually solidifies, so the degree of dehydration condensation polymerization is less than the upper limit viscosity that can be applied on a transparent substrate such as a glass substrate or a plastic substrate. Adjust to. However, the degree of dehydration condensation polymerization is not particularly specified as long as it is a level equal to or lower than the above upper limit viscosity, but in view of film strength, weather resistance and the like, a weight average molecular weight of about 500 to 3000 is preferable. The alkyl silicate partially hydrolyzed polymer almost completes the dehydration condensation polymerization reaction when the transparent two-layer film is heated and fired, and becomes a hard silicate film (a film containing silicon oxide as a main component). It is also possible to change the reflectance of the transparent two-layer film by adding magnesium fluoride fine particles, alumina sol, titania sol, zirconia sol or the like to the silica sol to adjust the refractive index of the transparent coating layer.
[0047]
As described above, the transparent conductive layer (the transparent conductive layer formed by applying the coating liquid for forming a transparent conductive layer according to the present invention ( Claim 4 ) Transparent conductive substrate ( Claim 5 ) Has a higher transmittance and better mechanical strength than before, and has various properties such as low resistance, low reflectance, weather resistance, and UV resistance, as well as an excellent transmitted light profile in the visible light range. For example, on the above-described front plate in display devices such as cathode ray tube (CRT), plasma display panel (PDP), fluorescent display tube (VFD), field emission display (FED), electroluminescence display (ELD), liquid crystal display (LCD), etc. Can be used.
[0048]
【Example】
Examples of the present invention will be specifically described below, but the present invention is not limited to these examples. Further, “%” in the text indicates “% by weight” excluding (%) of transmittance, reflectance, and haze value, and “part” indicates “part by weight”.
[0049]
[Example 1]
A colloidal dispersion of silver fine particles was prepared by the aforementioned Carey-Lea method.
[0050]
Specifically, after adding a mixed solution of 39 g of 23% iron (II) sulfate solution and 48 g of 37.5% sodium citrate aqueous solution to 33 g of 9% silver nitrate aqueous solution, the precipitate was filtered and washed, and then purified water Was added to prepare a colloidal dispersion of silver fine particles (Ag: 0.15%). To 80 g of the colloidal dispersion of silver fine particles, hydrazine monohydrate (N 2 H Four ・ H 2 While adding 10.0 g of 1% aqueous solution of O) and stirring, potassium metalate [KAu (OH) Four A mixed solution of 320 g of an aqueous solution (Au: 0.15%) and 0.6 g of a 1% aqueous thiomalic acid solution was added to obtain a colloidal dispersion of gold-coated silver fine particles covered with thiomalic acid.
[0051]
After desalting the colloidal dispersion of gold-coated silver fine particles covered with thiomalic acid with an ion exchange resin (trade name Diaion SK1B, SA20AP manufactured by Mitsubishi Chemical Corporation), ethanol (EA) and a solution concentrated by ultrafiltration Diacetone alcohol (DAA) was added, and the transparent conductive layer forming coating solution according to Example 1 containing gold-coated silver fine particles covered with thiomalic acid (Ag: 0.06%, Au: 0.25%, Thiomalic acid: 0.003%, water: 9.7%, DAA: 10.0%, EA: 79.9%). As a result of observing the obtained coating liquid for forming a transparent conductive layer according to Example 1 with a transmission electron microscope, the average particle diameter of the gold-coated silver fine particles covered with thiomalic acid was 7.8 nm.
[0052]
Next, the transparent conductive layer forming coating liquid according to Example 1 was spin-coated (150 rpm, 60 seconds) on a glass substrate (3 mm thick soda lime glass) heated to 35 ° C., and then continued. Then, a coating solution for forming a transparent coating layer composed of a silica sol solution is spin-coated (150 rpm, 60 seconds), and further cured at 200 ° C. for 20 minutes to obtain gold-silver binary noble metal fine particles covered with thiomalic acid. A transparent conductive substrate according to Example 1 was obtained, that is, a glass substrate with a transparent two-layer film composed of a transparent conductive layer having a transparent coating layer composed of a silicate film composed mainly of silicon oxide.
[0053]
In addition, when the heat treatment at 200 ° C. for 20 minutes is performed, there is a possibility that an alloyed layer is formed by thermal diffusion of gold and silver in the gold-coated silver fine particles. There are cases where it is not necessarily composed of gold alone. For this reason, in this specification, even when gold-coated silver fine particles are applied in the coating liquid for forming a transparent conductive layer, the fine particles in the transparent conductive layer composed of gold and silver Instead of expressing as fine particles, it is expressed as gold-silver two-component noble metal fine particles as described above.
[0054]
Here, the silica sol solution is composed of 19.6 parts of methyl silicate 51 (trade name, manufactured by Colcoat Co.), 57.8 parts of ethanol, 7.9 parts of 1% nitric acid aqueous solution, and 14.7 parts of pure water. 2 (Silicon oxide) A solid content concentration of 10% and a weight average molecular weight of 2850 were prepared. 2 It is obtained by diluting with a mixture (IPA / NBA = 3/1) of isopropyl alcohol (IPA) and n-butanol (NBA) so that the solid content concentration becomes 0.8%.
[0055]
The film properties (surface resistance, visible light transmittance, transmittance standard deviation, haze value, bottom reflectance / bottom wavelength) of the transparent two-layer film formed on the glass substrate are shown in Table 1 below.
[0056]
The bottom reflectance means a minimum reflectance in the reflection profile of the transparent conductive substrate, and the bottom wavelength means a wavelength at which the reflectance is a minimum.
[0057]
Moreover, the reflection profile of the manufactured transparent conductive substrate according to Example 1 is shown in FIG. 1, and the transmission profile is shown in FIG.
[0058]
Moreover, the transmittance | permeability of only the transparent bilayer film which does not contain the transparent substrate (glass substrate) of visible light wavelength range (380-780 nm) in Table 1 is calculated | required as follows.
[0059]
That is,
Transmittance (%) of transparent two-layer film only without transparent substrate
= [(Transmittance measured for each transparent substrate) / (Transparency of transparent substrate)] × 100
In the present specification, unless otherwise specified, the transmittance does not include a transparent substrate (that is, the transmittance of the transparent two-layer film).
[0060]
The surface resistance of the transparent two-layer film was measured using a surface resistance meter Loresta AP (MCP-T400) manufactured by Mitsubishi Chemical Corporation. The haze value and visible light transmittance were measured using a haze meter (HR-200) manufactured by Murakami Color Research Laboratory for each transparent substrate. The reflectance and the reflection / transmission profile were measured using a spectrophotometer (U-4000) manufactured by Hitachi, Ltd. The particle diameter of the gold-coated silver fine particles covered with thiomalic acid is evaluated with a transmission electron microscope manufactured by JEOL.
[0061]
[Example 2]
To the concentrated solution of the gold-coated silver fine particle colloidal dispersion covered with thiomalic acid prepared in Example 1, ethanol (EA), diacetone alcohol (DAA) and a tetramer of tetramethyl silicate as an inorganic binder (manufactured by Colcoat) A transparent conductive layer forming coating solution according to Example 2 (Ag: 0.06%) containing gold-coated silver fine particles with an average particle diameter of 7.8 nm covered with thiomalic acid, with the addition of trade name methyl silicate 51) , Au: 0.25%, thiomalic acid: 0.003%, SiO 2 : 0.01%, water: 9.7%, DAA: 10.0%, EA: 79.9%).
[0062]
And except having used the coating liquid for transparent conductive layer formation concerning this Example 2, it carries out similarly to Example 1, and the transparent conductive layer which has gold-silver two-component system noble metal fine particles covered with thiomalic acid, A glass substrate with a transparent two-layer film composed of a transparent coating layer composed of a silicate film containing silicon oxide as a main component, that is, a transparent conductive substrate according to Example 2 was obtained.
[0063]
The film properties of the transparent two-layer film formed on the glass substrate are shown in Table 1 below.
[0064]
[Example 3]
Using 80 g of a colloidal dispersion of silver fine particles prepared by the same method as in Example 1, and hydrazine monohydrate (N 2 H Four ・ H 2 7.0) of 1% aqueous solution of O), potassium goldate [KAu (OH) Four Using 240 g of an aqueous solution (Au: 0.15%) and 0.16 g of a 1% aqueous solution of sodium thiosalicylate, the same treatment as in Example 1 was performed, and gold having an average particle diameter of 9.1 nm covered with thiosalicylic acid Coating liquid for forming transparent conductive layer according to Example 3 containing coated silver fine particles (Ag: 0.08%, Au: 0.22%, thiosalicylic acid: 0.002%, water: 12.1%, DAA : 10.0%, EA: 77.4%).
[0065]
And it carried out similarly to Example 1 except having used the coating liquid for transparent conductive layer formation concerning this Example 3, and the transparent conductive layer which has gold-silver two-component system noble metal fine particles covered with thiosalicylic acid, A glass substrate with a transparent two-layer film composed of a transparent coating layer composed of a silicate film containing silicon oxide as a main component, that is, a transparent conductive substrate according to Example 3 was obtained.
[0066]
The film properties of the transparent two-layer film formed on the glass substrate are shown in Table 1 below.
[0067]
[Example 4]
Using 80 g of a colloidal dispersion of silver fine particles prepared by the same method as in Example 1, and hydrazine monohydrate (N 2 H Four ・ H 2 10.0% of 1% aqueous solution of O), potassium metalate [KAu (OH) Four The average particle size covered with thiodiglycolic acid by using the same treatment as in Example 1 while using 320 g of an aqueous solution (Au: 0.15%) and 1.2 g of a 1% aqueous solution of thiodiglycolic acid. Transparent conductive layer forming coating solution according to Example 4 containing 8 nm gold-coated silver fine particles (Ag: 0.06%, Au: 0.24%, thiodiglycolic acid: 0.006%, water: 10 2%, DAA: 10.0%, EA: 79.4%).
[0068]
And the transparent conductive layer which carried out similarly to Example 1 except having used the coating liquid for transparent conductive layer formation which concerns on this Example 4, and has the gold-silver two-component system noble metal microparticles | fine-particles covered with thiodiglycolic acid. And a glass substrate with a transparent two-layer film composed of a silicate film mainly composed of silicon oxide, that is, a transparent conductive substrate according to Example 4 was obtained.
[0069]
The film properties of the transparent two-layer film formed on the glass substrate are shown in Table 1 below.
[0070]
[Example 5]
Using 80 g of a colloidal dispersion of silver fine particles prepared by the same method as in Example 1, and hydrazine monohydrate (N 2 H Four ・ H 2 10.0% of 1% aqueous solution of O), potassium metalate [KAu (OH) Four The average particle size covered with dithiodiglycolic acid by using the same treatment as in Example 1 while using 320 g of an aqueous solution (Au: 0.15%) and 0.2 g of a 1% aqueous solution of dithiodiglycolic acid. Transparent conductive layer forming coating solution according to Example 5 containing 1 nm of gold-coated silver fine particles (Ag: 0.05%, Au: 0.23%, dithiodiglycolic acid: 0.001%, water: 9 .3%, DAA: 10.0%, EA: 80.3%).
[0071]
And the transparent conductive layer which carried out similarly to Example 1 except having used the coating liquid for transparent conductive layer formation which concerns on this Example 5, and has gold-silver two-component system noble metal microparticles | fine-particles covered with dithiodiglycolic acid. A glass substrate with a transparent two-layer film composed of a silicate film composed mainly of silicon oxide and a transparent conductive substrate according to Example 5 was obtained.
[0072]
The film properties of the transparent two-layer film formed on the glass substrate are shown in Table 1 below.
[0073]
[Example 6]
Using 80 g of a colloidal dispersion of silver fine particles prepared by the same method as in Example 1, and hydrazine monohydrate (N 2 H Four ・ H 2 10.0% of 1% aqueous solution of O), potassium metalate [KAu (OH) Four Using 320 g of an aqueous solution (Au: 0.15%) and 0.6 g of a 1% aqueous solution of γ-mercaptopropyltrimethoxysilane, the same treatment as in Example 1 was performed to obtain γ-mercaptopropyltrimethoxysilane (actually The methoxy group was hydrolyzed in the coating solution to form a silanol group [Si—OH]), and the gold-coated silver fine particles having an average particle diameter of 8.3 nm were covered. Coating liquid for forming a conductive layer (Ag: 0.06%, Au: 0.23%, γ-mercaptopropyltrimethoxysilane: 0.003%, water: 8.6%, DAA: 10.0%, EA: 81.0%).
[0074]
And it carried out similarly to Example 1 except having used the coating liquid for transparent conductive layer formation concerning this Example 6, and has the gold-silver two-component system noble metal fine particle covered with (gamma) -mercaptopropyl trimethoxysilane. A glass substrate with a transparent two-layer film composed of a transparent conductive layer and a transparent coat layer composed of a silicate film containing silicon oxide as a main component, that is, a transparent conductive substrate according to Example 6 was obtained.
[0075]
The film properties of the transparent two-layer film formed on the glass substrate are shown in Table 1 below.
[0076]
[Comparative example]
Using 80 g of a colloidal dispersion of silver fine particles prepared by the same method as in Example 1, and hydrazine monohydrate (N 2 H Four ・ H 2 7.0) of 1% aqueous solution of O), potassium goldate [KAu (OH) Four Using 240 g of an aqueous solution (Au: 0.15%) and 0.48 g of a 1% polymer dispersant aqueous solution, the same treatment as in Example 1 was performed to disperse gold-coated silver fine particles having an average particle diameter of 8.3 nm. The transparent conductive layer forming coating solution (Ag: 0.08%, Au: 0.23%, water: 12.0%, DAA: 10.0%, EA: 77.9%) according to the comparative example was obtained. It was.
[0077]
And it carries out similarly to Example 1 except having used the coating liquid for transparent conductive layer formation which concerns on this comparative example, and has as a main component a transparent conductive layer which has gold-silver two-component system noble metal microparticles, and a silicon oxide. A glass substrate with a transparent two-layer film composed of a transparent coat layer made of a silicate film, that is, a transparent conductive substrate according to a comparative example was obtained.
[0078]
The film properties of the transparent two-layer film formed on the glass substrate are shown in Table 1 below.
[0079]
[Table 1]
The transparent conductive substrate according to Examples 1 to 6 and the transparent conductive substrate according to the comparative example were allowed to stand for 3 months under conditions exposed to direct sunlight outdoors, and were provided on a transparent substrate (glass substrate). The surface resistance value and appearance of the two-layer film were examined. The results are shown in Table 2 below.
[0080]
[Table 2]
About the transparent conductive base material which concerns on Examples 1-6 and the transparent conductive base material which concerns on a comparative example, the eraser test (Namely, the film | membrane surface of each transparent conductive base material is 50 reciprocations on condition of 1 kg of load with an eraser, and 100 A test for observing and evaluating scratches on the surface of the film was continued and the film strength of the transparent two-layer film provided on the transparent substrate (glass substrate) was examined.
[0081]
The results are shown in Table 3 below.
[0082]
[Table 3]
1. As is clear from the results shown in Table 1, the surface resistance of the transparent two-layer film according to each example is in the range of 648 to 925 Ω / □, and the visible light transmittance of the transparent two-layer film is also 86. Since it is in the range of 7 to 87.5%, it can be confirmed that the transparent two-layer film according to each Example has high transmittance and low resistance.
[0083]
On the other hand, the visible light transmittance of the transparent two-layer film according to the comparative example is 86.9% and has a high transmittance characteristic, but the surface resistance of the transparent two-layer film is as high as 2253 Ω / □ and low resistance. It can be confirmed that the characteristics are not provided.
[0084]
2. Further, as apparent from the results shown in Table 2, the appearance of the transparent two-layer film according to each example has not changed, and the initial value of the manifestation resistance in the transparent two-layer film and the outdoor standing for three months The value does not change much. Therefore, it can be confirmed that the weather resistance of the transparent two-layer film according to each example has sufficient characteristics.
[0085]
On the other hand, the appearance of the transparent two-layer film according to the comparative example has not changed, but the value is based on the initial value (2253Ω / □) of the manifestation resistance in the transparent two-layer film and the value of three months left outdoors (5795Ω / □). It has changed greatly and it can confirm that the weather resistance of the transparent two-layer film which concerns on a comparative example is inadequate.
[0086]
3. Furthermore, from the results of Table 3, the mechanical strength of the transparent two-layer film according to each example is sufficient as compared with the comparative example, and the mechanical strength of the transparent two-layer film in each example is sufficient. Can be confirmed.
[0087]
【The invention's effect】
According to the coating liquid for forming a transparent conductive layer according to claims 1 to 3,
High transmittance, excellent mechanical strength, low resistance, low reflectance, and weather resistance, and excellent transmitted light profile in the visible light range A transparent conductive layer according to the invention of
[Brief description of the drawings]
1 is a graph showing a reflection profile of a transparent conductive substrate according to Example 1. FIG.
2 is a graph showing a transmission profile of a transparent conductive substrate according to Example 1. FIG.
Claims (5)
上記金含有貴金属微粒子中の金成分１重量部に対して、メルカプト基、スルフィド基またはジスルフィド基を有する化合物が０．００４〜０．０２５重量部の割合で含まれていることを特徴とする透明導電層形成用塗液。A transparent conductive layer forming coating comprising, as a main component, a solvent and a gold-containing noble metal fine particle having an average particle diameter of 1 to 100 nm and containing 5 to 95% by weight of gold dispersed in the solvent, and forming a transparent conductive layer on a transparent substrate In the liquid
A transparent compound comprising a compound having a mercapto group, a sulfide group or a disulfide group in a proportion of 0.004 to 0.025 parts by weight with respect to 1 part by weight of the gold component in the gold-containing noble metal fine particles. Coating liquid for forming a conductive layer.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000041887A JP3750461B2 (en) | 2000-02-18 | 2000-02-18 | Transparent conductive layer forming coating liquid, transparent conductive layer and transparent conductive substrate |
| DE60023614T DE60023614T2 (en) | 1999-08-26 | 2000-08-24 | Transparent electrolytic structure and process for its preparation, coating fluid therefor and display device having this structure |
| EP00118392A EP1079413B1 (en) | 1999-08-26 | 2000-08-24 | Transparent conductive layered structure and method of producing the same, coating liquid useful therefor, and display that uses transparent conductive layered structure |
| TW089117190A TWI235757B (en) | 1999-08-26 | 2000-08-25 | Transparent conductive layered structure and method of producing the same, coating liquid for forming transparent coating layer and coating liquid for foaming transparent conductive layer used in the production of transparent conductive layered structure |
| KR1020000049855A KR100737923B1 (en) | 1999-08-26 | 2000-08-26 | Transparent conductive layered structure and method of producing the same, coating liquid for forming transparent coating layer and coating liquid for forming transparent conductive layer used in the production of transparent conductive layered structure, and display that uses transparent conductive layered structure |
| US10/329,573 US6716480B2 (en) | 1999-08-26 | 2002-12-27 | Transparent conductive layered structure and method of producing the same, coating liquid for forming transparent coating layer and coating liquid for forming transparent conductive layer |
| US10/330,278 US20030170448A1 (en) | 1999-08-26 | 2002-12-30 | Transparent conductive layered structure and method of producing the same, coating liquid for forming transparent coating layer and coating liquid for forming transparent conductive layer used in the production of transparent conductive layered structure, and display that uses transparent conductive layered structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000041887A JP3750461B2 (en) | 2000-02-18 | 2000-02-18 | Transparent conductive layer forming coating liquid, transparent conductive layer and transparent conductive substrate |
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| JP3750461B2 true JP3750461B2 (en) | 2006-03-01 |
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| JP2000041887A Expired - Fee Related JP3750461B2 (en) | 1999-08-26 | 2000-02-18 | Transparent conductive layer forming coating liquid, transparent conductive layer and transparent conductive substrate |
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| JP4024606B2 (en) * | 2002-07-05 | 2007-12-19 | 株式会社椿本チエイン | Water-dispersible zinc powder and water-based paint containing zinc powder |
| CN100587857C (en) * | 2003-09-08 | 2010-02-03 | 住友金属矿山株式会社 | Transparent conductive multilayer body, organic EL device using same, and methods for manufacturing same |
| EP2568778A4 (en) * | 2011-02-10 | 2015-07-08 | Sumitomo Riko Co Ltd | Flexible conductive material, method for manufacturing same, and electrode, wiring, electromagnetic wave shielding, and transducer using flexible conductive material |
| CN105764635B (en) * | 2013-09-24 | 2019-11-12 | 贺利氏德国有限两合公司 | The method of gloss laminar structure is manufactured at low temperature |
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