JP2004013451A - Input panel, film-like base material, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an input panel with improved characteristic such as transparency of the input panel as a whole, resolution, response characteristics, and product reliability by means of a simple and inexpensive manufacturing method for the transparent input panel arranged on a display part. <P>SOLUTION: In manufacturing the input panel, a transparent conductive film, a pressure-sensitive resin layer, and a resin layer including dispersed conductive particles are layered sequentially on a substrate, and then, the substrate having a transparent conductive film is overlaid on them so that the transparent conductive film is set on the inside. <P>COPYRIGHT: (C)2004,JPO

Description

〔式（Ｉ）中、
Ｒは、二価の芳香族炭化水素基又は二価の複素環含有芳香族基を示し、
Ｒ_１は、水素、アルキル基、フッ素化アルキル基、アルコキシ基又はハロゲンで、これは複数個（２〜４個）であってもよく、
Ｘは、Ｏ又はＮ−Ｒ_３（但し、Ｒ_３は次の基を示す。）を示し、
【化６】

ＹはＳＯ_２又はＣＯを示し、
ｎはポリマの繰返し単位の数、を示す。〕
また、本発明は，（３）前記導電性を有する微粒子を分散した樹脂層において、導電性を有する微粒子が球状であって、平均粒子径１〜１０μｍであり、その粒径分布が平均粒子径±０．３μｍの範囲である上記（１）または上記（２）に記載の入力パネルである。粒径分布は、本発明の目的から好ましくは、平均粒子径±０．２μｍであり、さらに好ましくは、平均粒子径±０．１μｍである。
また、本発明は，（４）前記導電性を有する微粒子を分散した樹脂層の膜厚をその微粒子の粒径と同じにしたことを特徴とする上記（１）ないし上記（３）のいずれかに記載の入力パネルである。
また、本発明は、（５）フィルム上に透明導電膜、導電性を有する微粒子を分散した樹脂層、感圧樹脂層を順次積層したフィルム状基材である。
また、本発明は、（６）フィルム上に透明導電膜、感圧樹脂層、導電性を有する微粒子を分散した樹脂層を順次積層したフィルム状基材である。
また、本発明は、（７）上記（５）または上記（６）に記載のフィルム状基材に、さらにカバーフィルムを貼り付けてなるフィルム状基材である。
また、本発明は、（８）前記感圧樹脂層が式Ｉで表されるポリフタリドを主成分とする樹脂層である上記（５）ないし上記（６）のいずれかに記載のフィルム状基材である。
【化７】

〔式（Ｉ）中、
Ｒは、二価の芳香族炭化水素基又は二価の複素環含有芳香族基を示し、
Ｒ_１は、水素、アルキル基、フッ素化アルキル基、アルコキシ基又はハロゲンで、これは複数個（２〜４個）であってもよく、
Ｘは、Ｏ又はＮ−Ｒ_３（但し、Ｒ_３は次の基を示す。）を示し、
【化８】

ＹはＳＯ_２又はＣＯを示し、
ｎはポリマの繰返し単位の数、を示す。〕。
また、本発明は，（９）上記（５）ないし上記（８）のいずれかに記載のフィルム状基材のカバーフィルムがある場合、これを剥離し、透明導電膜を有する基板上に貼り付けることによって、上記（１）ないし上記（４）のいずれかに記載の入力パネルを得る入力パネルの製造方法である。
【００１３】
【発明の実施の形態】
本発明の入力パネルの構成は、基板上に透明導電膜、感圧樹脂層、導電性を有する微粒子を分散した樹脂層を順次積層し、その上に透明導電膜を有する基板を透明導電膜が内側になるように積層した入力パネルである。図１は入力パネルの構成図である。図中、１及び６は基板、２及び５は透明導電膜、３は感圧樹脂層、４は導電性を有する微粒子を分散した樹脂層である。
本発明の入力パネルの構成における原理を図２に従って説明する。図２は本発明の断面図であり、圧力が伝えられる様子を示す。この入力パネルの表面に指やペンによる押し圧Ｐ１（ＭＰａ）を加えると、圧力は導電性を有する微粒子に集中し、感圧樹脂層に圧力Ｐ２として伝わる。１ｃｍ^２あたりｎ個の微粒子（直径ｄｃｍ）を配置したと仮定し、さらに簡単のため、微粒子が円柱状であると仮定すると、微粒子一つの接触面積は｛π×（ｄ／２）^２｝ｃｍ^２である。このとき、１個の微粒子にかかる圧力、すなわち感圧樹脂層にかかる圧力Ｐ２は下式で表される。実際には微粒子が球状であるのでこれ以上の圧力がかかることになる。
Ｐ２＝Ｐ１／｛π×（ｄ／２）^２×ｎ｝
指やペンによる圧力は軽いタッチが要求されており、この表面圧力Ｐ１の範囲は通常０．００５〜０．０２ＭＰａとするのが好ましい。
例えば、粒径５μｍの導電性を有する微粒子を１０００個／ｃｍ^２配置し、表面圧力Ｐ１に０．００５〜０．０２ＭＰａを加えたと仮定すると、感圧樹脂層に伝わる圧力Ｐ２は上式から２５〜１００ＭＰａと計算される
ここで、感圧樹脂層３が絶縁体から導電体へと変化する圧力しきい値は０．０３〜４．０ＭＰａであり、上記計算結果の感圧樹脂層に伝わる圧力Ｐ２で十分導電体へと変化することができる。
単位面積あたりの導電微粒子数ｎは多くすると透過率が悪くなり、少なくすると粒子間距離が長くなり位置検出の解像度が悪くなるので、５００〜１００００個／ｃｍ^２の範囲が好ましく、より好ましくは８００〜５０００個／ｃｍ^２、最も好ましいのは１０００〜２０００個／ｃｍ^２である。
【００１４】
以下、各構成要素を詳細に説明する。１及び６の基板の材質、厚さなどは特に限定するものではなく、その用途目的に応じてバリウムホウケイ酸ガラス、ソーダガラスなどの無機ガラスやポリエーテルスルホン（ＰＥＳ）、ポリスルホン（ＰＳＦ）、ポリカーボネート（ＰＣ）、ポリアリレート（ＰＡＲ）、ポリエチレンテレフタレート（ＰＥＴ）などの樹脂フィルム等のようなものの中から選ぶことが好ましい。２及び５の透明導電膜は透明で導電性を有する薄膜であれば特に限定するものではなく、従来のＩＴＯ（酸化インジウム錫）、ＡＴＯ（酸化アンチモン錫）等を使用することができる。
【００１５】
３の感圧樹脂層は通常は絶縁体であるが圧力を加えることによって導電体へと変化する樹脂組成物の膜である。感圧樹脂層は、具体的には、式（Ｉ）のポリフタリドが好ましく、これについて説明する。
式（Ｉ）で示したポリフタリド（以下総称してポリフタリドという）は、厚み方向に圧力を加えると、厚み方向の電気抵抗が大きく変化し導電性を発揮する特徴（感圧導電性）を有するものである。比較的低圧で相対的に加圧前後で、厚さ方向の電気抵抗が６桁以上の変化（通常は、大気圧で絶縁性を示し、加圧すると導電性を示す。）を発現させることが可能となる。
ここで、電気抵抗が６桁以上の変化とは、所定電圧の印加条件で測定するとき加圧前後で電気抵抗（又は電流）の変化が６桁以上になることを意味する。更に具体的には、所定電圧での電流値が１０^−１２Ａのオーダー（絶縁物）から１０^−６Ａオーダー以上の導電性物質に変化することを意味する。
ポリフタリドは、式Ｉで表される構造を有する。
【化９】

〔式（Ｉ）中、
Ｒは、二価の芳香族炭化水素基又は二価の複素環含有芳香族基を示し、
Ｒ_１は、水素、アルキル基、フッ素化アルキル基、アルコキシ基又はハロゲンで、これは複数個（２〜４個）であってもよく、
Ｘは、Ｏ又はＮ−Ｒ_３（但し、Ｒ_３は次の基を示す。）を示し、
【化１０】

ＹはＳＯ_２又はＣＯを示し、ｎはポリマの繰返し単位の数、を示す。〕
式（Ｉ）中のＲ（二価の芳香族炭化水素基又は二価の複素環含有芳香族基）としては、次の基などが挙げられる。
【化１１】

ここで、Ｒ_２は、前記Ｒ_１と同様で_、水素、アルキル基、フッ素化アルキル基、アルコキシ基又はハロゲン（フッ素や塩素など）で、これは複数個（２〜４個）であってもよい。
アルキル基、フッ素化アルキル基、アルコキシ基のアルキルとして、炭素数１〜２０のアルキル基、例えば、メチル基、エチル基、ｎ−プロピル基、イソプロピル基、ｎ−ブチル基、イソブチル基、ｓｅｃ−ブチル基、ｔｅｒｔ−ブチル基、ペンチル基、イソペンチル基、ネオペンチル基、ヘキシル基、ヘプチル基、オクチル基、ノニル基、デシル基、ウンデシル基、ドデシル基、トリデシル基、テトラデシル基、ペンタデシル基、ヘキサデシル基、ヘプタデシル基、オクタデシル基、ノナデシル基、イコシル基、これらの構造異性体等が挙げられる。また、フッ素化アルキルは、アルキル基の全部または一部がフッ素で置換されたものである。ハロゲンとしては、例えば、フッ素、塩素、臭素、ヨウ素、アスタチン等が挙げられる。
また、Ａｒ_１は、次の基などである。
【化１２】

また、Ａｒ_２は、次の基などである。
【化１３】

【００１６】
ポリフタリドは、単独重合物であっても、共重合物であっても、あるいは、これらのブレンド物であってもよい。
【００１７】
これらポリフタリド樹脂の屈折率は１．６〜１．８の範囲である。密着性を向上させる目的で、シランカップリング剤や他のポリマ、モノマを添加することもできる。また、感圧特性を改善するために、フタリドオリゴマーまたは電子供与性分子を添加しても良い。電子供与性分子としては、例えばテトラチアフルバレン、ビス（エチレンジチオロ）−テトラチアフルバレン、芳香族ジアミンなどが挙げられる。電子供与性分子は、ポリフタリド１００重量部に対し、１〜１０重量部配合することが好ましい。
【００１８】
４は導電性を有する微粒子を分散した樹脂層である。導電性を有する微粒子は透明導電膜と感圧樹脂層の電気的な導通をはかることと指やペンによって加えられた圧力を感圧樹脂層に伝えることを目的としている。パネル面全体で均一な圧力応答性を得るためには、粒径が単一でかつ粒径分布が平均粒子径の±０．３μｍ、好ましくは±０．２μｍ、さらに好ましくは±０．１μｍの均一な球状の微粒子であることが好ましく、導電性を有する微粒子を分散した樹脂層の膜厚は導電性微粒子の粒径とほぼ同等（±０．３ｍｍ）にしておくことが好ましい。また、導電性微粒子の粒径は１〜１０μｍの範囲のうちから選ばれるが、透過率向上の観点からこの樹脂層の膜厚はなるべく薄い方が良く、微粒子の粒径は３〜７μｍの範囲が最も好ましい。導電性を有する微粒子とは少なくとも表面に導電層があればよく、例えばニッケル、金、銀、銅などの金属微粒子のほか、絶縁性の無機微粒子や樹脂微粒子に金属メッキを施したもの等が使用できる。この導電性を有する微粒子を分散した樹脂層に使用される樹脂は透明で弾性を有するものであれば特に好ましく制限するものではないが、透過率の向上を図る目的から透明電極の屈折率に近い値である方が良い。例えば、ブチルゴム、ウレタンゴム、シリコンゴム、フッ素ゴム、ポリビニルアルコール、アクリル樹脂、ウレタン樹脂等の高分子樹脂があげられ、これら樹脂の屈折率は１．５〜１．７の範囲であると好ましい。
【００１９】
本発明の入力パネルを得るための製造方法としては透明導電膜付基板上に感圧樹脂層、導電性を有する微粒子を分散した樹脂層を順次スピンコート法等によって塗布、乾燥し、最後に透明導電膜付基板を貼り付ける事によって得られる他、後述の本発明のフィルム状基材のカバーフィルムを剥離し（カバーフィルムを設けた場合）、透明導電膜を有する基板上に貼り付けることによって得る方法がもっとも簡便かつ低コストな方法である。カバーフィルムとしては、化学的および熱的に安定で、感圧導電微粒子分散樹脂層との剥離が容易であるものが望ましい。具体的にはポリエチレン、ポリプロピレン、ポリエチレンテレフタレート、ポリビニルアルコール等の薄いシート状のもので表面の平滑性が高いものが好ましい。剥離性を付与するために表面に離型処理をしたものでも良い。
【００２０】
フィルム状基材を得る方法としては、ロール状透明導電膜付フィルムの上にダイコータ、コンマコータ、グラビアコータ等の塗工機によって導電性を有する微粒子を分散した樹脂層、感圧樹脂層を順次塗工し、最後に必要によりカバーフィルムを貼り付けて巻き取る、すなわちロール　トゥ　ロールで作製するのが最も簡便かつ低コストであり、大面積化への対応も行いやすい。
【００２１】
フィルム状基材を得るには上記した方法において、感圧樹脂層と導電性を有する微粒子を分散した樹脂層の順序を変えて塗工することによっても同様に得ることができる。
【００２２】
従来の入力パネルでは上下の透明導電膜（屈折率１．９）間に空隙層（屈折率１．０）がありその屈折率差が約０．９と大きいため、界面における反射率が大きく、パネル全体の透過率を低下させる大きな要因となっていた。しかし、本発明の入力パネルにおいては、上下の透明導電膜（屈折率１．９）間に感圧樹脂層（屈折率１．６〜１．８）と導電性を有する微粒子を分散した樹脂層（１．５〜１．７）を配置しているのでパネル全体の透過率は従来パネルに比べて大きく向上する。また、従来の上部電極をたわませて上下電極の接触を得る入力パネルと異なり、上部電極のたわみ量は極わずかであることから電極の剥離等による劣化はほとんどなく繰り返し使用に関わる製品信頼性が大幅に向上する。さらにスペーサレスであり、全面均一な応答性、解像度を得ることができる。
【００２３】
【実施例】
（実施例１）
下式で表されるポリ（４，４’−ジフェニレンメチルフタリド）をシクロヘキサノン
【化１４】

溶媒に溶解し１０ｗｔ％の感圧樹脂塗液を調整した。また、アクリルゴムをメチルエチルケトン溶媒に溶解し５ｗｔ％のアクリルゴム溶液を調整し、さらに平均粒子径５μｍ（±０．１μｍ）の粒径の球状導電性微粒子（ポリスチレン微粒子にＮｉ＋Ａｕメッキしたもの、製品名ミクロパール、積水ファインケミカル社製商品名）を０．０５ｗｔ％（全体に対して）分散して導電性微粒子分散樹脂塗液を得た。
ＩＴＯ透明導電膜（表面抵抗２００Ω／□）付ガラス基板上（厚み０．７ｍｍ）に上記感圧樹脂塗液をスピンコート法により塗布し、１００℃で乾燥した。この塗膜の膜厚は約１μｍになるように回転数を調整した。次に上記球状導電性微粒子を分散したアクリルゴム塗液をスピンコート法により塗布し、１００℃で乾燥した。このとき、塗膜の膜厚が約５μｍになるように回転数を調整した。最後にＩＴＯ透明導電膜付のＰＥＴフィルム（厚み１２５μｍ）を膜面が内側になるようにラミネート法により貼り付けた。以上の操作によって、入力パネルを得ることができた。この入力パネルのＰＥＴ側電極、ガラス基板側電極間に５Ｖの電圧を印可した。常圧下では抵抗１０^１４Ω・ｃｍの絶縁性を示すが、入力パネルの表面に０．０１５ＭＰａの圧力をかけると抵抗１０^３Ω・ｃｍの導電性を示した。
【００２４】
（実施例２）
ロール状に巻かれたＩＴＯ透明導電膜付ＰＥＴフィルム（厚み１２５μｍ）の膜面側に実施例１に記載の球状微粒子を分散したアクリルゴム塗液をコンマコータによって塗工した。次に実施例１に記載の感圧樹脂塗液をダイコータによって塗工し、ＰＥ（ポリエチレン、厚み２３μｍ）のカバーフィルムを塗工面に貼り付けながら巻き取った。塗工に際し、ＩＴＯ透明電極膜の両端は電極取り出し位置として塗工しない部分を設けた。以上の操作によってフィルム状基材を得ることができた。次にラミネート法によって、このフィルム基材をＩＴＯ透明導電膜付ガラス基板上（厚み０．７ｍｍ）にカバーフィルムを剥離しながら貼り付けた。
以上の操作によって、入力パネルを得ることができた。この入力パネルのＰＥＴ側電極、ガラス基板側電極間に５Ｖの電圧を印可した。常圧下では抵抗１０^１４Ω・ｃｍの絶縁性を示すが、入力パネルの表面に０．０１５ＭＰａの圧力をかけると抵抗１０^３Ω・ｃｍの導電性を示した。
【００２５】
（実施例３）
下式で表されるポリ（４，４’−ジフェニレンフタリド）をシクロヘキサノン溶媒
【化１５】

に溶解し１０ｗｔ％の感圧樹脂塗液を調整した。
ロール状に巻かれたＩＴＯ透明導電膜付ＰＥＴフィルム（厚み１２５μｍ）の膜面側に上記感圧導電樹脂及び実施例１に記載の球状微粒子を分散したアクリル樹脂を順次ダイコータによって塗工し、ＰＥ（ポリエチレン、厚さ２３μｍ）のカバーフィルムを塗工面に貼り付けながら巻き取った。塗工に際し、ＩＴＯ透明電極膜の両端は電極取り出し位置として塗工しない部分を設けた。以上の操作によってフィルム状基材を得ることができた。次にラミネート法によって、このフィルム状基材をＩＴＯ透明導電膜付ガラス基板上にカバーフィルムを剥離しながら貼り付けた。
以上の操作によって、入力パネルを得ることができた。この入力パネルのＰＥＴ側電極、ガラス基板側電極間に５Ｖの電圧を印可した。常圧下では抵抗１０^１４Ω・ｃｍの絶縁性を示すが、入力パネルの表面に０．０１５ＭＰａの圧力をかけると抵抗１０^３Ω・ｃｍの導電性を示した。
【００２６】
（実施例４）
下式で表されるポリ（４，４’−ジフェニレンスルホフタリド）をシクロヘキサノン
【化１６】

溶媒に溶解し１０ｗｔ％の感圧樹脂塗液を調整した。
ロール状に巻かれたＩＴＯ透明導電膜付ＰＥＴフィルム（厚み１２５μｍ）の膜面側に上記感圧導電樹脂及び実施例１に記載の球状微粒子を分散したアクリル樹脂を順次ダイコータによって塗工し、ＰＥ（ポリエチレン、厚み２３μｍ）のカバーフィルムを塗工面に貼り付けながら巻き取った。塗工に際し、ＩＴＯ透明電極膜の両端は電極取り出し位置として塗工しない部分を設けた。以上の操作によってフィルム状基材を得ることができた。次にラミネート法によって、このフィルム基材をＩＴＯ透明導電膜付ガラス基板上（厚み０．７ｍｍ）にカバーフィルムを剥離しながら貼り付けた。
以上の操作によって、入力パネルを得ることができた。この入力パネルのＰＥＴ側電極、ガラス基板側電極間に５Ｖの電圧を印可した。常圧下では抵抗１０^{１ ４}Ω・ｃｍの絶縁性を示すが、入力パネルの表面に０．０１５ＭＰａの圧力をかけると抵抗１０^３Ω・ｃｍの導電性を示した。
【００２７】
【発明の効果】
以上説明したように、本発明の入力パネルによれば従来の入力パネルよりもパネル全体の透過率が高く、製品信頼性の高い、スペーサレスな入力パネルを提供することができる。
また、本発明のフィルム状基材を使用することによって簡便かつ低コストに上記した入力パネルを作製することが可能となる。
【図面の簡単な説明】
【図１】本発明の入力パネルの構成図である。
【図２】本発明の入力パネルに圧力が伝わる様子を示した図である。
【符号の説明】
１　基板
２　透明導電膜
３　感圧樹脂層
４　導電性微粒子を分散した樹脂層
５　透明導電膜
６　基板[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an input panel for detecting a position pressed by a finger, a pen or the like and inputting the input position information to another information processing device, a film-like base material used for manufacturing the input panel, and a method for manufacturing an input panel.
[0002]
[Prior art]
For the input panel, for example, a transparent panel is provided in front of a display element such as an LCD (Liquid Crystal Display), PDP, digital paper, etc., and is suitably used for a transparent touch panel for inputting coordinates from the panel surface with a pen or a finger. Can be. The transparent touch panel can be operated according to the display content of the display element on the back side of the panel, and is therefore widely used in electronic notebooks, personal computers, POS terminals, and the like. In the future, with the adoption of broadband, it is expected that applications for selecting functions from display contents and for performing handwriting input in televisions, home appliances, digital papers, and the like will rapidly expand.
[0003]
Since such a transparent input panel is disposed in front of a display element such as a liquid crystal display device, a panel having a high transmittance is desired so as not to impair the image quality of the rear display element. Further, in recent years, display elements have become higher definition, and it is desired that input panels have higher resolution.
[0004]
Various types of transparent touch panels, such as a resistive type, a capacitive coupling type, an optical type, an ultrasonic type, and an electromagnetic induction type, have been developed, and each type is used for a suitable application depending on its features. In recent years, a resistive film method and a capacitive coupling method, which are easy to realize demands for thinner and lighter weight, have become the mainstream, and among them, the resistive film method has become mainstream due to a demand for cost reduction.
[0005]
The resistive film system is composed of two transparent substrates which face each other in parallel and have a transparent electrode on each inner surface thereof. A gap layer is provided at regular intervals between the transparent electrodes on the two substrates to ensure an electrical non-contact state, and a spacer is usually arranged to avoid contact due to bending. When pressure is applied from outside to this with a finger or pen, only the part to which pressure is applied comes into contact, and the other parts are brought into a non-contact state. The basic principle is that this difference is extracted as an electric signal from a terminal drawn out from each of the two transparent electrodes to the outside, and given to information equipment as position information.
[0006]
The advantages of this method are that it is thin and easy to lighten, its structure is simple and its manufacturing cost is low, it does not require special parts such as a special pen as an external contact body, The object is applicable.
[0007]
On the other hand, a problem of this method is that a gap layer (refractive index: 1) is sandwiched between upper and lower transparent electrodes (generally indium tin oxide, hereinafter ITO, refractive index: 1.9), and the refractive index difference is large. Therefore, the reflection at the interface becomes large and the transmittance becomes low as a result, the resolution of the contact position detection is low due to the inability to contact the spacer arrangement part, the response speed is low, the transparent electrode of the pressing part Is likely to be deteriorated during repeated deformation and contact, so that the product reliability is relatively lower than other methods.
[0008]
To improve these problems, various improvements have been proposed in the patent publication. Japanese Patent Application Laid-Open No. 2-1517 discloses a touch panel switch having a structure in which a gel-like insulating layer having shape resilience is interposed between upper and lower transparent electrodes.
The configuration described in JP-A-2-151916 is a transparent input device having a structure in which transparent insulating oil is sealed between upper and lower substrates.
In these methods, since a fluid having a higher refractive index than air is sealed without gaps in the gap layer between the electrodes, the reflectance at each interface can be reduced, that is, the transmittance can be improved. However, in such a configuration, it is necessary to spread the fluid by the pressing force to contact the upper and lower electrodes, so it is difficult to obtain a response with a light touch, and the time to return to the original state is longer than in the case of the gap layer That is, there is a problem that the response speed is reduced. In addition, since it is necessary to seal so that the fluid does not leak, the manufacturing process becomes complicated.
[0009]
Japanese Patent Application Laid-Open No. 61-243622 discloses a touch panel having a structure in which an elastic body mixed with tin oxide or indium oxide or a composite oxide thereof is interposed between upper and lower transparent electrodes. This is to obtain conductivity by improving the apparent fine particle density by deforming.
In this method as well, since an elastic body having a higher refractive index than air is sealed without gaps in the gap layer between the electrodes, the reflectance at each interface can be reduced, that is, the transmittance can be improved. However, in such a configuration, a strong pressing force is required to obtain sufficient conduction between the upper and lower electrodes, so that it is difficult to obtain a response with a light touch, and the time required to return to the original state is due to a gap layer. There is a problem that the response time becomes longer, that is, the response speed becomes slower.
[0010]
[Problems to be solved by the invention]
As described above, the conventional resistive film method has a structure in which a gap layer (refractive index 1) is sandwiched between upper and lower transparent electrodes (generally indium tin oxide, refractive index 1.9), and the difference in refractive index is large. , Reflection at the interface increases, resulting in lower transmittance, no contact at the spacer placement part, low resolution in detecting the contact position, low response speed, the transparent electrode of the pressing part repeatedly deformed However, there is a problem that the product reliability is relatively lower than other methods because the electrode is easily deteriorated, such as the electrode peeling off during contact.Examples in which all of these problems can be satisfactorily improved in the improved example There is no present.
[0011]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a transparent input panel with improved transmittance, resolution, response speed, and product reliability as described above.
[0012]
[Means for Solving the Problems]
According to the present invention, (1) a transparent conductive film, a pressure-sensitive resin layer, and a resin layer in which fine particles having conductivity are dispersed are sequentially laminated on a substrate, and the substrate having the transparent conductive film is placed on top of the transparent conductive film. It is an input panel laminated so that it becomes.
The present invention also provides (2) the input panel according to (1), wherein the pressure-sensitive resin layer is a resin layer containing polyphthalide represented by Formula I as a main component.
Embedded image

[In the formula (I),
R represents a divalent aromatic hydrocarbon group or a divalent heterocyclic-containing aromatic group,
R ₁ is hydrogen, an alkyl group, a fluorinated alkyl group, an alkoxy group or a halogen, which may be plural (2 to 4);
X represents O or N—R ₃ (where R ₃ represents the following group);
Embedded image

Y represents SO ₂ or CO,
n indicates the number of repeating units of the polymer. ]
The present invention also provides (3) the resin layer in which the conductive fine particles are dispersed, wherein the conductive fine particles are spherical, have an average particle diameter of 1 to 10 μm, and have a particle diameter distribution of the average particle diameter. The input panel according to the above (1) or (2), which has a range of ± 0.3 μm. For the purpose of the present invention, the particle size distribution is preferably an average particle size ± 0.2 μm, and more preferably an average particle size ± 0.1 μm.
Further, according to the present invention, (4) the resin layer in which the conductive fine particles are dispersed may have the same thickness as that of the fine particles. It is an input panel described in.
Further, the present invention is (5) a film-shaped substrate in which a transparent conductive film, a resin layer in which fine particles having conductivity are dispersed, and a pressure-sensitive resin layer are sequentially laminated on a film.
Further, the present invention is (6) a film-like substrate in which a transparent conductive film, a pressure-sensitive resin layer, and a resin layer in which conductive fine particles are dispersed are sequentially laminated on a film.
Further, the present invention is (7) a film-like substrate obtained by further attaching a cover film to the film-like substrate according to the above (5) or (6).
The present invention also provides (8) the film-like substrate according to any one of the above (5) to (6), wherein the pressure-sensitive resin layer is a resin layer containing a polyphthalide represented by the formula I as a main component. It is.
Embedded image

[In the formula (I),
R represents a divalent aromatic hydrocarbon group or a divalent heterocyclic-containing aromatic group,
R ₁ is hydrogen, an alkyl group, a fluorinated alkyl group, an alkoxy group or a halogen, which may be plural (2 to 4);
X represents O or N—R ₃ (where R ₃ represents the following group);
Embedded image

Y represents SO ₂ or CO,
n indicates the number of repeating units of the polymer. ].
Further, according to the present invention, (9) in the case where there is a cover film of a film-like substrate according to any one of the above (5) to (8), the cover film is peeled off and attached on a substrate having a transparent conductive film. Accordingly, a method of manufacturing an input panel for obtaining the input panel according to any one of the above (1) to (4).
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The configuration of the input panel of the present invention is such that a transparent conductive film, a pressure-sensitive resin layer, and a resin layer in which conductive fine particles are dispersed are sequentially laminated on a substrate, and the substrate having the transparent conductive film is formed on the substrate. This is an input panel stacked so as to be on the inside. FIG. 1 is a configuration diagram of the input panel. In the figures, 1 and 6 are substrates, 2 and 5 are transparent conductive films, 3 is a pressure-sensitive resin layer, and 4 is a resin layer in which conductive fine particles are dispersed.
The principle of the configuration of the input panel of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view of the present invention, showing how pressure is transmitted. When a pressing force P1 (MPa) with a finger or a pen is applied to the surface of the input panel, the pressure is concentrated on the conductive fine particles and transmitted to the pressure-sensitive resin layer as the pressure P2. Assuming that n fine particles (diameter dcm) are arranged per 1 cm ² , and for simplicity, assuming that the fine particles are columnar, the contact area of one fine particle is {π × (d / 2) ² } cm ² . At this time, the pressure applied to one fine particle, that is, the pressure P2 applied to the pressure-sensitive resin layer is expressed by the following equation. Actually, since the fine particles are spherical, more pressure is applied.
P2 = P1 / {π × (d / 2) ² × n}
Light pressure is required for finger or pen pressure, and the range of the surface pressure P1 is usually preferably 0.005 to 0.02 MPa.
For example, assuming that 1000 particles / cm ² of conductive fine particles having a particle diameter of 5 μm are arranged and 0.005 to 0.02 MPa is applied to the surface pressure P1, the pressure P2 transmitted to the pressure-sensitive resin layer is 25 from the above equation. Here, the pressure threshold at which the pressure-sensitive resin layer 3 changes from an insulator to a conductor is 0.03 to 4.0 MPa, and the pressure transmitted to the pressure-sensitive resin layer as a result of the calculation is 0.03 to 4.0 MPa. P2 can sufficiently change into a conductor.
When the number n of the conductive fine particles per unit area increases, the transmittance deteriorates. When the number n decreases, the distance between the particles increases and the resolution of position detection deteriorates. Therefore, the range of 500 to 10000 particles / cm ² is preferable, and more preferably 800. ５5000 / cm ² , most preferably 1,000 to 2,000 / cm ² .
[0014]
Hereinafter, each component will be described in detail. The materials and thicknesses of the substrates 1 and 6 are not particularly limited, and inorganic glass such as barium borosilicate glass and soda glass, polyether sulfone (PES), polysulfone (PSF), and polycarbonate may be used according to the purpose of use. (PC), polyarylate (PAR), polyethylene terephthalate (PET), and other resin films. The transparent conductive films 2 and 5 are not particularly limited as long as they are transparent and conductive thin films, and conventional ITO (indium tin oxide), ATO (antimony tin oxide) and the like can be used.
[0015]
The pressure-sensitive resin layer of No. 3 is a film of a resin composition which is usually an insulator but is changed into a conductor by applying pressure. Specifically, the pressure-sensitive resin layer is preferably a polyphthalide of the formula (I), which will be described.
The polyphthalide represented by the formula (I) (hereinafter collectively referred to as polyphthalide) has a characteristic (pressure-sensitive conductivity) in which, when pressure is applied in the thickness direction, the electrical resistance in the thickness direction changes greatly and conductivity is exhibited. It is. A change in electrical resistance in the thickness direction of at least 6 orders of magnitude before and after pressurization at a relatively low pressure (usually, it shows insulation at atmospheric pressure and shows conductivity when pressed). It becomes possible.
Here, the change of the electric resistance by six digits or more means that the change of the electric resistance (or current) before and after pressurization becomes six digits or more when measured under a predetermined voltage application condition. More specifically, it means that the current value at a predetermined voltage changes from an order of 10 ⁻¹² A (insulator) to a conductive material of the order of 10 ⁻⁶ A or more.
Polyphthalide has a structure represented by Formula I.
Embedded image

[In the formula (I),
R represents a divalent aromatic hydrocarbon group or a divalent heterocyclic-containing aromatic group,
R ₁ is hydrogen, an alkyl group, a fluorinated alkyl group, an alkoxy group or a halogen, which may be plural (2 to 4);
X represents O or N—R ₃ (where R ₃ represents the following group);
Embedded image

Y represents SO ₂ or CO, and n represents the number of repeating units of the polymer. ]
Examples of R (a divalent aromatic hydrocarbon group or a divalent heterocyclic-containing aromatic group) in the formula (I) include the following groups.
Embedded image

Here, R ₂ is the same as R ₁ described above, and is _a hydrogen, an alkyl group, a fluorinated alkyl group, an alkoxy group, or a halogen (such as fluorine or chlorine). Good.
Examples of the alkyl group, the fluorinated alkyl group, and the alkyl group of the alkoxy group include an alkyl group having 1 to 20 carbon atoms, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a sec-butyl group. Group, tert-butyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl Group, octadecyl group, nonadecyl group, icosyl group, structural isomers thereof and the like. Further, the fluorinated alkyl is one in which all or a part of the alkyl group is substituted with fluorine. Examples of the halogen include fluorine, chlorine, bromine, iodine, and astatine.
Ar ₁ is the following groups.
Embedded image

Ar ₂ is the following groups.
Embedded image

[0016]
The polyphthalide may be a homopolymer, a copolymer, or a blend thereof.
[0017]
The refractive index of these polyphthalide resins is in the range of 1.6 to 1.8. For the purpose of improving the adhesion, a silane coupling agent and other polymers and monomers can be added. Further, a phthalide oligomer or an electron donating molecule may be added in order to improve the pressure-sensitive characteristics. Examples of the electron donating molecule include tetrathiafulvalene, bis (ethylenedithiolo) -tetrathiafulvalene, and aromatic diamine. The electron donating molecule is preferably blended in an amount of 1 to 10 parts by weight based on 100 parts by weight of the polyphthalide.
[0018]
Reference numeral 4 denotes a resin layer in which conductive fine particles are dispersed. The purpose of the conductive fine particles is to provide electrical continuity between the transparent conductive film and the pressure-sensitive resin layer and to transmit pressure applied by a finger or a pen to the pressure-sensitive resin layer. In order to obtain a uniform pressure response over the entire panel surface, a single particle size and a particle size distribution having an average particle size of ± 0.3 μm, preferably ± 0.2 μm, more preferably ± 0.1 μm are preferable. The particles are preferably uniform spherical fine particles, and the thickness of the resin layer in which the conductive fine particles are dispersed is preferably approximately equal to the particle size of the conductive fine particles (± 0.3 mm). The particle size of the conductive fine particles is selected from the range of 1 to 10 μm. From the viewpoint of improving the transmittance, the resin layer is preferably as thin as possible, and the particle size of the fine particles is in the range of 3 to 7 μm. Is most preferred. The conductive fine particles need only have a conductive layer on at least the surface.For example, in addition to metal fine particles of nickel, gold, silver, copper, etc., fine particles of insulating inorganic fine particles or resin fine particles subjected to metal plating are used. it can. The resin used for the resin layer in which the conductive fine particles are dispersed is not particularly limited as long as it is transparent and has elasticity, but is close to the refractive index of the transparent electrode for the purpose of improving transmittance. The value is better. For example, high molecular resins such as butyl rubber, urethane rubber, silicone rubber, fluorine rubber, polyvinyl alcohol, acrylic resin, and urethane resin can be mentioned, and the refractive index of these resins is preferably in the range of 1.5 to 1.7.
[0019]
As a manufacturing method for obtaining the input panel of the present invention, a pressure-sensitive resin layer and a resin layer in which fine particles having conductivity are dispersed are sequentially coated on a substrate with a transparent conductive film by a spin coating method, dried, and finally transparent. In addition to being obtained by attaching a substrate with a conductive film, the cover film of the film-like substrate of the present invention to be described later is peeled off (when a cover film is provided), and is attached to a substrate having a transparent conductive film. The method is the simplest and cheapest method. It is desirable that the cover film be chemically and thermally stable and easily peeled off from the pressure-sensitive conductive fine particle dispersed resin layer. Specifically, a thin sheet made of polyethylene, polypropylene, polyethylene terephthalate, polyvinyl alcohol or the like and having high surface smoothness is preferable. The surface may be subjected to a release treatment to impart releasability.
[0020]
As a method of obtaining a film-shaped substrate, a resin layer in which conductive fine particles are dispersed by a coating machine such as a die coater, a comma coater, and a gravure coater, and a pressure-sensitive resin layer are sequentially coated on a roll-shaped transparent conductive film. It is the simplest and cheapest method to apply a cover film and wind it up as necessary, that is, roll-to-roll, and it is easy to deal with a large area.
[0021]
In order to obtain a film-like base material, it is possible to obtain a film-like base material similarly by changing the order of the pressure-sensitive resin layer and the resin layer in which conductive fine particles are dispersed in the above-mentioned method.
[0022]
In the conventional input panel, there is a gap layer (refractive index: 1.0) between the upper and lower transparent conductive films (refractive index: 1.9), and the refractive index difference is as large as about 0.9. This was a major factor in reducing the transmittance of the entire panel. However, in the input panel of the present invention, a pressure-sensitive resin layer (refractive index: 1.6 to 1.8) and a resin layer in which conductive fine particles are dispersed between upper and lower transparent conductive films (refractive index: 1.9). Since (1.5 to 1.7) are arranged, the transmittance of the entire panel is greatly improved as compared with the conventional panel. Also, unlike the conventional input panel, in which the upper electrode is bent to contact the upper and lower electrodes, the amount of deflection of the upper electrode is very small, so there is almost no deterioration due to electrode peeling, etc., and product reliability related to repeated use Is greatly improved. Furthermore, since it is spacerless, uniform responsiveness and resolution can be obtained over the entire surface.
[0023]
【Example】
(Example 1)
Poly (4,4'-diphenylenemethylphthalide) represented by the following formula is converted to cyclohexanone.

It was dissolved in a solvent to prepare a 10 wt% pressure-sensitive resin coating solution. Also, an acrylic rubber is dissolved in a methyl ethyl ketone solvent to prepare a 5 wt% acrylic rubber solution. Further, spherical conductive fine particles having an average particle diameter of 5 μm (± 0.1 μm) (polystyrene fine particles plated with Ni + Au, product name Micropearl (trade name, manufactured by Sekisui Fine Chemical Co., Ltd.) was dispersed at 0.05 wt% (based on the whole) to obtain a conductive fine particle dispersed resin coating liquid.
The above pressure-sensitive resin coating solution was applied onto a glass substrate (thickness 0.7 mm) provided with an ITO transparent conductive film (surface resistance 200 Ω / □) by spin coating, and dried at 100 ° C. The number of revolutions was adjusted so that the thickness of this coating film was about 1 μm. Next, an acrylic rubber coating solution in which the spherical conductive fine particles were dispersed was applied by a spin coating method, and dried at 100 ° C. At this time, the number of rotations was adjusted so that the thickness of the coating film was about 5 μm. Finally, a PET film (125 μm in thickness) with an ITO transparent conductive film was attached by a lamination method so that the film surface was on the inside. Through the above operations, an input panel was obtained. A voltage of 5 V was applied between the PET side electrode and the glass substrate side electrode of this input panel. Under normal pressure, it showed an insulation property of resistance 10 ¹⁴ Ω · cm, but when a pressure of 0.015 MPa was applied to the surface of the input panel, it showed conductivity of resistance 10 ³ Ω · cm.
[0024]
(Example 2)
An acrylic rubber coating liquid in which the spherical fine particles described in Example 1 were dispersed was applied by a comma coater to the film surface side of the ITO transparent conductive film-attached PET film (125 μm in thickness) wound into a roll. Next, the pressure-sensitive resin coating solution described in Example 1 was applied using a die coater, and was wound while a cover film made of PE (polyethylene, 23 μm in thickness) was attached to the coating surface. At the time of coating, both ends of the ITO transparent electrode film were provided with uncoated portions as electrode extraction positions. A film-like substrate was obtained by the above operation. Next, this film substrate was affixed by a lamination method onto a glass substrate with an ITO transparent conductive film (thickness: 0.7 mm) while peeling off the cover film.
Through the above operations, an input panel was obtained. A voltage of 5 V was applied between the PET side electrode and the glass substrate side electrode of this input panel. Under normal pressure, it showed an insulation property of resistance 10 ¹⁴ Ω · cm, but when a pressure of 0.015 MPa was applied to the surface of the input panel, it showed conductivity of resistance 10 ³ Ω · cm.
[0025]
(Example 3)
A poly (4,4'-diphenylenephthalide) represented by the following formula is converted to a cyclohexanone solvent:

To prepare a 10 wt% pressure-sensitive resin coating solution.
The pressure-sensitive conductive resin and the acrylic resin in which the spherical fine particles described in Example 1 were dispersed were sequentially coated on the film surface side of the PET film with the ITO transparent conductive film (thickness: 125 μm) wound in a roll by a die coater. (Polyethylene, 23 μm thick) was wound while being attached to the coated surface. At the time of coating, both ends of the ITO transparent electrode film were provided with uncoated portions as electrode extraction positions. A film-like substrate was obtained by the above operation. Next, this film-shaped substrate was attached to a glass substrate with an ITO transparent conductive film by a laminating method while peeling off the cover film.
Through the above operations, an input panel was obtained. A voltage of 5 V was applied between the PET side electrode and the glass substrate side electrode of this input panel. Under normal pressure, it showed an insulation property of resistance 10 ¹⁴ Ω · cm, but when a pressure of 0.015 MPa was applied to the surface of the input panel, it showed conductivity of resistance 10 ³ Ω · cm.
[0026]
(Example 4)
Poly (4,4'-diphenylene sulfophthalide) represented by the following formula is converted to cyclohexanone.

It was dissolved in a solvent to prepare a 10 wt% pressure-sensitive resin coating solution.
The pressure-sensitive conductive resin and the acrylic resin in which the spherical fine particles described in Example 1 were dispersed were sequentially coated on the film surface side of the PET film with the ITO transparent conductive film (thickness: 125 μm) wound in a roll by a die coater. (Polyethylene, 23 μm thick) was wound while being attached to the coated surface. At the time of coating, both ends of the ITO transparent electrode film were provided with uncoated portions as electrode extraction positions. A film-like substrate was obtained by the above operation. Next, this film substrate was affixed by a lamination method onto a glass substrate with an ITO transparent conductive film (thickness: 0.7 mm) while peeling off the cover film.
Through the above operations, an input panel was obtained. A voltage of 5 V was applied between the PET side electrode and the glass substrate side electrode of this input panel. Under normal pressure shows the insulation resistance ^{10 1 4 Ω} · cm, but showed a conductivity of the resistance 10 ³ Ω · cm applying a pressure of 0.015MPa on the surface of the input panel.
[0027]
【The invention's effect】
As described above, according to the input panel of the present invention, it is possible to provide a spacer-less input panel that has higher transmittance of the entire panel and higher product reliability than conventional input panels.
In addition, by using the film-shaped substrate of the present invention, the above-mentioned input panel can be manufactured simply and at low cost.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an input panel of the present invention.
FIG. 2 is a diagram showing how pressure is transmitted to the input panel of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 substrate 2 transparent conductive film 3 pressure-sensitive resin layer 4 resin layer in which conductive fine particles are dispersed 5 transparent conductive film 6 substrate

Claims (9)

An input panel in which a transparent conductive film, a pressure-sensitive resin layer, and a resin layer in which conductive fine particles are dispersed are sequentially laminated on a substrate, and a substrate having a transparent conductive film is laminated thereon such that the transparent conductive film is on the inside. . The input panel according to claim 1, wherein the pressure-sensitive resin layer is a resin layer containing polyphthalide represented by Formula I as a main component.

[In the formula (I),
R represents a divalent aromatic hydrocarbon group or a divalent heterocyclic-containing aromatic group,
R ₁ is hydrogen, an alkyl group, a fluorinated alkyl group, an alkoxy group or a halogen, which may be plural (2 to 4);
X represents O or N—R ₃ (where R ₃ represents the following group);

Y represents SO ₂ or CO, and n represents the number of repeating units of the polymer. ] In the resin layer in which the conductive fine particles are dispersed, the conductive fine particles are spherical, have an average particle size of 1 to 10 μm, and the particle size distribution is in a range of the average particle size ± 0.3 μm. The input panel according to claim 1 or 2. 4. The input panel according to claim 1, wherein a thickness of the resin layer in which the conductive fine particles are dispersed is made equal to a particle diameter of the fine particles. A film-shaped substrate in which a transparent conductive film, a resin layer in which fine particles having conductivity are dispersed, and a pressure-sensitive resin layer are sequentially laminated on a film. A film-shaped substrate in which a transparent conductive film, a pressure-sensitive resin layer, and a resin layer in which conductive fine particles are dispersed are sequentially laminated on a film. A film-like substrate obtained by further attaching a cover film to the film-like substrate according to claim 5. The film-shaped substrate according to any one of claims 5 to 7, wherein the pressure-sensitive resin layer is a resin layer containing a polyphthalide represented by Formula I as a main component.

[In the formula (I),
R represents a divalent aromatic hydrocarbon group or a divalent heterocyclic-containing aromatic group,
R ₁ is hydrogen, an alkyl group, a fluorinated alkyl group, an alkoxy group or a halogen, which may be plural (2 to 4);
X represents O or N—R ₃ (where R ₃ represents the following group);

Y represents SO ₂ or CO, and n represents the number of repeating units of the polymer. ] When the cover film of the film-like substrate according to any one of claims 5 to 8 is present, the cover film is peeled off and attached on a substrate having a transparent conductive film. A method for manufacturing an input panel for obtaining the input panel according to any one of the above.

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