JP4270806B2 - Method for producing antireflection article by sol-gel method - Google Patents

Description

【００３３】
となる。その結果、有効屈折率（ｎ_ef）の分布はｚのみの関数ｎ_ef（ｚ）となる（図４参照）。
【００３４】
よって、もしも、微細凹凸２に於ける微細凹凸層３の凸部の断面積が、凹部に向かって連続的に増大する様な形状であれば（ＸＹ平面内に於ける）微細凹凸層部分と空気部分との面積比がＺ軸方向に向かって連続的に変化する為、有効屈折率ｎ_ef（ｚ）はｚに付いての連続関数になる。
【００３５】
一方、一般に屈折率ｎ₀の媒質から、屈折率ｎ₁の媒質に光が入射する場合を考える。今、簡単の為に、入射角θ＝０°（垂直入射）を考える。但し、入射角は入射面の法線に対する角度とする。
この場合、媒質界面での反射率Ｒは、偏光、及び入射角には依存せず、下記の〔式２〕となる。
【００３６】
【数２】

【００３７】
従って、（有効）屈折率のＺ方向への変化が連続関数であるということは、Ｚ方向（光の進行方向）に微小距離Δｚ隔てた２点、Ｚ＝ｚに於ける屈折率ｎ_ef（ｚ）をｎ₀、Ｚ＝ｚ＋Δｚに於ける屈折率ｎ_ef（ｚ＋Δｚ）をｎ₁、としたときに、
【００３８】
Δｚ→０ ならば、 ｎ₁→ｎ₀
【００３９】
となり（連続関数の定義より）、よって、〔式２〕より、
【００４０】
Ｒ→０
【００４１】
となる。
【００４２】
なお、ここで、より厳密に言うと、物体中での光の波長は、真空中の波長をλ、物体の屈折率をｎとしたときに、λ／ｎとなり、λよりは一般に或る程度小となる。但し、物体が空気の場合の屈折率はｎ≒１の為、λ／ｎ≒λと考えて良い。但し、微細凹凸層に使われる材料は、通常１．５前後の屈折率である為、屈折率ｎ_bの基材中の波長（λ／ｎ_b）は、０．７λ程度となる。この点を考慮すると、微細凹凸２の部分に於いて、空気の側の部分（微細凹凸２の凹部）について見れば、
【００４３】
Ｐ_MAX≦λ_MIN
【００４４】
の条件を満たすとき、屈折率平均化による反射率低減効果が期待出来る。但し、
【００４５】
λ_MIN／ｎ_b≦Ｐ_MAX≦λ_MIN
【００４６】
である場合は、微細凹凸層の部分（微細凹凸２の凸部）の寄与について見れば、屈折率平均化による反射率低減効果は、少なくとも完全には期待出来ないことになる。
しかし、それでも、空気部分に於ける寄与の為、全体としては反射防止効果を有する。
そして、
【００４７】
Ｐ_MAX≦λ_MIN／ｎ_b
【００４８】
の条件までも満たす場合は、空気部分、微細凹凸層部分とも、周期Ｐ_MAXが、最短波長よりも小さいと言う条件が完全に満たされる為、屈折率平均化による反射防止効果は、より完全となる。
具体的には、λ_MINを可視光波長帯域の下限３８０ｎｍ、ｎ_bを仮に１．５とすれば、λ_MIN／ｎ_bは２５０ｎｍ、つまりＰ_MAXは２５０ｎｍ以下とすれば良い。
【００４９】
次に、微細凹凸２の形状は、微細凹凸をその凹凸方向と直交する面（ＸＹ平面）で切断したと仮定したときの断面（水平断面）内に於ける微細凹凸層の材料部分の断面積占有率が、該微細凹凸の最凸部（頂上）から最凹部（谷底）に行くに従って連続的に漸次増加して行く形状とする。この為には、微細凹凸の山は少なくともその一部の側面が斜めの斜面を有するものとすれば良いが、下記する図５（Ｃ）の様に斜面と共に垂直側面がある形状の微細凹凸でも良い。特に、好ましくは、最凸部に於いて完全に０に収束し、且つ最凹部に於いて完全に１に収束する形状とする。具体的には例えば、図５（Ｂ）、図５（Ｃ）の如き形状が挙げられる。但し、図５（Ｄ）、或いは図５（Ｅ）の如く、最凸部に於いては、ほぼ０に漸近した形状、或いは、最凹部に於いてほぼ１に漸近する様な形状であれば、或る程度の効果は得られる。微細凹凸の形状は、この様な条件を満たせば、どんな形状でも良い。
【００５０】
例えば、個々の微細凹凸２の垂直断面形状は、図５（Ａ）の如き正弦波等の曲線のみによる波状の形状〔図２も参照〕、図５（Ｂ）及び図５（Ｃ）の如き三角形等の直線のみによる形状、或いは、図５（Ｄ）の如き三角形の最凸部が平坦面を成す形状である台形の形状、図５（Ｅ）の如き隣接する三角形間の最凹部が平坦面を成す形状等である。但し、図５（Ｄ）や図５（Ｅ）の如く、最凸部或いは最凹部に平坦面を有する形状では、最凸部或いは最凹部の平坦面の部分で、その平坦面の占める面積割合が大きい程、有効屈折率の変化がより大きく不連続となる。その点で性能的には劣るものとなる。しかし、この場合でも、微細凹凸の最凸部から最凹部に行くに従って有効屈折率を連続的に変化させることは出来る。従って、反射防止性能の点では、最凸部或いは最凹部の平坦面の面積割合は少ない程好ましい。
【００５１】
また、有効屈折率ｎ_ef（ｚ）を空気中から微細凹凸層中に向かうＺ方向の関数として、ｎ_aからｎ_bに連続的に変化する様にする為には、微細凹凸の最凸部に於いて、微細凹凸層の断面積占有率が０に収束する図５（Ｂ）或いは図５（Ｃ）の如き形状（すなわち、尖った形状）で且つ最凹部に於いて該断面積占有率が連続的に１に収束する形状が最も好ましい。
【００５２】
次に、個々の微細凹凸の水平断面形状は、円形（例えば図２）、楕円形、三角形、四角形、長方形、六角形、其の他多角形等任意である。なお、水平断面形状は、微細凹凸の最凸部から最凹部の全てにわたって同じである必要は無い。従って、微細凹凸の立体形状は、例えば、水平断面形状が円形で垂直断面形状が正三角形の場合の微細凹凸の立体形状は円錐に、水平断面形状が円形で垂直断面形状が三角形の場合の微細凹凸の立体形状は斜円錐に、水平断面形状が三角形で垂直断面形状が正三角形の場合の微細凹凸の立体形状は三角錐に、水平断面形状が四角形で垂直断面形状が三角形の場合の微細凹凸の立体形状は四角錐になる。
【００５３】
また、微細凹凸の、水平面内に於ける配置は、図２で例示した如く二次元的配置の他に、図６（Ａ）の斜視図で例示の直線溝状の微細凹凸２の如く、一次元的配置でも良く、どちらも効果は得られる。但し、一次元的配置の場合は、光の波の振幅方向との関係で、反射防止効果が得られる方向と得られない方向とが出る、異方性が発生する。従って、図２の斜視図や図６（Ｂ）及び（Ｃ）の平面図で例示の様な二次元的配置の方が、方向性が全く無い点で好ましい。
【００５４】
なお、個々の微細凹凸の立体形状は全て同一でも良いが、全て同一で無くても良い。また、個々の微細凹凸２を二次元配置する場合に、周期は、個々の微細凹凸に於いて全て同一でも良いが、全て同一で無くても良い。
【００５５】
また、微細凹凸の高さＨは、希望する反射率の低減効果と微細凹凸層表面に入射する可視光帯域の最大波長に応じて決定する。例えば、特開昭５０−７００４０号公報（特にその第３図）記載の反射率、微細凹凸の高さ、及び光波長との関係を基に設計する場合、例えば、可視光帯域での反射率を、２％（未処理の硝子の場合の半分）以下に低減させることを目標とするならば、その最小高さＨ_MINが０．２λ_MAX以上、すなわち、
【００５６】
Ｈ_MIN≧０．２λ_MAX
【００５７】
また、可視光帯域での反射率を０．５％以下にまで低減させることを目標とするならば、
【００５８】
Ｈ_MIN≧０．４λ_MAX
【００５９】
とするのが好ましい。なお、ここで、λ_MAXは、可視光波長帯域の真空中に於ける最大波長である。微細凹凸の高さＨは、ゼロから高くなるに従って反射率が低下して行くが、上記不等号条件を満足させる高さまで達すると、有為な効果が得られる様になる。具体的には、例えば、発光スペクトルの最大波長が、λ_MAX＝６４０ｎｍの蛍光灯を用いたとすれば、Ｈ_MIN≧０．２λ_MAX＝１２８ｎｍとかなる。すなわち、Ｈ_MINは１２８ｎｍ以上とすれば良い。また、スペクトルの最大波長がλ_MAX＝７８０ｎｍの太陽光線を考えるならば、Ｈ_MIN≧０．２λ_MAX＝１５６ｎｍ、すなわち、Ｈ_MINは１５６ｎｍ以上とすれば良い。また、最小高さＨ_MINと周期Ｐ_MAXとの関係では、最小高さＨ_MIN／周期Ｐ_MAXの比を、１／２〜４／１程度とする。
【００６０】
ここで、微細凹凸の具体的形状及び大きさを例示すれば、形状は垂直断面が正弦波状で水平断面が円形の円錐状の形状のものを多数、二次元的に規則的配置した集合体であり、周期期Ｐ_MAXが５０〜２５０ｎｍ、最小高さＨ_MINを前記周期Ｐ_MAXの１．５倍としたもの等がある。
【００６１】
〔賦形型の作製〕
ゾルゲル法による塗布膜を賦形する為に使用する賦形型として、微細凹凸形状を最初に造形した原型を用いても良いが、生産性等の点で、より好ましくは、該原型から１回、或いは２回以上の型取・反転による複製工程を経て作製した複製型を用いるのが良い。つまり、最初に一旦、原型（これを原版、或いはマザー版とも呼ぶ）を作製した後、この原型から複製型を作製する複製操作を１回又は２回以上の多数回行い、その結果、得られた複製型（これを本版、或いはマスター版とも呼ぶ）をゾルゲル法による塗布膜に対して使用する賦形型として採用するのである。この様な方法とすることで、工業的生産性、コスト等に優れた方法となる。
【００６２】
賦形型の元となる原型としては、必要な微細凹凸が形成されているのものであれば、その作製方法には基本的には特に限定は無く、生産性、コスト等を考慮して適宜なものを使用すれば良い。原型の作製は、微細凹凸２を賦形する為の凹凸形状を最初に造形する工程であり、半導体分野等に於ける微細加工技術、すなわち、光（含む電子ビーム）をパターン形成に利用する所謂露光法を利用できる。但し、半導体の場合は、凹凸形状はその側面が通常垂直面で良く、本発明の如く斜面にする必要は特に無いため、本発明では、斜面が形成できる様にして微細加工する。
【００６３】
上記の如き微細加工技術としては、電子線描画法を利用できる。この方法では、先ず、ガラス基板の上にレジスト層を形成した後、電子線描画法により該レジスト層を露光し現像してパターニングしてレジストパターン層とする。この後、腐蝕マスクに該レジストパターン層を利用してガラス基板をドライエッチング法等により腐蝕することで、ガラス基板に微細凹凸形状が形成される。この際、エッチング時にサイドエッチングさせて、斜面を形成する。また、ガラス基板腐蝕時の腐蝕マスクとしてはレジストパターン層自体を直接用いても良いが、斜面を有する深い凹凸形状を形成するには、好ましくは、ガラス基板上にクロム等による金属層を設けた後、レジスト膜を形成してレジストパターン層を得、前記金属層をこのレジストパターン層を利用して金属パターン層としてたものを、腐蝕マスクとして用いるのが良い。
【００６４】
また、レジスト膜へのパターン形成に際しては、電子線描画法の他に、レーザー描画法も利用できる。レーザ描画法では、ホログラム、回折格子等の作製等に利用されているレーザ干渉法が利用できる。回折格子の場合は、一次元的配置であるが、角度を変えて多重露光すれば、二次元配置も可能となる。但し、レーザ干渉法では、得られる微細凹凸は、通常規則的配置となるが、電子線描画法では、予め所定の描画パターン情報を記憶装置にデジタルデータとして記憶しておき、該描画パターン情報により、走査する電子線のＯＮ、ＯＦＦ、乃至は強弱を変調する。その為、規則配置の他にも、不規則配置も可能である。また、レーザー描画法及び電子線描画法には各々長所、短所が有る為、設計諸元、目的、生産性等を考慮の上、適宜な手法及び条件を選択する。
【００６５】
次に、上記原型から賦形型として使用する複製型を作製する方法としては、公知の方法、例えば、原型にニッケル等の金属めっきを行って、めっき層を剥がせば金属製の複製型を作製できる（電鋳法）。或いは、この複製型にもう一度めっきして、再度複製した型を賦形型とするなど、２以上の多数回の複製操作を経て賦形型を作製しても良い。なお、ゾルゲル法で形成した塗布膜に対する賦形型の形態としては、板状、シート状、ブロック状等があり得、反射防止物品の形状、用途等に応じて適宜選択すれば良い。なお、賦形型は、上記ニッケルの如き金属製でも良いが、シリコーン樹脂等の樹脂製のものを使用しても良い。例えば、樹脂からなるシート状で連続帯状も可能な賦形型である。
【００６６】
〔ゾルゲル法〕
ところで、ゾルゲル法は、アルコキシシラン等の有機金属化合物を金属酸化物の前駆体として含むゾルゲル液を基材上に塗布した塗布膜から、金属酸化物からなる無機質系塗膜を形成する方法として知られている。また、最近では、有機無機複合膜を形成する方法としても知られている。これらのゾルゲル法にて、基材が樹脂シート等の場合には、塗布膜を高温で熱処理して有機質成分を燃焼・消失させる焼成工程は含めないが、基材がガラス等の無機質材料の場合には、基材が高熱に耐え得る為に、更に塗布膜を焼成して完全な無機質膜とすることもできる。
【００６７】
この様なゾルゲル法による塗布膜に対して、更にその表面に凹凸形状を形成方法としては、例えば、特開昭６２−２２５２７３号公報、特開平６−９４９０７号公報、或いは、「ゾル−ゲル法によるマイクロパターニング」（セラミックス，ｖｏｌ３７，Ｎｏ．３，ｐ１６１−１６４，２００２）等として提案されている。これらの文献によれば、金属アルコキシドを含むゾルゲル液の溶液を塗布して形成した可塑性状態の塗布膜に対して、賦形型を押圧してその表面に、回折格子、光ディスク基板の溝等の微細な凹凸形状を賦形する方法が提案されている。
【００６８】
ゾルゲル液としては、樹脂シートやガラス等の各種基材に対するゾルゲル液として適用されている公知のものを使用できるが、本発明では少なくとも賦形型を押圧するときは可塑性を呈する事が好ましい。もしも、塗布膜の塗布から硬化までの間で可塑性を呈する時間が少なく、賦形の作業性が悪い様ならば、可塑性を増大する為に、例えば、溶液の粘度を上昇させる樹脂や低分子化合物等を適宜添加するのも好ましい。
【００６９】
ゾルゲル液として使用される有機金属化合物としては、重縮合反応や架橋反応等によって、その粘度が上昇する様な化合物を使用することができる。有機金属化合物としては、例えば、一般式Ｒ_nＭ（ＯＲ’）_mで表される金属アルコキシド化合物や、その加水分解物等が挙げられる。なお、上記式中、Ｍは、Ｓｉ、Ｔｉ、Ｚｒ、Ａｌ、Ｃａ、Ｎａ、Ｐｂ、Ｂ、Ｓｎ、Ｇｅ等の金属を表し、Ｒ及びＲ’はメチル基、エチル基、プロピル基、ブチル基等のアルキル基を表し、ｎ及びｍは、ｎ＋ｍが金属Ｍの原子価となる整数を表す。従って、例えば金属Ｍがケイ素Ｓｉの場合には、上記一般式は、Ｒ_nＳｉ（ＯＲ’）_n-4となる。
【００７０】
更に、上記の如き金属アルコキシ化合物の具体例を挙げれば、Ｓｉ（ＯＣＨ₃）₄、Ｓｉ（ＯＣ₂Ｈ₅）₄等のケイ素系アルコキシド化合物、Ｔｉ（ＯＣ₃Ｈ₇）₄、Ｔｉ（ＯＣ₄Ｈ₉）₄等のチタン系アルコキシド化合物、Ｚｒ（ＯＣ₃Ｈ₇）₄、Ｚｒ（ＯＣ₄Ｈ₉）₄等のジルコニウム系アルコキシド化合物、Ａｌ（ＯＣ₃Ｈ₇）₄、Ａｌ（ＯＣ₄Ｈ₉）₄等のアルミニウム系アルコキシド化合物、ＮａＯＣ₂Ｈ₅等のナトリウム系アルコキシド化合物等が挙げられる。
更に、ケイ素系アルコキシド化合物の具体例を挙げれば、メチルトリエトキシシラン〔（ＣＨ₃）Ｓｉ（ＯＣ₂Ｈ₅）₃〕、メチルトリプロポキシシラン〔（ＣＨ₃）Ｓｉ（ＯＣ₃Ｈ₇）₃〕、ジメチルジエトキシシラン〔（ＣＨ₃）₂Ｓｉ（ＯＣ₂Ｈ₅）₂〕等が挙げられる。
【００７１】
また、有機金属化合物としては、一般式Ｘ_nＭ（ＯＲ’）_mで表される金属アルコキシド化合物〔但し、上記式中Ｘは、アミノ基、カルボキシル基、グリシジル基、アクリロイルオキシ基、メタクリロイルオキシ基等の反応性官能基〕、例えば金属がケイ素の場合では所謂シランカップリング剤と称される化合物等も使用することができる。
【００７２】
また、賦形時の可塑性の向上の為に添加する樹脂や低分子化合物としては、例えば、アクリル系樹脂、ポリビニルアルコール等の熱可塑性樹脂、ポリエチレングリコール、ポリプロピレングリコール、ポリテトラエチレングリコール等のポリエーテル化合物等の低分子有機化合物を使用することができる。
また、ゾルゲル液には、水、或いは、メタノール、エタノール等のアルコール、メチルエチルケトン、メチルイソブチルケトン等のケトン、酢酸エチル、酢酸ブチル等のエステル等の溶剤を適宜使用する。また、ゾルゲル液には、塩酸等の酸やアルカリを、有機金属化合物やその加水分解物等の加水分解反応を促進する触媒として適宜使用する。
【００７３】
〔賦形型による賦形〕
そして、ゾルゲル液を塗布して形成した塗布膜に対して、前述の如き賦形型を押圧し離型すれば、塗布膜表面には所望の微細凹凸が賦形され、微細凹凸層が得られる。また、賦形時は塗布膜は可塑性状態とするが、賦形後に更に反応を進めて塗膜を完全に固化させて微細凹凸層とする。なお、賦形時は適宜加熱しても良い。
【００７４】
〔焼成〕
賦形型を離型した後、基材がガラス等の無機質基材で焼成温度に耐え得る材料のものであれば、更に賦形後に得られた微細凹凸層を焼成して、有機質成分が残存する場合はそれを焼いて無機質層としても良い。焼成することにより、微細凹凸を表面に有する微細凹凸層は、耐熱性、耐候性、硬度、耐洗浄性等がより優れたものとなる。従って、例えば、微細凹凸の上に更にＩＴＯ膜等の透明導電膜を物理的手法により形成する場合等の耐熱性が要求される後処理も適用できる反射防止物品が得られる。なお、焼成温度は、通常２００℃以上、例えば４５０℃等である。また、焼成工程を経る事によって、賦形型で賦形し易い様に樹脂や低分子有機化合物をゾルゲル液に添加してある場合でも、これらの有機質成分を燃焼させて、有機質成分が残らない無機質層として微細凹凸層を形成することができる。従って、これら有機質成分の残存による、耐熱性、耐候性、硬度、耐洗浄性等の性能低下を防げる。
【００７５】
なお、基材がガラス等の無機質基材の場合であっても、上記の如き耐熱性、耐候性、硬度、耐洗浄性等の性能が過剰性能となるのであれば、焼成工程は省略することもできる。焼成工程を省略すれば、それにかかる処理時間が短縮されるので、生産性が向上する。また、基材が有機質材料で樹脂シート等の連続帯状の基材の場合では、焼成工程は実施できないが、連続処理も可能で生産性が優れた製造方法となる。
【００７６】
〔基材〕
基材１としては、特に限定されないが。ガラス（含むセラミックス）等の無機質材料、熱可塑性樹脂、熱硬化性樹脂等の合成樹脂を用いることができる。なお、塗布膜を焼成する場合は、焼成時の耐熱性の点で基材としては無機質材料が好ましい。基材の材料には、反射防止物品の用途に応じた材料を使用すれば良い。また、基材には、通常、透明なものを使用する。
【００７７】
なお、無機質材料の基材としては、ソーダガラス、石英ガラス等のガラス、セラミックス等が挙げられる。
また、有機質材料の基材としては、熱可塑性樹脂が代表的であり、例えば、ポリ（メタ）アクリル酸メチル、ポリ（メタ）アクリル酸エチル、（メタ）アクリル酸メチル−（メタ）アクリル酸ブチル共重合体等のアクリル樹脂〔但し、（メタ）アクリルとはアクリル、或いはメタクリルを意味する。〕、ポリカーボネート樹脂、ポリプロピレン、ポリメチルペンテン、環状オレフィン系高分子（代表的にはノルボルネン系樹脂等があるが、例えば、日本ゼオン株式会社製の製品名「ゼオノア」、ＪＳＲ株式会社製の「アートン」等がある）等のポリオレフィン系樹脂、ポリエチレンテレフタレート、ポリエチレンナフタレート等の熱可塑性ポリエステル樹脂、ポリアミド樹脂、ポリスチレン、アクリロニトリル−スチレン共重合体、ポリエーテルスルフォン、ポリスルフォン、セルロース系樹脂、塩化ビニル樹脂、ポリエーテルエーテルケトン、ポリウレタン等が挙げられる。
【００７８】
〔反射防止物品の用途〕
なお、本発明による反射防止物品としては、形状は、三次元形状、板、シート等任意であり、用途も特に限定れるものでは無い。但し、その反射防止表面の微細凹凸は、極めて微細であるが故に、汚れや傷に対して注意するに越したことは無いので、微細凹凸は好ましくは外面には露出させず、内面に設けられる用途、或いは、装置内部に設けられる用途等が好適である。なお、本発明が適用し得る用途は、これから例示される用途に限定されるものではない。
【００７９】
例えば、携帯電話、デシタルカメラ等の各種機器に於ける情報表示部の窓材である。これら表示部では、ＬＣＤ等の表示パネルの前面に、板や成形品等となった樹脂製或いはガラス製の窓材が配置される。窓材としての反射防止物品は、外側は露出する為に傷や汚れへの耐性の点で本発明特有の微細凹凸は設けず、内側の裏面の側に該微細凹凸を設けたものとするのが好ましい。なお、情報表示部は、ＬＣＤ等の表示パネル以外に、時計に代表される機械式アナログメータ等の様な機械的手段で表示するものでもよく、これらの窓材でも良い。
なお、窓材は、平板状もあるが、組み付けやデザイン上の観点から周囲に突起等有するものもある。
【００８０】
なお、上記の様な窓付き情報表示部を有する機器としては、携帯電話、時計の外にも、パーソナルコンピュータ、電子手帳等のＰＤＡ乃至は携帯情報端末、電卓、或いは、ＣＤプレーヤー、ＤＶＤプレーヤ、ＭＤプレーヤ、半導体メモリ方式音楽プレーヤ等の各種携帯型音楽プレーヤ、或いは、ビデオテープレコーダ、ＩＣレコーダ、ビデオカメラ、デシタルカメラ、ラベルプリンタ等の電子機器、或いは、電気炊飯器、電子ポット、洗濯機等の電気製品等がある。
【００８１】
また、板状やシート状の反射防止物品に於いては、透明タッチパネル等に使用する透明板等の透明基材が挙げられる。透明タッチパネルは、表示部に入力機能を付加するものであるが、該製品組立上、ＬＣＤ、ＣＲＴ等の表示パネルと別部品として組み付けるので、表示パネルと透明タッチパネル間に空隙が残り、光反射が生じる。そこで、透明タッチパネルの裏面側を成す透明基材を、その裏面を本発明特有の微細凹凸を設けた反射防止物品とすれば、光反射が防げる。
【００８２】
なお、透明タッチパネルは、例えば、電子手帳等のＰＤＡ乃至は携帯情報端末（機器）、或いは、カーナビゲーションシステム、ＰＯＳ（販売時点情報管理）端末、携帯型オーダー入力端末、ＡＴＭ（現金自動預金支払兼用機）、ファクシミリ、固定電話端末、携帯電話機、デシタルカメラ、ビデオカメラ、パソコン、パソコン用ディスプレイ、テレビジョン受像機、テレビ用モニターディスプレイ、券売機、計測機器、電卓、電子楽器等の電子機器、複写機、ＥＣＲ（金銭登録機）等の事務器、或いは、洗濯機、電子レンジ等の電気製品に使用される。
また、本発明の反射防止物品は、各種光学部品としての用途も挙げられる。例えば、写真機のレンズ、写真機のファインダの窓材、眼鏡のレンズ、オーバーヘッドプロジェクタのフレネルレンズ、レーザ装置の出力取出窓、光センサの光入力窓、望遠鏡のレンズ等が挙げられる。
【００８３】
【実施例】
以下、実施例により本発明を更に詳述する。
【００８４】
〔実施例１〕
次の様にして、賦形型、ゾルゲル液を用意して、図１（Ｅ）の如き表面に微細凹凸２を有する微細凹凸層３が、基材１上に積層された構成の透明な反射防止物品１０を作製した。
【００８５】
（１）賦形型の作製：石英ガラス基板の片面に金属クロム膜を形成した後、その上にポジ型レジストをスピンコートしてレジスト膜を形成した。次いで、このレジス膜に、縦横周期３００ｎｍのメッシュ状描画データを電子線描画装置にて描画後、現像液で現像し、前記メッシュ開口領域が開口したレジストパターン層を形成した。次いで、該レジストパターン層の開口部から露出している金属クロム膜を塩素系ガスでドライエッチングした。そして、レジストパターン層と金属クロム膜を耐エッチング層として、ガラス基板をフッ素系ガスでドライエッチングして、所望の微細凹凸形状が造形された原型（マザー版）を作製した。次に、この原型から、電気めっき法によって、厚さ８０μｍのニッケルめっきプレートからなる複製型（ニッケルスタンパ）を賦形型として作製した。
【００８６】
（２）ゾルゲル液の作製：ゾルゲル液としては、高分子量ＳｉＯ₂ゾル溶液と、低分子量ＳｉＯ₂ゾル溶液とを各々調整し、これらを混合して作製した。
【００８７】
（２−１）高分子量ＳｉＯ₂ゾル溶液の調整：撹拌機、窒素導入管、排出管を装備した四つ口フラスコに、メチルトリメトキシシラン（ＭＴＭＯＳ）２２．７ｇ（０．１７ｍｏｌ）とメタノール１４ｍｌを加えて混合し、０℃に冷却した。これと水と塩酸とを、各々、Ｈ₂Ｏ／ＭＴＭＯＳ＝１．３０、ＨＣｌ／ＭＴＭＯＳ＝０．１０５となる様に添加して、室温で１０分間撹拌した後、乾燥窒素を導入しながら７０℃で３時間、１５０ｒｐｍの速度で撹拌した後、減圧下で溶媒を留去して、高粘性の重合物からなる高分子量体を得た。
この高分子量体がＭｅＳｉＯ_1.5（但し、Ｍｅはメチル基）に加水分解及び縮合したと仮定したときの固形分濃度が１．５質量％になる様に、該高分子量体をメチルエチルケトンに溶解し、高分子量ＳｉＯ₂ゾル液を得た。
この高分子量体の分子量は、ポリスチレンを標準試料として、ＧＰＣ（ゲル浸透クロマトグラフ）により測定したところ、重量平均分子量で４２０００であった。
【００８８】
（２−２）低分子量ＳｉＯ２ゾル溶液の調整：メチルトリエトキシシラン（ＭＴＥＯＳ）が理想的にＳｉＯ₂又はＭｅＳｉＯ_1.5に加水分解及び縮合したと仮定したときの固形分濃度が３重量％となる様に、ＭＴＥＯＳを溶媒であるメチルエチルケトンに溶解し、液温が２５℃に安定するまで３０分撹拌した。次に、触媒として濃度０．００５Ｎの塩酸をＭＴＥＯＳのアルコキシ基と等モル量を添加して、２５℃で３時間、加水分解反応を行った。次に、硬化剤として酢酸ナトリウムと酢酸を混合したものを添加して、２５℃で１時間撹拌して、低分子量ＳｉＯ２ゾル溶液を得た。
【００８９】
（３）ゾルゲル液の調整：上記低分子量ＳｉＯ₂ゾル溶液に、前記高分子量ＳｉＯ₂ゾル溶液を３０質量％添加して、塗布用のゾルゲル液とした。
【００９０】
（４）塗布膜の形成及び賦型：厚さ２５０μｍのポリエチレンテレフタレートシートからなる基材の表面に上記ゾルゲル液を、溶剤除去後の膜厚が、１０ミクロンとなる様に塗布し、６０℃で５分間乾燥して塗布膜とした。次いで、前記（１）の賦形型を用いて、熱プレス法にて該塗布膜の表面に所望の微細凹凸を賦型した。すなわち、ＳｉＯ₂層を塗布形成した基材に賦形型を〔１２０℃、１Ｐａ（１０ｋｇｆ／ｃｍ²）〕の熱圧条件で押圧した。その結果、賦形型を剥離して得られた基材上の塗布膜表面には、賦形型の逆凹凸パターンが形成され、所望の微細凹凸を表面に有する微細凹凸層となり、該微細凹凸層が基材上に積層された構成の透明な反射防止物品が得られた。
【００９１】
上記微細凹凸層を基材表面に有する反射防止物品について、反射率を測定したところ、視感反射率は０．３％と反射防止効果が認められた。
【００９２】
〔実施例２〕
次の様にして、賦形型、ゾルゲル液を用意して、図１（Ｅ）の如き表面に微細凹凸２を有する微細凹凸層３が、基材１上に積層された構成の透明な反射防止物品１０を作製した。
【００９３】
（１）賦形型の作製：石英ガラス基板の片面に金属クロム膜を形成した後、その上にポジ型レジストをスピンコートしてレジスト膜を形成した。次いで、このレジス膜に、縦横周期３００ｎｍのメッシュ状描画データを電子線描画装置にて描画後、現像液で現像し、前記メッシュ開口領域が開口したレジストパターン層を形成した。次いで、該レジストパターン層の開口部から露出している金属クロム膜を塩素系ガスでドライエッチングした。そして、レジストパターン層と金属クロム膜を耐エッチング層として、ガラス基板をフッ素系ガスでドライエッチングして、所望の微細凹凸形状が造形された原型（マザー版）を作製した。次に、この原型から、電気めっき法によって、厚さ８０μｍのニッケルめっきプレートからなる複製型（ニッケルスタンパ）を賦形型として作製した。
【００９４】
（２）ゾルゲル液の作製：ゾルゲル液としては、高分子量ＳｉＯ₂ゾル溶液と、低分子量ＳｉＯ₂ゾル溶液とを各々調整し、これらを混合して作製した。
【００９５】
（２−１）高分子量ＳｉＯ₂ゾル溶液の調整：撹拌機、窒素導入管、排出管液を装備した四つ口フラスコに、メチルトリメトキシシラン（ＭＴＭＯＳ）２２．７ｇ（０．１７ｍｏｌ）とメタノール１４ｍｌを加えて混合し、０℃に冷却した。これと水と塩酸とを、各々、Ｈ₂Ｏ／ＭＴＭＯＳ＝１．３０、ＨＣｌ／ＭＴＭＯＳ＝０．１０５となる様に添加して、室温で１０分間撹拌した後、乾燥窒素を導入しながら７０℃で３時間、１５０ｒｐｍの速度で撹拌した後、減圧下で溶媒を留去して、高粘性の重合物からなる高分子量体を得た。
この高分子量体がＭｅＳｉＯ_1.5に加水分解及び縮合したと仮定したときの固形分濃度が１．５質量％になる様に、該高分子量体をメチルエチルケトンに溶解し、高分子量ＳｉＯ₂ゾル液を得た。
この高分子量体の分子量は、ポリスチレンを標準試料として、ＧＰＣ（ゲル浸透クロマトグラフ）により測定したところ、重量平均分子量で４２０００であった。
【００９６】
（２−２）低分子量ＳｉＯ２ゾル溶液の調整：メチルトリエトキシシラン（ＭＴＥＯＳ）が理想的にＳｉＯ₂又はＭｅＳｉＯ_1.5（但し、Ｍｅはメチル基）に加水分解及び縮合したと仮定したときの固形分濃度が３重量％となる様に、ＭＴＥＯＳを溶媒であるメチルエチルケトンに溶解し、液温が２５℃に安定するまで３０分撹拌した。次に、触媒として濃度０．００５Ｎの塩酸をＭＴＥＯＳのアルコキシ基と等モル量添加して、２５℃で３時間、加水分解反応を行った。次に、硬化剤として酢酸ナトリウムと酢酸を混合したものを添加して、２５℃で１時間撹拌して、低分子量ＳｉＯ２ゾル溶液を得た。
【００９７】
（３）ゾルゲル液の調整：上記低分子量ＳｉＯ₂ゾル溶液に、前記高分子量ＳｉＯ₂ゾル溶液を３０質量％添加し、さらにこの添加後の溶液に対して、ポリエチレングリコールを５質量％添加したものを、塗布用のゾルゲル液とした。
【００９８】
（４）塗布膜の形成及び賦型：厚さ２ｍｍのガラス製の基材の表面に上記ゾルゲル液を、溶剤除去後の膜厚が、１０ミクロンとなる様に塗布し、６０℃で５分間乾燥して塗布膜とした。次いで、前記（１）の賦形型を用いて、熱プレス法にて該塗布膜の表面に所望の微細凹凸を賦型した。すなわち、ＳｉＯ₂層を塗布形成した基材に賦形型を〔１２０℃、１Ｐａ（１０ｋｇｆ／ｃｍ²）〕の熱圧条件で押圧した。その結果、賦形型を剥離して得られた基材上の塗布膜表面には、賦形型の逆凹凸パターンが形成され、所望の微細凹凸を表面に有する微細凹凸層となったた。更に、賦形型を剥離した後、該微細凹凸層を４５０℃で３０分焼成して、最終的な微細凹凸層として、所望の反射防止物品を得た。
【００９９】
上記微細凹凸層を基材表面に有する反射防止物品について、反射率を測定したところ、視感反射率は０．５％と反射防止効果が認められた。
【０１００】
【発明の効果】
（１）本発明の反射防止物品の製造方法によれば、反射防止物品の表面の微細凹凸はフォトレジスト塗布・露光・現像等によって、一品毎に直接造形する場合に比べて、一旦賦形型を作製した後、この賦形型からの賦形によって形成できるので、生産性が良い。しかも、表面に形成する微細凹凸層は、ゾルゲル法によって形成する為に、無機質系の層が得られ、例えば２Ｐ法等による樹脂層として形成する場合に比べて、耐熱性、耐候性等を優れたものとできる。また、微細凹凸の硬度も得られ、耐洗浄性等も良くなる。また、賦形後の微細凹凸層の焼成を行わない場合には、基材にはガラス等の無機材料以外に樹脂等の耐熱性に乏しい有機材料も可能となる。しかも、時間がかかる焼成工程が無い点で生産性が良く、例えば樹脂シート等の連続帯状の基材に対して、連続処理により更に生産性を良くする事も可能となる。
また、本発明の製造方法で反射防止物品に付与される反射防止機能は、梨地処理等の様な鏡面乱反射によって光反射を低減するものでは無く、物品表面と空気との界面の急激な屈折率変化を緩和する事によって実現している為に、光反射率が低減した分、光透過率が向上する。従って、ディスプレイ等の情報表示部の窓材等に使用時に、表示の視認性を向上させると共に、表示光の光の利用効率も上げられる反射防止物品が得られる。
【０１０１】
（２）また、基材を無機質基材とし、微細凹凸層を焼成する様にすれば、微細凹凸層が有機質成分を含む場合であっても、有機質成分を燃焼、消失させて無機質層とすることができ、耐熱性、耐候性、硬度、耐洗浄性等はより確実に優れたものとできる。従って、例えば、微細凹凸の上に更にＩＴＯ膜等の透明導電膜を物理的手法により形成する場合等の耐熱性が要求される後処理も容易にできる様になる。
【図面の簡単な説明】
【図１】本発明の反射防止物品の製造方法をその一形態で概念的に説明する説明図。
【図２】微細凹凸で得られる有効屈折率の分布を概念的に説明する為の図（その１）。
【図３】微細凹凸で得られる有効屈折率の分布を概念的に説明する為の図（その２）。
【図４】微細凹凸で得られる有効屈折率の分布を概念的に説明する為の図（その３）。
【図５】微細凹凸の（垂直）断面形状の幾つかを例示する断面図。
【図６】微細凹凸の水平面内での配置の幾つかを例示する断面図。
【符号の説明】
１ 基材
２ 微細凹凸
２Ａ （賦形型上の）微細凹凸
２ｔ （微細凹凸２の）最凸部
３Ａ （賦形前の）塗布膜
３ 微細凹凸層
１０ 反射防止物品
４０ 原型
４１ 賦形型（複製型）
ｎ 屈折率
ｎ_a 屈折率（空気）
ｎ_b 屈折率（基材）
ｎ₀ 屈折率
ｎ₁ 屈折率
ｎ_ef（Ｚ） 有効屈折率
Ｈ_MIN （微細凹凸の）最小高さ
Ｐ_MAX 周期
Ｒ 反射率
λ_MIN 最小波長
λ_MAX 最大波長[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an antireflective material that prevents surface reflection of light, which can be used in various applications such as a liquid crystal display unit of a cellular phone.GoodsIt relates to a manufacturing method. In particular, an anti-reflective material provided with an anti-reflection function by a sol-gel methodGoodsIt relates to a manufacturing method.
[0002]
[Prior art]
Articles that have been antireflective or desired to be antireflective are found in a variety of applications. For example, it is a window material of an information display section of various devices. For example, in mobile phones, digital cameras, etc., in order to protect the information display unit using a liquid crystal display (LCD) from water, dust, external force, etc., the display panel by LCD etc. is directly outside the device. In many cases, the display panel is protected by providing a window material made of a transparent plastic plate or the like outside without exposing it (see JP-A-7-66859, etc.).
[0003]
[Problems to be solved by the invention]
However, when a window member or the like is disposed in front of the display panel, there is a problem that external light is reflected on both the front and back surfaces of the window member, and display visibility is lowered. In addition, in portable devices such as mobile phones, in which low power consumption of the display panel is an important factor, the display panel is further affected by the light reflection at the window material in addition to the decrease in display visibility as a problem of external light reflection. Since a part of the light from the light is returned to the display panel, the light use efficiency of the display panel is lowered, and there is a problem that wasteful power is consumed correspondingly.
The window material described above is an example of an antireflection article. In addition to this, as an article for which light reflection prevention is desired or necessary, for example, various optical components, a transparent touch panel, or the front of an advertisement display. There are various types such as protective plates.
[0004]
As a conventional antireflection treatment technique, for example, a reflection made of a low refractive index layer single layer film or a multilayer film of a low refractive index layer and a high refractive index layer by a technique such as vapor deposition, sputtering, or coating. Techniques such as providing a prevention layer (see JP 2001-127852 A) are common. However, since the antireflection layer by vapor deposition, sputtering, etc. needs to form a thin film with a controlled refractive index and thickness by one or many batch processes, there is a problem in product stability, yield rate, etc. In addition, since batch production is used, productivity is low, and there is a problem that costs are increased.
Alternatively, as another antireflection treatment, there is a technique in which the surface is treated with a satin finish, and the specular reflection light is reduced by the diffuse (diffuse) reflection. However, in this method, the light use efficiency is improved in that the light is diffused. There is a problem that the resolution of an image that can not be increased and the image seen through is reduced. This is, for example, the utilization efficiency of the display light of the display panel in the window material of the information display section.
[0005]
In order to solve these problems in the conventional antireflection processing technology, the present applicant has disclosed a very fine microscopic structure having a repetition period equal to or less than the wavelength of light as disclosed in JP-A-50-70040. An attempt was made to apply a technique for reducing surface reflectance by providing irregularities on the surface. The technique disclosed in the publication will be described here. For an optical component such as a lens whose surface reflection should be reduced, a photoresist pattern is applied to the surface, exposed, developed, etc. Is produced, and the glass substrate is corroded with the pattern, whereby fine irregularities are directly formed on the surface of the optical component for each product.
However, in the production of each product, there is a problem that work efficiency is poor and productivity (mass productivity) necessary for industrial products cannot be obtained.
[0006]
From such a point of view, the present inventors used a replication type as Japanese Patent Application No. 2001-352675 (unpublished at the time of filing of the present invention) and finely formed on the substrate by the so-called 2P method (Photo-polymerization method). A method of shaping the uneven layer was proposed. According to this method, the productivity is improved. However, as long as the 2P method is used, the fine uneven layer formed on the surface of the obtained antireflection article is made of an organic material called a photocurable resin. It cannot be denied that heat resistance, weather resistance and the like are limited as compared with the case of materials.
[0007]
  That is, an object of the present invention is to reduce the useless reflection of light, improve the visibility of the display, and improve the visibility of the display light and increase the use efficiency of the light of the display. It is to provide a good manufacturing method. Moreover, it is to provide a production method that also improves heat resistance and weather resistance..
[0008]
[Means for Solving the Problems]
Therefore, in order to solve the above-mentioned problems, the method for producing an antireflection article according to the present invention is a method for producing an antireflection article having a fine concavo-convex layer having antireflective fine undulations on the surface. The fine irregularities have a minimum wavelength λ in a vacuum in the visible light wavelength band._MIN, The period at the most convex part of the fine irregularities is P_MAXAnd when
P_MAX≦ λ_MIN
Have the relationship
And the cross-sectional area occupation rate of the material part of the base material in the cross section when it is assumed that the fine unevenness is cut by a plane orthogonal to the unevenness direction, goes from the most convex portion of the fine unevenness to the most concave portion. It is unevenness that gradually increases gradually,
In order to manufacture the antireflection article, as a step, (A) First, a prototype in which fine irregularities are formed is prepared, and (B), then, the prototype is used as a shaping mold, or the surface of the prototype A replica mold is produced by replicating the fine concavo-convex shape one or more times by molding or reversing one or more times, and using the replica mold, a coating film of a sol-gel solution containing an organometallic compound formed on a substrate is formed. On the other hand, after pressing the shaping mold, it is released from the mold, and the surface of the coating film is shaped into fine irregularities to form a fine irregularity layer. I did it.
[0009]
By making such a manufacturing method, the fine unevenness on the surface of the antireflection article is once formed by a shaping mold, compared with the case of directly shaping each article by photoresist coating / exposure / development, etc. Since it can be formed by shaping from a shaping mold, productivity is improved first. In other words, even if it takes a long time to produce a prototype for first shaping a fine concavo-convex shape, once the prototype is produced, the shaping mold can be used repeatedly even if it is used as it is as a shaping mold. is there. In addition, if the original mold is not used as a shaping mold, but a replica mold obtained by copying and reversing the fine irregularities from the original mold is used as the shaping mold, the productivity is further improved. This is because a duplicated type can be manufactured in parallel by preparing many of the same, and even if the duplicated type is damaged, it is not necessary to recreate it from the original type. These productivity improvement effects can be obtained because the process of producing a prototype by a photolithography method or the like is the most difficult, and the time, labor, and manufacturing cost are large.
[0010]
Moreover, in the production method of the present invention, the fine uneven layer formed on the surface of the antireflection article is formed by a sol-gel method using an organometallic compound as a starting material, so that an inorganic layer is obtained. Compared with the case where it is formed as a resin layer, the heat resistance, weather resistance and the like can be improved. Further, the hardness of the fine irregularities can be obtained, and the washing resistance is improved.
In addition, in the manufacturing method of this invention, although a fine uneven | corrugated layer may be baked, it is not necessary to bake. In addition, when not firing, the base material of the anti-reflective article can be an organic material with poor heat resistance, such as a resin, as well as an inorganic material such as glass. For example, productivity can be further improved by continuous treatment for a continuous belt-like base material such as a resin sheet.
[0011]
It is to be noted that light reflection is prevented by the fine unevenness. Simply speaking, if a fine unevenness having a size equal to or smaller than the wavelength of the light to be prevented from reflection is provided on the material surface, the refractive index change between the surface and air This is because light reflection, which is a phenomenon that occurs when the refractive index changes rapidly and discontinuously, can be prevented.
[0012]
Moreover, the antireflection function of the antireflection article provided with such fine irregularities is not a light diffusive antireflection that reduces specular reflection light due to irregular reflection such as a satin treatment, but an antireflection function between the article surface and air. Since it is realized by mitigating a sudden change in refractive index at the interface, it is non-light diffusive, and the light transmittance is improved as much as the light reflectance is reduced. Therefore, when used for a window material of an information display unit such as a display, the visibility of display is improved and the use efficiency of light of display light is improved.
[0013]
The antireflection article manufacturing method of the present invention is the above-described manufacturing method, wherein the base material is an inorganic base material, and the fine unevenness is formed on the surface after releasing the shaping mold. The production method was such that the layer was fired.
[0014]
This production method is further limited to a form in which the base material is an inorganic base material and includes a firing step as a production process. By using such a production method, the fine uneven layer contains an organic component. However, the organic component can be burned and eliminated to form an inorganic layer, and the heat resistance, weather resistance, hardness, washing resistance, etc. can be more reliably improved. Therefore, for example, post-processing that requires heat resistance such as when a transparent conductive film such as an ITO film is further formed on the fine irregularities by a physical method can be easily performed.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0018]
〔Overview〕
FIG. 1 is an explanatory view (sectional view) conceptually explaining, in one form, a method for producing an antireflection article by the sol-gel method according to the present invention. In the embodiment described here, the original mold is not used as the shaping mold as it is, but the replica mold is temporarily duplicated from the original mold, and this duplicate mold is used as the shaping mold.
[0019]
First, as shown in FIG. 1A on the upper right side of the drawing, a shaping die 41 for shaping fine irregularities has fine irregularities 2A having a concave and convex shape opposite to the fine irregularities 2 to be imparted to the antireflection article on the shaping surface. Have As the shaping mold 41, more preferably from the viewpoint of productivity, as shown in FIG. 1 (B) on the upper left side of the drawing, an original mold formed with a fine concavo-convex shape (form the fine concavo-convex shape first) by an exposure method or the like. Instead of using 40, as shown in FIG. 1C, it is preferable to use as a shaping mold 41 a replication mold obtained by duplicating a fine concavo-convex shape from the original mold 40 by molding and reversal. Of course, if there is no problem in terms of productivity or the like, the prototype 40 may be used as the shaping die 41 as it is.
[0020]
As shown in FIG. 1A, a coating film 3A is formed on the substrate 1 by applying a sol-gel solution containing an organometallic compound. 1D, after pressing the coating film 3A with the shaping mold 41 and then releasing the shaping mold 41, the coating film 3A has its surface as shown in FIG. The anti-reflective article 10 of the structure by which the fine uneven | corrugated layer 3 by which the fine unevenness | corrugation 2 was shaped into the fine uneven | corrugated layer 3 was laminated | stacked on the base material 1 is obtained.
[0021]
Even in this state, the surface of the antireflective article 10 has a fine unevenness 2 having a desired uneven shape, so that an antireflection effect can be obtained. However, the strength of the fine unevenness layer 3 having the fine unevenness 2 on the surface can be obtained. In order to improve durability and the like, it is preferable to burn the organic component in the fine uneven layer 3 through a firing step. In the case of firing, of course, the base material becomes a material that can withstand the firing temperature, which is suitable when the base material is an inorganic material such as glass.
[0022]
The fine unevenness 2 unique to the present invention is a conventionally known antireflection treatment or prevention of a system in which light is scattered (diffuse reflection) by using a mat surface (matte) formed by unevenness having a size greater than or equal to the light wavelength. Unlike the glare treatment, the unevenness is a shape unique to the present invention having a size equal to or smaller than the wavelength of visible light. Such fine irregularities provide an anti-reflection effect.
[0023]
Since FIG. 1 is conceptual, the shape of the antireflective article 10 is a flat plate, but the shape is not limited to a flat plate. The fine irregularities 2 can also be formed on two or more surfaces of the antireflection article.
[0024]
In addition, in the antireflection article and the shaping mold, the fine irregularities have a reverse irregularity relationship, but in the explanation of the present invention, when these fine irregularities are specifically distinguished, those on the antireflection article are The fine irregularities 2 and those on the shaping mold are properly used as the fine irregularities 2A depending on the difference in the reference numerals. However, in the shaping mold by the replication mold, the fine irregularities between the shaping mold and the original mold may or may not be in the reverse irregularity relationship depending on the number of duplication operations by mold making / reversing to obtain it. is there. When the duplication operation is one time or an odd number, the shaping mold and the original pattern have a reverse uneven relationship, but when the duplication operation is two times or an even number, they have the same uneven relationship.
[0025]
[Fine unevenness]
The fine irregularities 2 have an antireflection effect for the following reason.
That is, by the fine unevenness 2, a sudden and discontinuous refractive index change between the fine uneven layer 3 constituting the surface of the antireflection article and the outside (air) is changed into a continuous and gradually changing refractive index change. It is possible to change. Since light reflection is a phenomenon caused by a sudden and rapid change in the refractive index of the material interface, the refractive index change on the surface of the article is changed spatially and continuously. Light reflection on the surface of the article is reduced.
In addition, although the fine uneven | corrugated layer 3 becomes a thing which is normally transparent and permeate | transmits light, even if it is an opaque thing, the reflection preventing effect which reduces the surface reflection is acquired.
[0026]
Hereinafter, the reason why the antireflection effect is obtained by the fine unevenness 2 formed on the surface of the fine unevenness layer 3 will be described in detail on the assumption that the fine unevenness layer 3 (and the substrate 1) is transparent.
[0027]
2 to 4 are conceptual diagrams for conceptually explaining the refractive index distribution obtained by the fine unevenness 2 formed on the surface of the fine unevenness layer 3. First, FIG. 2 shows an example of a fine concavo-convex layer 3 laminated on a substrate 1 (not shown) as an antireflection article and provided with fine concavo-convex 2 on the surface. A state is shown in which a large number of fine unevennesses 2 having the Z-axis direction as the unevenness direction are arranged on the surface of the fine unevenness layer, that is, the XY plane at Z = 0.
[0028]
In the present invention, the fine unevenness 2 is set to P as the period at the most convex portion 2t as shown in FIG._MAXWhen this P_MAXIs the minimum wavelength in vacuum in the visible light wavelength band._MINBecause of the following, for the light reaching the surface with fine irregularities, even if there is a spatial distribution in the refractive index of the medium (fine irregularities layer and air), it is a distribution with a size below the wavelength of interest. Therefore, the distribution does not act directly on the light, but acts as an average. Therefore, if the distribution is such that the averaged refractive index (effective refractive index) changes continuously as the light travels, reflection of light can be prevented.
[0029]
In the present invention, the period P at the most convex part 2t._MAXIs the maximum distance between the most convex portions 2t of the adjacent fine irregularities 2, and each fine irregularity is regularly arranged and has periodicity (the distance between adjacent fine irregularities is the same). ) Structure, but may have a structure with no periodicity (the distance between adjacent fine irregularities is not uniform).
[0030]
In FIG. 2, as the orthogonal coordinate system, the Z axis is taken in the normal direction standing on the envelope surface of the surface of the fine concavo-convex layer 3, and the X axis and the Y axis are taken in a plane perpendicular thereto. And now, light enters the fine concavo-convex layer from the outside of the fine concavo-convex layer, proceeds inside the fine concavo-convex layer, and is proceeding near the surface of the fine concavo-convex layer in the negative direction of the Z-axis, It is assumed that the Z-axis coordinate exists at z.
[0031]
Then, for the light at Z = z here, the refractive index of the medium is such that the surface of the fine concavo-convex layer 3 forms specific fine concavo-convex 2, strictly speaking, the XY plane perpendicular to the Z axis at Z = z. In (cross section: horizontal section), it appears to have a distribution f (x, y, z). That is, in the XY plane, the cross-sectional portion of the fine uneven layer 3 has a refractive index n._b(About 1.5), the other part, specifically the part of air a is the refractive index n_a(= About 1.0) (see FIG. 3).
However, in practice, for light, the wavelength (if the wavelength of the light to be prevented from being reflected has a distribution, the minimum wavelength λ of the wavelength band)_MINThink about it. As a result, the effective refractive index of the averaged result is the refractive index distribution f (x, y) in the XY plane. , Z) integrated in the XY plane,
[0032]
[Expression 1]

[0033]
It becomes. As a result, the effective refractive index (n_ef) Distribution is a function n of z only_ef(Z) (see FIG. 4).
[0034]
Therefore, if the cross-sectional area of the convex portion of the fine concavo-convex layer 3 in the fine concavo-convex portion 2 is a shape that continuously increases toward the concave portion, the fine concavo-convex layer portion (in the XY plane) Since the area ratio with the air portion continuously changes in the Z-axis direction, the effective refractive index n_ef(Z) is a continuous function for z.
[0035]
On the other hand, in general, the refractive index n₀From the medium of the refractive index n₁Consider the case where light is incident on the medium. For the sake of simplicity, consider an incident angle θ = 0 ° (normal incidence). However, the incident angle is an angle with respect to the normal of the incident surface.
In this case, the reflectance R at the medium interface does not depend on the polarization and the incident angle, and is expressed by the following [Equation 2].
[0036]
[Expression 2]

[0037]
Therefore, the fact that the (effective) change in the refractive index in the Z direction is a continuous function means that the refractive index n at Z = z, two points separated by a small distance Δz in the Z direction (light traveling direction)._ef(Z) to n₀, Refractive index n at Z = z + Δz_ef(Z + Δz) is n₁, And when
[0038]
If Δz → 0, n₁→ n₀
[0039]
(From the definition of the continuous function)
[0040]
R → 0
[0041]
It becomes.
[0042]
Strictly speaking, the wavelength of light in the object is λ / n where λ is the wavelength in vacuum and n is the refractive index of the object. Become small. However, since the refractive index when the object is air is n≈1, it can be considered that λ / n≈λ. However, since the material used for the fine uneven layer usually has a refractive index of around 1.5, the refractive index n_bWavelength in the substrate (λ / n_b) Is about 0.7λ. Considering this point, in the portion of the fine unevenness 2, when looking at the air side portion (the concave portion of the fine unevenness 2),
[0043]
P_MAX≦ λ_MIN
[0044]
When the above condition is satisfied, the effect of reducing the reflectance by averaging the refractive index can be expected. However,
[0045]
λ_MIN/ N_b≦ P_MAX≦ λ_MIN
[0046]
In this case, if the contribution of the portion of the fine concavo-convex layer (the convex portion of the fine concavo-convex 2) is seen, the reflectance reduction effect by the refractive index averaging cannot be expected at least completely.
However, it still has an anti-reflection effect as a whole because of its contribution in the air portion.
And
[0047]
P_MAX≦ λ_MIN/ N_b
[0048]
When the above condition is satisfied, both the air portion and the fine uneven layer portion have a period P_MAXHowever, since the condition that the wavelength is smaller than the shortest wavelength is completely satisfied, the antireflection effect by the refractive index averaging becomes more complete.
Specifically, λ_MINThe lower limit of the visible light wavelength band is 380 nm, n_bIs 1.5, λ_MIN/ N_bIs 250 nm, ie P_MAXMay be 250 nm or less.
[0049]
Next, the shape of the fine unevenness 2 is the cross-sectional area of the material portion of the fine unevenness layer in the cross section (horizontal cross section) when it is assumed that the fine unevenness is cut by a plane (XY plane) perpendicular to the uneven direction. The occupancy rate has a shape that gradually and gradually increases from the most convex part (top) of the fine unevenness to the most concave part (valley bottom). For this purpose, at least a part of the ridges of the fine irregularities may have an inclined slope. good. In particular, the shape is preferably such that it completely converges to 0 at the most convex portion and completely converges to 1 at the most concave portion. Specifically, for example, shapes as shown in FIGS. 5B and 5C can be given. However, as shown in FIG. 5 (D) or FIG. 5 (E), the shape of the most convex portion asymptotically approaches 0 or the shape of the most concave portion asymptotically approaches 1 may be used. Some effect can be obtained. The shape of the fine irregularities may be any shape as long as these conditions are satisfied.
[0050]
For example, the vertical cross-sectional shape of each fine unevenness 2 is a wave-like shape only by a curve such as a sine wave as shown in FIG. 5 (A) (see also FIG. 2), as shown in FIG. 5 (B) and FIG. 5 (C). A shape formed only by a straight line such as a triangle, or a trapezoidal shape in which the most convex part of the triangle forms a flat surface as shown in FIG. 5D, and the most concave part between adjacent triangles as shown in FIG. The shape of the surface. However, as shown in FIG. 5D and FIG. 5E, in the shape having a flat surface in the most convex portion or the most concave portion, the area ratio occupied by the flat surface in the flat surface portion of the most convex portion or the most concave portion. The larger the is, the greater the change in effective refractive index becomes discontinuous. In that respect, performance is inferior. However, even in this case, the effective refractive index can be continuously changed from the most convex part of the fine unevenness to the most concave part. Therefore, in terms of antireflection performance, the smaller the area ratio of the flat surface of the most convex part or the most concave part, the better.
[0051]
Effective refractive index n_ef(Z) as a function in the Z direction from air into the fine relief layer, n_aTo n_b5B or 5C, the cross-sectional area occupancy of the fine concavo-convex layer converges to 0 at the most convex part of the fine concavo-convex. It is most preferable that the cross-sectional area occupancy continuously converges to 1 in the most concave portion (that is, a sharp shape).
[0052]
Next, the horizontal sectional shape of each fine unevenness is arbitrary such as a circle (for example, FIG. 2), an ellipse, a triangle, a quadrangle, a rectangle, a hexagon, and other polygons. The horizontal cross-sectional shape does not have to be the same from the most convex part to the most concave part of the fine irregularities. Therefore, the three-dimensional shape of the fine unevenness is, for example, a fine three-dimensional shape of the fine unevenness when the horizontal cross-sectional shape is circular and the vertical cross-sectional shape is equilateral triangle, and the fine shape when the horizontal cross-sectional shape is circular and the vertical cross-sectional shape is triangular. The three-dimensional shape of the unevenness is an oblique cone, the three-dimensional shape of the fine unevenness is a triangular pyramid when the horizontal cross-sectional shape is triangular and the vertical cross-sectional shape is an equilateral triangle, and the fine unevenness when the horizontal cross-sectional shape is quadrilateral and the vertical cross-sectional shape is a triangular shape The three-dimensional shape becomes a quadrangular pyramid.
[0053]
Further, the arrangement of the fine irregularities in the horizontal plane is not limited to the two-dimensional arrangement as illustrated in FIG. 2, but also as the linear groove-shaped fine irregularities 2 illustrated in the perspective view of FIG. The original arrangement may be used, and both are effective. However, in the case of the one-dimensional arrangement, anisotropy occurs in which a direction in which an antireflection effect is obtained and a direction in which the antireflection effect is not obtained are generated in relation to the amplitude direction of the light wave. Accordingly, the two-dimensional arrangement illustrated in the perspective view of FIG. 2 and the plan views of FIGS. 6B and 6C is preferable in that there is no directivity.
[0054]
In addition, although all the solid shapes of each fine unevenness | corrugation may be the same, it does not need to be all the same. In addition, when the individual fine irregularities 2 are two-dimensionally arranged, the period may be the same for each fine irregularity, or not all.
[0055]
Further, the height H of the fine unevenness is determined according to the desired reflectance reduction effect and the maximum wavelength of the visible light band incident on the surface of the fine uneven layer. For example, when designing based on the relationship described in Japanese Patent Laid-Open No. 50-70040 (particularly, FIG. 3 thereof) with the reflectance, the height of fine irregularities, and the light wavelength, for example, the reflectance in the visible light band If the goal is to reduce it to 2% (half of untreated glass) or less, its minimum height H_MINIs 0.2λ_MAXThat is,
[0056]
H_MIN≧ 0.2λ_MAX
[0057]
If the goal is to reduce the reflectance in the visible light band to 0.5% or less,
[0058]
H_MIN≧ 0.4λ_MAX
[0059]
Is preferable. Where λ_MAXIs the maximum wavelength in a vacuum in the visible light wavelength band. Although the reflectance decreases as the height H of the fine irregularities increases from zero, a significant effect can be obtained when the height reaches a height that satisfies the above inequality condition. Specifically, for example, the maximum wavelength of the emission spectrum is λ_MAX= If a fluorescent lamp of 640 nm is used, H_MIN≧ 0.2λ_MAX= 128 nm. That is, H_MINMay be 128 nm or more. The maximum wavelength of the spectrum is λ_MAX= If you consider 780nm sunlight, H_MIN≧ 0.2λ_MAX= 156 nm, ie H_MINMay be 156 nm or more. Minimum height H_MINAnd period P_MAXThe minimum height H_MIN/ Cycle P_MAXThe ratio is about 1/2 to 4/1.
[0060]
Here, as an example of the specific shape and size of the fine irregularities, the shape is an aggregate of two-dimensional regular arrangements of many conical shapes whose vertical cross section is sinusoidal and whose horizontal cross section is circular. Yes, period P_MAX50-250nm, minimum height H_MINThe period P_MAXThere are some that are 1.5 times larger.
[0061]
[Production of shaping mold]
As a shaping mold used for shaping a coating film by the sol-gel method, a prototype in which a fine concavo-convex shape is first shaped may be used, but in terms of productivity, more preferably, once from the prototype. Alternatively, it is preferable to use a replication mold produced through a replication process by two or more molds and inversions. In other words, after first producing a prototype (also referred to as a master plate or a mother plate), a duplication operation for creating a replica mold from this master mold is performed once or twice or more, and the result is obtained. The replication type (which is also referred to as the main plate or the master plate) is adopted as a shaping type used for the coating film by the sol-gel method. By setting it as such a method, it becomes a method excellent in industrial productivity, cost, etc.
[0062]
The original mold for the shaping mold is not particularly limited as long as necessary fine irregularities are formed, and it is appropriately determined in consideration of productivity, cost, etc. What is necessary is just to use. The production of the prototype is a process of first forming an uneven shape for shaping the fine unevenness 2 and is a so-called microfabrication technique in the semiconductor field or the like, that is, so-called utilizing light (including electron beam) for pattern formation. An exposure method can be used. However, in the case of a semiconductor, the side surface of the concavo-convex shape may be a normal vertical surface, and it is not particularly necessary to have a slope as in the present invention. Therefore, in the present invention, fine processing is performed so that a slope can be formed.
[0063]
As the fine processing technique as described above, an electron beam drawing method can be used. In this method, first, a resist layer is formed on a glass substrate, and then the resist layer is exposed and developed by an electron beam drawing method and patterned to form a resist pattern layer. Thereafter, by using the resist pattern layer as a corrosion mask and corroding the glass substrate by a dry etching method or the like, a fine uneven shape is formed on the glass substrate. At this time, side etching is performed at the time of etching to form a slope. In addition, the resist pattern layer itself may be used directly as a corrosion mask when the glass substrate is corroded, but in order to form a deep uneven shape having a slope, a metal layer made of chromium or the like is preferably provided on the glass substrate. Thereafter, a resist film is formed to obtain a resist pattern layer, and the metal layer is formed as a metal pattern layer using the resist pattern layer, and it is preferable to use it as a corrosion mask.
[0064]
In forming a pattern on the resist film, a laser drawing method can be used in addition to the electron beam drawing method. In the laser drawing method, a laser interference method used for producing a hologram, a diffraction grating, or the like can be used. In the case of a diffraction grating, it is a one-dimensional arrangement, but a two-dimensional arrangement is also possible if multiple exposures are performed at different angles. However, in the laser interferometry, the fine irregularities obtained are usually regularly arranged. However, in the electron beam drawing method, predetermined drawing pattern information is stored as digital data in a storage device in advance, and the drawing pattern information is used. , Modulates ON / OFF or intensity of the scanning electron beam. Therefore, in addition to the regular arrangement, irregular arrangement is also possible. Further, since the laser drawing method and the electron beam drawing method each have advantages and disadvantages, appropriate methods and conditions are selected in consideration of design specifications, purpose, productivity, and the like.
[0065]
Next, as a method for producing a replication mold to be used as a shaping mold from the above-mentioned prototype, a metal replication mold can be obtained by performing a known method, for example, by performing metal plating of nickel or the like on the prototype and removing the plating layer. Can be produced (electroforming method). Alternatively, the shaping mold may be produced through two or more times of duplication operations, such as plating this replication mold once again and making the duplicated mold a shaping mold. In addition, as a form of the shaping type | mold with respect to the coating film formed by the sol-gel method, there may be plate shape, sheet shape, block shape, etc., and what is necessary is just to select suitably according to the shape, use, etc. of an antireflection article. The shaping mold may be made of metal such as nickel, but may be made of resin such as silicone resin. For example, it is a shaping type that can be formed into a continuous sheet with a resin sheet.
[0066]
[Sol-gel method]
By the way, the sol-gel method is known as a method for forming an inorganic coating film made of a metal oxide from a coating film in which a sol-gel liquid containing an organometallic compound such as alkoxysilane as a metal oxide precursor is coated on a substrate. It has been. Recently, it is also known as a method for forming an organic-inorganic composite film. In these sol-gel methods, when the base material is a resin sheet, etc., a baking process is not included, in which the coating film is heat-treated at a high temperature to burn / disappear organic components, but when the base material is an inorganic material such as glass In addition, since the substrate can withstand high heat, the coating film can be further baked to form a complete inorganic film.
[0067]
As a method for forming a concavo-convex shape on the surface of such a coating film by the sol-gel method, for example, JP-A-62-225273, JP-A-6-94907, or “sol-gel method” "Micropatterning" (Ceramics, vol 37, No. 3, p161-164, 2002). According to these documents, a shaping mold is pressed against a plastic coating film formed by applying a sol-gel solution containing a metal alkoxide, and a diffraction grating, a groove of an optical disk substrate, etc. A method for forming a fine uneven shape has been proposed.
[0068]
As the sol-gel solution, a known sol-gel solution applied as a sol-gel solution for various substrates such as a resin sheet and glass can be used. However, in the present invention, it is preferable to exhibit plasticity at least when pressing the shaping mold. If there is little time to exhibit plasticity between application and curing of the coating film and the workability of shaping is poor, for example, a resin or low molecular weight compound that increases the viscosity of the solution in order to increase plasticity. It is also preferable to appropriately add etc.
[0069]
As the organometallic compound used as the sol-gel liquid, a compound whose viscosity is increased by a polycondensation reaction or a crosslinking reaction can be used. Examples of the organometallic compound include a general formula R_nM (OR ’)_mThe metal alkoxide compound represented by these, its hydrolyzate, etc. are mentioned. In the above formula, M represents a metal such as Si, Ti, Zr, Al, Ca, Na, Pb, B, Sn, Ge, etc., and R and R ′ are a methyl group, an ethyl group, a propyl group, and a butyl group. N and m each represents an integer such that n + m is the valence of the metal M. Thus, for example, when the metal M is silicon Si, the general formula is R_nSi (OR ')_n-4It becomes.
[0070]
Further, specific examples of the metal alkoxy compound as described above include Si (OCH_Three)_Four, Si (OC₂H_Five)_FourSi-based alkoxide compounds such as Ti (OC_ThreeH₇)_Four, Ti (OC_FourH₉)_FourTitanium-based alkoxide compounds such as Zr (OC_ThreeH₇)_Four, Zr (OC_FourH₉)_FourZirconium-based alkoxide compounds such as Al (OC_ThreeH₇)_Four, Al (OC_FourH₉)_FourAluminum alkoxide compounds such as NaOC₂H_FiveAnd sodium-based alkoxide compounds.
Further, specific examples of silicon-based alkoxide compounds include methyltriethoxysilane [(CH_Three) Si (OC₂H_Five)_Three], Methyltripropoxysilane [(CH_Three) Si (OC_ThreeH₇)_Three], Dimethyldiethoxysilane [(CH_Three)₂Si (OC₂H_Five)₂] Etc. are mentioned.
[0071]
Moreover, as an organometallic compound, general formula X_nM (OR ’)_m[Wherein X is a reactive functional group such as an amino group, a carboxyl group, a glycidyl group, an acryloyloxy group, a methacryloyloxy group, etc.], for example, when the metal is silicon, a so-called silane cup A compound called a ring agent can also be used.
[0072]
Examples of the resin or low-molecular compound added to improve plasticity during shaping include acrylic resins, thermoplastic resins such as polyvinyl alcohol, and polyethers such as polyethylene glycol, polypropylene glycol, and polytetraethylene glycol. Low molecular organic compounds such as compounds can be used.
For the sol-gel solution, water or a solvent such as alcohol such as methanol or ethanol, a ketone such as methyl ethyl ketone or methyl isobutyl ketone, or an ester such as ethyl acetate or butyl acetate is appropriately used. In the sol-gel solution, an acid such as hydrochloric acid or an alkali is appropriately used as a catalyst for promoting a hydrolysis reaction such as an organometallic compound or a hydrolyzate thereof.
[0073]
[Shaping by shaping mold]
Then, if the forming mold as described above is pressed and released from the coating film formed by applying the sol-gel solution, desired fine unevenness is formed on the surface of the coating film, and a fine uneven layer is obtained. . In addition, the coating film is in a plastic state at the time of shaping, but the reaction further proceeds after shaping to completely solidify the coating film to form a fine uneven layer. In addition, you may heat suitably at the time of shaping.
[0074]
[Baking]
After releasing the shaping mold, if the base material is an inorganic base material such as glass and can withstand the firing temperature, the fine uneven layer obtained after shaping is further fired to leave the organic component remaining If so, it may be baked to form an inorganic layer. By firing, the fine uneven layer having fine unevenness on the surface is more excellent in heat resistance, weather resistance, hardness, washing resistance and the like. Therefore, for example, an antireflection article to which post-treatment requiring heat resistance such as when a transparent conductive film such as an ITO film is further formed on the fine irregularities by a physical method can be obtained. The firing temperature is usually 200 ° C. or higher, for example, 450 ° C. In addition, by passing through a baking process, even when a resin or a low molecular weight organic compound is added to the sol-gel solution so that it can be shaped easily, these organic components are burned and no organic components remain. A fine uneven layer can be formed as the inorganic layer. Therefore, it is possible to prevent performance degradation such as heat resistance, weather resistance, hardness, and washing resistance due to the remaining of these organic components.
[0075]
Even if the base material is an inorganic base material such as glass, the firing step should be omitted if the performances such as heat resistance, weather resistance, hardness, and washing resistance are excessive. You can also. If the firing step is omitted, the processing time is shortened, so that productivity is improved. Further, in the case where the substrate is an organic material and is a continuous belt-like substrate such as a resin sheet, the firing step cannot be performed, but a continuous process is possible and the production method is excellent in productivity.
[0076]
〔Base material〕
The substrate 1 is not particularly limited. Inorganic materials such as glass (including ceramics), and synthetic resins such as thermoplastic resins and thermosetting resins can be used. In addition, when baking a coating film, an inorganic material is preferable as a base material at the point of the heat resistance at the time of baking. As the material for the base material, a material corresponding to the application of the antireflection article may be used. Moreover, a transparent thing is normally used for a base material.
[0077]
In addition, as a base material of an inorganic material, glass, such as soda glass and quartz glass, ceramics, etc. are mentioned.
Moreover, as a base material of the organic material, a thermoplastic resin is representative, for example, poly (meth) methyl acrylate, poly (meth) ethyl acrylate, methyl (meth) acrylate-butyl (meth) acrylate. Acrylic resin such as a copolymer [However, (meth) acryl means acryl or methacryl. ], Polycarbonate resin, polypropylene, polymethylpentene, cyclic olefin polymer (typically norbornene resin, etc., for example, product name “ZEONOR” manufactured by ZEON CORPORATION, “ARTON” manufactured by JSR Corporation Etc.), thermoplastic polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyamide resin, polystyrene, acrylonitrile-styrene copolymer, polyether sulfone, polysulfone, cellulose resin, vinyl chloride resin , Polyether ether ketone, polyurethane and the like.
[0078]
[Use of anti-reflective articles]
In addition, as an anti-reflective article by this invention, a shape is arbitrary, such as a three-dimensional shape, a board, a sheet | seat, and a use is not specifically limited. However, since the fine unevenness of the antireflection surface is extremely fine, there is no need to pay attention to dirt and scratches. Therefore, the fine unevenness is preferably not exposed on the outer surface but provided on the inner surface. Applications or applications provided in the apparatus are suitable. In addition, the use which this invention can apply is not limited to the use illustrated from now on.
[0079]
For example, it is a window material for an information display unit in various devices such as a mobile phone and a digital camera. In these display units, a resin or glass window material that is a plate or a molded product is disposed on the front surface of a display panel such as an LCD. The anti-reflective article as a window material is not provided with the fine unevenness peculiar to the present invention in terms of resistance to scratches and dirt because the outside is exposed, and the fine unevenness is provided on the inner back side. Is preferred. In addition to the display panel such as an LCD, the information display unit may be displayed by a mechanical means such as a mechanical analog meter represented by a watch, or may be a window material of these.
The window material may have a flat plate shape, but may have a protrusion or the like around it from the viewpoint of assembly or design.
[0080]
In addition, as a device having the information display unit with a window as described above, in addition to a mobile phone and a watch, a personal computer, a PDA such as an electronic notebook, a portable information terminal, a calculator, a CD player, a DVD player, Various portable music players such as MD players and semiconductor memory music players, video tape recorders, IC recorders, video cameras, digital cameras, label printers and other electronic devices, or electric rice cookers, electronic pots, washing machines, etc. There are electrical products.
[0081]
In the case of a plate-like or sheet-like antireflection article, a transparent substrate such as a transparent plate used for a transparent touch panel or the like can be used. The transparent touch panel adds an input function to the display unit. However, because the product is assembled as a separate part from the display panel such as LCD and CRT, a gap remains between the display panel and the transparent touch panel, and light reflection does not occur. Arise. Then, if the transparent base material which comprises the back surface side of a transparent touch panel is made into the antireflection article which provided the fine unevenness | corrugation peculiar to this invention on the back surface, light reflection can be prevented.
[0082]
The transparent touch panel is, for example, a PDA such as an electronic notebook or a portable information terminal (equipment), a car navigation system, a POS (point-of-sale information management) terminal, a portable order entry terminal, an ATM (automatic cash deposit payment combined use) Machine), facsimile, landline telephone, mobile phone, digital camera, video camera, personal computer, PC display, television receiver, TV monitor display, ticket vending machine, measuring instrument, calculator, electronic musical instrument, etc., photocopying Used in office machines such as machines, ECR (cash registering machines), or electrical products such as washing machines and microwave ovens.
The antireflection article of the present invention can also be used as various optical components. For example, a camera lens, a finder window material of a camera, a spectacle lens, a Fresnel lens of an overhead projector, an output extraction window of a laser device, an optical input window of an optical sensor, a telescope lens, and the like.
[0083]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
[0084]
[Example 1]
A transparent reflection having a configuration in which a shaping mold and a sol-gel solution are prepared as follows, and a fine uneven layer 3 having fine unevenness 2 on the surface as shown in FIG. Prevention article 10 was produced.
[0085]
(1) Fabrication of shaping mold: After a metal chromium film was formed on one side of a quartz glass substrate, a positive resist was spin-coated thereon to form a resist film. Next, after drawing mesh-like drawing data having a vertical and horizontal period of 300 nm on the resist film with an electron beam drawing apparatus, the resist film was developed with a developer to form a resist pattern layer having the mesh opening region opened. Next, the metal chromium film exposed from the opening of the resist pattern layer was dry etched with a chlorine-based gas. Then, the resist pattern layer and the metal chromium film were used as an etching resistant layer, and the glass substrate was dry-etched with a fluorine-based gas to produce a prototype (mother plate) in which a desired fine uneven shape was formed. Next, a replica mold (nickel stamper) made of a nickel-plated plate having a thickness of 80 μm was produced as a shaping mold from this prototype by electroplating.
[0086]
(2) Preparation of sol-gel solution: As sol-gel solution, high molecular weight SiO₂Sol solution and low molecular weight SiO₂Each was prepared with a sol solution and mixed.
[0087]
(2-1) High molecular weight SiO₂Preparation of sol solution: 22.7 g (0.17 mol) of methyltrimethoxysilane (MTMOS) and 14 ml of methanol were added to a four-necked flask equipped with a stirrer, a nitrogen inlet tube, and a discharge tube, and mixed to 0 ° C. Cooled down. This, water and hydrochloric acid, respectively, H₂After adding O / MTMOS = 1.30 and HCl / MTMOS = 0.105 and stirring at room temperature for 10 minutes, the mixture was stirred at 70 ° C. for 3 hours at 150 rpm while introducing dry nitrogen. The solvent was distilled off under reduced pressure to obtain a high molecular weight product composed of a highly viscous polymer.
This high molecular weight substance is MeSiO_1.5(However, Me is a methyl group) The high molecular weight substance is dissolved in methyl ethyl ketone so that the solid content concentration is 1.5% by mass when it is assumed to be hydrolyzed and condensed to a high molecular weight SiO.₂A sol solution was obtained.
The molecular weight of this high molecular weight product was 42000 in terms of weight average molecular weight as measured by GPC (gel permeation chromatography) using polystyrene as a standard sample.
[0088]
(2-2) Preparation of low molecular weight SiO2 sol solution: Methyltriethoxysilane (MTEOS) is ideally SiO₂Or MeSiO_1.5MTEOS was dissolved in methyl ethyl ketone as a solvent so that the solid content concentration was 3% by weight when it was assumed that the product was hydrolyzed and condensed, and stirred for 30 minutes until the liquid temperature was stabilized at 25 ° C. Next, hydrochloric acid having a concentration of 0.005 N as a catalyst was added in an equimolar amount with the alkoxy group of MTEOS, and a hydrolysis reaction was performed at 25 ° C. for 3 hours. Next, what mixed sodium acetate and acetic acid as a hardening | curing agent was added, and it stirred at 25 degreeC for 1 hour, and obtained the low molecular-weight SiO2 sol solution.
[0089]
(3) Preparation of sol-gel solution: low molecular weight SiO₂In the sol solution, the high molecular weight SiO₂30% by mass of the sol solution was added to obtain a sol-gel solution for coating.
[0090]
(4) Formation and shaping of coating film: The above sol-gel solution was applied to the surface of a base material made of a polyethylene terephthalate sheet having a thickness of 250 μm so that the film thickness after removal of the solvent would be 10 microns, at 60 ° C. The coating film was dried for 5 minutes. Next, using the shaping mold (1), desired fine irregularities were shaped on the surface of the coating film by a hot press method. That is, SiO₂Apply the shaping mold to the substrate on which the layer is applied [120 ° C., 1 Pa (10 kgf / cm²)]. As a result, on the surface of the coating film on the substrate obtained by peeling off the shaping mold, a reverse uneven pattern of the shaping mold is formed, resulting in a fine irregularity layer having desired fine irregularities on the surface. A transparent antireflective article having a structure in which the layer was laminated on the substrate was obtained.
[0091]
When the reflectance of the antireflection article having the fine uneven layer on the substrate surface was measured, the luminous reflectance was 0.3%, and the antireflection effect was recognized.
[0092]
[Example 2]
A transparent reflection having a configuration in which a shaping mold and a sol-gel solution are prepared as follows, and a fine uneven layer 3 having fine unevenness 2 on the surface as shown in FIG. Prevention article 10 was produced.
[0093]
(1) Fabrication of shaping mold: After a metal chromium film was formed on one side of a quartz glass substrate, a positive resist was spin-coated thereon to form a resist film. Next, after drawing mesh-like drawing data having a vertical and horizontal period of 300 nm on the resist film with an electron beam drawing apparatus, the resist film was developed with a developer to form a resist pattern layer having the mesh opening region opened. Next, the metal chromium film exposed from the opening of the resist pattern layer was dry etched with a chlorine-based gas. Then, the resist pattern layer and the metal chromium film were used as an etching resistant layer, and the glass substrate was dry-etched with a fluorine-based gas to produce a prototype (mother plate) in which a desired fine uneven shape was formed. Next, a replica mold (nickel stamper) made of a nickel-plated plate having a thickness of 80 μm was produced as a shaping mold from this prototype by electroplating.
[0094]
(2) Preparation of sol-gel solution: As sol-gel solution, high molecular weight SiO₂Sol solution and low molecular weight SiO₂Each was prepared with a sol solution and mixed.
[0095]
(2-1) High molecular weight SiO₂Preparation of sol solution: 22.7 g (0.17 mol) of methyltrimethoxysilane (MTMOS) and 14 ml of methanol were added to a four-necked flask equipped with a stirrer, a nitrogen introduction tube, and a discharge tube solution, and mixed at 0 ° C. Cooled to. This, water and hydrochloric acid, respectively, H₂After adding O / MTMOS = 1.30 and HCl / MTMOS = 0.105 and stirring at room temperature for 10 minutes, the mixture was stirred at 70 ° C. for 3 hours at 150 rpm while introducing dry nitrogen. The solvent was distilled off under reduced pressure to obtain a high molecular weight product composed of a highly viscous polymer.
This high molecular weight substance is MeSiO_1.5The high molecular weight material was dissolved in methyl ethyl ketone so that the solid content concentration was 1.5% by mass when it was assumed that the product was hydrolyzed and condensed to high molecular weight SiO.₂A sol solution was obtained.
The molecular weight of this high molecular weight product was 42000 in terms of weight average molecular weight as measured by GPC (gel permeation chromatography) using polystyrene as a standard sample.
[0096]
(2-2) Preparation of low molecular weight SiO2 sol solution: Methyltriethoxysilane (MTEOS) is ideally SiO₂Or MeSiO_1.5(However, Me is a methyl group) MTEOS is dissolved in methyl ethyl ketone, which is a solvent, so that the solid content concentration becomes 3% by weight when it is assumed that hydrolysis and condensation have occurred, and the liquid temperature is stabilized at 25 ° C. Stir for 30 minutes. Next, 0.005N hydrochloric acid as a catalyst was added in an equimolar amount with the alkoxy group of MTEOS, and a hydrolysis reaction was performed at 25 ° C. for 3 hours. Next, what mixed sodium acetate and acetic acid as a hardening | curing agent was added, and it stirred at 25 degreeC for 1 hour, and obtained the low molecular-weight SiO2 sol solution.
[0097]
(3) Preparation of sol-gel solution: low molecular weight SiO₂In the sol solution, the high molecular weight SiO₂A sol-gel solution for coating was obtained by adding 30% by mass of the sol solution and further adding 5% by mass of polyethylene glycol to the solution after the addition.
[0098]
(4) Formation and shaping of coating film: The above sol-gel solution was applied to the surface of a glass substrate having a thickness of 2 mm so that the film thickness after removal of the solvent would be 10 microns, and at 60 ° C. for 5 minutes. It dried and it was set as the coating film. Next, using the shaping mold (1), desired fine irregularities were shaped on the surface of the coating film by a hot press method. That is, SiO₂Apply the shaping mold to the substrate on which the layer is applied [120 ° C., 1 Pa (10 kgf / cm²)]. As a result, the reverse uneven pattern of the shaping mold was formed on the surface of the coating film on the substrate obtained by peeling the shaping mold, and a fine uneven layer having desired fine unevenness on the surface was obtained. Further, after peeling the shaping mold, the fine uneven layer was baked at 450 ° C. for 30 minutes to obtain a desired antireflection article as a final fine uneven layer.
[0099]
When the reflectance of the antireflection article having the fine uneven layer on the substrate surface was measured, the luminous reflectance was 0.5%, and an antireflection effect was recognized.
[0100]
【The invention's effect】
(1) According to the method for producing an antireflective article of the present invention, the fine irregularities on the surface of the antireflective article are once shaped in comparison with the case of directly shaping each product by photoresist coating, exposure, development, etc. Since it can be formed by shaping from this shaping mold, the productivity is good. In addition, since the fine uneven layer formed on the surface is formed by a sol-gel method, an inorganic layer is obtained, which is superior in heat resistance, weather resistance, etc. compared to the case where it is formed as a resin layer by the 2P method or the like, for example. You can do it. Further, the hardness of the fine irregularities can be obtained, and the washing resistance and the like are improved. In addition, when the fine uneven layer after shaping is not fired, the substrate can be an organic material having poor heat resistance such as a resin other than an inorganic material such as glass. In addition, the productivity is good because there is no time-consuming baking step, and it is possible to further improve the productivity by continuous treatment for a continuous belt-like substrate such as a resin sheet.
Further, the antireflection function imparted to the antireflection article by the production method of the present invention does not reduce light reflection by specular irregular reflection such as satin treatment, but a rapid refractive index at the interface between the article surface and air. Since this is realized by relaxing the change, the light transmittance is improved as much as the light reflectance is reduced. Therefore, when used for a window material of an information display section such as a display, an antireflection article that improves the visibility of display and increases the use efficiency of display light can be obtained.
[0101]
(2) If the substrate is an inorganic substrate and the fine uneven layer is baked, even if the fine uneven layer contains an organic component, the organic component is burned and disappeared to form an inorganic layer. The heat resistance, weather resistance, hardness, washing resistance and the like can be more reliably improved. Therefore, for example, post-processing that requires heat resistance such as when a transparent conductive film such as an ITO film is further formed on the fine irregularities by a physical method can be easily performed.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an explanatory view conceptually explaining in one form the manufacturing method of an antireflection article of the present invention.
FIG. 2 is a diagram (part 1) for conceptually explaining the distribution of effective refractive index obtained by fine unevenness.
FIG. 3 is a diagram (part 2) for conceptually explaining an effective refractive index distribution obtained by fine unevenness.
FIG. 4 is a diagram (part 3) for conceptually explaining the distribution of effective refractive index obtained by fine unevenness.
FIG. 5 is a cross-sectional view illustrating some of (vertical) cross-sectional shapes of fine irregularities.
FIG. 6 is a cross-sectional view illustrating some of arrangements of fine irregularities in a horizontal plane.
[Explanation of symbols]
1 Base material
2 Fine irregularities
2A Fine irregularities (on the shaping mold)
2t The most convex part (of fine unevenness 2)
3A Coating film (before shaping)
3 Fine uneven layer
10 Anti-reflective articles
40 prototype
41 Molding type (replication type)
n Refractive index
n_a  Refractive index (air)
n_b  Refractive index (base material)
n₀  Refractive index
n₁  Refractive index
n_ef(Z) Effective refractive index
H_MIN  Minimum height (of fine irregularities)
P_MAX  period
R reflectance
λ_MIN  Minimum wavelength
λ_MAX  Maximum wavelength

Claims (2)

A method for producing an antireflective article comprising a fine uneven layer having antireflective fine unevenness on a surface formed on a substrate,
When the minimum wavelength in the visible light wavelength band is λ _MIN , and the period at the most convex portion of the fine unevenness is P _MAX ,
P _MAX ≦ λ _MIN
Have the relationship
And the cross-sectional area occupation rate of the material part of the base material in the cross section when it is assumed that the fine unevenness is cut by a plane orthogonal to the unevenness direction, goes from the most convex portion of the fine unevenness to the most concave portion. It is unevenness that gradually increases gradually,
Sequentially as a process when manufacturing the antireflection article,
(A) First, prepare a prototype modeled with fine irregularities,
(B) Next, the above-mentioned prototype is used as a shaping mold, or a replica mold is produced by replicating the fine irregularities on the surface of the prototype one or more times by mold taking and reversal. Using the sol-gel liquid coating film containing the organometallic compound formed on the base material, after pressing the shaping mold, the mold is released to form fine irregularities on the surface of the coating film. A method for producing an antireflection article by a sol-gel method, wherein each step is performed to form a fine uneven layer.   The method for producing an antireflective article by the sol-gel method according to claim 1, wherein the base material is an inorganic base material, and the fine uneven layer having fine unevenness formed on the surface is fired after releasing the shaping mold.

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