JP2004211021A - Molding resin composition and optical element produced by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding resin composition which can be molded to provide a molded product with little heat shrinkage and high scale accuracy, and can provide the surface of the molded product with a dielectric multilayer membrane having high heat resistance, desired performance and durability; and an optical element which is formed to have a minutely uneven construction and a surface provided with a reflection preventing layer by the dielectric multilayer membrane. <P>SOLUTION: The molding resin composition comprises (A) a fluorinated epoxy, (B) a non-fluorinated epoxy, and (C) a silane coupling agent at their respective wt.% contents of w<SB>A</SB>, w<SB>B</SB>, and w<SB>C</SB>, wherein a coordinates (w<SB>A</SB>, w<SB>B</SB>, and w<SB>C</SB>) is preferably within the quadrilateral DEFG, more preferably the quadrilateral DHIG, and most preferably the quadrilateral KLMN in a regular triangle ABC where the compounds (A), (B), and (C) have their respective contents of 100 wt.% to indicate that they stand at their respective apexes of A, B, and C. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

ここでＲはＣＨ_２（ＣＦ_２）_ｎＣＨ_２（ｎは正の整数）であるが、ｎは１〜４が好ましい。
【００１３】
化合物（Ｂ）は非フッ素化エポキシ化合物であり、脂環エポキシ化合物であるのが好ましい。化合物（Ｃ）はシランカップリング剤である。とくにエポキシ基を含有するのが好ましく、なかでもγエポキシ基またはシクロへキシル基を含有するのが望ましい。
【００１４】
上記の樹脂組成物は耐熱性が高く、基板温度を２５０℃程度まで上昇させて誘電体多層膜を形成することができ、緻密で耐候性の高い膜形成が可能である。これにより高い性能を有する反射防止層を形成した光学素子を提供することが可能となる。
【００１５】
また、硬化後の樹脂組成物は透明であり、上記組成範囲を選ぶことにより、その屈折率は石英ガラスの屈折率１．４６にほぼ一致する。したがって基材を石英ガラスとした場合には、固体組成物層−基材界面での反射を低減することができる。またはこの樹脂組成物からなる光学素子と光ファイバとを光学的に結合させる場合には、光ファイバ端面と樹脂組成物表面の界面での反射を抑制することができる。
【００１６】
なお、成形用樹脂組成物は、同組成物を硬化させるための重合開始剤を０．１〜７重量％含有することが望ましい。また、劣化防止のため酸化防止剤を５重量％以下含有することが望ましく、２重量％以下であればより望ましい。
【００１７】
以上の組成を有する組成物を使用し、所望の形状を有する成形型によって成形し、熱および紫外線の少なくとも一方を付与して重合硬化させて固体組成物層を得る場合、成形の際の熱収縮が小さいので、成形型との寸法差が小さい成形体を形成できる。また酸化防止剤の作用により、成形物の長期的な劣化を防止することができる。
【００１８】
また、本発明の成形用樹脂組成物を硬化した固体組成物層の屈折率は１．４５〜１．４８の範囲とする。上述のように、屈折率が１．４６の石英ガラスを基材として用いた場合、固体組成物層の屈折率は上記成分（Ａ）、（Ｂ）、（Ｃ）の調合比率を調整することで所定の範囲内で基材の屈折率にほぼ一致する値に選ぶことができ、固体組成物層−基材界面での反射を抑制することができる。
【００１９】
本発明の光学素子は、上記の成形用樹脂組成物を、基材と成形型との間に充填押圧した後、熱および紫外線の少なくとも一方を付与して重合硬化させて所定の形状を有する固体組成物層を形成した後、その表面に誘電体膜を少なくとも２層積層する。
この誘電体多層膜は反射防止膜として作用し、上記固体組成物層表面に光を入射させ、基材側に透過させて使用する光学素子において、入射光の反射を抑制することができる。
【００２０】
また、光学素子の基材を石英ガラスとすることが好ましい。本発明の成型用樹脂組成物は硬化後の屈折率を石英ガラスのそれにほぼ一致させることができるため、固体組成物層と基材の界面での反射を抑えることができる。
【００２１】
本発明の光学素子は、表面形状を選択することによって透過型回折格子、フレネルレンズまたは微小レンズアレイの機能を付与することができる。
【００２２】
成形技術を使用するため、これらの光学素子を大量にかつ安価に提供できる。また本発明の成形用樹脂組成物は成形時の収縮が小さいため、所望の設計形状を正確に作り込んだ成形型の形状を正確に転写できる。また、これらの光学素子はいずれも所定の表面形状を有する固体組成物層の表面に光を入射させ、基材側へ透過させて使用されるが、表面に誘電体多層膜による反射防止膜を設け、また固体組成物層と基材の屈折率を整合させることが可能なため、反射損失の少ない光学素子を実現できる。
【００２３】
【発明の実施の形態】
以下、この発明の実施形態について詳細に説明する。
本発明においては、流動性を有する化合物を重合硬化させて固体組成物を形成する。所定の表面凹凸形状を形成するため、上記化合物を基材と成形型との間に密着させて膜状に挟持し、ついで熱および紫外線の一方あるいは両方を付与し、そのエネルギーによってこれを重合硬化させる。硬化した組成物を成形型から離型し、その後に必要に応じて加熱することにより、成形型の表面形状を反転させた形状が上記組成物表面に転写される。
【００２４】
上記のように重合硬化を起こすために、この化合物はその分子内に少なくとも１つの重合性有機基を有していることが必要である。光重合は、重合開始剤の光分解によって生成したラジカルまたはカチオンの重合性有機基への付加重合によって引き起こされる。そのため脱水縮合反応に比べ収縮が小さく、化学的に結合した均一な膜を瞬時に形成させることができる。熱重合の場合は、重合開始剤の熱分解による。よって重合性有機基は、光あるいは熱で重合する有機基を用いる。
【００２５】
光重合性有機基としては、エポキシ基、アクリロキシ基、メタクリロキシ基、ビニル基、およびこれらを含有する有機基を例示することができる。また熱重合性有機基としては、エポキシ基、ビニル基、およびこれらを含有する有機基を例示することができる。
【００２６】
エポキシ基を有する液状の重合性化合物としては、フッ素化エポキシ化合物、あるいは脂環式エポキシ化合物、芳香族エポキシ化合物などの非フッ素化エポキシ化合物が例示できる。本発明においては以下に示すようにフッ素化エポキシ化合物と非フッ素化エポキシ化合物を混合して使用する。
【００２７】
本発明においては、フッ素化エポキシ化合物としては前掲の一般式（化２）で示される化合物を使用する。
また、フッ素化エポキシ化合物と混合して使用される脂環族エポキシ樹脂の例として以下の構造式で表される化合物が挙げられる。
【００２８】
３，４−エポキシシクロヘキシルメチル（３，４−エポキシシクロヘキサン）カルボキシレート（化３）、
【化３】

ビニルシクロヘキセンジエポキシド（化４）、
【化４】

３，４−エポキシ−６−メチルシクロヘキシルメチル−３，４−エポキシ−６−メチルシクロヘキサンカルボキシレート（化５）、
【化５】

ビス（３，４−エポキシ−６−メチルシクロヘキシルメチル）アジペート（化６）、
【化６】

ジシクロペンタジエンオキシド（化７）、
【化７】

ビス（２，３−エポキシシクロペンチル）エーテル、リモネンジオキシド（化８）
【化８】

が、耐熱性、耐薬品性、液の粘度の点で取り扱いが容易なこと、硬化性、また原料の入手のし易さの観点から好ましく用いられる。
【００２９】
その他、一群の化学式（化９）で示される化合物も使用できる。
【化９】

芳香族エポキシ化合物としては、一般式（化１０）
【化１０】

におけるＸがつぎの化学式（化１１〜化１４）で表される化合物を例示できる。これらの中でも、ビスフェノールＡ型（化１１）、
【化１１】

ビフェニル型（化１２）、
【化１２】

ビスフェノールＦ型（化１３）、
【化１３】

ジフェニルエーテル型（化１４）、
【化１４】

ビスフェノールＳ型（化１５）、
【化１５】

その他の化合物（化１６）
【化１６】

などが、耐熱性、耐薬品性、液の粘度の観点で取り扱いが容易性、硬化性、また原料の入手のし易さの観点から好ましく用いられる。
【００３０】
また、基材との密着性、耐湿性を向上させるため、シランカップリング剤を添加してもよい。シランカップリング剤としては、３−グリシドキシプロピルトリメトキシシラン（化１７）、
【化１７】

３−グリシドキシプロピルトリエトキシシラン（化１８）、
【化１８】

あるいは、２−（３，４−エポキシシクロヘキシルエチルトリメトキシシラン、２−（３，４−エポキシシクロヘキシルエチルトリエトキシシラン（以上、化１９）を用いることができる。
【化１９】

【００３１】
成形用組成物に含有される重合性有機基が光重合性である場合には、光重合開始剤を添加する。ラジカル光重合開始剤としては、［２−ヒドロキシ−２−メチル−１−フェニルプロパン−１−オン］（Ｓ１と略称する。以下同様）、［１−（４−イソプロピルフェニル）−２−ヒドロキシ−２−メチルプロパン−１−オン］（Ｓ２）、［４−（２−ヒドロキシエトキシ）フェニル−（２−ヒドロキシ−２−プロピルケトン］（Ｓ３）、［２，２−ジメトキシ−１，２−ジフェニルエタン−１−オン］（Ｓ４）、［１−ヒドロキシ−シクロヘキシル−フェニル−ケトン］（Ｓ５）、［２−メチル−１［４−（メチルチオ）フェニル］−２−モルフォリノプロパン−１−オン］（Ｓ６）、［ビス（２，６−ジメトキシベンゾイル）−２，４，４−トリメチル−ペンチルフォスフィンオキサイド］（Ｓ７）、［２−ベンジル−２−ジメチルアミノ−１−１−（４−モルフォリノフェニル）−ブタノン−１］（Ｓ８）を例示することができる。
【００３２】
また、カチオン光重合開始剤としては、フェニル−［ｍ−（２−ヒドロキシテトラデシクロ）フェニル］ヨードニウムヘキサフルオロアンチモネート（Ｓ９）、ジフェニルヨードニウムテトラキス（ペンタフルオロフェニル）ボレート（Ｓ１０）等が例示できる。光重合開始剤の量は、液組成物の全重量に対して、０．１〜７重量％が好ましい。
【００３３】
加えて酸化防止剤として燐酸系の化合物を添加しても良い。９，１０−ジヒドロ−９−オキサ−１０−フォスファフェナンスレン−１０−オキサイドが例示できる。主成分に対して５％以下、より好ましくは２％以下含有することが好ましい。
【００３４】
本発明の光学素子の所定表面形状は成形によって形成するため、上記重合性有機基を含む化合物は流動性を有する必要があり、その粘度は３〜２５００ｍＰａ・ｍの範囲に調整するのが好ましく、１００〜１５００ｍＰａ・ｍがより好ましく、１００〜１０００ｍＰａ・ｍが最も好ましい。
【００３５】
所定表面形状を有する光学素子を成形するプロセスとしては、代表的に下記２つの方法を挙げることができる。
第１の方法（以下型注ぎ法という）では、成形型に成形用組成物を注ぎ脱気する。つぎに成形型と基材とを接合し、加熱または紫外線照射を行う。これによって組成物は硬化する。硬化した基材上の組成物を成形型から離型し、その後に必要に応じて加熱する。
【００３６】
以上の方法を図１により詳細に説明する。表面に所定の微小な凹凸形状を有する成形型１０を型面を上に向けて水平に保ち、粘度が１００〜１０００ｍＰａ・ｍの成形用組成物３０をその成形型１０の上に注いで成形型の窪みを埋め尽くすように満たす（図１（ａ））。なお、注ぐ代わりに、その成形型を成形用組成物の浴に浸漬したり、刷毛で成形型表面に塗布する等の方法でもよい。
【００３７】
その状態で、成形型１０上に満たされた組成物３０が空気を含まないように、室温から１００℃程度の温度で、２〜５Ｐａに減圧した状態で５〜１０分間保持し、液中の泡や溶解酸素を脱気しても良い。
ついで基材２０を組成物３０と基材表面との間に空隙を生じないように成形型１０上の組成物３０に接触させ、組成物３０を基材２０と成形型１０との間で層状になるように挟持する（図１（ｂ））。その状態で紫外線を照射しながら２０〜１００℃で１〜３０分間保持するか、または１４０〜１８０℃に加熱して１０〜１２０分間保持して、組成物を重合硬化させる。
【００３８】
紫外線を照射する場合には、基材２０および成形型１０の少なくとも一方が紫外線を透過することができる材質からなるものを使用する。つぎに、成形型１０を引き剥がして離型することにより、成形型１０の表面凹凸形状を反転させた凹凸形状を表面に有する高いガラス転移温度をもつ固体組成物層３２が基体２０の表面に接合された状態で形成される（図１（ｃ））。
【００３９】
ついで必要に応じて、これを最終的に、常圧または２〜５Ｐａの減圧下で、１００〜２００℃で１５〜２５０分間加熱することにより、固体組成物層に残留する重合開始剤、未重合物を気化させる。これにより固体組成物層は厚み方向にわずかに体積収縮して緻密な膜となる。このようにして形成した所定表面形状を有する固体組成物層３２上に、図１（ｄ）に示すように誘電体多層膜４０を被覆することにより、本発明の光学素子１００が得られる。
【００４０】
第２の成形方法（以下、基材注ぎ法という）は成形用組成物を基材表面に直接注ぎ、脱気した後、成形型を基材表面の組成物に押し当て、そのままの状態で紫外線照射あるいは加熱し、転写成形する。その後、成形型を離型し、必要に応じて最終加熱を実施する方法である。
【００４１】
以上の方法は第１の方法と図１の（ｂ）以降は同様である。基材の被覆すべき表面を水平に保ち、粘度が１００〜１０００ｍＰａ・ｍの組成物をその基材の上に注いで所定の厚みになるように層状に広げる。その状態で、組成物が空気を含まないように、室温〜１００℃で、２〜５Ｐａに減圧しながら５〜１０分間保持して、液中の泡や溶解酸素を脱気してもよい。
【００４２】
ついで表面に所定の微小凹凸形状を有する成形型を層状の組成物の上に押し当てて圧力０．５〜１２０ｋｇ／ｃｍ^２、温度２０℃〜１５０℃で６０秒〜６０分間保持するか、または上記圧力で押し当て、その状態で紫外線を被照射位置での照射強度が１．０〜１２０ｍＷ／ｃｍ^２になるように照射しながら、温度２０〜１００℃で６０秒〜３０分間保持して、成形用組成物の重合反応をほぼ完了させて硬化させる。
【００４３】
紫外線を照射する場合には、基材および成形型の少なくとも一方が紫外線を透過することができる材質からなるものを使用する。そして成形型を引き剥がして離型することにより、成形型の凹凸形状を反転させた凹凸形状を表面に有する固体組成物層が基材の表面に接合された状態で形成される。
【００４４】
ついで必要に応じてこれを例えば、常圧または２〜５Ｐａの減圧下で、１８０〜２５０℃で１５〜３５０分間加熱することにより、層内に残留する光重合開始剤、未重合物を気化させる。これにより固体組成物層は厚み方向にわずかに体積収縮して緻密な膜となる。
【００４５】
このようにして形成した所定表面形状を有する固体組成物層上に、誘電体多層膜を被覆することにより、本発明の光学素子が得られる。
【００４６】
本発明において用いられる成形型の最表面にはフッ素樹脂、あるいは金（Ａｕ）からなる離型膜を設けることが好ましい。フッ素樹脂は、スピンまたはディップ法により、成型型に均一に成膜される。また金は、成型材料に対する良好な離型性、押圧に耐えうる機械的強度、耐熱性、耐腐食性、および耐酸化性を有するので離型膜として優れた材料である。
【００４７】
このような離型膜の厚みは２００〜１０００ｎｍであることが好ましく、より好ましくは４００〜６００ｎｍである。離型膜は、表面が平滑であるほど離型性が高いことから、スパッタ法、真空蒸着法、無電解メッキ法、電解メッキ法、箔張り付け法などにより均一、かつ、平滑に成膜されていることが好ましい。
【００４８】
上記型芯材の材質としては離型膜に近似した膨張係数を有するものを選ぶことが好ましい。樹脂からなる型芯材は、微細な加工が容易にでき、所望の形状に容易に成形しやすいという利点があり、ガラスまたは金属の型芯材は耐熱性および機械的強度が高く、耐久性に優れている。
【００４９】
本発明における成形型はその表面に凹部または凸部が設けられている。凹凸部としては、例えば球状、円錐状、角錐状や断面任意形状のスリット状等を例示できる。そして、球状、円錐状、角錐状は離型膜の全域あるいは部分的に任意数設けられる。一方、凹部としてスリットを設ける場合、スリットは直線状、曲線状に任意条設けてもよく、複数条設ける場合には同心円状、格子状に設けてもよい。
【００５０】
このようにして、本発明によれば、１００℃以上のガラス転移温度を有し、最大厚み（表面の凹凸の凸部で測った膜厚）が１μｍ〜１ｍｍ、好ましくは２０〜１５０μｍで、微細な凹凸形状、例えば、１μｍ〜５００μｍの範囲内の所定値の幅（凹凸ピッチ）および５〜５００μｍの範囲内の所定値の高さを有する表面凹凸が形成された膜が平坦板状または曲面板状の基材上に形成される。
【００５１】
この膜は弾力性に富み（脆性が少なく）、膜の強度が高く膜に亀裂が発生し難い。そして膜の内部には成型時の発泡は認められず、また成型時の膜の収縮が小さいため、膜表面の微細凹凸形状の寸法精度が極めて高い優れた転写性が実現できる。具体的には、例えば高さが２０〜１００μｍの凸部を多数形成する場合、膜表面凸部の高さのばらつきは１μｍ以下である。また膜表面の凸部間隔の成形型からのズレは測定精度（０．２μｍ）以下である。
【００５２】
この発明に用いる基材としては、平板状、曲板状などの形状のものが用いられる。基材として２００℃と２０℃における基材表面の反り量（基材の表面方向の単位長さあたりのその表面に垂直な方向の熱変形長さ）が１ｃｍあたり±５μｍ以内であることが望ましい。反り量がこの範囲を越えると膜の成形過程において基材と膜が界面で剥離もしくは膜に亀裂を生じるおそれがあるので、基材の材料、寸法、形状を選ぶことが好ましい。
【００５３】
また、この基材は１．５×１０^−５℃^−１以下の線膨張率を有することが好ましい。基材の線膨張率が１．５５×１０^−５℃^−１を超えると、例えばポリプロピレン（９〜１５×１０^−５℃^−１）のような大きい熱膨張係数を有するプラスチックス基材の場合、組成物の成形過程において基材と膜が界面で剥離したり、膜に亀裂を生じるからである。
【００５４】
通常の無機ガラスは１．５×１０^−５℃^−１以下の線膨張率を有する。また基材の少なくとも表面は酸化物であることが好ましい。もし組成物と接する基材表面が酸化物でない場合、膜の成形過程において付着強度が下がり、場合によっては基材と膜が界面で剥離を生じるからである。
【００５５】
好ましい基材の材質の例として、石英ガラスをはじめとする珪酸塩系ガラス、ホウ酸塩系ガラス、リン酸塩系ガラス等の酸化物ガラス、石英、セラミックス、シリコン、アルミニウムその他の金属、エポキシ樹脂、ガラス繊維強化ポリスチレンなどを挙げることができる。金属はそのままではオルガノポリシロキサン膜が接合しないが、予め金属の表面を酸化剤で処理しておけば基材として使用することができる。
【００５６】
また本発明における基材として、光学素子が使用する波長の光、例えば可視域、紫外域、または赤外域の光に対して透明な物質を用いれば、本発明による光学素子は、レンズアレイ、回折格子（例えばエシェレット回折格子、エシェロン回折格子、エシェル回折格子など）、フレネルレンズなどの透過型光学素子として機能を発揮することができる。
本発明による所定表面形状を有する光学素子製造の各工程についてさらに具体的に説明する。
【００５７】
［成形型または基材への溶液の塗布］
光または熱硬化性で流動性を有する成形用組成物を、型注ぎ法では、透明な成形型の表面に注いで５０μｍ〜１ｍｍの厚みの層（粘度：２００ｍＰａ・ｍ）を得た。基材注ぎ法でも同様である。
【００５８】
［接合・照射処理・離型］
型注ぎ法の場合には、上記組成物の上に基材の表面を接触させた後、型と基材との間で組成物を加圧展開させ、その状態で０．５〜３０分間紫外線を照射して基材と接合させる。そして組成物が完全に硬化した後、成形型を基材から引き離して離型する。
基材注ぎ法の場合には、上記塗布膜に透明な成形型を押し当て、同様に０．５〜３０分間紫外線を照射して基材と接合させ、その後、離型する。
上記いずれの方法によっても、成形型の形状を転写した微細凹凸形状を有する固体状の組成物層が基材表面に付着した状態で得られた。
【００５９】
［最終加熱］
離型して得られた固体組成物層の緻密さを向上させるための加熱条件は、１５０℃で６０分間とした。
【００６０】
［誘電体多層膜の成膜］
本発明において用いる誘電体多層膜の主要な目的は、光学素子表面からの反射防止である。要求される反射防止特性を実現するため、ＴｉＯ_２／ＳｉＯ_２、Ｔａ_２Ｏ_５／ＳｉＯ_２、ＺｒＯ_２／ＳｉＯ_２、およびＴｉＯ_２／ＭｇＦ_２等の２層膜あるいはそれ以上の多層膜を用い、使用波長、戻り光反射減衰量等の要求仕様により各層の膜厚や材料を設計する。単層の膜厚は、通常１〜６００ｎｍであることが望ましく、より好ましくは１０〜４００ｎｍである。
【００６１】
膜が緻密である程、耐久性が高いことから、スパッタ法、真空蒸着法、などにより均一、かつ、緻密に成膜することが好ましい。その上で、耐湿性の観点から、誘電体多層膜の成膜温度は５０〜２５０℃とするのが望ましく、より望ましくは８０℃〜２５０℃である。
【００６２】
なお、固体組成物層表面に形成した形状の保護およびその上層に形成する反射防止膜との密着性を強化するため、固体組成物層表面と誘電体多層膜の間にＳｉＯ_２層を設けるのが望ましい。材料はＳｉＯ_２以外を選ぶこともできる。その膜厚は、１〜３００ｎｍであることが好ましく、より好ましくは１０〜１５０ｎｍである。
【００６３】
［凸部高さのばらつき測定］
最外層の凸部高さのばらつき測定は、レーザ顕微鏡による高さ測定により実施した。
【００６４】
［耐熱性および耐湿性、光学特性測定］
製造した光学素子は、８５℃、８５％、５００ｈの耐湿試験を行った後、それぞれ室温に戻して、亀裂（クラック）の発生の有無を観察して耐熱性を評価した。また、微小レンズについては、干渉計（Ｈｅ−Ｎｅレーザ、λ＝６３３ｎｍ）を用いて、球面収差、および基材表面への入射角１２°での絶対反射スペクトルを分光光度計を用いて測定し、その極小値の波長シフト量を、耐熱、耐湿試験前後で測定し、特性劣化を評価した。また、アッべ屈折率計を用いて、膜部分のｄ線の屈折率を測定した。
以下に本発明の光学素子の実施例について説明する。
【００６５】
〔成形用組成物の説明〕
〔成型用組成物Ｃ１〕前掲の一般化学式（化２）で示すフッ素化エポキシ化合物でｎ＝４とした化合物を６０重量部、非フッ素化エポキシ化合物として、脂環族エポキシ化合物である３，４−エポキシシクロヘキシルメチル（３，４−エポキシシクロヘキサン）カルボキシレート（化３）を４０重量部、重合開始剤としてカチオン系開始剤（Ｓ９）を１重量部、混合して成形用組成物Ｃ１を得た。この樹脂の硬化後の屈折率の温度係数ｄｎ／ｄＴは８９ｐｐｍ／℃、ガラス転移温度Ｔｇが１５０℃であった。
【００６６】
〔接着用組成物Ｃ２〕前掲の一般化学式（化２）でフッ素化エポキシ化合物でｎ＝４とした化合物を５０重量部、非フッ素化エポキシ化合物として、脂環族エポキシ化合物（化３）を４７重量部、シランカップリング剤として３−グリシドキシプロピルトリエトキシシラン（化１８）を１重量部、重合開始剤としてカチオン系開始剤（Ｓ９）を１重量部、酸化防止剤として９，１０−ジヒドロ−９−オキサ−１０−フォスファフェナンスレン−１０−オキサイドを２重量部混合して成形用組成物Ｃ２を得た。
【００６７】
〔成型用組成物Ｃ３〕前掲の一般化学式（化２）でフッ素化エポキシ化合物でｎ＝４とした化合物を６０重量部、非フッ素化エポキシ化合物として、脂環族エポキシ化合物（化３）を２０重量部、シランカップリング剤として３−グリシドキシプロピルトリエトキシシラン（化１８）を２０重量部、重合開始剤としてカチオン系開始剤（Ｓ９）を１重量部、混合して成形用組成物Ｃ３を得た。
【００６８】
〔成型用組成物Ｃ４〕前掲の一般化学式（化２）でフッ素化エポキシ化合物でｎ＝４とした化合物を５０重量部、非フッ素化エポキシ化合物として、脂環族エポキシ化合物（化３）を３０重量部、シランカップリング剤として３−グリシドキシプロピルトリエトキシシラン（化１８）を２０重量部、重合開始剤としてカチオン系開始剤（Ｓ９）を１重量部、混合して成形用組成物Ｃ４を得た。
【００６９】
〔成型用組成物Ｃ５〕前掲の一般化学式（化２）でフッ素化エポキシ化合物でｎ＝４とした化合物を４０重量部、非フッ素化エポキシ化合物として、脂環族エポキシ化合物（化３）を４５重量部、シランカップリング剤として３−グリシドキシプロピルトリエトキシシラン（化１８）を１５重量部、重合開始剤としてカチオン系開始剤（Ｓ９）を１重量部、混合して成形用組成物Ｃ５を得た。
【００７０】
〔成型用組成物Ｃ６〕非フッ素化エポキシ化合物として、脂環族エポキシ化合物（化３）を９０重量部、シランカップリング剤として３−グリシドキシプロピルトリエトキシシラン（化１８）を１０重量部と重合開始剤としてカチオン系開始剤（Ｓ９）を１重量部、混合して成型用組成物Ｃ６を得た。
【００７１】
〔成型用組成物Ｃ７〕前掲の一般化学式（化２）でフッ素化エポキシ化合物でｎ＝４とした化合物を２０重量部、非フッ素化エポキシ化合物として、脂環族エポキシ化合物（化３）を７０重量部、シランカップリング剤として３−グリシドキシプロピルトリエトキシシラン（化１８）を１０重量部、重合開始剤としてカチオン系開始剤（Ｓ９）を１重量部、混合して成形用組成物Ｃ７を得た。
【００７２】
〔成型用組成物Ｃ８〕前掲の一般化学式（化２）でフッ素化エポキシ化合物でｎ＝４とした化合物を８０重量部、非フッ素化エポキシ化合物として、脂環族エポキシ化合物（化３）を１０重量部、シランカップリング剤として３−グリシドキシプロピルトリエトキシシラン（化１８）を１０重量部、重合開始剤としてカチオン系開始剤（Ｓ９）を１重量部、混合して成形用組成物Ｃ８を得た。
【００７３】
〔成型用組成物Ｃ９〕非フッ素化エポキシ化合物として、脂環族エポキシ化合物（化３）を１０重量部、シランカップリング剤として３−グリシドキシプロピルトリエトキシシラン（化１８）を９０重量部と重合開始剤としてカチオン系開始剤（Ｓ９）を１重量部、混合して成型用組成物Ｃ９を得た。
【００７４】
［実施例１］
図２に示すような、ガラス基板２２上に反射防止膜付き樹脂製凸レンズアレイ１２０を形成する。ガラス基板２２として厚み３．０ｍｍで５０ｍｍ角の石英ガラスの基板（線膨張率：５．５×１０^−７℃^−１）を超音波アルカリ洗浄および純水洗浄した。成形樹脂として成形用組成物Ｃ１を用い、型注ぎ法により、この石英ガラス基板の片側表面に膜を形成して微細凹凸板を形成した。
【００７５】
成形型として、曲率半径１．７５ｍｍ、レンズ直径１．００ｍｍ、凹部の深さ７３μｍをもつ球面弧形状の凹部を縦方向に密接して５０個、横方向に密接して５０個、合計約２５００個有するガラス製成形型（厚み５ｍｍ、寸法５０ｍｍ×５０ｍｍ）を用いた。この型には離型性を向上させるため、表面にフッ素樹脂をスピンコート法により成膜した。
【００７６】
成形用組成物Ｃ１は厚さ約１００μｍとなるように塗布した。紫外線は基板側から強度１２０ｍＷ／ｃｍ^２、室温で３分間の条件で照射した。離型後の最終加熱条件は１５０℃、６０分であった。
【００７７】
成形後の樹脂硬化膜３４の最も薄い領域の膜厚ｄは約２０μｍ、球面状凸部頂上からの最大膜厚Ｄは９１．５μｍであった。膜は透明で屈折率は１．４６であり、石英ガラス基板との屈折率の整合がよいため挿入損失は−０．５ｄＢ以下と基板との界面での反射損失は極めて小さかった。膜中にはフッ素化アルキル基部分［−ＣＨ_２ （ＣＦ_２）_４ＣＨ_２−］が含まれていた。
【００７８】
その後基板温度２００℃昇温させた後、蒸着法により密着強化層４２としてＳｉＯ_２（１００ｎｍ）を成膜した。連続して反射防止膜４５として、ＴｉＯ_２（７４．８ｎｍ）／ＳｉＯ_２（６４．８ｎｍ）／ＴｉＯ_２（１８９．７ｎｍ）／ＳｉＯ_２（２６６．５ｎｍ）を成膜した。
この微小凸レンズ（マイクロレンズ）５０の焦点距離は、３．２９７〜３．３００ｍｍであった。
【００７９】
この凸レンズアレイ基板内からランダムに選んだ１００点の球面凸部について測定したところ、平均高さ７１．５μｍ、標準偏差０．１２μｍであった。これから計算される硬化膜の収縮率は約２％であり、このマイクロレンズ５０のＨｅ−Ｎｅレーザ（λ＝６３３ｎｍ）により測定した球面収差は、ＲＭＳ＝０．０５λ、標準偏差０．００１λであった。
【００８０】
この凸レンズアレイ基板の耐湿性評価を行った結果、膜に亀裂や剥離は生じず、すべての凸部の焦点距離は−２０〜８５℃の温度範囲において３．２９７〜３．３００ｍｍの範囲にあって耐湿試験前と変わらず、また膜の反対側から垂直に平行光を入射させて集光スポットの直径を測定したところ、すべての凸部レンズについて集光スポットの直径は３μｍ以内であり、耐湿試験前の値と変わらなかった。
【００８１】
また反射防止膜の特性を評価するため、分光光度計により反射スペクトルを測定したところ、その極小値は全く変動していなかった。走査電子顕微鏡での無反射膜の断面観察においても、膜中に１０ｎｍ以上の粒塊や、柱状構造の無い緻密な膜の形成が確認された。
【００８２】
［実施例２］
成型材料として、成形用組成物Ｃ２を用いて、実施例１と同様に凸レンズアレイ基板を形成したところ、最も薄い領域の膜厚ｄは約３０μｍであった。膜は透明で屈折率は１．４７６であり、石英ガラス基板との屈折率の整合がよいため挿入損失は−０．５ｄＢ以下と基板との界面での反射損失は極めて小さかった。また、実施例１同様の構成で、基板温度１５０℃で成膜した反射防止膜にはクラック等の異常は認められなかった。
【００８３】
凸レンズ（マイクロレンズ）の焦点距離は、−２０〜８５℃の全温度範囲で３．２９７〜３．３００ｍｍであった。この凸レンズ基板の凸部の高さは、ランダムに選んだ１００点の球面凸部について測定したところ、平均高さ７１．５μｍ、標準偏差０．１２μｍであった。これから計算される硬化膜の収縮率は約２％であり、このマイクロレンズのＨｅ−Ｎｅレーザ（λ＝６３３ｎｍ）により測定した球面収差は、ＲＭＳ＝０．０５λ、標準偏差０．００１λであった。
【００８４】
この凸レンズ基板の耐湿性評価を行った結果、膜に亀裂や剥離は生じず、すべての凸部の焦点距離は３．２９７〜３．３００ｍｍの範囲にあって耐湿試験前と変わらず、また膜の反対側から垂直に平行光を入射させて集光スポットの直径を測定したところ、すべての凸部レンズについて集光スポットの直径は３μｍ以内であり、耐湿試験前の値と変わらなかった。無反射膜の特性を評価するため、分光光度計により反射スペクトルを測定したところ、その極小値の変動は２０ｎｍと非常に小さかった。
【００８５】
［実施例３］
成型材料として、成形用組成物Ｃ３を用いて、実施例１と同様に微細凹凸基板を形成したところ、最も薄い領域の膜厚ｄは約３０μｍであった。膜は透明で屈折率は１．４６７であり、石英基板との屈折率の整合がよいため挿入損失は−０．５ｄＢ以下と基板との界面での反射損失は極めて小さかった。また、実施例１同様の構成で、基板温度１２０℃で成膜した反射防止膜にはクラック等の異常は認められなかった。
【００８６】
凸レンズ（マイクロレンズ）の焦点距離は、３．３００〜３．３０３ｍｍであった。この膜付き板（微細凹凸板）の凸部の高さは、ランダムに選んだ１００点の球面凸部について測定したところ、平均高さ７２．３μｍ、標準偏差０．１３μｍであった。これから計算される硬化膜の収縮率は約２％であり、このマイクロレンズのＨｅ−Ｎｅレーザー（λ＝６３３ｎｍ）により測定した球面収差は、ＲＭＳ＝０．０５λ、標準偏差０．００１λであった。
【００８７】
この試料の耐湿性評価を行った結果、膜に亀裂や剥離は生じず、すべての凸部の焦点距離は３．３００〜３．３０３ｍｍの範囲にあって耐湿試験前と変わらず、また膜の反対側から垂直に平行光を入射させて集光スポットの直径を測定したところ、すべての凸部レンズについて集光スポットの直径は３μｍ以内であり、耐湿試験前の値と変わらなかった。反射防止膜の特性を評価するため、分光光度計により反射スペクトルを測定したところ、その極小値の変動は５０ｎｍと小さかった。
［実施例４］
成型材料として、成形用組成物Ｃ４を用いて、実施例１と同様に凸レンズアレイ基板を形成したところ、最も薄い領域の膜厚ｄは約２５μｍであった。膜は透明で屈折率は１．４７６であり、石英ガラス基板との屈折率の整合がよいため挿入損失は−０．５ｄＢ以下と基板との界面での反射損失は極めて小さかった。また、実施例１同様の構成で、基板温度１５０℃で成膜した反射防止膜にはクラック等の異常は認められなかった。
【００８８】
凸レンズ（マイクロレンズ）の焦点距離は、−２０〜８５℃の全温度範囲で３．２９７〜３．３００ｍｍであった。この凸レンズ基板の凸部の高さは、ランダムに選んだ１００点の球面凸部について測定したところ、平均高さ７１．５μｍ、標準偏差０．１２μｍであった。これから計算される硬化膜の収縮率は約２％であり、このマイクロレンズのＨｅ−Ｎｅレーザ（λ＝６３３ｎｍ）により測定した球面収差は、ＲＭＳ＝０．０５λ、標準偏差０．００１λであった。
【００８９】
この凸レンズ基板の耐湿性評価を行った結果、膜に亀裂や剥離は生じず、すべての凸部の焦点距離は３．２９７〜３．３００ｍｍの範囲にあって耐湿試験前と変わらず、また膜の反対側から垂直に平行光を入射させて集光スポットの直径を測定したところ、すべての凸部レンズについて集光スポットの直径は３μｍ以内であり、耐湿試験前の値と変わらなかった。無反射膜の特性を評価するため、分光光度計により反射スペクトルを測定したところ、その極小値の変動は２０ｎｍと非常に小さかった。
【００９０】
［実施例５］
成型材料として、成形用組成物Ｃ５を用いて、実施例１と同様に凸レンズアレイ基板を形成したところ、最も薄い領域の膜厚ｄは約３０μｍであった。膜は透明で屈折率は１．４７７であり、石英ガラス基板との屈折率の整合がよいため挿入損失は−０．５ｄＢ以下と基板との界面での反射損失は極めて小さかった。また、実施例１同様の構成で、基板温度１５０℃で成膜した反射防止膜にはクラック等の異常は認められなかった。
【００９１】
凸レンズ（マイクロレンズ）の焦点距離は、−２０〜８５℃の全温度範囲で３．２９７〜３．３００ｍｍであった。この凸レンズ基板の凸部の高さは、ランダムに選んだ１００点の球面凸部について測定したところ、平均高さ７１．５μｍ、標準偏差０．１２μｍであった。これから計算される硬化膜の収縮率は約２％であり、このマイクロレンズのＨｅ−Ｎｅレーザ（λ＝６３３ｎｍ）により測定した球面収差は、ＲＭＳ＝０．０５λ、標準偏差０．００１λであった。
【００９２】
この凸レンズ基板の耐湿性評価を行った結果、膜に亀裂や剥離は生じず、すべての凸部の焦点距離は３．２９７〜３．３００ｍｍの範囲にあって耐湿試験前と変わらず、また膜の反対側から垂直に平行光を入射させて集光スポットの直径を測定したところ、すべての凸部レンズについて集光スポットの直径は３μｍ以内であり、耐湿試験前の値と変わらなかった。無反射膜の特性を評価するため、分光光度計により反射スペクトルを測定したところ、その極小値の変動は２０ｎｍと非常に小さかった。
【００９３】
［比較例１］
実施例１で用いた成形用組成物Ｃ１の代わりに成形用組成物Ｃ６を用い、その他は実施例１と同じ基材および成形型を用いて実施例１に記載の方法で凸レンズアレイ基板を形成した。
得られた膜は最も薄い領域の膜厚ｄは約６０μｍであった。また、実施例１同様の構成で、基板温度１５０℃で成膜した反射防止膜にはクラック等の異常は認められなかった。
【００９４】
凸レンズ（マイクロレンズ）の焦点距離は、−２０〜８５℃の全温度範囲で３．２９７〜３．３００ｍｍであった。この凸レンズ基板の凸部の高さは、ランダムに選んだ１００点の球面凸部について測定したところ、平均高さ７１．５μｍ、標準偏差０．１２μｍであった。これから計算される硬化膜の収縮率は約２％であり、このマイクロレンズのＨｅ−Ｎｅレーザ（λ＝６３３ｎｍ）により測定した球面収差は、ＲＭＳ＝０．０５λ、標準偏差０．００１λであった。
【００９５】
この凸レンズ基板の耐湿性評価を行った結果、膜に亀裂や剥離は生じず、すべての凸部の焦点距離は３．２９７〜３．３００ｍｍの範囲にあって耐湿試験前と変わらず、また膜の反対側から垂直に平行光を入射させて集光スポットの直径を測定したところ、すべての凸部レンズについて集光スポットの直径は３μｍ以内であり、耐湿試験前の値と変わらなかった。しかし硬化物の屈折率を測定したところ１．５２であり、石英ガラス基板との界面反射により挿入損失が１．０ｄＢ発生した。
【００９６】
［比較例２］
実施例１で用いた成形用組成物Ｃ１の代わりに成形用組成物Ｃ７を用い、その他は実施例１と同じ基材および成形型を用いて実施例１に記載の方法で凸レンズアレイ基板を形成した。
得られた膜は最も薄い領域の膜厚ｄは約５０μｍであった。また、実施例１同様の構成で、基板温度１５０℃で成膜した反射防止膜にはクラック等の異常は認められなかった。しかし、硬化物の屈折率は１．５０であり、石英ガラス基板との界面反射による挿入損失が０．８ｄＢ発生した。
【００９７】
［比較例３］
実施例１で用いた成形用組成物Ｃ１の代わりに成形用組成物Ｃ８を用い、その他は実施例１と同じ基材および成形型を用いて実施例１に記載の方法で凸レンズアレイ基板を形成した。
【００９８】
得られた膜は最も薄い領域の膜厚ｄは約５０μｍであった。また、実施例１同様の構成で、基板温度１５０℃で成膜した反射防止膜にはクラック等の異常は認められなかった。しかし、硬化物の屈折率は１．４１であり、石英ガラス基板との界面反射による挿入損失が０．８ｄＢ発生した。
【００９９】
［比較例４］
実施例１で用いた成形用組成物Ｃ１の代わりに成形用組成物Ｃ９を用い、その他は実施例１と同じ基材および成形型を用いて実施例１に記載の方法で凸レンズアレイ基板を形成した。
【０１００】
得られた膜は最も薄い領域の膜厚ｄは約３５μｍであった。また、実施例１同様の構成で、基板温度１５０℃で成膜した反射防止膜にはクラック等の異常は認められなかった。しかし、硬化物の屈折率は１．４９であり、石英ガラス基板との界面反射による挿入損失が０．７ｄＢ発生した。
【０１０１】
以上の実施例、比較例から勘案し、本発明においては好ましい成形用樹脂組成物の組成範囲を、図３に示すように、３つの化合物（Ａ）、（Ｂ）、（Ｃ）からなる組成で規定する。ただし、化合物（Ａ）は、前掲の一般式（化２）で表されるフッ素化エポキシ化合物で、式中ＲはＣＨ_２（ＣＦ_２）_ｎＣＨ_２を示し、ｎは１〜４の整数である。また、化合物（Ｂ）は非フッ素化エポキシ化合物、化合物（Ｃ）はシランカップリング剤である。
【０１０２】
化合物（Ａ）、（Ｂ）、（Ｃ）の重量％を単位とする重量比をｗ_Ａ、ｗ_Ｂ、ｗ_Ｃとするとき、前記各化合物が１００重量％である点を図３の組成図の各頂点Ａ、Ｂ、Ｃとし、座標（ｗ_Ａ，ｗ_Ｂ，ｗ_Ｃ）で組成を表す。
【０１０３】
この組成図において、組成物Ｃ１（実施例１）は点（６０，４０，０）、組成物Ｃ２（実施例２）は点（５０，４９，１）、組成物Ｃ３（実施例３）は点（６０，２０，２０）、組成物Ｃ４（実施例４）は点（５０，３０，２０）、組成物Ｃ５（実施例５）は点（４０，４５，１５）にそれぞれ相当する。
また、組成物Ｃ６（比較例１）は点（０，９０，１０）、組成物Ｃ７（比較例２）は点（２０，７０，１０）、組成物Ｃ８（比較例３）は点（８０，１０，１０）、組成物Ｃ９（比較例４）は点（０，１０，９０）にそれぞれ相当する。
【０１０４】
以上の実施例、比較例より、実施例の各組成が含まれるつぎの点、Ｄ（８０， ２０，０）、Ｅ（５０， ２０， ３０）、Ｆ（３０， ４０， ３０）、Ｇ（３０， ７０， ０）で囲まれた 四角形ＤＥＦＧ内にある組成が好ましいと言え、Ｄ（８０， ２０， ０）、Ｈ（６０， ２０， ２０）、Ｉ（３０， ５０， ２０）、Ｇ（３０， ７０， ０）で囲まれた四角形ＤＨＩＧ内にある組成がより好ましい。さらに、実施例１および２の組成が含まれるＫ（７０， ３０， ０）、Ｌ（７０， ２０， １０）、Ｍ（４０， ５０， １０）、Ｎ（４０， ６０， ０）で囲まれた四角形ＫＬＭＮ内にある組成がもっとも望ましい。この範囲において硬化後の樹脂組成物の屈折率は１．４５〜１．４８の範囲となり、石英ガラスの屈折率とよく整合する。
【０１０５】
上記実施例では、化合物（Ａ）のフッ素化エポキシ化合物でｎ＝４の例を示しているが、ｎ＝１〜３であってもよい。また化合物（Ｂ）は脂環族エポキシ化合物のうち、３，４−エポキシシクロヘキシルメチル（３，４−エポキシシクロヘキサン）カルボキシレートを使用したが、他の脂環族エポキシ化合物あるいは芳香族エポキシ化合物を用いることもできる。シランカップリング剤も３−グリシドキシプロピルトリエトキシシランに限らず、他の化合物であってもよい。
【０１０６】
上記実施例では基材として石英ガラス基板を使用し、固体組成物層の屈折率をこれに一致させるように組成を調整した。本発明の成形用組成物を用いた場合、組成の調整によって硬化後の屈折率を一定の範囲で設定できる。したがって石英ガラス以外の基材を使用する場合も他の性能を維持しつつ屈折率を調整することができる。
【０１０７】
【発明の効果】
以上、説明したように、本発明の成形用樹脂組成物は成形の際の熱収縮が小さく寸法精度の高い微細凹凸構造を提供することができる。また、耐熱性が高く、所望の特性および耐久性を有する誘電体多層膜を硬化後の組成物層上に形成することができる。また基材と屈折率を整合させることが可能である。
【図面の簡単な説明】
【図１】本発明の光学素子の製造工程を示す図である。
【図２】本発明の実施例の微小レンズアレイの構成を示す模式図である。
【図３】本発明の成形用樹脂組成物の組成範囲を示す図である。
【符号の説明】
１０ 成形型
２０ 基材
２２ ガラス基板
３０ 成形用組成物
３２ 固体組成物層
３４ 樹脂硬化膜
４０ 誘電体多層膜
４２ 密着強化層
４５ 反射防止膜
５０ 微小レンズ
１００ 光学素子
１２０ 凸レンズアレイ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical element having a predetermined surface shape such as a diffraction grating, a Fresnel lens or a flat lens array mainly used in the field of optical communication, and in particular, a molding resin suitable for producing the predetermined surface shape by a molding technique. Composition.
[0002]
[Prior art]
With an increase in information communication capacity, optical elements such as diffraction gratings and microlens arrays (microlens arrays) have been increasingly used in the field of optical communication. These optical elements are flat optical elements that utilize a diffraction or refraction effect of light by providing a predetermined minute uneven structure on the surface.
[0003]
Various methods are known for forming the uneven structure on the surface, and a resin molding technique is known as a method suitable for mass production at low cost. For example, Patent Document 1 discloses a method in which a monomer of an ultraviolet curable resin is uniformly spread on a base material and irradiated with ultraviolet light while being in contact with a mold having an uneven structure.
[0004]
On the other hand, in optical communication, it is required to prevent reflected return light from being transmitted through an optical path. In particular, it is necessary that the reflection from the interface between the end face of the silica-based optical fiber used in optical communication and the optical element be sufficiently small. The most common method of preventing such reflection is to form a dielectric multilayer film on the surface of the optical element.
[0005]
[Patent Document 1]
JP-A-63-49702
[0006]
[Problems to be solved by the invention]
However, in the resin molding technique described above, the ultraviolet curable monomer shrinks greatly during the photopolymerization process, and sometimes the design dimensional accuracy required for the optical element cannot be satisfied. Also, the resin has a problem in heat resistance, and it is necessary to keep the substrate temperature low when forming the dielectric multilayer film, and thus there is a problem in the film quality of the dielectric multilayer film and its durability. Furthermore, since the conventionally used resin has a large difference in refractive index from the substrate, reflection loss occurs at the interface between the substrate and the resin, and there has been a problem that the performance required for the optical element cannot be sufficiently satisfied.
[0007]
The present invention has been made in order to solve the problems existing in such a conventional technology, and an object thereof is to form a compact having high dimensional accuracy with small heat shrinkage during molding, and heat resistance. It is an object of the present invention to provide a resin composition for molding capable of forming a dielectric multilayer film having desired characteristics and durability on the surface of the molded body.
[0008]
It is still another object of the present invention to provide an optical element in which a fine concavo-convex structure is formed by molding, and an antireflection layer of a dielectric multilayer film is formed on the surface. In this case, the cured resin composition is transparent, and the purpose is to match the refractive index of the resin composition with the refractive index of the substrate.
[0009]
[Means for Solving the Problems]
After the resin composition for molding of the present invention is filled and pressed between the base material and the mold, a solid composition layer having a predetermined shape is obtained by applying at least one of heat and ultraviolet rays and polymerizing and curing. The composition includes a polymerizable organic group capable of flowing and has fluidity.
[0010]
Its composition is based on the following three types of compounds (A), (B) and (C) as main components, and the weight ratio of these compounds (A), (B) and (C) in units of% by weight is defined as: w _A , W _B , W _C , The points (100% by weight) of the respective compounds (A), (B) and (C) are defined as vertices A, B and C, respectively, and the coordinates (w _A , W _B , W _C ) And be within the square DEFG surrounded by D (80, 20, 0), E (50, 20, 30), F (30, 40, 30), and G (30, 70, 0). Is desirable.
[0011]
Further, it is more preferable that the inside of a square DHIG surrounded by D (80, 20, 0), H (60, 20, 20), I (30, 50, 20) and G (30, 70, 0) is more preferable. Most preferably, it is within a square KLMN surrounded by K (70, 30, 0), L (70, 20, 10), M (40, 50, 10), and N (40, 60, 0).
[0012]
However, the compound (A) is a fluorinated epoxy compound represented by the following general formula (Formula 2).
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Where R is CH ₂ (CF ₂ ) _n CH ₂ (N is a positive integer), and n is preferably 1 to 4.
[0013]
Compound (B) is a non-fluorinated epoxy compound, and is preferably an alicyclic epoxy compound. Compound (C) is a silane coupling agent. It is particularly preferred to contain an epoxy group, and particularly preferred to contain a γ-epoxy group or a cyclohexyl group.
[0014]
The above resin composition has high heat resistance, can form a dielectric multilayer film by increasing the substrate temperature to about 250 ° C., and can form a dense and highly weather-resistant film. This makes it possible to provide an optical element having an antireflection layer having high performance.
[0015]
Further, the resin composition after curing is transparent, and by selecting the above composition range, the refractive index substantially matches the refractive index of quartz glass of 1.46. Therefore, when the substrate is made of quartz glass, reflection at the solid composition layer-substrate interface can be reduced. Alternatively, when an optical element made of this resin composition is optically coupled to an optical fiber, reflection at the interface between the end face of the optical fiber and the surface of the resin composition can be suppressed.
[0016]
The molding resin composition preferably contains 0.1 to 7% by weight of a polymerization initiator for curing the composition. Further, it is preferable that the antioxidant is contained in an amount of 5% by weight or less to prevent deterioration, more preferably 2% by weight or less.
[0017]
When using a composition having the above composition and molding with a mold having a desired shape, and applying at least one of heat and ultraviolet rays to polymerize and cure to obtain a solid composition layer, heat shrinkage during molding is performed. Is small, so that a molded article having a small dimensional difference from a molding die can be formed. Further, the action of the antioxidant can prevent long-term deterioration of the molded product.
[0018]
The solid composition layer obtained by curing the molding resin composition of the present invention has a refractive index in the range of 1.45 to 1.48. As described above, when quartz glass having a refractive index of 1.46 is used as the base material, the refractive index of the solid composition layer is adjusted by adjusting the blending ratio of the above components (A), (B), and (C). Can be selected to a value that substantially matches the refractive index of the substrate within a predetermined range, so that reflection at the solid composition layer-substrate interface can be suppressed.
[0019]
The optical element of the present invention is a solid having a predetermined shape obtained by applying the above-mentioned resin composition for molding, filling and pressing between a substrate and a molding die, and then applying and curing at least one of heat and ultraviolet rays. After forming the composition layer, at least two dielectric films are laminated on the surface.
This dielectric multilayer film functions as an antireflection film, and can suppress the reflection of incident light in an optical element used by allowing light to enter the surface of the solid composition layer and transmitting the light toward the substrate side.
[0020]
Further, it is preferable that the base material of the optical element is quartz glass. The resin composition for molding of the present invention can have the refractive index after curing substantially equal to that of quartz glass, and therefore can suppress reflection at the interface between the solid composition layer and the substrate.
[0021]
The optical element of the present invention can have a function of a transmission type diffraction grating, a Fresnel lens, or a microlens array by selecting a surface shape.
[0022]
Since the molding technique is used, these optical elements can be provided in large quantities and at low cost. In addition, since the molding resin composition of the present invention has a small shrinkage at the time of molding, the shape of a molding die in which a desired design shape is accurately produced can be accurately transferred. In addition, these optical elements are used in such a manner that light is incident on the surface of the solid composition layer having a predetermined surface shape and transmitted to the substrate side, and an antireflection film made of a dielectric multilayer film is used on the surface. In addition, the refractive index of the solid composition layer can be matched with the refractive index of the substrate, so that an optical element with low reflection loss can be realized.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
In the present invention, a solid composition is formed by polymerizing and curing a compound having fluidity. In order to form a predetermined surface irregular shape, the above compound is closely adhered between a substrate and a mold and sandwiched in a film shape, and then one or both of heat and ultraviolet light is applied, and this is polymerized and cured by the energy. Let it. The cured composition is released from the mold, and then heated if necessary, so that a shape obtained by inverting the surface shape of the mold is transferred to the surface of the composition.
[0024]
In order to cause polymerization curing as described above, this compound needs to have at least one polymerizable organic group in its molecule. Photopolymerization is caused by addition polymerization of radicals or cations generated by photolysis of a polymerization initiator to polymerizable organic groups. Therefore, shrinkage is smaller than in the dehydration condensation reaction, and a chemically bonded uniform film can be instantaneously formed. In the case of thermal polymerization, it depends on thermal decomposition of a polymerization initiator. Therefore, an organic group polymerized by light or heat is used as the polymerizable organic group.
[0025]
Examples of the photopolymerizable organic group include an epoxy group, an acryloxy group, a methacryloxy group, a vinyl group, and an organic group containing these groups. Examples of the thermally polymerizable organic group include an epoxy group, a vinyl group, and an organic group containing these.
[0026]
Examples of the liquid polymerizable compound having an epoxy group include fluorinated epoxy compounds and non-fluorinated epoxy compounds such as alicyclic epoxy compounds and aromatic epoxy compounds. In the present invention, a fluorinated epoxy compound and a non-fluorinated epoxy compound are mixed and used as shown below.
[0027]
In the present invention, as the fluorinated epoxy compound, a compound represented by the aforementioned general formula (Formula 2) is used.
Examples of the alicyclic epoxy resin used by being mixed with the fluorinated epoxy compound include a compound represented by the following structural formula.
[0028]
3,4-epoxycyclohexylmethyl (3,4-epoxycyclohexane) carboxylate (formula 3),
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Vinylcyclohexene diepoxide (Formula 4),
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3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate (Formula 5),
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Bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate (formula 6),
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Dicyclopentadiene oxide (Formula 7),
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Bis (2,3-epoxycyclopentyl) ether, limonene dioxide
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However, it is preferably used from the viewpoints of easy handling in terms of heat resistance, chemical resistance and viscosity of the liquid, curability, and availability of raw materials.
[0029]
In addition, a group of compounds represented by the chemical formula (Formula 9) can also be used.
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As the aromatic epoxy compound, a compound represented by the general formula (Formula 10)
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In which X is a compound represented by the following chemical formula (Chemical Formulas 11 to 14). Among these, bisphenol A type (formula 11),
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Biphenyl type (Chemical formula 12),
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Bisphenol F type (formula 13),
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Diphenyl ether type (formula 14),
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Bisphenol S type (Formula 15),
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Other compounds (Formula 16)
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And the like are preferably used from the viewpoints of easy handling, curability, and availability of raw materials from the viewpoints of heat resistance, chemical resistance, and liquid viscosity.
[0030]
Further, a silane coupling agent may be added in order to improve the adhesion to the substrate and the moisture resistance. Examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane (Formula 17),
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3-glycidoxypropyltriethoxysilane (formula 18),
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Alternatively, 2- (3,4-epoxycyclohexylethyltrimethoxysilane, 2- (3,4-epoxycyclohexylethyltriethoxysilane (Chem. 19) can be used.
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[0031]
When the polymerizable organic group contained in the molding composition is photopolymerizable, a photopolymerization initiator is added. Examples of the radical photopolymerization initiator include [2-hydroxy-2-methyl-1-phenylpropan-1-one] (abbreviated as S1; the same applies hereinafter), [1- (4-isopropylphenyl) -2-hydroxy- 2-methylpropan-1-one] (S2), [4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propylketone)] (S3), [2,2-dimethoxy-1,2-diphenyl [Ethane-1-one] (S4), [1-hydroxy-cyclohexyl-phenyl-ketone] (S5), [2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one]. (S6), [bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide] (S7), [2-benzyl-2-dimethylamido] 1-1-(4-morpholinophenyl) - butanone -1] can be exemplified (S8).
[0032]
Examples of the cationic photopolymerization initiator include phenyl- [m- (2-hydroxytetradecyclo) phenyl] iodonium hexafluoroantimonate (S9) and diphenyliodonium tetrakis (pentafluorophenyl) borate (S10). . The amount of the photopolymerization initiator is preferably from 0.1 to 7% by weight based on the total weight of the liquid composition.
[0033]
In addition, a phosphoric acid compound may be added as an antioxidant. 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide can be exemplified. The content is preferably 5% or less, more preferably 2% or less, based on the main component.
[0034]
Since the predetermined surface shape of the optical element of the present invention is formed by molding, the compound containing the polymerizable organic group needs to have fluidity, and its viscosity is preferably adjusted to 3 to 2500 mPa · m, 100 to 1500 mPa · m is more preferable, and 100 to 1000 mPa · m is most preferable.
[0035]
As a process of molding an optical element having a predetermined surface shape, the following two methods can be typically given.
In the first method (hereinafter referred to as a mold pouring method), a molding composition is poured into a mold and degassed. Next, the mold and the substrate are joined, and heating or ultraviolet irradiation is performed. This cures the composition. The composition on the cured substrate is released from the mold, and then heated if necessary.
[0036]
The above method will be described in detail with reference to FIG. The mold 10 having a predetermined minute uneven shape on its surface is kept horizontal with the mold surface facing upward, and a molding composition 30 having a viscosity of 100 to 1000 mPa · m is poured on the mold 10 to form a mold. (FIG. 1 (a)). Instead of pouring, the mold may be immersed in a bath of the molding composition or applied to the surface of the mold with a brush.
[0037]
In this state, the composition 30 filled on the mold 10 is kept at a temperature of from room temperature to about 100 ° C. at a reduced pressure of 2 to 5 Pa for 5 to 10 minutes so that the composition 30 does not contain air. Bubble and dissolved oxygen may be degassed.
Next, the substrate 20 is brought into contact with the composition 30 on the molding die 10 so as not to form a gap between the composition 30 and the surface of the substrate, and the composition 30 is layered between the substrate 20 and the molding die 10. (FIG. 1B). In this state, the composition is kept at 20 to 100 ° C. for 1 to 30 minutes while being irradiated with ultraviolet rays, or heated to 140 to 180 ° C. and kept for 10 to 120 minutes to polymerize and cure the composition.
[0038]
When irradiating ultraviolet rays, at least one of the substrate 20 and the mold 10 is made of a material that can transmit ultraviolet rays. Next, by peeling off the mold 10 and releasing the mold, a solid composition layer 32 having a high glass transition temperature and having a surface irregularity obtained by inverting the surface irregularity of the mold 10 is formed on the surface of the substrate 20. It is formed in a joined state (FIG. 1C).
[0039]
Then, if necessary, this is finally heated at 100 to 200 ° C. for 15 to 250 minutes under normal pressure or a reduced pressure of 2 to 5 Pa, so that the polymerization initiator remaining in the solid composition layer, unpolymerized Evaporate things. As a result, the solid composition layer slightly shrinks in volume in the thickness direction to form a dense film. By coating the thus formed solid composition layer 32 having a predetermined surface shape with the dielectric multilayer film 40 as shown in FIG. 1D, the optical element 100 of the present invention is obtained.
[0040]
In a second molding method (hereinafter, referred to as a substrate pouring method), a molding composition is directly poured onto a substrate surface, degassed, and then a molding die is pressed against the composition on the substrate surface, and ultraviolet light is irradiated as it is. Irradiation or heating and transfer molding. Thereafter, the mold is released, and final heating is performed as necessary.
[0041]
The above method is the same as the first method after FIG. The surface of the substrate to be coated is kept horizontal, and a composition having a viscosity of 100 to 1000 mPa · m is poured on the substrate and spread in a layer so as to have a predetermined thickness. In this state, the composition may be kept at room temperature to 100 ° C. and at a reduced pressure of 2 to 5 Pa for 5 to 10 minutes so that the composition does not contain air, and bubbles and dissolved oxygen in the liquid may be degassed.
[0042]
Then, a mold having a predetermined minute uneven shape on the surface is pressed onto the layered composition to apply a pressure of 0.5 to 120 kg / cm. ² It is held at a temperature of 20 ° C. to 150 ° C. for 60 seconds to 60 minutes, or pressed at the above pressure, and in that state, the irradiation intensity of the ultraviolet rays at the irradiation position is 1.0 to 120 mW / cm. ² While maintaining the temperature at 20 to 100 ° C. for 60 seconds to 30 minutes, the polymerization reaction of the molding composition is almost completed and cured.
[0043]
When irradiating ultraviolet rays, at least one of the substrate and the mold is made of a material that can transmit ultraviolet rays. Then, the mold is peeled off and the mold is released, whereby a solid composition layer having an uneven shape obtained by inverting the uneven shape of the mold on the surface is formed in a state of being joined to the surface of the substrate.
[0044]
Then, if necessary, this is heated at 180 to 250 ° C. for 15 to 350 minutes under normal pressure or reduced pressure of 2 to 5 Pa, for example, to vaporize the photopolymerization initiator and unpolymerized material remaining in the layer. . As a result, the solid composition layer slightly shrinks in volume in the thickness direction to form a dense film.
[0045]
The optical element of the present invention can be obtained by coating the thus formed solid composition layer having a predetermined surface shape with a dielectric multilayer film.
[0046]
It is preferable to provide a release film made of a fluororesin or gold (Au) on the outermost surface of the mold used in the present invention. The fluororesin is uniformly formed on a mold by a spin or dipping method. Further, gold is a material excellent as a release film because it has good releasability to a molding material, mechanical strength capable of withstanding pressure, heat resistance, corrosion resistance, and oxidation resistance.
[0047]
The thickness of such a release film is preferably from 200 to 1000 nm, more preferably from 400 to 600 nm. The release film is more uniform and smoother by sputtering, vacuum evaporation, electroless plating, electrolytic plating, foil bonding, etc., because the smoother the surface, the higher the release properties. Is preferred.
[0048]
It is preferable to select a material having an expansion coefficient similar to that of the release film as the material of the mold core. Mold cores made of resin have the advantage that they can be easily micro-processed and easily formed into a desired shape, and glass or metal mold cores have high heat resistance and mechanical strength, and are durable. Are better.
[0049]
The mold in the present invention has a concave portion or a convex portion on its surface. Examples of the concavo-convex portion include a spherical shape, a conical shape, a pyramid shape, and a slit shape having an arbitrary cross section. The spherical, conical, and pyramidal shapes are provided in an entire area or a part of the release film. On the other hand, when a slit is provided as a concave portion, the slit may be provided in a linear or curved manner, and when a plurality of slits are provided, the slit may be provided in a concentric shape or a lattice shape.
[0050]
Thus, according to the present invention, it has a glass transition temperature of 100 ° C. or more, a maximum thickness (measured at the convex portion of the surface unevenness) of 1 μm to 1 mm, preferably 20 to 150 μm, A flat or curved plate having a surface with irregularities, for example, a surface having irregularities having a predetermined width (concavo-convex pitch) within a range of 1 μm to 500 μm and a predetermined height within a range of 5 to 500 μm; It is formed on a substrate in a shape.
[0051]
This film is rich in elasticity (less brittle), has high strength, and is unlikely to crack. Since no foaming is observed in the film during molding and shrinkage of the film during molding is small, excellent transferability with extremely high dimensional accuracy of fine irregularities on the film surface can be realized. Specifically, for example, when a large number of projections having a height of 20 to 100 μm are formed, the variation in the height of the projections on the film surface is 1 μm or less. The deviation of the interval between the convex portions on the film surface from the molding die is less than the measurement accuracy (0.2 μm).
[0052]
As the substrate used in the present invention, a substrate having a shape such as a flat plate or a curved plate is used. It is desirable that the amount of warpage of the substrate surface at 200 ° C. and 20 ° C. (the thermal deformation length in a direction perpendicular to the surface per unit length in the surface direction of the substrate) is within ± 5 μm per cm. . If the amount of warpage exceeds this range, the substrate and the film may peel or crack at the interface in the process of forming the film. Therefore, it is preferable to select the material, dimensions and shape of the substrate.
[0053]
Also, this base material is 1.5 × 10 ^-5 ° C ^-1 It preferably has the following coefficient of linear expansion. The coefficient of linear expansion of the substrate is 1.55 × 10 ^-5 ° C ^-1 Exceeds, for example, polypropylene (9 to 15 × 10 ^-5 ° C ^-1 This is because, in the case of a plastics base material having a large thermal expansion coefficient as in the case of (1), the base material and the film are peeled off at the interface during the molding process of the composition, or the film is cracked.
[0054]
1.5 × 10 for ordinary inorganic glass ^-5 ° C ^-1 It has the following linear expansion coefficient. Preferably, at least the surface of the substrate is an oxide. If the surface of the substrate in contact with the composition is not an oxide, the adhesive strength is reduced in the process of forming the film, and in some cases, the substrate and the film are separated at the interface.
[0055]
Preferred examples of the material of the base material include silicate glass including quartz glass, oxide glass such as borate glass and phosphate glass, quartz, ceramics, silicon, aluminum and other metals, and epoxy resin. And glass fiber reinforced polystyrene. The metal does not join the organopolysiloxane film as it is, but it can be used as a substrate if the surface of the metal is treated in advance with an oxidizing agent.
[0056]
Further, as a substrate in the present invention, if a material transparent to light having a wavelength used by the optical element, for example, visible light, ultraviolet light, or infrared light, the optical element according to the present invention can be used as a lens array, It can function as a transmission type optical element such as a grating (for example, an echelette diffraction grating, an echelon diffraction grating, an echelle diffraction grating, etc.) and a Fresnel lens.
Each step of manufacturing an optical element having a predetermined surface shape according to the present invention will be described more specifically.
[0057]
[Application of solution to mold or substrate]
The molding composition having light or thermosetting and fluidity was poured onto the surface of a transparent molding die by a mold pouring method to obtain a layer having a thickness of 50 μm to 1 mm (viscosity: 200 mPa · m). The same applies to the substrate pouring method.
[0058]
[Joining / irradiation / release]
In the case of the mold pouring method, after the surface of the substrate is brought into contact with the above composition, the composition is pressure-developed between the mold and the substrate, and in that state, the ultraviolet ray is irradiated for 0.5 to 30 minutes. And irradiate it with a substrate. Then, after the composition is completely cured, the mold is separated from the substrate and released.
In the case of the substrate pouring method, a transparent mold is pressed against the above-mentioned coating film, and ultraviolet rays are similarly irradiated for 0.5 to 30 minutes to bond the substrate to the substrate, and then the mold is released.
According to any of the above methods, a solid composition layer having a fine unevenness obtained by transferring the shape of a molding die was obtained in a state of being adhered to the substrate surface.
[0059]
[Final heating]
The heating condition for improving the denseness of the solid composition layer obtained by releasing the mold was 150 ° C. for 60 minutes.
[0060]
[Deposition of dielectric multilayer film]
The main purpose of the dielectric multilayer film used in the present invention is to prevent reflection from the surface of the optical element. To achieve the required anti-reflection properties, TiO ₂ / SiO ₂ , Ta ₂ O ₅ / SiO ₂ , ZrO ₂ / SiO ₂ And TiO ₂ / MgF ₂ The thickness and material of each layer are designed according to the required specifications such as the wavelength used, return light return loss, etc. The thickness of the single layer is usually desirably 1 to 600 nm, more preferably 10 to 400 nm.
[0061]
Since the denser the film, the higher the durability, it is preferable to form the film uniformly and densely by a sputtering method, a vacuum evaporation method, or the like. In addition, from the viewpoint of moisture resistance, the deposition temperature of the dielectric multilayer film is preferably set to 50 to 250 ° C, more preferably 80 to 250 ° C.
[0062]
In order to protect the shape formed on the surface of the solid composition layer and to enhance the adhesion to the antireflection film formed thereon, a SiO 2 layer is formed between the surface of the solid composition layer and the dielectric multilayer film. ₂ It is desirable to provide a layer. The material is SiO ₂ You can choose other than. The thickness is preferably 1 to 300 nm, more preferably 10 to 150 nm.
[0063]
[Measurement of variation in height of projection]
The variation in the height of the convex portion of the outermost layer was measured by measuring the height with a laser microscope.
[0064]
[Measurement of heat resistance and moisture resistance, optical properties]
The manufactured optical element was subjected to a humidity resistance test at 85 ° C., 85%, and 500 hours, then returned to room temperature, and observed for the occurrence of cracks (cracks) to evaluate heat resistance. For the microlens, the spherical aberration and the absolute reflection spectrum at an incident angle of 12 ° on the substrate surface were measured using a spectrophotometer using an interferometer (He-Ne laser, λ = 633 nm). The minimum wavelength shift amount was measured before and after the heat and humidity resistance test, and the characteristic deterioration was evaluated. The d-line refractive index of the film was measured using an Abbe refractometer.
Hereinafter, examples of the optical element of the present invention will be described.
[0065]
(Description of the molding composition)
[Molding composition C1] 60 parts by weight of a fluorinated epoxy compound represented by the aforementioned general formula (Chemical Formula 2) where n = 4, and a non-fluorinated epoxy compound as an alicyclic epoxy compound 3,4 -Epoxycyclohexylmethyl (3,4-epoxycyclohexane) carboxylate (Chemical Formula 3) (40 parts by weight) and a cationic initiator (S9) as a polymerization initiator (1 part by weight) were mixed to obtain a molding composition C1. . The temperature coefficient dn / dT of the refractive index of this resin after curing was 89 ppm / ° C, and the glass transition temperature Tg was 150 ° C.
[0066]
[Adhesive Composition C2] 50 parts by weight of the compound represented by the aforementioned general formula (Chemical Formula 2) in which n = 4 with a fluorinated epoxy compound, and 47 parts of an alicyclic epoxy compound (Chemical Formula 3) as a non-fluorinated epoxy compound. 1 part by weight of 3-glycidoxypropyltriethoxysilane (Chemical Formula 18) as a silane coupling agent, 1 part by weight of a cationic initiator (S9) as a polymerization initiator, and 9,10- 2 parts by weight of dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was mixed to obtain a molding composition C2.
[0067]
[Composition for molding C3] 60 parts by weight of a compound in which n = 4 with a fluorinated epoxy compound in the aforementioned general chemical formula (Chemical Formula 2), and 20 parts of an alicyclic epoxy compound (Chemical Formula 3) as a non-fluorinated epoxy compound. 20 parts by weight of 3-glycidoxypropyltriethoxysilane (Chemical Formula 18) as a silane coupling agent, and 1 part by weight of a cationic initiator (S9) as a polymerization initiator are mixed together to form a molding composition C3. Got.
[0068]
[Molding composition C4] 50 parts by weight of the compound of the above general formula (Chemical Formula 2) where n = 4 with a fluorinated epoxy compound, and 30 parts of an alicyclic epoxy compound (Chemical Formula 3) as a non-fluorinated epoxy compound. 20 parts by weight of 3-glycidoxypropyltriethoxysilane (Chemical Formula 18) as a silane coupling agent, and 1 part by weight of a cationic initiator (S9) as a polymerization initiator are mixed together to form a molding composition C4. Got.
[0069]
[Molding composition C5] 40 parts by weight of the compound represented by the aforementioned general formula (Chemical Formula 2) where n = 4 with a fluorinated epoxy compound, and 45 parts of an alicyclic epoxy compound (Chemical Formula 3) as a non-fluorinated epoxy compound. Parts by weight, 15 parts by weight of 3-glycidoxypropyltriethoxysilane (Chemical Formula 18) as a silane coupling agent, and 1 part by weight of a cationic initiator (S9) as a polymerization initiator. Got.
[0070]
[Composition for molding C6] 90 parts by weight of an alicyclic epoxy compound (Chemical Formula 3) as a non-fluorinated epoxy compound and 10 parts by weight of 3-glycidoxypropyltriethoxysilane (Chemical Formula 18) as a silane coupling agent And 1 part by weight of a cationic initiator (S9) as a polymerization initiator were mixed to obtain a molding composition C6.
[0071]
[Molding composition C7] 20 parts by weight of the compound of the above general formula (Chemical Formula 2) where n = 4 with a fluorinated epoxy compound, and 70% of an alicyclic epoxy compound (Chemical Formula 3) as a non-fluorinated epoxy compound. 10 parts by weight of 3-glycidoxypropyltriethoxysilane (Chemical Formula 18) as a silane coupling agent, and 1 part by weight of a cationic initiator (S9) as a polymerization initiator are mixed together to form a molding composition C7. Got.
[0072]
[Molding composition C8] 80 parts by weight of the fluorinated epoxy compound represented by the aforementioned general formula (Chemical Formula 2) where n = 4, and 10 parts of the alicyclic epoxy compound (Chemical Formula 3) as a non-fluorinated epoxy compound. Parts by weight, 10 parts by weight of 3-glycidoxypropyltriethoxysilane (Chemical Formula 18) as a silane coupling agent, and 1 part by weight of a cationic initiator (S9) as a polymerization initiator. Got.
[0073]
[Composition for molding C9] 10 parts by weight of an alicyclic epoxy compound (Chemical Formula 3) as a non-fluorinated epoxy compound and 90 parts by weight of 3-glycidoxypropyltriethoxysilane (Chemical Formula 18) as a silane coupling agent And 1 part by weight of a cationic initiator (S9) as a polymerization initiator were mixed to obtain a molding composition C9.
[0074]
[Example 1]
As shown in FIG. 2, a resin convex lens array 120 having an antireflection film is formed on a glass substrate 22. As a glass substrate 22, a 50 mm square quartz glass substrate having a thickness of 3.0 mm (linear expansion coefficient: 5.5 × 10 ^-7 ° C ^-1 ) Was subjected to ultrasonic alkali cleaning and pure water cleaning. Using the molding composition C1 as a molding resin, a film was formed on one surface of the quartz glass substrate by a mold pouring method to form a fine uneven plate.
[0075]
As a molding die, 50 spherical arc-shaped concave portions having a radius of curvature of 1.75 mm, a lens diameter of 1.00 mm, and a concave portion depth of 73 μm are closely contacted in the vertical direction and 50 in the horizontal direction, for a total of about 2500. A glass mold (thickness: 5 mm, dimensions: 50 mm × 50 mm) having two pieces was used. In this mold, a fluororesin was formed on the surface by spin coating in order to improve the releasability.
[0076]
The molding composition C1 was applied so as to have a thickness of about 100 μm. UV intensity is 120mW / cm from substrate side ² Irradiation at room temperature for 3 minutes. The final heating conditions after release were 150 ° C. for 60 minutes.
[0077]
The thickness d of the thinnest region of the cured resin film 34 after molding was about 20 μm, and the maximum thickness D from the top of the spherical projection was 91.5 μm. The film was transparent and had a refractive index of 1.46. Since the refractive index was well matched with the quartz glass substrate, the insertion loss was -0.5 dB or less, and the reflection loss at the interface with the substrate was extremely small. A fluorinated alkyl group moiety [-CH ₂ (CF ₂ ) ₄ CH ₂ −] Was included.
[0078]
Thereafter, the substrate temperature was raised to 200 ° C., and then SiO 2 was used as the adhesion reinforcing layer 42 by a vapor deposition method. ₂ (100 nm). TiO is continuously formed as the anti-reflection film 45. ₂ (74.8 nm) / SiO ₂ (64.8 nm) / TiO ₂ (189.7 nm) / SiO ₂ (266.5 nm).
The focal length of this micro convex lens (micro lens) 50 was 3.297 to 3.300 mm.
[0079]
Measurement was made on 100 spherical convex portions randomly selected from within the convex lens array substrate, and found to have an average height of 71.5 μm and a standard deviation of 0.12 μm. The contraction rate of the cured film calculated from this is about 2%, and the spherical aberration of this microlens 50 measured by a He-Ne laser (λ = 633 nm) is RMS = 0.05λ, standard deviation 0.001λ. Was.
[0080]
As a result of evaluating the moisture resistance of the convex lens array substrate, no cracks or peeling occurred in the film, and the focal lengths of all the convex portions were in the range of 3.297 to 3.300 mm in the temperature range of -20 to 85 ° C. The diameter of the focused spot was measured by applying parallel light perpendicularly from the opposite side of the film, and the diameter of the focused spot was within 3 μm for all convex lenses. It was not different from the value before the test.
[0081]
When the reflection spectrum was measured with a spectrophotometer to evaluate the characteristics of the antireflection film, the minimum value did not change at all. In observation of the cross-section of the non-reflective film with a scanning electron microscope, formation of a dense film having no particle mass of 10 nm or more and no columnar structure was confirmed in the film.
[0082]
[Example 2]
When a convex lens array substrate was formed in the same manner as in Example 1 using the molding composition C2 as a molding material, the film thickness d in the thinnest region was about 30 μm. The film was transparent and had a refractive index of 1.476. Since the refractive index was well matched to the quartz glass substrate, the insertion loss was -0.5 dB or less, and the reflection loss at the interface with the substrate was extremely small. Further, no abnormality such as a crack was observed in the antireflection film formed at a substrate temperature of 150 ° C. in the same configuration as in Example 1.
[0083]
The focal length of the convex lens (microlens) was 3.297 to 3.300 mm in the entire temperature range of -20 to 85 ° C. The height of the convex portion of this convex lens substrate was measured for 100 randomly selected spherical convex portions, and was found to have an average height of 71.5 μm and a standard deviation of 0.12 μm. The shrinkage of the cured film calculated from this was about 2%, and the spherical aberration of this microlens measured by a He-Ne laser (λ = 633 nm) was RMS = 0.05λ, standard deviation 0.001λ. .
[0084]
As a result of evaluating the moisture resistance of this convex lens substrate, no cracks or peeling occurred in the film, and the focal lengths of all the convex portions were in the range of 3.297 to 3.300 mm, which was the same as before the moisture resistance test. The diameter of the condensed spot was measured by making parallel light incident perpendicularly from the opposite side of the above, and the diameter of the condensed spot was within 3 μm for all the convex lenses, which was the same as the value before the moisture resistance test. When the reflection spectrum was measured with a spectrophotometer to evaluate the characteristics of the non-reflective film, the change in the minimum value was as small as 20 nm.
[0085]
[Example 3]
When a fine uneven substrate was formed in the same manner as in Example 1 using the molding composition C3 as a molding material, the thickness d of the thinnest region was about 30 μm. The film was transparent and had a refractive index of 1.467. Since the refractive index of the film was well matched to that of the quartz substrate, the insertion loss was -0.5 dB or less, and the reflection loss at the interface with the substrate was extremely small. Further, no abnormality such as a crack was observed in the antireflection film formed at a substrate temperature of 120 ° C. in the same configuration as in Example 1.
[0086]
The focal length of the convex lens (micro lens) was 3.300 to 3.303 mm. The height of the projections of this plate with a film (fine unevenness plate) was measured for 100 randomly selected spherical projections, and was found to have an average height of 72.3 μm and a standard deviation of 0.13 μm. The shrinkage of the cured film calculated from this was about 2%, and the spherical aberration of this microlens measured by a He-Ne laser (λ = 633 nm) was RMS = 0.05λ, standard deviation 0.001λ. .
[0087]
As a result of evaluating the moisture resistance of this sample, no crack or peeling occurred in the film, and the focal lengths of all the projections were in the range of 3.300 to 3.303 mm, which was the same as before the moisture resistance test, and The diameter of the condensed spot was measured by making parallel light incident perpendicularly from the opposite side, and the diameter of the condensed spot was within 3 μm for all convex lenses, which was the same as the value before the moisture resistance test. When a reflection spectrum was measured with a spectrophotometer to evaluate the characteristics of the antireflection film, the change in the minimum value was as small as 50 nm.
[Example 4]
When a convex lens array substrate was formed in the same manner as in Example 1 using the molding composition C4 as a molding material, the film thickness d in the thinnest region was about 25 μm. The film was transparent and had a refractive index of 1.476. Since the refractive index was well matched to the quartz glass substrate, the insertion loss was -0.5 dB or less, and the reflection loss at the interface with the substrate was extremely small. Further, no abnormality such as a crack was observed in the antireflection film formed at a substrate temperature of 150 ° C. in the same configuration as in Example 1.
[0088]
The focal length of the convex lens (microlens) was 3.297 to 3.300 mm in the entire temperature range of -20 to 85 ° C. The height of the convex portion of this convex lens substrate was measured for 100 randomly selected spherical convex portions, and was found to have an average height of 71.5 μm and a standard deviation of 0.12 μm. The shrinkage of the cured film calculated from this was about 2%, and the spherical aberration of this microlens measured by a He-Ne laser (λ = 633 nm) was RMS = 0.05λ, standard deviation 0.001λ. .
[0089]
As a result of evaluating the moisture resistance of the convex lens substrate, no cracks or peeling occurred in the film, and the focal lengths of all the convex portions were in the range of 3.297 to 3.300 mm, which was the same as before the moisture resistance test. The diameter of the condensed spot was measured by making parallel light incident perpendicularly from the opposite side of the above, and the diameter of the condensed spot was within 3 μm for all the convex lenses, which was the same as the value before the moisture resistance test. When the reflection spectrum was measured with a spectrophotometer to evaluate the characteristics of the non-reflective film, the change in the minimum value was as small as 20 nm.
[0090]
[Example 5]
When a convex lens array substrate was formed in the same manner as in Example 1 using the molding composition C5 as a molding material, the film thickness d in the thinnest region was about 30 μm. The film was transparent and had a refractive index of 1.477. Since the refractive index was well matched with the quartz glass substrate, the insertion loss was -0.5 dB or less, and the reflection loss at the interface with the substrate was extremely small. Further, no abnormality such as a crack was observed in the antireflection film formed at a substrate temperature of 150 ° C. in the same configuration as in Example 1.
[0091]
The focal length of the convex lens (microlens) was 3.297 to 3.300 mm in the entire temperature range of -20 to 85 ° C. The height of the convex portion of this convex lens substrate was measured for 100 randomly selected spherical convex portions, and was found to have an average height of 71.5 μm and a standard deviation of 0.12 μm. The shrinkage of the cured film calculated from this was about 2%, and the spherical aberration of this microlens measured by a He-Ne laser (λ = 633 nm) was RMS = 0.05λ, standard deviation 0.001λ. .
[0092]
As a result of evaluating the moisture resistance of the convex lens substrate, no cracks or peeling occurred in the film, and the focal lengths of all the convex portions were in the range of 3.297 to 3.300 mm, which was the same as before the moisture resistance test. The diameter of the condensed spot was measured by making parallel light incident perpendicularly from the opposite side of the above, and the diameter of the condensed spot was within 3 μm for all the convex lenses, which was the same as the value before the moisture resistance test. When the reflection spectrum was measured with a spectrophotometer to evaluate the characteristics of the non-reflective film, the change in the minimum value was as small as 20 nm.
[0093]
[Comparative Example 1]
A convex lens array substrate was formed by the method described in Example 1 using the molding composition C6 in place of the molding composition C1 used in Example 1, and using the same base material and mold as in Example 1 except for the above. did.
In the obtained film, the thickness d of the thinnest region was about 60 μm. Further, no abnormality such as a crack was observed in the antireflection film formed at a substrate temperature of 150 ° C. in the same configuration as in Example 1.
[0094]
The focal length of the convex lens (microlens) was 3.297 to 3.300 mm in the entire temperature range of -20 to 85 ° C. The height of the convex portion of this convex lens substrate was measured for 100 randomly selected spherical convex portions, and was found to have an average height of 71.5 μm and a standard deviation of 0.12 μm. The shrinkage of the cured film calculated from this was about 2%, and the spherical aberration of this microlens measured by a He-Ne laser (λ = 633 nm) was RMS = 0.05λ, standard deviation 0.001λ. .
[0095]
As a result of evaluating the moisture resistance of the convex lens substrate, no cracks or peeling occurred in the film, and the focal lengths of all the convex portions were in the range of 3.297 to 3.300 mm, which was the same as before the moisture resistance test. The diameter of the condensed spot was measured by making parallel light incident perpendicularly from the opposite side of the above, and the diameter of the condensed spot was within 3 μm for all the convex lenses, which was the same as the value before the moisture resistance test. However, when the refractive index of the cured product was measured, it was 1.52, and an insertion loss of 1.0 dB occurred due to interfacial reflection with the quartz glass substrate.
[0096]
[Comparative Example 2]
A convex lens array substrate was formed by the method described in Example 1 using the molding composition C7 in place of the molding composition C1 used in Example 1, and using the same base material and mold as in Example 1 except for the above. did.
In the obtained film, the thickness d of the thinnest region was about 50 μm. Further, no abnormality such as a crack was observed in the antireflection film formed at a substrate temperature of 150 ° C. in the same configuration as in Example 1. However, the cured product had a refractive index of 1.50, and an insertion loss of 0.8 dB occurred due to reflection at the interface with the quartz glass substrate.
[0097]
[Comparative Example 3]
A convex lens array substrate was formed by the method described in Example 1 using the molding composition C8 in place of the molding composition C1 used in Example 1, and using the same base material and molding die as in Example 1 except for the above. did.
[0098]
In the obtained film, the thickness d of the thinnest region was about 50 μm. Further, no abnormality such as a crack was observed in the antireflection film formed at a substrate temperature of 150 ° C. in the same configuration as in Example 1. However, the cured product had a refractive index of 1.41, and an insertion loss of 0.8 dB occurred due to reflection at the interface with the quartz glass substrate.
[0099]
[Comparative Example 4]
A convex lens array substrate was formed by the method described in Example 1 using the molding composition C9 in place of the molding composition C1 used in Example 1, and using the same base material and molding die as in Example 1 except for the above. did.
[0100]
In the obtained film, the thickness d in the thinnest region was about 35 μm. In addition, no abnormality such as cracks was observed in the antireflection film formed at a substrate temperature of 150 ° C. in the same configuration as in Example 1. However, the cured product had a refractive index of 1.49, and an insertion loss of 0.7 dB occurred due to reflection at the interface with the quartz glass substrate.
[0101]
In view of the above Examples and Comparative Examples, in the present invention, a preferable composition range of the molding resin composition is a composition comprising three compounds (A), (B) and (C) as shown in FIG. Stipulated. However, the compound (A) is a fluorinated epoxy compound represented by the aforementioned general formula (Formula 2), wherein R is CH ₂ (CF ₂ ) _n CH ₂ And n is an integer of 1 to 4. Compound (B) is a non-fluorinated epoxy compound, and compound (C) is a silane coupling agent.
[0102]
The weight ratio of the compounds (A), (B) and (C) in units of weight% is expressed as w _A , W _B , W _C , The points at which each of the compounds is 100% by weight are defined as vertices A, B, and C in the composition diagram of FIG. _A , W _B , W _C ) Represents the composition.
[0103]
In this composition diagram, composition C1 (Example 1) was at point (60, 40, 0), composition C2 (Example 2) was at point (50, 49, 1), and composition C3 (Example 3) was Point (60, 20, 20), composition C4 (Example 4) corresponds to point (50, 30, 20), and composition C5 (Example 5) corresponds to point (40, 45, 15).
The composition C6 (Comparative Example 1) had a point (0, 90, 10), the composition C7 (Comparative Example 2) had a point (20, 70, 10), and the composition C8 (Comparative Example 3) had a point (80). , 10, 10) and composition C9 (Comparative Example 4) correspond to point (0, 10, 90), respectively.
[0104]
From the above examples and comparative examples, the following points including the respective compositions of the examples, D (80, 20, 0), E (50, 20, 30), F (30, 40, 30), and G ( It can be said that a composition in a square DEFG surrounded by 30, 70, 0) is preferable, and D (80, 20, 0), H (60, 20, 20, 20), I (30, 50, 20), G ( Compositions within a square DHIG surrounded by 30, 70, 0) are more preferred. Furthermore, it is surrounded by K (70, 30, 0), L (70, 20, 10), M (40, 50, 10), and N (40, 60, 0) containing the compositions of Examples 1 and 2. Compositions within the square KLMN are most desirable. In this range, the refractive index of the cured resin composition is in the range of 1.45 to 1.48, which matches well with the refractive index of quartz glass.
[0105]
In the above example, the fluorinated epoxy compound of the compound (A) is shown as an example where n = 4, but n = 1 to 3 may be used. As the compound (B), among the alicyclic epoxy compounds, 3,4-epoxycyclohexylmethyl (3,4-epoxycyclohexane) carboxylate was used, but another alicyclic epoxy compound or an aromatic epoxy compound was used. You can also. The silane coupling agent is not limited to 3-glycidoxypropyltriethoxysilane, but may be another compound.
[0106]
In the above example, a quartz glass substrate was used as a base material, and the composition was adjusted so that the refractive index of the solid composition layer matched it. When the molding composition of the present invention is used, the refractive index after curing can be set within a certain range by adjusting the composition. Therefore, even when a substrate other than quartz glass is used, the refractive index can be adjusted while maintaining other performances.
[0107]
【The invention's effect】
As described above, the resin composition for molding of the present invention can provide a fine concave-convex structure with small heat shrinkage during molding and high dimensional accuracy. In addition, a dielectric multilayer film having high heat resistance and desired characteristics and durability can be formed on the cured composition layer. Further, it is possible to match the refractive index with the base material.
[Brief description of the drawings]
FIG. 1 is a view showing a manufacturing process of an optical element of the present invention.
FIG. 2 is a schematic diagram illustrating a configuration of a microlens array according to an embodiment of the present invention.
FIG. 3 is a view showing a composition range of a molding resin composition of the present invention.
[Explanation of symbols]
10 Mold
20 base material
22 Glass substrate
30 Composition for molding
32 solid composition layer
34 Resin cured film
40 Dielectric multilayer film
42 Adhesion strengthening layer
45 Anti-reflective coating
50 micro lens
100 optical elements
120 convex lens array

Claims (14)

After filling and pressing between the substrate and the mold, including a polymerizable organic group capable of obtaining a solid composition layer having a predetermined shape by polymerizing and curing by applying at least one of heat and ultraviolet rays In a molding resin composition having fluidity, the composition is mainly composed of the following three types of compounds (A), (B) and (C), and the compounds (A), (B) and (C) Where w _A , w _B , and w _C are weight ratios in units of weight% of the above, coordinates (w _A) in an equilateral triangle ABC having vertices A, B, and C at points where the respective compounds are 100 weight%. , _w B, expressed in _{w C), D (80,} 20, 0), E (50, 20, 30), F (30, 40, 30), surrounded by a G (30, 70, 0) A resin composition for molding, which is in a square DEFG.
However, the compound (A) is a fluorinated epoxy compound represented by the following general formula (Chemical Formula 1) (wherein R is CH ₂ (CF ₂ ) _n CH ₂ and n is a positive integer),

Compound (B) is a non-fluorinated epoxy compound, and compound (C) is a silane coupling agent. A square whose composition is surrounded by D (80, 20, 0), H (60, 20, 20), I (30, 50, 20), and G (30, 70, 0) using the coordinates. The molding resin composition according to claim 1, wherein the resin composition is in a DHIG. A rectangle whose composition is surrounded by K (70, 30, 0), L (70, 20, 10), M (40, 50, 10), and N (40, 60, 0) using the coordinates. The molding resin composition according to claim 2, which is in KLMN. The molding resin composition according to claim 1, wherein the molding resin composition contains 0.1 to 7% by weight of a polymerization initiator. The molding resin composition according to claim 1, wherein the molding resin composition contains 5% by weight or less of an antioxidant. The molding resin composition according to claim 5, wherein the molding resin composition contains 2% by weight or less of an antioxidant. The molding resin composition according to claim 1, wherein the solid composition layer obtained by curing the molding resin composition has a refractive index in the range of 1.45 to 1.48. The molding resin composition according to claim 1, wherein in the compound (A), n is 1, 2, 3 or 4. The molding resin composition according to claim 1, wherein the compound (B) is an alicyclic epoxy compound. The molding resin composition according to claim 1, wherein the compound (C) contains an epoxy group. The molding resin composition according to claim 1, wherein the compound (C) contains a γ epoxy group and a cyclohexyl group. The resin composition for molding according to any one of claims 1 to 11, which is filled and pressed between a substrate and a mold, and then subjected to polymerization and curing by applying at least one of heat and ultraviolet rays. An optical element comprising at least two dielectric films laminated on the surface of a solid composition layer having a predetermined shape. The optical element according to claim 12, wherein the base material is quartz glass. 14. The optical element according to claim 12, wherein a function of a transmission type diffraction grating, a Fresnel lens, or a micro lens array is provided by the predetermined surface shape.

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