JP3627304B2 - Ionizing radiation curable resin composition for optical articles, optical article and surface light source - Google Patents

Description

【００５６】
（式中、Ｒは水素またはメチル基、Ｒ_１は炭素数１〜５の炭化水素基を表わし、ｎは０〜３の整数を表わす。）
【００５７】
前記単官能（メタ）アクリレート（ｂ）と共に、これ以外の環状構造を有する単官能（メタ）アクリレートと併用することができる。その代表例のみを例示すると、イソボルニル（メタ）アクリレート、テトラヒドロフルフリル（メタ）アクリレート、グリシジルシクロカーボネート（メタ）アクリレート、フェノキシエチルアクリレート、シクロヘキシル（メタ）アクリレート、ジシクロペンタニル（メタ）アクリレート、ジシクロペンテニル（メタ）アクリレート、グリシジル（メタ）アクリレート、
【００５８】
フェノキシエチレングリコール（メタ）アクリレート、アダマンチル（メタ）アクリレート、モノホリン（メタ）アクリレート、２，４，６−トリブロモフェニルアクリレート、及び、２，４，６−トリブロモフェニルアルコキシアクリレートからなる群から選ばれる１種以上の単官能（メタ）アクリレート等が挙げられる。
【００５９】
また、これら以外の環状構造を有する単官能反応性希釈剤も本発明に使用する事が出来る。これら代表的なものとしては、スチレン、ビニ−ルピロリドン等を挙げることが出来る。
【００６０】
更に、水酸基、環状エーテル基、シクロカーボネート基、アミノ基、カルボキシル基、リン酸基、スルホン酸基等の酸基及びそのアルカリ金属塩等の極性官能基と環状構造とを有する単官能反応性希釈剤も好ましく用いられる。これらは、テトラヒドロフルフリル（メタ）アクリレート、グリシジルシクロカーボネート（メタ）アクリレート、フェノキシエチルアクリレート、２−ヒドロキシ−３−フェノキシ−プロピル（メタ）アクリレー等が挙げられる。
【００６１】
環状構造を有するエポキシ（メタ）アクリレート（ａ）と、環状構造を有する単官能（メタ）アクリレート（ｂ）と、必要に応じ添加する光開始剤（ｃ）との配合による本発明の樹脂組成物は、系の（メタ）アクリレート官能基濃度が０．２〜５．０ｍｍｏｌ／ｇであることが必要であるが、上述の環状構造を有するエポキシ（メタ）アクリレート（ａ）と、環状構造を有する単官能（メタ）アクリレート（ｂ）は各々単独で用いることもできるし、またそれらを必要に応じて２種類以上混合して用いることも出来る。（メタ）アクリレート官能基濃度が０．２ｍｍｏｌ／ｇより低いと、硬化性が低下し、また粘度が高くなり作業性が悪くなる。
【００６２】
また、（メタ）アクリレート官能基濃度が、５．０ｍｍｏｌ／ｇより高いと、硬化収縮により硬化シートがカールしてしまう。０．２〜５．０ｍｍｏｌ／ｇの（メタ）アクリレート官能基濃度により、硬化性が良好で、硬化時のカール等のフィルムの変形を防ぐことができ、かつ、良好な表面硬度が得ることが出来る。
【００６３】
本発明の光学物品の中でも、特にレンズ配列シートは、その変形により生じるカールが問題となる。カールは、作成された光学レンズシートをＡ４サイズに切り出し、水平面上にレンズ形成面を上にして静置し、レンズシートの端が水平面からカールした高さを測定することにより評価することができる。本発明の光学物品用電離放射線硬化型樹脂組成物を用いた硬化物のカールは、該評価方法で１ｍｍ以下であることが好ましい。
【００６４】
更に、レンズ配列シートの変形、即ち、カール性は、樹脂の硬化収縮率との相関性が深いことから、本発明に用いる光学物品用電離放射線硬化型樹脂組成物の硬化収縮率を求めることにより、カールを生じない樹脂組成を決定することができる。即ち、硬化収縮率は、硬化前の樹脂比重（ＤL）と硬化後の樹脂比重（ＤS）から、下記式１により算出でき、本発明で使用される光学物品用電離放射線硬化型樹脂組成物の硬化収縮率は、５．５％以下であることが好ましい。
硬化収縮率（％）＝〔（ＤS−ＤL）／ＤS〕×１００ （式１）
【００６５】
また、本発明の好ましい配合比率は、環状構造を有するエポキシ（メタ）アクリレート（ａ）が１０〜９０重量％であり、更に好ましくは、３０〜８５重量％である。更に、環状構造を有する単官能（メタ）アクリレート（ｂ）は、２０〜７０重量％である。単官能（メタ）アクリレート（ｂ）が７０重量％より多く存在する場合は、引っ張り試験で降伏点が出易く、硬化物が塑性変形を起こし易くなる。
【００６６】
本発明の光学物品用電離放射線硬化型樹脂組成物は、当然のことながら透明性に優れ、厚み０．４ｍｍのシートの４００〜９００ｎｍの波長領域の光の透過率が少なくとも８０％以上、多くは８５％以上であり、好ましくは透過率９０％以上である。
【００６７】
本発明の光学物品の中でも、特にレンズ配列シートは、外力による変形が復活しないことにより生じる置き痕が問題となる。レンズ配列シートは製造上、長尺帯状シートとして製造され、紙巻に巻取って製造、貯蔵されるが、この際にシート末端を粘着テープで紙巻に固定し、レンズ配列シートを紙巻に巻取る。この場合に、粘着テープ部分の盛り上がりが段差として突出し、レンズ配列シートに変形を生じる。この変形部分が永久変形となると所謂置き痕となる。
【００６８】
置き痕は、作成された光学レンズシートの一部である単位面積のみに任意の圧力を加え、任意の時間放置してその圧力を取り除いたとき、痕が確認できるか否かで評価することが可能である。具体的には、鉄製の平板上に、厚み７５μｍ、１インチ角の粘着テープを置き、その上に１０ｃｍ×１０ｃｍのレンズ配列シート６０枚を積層し、温度４０℃の条件で、５００ｇ／ｃｍ^２の荷重を３日間加え、荷重を除いた後に、透過光及び反射光による目視で判定する。
【００６９】
作成されたシートに置き痕が全く無いことが最も好ましいが、長尺ロール等に光学レンズシートを巻く場合には、通常、粘着テープから２１枚目以降のシートに置き痕の痕跡が確認されないものであれば、実用上問題がないレンズ配列シートを作成することができる。
【００７０】
本発明の光学物品は、製造時やディスプレー装着時に、硬化物表面に傷等の塗膜欠陥を生じる可能性があるが、光学物品として使用する為、これらの微小な傷は、致命的な欠陥となる。従って、本発明の樹脂組成物は、高い表面硬度が要求され、具体的には、鉛筆硬度として、ＪＩＳ Ｋ−５４００に準じて、Ｈ以上のものであることが好ましい。
【００７１】
また、必要に応じて、樹脂組成物中に、塗膜の改質や塗装適性、母型からの離型性を改善させるため、種々の添加剤として、紫外線吸収剤、光安定剤、酸化防止剤、レオロジーコントロール剤、シリコン添加剤、脱泡剤等を添加することも可能である。
【００７２】
本発明においては、硬化エネルギー線として電離放射線を用いる。電離放射線としては、可視光線、紫外線、Ｘ線等の電磁波、または電子線等の荷電粒子線が用いられるが、これらの内で実用上良く用いられるのは、可視光線、紫外線、または電子線である。特に可視光線または紫外線を用いて、本発明の樹脂調製物ならびに樹脂組成物を硬化させる場合には、波長が１，０００〜８，０００オングストロームなる紫外線または可視光線によって、解離し、ラジカルを発生するような光（重合）開始剤（ｃ）を使用すべきである。
【００７３】
かかる光（重合）開始剤としては、公知慣用のものが、いずれも併用できるが、そのうちでも代表的な例を挙げれば、例えば４−ジメチルアミノ安息香酸、４−ジメチルアミノ安息香酸エステル、アルコキシアセトフェノン、ベンジルジメチルケタール、ベンゾフェノンおよびベンゾフェノン誘導体、ベンゾイル安息香酸アルキル、ビス（４−ジアルキルアミノフェニル）ケトン、
【００７４】
ベンジルおよびベンジル誘導体、ベンゾインおよびベンゾイン誘導体、ベンゾインアルキルエーテル、２−ヒドロキシ−２−メチルプロピオフェノン、１−ヒドロキシシクロヘキシルフェニルケトン、チオキサントンおよびチオキサントン誘導体、２，４，６−トリメチルベンゾイルジフェノイルフォスフィンオキシド、
【００７５】
２−メチル−１−［４−（メチルチオ）フェニル］−２−モルホリノプロパン−１、２−ベンジル−２−ジメチルアミノ−１−（４−モルホリノフェニル）−ブタノン−１等が挙げられる。
【００７６】
これらのなかでは、１−ヒドロキシシクロヘキシルフェニルケトン、チオキサントンおよびチオキサントン誘導体、２，４，６−トリメチルベンゾイルジフェノイルフォスフィンオキシド、２−メチル−１−［４−（メチルチオ）フェニル］−２−モルホリノ−１−プロパノン、２−ベンジル−２−ジメチルアミノ−１−（４−モルホリノフェニル）−ブタン−１−オンの群から選ばれる１種または２種類以上の混合系が硬化性が高いので、特に好ましい。
【００７７】
光開始剤は、０．５〜１０重量％の範囲での添加が好適である。また、光（重合）開始剤に、公知慣用の光増感剤をも併用することができる。かかる光増感剤として特に代表的なもののみを例示するに留めれば、アミン類、尿素類、含硫黄化合物、含燐化合物、含塩素化合物またはニトリル類もしくは、その他の含窒素化合物等である。
【００７８】
本発明の光学物品用電離放射線硬化型樹脂組成物を用いた光学物品の製造では、紫外線等のエネルギ−線は、支持体となる透明基板面（シート状の透明樹脂層（Ｃ）を通して照射される場合が多い為、使用されうる光開始剤は、長波長領域に吸光能力を有する開始剤が好ましく、波長３６０〜４５０ｎｍの範囲、特に波長４００〜４４０ｎｍにおいて光開始能力を有する光開始剤の使用が望ましい。４５０ｎｍより大きい波長の光を吸収するものは、組成物の安定性が悪く、完全に遮光した環境での製造が必要となり、その取扱いが極めて困難となる。
【００７９】
こうした光の波長に吸光、開始能力を有する開始剤としては、２，４，６−トリメチルベンゾイルジフェノイルフォスフィンオキシド、チオキサンソンや置換チオキサンソン類、２−ベンジル−２−ジメチルアミノ−１−（４−モルホリノフェニル）−ブタノン−１、２−ベンジル−２−ジメチルアミノ−１−（４−モルフォリノフェニル）−ブタン−１−オン等が挙げられる。なお、電子線を用いる場合は、これら光開始剤や光増感剤は不要である。
【００８０】
本発明の光学物品の一つであるレンズ配列シートは、上述の電離放射線硬化型樹脂組成物層（Ａ）を所望の微細形状を有する母型の凹凸パターンに塗布しこれを充填させ、電離放射線硬化型樹脂層を電離放射線照射により硬化後、この母型より剥離し、母型の微細構造を複写したレンズ配列シートとして製造される。
【００８１】
その際、母型表面に塗布、充填された該組成物（Ａ）の一方の表面に更にシート状の透明樹脂層（Ｃ）を密着させた状態で電離放射線照射することが好ましい。該シート状の透明樹脂層（Ｃ）は最終製品に不要であれば、硬化工程後に剥離する。
【００８２】
接着剤層（Ｂ）は必ずしも必須のものではなく、電離放射線硬化型樹脂組成物層（Ａ）とシート状の透明樹脂層（Ｃ）の接着の程度、及び目的とする光学物品の要求性能により、必要に応じてシート状の透明樹脂層（Ｃ）と電離放射線硬化型樹脂組成物層（Ａ）との間に形成する。
【００８３】
ここで言うシート状の透明樹脂層（Ｃ）は、レンズ配列シートの物理的強度を付与する目的と、微細構造を有する母型の反対側の面の平滑性を得るために使用される。こうしたシ−ト状の透明樹脂層（Ｃ）を完成品のレンズ配列シートに使用しない場合にも、かかる平滑面を得るために、電離放射線硬化型樹脂組成物層（Ａ）を母型とシート状の透明樹脂層（Ｃ）との間に挟んだ状態で硬化させ、しかる後に、シート状の透明樹脂層（Ｃ）を剥離除去することが好ましい。
【００８４】
また、特に電離放射線として紫外線を用いる場合は、シート状の透明樹脂層（Ｃ）により空気中の酸素による硬化阻害を防止できることからも好ましい。更に、シート状の透明樹脂層（Ｃ）の電離放射線硬化型樹脂組成物層（Ａ）への接する側には、必要に応じ公知の離型処理を施しても良い。
【００８５】
一方、シート状の透明樹脂層（Ｃ）なしで、電離放射線硬化樹脂層の膜厚を厚くし、レンズ配列シートの強度を持たせることが考えられるが、電離放射線硬化樹脂層の膜厚が厚くなると、膜厚方向での硬化度合の不均一さや、硬化歪が生じ易くなる。それ故、シート状の透明樹脂層（Ｃ）と電離放射線硬化樹脂層（Ａ）を一体化することは、レンズ配列シートの製造、強度から好ましい方法である。
【００８６】
こうしたシート状の透明樹脂層（Ｃ）としては、物理的衝撃に対して、破断強度、引張強度等の機械的強度を有していて、均一な膜厚、平滑性、透明性、フレキシビリティ、耐久性を有していることが必要である。
【００８７】
この透明樹脂層（Ｃ）は、具体的にはシート状のものが好ましく、とりわけ、２０μｍ〜１ｍｍ程度のものが好ましく、加工性や、フィルム物性、透明性の観点から、特に５０〜１５０μｍが好適である。また、透明樹脂層（Ｃ）の表面は、層（Ｃ）と層（Ａ）とを接触させたまま最終製品とする場合は電離放射線硬化型樹脂層（Ａ）との密着性向上の為、コロナ放電処理、プラズマ処理、易接着プライマーコート等の易接着処理を行ったものでも良い。
【００８８】
具体的には、透明性の良い二軸延伸ポリエチレンテレフタレート等のポリエステルシート、ポリメチルメタクリレート等のアクリル系シート、ポリカーボネート系シート、塩化ビニル系シート、ポリスチレンシート等が使用できる。特に、耐久性の面から、ポリエチレンテレフタレ−ト系あるいは、ポリカ−ボネ−ト系のシ−トが好ましい。
【００８９】
本発明において、シート状の透明樹脂層（Ｃ）と電離放射線硬化型樹脂組成物層（Ａ）との積層体として、レンズ配列シートを構成する場合には、電離放射線硬化型樹脂層（Ａ）の耐久性はもとより、基材となるシート状の透明樹脂層（Ｃ）の耐久性、更には電離放射線硬化樹脂層（Ａ）と、シート状の透明樹脂層（Ｃ）の密着性も重要であり、この為、基材となるシート状の透明樹脂層（Ｃ）と、電離放射線硬化樹脂層（Ａ）の間に接着剤層（Ｂ）を設けることができる。
【００９０】
即ち、具体的には、接着層（Ｂ）が、セルロース樹脂（ｂ１）と、ポリイソシアネ−ト（ｂ２）とから成るもの、分子量３０００〜３００００のポリエステル樹脂（ｂ３）と、ポリイソシアネ−ト（ｂ２）とから成るもの、分子量３０００〜３００００のポリエステル樹脂（ｂ３）と、環状構造を有するエポキシ（メタ）アクリレートと、光開始剤から成り、かつ該エポキシ（メタ）アクリレ−トの含量が１０〜６０重量％であるものが挙げられる。
【００９１】
レンズ配列シートとしては、光学物品用電離放射線硬化型樹脂組成物から成る硬化物層（Ａ）と、セルロース樹脂（ｂ１）と、ポリイソシアネ−ト（ｂ２）から成る接着層（Ｂ）と、ポリエステルまたはポリカ−ボネ−ト樹脂から成るシート状の透明樹脂層（Ｃ）から成るレンズ配列シート、樹脂組成物から成る硬化物層（Ａ）と、分子量３０００〜３００００のポリエステル樹脂（ｂ３）と、ポリイソシアネ−ト（ｂ２）とから成る接着層（Ｂ）と、ポリエステルまたはポリカ−ボネ−ト樹脂から成るシート状の透明樹脂層（Ｃ）から成るレンズ配列シートや、
【００９２】
樹脂組成物から成る硬化物層（Ａ）と、分子量３０００〜３００００のポリエステル樹脂（ｂ３）と、環状構造を有するエポキシ（メタ）アクリレートと、光開始剤から成り、かつエポキシ（メタ）アクリレ−トの含量が１０〜６０重量％である樹脂組成物から成る接着層（Ｂ）と、ポリエステルまたはポリカ−ボネ−ト樹脂から成るシート状の透明樹脂層（Ｃ）から成るレンズ配列シートが挙げられる。
【００９３】
但し、基材シートとなる透明樹脂層（Ｃ）と、電離放射線硬化型樹脂層（Ａ）との密着性が十分であったり、或いは透明樹脂層（Ｃ）表面へのコロナ放電処理、プラズマ処理、易接着プライマーコート等の易接着処理等により、密着性が十分な場合は、接着剤層（Ｂ）は不要である。また密着性をより強固にする目的で、易接着処理と接着剤層（Ｂ）とを併用することもできる。
【００９４】
接着剤層（Ｂ）としては、支持体となる透明樹脂層（Ｃ）と微細構造を形成する電離放射線硬化型樹脂層（Ａ）との両方に優れた接着能力を有するものから選定しなければならない。本発明の接着剤層（Ｂ）としては、熱可塑性樹脂とポリイソシアネート（ｂ２）、あるいは熱可塑性樹脂とアクリレート化合物の樹脂組成物、あるいはポリイソシアネ−ト（ｂ２）とポリエステル（ｂ３）からなる樹脂組成物が、優れた密着性を有し、特に好ましく用いられる。
【００９５】
ここで言う熱可塑性樹脂としては、公知慣用のものが使用出来るが、好ましくは、各種のセルロースエステルやセルロースエーテル等のセルロース樹脂（ｂ１）、各種（メタ）アクリル酸エステル重合体であるアクリルラッカー等のアクリル系樹脂、高分子量オイルフリーポリエステル等のポリエステル系樹脂、ポリカーボネート系樹脂、ポリエステルやポリエーテル系のポリウレタン等が挙げられる。特に、これらの内で、セルロース樹脂（ｂ１）、ポリエステル樹脂（ｂ３）が好ましい。
【００９６】
ここで言うセルロースエステル樹脂とは、セルロース中の水酸基を、酸類で部分的にエステル化したものであり、硝酸、硫酸、酢酸、プロピオン酸、酪酸、その他の高級脂肪酸等の一つ以上の酸とのエステル化により得られるものである。特に、酢酸、プロピオン酸、酪酸によりエステル化されたセルロースエステル樹脂が好ましく用いられる。セルロースエーテル樹脂もセルロースエステル樹脂と同様に用いることができる。また、エステル及びエーテル結合を有するセルロース樹脂も好ましく用いられる。
【００９７】
ここで言うポリエステル樹脂（ｂ３）としては、飽和、不飽和のポリオールと多塩基酸、あるいは低級アルキルエステルとのエステル化反応やエステル交換反応によって得られる公知慣用のものであり、分子量は３，０００〜３０，０００である。こうしたポリオール原料としては、公知慣用のものが使用できるが、そのうち代表例を挙げれば、エチレングリコール、１，３−プロピレングリコール、１，２−プロピレングリコール、ジエチレングリコール、ジプロピレングリコール、ネオペンチルグリコール、
【００９８】
１，３−ブタンジオール、１，４−ブタンジオール、１，６−ヘキサンジオール、１，９−ノナンジオール、１，１０−デカンジオール、２，２，４−トリメチル−１，３−ペンタンジオール、３−メチル−１，５−ペンタンジオール、ジクロロネオペンチルグリコール、ジブロモネオペンチルグリコール、ヒドロキシピバリン酸ネオペンチルグリコールエステル、シクロヘキサンジメチロール、
【００９９】
１，４−シクロヘキサンジオール、トリメチロールエタン、トリメチロールプロパン、グリセリン、３−メチルペンタン−１，３，５−トリオール、ペンタエリスリトール、ジペンンタエリスリトール、トリペンタエリスリトール、スピログリコール、トリシクロデカンジメチロール、水添ビスフェノールＡ等である。
【０１００】
更に、多塩基酸化合物としては、公知慣用の各種のカルボン酸、またはそれらの酸無水物、及びこれらカルボン酸化合物と低級アルキルアルコールのエステル化物が使用できるが、それらのうちでも特に代表的なもののみを例示するにとどめれば、マレイン酸、フマル酸、イタコン酸、シトラコン酸、テトラヒドロフタル酸、ヘット酸、ハイミック酸、クロレンディック酸、ダイマー酸、アジピン酸、こはく酸、アルケニルこはく酸、セバチン酸、アゼライン酸、
【０１０１】
２，２，４−トリメチルアジピン酸、１，４−シクロヘキサンジカルボン酸、テレフタル酸、２−ナトリウムスルホテレフタル酸、２−カリウムスルホテレフタル酸、イソフタル酸、５−ナトリウムスルホイソフタル酸、５−カリウムスルホイソフタル酸、またはジメチル−ないしはジエチルエステルの如き、５−ナトリウム−スルホイソフタル酸のジ−低級アルキルエステル類、あるいは、オルソフタル酸、４−スルホフタル酸、１，１０−デカメチレンジカルボン酸、
【０１０２】
ムコン酸、しゅう酸、マロン酸、グルタン酸、トリメリット酸、ヘキサヒドロフタル酸、テトラブロムフタル酸、メチルシクロヘキセントリカルボン酸もしくはピロメリット酸、またはこれらの酸無水物、または、メタノール、エタノール等のアルコールエステル化合物などが挙げられる。
【０１０３】
また、ここでいう（メタ）アクリル酸エステルとしては、公知慣用のもが使用できるが、より具体的には、メチル（メタ）アクリレート、エチル（メタ）アクリレート等のアルキル（メタ）アクリレートや、環状構造を有する（メタ）アクリレート、ポリオキシアルキレン（メタ）アクリレート等挙げることが出来る。
【０１０４】
更に、環状エステル化合物としては、γ−ブチロラクトン、γ−バレロラクトン、δ−バレロラクトン、ε−カプロラクトン、Ｄ−グルコノ−１，４−ラクトン、１，１０−フェナントレンカルボラクトン、４−ペンテン−５−オリド、１２−ドデカノリド等のラクトン類が挙げられる。
【０１０５】
また、接着層に好ましく使用し得るアクリレート化合物としては、通常、反応性希釈剤として用いられるものや、各種アクリレートオリゴマー、アクリレートポリマーが使用でき、これらアクリレート化合物としては、エポキシアクリレ−ト、ウレタンアクリレ−ト、ポリエステルアクリレート、ポリエーテルアクリレート等単独または２種類以上を併用して使用できる。
【０１０６】
この中でも、微細パターンを有する電離放射線硬化型樹脂層との密着性の観点から、エポキシアクリレート化合物が特に好ましい。ここで使用されるエポキシアクリレートとしては、上述の電離放射線硬化型樹脂組成物で例示したものが使用でき、またこれらアクリレート化合物は、接着層樹脂中の１０〜６０重量％であることが好適である。
【０１０７】
アクリレ−ト化合物が１０重量％未満の場合は、接着層の上層となる電離放射線硬化樹脂層との密着性が低下したり、耐水試験にて、白化等の現象が見られたりする。また、アクリレート化合物の量が６０重量％より多い場合には、基材との密着性が減少する弊害を生じ易い。
【０１０８】
また、ポリエステルやポリエーテル系のポリウレタン等としては、上述のポリエステルの分子量が５００〜４０００程度のポリエステルポリオールやポリエチレングリコール、ポリプロピレングリコール、ポリテトラメチレングリコール等のポリアルキレンオキサイドとポリイソシアネートとの反応で得られるポリウレタン樹脂が使用できる。
【０１０９】
ここで言うポリイソシアネートとしては、単独で使用しても、あるいは、イソシアヌレート化せしめた形のポリイソシアネートとイソシアネート化合物とを併用してもよいことは、勿論であり、公知慣用の二官能以上のイソシアネートをいずれも用いることができるが、これらの代表的なもののみを例示するにとどめれば、トルレンジイソシアネート、ジフェニルメタンジイソシアネート、キシレンジイソシアネート、ジシクロヘキシルメタンジイソシアネートもしくはイソホロンジイソシアネート、水添キシリレンジイソシアネートの如き、各種の脂環式ジイソシアネート化合物、
【０１１０】
またはヘキサメチレンジイソシアネートもしくはリジンジイソシアネートの如き、各種の脂肪族ジイソシアネート化合物など各種の化合物などが挙げられる。また、上記イソシアネ−トモノマ−をビュレット、アロハネ−ト、イソシアヌレ−ト化せしめたイソシアネ−ト多量体、更にポリオ−ルとの反応により得られるポリイソシアネ−トも使用できる。これらは単独でも、また併用して使用しても良い。これらの内でもイソシアネ−ト基を分子中に３個以上有するポリイソシアネ−ト化合物が好ましく、特にヘキサメチレンジイソシアネートから誘導されるポリイソシアネ−トが好ましい。
【０１１１】
熱可塑性樹脂とポリイソシアネ−トの割合は、熱可塑性樹脂の水酸基当量とポリイソシアネ−トのイソシアネ−ト当量の比率、ＯＨ当量／ＮＣＯ当量比率が、０．１〜５の範囲、好ましくは０．１〜１の範囲で配合することが接着性の信頼性の上で望ましい。また接着剤層（Ｂ）の膜厚としては、０．２〜１０μｍの範囲が適切である。
【０１１２】
シート状の透明樹脂層（Ｃ）に、接着剤層（Ｂ）を塗装し、必要ならセッティング時間を設けるか、あるいは、温度をかけて溶剤等を揮発させる。この後、電離放射線硬化型樹脂層（Ａ）を塗装し、所望の微細形状を有する母型を密着させ、この状態で電離放射線硬化型樹脂層を電離放射線硬化させることにより、シートと電離放射線硬化層の密着を得ることが出来る。
【０１１３】
また、接着剤層（Ｂ）、特に熱可塑性樹脂とアクリレート化合物の樹脂組成物系に、光（重合）開始剤を添加することが 接着層の反応性を上げる観点から好ましく、かかる開始剤としては、前述の光開始剤が使用できる。
【０１１４】
本発明の電離放射線硬化型樹脂組成物を用いた光学物品の一つであるレンズ配列シートの製造方法としては、公知の各種の製法が適用でき、特に限定されないが、好ましい製法としては、例えば米国特許第３６８９３４６号公報、米国特許４５７６８５０号公報、特公昭６３−５００６６号公報、特開平５−１６９０１５号公報等に開示されているような製法を用いる。次に、図４を用いてレンズ配列シートの製造方法の概要を説明する。
【０１１５】
図４において、１は所望の凹凸が形成されたロール凹版、２はそのロール凹版１の凹部、３は未硬化の電離放射線硬化性樹脂液、３ａは硬化した電離放射線硬化性樹脂、４は必要に応じて接着剤層（Ｂ）を付した透明な基材シート（Ｃ）、５はロール凹版１を押圧する押圧ロール、６及び８は送りロール、７は電離放射線照射装置、９は目的とするレンズ配列シート、１０はＴダイ型ノズル、１１は乾燥装置、１２は液溜である。
【０１１６】
電離放射線硬化型樹脂３をロール凹版１の凹部２に充填する方法としては、図４に示した様に、ロール凹版１の表面に、予め電離放射線硬化型樹脂液３を所定量塗工しておいて、基材シート４をロール凹版１へ供給したときに、押圧ロール５の基材背面側からの押圧により、基材シート４を介して、塗工されている電離放射線硬化型樹脂液３を凹部２内に配分充填させる。
【０１１７】
この場合に、溶剤タイプの硬化性樹脂が使用でき、乾燥装置１１により溶剤を揮発除去できる。電離放射線照射装置７は、図４に示したように１個でもよいが、複数個の硬化装置を設け、ロール凹版１内の樹脂液３を多段階に硬化させるようにしてもよい。このようにすれば、基材シート４の走行速度を速くしても十分な照射量が得られ、また、徐々に硬化することにより、樹脂液３の硬化歪、基材シート４のカールや歪を低減するために好ましい。
【０１１８】
次いで、基材シート４がロール凹版１に接している間（具体的には、図中の押圧ロール５と送りロール６との間に位置している時期）に、電離放射線照射装置７により電離放射線硬化型樹脂３を硬化させる。なお、電離放射線照射装置７により電離放射線を照射する場合には、基材シート４側から行われるが、ロール凹版を石英、ガラス等の電離放射線の透過性がよい材質により形成して、ロール凹版１の内部側より照射することもできる（具体的にはロール中空内に設置した照射装置により行なう）。また、基材シート側と凹版内部側と両面より照射してもよい。
【０１１９】
電離放射線照射装置７により、ロール凹版１の凹部２内にある電離放射線硬化型樹脂３を基材シート４に硬化密着させる。電離放射線照射装置７を通過した後、基材シート４をロール凹版１から剥離する。これにより、硬化した電離放射線硬化型樹脂液３ａが基材シート４と一体となって、凹部２から脱離され、凹凸表面を有するレンズ配列シート９が得られる。
【０１２０】
なお、上述の様な製造方法において、透明な基材シート４としては、例えば、ポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリエチレンナフタレート、等のポリエステル樹脂、ポリメチルメタクリレート等のアクリル樹脂、ポリカーボネート樹脂、ポリスチレン樹脂等の熱可塑性樹脂等からなるシートが使用できる。厚みは、装置取扱い等の作業性の面から決められるが、通常１０〜１０００μｍ程度である。
【０１２１】
最終製品の段階で、もし基材シートが不要であれば、該基材シートのレンズ配列を有する側の面に予め電離放射線硬化性樹脂の硬化物に対して離型性を付与する処理（シリコーン樹脂、メラミン樹脂等の離型性樹脂層を塗工する等）を施しておき、上述の製法が完了した後、該基材シートをレンズ配列シートから剥離除去すればよい。
【０１２２】
電離放射線照射装置の電離放射線とは、電磁波または荷電粒子線のうち、分子を重合、架橋しうるエネルギー量子を有するものを意味し、通常、紫外線、電子線等が用いられ、紫外線の場合には、超高圧水銀灯、高圧水銀灯、低圧水銀灯、カーボンアーク、ブラックライトランプ、メタルハライドランプ等の光源を用いることができる。紫外線波長は、通常１９００〜３８００オングストロームの波長域が主として用いられる。
【０１２３】
また、電子線の場合には、コックロフトワルトン型、バンデグラフ型、共振変圧器型絶縁コア変圧器型、あるいは、直線型、ダイナミトロン型、高周波型等の各種電子線加速器等の照射源を備えた装置を用いることができ、１００〜１０００ＫｅＶ、好ましくは１００〜３００ＫｅＶのエネルギーを持つ電子を照射する。照射線量としては、通常０．５〜３０Ｍｒａｄ程度が好ましい。
【０１２４】
図４中の溶剤乾燥装置１１は、樹脂の溶剤を揮発させるための装置である。溶剤乾燥装置１１としては、温風、赤外線ヒーター等を用いることができる。なお、無溶剤型の電離放射線硬化型樹脂を用いるときには、乾燥装置１１は不要である。
【０１２５】
次に、本発明の光学物品の具体例として、電離放射線硬化性樹脂の硬化物からなる単位レンズを１次元又は２次元方向に配列したレンズ配列を形成してなるレンズ配列シートの代表的な形状を示す斜視図を、図５〜図９に示す。
【０１２６】
図５は三角柱プリズム（レンズ）を単位レンズ４１として用い、平面上に該単位レンズを、その稜線方向が互いに平行になるように隣接させて一次元方向（稜線と直行する方向）に多数配列してレンズ配列シート９とした、所謂３角プリズム線型配列シートである。頂角βは代表的には６０゜〜１２０゜程度であり、繰り返し周期Ｐは代表的には２０〜５００μｍである。
【０１２７】
図６は半円柱又は半楕円柱形の凸レンズを単位レンズ４１として用い、該単位レンズを、その稜線方向が互いに平行になる様に隣接させて一次元方向（稜線と直行する方向）に多数配列してレンズ配列シート９としたもの、所謂レンチキュラーレンズである。図７は図６に於いて、単位レンズを凸レンズから凹レンズに置き換えたもので、凹レンズ形レンチキュラーレンズとも呼ぶべきものである。
【０１２８】
図８は半球又は半回転楕円体を単位レンズとし、該単位レンズを２次元方向に多数配列してレンズ配列シート９としたもの、所謂、蠅の目レンズである。図９は４角錐を単位レンズとし、該単位レンズを２次元方向に多数配列してレンズ配列シート９としたものである。
【０１２９】
但し、図５〜図９はレンズ配列シートの一部の例に過ぎず、本発明のレンズ配列シートはこれらに限定されるものでは無い。例えば、以下の様なものも本発明の光学物品に包含される。
（１）フレネルレンズの様に個々の単位レンズの形状が互いに異なったもの、或いは非周期的に単位レンズを配列したもの（一方、図５〜図９のレンズは同一形状の単位レンズを多数配列した周期配列を有するものである）でも良い。
【０１３０】
（２）単位レンズは凸レンズ、凹レンズのいずれでも良く、凹レンズと凸レンズの組見合わせ配列でも良い。
（３）更に、本発明に於けるレンズの概念は透過光を屈折或いは内面での反射によって光に集光、偏向、拡散等の変調、制御を加える素子のことを総称するものであり、プリズム、回折格子、ホログラム等も包含する。
【０１３１】
（４）本発明のレンズ配列シートは、図５〜図９の様に１枚のみで使用しても良いし、必要とあれば図１０の様に２枚以上積層して使用しても良い。例えば図１０の様に２枚のレンズ配列シートを、その稜線が互いに直行するように積層すると、透過光の制御、変調をＸ方向及びＹ方向の２方向とも行うことが出来る。
【０１３２】
（５）本発明のレンズ配列シート９は、図５、図７、図８、及び図９の様に電離放射線硬化性樹脂組成物の硬化物からなる単一層の構成でも良いし、或いは図６の様に透明な基材シート（板、フィルムも含む）４の表面にレンズ配列（４１）を形成した２層構成のものでも良い。
【０１３３】
（６）本発明のレンズ配列シートは図５〜図９の様にシートの片面にレンズ配列を有するものの他、シートの両面にレンズ配列を有するものであっても良い。
【０１３４】
レンズ配列シートの微細形状を有する母型としては、フレネルレンズやレンチキュラーレンズ、フライアイ（蠅目）レンズを与える型、又はその変形としては、例えば、多角錐、円錐台、または多角錐台の同一形状かつ同一体種の形状を平面上に等方的に多数配列したものを形成することができる。ここで、角錐または角錐台として、正三角錐（または錐台）、正四角錐（または錐台）、正六角錐（または錐台）を用いると、平面内に隙間なく配列でき、かつ形状も等方的であり、水平および垂直方向とも同等な半値角を持たせることができ、場所による変動もなく好ましい。
【０１３５】
または、複数個の連続した三面角体または、４面角体のプリズム要素の配列等の光学部の形状と同形状で逆凹凸の形状を有する面である金属製、あるいは合成樹脂製の型を用いることが可能である。またこうした母型は、平面上に微細形状を有しても、円筒形状のものの表面に有しても製造可能である。
【０１３６】
次に、本発明の面光源について説明する。
本発明の面光源は、少なくとも、透光性平板からなる導光体と、該導光体の側端面のうちの１面以上の面に隣接して設けられた光源ユニットと、前記導光体裏面に設けられた光反射層と、前記導光体表面の光放出面上に積層してなる１枚又は２枚の本発明の光学物品（レンズ配列シート）とから構成し、一般にエッジライト型面光源と呼ばれるものが、その代表例である。
【０１３７】
図１１に本発明の面光源の一例の斜視図を示す。少なくとも、導光体５１とその側端面の少なくとも一箇所以上に隣接して設置された線状または点状の光源５２と、導光体５１に接する光反射層５３と、本発明の光学物品（レンズ配列シート）９とから構成される。また、通常は、さらに光源５２の周囲には、内面が反射面であるランプハウス５４を備える。
【０１３８】
通常、導光体５１は、アクリル樹脂、ポリカーボネート樹脂、ガラス等から成る１〜１００ｍｍ程度の透明板を用いる。透明板は全面均一の厚みでも良いが、光源からの距離が離れるほど、厚みを薄くすると、出力光の輝度が光源からの距離によらず均一になり好ましい。光源５２には、線光源としては冷陰極管等の蛍光灯を、点光源としては、白熱電球、発光ダイオード等を用いる。
【０１３９】
光反射層５３は、光を拡散反射するために、一般的には白色インキの印刷等により光拡散反射性の点状パターンを形成し、その更に裏面に金属膜を蒸着やメッキして形成する。また通常は、光源からの距離が遠くなるほど、光拡散反射性の点状パターンの面積率を増加させることにより、光射出面からでる光量の均一化を行う。また、導光体５１とレンズ配列シート９との間に、光拡散透明性シートを配列し、光を均一に拡散させ、且つ光反射層５３の光拡散ドットパターンを見えなくすることもある。
【０１４０】
レンズ配列シートを面光源に実装する場合、レンズのある側が導光板側でも、或いは導光板と反対側（出光面側）のいずれの側を向いた構成も可能である。またレンズ配列シートの枚数は、一枚でも良いが、柱状レンズの場合、２方向（上下方向と左右方向）の光拡散角を制御するためには、図１０の様に２枚のレンズ配列シートを、単位レンズの稜線が交差（同図では直交）するように積層しても良い。
【０１４１】
この場合、レンズ配列を有する面（以下、レンズ面）の向きは、２枚とも同一の向きにすると光透過性が高く、また、下側のレンズ配列シートのレンズ面と、上側レンズ配列シートの裏面の微小突起とのモアレ縞を防止できる為に好ましい。また、２枚のレンズ配列シートのレンズ面を、対向させて向き合うようにしてもよい。
【０１４２】
本発明のエッジライト型面光源は各種用途、例えば、透過型の液晶表示素子や照明付き広告板、看板、交通標識、写真の陰画、陽画等観察する為のライトテーブル、室内の照明等に用いることができる。図１２は、図１１の面光源１００上に透過型液晶表示板６０を配列して液晶表示装置（ＬＣＤ）２００とした例である。
【０１４３】
面光源の好ましい性能としては、例えば、特開平５−１６９０１５号公報、その他の公知資料に記載されているが、表示画面の放線方向の明るさ（法線輝度）が、通常、１０００ｃｄ／ｃｍ^２以上であるが、面光源は、通常、明るいものが好ましく、特に法線輝度の上限を定める必要はない。
【０１４４】
また、テレビ、ワードプロセッサー、液晶表示板等では、水平方向の視野が必要とされる為、放線方向からの光の拡散による輝度の低下が少ない、即ち、法線方向の輝度が広い範囲で減少しないことが好ましく、法線輝度の半分の輝度となる角度（半値角）が、広いことが好ましい。通常、これら用途に用いられる面光源の半値角は３０〜９０度であり、好ましくは４５〜９０度である。
【０１４５】
【実施例】
次に、実施例、比較例により、本発明をより具体的に説明するが、本発明は、元より、これらに限定されるべきものではない。尚、例中の部及び％は、特に記載のない限り、すべて重量基準である。
【０１４６】
（比較合成例１）
温度計、攪拌器、及びコンデンサ−を備えたフラスコに、ジフェニルメタンジイソシアネートの５２４部を仕込み攪拌しながら６０℃に昇温し、ε−カプロラクトンと１，６−ヘキサンジオールの開環反応物（ＯＨ価＝２１５ＫＯＨ−ｍｇ／ｇ）５２０部を発熱に注意しながら１時間かけて滴下反応した。反応を１０時間行い、その後、ヒドロキシエチルアクリレートの２３２部を添加し、更に１０時間反応を行った。赤外吸収スペクトルによりイソシアネート基の吸収が消滅したことを確認して比較対照例のハードセグメントとソフトセグメントを有するウレタンアクリレート（ＲＳＨ−１）を得た。
【０１４７】
（比較合成例２）
温度計、攪拌器、及びコンデンサ−を備えたフラスコに、イソホロンジイソシアネートの４４４部を仕込み攪拌しながら６０℃に昇温し、１，６−ヘキサンジオールとアジピン酸のポリエステルジオール（ＯＨ価＝５１ＫＯＨ−ｍｇ／ｇ）２２００部を発熱に注意しながら１時間かけて滴下反応した。反応を１０時間行い、その後、ヒドロキシエチルアクリレートの２３２部を添加し、更に１０時間反応を行った。
【０１４８】
赤外吸収スペクトルによりイソシアネート基の吸収が消滅したことを確認し、更に、トリプロピレングリコールジアクリレートを１９１７部を加え、完全に溶解して比較対照例のハードセグメントとソフトセグメントを有するウレタンアクリレート（ＲＳＨ−２）を得た。
【０１４９】
（実施例１〜４）
表１に示す配合により光学シート用電離放射線硬化型樹脂組成物（Ａ）を調製した。
【０１５０】
次に、図４に示す装置を用いて、５０μｍピッチで連続して並ぶ正４面体を複数二次元的に配列した形状を有する逆反射性レンズと同形状逆凹凸を表面に持つ金属製ロール凹版を軸の回りに回転しつつ、Ｔダイ型ノズルから電離放射線硬化型樹脂組成物（Ａ）を該ロール表面に塗布し、該ロール凹版の周速度と同期する速度で、シート状の透明樹脂層（Ｃ）（透明ＰＥＴフィルム：片面コロナ放電処理）を走行させつつ、該透明ＰＥＴフィルムのコロナ放電処理面と該ロール凹版表面とを、電離放射線硬化型樹脂組成物（Ａ）を間に介して密着させ、そのままＰＥＴフィルム側から、高圧水銀ランプ（１６０Ｗ／ｃｍ）２灯を１０ｃｍの位置より、照射し、樹脂層を硬化させると同時にＰＥＴフィルムに接着させた。
【０１５１】
この時ＰＥＴフィルム表面に照射される紫外線の照射量は５００ｍｊ／ｃｍ^２であった。硬化後、ＰＥＴフィルムを電離放射線硬化樹脂層と共に、ロール凹版から剥離し、欲するロール凹版の形状を転写した光学シートの連続シートを製造した。光学シート、及び硬化樹脂の物性評価として、置き痕、カ−ル、付着等の各試験を行った。
【０１５２】
また、調製された実施例の樹脂組成物を、それぞれ清浄で平滑なガラス板上に６０〜７０μｍの厚さに塗布し、高圧水銀灯（１６０Ｗ／ｃｍ）により紫外線を５００ｍｊ／ｃｍ^２照射し、硬化テストピースを作製した。この硬化物については、引張試験と硬化性等の評価を行った。これらの結果を表３に示す。
【０１５３】
（比較例１及び２）
表２の配合により、比較対照用光学シート用電離放射線硬化型樹脂組成物を調製した。これについて実施例１〜４と同様に物性試験用硬化物及びレンズ配列シートを作製した。実施例１〜４と同様に物性試験用硬化物の比較評価を行った結果を表３に示す。また、レンズ配列シートの評価結果を表５に示す。
【０１５４】
（実施例５及び６）
シート状の透明樹脂層（Ｃ）として、透明なＰＥＴフィルム（膜厚１００μｍ）を用い、この上に接着層（Ｂ）をロールコーターにて、乾燥膜厚約１μｍになるよう塗布した。なおこの時、接着層組成物中に含有される溶剤を８０℃、３０秒間の加熱処理により乾燥させた。接着層（Ｂ）の樹脂組成を下記に示す。
【０１５５】
実施例５では、紫外線硬化型樹脂層として実施例１の組成のものを、また、実施例６では、紫外線硬化型樹脂層として実施例３のものをそれぞれ使用し、実施例１〜４記載の方法でのシート状の透明樹脂層（Ｃ）（透明ＰＥＴフィルム：片面コロナ放電処理）の代わりに接着層（Ｂ）を塗布したペットフィルムを使用した以外は全く同様にして、レンズ配列シートを製造した。尚、紫外線硬化樹脂層は、接着剤層（Ｂ）の上になるよう製造した。これらレンズ配列シートの評価結果を表５に示す。
【０１５６】
（実施例５の接着層（Ｂ）の樹脂組成）
高分子量オイルフリーポリエステル樹脂（テレフタル酸、イソフタル酸、アジピン酸、エチレングルコール、１，６−ヘキサンジオ−ル、ネオペンチルグリコ−ルの縮合体、分子量約５０００）１０部、ビスフェノールＡエポキシアクリレート２部、トルエン４部、酢酸ブチル４部で、合計２０部とした。
【０１５７】
（実施例６の接着層（Ｂ）の樹脂組成）
セルロースアセテートブチレート樹脂（ブチル化度３７％、アセチル化度１３％、残存水酸基２％）１５部、トルエン４０部、メチルエチルケトン４０部、ヘキサメチレンジイソシアネートのトリメチロールプロパンアダクト型ポリイソシアネ−ト（ＮＣＯ％＝１６．７％）５部で、合計１００部とした。
【０１５８】
（測定・評価方法）
以下に測定・評価方法を記載する。
（１）粘度
Ｅ型回転粘度計、２５℃での粘度測定（ｃｐｓ）を行った。
【０１５９】
（２）屈折率
液状サンプルと硬化サンプルを測定した。液状サンプルは、Ａｂｂｅ屈折計のプリズムに直接塗布し、２５℃にて測定を行った。また、ガラス板上に、硬化させた樹脂層をガラス板から剥し、試料とした。試料をプリズムに密着させる中間液として、１−ブロモナフタレンを用い、Ａｂｂｅ屈折計にて、試料温度２５℃にて測定した。測定結果を表６に示す。
【０１６０】
（３）引張試験（破断強度、破断伸度、引張弾性率、σ２／σ１、及び、ＳＳパターン）
上記硬化物のシートを株式会社ダンベル社製スーパーダンベル（ＪＩＳ ７１１３ ２号ダンベル）を用いて打ち抜き、測定シートとし、破断強度、破断伸度、引張弾性率の測定を行った。但し、測定時、チャックでの測定シートの滑りを防止する目的で、標線間（２５ｍｍ）の外側の左右上下４箇所を厚さ０．３ｍｍ、縦横２０ｍｍの鉄板および接着剤（東亜合成化学社製アロンアルファ）を用いて固定し、掴み部とした。
【０１６１】
試験機は、東洋ボールドウィン社製テンシロンを使用し、変形速度を１．０ｍｍ／ｍｉｎとし、２５℃、相対湿度５０％の雰囲気下にて測定を行った。
破断強度、破断伸びおよび引張弾性率：剛性率と同様に引張試験を行い、測定シートが破断した時点の応力、伸びを測定しそれぞれ破断強度および破断伸びとした。また、引張弾性率は、引張変形開始点からＳ−Ｓカ−ブ（応力−歪曲線）の接線を引き、その傾きから算出した。但し、測定回数は５回とし、その平均値を評価結果として表に示した。
【０１６２】
σ２／σ１（弾性評価）：上述で得られた図３に示されるようなパターンのＳ−Ｓ曲線から、σ２およびσ１を読みとりσ２／σ１を算出した。
Ｓ−Ｓ曲線のパターン評価：同様に各々のＳ−Ｓカ−ブより、図１に示すような降伏点のないパターンをＡ、図２に示すような降伏点を有するパターンをＢとして表中に記載した。
【０１６３】
（４）置き痕
平滑な鉄板上の中央に、厚み７５μｍ、１インチ角のＰＥＴ粘着テープを置き、その上に、作成されたレンズ配列シートを１０ｃｍ×１０ｃｍに切り出したもの６０枚を紫外線硬化樹脂層が上部になるように重ね合わせた。更に、その上から５００ｇ／ｃｍ^２の荷重を加えた。温度４０℃で、荷重を加えたまま、３日間放置後、荷重をとり除き、各レンズ配列シートを蛍光灯に透かし、又は反射光により、目視により置き痕の有無について判定し、置き痕が確認できるシートが粘着テープから何枚目であるのかを確認した。
【０１６４】
○：粘着テープから２１枚目以降のシートに置き痕の痕跡が確認されない。
×：粘着テープから２１枚目以降のシートにも置き痕が確認できる。
【０１６５】
（５）光線透過率
厚み０．４ｍｍのテストピースを作製し、４００〜９００ｎｍの波長領域の光透過率を測定し、全領域で９０％以上の透過率を示すものを○（合格）とし、透過率がそれ以下のものを×（不合格）とした。
【０１６６】
（６）鉛筆硬度
ＪＩＳ Ｋ−５４００に準拠して測定を行った。Ｈ以上を○（合格）とし、Ｆ以下を×（不合格）とした。
【０１６７】
（７）硬化収縮率
実施例、比較例の電離放射線硬化型樹脂組成物をそれぞれ内径３０ｍｍ、高さ１０ｍｍのステンレス製パンに、約５ｍｍの高さまで入れ、高圧水銀灯（８０Ｗ／ｃｍ）のコンベア式紫外線照射装置を用い、空気雰囲気下で１０００ｍｊ／ｃｍ^２の紫外線を照射して比重測定用の硬化物を作成した。
【０１６８】
これをＪＩＳ Ｋ−７１１２ Ｂ法に準拠し、２３±２℃で硬化物の比重（ＤＳ）を測定した。但し、浸せき液には、蒸留水を使用し、２３±２℃で樹脂組成物の比重（ＤＬ）を測定し、次式により硬化収縮率を算出した。測定結果は２回の測定結果の平均値を算出し、５．５％以下の時を○（合格）とし、それ以上の時を×（不合格）とした。
硬化収縮率（％）＝〔（ＤＳ−ＤＬ）／ＤＳ〕×１００
【０１６９】
（８）カール性
作成されたレンズ配列シートをＡ４サイズに切り出し、水平面上にシート形成面を上にして静置し、光学シートの端が水平面から自然にカールした高さ（ｍｍ）を測定し、カールした高さが１ｍｍ以下の時を○（合格）とし、それ以上の時を×（不合格）とした。
【０１７０】
（９）初期密着性
基材の透明ＰＥＴと光学シート層を形成する電離放射線硬化樹脂層との密着性をＪＩＳ Ｋ−５４００に準拠して測定した。９５／１００以上の升目が残存する時を○（合格）とし、それ以下の時を×（不合格）とした。
【０１７１】
（１０）硬化性
１６０Ｗ／ｃｍの高圧水銀灯で、１５ｃｍのランプ高さ、ラインスピ−ド１０ｍ／ｍｉｎで照射したとき、表面タックフリ−になるまでの照射回数を測定した。照射回数が少ない方が硬化性が良好であり、２パス以下でタックフリーになるものを○（合格）とし、それ以上の照射を必要とするものを×（不合格）とした。
【０１７２】
（１１）版離れ性
紫外線硬化後、ＰＥＴフィルムを電離放射線硬化樹脂層と共に、ロール凹版から剥離し、欲するロール凹版の形状を転写したレンズ配列連続シートを製造する際、剥離時に大きな負荷がなく、製造できるときを○（合格）、剥離時に大きな剥離音や負荷がかかって、シートに折れ目等できてしまうものを×（不合格）とした。
【０１７３】
（１２）初期外観
光学シート製造後の外観を目視にて判定した。判定基準は、均一なレンズ表面形状が得られたものを○（合格）、一部に割れや、形状の抜け落ちが見られたものを△（やや不合格）、全面に割れや、形状の抜け落ちがみられたものを×（不合格）とした。
【０１７４】
（１３）沸水密着性
作成された光学レンズシートを、９５℃以上の沸水に４時間浸漬させ、室温に取り出し、２時間後の密着性をＪＩＳ Ｋ−５４００に準拠して測定した。数字は密着小片の残存数を示し、１００は全ての升目小片（１００個）が残存していたことを、０は全ての小片が剥離したことを示す。
【０１７５】
（１４）沸水後外観
作成された光学レンズシートを、９５℃以上の沸水に４時間浸漬させ、室温に取り出し、外観塗膜状態を目視にて評価した。
【０１７６】
（１５）促進耐候密着性
作成された光学レンズシートを、フェードメーター（スガ試験機：ブラックパネル温度：６３±３℃）で４００時間促進耐候試験をおこなって、密着性をＪＩＳ Ｋ−５４００に準拠して測定した。数字は（１３）沸水密着性と同様に、密着小片の残存数を表わす。
【０１７７】
実施例及び比較例中に使用した樹脂の略語を下記に示す。
ＢＢＡ：テトラブロムビスフェノールＡ型エポキシアクリレート
ＢＢＦ：テトラブロムビスフェノールＦ型エポキシアクリレート
ＢＡ ：ビスフェノールＡ型エポキシアクリレート
【０１７８】
ＰＩＰＡ：２−フェニル−２−（４−アクリロイルオキシエトキシフェニル）プロパン
ＢＰＯＥＡ：２，４，６−トリブロモフェニルエトキシアクリレート
【０１７９】
ＴＨＦＡ：テトラヒドロフルフリルアクリレート
ＰＧＡ：２−ヒドロキシ−３−フェノキシ−プロピルアクリレート
（フェニルグリシジルエーテルアクリレート）
＃１８４：１−ヒドロキシシクロヘキシルフェニルケトン
ｄ１１７３：２−ヒドロキシ−２−メチル−１−フェニルプロパン−１−オン
【０１８０】
また、表中の（ａ）は、環状構造を有し、二つ以上のアクリレート基を有するエポキシ（メタ）アクリレートを、（ｂ）は、環状構造を有する単官能（メタ）アクリレートを、（ｃ）は光重合開始剤を表わす。更に、表中のＲＳＨ１及びＲＳＨ２は、比較合成例１、２で合成されたウレタンアクリレートである。
【０１８１】
表中の評価結果の単位を下記に示す。
粘度：１０００ｃｐｓ／２５℃
ＤＢ濃度：樹脂組成物中の（メタ）アクリレート官能基の濃度（ｍｍｏｌ／ｇ）
破断強度：Ｋｇ／ｃｍ^２
破断伸度：％
【０１８２】
弾性率（引張弾性率）：１００Ｋｇ／ｃｍ^２
σ２／σ１：弾性評価
ＳＳ：Ｓ−Ｓカーブのパターン評価
置き痕：（４）置き痕での評価
光線透過：（５）光線透過率による評価
【０１８３】
硬度：（６）鉛筆硬度での評価
収縮率：（７）硬化収縮率での評価
カール：（８）カール性での評価
付着：（９）初期密着性での評価
硬化性：（１０）硬化性での評価
屈折率：（２）屈折率による、２５℃での液状屈折率及び硬化物屈折率。
【０１８４】
図１３及び図１４は、各々実施例１及び実施例３で得られた樹脂組成物硬化物の引張応力（ｋｇ／ｃｍ^２）と歪（％）との関係を示す図である。これらは実施例のＳ−Ｓ曲線の一例として示した。全ての実施例のＳ−Ｓ曲線に降伏点は見られなかった。
【０１８５】
また図１５は比較例１で得られた樹脂組成物硬化物の引張応力（ｋｇ／ｃｍ^２）と歪（％）との関係を示す図である。明らかな降伏点が認められる。またσ２とσ１は特に図示しなかったが、測定した（σ２／σ１）は表中に記載した。
【０１８６】
（実施例７〜１０）面光源の作成
実施例１〜４で作成したレンズ配列シートを用いて、図１１に示すようなエッジライト型面光源を各々作成し、面光源としての性能を評価した。
（導光板）
厚さ４ｍｍ、面積が対角線長９．４インチ、材質は透明アクリル樹脂。
【０１８７】
（板光拡散反射層）
導光板裏面に白色インキ（酸化チタン顔料使用）を用いて、散点パターン状の印刷を施し、更にその裏面に、アルミニウム蒸着ＰＥＴフィルムを積層し、鏡面反射層とした。散点パターンの面積率は、光源から遠ざかるに従って、増大するようにした。尚、２燈型であるため、中央で散点パターンの面積率が最大となるようにした。
【０１８８】
（光源）
導光板の両側端に各１本、合計２本の直径３ｍｍの冷陰極管型の蛍光灯（消費電力４Ｗ）を設置し、導光板に面した側以外を反射鏡で被覆した。
（光拡散透明性シート）
厚さ３８ｍｍのサンドブラストＰＥＴシートを２枚重ねたものを用いた。
【０１８９】
作成した面光源は、出光面（レンズ配列シートの表面）から３０ｃｍの位置に輝度計（トプコンＢＭ−８）にて輝度を測定した。測定は出光面の法線方向（０゜方向）を中心として、−９０゜〜＋９０゜の範囲で測定し、角度依存性（配光特性、半値角）も併せて測定した。更に、目視により、置き痕が輝度の分布、変化として認識できるか否かを確認した。
【０１９０】
測定の結果、作成した面光源は、いずれも法線輝度が１２００ｃｄ／ｃｍ^２以上（１２００〜１２５０ｃｄ／ｃｍ^２）であり、また、半値角もいずれも６５゜以上（６５゜〜７５゜）で、且つ、置き痕に由来する輝度変化も全く観察されず、良好な面光源が作成できた。
【０１９１】
【表１】

【０１９２】
【表２】

【０１９３】
【表３】

【０１９４】
【表４】

【０１９５】
【表５】

【０１９６】
【発明の効果】
本発明は、表面硬度、及び屈折率が高く、硬化時の収縮変形や、硬化後の変形や置き痕、耐候性低下の問題がない、優れた光学物品用電離放射線硬化型樹脂組成物、その硬化物を用いた優れた光学物品及び面光源を提供できる。
【図面の簡単な説明】
【図１】引張応力（ｋｇ／ｃｍ^２）と歪（％）との関係（Ｓ−Ｓ曲線）を示す模式図である。縦軸は引張応力（ｋｇ／ｃｍ^２）、横軸が歪（％）を表わす。（降伏点が見られないパターンである。パターンＡ）
【図２】引張応力（ｋｇ／ｃｍ^２）と歪（％）との関係（Ｓ−Ｓ曲線）を示す模式図である。縦軸は引張応力（ｋｇ／ｃｍ^２）、横軸が歪（％）を表わす。（降伏点が見られるパターンである。パターンＢ）
【図３】引張応力（ｋｇ／ｃｍ^２）と歪（％）との関係（Ｓ−Ｓ曲線）を示す模式図である。縦軸は引張応力（ｋｇ／ｃｍ^２）、横軸が歪（％）を表わす。（降伏点が見られないパターンである。パターンＡ）
【図４】本発明によるレンズ配列シートの連続製造方法の一例を示す図である。
【図５】本発明によるレンズ配列シートの例を模式的に示した図である。
【図６】本発明によるレンズ配列シートの例を模式的に示した図である。
【図７】本発明によるレンズ配列シートの例を模式的に示した図である。
【図８】本発明によるレンズ配列シートの例を模式的に示した図である。
【図９】本発明によるレンズ配列シートの例を模式的に示した図である。
【図１０】本発明によるレンズ配列シートの例を模式的に示した図である。
【図１１】本発明による面光源の一例を示す図である。
【図１２】本発明による面光源の一例を示す図である。
【図１３】実施例１で得られた樹脂組成物硬化物の引張応力（ｋｇ／ｃｍ^２）と歪（％）との関係図である。
【図１４】実施例３で得られた樹脂組成物硬化物の引張応力（ｋｇ／ｃｍ^２）と歪（％）との関係図である。
【図１５】比較例１で得られた樹脂組成物硬化物の引張応力（ｋｇ／ｃｍ^２）と歪（％）との関係図である。
【符号の説明】
１ ロール凹版
２ 凹部
３ 未硬化の電離放射線硬化型樹脂組成物（Ａ）
３ａ 硬化した電離放射線硬化型樹脂組成物（Ａ）
４ 基材シート（Ｃ）
５ 押圧ロール
６ 送りロール
７ 硬化装置
８ 送りロール
９ レンズ配列シート
１０ Ｔダイ型ノズル
１１ 乾燥装置
１２ 液溜
Ｐ 繰り返し周期
β 頂角
４１ 単位レンズ
５１ 導光体
５２ 光源
５３ 光反射層
５４ ランプハウス
６０ 透過型液晶表示板
１００ 面光源
２００ 液晶表示装置（ＬＣＤ）[0001]
BACKGROUND OF THE INVENTION
The present invention is a illuminating means for a backlight (back light source) of a translucent display such as a transmissive liquid crystal display element, a video projector, an advertising board, a light diffusing plate, and a rear reflecting lens, or a hologram, a projection screen, etc. Ionizing radiation curable resin composition for optical articles, which is useful as an optical article, has a high surface hardness, and does not suffer from shrinkage deformation upon curing, deformation and marking after curing, or deterioration in weather resistance, and the optical article The present invention relates to an optical article having excellent performance using an ionizing radiation curable resin composition, and a surface light source.
[0002]
[Prior art]
In recent years, in transmissive liquid crystal display elements, the demand for light weight and low power consumption has further increased, and the light energy of the back light source has been effectively used to achieve uniform and effective in the necessary and sufficient direction and diffusion angle. Various proposals have been made for the purpose of collecting light source light. In these methods, a light source is usually arranged on the side surface of a light guide made of a plate material such as transparent acrylic resin, and the light source light incident on the light guide from the side surface is reflected by a reflection layer on the back surface of the light guide to guide the light. Light source light is emitted from the light emitting surface on the upper surface of the light body.
[0003]
At that time, an optical article having a prism action or a lens action, that is, a lens arrangement sheet, is arranged on the upper surface of the light guide to obtain a desired output light diffusion angle, emission direction, and peak direction luminance. Surface light sources are used. A surface light source in which a light source is disposed on the side surface of such a light guide is called an edge light type (or side light type) surface light source because of its configuration. In addition, there is a direct type surface light source in which a light source is disposed directly below a diffusion sheet or a lens array sheet. However, the use of a surface light source for a liquid crystal display element is limited because it is thick.
[0004]
Conventionally, a lens array sheet has been generally manufactured by injection molding or hot press molding of a thermoplastic resin disclosed in US Pat. No. 2,482,598 and US Pat. No. 3,565,978. However, these manufacturing methods have a problem that a long time is required for heating and cooling at the time of manufacturing, and the productivity is low, and further, the durability of the manufactured lens array sheet is not sufficient. It was.
[0005]
In recent years, a method of manufacturing a replica of a lens matrix by interposing a reactive resin between the lens matrix and a transparent film and curing the reactive resin with heat or ultraviolet rays has been proposed. US Pat. No. 2,524,862 describes a method for producing an optical component by photopolymerization of a monomer such as (meth) acrylic acid or methyl methacrylate or a partially polymerized composition.
[0006]
In US Pat. No. 3,689,346 and US Pat. No. 3,935,359, a crosslinkable, partially polymerized resin composition such as an acrylic ester is injected into a lens matrix and solidified by active energy rays or heat. According to the method, a method for continuously producing a lens array sheet is described.
[0007]
In Japanese Patent Laid-Open No. 48-21546, a solvent-free photocurable resin is sandwiched between transparent sandwiched bodies, exposed from the transparent portion, and the exposed portion is cured, depending on the contact surface of the sandwiched body. A method of manufacturing an optical element for obtaining a photo-curing resin molded body having a different shape is disclosed.
[0008]
U.S. Pat. No. 4,376,800 describes a method for producing an optical article by ultraviolet curing of a composition comprising an acrylic monomer and urethane acrylate. However, these methods have the disadvantages that the use of monomers having strong skin irritation and toxicity causes deterioration of the working environment and time until the reaction is completed, resulting in poor productivity. In addition, there are problems that the mechanical properties are poor and the film curls and the like is deformed by shrinkage during curing.
[0009]
Japanese Examined Patent Publication No. 62-51725 discloses that a radiation-polymerizable resin containing a saturated hydrocarbon or a phenyl group is deposited on a metal die (matrix) having an information track, and then the above-mentioned die of the polymerizable resin is used. A substrate is provided on the surface opposite to the substrate, or the polymerizable resin layer is previously deposited on the substrate, and then the polymerizable molding resin layer having the substrate is deposited on the die, and the polymerizable molding resin Discloses a method for duplicating a plastic information carrier such as a CD or LD by removing the polymerizable molding resin layer and the substrate bonded thereto from the die after photocuring.
[0010]
U.S. Pat. No. 3,689,346 and JP-A-5-169015 disclose that an ionizing radiation curable resin composition is filled in a mold formed by engraving a shape of a desired lens arrangement, and ultraviolet rays, electron beams A method for producing a microlens array sheet is disclosed in which the oligomer composition is crosslinked and cured by irradiation with ionizing radiation such as, and then the cured product is released from a mold.
[0011]
Further, in US Pat. No. 4,576,850 and JP-B-4-5681, a mixture of compounds called so-called soft segments and hard segments is crosslinked and cured by ultraviolet irradiation, thereby improving thermal dimensional stability and mechanical properties. A method for improving physical properties is disclosed. However, these methods require a relatively long curing time, and the problems of a decrease in the surface hardness of the resulting cured product due to the introduction of the soft segment, deformation during the curing of the lens array sheet, and a decrease in weather resistance remain.
[0012]
Japanese Laid-Open Patent Publication No. 4-329501 discloses a microlens array produced by the same casting method of ionizing radiation curable resin, composed of a polyvalent (meth) acrylate ionizing radiation curable material, and the cured product. Young's modulus of 1000kg / cm²~ 5000kg / cm²It is disclosed to select (25 ° C.).
[0013]
That is, Young's modulus is 1000 kg / cm²If it is less than the range, deformation is likely to occur when the sheet-like cured product is laminated, and the shape of the formed optical article, particularly the shape of the pressurized tip, may be distorted, and the optical characteristics may change. / Cm²It is disclosed that warpage is liable to occur due to polymerization shrinkage and is not preferable.
[0014]
In JP-A-6-67004, for the same reason, the elastic modulus at 25 ° C. after curing of the active energy ray-curable resin is 10,000 to 50,000 kg / cm.²It is disclosed that it is preferable to be in the range.
[0015]
However, when an optical article is actually manufactured, it has been found that it is difficult to completely solve the following drawbacks even with the optical article manufacturing methods according to these conventional techniques. That is,
[0016]
(I) When an optical article is made using a hard resin (a resin having a high Young's modulus), the shape reproducibility and surface hardness of the molded product are good, but particularly when the molded product is a sheet. It often causes warping and optical distortion. In addition, when deformation such as dents due to bending or pressing is applied, the deformation remains permanently and does not return (placement mark). Further, when an external force is applied, cracks and breaks are likely to occur.
[0017]
(II) On the other hand, when an optical article is made using a flexible resin (a resin having a low Young's modulus), the above-mentioned drawbacks are improved, but the optical article is easily deformed, and the molded product is particularly sheet-like. In such a case, when these are laminated or laminated with another plate-like body such as a liquid crystal display (LCD) or a light guide plate of an edge light surface light source, deformation is likely to occur, and the shape of the formed lens, particularly pressure is applied. The shape of the tip portion is distorted, the optical characteristics are changed, and the surface hardness is insufficient, so that wear and scratches are likely to occur.
[0018]
In particular, it is extremely difficult to completely control the placement marks in (I). Even if all the other problems are solved, the placement marks are often generated. Had the problem that the above-mentioned other drawbacks occurred.
[0019]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to solve the above-mentioned drawbacks (I) and (II), in particular, placement marks, excellent in transparency, refractive index, surface hardness, etc., with a short curing time, and in productivity. An object of the present invention is to provide an excellent ionizing radiation curable resin composition for optical articles, an optical article using the resin composition, and a surface light source composed of the optical article.
[0020]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventors have intensively studied and as a result, it is not sufficient to simply examine only the elastic modulus, which has a cyclic structure and has two or more (meth) acrylate groups. An epoxy (meth) acrylate (a) having a specific monofunctional (meth) acrylate (b) having a cyclic structure, and a (meth) acrylate functional group concentration of 0.2 to 5.0 mmol / g, And in the relationship diagram between tensile stress and strain, the ionizing radiation curable resin composition in which the cured product does not have a yield point has no particular imprint, and the cured product has a high hardness and refractive index and is durable. It is found that the composition is an ionizing radiation curable resin composition that is suitable for optical articles, has excellent properties, has little deformation such as curling at the time of curing, can be designed in a fine shape, has a high curing speed, and completes the present invention. It came to.
[0021]
That is, the present invention includes an epoxy (meth) acrylate (a) having a cyclic structure and having two or more (meth) acrylate groups, 2-hydroxy-3-phenoxy-propyl (meth) acrylate, 2-phenyl 2- [4- (meth) acryloyloxyphenyl] propane, 2-phenyl-2- [4- (meth) acryloyloxyalkoxyphenyl] propane, benzyl (meth) acrylate and (meth) acryloyloxyphthalic acid A monofunctional (meth) acrylate (b) having at least one cyclic structure selected from the group, the (meth) acrylate functional group concentration is 0.2 to 5.0 mmol / g, and tensile stress and strain In the relationship diagram, the cured product does not have a yield point, and the ionizing radiation curable resin group for optical articles It is intended to provide a thing.
[0022]
In the present invention, it is preferable that the monofunctional (meth) acrylate (b) is 2-phenyl-2- [4- (meth) acryloyloxyphenyl] propane and / or 2-phenyl-2- [4- The present invention provides an ionizing radiation curable resin composition for optical articles, which is (meth) acryloyloxyalkoxyphenyl] propane.
[0023]
Further, according to the present invention, the epoxy (meth) acrylate (a) is a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a partially halogen substituted bisphenol A type epoxy resin, or a partially halogen substituted bisphenol F type. An ionizing radiation curable resin for optical articles, which is an epoxy (meth) acrylate obtained by reacting one or more epoxy resins selected from the group consisting of epoxy resins and hydrogenated bisphenol A type epoxy resins with (meth) acrylic acid A composition is provided.
[0024]
In addition, the present invention provides the ratio (σ2 / σ1) of the stress (σ2) at the time of fracture of the cured product and the intersection (σ1) of the tangent at the tensile deformation start point on the tensile stress-strain curve and the stress at the strain at fracture. ) Is 0.5 or more, and the tensile modulus of the cured product is 2000 to 40000 kg / cm²An ionizing radiation curable resin composition for optical articles is provided.
[0025]
The present invention also relates to an optical article comprising a cured product of the ionizing radiation curable resin composition for optical articles of the present invention and an ionizing radiation curable resin composition comprising the ionizing radiation curable resin composition for optical articles of the present invention. Optical article comprising cured product layer (A) and sheet-like transparent resin layer (C), cured product layer (A) of ionizing radiation curable resin composition, adhesive layer (B), and sheet-like transparent resin And an optical article comprising the layer (C).
[0026]
Furthermore, the present invention is provided on the rear surface of the light guide body, a light guide body made of a translucent flat plate, a light source unit provided adjacent to one or more of the side end faces of the light guide body, and It is a surface light source composed of a light reflecting layer and the optical article of the present invention laminated on the light emitting surface of the light guide surface.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
The optical article referred to in the present invention is one in which a large number of minute unit lenses or minute unit prisms are arranged in a one-dimensional or two-dimensional direction. Specifically, it is a lenticular lens, which will be described later, and its uses include a light diffusing plate, a light condensing plate, and a projection television screen for a backlight (back light source) such as a transmissive liquid crystal display device, an electric signboard, and an advertising lamp. And lenticular lenses, frennel lenses, retroreflective sheets, etc. for condensing lenses, diffraction gratings, holograms, grooves and holes modulated to record / reproduce information due to changes in light reflectance or transmittance, etc. An optical article such as a recording medium such as a compact desk or a video desk is formed, and many of them have a fine structure for the purpose of efficiently reflecting, refracting, and condensing light on the surface.
[0028]
These optical articles such as a lens array sheet may be locally deformed by an external force during the manufacturing process or when the optical article is incorporated into an apparatus. For example, when a sheet-like optical article is wound up with a foreign object or air bubble in between, a large stress is locally applied to the location where the foreign object exists. In some cases, a sheet take-up roll or a plurality of sheet-like optical articles are stored while being stacked.
[0029]
In these cases, stress is concentrated locally by its own weight. In this case, the local deformation remains as distortion, and even after the stress is released, permanent distortion (deformation) still remains, which may become a so-called mark. This is considered to be because plastic deformation occurs in the optical article due to excessive stress.
[0030]
In order to solve this problem, the ionizing radiation curable resin composition for optical articles of the present invention is characterized in that the cured product does not have a yield point in the relationship diagram between tensile stress and strain. is there. In the present invention, the cured product does not have a yield point, which means that tensile stress (kg / cm²) And strain (%), that is, a tensile stress-strain curve of a cured product, or a relationship diagram generally referred to as an SS (stress-strain) curve or an SS characteristic, for example, as shown in FIG. The one having no yield point is not preferable, and the one having the yield point as shown in FIG. 2 is not preferable.
[0031]
Further, even when the yield point does not appear as shown in FIG. 3, the stress (σ2) at the time of fracture and the intersection (σ1) between the tangent at the starting point of tensile deformation on the tensile stress-strain curve and the stress at the strain at break Ratio, that is, (σ2 / σ1) showing a value of 0.5 or more is particularly preferable, and when (σ2 / σ1) is less than 0.5, the deformation of the cured product can be restored after the external force is removed. It takes a long time, which is not preferable.
[0032]
1 to 3 show tensile stress (kg / cm) measured at a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 2% according to the measurement method of JIS K-7113.²) And strain (%). The strain (%) is the length of the sample after tension (l) and the length of the initial sample (l₀) With the initial sample length (l₀), And the percentage is shown as a percentage. Strain (%) = [(l−l₀) / L₀] × 100.
[0033]
In particular, the placement mark cannot be completely eliminated simply by controlling the elastic modulus. The occurrence of the placement mark is related to the presence or absence of the yield point of the tensile stress-strain curve, and according to the present invention having no yield point. A cured product using the ionizing radiation curable resin composition for optical articles can be obtained with no traces. That is, the optical article comprising the specific ionizing radiation curable resin composition of the present invention is a cured product that does not have a yield point in the stress-strain curve, and when the applied stress is within the elastic limit, When it is released, it is restored to its original shape by the elastic restoring force, and there is no placement mark.
[0034]
The ionizing radiation curable resin composition for optical articles of the present invention may be any one as long as the cured product satisfies the behavior of the tensile stress-strain curve as described above, or further the range of elastic modulus, and is particularly limited. Not.
[0035]
In addition, as a particularly preferred embodiment of the present invention, the soft segment component is not included in the resin composition, and the component is constituted by a resin component called a hard segment, the structural component is structurally hard, the hardness of the cured product, and The refractive index is high. Such a hard segment has a cyclic structure, more preferably a benzene ring or a substituted benzene ring, and more preferably 30% by weight or more of the benzene ring or substituted benzene ring in the system. It preferably has a structure.
[0036]
Regarding the elastic modulus of the cured product, if the elastic modulus is too large, optical distortion, cracks and the like tend to occur. If the elastic modulus is too small, lens deformation and the like during lamination tend to occur. These can be evaluated using compression modulus or flexural modulus, but tensile modulus (also referred to as Young's modulus or longitudinal modulus) as the modulus of elasticity due to good correlation and ease of measurement. It is preferable to evaluate by.
[0037]
The tensile modulus of the cured product of the ionizing radiation curable resin composition of the present invention is 2500 to 50000 kg / cm.²Preferably in the range of 2500 to 40000 kg / cm.²Particularly preferably, 2500 to 35000 kg / cm²It is. Tensile modulus is 2500 kg / cm²If it is less than the range, the optical article is easily deformed, and when it is laminated and used, the optical article is deformed, and the shape and optical characteristics are distorted.
[0038]
On the other hand, the tensile modulus is 50000 kg / cm²In the case of exceeding, shrinkage at the time of curing, warpage and optical distortion are often generated, and cracks and breaks are likely to occur. In this case, there is a tendency that when a deformation such as a bending mark or a dent caused by pressing is applied during manufacturing, a deformation remains permanently and does not return to the original state during manufacturing.
[0039]
The hardness of the ionizing radiation curable resin is affected by the rigidity of the resin skeleton, the crosslinking density, the reaction rate, and the like. When a soft component is introduced as the resin skeleton, the hardness becomes low at the same crosslink density. In order to avoid this, if a method of increasing the crosslink density to compensate for the hardness is taken, the shrinkage of curing increases when the ionizing radiation curable resin is cured, and the optical article is likely to be deformed.
[0040]
In order to reduce the deformation of the optical article, that is, the curling of the lens arrangement sheet, etc., as one method of keeping the crosslinking density of the ionizing radiation curable resin composition small, to an ionizing radiation curable oligomer resin composition having a large molecular weight And addition of thermoplastic polymers have been studied. However, if a reactive oligomer having a large molecular weight, a thermoplastic polymer, or the like is used in order to reduce the crosslinking density of the ionizing radiation curable resin composition, the viscosity of the resin composition before curing is significantly increased.
[0041]
For the uniform application of the ionizing radiation curable resin composition to the mother die and the reproduction of the mother die having a fine structure, the viscosity of the resin composition used is generally in the range of 1000 to 12000 cps at 25 ° C. It is desirable that it is preferably 1000 to 8000 cps. If it exceeds 12000 cps, or conversely, 1000 cps or less, it is difficult to sufficiently mold the resin composition up to the fine part of the matrix and continuous application becomes difficult.
[0042]
However, if a special coating method is used, it is not particularly problematic to apply a resin composition of 1000 cps or less, and use of such a low-viscosity resin composition may be preferable. Solvents and reactive diluents are added.
[0043]
In order to adjust the viscosity of the resin composition, if a solvent or the like is added to lower the viscosity of the composition, a solvent volatilization step is required. In patterning after volatilization of the solvent, a fine matrix is generally used. Although it is difficult to transfer the mold pattern, it is possible to adjust the viscosity by adding a solvent by applying a means such as removing the solvent stepwise after coating the matrix and filling the uneven pattern. In addition, it is possible to add a reactive diluent in order to reduce the viscosity of the resin composition. However, if it is added in a large amount, the cure shrinkage rate of the composition increases, and at the time of manufacture or over time. Deformation of the lens array sheet is not preferable.
[0044]
In addition, as a method of reducing the elastic modulus of a cured coating film, a polyacrylic resin mainly composed of polyether, aliphatic polyester, polysiloxane, polyolefin, and acrylate ester as a soft segment component having a low glass transition point in the molecular structure. A method of introducing the above can be considered. However, the introduction of such a soft segment component lowers the hardness of the cured product, resulting in problems such as surface scratches and reduced durability.
[0045]
Since the specific resin composition of the present invention does not have a high crosslinking density, deformation of the cured product can be suppressed. That is, the ionizing radiation curable resin composition for a specific optical article according to the present invention has a functional group having polarity in the molecule, and has a structure in which hydrogen bonds are formed between the molecules by the polar functional group. Yes.
[0046]
In general, a hydrogen bond is formed between the XH group of the atoms X and Y having a high electronegativity and a Y atom, and examples of the atom having a high electronegativity include oxygen and nitrogen atoms. More specifically, a hydroxyl group of X═O and an oxygen atom of Y═O contained in the epoxy (meth) acrylate or monofunctional (meth) acrylate in the ionizing radiation curable resin composition for optical articles of the present invention. Hydrogen bonds are formed between the two.
[0047]
The bond energy of the hydrogen bond is 1 to 8 Kcal / mol, which is weaker than that of a normal chemical bond, but a pseudo-crosslinked structure is formed between the molecules due to the hydrogen bond formed between the molecules. The That is, the hydrogen bond formed between the molecules increases the cohesive force between the molecules, thereby increasing the curing rate and further increasing the physical property strength.
[0048]
As described above, the ionizing radiation curable resin composition for optical articles having the specific composition of the present invention has the ability to form intermolecular hydrogen bonds, so that it is compared with a resin composition composed only of other hard segments. Thus, the curing speed is fast and the cured product has toughness, so that deformation and cracking of the lens array sheet at the time of manufacture can be prevented, and the impact resistance of the lens array sheet can be improved.
[0049]
That is, as the epoxy (meth) acrylate (a) having a cyclic structure used in the present invention, bisphenol A type epoxy resin, bisphenol F type epoxy resin, partially halogen-substituted bisphenol A type epoxy resin, and partially halogen-substituted And an epoxy (meth) acrylate obtained by reaction of one or more epoxy resins selected from the group consisting of bisphenol F type epoxy resins, hydrogenated bisphenol A type epoxy resins, and mixtures thereof with (meth) acrylic acid. .
[0050]
That is, bisphenol A type epoxy (meth) acrylate, phenol novolak, cresol novolak type epoxy (meth) acrylate, naphthalene skeleton epoxy (meth) acrylate, bisphenol F type epoxy (meth) acrylate and their halides, water Additives epoxy (meth) acrylate, or a mixture thereof.
[0051]
In addition, epoxy (meth) acrylate (a) having such a cyclic structure generally has a higher refractive index and a thinner optical article than a cured resin using only a soft segment or a combination of a soft segment and a hard segment. And has the advantage of improving optical characteristics such as luminance as a surface light source. In particular, a brominated epoxy (meth) acrylate that is a partially bromo-substituted product is preferable because the cured product has a high refractive index and flame-retardant properties. A hydrogenated product is preferable because weather resistance and discoloration resistance are improved.
[0052]
These epoxy (meth) acrylates are obtained by reacting a compound having an ethylenically unsaturated double bond and a carboxylic acid with a glycidyl ether compound having a cyclic structure in the molecule. It is produced by an addition reaction. At this time, the ring opening of glycidyl ether generates a secondary hydroxyl group as a residue, and this hydroxyl group becomes a proton donor that forms a hydrogen bond.
[0053]
The monofunctional acrylate (b) having a cyclic structure used in the present invention includes 2-hydroxy-3-phenoxy-propyl (meth) acrylate, 2-phenyl-2- [4- (meth) acryloyloxyphenyl] propane, 2- One or more monofunctional (meth) acrylates selected from the group consisting of phenyl-2- [4- (meth) acryloyloxyalkoxyphenyl] propane, benzyl (meth) acrylate and (meth) acryloyloxyphthalic acid; Of these, 2-phenyl-2- [4- (meth) acryloyloxyphenyl] propane and / or 2-phenyl-2- [4- (meth) acryloyloxyalkoxyphenyl] propane is preferably used.
[0054]
The structural formula of 2-phenyl-2- [4- (meth) acryloyloxyalkoxyphenyl] propane is shown in general formula 1.
(General formula 1)
[0055]
[Chemical 1]

[0056]
Wherein R is hydrogen or a methyl group, R₁Represents a hydrocarbon group having 1 to 5 carbon atoms, and n represents an integer of 0 to 3. )
[0057]
The monofunctional (meth) acrylate (b) can be used in combination with a monofunctional (meth) acrylate having a cyclic structure other than this. Illustrative examples are isobornyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, glycidyl cyclocarbonate (meth) acrylate, phenoxyethyl acrylate, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, di Cyclopentenyl (meth) acrylate, glycidyl (meth) acrylate,
[0058]
Selected from the group consisting of phenoxyethylene glycol (meth) acrylate, adamantyl (meth) acrylate, monophorin (meth) acrylate, 2,4,6-tribromophenyl acrylate, and 2,4,6-tribromophenylalkoxy acrylate One or more types of monofunctional (meth) acrylates may be mentioned.
[0059]
Moreover, the monofunctional reactive diluent which has cyclic structures other than these can also be used for this invention. Typical examples of these include styrene and vinyl pyrrolidone.
[0060]
Furthermore, monofunctional reactive dilutions having polar functional groups such as hydroxyl groups, cyclic ether groups, cyclocarbonate groups, amino groups, carboxyl groups, phosphoric acid groups, sulfonic acid groups and the like, and alkali metal salts thereof and cyclic structures Agents are also preferably used. These include tetrahydrofurfuryl (meth) acrylate, glycidyl cyclocarbonate (meth) acrylate, phenoxyethyl acrylate, 2-hydroxy-3-phenoxy-propyl (meth) acrylate, and the like.
[0061]
The resin composition of the present invention by blending an epoxy (meth) acrylate (a) having a cyclic structure, a monofunctional (meth) acrylate (b) having a cyclic structure, and a photoinitiator (c) to be added as necessary. The (meth) acrylate functional group concentration of the system is required to be 0.2 to 5.0 mmol / g, but the epoxy (meth) acrylate (a) having the above cyclic structure and the cyclic structure are included. The monofunctional (meth) acrylate (b) can be used alone or in combination of two or more as required. When the (meth) acrylate functional group concentration is lower than 0.2 mmol / g, the curability is lowered, the viscosity is increased, and the workability is deteriorated.
[0062]
Moreover, when the (meth) acrylate functional group concentration is higher than 5.0 mmol / g, the cured sheet curls due to curing shrinkage. With a (meth) acrylate functional group concentration of 0.2 to 5.0 mmol / g, curability is good, deformation of the film such as curl during curing can be prevented, and good surface hardness can be obtained. I can do it.
[0063]
Among the optical articles of the present invention, in particular, the lens arrangement sheet has a problem of curling caused by its deformation. Curling can be evaluated by cutting out the produced optical lens sheet to A4 size, leaving the lens forming surface on a horizontal plane, and measuring the height at which the end of the lens sheet is curled from the horizontal plane. . The curl of the cured product using the ionizing radiation curable resin composition for optical articles of the present invention is preferably 1 mm or less by the evaluation method.
[0064]
Furthermore, since the deformation of the lens array sheet, that is, the curling property, has a strong correlation with the curing shrinkage rate of the resin, by determining the curing shrinkage rate of the ionizing radiation curable resin composition for optical articles used in the present invention. The resin composition that does not cause curling can be determined. That is, the curing shrinkage rate can be calculated from the resin specific gravity (DL) before curing and the resin specific gravity (DS) after curing by the following formula 1, and the ionizing radiation curable resin composition for optical articles used in the present invention can be calculated. The cure shrinkage is preferably 5.5% or less.
Curing shrinkage (%) = [(DS−DL) / DS] × 100 (Formula 1)
[0065]
Moreover, the preferable mixture ratio of this invention is 10-90 weight% of epoxy (meth) acrylate (a) which has a cyclic structure, More preferably, it is 30-85 weight%. Furthermore, the monofunctional (meth) acrylate (b) having a cyclic structure is 20 to 70% by weight. When the monofunctional (meth) acrylate (b) is present in an amount of more than 70% by weight, the yield point is likely to appear in the tensile test, and the cured product easily undergoes plastic deformation.
[0066]
The ionizing radiation curable resin composition for optical articles of the present invention is naturally excellent in transparency, and has a light transmittance of at least 80% in a wavelength region of 400 to 900 nm of a 0.4 mm thick sheet, It is 85% or more, and preferably the transmittance is 90% or more.
[0067]
Among the optical articles of the present invention, in particular, a lens arrangement sheet has a problem of a mark that is caused by a deformation caused by an external force not being restored. The lens array sheet is manufactured as a long belt-like sheet and is manufactured and stored by being wound on a cigarette. At this time, the end of the sheet is fixed to the cigarette with an adhesive tape, and the lens array sheet is wound on the cigarette. In this case, the swell of the adhesive tape portion protrudes as a step, and the lens arrangement sheet is deformed. When this deformed portion is permanently deformed, it becomes a so-called mark.
[0068]
Placement marks can be evaluated by whether or not the marks can be confirmed when an arbitrary pressure is applied only to the unit area that is a part of the created optical lens sheet, and the pressure is removed by leaving for an arbitrary time. Is possible. Specifically, an adhesive tape having a thickness of 75 μm and 1 inch square is placed on an iron flat plate, and 60 lens array sheets of 10 cm × 10 cm are laminated thereon, and the temperature is set to 500 g / cm at 40 ° C.²After the load is removed for 3 days and the load is removed, it is judged visually by transmitted light and reflected light.
[0069]
It is most preferable that there is no placement mark on the prepared sheet. However, when an optical lens sheet is wound around a long roll or the like, the placement mark is usually not confirmed on the 21st and subsequent sheets from the adhesive tape. If so, a lens array sheet having no practical problem can be created.
[0070]
The optical article of the present invention may cause a coating film defect such as a scratch on the surface of the cured product at the time of production or display mounting. However, since these are used as an optical article, these minute scratches are fatal defects. It becomes. Therefore, the resin composition of the present invention is required to have a high surface hardness. Specifically, the pencil hardness is preferably H or more according to JIS K-5400.
[0071]
In addition, if necessary, in the resin composition, various additives such as ultraviolet absorbers, light stabilizers, and antioxidants can be used to improve coating properties, improve paintability, and release properties from the matrix. It is also possible to add agents, rheology control agents, silicon additives, defoamers and the like.
[0072]
In the present invention, ionizing radiation is used as the curing energy ray. As the ionizing radiation, visible light, ultraviolet rays, electromagnetic waves such as X-rays, or charged particle beams such as electron beams are used. Of these, visible light, ultraviolet rays, or electron beams are often used practically. is there. In particular, when the resin preparation and the resin composition of the present invention are cured using visible light or ultraviolet light, they are dissociated by ultraviolet light or visible light having a wavelength of 1,000 to 8,000 angstroms to generate radicals. Such a photo (polymerization) initiator (c) should be used.
[0073]
As such a photo (polymerization) initiator, known and usual ones can be used in combination, but among them, representative examples include 4-dimethylaminobenzoic acid, 4-dimethylaminobenzoic acid ester, alkoxyacetophenone. , Benzyldimethyl ketal, benzophenone and benzophenone derivatives, alkyl benzoylbenzoates, bis (4-dialkylaminophenyl) ketones,
[0074]
Benzyl and benzyl derivatives, benzoin and benzoin derivatives, benzoin alkyl ethers, 2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, thioxanthone and thioxanthone derivatives, 2,4,6-trimethylbenzoyldiphenoylphosphine Oxide,
[0075]
Examples include 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1.
[0076]
Among these, 1-hydroxycyclohexyl phenyl ketone, thioxanthone and thioxanthone derivatives, 2,4,6-trimethylbenzoyldiphenoylphosphine oxide, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino Since one or more mixed systems selected from the group of -1-propanone and 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one have high curability, preferable.
[0077]
The photoinitiator is preferably added in the range of 0.5 to 10% by weight. Moreover, a well-known and usual photosensitizer can also be used together with a photo (polymerization) initiator. Examples of such photosensitizers include amines, ureas, sulfur-containing compounds, phosphorus-containing compounds, chlorine-containing compounds or nitriles, or other nitrogen-containing compounds, and the like. .
[0078]
In the production of an optical article using the ionizing radiation curable resin composition for an optical article of the present invention, energy rays such as ultraviolet rays are irradiated through a transparent substrate surface (sheet-like transparent resin layer (C)) serving as a support. Therefore, the photoinitiator that can be used is preferably an initiator having a light absorption ability in a long wavelength region, and a photoinitiator having a photoinitiation ability in a wavelength range of 360 to 450 nm, particularly in a wavelength range of 400 to 440 nm. Those that absorb light having a wavelength greater than 450 nm are poor in stability of the composition and need to be manufactured in a completely light-shielded environment, which makes it extremely difficult to handle.
[0079]
Examples of the initiator having absorption and initiation ability at the wavelength of light include 2,4,6-trimethylbenzoyldiphenoylphosphine oxide, thioxanthone and substituted thioxanthones, 2-benzyl-2-dimethylamino-1- (4 -Morpholinophenyl) -butanone-1,2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one and the like. In addition, when using an electron beam, these photoinitiators and photosensitizers are unnecessary.
[0080]
A lens array sheet, which is one of the optical articles of the present invention, is formed by applying the ionizing radiation curable resin composition layer (A) to a concavo-convex pattern of a matrix having a desired fine shape and filling it with ionizing radiation. After the curable resin layer is cured by ionizing radiation irradiation, it is peeled off from the mother mold and manufactured as a lens array sheet in which the fine structure of the mother mold is copied.
[0081]
At that time, it is preferable to irradiate with ionizing radiation in a state where a sheet-like transparent resin layer (C) is further adhered to one surface of the composition (A) coated and filled on the surface of the matrix. If the sheet-like transparent resin layer (C) is unnecessary for the final product, it is peeled off after the curing step.
[0082]
The adhesive layer (B) is not necessarily essential, depending on the degree of adhesion between the ionizing radiation curable resin composition layer (A) and the sheet-like transparent resin layer (C) and the required performance of the optical article. If necessary, it is formed between the sheet-like transparent resin layer (C) and the ionizing radiation curable resin composition layer (A).
[0083]
The sheet-like transparent resin layer (C) mentioned here is used for the purpose of imparting the physical strength of the lens array sheet and for obtaining the smoothness of the opposite surface of the matrix having a fine structure. In order to obtain such a smooth surface even when such a sheet-like transparent resin layer (C) is not used for the finished lens array sheet, the ionizing radiation curable resin composition layer (A) is used as a matrix and a sheet. It is preferable to cure in a state of being sandwiched between the transparent resin layer (C) and then peel and remove the transparent resin layer (C).
[0084]
In particular, when ultraviolet rays are used as ionizing radiation, the sheet-like transparent resin layer (C) is preferable because it can prevent inhibition of curing due to oxygen in the air. Furthermore, you may perform a well-known mold release process as needed to the side which contacts the ionizing radiation curable resin composition layer (A) of a sheet-like transparent resin layer (C).
[0085]
On the other hand, without the sheet-like transparent resin layer (C), it is conceivable to increase the film thickness of the ionizing radiation curable resin layer and increase the strength of the lens array sheet, but the film thickness of the ionizing radiation curable resin layer is large. If it becomes, it will become easy to produce the nonuniformity of the hardening degree in a film thickness direction, and hardening distortion. Therefore, integrating the sheet-like transparent resin layer (C) and the ionizing radiation curable resin layer (A) is a preferable method from the viewpoint of the production and strength of the lens array sheet.
[0086]
Such a sheet-like transparent resin layer (C) has mechanical strength such as breaking strength and tensile strength against physical impact, and has a uniform film thickness, smoothness, transparency, flexibility, It is necessary to have durability.
[0087]
Specifically, the transparent resin layer (C) is preferably in the form of a sheet, particularly preferably about 20 μm to 1 mm, and particularly preferably 50 to 150 μm from the viewpoint of processability, film properties, and transparency. It is. In addition, when the surface of the transparent resin layer (C) is a final product with the layer (C) and the layer (A) being in contact with each other, in order to improve the adhesion with the ionizing radiation curable resin layer (A), It may be subjected to easy adhesion treatment such as corona discharge treatment, plasma treatment, and easy adhesion primer coating.
[0088]
Specifically, a polyester sheet such as biaxially stretched polyethylene terephthalate having good transparency, an acrylic sheet such as polymethyl methacrylate, a polycarbonate sheet, a vinyl chloride sheet, and a polystyrene sheet can be used. In particular, from the viewpoint of durability, a polyethylene terephthalate or polycarbonate sheet is preferred.
[0089]
In the present invention, when a lens array sheet is formed as a laminate of a sheet-like transparent resin layer (C) and an ionizing radiation curable resin composition layer (A), the ionizing radiation curable resin layer (A) In addition to the durability of the sheet, the durability of the sheet-like transparent resin layer (C) as a base material, and the adhesion between the ionizing radiation-curing resin layer (A) and the sheet-like transparent resin layer (C) are also important. For this reason, an adhesive layer (B) can be provided between the sheet-like transparent resin layer (C) serving as the substrate and the ionizing radiation-curing resin layer (A).
[0090]
Specifically, the adhesive layer (B) comprises a cellulose resin (b1) and a polyisocyanate (b2), a polyester resin (b3) having a molecular weight of 3000 to 30000, and a polyisocyanate (b2). Comprising a polyester resin (b3) having a molecular weight of 3000 to 30000, an epoxy (meth) acrylate having a cyclic structure, and a photoinitiator, and the content of the epoxy (meth) acrylate is 10 to 60 wt. %.
[0091]
As the lens array sheet, a cured product layer (A) composed of an ionizing radiation curable resin composition for optical articles, an adhesive layer (B) composed of a cellulose resin (b1) and a polyisocyanate (b2), polyester or A lens array sheet comprising a sheet-like transparent resin layer (C) comprising a polycarbonate resin, a cured product layer (A) comprising a resin composition, a polyester resin (b3) having a molecular weight of 3000 to 30000, and a polyisocyanate A lens array sheet composed of an adhesive layer (B) composed of (b2) and a sheet-like transparent resin layer (C) composed of polyester or polycarbonate resin;
[0092]
A cured product layer (A) composed of a resin composition, a polyester resin (b3) having a molecular weight of 3000 to 30000, an epoxy (meth) acrylate having a cyclic structure, and a photoinitiator, and an epoxy (meth) acrylate And a lens array sheet comprising an adhesive layer (B) composed of a resin composition having a content of 10 to 60% by weight and a sheet-like transparent resin layer (C) composed of polyester or polycarbonate resin.
[0093]
However, the adhesiveness between the transparent resin layer (C) serving as the substrate sheet and the ionizing radiation curable resin layer (A) is sufficient, or corona discharge treatment or plasma treatment on the surface of the transparent resin layer (C). The adhesive layer (B) is not necessary when the adhesion is sufficient by an easy adhesion treatment such as an easy adhesion primer coat. Moreover, an easy-adhesion process and an adhesive bond layer (B) can also be used together in order to make adhesiveness stronger.
[0094]
The adhesive layer (B) must be selected from those having excellent adhesive ability for both the transparent resin layer (C) serving as a support and the ionizing radiation curable resin layer (A) forming a fine structure. Don't be. As the adhesive layer (B) of the present invention, a resin composition comprising a thermoplastic resin and a polyisocyanate (b2), a resin composition of a thermoplastic resin and an acrylate compound, or a polyisocyanate (b2) and a polyester (b3). The product has excellent adhesion and is particularly preferably used.
[0095]
As the thermoplastic resin referred to herein, known and commonly used ones can be used, but preferably, cellulose resins (b1) such as various cellulose esters and cellulose ethers, acrylic lacquers that are various (meth) acrylic acid ester polymers, and the like. Acrylic resins, polyester resins such as high molecular weight oil-free polyester, polycarbonate resins, polyester and polyether polyurethanes, and the like. Of these, cellulose resin (b1) and polyester resin (b3) are particularly preferable.
[0096]
Cellulose ester resin as used herein is one in which hydroxyl groups in cellulose are partially esterified with acids, and one or more acids such as nitric acid, sulfuric acid, acetic acid, propionic acid, butyric acid, other higher fatty acids and the like. It can be obtained by esterification. In particular, a cellulose ester resin esterified with acetic acid, propionic acid, or butyric acid is preferably used. Cellulose ether resin can also be used similarly to cellulose ester resin. A cellulose resin having an ester and ether bond is also preferably used.
[0097]
The polyester resin (b3) referred to here is a conventional one obtained by esterification reaction or transesterification reaction of a saturated or unsaturated polyol with a polybasic acid or a lower alkyl ester, and has a molecular weight of 3,000. ~ 30,000. As such a polyol raw material, known and commonly used ones can be used. Among them, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol,
[0098]
1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, 2,2,4-trimethyl-1,3-pentanediol, 3-methyl-1,5-pentanediol, dichloroneopentyl glycol, dibromoneopentyl glycol, hydroxypivalic acid neopentyl glycol ester, cyclohexane dimethylol,
[0099]
1,4-cyclohexanediol, trimethylolethane, trimethylolpropane, glycerin, 3-methylpentane-1,3,5-triol, pentaerythritol, dipentaerythritol, tripentaerythritol, spiroglycol, tricyclodecane dimethylol Hydrogenated bisphenol A and the like.
[0100]
Furthermore, as the polybasic acid compound, various known and commonly used carboxylic acids, or acid anhydrides thereof, and esterified products of these carboxylic acid compounds and lower alkyl alcohols can be used. Examples are maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, hetic acid, hymic acid, chlorendic acid, dimer acid, adipic acid, succinic acid, alkenyl succinic acid, sebatin. Acid, azelaic acid,
[0101]
2,2,4-trimethyladipic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, 2-sodium sulfoterephthalic acid, 2-potassium sulfoterephthalic acid, isophthalic acid, 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid Acid or di-lower alkyl esters of 5-sodium-sulfoisophthalic acid, such as dimethyl- or diethyl ester, or orthophthalic acid, 4-sulfophthalic acid, 1,10-decamethylene dicarboxylic acid,
[0102]
Muconic acid, oxalic acid, malonic acid, glutaric acid, trimellitic acid, hexahydrophthalic acid, tetrabromphthalic acid, methylcyclohexenticarboxylic acid or pyromellitic acid, or acid anhydrides thereof, or alcohols such as methanol and ethanol An ester compound etc. are mentioned.
[0103]
Moreover, as (meth) acrylic acid ester here, a well-known and usual thing can be used, More specifically, alkyl (meth) acrylates, such as methyl (meth) acrylate and ethyl (meth) acrylate, and cyclic Examples thereof include (meth) acrylate having a structure, polyoxyalkylene (meth) acrylate, and the like.
[0104]
Furthermore, as cyclic ester compounds, γ-butyrolactone, γ-valerolactone, δ-valerolactone, ε-caprolactone, D-glucono-1,4-lactone, 1,10-phenanthrenecarbolactone, 4-pentene-5 Lactones such as orido and 12-dodecanolide are exemplified.
[0105]
As acrylate compounds that can be preferably used for the adhesive layer, those that are usually used as reactive diluents, various acrylate oligomers, and acrylate polymers can be used. Examples of these acrylate compounds include epoxy acrylate and urethane acrylate. A sheet, polyester acrylate, polyether acrylate or the like can be used alone or in combination of two or more.
[0106]
Among these, an epoxy acrylate compound is particularly preferable from the viewpoint of adhesion to an ionizing radiation curable resin layer having a fine pattern. As the epoxy acrylate used here, those exemplified in the above-mentioned ionizing radiation curable resin composition can be used, and these acrylate compounds are preferably 10 to 60% by weight in the adhesive layer resin. .
[0107]
When the acrylate compound is less than 10% by weight, the adhesion with the ionizing radiation curable resin layer which is the upper layer of the adhesive layer is lowered, or a phenomenon such as whitening is observed in the water resistance test. On the other hand, when the amount of the acrylate compound is more than 60% by weight, an adverse effect of reducing the adhesion to the base material tends to occur.
[0108]
Polyester or polyether-based polyurethane can be obtained by reacting a polyester polyol having a molecular weight of about 500 to 4000, or a polyisocyanate such as polyethylene glycol, polypropylene glycol or polytetramethylene glycol with polyisocyanate. Can be used.
[0109]
Of course, the polyisocyanate used here may be used alone or in combination with an isocyanurate-formed polyisocyanate and an isocyanate compound. Any isocyanate can be used, but to name only representative ones, such as tolylene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, Various alicyclic diisocyanate compounds,
[0110]
Alternatively, various compounds such as various aliphatic diisocyanate compounds such as hexamethylene diisocyanate or lysine diisocyanate can be used. Further, isocyanates obtained by converting the above isocyanate monomers into burettes, allophanates, isocyanurates, and polyisocyanates obtained by reaction with polyols can also be used. These may be used alone or in combination. Among these, a polyisocyanate compound having three or more isocyanate groups in the molecule is preferable, and a polyisocyanate derived from hexamethylene diisocyanate is particularly preferable.
[0111]
The ratio of the thermoplastic resin to the polyisocyanate is such that the hydroxyl equivalent of the thermoplastic resin and the isocyanate equivalent of the polyisocyanate, the OH equivalent / NCO equivalent ratio is in the range of 0.1 to 5, preferably 0.1. In the range of ˜1, it is desirable in terms of adhesive reliability. Moreover, as a film thickness of an adhesive bond layer (B), the range of 0.2-10 micrometers is suitable.
[0112]
The adhesive layer (B) is applied to the sheet-like transparent resin layer (C), and if necessary, a setting time is provided or the temperature is increased to evaporate the solvent and the like. Thereafter, the ionizing radiation curable resin layer (A) is applied, and a matrix having a desired fine shape is adhered, and the ionizing radiation curable resin layer is cured with ionizing radiation in this state, whereby the sheet and the ionizing radiation curable resin are cured. Adhesion of layers can be obtained.
[0113]
In addition, it is preferable to add a photo (polymerization) initiator to the adhesive layer (B), particularly a resin composition system of a thermoplastic resin and an acrylate compound, from the viewpoint of increasing the reactivity of the adhesive layer. The photoinitiators described above can be used.
[0114]
As a method for producing a lens array sheet, which is one of optical articles using the ionizing radiation curable resin composition of the present invention, various known production methods can be applied and are not particularly limited. A manufacturing method as disclosed in Japanese Patent No. 3687346, US Pat. No. 4,576,850, Japanese Patent Publication No. 63-50066, Japanese Patent Application Laid-Open No. 5-169015 and the like is used. Next, an outline of a method for manufacturing a lens array sheet will be described with reference to FIG.
[0115]
In FIG. 4, 1 is a roll intaglio in which desired irregularities are formed, 2 is a recess of the roll intaglio 1, 3 is an uncured ionizing radiation curable resin liquid, 3a is a cured ionizing radiation curable resin, 4 is necessary According to the transparent base sheet (C) with an adhesive layer (B), 5 is a pressing roll that presses the roll intaglio 1, 6 and 8 are feed rolls, 7 is an ionizing radiation irradiation device, and 9 is the purpose. The lens array sheet 10 is a T-die nozzle, 11 is a drying device, and 12 is a liquid reservoir.
[0116]
As a method for filling the concave portion 2 of the roll intaglio 1 with the ionizing radiation curable resin 3, as shown in FIG. 4, a predetermined amount of ionizing radiation curable resin liquid 3 is applied to the surface of the roll intaglio 1 in advance. In this case, when the base sheet 4 is supplied to the roll intaglio 1, the ionizing radiation curable resin liquid 3 is applied through the base sheet 4 by pressing from the back side of the base of the pressing roll 5. Is distributed and filled in the recess 2.
[0117]
In this case, a solvent-type curable resin can be used, and the solvent can be volatilized and removed by the drying device 11. The number of ionizing radiation irradiation devices 7 may be one as shown in FIG. 4, but a plurality of curing devices may be provided to cure the resin liquid 3 in the roll intaglio 1 in multiple stages. In this way, a sufficient irradiation amount can be obtained even if the traveling speed of the base sheet 4 is increased, and by gradually curing, the curing strain of the resin liquid 3 and the curl and strain of the base sheet 4 can be obtained. Is preferable in order to reduce.
[0118]
Next, while the substrate sheet 4 is in contact with the roll intaglio 1 (specifically, when it is located between the pressing roll 5 and the feed roll 6 in the figure), the ionizing radiation irradiation device 7 ionizes the sheet. The radiation curable resin 3 is cured. When the ionizing radiation irradiation device 7 irradiates the ionizing radiation, it is performed from the base sheet 4 side. The roll intaglio is formed of a material having good ionizing radiation permeability such as quartz or glass, and the roll intaglio is formed. It is also possible to irradiate from the inner side of 1 (specifically, it is performed by an irradiation device installed in the roll hollow). Moreover, you may irradiate from a base material sheet side, an intaglio internal side, and both surfaces.
[0119]
The ionizing radiation curable resin 3 in the recess 2 of the roll intaglio 1 is cured and adhered to the base sheet 4 by the ionizing radiation irradiation device 7. After passing through the ionizing radiation irradiation device 7, the base sheet 4 is peeled from the roll intaglio 1. As a result, the cured ionizing radiation curable resin liquid 3a is integrated with the base sheet 4 and is detached from the recess 2 to obtain a lens array sheet 9 having an uneven surface.
[0120]
In the manufacturing method as described above, the transparent base sheet 4 may be, for example, a polyester resin such as polyethylene terephthalate, polybutylene terephthalate, or polyethylene naphthalate, an acrylic resin such as polymethyl methacrylate, a polycarbonate resin, or a polystyrene resin. A sheet made of a thermoplastic resin or the like can be used. The thickness is determined from the viewpoint of workability such as device handling, but is usually about 10 to 1000 μm.
[0121]
In the final product stage, if a base sheet is not required, a treatment (silicone) for imparting releasability to the cured product of the ionizing radiation curable resin in advance on the surface of the base sheet having the lens array The substrate sheet may be peeled off from the lens array sheet after the above-described production method is completed.
[0122]
The ionizing radiation of the ionizing radiation irradiation device means an electromagnetic wave or a charged particle beam having an energy quantum capable of polymerizing and cross-linking molecules. Usually, ultraviolet rays, electron beams, etc. are used. A light source such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a black light lamp, or a metal halide lamp can be used. As the ultraviolet wavelength, a wavelength range of 1900 to 3800 angstroms is mainly used.
[0123]
In the case of an electron beam, it is equipped with an irradiation source such as a cockroft Walton type, a bandegraph type, a resonant transformer type, an insulated core transformer type, or various electron beam accelerators such as a linear type, a dynamitron type, and a high frequency type. An electron having an energy of 100 to 1000 KeV, preferably 100 to 300 KeV is irradiated. As an irradiation dose, about 0.5-30 Mrad is preferable normally.
[0124]
The solvent drying apparatus 11 in FIG. 4 is an apparatus for volatilizing the resin solvent. As the solvent drying device 11, warm air, an infrared heater, or the like can be used. Note that when the solventless ionizing radiation curable resin is used, the drying device 11 is unnecessary.
[0125]
Next, as a specific example of the optical article of the present invention, a typical shape of a lens array sheet formed by forming a lens array in which unit lenses made of a cured product of ionizing radiation curable resin are arrayed in a one-dimensional or two-dimensional direction. The perspective view which shows is shown in FIGS.
[0126]
In FIG. 5, a triangular prism (lens) is used as the unit lens 41, and a large number of the unit lenses are arranged in a one-dimensional direction (direction perpendicular to the ridge line) so that the ridge line directions thereof are parallel to each other on a plane. This is a so-called triangular prism linear array sheet, which is a lens array sheet 9. The apex angle β is typically about 60 ° to 120 °, and the repetition period P is typically 20 to 500 μm.
[0127]
6 uses a semi-cylindrical or semi-ellipsoidal convex lens as the unit lens 41, and a large number of the unit lenses are arranged in a one-dimensional direction (a direction perpendicular to the ridge line) so that the ridge line directions are adjacent to each other. The lens array sheet 9 is a so-called lenticular lens. FIG. 7 is a diagram in which the unit lens is replaced with a concave lens in FIG. 6 and should also be called a concave lens lenticular lens.
[0128]
FIG. 8 shows a so-called eyelet lens in which a hemisphere or a semi-spheroid is used as a unit lens, and a plurality of unit lenses are arranged in a two-dimensional direction to form a lens array sheet 9. FIG. 9 shows a lens array sheet 9 in which a quadrangular pyramid is used as a unit lens and a large number of the unit lenses are arranged in a two-dimensional direction.
[0129]
However, FIGS. 5 to 9 are only examples of the lens arrangement sheet, and the lens arrangement sheet of the present invention is not limited to these. For example, the following are also included in the optical article of the present invention.
(1) Individual unit lenses having different shapes, such as Fresnel lenses, or non-periodic arrangement of unit lenses (On the other hand, the lenses in FIGS. It is also possible to have a periodic arrangement.
[0130]
(2) The unit lens may be either a convex lens or a concave lens, or may be a combined arrangement of a concave lens and a convex lens.
(3) Furthermore, the concept of a lens in the present invention is a generic term for elements that modulate and control light such as condensing, deflecting, and diffusing transmitted light by refracting transmitted light or reflecting it on the inner surface. , Diffraction gratings, holograms, and the like.
[0131]
(4) The lens array sheet of the present invention may be used alone as shown in FIGS. 5 to 9 or may be used by stacking two or more as shown in FIG. 10 if necessary. . For example, as shown in FIG. 10, when two lens array sheets are laminated so that their ridge lines are perpendicular to each other, transmitted light can be controlled and modulated in both the X and Y directions.
[0132]
(5) The lens array sheet 9 of the present invention may have a single-layer structure made of a cured product of an ionizing radiation curable resin composition as shown in FIGS. 5, 7, 8, and 9, or FIG. A two-layer structure in which a lens array (41) is formed on the surface of a transparent substrate sheet (including plates and films) 4 as shown in FIG.
[0133]
(6) The lens array sheet of the present invention may have a lens array on both sides of the sheet in addition to the lens array on one side of the sheet as shown in FIGS.
[0134]
As a mother mold having a fine shape of the lens arrangement sheet, a mold providing a Fresnel lens, a lenticular lens, a fly-eye lens, or a modification thereof, for example, a polygonal pyramid, a truncated cone, or an identical polygonal truncated cone A shape in which a large number of isotropic shapes of the same body type are arranged on a plane can be formed. Here, when a regular triangular pyramid (or frustum), a regular quadrangular pyramid (or frustum), or a regular hexagonal pyramid (or frustum) is used as a pyramid or a truncated pyramid, it can be arranged without gaps in a plane and isotropic in shape. It is possible to have the same half-value angle in both the horizontal and vertical directions, and it is preferable that there is no variation depending on the location.
[0135]
Alternatively, a metal or synthetic resin mold that is the same shape as the shape of the optical part, such as an array of a plurality of continuous trihedral prisms or tetrahedral prism elements, and a reverse irregularity shape is used. It is possible to use. Further, such a matrix can be manufactured even if it has a fine shape on a plane or a cylindrical surface.
[0136]
Next, the surface light source of the present invention will be described.
The surface light source of the present invention includes at least a light guide made of a translucent flat plate, a light source unit provided adjacent to at least one of the side end faces of the light guide, and the light guide. It is composed of a light reflecting layer provided on the back surface and one or two optical articles (lens array sheet) of the present invention laminated on the light emitting surface of the light guide body surface, and is generally an edge light type A so-called surface light source is a typical example.
[0137]
FIG. 11 shows a perspective view of an example of the surface light source of the present invention. At least a light source 51 and a linear or dotted light source 52 installed adjacent to at least one place on the side end surface thereof, a light reflecting layer 53 in contact with the light guide 51, and the optical article of the present invention ( Lens array sheet) 9. Usually, a lamp house 54 whose inner surface is a reflection surface is further provided around the light source 52.
[0138]
Usually, the light guide 51 uses a transparent plate of about 1 to 100 mm made of acrylic resin, polycarbonate resin, glass or the like. The transparent plate may have a uniform thickness over the entire surface. However, it is preferable to make the thickness thinner as the distance from the light source increases, so that the luminance of the output light becomes uniform regardless of the distance from the light source. As the light source 52, a fluorescent lamp such as a cold cathode tube is used as a line light source, and an incandescent bulb, a light emitting diode, or the like is used as a point light source.
[0139]
In order to diffusely reflect light, the light reflecting layer 53 is generally formed by forming a light diffusive dot pattern by printing with white ink or the like, and further depositing or plating a metal film on the back surface thereof. . In general, as the distance from the light source increases, the area ratio of the light diffusive and reflective dot pattern is increased, so that the amount of light emitted from the light exit surface is made uniform. In addition, a light diffusing transparent sheet may be arranged between the light guide 51 and the lens array sheet 9 to diffuse light uniformly and make the light diffusing dot pattern of the light reflecting layer 53 invisible.
[0140]
When the lens array sheet is mounted on the surface light source, a configuration in which the lens side is directed to the light guide plate side or the side opposite to the light guide plate (light exit surface side) is also possible. The number of lens arrangement sheets may be one, but in the case of a columnar lens, in order to control the light diffusion angle in two directions (vertical direction and horizontal direction), two lens arrangement sheets are used as shown in FIG. May be laminated so that the ridgelines of the unit lenses intersect (orthogonal in the figure).
[0141]
In this case, the orientation of the surface having the lens arrangement (hereinafter referred to as “lens surface”) is high in light transmission if both are the same, and the lens surface of the lower lens arrangement sheet and the upper lens arrangement sheet This is preferable because moire fringes with the minute protrusions on the back surface can be prevented. Further, the lens surfaces of the two lens array sheets may be opposed to face each other.
[0142]
The edge light type surface light source of the present invention is used for various applications, for example, a transmissive liquid crystal display element, a lighted advertising board, a signboard, a traffic sign, a light table for observing a photographic negative, a positive image, indoor lighting, etc. be able to. FIG. 12 is an example in which a transmissive liquid crystal display panel 60 is arranged on the surface light source 100 of FIG.
[0143]
The preferable performance of the surface light source is described in, for example, JP-A-5-169015 and other publicly known materials. However, the brightness of the display screen in the radial direction (normal luminance) is usually 1000 cd / cm.²As described above, the surface light source is usually preferably bright, and it is not necessary to set an upper limit for the normal luminance.
[0144]
In addition, televisions, word processors, liquid crystal display panels, etc. require a horizontal field of view, so there is little decrease in luminance due to diffusion of light from the normal direction, that is, normal direction luminance does not decrease over a wide range. It is preferable that the angle (half-value angle) at which the luminance is half of the normal luminance is wide. Usually, the half-value angle of the surface light source used for these uses is 30 to 90 degrees, preferably 45 to 90 degrees.
[0145]
【Example】
Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention should not be limited to these. All parts and percentages in the examples are based on weight unless otherwise specified.
[0146]
(Comparative Synthesis Example 1)
A flask equipped with a thermometer, a stirrer, and a condenser was charged with 524 parts of diphenylmethane diisocyanate and heated to 60 ° C. with stirring, and a ring-opening reaction product (OH value) of ε-caprolactone and 1,6-hexanediol. = 215 KOH-mg / g) 520 parts were added dropwise over 1 hour while paying attention to heat generation. The reaction was carried out for 10 hours, after which 232 parts of hydroxyethyl acrylate were added, and the reaction was further carried out for 10 hours. After confirming that the absorption of the isocyanate group disappeared by the infrared absorption spectrum, urethane acrylate (RSH-1) having a hard segment and a soft segment of Comparative Example was obtained.
[0147]
(Comparative Synthesis Example 2)
A flask equipped with a thermometer, a stirrer, and a condenser was charged with 444 parts of isophorone diisocyanate and heated to 60 ° C. with stirring. Polyester diol of 1,6-hexanediol and adipic acid (OH value = 51 KOH− 2200 parts of mg / g) was dropped over 1 hour while paying attention to heat generation. The reaction was carried out for 10 hours, after which 232 parts of hydroxyethyl acrylate were added, and the reaction was further carried out for 10 hours.
[0148]
By confirming that the absorption of the isocyanate group disappeared by infrared absorption spectrum, 1917 parts of tripropylene glycol diacrylate was further added and completely dissolved, and urethane acrylate (RSH having a hard segment and a soft segment of Comparative Example) -2) was obtained.
[0149]
(Examples 1-4)
An ionizing radiation curable resin composition (A) for an optical sheet was prepared according to the formulation shown in Table 1.
[0150]
Next, using the apparatus shown in FIG. 4, a metal roll having the same shape and reverse irregularities on the surface as a retroreflective lens having a shape in which a plurality of regular tetrahedrons continuously arranged at a pitch of 50 μm are two-dimensionally arranged. While rotating the intaglio around the axis, the ionizing radiation curable resin composition (A) is applied to the roll surface from a T-die nozzle, and the sheet-like transparent resin is synchronized with the peripheral speed of the roll intaglio. While running the layer (C) (transparent PET film: single-sided corona discharge treatment), the corona discharge treatment surface of the transparent PET film and the roll intaglio surface are interposed with the ionizing radiation curable resin composition (A) in between. Then, two high-pressure mercury lamps (160 W / cm) were irradiated from the position of 10 cm as they were from the PET film side, and the resin layer was cured and simultaneously adhered to the PET film.
[0151]
At this time, the irradiation amount of ultraviolet rays irradiated on the surface of the PET film is 500 mj / cm.²Met. After curing, the PET film was peeled off from the roll intaglio together with the ionizing radiation curable resin layer to produce a continuous sheet of optical sheet on which the desired shape of the roll intaglio was transferred. As physical property evaluation of the optical sheet and the cured resin, tests such as placement marks, curls, and adhesion were performed.
[0152]
In addition, the prepared resin compositions of the examples were applied on a clean and smooth glass plate to a thickness of 60 to 70 μm, and ultraviolet rays were applied at 500 mj / cm with a high-pressure mercury lamp (160 W / cm).²Irradiated to produce a cured test piece. About this hardened | cured material, evaluation, such as a tensile test and curability, was performed. These results are shown in Table 3.
[0153]
(Comparative Examples 1 and 2)
An ionizing radiation curable resin composition for a comparative optical sheet was prepared according to the formulation shown in Table 2. About this, the hardened | cured material for physical property test and the lens arrangement | sequence sheet | seat were produced similarly to Examples 1-4. Table 3 shows the results of comparative evaluation of the cured products for physical property testing as in Examples 1 to 4. Table 5 shows the evaluation results of the lens array sheet.
[0154]
(Examples 5 and 6)
As the sheet-like transparent resin layer (C), a transparent PET film (film thickness 100 μm) was used, and the adhesive layer (B) was applied thereon with a roll coater so as to have a dry film thickness of about 1 μm. At this time, the solvent contained in the adhesive layer composition was dried by heat treatment at 80 ° C. for 30 seconds. The resin composition of the adhesive layer (B) is shown below.
[0155]
In Example 5, the composition of Example 1 was used as the ultraviolet curable resin layer, and in Example 6, the composition of Example 3 was used as the ultraviolet curable resin layer. A lens array sheet was manufactured in exactly the same manner except that a PET film coated with an adhesive layer (B) was used instead of the sheet-like transparent resin layer (C) (transparent PET film: single-sided corona discharge treatment). did. The ultraviolet curable resin layer was produced so as to be on the adhesive layer (B). The evaluation results of these lens array sheets are shown in Table 5.
[0156]
(Resin composition of adhesive layer (B) of Example 5)
10 parts high molecular weight oil-free polyester resin (terephthalic acid, isophthalic acid, adipic acid, ethylene glycol, 1,6-hexanediol, neopentyl glycol condensate, molecular weight about 5000), 2 parts bisphenol A epoxy acrylate 4 parts of toluene and 4 parts of butyl acetate for a total of 20 parts.
[0157]
(Resin composition of adhesive layer (B) of Example 6)
Cellulose acetate butyrate resin (Butylation degree 37%, Acetylation degree 13%, Residual hydroxyl group 2%) 15 parts, Toluene 40 parts, Methyl ethyl ketone 40 parts, Trimethylene propane adduct type polyisocyanate (NCO% = 16.7%) 5 parts, for a total of 100 parts.
[0158]
(Measurement and evaluation method)
The measurement / evaluation method is described below.
(1) Viscosity
An E-type rotational viscometer was used to measure viscosity (cps) at 25 ° C.
[0159]
(2) Refractive index
Liquid samples and cured samples were measured. The liquid sample was directly applied to the prism of the Abbe refractometer and measured at 25 ° C. Moreover, the cured resin layer was peeled off from the glass plate on the glass plate, and it was set as the sample. 1-Bromonaphthalene was used as an intermediate solution for bringing the sample into close contact with the prism, and measurement was performed with an Abbe refractometer at a sample temperature of 25 ° C. Table 6 shows the measurement results.
[0160]
(3) Tensile test (breaking strength, breaking elongation, tensile modulus, σ2 / σ1, and SS pattern)
The sheet of the cured product was punched out using a dumbbell super dumbbell (JIS 7113 No. 2 dumbbell) to obtain a measurement sheet, and the breaking strength, breaking elongation, and tensile modulus were measured. However, at the time of measurement, for the purpose of preventing the measurement sheet from slipping on the chuck, the left and right and top and bottom four places outside the marked line (25 mm) are a steel plate and adhesive (Toa Gosei Chemical Co., Ltd.) with a thickness of 0.3 mm and a length and width of 20 mm It was fixed using Aron Alpha) and used as a grip part.
[0161]
The tester used Tensilon made by Toyo Baldwin Co., Ltd., and the deformation rate was 1.0 mm / min.
Tensile strength, elongation at break, and tensile modulus: Tensile tests were conducted in the same manner as the rigidity, and the stress and elongation at the time when the measurement sheet broke were measured to be the strength at break and elongation at break, respectively. Further, the tensile elastic modulus was calculated from the slope obtained by drawing the tangent line of the SS curve (stress-strain curve) from the starting point of tensile deformation. However, the number of measurements was 5, and the average value is shown in the table as the evaluation result.
[0162]
σ2 / σ1 (elasticity evaluation): σ2 / σ1 was read from the SS curve of the pattern as shown in FIG. 3 obtained above, and σ2 / σ1 was calculated.
Pattern evaluation of SS curve: Similarly, from each SS curve, a pattern having no yield point as shown in FIG. 1 is shown as A, and a pattern having a yield point as shown in FIG. It was described in.
[0163]
(4) Place mark
A PET adhesive tape with a thickness of 75 μm and 1 inch square is placed in the center on a smooth iron plate, and on that, 60 sheets of the lens array sheet that has been cut out are 10 cm × 10 cm, and the UV curable resin layer is on top. Superimposed. Furthermore, 500g / cm from above²The load was applied. After leaving for 3 days with a load applied at a temperature of 40 ° C, the load is removed, each lens array sheet is visually checked with a fluorescent lamp or by reflected light, and the presence or absence of a placement mark is confirmed. The number of sheets from the adhesive tape was confirmed.
[0164]
○: No trace of placement marks is confirmed on the 21st and subsequent sheets from the adhesive tape.
×: Placement marks can be confirmed on the 21st and subsequent sheets from the adhesive tape.
[0165]
(5) Light transmittance
A test piece having a thickness of 0.4 mm was prepared, the light transmittance in the wavelength region of 400 to 900 nm was measured, and the one showing a transmittance of 90% or more in all regions was set as “O” (pass), and the transmittance was less than that. The thing was made into x (failed).
[0166]
(6) Pencil hardness
Measurement was performed in accordance with JIS K-5400. H or higher was evaluated as ◯ (passed), and F or lower was evaluated as x (failed).
[0167]
(7) Curing shrinkage
The ionizing radiation curable resin compositions of Examples and Comparative Examples were each placed in a stainless steel pan having an inner diameter of 30 mm and a height of 10 mm up to a height of about 5 mm, and a high pressure mercury lamp (80 W / cm) conveyor type ultraviolet irradiation device was used. 1000mj / cm under air atmosphere²The cured product for specific gravity measurement was prepared by irradiating with ultraviolet rays.
[0168]
The specific gravity (DS) of the cured product was measured at 23 ± 2 ° C. in accordance with JIS K-7112 B method. However, distilled water was used as the immersion liquid, the specific gravity (DL) of the resin composition was measured at 23 ± 2 ° C., and the cure shrinkage rate was calculated by the following formula. For the measurement results, the average value of the two measurement results was calculated, and when it was 5.5% or less, it was evaluated as ◯ (pass), and when it was more than that, it was determined as x (fail).
Curing shrinkage (%) = [(DS-DL) / DS] × 100
[0169]
(8) Curl property
Cut out the created lens array sheet to A4 size, leave the sheet forming surface up on a horizontal plane, measure the height (mm) that the edge of the optical sheet naturally curled from the horizontal plane, and curled the height Was 1 (mm) or less when it was 1 mm or less, and x (failed) when it was more than that.
[0170]
(9) Initial adhesion
The adhesion between the transparent PET substrate and the ionizing radiation curable resin layer forming the optical sheet layer was measured according to JIS K-5400. The time when 95/100 or more of the mesh remained was defined as ◯ (passed), and the time less than that was defined as x (failed).
[0171]
(10) Curability
When irradiated with a 160 W / cm high-pressure mercury lamp at a lamp height of 15 cm and a line speed of 10 m / min, the number of irradiation until the surface tack free was measured. When the number of times of irradiation is smaller, the curability is better, and those that become tack-free in 2 passes or less are evaluated as ◯ (pass), and those that require more irradiation are determined as x (failed).
[0172]
(11) Plate separation
After UV curing, the PET film is peeled from the roll intaglio together with the ionizing radiation curable resin layer, and when producing a lens array continuous sheet to which the desired shape of the roll intaglio is transferred, there is no significant load at the time of peeling. (Accepted), a thing that could cause a crease or the like in the sheet due to a large peeling sound or load at the time of peeling was defined as x (failed).
[0173]
(12) Initial appearance
The appearance after the optical sheet was manufactured was visually determined. Judgment criteria are ○ (acceptable) when a uniform lens surface shape was obtained, △ (slightly rejected) when cracks or omissions were observed in part, and cracks or omissions in shape over the entire surface. What was seen was made into x (failed).
[0174]
(13) Boiling water adhesion
The prepared optical lens sheet was immersed in boiling water at 95 ° C. or higher for 4 hours, taken out to room temperature, and the adhesion after 2 hours was measured according to JIS K-5400. The numbers indicate the number of remaining contact pieces, 100 indicates that all the square pieces (100 pieces) remain, and 0 indicates that all the pieces are peeled off.
[0175]
(14) Appearance after boiling water
The prepared optical lens sheet was immersed in boiling water at 95 ° C. or higher for 4 hours, taken out to room temperature, and the appearance coating film state was visually evaluated.
[0176]
(15) Accelerated weather resistance adhesion
The prepared optical lens sheet was subjected to an accelerated weathering test for 400 hours with a fade meter (Suga test machine: black panel temperature: 63 ± 3 ° C.), and the adhesion was measured according to JIS K-5400. The numbers represent the number of remaining adhesive pieces as in (13) boiling water adhesion.
[0177]
Abbreviations of resins used in Examples and Comparative Examples are shown below.
BBA: Tetrabromobisphenol A type epoxy acrylate
BBF: Tetrabromobisphenol F type epoxy acrylate
BA: Bisphenol A type epoxy acrylate
[0178]
PIPA: 2-phenyl-2- (4-acryloyloxyethoxyphenyl) propane
BPOEA: 2,4,6-tribromophenylethoxy acrylate
[0179]
THFA: Tetrahydrofurfuryl acrylate
PGA: 2-hydroxy-3-phenoxy-propyl acrylate
(Phenyl glycidyl ether acrylate)
# 184: 1-hydroxycyclohexyl phenyl ketone
d1173: 2-hydroxy-2-methyl-1-phenylpropan-1-one
[0180]
In the table, (a) is an epoxy (meth) acrylate having a cyclic structure and having two or more acrylate groups, (b) is a monofunctional (meth) acrylate having a cyclic structure, (c ) Represents a photopolymerization initiator. Furthermore, RSH1 and RSH2 in the table are urethane acrylates synthesized in Comparative Synthesis Examples 1 and 2.
[0181]
The unit of the evaluation result in the table is shown below.
Viscosity: 1000 cps / 25 ° C
DB concentration: concentration of (meth) acrylate functional group in resin composition (mmol / g)
Breaking strength: Kg / cm²
Elongation at break:%
[0182]
Elastic modulus (tensile modulus): 100 Kg / cm²
σ2 / σ1: Elasticity evaluation
SS: SS curve pattern evaluation
Place mark: (4) Evaluation with place mark
Light transmission: (5) Evaluation by light transmittance
[0183]
Hardness: (6) Evaluation with pencil hardness
Shrinkage rate: (7) Evaluation by curing shrinkage rate
Curl: (8) Evaluation by curl properties
Adhesion: (9) Evaluation by initial adhesion
Curability: (10) Evaluation by curability
Refractive index: (2) Liquid refractive index and cured product refractive index at 25 ° C. by refractive index.
[0184]
13 and 14 show tensile stresses (kg / cm) of the cured resin compositions obtained in Example 1 and Example 3, respectively.²) And strain (%). These are shown as an example of the SS curve of an Example. No yield point was found in the SS curves of all examples.
[0185]
FIG. 15 shows the tensile stress (kg / cm of the cured resin composition obtained in Comparative Example 1.²) And strain (%). An obvious yield point is observed. Further, σ2 and σ1 were not particularly shown, but the measured (σ2 / σ1) is shown in the table.
[0186]
(Examples 7 to 10) Creation of surface light source
Using the lens array sheets prepared in Examples 1 to 4, edge light type surface light sources as shown in FIG. 11 were prepared, and the performance as a surface light source was evaluated.
(Light guide plate)
The thickness is 4mm, the area is 9.4 inches diagonal, and the material is transparent acrylic resin.
[0187]
(Plate light diffuse reflection layer)
Using a white ink (using titanium oxide pigment) on the back surface of the light guide plate, a dotted pattern was printed, and on the back surface, an aluminum-deposited PET film was laminated to form a specular reflection layer. The area ratio of the scattered dot pattern was increased as the distance from the light source was increased. In addition, since it is a 2 square type, it was made for the area ratio of a scattered dot pattern to become the maximum in the center.
[0188]
(light source)
Two cold cathode fluorescent lamps (power consumption 4 W) each having a diameter of 3 mm, one on each side of the light guide plate, were installed, and the portions other than the side facing the light guide plate were covered with a reflecting mirror.
(Light diffusion transparency sheet)
A stack of two 38 mm thick sandblasted PET sheets was used.
[0189]
The produced surface light source was measured for luminance with a luminance meter (Topcon BM-8) at a position 30 cm from the light exit surface (the surface of the lens array sheet). The measurement was performed in the range of −90 ° to + 90 ° with the normal direction (0 ° direction) of the light exit surface as the center, and the angle dependency (light distribution characteristic, half-value angle) was also measured. Furthermore, it was confirmed by visual observation whether the placement mark can be recognized as a luminance distribution or change.
[0190]
As a result of the measurement, all of the created surface light sources had a normal luminance of 1200 cd / cm.²Or more (1200 to 1250 cd / cm²In addition, both the half-value angles were 65 ° or more (65 ° to 75 °), and no luminance change derived from the placement marks was observed, and a good surface light source could be created.
[0191]
[Table 1]

[0192]
[Table 2]

[0193]
[Table 3]

[0194]
[Table 4]

[0195]
[Table 5]

[0196]
【The invention's effect】
The present invention has an excellent ionizing radiation curable resin composition for optical articles, which has high surface hardness and refractive index, and has no problems of shrinkage deformation at the time of curing, deformation and marking after curing, and deterioration in weather resistance, An excellent optical article and a surface light source using a cured product can be provided.
[Brief description of the drawings]
[Fig. 1] Tensile stress (kg / cm²) And strain (%) is a schematic diagram showing a relationship (SS curve). The vertical axis represents tensile stress (kg / cm²), The horizontal axis represents strain (%). (Pattern with no yield point. Pattern A)
FIG. 2 shows tensile stress (kg / cm²) And strain (%) (S-S curve). The vertical axis represents tensile stress (kg / cm²), The horizontal axis represents strain (%). (This is a pattern where the yield point can be seen. Pattern B)
FIG. 3 shows tensile stress (kg / cm²) And strain (%) is a schematic diagram showing a relationship (SS curve). The vertical axis represents tensile stress (kg / cm²), The horizontal axis represents strain (%). (Pattern with no yield point. Pattern A)
FIG. 4 is a diagram illustrating an example of a continuous manufacturing method of a lens array sheet according to the present invention.
FIG. 5 is a diagram schematically showing an example of a lens array sheet according to the present invention.
FIG. 6 is a diagram schematically showing an example of a lens array sheet according to the present invention.
FIG. 7 is a diagram schematically showing an example of a lens array sheet according to the present invention.
FIG. 8 is a diagram schematically showing an example of a lens array sheet according to the present invention.
FIG. 9 is a diagram schematically showing an example of a lens array sheet according to the present invention.
FIG. 10 is a diagram schematically showing an example of a lens array sheet according to the present invention.
FIG. 11 is a diagram showing an example of a surface light source according to the present invention.
FIG. 12 is a diagram showing an example of a surface light source according to the present invention.
13 is a tensile stress (kg / cm) of the cured resin composition obtained in Example 1. FIG.²) And strain (%).
14 is a tensile stress (kg / cm) of the cured resin composition obtained in Example 3. FIG.²) And strain (%).
15 is a tensile stress (kg / cm) of a cured resin composition obtained in Comparative Example 1. FIG.²) And strain (%).
[Explanation of symbols]
1 Roll intaglio
2 recess
3 Uncured ionizing radiation curable resin composition (A)
3a Cured ionizing radiation curable resin composition (A)
4 Base sheet (C)
5 Pressing roll
6 Feeding roll
7 Curing equipment
8 Feeding roll
9 Lens arrangement sheet
10 T-die nozzle
11 Drying equipment
12 Liquid reservoir
P Repeat cycle
β apex angle
41 unit lens
51 Light guide
52 Light source
53 Light reflection layer
54 Lamphouse
60 Transmission type LCD panel
100 surface light source
200 Liquid crystal display (LCD)

Claims (8)

An epoxy (meth) acrylate (a) having a cyclic structure and having two or more (meth) acrylate groups, 2-hydroxy-3-phenoxy-propyl (meth) acrylate, 2-phenyl-2- [4- One selected from the group consisting of (meth) acryloyloxyphenyl] propane, 2-phenyl-2- [4- (meth) acryloyloxyalkoxyphenyl] propane, benzyl (meth) acrylate and (meth) acryloyloxyphthalic acid It consists of the monofunctional (meth) acrylate (b) which has the above cyclic structure, The compounding ratio of (b) is 20 to 70 weight%, (meth) acrylate functional group concentration is 0.2 to 5.0 mmol / g, and in the relationship diagram between tensile stress and strain, the cured product has no yield point, Manabu article for ionizing radiation curable resin composition. The monofunctional (meth) acrylate (b) having a cyclic structure is 2-phenyl-2- [4- (meth) acryloyloxyphenyl] propane and / or 2-phenyl-2- [4- (meth) acryloyloxyalkoxy. The ionizing radiation curable resin composition for optical articles according to claim 1, which is phenyl] propane. Bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol A type epoxy resin partially substituted with epoxy (meth) acrylate (a) having a cyclic structure and having two or more (meth) acrylate groups An epoxy (meth) acrylate obtained by reaction of one or more epoxy resins selected from the group consisting of partially halogen-substituted bisphenol F type epoxy resins and hydrogenated bisphenol A type epoxy resins with (meth) acrylic acid The ionizing radiation-curable resin composition for an optical article according to claim 1 or 2. The ratio (σ2 / σ1) of the intersection (σ1) between the stress (σ2) at break of the cured product and the tangent at the tensile deformation start point on the tensile stress-strain curve and the stress at the strain at break is 0.5. or more, and a tensile modulus of the cured product is 2500~40000kg / cm ^2, claim 1, 2 or 3 optical article for ionizing radiation curable resin composition. An optical article comprising a cured product of the ionizing radiation curable resin composition for an optical article according to any one of claims 1 to 4. A cured product layer (A) of an ionizing radiation curable resin composition comprising the ionizing radiation curable resin composition for an optical article according to any one of claims 1 to 4, and a sheet-like transparent resin layer (C) An optical article comprising: A cured product layer (A) of an ionizing radiation curable resin composition comprising the ionizing radiation curable resin composition for an optical article according to any one of claims 1 to 4, an adhesive layer (B), and a sheet Optical article comprising a transparent resin layer (C) in the form of a tube. A light guide made of a translucent flat plate, a light source unit provided adjacent to one or more of the side end faces of the light guide, a light reflecting layer provided on the back of the light guide, The surface light source comprised from the optical article as described in any one of Claims 5-7 laminated | stacked on the light emission surface of the light guide surface.

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