JP3885453B2 - Composition for anisotropic light scattering film and anisotropic light scattering film - Google Patents

Description

（Ｒは、水素原子或いは臭素原子を示す。ｎは自然数を示す。）
【００３１】
重合可能なエチレン性二重結合を分子内に１個以上有する化合物（Ｂ）とは、化学放射線によりラジカルを発生する開始剤の存在下、化学放射線照射により高分子化または架橋反応するラジカル重合性を有する化合物で、例えば、構造単位中にエチレン性の不飽和結合を少なくとも１個以上含むものであり、１官能であるビニルモノマーの他に多官能ビニルモノマーを含むものであり、またこれらの混合物であってもよい。さらに、該化合物は、上記エポキシ樹脂よりも屈折率が低い必要がある。
【００３２】
具体的には、（メタ）アクリル酸、イタコン酸、マレイン酸、（メタ）アクリルアミド、ジアセトンアクリルアミド、２−ヒドロキシエチル（メタ）アクリレート等の高沸点ビニルモノマー、さらには、脂肪族ポリヒドロキシ化合物、例えば、エチレングルコール、ジエチレングルコール、トリエチレングリコール、テトラエチレングリコール、プロピレングリコール、ネオペンチルグリコール、１，３−プロパンジオール、１，４−ブタンジオール、１，５−ペンタンジオール、１，６−ヘキサンジオール、１，１０−デカンジオール、トリメチロールプロパン、ペンタエリスリトール、ジペンタエリスリトール、ソルビトール、マンニトールなどのモノ、ジあるいはポリ（メタ）アクリル酸エステル類等が挙げられる。
【００３３】
本発明の組成物において用いられる（Ｃ）化学放射線によってラジカル種を発生する光開始剤系としては、２，２−ジメトキシ−１，２−ジフェニルエタン−１−オン等のベンジルメチルケタール類、１−ヒドロキシシクロヘキシルフェニルケトン、２−ヒドロキシ−２−メチル−１−フェニルプロパン−１−オン等のα−ヒドロキシケトン類、２−メチル−１［４−（メチルチオ）フェニル］−２−モルフォリノプロパン−１−オン、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）ブタノン−１等のα−アミノケトン類、ビス（２，６−ジメトキシベンゾイル）−２，４，４−トリメチルペンチルフォスフィンオキサイド等のビスアシルフォスフィンオキサイド類、２，２‘−ビス（ｏ−クロロフェニル）−４，４‘，５，５‘−テトラフェニル−１，１‘−ビイミダゾール、ビス（２，４，５−トリフェニル）イミダゾール等のビスイミダゾール類、Ｎ−フェニルグリシン等のＮ−アリールグリシン類、４，４‘−ジアジドカルコン等の有機アジド類、３，３‘，４，４‘−テトラ（ｔｅｒｔ−ブチルペルオキシカルボキシル）ベンゾフェノン等の有機過酸化物類をはじめ、Ｊ．Ｐｈｏｔｏｃｈｅｍ．Ｓｃｉ．Ｔｅｃｈｎｏｌ．，２，２８３（１９８７）．に記載される化合物、具体的には鉄アレーン錯体、トリハロゲノメチル置換ｓ−トリアジン、スルフォニウム塩、ジアゾニウム塩、フォスフォニウム塩、セレノニウム塩、アルソニウム塩、ヨードニウム塩等が挙げられる。また、ヨードニウム塩としては、Ｍａｃｒｏｍｏｌｅｃｕｌｅｓ、１０、１３０７（１９７７）．に記載の化合物、例えば、ジフェニルヨードニウム、ジトリルヨードニウム、フェニル（ｐ−アニシル）ヨードニウム、ビス（ｍ−ニトロフェニル）ヨードニウム、ビス（p −ｔｅｒｔ−ブチルフェニル）ヨードニウム、ビス（p −クロロフェニル）ヨードニウムなどのヨードニウムのクロリド、ブロミド、あるいはホウフッ化塩、ヘキサフルオロフォスフェート塩、ヘキサフルオロアルセネート塩、芳香族スルホン酸塩等や、ジフェニルフェナシルスルホニウム（ｎ−ブチル）トリフェニルボレート等のスルホニウム有機ホウ素錯体類を挙げることが出来る。
【００３４】
また、本発明の組成物は、保存時の重合を防止する目的で熱重合禁止剤を添加することが出来る。本発明の樹脂組成物に添加可能な熱重合禁止剤の具体例としては、ｐ−メトキシフェノール、ハイドロキノン、アルキル置換ハイドロキノン、カテコール、ｔｅｒｔ−ブチルカテコール、フェノチアジン等を挙げることができ、これらの熱重合禁止剤は、（Ｂ）重合可能なエチレン性二重結合を分子内に１個以上有する化合物１００重量部に対して０．００１から５重量部の範囲で添加されるのが望ましい。
【００３５】
さらに、本発明のエポキシ硬化剤（Ｄ）としては、大成社刊、「架橋剤ハンドブック」、ｐ．６０６〜ｐ．６５５記載の、脂肪族ポリアミン、芳香族アミン、ポリアミドアミン等のアミン類、三フッ化ホウ素錯化合物、ケチミン、イミダゾール、酸無水物等が挙げられるが、この限りではない。
【００３６】
本発明の組成物は、エポキシ樹脂の硬化を促進する目的で第三アミン等の重合触媒（硬化促進剤）を加えてもよい。なお、配合量は一定せず、それぞれの硬化剤により決定されなけらばならない。
【００３７】
本発明の組成物において用いられる分子内に少なくともひとつのグリシジル基を有した芳香族化合物（Ｅ）は、重合可能なエチレン性二重結合を分子内に１個以上有する化合物よりは反応性が低く、屈折率は高い必要があり、また、露光後の加熱時に液体であるようなものが望ましい。該化合物は、重合可能なエチレン性二重結合を分子内に１個以上有する化合物が重合する際には液体として存在するため、重合可能なエチレン性二重結合を分子内に１個以上有する化合物の拡散移動を起き易くする、いわゆる可塑剤的な役割を果たし、樹脂が硬化するときに硬化するため、異方性散乱フィルム中では重合物として存在するため、熱劣化等の悪影響を及ぼすことはなく、さらに、屈折率も重合可能なエチレン性二重結合を分子内に１個以上有する化合物よりも高いため散乱性に悪影響を及ぼすことはない。
【００３８】
具体的には、グリシジルフェニルエーテル、p-ブロモフェニルグリシジルエーテル、グリシジル−１−ナフチルエーテル、グリシジル−２−ナフチルエーテル、グリシジルインダリルエーテル、ベンゾチアゾリルグリシジルエーテル等が挙げられるがこの限りではない。
【００３９】
さらに、記録する化学放射線の波長に応じて、本発明の化学放射線によってラジカル種を発生する光重合開始剤（Ｃ）を増感せしめる増感色素（Ｆ）を加えても良い。光重合開始剤（Ｃ）を増感せしめる増感色素（Ｆ）としては、シアニンまたはメロシアニン誘導体、クマリン誘導体、カルコン誘導体、キサンテン誘導体、チオキサンテン誘導体、アズレニウム誘導体、スクアリリウム誘導体、ポルフィリン誘導体などの有機染料化合物が使用でき、その他に「色素ハンドブック」（大河原信他編 講談社刊１９８６年）、「機能性色素の化学」（大河原信他編、シーエムシー刊 １９８１年）、「特殊機能材料」（池森忠三郎他編 シーエムシー刊 １９８６年）に記載されている色素及び増感剤が用いられる。なお、これらに限定されるものではなく、その他の可視域の光に対して吸収を示す色素及び増感剤であり、使用する光重合開始剤を分光増感出来れば用いることが出来る。これらは必要に応じて任意の比率で二種以上で用いてもかまわない。
【００４０】
本発明の組成物に含有される成分（Ｂ）の量は、（Ａ）１００重量部に対して２０から２００重量部の範囲をとることが可能であり、好ましくは３０から１００重量部である。成分（Ｃ）の光重合開始剤の量は、成分（Ａ）１００重量部に対し、０．１から２０重量部、好ましくは１から１０重量部である。さらに、成分（Ｄ）のエポキシ硬化剤は、成分（Ａ）１００重量部に対して０．１から１０重量部、好ましくは０．５から５までの範囲をとることが可能である。成分（Ｅ）のグリシジル基を有した芳香族化合物を使用する場合の量は、成分（Ａ）１００重量部に対し、２０から１００重量部、好ましくは２０から６０重量部である。成分（Ｆ）を使用する場合の量は、（Ａ）１００重量部に対して０．１から５重量部の範囲をとることが可能であり、好ましくは０．２から０．５重量部である。使用量は、感光層膜厚と該膜厚の光学濃度によって制限を受ける。すなわち、光学濃度が２を越えない範囲で使用することが好ましい。
【００４１】
この様にこれらの各成分を適宜選択し、任意の割合で混合して得た感光液をバーコーター、アプリケーター、ドクターブレード、ロールコーター、ダイコーター、コンマーコーター等の公知の塗工手段を用いてガラス板やフィルム等の基材に塗布する。
【００４２】
なお、感光液を塗布する際は、必要に応じて適当な溶剤で希釈してもよいが、その場合には基材上に塗布した後に、乾燥を要する。上記溶剤としては、ジクロルメタン、クロロホルム、アセトン、２−ブタノン、シクロヘキサノン、エチルアセテート、２−メトキシエタノール、２−エトキシエタノール、２−ブトキシエタノール、２−エトキシエチルアセテート、２−ブトキシエチルアセテート、２−メトキシエチルエーテル、２−エトキシエチルエーテル、２−（２−エトキシエトキシ）エタノール、２−（２−ブトキシエトキシ）エタノール、２−（２−エトキシエトキシ）エチルアセテート、２−（２−ブトキシエトキシ）エチルアセテート、テトラヒドロフラン、１，４−ジオキサン等が挙げられる。
【００４３】
さらに、記録可能な屈折率差は作製方法や記録材料などにより制限を受けるため、大きな屈折率差を持つ場合はフィルム膜厚を薄く、小さな屈折率差を持つ場合はフィルム膜厚を厚くすることで、本発明の組成物を用いて光散乱フィルムを実現することが可能である。
【００４４】
屈折率の異なる部分の大きさは、光散乱を生じるためにランダムで規則性はないが、必要な散乱性を持つために、その平均の大きさは直径で０．１μｍから３００μｍの範囲内でそれぞれの用途に必要な散乱性に応じて適宜選択する。
【００４５】
また、前記屈折率の異なる部分のフィルム表面上での分布は、光散乱を生じるためにランダムで規則性はないが、必要な散乱性を持たせるために、フィルム全体の平均屈折率をｎとすると、その確立分布はｎを中心とする正規分布を呈する。或いは、屈折率ｎの最小値ｎmin で最大値をとり指数関数的に屈折率の最大値ｎmax まで単調減少するような確立分布、或いは単調増加する確立分布に従って分布していてもよい。
【００４６】
以下、本発明の光散乱フィルムを作製する手段について述べる。本発明の光散乱フィルムは光学的な露光手段により作製することができる。図５はランダムマスクパターンを利用して作製する光学系の一例を示す説明図である。ＵＶ光源６から出た紫外光はコリメート光学系７により平行光８とし、マスク原版９を照射する。
【００４７】
マスク原版９のＵＶ照射側とは反対の面には感光材料５を密着して配置しており、マスク原版９のパターンを感光材料５に露光照射する。この際、図示のようにＵＶ平行光８とマスク原版９は所定角度αだけ傾いて配置されているため、パターン露光は感光材料５中で、所定角度傾いてなされることになる。この角度が、光散乱フィルム中の屈折率の異なる部分の傾斜角度（すなわち、入射角度依存性の散乱角度θ）に相当することになるので、前記角度は用途に応じて０から６０度程度の範囲内で適宜選択する。
【００４８】
また、ここで使用する感光材料５は、ＵＶ光の露光部と未露光部を屈折率の変化形態で記録できる感光材料であり、記録しようとする濃淡模様より高い解像力を持ち、その厚みの方向にもパターンを記録できるような材料である必要がある。
【００４９】
図５で用いている所定のランダムパターンを持つマスク原版９は、計算機を用いた乱数計算から作製した白黒パターンデータを、所謂フォトリソグラフィーの手法によりガラス基板１０上の金属クロムパターン１１としてエッチングしたものを用いてもよい。もちろんマスク原版の作成方法としては、上記方式に限定されるものではなく、リス乾板を使った写真手法などにより作製しても同様なマスクを作製できる事は周知である。
【００５０】
図６は、図２に示す構造の光散乱フィルムをスペックルパターンを利用して作製する光学系の一例を示す説明図である。レーザー光源１３から出たレーザー光１４ですりガラス１５を照射する。すりガラス１５のレーザー照射側とは反対の面には所定距離Ｆをおいて感光材料５を配置し、すりガラス１５で透過散乱したレーザー光が作り出す複雑な干渉パターンであるスペックルパターンを感光材料５に露光照射される。
【００５１】
この際、図示のようにすりガラス１０と感光材料５は所定角度αだけ傾いて配置されているため、スペックルパターンは感光材料中で、所定角度傾いて露光されることになる。この角度が、光散乱フィルム中の屈折率の異なる部分の傾き（すなわち、入射角度依存性の散乱ピーク角度θ）に相当することになるので、前記角度は用途に応じて０から６０度程度の範囲内で適宜選択する。
【００５２】
記録に使用するレーザ光源は、アルゴンイオンレーザーやクリプトンイオンレーザーの６４７．９ｎｍ、５１４．５ｎｍ、４８８ｎｍ、４５７．９ｎｍ、４１３ｎｍ、３６４ｎｍ或いは３５１ｎｍの波長のうち、感光材料の感度に応じて適宜選択して使用する事ができる。またアルゴンイオン、クリプトンイオンレーザー以外でもコヒーレント性の良いレーザー光源であれば仕様可能で、例えばヘリウムネオンレーザーや半導体レーザなどが使用できる。
【００５３】
スペックルパターンは、コヒーレント性が良い光が粗面で散乱反射または透過した時に生じる明暗の斑点模様であり、粗面の微小な凹凸で散乱した光が不規則な位相関係で干渉するために生じるものである。
【００５４】
「光測定ハンドブック朝倉書店刊田光幸敏治ほか著１９９４年１１月２５日発行」の記述（ｐ．２６６〜ｐ．２６８）によれば、濃度や位相が位置によってランダムな値を示すようなスペックルパターンでは、前記パターンの大きさは、感光材料から拡散板を見込む角度に反比例して、パターンの平均径が決定される。従って、拡散板の大きさを、水平方向よりも垂直方向で大きくした場合、感光材料上に記録されるパターンは、水平方向よりも垂直方向が細かいものとなる。
【００５５】
図６の光学系での作製方法によるスペックルパターンは、使用するレーザー光の波長λ及びすりガラスの大きさＤ、すりガラスと感光材料との距離Ｆが、記録されるスペックルパターンの平均サイズｄを決定し、一般に次式で表される。
ｄ＝１．２λＦ／Ｄ
また、このスペックルパターンの奥行き方向の平均の長さｔは
ｔ＝４．０λ（Ｆ／Ｄ）²
で表される。
【００５６】
以上よりλ及びＦ／Ｄの値を最適な散乱性を持つように最適化することで所望の３次元的な屈折率分布を持つ本発明の光散乱フィルムを得ることが出来る。
【００５７】
一例として、λ＝０．５μｍで、Ｆ／Ｄ＝２とすると、ｄ＝１．２μｍ、ｔ＝８μｍとなり、フィルム表面上の濃淡模様は平均１．２μｍで分布し、フィルム厚み方向には前記傾斜角度に従った方向に平均８μｍの大きさで分布することになる。
【００５８】
ただし、これらの大きさはあくまでも平均の大きさであり、実際にはこれらの大きさを中心に大小様々な大きさで屈折率の異なる部分が表面上及び奥行き方向に傾斜して分布することになり、図２に示すような本発明の光散乱フィルムとなる。
【００５９】
以下、本発明の実施の形態について具体的な実施例を挙げて説明する。
【００６０】
＜実施例１＞
ビスフェノール系エポキシ樹脂エピコート１００４（エポキシ当量：８７５−９７５、油化シェルエポキシ（株）製商品名）１００重量部、トリプロピレングリコールジアクリレート（ＶＩＳＣＯＡＴ−３１０ＨＰ、大阪有機化学（株）製商品名）５０重量部および１−ヒドロキシシクロヘキシルフェニルケトン（ＩＲＧＡＣＵＲＥ１８４、チバ・スペシャリティ・ケミカルズ社製商品名）３．０重量部、Ｎ−アミノエチルピペラジン（Ｎ−ＡＥＰ、広栄化学社製）１０．０重量部を２−ブタノン１６０重量部に混合溶解したものを感光液とした。該感光液を青板ガラス（１．１ｍｍ厚、５インチ角）にドクターブレードで塗布、乾燥し記録用媒体とした。
【００６１】
該記録用媒体を、図６に示した光学系で、光源としてアルゴンレーザ（３６４ｎｍ）をレンズを用いて広げた光ですりガラス１５を介して、記録材料面から露光した( α＝２２゜、２０ｍＪ／ｃｍ² ) 後、８０℃で１０分加熱後、ＵＶ光源で全面露光した（５００ｍＪ／ｃｍ² ）。さらに１５０℃で６０分加熱し、硬化物をガラス基板から剥離することによって光散乱性フィルムを得た。得られた該フィルムの厚みは５５ミクロンであった。
【００６２】
評価は、島津製作所（株）製の分光光度計で各角度で透過率（波長範囲；４００〜６００ｎｍ）を測定した。結果（全波長平均透過率）を表１に示す。
【００６３】
【表１】

【００６４】
＜実施例２＞
ビスフェノール系エポキシ樹脂エピコート１００４の代わりに、ビスフェノールＡ型エポキシ樹脂ＥＰ１００７（エポキシ当量：１７５０−２２００、油化シェルエポキシ（株）製商品名）１００重量部とグリシジルフェニルエーテル３０重量部を使う以外は実施例１と同様にして操作し、作製した光散乱性フィルムを得た。得られた該フィルムの厚みは３１ミクロンであった。結果を表２に示す。
【００６５】
【表２】

【００６６】
＜実施例３＞
グリシジルフェニルエーテルの代わりにジブロモトリルグリシジルエーテル（ＢＲＯＣ、日本化薬（株）製商品名）を使う以外は実施例２と同様にして操作し、作製した光散乱性フィルムを得た。得られた該フィルムの厚みは３２ミクロンであった。結果を表３に示す。
【００６７】
【表３】

【００６８】
＜実施例４＞
Ｎ−アミノエチルピペラジンの代わりに、メチルエンドメチレンテトラヒドロ無水フタル酸（カヤハードＭＣＤ、日本化薬（株）商品名）１０重量部に変える以外は実施例２と同様にして操作し、作製した光散乱性フィルムを得た。得られた該フィルムの厚みは３１ミクロンであった。結果を表４に示す。
【００６９】
【表４】

【００７０】
＜実施例５＞
トリプロピレングリコールジアクリレート（ＶＩＳＣＯＡＴ−３１０ＨＰ、大阪有機化学製（株）商品名）の代わりにネオペンチルグリコールジアクリレート（ＶＩＳＣＯＡＴ−２１５、大阪有機化学製（株）商品名）を使う以外は実施例２と同様にして操作し、作製した光散乱性フィルムを得た。得られた該フィルムの厚みは２９ミクロンであった。結果を表５に示す。
【００７１】
【表５】

【００７２】
＜実施例６＞
１−ヒドロキシシクロヘキシルフェニルケトン（ＩＲＧＡＣＵＲＥ１８４、チバ・スペシャリティ・ケミカルズ社製商品名）３．０重量部の代わりに２−ヒドロキシ−２−メチル−１−フェニルプロパン−２−オン（ＤＡＲＯＣＵＲＥ１１７３、チバ・スペシャリティ・ケミカルズ社製商品名）３．０重量部を使う以外は実施例１と同様にして操作し、作製した光散乱性フィルムを得た。得られた該フィルムの厚みは３２ミクロンであった。結果を表６に示す。
【００７３】
【表６】

【００７４】
＜実施例７＞
ビスフェノールＡ型エポキシ樹脂ＥＰ１００７（油化シェルエポキシ（株）製商品名）１００重量部の代りに、ビスフェノールＡ型エポキシ樹脂ＥＰ１００７（油化シェルエポキシ（株）製商品名）６０重量部と臭素化ビスフェノールＡ型エポキシ樹脂ＹＬ６１６７（油化シェルエポキシ（株）製商品名）４０重量部の混合系にした以外は実施例２と同様にして操作し、作製した光散乱性フィルムを得た。得られた該フィルムの厚みは２９ミクロンであった。結果を表７に示す。
【００７５】
【表７】

【００７６】
＜実施例８＞
１−ヒドロキシシクロヘキシルフェニルケトン（ＩＲＧＡＣＵＲＥ１８４、チバ・スペシャリティ・ケミカルズ社製商品名）３．０重量部の代わりに、４，４‘−ビス（ｔｅｒｔ−ブチルフェニル）ヨードニウムヘキサフルオロフォスフェート４．０重量部および１−（ｐ−メトキシフェニル）−３−（ｐ−ジメチルアミノフェニル）−２−プロペン−１−オン０．２５重量部を使い、光源をクリプトンレーザ（４１３ｎｍ）を使用する以外は実施例１と同様にして操作し、光散乱性フィルムを作製したが散乱性は光散乱性フィルムを得た。得られた該フィルムの厚みは７０ミクロンであった。結果を表８に示す。
【００７７】
【表８】

【００７８】
【発明の効果】
本組成物を用いれば、所定角度で入射する光に対しては光散乱が生じ、逆にそれとは垂直な光に対しては透明フィルムとして機能することにより、光散乱性に入射角度選択性を持ち、そのため、散乱性を要する光と散乱性が不要な光とを、そのフィルムへの入射角度により分離することができ、結果として表示装置などに用いた場合に、不必要な散乱を生じることなく表示の明るさや細かさ、コントラストを向上し、且つ表示像のぼけを軽減させる等の効果がある光散乱フィルムを作製することができる。
【００７９】
また、光散乱が生じる入射角度で光が入射した際に、その散乱光の広がりが、縦横で異なるような散乱異方性をも併せ持つフィルムの作製が可能である。そのため、必要な方向にのみ散乱光を出射することが出来、結果として表示装置などに用いた場合に、不必要な散乱を生じることなく表示の明るさ、コントラストを向上させる等の効果がある。
【００８０】
【図面の簡単な説明】
【図１】本発明の光散乱フィルムを示す説明図であり、左が平面図、右が断面図である。
【図２】本発明の光散乱フィルムを示す説明図であり、左が平面図、右が断面図説明である。
【図３】本発明の光散乱フィルムの持つ入射角度依存性の一例を示すグラフ図である。
【図４】本発明の光散乱フィルムが持つ光散乱の異方性を説明する説明図である。
【図５】図１に示す構造の光散乱フィルムを、マスクパターンを利用して作製する光学系の一例を示す説明図である。
【図６】図２に示す構造の光散乱フィルムを、スペックルパターンを利用して作製する光学系の一例を示す説明図である。
【符号の説明】
１…光散乱フィルム
２…散乱方向から入射する照明光
３…透過方向から入射する照明光
４…実測したヘイズ値のプロット
５…感光材料
６…ＵＶ光源
７…コリーメート光学系
８…平行光
９…マスク原版
１０…ガラス基板
１１…クロムパターン
１２…光ファイバー
１３…レーザー光源
１４…レーザー光
１５…すりガラス
１６…ビームエキスパンダー
１７…コリメーター[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a composition for a light diffusing film that has different scattering properties (or has incident angle selectivity) according to the incident angle of light and has anisotropy in light scattering properties.
[0002]
[Prior art]
In a display device using light such as a reflective liquid crystal display device or a transmissive liquid crystal display device, a viewing angle at the time of observation is ensured (that is, the display image is brightly displayed on the front surface of the display device), In order to make the display screen visible with uniform brightness over the entire surface of the display screen, a light diffusion film is disposed on the front surface of the apparatus. As a conventional light scattering film, a resin film whose surface is processed into a mat shape, a resin film including a diffusing material inside, or the like is used.
[0003]
In the case of a conventional resin film processed into a mat shape or a film containing a diffusing material inside, it is difficult in principle to have a function such as a change in scattering depending on the incident angle of incident light. There is no such function.
[0004]
In the case of a light-scattering film whose surface has been processed into a mat shape, the mat surface is physically formed on the film surface like a sand blaster treatment, or the mat surface is chemically formed by dissolution treatment with an acidic or alkaline solution. . Accordingly, it is difficult to control the light scattering property, and it is impossible to change the vertical and horizontal scattering properties, so that it is impossible to provide scattering anisotropy.
[0005]
In addition, even in a light scattering film including a diffusing material inside, attempts have been made to control the refractive index, size, shape, etc. of the diffusing material in order to control the scattering property, but this is technically difficult. However, it cannot be said that it is practically sufficient.
[0006]
Therefore, in the above light scattering film, there is no scattering incident angle dependency and there is little or no light scattering anisotropy, so unnecessary scattered light is generated when used in a display device, and as a result. There is a problem in that the brightness and contrast of the display are reduced or the display image is blurred.
[0007]
On the other hand, JP-A-8-20180 is known as a proposal relating to a reflective liquid crystal display device using a scattering plate having anisotropy in light scattering. The scattering plate disclosed in the above publication is a scattering plate having almost no back scattering characteristics and strong forward scattering characteristics, and selectively scatters either incident light to the liquid crystal display device or display light emitted from the liquid crystal display device. It has the characteristic to make it.
[0008]
  The anisotropic light-scattering film composition according to claim 2 is (E).At normal temperature, the refractive index isAn aromatic compound having a higher refractive index than that of the compound (B) having radical polymerizability and having at least one glycidyl group in the molecule is added.
[0009]
Japanese Patent Laid-Open No. 9-152602 is known as a proposal relating to a transmission type liquid crystal display device using a hologram as a scattering plate. The above proposal scatters display light emitted from a liquid crystal display device having a backlight, and employs a hologram as a scattering plate. Therefore, it is easy to make the scattering characteristics anisotropic, Although it is also possible to control the lateral scattering characteristics, it will inevitably involve spectroscopy (wavelength dispersion), so the color of the display light will change as the viewing point changes. Will be.
[0010]
[Problems to be solved by the invention]
The present invention gives the scattering characteristics anisotropy (forward or backward, and dependency on the incident angle), makes it easy to control the scattering characteristics related to the vertical and horizontal scattering ranges, and displays them depending on the observation position. An object of the present invention is to provide a composition for obtaining an anisotropic scatterer in which the color of light does not change.
[0011]
[Means for Solving the Problems]
In the anisotropic scattering film of the present invention, portions having different refractive indexes are distributed in irregular shapes and thicknesses inside the film, thereby forming a light and shade pattern consisting of high and low refractive indexes, and different refractive indexes. By optimizing the size, shape, and distribution of parts along the longitudinal and lateral directions on the film surface and the thickness direction of the film, the scattering characteristics depending on the incident angle can be changed, and in the unnecessary direction. The present invention is characterized in that there is a difference in refractive index between the cationically polymerizable compound and the radically polymerizable compound, and the light is scattered only in a necessary direction (range). An anisotropic scattering film composition is provided.
[0012]
The composition for anisotropic light scattering film according to claim 1 comprises at least (A) bisphenol A type epoxy resin or brominated bisphenol A type epoxy resin, (B) a compound having radical polymerizability, and (C) chemistry. A photopolymerization initiator that generates radical species by radiation and (D) an epoxy curing agent, and (B) the refractive index of the compound having radical polymerizability is (A) bisphenol A type epoxy resin or brominated bisphenol A type epoxy. It is lower than an aromatic compound having at least one glycidyl group in the resin and (C) molecule.
[0013]
The composition for anisotropic light-scattering film according to claim 2, wherein an aromatic compound having at least one glycidyl group in the molecule is added, which is higher than the refractive index of the compound (B) having (E) radical polymerizability. It is characterized by doing.
[0014]
The anisotropic light-scattering film composition according to claim 3 is characterized in that the bisphenol A type epoxy resin or brominated bisphenol A type epoxy resin (A) has an epoxy equivalent of 400 to 2200.
[0015]
The composition for anisotropic light-scattering film according to claim 4, wherein the radically polymerizable compound (B) is an ethylenically unsaturated compound having a liquid at normal temperature and pressure and a boiling point of 100 ° C or higher at normal pressure. It is a compound having at least one bond.
[0016]
The composition for anisotropic light scattering film according to claim 5, wherein the compound (B) having radical polymerizability is added to 100 parts by weight of the bisphenol A type epoxy resin or brominated bisphenol A type epoxy resin (A). It is characterized by mixing 20 to 80 parts by weight.
[0017]
The anisotropic light-scattering film composition according to claim 6 is characterized in that a sensitizing dye (F) that sensitizes the photoinitiator (D) that generates radical species by the chemical radiation is added.
[0018]
The anisotropic light-scattering film of Claim 7 was created using the composition for anisotropic light-scattering films of Claims 1-6, and the part where refractive index differs in an irregular shape and thickness inside a film. The light having a structure in which a light and shade pattern having a high and low refractive index is formed, and portions having different refractive indexes are distributed in a layered manner inclined with respect to the thickness direction of the film. It is a scattering film, light scattering occurs for light incident at an angle along the tilt direction, and it acts as a mere transparent film for light perpendicular to the tilt direction. It is an anisotropic light-scattering film having angle selectivity.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings.
FIG. 1 shows a light scattering film 1 in which portions having different refractive indexes are distributed in an irregular shape and thickness, and a light and shade pattern having a high and low refractive index (expressed in white and black in the figure) is formed. Are left side plan views and right side sectional views.
[0020]
As can be seen from the plan view, the shape of the portion having a different refractive index is horizontally long. Further, as can be seen from the cross-sectional view, the portions having different refractive indexes have a structure distributed in a layer shape inclined with respect to the thickness direction of the film. In FIG. 1, the refractive index distribution is uniform (the color does not change in the inclined direction) in the direction in which the portions having different refractive indexes are inclined in layers.
[0021]
Drawing 2 is an explanatory view showing light scattering film 1 concerning another embodiment, and the left is a top view and the right is a sectional view. In FIG. 2, the shape of the part with different refractive index is vertically long, and the refractive index distribution is irregular in the direction in which the part with different refractive index is inclined in layers (the color changes even in the inclined direction). Is).
[0022]
First, the optical characteristics of the light scattering film of FIGS. Light scattering occurs with respect to light incident at an angle along the tilt direction in which portions having different refractive indexes are distributed in layers (in the direction of arrow 2 in FIG. 2, which forms an angle θ from the normal of the film). Become.
[0023]
For light incident at an angle perpendicular to the tilt direction (the direction of arrow 3 in the figure), it functions as a simple transparent film, and the incident light is emitted without being scattered.
[0024]
Next, considering the plan view, if the shape of the part with different refractive index is vertically long (or horizontally long) and light incident on that part is scattered and emitted, the light scattering characteristics of the emitted light from each part Has anisotropy that is horizontally long (or vertically long). In FIG. 1, since the shape is horizontally long, the emitted light is scattered vertically. In FIG. 2, since the shape is vertically long, the emitted light is scattered horizontally.
[0025]
FIG. 3 is a graph showing an example of the incident angle dependency of the light scattering film 1 produced using the composition of the present invention. As indicated by the solid line in the figure, the haze value is 80% or more for light in a specific incident angle range (0 to 60 degrees in the figure), and conversely, the incident angle (-60 degrees in the figure) is symmetric. The haze value with respect to light of 0 degree to 20 degrees or less is 20% or less, which indicates the incident angle dependency of the scattering property referred to in this specification.
[0026]
In addition, as described above, when the shape of the part having different refractive index is vertically long (or horizontally long), when light incident on the part is scattered and emitted, the light scattering characteristics of the light emitted from each part are , Has anisotropy that is horizontally long (or vertically long). For example, if the shape is horizontally long as shown in FIG. 1, the scattered outgoing light from the light scattering film has a distribution that becomes a vertically long ellipse as shown in FIG.
[0027]
Next, the composition for anisotropic light scattering film of the present invention will be described in detail. As described above, the inside of the anisotropic light-scattering film produced with the composition of the present invention has a light and shade pattern with a high and low refractive index formed by irregularly distributed portions having different refractive indexes. Has been.
[0028]
If the difference in refractive index is too small, the scattering property is deteriorated. On the other hand, if the difference is too large, light scattering occurs regardless of the angle at which light is incident. It becomes difficult to have.
[0029]
The bisphenol A type epoxy resin or brominated bisphenol A type epoxy resin used in the composition of the present invention is a resin represented by the general formula (I), and its epoxy equivalent is preferably in the range of 400-2200. When the resin is heated in the presence of a curing agent, crosslinking occurs and cures.
[0030]
[Chemical 1]

(R represents a hydrogen atom or a bromine atom. N represents a natural number.)
[0031]
The compound (B) having at least one polymerizable ethylenic double bond in the molecule is a radical polymerizability that undergoes polymerisation or crosslinking reaction by actinic radiation in the presence of an initiator that generates radicals by actinic radiation. A compound having at least one ethylenically unsaturated bond in a structural unit, a polyfunctional vinyl monomer in addition to a monofunctional vinyl monomer, and a mixture thereof It may be. Further, the compound needs to have a refractive index lower than that of the epoxy resin.
[0032]
  Specifically, high-boiling vinyl monomers such as (meth) acrylic acid, itaconic acid, maleic acid, (meth) acrylamide, diacetone acrylamide, 2-hydroxyethyl (meth) acrylate, and aliphatic polyhydroxy compounds, For example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, neopentyl glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6- Mono-, di- or poly (meth) acrylates such as hexanediol, 1,10-decanediol, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, mannitol, etc.Is mentioned.
[0033]
Examples of the photoinitiator system that generates radical species by actinic radiation (C) used in the composition of the present invention include benzylmethyl ketals such as 2,2-dimethoxy-1,2-diphenylethane-1-one, 1 -Hydroxycyclohexyl phenyl ketone, α-hydroxy ketones such as 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropane- Α-aminoketones such as 1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentyl Bisacylphosphine oxides such as phosphine oxide, 2,2′-bis (o-chlorophenyl) -4,4 ', 5,5'-tetraphenyl-1,1'-biimidazole, bisimidazoles such as bis (2,4,5-triphenyl) imidazole, N-arylglycines such as N-phenylglycine, Organic peroxides such as organic azides such as 4′-diazidochalcone, 3,3 ′, 4,4′-tetra (tert-butylperoxycarboxyl) benzophenone, and the like; Photochem. Sci. Technol. , 2, 283 (1987). And specifically, iron arene complexes, trihalogenomethyl-substituted s-triazines, sulfonium salts, diazonium salts, phosphonium salts, selenonium salts, arsonium salts, iodonium salts, and the like. Moreover, as an iodonium salt, Macromolecules, 10, 1307 (1977). Compounds such as diphenyliodonium, ditolyliodonium, phenyl (p-anisyl) iodonium, bis (m-nitrophenyl) iodonium, bis (p-tert-butylphenyl) iodonium, bis (p-chlorophenyl) iodonium, etc. Iodonium chloride, bromide, or sulfonium organoboron complexes such as borofluoride, hexafluorophosphate salt, hexafluoroarsenate salt, aromatic sulfonate, and diphenylphenacylsulfonium (n-butyl) triphenylborate You can list things.
[0034]
In addition, a thermal polymerization inhibitor can be added to the composition of the present invention for the purpose of preventing polymerization during storage. Specific examples of the thermal polymerization inhibitor that can be added to the resin composition of the present invention include p-methoxyphenol, hydroquinone, alkyl-substituted hydroquinone, catechol, tert-butylcatechol, phenothiazine, and the like. The inhibitor is preferably added in an amount of 0.001 to 5 parts by weight per 100 parts by weight of the compound (B) having at least one polymerizable ethylenic double bond in the molecule.
[0035]
  Further, the epoxy of the present inventionHardener(D) includes Taiseisha, “Crosslinking agent handbook”, p. 606-p. Examples thereof include, but are not limited to, amines such as aliphatic polyamines, aromatic amines, and polyamidoamines described in 655, boron trifluoride complex compounds, ketimines, imidazoles, and acid anhydrides.
[0036]
The composition of the present invention may contain a polymerization catalyst (curing accelerator) such as a tertiary amine for the purpose of accelerating the curing of the epoxy resin. The blending amount is not constant and must be determined by each curing agent.
[0037]
The aromatic compound (E) having at least one glycidyl group in the molecule used in the composition of the present invention is less reactive than a compound having at least one polymerizable ethylenic double bond in the molecule. The refractive index needs to be high, and is preferably a liquid when heated after exposure. The compound is present as a liquid when a compound having at least one polymerizable ethylenic double bond in the molecule is polymerized, so that the compound has at least one polymerizable ethylenic double bond in the molecule. It plays a role of so-called plasticizer that makes it easy to cause diffusion movement of the resin, and since it cures when the resin cures, it exists as a polymer in the anisotropic scattering film, so it has adverse effects such as thermal deterioration Furthermore, since the refractive index is higher than that of a compound having at least one polymerizable ethylenic double bond in the molecule, the scattering property is not adversely affected.
[0038]
Specific examples include, but are not limited to, glycidyl phenyl ether, p-bromophenyl glycidyl ether, glycidyl-1-naphthyl ether, glycidyl-2-naphthyl ether, glycidyl indaryl ether, benzothiazolyl glycidyl ether, and the like. .
[0039]
Furthermore, a sensitizing dye (F) for sensitizing the photopolymerization initiator (C) that generates radical species by the chemical radiation of the present invention may be added according to the wavelength of the chemical radiation to be recorded. Sensitizing dyes (F) for sensitizing the photopolymerization initiator (C) include organic dyes such as cyanine or merocyanine derivatives, coumarin derivatives, chalcone derivatives, xanthene derivatives, thioxanthene derivatives, azurenium derivatives, squarylium derivatives, porphyrin derivatives, etc. In addition, "Dye Handbook" (Shin Okawara et al., Edited by Kodansha 1986), "Chemicals of Functional Dye" (Shin Okawara et al., CM 1981), "Special Functional Materials" (Tadachi Ikemori) The dyes and sensitizers described in Saburo et al., Edited by CMC (1986) are used. In addition, it is not limited to these, It is the pigment | dye and sensitizer which show absorption with respect to the light of other visible region, and if the photoinitiator to be used can be spectrally sensitized, it can be used. Two or more of these may be used in any ratio as required.
[0040]
The amount of component (B) contained in the composition of the present invention can be in the range of 20 to 200 parts by weight, preferably 30 to 100 parts by weight, with respect to 100 parts by weight of (A). . The amount of the photopolymerization initiator of component (C) is 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, relative to 100 parts by weight of component (A). Furthermore, the epoxy curing agent of component (D) can range from 0.1 to 10 parts by weight, preferably from 0.5 to 5 parts per 100 parts by weight of component (A). The amount of the aromatic compound having a glycidyl group as the component (E) is 20 to 100 parts by weight, preferably 20 to 60 parts by weight with respect to 100 parts by weight of the component (A). The amount when component (F) is used can range from 0.1 to 5 parts by weight, preferably 0.2 to 0.5 parts by weight, per 100 parts by weight of (A). is there. The amount used is limited by the film thickness of the photosensitive layer and the optical density of the film thickness. That is, it is preferable to use the optical density within a range not exceeding 2.
[0041]
Thus, each of these components is appropriately selected, and the photosensitive solution obtained by mixing at an arbitrary ratio is used by using a known coating means such as a bar coater, an applicator, a doctor blade, a roll coater, a die coater, and a comma coater. It is applied to a substrate such as a glass plate or film.
[0042]
In addition, when apply | coating a photosensitive solution, you may dilute with a suitable solvent as needed, but in that case, after apply | coating on a base material, drying is required. Examples of the solvent include dichloromethane, chloroform, acetone, 2-butanone, cyclohexanone, ethyl acetate, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-ethoxyethyl acetate, 2-butoxyethyl acetate, 2-methoxy. Ethyl ether, 2-ethoxyethyl ether, 2- (2-ethoxyethoxy) ethanol, 2- (2-butoxyethoxy) ethanol, 2- (2-ethoxyethoxy) ethyl acetate, 2- (2-butoxyethoxy) ethyl acetate , Tetrahydrofuran, 1,4-dioxane and the like.
[0043]
Furthermore, since the recordable refractive index difference is limited by the manufacturing method and recording material, the film thickness is reduced when there is a large refractive index difference, and the film thickness is increased when there is a small refractive index difference. Thus, a light scattering film can be realized using the composition of the present invention.
[0044]
The sizes of the portions having different refractive indexes are random and non-regular in order to cause light scattering, but in order to have the necessary scattering properties, the average size is within a range of 0.1 μm to 300 μm in diameter. It selects suitably according to the scattering property required for each use.
[0045]
In addition, the distribution of the portions having different refractive indexes on the film surface is random and non-regular in order to cause light scattering, but in order to have necessary scattering properties, the average refractive index of the entire film is set to n. Then, the probability distribution exhibits a normal distribution centering on n. Alternatively, it may be distributed according to a probability distribution that takes a maximum value at the minimum value nmin of the refractive index n and monotonously decreases exponentially to the maximum value nmax of the refractive index, or a monotonically increasing probability distribution.
[0046]
Hereinafter, means for producing the light scattering film of the present invention will be described. The light scattering film of the present invention can be produced by optical exposure means. FIG. 5 is an explanatory diagram showing an example of an optical system manufactured using a random mask pattern. The ultraviolet light emitted from the UV light source 6 is converted into parallel light 8 by the collimating optical system 7 and irradiated on the mask original plate 9.
[0047]
The photosensitive material 5 is disposed in close contact with the surface of the mask original 9 opposite to the UV irradiation side, and the pattern of the mask original 9 is exposed to the photosensitive material 5 by exposure. At this time, the UV parallel light 8 and the mask original plate 9 are inclined at a predetermined angle α as shown in the figure, so that pattern exposure is performed at a predetermined angle in the photosensitive material 5. Since this angle corresponds to the inclination angle of the portion having a different refractive index in the light scattering film (that is, the incident angle-dependent scattering angle θ), the angle is about 0 to 60 degrees depending on the application. Select appropriately within the range.
[0048]
The photosensitive material 5 used here is a photosensitive material that can record the exposed portion and the unexposed portion of UV light in a form of change in refractive index, and has a higher resolving power than the shading pattern to be recorded, and its thickness direction. In addition, the material must be capable of recording a pattern.
[0049]
The mask original plate 9 having a predetermined random pattern used in FIG. 5 is obtained by etching the black and white pattern data produced from the random number calculation using a computer as the metal chromium pattern 11 on the glass substrate 10 by a so-called photolithography technique. May be used. Of course, the method for preparing the mask original plate is not limited to the above-described method, and it is well known that a similar mask can be manufactured even if it is manufactured by a photographic technique using a squirrel plate.
[0050]
FIG. 6 is an explanatory view showing an example of an optical system for producing a light scattering film having the structure shown in FIG. 2 using a speckle pattern. A glass 15 is irradiated with a laser beam 14 emitted from a laser light source 13. The photosensitive material 5 is disposed at a predetermined distance F on the surface opposite to the laser irradiation side of the frosted glass 15, and a speckle pattern, which is a complicated interference pattern generated by the laser light transmitted and scattered by the frosted glass 15, is formed on the photosensitive material 5. Exposure exposure.
[0051]
At this time, since the ground glass 10 and the photosensitive material 5 are inclined at a predetermined angle α as shown in the figure, the speckle pattern is exposed in the photosensitive material at a predetermined angle. Since this angle corresponds to the slope of the portion having a different refractive index in the light scattering film (that is, the incident angle-dependent scattering peak angle θ), the angle is about 0 to 60 degrees depending on the application. Select appropriately within the range.
[0052]
The laser light source used for recording is appropriately selected from the wavelength of 647.9 nm, 514.5 nm, 488 nm, 457.9 nm, 413 nm, 364 nm or 351 nm of an argon ion laser or krypton ion laser depending on the sensitivity of the photosensitive material. Can be used. Other than argon ion and krypton ion lasers, any laser light source with good coherency can be used. For example, a helium neon laser or a semiconductor laser can be used.
[0053]
The speckle pattern is a bright and dark speckle pattern that occurs when light with good coherence is scattered or reflected or transmitted by a rough surface, and is generated because light scattered by minute irregularities on the rough surface interferes with an irregular phase relationship. Is.
[0054]
According to the description (p.266-p.268) of “Light Measurement Handbook published by Toshiharu Tamitsu published by Asakura Shoten et al., November 25, 1994”, speckles whose concentration and phase show random values depending on the position. In the pattern, the average size of the pattern is determined in inverse proportion to the angle at which the diffusion plate is viewed from the photosensitive material. Therefore, when the size of the diffusion plate is made larger in the vertical direction than in the horizontal direction, the pattern recorded on the photosensitive material is finer in the vertical direction than in the horizontal direction.
[0055]
The speckle pattern by the manufacturing method in the optical system of FIG. 6 has a wavelength λ of the laser beam to be used, a size D of the ground glass, and a distance F between the ground glass and the photosensitive material, and the average size d of the speckle pattern to be recorded. Generally, it is expressed by the following formula.
d = 1.2λF / D
The average length t of this speckle pattern in the depth direction is
t = 4.0λ (F / D)²
It is represented by
[0056]
As described above, the light scattering film of the present invention having a desired three-dimensional refractive index distribution can be obtained by optimizing the values of λ and F / D so as to have optimum scattering properties.
[0057]
As an example, when λ = 0.5 μm and F / D = 2, d = 1.2 μm and t = 8 μm, and the shading pattern on the film surface is distributed with an average of 1.2 μm, and in the film thickness direction, It is distributed with an average size of 8 μm in the direction according to the inclination angle.
[0058]
However, these sizes are only average sizes, and in fact, the portions with different refractive indexes of various sizes, mainly these sizes, are distributed on the surface and in the depth direction. Thus, the light scattering film of the present invention as shown in FIG. 2 is obtained.
[0059]
Hereinafter, embodiments of the present invention will be described with reference to specific examples.
[0060]
<Example 1>
Bisphenol-based epoxy resin epicoat 1004 (epoxy equivalent: 875-975, product name manufactured by Yuka Shell Epoxy Co., Ltd.) 100 parts by weight, tripropylene glycol diacrylate (VISCOAT-310HP, product name manufactured by Osaka Organic Chemical Co., Ltd.) 50 2 parts by weight and 3.0 parts by weight of 1-hydroxycyclohexyl phenyl ketone (IRGACURE 184, trade name, manufactured by Ciba Specialty Chemicals), 2 parts by weight of 10.0 parts of N-aminoethylpiperazine (N-AEP, manufactured by Koei Chemical Co., Ltd.) A solution obtained by mixing and dissolving in 160 parts by weight of butanone was used as a photosensitive solution. The photosensitive solution was applied to blue plate glass (1.1 mm thickness, 5 inch square) with a doctor blade and dried to obtain a recording medium.
[0061]
The recording medium was exposed from the surface of the recording material through the glass 15 with the optical system shown in FIG. 6 and light spread with an argon laser (364 nm) as a light source using a lens (α = 22 °, 20 mJ). / Cm²Then, after heating at 80 ° C. for 10 minutes, the whole surface was exposed with a UV light source (500 mJ / cm²). Furthermore, it heated at 150 degreeC for 60 minutes, and obtained the light-scattering film by peeling a hardened | cured material from a glass substrate. The resulting film had a thickness of 55 microns.
[0062]
Evaluation was made by measuring transmittance (wavelength range: 400 to 600 nm) at each angle with a spectrophotometer manufactured by Shimadzu Corporation. The results (total wavelength average transmittance) are shown in Table 1.
[0063]
[Table 1]

[0064]
<Example 2>
Implemented except using 100 parts by weight of bisphenol A type epoxy resin EP1007 (epoxy equivalent: 1750-2200, product name manufactured by Yuka Shell Epoxy Co., Ltd.) and 30 parts by weight of glycidyl phenyl ether instead of bisphenol epoxy resin Epicoat 1004 The light scattering film thus produced was obtained by operating in the same manner as in Example 1. The resulting film had a thickness of 31 microns. The results are shown in Table 2.
[0065]
[Table 2]

[0066]
<Example 3>
A produced light-scattering film was obtained in the same manner as in Example 2 except that dibromotolyl glycidyl ether (BROC, trade name, manufactured by Nippon Kayaku Co., Ltd.) was used instead of glycidyl phenyl ether. The resulting film thickness was 32 microns. The results are shown in Table 3.
[0067]
[Table 3]

[0068]
<Example 4>
Light scattering produced in the same manner as in Example 2 except that 10 parts by weight of methylendomethylenetetrahydrophthalic anhydride (Kayahard MCD, Nippon Kayaku Co., Ltd., trade name) was used instead of N-aminoethylpiperazine. A characteristic film was obtained. The resulting film had a thickness of 31 microns. The results are shown in Table 4.
[0069]
[Table 4]

[0070]
<Example 5>
Example 2 except that neopentyl glycol diacrylate (VISCOAT-215, trade name of Osaka Organic Chemical Co., Ltd.) was used instead of tripropylene glycol diacrylate (VISCOAT-310HP, trade name of Osaka Organic Chemical Co., Ltd.). The same light scattering film as above was obtained. The resulting film had a thickness of 29 microns. The results are shown in Table 5.
[0071]
[Table 5]

[0072]
<Example 6>
2-hydroxy-2-methyl-1-phenylpropan-2-one (DAROCURE 1173, Ciba Specialty) instead of 3.0 parts by weight of 1-hydroxycyclohexyl phenyl ketone (IRGACURE 184, trade name, manufactured by Ciba Specialty Chemicals) The product manufactured by Chemicals Co., Ltd.) was used in the same manner as in Example 1 except that 3.0 parts by weight was used to obtain a light-scattering film. The resulting film thickness was 32 microns. The results are shown in Table 6.
[0073]
[Table 6]

[0074]
<Example 7>
Instead of 100 parts by weight of bisphenol A type epoxy resin EP1007 (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.), 60 parts by weight of bisphenol A type epoxy resin EP1007 (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.) and brominated bisphenol A produced light-scattering film was obtained in the same manner as in Example 2 except that a mixed system of 40 parts by weight of A-type epoxy resin YL6167 (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.) was used. The resulting film had a thickness of 29 microns. The results are shown in Table 7.
[0075]
[Table 7]

[0076]
<Example 8>
Instead of 3.0 parts by weight of 1-hydroxycyclohexyl phenyl ketone (IRGACURE184, trade name, manufactured by Ciba Specialty Chemicals), 4.0 parts by weight of 4,4′-bis (tert-butylphenyl) iodonium hexafluorophosphate Example 1 except that 0.25 parts by weight of 1- (p-methoxyphenyl) -3- (p-dimethylaminophenyl) -2-propen-1-one and krypton laser (413 nm) are used as the light source In the same manner as described above, a light-scattering film was produced. The resulting film had a thickness of 70 microns. The results are shown in Table 8.
[0077]
[Table 8]

[0078]
【The invention's effect】
If this composition is used, light scattering occurs for light incident at a predetermined angle, and conversely, it functions as a transparent film for light perpendicular thereto, thereby providing light scattering with incident angle selectivity. Therefore, light that needs to be scattered and light that does not need to be scattered can be separated by the incident angle on the film, resulting in unnecessary scattering when used in a display device. In addition, a light scattering film having effects such as improving display brightness, fineness, and contrast and reducing blurring of a display image can be produced.
[0079]
Further, when light is incident at an incident angle at which light scattering occurs, it is possible to produce a film having scattering anisotropy in which the spread of the scattered light differs vertically and horizontally. Therefore, it is possible to emit scattered light only in a necessary direction. As a result, when used in a display device or the like, there is an effect of improving display brightness and contrast without causing unnecessary scattering.
[0080]
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a light scattering film of the present invention, wherein a left side is a plan view and a right side is a cross-sectional view.
FIG. 2 is an explanatory view showing a light scattering film of the present invention, with the left side being a plan view and the right being a cross-sectional view.
FIG. 3 is a graph showing an example of incident angle dependency of the light scattering film of the present invention.
FIG. 4 is an explanatory diagram for explaining the light scattering anisotropy of the light scattering film of the present invention.
FIG. 5 is an explanatory view showing an example of an optical system for producing a light scattering film having the structure shown in FIG. 1 by using a mask pattern.
6 is an explanatory view showing an example of an optical system for producing the light scattering film having the structure shown in FIG. 2 using a speckle pattern. FIG.
[Explanation of symbols]
1. Light scattering film
2. Illumination light incident from the scattering direction
3. Illumination light incident from the transmission direction
4 ... Plot of measured haze values
5 ... Sensitive material
6 ... UV light source
7. Collimate optical system
8 ... Parallel light
9 ... Mask original
10 ... Glass substrate
11 ... chrome pattern
12 ... Optical fiber
13 ... Laser light source
14 ... Laser light
15 ... ground glass
16 ... Beam expander
17 ... Collimator

Claims (9)

At least (A) a bisphenol A type epoxy resin or a brominated bisphenol A type epoxy resin represented by the general formula (I);
(B) a radically polymerizable compound containing at least one ethylenically unsaturated bond in the structural unit;
(C) a photopolymerization initiator that generates radical species by actinic radiation;
(D) consists of an epoxy curing agent,
A composition for anisotropic light-scattering films, characterized in that, at room temperature, the refractive index of the compound (B) having radical polymerizability is lower than that of (A) bisphenol A type epoxy resin or brominated bisphenol A type epoxy resin.

<Image of (Chemical Formula 1)>
(R represents a hydrogen atom or a bromine atom. N represents a natural number.) (E) An aromatic compound having a refractive index higher than that of the radically polymerizable compound (B) at room temperature and having at least one glycidyl group in the molecule is added. The composition for anisotropic light-scattering films as described.   The composition for anisotropic light scattering film according to claim 1, wherein the bisphenol A type epoxy resin or brominated bisphenol A type epoxy resin (A) has an epoxy equivalent of 400 to 2200.   The compound (B) having radical polymerizability is a compound having at least one ethylenically unsaturated bond having a liquid at normal temperature and normal pressure and a boiling point of 100 ° C. or higher at normal pressure. The composition for anisotropic light scattering films according to claim 1.   20 to 80 parts by weight of the compound (B) having radical polymerizability is mixed with 100 parts by weight of the bisphenol A type epoxy resin or brominated bisphenol A type epoxy resin (A). The composition for anisotropic light scattering films according to claim 1.   The photopolymerization initiator that generates radical species by (C) actinic radiation is any one of α-hydroxy ketones, α-amino ketones, bisacylphosphine oxides, iron arene complexes, sulfonium salts, and iodonium salts. The composition for anisotropic light-scattering films according to claim 1.   The anisotropic light-scattering film composition according to claim 1, wherein the (D) epoxy curing agent is any one of amines, boron trifluoride complex compounds, and acid anhydrides.   The composition for anisotropic light-scattering films according to claim 1, comprising a sensitizing dye (F) selected from (melo) cyanine derivatives, coumarin derivatives, chalcone derivatives, and (thio) xanthene derivatives.   An anisotropic light-scattering film comprising the composition for anisotropic light-scattering film according to claim 1.

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