JP4467039B2 - Liquid crystal film, method for producing liquid crystal alignment film, and image display device - Google Patents

Description

（ただし、Ｒ¹ は水素原子またはメチル基を、ａは１〜６の正の整数を、Ｘ¹ は−ＣＯ₂ −基または−ＯＣＯ−基を、Ｒ² はシアノ基、アルコキシ基、フルオロ基またはアルキル基を、ｂおよびｃはそれぞれ１または２の整数を示す。）で表されるモノマーユニットを有するものあげられる。
【００３６】
また、前記一般式（ａ）で表されるモノマーユニットおよび下記一般式（ｂ）で表されるモノマーユニットを有するものがあげられる。前記モノマーユニット（ｂ）としては、たとえば、一般式（ｂ）：
【化２】

（ただし、Ｒ³ は水素原子またはメチル基を、Ｘ² は−ＣＯ₂ −基または−ＯＣＯ−基、−Ｏ−または単結合を、Ｒ⁴ は一般式（ｃ）：
【化３】

で表される置換基を示す。Ｒ⁵ はシアノ基、アルコキシ基、フルオロ基またはアルキル基）で表されるモノマーユニットがあげられる。
【００３７】
また、モノマーユニット（ａ）とモノマーユニット（ｂ）の割合は、特に制限されるものではなく、モノマーユニットの種類にもよって異なるが、モル比で、（ｂ）／｛（ａ）＋（ｂ）｝＜０．８である。さらには（ｂ）／｛（ａ）＋（ｂ）｝＝０〜０．７５、さらには０．２〜０．７であるのが好ましい。
【００３８】
前記液晶層（２）は、基材フィルム（１）上に液晶モノマーを、塗布し、硬化することにより得られる液晶ポリマーにより形成することができる。液晶モノマーは、重合後に、ネマチック性、コレステリック性またはスメクチック性の液晶配向を示す液晶ポリマーになるものが適宜に選択して用いられる。一般に、液晶モノマーは、前記同様の液晶配向を示す各種骨格を有し、かつ末端に、アクリロイル基、メタクリロイル基、ビニル基等の不飽和二重結合やエポキシ基等の重合性官能基を少なくとも１つ有する液晶性化合物である。液晶層（２）の耐久性を向上させるためは、液晶モノマーとして重合性官能基を２つ以上有するものを用い、重合とともに架橋させることができる。なお、液晶モノマーとしては、重合後にネマチック配向性を示すものが好ましい。
【００３９】
液晶モノマー中には、通常、重合開始剤を含有する。重合開始剤は、液晶モノマーの重合方法に応じたものが適宜に選択される。液晶モノマーの重合方法としては、たとえば、紫外線重合があげられ、この場合には光重合開始剤が用いられる。光重合開始剤としては、たとえば、チバスペシャルティケミカルズ社製のイルガキュア（Ｉｒｇａｃｕｒｅ）９０７，同１８４、同６５１、同３６９などを例示できる。光重合開始剤の添加量は、重合性液晶モノマーの種類等を考慮して、配向性を乱さない程度に加えられる。通常、重合性液晶モノマー１００重量部に対して０．５〜３０重量部程度が好ましい。特に３重量部以上が好ましい。
【００４０】
基材フィルム（１）としては、液晶層（２）を形成できるもの透明基材を特に制限なく使用できる。たとえば、単層または積層の各種プラスチックフィルムやガラス板、金属等を使用できる。プラスチックフィルムとしては、たとえば、ポリエチレンテレフタレート、ポリエチレンナフタレート等のポリエステル系ポリマー、ジアセチルセルロース、トリアセチルセルロース等のセルロース系ポリマー、ポリカーボネート系ポリマー、ポリメチルメタクリレート等のアクリル系ポリマー等の透明ポリマーからなるフィルムがあげられる。またポリスチレン、アクリロニトリル・スチレン共重合体等のスチレン系ポリマー、ポリエチレン、ポリプロピレン、環状ないしノルボルネン構造を有するポリオレフィン、エチレン・プロピレン共重合体等のオレフィン系ポリマー、塩化ビニル系ポリマー、ナイロンや芳香族ポリアミド等のアミド系ポリマー等の透明ポリマーからなるフィルムもあげられる。さらにイミド系ポリマー、スルホン系ポリマー、ポリエーテルスルホン系ポリマー、ポリエーテルエーテルケトン系ポリマー、ポリフェニレンスルフィド系ポリマー、ビニルアルコール系ポリマー、塩化ビニリデン系ポリマー、ビニルブチラール系ポリマー、アリレート系ポリマー、ポリオキシメチレン系ポリマー、エポキシ系ポリマーや前記ポリマーのブレンド物等の透明ポリマーからなるフィルムなどもあげられる。
【００４１】
また、基材フィルム（１）は配向基材とすることができる。配向基材としては、従来より知られている各種のものを使用できる。たとえば、前記透明基材上にポリイミドやポリビニルアルコール等からなる薄層の配向膜を形成してそれをラビングする方法により形成したもの、透明基材を延伸処理した延伸フィルム、シンナメート骨格やアゾベンゼン骨格を有するポリマーまたはポリイミドに偏光紫外線を照射したもの等を用いることができる。基材フィルム（１）を配向基材とする場合には、透明基材を延伸処理した延伸フィルムを用いるのが好ましい。特に二軸延伸ポリエチレンテレフタレートフィルムが好ましい。
【００４２】
なお、液晶層（２）の形成法は、特に制限されない。前記液晶モノマー、液晶ポリマーの塗布は、これらを溶媒に溶解した溶液を用いる溶液塗布、または溶融塗布のいずれの方法を採用することもできる。
【００４３】
前記液晶ポリマー、液晶モノマーの溶液を調製する際に用いられる溶媒は、液晶ポリマー、液晶モノマー等の種類により異なり適宜に決定される。たとえば、通常、クロロホルム、ジクロロメタン、ジクロロエタン、テトラクロロエタン、トリクロロエチレン、テトラクロロエチレン、クロロベンゼンなどのハロゲン化炭化水素類、フェノール、パラクロロフェノールなどのフェノール類、ベンゼン、トルエン、キシレン、メトキシベンゼン、１，２−ジメトキベンゼンなどの芳香族炭化水素類、その他、アセトン、酢酸エチル、ｔｅｒｔ−ブチルアルコール、グリセリン、エチレングリコール、トリエチレングリコール、エチレングリコールモノメチルエーテル、ジエチレングリコールジメチルエーテル、エチルセルソルブ、ブチルセルソルブ、２−ピロリドン、Ｎ−メチル−２−ピロリドン、ピリジン、トリエチルアミン、テトラヒドロフラン、ジメチルホルムアミド、ジメチルアセトアミド、ジメチルスルホキシド、アセトニトリル、ブチロニトリル、二硫化炭素、シクロヘキサノンなどを用いることができる。溶液の濃度は、液晶ポリマー、液晶モノマー等の溶解性や液晶層（２）の膜厚に依存し、適宜に決定できる。通常３〜５０重量％、好ましくは７〜３０重量％の範囲である。
【００４４】
上記の溶媒を用いて所望の濃度に調整した前記の溶液の塗布方法としては、例えば、ロールコート法、グラビアコート法、バーコート法などを採用することが好ましい。塗布後、溶媒を除去し、液晶層（２）を形成させる。溶媒の除去条件は、特に限定されず、溶媒をおおむね除去でき、液晶層が流動したり、流れ落ちたりさえしなければ良い。通常、室温での乾燥、乾燥炉での乾燥、ホットプレート上での加熱などを利用して溶媒を除去する。
【００４５】
液晶層（２）を配向させる場合には、液晶ポリマーまたは液晶モノマーが液晶状態を示す温度において、熱処理により行う。当該熱処理温度は、液晶ポリマーまたは液晶モノマーにより適宜に調整する。熱処理方法としては、上記の乾燥方法と同様の方法で行うことができる。また熱処理時間は、熱処理温度および前記液晶ポリマーまたは液晶モノマーにより異なるため一概には言えないが、通常１０秒〜２時間、好ましくは２０秒〜３０分の範囲で選択される。
【００４６】
なお、液晶層（２）を、液晶モノマーにより形成する場合には、その重合法は液晶モノマーの種類に応じて各種手段を採用できるが、たとえば、光照射による光重合性法を採用できる。光照射は、たとえば、紫外線照射により行う。紫外線照射条件は、十分に反応を促進するために、不活性気体雰囲気中とすることが好ましい。高圧水銀紫外ランプが代表的に用いられる。メタハライドＵＶランプや白熱管などの別種ランプを使用することもできる。なお、紫外線照射時の液晶層表面温度が液晶温度範囲内になるように、コールドミラー、水冷その他の冷却処理あるいはライン速度を速くするなどして適宜に調整する。
【００４７】
また液晶層（２）の厚さは、特に制限されないが、通常１〜２０μｍ程度、さらには２〜１０μｍの範囲で調整するのが好ましい。なお、液晶層（２）は１層形成することもでき、さらには多層形成することもできる。
【００４８】
上記のようにして、基材フィルム（１）上に液晶層（２）を設けた液晶フィルム（Ａ）を調製しておく。当該液晶フィルム（Ａ）の液晶層（２）は、他の基材に転写可能である。他の基材は、用途に応じて適宜に決定できるが、配向基材（３）が好適である。
【００４９】
配向基材（３）は、特に制限されず、従来より用いれているものを特に制限なく使用できる。たとえば、基材フィルム（１）を配向基材とする場合に説明したものと同様のものがあげられる。配向基材（３）としては、前記透明基材上にポリイミドやポリビニルアルコール等からなる薄層の配向膜を形成してそれをラビングする方法により形成したもの、シンナメート骨格やアゾベンゼン骨格を有するポリマーまたはポリイミドに偏光紫外線を照射したもの等を用いるのが好ましい。なお、配向基材（３）への配向方向が互いに異なる２方向の領域の形成は、ガラス基板等の透明基材にフォトマスク等を利用してポリイミド等により形成することができる。
【００５０】
前記配向基材（３）への転写が可能な、液晶フィルム（Ａ）は、液晶配向フィルムの作製に供される。まず、前記液晶フィルム（Ａ）の液晶層（２）を、配向基材（３）に熱ラミネーションする。
【００５１】
熱ラミネーションは、液晶層（２）を形成している液晶ポリマーのガラス転移点以上の温度で行なう。通常は、液晶ポリマーのガラス転移点よりも、＋２０〜＋１５０℃程度、さらに＋３０〜＋１２０℃である。なお、熱ラミネーションとしては、ラミネートロール自体を加熱する方法、ラミネート直前まで貼り合わせるものを加熱する方法等を採用できる。
【００５２】
次いで、前記液晶ポリマーのガラス転移点以下に冷却してから、基材フィルム（１）を剥離する。冷却は、ガラス転移点よりも、−１０〜−１５０℃程度、さらに−２０〜−１００℃になるまで行なうのが好ましい。冷却は、ガラス転移点以下の雰囲気下に放置することにより行なうことができる。また空冷、水冷等の強制冷却をすうこともできる。基材フィルム（１）の剥離によって、配向基材（３）に液晶層（２）が転写される。
【００５３】
次いで、前記液晶ポリマーのガラス転移点以上の温度に再加熱を行って、前記配向基材上（３）で液晶層（２）を配向させ、液晶配向層（２′）にする。
【００５４】
なお、再加熱温度が高くなるとコスト増になること、また高温になりすぎると等方相を有するものがあるため、再加熱は、液晶ポリマーが等方相にならない範囲で行なわれる。再加熱は、通常は、ガラス転移点よりも、＋２０〜＋１５０℃程度、さらに＋３０〜＋１２０℃である。再加熱時間は、１〜６００秒間程度、さらには１０〜３００秒間程度とするのが好ましい。
【００５５】
次いで、前記液晶ポリマーのガラス転移点以下の温度に冷却して、液晶配向層（２′）の配向を固定化する。ネマチック液晶ポリマーの場合には、ネマチック構造が固定化される。こうして、配向基材（３）に、配向が固定された液晶配向層（２′）を有する液晶配向フィルムが得られる。
【００５６】
前記液晶配向フィルムは、前記配向基材（３）とともに用いることができ、また配向基材（３）から剥離して、光学フィルムとして用いることができる。さらには別の光学フィルムに転写して用いることもできる。前記液晶配向フィルムは単独でまたは他のフィルムと組み合わせて、位相差板、視角補償フィルム、光学補償フィルム、楕円偏光フィルム等の光学フィルムとして使用できる。以下これらについて説明する。
【００５７】
液晶表示装置等の画像表示装置に適用される光学フィルムには偏光板が用いられる。偏光板は、通常、偏光子の片側または両側に保護フィルムを有するものである。偏光子は、特に制限されず、各種のものを使用できる。偏光子としては、たとえば、ポリビニルアルコール系フィルム、部分ホルマール化ポリビニルアルコール系フィルム、エチレン・酢酸ビニル共重合体系部分ケン化フィルム等の親水性高分子フィルムに、ヨウ素や二色性染料等の二色性物質を吸着させて一軸延伸したもの、ポリビニルアルコールの脱水処理物やポリ塩化ビニルの脱塩酸処理物等のポリエン系配向フィルム等があげられる。これらのなかでもポリビニルアルコール系フィルムを延伸して二色性材料（沃素、染料）を吸着・配向したものが好適に用いられる。偏光子の厚さも特に制限されないが、５〜８０μｍ程度が一般的である。
【００５８】
ポリビニルアルコール系フィルムをヨウ素で染色し一軸延伸した偏光子は、たとえば、ポリビニルアルコールをヨウ素の水溶液に浸漬することによって染色し、元長の３〜７倍に延伸することで作製することができる。必要に応じてホウ酸やヨウ化カリウムなどの水溶液に浸漬することもできる。さらに必要に応じて染色の前にポリビニルアルコール系フィルムを水に浸漬して水洗してもよい。ポリビニルアルコール系フィルムを水洗することでポリビニルアルコール系フィルム表面の汚れやブロッキング防止剤を洗浄することができるほかに、ポリビニルアルコール系フィルムを膨潤させることで染色のムラなどの不均一を防止する効果もある。延伸はヨウ素で染色した後に行っても良いし、染色しながら延伸してもよし、また延伸してからヨウ素で染色してもよい。ホウ酸やヨウ化カリウムなどの水溶液中や水浴中でも延伸することができる。
【００５９】
前記偏光子の片側または両側に設けられている保護フィルムには、透明性、機械的強度、熱安定性、水分遮蔽性、等方性などに優れるものが好ましい。前記保護フィルムの材料としては、例えばポリエチレンテレフタレートやポリエチレンナフタレート等のポリエステル系ポリマー、ジアセチルセルロースやトリアセチルセルロース等のセルロース系ポリマー、ポリメチルメタクリレート等のアクリル系ポリマー、ポリスチレンやアクリロニトリル・スチレン共重合体（ＡＳ樹脂）等のスチレン系ポリマー、ポリカーボネート系ポリマーなどがあげられる。また、ポリエチレン、ポリプロピレン、シクロ系ないしはノルボルネン構造を有するポリオレフィン、エチレン・プロピレン共重合体の如きポリオレフィン系ポリマー、塩化ビニル系ポリマー、ナイロンや芳香族ポリアミド等のアミド系ポリマー、イミド系ポリマー、スルホン系ポリマー、ポリエーテルスルホン系ポリマー、ポリエーテルエーテルケトン系ポリマー、ポリフェニレンスルフィド系ポリマー、ビニルアルコール系ポリマー、塩化ビニリデン系ポリマー、ビニルブチラール系ポリマー、アリレート系ポリマー、ポリオキシメチレン系ポリマー、エポキシ系ポリマー、あるいは前記ポリマーのブレンド物などが保護フィルムを形成するポリマーの例としてあげられる。その他、アクリル系やウレタン系、アクリルウレタン系やエポキシ系、シリコーン系等の熱硬化型ないし紫外線硬化型樹脂などをフィルム化したものなどがあげられる。
【００６０】
また、特開２００１−３４３５２９号公報（ＷＯ０１／３７００７）に記載のポリマーフィルム、たとえば、（Ａ）側鎖に置換および／または非置換イミド基を有する熱可塑性樹脂と、（Ｂ）側鎖に置換および／非置換フェニルならびにニトリル基を有する熱可塑性樹脂を含有する樹脂組成物があげられる。具体例としてはイソブチレンとＮ−メチルマレイミドからなる交互共重合体とアクリロニトリル・スチレン共重合体とを含有する樹脂組成物のフィルムがあげられる。フィルムは樹脂組成物の混合押出品などからなるフィルムを用いることができる。
【００６１】
偏光特性や耐久性などの点より、特に好ましく用いることができる保護フィルムは、表面をアルカリなどでケン化処理したトリアセチルセルロースフィルムである。透明保護層の厚さは、任意であるが一般には偏光板の薄型化などを目的に５００μｍ以下、さらには１〜３００μｍ、特に５〜３００μｍが好ましい。なお、偏光子の両側に保護フィルムを設ける場合は、その表裏で異なるポリマー等からなる透明保護フィルムを用いるができる。
【００６２】
また、透明保護フィルムは、できるだけ色付きがないことが好ましい。したがって、Ｒｔｈ＝［（ｎｘ＋ｎｙ）／２−ｎｚ］・ｄ（ただし、ｎｘ、ｎｙはフィルム平面内の主屈折率、ｎｚはフィルム厚方向の屈折率、ｄはフィルム厚みである）で表されるフィルム厚み方向の位相差値が−９０ｎｍ〜＋７５ｎｍである保護フィルムが好ましく用いられる。かかる厚み方向の位相差値（Ｒｔｈ）が−９０ｎｍ〜＋７５ｎｍのものを使用することにより、保護フィルムに起因する偏光板の着色（光学的な着色）をほぼ解消することができる。厚み方向位相差値（Ｒｔｈ）は、さらに好ましくは−８０ｎｍ〜＋６０ｎｍ、特に−７０ｎｍ〜＋４５ｎｍが好ましい。
【００６３】
前記偏光子と保護フィルムとは通常、水系粘着剤等を介して密着している。水系接着剤としては、ポリビニルアルコール系接着剤、ゼラチン系接着剤、ビニル系ラテックス系、水系ポリウレタン、水系ポリエステル等を例示できる。
【００６４】
前記保護フィルムとしては、ハードコート層や反射防止処理、スティッキング防止や、拡散ないしアンチグレアを目的とした処理を施したものを用いることができる。
【００６５】
ハードコート処理は偏光板表面の傷付き防止などを目的に施されるものであり、例えばアクリル系、シリコーン系などの適宜な紫外線硬化型樹脂による硬度や滑り特性等に優れる硬化皮膜を保護フィルムの表面に付加する方式などにて形成することができる。反射防止処理は偏光板表面での外光の反射防止を目的に施されるものであり、従来に準じた反射防止膜などの形成により達成することができる。また、スティッキング防止処理は隣接層との密着防止を目的に施される。
【００６６】
またアンチグレア処理は偏光板の表面で外光が反射して偏光板透過光の視認を阻害することの防止等を目的に施されるものであり、例えばサンドブラスト方式やエンボス加工方式による粗面化方式や透明微粒子の配合方式などの適宜な方式にて保護フィルムの表面に微細凹凸構造を付与することにより形成することができる。前記表面微細凹凸構造の形成に含有させる微粒子としては、例えば平均粒径が０．５〜５０μｍのシリカ、アルミナ、チタニア、ジルコニア、酸化錫、酸化インジウム、酸化カドミウム、酸化アンチモン等からなる導電性のこともある無機系微粒子、架橋又は未架橋のポリマー等からなる有機系微粒子などの透明微粒子が用いられる。表面微細凹凸構造を形成する場合、微粒子の使用量は、表面微細凹凸構造を形成する透明樹脂１００重量部に対して一般的に２〜５０重量部程度であり、５〜２５重量部が好ましい。アンチグレア層は、偏光板透過光を拡散して視角などを拡大するための拡散層（視角拡大機能など）を兼ねるものであってもよい。
【００６７】
なお、前記反射防止層、スティッキング防止層、拡散層やアンチグレア層等は、保護フィルムそのものに設けることができるほか、別途光学層として透明保護層とは別体のものとして設けることもできる。
【００６８】
前記偏光板は、位相差板を積層された楕円偏光板または円偏光板として用いることができる。前記楕円偏光板または円偏光板について説明する。これらは位相差板により直線偏光を楕円偏光または円偏光に変えたり、楕円偏光または円偏光を直線偏光に変えたり、あるいは直線偏光の偏光方向を変える。特に、直線偏光を円偏光に変えたり、円偏光を直線偏光に変える位相差板としては、いわゆる１／4 波長板（λ／4 板とも言う）が用いられる。１／2 波長板（λ／2 板とも言う）は、通常、直線偏光の偏光方向を変える場合に用いられる。
【００６９】
楕円偏光板はスーパーツイストネマチック（ＳＴＮ）型液晶表示装置の液晶層の複屈折により生じた着色（青又は黄）を補償（防止）して、前記着色のない白黒表示する場合などに有効に用いられる。更に、三次元の屈折率を制御したものは、液晶表示装置の画面を斜め方向から見た際に生じる着色も補償（防止）することができて好ましい。円偏光板は、例えば画像がカラー表示になる反射型液晶表示装置の画像の色調を整える場合などに有効に用いられ、また、反射防止の機能も有する。
【００７０】
位相差板には、例えば各種波長板や液晶層の複屈折による着色や視角等の補償を目的としたものなどを使用することができ、また使用目的に応じた適宜な位相差を有する２種以上の位相差板を積層して位相差等の光学特性を制御することができる。位相差板としては、ポリカーボネート、ノルボルネン系樹脂、ポリビニルアルコール、ポリスチレン、ポリメチルメタクリレート、ポリプロピレンやその他のポリオレフィン、ポリアリレート、ポリアミドの如き適宜なポリマーからなるフィルムを延伸処理してなる複屈折性フィルムや液晶ポリマーなどの液晶材料からなる配向フィルム、液晶材料の配向層をフィルムにて支持したものなどがあげられる。
【００７１】
また視角補償フィルムとして偏光板に積層して広視野角偏光板として用いられる。視角補償フィルムは、液晶表示装置の画面を、画面に垂直でなくやや斜めの方向から見た場合でも、画像が比較的鮮明にみえるように視野角を広げるためのフィルムである。
【００７２】
このような視角補償位相差板としては、他に二軸延伸処理や直交する二方向に延伸処理等された複屈折を有するフィルム、傾斜配向フィルムのような二方向延伸フィルムなどが用いられる。傾斜配向フィルムとしては、例えばポリマーフィルムに熱収縮フィルムを接着して加熱によるその収縮力の作用下にポリマーフィルムを延伸処理又は／及び収縮処理したものや、液晶ポリマーを斜め配向させたものなどが挙げられる。視角補償フィルムは、液晶セルによる位相差に基づく視認角の変化による着色等の防止や良視認の視野角の拡大などを目的として適宜に組み合わせることができる。
【００７３】
また良視認の広い視野角を達成する点などより、液晶ポリマーの配向層、特にディスコティック液晶ポリマーの傾斜配向層からなる光学的異方性層をトリアセチルセルロースフィルムにて支持した光学補償位相差板が好ましく用いうる。
【００７４】
前記のほか実用に際して積層される光学層については特に限定はないが、例えば反射板や半透過板などの液晶表示装置等の形成に用いられることのある光学層を１層または２層以上用いることができる。特に、楕円偏光板または円偏光板に、更に反射板または半透過反射板が積層されてなる反射型偏光板または半透過型偏光板、あるいは偏光板に更に輝度向上フィルムが積層されてなる偏光板があげられる。
【００７５】
反射型偏光板は、偏光板に反射層を設けたもので、視認側（表示側）からの入射光を反射させて表示するタイプの液晶表示装置などを形成するためのものであり、バックライト等の光源の内蔵を省略できて液晶表示装置の薄型化を図りやすいなどの利点を有する。反射型偏光板の形成は、必要に応じ透明保護層等を介して偏光板の片面に金属等からなる反射層を付設する方式などの適宜な方式にて行うことができる。
【００７６】
反射型偏光板の具体例としては、必要に応じマット処理した保護フィルムの片面に、アルミニウム等の反射性金属からなる箔や蒸着膜を付設して反射層を形成したものなどがあげられる。また前記保護フィルムに微粒子を含有させて表面微細凹凸構造とし、その上に微細凹凸構造の反射層を有するものなどもあげられる。前記した微細凹凸構造の反射層は、入射光を乱反射により拡散させて指向性やギラギラした見栄えを防止し、明暗のムラを抑制しうる利点などを有する。また微粒子含有の保護フィルムは、入射光及びその反射光がそれを透過する際に拡散されて明暗ムラをより抑制しうる利点なども有している。保護フィルムの表面微細凹凸構造を反映させた微細凹凸構造の反射層の形成は、例えば真空蒸着方式、イオンプレーティング方式、スパッタリング方式等の蒸着方式やメッキ方式などの適宜な方式で金属を透明保護層の表面に直接付設する方法などにより行うことができる。
【００７７】
反射板は前記の偏光板の保護フィルムに直接付与する方式に代えて、その透明フィルムに準じた適宜なフィルムに反射層を設けてなる反射シートなどとして用いることもできる。なお反射層は、通常、金属からなるので、その反射面が保護フィルムや偏光板等で被覆された状態の使用形態が、酸化による反射率の低下防止、ひいては初期反射率の長期持続の点や、保護層の別途付設の回避の点などより好ましい。
【００７８】
なお、半透過型偏光板は、上記において反射層で光を反射し、かつ透過するハーフミラー等の半透過型の反射層とすることにより得ることができる。半透過型偏光板は、通常液晶セルの裏側に設けられ、液晶表示装置などを比較的明るい雰囲気で使用する場合には、視認側（表示側）からの入射光を反射させて画像を表示し、比較的暗い雰囲気においては、半透過型偏光板のバックサイドに内蔵されているバックライト等の内蔵光源を使用して画像を表示するタイプの液晶表示装置などを形成できる。すなわち、半透過型偏光板は、明るい雰囲気下では、バックライト等の光源使用のエネルギーを節約でき、比較的暗い雰囲気下においても内蔵光源を用いて使用できるタイプの液晶表示装置などの形成に有用である。
【００７９】
偏光板と輝度向上フィルムを貼り合わせた偏光板は、通常液晶セルの裏側サイドに設けられて使用される。輝度向上フィルムは、液晶表示装置などのバックライトや裏側からの反射などにより自然光が入射すると所定偏光軸の直線偏光または所定方向の円偏光を反射し、他の光は透過する特性を示すもので、輝度向上フィルムを偏光板と積層した偏光板は、バックライト等の光源からの光を入射させて所定偏光状態の透過光を得ると共に、前記所定偏光状態以外の光は透過せずに反射される。この輝度向上フィルム面で反射した光を更にその後ろ側に設けられた反射層等を介し反転させて輝度向上フィルムに再入射させ、その一部又は全部を所定偏光状態の光として透過させて輝度向上フィルムを透過する光の増量を図ると共に、偏光子に吸収させにくい偏光を供給して液晶表示画像表示等に利用しうる光量の増大を図ることにより輝度を向上させうるものである。すなわち、輝度向上フィルムを使用せずに、バックライトなどで液晶セルの裏側から偏光子を通して光を入射した場合には、偏光子の偏光軸に一致していない偏光方向を有する光は、ほとんど偏光子に吸収されてしまい、偏光子を透過してこない。すなわち、用いた偏光子の特性によっても異なるが、およそ５０％の光が偏光子に吸収されてしまい、その分、液晶画像表示等に利用しうる光量が減少し、画像が暗くなる。輝度向上フィルムは、偏光子に吸収されるような偏光方向を有する光を偏光子に入射させずに輝度向上フィルムで一旦反射させ、更にその後ろ側に設けられた反射層等を介して反転させて輝度向上フィルムに再入射させることを繰り返し、この両者間で反射、反転している光の偏光方向が偏光子を通過し得るような偏光方向になった偏光のみを、輝度向上フィルムは透過させて偏光子に供給するので、バックライトなどの光を効率的に液晶表示装置の画像の表示に使用でき、画面を明るくすることができる。
【００８０】
輝度向上フィルムと上記反射層等の間に拡散板を設けることもできる。輝度向上フィルムによって反射した偏光状態の光は上記反射層等に向かうが、設置された拡散板は通過する光を均一に拡散すると同時に偏光状態を解消し、非偏光状態となる。すなわち、拡散板は偏光を元の自然光状態にもどす。この非偏光状態、すなわち自然光状態の光が反射層等に向かい、反射層等を介して反射し、再び拡散板を通過して輝度向上フィルムに再入射することを繰り返す。このように輝度向上フィルムと上記反射層等の間に、偏光を元の自然光状態にもどす拡散板を設けることにより表示画面の明るさを維持しつつ、同時に表示画面の明るさのむらを少なくし、均一で明るい画面を提供することができる。かかる拡散板を設けることにより、初回の入射光は反射の繰り返し回数が程よく増加し、拡散板の拡散機能と相俟って均一の明るい表示画面を提供することができたものと考えられる。
【００８１】
前記輝度向上フィルムとしては、例えば誘電体の多層薄膜や屈折率異方性が相違する薄膜フィルムの多層積層体の如き、所定偏光軸の直線偏光を透過して他の光は反射する特性を示すもの、コレステリック液晶ポリマーの配向フィルムやその配向液晶層をフィルム基材上に支持したものの如き、左回り又は右回りのいずれか一方の円偏光を反射して他の光は透過する特性を示すものなどの適宜なものを用いうる。
【００８２】
従って、前記した所定偏光軸の直線偏光を透過させるタイプの輝度向上フィルムでは、その透過光をそのまま偏光板に偏光軸を揃えて入射させることにより、偏光板による吸収ロスを抑制しつつ効率よく透過させることができる。一方、コレステリック液晶層の如く円偏光を透過するタイプの輝度向上フィルムでは、そのまま偏光子に入射させることもできるが、吸収ロスを抑制する点よりその円偏光を位相差板を介し直線偏光化して偏光板に入射させることが好ましい。なお、その位相差板として１／４波長板を用いることにより、円偏光を直線偏光に変換することができる。
【００８３】
可視光域等の広い波長範囲で１／４波長板として機能する位相差板は、例えば波長５５０ｎｍの淡色光に対して１／４波長板として機能する位相差層と他の位相差特性を示す位相差層、例えば１／２波長板として機能する位相差層とを重畳する方式などにより得ることができる。従って、偏光板と輝度向上フィルムの間に配置する位相差板は、１層又は２層以上の位相差層からなるものであってよい。
【００８４】
なお、コレステリック液晶層についても、反射波長が相違するものの組み合わせにして２層又は３層以上重畳した配置構造とすることにより、可視光領域等の広い波長範囲で円偏光を反射するものを得ることができ、それに基づいて広い波長範囲の透過円偏光を得ることができる。
【００８５】
また、偏光板は、上記の偏光分離型偏光板の如く、偏光板と２層又は３層以上の光学層とを積層したものからなっていてもよい。従って、上記の反射型偏光板や半透過型偏光板と位相差板を組み合わせた反射型楕円偏光板や半透過型楕円偏光板などであってもよい。
【００８６】
上記の楕円偏光板や反射型楕円偏光板は、偏光板又は反射型偏光板と位相差板を適宜な組合せで積層したものである。かかる楕円偏光板等は、（反射型）偏光板と位相差板の組合せとなるようにそれらを液晶表示装置の製造過程で順次別個に積層することよって形成することができるが、予め積層して楕円偏光板等の光学フィルムとしたのものは、品質の安定性や積層作業性等に優れて液晶表示装置などの製造効率を向上させうる利点がある。
【００８７】
本発明の光学フィルムには、粘着層を設けることもできる。粘着剤層は、液晶セルへの貼着に用いることができる他、光学層の積層に用いられる。前記光学フィルムの接着に際し、それらの光学軸は目的とする位相差特性などに応じて適宜な配置角度とすることができる。
【００８８】
粘着層を形成する粘着剤は特に制限されないが、例えばアクリル系重合体、シリコーン系ポリマー、ポリエステル、ポリウレタン、ポリアミド、ポリエーテル、フッ素系やゴム系などのポリマーをベースポリマーとするものを適宜に選択して用いることができる。特に、アクリル系粘着剤の如く光学的透明性に優れ、適度な濡れ性と凝集性と接着性の粘着特性を示して、耐候性や耐熱性などに優れるものが好ましく用いうる。
【００８９】
また上記に加えて、吸湿による発泡現象や剥がれ現象の防止、熱膨張差等による光学特性の低下や液晶セルの反り防止、ひいては高品質で耐久性に優れる液晶表示装置の形成性などの点より、吸湿率が低くて耐熱性に優れる粘着層が好ましい。
【００９０】
粘着層は、例えば天然物や合成物の樹脂類、特に、粘着性付与樹脂や、ガラス繊維、ガラスビーズ、金属粉、その他の無機粉末等からなる充填剤や顔料、着色剤、酸化防止剤などの粘着層に添加されることの添加剤を含有していてもよい。また微粒子を含有して光拡散性を示す粘着層などであってもよい。
【００９１】
光学フィルムの片面又は両面への粘着層の付設は、適宜な方式で行いうる。その例としては、例えばトルエンや酢酸エチル等の適宜な溶剤の単独物又は混合物からなる溶媒にベースポリマーまたはその組成物を溶解又は分散させた１０〜４０重量％程度の粘着剤溶液を調製し、それを流延方式や塗布方式等の適宜な展開方式で偏光板上または光学フィルム上に直接付設する方式、あるいは前記に準じセパレータ上に粘着層を形成してそれを偏光板上または光学フィルム上に移着する方式などがあげられる。
【００９２】
粘着層は、異なる組成又は種類等のものの重畳層として偏光板や光学フィルムの片面又は両面に設けることもできる。また両面に設ける場合に、偏光板や光学フィルムの表裏において異なる組成や種類や厚さ等の粘着層とすることもできる。粘着層の厚さは、使用目的や接着力などに応じて適宜に決定でき、一般には１〜５００μｍであり、５〜２００μｍが好ましく、特に１０〜１００μｍが好ましい。
【００９３】
粘着層の露出面に対しては、実用に供するまでの間、その汚染防止等を目的にセパレータが仮着されてカバーされる。これにより、通例の取扱状態で粘着層に接触することを防止できる。セパレータとしては、上記厚さ条件を除き、例えばプラスチックフィルム、ゴムシート、紙、布、不織布、ネット、発泡シートや金属箔、それらのラミネート体等の適宜な薄葉体を、必要に応じシリコーン系や長鏡アルキル系、フッ素系や硫化モリブデン等の適宜な剥離剤でコート処理したものなどの、従来に準じた適宜なものを用いうる。
【００９４】
なお本発明において、上記した偏光板を形成する偏光子や透明保護フィルムや光学フィルム等、また粘着層などの各層には、例えばサリチル酸エステル系化合物やべンゾフェノール系化合物、ベンゾトリアゾール系化合物やシアノアクリレート系化合物、ニッケル錯塩系化合物等の紫外線吸収剤で処理する方式などの方式により紫外線吸収能をもたせたものなどであってもよい。
【００９５】
本発明の光学フィルムは液晶表示装置等の各種装置の形成などに好ましく用いることができる。液晶表示装置の形成は、従来に準じて行いうる。すなわち液晶表示装置は一般に、液晶セルと光学フィルム、及び必要に応じての照明システム等の構成部品を適宜に組立てて駆動回路を組込むことなどにより形成されるが、本発明においては本発明による光学フィルムを用いる点を除いて特に限定はなく、従来に準じうる。液晶セルについても、例えばＴＮ型やＳＴＮ型、π型などの任意なタイプのものを用いうる。
【００９６】
液晶セルの片側又は両側に前記光学フィルムを配置した液晶表示装置や、照明システムにバックライトあるいは反射板を用いたものなどの適宜な液晶表示装置を形成することができる。その場合、本発明による光学フィルムは液晶セルの片側又は両側に設置することができる。両側に光学フィルムを設ける場合、それらは同じものであってもよいし、異なるものであってもよい。さらに、液晶表示装置の形成に際しては、例えば拡散板、アンチグレア層、反射防止膜、保護板、プリズムアレイ、レンズアレイシート、光拡散板、バックライトなどの適宜な部品を適宜な位置に１層又は２層以上配置することができる。
【００９７】
次いで有機エレクトロルミネセンス装置（有機ＥＬ表示装置）について説明する。一般に、有機ＥＬ表示装置は、透明基板上に透明電極と有機発光層と金属電極とを順に積層して発光体（有機エレクトロルミネセンス発光体）を形成している。ここで、有機発光層は、種々の有機薄膜の積層体であり、例えばトリフェニルアミン誘導体等からなる正孔注入層と、アントラセン等の蛍光性の有機固体からなる発光層との積層体や、あるいはこのような発光層とペリレン誘導体等からなる電子注入層の積層体や、またあるいはこれらの正孔注入層、発光層、および電子注入層の積層体等、種々の組み合わせをもった構成が知られている。
【００９８】
有機ＥＬ表示装置は、透明電極と金属電極とに電圧を印加することによって、有機発光層に正孔と電子とが注入され、これら正孔と電子との再結合によって生じるエネルギーが蛍光物資を励起し、励起された蛍光物質が基底状態に戻るときに光を放射する、という原理で発光する。途中の再結合というメカニズムは、一般のダイオードと同様であり、このことからも予想できるように、電流と発光強度は印加電圧に対して整流性を伴う強い非線形性を示す。
【００９９】
有機ＥＬ表示装置においては、有機発光層での発光を取り出すために、少なくとも一方の電極が透明でなくてはならず、通常酸化インジウムスズ（ＩＴＯ）などの透明導電体で形成した透明電極を陽極として用いている。一方、電子注入を容易にして発光効率を上げるには、陰極に仕事関数の小さな物質を用いることが重要で、通常Ｍｇ−Ａｇ、Ａｌ−Ｌｉなどの金属電極を用いている。
【０１００】
このような構成の有機ＥＬ表示装置において、有機発光層は、厚さ１０ｎｍ程度ときわめて薄い膜で形成されている。このため、有機発光層も透明電極と同様、光をほぼ完全に透過する。その結果、非発光時に透明基板の表面から入射し、透明電極と有機発光層とを透過して金属電極で反射した光が、再び透明基板の表面側へと出るため、外部から視認したとき、有機ＥＬ表示装置の表示面が鏡面のように見える。
【０１０１】
電圧の印加によって発光する有機発光層の表面側に透明電極を備えるとともに、有機発光層の裏面側に金属電極を備えてなる有機エレクトロルミネセンス発光体を含む有機ＥＬ表示装置において、透明電極の表面側に偏光板を設けるとともに、これら透明電極と偏光板との間に位相差板を設けることができる。
【０１０２】
位相差板および偏光板は、外部から入射して金属電極で反射してきた光を偏光する作用を有するため、その偏光作用によって金属電極の鏡面を外部から視認させないという効果がある。特に、位相差板を1 ／4 波長板で構成し、かつ偏光板と位相差板との偏光方向のなす角をπ／4 に調整すれば、金属電極の鏡面を完全に遮蔽することができる。
【０１０３】
すなわち、この有機ＥＬ表示装置に入射する外部光は、偏光板により直線偏光成分のみが透過する。この直線偏光は位相差板により一般に楕円偏光となるが、とくに位相差板が1 ／4 波長板でしかも偏光板と位相差板との偏光方向のなす角がπ／4 のときには円偏光となる。
【０１０４】
この円偏光は、透明基板、透明電極、有機薄膜を透過し、金属電極で反射して、再び有機薄膜、透明電極、透明基板を透過して、位相差板に再び直線偏光となる。そして、この直線偏光は、偏光板の偏光方向と直交しているので、偏光板を透過できない。その結果、金属電極の鏡面を完全に遮蔽することができる。
【０１０５】
【実施例】
以下、本発明を実施例等をあげて説明する。各例で用いた液晶ポリマーは、下記化４〜８に示す通りである。化式中、括弧外の数値はモル％であり、液晶ポリマーは便宜的にブロック体として表示している。液晶ポリマーの液晶温度範囲は、ホットプレート（加熱ステージ）付き偏光顕微鏡観察（（株）ニコン製，ＥＣＬＩＰＳＥ Ｅ６００ＰＯＬ）により測定した値である。液晶ポリマーのｇ：ガラス転移温度（℃）、ｎ：ネマティック液晶温度範囲、ｉ：等方相転移温度（℃）である。
【０１０６】
液晶ポリマー１：重量平均分子量８０００
【化４】

（ｇ ９０℃ ｎ ２８０℃ ｉ）
【０１０７】
液晶ポリマー２：重量平均分子量６０００
【化５】

（ｇ ９４℃ ｎ ２５５℃ ｉ）
【０１０８】
液晶ポリマー３：重量平均分子量６０００
【化６】

（ｇ ９６℃ ｎ ２１０℃ ｉ）
【０１０９】
液晶ポリマー４：重量平均分子量３５０００
【化７】

（ｇ ９６℃ ｎ ２９０℃ ｉ）
【０１１０】
液晶ポリマー５：重量平均分子量６０００
【化８】

（ｇ ９５℃ ｎ ２３０℃ ｉ）
【０１１１】
（表面自由エネルギー）
表面自由エネルギーの測定は、液晶ポリマーを液晶温度（１５０℃）にして、加熱ペンダントドロップ法によって、接触角計（協和界面科学（株）製）で測定した。
【０１１２】
（粘度）
粘度の測定は、液晶ポリマーを液晶温度（１５０℃）にして、ハーケ社製のレオメーター Ｒｈｅｏｗｉｎ Ｐｒｏによって測定した。
【０１１３】
実施例１
中心線平均粗さ（Ｒａ）が１５ｎｍの二軸延伸ポリエチレンテレフタレート（ＰＥＴ）フィルム上に、上記液晶ポリマー１をシクロペンタノンに溶解し濃度１５重量％に調整した溶液をバーコートにより塗布、１５０℃で２分間乾燥して、厚さ１．２μｍの液晶層を形成した液晶フィルムを作製した。
【０１１４】
一方、ガラス基板上にフォトマスクを利用して、微細加工を施したポリイミド配向膜（ラビング方向は部分的に異なるもの）を形成した。
【０１１５】
上記配向膜上に、液晶フィルムの液晶層側を、１５０℃の温度で熱ラミネーションした。その後、室温（２３℃）まで冷却した後、ＰＥＴフィルムを１８０°ピールしながら剥離し、液晶層をガラス基板上の配向膜に転写した。転写性は、凝集破壊なく転写できたか否かを目視および顕微鏡観察により以下の基準で確認した。○：良好。×：部分転写不良がある。結果を表１に示す。
【０１１６】
次いで、１５０℃で５分間加熱処理することで、微細加工された配向膜方向に液晶層を再配向させた。配向性は、偏光顕微鏡観察およびライトテーブル上において２枚の偏光板の間にサンプルを入れての目視観察により以下の基準で確認した。○：良好。×：配向しない。結果を表１に示す。
【０１１７】
上記加熱による再配向後に、室温（２３℃）まで冷却して、液晶配向層のネマチック構造を固定化した。その後、偏光顕微鏡を用いて、配向したガラス基板上の液晶配向層表面のはじき状態を目視観察した。○：ハジキなし、良好。×：数μｍのハジキが多数あり。結果を表１に示す。
【０１１８】
実施例２、３、比較例１、２、参考例１
実施例１において、液晶ポリマーの種類、ＰＥＴフィルムの中心線平均粗さ（Ｒａ）を表１に示すように変えたこと以外は実施例１と同様にして、液晶層をガラス基板上の配向膜に転写した。また、実施例１と同様にして、転写した液晶層を再配向させた後、固定化した。また、液晶層の転写性、配向性、得られた液晶配向層表面のはじき状態を目視観察した。結果を表１に示す。
【０１１９】
【表１】

表１より、本発明の液晶フィルムは、転写性、配向性が良好であり、歩留りよく液晶配向フィルムを製造できることが分かる。また基材フィルム（ＰＥＴフィルム）の表面粗さが２０ｎｍの場合には、得られる液晶配向層のはじき状態が良いことが分かる。
【図面の簡単な説明】
【図１】本発明の液晶配向フィルムの製造方法を示す、概念断面図である。
【符号の説明】
Ａ 液晶フィルム
１ 基材フィルム
２ 液晶層
２′液晶配向層
３ 他の基材（配向基材）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal film in which a liquid crystal layer is formed of a liquid crystal polymer. Moreover, this invention relates to the manufacturing method of the liquid crystal aligning film using the said liquid crystal film. The present invention also relates to a liquid crystal alignment film obtained by the production method and an optical film using at least one liquid crystal alignment film. The liquid crystal alignment film of this invention can be used as a phase difference plate. Moreover, the liquid crystal aligning film of this invention can be used as optical films, such as a viewing angle compensation film, an optical compensation film, an elliptically polarizing film, individually or in combination with another film. Furthermore, the present invention relates to an image display device such as a liquid crystal display device, an organic EL display device and a PDP using the optical film.
[0002]
[Prior art]
In recent years, a phase difference plate that controls the phase of light has become one of the important optical elements in the fields of optics and optoelectronics. Conventionally, a retardation plate is produced by uniaxially or biaxially stretching a polymer film. However, a retardation plate using a polymer film cannot satisfy sufficient optical characteristics. As a retardation plate, a liquid crystal alignment layer formed on an alignment film is known. The liquid crystal layer is obtained by a method of applying and curing a liquid crystal monomer on the alignment film, or a method of applying and drying a liquid crystal polymer (see Patent Document 1). In order to form the liquid crystal layer on the alignment film with a uniform thickness, generally, the liquid crystal material is generally applied by spin coating and then aligned. However, in the spin coating method, usually 90% or more of the expensive liquid crystal material (coating liquid) is scattered, so that the material yield of the liquid crystal material is poor and the cost becomes expensive.
[0003]
As the phase difference plate, a plate in which slow axes or fast axes in different directions are formed in a plurality of regions may be required. However, the retardation plate obtained by stretching and orientation of the polymer film is in the form of a film and has a uniform slow axis or fast axis in all regions within the film. Therefore, in a retardation plate obtained from a polymer film, it is very difficult to form a slow axis or a fast axis in different directions in a plurality of regions in a plane.
[0004]
In addition, a phase difference element having a plurality of phase difference regions with different slow axis directions or fast axis directions has been proposed (see Patent Document 2). The phase difference element is formed by patterning regions with different alignment axis directions in the liquid crystal layer by aligning the polymer layer that can be aligned with light by exposing it with polarized light and providing the liquid crystal layer in contact with the polymer layer. is doing. However, this method has a problem that when light is irradiated after the production of a polymer layer that can be aligned by light, the alignment of the polymer layer changes and the liquid crystal is not aligned in the target direction.
[0005]
In addition, a liquid crystal layer was formed on the alignment film by coating or the like and aligned by using a polyimide alignment film in which a region was formed using a photoresist and a rubbing process was performed in a different direction for each region. A phase difference element has been proposed (see Patent Document 3). However, in this method, when a solution in which a liquid crystal material is dissolved in a solvent is applied, the alignment film may change depending on the solvent, and there is a problem that the liquid crystal material is not aligned in the target direction. In addition, the adhesion between the liquid crystal alignment layer and the alignment film after aligning the liquid crystal layer is weak and easy to peel off.
[0006]
[Patent Document 1]
Japanese Patent No. 2784680
[Patent Document 2]
JP-A-6-289374
[Patent Document 3]
Japanese Patent No. 3360787
[0007]
[Problems to be solved by the invention]
The present invention provides a liquid crystal film in which a liquid crystal layer is formed of a liquid crystal polymer on a base film, and the liquid crystal alignment film can be produced with good yield by transferring and then aligning. With the goal.
[0008]
Moreover, it aims at providing the method of manufacturing a liquid crystal aligning film with a sufficient yield using the said liquid crystal film.
[0009]
Another object of the present invention is to provide a method for producing a liquid crystal alignment film having a plurality of retardation regions having different slow axis directions or fast axis directions with high yield.
[0010]
Furthermore, it aims at providing the liquid crystal aligning film obtained by the said manufacturing method, the optical film using the said liquid crystal aligning film, and the image display apparatus using the said optical film.
[0011]
[Means for Solving the Problems]
As a result of intensive research aimed at achieving the above object, the present inventors have found that the above problems can be solved by the following method for producing a liquid crystal alignment film, and have completed the present invention.
[0012]
  That is, the present invention is a liquid crystal film in which a liquid crystal layer (2) is formed of a liquid crystal polymer on a base film (1), and the liquid crystal layer (2) It can be bonded to the alignment substrate (3), and after bonding, only the substrate film (1) can be peeled off and transferred to the alignment substrate (3). The liquid crystal layer (2) transferred to the material (3) uses a liquid crystal film that can be aligned at a temperature exhibiting liquid crystallinity,
  A step of thermally laminating the liquid crystal layer (2) to the alignment substrate (3) at a temperature equal to or higher than the glass transition point of the liquid crystal polymer forming the liquid crystal layer (2);
After cooling below the glass transition point of the liquid crystal polymer, peeling the substrate film (1) and transferring the liquid crystal layer (2) to the alignment substrate (3);
Reheating to a temperature above the glass transition point of the liquid crystal polymer to align the liquid crystal layer (2) on the alignment substrate (3) to form a liquid crystal alignment layer (2 ');
Cooling to a temperature below the glass transition point of the liquid crystal polymer to fix the alignment of the liquid crystal alignment layer (2 ′).And
The liquid crystal polymer has a viscosity of 500 to 50000 [P] at a temperature exhibiting liquid crystallinity.The present invention relates to a method for producing a liquid crystal alignment film.
[0013]
The liquid crystal layer (2) of the liquid crystal film (A) of the present invention has good transferability to another substrate (3). In addition, since the liquid crystal layer (2) is formed in advance on the base film (1), the base (3) is not attacked by the solvent and can be transferred without changing the performance of the base (3). is there. Further, the liquid crystal layer (2) can be aligned after transfer to the substrate (3). If such a liquid crystal film (A) is used, the liquid crystal alignment film can be produced with high yield by orienting the liquid crystal layer (2) after being transferred to the substrate (3).
[0014]
In the liquid crystal film (A), the liquid crystal polymer preferably has a viscosity of 500 to 50000 [P] at a temperature exhibiting liquid crystallinity. In order to bond the other base material (3) so as not to sandwich the bubbles, it is preferable to use a liquid crystal polymer having a viscosity in the liquid crystal temperature range within the above range. If the viscosity is higher than this, bubbles easily enter, and if the viscosity is too low, a thickness change is likely to occur during bonding. The viscosity is more preferably 1000 to 20000 [P].
[0015]
In the liquid crystal film (A), the liquid crystal polymer preferably has a surface free energy of 400 μN / cm or less at a temperature exhibiting liquid crystallinity. In order for the liquid crystal layer (2) transferred to the other substrate (3) to have no appearance defects such as repellency during subsequent orientation, the surface free energy in the liquid crystal temperature range of the liquid crystal polymer is 400 μN / cm or less. Some are suitable. The surface free energy is more preferably 300 μN / cm or less. Moreover, when the surface free energy of the liquid crystal polymer is in the above range, the adhesion between the liquid crystal layer (2) and the other substrate (3) is good.
[0016]
In the liquid crystal film (A), the liquid crystal layer (2) is preferably formed by applying and drying a liquid crystal polymer on the base film (1). The method for forming the liquid crystal layer (2) is not particularly limited, and the liquid crystal layer (2) can be obtained by a method of applying and curing a liquid crystal monomer to the base film (1) or a method of applying and drying a liquid crystal polymer. From the point that it can be bonded to another substrate (3) at a temperature showing liquid crystallinity, it is preferably formed by applying and drying a liquid crystal polymer. In addition, even what apply | coated and hardened | cured the liquid crystal monomer can be preferably used if it has a temperature range which shows liquid crystallinity after hardening.
[0017]
In the liquid crystal film (A), it is preferable that the base film (1) is an alignment base and the liquid crystal polymer forming the liquid crystal layer (2) is aligned. Orienting the liquid crystal polymer that forms the liquid crystal layer (2) is preferable from the viewpoint of easy reorientation after being bonded to another substrate (3).
[0018]
In the liquid crystal film (A), the base film (1) is preferably a biaxially stretched polyethylene terephthalate film. The base film (1) on which the liquid crystal layer (2) is provided is preferably excellent in heat resistance because thermal lamination is performed at or above the glass transition point of the liquid crystal polymer forming the liquid crystal layer (2). In view of cost, a biaxially stretched polyethylene terephthalate film is most suitable.
[0019]
In the liquid crystal film (A), the center line average roughness (Ra) of the surface of the base film (1) on the side on which the liquid crystal layer (2) is formed is preferably 20 nm or less. When the substrate film (1) having a center line average roughness (Ra) larger than 20 nm is used, the liquid crystal orientation obtained by reheating the liquid crystal layer (2) transferred to the substrate (3) It is not preferable because appearance defects such as repellency are likely to occur on the surface of the layer (2 ′). The center line average roughness (Ra) is more preferably 15 nm or less.
[0020]
The centerline average roughness (Ra) was measured according to JIS B0601, using Surfcom 470A manufactured by Tokyo Seimitsu Co., Ltd. as a stylus type surface roughness measuring machine. The measurement is performed by scanning the uneven surface with a length of 3 mm in a fixed direction through a measuring needle having a diameter of 1 mm with a tip portion made of diamond having a conical shape with an apex angle of 55 degrees. This was calculated by measuring the change in movement of the surface roughness and recording it from the recorded surface roughness curve.
[0021]
In the liquid crystal film (A), the other substrate (3) is preferably an alignment substrate. If the other substrate (3) is an alignment substrate, the liquid crystal layer (2) can be aligned by heating the liquid crystal layer (2) after transfer to form the liquid crystal alignment layer (2 ').
[0023]
  Of the present inventionThe method for producing the liquid crystal alignment film is as shown in the conceptual diagram of FIG. 1, and the liquid crystal material is not formed on the alignment substrate by spin coating or the like, but on the substrate film (1). The liquid crystal layer (2) is transferred to the alignment substrate (3) by thermally laminating the liquid crystal layer (2) provided in advance, and then the liquid crystal layer (2) is reheated to realign the liquid crystal alignment layer (2 ′ ) Is formed. Thus, since the liquid crystal layer (2) previously formed on the base film (1) is transferred onto the alignment base (3), the yield of the liquid crystal material is higher than that of a coating method such as a spin coat method. Very good. According to the production method of the present invention, the liquid crystal alignment layer (2 ′) can be formed on the large alignment substrate (3). Furthermore, in the production method of the present invention, forming the liquid crystal layer (2) on the base film (1), and employing a coating with less use loss of a coating liquid such as a gravure coating method or a die coating method, By the roll-to-roll method, thermal lamination can be continuously performed on the alignment substrate (3), and the cost reduction effect in terms of productivity is also great.
[0024]
In the production method of the present invention, since the liquid crystal layer (2) previously formed on the base film (1) is transferred onto the orientation base (3), the orientation base (3) is made of a solvent. Not attacked. Therefore, the performance of the alignment substrate (3) does not change. If a polyimide alignment film that has been rubbed in different directions for each region is used as the alignment substrate (3), the liquid crystal layer can be aligned in the target direction, and the slow axis direction or the fast axis direction is different. A liquid crystal alignment film (retardation plate) having the above retardation region can be produced.
[0025]
In the method for producing a liquid crystal alignment film, the alignment substrate (3) having a plurality of regions having different alignment directions can be used. By using such an alignment substrate (3), a liquid crystal alignment film having a plurality of retardation regions having different slow axis directions or fast axis directions can be obtained.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the liquid crystal film (A) of the liquid crystal layer (2) formed of the liquid crystal polymer on the base film (1) is used.
[0028]
The liquid crystal layer (2) can be formed, for example, by applying a liquid crystal polymer on the substrate film (1) and drying. As the liquid crystal polymer, polymers having various skeletons of main chain type, side chain type, or a composite type thereof exhibiting nematic, cholesteric or smectic properties can be used without particular limitation. As the liquid crystal polymer, a liquid crystal polymer that is nematically aligned in a liquid crystal state and is in a glass state below the liquid crystal transition point is preferable. The liquid crystal polymer is capable of forming the liquid crystal layer (2) on the base film (1), transferable to another base material (3), and further alignable thereafter. .
[0029]
Examples of the main chain type liquid crystal polymer include condensation polymers having a structure in which mesogenic groups composed of aromatic units and the like are bonded, for example, polymers such as polyester, polyamide, polycarbonate, and polyesterimide. Examples of the aromatic unit that becomes a mesogenic group include phenyl, biphenyl, and naphthalene types, and these aromatic units have substituents such as a cyano group, an alkyl group, an alkoxy group, and a halogen group. May be.
[0030]
Examples of the side chain type liquid crystal polymer include those having a polyacrylate-based, polymethacrylate-based, polysiloxane-based, or polymalonate-based main chain as a skeleton, and a mesogenic group composed of a cyclic unit or the like in the side chain. Examples of the cyclic unit serving as a mesogenic group include biphenyl, phenylbenzoate, phenylcyclohexane, azoxybenzene, azomethine, azobenzene, phenylpyrimidine, diphenylacetylene, diphenylbenzoate, and bicyclohexane. Cyclohexylbenzene, terphenyl and the like. In addition, the terminal of these cyclic units may have substituents, such as a cyano group, an alkyl group, an alkoxy group, a halogen group, for example.
[0031]
Further, the mesogenic group of any liquid crystal polymer may be bonded via a spacer portion that imparts flexibility. Examples of the spacer part include a polymethylene chain and a polyoxymethylene chain. The number of repeating structural units forming the spacer portion is appropriately determined depending on the chemical structure of the mesogenic portion, but the repeating unit of the polymethylene chain is 0 to 20, preferably 2 to 12, and the repeating unit of the polyoxymethylene chain is 0 to 0. 10, preferably 1-3.
[0032]
A cholesteric liquid crystal polymer can be used by adding a low molecular chiral agent to a liquid crystal polymer exhibiting nematic liquid crystal alignment or introducing a chiral component into the polymer component.
[0033]
The molecular weight of the liquid crystal polymer is not particularly limited, but preferably has a weight average molecular weight of about 2,000 to 100,000. When the weight average molecular weight of the liquid crystal polymer is increased, the weight average molecular weight of the liquid crystal polymer is more preferably 50,000 or less from the orientation as the liquid crystal. Moreover, since there exists a tendency for the film formability as a non-fluidized layer to become scarce when the weight average molecular weight of a liquid crystal polymer becomes small, it is more preferable that the weight average molecular weight of a liquid crystal polymer shall be 2.5000 or more.
[0034]
The liquid crystal polymer is preferably a polyacrylate type or polymethacrylate type side chain type liquid crystal polymer. Of these, polyacrylates are preferred.
[0035]
As a specific example, for example, as the monomer unit (a), for example, the general formula (a):
[Chemical 1]

(However, R¹ Is a hydrogen atom or a methyl group, a is a positive integer of 1-6, X¹ Is -CO₂ -Group or -OCO- group is R² Represents a cyano group, an alkoxy group, a fluoro group or an alkyl group, and b and c each represents an integer of 1 or 2. And a monomer unit represented by formula (1).
[0036]
Moreover, what has a monomer unit represented by the monomer unit represented by the said general formula (a) and the following general formula (b) is mention | raise | lifted. Examples of the monomer unit (b) include the general formula (b):
[Chemical 2]

(However, R^Three Is a hydrogen atom or a methyl group, X² Is -CO₂ A-group or -OCO- group, -O- or a single bond, R^Four Is the general formula (c):
[Chemical 3]

The substituent represented by these is shown. R^Five Is a monomer unit represented by a cyano group, an alkoxy group, a fluoro group, or an alkyl group.
[0037]
Further, the ratio of the monomer unit (a) to the monomer unit (b) is not particularly limited and varies depending on the type of the monomer unit, but in terms of molar ratio, (b) / {(a) + (b )} <0.8. Furthermore, (b) / {(a) + (b)} = 0 to 0.75, and further preferably 0.2 to 0.7.
[0038]
The liquid crystal layer (2) can be formed of a liquid crystal polymer obtained by applying and curing a liquid crystal monomer on the substrate film (1). As the liquid crystal monomer, one that becomes a liquid crystal polymer exhibiting nematic, cholesteric or smectic liquid crystal alignment after polymerization is appropriately selected and used. Generally, the liquid crystal monomer has various skeletons exhibiting the same liquid crystal alignment as described above, and has at least one polymerizable functional group such as an unsaturated double bond such as an acryloyl group, a methacryloyl group, or a vinyl group or an epoxy group at the terminal. Liquid crystal compound. In order to improve the durability of the liquid crystal layer (2), a liquid crystal monomer having two or more polymerizable functional groups can be used and crosslinked together with polymerization. In addition, as a liquid crystal monomer, what shows nematic orientation after superposition | polymerization is preferable.
[0039]
The liquid crystal monomer usually contains a polymerization initiator. The polymerization initiator is appropriately selected according to the polymerization method of the liquid crystal monomer. Examples of the polymerization method of the liquid crystal monomer include ultraviolet polymerization, and in this case, a photopolymerization initiator is used. Examples of the photopolymerization initiator include Irgacure 907, 184, 651, and 369 manufactured by Ciba Specialty Chemicals. The addition amount of the photopolymerization initiator is added to such an extent that the orientation is not disturbed in consideration of the type of polymerizable liquid crystal monomer and the like. Usually, about 0.5-30 weight part is preferable with respect to 100 weight part of polymeric liquid crystal monomers. Particularly preferred is 3 parts by weight or more.
[0040]
As the substrate film (1), a transparent substrate capable of forming the liquid crystal layer (2) can be used without particular limitation. For example, various types of single-layer or multi-layer plastic films, glass plates and metals can be used. Examples of the plastic film include films made of transparent polymers such as polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, polycarbonate polymers, and acrylic polymers such as polymethyl methacrylate. Is given. Styrene polymers such as polystyrene and acrylonitrile / styrene copolymers, polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, olefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, nylon and aromatic polyamides, etc. Examples thereof include films made of transparent polymers such as amide polymers. Furthermore, imide polymers, sulfone polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers Examples thereof include a film made of a transparent polymer such as a polymer, an epoxy-based polymer, and a blend of the aforementioned polymers.
[0041]
Moreover, a base film (1) can be made into an orientation base material. Various conventionally known substrates can be used as the alignment substrate. For example, a thin alignment film made of polyimide, polyvinyl alcohol, or the like is formed on the transparent substrate and then rubbed, a stretched film obtained by stretching the transparent substrate, a cinnamate skeleton or an azobenzene skeleton. A polymer or polyimide having irradiated with polarized ultraviolet rays can be used. When the base film (1) is an oriented base material, it is preferable to use a stretched film obtained by stretching a transparent base material. A biaxially stretched polyethylene terephthalate film is particularly preferable.
[0042]
The method for forming the liquid crystal layer (2) is not particularly limited. For the application of the liquid crystal monomer and the liquid crystal polymer, either a solution application using a solution obtained by dissolving them in a solvent or a melt application method can be employed.
[0043]
The solvent used in preparing the liquid crystal polymer and liquid crystal monomer solution varies depending on the type of liquid crystal polymer, liquid crystal monomer, and the like, and is appropriately determined. For example, usually, halogenated hydrocarbons such as chloroform, dichloromethane, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, phenols such as phenol and parachlorophenol, benzene, toluene, xylene, methoxybenzene, 1,2-di Aromatic hydrocarbons such as methoxybenzene, acetone, ethyl acetate, tert-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, ethyl cellosolve, butyl cellosolve, 2-pyrrolidone N-methyl-2-pyrrolidone, pyridine, triethylamine, tetrahydrofuran, dimethylformamide, dimethylacetate Amides, dimethyl sulfoxide, acetonitrile, butyronitrile, carbon disulfide, cyclohexanone or the like can be used. The concentration of the solution depends on the solubility of the liquid crystal polymer, liquid crystal monomer, etc. and the film thickness of the liquid crystal layer (2), and can be determined as appropriate. Usually, it is in the range of 3 to 50% by weight, preferably 7 to 30% by weight.
[0044]
For example, a roll coating method, a gravure coating method, or a bar coating method is preferably employed as a method for applying the solution adjusted to a desired concentration using the solvent. After application, the solvent is removed to form the liquid crystal layer (2). The conditions for removing the solvent are not particularly limited, and it is sufficient that the solvent can be generally removed and the liquid crystal layer does not flow or even flow down. Usually, the solvent is removed by drying at room temperature, drying in a drying furnace, heating on a hot plate, or the like.
[0045]
When aligning the liquid crystal layer (2), it is performed by heat treatment at a temperature at which the liquid crystal polymer or liquid crystal monomer exhibits a liquid crystal state. The said heat processing temperature is suitably adjusted with a liquid crystal polymer or a liquid crystal monomer. The heat treatment can be performed by the same method as the above drying method. The heat treatment time varies depending on the heat treatment temperature and the liquid crystal polymer or liquid crystal monomer, and cannot be generally specified, but is usually selected in the range of 10 seconds to 2 hours, preferably 20 seconds to 30 minutes.
[0046]
In the case where the liquid crystal layer (2) is formed from a liquid crystal monomer, various means can be adopted as the polymerization method depending on the type of the liquid crystal monomer. For example, a photopolymerization method by light irradiation can be adopted. Light irradiation is performed by, for example, ultraviolet irradiation. The ultraviolet irradiation conditions are preferably in an inert gas atmosphere in order to sufficiently promote the reaction. A high-pressure mercury ultraviolet lamp is typically used. Different types of lamps such as metahalide UV lamps and incandescent tubes can also be used. It should be noted that the liquid crystal layer surface temperature at the time of ultraviolet irradiation is appropriately adjusted by, for example, a cold mirror, water cooling or other cooling treatment, or by increasing the line speed.
[0047]
The thickness of the liquid crystal layer (2) is not particularly limited, but is usually adjusted in the range of about 1 to 20 μm, more preferably 2 to 10 μm. The liquid crystal layer (2) can be formed as a single layer or can be formed as a multilayer.
[0048]
As described above, a liquid crystal film (A) in which a liquid crystal layer (2) is provided on a base film (1) is prepared. The liquid crystal layer (2) of the liquid crystal film (A) can be transferred to another substrate. The other substrate can be appropriately determined according to the use, but the oriented substrate (3) is preferred.
[0049]
The alignment substrate (3) is not particularly limited, and those conventionally used can be used without particular limitation. For example, the thing similar to what was demonstrated when using a base film (1) as an orientation base material is mention | raise | lifted. As the alignment substrate (3), a thin layer alignment film made of polyimide, polyvinyl alcohol or the like is formed on the transparent substrate and then rubbed, a polymer having a cinnamate skeleton or an azobenzene skeleton, It is preferable to use a polyimide irradiated with polarized ultraviolet rays. In addition, formation of the area | region of 2 directions from which the orientation direction differs to an orientation base material (3) can be formed with a polyimide etc. using a photomask etc. for transparent base materials, such as a glass substrate.
[0050]
The liquid crystal film (A) that can be transferred to the alignment substrate (3) is used for the production of a liquid crystal alignment film. First, the liquid crystal layer (2) of the liquid crystal film (A) is thermally laminated on the alignment substrate (3).
[0051]
Thermal lamination is performed at a temperature equal to or higher than the glass transition point of the liquid crystal polymer forming the liquid crystal layer (2). Usually, it is about +20 to + 150 ° C. and further +30 to + 120 ° C. than the glass transition point of the liquid crystal polymer. In addition, as thermal lamination, the method of heating the laminate roll itself, the method of heating what is bonded just before lamination, etc. are employable.
[0052]
Subsequently, after cooling to below the glass transition point of the said liquid crystal polymer, a base film (1) is peeled. Cooling is preferably performed until the temperature becomes about −10 to −150 ° C., and further −20 to −100 ° C., rather than the glass transition point. Cooling can be performed by leaving it in an atmosphere below the glass transition point. Also, forced cooling such as air cooling or water cooling can be performed. The liquid crystal layer (2) is transferred to the alignment substrate (3) by peeling off the substrate film (1).
[0053]
Next, reheating is performed to a temperature equal to or higher than the glass transition point of the liquid crystal polymer, and the liquid crystal layer (2) is aligned on the alignment substrate (3) to form a liquid crystal alignment layer (2 ').
[0054]
In addition, since the cost increases when the reheating temperature becomes high, and there are some having an isotropic phase when the reheating temperature becomes too high, the reheating is performed in a range where the liquid crystal polymer does not become the isotropic phase. The reheating is usually about +20 to + 150 ° C. and further +30 to + 120 ° C. than the glass transition point. The reheating time is preferably about 1 to 600 seconds, more preferably about 10 to 300 seconds.
[0055]
Subsequently, it cools to the temperature below the glass transition point of the said liquid crystal polymer, and fixes the orientation of a liquid crystal aligning layer (2 '). In the case of a nematic liquid crystal polymer, the nematic structure is fixed. In this way, a liquid crystal alignment film having the liquid crystal alignment layer (2 ′) with the alignment fixed on the alignment substrate (3) is obtained.
[0056]
The liquid crystal alignment film can be used together with the alignment substrate (3), and can be peeled from the alignment substrate (3) and used as an optical film. Furthermore, it can be transferred to another optical film for use. The liquid crystal alignment film can be used as an optical film such as a retardation plate, a viewing angle compensation film, an optical compensation film, and an elliptically polarizing film alone or in combination with other films. These will be described below.
[0057]
A polarizing plate is used for an optical film applied to an image display device such as a liquid crystal display device. The polarizing plate usually has a protective film on one side or both sides of the polarizer. The polarizer is not particularly limited, and various types can be used. Examples of the polarizer include hydrophilic polymer films such as polyvinyl alcohol film, partially formalized polyvinyl alcohol film, and ethylene / vinyl acetate copolymer partially saponified film, and two colors such as iodine and dichroic dye. And polyene-based oriented films such as those obtained by adsorbing a volatile substance and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, those obtained by stretching a polyvinyl alcohol film and adsorbing and orienting a dichroic material (iodine, dye) are preferably used. The thickness of the polarizer is not particularly limited, but is generally about 5 to 80 μm.
[0058]
A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution of boric acid or potassium iodide. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface and anti-blocking agent by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven dyeing by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.
[0059]
The protective film provided on one side or both sides of the polarizer preferably has excellent transparency, mechanical strength, thermal stability, moisture shielding properties, isotropic properties, and the like. Examples of the material for the protective film include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, polystyrene, acrylonitrile / styrene copolymers, and the like. Examples thereof include styrene polymers such as (AS resin) and polycarbonate polymers. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Examples of polymers that form protective films include polymer blends. Other examples include films made of thermosetting or ultraviolet curable resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone.
[0060]
Moreover, the polymer film described in JP-A-2001-343529 (WO01 / 37007), for example, (A) a thermoplastic resin having a substituted and / or unsubstituted imide group in the side chain, and (B) a substitution in the side chain And / or a resin composition containing an unsubstituted phenyl and a thermoplastic resin having a nitrile group. A specific example is a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used.
[0061]
A protective film that can be particularly preferably used in terms of polarization characteristics and durability is a triacetylcellulose film whose surface is saponified with an alkali or the like. The thickness of the transparent protective layer is arbitrary, but is generally 500 μm or less, more preferably 1 to 300 μm, and particularly preferably 5 to 300 μm for the purpose of reducing the thickness of the polarizing plate. In addition, when providing a protective film on both sides of a polarizer, the transparent protective film which consists of a polymer etc. which is different in the front and back can be used.
[0062]
Moreover, it is preferable that a transparent protective film has as little color as possible. Therefore, Rth = [(nx + ny) / 2−nz] · d (where nx and ny are the main refractive index in the plane of the film, nz is the refractive index in the film thickness direction, and d is the film thickness). A protective film having a retardation value in the film thickness direction of −90 nm to +75 nm is preferably used. By using a film having a thickness direction retardation value (Rth) of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the protective film can be almost eliminated. The thickness direction retardation value (Rth) is more preferably −80 nm to +60 nm, and particularly preferably −70 nm to +45 nm.
[0063]
The polarizer and the protective film are usually in close contact with each other through an aqueous adhesive or the like. Examples of aqueous adhesives include polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, aqueous polyurethanes, aqueous polyesters, and the like.
[0064]
As the protective film, a hard coat layer, an antireflection treatment, an anti-sticking treatment, or a treatment subjected to diffusion or anti-glare treatment can be used.
[0065]
Hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizing plate. For example, a cured film having excellent hardness and slipping properties with an appropriate ultraviolet curable resin such as acrylic or silicone is applied to the protective film. It can be formed by a method of adding to the surface. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art. Further, the anti-sticking treatment is performed for the purpose of preventing adhesion with an adjacent layer.
[0066]
The anti-glare treatment is applied for the purpose of preventing the outside light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by a sandblasting method or an embossing method. It can be formed by imparting a fine concavo-convex structure to the surface of the protective film by an appropriate method such as a blending method of transparent fine particles. The fine particles to be included in the formation of the surface fine concavo-convex structure are, for example, conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide or the like having an average particle size of 0.5 to 50 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used. When forming a surface fine uneven structure, the amount of fine particles used is generally about 2 to 50 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.
[0067]
The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the protective film itself, or can be provided separately from the transparent protective layer as an optical layer.
[0068]
The polarizing plate can be used as an elliptically polarizing plate or a circularly polarizing plate on which retardation plates are laminated. The elliptically polarizing plate or the circularly polarizing plate will be described. These change the linearly polarized light into elliptically polarized light or circularly polarized light, change the elliptically polarized light or circularly polarized light into linearly polarized light, or change the polarization direction of the linearly polarized light. In particular, a so-called quarter wave plate (also referred to as a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A 1/2 wavelength plate (also referred to as a λ / 2 plate) is usually used when changing the polarization direction of linearly polarized light.
[0069]
The elliptically polarizing plate is effectively used for black and white display without the above color by compensating (preventing) the coloration (blue or yellow) generated by the birefringence of the liquid crystal layer of the super twist nematic (STN) type liquid crystal display device. It is done. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed from an oblique direction. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which an image is displayed in color, and also has an antireflection function.
[0070]
As the phase difference plate, for example, various wavelength plates or those for the purpose of compensating for coloring or viewing angle due to birefringence of the liquid crystal layer can be used, and two types having an appropriate phase difference according to the purpose of use. Optical properties such as retardation can be controlled by laminating the above retardation plates. As the retardation plate, a birefringent film formed by stretching a film made of an appropriate polymer such as polycarbonate, norbornene resin, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene, other polyolefins, polyarylate, polyamide, Examples thereof include an alignment film made of a liquid crystal material such as a liquid crystal polymer, and an alignment layer of the liquid crystal material supported by the film.
[0071]
Moreover, it is laminated | stacked on a polarizing plate as a viewing angle compensation film, and is used as a wide viewing angle polarizing plate. The viewing angle compensation film is a film for widening the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than perpendicular to the screen.
[0072]
As such a viewing angle compensation retardation plate, a birefringent film that has been biaxially stretched or stretched in two orthogonal directions, a bidirectionally stretched film such as a tilted orientation film, and the like are used. Examples of the inclined alignment film include a film obtained by bonding a heat shrink film to a polymer film and stretching or / and shrinking the polymer film under the action of the contraction force by heating, and a film obtained by obliquely aligning a liquid crystal polymer. Can be mentioned. The viewing angle compensation film can be appropriately combined for the purpose of preventing coloring or the like due to a change in viewing angle based on a phase difference caused by a liquid crystal cell or increasing the viewing angle for good viewing.
[0073]
Also, from the viewpoint of achieving a wide viewing angle with good visibility, an optically compensated phase difference in which a liquid crystal polymer alignment layer, in particular an optically anisotropic layer composed of a discotic liquid crystal polymer gradient alignment layer, is supported by a triacetylcellulose film. A plate can be preferably used.
[0074]
In addition to the above, the optical layer laminated in practical use is not particularly limited. For example, one or more optical layers that may be used for forming a liquid crystal display device such as a reflective plate or a transflective plate are used. Can do. In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which an elliptical polarizing plate or a circular polarizing plate is further laminated with a reflecting plate or a semi-transmissive reflecting plate, or a polarizing plate in which a brightness enhancement film is further laminated on the polarizing plate. Can be given.
[0075]
A reflective polarizing plate is a polarizing plate provided with a reflective layer, and is used to form a liquid crystal display device or the like that reflects incident light from the viewing side (display side). Such a light source can be omitted, and the liquid crystal display device can be easily thinned. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is attached to one surface of the polarizing plate via a transparent protective layer or the like as necessary.
[0076]
Specific examples of the reflective polarizing plate include those in which a reflective layer is formed by attaching a foil or vapor-deposited film made of a reflective metal such as aluminum on one surface of a protective film matted as necessary. In addition, the protective film may contain fine particles to form a surface fine concavo-convex structure and a reflective layer having a fine concavo-convex structure thereon. The reflective layer having the fine concavo-convex structure has an advantage that incident light is diffused by irregular reflection to prevent directivity and glaring appearance and to suppress unevenness in brightness and darkness. Moreover, the protective film containing fine particles also has an advantage that incident light and its reflected light are diffused when passing through it and light and dark unevenness can be further suppressed. The reflective layer with a fine concavo-convex structure reflecting the surface fine concavo-convex structure of the protective film is transparently protected by an appropriate method such as a vapor deposition method such as a vacuum deposition method, an ion plating method, a sputtering method, or a plating method. It can be performed by a method of attaching directly to the surface of the layer.
[0077]
The reflective plate can be used as a reflective sheet in which a reflective layer is provided on an appropriate film according to the transparent film, instead of the method of directly imparting to the protective film of the polarizing plate. Since the reflective layer is usually made of metal, the usage form in which the reflective surface is covered with a protective film, a polarizing plate or the like is used to prevent a decrease in reflectance due to oxidation, and thus the long-term sustainability of the initial reflectance. More preferable is the point of avoiding the additional attachment of the protective layer.
[0078]
The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror that reflects and transmits light with the reflective layer. A transflective polarizing plate is usually provided on the back side of a liquid crystal cell, and displays an image by reflecting incident light from the viewing side (display side) when a liquid crystal display device is used in a relatively bright atmosphere. In a relatively dark atmosphere, a liquid crystal display device or the like that displays an image using a built-in light source such as a backlight built in the back side of the transflective polarizing plate can be formed. In other words, the transflective polarizing plate is useful for forming a liquid crystal display device of a type that can save energy of using a light source such as a backlight in a bright atmosphere and can be used with a built-in light source even in a relatively dark atmosphere. It is.
[0079]
A polarizing plate obtained by bonding a polarizing plate and a brightness enhancement film is usually provided on the back side of a liquid crystal cell. The brightness enhancement film reflects a linearly polarized light with a predetermined polarization axis or a circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device or reflection from the back side, and transmits other light. In addition, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting the light other than the predetermined polarization state. The The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for liquid crystal display image display or the like by supplying polarized light that is difficult to be absorbed by the polarizer. That is, when light is incident through the polarizer from the back side of the liquid crystal cell without using a brightness enhancement film, light having a polarization direction that does not coincide with the polarization axis of the polarizer is almost polarized. It is absorbed by the polarizer and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, approximately 50% of the light is absorbed by the polarizer, and the amount of light that can be used for liquid crystal image display or the like is reduced accordingly, resulting in a dark image. The brightness enhancement film allows light having a polarization direction that is absorbed by the polarizer to be reflected once by the brightness enhancement film without being incident on the polarizer, and further inverted through a reflective layer provided on the rear side thereof. Repeatedly re-enter the brightness enhancement film, and the brightness enhancement film transmits only polarized light whose polarization direction is such that the polarization direction of light reflected and inverted between the two can pass through the polarizer. Therefore, light such as a backlight can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.
[0080]
A diffusion plate may be provided between the brightness enhancement film and the reflective layer. The polarized light reflected by the brightness enhancement film is directed to the reflective layer or the like, but the installed diffuser plate uniformly diffuses the light passing therethrough and simultaneously cancels the polarized state and becomes a non-polarized state. That is, the diffuser plate returns the polarized light to the original natural light state. The light in the non-polarized state, that is, the natural light state is directed toward the reflection layer and the like, reflected through the reflection layer and the like, and again passes through the diffusion plate and reenters the brightness enhancement film. Thus, while maintaining the brightness of the display screen by providing a diffuser plate that returns polarized light to the original natural light state between the brightness enhancement film and the reflective layer, etc., the brightness unevenness of the display screen is reduced at the same time, A uniform and bright screen can be provided. By providing such a diffuser plate, it is considered that the first incident light has a moderate increase in the number of repetitions of reflection, and in combination with the diffusion function of the diffuser plate, a uniform bright display screen can be provided.
[0081]
The brightness enhancement film has a characteristic of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer thin film of dielectric material or a multilayer laminate of thin film films having different refractive index anisotropy. Such as a cholesteric liquid crystal polymer alignment film or a film substrate whose alignment liquid crystal layer is supported on a film substrate, reflecting either left-handed or right-handed circularly polarized light and transmitting other light Appropriate things such as can be used.
[0082]
Therefore, in the brightness enhancement film of the type that transmits linearly polarized light having the predetermined polarization axis as described above, the transmitted light is incident on the polarizing plate with the polarization axis aligned as it is, thereby efficiently transmitting while suppressing absorption loss due to the polarizing plate. Can be made. On the other hand, in a brightness enhancement film of a type that transmits circularly polarized light such as a cholesteric liquid crystal layer, it can be directly incident on a polarizer, but from the point of suppressing absorption loss, the circularly polarized light is linearly polarized through a retardation plate. It is preferable to make it enter into a polarizing plate. Note that circularly polarized light can be converted to linearly polarized light by using a quarter wave plate as the retardation plate.
[0083]
A retardation plate that functions as a quarter-wave plate in a wide wavelength range such as a visible light region exhibits, for example, a retardation layer that functions as a quarter-wave plate for light-color light having a wavelength of 550 nm and other retardation characteristics. It can be obtained by a method of superposing a retardation layer, for example, a retardation layer functioning as a half-wave plate. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one or more retardation layers.
[0084]
In addition, the cholesteric liquid crystal layer can also be obtained by reflecting circularly polarized light in a wide wavelength range such as a visible light region by combining two or more layers having different reflection wavelengths and having an overlapping structure. Based on this, transmitted circularly polarized light in a wide wavelength range can be obtained.
[0085]
Further, the polarizing plate may be formed by laminating a polarizing plate and two or three or more optical layers like the above-described polarization separation type polarizing plate. Therefore, a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above-mentioned reflective polarizing plate or transflective polarizing plate and a retardation plate are combined may be used.
[0086]
The elliptically polarizing plate and the reflective elliptical polarizing plate are obtained by laminating a polarizing plate or a reflective polarizing plate and a retardation plate in an appropriate combination. Such an elliptical polarizing plate can be formed by sequentially laminating them in the manufacturing process of the liquid crystal display device so as to be a combination of a (reflective) polarizing plate and a retardation plate. An optical film such as an elliptically polarizing plate is advantageous in that it can improve the production efficiency of a liquid crystal display device and the like because of excellent quality stability and lamination workability.
[0087]
The optical film of the present invention can be provided with an adhesive layer. The pressure-sensitive adhesive layer can be used for adhering to a liquid crystal cell and also used for laminating optical layers. When adhering the optical films, their optical axes can be set at an appropriate arrangement angle in accordance with the target retardation characteristics.
[0088]
The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is appropriately selected. Can be used. In particular, those having excellent optical transparency such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and being excellent in weather resistance, heat resistance and the like can be preferably used.
[0089]
In addition to the above, in terms of prevention of foaming and peeling phenomena due to moisture absorption, deterioration of optical properties and liquid crystal cell warpage due to differences in thermal expansion, etc., as well as formability of liquid crystal display devices with high quality and excellent durability An adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred.
[0090]
The adhesive layer is, for example, natural or synthetic resins, in particular, tackifier resins, fillers or pigments made of glass fibers, glass beads, metal powders, other inorganic powders, colorants, antioxidants, etc. It may contain an additive to be added to the adhesive layer. Moreover, the adhesion layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient.
[0091]
Attachment of the adhesive layer to one side or both sides of the optical film can be performed by an appropriate method. For example, a pressure sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a suitable solvent alone or a mixture such as toluene and ethyl acetate is prepared. A method in which it is directly attached on a polarizing plate or an optical film by an appropriate development method such as a casting method or a coating method, or an adhesive layer is formed on a separator in accordance with the above, and this is applied to a polarizing plate or an optical film The method of transferring to is included.
[0092]
The pressure-sensitive adhesive layer can be provided on one side or both sides of a polarizing plate or an optical film as a superimposed layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as the adhesion layers of a different composition, a kind, thickness, etc. in the front and back of a polarizing plate or an optical film. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is generally 1 to 500 μm, preferably 5 to 200 μm, particularly preferably 10 to 100 μm.
[0093]
On the exposed surface of the adhesive layer, a separator is temporarily attached and covered for the purpose of preventing contamination until it is put to practical use. Thereby, it can prevent contacting an adhesion layer in the usual handling state. As the separator, except for the above thickness conditions, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, laminate thereof, and the like, silicone type or Appropriate ones according to the prior art, such as those coated with an appropriate release agent such as a long mirror alkyl type, fluorine type or molybdenum sulfide, can be used.
[0094]
In the present invention, the polarizer, transparent protective film, optical film, and the like that form the polarizing plate described above, and each layer such as an adhesive layer include, for example, salicylic acid ester compounds, benzophenol compounds, benzotriazole compounds, and cyanoacrylates. It may be a compound having an ultraviolet absorbing ability by a method such as a method of treating with an ultraviolet absorber such as a compound based on nickel or a nickel complex salt compound.
[0095]
The optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. In other words, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, an optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no limitation in particular except the point which uses a film, and it can apply according to the former. As the liquid crystal cell, any type such as a TN type, an STN type, or a π type can be used.
[0096]
An appropriate liquid crystal display device such as a liquid crystal display device in which the optical film is arranged on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the optical film according to the present invention can be installed on one side or both sides of the liquid crystal cell. When providing an optical film on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable layer such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.
[0097]
Next, an organic electroluminescence device (organic EL display device) will be described. Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescent light emitter). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, a structure having various combinations such as a laminate of such a light-emitting layer and an electron injection layer composed of a perylene derivative or the like, or a laminate of these hole injection layer, light-emitting layer, and electron injection layer is known. It has been.
[0098]
In organic EL display devices, holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the phosphor material. Then, light is emitted on the principle that the excited fluorescent material emits light when returning to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be expected from this, the current and the light emission intensity show strong nonlinearity with rectification with respect to the applied voltage.
[0099]
In an organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes must be transparent, and a transparent electrode usually formed of a transparent conductor such as indium tin oxide (ITO) is used as an anode. It is used as. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.
[0100]
In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror surface.
[0101]
In an organic EL display device comprising an organic electroluminescent light emitting device comprising a transparent electrode on the surface side of an organic light emitting layer that emits light upon application of a voltage and a metal electrode on the back side of the organic light emitting layer, the surface of the transparent electrode While providing a polarizing plate on the side, a retardation plate can be provided between the transparent electrode and the polarizing plate.
[0102]
Since the retardation plate and the polarizing plate have a function of polarizing light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization action. In particular, the mirror surface of the metal electrode can be completely shielded by configuring the retardation plate with a quarter-wave plate and adjusting the angle between the polarization direction of the polarizing plate and the retardation plate to π / 4. .
[0103]
That is, only the linearly polarized light component of the external light incident on the organic EL display device is transmitted by the polarizing plate. This linearly polarized light becomes generally elliptically polarized light by the phase difference plate, but becomes circularly polarized light especially when the phase difference plate is a quarter wave plate and the angle between the polarization direction of the polarizing plate and the phase difference plate is π / 4. .
[0104]
This circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, is again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and becomes linearly polarized light again on the retardation plate. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate | transmit a polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.
[0105]
【Example】
Hereinafter, the present invention will be described by way of examples. The liquid crystal polymer used in each example is as shown in the following chemical formulas 4-8. In the chemical formula, the numerical value outside the parentheses is mol%, and the liquid crystal polymer is displayed as a block body for convenience. The liquid crystal temperature range of the liquid crystal polymer is a value measured by polarizing microscope observation with a hot plate (heating stage) (Nikon Corporation, ECLIPSE E600POL). In the liquid crystal polymer, g: glass transition temperature (° C.), n: nematic liquid crystal temperature range, and i: isotropic phase transition temperature (° C.).
[0106]
Liquid crystal polymer 1: weight average molecular weight 8000
[Formula 4]

(G 90 ° C n 280 ° C i)
[0107]
Liquid crystal polymer 2: weight average molecular weight 6000
[Chemical formula 5]

(G 94 ° C n 255 ° C i)
[0108]
Liquid crystal polymer 3: weight average molecular weight 6000
[Chemical 6]

(G 96 ° C n 210 ° C i)
[0109]
Liquid crystal polymer 4: weight average molecular weight 35000
[Chemical 7]

(G 96 ° C n 290 ° C i)
[0110]
Liquid crystal polymer 5: weight average molecular weight 6000
[Chemical 8]

(G 95 ° C n 230 ° C i)
[0111]
(Surface free energy)
The surface free energy was measured with a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.) by a heating pendant drop method with the liquid crystal polymer at a liquid crystal temperature (150 ° C.).
[0112]
(viscosity)
Viscosity was measured with a rheometer Rheowin Pro manufactured by Haake with the liquid crystal polymer at the liquid crystal temperature (150 ° C.).
[0113]
Example 1
On a biaxially stretched polyethylene terephthalate (PET) film having a center line average roughness (Ra) of 15 nm, a solution prepared by dissolving the liquid crystal polymer 1 in cyclopentanone and adjusting the concentration to 15% by weight was applied by bar coating, 150 ° C. And dried for 2 minutes to prepare a liquid crystal film having a liquid crystal layer having a thickness of 1.2 μm.
[0114]
On the other hand, using a photomask on a glass substrate, a micro-processed polyimide alignment film (with a partially different rubbing direction) was formed.
[0115]
On the alignment film, the liquid crystal layer side of the liquid crystal film was thermally laminated at a temperature of 150 ° C. Then, after cooling to room temperature (23 degreeC), it peeled, peeling a PET film 180 degree | times, and the liquid crystal layer was transcribe | transferred to the orientation film | membrane on a glass substrate. Transferability was confirmed by visual and microscopic observation according to the following criteria as to whether or not transfer was possible without cohesive failure. ○: Good. X: There is a partial transfer defect. The results are shown in Table 1.
[0116]
Next, the liquid crystal layer was reoriented in the direction of the finely processed alignment film by heat treatment at 150 ° C. for 5 minutes. The orientation was confirmed according to the following criteria by observation with a polarizing microscope and visual observation with a sample placed between two polarizing plates on a light table. ○: Good. X: Not oriented. The results are shown in Table 1.
[0117]
After realignment by the heating, the nematic structure of the liquid crystal alignment layer was fixed by cooling to room temperature (23 ° C.). Thereafter, the repelling state of the surface of the liquid crystal alignment layer on the aligned glass substrate was visually observed using a polarizing microscope. ○: No repelling, good. X: There are many repellents of several μm. The results are shown in Table 1.
[0118]
Examples 2 and 3, Comparative Examples 1 and 2, Reference Example 1
In Example 1, the liquid crystal layer was aligned on the glass substrate in the same manner as in Example 1 except that the type of liquid crystal polymer and the center line average roughness (Ra) of the PET film were changed as shown in Table 1. Transcribed to. Further, in the same manner as in Example 1, the transferred liquid crystal layer was reoriented and then fixed. Further, the transferability and orientation of the liquid crystal layer and the repelling state of the surface of the obtained liquid crystal orientation layer were visually observed. The results are shown in Table 1.
[0119]
[Table 1]

From Table 1, it can be seen that the liquid crystal film of the present invention has good transferability and orientation, and can produce a liquid crystal alignment film with good yield. Moreover, when the surface roughness of a base film (PET film) is 20 nm, it turns out that the repelling state of the obtained liquid crystal aligning layer is good.
[Brief description of the drawings]
FIG. 1 is a conceptual cross-sectional view showing a method for producing a liquid crystal alignment film of the present invention.
[Explanation of symbols]
A liquid crystal film
1 Base film
2 Liquid crystal layer
2 'liquid crystal alignment layer
3 Other base materials (oriented base materials)

Claims (7)

A liquid crystal film in which a liquid crystal layer (2) is formed of a liquid crystal polymer on a base film (1), wherein the liquid crystal layer (2) has a liquid crystallinity at another orientation base material (3 ), And after bonding, only the base film (1) can be peeled off and transferred to the oriented base material (3). The transferred liquid crystal layer (2) uses a liquid crystal film that can be aligned at a temperature exhibiting liquid crystallinity,
A step of thermally laminating the liquid crystal layer (2) to the alignment substrate (3) at a temperature equal to or higher than the glass transition point of the liquid crystal polymer forming the liquid crystal layer (2);
After cooling below the glass transition point of the liquid crystal polymer, peeling the substrate film (1) and transferring the liquid crystal layer (2) to the alignment substrate (3);
Reheating to a temperature above the glass transition point of the liquid crystal polymer to align the liquid crystal layer (2) on the alignment substrate (3) to form a liquid crystal alignment layer (2 ');
Said cooling to a glass transition point below the temperature of the liquid crystal polymer, have a step, of fixing the orientation of the liquid crystal alignment layer (2 '),
The method for producing a liquid crystal alignment film, wherein the liquid crystal polymer has a viscosity of 500 to 50,000 [P] at a temperature exhibiting liquid crystallinity .   The method for producing a liquid crystal alignment film according to claim 1, wherein the alignment substrate (3) has a plurality of regions having different alignment directions. 3. The method for producing a liquid crystal alignment film according to claim 1 , wherein the liquid crystal polymer has a surface free energy of 400 μN / cm or less at a temperature exhibiting liquid crystallinity. 4. The liquid crystal alignment film according to claim 1 , wherein the liquid crystal layer (2) is formed by applying and drying a liquid crystal polymer on the base film (1). 5. Production method. The said base film (1) is an orientation base material, The liquid crystal polymer which forms a liquid-crystal layer (2) is orientating, The manufacture of the liquid crystal orientation film in any one of Claims 1-4 characterized by the above-mentioned. Method. The method for producing a liquid crystal alignment film according to claim 5, wherein the base film (1) is a biaxially stretched polyethylene terephthalate film. Center line average roughness (Ra) of the said base film (1) surface is 20 nm or less, The manufacturing method of the liquid crystal aligning film in any one of Claims 1-6 characterized by the above-mentioned.

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