JP4338001B2 - Liquid crystal alignment film - Google Patents
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Description
【０００１】
【産業上の利用分野】
本発明では、液晶ディスプレイ（液晶パネル）の製造等に用いられる液晶配向膜とその製造方法を提供するが、特に紫外光照射により分子鎖（官能基）を配向させるノンラビング製法において、従来のように直線偏光性の高い紫外光を用いる必要がなく、偏光度の低い紫外光の照射により、高生産性に大面積が得られる液晶配向膜とその製造方法を提供する。
【０００２】
【従来の技術】
液晶パネルに封入した液晶を配向させるのに液晶配向膜を用いている。液晶配向膜の多くは、表面形状や分子構造に異方性もつ高分子重合体膜であり、この種の液晶配向膜は液晶に接触配置することで、液晶内の分子配向を操作する作用がある。
液晶配向膜は、従来図２に示すように、基板（２１）にポリイミドなどの高分子化合物（＝重合体）（２２）を塗布し、表面をナイロンやポリエステル繊維を植毛した布（２４）を巻きつけたドラム（２３）で擦ることにより重合体表面に異方的な表面形状や分子構造を誘起し作製されてきた。このような高分子化合物（＝重合体）表面を植毛した布で物理的に擦るラビング方法は、配向膜の表面に微細な埃が付着したり静電気による放電が生じて、液晶パネルの製造工程において問題となっていた。
近年、上記のような問題点を解決するために、感光性の重合体の表面に非接触に（ノンラビング配向膜の製法）直線偏光性の紫外光を高分子化合物（＝重合体）に照射して液晶配向膜を製造する技術が注目されてきている。
この方法（図３）では、基板（１１’）に塗布した重合体（１２’）に、紫外線ランプ（１３’）からの非偏光（完全偏光成分が混在しない）を偏光素子（３４）により直線偏光に（偏光）変換して照射する必要がある。なぜならば、従来の配向膜となす重合体は、高い直線偏光性の紫外光を照射することではじめて異方性が発現して液晶配向能が得られるからである。
このような偏光変換に用いられる一般的な偏光素子としては、PVA（ポリビニルアルコール）を一軸延伸したシートにヨードを含浸したものをTAC（トリアセチルセルロース）で挟んだ２色性偏光子がある。しかしながら、このような２色性偏光子では、紫外域の光の透過率が低く耐熱性も低いため液晶光配向技術の使用には耐えない。このような理由から、紫外域の光を偏光させるには複屈折型プリズムが用いられているが、複屈折型プリズムでは方解石の自然結晶をプリズムとして用いるため、LCD（液晶ディスプレイ）等の大面積に用いるような基板全面を照射できるような大型プリズムはない。
非偏光を照射し配向能を発現させる方法として、唯一、アゾベンゼン系高分子材料の配向が報告されている（Appl. Phys. Lett., Vol73, No.7, 17 August 1998）。しかしながら、光異性化反応を用いているため、耐光性や耐熱性の面でも問題がある。
【０００３】
【発明が解決しようとする課題】
このように、照射光の直線偏光性を利用する従来の（ノンラビング法の）光配向膜および、その液晶光配向技術では、大面積照射を実現するには、実用的な高い偏光分離能を有する偏光素子の開発が課題であった。
【０００４】
【課題を解決する手段】
本発明では、研究の結果、低い偏光度の紫外光で異方性を発現する重合体との組み合わせにより、ノンラビング法で偏光度の低い紫外光を照射して得られる液晶配向膜の製造方法にいたった。
本発明では、化学式１または化学式２または化学式３で表される構造を有する共に、主鎖が炭化水素、アクリレート、メタクリレート、シロキサンなどである化学式４で表される単独重合体または共重合体塗布膜に、完全偏光成分と非偏光成分が混在する紫外光を照射することで重合体の感光性基の部分を２量化によって異方的に架橋せしめ、特別の偏光素子を用いることなしで液晶配向膜を形成し得る。
この解決手段により、ラビング処理における微細な埃や静電気による放電の発生、一定方向のみの配向が解決されるのみならず、直線偏光性の照射光を利用する液晶光配向技術（従来のノンラビング法）における、高い偏光分離能を有するとともに大面積照射が可能な偏光素子の開発が必要であるなどの従来技術の課題が解決される。
なお、本発明において用いられる、液晶配向能を発現するのに必要な完全偏光成分と非偏光成分が混在する紫外光は、光源より放射される照射光線の光路中に石英板などの透明基板（少なくとも１枚）を光路軸に対して傾斜配置するという比較的容易な手段により得ることでき、製造方法に面積的な限度もなく、大面積の液晶配向膜を高い生産性で得ることができる。
【０００５】
【発明の実施の形態】
以下に例を挙げて、本発明の詳細を説明する。
化学式４で示される単独重合体または共重合体は、液晶性高分子のメソゲン成分として多用されているビフェニル、ターフェニル、フェニルベンゾエート、アゾベンゼンなどの置換基と、化学式１または化学式２または化学式３で表される構造の感光性基を結合した構造の側鎖を有する、炭化水素、アクリレート、メタクリレート、シロキサンなどの構造を主鎖とする重合体である。
【０００６】
本発明の配向膜では、比較的偏光度の低い紫外光で液晶配向機能を付与できることが実験により確認された。例えば、化学式４において、Ｗ1＝化学式１、ｘ：ｙ＝１００：０、ｎ＝６、ｍ＝２、Ｘ＝none、−R1〜−R7＝−Hの本発明の配向膜材料では、基板上に製膜し、この基板に高圧水銀灯からの非偏紫外光を斜めに配置された石英板１枚を介して照射したとき、石英板への照射光の入射角度が５０°以上になると液晶配向能の発現が観察されることが判明した。
非偏光線が、空気と石英板のような二つの媒質界面を一部透過、一部反射するとき、透過光は完全偏光成分と非偏光成分が混在する光となる。ここで、非偏光線が石英板（屈折率：１．４５８５）に入射する場合を考える。石英板に入射する非偏光線のＰ成分とＳ成分の透過率および透過光の偏光度：Ｐ−Ｓ／Ｐ＋Ｓ（ＰとＳは、それぞれＰ成分とＳ成分の透過光強度であり、完全偏光成分の強度はＰ−Ｓで示され、Ｐ＋Ｓは完全偏光成分と非偏光成分を合わせた全透過光強度である。）は、石英板への非偏光線の入射角度によって変化し、図４に示す関係がある。本発明の材料では、石英板への非偏光線の入射角度が５０°以上のとき、言い換えれば、透過光の偏光度：Ｐ−Ｓ／Ｐ＋Ｓ×１００（％）＝１０．９（％）以上であれば、液晶配向能の付与が可能であることが実験により確認された。ここで、Ｐ成分の利用効率を考えれば、透明板への入射角は、Ｐ成分の透過率が１．０となる、透明板の屈折率により決まるブルースター角であることが望ましい。
【０００７】
図５を参照して説明する。
発明の高分子体（重合体）の溶液を基板上に塗布（スピンコートないしはキャスト）し塗布膜（５２）を形成する。製膜時は、該高分子塗布膜中の化学式１または化学式２または化学式３で表される構造の感光性基を有する側鎖は特定方向を向いておらず、該高分子塗布膜は等方性である。該高分子塗布膜（５２）に、光源より放射される非偏紫外光（Ｌｎ）の光路中に石英板などの透明基板（５４）（少なくとも１枚）を光路軸に対して傾斜配置（入射角θ'）し、完全偏光成分と非偏光成分が混在した紫外光（Ｌp）を照射することにより、化学式１または化学式２または化学式３で表される構造の感光性基の２量化した側鎖（５５）の密度が完全偏光成分の電界振動方向（Ｑ）で高くなり、結果として膜が異方性となる（図５：該図は、ブルースター角で透明基板（５４）へ非偏紫外光（Ｌｎ）が入射した場合の概略図であり、ＬｓはＳ成分の反射光である。）。この異方性の膜に液晶分子（５６）が接触すると膜との相互作用により、完全偏光成分の電界振動と平行方向に液晶分子が配向するようになる。このように、完全偏光成分の電界振動と平行方向に液晶分子が配向することから、完全偏光成分と非偏光成分が混在した紫外光を基板法線方向に対し傾斜（入射角ψ）して照射すると、TN型液晶セルにおいて配向欠陥を防ぐプレチルト角を発現することも可能である。
【０００８】
この２量化反応は、反応式（１）に示すようにシクロブタン結合を形成すると考えられており、この２量化反応を進めるには、化学式１または化学式２または化学式３で表される感光性基の部分が反応し得る波長の光の照射を要する。この波長は、化学式１または化学式２または化学式３で示された−R1〜−R9の種類によっても異なるが、一般に２００−５００ｎｍであり、中でも２５０−４００ｎｍの有効性が高い場合が多い。
【化５】
【０００９】
完全偏光成分と非偏光成分が混在する紫外光は、図１に示すように、紫外線ランプ（１３）、集光鏡（１５）、平面鏡（１６）、（１７）、インテグレータレンズ（１８）、コリメーターレンズ（１９）などから構成されている通常用いられている光照射装置の光路中ないしは光照射装置と基板（１１）に塗布した高分子化合物（重合体）（１２）の間に、透明板（１４）を傾斜配置するという比較的容易な手段により得ることができる。透明板として石英板（屈折率：１．４５８５）１枚を用いた場合、非偏光線の石英板への入射角度θが約５０°以上になるように、光照射装置の光路中ないしは光照射装置と被照射体の間に配置すればよく、大面積を配向処理可能な照射装置の作製も容易となる。
【００１０】
このようなことから、本発明の光配向膜およびその製造法では、高分子体の溶液を基板上に塗布（スピンコートないしはキャスト）して製膜し、該塗布膜に、完全偏光成分と非偏光成分が混在する紫外光を照射することにより、液晶配向膜を形成し得ることから、物理的に基板表面を擦るなどの工程が不要であるため、静電気、埃などを発生するという問題点が解決されるのみならず、石英板などの透明基板を照射光路中に斜めに配置するという比較的容易な手段により配向処理が可能なため、高い偏光分離能を有する偏光素子を用いることなく液晶表示装置を提供できる。
【００１１】
本発明の重合体に関する合成方法を以下に示す。
（重合体１）
４，４’−ビフェニルジオールと２−クロロエタノールを、アルカリ条件下で加熱することにより、４−ヒドロキシ−４’−ヒドロキシエトキシビフェニルを合成した。この生成物に、アルカリ条件下で１，６−ジブロモヘキサンを反応させ、４−（６−ブロモヘキシルオキシ）−４’−ヒドロキシエトキシビフェニルを合成した。次いで、リチウムメタクリレートを反応させ、４−ヒドロキシエトキシ−４’−（６’−ビフェニルオキシヘキシル）メタクリレートを合成した。最後に、塩基性の条件下において、塩化シンナモイルを加え、メタクリル酸エステル単量体を合成した。この単量体をテトラヒドロフラン中に溶解し、反応開始剤としてAIBN（アゾビスイソブチロニトリル）を添加して重合することにより、化学式５に示される重合体１を得た。
【化６】
（重合体２）
４，４’−ビフェニルジオールと２−クロロエタノールを、アルカリ条件下で加熱することにより、４−ヒドロキシ−４’−ヒドロキシエトキシビフェニルを合成した。この生成物に、アルカリ条件下で１，６−ジブロモヘキサンを反応させ、４−（６−ブロモヘキシルオキシ）−４’−ヒドロキシエトキシビフェニルを合成した。次いで、リチウムメタクリレートを反応させ、４−ヒドロキシエトキシ−４’−（６’−ビフェニルオキシヘキシル）メタクリレートを合成した。この生成物をテトラヒドロフラン中に溶解し、反応開始剤としてAIBN（アゾビスイソブチロニトリル）を添加して重合することにより側鎖末端に水酸基を有する重合体を得た。
これとは別に、β−（２−フリル）アクリル酸と塩化チオニルを反応させ合成したβ−（２−フリル）アクリル酸クロリドを、前記側鎖末端に水酸基を有する重合体とテトラヒドロフラン中で反応させることにより、化学式６に示される重合体２を得た。
【化７】
（重合体３）
４，４’−ビフェニルジオールと２−クロロエタノールを、アルカリ条件下で加熱することにより、４−ヒドロキシ−４’−ヒドロキシエトキシビフェニルを合成した。この生成物に、アルカリ条件下で１，６−ジブロモヘキサンを反応させ、４−（６−ブロモヘキシルオキシ）−４’−ヒドロキシエトキシビフェニルを合成した。次いで、リチウムメタクリレートを反応させ、４−ヒドロキシエトキシ−４’−（６’−ビフェニルオキシヘキシル）メタクリレートを合成した。この生成物をテトラヒドロフラン中に溶解し、反応開始剤としてAIBN（アゾビスイソブチロニトリル）を添加して重合することにより側鎖末端に水酸基を有する重合体を得た。
これとは別に、シンナミリデン酢酸と塩化チオニルを反応させ合成したシンナミリデン酢酸クロリドを、前記側鎖末端に水酸基を有する重合体とテトラヒドロフラン中で反応させることにより、化学式７に示される重合体３を得た。
【化８】
（重合体４）
４，４’−ビフェニルジオールと２−クロロエタノールを、アルカリ条件下で加熱することにより、４−ヒドロキシ−４’−ヒドロキシエトキシビフェニルを合成した。この生成物に、アルカリ条件下で１，６−ジブロモヘキサンを反応させ、４−（６−ブロモヘキシルオキシ）−４’−ヒドロキシエトキシビフェニルを合成した。次いで、リチウムメタクリレートを反応させ、４−ヒドロキシエトキシ−４’−（６’−ビフェニルオキシヘキシル）メタクリレートを合成した。この生成物をテトラヒドロフラン中に溶解し、反応開始剤としてAIBN（アゾビスイソブチロニトリル）を添加して重合することにより側鎖末端に水酸基を有する重合体を得た。
これとは別に、α−シアノシンナミリデン酢酸と塩化チオニルを反応させ合成したα−シアノシンナミリデン酢酸クロリドを、前記側鎖末端に水酸基を有する重合体とテトラヒドロフラン中で反応させることにより、化学式８に示される重合体４を得た。
【化９】
（実施例１）重合体１をクロロホルムに溶解し、ITO（インジウム錫酸化物）で覆った基板上に約１００ ｎｍの厚さでスピンコートした。該基板を水平面に対して４５度傾くように配置し、２ｍＷ／ｃｍ2の非偏紫外線を水平面に対し５０度傾くように配置した石英板を介し水平面に対し垂直方向から室温で５００秒間照射した。このような基板を２枚作製して液晶E７を充填することにより、厚さ４．５μｍのTN型液晶セルを組み立てた。このTN型液晶セルの駆動電圧は２Ｖであった。液晶セル全面にわたり配向欠陥のないことが確認された。
【００１６】
（実施例２）重合体２をクロロホルムに溶解し、ITO（インジウム錫酸化物）で覆った基板上に約１００ ｎｍの厚さでスピンコートした。該基板を水平面に対して４５度傾くように配置し、２ｍＷ／ｃｍ2の非偏紫外線を水平面に対し５０度傾くように配置した石英板を介し水平面に対し垂直方向から室温で２０秒間照射した。このような基板を２枚作製して液晶E７を充填することにより、厚さ４．５μｍのTN型液晶セルを組み立てた。このTN型液晶セルの駆動電圧は２Ｖであった。液晶セル全面にわたり配向欠陥のないことが確認された。
【００１７】
（実施例３）重合体３をクロロホルムに溶解し、ITO（インジウム錫酸化物）で覆った基板上に約１００ ｎｍの厚さでスピンコートした。該基板を水平面に対して４５度傾くように配置し、２ｍＷ／ｃｍ2の非偏紫外線を水平面に対し５０度傾くように配置した石英板を介し水平面に対し垂直方向から室温で１５０秒間照射した。このような基板を２枚作製して液晶E７を充填することにより、厚さ４．５μｍのTN型液晶セルを組み立てた。このTN型液晶セルの駆動電圧は２Ｖであった。液晶セル全面にわたり配向欠陥のないことが確認された。
【００１８】
（実施例４）重合体４をクロロホルムに溶解し、ITO（インジウム錫酸化物）で覆った基板上に約１００ ｎｍの厚さでスピンコートした。該基板を水平面に対して４５度傾くように配置し、２ｍＷ／ｃｍ2の非偏紫外線を水平面に対し５０度傾くように配置した石英板を介し水平面に対し垂直方向から室温で１００秒間照射した。このような基板を２枚作製して液晶E７を充填することにより、厚さ４．５μｍのTN型液晶セルを組み立てた。このTN型液晶セルの駆動電圧は２Ｖであった。液晶セル全面にわたり配向欠陥のないことが確認された。
【００１９】
【発明の効果】
以上に記述したように、本発明によれば、完全偏光成分と非偏光成分が混在する紫外光を照射することにより液晶配向膜が得られることから、石英板などの透明基板を少なくとも１枚照射光路中に斜めに配置するという比較的容易な手段により液晶配向の形成が可能になると共に、この膜を液晶ディスプレイ用の配向膜に応用できる。これにより、高い偏光分離能を有する偏光素子が不要となるため、従来の光配向技術で困難であった大面積の光配向処理も容易になる。また、高分子体表面を物理的に擦るラビング処理による液晶分子の配向操作が不要な配向膜が調製されるので、液晶ディスプレイの組立工程で生じる欠陥が著しく低減される。
【図面の簡単な説明】
【図１】本発明の配向膜の製造方法を示す概念図
【図２】従来のラビング配向膜の製造方法を示す例図
【図３】従来の光配向膜の製造方法（ノンラビング）を示す例図
【図４】石英板（屈折率：１．４５８５）に入射する非偏光線の入射角度とＰ成分とＳ成分の透過率および透過光の偏光度：Ｐ−Ｓ／（Ｐ＋Ｓ）×１００（％）の関係を示す。
【図５】発明の重合体塗布膜に発明の紫外光を照射した状態を示す模式図
【符号の説明】
１１・・・基板
１２・・・高分子化合物（重合体）
１３・・・紫外線ランプ
１４・・・透明板（石英板）
１５・・・集光鏡
１６、１７・・平面鏡
１８・・・インテグレータレンズ
１９・・・コリメータレンズ
５２・・・高分子（重合体）塗布膜
５４・・・透明基板
５５・・・２量化した側鎖
５６・・・液晶分子
Ｌｎ・・・非偏紫外光
Ｌｐ・・・完全偏光成分と非偏光成分が混在した紫外光
θ、θ’・・透明板への光線の入射角
ψ、ψ’、ψ”・・重合体体塗布膜への光線の入射角[0001]
[Industrial application fields]
In the present invention, a liquid crystal alignment film used for manufacturing a liquid crystal display (liquid crystal panel) and the manufacturing method thereof are provided. In particular, in a non-rubbing manufacturing method in which molecular chains (functional groups) are aligned by irradiation with ultraviolet light, It is not necessary to use ultraviolet light with high linear polarization, and a liquid crystal alignment film capable of obtaining a large area with high productivity by irradiation with ultraviolet light with low polarization degree and a method for producing the same.
[0002]
[Prior art]
A liquid crystal alignment film is used to align the liquid crystal sealed in the liquid crystal panel. Most liquid crystal alignment films are polymer films that have anisotropy in the surface shape and molecular structure, and this type of liquid crystal alignment film has the effect of manipulating the molecular alignment in the liquid crystal by being placed in contact with the liquid crystal. is there.
Conventionally, as shown in FIG. 2, the liquid crystal alignment film is obtained by applying a cloth (24) in which a high molecular compound (= polymer) (22) such as polyimide is applied to a substrate (21) and the surface is planted with nylon or polyester fibers. It has been produced by inducing an anisotropic surface shape or molecular structure on the polymer surface by rubbing with a wound drum (23). The rubbing method in which the surface of such a polymer compound (= polymer) is physically rubbed with a flocked cloth causes fine dust to adhere to the surface of the alignment film or discharge due to static electricity. It was a problem.
In recent years, in order to solve the above-mentioned problems, the surface of a photosensitive polymer is contacted non-contactly (a method for producing a non-rubbed alignment film), and linearly polarized ultraviolet light is irradiated to a polymer compound (= polymer). Thus, a technique for manufacturing a liquid crystal alignment film has been attracting attention.
In this method (FIG. 3), non-polarized light (completely polarized components are not mixed) from the ultraviolet lamp (13 ′) is linearly applied to the polymer (12 ′) applied to the substrate (11 ′) by the polarizing element (34). It is necessary to irradiate with polarized light (polarized light). This is because the polymer that forms the conventional alignment film exhibits anisotropy and provides liquid crystal alignment ability only when irradiated with highly linearly polarized ultraviolet light.
As a general polarizing element used for such polarization conversion, there is a dichroic polarizer in which a sheet of PVA (polyvinyl alcohol) uniaxially stretched and impregnated with iodine is sandwiched by TAC (triacetyl cellulose). However, such a dichroic polarizer cannot withstand the use of the liquid crystal photo-alignment technique because it has low ultraviolet light transmittance and low heat resistance. For this reason, birefringent prisms are used to polarize light in the ultraviolet region, but natural crystals of calcite are used as prisms in birefringent prisms, so large areas such as LCDs (liquid crystal displays) are used. There is no large prism that can irradiate the entire surface of the substrate used in the above.
The only method for irradiating non-polarized light to develop the orientation ability is the orientation of azobenzene polymer materials (Appl. Phys. Lett., Vol 73, No. 7, 17 August 1998). However, since a photoisomerization reaction is used, there is a problem in terms of light resistance and heat resistance.
[0003]
[Problems to be solved by the invention]
As described above, the conventional (non-rubbing) photo-alignment film using the linear polarization property of the irradiation light and the liquid crystal photo-alignment technology have a practically high polarization separation capability in order to realize large-area irradiation. Development of a polarizing element having a problem has been a problem.
[0004]
[Means for solving the problems]
In the present invention, as a result of research, a method for producing a liquid crystal alignment film obtained by irradiating ultraviolet light having a low degree of polarization by a non-rubbing method in combination with a polymer that exhibits anisotropy by ultraviolet light having a low degree of polarization I went to.
In the present invention, a homopolymer or copolymer coating film having a structure represented by Chemical Formula 1, Chemical Formula 2, or Chemical Formula 3 and having a main chain of hydrocarbon, acrylate, methacrylate, siloxane, etc., represented by Chemical Formula 4 In addition, the photosensitive group portion of the polymer is anisotropically crosslinked by irradiation with ultraviolet light in which a completely polarized component and a non-polarized component are mixed, and a liquid crystal alignment film is used without using a special polarizing element. Can be formed.
This solution not only solves the occurrence of discharge due to fine dust and static electricity in the rubbing process and alignment in a certain direction, but also liquid crystal photo alignment technology using linearly polarized light (conventional non-rubbing method) The problems of the prior art, such as the need to develop a polarizing element having a high polarization separation capability and capable of large area irradiation, are solved.
It should be noted that the ultraviolet light used in the present invention, in which a completely polarized component and a non-polarized component necessary for expressing the liquid crystal alignment ability are mixed, is a transparent substrate (such as a quartz plate) in the optical path of the irradiation light emitted from the light source. At least one sheet) can be obtained by a relatively easy means of being arranged at an inclination with respect to the optical path axis, and there is no area limitation in the manufacturing method, and a large-area liquid crystal alignment film can be obtained with high productivity.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The details of the present invention will be described below with reference to examples.
The homopolymer or copolymer represented by Chemical Formula 4 is a substituent such as biphenyl, terphenyl, phenylbenzoate, or azobenzene, which is frequently used as a mesogenic component of a liquid crystal polymer, and Chemical Formula 1 or Chemical Formula 2 or Chemical Formula 3. It is a polymer having a main chain of a structure such as hydrocarbon, acrylate, methacrylate, siloxane, etc., having a side chain having a structure in which a photosensitive group having the structure shown is bonded.
[0006]
In the alignment film of the present invention, it was confirmed by experiments that a liquid crystal alignment function can be imparted with ultraviolet light having a relatively low degree of polarization. For example, in the alignment film material of the present invention where W 1 = Chemical Formula 1, x: y = 100: 0, n = 6, m = 2, X = none, −R 1 to −R 7 = −H When an unpolarized ultraviolet light from a high-pressure mercury lamp is irradiated on the substrate through one quartz plate arranged obliquely, the incident angle of the irradiation light on the quartz plate is 50 ° or more. Then, it was found that the liquid crystal alignment ability was observed.
When non-polarized light partially transmits and partially reflects the interface between two media such as air and a quartz plate, the transmitted light becomes light in which a completely polarized component and a non-polarized component are mixed. Here, consider a case where non-polarized light is incident on a quartz plate (refractive index: 1.4585). P component and S component transmittance of unpolarized light incident on the quartz plate and degree of polarization of transmitted light: P−S / P + S (P and S are transmitted light intensities of the P component and S component, respectively, The intensity of the component is indicated by P−S, and P + S is the total transmitted light intensity including the completely polarized component and the unpolarized component.) Varies depending on the incident angle of the unpolarized light beam on the quartz plate, and is shown in FIG. There is a relationship to show. In the material of the present invention, when the incident angle of non-polarized light on the quartz plate is 50 ° or more, in other words, the degree of polarization of transmitted light: P−S / P + S × 100 (%) = 10.9 (%) or more Then, it was confirmed by experiment that liquid crystal alignment ability could be imparted. Here, considering the utilization efficiency of the P component, it is desirable that the incident angle to the transparent plate is a Brewster angle determined by the refractive index of the transparent plate so that the transmittance of the P component is 1.0.
[0007]
This will be described with reference to FIG.
A solution of the polymer (polymer) of the invention is applied (spin coated or cast) on a substrate to form a coating film (52). At the time of film formation, the side chain having a photosensitive group having a structure represented by chemical formula 1, chemical formula 2 or chemical formula 3 in the polymer coated film is not oriented in a specific direction, and the polymer coated film is isotropic. It is sex. On the polymer coating film (52), a transparent substrate (54) (at least one piece) such as a quartz plate is disposed inclined (incident on the optical path axis) in the optical path of non-polarized ultraviolet light (Ln) emitted from the light source. Angle θ ′) and irradiation with ultraviolet light (Lp) in which a completely polarized component and a non-polarized component are mixed, thereby dimerizing a side chain of a photosensitive group having a structure represented by Chemical Formula 1, Chemical Formula 2, or Chemical Formula 3. The density of (55) becomes higher in the electric field oscillation direction (Q) of the completely polarized component, and as a result, the film becomes anisotropic (FIG. 5: The figure shows non-polarized ultraviolet rays toward the transparent substrate (54) at the Brewster angle. It is the schematic when light (Ln) injects, Ls is the reflected light of S component. When the liquid crystal molecules (56) come into contact with this anisotropic film, the liquid crystal molecules are aligned in a direction parallel to the electric field vibration of the completely polarized component due to the interaction with the film. In this way, the liquid crystal molecules are aligned in a direction parallel to the electric field vibration of the completely polarized component, so that ultraviolet light mixed with the completely polarized component and the non-polarized component is tilted (incident angle ψ) with respect to the substrate normal direction. Then, it is also possible to develop a pretilt angle that prevents alignment defects in the TN liquid crystal cell.
[0008]
This dimerization reaction is considered to form a cyclobutane bond as shown in the reaction formula (1). In order to proceed with this dimerization reaction, the photosensitive group represented by the chemical formula 1, the chemical formula 2 or the chemical formula 3 is used. It is necessary to irradiate with light having a wavelength at which the part can react. This wavelength varies depending on the type of -R 1 to -R 9 represented by Chemical Formula 1, Chemical Formula 2, or Chemical Formula 3, but is generally 200-500 nm, and in particular, the effectiveness of 250-400 nm is often high.
[Chemical formula 5]
[0009]
As shown in FIG. 1, the ultraviolet light in which a completely polarized component and a non-polarized component are mixed includes an ultraviolet lamp (13), a collecting mirror (15), a plane mirror (16), (17), an integrator lens (18), a collimator. A transparent plate in the optical path of a commonly used light irradiation device composed of a meter lens (19) or between the light irradiation device and the polymer compound (polymer) (12) applied to the substrate (11) (14) can be obtained by a relatively easy means of arranging in an inclined manner. When one quartz plate (refractive index: 1.4585) is used as the transparent plate, the light irradiation device is in the optical path or light irradiation so that the incident angle θ of the non-polarized light to the quartz plate is about 50 ° or more. What is necessary is just to arrange | position between an apparatus and a to-be-irradiated body, and manufacture of the irradiation apparatus which can orientate a large area also becomes easy.
[0010]
For this reason, in the photo-alignment film and the method for producing the same of the present invention, a polymer solution is coated (spin coated or cast) on a substrate to form a film, and the coating film is coated with a completely polarized component and a non-polarized component. Since a liquid crystal alignment film can be formed by irradiating with ultraviolet light mixed with polarized light components, a process such as physically rubbing the surface of the substrate is unnecessary, which causes problems such as generation of static electricity and dust. Not only can this be solved, but alignment processing can be performed by a relatively easy means of placing a transparent substrate such as a quartz plate obliquely in the irradiation light path, so that a liquid crystal display can be used without using a polarizing element having high polarization separation ability. Equipment can be provided.
[0011]
A synthesis method for the polymer of the present invention is shown below.
(Polymer 1)
4-Hydroxy-4'-hydroxyethoxybiphenyl was synthesized by heating 4,4'-biphenyldiol and 2-chloroethanol under alkaline conditions. This product was reacted with 1,6-dibromohexane under alkaline conditions to synthesize 4- (6-bromohexyloxy) -4′-hydroxyethoxybiphenyl. Subsequently, lithium methacrylate was reacted to synthesize 4-hydroxyethoxy-4 ′-(6′-biphenyloxyhexyl) methacrylate. Finally, cinnamoyl chloride was added under basic conditions to synthesize methacrylate monomers. This monomer was dissolved in tetrahydrofuran, and polymerized by adding AIBN (azobisisobutyronitrile) as a reaction initiator to obtain Polymer 1 represented by Chemical Formula 5.
[Chemical 6]
(Polymer 2)
4-Hydroxy-4'-hydroxyethoxybiphenyl was synthesized by heating 4,4'-biphenyldiol and 2-chloroethanol under alkaline conditions. This product was reacted with 1,6-dibromohexane under alkaline conditions to synthesize 4- (6-bromohexyloxy) -4′-hydroxyethoxybiphenyl. Subsequently, lithium methacrylate was reacted to synthesize 4-hydroxyethoxy-4 ′-(6′-biphenyloxyhexyl) methacrylate. This product was dissolved in tetrahydrofuran and polymerized by adding AIBN (azobisisobutyronitrile) as a reaction initiator to obtain a polymer having a hydroxyl group at the end of the side chain.
Separately, β- (2-furyl) acrylic acid chloride synthesized by reacting β- (2-furyl) acrylic acid with thionyl chloride is reacted in tetrahydrofuran with a polymer having a hydroxyl group at the end of the side chain. As a result, the polymer 2 represented by the chemical formula 6 was obtained.
[Chemical 7]
(Polymer 3)
4-Hydroxy-4'-hydroxyethoxybiphenyl was synthesized by heating 4,4'-biphenyldiol and 2-chloroethanol under alkaline conditions. This product was reacted with 1,6-dibromohexane under alkaline conditions to synthesize 4- (6-bromohexyloxy) -4′-hydroxyethoxybiphenyl. Subsequently, lithium methacrylate was reacted to synthesize 4-hydroxyethoxy-4 ′-(6′-biphenyloxyhexyl) methacrylate. This product was dissolved in tetrahydrofuran and polymerized by adding AIBN (azobisisobutyronitrile) as a reaction initiator to obtain a polymer having a hydroxyl group at the end of the side chain.
Separately, cinnamylidene acetic acid chloride synthesized by reacting cinnamylidene acetic acid and thionyl chloride was reacted in tetrahydrofuran with a polymer having a hydroxyl group at the end of the side chain to obtain polymer 3 represented by chemical formula 7. .
[Chemical 8]
(Polymer 4)
4-Hydroxy-4'-hydroxyethoxybiphenyl was synthesized by heating 4,4'-biphenyldiol and 2-chloroethanol under alkaline conditions. This product was reacted with 1,6-dibromohexane under alkaline conditions to synthesize 4- (6-bromohexyloxy) -4′-hydroxyethoxybiphenyl. Subsequently, lithium methacrylate was reacted to synthesize 4-hydroxyethoxy-4 ′-(6′-biphenyloxyhexyl) methacrylate. This product was dissolved in tetrahydrofuran and polymerized by adding AIBN (azobisisobutyronitrile) as a reaction initiator to obtain a polymer having a hydroxyl group at the end of the side chain.
Separately, α-cyanocinnamylidene acetate chloride synthesized by reacting α-cyanocinnamylideneacetic acid and thionyl chloride is reacted with a polymer having a hydroxyl group at the side chain end in tetrahydrofuran to obtain a chemical formula. 8 was obtained.
[Chemical 9]
Example 1 The polymer 1 was dissolved in chloroform and spin-coated at a thickness of about 100 nm on a substrate covered with ITO (indium tin oxide). The substrate was placed so as to be inclined at 45 degrees with respect to the horizontal plane, and 2 mW / cm 2 of unpolarized ultraviolet rays were irradiated for 500 seconds at room temperature from a direction perpendicular to the horizontal plane through a quartz plate placed so as to be inclined at 50 degrees with respect to the horizontal plane. . Two such substrates were prepared and filled with liquid crystal E7 to assemble a TN type liquid crystal cell having a thickness of 4.5 μm. The drive voltage of this TN type liquid crystal cell was 2V. It was confirmed that there was no alignment defect over the entire liquid crystal cell.
[0016]
(Example 2) The polymer 2 was dissolved in chloroform and spin-coated at a thickness of about 100 nm on a substrate covered with ITO (indium tin oxide). The substrate was arranged to be inclined at 45 degrees with respect to the horizontal plane, and 2 mW / cm 2 of unpolarized ultraviolet rays were irradiated for 20 seconds at room temperature from a direction perpendicular to the horizontal plane through a quartz plate arranged to be inclined at 50 degrees with respect to the horizontal plane. . Two such substrates were prepared and filled with liquid crystal E7 to assemble a TN type liquid crystal cell having a thickness of 4.5 μm. The drive voltage of this TN type liquid crystal cell was 2V. It was confirmed that there was no alignment defect over the entire liquid crystal cell.
[0017]
Example 3 The polymer 3 was dissolved in chloroform and spin-coated at a thickness of about 100 nm on a substrate covered with ITO (indium tin oxide). The substrate was placed so as to be inclined at 45 degrees with respect to the horizontal plane, and 2 mW / cm 2 of unpolarized ultraviolet rays were irradiated for 150 seconds at room temperature from a direction perpendicular to the horizontal plane through a quartz plate placed so as to be inclined at 50 degrees with respect to the horizontal plane. . Two such substrates were prepared and filled with liquid crystal E7 to assemble a TN type liquid crystal cell having a thickness of 4.5 μm. The drive voltage of this TN type liquid crystal cell was 2V. It was confirmed that there was no alignment defect over the entire liquid crystal cell.
[0018]
Example 4 The polymer 4 was dissolved in chloroform and spin-coated at a thickness of about 100 nm on a substrate covered with ITO (indium tin oxide). The substrate was arranged to be inclined at 45 degrees with respect to the horizontal plane, and 2 mW / cm 2 of unpolarized ultraviolet rays were irradiated for 100 seconds at room temperature from a direction perpendicular to the horizontal plane through a quartz plate arranged to be inclined at 50 degrees with respect to the horizontal plane. . Two such substrates were prepared and filled with liquid crystal E7 to assemble a TN type liquid crystal cell having a thickness of 4.5 μm. The drive voltage of this TN type liquid crystal cell was 2V. It was confirmed that there was no alignment defect over the entire liquid crystal cell.
[0019]
【The invention's effect】
As described above, according to the present invention, since a liquid crystal alignment film can be obtained by irradiating ultraviolet light in which a completely polarized component and a non-polarized component are mixed, at least one transparent substrate such as a quartz plate is irradiated. The liquid crystal alignment can be formed by a relatively easy means of being arranged obliquely in the optical path, and this film can be applied to an alignment film for a liquid crystal display. This eliminates the need for a polarizing element having a high polarization separation capability, and facilitates large-area photo-alignment processing that has been difficult with conventional photo-alignment techniques. Further, since an alignment film that does not require alignment operation of liquid crystal molecules by rubbing treatment that physically rubs the surface of the polymer body is prepared, defects generated in the assembly process of the liquid crystal display are remarkably reduced.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a method for producing an alignment film of the present invention. FIG. 2 is an example showing a method for producing a conventional rubbing alignment film. FIG. 3 shows a method for producing a conventional photo-alignment film (non-rubbing). FIG. 4 shows an incident angle of non-polarized light incident on a quartz plate (refractive index: 1.4585), transmittance of P component and S component, and degree of polarization of transmitted light: PS / (P + S) × 100. (%) Relationship is shown.
FIG. 5 is a schematic diagram showing a state in which the polymer coating film of the invention is irradiated with the ultraviolet light of the invention.
11 ...
13 ...
15 ...
Claims (1)
ｘ：ｙ＝１００〜０：０〜１００、ｎ＝１〜１２、ｍ＝１〜１２、ｊ＝１〜１２、Ｘ，Ｙ＝none、−COO、−OCO−、−N=N−、−C=C−or−C 6 H 4 −、Ｗ 1 ，Ｗ 2 ＝化学式１または化学式２または化学式３で表される構造である。 A photo-alignment polymer applied on a substrate , that is, a main chain selected from hydrocarbon, acrylate, methacrylate, and siloxane, and a photosensitive group having a structure represented by Chemical Formula 1, Chemical Formula 2, or Chemical Formula 3. UV light in which a completely polarized component and a non-polarized component are mixed with a polymer represented by the chemical formula 4 formed by bonding with a substituent of a liquid crystalline polymer selected from biphenyl, terphenyl, phenylbenzoate, and azobenzene A liquid crystal alignment film characterized by aligning liquid crystal molecules in a direction parallel to the electric field vibration direction of a completely polarized component and imparting a liquid crystal alignment function.
x: y = 100-0: 0-100, n = 1-12, m = 1-12, j = 1-12, X, Y = none, -COO, -OCO-, -N = N-,- C = C-or-C 6 H 4 -, a structure represented by W 1, W 2 = formula 1 or formula 2 or 3.
Priority Applications (4)
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| JP30045599A JP4338001B2 (en) | 1999-10-22 | 1999-10-22 | Liquid crystal alignment film |
| TW089100508A TW500747B (en) | 1999-01-19 | 2000-01-14 | Alignment layer and a liquid crystal display using the same |
| US09/484,698 US6696114B1 (en) | 1999-01-19 | 2000-01-18 | Alignment layer and a liquid crystal display using the same |
| KR1020000002339A KR100639536B1 (en) | 1999-01-19 | 2000-01-19 | Alignmemt layer, and a liquid crystal display using the same |
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| JP30045599A JP4338001B2 (en) | 1999-10-22 | 1999-10-22 | Liquid crystal alignment film |
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| KR101221213B1 (en) * | 2005-12-29 | 2013-01-11 | 엘지디스플레이 주식회사 | light irradiating equipment |
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