JP4132779B2 - Selective reflective film and manufacturing method thereof - Google Patents

Description

【００６３】
上記構造式において、ｍは１〜８の整数を表し、１〜３の整数が好ましい。また、ｎは１〜１０の整数を表し、１〜５の整数が好ましい。
【００６４】
本発明においては、可視光領域に異性化可能な吸収を有する光反応型キラル化合物は、二種以上を併用してもよいし、一種単独で用いてもよい。また、該光反応型キラル化合物と共に、公知の光反応型キラル化合物や非光反応型キラル化合物を併用することもできる。
【００６５】
可視光領域に異性化可能な吸収を有する光反応型キラル化合物の含有量としては、「重合性基を少なくとも１つ有する液晶性化合物」に該光反応型キラル化合物を均一に溶解後、加熱して液晶状態を示す温度で観察、測定される選択反射波長に基づいて算出される、該選択反射波長の中心波長が４００ｎｍとなる量以下が好ましい。この量を超えると、配向劣化や感度低下を生ずることがある。
また、光反応型キラル化合物の、光照射により変化する捻れ力の光照射前後でのＨＴＰ差（ΔＨＴＰ）にその重量百分率を乗算したものが１．０７以上となる量以上が好ましい。この量未満であると、色相幅の広い（即ち、選択反射する波長領域の広い）多色パターニングが困難となることがある。ここで、ＨＴＰとは、光の照射により変化する液晶の螺旋ピッチ、即ち螺旋構造の捻れ力（ヘリカルツイスティングパワー）をいい、その差（ΔＨＴＰ）とは、光照射により光照射前後で変化する螺旋ピッチの差をいう。
【００６６】
−重合性基を少なくとも１つ有する液晶性化合物−
重合性基を少なくとも１つ有する液晶性化合物（本明細書中、単に「液晶性化合物」ということがある。）としては、重合性基を有する公知の液晶性化合物から適宜選択することができ、中でも、棒状のネマチック液晶化合物（以下、単に「ネマチック液晶化合物」という。）が好ましい。
【００６７】
ネマチック液晶化合物としては、その屈折率異方性Δｎが、０．１０〜０．４０の液晶化合物、高分子液晶化合物、重合性液晶化合物の中から適宜選択することができる。ネマチック液晶化合物に光反応型キラル化合物を併用することによって、コレステリック液晶組成物とすることができる。また、前記ネマチック液晶化合物は、溶融時の液晶状態にある間に、例えばラビング処理等の配向処理を施した配向基板を用いる等により配向させることができる。また、液晶状態を固相にして固定化する場合には、冷却、重合等の手段を用いることができる。即ち、液晶性化合物は重合性基を有し、かつその反応性が極めて高いため、配向状態で効率よく重合させると強靭な膜を形成することができる。
【００６８】
前記ネマチック液晶化合物の中でも、例えば、紫外線に感応して重合硬化するＵＶ硬化型の官能基（例えば、アクリレート基等）が同一分子内に導入された液晶化合物などが好適に挙げられる。これに紫外線照射して固めれば、１２０℃以下の低温で膜強度の高いカラーフィルタの作製が可能である。
【００６９】
前記ネマチック液晶化合物の具体例としては、下記化合物を挙げることができる。但し、本発明においては、これらに制限されるものではない。
【００７０】
【化２】

【００７１】
【化３】

【００７２】
【化４】

【００７３】
前記式中、ｎは、１〜１０００の整数を表す。
前記各例示化合物においては、芳香環の側鎖連結基が以下の構造に変わったものも同様に好適なものとして挙げることができる。
【００７４】
【化５】

【００７５】
上記のうち、ネマチック液晶化合物としては、硬化性に優れ、層の耐熱性を確保しうる観点からは、分子内に重合性基あるいは架橋性基を有する化合物が好ましい。
【００７６】
前記液晶性化合物は、一種単独で用いてもよいし二種以上を併用してもよい。また、「重合性基を少なくとも１つ有する液晶性化合物」と共に、重合性基を有しない液晶性化合物を併用してもよい。
前記「重合性基を少なくとも１つ有する液晶性化合物」の含有量としては、液晶性組成物（コレステリック液晶組成物）の全固形分（質量）に対して、３０〜９８質量％が好ましく、５０〜９５質量％がより好ましい。前記含有量が３０質量％未満であると、配向が不十分となり所望の選択反射色が得られないことがある。
【００７７】
−重合開始剤−
前記重合開始剤は、不飽和結合に基づく重合反応を促進し、液晶性組成物を重合硬化して固定化すると共に、固定化後の液晶性組成物の強度をより向上させる。重合開始剤としては、光反応性、熱反応性等の公知の化合物から適宜選択でき、中でも、光照射によって反応を促進し得る光重合開始剤が好適である。例えばコレステリック液晶組成物などの重合硬化反応を迅速に行うことができ、大きい固有複屈折（Δｎ）や、高解像度、色純度の高い選択反射色を安定的に得ることができる。
【００７８】
前記光重合開始剤としては、公知のものの中から適宜選択することができ、例えば、ｐ−メトキシフェニル−２，４−ビス（トリクロロメチル）−ｓ−トリアジン、２−（ｐ−ブトキシスチリル）−５−トリクロロメチル１，３，４−オキサジアゾール、９−フェニルアクリジン、９，１０−ジメチルベンズフェナジン、ベンゾフェノン／ミヒラーズケトン、ヘキサアリールビイミダゾール／メルカプトベンズイミダゾール、ベンジルジメチルケタール、チオキサントン／アミン等が挙げられる。
【００７９】
前記重合開始剤の添加量としては、液晶性組成物の固形分（質量）の０．１〜２０質量％が好ましく、０．５〜５質量％がより好ましい。前記添加量が、０．１質量％未満であると、硬化効率が低いため長時間を要することがあり、２０質量％を越えると、例えば光重合開始剤の場合に紫外線領域から可視光領域での光透過率が劣ることがある。
【００８０】
−空気界面配向剤−
空気界面配向剤とは、排除体積効果を有する界面活性剤である。ここで、排除体積効果を有するとは、液晶（分子）の空気界面側の配向制御、即ち、例えば塗布により液晶性組成物を含む層を形成した際の、該層表面の空気界面での液晶の空間的な配向状態を立体的に制御することをいう。具体的には、空気界面側の液晶分子のプレチルト角を制御することをいう。
【００８１】
好ましい空気界面配向剤の分子構造的な要件としては、フレキシブルな疎水性部位と環状ユニットを１つ以上備えた分子的にみて剛性を有するユニット（以下、剛直部位という。）とを有することである。なお、用いる液晶性化合物の種類によって、フレキシブルな疎水性部位をパーフルオロ鎖とすることもでき、長いアルキル鎖とすることもできる。疎水性部位がフレキシブルであることにより、効果的に疎水性部位を空気側に配置することができる。
また、空気界面配向剤は、分子数が数百程度の短分子であってもよく、それらが連結したポリマーやオリゴマーであってもよい。また、目的によって重合性の官能基を付与することも可能である。
【００８２】
このような空気界面配向剤を含有する場合には、空気界面配向剤のフレキシブルな疎水的部位が空気界面方向に存在し、かつ剛直部位が液晶分子方向に存在し、更に、剛直部位が平面的でそれが空気界面と平行に配列していることにより、液晶分子を空気界面に平行に配列させることが可能となる。
一方、剛直部位が空気界面と垂直に配列していれば、液晶分子を空気界面に垂直に配列させることが可能となる。
具体的には、ノニオン系の界面活性剤が好ましく、例えば下記化合物が好適に挙げられる。
【００８３】
【化６】

【００８４】
【化７】

【００８５】
前記空気界面配向剤の添加量としては、液晶性組成物を含む層の空気界面側の表面を一分子ほど覆う程度が好ましく、液晶性組成物の全固形分（質量）に対して、０．０５〜５質量％が好ましく、０．１〜１．０質量％がより好ましい。前記添加量が、０．０５質量％未満であると、その効果を発揮しないことがあり、５質量％を越えると、空気界面配向剤自体が会合を起こして液晶と相分離を起こすことがある。
なお、空気界面配向剤を含有することにより表面張力の低下が図られるが、さらに表面張力を低下させ、塗布性の向上を図る目的で、前記空気界面配向剤以外の界面活性剤を併用することもできる。
【００８６】
また、前記界面活性剤は、例えば、塗布液状の液晶性組成物を塗布し層形成する場合など、層表面の空気界面における液晶分子の配向状態を立体的に制御でき、特にコレステリック液晶の場合には、より色純度の高い選択反射波長を得ることができる。
【００８７】
−重合性モノマー−
液晶性組成物には、重合性モノマーを併用してもよい。該重合性モノマーを併用すると、パターニング（コレステリック液晶の場合は、光照射による液晶の捻れ力を変化させて選択反射波長の分布を形成）した後、その螺旋構造（選択反射性）を固定化し、固定化後の液晶層（液晶組成物）の強度をより向上させることができる。但し、前記ネマチック液晶化合物が同一分子内に不飽和結合を有する場合には、必ずしも添加する必要はない。
【００８８】
前記重合性モノマーとしては、例えば、エチレン性不飽和結合を持つモノマー等が挙げられ、具体的には、ペンタエリスリトールテトラアクリレート、ジペンタエリスリトールヘキサアクリレート等の多官能モノマーが挙げられる。
前記エチレン性不飽和結合を持つモノマーの具体例としては、以下に示す化合物を挙げることができる、但し、本発明においては、これらに限定されるものではない。
【００８９】
【化８】

【００９０】
前記重合性モノマーの添加量としては、液晶性組成物の全固形分（質量）の０．５〜５０質量％が好ましい。該添加量が、０．５質量％未満であると、十分な硬化性を得ることができないことがあり、５０質量％を越えると、液晶分子の配向を阻害し、十分な発色が得られないことがある。
【００９１】
−他の成分−
更に、他の成分として、バインダー樹脂、重合禁止剤、溶剤、増粘剤、色素、顔料、紫外線吸収剤、ゲル化剤等を添加することもできる。
該他の成分としては、紫外線硬化により硬化したカラーフィルタ膜の強度に影響するので、液晶性化合物との相溶性に優れるものが好ましい。
【００９２】
また、これらの成分が硬化されたカラーフィルタ膜中で移動可能であると、遊離した成分が膜強度を低下させ、カラーフィルタの諸特性にも変化を生じさせる。したがって、添加する他の成分としては、液晶性化合物に導入された重合性の官能基と同系統の官能基を持つ成分を使用することが好ましい。即ち、他の成分が膜中で遊離せずに重合硬化により液晶性化合物中に固定化されるので、膜強度、諸特性が阻害されることもないのである。また、バインダー樹脂及び界面活性剤を除く前記他の成分の含有量は、液晶性組成物の全固形分（質量）の１０質量％以下が好ましい。該含有量が１０質量％を超えると、光学膜（選択反射膜）の強度を低下させることがある。
【００９３】
前記バインダー樹脂としては、例えば、ポリスチレン、ポリ−α−メチルスチレン等のポリスチレン化合物、メチルセルロース、エチルセルロース、アセチルセルロース等のセルロース樹脂、側鎖にカルボキシル基を有する酸性セルロース誘導体、ポリビニルフォルマール、ポリビニルブチラール等のアセタール樹脂、特開昭５９−４４６１５号、特公昭５４−３４３２７号、特公昭５８−１２５７７号、特公昭５４−２５９５７号、特開昭５９−５３８３６号、特開昭５９−７１０４８号に記載のメタクリル酸共重合体、アクリル酸共重合体、イタコン酸共重合体、クロトン酸共重合体、マレイン酸共重合体、部分エステル化マレイン酸共重合体等が挙げられる。
また、アクリル酸アルキルエステルのホモポリマー及びメタアクリル酸アルキルエステルのホモポリマーも挙げられ、これらについては、特にアルキル基がメチル基、エチル基、ｎ−プロピル基、ｎ−ブチル基、ｉｓｏ−ブチル基、ｎ−ヘキシル基、シクロヘキシル基、２−エチルヘキシル基等のものが好適である。
その他、水酸基を有するポリマーに酸無水物を添加させたもの、ベンジル（メタ）アクリレート／（メタアクリル酸のホモポリマータ）アクリル酸共重合体やベンジル（メタ）アクリレート／（メタ）アクリル酸／他のモノマーの多元共重合体等が挙げられる。
【００９４】
上記の中でも、パターニング後のアルカリ現像性、及び量産性の観点からは、カルボキシル基を含むバインダー樹脂が好ましい。プラスチック基板上に液晶層を形成（塗布、転写等）する場合、塗布液状に調製するコレステリック液晶組成物にバインダー成分として、カルボキシル基を含むバインダー樹脂を用いると、アルカリ現像が可能であり、光照射後にアルカリ現像することによって簡易にパターニングを行うことができる。
【００９５】
液晶性組成物中におけるバインダー樹脂の含有量としては、０〜５０質量％が好ましく、０〜３０質量％がより好ましい。前記含有量が５０質量％を超えると、液晶性化合物の配向が不十分となることがある。
【００９６】
前記重合禁止剤は、保存性の向上の目的で添加され得る。例えば、ハイドロキノン、ハイドロキノンモノメチルエーテル、フェノチアジン、ベンゾキノン、及びこれらの誘導体等が挙げられる。該重合禁止剤の添加量としては、前記重合性モノマーに対して０〜１０質量％が好ましく、０〜５質量％がより好ましい。
【００９７】
液晶性組成物は、前記各成分を溶剤に溶解、分散して（塗布液状に）調製でき、これを任意の形状に成形し、あるいは支持体等の上に形成（好ましくは、例えば塗布により液晶性組成物層を形成）して用いることができる。塗布により液晶性組成物層を形成すると、層厚、表面性の均一な層が得られ、光学特性に優れた選択反射膜を形成することができる。
前記溶剤としては、例えば、２−ブタノン、シクロヘキサノン、塩化メチレン、クロロホルム等が挙げられる。
【００９８】
＜選択反射膜＞
本発明の選択反射膜は、既述の本発明の選択反射膜の製造方法により好適に作製することができる。より好ましくは、４９０〜５７０ｎｍ若しくは６３０〜６９０ｎｍの波長領域に異性化可能な吸収を有する液晶性組成物に、液晶の螺旋の捻れ方向と同方向であって、波長４９０〜５７０ｎｍ若しくは６３０〜６９０ｎｍの円偏光若しくは楕円偏光を画像様に照射してパターニングして作製できる。
【００９９】
したがって、本発明の選択反射膜は、塗布厚にムラがあるような場合であっても、該ムラ等に起因するパターニング時における色ムラの発生が効果的に抑制されてなるので、色相均一性（特に、緑色若しくは赤色の色相及びその均一性）に優れる。
【０１００】
最終的な選択反射膜の形態としては、特に制限はなく、前記液晶性組成物のみから構成されたシート形態、所望の支持体や仮支持体上に液晶性組成物を含む層（液晶層）を設けた形態、等のいずれであってもよく、更に配向膜や保護膜等の他の層（膜）が設けられていてもよい。
【０１０１】
所望の支持体や仮支持体上に液晶性組成物を含む層（液晶層）を設けた形態の場合、前記液晶層は、液晶性化合物（ネマチック液晶化合物）と光反応型キラル化合物と重合開始剤とをそれぞれ少なくとも一種含有するコレステリック液晶組成物よりなり、必要に応じて重合性モノマー、界面活性剤やバインダ樹脂等の他の成分を含んでいてもよい。
本発明においては、特に空気界面配向剤、重合性モノマーを併用することが好ましい。前記空気界面配向剤の含有により、既述のように、特に色純度の高い選択反射波長を得ることができる。
【０１０２】
以上のように、コレステリック液晶組成物を用いるので、非光吸収型の選択反射膜であって、液晶の選択反射する波長領域が拡く多彩な色相を示し、色純度（特に緑色、赤色）及びその均一性、並びに解像度に特に優れた選択反射膜であり、例えば、色純度の高い原色（Ｂ,Ｇ,Ｒ)よりなり、パターニング精度が高く色分画の良好な高解像度のカラーフィルタとすることができる。
【０１０３】
本発明の選択反射膜は、（積層）カラーフィルタのほか、ＬＣＤ等の表示デバイスに用いられる、位相差フィルム、円偏光反射板、透過型ＬＣＤ用の輝度向上フィルム等、カラーホイール等のプロジェクター等に用いられる光学部品、塗装等された装飾品、高光沢（メタリック）な印刷物、偽造防止用表示などに好適に用いることができる。
【０１０４】
【実施例】
以下、実施例により本発明を説明するが、本発明はこれらの実施例に限定されるものではない。
（実施例１）
(1) フィルタ基板の準備
ガラス基板上にポリイミド配向膜（ＬＸ−１４００，日立化成デュポン（株）製）塗布液をスピンコーターにより塗布し、１００℃のオーブンで５分間乾燥した後、２５０℃のオーブンで１時間焼成して配向膜を形成した。更に、該膜の表面をラビング処理により配向処理して配向膜付ガラス基板を作製した。
【０１０５】
(2) フィルタ層の形成
上記より得た配向膜付ガラス基板の該配向膜上に、下記処方にて調製した感光性液晶層用塗布液（１）をスピンコーターにより塗布し、これを１００℃のオーブンで２分間乾燥して感光性液晶層（液晶性組成物層）を形成した（層形成工程）。層厚を共焦点顕微鏡により測定したところ、２．３μｍであった。
【０１０６】
【化９】

【０１０７】
次いで、感光性液晶層が形成されたガラス基板を、該ガラス基板の表面で接触するように１００℃のホットプレート上に３分間保持し、感光性液晶層を配向（発色）させた。このとき、感光性液晶層は液晶相となり、中心波長４５０ｎｍの選択反射を示した（青色形成）。
続いて、８０℃で保持した状態で、前記感光性液晶層に対して、開口部が線幅８０μｍ、開口ピッチ２７０μｍのストライプ状のフォトマスクと、５３０ｎｍに透過中心波長を持つ干渉フィルタと、偏光板と、λ／４板（左円偏光）とを介してキセノン光（λ¹）を１０秒間照射（照射強度５ｍＷ／ｃｍ²）し、パターニングした。この時（８０℃）、感光性液晶層の光照射部は緑色の選択反射を示した。引き続き８０℃で保持した状態で、前記フォトマスクを線幅方向に９０μｍ移動させ、該フォトマスクと前記干渉フィルタとを介して上記同様に５秒間照射（λ¹；照射強度４０ｍＷ／ｃｍ²）し、パターニングした。すると、感光性液晶層の光照射部は赤色の選択反射を示した（８０℃）。尚、感光性液晶層の未照射部は青色の選択反射を示していた（配向工程）。以上より、感光性液晶層に青色(Ｂ)、緑色(Ｇ)、赤色(Ｒ)に選択反射を示すパターンを形成した。
【０１０８】
次いで、このガラス基板を６０℃のホットプレート上で保持し、窒素雰囲気のもと、３１３ｎｍに透過中心波長を持つ干渉フィルターを介して超高圧水銀灯により５秒間照射（λ²；照射強度１００ｍＷ／ｃｍ²）を行い、感光性液晶層の重合硬化を行った。更に、膜の硬化を促進する目的で２５０℃下で１５分間加熱処理し、本発明にかかるカラーフィルタを得た。
【０１０９】
得られたカラーフィルタのＢ、Ｇ及びＲの選択反射を示す中心波長は、それぞれ４４０ｎｍ、５３０ｎｍ及び６５０ｎｍであり、各色において色純度の高い色相が得られた。しかも、各色において、カラーフィルタ内での各画素間の選択反射の中心波長のバラツキは±２ｎｍ以内であり、色相の均一性の点でも優れていた。
【０１１０】
（実施例２）
実施例１と同様にして、フィルタ基板としての配向膜付ガラス基板を用意し、実施例１で用いた感光性液晶層用塗布液（１）に代えて、下記処方よりなる感光性液晶層用塗布液（２）を用いたこと以外、実施例１と同様にして、前記配向膜上に感光性液晶層を形成した（層形成工程）。層厚を共焦点顕微鏡により測定したところ、２．３μｍであった。
【０１１１】
【化１０】

【０１１２】
次いで、実施例１と同様に感光性液晶層が形成されたガラス基板を１００℃のホットプレート上に３分間保持し、感光性液晶層を配向（発色）させた。このとき、感光性液晶層は液晶相となり、中心波長４５５ｎｍの選択反射を示した（青色形成）。
続いて、８０℃で保持した状態で、前記感光性液晶層に対して、実施例１と同様（フォトマスク、５３０ｎｍに透過中心波長を持つ干渉フィルタ、偏光板、及びλ／４板（左円偏光）を介す）にしてキセノン光（λ¹）を２０秒間照射（照射強度５ｍＷ／ｃｍ²）した。この時（８０℃）、感光性液晶層の光照射部は緑色の選択反射を示した。引き続き８０℃で保持した状態で、実施例１と同様（フォトマスク及び干渉フィルタを介す）にして１０秒間照射（λ¹；照射強度４０ｍＷ／ｃｍ²）した。この時（８０℃）、感光性液晶層の光照射部は赤色の選択反射を示した。尚、感光性液晶層の未照射部は青色の選択反射を示していた（配向工程）。以上より、感光性液晶層に青色(Ｂ)、緑色(Ｇ)、赤色(Ｒ)に選択反射を示すパターンを形成した。
【０１１３】
次いで、実施例１と同様にして、超高圧水銀灯により５秒間照射（λ²）して感光性液晶層の重合硬化を行い、更に２５０℃下で１５分間加熱処理して、本発明にかかるカラーフィルタを得た。
得られたカラーフィルタのＢ、Ｇ及びＲの選択反射を示す中心波長は、それぞれ４４５ｎｍ、５３２ｎｍ及び６５５ｎｍであり、各色において色純度の高い色相が得られた。しかも、各色において、カラーフィルタ内での各画素間の選択反射の中心波長のバラツキは±２ｎｍ以内であり、色相の均一性の点でも優れていた。
【０１１４】
【発明の効果】
本発明によれば、簡便で良好な配向処理が可能で、照射ムラ等に起因する色相ズレに伴う色純度や解像度の低下を回避して、均一で色純度の高い色相（特に緑色若しくは赤色）が得られ、高精度に色分画（パターニング）を行い得る選択反射膜の製造方法を提供することができる。また、選択反射する色相及び色相均一性、特に緑色若しくは赤色の色相及びその均一性に優れ、高解像度で色分画（パターニング精度）に優れる画像特性、並びに良好な光学特性を備える選択反射膜を提供することができる。
【図面の簡単な説明】
【図１】 光反応型の液晶性組成物への照射光量と選択反射波長との関係を示す図である。
【図２】 基板上にコレステリック液晶層を形成するまでの工程を説明するための概略工程図である。
【図３】 基板上にコレステリック液晶層を形成するまでの工程を説明するための概略工程図である。
【図４】 本発明の選択反射膜の製造方法において、第一の態様によりＲＧＢ３色よりなる多色パターンを形成しているところを示す概略図である。
【図５】 本発明の選択反射膜の製造方法において、第二の態様により単色パターンを形成する工程を繰り返して画像様にＲＧＢ３色を形成しているところを説明するための概略工程図である。
【符号の説明】
４，４’ …フォトマスク
１０ …仮支持体
１２ …クッション層（熱可塑性樹脂層）
２４ …配向膜
１６ …コレステリック液晶層（相）
２０ …転写シート
２２ …基材（支持体）
２６ …カラーフィルタ用基板
２８ …マスク[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a selective reflection film, such as a color filter and a retardation film, which is suitably used for a display device such as an LCD, and a method for producing the same, and more specifically, obtained by light irradiation of a liquid crystalline composition exhibiting selective reflection. The present invention relates to a selective reflection film having high color reproducibility and display image quality, and a manufacturing method thereof.
[0002]
[Prior art]
For example, a color filter used in a color liquid crystal display or the like is generally composed of red (R), green (G), and blue (B) pixels and a black matrix for improving display contrast in the gaps. The
As a manufacturing method of such a color filter, in recent years, a manufacturing method capable of manufacturing a high-quality color filter with low material loss and high efficiency has been demanded. In recent years, a color filter mainly composed of a liquid crystalline material (particularly, cholesteric liquid crystal) has been widely studied because it is required to have high color purity.
[0003]
A color filter using a liquid crystalline composition mainly composed of cholesteric liquid crystal is a polarization-use color filter that reflects light of a certain wavelength and transmits the other light to display an image. High, excellent in transmittance and color purity.
In production, since a uniform thickness can be easily formed, a method of forming a film using a spin coating method or the like was general, but a material loss is large and disadvantageous in terms of cost. A production method using a photoreactive chiral compound is useful.
In other words, when a liquid crystalline composition containing a photoreactive chiral compound is used, when light with a sensitive wavelength of the chiral compound is irradiated in a pattern, the chiral compound is isomerized according to the intensity (irradiation amount) of the irradiation energy. As a result, the spiral pitch (helical twist angle) of the liquid crystal compound changes, so that the desired selective reflection color can be easily formed for each pixel only by pattern exposure with a difference in the amount of light, thereby reducing material loss. It is possible to achieve a reduction in the number of processes and cost reduction.
[0004]
However, the image characteristics required for color images in recent years are high. In particular, in color filters, in addition to high hue purity for selective reflection, high resolution is essential.
However, as described above, the selective reflection wavelength can be sequentially changed from the short wavelength to the long wavelength side (blue (B) → green (G) → red (R)) as the amount of irradiation light increases. As described above, the irradiation light quantity region a in which red selective reflection is obtained ¹ In contrast, the change in the wavelength from the short wavelength region to the vicinity of 570 nm with respect to the irradiation light amount is extremely steep compared to the irradiation light amount region a in which the green selective reflection can be obtained. ^Three Is very narrow, and when exposure unevenness occurs during irradiation, the color becomes yellowish or bluish green, and a high-purity green color as a primary color cannot be obtained, and the hue is not uniform. . Also, when red selective reflection is exhibited, if the absorption edge is shifted even a little, it tends to be orange or the visibility is lowered and the display becomes dark. In addition, in the case where RGB are arranged, the color fraction is blurred and the resolution is lowered at the boundary portion (pixel boundary portion) where the hues are adjacent to each other. As a result, the patterning accuracy is lowered.
[0005]
On the other hand, other optical films such as retardation films and circularly polarizing reflectors require a large intrinsic birefringence (Δn) from the viewpoint of obtaining good optical properties. Can increase Δn of the film, but is disadvantageous in terms of cost, and is required to be a thin film in terms of cost reduction.
[0006]
On the other hand, when a film (layer) containing a liquid crystalline composition (for example, a color filter film, a retardation film, etc.) is formed by coating, especially in the case of a low molecular liquid crystal, the liquid crystal molecules should be horizontal (to the substrate) on the substrate side. Even when the alignment treatment is performed, since one side of the color filter forming layer is at the air interface, the liquid crystal molecules stand vertically on the air interface side, and the tilt angle (pretilt angle) of the liquid crystal molecules continuously in the thickness direction of the layer. A changing state occurs. For this reason, it is usually necessary to sandwich both sides of the layer with an alignment film. However, when the liquid crystalline composition is used as an optical film by polymerization, at least one side alignment is performed after polymerization in order to reduce weight and thickness. There is also a problem that it is necessary to peel off the film, which involves an increase in steps such as installation and removal of the alignment film and an increase in waste materials.
[0007]
[Problems to be solved by the invention]
As described above, in a manufacturing method using a liquid crystalline material containing a photoreactive chiral compound, a good alignment treatment is simply performed, and the color purity (especially green or red) is reduced or the hue is not uniform due to color shift. Technology that can produce selective reflection films (color filters, phase difference films, circularly polarizing reflectors, etc.) with consistently high resolution, good color fractionation, and good image characteristics and optical characteristics is still established. The current situation is not.
[0008]
In view of the above, an object of the present invention is to solve the conventional problems and achieve the following object. That is,
The present invention enables simple and good alignment processing, avoids a decrease in color purity and resolution due to hue deviation caused by uneven irradiation during patterning, and avoids a decrease in color purity and resolution (particularly green or red). ) And a method for producing a selective reflection film capable of performing color fractionation (patterning) with high accuracy, and excellent selective hue and hue, particularly green or red hue and uniformity thereof. Another object of the present invention is to provide a selective reflection film having high resolution and excellent color characteristics (patterning accuracy) and image characteristics and good optical characteristics.
[0009]
[Means for Solving the Problems]
The inventors of the present invention have obtained the following knowledge regarding the image / optical characteristics of the selective reflection film (particularly, the color purity for selective reflection, improvement in hue uniformity, and higher resolution).
When producing a selective reflection film containing a photoreactive chiral compound, for example, a color filter using a photoreactive cholesteric liquid crystal composition, when pattern exposure is performed on the liquid crystalline composition (liquid crystal layer), regions having different amounts of transmitted light are formed. Patterning can be performed by a single exposure using a mask having a mask, but since a light quantity region capable of forming green (G) selective reflection is particularly narrow, it is difficult to always obtain a green hue with a constant chromaticity. In addition, red (R) that selectively reflects tends to have an orange taste or a decrease in visibility, resulting in a dark display if the absorption edge is shifted even a little. Furthermore, it is difficult to control the intermediate color from a short wavelength to around 570 nm in other applications such as printed matter and anti-counterfeit display.
[0010]
From the above knowledge, the above-mentioned problem is that circularly polarized light or elliptically polarized light in the same direction as the twist direction of the spiral of the liquid crystal is used for patterning the cholesteric liquid crystal composition, and the wavelength of the circularly polarized light or elliptically polarized light is changed to that of the photoreactive chiral compound. This is achieved based on setting the wavelength to be the same as or near to the absorption wavelength, and the specific means is as follows.
<1> A liquid crystalline composition comprising a liquid crystal compound having at least one polymerizable group (preferably a nematic liquid crystal compound), a photoreactive chiral compound having absorption isomerizable in the visible light region, and a polymerization initiator. Light like an image (wavelength λ ¹ ) A method of manufacturing a selective reflection film that irradiates and forms a pattern showing selective reflection according to the irradiation, wherein the light irradiation is performed by either circularly polarized light or elliptically polarized light in the same direction as the twisted direction of the spiral of the liquid crystal. It is a manufacturing method of the selective reflection film characterized by using.
[0011]
<2> The liquid crystal composition has a wavelength λ ¹ The liquid crystal composition is irradiated with the light to form an exposure dose distribution, and a selective reflection according to the exposure dose distribution is obtained. Then, the liquid crystal composition in this state has a wavelength λ. ² A step of polymerizing and curing an image to form a multicolor pattern, the wavelength λ ¹ Is the method for producing a selective reflection film according to <1>, wherein the light is any one of circularly polarized light and elliptically polarized light in the same direction as the twist direction of the spiral of the liquid crystal.
[0012]
<3> The liquid crystal composition has a wavelength λ ¹ After irradiating the image of light in an image-like manner and showing selective reflection according to the irradiation, the region λ is further wavelength λ ² At least one step of forming a monochromatic pattern by irradiating the light of ¹ Is the method for producing a selective reflection film according to <1>, wherein the light is any one of circularly polarized light and elliptically polarized light in the same direction as the twist direction of the spiral of the liquid crystal.
<4> Wavelength λ ¹ The method for producing a selective reflection film according to <3>, wherein a multicolor pattern consisting of n colors is formed by repeating the step of forming a monochromatic pattern n times by changing the irradiation amount of the light in n steps. is there.
[0013]
<5> A liquid crystal composition in a state showing selective reflection of the first color in advance has a wavelength λ ² After forming a monochromatic pattern by image-wise polymerization and curing, a wavelength λ so as to show selective reflection at a wavelength different from that of the first color. ¹ In the above <3>, the step of forming a single color pattern is repeated (n−1) times by changing the amount of irradiation of the light in (n−1) stages to form a multicolor pattern consisting of n colors. This is a method for producing the selective reflection film.
[0014]
<6> The photoreactive chiral compound has an isomerizable absorption in a wavelength region of 490 to 570 nm or 630 to 690 nm, and has a wavelength λ ¹ Is a method for producing a selective reflection film according to any one of <1> to <5>, wherein the light is light having a wavelength of 490 to 570 nm or 630 to 690 nm.
<7> With respect to the absorption wavelength λ (nm) capable of isomerization of the photoreactive chiral compound, the wavelength λ ¹ (nm) is (λ-50) ≦ λ ¹ The method for producing a selective reflection film according to any one of <1> to <6>, wherein ≦ (λ + 50) is satisfied.
<8> The method for producing a selective reflection film according to any one of <1> to <7>, wherein the liquid crystalline composition contains an air interface alignment agent.
<9> A selective reflection film obtained by the method for producing a selective reflection film according to any one of <1> to <8>.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, either circularly polarized light or elliptically polarized light in the same direction as the twist direction of the spiral of the liquid crystal (wavelength λ ¹ ), Preferably the wavelength λ ¹ (Λ−50) ≦ λ ¹ ≦ (λ + 50) [λ: absorption wavelength (nm) capable of isomerization of photoreactive chiral compound].
Hereinafter, the selective reflection film of the present invention and the manufacturing method thereof will be described in detail.
[0016]
<Method for producing selective reflection film>
The method for producing a selective reflection film of the present invention has a twist direction of a liquid crystal spiral with respect to a liquid crystal composition capable of exhibiting selective reflection (hereinafter also referred to as “cholesteric liquid crystal composition” or “cholesteric liquid crystal layer”). Circularly polarized light or elliptically polarized light in the same direction is irradiated like an image, and a pattern showing selective reflection according to the irradiation (amount) is formed (hereinafter, this operation may be collectively referred to as “exposure process”). Here, “the twist direction of the spiral of the liquid crystal” refers to the direction (right circle / left circle) in which the structure in which the liquid crystal molecules are arranged in a spiral is twisted.
[0017]
That is, in the exposure process, light (wavelength λ) is applied to all or a part including a desired region to be colored. ¹ Irradiation (patterning) of the circularly or elliptically polarized light of (1) causes a photoreactive chiral compound to react with the light, and the helical pitch of the liquid crystal changes due to structural changes due to trans-cis isomerization or chemical reaction, thereby allowing the desired selection. A state showing reflection, that is, a desired hue is exhibited. And preferably further light (wavelength λ ² (≠ λ ¹ )) Irradiated, only the desired region can be polymerized and cured to fix the helical pitch of the liquid crystal.
In the present invention, light having a uniform and high color purity (particularly green or red) is particularly effectively obtained, and light that is close to circularly polarized light (substantially circular) in that highly accurate color fractionation (patterning) is possible. (Polarized light) is preferable, and an embodiment in which image irradiation is performed with circularly polarized light is particularly preferable.
[0018]
Further, since circularly polarized light or elliptically polarized light in the same direction as the twisted direction of the liquid crystal is used, for example, 490 nm ≦ λ ¹ When patterning with green light of ≦ 570 nm, the hue that is selectively reflected with irradiation changes from blue to green, and most of the irradiation light is reflected and the twisting change is difficult to proceed. It is possible to cause a torsional change that can ensure the productivity while expanding the light amount range in which reflection can be obtained.
[0019]
The method for producing a selective reflection film according to the first aspect of the present invention has a wavelength λ with respect to a liquid crystalline composition capable of exhibiting selective reflection. ¹ Is irradiated with circularly polarized light or elliptically polarized light (in the same direction as the twist direction of the spiral of the liquid crystal) to form an exposure amount distribution, and a state showing selective reflection according to the exposure amount distribution is obtained. Further wavelength λ ² Can be suitably carried out by including a step (exposure step) in which a multicolor pattern is formed by irradiating the above-mentioned light and polymerizing and curing in an image-like manner.
[0020]
Therefore, the liquid crystalline composition (preferably showing a non-liquid crystal state) is subjected to the above exposure step once, for example, through a mask having regions with different amounts of transmitted light. An exposure amount distribution can be formed at once on the entire desired region of the cholesteric liquid crystal layer), and a color filter exhibiting selective reflection of a plurality of colors can be easily obtained. The wavelength λ ¹ The light irradiation may be performed on an arbitrary region of the liquid crystal layer, and may be performed on the entire surface, or may be performed only on a portion including a desired target region to be colored.
Even in the case of this aspect, a uniform hue with high color purity (particularly green or red) can be obtained, and color fractionation (patterning) can be performed with high accuracy. Λ ² As a result, it is possible to prevent diffusion of chiral compounds isomerized with different amounts of light between adjacent areas (colored pixels) during irradiation of light, resulting in hue blurring at pixel boundaries, etc. The resulting decrease in color purity and resolution can also be effectively prevented.
[0021]
As a specific configuration aspect of this embodiment, the liquid crystalline composition contains λ ¹ A step of forming an exposure amount distribution in the liquid crystalline composition by irradiating the light, and raising the temperature of the liquid crystalline composition on which the exposure amount distribution is formed (preferably, transitioning from a non-liquid crystal state to a liquid crystal state) ), Forming a state (region) for selective reflection according to the exposure amount distribution, and λ in the liquid crystalline composition in which the state is formed ² (≠ λ ¹ And the step of irradiating and curing by polymerization or crosslinking.
[0022]
The method for producing a selective reflection film according to the second aspect of the present invention has a wavelength λ with respect to a liquid crystalline composition (preferably showing a non-liquid crystal state) capable of exhibiting selective reflection. ¹ A state in which a single-color selective reflection corresponding to the irradiation is performed by irradiating circularly polarized light or elliptically polarized light (in the same direction as the twisted direction of the spiral of the liquid crystal) (preferably, the temperature is raised to shift from the non-liquid crystal state to the liquid crystal state) Then, the wavelength λ is further added to the state region. ² Can be suitably implemented by including at least one step (exposure step) of forming a single-color pattern by irradiating the above light and polymerizing and curing in an image-like manner. Here, “a state exhibiting selective reflection of a single color” means that an area that has not yet been polymerized and cured has a wavelength λ. ¹ A state in which a desired single color is exhibited by the irradiation of light.
[0023]
Therefore, in this aspect, a pattern showing selective reflection of a single color can be formed by passing the exposure process once, and a color filter showing selective reflection of a plurality of colors can be obtained by repeating this process multiple times. Can do.
Wavelength λ ¹ The light irradiation may be performed on an arbitrary region of the cholesteric liquid crystal layer, may be performed on the entire surface of the cholesteric liquid crystal layer, or may be performed only on a portion including a desired target region to be colored, or in an image-like manner. From the viewpoint of simplifying the process without any manufacturing restrictions, it is preferable to perform the irradiation without limiting the irradiation region.
[0024]
In the first and second embodiments of the present invention, both of the wavelengths λ ¹ Wavelength λ after light irradiation ² By fixing the orientation of the liquid crystal molecules by irradiating the light, the selective reflection wavelength is kept unchanged and is imaged (patterned). ² The light irradiation is performed in such a manner that it can be polymerized and cured like an image by irradiation. Therefore, λ ² It is not necessary to irradiate the light in an image-like manner. For example, if it is sufficient to form the last hue formation (formation of the third color in the case of RGB three colors) over the entire non-fixed region, the entire surface is irradiated. The final pattern is formed by polymerization and curing in an image-like manner by irradiation with the entire surface.
[0025]
In the second aspect, it is sufficient that at least one exposure step is included, and specifically, it may be any one of the following aspects A and B, and among the second aspects, The selective reflection film can be particularly suitably produced by the two aspects. Here, a cholesteric liquid crystal color filter will be described as an example of the selective reflection film.
[0026]
In the aspect A according to the second aspect, the exposure process includes at least one step, and the wavelength λ ¹ The step of forming a monochromatic pattern (that is, the exposure step) is repeated n times by changing the irradiation amount of circularly polarized light or elliptically polarized light (in the same direction as the direction of twist of the liquid crystal spiral) in the visible light region. Thus, a multicolor pattern consisting of n colors can be formed. In the above, changing the light irradiation amount in n steps does not necessarily indicate that the irradiation amount changes in order, but in each step of the exposure process performed n times, the light irradiation amount is changed to a desired selective reflection. As shown, all the doses are different.
[0027]
In this aspect, for example, when producing a color filter (n = 3) composed of three colors of R (red), G (green), and B (blue), the liquid crystalline composition (cholesteric liquid crystal layer) In order to obtain a selective reflection wavelength indicating the hue (for example, R) of the first color, the wavelength λ ¹ Circularly polarized light or elliptically polarized light (preferably light having a wavelength of 490 to 570 nm or 630 to 690 nm) (irradiation amount h) ^α Irradiate in (stage 1), then wavelength λ ² After forming a first color pattern (for example, R pixel) by irradiating light (less than 400 nm) like a desired image, a selective reflection wavelength indicating a hue (for example, G) of the second color is obtained. Wavelength λ ¹ Of circularly polarized light or elliptically polarized light ^β Irradiate in (stage 2), then wavelength λ ² In order to obtain a selective reflection wavelength indicating the hue of the third color (for example, B) by forming the second color pattern (for example, G pixel) by irradiating the light of ¹ Of circularly polarized light or elliptically polarized light ^γ Irradiate in (step 3), then wavelength λ ² The pattern of the third color (e.g., B pixel) is formed by irradiating the light (if desired, as desired). In this aspect, the non-uniformity of the spiral structure (pitch) of the liquid crystal due to irradiation unevenness or the like can be eliminated, and a sharp and high-resolution cholesteric liquid crystal color filter with high color purity and hue uniformity can be produced.
[0028]
In the aspect B according to the second aspect, the wavelength λ is applied to the cholesteric liquid crystal layer (liquid crystalline composition) that is in a state of selective reflection of the first color in advance. ² After irradiation with light (less than 400 nm) to form a single color pattern by polymerization and curing in an image-like manner, the wavelength λ is further selected so as to exhibit selective reflection at a wavelength different from that of the first color. ¹ The step of forming a monochromatic pattern by changing the irradiation amount of circularly polarized light or elliptically polarized light (in the visible light region) (in the same direction as the twist direction of the spiral of the liquid crystal) in (n-1) steps (ie, exposure step) By repeating (n-1) times, a multicolor pattern composed of n colors can be formed. Similarly to the aspect A, changing the light irradiation amount to the (n−1) stage does not necessarily indicate that the irradiation amount changes in order, but each step of the exposure process performed (n−1) times. In this case, the light irradiation amounts are all different from each other so as to exhibit desired selective reflection.
[0029]
In this aspect, before shifting to the exposure step, the liquid crystalline composition is formed in a state showing a predetermined selective reflection color (first color selective reflection) in advance. As a result, the number of processes can be further reduced, and the first color with better color purity and hue uniformity can be easily formed in the wavelength region where the amount of irradiation changes sharply with respect to the amount of irradiation light, and the cost can be reduced. Can also be planned.
As a method for setting a predetermined selective reflection color (selective reflection of the first color) in advance, for example, (1) a cholesteric liquid crystal layer is provided on the surface of the alignment film, and the wavelength λ ² (2) Transfer the cholesteric liquid crystal layer using the transfer material (the following mode (1)) or apply and form the cholesteric liquid crystal layer (the following mode (2)) The amount of light h at which the liquid crystal layer can exhibit the selected wavelength of the first color on the entire surface or a part including the region to be obtained ^α Circularly or elliptically polarized light (wavelength λ ¹ ).
[0030]
For example, in the case of a cholesteric liquid crystal color filter (n = 3) composed of three colors of RGB, the wavelength λ is already in a state showing selective reflection of the first color (for example, R). ² After forming a first color pattern (for example, R pixel) by irradiating light (less than 400 nm) like a desired image, a selective reflection wavelength indicating a hue (for example, G) of the second color is obtained. Wavelength λ ¹ Circularly polarized light or elliptically polarized light (preferably light having a wavelength of 490 to 570 nm or 630 to 690 nm) (irradiation amount h) ^β Irradiate in (stage 1), then wavelength λ ² In order to obtain a selective reflection wavelength indicating the hue of the third color (for example, B) by forming the second color pattern (for example, G pixel) by irradiating the light of ¹ Of circularly polarized light or elliptically polarized light ^γ Irradiate in (stage 2), then wavelength λ ² The pattern of the third color (e.g., B pixel) is formed by irradiating the light (if desired, as desired). Also in this aspect, the non-uniformity of the spiral structure (pitch) of the liquid crystal due to irradiation unevenness or the like can be eliminated, and a sharp and high-resolution cholesteric liquid crystal color filter with high color purity and hue uniformity can be produced.
[0031]
<Exposure process>
In the exposure process according to the present invention, hue adjustment (color generation by selective reflection) that brings the liquid crystalline composition (cholesteric liquid crystal layer) into a desired selective reflection state, and patterning and selective reflection by polymerization curing of the cholesteric liquid crystal layer. Both of wavelength fixation are performed by light irradiation. That is, after the photo-reactive chiral compound is sensitive to the visible light region (preferably in the wavelength region of 400 nm or more), the polymerization initiator is sensitive to high sensitivity. Possible wavelength λ ² It is cured by photopolymerization with light (less than 400 nm), and the helical structure of the liquid crystal compound is fixed to a desired selective reflection color.
[0032]
More specific description will be given below. First, wavelength λ ¹ When the cholesteric liquid crystal layer is irradiated with the circularly polarized light or elliptically polarized light, the photoreactive chiral compound coexists and the helical structure of the nematic liquid crystal compound changes depending on the illuminance. Indicates color. Therefore, a desired hue can be obtained by changing the irradiation amount for each desired region. ² And is cured (fixed) to be patterned to obtain a monochromatic image (exposure process). In the first aspect, a multicolor liquid crystal color filter can be produced by a single exposure process. In the second aspect, the exposure process is repeated.
[0033]
In the present invention, the wavelength λ ¹ As the light in the (visible light region), circularly polarized light or elliptically polarized light in the same direction as the twist direction of the spiral of the liquid crystal is used. For example, 490 nm ≦ λ ¹ In the case of patterning with green light of ≦ 570 nm, as described above, the hue selectively reflected according to the amount of irradiation shows from blue to green, and most of the irradiation light is reflected, but shows the selective reflection. Polarized light that travels circularly in the same direction as the twist direction of the spiral structure of the liquid crystal composition easily penetrates into the liquid crystal composition, maintains a twist change due to irradiation, and exhibits a red selective reflection pitch (twist angle). ) Can continue to change.
[0034]
Further, the wavelength λ ¹ As the wavelength of the light, it is possible to set the wavelength close to the photosensitive peak wavelength belonging to the photosensitive wavelength range of the photoreactive chiral compound, in particular, the visible light range (preferably the wavelength range of 400 nm or more). Although it is preferable at the point obtained, in this invention, it is especially preferable to use the light of 490-570 nm or 630-690 nm from a viewpoint of ensuring green or red color purity, hue uniformity, etc. especially.
Specifically, (1) a wavelength λ is added to a photoreactive chiral compound having absorption capable of isomerization at a wavelength of 490 to 570 nm. ¹ Is combined with light having a wavelength of 490 to 570 nm, and (2) the wavelength λ is applied to a photoreactive chiral compound having an absorption isomerizable at wavelengths of 630 to 690 nm. ¹ A mode in which light of 630 to 690 nm is combined is suitable.
[0035]
Furthermore, the wavelength λ of the patterning light is compared to the isomerizable absorption wavelength λ (nm) of the photoreactive chiral compound. ¹ (nm) is (λ-50) ≦ λ ¹ It is particularly preferable that ≦ (λ + 50) is satisfied. Above all, (λ−30) ≦ λ ¹ ≦ (λ + 30) is most preferable.
[0036]
Since the visible light region includes wavelengths exhibiting blue (B) to green (G) to red (R), a chiral compound having light absorption in a desired wavelength region within the above range can be used. As shown in FIG. 1, a light amount region a corresponding to a region where the selective reflection wavelength changes sharply with respect to the irradiation light amount. ² For example, when combined as in the above (1), the light quantity region a indicating the selective reflection of green ^Three Therefore, a desired hue can be stably and uniformly obtained without being affected by a slight change in the amount of light (irradiation unevenness or the like). As a result, it is possible to eliminate the non-uniformity of the spiral change of the liquid crystal due to the light amount change due to the unevenness of irradiation and the like, and it is possible to prevent the hue purity and uniformity from being lowered. FIG. 1 shows the relationship between the amount of light applied to the photoreactive liquid crystalline composition and the selective reflection wavelength.
In addition, since the photosensitivity peak wavelength of the polymerization initiator used in combination is generally in the vicinity of 400 nm, as described later, it is possible to effectively prevent hue deviation in the process of fixing the helical structure after patterning.
[0037]
The wavelength λ ² The wavelength of the light is preferably set to a photosensitive wavelength region of the polymerization initiator, particularly a wavelength close to the photosensitive peak wavelength, from the viewpoint of obtaining sufficient photopolymerization sensitivity.
Wavelength λ ¹ And λ ² There is no restriction | limiting in particular in the irradiation amount of light, and illumination intensity (irradiation intensity | strength), According to the material to be used so that photosensitivity can fully be obtained, it can select suitably.
[0038]
The wavelength λ ¹ As a method of obtaining circularly polarized light or elliptically polarized light, for example, a method using a polarizing plate, a quarter wavelength plate (λ / 4 plate), a method of combining a linear polarizer and a λ / 4 wavelength plate, etc. As the light source used for the irradiation, a light source that emits visible light (preferably 400 nm or more) is preferable in that it has high energy and can rapidly change the structure of the liquid crystal compound and the polymerization reaction. For example, a xenon lamp or the like However, a light source that emits the following ultraviolet rays through the polarizing plate or the λ / 4 plate may be used. Moreover, it is preferable to have a light quantity variable function.
The wavelength λ ² As the light source used for the irradiation of light, a light source that emits ultraviolet rays is preferable in that it has high energy and the structure change and polymerization reaction of the liquid crystal compound can be performed quickly. For example, a high-pressure mercury lamp, metal halide lamp, Hg-Xe lamp, etc. Is mentioned. Moreover, it is preferable to have a light quantity variable function.
[0039]
The mask used for light irradiation can be appropriately selected from known masks such as those provided with openings in a pattern and those having a light transmittance determined in a pattern. In the first aspect, the mask can be appropriately selected from known masks such as those having openings in a pattern and those having a light transmittance determined in a pattern.
[0040]
Further, in the method for producing a selective reflection film of the present invention, in addition to the exposure step, a step of appropriately subjecting the contact surface with the cholesteric liquid crystal layer to an orientation treatment (orientation treatment step) according to the target product and the production mode to be selected. ), A process of transferring the liquid crystal layer by adhesion (laminating) and peeling with a transfer material having a liquid crystal layer (transfer process), a process of forming a liquid crystal layer by applying a cholesteric liquid crystal phase (application process), etc. May be.
[0041]
Taking the case of producing a color filter as an example, for example, the production method of the following aspect (1) or (2) may be used, and it can be more suitably produced by these two aspects.
<Aspect (1)>
(Step 1): A step of producing a transfer material.
A coating liquid crystal composition (cholesteric liquid crystal composition) is provided on a temporary support, and a transfer material having at least a cholesteric liquid crystal layer made of the composition is formed.
The coating liquid crystalline composition can be prepared by dissolving and dispersing each component in a suitable solvent. Examples of the solvent include 2-butanone, cyclohexanone, methylene chloride, chloroform and the like.
A cushion layer containing a thermoplastic resin or the like may be provided between the liquid crystal layer and the temporary support from the viewpoint of ensuring adhesion during transfer, such as when there is a foreign matter on the transfer target. It is also preferable to subject the surface of the cushion layer or the like to an orientation treatment such as a rubbing treatment [orientation treatment step].
[0042]
(Step 2): Layer forming step of transferring and forming a cholesteric liquid crystal layer.
The transfer material is laminated on a light-transmitting base material (substrate), and the transfer material is peeled from the substrate to form a cholesteric liquid crystal layer (transfer process).
In addition to the light-transmitting substrate, an image receiving material having an image receiving layer on the substrate may be used. Although a liquid crystal layer may be formed by coating as in the mode (2) described later, a transfer method is preferred in terms of material loss and cost. The liquid crystal layer may be composed of a plurality of layers by further laminating after the following (Step 3).
(Step 3): The exposure step according to the present invention described above.
For the cholesteric liquid crystal layer on the substrate, the wavelength λ ¹ A region showing selective reflection of a single color is formed by irradiating the light of ² Is cured and fixed to a desired selective reflection wavelength and pattern.
In addition, about each process and materials, such as a transcription | transfer material and a base material to be used, each specification of Japanese Patent Application No. 11-342896 and Japanese Patent Application No. 11-343665 previously submitted by the present inventors is described in detail. Are listed.
[0043]
<Aspect (2)>
(Step 1): Layer forming step of applying and forming a cholesteric liquid crystal layer.
A cholesteric liquid crystal layer is formed by directly coating a liquid crystalline composition on a substrate (support) constituting a color filter. The liquid crystal layer can be formed by coating a liquid crystal composition prepared in a coating liquid as described above by a known coating method using a bar coater or a spin coater. Further, an alignment film similar to the above may be formed between the cholesteric liquid crystal layer and the substrate. It is also preferable to subject the surface of the alignment film or the like to an alignment treatment such as a rubbing treatment [alignment treatment step].
(Step 2): The same exposure step as in (Step 3) of the aspect (1).
[0044]
Hereinafter, as an example of a method for producing a selective reflection film of the present invention, a method for producing a cholesteric liquid crystal color filter according to the above-described aspect B will be described with reference to FIGS. 2 and 3 are schematic process diagrams for explaining a process until a cholesteric liquid crystal layer is formed on a substrate. FIG. 4 is a schematic process diagram for explaining that a multicolor pattern composed of three colors of RGB is formed according to the first embodiment. FIG. 5 is a schematic process diagram for explaining that RGB color is formed like an image by repeating the process of forming a single color pattern according to the second embodiment.
[0045]
First, each component described later is dissolved in an appropriate solvent to prepare a coating cholesteric liquid crystal composition.
As shown in FIG. 2A, a temporary support 10 is prepared, and a cushion layer (thermoplastic resin layer) 12 is provided on the temporary support 10 by applying, for example, acrylic resin, polyester, polyurethane, or the like. . Furthermore, an alignment film made of polyvinyl alcohol or the like may be laminated, and the alignment film is subjected to a rubbing process as necessary (alignment processing step). The orientation can be improved by rubbing treatment.
Next, as shown in FIG. 2B, a coating cholesteric liquid crystal composition is applied on the cushion layer 12 and dried to form a cholesteric liquid crystal layer 16, and then a cover is formed on the cholesteric liquid crystal layer 16. A film 18 is provided to produce a transfer material. Hereinafter, the transfer material is referred to as a transfer sheet 20.
[0046]
On the other hand, as shown in FIG. 2- (C), another base material 22 is prepared, an alignment film 24 is formed on the base material 22 in the same manner as described above, and a rubbing process is performed on the surface (alignment process). Process). Hereinafter, this is referred to as a color filter substrate 26.
Subsequently, after the cover film 18 of the transfer sheet 20 is peeled off, as shown in FIG. 3D, the surface of the cholesteric liquid crystal layer 16 of the transfer sheet 20 and the surface of the alignment film 24 of the color filter substrate 26. Are laminated so that they come into contact with each other and laminated through a roll rotating in the direction of the arrow in the figure. Thereafter, as shown in FIG. 3- (E), peeling is performed between the cushion layer 12 of the transfer sheet 20 and the cholesteric liquid crystal layer 16, and the cholesteric liquid crystal layer is transferred onto the color filter substrate (transfer process). In this case, the cushion layer 12 does not necessarily have to be peeled off together with the temporary support 10.
[0047]
Here, the cholesteric liquid crystal layer may be in a state in which the cholesteric liquid crystal layer shows a selective reflection of the first color in advance (the above-described aspect B). ¹ The first step after the transfer step can be shifted to patterning of the first color and fixing of the hue as shown in FIG. 5- (Fa). Separately from the transfer process, the wavelength λ ¹ May be passed through a process of irradiating with the light of 1 to display a single color selective reflection (Aspect A).
[0048]
After the transfer, RGB three colors can be formed like an image as follows. That is,
As shown in FIG. 4-(F-i), an exposure mask 28 having a plurality of regions having different light transmittances is disposed in close contact with the cholesteric liquid crystal layer 16, and the wavelength λ passes through the mask 28. ¹ The cholesteric liquid crystal layer 16 may be irradiated in a pattern (first aspect). After irradiation, it is heated to a temperature at which a liquid crystal state showing a selective reflection wavelength can be formed corresponding to the photoreactive chiral compound isomerized according to the amount of light irradiation. Then, as shown in FIG. 4- (F-ii), the wavelength λ with respect to the cholesteric liquid crystal layer 16. ² Is fixed by irradiating light (ultraviolet light or the like), and a reflection region of BGR is formed as shown in FIG. 4- (F-iii).
[0049]
Moreover, you may irradiate as shown in FIG. That is, the wavelength λ is applied to the cholesteric liquid crystal layer 16 already in the state of selective reflection of the first color (for example, R) through the photomask 4. ² Is irradiated like an image, only the irradiated region is cured, and the hue of the first color is fixed (for example, R pixel) and patterned (see FIG. 5- (Fb)). . Subsequently, as shown in FIG. 5- (F-b), the light amount h ^β Light (wavelength λ ¹ ) Is irradiated on the entire surface, a state of selective reflection of the second color is formed in the entire area where the cholesteric liquid crystal layer is not fixed. In this state, a photomask 4 ′ is arranged as shown in FIG. 5- (Fc), and the wavelength λ is passed through the photomask 4 ′. ² Is irradiated like an image, only the irradiated region is cured and the hue of the second color is fixed (for example, G pixel) and patterned (see FIG. 5- (Fd)). . Further, as shown in FIG. ^γ Light (wavelength λ ¹ ) Is irradiated on the entire surface, a state showing selective reflection of the third color is formed in the entire area where the cholesteric liquid crystal layer is not fixed. Here, in the case of manufacturing a color filter composed of three colors of RGB, it is not necessary to selectively pattern the fixation of the hue of the third color and the formation of a selective reflection region (for example, B pixel). As shown in FIG. 5- (F-e), the wavelength λ ² Is sufficient to irradiate the entire surface. Note that the wavelength λ of the light irradiated in each exposure step ¹ Are not necessarily the same wavelength.
[0050]
Further, if necessary, unnecessary portions on the cholesteric liquid crystal layer 16 (for example, remaining portions such as cushion layers and intermediate layers, unexposed portions) are removed by alkali development using 2-butanone, chloroform, or the like. The
As described above, the cholesteric liquid crystal color filter of the present invention composed of three colors of RGB can be produced.
[0051]
The method shown in FIGS. 2 to 5 is an embodiment of a manufacturing method using a laminate method, but may be a manufacturing method using a coating method in which a liquid crystal layer is directly formed on a color filter substrate. In this case, when applied to the above embodiment, first, a cholesteric liquid crystal layer is applied on the alignment film 24 of the color filter substrate 26 shown in FIG. ) To (F-iii) or the processes shown in FIG. 5 (Fa) to (Fe) are sequentially performed.
[0052]
The thickness of the liquid crystal layer (sheet-like liquid crystal composition) that functions as a cholesteric liquid crystal color filter is preferably 0.5 to 4 μm.
In addition, the selective reflection film (for example, a color filter) manufactured by the manufacturing method of the present invention is composed of a liquid crystal composition (cholesteric liquid crystal layer) provided on a base material, or a liquid crystal composition only. Any of those may be used.
[0053]
As described above, a liquid crystalline composition containing a photoreactive chiral compound having absorption isomerizable in the visible light region, preferably 490 to 570 nm or 630 to 690 nm, and light in the vicinity of the absorption wavelength of the chiral compound is used. Irradiates the image like an image, so it is possible to eliminate the non-uniformity of the spiral change (twisting change rate) of the liquid crystal due to the light amount change due to uneven irradiation, etc. without being affected by the slight change in the light amount, and the hue purity and hue uniformity A decrease can be prevented. As a result, a desired hue (especially green or red) can be stably and uniformly obtained.
[0054]
<Liquid crystal composition>
The liquid crystal composition (cholesteric liquid crystal composition) according to the present invention includes a liquid crystal compound having at least one polymerizable group, a photoreactive chiral compound having absorption isomerizable in the visible light region, and a polymerization initiator. At least, preferably an air interface alignment agent and a polymerizable monomer, and may contain other components such as a binder resin and a polymerization inhibitor as required.
[0055]
-Photoreactive chiral compounds-
The photoreactive chiral compound (hereinafter sometimes simply referred to as “chiral compound”) has a photosensitivity peak wavelength longer than the photosensitivity peak wavelength of the polymerization initiator described later in that patterning sensitivity can be improved. What exists in the wavelength side is preferable, and in this invention, the photoreactive chiral compound which has the light absorption which can be photoisomerized in visible light region (preferably 400 nm or more) is contained.
[0056]
Since the region includes wavelengths exhibiting blue (B) to green (G) to red (R), by selecting a chiral compound having light absorption in a desired wavelength region corresponding to the light source wavelength used, As shown in FIG. 1, a light amount region a corresponding to a region where the change in selective reflection wavelength is particularly steep with respect to the irradiation light amount. ² For example, a light quantity region a indicating selective reflection of green ^Three Therefore, a desired hue (for example, green) can be stably obtained without being affected by a slight change in light amount (irradiation unevenness or the like). As a result, it is possible to eliminate the non-uniformity of the spiral change of the liquid crystal accompanying the change in the amount of light due to irradiation unevenness and the like, and it is possible to prevent the decrease in hue purity and hue uniformity.
[0057]
The photoreactive chiral compound is a compound that can change the helical pitch induced in the liquid crystalline composition by light irradiation (visible light). For this reason, as a necessary site (molecular structural unit), the chiral site and light irradiation. And a site that causes a structural change. These sites are preferably contained in one molecule.
In the present invention, in addition to the photoreactive chiral compound, a chiral compound that does not photoreact, such as a chiral compound having a large twist-dependent temperature dependence, may be used in combination.
[0058]
In the present invention, it is more preferable to use a compound having isomerizable light absorption at 490 to 570 nm or 630 to 690 nm among compounds having light absorption capable of photoisomerization in the visible light region.
When the isomerizable light absorption is in the range of 490 to 570 nm, the wavelength region corresponds to the selective reflection wavelength showing green, but the liquid crystalline composition accompanying the isomerization of the chiral compound as the light in the wavelength region is irradiated. The helical pitch (twisting angle) of the film shows selective reflection from blue to green. At this time, most of the irradiation light is reflected and the amount of light absorbed by the liquid crystalline composition can be reduced. As a result, since isomerization occurs slowly, the light quantity range for obtaining green selective reflection can be expanded, and the non-uniformity of the spiral change of the liquid crystal accompanying the light quantity change due to irradiation unevenness or the like can be eliminated. That is, green color purity and hue uniformity are improved, and pattern position accuracy (color fractionation) can also be improved.
[0059]
On the other hand, when red is selectively reflected, the red end tends to have an orange color or the visibility is lowered and the display is darkened if the absorption edge is slightly shifted. The wavelength range of 630 to 690 nm coincides with the selective reflection wavelength indicating red. However, when a chiral compound having an isomerizable light absorption of 630 to 690 nm is used, irradiation with light in the wavelength range causes red light emission. Color purity is improved, and pattern position accuracy (color fractionation) can also be improved.
[0060]
In addition, the photoreactive chiral compound preferably has a large force for inducing the helical structure of the liquid crystalline composition. For this purpose, the chiral site is located at the center of the molecule and the periphery thereof is made a rigid structure. The molecular weight is preferably 300 or more. In order to increase the inductive force of the helical structure by light irradiation, it is preferable to use a material having a large degree of structural change by light irradiation, and to bring the chiral part close to the part that causes the structural change by light irradiation.
Furthermore, a photoreactive chiral compound having high solubility in a liquid crystalline compound is preferable, and a compound whose solubility parameter SP value approximates that of a liquid crystalline polymerizable monomer is more preferable. Moreover, when the structure of the chiral compound is a structure in which one or more polymerizable bonding groups are introduced, the heat resistance of the formed liquid crystal composition film (color filter) can be improved.
Examples of the structure of the photoreactive moiety that undergoes a structural change upon irradiation with light include photochromic compounds (Satoshi Uchida, Masahiro Irie, Chemical Industry, vol. 64, p. 640, 1999, Atsushi Uchida, Masahiro Irie, Fine Chemicals, vol. 28 (9), p.15, 1999) and the like.
[0061]
The photoreactive chiral compound has at least one absorption wavelength that can be isomerized by light in the visible light region, preferably longer than 400 nm, and a compound having two or more absorption wavelengths is also suitable.
Specific examples will be shown below, but the present invention is not limited thereto.
[0062]
[Chemical 1]

[0063]
In the above structural formula, m represents an integer of 1 to 8, and an integer of 1 to 3 is preferable. Moreover, n represents the integer of 1-10 and the integer of 1-5 is preferable.
[0064]
In the present invention, two or more kinds of photoreactive chiral compounds having absorption isomerizable in the visible light region may be used in combination, or one kind may be used alone. In addition to the photoreactive chiral compound, a known photoreactive chiral compound or a non-photoreactive chiral compound may be used in combination.
[0065]
The content of the photoreactive chiral compound having absorption that can be isomerized in the visible light region is such that the photoreactive chiral compound is uniformly dissolved in “a liquid crystalline compound having at least one polymerizable group” and then heated. Preferably, the amount is not more than an amount at which the center wavelength of the selective reflection wavelength is 400 nm, which is calculated based on the selective reflection wavelength observed and measured at a temperature indicating the liquid crystal state. If this amount is exceeded, alignment degradation and sensitivity reduction may occur.
Further, the amount of the photoreactive chiral compound that is obtained by multiplying the HTP difference (ΔHTP) before and after the light irradiation of the twisting force changed by the light irradiation by the weight percentage thereof is preferably 1.07 or more. If the amount is less than this amount, it may be difficult to perform multicolor patterning with a wide hue width (that is, a wide wavelength region for selective reflection). Here, HTP refers to the helical pitch of the liquid crystal that changes due to light irradiation, that is, the twisting force (helical twisting power) of the helical structure, and the difference (ΔHTP) changes before and after light irradiation due to light irradiation. The difference in spiral pitch.
[0066]
-Liquid crystalline compound having at least one polymerizable group-
The liquid crystal compound having at least one polymerizable group (in the present specification, simply referred to as “liquid crystal compound”) can be appropriately selected from known liquid crystal compounds having a polymerizable group, Among these, rod-shaped nematic liquid crystal compounds (hereinafter simply referred to as “nematic liquid crystal compounds”) are preferable.
[0067]
The nematic liquid crystal compound can be appropriately selected from liquid crystal compounds, polymer liquid crystal compounds, and polymerizable liquid crystal compounds having a refractive index anisotropy Δn of 0.10 to 0.40. A cholesteric liquid crystal composition can be obtained by using a photoreactive chiral compound in combination with a nematic liquid crystal compound. In addition, the nematic liquid crystal compound can be aligned, for example, by using an alignment substrate that has been subjected to an alignment process such as a rubbing process while being in a liquid crystal state at the time of melting. Further, when the liquid crystal state is fixed in a solid phase, means such as cooling and polymerization can be used. That is, since the liquid crystalline compound has a polymerizable group and has extremely high reactivity, a tough film can be formed by efficiently polymerizing in an aligned state.
[0068]
Among the nematic liquid crystal compounds, for example, a liquid crystal compound in which a UV curable functional group (for example, an acrylate group) that is polymerized and cured in response to ultraviolet light is introduced into the same molecule is preferable. If this is hardened by irradiating it with ultraviolet rays, a color filter having a high film strength can be produced at a low temperature of 120 ° C. or lower.
[0069]
Specific examples of the nematic liquid crystal compound include the following compounds. However, the present invention is not limited to these.
[0070]
[Chemical 2]

[0071]
[Chemical 3]

[0072]
[Formula 4]

[0073]
In said formula, n represents the integer of 1-1000.
In each of the above exemplary compounds, those in which the side chain linking group of the aromatic ring is changed to the following structure can also be mentioned as suitable.
[0074]
[Chemical formula 5]

[0075]
Among the above, as the nematic liquid crystal compound, a compound having a polymerizable group or a crosslinkable group in the molecule is preferable from the viewpoint of excellent curability and ensuring heat resistance of the layer.
[0076]
The said liquid crystalline compound may be used individually by 1 type, and may use 2 or more types together. In addition to the “liquid crystalline compound having at least one polymerizable group”, a liquid crystalline compound having no polymerizable group may be used in combination.
The content of the “liquid crystal compound having at least one polymerizable group” is preferably 30 to 98% by mass with respect to the total solid content (mass) of the liquid crystal composition (cholesteric liquid crystal composition). -95 mass% is more preferable. When the content is less than 30% by mass, the orientation may be insufficient and a desired selective reflection color may not be obtained.
[0077]
-Polymerization initiator-
The polymerization initiator promotes a polymerization reaction based on an unsaturated bond, polymerizes and cures the liquid crystalline composition, and further improves the strength of the liquid crystalline composition after immobilization. As a polymerization initiator, it can select suitably from well-known compounds, such as photoreactivity and heat reactivity, Among these, the photoinitiator which can accelerate | stimulate reaction by light irradiation is suitable. For example, a polymerization curing reaction of a cholesteric liquid crystal composition or the like can be performed quickly, and a large intrinsic birefringence (Δn), a high-resolution, selective reflection color with high color purity can be stably obtained.
[0078]
The photopolymerization initiator can be appropriately selected from known ones such as p-methoxyphenyl-2,4-bis (trichloromethyl) -s-triazine, 2- (p-butoxystyryl)- 5-trichloromethyl 1,3,4-oxadiazole, 9-phenylacridine, 9,10-dimethylbenzphenazine, benzophenone / Michler's ketone, hexaarylbiimidazole / mercaptobenzimidazole, benzyldimethyl ketal, thioxanthone / amine, etc. It is done.
[0079]
As addition amount of the said polymerization initiator, 0.1-20 mass% of solid content (mass) of a liquid crystalline composition is preferable, and 0.5-5 mass% is more preferable. When the addition amount is less than 0.1% by mass, it may take a long time because the curing efficiency is low, and when it exceeds 20% by mass, for example, in the case of a photopolymerization initiator, from the ultraviolet region to the visible light region. The light transmittance may be inferior.
[0080]
-Air interface alignment agent-
An air interfacial alignment agent is a surfactant having an excluded volume effect. Here, having an excluded volume effect means controlling the orientation of liquid crystal (molecules) on the air interface side, that is, liquid crystal at the air interface on the surface of the layer when a layer containing a liquid crystalline composition is formed by coating, for example. This means that the spatial orientation state is controlled three-dimensionally. Specifically, it means controlling the pretilt angle of the liquid crystal molecules on the air interface side.
[0081]
The molecular structural requirement of the preferred air interface alignment agent is that it has a flexible hydrophobic portion and a molecularly rigid unit having at least one cyclic unit (hereinafter referred to as a rigid portion). . Depending on the type of liquid crystal compound used, the flexible hydrophobic portion can be a perfluoro chain or a long alkyl chain. Since the hydrophobic part is flexible, the hydrophobic part can be effectively arranged on the air side.
In addition, the air interface alignment agent may be a short molecule having a number of molecules of several hundreds, or a polymer or oligomer in which they are linked. Moreover, it is also possible to provide a polymerizable functional group depending on the purpose.
[0082]
When such an air interface alignment agent is contained, the flexible hydrophobic portion of the air interface alignment agent exists in the air interface direction, the rigid portion exists in the liquid crystal molecule direction, and the rigid portion is planar. Since it is arranged in parallel with the air interface, liquid crystal molecules can be arranged in parallel with the air interface.
On the other hand, if the rigid portions are aligned perpendicular to the air interface, liquid crystal molecules can be aligned perpendicular to the air interface.
Specifically, nonionic surfactants are preferable, and for example, the following compounds are preferable.
[0083]
[Chemical 6]

[0084]
[Chemical 7]

[0085]
The amount of the air interface aligning agent added is preferably such that the surface of the layer containing the liquid crystalline composition on the air interface side is covered by about one molecule, and is about 0. 0 to the total solid content (mass) of the liquid crystalline composition. 05-5 mass% is preferable and 0.1-1.0 mass% is more preferable. If the addition amount is less than 0.05% by mass, the effect may not be exhibited. If the addition amount exceeds 5% by mass, the air interface alignment agent itself may associate to cause phase separation from the liquid crystal. .
In addition, although the surface tension is reduced by containing an air interface alignment agent, a surfactant other than the air interface alignment agent is used in combination for the purpose of further reducing the surface tension and improving the coating property. You can also.
[0086]
The surfactant can control the orientation state of the liquid crystal molecules at the air interface on the surface of the layer in a three-dimensional manner, for example, when a coating liquid crystal composition is applied to form a layer, particularly in the case of a cholesteric liquid crystal. Can obtain a selective reflection wavelength with higher color purity.
[0087]
-Polymerizable monomer-
In the liquid crystalline composition, a polymerizable monomer may be used in combination. When the polymerizable monomer is used in combination, after patterning (in the case of cholesteric liquid crystal, the twisting force of the liquid crystal is changed by light irradiation to form a selective reflection wavelength distribution), the helical structure (selective reflectivity) is fixed, The strength of the liquid crystal layer (liquid crystal composition) after immobilization can be further improved. However, when the nematic liquid crystal compound has an unsaturated bond in the same molecule, it is not always necessary to add it.
[0088]
Examples of the polymerizable monomer include monomers having an ethylenically unsaturated bond, and specific examples include polyfunctional monomers such as pentaerythritol tetraacrylate and dipentaerythritol hexaacrylate.
Specific examples of the monomer having an ethylenically unsaturated bond include the compounds shown below, but the invention is not limited to these.
[0089]
[Chemical 8]

[0090]
As addition amount of the said polymerizable monomer, 0.5-50 mass% of the total solid (mass) of a liquid crystalline composition is preferable. If the addition amount is less than 0.5% by mass, sufficient curability may not be obtained, and if it exceeds 50% by mass, the alignment of liquid crystal molecules is inhibited and sufficient color development cannot be obtained. Sometimes.
[0091]
-Other ingredients-
Furthermore, binder resins, polymerization inhibitors, solvents, thickeners, dyes, pigments, ultraviolet absorbers, gelling agents, and the like can be added as other components.
As this other component, since it affects the intensity | strength of the color filter film | membrane hardened | cured by ultraviolet curing, a thing excellent in compatibility with a liquid crystalline compound is preferable.
[0092]
In addition, if these components are movable in the cured color filter film, the liberated components reduce the film strength and cause changes in the characteristics of the color filter. Therefore, as the other component to be added, it is preferable to use a component having the same functional group as the polymerizable functional group introduced into the liquid crystal compound. That is, other components are not released in the film and are fixed in the liquid crystal compound by polymerization and curing, so that the film strength and various properties are not hindered. Further, the content of the other components excluding the binder resin and the surfactant is preferably 10% by mass or less of the total solid content (mass) of the liquid crystal composition. When this content exceeds 10 mass%, the intensity | strength of an optical film (selective reflection film) may be reduced.
[0093]
Examples of the binder resin include polystyrene compounds such as polystyrene and poly-α-methylstyrene, cellulose resins such as methyl cellulose, ethyl cellulose, and acetyl cellulose, acidic cellulose derivatives having a carboxyl group in the side chain, polyvinyl formal, polyvinyl butyral, and the like. Acetal resins of JP-A-59-44615, JP-B-54-34327, JP-B-58-12577, JP-B-54-25957, JP-A-59-53836, JP-A-59-71048 Methacrylic acid copolymers, acrylic acid copolymers, itaconic acid copolymers, crotonic acid copolymers, maleic acid copolymers, partially esterified maleic acid copolymers, and the like.
Also included are homopolymers of acrylic acid alkyl esters and homopolymers of methacrylic acid alkyl esters, in which the alkyl group is particularly a methyl group, ethyl group, n-propyl group, n-butyl group, or iso-butyl group. , N-hexyl group, cyclohexyl group, 2-ethylhexyl group and the like are preferable.
In addition, a polymer having a hydroxyl group with an acid anhydride added, benzyl (meth) acrylate / (homopolymer of methacrylic acid) acrylic acid copolymer, benzyl (meth) acrylate / (meth) acrylic acid / other monomers And a multi-component copolymer.
[0094]
Among these, from the viewpoints of alkali developability after patterning and mass productivity, a binder resin containing a carboxyl group is preferable. When a liquid crystal layer is formed on a plastic substrate (coating, transferring, etc.), alkali development is possible by using a binder resin containing a carboxyl group as a binder component in the cholesteric liquid crystal composition prepared in a coating liquid state, and light irradiation is possible. Patterning can be easily performed by subsequent alkali development.
[0095]
As content of binder resin in a liquid crystalline composition, 0-50 mass% is preferable, and 0-30 mass% is more preferable. When the content exceeds 50% by mass, the alignment of the liquid crystal compound may be insufficient.
[0096]
The polymerization inhibitor may be added for the purpose of improving storage stability. Examples thereof include hydroquinone, hydroquinone monomethyl ether, phenothiazine, benzoquinone, and derivatives thereof. As addition amount of this polymerization inhibitor, 0-10 mass% is preferable with respect to the said polymerizable monomer, and 0-5 mass% is more preferable.
[0097]
The liquid crystalline composition can be prepared by dissolving and dispersing the above components in a solvent (in the form of a coating liquid), forming this into an arbitrary shape, or forming it on a support or the like (preferably, for example, by applying a liquid crystal Forming an adhesive composition layer). When a liquid crystalline composition layer is formed by coating, a layer having a uniform layer thickness and surface property can be obtained, and a selective reflection film having excellent optical characteristics can be formed.
Examples of the solvent include 2-butanone, cyclohexanone, methylene chloride, chloroform, and the like.
[0098]
<Selective reflective film>
The selective reflection film of the present invention can be suitably produced by the above-described method for producing a selective reflection film of the present invention. More preferably, the liquid crystalline composition having an isomerizable absorption in a wavelength region of 490 to 570 nm or 630 to 690 nm is in the same direction as the twist direction of the spiral of the liquid crystal and has a wavelength of 490 to 570 nm or 630 to 690 nm. It can be produced by patterning by irradiating circularly or elliptically polarized light like an image.
[0099]
Therefore, the selective reflection film of the present invention effectively suppresses the occurrence of color unevenness during patterning due to the unevenness even when the coating thickness is uneven. (Especially green or red hue and uniformity thereof).
[0100]
There is no restriction | limiting in particular as a form of the final selective reflection film, The sheet form comprised only from the said liquid crystalline composition, the layer (liquid crystal layer) containing a liquid crystalline composition on a desired support body or a temporary support body Or any other layer (film) such as an alignment film or a protective film may be further provided.
[0101]
In the case where a layer (liquid crystal layer) containing a liquid crystal composition is provided on a desired support or temporary support, the liquid crystal layer is polymerized with a liquid crystal compound (nematic liquid crystal compound), a photoreactive chiral compound, and polymerization. And a cholesteric liquid crystal composition each containing at least one agent, and may contain other components such as a polymerizable monomer, a surfactant, and a binder resin as necessary.
In the present invention, it is particularly preferable to use an air interface alignment agent and a polymerizable monomer in combination. By including the air interface alignment agent, a selective reflection wavelength having particularly high color purity can be obtained as described above.
[0102]
As described above, since the cholesteric liquid crystal composition is used, it is a non-light-absorbing selective reflection film, and exhibits various hues in which the wavelength range of selective reflection of the liquid crystal is widened. A selective reflection film that is particularly excellent in uniformity and resolution, for example, a high-resolution color filter composed of primary colors (B, G, R) with high color purity, high patterning accuracy, and good color fractionation. be able to.
[0103]
The selective reflection film of the present invention is a (layered) color filter, a retardation film, a circularly polarizing reflector, a brightness enhancement film for a transmissive LCD, a projector for a color wheel, etc. It can be suitably used for optical parts used in coatings, decorative items such as painting, high-gloss (metallic) printed matter, anti-counterfeiting displays, and the like.
[0104]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.
(Example 1)
(1) Preparation of filter substrate
A polyimide alignment film (LX-1400, manufactured by Hitachi Chemical DuPont Co., Ltd.) coating solution is applied onto a glass substrate with a spin coater, dried in an oven at 100 ° C. for 5 minutes, and then baked in an oven at 250 ° C. for 1 hour. An alignment film was formed. Further, the surface of the film was subjected to orientation treatment by rubbing treatment to produce a glass substrate with an orientation film.
[0105]
(2) Formation of filter layer
On the alignment film of the glass substrate with an alignment film obtained as described above, the photosensitive liquid crystal layer coating solution (1) prepared by the following formulation was applied by a spin coater and dried in an oven at 100 ° C. for 2 minutes. Thus, a photosensitive liquid crystal layer (liquid crystal composition layer) was formed (layer forming step). The layer thickness was measured by a confocal microscope and found to be 2.3 μm.
[0106]
[Chemical 9]

[0107]
Next, the glass substrate on which the photosensitive liquid crystal layer was formed was held on a hot plate at 100 ° C. for 3 minutes so as to be in contact with the surface of the glass substrate, and the photosensitive liquid crystal layer was aligned (colored). At this time, the photosensitive liquid crystal layer became a liquid crystal phase and exhibited selective reflection with a central wavelength of 450 nm (blue formation).
Subsequently, in a state maintained at 80 ° C., the photosensitive liquid crystal layer has a stripe-shaped photomask having an opening with a line width of 80 μm and an opening pitch of 270 μm, an interference filter having a transmission center wavelength at 530 nm, Xenon light (λ) through the plate and λ / 4 plate (left circularly polarized light) ¹ ) For 10 seconds (irradiation intensity 5 mW / cm) ² And patterned. At this time (80 ° C.), the light irradiation portion of the photosensitive liquid crystal layer showed green selective reflection. Subsequently, while maintaining the temperature at 80 ° C., the photomask is moved by 90 μm in the line width direction, and irradiated for 5 seconds through the photomask and the interference filter (λ ¹ Irradiation intensity 40 mW / cm ² And patterned. Then, the light irradiation part of the photosensitive liquid crystal layer showed red selective reflection (80 ° C.). The unirradiated portion of the photosensitive liquid crystal layer exhibited blue selective reflection (alignment process). As described above, a pattern showing selective reflection in blue (B), green (G), and red (R) was formed on the photosensitive liquid crystal layer.
[0108]
Next, this glass substrate is held on a hot plate at 60 ° C. and irradiated with an ultrahigh pressure mercury lamp for 5 seconds under an atmosphere of nitrogen through an interference filter having a transmission center wavelength at 313 nm (λ ² Irradiation intensity 100 mW / cm ² The photosensitive liquid crystal layer was polymerized and cured. Furthermore, for the purpose of accelerating the curing of the film, heat treatment was performed at 250 ° C. for 15 minutes to obtain a color filter according to the present invention.
[0109]
The center wavelengths indicating selective reflection of B, G, and R of the obtained color filter were 440 nm, 530 nm, and 650 nm, respectively, and hues with high color purity were obtained for each color. In addition, for each color, the variation in the center wavelength of selective reflection between each pixel in the color filter is within ± 2 nm, which is excellent in terms of hue uniformity.
[0110]
(Example 2)
In the same manner as in Example 1, a glass substrate with an alignment film as a filter substrate was prepared, and instead of the photosensitive liquid crystal layer coating liquid (1) used in Example 1, a photosensitive liquid crystal layer having the following formulation was used. A photosensitive liquid crystal layer was formed on the alignment film in the same manner as in Example 1 except that the coating liquid (2) was used (layer forming step). The layer thickness was measured by a confocal microscope and found to be 2.3 μm.
[0111]
Embedded image

[0112]
Next, the glass substrate on which the photosensitive liquid crystal layer was formed in the same manner as in Example 1 was held on a hot plate at 100 ° C. for 3 minutes to align (color) the photosensitive liquid crystal layer. At this time, the photosensitive liquid crystal layer became a liquid crystal phase and exhibited selective reflection with a central wavelength of 455 nm (blue formation).
Subsequently, while maintaining at 80 ° C., the photosensitive liquid crystal layer was applied to the photosensitive liquid crystal layer as in Example 1 (photomask, interference filter having a transmission center wavelength at 530 nm, a polarizing plate, and a λ / 4 plate (left circle). Xenon light (λ) ¹ ) For 20 seconds (irradiation intensity 5 mW / cm) ² )did. At this time (80 ° C.), the light irradiation portion of the photosensitive liquid crystal layer showed green selective reflection. Subsequently, the sample was irradiated for 10 seconds in the same manner as in Example 1 (via a photomask and an interference filter) while being held at 80 ° C. ¹ Irradiation intensity 40 mW / cm ² )did. At this time (80 ° C.), the light irradiation part of the photosensitive liquid crystal layer showed red selective reflection. The unirradiated portion of the photosensitive liquid crystal layer exhibited blue selective reflection (alignment process). As described above, a pattern showing selective reflection in blue (B), green (G), and red (R) was formed on the photosensitive liquid crystal layer.
[0113]
Next, in the same manner as in Example 1, irradiation with an ultrahigh pressure mercury lamp for 5 seconds (λ ² The photosensitive liquid crystal layer was polymerized and cured, and further heat-treated at 250 ° C. for 15 minutes to obtain a color filter according to the present invention.
The center wavelengths indicating selective reflection of B, G, and R of the obtained color filter were 445 nm, 532 nm, and 655 nm, respectively, and hues with high color purity were obtained for each color. In addition, for each color, the variation in the center wavelength of selective reflection between each pixel in the color filter is within ± 2 nm, which is excellent in terms of hue uniformity.
[0114]
【The invention's effect】
According to the present invention, simple and satisfactory alignment treatment is possible, and a hue with uniform and high color purity (especially green or red) is avoided by avoiding a decrease in color purity and resolution due to hue shift caused by uneven irradiation or the like. And a method for producing a selective reflection film capable of performing color fractionation (patterning) with high accuracy can be provided. In addition, a selective reflection film having excellent hue and color uniformity, particularly green or red hue and its uniformity, image characteristics excellent in color resolution (patterning accuracy), and excellent optical characteristics. Can be provided.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the amount of light applied to a photoreactive liquid crystalline composition and the selective reflection wavelength.
FIG. 2 is a schematic process diagram for explaining a process until a cholesteric liquid crystal layer is formed on a substrate.
FIG. 3 is a schematic process diagram for explaining a process until a cholesteric liquid crystal layer is formed on a substrate.
FIG. 4 is a schematic view showing that a multicolor pattern consisting of three colors of RGB is formed according to the first embodiment in the method for producing a selective reflection film of the present invention.
FIG. 5 is a schematic process diagram for explaining that RGB three colors are formed like an image by repeating the process of forming a monochromatic pattern according to the second embodiment in the method of manufacturing a selective reflection film of the present invention. .
[Explanation of symbols]
4, 4 '... Photomask
10 Temporary support
12 ... Cushion layer (thermoplastic resin layer)
24. Alignment film
16. Cholesteric liquid crystal layer (phase)
20 ... transfer sheet
22 ... Base material (support)
26 ... Color filter substrate
28 ... Mask

Claims (8)

A liquid crystalline composition containing a liquid crystalline compound having at least one polymerizable group, a photoreactive chiral compound having absorption isomerizable in the visible light region, and a polymerization initiator is image-likely light (wavelength λ ¹ ) A method for producing a selective reflection film that irradiates and forms a pattern showing selective reflection according to the irradiation,
One of the circularly polarized light and the elliptically polarized light having the same direction as the twist direction of the spiral of the liquid crystal is used for the light irradiation. The liquid crystalline composition is irradiated with light having a wavelength λ ¹ to form an exposure amount distribution on the liquid crystalline composition, and after having been in a state of selective reflection according to the exposure amount distribution, the liquid crystalline composition in this state Irradiating the object with light of wavelength λ ² to form a multicolor pattern by polymerizing and curing in an image-like manner,
The method for manufacturing a selective reflection film according to claim 1, wherein the light having the wavelength λ ¹ is ^one of circularly polarized light and elliptically polarized light in the same direction as the twist direction of the spiral of the liquid crystal. The liquid crystal composition is irradiated with light having a wavelength λ ^{1 in} an image-like manner to show selective reflection in accordance with the irradiation, and then the region of the state is further irradiated with light having a wavelength λ ² to be polymerized in an image-like manner. Including at least one step of curing to form a monochromatic pattern,
The method for manufacturing a selective reflection film according to claim 1, wherein the light having the wavelength λ ¹ is ^one of circularly polarized light and elliptically polarized light in the same direction as the twist direction of the spiral of the liquid crystal. A liquid crystal composition in a state of selective reflection of the first color is irradiated with light having a wavelength λ ² to form a monochromatic pattern by polymerizing and curing in an image-like manner, and further selecting a wavelength different from that of the first color By changing the irradiation amount of the light of wavelength λ ¹ to (n−1) steps so as to show reflection and repeating the process of forming a monochromatic pattern (n−1) times, a multicolor pattern composed of n colors is obtained. The manufacturing method of the selective reflection film according to claim 3 to form. The photoreactive chiral compound has isomerizable absorption in a wavelength region of 490 to 570 nm or 630 to 690 nm, and the light of wavelength λ ¹ is light of a wavelength of 490 to 570 nm or 630 to 690 nm. 5. The method for producing a selective reflection film according to any one of 4 above. The wavelength λ ¹ (nm) satisfies (λ−50) ≦ λ ¹ ≦ (λ + 50) with respect to the isomerizable absorption wavelength λ (nm) of the photoreactive chiral compound. The manufacturing method of the selective reflection film | membrane of description. The method for producing a selective reflection film according to claim 1, wherein the liquid crystalline composition contains an air interface alignment agent. A selective reflection film obtained by the method for producing a selective reflection film according to claim 1.

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