JP4199488B2 - Retardation plate and circularly polarizing plate - Google Patents

Description

【００３０】
重合性基（Ｑ１およびＱ２）は、不飽和重合性基（Ｑ−１〜Ｑ−７）、エポキシ基（Ｑ−８）またはアジリジニル基（Ｑ−９）であることが好ましく、不飽和重合性基であることがさらに好ましく、エチレン性不飽和重合性基（Ｑ−１〜Ｑ−６）であることが最も好ましい。
【００３１】
式（Ｉ）において、Ｌ１およびＬ４は、それぞれ独立に、二価の連結基である。
Ｌ１およびＬ４は、それぞれ独立に、−Ｏ−、−Ｓ−、−ＣＯ−、−ＮＲ１−、二価の鎖状脂肪族基、二価の環状基およびそれらの組み合わせからなる群より選ばれる二価の連結基であることが好ましい。上記Ｒ１は、炭素原子数が１乃至７のアルキル基または水素原子である。
組み合わせからなる二価の連結基の例を以下に示す。左側がＱ（Ｑ１またはＱ２）に、右側がＣｙ（Ｃｙ１またはＣｙ２）に結合する。
【００３２】
Ｌ−１：−ＣＯ−Ｏ−二価の鎖状脂肪族基−Ｏ−
Ｌ−２：−ＣＯ−Ｏ−二価の鎖状脂肪族基−Ｏ−二価の環状基−ＣＯ−Ｏ−
Ｌ−３：−ＣＯ−Ｏ−二価の鎖状脂肪族基−Ｏ−二価の環状基−Ｏ−ＣＯ−
Ｌ−４：−ＣＯ−Ｏ−二価の鎖状脂肪族基−Ｏ−二価の環状基−二価の鎖状脂肪族基−
Ｌ−５：−ＣＯ−Ｏ−二価の鎖状脂肪族基−Ｏ−二価の環状基−
Ｌ−６：−ＣＯ−Ｏ−二価の鎖状脂肪族基−Ｏ−二価の環状基−二価の鎖状脂肪族基−ＣＯ−Ｏ−
Ｌ−７：−ＣＯ−Ｏ−二価の鎖状脂肪族基−Ｏ−二価の環状基−Ｏ−ＣＯ−二価の鎖状脂肪族基−
【００３３】
二価の鎖状脂肪族基は、アルキレン基、置換アルキレン基、アルケニレン基、置換アルケニレン基、アルキニレン基または置換アルキニレン基を意味する。アルキレン基、置換アルキレン基、アルケニレン基および置換アルケニレン基が好ましく、アルキレン基およびアルケニレン基がさらに好ましい。
アルキレン基は、分岐を有していてもよい。アルキレン基の炭素原子数は、１乃至１２であることが好ましく、２乃至１０であることがさらに好ましく、３乃至８であることが最も好ましい。
置換アルキレン基のアルキレン部分は、上記アルキレン基と同様である。置換アルキレン基の置換基の例には、ハロゲン原子が含まれる。
アルケニレン基は、分岐を有していてもよい。アルケニレン基の炭素原子数は、２乃至１２であることが好ましく、２乃至８であることがさらに好ましく、２乃至４であることが最も好ましい。
置換アルケニレン基のアルケニレン部分は、上記アルケニレン基と同様である。置換アルケニレン基の置換基の例には、ハロゲン原子が含まれる。
アルキニレン基は、分岐を有していてもよい。アルキニレン基の炭素原子数は、２乃至１２であることが好ましく、２乃至８であることがさらに好ましく、２乃至４であることが最も好ましい。
置換アルキニレン基のアルキニレン部分は、上記アルキニレン基と同様である。置換アルキニレン基の置換基の例には、ハロゲン原子が含まれる。
【００３４】
二価の環状基の定義および例は、後述するＣｙ１〜Ｃｙ３の定義および例と同様である。
Ｒ１は、炭素原子数が１乃至４のアルキル基または水素原子であることが好ましく、炭素原子数が１または２のアルキル基または水素原子であることがさらに好ましく、水素原子であることが最も好ましい。
【００３５】
式（Ｉ）において、Ｌ２またはＬ３は、それぞれ独立に、単結合または二価の連結基である。
二価の連結基は、−Ｏ−、−Ｓ−、−ＣＯ−、−ＮＲ２−、二価の鎖状脂肪族基、二価の環状基およびそれらの組み合わせからなる群より選ばれる二価の連結基であることが好ましい。上記Ｒ２は、炭素原子数が１乃至７のアルキル基または水素原子である。
二価の鎖状脂肪族基の定義および例は、Ｌ１およびＬ４の定義および例と同様である。
二価の環状基の定義および例は、後述するＣｙ１〜Ｃｙ３の定義および例と同様である。
Ｒ２は、炭素原子数が１乃至４のアルキル基または水素原子であることが好ましく、炭素原子数が１または２のアルキル基または水素原子であることがさらに好ましく、水素原子であることが最も好ましい。
【００３６】
式（Ｉ）において、Ｃｙ１、Ｃｙ２およびＣｙ３は、それぞれ独立に、二価の環状基である。
環状基に含まれる環は、５員環、６員環または７員環であることが好ましく、５員環または６員環であることがさらに好ましく、６員環であることが最も好ましい。
環状基に含まれる環は、縮合環であってもよい。ただし、縮合環よりも単環である方が好ましい。
環状基に含まれる環は、芳香族環、脂肪族環および複素環のいずれでもよい。芳香族環の例には、ベンゼン環およびナフタレン環が含まれる。脂肪族環の例には、シクロヘキサン環が含まれる。複素環の例には、ピリジン環およびピリミジン環が含まれる。
【００３７】
ベンゼン環を有する環状基としては、１，４−フェニレンが好ましい。ナフタレン環を有する環状基としては、ナフタレン−１，５−ジイルおよびナフタレン−２，６−ジイルが好ましい。ピリジン環を有する環状基としては、ピリジン−２，５−ジイルが好ましい。ピリミジン環を有する環状基としては、ピリミジン−２，５−ジイルが好ましい。
環状基は、１，４−フェニレンまたは１，４−シクロへキシレンであることが特に好ましい。
環状基は、置換基を有していてもよい。置換基の例には、ハロゲン原子、シアノ、ニトロ、炭素原子数が１乃至５のアルキル基、炭素原子数が１乃至５のハロゲン置換アルキル基、炭素原子数が１乃至５のアルコキシ基、炭素原子数が１乃至５のアルキルチオ基、炭素原子数が１乃至５のアシル基、炭素原子数が２乃至６のアシルオキシ基、炭素原子数が２乃至６のアルコキシカルボニル基、カルバモイル、炭素原子数が２乃至６のアルキル置換カルバモイル基および炭素原子数が２乃至６のアミド基が含まれる。
【００３８】
式（Ｉ）において、ｎは、０、１または２である。ｎが２の場合、二つのＬ３およびＣｙ２は、異なっていてもよい。ｎは、１または２であることが好ましく、１であることがさらに好ましい。
以下に、式（Ｉ）で表される重合性液晶化合物の例を示す。
【００３９】
【化２】

【００４０】
【化３】

【００４１】
【化４】

【００４２】
【化５】

【００４３】
【化６】

【００４４】
【化７】

【００４５】
【化８】

【００４６】
【化９】

【００４７】
【化１０】

【００４８】
【化１１】

【００４９】
【化１２】

【００５０】
【化１３】

【００５１】
【化１４】

【００５２】
【化１５】

【００５３】
【化１６】

【００５４】
ディスコティック液晶性分子は、様々な文献（C. Destrade et al., Mol. Crysr. Liq. Cryst., vol. 71, page 111 (1981) ；日本化学会編、季刊化学総説、Ｎｏ．２２、液晶の化学、第５章、第１０章第２節(1994)；B. Kohne et al., Angew. Chem. Soc. Chem. Comm., page 1794 (1985)；J. Zhang et al., J. Am.Chem. Soc., vol. 116, page 2655 (1994)）に記載されている。ディスコティック液晶性分子の重合については、特開平８−２７２８４公報に記載がある。
ディスコティック液晶性分子を重合により固定するためには、ディスコティック液晶性分子の円盤状コアに、置換基として重合性基を結合させる必要がある。ただし、円盤状コアに重合性基を直結させると、重合反応において配向状態を保つことが困難になる。そこで、円盤状コアと重合性基との間に、連結基を導入する。従って、重合性基を有するディスコティック液晶性分子は、下記式（II）で表わされる化合物であることが好ましい。
【００５５】
（II）Ｄ（−Ｌ−Ｑ）ｎ
式（II）において、Ｄは、円盤状コアであり、Ｌは、二価の連結基であり、Ｑは重合性基であり、そして、ｎは４乃至１２の整数である。
式（II）の円盤状コア（Ｄ）の例を以下に示す。以下の各例において、ＬＱ（またはＱＬ）は、二価の連結基（Ｌ）と重合性基（Ｑ）との組み合わせを意味する。
【００５６】
【化１７】

【００５７】
【化１８】

【００５８】
【化１９】

【００５９】
【化２０】

【００６０】
【化２１】

【００６１】
【化２２】

【００６２】
【化２３】

【００６３】
式（II）において、二価の連結基（Ｌ）は、アルキレン基、アルケニレン基、アリーレン基、−ＣＯ−、−ＮＨ−、−Ｏ−、−Ｓ−およびそれらの組み合わせからなる群より選ばれる二価の連結基であることが好ましい。二価の連結基（Ｌ）は、アルキレン基、アルケニレン基、アリーレン基、−ＣＯ−、−ＮＨ−、−Ｏ−および−Ｓ−からなる群より選ばれる二価の基を少なくとも二つ組み合わせた基であることがさらに好ましく、アルキレン基、アルケニレン基、アリーレン基、−ＣＯ−および−Ｏ−からなる群より選ばれる二価の基を少なくとも二つ組み合わせた基であることが最も好ましい。アルキレン基の炭素原子数は、１乃至１２であることが好ましい。アルケニレン基の炭素原子数は、２乃至１２であることが好ましい。アリーレン基の炭素原子数は、６乃至１０であることが好ましい。アルキレン基、アルケニレン基およびアリーレン基は、置換基（例、アルキル基、ハロゲン原子、シアノ、アルコキシ基、アシルオキシ基）を有していてもよい。
【００６４】
二価の連結基（Ｌ）の例を以下に示す。左側が円盤状コア（Ｄ）に結合し、右側が重合性基（Ｑ）に結合する。ＡＬはアルキレン基またはアルケニレン基を意味し、ＡＲはアリーレン基を意味する。
Ｌ−１１：−ＡＬ−ＣＯ−Ｏ−ＡＬ−
Ｌ−１２：−ＡＬ−ＣＯ−Ｏ−ＡＬ−Ｏ−
Ｌ−１３：−ＡＬ−ＣＯ−Ｏ−ＡＬ−Ｏ−ＡＬ−
Ｌ−１４：−ＡＬ−ＣＯ−Ｏ−ＡＬ−Ｏ−ＣＯ−
Ｌ−１５：−ＣＯ−ＡＲ−Ｏ−ＡＬ−
Ｌ−１６：−ＣＯ−ＡＲ−Ｏ−ＡＬ−Ｏ−
Ｌ−１７：−ＣＯ−ＡＲ−Ｏ−ＡＬ−Ｏ−ＣＯ−
Ｌ−１８：−ＣＯ−ＮＨ−ＡＬ−
Ｌ−１９：−ＮＨ−ＡＬ−Ｏ−
Ｌ−２０：−ＮＨ−ＡＬ−Ｏ−ＣＯ−
【００６５】
Ｌ−２１：−Ｏ−ＡＬ−
Ｌ−２２：−Ｏ−ＡＬ−Ｏ−
Ｌ−２３：−Ｏ−ＡＬ−Ｏ−ＣＯ−
Ｌ−２４：−Ｏ−ＡＬ−Ｏ−ＣＯ−ＮＨ−ＡＬ−
Ｌ−２５：−Ｏ−ＡＬ−Ｓ−ＡＬ−
Ｌ−２６：−Ｏ−ＣＯ−ＡＬ−ＡＲ−Ｏ−ＡＬ−Ｏ−ＣＯ−
Ｌ−２７：−Ｏ−ＣＯ−ＡＲ−Ｏ−ＡＬ−ＣＯ−
Ｌ−２８：−Ｏ−ＣＯ−ＡＲ−Ｏ−ＡＬ−Ｏ−ＣＯ−
Ｌ−２９：−Ｏ−ＣＯ−ＡＲ−Ｏ−ＡＬ−Ｏ−ＡＬ−Ｏ−ＣＯ−
Ｌ−３０：−Ｏ−ＣＯ−ＡＲ−Ｏ−ＡＬ−Ｏ−ＡＬ−Ｏ−ＡＬ−Ｏ−ＣＯ−
Ｌ−３１：−Ｓ−ＡＬ−
Ｌ−３２：−Ｓ−ＡＬ−Ｏ−
Ｌ−３３：−Ｓ−ＡＬ−Ｏ−ＣＯ−
Ｌ−３４：−Ｓ−ＡＬ−Ｓ−ＡＬ−
Ｌ−３５：−Ｓ−ＡＲ−ＡＬ−
【００６６】
式（II）の重合性基（Ｑ）は、重合反応の種類に応じて決定する。重合性基（Ｑ）の定義および例は、式（Ｉ）におけるＱ１およびＱ２の定義および例と同様である。
【００６７】
複数のＬとＱの組み合わせは、異なっていてもよいが、同一であることが好ましい。二種類以上のディスコティック液晶性分子（例えば、二価の連結基に不斉炭素原子を有する分子と有していない分子）を併用してもよい。
【００６８】
光学異方性層は、液晶性分子および下記の重合開始剤や他の添加剤を含む塗布液を、配向膜の上に塗布することで形成する。光学異方性層中の液晶性分子の割合は、１０乃至５０質量％であることが好ましい。
塗布液の調製に使用する溶媒としては、有機溶媒が好ましく用いられる。有機溶媒の例には、アミド（例、Ｎ，Ｎ−ジメチルホルムアミド）、スルホキシド（例、ジメチルスルホキシド）、ヘテロ環化合物（例、ピリジン）、炭化水素（例、ベンゼン、ヘキサン）、アルキルハライド（例、クロロホルム、ジクロロメタン）、エステル（例、酢酸メチル、酢酸ブチル）、ケトン（例、アセトン、メチルエチルケトン）、エーテル（例、テトラヒドロフラン、１，２−ジメトキシエタン）が含まれる。アルキルハライドおよびケトンが好ましい。二種類以上の有機溶媒を併用してもよい。塗布液の塗布は、公知の方法（例、押し出しコーティング法、ダイレクトグラビアコーティング法、リバースグラビアコーティング法、ダイコーティング法）により実施できる。
【００６９】
配向させた液晶性分子は、配向状態を維持して固定する。固定化は、液晶性分子に導入した重合性基（Ｑ）の重合反応により実施することが好ましい。重合反応には、熱重合開始剤を用いる熱重合反応と光重合開始剤を用いる光重合反応とが含まれる。光重合反応が好ましい。光重合開始剤の例には、α−カルボニル化合物（米国特許２３６７６６１号、同２３６７６７０号の各明細書記載）、アシロインエーテル（米国特許２４４８８２８号明細書記載）、α−炭化水素置換芳香族アシロイン化合物（米国特許２７２２５１２号明細書記載）、多核キノン化合物（米国特許３０４６１２７号、同２９５１７５８号の各明細書記載）、トリアリールイミダゾールダイマーとｐ−アミノフェニルケトンとの組み合わせ（米国特許３５４９３６７号明細書記載）、アクリジンおよびフェナジン化合物（特開昭６０−１０５６６７号公報、米国特許４２３９８５０号明細書記載）およびオキサジアゾール化合物（米国特許４２１２９７０号明細書記載）が含まれる。
【００７０】
光重合開始剤の使用量は、塗布液の固形分の０．０１乃至２０質量％であることが好ましく、０．５乃至５質量％であることがさらに好ましい。液晶性分子の重合のための光照射は、紫外線を用いることが好ましい。照射エネルギーは、２０ｍＪ／ｃｍ² 乃至５０Ｊ／ｃｍ² であることが好ましく、１００乃至８００ｍＪ／ｃｍ² であることがさらに好ましい。光重合反応を促進するため、加熱条件下で光照射を実施してもよい。光学異方性層の厚さは、０．１乃至１０μｍであることが好ましく、０．５乃至５μｍであることがさらに好ましい。
【００７１】
［配向膜］
液晶性分子を配向させるために配向膜を用いることが好ましい。
配向膜は、有機化合物（好ましくはポリマー）のラビング処理、無機化合物の斜方蒸着、マイクログルーブを有する層の形成、あるいはラングミュア・ブロジェット法（ＬＢ膜）による有機化合物（例、ω−トリコサン酸、ジオクタデシルメチルアンモニウムクロライド、ステアリル酸メチル）の累積のような手段で、設けることができる。さらに、電場の付与、磁場の付与あるいは光照射により、配向機能が生じる配向膜も知られている。ポリマーのラビング処理により形成する配向膜が特に好ましい。ラビング処理は、ポリマー層の表面を、紙や布で一定方向に、数回こすることにより実施する。
【００７２】
本発明では、棒状液晶性分子またはディスコティック液晶性分子をホモジニアスに配向させる。ただし、同じ「ホモジニアス」と称していても、棒状液晶性分子とディスコティック液晶性分子とは、著しく相違する。従って、配向膜に使用するポリマーは、液晶化合物の種類（棒状液晶性分子またはディスコティック液晶性分子）に応じて決定する必要がある。
棒状液晶性分子をホモジニアス（水平）に配向させるためには、配向膜の表面エネルギーを低下させないポリマー（通常の配向膜用ポリマー）を用いる。
ディスコティック液晶性分子をホモジニアス（垂直）に配向させるためには、配向膜の表面エネルギーを低下させるポリマーを用いる。配向膜の表面エネルギーを低下させるためには、ポリマーの側鎖に炭素原子数が１０乃至１００の炭化水素基を導入することが好ましい。
【００７３】
具体的なポリマーの種類については、液晶セル（主に棒状液晶性分子）または光学補償シート（主にディスコティック液晶性分子）についての様々な文献に記載がある。
配向膜の厚さは、０．０１乃至５μｍであることが好ましく、０．０５乃至１μｍであることがさらに好ましい。
なお、配向膜を用いて、光学異方性層の液晶化合物を配向させてから、液晶層を透明支持体上に転写してもよい。配向状態で固定された液晶化合物は、配向膜がなくても配向状態を維持することができる。
【００７４】
本発明では、光学異方性層の面内の遅相軸と透明支持体の長手方向との角度を実質的に７５゜または１５゜に設定する。
一般的な配向膜は、ラビング方向と、液晶性分子からなる光学異方性層の遅相軸方向とが平行になる。光学異方性層の面内の遅相軸と透明支持体の長手方向との角度を実質的に１５゜に設定する場合は、一般的な配向膜（平行型配向膜）を用いて、透明支持体の長手方向に対して１５゜の方向にラビング処理を実施することが好ましい。すなわち、透明支持体の長手方向と、ラビング方向との角度は、なるべく小さい角度（７５゜よりも１５゜）になることが好ましい。
【００７５】
一方、光学異方性層の面内の遅相軸と透明支持体の長手方向との角度を実質的に７５゜に設定する場合は、特別な配向膜（直交型配向膜）を用いて、透明支持体の長手方向に対して１５゜の方向にラビング処理を実施することが好ましい。直交型配向膜を用いると、ラビング方向と、液晶性分子からなる光学異方性層の遅相軸方向とを実質的に垂直にすることができる。その結果、透明支持体の長手方向と、ラビング方向との角度を、なるべく小さい角度（７５゜よりも１５゜）に設定できる。
【００７６】
直交型配向膜は、下記式（III)または（IV）で表される繰り返し単位と、下記式（Ｖ）で表される繰り返し単位とを含むコポリマーを含むことが好ましい。
【００７７】
【化２４】

【００７８】
式（III)において、Ｒ¹ は、水素原子（アクリル酸コポリマー）またはメチル（メタクリル酸コポリマー）である。
式（III)において、Ｍは、プロトン，アルカリ金属（例、Ｌｉ、Ｎａ、Ｋ）イオンまたはアンモニウムイオンである。アンモニウムイオンは、有機基（例、メチル、エチル）により置換されていてもよい。
式（III)において、ｍは、１０乃至９５モル％である。
【００７９】
式（Ｖ）において、Ｒ² は、水素原子、ハロゲン原子または炭素原子数が１乃至６のアルキル基である。Ｒ² は、水素原子または炭素原子数が１乃至６のアルキル基であることが好ましく、水素原子、メチルまたはエチルであることがさらに好ましく、水素原子またはメチルであることが最も好ましい。
【００８０】
式（Ｖ）において、Ｃｙは、脂肪族環基、芳香族基または複素環基である。
脂肪族環基の脂肪族環は、５員乃至７員環であることが好ましく、５員環または６員環であることがさらに好ましく、６員環であることが最も好ましい。脂肪族環の例には、シクロヘキサン環、シクロヘキセン環およびビシクロ［２．２．１］ヘプタ−２−エン環が含まれる。脂肪族環に、他の脂肪族環、芳香族環または複素環が縮合していてもよい。
芳香族基の芳香族環の例には、ベンゼン環、ナフタレン環、アントラセン環、フェナントレン環、ピレン環およびナフタセン環が含まれる。芳香族環に、脂肪族環または複素環が縮合していてもよい。
複素環基の複素環は、５員乃至７員環であることが好ましく、５員環または６員環であることがさらに好ましい。複素環は、芳香族性を有することが好ましい。芳香族性複素環は、一般に不飽和であり、好ましくは最多二重結合を有する。複素環の例には、フラン環、チオフェン環、ピロール環、オキサゾール環、イソオキサゾール環、イソチアゾール環、イミダゾール環、ピラゾール環、フラザン環、ピラン環、ピリジン環、ピリダジン環、ピリミジン環およびピラジン環が含まれる。複素環に、他の複素環、脂肪族環または芳香族環が縮合していてもよい。
【００８１】
脂肪族環基、芳香族基および複素環基は、置換基を有していてもよい。置換基の例には、アルキル基（例、メチル、エチル、ｔ−ブチル）、置換アルキル基（例、クロロメチル、ヒドロキシメチル、塩化トリメチルアンモニオ）、アルコキシ基（例、メトキシ）、ハロゲン原子（Ｆ、Ｃｌ、Ｂｒ）、カルボキシル、アシル基（例、ホルミル）、アミノ、スルホ、アリール基（例、フェニル）、アリールオキシ基（例、フェノキシ）およびオキソが含まれる。
式（Ｖ）において、ｎは、９０乃至５モル％である。
以下に式（Ｖ）で表される繰り返し単位の例を示す。
【００８２】
【化２５】

【００８３】
【化２６】

【００８４】
【化２７】

【００８５】
【化２８】

【００８６】
【化２９】

【００８７】
以下に、下記式（III)で表される繰り返し単位と、下記式（Ｖ）で表される繰り返し単位とを含むコポリマー、すなわち、アクリル酸コポリマーまたはメタクリル酸コポリマーの例を示す。ＡＡはアクリル酸から誘導される繰り返し単位であり、ＭＡはメタクリル酸から誘導される繰り返し単位である。繰り返し単位の割合は、モル％である。
【００８８】
ＰＡ１０１：−（ＡＡ）₇₀−（Ｖ−１）₃₀−
ＰＡ１０２：−（ＡＡ）₆₀−（Ｖ−１）₄₀−
ＰＡ１０３：−（ＡＡ）₅₀−（Ｖ−１）₅₀−
ＰＡ１０４：−（ＡＡ）₄₀−（Ｖ−１）₆₀−
ＰＡ１０５：−（ＡＡ）₆₀−（Ｖ−２）₄₀−
ＰＡ１０６：−（ＡＡ）₆₀−（Ｖ−３）₄₀−
ＰＡ１０７：−（ＡＡ）₆₀−（Ｖ−４）₄₀−
ＰＡ１０８：−（ＡＡ）₆₀−（Ｖ−５）₄₀−
ＰＡ１０９：−（ＡＡ）₄₀−（Ｖ−６）₄₀−
ＰＡ１１０：−（ＡＡ）₅₀−（Ｖ−７）₅₀−
ＰＡ１１１：−（ＡＡ）₇₀−（Ｖ−８）₃₀−
【００８９】
ＰＡ１１２：−（ＡＡ）₆₀−（Ｖ−９）₄₀−
ＰＡ１１３：−（ＡＡ）₆₀−（Ｖ−１０）₄₀−
ＰＡ１１４：−（ＡＡ）₆₀−（Ｖ−１１）₄₀−
ＰＡ１１５：−（ＡＡ）₅₀−（Ｖ−１２）₅₀−
ＰＡ１１６：−（ＡＡ）₅₀−（Ｖ−１３）₅₀−
ＰＡ１１７：−（ＡＡ）₇₀−（Ｖ−１４）₃₀−
ＰＡ１１８：−（ＡＡ）₅₀−（Ｖ−１５）₅₀−
ＰＡ１１９：−（ＡＡ）₆₀−（Ｖ−１６）₄₀−
ＰＡ１２０：−（ＡＡ）₆₀−（Ｖ−１７）₄₀−
ＰＡ１２１：−（ＡＡ）₆₀−（Ｖ−１８）₄₀−
ＰＡ１２２：−（ＡＡ）₆₀−（Ｖ−１９）₄₀−
【００９０】
ＰＡ１２３：−（ＡＡ）₇₅−（Ｖ−２０）₂₅−
ＰＡ１２４：−（ＡＡ）₆₀−（Ｖ−２０）₄₀−
ＰＡ１２５：−（ＡＡ）₇₀−（Ｖ−２１）₃₀−
ＰＡ１２６：−（ＡＡ）₈₀−（Ｖ−２２）₂₀−
ＰＡ１２７：−（ＡＡ）₇₀−（Ｖ−２２）₃₀−
ＰＡ１２８：−（ＡＡ）₆₀−（Ｖ−２２）₄₀−
ＰＡ１２９：−（ＡＡ）₇₀−（Ｖ−２３）₃₀−
ＰＡ１３０：−（ＡＡ）₇₀−（Ｖ−２４）₃₀−
ＰＡ１３１：−（ＡＡ）₈₀−（Ｖ−２５）₂₀−
ＰＡ１３２：−（ＡＡ）₇₀−（Ｖ−２５）₃₀−
ＰＡ１３３：−（ＡＡ）₆₀−（Ｖ−２５）₄₀−
【００９１】
ＰＡ１３４：−（ＡＡ）₆₀−（Ｖ−２６）₄₀−
ＰＡ１３５：−（ＡＡ）₇₀−（Ｖ−２７）₃₀−
ＰＡ１３６：−（ＡＡ）₈₀−（Ｖ−２８）₂₀−
ＰＡ１３７：−（ＡＡ）₇₀−（Ｖ−２９）₃₀−
ＰＡ１３８：−（ＡＡ）₆₀−（Ｖ−３０）₄₀−
ＰＡ１３９：−（ＡＡ）₇₀−（Ｖ−３１）₃₀−
ＰＡ１４０：−（ＡＡ）₇₀−（Ｖ−３２）₃₀−
ＰＡ１４１：−（ＡＡ）₆₀−（Ｖ−３３）₄₀−
ＰＡ１４２：−（ＡＡ）₇₀−（Ｖ−３４）₃₀−
ＰＡ１４３：−（ＡＡ）₇₀−（Ｖ−３５）₃₀−
【００９２】
ＰＡ２０１：−（ＭＡ）₇₀−（Ｖ−１）₃₀−
ＰＡ２０２：−（ＭＡ）₆₀−（Ｖ−１）₄₀−
ＰＡ２０３：−（ＭＡ）₅₀−（Ｖ−１）₅₀−
ＰＡ２０４：−（ＭＡ）₄₀−（Ｖ−１）₆₀−
ＰＡ２０５：−（ＭＡ）₆₀−（Ｖ−２）₄₀−
ＰＡ２０６：−（ＭＡ）₆₀−（Ｖ−３）₄₀−
ＰＡ２０７：−（ＭＡ）₆₀−（Ｖ−４）₄₀−
ＰＡ２０８：−（ＭＡ）₆₀−（Ｖ−５）₄₀−
ＰＡ２０９：−（ＭＡ）₄₀−（Ｖ−６）₄₀−
ＰＡ２１０：−（ＭＡ）₅₀−（Ｖ−７）₅₀−
ＰＡ２１１：−（ＭＡ）₇₀−（Ｖ−８）₃₀−
【００９３】
ＰＡ２１２：−（ＭＡ）₆₀−（Ｖ−９）₄₀−
ＰＡ２１３：−（ＭＡ）₆₀−（Ｖ−１０）₄₀−
ＰＡ２１４：−（ＭＡ）₆₀−（Ｖ−１１）₄₀−
ＰＡ２１５：−（ＭＡ）₅₀−（Ｖ−１２）₅₀−
ＰＡ２１６：−（ＭＡ）₅₀−（Ｖ−１３）₅₀−
ＰＡ２１７：−（ＭＡ）₇₀−（Ｖ−１４）₃₀−
ＰＡ２１８：−（ＭＡ）₅₀−（Ｖ−１５）₅₀−
ＰＡ２１９：−（ＭＡ）₆₀−（Ｖ−１６）₄₀−
ＰＡ２２０：−（ＭＡ）₆₀−（Ｖ−１７）₄₀−
ＰＡ２２１：−（ＭＡ）₆₀−（Ｖ−１８）₄₀−
ＰＡ２２２：−（ＭＡ）₆₀−（Ｖ−１９）₄₀−
【００９４】
ＰＡ２２３：−（ＭＡ）₇₅−（Ｖ−２０）₂₅−
ＰＡ２２４：−（ＭＡ）₆₀−（Ｖ−２０）₄₀−
ＰＡ２２５：−（ＭＡ）₇₀−（Ｖ−２１）₃₀−
ＰＡ２２６：−（ＭＡ）₈₀−（Ｖ−２２）₂₀−
ＰＡ２２７：−（ＭＡ）₇₀−（Ｖ−２２）₃₀−
ＰＡ２２８：−（ＭＡ）₆₀−（Ｖ−２２）₄₀−
ＰＡ２２９：−（ＭＡ）₇₀−（Ｖ−２３）₃₀−
ＰＡ２３０：−（ＭＡ）₇₀−（Ｖ−２４）₃₀−
ＰＡ２３１：−（ＭＡ）₈₀−（Ｖ−２５）₂₀−
ＰＡ２３２：−（ＭＡ）₇₀−（Ｖ−２５）₃₀−
ＰＡ２３３：−（ＭＡ）₆₀−（Ｖ−２５）₄₀−
【００９５】
ＰＡ２３４：−（ＭＡ）₆₀−（Ｖ−２６）₄₀−
ＰＡ２３５：−（ＭＡ）₇₀−（Ｖ−２７）₃₀−
ＰＡ２３６：−（ＭＡ）₈₀−（Ｖ−２８）₂₀−
ＰＡ２３７：−（ＭＡ）₇₀−（Ｖ−２９）₃₀−
ＰＡ２３８：−（ＭＡ）₆₀−（Ｖ−３０）₄₀−
ＰＡ２３９：−（ＭＡ）₇₀−（Ｖ−３１）₃₀−
ＰＡ２４０：−（ＭＡ）₇₀−（Ｖ−３２）₃₀−
ＰＡ２４１：−（ＭＡ）₆₀−（Ｖ−３３）₄₀−
ＰＡ２４２：−（ＭＡ）₇₀−（Ｖ−３４）₃₀−
ＰＡ２４３：−（ＭＡ）₇₀−（Ｖ−３５）₃₀−
【００９６】
式（IV）において、ｍは、１０乃至９５モル％である。
式（IV）で表される繰り返し単位と、下記式（Ｖ）で表される繰り返し単位とを含むコポリマーは、変性ポリビニルアルコールの一種である。変性ポリビニルアルコールのポリビニルアルコール部分に相当する式（IV）で表される繰り返し単位は、ケン化度が１００％である必要はない。言い換えると、変性ポリビニルアルコールは、下記式（VI）で表される酢酸ビニルに対応する繰り返し単位を含むことができる。
【００９７】
【化３０】

【００９８】
式（VI）において、ｋは、０．０１乃至２０モル％である。
以下に、好ましい変性ポリビニルアルコールの例を示す。IVは、式（IV）で表されるビニルアルコールに対応する繰り返し単位であり、VIは、式（VI）で表される酢酸ビニルに対応する繰り返し単位である。繰り返し単位の割合は、モル％である。
【００９９】
ＶＡ１０１：−（IV）₅₈−（Ｖ−１）₃₀−（VI）₁₂−
ＶＡ１０２：−（IV）₄₈−（Ｖ−１）₄₀−（VI）₁₂−
ＶＡ１０３：−（IV）₃₈−（Ｖ−１）₅₀−（VI）₁₂−
ＶＡ１０４：−（IV）₂₈−（Ｖ−１）₆₀−（VI）₁₂−
ＶＡ１０５：−（IV）₄₈−（Ｖ−２）₄₀−（VI）₁₂−
ＶＡ１０６：−（IV）₄₈−（Ｖ−３）₄₀−（VI）₁₂−
ＶＡ１０７：−（IV）₄₈−（Ｖ−４）₄₀−（VI）₁₂−
ＶＡ１０８：−（IV）₄₈−（Ｖ−５）₄₀−（VI）₁₂−
ＶＡ１０９：−（IV）₂₈−（Ｖ−６）₄₀−（VI）₁₂−
ＶＡ１１０：−（IV）₃₈−（Ｖ−７）₅₀−（VI）₁₂−
ＶＡ１１１：−（IV）₅₈−（Ｖ−８）₃₀−（VI）₁₂−
【０１００】
ＶＡ１１２：−（IV）₄₈−（Ｖ−９）₄₀−（VI）₁₂−
ＶＡ１１３：−（IV）₄₈−（Ｖ−１０）₄₀−（VI）₁₂−
ＶＡ１１４：−（IV）₄₈−（Ｖ−１１）₄₀−（VI）₁₂−
ＶＡ１１５：−（IV）₃₈−（Ｖ−１２）₅₀−（VI）₁₂−
ＶＡ１１６：−（IV）₃₈−（Ｖ−１３）₅₀−（VI）₁₂−
ＶＡ１１７：−（IV）₅₈−（Ｖ−１４）₃₀−（VI）₁₂−
ＶＡ１１８：−（IV）₃₈−（Ｖ−１５）₅₀−（VI）₁₂−
ＶＡ１１９：−（IV）₄₈−（Ｖ−１６）₄₀−（VI）₁₂−
ＶＡ１２０：−（IV）₄₈−（Ｖ−１７）₄₀−（VI）₁₂−
ＶＡ１２１：−（IV）₄₈−（Ｖ−１８）₄₀−（VI）₁₂−
ＶＡ１２２：−（IV）₄₈−（Ｖ−１９）₄₀−（VI）₁₂−
【０１０１】
ＶＡ１２３：−（IV）₆₃−（Ｖ−２０）₂₅−（VI）₁₂−
ＶＡ１２４：−（IV）₄₈−（Ｖ−２０）₄₀−（VI）₁₂−
ＶＡ１２５：−（IV）₅₈−（Ｖ−２１）₃₀−（VI）₁₂−
ＶＡ１２６：−（IV）₆₈−（Ｖ−２２）₂₀−（VI）₁₂−
ＶＡ１２７：−（IV）₅₈−（Ｖ−２２）₃₀−（VI）₁₂−
ＶＡ１２８：−（IV）₄₈−（Ｖ−２２）₄₀−（VI）₁₂−
ＶＡ１２９：−（IV）₅₈−（Ｖ−２３）₃₀−（VI）₁₂−
ＶＡ１３０：−（IV）₅₈−（Ｖ−２４）₃₀−（VI）₁₂−
ＶＡ１３１：−（IV）₆₈−（Ｖ−２５）₂₀−（VI）₁₂−
ＶＡ１３２：−（IV）₅₈−（Ｖ−２５）₃₀−（VI）₁₂−
ＶＡ１３３：−（IV）₄₈−（Ｖ−２５）₄₀−（VI）₁₂−
【０１０２】
ＶＡ１３４：−（IV）₄₈−（Ｖ−２６）₄₀−（VI）₁₂−
ＶＡ１３５：−（IV）₅₈−（Ｖ−２７）₃₀−（VI）₁₂−
ＶＡ１３６：−（IV）₆₈−（Ｖ−２８）₂₀−（VI）₁₂−
ＶＡ１３７：−（IV）₅₈−（Ｖ−２９）₃₀−（VI）₁₂−
ＶＡ１３８：−（IV）₄₈−（Ｖ−３０）₄₀−（VI）₁₂−
ＶＡ１３９：−（IV）₅₈−（Ｖ−３１）₃₀−（VI）₁₂−
ＶＡ１４０：−（IV）₅₈−（Ｖ−３２）₃₀−（VI）₁₂−
ＶＡ１４１：−（IV）₄₈−（Ｖ−３３）₄₀−（VI）₁₂−
ＶＡ１４２：−（IV）₅₈−（Ｖ−３４）₃₀−（VI）₁₂−
ＶＡ１４３：−（IV）₅₈−（Ｖ−３５）₃₀−（VI）₁₂−
【０１０３】
二種類以上のポリマーを併用してもよい。
【０１０４】
［透明支持体］
透明支持体としては、ポリマーフイルムを用いることが好ましい。透明支持体は、波長分散が小さいことが好ましい。また、透明支持体は、光学異方性が小さいことも好ましい。
支持体が透明であるとは、光透過率が８０％以上であることを意味する。波長分散が小さいとは、具体的には、Ｒｅ４００／Ｒｅ７００の比が１．２未満であることが好ましい。光学異方性が小さいとは、具体的には、面内レターデーション（Ｒｅ）が２０ｎｍ以下であることが好ましく、１０ｎｍ以下であることがさらに好ましい。
【０１０５】
長尺状の透明支持体は、ロール状または長方形のシート状の形状を有する。ロール状の透明支持体を用いて、光学異方性層を積層してから、必要な大きさに切断することが好ましい。
ポリマーフイルム支持体を形成するポリマーの例には、セルロースエステル、ポリカーボネート、ポリスルホン、ポリエーテルスルホン、ポリアクリレートおよびポリメタクリレートが含まれる。セルロースエステルが好ましく、セルロースアセテートがさらに好ましく、セルローストリアセテートが最も好ましい。ポリマーフイルムは、ソルベントキャスト法により形成することが好ましい。
透明支持体の厚さは、２０乃至５００μｍであることが好ましく、５０乃至２００μｍであることがさらに好ましい。透明支持体とその上に設けられる層（接着層、配向膜あるいは光学異方性層）との接着を改善するため、透明支持体に表面処理（例、グロー放電処理、コロナ放電処理、紫外線（ＵＶ）処理、火炎処理）を実施してもよい。透明支持体の上に、接着層（下塗り層）を設けてもよい。
【０１０６】
［円偏光板］
本発明の位相差板は、反射型液晶表示装置において使用されるλ／４板、光ディスクの書き込み用のピックアップに使用されるλ／４板、あるいは反射防止膜として利用されるλ／４板として、特に有利に用いることができる。λ／４板は、一般に直線偏光膜と組み合わせた円偏光板として使用される。よって、位相差板と直線偏光膜とを組み合わせた円偏光板として構成しておくと、容易に反射型液晶表示装置のような用途とする装置に組み込むことができる。
直線偏光膜には、ヨウ素系偏光膜、二色性染料を用いる染料系偏光膜やポリエン系偏光膜がある。ヨウ素系偏光膜および染料系偏光膜は、一般にポリビニルアルコール系フイルムを用いて製造する。直線偏光膜の透過軸は、フイルムの延伸方向に垂直な方向に相当する。直線偏光膜は、一般に両側に保護膜を有する。ただし、本発明では、透明支持体を直線偏光膜の片側の保護膜として機能させることができる。透明支持体とは別に保護膜を用いる場合は、保護膜として光学的等方性が高いセルロースエステルフイルム、特にセルローストリアセテートフイルムを用いることが好ましい。
【０１０７】
広域帯λ／４とは、具体的には、波長４５０ｎｍ、５５０ｎｍおよび６５０ｎｍで測定したレターデーション値／波長の値が、いずれも０．２０乃至０．３０の範囲内であることを意味する。レターデーション値／波長の値は、０．２１乃至０．２９の範囲内であることが好ましく、０．２２乃至０．２８の範囲内であることがより好ましく、０．２３乃至０．２７の範囲内であることがさらに好ましく、０．２４乃至０．２６の範囲内であることが最も好ましい。
【０１０８】
【実施例】
［実施例１］
（第１配向膜の形成）
厚さ１００μｍ、幅５００ｍｍ、長さ５００ｍの光学的に等方性のロール状セルローストリアセテートフイルムを透明支持体として用いた。
下記のコポリマー（ＰＡ−１３２）の希釈液を透明支持体の片面に連続塗布して、厚さ０．５μｍの第１（直交型）配向膜を形成した。次いで、透明支持体の長手方向に対し右手１６°の方向に連続的にラビング処理を実施した。
【０１０９】
【化３１】

【０１１０】
（第１光学異方性層の形成）
第１配向膜の上に、下記の組成の塗布液をバーコーターを用いて連続的に塗布、乾燥、および加熱（配向熟成）し、さらに紫外線照射して厚さ１．６μｍの第１光学的異方性層を形成した。第１光学的異方性層は、透明支持体の長手方向に対して７４°の方向に遅相軸を有していた。波長５５０ｎｍにおけるレターデーション値は２２５ｎｍであった。
【０１１１】

【０１１２】
【化３２】

【０１１３】
（第２配向膜の形成）
第１光学異方性層の上に、下記のコポリマーの希釈液を連続塗布して、厚さ０．５μｍの第２（平行型）配向膜を形成した。次いで、透明支持体の長手方向に対し左手１６°の方向（第１光学異方性層の遅相軸に対して右手５８゜の方向）に連続的にラビング処理を実施した。
【０１１４】
【化３３】

【０１１５】
（第２光学異方性層の形成）
第２配向膜の上に、下記の組成の塗布液をバーコーターを用いて連続的に塗布、乾燥、および加熱（配向熟成）し、さらに紫外線照射して厚さ０．８μｍの第２光学的異方性層を形成した。第２光学的異方性層は、透明支持体の長手方向に対して左手１６°の方向に遅相軸を有していた。波長５５０ｎｍにおけるレターデーション値は１１３ｎｍであった。
【０１１６】

【０１１７】
（位相差板の評価）
作製した位相差板に、光（測定波長は４５０ｎｍ、５５０ｎｍ、６５０ｎｍ）を照射し、通過した光の位相差（レターデーション値：Ｒｅ）を測定した。結果を第１表に示す。
【０１１８】
（円偏光板の作製）
直線偏光膜と透明保護膜とを、位相差板に貼りあわせ円偏光板を作製した。直線偏光膜の偏光軸と位相差板の長手方向との角度が９０°（直線偏光膜の偏光軸と位相差板の遅相軸との角度が４５°）になるように配置した。
作製した円偏光板を調べたところ、広い波長領域で円偏光を達成していた。
【０１１９】
［実施例２］
（第１配向膜の形成）
厚さ１００μｍ、幅５００ｍｍ、長さ５００ｍの光学的に等方性のロール状セルローストリアセテートフイルムを透明支持体として用いた。
ステロイド変性ポリアミック酸の希釈液を、透明支持体の片面上に連続塗布し、厚さ０．５μｍの第１（垂直）配向膜を形成した。次に、透明支持体の長手方向に対して右手１５゜の方向に、連続的にラビング処理を実施した。
【０１２０】
（第１光学異方性層の形成）
第１配向膜の上に、下記の組成の塗布液をバーコーターを用いて連続的に塗布、乾燥および加熱（配向熟成）し、さらに紫外線を照射して、厚さ１．６１μｍの第１光学異方性層を形成した。
第１光学異方性層は、透明支持体の長手方向に対して右手１５°の方向に遅相軸を有していた。波長５５０ｎｍにおけるレターデーション値は２２６ｎｍであった。
【０１２１】

【０１２２】
【化３４】

【０１２３】
【化３５】

【０１２４】
（第２配向膜の形成）
第１光学異方性層の上に、ステロイド変性ポリアミック酸の希釈液を連続塗布し、厚さ０．５μｍの第２（垂直）配向膜を形成した。次に、透明支持体の長手方向に対して右手７５゜の方向（第１光学異方性層の遅相軸に対し右手６０゜の方向）に、連続的にラビング処理を実施した。
【０１２５】
（第２光学異方性層の形成）
第２配向膜の上に、第１光学異方性層と同じ組成の塗布液をバーコーターを用いて連続的に塗布、乾燥および加熱（配向熟成）し、さらに紫外線を照射して、厚さ０．８０μｍの第２光学異方性層を形成した。
第２光学異方性層は、透明支持体の長手方向に対して右手７５゜の方向に遅相軸を有していた。波長５５０ｎｍにおけるレターデーション値は１１３ｎｍであった。
【０１２６】
（位相差板の評価）
作製した位相差板に、光（測定波長は４５０ｎｍ、５５０ｎｍ、６５０ｎｍ）を照射し、通過した光の位相差（レターデーション値：Ｒｅ）を測定した。結果を第１表に示す。
【０１２７】
［比較例１］
（第１配向膜の形成）
厚さ１００μｍ、幅５００ｍｍ、長さ５００ｍの光学的に等方性のロール状セルローストリアセテートフイルムを透明支持体として用いた。
ステロイド変性ポリアミック酸の希釈液を、透明支持体の片面上に連続塗布し、厚さ０．５μｍの第１（垂直）配向膜を形成した。次に、透明支持体の長手方向に対して右手１５゜の方向に、連続的にラビング処理を実施した。
【０１２８】
（第１光学異方性層の形成）
第１配向膜の上に、実施例２の第１光学異方性層と組成の塗布液をバーコーターを用いて連続的に塗布、乾燥および加熱（配向熟成）し、さらに紫外線を照射して、厚さ１．９６μｍの第１光学異方性層を形成した。
第１光学異方性層は、透明支持体の長手方向に対して右手１５°の方向に遅相軸を有していた。波長５５０ｎｍにおけるレターデーション値は２７５ｎｍであった。
【０１２９】
（第２配向膜の形成）
第１光学異方性層の上に、ステロイド変性ポリアミック酸の希釈液を連続塗布し、厚さ０．５μｍの第２（垂直）配向膜を形成した。次に、透明支持体の長手方向に対して右手７５゜の方向（第１光学異方性層の遅相軸に対し右手６０゜の方向）に、連続的にラビング処理を実施した。
【０１３０】
（第２光学異方性層の形成）
第１配向膜の上に、実施例２の第１光学異方性層と同じ組成の塗布液をバーコーターを用いて連続的に塗布、乾燥および加熱（配向熟成）し、さらに紫外線を照射して、厚さ０．９８μｍの第２光学異方性層を形成した。
第２光学異方性層は、透明支持体の長手方向に対して右手７５゜の方向に遅相軸を有していた。波長５５０ｎｍにおけるレターデーション値は１３８ｎｍであった。
【０１３１】
（位相差板の評価）
作製した位相差板に、光（測定波長は４５０ｎｍ、５５０ｎｍ、６３０ｎｍ）を照射し、通過した光の位相差（レターデーション値：Ｒｅ）を測定した。結果を第１表に示す。
【０１３２】
【表１】

【０１３３】
第１表に示される結果から明らかなように、実施例１および２で作製した位相差板は、特に短波長領域で理論的なλ／４に近い位相差を示す。
【図面の簡単な説明】
【図１】本発明の位相差板の基本的な構成を示す模式図である。
【図２】本発明の位相差板の代表的な構成を示す模式図である。
【図３】本発明の円偏光板の代表的な構成を示す模式図である。
【図４】本発明の位相差板の別の基本的な構成を示す模式図である。
【図５】本発明の位相差板の別の代表的な構成を示す模式図である。
【図６】本発明の円偏光板の別の代表的な構成を示す模式図である。
【符号の説明】
Ｓ 長尺状透明支持体
ｓ 透明支持体の長手方向
Ａ （第１）光学異方性層
ａ （第１）光学異方性層の面内の遅相軸
Ｂ 第２光学異方性層
ｂ 第２光学異方性層の面内の遅相軸
ｒ、ｒ１、ｒ２ 棒状液晶性分子
Ｐ 直線偏光膜
ｐ 直線偏光膜の偏光軸
α ａとｓとの角度
β ｂとｓとの角度
γ ａとｂとの角度[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a retardation plate having a transparent support having a longitudinal direction and an optically anisotropic layer, and a circularly polarizing plate using the same. In particular, the present invention relates to a retardation plate effective as a λ / 4 plate used for a reflective liquid crystal display device, an optical disk writing pickup, or an antireflection film.
[0002]
[Prior art]
The λ / 4 plate has a great many applications and has already been used in practice. However, even if it is referred to as a λ / 4 plate, most of them achieve λ / 4 at a specific wavelength.
JP-A-10-68816 and JP-A-10-90521 disclose retardation plates obtained by laminating two polymer films having optical anisotropy. The retardation plate described in Japanese Patent Application Laid-Open No. 10-68816 includes a quarter wavelength plate in which the phase difference of birefringent light is a quarter wavelength, and a half in which the phase difference of birefringent light is a half wavelength. The wave plates are bonded together with their optical axes intersecting. In the retardation plate described in JP-A-10-90521, at least two retardation plates having a retardation value of 160 to 320 nm are laminated so that their slow axes are not parallel or orthogonal to each other. Yes. Specifically, the retardation plate described in any of the publications is composed of a laminate of two polymer films. Both publications explain that λ / 4 can be achieved in a wide wavelength region.
[0003]
However, in the production of the phase difference plate described in JP-A-10-68816 and JP-A-10-90521, in order to adjust the optical orientation (optical axis and slow axis) of the two polymer films, It is necessary to cut the polymer film at a predetermined angle and bond the resulting chips together. If a phase difference plate is manufactured by bonding chips, the process is complicated, the quality is likely to deteriorate due to axial misalignment, the yield decreases, the cost increases, and deterioration due to contamination is likely to occur. In addition, it is difficult to strictly adjust the retardation value in a polymer film.
[0004]
Broadband λ, which is a combination of an optically anisotropic layer formed from a liquid crystalline compound and a polymer film, or a combination of two optically anisotropic layers formed from a liquid crystalline compound, compared to a method using two polymer films / 4 plate has been proposed. Japanese Patent Laid-Open Nos. 2001-4837 and 2001-21720 disclose an optically anisotropic layer having a retardation value of λ / 2 at a specific wavelength (λ) and a retardation value at the wavelength (λ). In a broadband λ / 4 plate combined with a (second) optically anisotropic layer that is λ / 4, one optically anisotropic layer is formed from liquid crystalline molecules, and the other optically anisotropic layer is a polymer film. Or it proposes forming from a liquid crystalline molecule. When at least one optically anisotropic layer is formed of a liquid crystalline compound, the retardation plate can be easily manufactured and the thickness of the retardation plate can be reduced as compared with the case of using two polymer films.
In the retardation plate described in JP-A-2001-4837, the angle between the slow axis of the optically anisotropic layer and the longitudinal direction of the transparent support is adjusted to be substantially 75 °. The circularly polarizing plate can be produced by roll-to-roll without the need to bond the cut chips.
[0005]
[Problems to be solved by the invention]
The retardation plates described in JP-A Nos. 2001-4837 and 2001-21720 are thin, and have an advantage that the retardation plate itself and the circularly polarizing plate can be produced by roll-to-roll.
However, when the inventor applied the retardation plate and the circularly polarizing plate described in each publication to a reflective liquid crystal display device, a problem was found that the black display portion was bluish.
An object of the present invention is to accurately adjust the retardation of an optically anisotropic layer formed from a liquid crystalline compound.
Another object of the present invention is to provide a retardation plate capable of realizing an accurate broadband λ / 4.
Furthermore, the objective of this invention is also providing the circularly-polarizing plate which produces exact circularly polarized light in a wide band.
[0006]
[Means for Solving the Problems]
The present invention provides the following retardation plates (1) to (4) and (7) to (10) and circular polarizing plates (5), (6), (11), and (12) below.
(1) It has an optically anisotropic layer formed from a transparent support having a longitudinal direction and a liquid crystalline compound, the retardation value at a measurement wavelength of 550 nm of the optically anisotropic layer is 180 to 240 nm, and optically anisotropic A retardation film characterized in that an angle between the slow axis in the plane of the conductive layer and the longitudinal direction of the transparent support is substantially 75 °.
(2) The retardation plate according to (1), wherein the optically anisotropic layer is a layer formed by a polymerization reaction of a liquid crystalline compound represented by the following formula (I):
(I) Q1-L1-Cy1-L2- (Cy2-L3) n-Cy3-L4-Q2
Wherein Q1 and Q2 are each independently a polymerizable group; L1 and L4 are each independently a divalent linking group; L2 and L3 are each independently a single bond or divalent Cy1, Cy2 and Cy3 are each independently a divalent cyclic group; and n is 0, 1 or 2.]
[0007]
(3) A first optical anisotropy having a transparent support having a longitudinal direction, a first optical anisotropic layer formed from a liquid crystalline compound, and a second optical anisotropic layer formed from a liquid crystalline compound. The retardation value at the measurement wavelength of 550 nm of the layer is 180 to 240 nm, the retardation value of the second optical anisotropic layer at the measurement wavelength 550 nm is 60 to 170 nm, and the in-plane retardation of the first optical anisotropic layer is The angle between the phase axis and the longitudinal direction of the transparent support is substantially 75 °, and the angle between the slow axis in the plane of the second optically anisotropic layer and the longitudinal direction of the transparent support is substantially 15 °. And the angle between the in-plane slow axis of the second optically anisotropic layer and the in-plane slow axis of the first optically anisotropic layer is substantially 60 °. Retardation plate.
(4) The retardation according to (3), wherein the first optical anisotropic layer or the second optical anisotropic layer is a layer formed by a polymerization reaction of the liquid crystalline compound represented by the formula (I). Board.
[0008]
(5) A linearly polarized light having a linearly polarizing film, a transparent support having a longitudinal direction, a first optically anisotropic layer formed from a liquid crystalline compound, and a second optically anisotropic layer formed from a liquid crystalline compound A first optical anisotropic layer is disposed between the film and the second optical anisotropic layer, and the retardation value of the first optical anisotropic layer at a measurement wavelength of 550 nm is 180 to 240 nm. The retardation value of the isotropic layer at a measurement wavelength of 550 nm is 60 to 170 nm, the polarization axis of the linearly polarizing film and the longitudinal direction of the transparent support are substantially orthogonal, and the surface of the first optically anisotropic layer The angle between the slow axis in the substrate and the longitudinal direction of the transparent support is substantially 75 °, and the angle between the slow axis in the plane of the second optically anisotropic layer and the longitudinal direction of the transparent support is substantially And the slow axis in the plane of the second optically anisotropic layer and the first Circular polarizer angle between the slow axis in the plane of the optically anisotropic layer is substantially 60 °.
(6) The retardation according to (5), wherein the first optical anisotropic layer or the second optical anisotropic layer is a layer formed by a polymerization reaction of the liquid crystalline compound represented by the formula (I). Board.
The circularly polarizing plate is preferably laminated in the order of a linearly polarizing film, a transparent support, a first optically anisotropic layer, and a second optically anisotropic layer.
[0009]
(7) It has an optically anisotropic layer formed from a transparent support having a longitudinal direction and a liquid crystalline compound, the retardation value at a measurement wavelength of 550 nm of the optically anisotropic layer is 180 to 240 nm, and optically anisotropic A phase difference plate, wherein the angle between the slow axis in the plane of the conductive layer and the longitudinal direction of the transparent support is substantially 15 °.
(8) The retardation plate according to (7), wherein the optically anisotropic layer is a layer formed by a polymerization reaction of the liquid crystalline compound represented by the formula (I).
[0010]
(9) A first optical anisotropy having a transparent support having a longitudinal direction, a first optical anisotropic layer formed from a liquid crystalline compound, and a second optical anisotropic layer formed from a liquid crystalline compound The retardation value at the measurement wavelength of 550 nm of the layer is 180 to 240 nm, the retardation value of the second optical anisotropic layer at the measurement wavelength 550 nm is 60 to 170 nm, and the in-plane retardation of the first optical anisotropic layer is The angle between the phase axis and the longitudinal direction of the transparent support is substantially 15 °, and the angle between the slow axis in the plane of the second optical anisotropic layer and the longitudinal direction of the transparent support is substantially 75. And the angle between the in-plane slow axis of the second optically anisotropic layer and the in-plane slow axis of the first optically anisotropic layer is substantially 60 °. Retardation plate.
(10) The retardation according to (9), wherein the first optical anisotropic layer or the second optical anisotropic layer is a layer formed by a polymerization reaction of the liquid crystalline compound represented by the formula (I). Board.
[0011]
(11) A linearly polarized light having a linearly polarizing film, a transparent support having a longitudinal direction, a first optically anisotropic layer formed from a liquid crystalline compound, and a second optically anisotropic layer formed from a liquid crystalline compound A first optical anisotropic layer is disposed between the film and the second optical anisotropic layer, and the retardation value of the first optical anisotropic layer at a measurement wavelength of 550 nm is 180 to 240 nm. The retardation value of the isotropic layer at a measurement wavelength of 550 nm is 60 to 170 nm, the polarization axis of the linearly polarizing film and the longitudinal direction of the transparent support are substantially orthogonal, and the surface of the first optically anisotropic layer The angle between the slow axis in the inner surface and the longitudinal direction of the transparent support is substantially 15 °, and the angle between the slow axis in the plane of the second optically anisotropic layer and the longitudinal direction of the transparent support is substantially 75 ° and an in-plane slow axis of the second optical anisotropic layer Circular polarizer angle between the slow axis in the plane of the first optically anisotropic layer is substantially 60 °.
(12) The retardation according to (11), wherein the first optical anisotropic layer or the second optical anisotropic layer is a layer formed by a polymerization reaction of the liquid crystalline compound represented by the formula (I). Board. The circularly polarizing plate is preferably laminated in the order of a linearly polarizing film, a transparent support, a first optically anisotropic layer, and a second optically anisotropic layer.
[0012]
In the present specification, “substantially 15 °”, “substantially 75 °”, “substantially 60 °”, “substantially parallel” or “substantially orthogonal” means a strict angle ± 5 It means within the range of less than °. The error from the exact angle is preferably less than 4 °, more preferably less than 3 °, even more preferably less than 2 °, and most preferably less than 1 °. Further, the “slow axis” means a direction in which the refractive index is maximized. The “polarization axis” means a direction in which the transmittance is maximum.
[0013]
【The invention's effect】
As a result of studying a retardation plate or a circularly polarizing plate using a liquid crystalline compound as an optically anisotropic layer, the present inventors have found that the wavelength dispersion of liquid crystalline molecules is large and strict λ / 4 or circularly polarized light does not occur. Turned out to be. This problem is relatively slight when a discotic liquid crystalline compound is used, but becomes significant when a rod-like liquid crystalline compound is used.
In each of the examples described in JP-A Nos. 2001-4837 and 2001-21720, a discotic liquid crystalline compound was used, so this problem was considered to be within a slight error range. However, when the present inventor used a rod-like liquid crystalline compound instead of the disc-like liquid crystalline compound for the purpose of further thinning the retardation plate and the circularly polarizing plate, the above-mentioned problems became clear. When a retardation plate or a circularly polarizing plate that does not become strict λ / 4 or circularly polarized light is applied to a reflective liquid crystal display device, the black display portion is bluish as described above.
[0014]
The present inventor further researched and adjusted an optically anisotropic layer formed from a liquid crystal compound, which has been approximated to λ / 2 at a specific wavelength, to a retardation value smaller than the conventional λ / 2. It has been found that accurate broadband λ / 4 can be realized. In the case of using a liquid crystal compound, it is possible to achieve λ / 4 in a wider band than before by adjusting the retardation in a shorter wavelength region. By realizing more accurate broadband λ / 4 and circularly polarized light than before, it was possible to eliminate blueness in the black display portion of the reflective liquid crystal display device.
And since the phase difference plate and circularly-polarizing plate according to this invention use a liquid crystalline compound, thickness is thin and manufacture is easy.
[0015]
The present invention is particularly effective when a rod-like liquid crystalline compound (particularly a compound represented by the formula (I)) is used rather than a discotic liquid crystalline compound. The optically anisotropic layer formed from a liquid crystalline compound can be made thinner than a conventional polymer film. The rod-like liquid crystalline compound can further reduce the thickness of the optically anisotropic layer than the discotic liquid crystalline compound. In general, the liquid crystalline compound is homogeneously aligned to form an optically anisotropic layer. The homogeneously oriented discotic liquid crystalline compound needs to have a certain thickness with the disc standing. On the other hand, the homogeneously oriented rod-like liquid crystalline compound is in a state where the rod is lying and can form a thin layer.
Further, according to the present invention, the alignment film is coated on the long transparent support, and is rubbed in the direction of 75 ° or 15 ° with respect to the longitudinal direction of the transparent support, and then the liquid crystal molecules are contained. An optically anisotropic layer can be formed. Thereby, the phase difference plate which can be bonded together by a linearly polarizing film and roll-to-roll is obtained. If the retardation plate and the linearly polarizing film are continuously applied in a roll state, the circularly polarizing plate can be manufactured very easily.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
[Optical properties of optically anisotropic layer]
In the prior art, the retardation value at a specific measurement wavelength is adjusted to λ / 2, that is, around 275 nm at the measurement wavelength 550 nm of the optical anisotropic layer. In the present invention, the retardation value of the optically anisotropic layer at a measurement wavelength of 550 nm is adjusted to 180 to 240 nm (180 nm or more and less than 240 nm). The retardation value of the optically anisotropic layer at a measurement wavelength of 550 nm is preferably 190 to 238 nm, more preferably 200 to 236 nm, and most preferably 210 to 234 nm.
[0017]
When the retardation plate is used as a broadband λ / 4 plate, a second optical anisotropic layer is used in addition to the (first) optical anisotropic layer. The retardation value of the second optical anisotropic layer at a measurement wavelength of 550 nm is preferably 60 to 170 nm (60 nm or more and less than 170 nm), more preferably 70 to 150 nm, and more preferably 80 to 135 nm. More preferred is 80 to 120 nm.
The retardation value (Re (B)) at the measurement wavelength 550 nm of the second optical anisotropic layer is substantially the retardation value (Re (A)) at the measurement wavelength 550 nm of the (first) optical anisotropic layer. Preferably it is half. Specifically, Re (B) and Re (A) preferably satisfy the following formula.
0.45Re (A) <Re (B) <0.55Re (A)
[0018]
The retardation value means an in-plane retardation value for light incident from the normal direction of the optically anisotropic layer. Specifically, it is a value defined by the following formula.
Retardation value (Re) = (nx−ny) × d
In the above formula, nx and ny are in-plane main refractive indexes of the optically anisotropic layer, and d is the thickness (nm) of the optically anisotropic layer.
Accordingly, the retardation value can be easily adjusted by providing an optically anisotropic layer containing liquid crystalline molecules with an appropriate thickness derived from the above relational expression on the transparent support.
[0019]
[Configuration of retardation plate and circularly polarizing plate]
FIG. 1 is a schematic diagram showing a basic configuration of the retardation plate of the present invention.
As shown in FIG. 1, the basic retardation plate is composed of a long transparent support (S) and an optically anisotropic layer (A).
The phase difference of the optically anisotropic layer (A) is adjusted to a value (180 to 240 nm at a wavelength of 550 nm) slightly smaller than λ / 2 (275 nm at a wavelength of 550 nm).
The angle (α) between the longitudinal direction (s) of the transparent support (S) and the slow axis (a) in the plane of the optically anisotropic layer (A) is 75 °.
The optically anisotropic layer (A) shown in FIG. 1 contains rod-like liquid crystalline molecules (r). The rod-like liquid crystal molecules (r) are homogeneously aligned. The major axis direction of the rod-like liquid crystal molecule (r) corresponds to the in-plane slow axis (a) of the optically anisotropic layer (A).
Instead of the rod-like liquid crystal molecules (r), disc-like liquid crystal molecules can also be used. Even when the discotic liquid crystalline molecules are used, the discotic liquid crystalline molecules are oriented homogeneously (in a state where the disc is erected). The direction of the disc surface of the discotic liquid crystalline molecule corresponds to the slow axis of the optically anisotropic layer.
[0020]
FIG. 2 is a schematic diagram showing a typical configuration of the retardation plate of the present invention.
The retardation plate shown in FIG. 2 has a second optically anisotropic layer (B) in addition to the transparent support (S) and the first optically anisotropic layer (A) shown in FIG.
Similar to FIG. 1, the phase difference of the first optically anisotropic layer (A) is adjusted to a value slightly smaller than λ / 2 (275 nm at a wavelength of 550 nm) (180 to 240 nm at a wavelength of 550 nm). The retardation of the second optical anisotropic layer (B) is adjusted to about λ / 4 (60 to 170 nm at a wavelength of 550 nm).
As in FIG. 1, the angle (α) between the longitudinal direction (s) of the transparent support (S) and the in-plane slow axis (a) of the first optically anisotropic layer (A) is 75 °. . The angle (β) between the in-plane slow axis (b) of the second optically anisotropic layer (B) and the longitudinal direction (s) of the transparent support (S) is 15 °. The angle (γ) between the in-plane slow axis (b) of the second optically anisotropic layer (B) and the in-plane slow axis (a) of the optically anisotropic layer (A) is 60 °. It is.
The first optical anisotropic layer (A) and the second optical anisotropic layer (B) shown in FIG. 2 contain rod-like liquid crystalline molecules (r1 and r2), respectively. The rod-like liquid crystal molecules (r1 and r2) are each homogeneously oriented. The major axis direction of the rod-like liquid crystal molecules (r1 and r2) corresponds to the in-plane slow axis (a and b) of the optically anisotropic layer (A and B).
In place of the rod-like liquid crystalline molecules (r1 and r2), discotic liquid crystalline molecules can also be used. Even when the discotic liquid crystalline molecules are used, the discotic liquid crystalline molecules are oriented homogeneously (in a state where the disc is erected). The direction of the disc surface of the discotic liquid crystalline molecule corresponds to the slow axis of the optically anisotropic layer.
[0021]
FIG. 3 is a schematic diagram showing a typical configuration of the circularly polarizing plate of the present invention.
The circularly polarizing plate shown in FIG. 3 is a linear polarizing film in addition to the transparent support (S), the first optical anisotropic layer (A) and the second optical anisotropic layer (B) shown in FIG. (P).
As in FIG. 2, the angle (α) between the longitudinal direction (s) of the transparent support (S) and the in-plane slow axis (a) of the first optically anisotropic layer (A) is 75 °. The angle (β) between the in-plane slow axis (b) of the second optically anisotropic layer (B) and the longitudinal direction (s) of the transparent support (S) is 15 °, and the second The angle (γ) between the in-plane slow axis (b) of the optically anisotropic layer (B) and the in-plane slow axis (a) of the first optically anisotropic layer (A) is 60 °. . Furthermore, the polarization axis (p) of the linearly polarizing film (P) and the longitudinal direction (s) of the transparent support (S) are orthogonal to each other.
The first optically anisotropic layer (A) and the second optically anisotropic layer (B) shown in FIG. 3 also contain rod-like liquid crystalline molecules (r1 and r2), respectively. The rod-like liquid crystal molecules (r1 and r2) are each homogeneously oriented. The major axis direction of the rod-like liquid crystal molecules (r1 and r2) corresponds to the in-plane slow axis (a and b) of the optically anisotropic layer (A and B).
In place of the rod-like liquid crystalline molecules (r1 and r2), discotic liquid crystalline molecules can also be used. Even when the discotic liquid crystalline molecules are used, the discotic liquid crystalline molecules are oriented homogeneously (in a state where the disc is erected). The direction of the disc surface of the discotic liquid crystalline molecule corresponds to the slow axis of the optically anisotropic layer.
[0022]
FIG. 4 is a schematic diagram showing another basic configuration of the retardation plate of the present invention.
As shown in FIG. 4, the basic retardation plate is composed of a long transparent support (S) and an optically anisotropic layer (A).
The phase difference of the optically anisotropic layer (A) is adjusted to a value (180 to 240 nm at a wavelength of 550 nm) slightly smaller than λ / 2 (275 nm at a wavelength of 550 nm).
The angle (α) between the longitudinal direction (s) of the transparent support (S) and the slow axis (a) in the plane of the optically anisotropic layer (A) is 15 °.
The optically anisotropic layer (A) shown in FIG. 4 contains rod-like liquid crystalline molecules (r). The rod-like liquid crystal molecules (r) are homogeneously aligned. The major axis direction of the rod-like liquid crystal molecule (r) corresponds to the in-plane slow axis (a) of the optically anisotropic layer (A).
Instead of the rod-like liquid crystal molecules (r), disc-like liquid crystal molecules can also be used. Even when the discotic liquid crystalline molecules are used, the discotic liquid crystalline molecules are oriented homogeneously (in a state where the disc is erected). The direction of the disc surface of the discotic liquid crystalline molecule corresponds to the slow axis of the optically anisotropic layer.
[0023]
FIG. 5 is a schematic diagram showing another typical configuration of the retardation plate of the present invention.
The phase difference plate shown in FIG. 5 has a second optical anisotropic layer (B) in addition to the transparent support (S) and the first optical anisotropic layer (A) shown in FIG.
As in FIG. 4, the phase difference of the first optically anisotropic layer (A) is adjusted to a value (180 to 240 nm at a wavelength of 550 nm) slightly smaller than λ / 2 (275 nm at a wavelength of 550 nm). The retardation of the second optical anisotropic layer (B) is adjusted to about λ / 4 (60 to 170 nm at a wavelength of 550 nm).
As in FIG. 4, the angle (α) between the longitudinal direction (s) of the transparent support (S) and the slow axis (a) in the plane of the first optically anisotropic layer (A) is 15 °. . The angle (β) between the in-plane slow axis (b) of the second optically anisotropic layer (B) and the longitudinal direction (s) of the transparent support (S) is 75 °. The angle (γ) between the in-plane slow axis (b) of the second optically anisotropic layer (B) and the in-plane slow axis (a) of the optically anisotropic layer (A) is 60 °. It is.
The first optical anisotropic layer (A) and the second optical anisotropic layer (B) shown in FIG. 5 each contain rod-like liquid crystalline molecules (r1 and r2). The rod-like liquid crystal molecules (r1 and r2) are each homogeneously oriented. The major axis direction of the rod-like liquid crystal molecules (r1 and r2) corresponds to the in-plane slow axis (a and b) of the optically anisotropic layer (A and B).
Instead of at least one rod-like liquid crystal molecule (r1 and r2), at least one disc-like liquid crystal molecule can also be used. Even when the discotic liquid crystalline molecules are used, the discotic liquid crystalline molecules are oriented homogeneously (in a state where the disc is erected). The direction of the disc surface of the discotic liquid crystalline molecule corresponds to the slow axis of the optically anisotropic layer.
[0024]
FIG. 6 is a schematic diagram showing another typical configuration of the circularly polarizing plate of the present invention.
In addition to the transparent support (S), the first optical anisotropic layer (A) and the second optical anisotropic layer (B) shown in FIG. P).
As in FIG. 5, the angle (α) between the longitudinal direction (s) of the transparent support (S) and the in-plane slow axis (a) of the first optically anisotropic layer (A) is 15 °. The angle (β) between the in-plane slow axis (f) of the second optically anisotropic layer (B) and the longitudinal direction (s) of the transparent support (S) is 75 °, and the second The angle (γ) between the in-plane slow axis (b) of the optically anisotropic layer (B) and the in-plane slow axis (a) of the first optically anisotropic layer (A) is 60 °. . Furthermore, the polarization axis (p) of the polarizing film (P) and the longitudinal direction (s) of the transparent support (S) are orthogonal to each other.
The first optical anisotropic layer (A) and the second optical anisotropic layer (B) shown in FIG. 6 also contain rod-like liquid crystalline molecules (r1 and r2), respectively. The rod-like liquid crystal molecules (r1 and r2) are each homogeneously oriented. The major axis direction of the rod-like liquid crystal molecules (r1 and r2) corresponds to the in-plane slow axis (a and b) of the optically anisotropic layer (A and B).
In place of the rod-like liquid crystalline molecules (r1 and r2), discotic liquid crystalline molecules can also be used. Even when the discotic liquid crystalline molecules are used, the discotic liquid crystalline molecules are oriented homogeneously (in a state where the disc is erected). The direction of the disc surface of the discotic liquid crystalline molecule corresponds to the slow axis of the optically anisotropic layer.
[0025]
[Optically anisotropic layer]
The optically anisotropic layer is formed from a liquid crystalline compound.
The liquid crystal compound is preferably a rod-like liquid crystal molecule or a discotic liquid crystal molecule. The liquid crystalline molecules are preferably substantially uniformly aligned, more preferably fixed in a substantially uniformly aligned state, and the liquid crystalline molecules are fixed by a polymerization reaction. Is most preferred. The orientation of the liquid crystalline molecules is adjusted so that the angle between the slow axis in the plane of the optically anisotropic layer and the longitudinal direction of the transparent support is substantially 75 ° or 15 °. The liquid crystal molecules are preferably in a homogeneous alignment.
[0026]
As rod-like liquid crystalline molecules, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. In addition to the above low-molecular liquid crystalline molecules, high-molecular liquid crystalline molecules can also be used. More preferably, the orientation of the rod-like liquid crystal molecules is fixed by polymerization. The polymerizable rod-like liquid crystal molecules are described in Makromol. Chem., 190, 2255 (1989), Advanced Materials, 5, 107 (1993). U.S. Pat. Nos. 4,683,327, 5,622,648, 5,770,107, WO95 / 22586, 95/24455, 97/00600, 98/23580, and 98/52905, JP-A-1 Nos. -272551, 6-16616, 7-110469, and 11-80081.
[0027]
A polymerizable rod-like liquid crystalline molecule represented by the following formula (I) is particularly preferable.
(I) Q1-L1-Cy1-L2- (Cy2-L3) n-Cy3-L4-Q2
[0028]
In formula (I), Q1 and Q2 are each independently a polymerizable group. The polymerization reaction of the polymerizable group is preferably addition polymerization (including ring-opening polymerization) or condensation polymerization. In other words, the polymerizable group is preferably a functional group capable of addition polymerization reaction or condensation polymerization reaction.
Examples of the polymerizable group are shown below.
[0029]
[Chemical 1]

[0030]
The polymerizable group (Q1 and Q2) is preferably an unsaturated polymerizable group (Q-1 to Q-7), an epoxy group (Q-8) or an aziridinyl group (Q-9). It is more preferably a group, and most preferably an ethylenically unsaturated polymerizable group (Q-1 to Q-6).
[0031]
In the formula (I), L1 and L4 are each independently a divalent linking group.
L 1 and L 4 are each independently selected from the group consisting of —O—, —S—, —CO—, —NR 1 —, a divalent chain aliphatic group, a divalent cyclic group, and combinations thereof. A valent linking group is preferred. R1 is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom.
The example of the bivalent coupling group which consists of a combination is shown below. The left side is coupled to Q (Q1 or Q2), and the right side is coupled to Cy (Cy1 or Cy2).
[0032]
L-1: —CO—O—divalent chain aliphatic group —O—
L-2: -CO-O-divalent chain aliphatic group -O-divalent cyclic group -CO-O-
L-3: -CO-O-divalent chain aliphatic group -O-divalent cyclic group -O-CO-
L-4: -CO-O-divalent chain aliphatic group -O-divalent cyclic group -divalent chain aliphatic group-
L-5: -CO-O-divalent chain aliphatic group -O-divalent cyclic group-
L-6: -CO-O-divalent chain aliphatic group -O-divalent cyclic group -divalent chain aliphatic group -CO-O-
L-7: -CO-O-divalent chain aliphatic group-O-divalent cyclic group-O-CO-divalent chain aliphatic group-
[0033]
The divalent chain aliphatic group means an alkylene group, a substituted alkylene group, an alkenylene group, a substituted alkenylene group, an alkynylene group or a substituted alkynylene group. An alkylene group, a substituted alkylene group, an alkenylene group and a substituted alkenylene group are preferred, and an alkylene group and an alkenylene group are more preferred.
The alkylene group may have a branch. The alkylene group preferably has 1 to 12 carbon atoms, more preferably 2 to 10 carbon atoms, and most preferably 3 to 8 carbon atoms.
The alkylene part of the substituted alkylene group is the same as the above alkylene group. Examples of the substituent of the substituted alkylene group include a halogen atom.
The alkenylene group may have a branch. The alkenylene group has preferably 2 to 12 carbon atoms, more preferably 2 to 8 carbon atoms, and most preferably 2 to 4 carbon atoms.
The alkenylene part of the substituted alkenylene group is the same as the above alkenylene group. Examples of the substituent of the substituted alkenylene group include a halogen atom.
The alkynylene group may have a branch. The number of carbon atoms in the alkynylene group is preferably 2 to 12, more preferably 2 to 8, and most preferably 2 to 4.
The alkynylene part of the substituted alkynylene group is the same as the above alkynylene group. Examples of the substituent of the substituted alkynylene group include a halogen atom.
[0034]
The definition and examples of the divalent cyclic group are the same as the definitions and examples of Cy1 to Cy3 described later.
R1 is preferably an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, more preferably an alkyl group having 1 or 2 carbon atoms or a hydrogen atom, and most preferably a hydrogen atom. .
[0035]
In formula (I), L2 or L3 each independently represents a single bond or a divalent linking group.
The divalent linking group is a divalent group selected from the group consisting of —O—, —S—, —CO—, —NR 2 —, a divalent chain aliphatic group, a divalent cyclic group, and combinations thereof. A linking group is preferred. R2 is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom.
The definition and examples of the divalent chain aliphatic group are the same as the definitions and examples of L1 and L4.
The definition and examples of the divalent cyclic group are the same as the definitions and examples of Cy1 to Cy3 described later.
R2 is preferably an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, more preferably an alkyl group having 1 or 2 carbon atoms or a hydrogen atom, and most preferably a hydrogen atom. .
[0036]
In formula (I), Cy1, Cy2 and Cy3 are each independently a divalent cyclic group.
The ring contained in the cyclic group is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring, and most preferably a 6-membered ring.
The ring contained in the cyclic group may be a condensed ring. However, it is preferable that it is a single ring rather than a condensed ring.
The ring included in the cyclic group may be an aromatic ring, an aliphatic ring, or a heterocyclic ring. Examples of the aromatic ring include a benzene ring and a naphthalene ring. Examples of the aliphatic ring include a cyclohexane ring. Examples of the heterocyclic ring include a pyridine ring and a pyrimidine ring.
[0037]
As the cyclic group having a benzene ring, 1,4-phenylene is preferable. As the cyclic group having a naphthalene ring, naphthalene-1,5-diyl and naphthalene-2,6-diyl are preferable. As the cyclic group having a pyridine ring, pyridine-2,5-diyl is preferable. The cyclic group having a pyrimidine ring is preferably pyrimidine-2,5-diyl.
The cyclic group is particularly preferably 1,4-phenylene or 1,4-cyclohexylene.
The cyclic group may have a substituent. Examples of the substituent include a halogen atom, cyano, nitro, an alkyl group having 1 to 5 carbon atoms, a halogen-substituted alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, carbon An alkylthio group having 1 to 5 atoms, an acyl group having 1 to 5 carbon atoms, an acyloxy group having 2 to 6 carbon atoms, an alkoxycarbonyl group having 2 to 6 carbon atoms, a carbamoyl, and the number of carbon atoms 2-6 alkyl-substituted carbamoyl groups and amide groups having 2-6 carbon atoms are included.
[0038]
In the formula (I), n is 0, 1 or 2. When n is 2, the two L3 and Cy2 may be different. n is preferably 1 or 2, and more preferably 1.
Examples of the polymerizable liquid crystal compound represented by the formula (I) are shown below.
[0039]
[Chemical 2]

[0040]
[Chemical 3]

[0041]
[Formula 4]

[0042]
[Chemical formula 5]

[0043]
[Chemical 6]

[0044]
[Chemical 7]

[0045]
[Chemical 8]

[0046]
[Chemical 9]

[0047]
Embedded image

[0048]
Embedded image

[0049]
Embedded image

[0050]
Embedded image

[0051]
Embedded image

[0052]
Embedded image

[0053]
Embedded image

[0054]
Discotic liquid crystalline molecules are described in various literature (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); Liquid Crystal Chemistry, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985); J. Zhang et al., J Am. Chem. Soc., Vol. 116, page 2655 (1994)). The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284.
In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. However, when the polymerizable group is directly connected to the disc-shaped core, it becomes difficult to maintain the orientation state in the polymerization reaction. Therefore, a linking group is introduced between the discotic core and the polymerizable group. Therefore, the discotic liquid crystalline molecule having a polymerizable group is preferably a compound represented by the following formula (II).
[0055]
(II) D (-LQ) n
In the formula (II), D is a discotic core, L is a divalent linking group, Q is a polymerizable group, and n is an integer of 4 to 12.
Examples of the discotic core (D) of the formula (II) are shown below. In each of the following examples, LQ (or QL) means a combination of a divalent linking group (L) and a polymerizable group (Q).
[0056]
Embedded image

[0057]
Embedded image

[0058]
Embedded image

[0059]
Embedded image

[0060]
Embedded image

[0061]
Embedded image

[0062]
Embedded image

[0063]
In the formula (II), the divalent linking group (L) is selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, —CO—, —NH—, —O—, —S—, and combinations thereof. A divalent linking group is preferred. The divalent linking group (L) is a combination of at least two divalent groups selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, -CO-, -NH-, -O-, and -S-. It is more preferably a group, and most preferably a group obtained by combining at least two divalent groups selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, -CO- and -O-. The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms. The number of carbon atoms in the arylene group is preferably 6 to 10. The alkylene group, alkenylene group and arylene group may have a substituent (eg, alkyl group, halogen atom, cyano, alkoxy group, acyloxy group).
[0064]
Examples of the divalent linking group (L) are shown below. The left side is bonded to the discotic core (D), and the right side is bonded to the polymerizable group (Q). AL represents an alkylene group or an alkenylene group, and AR represents an arylene group.
L-11: -AL-CO-O-AL-
L-12: -AL-CO-O-AL-O-
L-13: -AL-CO-O-AL-O-AL-
L-14: -AL-CO-O-AL-O-CO-
L-15: -CO-AR-O-AL-
L-16: -CO-AR-O-AL-O-
L-17: -CO-AR-O-AL-O-CO-
L-18: -CO-NH-AL-
L-19: -NH-AL-O-
L-20: -NH-AL-O-CO-
[0065]
L-21: -O-AL-
L-22: -O-AL-O-
L-23: -O-AL-O-CO-
L-24: -O-AL-O-CO-NH-AL-
L-25: -O-AL-S-AL-
L-26: -O-CO-AL-AR-O-AL-O-CO-
L-27: -O-CO-AR-O-AL-CO-
L-28: -O-CO-AR-O-AL-O-CO-
L-29: -O-CO-AR-O-AL-O-AL-O-CO-
L-30: -O-CO-AR-O-AL-O-AL-O-AL-O-CO-
L-31: -S-AL-
L-32: -S-AL-O-
L-33: -S-AL-O-CO-
L-34: -S-AL-S-AL-
L-35: -S-AR-AL-
[0066]
The polymerizable group (Q) of the formula (II) is determined according to the type of polymerization reaction. The definition and examples of the polymerizable group (Q) are the same as the definitions and examples of Q1 and Q2 in the formula (I).
[0067]
A plurality of combinations of L and Q may be different but are preferably the same. Two or more kinds of discotic liquid crystalline molecules (for example, a molecule having an asymmetric carbon atom in a divalent linking group and a molecule not having it) may be used in combination.
[0068]
The optically anisotropic layer is formed by applying a coating liquid containing liquid crystalline molecules and the following polymerization initiator and other additives on the alignment film. The proportion of liquid crystalline molecules in the optically anisotropic layer is preferably 10 to 50% by mass.
As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination. The coating liquid can be applied by a known method (eg, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).
[0069]
The aligned liquid crystal molecules are fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction of the polymerizable group (Q) introduced into the liquid crystal molecule. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).
[0070]
The amount of the photopolymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the solid content of the coating solution. It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules. Irradiation energy is 20mJ / cm ² ~ 50J / cm ² Preferably, 100 to 800 mJ / cm ² More preferably. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions. The thickness of the optically anisotropic layer is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm.
[0071]
[Alignment film]
In order to align liquid crystalline molecules, it is preferable to use an alignment film.
The alignment film is an organic compound (eg, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably a polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known. An alignment film formed by a polymer rubbing treatment is particularly preferable. The rubbing treatment is carried out by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth.
[0072]
In the present invention, rod-like liquid crystal molecules or discotic liquid crystal molecules are homogeneously aligned. However, even though the same “homogeneous” is referred to, the rod-like liquid crystal molecules and the discotic liquid crystal molecules are significantly different. Therefore, the polymer used for the alignment film needs to be determined according to the type of the liquid crystal compound (rod-like liquid crystal molecule or discotic liquid crystal molecule).
In order to align the rod-like liquid crystal molecules homogeneously (horizontal), a polymer that does not decrease the surface energy of the alignment film (ordinary alignment film polymer) is used.
In order to align the discotic liquid crystalline molecules homogeneously (vertically), a polymer that reduces the surface energy of the alignment film is used. In order to reduce the surface energy of the alignment film, it is preferable to introduce a hydrocarbon group having 10 to 100 carbon atoms into the side chain of the polymer.
[0073]
Specific types of polymers are described in various documents about liquid crystal cells (mainly rod-like liquid crystalline molecules) or optical compensation sheets (mainly discotic liquid crystalline molecules).
The thickness of the alignment film is preferably 0.01 to 5 μm, and more preferably 0.05 to 1 μm.
In addition, after aligning the liquid crystal compound of the optically anisotropic layer using the alignment film, the liquid crystal layer may be transferred onto the transparent support. The liquid crystal compound fixed in the alignment state can maintain the alignment state without an alignment film.
[0074]
In the present invention, the angle between the slow axis in the plane of the optically anisotropic layer and the longitudinal direction of the transparent support is substantially set to 75 ° or 15 °.
In a general alignment film, the rubbing direction is parallel to the slow axis direction of the optically anisotropic layer made of liquid crystalline molecules. When the angle between the slow axis in the plane of the optically anisotropic layer and the longitudinal direction of the transparent support is set to substantially 15 °, a general alignment film (parallel alignment film) is used to The rubbing treatment is preferably performed in a direction of 15 ° with respect to the longitudinal direction of the support. That is, the angle between the longitudinal direction of the transparent support and the rubbing direction is preferably as small as possible (15 ° rather than 75 °).
[0075]
On the other hand, when the angle between the slow axis in the plane of the optically anisotropic layer and the longitudinal direction of the transparent support is set to substantially 75 °, a special alignment film (orthogonal alignment film) is used. The rubbing treatment is preferably performed in a direction of 15 ° with respect to the longitudinal direction of the transparent support. When the orthogonal alignment film is used, the rubbing direction and the slow axis direction of the optically anisotropic layer made of liquid crystalline molecules can be made substantially perpendicular. As a result, the angle between the longitudinal direction of the transparent support and the rubbing direction can be set as small as possible (15 ° rather than 75 °).
[0076]
The orthogonal alignment film preferably includes a copolymer containing a repeating unit represented by the following formula (III) or (IV) and a repeating unit represented by the following formula (V).
[0077]
Embedded image

[0078]
In the formula (III), R ¹ Is a hydrogen atom (acrylic acid copolymer) or methyl (methacrylic acid copolymer).
In the formula (III), M is a proton, an alkali metal (eg, Li, Na, K) ion or an ammonium ion. The ammonium ion may be substituted with an organic group (eg, methyl, ethyl).
In the formula (III), m is 10 to 95 mol%.
[0079]
In the formula (V), R ² Is a hydrogen atom, a halogen atom or an alkyl group having 1 to 6 carbon atoms. R ² Is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom, methyl or ethyl, and most preferably a hydrogen atom or methyl.
[0080]
In the formula (V), Cy is an aliphatic ring group, an aromatic group or a heterocyclic group.
The aliphatic ring of the aliphatic ring group is preferably a 5- to 7-membered ring, more preferably a 5-membered ring or a 6-membered ring, and most preferably a 6-membered ring. Examples of the aliphatic ring include a cyclohexane ring, a cyclohexene ring, and a bicyclo [2.2.1] hept-2-ene ring. Another aliphatic ring, aromatic ring or heterocyclic ring may be condensed with the aliphatic ring.
Examples of the aromatic ring of the aromatic group include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a pyrene ring and a naphthacene ring. An aliphatic ring or a heterocyclic ring may be condensed with the aromatic ring.
The heterocyclic ring of the heterocyclic group is preferably a 5- to 7-membered ring, more preferably a 5-membered ring or a 6-membered ring. The heterocycle preferably has aromaticity. Aromatic heterocycles are generally unsaturated and preferably have the most double bonds. Examples of heterocyclic rings include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, pyran ring, pyridine ring, pyridazine ring, pyrimidine ring and pyrazine ring Is included. Another heterocyclic ring, an aliphatic ring or an aromatic ring may be condensed with the heterocyclic ring.
[0081]
The aliphatic ring group, aromatic group and heterocyclic group may have a substituent. Examples of the substituent include an alkyl group (eg, methyl, ethyl, t-butyl), a substituted alkyl group (eg, chloromethyl, hydroxymethyl, trimethylammonio chloride), an alkoxy group (eg, methoxy), a halogen atom ( F, Cl, Br), carboxyl, acyl group (eg, formyl), amino, sulfo, aryl group (eg, phenyl), aryloxy group (eg, phenoxy) and oxo.
In the formula (V), n is 90 to 5 mol%.
Examples of the repeating unit represented by the formula (V) are shown below.
[0082]
Embedded image

[0083]
Embedded image

[0084]
Embedded image

[0085]
Embedded image

[0086]
Embedded image

[0087]
Examples of a copolymer containing a repeating unit represented by the following formula (III) and a repeating unit represented by the following formula (V), that is, an acrylic acid copolymer or a methacrylic acid copolymer are shown below. AA is a repeating unit derived from acrylic acid, and MA is a repeating unit derived from methacrylic acid. The ratio of the repeating unit is mol%.
[0088]
PA101:-(AA) ₇₀ -(V-1) ₃₀ −
PA102:-(AA) ₆₀ -(V-1) ₄₀ −
PA103:-(AA) ₅₀ -(V-1) ₅₀ −
PA104:-(AA) ₄₀ -(V-1) ₆₀ −
PA105:-(AA) ₆₀ -(V-2) ₄₀ −
PA106:-(AA) ₆₀ -(V-3) ₄₀ −
PA107:-(AA) ₆₀ -(V-4) ₄₀ −
PA108:-(AA) ₆₀ -(V-5) ₄₀ −
PA109:-(AA) ₄₀ -(V-6) ₄₀ −
PA110:-(AA) ₅₀ -(V-7) ₅₀ −
PA111 :-( AA) ₇₀ -(V-8) ₃₀ −
[0089]
PA112:-(AA) ₆₀ -(V-9) ₄₀ −
PA113:-(AA) ₆₀ -(V-10) ₄₀ −
PA114:-(AA) ₆₀ -(V-11) ₄₀ −
PA115:-(AA) ₅₀ -(V-12) ₅₀ −
PA116 :-( AA) ₅₀ -(V-13) ₅₀ −
PA117:-(AA) ₇₀ -(V-14) ₃₀ −
PA118:-(AA) ₅₀ -(V-15) ₅₀ −
PA119:-(AA) ₆₀ -(V-16) ₄₀ −
PA120:-(AA) ₆₀ -(V-17) ₄₀ −
PA121 :-( AA) ₆₀ -(V-18) ₄₀ −
PA122:-(AA) ₆₀ -(V-19) ₄₀ −
[0090]
PA123:-(AA) ₇₅ -(V-20) _{twenty five} −
PA124:-(AA) ₆₀ -(V-20) ₄₀ −
PA125:-(AA) ₇₀ -(V-21) ₃₀ −
PA126:-(AA) ₈₀ -(V-22) ₂₀ −
PA127:-(AA) ₇₀ -(V-22) ₃₀ −
PA128:-(AA) ₆₀ -(V-22) ₄₀ −
PA129:-(AA) ₇₀ -(V-23) ₃₀ −
PA130:-(AA) ₇₀ -(V-24) ₃₀ −
PA131:-(AA) ₈₀ -(V-25) ₂₀ −
PA132:-(AA) ₇₀ -(V-25) ₃₀ −
PA133:-(AA) ₆₀ -(V-25) ₄₀ −
[0091]
PA134:-(AA) ₆₀ -(V-26) ₄₀ −
PA135:-(AA) ₇₀ -(V-27) ₃₀ −
PA136:-(AA) ₈₀ -(V-28) ₂₀ −
PA137:-(AA) ₇₀ -(V-29) ₃₀ −
PA138:-(AA) ₆₀ -(V-30) ₄₀ −
PA139:-(AA) ₇₀ -(V-31) ₃₀ −
PA140:-(AA) ₇₀ -(V-32) ₃₀ −
PA141 :-( AA) ₆₀ -(V-33) ₄₀ −
PA142:-(AA) ₇₀ -(V-34) ₃₀ −
PA143:-(AA) ₇₀ -(V-35) ₃₀ −
[0092]
PA201 :-( MA) ₇₀ -(V-1) ₃₀ −
PA202:-(MA) ₆₀ -(V-1) ₄₀ −
PA203:-(MA) ₅₀ -(V-1) ₅₀ −
PA204:-(MA) ₄₀ -(V-1) ₆₀ −
PA205:-(MA) ₆₀ -(V-2) ₄₀ −
PA206:-(MA) ₆₀ -(V-3) ₄₀ −
PA207:-(MA) ₆₀ -(V-4) ₄₀ −
PA208:-(MA) ₆₀ -(V-5) ₄₀ −
PA209:-(MA) ₄₀ -(V-6) ₄₀ −
PA210:-(MA) ₅₀ -(V-7) ₅₀ −
PA211:-(MA) ₇₀ -(V-8) ₃₀ −
[0093]
PA212:-(MA) ₆₀ -(V-9) ₄₀ −
PA213:-(MA) ₆₀ -(V-10) ₄₀ −
PA214:-(MA) ₆₀ -(V-11) ₄₀ −
PA215:-(MA) ₅₀ -(V-12) ₅₀ −
PA216:-(MA) ₅₀ -(V-13) ₅₀ −
PA217:-(MA) ₇₀ -(V-14) ₃₀ −
PA218:-(MA) ₅₀ -(V-15) ₅₀ −
PA219:-(MA) ₆₀ -(V-16) ₄₀ −
PA220:-(MA) ₆₀ -(V-17) ₄₀ −
PA221:-(MA) ₆₀ -(V-18) ₄₀ −
PA222:-(MA) ₆₀ -(V-19) ₄₀ −
[0094]
PA223:-(MA) ₇₅ -(V-20) _{twenty five} −
PA224:-(MA) ₆₀ -(V-20) ₄₀ −
PA225:-(MA) ₇₀ -(V-21) ₃₀ −
PA226:-(MA) ₈₀ -(V-22) ₂₀ −
PA227:-(MA) ₇₀ -(V-22) ₃₀ −
PA228:-(MA) ₆₀ -(V-22) ₄₀ −
PA229:-(MA) ₇₀ -(V-23) ₃₀ −
PA230:-(MA) ₇₀ -(V-24) ₃₀ −
PA231:-(MA) ₈₀ -(V-25) ₂₀ −
PA232:-(MA) ₇₀ -(V-25) ₃₀ −
PA233:-(MA) ₆₀ -(V-25) ₄₀ −
[0095]
PA234:-(MA) ₆₀ -(V-26) ₄₀ −
PA235:-(MA) ₇₀ -(V-27) ₃₀ −
PA236:-(MA) ₈₀ -(V-28) ₂₀ −
PA237:-(MA) ₇₀ -(V-29) ₃₀ −
PA238:-(MA) ₆₀ -(V-30) ₄₀ −
PA239:-(MA) ₇₀ -(V-31) ₃₀ −
PA240:-(MA) ₇₀ -(V-32) ₃₀ −
PA241:-(MA) ₆₀ -(V-33) ₄₀ −
PA242:-(MA) ₇₀ -(V-34) ₃₀ −
PA243:-(MA) ₇₀ -(V-35) ₃₀ −
[0096]
In the formula (IV), m is 10 to 95 mol%.
A copolymer containing a repeating unit represented by the formula (IV) and a repeating unit represented by the following formula (V) is a kind of modified polyvinyl alcohol. The repeating unit represented by the formula (IV) corresponding to the polyvinyl alcohol part of the modified polyvinyl alcohol does not need to have a saponification degree of 100%. In other words, the modified polyvinyl alcohol can include a repeating unit corresponding to vinyl acetate represented by the following formula (VI).
[0097]
Embedded image

[0098]
In the formula (VI), k is 0.01 to 20 mol%.
Examples of preferable modified polyvinyl alcohol are shown below. IV is a repeating unit corresponding to the vinyl alcohol represented by the formula (IV), and VI is a repeating unit corresponding to the vinyl acetate represented by the formula (VI). The ratio of the repeating unit is mol%.
[0099]
VA101 :-( IV) ₅₈ -(V-1) ₃₀ -(VI) ₁₂ −
VA102:-(IV) ₄₈ -(V-1) ₄₀ -(VI) ₁₂ −
VA103 :-( IV) ₃₈ -(V-1) ₅₀ -(VI) ₁₂ −
VA104:-(IV) ₂₈ -(V-1) ₆₀ -(VI) ₁₂ −
VA105:-(IV) ₄₈ -(V-2) ₄₀ -(VI) ₁₂ −
VA106 :-( IV) ₄₈ -(V-3) ₄₀ -(VI) ₁₂ −
VA107:-(IV) ₄₈ -(V-4) ₄₀ -(VI) ₁₂ −
VA108:-(IV) ₄₈ -(V-5) ₄₀ -(VI) ₁₂ −
VA109:-(IV) ₂₈ -(V-6) ₄₀ -(VI) ₁₂ −
VA110 :-( IV) ₃₈ -(V-7) ₅₀ -(VI) ₁₂ −
VA111 :-( IV) ₅₈ -(V-8) ₃₀ -(VI) ₁₂ −
[0100]
VA112 :-( IV) ₄₈ -(V-9) ₄₀ -(VI) ₁₂ −
VA113:-(IV) ₄₈ -(V-10) ₄₀ -(VI) ₁₂ −
VA114 :-( IV) ₄₈ -(V-11) ₄₀ -(VI) ₁₂ −
VA115 :-( IV) ₃₈ -(V-12) ₅₀ -(VI) ₁₂ −
VA116 :-( IV) ₃₈ -(V-13) ₅₀ -(VI) ₁₂ −
VA117:-(IV) ₅₈ -(V-14) ₃₀ -(VI) ₁₂ −
VA118:-(IV) ₃₈ -(V-15) ₅₀ -(VI) ₁₂ −
VA119:-(IV) ₄₈ -(V-16) ₄₀ -(VI) ₁₂ −
VA120 :-( IV) ₄₈ -(V-17) ₄₀ -(VI) ₁₂ −
VA121 :-( IV) ₄₈ -(V-18) ₄₀ -(VI) ₁₂ −
VA122:-(IV) ₄₈ -(V-19) ₄₀ -(VI) ₁₂ −
[0101]
VA123 :-( IV) ₆₃ -(V-20) _{twenty five} -(VI) ₁₂ −
VA124:-(IV) ₄₈ -(V-20) ₄₀ -(VI) ₁₂ −
VA125 :-( IV) ₅₈ -(V-21) ₃₀ -(VI) ₁₂ −
VA126:-(IV) ₆₈ -(V-22) ₂₀ -(VI) ₁₂ −
VA127:-(IV) ₅₈ -(V-22) ₃₀ -(VI) ₁₂ −
VA128 :-( IV) ₄₈ -(V-22) ₄₀ -(VI) ₁₂ −
VA129:-(IV) ₅₈ -(V-23) ₃₀ -(VI) ₁₂ −
VA130 :-( IV) ₅₈ -(V-24) ₃₀ -(VI) ₁₂ −
VA131:-(IV) ₆₈ -(V-25) ₂₀ -(VI) ₁₂ −
VA132:-(IV) ₅₈ -(V-25) ₃₀ -(VI) ₁₂ −
VA133 :-( IV) ₄₈ -(V-25) ₄₀ -(VI) ₁₂ −
[0102]
VA134:-(IV) ₄₈ -(V-26) ₄₀ -(VI) ₁₂ −
VA135 :-( IV) ₅₈ -(V-27) ₃₀ -(VI) ₁₂ −
VA136:-(IV) ₆₈ -(V-28) ₂₀ -(VI) ₁₂ −
VA137:-(IV) ₅₈ -(V-29) ₃₀ -(VI) ₁₂ −
VA138:-(IV) ₄₈ -(V-30) ₄₀ -(VI) ₁₂ −
VA139:-(IV) ₅₈ -(V-31) ₃₀ -(VI) ₁₂ −
VA140 :-( IV) ₅₈ -(V-32) ₃₀ -(VI) ₁₂ −
VA141 :-( IV) ₄₈ -(V-33) ₄₀ -(VI) ₁₂ −
VA142:-(IV) ₅₈ -(V-34) ₃₀ -(VI) ₁₂ −
VA143:-(IV) ₅₈ -(V-35) ₃₀ -(VI) ₁₂ −
[0103]
Two or more kinds of polymers may be used in combination.
[0104]
[Transparent support]
A polymer film is preferably used as the transparent support. The transparent support preferably has a small wavelength dispersion. The transparent support preferably has a small optical anisotropy.
That the support is transparent means that the light transmittance is 80% or more. Specifically, the small chromatic dispersion means that the ratio of Re400 / Re700 is preferably less than 1.2. Specifically, the small optical anisotropy means that in-plane retardation (Re) is preferably 20 nm or less, and more preferably 10 nm or less.
[0105]
The long transparent support has a roll-like or rectangular sheet-like shape. It is preferable to laminate the optically anisotropic layer using a roll-shaped transparent support and then cut it into a required size.
Examples of the polymer forming the polymer film support include cellulose ester, polycarbonate, polysulfone, polyethersulfone, polyacrylate and polymethacrylate. Cellulose esters are preferred, cellulose acetate is more preferred, and cellulose triacetate is most preferred. The polymer film is preferably formed by a solvent cast method.
The thickness of the transparent support is preferably 20 to 500 μm, and more preferably 50 to 200 μm. In order to improve the adhesion between the transparent support and the layer (adhesive layer, alignment film or optically anisotropic layer) provided on the transparent support, surface treatment (eg, glow discharge treatment, corona discharge treatment, ultraviolet light ( UV) treatment, flame treatment). An adhesive layer (undercoat layer) may be provided on the transparent support.
[0106]
[Circularly polarizing plate]
The retardation plate of the present invention is a λ / 4 plate used in a reflective liquid crystal display device, a λ / 4 plate used for a pickup for writing on an optical disk, or a λ / 4 plate used as an antireflection film. Can be used particularly advantageously. The λ / 4 plate is generally used as a circularly polarizing plate combined with a linear polarizing film. Therefore, if it is configured as a circularly polarizing plate in which a retardation plate and a linear polarizing film are combined, it can be easily incorporated into a device for use such as a reflective liquid crystal display device.
Examples of the linear polarizing film include an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film. The iodine polarizing film and the dye polarizing film are generally manufactured using a polyvinyl alcohol film. The transmission axis of the linear polarizing film corresponds to a direction perpendicular to the film stretching direction. The linear polarizing film generally has a protective film on both sides. However, in the present invention, the transparent support can function as a protective film on one side of the linear polarizing film. When a protective film is used separately from the transparent support, it is preferable to use a cellulose ester film having a high optical isotropy, particularly a cellulose triacetate film, as the protective film.
[0107]
Specifically, the broad band λ / 4 means that the retardation value / wavelength value measured at wavelengths of 450 nm, 550 nm, and 650 nm are both in the range of 0.20 to 0.30. The retardation value / wavelength value is preferably in the range of 0.21 to 0.29, more preferably in the range of 0.22 to 0.28, and 0.23 to 0.27. More preferably, it is within the range, and most preferably within the range of 0.24 to 0.26.
[0108]
【Example】
[Example 1]
(Formation of first alignment film)
An optically isotropic roll cellulose triacetate film having a thickness of 100 μm, a width of 500 mm, and a length of 500 m was used as a transparent support.
The following copolymer (PA-132) dilution was continuously applied to one side of the transparent support to form a first (orthogonal) alignment film having a thickness of 0.5 μm. Next, rubbing treatment was continuously performed in the direction of 16 ° to the right hand with respect to the longitudinal direction of the transparent support.
[0109]
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[0110]
(Formation of first optically anisotropic layer)
On the first alignment film, a coating solution having the following composition is continuously applied using a bar coater, dried and heated (alignment aging), and further irradiated with ultraviolet rays to form a first optical film having a thickness of 1.6 μm. An anisotropic layer was formed. The first optically anisotropic layer had a slow axis in the direction of 74 ° with respect to the longitudinal direction of the transparent support. The retardation value at a wavelength of 550 nm was 225 nm.
[0111]

[0112]
Embedded image

[0113]
(Formation of second alignment film)
On the first optically anisotropic layer, a dilution solution of the following copolymer was continuously applied to form a second (parallel type) alignment film having a thickness of 0.5 μm. Next, rubbing treatment was continuously performed in a direction of 16 ° to the left hand with respect to the longitudinal direction of the transparent support (a direction of 58 ° to the right hand with respect to the slow axis of the first optically anisotropic layer).
[0114]
Embedded image

[0115]
(Formation of second optically anisotropic layer)
On the second alignment film, a coating solution having the following composition is continuously applied using a bar coater, dried and heated (alignment aging), and further irradiated with ultraviolet rays to form a second optical film having a thickness of 0.8 μm. An anisotropic layer was formed. The second optically anisotropic layer had a slow axis in the direction of 16 ° to the left with respect to the longitudinal direction of the transparent support. The retardation value at a wavelength of 550 nm was 113 nm.
[0116]

[0117]
(Evaluation of retardation plate)
The prepared retardation plate was irradiated with light (measurement wavelengths were 450 nm, 550 nm, and 650 nm), and the phase difference (retardation value: Re) of the passed light was measured. The results are shown in Table 1.
[0118]
(Production of circularly polarizing plate)
A linearly polarizing film and a transparent protective film were bonded to a retardation plate to produce a circularly polarizing plate. They were arranged so that the angle between the polarization axis of the linear polarizing film and the longitudinal direction of the retardation plate was 90 ° (the angle between the polarization axis of the linear polarizing film and the slow axis of the retardation plate was 45 °).
When the produced circularly polarizing plate was examined, circularly polarized light was achieved in a wide wavelength region.
[0119]
[Example 2]
(Formation of first alignment film)
An optically isotropic roll cellulose triacetate film having a thickness of 100 μm, a width of 500 mm, and a length of 500 m was used as a transparent support.
A diluted solution of steroid-modified polyamic acid was continuously applied on one side of the transparent support to form a first (vertical) alignment film having a thickness of 0.5 μm. Next, a rubbing treatment was continuously performed in the direction of 15 ° to the right hand with respect to the longitudinal direction of the transparent support.
[0120]
(Formation of first optically anisotropic layer)
On the first alignment film, a coating solution having the following composition is continuously applied using a bar coater, dried and heated (alignment aging), and further irradiated with ultraviolet rays to form a first optical film having a thickness of 1.61 μm. An anisotropic layer was formed.
The first optically anisotropic layer had a slow axis in the direction of 15 ° to the right with respect to the longitudinal direction of the transparent support. The retardation value at a wavelength of 550 nm was 226 nm.
[0121]

[0122]
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[0123]
Embedded image

[0124]
(Formation of second alignment film)
On the first optical anisotropic layer, a diluted solution of steroid-modified polyamic acid was continuously applied to form a second (vertical) alignment film having a thickness of 0.5 μm. Next, a rubbing treatment was continuously performed in a direction of 75 ° to the right of the longitudinal direction of the transparent support (a direction of 60 ° to the right of the slow axis of the first optically anisotropic layer).
[0125]
(Formation of second optically anisotropic layer)
On the second alignment film, a coating solution having the same composition as the first optically anisotropic layer is continuously applied using a bar coater, dried and heated (alignment aging), and further irradiated with ultraviolet rays to obtain a thickness. A 0.80 μm second optically anisotropic layer was formed.
The second optically anisotropic layer had a slow axis in the direction of 75 ° to the right with respect to the longitudinal direction of the transparent support. The retardation value at a wavelength of 550 nm was 113 nm.
[0126]
(Evaluation of retardation plate)
The prepared retardation plate was irradiated with light (measurement wavelengths were 450 nm, 550 nm, and 650 nm), and the phase difference (retardation value: Re) of the passed light was measured. The results are shown in Table 1.
[0127]
[Comparative Example 1]
(Formation of first alignment film)
An optically isotropic roll cellulose triacetate film having a thickness of 100 μm, a width of 500 mm, and a length of 500 m was used as a transparent support.
A diluted solution of steroid-modified polyamic acid was continuously applied on one side of the transparent support to form a first (vertical) alignment film having a thickness of 0.5 μm. Next, a rubbing treatment was continuously performed in the direction of 15 ° to the right hand with respect to the longitudinal direction of the transparent support.
[0128]
(Formation of first optically anisotropic layer)
On the first alignment film, the coating solution of the composition of the first optically anisotropic layer and the composition of Example 2 is continuously applied using a bar coater, dried and heated (alignment aging), and further irradiated with ultraviolet rays. A first optically anisotropic layer having a thickness of 1.96 μm was formed.
The first optically anisotropic layer had a slow axis in the direction of 15 ° to the right with respect to the longitudinal direction of the transparent support. The retardation value at a wavelength of 550 nm was 275 nm.
[0129]
(Formation of second alignment film)
On the first optical anisotropic layer, a diluted solution of steroid-modified polyamic acid was continuously applied to form a second (vertical) alignment film having a thickness of 0.5 μm. Next, a rubbing treatment was continuously performed in a direction of 75 ° to the right of the longitudinal direction of the transparent support (a direction of 60 ° to the right of the slow axis of the first optically anisotropic layer).
[0130]
(Formation of second optically anisotropic layer)
On the first alignment film, a coating solution having the same composition as that of the first optically anisotropic layer of Example 2 is continuously applied using a bar coater, dried and heated (alignment aging), and further irradiated with ultraviolet rays. Thus, a second optically anisotropic layer having a thickness of 0.98 μm was formed.
The second optically anisotropic layer had a slow axis in the direction of 75 ° to the right with respect to the longitudinal direction of the transparent support. The retardation value at a wavelength of 550 nm was 138 nm.
[0131]
(Evaluation of retardation plate)
The prepared retardation plate was irradiated with light (measurement wavelengths were 450 nm, 550 nm, and 630 nm), and the phase difference (retardation value: Re) of the passed light was measured. The results are shown in Table 1.
[0132]
[Table 1]

[0133]
As is apparent from the results shown in Table 1, the retardation plates produced in Examples 1 and 2 exhibit a retardation close to the theoretical λ / 4, particularly in the short wavelength region.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a basic configuration of a retardation plate of the present invention.
FIG. 2 is a schematic diagram showing a typical configuration of a retardation plate of the present invention.
FIG. 3 is a schematic diagram showing a typical configuration of a circularly polarizing plate of the present invention.
FIG. 4 is a schematic diagram showing another basic configuration of the retardation plate of the present invention.
FIG. 5 is a schematic diagram showing another typical configuration of the retardation film of the present invention.
FIG. 6 is a schematic diagram showing another typical configuration of the circularly polarizing plate of the present invention.
[Explanation of symbols]
S Long transparent support
s Longitudinal direction of transparent support
A (First) Optically anisotropic layer
a (First) In-plane slow axis of optically anisotropic layer
B Second optically anisotropic layer
b In-plane slow axis of the second optical anisotropic layer
r, r1, r2 Rod-like liquid crystalline molecules
P Linearly polarizing film
p Polarization axis of linear polarizing film
α Angle between a and s
angle between β b and s
γ Angle between a and b

Claims (7)

Transparent support having a longitudinal direction, the first optically anisotropic layer formed from liquid crystal compound and a second optically anisotropic layer formed from liquid crystal compound, the measurement of the first optical anisotropic layer The retardation value at a wavelength of 550 nm is 180 to 240 nm, the measurement value of the second optically anisotropic layer is 60 to 170 nm, and the in-plane slow axis of the first optically anisotropic layer is angle between the longitudinal direction of the transparent support Ri substantially 75 ° or 15 ゜Dea, angle between the longitudinal direction of the slow axes thereof and a layer plane of the second optical anisotropic layer are substantially 15 ° or 75 °, and the angle between the slow axis in the plane of the second optical anisotropic layer and the slow axis in the plane of the first optical anisotropic layer is substantially 60 °. A phase difference plate. The retardation plate according to claim 1, wherein the retardation value of the first optically anisotropic layer at a measurement wavelength of 550 nm is 210 to 234 nm . The retardation plate according to claim 1, wherein the retardation value of the second optically anisotropic layer at a measurement wavelength of 550 nm is 80 to 120 nm .   The phase difference plate according to claim 1, wherein the first optical anisotropic layer or the second optical anisotropic layer is a layer formed from rod-like liquid crystalline molecules.   The retardation plate according to claim 4, wherein the first optical anisotropic layer and the second optical anisotropic layer are layers formed from rod-like liquid crystalline molecules.   The retardation plate according to claim 4, wherein the first optical anisotropic layer or the second optical anisotropic layer is a layer formed by a polymerization reaction of rod-like liquid crystalline molecules represented by the following formula (I):
(I) Q1-L1-Cy1-L2- (Cy2-L3) n-Cy3-L4-Q2
Wherein Q1 and Q2 are each independently a polymerizable group; L1 and L4 are each independently a divalent linking group; L2 and L3 are each independently a single bond or divalent Cy1, Cy2 and Cy3 are each independently a divalent cyclic group; and n is 0, 1 or 2.]   A linearly polarizing film, a transparent support having a longitudinal direction, a first optically anisotropic layer formed from a liquid crystalline compound, and a second optically anisotropic layer formed from a liquid crystalline compound; A first optical anisotropic layer is disposed between the two optical anisotropic layers, the retardation value of the first optical anisotropic layer at a measurement wavelength of 550 nm is 180 to 240 nm, and the second optical anisotropic layer The retardation value at a measurement wavelength of 550 nm is 60 to 170 nm, the polarization axis of the linearly polarizing film is substantially perpendicular to the longitudinal direction of the transparent support, and the in-plane retardation of the first optically anisotropic layer is The angle between the phase axis and the longitudinal direction of the transparent support is substantially 75 ° or 15 °, and the angle between the slow axis in the plane of the second optically anisotropic layer and the longitudinal direction of the transparent support is substantially 15 ° or 75 ° and the surface of the second optically anisotropic layer Circular polarizer angle between the slow axis of the slow axis and the plane of the first optically anisotropic layer is substantially 60 °.

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