JP2004206038A - Optical compensating film, angle-of-view compensating polarizing plate, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical compensating film having an excellent angle-of-view compensating function to make a liquid crystal display device thin and to provide an angle-of-view compensating film, a polarizing plate, and a liquid crystal display device which have improved production yield and reworkability. <P>SOLUTION: The optical compensating film is a cellulose ester film having 10 to 70 μm thickness and satisfies conditions of 0.1≤tanδ(md)≤2.0, 0.1≤tanδ(td)≤2.0, and tanδ(md)>tanδ(td) wherein tanδ(md) and tanδ(td) are peak values of tanδin the lengthwise direction and the width direction of the film respectively, and satisfies conditions that Ro given by Ro=(nx-ny)×d is 20 to 70 nm and Rt given by ä(nx+ny)/2-nz}×d is 70 to 400 nm wherein nx, ny, nz, and d are; the refractive index in the direction of a phase lagging axis in the film plane; the refractive index in the direction of a phase advancing axis in the film plane; the refractive index in the perpendicular direction of the film; and the thickness of the film respectively. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

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更に、本発明に係わる芳香族環を少なくとも二つ有し、且つ少なくとも二つの芳香族環が平面構造を有する化合物は、上記の他に下記一般式（１）で表されるトリフェニレン環を有する化合物も好ましく用いられる。
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一般式（１）中、Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４、Ｒ_５及びＲ_６は、それぞれ独立に、水素原子、ハロゲン原子、ニトロ、スルホ、脂肪族基、芳香族基、複素環基、−Ｏ−Ｒ_１１、−Ｓ−Ｒ_１２、−ＣＯ−Ｒ_１３、−Ｏ−ＣＯ−Ｒ_１４、−ＣＯ−Ｏ−Ｒ_１５、−Ｏ−ＣＯ−Ｏ−Ｒ_１６、−ＮＲ_１７Ｒ_１８、−ＣＯ−ＮＲ_１９Ｒ_２０、−ＮＲ_２１−ＣＯ−Ｒ_２２、−Ｏ−ＣＯ−ＮＲ_２３Ｒ_２４、−ＳｉＲ_２５Ｒ_２６Ｒ_２７、−Ｏ−ＳｉＲ_２８Ｒ_２９Ｒ_３０、−Ｓ−ＣＯ−Ｒ_３１、−Ｏ−ＳＯ_２−Ｒ_３２、−ＳＯ−Ｒ_３３、−ＮＲ_３４−ＣＯ−Ｏ−Ｒ_３５、−ＳＯ_２−Ｒ_３６または−ＮＲ_３７−ＣＯ−ＮＲ_３８Ｒ_３９であって、Ｒ_１１、Ｒ_１２、Ｒ_１３、Ｒ_１４、Ｒ_１５、Ｒ_１６、Ｒ_１７、Ｒ_１８、Ｒ_１９、Ｒ_２０、Ｒ_２１、Ｒ_２２、Ｒ_２３、Ｒ_２４、Ｒ_２５、Ｒ_２６、Ｒ_２７、Ｒ_２８、Ｒ_２９、Ｒ_３０、Ｒ_３１、Ｒ_３２、Ｒ_３３、Ｒ_３４、Ｒ_３５、Ｒ_３６、Ｒ_３７、Ｒ_３８及びＲ_３９は、それぞれ独立に、水素原子、脂肪族基、芳香族基または複素環基であり；そして、Ｒ_１とＲ_２、Ｒ_３とＲ_４またはＲ_５とＲ_６は、互いに結合して環を形成してもよい。
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Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４、Ｒ_５及びＲ_６は、−Ｏ−Ｒ_１１、−Ｓ−Ｒ_１２、−Ｏ−ＣＯ−Ｒ_１４、−Ｏ−ＣＯ−Ｏ−Ｒ_１６、−ＮＲ_１７Ｒ_１８、−ＮＲ_２１−ＣＯ−Ｒ_２２または−Ｏ−ＣＯ−ＮＲ_２３Ｒ_２４であることが好ましく、−Ｏ−Ｒ_１１、−Ｓ−Ｒ_１２、−Ｏ−ＣＯ−Ｒ_１４、−Ｏ−ＣＯ−Ｏ−Ｒ_１６または−Ｏ−ＣＯ−ＮＲ_２３Ｒ_２４であることがより好ましく、−Ｏ−Ｒ_１１または−Ｏ−ＣＯ−Ｒ_１４であることがさらに好ましく、−Ｏ−ＣＯ−Ｒ_１４であることが最も好ましい。
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Ｒ_１１、Ｒ_１２、Ｒ_１３、Ｒ_１４、Ｒ_１５、Ｒ_１６、Ｒ_１７、Ｒ_１８、Ｒ_１９、Ｒ_２０、Ｒ_２１、Ｒ_２２、Ｒ_２３、Ｒ_２４、Ｒ_２５、Ｒ_２６、Ｒ_２７、Ｒ_２８、Ｒ_２９、Ｒ_３０、Ｒ_３１、Ｒ_３２、Ｒ_３３、Ｒ_３４、Ｒ_３５、Ｒ_３６、Ｒ_３７、Ｒ_３８及びＲ_３９は、水素原子、脂肪族基または芳香族基であることが好ましい。−Ｏ−ＣＯ−Ｒ_１４のＲ_１４は、芳香族基であることが最も好ましい。また、一般式（１）において、Ｒ_１、Ｒ_２、Ｒ_３、Ｒ_４、Ｒ_５及びＲ_６は、同一の基であることが好ましい。
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本発明において、脂肪族基は、アルキル基、アルケニル基、アルキニル基、置換アルキル基、置換アルケニル基及び置換アルキニル基を意味する。アルキル基は、環状（シクロアルキル基）であってもよい。また、アルキル基は、分岐を有していてもよい。アルキル基の炭素原子数は、１〜３０であることが好ましく、１〜２０であることがさらに好ましく、１〜１０であることが最も好ましい。アルキル基の例には、メチル、エチル、ｉ−プロピル、ブチル、ｉ−ブチル、ｓ−ブチル、ｔ−ブチル、ｔ−ペンチル、ヘキシル、オクチル、ｔ−オクチル、ドデシル及びテトラコシルが含まれる。アルケニル基は、環状（シクロアルケニル基）であってもよい。また、アルケニル基は、分岐を有していてもよい。アルケニル基は、二つ以上の二重結合を有していてもよい。
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アルケニル基の炭素原子数は、２〜３０であることが好ましく、２〜２０であることがさらに好ましく、２〜１０であることが最も好ましい。アルケニル基の例には、ビニル、アリル及び３−ヘプテニルが含まれる。アルキニル基は、環状（シクロアルキニル基）であってもよい。また、アルキニル基は、分岐を有していてもよい。アルキニル基は、二つ以上の三重結合を有していてもよい。アルキニル基の炭素原子数は、２〜３０であることが好ましく、２〜２０であることがさらに好ましく、２〜１０であることが最も好ましい。アルキニル基の例には、エチニル、２−プロピニル、１−ペンチニル及び２，４−オクタジイニルが含まれる。
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置換アルキル基、置換アルケニル基及び置換アルキニル基の置換基の例としては、ハロゲン原子、ニトロ、スルホ、芳香族基、複素環基、−Ｏ−Ｒ_４１、−Ｓ−Ｒ_４２、−ＣＯ−Ｒ_４３、−Ｏ−ＣＯ−Ｒ_４４、−ＣＯ−Ｏ−Ｒ_４５、−Ｏ−ＣＯ−Ｏ−Ｒ_４６、−ＮＲ_４７Ｒ_４８、−ＣＯ−ＮＲ_４９Ｒ_５０、−ＮＲ_５１−ＣＯ−Ｒ_５２、−Ｏ−ＣＯ−ＮＲ_５３Ｒ_５４、−ＳｉＲ_５５Ｒ_５６Ｒ_５７Ｒ_５８及び−Ｏ−ＳｉＲ_５９Ｒ_６０Ｒ_６１Ｒ_６２が含まれる。Ｒ_４１、Ｒ_４２、Ｒ_４３、Ｒ_４４、Ｒ_４５、Ｒ_４６、Ｒ_４７、Ｒ_４８、Ｒ_４９、Ｒ_５０、Ｒ_５１、Ｒ_５２、Ｒ_５３、Ｒ_５４、Ｒ_５５、Ｒ_５６、Ｒ_５７、Ｒ_５８、Ｒ_５９、Ｒ_６０、Ｒ_６１及びＲ_６２は、それぞれ独立に、水素原子、脂肪族基、芳香族基または複素環基である。
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置換アルキル基のアルキル部分は、上記アルキル基と同様である。置換アルキル基の例には、ベンジル、フェネチル、２−メトキシエチル、エトキシメチル、２−（２−メトキシエトキシ）エチル、２−ヒドロキシエチル、ヒドロキシメチル、２−カルボキシエチル、カルボキシメチル、エトキシカルボニルメチル、４−アクリロイルオキシブチル、トリクロロメチル及びパーフルオロペンチルが含まれる。置換アルケニル基のアルケニル部分は、上記アルケニル基と同様である。置換アルケニル基の例には、スチリル及び４−メトキシスチリルが含まれる。置換アルキニル基のアルキニル部分は、上記アルキニル基と同様である。置換アルキニル基の例には、４−ブトキシフェニルエチニル、４−プロピルフェニルエチニル及びトリメチルシリルエチニルが含まれる。
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本発明において、芳香族基は、アリール基及び置換アリール基を意味する。アリール基の炭素原子数は、６〜３０であることが好ましく、６〜２０であることがさらに好ましく、６〜１０であることが最も好ましい。アリール基の例には、フェニル、１−ナフチル及び２−ナフチルが含まれる。置換アリール基の置換基の例には、ハロゲン原子、ニトロ基、スルホン酸基、脂肪族基、芳香族基、複素環基、−Ｏ−Ｒ_７１、−Ｓ−Ｒ_７２、−ＣＯ−Ｒ_７３、−Ｏ−ＣＯ−Ｒ_７４、−ＣＯ−Ｏ−Ｒ_７５、−Ｏ−ＣＯ−Ｏ−Ｒ_７６、−ＮＲ_７７Ｒ_７８、−ＣＯ−ＮＲ_７９Ｒ_８０、−ＮＲ_８１−ＣＯ−Ｒ_８２、−Ｏ−ＣＯ−ＮＲ_８３Ｒ_８４、−ＳｉＲ_８５Ｒ_８６Ｒ_８７Ｒ_８８及び−Ｏ−ＳｉＲ_８９Ｒ_９０Ｒ_９１Ｒ_９２が含まれる。
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Ｒ_７１、Ｒ_７２、Ｒ_７３、Ｒ_７４、Ｒ_７５、Ｒ_７６、Ｒ_７７、Ｒ_７８、Ｒ_７９、Ｒ_８０、Ｒ_８１、Ｒ_８２、Ｒ_８３、Ｒ_８４、Ｒ_８５、Ｒ_８６、Ｒ_８７、Ｒ_８８、Ｒ_８９、Ｒ_９０、Ｒ_９１及びＲ_９２は、それぞれ独立に、水素原子、脂肪族基、芳香族基または複素環基である。
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置換アリール基のアリール部分は、上記アリール基と同様である。置換アリール基の例には、ｐ−ビフェニリル、４−フェニルエチニルフェニル、２−メトキシフェニル、３−メトキシフェニル、４−メトキシフェニル、２−エトキシフェニル、３−エトキシフェニル、４−エトキシフェニル、２−プロポキシフェニル、３−プロポキシフェニル、４−プロポキシフェニル、２−ブトキシフェニル、３−ブトキシフェニル、４−ブトキシフェニル、２−ヘキシルオキシフェニル、３−ヘキシルオキシフェニル、４−ヘキシルオキシフェニル、２−オクチルオキシフェニル、３−オクチルオキシフェニル、４−オクチルオキシフェニル、２−ドデシルオキシフェニル、３−ドデシルオキシフェニル、４−ドデシルオキシフェニル、２−テトラコシルオキシフェニル、３−テトラコシルオキシフェニル、４−テトラコシルオキシフェニル、３，４−ジメトキシフェニル、３，４−ジエトキシフェニル、３，４−ジヘキシルオキシフェニル、２，４−ジメトキシフェニル、２，４−ジエトキシフェニル、２，４−ジヘキシルオキシフェニル、３，５−ジメトキシフェニル、３，５−ジメトキシフェニル、３，５−ジヘキシルオキシフェニル、３，４，５−トリメトキシフェニル、３，４，５−トリエトキシフェニル、３，４，５−トリヘキシルオキシフェニル、２，４，６−トリメトキシフェニル、２，４，６−トリエトキシフェニル、２，４，６−トリヘキシルオキシフェニル、２−フルオロフェニル、３−フルオロフェニル、４−フルオロフェニル、２−クロロフェニル、３−クロロフェニル、４−クロロフェニル、２−ブロモフェニル、３−ブロモフェニル、４−ブロモフェニル、３，４−ジフルオロフェニル、３，４−ジクロロフェニル、３，４−ジブロモフェニル、２，４−ジフルオロフェニル、２，４−ジクロロフェニル、２，４−ジブロモフェニル、３，５−ジフルオロフェニル、３，５−ジクロロフェニル、３，５−ジブロモフェニル、３，４，５−トリフルオロフェニル、３，４，５−トリクロロフェニル、３，４，５−トリブロモフェニル、２，４，６−トリフルオロフェニル、２，４，６−トリクロロフェニル、２，４，６−トリブロモフェニル、ペンタフルオロフェニル、ペンタクロロフェニル、ペンタブロモフェニル、２−ヨードフェニル、３−ヨードフェニル、４−ヨードフェニル、２−ホルミルフェニル、３−ホルミルフェニル、４−ホルミルフェニル、２−ベンゾイルフェニル、３−ベンゾイルフェニル、４−ベンゾイルフェニル、２−カルボキシフェニル、３−カルボキシフェニル、４−カルボキシフェニル、ｏ−トリル、ｍ−トリル、ｐ−トリル、２−エチルフェニル、３−エチルフェニル、４−エチルフェニル、２−（２−メトキシエトキシ）フェニル、３−（２−メトキシエトキシ）フェニル、４−（２−メトキシエトキシ）フェニル、２−エトキシカルボニルフェニル、３−エトキシカルボニルフェニル、４−エトキシカルボニルフェニル、２−ベンゾイルオキシフェニル、３−ベンゾイルオキシフェニル及び４−ベンゾイルオキシフェニルが含まれる。
【００９４】
本発明において、複素環基は置換基を有していてもよい。複素環基の複素環は、５員環または６員環であることが好ましい。複素環基の複素環に脂肪族環、芳香族環または他の複素環が縮合していてもよい。複素環のヘテロ原子の例には、Ｂ、Ｎ、Ｏ、Ｓ、Ｓｅ及びＴｅが含まれる。複素環基の例には、ピロリジン環、モルホリン環、２−ボラ−１，３−ジオキソラン環及び１，３−チアゾリジン環が含まれる。不飽和複素環の例には、イミダゾール環、チアゾール環、ベンゾチアゾール環、ベンゾオキサゾール環、ベンゾトリアゾール環、ベンゾセレナゾール環、ピリジン環、ピリミジン環及びキノリン環が含まれる。複素環基の置換基の例は、置換アリール基の置換基の例と同じである。
【００９５】
トリフェニレン環を有する化合物の分子量は、３００〜２０００であることが好ましい。化合物の沸点は、２６０℃以上であることが好ましい。沸点は、市販の測定装置（例えば、ＴＧ／ＤＴＡ１００、セイコー電子工業社製）を用いて測定出来る。上記一般式（１）のＲ_１〜Ｒ_６の置換基が６個が同一のトリフェニレン環を有する化合物の下記一般式（２）に対応するＲの具体例を以下に示す。
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【化１４】

【００９７】
Ｒとしては、（Ｂ−１）フルオロ、（Ｂ−２）クロロ、（Ｂ−３）ブロモ、（Ｂ−４）ホルミル、（Ｂ−５）ベンゾイル、（Ｂ−６）カルボキシル、（Ｂ−７）ブチルアミノ、（Ｂ−８）ジベンジルアミノ、（Ｂ−９）トリメチルシリルオキシ、（Ｂ−１０）１−ペンチニル、（Ｂ−１１）エトキシカルボニル、（Ｂ−１２）２−ヒドロキシエトキシカルボニル、（Ｂ−１３）フェノキシカルボニル、（Ｂ−１４）Ｎ−フェニルカルバモイル、（Ｂ−１５）Ｎ，Ｎ−ジエチルカルバモイル、（Ｂ−１６）４−メトキシベンゾイルオキシ、（Ｂ−１７）Ｎ−フェニルカルバモイルオキシ、（Ｂ−１８）ヘキシルオキシ、（Ｂ−１９）４−ヘキシルオキシベンゾイルオキシ、（Ｂ−２０）エトキシ、（Ｂ−２１）ベンゾイルオキシ、（Ｂ−２２）ｍ−ドデシルオキシフェニルチオ、（Ｂ−２３）ｔ−オクチルチオ、（Ｂ−２４）ｐ−フルオロベンゾイルチオ、（Ｂ−２５）イソブチリルチオ、（Ｂ−２６）ｐ−メチルベンゼンスルフィニル、（Ｂ−２７）エタンスルフィニル、（Ｂ−２８）ベンゼンスルホニル、（Ｂ−２９）メタンスルホニル、（Ｂ−３０）２−メトキシエトキシ、（Ｂ−３１）プロポキシ、（Ｂ−３２）２−ヒドロキシエトキシ、（Ｂ−３３）２−カルボキシエトキシ、（Ｂ−３４）３−ヘプテニルオキシ、（Ｂ−３５）２−フェニルエトキシ、（Ｂ−３６）トリクロロメトキシ（Ｂ−３７）２−プロピニルオキシ、（Ｂ−３８）２，４−オクタジイニルオキシ、（Ｂ−３９）パーフルオロペンチルオキシ、（Ｂ−４０）エトキシカルボニルメトキシ、（Ｂ−４１）ｐ−メトキシフェノキシ、（Ｂ−４２）ｍ−エトキシフェノキシ、（Ｂ−４３）ｏ−クロロフェノキシ、（Ｂ−４４）ｍ−ドデシルオキシフェノキシ、（Ｂ−４５）４−ピリジルオキシ、（Ｂ−４６）ペンタフルオロベンゾイルオキシ、（Ｂ−４７）ｐ−ヘキシルオキシベンゾイルオキシ、（Ｂ−４８）１−ナフトイルオキシ、（Ｂ−４９）２−ナフトイルオキシ、（Ｂ−５０）５−イミダゾールカルボニルオキシ、（Ｂ−５１）ｏ−フェノキシカルボニルベンゾイルオキシ、（Ｂ−５２）ｍ−（２−メトキシエトキシ）ベンゾイルオキシ、（Ｂ−５３）ｏ−カルボキシベンゾイルオキシ、（Ｂ−５４）ｐ−ホルミルベンゾイルオキシ、（Ｂ−５５）ｍ−エトキシカルボニルベンゾイルオキシ、（Ｂ−５６）ｐ−ピバロイルベンゾイルオキシ、（Ｂ−５７）プロピオニルオキシ、（Ｂ−５８）フェニルアセトキシ、（Ｂ−５９）シンナモイルオキシ、（Ｂ−６０）ヒドロキシアセトキシ、（Ｂ−６１）エトキシカルボニルアセトキシ、（Ｂ−６２）ｍ−ブトキシフェニルプロピオロイルオキシ、（Ｂ−６３）プロピオロイルオキシ、（Ｂ−６４）トリメチルシリルプロピオロイルオキシ、（Ｂ−６５）４−オクテノイルオキシ、（Ｂ−６６）３−ヒドロキシプロピオニルオキシ、（Ｂ−６７）２−メトキシエトキシアセトキシ、（Ｂ−６８）パーフルオロブチリルオキシ、（Ｂ−６９）メタンスルホニルオキシ、（Ｂ−７０）ｐ−トルエンスルホニルオキシ、（Ｂ−７１）トリエチルシリル、（Ｂ−７２）ｍ−ブトキシフェノキシカルボニルアミノ、（Ｂ−７３）ヘキシル、（Ｂ−７４）フェニル、（Ｂ−７５）４−ピリジル、（Ｂ−７６）ベンジルオキシカルボニルオキシ、（Ｂ−７７）ｍ−クロロベンズアミド、（Ｂ−７８）４−メチルアニリノ等を挙げることが出来る。
【００９８】
上記一般式（１）のＲ_１〜Ｒ_６の置換基が５個が水素で６個が同一のＲのトリフェニレン環を有する化合物の下記一般式（３）に対応するＲの具体例を以下に示す。
【００９９】
【化１５】

【０１００】
Ｒとしては、（Ｂ−７９）ニトロ、（Ｂ−８０）スルホ、（Ｂ−８１）ホルミル、（Ｂ−８２）カルボキシル、（Ｂ−８３）メトキシカルボニル、（Ｂ−８４）ベンジルオキシカルボニル、（Ｂ−８５）フェノキシカルボニルを挙げることが出来る。
【０１０１】
上記一般式（１）のＲ_１が水酸基で、Ｒ_２〜Ｒ_６の置換基５個が同一のＲのトリフェニレン環を有する化合物の下記一般式（４）に対応するＲの具体例を以下に示す。
【０１０２】
【化１６】

【０１０３】
Ｒとしては、（Ｂ−８６）ブトキシ、（Ｂ−８７）ヘキシルオキシ、（Ｂ−８８）ドデシルオキシ、（Ｂ−８９）ヘキサノイルオキシ、（Ｂ−９０）カルボキシメトキシを挙げることが出来る。
【０１０４】
更に上記一般式（１）のＲ_１〜Ｒ_５の別の例として、下記Ｂ−９１〜Ｂ１００を挙げることが出来る。
【０１０５】
【化１７】

【０１０６】
【化１８】

【０１０７】
芳香族環を少なくとも二つ有し、且つ少なくとも二つの芳香族環が平面構造を有する化合物を有する化合物のドープ中への添加量は、少なすぎると効果が十分出ない場合があり、多すぎるとブリードアウトする場合があるので、セルロースエステルのドープ中に０．４〜１０質量％配合することが好ましく、更に１．５〜１０質量％の範囲が好ましい。また、セルロースエステルフィルム中に含有させる量としては、セルロースエスエル１００質量部に対して０．０１〜２０質量％が好ましく、更に５〜２０質量％が好ましく、特に８〜２０質量％が好ましい。
【０１０８】
次に本発明に係わる棒状液晶性化合物としては、アゾメチン類、アゾキシ類、シアノビフェニル類、シアノフェニルエステル類、安息香酸エステル類、シクロヘキサンカルボン酸フェニルエステル類、シアノフェニルシクロヘキサン類、シアノ置換フェニルピリミジン類、アルコキシ置換フェニルピリミジン類、フェニルジオキサン類、トラン類およびアルケニルシクロヘキシルベンゾニトリル類が好ましく用いられる。なお、棒状液晶性化合物には、金属錯体も含まれる。また、棒状液晶性化合物を繰り返し単位中に含む液晶ポリマーも、棒状液晶性化合物として用いることができる。言い換えると、棒状液晶性化合物は、（液晶）ポリマーと結合していてもよい。棒状液晶性化合物については、季刊化学総説第２２巻液晶の化学（１９９４）日本化学会編の第４章、第７章および第１１章、および液晶デバイスハンドブック日本学術振興会第１４２委員会編の第３章に記載がある。棒状液晶性化合物の複屈折率は、０．００１〜０．７の範囲にあることが好ましい。棒状液晶性化合物は、その配向状態を固定するために、重合性基を有することが好ましい。重合性基（Ｑ）の例を、以下に示す。
【０１０９】
【化１９】

【０１１０】
重合性基（Ｑ）としては、不飽和重合性基（Ｑ１〜Ｑ７）、エポキシ基（Ｑ８）またはアジリジニル基（Ｑ９）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（Ｑ１〜Ｑ６）であることが最も好ましい。棒状液晶性化合物は、短軸方向に対してほぼ対称となる分子構造を有することが好ましい。そのためには、棒状分子構造の両端に重合性基を有することが好ましい。以下に、棒状液晶性化合物の例を示す。
【０１１１】
【化２０】

【０１１２】
【化２１】

【０１１３】
【化２２】

【０１１４】
【化２３】

【０１１５】
【化２４】

【０１１６】
【化２５】

【０１１７】
本発明に係わる液晶表示装置に使用するセルロースエステルフィルムが、劣化するのを防ぐための酸化防止剤やラジカル捕捉剤等の劣化防止剤をセルロースエステルフィルム中に含有させることが好ましい。
【０１１８】
上記劣化防止剤としては、ヒンダードフェノール系の化合物が好ましく用いられ、２，６−ジ−ｔ−ブチル−ｐ−クレゾール、ペンタエリスリチル−テトラキス〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート〕、トリエチレングリコール−ビス〔３−（３−ｔ−ブチル−５−メチル−４−ヒドロキシフェニル）プロピオネート〕、１，６−ヘキサンジオール−ビス〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート〕、２，４−ビス−（ｎ−オクチルチオ）−６−（４−ヒドロキシ−３，５−ジ−ｔ−ブチルアニリノ）−１，３，５−トリアジン、２，２−チオ−ジエチレンビス〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート〕、オクタデシル−３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート、Ｎ，Ｎ′−ヘキサメチレンビス（３，５−ジ−ｔ−ブチル−４−ヒドロキシ−ヒドロシンナマミド）、１，３，５−トリメチル−２，４，６−トリス（３，５−ジ−ｔ−ブチル−４−ヒドロキシベンジル）ベンゼン、トリス−（３，５−ジ−ｔ−ブチル−４−ヒドロキシベンジル）−イソシアヌレイト等が挙げられる。特に２，６−ジ−ｔ−ブチル−ｐ−クレゾール、ペンタエリスリチル−テトラキス〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート〕、トリエチレングリコール−ビス〔３−（３−ｔ−ブチル−５−メチル−４−ヒドロキシフェニル）プロピオネート〕が好ましい。また例えば、Ｎ，Ｎ′−ビス〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオニル〕ヒドラジン等のヒドラジン系の金属不活性剤やトリス（２，４−ジ−ｔ−ブチルフェニル）フォスファイト等のリン系加工安定剤を併用してもよい。これらの化合物の添加量は、セルロースエステルに対して質量割合で１．０ｐｐｍ〜１．０％が好ましく、１０〜１０００ｐｐｍが更に好ましい。
【０１１９】
また、本発明に係わるセルロースエステルフィルムが紫外線により劣化するのを防ぐために、上記劣化防止剤の他に、液晶表示装置に注ぐ紫外線をカットまたは弱める紫外線吸収剤を含有させることが好ましい。紫外線吸収剤としては、波長３７０ｎｍ以下の紫外線の吸収能に優れており、かつ、液晶表示性の観点から、波長４００ｎｍ以上の可視光の吸収が少ないものが好ましい。例えばオキシベンゾフェノン系化合物、ベンゾトリアゾール系化合物、サリチル酸エステル系化合物、ベンゾフェノン系化合物、シアノアクリレート系化合物、ニッケル錯塩系化合物等を挙げることが出来る。特に好ましい紫外線吸収剤は、ベンゾトリアゾール系化合物やベンゾフェノン系化合物である。中でも、ベンゾトリアゾール系化合物は、セルロースエステルに対する不要な着色が少ないことから好ましい。例えばチバ・スペシャルティ・ケミカルズ社製のチヌビン１０９、チヌビン１７１、チヌビン３２６、チヌビン３２７、チヌビン３２８等を好ましく用いることが出来るが、低分子の紫外線吸収剤は使用量によっては可塑剤同様に製膜中にウェブに析出したり、揮発する虞があるので、その添加量はセルロースエステルに対して０．０１〜５質量％、好ましくは０．１３〜３質量％である。なお、これらの紫外線吸収剤は本発明に有用な芳香族環を少なくとも二つ有し、且つ少なくとも二つの芳香族環が平面構造を有する化合物と重複するものもある。
【０１２０】
本発明において、セルロースエステルフィルム中に微粒子を含有しているのが好ましく、微粒子としては、例えば二酸化ケイ素、二酸化チタン、酸化アルミニウム、酸化ジルコニウム、炭酸カルシウム、カオリン、タルク、焼成ケイ酸カルシウム、水和ケイ酸カルシウム、ケイ酸アルミニウム、ケイ酸マグネシウム、リン酸カルシウム等の無機微粒子や架橋高分子微粒子を含有させることが好ましい。中でも二酸化ケイ素がフィルムのヘイズを小さく出来るので好ましい。微粒子の２次粒子の平均粒径は０．０１〜１．０μｍの範囲で、その含有量はセルロースエステルに対して０．００５〜０．３質量％が好ましい。二酸化ケイ素のような微粒子には有機物により表面処理されている場合が多いが、このようなものはフィルムのヘイズを低下出来るため好ましい。表面処理で好ましい有機物としては、ハロシラン類、アルコキシシラン類（特にメチル基を有するアルコキシシラン類）、シラザン、シロキサンなどがあげられる。微粒子の平均粒径が大きい方がマット効果は大きく、反対に平均粒径の小さい方は透明性に優れるため、好ましい微粒子の一次粒子の平均粒径は５〜５０ｎｍで、より好ましくは７〜１６ｎｍである。これらの微粒子はセルロースエステルフィルム中では、通常、凝集体として存在しセルロースエステルフィルム表面に０．０１〜１．０μｍの凹凸を生成させることが好ましい。二酸化ケイ素の微粒子としてはアエロジル社製のＡＥＲＯＳＩＬ（アエロジル）２００、２００Ｖ、３００、Ｒ９７２、Ｒ９７２Ｖ、Ｒ９７４、Ｒ２０２、Ｒ８１２、ＯＸ５０、ＴＴ６００等を挙げることが出来、好ましくはＡＥＲＯＳＩＬ（アエロジル）２００Ｖ、Ｒ９７２、Ｒ９７２Ｖ、Ｒ９７４、Ｒ２０２、Ｒ８１２である。これらの微粒子は２種以上併用してもよい。２種以上併用する場合、任意の割合で混合して使用することが出来る。この場合、平均粒径や材質の異なる微粒子、例えばＡＥＲＯＳＩＬ（アエロジル）２００ＶとＲ９７２Ｖを質量比で０．１：９９．９〜９９．９〜０．１の範囲で使用出来る。本発明において、微粒子はドープ調製時、セルロースエステル、他の添加剤及び有機溶媒とともに含有させて分散してもよいが、セルロースエステル溶液とは、別に微粒子分散液のような十分に分散させた状態でドープを調製するのが好ましい。微粒子を分散させるために、前もって有機溶媒にひたしてから高剪断力を有する分散機（高圧分散装置）で細分散させておくのが好ましい。その後により多量の有機溶媒に分散して、セルロースエステル溶液と合流させ、インラインミキサーで混合してドープとすることが好ましい。この場合、微粒子分散液に紫外線吸収剤を加え紫外線吸収剤液としてもよい。
【０１２１】
上記の劣化防止剤、紫外線吸収剤及び／または微粒子は、セルロースエステル溶液の調製の際に、セルロースエステルや溶媒と共に添加してもよいし、溶液調製中や調製後に添加してもよい。
【０１２２】
光学異方性層は、棒状液晶性化合物あるいは後述の重合性開始剤や任意の添加剤（例、可塑剤、モノマー、界面活性剤、セルロースエステル、１，３，５−トリアジン化合物、カイラル剤）を含む液晶組成物（塗布液）を、配向膜の上に塗布することで形成することが出来る。
【０１２３】
一方、円盤状（ディスコティック）液晶性化合物を用いる例としては、Ｃ．Ｄｅｓｔｒａｄｅらの研究報告、Ｍｏｌ．Ｃｒｙｓｔ．７１巻、１１１頁（１９８１年）に記載されているベンゼン誘導体、Ｃ．Ｄｅｓｔｒａｄｅらの研究報告、Ｍｏｌ．Ｃｒｙｓｔ．１２２巻、１４１頁（１９８５年）、Ｐｈｙｓｉｃｓ ｌｅｔｔ，Ａ，７８巻、８２頁（１９９０）に記載されているトルキセン誘導体、Ｂ．Ｋｏｈｎｅらの研究報告、Ａｎｇｅｗ．Ｃｈｅｍ．９６巻、７０頁（１９８４年）に記載されたシクロヘキサン誘導体及びＪ．Ｍ．Ｌｅｈｎらの研究報告、Ｊ．Ｃｈｅｍ．Ｃｏｍｍｕｎ．，１７９４頁（１９８５年）、Ｊ．Ｚｈａｎｇらの研究報告、Ｊ．Ａｍ．Ｃｈｅｍ．Ｓｏｃ．１１６巻、２６５５頁（１９９４年）に記載されているアザクラウン系やフェニルアセチレン系マクロサイクルなどを挙げることができる。さらに、円盤状液晶性化合物としては、一般的にこれらを分子中心の母核とし、直鎖のアルキル基やアルコキシ基、置換ベンゾイルオキシ基等がその直鎖として放射線状に置換された構造のものも含まれ、液晶性を示す。ただし、分子自身が負の一軸性を有し、一定の配向を付与できるものであればこれらに限定されるものではない。また、本発明において、円盤状液晶性化合物から形成される光学異方性層は、最終的にできた物が前記化合物である必要はなく、例えば、低分子の円盤状液晶性化合物が熱、光等で反応する基を有しており、結果的に熱、光等で反応により重合または架橋し、高分子量化し液晶性を失ったものも含まれる。円盤状液晶性化合物の好ましい例は、特開平８−５０２０６号公報に記載されている。また、円盤状液晶性化合物の重合については、特開平８−２７２８４公報に記載がある。
【０１２４】
円盤状液晶性化合物を重合により固定するためには、円盤状液晶性化合物の円盤状コアに、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、重合性基を有する円盤状液晶性化合物は、下記一般式（５）で表される化合物であることが好ましい。
【０１２５】
一般式（５） Ｄ（−Ｌ−Ｐ）_ｎ
式中、Ｄは円盤状コアであり；Ｌは二価の連結基であり、Ｐは重合性基であり、そして、ｎは４〜１２の整数である。円盤状コア（Ｄ）の例を以下に示す。以下の各例において、ＬＰ（またはＰＬ）は、二価の連結基（Ｌ）と重合性基（Ｐ）との組み合わせを意味する。
【０１２６】
【化２６】

【０１２７】
【化２７】

【０１２８】
【化２８】

【０１２９】
一般式（５）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二価の連結基であることがさらに好ましい。二価の連結基（Ｌ）は、アルキレン基、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二価の連結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、１〜１２であることが好ましい。アルケニレン基の炭素原子数は、２〜１２であることが好ましい。アリーレン基の炭素原子数は、６〜１０であることが好ましい。
【０１３０】
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（Ｐ）に結合する。ＡＬはアルキレン基またはアルケニレン基、ＡＲはアリーレン基を意味する。なお、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）を有していてもよい。
【０１３１】
Ｌ１：−ＡＬ−ＣＯ−Ｏ−ＡＬ−
Ｌ２：−ＡＬ−ＣＯ−Ｏ−ＡＬ−Ｏ−
Ｌ３：−ＡＬ−ＣＯ−Ｏ−ＡＬ−Ｏ−ＡＬ−
Ｌ４：−ＡＬ−ＣＯ−Ｏ−ＡＬ−Ｏ−ＣＯ−
Ｌ５：−ＣＯ−ＡＲ−Ｏ−ＡＬ−
Ｌ６：−ＣＯ−ＡＲ−Ｏ−ＡＬ−Ｏ−
Ｌ７：−ＣＯ−ＡＲ−Ｏ−ＡＬ−Ｏ−ＣＯ−
Ｌ８：−ＣＯ−ＮＨ−ＡＬ−
Ｌ９：−ＮＨ−ＡＬ−Ｏ−
Ｌ１０：−ＮＨ−ＡＬ−Ｏ−ＣＯ−
Ｌ１１：−Ｏ−ＡＬ−
Ｌ１２：−Ｏ−ＡＬ−Ｏ−
Ｌ１３：−Ｏ−ＡＬ−Ｏ−ＣＯ−
Ｌ１４：−Ｏ−ＡＬ−Ｏ−ＣＯ−ＮＨ−ＡＬ−
Ｌ１５：−Ｏ−ＡＬ−Ｓ−ＡＬ−
Ｌ１６：−Ｏ−ＣＯ−ＡＲ−Ｏ−ＡＬ−ＣＯ−
Ｌ１７：−Ｏ−ＣＯ−ＡＲ−Ｏ−ＡＬ−Ｏ−ＣＯ−
Ｌ１８：−Ｏ−ＣＯ−ＡＲ−Ｏ−ＡＬ−Ｏ−ＡＬ−Ｏ−ＣＯ−
Ｌ１９：−Ｏ−ＣＯ−ＡＲ−Ｏ−ＡＬ−Ｏ−ＡＬ−Ｏ−ＡＬ−Ｏ−ＣＯ−
Ｌ２０：−Ｓ−ＡＬ−
Ｌ２１：−Ｓ−ＡＬ−Ｏ−
Ｌ２２：−Ｓ−ＡＬ−Ｏ−ＣＯ−
Ｌ２３：−Ｓ−ＡＬ−Ｓ−ＡＬ−
Ｌ２４：−Ｓ−ＡＲ−ＡＬ−
一般式（５）の重合性基（Ｐ）は、重合反応の種類に応じて決定する。重合性基（Ｐ）の例を以下に示す。
【０１３２】
【化２９】

【０１３３】
重合性基（Ｐ）は、不飽和重合性基（Ｐ１、Ｐ２、Ｐ３、Ｐ７、Ｐ８、Ｐ１５、Ｐ１６、Ｐ１７）またはエポキシ基（Ｐ６、Ｐ１８）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（Ｐ１、Ｐ７、Ｐ８、Ｐ１５、Ｐ１６、Ｐ１７）であることが最も好ましい。一般式（５）において、ｎは４〜１２の整数である。具体的な数字は、円盤状コア（Ｄ）の種類に応じて決定される。なお、複数のＬとＰ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。
【０１３４】
円盤状液晶性化合物を用いる場合、光学異方性層は負の複屈折を有する層であって、そして円盤状構造単位の面が、セルロースアセテートフィルム表面に対して傾き、且つ円盤状構造単位の面とセルロースアセテートフィルム表面とのなす角度が、光学異方性層の深さ方向に変化していることが好ましい。
【０１３５】
円盤状構造単位の面の角度（傾斜角）は、一般に、光学異方性層の深さ方向でかつ光学異方性層の底面からの距離の増加と共に増加または減少している。傾斜角は、距離の増加と共に増加することが好ましい。さらに、傾斜角の変化としては、連続的増加、連続的減少、間欠的増加、間欠的減少、連続的増加と連続的減少を含む変化、及び増加及び減少を含む間欠的変化などを挙げることができる。間欠的変化は、厚さ方向の途中で傾斜角が変化しない領域を含んでいる。傾斜角は、傾斜角が変化しない領域を含んでいても、全体として増加または減少していることが好ましい。さらに、傾斜角は全体として増加していることが好ましく、特に連続的に変化することが好ましい。
【０１３６】
支持体側の円盤状単位の傾斜角は、一般に円盤状液晶性化合物あるいは配向膜の材料を選択することにより、またはラビング処理方法の選択をすることにより、調整することができる。また、表面側（空気側）の円盤状単位の傾斜角は、一般に円盤状液晶性化合物あるいは円盤状液晶性化合物とともに使用する他の化合物を選択することにより調整することができる。円盤状液晶性化合物とともに使用する化合物の例としては、可塑剤、界面活性剤、重合性モノマー及びポリマーなどを挙げることができる。更に、傾斜角の変化の程度も、上記と同様の選択により調整できる。
【０１３７】
円盤状液晶性化合物とともに使用する可塑剤、界面活性剤及び重合性モノマーとしては、円盤状液晶性化合物と相溶性を有し、円盤状液晶性化合物の傾斜角の変化を与えられるか、あるいは配向を阻害しない限り、どのような化合物も使用することができる。これらの中で、重合性モノマー（例、ビニル基、ビニルオキシ基、アクリロイル基及びメタクリロイル基を有する化合物）が好ましい。上記化合物の添加量は、円盤状液晶性化合物に対して一般に１〜５０質量％の範囲にあり、５〜３０質量％の範囲にあることが好ましい。
【０１３８】
円盤状液晶性化合物とともに使用するポリマーとしては、円盤状液晶性化合物と相溶性を有し、円盤状液晶性化合物に傾斜角の変化を与えられる限り、どのようなポリマーでも使用することができる。ポリマーの例としては、セルロースエステルを挙げることができる。セルロースエステルの好ましい例としては、セルロースアセテート、セルロースアセテートプロピオネート、ヒドロキシプロピルセルロース及びセルロースアセテートブチレートを挙げることができる。円盤状液晶性化合物の配向を阻害しないように、上記ポリマーの添加量は、円盤状液晶性化合物に対して一般に０．１〜１０質量％の範囲にあり、０．１〜８質量％の範囲にあることがより好ましく、０．１〜５質量％の範囲にあることがさらに好ましい。
【０１３９】
光学異方性層は、一般に円盤状液晶性化合物および他の化合物を溶剤に溶解した溶液を配向膜上に塗布し、乾燥し、次いでディスコティックネマチック相形成温度まで加熱し、その後配向状態（ディスコティックネマチック相）を維持して冷却することにより得られる。あるいは、上記光学異方性層は、円盤状液晶性化合物及び他の化合物（更に、例えば重合性モノマー、光重合開始剤）を溶剤に溶解した溶液を配向膜上に塗布し、乾燥し、次いでディスコティックネマチック相形成温度まで加熱したのち重合させ（ＵＶ光の照射等により）、さらに冷却することにより得られる。本発明に用いる円盤状液晶性化合物のディスコティックネマチック液晶相−固相転移温度としては、７０〜３００℃が好ましく、特に７０〜１７０℃が好ましい。
【０１４０】
本発明に係わるドープを形成するのに有用な有機溶媒は、セルロースエステル、芳香族環を少なくとも二つ有し、且つ少なくとも二つの芳香族環が平面構造を有する化合物、その他の添加剤を同時に溶解するものであれば制限なく用いることが出来る。例えば、塩素系有機溶媒としては、塩化メチレン、非塩素系有機溶媒としては、酢酸メチル、酢酸エチル、酢酸アミル、アセトン、テトラヒドロフラン、１，３−ジオキソラン、１，４−ジオキサン、シクロヘキサノン、ギ酸エチル、２，２，２−トリフルオロエタノール、２，２，３，３−ヘキサフルオロ−１−プロパノール、１，３−ジフルオロ−２−プロパノール、１，１，１，３，３，３−ヘキサフルオロ−２−メチル−２−プロパノール、１，１，１，３，３，３−ヘキサフルオロ−２−プロパノール、２，２，３，３，３−ペンタフルオロ−１−プロパノール、ニトロエタン等を挙げることが出来、塩化メチレン、酢酸メチル、酢酸エチル、アセトンを好ましく使用し得る。特に酢酸メチルが好ましい。
【０１４１】
本発明に係わるドープには、上記有機溶媒の他に、１〜４０質量％の炭素原子数１〜４のアルコールを含有させることが好ましい。ドープ中のアルコールの比率が高くなるとウェブがゲル化し、金属支持体からの剥離が容易になり、また、アルコールの割合が少ない時は非塩素系有機溶媒系でのセルロースエステルの溶解を促進する役割もある。炭素原子数１〜４のアルコールとしては、メタノール、エタノール、ｎ−プロパノール、ｉｓｏ−プロパノール、ｎ−ブタノール、ｓｅｃ−ブタノール、ｔｅｒｔ−ブタノールを挙げることが出来る。これらのうちドープの安定性、沸点も比較的低く、乾燥性も良く、且つ毒性がないこと等からエタノールが好ましい。
【０１４２】
ドープ中のセルロースエステルの濃度は１５〜４０質量％、ドープ粘度は１００〜５００ポアズ（Ｐ）の範囲に調整されることが良好なフィルム面品質を得る上で好ましい。
【０１４３】
本発明に係わるドープには可塑剤を添加することが出来る。可塑剤としては、リン酸エステル系可塑剤、フタル酸エステル系可塑剤、グリコレート系可塑剤、クエン酸エステル系可塑剤などを好ましく用いることが出来る。リン酸エステル系可塑剤として、前記のトリフェニルホスフェート（ＴＰＰ）、トリクレジルホスフェート、クレジルジフェニルホスフェート、オクチルジフェニルホスフェート、ジフェニルビフェニルホスフェート、トリオクチルホスフェート、トリブチルホスフェート等、フタル酸エステル系可塑剤として、ジエチルフタレート、ジメトキシエチルフタレート、ジメチルフタレート、ジオクチルフタレート、ジブチルフタレート、ジ−２−エチルヘキシルフタレート、ブチルベンジルフタレート、ジベンジルフタレート、クエン酸エステルとして、クエン酸アセチルトリエチル、クエン酸アセチルトリブチル、グリコレート系可塑剤として、アルキルフタリルアルキルグリコレート、またその他、オレイン酸ブチル、リシノール酸メチルアセチル、セバチン酸ジブチル、トリアセチン等も挙げることが出来る。本発明においては、グリコレート系可塑剤を好ましく用いることが出来、アルキルフタリルアルキルグリコレートのアルキルは炭素原子数１〜８のアルキル基のものを挙げることが出来る。好ましいグリコレート系可塑剤としては、メチルフタリルメチルグリコレート、エチルフタリルエチルグリコレート（ＥＰＥＧ）、プロピルフタリルプロピルグリコレート、ブチルフタリルブチルグリコレート、オクチルフタリルオクチルグリコレート、メチルフタリルエチルグリコレート、エチルフタリルメチルグリコレート、エチルフタリルプロピルグリコレート、プロピルフタリルエチルグリコレート、メチルフタリルプロピルグリコレート、メチルフタリルブチルグリコレート、エチルフタリルブチルグリコレート、ブチルフタリルメチルグリコレート、ブチルフタリルエチルグリコレート、プロピルフタリルブチルグリコレート、ブチルフタリルプロピルグリコレート、メチルフタリルオクチルグリコレート、エチルフタリルオクチルグリコレート、オクチルフタリルメチルグリコレート、オクチルフタリルエチルグリコレート等を挙げることが出来、メチルフタリルメチルグリコレート、エチルフタリルエチルグリコレート、プロピルフタリルプロピルグリコレート、ブチルフタリルブチルグリコレート、オクチルフタリルオクチルグリコレートが好ましく、特にエチルフタリルエチルグリコレートが好ましく用いられる。またこれらアルキルフタリルアルキルグリコレートを２種以上混合して使用してもよい。
【０１４４】
アルキルフタリルアルキルグリコレートの添加量は密着力低減及びフィルムからのブリードアウト抑制などの観点から、セルロースエステルに対して１〜１０質量％が好ましい。本発明においては、アルキルフタリルアルキルグリコレートと共に上記の他の可塑剤を混合してもよい。
【０１４５】
【実施例】
以下、実施例により本発明を説明するが、本発明はこれらに限定されない。
【０１４６】
まず、各種物性の測定方法について、以下にまとめて記載する。
（セルロースエステルフィルム置換度、および酢化度の測定）
アセチルの置換度（ＤＳａ）およびプロピオニルの置換度（ＤＳｐ）の測定は、ＡＳＴＭ−Ｄ８１７−９６に準じて測定した。酢酸の置換度（ＤＳａ）とは、セルロースエステル分子中、すべてのＯＨ基の個数がいくつの酢酸と反応して置換されたか、それをグルコピラノーズ単位で表したものであり、従って、ＤＳａは０から３の値をとる。
【０１４７】
また、酢化度は、セルロースアセテート中の酢酸の質量％であり、下記の式に従って算出される。
【０１４８】
酢化度＝｛ＤＳａ×（ＣＨ_３ＣＯＯＨの分子量）｝／｛（Ｃ_６Ｈ_１０Ｏ_５）の分子量＋ＤＳａ×（ＣＨ_２ＣＯの分子量）＋ＤＳｐ×（ＣＨ_３ＣＨＣＯの分子量）｝
（Ｒｏ、Ｒｔ、遅相軸方向）
アッベの屈折率計により試料の平均屈折率を求めた。さらに、自動複屈折計ＫＯＢＲＡ−２１ＡＤＨ（王子計測機器社製）を用いて、２３℃、５５％ＲＨの環境下で、波長が５９０ｎｍにおいて、複屈折率を測定し、得られた位相差の測定値と平均屈折率から計算により屈折率ｎｘ、ｎｙ、ｎｚを求めた。また、同時に遅相軸の方向も測定を行った。
【０１４９】
（動的粘弾性の測定方法）
ＪＩＳ Ｋ７２４４−４に準じて求めた。即ち、フィルムを５×２３ｍｍサイズに長手、幅手方向にそれぞれ切り出し、Ｒｈｅｏｍｅｔｒｉｃ社製 ＳＯＬＩＤ ＡＮＡＬＹＺＥＲ ＲＳＡ ＩＩにより周波数１５．９Ｈｚ、測定温度５０〜２００℃の範囲で測定を行った。
【０１５０】
（リワーク性）
得られた偏光板を１００×１００ｍｍサイズに打ち抜き、ガラス基盤に貼合した。４角の１カ所から偏光板をガラス基盤から少し剥離し、剥離した偏光板を掴みガラス基盤を押さえながら対角方向に剥離していく。同様の操作を計１０枚のサンプルで実施し、以下の基準に従い評価を行った。
【０１５１】
◎：１０枚とも完全に剥離できた
○：１枚のみ部分的に剥離残りが生じた
△：２〜５枚で剥離のこりが生じた
×：６枚以上剥離のこりが生じた
（視野角特性）
視野角特性の評価にはＥＬＤＩＭ社製ＥＺ−ｃｏｎｔｒａｓｔを用い黒表示および白表示時の透過光量を測定した。視野角の評価はコントラスト＝（白表示時の透過光量）／（黒表示時の透過光量）を算出し１０以上を示すパネル面に対する法線方向からの傾き角が左右６０°以上のものを「○」とし、実用上問題ないとの評価を行った。
【０１５２】
実施例１
（ドープの調製）
１質量部のアエロジルＲ９７２と９質量部のエタノールを容器内で混合し、３０ＭＰａの剪断力を有するマントンゴーリン分散機で細分散して微粒子原液とし、耐圧密閉容器に９質量部の塩化メチレンで希釈しフィラー分散希釈液とした。
【０１５３】
１４．２質量部の塩化メチレンに１．２質量部の紫外線吸収剤と０．７質量部のセルロースエステル（表１のＡに記載）を溶解し、３．０質量部の上記フィラー分散希釈液を添加、撹拌してフィラー添加液とした。
【０１５４】
別の耐圧密閉容器に下記のセルロースエステル溶液組成物を導入し、高温溶解方法でセルロースエステル溶液を調製した。耐圧密閉容器内圧力を０．２ＭＰａとし、撹拌しながら溶解させ、更に質量比にして０．０４の上記フィラー添加液を質量比として１のセルロースエステル溶液に注ぎ、十分撹拌してから一晩そのまま放置した。その後溶液を安積濾紙社製の安積濾紙ＮＯ．２４４を使用して濾過し、ドープを調製した。
【０１５５】
【表１】

【０１５６】
Ｘ：アセチル基の置換基の置換度
Ｙ：プロピオニル基および／またはブチリル基の置換度
（セルロースエステル溶液組成物）
セルロースエステルＡ（表１に記載） １００質量部
ＴＰＰ ８．５質量部
ＥＰＥＧ ２質量部
塩化メチレン ３００質量部
エタノール ５７質量部
（光学補償セルロースエステルフィルムの作製）
前記ドープを用いて、ドープ温度３５℃、支持体温度３５℃に調整して、ダイからステンレス製支持体ベルト上に流延した。支持体上での乾燥風温度は４０℃とした。その後支持体温度を２０℃として、残留溶媒量８０質量％でウェブを支持体から剥離した。次いで、テンターを用いてウェブの両端をクリップで把持しながら延伸倍率および延伸時ウェブ温度、延伸時ウェブ残溶を変化させロール状光学補償セルロースエステルフィルムを得た。
【０１５７】
（視野角補償偏光板の作製）
光学補償セルロースエステルフィルムをそれぞれ、６０℃の２ｍｏｌ／Ｌ（リットル）濃度の水酸化ナトリウム水溶液中に２分間浸漬し水洗した後、１００℃で１０分間乾燥して得たアルカリ鹸化処理偏光板用保護フィルムを作製した。
【０１５８】
一方別に、厚さ１２０μｍのポリビニルアルコールフィルムを沃素１質量部、ホウ酸４質量部を含む水溶液１００質量部に浸漬し、５０℃で４倍に延伸して偏光子（偏光膜）を作製した。
【０１５９】
上記偏光子の両面に前記光学補償フィルムをそれぞれ完全鹸化型ポリビニルアルコール５％水溶液を接着剤として用いて各々貼り合わせ偏光板を作製した。なお、この時偏光子の透過軸と光学補償セルロースエステルフィルムの遅相軸は平行になるように貼合を行った。
【０１６０】
上記の方法で作製した視野角補償偏光板用の光学補償フィルム１〜６の膜厚（μｍ）、Ｒｏ（ｎｍ）、Ｒｔ（ｎｍ）、ｔａｎδ（ｍｄ）、ｔａｎδ（ｔｄ）とその比の値とリワーク性および視野角特性の評価結果を下記表２にまとめて記載する。
【０１６１】
【表２】

【０１６２】
上記のように、本発明のフィルムは薄膜化に貢献し、かつリワーク性および視野角特性を両立できた。
【０１６３】
実施例２
上記で作製した視野角補償偏光板の一方の面にアルキル変性ポリビニルアルコール（０．１μｍ）を塗設し、６５℃の温風で乾燥させた後、フィルム長手方向（偏光子の吸収軸方向）と平行にラビング処理を行い配向層を形成した。
【０１６４】
さらに、下記組成の溶液ＬＣ−１を配向層上に塗設し、酸素濃度０．１％以下の条件下で４５０ｍＪ／ｃｍ^３の紫外線により配向固定を行い片側にネマティックハイブリッド構造をもつ光学異方性層を塗設し視野角補償偏光板を得た。なお、上記の処理は、ロールを搬送することにより行った。
【０１６５】
上記実施例１と同様に評価を行ったところ、本発明の光学補償フィルムは実施例１と同様にリワーク性がよく、かつ視野角改善効果はより大きかった。但し、評価は光学異方性層がセル側に来るように貼り合わせて行った。
【０１６６】
（ＬＣ−１溶液）
ＭＥＫ（メチルエチルケトン） ８８質量部
化合物１ ３質量部
化合物２ ３質量部
化合物３ ３質量部
化合物４ ２質量部
イルガキュアー３６９（チバスペシャリティケミカル社製） １質量部
【０１６７】
【化３０】

【０１６８】
実施例３
実施例１において使用したセルロースエステル（表１のＡに記載）を、酢化度６０％のセルロースエステル（表１のＢに記載）に代替し、さらに、下記化合物（レターデーション上昇剤）をセルロースエステル１００質量部に対して４質量部加えた以外は同様にしてロール状光学補償フィルムを得た。
【０１６９】
【化３１】

【０１７０】
上記実施例１と同様に視野角補償偏光板用の光学補償フィルム１１〜１６を作製し評価を行った。評価方法、表示方法等は表２に準ずる。
【０１７１】
【表３】

【０１７２】
上記のように、本発明のフィルムは薄膜化に貢献し、かつリワーク性および視野角特性を両立できた。
【０１７３】
実施例４
実施例３で得られたロール状セルロースエステルフィルムに実施例２と同様にラビング処理および配向層を形成した。
【０１７４】
（円盤状液晶性化合物による光学異方性層の形成）
配向膜上に、下記の円盤状液晶性化合物４１．０１ｇ、エチレンオキサイド変成トリメチロールプロパントリアクリレート（Ｖ＃３６０、大阪有機化学社製）４．０６ｇ、セルロースアセテートブチレート（ＣＡＢ５５１−０．２、イーストマンケミカル社製）０．９０ｇ、セルロースアセテートブチレート（ＣＡＢ５３１−１、イーストマンケミカル社製）０．２３ｇ、光重合開始剤（イルガキュアー９０７、チバガイギー社製）１．３５ｇ、増感剤（カヤキュアーＤＥＴＸ、日本化薬社製）０．４５ｇを、１０２ｇのメチルエチルケトンに溶解した塗布液を、＃３．６のワイヤーバーで塗布した。これを１３０℃の恒温ゾーンで２分間加熱し、円盤状液晶性化合物を配向させた。次に、６０℃の雰囲気下で１２０Ｗ／ｃｍ高圧水銀灯を用いて、１分間ＵＶ照射し円盤状液晶性化合物を重合させた。その後、室温まで放冷した。
【０１７５】
【化３２】

【０１７６】
実施例２と同様に評価を行ったところ、本発明の光学補償フィルムは薄膜化およびリワーク性さらに視野角改善効果を同様に達成できた。
【０１７７】
【発明の効果】
本発明により、第１に、優れた視野角補償機能を有する光学補償フィルムを提供することが出来る。第２には液晶表示装置の薄膜化を達成し、更には生産上の歩留まり、リワーク性を向上させた視野角補償フィルム、前記フィルムを用いた偏光板、前記フィルムを有する液晶表示装置を提供することが出来る。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical compensation film, a viewing angle compensation polarizing plate, and a liquid crystal display.
[0002]
[Prior art]
At present, cellulose ester films (typically, cellulose triacetate films) are preferably used for silver halide photographic materials and optical films because of their transparency and properties free from optical defects. Particularly, it is preferably used for a protective film for a polarizing plate, a protective film for a retardation film, a film for optical compensation or a retardation film of a liquid crystal display.
[0003]
In general, a liquid crystal display device has a viewing angle characteristic in which display quality is degraded when observed from an oblique direction. To improve this, a viewing angle compensation film having an appropriate phase difference function is provided by using a liquid crystal cell and a polarizer. It is known that a method of arranging between them is effective.
[0004]
However, the viewing angle compensation film hinders the thinning of liquid crystal display devices, and thinning is also an important issue for portable liquid crystal display devices. Achieving is an important task.
[0005]
For example, a currently used cellulose triacetate film for a viewing angle compensating polarizing plate protective film has a film thickness of about 80 μm. Reusability at the time of failure of the combination, so-called reworkability, is deteriorated. The deterioration of the reworkability due to thinning becomes noticeable when the thickness is reduced from around 70 μm, becomes remarkable from around 60 μm, and becomes particularly remarkable when the film thickness becomes thinner than 40 μm.
[0006]
As an example of improving the mechanical strength of cellulose acetate, there is JP-A-2000-154201 disclosed as Patent Document 1 below. JP-A-2000-154201 attempts to improve mechanical strength by keeping the average degree of acetylation, the degree of polymerization, and tan δ within a predetermined range, but does not mention the viewing angle improving effect at all. No mention is made of anisotropy in the plane of tan δ.
[0007]
Further, as an example of imparting high functionality and thinning, an example is disclosed in JP-A-2002-156527 shown as Patent Document 2 below. However, in the present invention, no method for improving the reworkability associated with thinning is disclosed, and improvement has been desired from the viewpoint of improving production yield.
[0008]
[Patent Document 1]
JP 2000-154201 A
[0009]
[Patent Document 2]
JP-A-2002-156527
[0010]
[Problems to be solved by the invention]
A first object of the present invention is to provide an optical compensatory film having an excellent viewing angle compensating function. A second object of the present invention is to reduce the thickness of a liquid crystal display device, and to further improve production yield and reworkability. It is an object of the present invention to provide a viewing angle compensating film in which the above is improved, a polarizing plate using the film, and a liquid crystal display having the film.
[0011]
[Means for Solving the Problems]
As a result of intensive studies by the inventors, the object of the present invention has been achieved by adopting any one of the following constitutions [1] to [9].
[0012]
[1] A cellulose ester film having a film thickness of 10 to 70 μm, wherein tan δ (md) and tan δ (td) are respectively defined as tan δ (md) and tan δ (td) in the longitudinal and width directions of the cellulose ester film. tanδ (td) is in the range of 0.1 to 2.0, and satisfies the relationship of tanδ (md)> tanδ (td), and Ro defined by the following formula (I) is 20 to 70 nm. An optical compensation film having an Rt within a range and defined by the following formula (II) of 70 to 400 nm.
[0013]
(I) Ro = (nx−ny) × d
(II) Rt = {(nx + ny) / 2−nz} × d
(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the film thickness direction, and d is the film index. Is the thickness.)
[2] The optical compensation according to [1], wherein the tan δ (md) and the tan δ (td) satisfy a relationship of 0.5 <tan δ (td) / tan δ (md) <1.0. the film.
[0014]
[3] An optical compensation film, further comprising an optically anisotropic layer provided on the surface of the optical compensation film according to [1] or [2].
[0015]
[4] The optical compensation film according to any one of [1] to [3], wherein the cellulose ester film satisfies the following formulas (III) and (IV) at the same time.
[0016]
(III) 2.3 ≦ X + Y ≦ 2.85
(IV) 1.4 ≦ X ≦ 2.85
(However, X is the degree of substitution of the acetyl group, and Y is the degree of substitution of the propionyl group and / or the butyryl group.)
[5] The acetylation degree of the cellulose ester film is in the range of 59.0 to 61.5%, and the compound having at least two aromatic rings is present in an amount of 0.01 to 20 parts by mass based on 100 parts by mass of the cellulose ester. The optical compensation film according to any one of [1] to [3], which comprises:
[0017]
[6] The optical compensation film according to [3], wherein the optically anisotropic layer has a fixed nematic hybrid alignment structure.
[0018]
[7] The optical compensation film according to [3], wherein the optically anisotropic layer is a discotic liquid crystalline compound.
[0019]
[8] In a polarizing plate comprising two protective films and a polarizer, at least one of the protective films is the optical compensation film according to any one of [1] to [7], and the optical compensation film is Wherein the slow axis of the cellulose ester film and the transmission axis of the polarizer are substantially parallel to each other.
[0020]
[9] A liquid crystal display device using the viewing angle compensating polarizing plate according to [8].
[0021]
In the present invention, tan δ represents a loss tangent obtained by measuring dynamic viscoelasticity, and the peak value is the highest tan δ value in a tan δ-temperature (° C.) absorption curve (temperature range of 50 to 200 ° C.).
[0022]
As an actual measuring device, DMS2000 viscoelastic spectrometer manufactured by Seiko, RSA-1 manufactured by Rheometrics, or the like can be used.
[0023]
In the present invention, md represents the casting direction of the cellulose ester film, and td represents the direction perpendicular to the casting direction of the cellulose ester film. Therefore, in the case of a roll-shaped cellulose ester film, md represents the longitudinal direction of the film and td represents the width direction of the film.
[0024]
From the viewpoint of improving the reworkability, the absolute value of the tan δ peak at 50 to 200 ° C is in the range of 0.1 to 2.0, respectively, and tan δ (md)> tan δ (td). Further, it is more preferable to set the range of 0.5 <tanδ (td) / tanδ (md) <1.0.
[0025]
Adjusting the absolute value of the peak of tan δ at 50 to 200 ° C. to 0.1 to 2.0 is also preferable from the viewpoint of improving dimensional stability under wet heat. There is no clear reason for the relationship between the reworkability of the polarizing plate, the peak value of tan δ, and the in-plane anisotropy. However, PVA (polyvinyl alcohol), which is a polarizer, is stretched in the longitudinal direction (md direction) and has a property of being very easily torn in the longitudinal direction. It is thought that the anisotropy of tan δ of the cellulose ester film compensates for the tearability of the polarizing plate, and as a result, the reworkability is improved.
[0026]
Generally, a liquid crystal display device has a viewing angle characteristic, and there is a problem that contrast is reduced when viewed from a position where the angle is changed from the normal direction of the liquid crystal cell. In order to solve this problem, it is known that it is effective to arrange a retardation film (optical compensation film) having an appropriate retardation between the liquid crystal cell and the polarizer. In general, it is necessary that the in-plane retardation (Ro) is in the range of 20 to 70 nm, and the depth direction retardation (Rt) is in the range of 70 to 400 nm.
[0027]
To control the retardation of the cellulose ester film, the degree of substitution of the cellulose ester used and the type of the substituent are important factors. In the present invention, when the degree of acetyl substitution of a cellulose ester is X and the degree of substitution of a propionyl group and / or a butyryl group is Y, 2.3 ≦ X + Y ≦ 2.85 and 1.4 ≦ X ≦ 2.85. By doing so, it was possible to obtain retardation suitable as a viewing angle compensating polarizing plate (integrated viewing angle compensating polarizing plate).
[0028]
In the present invention, the acetylation degree of the cellulose ester film is in the range of 59 to 61.5%, and the compound having at least two aromatic rings is contained in an amount of 0.01 to 20 parts by mass per 100 parts by mass of the cellulose ester film. By including the parts by mass, a retardation suitable as a viewing angle compensating cellulose ester film could be obtained.
[0029]
Furthermore, it is known that it is effective to provide a layer containing a rod-shaped or disc-shaped liquid crystalline compound on an optically-compensated cellulose ester film having a suitable retardation in order to improve the viewing angle characteristics of the liquid crystal display panel. ing. That is, as the optically anisotropic layer, a viewing angle characteristic can be further improved by providing a nematic hybrid structure by aligning rod-like liquid crystal molecules or by providing a disk-like liquid crystal molecule layer.
[0030]
In order to improve the viewing angle characteristics of the liquid crystal display device, the fact that the slow axis of the optically-compensated cellulose ester support and the transmission axis of the polarizer are substantially parallel or orthogonal suppresses light leakage when black display is performed. It is important from the point of view. Further, as described above, the viewing angle characteristics can be improved by coating an optically anisotropic layer with a liquid crystalline compound on the cellulose ester film. In this case, it is very preferable that the slow axis of the cellulose ester film as the support is orthogonal to the slow axis of the optically anisotropic layer.
[0031]
In consideration of industrial mass production of a liquid crystal display device, it is necessary to perform rubbing in a roll state of a cellulose ester film in order to coat an optically anisotropic layer and align a liquid crystal compound. However, rubbing in the width direction is very difficult, and rubbing in the longitudinal direction (the traveling direction) is much easier. On the other hand, in order to make the slow axis of the cellulose ester film perpendicular to this, it is desirable to perform stretching in the width direction. To make a polarizer by stretching, its longitudinal direction is good, so the absorption axis of the polarizer is the longitudinal direction, the transmission axis is the width direction, and eventually the slow axis of the viewing angle compensation cellulose ester film and the transmission axis of the polarizer. Are preferably substantially parallel.
[0032]
It has also been known that the viewing angle can be further improved by introducing a nematic-type high-molecular liquid crystalline compound into a structure that adopts a hybrid orientation in which the pretilt angle of liquid crystal molecules changes in the depth direction as an optically anisotropic layer. ing.
[0033]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
[0034]
First, a method for producing a cellulose ester film by the solution casting method according to the present invention will be described.
[0035]
(1) Dissolution step: This is a step of dissolving the cellulose ester in an organic solvent mainly containing a good solvent for the cellulose ester in a dissolving vessel while stirring to form a dope. There are various dissolution methods, such as dissolving at normal pressure at a temperature lower than the boiling point of the main solvent, performing pressurization at a temperature equal to or higher than the boiling point of the main solvent, performing cooling at a temperature of zero degrees or lower, or performing high pressure. Any of the dissolving methods can be preferably performed, but a high-temperature dissolving method of dissolving in a pressurized state at a boiling point of the main solvent or higher is more preferably used. After dissolution, the dope is filtered with a filter medium, defoamed, and sent to the next step by a pump.
[0036]
In the dope, additives having various functions such as a plasticizer, an antioxidant, an ultraviolet absorber, a matting agent, and a retardation increasing agent can be added. These additives may be added together with the cellulose ester or the solvent during the preparation of the dope, or may be added during or after the preparation of the dope. Further, a heat stabilizer such as a salt of an alkaline earth metal, an antistatic agent, a flame retardant, a slipping agent, an oil agent and the like may be added in some cases.
[0037]
{Circle around (2)} Casting step: The dope is fed to a pressurizing die through a pressurized metering gear pump, and at the casting position, the surface is mirror-finished and an endless metal belt or a rotating metal drum (hereinafter referred to as an infinitely moving belt). (Hereinafter simply referred to as a metal support). In a casting apparatus using a die, a pressure die that can adjust the slit shape of the die portion and easily uniform the film thickness of the web is preferable. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the doping amount may be divided to form a plurality of layers.
[0038]
{Circle around (3)} Solvent evaporation step: a step of heating the web on a metal support to evaporate the organic solvent. In order to evaporate the organic solvent, there are a method in which air is blown from the web side, a method in which heat is transferred from the back side of the metal support by a liquid, a method in which heat is transferred from the front and back sides by radiant heat, and the like. It is preferably used.
[0039]
{Circle around (4)} Peeling step: This is a step of peeling the web from which the organic solvent has evaporated on the metal support from the metal support. The peeled web is sent to the next drying step. If the residual solvent amount (described later) of the web at the time of peeling is too large, peeling is difficult, or conversely, if the web is sufficiently dried on a metal support and then peeled, a part of the web is peeled off in the middle.
[0040]
As a method of increasing the film forming speed, there is gel casting that can peel off even a large amount of the residual solvent. Examples of the method include a method in which a poor solvent for the cellulose ester is added to the dope, gelling is performed after casting the dope, and a method in which the temperature of the metal support is lowered to gelate. When gelling is performed on a metal support, the film strength is high and the film can be peeled off even if the amount of residual solvent is large. As a result, peeling can be accelerated and the film forming speed can be increased. If the residual solvent is peeled off at a higher point, if the web is too soft, the flatness at the time of peeling will be impaired, or shear and vertical streaks will easily occur due to peeling tension. I can decide. In the present invention, it is preferable to peel at 10 to 120% by mass.
[0041]
{Circle around (5)} Drying step: a step of drying the web using a drying device that alternately transports the web through guide rolls arranged in a staggered manner and / or a tenter drying device that transports the web by clipping both ends of the web with clips. is there. In general, hot air is blown to both sides of the web as a drying means, but there is also a method of heating by applying a microwave instead of the wind. Too fast drying tends to impair the flatness of the finished film. The drying temperature throughout is 40-250 ° C, preferably 70-180 ° C. The drying temperature, the amount of drying air, and the drying time vary depending on the organic solvent used, and the drying conditions may be appropriately selected according to the type and combination of the solvents used.
[0042]
In the drying step after peeling from the metal support surface, the web tends to shrink in both directions due to evaporation of the solvent. The quicker it dries at higher temperatures, the greater the shrinkage. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness of the resulting film. From this viewpoint, for example, a method of drying all the steps or a part of the steps as described in Japanese Patent Application Laid-Open No. Sho 62-46625 while holding both ends of the width of the web with clips in the width direction (tenter method) Is preferred. At this time, retardation can be controlled by controlling the stretching ratio of the web, the amount of residual solvent, and the temperature.
[0043]
Furthermore, in the present invention, the film residual solvent amount is 5 to 30%, the temperature during film stretching is 60 to 140 ° C., and the film is stretched in the width direction at a stretch ratio of 1.01 to 2.0 times. As a result, in-plane anisotropy was imparted to tan δ, suitable retardation was imparted, and the reworkability of the polarizing plate was further improved.
[0044]
(6) Winding step: This is a step of winding the dried web as a film. By setting the amount of the residual solvent after drying to be 2% by mass or less, preferably 0.4% by mass or less, a film having good dimensional stability can be obtained. The winding method may be a commonly used winder, and there are methods to control the tension, such as the constant torque method, the constant tension method, the taper tension method, and the program tension control method with constant internal stress. Just do it.
[0045]
The amount of residual solvent can be expressed by the following equation.
Residual solvent amount (% by mass) = {(M−N) / N} × 100
Here, M is the mass of the web at any point in time, and N is the mass of the M when dried at 110 ° C. for 3 hours.
[0046]
The thickness of the cellulose ester film varies depending on the purpose of use, but from the viewpoint of thinning the liquid crystal display device, the finished film preferably has a thickness of 10 to 75 μm, more preferably 10 to 60 μm, and particularly preferably 10 to 40 μm. Is preferred. If it is too thin, for example, the necessary strength as a protective film for a polarizing plate may not be obtained. If the thickness is too large, the superiority of thinning over conventional cellulose ester films is lost. In order to adjust the film thickness, it is preferable to control the dope concentration, the amount of liquid supplied by the pump, the slit gap of the die cap, the extrusion pressure of the die, the speed of the metal support, and the like so as to obtain a desired thickness. Further, as means for making the film thickness uniform, it is preferable that the programmed feedback information is fed back to each of the above-mentioned devices using a film thickness detecting means for adjustment.
[0047]
In the process from immediately after casting through the solution casting film forming method to drying, the atmosphere in the drying apparatus may be air, or may be performed in an inert gas atmosphere such as nitrogen gas or carbon dioxide gas. . However, of course, the danger of the explosion limit of the evaporated solvent in the dry atmosphere must always be considered.
[0048]
Next, the cellulose ester will be described.
The cellulose as a raw material of the cellulose ester used in the present invention is not particularly limited, and examples thereof include cotton linter, wood pulp, and kenaf. Cellulose esters obtained therefrom can be mixed and used at an arbitrary ratio.
[0049]
The number average molecular weight of the cellulose ester used in the present invention is preferably in the range of 60,000 to 300,000, and more preferably in the range of 80,000 to 200,000. Within this range, the mechanical strength of the film is strong and can be used with ease.
[0050]
The number average molecular weight of the cellulose ester is measured by high performance liquid chromatography under the following conditions as follows.
[0051]
Solvent: acetone
Column: MPW x 1 (manufactured by Tosoh Corporation)
Sample concentration: 0.2% by mass / volume
Flow rate: 1.0 ml / min
Sample injection volume: 300 μl
Standard sample: polymethyl methacrylate (Mw = 188,200)
Temperature: 23 ° C.
[0052]
The cellulose ester used in the present invention is obtained by acylating a cellulose raw material. When the acylating agent is an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride), use an organic acid such as acetic acid or an organic solvent such as methylene chloride and use a protic catalyst such as sulfuric acid as a catalyst. To react. The acylating agent is an acid chloride (eg, CH 2₃COCl, C₂H₅COCl, C₃H₇In the case of COCl), the reaction is carried out using a basic compound such as an amine as a catalyst. Specifically, it can be synthesized by the method described in JP-A-10-45804.
[0053]
In the cellulose ester, an acyl group reacts with a hydroxyl group of a cellulose molecule. Cellulose molecules are composed of a number of linked glucose units, and the glucose unit has three hydroxyl groups. The number of acyl groups derived from these three hydroxyl groups is called the degree of substitution.
[0054]
The cellulose ester used in the present invention is a cellulose ester having a propionyl group or a butyryl group in addition to an acetyl group such as cellulose acetate propionate, cellulose acetate butyrate or cellulose acetate propionate butyrate. Note that the butyryl group includes iso- in addition to n-. Cellulose acetate propionate having a high degree of substitution of propionyl groups has excellent water resistance and is useful as a film for a liquid crystal display device.
[0055]
The degree of substitution of the acyl group can be measured according to ASTM-D817-96.
[0056]
In order to prepare a cellulose ester film containing a compound having at least two aromatic rings according to the present invention and at least two aromatic rings having a planar structure, the compound and the cellulose ester film are doped together with an organic solvent. A film is formed by a solution casting film forming method.
[0057]
The compound having at least two aromatic rings according to the present invention and having at least two aromatic rings having a planar structure may be one in which two aromatic rings have a structure close to the same plane. In other words, it has at least 5 or more π electrons of two aromatic rings, π electrons of an aromatic hetero ring, or π electrons of an aromatic ring containing a linking group connecting them, and up to 10 π electrons. Is preferred.
[0058]
The number of aromatic rings contained in this compound is preferably 2 to 20, more preferably 2 to 12, and even more preferably 2 to 8. The aromatic ring includes an aromatic hydrocarbon ring and an aromatic hetero ring. The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring). Aromatic heterocycles are generally unsaturated heterocycles. The aromatic hetero ring is preferably a 5-, 6-, or 7-membered ring, and more preferably a 5- or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable.
[0059]
Examples of the aromatic hetero ring include a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, a pyrazole ring, a furazane ring, a triazole ring, a pyran ring, and a pyridine ring. , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring. As the aromatic ring, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring, a pyrazine ring and a 1,3,5-triazine ring are preferable.
[0060]
At least two aromatic rings have (a) a condensed ring, (b) a direct bond with a single bond, (c) a bond via a linking group, and (d) a π electron. It can be classified into the case where it is bonded through a linking group (a spiro bond cannot be formed due to an aromatic ring). However, in the case of (b) or (c), it is necessary that the two aromatic rings have a planar structure.
[0061]
Examples of the condensed ring of (a) (condensed ring of two or more aromatic rings) include an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a biphenylene ring, a naphthacene ring, Pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline ring, isoquinoline Ring, quinolidine ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring, phenanthridine ring, xanthene ring, phenazine ring, phenothiazine ring, phenoxatiin ring, phenoxazine ring and thiane It includes Ren ring. Preferred are a naphthalene ring, an azulene ring, an indole ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring, a benzotriazole ring and a quinoline ring.
[0062]
The single bond in (b) is preferably a bond between carbon atoms of two aromatic rings. Two aromatic rings may be bonded by two or more single bonds to form an aliphatic ring or a non-aromatic heterocyclic ring between the two aromatic rings.
[0063]
It is also preferable that the linking group (c) or (d) or the linking group having a π electron is bonded to carbon atoms of two aromatic rings. The linking group is preferably an alkylene group, alkenylene group, alkynylene group, -CO-, -O-, -NH-, -S-, or a combination thereof. Examples of the linking group consisting of a combination are shown below. Note that the left and right relationships in the following examples of the linking group may be reversed. For example, -CO-O-, -CO-NH-, -alkylene-O-, -NH-CO-NH-, -NH-CO-O-, -O-CO-O-, -O-alkylene-O -, -CO-alkenylene-, -CO-alkenylene-NH-, -CO-alkenylene-O-, -alkylene-CO-O-alkylene-O-CO-alkylene-, -O-alkylene-CO-O-alkylene -O-CO-alkylene-O-, -O-CO-alkylene-CO-O-, -NH-CO-alkenylene-, -O-CO-alkenylene-, and the like, and particularly an aromatic ring or As the group directly linked to the aromatic hetero ring, -CO- and alkenylene are preferable.
[0064]
The aromatic ring and the linking group may have a substituent. However, the substituent needs to have a sterically hindered structure of two aromatic rings, that is, a planar structure. In the case of steric hindrance, the type and position of the substituent are problematic. As the type of the substituent, a sterically bulky substituent (for example, a tertiary alkyl group) is liable to cause steric hindrance, and the position of the substituent is a position adjacent to the bond of the aromatic ring (the position of the benzene ring). In this case, steric hindrance is likely to occur when substitution is made at the ortho position, so that it is better to avoid it.
[0065]
Examples of the substituent include a halogen atom (F, Cl, Br, I), hydroxyl, carboxyl, cyano, amino, nitro, sulfo, carbamoyl, sulfamoyl, ureido, alkyl, alkenyl, alkynyl, and aliphatic acyl. , Aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group, alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamide group, aliphatic substituted amino group, aliphatic substituted carbamoyl group, aliphatic It includes substituted sulfamoyl groups, aliphatic substituted ureido groups and non-aromatic heterocyclic groups.
[0066]
The alkyl group preferably has 1 to 8 carbon atoms. A chain alkyl group is preferable to a cyclic alkyl group, and a linear alkyl group is particularly preferable. The alkyl group may further have a substituent (eg, hydroxy, carboxy, alkoxy group, alkyl-substituted amino group). Examples of the alkyl group (including the substituted alkyl group) include methyl, ethyl, n-butyl, n-hexyl, 2-hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl, and 2-diethylaminoethyl. The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a linear alkenyl group is particularly preferable. The alkenyl group may further have a substituent. Examples of the alkenyl group include vinyl, allyl and 1-hexenyl. The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a linear alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of the alkynyl group include ethynyl, 1-butynyl and 1-hexynyl.
[0067]
The aliphatic acyl group preferably has 1 to 10 carbon atoms. Examples of the aliphatic acyl group include acetyl, propanoyl and butanoyl. The aliphatic acyloxy group preferably has 1 to 10 carbon atoms. Examples of the aliphatic acyloxy group include acetoxy. The alkoxy group preferably has 1 to 8 carbon atoms. The alkoxy group may further have a substituent (eg, an alkoxy group). Examples of alkoxy groups (including substituted alkoxy groups) include methoxy, ethoxy, butoxy and methoxyethoxy. The alkoxycarbonyl group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonyl group include methoxycarbonyl and ethoxycarbonyl. The alkoxycarbonylamino group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonylamino group include methoxycarbonylamino and ethoxycarbonylamino.
[0068]
The alkylthio group preferably has 1 to 12 carbon atoms. Examples of the alkylthio group include methylthio, ethylthio and octylthio. The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include methanesulfonyl and ethanesulfonyl. The aliphatic amide group preferably has 1 to 10 carbon atoms. Examples of the aliphatic amide group include acetamide. The aliphatic sulfonamide group preferably has 1 to 8 carbon atoms. Examples of the aliphatic sulfonamide group include methanesulfonamide, butanesulfonamide and n-octanesulfonamide. The aliphatic substituted amino group preferably has 1 to 10 carbon atoms. Examples of the aliphatic substituted amino group include dimethylamino, diethylamino and 2-carboxyethylamino. The aliphatic substituted carbamoyl group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted carbamoyl group include methylcarbamoyl and diethylcarbamoyl. The aliphatic substituted sulfamoyl group preferably has 1 to 8 carbon atoms. Examples of the aliphatic substituted sulfamoyl group include methylsulfamoyl and diethylsulfamoyl. The aliphatic substituted ureido group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted ureido group include methyl ureide. Examples of the non-aromatic heterocyclic group include piperidino and morpholino.
[0069]
The molecular weight of these compounds is preferably from 300 to 800. The boiling point is preferably 260 ° C. or higher. The boiling point can be measured using a commercially available measuring device (for example, TG / DTA100, manufactured by Seiko Instruments Inc.). A specific example will be described below.
[0070]
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[0071]
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[0072]
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[0073]
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[0074]
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[0075]
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[0076]
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[0077]
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[0078]
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[0079]
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[0080]
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[0081]
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[0082]
Further, the compound having at least two aromatic rings according to the present invention and having at least two aromatic rings having a planar structure is a compound having a triphenylene ring represented by the following general formula (1) in addition to the above. Are also preferably used.
[0083]
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[0084]
In the general formula (1), R₁, R₂, R₃, R₄, R₅And R₆Is independently a hydrogen atom, a halogen atom, nitro, sulfo, an aliphatic group, an aromatic group, a heterocyclic group, -OR.₁₁, -SR₁₂, -CO-R_Thirteen, -O-CO-R₁₄, -CO-OR_Fifteen, -O-CO-OR₁₆, -NR₁₇R₁₈, -CO-NR₁₉R₂₀, -NR₂₁-CO-R₂₂, -O-CO-NR₂₃R₂₄, -SiR₂₅R₂₆R₂₇, -O-SiR₂₈R₂₉R₃₀, -S-CO-R₃₁, -O-SO₂-R₃₂, -SO-R₃₃, -NR₃₄-CO-OR₃₅, -SO₂-R₃₆Or -NR₃₇-CO-NR₃₈R₃₉And R₁₁, R₁₂, R_Thirteen, R₁₄, R_Fifteen, R₁₆, R₁₇, R₁₈, R₁₉, R₂₀, R₂₁, R₂₂, R₂₃, R₂₄, R₂₅, R₂₆, R₂₇, R₂₈, R₂₉, R₃₀, R₃₁, R₃₂, R₃₃, R₃₄, R₃₅, R₃₆, R₃₇, R₃₈And R₃₉Is each independently a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group;₁And R₂, R₃And R₄Or R₅And R₆May combine with each other to form a ring.
[0085]
R₁, R₂, R₃, R₄, R₅And R₆Is -OR₁₁, -SR₁₂, -O-CO-R₁₄, -O-CO-OR₁₆, -NR₁₇R₁₈, -NR₂₁-CO-R₂₂Or -O-CO-NR₂₃R₂₄Preferably, -OR₁₁, -SR₁₂, -O-CO-R₁₄, -O-CO-OR₁₆Or -O-CO-NR₂₃R₂₄And more preferably -OR.₁₁Or -O-CO-R₁₄More preferably, -O-CO-R₁₄Is most preferred.
[0086]
R₁₁, R₁₂, R_Thirteen, R₁₄, R_Fifteen, R₁₆, R₁₇, R₁₈, R₁₉, R₂₀, R₂₁, R₂₂, R₂₃, R₂₄, R₂₅, R₂₆, R₂₇, R₂₈, R₂₉, R₃₀, R₃₁, R₃₂, R₃₃, R₃₄, R₃₅, R₃₆, R₃₇, R₃₈And R₃₉Is preferably a hydrogen atom, an aliphatic group or an aromatic group. -O-CO-R₁₄R₁₄Is most preferably an aromatic group. In the general formula (1), R₁, R₂, R₃, R₄, R₅And R₆Are preferably the same group.
[0087]
In the present invention, the aliphatic group means an alkyl group, an alkenyl group, an alkynyl group, a substituted alkyl group, a substituted alkenyl group and a substituted alkynyl group. The alkyl group may be cyclic (cycloalkyl group). Further, the alkyl group may have a branch. The alkyl group preferably has 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and most preferably 1 to 10 carbon atoms. Examples of the alkyl group include methyl, ethyl, i-propyl, butyl, i-butyl, s-butyl, t-butyl, t-pentyl, hexyl, octyl, t-octyl, dodecyl and tetracosyl. The alkenyl group may be cyclic (cycloalkenyl group). Further, the alkenyl group may have a branch. An alkenyl group may have two or more double bonds.
[0088]
The alkenyl group preferably has 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, and most preferably 2 to 10 carbon atoms. Examples of the alkenyl group include vinyl, allyl and 3-heptenyl. The alkynyl group may be cyclic (cycloalkynyl group). Further, the alkynyl group may have a branch. An alkynyl group may have two or more triple bonds. The alkynyl group preferably has 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, and most preferably 2 to 10 carbon atoms. Examples of the alkynyl group include ethynyl, 2-propynyl, 1-pentynyl and 2,4-octadiynyl.
[0089]
Examples of the substituent of the substituted alkyl group, the substituted alkenyl group and the substituted alkynyl group include a halogen atom, nitro, sulfo, aromatic group, heterocyclic group, -OR.₄₁, -SR₄₂, -CO-R₄₃, -O-CO-R₄₄, -CO-OR₄₅, -O-CO-OR₄₆, -NR₄₇R₄₈, -CO-NR₄₉R₅₀, -NR₅₁-CO-R₅₂, -O-CO-NR₅₃R₅₄, -SiR₅₅R₅₆R₅₇R₅₈And -O-SiR₅₉R₆₀R₆₁R₆₂Is included. R₄₁, R₄₂, R₄₃, R₄₄, R₄₅, R₄₆, R₄₇, R₄₈, R₄₉, R₅₀, R₅₁, R₅₂, R₅₃, R₅₄, R₅₅, R₅₆, R₅₇, R₅₈, R₅₉, R₆₀, R₆₁And R₆₂Is each independently a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group.
[0090]
The alkyl part of the substituted alkyl group is the same as the above-mentioned alkyl group. Examples of the substituted alkyl group include benzyl, phenethyl, 2-methoxyethyl, ethoxymethyl, 2- (2-methoxyethoxy) ethyl, 2-hydroxyethyl, hydroxymethyl, 2-carboxyethyl, carboxymethyl, ethoxycarbonylmethyl, Includes 4-acryloyloxybutyl, trichloromethyl and perfluoropentyl. The alkenyl part of the substituted alkenyl group is the same as the above alkenyl group. Examples of the substituted alkenyl group include styryl and 4-methoxystyryl. The alkynyl part of the substituted alkynyl group is the same as the above alkynyl group. Examples of substituted alkynyl groups include 4-butoxyphenylethynyl, 4-propylphenylethynyl and trimethylsilylethynyl.
[0091]
In the present invention, the aromatic group means an aryl group and a substituted aryl group. The number of carbon atoms of the aryl group is preferably from 6 to 30, more preferably from 6 to 20, and most preferably from 6 to 10. Examples of the aryl group include phenyl, 1-naphthyl and 2-naphthyl. Examples of the substituent of the substituted aryl group include a halogen atom, a nitro group, a sulfonic group, an aliphatic group, an aromatic group, a heterocyclic group, -OR.₇₁, -SR₇₂, -CO-R₇₃, -O-CO-R₇₄, -CO-OR₇₅, -O-CO-OR₇₆, -NR₇₇R₇₈, -CO-NR₇₉R₈₀, -NR₈₁-CO-R₈₂, -O-CO-NR₈₃R₈₄, -SiR₈₅R₈₆R₈₇R₈₈And -O-SiR₈₉R₉₀R₉₁R₉₂Is included.
[0092]
R₇₁, R₇₂, R₇₃, R₇₄, R₇₅, R₇₆, R₇₇, R₇₈, R₇₉, R₈₀, R₈₁, R₈₂, R₈₃, R₈₄, R₈₅, R₈₆, R₈₇, R₈₈, R₈₉, R₉₀, R₉₁And R₉₂Is each independently a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group.
[0093]
The aryl part of the substituted aryl group is the same as the above-mentioned aryl group. Examples of the substituted aryl group include p-biphenylyl, 4-phenylethynylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 2-ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 2-ethoxyphenyl, Propoxyphenyl, 3-propoxyphenyl, 4-propoxyphenyl, 2-butoxyphenyl, 3-butoxyphenyl, 4-butoxyphenyl, 2-hexyloxyphenyl, 3-hexyloxyphenyl, 4-hexyloxyphenyl, 2-octyloxy Phenyl, 3-octyloxyphenyl, 4-octyloxyphenyl, 2-dodecyloxyphenyl, 3-dodecyloxyphenyl, 4-dodecyloxyphenyl, 2-tetracosyloxyphenyl, 3-tetracosyloxyphenyl, 4- Tet Kosyloxyphenyl, 3,4-dimethoxyphenyl, 3,4-diethoxyphenyl, 3,4-dihexyloxyphenyl, 2,4-dimethoxyphenyl, 2,4-diethoxyphenyl, 2,4-dihexyloxyphenyl , 3,5-dimethoxyphenyl, 3,5-dimethoxyphenyl, 3,5-dihexyloxyphenyl, 3,4,5-trimethoxyphenyl, 3,4,5-triethoxyphenyl, 3,4,5-tri Hexyloxyphenyl, 2,4,6-trimethoxyphenyl, 2,4,6-triethoxyphenyl, 2,4,6-trihexyloxyphenyl, 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2-bromophenyl, 3-bromo Phenyl, 4-bromophenyl, 3,4-difluorophenyl, 3,4-dichlorophenyl, 3,4-dibromophenyl, 2,4-difluorophenyl, 2,4-dichlorophenyl, 2,4-dibromophenyl, 3,5 -Difluorophenyl, 3,5-dichlorophenyl, 3,5-dibromophenyl, 3,4,5-trifluorophenyl, 3,4,5-trichlorophenyl, 3,4,5-tribromophenyl, 2,4 6-trifluorophenyl, 2,4,6-trichlorophenyl, 2,4,6-tribromophenyl, pentafluorophenyl, pentachlorophenyl, pentabromophenyl, 2-iodophenyl, 3-iodophenyl, 4-iodophenyl , 2-formylphenyl, 3-formylphenyl, 4-formylphenyl, 2-ben Zoylphenyl, 3-benzoylphenyl, 4-benzoylphenyl, 2-carboxyphenyl, 3-carboxyphenyl, 4-carboxyphenyl, o-tolyl, m-tolyl, p-tolyl, 2-ethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 2- (2-methoxyethoxy) phenyl, 3- (2-methoxyethoxy) phenyl, 4- (2-methoxyethoxy) phenyl, 2-ethoxycarbonylphenyl, 3-ethoxycarbonylphenyl, 4-ethoxy Includes carbonylphenyl, 2-benzoyloxyphenyl, 3-benzoyloxyphenyl and 4-benzoyloxyphenyl.
[0094]
In the present invention, the heterocyclic group may have a substituent. The heterocyclic ring of the heterocyclic group is preferably a 5- or 6-membered ring. An aliphatic ring, an aromatic ring, or another heterocyclic ring may be condensed to the heterocyclic ring of the heterocyclic group. Examples of heteroatoms in the heterocycle include B, N, O, S, Se and Te. Examples of the heterocyclic group include a pyrrolidine ring, a morpholine ring, a 2-bora-1,3-dioxolane ring, and a 1,3-thiazolidine ring. Examples of the unsaturated heterocyclic ring include an imidazole ring, a thiazole ring, a benzothiazole ring, a benzoxazole ring, a benzotriazole ring, a benzoselenazole ring, a pyridine ring, a pyrimidine ring and a quinoline ring. Examples of the substituent of the heterocyclic group are the same as those of the substituent of the substituted aryl group.
[0095]
The molecular weight of the compound having a triphenylene ring is preferably from 300 to 2,000. The boiling point of the compound is preferably 260 ° C. or higher. The boiling point can be measured using a commercially available measuring device (for example, TG / DTA100, manufactured by Seiko Instruments Inc.). R of the above general formula (1)₁~ R₆Specific examples of R corresponding to the following general formula (2) of a compound having the same triphenylene ring in which six substituents are the same are shown below.
[0096]
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[0097]
R represents (B-1) fluoro, (B-2) chloro, (B-3) bromo, (B-4) formyl, (B-5) benzoyl, (B-6) carboxyl, (B-7) ) Butylamino, (B-8) dibenzylamino, (B-9) trimethylsilyloxy, (B-10) 1-pentynyl, (B-11) ethoxycarbonyl, (B-12) 2-hydroxyethoxycarbonyl, B-13) Phenoxycarbonyl, (B-14) N-phenylcarbamoyl, (B-15) N, N-diethylcarbamoyl, (B-16) 4-methoxybenzoyloxy, (B-17) N-phenylcarbamoyloxy , (B-18) hexyloxy, (B-19) 4-hexyloxybenzoyloxy, (B-20) ethoxy, (B-21) benzoyloxy, (B-22) -Dodecyloxyphenylthio, (B-23) t-octylthio, (B-24) p-fluorobenzoylthio, (B-25) isobutyrylthio, (B-26) p-methylbenzenesulfinyl, (B-27) ethane Sulfinyl, (B-28) benzenesulfonyl, (B-29) methanesulfonyl, (B-30) 2-methoxyethoxy, (B-31) propoxy, (B-32) 2-hydroxyethoxy, (B-33) 2-carboxyethoxy, (B-34) 3-heptenyloxy, (B-35) 2-phenylethoxy, (B-36) trichloromethoxy (B-37) 2-propynyloxy, (B-38) 2,4- Octadiynyloxy, (B-39) perfluoropentyloxy, (B-40) ethoxycarbonylmethoxy, (B-41) -Methoxyphenoxy, (B-42) m-ethoxyphenoxy, (B-43) o-chlorophenoxy, (B-44) m-dodecyloxyphenoxy, (B-45) 4-pyridyloxy, (B-46) Pentafluorobenzoyloxy, (B-47) p-hexyloxybenzoyloxy, (B-48) 1-naphthoyloxy, (B-49) 2-naphthoyloxy, (B-50) 5-imidazolecarbonyloxy, (B-51) o-phenoxycarbonylbenzoyloxy, (B-52) m- (2-methoxyethoxy) benzoyloxy, (B-53) o-carboxybenzoyloxy, (B-54) p-formylbenzoyloxy, (B-55) m-ethoxycarbonylbenzoyloxy, (B-56) p-pivaloylbenzoyloxy, (B-57) propionyloxy, (B-58) phenylacetoxy, (B-59) cinnamoyloxy, (B-60) hydroxyacetoxy, (B-61) ethoxycarbonylacetoxy, (B-62) m-butoxy Phenylpropioloyloxy, (B-63) propioloyloxy, (B-64) trimethylsilylpropioloyloxy, (B-65) 4-octenoyloxy, (B-66) 3-hydroxypropionyloxy, (B -67) 2-methoxyethoxyacetoxy, (B-68) perfluorobutyryloxy, (B-69) methanesulfonyloxy, (B-70) p-toluenesulfonyloxy, (B-71) triethylsilyl, (B -72) m-butoxyphenoxycarbonylamino, (B-73) hexyl, (B-7) ) Phenyl, (B-75) 4-pyridyl, (B-76) benzyloxycarbonyloxy, (B-77) m-chlorobenzamide, it may be mentioned (B-78) 4-methylanilino like.
[0098]
R of the above general formula (1)₁~ R₆Specific examples of R corresponding to the following general formula (3) of a compound having a triphenylene ring having 5 hydrogens and 6 identical Rs are shown below.
[0099]
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[0100]
R represents (B-79) nitro, (B-80) sulfo, (B-81) formyl, (B-82) carboxyl, (B-83) methoxycarbonyl, (B-84) benzyloxycarbonyl, B-85) Phenoxycarbonyl.
[0101]
R of the above general formula (1)₁Is a hydroxyl group and R₂~ R₆Specific examples of R corresponding to the following general formula (4) of a compound having five triphenylene rings having the same R are shown below.
[0102]
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[0103]
Examples of R include (B-86) butoxy, (B-87) hexyloxy, (B-88) dodecyloxy, (B-89) hexanoyloxy, and (B-90) carboxymethoxy.
[0104]
Further, R in the above general formula (1)₁~ R₅As another example, the following B-91 to B100 can be mentioned.
[0105]
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[0106]
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[0107]
The amount of the compound having at least two aromatic rings and having at least two aromatic rings having a planar structure in the dope may be insufficient when the amount is too small, and may not be sufficiently effective. Since it may bleed out, it is preferable to add 0.4 to 10% by mass in the dope of the cellulose ester, more preferably 1.5 to 10% by mass. The amount contained in the cellulose ester film is preferably from 0.01 to 20% by mass, more preferably from 5 to 20% by mass, and particularly preferably from 8 to 20% by mass, based on 100 parts by mass of the cellulose ester.
[0108]
Next, as the rod-like liquid crystalline compound according to the present invention, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines , Alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitrile are preferably used. Note that the rod-like liquid crystal compound also includes a metal complex. Further, a liquid crystal polymer containing a rod-shaped liquid crystal compound in a repeating unit can also be used as the rod-shaped liquid crystal compound. In other words, the rod-like liquid crystalline compound may be bonded to a (liquid crystal) polymer. The rod-like liquid crystal compound is described in Quarterly Review of Chemistry, Vol. 22, Liquid Crystal Chemistry (1994), Chapters 4, 7, and 11 of the Chemical Society of Japan, and the Liquid Crystal Device Handbook, edited by the 142nd Committee of the Japan Society for the Promotion of Science. It is described in Chapter 3. The birefringence of the rod-shaped liquid crystalline compound is preferably in the range of 0.001 to 0.7. The rod-shaped liquid crystalline compound preferably has a polymerizable group in order to fix the alignment state. Examples of the polymerizable group (Q) are shown below.
[0109]
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[0110]
The polymerizable group (Q) is preferably an unsaturated polymerizable group (Q1 to Q7), an epoxy group (Q8) or an aziridinyl group (Q9), more preferably an unsaturated polymerizable group, and ethylene. Most preferably, it is an unsaturated polymerizable group (Q1 to Q6). The rod-like liquid crystalline compound preferably has a molecular structure that is substantially symmetric with respect to the minor axis direction. For that purpose, it is preferable to have a polymerizable group at both ends of the rod-shaped molecular structure. Hereinafter, examples of the rod-shaped liquid crystalline compound will be described.
[0111]
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[0112]
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[0113]
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[0114]
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[0115]
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[0116]
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[0117]
It is preferable that the cellulose ester film used in the liquid crystal display device according to the present invention contains a deterioration inhibitor such as an antioxidant or a radical scavenger for preventing the cellulose ester film from being deteriorated.
[0118]
As the above-mentioned deterioration inhibitor, hindered phenol compounds are preferably used, and 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl) are used. -4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3 5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,3 5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- ( , 5-Di-tert-butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3,5 -Trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate And the like. Particularly, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, a hydrazine-based metal deactivator such as N, N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine or tris (2,4-di-t- A phosphorus-based processing stabilizer such as (-butylphenyl) phosphite may be used in combination. The amount of these compounds to be added is preferably 1.0 ppm to 1.0%, more preferably 10 to 1000 ppm by mass relative to the cellulose ester.
[0119]
In addition, in order to prevent the cellulose ester film according to the present invention from being deteriorated by ultraviolet rays, it is preferable to contain, in addition to the above-mentioned deterioration inhibitor, an ultraviolet absorber which cuts or weakens ultraviolet rays poured into the liquid crystal display device. As the ultraviolet absorber, those which are excellent in the ability to absorb ultraviolet light having a wavelength of 370 nm or less and have low absorption of visible light having a wavelength of 400 nm or more are preferable from the viewpoint of liquid crystal display properties. Examples thereof include oxybenzophenone-based compounds, benzotriazole-based compounds, salicylic acid ester-based compounds, benzophenone-based compounds, cyanoacrylate-based compounds, and nickel complex-based compounds. Particularly preferred ultraviolet absorbers are benzotriazole-based compounds and benzophenone-based compounds. Above all, a benzotriazole-based compound is preferable because unnecessary coloring of the cellulose ester is small. For example, Tinuvin 109, Tinuvin 171, Tinuvin 326, Tinuvin 327, Tinuvin 328, etc., manufactured by Ciba Specialty Chemicals, can be preferably used. The amount added is 0.01 to 5% by mass, and preferably 0.13 to 3% by mass, based on the cellulose ester, since it may be deposited on the web or volatilized. Some of these ultraviolet absorbers have at least two aromatic rings useful in the present invention, and some of them overlap with compounds having at least two aromatic rings having a planar structure.
[0120]
In the present invention, the cellulose ester film preferably contains fine particles. Examples of the fine particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, and hydrated. It is preferable to include inorganic fine particles such as calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate and crosslinked polymer fine particles. Among them, silicon dioxide is preferable because the haze of the film can be reduced. The average particle size of the secondary particles of the fine particles is in the range of 0.01 to 1.0 μm, and the content thereof is preferably 0.005 to 0.3% by mass based on the cellulose ester. Fine particles such as silicon dioxide are often surface-treated with an organic substance, but such particles are preferable because the haze of the film can be reduced. Preferred organic materials for the surface treatment include halosilanes, alkoxysilanes (especially alkoxysilanes having a methyl group), silazane, siloxane and the like. The larger the average particle size of the fine particles, the greater the matting effect, and the smaller the average particle size, the more excellent the transparency. Therefore, the average primary particle size of the preferred fine particles is 5 to 50 nm, more preferably 7 to 16 nm. It is. These fine particles are usually present as an aggregate in the cellulose ester film, and it is preferable to form irregularities of 0.01 to 1.0 μm on the surface of the cellulose ester film. Examples of the fine particles of silicon dioxide include AEROSIL (Aerosil) 200, 200V, 300, R972, R972V, R974, R202, R812, OX50, TT600, etc., and preferably AEROSIL (Aerosil) 200V, R972. R972V, R974, R202, and R812. Two or more of these fine particles may be used in combination. When two or more kinds are used in combination, they can be used in a mixture at an arbitrary ratio. In this case, fine particles having different average particle sizes and different materials, for example, AEROSIL (Aerosil) 200V and R972V can be used in a mass ratio of 0.1: 99.9 to 99.9 to 0.1. In the present invention, the fine particles may be contained and dispersed together with the cellulose ester, other additives and an organic solvent during the preparation of the dope, but in a state in which the fine particles are dispersed sufficiently as a fine particle dispersion separately from the cellulose ester solution. It is preferred to prepare a dope with In order to disperse the fine particles, it is preferable that the fine particles are dipped in an organic solvent in advance and then finely dispersed by a disperser having a high shearing force (high-pressure dispersing device). Thereafter, it is preferable that the dope is dispersed in a larger amount of an organic solvent, combined with the cellulose ester solution, and mixed with an in-line mixer to form a dope. In this case, an ultraviolet absorber may be added to the fine particle dispersion to form an ultraviolet absorber liquid.
[0121]
The above-mentioned deterioration inhibitor, ultraviolet absorber and / or fine particles may be added together with the cellulose ester or the solvent during the preparation of the cellulose ester solution, or may be added during or after the preparation of the solution.
[0122]
The optically anisotropic layer is composed of a rod-like liquid crystalline compound or a polymerizable initiator described below and optional additives (eg, a plasticizer, a monomer, a surfactant, a cellulose ester, a 1,3,5-triazine compound, a chiral agent). Can be formed by applying a liquid crystal composition (coating solution) containing
[0123]
On the other hand, examples of using a discotic (discotic) liquid crystalline compound include C.I. Destrade et al., Mol. Cryst. 71, p. 111 (1981); Destrade et al., Mol. Cryst. 122, p. 141 (1985), Physics lett, A, vol. 78, p. 82 (1990); Research report by Kohne et al., Angew. Chem. Vol. 96, p. 70 (1984); M. Lehn et al., J. Am. Chem. Commun. , P. 1794 (1985); Research report by Zhang et al. Am. Chem. Soc. 116, p. 2655 (1994), and azacrown-based and phenylacetylene-based macrocycles. Further, discotic liquid crystalline compounds generally have a structure in which these are used as a core of a molecular center, and linear alkyl groups, alkoxy groups, substituted benzoyloxy groups, and the like are radially substituted as the linear chains. And shows liquid crystallinity. However, the molecule is not limited to these as long as the molecule itself has negative uniaxiality and can impart a certain orientation. Further, in the present invention, the optically anisotropic layer formed from the discotic liquid crystalline compound does not need to be a compound finally formed, for example, a low-molecular discotic liquid crystalline compound is heat, It also has a group that has a group that reacts with light or the like, and consequently polymerizes or crosslinks by reaction with heat, light, or the like, has a high molecular weight, and loses liquid crystallinity. Preferred examples of the discotic liquid crystalline compound are described in JP-A-8-50206. The polymerization of a discotic liquid crystalline compound is described in JP-A-8-27284.
[0124]
In order to fix the discotic liquid crystalline compound by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline compound. However, when a polymerizable group is directly connected to the disc-shaped core, it becomes difficult to maintain the alignment state in the polymerization reaction. Therefore, a linking group is introduced between the discotic core and the polymerizable group. Therefore, the discotic liquid crystalline compound having a polymerizable group is preferably a compound represented by the following general formula (5).
[0125]
General formula (5) D (-LP)_n
Wherein D is a discotic core; L is a divalent linking group, P is a polymerizable group, and n is an integer from 4-12. Examples of the disc-shaped core (D) are shown below. In each of the following examples, LP (or PL) means a combination of a divalent linking group (L) and a polymerizable group (P).
[0126]
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[0127]
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[0128]
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[0129]
In the general formula (5), 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 a combination thereof. Preferably, the divalent linking group is a divalent linking group. The divalent linking group (L) is a divalent group obtained by combining at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO-, -NH-, -O- and -S-. More preferably, it is a linking group. The divalent linking group (L) is most preferably a divalent linking group obtained by combining at least two divalent groups selected from the group consisting of an alkylene 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 arylene group preferably has 6 to 10 carbon atoms.
[0130]
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 (P). AL represents an alkylene group or an alkenylene group, and AR represents an arylene group. Note that the alkylene group, alkenylene group, and arylene group may have a substituent (eg, an alkyl group).
[0131]
L1: -AL-CO-O-AL-
L2: -AL-CO-O-AL-O-
L3: -AL-CO-O-AL-O-AL-
L4: -AL-CO-O-AL-O-CO-
L5: -CO-AR-O-AL-
L6: -CO-AR-O-AL-O-
L7: -CO-AR-O-AL-O-CO-
L8: -CO-NH-AL-
L9: -NH-AL-O-
L10: -NH-AL-O-CO-
L11: -O-AL-
L12: -O-AL-O-
L13: -O-AL-O-CO-
L14: -O-AL-O-CO-NH-AL-
L15: -O-AL-S-AL-
L16: -O-CO-AR-O-AL-CO-
L17: -O-CO-AR-O-AL-O-CO-
L18: -O-CO-AR-O-AL-O-AL-O-CO-
L19: -O-CO-AR-O-AL-O-AL-O-AL-O-CO-
L20: -S-AL-
L21: -S-AL-O-
L22: -S-AL-O-CO-
L23: -S-AL-S-AL-
L24: -S-AR-AL-
The polymerizable group (P) in the general formula (5) is determined according to the type of the polymerization reaction. Examples of the polymerizable group (P) are shown below.
[0132]
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[0133]
The polymerizable group (P) is preferably an unsaturated polymerizable group (P1, P2, P3, P7, P8, P15, P16, P17) or an epoxy group (P6, P18). More preferably, it is most preferably an ethylenically unsaturated polymerizable group (P1, P7, P8, P15, P16, P17). In the general formula (5), n is an integer of 4 to 12. Specific numbers are determined according to the type of the disc-shaped core (D). The combination of a plurality of L and P may be different, but is preferably the same.
[0134]
When a discotic liquid crystalline compound is used, the optically anisotropic layer is a layer having negative birefringence, and the surface of the discotic structural unit is inclined with respect to the cellulose acetate film surface, and the discotic structural unit is It is preferable that the angle between the surface and the cellulose acetate film surface changes in the depth direction of the optically anisotropic layer.
[0135]
The angle (tilt angle) of the surface of the disc-shaped structural unit generally increases or decreases in the depth direction of the optically anisotropic layer and as the distance from the bottom surface of the optically anisotropic layer increases. Preferably, the tilt angle increases with increasing distance. Further, the change in the inclination angle may include a continuous increase, a continuous decrease, an intermittent increase, an intermittent decrease, a change including the continuous increase and the continuous decrease, and an intermittent change including the increase and the decrease. it can. The intermittent change includes a region where the tilt angle does not change in the thickness direction. It is preferable that the inclination angle increases or decreases as a whole even if it includes a region where the inclination angle does not change. Further, the inclination angle is preferably increased as a whole, and is particularly preferably changed continuously.
[0136]
The tilt angle of the disc-shaped unit on the side of the support can be generally adjusted by selecting a disc-shaped liquid crystalline compound or a material of an alignment film, or by selecting a rubbing treatment method. In addition, the inclination angle of the discotic unit on the surface side (air side) can be generally adjusted by selecting a discotic liquid crystalline compound or another compound used together with the discotic liquid crystalline compound. Examples of the compound used together with the discotic liquid crystalline compound include a plasticizer, a surfactant, a polymerizable monomer, and a polymer. Further, the degree of change of the inclination angle can be adjusted by the same selection as described above.
[0137]
The plasticizer, surfactant and polymerizable monomer used together with the discotic liquid crystalline compound are compatible with the discotic liquid crystalline compound and can change the tilt angle of the discotic liquid crystalline compound, or can be oriented. Any compound can be used as long as it does not inhibit Among these, a polymerizable monomer (eg, a compound having a vinyl group, a vinyloxy group, an acryloyl group, and a methacryloyl group) is preferable. The amount of the compound added is generally in the range of 1 to 50% by mass, and preferably in the range of 5 to 30% by mass, based on the discotic liquid crystalline compound.
[0138]
As the polymer used together with the discotic liquid crystalline compound, any polymer can be used as long as it has compatibility with the discotic liquid crystalline compound and can change the tilt angle of the discotic liquid crystalline compound. Examples of the polymer include a cellulose ester. Preferred examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, hydroxypropylcellulose and cellulose acetate butyrate. In order not to hinder the alignment of the discotic liquid crystalline compound, the amount of the polymer is generally in the range of 0.1 to 10% by mass, and preferably in the range of 0.1 to 8% by mass, based on the discotic liquid crystalline compound. Is more preferable, and even more preferably in the range of 0.1 to 5% by mass.
[0139]
The optically anisotropic layer is generally formed by applying a solution in which a discotic liquid crystalline compound and other compounds are dissolved in a solvent onto an alignment film, drying the solution, and then heating the film to a discotic nematic phase formation temperature. (Nematic phase). Alternatively, the optically anisotropic layer is formed by applying a solution in which a discotic liquid crystal compound and another compound (for example, a polymerizable monomer and a photopolymerization initiator) are dissolved in a solvent onto an alignment film, drying, and then drying. It is obtained by heating to a discotic nematic phase formation temperature, polymerizing (by irradiation with UV light, etc.), and further cooling. The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline compound used in the present invention is preferably from 70 to 300C, particularly preferably from 70 to 170C.
[0140]
Organic solvents useful for forming the dope according to the present invention include a cellulose ester, a compound having at least two aromatic rings, and a compound in which at least two aromatic rings have a planar structure, and other additives. If it does, it can be used without limitation. For example, as a chlorine-based organic solvent, methylene chloride, as a non-chlorine-based organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolan, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- Examples include 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, and the like. As a result, methylene chloride, methyl acetate, ethyl acetate and acetone can be preferably used. Particularly, methyl acetate is preferable.
[0141]
The dope according to the present invention preferably contains 1 to 40% by mass of an alcohol having 1 to 4 carbon atoms in addition to the organic solvent. When the proportion of alcohol in the dope is high, the web gels and the peeling from the metal support becomes easy, and when the proportion of alcohol is small, the role of promoting the dissolution of the cellulose ester in a non-chlorine organic solvent system. There is also. Examples of the alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol and tert-butanol. Among them, ethanol is preferred because of its stability, the boiling point is relatively low, the drying property is good, and there is no toxicity.
[0142]
The concentration of the cellulose ester in the dope is preferably adjusted to 15 to 40% by mass, and the viscosity of the dope is preferably adjusted to 100 to 500 poise (P) in order to obtain good film surface quality.
[0143]
A plasticizer can be added to the dope according to the present invention. As the plasticizer, a phosphate ester plasticizer, a phthalate ester plasticizer, a glycolate plasticizer, a citrate ester plasticizer, and the like can be preferably used. Phosphate ester plasticizers such as the above-mentioned triphenyl phosphate (TPP), tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate and tributyl phosphate; , Diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, butyl benzyl phthalate, dibenzyl phthalate, citrate as acetyl triethyl citrate, acetyl tributyl citrate, glycolate-based Alkyl phthalyl alkyl glycolate as plasticizer, butyl oleate, methyl ricinoleate Cetyl, dibutyl sebacate, triacetin or the like can be mentioned. In the present invention, a glycolate-based plasticizer can be preferably used, and the alkyl of the alkylphthalylalkyl glycolate includes an alkyl group having 1 to 8 carbon atoms. Preferred glycolate plasticizers include methylphthalylmethyl glycolate, ethylphthalylethyl glycolate (EPEG), propylphthalylpropyl glycolate, butylphthalylbutyl glycolate, octylphthalyloctyl glycolate, and methylphthalyl. Ethyl glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, propyl phthalyl ethyl glycolate, methyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl Glycolate, butylphthalylethyl glycolate, propylphthalylbutylglycolate, butylphthalylpropylglycolate, methylphthalyloctyl glycolate, ethylphthalyloctylate Examples include ruglycolate, octylphthalylmethyl glycolate, octylphthalylethyl glycolate, and the like.Methylphthalylmethyl glycolate, ethylphthalylethyl glycolate, propylphthalylpropyl glycolate, butylphthalylbutyl glycolate And octylphthalyloctyl glycolate are preferred, and ethylphthalylethyl glycolate is particularly preferred. Further, two or more of these alkylphthalylalkyl glycolates may be used as a mixture.
[0144]
The amount of the alkylphthalylalkyl glycolate to be added is preferably 1 to 10% by mass based on the cellulose ester from the viewpoints of reducing adhesion and suppressing bleed-out from the film. In the present invention, the above-mentioned other plasticizer may be mixed together with the alkylphthalylalkyl glycolate.
[0145]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.
[0146]
First, methods for measuring various physical properties are summarized and described below.
(Measurement of cellulose ester film substitution degree and acetylation degree)
The substitution degree of acetyl (DSa) and the substitution degree of propionyl (DSp) were measured according to ASTM-D817-96. The degree of substitution of acetic acid (DSa) is the number of all OH groups reacted and replaced in the cellulose ester molecule by the number of acetic acids, which is expressed in glucopyranose units. Takes a value from 0 to 3.
[0147]
The degree of acetylation is the mass% of acetic acid in cellulose acetate and is calculated according to the following equation.
[0148]
Degree of acetylation = ｛DSa × (CH₃COOH molecular weight)｝ / ｛(C₆H₁₀O₅) + DSa × (CH₂CO molecular weight) + DSp × (CH₃CHCO molecular weight)
(Ro, Rt, slow axis direction)
The average refractive index of the sample was determined by Abbe's refractometer. Further, using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments), the birefringence was measured at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH, and the obtained phase difference was measured. The refractive indices nx, ny, and nz were calculated from the values and the average refractive index. At the same time, the direction of the slow axis was also measured.
[0149]
(Measurement method of dynamic viscoelasticity)
It was determined according to JIS K7244-4. That is, the film was cut out in a longitudinal direction and a width direction to a size of 5 × 23 mm, and the measurement was performed by SOLID ANALYZER RSA II manufactured by Rheometrics at a frequency of 15.9 Hz and a measurement temperature of 50 to 200 ° C.
[0150]
(Reworkability)
The obtained polarizing plate was punched out to a size of 100 × 100 mm and bonded to a glass substrate. The polarizing plate is slightly peeled off from the glass substrate from one of the four corners, and the polarizing plate is peeled off diagonally while holding the peeled polarizing plate and holding the glass substrate. The same operation was performed on a total of 10 samples, and evaluation was performed according to the following criteria.
[0151]
：: All 10 sheets were completely peeled off
○: Partial peeling remains only on one sheet
Δ: Peeling residue occurred on 2 to 5 sheets
×: Peeling residue occurred on 6 or more sheets.
(Viewing angle characteristics)
For evaluating the viewing angle characteristics, the amount of transmitted light during black display and white display was measured using EZ-contrast manufactured by ELDIM. The evaluation of the viewing angle was performed by calculating the contrast = (the amount of transmitted light during white display) / (the amount of transmitted light during black display). ○ ”was evaluated as having no practical problem.
[0152]
Example 1
(Preparation of dope)
1 part by weight of Aerosil R972 and 9 parts by weight of ethanol are mixed in a container, finely dispersed in a Manton-Gaulin disperser having a shearing force of 30 MPa to obtain a fine particle stock solution, and diluted in a pressure-resistant closed container with 9 parts by weight of methylene chloride. This was used as a filler dispersion diluent.
[0153]
Dissolve 1.2 parts by mass of an ultraviolet absorber and 0.7 parts by mass of a cellulose ester (described in A of Table 1) in 14.2 parts by mass of methylene chloride, and dissolve 3.0 parts by mass of the filler dispersion diluent. Was added and stirred to obtain a filler-added liquid.
[0154]
The following cellulose ester solution composition was introduced into another pressure-tight container, and a cellulose ester solution was prepared by a high-temperature dissolution method. The pressure in the pressure-resistant closed vessel was set to 0.2 MPa, and the mixture was dissolved with stirring, and the filler-added solution having a mass ratio of 0.04 was poured into the cellulose ester solution having a mass ratio of 1, and the mixture was sufficiently stirred overnight. I left it. Thereafter, the solution was subjected to Azumi Filter Paper NO. Filtration was performed using 244 to prepare a dope.
[0155]
[Table 1]

[0156]
X: Degree of substitution of the substituent of the acetyl group
Y: degree of substitution of propionyl group and / or butyryl group
(Cellulose ester solution composition)
100 parts by mass of cellulose ester A (described in Table 1)
8.5 parts by mass of TPP
EPEG 2 parts by mass
300 parts by mass of methylene chloride
Ethanol 57 parts by mass
(Preparation of optically compensated cellulose ester film)
The temperature of the dope was adjusted to 35 ° C. and the temperature of the support was adjusted to 35 ° C. using the above-mentioned dope, and the solution was cast from a die onto a stainless steel support belt. The drying air temperature on the support was 40 ° C. Thereafter, the temperature of the support was set to 20 ° C., and the web was peeled off from the support at a residual solvent amount of 80% by mass. Next, while holding both ends of the web with clips using a tenter, the draw ratio, the web temperature during stretching, and the residual web content during stretching were changed to obtain a roll-shaped optically compensated cellulose ester film.
[0157]
(Production of viewing angle compensating polarizing plate)
Each of the optically compensated cellulose ester films was immersed in a 2 mol / L (liter) aqueous solution of sodium hydroxide at 60 ° C. for 2 minutes, washed with water, and then dried at 100 ° C. for 10 minutes to obtain an alkali-saponified polarizing plate protection. A film was prepared.
[0158]
Separately, a polyvinyl alcohol film having a thickness of 120 μm was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched 4 times at 50 ° C. to produce a polarizer (polarizing film).
[0159]
The optical compensation films were bonded to both sides of the polarizer using a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive to prepare a polarizing plate. At this time, bonding was performed such that the transmission axis of the polarizer and the slow axis of the optically-compensated cellulose ester film were parallel.
[0160]
The thicknesses (μm), Ro (nm), Rt (nm), tan δ (md), tan δ (td) and values of the ratios of the optical compensation films 1 to 6 for the viewing angle compensating polarizing plate produced by the above method. The evaluation results of reworkability and viewing angle characteristics are summarized in Table 2 below.
[0161]
[Table 2]

[0162]
As described above, the film of the present invention contributed to a reduction in thickness, and was able to achieve both reworkability and viewing angle characteristics.
[0163]
Example 2
An alkyl-modified polyvinyl alcohol (0.1 μm) is applied on one surface of the viewing angle compensating polarizing plate prepared as described above, and dried with hot air at 65 ° C., and then in the longitudinal direction of the film (the absorption axis direction of the polarizer). A rubbing treatment was performed in parallel with the above to form an alignment layer.
[0164]
Further, a solution LC-1 having the following composition is applied on the alignment layer, and 450 mJ / cm under an oxygen concentration of 0.1% or less.³And the optically anisotropic layer having a nematic hybrid structure was coated on one side to obtain a viewing angle compensating polarizing plate. Note that the above processing was performed by transporting a roll.
[0165]
When evaluation was performed in the same manner as in Example 1, the optical compensatory film of the present invention had good reworkability as in Example 1, and the effect of improving the viewing angle was larger. However, the evaluation was performed such that the optically anisotropic layer was attached to the cell side.
[0166]
(LC-1 solution)
MEK (methyl ethyl ketone) 88 parts by mass
Compound 1 3 parts by mass
Compound 2 3 parts by mass
Compound 3 3 parts by mass
Compound 4 2 parts by mass
Irgacure 369 (manufactured by Ciba Specialty Chemical) 1 part by mass
[0167]
Embedded image

[0168]
Example 3
The cellulose ester (described in A of Table 1) used in Example 1 was replaced with a cellulose ester having a degree of acetylation of 60% (described in B of Table 1), and the following compound (a retardation increasing agent) was further replaced by cellulose. A roll-shaped optical compensation film was obtained in the same manner except that 4 parts by mass was added to 100 parts by mass of the ester.
[0169]
Embedded image

[0170]
In the same manner as in Example 1 above, optical compensation films 11 to 16 for a viewing angle compensating polarizing plate were prepared and evaluated. The evaluation method, display method, and the like conform to Table 2.
[0171]
[Table 3]

[0172]
As described above, the film of the present invention contributed to a reduction in thickness, and was able to achieve both reworkability and viewing angle characteristics.
[0173]
Example 4
A rubbing treatment and an alignment layer were formed on the roll-shaped cellulose ester film obtained in Example 3 in the same manner as in Example 2.
[0174]
(Formation of optically anisotropic layer with discotic liquid crystalline compound)
On the alignment film, 41.01 g of the following discotic liquid crystalline compound, 4.06 g of ethylene oxide-modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.), and cellulose acetate butyrate (CAB551-0.2, 0.90 g of Eastman Chemical Co., Ltd., 0.23 g of cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co.), 1.35 g of photopolymerization initiator (Irgacure 907, Ciba Geigy), sensitizer ( A coating solution obtained by dissolving 0.45 g of Kayacure DETX (manufactured by Nippon Kayaku Co., Ltd.) in 102 g of methyl ethyl ketone was applied using a # 3.6 wire bar. This was heated in a constant temperature zone of 130 ° C. for 2 minutes to align the discotic liquid crystalline compound. Next, UV irradiation was performed for 1 minute in a 60 ° C. atmosphere using a 120 W / cm high-pressure mercury lamp to polymerize the discotic liquid crystalline compound. Then, it was allowed to cool to room temperature.
[0175]
Embedded image

[0176]
Evaluation was performed in the same manner as in Example 2. As a result, the optical compensation film of the present invention was able to achieve the effect of reducing the film thickness, improving reworkability, and improving the viewing angle.
[0177]
【The invention's effect】
According to the present invention, first, an optical compensation film having an excellent viewing angle compensation function can be provided. Secondly, the present invention provides a viewing angle compensation film that achieves a reduction in the thickness of a liquid crystal display device and further improves production yield and reworkability, a polarizing plate using the film, and a liquid crystal display device including the film. I can do it.

Claims (9)

A cellulose ester film having a film thickness of 10 to 70 μm, where tan δ (md) and tan δ (td) are respectively defined as tan δ (md) and tan δ (td) in the longitudinal and width directions of the cellulose ester film. ) Is in the range of 0.1 to 2.0, satisfies the relationship of tan δ (md)> tan δ (td), and Ro defined by the following formula (I) is in the range of 20 to 70 nm. Rt defined by the following formula (II) is 70 to 400 nm.
(I) Ro = (nx−ny) × d
(II) Rt = {(nx + ny) / 2−nz} × d
(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the film thickness direction, and d is the film index. Is the thickness.) 2. The optical compensation film according to claim 1, wherein the tan δ (md) and tan δ (td) satisfy a relationship of 0.5 <tan δ (td) / tan δ (md) <1.0. An optical compensation film, further comprising an optically anisotropic layer provided on the surface of the optical compensation film according to claim 1. The optical compensation film according to any one of claims 1 to 3, wherein the cellulose ester film satisfies the following formulas (III) and (IV) at the same time.
(III) 2.3 ≦ X + Y ≦ 2.85
(IV) 1.4 ≦ X ≦ 2.85
(However, X is the degree of substitution of the acetyl group, and Y is the degree of substitution of the propionyl group and / or the butyryl group.) The acetylation degree of the cellulose ester film is in the range of 59.0 to 61.5%, and the compound having at least two aromatic rings is contained in an amount of 0.01 to 20 parts by mass with respect to 100 parts by mass of the cellulose ester. The optical compensation film according to any one of claims 1 to 3, which is characterized in that: The optical compensation film according to claim 3, wherein the optically anisotropic layer has a fixed nematic hybrid alignment structure. The optical compensation film according to claim 3, wherein the optically anisotropic layer is a discotic liquid crystalline compound. In a polarizing plate comprising two protective films and a polarizer, at least one of the protective films is the optical compensation film according to any one of claims 1 to 7, and a cellulose ester film in the optical compensation film. A viewing angle compensating polarizing plate, wherein the slow axis and the transmission axis of the polarizer are substantially parallel. A liquid crystal display device using the viewing angle compensating polarizing plate according to claim 8.