JP2004212863A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device using polarizing plates which are expanded in angles of view, make it possible to improve a yield ratio in a blanking process of the polarizing films and are high in performance. <P>SOLUTION: The liquid crystal display device is constituted by laminating a first transparent protective film, the first polarizing film, a first transparent support, one or more first optically anisotropic layers formed of a liquid crystalline compound, a liquid crystal cell, one or more second optically anisotropic layers formed of the liquid crystalline compound, a second transparent support, the second polarizing film and a second transparent protective film in this order, in which the absorption axes of the first polarizing film and the second polarizing film are respectively not parallel and not perpendicular to the slow axes of the first transparent support and the second transparent support and the slow axis of the first transparent support and the slow axis of the second transparent support intersect orthogonally with each other. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０１１３】
式中、Ｌ^１１は、エーテル結合、ウレタン結合、アセタール結合またはエステル結合を表わし；Ｒ^１１は、アルキレン基またはアルキレンオキシ基を表わし；Ｌ^１２は、Ｒ^１１とＱ^１１とをつなぐ連結基を表わし；Ｑ^１１は、ビニル、オキシラニルまたはアジリジニルを表わし；ｘ１＋ｙ１＋ｚ１＝１００の条件にて、ｘ１は１０〜９９．９モル％、ｙ１は０．０１〜８０モル％、およびｚ１は０〜７０モル％であり；そしてｋおよびｈは、それぞれ０または１である。
【０１１４】
一般式（Ｉ）において、Ｒ^１１は、一般に炭素原子数１〜２４のアルキレン基、少なくとも一個の隣接しないＣＨ_２基が−Ｏ−、−ＣＯ−、−ＮＨ−、−ＮＲ^７−（Ｒ^７は炭素原子数１〜４のアルキルまたは炭素原子数６〜１５のアリールを表わす）、−Ｓ−、−ＳＯ_２−または炭素原子数６〜１５のアリーレンで置き換わった炭素原子数３〜２４のアルキレン基、またはアルキル、アリール、アルコキシ、アリーロキシ、アルキルチオ、アリールチオ、ハロゲン、アルキルカルボニル、アリールカルボニル、アルキルスルホニル、アリールスルホニル、ヒドロキシル、メルカプト、アミノ、アルキルカルボニルオキシ、アリールカルボニルオキシ、アルキルスルホニルオキシ、アリールスルホニルオキシ、アルキルカルボニルチオ、アリールカルボニルチオ、アルキルスルホニルチオ、アリールスルホニルチオ、アルキルカルボニルアミノ、アリールカルボニルアミノ、アルキルスルホニルアミノ、アリールスルホニルアミノ、カルボキシあるいはスルホで置換された上記アルキレン基いずれかを表わす。
【０１１５】
Ｒ^１１は、−Ｒ^２−、−Ｒ^３−（Ｏ−Ｒ^４）_ｔ−ＯＲ^５−、−Ｒ^３−ＣＯ−Ｒ^６−、−Ｒ^３−ＮＨ−Ｒ^６−、−Ｒ^３−ＮＲ^７−Ｒ^６−、−Ｒ^３−Ｓ−Ｒ^６−、−Ｒ^３−ＳＯ_２−Ｒ^６−または−Ｒ^３−Ａ^２−Ｒ^６−（但し、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５およびＲ^６は、それぞれ炭素原子数１〜２４のアルキレンを表わし、Ｒ^７は、炭素原子数１〜１２のアルキルまたは炭素原子数６〜１５のアリールを表わし、Ａ^２は炭素原子数６〜２４のアリーレンを表わし、そしてｔは、０〜４の整数を表わす）を表わすことが好ましい。さらに、Ｒ^１１は、−Ｒ^２−または−Ｒ^３−（Ｏ−ＣＨ_２ＣＨ_２）_ｔ−（但し、Ｒ^２およびＲ^３は、それぞれ炭素原子数１〜１２のアルキレンそしてｔは０〜２の整数である。）を表わすことが好ましく、特にＲ^１１は、炭素原子数１〜１２のアルキレンが好ましい。
【０１１６】
上記アルキレン基は置換基を有していても良い。その例としては、炭素原子数１〜２４のアルキル、炭素原子数６〜２４のアリール、炭素原子数１〜２４のアルコキシ、炭素原子数６〜２４のアリールオキシ、炭素原子数１〜２４のアルキルチオ、炭素原子数６〜２４のアリールチオ、ハロゲン（Ｆ、Ｃｌ、Ｂｒ）、炭素原子数２〜２４のアルキルカルボニル、炭素原子数７〜２４のアリールカルボニル、炭素原子数１〜２４のアルキルスルホニル、炭素原子数６〜２４のアリールスルホニル、ヒドロキシル、メルカプト、アミノ、炭素原子数２〜２４のアルキルカルボニルオキシ、炭素原子数７〜２４のアリールカルボニルオキシ、炭素原子数１〜２４のアルキルスルホニルオキシ、炭素原子数６〜２４のアリールスルホニルオキシ、炭素原子数２〜２４のアルキルカルボニルチオ、炭素原子数７〜２４のアリールカルボニルチオ、炭素原子数１〜２４のアルキルスルホニルチオ、炭素原子数６〜２４のアリールスルホニルチオ、炭素原子数２〜２４のアルキルカルボニルアミノ、炭素原子数７〜２４のアリールカルボニルアミノ、炭素原子数１〜２４のアルキルスルホニルアミノ、炭素原子数６〜２４のアリールスルホニルアミノ、カルボキシあるいはスルホを挙げることができる。
【０１１７】
上記アルキレン基の好ましい置換基としては、炭素原子数１〜２４のアルキル（特に炭素原子数１〜１２）、炭素原子数６〜２４のアリール（特に炭素原子数６〜１４）、炭素原子数２〜２４のアルコキシアルキル（特に炭素原子数２〜１２）を挙げることができる。アルキルの例としては、メチル、エチル、ｎ−ペンチル、ｎ−ヘキシル、ｎ−ヘプチル、ｎ−オクチル、ｎ−ノニル、ｎ−デシル、ｎ−ウンデシル、ｎ−ドデシル、ｉ−プロピル、ｉ−ブチル、ｓｅｃ−ブチル、ｔ−アミルおよび２−エチルヘキシルを挙げることができる。１〜４個のアルコキシで置換されたアルキルの例としては、２−メトキシエチル、２−（２−メトキシエトキシ）エチル、２−［２−（２−メトキシエトキシ）エトキシ］エチル、２−ｎ−ブトキシエチル、２−エトキシエチル、２−（２−エトキシエトキシ）エチル、３−メトキシプロピル、３−エトキシプロピル、３−ｎ−プロピルオキシプロピルおよび２−メチルブチルオキシメチルを挙げることができる。アリールの例としては、フェニル、２−トリル、３−トリル、４−トリル、２−アニシル、３−アニシル、４−アニシル、２−ビフェニル、３−ビフェニル、４−ビフェニル、２−クロロフェニル、３−クロロフェニル、４−クロロフェニル、１−ナフチルおよび２−ナフチルを挙げることができる。また、複素環基の例としては、ピリジル、ピリミジル、チアゾリルおよびオキサゾリルを挙げることができる。
【０１１８】
Ｌ^１２は、−Ｏ−、−Ｓ−、−ＣＯ−、−Ｏ−ＣＯ−、−ＣＯ−Ｏ−、−Ｏ−ＣＯ−Ｏ−、−ＣＯ−Ｏ−ＣＯ−、−ＮＲＣＯ−、−ＣＯＮＲ−、−ＮＲ−、−ＮＲＣＯＮＲ−、−ＮＲＣＯ−Ｏ−または−ＯＣＯＮＲ−（但し、Ｒは水素原子または低級アルキル基表わす）を表わすことが好ましい。−（Ｌ^１２）_ｈ−Ｑ^１２は、ビニル、ビニルオキシ、アクリロイル、メタクリロイル、クロトノイル、アクリロイルオキシ、メタクリロイルオキシ、クロトノイルオキシ、ビニルフェノキシ、ビニルベンゾイルオキシ、スチリル、１，２−エポキシエチル、１，２−エポキシプロピル、２，３−エポキシプロピル、１，２−イミノエチル、１，２−イミノプロピルまたは２，３−イミノプロピルであることが好ましい。更に、ビニル、ビニルオキシ、アクリロイル、メタクリロイル、アクリロイルオキシ、メタクリロイルオキシ、クロトノイルオキシ、ビニルベンゾイルオキシ、１，２−エポキシエチル、１，２−エポキシプロピル、２，３−エポキシプロピル、１，２−イミノエチル、１，２−イミノプロピルまたは２，３−イミノプロピルが好ましい。特に、アクリロイル、メタクリロイル、アクリロイルオキシおよびメタクリロイルオキシが好ましい。
【０１１９】
ｘ１＋ｙ１＋ｚ１＝１００の条件にて、ｘ１は５０〜９９．９モル％が好ましく、ｙ１は０．０１〜５０モル％が好ましく（さらに０．０１〜２０モル％が好ましく、特に０．０１〜１０モル％、最も好ましくは０．０１〜５モル％）およびｚ１は０．０１〜５０モル％が好ましい。
【０１２０】
上記一般式（Ｉ）においてＬ^１１がアセタール結合である場合、一般式（Ｉ）のポリビニルアルコールは、下記の一般式（Ｉａ）によって表わすことができる。
【０１２１】
【化２】

【０１２２】
式中、Ｌ^１１、Ｒ^１１、Ｌ^１２、Ｑ^１１、ｘ１、ｙ１、ｚ１、ｋおよびｈは、一般式（Ｉ）と同義である。
【０１２３】
配向膜用のポリビニルアルコールとしては、下記一般式（ＩＩＩ）で表されるものも好ましい。
【０１２４】
【化３】

【０１２５】
式中、Ｌ^３１は、エーテル結合、ウレタン結合、アセタール結合またはエステル結合を表わし；Ａ^３１は、アリーレン基、またはハロゲン、アルキル、アルコキシまたは置換アルコキシで置換されたアリーレン基を表わし（置換されたアルコキシの置換基としてはアルコキシ、アリール、ハロゲン、ビニル、ビニルオキシ、アクリロイル、メタアクリロイル、クロトノイル、アクリロイルオキシ、メタクリロイルオキシ、クロトノイルオキシ、ビニルフェノキシ、ビニルベンゾイルオキシ、スチリル、１，２−エポキシエチル、１，２−エポキシプロピル、２，３−エポキシプロピル、１，２−イミノエチル、１，２−イミノプロピルまたは２，３−イミノプロピルを挙げることができる）；Ｒ^３１は、Ｒ^１１と同一の基を表わし；Ｌ^３２は、Ｌ^１２と同一の基を表わし；Ｑ^３１は、Ｑ^１１と同一の基を表わし；ｘ２＋ｙ２＋ｚ２＝１００の条件にて、ｘ２は１０〜９９．９モル％、ｙ２は０．０１〜８０モル％、およびｚ２は０〜７０モル％であり；そしてｆ、ｋ１およびｈ１は、それぞれ０または１である。
特にＡ^３１は、炭素原子数６〜２４のアリーレン基、またはハロゲン、炭素原子数１〜４のアルキルあるいは炭素原子数１〜４のアルコキシで置換された炭素原子数６〜２４のアリーレン基であることが好ましい。
【０１２６】
Ａ^３１の基において、アリーレン基の炭素原子数は、一般に６〜２４個であり、６〜１２個が好ましい。アリーレン基の例としては、１，４−フェニレン、１，３−フェニレン、１，２−フェニレンおよび１，５−ナフチレンを挙げることができ、特に１，４−フェニレンが好ましい。アリーレン基の置換基としては、ハロゲン原子（Ｆ、Ｃｌ、ＢｒまたはＩ）、炭素原子数１〜４のアルキル基、炭素原子数１〜４のアルコキシ基、そして炭素原子数１〜４のアルコキシ、炭素原子数６〜１５のアリール、ハロゲン、ビニル、ビニルオキシ、オキシラニル（１，２−エポキシエチル、１，２−エポキシプロピル、２，３−エポキシプロピル）、アジリジニル（１，２−イミノエチル、１，２−イミノプロピルまたは２，３−イミノプロピル）、アクリロイル、メタクリロイル、クロトノイル、アクリロイルオキシ、メタクリロイルオキシ、クロトノイルオキシ、ビニルフェノキシ、ビニルベンゾイルオキシまたはスチリルで置換された炭素原子数１〜４のアルコキシ基を挙げることができる。好ましくは、ハロゲン原子、炭素原子数１〜４のアルキル基または炭素原子数１〜４のアルコキシ基であり、特にＦ、Ｃｌまたはメチルが好ましい。ｘ２＋ｙ２＋ｚ２＝１００の条件にて、ｘ２は５０〜９９．９モル％が好ましく、ｙ２は０．０１〜５０モル％が好ましく（特に０．０１〜２０モル％が好ましく、特に０．０１〜１０モル％、最も好ましくは０．０１〜５モル％）およびｚ２は０．０１〜５０モル％が好ましい。
【０１２７】
上記一般式（ＩＩＩ）においてＬ^３１がアセタール結合である場合、一般式（ＩＩＩ）のポリビニルアルコールは、下記の一般式（ＩＩＩａ）によって表わすことができる。
【０１２８】
【化４】

【０１２９】
式中、Ａ^３１、Ｒ^３１、Ｌ^３２、Ｑ^３１、ｘ２、ｙ２、ｚ２、ｆ、ｋ１およびｈ１は、一般式（ＩＩＩ）と同義である。
【０１３０】
更に、配向膜用のポリビニルアルコールとしては、その少なくとも一個のヒドロキシル基が下記の一般式（ＩＩ）の基で置換されたものであるものも好ましい。
【０１３１】
【化５】

【０１３２】
式中、Ｒ^２１は、アルキル基、またはアルキル、アルコキシ、アリル、ハロゲン、ビニル、ビニルオキシ、オキシラニル、アクリロイルオキシ、メタクリロイルオキシあるいはクロトノイルオキシで置換されたアルキル基を表わし；Ｗ^２１は、アルキル基、アルキル、アルコキシ、アリール、ハロゲン、ビニル、ビニルオキシ、オキシラニル、アクリロイルオキシ、メタクリロイルオキシあるいはクロトノイルオキシで置換されたアルキル基、アルコキシ基、またはアルキル、アルコキシ、アリール、ハロゲン、ビニル、ビニルオキシ、オキシラニル、アクリロイルオキシ、メタクリロイルオキシあるいはクロトノイルオキシで置換されたアルコキシ基を表わし；ｑは０または１であり；そしてｎは０〜４の整数である（好ましくは０または１で、特に０である）。
【０１３３】
Ｒ^２１が、アルキル基、またはアルキル、アルコキシ、アリールあるいはハロゲンで置換されたアルキル基を表わし；そしてＷ^２１は、アルキル基、アルキル、アルコキシ、アリールあるいはハロゲンで置換されたアルキル基、アルコキシ基、またはアルキル、アルコキシ、アリルあるいはハロゲンで置換されたアルコキシ基を表わすことが好ましい。
【０１３４】
また、Ｒ^２１が、ビニル、ビニルオキシ、オキシラニル、アクリロイルオキシ、メタクリロイルオキシあるいはクロトノイルオキシで置換されたアルキル基を表わし；そしてＷ^２１は、アルキル基、アルキル、アルコキシ、アリール、ハロゲン、ビニル、ビニルオキシ、オキシラニル、アクリロイルオキシ、メタクリロイルオキシあるいはクロトノイルオキシで置換されたアルキル基、アルコキシ基、またはアルキル、アルコキシ、アリール、ハロゲン、ビニル、ビニルオキシ、オキシラニル、アクリロイルオキシ、メタクリロイルオキシあるいはクロトノイルオキシで置換されたアルコキシ基を表わすことが好ましい。
【０１３５】
上記アルキル基またはアルコキシ基の炭素原子数は、１〜２４個が好ましく、特に１〜１２個が好ましい。上記アルキル基の例としては、無置換のアルキル基（例、メチル、エチル、ｎ−ペンチル、ｎ−ヘキシル、ｎ−ヘプチル、ｎ−オクチル、ｎ−ノニル、ｎ−デシル、ｎ−ウンデシル、ｎ−ドデシル、ｉ−プロピル、ｉ−ブチル、ｓｅｃ−ブチル、ｔ−アミルおよび２−エチルヘキシル）；１〜４のアルコキシで置換されたアルキル基（例えば、２−メトキシエチル、２−（２−メトキシエトキシ）エチル、２−［２−（２−メトキシエトキシ）エトキシ］エチル、２−ｎ−ブトキシエチル、２−エトキシエチル、２−（２−エトキシエトキシ）エチル、３−メトキシプロピル、３−エトキシプロピル、３−ｎ−プロピルオキシプロピル、３−ベンジルオキシプロピルおよび２−メチルブチルオキシメチル）；アラルキル基（例えば、２−フェニルエチルおよび２−（４−ｎ−ブチルオキシフェニル）エチル）；ビニルアルキル基（例えば、ビニルメチル、２−ビニルエチル、５−ビニルペンチル、６−ビニルヘキシル、７−ビニルヘプチルおよび８−ビニルオクチル）；ビニルオキシアルキル基（例えば、２−ビニルオキシエチル、５−ビニルオキシペンチル、６−ビニルオキシヘキシル、７−ビニルオキシヘプチルおよび８−ビニルオキシオクチル）；オキシラニルアルキル基（例えば、３，４−エポキシブチル、４，５−エポキシペンチル、５，６−エポキシヘキシル、６，７−エポキシヘプチル、７，８−エポキシオクチルおよび６，７−エポキシオクチル）；アクリロイルオキシアルキル基（例えば、２−アクリロイルオキシエチル、３−アクリロイルオキシプロピル、４−アクリロイルオキシブチル、５−アクリロイルオキシペンチル，６−アクリロイルオキシヘキシル、７−アクリロイルオキシヘプチルおよび８−アクリロイルオキシオクチル）；メタクリロイルオキシアルキル基（例えば、２−メタクリロイルオキシエチル、３−メタクリロイルオキシプロピル、４−メタクリロイルオキシブチル、５−メタクリロイルオキシペンチル，６−メタクリロイルオキシヘキシル、７−メタクリロイルオキシヘプチルおよび８−メタクリロイルオキシオクチル）；クロトノイルオキシアルキル基（例えば、２−クロトノイルオキシエチル、３−クロトノイルオキシプロピル、４−クロトノイルオキシブチル、５−クロトノイルオキシペンチル，６−クロトノイルオキシヘキシル、７−クロトノイルオキシヘプチルおよび８−クロトノイルオキシオクチル）を挙げることができる。
【０１３６】
ＯＲ^２１のベンゼン環との置換位置は３または４位が好ましい。上記一般式（ＩＩ）の基をもつポリビニルアルコールは、上記一般式（ＩＩ）の基をもつ繰り返す単位を、全繰り返し単位の０．１〜１０モル％の範囲（特に０．１〜５モル％の範囲）で有することが好ましい。
【０１３７】
前記一般式（ＩＩ）の基は、下記の一般式（ＩＩａ）の基を有するカルボン酸誘導体をポリビニルアルコールと反応させることにより、ポリビニルアルコールに導入することができる。
【０１３８】
【化６】

【０１３９】
一般式（ＩＩａ）において、Ｒ^２１、Ｗ^２１、ｎおよびｑは、前記一般式（ＩＩ）のものと同義であり、そしてＸは、カルボン酸部位活性化体を形成するに必要な（Ｘ−ＣＯ−を活性化させることができる）基を表わす。Ｘで表される基については、例えば泉屋信夫他著”ペプチド合成（第５章、丸善１９７５年刊）”に記載されている。例えば、活性エステルを形成する場合には、Ｘの例として、４−ニトロフェノキシ、Ｎ−オキシコハク酸イミドを挙げることができる。酸無水物を形成する場合には、対称型酸無水物および混合酸無水物を挙げることができ、混合酸無水物の場合のＸとしては、例えば、メタンスルホニルオキシ、トリフルオロアセチルオキシ、エチルオキシカルボニルオキシを挙げることができる。酸ハロゲン化物の場合のＸとしては、例えば、塩素原子、臭素原子を挙げることができる。これらの、Ｘで表される原子群を有する化合物は必ずしも単離される必要はなく、反応系中で生成されたものをそのまま使用してもよい。上記カルボン酸誘導体としては、混合酸無水物および酸ハロゲン化物が好ましく、メタンスルホニルオキシ型の混合酸無水物および酸塩化物が特に好ましい。
【０１４０】
前記一般式（Ｉ）、（ＩＩ）および（ＩＩＩ）、さらには（Ｉａ）、（ＩＩａ）および（ＩＩＩａ）で示したポリビニルアルコールの具体的な化合物としては、特開平９−１５２５０９号公報の段落００６０〜００６６および００７２〜００９５に記載の例示化合物が含まれる。また、その合成法については、上記公報の段落００７０および段落００９６〜０１２０に記載されている。
【０１４１】
本発明において、前記配向膜は、上記した特定のポリビニルアルコール単独からなるものでも、あるいは従来から知られている配向膜用ポリマーとの混合物からなるものでもよい。混合物の場合、一般に公知のポリマーを全ポリマーの９０質量％以下で使用することができるが、特に７０質量％以下で使用されることが好ましい。
【０１４２】
上記特定のポリビニルアルコール以外で、本発明において配向膜として使用可能な重合性基を有するポリマーの例として、ビニル、オキシラニルまたはアジリジニルを有するポリイミド、およびビニル、オキシラニルまたはアジリジニルを有するゼラチンを挙げることができる。これらのポリマーは、上記特定のポリビニルアルコールの合成と同様にして、ヒドロキシル基あるいはアミノ基が導入されたポリマーを用いて合成することができる。例えば、ポリイミドへの重合性基の導入は、ポリアミック酸のカルボキシル基に多価アルコールを反応させて、ポリアミック酸にヒドロキシル基を導入し、上記特定のポリビニルアルコールの合成で用いた重合性基を有する化合物（例えば、一般式（ＩＩａ）の化合物あるいはそのイソシアネート化合物）を上記ポリアミック酸のヒドロキシル基に反応させ、次いでこの重合性基を有するポリアミック酸を重合させることにより行なうことができる。ゼラチンへの重合性基の導入は、ゼラチンのリシン残基のε−アミノ基と上記特定のポリビニルアルコールの合成で用いた重合性基を有する化合物と反応させることにより行なうことができる。
【０１４３】
本発明の配向膜に使用することができる公知の他ポリマーの例としては、ポリメチルメタクリレート、アクリル酸／メタクリル酸共重合体、スチレン／マレインイミド共重合体、ポリビニルアルコールおよび変性ポリビニルアルコール、ポリ（Ｎ−メチロールアクリルアミド）、スチレン／ビニルトルエン共重合体、クロロスルホン化ポリエチレン、ニトロセルロース、ポリ塩化ビニル、塩素化ポリオレフィン、ポリエステル、ポリイミド、酢酸ビニル／塩化ビニル共重合体、エチレン／酢酸ビニル共重合体、カルボキシメチルセルロース、ポリエチレン、ポリプロピレンおよびポリカーボネートを挙げることができる。
【０１４４】
本発明において、前記配向膜は、配向膜形成材料である上記特定のポリビニルアルコールを含む塗布液を透明支持体上に塗布した後、加熱乾燥してポリマー層を形成し、そしてそのポリマー層をラビング処理等の配向処理を施すことにより形成することができる。塗布方法としては、スピンコーティング法、ディップコーティング法、エクストルージョンコーティング法およびバーコーティング法を挙げることができる。特にＥ型塗布法が好ましい。また、膜厚は０．１〜１０μｍが好ましい。加熱乾燥は２０℃ないし１１０℃で行なうことができ、特に６０℃〜１００℃が好ましく、特に８０℃〜１００℃が好ましい。乾燥時間は１分〜３６時間で行なうことができる。好ましくは５分間〜３０分間である。
【０１４５】
配向膜は、上記のようにポリマー層を、ＬＣＤの液晶配向処理工程として広く採用されている処理方法を利用して、ラビング処理する等の配向処理を施すことにより得ることができる。配向膜は、その上に設けられる液晶性ディスコティック化合物等の液晶性化合物の配向方向を規定するように機能する。前記ラビング処理は、一般にポリマー層の表面を、紙やガーゼ、フェルト、ゴムあるいはベルベット、ポリアミドやポリエステル等の繊維などを用いて一定方向に擦ることにより行なわれる。好ましくはベルベット等のラビング布が巻き付けられたラビングロールを用いてポリマー層表面を擦ることにより行なわれる。ラビングはバッチ法でも連続法で行なってもよい。
【０１４６】
本発明の液晶表示装置は、第１透明保護膜、第１偏光膜、第１透明支持体および第１光学異方性層、および／または、第２透明保護膜、第２偏光膜、第２透明支持体および第２光学異方性層を一体化した後、液晶セルと組み合わせて、作製することができる。
例えば、偏光膜を上述の連続的に行われる斜め延伸方法で作製した場合、長尺状の偏光膜が得られる。この長尺状の偏光膜をロール状に巻きつけてロール状偏光膜とし、一方、長尺状の透明支持体上に液晶性化合物からなる光学異方性層を形成し、ロール状に巻きつけた光学異方性層付きロール状透明支持体とし、これらを貼り合わせて連続的に一体化することによって、ロール状の積層体が得られる。このロール状の積層体を所望の大きさに裁断（打ち抜き）することにより、偏光膜、透明支持体および光学異方性層が一体化した部材が得られる。また、前記長尺状の偏光膜に、長尺状の透明保護膜を貼り合せると同時にまたは貼り合せた後に、長尺状の透明支持体上に液晶性化合物からなる１層以上の光学異方性層を形成した光学異方性層付き透明支持体を貼り合わせて積層体を得、これを所望の大きさに裁断（打ち抜き）することにより、透明保護膜、偏光膜、透明支持体および光学異方性層が一体化した部材が得られる。作製した一対の前記部材を、液晶セルを挟持して配置させることにより、本発明の液晶表示装置が作製できる。なお、本発明において、光学異方性層についてのレターデーション（Ｒｅ）値は、前記（１）式（請求項４中の（１）式）で定義することができる。
【０１４７】
【実施例】
以下に実施例を挙げて本発明をさらに具体的に説明する。以下の実施例に示す材料、試薬、割合、操作等は、本発明の精神から逸脱しない限り適宜変更することができる。従って、本発明の範囲は以下に示す具体例に制限されるものではない。
【０１４８】
［実施例１］
（透明支持体および透明保護膜用セルロースアセテートフィルムの作製）
下記の組成物をミキシングタンクに投入し、加熱しながら攪拌して、各成分を溶解し、セルロースアセテート溶液を調製した。
セルロースアセテート溶液組成
酢化度６０．７〜６１．１％のセルロースアセテート １００質量部
トリフェニルホスフェート（可塑剤） ７．８質量部
ビフェニルジフェニルホスフェート（可塑剤） ３．９質量部
メチレンクロライド（第１溶媒） ３３６質量部
メタノール（第２溶媒） ２９質量部
１−ブタノール（第３溶媒） １１質量部
【０１４９】
別のミキシングタンクに、下記のレターデーション上昇剤１６質量部、メチレンクロライド ９２質量部およびメタノール ８質量部を投入し、加熱しながら攪拌して、レターデーション上昇剤溶液を調製した。セルロースアセテート溶液４７４質量部にレターデーション上昇剤溶液２５質量部を混合し、充分に攪拌してドープを調製した。レターデーション上昇剤の添加量は、セルロースアセテート１００質量部に対して、３．５質量部であった。
【０１５０】
レターデーション上昇剤
【化７】

【０１５１】
得られたドープを、バンド延伸機を用いて流延した。バンド上での膜面温度が４０℃となってから、７０℃の温風で１分乾燥し、バンドからフィルムを１４０℃の乾燥風で１０分乾燥し、残留溶剤量が０．３質量％のセルロースアセテートフィルム（厚さ：６０μｍ）を作製した。作製したセルロースアセテートフィルム（透明支持体、透明保護膜）について、エリプソメーター（Ｍ−１５０、日本分光（株）製）を用いて、波長５４６ｎｍにおけるＲｅレターデーション値およびＲｔｈレターデーション値を測定した。Ｒｅは２ｎｍ（ばらつき±１ｎｍ）、Ｒｔｈは７８ｎｍ（ばらつき±３ｎｍ）であった。さらに、４００ｎｍ〜７００ｎｍの各波長のＲｅは２±１ｎｍ、４００ｎｍ〜７００ｎｍの各波長のＲｔｈは７８±２ｎｍの範囲であった。
作製したセルロースアセテートフィルムを２．０Ｎの水酸化カリウム溶液（２５℃）に２分間浸漬した後、硫酸で中和し、純水で水洗し、その後乾燥させた。このセルロースアセテートフィルムの表面エネルギーを接触法により求めたところ、６３ｍＮ／ｍであった。こうして、透明支持体用および透明保護膜用セルロースアセテートフィルムを作製した。
【０１５２】
（配向膜層の作製）
このセルロースアセテートフィルム上に、下記の組成の塗布液を＃１６のワイヤーバーコーターで２８ｍｌ／ｍ^２塗布した。２５℃で６０秒、６０℃の温風で６０秒、さらに９０℃の温風で１５０秒乾燥した。乾燥後の配向膜厚みは１．１μｍであった。また、配向膜の表面粗さ（Ｒａ）を原子間力顕微鏡（ＡＦＭ：Ａｔｏｍｉｃ Ｆｏｒｃｅ Ｍｉｃｒｏｓｃｏｐｅ、ＳＰＩ３８００Ｎ、セイコーインスツルメンツ（株）製）にて測定したところ、１．１４７ｎｍであった。次に、形成した膜に、セルロースアセテートフィルムの遅相軸（波長６３２．８ｎｍで測定）に対して４５°方向にラビング処理を実施した。
【０１５３】
配向膜塗布液組成
下記の変性ポリビニルアルコール ２０質量部
水 ３６１質量部
メタノール １１９質量部
グルタルアルデヒド（架橋剤） ０．５質量部
【０１５４】
変性ポリビニルアルコール
【化８】

【０１５５】
（光学異方性層の形成）
配向膜上に、液晶性ディスコティック化合物１，２，１’，２’，１’’，２’’−トリス［４、５−ジ（ビニルカルボニルオキシブトキシベンゾイルオキシ）フェニレン（特開平８−５０２０６号公報、段落００４４に記載の例示化合物ＴＥ−８の（８）、ｍ＝４）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（株）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（株）製）０．４５ｇを、１０２ｇのメチルエチルケトンに溶解した塗布液を、＃４のワイヤーバーで塗布した。これを金属の枠に貼り付けて、その後、１３０℃の恒温槽中で２分間加熱し、円盤状化合物を配向させた。次に、６０℃で１２０Ｗ／ｃｍ高圧水銀灯を用いて、１分間ＵＶ照射し円盤状化合物を重合させた。その後、室温まで放冷して、光学異方性層を形成した（膜厚１．９５μｍ）。
【０１５６】
作製した光学異方性層について、波長６３２．８ｎｍで測定したＲｅ（レターデーション値）は４６ｎｍであった。また、円盤面と第１透明支持体面との間の角度（傾斜角）は第一透明支持体側から空気界面に向かって増加（ハイブリッド配向）し、平均で３８゜であった。
また、光学異方性層の配向欠陥の数を１００倍のルーペを用いて観測したところ、７０μｍ以上の欠陥が１．３個／ｍ^２以下であった。
なお、光学異方性層についてのレターデーション（Ｒｅ）値は前記（１）式（請求項４中の（１）式）で定義することができる。
【０１５７】
（偏光膜の作製）
平均重合度が２，４００、膜厚１００μｍのＰＶＡフィルムを１５〜１７℃のイオン交換水にて６０秒洗浄し、ステンレス製のブレードにて表面水分を掻き取ったのち、該ＰＶＡフィルムを濃度が一定になるように濃度補正しつつヨウ素０．７７ｇ／ｌ、ヨウ化カリウム６０．０ｇ／ｌの水溶液に４０℃にて５５秒浸漬し、さらに濃度が一定になるように濃度補正しつつ硼酸４２．５ｇ／ｌ、ヨウ化カリウム３０ｇ／ｌ、塩化亜鉛１．８ｇ／ｌの水溶液に４０℃にて９０秒浸漬後、フィルムの両面をステンレス製ブレードにて余剰水分を掻き取り、フィルム中の含有水分率の分布を２％以下にした状態（この時のＰＶＡフィルムの平均含有水分率は３２％であった）で、図４の形態のテンター延伸機に導入した。搬送速度を４ｍ／分として、１００ｍ送出し、６０℃９５％雰囲気下で５倍まで延伸した後、テンターを延伸方向に対し図４の如く屈曲させ、以降幅を一定に保ち、収縮させながら７０℃雰囲気で乾燥させた後テンターから離脱した。乾燥後のＰＶＡフィルムの含有水分率は１．５％であった。左右のテンタークリップの搬送速度差は、０．０５％未満であり、導入されるフィルムの中心線と次工程に送られるフィルムの中心線のなす角は、４６゜であった。ここで｜Ｌ１−Ｌ２｜は０．７ｍ、Ｗは０．７ｍであり、｜Ｌ１−Ｌ２｜＝Ｗの関係にあった。テンター出口における実質延伸方向Ａｘ−Ｃｘは、次工程へ送られるフィルムの中心線２２に対し４５゜傾斜していた。テンター出口におけるシワ、フィルム変形は観察されなかった。なお、延伸、乾燥後のフィルムの厚さは１９μｍであった。
【０１５８】
（透明保護膜の貼り合わせ）
上記の斜め延伸した偏光膜を幅方向から３ｃｍ、カッターにて耳きりをした後、その両面をＰＶＡ（（株）クラレ製ＰＶＡ−１１７Ｈ）３％水溶液を接着剤として、ケン化処理した上記光学異方性層を有する透明支持体およびケン化処理した上記で作製した透明保護膜用セルロースアセテートフィルムを貼り合わせ、さらに７０℃で１０分間加熱して有効幅６５０ｍｍの両面にセルロースアセテートフィルムを供えた偏光板を得た。
上記偏光板の光学異方性層を除いた偏光板性能は、可視光透過率が４３．２で、偏光度｛（Ｔｐ−Ｔｃ）／（Ｔｐ＋Ｔｃ）｝^１／２が０．９９９７（ただし、Ｔｐは平行透過率、Ｔｃは直交透過率）であり、６０℃、湿度９０％ＲＨ雰囲気下に５００時間および８０℃、ドライ雰囲気下に５００時間放置した場合のその前後における光透過率の変化率が絶対値に基づいて１％以下、偏光度の変化率は絶対値に基づいて０．０５％以下であった。
【０１５９】
得られた偏光膜の吸収軸方向は、長手方向に対し４５゜傾斜していた。この偏光板の５５０ｎｍにおける透過率は４２．３％、偏光度は９９．９７％であった。さらに図１０の如く３１０×２３３ｍｍサイズに裁断したところ、９１．５％の面積効率で辺に対し４５゜吸収軸が傾斜した偏光板を得ることができた。また、目視にて色抜けスジは見られなかった。
【０１６０】
（液晶セルとの積層配置）
市販の液晶表示装置（６Ｅ−Ａ３、シャープ（株）製）から偏光板を剥してＴＮ型液晶セルを取り出して、上記で作製した偏光板を、図１および図２に示す配置で液晶セルと積層した。具体的には、第１透明保護膜の遅相軸（フィルムの長手方向）と第１偏光膜吸収軸のなす角度を＋４５°、同じく第１透明支持体の遅相軸（フィルムの長手方向）と第１偏光膜吸収軸のなす角度を＋４５°、第１偏光膜吸収軸とディスコティック液晶性化合物からなる第１光学異方性層の配向制御方向（ラビング角度）のなす角度を０°あるいは１８０°とした。また液晶セルの上側ラビング軸６と第１透明保護膜の遅相軸４のなす角度 は＋４５°あるいは−４５°とした。同様に第２透明保護膜の遅相軸（フィルムの長手方向）と第２偏光膜吸収軸のなす角度を＋４５°、同じく第２透明支持体の遅相軸（フィルムの長手方向）と第２偏光膜吸収軸のなす角度を＋４５°、第２偏光膜吸収軸とディスコティック液晶性化合物からなる第２光学異方性層の配向制御方向（ラビング角度）のなす角度を０°あるいは１８０°とした。また液晶セルの下側ラビング軸と第２透明保護膜の遅相軸のなす角度を＋４５°あるいは−４５°とした。
なお、液晶セルラビング軸と透明支持体の遅相軸（フィルムの長手方向）のなす角度は、液晶セルツイスト角度や液晶セル駆動電圧によって、最大コントラストを達成する最適角度が変化するためこの角度に限定されることはない。さらに第１偏光膜吸収軸と第２偏光膜吸収軸のなす角度は９０°とした。このようにして作製した液晶セルを、前述の液晶表示装置（６Ｅ−Ａ３、シャープ（株）製）に戻して、第２透明保護層をバックライト側にして液晶表示装置５を作製した。以上の角度は、液晶セルやディスコティック液晶性化合物からなる光学異方性層の形成プロセスの変動を考慮すると、プラスマイナス５°前後のずれは許容される。
【０１６１】
（視野角測定）
作製した液晶表示装置の輝度およびコントラスト比は分光放射輝度計（トプコン社製のＢＭ−５）で測定した。コントラスト比は白表示輝度と黒表示輝度の比から算出した。また視野角は抑角５°毎、方位角は１０°毎に暗室下で測定した。結果をグラフに表す時は同じコントラストの値の角度を実線で結んだ等コントラスト曲線図を用いた。
【０１６２】
（第１透明支持体の遅相軸と第１偏光膜の吸収軸がなす角度４５°からのずれ（軸ずれ）の視野角に与える影響についての評価）
第１透明支持体の遅相軸の方向を変えた以外は、液晶表示装置５と同様にして、表１に示す液晶表示装置１〜４および６〜９を作製した。液晶表示装置１〜９について、正面コントラスト比と左右方向視野角でコントラスト比１０対１以上の範囲の測定結果を表１にあわせて示す。表１の結果より軸ずれ角度±５°であれば同じ特性であり、本発明が有効であることがわかる。また、±５°前後のずれは許容されることもわかる。なお、第２透明支持体の遅相軸と第２偏光膜の軸ずれの場合も同様な結果であった。
【０１６３】
【表１】

【０１６４】
［実施例２］
＜第１および第２透明支持体のＲｅ値の影響の測定結果＞
表２に示す様に、第１および第２透明支持体のＲｅ値の値を変えた以外は、液晶表示装置５と同様にして、液晶表示装置１０〜１４を作製した。なお、Ｒｅ値の調整はフィルムの厚さと延伸強さ、添加剤等で制御を行い、Ｒｔｈは７８ｎｍで一定になるようにした。液晶表示装置５、１０〜１４について、液晶表示装置正面コントラスト比と左右方向視野角でコントラスト比１０対１以上の範囲の測定結果を表２にあわせて示す。
表２に示す結果より、透明支持体のＲｅ値が大きくなるにつれて視野角は悪化し、特に左右方向でコントラスト比１０対１以上の範囲が狭くなることがわかる。また、左方向と右方向のコントラスト１０対１以上の範囲の対称性も悪化する。透明支持体のＲｅ値が５ｎｍよりも大きくなるとその範囲の差に１０°以上の開きが生じ、目視観察においても視野角の非対称性や劣化が確認された。
【０１６５】
【表２】

【０１６６】
［実施例３］
＜透明支持体のＲｔｈ値の影響の測定結果＞
表３に示す様に、第２透明支持体のＲｔｈの値は７８ｎｍとし、第１透明支持体のＲｔｈ値の値を変えた以外は、液晶表示装置５と同様にして、液晶表示装置１５〜１８を作製した。なお、Ｒｔｈ値の調整はフィルムの厚さと延伸強さ、添加剤等で制御を行い、Ｒｅは２ｎｍで一定になるようにした。表３に保護フィルムＲｔｈ値の値を変えたそれぞれの液晶表示装置について、正面コントラスト比と左右方向視野角でコントラスト比１０対１以上となる視野角の測定結果を示す。同表の結果よりＲｔｈ値の大きさは７６ｎｍ±５ｎｍであれば同じ特性であった。また、Ｒｔｈを大きく変えた場合は、コントラスト１０：１以上の範囲が左右方向で５０°以上得るためには、Ｒｔｈを５０〜２００ｎｍの間に設定すればよい。なお、このときのＲｅ値は２ｎｍのフィルムを用いた。
【０１６７】
【表３】

【０１６８】
［実施例４］
（第１透明支持体および第２透明支持体のＲｅ値ずれの影響の測定結果）
表４に示す様に、光学異方性層の塗布量を変えて光学異方性層の厚みを１．４３μｍ（Ｒｅ値は４６ｎｍ、円盤面と第１透明支持体面との間の角度（傾斜角）は平均で３９゜）にし、第１透明支持体および第２透明支持体のＲｅ値を表４のように変化させた以外は液晶表示装置５と同じ作製にした液晶表示装置を作製した。なお、このときの第１透明支持体および第２透明支持体のＲｔｈは７８ｎｍであった。得られた液晶表示装置の正面コントラスト比の測定結果を表４にあわせて示す。表４の結果より第１透明支持体と第２透明支持体のＲｅ値に差が生じると正面コントラストは低下する。１０００対１以上の高コントラストを得るには、第１透明支持体と第２透明支持体のＲｅ値の差は±３ｎｍ以内が必要である。またＲｅ値の絶対値が大きくなると視野角特性の非対称性が顕著になるため、Ｒｅの絶対値は５ｎｍ以下にすることが望ましい。
【０１６９】
【表４】

【０１７０】
［実施例５］
実施例１の第１透明保護膜および第２透明保護膜を市販のセルローストリアセテートフフィルム（フジタックＴＤ８０ＵＦ、富士写真フイルム（株）製）にけん化処理したものに替えた以外は、液晶表示装置１〜９と同様に液晶表示装置を作製し、実施例１と同様な評価を行なった。得られた結果は実施例１とほぼ同じ結果となった。
また、実施例１と同様に、上記に用いた偏光板の光学異方性層を除いた偏光板性能を評価した。結果は、可視光透過率が４３．６で、偏光度｛（Ｔｐ−Ｔｃ）／（Ｔｐ＋Ｔｃ）｝^１／２が０．９９９６（ただし、Ｔｐは平行透過率、Ｔｃは直交透過率）であり、６０℃、湿度９０％ＲＨ雰囲気下に５００時間および８０℃、ドライ雰囲気下に５００時間放置した場合のその前後における光透過率の変化率が絶対値に基づいて１％以下、偏光度の変化率は絶対値に基づいて０．０５％以下であった。
【０１７１】
［比較例１］
第１透明保護膜及び第１透明支持体の遅相軸と第１偏光膜吸収軸のなす角度は概略平行にし、かつ第２透明保護膜及び第２透明支持体の遅相軸と第２偏光膜吸収軸のなす角度は概略平行にし、他の構成は実施例１と同じにした。液晶表示装置のコントラスト比１０対１以上の視野角は左右方向ともに７０°以上、正面コントラスト比１２００が得られたが、偏光板をロールから切り出す場合にこの構成では得率が低下することがわかった。
【０１７２】
【発明の効果】
本発明によれば、視野角が拡大され、しかも安価に製造できる偏光板を用いることにより、製造コストを格段に軽減できる液晶表示装置を提供することであり、特に、打ち抜き工程における得率の向上が可能な偏光板を用いた、視野角の拡大された液晶表示装置を提供することにある。
【図面の簡単な説明】
【図１】本発明の液晶表示装置の例を示す概略図である。
【図２】本発明の偏光板の例を示す概略図である。
【図３】ポリマーフィルムを斜め延伸する本発明の方法の一例を示す概略平面図である。
【図４】ポリマーフィルムを斜め延伸する本発明の方法の一例を示す概略平面図である。
【図５】ポリマーフィルムを斜め延伸する本発明の方法の一例を示す概略平面図である。
【図６】ポリマーフィルムを斜め延伸する本発明の方法の一例を示す概略平面図である。
【図７】ポリマーフィルムを斜め延伸する本発明の方法の一例を示す概略平面図である。
【図８】ポリマーフィルムを斜め延伸する本発明の方法の一例を示す概略平面図である。
【図９】従来の偏光板を打ち抜く様子を示す概略平面図である。
【図１０】本発明の偏光板を打ち抜く様子を示す概略平面図である。
【符号の説明】
１Ａ 第１偏光板（第１透明保護膜、第１偏光膜、第１支持体の順からなる）
２Ａ 第１偏光板の吸収軸
３Ａ 第１光学異方性層
４Ａ 第１光学異方性層の配向制御方向
５Ａ 液晶セル観察側基板
６Ａ 観察側基板液晶配向用ラビング方向
７Ａ 液晶分子
８Ａ 液晶セルバックライト側基板
９Ａ バックライト側基板液晶配向用ラビング方向
１０Ａ 第２光学異方性層
１１Ａ 第２光学異方性層の配向制御方向
１２Ａ 透明保護膜
１３Ａ 透明保護膜遅相軸
１４Ａ 偏光板偏光膜
１５Ａ 偏光膜吸収軸
１６Ａ 遅相軸と吸収軸の交差角
１７Ａ 透明支持体
１８Ａ 透明支持体遅相軸
１９Ａ 第２偏光板（第２支持体、第２偏光膜、第２透明保護膜の順からなる）
２０Ａ 第２偏光板の吸収軸
（イ） フィルム導入方向
（ロ） 次工程へのフィルム搬送方向
（ａ） フィルムを導入する工程
（ｂ） フィルムを延伸する工程
（ｃ） 延伸フィルムを次工程へ送る工程
Ａ１ フィルムの保持手段への噛み込み位置とフィルム延伸の起点位置（実質保持開始点：右）
Ｂ１ フィルムの保持手段への噛み込み位置（左）
Ｃ１ フィルム延伸の起点位置（実質保持開始点：左）
Ｃｘ フィルム離脱位置とフィルム延伸の終点基準位置（実質保持解除点：左）
Ａｙ フィルム延伸の終点基準位置（実質保持解除点：右）
｜Ｌ１−Ｌ２｜ 左右のフィルム保持手段の行程差
Ｗ フィルムの延伸工程終端における実質幅
θ 延伸方向とフィルム進行方向のなす角
１１ 導入側フィルムの中央線
１２ 次工程に送られるフィルムの中央線
１３ フィルム保持手段の軌跡（左）
１４ フィルム保持手段の軌跡（右）
１５ 導入側フィルム
１６ 次工程に送られるフィルム
１７、１７’左右のフィルム保持開始（噛み込み）点
１８、１８’左右のフィルム保持手段からの離脱点
２１ 導入側フィルムの中央線
２２ 次工程に送られるフィルムの中央線
２３ フィルム保持手段の軌跡（左）
２４ フィルム保持手段の軌跡（右）
２５ 導入側フィルム
２６ 次工程に送られるフィルム
２７、２７’左右のフィルム保持開始（噛み込み）点
２８、２８’左右のフィルム保持手段からの離脱点
３３、４３、５３、６３ フィルム保持手段の軌跡（左）
３４、４４、５４、６４ フィルム保持手段の軌跡（右）
３５、４５、５５、６５ 導入側フィルム
３６、４６、５６、６６ 次工程に送られるフィルム
７１ 吸収軸（延伸軸）
７２ 長手方向
８１ 吸収軸（延伸軸）
８２ 長手方向[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device using a polarizing plate with a viewing angle widening function. Specifically, the present invention relates to a liquid crystal display device using a polarizing film including a polarizing film having a high yield and excellent polarizing performance, an optically anisotropic layer having a wide viewing angle, a transparent support, and a transparent protective film.
[0002]
[Prior art]
The demand for polarizing plates is rapidly increasing with the spread of liquid crystal display devices (hereinafter sometimes referred to as “LCD”). In general, a polarizing plate has a transparent protective film bonded to both sides or one side of a polarizing film having polarizing ability via an adhesive layer. As a material for the polarizing film, polyvinyl alcohol (hereinafter referred to as PVA) is mainly used. After the PVA film is uniaxially stretched, it is dyed with iodine or a dichroic dye or dyed, and then stretched. A polarizing film is formed by crosslinking with a compound. As the transparent protective film, cellulose triacetate is mainly used because it is optically transparent and has a small birefringence. Since the polarizing film is usually produced by uniaxial stretching in the running direction (longitudinal direction) of the continuous film, the absorption axis of the polarizing film is substantially parallel to the longitudinal direction.
[0003]
Recently, LCDs are widely used in place of CRTs due to their thinness and light weight and low power consumption. The optical rotation mode LCDs such as TFT-LCD and MIM-LCD which are widely used are advantageous in many respects compared with the birefringence mode and other modes. However, since the display color and the display contrast change depending on the angle when viewing the liquid crystal display device (viewing angle characteristics), the display characteristics do not reach the CRT level.
[0004]
Technical development for improving the viewing angle characteristics (that is, widening the viewing angle) is a retardation plate (optical compensation sheet) provided between a pair of polarizing plates and a liquid crystal cell (for example, Patent Document 1). And 2) obtained by applying an optical compensation sheet having negative birefringence and an inclined optical axis (for example, Patent Documents 3 and 4) and a polymer having liquid crystal properties to the surface of the alignment film on the support film. Various optical compensation sheets (for example, Patent Documents 5 and 6) and optical compensation sheets (for example, Patent Document 7) made of a polymerizable rod-like compound having liquid crystallinity and positive birefringence have been proposed. Thus, there has been a strong demand for widening the viewing angle as a practical performance of LCDs.
[0005]
Under such circumstances, the optically anisotropic layer is made of a compound having a discotic structure and the disk surface thereof changes (for example, Patent Document 8), and the liquid crystalline compound and the oriented polymer are chemically treated at the interface. It is disclosed that an optically compensatory sheet (for example, Patent Document 9) that is bonded together is extremely excellent in its viewing angle expansion capability and durability. One of the advantages of these disclosed optical compensatory sheets is that they are easy to manufacture, but as the use of polarizing plates for LCDs expands, development of a method that can be manufactured at a lower cost is also desired. ing.
[0006]
In the conventional LCD, the transmission axis of the polarizing plate is inclined by 45 ° with respect to the vertical or horizontal direction of the screen. Therefore, in the punching process of the polarizing plate manufactured in a roll form, It was necessary to punch in the direction. However, when it is punched in the direction of 45 °, there is a portion that cannot be used near the end of the roll, and there is a problem that the yield is reduced particularly in a large size polarizing plate, resulting in an increase in waste. .
[0007]
In order to solve this problem, several methods have been proposed in which the orientation axis of the polymer constituting the film is inclined by a desired angle with respect to the longitudinal direction of the film for the polarizing film. The plastic film is stretched uniaxially in the horizontal or vertical direction, and the right and left sides of the stretching direction are stretched at different speeds in the vertical or horizontal direction different from the stretching direction to tilt the orientation axis with respect to the uniaxial stretching direction. Has been proposed (for example, Patent Document 10). However, in this method, for example, when the tenter method is used, a difference in transport speed must be made between the left and right, resulting in creases and film shifts resulting in a desired tilt angle (45 ° for a polarizing plate). Is difficult. If an attempt is made to reduce the left-right speed difference, the stretching process must be lengthened, and the equipment cost becomes very large.
[0008]
Also, there are a plurality of pairs of left and right film holding points that form a certain angle with the traveling direction at the left and right ear ends of the continuous film (long film), and each pair point is in the direction of the angle as the film travels. A method of manufacturing a film having a stretching axis having a specific angle with respect to the traveling direction of the film has been proposed (for example, Patent Document 11). However, even in this method, since the film traveling speed changes depending on the right and left of the film, the film is creased and wrinkled. In order to alleviate this, there is a disadvantage that the stretching process needs to be very long and the equipment cost increases. It was.
[0009]
Furthermore, the both ends of the film are gripped and moved between two rows of chucks that run on tenter rails that are arranged so that the running distances of the chucks in the predetermined running section are different, and the film is inclined with respect to the length direction of the film. A manufacturing method that extends in the intersecting direction has been proposed (for example, Patent Document 12). However, even in this method, slipping and wrinkling occurred when obliquely crossed, which was inconvenient for an optical film.
As described above, coexistence between the reduction in the punching loss of the long polarizing plate and the quality such as the planar characteristics of the polarizing plate has not been realized.
[0010]
On the other hand, a transparent protective film used for a polarizing plate, particularly a polymer film for a transparent support having an optically anisotropic layer, has a high transmittance so as not to affect light transmission or polarization, A polymer film having a small retardation is preferred. However, even though the conventional transparent support has “small retardation in the film surface”, the range thereof is various and sometimes has a retardation of several tens of nm. There was also in-plane variation in phase difference. As for the retardation in the thickness direction, the preferable range is almost always described in a wide range of several hundred nm (for example, Patent Document 13), and the variation is not specified. For this reason, display unevenness, partial coloration, and viewing angle become narrow when using a conventional transparent support or a conventional lamination method, particularly when the absorption axis of the polarizing plate is neither parallel nor perpendicular to the slow axis of the transparent support. I found out there was a problem.
[0011]
[Patent Document 1]
JP-A-4-229828
[Patent Document 2]
JP-A-4-258923
[Patent Document 3]
JP-A-6-75115
[Patent Document 4]
European Patent No. 0576304A1
[Patent Document 5]
Japanese Patent Laid-Open No. 3-9326
[Patent Document 6]
JP-A-3-291601
[Patent Document 7]
Japanese Patent Application Laid-Open No. 5-215921
[Patent Document 8]
JP-A-8-50206
[Patent Document 9]
JP 9-152509 A
[Patent Document 10]
Japanese Patent Laid-Open No. 2000-9912
[Patent Document 11]
Japanese Patent Laid-Open No. 3-182701
[Patent Document 12]
Japanese Patent Laid-Open No. 2-113920
[Patent Document 13]
JP 2001-129927 A
[0012]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a liquid crystal display device that can significantly reduce the manufacturing cost by using a polarizing plate that has a wide viewing angle and can be manufactured at low cost. An object of the present invention is to provide a liquid crystal display device having a wide viewing angle using a polarizing plate capable of improving the yield.
[0013]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, as a result of intensive studies on polarizing plates that have excellent performance while having an oblique orientation, transparent protection that can greatly contribute to manufacturing yield while maintaining the viewing angle expansion function and polarization performance A novel configuration including a film, a polarizing film, an optically anisotropic layer and a transparent support has been obtained, and the present invention has been achieved.
[0014]
That is, the means for solving the problems are as follows.
(1) formed of a first transparent protective film, a first polarizing film, a first transparent support, a first optically anisotropic layer composed of one or more layers formed from a liquid crystalline compound, a liquid crystal cell, and a liquid crystalline compound A second optically anisotropic layer composed of one or more layers, a second transparent support, a second polarizing film, and a second transparent protective film are laminated in this order, and the absorption axes of the first polarizing film and the second polarizing film are The slow axis of the first transparent support and the second transparent support are neither parallel nor perpendicular to each other, and the slow axis of the first transparent support and the slow axis of the second transparent support are orthogonal to each other. A liquid crystal display device.
(2) At least one of the first optical anisotropic layer and the second optical anisotropic layer is a layer made of a compound having a discotic structural unit, and the disc surface of the discotic structural unit is a transparent support surface. The liquid crystal according to (1), wherein the liquid crystal layer is inclined with respect to the discotic structural unit, and an angle formed by the disc surface of the discotic structural unit and the transparent support surface changes in the thickness direction of the optically anisotropic layer. Display device.
[0015]
(3) The crossing angle between the slow axis of the first transparent support and the absorption axis of the first polarizing film is 10 ° or more and less than 90 °, and the slow axis of the second transparent support and the absorption of the second polarizing film The liquid crystal display device according to (1) or (2), wherein an intersection angle with an axis is 10 ° or more and less than 90 °.
(4) The liquid crystal according to any one of (1) to (3), wherein at least one of the first transparent support and the second transparent support satisfies the following conditions (A) to (C): Display device.
(A) Re (retardation) value represented by the following formula (1) is -5 nm or more and 5 nm or less, and the variation in Re is ± 3 nm or less of the average value.
Re value = (nx−ny) × d (1)
(B) The Rth value represented by the following formula (2) is 50 nm or more and 200 nm or less, and the variation of Rth is ± 5 nm or less of the average value.
Rth value = {(nx + ny) / 2−nz} × d (2)
(Where nx is the refractive index in the slow axis direction in the plane of the transparent support, ny is the refractive index in the direction perpendicular to nx in the plane of the transparent support, and nz is the refractive index in the thickness direction of the transparent support) D represents the thickness of the transparent support)
(C) Thickness 20 μm or more and 100 μm or less
[0016]
(5) The Re (retardation) value of 400 nm to 700 nm of at least one of the first transparent support and the second transparent support is ± 2 nm or less with respect to the Re average value of 400 nm to 700 nm. The liquid crystal display device according to (4).
(6) The Rth value of 400 nm to 700 nm of at least one of the first transparent support and the second transparent support is ± 3 nm or less with respect to the Rth average value of 400 nm to 700 nm (4) or The liquid crystal display device according to (5).
(7) At least one of a 1st transparent support body and a 2nd transparent support body consists of a cellulose acylate film, The liquid crystal display device in any one of (1)-(6) characterized by the above-mentioned.
(8) At least one of the first polarizing film and the second polarizing film holds both ends of the continuously supplied polymer film by the holding means, and the holding means is the length of the film under the condition satisfying the following formula (3) The film is stretched by applying a tension while proceeding in the direction, and is formed by cutting a long polarizing film produced by making the difference in the conveyance speed between the left and right in the longitudinal direction of the stretched film less than 1%. The liquid crystal display device according to any one of (1) to (7).
| L2-L1 |> 0.4W (3)
(In the formula (3), L1 represents the trajectory of the holding means from the substantial holding start point to the substantial releasing point of the one end of the polymer film; L2 represents the substantial other end of the polymer film; The holding means trajectory from the initial holding start point to the substantial holding release point; and W denotes the distance between the two substantially holding release points.)
[0017]
(9) The volatile fraction before stretching of the polymer film is 10% or more, and the elongated polarizing film is contracted by 10% or more after stretching the polymer film 2 to 10 times. (8) The liquid crystal display device according to (8).
(10) The liquid crystal display device according to (8) or (9), wherein the polymer film is made of a polyvinyl alcohol-based polymer, and the thickness before stretching is 75 μm to 200 μm.
(11) In any one of (8) to (10), the long polarizing film is produced by adsorbing a polarizing element on a polyvinyl alcohol polymer film before or after stretching. The liquid crystal display device described.
(12) At least the first polarizing film, the first transparent support and the first optical anisotropic layer, and / or the second polarizing film, the second transparent support and the second optical anisotropic layer are the long A long polarizing film and a transparent support with a long optical anisotropic layer in which one or more optical anisotropic layers made of a liquid crystalline compound are formed on a long transparent support The liquid crystal display device according to any one of (8) to (11), which is formed by cutting a long laminated body integrated together.
(13) At least the first transparent protective film and the first polarizing film, and / or the second transparent protective film and the second polarizing film stretch and shrink the polymer film, and further reduce the volatile content rate. (8) to (12), which is obtained by pasting a long transparent protective film on the produced long polarizing film and then cutting the long laminate obtained by post-heating. The liquid crystal display device according to any one of the above.
(14) First transparent protective film, first polarizing film, first transparent support and first optical anisotropic layer, and / or second transparent protective film, second polarizing film, second transparent support and first 2 An optically anisotropic layer stretches the polymer film, shrinks it, and further adheres a long transparent protective film to a long polarizing film produced by reducing the volatile content rate, or at the same time. After combining, a laminate in which a long transparent support with an optically anisotropic layer in which one or more optically anisotropic layers made of a liquid crystalline compound are formed on a long transparent support is bonded. The liquid crystal display device according to any one of (8) to (13), which is cut.
(15) The liquid crystal display device according to any one of (1) to (14), wherein the liquid crystal cell is a TN mode or OCB mode liquid crystal cell.
[0018]
In the present specification, “45 °”, “parallel” or “orthogonal” means that the angle is within a range of strictly less than ± 5 °. The error from the exact angle is preferably less than 4 °, more preferably less than 3 °. Further, the “slow axis” means a direction in which the refractive index is maximized.
[0019]
The liquid crystal display device according to the present invention includes a transparent protective film, a polarizing film having a polarizing ability, a transparent support, and an optically anisotropic layer having a function of expanding a field of view, which are disposed with a liquid crystal cell interposed therebetween. Two stacked structures stacked in this order are included. This laminated structure functions as a polarizing plate. A polarizing plate is usually obtained by producing a long polarizing plate (usually in the form of a roll) and punching it out for use. Alternatively, one or two members of a transparent protective film, a polarizing film having polarizing ability, a transparent support, and an optically anisotropic layer having a function of expanding the viewing angle can be manufactured in a long shape to suit the application. It is obtained by punching and then bonding. In this specification, unless otherwise specified, “polarizing plate” is cut into a size to be incorporated into a long polarizing plate and a liquid crystal device (in this specification, “cutting” includes “punching”, “cutting”, etc. It is also used to include both polarizing plates. In the present specification, “polarizing film” and “polarizing plate” are distinguished from each other, but “polarizing plate” is a transparent protective film that protects the polarizing film on at least one side of “polarizing film” (in the case of a transparent support). It is also meant to be a laminate having
[0020]
In the present invention, a liquid crystal display device has a high performance by using a laminated structure in which a polarizing film, a transparent protective film, a transparent support, and an optically anisotropic layer having a function of expanding a viewing angle are laminated in a specific angular relationship. Provides viewing angle expansion function. The laminated structure can be easily produced with high productivity by producing a polarizing film by a specific oblique stretching method. In particular, the conventional oblique stretching method has a problem that wrinkles and wrinkles occur in the obtained polarizing film, but the oblique stretching method according to the present invention does not cause such a problem, and has excellent smooth polarization. A film can be obtained and a high cutting yield can be obtained. As a result, the polarizing plate integrated with the optical isomer layer for expanding the viewing angle while maintaining the mutual function can be produced with high productivity, which contributes to the improvement of the productivity of the liquid crystal display device.
[0021]
The stretching method is preferred as a polarizing film stretching method applied to the present invention, and an oblique orientation is obtained by stretching a polymer film. Even if the film is stretched diagonally, the stretched film is wrinkled and crushed by setting the volatile content ratio during stretching of the film, the shrinkage ratio when shrinking the film, and / or the elastic modulus of the film before stretching within a predetermined range. Does not occur, and an excellent smooth polarizing film can be obtained.
[0022]
The liquid crystal display device of the present invention is characterized in that the absorption axis of the polarizing film is neither parallel nor perpendicular to the slow axis of the transparent support. The angle between the absorption axis direction of the polarizing film and the slow axis of the transparent support (regardless of before or after cutting the polarizing film) is preferably 10 ° or more and less than 90 °, more preferably 20 ° to 70 °, More preferably, it is 40 ° -50 °, particularly preferably 43-47 °. Further, as described above, in the bonding relationship between the transparent protective film and the polarizing film, the polarizing plate of the present invention preferably has an angle between the slow axis of the transparent protective film and the absorption axis of the polarizing film of 10 ° to 90 °. Is 20 ° to 70 °, more preferably 40 ° to 50 °, and particularly preferably 43 to 47 °.
By making the overlapping of each member into such an angular relationship, a polarizing film prepared in a long shape is bonded to one or more members prepared in a long shape to obtain a long laminate. Through a process of cutting (punching) into a desired size, a single plate polarizing plate can be obtained with high yield. Furthermore, if it is the said angle relationship, it can manufacture with high productivity, maintaining the viewing angle expansion function of a polarizing plate.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the constituent members of the liquid crystal display device of the present invention will be sequentially described. First, the liquid crystal display device of the present invention and its arrangement will be described.
[0024]
I. Liquid crystal display
<Disposition of liquid crystal display device>
FIG. 1 is a schematic view showing an embodiment of the configuration of the liquid crystal display device of the present invention, and FIG. 2 is a configuration of a polarizing plate. In this embodiment, an example in which active driving is performed using a nematic liquid crystal having positive dielectric anisotropy as a field effect liquid crystal will be described.
The liquid crystal display device shown in FIG. 1 includes a liquid crystal cell (5A to 8A) and a pair of polarizing plates 1A and 19A disposed on both sides of the liquid crystal cell. Between the polarizing plate 1A or 19A and the liquid crystal cells 5A to 8A, the first optical anisotropic layer 3A and the second optical anisotropic layer 10A functioning as an optical compensation film are respectively disposed. The liquid crystal cells 5A to 8A are composed of an upper electrode substrate 5A, a lower electrode substrate 8A, and liquid crystal molecules 7A sandwiched between them, and the liquid crystal molecules 7A are subjected to a rubbing treatment applied to the opposing surfaces of the substrates 5A and 8A. The orientation direction is controlled by the directions 6A and 9A.
[0025]
As shown in FIG. 2, the polarizing plates 1A and 18A are composed of a transparent support (also used as a transparent protective film) 12A (first transparent support or second transparent support) and a transparent protective film 17A (first transparent protective film or The polarizing film 14A (the first polarizing film or the second polarizing film) is sandwiched between the second transparent protective films. The absorption axis 15A of the polarizing film 14A is neither parallel nor perpendicular to the slow axis 18A of the transparent support 17A. The angle 16A between the absorption axis 15A direction of the polarizing film 14A and the slow axis 18A of the transparent support 17A is preferably 10 ° or more and less than 90 °, more preferably 20 ° to 70 °, and still more preferably 40 ° to 50 °. Particularly preferred is 43 to 47 °. The angle formed between the slow axis 13A of the transparent protective film 12A and the absorption axis 15A of the polarizing film 14A is preferably 10 ° to 90 °, more preferably 20 ° to 70 °, and still more preferably 40 ° to 50 °. °, particularly preferably 43 to 47 °. Furthermore, the slow axis of the first transparent support with the liquid crystal cell sandwiched between it and the slow axis of the second transparent support must be orthogonal.
[0026]
Referring again to FIG. 1, the alignment directions 4A and 11A of the liquid crystal molecules constituting each of the optically anisotropic layers 3A and 10A are, for example, the surface of a transparent support (not shown in FIG. 1, 17A in FIG. 2). An alignment film (not shown) is formed on the alignment film, and the alignment film is subjected to a rubbing treatment so that it can be aligned in a desired direction. In FIG. 1, the alignment direction of the liquid crystal molecules is the same as the absorption axis of the polarizing film (in FIG. 1, the absorption axes 2A and 19A of the polarizing plates 1A and 18A are shown; 15A in FIG. 2).
[0027]
The liquid crystal display device of the present invention is not limited to the above configuration, and may include other members. For example, a color filter may be disposed between the liquid crystal cell and the polarizing film. The liquid crystal display device of the present invention is preferable as a transmissive liquid crystal display device. In such an embodiment, a backlight using a cold or hot cathode fluorescent tube, a light emitting diode, or an electroluminescent element as a light source can be disposed on the back surface. .
[0028]
Usually, the polarizing plate is composed of a pair of transparent protective films and a polarizing film sandwiched between the transparent protective films. Conventionally, an optical compensation film is further laminated on the polarizing plate of this configuration and incorporated in a liquid crystal display device. In this invention, it can replace with the conventional polarizing plate and can use the laminated body which integrated the transparent protective film, the polarizing film, the transparent protective film, and the optically anisotropic layer as a polarizing plate. Since the transparent support of the optical compensation film can function as a protective film on one side of the polarizing film, the transparent protective film, the polarizing film, the transparent support (also used as the transparent protective film) and the optically anisotropic layer are laminated in this order. The integrated polarizing plate is preferable in terms of thinning. In the liquid crystal display device, the transparent protective film, the polarizing film, the transparent support, and the optically anisotropic layer are laminated in this order from the outside of the device (the side far from the liquid crystal cell).
[0029]
The type of the liquid crystal display device of the present invention is not particularly limited, and includes any of image direct view type, image projection type, and light modulation type liquid crystal display devices. The present invention is effective for an active matrix liquid crystal display device using three-terminal or two-terminal semiconductor elements such as TFT and MIM. Of course, it is also effective in a passive matrix liquid crystal display device represented by STN type called time-division driving.
[0030]
<Liquid crystal cell>
The liquid crystal cell is preferably OCB mode or TN mode. The TN mode is used in a wide range of applications from small liquid crystal display devices such as watches and calculators to notebook computers and large-screen liquid crystal televisions. Excellent productivity, especially in normally white mode, the contrast is very high. The OCB mode liquid crystal cell is a bend alignment mode liquid crystal cell in which rod-like liquid crystalline molecules are aligned in a substantially opposite direction (symmetrically) between the upper part and the lower part of the liquid crystal cell. A liquid crystal display device using this is disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, a liquid crystal mode using this is also called an OCB (Optically Compensatory Bend) liquid crystal mode. The bend alignment mode liquid crystal display device has an advantage of high response speed.
[0031]
Next, a TN mode liquid crystal cell will be described in detail below.
The twist direction and twist angle of the liquid crystal molecules 7A shown in FIG. 1 depend on the rubbing direction 6A of the upper electrode substrate 5A, the rubbing direction 9A of the lower electrode substrate 8A, and the type and amount of optically rotatory substance added to the nematic liquid crystal. It is prescribed. The twist angle is preferably about 90 degrees in consideration of the contrast ratio in the case of a notebook personal computer, a desktop personal computer monitor, and a liquid crystal display device for television use, and a liquid crystal display device for a portable terminal considering both the reflection mode and the transmission mode. Then, 30 to 80 degrees is preferable. Further, the tilt angle (pretilt angle) formed between the substrate interface and the liquid crystal molecules is preferably 2 ° or more in order to obtain alignment uniformity of the liquid crystal. By forming the polyimide alignment film on the substrate surface, it can be set to about 4 degrees.
[0032]
For example, in one example of the liquid crystal cell, a material having Δn = 0.075 (for example, manufactured by Merck) is used as the liquid crystal, the thickness of the liquid crystal layer is 4.9 μm, and Δnd is set to be 0.0 with visible light having a wavelength λ = 550 nm. It can be set to 367 μm. Generally, the range of brightness, contrast, and viewing angle of the display device varies depending on the size of Δnd of the liquid crystal cell. As Δnd increases, the brightness during white display increases and reaches a maximum at about 0.48 μm. However, since the display color changes from white to yellow, if set to 0.45 μm (visible light wavelength λ = 550 nm) or less. Good. Further, the smaller the Δnd is, the better the contrast and viewing angle are. However, when Δnd is 0.30 μm (visible light wavelength λ = 550 nm) or less, the white display becomes extremely dark, and therefore, it is set to be higher than that.
In addition, the crossing angle between the absorption axis (polarization axis) 19A of the lower polarizing plate and the absorption axis 12A of the upper polarizing plate is approximately 90 degrees, the twist angle of the liquid crystal layer is 90 degrees, and the absorption axis of the lower polarizing plate and the rubbing The angle with the direction (liquid crystal alignment direction) is preferably set to 90 degrees (may be 0 degrees).
[0033]
II. Polarizing film
The liquid crystal display device of the present invention includes two polarizing films that sandwich the liquid crystal cell, a first polarizing film, and a second polarizing film. Below, the polarizing film which can be used for this invention is explained in full detail focusing on the preferable extending | stretching method.
<Stretching method>
As the first and second polarizing films, it is preferable to use polarizing films prepared by obliquely stretching a polymer film. 3 and 4 show an example of an apparatus for obliquely stretching a polymer film for a polarizing film as a schematic plan view (hereinafter “polymer film for polarizing film” is confused / misunderstood with other polymer layers). Unless otherwise indicated, “polarizing film” is omitted).
In the present invention, the oblique stretching method preferably used is the step of introducing the original film shown in (a) in the direction of the arrow (A), the width direction drawing step shown in (b), and (c). It includes the step of sending the stretched film in the next step, that is, the (B) direction. Hereinafter, when referred to as “stretching step”, it refers to the entire step for carrying out the stretching method of the present invention, including these steps (a) to (c).
[0034]
The film is continuously introduced from the direction of (A) and is held for the first time at the B1 point by the holding means on the left side as viewed from the upstream side. At this time, one film end is not held and no tension is generated in the width direction. That is, the point B1 does not correspond to a substantial holding start point (hereinafter referred to as “substantial holding start point”) of the present invention.
The substantial holding start point is defined as the point at which both ends of the film are held for the first time. The substantial holding start point is the holding start point A1 on the downstream side and a straight line drawn substantially perpendicularly to the center line 11 (FIG. 3) or 21 (FIG. 4) of the introduction side film from A1 of the holding means on the opposite side. This is indicated by two points C1 that intersect the trajectory 13 (FIG. 3) or 23 (FIG. 4).
Starting from this point, if the holding means at both ends are conveyed at substantially constant speed, A1 moves to A2, A3... An for each unit time, and C1 similarly moves to C2, C3. That is, the straight line connecting the points An and Cn through which the holding means serving as a reference passes at the same point is the extending direction at that time.
[0035]
In the oblique stretching method, as shown in FIGS. 3 and 4, since An gradually lags behind Cn, the stretching direction is gradually inclined from the vertical in the transport direction. The substantial holding release point of the polymer film (hereinafter referred to as “substantial holding release point”) includes a Cx point that leaves the holding means upstream and a center line 12 of the film sent from Cx to the next process (FIG. 3). Alternatively, a straight line drawn substantially perpendicularly to 22 (FIG. 4) is defined by two points Ay that intersect the locus 14 (FIG. 3) or 24 (FIG. 4) of the holding means on the opposite side. The final film stretching direction angle is determined by the difference between the left and right holding means strokes Ay-Ax (ie, | L1-L2 |) at the end point (substantially holding release point) of the substantive drawing step, and the substantial holding releasing point. It is determined by the ratio of the distance W (the distance between Cx and Ay). Therefore, the inclination angle θ formed by the stretching direction with respect to the transport direction to the next process is
tan θ = W / (Ay−Ax), that is,
tan θ = W / | L1-L2 |
It is an angle satisfying.
The upper film edge in FIGS. 3 and 4 is held up to 18 (FIG. 3) or 28 (FIG. 4) after the Ay point, but the other end is not held, so a new width direction stretching does not occur. First, 18 and 28 are not the substantial holding release points of the present invention.
[0036]
As described above, in the oblique stretching method, the substantial holding start points at both ends of the film are not simple biting points into the left and right holding means. In the oblique stretching method, the two substantially holding start points are introduced into the process of holding the film by a straight line connecting either the left or right holding point and the other holding point, if more strictly described above. Defined as the point that is approximately perpendicular to the center line of the film being filmed and that these two holding points are located upstream. Similarly, in the oblique stretching method, the two substantially holding release points are such that the straight line connecting either the left or right holding point and the other holding point is substantially orthogonal to the center line of the film sent to the next process. And these two retention points are defined as being most downstream.
Here, “substantially orthogonal” means that the straight line connecting the center line of the film and the right and left substantial holding start points or substantial holding release points is 90 ± 0.5 °.
[0037]
When using a tenter type stretching machine to create a difference between the left and right strokes, due to mechanical restrictions such as the rail length, a large deviation often occurs between the biting point to the holding means and the substantial holding start point, or the holding means. There is a case where a large deviation occurs between the separation point from the actual holding point and the substantial retention release point. However, if the process between the substantial retention start point and the substantial retention release point defined above satisfies the relationship of the following formula (3), The goal is achieved.
| L2-L1 |> 0.4W (3)
[0038]
In the above, the inclination angle of the orientation axis in the stretched film obtained can be controlled and adjusted by the ratio of the exit width W of step (c) and the stroke difference | L1-L2 | between the two left and right substantial holding means. it can.
For polarizing plates and retardation films, films that are often oriented at 45 ° to the longitudinal direction are required. In this case, in order to obtain an orientation angle close to 45 °, it is preferable to satisfy the following formula (4):
0.9W <| L1-L2 | <1.1W (4)
More preferably, it is preferable to satisfy | fill following formula (5).
0.97W <| L1-L2 | <1.03W (5)
[0039]
As long as the concrete structure of the stretching step satisfies the above formula (3), the oblique stretching can be carried out by the stretching apparatus illustrated in FIGS. It can be designed arbitrarily in consideration of cost and productivity.
[0040]
The angle between the film introduction direction (b) in the stretching process and the film transport direction (b) in the next process can be any numerical value, but the total installation area of the equipment including the processes before and after stretching is minimized. From this viewpoint, this angle should be small, preferably within 3 °, and more preferably within 0.5 °. For example, this value can be achieved with the structure illustrated in FIGS. 3 and 6.
[0041]
Thus, in the method in which the film traveling direction does not substantially change, it is difficult to obtain an orientation angle of 45 ° with respect to the preferred longitudinal direction as a polarizing plate and retardation film only by increasing the width of the holding means. . Therefore, as shown in FIG. 3, | L1-L2 | can be increased by providing a step of once stretching and then contracting.
The stretching ratio is desirably 1.1 to 10.0 times, more desirably 2 to 10 times, and the subsequent shrinkage ratio is desirably 10% or more. Moreover, as shown in FIG. 6, it is also preferable to repeat the stretching-shrinking a plurality of times because | L1-L2 | can be increased.
[0042]
Further, from the viewpoint of minimizing the equipment cost of the stretching process, it is better that the number of bending times and the bending angle of the trajectory of the holding means are smaller. From this point of view, as illustrated in FIGS. 4, 5, and 7, the angle formed by the film traveling direction at the exit of the step of holding both ends of the film and the substantial stretching direction of the film is inclined by 20 to 70 °. It is preferable to bend the film traveling direction while holding both ends of the film.
[0043]
As a device that can be used in the oblique stretching method and stretches the polymer film while holding both ends of the polymer film while applying tension to the polymer film, a so-called tenter device as shown in FIGS. Further, in addition to the conventional two-dimensional tenter, a stretching process in which a path difference is provided between the gripping means at both ends spirally as shown in FIG. 8 can be used.
[0044]
In the case of a tenter-type stretching machine, there are many structures in which the chain with the clip fixed proceeds along the rail. However, when the stretching method is not equal to the left and right as in the present invention, the result is illustrated in FIGS. 3 and 4. As described above, the end of the rail may be shifted at the process entrance and exit, and the left and right sides may be bitten at the same time and may not be detached. In this case, the substantial process lengths L1 and L2 are not the distance between simple engagement and disengagement as described above, but the process of the portion where the holding means holds the both ends of the film as described above. It is long.
[0045]
If there is a difference in the traveling speed between the left and right sides of the film at the stretching process exit, wrinkles and deviations occur at the stretching process exit, and therefore the transport speed difference between the left and right film gripping means is required to be substantially the same speed. The speed difference is preferably 1% or less, more preferably less than 0.5%, and most preferably less than 0.05%. The speed described here is the length of the trajectory traveled by the left and right holding means per minute. In general tenter drawing machines, etc., there are speed irregularities that occur in the order of seconds or less depending on the period of the sprocket teeth that drive the chain, the frequency of the drive motor, etc. It does not correspond to the speed difference described in the book.
[0046]
<Shrinkage>
Shrinkage of the stretched polymer film may be performed in any step during stretching or after stretching. The shrinkage may be achieved by eliminating the wrinkles of the polymer film that occurs when orienting in an oblique direction. Examples of means for shrinking the film include a method of removing volatiles by applying a temperature. Any means may be used as long as it is contracted. As a preferable shrinkage rate of the film, it is preferable to shrink by 10% or more as a value by shrinking by 1 / sin θ times or more using the orientation angle θ with respect to the longitudinal direction.
[0047]
<Volatile content>
Further, as the left and right stroke difference occurs, wrinkles and shifts occur in the film. In order to solve this problem, it is preferable that the support of the polymer film is maintained and the volatile content in the polymer film is stretched in a state of 10% or more and then contracted to reduce the volatile content. In the present specification, the “volatile fraction” represents the volume of volatile components contained per unit volume of the film, and is a value obtained by dividing the volatile component volume by the film volume. Examples of the method for containing volatile components include casting a film and containing solvent and water, dipping, applying and spraying in solvent and water before stretching, and applying solvent and water during stretching. . Since hydrophilic polymer films such as polyvinyl alcohol contain water in a high-temperature and high-humidity atmosphere, they can contain volatile components by stretching after conditioning in a high-humidity atmosphere or by stretching under high-humidity conditions. . Other than these methods, any means may be used as long as the volatile content of the polymer film can be increased to 5% or more.
[0048]
The preferred volatile content varies depending on the type of polymer film. The maximum volatile content is possible as long as the support of the polymer film is maintained. In polyvinyl alcohol, 10% to 100% is preferable as the volatile content rate. In cellulose acylate, 10% to 200% is preferable.
[0049]
<Elastic modulus>
As the physical properties of the polymer film before stretching, if the elastic modulus is too low, the shrinkage rate during stretching and after stretching becomes low, and wrinkles are difficult to disappear. On the other hand, if it is too high, the tension applied at the time of stretching will increase, and it will be necessary to increase the strength of the portions that hold both ends of the film, increasing the load on the machine. Therefore, the elastic modulus of the polymer film before stretching is preferably 0.1 MPa or more and 500 MPa or less, more preferably 0.1 MPa or more and 500 MPa or less in terms of Young's modulus.
[0050]
<Distance from wrinkle occurrence to disappearance>
The wrinkles of the polymer film that occur when orienting in an oblique direction may be eliminated by the substantial retention release point. However, if it takes a long time from the generation of wrinkles to the disappearance, the stretching direction may vary. Therefore, it is preferable that the wrinkles disappear at a transition distance as short as possible from the point where the wrinkles occur. For this purpose, there is a method of increasing the volatilization rate of the volatile content.
[0051]
<Foreign matter>
Since the surface will become rough when the foreign material has adhered to the polymer film before extending | stretching, it is preferable to remove a foreign material. If foreign matter is present, color unevenness and optical unevenness are caused, particularly during the production of a polarizing plate. In addition, it is important that no foreign matter adheres before the protective film is bonded, and it is preferable to manufacture in an environment with as little dust as possible floating. In this specification, the “amount of foreign matter” is a value obtained by dividing the mass of the foreign matter attached to the film surface by the surface area, and represents the number of grams per square meter. The foreign matter is preferably 1% by mass or less, more preferably 0.5% by mass or less, and the smaller the better. The method for removing the foreign matter is not particularly limited, and any method may be used as long as the foreign matter can be removed without adversely affecting the polymer film before stretching. For example, there are a method of scraping off foreign matter by spraying a water flow, a method of scraping off foreign matter by gas jetting, a method of scraping off foreign matter using a blade such as cloth or rubber.
[0052]
<Dry>
As long as the generated wrinkles disappear, the drying conditions may be any. However, preferably, after the desired orientation angle is obtained, the drying point may be adjusted with the shortest possible moving distance. The drying point means a place where the surface film temperature of the film becomes the same as the ambient temperature. For this reason, it is preferable that the drying speed is as fast as possible.
[0053]
<Drying temperature>
As long as the generated wrinkles disappear, the drying temperature condition may be arbitrary, but varies depending on the stretched film. When producing a polarizing film using a polyvinyl alcohol-type film, 20 to 100 degreeC is preferable, More preferably, it is 40 to 90 degreeC.
[0054]
<Swelling rate>
When the polymer film is a polyvinyl alcohol film and contains a hardener, the swelling ratio with respect to water before and after stretching is preferably different in order to keep the stretched state in an oblique direction without relaxation. Specifically, it is preferable that the swelling ratio before stretching is high and the swelling ratio after stretching and drying is low. More preferably, the swelling ratio with respect to water before stretching is 3% or more, and the swelling ratio after drying is 3% or less.
[0055]
<Definition of refraction part>
In the oblique stretching method, a large bending rate is often required for the rail that regulates the trajectory of the holding means. In order to avoid interference between film gripping means due to sudden bending or local stress concentration, it is desirable that the trajectory of the gripping means draws an arc at the bent portion.
[0056]
<Stretching speed>
In the oblique stretching method, the polymer film is stretched at a speed of 1.1 times / minute or more, preferably 2 times / minute or more, and faster, when expressed in terms of a draw ratio per unit time. Further, the traveling speed in the longitudinal direction is 0.1 m / min or more, preferably 1 m / min or more, and a higher speed is preferable from the viewpoint of productivity. In either case, the upper limit varies depending on the film to be stretched and the stretching machine.
[0057]
<Longitudinal tension>
In the oblique stretching method, when the both ends of the film are held by the holding means, it is preferable to keep the film stretched so as to be easily held. Specifically, a method such as stretching a film by applying tension in the longitudinal direction can be mentioned. The tension varies depending on the state of the film before stretching, but it is preferable that the tension is not loosened.
[0058]
<Temperature temperature>
In the oblique stretching method, the environmental temperature during film stretching may be at least the freezing point of volatile components contained in the film. When the film is polyvinyl alcohol, it is preferably 25 ° C. or higher. Moreover, when extending | stretching the polyvinyl alcohol which immersed the iodine and boric acid for producing a polarizing film, 25 to 90 degreeC is preferable.
[0059]
<Humidity during stretching>
When a film having a volatile content of water, such as polyvinyl alcohol or cellulose acylate, is stretched, it may be stretched in a humidity-controlled atmosphere. In the case of polyvinyl alcohol, it is preferably 50% or more, preferably 80% or more, more preferably 90% or more.
[0060]
<Stretched film>
There is no restriction | limiting in particular regarding the polymer film made into the object of extending | stretching, The film which consists of an appropriate thermoplastic polymer can be used. Examples of the polymer include polyvinyl alcohol (PVA), polycarbonate, cellulose acylate, polysulfone and the like.
[0061]
In particular, the thickness of the film before stretching is preferably 1 μm to 1 mm, more preferably 20 to 300 μm, and particularly preferably 75 to 200 μm from the viewpoint of film holding stability and stretching uniformity. The thickness of the film after stretching and drying is preferably 3 μm to 50 μm, more preferably 5 μm to 40 μm, and particularly preferably 10 μm to 30 μm.
[0062]
PVA is preferably used as the polymer for the polarizing film film. PVA is usually a saponified polyvinyl acetate, but may contain components copolymerizable with vinyl acetate, such as unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, and vinyl ethers. . In addition, modified PVA containing an acetoacetyl group, a sulfonic acid group, a carboxyl group, an oxyalkylene group, or the like can also be used.
[0063]
The saponification degree of PVA is not particularly limited, but is preferably 80 to 100 mol%, particularly preferably 90 to 100 mol% from the viewpoint of solubility and the like. The degree of polymerization of PVA is not particularly limited, but is preferably 1000 to 10,000, and particularly preferably 1500 to 5000.
[0064]
<Dyeing prescription and method>
Although a polarizing film is obtained by dyeing PVA, the dyeing process is performed by gas phase or liquid phase adsorption. As an example in the case of performing in a liquid phase, when iodine is used, it is performed by immersing a PVA film in an iodine-potassium iodide aqueous solution. Iodine is preferably 0.1 to 20 g / l, potassium iodide is preferably 1 to 200 g / l, and the mass ratio of iodine and potassium iodide is preferably 1 to 200. The dyeing time is preferably 10 to 5000 seconds, and the liquid temperature is preferably 5 to 60 ° C. As a dyeing method, not only immersion but any means such as application or spraying of iodine or a dye solution can be used. The dyeing step may be performed at any timing before or after the oblique stretching step, but it is particularly preferable to dye in the liquid phase before the stretching step because the film is appropriately swelled to facilitate stretching.
[0065]
<Hardener and metal salt addition>
In the process of producing a polarizing film by stretching PVA, it is preferable to use an additive that crosslinks PVA. In particular, when the oblique stretching method of the present invention is used, if the PVA is not sufficiently hardened at the exit of the stretching process, the orientation direction of the PVA may shift due to the tension of the process. It is preferable to immerse in or apply a solution to the crosslinking agent solution to contain the crosslinking agent. The means for applying the cross-linking agent to the PVA film is not particularly limited, and any method such as dipping, coating and spraying of the film into the liquid can be used, but the dipping method and the coating method are particularly preferable. As a coating means, any generally known means such as a roll coater, a die coater, a bar coater, a slide coater, and a curtain coater can be used. Also preferred is a system in which a cloth impregnated with a solution, cotton, a porous material or the like is brought into contact with the film. As the crosslinking agent, those described in US Pat. No. 2,328,977 can be used, but boric acid and borax are preferably used practically. In addition, metal salts such as zinc, cobalt, zirconium, iron, nickel, and manganese can be used together.
Moreover, you may provide a washing | cleaning / water washing process after adding a hardening agent.
[0066]
The application of the cross-linking agent may be performed before biting into the stretching machine, or may be performed after biting, and in the step (b) in the example of FIGS. 3 and 4 where the stretching in the width direction is substantially finished. What is necessary is just to carry out in any process to the termination.
[0067]
<Polarizer>
It is also preferable to dye with a dichroic dye in addition to iodine. Specific examples of dichroic dyes include, for example, dye compounds such as azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes and anthraquinone dyes. I can give you. A water-soluble one is preferred, but not limited thereto. Further, it is preferable that a hydrophilic substituent such as a sulfonic acid group, an amino group or a hydroxyl group is introduced into these dichroic molecules. Specific examples of the dichroic molecule include C.I. Ai. direct. Yellow 12, sea. Ai. direct. Orange 39, sea. Ai. direct. Orange 72, sea. Ai. direct. Red 39, Sea. Ai. direct. Red 79, Sea. Ai. direct. Red 81, Sea. Ai. direct. Red 83, Sea. Ai. direct. Red 89, Sea. Ai. direct. Violet 48, C.I. Ai. direct. Blue 67, Sea. Ai. direct. Blue 90, Sea. Ai. direct. Green 59, Sea. Ai. Acid. Red 37 and the like, and further, JP-A-62-70802, JP-A-1-161202, JP-A-1-172906, JP-A-1-172907, JP-A-1-183602, JP-A-1-248105. And dyes described in JP-A-1-265205 and JP-A-7-261024. These dichroic molecules are used as free acids or alkali metal salts, ammonium salts, and salts of amines. By blending two or more of these dichroic molecules, it is possible to produce polarizers having various hues. As a polarizing element or polarizing plate, a compound (pigment) that exhibits black when the polarization axes are orthogonal to each other and a compound in which various dichroic molecules are blended so as to exhibit black are excellent in terms of both single-plate transmittance and polarization rate.
[0068]
The stretching method of the present invention can also be preferably used for the production of a so-called polyvinylene polarizing film in which a polyene structure is formed by dehydrating and dechlorinating PVA and polyvinyl chloride, and polarized light is obtained by a conjugated double bond.
[0069]
III. Transparent protective film
The liquid crystal display device of the present invention includes first and second transparent protective films. The first and second transparent protective films are used by being attached to at least one surface of the first and second polarizing films, respectively. The kind of transparent protective film is not specifically limited, Films, such as cellulose esters, such as a cellulose acetate, a cellulose acetate butyrate, a cellulose propionate, a polycarbonate, polyolefin, a polystyrene, polyester, can be used.
[0070]
The transparent protective film is usually supplied in a roll form, and it is preferable that the transparent protective film is continuously bonded to the long polarizing film so that the longitudinal directions thereof coincide with each other. Here, the orientation axis (slow axis) of the transparent protective film may be any direction, and the orientation axis of the transparent protective film is preferably parallel to the longitudinal direction for ease of operation.
[0071]
Further, the angle between the slow axis (orientation axis) of the transparent protective film and the absorption axis (stretching axis) of the polarizing film is not particularly limited, and can be appropriately set according to the purpose. When a transparent protective film whose alignment axis is parallel to the longitudinal direction is bonded to a polarizing film whose absorption axis obtained by oblique stretching is not parallel to the longitudinal direction, the absorption axis of the polarizing film and the alignment axis of the transparent protective film are A non-parallel polarizing plate is obtained. A polarizing plate in which the absorption axis of the polarizing film and the orientation axis of the transparent protective film are bonded at an angle that is not parallel has an effect that the dimensional stability is excellent. This performance is particularly exerted when used in a liquid crystal display device. In particular, when the inclination angle between the slow axis of the transparent protective film and the absorption axis of the polarizing film is 10 ° or more and 90 ° or less, the dimensional stability effect is effectively exhibited, which is preferable.
[0072]
In general, the retardation of the transparent protective film is preferably low. However, when the absorption axis of the polarizing film and the orientation axis of the transparent protective film are not parallel, the polarizing value is particularly large when the retardation value of the transparent protective film is a certain value or more. Since the axis and the orientation axis (slow axis) of the transparent protective film are obliquely shifted, the linearly polarized light changes to elliptically polarized light, which is not preferable. Accordingly, the retardation of the transparent protective film is, for example, preferably 10 nm or less at 632.8 nm, and more preferably 5 nm or less. From the viewpoint of such low retardation, polyolefins such as cellulose triacetate, ZEONEX, ZEONOR (both manufactured by Nippon Zeon Co., Ltd.) and ARTON (manufactured by JSR Co., Ltd.) are preferably used as the transparent protective film. It is done. Other examples include non-birefringent optical resin materials as described in JP-A-8-110402 or JP-A-11-293116.
[0073]
<Adhesive>
The adhesive between the polarizing film and the protective film is not particularly limited, and examples thereof include PVA resin (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) and boron compound aqueous solution. PVA resin is preferable. The thickness of the adhesive layer is preferably 0.01 to 10 μm after drying, and particularly preferably 0.05 to 5 μm.
[0074]
<Integrated manufacturing process of polarizing film and transparent protective film>
As described above, the polarizing film is preferably prepared through a drying step in which the polymer film for polarizing film is obliquely stretched and then contracted to reduce the volatile content, but the transparent protective film is formed on at least one side after drying or during drying. It is preferable to integrate the constituent members by attaching a transparent protective film on one side or a transparent support having an optically anisotropic layer on the opposite side and then applying a post-heating step. . As a specific attaching method, during the film drying process, the transparent protective film is attached to the polarizing film using an adhesive while holding both ends, and then both ends are cut off, or after drying, from both end holding parts There is a method of releasing the polarizing film, cutting off both ends of the film, and then attaching a transparent protective film. As a method for cutting off the ears, general techniques such as a method of cutting with a cutter such as a blade or a method of using a laser can be used. After bonding, it is preferable to heat in order to dry the adhesive and improve the polarization performance. The heating condition varies depending on the adhesive, but in the case of an aqueous system, it is preferably 30 ° C. or higher, more preferably 40 ° C. or higher and 100 ° C. or lower, and further preferably 50 ° C. or higher and 90 ° C. or lower. It is more preferable in terms of performance and production efficiency that these processes are manufactured in a consistent line.
[0075]
<Punching>
FIG. 10 shows an example of punching a long laminate composed of the polarizing film and the transparent protective film integrated as described above, together with an example of punching the conventional polarizing plate of FIG. As shown in FIG. 9, the conventional polarizing plate has an absorption axis 71 of polarized light, that is, the stretching axis coincides with the longitudinal direction 72, whereas the polarizing plate of the present invention is polarized as shown in FIG. The absorption axis 81 of the liquid crystal, that is, the stretching axis is inclined by 45 ° with respect to the longitudinal direction 82, and this angle is between the absorption axis of the polarizing plate when bonded to the liquid crystal cell in the LCD and the vertical or horizontal direction of the liquid crystal cell itself. Since it corresponds to the angle formed, oblique punching is not required in the punching process. Moreover, as can be seen from FIG. 10, since the polarizing film produced by the oblique stretching method can be cut straight along the longitudinal direction, it can be manufactured by slitting along the longitudinal direction without punching. Therefore, productivity is remarkably excellent.
As described above, the punching may be performed at this stage or after the transparent support having the transparent protective film, the polarizing film, and the optically anisotropic layer is overlaid.
[0076]
<Performance of the produced polarizing plate>
The optical properties and durability (short-term and long-term storage stability) of a polarizing plate comprising a transparent protective film, a polarizer and a transparent support related to the present invention are commercially available super high contrast products (for example, Sanlitz Co., Ltd.). It is preferable to have a performance equivalent to or higher than that of HLC2-5618, manufactured by HLC. Specifically, the visible light transmittance is 42.5% or more and the degree of polarization {(Tp−Tc) / (Tp + Tc)} ^1/2 ≧ 0.9995 (where Tp is parallel transmittance, Tc is orthogonal transmittance), before and after standing at 60 ° C., humidity 90% RH atmosphere for 500 hours and 80 ° C., dry atmosphere for 500 hours It is preferable that the change rate of the light transmittance is 3% or less, more preferably 1% or less based on the absolute value, and the change rate of the polarization degree is 1% or less, more preferably 0.1% or less based on the absolute value. .
[0077]
IV. Transparent support
The liquid crystal display device of the present invention includes two transparent supports that sandwich the liquid crystal cell, a first transparent support, and a second transparent support. A first optically anisotropic layer is provided on the first transparent support, and a second optically anisotropic layer is provided on the second transparent support.
The Re (retardation) represented by the following formula (1) of the transparent support that can be used in the present invention is preferably low. When the absorption axis of the polarizing film and the slow axis of the transparent support are not parallel, the polarizing axis and the slow axis of the transparent support are obliquely shifted, especially when the retardation value of the transparent support is a certain value or more. Therefore, linearly polarized light changes to elliptically polarized light, which is not preferable. Therefore, the retardation of the transparent support is, for example, preferably 10 nm or less at 632.8 nm, and more preferably -5 nm or more and 5 nm or less. The in-plane variation in Re of the transparent support is preferably ± 3 nm or less, more preferably ± 2 nm or less, and particularly preferably ± 1 nm or less. Furthermore, the Re (retardation) value of 400 nm to 700 nm is preferably ± 2 nm or less, more preferably ± 1 nm or less, particularly preferably ± 0.5 nm or less with respect to the Re average value of 400 nm to 700 nm.
Re value = (nx−ny) × d (1)
[0078]
From the viewpoint of such low retardation, polyolefins such as cellulose triacetate, ZEONEX, ZEONOR (both manufactured by Nippon Zeon Co., Ltd.) and ARTON (manufactured by JSR Co., Ltd.) are preferably used as the transparent support. It is done.
[0079]
From the viewpoint of optical compensation, Rth represented by the following formula (2) is preferably 25 nm or more and 300 nm or less, and more preferably 50 nm or more and 200 nm or less. The in-plane variation of Rth of the transparent support is preferably ± 5 nm or less, more preferably ± 3 nm or less. Further, the Rth value of 400 nm to 700 nm is preferably ± 3 nm or less, more preferably ± 2 nm or less, particularly preferably ± 1 nm or less with respect to the Rth average value of 400 nm to 700 nm.
Rth value = {(nx + ny) / 2−nz} × d (2)
[0080]
In order to adjust the retardation of the polymer film, a method of applying an external force such as stretching is generally used, but an aromatic compound having at least two aromatic rings as described in the specification of European Patent 0911656A2 is used. It can also be used as a foundation raising agent. When the polymer film is cellulose triacetate, the aromatic compound is in the range of 0.01 to 20 parts by mass, more preferably in the range of 0.05 to 15 parts by mass, particularly 0.1 to 10 parts by mass, relative to 100 parts by mass of cellulose triacetate. It is preferable to use within the range of parts. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound is preferably an aromatic hydrocarbon ring or an aromatic heterocycle, particularly preferably a 1,3,5-triazine ring.
[0081]
In order to realize Re and Rth of the transparent support of the present invention with a predetermined thickness and small variations, it is preferable to use cellulose acylate in which the type of acyl group and the degree of substitution are defined. Below, the cellulose acylate preferably used for this invention is demonstrated in detail.
[0082]
If the total acyl substitution degree of the cellulose acylate is too low, there is a problem that Re tends to be larger than a desired value due to the conveyance tension at the time of casting, and in-plane variation is likely to occur. Further, the substitution degree of the acyl group at the 6-position is preferably 0.9 or more. When the degree of substitution is 0.9 or less, variations in Re and Rth tend to occur.
As the raw material cotton of cellulose acetate that is preferably used as the transparent support of the present invention, known raw materials described in the Japanese Society for Invention and Innovation Technique 2001-1745 can be used. Cellulose acylate can also be synthesized by a known method described in Umeda et al., Wood Chemistry 180-190 (Kyoritsu Shuppan, 1968).
[0083]
In the present invention, it is preferable to use a cellulose acylate film produced by a solvent casting method as a transparent support. The film can be produced using a cellulose acylate dope. The organic solvent used is not particularly limited, but a mixture of a chlorinated solvent, alcohols, ketones and esters is preferably used. These esters and ketones may have a cyclic structure or may have two or more types of functional groups.
[0084]
Examples of esters include methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate and the like. Of these, methyl acetate is particularly preferred. Examples of ketones include acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone and the like. Of these, acetone, cyclopentanone, and cyclohexanone are particularly preferable.
[0085]
From the viewpoint of reducing variations in Re and Rth, the concentration of the solution is preferably 20 to 30% by weight, and preferably 20 to 26% by weight.
[0086]
By the way, from the viewpoint of the global environment and working environment, the organic solvent is preferably one that does not substantially contain a chlorinated solvent. “Substantially free” means that the proportion of the chlorinated solvent in the organic solvent is less than 10% by mass, preferably less than 5% by mass, more preferably less than 3% by mass. Further, it is preferable that no chlorine-based solvent such as methylene chloride is detected from the produced cellulose acylate film.
[0087]
Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol and cyclohexanol, 2-fluoroethanol, 2,2,2-trifluoroethanol, and the like. Of these, methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol are particularly preferable.
[0088]
In preparing the cellulose acylate solution, first, the cellulose acylate is added while stirring the solvent in the tank at room temperature, and the cellulose acylate is swollen with the solvent. The swelling time is preferably 10 minutes or more, and less than 10 minutes is undesirable because insoluble matter remains. Moreover, in order to fully swell cellulose acylate, the temperature of the solvent is preferably 0 to 40 ° C. If the temperature is lower than 0 ° C, the swelling rate tends to decrease and insoluble matter tends to remain. If the temperature is higher than 40 ° C, the swelling rapidly occurs, so that the central portion tends not to swell sufficiently. In order to dissolve the cellulose acylate in the solvent after the swelling step, it is preferable to use either the cooling dissolution method, the high temperature dissolution method, or both. As a specific method relating to the cooling dissolution method and the high temperature dissolution method, a known method described in JIII Journal of Technology 2001-1745 can be used.
[0089]
If desired, the cellulose acylate dope obtained by the above method may be dissolved at a low concentration and then concentrated to an optimal concentration by using a concentrating means in order to further facilitate dissolution.
[0090]
Prior to casting, it is preferable to filter off foreign matters such as undissolved matter, dust, and impurities using a suitable filter medium such as a wire mesh, paper, or flannel. A method is not specifically limited, The well-known method as described in Invention Association open technical report 2001-1745 grade etc. can be mentioned.
[0091]
Various additives can be added to the cellulose acylate solution depending on the application in each preparation step. These additives include plasticizers, UV inhibitors and degradation inhibitors (eg, antioxidants, peroxide decomposers, radical inhibitors, metal deactivators, acid scavengers, amines), and release agents. , Fine particles and the like.
[0092]
Next, a method for producing a film (transparent support) using the cellulose acylate solution preferably used in the present invention will be described.
As a method and equipment for producing a cellulose acylate film that can be used as a transparent support, conventionally, a solution casting film forming method and a solution casting film forming apparatus used for producing a cellulose triacetate film can be used. The dope (cellulose acylate solution) prepared from the dissolution tank (kettle) is temporarily stored in a stock tank, and the foam contained in the dope is defoamed and finally prepared. The dope is sent from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations, and the dope is run endlessly from the die (slit) of the pressure die. The dope film (also referred to as web) is peeled off from the metal support at a peeling point that is uniformly cast on the metal support, and the metal support has substantially gone around. Both ends of the obtained web are sandwiched between clips, transported by a tenter while maintaining the width, dried, and then transported by a roll group of a drying device, dried, and wound up to a predetermined length by a winder. The combination of the tenter and the roll group dryer varies depending on the purpose. In the solution casting film forming method used for silver halide photographic light-sensitive materials and functional protective films for electronic displays, in addition to the solution casting film forming apparatus, an undercoat layer, an antistatic layer, an antihalation layer, a protective layer, etc. In many cases, a coating device is added to the surface processing of the film.
[0093]
In order to reduce variations in film thickness and reduce variations in retardation, a cellulose acylate solution can be used as a single layer or a plurality of cellulose acylate solutions on a smooth band or drum as a metal support. May be co-cast. For example, when casting a plurality of cellulose acylate solutions, a film is formed while casting and laminating a solution containing cellulose acylate from a plurality of casting ports provided at intervals in the traveling direction of the metal support. A known method described in JP-A-11-198285 can be applied. Moreover, the method of forming into a film by casting a cellulose acylate solution from two casting openings may be used. Alternatively, a cellulose acylate film casting method may be used in which a flow of a high-viscosity cellulose acylate solution is wrapped with a low-viscosity cellulose acylate solution, and the high-low viscosity cellulose acylate solution is simultaneously extruded. By carrying out such co-casting, since the smoothing in the drying of the surface proceeds as described above, a significant improvement in the surface shape can be expected. In the case of co-casting, the thickness of each layer is not particularly limited, but preferably the outer layer is preferably thinner than the inner layer. In this case, the thickness of the outer layer is preferably 1 to 30 μm, and more preferably 1 to 20 μm. Here, the outer layer refers to a surface that is not a band surface (drum surface) in the case of two layers, and layers on both surface sides of the completed film in the case of three or more layers. The inner layer indicates a band surface (drum surface) in the case of two layers, and indicates a layer inside the outer layer in the case of three or more layers.
Furthermore, when producing a transparent support having another functional layer, the cellulose acylate solution is mixed with another functional layer (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer). It can also be cast simultaneously with the forming solution.
[0094]
30-250 degreeC is preferable and, as for the drying temperature at the time of drying the said cellulose acylate dope on a metal support body, 40-180 degreeC is more preferable.
[0095]
The thickness of the produced cellulose acylate film (after drying) is preferably 20 to 150 μm, and more preferably 20 to 100 μm. What is necessary is just to adjust the solid content concentration contained in dope, the slit gap | interval of die die, the extrusion pressure from die | dye, a metal support body speed | rate etc. so that a film may become desired thickness.
[0096]
Here, if desired, surface treatment of the cellulose acylate film can improve adhesion between the cellulose acylate film and each functional layer (for example, the undercoat layer and the back layer). Depending on the application, it is preferable to provide an antistatic layer or a hydrophilic binder layer for adhering to the polarizing film on at least one layer of the cellulose acylate film.
[0097]
<Surface treatment of transparent support>
The transparent support used in the present invention is preferably subjected to a surface treatment. Examples of the surface treatment include saponification treatment, plasma treatment, flame treatment, and ultraviolet irradiation treatment. Saponification treatment includes acid saponification treatment and alkali saponification treatment. The plasma treatment includes corona discharge treatment and glow discharge treatment. In order to maintain the flatness of the film, in these surface treatments, it is preferable that the temperature of the polymer film is equal to or lower than the glass transition temperature (Tg). When using as a transparent protective film of a polarizing plate, it is particularly preferable to carry out an acid saponification treatment or an alkali saponification treatment from the viewpoint of adhesiveness with the polarizing film.
[0098]
Hereinafter, the example which performs an alkali saponification process is demonstrated concretely. The alkali saponification treatment is preferably performed in a cycle in which the polymer film is immersed in an alkali solution, neutralized with an acidic solution, washed with water and dried. Examples of the alkaline solution include potassium hydroxide solution and sodium hydroxide solution. The prescribed concentration of hydroxide ions in the alkaline solution is preferably in the range of 0.1N to 3.0N, more preferably in the range of 0.5N to 2.0N. The temperature of the alkaline solution is preferably in the range of 0 to 90 ° C, and more preferably in the range of 40 to 70 ° C.
[0099]
The surface energy after saponification is preferably 55 mN / m, more preferably 60 mN / m to 75 mN / m. The surface energy of the solid can be determined by the contact angle method, the wet heat method, and the adsorption method described in “Basics and Applications of Wetting” (Realize, 1989.12.10). In the case of a cellulose acetate film, the contact angle method is preferably used.
Specifically, two kinds of solutions having known surface energies are dropped onto a cellulose acetate film, and at the intersection between the surface of the droplet and the surface of the film, at the angle formed by the tangent line drawn on the droplet and the surface of the film, The surface angle of the film can be calculated by defining the angle containing the droplet as the contact angle.
[0100]
V. Optically anisotropic layer
<Optically anisotropic layer made of liquid crystalline compound>
The liquid crystal display device of the present invention includes two optically anisotropic layers, a first optically anisotropic layer, and a second optically anisotropic layer that sandwich a liquid crystal cell. Each of the first and second optically anisotropic layers may be a single layer or a plurality of layers. The first and second optically anisotropic layers are preferably formed on alignment films formed on the first and second transparent supports, respectively.
[0101]
The liquid crystalline compound used for the optically anisotropic layer is preferably a discotic compound. Examples of discotic compounds include C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, page 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), azacrown type, phenylacetylene type macrocycle, etc. can be mentioned. The above discotic (discotic) compounds generally have a structure in which these are used as a mother nucleus at the center of a molecule, and a linear alkyl group, an alkoxy group, a substituted benzoyloxy group, etc. are radially substituted as the linear chain. , Which shows liquid crystallinity and is generally called a discotic liquid crystal. However, the molecule itself is not limited to the above description as long as the molecule itself has negative uniaxiality and can give a certain orientation. In the present specification, the term “formed from a discotic compound” does not require that the final product is the compound, for example, a group in which the low-molecular discotic liquid crystal reacts with heat, light, or the like. As a result, it may be polymerized or cross-linked by reaction with heat, light or the like, resulting in high molecular weight and loss of liquid crystallinity. Preferred examples of the discotic compound are described in JP-A-8-50206.
[0102]
The optically anisotropic layer is preferably a layer made of a compound having a discotic structural unit. The surface of the discotic structural unit is inclined with respect to the transparent support surface, and the angle formed by the surface of the discotic structural unit and the transparent support surface is changed in the depth direction of the optically anisotropic layer. Is preferred. The angle (tilt angle) of the surface of the discotic structural unit generally increases or decreases with increasing distance from the bottom surface of the optically anisotropic layer in the thickness direction of the optically anisotropic layer. It is preferable that the tilt angle increases as the distance from the bottom surface of the optically anisotropic layer increases. In addition, changes in tilt angle include continuous increase, continuous decrease, linear increase, nonlinear increase, intermittent increase, intermittent decrease, changes including continuous increase and continuous decrease, and increase and decrease. An intermittent change etc. can be mentioned. The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if the inclination angle includes a region that does not change, it is preferable that the inclination angle increases or decreases as a whole. Further, it is preferable that the inclination angle increases as a whole, and it is particularly preferable that the inclination angle changes continuously.
[0103]
The optically anisotropic layer is generally formed by applying a solution obtained by dissolving a discotic compound and other compounds in a solvent onto an alignment film, drying it, and then heating it to a discotic nematic phase formation temperature, and then aligning it (discotic It is obtained by maintaining the nematic phase and cooling. Alternatively, the optically anisotropic layer is formed by applying a solution obtained by dissolving a discotic compound and another compound (for example, a polymerizable monomer, a photopolymerization initiator) in a solvent onto the alignment film, drying, and then discotic It is obtained by heating to the nematic phase formation temperature, polymerizing (by irradiation with UV light or the like), 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 in the range of 70 to 300 ° C, particularly preferably in the range of 70 to 170 ° C.
[0104]
Further, the inclination angle of the discotic unit on the support side can be generally adjusted by selecting a discotic compound or a material for the alignment film, or by selecting a rubbing treatment method. Further, the inclination angle of the discotic unit on the surface side (air side) can be generally adjusted by selecting a discotic compound or another compound used together with the discotic compound. Examples of other compounds used with the discotic compound include plasticizers, surfactants, polymerizable monomers and polymers. Further, the degree of change in the tilt angle can be adjusted by making the same selection as described above.
[0105]
The plasticizer, surfactant and polymerizable monomer used together with the discotic compound are compatible with the discotic compound as long as they can change the tilt angle of the liquid crystalline discotic compound or do not inhibit the alignment. Any compound can be used. Among these, polymerizable monomers (eg, compounds having a vinyl group, a vinyloxy group, an acryloyl group, and a methacryloyl group) are preferable. It is preferable to add the said compound generally in 1-50 mass% with respect to a discotic compound, and it is more preferable to add in 5-30 mass%.
[0106]
As the polymer used together with the discotic compound, any polymer can be used as long as it is compatible with the discotic compound and can change the tilt angle of the liquid crystalline discotic compound. Examples of polymers include cellulose esters. Preferable examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, hydroxypropyl cellulose and cellulose acetate butyrate. The polymer is generally added in the range of 0.1 to 10% by mass with respect to the discotic compound so as not to inhibit the alignment of the liquid crystalline discotic compound. This addition amount is preferably in the range of 0.1 to 8% by mass, and more preferably in the range of 0.1 to 5% by mass.
[0107]
The haze of the optically anisotropic layer is generally 5.0% or less. Therefore, the optically anisotropic layer generally has 5.0% or less because the haze of the transparent support is low. The haze is measured according to ASTN-D1003-52. When the haze of the optically anisotropic layer is high, light leakage that appears to be caused by scattering occurs in the black display portion, resulting in a decrease in contrast. This tendency is remarkable when the incident light is tilted in the normal direction and in the upward direction of the image. Therefore, in order to prevent this, the haze is preferably 5% or less, more preferably 3% or less, and particularly preferably 1% or less. In general, haze is caused by a rough surface (fine irregularities, scratches) or internal non-uniformity (existence of minute portions having different refractive indexes). It is necessary to smooth the surface of the isotropic layer and reduce the nonuniformity of the internal refractive index. The optically anisotropic layer of the present invention has a low haze because an optically anisotropic layer having a smooth surface and a uniform interior is formed. In order to further reduce the haze, for example, it is preferable to form a protective layer or an adhesive layer on the optically anisotropic layer, or to appropriately select the conditions for forming the optically anisotropic layer. The smooth surface of the optically anisotropic layer can be easily obtained as described above.
[0108]
<Fixing of alignment state of liquid crystal compound>
It is preferable to fix the aligned liquid crystalline compound while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred.
Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970). The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution. Light irradiation for the polymerization of the liquid crystalline compound is preferably performed using ultraviolet rays. Irradiation energy is 20mJ / cm ² ~ 50J / cm ² Is preferably in the range of 20 to 5000 mJ / cm. ² More preferably, it is in the range of 100 to 800 mJ / cm. ² More preferably, it is in the range. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.
[0109]
<Alignment film>
The first and second optically anisotropic layers are preferably formed on alignment films provided on the first and second transparent supports, respectively. The alignment film has a function of defining the alignment direction of a liquid crystalline compound such as a discotic liquid crystalline compound to be applied by coating or the like. In the present invention, the alignment film is a polymer layer subjected to an alignment treatment such as a rubbing treatment, and the polymer has a group having vinyl, oxiranyl, aziridinyl, or aryl. The polymer is preferably polyvinyl alcohol.
[0110]
As an example of the alignment film, an alignment film made of polyvinyl alcohol will be described in detail.
The polyvinyl alcohol serving as the alignment film preferably has at least one hydroxyl group substituted with a group having a vinyl moiety, an oxiranyl moiety or an aziridinyl moiety. In general, the above-mentioned portion is composed of a polymer chain (carbon atom) of polyvinyl alcohol, an ether bond (-O-), a urethane bond (-OCONH-), an acetal bond ((-O-)). ₂ It is bonded via CH—) or an ester bond (—OCO—) [that is, a linking group]. A urethane bond, an acetal bond or an ester bond is preferred. It is preferable that vinyl, oxiranyl, aziridinyl or aryl is indirectly bonded to polyvinyl alcohol via the above bond, that is, a group having the above moiety is bonded to polyvinyl alcohol together with the bonding group as described below. Preferably it is.
[0111]
Polyvinyl alcohol preferably used as the alignment film is represented by the following general formula (I), (II) or (III) (however, (II) represents only the group).
[0112]
[Chemical 1]

[0113]
Where L ¹¹ Represents an ether bond, urethane bond, acetal bond or ester bond; R ¹¹ Represents an alkylene group or an alkyleneoxy group; L ¹² Is R ¹¹ And Q ¹¹ Q represents a linking group connecting ¹¹ Represents vinyl, oxiranyl or aziridinyl; at x1 + y1 + z1 = 100, x1 is 10-99.9 mol%, y1 is 0.01-80 mol%, and z1 is 0-70 mol%; and k and h are 0 or 1, respectively.
[0114]
In general formula (I), R ¹¹ Is generally an alkylene group of 1 to 24 carbon atoms, at least one non-adjacent CH ₂ Group is -O-, -CO-, -NH-, -NR ⁷ -(R ⁷ Represents alkyl having 1 to 4 carbon atoms or aryl having 6 to 15 carbon atoms), -S-, -SO ₂ -Or an alkylene group having 3 to 24 carbon atoms replaced by arylene having 6 to 15 carbon atoms, or alkyl, aryl, alkoxy, aryloxy, alkylthio, arylthio, halogen, alkylcarbonyl, arylcarbonyl, alkylsulfonyl, arylsulfonyl, Hydroxyl, mercapto, amino, alkylcarbonyloxy, arylcarbonyloxy, alkylsulfonyloxy, arylsulfonyloxy, alkylcarbonylthio, arylcarbonylthio, alkylsulfonylthio, arylsulfonylthio, alkylcarbonylamino, arylcarbonylamino, alkylsulfonylamino, It represents any of the above alkylene groups substituted with arylsulfonylamino, carboxy or sulfo.
[0115]
R ¹¹ Is -R ² -, -R ³ -(O-R ⁴ ) _t -OR ⁵ -, -R ³ -CO-R ⁶ -, -R ³ -NH-R ⁶ -, -R ³ -NR ⁷ -R ⁶ -, -R ³ -S-R ⁶ -, -R ³ -SO ₂ -R ⁶ -Or -R ³ -A ² -R ⁶ -(However, R ² , R ³ , R ⁴ , R ⁵ And R ⁶ Each represents an alkylene having 1 to 24 carbon atoms, and R ⁷ Represents alkyl having 1 to 12 carbon atoms or aryl having 6 to 15 carbon atoms; ² Represents an arylene having 6 to 24 carbon atoms, and t represents an integer of 0 to 4). In addition, R ¹¹ Is -R ² -Or -R ³ -(O-CH ₂ CH ₂ ) _t -(However, R ² And R ³ Are each alkylene having 1 to 12 carbon atoms and t is an integer of 0 to 2. In particular R ¹¹ Is preferably alkylene having 1 to 12 carbon atoms.
[0116]
The alkylene group may have a substituent. Examples thereof include alkyl having 1 to 24 carbon atoms, aryl having 6 to 24 carbon atoms, alkoxy having 1 to 24 carbon atoms, aryloxy having 6 to 24 carbon atoms, and alkylthio having 1 to 24 carbon atoms. Arylthio having 6 to 24 carbon atoms, halogen (F, Cl, Br), alkylcarbonyl having 2 to 24 carbon atoms, arylcarbonyl having 7 to 24 carbon atoms, alkylsulfonyl having 1 to 24 carbon atoms, carbon Arylsulfonyloxy having 6 to 24 atoms, hydroxyl, mercapto, amino, alkylcarbonyloxy having 2 to 24 carbon atoms, arylcarbonyloxy having 7 to 24 carbon atoms, alkylsulfonyloxy having 1 to 24 carbon atoms, carbon atom Arylsulfonyloxy having 6 to 24 carbon atoms, alkylcarbonylthio having 2 to 24 carbon atoms, carbon Arylcarbonylthio having 7 to 24 children, alkylsulfonylthio having 1 to 24 carbon atoms, arylsulfonylthio having 6 to 24 carbon atoms, alkylcarbonylamino having 2 to 24 carbon atoms, 7 to 24 carbon atoms Examples thereof include arylcarbonylamino, alkylsulfonylamino having 1 to 24 carbon atoms, arylsulfonylamino having 6 to 24 carbon atoms, carboxy and sulfo.
[0117]
Preferred examples of the substituent for the alkylene group include alkyl having 1 to 24 carbon atoms (particularly 1 to 12 carbon atoms), aryl having 6 to 24 carbon atoms (particularly 6 to 14 carbon atoms), and carbon atoms 2 -24 alkoxyalkyl (especially 2-12 carbon atoms). Examples of alkyl include methyl, ethyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, i-propyl, i-butyl, Mention may be made of sec-butyl, t-amyl and 2-ethylhexyl. Examples of alkyl substituted with 1-4 alkoxy include 2-methoxyethyl, 2- (2-methoxyethoxy) ethyl, 2- [2- (2-methoxyethoxy) ethoxy] ethyl, 2-n- Mention may be made of butoxyethyl, 2-ethoxyethyl, 2- (2-ethoxyethoxy) ethyl, 3-methoxypropyl, 3-ethoxypropyl, 3-n-propyloxypropyl and 2-methylbutyloxymethyl. Examples of aryl include phenyl, 2-tolyl, 3-tolyl, 4-tolyl, 2-anisyl, 3-anisyl, 4-anisyl, 2-biphenyl, 3-biphenyl, 4-biphenyl, 2-chlorophenyl, 3- Mention may be made of chlorophenyl, 4-chlorophenyl, 1-naphthyl and 2-naphthyl. Examples of the heterocyclic group include pyridyl, pyrimidyl, thiazolyl and oxazolyl.
[0118]
L ¹² Are —O—, —S—, —CO—, —O—CO—, —CO—O—, —O—CO—O—, —CO—O—CO—, —NRCO—, —CONR—, It preferably represents -NR-, -NRCONR-, -NRCO-O- or -OCONR- (wherein R represents a hydrogen atom or a lower alkyl group). -(L ¹² ) _h -Q ¹² Is vinyl, vinyloxy, acryloyl, methacryloyl, crotonoyl, acryloyloxy, methacryloyloxy, crotonoyloxy, vinylphenoxy, vinylbenzoyloxy, styryl, 1,2-epoxyethyl, 1,2-epoxypropyl, 2,3-epoxy Preference is given to propyl, 1,2-iminoethyl, 1,2-iminopropyl or 2,3-iminopropyl. Furthermore, vinyl, vinyloxy, acryloyl, methacryloyl, acryloyloxy, methacryloyloxy, crotonoyloxy, vinylbenzoyloxy, 1,2-epoxyethyl, 1,2-epoxypropyl, 2,3-epoxypropyl, 1,2-iminoethyl 1,2-iminopropyl or 2,3-iminopropyl is preferred. In particular, acryloyl, methacryloyl, acryloyloxy and methacryloyloxy are preferred.
[0119]
Under the condition of x1 + y1 + z1 = 100, x1 is preferably 50 to 99.9 mol%, and y1 is preferably 0.01 to 50 mol% (more preferably 0.01 to 20 mol%, particularly 0.01 to 10 mol%). %, Most preferably 0.01-5 mol%) and z1 is preferably 0.01-50 mol%.
[0120]
In the above general formula (I), L ¹¹ Is an acetal bond, the polyvinyl alcohol of the general formula (I) can be represented by the following general formula (Ia).
[0121]
[Chemical 2]

[0122]
Where L ¹¹ , R ¹¹ , L ¹² , Q ¹¹ , X1, y1, z1, k, and h have the same meaning as in the general formula (I).
[0123]
As the polyvinyl alcohol for the alignment film, those represented by the following general formula (III) are also preferable.
[0124]
[Chemical 3]

[0125]
Where L ³¹ Represents an ether bond, a urethane bond, an acetal bond or an ester bond; A ³¹ Represents an arylene group or an arylene group substituted with halogen, alkyl, alkoxy or substituted alkoxy (substituents of substituted alkoxy include alkoxy, aryl, halogen, vinyl, vinyloxy, acryloyl, methacryloyl, crotonoyl, acryloyl) Oxy, methacryloyloxy, crotonoyloxy, vinylphenoxy, vinylbenzoyloxy, styryl, 1,2-epoxyethyl, 1,2-epoxypropyl, 2,3-epoxypropyl, 1,2-iminoethyl, 1,2-imino Propyl or 2,3-iminopropyl); R ³¹ Is R ¹¹ Represents the same group as L; ³² L ¹² Represents the same group as ³¹ Q ¹¹ And x2 is from 10 to 99.9 mol%, y2 is from 0.01 to 80 mol%, and z2 is from 0 to 70 mol% under the condition of x2 + y2 + z2 = 100; and f, k1 And h1 are 0 or 1, respectively.
Especially A ³¹ Is preferably an arylene group having 6 to 24 carbon atoms, or an arylene group having 6 to 24 carbon atoms substituted with halogen, alkyl having 1 to 4 carbon atoms, or alkoxy having 1 to 4 carbon atoms. .
[0126]
A ³¹ In general, the number of carbon atoms in the arylene group is 6 to 24, preferably 6 to 12. Examples of the arylene group include 1,4-phenylene, 1,3-phenylene, 1,2-phenylene and 1,5-naphthylene, and 1,4-phenylene is particularly preferable. As the substituent for the arylene group, a halogen atom (F, Cl, Br or I), an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and an alkoxy having 1 to 4 carbon atoms, C6-C15 aryl, halogen, vinyl, vinyloxy, oxiranyl (1,2-epoxyethyl, 1,2-epoxypropyl, 2,3-epoxypropyl), aziridinyl (1,2-iminoethyl, 1,2 -Iminopropyl or 2,3-iminopropyl), acryloyl, methacryloyl, crotonoyl, acryloyloxy, methacryloyloxy, crotonoyloxy, vinylphenoxy, vinylbenzoyloxy or styryl substituted alkoxy groups having 1 to 4 carbon atoms Can be mentioned. A halogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms is preferable, and F, Cl, or methyl is particularly preferable. Under the condition x2 + y2 + z2 = 100, x2 is preferably 50 to 99.9 mol%, and y2 is preferably 0.01 to 50 mol% (particularly 0.01 to 20 mol%, particularly 0.01 to 10 mol%). %, Most preferably 0.01-5 mol%) and z2 is preferably 0.01-50 mol%.
[0127]
In the general formula (III), L ³¹ Is an acetal bond, the polyvinyl alcohol of the general formula (III) can be represented by the following general formula (IIIa).
[0128]
[Formula 4]

[0129]
Where A ³¹ , R ³¹ , L ³² , Q ³¹ , X2, y2, z2, f, k1, and h1 have the same meanings as those in formula (III).
[0130]
Furthermore, as the polyvinyl alcohol for the alignment film, those in which at least one hydroxyl group is substituted with a group of the following general formula (II) are also preferable.
[0131]
[Chemical formula 5]

[0132]
Where R ²¹ Represents an alkyl group or an alkyl group substituted with alkyl, alkoxy, allyl, halogen, vinyl, vinyloxy, oxiranyl, acryloyloxy, methacryloyloxy or crotonoyloxy; ²¹ Is an alkyl group, an alkyl group, an alkoxy group, or an alkyl, alkoxy, aryl, halogen, vinyl, vinyloxy substituted with an alkyl group, alkyl, alkoxy, aryl, halogen, vinyl, vinyloxy, oxiranyl, acryloyloxy, methacryloyloxy or crotonoyloxy Represents an alkoxy group substituted by oxiranyl, acryloyloxy, methacryloyloxy or crotonoyloxy; q is 0 or 1; and n is an integer of 0 to 4 (preferably 0 or 1, particularly 0) is there).
[0133]
R ²¹ Represents an alkyl group or an alkyl group substituted with alkyl, alkoxy, aryl or halogen; and W ²¹ Preferably represents an alkyl group, an alkyl group, an alkyl group, an alkoxy group, an aryl group or an alkyl group substituted with a halogen, or an alkoxy group substituted with an alkyl, alkoxy, allyl or a halogen.
[0134]
R ²¹ Represents an alkyl group substituted with vinyl, vinyloxy, oxiranyl, acryloyloxy, methacryloyloxy or crotonoyloxy; ²¹ Is an alkyl group, an alkyl group, an alkoxy group, or an alkyl, alkoxy, aryl, halogen, vinyl, vinyloxy substituted with an alkyl group, alkyl, alkoxy, aryl, halogen, vinyl, vinyloxy, oxiranyl, acryloyloxy, methacryloyloxy or crotonoyloxy And preferably represents an alkoxy group substituted with oxiranyl, acryloyloxy, methacryloyloxy or crotonoyloxy.
[0135]
The number of carbon atoms of the alkyl group or alkoxy group is preferably 1-24, and particularly preferably 1-12. Examples of the alkyl group include unsubstituted alkyl groups (eg, methyl, ethyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n- Dodecyl, i-propyl, i-butyl, sec-butyl, t-amyl and 2-ethylhexyl); alkyl groups substituted with 1-4 alkoxy (eg 2-methoxyethyl, 2- (2-methoxyethoxy) Ethyl, 2- [2- (2-methoxyethoxy) ethoxy] ethyl, 2-n-butoxyethyl, 2-ethoxyethyl, 2- (2-ethoxyethoxy) ethyl, 3-methoxypropyl, 3-ethoxypropyl, 3 -N-propyloxypropyl, 3-benzyloxypropyl and 2-methylbutyloxymethyl); aralkyl groups (eg 2-phenoxy Ruyl and 2- (4-n-butyloxyphenyl) ethyl); vinylalkyl groups (eg, vinylmethyl, 2-vinylethyl, 5-vinylpentyl, 6-vinylhexyl, 7-vinylheptyl and 8-vinyloctyl); Vinyloxyalkyl groups (eg 2-vinyloxyethyl, 5-vinyloxypentyl, 6-vinyloxyhexyl, 7-vinyloxyheptyl and 8-vinyloxyoctyl); oxiranylalkyl groups (eg 3,4- Epoxybutyl, 4,5-epoxypentyl, 5,6-epoxyhexyl, 6,7-epoxyheptyl, 7,8-epoxyoctyl and 6,7-epoxyoctyl); acryloyloxyalkyl groups (eg 2-acryloyloxy) Ethyl, 3-acryloyloxypropyl, 4 Acryloyloxybutyl, 5-acryloyloxypentyl, 6-acryloyloxyhexyl, 7-acryloyloxyheptyl and 8-acryloyloxyoctyl); methacryloyloxyalkyl groups (eg 2-methacryloyloxyethyl, 3-methacryloyloxypropyl, 4- Methacryloyloxybutyl, 5-methacryloyloxypentyl, 6-methacryloyloxyhexyl, 7-methacryloyloxyheptyl and 8-methacryloyloxyoctyl); crotonoyloxyalkyl groups (eg 2-crotonoyloxyethyl, 3-crotonoyloxypropyl) 4-crotonoyloxybutyl, 5-crotonoyloxypentyl, 6-crotonoyloxyhexyl, 7-crotonoyloxyheptyl And 8-crotonoyloxyoctyl).
[0136]
OR ²¹ The position of substitution with the benzene ring is preferably 3 or 4. The polyvinyl alcohol having the group of the general formula (II) has a repeating unit having the group of the general formula (II) in a range of 0.1 to 10 mol% (particularly 0.1 to 5 mol%) of all repeating units. In the range).
[0137]
The group of the general formula (II) can be introduced into polyvinyl alcohol by reacting a carboxylic acid derivative having the following general formula (IIa) group with polyvinyl alcohol.
[0138]
[Chemical 6]

[0139]
In the general formula (IIa), R ²¹ , W ²¹ , N and q have the same meanings as in the general formula (II), and X represents a group (which can activate X-CO-) necessary to form a carboxylic acid site activated form. Represent. The group represented by X is described, for example, in Nobuo Izumiya et al., “Peptide Synthesis (Chapter 5, published by Maruzen 1975)”. For example, when an active ester is formed, examples of X include 4-nitrophenoxy and N-oxysuccinimide. In the case of forming an acid anhydride, symmetric acid anhydrides and mixed acid anhydrides can be mentioned. Examples of X in the case of mixed acid anhydrides include methanesulfonyloxy, trifluoroacetyloxy, ethyloxy Mention may be made of carbonyloxy. Examples of X in the case of an acid halide include a chlorine atom and a bromine atom. These compounds having an atomic group represented by X are not necessarily isolated, and those generated in the reaction system may be used as they are. As the carboxylic acid derivative, mixed acid anhydrides and acid halides are preferable, and methanesulfonyloxy type mixed acid anhydrides and acid chlorides are particularly preferable.
[0140]
Specific examples of the polyvinyl alcohol represented by the general formulas (I), (II) and (III), and (Ia), (IIa) and (IIIa) include the paragraphs of JP-A-9-152509. Examples compounds described in 0060-0066 and 0072-0095 are included. The synthesis method is described in paragraphs 0070 and 0096-0120 of the above publication.
[0141]
In the present invention, the alignment film may be composed of the above-mentioned specific polyvinyl alcohol alone or may be composed of a mixture with a conventionally known alignment film polymer. In the case of a mixture, generally known polymers can be used at 90% by mass or less of the total polymer, but it is particularly preferable that they are used at 70% by mass or less.
[0142]
In addition to the specific polyvinyl alcohol, examples of the polymer having a polymerizable group that can be used as an alignment film in the present invention include polyimide having vinyl, oxiranyl, or aziridinyl, and gelatin having vinyl, oxiranyl, or aziridinyl. . These polymers can be synthesized using a polymer having a hydroxyl group or an amino group introduced in the same manner as the synthesis of the specific polyvinyl alcohol. For example, the introduction of a polymerizable group into polyimide has a polymerizable group used in the synthesis of the specific polyvinyl alcohol by reacting a polyhydric alcohol with a carboxyl group of a polyamic acid to introduce a hydroxyl group into the polyamic acid. The reaction can be carried out by reacting a compound (for example, a compound of the general formula (IIa) or an isocyanate compound thereof) with the hydroxyl group of the polyamic acid and then polymerizing the polyamic acid having this polymerizable group. Introduction of a polymerizable group into gelatin can be carried out by reacting an ε-amino group of a lysine residue of gelatin with a compound having a polymerizable group used in the synthesis of the specific polyvinyl alcohol.
[0143]
Examples of other known polymers that can be used in the alignment film of the present invention include polymethyl methacrylate, acrylic acid / methacrylic acid copolymer, styrene / maleimide copolymer, polyvinyl alcohol and modified polyvinyl alcohol, poly ( N-methylolacrylamide), styrene / vinyl toluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, vinyl acetate / vinyl chloride copolymer, ethylene / vinyl acetate copolymer Mention may be made of carboxymethylcellulose, polyethylene, polypropylene and polycarbonate.
[0144]
In the present invention, the alignment film is formed by applying a coating liquid containing the specific polyvinyl alcohol, which is an alignment film forming material, onto a transparent support, followed by drying by heating to form a polymer layer, and rubbing the polymer layer. It can form by performing orientation processing, such as processing. Examples of the coating method include a spin coating method, a dip coating method, an extrusion coating method, and a bar coating method. The E-type coating method is particularly preferable. The film thickness is preferably 0.1 to 10 μm. Heat drying can be performed at 20 ° C. to 110 ° C., preferably 60 ° C. to 100 ° C., particularly preferably 80 ° C. to 100 ° C. The drying time can be 1 minute to 36 hours. Preferably, it is 5 minutes to 30 minutes.
[0145]
The alignment film can be obtained by subjecting the polymer layer to an alignment treatment such as a rubbing treatment using a treatment method widely adopted as a liquid crystal alignment treatment step of LCD as described above. The alignment film functions to define the alignment direction of a liquid crystal compound such as a liquid crystal discotic compound provided thereon. The rubbing treatment is generally performed by rubbing the surface of the polymer layer in a certain direction using paper, gauze, felt, rubber, velvet, fibers of polyamide, polyester, or the like. Preferably, it is performed by rubbing the surface of the polymer layer using a rubbing roll wound with a rubbing cloth such as velvet. The rubbing may be performed by a batch method or a continuous method.
[0146]
The liquid crystal display device of the present invention includes a first transparent protective film, a first polarizing film, a first transparent support and a first optical anisotropic layer, and / or a second transparent protective film, a second polarizing film, a second After integrating the transparent support and the second optically anisotropic layer, it can be produced in combination with a liquid crystal cell.
For example, when the polarizing film is produced by the above-described oblique stretching method that is performed continuously, a long polarizing film is obtained. This long polarizing film is wound into a roll to form a roll polarizing film. On the other hand, an optically anisotropic layer made of a liquid crystalline compound is formed on a long transparent support and wound into a roll. A roll-shaped laminate is obtained by using a roll-shaped transparent support with an optically anisotropic layer, and laminating them together and continuously integrating them. By cutting (punching) the roll-shaped laminate into a desired size, a member in which the polarizing film, the transparent support, and the optically anisotropic layer are integrated is obtained. Further, at least one optically anisotropic layer composed of a liquid crystalline compound is formed on a long transparent support at the same time or after the long transparent protective film is bonded to the long polarizing film. A transparent support with an optically anisotropic layer on which a conductive layer is formed is laminated to obtain a laminate, which is cut (punched) into a desired size, thereby forming a transparent protective film, a polarizing film, a transparent support and an optical A member in which the anisotropic layer is integrated is obtained. The liquid crystal display device of the present invention can be manufactured by arranging the prepared pair of members with a liquid crystal cell interposed therebetween. In the present invention, the retardation (Re) value of the optically anisotropic layer can be defined by the formula (1) (formula (1) in claim 4).
[0147]
【Example】
The present invention will be described more specifically with reference to the following examples. The materials, reagents, ratios, operations, and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.
[0148]
[Example 1]
(Production of transparent support and cellulose acetate film for transparent protective film)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.
Cellulose acetate solution composition
100 parts by mass of cellulose acetate having an acetylation degree of 60.7 to 61.1%
7.8 parts by mass of triphenyl phosphate (plasticizer)
Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by mass
336 parts by mass of methylene chloride (first solvent)
Methanol (second solvent) 29 parts by mass
1-butanol (third solvent) 11 parts by mass
[0149]
In another mixing tank, 16 parts by mass of the following retardation increasing agent, 92 parts by mass of methylene chloride and 8 parts by mass of methanol were added and stirred while heating to prepare a retardation increasing agent solution. A dope was prepared by mixing 474 parts by mass of the cellulose acetate solution with 25 parts by mass of the retardation increasing agent solution and stirring sufficiently. The addition amount of the retardation increasing agent was 3.5 parts by mass with respect to 100 parts by mass of cellulose acetate.
[0150]
Retardation raising agent
[Chemical 7]

[0151]
The obtained dope was cast using a band stretching machine. After the film surface temperature on the band reaches 40 ° C., the film is dried with warm air of 70 ° C. for 1 minute, and the film is dried from the band with 140 ° C. of drying air for 10 minutes. A cellulose acetate film (thickness: 60 μm) was prepared. About the produced cellulose acetate film (transparent support body, transparent protective film), the Re retardation value and Rth retardation value in wavelength 546nm were measured using the ellipsometer (M-150, JASCO Corporation make). Re was 2 nm (variation ± 1 nm), and Rth was 78 nm (variation ± 3 nm). Furthermore, Re of each wavelength of 400 nm to 700 nm was in the range of 2 ± 1 nm, and Rth of each wavelength of 400 nm to 700 nm was in the range of 78 ± 2 nm.
The produced cellulose acetate film was immersed in a 2.0N potassium hydroxide solution (25 ° C.) for 2 minutes, neutralized with sulfuric acid, washed with pure water, and then dried. The surface energy of the cellulose acetate film was determined by a contact method and found to be 63 mN / m. Thus, a cellulose acetate film for a transparent support and a transparent protective film was produced.
[0152]
(Preparation of alignment layer)
On this cellulose acetate film, a coating solution of the following composition was 28 ml / m with a # 16 wire bar coater. ² Applied. The film was dried at 25 ° C. for 60 seconds, 60 ° C. warm air for 60 seconds, and 90 ° C. hot air for 150 seconds. The alignment film thickness after drying was 1.1 μm. Further, the surface roughness (Ra) of the alignment film was measured with an atomic force microscope (AFM: Atomic Force Microscope, SPI3800N, manufactured by Seiko Instruments Inc.), and found to be 1.147 nm. Next, the formed film was rubbed in a 45 ° direction with respect to the slow axis of the cellulose acetate film (measured at a wavelength of 632.8 nm).
[0153]
Alignment film coating solution composition
20 parts by mass of the following modified polyvinyl alcohol
361 parts by weight of water
119 parts by mass of methanol
Glutaraldehyde (crosslinking agent) 0.5 parts by mass
[0154]
Modified polyvinyl alcohol
[Chemical 8]

[0155]
(Formation of optically anisotropic layer)
On the alignment film, a liquid crystal discotic compound 1,2,1 ′, 2 ′, 1 ″, 2 ″ -tris [4,5-di (vinylcarbonyloxybutoxybenzoyloxy) phenylene (JP-A-8-50206) (8), m = 4) 41.01 g of Exemplified Compound TE-8 described in paragraph No. 0044, ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 4.06 g , 0.90 g of cellulose acetate butyrate (CAB551-0.2, manufactured by Eastman Chemical Co.), 0.23 g of cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co., Ltd.), photopolymerization initiator (Irgacure 907, Ciba Geigy Co., Ltd.) 1.35 g, Sensitizer (Kayacure DETX, Nippon Kayaku Co., Ltd.) 0.45 g The coating liquid was dissolved in methyl ethyl ketone g, was applied with a # 4 wire bar. This was affixed to a metal frame, and then heated in a thermostatic bath at 130 ° C. for 2 minutes to orient the discotic compound. Next, using a 120 W / cm high pressure mercury lamp at 60 ° C., UV irradiation was performed for 1 minute to polymerize the discotic compound. Thereafter, the mixture was allowed to cool to room temperature to form an optically anisotropic layer (film thickness 1.95 μm).
[0156]
With respect to the produced optically anisotropic layer, Re (retardation value) measured at a wavelength of 632.8 nm was 46 nm. The angle (tilt angle) between the disk surface and the first transparent support surface increased from the first transparent support side toward the air interface (hybrid orientation), and averaged 38 °.
In addition, when the number of orientation defects in the optically anisotropic layer was observed using a 100 times magnifier, 1.3 defects / m of defects of 70 μm or more were observed. ² It was the following.
The retardation (Re) value for the optically anisotropic layer can be defined by the above formula (1) (formula (1) in claim 4).
[0157]
(Preparation of polarizing film)
A PVA film having an average degree of polymerization of 2,400 and a film thickness of 100 μm was washed with ion exchange water at 15 to 17 ° C. for 60 seconds, and surface moisture was scraped off with a stainless steel blade. It was immersed in an aqueous solution of 0.77 g / l iodine and 60.0 g / l potassium iodide for 55 seconds at 40 ° C. while correcting the concentration so that the concentration was constant. After dipping in an aqueous solution of 0.5 g / l, potassium iodide 30 g / l, and zinc chloride 1.8 g / l at 40 ° C. for 90 seconds, both surfaces of the film are scraped off with a stainless steel blade, and contained in the film In a state where the moisture content distribution was 2% or less (the average moisture content of the PVA film at this time was 32%), it was introduced into a tenter stretching machine having the configuration shown in FIG. After feeding 100 m at a conveyance speed of 4 m / min and stretching up to 5 times in an atmosphere of 60 ° C. and 95%, the tenter is bent as shown in FIG. 4 with respect to the stretching direction. After drying in an atmosphere of ° C., it was detached from the tenter. The moisture content of the PVA film after drying was 1.5%. The difference in transport speed between the left and right tenter clips was less than 0.05%, and the angle between the center line of the introduced film and the center line of the film sent to the next process was 46 °. Here, | L1-L2 | is 0.7 m, W is 0.7 m, and | L1-L2 | = W. The substantial stretching direction Ax-Cx at the tenter outlet was inclined by 45 ° with respect to the center line 22 of the film sent to the next process. Wrinkles and film deformation at the tenter exit were not observed. The thickness of the film after stretching and drying was 19 μm.
[0158]
(Lamination of transparent protective film)
The above-mentioned optical film in which the above-mentioned obliquely stretched polarizing film is 3 cm from the width direction and is cut with a cutter, and then both surfaces thereof are saponified using an aqueous solution of PVA (PVA-117H manufactured by Kuraray Co., Ltd.) 3% A transparent support having an anisotropic layer and a saponified cellulose acetate film for transparent protective film prepared above were bonded together, and further heated at 70 ° C. for 10 minutes to provide a cellulose acetate film on both sides with an effective width of 650 mm. A polarizing plate was obtained.
The polarizing plate performance excluding the optically anisotropic layer of the polarizing plate has a visible light transmittance of 43.2 and a polarization degree {(Tp−Tc) / (Tp + Tc)}. ^1/2 Is 0.9997 (where Tp is parallel transmittance, Tc is orthogonal transmittance), before and after standing at 60 ° C., humidity 90% RH atmosphere for 500 hours and 80 ° C., dry atmosphere for 500 hours The change rate of the light transmittance was 1% or less based on the absolute value, and the change rate of the polarization degree was 0.05% or less based on the absolute value.
[0159]
The absorption axis direction of the obtained polarizing film was inclined 45 ° with respect to the longitudinal direction. The polarizing plate had a transmittance at 550 nm of 42.3% and a degree of polarization of 99.97%. Further, as shown in FIG. 10, when cut into a size of 310 × 233 mm, a polarizing plate having an absorption axis inclined by 45 ° with respect to the side with an area efficiency of 91.5% could be obtained. In addition, no color omission stripes were observed with the naked eye.
[0160]
(Laminated arrangement with liquid crystal cell)
The polarizing plate was peeled off from a commercially available liquid crystal display device (6E-A3, manufactured by Sharp Corporation), the TN type liquid crystal cell was taken out, and the polarizing plate produced as described above was arranged as shown in FIG. 1 and FIG. Laminated. Specifically, the angle formed by the slow axis of the first transparent protective film (longitudinal direction of the film) and the absorption axis of the first polarizing film is + 45 °, and similarly the slow axis of the first transparent support (longitudinal direction of the film) And an angle formed by the first polarizing film absorption axis is + 45 °, and an angle formed by the first polarizing film absorption axis and the orientation control direction (rubbing angle) of the first optical anisotropic layer made of the discotic liquid crystalline compound is 0 ° or The angle was 180 °. The angle formed between the upper rubbing axis 6 of the liquid crystal cell and the slow axis 4 of the first transparent protective film was set to + 45 ° or −45 °. Similarly, the angle formed by the slow axis of the second transparent protective film (longitudinal direction of the film) and the absorption axis of the second polarizing film is + 45 °, and the slow axis of the second transparent support (longitudinal direction of the film) and the second The angle between the polarizing film absorption axis is + 45 °, and the angle between the second polarizing film absorption axis and the orientation control direction (rubbing angle) of the second optical anisotropic layer made of the discotic liquid crystalline compound is 0 ° or 180 °. did. The angle formed between the lower rubbing axis of the liquid crystal cell and the slow axis of the second transparent protective film was set to + 45 ° or −45 °.
The angle formed between the liquid crystal cell rubbing axis and the slow axis of the transparent support (the longitudinal direction of the film) varies depending on the liquid crystal cell twist angle and the liquid crystal cell driving voltage because the optimum angle for achieving the maximum contrast changes. There is no limit. Furthermore, the angle formed by the first polarizing film absorption axis and the second polarizing film absorption axis was 90 °. The liquid crystal cell thus produced was returned to the above-mentioned liquid crystal display device (6E-A3, manufactured by Sharp Corporation), and the liquid crystal display device 5 was produced with the second transparent protective layer on the backlight side. The above angle allows a deviation of around plus or minus 5 ° in consideration of variations in the process of forming an optically anisotropic layer made of a liquid crystal cell or a discotic liquid crystalline compound.
[0161]
(Viewing angle measurement)
The luminance and contrast ratio of the produced liquid crystal display device were measured with a spectral radiance meter (BM-5 manufactured by Topcon Corporation). The contrast ratio was calculated from the ratio between the white display luminance and the black display luminance. The viewing angle was measured every 5 ° and the azimuth was measured every 10 ° in a dark room. When expressing the results on a graph, an isocontrast curve diagram in which the angles of the same contrast values are connected by a solid line was used.
[0162]
(Evaluation of the effect on the viewing angle of deviation (axial deviation) from an angle of 45 ° between the slow axis of the first transparent support and the absorption axis of the first polarizing film)
Liquid crystal display devices 1 to 4 and 6 to 9 shown in Table 1 were produced in the same manner as the liquid crystal display device 5 except that the direction of the slow axis of the first transparent support was changed. Table 1 shows the measurement results of the liquid crystal display devices 1 to 9 in the range of the contrast ratio of 10 to 1 or more in the front contrast ratio and the horizontal viewing angle. From the results shown in Table 1, it can be seen that the axis deviation angle ± 5 ° is the same and the present invention is effective. It can also be seen that a deviation of around ± 5 ° is allowed. The same result was obtained when the slow axis of the second transparent support and the axis of the second polarizing film were misaligned.
[0163]
[Table 1]

[0164]
[Example 2]
<Measurement results of influence of Re value of first and second transparent supports>
As shown in Table 2, liquid crystal display devices 10 to 14 were produced in the same manner as the liquid crystal display device 5 except that the Re values of the first and second transparent supports were changed. The Re value was adjusted by controlling the film thickness, stretching strength, additives, etc., and Rth was kept constant at 78 nm. With respect to the liquid crystal display devices 5 and 10 to 14, the measurement results in the range of the contrast ratio of 10 to 1 or more in the front contrast ratio of the liquid crystal display device and the horizontal viewing angle are shown in Table 2.
From the results shown in Table 2, it can be seen that as the Re value of the transparent support increases, the viewing angle deteriorates, and the range where the contrast ratio is 10 to 1 or more is narrowed particularly in the left-right direction. In addition, the symmetry of the left and right contrasts in the range of 10 to 1 or more deteriorates. When the Re value of the transparent support was larger than 5 nm, an opening of 10 ° or more occurred in the difference in the range, and asymmetry or deterioration of the viewing angle was also confirmed by visual observation.
[0165]
[Table 2]

[0166]
[Example 3]
<Measurement result of influence of Rth value of transparent support>
As shown in Table 3, the Rth value of the second transparent support was set to 78 nm, and the Rth value of the first transparent support was changed. 18 was produced. The Rth value was adjusted by controlling the film thickness, stretching strength, additives, etc., and Re was made constant at 2 nm. Table 3 shows the measurement results of the viewing angle at which the contrast ratio is 10 to 1 or more in the front contrast ratio and the horizontal viewing angle for each liquid crystal display device with the protective film Rth value changed. From the results in the table, the same characteristics were obtained when the Rth value was 76 nm ± 5 nm. When Rth is greatly changed, Rth may be set between 50 and 200 nm in order to obtain a contrast range of 10: 1 or more in the horizontal direction of 50 ° or more. At this time, a film having a Re value of 2 nm was used.
[0167]
[Table 3]

[0168]
[Example 4]
(Measurement result of influence of Re value deviation of first transparent support and second transparent support)
As shown in Table 4, the thickness of the optically anisotropic layer was changed to 1.43 μm by changing the coating amount of the optically anisotropic layer (Re value was 46 nm, the angle between the disk surface and the first transparent support surface (inclination) The liquid crystal display device was manufactured in the same manner as the liquid crystal display device 5 except that the angle was 39 ° on average and the Re values of the first transparent support and the second transparent support were changed as shown in Table 4. . At this time, Rth of the first transparent support and the second transparent support was 78 nm. Table 4 shows the measurement results of the front contrast ratio of the obtained liquid crystal display device. From the results shown in Table 4, the front contrast decreases when there is a difference in the Re values between the first transparent support and the second transparent support. In order to obtain a high contrast of 1000 to 1, the difference in Re value between the first transparent support and the second transparent support needs to be within ± 3 nm. Further, as the absolute value of the Re value increases, the asymmetry of the viewing angle characteristic becomes remarkable. Therefore, the absolute value of Re is desirably 5 nm or less.
[0169]
[Table 4]

[0170]
[Example 5]
A liquid crystal display device 1 to a liquid crystal display device 1 except that the first transparent protective film and the second transparent protective film of Example 1 were replaced with those obtained by saponifying a commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.). A liquid crystal display device was produced in the same manner as in Example 9, and the same evaluation as in Example 1 was performed. The obtained results were almost the same as those in Example 1.
Moreover, the polarizing plate performance except the optically anisotropic layer of the polarizing plate used above was evaluated similarly to Example 1. As a result, the visible light transmittance is 43.6, and the degree of polarization {(Tp−Tc) / (Tp + Tc)}. ^1/2 Is 0.9996 (where Tp is parallel transmittance, Tc is orthogonal transmittance), before and after standing at 60 ° C., humidity 90% RH atmosphere for 500 hours and 80 ° C., dry atmosphere for 500 hours The change rate of the light transmittance was 1% or less based on the absolute value, and the change rate of the polarization degree was 0.05% or less based on the absolute value.
[0171]
[Comparative Example 1]
The angle formed by the slow axis of the first transparent protective film and the first transparent support and the absorption axis of the first polarizing film is substantially parallel, and the slow axis of the second transparent protective film and the second transparent support and the second polarized light are formed. The angle formed by the film absorption axes was made substantially parallel, and the other configurations were the same as those in Example 1. The viewing angle of the contrast ratio of 10: 1 or more of the liquid crystal display device was 70 ° or more in both the left and right directions, and a front contrast ratio of 1200 was obtained. However, it is understood that the yield is lowered in this configuration when the polarizing plate is cut out from the roll. It was.
[0172]
【The invention's effect】
According to the present invention, it is to provide a liquid crystal display device capable of remarkably reducing the manufacturing cost by using a polarizing plate that has a wide viewing angle and can be manufactured at low cost, and in particular, improves the yield in the punching process. An object of the present invention is to provide a liquid crystal display device having a wide viewing angle using a polarizing plate that can be used.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a liquid crystal display device of the present invention.
FIG. 2 is a schematic view showing an example of a polarizing plate of the present invention.
FIG. 3 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.
FIG. 4 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.
FIG. 5 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.
FIG. 6 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.
FIG. 7 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.
FIG. 8 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.
FIG. 9 is a schematic plan view showing a state of punching a conventional polarizing plate.
FIG. 10 is a schematic plan view showing a state of punching out the polarizing plate of the present invention.
[Explanation of symbols]
1A First polarizing plate (consisting of a first transparent protective film, a first polarizing film, and a first support)
2A Absorption axis of the first polarizing plate
3A First optically anisotropic layer
4A Orientation control direction of the first optically anisotropic layer
5A Liquid crystal cell observation side substrate
6A Observation side substrate Liquid crystal alignment rubbing direction
7A Liquid crystal molecules
8A LCD cell backlight side substrate
9A Backlight side substrate Liquid crystal alignment rubbing direction
10A Second optically anisotropic layer
11A Orientation control direction of second optical anisotropic layer
12A transparent protective film
13A Transparent protective film slow axis
14A Polarizing plate polarizing film
15A Polarization film absorption axis
16A Crossing angle between slow axis and absorption axis
17A transparent support
18A Transparent support slow axis
19A Second polarizing plate (consisting of a second support, a second polarizing film, and a second transparent protective film)
20A Absorption axis of the second polarizing plate
(B) Direction of film introduction
(B) Film transport direction to the next process
(A) Step of introducing a film
(B) Step of stretching the film
(C) Sending the stretched film to the next process
A1 Position of biting into film holding means and starting point of film stretching (substantially holding start point: right)
B1 Biting position of film holding means (left)
C1 Film stretch starting position (substantially holding start point: left)
Cx film release position and film stretching end point reference position (actual holding release point: left)
Ay Film drawing end point reference position (substantially holding release point: right)
| L1-L2 | Stroke difference between left and right film holding means
W Actual width at the end of the film stretching process
θ Angle between stretching direction and film traveling direction
11 Center line of introduction film
12 Center line of film sent to the next process
13 Trajectory of film holding means (left)
14 Trajectory of film holding means (right)
15 Introducing film
16 Film sent to the next process
17, 17 'Left and right film holding start (biting) point
18, 18 'Departing point from left and right film holding means
21 Centerline of introduction film
22 Center line of film sent to the next process
23 Trajectory of film holding means (left)
24 Trajectory of film holding means (right)
25 Introducing film
26 Film sent to the next process
27, 27 'Left and right film holding start (biting) points
28, 28 'Departing point from left and right film holding means
33, 43, 53, 63 Trajectory of film holding means (left)
34, 44, 54, 64 Trajectory of film holding means (right)
35, 45, 55, 65 Introduction side film
36, 46, 56, 66 Film sent to the next process
71 Absorption axis (stretching axis)
72 Longitudinal direction
81 Absorption axis (stretching axis)
82 Longitudinal direction

Claims (15)

1st transparent protective film, 1st polarizing film, 1st transparent support body, 1st optically anisotropic layer which consists of one or more layers formed from liquid crystalline compounds, liquid crystal cell, 1 layer or more formed from liquid crystalline compounds The second optically anisotropic layer, the second transparent support, the second polarizing film, and the second transparent protective film are laminated in this order, and the absorption axes of the first polarizing film and the second polarizing film are the first, respectively. The slow axis of the transparent support and the second transparent support is neither parallel nor perpendicular, and the slow axis of the first transparent support and the slow axis of the second transparent support are perpendicular to each other. Liquid crystal display device. At least one of the first optical anisotropic layer and the second optical anisotropic layer is a layer made of a compound having a discotic structural unit, and the disc surface of the discotic structural unit is inclined with respect to the transparent support surface. 2. The liquid crystal display device according to claim 1, wherein an angle formed by the disc surface of the discotic structural unit and the transparent support surface changes in the thickness direction of the optically anisotropic layer. The crossing angle between the slow axis of the first transparent support and the absorption axis of the first polarizing film is 10 ° or more and less than 90 °, and the slow axis of the second transparent support and the absorption axis of the second polarizing film The liquid crystal display device according to claim 1, wherein the crossing angle is 10 ° or more and less than 90 °. 4. The liquid crystal display device according to claim 1, wherein at least one of the first transparent support and the second transparent support satisfies the following conditions (A) to (C): 5.
(A) Re (retardation) value represented by the following formula (1) is -5 nm or more and 5 nm or less, and dispersion of Re is ± 3 nm or less of the average value Re value = (nx−ny) × d (1)
(B) Rth value represented by the following formula (2) is 50 nm or more and 200 nm or less, and variation in Rth is ± 5 nm or less of an average value Rth value = {(nx + ny) / 2−nz} × d (2)
(In the formula (2), nx is the refractive index in the slow axis direction in the plane of the transparent support, ny is the refractive index in the direction orthogonal to nx in the plane of the transparent support, and nz is the thickness direction of the transparent support. The refractive index of d represents the thickness of the transparent support.)
(C) Thickness 20 μm or more and 100 μm or less The Re (retardation) value of 400 nm to 700 nm of at least one of the first transparent support and the second transparent support is ± 2 nm or less with respect to the Re average value of 400 nm to 700 nm. A liquid crystal display device according to 1. 6. The Rth value of 400 nm to 700 nm of at least one of the first transparent support and the second transparent support is ± 3 nm or less with respect to the Rth average value of 400 nm to 700 nm. Liquid crystal display device. The liquid crystal display device according to claim 1, wherein at least one of the first transparent support and the second transparent support is made of a cellulose acylate film. At least one of the first polarizing film and the second polarizing film holds both ends of the continuously supplied polymer film by the holding means, and the holding means advances in the longitudinal direction of the film under the condition satisfying the following formula (3) 2. A long polarizing film produced by stretching the film while applying tension to the film and making the difference between the left and right conveying speeds in the longitudinal direction of the stretched film less than 1%. 8. A liquid crystal display device according to any one of.
| L2-L1 |> 0.4W (3)
(In the formula (3), L1 represents the trajectory of the holding means from the substantial holding start point to the substantial releasing point of the one end of the polymer film; L2 represents the substantial other end of the polymer film; The holding means trajectory from the initial holding start point to the substantial holding release point; and W denotes the distance between the two substantially holding release points.) The polymer film has a volatile content before stretching of 10% or more, and the elongated polarizing film is formed by stretching the polymer film 2 to 10 times and then contracted by 10% or more. The liquid crystal display device according to claim 8. The liquid crystal display device according to claim 8, wherein the polymer film is made of a polyvinyl alcohol-based polymer and has a thickness before stretching of 75 μm to 200 μm. The liquid crystal according to any one of claims 8 to 10, wherein the long polarizing film is prepared by adsorbing a polarizing element on a polyvinyl alcohol polymer film before or after stretching. Display device. At least the first polarizing film, the first transparent support and the first optically anisotropic layer, and / or the second polarizing film, the second transparent support and the second optically anisotropic layer have the long shape. A polarizing film and a long transparent support with an optically anisotropic layer in which one or more optically anisotropic layers made of a liquid crystalline compound are formed on a long transparent support are bonded together. The liquid crystal display device according to any one of claims 8 to 11, wherein the long laminated body is cut. At least the first transparent protective film and the first polarizing film, and / or the second transparent protective film and the second polarizing film are produced by stretching and shrinking the polymer film and further reducing the volatile content rate. The long laminate formed by post-heating after laminating a long transparent protective film on a long polarizing film is cut, and the long laminated body is cut. A liquid crystal display device according to item. The first transparent protective film, the first polarizing film, the first transparent support and the first optically anisotropic layer, and / or the second transparent protective film, the second polarizing film, the second transparent support and the second optically different film. The isotropic layer stretches the polymer film, shrinks it, and further bonds the long transparent protective film to the long polarizing film prepared by reducing the volatile content rate, or after bonding. Cutting a laminate in which a long transparent support with an optically anisotropic layer is formed by forming one or more optically anisotropic layers made of a liquid crystalline compound on a long transparent support. The liquid crystal display device according to claim 8, wherein the liquid crystal display device is a liquid crystal display device. The liquid crystal display device according to claim 1, wherein the liquid crystal cell is a TN mode or OCB mode liquid crystal cell.

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