JP4303827B2 - Production method of retardation plate - Google Patents
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Description
【０００１】
【発明の技術分野】
本発明は、液晶セルの光学補償による視角特性の改善に好適な位相差板の製造方法に関する。
【０００２】
【発明の背景】
液晶による複屈折で視角によりコントラスト等が変化することの防止を目的に、液晶セルに位相差板を配置して複屈折に基づく光学特性を補償し視角特性を改善する技術が提案されている。かかる補償用の位相差板は、通例一軸や二軸等による延伸フィルムからなるが、満足できるものが提供されていない現状である。
【０００３】
ポリスチレン等の負の複屈折特性を示す熱可塑性樹脂、すなわち延伸方向と直交する方向に屈折率が増大する性質を示す熱可塑性樹脂からなるフィルムを二軸延伸したものでは、液晶表示装置用等の耐熱性に優れるものを得ることが困難である。また前記樹脂の一軸延伸フィルムでは、２枚以上を用いて積層する必要があり光軸の制御などその製造効率に乏しい難点がある。
【０００４】
【発明の技術的課題】
本発明は、製造効率や耐熱性に優れて液晶セルによる複屈折を高度に補償できる薄型の位相差板を得ることを課題とする。
【０００５】
【課題の解決手段】
本発明は、熱可塑性樹脂からなる長尺フィルムの片面又は両面に１枚又は２枚以上の熱収縮性フィルムを接着した状態で、ロール速比１以下のロール延伸機を介して熱収縮性フィルムの収縮力の作用下に長尺フィルムを収縮処理すること、及び前記収縮処理した長尺フィルムをテンターによるグリップ把持下に熱収縮性フィルムの収縮力を作用させて長尺フィルムの幅方向を０．７倍以上ないし１．０倍未満の倍率Ａで収縮させた後、その収縮後のグリップ把持部を除いたフィルム幅を１００として、式：（１００−倍率Ａ×１００）×０．２以下を満足する延伸率（％）にて当該幅方向を延伸拡幅処理することを特徴とする位相差板の製造方法を提供するものである。
【０００６】
前記の方法により本発明は、面内の主屈折率をｎx、ｎy、厚さ方向の主屈折率をｎzとし、かつｎx＞ｎyとしたとき、式：（ｎx−ｎz）／（ｎx−ｎy）で定義されるＮｚが−０．２以下であり、かつ面内での光軸のズレが±３度以内である位相差板を得ることを目的とする。
【０００７】
【発明の効果】
本発明による方法によれば、上記Ｎｚが−０．２以下で光軸のズレが±３度以内の薄型の位相差板を製造効率よく得ることができ、それを用いて液晶セルの複屈折に基づく視角による表示特性の変化を高度に補償して、広い視角範囲でコントラスト等の視認性に優れる液晶表示装置を得ることができる。また正の複屈折特性を示す熱可塑性樹脂からなるフィルムを用いて耐熱性にも優れる位相差板を得ることができる。
【０００８】
【発明の実施形態】
本発明による製造方法は、熱可塑性樹脂からなる長尺フィルムの片面又は両面に１枚又は２枚以上の熱収縮性フィルムを接着した状態で、ロール速比１以下のロール延伸機を介して熱収縮性フィルムの収縮力の作用下に長尺フィルムを収縮処理すること、及び前記収縮処理した長尺フィルムをテンターによるグリップ把持下に熱収縮性フィルムの収縮力を作用させて長尺フィルムの幅方向を０．７倍以上ないし１．０倍未満の倍率Ａで収縮させた後、その収縮後のグリップ把持部を除いたフィルム幅を１００として、式：（１００−倍率Ａ×１００）×０．２以下を満足する延伸率（％）にて当該幅方向を延伸拡幅処理して位相差板を得るものである。
【０００９】
処理対象の長尺フィルムとしては、熱可塑性樹脂からなる延伸処理が可能なフィルムが用いられ、耐熱性に優れる位相差板を得る点よりは、延伸方向の屈折率が高くなる正の複屈折特性を示す熱可塑性樹脂からなるものが好ましく用いられる。
【００１０】
前記した正の複屈折特性を示す熱可塑性樹脂については特に限定はなく、適宜なものを用いうる。ちなみにその例としてはポリカーボネート、ポリビニルアルコール、セルロース系樹脂、ポリエチレンテレフタレートやポリエチレンナフタレートの如きポリエステル、ポリアリレート、ポリイミド、ノルボルネン系樹脂、ポリスルホン、ポリエーテルスルホン、ポリプロピレンの如きポリオレフィンなどがあげられる。就中、非晶質で耐熱性に優れ、透明性に優れる、特に光透過率が８０％以上のフィルムを形成しうる熱可塑性樹脂が好ましく用いうる。
【００１１】
長尺フィルムは、例えば流延法等のキャスティング法や、押出法などの適宜な方式で形成したものであってよい。キャスティング法等の溶液製膜法が厚さムラや配向歪ムラ等の少ないフィルムを得る点などより好ましい。長尺フィルムの厚さは、目的とする位相差などにより適宜に決定しうるが、一般には１０〜５００μm、就中２０〜３００μmとされる。
【００１２】
熱収縮性フィルムとしては、例えば熱可塑性樹脂からなるフィルムの一軸や二軸等による延伸フィルムなどよりなる適宜なものを用いることができ、特に限定はない。表面平滑性や長尺フィルムの収縮制御性に優れる熱可塑性樹脂からなるものが好ましく用いられる。
【００１３】
熱収縮性フィルムは、その収縮力等に応じて長尺フィルムの片面又は両面に１枚又は２枚以上の適宜な数で接着することができる。その接着処理は、加熱による収縮力の作用下に長尺フィルムをその長さ方向や幅方向に収縮させた後の容易な剥離性などの点より粘着層による接着処理が好ましい。その粘着層には、熱収縮性フィルムの収縮温度にて必要な接着力を発揮する適宜なものを用いうる。
【００１４】
長尺フィルムに接着した熱収縮性フィルムの収縮処理は、先ずロール延伸機を介して行う。その処理温度は、長尺フィルムのガラス転移温度の近傍、就中ガラス転移温度の±２０℃以内の温度範囲で行うことが処理操作の制御性などの点より好ましい。またかかる点より用いる熱収縮性フィルムは、その処理温度以下の温度で熱収縮を開始するものが好ましい。
【００１５】
前記のロール延伸機を介した熱収縮性フィルムの収縮処理は、ロール速比１以下の条件で行う。これにより長尺フィルムを長さ方向と幅方向（面内方向）に収縮させて上記したＮｚ−０．２以下を満足する位相差板を得ることができる。そのロール速比が１超では、当該Ｎｚを満足させにくい。なお当該Ｎｚは、面内の主屈折率をｎx、ｎy、厚さ方向の主屈折率をｎzとし、かつｎx＞ｎyとしたとき、式：（ｎx−ｎz）／（ｎx−ｎy）にて定義される（以下同じ）。
【００１６】
次に前記のロール延伸機を介し収縮処理した長尺フィルムは、テンターによるグリップを介した把持下に、それに接着した熱収縮性フィルムの加熱による収縮力の作用下に更に収縮処理する。その処理温度や、用いる熱収縮性フィルムについては上記したロール延伸機による場合に準じうる。
【００１７】
またテンターを介した収縮処理時の熱収縮性フィルムについては、上記のロール延伸機を介した収縮処理時に用いたものをそのまま用いることもできるし、別個に貼り替えることもできる。前者のそのまま用いる方式が長尺フィルムのロール延伸機とテンターを介した収縮処理を一連に行って目的の位相差板を連続製造できる点などより好ましい。
【００１８】
前記のテンターと熱収縮性フィルムを介した長尺フィルムの収縮処理は、その幅方向に基づいてロール延伸機による収縮処理後の長尺フィルム幅の０．７倍以上ないし１．０倍未満の倍率Ａとなるように行われる。これにより上記したＮｚ−０．２以下を満足する位相差板を得ることができ、その延伸倍率Ａが前記範囲外では当該Ｎｚを満足させにくい。
【００１９】
一方、本発明においては前記テンターを介した収縮処理後の長尺フィルムに対して、更にテンターによるグリップを介した長尺フィルムの把持下にその幅方向を延伸拡幅処理する。従って本発明においてはテンターを介し長尺フィルムを幅方向に収縮させた後、その幅を延伸処理を介して拡幅する。これにより−０．２以下のＮｚを満足させつつ、面内での光軸のズレが小さい、特にそのズレが±３度以内にある位相差板を得ることができる。
【００２０】
すなわち、正の複屈折特性を示す熱可塑性樹脂からなるフィルムをロール延伸機と熱収縮性フィルムを介し面内方向に収縮させた場合、面内にネッキングによる光軸のズレが生じる。その光軸のズレは、液晶表示装置のコントラストを低下させ、ＴＮモードやＯＣＢモードやＶＡモード等を含むＴＦＴ駆動方式では位相差ムラよりもコントラストに大きく影響する。
【００２１】
テンターと熱収縮性フィルムを介した面内方向の収縮処理で前記ロール延伸機を介した処理で発生した光軸のズレはある程度修正されるが、そのテンターによる処理にてもフイルム幅の両端部を把持するグリップによる変形の規制力が長さ方向とフィルムの中央部とで相違してフィルムの幅方向で搬送速度に差が生じ、光軸のズレ修正に差が発生する。
【００２２】
テンターを介した長尺フィルム幅方向の収縮後の拡幅処理は、長尺フィルムの長さ方向と幅方向の収縮・延伸をバランスさせてロール延伸機とテンターを介した収縮処理で発生した光軸のズレを全体的に修正するものであり、その結果、−０．２以下のＮｚを満足し、かつ光軸のズレが小さい位相差板を得ることができる。
【００２３】
前記した拡幅処理は、収縮処理後のグリップ把持部を除いた長尺フィルムの幅を１００としたとき、式：（１００−倍率Ａ×１００）×０．２以下を満足する延伸率（％）の範囲で行うことが必要である。その延伸率が前記の範囲を超えるとボーイング歪みが発生して、光軸のズレはむしろ大きくなる。
【００２４】
なお上記において、テンターを介した長尺フィルムの収縮処理とその幅方向の拡幅処理は、別個の工程で行うこともできるし、一連の工程で行うこともできる。またそれらの場合における拡幅処理では、熱収縮性フィルムを接着したまま行うこともできるし、剥離除去した後に行うこともできる。熱収縮性フィルムを接着したまま収縮処理と拡幅処理を一連に行って目的の位相差板を連続製造する方式が製造効率などの点より好ましい。
【００２５】
上記のように本発明による位相差板は、−０．２以下のＮｚを満足し、かつ面内での光軸のズレが±３度以内であるものからなり、かかる位相差板は薄型化等の点より単層物として形成されていることが好ましいが、同種又は異種の位相差板の積層体として形成されていてもよい。また等方性の透明な樹脂層やガラス層等で保護ないし補強されたものであってもよい。
【００２６】
本発明による位相差板は、例えば正面方向でのコントラストの低下を防止した斜視方向位相差の打消し補償や、正面方向と斜視方向の位相差の打消し補償等の、ＴＮ型やＳＴＮ型やπ型等の各種の液晶セルにおける複屈折による視角特性の補償などに好ましく用いうる。
【００２７】
なお位相差板は、その実用に際し例えば偏光板や拡散板、アンチグレア層や反射防止膜、保護層や保護板などの適宜な光学層と積層した光学部材として用いることもできる。またかかる位相差板を用いての液晶表示装置の形成は、従来に準じて行うことができる。
【００２８】
すなわち液晶表示装置は一般に、液晶セルと光学補償用の位相差板、及び必要に応じての偏光板や照明システム等の構成部品を適宜に組立てて駆動回路を組込むことなどにより形成されるが、本発明においては上記の如く、本発明による位相差板を光学補償用のものに用いて、それを液晶セルの少なくとも片側に設ける点を除いて特に限定はなく、従来に準じた形態の液晶表示装置とすることができる。
【００２９】
【実施例】
実施例１
ホスゲンとビスフェノールＡの重縮合物からなる分子量約８万のポリカーボネートの二塩化メチレン２０重量％溶液を、スチールドラム上に連続的に流延し、それを順次剥取って乾燥させ、厚さ６０μmで位相差がほぼ０のポリカーボネートフィルムを得、そのフィルムの両面に二軸延伸ポリエステルフィルムをアクリル系粘着層を介し接着してロール速比０．９６のロール延伸機を介し１５０℃で収縮処理した後、それをテンターのグリップを介した把持下に１６２℃で幅方向を０．９２倍に収縮させ、ついで０．５％〔（１００−０．９２×１００）×０．０６３〕の延伸率で延伸処理して二軸延伸ポリエステルフィルムを剥離し、位相差板を連続して得た。
【００３０】
実施例２
１６２℃で幅方向を０．９５５倍に収縮させた後０．８％〔（１００−９５．５）×０．１７８〕の延伸率で延伸処理したほかは実施例１に準じて位相差板を得た。
【００３１】
比較例１
ロール速比１．０５のロール延伸機にて１５５℃で収縮させ、その後のテンターを介した収縮処理及び延伸処理を施さないほかは実施例１に準じて位相差板を得た。
【００３２】
比較例２
ロール延伸機による収縮処理のみで、その後のテンターを介した収縮処理及び延伸処理を施さないほかは実施例１に準じて位相差板を得た。
【００３３】
比較例３
テンターによる幅方向の収縮処理を０．９３倍とし、その後の延伸処理を２．０％〔（１００−９３）×０．２８６〕の延伸率としたほかは実施例１に準じて位相差板を得た。
【００３４】
評価試験
実施例、比較例で得た位相差板について、フィルム面内と厚さ方向の主屈折率ｎx、ｎy、ｎzをナトリウムＤ線を光源に用いたアッベ屈折計（アタゴ社製、４型）にて調べてＮｚを算出すると共に、フィルム面内の光軸のズレを調べた（オーク製作所社製、ＡＤＲ−１００ＸＹ）。
【００３５】
前記の結果を次表に示した。
ＴＮ型液晶セルの両側に、実施例１，２で得た位相差板を介して偏光板を配置し、正面方向のコントラストと視角変化による表示特性を調べたところ、コントラストに優れて広い視角範囲で表示特性に変化はなく、視認性に優れる高表示品位の液晶表示装置であった。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of manufacturing a retardation plate suitable for improving viewing angle characteristics by optical compensation of a liquid crystal cell.
[0002]
BACKGROUND OF THE INVENTION
In order to prevent the contrast and the like from changing due to the viewing angle due to the birefringence by the liquid crystal, a technique has been proposed in which a retardation plate is disposed in the liquid crystal cell to compensate the optical characteristics based on the birefringence and to improve the viewing angle characteristics. Such a retardation plate is usually made of a uniaxial or biaxial stretched film, but a satisfactory one is not provided.
[0003]
A thermoplastic resin exhibiting negative birefringence characteristics such as polystyrene, that is, a biaxially stretched film made of a thermoplastic resin exhibiting a property of increasing the refractive index in the direction orthogonal to the stretching direction, is used for liquid crystal display devices, etc. It is difficult to obtain a product having excellent heat resistance. Further, the uniaxially stretched film of the resin needs to be laminated by using two or more sheets, and there is a difficulty in its production efficiency such as control of the optical axis.
[0004]
[Technical Problem of the Invention]
An object of the present invention is to obtain a thin retardation plate that is excellent in manufacturing efficiency and heat resistance and can highly compensate birefringence due to a liquid crystal cell.
[0005]
[Means for solving problems]
In the present invention, one or two or more heat-shrinkable films are bonded to one or both sides of a long film made of a thermoplastic resin, and the heat-shrinkable film is passed through a roll stretching machine having a roll speed ratio of 1 or less. Shrinking the long film under the action of the shrinking force of the film, and applying the shrinking force of the heat-shrinkable film to the long film subjected to the shrinking treatment while gripping the grip with a tenter, the width direction of the long film is reduced to 0. After shrinking at a magnification A of 7 times or more to less than 1.0 times, the film width excluding the grip grip portion after the shrinkage is defined as 100, and the formula: (100−magnification A × 100) × 0.2 or less The present invention provides a method for producing a retardation film, wherein the width direction is stretched and widened at a stretching ratio (%) satisfying the above.
[0006]
By the above-described method, the present invention has the following formula: (nx−nz) / (nx−ny), where the in-plane main refractive index is nx, ny, the main refractive index in the thickness direction is nz, and nx> ny. ) and the Nz is -0.2 or less defined by, and deviation of the optical axis in the plane is shall be the purpose of obtaining a phase difference plate is within 3 degrees ±.
[0007]
【The invention's effect】
According to the method of the present invention, a thin retardation plate with Nz of −0.2 or less and an optical axis misalignment of within ± 3 degrees can be obtained with high production efficiency. A change in display characteristics due to a viewing angle based on the above is highly compensated, and a liquid crystal display device having excellent visibility such as contrast in a wide viewing angle range can be obtained. Moreover, the phase difference plate excellent also in heat resistance can be obtained using the film which consists of a thermoplastic resin which shows a positive birefringence characteristic.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In the production method according to the present invention, one or two or more heat-shrinkable films are bonded to one side or both sides of a long film made of a thermoplastic resin, and heated through a roll stretching machine having a roll speed ratio of 1 or less. Shrinking the long film under the action of the shrinking force of the shrinkable film, and applying the shrinking force of the heat-shrinkable film to the shrinkable long film while gripping it with a tenter, the width of the long film After shrinking the direction at a magnification A of 0.7 times or more to less than 1.0 times, the film width excluding the grip gripping portion after the shrinkage is defined as 100, and the formula: (100−magnification A × 100) × 0 The phase difference plate is obtained by stretching and widening the width direction at a stretching ratio (%) satisfying .2 or less.
[0009]
As the long film to be processed, a film made of a thermoplastic resin that can be stretched is used, and the positive birefringence characteristic in which the refractive index in the stretching direction is higher than the point of obtaining a retardation plate having excellent heat resistance. What consists of the thermoplastic resin which shows is preferably used.
[0010]
There is no limitation in particular about the thermoplastic resin which shows the above-mentioned positive birefringence characteristic, A suitable thing can be used. Examples thereof include polycarbonate, polyvinyl alcohol, cellulose resin, polyester such as polyethylene terephthalate and polyethylene naphthalate, polyarylate, polyimide, norbornene resin, polyolefin such as polysulfone, polyethersulfone and polypropylene. In particular, a thermoplastic resin that can form a film that is amorphous, excellent in heat resistance, excellent in transparency, and in particular having a light transmittance of 80% or more can be preferably used.
[0011]
The long film may be formed by an appropriate method such as a casting method such as a casting method or an extrusion method. A solution casting method such as a casting method is more preferable in that a film with less thickness unevenness, orientation strain unevenness and the like is obtained. The thickness of the long film can be appropriately determined depending on the target retardation or the like, but is generally 10 to 500 μm, especially 20 to 300 μm.
[0012]
As the heat-shrinkable film, for example, an appropriate film made of a stretched film such as a uniaxial film or a biaxial film made of a thermoplastic resin can be used, and there is no particular limitation. What consists of a thermoplastic resin which is excellent in surface smoothness and shrinkage controllability of a long film is used preferably.
[0013]
The heat-shrinkable film can be bonded to one or both sides of the long film with an appropriate number of one or two or more depending on the shrinkage force or the like. The adhesive treatment is preferably an adhesive treatment with an adhesive layer from the viewpoint of easy peelability after the long film is shrunk in the length direction and width direction under the action of the contraction force by heating. As the pressure-sensitive adhesive layer, an appropriate layer that exhibits a necessary adhesive force at the shrinkage temperature of the heat-shrinkable film can be used.
[0014]
The shrinkage treatment of the heat-shrinkable film adhered to the long film is first performed via a roll stretching machine. The treatment temperature is preferably in the vicinity of the glass transition temperature of the long film, especially within a temperature range within ± 20 ° C. of the glass transition temperature, from the viewpoint of controllability of the treatment operation. Moreover, the heat-shrinkable film used from this point is preferably one that starts heat-shrinking at a temperature not higher than the processing temperature.
[0015]
The shrink treatment of the heat-shrinkable film via the roll stretching machine is performed under the condition that the roll speed ratio is 1 or less. As a result, the long film can be shrunk in the length direction and the width direction (in-plane direction) to obtain a retardation plate satisfying Nz−0.2 or less. If the roll speed ratio exceeds 1, it is difficult to satisfy the Nz. The Nz is expressed by the formula: (nx−nz) / (nx−ny) where nx and ny are the main refractive indexes in the plane, nz is the main refractive index in the thickness direction, and nx> ny. Defined (the same shall apply hereinafter).
[0016]
Next, the long film subjected to the shrinkage treatment through the roll stretching machine is further subjected to the shrinkage treatment under the action of the shrinkage force due to the heating of the heat-shrinkable film adhered thereto while being gripped through the grip by the tenter. About the processing temperature and the heat-shrinkable film to be used, it can apply according to the case where it uses an above-mentioned roll extending machine.
[0017]
Moreover, about the heat-shrinkable film at the time of the shrinkage | contraction process via a tenter, what was used at the time of the shrinkage | contraction process via said roll extending | stretching machine can be used as it is, and it can also replace separately. The former method is more preferable because the target retardation plate can be continuously produced by carrying out a series of shrinking treatments via a roll stretcher and a tenter for a long film.
[0018]
The shrinking treatment of the long film via the tenter and the heat-shrinkable film is 0.7 times or more to less than 1.0 times the long film width after the shrinking treatment by the roll stretching machine based on the width direction. The magnification A is performed. Thereby, a retardation plate satisfying the above-described Nz−0.2 or less can be obtained, and it is difficult to satisfy the Nz when the draw ratio A is outside the range.
[0019]
On the other hand, in the present invention, the wide film is stretched and widened in the width direction while gripping the long film through the grip by the tenter, with respect to the long film after the shrinking process through the tenter. Therefore, in the present invention, after the long film is shrunk in the width direction through the tenter, the width is widened through the stretching process. As a result, it is possible to obtain a phase difference plate that satisfies Nz of −0.2 or less and has a small optical axis deviation in the plane, in particular, a deviation within ± 3 degrees.
[0020]
That is, when a film made of a thermoplastic resin exhibiting positive birefringence characteristics is shrunk in the in-plane direction via a roll stretching machine and a heat-shrinkable film, the optical axis shifts due to necking in the plane. The deviation of the optical axis lowers the contrast of the liquid crystal display device, and in the TFT driving method including the TN mode, the OCB mode, the VA mode, etc., the contrast is more greatly affected than the phase difference unevenness.
[0021]
Although the optical axis misalignment caused by the treatment via the roll stretching machine is corrected to some extent by the in-plane shrinkage treatment via the tenter and the heat-shrinkable film, both ends of the film width are also affected by the treatment with the tenter. The deformation restricting force due to the grip for gripping the film is different between the length direction and the central portion of the film, resulting in a difference in the conveyance speed in the width direction of the film and a difference in correcting the deviation of the optical axis.
[0022]
The widening process after shrinking in the width direction of the long film through the tenter is the optical axis generated by the shrinking process through the roll stretching machine and the tenter by balancing the shrinkage and stretching in the length direction and the width direction of the long film. As a result, it is possible to obtain a retardation plate that satisfies Nz of −0.2 or less and has a small optical axis shift.
[0023]
The above-mentioned widening treatment is a stretch ratio (%) satisfying the formula: (100−magnification A × 100) × 0.2 or less, where the width of the long film excluding the grip holding part after the shrinking treatment is 100. It is necessary to carry out within the range. When the stretching ratio exceeds the above range, bowing distortion occurs, and the optical axis shift is rather increased.
[0024]
In the above, the shrinking process of the long film via the tenter and the widening process in the width direction can be performed in separate steps or can be performed in a series of steps. Moreover, the widening process in those cases can be performed with the heat-shrinkable film adhered, or after peeling and removal. From the standpoint of production efficiency and the like, a method of continuously producing a target retardation plate by carrying out a series of shrinkage treatment and widening treatment while the heat-shrinkable film is adhered is preferable.
[0025]
As described above, the retardation plate according to the present invention satisfies Nz of −0.2 or less and has an in-plane optical axis misalignment within ± 3 degrees, and the retardation plate is thinned. However, it may be formed as a laminate of the same or different kinds of retardation plates. Further, it may be protected or reinforced with an isotropic transparent resin layer or glass layer.
[0026]
The phase difference plate according to the present invention is a TN type, STN type, etc., such as compensation for compensation of a perspective direction retardation that prevents a decrease in contrast in the front direction, compensation compensation for a phase difference between the front direction and the perspective direction. It can be preferably used for compensation of viewing angle characteristics due to birefringence in various liquid crystal cells such as π type.
[0027]
The retardation plate can also be used as an optical member laminated with an appropriate optical layer such as a polarizing plate, a diffusion plate, an antiglare layer, an antireflection film, a protective layer or a protective plate in practical use. In addition, the liquid crystal display device using such a retardation plate can be formed according to conventional methods.
[0028]
That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a retardation plate for optical compensation, and a polarizing plate and an illumination system as necessary, and incorporating a drive circuit. In the present invention, as described above, there is no particular limitation except that the retardation plate according to the present invention is used for optical compensation, and is provided on at least one side of the liquid crystal cell. It can be a device.
[0029]
【Example】
Example 1
A 20% by weight solution of methylene dichloride in polycarbonate having a molecular weight of about 80,000 consisting of a polycondensate of phosgene and bisphenol A is continuously cast on a steel drum, which is peeled off and dried in order to obtain a thickness of 60 μm. After obtaining a polycarbonate film having a phase difference of almost 0, a biaxially stretched polyester film was bonded to both sides of the film via an acrylic adhesive layer, and subjected to shrinkage treatment at 150 ° C. via a roll stretching machine having a roll speed ratio of 0.96. Then, it is contracted 0.92 times in the width direction at 162 ° C. while being gripped through the grip of the tenter, and then stretched at a stretch ratio of 0.5% [(100−0.92 × 100) × 0.063]. The biaxially stretched polyester film was peeled off by stretching, and retardation plates were continuously obtained.
[0030]
Example 2
A phase difference plate according to Example 1 except that the width direction was contracted 0.955 times at 162 ° C. and then stretched at a stretch rate of 0.8% [(100-95.5) × 0.178]. Got.
[0031]
Comparative Example 1
A phase difference plate was obtained in the same manner as in Example 1 except that the film was shrunk at 155 ° C. with a roll stretching machine having a roll speed ratio of 1.05 and subjected to subsequent shrinking and stretching processes via a tenter.
[0032]
Comparative Example 2
A phase difference plate was obtained in the same manner as in Example 1 except that only the shrinkage treatment by a roll stretching machine was performed and the subsequent shrinkage treatment and stretching treatment via a tenter were not performed.
[0033]
Comparative Example 3
Retardation plate according to Example 1 except that the contraction treatment in the width direction with a tenter is 0.93 times and the subsequent stretching treatment is 2.0% [(100-93) × 0.286]. Got.
[0034]
For the retardation plates obtained in the evaluation test examples and comparative examples, the Abbe refractometers using the sodium D line as the light source for the main refractive indices nx, ny, nz in the film plane and in the thickness direction (type 4 manufactured by Atago Co., Ltd. ) To calculate Nz, and the optical axis deviation in the film plane was examined (ADR-100XY, manufactured by Oak Manufacturing Co., Ltd.).
[0035]
The results are shown in the following table.
Polarizing plates were arranged on both sides of the TN type liquid crystal cell via the phase difference plates obtained in Examples 1 and 2, and the display characteristics due to the contrast in the front direction and the change in viewing angle were examined. Thus, the display characteristics did not change, and the liquid crystal display device had high display quality and excellent visibility.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11325499A JP4303827B2 (en) | 1999-04-21 | 1999-04-21 | Production method of retardation plate |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11325499A JP4303827B2 (en) | 1999-04-21 | 1999-04-21 | Production method of retardation plate |
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| JP2000304925A JP2000304925A (en) | 2000-11-02 |
| JP4303827B2 true JP4303827B2 (en) | 2009-07-29 |
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| JP2004269842A (en) | 2002-09-30 | 2004-09-30 | Tosoh Corp | Transparent heat-resistant resin optical material and film |
| US9796822B2 (en) | 2007-04-13 | 2017-10-24 | Lg Chem, Ltd. | Optical films, retardation films, and liquid crystal display comprising the same |
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| JP2818983B2 (en) * | 1990-10-24 | 1998-10-30 | 日東電工株式会社 | Method for producing birefringent film |
| JP3342517B2 (en) * | 1992-10-27 | 2002-11-11 | 株式会社クラレ | Method for producing PVA-based film and optical film |
| JPH06194646A (en) * | 1992-12-25 | 1994-07-15 | Fuji Photo Film Co Ltd | Tn type liquid crystal display element provided with optical compensation film |
| JP2812153B2 (en) * | 1993-06-28 | 1998-10-22 | 住友金属工業株式会社 | Heat treatment method for near β type titanium alloy |
| JP3168850B2 (en) * | 1993-12-22 | 2001-05-21 | 住友化学工業株式会社 | Method for producing retardation film |
| JPH08278410A (en) * | 1995-04-10 | 1996-10-22 | Sumitomo Chem Co Ltd | Optical anisotropic film, method for producing the same, and liquid crystal display device |
| JPH08304628A (en) * | 1995-04-27 | 1996-11-22 | Nitto Denko Corp | Phase difference plate, laminated polarizing plate and liquid crystal display device |
| JPH09318815A (en) * | 1996-05-27 | 1997-12-12 | Nitto Denko Corp | Production of optical film, laminated polarizing plate and liquid crystal display device |
| JPH10206636A (en) * | 1997-01-17 | 1998-08-07 | Nitto Denko Corp | Polarizing element, lighting device and liquid crystal display device |
| JPH10319235A (en) * | 1997-05-16 | 1998-12-04 | Nitto Denko Corp | Polarizing element, lighting device, and liquid crystal display device |
| JP2000111732A (en) * | 1998-10-05 | 2000-04-21 | Sekisui Chem Co Ltd | Production of three-dimensional double refractive film |
| JP2000284118A (en) * | 1999-03-29 | 2000-10-13 | Fuji Photo Film Co Ltd | Elliptic polarization plate and stn liquid crystal display device |
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