JP4400770B2 - Solution casting method - Google Patents

Description

【００６７】
劣化防止剤の添加量は、０．００１〜５％が好ましく、０．０１〜１％がより好ましい。添加量が０．００１％未満であると添加効果が少なく、添加量が５％を超えると、原料コストが上昇して不利である。
【００６８】
前記微粒子粉体としては、シリカ、カオリン、タルク、ケイソウ土、石英、炭酸カルシウム、硫酸バリウム、酸化チタン、アルミナなどを目的に応じ、任意に用いることができる。これら微粒子粉体はドープに添加する前に、高速ミキサー、ボールミル、アトライター、超音波分散機等、任意の手段でバインダー溶液中に分散を行うことが好ましい。バインダーとしてはセルロースアシレートが好ましい。紫外線吸収剤等、他の添加物と共に分散を行うことも好ましい。分散溶媒は任意であるが、ドープ溶媒と近い組成であることが好ましい。
【００６９】
微粒子粉体の数平均粒径は０．０１〜１００μｍが好ましく、０．１〜１０μｍが特に好ましい。上記の分散液はセルロースアシレート溶解工程に同時に添加しても良いし、任意の工程でドープに添加できるが、紫外線吸収剤同様スタティックミキサ等を用い、流延直前に添加する形態が好ましい。
【００７０】
微粒子粉体の含有量は、セルロースアシレートに対して０．００１〜５質量％であることが好ましく、０．０１〜１質量％であることがより好ましい。添加量が０．００１質量％未満では添加効果を十分に発揮することができず、添加量が５質量％を超えると、外観面状が悪くなる場合がある。
【００７１】
前記離型剤としては、界面活性剤が有効であり、リン酸系、スルフォン酸系、カルボン酸系、ノニオン系、カチオン系など特に限定されない。これらは、例えば特開昭６１−２４３８３７号などに記載されている。離型剤の添加量は、セルロースアシレートに対して０．００１〜２質量％が好ましく、０．０１〜１質量％がより好ましい。添加量が０．００１質量％未満であれば添加効果を十分に発揮することができず、添加量が２質量％を超えると、析出したり、不溶解物を生じたりすることがある。
【００７２】
ノニオン系界面活性剤としては、ポリオキシエチレン、ポリオキシプロピレン、ポリオキシブチレン、ポリグリシジルやソルビタンをノニオン性親水性基とする界面活性剤であり、具体的には、ポリオキシエチレンアルキルエーテル、ポリオキシエチレンアルキルフェニールエーテル、ポリオキシエチレン−ポリオキシプロピレングリコール、多価アルコール脂肪酸部分エステル、ポリオキシエチレン多価アルコール脂肪酸部分エステル、ポリオキシエチレン脂肪酸エステル、ポリグリセリン脂肪酸エステル、脂肪酸ジエタノールアミド、トリエタノールアミン脂肪酸部分エステルを挙げることができる。
【００７３】
アニオン系界面活性剤としてはカルボン酸塩、硫酸塩、スルフォン酸塩、リン酸エステル塩であり、代表的なものとしては脂肪酸塩、アルキルベンゼンスルフォン酸塩、アルキルナフタレンスルフォン酸塩、アルキルスルフォン酸塩、α−オレフィンスルフォン酸塩、ジアルキルスルフォコハク酸塩、α−スルフォン化脂肪酸塩、Ｎ−メチルーＮオレイルタウリン、石油スルフォン酸塩、アルキル硫酸塩、硫酸化油脂、ポリオキシエチレンアルキルエーテル硫酸塩、ポリオキシエチレンアルキルフェニールエーテル硫酸塩、ポリオキシエチレンスチレン化フェニールエーテル硫酸塩、アルキルリン酸塩、ポリオキシエチレンアルキルエーテルリン酸塩、ナフタレンスルフォン酸塩ホルムアルデヒド縮合物などである。
【００７４】
カチオン系界面活性剤としてはアミン塩、４級アンモニウム塩、ピリジュム塩などを挙げることができ、第一〜第３脂肪アミン塩、第４級アンモニウム塩（テトラアルキルアンモニウム塩、トリアルキルベンジルアンモニウム塩、アルキルピリジウム塩、アルキルイミダゾリウム塩など）を挙げることができる。両性系界面活性剤としてはカルボキシベタイン、スルフォベタインなどであり、Ｎ−トリアルキル−Ｎ−カルボキシメチルアンモニウムベタイン、Ｎ−トリアルキル−Ｎ−スルフォアルキレンアンモニウムベタインなどである。
【００７５】
前記フッ素系界面活性剤を添加することにより、帯電防止効果を発揮することができる。フッ素系界面活性剤の添加量は、セルロースアシレートに対して０．００２〜２質量％が好ましく、０．０１〜０．５質量％がより好ましい。添加量が０．００２質量％未満であれば添加効果を十分に発揮することができず、添加量が２質量％を超えると、析出したり、不溶解物を生じたりすることがある。
【００７６】
本発明においては、レターデーション上昇剤（光学特性調整剤）を添加することができる。レターデーション上昇剤を添加することにより、光学異方性をコントロールすることができる。レターデーション上昇剤は、セルロースアシレートフイルムのレターデーションを調整するため、少なくとも二つの芳香族環を有する芳香族化合物を使用することが好ましい。芳香族化合物は、セルロースアシレート１００質量部に対して、０．０１〜２０質量部の範囲で使用する。芳香族化合物は、セルロースアセレート１００質量部に対して、０．０５〜１５質量部の範囲で使用することが好ましく、０．１〜１０質量部の範囲で使用することがさらに好ましい。二種類以上の芳香族化合物を併用してもよい。芳香族化合物の芳香族環には、芳香族炭化水素環に加えて、芳香族性ヘテロ環を含む。
【００７７】
芳香族炭化水素環は、６員環（すなわち、ベンゼン環）であることが特に好ましい。芳香族性ヘテロ環は一般に、不飽和ヘテロ環である。芳香族性ヘテロ環は、５員環、６員環又は７員環であることが好ましく、５員環又は６員環であることがさらに好ましい。芳香族性ヘテロ環は一般に、最多の二重結合を有する。ヘテロ原子としては、窒素原子、酸素原子及び硫黄原子が好ましく、窒素原子が特に好ましい。芳香族性ヘテロ環の例には、フラン環、チオフェン環、ピロール環、オキサゾール環、イソオキサゾール環、チアゾール環、イソチアゾール環、イミダゾール環、ピラゾール環、フラザン環、トリアゾール環、ピラン環、ピリジン環、ピリダジン環、ピリミジン環、ピラジン環及び１，３，５−トリアジン環が含まれる。
【００７８】
本発明においては、着色剤を添加することができる。着色剤を添加することにより、感光材料支持体等に用いる場合、ライトパイピングを防止することができる。着色剤の添加量は、セルロースアシレートに対する重量割合で１０〜１０００ｐｐｍが好ましく、５０〜５００ｐｐｍが更に好ましい。
【００７９】
また、本発明におけるドープには、ルシウム、マグネシウムなどのアルカリ土類金属の塩などの熱安定剤、帯電防止剤、難燃剤、滑剤、油剤などを、必要に応じて適宜添加することができる。
【００８０】
本発明の溶液製膜方法により製造されるフィルムの光学特性について記す。まず、フィルムの面内のレターデーション（Ｒｅ）について記すと、その測定法はエリプソメーター（偏光解析計ＡＥＰ−１００：島津製作所（株）製）を用いて、波長６３２．８ｎｍにおける面内の縦横の屈折率差にフィルム膜厚さを乗じたものであり、下記の式で求められる。
Ｒｅ＝（ｎｘ−ｎｙ）×ｄ
ｎｘ：横方向の屈折率
ｎｙ：縦方向の屈折率
【００８１】
レターデーション（Ｒｅ）は、小さいほど面内方向の光学異方性がないことを示し、０〜３００ｎｍの範囲で用途に応じて用いられる。また、フィルムの厚さ方向のレターデーション（Ｒｔｈ）も重要であり、波長６３２．８ｎｍにおける厚さ方向の複屈折にフィルム膜厚さを乗じたものであり、下記の式で求められる。
Ｒｔｈ＝｛（ｎｘ＋ｎｙ）／２−ｎｚ｝×ｄ
ｎｘ：横方向の屈折率
ｎｙ：縦方向の屈折率
ｎｚ：厚さ方向の屈折率
【００８２】
厚さ方向の屈折率が小さいほど、厚さ方向の光学異方性がないことを示すが、その使用用途によって好ましい範囲は定まる。一般には、本発明により製造されたセルロースアシレートフィルムのＲｔｈは１００μｍ当たり、０ｎｍ〜６００ｎｍであり、さらには０ｎｍ〜４００ｎｍで用いられる。
【００８３】
本発明の溶液製膜方法で製造されるフィルムは、例えば、偏光板保護膜、光学補償シート、ＡＲ、ＬＲ、ＡＧ膜用支持体フィルム等の光学用途フィルム、写真感光材料用支持体フィルムとしても利用することができる。
【００８４】
本発明の溶液製膜方法で製造されるフィルムを光学補償シートに利用する場合、フイルムそのものを光学補償シートとして用いることができる。なお、フイルムそのものを光学補償シートとして用いる場合は、偏光板の透過軸と、光学補償シートの遅相軸とを実質的に平行又は垂直になるように配置することが好ましい。このような偏光板と光学補償シートとの配置については、特開平１０−４８４２０号公報に記載がある。液晶表示装置は、二枚の電極基板の間に液晶を担持してなる液晶セル、その両側に配置された二枚の偏光板、及び該液晶セルと該偏光板との間に少なくとも一枚の光学補償シートを配置した構成を有している。
【００８５】
液晶セルの液晶層は、通常は、二枚の基板の間にスペーサーを挟み込んで形成した空間に液晶を封入して形成する。透明電極層は、導電性物質を含む透明な膜として基板上に形成する。液晶セルには、さらにガスバリアー層、ハードコート層あるいは（透明電極層の接着に用いる）アンダーコート層（下塗り層）を設けてもよい。これらの層は、通常、基板上に設けられる。液晶セルの基板は、一般に５０μｍ〜２ｍｍの厚さを有する。
【００８６】
光学補償シートは複屈折性を有し、液晶表示装置の表示画面の着色を取り除いたり、視野角特性を改善したりする目的で用いられる。本発明によるセルロースアシレートフィルムそのものを、光学補償シートとして用いることができる。さらに反射防止層、防眩性層、λ／４層や２軸延伸セルロースアシレートフィルムとして機能を付与してもよい。また、液晶表示装置の視野角を改良するため、本技術のセルロースアシレートフィルムと、それとは（正／負の関係が）逆の複屈折を示すフィルムを重ねて光学補償シートとして用いてもよい。
【００８７】
また、支持体の上に液晶性化合物（特にディスコティック液晶性分子）を含む光学的異方性層を設けた光学補償シートも提案されている（特開平３−９３２５号、同６−１４８４２９号、同８−５０２０６号、同９−２６５７２号の各公報記載）。本発明の溶液製膜方法で製造されるフィルムそのような光学補償シートの支持体としても用いることができる。
【００８８】
前記偏光板の偏光素子には、ヨウ素系偏光膜、二色性染料を用いる染料系偏光膜やポリエン系偏光膜がある。いずれの偏光素子も、一般にポリビニルアルコール系フィルムを用いて製造する。偏光板の保護膜は、２５〜３５０μｍの厚さを有することが好ましく、４０〜２００μｍの厚さを有することがさらに好ましい。液晶表示装置には、表面処理膜を設けてもよい。表面処理膜の機能には、ハードコート、防曇処理、防眩処理及び反射防止処理が含まれる。
【００８９】
前記光学的異方性層は、負の一軸性を有し傾斜配向したディスコティック液晶性分子を含む層であることが好ましい。ディスコティック液晶性分子を含む層が、円盤面と支持体面とのなす角が光学的異方性層の深さ方向において変化したハイブリッド配向していても構わないし、円盤面が支持体面と平行なホメオトロピック配向、円盤面が支持体面と垂直なホモジニアス配向、又は、円盤面が光学的異方性層の深さ方向でねじれているツイスト配向を取っていても構わない。また、これらの配向が混在した配向（例えば、ハイブリッド配向＋ツイスト配向）していても構わない。そのなかでもハイブリッド配向していることが好ましい。ディスコティック液晶性分子ひとつひとつの光軸は、円盤面の法線方向に存在する。しかし、ディスコティック液晶性分子がハイブリッド配向している層全体としては、光軸は存在しない。
【００９０】
本発明の溶液製膜方法により製造されるフィルムは、様々な表示モードの液晶セルに用いることができる。ＴＮ（Ｔｗｉｓｔｅｄ Ｎｅｍａｔｉｃ）、ＩＰＳ（Ｉｎ−Ｐｌａｎｅ Ｓｗｉｔｃｈｉｎｇ）、ＦＬＣ（Ｆｅｒｒｏｅｌｅｃｔｒｉｃ Ｌｉｑｕｉｄ Ｃｒｙｓｔａｌ）、ＡＦＬＣ（Ａｎｔｉ−ｆｅｒｒｏｅｌｅｃｔｒｉｃ Ｌｉｑｕｉｄ Ｃｒｙｓｔａｌ）、ＯＣＢ（Ｏｐｔｉｃａｌｌｙ Ｃｏｍｐｅｎｓａｔｏｒｙ Ｂｅｎｄ）、ＳＴＮ（Ｓｕｐｐｅｒ Ｔｗｉｓｔｅｄ Ｎｅｍａｔｉｃ）、ＶＡ（Ｖｅｒｔｉｃａｌｌｙ Ａｌｉｇｎｅｄ）及びＨＡＮ（Ｈｙｂｒｉｄ Ａｌｉｇｎｅｄ Ｎｅｍａｔｉｃ）のような様々な表示モードが提案されている。また、上記表示モードを配向分割した表示モードも提案されている。セルロースアシレートフィルムは、いずれの表示モードの液晶表示装置においても有効である。また、透過型、反射型、半透過型のいずれの液晶表示装置においても有効である。
【００９１】
本発明の溶液製膜方法で製造されるフィルムをＴＮモードの液晶セルを有するＴＮ型液晶表示装置の光学補償シートの支持体として用いてもよい。ＴＮモードの液晶セルとＴＮ型液晶表示装置については、古くから良く知られている。ＴＮ型液晶表示装置に用いる光学補償シートについては、特開平３−９３２５号、同６−１４８４２９号、同８−５０２０６号、同９−２６５７２号の各公報に記載がある。また、モリ（Ｍｏｒｉ）他の論文（Ｊｐｎ．Ｊ．Ａｐｐｌ．Ｐｈｙｓ．Ｖｏｌ．３６（１９９７）ｐ．１４３や、Ｊｐｎ．Ｊ．Ａｐｐｌ．Ｐｈｙｓ．Ｖｏｌ．３６（１９９７）ｐ．１０６８）に記載がある。ＴＮ型液晶表示装置については、特開平１０−１２３４７８号、ＷＯ９８４８３２０号、特許第３０２２４７７号の各公報に記載がある。
【００９２】
本発明の溶液製膜方法で製造されるフィルムをＳＴＮモードの液晶セルを有するＳＴＮ型液晶表示装置の光学補償シートの支持体として用いてもよい。一般的にＳＴＮ型液晶表示装置では、液晶セル中の棒状液晶性分子が９０〜３６０度の範囲にねじられており、棒状液晶性分子の屈折率異方性（Δｎ）とセルギャップ（ｄ）との積（Δｎｄ）が３００〜１５００ｎｍの範囲にある。ＳＴＮ型液晶表示装置に用いる光学補償シートについては、特開２０００−１０５３１６号公報に記載がある。
【００９３】
本発明の溶液製膜方法で製造されるフィルムをＶＡモードの液晶セルを有するＶＡ型液晶表示装置の光学補償シートの支持体として用いてもよい。ＶＡ型液晶表示装置に用いる光学補償シートには、レターデーションの絶対値が最小となる方向が光学補償シートの面内にも法線方向にも存在しないことが好ましい。ＶＡ型液晶表示装置に用いる光学補償シートの光学的性質は、光学的異方性層の光学的性質、支持体の光学的性質及び光学的異方性層と支持体との配置により決定される。ＶＡ型液晶表示装置に光学補償シートを二枚使用する場合は、光学補償シートの面内レターデーションを、−５ｎｍ〜５ｎｍの範囲内にすることが好ましい。従って、二枚の光学補償シートのそれぞれの面内レターデーションの絶対値は、０〜５とすることが好ましい。ＶＡ型液晶表示装置に光学補償シートを一枚使用する場合は、光学補償シートの面内レターデーションを、−１０ｎｍ〜１０ｎｍの範囲内にすることが好ましい。
【００９４】
本発明の溶液製膜方法で製造されるフィルムを、ＯＣＢモードの液晶セルを有するＯＣＢ型液晶表示装置あるいはＨＡＮモードの液晶セルを有するＨＡＮ型液晶表示装置の光学補償シートの支持体として用いてもよい。ＯＣＢ型液晶表示装置あるいはＨＡＮ型液晶表示装置に用いる光学補償シートには、レターデーションの絶対値が最小となる方向が光学補償シートの面内にも法線方向にも存在しないことが好ましい。ＯＣＢ型液晶表示装置あるいはＨＡＮ型液晶表示装置に用いる光学補償シートの光学的性質も、光学的異方性層の光学的性質、支持体の光学的性質及び光学的異方性層と支持体との配置により決定される。ＯＣＢ型液晶表示装置あるいはＨＡＮ型液晶表示装置に用いる光学補償シートについては、特開平９−１９７３９７号公報に記載がある。また、モリ（Ｍｏｒｉ）他の論文（Ｊｐｎ．Ｊ．Ａｐｐｌ．Ｐｈｙｓ．Ｖｏｌ．３８（１９９９）ｐ．２８３７）に記載がある。
【００９５】
本発明の溶液製膜方法で製造されるフィルムをＡＳＭ（Ａｘｉａｌｌｙ Ｓｙｍｍｅｔｒｉｃ Ａｌｉｇｎｅｄ Ｍｉｃｒｏｃｅｌｌ）モードの液晶セルを有するＡＳＭ型液晶表示装置の光学補償シートの支持体として用いてもよい。ＡＳＭモードの液晶セルは、セルの厚さが位置調整可能な樹脂スペーサーにより維持されているとの特徴がある。その他の性質は、ＴＮモードの液晶セルと同様である。ＡＳＭモードの液晶セルとＡＳＭ型液晶表示装置については、クメ（Ｋｕｍｅ）外の論文（Ｋｕｍｅ ｅｔ ａｌ．，ＳＩＤ ９８ Ｄｉｇｅｓｔ １０８９（１９９８））に記載がある。
【００９６】
本発明の溶液製膜方法を実施する溶液製膜装置の一実施形態を図面を参照して説明する。図１は溶液製膜装置の概略図、図２は溶液製膜装置の剥ぎ取り部分の拡大図である。
【００９７】
図１において、１はミキシングタンクで、セルローストリアセテート、添加剤及び溶媒を投入してドープを調製するものである。このミキシングタンク１は、送液ポンプ２及びフィルタ３を介して流延ダイ４に連結されている。そして、これらのミキシングタンク１、送液ポンプ２及びフィルタ３からなるドープの送液工程は、３層構成のフィルムを製造できるように３組設けられている。流延ダイ４の下方には、流延支持体としてのステンレススチール製の流延バンド５が配置されており、この流延バンド５は回転ドラム６、７に巻き掛けられており、また、回転ドラム６と回転ドラム７との間にはガイドロール８が複数設けられている。さらに、流延バンド５の上方及び下方には、流延バンド５上に流延されたドープに熱風を吹付けて乾燥させるための、乾燥風吹付け手段（図示せず）が設けられている。前記流延ダイ４側の回転ドラム６に隣接して剥ぎ取りロール９が設けられ、さらに多数のガイドロール１０及び巻取りロール１１が設けられ、剥ぎ取りロール９と巻取りロール１１間は乾燥部１２となっている。
【００９８】
以上のような溶液製膜装置で製膜するには、流延ダイ４からドープを吐出して流延バンド５に流延し、流延バンド５上で乾燥させつつ搬送する。流延バンド５上である程度乾燥したフィルムは、剥ぎ取りロール９で流延バンド５より剥ぎ取られる。この時、フィルムの剥ぎ取り角度を所定範囲に調整してある。この剥ぎ取り角度について図２を参照して説明する。
【００９９】
図２において、実線で示すフィルム１４は、剥離点ａにおいて流延バンド５から剥ぎ取られており、このとき、剥離点ａにおける接線方向ｈを０度、法線方向ｖを９０度としたとき、フィルム１４の剥ぎ取り角度（接線方向ｈとフィルムのなす角度）θは、３０〜８０度の範囲に設定されており、具体的には約７５度となっている。また、二点鎖線で示すフィルム１４の場合も同様に、剥離点ａ’における剥ぎ取り角度θ’が、接線方向ｈ’及び法線方向ｖ’において３０〜８０度の範囲に設定されており、具体的には約３１度となっている。また、流延バンド５の周速度Ｖ１、剥ぎ取りロール９の周速度Ｖ２とすると、（Ｖ２−Ｖ１）／Ｖ１＝０．００５〜１．０の範囲になるように設定されている。
【０１００】
さらに、流延バンド５の剥離点ａと剥ぎ取りロール９の接触点ｂとの距離をＬ、とすると、Ｌ／（Ｖ１＋Ｖ２）／２＝０．０３〜０．３秒の範囲に設定されている。
【０１０１】
本発明の溶液製膜方法で製造できるフィルムを図３及び図４を参照して説明する。図３及び図４は、フィルムを概略的に示す断面図である。
【０１０２】
図３に示すフィルム２１Ａは、一方の側の外表面２１ａの弾性率が内部２１ｂの弾性率よりも低くなるように形成されている。また、フィルム２１Ｂは、両側の外表面２１ａ、２１ｃの弾性率が内部２１ｂの弾性率より低くなるように形成されている。
【０１０３】
図４に示すフィルム２２Ａは二層構造を有し、一方の側の表面層２２ａの弾性率が内部２２ｂの弾性率よりも低くなるように形成されている。また、フィルム２２Ｂは三層構造を有し、両側の表面層２２ａ、２２ｃの弾性率が内部２２ｂの弾性率よりも低くなるように形成されている。
【０１０４】
なお、本発明は、これらの層構成に限定されるものでなく、例えば、四層以上の多層構造であってもよい。
【０１０５】
本発明の溶液製膜方法に利用することができる共流延法の例を図５〜図７を参照して説明する。
【０１０６】
図５はダイの概略断面図、図６はフィードブロックの概略断面図である。図５に示す共流延法は、共流延ダイ３０に図６に示すようなフィードブロック３１を設けたものを使用し、フィードブロック３１により共流延ダイ３０の手前で各ドープ３２を合流させた後、共流延ダイ３０よりドープ３２を矢印方向に一定速度で移動している支持体３３上に吐出させて同時に流延する方法である。
【０１０７】
図７は他の共流延法の例を示すダイの概略断面図である。図７に示す共流延法は、共流延ダイ４０が３個のマニホールド４１、４２、４３を有するマルチマニホールドダイで、共流延ダイ４０の内部でドープ４４を合流させた後、共流延ダイ４０からドープ４４を支持体４５条に吐出させて同時に流延する方法である。
【０１０８】
次に、本発明の溶液製膜方法に利用することができる逐次流延法について図８を参照して説明する。
【０１０９】
図８はダイの概略断面図である。図８に示す逐次流延法は、３個のダイ５０、６０、７０が支持体８０上に並べられ、各ダイ５０、６０、７０からそれぞれドープ５１、６１、７１を支持体８０上に流延するもので、この時、下流側にあるダイ６０は上流側にあるダイ５０が流延したドープ５１の上面にドープ６１を流延することになり、また、下流側にあるダイ７０は上流側にあるダイ６０が流延したドープ６１の上面にドープ７１を流延することになり、３層構成のフィルムを形成することができる。
【０１１０】
また、本発明の溶液製膜法に利用することができる溶液製膜装置の例を図９〜１８に示す。
【０１１１】
図９に示す溶液製膜装置は、流延支持体として流延バンドを用いたものである。図１０に示す溶液製膜装置は、流延支持体として流延バンドを用い、また、テンタ−を用いたものである。図１１に示す溶液製膜装置も、流延支持体として流延バンドを用い、また、テンタ−を用いたものである。図１２に示す溶液製膜装置も、流延支持体として流延バンドを用い、また、テンタ−を用いたものである。図１３に示す溶液製膜装置も、流延支持体として流延バンドを用い、また、テンタ−及び伝熱手段を用いたものである。図１４に示す溶液製膜装置も、流延支持体として流延バンドを用い、また、テンタ−及び伝熱手段を用いたものである。図１５に示す溶液製膜装置も、流延支持体として流延バンドを用い、また、テンタ−及び伝熱手段を用いたものである。図１６に示す溶液製膜装置は、流延支持体として冷却ドラムを用い、また、テンタ−を用いたものである。図１７に示す溶液製膜装置も、流延支持体として冷却ドラムを用い、また、テンタ−を用いたものである。図１８に示す溶液製膜装置は、流延支持体として乾燥ドラムを用い、また、テンタ−を用いたものである。
【０１１２】
なお、以上の溶液製膜装置において、８１はダイ、８２は流延支持体、８３は乾燥装置、８４はテンタ−である。
【０１１３】
【実施例】
［実施例１〜１２、１４、比較例１〜３］
図１に示す溶液製膜装置を用いて単層製膜を行なった。
【０１１４】
使用したドープの組成は以下の通りである。
セルローストリアセテート（酢化度６０．９％） ２０．４質量部
トリフェニルフォスフェート ３．１質量部
ジクロロメタン ６５．０質量部
ｎ−ブタノール ５．４質量部
メタノール ９．１質量部
【０１１５】
以上のドープを用い、剥ぎ取り角度、流延支持体の周速度Ｖ１、剥ぎ取りロープの周速度Ｖ２、流延支持体からの剥ぎ取り点と、剥ぎ取りロールに接する接触点までの距離Ｌ、残留溶媒量、縦弾性係数、厚み、耳端部最大厚み、表層厚み（２層構成の場合）を変化させてセルローストリアセテートフィルムを製造した。
【０１１６】
［実施１３］
図１に示す溶液製膜装置を用いて２層の重層製膜を行なった。
【０１１７】
使用したドープの組成は以下の通りである。
＜表面層（支持体面側）＞
セルローストリアセテート（酢化度６０．９％） ２０．４質量部
トリフェニルフォスフェート ３．１質量部
ジクロロメタン ６５．０質量部
ｎ−ブタノール ５．４質量部
メタノール ９．１質量部
クエン酸 ０．０３質量部
【０１１８】
＜コア層＞
セルローストリアセテート（酢化度６０．９％） ２０．４質量部
トリフェニルフォスフェート ３．１質量部
ジクロロメタン ６５．０質量部
ｎ−ブタノール ５．４質量部
メタノール ９．１質量部
【０１１９】
以上のドープを用い、共流延により２層からなるセルローストリアセテートフィルムを製造した。
【０１２０】
以上の実施例１〜１４及び比較例１〜３のムラ及びヘイズを評価した。評価結果を表１に示す。
【０１２１】
【表１】

【０１２２】
［ムラ評価］
フィルムを目視により観察し、評価した。評価内容は以下の通りである。
◎：ムラが視認できないレベル
○：ムラは視認できるが、ムラ限度より良いレベル
△：ムラ限度と同じレベル
×：ムラ限度より悪いレベル
【０１２３】
［透明度］
可視光６１５ｎｍの透過率を測定した。
【０１２４】
【発明の効果】
本発明は、以上のように構成することにより、流延支持体からフィルムを剥ぎ取る際、段ムラ及びベコ状ムラが発生することなく、平面性の良好なフィルムを製造することができる。
【図面の簡単な説明】
【図１】 本発明による溶液製膜方法を実施する溶液製膜装置の一実施形態の概略部である。
【図２】 本発明による溶液製膜方法を実施する溶液製膜装置の一実施形態の剥ぎ取り部分の拡大図である。
【図３】 本発明の溶液製膜方法で製造できるフィルムを概略的に示す断面図である。
【図４】 本発明の溶液製膜方法で製造できるフィルムを概略的に示す断面図である。
【図５】 本発明の溶液製膜方法に利用することができるダイの概略断面図である。
【図６】 本発明の溶液製膜方法に利用することができるフィードブロックの概略断面図である。
【図７】 本発明の溶液製膜方法に利用することができるダイの概略断面図である。
【図８】 本発明の溶液流延方法に利用することができるダイの概略断面図である。
【図９】 本発明の溶液製膜方法に利用することができる溶液製膜装置の概略図である。
【図１０】 本発明の溶液製膜方法に利用することができる溶液製膜装置の概略図である。
【図１１】 本発明の溶液製膜方法に利用することができる溶液製膜装置の概略図である。
【図１２】 本発明の溶液製膜方法に利用することができる溶液製膜装置の概略図である。
【図１３】 本発明の溶液製膜方法に利用することができる溶液製膜装置の概略図である。
【図１４】 本発明の溶液製膜方法に利用することができる溶液製膜装置の概略図である。
【図１５】 本発明の溶液製膜方法に利用することができる溶液製膜装置の概略図である。
【図１６】 本発明の溶液製膜方法に利用することができる溶液製膜装置の概略図である。
【図１７】 本発明の溶液製膜方法に利用することができる溶液製膜装置の概略図である。
【図１８】 本発明の溶液製膜方法に利用することができる溶液製膜装置の概略図である。
【符号の説明】
１…ミキシングタンク
２…送液ポンプ
３…フィルタ
４…流延ダイ
５…流延バンド
６、７…回転ドラム
８…ガイドロール
９…剥ぎ取りロール
１０…ガイドロール
１１…巻き取りロール
１２…乾燥部
１４…フィルム
ａ…剥離点
ｂ…接触点
ｈ…接線方向
ｖ…法線方向
θ…剥ぎ取り角度[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solution casting method capable of producing a film having good flatness.
[0002]
[Prior art]
Cellulose ester film has good transparency, high mechanical strength, and small dimensional variation with humidity change and heat (good dimensional stability), so it is widely used for photographic photosensitive materials, polarizing plate protective films, etc. It has been.
[0003]
Such a cellulose ester film is manufactured by a solution casting method. In this solution casting method, a dope in which a polymer is dissolved in an organic solvent is cast from a casting die onto a casting support, and the casting support is performed. The dope cast on the body is dried to some extent, then peeled off, and further dried to produce a film as a product.
[0004]
[Problems to be solved by the invention]
However, in such a solution casting method, when stripping the dried and solidified film from the casting support, depending on the stripping conditions, step unevenness (waved unevenness generated in the longitudinal direction of the film), band streak ( Wavy unevenness that occurs in the width direction), unevenness in flatness of the film, and haze-up due to fine surface roughness, etc. may occur. Especially, the film forming speed is increased or the casting support is used. This occurred frequently when the speed was reduced due to excessive drying.
[0005]
An object of the present invention is to solve the above problems and to provide a solution casting method capable of producing a film having excellent flatness and excellent transparency.
[0006]
[Means for Solving the Problems]
The present inventor has intensively studied to achieve the above object, and found that the film peeling angle is related to the flatness of the film when the film is peeled off from the casting support. And when further researching and adjusting the peeling angle of this film within a predetermined range, it was found that step unevenness and the like did not occur, and the present invention was completed.
[0007]
Further, when the relationship between the separation point from the casting support and the contact point to the peeling roll and the film forming speed is in a specific range, it is found that step unevenness does not occur, and the present invention It has been completed.
[0008]
Further, when the relationship between the peripheral speed of the casting support and the stripping roll, the film tension, the film width, the film cross-sectional area, etc. is in a specific range, it was found that step unevenness does not occur and the present invention was completed. Is.
[0009]
  The solution casting method according to the present invention comprises a polymer, a solvent, and a solvent from a casting die to a casting support.BizoCasting a dope comprising an additive, drying the cast dope to some extent to form a film, peeling the film from the casting support with a roll, and further drying to produce a film. In the membrane method, at the peeling point of the casting support of the film peeled off from the casting supportIn the direction of travel of the filmWhen the tangential direction is 0 degree and the normal direction is 90 degrees, the film peeling angle is in the range of 30 to 80 degrees.At the same time, when the peripheral speed of the casting support is V1, and the peripheral speed of the peeling roll is V2, (V2-V1) / V1 is set in the range of 0.005 to 1.0.It is configured as a feature.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, when the tangential direction at the peeling point of the casting support of the film peeled off from the casting support is 0 degree and the normal direction is 90 degrees, the peeling angle of the film is 30 to 80 degrees. The range is preferably 50 to 70 degrees. When the peeling angle is less than 30 degrees, vibration due to shock at the time of peeling occurs in the film, and flatness changes such as scratches and unevenness due to contact with the casting support occur. In addition, gas stagnation is likely to occur at the stripping point, and film flattening due to gas condensation is also likely to occur. On the other hand, if the peeling angle exceeds 80 degrees, the film curvature at the peeling point increases, and unevenness or the like occurs. Further, the vertical movement of the stripping point due to the shock tends to be large, and uneven beveling tends to occur.
[0013]
In the present invention, the film peeling angle is set to 30 to 80 degrees. This stripping angle is related to the tension of the film from the casting support to the stripping roll, and if the film tension is increased, the film moves down, resulting in a smaller stripping angle and vice versa. If the tension of the film is lowered, the film moves upward, and as a result, the peeling angle increases. In addition, the peelability between the film and the casting support is also related. If the peelability is good, the peel angle is small, and if the peelability is bad, the peel angle is large. Therefore, the film peeling angle can be adjusted to a range of 30 to 80 degrees by controlling the tension of the film within a predetermined range or adjusting the peelability of the film.
[0014]
The film tension f is represented by the film strain (elongated length per unit length) ε between the casting support and the peeling roll and the film longitudinal elastic modulus E, and f = E * ε It becomes. Therefore, the stripping angle can be adjusted as a result by controlling the longitudinal elastic modulus E and the strain ε.
[0015]
The strain ε of the film can be controlled by the peripheral speed of the casting support and the peripheral speed of the peeling roll. When the peripheral speed of the casting support is V1, and the peripheral speed of the peeling roll is V2, , (V2−V1) /V1=0.005 to 1.0 is preferable, and (V2−V1) /V1=0.01 to 0.5 is more preferable.
[0016]
In addition, the solution casting method of the present invention is such that the distance between the peeling point from the casting support and the contact point in contact with the peeling roll is L, the circumferential speed of the casting support is V1, and the circumferential speed of the peeling roll. Is V2, L / {(V1 + V2) / 2} is set within 0.3 seconds, preferably within 0.2 seconds. When L / {(V1 + V2) / 2} exceeds 0.3 seconds, shrinkage in the width direction becomes large, wrinkles are easily generated on the roller, and band streaks (wave-like unevenness generated in the width direction) become strong.
[0017]
Furthermore, in the solution casting method of the present invention, at the peeling point of the casting support, the circumferential speed of the casting support is V1, the circumferential speed of the peeling roll is V2, and (V2-V1) / V1 is 0.00. When 001, the film tension immediately after peeling is F (kg), the film average width between peeling rolls from the peeling point is W (mm), the film average thickness is S (mm), and E = F / (S × E = 0.01-7 (kgf / mm) where W × 0.001)²), Preferably 0.05-2 (kgf / mm²). If E is less than 0.01, it becomes difficult to control the stripping angle to 80 degrees or less. Moreover, when E exceeds 7, it becomes difficult to control the peeling angle to 30 degrees or more.
[0018]
In the present invention, if the solid content of the film is P, the weight of the solvent amount is Q, and the residual solvent amount of the film is R = Q / P × 100 (wt%), the residual solvent amount R It is preferable to control E.
[0019]
In the present invention, the E is preferably controlled in the range of the casting support temperature at the peeling point of −30 to 60 ° C. When the casting support temperature is lower than −30 ° C., the degree of cooling and gelation of the film-like material composed of the polymer solution at the time of peeling proceeds, and it becomes difficult to control E to 7 or less. On the other hand, when the temperature is higher than 60 ° C., softening due to high temperature proceeds, and it becomes difficult to control E to 0.01 or more.
[0020]
In this invention, it is preferable to quantify the film tension between the peeling rolls from the peeling point of the casting support by the peeling roll shaft torque value and the tension meter value.
[0021]
In the present invention, at the peeling point where the film is peeled off from the casting support, the weight of the solid content of the film is P, the weight of the solvent amount is Q, and the residual solvent amount of the film is R = Q / P × Assuming 100 (wt%), the residual solvent amount R is preferably 120 wt% or more, and more preferably 200 wt% or more. If the residual solvent amount R is less than 120 wt%, it becomes difficult to control E to 7 or less, and the probability that the peel resistance will be 100 gf or more per 1 cm of film is increased.
[0022]
In the present invention, at the peeling point where the film is peeled off from the casting support, when the force in the normal direction of the casting support surface necessary for peeling is defined as the peeling resistance force, the peeling resistance force per 1 cm of the film It is preferably less than 100 gf, more preferably less than 50 gf. When the peeling resistance exceeds 100 gf per 1 cm, when the film peels, fine uneven deformation occurs on the film peeling surface side, and the flatness and transparency are deteriorated. Moreover, when it becomes larger, the peeling angle becomes 80 degrees or more, and further, the film is cut off from the remaining film.
[0023]
In the present invention, at the peeling point where the film is peeled off from the casting support, when the maximum thickness in the film width direction end is X and the average film thickness in the product range is Y in terms of thickness after drying, Y is 20 to It is within the range of 300 μm, the accuracy is within ± 3%, and the thickness ratio Z = X / Y is preferably 0.5 <Z <2.0, and 0.8 <Z <1.5. It is more preferable. When Z is 0.5 or less, the film ear end portion is thin, and therefore, the fluctuation in the peeling angle of the film ear end portion at the peeling point becomes large, and the film flatness within the product range is deteriorated due to the influence. Further, when Z is 2.0 or more, the film ear end portion is thick, so that the difference in the peeling angle with respect to the film product portion at the peeling point is large, and uneven stretching in the subsequent process is increased.
[0024]
In the present invention, the clearance CL between the casting support and the peeling roll is preferably in the range of 1 to 30 mm, more preferably in the range of 10 to 25 mm. If the clearance is less than 1 mm, the film transport space near the stripping point becomes small, so that gas stagnation is likely to occur and a surface failure due to gas condensation occurs. Moreover, since the length of L will become long easily when it exceeds 30 mm, a film tends to vibrate between stripping rolls from the stripping point, resulting in poor flatness.
[0025]
In this invention, the peeling roll radius R is 30 mm or more, The roll surface temperature shall be -20-80 degreeC, Preferably it shall be -10-50 degreeC. When the surface temperature is less than −20 ° C., gas dew condensation is likely to occur, and surface defects are likely to occur. Moreover, since it will become high with respect to film temperature when it exceeds 80 degreeC, since it becomes easy for a film to closely_contact | adhere to foaming and a roll surface in a film, a fine uneven | corrugated shape unevenness will generate | occur | produce.
[0026]
In the present invention, it is preferable to use a mirror-like stainless steel band having no pinhole with a maximum outer diameter of 30 μm or more as the casting support. By eliminating the pinholes having a maximum outer diameter of 30 μm or more, it is possible to produce an extremely smooth film without irregularities within the allowable range as a product.
[0027]
In the present invention, a drum having a diameter of 1.5 to 5.0 m having a mirror surface of nickel chrome plating without any pinhole having a maximum outer diameter of 30 μm or more is used as a casting support, and a jacket provided on the drum is − It is preferable to control the drum surface temperature by continuously passing a heat medium of 40 to 70 ° C.
[0028]
In the present invention, infrared rays are transmitted through the film immediately after being peeled off from the casting support, and the residual solvent amount of the film is measured in a non-contact manner from the change in the spectral absorption distribution. It is preferable to adjust the drying conditions in the upstream process so that the amount becomes the same.
[0029]
The solution film-forming method according to the present invention may be a single-layer film formation or a multi-layer film formation of two or more layers. When a multi-layer film formation is performed, the solution is formed on a layer in contact with the casting support. It is preferable to add an additive (hereinafter referred to as “peeling resistance reducing agent”) that reduces the peeling resistance with the support. The peeling angle can be adjusted by adding a peeling resistance reducing agent.
[0030]
As the peeling resistance reducing agent, a surfactant is effective, and is not particularly limited, such as a phosphoric acid type, a sulfonic acid type, a carboxylic acid type, a nonionic type, and a cationic type. These are described in, for example, JP-A-61-243837.
[0031]
These peeling resistance reducing agents are specifically described below. That is, before casting the cellulose acylate solution, 0.005 to 2% by mass of the solution of at least one peeling resistance reducing agent represented by the general formula (1) or the general formula (2) is added. To do.
General formula (1): (R₁-B₁-O)_n1-P (= O)-(OM₁)_n2
General formula (2): R₂-B₂-X
[0032]
Where R₁And R₂Represents a substituted, unsubstituted alkyl group, alkenyl group, aralkyl group or allyl group having 4 to 40 carbon atoms;₁Are alkali metals, ammonia, and lower alkylamines. B₁, B₂Represents a divalent linking group, and X represents a carboxylic acid (or a salt thereof), a sulfonic acid (or a salt thereof), or a sulfate ester (or a salt thereof). n1 is an integer of 1 and 2, and n2 represents an integer of (3-n1).
[0033]
In the present invention, it is preferable that the cellulose hiscylate film contains at least one peeling resistance reducing agent represented by the general formula (1) or (2). These peeling resistance reducing agents are described below.
[0034]
R₁And R₂Preferred examples of the alkyl group include substituted or unsubstituted alkyl groups having 4 to 40 carbon atoms (for example, butyl, hexyl, octyl, 2-ethylhexyl, nonyl, dodecyl, hexadecyl, octadecyl, eicosanyl, docosanyl, myricyl, etc.), carbon number 4- to 40-substituted, unsubstituted alkenyl groups (eg, 2-hexenyl, 9-decenyl, oleyl, etc.), C4-C40 substituted, unsubstituted allyl groups (eg, phenyl, naphthyl, methylphenyl, dimethyl) Phenyl, trimethylphenyl, ethylphenyl, propylphenyl, diisopropylphenyl, triisopropylphenyl, t-butylphenyl, di-t-butylphenyl, tri-t-butylphenyl, isopentylphenyl, octylphenyl, isooctylphenyl, isononyl Phenyl, di Seo nonylphenyl, dodecylphenyl, isopropylene pentadecylphenyl) represents the like.
[0035]
Of these, hexyl, octyl, 2-ethylhexyl, nonyl, dodecyl, hexadecyl, octadecyl, docosanyl, alkenyl as alkenyl, phenyl, naphthyl, trimethylphenyl, diisopropylphenyl, triisopropyl as an allyl group are more preferable. Phenyl, di-t-butylphenyl, tri-t-butylphenyl, isooctylphenyl, isononylphenyl, diisononylphenyl, dodecylsulfopentadecylphenyl.
[0036]
Next, B₁, B₂The divalent linking group is described. These are alkylene having 1 to 10 carbon atoms, poly (degree of polymerization 1 to 50) oxyethylene, poly (degree of polymerization 1 to 50) oxypropylene, poly (degree of polymerization 1 to 50) oxyglycerin, and a mixture thereof. . Preferred linking groups among these are methylene, ethylene, propylene, butylene, poly (degree of polymerization 1-25) oxyethylene, poly (degree of polymerization 1-25) oxypropylene, and poly (degree of polymerization 1-15) oxyglycerin. Next, X is carboxylic acid (or salt), sulfonic acid (or salt), sulfate ester (or salt), particularly preferably sulfonic acid (or salt) or sulfate ester (or salt). Preferred salts are Na, K, ammonium, trimethylamine and triethanolamine.
[0037]
Specific examples of the preferred peeling resistance reducing agent of the present invention are described below, but are not limited thereto.
RZ-1: C₈H₁₇O-P (= O)-(OH)₂
RZ-2: C₁₂H_{twenty five}O-P (= O)-(OK)₂
RZ-3: C₁₂H_{twenty five}OCH₂CH₂O-P (= O)-(OK)₂
RZ-4: C₁₅H₃₁(OCH₂CH₂)_FiveO-P (= O)-(OK)₂
RZ-5: {C₁₂H_{twenty five}O (CH₂CH₂O)_Five}₂-P (= O) -OH
RZ-6: {C₁₈H₃₅(OCH₂CH₂)₈O}₂-P (= O) ONH_Four
RZ-7: (t-C_FourH₉)_Three-C₆H₂-OCH₂CH₂O-P (= O)-(OK)₂
RZ-8: (iso-C₉H₁₉-C₆H_Four-O- (CH₂CH₂O)_Five-P (= O)-(OK) (OH)
RZ-9: C₁₂H_{twenty five}SO_ThreeNa
RZ-10: C₁₂H_{twenty five}OSO_ThreeNa
RZ-11: C₁₇H₃₃COOH
RZ-12: C₁₇H₃₃COOH N (CH₂CH₂OH)_Three
RZ-13: iso-C₈H₁₇-C₆H_Four-O- (CH₂CH₂O)_Three-(CH₂)₂SO_ThreeNa
RZ-14: (iso-C₉H₁₉)₂-C₆H_Three-O- (CH₂CH₂O)_Three-(CH₂)_FourSO_ThreeNa
RZ-15: Sodium triisopropyl naphthalene sulfonate
RZ-16: Sodium tri-t-butylnaphthalene sulfonate
RZ-17: C₁₇H₃₃CON (CH_Three) CH₂CH₂SO_ThreeNa
RZ-18: C₁₂H_{twenty five}-C₆H_FourSO_Three・ NH_Four
[0038]
The amount of at least one of the general formula (1) or (2) used in the present invention is 0.002 to 2% by mass of the solution, more preferably 0.005 to 1% by mass, and still more preferably 0. 0.01 to 0.5% by mass. Although the addition method is not particularly limited, it may be added together with other materials before dissolving as a liquid or solid as it is, or may be added to a cellulose acylate solution prepared in advance.
[0039]
Furthermore, the acid dissociation index pKa 1.93 to 4.50 described in JP-A-10-316701 (preferably 2.0 to 4.4, more preferably 2.2 to 4.3 (for example, 2.5 to 4.0), particularly 2.6 to 4.3 (for example, about 2.6 to 4.0)} acid or a salt thereof is preferable. This may be either an inorganic acid or an organic acid. For the pKa of acids, you can refer to “Revised 3rd edition, Chemical Handbook, Fundamentals II” (edited by The Chemical Society of Japan, published by Maruzen Co., Ltd.). The acid dissociation index pKa is shown below in parentheses together with specific examples of acids.
[0040]
Examples of the inorganic acid include HClO.₂(2.31), HOCH (3.48), molybdic acid (H₂, MoO_Four: 3.62), HNO₂(3.15), phosphoric acid (H_Three, PO_Four: 2.15), tripolyphosphoric acid (H_Five, P_Three, O_Ten: 2.0), panadic acid (H_Three, VO_Four: 3.78). Examples of organic acids include formic acid (3.55), oxaloacetic acid (2.27), cyanoacetic acid (2.47), phenylacetic acid (4.10), and phenoxyacetic acid (2.99) as aliphatic monocarboxylic acids. , Substitution of fluoroacetic acid (2.59), chloroacetic acid (2.68), bromoacetic acid (2.72), iodoacetic acid (2.98), mercaptoacetic acid (3.43) vinylacetic acid (4.12), etc. Examples thereof include acetic acid having a group, halopropionic acid such as chloropropionic acid (2.71 to 3.92), 4-aminobutyric acid (4.03), and acrylic acid (4.26). Examples of the aliphatic polycarboxylic acid include malonic acid (2.65), succinic acid (4.00), glutaric acid (4.13), adipic acid (4.26), pimelic acid (4.31), Azelaic acid (4.39), fumaric acid (2.85), etc., glycolic acid (3.63), lactic acid (3.66), malic acid (3.24), tartaric acid (2) as oxycarboxylic acid .82-2.99), citric acid (2.87) and the like. Furthermore, aniline sulfonic acid (3.74-3) which is an aromatic monocarboxylic acid such as glyoxylic acid (3.18), pyruvic acid (2.26), levulinic acid (4.44) as aldehyde acid or ketone acid. .23), benzoic acid (4.20), aminobenzoic acid (2.02 to 3.12), chlorobenzoic acid (2.92 to 3.99), cyanobenzoic acid (3.60 to 3.55) , Nitrobenzoic acid (2.17 to 3.45), hydroxybenzoic acid (4.08 to 4.58), anisic acid (4.09 to 4.48), fluorobenzoic acid (3.27 to 4.14) ), Benzoic acid having a substituent such as chlorobenzoic acid, bromobenzoic acid (2.85 to 4.00), iodobenzoic acid (2.86 to 4.00), salicylic acid (2.81), naphthoic acid ( 3.70-4.16), cinnamic acid (3 88), and also such as mandelic acid (3.19). Moreover, nicotinic acid (2.05) of a heterocyclic monocarboxylic acid such as phthalic acid (2.75), isophthalic acid (3.50), and terephthalic acid (3.54), which are aromatic polyvalent carboxylic acids, Also included are heterocyclic polyvalent carboxylic acids such as 2-furancarboxylic acid (2.97), 2,6-pyridinecarboxylic acid (2.09), and the like.
[0041]
Furthermore, amino acids may be used as the organic acid. For example, asparagine (2.14), aspartic acid (1.93), adenine (4.07), alanine (2.30), β-alanine (3 .53), arginine (2.05), isoleucine (2.32), glycine (2.36), glutamine (2.17), glutamic acid (2.18), serine (2.13), tyrosine (2. 17), tryptophan (2.35), threonine (2.21), norleucine (2.30), valine (2.26), phenylalanine (2.26), methionine (2.15), lysine (2.04) ), And leucine (2.35), such as adenosine (3.50), adenosine triphosphate (4.06), adenosine phosphate (3.65 to 3.80), which are amino acid derivatives, -Alanyl-L-alanine (3.20), L-alanylglycine (3.10), β-alanylglycine (3.18), L-alanylglycylglycine (3.24), β-alanylglycine Sylglycine (3.19), L-alanylglycylglycylglycine (3.18), glycyl-L-alanine (3.07), glycyl-β-alanine (3.91), glycylglycyl-L-alanine ( 3.18), glycylglycylglycine (3.20), glycylglycylglycylglycine (3.18), glycylglycyl-L-histidine (2.72), glycylglycylglycyl-L-histidine (2. 90), glycyl-DL-histidylglycine (3.26), glycyl-L-histidine (2.54), glycyl-L-leucine (3.09), γ-L Glutamine-L-cysteinylglycine (2.03), N-methylglycine (sarcosine: 2.20), N, N-dimethylglycine (2.08), citrulline (2.43), 3,4-dihydroxy Phenylalanine (2.31), L-histidylglycine (2.84), L-phenylalanylglycine (3.02), L-prolylglycine (3.07), L-leucyl-L-tyrosine ( 3.15) is used.
[0042]
In the present invention, among the above acids, aliphatic monocarboxylic acids such as formic acid, haloacetic acids such as chloroacetic acid, saturated or unsaturated C such as halopropionic acid and acrylic acid.₁~₃Saturated or unsaturated C such as monocarboxylic acid, aliphatic polycarboxylic acid such as malonic acid, succinic acid, glutaric acid, fumaric acid₂~₄Dicarboxylic acids and other oxycarboxylic acids such as glycolic acid, lactic acid, malic acid, tartaric acid and citric acid₁~₆Oxycarboxylic acids are preferred. These acids may be water-insoluble or water-soluble.
[0043]
The aforementioned acid may be used as a free acid, or may be used as an alkali metal salt, alkaline earth metal salt, or heavy metal. Examples of the alkali metal include lithium, potassium, and sodium, and examples of the alkaline earth metal include calcium, magnesium, barium, and strontium. Examples of heavy metals include zinc, tin, nickel, and iron.
[0044]
Preferred alkali metals include sodium, and preferred alkaline earth metals include calcium and magnesium. These alkali metals and alkaline earth metals can be used alone or in combination of two or more thereof, and alkali metals and alkaline earth metals may be used in combination.
[0045]
The total content of the acid and the metal salt thereof is within a range that does not impair peelability, transparency, spinnability, etc., for example, 1 × 10 per 1 g of cellulose acylate.^-9~ 3x10^-FiveMoles, preferably 1 × 10^-8~ 2x10^-FiveMole (eg 5 × 10^-7~ 1.5 × 10^-FiveMol), more preferably 1 × 10^-7~ 1x10^-FiveMole (eg 5 × 10^-6~ 8x10^-6Mol)), usually 5 × 10^-7~ 5x10^-6Moles (eg 6 × 10^-7~ 3x10^-6Mole).
[0046]
In addition, content of the said acid and its metal salt in a cellulose acylate can be quantified with the following method.
[0047]
[Ion chromatography analysis]
Weigh accurately 2.0 g of dry cellulose acetate in the form of fine powder, add 80 ml of hot water, stir, seal and let stand overnight, then stir further to allow the sample to settle. About 10 ml of the supernatant is used as a sample solution, and the acid content is measured by ion chromatography.
[0048]
In addition, these alkali metals and / or alkaline earth metals may be combined with an acidic group (such as a carboxyl group or a sulfonic acid group) of cellulose acetate when the content is small. The total content of alkali metal and alkaline earth metal in 1 g of cellulose acetate is not less than an effective amount that does not impair the heat resistance stability of cellulose acetate, and is 5.5 × 10 in terms of ion equivalent.^-6Equivalent or less (for example, 0.01 × 10^-6~ 5x10^-6Equivalent), preferably 3.5 × 10^-6Equivalent or less (for example, 0.01 × 10^-6~ 3x10^-6Equivalent), more preferably 2.5 × 10^-6Equivalent or less (for example, 0.01 × 10^-6~ 2x10^-6Equivalent). In particular, the total content of alkali metals and alkaline earth metals is 1 × 10^-6Below equivalent (for example, 0.1 × 10^-6~ 0.5x10^-6Equivalent), in particular 0.3 × 10^-6Below equivalent (for example, 0.1 × 10^-6~ 0.3 × 10^-6When cellulose acetate having an equivalent weight) is used, when the dope is cast on the support by the casting method and the semi-dried film is peeled from the support, the peel resistance can be greatly reduced. The content of alkali metal and alkaline earth metal in cellulose acetate can be quantified by atomic absorption analysis.
[0049]
The cellulose acetates of the embodiments (1) and (2) can be obtained by, for example, mixing cellulose acetate and an acid having the acid dissociation index pKa or a metal salt thereof, or treating cellulose acetate with the acid or a metal salt thereof. Can be adjusted. The mixing or treatment of the acid or its metal salt is carried out after any process, for example, a process for producing cellulose acetate (for example, a process for adding a heat stabilizer after completion of the hydrolysis / ripening process) or the production of cellulose acetate. Can do. Moreover, you may perform the process by an acid or its metal salt by washing | cleaning, a dipping process, an impregnation process, etc. of a granular form and flake shaped cellulose acetate. Further, the mixing and treatment may be performed by adding an acid or a metal salt thereof to a dope containing cellulose acetate. The mixing or treatment of the acid having the acid dissociation index pKa or a metal salt thereof can be performed at an appropriate temperature that does not impair workability, for example, a temperature of about 10 to 70 ° C. (preferably 15 to 50 ° C.). The mixing or processing time can be selected from an appropriate range, for example, a range of about 1 minute to 12 hours. When such a specific pKa acid or metal salt thereof is used, at least a part of the carboxyl groups bonded to cellulose acetate and / or hemicellulose acetate can be present as an acid-type carboxyl group.
[0050]
After the cellulose acylate solution is cast, it is preferable that the residual solvent is peeled off from the support at 20 to 1000% by mass. Generally, when there is no stripping agent, the cellulose acylate solution is peeled off unless it is 20 to 150% by mass. It is difficult and takes time to dry. On the other hand, the cellulose acylate solution containing the peeling resistance reducing agent of the present technology can be stripped even if the residual solvent is 20 to 500% by mass, shortening the drying time, and greatly improving the productivity. It is possible. Furthermore, by including the peeling resistance reducing agent of the present technology, the peeling load at the time of peeling can be remarkably reduced, and thereby the surface shape is remarkably improved.
[0051]
Such a cellulose acetate film has high releasability from the support in the production of a film by a casting method, and can improve the film-forming speed and thus the productivity of the cellulose acetate film. Cellulose acetate is excellent in optical properties such as transparency. The transparency of cellulose acetate is, for example, about 60 to 100% (preferably 70 to 100%, more preferably 75 to 100%), usually about 70 to 90%, and haze is 1 to 8 (preferably 1 to 1). 5) About. Furthermore, the yellowness index (Yellowness Index, YI) used as the yellowness index of cellulose acetate is, for example, about 1 to 10 (preferably 1 to 7, usually 2 to 5). The transparency, haze, and yellowness index (YI) are values measured by the following method.
[0052]
The amount of the peeling resistance reducing agent added is preferably 0.002 to 2% by mass, more preferably 0.01 to 0.5% by mass with respect to the dope weight.
[0053]
The solution film-forming method of the present invention can be used for film formation of a cellulose ester film or the like. Examples of the cellulose ester include lower fatty acid esters of cellulose (eg, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate). Is representative. Lower fatty acid means a fatty acid having 6 or less carbon atoms. Cellulose acetate includes cellulose triacetate (TAC) and cellulose diacetate (DAC).
[0054]
As the solvent used for the dope, a lower aliphatic hydrocarbon chloride or a lower aliphatic alcohol is generally used. An example of a lower aliphatic hydrocarbon chloride is methylene chloride. Examples of lower aliphatic alcohols include methanol, ethanol, n-propyl alcohol, isopropyl alcohol and n-butanol. Examples of other solvents are substantially free of halogenated hydrocarbons, acetone, ketones having 4 to 12 carbon atoms include, for example, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone, Examples of the ester having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate, 2-ethoxy-ethyl acetate and the like. Examples of the alcohol of formula 1 to 6 include methanol, ethanol, propanol, iso-propanol, 1-butanol, t-butanol, 2-methyl-2-butanol, 2-methoxyethanol, 2-butoxyethanol and the like. , Carbon atoms Examples of the ether having 3 to 12 include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole, and the number of carbon atoms is from 5 to 8. Such cyclic hydrocarbons include cyclopentane, cyclohexane, cycloheptane, cyclooctane and the like. In the present invention, it is preferable to use a solvent selected from methylene chloride, acetone, methyl acetate and dioxolane or a mixture thereof as the main solvent among the above solvents.
[0055]
Moreover, it is preferable to use the solvent which consists of methyl acetate, ketones, and alcohol and whose solvent ratio is 20-90 mass% of methyl acetate, 5-60 mass% of ketones, and 5-30 mass% of alcohol.
[0056]
The dope used in the solution casting method of the present invention includes various additives (for example, plasticizers, ultraviolet absorbers, deterioration inhibitors, fine particle powders, optical property modifiers, fluorine-based additives) according to the use in each preparation step. Surfactants) can be added. Further, the addition may be performed at any time in the dope preparation process, but may be performed by adding an additive to the final preparation process of the dope preparation process.
[0057]
The plasticizer that can be used in the present invention is not particularly limited, but in the phosphate ester type, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl Phosphate, etc., for phthalate esters, diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, etc., for glycolate esters, triacetin, tributyrin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl Ethyl glycolate, butyl phthalyl butyl glycolate and the like are preferably used alone or in combination.
[0058]
Further, plasticizers described in JP-A-11-80381, JP-A-11-124445, and JP-A-11-248940 can also be added.
The above plasticizers may be used alone or in combination of two or more. 0.1-20 mass% is preferable with respect to a cellulose ester, and, as for the addition amount of a plasticizer, 5-15 mass% is more preferable. When the addition amount is less than 0.1% by mass, the effect of addition cannot be sufficiently exhibited, and when the addition amount exceeds 20% by mass, the film surface may bleed out.
[0059]
The ultraviolet absorber can be selected from any type according to the purpose, and a salicylic acid ester-based, benzophenone-based, benzotriazole-based, benzoate-based, cyanoacrylate-based, nickel complex-based absorber or the like is used. However, benzophenone series, benzotriazole series, and salicylic acid ester series are preferred. Examples of benzophenone ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-acetoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4-methoxybenzophenone, 2, 2′-di-hydroxy-4,4′-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4- (2-hydroxy-3- And methacryloxy) propoxybenzophenone. As a benzotriazole ultraviolet absorber, 2 (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2 (2′-hydroxy-5′-tert-butylphenyl) ) Benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5 And chlorobenzotriazole, 2 (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, and the like. Examples of salicylic acid esters include phenyl salicylate, p-octylphenyl salicylate, and p-tert-butylphenyl salicylate. Among these exemplified ultraviolet absorbers, in particular, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4,4′-methoxybenzophenone, 2 (2′-hydroxy-3′-tert-butyl- 5'-methylphenyl) -5-chlorobenzotriazole, 2 (2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2 (2'-hydroxy-3 ', 5'-di-tert-amylphenyl) ) Benzotriazole, 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole is particularly preferred.
[0060]
As the ultraviolet absorber, it is preferable to use a combination of a plurality of absorbers having different absorption wavelengths because a high blocking effect can be obtained in a wide wavelength range. From the viewpoint of preventing deterioration of the liquid crystal, the ultraviolet absorbent for liquid crystal is preferably excellent in the ability to absorb ultraviolet rays having a wavelength of 370 nm or less, and from the viewpoint of liquid crystal display properties, the absorption of visible light having a wavelength of 400 nm or more is small. Examples include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. Particularly preferred ultraviolet absorbers are benzotriazole compounds and benzophenone compounds. Among these, a benzotriazole-based compound is preferable because unnecessary coloring with respect to the cellulose ester is small.
[0061]
As for the UV absorber, JP-A-60-235852, JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, JP-A-6-107854, JP-A-6-107854. 118233, 6-148430, 7-11056, 7-11055, 7-11056, 8-29619, 8-239509, JP-A-2000-204173 There is.
[0062]
0.001-5 mass% is preferable with respect to a cellulose acylate, and, as for the addition amount of a ultraviolet absorber, 0.01-1 mass% is more preferable. If the addition amount is less than 0.001% by mass, the effect of addition cannot be sufficiently exhibited. If the addition amount exceeds 5% by mass, the ultraviolet absorber may bleed out to the film surface.
[0063]
Further, the ultraviolet absorber may be added simultaneously with the dissolution of cellulose acylate, or may be added to the dope after dissolution. In particular, a mode in which an ultraviolet absorbent solution is added to the dope immediately before casting using a static mixer or the like is preferable because spectral absorption characteristics can be easily adjusted.
[0064]
The deterioration inhibitor can prevent cellulose triacetate and the like from deteriorating and decomposing. Examples of the deterioration preventing agent include butylamine, hindered amine compounds (JP-A-8-325537), guanidine compounds (JP-A-5-271471), benzotriazole-based UV absorbers (JP-A-6-235819), and benzophenone-based compounds. There are compounds such as UV absorbers (JP-A-6-118233).
[0065]
Among these, examples of hindered amine compounds include t-butylamine, triphenylamine, and tribenzylamine. Examples of guanidine derivatives include compounds represented by the following formulas (1a) and (1b).
[0066]
[Chemical 1]

[0067]
The addition amount of the deterioration preventing agent is preferably 0.001 to 5%, more preferably 0.01 to 1%. If the addition amount is less than 0.001%, the effect of addition is small, and if the addition amount exceeds 5%, the raw material cost increases, which is disadvantageous.
[0068]
As the fine particle powder, silica, kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, titanium oxide, alumina and the like can be arbitrarily used depending on the purpose. These fine particle powders are preferably dispersed in the binder solution by any means such as a high-speed mixer, a ball mill, an attritor, or an ultrasonic disperser before being added to the dope. As the binder, cellulose acylate is preferable. It is also preferable to carry out dispersion together with other additives such as ultraviolet absorbers. The dispersion solvent is arbitrary, but a composition close to that of the dope solvent is preferable.
[0069]
The number average particle size of the fine particle powder is preferably from 0.01 to 100 μm, particularly preferably from 0.1 to 10 μm. The dispersion may be added to the cellulose acylate dissolving step at the same time, or may be added to the dope at any step. However, a form of addition just before casting using a static mixer or the like is preferable as in the case of the ultraviolet absorber.
[0070]
The content of the fine particle powder is preferably 0.001 to 5% by mass, and more preferably 0.01 to 1% by mass with respect to the cellulose acylate. If the addition amount is less than 0.001% by mass, the effect of addition cannot be exhibited sufficiently, and if the addition amount exceeds 5% by mass, the appearance surface may be deteriorated.
[0071]
As the mold release agent, a surfactant is effective, and is not particularly limited, such as a phosphoric acid type, a sulfonic acid type, a carboxylic acid type, a nonionic type, and a cationic type. These are described in, for example, JP-A-61-243837. 0.001-2 mass% is preferable with respect to a cellulose acylate, and, as for the addition amount of a mold release agent, 0.01-1 mass% is more preferable. If the addition amount is less than 0.001% by mass, the effect of addition cannot be sufficiently exerted, and if the addition amount exceeds 2% by mass, precipitation or insoluble matter may occur.
[0072]
Nonionic surfactants include surfactants having nonionic hydrophilic groups such as polyoxyethylene, polyoxypropylene, polyoxybutylene, polyglycidyl and sorbitan, and specifically include polyoxyethylene alkyl ethers, polyoxyethylene alkyl ethers, and polyoxyethylene alkyl ethers. Oxyethylene alkyl phenyl ether, polyoxyethylene-polyoxypropylene glycol, polyhydric alcohol fatty acid partial ester, polyoxyethylene polyhydric alcohol fatty acid partial ester, polyoxyethylene fatty acid ester, polyglycerin fatty acid ester, fatty acid diethanolamide, triethanolamine Mention may be made of fatty acid partial esters.
[0073]
Examples of the anionic surfactant include carboxylate, sulfate, sulfonate, and phosphate ester salt. Representative examples include fatty acid salt, alkylbenzene sulfonate, alkyl naphthalene sulfonate, alkyl sulfonate, α-olefin sulfonate, dialkylsulfosuccinate, α-sulfonated fatty acid salt, N-methyl-N oleyl taurine, petroleum sulfonate, alkyl sulfate, sulfated oil, polyoxyethylene alkyl ether sulfate, poly Examples thereof include oxyethylene alkyl phenyl ether sulfate, polyoxyethylene styrenated phenyl ether sulfate, alkyl phosphate, polyoxyethylene alkyl ether phosphate, and naphthalene sulfonate formaldehyde condensate.
[0074]
Examples of cationic surfactants include amine salts, quaternary ammonium salts, pyridinium salts, and the like. Primary to tertiary fatty amine salts, quaternary ammonium salts (tetraalkyl ammonium salts, trialkylbenzyl ammonium salts, Alkyl pyridium salt, alkyl imidazolium salt, etc.). Examples of amphoteric surfactants include carboxybetaine and sulfobetaine, such as N-trialkyl-N-carboxymethylammonium betaine and N-trialkyl-N-sulfoalkyleneammonium betaine.
[0075]
By adding the fluorosurfactant, an antistatic effect can be exhibited. The addition amount of the fluorosurfactant is preferably 0.002 to 2% by mass and more preferably 0.01 to 0.5% by mass with respect to the cellulose acylate. If the addition amount is less than 0.002% by mass, the effect of addition cannot be sufficiently exhibited, and if the addition amount exceeds 2% by mass, precipitation or insoluble matter may occur.
[0076]
In the present invention, a retardation increasing agent (optical property adjusting agent) can be added. The optical anisotropy can be controlled by adding a retardation increasing agent. The retardation increasing agent is preferably an aromatic compound having at least two aromatic rings in order to adjust the retardation of the cellulose acylate film. An aromatic compound is used in 0.01-20 mass parts with respect to 100 mass parts of cellulose acylates. The aromatic compound is preferably used in the range of 0.05 to 15 parts by mass, and more preferably in the range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the cellulose acylate. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic hetero ring in addition to the aromatic hydrocarbon ring.
[0077]
The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring). The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring.
[0078]
In the present invention, a colorant can be added. By adding a colorant, light piping can be prevented when used for a photosensitive material support. The amount of the colorant added is preferably 10 to 1000 ppm, more preferably 50 to 500 ppm, by weight with respect to cellulose acylate.
[0079]
In addition, a heat stabilizer such as an alkaline earth metal salt such as lucium and magnesium, an antistatic agent, a flame retardant, a lubricant, an oil agent, and the like can be appropriately added to the dope in the present invention as necessary.
[0080]
It describes about the optical characteristic of the film manufactured by the solution casting method of this invention. First, the in-plane retardation (Re) of the film will be described. The measurement method uses an ellipsometer (Ellipsometer AEP-100: manufactured by Shimadzu Corporation), and the in-plane longitudinal and lateral directions at a wavelength of 632.8 nm. Is obtained by multiplying the difference in refractive index by the film thickness.
Re = (nx−ny) × d
nx: refractive index in the horizontal direction
ny: longitudinal refractive index
[0081]
The smaller the retardation (Re) is, the smaller the optical anisotropy in the in-plane direction is, and it is used in the range of 0 to 300 nm depending on the application. The retardation in the thickness direction (Rth) of the film is also important, and is obtained by multiplying the birefringence in the thickness direction at a wavelength of 632.8 nm by the film thickness, and is obtained by the following formula.
Rth = {(nx + ny) / 2−nz} × d
nx: refractive index in the horizontal direction
ny: longitudinal refractive index
nz: refractive index in the thickness direction
[0082]
A smaller refractive index in the thickness direction indicates that there is no optical anisotropy in the thickness direction, but a preferable range is determined depending on the intended use. In general, the Rth of the cellulose acylate film produced according to the present invention is 0 nm to 600 nm per 100 μm, and further used at 0 nm to 400 nm.
[0083]
Films produced by the solution casting method of the present invention can be used as optical films such as polarizing plate protective films, optical compensation sheets, AR, LR, AG film support films, and support films for photographic materials. Can be used.
[0084]
When the film produced by the solution casting method of the present invention is used as an optical compensation sheet, the film itself can be used as the optical compensation sheet. When the film itself is used as an optical compensation sheet, it is preferable to arrange the transmission axis of the polarizing plate and the slow axis of the optical compensation sheet so that they are substantially parallel or perpendicular. The arrangement of the polarizing plate and the optical compensation sheet is described in JP-A-10-48420. The liquid crystal display device comprises a liquid crystal cell having a liquid crystal supported between two electrode substrates, two polarizing plates disposed on both sides thereof, and at least one sheet between the liquid crystal cell and the polarizing plate. An optical compensation sheet is arranged.
[0085]
The liquid crystal layer of the liquid crystal cell is usually formed by sealing liquid crystal in a space formed by sandwiching a spacer between two substrates. The transparent electrode layer is formed on the substrate as a transparent film containing a conductive substance. The liquid crystal cell may further be provided with a gas barrier layer, a hard coat layer, or an undercoat layer (undercoat layer) (used for adhesion of the transparent electrode layer). These layers are usually provided on the substrate. The substrate of the liquid crystal cell generally has a thickness of 50 μm to 2 mm.
[0086]
The optical compensation sheet has birefringence and is used for the purpose of removing the color of the display screen of the liquid crystal display device or improving the viewing angle characteristics. The cellulose acylate film itself according to the present invention can be used as an optical compensation sheet. Further, the function may be imparted as an antireflection layer, an antiglare layer, a λ / 4 layer or a biaxially stretched cellulose acylate film. In addition, in order to improve the viewing angle of the liquid crystal display device, the cellulose acylate film of the present technology and a film exhibiting a birefringence opposite to that (a positive / negative relationship) may be used as an optical compensation sheet. .
[0087]
In addition, optical compensation sheets in which an optically anisotropic layer containing a liquid crystal compound (particularly a discotic liquid crystal molecule) is provided on a support have been proposed (Japanese Patent Laid-Open Nos. 3-9325 and 6-148429). 8-50206 and 9-26572). The film produced by the solution casting method of the present invention can also be used as a support for such an optical compensation sheet.
[0088]
Examples of the polarizing element of the polarizing plate include an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film. Any polarizing element is generally manufactured using a polyvinyl alcohol film. The protective film of the polarizing plate preferably has a thickness of 25 to 350 μm, and more preferably 40 to 200 μm. The liquid crystal display device may be provided with a surface treatment film. The functions of the surface treatment film include hard coat, anti-fogging treatment, anti-glare treatment and anti-reflection treatment.
[0089]
The optically anisotropic layer is preferably a layer containing negatively uniaxially tilted and aligned discotic liquid crystal molecules. The layer containing the discotic liquid crystalline molecules may be hybrid-aligned in which the angle formed by the disk surface and the support surface changes in the depth direction of the optically anisotropic layer, and the disk surface is parallel to the support surface. Homeotropic alignment, homogeneous alignment in which the disk surface is perpendicular to the support surface, or twist alignment in which the disk surface is twisted in the depth direction of the optically anisotropic layer may be employed. Moreover, the orientation in which these orientations are mixed (for example, hybrid orientation + twist orientation) may be used. Among these, the hybrid orientation is preferable. The optical axis of each discotic liquid crystalline molecule exists in the normal direction of the disk surface. However, the optical axis does not exist in the entire layer in which the discotic liquid crystalline molecules are hybrid-aligned.
[0090]
The film produced by the solution casting method of the present invention can be used for liquid crystal cells in various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroelectric Liquid Nyst) Various display modes such as HAN (Hybrid Aligned Nematic) have been proposed. In addition, a display mode in which the above display mode is oriented and divided has been proposed. The cellulose acylate film is effective in any display mode liquid crystal display device. Further, it is effective in any of a transmissive, reflective, and transflective liquid crystal display device.
[0091]
The film produced by the solution casting method of the present invention may be used as a support for an optical compensation sheet of a TN type liquid crystal display device having a TN mode liquid crystal cell. TN mode liquid crystal cells and TN type liquid crystal display devices have been well known for a long time. The optical compensation sheet used for the TN liquid crystal display device is described in JP-A-3-9325, JP-A-6-148429, JP-A-8-50206, and JP-A-9-26572. Moreover, it is described in Mori et al. (Jpn. J. Appl. Phys. Vol. 36 (1997) p. 143 and Jpn. J. Appl. Phys. Vol. 36 (1997) p. 1068). is there. The TN liquid crystal display device is described in JP-A-10-123478, WO98848320, and Japanese Patent No. 3022477.
[0092]
You may use the film manufactured by the solution casting method of this invention as a support body of the optical compensation sheet | seat of the STN type liquid crystal display device which has a liquid crystal cell of STN mode. In general, in a STN type liquid crystal display device, rod-like liquid crystalline molecules in a liquid crystal cell are twisted in the range of 90 to 360 degrees, and the refractive index anisotropy (Δn) and cell gap (d) of the rod-like liquid crystalline molecules. Product (Δnd) is in the range of 300 to 1500 nm. The optical compensation sheet used in the STN type liquid crystal display device is described in JP-A-2000-105316.
[0093]
The film produced by the solution casting method of the present invention may be used as a support for an optical compensation sheet of a VA liquid crystal display device having a VA mode liquid crystal cell. In the optical compensation sheet used for the VA liquid crystal display device, it is preferable that the direction in which the absolute value of retardation is minimum does not exist in the plane of the optical compensation sheet or in the normal direction. The optical properties of the optical compensation sheet used in the VA liquid crystal display device are determined by the optical properties of the optically anisotropic layer, the optical properties of the support, and the arrangement of the optically anisotropic layer and the support. . When two optical compensation sheets are used in the VA liquid crystal display device, the in-plane retardation of the optical compensation sheet is preferably in the range of −5 nm to 5 nm. Therefore, the absolute value of the in-plane retardation of each of the two optical compensation sheets is preferably 0 to 5. When one optical compensation sheet is used in the VA liquid crystal display device, it is preferable that the in-plane retardation of the optical compensation sheet be in the range of −10 nm to 10 nm.
[0094]
The film produced by the solution casting method of the present invention may be used as a support for an optical compensation sheet of an OCB type liquid crystal display device having an OCB mode liquid crystal cell or a HAN type liquid crystal display device having a HAN mode liquid crystal cell. Good. In the optical compensation sheet used for the OCB type liquid crystal display device or the HAN type liquid crystal display device, it is preferable that the direction in which the absolute value of retardation is minimum does not exist in the plane of the optical compensation sheet or in the normal direction. The optical properties of the optical compensation sheet used in the OCB type liquid crystal display device or the HAN type liquid crystal display device are also the optical properties of the optically anisotropic layer, the optical properties of the support, and the optically anisotropic layer and the support. Is determined by the arrangement of An optical compensation sheet used for an OCB type liquid crystal display device or a HAN type liquid crystal display device is described in JP-A-9-197397. Moreover, it is described in Mori et al. (Jpn. J. Appl. Phys. Vol. 38 (1999) p. 2837).
[0095]
The film produced by the solution casting method of the present invention may be used as a support for an optical compensation sheet of an ASM type liquid crystal display device having a liquid crystal cell of ASM (Axial Symmetrical Microcell) mode. The ASM mode liquid crystal cell is characterized in that the thickness of the cell is maintained by a resin spacer whose position can be adjusted. Other properties are the same as those of the TN mode liquid crystal cell. The ASM mode liquid crystal cell and the ASM type liquid crystal display device are described in a paper (Kume et al., SID 98 Digest 1089 (1998)) outside Kume.
[0096]
An embodiment of a solution casting apparatus for carrying out the solution casting method of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of a solution casting apparatus, and FIG. 2 is an enlarged view of a stripped portion of the solution casting apparatus.
[0097]
In FIG. 1, reference numeral 1 denotes a mixing tank, which is prepared by adding cellulose triacetate, an additive and a solvent. The mixing tank 1 is connected to a casting die 4 via a liquid feed pump 2 and a filter 3. The dope liquid feeding step including the mixing tank 1, the liquid feed pump 2, and the filter 3 is provided in three sets so that a film having a three-layer structure can be manufactured. Below the casting die 4, a casting band 5 made of stainless steel as a casting support is disposed. The casting band 5 is wound around the rotating drums 6 and 7 and is rotated. A plurality of guide rolls 8 are provided between the drum 6 and the rotating drum 7. Further, above and below the casting band 5, drying air blowing means (not shown) is provided for blowing hot air on the dope cast on the casting band 5 to dry the dope. A stripping roll 9 is provided adjacent to the rotary drum 6 on the casting die 4 side, a number of guide rolls 10 and a winding roll 11 are further provided, and a drying unit is provided between the stripping roll 9 and the winding roll 11. 12
[0098]
In order to form a film with the solution casting apparatus as described above, the dope is discharged from the casting die 4, cast into the casting band 5, and conveyed while being dried on the casting band 5. The film dried to some extent on the casting band 5 is peeled off from the casting band 5 by a peeling roll 9. At this time, the film peeling angle is adjusted to a predetermined range. The peeling angle will be described with reference to FIG.
[0099]
In FIG. 2, the film 14 indicated by the solid line is peeled off from the casting band 5 at the peeling point a. At this time, when the tangential direction h at the peeling point a is 0 degree and the normal direction v is 90 degrees. The film 14 peeling angle (angle formed between the tangential direction h and the film) θ is set in the range of 30 to 80 degrees, specifically about 75 degrees. Similarly, in the case of the film 14 indicated by a two-dot chain line, the peeling angle θ ′ at the peeling point a ′ is set in the range of 30 to 80 degrees in the tangential direction h ′ and the normal direction v ′. Specifically, it is about 31 degrees. Further, assuming that the peripheral speed V1 of the casting band 5 and the peripheral speed V2 of the peeling roll 9 are set to be in a range of (V2−V1) /V1=0.005 to 1.0.
[0100]
Furthermore, if the distance between the peeling point a of the casting band 5 and the contact point b of the peeling roll 9 is L, L / (V1 + V2) /2=0.03 to 0.3 seconds is set. Yes.
[0101]
A film that can be produced by the solution casting method of the present invention will be described with reference to FIGS. 3 and 4 are cross-sectional views schematically showing the film.
[0102]
The film 21A shown in FIG. 3 is formed so that the elastic modulus of the outer surface 21a on one side is lower than the elastic modulus of the inner 21b. The film 21B is formed such that the elastic modulus of the outer surfaces 21a and 21c on both sides is lower than the elastic modulus of the inner 21b.
[0103]
The film 22A shown in FIG. 4 has a two-layer structure, and is formed such that the elastic modulus of the surface layer 22a on one side is lower than the elastic modulus of the inside 22b. The film 22B has a three-layer structure, and is formed such that the elastic modulus of the surface layers 22a and 22c on both sides is lower than the elastic modulus of the inner part 22b.
[0104]
In addition, this invention is not limited to these layer structures, For example, the multilayered structure of four or more layers may be sufficient.
[0105]
An example of a co-casting method that can be used in the solution casting method of the present invention will be described with reference to FIGS.
[0106]
FIG. 5 is a schematic sectional view of the die, and FIG. 6 is a schematic sectional view of the feed block. The co-casting method shown in FIG. 5 uses a co-casting die 30 provided with a feed block 31 as shown in FIG. 6, and the dopes 32 are joined by the feed block 31 before the co-casting die 30. Then, the dope 32 is discharged from the co-casting die 30 onto the support 33 moving at a constant speed in the direction of the arrow and simultaneously cast.
[0107]
FIG. 7 is a schematic sectional view of a die showing an example of another co-casting method. The co-casting method shown in FIG. 7 is a multi-manifold die in which the co-casting die 40 has three manifolds 41, 42, and 43. After the dope 44 is joined inside the co-casting die 40, In this method, the dope 44 is discharged from the rolling die 40 onto the support 45 and simultaneously cast.
[0108]
Next, a sequential casting method that can be used in the solution casting method of the present invention will be described with reference to FIG.
[0109]
FIG. 8 is a schematic sectional view of the die. In the sequential casting method shown in FIG. 8, three dies 50, 60, 70 are arranged on the support 80, and the dopes 51, 61, 71 are flowed from the dies 50, 60, 70 onto the support 80, respectively. At this time, the die 60 on the downstream side casts the dope 61 on the upper surface of the dope 51 cast by the die 50 on the upstream side, and the die 70 on the downstream side is on the upstream side. The dope 71 is cast on the upper surface of the dope 61 cast by the die 60 on the side, and a film having a three-layer structure can be formed.
[0110]
Moreover, the example of the solution casting apparatus which can be utilized for the solution casting method of this invention is shown to FIGS.
[0111]
The solution casting apparatus shown in FIG. 9 uses a casting band as a casting support. The solution casting apparatus shown in FIG. 10 uses a casting band as a casting support and also uses a tenter. The solution casting apparatus shown in FIG. 11 also uses a casting band as a casting support and also uses a tenter. The solution casting apparatus shown in FIG. 12 also uses a casting band as a casting support and also uses a tenter. The solution casting apparatus shown in FIG. 13 also uses a casting band as a casting support, and also uses a tenter and heat transfer means. The solution casting apparatus shown in FIG. 14 also uses a casting band as a casting support, and also uses a tenter and heat transfer means. The solution casting apparatus shown in FIG. 15 also uses a casting band as a casting support, and also uses a tenter and heat transfer means. The solution casting apparatus shown in FIG. 16 uses a cooling drum as a casting support and also uses a tenter. The solution casting apparatus shown in FIG. 17 also uses a cooling drum as a casting support, and also uses a tenter. The solution casting apparatus shown in FIG. 18 uses a drying drum as a casting support and also uses a tenter.
[0112]
In the above solution casting apparatus, 81 is a die, 82 is a casting support, 83 is a drying apparatus, and 84 is a tenter.
[0113]
【Example】
[Examples 1 to 12, 14 and Comparative Examples 1 to 3]
Single-layer film formation was performed using the solution film-forming apparatus shown in FIG.
[0114]
The composition of the dope used is as follows.
Cellulose triacetate (acetylation degree 60.9%) 20.4 parts by mass
Triphenyl phosphate 3.1 parts by mass
Dichloromethane 65.0 parts by mass
5.4 parts by mass of n-butanol
9.1 parts by mass of methanol
[0115]
Using the above dope, the peeling angle, the circumferential speed V1 of the casting support, the circumferential speed V2 of the peeling rope, the distance L from the peeling point from the casting support and the contact point in contact with the peeling roll, A cellulose triacetate film was produced by changing the residual solvent amount, the longitudinal elastic modulus, the thickness, the ear edge maximum thickness, and the surface layer thickness (in the case of a two-layer structure).
[0116]
[Implementation 13]
Using the solution casting apparatus shown in FIG. 1, two layers were formed.
[0117]
The composition of the dope used is as follows.
<Surface layer (support side)>
Cellulose triacetate (acetylation degree 60.9%) 20.4 parts by mass
Triphenyl phosphate 3.1 parts by mass
Dichloromethane 65.0 parts by mass
5.4 parts by mass of n-butanol
9.1 parts by mass of methanol
Citric acid 0.03 parts by mass
[0118]
<Core layer>
Cellulose triacetate (acetylation degree 60.9%) 20.4 parts by mass
Triphenyl phosphate 3.1 parts by mass
Dichloromethane 65.0 parts by mass
5.4 parts by mass of n-butanol
9.1 parts by mass of methanol
[0119]
Using the above dope, a cellulose triacetate film consisting of two layers was produced by co-casting.
[0120]
The unevenness and haze of Examples 1 to 14 and Comparative Examples 1 to 3 were evaluated. The evaluation results are shown in Table 1.
[0121]
[Table 1]

[0122]
[Evaluation of unevenness]
The film was visually observed and evaluated. The contents of evaluation are as follows.
A: Level at which unevenness cannot be seen
○: Unevenness is visible, but at a level better than the unevenness limit
Δ: Same level as unevenness limit
X: Level worse than unevenness limit
[0123]
[Transparency]
The transmittance of visible light 615 nm was measured.
[0124]
【The invention's effect】
By configuring the present invention as described above, it is possible to produce a film with good flatness without causing unevenness in steps and unevenness when peeling the film from the casting support.
[Brief description of the drawings]
FIG. 1 is a schematic view of an embodiment of a solution casting apparatus for performing a solution casting method according to the present invention.
FIG. 2 is an enlarged view of a stripped portion of an embodiment of a solution casting apparatus for performing a solution casting method according to the present invention.
FIG. 3 is a cross-sectional view schematically showing a film that can be produced by the solution casting method of the present invention.
FIG. 4 is a cross-sectional view schematically showing a film that can be produced by the solution casting method of the present invention.
FIG. 5 is a schematic cross-sectional view of a die that can be used in the solution casting method of the present invention.
FIG. 6 is a schematic cross-sectional view of a feed block that can be used in the solution casting method of the present invention.
FIG. 7 is a schematic cross-sectional view of a die that can be used in the solution casting method of the present invention.
FIG. 8 is a schematic cross-sectional view of a die that can be used in the solution casting method of the present invention.
FIG. 9 is a schematic view of a solution casting apparatus that can be used in the solution casting method of the present invention.
FIG. 10 is a schematic view of a solution casting apparatus that can be used in the solution casting method of the present invention.
FIG. 11 is a schematic view of a solution casting apparatus that can be used in the solution casting method of the present invention.
FIG. 12 is a schematic view of a solution casting apparatus that can be used in the solution casting method of the present invention.
FIG. 13 is a schematic view of a solution casting apparatus that can be used in the solution casting method of the present invention.
FIG. 14 is a schematic view of a solution casting apparatus that can be used in the solution casting method of the present invention.
FIG. 15 is a schematic view of a solution casting apparatus that can be used in the solution casting method of the present invention.
FIG. 16 is a schematic view of a solution casting apparatus that can be used in the solution casting method of the present invention.
FIG. 17 is a schematic view of a solution casting apparatus that can be used in the solution casting method of the present invention.
FIG. 18 is a schematic view of a solution casting apparatus that can be used in the solution casting method of the present invention.
[Explanation of symbols]
1 ... Mixing tank
2 ... Liquid pump
3 ... Filter
4 ... Casting die
5 ... Casting band
6, 7 ... Rotating drum
8 ... Guide roll
9 ... Stripping roll
10 ... Guide roll
11 ... take-up roll
12 ... Drying section
14 ... Film
a ... Peeling point
b ... Contact point
h ... tangential direction
v ... Normal direction
θ ... Stripping angle

Claims (20)

  A dope composed of a polymer, a solvent and an additive is cast from a casting die to a casting support, the cast dope is dried to some extent to form a film, and the film is peeled off from the casting support with a roll. In the solution casting method in which the film is further dried and then dried to produce a film, the tangential direction on the film traveling direction side at the peeling point of the casting support of the film peeled off from the casting support is 0 degree, normal When the direction is 90 degrees, the film peeling angle is in the range of 30 to 80 degrees, the circumferential speed of the casting support is V1, and the circumferential speed of the peeling roll is V2. ) / V1 in the range of 0.005 to 1.0.   Two or more layers are formed, an additive for reducing the peeling resistance from the casting support is added to the layer in contact with the casting support, and the stripping angle is adjusted by adjusting the addition amount. The solution film-forming method according to claim 1. When (V2-V1) / V1 is 0.001, the film tension immediately after peeling is F (kg), the average film width between the peeling rolls from the peeling point is W (mm), and the average film thickness is S ( mm), and E = F / (S × W × 0.001), E is 0.01 to 7 (kgf / mm ² ), The solution casting according to claim 1 or 2 Method.   The solution casting method according to claim 3, wherein the E is controlled by adjusting a casting support temperature at a peeling point in a range of -30 to 60 ° C.   At the peeling point where the film is peeled off from the casting support, the weight of the solid content of the film is P, the weight of the solvent amount is Q, and the residual solvent amount of the film is R = Q / P × 100 (wt%). The solution casting method according to claim 1 or 3, wherein the residual solvent amount R is 120 wt% or more.   At the peeling point where the film is peeled off from the casting support, when the force in the normal direction of the casting support surface necessary for peeling is defined as the peeling resistance, the peeling resistance is less than 100 gf per 1 cm of the film. The solution casting method according to claim 1, 2 or 3.   At the peeling point where the film is peeled off from the casting support, when the maximum thickness in the film width direction end portion is X and the average film thickness in the product range is Y in terms of thickness after drying, Y is in the range of 20 to 300 μm. The solution casting method according to claim 1, wherein the accuracy is within ± 3%, and the thickness ratio Z = X / Y is 0.5 <Z <2.0.   The solution casting method according to claim 1 or 3, wherein a clearance CL between the casting support and the peeling roll is in a range of 1 to 30 mm.   The solution casting method according to claim 1 or 3, wherein the peeling roll radius R is 30 mm or more, and the roll surface temperature is set to -20 to 80 ° C.   2. A feed block system in which a confluence is provided at the entrance of a single-layer die or a multi-manifold system having two or more systems in a die is used for casting two or more layers simultaneously. Or the solution casting method of 3.   The solution casting method according to claim 1 or 3, wherein a stainless steel band having a mirror surface having no pinhole having a maximum outer diameter of 30 µm or more is used for the casting support.   As the casting support, a drum having a diameter of 1.5 to 5.0 m having a mirror surface of nickel chrome plating with no pinhole having a maximum outer diameter of 30 μm or more is used, and a jacket provided on the drum has a temperature of −40 to 70 ° C. 4. The solution casting method according to claim 1, wherein the drum surface temperature is controlled by continuously passing the heating medium. Infrared rays are transmitted through the film immediately after being peeled off from the casting support, and the residual solvent amount of the film is measured in a non-contact manner from the change in the spectral absorption distribution so that the target residual solvent amount is obtained. 6. The solution casting method according to claim 5 , wherein the drying conditions in the upstream process are adjusted. The solution casting method according to claim 1, 2, 3, 4, 5, or 6 , wherein the dope contains 10% by mass or more of cellulose triacetate. In the solution casting method, the solvent of the cellulose acylate solution is composed of methyl acetate, a ketone solvent and an alcohol, and the solvent ratio is 20 to 90% by mass of methyl acetate, 5 to 60% by mass of the ketone solvent, and 5% of alcohol. The solution casting method according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 or 14 , which is -30% by mass. The said dope is a cellulose acylate solution, and contains 0.1-20 mass% of at least 1 or more types of plasticizer with respect to a cellulose acylate, 1, 2, 3, 4, 5, 6, The solution casting method according to 7, 8, 9, 10, 11, 12 , 13 , 14 or 15 . The said dope is a cellulose acylate solution, and contains 0.001-5 mass% of at least 1 or more types of ultraviolet absorber with respect to a cellulose acylate, Claim 1, 2, 3, 4, 5, 6 , 7, 8, 9, 10, 11, 12, 13 , 15, or 16 . The said dope is a cellulose acylate solution, and contains 0.001-5 mass% of at least 1 or more types of fine particle powder with respect to a cellulose acylate, 1, 2, 3, 4, 5, 6 , 7, 8, 9, 10, 11, 12, 13 , 15 , 16 or 17 . The dope is a cellulose acylate solution and contains at least one or more release agents in an amount of 0.001 to 2 mass% with respect to the cellulose acylate. , 7, 8, 9, 10, 11, 12, 13, 15 , 17, or 18 . The dope is a cellulose acylate solution and contains at least one or more fluorine-based surfactants in an amount of 0.002 to 2 mass% with respect to the cellulose acylate. The solution casting method according to 3, 4, 5, 6, 7 , 8, 9, 10, 11 , 12, 13 , 15 , 16, 17 , or 18 .

Images