JP2004029199A - Method for manufacturing cellulose acylate film, cellulose acylate film obtained by the method and polarizing plate using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a cellulose acylate film having excellent strippability of a dope film, free of film breakage in web handling and free of leaching of an additive and to provide a cellulose acylate film and a polarizing plate having excellent optical properties such as planeness and transparency. <P>SOLUTION: There is described a method for manufacturing a cellulose acylate film by casting a cellulose acylate dope solution containing an ethylenically unsaturated monomer and/or an ethylenically unsaturated monomer having a functional group and a photopolymerization initiator from a casting die on a casting support. When the dope solution on the casting support is irradiated with UV, the concentration of oxygen in an UV irradiation booth is regulated to ≤10%. A cellulose acylate film obtained by the method and a polarizing plate using the film are also provided. <P>COPYRIGHT: (C)2004,JPO

Description

【００８３】
【化２】

【００８４】
【化３】

【００８５】
【化４】

【００８６】
【化５】

【００８７】
【化６】

【００８８】
【化７】

【００８９】
（光ラジカル重合開始剤）
本発明に有用な光重合開始剤としては、エチレン性不飽和モノマーがウェブ中で光重合し得る開始剤であれば制限なく使用できるが、これらの光重合開始剤は公知のものを使用し得る。また光増感剤も使用出来る。具体的には、ベンゾインメチルエーテル、ベンゾイン−ｎ−プロピルエーテル、ベンゾイン−ｎ−ブチルエーテル、ベンゾインシリルエーテル、メチルベンゾインホルメート、ベンジル、ベンゾフェノン、ヒドロキシベンゾフェノン、ｐ−メチルベンゾフェノン、α−ヒドロキシイソブチルフェノン、ｐ−イソプロピル−α−ヒドロキシイソブチルフェノン、アセトフェノン、ミヒラーズケトン、α，α′−ジクロロ−４−フェノキシアセトフェノン、１−ヒドロキシ−１−シクロヘキシルアセトフェノン、２，２−ジメトキシ−２−フェニルアセトフェノン、ジアセチル、エオシン、チオニン、２−メチル−１−〔４−（メチルチオ）フェニル〕−２−モルホリノプロペン、ジクロロチオキサントン、ジイソプロピルチオキサントン、フェニルジスルフィド−２−ニトロソフルオレン、ブチロイン、アニソインエチルエーテル、ジ−ｔ−ブチルパーオキシド、ベンゾイルチアゾリルスルフィド、α−アミロキシムエステル、アゾビスイソブチロニトリル、テトラメチルチウラムジスルフィド等を挙げることができる。本発明において、セルロースアシレートドープ組成物中にエチレン性不飽和モノマーと共に光重合開始剤を混合する場合、セルロースアシレートに対してエチレン性不飽和モノマーを５〜３０質量％、また光重合開始剤をエチレン性不飽和モノマーに対して１〜３０質量％程度加えるのがよい。本発明においては、光重合性のエチレン性不飽和モノマーをセルロースアシレートドープ組成物流延後、有機溶媒を多く含むウェブにおいても、またかなり乾燥が進んでいてもウェブ内で光重合を起こさせることができるが、金属支持体上で、紫外線を照射して重合させるのが好ましい。
【００９０】
本発明のエチレン性不飽和モノマーと光重合開始剤を含有するセルロースアシレートドープ組成物に二つのエチレン性不飽和基を有する架橋性モノマーを含有させることにより、光重合後、しなやかさと強靱性を兼ね備えたセルロースアシレートフィルムを得ることが出来る。この二つのエチレン性不飽和基を有する架橋性モノマーとしては、ポリエステルジ（メタ）アクリレート、ポリウレタンジ（メタ）アクリレート等を挙げることができる。市販品として、東亜合成社製のウレタンアクリレート（商品名、Ｍ−１３１０）があり、好ましく用いることができる。
【００９１】
これらのポリエステルまたはポリウレタンのジ（メタ）アクリレートは、数平均分子量として、６，０００〜１００，０００、好ましくは１０，０００〜８０，０００のものである。
【００９２】
（３員又は４員環状エーテル類）
本発明のセルロースアシレート溶液に添加される重合性モノマー又は重合性化合物の別の一例はエポキシ基を有する化合物である。ここで、３員環の環状エーテル基を有する化合物としては３員又は４員環の環状エーテル基を有する化合物が挙げられ、又、４員環の環状エーテル基を有する化合物としては、オキセタニル基を有する化合物が挙げられる。前記の環状エーテル基を有する化合物としては、エポキシ基を有する化合物、特に脂環式エポキシ基を有する化合物が反応性が高い点で好ましい。
以下の説明において、３員又は４員環の環状エーテル基を有する化合物の説明において、エポキシ基を有する化合物を例に挙げて説明するが、本発明はオキセタニル基を有する化合物にも容易に拡張できるものである。
これらのエポキシ基を有する化合物もウェブ内で光重合させることができ、でき上がったフィルムに可塑性を付与することができる。エポキシ基を有する化合物としては、通常接着剤等に使用し得るものを使用することができる。
【００９３】
本発明に有用なエポキシ基を有する化合物を例示すると、芳香族エポキシ化合物（多価フェノールのポリグリシジルエーテル）としては、水素添加ビスフェノールＡまたはビスフェノールＡとエピクロルヒドリンとの反応物のグリシジルエーテル、エポキシノボラック樹脂（例えば、クレゾールノボラックポリグリシジルエーテル、フェノールノボラックポリグリシジルエーテル）、レゾールエポキシ樹脂、レゾルシノールジグリシジルエーテル等が挙げられ、又、脂肪族エポキシ樹脂としては、脂肪族多価アルコールまたはそのアルキレンオキサイド付加物のポリグリシジルエーテル、脂肪族長鎖多塩基酸のポリグリシジルエステル、グリシジルアクリレートやグリシジルメタクリレートのホモポリマー、コポリマーなどがあり、その代表例としては、エチレングリコールジグリシジルエーテル、プロピレングリコールジグリシジルエーテル、ジエチレングリコールジグリシジルエーテル、ジプロピレングリコールジグリシジルエーテル、トリプロピレングリコールグリシジルエーテル、１，４−ブタンジオールジグリシジルエーテル、１，６−ヘキサンジオールジグリシジルエーテル、ノナプロピレングリコールジグリシジルエーテル、ネオペンチルグリコールジグリシジルエーテル、グリセリントリグリシジルエーテル、ジグリセロールトリグリシジルエーテル、ジグリセロールテトラグリシジルエーテル、トリメチロールプロパントリグリシジルエーテル、ペンタエリスリトールトリグリシジルエーテル、ペンタエリスリトールテトラグリシジルエーテル、ソルビトールのポリグリシジルエーテル、脂環式エポキシ化合物、例えば、３，４−エポキシシクロヘキシルメチル−３′，４′−エポキシシクロヘキサンカルボキシレート、２−（３，４−エポキシシクロヘキシル−５，５−スピロ−３′，４′−エポキシ）シクロヘキサン−メタ−ジオキサン、ビス（３，４−エポキシシクロヘキシルメチル）アジペート、ビニルシクロヘキセンジオキサイド、ビス（３，４−エポキシ−６−メチルシクロヘキシルメチル）アジペート、３，４−エポキシ−６−メチルシクロヘキシル−３′，４′−エポキシ−６−メチルシクロヘキサンカルボキシレート、メチレンビス（３，４−エポキシシクロヘキサン）ジシクロペンタジエンジエポキサイド、エチレングリコールのジ（３，４−エポキシシクロヘキシルメチル）エーテル、エチレンビス（３，４−エポキシシクロヘキサンカルボキシレート）、ジシクロペンタジエンジエポキサイド、トリス（２−ヒドロキシエチル）イソシアヌレートのジグリシジルエーテル、トリス（２−ヒドロキシエチル）イソシアヌレートのトリグリシジルエーテル、ポリグリシジルアクリレート、ポリグリシジルメタクリレート、グリシジルアクリレートまたはグリシジルメタクリレートと他のモノマーとの共重合物、ポリ−２−グリシジルオキシエチルアクリレート、ポリ−２−グリシジルオキシエチルメタクリレート、２−グリシジルオキシエチルアクリレート、２−グリシジルオキシエチルアクリレートまたは２−グリシジルオキシエチルメタクリレートと他のモノマーとの共重合物、ビス−２，２−ヒドロキシシクロヘキシルプロパンジグリシジルエーテル等を挙げることができ、２種以上組み合わせて使用することができる。本発明においては、上記の例示化合物に限定されず、これらから類推される化合物も含むものである。
【００９４】
また、本発明において、３員又は４員環の環状エーテル基を分子内に２つ以上有する化合物以外に、３員又は４員環の環状エーテル基を分子内に１つのみ有する化合物も所望の性能に応じて配合して使用することができる。
【００９５】
本発明における紫外線重合性の３員又は４員環の環状エーテル基を有する化合物は、ラジカル重合反応によるのではなく、カチオン重合反応により重合物、架橋構造物または網目構造物を形成する。ラジカル重合と異なり反応系中の酸素に影響を受けないため誘導期間がなく重合を速く行うことができる。
【００９６】
以下に本発明において使用できる３員又は４員環の環状エーテル基を有する化合物の代表例を例示するが、これらに限定されるものではない。
【００９７】
【化８】

【００９８】
【化９】

【００９９】
（光カチオン重合開始剤）
本発明に有用な３員又は４員環の環状エーテル基を有する化合物は、紫外線照射によりカチオン重合を開始する物質を生成する化合物が触媒になってカチオン重合反応が進行する。紫外線照射によりカチオン重合を開始するものとしてはルイス酸を放出するオニウム塩の複塩の一群が特に好ましい。
【０１００】
かかる代表的なものは下記一般式（Ｉ）で表される化合物である。
一般式（Ｉ）
〔（Ｒ^１）_ａ（Ｒ^２）_ｂ（Ｒ^３）_ｃ（Ｒ^４）_ｄＺ〕^＋ｗ〔ＭｅＸｖ＋ｗ〕^−ｗ
ここで、式中、カチオンはオニウムであり、ＺはＳ、Ｓｅ、Ｔｅ、Ｐ、Ａｓ、Ｓｂ、Ｂｉ、Ｏ、ハロゲン（例えばＩ、Ｂｒ、Ｃｌ）、またはＮ＝Ｎ（ジアゾ）であり、Ｒ^１ _ａ、Ｒ^２ _ｂ、Ｒ^３ _ｃ、Ｒ^４ _ｄは同一であっても異なっていてもよい有機の基である。ａ、ｂ、ｃ、ｄはそれぞれ０〜３の整数であって、ａ＋ｂ＋ｃ＋ｄはＺの価数に等しい。Ｍｅはハロゲン化物錯体の中心原子である金属または半金属（ｍｅｔａｌｌｏｉｄ）であり、Ｂ、Ｐ、Ａｓ、Ｓｂ、Ｆｅ、Ｓｎ、Ｂｉ、Ａｌ、Ｃａ、Ｉｎ、Ｔｉ、Ｚｎ、Ｓｃ、Ｖ、Ｃｒ、Ｍｎ、Ｃｏ等である。Ｘはハロゲンであり、ｗはハロゲン化錯体イオンの正味の電荷であり、ｖはハロゲン化錯体イオン中のハロゲン原子の数である。
【０１０１】
上記一般式（Ｉ）の陰イオン〔ＭｅＸｖ＋ｗ〕^−ｗの具体例としては、テトラフルオロボレート（ＢＦ_４ ⁻）、ヘキサフルオロホスフェート（ＰＦ_６ ⁻）、ヘキサフルオロアンチモネート（ＳｂＦ_６ ⁻）、ヘキサフルオロアルセネート（ＡｓＦ_６ ⁻）、ヘキサクロロアンチモネート（ＳｂＣｌ_６ ⁻）等を挙げることができる。
【０１０２】
更に一般式ＭＸｎ（ＯＨ）−の陰イオンも用いることができる。また、その他の陰イオンとしては過塩素酸イオン（ＣｌＯ_４ ⁻）、トリフルオロメチル亜硫酸イオン（ＣＦ_３ＳＯ_３ ⁻）、フルオロスルホン酸イオン（ＦＳＯ_３ ⁻）、トルエンスルホン酸イオン、トリニトロベンゼン酸陰イオン等を挙げることができる。
【０１０３】
このようなオニウム塩の中でも特に芳香族オニウム塩をカチオン重合開始剤として使用するのが、特に有効であり、中でも特開昭５０−１５１９９６号、同５０−１５８６８０号公報等に記載の芳香族ハロニウム塩、特開昭５０−１５１９９７号、同５２−３０８９９号、同５９−５５４２０号、同５５−１２５１０５号公報等に記載のＶＩＡ族芳香族オニウム塩、特開昭５６−８４２８号、同５６−１４９４０２号、同５７−１９２４２９号公報等に記載のオキソスルホキソニウム塩、特公昭４９−１７０４０号公報等に記載の芳香族ジアゾニウム塩、米国特許第４，１３９，６５５号明細書等に記載のチオピリリウム塩等が好ましい。また、アルミニウム錯体や光分解性ケイ素化合物系重合開始剤等を挙げることが出来る。上記カチオン重合開始剤と、前記ベンゾフェノン及びその誘導体、前記ベンゾイン及びその誘導体、前記チオキサントン及びその誘導体等の光増感剤を併用することができる。この増感剤は近紫外線領域から可視光線領域に吸収極大のあるものが好ましい。
【０１０４】
本発明において、セルロースアシレートドープ中に３員又は４員環の環状エーテル基を有する化合物と共に光重合開始剤及び／または光増感剤を混合する場合、セルロースアシレートに対して３員又は４員環の環状エーテル基を有する化合物が５〜３０質量％、また光重合開始剤が３員又は４員環の環状エーテル基を有する化合物に対して１〜３０質量％、好ましくは１〜１０質量％である。
【０１０５】
本発明に有用な３員又は４員環の環状エーテル基と紫外線吸収剤を有する化合物を光重合開始剤と混合してドープとしてもよいし、３員又は４員環の環状エーテル基を有する化合物と共に混合してドープとしてもよい。
【０１０６】
本発明に有用な３員又は４員環の環状エーテル基と紫外線吸収性基を有する化合物の紫外線吸収性基としては、ベンゾトリアゾール基、サリチル酸エステル基、ベンゾフェノン基、オキシベンゾフェノン基、シアノアクリレート基等を挙げることができ、本発明においては何れも好ましく用いることができる。特に光反応性が少なく、且つ殆ど着色のないベンゾトリアゾール基が好ましい。
【０１０７】
本発明に係る３員又は４員環の環状エーテル基と紫外線吸収性基を有する化合物を含有するセルロースアシレートドープを溶液流延製膜過程において製膜し、紫外線照射したウェブからは、紫外線吸収剤が析出あるいは揮発することがないため生産性よく、品質に優れた液晶画像表示装置用の偏光板用保護フィルムを得ることができる。また、この３員又は４員環の環状エーテル基と紫外線吸収性基を有する化合物のポリマーが前記の如くセルロースアシレートに対して耐水性を合わせ持つことがより好ましく、ポリマーのＴｇを５０℃以下とすることが好ましい。
【０１０８】
本発明における光重合したポリマーを構成する紫外線吸収性基を有する化合物単位の割合は、ポリマーのセルロースアシレートとの相溶性、セルロースアシレートフィルムの機械的性質または物理的性質が同等またはそれ以上の性質、あるいは十分な紫外線吸収性能を有するのであれば、如何なるものであってもよい（１〜１００質量％の範囲でよい）。
【０１０９】
本発明において、セルロースアシレートドープ中に３員又は４員環の環状エーテル基を有する化合物と共に光重合開始剤（場合によっては光増感剤も）を混合するが、セルロースアシレートに対して３員又は４員環の環状エーテル基を有する化合物が５〜３０質量％、また光重合開始剤が３員又は４員環の環状エーテル基を有する化合物に対して１〜３０質量％、好ましくは１〜１０質量％である。
【０１１０】
本発明のセルロースアシレート溶液に、エチレン性不飽和化合物、光ラジカル重合開始剤、３員又は４員環の環状エーテル基を有する化合物及び光カチオン重合開始剤を添加することもできる。
【０１１１】
本発明のセルロースアシレート溶液に使用されるその他の添加剤としては、セルロースアシレート塗布液に溶解・分散するものであれば良く、紫外線吸収能、帯電防止能、劣化防止能、剥離促進能、レターデーション調整能や可塑性、滑り性などを発現するものを泣き出し等の問題が生じない範囲で添加することができる。従来使用されていた可塑剤や紫外線吸収剤なども添加できる。
【０１１２】
（可塑剤）
本発明で用いることのできる添加剤としては特に限定はない。本発明で用いることのできる可塑剤としては特に限定はないが、リン酸エステル系では、トリフェニルホスフェート、トリクレジルホスフェート、クレジルジフェニルホスフェート、オクチルジフェニルホスフェート、ジフェニルビフェニルホスフェート、トリオクチルホスフェート、トリブチルホスフェート等、フタル酸エステル系では、ジエチルフタレート、ジメトキシエチルフタレート、ジメチルフタレート、ジオクチルフタレート等、グリコール酸エステル系では、トリアセチン、トリブチリン、ブチルフタリルブチルグリコレート、エチルフタリルエチルグリコレート、メチルフタリルエチルグリコレート、ブチルフタリルブチルグリコレート等を単独あるいは併用するのが好ましい。さらに、特開平１１−８０３８１号公報、同１１−１２４４４５号公報、同１１−２４８９４０号公報に記載されている可塑剤も添加することができる。これら可塑剤は、セルロースアシレートに対して０．１〜２０重量％を含むようにドープ中に混合することが望ましい。
【０１１３】
（紫外線吸収剤）
また、ドープには、紫外線吸収剤を添加することもできる。特に、好ましくは一種または二種以上の紫外線吸収剤を含有することである。液晶用紫外線吸収剤は、液晶の劣化防止の観点から、波長３７０ｎｍ以下の紫外線の吸収能に優れ、かつ、液晶表示性の観点から、波長４００ｎｍ以上の可視光の吸収が少ないものが好ましい。例えば、オキシベンゾフェノン系化合物，ベンゾトリアゾール系化合物，サリチル酸エステル系化合物，ベンゾフェノン系化合物，シアノアクリレート系化合物，ニッケル錯塩系化合物などが挙げられる。特に好ましい紫外線吸収剤は、ベンゾトリアゾール系化合物やベンゾフェノン系化合物である。中でも、ベンゾトリアゾール系化合物は、セルロースエステルに対する不要な着色が少ないことから、好ましい。さらには、特開平８−２９６１９号公報に記載されているベンゾトリアゾール系の紫外線吸収剤、あるいは同８−２３９５０９号公報に記載されている紫外線吸収剤も添加することができる。その他、公知の紫外線吸収剤を添加しても良い。これら紫外線吸収剤は、セルロースアシレートに対して０．００１〜５重量％を含むようにドープ中に混合することが望ましい。例えば、特開平８−２９６１９号公報に記載されているベンゾトリアゾール系の紫外線吸収剤、あるいは同８−２３９５０９号公報に記載されている紫外線吸収剤も添加することができる。
【０１１４】
好ましい紫外線防止剤として、２，６−ジ−ｔｅｒｔ−ブチル−ｐ−クレゾール、ペンタエリスリチル−テトラキス［３−（３，５−ジ−ｔｅｒｔ−ブチル−４−ヒドロキシフェニル）プロピオネート］、トリエチレングリコール−ビス［３−（３−ｔｅｒｔ−ブチル−５−メチル−４−ヒドロキシフェニル）プロピオネート］、１，６−ヘキサンジオール−ビス［３−（３，５−ジ―ｔｅｒｔ―ブチル−４−ヒドロキシフェニル）プロピオネート］、２，４−ビス−（ｎ−オクチルチオ）−６−（４−ヒドロキシ−３，５−ジ−ｔｅｒｔ−ブチルアニリノ）−１，３，５−トリアジン、２，２−チオ−ジエチレンビス［３−（３，５−ジ−ｔｅｒｔ−ブチル−４−ヒドロキシフェニル）プロピオネート］、オクタデシル−３−（３，５−ジ−ｔｅｒｔ−ブチル−４−ヒドロキシフェニル）プロピオネート、Ｎ，Ｎ´−ヘキサメチレンビス（３，５−ジ―ｔｅｒｔ−ブチル−４−ヒドロキシ−ヒドロシンナミド）、１，３，５−トリメチル−２，４，６−トリス（３，５―ジ―ｔｅｒｔ−ブチル−４−ヒドロキシベンジル）ベンゼン、トリス−（３，５−ジ―ｔｅｒｔ−ブチル−４−ヒドロキシベンジル）−イソシアヌレイトなどが挙げられる。特に、２，６―ジ―ｔｅｒｔ−ブチル−ｐ−クレゾール、ペンタエリスリチル−テトラキス［３−（３，５―ジ―ｔｅｒｔ−ブチル−４−ヒドロキシフェニル）プロピオネート］、トリエチレングリコール−ビス［３−（３−ｔｅｒｔ−ブチル−５−メチル−４−ヒドロキシフェニル）プロピオネート］が最も好ましい。また例えば、Ｎ，Ｎ´−ビス［３−（３，５−ジ―ｔｅｒｔ−ブチル−４−ヒドロキシフェニル）プロピオニル］ヒドラジンなどのヒドラジン系化合物の金属不活性剤やトリス（２，４−ジ―ｔｅｒｔ−ブチルフェニル）フォスファイトなどのリン系加工安定剤を併用してもよい。これらの化合物の添加量は、セルローストリアセテートに対して重量割合で１ｐｐｍ〜１．０％が好ましく、１０〜１０００ｐｐｍが更に好ましい。
【０１１５】
（離型剤）
また、ドープには、離型操作を容易にするための離型剤を添加することもできる。離型剤には、高融点のワックス類、高級脂肪酸およびその塩やエステル類、シリコーン油、ポリビニルアルコール、低分子量ポリエチレン、植物性タンパク質誘導体などが挙げられるが、これらに限定されない。離型剤の添加量は、フィルムの表面の光沢や平滑性に影響を及ぼすため、セルローストリアセテートに対して０．００１〜２重量％含有していることが好ましい。
【０１１６】
（フッ素系界面活性剤）
ドープには、フッ素系界面活性剤を添加することもできる。フッ素系界面活性剤は、フルオロカーボン鎖を疎水基とする界面活性剤であり、表面張力を著しく低下させるため有機溶媒中での塗布剤や、帯電防止剤として用いられる。フッ素系界面活性剤としては、Ｃ_８Ｆ_１７ＣＨ_２ＣＨ_２Ｏ―　（ＣＨ_２ＣＨ_２Ｏ）_１０−ＯＳＯ_３Ｎａ、Ｃ_８Ｆ_１７ＳＯ_２Ｎ（Ｃ_３Ｈ_７）（ＣＨ_２ＣＨ_２Ｏ）_１６−Ｈ、Ｃ_８Ｆ_１７ＳＯ_２Ｎ（Ｃ_３Ｈ_７）ＣＨ_２ＣＯＯＫ、Ｃ_７Ｆ_１５ＣＯＯＮＨ_４、Ｃ_８Ｆ_１７ＳＯ_２Ｎ（Ｃ_３Ｈ_７）（ＣＨ_２ＣＨ_２Ｏ）_４−（ＣＨ_２）_４−ＳＯ_３Ｎａ、Ｃ_８Ｆ_１７ＳＯ_２Ｎ（Ｃ_３Ｈ_７）−（ＣＨ_２）_３−Ｎ^＋（ＣＨ_３）_３・Ｉ⁻、Ｃ_８Ｆ_１７ＳＯ_２Ｎ（Ｃ_３Ｈ_７）ＣＨ_２ＣＨ_２ＣＨ_２Ｎ^＋（ＣＨ_３）_２−ＣＨ_２ＣＯＯ⁻、Ｃ_８Ｆ_１７ＣＨ_２ＣＨ_２Ｏ（ＣＨ_２ＣＨ_２Ｏ）_１６−Ｈ、Ｃ_８Ｆ_１７ＣＨ_２ＣＨ_２Ｏ（ＣＨ_２）_３−Ｎ^＋（ＣＨ_３）_３・Ｉ⁻、Ｈ（ＣＦ_２）_８−ＣＨ_２ＣＨ_２ＯＣＯＣＨ_２ＣＨ（ＳＯ_３）ＣＯＯＣＨ_２ＣＨ_２ＣＨ_２ＣＨ_２−（ＣＦ_２）_８−Ｈ、Ｈ（ＣＦ_２）_６ＣＨ_２ＣＨ_２Ｏ（ＣＨ_２ＣＨ_２Ｏ）_１６−Ｈ、Ｈ（ＣＦ_２）_８ＣＨ_２ＣＨ_２Ｏ（ＣＨ_２）_３−Ｎ^＋（ＣＨ_３）_３・Ｉ⁻、Ｈ（ＣＦ_２）_８ＣＨ_２ＣＨ_２ＯＣＯＣＨ_２ＣＨ（ＳＯ_３）ＣＯＯＣＨ_２ＣＨ_２ＣＨ_２ＣＨ_２Ｃ_８Ｆ_１７、Ｃ_９Ｆ_１７−Ｃ_６Ｈ_４−ＳＯ_２Ｎ（Ｃ_３Ｈ_７）（ＣＨ_２ＣＨ_２Ｏ）_１６−Ｈ、Ｃ_９Ｆ_１７−Ｃ_６Ｈ_４−ＣＳＯ_２Ｎ（Ｃ_３Ｈ_７）−（ＣＨ_２）_３−Ｎ^＋（ＣＨ_３）_３・Ｉ⁻などが挙げられるが、これらに限定される訳ではない。フッ素系界面活性剤の添加量は、セルローストリアセテートに対して０．００２〜２重量％含有していることが好ましい。
【０１１７】
（その他添加剤）
また、ドープには、必要に応じて更に種々の添加剤を溶液の調整前から調整後のいずれかの段階で添加してもよい。カルシウム、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、油剤などである。
【０１１８】
（マット剤等）
本発明のセルロースアシレート溶液に、微粒子のマット剤を含有させることが好ましく、製膜した後の偏光板用保護フィルムとしてのセルロースアシレートフィルムに、微粒子のマット剤が存在することによって、適度の滑りと耐擦り傷が付与させる。微粒子のマット剤はセルロースアシレート塗布液中に混合・分散して用いる。微粒子のマット剤としては、例えば二酸化ケイ素、二酸化チタン、酸化アルミニウム、酸化ジルコニウム、炭酸カルシウム、カオリン、タルク、焼成ケイ酸カルシウム、水和ケイ酸カルシウム、ケイ酸アルミニウム、ケイ酸マグネシウム、リン酸カルシウム等の無機微粒子や架橋高分子微粒子を含有させることが好ましい。中でも二酸化ケイ素がフィルムのヘイズを小さく出来るので好ましい。微粒子の２次粒子の平均粒径は０．０１〜１．０μｍの範囲で、その含有量はセルロースアシレートに対して０．００５〜０．３質量％が好ましい。二酸化ケイ素のような微粒子には有機物、特にメチル基を有する化合物により表面処理されている場合が多いが、このようなものはフィルムのヘイズを低下出来るため本発明においては好ましい。表面処理で好ましい有機物としては、ハロシラン類、アルコキシシラン類（特にメトキシシラン）、シラザン、シロキサンなどがあげられる。微粒子の平均粒径が大きい方がマット効果は大きく、反対に平均粒径の小さい方は透明性に優れるため、好ましい微粒子の一次粒子の平均粒径は５〜５０ｎｍで、より好ましくは７〜１４ｎｍである。これらの微粒子はセルロースアシレートフィルム中では、通常、凝集体として存在しセルロースアシレートフィルム表面に０．０１〜１．０μｍの凹凸を生成させることが好ましい。二酸化ケイ素の微粒子としてはアエロジル（株）製のＡＥＲＯＳＩＬ　　２００、２００Ｖ、３００、Ｒ９７２、Ｒ９７２Ｖ、Ｒ９７４、Ｒ２０２、Ｒ８１２，ＯＸ５０、ＴＴ６００等を挙げることが出来、好ましくはＡＥＲＯＳＩＬ　　Ｒ９７２、Ｒ９７２Ｖ、Ｒ９７４、Ｒ２０２、Ｒ８１２である。これらのマット剤は２種以上併用してもよい。２種以上併用する場合、任意の割合で混合して使用することが出来る。この場合、平均粒径や材質の異なるマット剤、例えばＡＥＲＯＳＩＬ２００ＶとＲ９７２Ｖを質量比で０．１：９９．９〜９９．９〜０．１の範囲で使用出来る。
【０１１９】
更に、本発明のセルロースアシレート溶液中には、酸化防止剤を含有させることが好ましく、酸化防止剤としては、ヒンダードフェノール系の化合物が好ましく用いられ、２，６−ジ−ｔ−ブチル−ｐ−クレゾール、ペンタエリスリチル−テトラキス〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート〕、トリエチレングリコール−ビス〔３−（３−ｔ−ブチル−５−メチル−４−ヒドロキシフェニル）プロピオネート〕、１，６−ヘキサンジオール−ビス〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート〕、２，４−ビス−（ｎ−オクチルチオ）−６−（４−ヒドロキシ−３，５−ジ−ｔ−ブチルアニリノ）−１，３，５−トリアジン、２，２−チオ−ジエチレンビス〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート〕、オクタデシル−３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート、１，３，５−トリメチル−２，４，６−トリス（３，５−ジ−ｔ−ブチル−４−ヒドロキシベンジル）ベンゼン、トリス−（３，５−ジ−ｔ−ブチル−４−ヒドロキシベンジル）−イソシアヌレイト等を挙げることが出来る。特に２，６−ジ−ｔ−ブチル−ｐ−クレゾール、ペンタエリスリチル−テトラキス〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオネート〕、トリエチレングリコール−ビス〔３−（３−ｔ−ブチル−５−メチル−４−ヒドロキシフェニル）プロピオネート〕が好ましい。また例えば、　Ｎ，Ｎ′−ビス〔３−（３，５−ジ−ｔ−ブチル−４−ヒドロキシフェニル）プロピオニル〕ヒドラジン等のヒドラジン系の金属不活性剤やトリス（２，４−ジ−ｔ−ブチルフェニル）フォスファイト等のリン系加工安定剤を併用してもよい。これらの化合物の添加量は、セルロースアシレートに対して質量割合で１ｐｐｍ〜１．０％が好ましく、１０〜１０００ｐｐｍが更に好ましい。
【０１２０】
（剥離層）
本発明においては、回収可能なセルロースアシレート層と回収が難しいセルロースアシレート層との間に剥離層を有することが好ましい。
剥離層はモノマーや重合性化合物を有するセルロースアシレートフィルムをスリットしてセルロースアシレートフィルム半製品を製造する際に発生するセルロースアシレートフィルム屑を再利用する際に、再使用可能なセルロースアシレートと再使用が困難なモノマー及び重合性化合物の重合物を分別し、廃棄物量を減ずることができ、好ましい。
剥離層は、分離溶剤（セルロースエステル層とモノマーや重合性化合物塗布層とを分離する際に使用する溶剤）に対する溶解性がセルロースエステル層と異なるポリマーで形成されている。このポリマーは、分離溶剤によって決定されるが、例えば、セルロースアセテート、セルロースプロピオネート、セルロースアセテートプロピオネート、セルロースブチレート、セルロースアセテートブチレート、ポリアミド、ポリカーボネート、ポリスルホン、ポリエーテルスルホン、ポリアリレート、ポリフェニレンオキサイドがある。特開平５−９３９７６号に記載されているような、セルロースアシレートのアシレート置換率の低い素材は、本発明のセルロースアシレートとはアセトン／メタノール（７０／３０）に対する溶解性が異なり、好ましい一例である。
これらは、単独でも、必要によりブレンドして用いてもよい。これらのポリマーは、分子量が１万以上のものを使用可能であるが、通常は２万から８０万のものを使用する。
また、ハロゲン化銀写真感光材料に用いられるゼラチンを主成分とし、ハロゲン化銀やカプラーなど素材を除いたゼラチン層も好ましい一例としてあげられる。
【０１２１】
剥離層の厚さは特に制限されないが、０．２〜１０μｍの範囲が好ましい。剥離層は、剥離層用ドープを流延することあるいは、剥離層用塗布液を塗布することにより形成される。この剥離層用ドープは、主として、上述したポリマーと有機溶剤とで構成されている。有機溶剤は、各ポリマーによって異なるが、隣接する層のドープと接したときに相分離や白濁しないような親和性を有することが必要で、例えばジクロロメタン、クロロホルム、テトラクロロエチレン、ジメチルアセトアミド、アセトン、メチルエチルケトン、メタノール、エタノールがある。剥離層用ドープ中のポリマーの量は、３〜５０重量％が好ましく、８〜２７重量％が特に好ましい。
【０１２２】
剥離層の分離は、剥離層の素材に応じて選択することができ、分離方法は分離溶剤に浸漬することにより分離される。こうして分離されたセルロースエステル層は通常の精製工程で処理でき、再生原料として使用できる。セルロースエステル層とモノマー重合層の分離には、比重差を利用した沈降分離、遠心分離等、公知の一般的な分離法を使用することができる。
【０１２３】
（セルロースアシレート積層フィルムの表面処理）
本発明においては、表面処理を行うことによって、セルロースアシレートフィルムと各機能層（例えば、剥離層、下塗層およびバック層）との接着の向上を達成することができる。例えばグロー放電処理、紫外線照射処理、コロナ処理、火炎処理、酸またはアルカリ処理を用いることができる。ここでいうグロー放電処理とは、１０−３〜２０Ｔｏｒｒの低圧ガス下でおこる低温プラズマでもよく、更にまた大気圧下でのプラズマ処理も好ましい。プラズマ励起性気体とは上記のような条件においてプラズマ励起される気体をいい、アルゴン、ヘリウム、ネオン、クリプトン、キセノン、窒素、二酸化炭素、テトラフルオロメタンの様なフロン類及びそれらの混合物などがあげられる。これらについては、詳細が発明協会公開技報（公技番号　２００１−１７４５、２００１年３月１５日発行、発明協会）にて３０頁〜３２頁に詳細に記載されている。なお、近年注目されている大気圧でのプラズマ処理は、例えば１０〜１０００Ｋｅｖ下で２０〜５００Ｋｇｙの照射エネルギーが用いられ、より好ましくは３０〜５００Ｋｅｖ下で２０〜３００Ｋｇｙの照射エネルギーが用いられる。これらの中でも特に好ましくは、アルカリ鹸化処理でありセルロースアシレートフィルムの表面処理としては極めて有効である。
【０１２４】
アルカリ鹸化処理は、鹸化液を塗布することで行ことも好ましい。塗布方法としては、ディップコーティング法、カーテンコーティング法、エクストルージョンコーティング法、バーコーティング法およびＥ型塗布法を挙げることができる。アルカリ鹸化処理塗布液の溶媒は、鹸化液の透明支持体に対して塗布するために濡れ性が良く、また鹸化液溶媒によって透明支持体表面に凹凸を形成させずに、面状を良好なまま保つ溶媒を選択することが好ましい。具体的には、アルコール系溶媒が好ましく、イソプロピルアルコールが特に好ましい。また、界面活性剤の水溶液を溶媒として使用することもできる。アルカリ鹸化塗布液のアルカリは、上記溶媒に溶解するアルカリが好ましく、ＫＯＨ、ＮａＯＨがさらに好ましい。鹸化塗布液のｐＨは１０以上が好ましく、１２以上がさらに好ましい。アルカリ鹸化時の反応条件は、室温で１秒以上５分以下が好ましく、２秒以上１分以下がさらに好ましく、３秒以上３０秒以下が特に好ましい。アルカリ鹸化反応後、鹸化液塗布面を水洗あるいは酸で洗浄したあと水洗することが好ましい。また、塗布式鹸化処理と後述の配向膜解塗設を、連続して行うことができ、工程数を減少できる。更に、本発明で得られるセルロースアシレートフィルムは、アルカリ処理を浸漬法で実施してもよい。すなわち、アルカリ処理浴、水洗浴、酸処理浴更に水洗浴、場合によりリンス浴などを連続的あるいは間歇的に配置して、表面処理を実施できる。この場合各溶液は、塗布方式で使用される対応する溶液と内容としては、同一の組成である。
【０１２５】
（セルロースアシレート積層フィルムの用途）
本発明で作製されたセルロースアシレート積層フィルムの用途についてまず簡単に述べる。本発明の光学フィルムは特に偏光板保護フィルム用として有用である。偏光板保護フィルムとして用いる場合、偏光板の作製方法は特に限定されず、一般的な方法で作製することができる。得られたセルロースアシレートフィルムをアルカリ処理し、ポリビニルアルコールフィルムを沃素溶液中に浸漬延伸して作製した偏光子の両面に完全ケン化ポリビニルアルコール水溶液を用いて貼り合わせる方法がある。アルカリ処理の代わりに特開平６−９４９１５号、特開平６−１１８２３２号に記載されているような易接着加工を施してもよい。保護フィルム処理面と偏光子を貼り合わせるのに使用される接着剤としては、例えば、ポリビニルアルコール、ポリビニルブチラール等のポリビニルアルコール系接着剤や、ブチルアクリレート等のビニル系ラテックス等が挙げられる。偏光板は偏光子及びその両面を保護する保護フィルムで構成されており、更に該偏光板の一方の面にプロテクトフィルムを、反対面にセパレートフィルムを貼合して構成される。プロテクトフィルム及びセパレートフィルムは偏光板出荷時、製品検査時等において偏光板を保護する目的で用いられる。この場合、プロテクトフィルムは、偏光板の表面を保護する目的で貼合され、偏光板を液晶板へ貼合する面の反対面側に用いられる。又、セパレートフィルムは液晶板へ貼合する接着層をカバーする目的で用いられ、偏光板を液晶板へ貼合する面側に用いられる。液晶表示装置には通常２枚の偏光板の間に液晶を含む基板が配置されているが、本発明の光学フィルムを適用した偏光板保護フィルムはどの部位に配置しても優れた表示性が得られる。特に液晶表示装置の表示側最表面の偏光板保護フィルムには透明ハードコート層、防眩層、反射防止層等が設けられるため、該偏光板保護フィルムをこの部分に用いることが特に好ましい。
【０１２６】
本発明のセルロースアシレート積層フィルム（本発明において単に「セルロースアシレートフィルム」ともいう。）は、様々な用途で用いることができ、液晶表示装置の光学補償シートとして用いると特に効果がある。本発明のセルロースアシレートフィルムは、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）および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。本発明のセルロースアシレートフィルムを、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。本発明のセルロースアシレートフィルムを、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（△ｎ）とセルギャップ（ｄ）との積（△ｎｄ）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。本発明のセルロースアシレートフィルムは、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特に有利に用いられる。本発明のセルロースアシレートフィルムは、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も有利に用いられる。
【０１２７】
（光学補償シート）
本発明のセルロースアシレートフィルムは、ＴＮ型、ＳＴＮ型、ＨＡＮ型、ＧＨ（Ｇｕｅｓｔ−Ｈｏｓｔ）型の反射型液晶表示装置の光学補償シートとしても有利に用いられる。これらの表示モードは古くから良く知られている。ＴＮ型反射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。反射型液晶表示装置に用いる光学補償シートについては、ＷＯ００−６５３８４号に記載がある。本発明のセルロースアシレートフィルムは、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も有利に用いられる。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）他の論文（Ｋｕｍｅ　ｅｔ　ａｌ．，　ＳＩＤ　９８　Ｄｉｇｅｓｔ　１０８９　（１９９８））に記載がある。以上述べてきたこれらの詳細なセルロースアシレートフィルムの用途は発明協会公開技報（公技番号　２００１−１７４５、２００１年３月１５日発行、発明協会）にて４５頁〜５９頁に詳細に記載されている。
【０１２８】
【実施例】
以下に本発明を実施例により具体的に説明するが、本発明はこれらに限定されない。
【０１２９】
＜セルローストリアセテート溶液の仕込み＞
表１に示す処方で、攪拌羽根を有するステンレス性溶解タンクに、添加剤を加えた混合溶媒によく攪拌しつつ、セルローストリアセテート粉体（平均サイズ２ｍｍ）を徐々に添加し、仕込んだ。添加後、タンクを減圧にして１時間分散し、２５℃加圧状態で２時間攪拌しセルローストリアセテートを膨潤させた。なお、溶媒である酢酸メチルとエタノール、アセトン、メタノール、ブタノール及びジクロロメタンは、すべてその含水率が０．２質量％以下のものを利用した。
【０１３０】
【表１】

【０１３１】
＜セルローストリアセテートドープ溶液の調整（冷却溶解）＞
上述したセルローストリアセテート溶液をスクリュー押し出し機で送液して、−７０℃で１０分間となるように冷却部分を通過させた。冷却は冷凍機で冷却した−８０℃の冷媒（３Ｍ社製，『フロリナート』）を用いて実施した。そして、冷却により得られた溶液は、静止型混合器を設置した熱交換器により１２０℃まで温度を上昇させ、３分間保持した後冷却し５０℃としてステンレス製の容器に移送し、５０℃で２時間撹拌し脱泡を行った。この後、絶対濾過精度０．０１ｍｍの濾紙（東洋濾紙（株）製，『＃６３』）で濾過し、さらに、絶対濾過精度０．００２５ｍｍの濾紙（ポール社製，『ＦＨ　０２５』）にて濾過し、セルローストリアセテートドープ溶液を調整した。
【０１３２】
＜セルローストリアセテートフィルムの作製及び切除＞
表２に示すようにろ過したドープを無限移行する無端のステンレスベルトを有するバンド流延機にて流延幅が１０００ｍｍとなるように流延した。流延バンドは、ステンレススチール製で厚さ１．５ｍｍのものを用いた。流延バンドと回転ドラムとの接触時間が非接触時間の１２％であった。流延部のステンレスベルト支持体の温度は表２に示した。バンド流延機に設置した紫外線照射ブース内に１５℃の乾燥窒素を導入し、酸素濃度をコントロールした。表２に示す量の紫外線を照射し光重合させた。ブースを出たドープ膜を８０℃の乾燥風で３分間乾燥し、残留溶媒量５０％でフィルムウェブを剥ぎ取り、９０〜１１５℃で乾燥し、次にロール乾燥装置で１１０〜１３０℃で乾燥し、乾燥されたウェブを残留溶媒量を０．２質量％で巻き取り、６０μｍのセルロースアセテートフィルムを得た。得られた試料は端から２〜１０ｍｍの部分に高さ１００μｍのナーリングを実施し、長さ５００ｍロール状に巻き取った。
また、流延ダイの先端部と流延バンドとの距離の変動は１５０μｍ以下とした。そして、実験中で流延バンド上の発泡現象とフィルムの剥ぎ取り状態について観察し、下記に示す評価を行なった。
【０１３３】
＜偏光子の作製＞
ＰＶＡフィルムをヨウ素２．０ｇ／Ｌ、ヨウ化カリウム４．０ｇ／Ｌの水溶液に２５℃にて２４０秒浸漬し、さらにホウ酸１０ｇ／Ｌの水溶液に２５℃にて６０秒浸漬後、テンター延伸機に導入し、５．３倍に延伸し、以降幅を一定に保ち、収縮させながら８０℃雰囲気で乾燥させた後テンターから離脱して巻き取った。延伸開始前のＰＶＡフィルムの含水率は３１％で、乾燥後の含水率は１．５％であった。
左右のテンタークリップの搬送速度差は、０．０５％未満であった。テンター出口におけるシワ、フィルム変形は観察されなかった。
得られた偏光子の５５０ｎｍにおける透過率４３．７％、偏光度９９．９７％であった。
【０１３４】
＜偏光板の作製＞
製膜したセルロースアセテートフィルムを５５℃の１．５ＮＮａＯＨ水溶液に１分間浸漬して両面を鹸化した後、希硫酸および水で十分洗浄し、乾燥後それぞれのセルローストリアセテート側にポリビニルアルコール系粘着材を約３０μの厚みに塗布し、上記偏光子の両側に貼り合わせ、さらに８０℃で乾燥して偏光板を作成した。
この偏光板を８０℃、９０％ＲＨの雰囲気下で５００時間暴露した。いずれの本発明においても偏光度は９９％以上であり、十分な耐久性が認められた。
【０１３５】
＜評価＞
（発泡現象）
流延バンド上で乾燥中の発泡現象を観察した。
○：流延バンド上で発泡現象がなかった。
×：流延バンド上で発泡現象が認められた。
【０１３６】
（剥離状態）
流延バンドから剥ぎ取った後の状態を観察した。
○：流延バンド上にドープの剥ぎ残りがなかった。
△：流延バンドのエッジ部にドープの付着物がわずかに認められたが成長しない状態であった。
×：剥ぎ残りが成長した状態であった。
【０１３７】
（ヘイズ）
セルロースアセテートフィルムのヘイズは、日本電色工業（株）製、１００１ＤＰ型を用いて、９０℃／８０％の高温高湿下で５００時間保管しその前後で調べた。
【０１３８】
（表面粗さ（Ｒａ））
表面粗さ（中心線平均粗さ）の算出原理は、ＪＩＳ−Ｂ０６０１「表面粗さ」に規定されている中心線平均粗さに準じており、測定は、小坂研究所製、万能表面形状測定器、ＳＥ−３Ｆを用いて行った。
【０１３９】
（偏光度）偏光板の偏光度は、分光光度計により可視領域における並行透過率Ｙｐ、直行透過率Ｙｃを求め、次式に基づき偏光度Ｐを決定した。
Ｐ＝（（Ｙｐ−Ｙｃ）／（Ｙｐ＋Ｙｃ））^１／２
【０１４０】
＜結果＞
前述した、発泡現象、剥離状態のほか、フィルムのヘイズ及び表面粗さを測定した。結果を表２に示した。
表２から本発明は発泡現象を起こさず、剥離状態も良好であり、表面粗さ及びヘイズも良好であることが確認された。特に高温高湿経時後のヘイズは悪化せず、低分子物の析出も認められないことが分かった。一方、紫外線照射ブース内の酸素濃度の高い比較例１０１、１０６は剥離状態が悪く、表面粗さ、ヘイズを悪化することが確認され、ドープ膜面温度がドープ主溶剤の沸点−３℃より高い比較例１０３、１０５は発泡現象を生じ、剥離状態も悪く、表面粗さ、ヘイズを悪化することが分かり、ドープ膜面温度が幅方向に均一でない比較例１０２、１０４は剥離状態がやや悪く、表面粗さ、ヘイズの性能が本発明よりも劣ることが理解できる。
また、照射量分布が均一でない比較例１０７や照射時間が本発明の請求範囲外である比較例１０８では剥離状態が悪く表面粗さ、ヘイズの性能が出ないことが分かる。
さらに、本発明の重合性モノマーと光重合開始剤を含有しない比較例１０９、１１０では、高温高湿経時のヘイズが悪化して、添加剤が泣き出しやすい結果が再現された。
【０１４１】
【表２】

【０１４２】
【発明の効果】
本発明によれば、種々の要求特性を満足させる添加剤の泣き出しがなく、ヘイズ増加が少なく、耐久性悪化も無く、かつ材料の有効利用可能なセルロースアシレートフィルム及び偏光板を得ることができる。
【０１４３】
【図面の簡単な説明】
【図１】本発明による流延製膜方法を実施する流延製膜ラインの一実施形態の概略図である。
【符号の説明】
１１　ミキシングタンク
１２　送液ポンプ
１３　フィルタ
１４　流延ダイ
１５　流延バンド
１６　流延部側回転ドラム
１７　非流延部側回転ドラム
１８　ガイドロール
１９　剥ぎ取りロール
２０　ガイドロール
２１　巻取りロール
２２　乾燥部
２３　フィルム[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cellulose acylate film particularly suitable for optical applications and a method for producing the same. Furthermore, it is related with the polarizing plate using a cellulose acylate film.
[0002]
[Prior art]
In recent years, the demand for thin transparent plastic films has increased as protective films for polarizing plates, optical compensation films such as retardation plates, plastic substrates, photographic supports, moving cells and optical filters, and optical materials such as OHP films. doing. In particular, liquid crystal displays have recently improved in quality, such as TN, STN, and TFT, and are lightweight and have excellent portability, so personal computers, word processors, portable terminals, TVs, and digital still cameras and movie cameras In this liquid crystal display, a polarizing plate is essential for image display. Along with the improvement in the quality of liquid crystal displays, an improvement in the quality of the polarizing plate is required, and at the same time, a transparent plastic film that is a protective film for the polarizing plate is also required to have a higher quality.
[0003]
For optical films such as protective films for polarizing plates, high transparency, low optical anisotropy, flatness, easy surface treatment, high durability (dimensional stability, moisture and heat resistance, Water resistance), no foreign matter in the film and on the film surface, no scratches on the surface or difficult to stick (scratch resistance), moderate film rigidity (handleability), moderate water permeability, etc. It is necessary to have characteristics.
[0004]
Examples of plastic films having these characteristics include films made of cellulose acylate, norbornene resin, acrylic resin, polyarylate resin, polycarbonate resin, etc., but cellulose acylate is mainly used from the viewpoint of productivity and material price. Has been. In particular, a film of cellulose triacetate is particularly advantageously used for optical applications because it has extremely high transparency, low optical anisotropy, and low retardation.
[0005]
As a method for forming these plastic films, various film forming techniques such as a solution film forming method, a melt film forming method and a rolling method can be used, but in order to obtain good flatness and low optical anisotropy. For this, the solution casting method is particularly suitable. The solution casting method involves dissolving raw material flakes in a solvent and adding various additives such as a plasticizer, an ultraviolet absorber, a deterioration preventing agent, a slipping agent and a peeling accelerator as necessary (“ The dope is called “dope”) on a support composed of a horizontal endless metal belt or a rotating drum by a dope supply means (referred to as “die”) and then dried to some extent on the support. Then, the film to which rigidity has been imparted is peeled off from the support, and then the solvent is removed by passing through the drying section by various conveying means.
[0006]
However, in cellulose acylate, additives such as added plasticizers, UV absorbers, deterioration inhibitors, slipping agents, peeling accelerators, etc., precipitate during the manufacturing process and become defective, and are exposed to high temperatures and high humidity. In some cases, this causes a failure such as precipitation and a decrease in transmittance. Furthermore, in order to eliminate the above-mentioned condensation that causes defects, it is necessary to stop the film production line and clean it over time, which not only reduces productivity, but also dirt attached to the film, etc. All of these factors have increased costs, such as inspections to check for defects, removal of defective parts, and a decrease in yield due to removal of defective parts. Therefore, as a countermeasure against this failure, in JP-A-2002-20410, a polymerizable monomer having an effect as an additive is added to a cellulose acylate dope, polymerized by light irradiation after casting the solution, A method for preventing crying is disclosed.
[0007]
However, in the method described in the publication, foaming from the dope film occurs due to ultraviolet irradiation, the peelability of the dope film from the metal support is poor, the trouble that the film is cut at the time of web handling occurs, and the flatness is conventional. It was revealed that the cellulose acylate film had a drawback that it was worse and haze was higher.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for producing a cellulose acylate film which is excellent in the peelability of a dope film, does not cause trouble that the film is cut during web handling, and does not cause the additive to cry (precipitate). . Furthermore, it is providing the cellulose acylate film excellent in optical characteristics, such as planarity and transparency (low haze). In addition, it is to provide a polarizing plate.
[0009]
[Means for Solving the Problems]
(1) A cellulose acylate dope solution containing an ethylenically unsaturated monomer and / or a functional group-containing ethylenically unsaturated monomer and a photopolymerization initiator is cast on a casting support from a casting die. A method for producing a cellulose acylate film, characterized in that the oxygen concentration in the ultraviolet irradiation booth when irradiating the dope solution on the casting support with ultraviolet rays is 10% or less,
(2) The temperature of the dope film in the ultraviolet irradiation booth when irradiating the dope solution on the casting support with ultraviolet rays is 3 ° C. or more lower than the boiling point of the dope main solvent. A method for producing a cellulose acylate film of
(3) The temperature of the dope film in the ultraviolet irradiation booth when irradiating the dope solution on the casting support with ultraviolet rays is uniform in the width direction and not more than 5 ° C. away from the temperature at the center. (1) or the method for producing a cellulose acylate film according to (2),
(4) The ultraviolet irradiation amount at the time of irradiating the dope solution on the casting support with ultraviolet rays is uniform in the width direction and not more than 20% from the central portion irradiation amount (1) to ( 3) The method for producing a cellulose acylate film according to any one of
(5) The cellulose according to any one of (1) to (4), wherein an ultraviolet irradiation time when the dope solution on the casting support is irradiated with ultraviolet rays is 1 to 300 seconds. Production method of acylate film,
(6) The method for producing a cellulose acylate film according to any one of (1) to (5), wherein the ethylenically unsaturated monomer is mainly a vinyl ester,
(7) The method for producing a cellulose acylate film according to any one of (1) to (6), comprising an ethylenically unsaturated monomer having 2 to 3 ethylenically unsaturated groups,
(8) The method for producing a cellulose acylate film according to any one of (1) to (7), wherein the functional group is an ultraviolet absorbing group and / or an antistatic group,
[0010]
(9) Cellulose acylate containing a compound having a 3-membered or 4-membered cyclic ether group and / or a compound having a 3-membered or 4-membered cyclic ether group and an ultraviolet absorbing group and a photopolymerization initiator In a method for producing a film by casting a dope solution on a casting support from a casting die, the oxygen concentration in the ultraviolet irradiation booth when the dope solution on the casting support is irradiated with ultraviolet rays is 20%. A method for producing a cellulose acylate film, characterized by:
(10) The temperature of the dope film in the ultraviolet irradiation booth when irradiating the dope solution on the casting support with ultraviolet rays is 3 ° C. or more lower than the boiling point of the dope main solvent. A method for producing a cellulose acylate film of
(11) The temperature of the dope film in the ultraviolet irradiation booth when irradiating the dope solution on the casting support with ultraviolet rays is uniform in the width direction and not more than 5 ° C. away from the temperature at the center. (9) or the method for producing a cellulose acylate film according to (10),
(12) The ultraviolet ray irradiation amount when irradiating the dope solution on the casting support with ultraviolet rays is uniform in the width direction and not more than 20% away from the central portion irradiation amount (9) to ( 11) The method for producing a cellulose acylate film according to any one of
(13) The cellulose according to any one of (9) to (12), wherein an ultraviolet irradiation time for irradiating the dope solution on the casting support with ultraviolet rays is 1 to 300 seconds. Production method of acylate film,
(14) The method for producing a cellulose acylate film according to any one of (1) to (13), wherein the outermost cellulose acylate solution contains fine particles.
(15) The method for producing a cellulose acylate film according to (14), wherein the fine particles are composed of a compound containing silicon oxide having a methyl group on the surface,
[0011]
(16) In the method for producing a cellulose acylate film according to any one of (1) to (15), the cellulose acylate solution is cast on an endless metal support that moves infinitely in a solution casting film forming apparatus. And then, after the drying of the web by the drying device is completed, the method for producing a cellulose acylate film, wherein the web is irradiated with ultraviolet rays,
(17) The method for producing a cellulose acylate film according to (16), wherein the cellulose acylate solution is irradiated with ultraviolet rays after being cast on an endless metal support that moves indefinitely until peeling.
[0012]
(18) A cellulose acylate film formed by the method for producing a cellulose acylate film according to any one of (1) to (17),
(19) A polarizing plate using the cellulose acylate film described in (18).
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
In the present invention, a cellulose acylate film solution added with a specific monomer or polymerizable compound capable of exhibiting the same effect can be used instead of a conventional additive which can be added to a conventional cellulose acylate film solution and become a crying substance. The film is obtained by photopolymerization under the conditions described in detail below to prevent the additive from crying out.
[0014]
(Casting of cellulose acylate solution)
First, a method for producing a film using the cellulose acylate solution of the present invention will be described. For the method and equipment for producing the cellulose acylate film of the present invention, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film are used. The dope (cellulose acylate solution) prepared from the dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is sent from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations, and the dope is run endlessly from the die (slit) of the pressure die. The dry-dried dope film (also referred to as a web) is peeled off from the metal support at the peeling point cast on the metal support, and the metal support has substantially gone around.
Furthermore, both ends of the obtained web are sandwiched between clips, transported by a tenter while holding the width, dried, then transported by a roll group of a drying device to finish drying, and wound up to a predetermined length by a winder . The combination of the tenter and the roll group dryer varies depending on the purpose. In the solution casting film forming method used for silver halide photographic light-sensitive materials and functional protective films for electronic displays, in addition to the solution casting film forming apparatus, an undercoat layer, an antistatic layer, an antihalation layer, a protective layer, etc. A coating device can be added for surface processing of the film. Each of these manufacturing processes is described in detail on pages 25 to 30 in the Japan Institute of Invention Disclosure Bulletin (Public Technical Number 2001-1745, issued March 15, 2001, Japan Institute of Invention). Methods classified into body, drying, peeling and stretching can be used.
[0015]
Here, although the space temperature of a casting part is not specifically limited in this invention, It is preferable that it is -50-50 degreeC. Furthermore, it is preferable that it is -30-40 degreeC, and it is especially preferable that it is -20-30 degreeC. In particular, the cellulose acylate solution cast at a low space temperature can be cooled on the support instantly to increase the gel strength, thereby holding the film containing the organic solvent. Moreover, it can suppress the foaming which generate | occur | produces at the time of ultraviolet irradiation in this by the photopolymerization irradiation (ultraviolet irradiation) booth following this.
Furthermore, it can be peeled off from the support in a short time without evaporating the organic solvent from the cellulose acylate, and high-speed casting can be achieved. The means for cooling the space may be normal air, nitrogen, argon, helium or the like, and is not particularly limited. The humidity in that case is preferably 0 to 70% RH, and more preferably 0 to 50% RH. Moreover, in this invention, the temperature of the support body of the casting part which casts a cellulose acylate solution is -50-130 degreeC, Preferably it is -30-25 degreeC, Furthermore, it is -20-15 degreeC. In order to keep the casting part at the temperature of the present invention, it may be achieved by introducing a cooled gas into the casting part, or a cooling device may be arranged in the casting part to cool the space. At this time, it is important to take care not to attach water, and it can be carried out by a method such as using dry gas.
[0016]
The ultraviolet irradiation booth is a booth for irradiating the polymerizable monomer, which will be described later, with ultraviolet rays, and is preferably installed in a process until the drying is finished after casting, until it is peeled off from the casting drum or the casting band. It is more preferable to install between. In the ultraviolet irradiation booth, it is preferable to reduce the oxygen concentration, the amount of water, etc. in order to increase the properties of the produced film and the efficiency of ultraviolet irradiation. A preferable oxygen concentration is 20 vol% or less, more preferably 10 vol% or less, further preferably 5 vol% or less, and particularly preferably 2 vol% or less. The water content is preferably 60% RH or less as relative humidity, more preferably 50% RH or less, still more preferably 40% RH or less, and particularly preferably 30% RH or less.
In particular, in photopolymerization initiators that generate radicals, when the oxygen concentration is 10 vol% or more, the generated radicals are deactivated, the polymerization reaction does not continue, the peelability of the dope film is poor, and the film strength and haze after drying are low. Such as optical characteristics deteriorate. Further, when the water content is 60% RH or more, the peelability, film strength and optical properties are similarly deteriorated.
[0017]
The temperature in the booth is preferably 3 ° C. lower than the boiling point of the dope main solvent ((boiling point−3) ° C.) or less in advance in order to suppress temperature rise and foaming due to ultraviolet irradiation of the dope film. At (boiling point-3) ° C. or higher, foaming occurs, and peeling off is liable to occur at the time of peeling from the metal support, resulting in foreign matter adhering to the metal support. In this case, a serious defect is generated in the flatness of the film, optical characteristics such as haze are deteriorated, and there is a high possibility that a trouble that the film is cut during web handling occurs.
[0018]
Further, the temperature in the booth preferably has a small distribution in the temperature of the dope film in the width direction, and is preferably within the center temperature ± 5 ° C., more preferably within 3 ° C. in the entire width region. If the temperature difference is large, peeling unevenness occurs or the film thickness varies, resulting in poor flatness and optical characteristics.
[0019]
(Photopolymerization irradiation)
In the present invention, photopolymerization irradiation for polymerizing a monomer polymerizable compound contained in a cellulose acylate solution will be described.
Photopolymerization irradiation is performed to activate a photopolymerization initiator in order to polymerize an ethylenically unsaturated monomer or a compound having a 3-membered or 4-membered cyclic ether group, which will be described later. Radiation, gamma rays, alpha rays , Electron beams, ultraviolet rays, and the like are used. Among these, ultraviolet rays are preferably used, and ultraviolet irradiation is described below.
The ultraviolet irradiation source for photopolymerizing the ethylenically unsaturated monomer and the compound having a 3-membered or 4-membered cyclic ether group according to the present invention is a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, A xenon lamp, a carbon arc, a metal halide lamp, sunlight, etc. can be mentioned. Photopolymerization by irradiation with ultraviolet rays can be performed in air or an inert gas. However, when an ethylenically unsaturated monomer is used, a gas having a low oxygen concentration is preferable as described above, and it is 10 vol% or less. preferable. More preferably, it is 5 vol% or less, More preferably, it is 2 vol% or less.
[0020]
Irradiation intensity of ultraviolet rays to be irradiated is 1-1000 mW / cm²The degree is good and the irradiation amount is 100 to 20000 mJ / cm.²The degree is preferred.
It is preferable that the irradiation intensity / irradiation of the ultraviolet rays is uniform in the casting width direction from the viewpoint of peelability from the metal support, and 80% when the irradiation amount at the center in the casting width direction is 100%. % Irradiation amount to 120% irradiation amount is preferable. Further, it is also preferable for the purpose of preventing unevenness in optical properties such as flatness and haze and preventing curling in the width direction. The irradiation amount can be measured by installing a commercially available illuminometer / irradiance meter on a metal support and operating a casting apparatus.
[0021]
The irradiation time is preferably from 1 second to 300 seconds, and more preferably from 3 seconds to 120 seconds from the viewpoint of curing efficiency, work efficiency, casting speed, etc. of the monomer polymerizable compound. When the irradiation time is short, uneven curing tends to occur, and unevenness in optical properties such as flatness and haze occurs.
[0022]
(Swelling process)
First, the cellulose triacetate particles and a solvent are mixed, and a swelling process is performed in which the cellulose triacetate particles are swollen with the solvent. It is preferable that the temperature of a swelling process is -10-55 degreeC. Usually performed at room temperature. The ratio of cellulose triacetate and solvent is determined according to the concentration of the solution finally obtained. In general, the amount of cellulose triacetate in the mixture is preferably 5 to 30% by weight, more preferably 8 to 20% by weight, and most preferably 10 to 15% by weight. The mixture of the solvent and cellulose triacetate is preferably stirred until the cellulose triacetate is sufficiently swollen. In the swelling step, components other than the solvent and cellulose triacetate, for example, a plasticizer, a deterioration inhibitor, a dye, and an ultraviolet absorber may be added.
[0023]
(Heating process)
Next, a heating step for heating the dope to 130 ° C. or higher is performed. The heating temperature is 130 ° C. or higher, desirably 160 ° C. or higher, and most desirably 180 ° C. or higher. However, if it exceeds 250 ° C., the cellulose triacetate in the dope is decomposed, so that the quality of the film is impaired, which is not preferable. In this case, the heating rate is preferably 1 ° C./min or more, more preferably 2 ° C./min or more, further preferably 4 ° C./min or more, and more preferably 8 ° C./min or more. Most preferred. The higher the heating rate, the better. However, 10,000 ° C./second is the theoretical upper limit, 1000 ° C./second is the technical upper limit, and 100 ° C./second is the practical upper limit. The heating rate is a value obtained by dividing the difference between the temperature at the start of heating and the final heating temperature by the time from the start of heating to the final heating temperature. The heating method may be any method such as an autoclave system, a multi-tube heat exchanger, a screw extruder, and a static mixer.
[0024]
The heating time is preferably 20 seconds or longer and 4 hours or shorter. When the heating time is less than 20 seconds, insoluble materials remain in the heated and dissolved dope, and a high-quality film cannot be produced. Moreover, even when this insoluble matter is removed by filtration, it is disadvantageous because the filter life is extremely shortened. The beginning of the heating time is measured when the target temperature is reached, and the end is when the cooling starts from the target temperature. The cooling of the device may be natural cooling or forced cooling.
[0025]
(Pressure process)
In the heating step, the dope is preferably heated to a temperature equal to or higher than the boiling point at the atmospheric pressure of the solvent under a pressure adjusted so that the solution does not boil. By applying pressure, foaming of the dope can be prevented and a uniform dope can be obtained. At this time, the pressure to pressurize is determined by the relationship between the heating temperature and the boiling point of the solvent.
[0026]
(Cooling process)
Performing a cooling step of cooling the dope to −100 to −10 ° C. before the heating step is also effective for obtaining a film having good optical properties. In a system that cannot be easily dissolved at room temperature and a system that has a large amount of insoluble matter, a good dope can be prepared by using cooling, heating, or a combination of both. By cooling, the solvent can be rapidly and effectively infiltrated into cellulose triacetate, and dissolution is promoted. An effective temperature condition is −100 to −10 ° C. In the cooling step, it is desirable to use an airtight container in order to avoid moisture mixing due to condensation during cooling. Further, if the pressure is reduced during cooling, the cooling time can be shortened. In order to perform decompression, it is desirable to use a pressure resistant container. It is also effective in the present invention that this cooling step is performed after the heating step. If the dissolution is insufficient, the cooling process to the heating process may be repeated. Whether the dissolution is sufficient or not can be judged by visually observing the appearance of the solution.
[0027]
(Solution casting apparatus)
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 line using a casting band as a casting support.
[0028]
In FIG. 1, a dope is prepared by adding cellulose triacetate, an additive, a solvent and the like to a mixing tank 11. The mixing tank 11 is connected to a casting die 14 via a liquid feed pump 12 and a filter 13. A casting band 15 made of stainless steel is disposed below the casting die 14, and the casting band 15 is wound around the casting part side rotating drum 16 and the non-casting part side rotating drum 17. Further, a plurality of guide rolls 18 are provided between the casting part side rotating drum 16 and the non-casting part side rotating drum 17. The above-described ultraviolet irradiation booth (not shown) can be installed above and / or below the casting band 15 or between the stripping roll 19 and the final drying section 22, and is used to control the oxygen concentration and the dope film temperature. Can be introduced. Further, above and below the casting band 15, drying air blowing means (not shown) is provided for blowing hot air on the dope cast on the casting band 15 to dry the dope.
[0029]
When casting the dope, if the distance between the casting die 14 and the casting band 15 varies, it becomes difficult to obtain a uniform film. Therefore, in the present invention, it is preferable that the variation in the distance between the casting die 14 and the casting band 15 is 500 μm or less. More preferably, it is 200 μm or less. When the variation in distance exceeds 500 μm, the casting of the dope becomes non-uniform, and the flatness of the film after drying the dope deteriorates. The variation in distance may be measured by any known method such as providing a sensor (not shown) between the casting die 14 and the casting band 15. When the value measured by the sensor exceeds 500 μm, the film to be formed later is a defective product, so the film forming line is stopped and the installation method of the casting die 14 and the casting band 15 is changed again. There is a need to.
[0030]
When casting at a high speed, the dope film (hereinafter referred to as a ribbon) vibrates even with a slight disturbance until it reaches the casting band 15 from the outlet of the casting die 14 or if there is a large disturbance. May break. Ribbon vibration is caused by fluctuations in the distance between the tip of the casting die and the casting support, fluctuations in the flow rate of the casting dope, fluctuations in the moving speed of the casting support, and before and after the casting ribbon. This is caused by the fluctuation value of the pressure difference. The vibration of the ribbon causes periodic thickness unevenness called step unevenness in the cast film, which causes a problem in film quality. In order not to cause such quality problems, the fluctuation value of the distance between the tip of the casting die and the casting support, the fluctuation value of the flow rate of the casting dope, the casting support It is preferable that the fluctuation value of the moving speed and the fluctuation value of the pressure difference before and after the casting ribbon are both 2% or less. More preferably, it is possible to produce a high quality film by setting it to 1% or less.
[0031]
The flow rate of the casting dope is detected by a flow meter or pressure gauge, and it is a quality to monitor whether the fluctuation amount or the fluctuation value is calculated as a Fourier-transformed power spectrum and the result is within the reference value. It is desirable for management. The device for measuring the flow rate and the pressure fluctuation value preferably has a frequency response characteristic up to a sufficient range, and the frequency range is 1 Hz to 1000 Hz. When the flow rate fluctuation value exceeds 2%, it is necessary to install a buffer tank or the like that absorbs the flow rate fluctuation.
[0032]
The pressure fluctuation value before and after the casting ribbon is also detected by the pressure gauge, and it is possible to monitor whether the fluctuation amount or the calculation result like the power spectrum obtained by Fourier transforming the fluctuation value is within the reference value. It is desirable for quality control. It is preferable that the device for measuring the pressure fluctuation value has a frequency response characteristic up to a sufficient range, and the frequency range is 1 Hz to 1000 Hz. When the pressure fluctuation value exceeds 2%, it is necessary to reduce the air volume of the drying air or to form a duct in which a buffer tank is installed between the blower and the outlet.
[0033]
Changes in the moving speed of the casting support are also detected by a speed detection device, such as a rotary encoder, and the fluctuation amount or the fluctuation value is calculated as a Fourier-transformed power spectrum and the result is within the reference value. It is desirable for quality control to monitor whether or not The device for measuring the flow rate and the pressure fluctuation value preferably has a frequency response characteristic up to a sufficient range, and the frequency range is 1 Hz to 1000 Hz. When the fluctuation value of the moving speed of the casting support exceeds 2%, it is necessary to change the motor reduction ratio.
[0034]
A flow path (not shown) for circulating a heat medium is formed inside the casting part side rotating drum 16 and the non-casting part side rotating drum 17, and the heat medium is circulated through the flow path. The temperature in the width direction of the casting band 15 is made uniform.
[0035]
A stripping roll 19 is provided adjacent to the casting part side rotating drum 16 on the casting die 14 side, and a drying part 22 provided with a number of guide rolls 20 is disposed. The film 23 dried by the drying unit 22 is taken up by the take-up roll 21.
[0036]
It is necessary to supply heat energy for volatilizing the solvent in the film in the process of drying on the casting band 15 and drying while being peeled from the casting band 15 and conveyed. Examples of means for supplying thermal energy include convective heat transfer using a high-temperature gas, direct heat transfer via a drum or roll, and radiant heat transfer such as far-infrared rays or microwaves.
[0037]
In the drying on the casting band 15, conduction heat transfer from the casting band 15 itself is most desirable from the viewpoint of efficiency and uniformity, but in order to carry the dried solvent gas out of the system, the drying gas is circulated. Convective heat transfer is also performed at the same time.
[0038]
In particular, when transporting in a substantially non-contact manner using a tenter after peeling from the casting band 15, convective heat transfer using a dry gas is used for drying uniformity and efficiency and for transport of volatile solvent gas. In some cases, radiant heat transfer is also used. When heat energy is supplied to the film by these methods, the overall heat transfer coefficient is 5 to 200 kcal · m.²・ It is desirable to transmit at a heat transfer rate in the range of hr · ° C. More preferably, the overall heat transfer coefficient is 10 to 100 kcal · m.²・ Transmits at a heat transfer rate in the range of hr ・ ℃. Overall heat transfer coefficient is 200 kcal · m²・ If the temperature exceeds hr · ° C., the film is heated too quickly and foaming occurs, or the film becomes soft and difficult to convey. On the other hand, the overall heat transfer coefficient is 10 kcal · m²・ If the temperature is less than hr · ° C., the temperature change of the film is slow and the drying efficiency is lowered.
[0039]
A dope casting portion (a portion on which the cast dope is placed) and a non-casting portion (a portion on which the cast dope is not placed, that is, a portion where the surface is exposed) of the casting support; The temperature difference is preferably 5 ° C. or less, and more preferably 3 ° C. or less. When the temperature difference exceeds 5 ° C., foaming or peeling unevenness may occur at the end of the dope.
[0040]
Moreover, it is preferable that the temperature difference of the right and left of a casting support body is 10 degrees C or less, and it is more preferable that it is 5 degrees C or less. If the temperature difference between the left and right exceeds 10 ° C., foaming or peeling unevenness may occur.
[0041]
Between the cast dope and the circulating heat medium (that is, when a casting drum is used as the casting support, a casting band is used between the dope, the casting drum and the heating medium, and the casting support. The total heat transfer coefficient of the dope, casting band, rotating drum and heat medium) is 100 to 3000 kcal / m.²· Hr · ° C is preferred, 300 to 2000 kcal / m²-It is more preferable that it is hr * degreeC. The overall heat transfer coefficient can be adjusted by the flow rate of the heat medium, the thickness from the flow path to the surface of the heat medium in the casting support, and the like. Overall heat transfer coefficient is 100 kcal / m²If it is less than hr · ° C., a temperature distribution in the width direction of the casting support is generated, and it is difficult to make the temperature distribution uniform, and 3000 kcal / m²If it exceeds hr · ° C., the flow rate of the heat medium inside the drum becomes extremely high, which is not preferable because damage due to cavitation occurs.
[0042]
When a casting band is used for the casting support, the casting band immediately before the casting part can be uniformly cooled in the width direction, and the casting band other than just before the casting part can be uniformly heated in the width direction. preferable. By setting it as such a structure, it becomes possible to raise the efficiency of drying, suppressing foaming and peeling defect.
[0043]
In order to cool the casting band immediately before the casting part in the width direction and to uniformly heat the casting band other than just before the casting part in the width direction, for example, the rotating drum arranged on the casting part side is cooled. At the same time, it can be performed by heating the rotating drum arranged on the non-casting part side. At this time, the cooling heat medium temperature is preferably −10 to 30 ° C., more preferably 0 to 20 ° C., and the heating medium temperature is preferably 15 to 80 ° C., more preferably 30 to 50 ° C. If the cooling heat medium temperature is lower than −10 ° C., the solvent gas in the drying zone may condense, the water may condense or freeze, and the drum or band may corrode or the transmission efficiency may decrease. . Moreover, when it exceeds 30 degreeC, the cooling effect is not enough and there exists a possibility that foaming and peeling defect may generate | occur | produce. If the heating medium temperature is less than 15 ° C., the heating effect is not sufficient, and the drying efficiency may be reduced and peeling failure may occur. On the other hand, when the temperature exceeds 80 ° C., the temperature of the cast dope increases, which may cause foaming or defective peeling.
[0044]
The thickness between the flow path and the surface of the heat medium formed inside the rotary drum that drives and supports the casting drum or the casting band is preferably 5 to 50 mm, and preferably 10 to 40 mm. Is more preferable. If the thickness is less than 5 mm, sufficient surface smoothness cannot be obtained. If the thickness exceeds 50 mm, heat transfer is significantly reduced and it is difficult to make the temperature in the width direction uniform.
[0045]
The thickness of the casting band is preferably 0.5 to 2.0 mm, and more preferably 1.0 to 1.6 mm. When the thickness of the casting band is less than 0.5 mm, when the band is tensioned, there is a possibility that creased irregularities are generated on the band surface and the flatness of the band surface is impaired. On the other hand, if the thickness exceeds 2.0 mm, driving is performed while maintaining flatness, so that a very high tension is required, which may reduce the durability of the band.
[0046]
The contact time (contact distance) between the casting band and the rotating drum is preferably 6% or more, more preferably 8% or more of the non-contact time (non-contact distance). If the contact time is less than 6% of the non-contact time, it is difficult to make the distribution in the width direction of the casting band temperature uniform.
[0047]
The casting film-forming method of the present invention makes the distribution in the width direction of the casting support temperature uniform. As the casting support, there are a casting drum, a casting band, and the like. In order to make the distribution of the support temperature in the width direction uniform in the casting drum, a heat medium is circulated inside the casting drum. In order to make the support temperature distribution in the width direction uniform in the casting band, it is possible to circulate the heat medium inside the rotating drum that drives the casting band. Further, in the casting band, the heat medium can be circulated inside the guide roll disposed between the rotating drums.
[0048]
The film formed by the solution casting method according to the present invention can be used as a polarizing plate protective film. A polarizing plate can be formed by pasting this polarizing plate protective film on both surfaces of a polarizing film made of polyvinyl alcohol or the like. Furthermore, it can also be used as an optical functional film such as an optical compensation film having an optical compensation sheet affixed on the film or an antireflection film having an antiglare layer laminated on the film. From these products, it is also possible to constitute a part of a liquid crystal display device.
[0049]
Moreover, the solution film-forming method of the present invention can be applied to a solution film-forming method by adjusting two or more types of dopes and applying simultaneous multilayer coating. For example, when a film is formed by simultaneous three-layer coating, a large amount of cellulose triacetate is contained in the inner layer dope, and a relatively small amount of cellulose triacetate is included in the outer layer dope formed on the front and back surfaces of the inner layer. Contain. A film formed by applying three layers of these dopes simultaneously by the co-casting method has good moldability. However, the co-casting method in the solution casting method of the present invention is not limited to this embodiment.
[0050]
Further, in the present invention, a sequential casting method as described in JP-A-52-50078 or 53-134869 can also be used. In the sequential casting method, two or more casting ports are arranged on the support, and the first casting port is cast so that the thickness is less than the total thickness. The dope corresponding to the thickness of the film is layered and cast, and the drying rate on the support is increased and the film is peeled off in a short time to improve productivity. There is no particular limitation as long as the number of casting ports is two or more.
[0051]
In order to stably achieve the improvement in productivity by this sequential casting method, bubbles are not entrained when casting on a dry dope cast on a support, and the dope surface is not cast after casting. It is extremely important to cast so as not to foam. In order to carry out casting stably without causing these problems, it is preferable to carry out multilayer casting when the temperature of the film cast and dried on the support is 0 to 40 ° C. More preferably, the casting is carried out when the temperature is 10 to 30 ° C. Further, in order to substantially increase the productivity by sequential multi-layer casting as compared with single-layer casting, the amount of residual solvent in the film cast and dried on the support is in the range of 10 to 150% by weight. Sometimes it is desirable to cast multiple layers. More preferably, the layer casting is carried out when it is in the range of 30 to 120% by weight.
[0052]
If the temperature of the dope previously cast is 40 ° C. or more, the casting ribbon becomes unstable during the subsequent casting of the multilayer, and bubbles may be entrained or the layer cast may be foamed. Further, when the amount of the residual solvent of the dope cast in advance is 10% or less or 150% by weight or more, the improvement in productivity is hardly recognized with respect to the single layer casting.
[0053]
(Cellulose acylate)
The cellulose acylate, which is a basic material used in the solution casting film formation of the present invention, will be described in detail. The cellulose acylate of the present invention is not particularly limited as long as the effects of the present invention are exhibited. In the present invention, two or more different cellulose acylates may be mixed and used. However, among them, preferable cellulose acylates include the following materials. That is, the cellulose acylate satisfies all of the following formulas (I) to (III) with respect to the degree of substitution of cellulose with a hydroxyl group.
(I) 2.6 ≦ SA + SB ≦ 3.0
(II) 2.0 ≦ SA ≦ 3.0
(III) 0 ≦ SB ≦ 0.8
In the formula, SA and SB represent a substituent of an acyl group substituted with a hydroxyl group of cellulose, SA is a substitution degree of an acetyl group, and SB is a substitution degree of an acyl group having 3 to 22 carbon atoms.
[0054]
Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by esterifying some or all of these hydroxyl groups with acyl groups. The degree of acyl substitution means the proportion of cellulose esterified at each of the 2-position, 3-position and 6-position (100% esterification has a degree of substitution of 1). In the present invention, the total sum of the substitution degree of the hydroxyl group SA and SB is more preferably 2.7 to 2.96, and particularly preferably 2.80 to 2.95. The degree of substitution of SB is preferably 0 to 0.8, particularly preferably 0 to 0.6. Further, 28% or more of SB is a substituent at the 6-position hydroxyl group, more preferably 30% or more is a substituent at the 6-position hydroxyl group, more preferably 31%, particularly preferably 32% or more is the 6-position hydroxyl group. It is a substituent of a hydroxyl group. Furthermore, the cellulose acylate film in which the sum of the substitution degrees of SA and SB at the 6-position of cellulose acylate is 0.8 or more, more preferably 0.85, and particularly preferably 0.90 can be mentioned. it can. These cellulose acylate films can produce a solution having a preferable solubility, and in particular, a non-chlorine organic solvent can produce a good solution.
[0055]
The acyl group (SB) having 3 to 22 carbon atoms of the cellulose acylate used in the present invention may be an aliphatic group or an aryl group, and is not particularly limited. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. These preferred SBs include propionyl, butanoyl, keptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, iso-butanoyl, t-butanoyl, cyclohexanecarbonyl, oleoyl, benzoyl , Naphthylcarbonyl, cinnamoyl group and the like. Among these, preferred SB is propionyl, butanoyl, dodecanoyl, octadecanoyl, t-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like.
[0056]
The basic principle of the cellulose acylate synthesis method is described in Mita et al., Wood Chemistry pages 180-190 (Kyoritsu Shuppan, 1968). A typical synthesis method is a liquid phase acetylation method using a carboxylic acid anhydride-acetic acid-sulfuric acid catalyst. Specifically, cellulose raw materials such as cotton linter and wood pulp are pretreated with an appropriate amount of acetic acid, and then put into a pre-cooled carboxylic acid mixture to be esterified to complete cellulose acylate (2nd, 3rd and 6th). The total degree of acyl substitution at the position is approximately 3.00). The carboxylated mixed solution generally contains acetic acid as a solvent, carboxylic anhydride as an esterifying agent, and sulfuric acid as a catalyst. The carboxylic anhydride is usually used in a stoichiometric excess over the sum of the cellulose that reacts with it and the water present in the system. In order to hydrolyze excess carboxylic anhydride remaining in the system after completion of the acylation reaction and to partially neutralize the esterification catalyst, neutralizing agents (for example, calcium, magnesium, iron, An aqueous solution of aluminum or zinc carbonate, acetate or oxide) is added. Next, the obtained complete cellulose acylate is saponified and aged by maintaining it at 50 to 90 ° C. in the presence of a small amount of an acetylation reaction catalyst (generally, remaining sulfuric acid) to obtain the desired degree of acyl substitution and polymerization. The cellulose acylate having a degree is changed. When the desired cellulose acylate is obtained, the catalyst remaining in the system is completely neutralized with a neutralizing agent as described above, or in water or dilute sulfuric acid without neutralization. The cellulose acylate solution is added (or water or dilute sulfuric acid is added into the cellulose acylate solution) to separate the cellulose acylate, and the cellulose acylate is obtained by washing and stabilizing treatment.
[0057]
The degree of polymerization of the cellulose acylate preferably used in the present invention is a viscosity average degree of polymerization of 200 to 700, preferably 230 to 550, more preferably 230 to 350, and particularly preferably a viscosity average degree of polymerization of 240 to 320. The average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pages 105-120, 1962). Further details are described in JP-A-9-95538.
[0058]
When the low molecular component is removed, the average molecular weight (average polymerization degree) is increased, but the viscosity is lower than that of ordinary cellulose acylate, which is useful. Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent. In addition, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 weight of celluloses. When the amount of the sulfuric acid catalyst is within the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized. When the cellulose acylate of the present invention is used during film production, its water content is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.7% by mass or less. It is a cellulose acylate having a water content. In general, cellulose acylate contains water and is known to be 2.5 to 5% by mass. In order to obtain the moisture content of the cellulose acylate in the present invention, it is necessary to dry, and the method is not particularly limited as long as the desired moisture content can be achieved.
These cellulose acylates of the present invention are described in detail on pages 7 to 12 of the raw material cotton and the synthesis method in the Technical Report of the Japan Society of Invention (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention). It is described in.
[0059]
(Organic solvent that dissolves cellulose acylate)
Next, the organic solvent that dissolves the cellulose acylate of the present invention will be described. First, a non-chlorine organic solvent (an organic solvent not containing chlorine) that is preferably used in preparing the cellulose acylate solution of the present invention will be described. In the present invention, the non-chlorine organic solvent is not particularly limited as long as the object can be achieved as long as the cellulose acylate can be dissolved and cast and formed into a film. The non-chlorine organic solvent used in the present invention is preferably a solvent selected from esters, ketones or ethers having 3 to 12 carbon atoms. The ester, ketone and ether may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —COO—, —CO— and —O—) can also be used as a main solvent. It may have a functional group of In the case of the main solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group. Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone and methylcyclohexanone. Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.
[0060]
(Non-chlorine organic solvent)
The non-chlorine organic solvent used in the above cellulose acylate is selected from the various viewpoints described above, and is preferably as follows. That is, a preferred solvent for the cellulose acylate of the present invention is a mixed solvent of three or more different types (first solvent, second solvent, and third solvent), wherein the first solvent is methyl acetate, At least one selected from ethyl acetate, methyl formate, ethyl formate, acetone, dioxolane, dioxane, or a mixture thereof, and the second solvent is selected from ketones having 4 to 7 carbon atoms or acetoacetate, The third solvent is selected from alcohols having 1 to 10 carbon atoms or hydrocarbons, and more preferably alcohols having 1 to 8 carbon atoms. Note that when the first solvent is a mixed liquid of two or more kinds of solvents, the second solvent may be omitted. The first solvent is more preferably methyl acetate, acetone, methyl formate, ethyl formate, or a mixture thereof, and the second solvent is preferably methyl ethyl ketone, cyclopentanone, cyclohexanone, or methyl acetyl acetate. It may be.
[0061]
The alcohol as the third solvent is preferably linear, branched or cyclic, and is preferably a saturated aliphatic hydrocarbon. The hydroxyl group of the alcohol may be any of primary to tertiary. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. As the alcohol, fluorine-based alcohol is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like. Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene. These alcohols and hydrocarbons as the third solvent may be used alone or in combination of two or more, and are not particularly limited. As the third solvent, preferred specific compounds include alcohol, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and cyclohexanol, cyclohexane, hexane, Are methanol, ethanol, 1-propanol, 2-propanol, 1-butanol.
[0062]
The above three types of mixed solvents preferably contain a first solvent in a proportion of 20 to 95% by mass, a second solvent in a proportion of 2 to 60% by mass, and a third solvent in a proportion of 2 to 30% by mass, Furthermore, it is preferable that a 1st solvent is 30-90 mass%, a 2nd solvent is 3-50 mass%, and also 3-25 mass% of 3rd alcohol is contained. In particular, it is preferable that the first solvent is 30 to 90% by mass, the second solvent is 3 to 30% by mass, and the third solvent is alcohol and 3 to 15% by mass. In addition, when the first solvent is a mixed solution and the second solvent is not used, the first solvent is preferably contained in a ratio of 20 to 90% by mass and the third solvent in a ratio of 5 to 30% by mass, Furthermore, it is preferable that a 1st solvent is 30-86 mass%, and also a 3rd solvent is contained 7-25 mass%. The non-chlorine organic solvent used in the present invention is described in more detail in pages 12 to 16 in the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is described in detail. Preferred combinations of non-chlorine organic solvents of the present invention can include the following, but are not limited thereto.
[0063]
-Methyl acetate / acetone / methanol / ethanol / butanol (75/10/5/5/5, parts by mass),
-Methyl acetate / acetone / methanol / ethanol / propanol (75/10/5/5/5, parts by mass),
Methyl acetate / acetone / methanol / butanol / cyclohexane (75/10/5/5/5, parts by mass),
Methyl acetate / methyl ethyl ketone / methanol / butanol (80/10/5/5, parts by mass),
-Methyl acetate / acetone / methyl ethyl ketone / ethanol / isopropanol (75/10/10/5/7, parts by mass)
Methyl acetate / cyclopentanone / methanol / isopropanol (80/10/5/8, parts by mass),
・ Methyl acetate / acetone / butanol (85/5/5, part by mass),
Methyl acetate / cyclopentanone / acetone / methanol / butanol (60/15/15/5/6, parts by mass),
-Methyl acetate / cyclohexanone / methanol / hexane (70/20/5/5, parts by mass)
Methyl acetate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, parts by mass),
Methyl acetate / 1, 3 dioxolane / methanol / ethanol (70/20/5/5, parts by mass),
Methyl acetate / dioxane / acetone / methanol / ethanol (60/20/10/5/5, parts by mass),
Methyl acetate / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5, parts by mass),
[0064]
Methyl formate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, parts by mass),
-Methyl formate / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5, parts by mass)
Acetone / methyl acetoacetate / methanol / ethanol (65/20/10/5, parts by mass)
Acetone / cyclopentanone / ethanol / butanol (65/20/10/5, parts by mass)
Acetone / 1,3 dioxolane / ethanol / butanol (65/20/10/5, part by mass),
1,3 dioxolane / cyclohexanone / methyl ethyl ketone / methanol / butanol (55/20/10/5/5/5, parts by mass)
Etc.
In addition to the non-chlorine organic solvent of the present invention, the dope used in the present invention may contain dichloromethane in an amount of 10% by mass or less of the total organic solvent amount of the present technology.
[0065]
(Chlorine organic solvent)
In preparing the cellulose acylate solution of the present invention, a chlorinated organic solvent may be used as a main solvent in some cases. Details are described below. In the present invention, the chlorinated organic solvent is not particularly limited as long as the cellulose acylate can be dissolved, cast, and formed into a film. These chlorinated organic solvents are preferably dichloromethane and chloroform. Particularly preferred is dichloromethane. In addition, there is no particular problem in mixing an organic solvent other than the chlorinated organic solvent. In that case, it is preferable to use at least 50% by mass of dichloromethane. The non-chlorine organic solvent used in the present invention is described below. That is, as a preferable non-chlorine organic solvent, a solvent selected from esters, ketones, ethers, alcohols, hydrocarbons and the like having 3 to 12 carbon atoms is preferable. Esters, ketones, ethers and alcohols may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —COO—, —CO— and —O—) can also be used as a solvent. You may have group simultaneously. In the case of a solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group. Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone and methylcyclohexanone. Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.
[0066]
The alcohol used in combination with the chlorinated organic solvent may be linear, branched or cyclic, and among them, saturated aliphatic hydrocarbon is preferable. The hydroxyl group of the alcohol may be any of primary to tertiary. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. As the alcohol, fluorine-based alcohol is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like. Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene.
[0067]
The chlorine-free organic solvent used in combination with the chlorine-based organic solvent that is the main solvent used for dissolving the cellulose acylate is not particularly limited, but methyl acetate, ethyl acetate, methyl formate, ethyl formate, acetone, dioxolane , Dioxane, ketones having 4 to 7 carbon atoms or acetoacetate, alcohols having 1 to 10 carbon atoms or hydrocarbons. Preferred non-chlorine organic solvents used in combination are methyl acetate, acetone, methyl formate, ethyl formate, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl acetyl acetate, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol. , 2-butanol, and cyclohexanol, cyclohexane, and hexane. Although the following can be mentioned as a combination of the chlorinated organic solvent which is a preferable main solvent of this invention, It is not limited to these.
[0068]
Dichloromethane / methanol / ethanol / butanol (80/10/5/5, parts by mass),
Dichloromethane / acetone / methanol / propanol (80/10/5/5, parts by mass),
Dichloromethane / methanol / butanol / cyclohexane (80/10/5/5, parts by mass),
Dichloromethane / methyl ethyl ketone / methanol / butanol (80/10/5/5, parts by mass),
Dichloromethane / acetone / methyl ethyl ketone / ethanol / isopropanol (75/10/10/5/7, parts by mass),
Dichloromethane / cyclopentanone / methanol / isopropanol (80/10/5/8, parts by mass)
Dichloromethane / methyl acetate / butanol (80/10/10, parts by mass),
Dichloromethane / cyclohexanone / methanol / hexane (70/20/5/5, parts by mass)
Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, parts by mass),
Dichloromethane / 1, 3 dioxolane / methanol / ethanol (70/20/5/5, parts by mass),
Dichloromethane / dioxane / acetone / methanol / ethanol (60/20/10/5/5, parts by mass),
Dichloromethane / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5, parts by mass),
Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (70/10/10/5/5, parts by mass),
Dichloromethane / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5, parts by mass),
Dichloromethane / methyl acetoacetate / methanol / ethanol (65/20/10/5, parts by mass),
Dichloromethane / cyclopentanone / ethanol / butanol (65/20/10/5, parts by mass),
And so on.
[0069]
The cellulose acylate of the present invention is characterized in that it is a solution dissolved in an organic solvent in an amount of 10 to 30% by mass, more preferably 13 to 27% by mass, particularly 15 to 25% by mass. The cellulose acylate solution is preferred. The method for carrying out the cellulose acylate at these concentrations may be carried out so as to obtain a predetermined concentration at the stage of dissolution, or it is prepared as a low-concentration solution (for example, 9 to 14% by mass) and then concentrated as described later. You may adjust to a predetermined high concentration solution by a process. In addition, a cellulose acylate solution having a high concentration may be added to the cellulose acylate solution at a predetermined low concentration by adding various additives, and the cellulose acylate solution concentration of the present invention may be obtained by any method. There is no particular problem if it is implemented.
[0070]
(Characteristics of cellulose acylate solution)
Next, in this invention, it is preferable that the aggregate molecular weight of the cellulose acylate of the diluted solution which made the cellulose acylate solution 0.1-5 mass% with the organic solvent of the same composition is 10,000-15 million. More preferably, the associated molecular weight is 1 million to 10 million. This associated molecular weight can be determined by a static light scattering method. It is preferable to melt | dissolve so that the inertial square radius calculated | required simultaneously in that case may be 40-200 nm. A more preferable inertial square radius is 70 to 200 nm. Furthermore, the second virial coefficient is −2 × 10.^-4~ 4x10^-4The second virial coefficient is preferably −2 × 10.^-4~ 2x10^-4It is. Here, the definition of the associated molecular weight, the inertial square radius and the second virial coefficient in the present invention will be described. These were measured using the static light scattering method according to the following method. Although the measurement was performed in a dilute region for the convenience of the apparatus, these measured values reflect the behavior of the dope in the high concentration region of the present invention. First, cellulose acylate was dissolved in a solvent used for the dope to prepare 0.1 mass%, 0.2 mass%, 0.3 mass%, and 0.4 mass% solutions. In order to prevent moisture absorption, the cellulose acylate was dried at 120 ° C. for 2 hours and measured at 25 ° C. and 10% RH. The dissolution method was carried out according to the method employed at the time of dope dissolution (room temperature dissolution method, cooling dissolution method, high temperature dissolution method). Subsequently, these solutions and the solvent were filtered through a 0.2 μm Teflon (registered trademark) filter. The filtered solution was measured for static light scattering at intervals of 10 degrees from 30 degrees to 140 degrees at 25 ° C. using a light scattering measuring device (DLS-700 manufactured by Otsuka Electronics Co., Ltd.). The obtained data was analyzed by the BERRY plot method. In addition, the refractive index required for this analysis uses the value of the solvent calculated | required with the Abbe refractive system, and the refractive index concentration gradient (dn / dc) uses the differential refractometer (Otsuka Electronics Co., Ltd. product DRM-1021). The measurement was performed using the solvent and the solution used for the light scattering measurement.
[0071]
The cellulose acylate solution of the present invention preferably has a viscosity and dynamic storage modulus within the range. 1 mL of the sample solution was measured on a rheometer (CLS 500) using a Steel Cone having a diameter of 4 cm / 2 ° (both manufactured by TA Instruments). Measurement conditions were measured using Oscillation Step / Temperature Ramp with the range of 40 ° C to -10 ° C varied at 2 ° C / min, and static non-Newtonian viscosity at 40 ° C n * (Pa · sec) and storage at -5 ° C The elastic modulus G ′ (Pa) was determined. The measurement was started after the sample solution was kept warm at the measurement start temperature until the liquid temperature became constant. In the present invention, the viscosity at 40 ° C. is 1 to 300 Pa · sec, and the dynamic storage elastic modulus at −5 ° C. is 10,000 to 1,000,000 Pa. More preferably, the viscosity at 40 ° C. is 1 to 2000 Pa · sec, and the dynamic storage elastic modulus at −5 ° C. is 30,000 to 500,000 Pa, and particularly preferably, the viscosity at 40 ° C. is 10 to 10 150 Pa · sec and dynamic storage elastic modulus at −5 ° C. is 50,000 to 500,000 Pa.
[0072]
(Preparation of cellulose acylate solution (dope))
Next, regarding the preparation of the cellulose acylate solution (dope) of the present invention, the dissolution method is not particularly limited, and may be a room temperature dissolution method, a cooling dissolution method or a high temperature dissolution method, or a combination thereof. . Regarding these, for example, JP-A-5-163301, JP-A-61-106628, JP-A-58-127737, JP-A-9-95544, JP-A-10-95854, JP-A-10-45950, JP-A-2000-53784, Kaihei 11-322946, JP-A-11-322947, JP-A-2-276830, JP-A-2000-273239, JP-A-11-71463, JP-A-04-259511, JP-A-2000-273184, JP-A-11-323017, JP-A-11-323017 11-302388 describes a method for preparing a cellulose acylate solution. The above-described method for dissolving cellulose acylate in an organic solvent is applicable to the present invention as long as it is within the scope of the present invention. Details of these are described in detail on pages 22 to 25 of the non-chlorine-based solvent system in the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society for Invention). Be implemented in a way that Furthermore, the cellulose acylate dope solution of the present invention is usually subjected to solution concentration and filtration. Similarly, the dope solution of the invention is published in the technical report of the Invention Association (public technical number 2001-1745, published on March 15, 2001, Invention Association). It is described in detail on the page. In addition, when it melt | dissolves at high temperature, it is the case where it is more than the boiling point of the organic solvent to be used, and in that case, it uses in a pressurized state.
[0073]
(Polymerizable monomer)
The polymerizable monomer or polymerizable compound added to the cellulose acylate solution of the present invention may be any one that dissolves and disperses in the cellulose acylate solution. It is more preferably a polyfunctional monomer having a functional group that exhibits retardation adjusting ability, plasticity, slipperiness, and the like.
As the polymerizable monomer, an ethylenically unsaturated monomer and / or a compound having a 3-membered or 4-membered cyclic ether group can be used. Here, examples of the compound having a 3-membered cyclic ether group include compounds having an epoxy group, and examples of the compound having a 4-membered cyclic ether group include compounds having an oxetanyl group.
[0074]
(Ethylenically unsaturated monomer)
Specifically, ethylenically unsaturated monomers and / or ethylenically unsaturated monomers having a functional group are preferable examples. For example, vinyl acetates such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, and valeric acid Vinyl, vinyl pivalate, vinyl caproate, vinyl enanthate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl sorbate, vinyl benzoate Acrylic acid esters or methacrylic acid esters (hereinafter, acrylic acid esters or methacrylic acid esters may be abbreviated as (meth) acrylic acid esters). Acrylate, Eth Acrylate, n-butyl (meth) acrylate, heptyl (meth) acrylate, 2-methylbutyl (meth) acrylate, 3-methylbutyl (meth) acrylate, hexyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 2-methoxy Ethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl ( (Meth) acrylate, isononyl (meth) acrylate, isomyristyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, ε-caprolactone (me T) acrylate, benzyl (meth) acrylate, phenethyl (meth) acrylate, 4-cyanobutyl (meth) acrylate, 2-cyanoethyl (meth) acrylate, etc., as vinyl ethers, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, 2 -Ethylhexyl vinyl ether, hexyl vinyl ether, etc. As styrenes, styrene, 4-[(2-butoxyethoxy) methyl] styrene, 4-butoxymethoxystyrene, 4-butylstyrene, 4-decylstyrene, 4- (2-ethoxymethyl) ) Styrene, 4- (1-ethylhexyloxymethyl) styrene, 4-hydroxymethylstyrene, 4-hexylstyrene, 4-nonylstyrene, 4-octyloxymethylstyrene 2-octyl styrene, 4-octyl styrene, 4-propoxymethyl styrene, maleic acids such as dimethylmaleic acid, diethylmaleic acid, dipropylmaleic acid, dibutylmaleic acid, dicyclohexylmaleic acid, di-2-ethylhexylmaleic acid, di Nonylmaleic acid, dibenzylmaleic acid and the like can be mentioned, but are not limited thereto.
[0075]
More preferred ethylenically unsaturated monomers are vinyl esters, specifically vinyl acetate, vinyl propionate, vinyl butyrate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl valerate, vinyl pivalate, capron. Vinyl acid, vinyl enanthate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl sorbate, and other methyl acrylates, ethyl Acrylate, propyl acrylate, dimethylmaleic acid, diethylmaleic acid, propylmaleic acid and butylmaleic acid are also preferred monomers.
[0076]
The ethylenically unsaturated monomer having a functional group useful in the present invention is preferably one having an ultraviolet absorbing group or an antistatic group in the side chain of the polymer. Any copolymer can be used without limitation as long as it has a Tg of 50 ° C. or lower. As the ethylenic group of the ethylenically unsaturated monomer having a functional group, a vinyl group, an acryloyl group or a methacryloyl group is preferably used.
[0077]
Examples of the ultraviolet absorbing group of the ethylenically unsaturated monomer having an ultraviolet absorbing group useful in the present invention include a benzotriazole group, a salicylic acid ester group, a benzophenone group, an oxybenzophenone group, and a cyanoacrylate group. Any of them can be preferably used in the invention. In particular, a monomer having a benzotriazole group with little photoreactivity and almost no coloring is preferred.
[0078]
In the present invention, a commercially available ethylenically unsaturated monomer having an ultraviolet absorbing group may be used, or may be obtained by synthesis. As a commercially available product, for example, 1-hydroxy-2- (2-benzotriazole) -4- (2-methacryloyloxyethyl) benzene is commercially available as a reactive ultraviolet absorber RUVA-93 manufactured by Otsuka Chemical Co., Ltd. Yes. Similarly, 1-hydroxy-2- (2-benzotriazole) -4- (2-acryloyloxyethyl) benzene can be preferably used in the present invention. In addition, you may use the commercial item of the ethylenically unsaturated monomer which has the ultraviolet absorptive group of Unexamined-Japanese-Patent No. 2002-20410.
[0079]
Examples of the antistatic group of the ethylenically unsaturated monomer having an antistatic group useful in the present invention include a quaternary ammonium group, a sulfonate group, and a polyethylene oxide group. A quaternary ammonium group is preferable from the viewpoint of performance.
[0080]
The copolymerization ratio of the ethylenically unsaturated monomer having an antistatic group to the polymer obtained by photopolymerization in the present invention is 40 mass from the viewpoint of water absorption, durability, plasticity, necessary antistatic properties, etc. of the cellulose acylate film. % Or less, preferably 5 to 30% by mass.
[0081]
Although the typical example of the ethylenically unsaturated monomer which has a functional group which can be used in this invention is illustrated below, it is not limited to these. The UVM series shows examples of monomers having ultraviolet absorbing residues, and the ASM series shows examples of monomers having antistatic residues.
[0082]
[Chemical 1]

[0083]
[Chemical 2]

[0084]
[Chemical 3]

[0085]
[Formula 4]

[0086]
[Chemical formula 5]

[0087]
[Chemical 6]

[0088]
[Chemical 7]

[0089]
(Photo radical polymerization initiator)
The photopolymerization initiator useful in the present invention can be used without limitation as long as the ethylenically unsaturated monomer is an initiator that can be photopolymerized in the web, but known photopolymerization initiators can be used. . Photosensitizers can also be used. Specifically, benzoin methyl ether, benzoin-n-propyl ether, benzoin-n-butyl ether, benzoin silyl ether, methyl benzoin formate, benzyl, benzophenone, hydroxybenzophenone, p-methylbenzophenone, α-hydroxyisobutylphenone, p -Isopropyl-α-hydroxyisobutylphenone, acetophenone, Michler's ketone, α, α'-dichloro-4-phenoxyacetophenone, 1-hydroxy-1-cyclohexylacetophenone, 2,2-dimethoxy-2-phenylacetophenone, diacetyl, eosin, thionine 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropene, dichlorothioxanthone, diisopropylthioxanthone, pheny Disulfide-2-nitrosofluorene, butyroin, anisoin ethyl ether, di-t-butyl peroxide, benzoylthiazolyl sulfide, α-amyloxime ester, azobisisobutyronitrile, tetramethylthiuram disulfide, etc. it can. In this invention, when mixing a photoinitiator with an ethylenically unsaturated monomer in a cellulose acylate dope composition, 5-30 mass% of ethylenically unsaturated monomers with respect to a cellulose acylate, and a photoinitiator It is good to add about 1-30 mass% with respect to an ethylenically unsaturated monomer. In the present invention, after the photopolymerizable ethylenically unsaturated monomer is distributed in the cellulose acylate dope composition, the photopolymerization is caused in the web containing a lot of organic solvent or in the web even if the drying is considerably advanced. However, it is preferable to polymerize by irradiating with ultraviolet rays on a metal support.
[0090]
By incorporating a crosslinkable monomer having two ethylenically unsaturated groups into the cellulose acylate dope composition containing the ethylenically unsaturated monomer and the photopolymerization initiator of the present invention, the flexibility and toughness can be obtained after photopolymerization. A combined cellulose acylate film can be obtained. Examples of the crosslinkable monomer having two ethylenically unsaturated groups include polyester di (meth) acrylate and polyurethane di (meth) acrylate. A commercially available product is urethane acrylate (trade name, M-1310) manufactured by Toa Gosei Co., Ltd., which can be preferably used.
[0091]
These di (meth) acrylates of polyester or polyurethane have a number average molecular weight of 6,000 to 100,000, preferably 10,000 to 80,000.
[0092]
(3- or 4-membered cyclic ethers)
Another example of the polymerizable monomer or polymerizable compound added to the cellulose acylate solution of the present invention is a compound having an epoxy group. Here, examples of the compound having a 3-membered cyclic ether group include compounds having a 3-membered or 4-membered cyclic ether group, and examples of the compound having a 4-membered cyclic ether group include an oxetanyl group. The compound which has is mentioned. As the compound having a cyclic ether group, a compound having an epoxy group, particularly a compound having an alicyclic epoxy group is preferable from the viewpoint of high reactivity.
In the following description, in the description of the compound having a 3-membered or 4-membered cyclic ether group, a compound having an epoxy group will be described as an example. However, the present invention can be easily extended to a compound having an oxetanyl group. Is.
These compounds having an epoxy group can also be photopolymerized in the web, and plasticity can be imparted to the finished film. As a compound which has an epoxy group, what can be normally used for an adhesive agent etc. can be used.
[0093]
Examples of compounds having an epoxy group useful in the present invention include aromatic epoxy compounds (polyglycidyl ethers of polyhydric phenols), hydrogenated bisphenol A or glycidyl ethers of bisphenol A and epichlorohydrin, and epoxy novolac resins. (For example, cresol novolac polyglycidyl ether, phenol novolac polyglycidyl ether), resole epoxy resin, resorcinol diglycidyl ether and the like, and as the aliphatic epoxy resin, an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof is used. Typical examples include polyglycidyl ethers, polyglycidyl esters of aliphatic long-chain polybasic acids, and homopolymers and copolymers of glycidyl acrylate and glycidyl methacrylate. As ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, dipropylene glycol diglycidyl ether, tripropylene glycol glycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol di Glycidyl ether, nonapropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, glycerin triglycidyl ether, diglycerol triglycidyl ether, diglycerol tetraglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol triglycidyl ether, pentaerythritol tetra Of glycidyl ether and sorbitol Liglycidyl ether, cycloaliphatic epoxy compounds such as 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3', 4'-epoxy) cyclohexane-meta-dioxane, bis (3,4-epoxycyclohexylmethyl) adipate, vinylcyclohexenedioxide, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy- 6-methylcyclohexyl-3 ', 4'-epoxy-6-methylcyclohexanecarboxylate, methylenebis (3,4-epoxycyclohexane) dicyclopentadiene diepoxide, ethylene glycol di (3,4-epoxycyclohexylmethyl) Tellurium, ethylenebis (3,4-epoxycyclohexanecarboxylate), dicyclopentadiene diepoxide, diglycidyl ether of tris (2-hydroxyethyl) isocyanurate, triglycidyl ether of tris (2-hydroxyethyl) isocyanurate, poly Glycidyl acrylate, polyglycidyl methacrylate, glycidyl acrylate or copolymer of glycidyl methacrylate and other monomers, poly-2-glycidyloxyethyl acrylate, poly-2-glycidyloxyethyl methacrylate, 2-glycidyloxyethyl acrylate, 2-glycidyl Copolymers of oxyethyl acrylate or 2-glycidyloxyethyl methacrylate and other monomers, bis-2,2-hydroxycyclohexane Can be exemplified Le propane diglycidyl ether, it may be used in combination of two or more. In this invention, it is not limited to said exemplary compound, The compound analogized from these is also included.
[0094]
In the present invention, in addition to a compound having two or more 3-membered or 4-membered cyclic ether groups in the molecule, a compound having only one 3-membered or 4-membered cyclic ether group in the molecule is also desired. It can be blended and used according to performance.
[0095]
The compound having a UV-polymerizable 3- or 4-membered cyclic ether group in the present invention forms a polymer, a crosslinked structure, or a network structure not by radical polymerization but by cationic polymerization. Unlike radical polymerization, it is not affected by oxygen in the reaction system, so there is no induction period and the polymerization can be performed quickly.
[0096]
Although the representative example of the compound which has a 3 or 4 membered cyclic ether group which can be used in this invention below is illustrated, it is not limited to these.
[0097]
[Chemical 8]

[0098]
[Chemical 9]

[0099]
(Photocationic polymerization initiator)
A compound having a 3- or 4-membered cyclic ether group useful in the present invention undergoes a cationic polymerization reaction with a compound that forms a substance that initiates cationic polymerization upon irradiation with ultraviolet light as a catalyst. A group of double salts of onium salts that release a Lewis acid is particularly preferred as the one that initiates cationic polymerization upon UV irradiation.
[0100]
A typical example of such a compound is a compound represented by the following general formula (I).
Formula (I)
[(R¹)_a(R²)_b(R³)_c(R⁴)_dZ]^{+ W}[MeXv + w]^-W
Wherein the cation is onium, Z is S, Se, Te, P, As, Sb, Bi, O, halogen (eg, I, Br, Cl), or N = N (diazo), R¹ _a, R² _b, R³ _c, R⁴ _dAre organic groups which may be the same or different. a, b, c, and d are each an integer of 0 to 3, and a + b + c + d is equal to the valence of Z. Me is a metal or metalloid which is a central atom of a halide complex, and B, P, As, Sb, Fe, Sn, Bi, Al, Ca, In, Ti, Zn, Sc, V, Cr, Mn, Co, etc. X is halogen, w is the net charge of the halogenated complex ion, and v is the number of halogen atoms in the halogenated complex ion.
[0101]
Anion of general formula (I) [MeXv + w]^-WSpecific examples of tetrafluoroborate (BF)₄ ⁻), Hexafluorophosphate (PF)₆ ⁻), Hexafluoroantimonate (SbF)₆ ⁻), Hexafluoroarsenate (AsF)₆ ⁻), Hexachloroantimonate (SbCl₆ ⁻And the like.
[0102]
Furthermore, an anion of the general formula MXn (OH)-can also be used. Other anions include perchlorate ion (ClO).₄ ⁻), Trifluoromethyl sulfite ion (CF₃SO₃ ⁻), Fluorosulfonate ion (FSO)₃ ⁻), Toluenesulfonic acid ion, trinitrobenzene acid anion, and the like.
[0103]
Among these onium salts, it is particularly effective to use an aromatic onium salt as a cationic polymerization initiator. Among them, aromatic haloniums described in JP-A-50-151996, JP-A-50-158680 and the like are particularly effective. Salts, group VIA aromatic onium salts described in JP-A-50-151997, 52-30899, 59-55420, 55-125105, etc., JP-A-56-8428, 56- 149402, 57-192429, etc., oxosulfoxonium salts described in JP-B-49-17040, etc., aromatic diazonium salts described in US Pat. No. 4,139,655, etc. A thiopyrylium salt or the like is preferable. Moreover, an aluminum complex, a photodegradable silicon compound type | system | group polymerization initiator, etc. can be mentioned. The cationic polymerization initiator may be used in combination with a photosensitizer such as the benzophenone and derivatives thereof, the benzoin and derivatives thereof, and the thioxanthone and derivatives thereof. The sensitizer preferably has an absorption maximum from the near ultraviolet region to the visible light region.
[0104]
In the present invention, when a photopolymerization initiator and / or a photosensitizer is mixed with a compound having a 3- or 4-membered cyclic ether group in a cellulose acylate dope, the cellulose acylate has 3 or 4 members. The compound having a cyclic ether group of a member ring is 5 to 30% by weight, and the photopolymerization initiator is 1 to 30% by weight, preferably 1 to 10% by weight based on the compound having a cyclic ether group of 3 or 4 members. %.
[0105]
A compound having a 3- or 4-membered cyclic ether group and an ultraviolet absorber useful in the present invention may be mixed with a photopolymerization initiator to form a dope, or a compound having a 3- or 4-membered cyclic ether group It is good also as dope by mixing with.
[0106]
Examples of the ultraviolet absorbing group of the compound having a 3- or 4-membered cyclic ether group and an ultraviolet absorbing group useful in the present invention include a benzotriazole group, a salicylic acid ester group, a benzophenone group, an oxybenzophenone group, and a cyanoacrylate group. Any of these can be preferably used in the present invention. In particular, a benzotriazole group having low photoreactivity and almost no coloring is preferred.
[0107]
A cellulose acylate dope containing a compound having a 3-membered or 4-membered cyclic ether group and an ultraviolet absorbing group according to the present invention is formed in a solution casting film forming process, and ultraviolet rays are absorbed from a web irradiated with ultraviolet rays. Since the agent does not precipitate or volatilize, it is possible to obtain a polarizing plate protective film for a liquid crystal image display device with good productivity and excellent quality. Further, it is more preferable that the polymer of the compound having a 3-membered or 4-membered cyclic ether group and an ultraviolet absorbing group has water resistance to cellulose acylate as described above, and the Tg of the polymer is 50 ° C. or less. It is preferable that
[0108]
The proportion of the compound unit having an ultraviolet absorbing group constituting the photopolymerized polymer in the present invention is such that the compatibility of the polymer with the cellulose acylate, the mechanical property or the physical property of the cellulose acylate film is equivalent or more. Any material may be used as long as it has properties or sufficient ultraviolet absorption performance (may be in the range of 1 to 100% by mass).
[0109]
In the present invention, the cellulose acylate dope is mixed with a compound having a 3- or 4-membered cyclic ether group together with a photopolymerization initiator (in some cases, a photosensitizer). 5 to 30% by mass of a compound having a cyclic ether group having a member or 4 members, and 1 to 30% by weight, preferably 1 to the compound having a photopolymerization initiator having a cyclic ether group having 3 or 4 members. -10 mass%.
[0110]
An ethylenically unsaturated compound, a radical photopolymerization initiator, a compound having a 3-membered or 4-membered cyclic ether group, and a photocationic polymerization initiator can also be added to the cellulose acylate solution of the present invention.
[0111]
As other additives used in the cellulose acylate solution of the present invention, any additive that dissolves and disperses in the cellulose acylate coating solution may be used, such as an ultraviolet absorbing ability, an antistatic ability, a deterioration preventing ability, a peeling promoting ability, Those exhibiting retardation adjusting ability, plasticity, slipperiness and the like can be added within a range in which problems such as crying do not occur. Conventionally used plasticizers and ultraviolet absorbers can also be added.
[0112]
(Plasticizer)
There is no limitation in particular as an additive which can be used by this invention. 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. Further, plasticizers described in JP-A-11-80381, JP-A-11-124445, and JP-A-11-248940 can also be added. These plasticizers are desirably mixed in the dope so as to contain 0.1 to 20% by weight with respect to cellulose acylate.
[0113]
(UV absorber)
In addition, an ultraviolet absorber can be added to the dope. In particular, it preferably contains one or more ultraviolet absorbers. 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. Furthermore, a benzotriazole type ultraviolet absorber described in JP-A-8-29619 or an ultraviolet absorber described in JP-A-8-239509 can be added. In addition, a known ultraviolet absorber may be added. These ultraviolet absorbers are desirably mixed in the dope so as to contain 0.001 to 5% by weight with respect to cellulose acylate. For example, a benzotriazole-based ultraviolet absorber described in JP-A-8-29619 or an ultraviolet absorber described in JP-A-8-239509 can be added.
[0114]
Preferable UV inhibitors include 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], triethylene glycol -Bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) ) Propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di tert-butyl-4-hydroxyphenyl) propionate, N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 1,3,5-trimethyl-2,4,6 -Tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tris- (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate and the like. In particular, 2,6-di-tert-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate] is most preferred. Further, for example, metal deactivators of hydrazine compounds such as N, N′-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di- A phosphorus processing stabilizer such as tert-butylphenyl) phosphite may be used in combination. The amount of these compounds added is preferably 1 ppm to 1.0% by weight and more preferably 10 to 1000 ppm with respect to cellulose triacetate.
[0115]
(Release agent)
In addition, a release agent for facilitating the release operation can be added to the dope. Release agents include, but are not limited to, high melting point waxes, higher fatty acids and salts and esters thereof, silicone oil, polyvinyl alcohol, low molecular weight polyethylene, vegetable protein derivatives, and the like. Since the addition amount of the release agent affects the gloss and smoothness of the film surface, it is preferably contained in an amount of 0.001 to 2% by weight based on cellulose triacetate.
[0116]
(Fluorosurfactant)
A fluorine-based surfactant can also be added to the dope. A fluorosurfactant is a surfactant having a fluorocarbon chain as a hydrophobic group, and is used as a coating agent in an organic solvent or an antistatic agent because it significantly reduces the surface tension. Fluorosurfactants include C₈F₁₇CH₂CH₂O- (CH₂CH₂O)₁₀-OSO₃Na, C₈F₁₇SO₂N (C₃H₇) (CH₂CH₂O)₁₆-H, C₈F₁₇SO₂N (C₃H₇) CH₂COOK, C₇F₁₅COONH₄, C₈F₁₇SO₂N (C₃H₇) (CH₂CH₂O)₄-(CH₂)₄-SO₃Na, C₈F₁₇SO₂N (C₃H₇)-(CH₂)₃-N⁺(CH₃)₃・ I⁻, C₈F₁₇SO₂N (C₃H₇) CH₂CH₂CH₂N⁺(CH₃)₂-CH₂COO⁻, C₈F₁₇CH₂CH₂O (CH₂CH₂O)₁₆-H, C₈F₁₇CH₂CH₂O (CH₂)₃-N⁺(CH₃)₃・ I⁻, H (CF₂)₈-CH₂CH₂OCOCH₂CH (SO₃) COOCH₂CH₂CH₂CH₂-(CF₂)₈-H, H (CF₂)₆CH₂CH₂O (CH₂CH₂O)₁₆-H, H (CF₂)₈CH₂CH₂O (CH₂)₃-N⁺(CH₃)₃・ I⁻, H (CF₂)₈CH₂CH₂OCOCH₂CH (SO₃) COOCH₂CH₂CH₂CH₂C₈F₁₇, C₉F₁₇-C₆H₄-SO₂N (C₃H₇) (CH₂CH₂O)₁₆-H, C₉F₁₇-C₆H₄-CSO₂N (C₃H₇)-(CH₂)₃-N⁺(CH₃)₃・ I⁻However, it is not necessarily limited to these. The addition amount of the fluorosurfactant is preferably 0.002 to 2% by weight based on cellulose triacetate.
[0117]
(Other additives)
In addition, various additives may be further added to the dope at any stage after the preparation of the solution before and after the adjustment. Heat stabilizers such as alkaline earth metal salts such as calcium and magnesium, antistatic agents, flame retardants, lubricants, oils and the like.
[0118]
(Matting agent etc.)
The cellulose acylate solution of the present invention preferably contains a fine particle matting agent. The presence of the fine particle matting agent in the cellulose acylate film as the protective film for polarizing plate after film formation makes it Gives slip and scuff resistance. The fine particle matting agent is used by mixing and dispersing in a cellulose acylate coating solution. Examples of the fine particle matting agent include inorganic substances such as silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. It is preferable to contain fine particles and crosslinked polymer fine particles. Of these, silicon dioxide is preferable because it can reduce the haze of the film. The average particle size of the secondary particles of the fine particles is in the range of 0.01 to 1.0 μm, and the content thereof is preferably 0.005 to 0.3% by mass with respect to the cellulose acylate. In many cases, fine particles such as silicon dioxide are surface-treated with an organic substance, particularly a compound having a methyl group, but such a substance is preferable in the present invention because the haze of the film can be reduced. Preferred organic substances for the surface treatment include halosilanes, alkoxysilanes (particularly methoxysilane), silazane, siloxane and the like. The larger the average particle size of the fine particles, the greater the mat effect, and on the contrary, the smaller the average particle size, the better the transparency. Therefore, the average particle size of the preferred primary particles is 5 to 50 nm, more preferably 7 to 14 nm. It is. In the cellulose acylate film, these fine particles are usually present as aggregates, and it is preferable that irregularities of 0.01 to 1.0 μm are generated on the surface of the cellulose acylate film. Examples of the silicon dioxide fine particles include Aerosil 200, 200V, 300, R972, R972V, R974, R202, R812, OX50, TT600, etc. manufactured by Aerosil Co., Ltd., preferably AEROSIL R972, R972V, R974, R202, R812. Two or more of these matting agents may be used in combination. When using 2 or more types together, it can mix and use in arbitrary ratios. In this case, matting agents having different average particle sizes and materials, for example, AEROSIL 200V and R972V can be used in a mass ratio of 0.1: 99.9 to 99.9 to 0.1.
[0119]
Furthermore, the cellulose acylate solution of the present invention preferably contains an antioxidant. As the antioxidant, a hindered phenol compound is preferably used, and 2,6-di-t-butyl- p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-) 4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio)- 6- (4-Hydroxy-3,5-di-t-butylanilino) -1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5 Di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 1,3,5-trimethyl-2,4,6- Examples thereof include tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene and tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate. In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] is preferred. Further, for example, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di-t A phosphorus-based processing stabilizer such as -butylphenyl) phosphite may be used in combination. The amount of these compounds added is preferably 1 ppm to 1.0%, more preferably 10 to 1000 ppm in terms of mass ratio with respect to cellulose acylate.
[0120]
(Peeling layer)
In the present invention, it is preferable to have a release layer between the recoverable cellulose acylate layer and the difficultly recoverable cellulose acylate layer.
The release layer is a cellulose acylate that can be reused when the cellulose acylate film scraps generated when slitting cellulose acylate films containing monomers and polymerizable compounds to produce semi-finished cellulose acylate films are reused. It is preferable that the monomer and the polymerized compound that are difficult to reuse can be separated, and the amount of waste can be reduced.
The release layer is formed of a polymer having a solubility different from that of the cellulose ester layer in a separation solvent (a solvent used when separating the cellulose ester layer and the monomer or polymerizable compound coating layer). This polymer is determined by the separation solvent, for example, cellulose acetate, cellulose propionate, cellulose acetate propionate, cellulose butyrate, cellulose acetate butyrate, polyamide, polycarbonate, polysulfone, polyethersulfone, polyarylate, There is polyphenylene oxide. A material having a low acylate substitution rate of cellulose acylate as described in JP-A-5-93976 is different from the cellulose acylate of the present invention in solubility in acetone / methanol (70/30), which is a preferable example. It is.
These may be used alone or blended as necessary. These polymers having a molecular weight of 10,000 or more can be used, but usually 20,000 to 800,000 are used.
A preferred example is a gelatin layer mainly composed of gelatin used in a silver halide photographic light-sensitive material and excluding materials such as silver halide and coupler.
[0121]
The thickness of the release layer is not particularly limited, but is preferably in the range of 0.2 to 10 μm. The release layer is formed by casting a release layer dope or applying a release layer coating solution. This release layer dope is mainly composed of the above-described polymer and organic solvent. The organic solvent varies depending on each polymer, but it is necessary to have an affinity that does not cause phase separation or clouding when contacting with the dope of an adjacent layer. For example, dichloromethane, chloroform, tetrachloroethylene, dimethylacetamide, acetone, methyl ethyl ketone, There are methanol and ethanol. The amount of the polymer in the dope for the release layer is preferably 3 to 50% by weight, particularly preferably 8 to 27% by weight.
[0122]
Separation of the release layer can be selected according to the material of the release layer, and the separation method is performed by dipping in a separation solvent. The cellulose ester layer thus separated can be treated by a normal purification process and used as a regenerated raw material. For the separation of the cellulose ester layer and the monomer polymerization layer, a known general separation method such as sedimentation separation using a specific gravity difference, centrifugation, or the like can be used.
[0123]
(Surface treatment of cellulose acylate laminate film)
In the present invention, an improvement in adhesion between the cellulose acylate film and each functional layer (for example, a release layer, an undercoat layer, and a back layer) can be achieved by performing a surface treatment. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs under a low pressure gas of 10-3 to 20 Torr, and plasma treatment under atmospheric pressure is also preferred. A plasma-excitable gas is a gas that is plasma-excited under the above conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail on pages 30 to 32 in the Japan Society of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Invention Association). Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 Kgy is used under 10 to 1000 Kev, and more preferably irradiation energy of 20 to 300 Kgy is used under 30 to 500 Kev. Among these, an alkali saponification treatment is particularly preferable, and it is extremely effective as a surface treatment of a cellulose acylate film.
[0124]
The alkali saponification treatment is also preferably performed by applying a saponification solution. Examples of the coating method include a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method. The solvent of the alkali saponification coating solution has good wettability because it is applied to the transparent support of the saponification solution, and the surface state remains good without forming irregularities on the surface of the transparent support by the saponification solution solvent. It is preferred to select a solvent to keep. Specifically, an alcohol solvent is preferable, and isopropyl alcohol is particularly preferable. An aqueous solution of a surfactant can also be used as a solvent. The alkali of the alkali saponification coating solution is preferably an alkali that dissolves in the above solvent, and more preferably KOH or NaOH. The pH of the saponification coating solution is preferably 10 or more, more preferably 12 or more. The reaction conditions during alkali saponification are preferably 1 second to 5 minutes at room temperature, more preferably 2 seconds to 1 minute, and particularly preferably 3 seconds to 30 seconds. After the alkali saponification reaction, it is preferable to wash the surface on which the saponification solution is applied with water or with an acid and then with water. Further, the coating-type saponification treatment and the alignment film uncoating described later can be performed continuously, and the number of steps can be reduced. Furthermore, the cellulose acylate film obtained in the present invention may be subjected to alkali treatment by a dipping method. That is, the surface treatment can be carried out by continuously or intermittently arranging an alkali treatment bath, a water washing bath, an acid treatment bath, a water washing bath, and optionally a rinse bath. In this case, each solution has the same composition as the corresponding solution used in the coating method.
[0125]
(Use of cellulose acylate laminated film)
The use of the cellulose acylate laminated film produced in the present invention will be briefly described first. The optical film of the present invention is particularly useful for a polarizing plate protective film. When using as a polarizing plate protective film, the manufacturing method of a polarizing plate is not specifically limited, It can manufacture by a general method. There is a method in which the obtained cellulose acylate film is treated with an alkali and bonded to both sides of a polarizer prepared by immersing and stretching a polyvinyl alcohol film in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. Instead of alkali treatment, easy adhesion processing as described in JP-A-6-94915 and JP-A-6-118232 may be performed. Examples of the adhesive used to bond the protective film treated surface and the polarizer include polyvinyl alcohol adhesives such as polyvinyl alcohol and polyvinyl butyral, vinyl latexes such as butyl acrylate, and the like. The polarizing plate is composed of a polarizer and a protective film that protects both surfaces of the polarizer, and further includes a protective film bonded to one surface of the polarizing plate and a separate film bonded to the other surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the liquid crystal plate. Moreover, a separate film is used in order to cover the adhesive layer bonded to a liquid crystal plate, and is used for the surface side which bonds a polarizing plate to a liquid crystal plate. In a liquid crystal display device, a substrate containing liquid crystal is usually disposed between two polarizing plates. However, a polarizing plate protective film to which the optical film of the present invention is applied can provide excellent display properties regardless of the location. . In particular, since the polarizing plate protective film on the outermost surface of the display side of the liquid crystal display device is provided with a transparent hard coat layer, an antiglare layer, an antireflection layer, and the like, the polarizing plate protective film is particularly preferably used in this portion.
[0126]
The cellulose acylate laminate film of the present invention (also simply referred to as “cellulose acylate film” in the present invention) can be used in various applications, and is particularly effective when used as an optical compensation sheet for liquid crystal display devices. The cellulose acylate film 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 Crystal), OCB (OpticallySyPB). 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. The cellulose acylate film 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. The cellulose acylate film of the present invention may be used as a support for an optical compensation sheet of an STN type liquid crystal display device having an STN mode liquid crystal cell. 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 ) 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. The cellulose acylate film of the present invention is particularly advantageously used as a support for an optical compensation sheet of a VA liquid crystal display device having a VA mode liquid crystal cell. The cellulose acylate film of the present invention is also advantageously 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.
[0127]
(Optical compensation sheet)
The cellulose acylate film of the present invention is also advantageously used as an optical compensation sheet for TN-type, STN-type, HAN-type, and GH (Guest-Host) type reflective liquid crystal display devices. These display modes have been well known since ancient times. The TN type reflection type liquid crystal display device is described in JP-A-10-123478, WO98848320, and Japanese Patent No. 3022477. The optical compensation sheet used for the reflection type liquid crystal display device is described in WO00-65384. The cellulose acylate film of the present invention is also advantageously used as a support for an optical compensation sheet of an ASM type liquid crystal display device having a liquid crystal cell in an ASM (Axially 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 Kume et al. (Kume et al., SID 98 Digest 1089 (1998)). The detailed uses of the cellulose acylate films described above are described in detail on pages 45 to 59 in the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society for Invention). Has been.
[0128]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these.
[0129]
<Preparation of cellulose triacetate solution>
With the formulation shown in Table 1, cellulose triacetate powder (average size 2 mm) was gradually added and charged into a stainless steel dissolution tank having stirring blades while thoroughly stirring the mixed solvent with the additive. After the addition, the tank was depressurized and dispersed for 1 hour, and stirred at 25 ° C. for 2 hours to swell the cellulose triacetate. Note that methyl acetate and ethanol, acetone, methanol, butanol, and dichloromethane, which are solvents, all have a water content of 0.2% by mass or less.
[0130]
[Table 1]

[0131]
<Preparation of cellulose triacetate dope solution (cooling dissolution)>
The cellulose triacetate solution described above was fed with a screw extruder and passed through the cooling part at −70 ° C. for 10 minutes. Cooling was performed using a refrigerant at −80 ° C. (3M, “Fluorinert”) cooled by a refrigerator. The solution obtained by cooling is heated to 120 ° C. by a heat exchanger provided with a static mixer, held for 3 minutes, cooled, transferred to a stainless steel container at 50 ° C., and heated at 50 ° C. The mixture was stirred for 2 hours for degassing. After that, it is filtered with a filter paper having absolute filtration accuracy of 0.01 mm (“Toyo Filter Paper Co., Ltd.,“ # 63 ”), and further filtered with filter paper having absolute filtration accuracy of 0.0025 mm (“ FH 025 ”, manufactured by Paul). Filtration was performed to prepare a cellulose triacetate dope solution.
[0132]
<Production and excision of cellulose triacetate film>
As shown in Table 2, the filtered dope was cast by a band casting machine having an endless stainless steel belt that moved infinitely so that the casting width was 1000 mm. The casting band made of stainless steel and having a thickness of 1.5 mm was used. The contact time between the casting band and the rotating drum was 12% of the non-contact time. Table 2 shows the temperature of the stainless steel belt support in the casting portion. Dry nitrogen at 15 ° C. was introduced into the ultraviolet irradiation booth installed in the band casting machine to control the oxygen concentration. Photopolymerization was performed by irradiating with the amount of ultraviolet rays shown in Table 2. The dope film exiting the booth was dried with 80 ° C. drying air for 3 minutes, the film web was peeled off with a residual solvent amount of 50%, dried at 90 to 115 ° C., and then dried at 110 to 130 ° C. with a roll dryer. The dried web was wound up with a residual solvent amount of 0.2% by mass to obtain a 60 μm cellulose acetate film. The obtained sample was subjected to knurling with a height of 100 μm in a portion of 2 to 10 mm from the end, and wound into a roll having a length of 500 m.
The variation in the distance between the tip of the casting die and the casting band was 150 μm or less. And in the experiment, the foaming phenomenon on the casting band and the peeled state of the film were observed, and the following evaluation was performed.
[0133]
<Production of polarizer>
The PVA film was immersed in an aqueous solution of 2.0 g / L of iodine and 4.0 g / L of potassium iodide at 25 ° C. for 240 seconds, and further immersed in an aqueous solution of boric acid 10 g / L at 25 ° C. for 60 seconds, followed by tenter stretching. The film was introduced into a machine, stretched 5.3 times, and thereafter, the width was kept constant and dried in an atmosphere at 80 ° C. while shrinking, and then separated from the tenter and wound up. The moisture content of the PVA film before starting stretching was 31%, and the moisture content after drying was 1.5%.
The difference in transport speed between the left and right tenter clips was less than 0.05%. Wrinkles and film deformation at the tenter exit were not observed.
The transmittance of the obtained polarizer at 550 nm was 43.7%, and the degree of polarization was 99.97%.
[0134]
<Preparation of polarizing plate>
The formed cellulose acetate film is immersed in a 1.5N NaOH aqueous solution at 55 ° C. for 1 minute to saponify both surfaces, washed thoroughly with dilute sulfuric acid and water, dried, and then dried with a polyvinyl alcohol adhesive on each cellulose triacetate side. It apply | coated to the thickness of 30 micrometers, it bonded together on both sides of the said polarizer, and also dried at 80 degreeC, and created the polarizing plate.
This polarizing plate was exposed for 500 hours in an atmosphere of 80 ° C. and 90% RH. In any of the present inventions, the degree of polarization was 99% or more, and sufficient durability was recognized.
[0135]
<Evaluation>
(Foaming phenomenon)
The foaming phenomenon during drying was observed on the casting band.
○: There was no foaming phenomenon on the casting band.
X: The foaming phenomenon was recognized on the casting band.
[0136]
(Peeling state)
The state after peeling off from the casting band was observed.
○: There was no unpeeled dope on the casting band.
Δ: Slight deposits were observed at the edge of the casting band, but no growth occurred.
X: The state where the peeling residue grew.
[0137]
(Haze)
The haze of the cellulose acetate film was examined using a 1001DP type manufactured by Nippon Denshoku Industries Co., Ltd., stored at 90 ° C./80% high temperature and high humidity for 500 hours before and after.
[0138]
(Surface roughness (Ra))
The calculation principle of the surface roughness (centerline average roughness) is in accordance with the centerline average roughness specified in JIS-B0601 “Surface roughness”. The test was performed using a SE-3F.
[0139]
(Polarization degree) The polarization degree of the polarizing plate was determined by calculating the parallel transmittance Yp and the direct transmittance Yc in the visible region with a spectrophotometer, and determining the polarization degree P based on the following equation.
P = ((Yp−Yc) / (Yp + Yc))^1/2
[0140]
<Result>
In addition to the aforementioned foaming phenomenon and peeled state, the haze and surface roughness of the film were measured. The results are shown in Table 2.
From Table 2, it was confirmed that the present invention did not cause a foaming phenomenon, the peeled state was good, and the surface roughness and haze were also good. In particular, it was found that the haze after aging at high temperature and high humidity did not deteriorate and no precipitation of low molecular weight was observed. On the other hand, it was confirmed that Comparative Examples 101 and 106 having a high oxygen concentration in the ultraviolet irradiation booth had a poor peeling state and deteriorated surface roughness and haze, and the doped film surface temperature was higher than the boiling point of −3 ° C. of the dope main solvent. Comparative Examples 103 and 105 cause a foaming phenomenon, the peeling state is poor, the surface roughness and haze are found to be deteriorated, and Comparative Examples 102 and 104 where the dope film surface temperature is not uniform in the width direction are somewhat bad in the peeling state. It can be understood that the surface roughness and haze performance are inferior to those of the present invention.
Further, it can be seen that Comparative Example 107 in which the irradiation dose distribution is not uniform and Comparative Example 108 in which the irradiation time is outside the claimed range of the present invention have a poor peeled state and no surface roughness and haze performance.
Furthermore, in Comparative Examples 109 and 110 not containing the polymerizable monomer of the present invention and the photopolymerization initiator, the haze at high temperature and high humidity deteriorated, and the result that the additive easily started to cry was reproduced.
[0141]
[Table 2]

[0142]
【The invention's effect】
According to the present invention, it is possible to obtain a cellulose acylate film and a polarizing plate that do not cry out additives that satisfy various required characteristics, have little increase in haze, have no deterioration in durability, and can effectively use materials. it can.
[0143]
[Brief description of the drawings]
FIG. 1 is a schematic view of an embodiment of a casting film production line for performing a casting film production method according to the present invention.
[Explanation of symbols]
11 Mixing tank
12 Liquid feed pump
13 Filter
14 Casting die
15 Casting band
16 Casting side rotating drum
17 Non-casting side rotating drum
18 Guide roll
19 Stripping roll
20 Guide roll
21 Winding roll
22 Drying section
23 Film

Claims (3)

Method for producing a film by casting a cellulose acylate dope solution containing an ethylenically unsaturated monomer and / or an ethylenically unsaturated monomer having a functional group and a photopolymerization initiator onto a casting support from a casting die The method for producing a cellulose acylate film according to claim 1, wherein the oxygen concentration in the ultraviolet irradiation booth when the dope solution on the casting support is irradiated with ultraviolet rays is 10% or less. A cellulose acylate film formed by the method for producing a cellulose acylate film according to claim 1. A polarizing plate using the cellulose acylate film according to claim 2.

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