JP4114233B2 - Method for preparing cellulose acylate solution, method for producing cellulose acylate film, and cellulose acylate film - Google Patents

Description

【００４６】
一般式（Ｉ）、（II）、（III）の式中、Ｒは、それぞれ炭素原子数が１以上４以下のアルキル基である。上記一般式（Ｉ）、（II）又は（III）で示される化合物の例としては、リン酸２，２′−メチレンビス（４，６−ジ−ｔｅｒｔ−ブチルフェニル）ナトリウム（アデカスタブＮＡ−１０、旭電化（株）製）及びビス（ｐ−エチルベンジリデン）ソルビトール（ＮＣ−４、三井東圧化学（株）製）が含まれる。
【００４７】
酸化防止剤としては、下記一般式（IV）で表されるものが用いられる。
【００４８】
【化２】

【００４９】
一般式（IV）のＲ₁はアルキル基を表し、Ｒ₂、Ｒ₃及びＸは、それぞれ水素原子、アルキル基、アルケニル基、アリール基、ヘテロ環基、アルコキシ基、アルケノキシ基、アリールオキシ基、アルキルチオ基、アルケニルチオ基、アリールチオ基、ヘテロ環オキシ基、ヒドロキシ基、アミノ基、カルバモイル基、スルファモイル基、アルコキシカルボニル基、アリールオキシカルボニル基、ハロゲン原子、ニトロ基、シアノ基、アシル基、アシルオキシ基を表す。ｍは０〜２の整数を表す。Ｒ₂、Ｒ₃及びＸは互いに同一でもよいし異なっていてもよい。上記アルキル基は、例えば、メチル、エチル、プロピル、ｉｓｏ−プロピル、ｔｅｒｔ−ブチル、シクロヘキシル、ｔｅｒｔ−ヘキシル、ｔｅｒｔ−オクチル、ドデシル、ヘキサデシル、オクタデシル、ベンジルなどの直鎖、分岐、又は環状のアルキル基を表し、上記アルケニル基は、例えば、ビニル、アリル、２−ペンテニル、シクロヘキセニル、ヘキセニル、ドデセニル、オクタデセニルなどの直鎖、分岐、又は環状のアルケニル基を表し、上記アリール基は、例えば、フェニル、ナフチル、アントラニルなどのベンゼン単環や縮合多環のアリール基を表し、上記ヘテロ環基は、例えば、フリル、ピロリル、イミダゾリル、ピリジル、プリニル、クロマニル、ピロリジル、モルホリニルなどの窒素原子、硫黄原子、酸素原子の少なくとも一つを含む５〜７員環からなる基を表す。中でもヒンダードフェノール系の化合物が好ましく、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燐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重量割合で１ｐｐｍ〜１．０％が好ましく、１０〜１０００ｐｐｍが更に好ましい。
【００５０】
ライトパイピング防止用の着色剤としては下記一般式（Ｖ）、（VI）に示す化合物が挙げられる。
【００５１】
【化３】

【００５２】
一般式（Ｖ）、（VI）の式中、Ｘは酸素原子、又は、ＮＲ₂₃を表す。Ｒ₁〜Ｒ₈、Ｒ₁₂〜Ｒ₂₃は、それぞれ水素原子、水酸基、脂肪族基、芳香族基、複素環基、ハロゲン原子、シアノ基、ニトロ基、ＣＯＲ₉、ＣＯＯＲ₉、ＮＲ₉Ｒ₁₀、ＮＲ₁₀ＣＯＲ₁₁、ＮＲ₁₀ＳＯ₂Ｒ₁₁、ＣＯＮＲ₉Ｒ₁₀、ＳＯ₂ＮＲ₉Ｒ₁₀、ＣＯＲ₁₁、ＳＯ₂Ｒ₁₁、ＯＣＯＲ₁₁、ＮＲ₉ＣＯＮＲ₁₀Ｒ₁₁、ＣＯＮＨＳＯ₂Ｒ₁₁、又はＳＯ₂ＮＨＣＯＲ₁₁を表し、Ｒ₉、Ｒ₁₀はそれぞれ水素原子、脂肪族基、芳香族基、複素環基を表し、Ｒ₁₁は脂肪族基、芳香族基、又は複素環基を表す。
【００５３】
Ｒ₁〜Ｒ₂₃で表される脂肪族基は、炭素数１〜２０のアルキル基（例えば、メチル、エチル、ｎ−ブチル、イソプロピル、２−エチルヘキシル、ｎ−デシル、ｎ−オクタデシル）、炭素数１〜２０のシクロアルキル基（例えば、シクロベンジル、シクロヘキシル）又はアリル基を表し、これらは更に置換基（例えば、ハロゲン原子、水酸基、シアノ基、ニトロ基、カルボン酸基、炭素数６〜１０のアリール基、炭素数０〜２０のアミノ基、炭素数１〜２０のアミド基、炭素数１〜２０のカルバモイル基、炭素数２〜２０のエステル基、炭素数１〜２０のアルコキシ基又はアリーロキシ基、炭素数１〜２０のスルホンアミド基、炭素数０〜２０のスルファモイル基、５又は６員の複素環を有していてもよい。Ｒ₁〜Ｒ₂₃で表される芳香族基は炭素数６〜１０のフェニル、ナフチルなどのアリール基を表し、前記に挙げた置換基及び炭素数１〜２０のメチル、エチル、ｎ−ブチル、ｔｅｒｔ−ブチル、オクチルなどのアルキル基からなる置換基を有していてもよい。Ｒ₁〜Ｒ₁₁で表される複素環基は、５又は６員の複素環を表し、前記の置換基を有していてもよい。以下化４〜化９に一般式（Ｖ）、（VI）で表される化合物の好ましい例（Ｖ−１）〜（Ｖ−２５）、及び（VI−１）〜（VI−４）を示す。
【００５４】
【化４】

【００５５】
【化５】

【００５６】
【化６】

【００５７】
【化７】

【００５８】
【化８】

【００５９】
【化９】

【００６０】
着色剤の含有量は、セルロースアシレートに対する重量割合で１０〜１０００ｐｐｍが好ましく、５０〜５００ｐｐｍが更に好ましい。この様に着色剤を含有させることにより、セルロースアシレートフィルムのライトパイピングが減少でき、黄色味を改良することができる。これらの化合物は、セルロースアシレート溶液の調製の際に、セルロースアシレートや溶媒と共に添加してもよいし、溶液調製中や調製後に添加してもよい。
【００６１】
また、本発明のセルロースアシレート溶液には、必要に応じて更に種々の添加剤を溶液の調製前から調製後のいずれの段階で添加してもよい。添加剤としては、紫外線吸収剤、カオリン、タルク、ケイソウ土、石英、炭酸カルシウム、硫酸バリウム、酸化チタン、アルミナなどの無機微粒子、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。
【００６２】
本発明のドープを用いたセルロースアシレートフィルムの製膜方法について述べる。
【００６３】
本発明のセルロースアシレートフィルムを製造する設備としては従来セルロースアシレートフィルムの製造に用いられている溶液流延製膜法のものが利用できる。その設備と製造方法の概略を述べると、前述の調製装置で調製されたドープは、例えば回転数によって高精度に定量送液できる加圧型定量ギヤポンプを通して加圧型ダイに送られる。精密ギヤポンプから加圧ダイに送り込まれたドープは加圧型ダイの口金（スリット）からエンドレスに回転している支持体の上に均一に流延され、支持体がほぼ一周したところで、生乾きのフィルム（ウェブ）として支持体から、回転しているロール群に通されながら乾燥され、乾燥されたフィルムは搬送後巻き取り機で所定の長さに巻き取られる。
【００６４】
本発明に有用な流延方法としては、調製されたドープを加圧ダイから支持体上に均一に押し出す方法、一旦支持体上に流延されたドープをブレードで膜厚を調節するドクターブレードによる方法、或いは逆回転するロールで調節するリバースロールコーターによる方法等の流延装置があるが、加圧ダイによる方法が好ましい。加圧ダイにはコートハンガータイプやＴダイタイプ等があるが何れも好ましく用いることができる。また、ここで挙げた方法以外にも従来知られているセルロースアシレート溶液からセルロースアシレートを流延製膜する種々の方法（例えば特開昭６１−９４７２４号、同６１−１４８０１３号、特開平４−８５０１１号、同４−２８６６１１号、同５−１８５４４３号、同５−１８５４４５号、同６−２７８１４９号、同８−２０７２１０号公報などに記載の方法）を好ましく用いることができ、用いる溶媒の沸点等の違いを考慮して各条件を設定することによりそれぞれの公報に記載の内容と同様の効果が得られる。
【００６５】
本発明のセルロースアシレートフィルムを製造するのに使用されるエンドレスに走行する支持体としては、表面がクロムメッキによって鏡面仕上げされたドラムや表面研磨によって鏡面仕上げされたステンレスベルト（バンドといってもよい）が用いられる。
【００６６】
本発明のセルロースアシレートフィルムの製造に用いられる加圧ダイの支持体上への配置は１基或いは２基以上の設置でもよい。好ましくは１基又は２基である。２基以上設置する場合には流延するドープ量をそれぞれのダイスに種々な割合にわけてもよく、複数の精密定量ギヤポンプからそれぞれの割合でダイにドープを送液する。
【００６７】
本発明のセルロースアシレートフィルムの製造に係わる支持体上におけるドープの乾燥は、一般的にはドラム或いはベルトの表面側、つまり支持体上にあるウェブの表面から熱風を当てる方法、ドラム或いはベルトの裏面から熱風を当てる方法、温度コントロールした液体をベルトやドラムのドープ流延面の反対側の裏面から接触させて、伝熱によりドラム或いはベルトを加熱し表面温度をコントロールする液体伝熱方法などがあるが、裏面液体伝熱方式が好ましい。
【００６８】
流延される前の支持体の表面温度はドープに用いられている溶媒の沸点以下であれば何度でもよい。しかし乾燥を促進するためには、また支持体上での流動性を失わせるためには、使用される溶媒の内の最も沸点の低い溶媒の沸点より１から１０℃低い温度に設定することが好ましい。
【００６９】
セルロースアシレートフィルムを製造する速度はベルトの長さ、乾燥方法、ドープ溶媒組成等によっても変化するが、ウェブをベルトから剥離する時点での残留溶媒の量によって殆ど決まってしまう。つまり、ドープ膜の厚み方向でのベルト表面付近での溶媒濃度が高すぎる場合には、剥離した時、ベルトにドープが残ってしまい、次の流延に支障を来すため、剥離残りは絶対あってはならないし、更に剥離する力に耐えるだけのウェブ強度が必要であるからである。剥離時点での残留溶媒量は、ベルトやドラム上での乾燥方法によっても異なり、ドープ表面から風を当てて乾燥する方法よりは、ベルト或いはドラム裏面から伝熱する方法のほうが効果的に残留溶媒量を低減することができるのである。
【００７０】
本発明のセルロースアシレートフィルムの製造に係わるウェブ（ここで、ウェブとは剥離されたドープ膜から乾燥されてフィルムに至るまでをウェブと呼ぶことにするが、それらの境界は定かではない）乾燥方法について述べる。支持体が１周する直前の剥離位置で剥離されたウェブは、千鳥状に配置されたロール群に交互に通して搬送する方法や剥離されたウェブの両端をクリップで把持させて非接触的に搬送する方法などにより搬送しつつ、搬送中のウェブ両面に所定の温度の風を当てる方法やマイクロウェーブなどの加熱手段などを用いる方法によって乾燥が行われる。急速な乾燥はウェブの平面性を損なう虞があるので、乾燥の初期段階では、溶媒が発泡しない程度の温度で乾燥し、乾燥が進んでから高温で乾燥を行うのが好ましい。
【００７１】
支持体から剥離後の乾燥工程では、溶媒の蒸発によってウェブは幅方向に収縮しようとする。高温度で乾燥するほど収縮が大きくなる。この収縮は可能な限り抑制しながら乾燥することが、出来上がったフィルムの平面性を良好にする上で好ましい。この点から、例えば、特開昭６２−４６６２５号公報に示されているような乾燥全工程或いは一部の工程を幅方向にクリップでウェブの幅両端を幅保持しつつ乾燥させる方法（テンター方式）が好ましい。
【００７２】
更には、積極的に幅方向に延伸する方法もあり、本発明では、例えば、特開昭６２−１１５０３５号、特開平４−１５２１２５号、同４−２８４２１１号、同４−２９８３１０号等の公報に記載の延伸方法も使用し得る。
【００７３】
本発明のセルロースアシレートフィルムの乾燥工程における乾燥温度は４０から２５０℃、特に７０から１８０℃が好ましい。使用する溶媒によって乾燥温度、乾燥風量及び乾燥時間が異なり、使用溶媒の種類、組合せに応じて適宜選べばよい。最終仕上がりフィルムの残留溶媒量は２重量％以下、更に０．４重量％以下であることが、寸度安定性が良好なフィルムを得る上で好ましい。
【００７４】
これら流延から後乾燥までの工程は、空気雰囲気下でもよいし窒素ガスなどの不活性ガス雰囲気下でもよい。
【００７５】
本発明のセルロースアシレートフィルムの製造に係わる巻き取り機は一般的に使用されているものでよく、定テンション法、定トルク法、テーパーテンション法、内部応力一定のプログラムテンションコントロール法などの巻き取り方法で巻き取ることができる。
【００７６】
本発明の出来上がり（乾燥後）のセルロースアシレートフィルムの厚さは、使用目的によって異なるが、通常５〜５００μｍの範囲であり、更に４０〜２５０μｍの範囲が好ましく、特に６０〜１２５μｍの範囲が最も好ましい。フィルム厚さの調整は、所望の厚さになるように、ドープ中に含まれる固形分濃度、ダイの口金のスリット間隙、ダイからの押し出し圧力、支持体速度等を調節すればよい。
【００７７】
ここで、置換度及び重量平均重合度の測定方法について述べる。
【００７８】
１）セルロースアシレートのアセチル基と他のアシル基の置換度の測定
置換度は、ＡＳＴＭＤ８１７−９１に準じて行い、ケン化法によって測定するものとする。乾燥したセルロースアシレートを精秤し、アセトンとジメチルスルホキシドとの混合溶媒（容量比４：１）に溶解した後、所定の１Ｎ水酸化ナトリウム水溶液を添加し、２５℃で２時間ケン化する。フェノールフタレインを指示薬として添加し、１Ｎ硫酸（濃度ファクター；Ｆ）で過剰の水酸化ナトリウムを滴定する。また、上記と同様な方法により、ブランクテストを行う。そして、下記に従って置換度を算出する。
【００７９】
Ｔ［Ａ＋Ｂ］＝（Ｅ−Ｍ）×Ｆ／（１０００×Ｗ）
Ａ＝｛１６２．１４×Ｔ［Ａ＋Ｂ］｝／｛１−４２．１４×Ｔ［Ａ＋Ｂ］＋
（１−５６．０６×Ｔ［Ａ＋Ｂ］）×（Ｃｂ／Ｃａ）｝
Ｂ＝Ａ×（Ｃｂ／Ｃａ）
ここで、Ｔ［Ａ＋Ｂ］：全有機酸量（モル／ｇ）
Ｅ：ブランク試験滴定量（ｍｌ）
Ｍ：試料滴定量（ｍｌ）
Ｆ：１Ｎの硫酸のファクター
Ｗ：試料重量（ｇ）
Ｃａ：イオンクロマトグラフィーで測定した酢酸量（モル）
Ｃｂ：イオンクロマトグラフィーで測定した炭素原子数３乃至５の有機酸量（モル）
Ｃｂ／Ｃａ：酢酸と他の有機酸とのモル比
Ａ：アセチル基の置換度
Ｂ：炭素原子数３乃至５のアシル基の置換度
である。
【００８０】
２）セルロースアシレートの重量平均重合度（Ｄｐ）
高速液体クロマトグラフィにより下記条件で重量平均分子量を測定する。
【００８１】
溶媒：アセトン
カラム：ＭＰＷ×１（東ソー（株）製
流量：１．０ｍｌ／分
試料注入量：３００μｌ
標準試料：ポリメチルメタクリレート（重量平均分子量（Ｍｗ）＝１８８，２
００）
温度：２３℃
得られた結果と上記置換度の結果から以下の式により求める。
【００８２】
重量平均重合度（Ｄｐ）＝Ｍｗ／｛（１６２＋４２×Ａ＋（Ｍｏ−１８）×Ｂ｝式中Ｍｗはセルロースアシレートの重量平均分子量、Ａはアセチル基の置換度、Ｂはアセチル基以外のアシル基の置換度及びＭｏはアセチル基以外のアシル基に対応する有機酸の分子量を表す。
【００８３】
【実施例】
以下、実施例を挙げて本発明を詳細に説明するが、本発明の態様はこれに限定されない。
【００８４】
フィルムの残留溶媒量は次のように測定した。
【００８５】
試験フィルム或いはウェブ（Ｕ）を秤量ビンに入れ精秤し、次に前記フィルム或いはウェブを１５０℃で３時間加熱した後、水分を吸わないように室温まで冷却し秤量する。絶乾フィルム或いはウェブの重量（Ｄｒ）として、
残留溶媒量（％）＝｛（Ｕ−Ｄｒ）／Ｄｒ｝×１００
で求めた。
【００８６】
実施例中のドープについては透明性と経時安定性、それにドープの粘度を、またフィルムについては、ヘイズ、引裂強度、引張強度、弾性率及び耐折度を、各測定及び評価方法は以下の方法で行った。なお、ここでフィルムとはセルロースアシレートフィルム製造工程の最終段階の巻き取り工程で巻き取り後切り出した乾燥されたフィルムをいう。
【００８７】
〈ドープの透明性及び経時安定性〉
ドープ（セルロースアシレート溶液）を透明な容器に入れ、目視で作製直後、７２時間後及び１６８時間後の透明性を観察し、同時に容器を逆さまにして溶液の流動性の変化を観察し、次の基準で評価しランク付けした。
【００８８】
Ａ：透明で均一なドープで、容器を逆さにするとスムーズにドープが移動したＢ：僅かに濁りはあるが、透明性はある。容器を逆さまにすると流動性はあるが、移動する界面に若干つぶつぶ状のものが認められる
Ｃ：濁りがあり、不溶解物が認められ、容器を逆さまにするとドープは不均一に移動する
Ｄ：著しく濁り、不溶解物が多く、相分離しており、又は、容器を逆さまにしても流動性がなくゲル状になっている。
【００８９】
〈ヘイズ〉
ＪＩＳ Ｋ−６７１４に従って、ヘイズメーター（１００１ＤＰ型、日本電色工業（株）製）を用いて測定した。
【００９０】
〈引裂強度〉
フィルムを温度２３℃、相対湿度５５％ＲＨに調湿された部屋で４時間調湿した後、試料寸法５０ｍｍ×６４ｍｍに切り出し、ＩＳＯ ６３８３／２−１９８３に従い測定して求めた。
【００９１】
〈引張強度と弾性率〉
フィルムを温度２３℃、相対湿度５５％ＲＨに調湿された部屋で４時間調湿した後、試料巾１０ｍｍ、長さ２００ｍｍに切断し、チャック間距離１００ｍｍにして引っ張り速度１００ｍｍ／分で引っ張り試験を行い求めた。
【００９２】
〈耐折度〉
フィルムを温度２３℃、相対湿度５５％ＲＨに調湿された部屋で４時間調湿した後、試料長さ１２０ｍｍに切り出し、ＩＳＯ ８７７６／２−１９８８に従い、折り曲げによって切断するまでの折り曲げ回数を測定した。
【００９３】
［実施例１］
アセチル基置換度２．７１、プロピオニル基置換度０．１７、重量平均重合度６００のセルロースアセテートプロピオネート１００重量部と、酢酸メチル４７５重量部及びエタノール２５重量部の有機溶媒を、及びトリフェニルホスフェート（ＴＰＰ）１０重量部を蓋付の容器に入れ混合した。混合物を肉厚１００μｍのアルミニウム製容器（内容積１０００ｃｃ）に満たし、空気が残らないようにしてアルミニウム箔で蓋をし、かしめるように密封した。この密閉された容器をゴム製の袋に詰め、軽く脱気後ゴム袋を封入する。このゴム袋をセラミック成型用ゴム製静水圧加圧装置（神戸製鋼製）にセットし、２５℃で１０００ｋｇｆ／ｃｍ²の圧力で２時間加圧した。加圧後、大気圧に戻しゴム袋からアルミニウム容器を取り出し、アルミニウム容器の蓋をとり、ガラス容器に移し、溶解状態を目視観察を行ったところ、セルロースアセテートプロピオネートが全て有機溶媒中に溶解しており、透明な均一なドープが得られた。得られたドープを安積濾紙（株）製の安積濾紙Ｎｏ．２４４を使用して濾過し、溶液流延製膜方法及び装置により、膜厚１２０μｍのセルロースアセテートプロピオネートフィルムを得た。フィルムの残留溶媒量は０．９重量％であった。
【００９４】
［実施例２］
酢酸メチルを３８０重量部、エタノールを２０重量部に変更した以外は実施例１と同様にして膜厚１２０μｍのセルロースアセテートプロピオネートフィルムを得た。フィルムの残留溶媒量は０．８％であった。
【００９５】
［実施例３］
アセチル基の置換度２．３８、プロピオニル基の置換度０．３９及び重量平均重合度５５０のセルロースアセテートプロピオネートに、また有機溶媒を酢酸メチル４００重量部、エタノール７５重量部及び１−ブタノール２５重量部に変更した以外は実施例１と同様にして膜厚１２０μｍのセルロースアセテートプロピオネートを得た。フィルムの残留溶媒量は１．５重量％であった。
【００９６】
［実施例４］
アセチル基の置換度を２．６１、プロピオニル基の置換度を０．３０及び重量平均重合度を５００のセルロースアセテートプロピオネートに変更した以外は実施例１と同様にして膜厚１２０μｍのセルロースアセテートプロピオネートフィルムを得た。フィルムの残留溶媒量は０．９重量％であった。
【００９７】
［実施例５］
有機溶媒として酢酸メチルを２５０重量部及びアセトンを２５０重量部に変更した以外は実施例１と同様にして膜厚１２０μｍのセルロースアセテートプロピオネートフィルムを得た。フィルムの残留溶媒量は０．９重量％であった。
【００９８】
［実施例６］
有機溶媒としてアセトンを５００重量部に変更した以外は実施例１と同様にして膜厚１２０μｍのセルロースアセテートプロピオネートフィルムを得た。フィルムの残留溶媒量は０．９重量％であった。
【００９９】
［比較例１］
外側にジャケットの付いている容器に、アセチル基の置換度２．８８及び重量平均重合度３００のセルロースアセテートプロピオネート１００重量部と、酢酸メチルを５００重量部及びＴＰＰ１０重量部を混合し混合物とした。混合物をゆっくり撹拌しながら、外側のジャケットに−７５℃の冷媒（ＨＦＥ−７１００、住友スリーエム（株）製）を導入し、容器内の混合物を−７０℃に冷却した。混合物を３０分間冷却を続け、次にジャケットから、冷媒を除き、代わりに３０℃の温水をジャケットに導入し、撹拌しながら４０分で混合物を３０℃にし、更に２０分撹拌した。この冷却及び加温の工程を３回繰り返し、ドープを得た。得られたドープを安積濾紙（株）製の安積濾紙Ｎｏ．２４４を使用して濾過し、溶液流延製膜方法及び装置により、膜厚１２０μｍのセルロースアセテートプロピオネートフィルムを得た。フィルムの残留溶媒量は１．０重量％であった。
【０１００】
［比較例２］
酢酸メチルの代わりにアセトンに変更した以外は比較例１と同様にして膜厚１２０μｍのセルロースアシレートフィルムを得た。フィルムの残留溶媒量は０．９重量％であった。
【０１０１】
以上の結果を表１に示した。
【０１０２】
【表１】

【０１０３】
（結果）
表１から明らかなように、本発明のドープは、比較例１及び２の冷却溶解方法により調製したドープと比較して、透明性及び経時安定性が良好であり、更に、本発明のセルロースアシレートフィルムは、透明性、フィルム機械的性質も強く良好であった。
【０１０４】
【発明の効果】
本発明により、塩素系有機溶媒を用いず、しかも冷却溶解方法を使用せず、透明性及び経時安定性の優れたセルロースアシレート溶液を高圧溶解方法により得ることが出来、またこの溶液を用いることにより、透明性、機械的性質の優れたセルロースアシレートフィルムを得ることが出来、高級のハロゲン化銀写真感光材料及び液晶画像表示装置用の支持体をうることが出来る。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for preparing a cellulose acylate solution used for a film useful for a silver halide photographic light-sensitive material, a liquid crystal image display device, and the like, a method for producing a cellulose acylate film, and a cellulose acylate film.
[0002]
[Prior art]
Conventionally, a halogenated hydrocarbon such as methylene chloride has been used as an organic solvent of a cellulose triacetate solution used in producing a cellulose triacetate film used in a silver halide photographic light-sensitive material or a liquid crystal image display device. Methylene chloride (boiling point 41 ° C.) has been conventionally used as a good solvent for cellulose triacetate, and is preferably used because it has a low boiling point in the film formation and drying steps of the production process and is easy to dry. On the other hand, methylene chloride is easy to evaporate due to its low boiling point, and there is a problem that it cannot be completely prevented from being released into the atmosphere because there is some leakage from the sealed equipment and there is a limit to recovery. Recently, protection of the global environment has started to be emphasized, the use of this type of halogenated hydrocarbons has been restricted, and the use of methylene chloride has also been restricted. There is a demand for the development of other solvents.
[0003]
Known organic solvents that are soluble in cellulose acetate include acetone (boiling point: 56 ° C.), methyl acetate (boiling point: 56.3 ° C.), tetrahydrofuran (boiling point: 65.4 ° C.), 1 , 3-dioxolane (boiling point: 75 ° C), nitromethane (boiling point: 101 ° C), 1,4-dioxane (boiling point: 101 ° C), epichlorohydrin (boiling point: 116 ° C), N-methylpyrrolidone (boiling point: 202 ° C), etc. There is. When these organic solvents were actually subjected to a dissolution test, some of them were not necessarily good solvents, and there were few things that could be put to practical use, such as those with a concern of explosion and those with a high boiling point.
[0004]
Among the above organic solvents, acetone with a low boiling point only swells cellulose triacetate by ordinary methods, but did not reach dissolution. In recent years, attempts to make fibers and films by dissolving cellulose triacetate in acetone. Has come to be made.
[0005]
J. et al. M.M. G. Cowie et al., Makromol. chem. 143, 105 (1971), cellulose triacetate (degree of acetylation 60.1-61.3%) is cooled to −80 to −70 ° C. in acetone and then heated to 0.5 to 5 wt. % Dilute solution is reported. Such a method of melting at a low temperature is called a cooling dissolution method. In addition, Kenji Kamide et al. Described spinning technology using a cooling dissolution method in “Dry spinning from cellulose triacetate in acetone” in the Journal of Textile Machinery Society, 34, 57-61 (1981). .
[0006]
Japanese Patent Application Laid-Open Nos. 9-95544 and 9-95557 propose to apply a cooling dissolution method to film production using acetone and other organic solvents against the background of the above technique.
[0007]
In JP-A-9-95538, a cellulose acylate film is dissolved by a cooling dissolution method using an organic solvent selected from ethers other than acetone, ketones or esters, and these films are prepared. 2-methoxyethyl acetate, cyclohexanone, ethyl formate and methyl acetate are preferred. In this method, it is said that the reproducibility of the transparency and stability of the prepared cellulose acylate solution is poor unless the low polymerization degree part of the cellulose acylate is removed in advance.
[0008]
Japanese Patent Laid-Open No. 10-45804 proposes that the cellulose acylate having an acetyl group and an acyl group having 3 or more carbon atoms is soluble in a specific solvent such as acetone or methyl acetate in the cooling dissolution method. Yes.
[0009]
[Problems to be solved by the invention]
The cellulose acylate solution obtained by the above cooling dissolution method is said to obtain mechanical properties equivalent to or higher than cellulose triacetate, but those having a high degree of substitution of acyl groups have insufficient mechanical strength and are substantially In particular, there is a problem that only those having a small substitution degree of acyl group can be used practically. When the substitution degree of the acyl group was small, it was still necessary to dissolve by the cooling dissolution method.
[0010]
Accordingly, an object of the present invention is to prepare a cellulose acylate solution in a state as close to room temperature as possible without using a chlorinated organic solvent such as methylene chloride as a solvent for cellulose acylate and not depending on the cooling dissolution method, It is in providing the method of producing a cellulose acylate film, and the cellulose acylate film made by it.
[0011]
[Means for Solving the Problems]
The above object of the present invention can be achieved by preparing a cellulose acylate solution by the following high-pressure dissolution methods (1) to (12).
[0012]
(1) A mixture containing a cellulose acylate having a hydroxyl group substituted with an acyl group having 3 or more carbon atoms and containing an organic solvent mainly composed of a non-chlorine organic solvent is 10 to 5000 kgf / cm²And the treated mixture at 0.1 to 10 kgf / cm.²Through the process of processing under pressureFilter with filter paperA method for preparing a cellulose acylate solution.
[0013]
(2)The method for preparing a cellulose acylate solution according to (1), wherein the cellulose acylate concentration in the cellulose acylate solution is 10 to 40% by weight.

[0014]
(3)10 to 5000 kgf / cm ² The pressure range of the process to be processed under the pressure of 50 to 4000 kgf / cm ² The method for preparing a cellulose acylate solution according to (1) or (2), wherein

[0015]
(4)10 to 5000 kgf / cm ² (4) The method for preparing a cellulose acylate solution according to any one of (1) to (3), wherein the step of treating under pressure is not heated.
[0016]
(5) The non-chlorine organic solvent is selected from esters having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, and ethers having 3 to 12 carbon atoms.(1) to (4)The method for preparing a cellulose acylate solution according to any one of the above.
[0017]
(6) The non-chlorine organic solvent is methyl acetate or acetone, and any one of them is contained in an amount of 50% by weight or more of the organic solvent, (1) to (5) A method for preparing a cellulose acylate solution.
[0018]
(7) The method for preparing a cellulose acylate solution as described in any one of (1) to (6), wherein the organic solvent contains an alcohol having 1 to 6 carbon atoms.
[0019]
(8) The method for preparing a cellulose acylate solution according to any one of (1) to (7), wherein the pressure is applied by a hydrostatic pressure method.
[0020]
(9) The method for preparing a cellulose acylate solution according to any one of (1) to (8), wherein the cellulose acylate satisfies all of the following formulas (I) to (III):
(I) 2.6 ≦ A + B ≦ 3.0
(II) 2.0 ≦ A <3.0
(III) 0 <B ≦ 0.8
Here, A and B in the formula represent the substitution degree of the acyl group substituted with the hydroxyl group of cellulose, A is the substitution degree of the acetyl group, and B is the substitution degree of the acyl group having 3 or more carbon atoms.
[0021]
(10) The method for preparing a cellulose acylate solution according to any one of (1) to (9), wherein the weight average polymerization degree of the cellulose acylate is from 350 to 800.
[0022]
(11) As described in any one of (1) to (10)Adjusted by adjusting the cellulose acylate solutionA method for producing a cellulose acylate film, wherein a cellulose acylate solution is used to form a film by a solution casting film forming method.
[0023]
(11) A method for producing a cellulose acylate film, wherein the cellulose acylate solution according to any one of (1) to (10) is used to form a film by a solution casting film forming method.
[0024]
(12) A cellulose acylate film formed by the method described in (11).
[0025]
The present invention is described in detail below.
[0026]
The cellulose acylate of the present invention satisfies the following formulas (I) to (III) in terms of the degree of substitution of cellulose with hydroxyl groups.
[0027]
(I) 2.6 ≦ A + B ≦ 3.0
(II) 2.0 ≦ A <3.0
(III) 0 <B ≦ 0.8
In the formula, A and B represent a substituent of an acyl group substituted with a hydroxyl group of cellulose, A is a substitution degree of an acetyl group, and B is a substitution degree of an acyl group having 3 or more carbon atoms. Cellulose has three hydroxyl groups in one glucose unit, and the above number represents the degree of substitution with respect to the hydroxyl group 3.0, and the maximum degree of substitution is 3.0. Cellulose triacetate generally has a substitution degree of A of 2.6 to 2.9 or less (in this case, there is a maximum of 0.4 hydroxyl groups not substituted). The cellulose acylate of the present invention preferably has an acetyl group of 2.0 or more, an acyl group having 3 or more carbon atoms of 0.8 or less, and an unsubstituted hydroxyl group of 0.4 or less. In the case of an acyl group having 3 or more carbon atoms, 0.3 or less is particularly preferable from the viewpoint of physical properties.
[0028]
The degree of substitution can be obtained by calculation by measuring the degree of binding of acetic acid substituted with a hydroxyl group of cellulose and a fatty acid having 3 or more carbon atoms. As a measuring method, it can carry out according to ASTM D-817-91.
[0029]
In the present invention, the number of carbon atoms of the acyl group other than the acetyl group is 3 or more, but it is necessary that the mechanical properties as the film base of the silver halide photographic light-sensitive material, particularly the elastic modulus is large. ~ 6 is preferred. Furthermore, 3-4 are especially preferable. Among these, an n-propionyl group and an n-butyryl group are preferable.
[0030]
The degree of polymerization of the cellulose acylate of the present invention is preferably 350 to 800 in terms of weight average degree of polymerization, and is preferably 370 to 600 in terms of mechanical properties and cost.
[0031]
The cellulose acylate used in the present invention can be prepared, for example, by the method described in JP-A-10-45804. Further, as the raw material cellulose, there are cotton linter and wood pulp, and any of them is preferably used. You may mix and use the cellulose acylate from which a weight average degree of polymerization, a raw material, and a substitution degree differ.
[0032]
The non-chlorine organic solvent of the present invention is an organic solvent substantially free from a chlorinated organic solvent such as methylene chloride, the main component of which is an ester having 3 to 12 carbon atoms, and 3 carbon atoms. It is at least one non-chlorine organic solvent selected from -12 ketones and C3-12 ethers. “Substantially free of chlorinated organic solvents” means that the content in the total organic solvent is 5% by weight or less (preferably 5% by weight or less) in the mixed solvent. Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, pentyl acetate, and 2-ethoxy-ethyl acetate. Examples of the ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone, and ethers having 3 to 12 carbon atoms. Examples thereof include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole.
[0033]
In addition, it is preferable to add an alcohol having 1 to 6 carbon atoms to the organic solvent of the present invention. A cellulose acylate solution in which these alcohols are mixed with the above-mentioned non-chlorine organic solvent (hereinafter, the cellulose acylate solution may be referred to as a dope) flows on the support of the solution casting film forming apparatus during film formation. When the organic solvent begins to evaporate after being stretched, the dope loses its fluidity and is suitable for substantially increasing the film-forming speed and producing a film with good quality such as flatness. Examples of the alcohol having 1 to 6 carbon atoms include methanol, ethanol, propanol, iso-propanol, 1-butanol, t-butanol, 2-methyl-2-butanol, 2-methoxyethanol, 2-butoxyethanol and And cyclohexanol. Two or more of these may be used in combination.
[0034]
As an organic solvent having such an effect, there are cyclic hydrocarbons having 5 to 8 carbon atoms, and these can be preferably used in the same manner as alcohols. Examples include cyclopentane, cyclohexane, cycloheptane and cyclooctane.
[0035]
In addition to the organic solvent of the present invention, the dope used in the present invention may contain fluoroalcohol in an amount of 10% by weight or less of the total organic solvent amount of the present invention to improve the transparency of the film or accelerate the solubility. This is preferable. The fluoroalcohol has a boiling point of 165 ° C or lower, preferably 111 ° C or lower, and more preferably 80 ° C or lower. The fluoroalcohol has about 2 to 10 carbon atoms, preferably about 2 to 8 carbon atoms. The fluoroalcohol is a fluorine atom-containing aliphatic alcohol, which may or may not have a substituent. As the substituent, an aliphatic substituent or an aromatic substituent containing or not containing a fluorine atom is preferable. Such a fluoroalcohol is, for example (the following is the boiling point in parentheses)
2-fluoroethanol (103 ° C.),
2,2,2-trifluoroethanol (80 ° C.),
2,2,3,3-tetrafluoro-1-propanol (109 ° C.),
1,3-difluoro-2-propanol (55 ° C.),
1,1,1,3,3,3-hexa-2-methyl-2-propanol (62 ° C.),
1,1,1,3,3,3-hexafluoro-2-propanol (59 ° C.),
2,2,3,3,3-pentafluoro-1-propanol (80 ° C.),
2,2,3,4,4,4-hexafluoro-1-butanol (114 ° C.),
2,2,3,3,4,4,4-heptafluoro-1-butanol (97 ° C.),
Perfluoro-tert-butanol (45 ° C.),
2,2,3,3,4,4,5,5-octofluoro-1-pentanol (142 ° C.),
2,2,3,3,4,4-hexafluoro-1,5-pentanediol (111.5 ° C.),
3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-1-octanol (95 ° C.),
2,2,3,3,4,5,5,6,6,7,7,8,8,8-pentadecafluoro-1-octanol (165 ° C.),
1- (pentafluorophenyl) ethanol (82 ° C.),
2,3,4,5,6-pentafluorobenzyl alcohol (115 ° C.),
Etc. are included. These fluoroalcohols may be used alone or in combination.
[0036]
A high-pressure dissolution method in which cellulose acylate is dissolved under pressure in an organic solvent containing the non-chlorine organic solvent of the present invention as a main component will be described. First, cellulose acylate is added to an organic solvent mainly composed of a non-chlorine organic solvent in a pressurized container, and the mixture is added to 10 to 5000 kg / cm.²And then processing, followed by 0.1 to 10 kgf / cm²The dope can be prepared by dissolving the cellulose acylate by lowering the pressure to a normal pressure, and preferably by returning to normal pressure.
[0037]
The pressurizing method and pressurizing apparatus of the high-pressure dissolution method of the present invention are not particularly limited as long as the pressurizing apparatus and pressurizing apparatus are used. However, the pressurizing apparatus can easily extract the dope, and 10 ~ 5000kg / cm²Any device can be used as long as the pressure can be applied. The pressurizing pressure of the high-pressure dissolution method of the present invention is 10 to 5000 kg / cm.²The range is preferably 50 to 4000 kg / cm.²More preferably, 100 to 2000 kg / cm²It is. As the pressurizing method and pressurizing apparatus suitable for the present invention, a method and an apparatus used in other industries can be used. For example, a hydrostatic pressurizing method (Cold Isostatic Press, abbreviated as CIP, or rubber used for molding ceramics). The press method is also included in this), which is preferable as a method and equipment capable of safely applying high pressure. This hydrostatic pressure application method and apparatus is preferable because it can uniformly apply hydrostatic pressure to the mixture of cellulose acylate and organic solvent from all directions, and an excellent dissolved cellulose acylate solution can be obtained. is there. As the material of the container for enclosing the mixture in the hydrostatic pressure method, rubber or a metal that can be easily deformed by pressure, such as an aluminum container, may be used. Alternatively, the mixture can be intermittently prepared by sealing the mixture in an easily deformable sealed container such as rubber and moving and transporting the sealed container while applying hydrostatic pressure. Moreover, the means which compresses a mixture by putting a mixture in the container which has a lid | cover which can be slid up and down, and pushing a lid | cover can also be taken. Further, the mixture may be kneaded and extruded using a pressure type extruder. The pressure treatment may be intermittently performed during the preparation of the cellulose acylate solution of the present invention, and the dissolution rate can be increased by repeating the pressure treatment and the reduced pressure (preferably normal pressure treatment). . The pressurizing device may or may not be equipped with a stirring device.
[0038]
In the present invention, when dissolving a mixture of cellulose acylate and an organic solvent, the mixture is allowed to stand before pressurization, for example, after being left in a swollen state for one day and night and then subjected to pressure treatment, immediately after mixing. Although the pressure treatment may be performed, the latter is preferable when there is a margin in the pressure dissolution apparatus.
[0039]
As for the pressure treatment time relating to the preparation of the cellulose acylate solution of the present invention, if the pressure is high, there is no problem in dissolving if it is 1 minute or longer, and the time of more than 120 hours does not impair the purpose of the present invention, The time is too long and the workability is poor, which is not preferable, and therefore it is preferably 120 hours or shorter, more preferably 10 to 15 hours, and particularly preferably 30 to 8 hours.
[0040]
The temperature at which the solution according to the present invention is prepared is not particularly limited, but the object of the present invention can be sufficiently achieved at around room temperature.
[0041]
The concentration of cellulose acylate in the dope of the present invention is adjusted to 10 to 40% by weight. Preferably it is 15 to 35% by weight. In the dissolution stage, it may be 1 to 10% by weight, and may be concentrated to the viscosity of the dope to be cast thereafter. The concentration method is not particularly limited, but for example, a low concentration solution is guided between the cylinder and the rotation trajectory of the inner periphery of the rotating blade and the temperature between the solution and the solution. A method of obtaining a high-concentration solution while evaporating the organic solvent by giving a difference (for example, JP-A-4-259511), blowing a heated low-concentration solution from the nozzle into the container, and hitting the solution from the nozzle to the inner wall of the container The organic solvent is flash-evaporated between them, and the organic solvent is withdrawn from the container, and the high-concentration solution is withdrawn from the bottom of the container (for example, US Pat. Nos. 2,541,012, 2,858,229, and 4). , 414, 341, 4,504, 355, etc.). Thus, the temporal stability of the dope that dissolves at a low concentration and high pressure can be improved, and foreign matters such as undissolved substances can be efficiently removed.
[0042]
Various additives according to the application can be added to the cellulose acylate solution of the present invention in each preparation step. Further, the addition may be performed at any time in the dope preparation step, but may be performed by adding an additive to the final preparation step of the dope preparation step. Cellulose acylate films for silver halide photographic light-sensitive materials are provided with plasticizers, colorants for preventing light piping, or UV inhibitors to improve mechanical properties or impart water resistance, and for liquid crystal display devices. It is preferable to add an antioxidant or the like that imparts heat and humidity resistance.
[0043]
As the plasticizer, phosphoric acid ester, carboxylic acid ester, glycolic acid ester and the like are preferably used. Examples of phosphate esters include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, and tributyl phosphate. Examples of carboxylate esters include dimethyl phthalate. , Diethyl phthalate, dibutyl phthalate, dioctyl phthalate, diethyl hexyl phthalate, acetyl triethyl citrate, acetyl tributyl citrate, butyl oleate, methyl acetyl ricinoleate, dibutyl sebacate, trimellitic acid ester, etc. As triacetin, tributyrin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, Chill phthalyl ethyl glycolate, and the like butyl phthalyl butyl glycolate. Of these, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, diethyl hexyl phthalate, triacetin, and ethyl phthalyl ethyl glycolate are preferable. In particular, triphenyl phosphate, diethyl phthalate, and ethyl phthalyl ethyl glycolate are preferable. These plasticizers may be used alone or in combination of two or more. The addition amount of the plasticizer is preferably 5 to 30% by weight, particularly preferably 8 to 16% by weight, based on the cellulose acylate. These compounds may be added together with cellulose acylate and a solvent during the preparation of the cellulose acylate solution, or may be added during or after the solution preparation.
[0044]
Further, a compound represented by the following general formula (I) (II) or (III) may be added.
[0045]
[Chemical 1]

[0046]
In the general formulas (I), (II), and (III), R is an alkyl group having 1 to 4 carbon atoms. Examples of the compound represented by the general formula (I), (II) or (III) include 2,2′-methylenebis (4,6-di-tert-butylphenyl) sodium phosphate (ADK STAB NA-10, Asahi Denka Co., Ltd.) and bis (p-ethylbenzylidene) sorbitol (NC-4, Mitsui Toatsu Chemical Co., Ltd.) are included.
[0047]
As the antioxidant, those represented by the following general formula (IV) are used.
[0048]
[Chemical formula 2]

[0049]
R in the general formula (IV)₁Represents an alkyl group, R₂, R_ThreeAnd X are a hydrogen atom, alkyl group, alkenyl group, aryl group, heterocyclic group, alkoxy group, alkenoxy group, aryloxy group, alkylthio group, alkenylthio group, arylthio group, heterocyclic oxy group, hydroxy group, amino group, respectively. Represents a group, a carbamoyl group, a sulfamoyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a halogen atom, a nitro group, a cyano group, an acyl group, or an acyloxy group. m represents an integer of 0-2. R₂, R_ThreeAnd X may be the same as or different from each other. Examples of the alkyl group include linear, branched, or cyclic alkyl groups such as methyl, ethyl, propyl, iso-propyl, tert-butyl, cyclohexyl, tert-hexyl, tert-octyl, dodecyl, hexadecyl, octadecyl, and benzyl. The alkenyl group represents a linear, branched, or cyclic alkenyl group such as vinyl, allyl, 2-pentenyl, cyclohexenyl, hexenyl, dodecenyl, octadecenyl, and the aryl group includes, for example, phenyl, Represents a benzene monocyclic or condensed polycyclic aryl group such as naphthyl and anthranyl, and the heterocyclic group includes, for example, a nitrogen atom such as furyl, pyrrolyl, imidazolyl, pyridyl, purinyl, chromanyl, pyrrolidyl, morpholinyl, sulfur atom, oxygen At least of atoms One represents a group consisting of 5-7 membered ring containing. Of these, hindered phenol compounds are preferred, 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], octadec -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) -isocyanate Examples include nurate. 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, hydrazine-based metal deactivators such as N, N′-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine and tris (2,4-di-tert A phosphorus processing stabilizer such as -butylphenyl) phosphite may be used in combination. The amount of these compounds added is preferably 1 ppm to 1.0% by weight, more preferably 10 to 1000 ppm, based on the cellulose acylate.
[0050]
Examples of the coloring agent for preventing light piping include compounds represented by the following general formulas (V) and (VI).
[0051]
[Chemical 3]

[0052]
In the formulas (V) and (VI), X represents an oxygen atom or NR_{twenty three}Represents. R₁~ R₈, R₁₂~ R_{twenty three}Are hydrogen atom, hydroxyl group, aliphatic group, aromatic group, heterocyclic group, halogen atom, cyano group, nitro group, COR, respectively.₉, COOR₉, NR₉R_Ten, NR_TenCOR₁₁, NR_TenSO₂R₁₁, CONR₉R_Ten, SO₂NR₉R_Ten, COR₁₁, SO₂R₁₁, OCOR₁₁, NR₉CONR_TenR₁₁, CONHSO₂R₁₁Or SO₂NHCOR₁₁Represents R₉, R_TenEach represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group;₁₁Represents an aliphatic group, an aromatic group, or a heterocyclic group.
[0053]
R₁~ R_{twenty three}Is an alkyl group having 1 to 20 carbon atoms (for example, methyl, ethyl, n-butyl, isopropyl, 2-ethylhexyl, n-decyl, n-octadecyl), cyclohexane having 1 to 20 carbon atoms. Represents an alkyl group (for example, cyclobenzyl, cyclohexyl) or an allyl group, and these further represent a substituent (for example, a halogen atom, a hydroxyl group, a cyano group, a nitro group, a carboxylic acid group, an aryl group having 6 to 10 carbon atoms, a carbon number) An amino group having 0 to 20 carbon atoms, an amide group having 1 to 20 carbon atoms, a carbamoyl group having 1 to 20 carbon atoms, an ester group having 2 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms or an aryloxy group; It may have a 20 sulfonamido group, a sulfamoyl group having 0 to 20 carbon atoms, or a 5- or 6-membered heterocyclic ring.₁~ R_{twenty three}Represents an aryl group such as phenyl or naphthyl having 6 to 10 carbon atoms, and the above-described substituents and methyl, ethyl, n-butyl, tert-butyl, octyl having 1 to 20 carbon atoms. It may have a substituent consisting of an alkyl group such as R₁~ R₁₁The heterocyclic group represented by represents a 5- or 6-membered heterocyclic ring and may have the above-described substituent. Preferred examples (V-1) to (V-25) and (VI-1) to (VI-4) of the compounds represented by the general formulas (V) and (VI) are shown in the following chemical formulas 4 to 9. .
[0054]
[Formula 4]

[0055]
[Chemical formula 5]

[0056]
[Chemical 6]

[0057]
[Chemical 7]

[0058]
[Chemical 8]

[0059]
[Chemical 9]

[0060]
The content of the colorant is preferably from 10 to 1000 ppm, more preferably from 50 to 500 ppm, by weight with respect to cellulose acylate. By containing the colorant in this way, light piping of the cellulose acylate film can be reduced, and yellowness can be improved. These compounds may be added together with cellulose acylate and a solvent during the preparation of the cellulose acylate solution, or may be added during or after the solution preparation.
[0061]
In addition, various additives may be further added to the cellulose acylate solution of the present invention as necessary at any stage after preparation of the solution. Additives include heat stabilizers such as ultraviolet absorbers, kaolin, talc, diatomaceous earth, quartz, calcium carbonate, barium sulfate, titanium oxide, inorganic fine particles such as alumina, alkaline earth metal salts such as calcium and magnesium, Antistatic agents, flame retardants, lubricants, oils, etc.
[0062]
A method for forming a cellulose acylate film using the dope of the present invention will be described.
[0063]
As equipment for producing the cellulose acylate film of the present invention, a solution casting film forming method conventionally used for producing a cellulose acylate film can be used. The outline of the equipment and the manufacturing method will be described. The dope prepared by the above-described preparation apparatus is sent to the pressurizing die through a pressurizing quantitative gear pump capable of quantitatively feeding the liquid with high accuracy by, for example, the rotational speed. The dope fed from the precision gear pump to the pressure die is uniformly cast from the die (slit) of the pressure die onto the endlessly rotating support. As a web), the film is dried while being passed through a rotating roll group, and the dried film is wound up to a predetermined length by a winder after conveyance.
[0064]
The casting method useful in the present invention includes a method in which the prepared dope is uniformly extruded onto a support from a pressure die, and a doctor blade that adjusts the film thickness of the dope once cast on the support with a blade. There is a casting apparatus such as a method or a method using a reverse roll coater that adjusts with a reverse rotating roll, but a method using a pressure die is preferred. The pressure die includes a coat hanger type and a T die type, and any of them can be preferably used. In addition to the methods mentioned here, various methods for casting a cellulose acylate from a conventionally known cellulose acylate solution (for example, JP-A-61-94724, JP-A-61-148013, JP-A-Hei. 4-85011, 4-286611, 5-185443, 5-185445, 6-278149, 8-207210, etc.) can be preferably used, and the solvent used By setting each condition in consideration of the difference in boiling point, etc., the same effects as described in the respective publications can be obtained.
[0065]
The endlessly running support used for producing the cellulose acylate film of the present invention includes a drum whose surface is mirror-finished by chrome plating and a stainless steel belt whose surface is mirror-finished by surface polishing (even though it is called a band) Good) is used.
[0066]
The arrangement of the pressure die used for production of the cellulose acylate film of the present invention on the support may be one or two or more. Preferably 1 or 2 groups. When two or more units are installed, the dope amount to be cast may be divided into various ratios for each die, and the dope is fed to the die from each of a plurality of precision quantitative gear pumps.
[0067]
The drying of the dope on the support relating to the production of the cellulose acylate film of the present invention is generally carried out by applying hot air from the surface side of the drum or belt, that is, the surface of the web on the support, A method of applying hot air from the back side, a liquid heat transfer method of controlling the surface temperature by heating the drum or belt by heat transfer by contacting the temperature-controlled liquid from the back side opposite to the belt or drum dope casting surface However, the backside liquid heat transfer system is preferred.
[0068]
The surface temperature of the support before casting may be any number as long as it is not higher than the boiling point of the solvent used for the dope. However, in order to promote drying and to lose fluidity on the support, the temperature may be set to 1 to 10 ° C. lower than the boiling point of the lowest boiling solvent used. preferable.
[0069]
The speed at which the cellulose acylate film is produced varies depending on the length of the belt, the drying method, the composition of the dope solvent, etc., but is almost determined by the amount of residual solvent at the time when the web is peeled from the belt. In other words, if the solvent concentration in the vicinity of the belt surface in the thickness direction of the dope film is too high, the dope remains on the belt when it is peeled off, which hinders the next casting. This is because the web strength is required to withstand the peeling force. The amount of residual solvent at the time of peeling differs depending on the drying method on the belt or drum, and the method of transferring heat from the belt or drum back is more effective than the method of drying by blowing air from the dope surface. The amount can be reduced.
[0070]
Drying the web related to the production of the cellulose acylate film of the present invention (Here, the web is referred to as the web from the peeled dope film to the film, but the boundary is not clear) The method is described. The web peeled off at the peeling position immediately before the support makes one round is conveyed in a zigzag-like roll group alternately, or both ends of the peeled web are gripped by clips and contactlessly made. Drying is performed by a method of applying a wind at a predetermined temperature to both surfaces of the web being transported or a method using a heating means such as a microwave while transporting by a transport method. Since rapid drying may impair the flatness of the web, it is preferable to dry at a temperature at which the solvent does not foam in the initial stage of drying, and to dry at a high temperature after the drying proceeds.
[0071]
In the drying process after peeling from the support, the web tends to shrink in the width direction by evaporation of the solvent. Shrinkage increases with drying at higher temperatures. In order to improve the flatness of the finished film, it is preferable to dry while suppressing the shrinkage as much as possible. From this point, for example, a method of drying the whole drying process or a part of the process as shown in Japanese Patent Application Laid-Open No. 62-46625 while holding the width at both ends of the web with a clip in the width direction (tenter method) ) Is preferred.
[0072]
Further, there is a method of positively stretching in the width direction. In the present invention, for example, JP-A-62-115035, JP-A-4-152125, JP-A-4284221, JP-A-4-298310, etc. The stretching method described in 1 can also be used.
[0073]
The drying temperature in the drying step of the cellulose acylate film of the present invention is preferably 40 to 250 ° C, particularly preferably 70 to 180 ° C. The drying temperature, the amount of drying air, and the drying time vary depending on the solvent used, and may be appropriately selected according to the type and combination of the solvents used. The amount of residual solvent in the final finished film is preferably 2% by weight or less, and more preferably 0.4% by weight or less in order to obtain a film having good dimensional stability.
[0074]
These steps from casting to post-drying may be performed in an air atmosphere or an inert gas atmosphere such as nitrogen gas.
[0075]
The winder relating to the production of the cellulose acylate film of the present invention may be a commonly used winder such as a constant tension method, a constant torque method, a taper tension method, a program tension control method with a constant internal stress. It can be wound up by the method.
[0076]
The thickness of the finished cellulose acylate film of the present invention (after drying) varies depending on the purpose of use, but is usually in the range of 5 to 500 μm, more preferably in the range of 40 to 250 μm, and most preferably in the range of 60 to 125 μm. preferable. The film thickness may be adjusted by adjusting the solid content concentration contained in the dope, the slit gap of the die base, the extrusion pressure from the die, the support speed, and the like so as to obtain a desired thickness.
[0077]
Here, a method for measuring the degree of substitution and the weight average degree of polymerization will be described.
[0078]
1) Measurement of substitution degree of acetyl group and other acyl groups of cellulose acylate
The degree of substitution is determined according to ASTM D817-91 and measured by a saponification method. The dried cellulose acylate is precisely weighed and dissolved in a mixed solvent of acetone and dimethyl sulfoxide (volume ratio 4: 1), and then a predetermined 1N aqueous sodium hydroxide solution is added and saponified at 25 ° C. for 2 hours. Phenolphthalein is added as an indicator and excess sodium hydroxide is titrated with 1N sulfuric acid (concentration factor; F). Further, a blank test is performed by the same method as described above. Then, the degree of substitution is calculated according to the following.
[0079]
T [A + B] = (EM) × F / (1000 × W)
A = {162.14 × T [A + B]} / {1-42.14 × T [A + B] +
(1-56.06 × T [A + B]) × (Cb / Ca)}
B = A × (Cb / Ca)
Here, T [A + B]: Total organic acid amount (mol / g)
E: Blank test titration (ml)
M: Sample titration (ml)
F: 1N sulfuric acid factor
W: Sample weight (g)
Ca: Amount of acetic acid (mol) measured by ion chromatography
Cb: amount of organic acid having 3 to 5 carbon atoms (mol) measured by ion chromatography
Cb / Ca: molar ratio of acetic acid to other organic acids
A: Degree of substitution of acetyl group
B: Degree of substitution of acyl group having 3 to 5 carbon atoms
It is.
[0080]
2) Weight average polymerization degree of cellulose acylate (Dp)
The weight average molecular weight is measured by high performance liquid chromatography under the following conditions.
[0081]
Solvent: Acetone
Column: MPW × 1 (manufactured by Tosoh Corporation)
Flow rate: 1.0 ml / min
Sample injection volume: 300 μl
Standard sample: polymethyl methacrylate (weight average molecular weight (Mw) = 188,2
00)
Temperature: 23 ° C
It calculates | requires by the following formula | equation from the obtained result and the result of the said substitution degree.
[0082]
Weight average degree of polymerization (Dp) = Mw / {(162 + 42 × A + (Mo-18) × B) where Mw is the weight average molecular weight of cellulose acylate, A is the substitution degree of acetyl group, and B is acyl other than acetyl group The degree of group substitution and Mo represent the molecular weight of an organic acid corresponding to an acyl group other than an acetyl group.
[0083]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the aspect of this invention is not limited to this.
[0084]
The residual solvent amount of the film was measured as follows.
[0085]
The test film or web (U) is placed in a weighing bottle and weighed. Then, the film or web is heated at 150 ° C. for 3 hours, then cooled to room temperature and weighed so as not to absorb moisture. Absolutely dry film or web weight (Dr)
Residual solvent amount (%) = {(U−Dr) / Dr} × 100
I asked for it.
[0086]
Transparency and stability over time for the dope in the examples, and viscosity of the dope, and for the film, haze, tear strength, tensile strength, elastic modulus, and folding resistance are measured and evaluated by the following methods. I went there. In addition, a film means the dried film cut out after winding up by the winding process of the last stage of a cellulose acylate film manufacturing process here.
[0087]
<Transparency of dope and stability over time>
Put the dope (cellulose acylate solution) in a transparent container and visually observe the transparency immediately after production, 72 hours and 168 hours later, and at the same time, observe the change in fluidity of the solution by turning the container upside down. It was evaluated and ranked according to the criteria.
[0088]
A: Transparent and uniform dope, and the dope moved smoothly when the container was inverted. B: Slight turbidity but transparency. If the container is turned upside down, it has fluidity, but the moving interface is slightly crushed.
C: There is turbidity, insoluble matter is observed, and the dope moves unevenly when the container is turned upside down
D: Remarkably turbid, a lot of insoluble matter, phase-separated, or even if the container is turned upside down, it is not fluid and gelled.
[0089]
<Haze>
According to JIS K-6714, it measured using the haze meter (1001DP type, Nippon Denshoku Industries Co., Ltd. product).
[0090]
<Tear strength>
The film was conditioned for 4 hours in a room conditioned at a temperature of 23 ° C. and a relative humidity of 55% RH, cut into a sample size of 50 mm × 64 mm, and measured according to ISO 6383 / 2-1983.
[0091]
<Tensile strength and elastic modulus>
The film was conditioned at a temperature of 23 ° C. and a relative humidity of 55% RH for 4 hours, then cut to a sample width of 10 mm and a length of 200 mm, a distance between chucks of 100 mm, and a tensile test at a pulling speed of 100 mm / min. And asked.
[0092]
<Folding resistance>
The film was conditioned for 4 hours in a room conditioned at a temperature of 23 ° C. and a relative humidity of 55% RH, then cut into a sample length of 120 mm, and the number of folds until it was cut by bending in accordance with ISO 8776 / 2-1988 was measured. did.
[0093]
[Example 1]
100 parts by weight of cellulose acetate propionate having an acetyl group substitution degree of 2.71, a propionyl group substitution degree of 0.17 and a weight average polymerization degree of 600, an organic solvent of methyl acetate 475 parts by weight and ethanol 25 parts by weight, and triphenyl 10 parts by weight of phosphate (TPP) was placed in a container with a lid and mixed. The mixture was filled in an aluminum container (internal volume 1000 cc) having a wall thickness of 100 μm, covered with aluminum foil so that no air remained, and sealed so as to be caulked. The sealed container is packed in a rubber bag, and after light deaeration, the rubber bag is sealed. This rubber bag is set in a ceramic hydrostatic pressurizing device (made by Kobe Steel) for ceramic molding and 1000 kgf / cm at 25 ° C.²For 2 hours. After pressurization, return to atmospheric pressure, take out the aluminum container from the rubber bag, remove the lid of the aluminum container, transfer it to a glass container, and visually observe the dissolved state. All cellulose acetate propionate is dissolved in the organic solvent. Thus, a transparent and uniform dope was obtained. The obtained dope was used as Azumi filter paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. A cellulose acetate propionate film having a film thickness of 120 μm was obtained by a solution casting film forming method and apparatus. The amount of residual solvent in the film was 0.9% by weight.
[0094]
[Example 2]
A cellulose acetate propionate film having a film thickness of 120 μm was obtained in the same manner as in Example 1 except that 380 parts by weight of methyl acetate and 20 parts by weight of ethanol were changed. The amount of residual solvent in the film was 0.8%.
[0095]
[Example 3]
Cellulose acetate propionate having a substitution degree of acetyl group of 2.38, a substitution degree of propionyl group of 0.39 and a weight average polymerization degree of 550, and an organic solvent of 400 parts by weight of methyl acetate, 75 parts by weight of ethanol and 1-butanol 25 A cellulose acetate propionate having a film thickness of 120 μm was obtained in the same manner as in Example 1 except that the amount was changed to parts by weight. The amount of residual solvent in the film was 1.5% by weight.
[0096]
[Example 4]
Cellulose acetate with a film thickness of 120 μm as in Example 1 except that the substitution degree of the acetyl group is 2.61, the substitution degree of the propionyl group is 0.30, and the weight average polymerization degree is 500 cellulose acetate propionate. A propionate film was obtained. The amount of residual solvent in the film was 0.9% by weight.
[0097]
[Example 5]
A cellulose acetate propionate film having a film thickness of 120 μm was obtained in the same manner as in Example 1 except that methyl acetate was changed to 250 parts by weight and acetone was changed to 250 parts by weight as the organic solvent. The amount of residual solvent in the film was 0.9% by weight.
[0098]
[Example 6]
A cellulose acetate propionate film having a thickness of 120 μm was obtained in the same manner as in Example 1 except that acetone was changed to 500 parts by weight as the organic solvent. The amount of residual solvent in the film was 0.9% by weight.
[0099]
[Comparative Example 1]
In a container with a jacket on the outside, 100 parts by weight of cellulose acetate propionate having a substitution degree of acetyl group of 2.88 and a weight average polymerization degree of 300, 500 parts by weight of methyl acetate and 10 parts by weight of TPP were mixed with did. While the mixture was slowly stirred, -75 ° C refrigerant (HFE-7100, manufactured by Sumitomo 3M Co.) was introduced into the outer jacket, and the mixture in the container was cooled to -70 ° C. The mixture was allowed to cool for 30 minutes, then the refrigerant was removed from the jacket, and hot water at 30 ° C. was introduced into the jacket instead, and the mixture was brought to 30 ° C. with stirring for 40 minutes and stirred for an additional 20 minutes. This cooling and heating process was repeated three times to obtain a dope. The obtained dope was used as Azumi filter paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. A cellulose acetate propionate film having a film thickness of 120 μm was obtained by a solution casting film forming method and apparatus. The amount of residual solvent in the film was 1.0% by weight.
[0100]
[Comparative Example 2]
A cellulose acylate film having a thickness of 120 μm was obtained in the same manner as in Comparative Example 1 except that acetone was used instead of methyl acetate. The amount of residual solvent in the film was 0.9% by weight.
[0101]
The above results are shown in Table 1.
[0102]
[Table 1]

[0103]
(result)
As is clear from Table 1, the dope of the present invention has better transparency and stability over time than the dope prepared by the cooling dissolution method of Comparative Examples 1 and 2, and further the cellulose acid of the present invention. The rate film was excellent in transparency and film mechanical properties.
[0104]
【The invention's effect】
According to the present invention, a cellulose acylate solution excellent in transparency and stability over time can be obtained by a high-pressure dissolution method without using a chlorinated organic solvent and without using a cooling dissolution method, and using this solution. Thus, a cellulose acylate film having excellent transparency and mechanical properties can be obtained, and a high-grade silver halide photographic material and a support for a liquid crystal image display device can be obtained.

Claims (2)

Do not heat a mixture containing a cellulose acylate having a hydroxyl group substituted with an acyl group having 3 or more carbon atoms and containing an organic solvent mainly composed of a non-chlorine organic solvent under a pressure of 10 to 5000 kgf / cm ^2. A method for preparing a cellulose acylate solution, comprising: a step of treating, and a step of treating the treated mixture under a pressure of 0.1 to 10 kgf / cm ² , followed by filtration with filter paper. Adjust the cellulose acylate solution by adjusting a cellulose acylate solution according to claim 1, using the cellulose acylate solution, method for producing a cellulose acylate film, which comprises a film by solution casting film method .