JP2004029660A - Manufacturing method for optical film, optical film, and polarizing plate and display device provided with optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film with less stripe irregularities and cracks, its manufacturing method, and a polarizing plate and a display device using it. <P>SOLUTION: In the process of casting a resin solution on a metal supporting body by a solution casting film forming method, drying a peeled film while clamping both width end parts and controlling a width dimension, drying it until the residual solvent amount of the film becomes 1 mass % or less further and winding it, the ratio (A/B) of a shrinkage degree A in a width direction indicated by an expression (1) and the shrinkage degree B in a carrying direction indicated by an expression (2) is 2.0-10.0, the shrinkage degree B is turned to -0.5% or lower, and a long-length resin film is manufactured. A metal oxide layer is formed on it directly or through another coating layer. <P>COPYRIGHT: (C)2004,JPO

Description

上記各組成を、順次密閉容器中に投入し、釜内温度を７０℃まで昇温した後、７０℃で３時間攪拌を行って、各組成物を完全に溶解した。その後、攪拌を停止し、液温を４３℃まで下げてドープを調製した後、直ちに連結した配管を経て後述の濾過工程に送液し、絶対濾過精度０．００５ｍｍの濾紙を用い、濾過流量３００Ｌ／ｍ^２・時、濾圧１．０×１０^６Ｐａで濾過を行った。
【０２１４】
《セルロースエステルフィルム１〜９の作製》
上記調製したドープを、図２に記載のテンター乾燥装置を有する溶液流延製膜セルロースエステルフィルム製造装置を用いて、流延及び乾燥を行いセルロースエステルフィルムを作製した。但し、図２に記載の第１番目のロール乾燥装置６を除いたものを使用した。
【０２１５】
上記調製したドープ液を、ダイ２を通して、ステンレスベルト製の金属支持体１の上に流延し、ステンレスベルトの温度を２５℃に制御し、フィルムＦ側の乾燥工程４からは４５℃の風を１０ｍ／秒の風速で斜めにあて、ステンレスベルト側の乾燥工程３からは、前半を４０℃の風を１０ｍ／秒で垂直にあてフィルムを乾燥し、フィルム中の残留溶媒量が２５質量％になるまで溶媒を蒸発した後、剥離ロール５にて剥離した。
【０２１６】
次いで、テンター乾燥装置８及びロール乾燥装置９にフィルムを導入して、テンター乾燥装置８にて、幅保持しながら１０５℃で乾燥し、続いてフィルムを千鳥状に配置したロール乾燥装置９で１２０℃で乾燥し、巻取り部７の巻取り機７２で巻き取り、最終的に２０℃に冷却して、厚さ６０μｍ、幅１．４ｍのセルロースエステルフィルム１（フィルム試料１ともいう）を作製した。なお、上記全工程を通じてフィルムの搬送時の張力として、１９６Ｎ／幅となるように、ステンレスベルトの搬送速度及び巻取り機の巻取り速度を適宜調整した。
【０２１７】
次いで、上記フィルム試料１の作製において、幅手方向の伸縮率Ａ、搬送方向の伸縮率Ｂ、その比（Ａ／Ｂ）が表１に記載の値となるように、各搬送張力条件、剥離時の残留溶媒量、テンターでの延伸条件、乾燥温度及び膜厚を適宜調整して、セルロースエステルフィルム２〜９（フィルム試料２〜９）を作製した。
【０２１８】
（幅手方向の伸縮率Ａ、搬送方向の伸縮率Ｂの測定）
幅手方向の伸縮率Ａ及び搬送方向の伸縮率Ｂは下式に従い測定した。
【０２１９】
式（１）
幅手方向の伸縮率Ａ＝（巻き取り時のフィルム幅／金属支持体上のフィルム幅−１）×１００（％）
式（２）
搬送方向の伸縮率Ｂ＝（巻き取り時のフィルム搬送速度／金属支持体上のフィルム搬送速度−１）×１００（％）
上記式（１）において、図２に記載の金属支持体上のフィルムの幅方向に一定幅のマーキングを行った。次いで、テンター乾燥装置８、ロール乾燥装置６、９を経て、フィルムの残留溶媒量が１質量％以下になるまで乾燥させた後、巻取り部７の巻取り機７２の直前で、試料をサンプリングし、そのマーキングの長さをメジャーにより測定し、これを用いて幅手方向の伸縮率Ａを算出した。また、金属支持体上でのフィルム搬送速度及び巻き取り時のフィルム搬送速度は、１９６Ｎ／幅の張力で搬送した際に、搬送しているフィルムが弛まず全ての搬送ロールが正常に追従している状態で、フィルムが過度に引っ張られないように、あるいはフィルム端が過度の張力で折れジワが発生しないように搬送速度を最適に調整し、その時の搬送速度を求めた。
【０２２０】
《セルロースエステルフィルムの評価》
以上のようにして作製した各セルロースエステルフィルムについて、以下の方法に従って、リターデーション値Ｒｏ、遅相軸角度θの測定及び寸法安定性の評価を行った。
【０２２１】
（平均膜厚ｄ、リターデーション値Ｒｏ、遅相軸角度θの測定）
リターデーション値Ｒｏの測定には、自動副屈折計ＫＯＢＲＡ−２１ＡＤＨ（王子計測機器社製）を用いて、２３℃、５５％ＲＨの環境下で測定し、キーエンス社製のレーザフォーカス変位計ＬＴ−８０１０によりフィルムの膜厚を測定し、その平均膜厚ｄを求め、前述の方法に従って、試料の幅手方向で１０箇所測定し、リターデーション値Ｒｏの最大値及び搬送方向の遅相軸角度θを０度としたときの幅手方向の遅相軸角度θの最大値を測定した。測定結果を表１に示す。
【０２２２】
【表１】

【０２２３】
このセルロースエステルフィルム１〜９上に、下記のクリアハードコート層を形成し、さらにその上にプラズマ処理で酸化錫層を形成し、層構成がセルロースエステルフィルム／クリアハードコート層／酸化錫層となる光学フィルム１〜９を作製した。
【０２２４】
（クリアハードコート層）
セルロースエステルフィルムのＢ面側（ステンレスベルトにウェブが接していた側のフィルムの面）に下記のクリアハードコート層塗布組成物を液膜厚が１３μｍとなるように押し出しコーターで塗布し、次いで８０℃に設定された乾燥部で乾燥した後、１２０ｍＪ／ｃｍ^２で紫外線照射し、乾燥膜厚で３μｍの中心線平均粗さ（Ｒａ）１３ｎｍのクリアハードコート層を設けた。
【０２２５】

（酸化錫層）
大気圧プラズマＣＶＤによりセルロースエステルフィルム上に酸化錫層（金属酸化物層）を形成した。大気圧プラズマ放電処理は図３に記載の装置を使用した。ロール電極には、シリコンオイルを循環させることによる冷却機能を有するステンレス製ジャケットロール母材を用いた。
【０２２６】
これにセラミック溶射によりアルミナを１ｍｍ被覆し、その上にテトラメトキシシランを酢酸エチルで希釈した溶液を塗布乾燥後、紫外線照射により硬化させて封孔処理を行いＲｍａｘ、１μｍの誘電体を有するロール電極を製作しアース（接地）した。
【０２２７】
一方、対向電極としては、中空のステンレスパイプに対し、上記同様の誘電体を同条件にて被覆し、相対する電極群とした。プラズマＣＶＤ処理装置の電源は、パール工業製高周波電源を使用し、連続周波数を２ＭＨｚとし、４Ｗ／ｃｍ^２の電力を供給した。但し、ロール電極は、ドライブを用いて長尺樹脂フィルムの搬送に同期して回転させた。
【０２２８】
なお、電極間隙は２ｍｍ、反応ガスの圧力を大気圧に対して＋１ｋＰａとして膜厚０．１μｍの金属酸化物層（酸化錫層、表面比抵抗１０^１０Ω／ｃｍ^２未満）を形成した。プラズマ放電処理に用いた反応ガスの組成を以下に記す。
【０２２９】
〈金属酸化物層形成用反応ガス〉
不活性ガス（ヘリウム）　　　　　　　　　　　　　　　　９９．２体積％
反応ガス（酸素ガス）　　　　　　　　　　　　　　　　　　０．４体積％
反応ガス（テトラブチル錫蒸気）　　　　　　　　　　　　　０．４体積％
作製した光学フィルムについて、以下の方法に従って、端部のクラック及び筋ムラを評価した。評価の結果を表２に示す。
【０２３０】
（クラック）
光学フィルムを８０℃、９０％ＲＨで７２時間処理し、フィルム端部より１０ｃｍの部分のフィルム表面に形成された金属酸化物層（反射防止層）に発生したクラックを目視及び顕微鏡で観察した。評価ランクは以下の通りである。
【０２３１】
◎：クラックはほとんど認められず、透明性に優れる
○：クラックは認められるが、白濁はない
△：クラックが認められ、僅かに白濁している
×：著しくクラックが入り、白濁している
（筋ムラ）
光学フィルムの幅手の端部に発生する筋状のムラを目視で下記のように評価した。
【０２３２】
◎：長尺方向に１００ｍ以上で目視で確認されるムラは認められない
○：端部より１０ｃｍ程度の部分に数１０ｍごとに弱いムラが認められる
△：端部より１０ｃｍ程度の部分に断続的にムラが認められる
×：端部より１０ｃｍ程度の部分に断続的に強いムラが認められる。
【０２３３】
【表２】

【０２３４】
表２より明らかなように、本発明で規定する前記式（１）で表される幅手方向の伸縮率Ａと前記式（２）で表される搬送方向の伸縮率Ｂとの比（Ａ／Ｂ）が、２．０〜１０．０で、かつ搬送方向の伸縮率Ｂが−０．５％以下であるセルロースエステルフィルムを用いて、その上に金属酸化物層を形成した光学フィルムは端部でのクラックの発生が抑制され、端部での筋状ムラの発生が少ないことが確認された。
【０２３５】
実施例２
〈防眩層の形成〉
実施例１で作製したセルロースエステルフィルム１〜９の一方の面に、下記に従って防眩層（紫外線硬化樹脂層）を形成した。
【０２３６】

を溶媒（酢酸エチル）にてホモジナイザーにより混合して揮発分濃度５０質量％の均質な分散液を調製した。
【０２３７】
これを上記フィルム上に塗布し、９０℃で２分間乾燥させた後、１１０ｍＪ／ｃｍ^２の紫外線を照射して硬化させ膜厚３μｍの防眩層を形成した。これを、５０℃の２ｍｏｌ／ＬのＮａＯＨ水溶液に９０秒間浸漬して、アルカリ処理（鹸化）した後、水洗・乾燥させた。
【０２３８】
〈反射防止層の形成〉
上記作製した防眩層の上に、下記層（金属酸化物層）を順に形成し反射防止層を形成し、光学フィルム１０〜１８を得た。
【０２３９】
（反射防止層）
酸化チタン層（屈折率２．１０、膜厚０．０２μｍ）
酸化ケイ素層（屈折率１．４５、膜厚０．０３μｍ）
酸化チタン層（屈折率２．１０、膜厚０．１２μｍ）
酸化ケイ素層（屈折率１．４５、膜厚０．０８μｍ）
実施例１で使用したプラズマ放電処理装置を使用し、金属酸化物層形成用反応ガスとして以下のものを用いた以外は実施例１と同様にして上記酸化物層を形成した。
【０２４０】
〈酸化チタン層形成用反応ガス〉
ヘリウム　　　　　　　　　　　　　　　　　　　　　　　９９．４体積％
酸素　　　　　　　　　　　　　　　　　　　　　　　　　　０．３体積％
テトライソプロポキシチタン　　　　　　　　　　　　　　　０．３体積％
〈酸化ケイ素層形成用反応ガス〉
ヘリウム　　　　　　　　　　　　　　　　　　　　　　　９９．３体積％
酸素　　　　　　　　　　　　　　　　　　　　　　　　　　０．４体積％
テトラエトキシシラン　　　　　　　　　　　　　　　　　　０．３体積％
作製した光学フィルムについて、実施例１と同様にして、端部のクラック及び筋ムラを評価した。評価の結果を表３に示す。
【０２４１】
【表３】

【０２４２】
実施例３
《偏光板の作製》
実施例２で作製した光学フィルム１０〜１８を用いて、下記に記載の方法に従って、それぞれ偏光板１０Ａ〜１８Ａを作製した。
【０２４３】
厚さ１２０μｍのポリビニルアルコールフィルムを、沃素１ｋｇ、ホウ酸４ｋｇを含む水溶液１００ｋｇに浸漬し、５０℃で６倍に延伸して偏光膜を作った。この偏光膜の片面に、光学フィルム１０を使用し、もう一方の面に光学フィルム１０の基材として使用したセルロースエステルフィルム（光学フィルム１０の場合はセルロースエステルフィルム１）を下記アルカリケン化処理を行った後、完全ケン化型ポリビニルアルコール５％水溶液を粘着剤として各々貼り合わせ長尺偏光板１０Ａを作製した。
【０２４４】

上記条件で各セルロースエステルフィルムを、ケン化、水洗、中和、水洗の順に行い、次いで８０℃で乾燥を行った。
【０２４５】
光学フィルム１０を光学フィルム１１〜１８に変更し、セルロースエステルフィルムもそれに用いたセルロースエステルフィルム２〜９に変更し、偏光板１１Ａ〜１８Ａを得た。
【０２４６】
本発明に係る偏光板１０Ａ〜１５Ａは端部までムラやクラックが少ないため、２０型用以上のサイズに切り出しても、歩留まりに優れていた。これに対して、比較の偏光板１６Ａ〜１８Ａは端部に筋ムラが目立ち、またクラックも著しいためこの部分が使用できなくなり、歩留まりが著しく低下した。
【０２４７】
実施例４
セルロースエステルに変えて、ノルボルネン樹脂を用いて、下記組成のドープを調製した以外は実施例１と同様にして溶液流延法によりノルボルネン樹脂フィルムを作製した。フィルムの作製において、幅手方向の伸縮率Ａ、搬送方向の伸縮率Ｂ、その比（Ａ／Ｂ）が表４に記載の値となるように、各搬送張力条件、剥離時の残留溶媒量、テンターでの延伸条件、乾燥温度及び膜厚を適宜調整した。
【０２４８】
《ノルボルネン樹脂溶液（ドープ）》
ノルボルネン樹脂（アートンＧ、ジェイエスアール社製）　　１００質量部
メチレンクロライド　　　　　　　　　　　　　　　　　　　２３３質量部
得られたノルボルネン樹脂フィルムを実施例１と同様にして、リターデーション値Ｒｏ、遅相軸角度θの測定及び寸法安定性の評価を行った。その結果を表４に示す。
【０２４９】
【表４】

【０２５０】
得られたノルボルネン樹脂フィルムに実施例１と同様にしてクリアハードコート層を設け、その上に酸化錫層を形成して光学フィルム１９〜２５を得た。この光学フィルムについて実施例１と同様にして端部のクラックや、筋ムラを評価した。その結果を表５に示す。
【０２５１】
【表５】

【０２５２】
本発明の光学フィルムでは幅１ｍ越えるフィルムでも端部でのクラックや筋ムラが認められなかったのに対して、比較のフィルムではクラックや筋ムラのため、歩留まりが著しく低下した。
【０２５３】
【発明の効果】
本発明により、筋ムラ及びクラックが少ない光学フィルム及びその製造方法、これを用いた偏光板及び表示装置を提供することができる。
【図面の簡単な説明】
【図１】溶液流延製膜長尺樹脂フィルム製造装置の一例を示す概略図である。
【図２】テンター乾燥装置を有する溶液流延製膜長尺樹脂フィルム製造装置の一例を示す概略図である。
【図３】
本発明の金属酸化物薄膜層を形成するのに用いられるプラズマＣＶＤ処理装置の一例を示す図である。
【図４】本発明の金属酸化物薄膜層を形成するのに有用な回転電極と固定電極を有するプラズマＣＶＤ処理装置の一例を示す図である。
【符号の説明】
Ｆ　フィルム（ウェブともいう）
Ｐ　長尺樹脂フィルム
Ｇ　反応ガス
Ｇ′　排ガス
１　金属支持体
２　ダイ
３、４　乾燥工程
５　剥離ロール
６、９　ロール乾燥装置
７　巻取り部
８　テンター乾燥装置
６１　乾燥ガス風
６３　ロール
７２　巻取り機
１１０Ａ、１１０Ｂ、１１０　回転電極
１１１Ａ、１１１Ｂ、１１１Ｃ、１１１Ｄ　Ｕターンロール
１２０、１２１　ガイドロール
１３０　反応ガス供給部
１４０、２４０　ガス排気口
１５０、２５０　放電部
１８０、２８０　電源
１８２、２８１　電圧供給手段
２１０　回転電極
２１１　固定電極
２２０、２２１　ガイドロール
２２２、２２３　ニップロール
２２４、２２５　仕切板
２３０　給気管
２３１　反応ガス発生装置
２９０　プラズマＣＶＤ処理容器[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing an optical film, an optical film, a polarizing plate having the optical film, and a display device.
[0002]
[Prior art]
Liquid crystal display devices (LCDs) are widely used as display devices for word processors and personal computers because of their low voltage, low power consumption, direct connection to IC circuits, and thinness. ing.
[0003]
In order to provide higher visibility with higher definition and larger screen of a display device, an optical film having antireflection property or conductivity is required. The antireflection layer is formed by providing a plurality of layers having different refractive indexes, and a metal oxide layer is preferably used. Conventionally, it was provided by a method such as vapor deposition or sputtering, but there was a problem that the cost was high. On the other hand, recently, a method of forming by coating has been proposed, and an antireflection layer can be provided at lower cost. However, it has been difficult to uniformly provide a thin antireflection layer having a thickness of 0.1 μm or less. In addition, there is a problem that cracks occur during storage of a long resin film provided with a thin film, and improvement thereof has been demanded. In particular, cracks are likely to occur in the metal oxide layer having a metal oxide content of 70% by mass or more, and streak-like unevenness frequently occurs at the width end of the metal oxide layer. .
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide an optical film with less stripe unevenness and cracks, a method for manufacturing the same, a polarizing plate and a display device using the same.
[0005]
[Means for Solving the Problems]
The above object of the present invention has been achieved by the following configurations.
[0006]
1. The resin solution was cast on a metal support by a solution casting film forming method, and the peeled film was dried while gripping both ends of the width and regulating the width dimensions. In the process during which the film is dried until it is not more than mass% and wound up, the expansion and contraction ratio A in the width direction represented by the above formula (1) and the expansion and contraction ratio B in the transport direction represented by the above formula (2) are obtained. To produce a long resin film such that the ratio (A / B) is 2.0 to 10.0 and the expansion / contraction ratio B is -0.5% or less. A method for producing an optical film, comprising forming a metal oxide layer via a coating layer.
[0007]
2. 2. The method for producing an optical film as described in 1 above, wherein the amount of the residual solvent when peeled from the metal support is 20 to 150% by mass.
[0008]
3. 3. The method for producing an optical film according to 1 or 2, wherein A / B is 2.5 to 8.0.
[0009]
4. The method for producing an optical film according to any one of the above items 1 to 3, wherein the metal oxide layer is formed by plasma CVD.
[0010]
5. The method for producing an optical film according to any one of the above items 1 to 4, wherein the metal oxide layer is formed by applying a composition containing a metal oxide.
[0011]
6. 6. The method for producing an optical film according to any one of the above items 1 to 5, wherein the resin solution contains a cellulose ester or a norbornene resin.
[0012]
7. An optical film produced by the method according to any one of the above items 1 to 6.
[0013]
8. When the angle between the longitudinal direction of the long resin film and the in-plane slow axis direction is θ, the absolute value of θ is less than 5 °, and the in-plane retardation value Ro is 0.5 to 7 nm. An optical film having a metal oxide layer directly on a long resin film or via another coating layer.
[0014]
9. 9. The optical film according to the above item 8, wherein the absolute value of θ is less than 1 °.
[0015]
10. 10. The optical film according to any one of the above items 7 to 9, wherein the resin is a cellulose ester or a norbornene resin.
[0016]
11. The optical film according to any one of the above items 7 to 10, wherein the long resin film has a thickness of 10 to 70 µm.
[0017]
12. A polarizing plate comprising the optical film according to any one of the above items 7 to 11 on at least one surface.
[0018]
13. A display device comprising the optical film according to any one of the above items 7 to 11.
[0019]
Hereinafter, details of the present invention will be described.
The present inventor has conducted repeated studies to solve the above problem, and as a result, the absolute value of the slow axis angle of the resin film provided with the metal oxide layer with respect to the longitudinal direction is less than 5 °, and the in-plane retardation value. It has been found that remarkably improved by setting Ro to 0.5 to 7 nm. The absolute value of the slow axis angle is preferably less than 2 °, particularly preferably less than 1 °.
[0020]
Especially when the thickness of the base film was thin and cracks were easily generated during storage as a long film, the present invention was applied when a long film having a thickness of 10 to 70 μm was used. Also, the occurrence of cracks was significantly reduced. In addition, streak-like unevenness was also reduced at the width end.
[0021]
There is no particular limitation on the method for setting the in-plane slow axis angle θ and the in-plane retardation value Ro in the width to a predetermined range, but when forming a long film by a solution casting method or the like, the resin solution is used. The film cast and peeled on a metal support is dried while holding the both ends of the width and regulating the width dimensions, and further dried until the residual solvent amount of the film becomes 1% by mass or less, and wound up. In the process during which the ratio (A / B) of the expansion / contraction ratio A in the width direction represented by the above formula (1) to the expansion / contraction ratio B in the transport direction represented by the above formula (2) is 2.0. It is preferable to set the expansion / contraction ratio B to -0.5% or less. Forming a metal oxide layer on the long film directly or via another coating layer is a method for producing an optical film of the present invention.
[0022]
Here, the film width on the metal support when calculating the expansion / contraction A means not the actual casting width but the width when the wound film width portion is in contact with the metal support. That is, in the actual film forming process, the edge is removed by slitting. For example, in FIG. 2, since a slitter is provided before and after the tenter drying device 8 and an end is cut off, the actual casting width is different. Therefore, in order to obtain the expansion / contraction ratio A, the film on the metal support is marked at a fixed interval in the width direction, for example, 1 m, and this is designated as A1, and the interval in the width direction of the marking at the time of winding is A2. Then, the expansion ratio A can be obtained as A = (A2 / A1-1) × 100 (%).
[0023]
The optical film having the metal oxide layer produced in this manner was hardly cracked, and the streak-like unevenness was reduced at the width end. In the long resin film produced by this method, the absolute value of the slow axis angle θ with respect to the longitudinal direction can be less than 5 °, and the in-plane retardation value Ro can be 0.5 to 7 nm. At this time, it is preferable that A / B is 2.5 to 8.0. Preferably, the amount of residual solvent when peeled off from the metal support is 20 to 150% by mass. When it is within this range, cracks are more difficult to be formed.
[0024]
Here, the slow axis refers to the x-axis which is the main axis of the refractive index ellipsoid in the optical film, and the angle between the slow axis and the transport direction (longitudinal direction) during film formation is called the slow axis angle θ. .
[0025]
The long resin film according to the present invention specifically refers to a film having a length of about 100 to 5000 m, and is usually provided in a roll form. Although there was a problem that cracks easily occurred during storage as a long resin film when the thickness of the base film was thin, according to the present invention, a thin long resin film having a thickness of 10 to 70 μm was used. Even in this case, the occurrence of cracks in the metal oxide layer was significantly reduced. In addition, the streak-like film thickness unevenness of the metal oxide layer at the width end was reduced.
[0026]
The absolute value of the in-plane slow axis angle is more preferably less than 1 °, and the occurrence of cracks is further suppressed.
[0027]
The method for providing the metal oxide layer on the long resin film is not particularly limited, but is preferably formed by plasma CVD or coating. In particular, it is preferably formed by plasma CVD. According to the present invention, cracks can be significantly reduced even in a metal oxide layer having a metal oxide content of 70% by mass or more. In particular, cracks were likely to occur near both ends of the long resin film having a width exceeding 1 m, but the occurrence of cracks in this portion can be sufficiently suppressed. In addition, streak-like unevenness that was likely to occur at the width end was also significantly reduced. This makes it possible to provide an antireflection film excellent in yield even for a large display device having a size exceeding 20 inches.
[0028]
In addition, in the case of the conductive film, the conductivity did not decrease even when stored in a roll film, and stable conductivity was obtained especially at the end portion, and the yield was remarkably improved.
[0029]
The method for producing a long resin film of the present invention will be described. The resin constituting the long resin film is not particularly limited, but is preferably a cellulose ester or a norbornene resin. Cellulose triacetate is preferably used as the cellulose ester. The norbornene-based resin is a polymer of a monomer having a norbornene structure, and among them, an amorphous polyolefin having a norbornene structure is preferable. Specific examples of the norbornene-based resin composition include “APO” manufactured by Mitsui Petrochemical Co., Ltd., “ZEOX” manufactured by Zeon Corporation, and “ARTON” manufactured by JSR Corporation.
[0030]
Hereinafter, a method for manufacturing a long resin film using a cellulose ester will be described. However, a similar method can be used when a norbornene-based resin is used.
[0031]
As an example of a method for producing a long resin film by a solution casting method, a method for producing a cellulose ester film as shown in FIG. 1 is used. FIG. 1 is a schematic view showing an example of an apparatus for producing a long resin film by solution casting. In FIG. 1, a cellulose ester solution is dissolved in a mixed solvent of a good solvent that dissolves a cellulose ester and a poor solvent that does not dissolve, and various additives such as a plasticizer and an ultraviolet absorber are added to the solution as needed. In the following, the dope is prepared, and the dope is provided with a mirror-finished surface, and has an infinitely moving endless metal support 1 (for example, a metal support or simply a support in a belt or drum shape). A film F (also referred to as a web or a dope film) is formed by casting from a die 2 and air with adjusted temperature and humidity is blown from drying steps 3 and 4 provided above and below the metal support 1, After cooling and constant drying, the film F is peeled off by the peeling roll 5, transferred by the roll 63, introduced into the roll drying device 6, and drawn around the roll F by the roll 63. The film F therebetween as cellulose ester film is dried by the drying gas air 61 introduced, is manufactured is wound by winder 72 of the winding unit 7. A belt is particularly preferably used as the metal support.
[0032]
Usually, in the drying step, a film as shown in FIG. 1 is generally passed through a large number of rolls 63 in a zigzag manner, and a drying air is applied. However, as shown in U.S. Pat. No. 2,319,053, an infrared ray is used. There is also a method of drying with the like. In addition, a so-called air loop method has been developed in which a film is not directly wound on a roll, but is blown out by air and the film is floated by the wind pressure to move the film in a non-contact state with a suspended body (for example, a special air loop method). No. 55-135046, etc.).
[0033]
Further, in the drying step, it is preferable to hold the both ends using a tenter device or the like and to dry while regulating the width. FIG. 2 shows an example of an apparatus for producing a long casting resin film for solution casting having the above tenter drying apparatus.
[0034]
In the same manner as in the method described in FIG. 1 described above, the film F peeled off by the peeling roll 5 is introduced into a tenter drying device 8 and both ends of the film are held with clips to maintain the width, or the width is slightly stretched. Go and dry. After the drying is completed, a rolled long resin film is obtained.
[0035]
When a long resin film is manufactured by the above-described method, there are some problems. That is, after peeling the dope cast on the metal support, by stretching in the width direction with a tenter, the flatness is improved, while the slow axis angle is large at the end in the width direction. Become.
[0036]
In addition, the polyvinyl alcohol film used for the polarizing plate has high water absorption, shrinks greatly when left under high humidity, and failures such as peeling of the laminated film if the mechanical strength of the protective film laminated on both sides is weak. May cause.
[0037]
Furthermore, since liquid crystal display devices can be made thinner and smaller, their application to notebook personal computers, car navigators, mobile phones, game consoles, etc. is proceeding at a very rapid pace. It is becoming. Accordingly, there has been a demand for further development of a thin film for a long resin film of a liquid crystal image display device conventionally used. In the case of such a thin film, the use of a tenter to improve the flatness tends to increase the slow axis angle. In addition, in the case of a thin film, the strength of the film is weakened, and the force of suppressing the shrinkage of the polyvinyl alcohol film due to moisture absorption is further weakened.
[0038]
In the method for producing a long resin film used in the present invention, the production steps mainly include a step of casting a dope on a metal support as shown in FIG. 1 and FIG. , A peeling step of peeling the film from the metal support, and a step of drying the film.
[0039]
In the metal support used in the present invention, it is preferable that the surface of the endless metal support for infinite transfer is a mirror surface. In the casting step, the dope is fed to a pressurized die through a pressurized metering gear pump, and at the casting position, the dope is cast from the pressurized die onto a metal support, for example, a stainless steel belt or a rotating metal drum. It is. Other methods of casting include, for example, a doctor blade method of adjusting the film thickness of the cast dope film with a blade, and a method of using a reverse roll coater to adjust the film with a counter-rotating roll. From the viewpoint that the slit shape can be adjusted and the film thickness can be easily made uniform, it is preferable to use a pressure die. Examples of the pressure die include a coat hanger die and a T die, and any of them is preferably used. Further, in order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the doping amount may be divided to form a multilayer film. Adjustment of the film thickness is performed by appropriately adjusting the dope concentration, the liquid feed amount of the pump, the slit gap of the die cap, the extrusion pressure of the die, the speed of the metal support, etc. so that the desired thickness is obtained. be able to.
[0040]
The drying step on the metal support is a step of heating a web (the web is referred to as a dope film after casting on the metal support) on the metal support to evaporate the solvent. To evaporate the solvent, for example, a method in which heated air is blown from the web side and the back side of the metal support, a method in which heat is transferred from the back side of the metal support by a heating liquid, a method in which heat is transferred from the front and back sides by radiant heat, and the like. Can be. Further, a method of appropriately selecting and combining them is also preferable. In addition, if the thickness of the web is thin, drying is quick. The temperature of the metal support may be the same as a whole or different depending on the position.
[0041]
The peeling step is a step of evaporating the organic solvent on the metal support and peeling the web before the metal support goes around, and then the film is sent to a drying step. The position at which the web is peeled off from the metal support is referred to as a peeling point, and the roll which assists peeling is referred to as a peeling roll. Although it depends on the thickness of the web, if the residual solvent amount of the web at the peeling point (the following formula) is too large, it is difficult to peel off, or conversely, if the web is sufficiently dried on a metal support and then peeled off, Some parts of the web may peel off.
[0042]
Although it depends on the type of the resin, it is preferable that the web is peeled off when the amount of the residual solvent measured by the method described later is 20 to 150% by mass. When the peeling is performed at less than 20% by mass, when the tension in the transport direction is increased for the purpose of increasing the mechanical strength of the long resin film, residual stress is generated in the long resin film, and the dimensional stability is deteriorated. . On the other hand, if it exceeds 150% by mass, peeling residue is generated, which is not preferable because it causes surface defects of the long resin film.
[0043]
Further, as one of the methods capable of increasing the film forming speed by peeling while the residual solvent amount is as large as possible, there is a gel casting method capable of peeling even if the residual solvent amount is large. . The gel casting method includes a method in which a poor solvent for the cellulose ester is added to the dope to form a gel after casting the dope, or a method in which the temperature of the metal support is lowered to form a gel. There is also a method of adding a metal salt to the dope. By gelling on the metal support and strengthening the doped film, peeling can be accelerated and the film forming speed can be increased. If the film is peeled at a point where the residual solvent amount is larger, if the film is too soft, the flatness at the time of peeling will be impaired, or shear or vertical stripes will easily occur due to peeling tension, and the residual solvent amount will be determined in consideration of economic speed and quality Can be
[0044]
The residual solvent amount used in the present invention can be represented by the following equation.
Residual solvent amount (% by mass) = {(M−N) / N} × 100
Here, M is the mass of the film at an arbitrary point in time, and N is the mass when the M is dried at 110 ° C. for 3 hours.
[0045]
In the film drying step, it is preferable to further dry the film peeled from the metal support and reduce the amount of the residual solvent to 1% by mass or less in order to obtain a film having good dimensional stability. It is particularly preferable that the residual solvent amount at the time of winding is 0.00 to 0.10% by mass. Further, it is preferable that there is no unevenness in the residual solvent amount in the width direction. In the film drying step, generally, a method of drying while transporting a film by a roll suspension method, a pin tenter method, or a clip tenter method is employed. In the present invention, the ratio (A / B) of the expansion / contraction ratio A in the width direction represented by the above formula (1) to the expansion / contraction ratio B in the transport direction represented by the above formula (2) is 2.0 to 10%. It is preferable to dry while stretching in the width direction by a tenter method so that the expansion and contraction ratio B is -0.5% or less, in order to improve dimensional stability.
[0046]
In particular, in the present invention, it is preferable to carry out width holding or stretching where the amount of the residual solvent immediately after peeling from the metal support is large, since the effect of improving the dimensional stability is further exhibited.
[0047]
In the drying step after peeling from the metal support, the film tends to shrink in the width direction due to evaporation of the solvent. Furthermore, the shrinkage increases as the temperature increases. Drying while suppressing this shrinkage as much as possible is preferable for improving the flatness and dimensional stability of the resulting film. From this point, for example, a method of drying all the steps or a part of the steps as described in JP-A-62-46625 while holding both ends of the film widthwise with clips in the width direction, that is, a so-called tenter method is used. Preferably, it is used.
[0048]
In the present invention, the means for drying the film is not particularly limited, and for example, can be performed using hot air, infrared rays, a heating roll, a microwave, or the like, and from the viewpoint of simplicity, a method using hot air is preferable. . It is preferable that the drying temperature is divided into three to five stages within a temperature range of 40 to 150 ° C., and the drying temperature is gradually increased. It is preferable to realize the property.
[0049]
Each step from the casting to the post-drying may be performed under an air atmosphere or under an inert gas atmosphere such as nitrogen gas. In addition, it is needless to say that the drying atmosphere is performed in consideration of the explosive limit concentration of the solvent.
[0050]
The winding machine according to the present invention for producing a long resin film may be a commonly used one, for example, a constant tension method, a constant torque method, a taper tension method, a program tension control method with a constant internal stress, and the like. Can be wound up.
[0051]
In the present invention, the film is dried until the residual solvent amount of the film becomes 1% by mass or less after peeling, and in a process during winding, the stretching ratio A in the width direction represented by the formula (1) and The tenter is set so that the ratio (A / B) to the expansion and contraction ratio B in the transport direction represented by the formula (2) is 2.0 to 10.0 and the expansion and contraction ratio B is -0.5% or less. It is characterized by drying while stretching in the width direction by the method.
[0052]
The expansion / contraction rate A in the width direction is obtained from the transport speed (m / min) of the metal support forming the film shown in FIGS. 1 and 2 and the transport speed of the winder 72 of the winding unit 7. Can be. If A / B deviates from 2.0 to 10.0, the effect of the present invention is not recognized, and if it exceeds 10.0, cracks worsen.
[0053]
In the present invention, there is no particular limitation on a method for optimally adjusting the transport device of the metal support or the winding section so as to be in the range of A / B defined above, but the drying conditions and transport tension in each step are not particularly limited. It is most effective to appropriately adjust the conditions and the like.
[0054]
Next, details of the long resin film of the present invention will be described below.
Cellulose ester used in the long resin film of the present invention is obtained by reacting acetic anhydride, propionic anhydride, or butyric anhydride by a conventional method using cellulose selected from linter pulp, wood pulp and kenaf pulp. Preferably, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, and cellulose acetate propionate butyrate having a degree of substitution of all acyl groups with respect to hydroxyl groups of cellulose of 2.5 to 3.0 are used.
[0055]
The substitution degree of the acetyl group of the cellulose ester according to the present invention is preferably at least 1.5 or more. For example, cellulose acetate propionate having an acetyl group substitution degree of 2.0 and a propionyl group substitution degree of 0.8 is preferably used. The method for measuring the degree of substitution of the acyl group of the cellulose ester can be carried out according to ASTM D-817-91. The molecular weight of these cellulose esters is preferably in the range of 70,000 to 300,000 as the number average molecular weight, because the mechanical strength when formed into a film is strong, and more preferably 80,000 to 200,000. Usually, the cellulose ester is in the form of flakes after treatment such as washing with water after the reaction, and is used in that shape.As the particle size, it is more preferable that the average particle size is in the range of 0.05 to 2.0 mm. It is preferable from the viewpoint of accelerating the solubility.
[0056]
The long resin film contains a plasticizer such as phthalic acid ester and phosphate ester, an ultraviolet absorber, an antioxidant, a matting agent, etc., so that the performance of the liquid crystal image display device caused by the long resin film is obtained. Can be improved, which is preferable.
[0057]
In the present invention, the plasticizer that can be contained in the long resin film is not particularly limited. Examples of the phosphoric acid ester type include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, and octyl diphenyl. Phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc., as phthalic acid esters, such as diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, glycolic acid ester, etc. Are triacetin, tributyrin, butylphthalylbutyl glycolate, ethylphthalylethyl glycolate, methylphthalylethyl glycolate, It can be exemplified Le phthalyl butyl glycolate and the like. In addition, dicyclohexyl phthalate, dibenzyl phthalate, trimethylolpropane tribenzoate and the like are preferably used. If necessary, two or more plasticizers may be used in combination.
[0058]
When used in the long resin film of the present invention, the use ratio of the phosphate ester-based plasticizer is preferably 50% by mass or less because hydrolysis of the long resin film hardly occurs and the durability is excellent. It is more preferable that the ratio of the phosphate ester plasticizer is small, and it is particularly preferable to use only a non-phosphate ester plasticizer such as a phthalate ester or a glycolate ester. The amount of the plasticizer added to the cellulose ester is preferably 0.5 to 30% by mass, and particularly preferably 2 to 15% by mass.
[0059]
Further, in the present invention, from the viewpoint of preventing the deterioration of the liquid crystal, the ultraviolet absorber which can be contained in the long resin film is excellent in the ability to absorb ultraviolet light having a wavelength of 370 nm or less and has a good liquid crystal display property. Those that absorb as little as possible visible light having a wavelength of 400 nm or more are preferably used. In particular, the transmittance at a wavelength of 370 nm needs to be 10% or less, preferably 5% or less, more preferably 2% or less. In the present invention, examples of the ultraviolet absorber that can be used include oxybenzophenone-based compounds, benzotriazole-based compounds, salicylate-based compounds, benzophenone-based compounds, triazine-based compounds, cyanoacrylate-based compounds, nickel complex-based compounds, and the like. However, a less colored benzotriazole-based compound is preferable. As a commercially available benzotriazole-based ultraviolet absorber, for example, Tinuvin 109, Tinuvin 171, Tinuvin 326, Tinuvin 327, Tinuvin 328, and the like manufactured by Ciba Specialty Chemicals can be preferably used, but not limited thereto. Two or more ultraviolet absorbers may be used.
[0060]
As a method of adding the ultraviolet absorber to the dope, the ultraviolet absorber may be added after dissolving the ultraviolet absorber in an organic solvent such as alcohol, methylene chloride, methyl acetate, or dioxolane, or may be directly added to the dope composition. Those that do not dissolve in an organic solvent, such as inorganic powders, are dispersed in an organic solvent and a cellulose ester using a dissolver or a sand mill, and then added to the dope. In the present invention, the amount of the ultraviolet absorber used can be added in the range of 0.5 to 20% by mass relative to the cellulose ester, preferably 0.6 to 5.0% by mass, particularly preferably 0.6 to 5.0% by mass. 2.0% by mass.
[0061]
In the present invention, the long resin film preferably contains a fine particle matting agent. Examples of the fine particle matting agent include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, It is preferable to include inorganic fine particles such as talc, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate, and crosslinked polymer fine particles. Among them, silicon dioxide is preferable because the haze (devitrification) of the film can be reduced. The secondary particles of the fine particles preferably have an average particle size of 0.01 to 1.0 μm, and the content thereof is preferably 0.005 to 0.5% by mass based on the cellulose ester. Fine particles such as silicon dioxide are often surface-treated with an organic substance, but such particles are preferable because the haze of the film can be reduced. Preferred organic substances for the surface treatment include, for example, halosilanes, alkoxysilanes, silazane, siloxane and the like. As the average particle size of the fine particles, the larger the larger, the greater the matting effect, and the smaller the average particle size, the better the transparency. Therefore, the average primary particle size of the fine particles is preferably 5 to 50 nm, more preferably 7 to 50 nm. ２０20 nm. These fine particles are usually present as an aggregate in the long resin film, and it is preferable to form irregularities of 0.01 to 1.0 μm on the surface of the long resin film. Examples of the fine particles of silicon dioxide include AEROSIL 200, 200V, 300, R972, R972V, R974, R202, R812, OX50, and TT600 manufactured by Nippon Aerosil Co., Ltd., and preferably AEROSIL 200V, R972, and the like. R972V, R974, R202, and R812. Two or more of these matting agents may be used in combination. When two or more kinds are used in combination, they can be used by mixing at an arbitrary ratio. In this case, a matting agent having a different average particle size or a different material, for example, AEROSIL 200V and R972V may be used in a mass ratio of 0.1: 99.9 to 99.9: 0.1.
[0062]
Next, a method for preparing a cellulose ester dope in the present invention will be described. While stirring an organic solvent mainly composed of a good solvent for cellulose ester in a dissolving vessel, a flake-shaped cellulose ester is added and dissolved to form a dope. As the dissolution method, for example, a method at normal pressure, a method at a temperature lower than the boiling point of the main solvent, a method at a pressure higher than the boiling point of the main solvent, JP-A-9-95544 and JP-A-9-95557 Alternatively, various dissolving methods such as a method performed by a cooling dissolution method described in JP-A-9-95538 and a method performed at a high pressure as described in JP-A-11-21379 can be exemplified. The dissolved cellulose ester solution, so-called dope, is then filtered by a filter medium, defoamed, and sent to the next step by a pump. The concentration of the cellulose ester in the dope is generally 10 to 35% by mass, preferably 15 to 25% by mass. In order to incorporate the polymer useful in the present invention into the cellulose ester dope, the polymer may be dissolved in an organic solvent in advance and then added, or the polymer may be directly added to the cellulose ester dope. In this case, it is necessary to add the polymer with care so that the polymer does not become cloudy or phase-separated in the dope.
[0063]
The good solvent that can be used in the present invention is an organic solvent having good solubility in cellulose ester, for example, methyl acetate, ethyl acetate, amyl acetate, ethyl formate, acetone, cyclohexanone, methyl acetoacetate, Tetrahydrofuran, 1,3-dioxolan, 4-methyl-1,3-dioxolan, 1,4-dioxane, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1 , 3-Difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, 2-pyrrolidone, N-methyl-2-pyrrolidone, , 3-dimethyl-2-imidazolidinone, there may be mentioned methylene chloride, bromo propane, in particular, methyl acetate, acetone, are preferably used methylene chloride. However, it is preferable to use a non-chlorine organic solvent in view of recent environmental problems. Further, it is preferable to use a lower alcohol such as methanol, ethanol, or butanol in combination with these organic solvents, because the solubility of the cellulose ester in the organic solvent can be improved and the viscosity of the dope can be reduced. In particular, ethanol having a low boiling point and low toxicity is preferred. The organic solvent used in the dope according to the present invention is preferably used from the viewpoint of production efficiency by mixing a good solvent and a poor solvent for the cellulose ester, and a preferable range of the mixing ratio of the good solvent and the poor solvent is a good solvent. Is 70 to 98% by mass, and the poor solvent is 2 to 30% by mass. For example, a mixed solvent of 70% by mass of methyl acetate and 30% by mass of ethanol is mentioned as an example of a preferable solvent. The good solvent and the poor solvent used in the present invention are defined as a good solvent that dissolves the cellulose ester used alone and a poor solvent that does not dissolve the cellulose ester alone. The poor solvent used in the dope according to the present invention is not particularly limited. For example, methanol, ethanol, n-butanol, cyclohexane, acetone, cyclohexanone, and the like can be preferably used. For the polymer useful in the present invention, it is preferable to select an organic solvent using a good solvent for the cellulose ester. As described above, when a low-molecular plasticizer is used, it can be performed by a usual addition method, even if it is directly added to the dope, or it is dissolved in an organic solvent and then poured into the dope. Good.
[0064]
In the present invention, when the various additive solutions or dispersions as described above are added to the cellulose ester dope, they are transferred from the respective transfer series, and when the transfer pipes are joined, the respective addition elements are combined as a dope solution, Immediately thereafter, a method of sufficiently mixing with a mixer in a tube is also preferable. For example, it is preferable to use an inline mixer such as a static mixer SWJ (Toray static type in-pipe mixer Hi-Mixer manufactured by Toray Engineering). When an in-line mixer is used, a cellulose ester can be applied to a dope in which the cellulose ester is concentrated and dissolved under high pressure.
[0065]
In the present invention, in the preparation of the cellulose ester dope, it is necessary to remove foreign matter, particularly foreign matter that is easily recognized as an image in a liquid crystal image display device. When the long resin film of the present invention is used as a protective film for a polarizing plate, it is no exaggeration to say that the quality is determined by the filtration accuracy. It is preferable that the filtration media used for filtration have a small absolute filtration accuracy.However, if the absolute filtration accuracy is too small, clogging of the filtration media is likely to occur, and frequent replacement of the filtration media is required. There is a problem to make it. For this reason, the filter medium used for the cellulose ester dope according to the present invention preferably has an absolute filtration accuracy of 0.008 mm or less, more preferably 0.001 to 0.008 mm, and more preferably 0.003 to 0.006 mm. Is more preferable. There is no particular limitation on the material of the filter medium, and a normal filter medium can be used. However, a filter medium made of a plastic fiber such as polypropylene or Teflon (R) or a metal filter medium such as a stainless steel fiber may cause the fiber to fall off. Preferred. Filtration of the cellulose ester dope according to the present invention can be performed by a normal method, but a method of filtering while heating under pressure at a temperature not lower than the boiling point of the solvent at normal pressure and a range in which the solvent does not boil, filtration is The rise in differential pressure before and after the material (hereinafter sometimes referred to as filtration pressure) is small, which is preferable. A preferred temperature range is 45 to 120 ° C, more preferably 45 to 70 ° C, and even more preferably 45 to 55 ° C. The smaller the filtration pressure, the better. Filtration pressure is 1.6 × 10 ⁶ Pa or less, preferably 1.2 × 10 ⁶ Pa or less, more preferably 1.0 × 10 ⁶ More preferably, it is Pa or less.
[0066]
Further, when the cellulose ester of the raw material contains a cellulose ester having an unsubstituted or low-substituted acyl group, a foreign substance failure (hereinafter also referred to as a bright spot failure) may occur. The bright spot failure means that when a long resin film is placed between two polarizing plates in a crossed state (crossed Nicols), light is irradiated from one side, and observed with an optical microscope (50 ×) from the other side. In the case of a long resin film, the light is blocked and nothing looks black. However, if there is a foreign substance, the light leaks from it and appears as a spot-like light, which is recognized as a foreign substance. The larger the diameter of the bright spot failure, the greater the effect of the liquid crystal image display device, and it is preferable that there is substantially no device having a diameter of 50 μm or more. It is preferable that the bright spot failure of 50 μm or less is as small as possible, and that the diameter thereof is also small. Preferably 10/50 μm 200 / cm ² The following is preferable, and the smaller the value, the better. The diameter of a bright point means a diameter measured by approximating the bright point to a perfect circle. In order to reduce the number and magnitude of such bright spot failures, it is necessary to sufficiently filter fine foreign matter. Further, as described in JP-A-2000-137115, a method in which a pulverized product of a long resin film formed once is re-added to a dope at a certain ratio and used as a raw material for a cellulose ester and its additive, Is a preferred method that can reduce the
[0067]
As the thickness of the long resin film, generally, a thickness of 10 to 200 μm is used. However, in order to reduce the thickness and weight of a polarizing plate used for an LCD or the like, the thickness is 10 to 70 μm in the present invention. Is more preferably, 20 to 60 μm, further preferably 35 to 50 μm. If the thickness is less than 10 μm, the stiffness of the film is reduced, so that it is easy to cause troubles such as wrinkles in the production process of the polarizing plate, which is not preferable. Further, when a thin long resin film having a thickness of 70 μm or less was used, cracks and uneven stripes in the metal oxide layer were likely to occur, but the present invention has improved this point.
[0068]
In the long resin film of the present invention, it is preferable that the slow axis angle is less than 5 ° and the in-plane retardation value Ro is 0.5 to 7 nm.
[0069]
The slow axis angle in the present invention is an angle (degree) between a film transport direction and a slow axis direction during film formation, and an in-plane retardation value Ro (nm) is represented by the following equation. .
[0070]
Ro = (Nx−Ny) × d
Nx: refractive index in the maximum refractive index direction (slow axis direction) in the plane of the film
Ny: refractive index in the direction in the film plane orthogonal to the slow axis (fast axis direction)
d: film thickness (nm)
In the present invention, the refractive index of the entire long resin film can be measured using an ellipsometer or the like. Further, using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Scientific Instruments), the birefringence index was measured at a wavelength of 590 nm under an environment of 23 ° C. and 55% RH to obtain Nx-Ny. The Ro value and the slow axis angle can be calculated by measuring the thickness of the film.
[0071]
Next, an antireflection film which is one of the optical films of the present invention will be described. In the antireflection film of the present invention, the metal oxide layer may be directly formed on the long resin film described above, but at least one other coating layer is provided and formed on the long resin film having an uneven surface. You may let it. As the other coating layer, a cured resin layer having a center line average surface roughness (Ra) of 0.01 to 1 μm specified in JIS B 0601 is preferable. These are preferably actinic ray-curable resin layers that are cured by actinic rays such as ultraviolet rays. By forming the metal oxide layer according to the present invention on such a resin layer cured by ultraviolet rays, an antireflection film having excellent scratch resistance can be obtained.
[0072]
The metal oxide layer is preferably used for at least one of a high refractive index layer, a medium refractive index layer, and a low refractive index layer.
[0073]
In the present invention, the method for forming the metal oxide layer is not particularly limited, and the metal oxide layer can be formed by coating, CVD, sputtering, or vapor deposition, but is preferably formed by plasma CVD even during coating or CVD.
[0074]
A method for forming a metal oxide layer by coating will be described.
The basic structure of the antireflection film of the present invention will be described. For example, a preferable antireflection film has a layer structure in the order of a transparent support, a hard coat layer, a medium refractive index layer, a high refractive index layer, and a low refractive index layer. The transparent support, the middle refractive index layer, the high refractive index layer and the low refractive index layer have a refractive index satisfying the following relationship.
[0075]
Refractive index of low refractive index layer <refractive index of transparent support <refractive index of medium refractive index layer <refractive index of high refractive index layer
In an antireflection film having a middle refractive index layer, a high refractive index layer, and a low refractive index layer, as described in JP-A-59-50401, the medium refractive index layer satisfies the following formula (1). When the refractive index layer satisfies the following mathematical formula (2) and the low refractive index layer satisfies the following mathematical formula (3), it is possible to further reduce the average reflectance as an antireflection film, which is preferable.
[0076]
(Hλ / 4) × 0.7 <n ₃ d ₃ <(Hλ / 4) × 1.3 Expression (1)
In the formula (1), h is a positive integer (generally 1, 2 or 3), and n ₃ Is the refractive index of the middle refractive index layer, and d ₃ Is the thickness (nm) of the middle refractive index layer. Λ is a wavelength and is a value in the range of 350 to 800 (nm).
[0077]
(Jλ / 4) × 0.7 <n ₄ d ₄ <(Jλ / 4) × 1.3 Expression (2)
In the formula (2), j is a positive integer (generally 1, 2 or 3), and n ₄ Is the refractive index of the high refractive index layer and d ₄ Is the thickness (nm) of the high refractive index layer. Λ is a wavelength and is a value in the range of 350 to 800 (nm).
[0078]
(Kλ / 4) × 0.7 <n ₅ d ₅ <(Kλ / 4) × 1.3 Expression (3)
In equation (3), k is a positive odd number (generally 1) and n ₅ Is the refractive index of the low refractive index layer and d ₅ Is the thickness (nm) of the low refractive index layer. Λ is a wavelength and is a value in the range of 350 to 800 (nm).
[0079]
Further, in the present invention, it is also preferable to provide irregularities on the hard coat layer or the high refractive index layer to form an antiglare antireflection film.
[0080]
In addition, a layer configuration in the order of the transparent support, the hard coat layer (anti-glare layer), the high refractive index layer, the low refractive index layer, the high refractive index layer, and the low refractive index layer is also a preferable configuration. It is preferable to impart antifouling properties to the low refractive index layer on the surface, and an antifouling layer may be provided on the surface.
[0081]
<High refractive index layer and medium refractive index>
In the present invention, in order to reduce the reflectance, it is preferable to provide a high refractive index layer between the transparent support or the transparent support provided with the hard coat layer and the low refractive index layer. It is preferable to provide a middle refractive index layer between the transparent support and the high refractive index layer in order to reduce the reflectance. The refractive index of the high refractive index layer is preferably from 1.55 to 2.30, and more preferably from 1.57 to 2.20. The refractive index of the middle refractive index layer is adjusted to be an intermediate value between the refractive index of the transparent support and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably from 1.55 to 1.80. The thickness of the high refractive index layer and the middle refractive index layer is preferably from 5 nm to 1 μm, more preferably from 10 nm to 0.2 μm, and most preferably from 30 nm to 0.1 μm. The haze of the high refractive index layer and the middle refractive index layer is preferably 5% or less, more preferably 3% or less, and most preferably 1% or less. The strength of the high refractive index layer and the medium refractive index layer is preferably H or more, more preferably 2H or more, and most preferably 3H or more at a pencil hardness of 1 kg load. The high refractive index layer and the medium refractive index layer preferably contain inorganic fine particles and a binder polymer.
[0082]
The inorganic fine particles used for the high refractive index layer and the medium refractive index layer preferably have a refractive index of 1.80 to 2.80, and more preferably 1.90 to 2.80. The weight average diameter of the primary particles of the inorganic fine particles is preferably from 1 to 150 nm, more preferably from 1 to 100 nm, and most preferably from 1 to 80 nm. The weight average diameter of the inorganic fine particles in the layer is preferably 1 to 200 nm, more preferably 5 to 150 nm, further preferably 10 to 100 nm, and most preferably 10 to 80 nm. . The average particle diameter of the inorganic fine particles is measured by a light scattering method when it is 20 to 30 nm or more, and by an electron micrograph when it is 20 to 30 nm or less. The specific surface area of the inorganic fine particles is 10 to 400 m as a value measured by the BET method. ² / G, preferably 20 to 200 m ² / G, more preferably 30 to 150 m ² / G is most preferred.
[0083]
The inorganic fine particles are preferably particles formed from a metal oxide or sulfide. Examples of metal oxides or sulfides include titanium dioxide (eg, rutile, a mixed crystal of rutile / anatase, anatase, amorphous structure), tin oxide, indium oxide, zinc oxide, zirconium oxide, and zinc sulfide. Among them, titanium oxide, tin oxide and indium oxide are particularly preferred. The inorganic fine particles contain oxides or sulfides of these metals as main components and may further contain other elements. The main component means a component having the largest content (% by mass) of the components constituting the particles. Examples of other elements include Ti, Zr, Sn, Sb, Cu, Fe, Mn, Pb, Cd, As, Cr, Hg, Zn, Al, Mg, Si, P and S.
[0084]
The inorganic fine particles may be surface-treated. The surface treatment can be performed using an inorganic compound or an organic compound. Examples of the inorganic compound used for the surface treatment include alumina, silica, zirconium oxide, and iron oxide. Of these, alumina and silica are preferred. Examples of organic compounds used for the surface treatment include polyols, alkanolamines, stearic acid, silane coupling agents, and titanate coupling agents. Among them, a silane coupling agent is most preferable. The surface treatment may be performed by combining two or more types of surface treatments. The shape of the inorganic fine particles is preferably a rice grain, a sphere, a cube, a spindle, or an irregular shape. Two or more kinds of inorganic fine particles may be used in combination with the high refractive index layer and the medium refractive index layer.
[0085]
The ratio of the inorganic fine particles in the high refractive index layer and the medium refractive index layer is preferably from 5 to 65% by volume, more preferably from 10 to 60% by volume, and still more preferably from 20 to 55% by volume.
[0086]
The inorganic fine particles are provided in the form of a dispersion dispersed in a medium to a coating liquid for forming a high refractive index layer and a medium refractive index layer. As a dispersion medium of the inorganic fine particles, it is preferable to use a liquid having a boiling point of 60 to 170 ° C. Specific examples of the dispersion solvent include water, alcohol (eg, methanol, ethanol, isopropanol, butanol, benzyl alcohol), ketone (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone), ester (eg, methyl acetate, ethyl acetate) , Propyl acetate, butyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate), aliphatic hydrocarbons (eg, hexane, cyclohexane), halogenated hydrocarbons (eg, methylene chloride, chloroform, carbon tetrachloride), aroma Group hydrocarbons (eg, benzene, toluene, xylene), amides (eg, dimethylformamide, dimethylacetamide, n-methylpyrrolidone), ethers (eg, diethyl ether, dioxane, tetrahydrofuran), ether alcohols (eg, 1-methoxy-2-propanol). Among them, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and butanol are particularly preferred.
[0087]
The inorganic fine particles can be dispersed in the medium using a disperser. Examples of the disperser include a sand grinder mill (eg, a bead mill with pins), a high-speed impeller mill, a pebble mill, a roller mill, an attritor, and a colloid mill. Sand grinder mills and high speed impeller mills are particularly preferred. Further, a preliminary dispersion process may be performed. Examples of the disperser used for the preliminary dispersion treatment include a ball mill, a three-roll mill, a kneader, and an extruder.
[0088]
The high refractive index layer and the middle refractive index layer preferably use a polymer having a crosslinked structure (hereinafter, also referred to as a crosslinked polymer) as a binder polymer. Examples of the crosslinked polymer include crosslinked products of polymers having a saturated hydrocarbon chain such as polyolefin (hereinafter collectively referred to as polyolefin), polyether, polyurea, polyurethane, polyester, polyamine, polyamide and melamine resin. Of these, a crosslinked product of polyolefin, polyether and polyurethane is preferred, a crosslinked product of polyolefin and polyether is more preferred, and a crosslinked product of polyolefin is most preferred. Further, it is more preferable that the crosslinked polymer has an anionic group. The anionic group has a function of maintaining the dispersed state of the inorganic fine particles, and the crosslinked structure has a function of imparting a film-forming ability to the polymer to strengthen the film. The anionic group may be directly bonded to the polymer chain, or may be bonded to the polymer chain via a linking group, but is bonded to the main chain as a side chain via the linking group. Is preferred.
[0089]
Examples of the anionic group include a carboxylic acid group (carboxyl), a sulfonic acid group (sulfo) and a phosphoric acid group (phosphono). Among them, a sulfonic acid group and a phosphoric acid group are preferable. Here, the anionic group may be in a salt state. The cation forming a salt with the anionic group is preferably an alkali metal ion. Further, the proton of the anionic group may be dissociated. The linking group that bonds the anionic group and the polymer chain is preferably a divalent group selected from —CO—, —O—, an alkylene group, an arylene group, and a combination thereof. The crosslinked polymer which is a preferred binder polymer is preferably a copolymer having a repeating unit having an anionic group and a repeating unit having a crosslinked structure. In this case, the proportion of the repeating unit having an anionic group in the copolymer is preferably from 2 to 96% by mass, more preferably from 4 to 94% by mass, and most preferably from 6 to 92% by mass. preferable. The repeating unit may have two or more anionic groups.
[0090]
The crosslinked polymer having an anionic group may contain another repeating unit (a repeating unit having neither an anionic group nor a crosslinked structure). As other repeating units, a repeating unit having an amino group or a quaternary ammonium group and a repeating unit having a benzene ring are preferable. The amino group or the quaternary ammonium group has a function of maintaining the dispersed state of the inorganic fine particles, similarly to the anionic group. The benzene ring has a function of increasing the refractive index of the high refractive index layer. The same effect can be obtained even when the amino group, the quaternary ammonium group and the benzene ring are contained in the repeating unit having an anionic group or the repeating unit having a crosslinked structure.
[0091]
In the crosslinked polymer containing a repeating unit having an amino group or a quaternary ammonium group as a constituent unit, the amino group or the quaternary ammonium group may be directly bonded to a polymer chain, or may be a side chain via a linking group. May be bonded to the polymer chain, but the latter is more preferred. The amino group or the quaternary ammonium group is preferably a secondary amino group, a tertiary amino group or a quaternary ammonium group, and more preferably a tertiary amino group or a quaternary ammonium group. The group bonded to the nitrogen atom of the secondary amino group, tertiary amino group or quaternary ammonium group is preferably an alkyl group, more preferably an alkyl group having 1 to 12 carbon atoms, and further preferably an alkyl group having 1 to 12 carbon atoms. 1 to 6 alkyl groups. The counter ion of the quaternary ammonium group is preferably a halide ion. The linking group that bonds the amino group or the quaternary ammonium group to the polymer chain is a divalent group selected from -CO-, -NH-, -O-, an alkylene group, an arylene group, and a combination thereof. Is preferred. When the crosslinked polymer contains a repeating unit having an amino group or a quaternary ammonium group, the proportion is preferably from 0.06 to 32% by mass, more preferably from 0.08 to 30% by mass, Most preferably, it is 0.1 to 28% by mass.
[0092]
A crosslinked polymer is prepared by blending a monomer for generating a crosslinked polymer to prepare a coating liquid for forming a high refractive index layer and a medium refractive index layer, and by performing a polymerization reaction simultaneously with or after the application of the coating liquid. Is preferred. Each layer is formed with the formation of the crosslinked polymer. The monomer having an anionic group functions as a dispersant for inorganic fine particles in the coating solution. The monomer having an anionic group is preferably used in an amount of 1 to 50% by mass, more preferably 5 to 40% by mass, and still more preferably 10 to 30% by mass, based on the inorganic fine particles. The monomer having an amino group or a quaternary ammonium group functions as a dispersing aid in the coating solution. The monomer having an amino group or a quaternary ammonium group is preferably used in an amount of 3 to 33% by mass based on the monomer having an anionic group. A method of producing a crosslinked polymer by a polymerization reaction at the same time as or after the application of the coating liquid allows these monomers to function effectively before the application of the coating liquid.
[0093]
Examples of monomers having two or more ethylenically unsaturated groups include esters of polyhydric alcohol and (meth) acrylic acid (eg, ethylene glycol di (meth) acrylate, 1,4-dichlorohexane diacrylate, pentane). Erythritol tetra (meth) acrylate), pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethanetri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) Acrylate, pentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate, vinylbenzene and derivatives thereof ( , 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinylsulfone (eg, divinylsulfone), acrylamide (eg, methylenebisacrylamide), methacrylamide, and the like. No. As the monomer having an anionic group and the monomer having an amino group or a quaternary ammonium group, commercially available monomers may be used. Preferable commercially available monomers having an anionic group include KAYAMARPM-21, PM-2 (manufactured by Nippon Kayaku Co., Ltd.), AntoxMS-60, MS-2N, and MS-NH4 (manufactured by Nippon Emulsifier Co., Ltd.) Aronix M-5000, M-6000, M-8000 series (manufactured by Toagosei Chemical Industry Co., Ltd.), VISCOAT # 2000 series (manufactured by Osaka Organic Chemical Industry Co., Ltd.), New Frontier GX-8289 (Daiichi Kogyo Pharmaceutical Co., Ltd.) NK Ester CB-1, A-SA (manufactured by Shin-Nakamura Chemical Co., Ltd.), AR-100, MR-100, MR-200 (manufactured by Daihachi Chemical Industry Co., Ltd.) and the like. Can be Further, preferably used commercially available monomers having an amino group or a quaternary ammonium group include DMAA (manufactured by Osaka Organic Chemical Industry Co., Ltd.), DMAEA, DMAPAA (manufactured by Kojin Co., Ltd.), and Blemmer QA (manufactured by NOF Corporation. )), New Frontier C-1615 (Daiichi Kogyo Seiyaku Co., Ltd.) and the like.
[0094]
As the polymerization reaction of the polymer, a photopolymerization reaction or a thermal polymerization reaction can be used. Particularly, a photopolymerization reaction is preferable. It is preferable to use a polymerization initiator for the polymerization reaction. For example, the above-mentioned thermal polymerization initiator and photopolymerization initiator used for forming the binder polymer of the hard coat layer can be used.
[0095]
A commercially available polymerization initiator may be used as the polymerization initiator. A polymerization accelerator may be used in addition to the polymerization initiator. The addition amount of the polymerization initiator and the polymerization accelerator is preferably in the range of 0.2 to 10% by mass of the total amount of the monomers. The coating liquid (dispersion of inorganic fine particles containing a monomer) may be heated to promote polymerization of the monomer (or oligomer). Further, heating may be performed after the photopolymerization reaction after the application, and the thermosetting reaction of the formed polymer may be additionally treated.
[0096]
It is preferable to use a polymer having a relatively high refractive index for the middle refractive index layer and the high refractive index layer. Examples of polymers having a high refractive index include polystyrene, styrene copolymer, polycarbonate, melamine resin, phenolic resin, epoxy resin, and polyurethane obtained by reacting a cyclic (alicyclic or aromatic) isocyanate with a polyol. . Other polymers having a cyclic (aromatic, heterocyclic, alicyclic) group or polymers having a halogen atom other than fluorine as a substituent can also be used with a high refractive index.
[0097]
The metal oxide layer is preferably provided by applying a coating solution containing inorganic fine particles containing a metal oxide.
[0098]
A high refractive index layer or a medium refractive index layer may be formed from an organometallic compound having a film forming ability.
[0099]
Preferably, the organometallic compound can be dispersed in a suitable medium or is in a liquid state. Examples of the organometallic compound include metal alcoholates (eg, titanium tetraethoxide, titanium tetra-i-propoxide, titanium tetra-n-propoxide, titanium tetra-n-butoxide, titanium tetra-sec-butoxide, titanium Tetra-tert-butoxide, aluminum triethoxide, aluminum tri-i-propoxide, aluminum tributoxide, antimony triethoxide, antimony tributoxide, zirconium tetraethoxide, zirconium tetra-i-propoxide, zirconium tetra-n- Propoxide, zirconium tetra-n-butoxide, zirconium tetra-sec-butoxide, zirconium tetra-tert-butoxide, chelating compounds (eg, di-isopropoxytitanium bi Acetylacetonate, di-butoxytitanium bisacetylacetonate, di-ethoxytitanium bisacetylacetonate, bisacetylacetone zirconium, aluminum acetylacetonate, aluminum di-n-butoxide monoethylacetoacetate, aluminum di-i-propoxide monomethyl Acetoacetate, tri-n-butoxide zirconium monoethyl acetoacetate), organic acid salts (eg, zirconyl ammonium carbonate), zirconium, and the like.
[0100]
The low-refractive-index layer includes a low-refractive-index layer formed by crosslinking a fluorine-containing resin that is crosslinked by heat or ionizing radiation (hereinafter also referred to as “fluorinated resin before crosslinking”), a low-refractive-index layer formed by a sol-gel method, and particles. And a binder polymer, and a low refractive index layer or the like having a void between particles or inside the particles is used. It is preferable that the refractive index of the low refractive index layer is low, because the antireflection performance is improved, but it is difficult from the viewpoint of imparting strength to the low refractive index layer. From this balance, the refractive index of the low refractive index layer is preferably from 1.30 to 1.50, and more preferably from 1.35 to 1.49.
[0101]
As the fluorine-containing resin before crosslinking, a fluorine-containing copolymer formed from a fluorine-containing vinyl monomer and a monomer for providing a crosslinking group can be preferably exemplified. Specific examples of the fluorine-containing vinyl monomer unit include, for example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3 -Dioxole, etc.), partially or fully fluorinated alkyl ester derivatives of (meth) acrylic acid (for example, Biscoat 6FM (manufactured by Osaka Organic Chemicals) and M-2020 (manufactured by Daikin)), fully or partially fluorinated vinyl ethers, etc. Is mentioned. Examples of the monomer for providing a crosslinkable group include glycidyl methacrylate, vinyl trimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, vinyl glycidyl ether, and other vinyl monomers having a crosslinkable functional group in the molecule in advance. , A vinyl monomer having a carboxyl group, a hydroxyl group, an amino group, a sulfonic acid group, etc. (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, hydroxyalkyl vinyl ether, hydroxyalkylallyl Ether and the like). JP-A-10-25388 and JP-A-10-147739 disclose that the latter can introduce a crosslinked structure by adding a compound having a group that reacts with a functional group in the polymer and at least one more reactive group after copolymerization. No. Examples of the crosslinkable group include acryloyl, methacryloyl, isocyanate, epoxy, aziridine, oxazoline, aldehyde, carbonyl, hydrazine, carboxyl, methylol, active methylene group and the like. When the fluorinated copolymer is crosslinked by heating, due to a crosslinkable group that reacts by heating, or a combination of an ethylenically unsaturated group and a thermal radical generator or an epoxy group and a thermal acid generator, a thermosetting type When cross-linking by irradiation of light (preferably ultraviolet light, electron beam, or the like) with a combination of an ethylenically unsaturated group and a photo radical generator or an epoxy group and a photo acid generator, it is an ionizing radiation-curable type. .
[0102]
Further, in addition to the above monomers, a fluorine-containing copolymer formed by using a fluorine-containing vinyl monomer and a monomer other than a monomer for providing a crosslinkable group in combination may be used as a fluorine-containing resin before crosslinking. There are no particular limitations on the monomers that can be used in combination, and for example, olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylates (methyl acrylate, methyl acrylate, ethyl acrylate, acrylic acid 2- Ethylhexyl), methacrylates (methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene, vinyltoluene, α-methylstyrene, etc.), vinyl ethers (methyl vinyl ether) ), Vinyl esters (vinyl acetate, vinyl propionate, vinyl cinnamate, etc.), acrylamides (N-tertbutylacrylamide, N-cyclohexylacrylamide, etc.), methacrylamides, Ronitoriru derivatives and the like can be mentioned. It is also preferable to introduce a polyorganosiloxane skeleton or a perfluoropolyether skeleton into the fluorinated copolymer for imparting slipperiness and antifouling property. This includes, for example, polymerization of a polyorganosiloxane or perfluoropolyether having an acrylic group, a methacryl group, a vinyl ether group, a styryl group or the like at the terminal with the above-mentioned monomer, or a polyorganosiloxane or perfluoropolyether having a radical generating group at the terminal. It can be obtained by polymerization of the above monomers with ether, reaction of a polyorganosiloxane or perfluoropolyether having a functional group with a fluorinated copolymer, or the like.
[0103]
The proportion of each of the above monomers used to form the fluorine-containing copolymer before crosslinking is preferably such that the fluorine-containing vinyl monomer is 20 to 70 mol%, more preferably 40 to 70 mol%, The amount of the monomer is preferably 1 to 20 mol%, more preferably 5 to 20 mol%, and the other monomer used in combination is preferably 10 to 70 mol%, more preferably 10 to 50 mol%.
[0104]
The fluorinated copolymer can be obtained by polymerizing these monomers in the presence of a radical polymerization initiator by means such as solution polymerization, bulk polymerization, emulsion polymerization, and suspension polymerization.
[0105]
The fluorine-containing resin before crosslinking is commercially available and can be used. Examples of commercially available fluororesins before crosslinking include Cytop (manufactured by Asahi Glass), Teflon (R) AF (manufactured by Dupont), polyvinylidene fluoride, Lumiflon (manufactured by Asahi Glass), Opstar (manufactured by JSR), and the like. Can be
[0106]
The low refractive index layer containing a crosslinked fluorine-containing resin as a component preferably has a dynamic friction coefficient in a range of 0.03 to 0.15 and a contact angle with water in a range of 90 to 120 degrees.
[0107]
It is preferable that the low refractive index layer containing a crosslinked fluorine-containing resin as a component contains inorganic particles from the viewpoint of improving strength. As the inorganic fine particles used for the low refractive index layer, an amorphous fine particle is preferably used, and is preferably formed of a metal oxide, nitride, sulfide or halide, and among them, metal oxide is particularly preferable. As metal atoms, Na, K, Mg, Ca, Ba, Al, Zn, Fe, Cu, Ti, Sn, In, W, Y, Sb, Mn, Ga, V, Nb, Ta, Ag, Si, B , Bi, Mo, Ce, Cd, Be, Pb and Ni are preferred, and Mg, Ca, B and Si are more preferred. Inorganic fine particles containing two or more metals may be used. Particularly preferred inorganic fine particles are silicon dioxide fine particles, that is, silica fine particles. The average particle diameter of the inorganic fine particles is preferably from 0.001 to 0.2 μm, more preferably from 0.005 to 0.05 μm. It is preferable that the particle size of the fine particles is as uniform (monodispersed) as possible. If the particle size of the inorganic fine particles is too large, light is scattered, and the film becomes opaque. If the particle size is too small, the particles are easily aggregated and the synthesis and handling are difficult.
[0108]
The compounding amount of the inorganic fine particles is preferably 5 to 90% by mass, more preferably 10 to 70% by mass, and particularly preferably 10 to 50% by mass based on the total mass of the low refractive index layer. The inorganic fine particles are also preferably subjected to a surface treatment before use. As the surface treatment method, there are a physical surface treatment such as a plasma discharge treatment or a corona discharge treatment and a chemical surface treatment using a coupling agent, but the use of a coupling agent is preferable. As the coupling agent, an organoalkoxy metal compound (eg, a titanium coupling agent, a silane coupling agent, etc.) is preferably used. When the inorganic fine particles are silica, treatment with a silane coupling agent is particularly effective.
[0109]
Various sol-gel materials can also be used as the material for the low refractive index layer. As such a sol-gel material, metal alcoholates (alcoholates such as silane, titanium, aluminum and zirconium), organoalkoxy metal compounds and hydrolysates thereof can be used. In particular, alkoxysilanes, organoalkoxysilanes and hydrolysates thereof are preferred. Examples of these include tetraalkoxysilanes (tetramethoxysilane, tetraethoxysilane, etc.), alkyltrialkoxysilanes (methyltrimethoxysilane, ethyltrimethoxysilane, etc.), aryltrialkoxysilanes (phenyltrimethoxysilane, etc.), dialkyl Dialkoxysilane, diaryldialkoxysilane, and the like. Also, organoalkoxysilanes having various functional groups (vinyl trialkoxysilane, methylvinyldialkoxysilane, γ-glycidyloxypropyl trialkoxysilane, γ-glycidyloxypropylmethyldialkoxysilane, β- (3,4-epoxy) Dicyclohexyl) ethyl trialkoxysilane, γ-methacryloyloxypropyl trialkoxysilane, γ-aminopropyl trialkoxysilane, γ-mercaptopropyl trialkoxysilane, γ-chloropropyl trialkoxysilane, etc.), perfluoroalkyl group-containing silane compound ( For example, it is also preferable to use (heptadecafluoro-1,1,2,2-tetradecyl) triethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, or the like. In particular, the use of a fluorine-containing silane compound is preferable in terms of lowering the refractive index of the layer and imparting water / oil repellency.
[0110]
It is also preferable to use inorganic or organic fine particles as the low refractive index layer, and to use a layer formed as microvoids between fine particles or within fine particles. The average particle size of the fine particles is preferably 0.5 to 200 nm, more preferably 1 to 100 nm, further preferably 3 to 70 nm, and most preferably 5 to 40 nm. The particle diameter of the fine particles is preferably as uniform (monodispersed) as possible.
[0111]
The inorganic fine particles are preferably amorphous. The inorganic fine particles are preferably made of metal oxide, nitride, sulfide or halide, more preferably made of metal oxide or metal halide, most preferably made of metal oxide or metal fluoride. . As metal atoms, Na, K, Mg, Ca, Ba, Al, Zn, Fe, Cu, Ti, Sn, In, W, Y, Sb, Mn, Ga, V, Nb, Ta, Ag, Si, B , Bi, Mo, Ce, Cd, Be, Pb and Ni are preferred, and Mg, Ca, B and Si are more preferred. An inorganic compound containing two kinds of metals may be used. A particularly preferred inorganic compound is silicon dioxide, ie, silica.
[0112]
The microvoids in the inorganic fine particles can be formed, for example, by crosslinking silica molecules forming the particles. Crosslinking silica molecules reduces the volume and makes the particles porous. The (porous) inorganic fine particles having microvoids can be obtained by a sol-gel method (described in JP-A-53-112732 and JP-B-57-9051) or a precipitation method (described in APPLIED OPTICS, vol. 27, p. 3356 (1988)). Can be directly synthesized as a dispersion. Further, the powder obtained by the drying / precipitation method can be mechanically pulverized to obtain a dispersion. Commercially available porous inorganic fine particles (for example, silicon dioxide sol) may be used. The inorganic fine particles having microvoids are preferably used in a state of being dispersed in an appropriate medium in order to form a low refractive index layer. As the dispersion medium, water, alcohol (eg, methanol, ethanol, isopropyl alcohol) and ketone (eg, methyl ethyl ketone, methyl isobutyl ketone) are preferable.
[0113]
Preferably, the organic fine particles are also amorphous. The organic fine particles are preferably polymer fine particles synthesized by a polymerization reaction of a monomer (for example, an emulsion polymerization method). The polymer of the organic fine particles preferably contains a fluorine atom. The proportion of fluorine atoms in the polymer is preferably from 35 to 80% by mass, more preferably from 45 to 75% by mass. It is also preferable to form microvoids in the organic fine particles by, for example, crosslinking the polymer forming the particles and reducing the volume. In order to crosslink the polymer forming the particles, it is preferable that 20 mol% or more of the monomer for synthesizing the polymer is a polyfunctional monomer. The proportion of the polyfunctional monomer is more preferably from 30 to 80 mol%, most preferably from 35 to 50 mol%. Examples of the monomer used for synthesizing the organic fine particles include fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene) as examples of a monomer containing a fluorine atom used for synthesizing a fluoropolymer. , Perfluoro-2,2-dimethyl-1,3-dioxole), fluorinated alkyl esters of acrylic acid or methacrylic acid and fluorinated vinyl ethers. A copolymer of a monomer containing a fluorine atom and a monomer containing no fluorine atom may be used. Examples of monomers containing no fluorine atom include olefins (eg, ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride), acrylates (eg, methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate) , Methacrylates (eg, methyl methacrylate, ethyl methacrylate, butyl methacrylate), styrenes (eg, styrene, vinyltoluene, α-methylstyrene), vinyl ethers (eg, methyl vinyl ether), vinyl esters ( Examples include vinyl acetate, vinyl propionate), acrylamides (eg, N-tert-butylacrylamide, N-cyclohexylacrylamide), methacrylamides, and acrylonitriles. Examples of polyfunctional monomers include dienes (eg, butadiene, pentadiene), esters of polyhydric alcohol and acrylic acid (eg, ethylene glycol diacrylate, 1,4-cyclohexane diacrylate, dipentaerythritol hexaacrylate), Esters of polyhydric alcohol and methacrylic acid (eg, ethylene glycol dimethacrylate, 1,2,4-cyclohexanetetramethacrylate, pentaerythritol tetramethacrylate), divinyl compounds (eg, divinylcyclohexane, 1,4-divinylbenzene), divinyl Sulfones, bisacrylamides (eg, methylenebisacrylamide) and bismethacrylamides.
[0114]
Microvoids between particles can be formed by stacking at least two or more fine particles. When spherical particles having the same particle size (completely monodispersed) are closest packed, microvoids between particles having a porosity of 26% by volume are formed. When spherical particles having the same particle size are simply cubic-filled, microvoids between particles having a porosity of 48% by volume are formed. In an actual low refractive index layer, the porosity considerably fluctuates from the above theoretical value due to the distribution of the particle size of the fine particles and the presence of microvoids in the particles. Increasing the porosity lowers the refractive index of the low refractive index layer. By forming microvoids by stacking fine particles and adjusting the particle size of the fine particles, the size of the microvoids between particles can be easily set to an appropriate value (does not scatter light and does not cause a problem in the strength of the low refractive index layer). Can be adjusted. Further, by making the particle diameter of the fine particles uniform, an optically uniform low refractive index layer in which the size of microvoids between particles is also uniform can be obtained. Thus, the low refractive index layer can be a microvoid-containing porous film microscopically, but can be an optically or macroscopically uniform film. It is preferable that the interparticle microvoids are closed in the low refractive index layer by the fine particles and the polymer. The closed void also has the advantage that light is less scattered on the surface of the low-refractive-index layer compared to an opening opened on the surface of the low-refractive-index layer.
[0115]
By forming microvoids, the macroscopic refractive index of the low refractive index layer becomes a value lower than the sum of the refractive indices of the components constituting the low refractive index layer. The refractive index of a layer is the sum of the refractive indices per volume of the components of the layer. The refractive index of a component of the low refractive index layer such as a fine particle or a polymer is a value larger than 1, while the refractive index of air is 1.00. Therefore, a low refractive index layer having a very low refractive index can be obtained by forming microvoids.
[0116]
The low refractive index layer preferably contains the polymer in an amount of 5 to 50% by weight. The polymer has a function of adhering the fine particles and maintaining the structure of the low refractive index layer including voids. The amount of the polymer used is adjusted so that the strength of the low refractive index layer can be maintained without filling the void. The amount of the polymer is preferably 10 to 30% by mass of the total amount of the low refractive index layer. In order to adhere the fine particles with the polymer, (1) bonding the polymer to the surface treatment agent of the fine particles, (2) forming a polymer shell around the fine particles as a core, or (3) forming a polymer shell around the fine particles. It is preferable to use a polymer as the binder. The polymer to be bound to the surface treatment agent (1) is preferably the shell polymer (2) or the binder polymer (3). It is preferable that the polymer (2) is formed around the fine particles by a polymerization reaction before preparing the coating liquid for the low refractive index layer. The polymer of (3) is preferably formed by adding a monomer to the coating solution for the low refractive index layer and performing a polymerization reaction simultaneously with or after the coating of the low refractive index layer. It is preferable to carry out a combination of two or all of the above (1) to (3), and to carry out a combination of (1) and (3) or a combination of all (1) to (3). Particularly preferred. (1) Surface treatment, (2) Shell and (3) Binder will be described sequentially.
[0117]
(1) Surface treatment
The fine particles (particularly, inorganic fine particles) are preferably subjected to a surface treatment to improve the affinity with the polymer. The surface treatment can be classified into a physical surface treatment such as a plasma discharge treatment and a corona discharge treatment, and a chemical surface treatment using a coupling agent. It is preferable to carry out only a chemical surface treatment or a combination of a physical surface treatment and a chemical surface treatment. As the coupling agent, an organoalkoxy metal compound (eg, a titanium coupling agent, a silane coupling agent) is preferably used. When the fine particles are made of silicon dioxide, surface treatment with a silane coupling agent can be particularly effectively performed. Specific examples of silane coupling agents include methyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxyethoxysilane, methyltriacetoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, and vinyltriethoxysilane. Methoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltriacetoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, γ-chloropropyltriacetoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-glycidyloxy Propyltriethoxysilane, γ- (β-glycidyloxyethoxy) propyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane, γ-acryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane and β-cyanoethyltriethoxysilane.
[0118]
Examples of silane coupling agents having a disubstituted alkyl group with respect to silicon include dimethyldimethoxysilane, phenylmethyldimethoxysilane, dimethyldiethoxysilane, phenylmethyldiethoxysilane, and γ-glycidyloxypropylmethyldiethoxysilane. Γ-glycidyloxypropylmethyldimethoxysilane, γ-glycidyloxypropylphenyldiethoxysilane, γ-chloropropylmethyldiethoxysilane, dimethyldiacetoxysilane, γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropylmethyldimethoxysilane Ethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropylmethyldiethoxysilane, γ-mercaptopropylmethyldimethyl Kishishiran, .gamma.-mercaptopropyl methyl diethoxy silane, .gamma.-aminopropyl methyl dimethoxy silane, .gamma.-aminopropyl methyl diethoxy silane, methyl vinyl dimethoxy silane, and methyl vinyl diethoxy silane.
[0119]
Among them, vinyltrimethoxysilane having a double bond in the molecule, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltrimethoxyethoxysilane, γ-acryloyloxypropyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane Γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropylmethyldiethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropylmethyldiethoxysilane as those having a disubstituted alkyl group to silicon Silane, methylvinyldimethoxysilane and methylvinyldiethoxysilane are preferred, and γ-acryloyloxypropyltrimethoxysilane and γ-methacryloyloxy Propyltrimethoxysilane, γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropylmethyldiethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane and γ-methacryloyloxypropylmethyldiethoxysilane are particularly preferred.
[0120]
Two or more coupling agents may be used in combination. Other silane coupling agents may be used in addition to the silane coupling agents shown above. Other silane coupling agents include alkyl esters of orthosilicic acid (e.g., methyl orthosilicate, ethyl orthosilicate, n-propyl orthosilicate, i-propyl orthosilicate, n-butyl orthosilicate, sec-butyl orthosilicate, ortho-silicate, T-butyl acid) and its hydrolyzate. The surface treatment with the coupling agent can be carried out by adding the coupling agent to the dispersion of fine particles and leaving the dispersion at a temperature from room temperature to 60 ° C. for several hours to 10 days. To promote the surface treatment reaction, inorganic acids (eg, sulfuric acid, hydrochloric acid, nitric acid, chromic acid, hypochlorous acid, boric acid, orthosilicic acid, phosphoric acid, carbonic acid), organic acids (eg, acetic acid, polyacrylic acid, Benzenesulfonic acid, phenol, polyglutamic acid), or salts thereof (eg, metal salts, ammonium salts) may be added to the dispersion.
[0121]
(2) Shell
The polymer forming the shell is preferably a polymer having a saturated hydrocarbon as a main chain. A polymer containing a fluorine atom in a main chain or a side chain is preferable, and a polymer containing a fluorine atom in a side chain is more preferable. Polyacrylates or polymethacrylates are preferred, and esters of fluorine-substituted alcohols with polyacrylic or polymethacrylic acid are most preferred. The refractive index of the shell polymer decreases as the content of fluorine atoms in the polymer increases. In order to lower the refractive index of the low refractive index layer, the shell polymer preferably contains 35 to 80% by mass of fluorine atoms, and more preferably 45 to 75% by mass. The polymer containing a fluorine atom is preferably synthesized by a polymerization reaction of an ethylenically unsaturated monomer containing a fluorine atom. Examples of ethylenically unsaturated monomers containing a fluorine atom include fluoroolefins (eg, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole), Esters of fluorinated vinyl ether and fluorine-substituted alcohol with acrylic acid or methacrylic acid.
[0122]
The polymer forming the shell may be a copolymer composed of a repeating unit containing a fluorine atom and a repeating unit containing no fluorine atom. The repeating unit containing no fluorine atom is preferably obtained by a polymerization reaction of an ethylenically unsaturated monomer containing no fluorine atom. Examples of the ethylenically unsaturated monomer containing no fluorine atom include olefins (eg, ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride), acrylates (eg, methyl acrylate, ethyl acrylate, acrylic acid 2- Ethylhexyl), methacrylates (eg, methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate), styrene and its derivatives (eg, styrene, divinylbenzene, vinyltoluene, α-methylstyrene), vinyl ether ( For example, methyl vinyl ether), vinyl ester (for example, vinyl acetate, vinyl propionate, vinyl cinnamate), acrylamide (for example, N-tertbutylacrylamide, N-cyclohexylacryl) Amides), methacrylamide and acrylonitrile.
[0123]
When the binder polymer of (3) described later is used in combination, a crosslinkable functional group may be introduced into the shell polymer, and the shell polymer and the binder polymer may be chemically bonded by crosslinking. The shell polymer may have crystallinity. When the glass transition temperature (Tg) of the shell polymer is higher than the temperature at the time of forming the low refractive index layer, it is easy to maintain microvoids in the low refractive index layer. However, when Tg is higher than the temperature at the time of forming the low refractive index layer, the fine particles may not be fused and the low refractive index layer may not be formed as a continuous layer (as a result, the strength may be reduced). In that case, it is desirable to use the binder polymer of (3) described later in combination and form the low refractive index layer as a continuous layer with the binder polymer. By forming a polymer shell around the fine particles, core-shell fine particles are obtained. The core made of inorganic fine particles preferably contains 5 to 90% by volume of core fine particles, and more preferably 15 to 80% by volume. Two or more types of core-shell fine particles may be used in combination. Further, inorganic fine particles having no shell and core-shell particles may be used in combination.
[0124]
(3) Binder
The binder polymer is preferably a polymer having a saturated hydrocarbon or polyether as a main chain, and more preferably a polymer having a saturated hydrocarbon as a main chain. The binder polymer is preferably crosslinked. The polymer having a saturated hydrocarbon as a main chain is preferably obtained by a polymerization reaction of an ethylenically unsaturated monomer. In order to obtain a crosslinked binder polymer, it is preferable to use a monomer having two or more ethylenically unsaturated groups. Examples of the monomer having two or more ethylenically unsaturated groups include esters of polyhydric alcohol and (meth) acrylic acid (for example, ethylene glycol di (meth) acrylate, 1,4-dichlorohexane diacrylate, pentaerythritol Tetra (meth) acrylate), pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethanetri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate Pentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate, vinylbenzene and derivatives thereof For example, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinylsulfone (eg, divinylsulfone), acrylamide (eg, methylenebisacrylamide) and methacrylamide. No. The polymer having a polyether as a main chain is preferably synthesized by a ring-opening polymerization reaction of a polyfunctional epoxy compound. Instead of or in addition to the monomer having two or more ethylenically unsaturated groups, a crosslinked structure may be introduced into the binder polymer by a reaction of a crosslinkable group. Examples of the crosslinkable functional group include an isocyanate group, an epoxy group, an aziridine group, an oxazoline group, an aldehyde group, a carbonyl group, a hydrazine group, a carboxyl group, a methylol group, and an active methylene group. Vinyl sulfonic acid, acid anhydride, cyanoacrylate derivative, melamine, etherified methylol, ester and urethane can also be used as monomers for introducing a crosslinked structure. A functional group that exhibits crosslinkability as a result of a decomposition reaction, such as a block isocyanate group, may be used. Further, the cross-linking group is not limited to the above-mentioned compound, but may be one which shows reactivity as a result of decomposition of the above-mentioned functional group. As the polymerization initiator used for the polymerization reaction and the crosslinking reaction of the binder polymer, a thermal polymerization initiator and a photopolymerization initiator are used, and the photopolymerization initiator is more preferable. Examples of photopolymerization initiators include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds , Fluoroamine compounds and aromatic sulfoniums. Examples of acetophenones include 2,2-diethoxyacetophenone, p-dimethylacetophenone, 1-hydroxydimethylphenylketone, 1-hydroxycyclohexylphenylketone, 2-methyl-4-methylthio-2-morpholinopropiophenone and -Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone. Examples of benzoins include benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether. Examples of benzophenones include benzophenone, 2,4-dichlorobenzophenone, 4,4-dichlorobenzophenone and p-chlorobenzophenone. Examples of phosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide.
[0125]
The binder polymer is preferably formed by adding a monomer to the coating solution for the low-refractive-index layer, and simultaneously or after the application of the low-refractive-index layer, by a polymerization reaction (and a crosslinking reaction if necessary). Even if a small amount of polymer (for example, polyvinyl alcohol, polyoxyethylene, polymethyl methacrylate, polymethyl acrylate, diacetyl cellulose, triacetyl cellulose, nitrocellulose, polyester, alkyd resin) is added to the coating solution for the low refractive index layer Good.
[0126]
Each layer of the antireflection film or its coating solution contains, in addition to the above-mentioned components (inorganic fine particles, polymer, dispersion medium, polymerization initiator, polymerization accelerator), a polymerization inhibitor, a leveling agent, a thickener, a coloring inhibitor, An ultraviolet absorber, a silane coupling agent, an antistatic agent and an adhesion-imparting agent may be added. Each layer of the antireflection film may be formed by application by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating method or an extrusion coating method (US Patent No. 2,681,294). Can be. Two or more layers may be applied simultaneously. The method of simultaneous coating is described in U.S. Pat. Nos. 2,761,791, 2,918,898, 3,508,947, 3,526,528 and Yuji Harazaki, Coating Engineering, page 253, Asakura Shoten (1973).
[0127]
Next, a method for forming a metal oxide layer by plasma CVD will be described with reference to FIGS.
[0128]
The plasma CVD (plasma discharge) treatment under atmospheric pressure or a pressure close to the atmospheric pressure as a method for forming a metal oxide layer of the present invention is preferably performed by using a plasma CVD treatment apparatus as described below.
[0129]
FIG. 3 is a diagram showing an example of a plasma CVD apparatus used for forming the metal oxide layer of the present invention.
[0130]
In FIG. 3, the apparatus has a pair of rotating electrodes 110A and 110B, and a power supply 180 capable of applying a voltage for generating a plasma discharge is connected to the rotating electrodes 110A and 110B by voltage supply means 182. Grounded.
[0131]
The rotating electrodes 110A and 110B transport the long resin film while being wound, and are preferably roll electrodes or belt-like electrodes. FIG. 3 shows a roll electrode.
[0132]
The gap (electrode gap) between these rotating electrodes is a place where discharge is performed, and is set to an interval at which the long resin film P can be transported. The gap between the electrodes becomes the discharge unit 150.
[0133]
The electrode gap is maintained at an atmospheric pressure or a pressure close to the atmospheric pressure. The reactive gas G is supplied from the reactive gas supply unit 130, and the surface of the long resin film P is subjected to plasma discharge processing.
[0134]
Here, the long resin film P unwound from the original roll or the long resin film P conveyed from the previous process is transported via the guide roll 120 while first contacting the rotating electrode 110A rotating in the transport direction. Then, the thin film is formed on the surface of the long resin film P by passing through the discharge part 150.
[0135]
The long resin film P once discharged from the discharge unit 150 is U-turned by the U-turn rolls 111A to 111D, and this time, the long resin film P is applied to the rotating electrode 110B rotating in the opposite direction to the rotating electrode 110A. The thin resin film P is transferred while being in contact therewith, passes through the discharge part 150 again, and is further subjected to plasma discharge treatment on the surface of the long resin film P on which the thin film has been formed, thereby forming a thin film. The U-turn is usually performed for about 0.1 second to 1 minute.
[0136]
The reaction gas G used for the treatment is discharged from the gas discharge port 140 as exhaust gas G 'after the reaction.
[0137]
In the figure, the thin film formed on the long resin film P is omitted. The long resin film P having a thin film formed on the surface is conveyed through a guide roller 121 in the direction of a next step or a take-up roll (not shown).
[0138]
Therefore, the long resin film P is reciprocated through the discharge unit 150 in a state of being in close contact with the rotating electrodes 110A and 110B, and is subjected to plasma discharge processing.
[0139]
Although not shown, devices such as the rotating electrodes 110A and 110B, the guide rolls 120 and 121, the U-turn rolls 111A to 111D, the reaction gas supply unit 130, and the gas outlet 140 are surrounded by a plasma discharge processing container. It is preferable that it is contained.
[0140]
Further, although not shown, a temperature control medium for controlling the temperature of the rotating electrodes 110A and 110B is circulated as necessary, and the surface temperature of each electrode is controlled to a predetermined value. . Further, if necessary, a plurality of plasma CVD apparatuses can be arranged in series to continuously form different films.
[0141]
FIG. 4 is a diagram showing an example of a plasma discharge processing apparatus having a rotating electrode and a fixed electrode useful for forming a metal oxide layer of the present invention.
[0142]
It has a rotating electrode 210 and a plurality of fixed electrodes 211 arranged opposite to the rotating electrode 210, and a long resin film P conveyed from an original winding roll or a previous process (not shown) passes through a guide roll 220 and a nip roll 222. The long resin film P is guided to the rotating electrode 210 and is transported in synchronism with the rotation of the rotating electrode 210 while being in contact with the rotating electrode 210, and generates a reactive gas to the discharge unit 250 under atmospheric pressure or a pressure close to the atmospheric pressure. The reaction gas G prepared by the apparatus 231 is supplied from the air supply pipe 230, and a thin film is formed on the long resin film surface facing the fixed electrode 211.
[0143]
A power supply 280 to which a voltage for generating plasma discharge can be applied is connected to the rotating electrode 210 and the fixed electrode by a voltage supply means 281, and is grounded by 282.
[0144]
Further, the rotating electrode 210, the fixed electrode 211, and the discharge unit 250 are covered with a plasma CVD processing container 290. The treated exhaust gas G 'is exhausted from a gas exhaust port 240 at the lower part of the processing chamber. Alternatively, air supply pipes 230 and gas outlets 240 may be provided alternately between the fixed electrodes 211.
[0145]
The long resin film P subjected to the plasma discharge treatment is conveyed to the next step or a winding roll (not shown) via the nip roll 223 and the guide roll 221.
[0146]
The long resin film P is provided with partition plates 224 and 225 from the outside at the nip rolls 222 and 223 at the entrance and exit of the plasma discharge processing container, and comes along with the long resin film P together with the nip roll 222 from the outside. It is preferable to shut off the air and prevent the reaction gas G or exhaust gas G 'from leaking to the outside at the outlet. Although not shown, the rotating electrode 210 and the fixed electrode 211 circulate a temperature-controlled medium for temperature adjustment as needed.
[0147]
As described above, in the present invention, it is preferable that the long resin film on which the thin film is formed is subjected to the plasma discharge treatment while being transferred on the rotating electrode.
[0148]
The surface where the rotating electrode is in contact with the long resin film is required to have high smoothness, and the surface roughness of the rotating electrode is 10 μm or less as the maximum surface roughness (Rmax) specified in JIS-B-0601. Preferably, it is 5 μm or less, more preferably 1 μm or less.
[0149]
The surface of the electrode used in the present invention is desirably coated with a solid dielectric, and particularly desirably, a conductive base material such as a metal is coated with a solid dielectric. Examples of the solid dielectric include plastics such as polytetrafluoroethylene and polyethylene terephthalate, glass, silicon dioxide, and aluminum oxide (Al ₂ O ₃ ), Zirconium oxide (ZrO) ₂ ), Titanium oxide (TiO) ₂ ), And double oxides such as barium titanate.
[0150]
It is particularly preferable to use a ceramic-coated dielectric material which is obtained by spraying ceramics and then sealing with an inorganic material. Here, examples of the conductive base material such as a metal include metals such as silver, platinum, stainless steel, aluminum, and iron, and stainless steel is preferable from the viewpoint of processing.
[0151]
As the lining material, silicate glass, borate glass, phosphate glass, germanate glass, tellurite glass, aluminate glass, vanadate glass and the like are preferably used. However, among these, borate glass is more preferably used because it is easy to process.
[0152]
In the present invention, the electrode can be heated or cooled as necessary from the back side (inside). When the electrode is a belt, it can be cooled by gas from the back surface, but in the case of a rotating electrode using a roll, it is possible to supply a medium inside and control the temperature of the electrode surface and the temperature of the long resin film. preferable.
[0153]
As the medium, an insulative material such as distilled water or oil, particularly silicone oil, is preferably used.
[0154]
The temperature of the long resin film at the time of the discharge treatment varies depending on the treatment conditions, but is preferably room temperature to 200 ° C or lower, more preferably room temperature to 120 ° C or lower, and further preferably 50 to 110 ° C.
[0155]
It is desirable to prevent temperature unevenness from occurring particularly in the width direction of the long resin film surface during the discharge treatment, preferably within ± 5 ° C, more preferably within ± 1 ° C, and particularly preferably. Is within ± 0.1 ° C.
[0156]
In the present invention, the electrode gap is determined in consideration of the thickness of the solid dielectric, applied voltage and frequency, the purpose of utilizing plasma, and the like. The shortest distance between the solid dielectric and the electrode when the solid dielectric is installed on one of the electrodes, and the distance between the solid dielectrics when the solid dielectric is installed on both of the electrodes is uniform in each case. From the viewpoint of generating discharge plasma, the thickness is preferably 0.5 to 20 mm, particularly preferably 1 ± 0.5 mm.
[0157]
In the present invention, the flow rate of the mixed gas generated by the gas generator is controlled to the discharge portion in the electrode gap, and is introduced into the plasma discharge portion from the reaction gas supply port. The concentration and flow rate of the reaction gas are appropriately adjusted, but it is preferable to supply the processing gas to the electrode gap at a speed sufficient for the transport speed of the long resin film. In the discharge unit, it is desirable to set the flow rate and discharge conditions so that most of the supplied reaction gas reacts and is used for forming a thin film. If the reaction gas contains particles, it may cause a foreign substance failure. Therefore, it is preferable to use a reaction gas from which particles have been removed in advance by filtration or the like. Further, it is preferable to supply the reaction gas while heating it at 20 to 200 ° C., preferably 50 to 150 ° C., and more preferably 70 to 120 ° C. because the physical properties of the formed film are improved.
[0158]
In order to prevent the atmosphere from entering the discharge portion and prevent the reaction gas from leaking out of the apparatus, it is preferable that the electrodes and the long resin film being transferred are entirely surrounded and shielded from the outside. It is preferable that the long resin film is introduced into the discharge portion in the plasma discharge device while preventing entrainment of air. In the present invention, it is particularly preferable that the pressure of the discharge unit is maintained at or near atmospheric pressure.
[0159]
The term "atmospheric pressure" means a pressure of 20 to 200 kPa, and preferably 93 to 110 kPa in order to preferably obtain the effects described in the present invention. It is preferable that the discharge part has a slightly positive pressure with respect to the atmospheric pressure outside the apparatus, and it is more preferable that the atmospheric pressure outside the plasma apparatus be +0.1 kPa to 5 kPa.
[0160]
In the plasma discharge processing apparatus useful in the present invention, it is preferable to connect one of the electrodes to a power supply to apply a voltage, and to ground the other electrode to the ground to generate a discharge plasma, in order to generate a stable plasma. .
[0161]
The value of the voltage applied to the electrodes from the high-frequency power supply used in the present invention is appropriately determined. For example, the voltage is about 0.5 to 10 kV, the applied frequency is adjusted to 1 kHz to 150 MHz, and the waveform is a pulse wave. Or a sine wave. In particular, it is preferable to obtain a discharge part (discharge space) having a frequency of more than 100 kHz and not more than 50 MHz, which is preferable.
[0162]
The discharge density in the discharge part is 5 to 1000 W · min / m ² And particularly preferably 50 to 500 W · min / m ² It is desirable that
[0163]
It is desirable that the plasma discharge processing unit is appropriately surrounded by a processing container made of Pyrex (R) glass or the like, and a metal made of metal can be used as long as insulation from the electrodes can be obtained. For example, a polyimide resin or the like may be attached to the inner surface of an aluminum or stainless steel frame, and the metal frame may be sprayed with ceramics to obtain insulation. Further, by surrounding the side surfaces of the discharge unit, the side surface of the rotating electrode, the long resin film transport unit, and the like, the reaction gas and the exhaust gas can be appropriately supplied to and discharged from the discharge unit.
[0164]
The reaction gas used in the metal oxide layer forming method of the present invention will be described.
The reaction gas for forming the metal oxide layer preferably contains nitrogen or a rare gas. That is, the reaction gas is preferably a mixed gas of nitrogen or a rare gas and a reactive gas described below. Here, the rare gas may be an element belonging to Group 18 of the periodic table, specifically, each element such as helium, neon, argon, krypton, xenon, and radon. An element and an argon element can be preferably used. The concentration of the rare gas in the reaction gas is preferably at least 90% by volume in order to generate a stable plasma discharge, and is preferably from 90 to 99.99% by volume. The rare gas is used to generate a stable plasma discharge. In the plasma, the reactive gas is ionized or radicalized, and a thin film is formed by depositing or attaching to the surface of the base material.
[0165]
By using a reactive gas useful in the present invention to which reactive gases of various substances are added, thin films having various functions can be formed on a long resin film. For example, a low refractive index layer of an antireflection layer can be formed using a fluorine-containing organic compound or a silicon compound as a reactive gas.
[0166]
Further, by using an organometallic compound, a metal hydride, or a metal halide containing Ti, Zr, In, Sn, Zn, Ge, Si or another metal, these metal oxide layers (metal oxide nitride layers) are used. Or a metal nitride layer, etc., which may be a low-refractive-index layer, a medium-refractive-index layer, or a high-refractive-index layer of an antireflection layer, or a conductive layer or an antistatic layer. You can also. For example, by providing a tin oxide layer and an indium oxide layer, a surface resistivity of 10 ^-3 -10 ¹¹ Ω / cm ² Can be formed. These are preferably doped by a known method.
[0167]
Further, the antifouling layer and the low refractive index layer can be formed of a fluorine-containing organic compound, and the gas barrier layer and the low refractive index layer can be formed of a silicon compound. The present invention is particularly preferably used for forming an antireflection layer formed by alternately stacking high and medium refractive index layers and low refractive index layers.
[0168]
The thickness of the metal oxide layer formed in the present invention is preferably in the range of 1 to 1000 nm.
[0169]
In the atmospheric pressure plasma treatment, a fluorine compound-containing layer can be formed by using a fluorine-containing organic compound as a source gas. As the fluorine-containing organic compound, a fluorocarbon gas, a fluorohydrocarbon gas, or the like is preferable. Specifically, examples of the fluorine-containing organic compound include carbon fluoride compounds such as carbon tetrafluoride, carbon hexafluoride, ethylene tetrafluoride, propylene hexafluoride, and cyclobutane octafluoride; Fluorohydrocarbon compounds such as ethane tetrafluoride, propylene tetrafluoride, propylene trifluoride, and cyclobutane octafluoride; furthermore, methane monofluoride trifluoride, dichloromethane monofluoride, cyclobutane dichloride and the like And fluorine-substituted organic compounds such as alcohols, acids and ketones.
[0170]
These may be used alone or as a mixture. Examples of the fluorinated hydrocarbon gas include methane difluoride, ethane tetrafluoride, propylene tetrafluoride, and propylene trifluoride.
[0171]
Further, it is possible to use a fluoride of a hydrocarbon compound such as trifluoromethane trifluoride, methane dichloride methane, or cyclobutane difluoride or a fluorine-substituted organic compound such as alcohol, acid or ketone. Although possible, the present invention is not limited to these.
[0172]
Further, these compounds may have an ethylenically unsaturated group in the molecule. Further, the above compounds may be used as a mixture.
[0173]
When using a fluorine-containing organic compound as a reactive gas useful in the present invention, from the viewpoint of forming a uniform thin film on a long resin film by plasma discharge treatment, the fluorine-containing organic compound as a reactive gas in the reaction gas The content is preferably from 0.01 to 10% by volume, more preferably from 0.1 to 5% by volume.
[0174]
When the fluorine-containing organic compound preferably used in the present invention is a gas at normal temperature and normal pressure, it can be used as it is as a reactive gas component.
[0175]
Further, when the fluorine-containing organic compound is a liquid or solid at normal temperature and normal pressure, it may be used by evaporating it by a vaporizing means, for example, heating, reducing pressure, or the like, or may be used by dissolving in an appropriate organic solvent. .
[0176]
Examples of the silicon compound as a reactive gas useful in the present invention include, for example, dimethylsilane, organometallic compounds such as tetramethylsilane, metal hydrogen compounds such as monosilane and disilane, silane dichloride, silane trichloride, and silicon tetrafluoride. It is preferable to use, but not limited to, metal halogen compounds such as, for example, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, ethyltriethoxysilane, and other alkoxysilanes, and organosilanes. Not done.
[0177]
These can be used in appropriate combination. Alternatively, the properties of the film can be changed or controlled by adding another organic compound.
[0178]
In the present invention, when using a silicon compound as the reactive gas, from the viewpoint of forming a uniform thin film on the long resin film by discharge plasma discharge treatment, the content of the silicon compound as a reactive gas in the reaction gas is: It is preferably from 0.01 to 10% by volume, and more preferably from 0.1 to 5% by volume.
[0179]
The organometallic compound as a reactive gas useful in the present invention is not particularly limited, but Al, As, Au, B, Bi, Sb, Ca, Cd, Cr, Co, Cu, Fe, Ga, Ge, Hg , In, Li, Mg, Mn, Mo, Na, Ni, Pb, Pt, Rh, Se, Si, Sn, Ti, Zr, Y, V, W, Zn, etc. Can be mentioned.
[0180]
For example, in order to form a high refractive index layer as an antireflection layer, a titanium compound is preferable, and specifically, for example, an organic amino metal compound such as tetradimethylaminotitanium, a metal hydrogen compound such as monotitanium and dititanium, Examples thereof include metal halides such as titanium chloride, titanium trichloride, and titanium tetrachloride, and metal alkoxides such as tetraethoxytitanium, tetraisopropoxytitanium, and tetrabutoxytitanium.
[0181]
In the present invention, the silicon compound and the organometallic compound are preferably a metal hydrogen compound and a metal alkoxide from the viewpoint of handling. Alkoxides are preferably used.
[0182]
In the present invention, when an organometallic compound is used as the reactive gas, from the viewpoint of forming a uniform thin film on the long resin film by plasma discharge treatment, the content of the organometallic compound as the reactive gas in the reactive gas is: , 0.01 to 10% by volume, more preferably 0.1 to 5% by volume.
[0183]
In order to introduce a metal compound such as a silicon compound or a titanium compound into the discharge part, both can be used in a gas, liquid or solid state at normal temperature and normal pressure.
[0184]
In the case of gas, it can be directly introduced into the discharge section, but in the case of liquid or solid, it can be used after being vaporized by vaporizing means such as heating, decompression, and ultrasonic irradiation.
[0185]
When a metal compound such as a silicon compound or a titanium compound is vaporized by heating and used, a metal alkoxide which is liquid at ordinary temperature, such as tetraethoxysilane or tetraisopropoxytitanium, and has a boiling point of 200 ° C. or less is used in the present invention. It is suitable for a method of forming a metal oxide thin film layer. The metal alkoxide may be used after being diluted with an organic solvent. As the organic solvent, an organic solvent such as methanol, ethanol, isopropanol, butanol, n-hexane or a mixed organic solvent thereof can be used.
[0186]
Further, by including oxygen, hydrogen, carbon dioxide, carbon monoxide, nitrogen, nitrogen dioxide, nitrogen monoxide, ammonia and the like in the reaction gas in an amount of 0.1 to 10% by volume, physical properties such as hardness and density of the thin film layer can be improved. Can be controlled.
[0187]
By the above method, an amorphous metal oxide layer of silicon oxide, zirconium oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, or the like can be preferably formed. These metal oxide layers preferably have a surface roughness Ra of 0.1 to 10 nm.
[0188]
The optical film of the present invention can be preferably used, for example, as an optical film having an antireflection layer in which a low refractive index layer and a high refractive index layer are laminated, or a conductive layer or an optical film having an antistatic layer.
[0189]
In the present invention, by providing a plurality of plasma discharge devices, a multilayer thin film can be continuously provided, and a multilayer laminate can be formed without unevenness of the thin film.
[0190]
For example, when producing an optical film having an antireflection layer on a long resin film, a high refractive index layer having a refractive index of 1.6 to 2.3 and a low refractive index layer having a refractive index of 1.3 to 1.5 are used. It can be laminated efficiently on the surface of a long resin film and efficiently produced.
[0191]
As the low refractive index layer, a fluorine-containing compound layer formed by plasma discharge treatment of a gas containing a fluorine-containing organic compound, or silicon oxide formed mainly by plasma discharge treatment using an organosilicon compound such as alkoxysilane is used. A metal oxide layer having a metal oxide layer formed by plasma discharge treatment of a gas containing an organometallic compound, such as a layer having titanium oxide, zirconium oxide, tin oxide, or zinc oxide, is preferable as the high refractive index layer. Is preferred.
[0192]
The above-described method for forming the metal oxide layer and the like is an example of a preferable method, and the present invention is not limited to these, and the layer configuration is not limited to these. For example, the antifouling layer may be provided on the outermost surface by performing a plasma discharge treatment in the presence of a fluorine-containing organic compound gas at or near atmospheric pressure.
[0193]
According to the present invention, in the present invention, a multilayer thin film can be laminated, and a uniform optical film can be obtained without unevenness in the thickness of each layer.
[0194]
The optical film of the present invention is characterized in that a metal oxide layer is formed directly or via another layer on a long resin film, but it is more preferable that the metal oxide layer is formed via a cured resin layer or another layer. preferable. It is preferable to form a thermosetting resin layer or an actinic ray curable resin layer on the long resin film obtained as described above, and it is particularly preferable to provide an ultraviolet curable resin layer.
[0195]
The cured resin layer may have various functions, for example, an antiglare layer or a clear hard coat layer. The cured resin layer is preferably a layer formed by polymerizing a component containing at least one monomer having an ethylenically unsaturated bond. As the resin layer formed by polymerizing a component containing a monomer having an ethylenically unsaturated bond, a layer formed by curing an active ray-curable resin or a thermosetting resin is preferably used, and particularly preferably used. An actinic radiation curable resin layer. Here, the actinic radiation-curable resin layer refers to a layer mainly composed of a resin which cures through a crosslinking reaction or the like by irradiation with actinic rays such as ultraviolet rays or electron beams.
[0196]
Typical examples of the actinic radiation curable resin include an ultraviolet curable resin and an electron beam curable resin, but a resin which is cured by irradiation with actinic rays other than ultraviolet rays and electron beams may be used.
[0197]
Examples of the ultraviolet-curable resin include an ultraviolet-curable acrylic urethane-based resin, an ultraviolet-curable polyester acrylate-based resin, an ultraviolet-curable epoxy acrylate-based resin, an ultraviolet-curable polyol acrylate-based resin, and an ultraviolet-curable epoxy resin. Can be.
[0198]
Specific examples include, for example, trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, and alkyl-modified dipentaerythritol pentaacrylate.
[0199]
As the UV-curable acrylic urethane resin, generally, a product obtained by reacting an isocyanate monomer or a prepolymer with a polyester polyol is further added with 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate (hereinafter, acrylate includes methacrylate). And acrylate-based monomers having a hydroxyl group such as 2-hydroxypropyl acrylate, which are easily formed, and those described in JP-A-59-151110. Can be used.
[0200]
Examples of the UV-curable polyester acrylate resin include those easily formed by reacting a polyester polyol with 2-hydroxyethyl acrylate and 2-hydroxy acrylate monomers, as disclosed in JP-A-59-151112. Those described can be used.
[0201]
Specific examples of the ultraviolet-curable epoxy acrylate-based resin include those formed by making epoxy acrylate an oligomer, adding a reactive diluent and a photoreaction initiator thereto, and reacting the oligomer. No. 105738 can be used.
[0202]
Specific examples of these photoreaction initiators include benzoin and derivatives, acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and the like, and derivatives thereof. You may use together with a photosensitizer.
[0203]
The above-mentioned photoinitiator can also be used as a photosensitizer. When an epoxy acrylate photoreactive agent is used, a sensitizer such as n-butylamine, triethylamine, and tri-n-butylphosphine can be used.
[0204]
Examples of the resin monomer include, as one monomer having one unsaturated double bond, general monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, benzyl acrylate, cyclohexyl acrylate, vinyl acetate, and styrene. Further, monomers having two or more unsaturated double bonds include ethylene glycol diacrylate, propylene glycol diacrylate, divinylbenzene, 1,4-cyclohexane diacrylate, 1,4-cyclohexyldimethyl adiacrylate, and the above-mentioned trimethylolpropane. Examples thereof include triacrylate and pentaerythritol tetraacrylic ester.
[0205]
Commercially available UV curable resins that can be used in the present invention include ADEKA OPTOMER KR / BY series: KR-400, KR-410, KR-550, KR-566, KR-567, BY-320B (Asahi Denka ( Koeihard A-101-KK, A-101-WS, C-302, C-401-N, C-501, M-101, M-102, T-102, D-102, NS -101, FT-102Q8, MAG-1-P20, AG-106, M-101-C (manufactured by Koei Chemical Co., Ltd.); Seika Beam PHC2210 (S), PHC X-9 (K-3), PHC2213, DP -10, DP-20, DP-30, P1000, P1100, P1200, P1300, P1400, P1500, P1600, SCR900 (manufactured by Dainichi Seika Kogyo Co., Ltd.) KRM7033, KRM7039, KRM7130, KRM7131, UVECRYL29201, UVECRYL29202 (manufactured by Daicel UCB); RC-5015, RC-5016, RC-5020, RC-5031, RC-5100, RC-5102, RC-5120. , RC-5122, RC-5152, RC-5171, RC-5180, RC-5181 (manufactured by Dainippon Ink and Chemicals, Inc.); 340 Clear (China Paint Co., Ltd.); Sunrad H-601 (Sanyo Chemical Industry Co., Ltd.); SP-1509, SP-1507 (Showa Kogaku Co., Ltd.); RCC-15C (Grace Japan ( Co., Ltd.), Aronix M-6100, M-8030, M-8060 (manufactured by Toagosei Co., Ltd.) and the like can be appropriately selected and used.
[0206]
These actinic ray-curable resin layers can be applied by a known method.
As a light source for curing the ultraviolet curable resin by a photocuring reaction, any light source that generates ultraviolet light can be used without limitation. For example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, and the like can be used. Irradiation conditions differ depending on each lamp, but the irradiation light amount is 20 to 10000 mJ / cm. ² About 50 to 2000 mJ / cm. ² It is. In the region from the near ultraviolet region to the visible light region, it can be efficiently formed by using a sensitizer having an absorption maximum in that region.
[0207]
As the organic solvent of the UV curable resin layer composition coating liquid, for example, hydrocarbons, alcohols, ketones, esters, glycol ethers, and other organic solvents are appropriately selected or mixed and used. it can. For example, propylene glycol monoalkyl ether (1 to 4 as the number of carbon atoms in the alkyl group) or propylene glycol monoalkyl ether acetate (1 to 4 as the number of carbon atoms in the alkyl group) is 5% by mass or more, more preferably 5% by mass or more. It is preferable to use the above-mentioned organic solvent containing 80% by mass.
[0208]
As the method of applying the ultraviolet-curable resin composition coating solution, the above-described methods can be used. The coating amount is appropriately from 0.1 to 30 μm as a wet film thickness, and preferably from 0.5 to 15 μm. The ultraviolet curable resin composition is preferably irradiated with ultraviolet light during or after coating and drying, and the irradiation time is preferably 0.5 seconds to 5 minutes, and 3 seconds from the viewpoint of curing efficiency or work efficiency of the ultraviolet curable resin. ~ 2 minutes is more preferred.
[0209]
In order to prevent blocking, and to enhance abrasion resistance, etc., fine particles of an inorganic compound or an organic compound can be added to the coating solution of the cured resin layer. It is almost the same as The average particle size of these fine particle powders is preferably from 0.005 to 5 μm, particularly preferably from 0.01 to 1 μm. The ratio of the ultraviolet curable resin composition to the fine particle powder is preferably 0.1 to 20 parts by mass based on 100 parts by mass of the resin composition.
[0210]
Even if the ultraviolet curable resin layer is a clear hard coat layer having a center line average roughness (Ra) defined by JIS-B-0601 of 1 to 50 nm, it is an antiglare layer having a Ra of 0.1 to 1 μm. Is also good. Further, the refractive index of the ultraviolet curable resin layer is preferably from 1.5 to 1.7, and more preferably from 1.52 to 1.65. Further, two or more ultraviolet curable resin layers may be laminated.
[0211]
According to the present invention, in an antireflection film in which at least one metal oxide layer is provided on a long resin film having a width of 1 m or more, the occurrence of cracks in the metal oxide layer is small, and the metal oxide layer is provided. In this case, streak unevenness occurring at the end can be significantly reduced. As a result, it is possible to provide a large-sized display device exceeding 20 inches in high yield. The antireflection film of the present invention can be used as a polarizing plate in a large liquid crystal display device by a known method, or can be preferably used in various display devices such as an organic EL display, an inorganic EL display, and a plasma display.
[0212]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples, but embodiments of the present invention are not limited thereto.
[0213]

Each of the above compositions was put into a closed vessel in order, and the temperature in the kettle was raised to 70 ° C., followed by stirring at 70 ° C. for 3 hours to completely dissolve each composition. Thereafter, the stirring was stopped, the liquid temperature was lowered to 43 ° C., and the dope was prepared. Then, the liquid was immediately sent to a filtration step described below through a connected pipe, using a filter paper having an absolute filtration accuracy of 0.005 mm and a filtration flow rate of 300 L. / M ² ・ Time, filtration pressure 1.0 × 10 ⁶ Filtration was performed with Pa.
[0214]
<< Preparation of Cellulose Ester Films 1-9 >>
The dope prepared above was cast and dried using a solution casting film-forming cellulose ester film production apparatus having a tenter drying apparatus shown in FIG. 2 to produce a cellulose ester film. However, the one except for the first roll drying device 6 shown in FIG. 2 was used.
[0215]
The dope solution prepared above is cast on a metal support 1 made of a stainless steel belt through a die 2, the temperature of the stainless steel belt is controlled to 25 ° C., and a 45 ° C. Is applied obliquely at a wind speed of 10 m / sec, and from the drying step 3 on the stainless steel belt side, the first half is vertically blown with a wind of 40 ° C. at 10 m / sec to dry the film. After evaporating the solvent until the peeling, the film was peeled off by the peeling roll 5.
[0216]
Next, the film is introduced into the tenter drier 8 and the roll drier 9 and dried at 105 ° C. while maintaining the width in the tenter drier 8. Dried at 20 ° C., wound up by the winder 72 of the winding section 7 and finally cooled to 20 ° C. to produce a cellulose ester film 1 (also referred to as a film sample 1) having a thickness of 60 μm and a width of 1.4 m. did. In addition, the conveyance speed of the stainless steel belt and the winding speed of the winding machine were appropriately adjusted so that the tension at the time of conveying the film was 196 N / width throughout the entire process.
[0219]
Next, in the production of the above film sample 1, each transport tension condition and peeling were performed so that the expansion ratio A in the width direction, the expansion ratio B in the transport direction, and the ratio (A / B) became the values shown in Table 1. The amount of residual solvent at the time, the stretching conditions in a tenter, the drying temperature and the film thickness were appropriately adjusted to produce cellulose ester films 2 to 9 (film samples 2 to 9).
[0218]
(Measurement of expansion ratio A in the width direction and expansion ratio B in the transport direction)
The expansion ratio A in the width direction and the expansion ratio B in the transport direction were measured according to the following formula.
[0219]
Equation (1)
Expansion / contraction ratio A in the width direction = (film width at winding / film width on metal support−1) × 100 (%)
Equation (2)
Expansion / contraction ratio B in the transport direction = (film transport speed at winding / film transport speed on metal support-1) × 100 (%)
In the above formula (1), marking of a constant width was performed in the width direction of the film on the metal support shown in FIG. Next, the film is dried through a tenter drying device 8 and roll drying devices 6 and 9 until the residual solvent amount of the film becomes 1% by mass or less, and a sample is sampled immediately before the winder 72 of the winder 7. Then, the length of the marking was measured by a measure, and using this, the expansion / contraction rate A in the width direction was calculated. Further, when the film is conveyed at a tension of 196 N / width, the film being conveyed does not slack and all the conveying rolls normally follow the film conveying speed on the metal support and the film conveying speed at the time of winding. In this state, the transport speed was adjusted optimally so that the film would not be pulled excessively or the film edge would not break due to excessive tension, and the transport speed at that time was determined.
[0220]
<< Evaluation of cellulose ester film >>
The retardation value Ro, the slow axis angle θ, and the dimensional stability of each cellulose ester film produced as described above were measured according to the following methods.
[0221]
(Measurement of average film thickness d, retardation value Ro, slow axis angle θ)
The retardation value Ro was measured using an automatic auxiliary refractometer KOBRA-21ADH (manufactured by Oji Scientific Instruments) in an environment of 23 ° C. and 55% RH, and a laser focus displacement meter LT- manufactured by Keyence Corporation was used. The film thickness of the film is measured by 8010, the average film thickness d is obtained, and the film thickness is measured at 10 points in the width direction of the sample according to the method described above, and the maximum retardation value Ro and the slow axis angle θ in the transport direction Was set to 0 degree, the maximum value of the slow axis angle θ in the width direction was measured. Table 1 shows the measurement results.
[0222]
[Table 1]

[0223]
The following clear hard coat layer is formed on the cellulose ester films 1 to 9, and a tin oxide layer is further formed thereon by a plasma treatment, and the layer structure includes a cellulose ester film / clear hard coat layer / tin oxide layer. Optical films 1 to 9 were prepared.
[0224]
(Clear hard coat layer)
The following clear hard coat layer coating composition was applied to the B side of the cellulose ester film (the side of the film where the web was in contact with the stainless steel belt) with an extrusion coater so that the liquid film thickness became 13 μm, and then 80 120mJ / cm after drying in the drying unit set at ² And a clear hard coat layer having a center line average roughness (Ra) of 13 nm in a dry film thickness was provided.
[0225]

(Tin oxide layer)
A tin oxide layer (metal oxide layer) was formed on a cellulose ester film by atmospheric pressure plasma CVD. The apparatus shown in FIG. 3 was used for the atmospheric pressure plasma discharge treatment. As the roll electrode, a stainless steel jacket roll base material having a cooling function by circulating silicone oil was used.
[0226]
This was coated with alumina by ceramic spraying to a thickness of 1 mm, coated with a solution of tetramethoxysilane diluted with ethyl acetate, dried, cured by irradiation with ultraviolet light, sealed, and subjected to Rmax, a roll electrode having a 1 μm dielectric. Was manufactured and grounded.
[0227]
On the other hand, as a counter electrode, a hollow stainless steel pipe was coated with a dielectric material similar to the above under the same conditions to form an opposing electrode group. As the power source of the plasma CVD processing apparatus, a high frequency power source manufactured by Pearl Industries was used, the continuous frequency was set to 2 MHz, and 4 W / cm ² Power was supplied. However, the roll electrode was rotated using a drive in synchronization with the conveyance of the long resin film.
[0228]
The electrode gap is 2 mm, the pressure of the reaction gas is +1 kPa with respect to the atmospheric pressure, and a 0.1 μm-thick metal oxide layer (tin oxide layer, surface resistivity 10 ¹⁰ Ω / cm ² Less). The composition of the reaction gas used in the plasma discharge treatment is described below.
[0229]
<Reaction gas for forming metal oxide layer>
Inert gas (helium) 99.2% by volume
Reaction gas (oxygen gas) 0.4% by volume
Reaction gas (tetrabutyltin vapor) 0.4% by volume
With respect to the produced optical film, cracks at the end portions and stripe unevenness were evaluated according to the following methods. Table 2 shows the results of the evaluation.
[0230]
(crack)
The optical film was treated at 80 ° C. and 90% RH for 72 hours, and cracks generated in a metal oxide layer (anti-reflection layer) formed on the film surface at a position 10 cm from the edge of the film were visually observed and observed with a microscope. The evaluation rank is as follows.
[0231]
：: Almost no cracks observed and excellent transparency
：: Cracks are observed but no cloudiness
Δ: Cracks were observed and slightly clouded
×: markedly cracked and clouded
(Streak unevenness)
The streak-like unevenness occurring at the end of the width of the optical film was visually evaluated as follows.
[0232]
：: No unevenness visually observed at a length of 100 m or more in the longitudinal direction.
：: Weak unevenness is observed every tens of meters in a portion about 10 cm from the end.
Δ: Intermittent unevenness is observed in a portion about 10 cm from the end.
×: Intermittently strong unevenness is observed in a portion about 10 cm from the end.
[0233]
[Table 2]

[0234]
As is clear from Table 2, the ratio (A) of the expansion / contraction rate A in the width direction represented by the above formula (1) defined in the present invention to the expansion / contraction rate B in the transport direction represented by the above equation (2) / B) is 2.0 to 10.0, and an optical film having a metal oxide layer formed thereon using a cellulose ester film having an expansion / contraction ratio B of -0.5% or less in the transport direction is It was confirmed that the occurrence of cracks at the ends was suppressed, and the occurrence of streak-like unevenness at the ends was small.
[0235]
Example 2
<Formation of anti-glare layer>
On one surface of the cellulose ester films 1 to 9 produced in Example 1, an antiglare layer (ultraviolet curable resin layer) was formed as described below.
[0236]

Was mixed with a solvent (ethyl acetate) using a homogenizer to prepare a homogeneous dispersion having a volatile matter concentration of 50% by mass.
[0237]
This was applied on the above film, dried at 90 ° C. for 2 minutes, and then dried at 110 mJ / cm. ² To cure the film to form an antiglare layer having a thickness of 3 μm. This was immersed in a 2 mol / L NaOH aqueous solution at 50 ° C. for 90 seconds, alkali-treated (saponified), washed with water and dried.
[0238]
<Formation of antireflection layer>
On the antiglare layer produced above, the following layers (metal oxide layers) were sequentially formed to form an antireflection layer, and optical films 10 to 18 were obtained.
[0239]
(Anti-reflective layer)
Titanium oxide layer (refractive index 2.10, thickness 0.02 μm)
Silicon oxide layer (refractive index: 1.45, film thickness: 0.03 μm)
Titanium oxide layer (refractive index 2.10, film thickness 0.12 μm)
Silicon oxide layer (refractive index: 1.45, thickness: 0.08 μm)
The oxide layer was formed in the same manner as in Example 1 except that the plasma discharge treatment apparatus used in Example 1 was used and the following gas was used as a reaction gas for forming a metal oxide layer.
[0240]
<Reaction gas for forming titanium oxide layer>
Helium 99.4% by volume
Oxygen 0.3% by volume
0.3 volume% of tetraisopropoxy titanium
<Reaction gas for forming silicon oxide layer>
Helium 99.3% by volume
0.4% oxygen
0.3% by volume of tetraethoxysilane
About the produced optical film, the crack of the edge part and the stripe unevenness were evaluated like Example 1. FIG. Table 3 shows the results of the evaluation.
[0241]
[Table 3]

[0242]
Example 3
<< Preparation of polarizing plate >>
Using the optical films 10 to 18 produced in Example 2, polarizing plates 10A to 18A were produced according to the method described below.
[0243]
A polyvinyl alcohol film having a thickness of 120 μm was immersed in 100 kg of an aqueous solution containing 1 kg of iodine and 4 kg of boric acid, and stretched 6 times at 50 ° C. to form a polarizing film. An optical film 10 was used on one side of the polarizing film, and a cellulose ester film (cellulose ester film 1 in the case of the optical film 10) used as a base material of the optical film 10 was applied to the other side of the polarizing film by the following alkali saponification treatment. After performing, a completely saponified polyvinyl alcohol 5% aqueous solution was used as an adhesive to bond each to produce a long polarizing plate 10A.
[0244]

Under the above conditions, each cellulose ester film was subjected to saponification, water washing, neutralization, and water washing in this order, and then dried at 80 ° C.
[0245]
The optical film 10 was changed to the optical films 11 to 18 and the cellulose ester film was also changed to the cellulose ester films 2 to 9 used therein, to obtain polarizing plates 11A to 18A.
[0246]
Since the polarizing plates 10A to 15A according to the present invention have less unevenness and cracks up to the end, even when cut out to a size of 20 inches or more, the yield was excellent. On the other hand, in the comparative polarizing plates 16A to 18A, the stripe unevenness was conspicuous at the end and the crack was remarkable, so that this portion could not be used, and the yield was remarkably reduced.
[0247]
Example 4
A norbornene resin film was prepared by a solution casting method in the same manner as in Example 1 except that a dope having the following composition was prepared using a norbornene resin instead of the cellulose ester. In the production of the film, the transport tension conditions and the residual solvent amount at the time of peeling were set such that the stretch ratio A in the width direction, the stretch ratio B in the transport direction, and the ratio (A / B) became the values shown in Table 4. The stretching conditions in the tenter, the drying temperature and the film thickness were adjusted as appropriate.
[0248]
《Norbornene resin solution (dope)》
100 parts by mass of norbornene resin (ARTON G, manufactured by JSR Corporation)
233 parts by mass of methylene chloride
The obtained norbornene resin film was measured for retardation value Ro, slow axis angle θ, and evaluated for dimensional stability in the same manner as in Example 1. Table 4 shows the results.
[0249]
[Table 4]

[0250]
A clear hard coat layer was provided on the obtained norbornene resin film in the same manner as in Example 1, and a tin oxide layer was formed thereon to obtain optical films 19 to 25. With respect to this optical film, cracks at the end portions and stripe unevenness were evaluated in the same manner as in Example 1. Table 5 shows the results.
[0251]
[Table 5]

[0252]
In the optical film of the present invention, cracks and streak unevenness were not observed at the edges even with a film exceeding 1 m in width, whereas the yield of the comparative film was significantly reduced due to cracks and streak unevenness.
[0253]
【The invention's effect】
According to the present invention, it is possible to provide an optical film with less stripe unevenness and cracks, a method for manufacturing the same, a polarizing plate and a display device using the same.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of an apparatus for producing a long resin film by solution casting.
FIG. 2 is a schematic view showing an example of a solution casting film forming long resin film manufacturing apparatus having a tenter drying apparatus.
FIG. 3
FIG. 2 is a view showing an example of a plasma CVD processing apparatus used for forming a metal oxide thin film layer of the present invention.
FIG. 4 is a diagram showing an example of a plasma CVD processing apparatus having a rotating electrode and a fixed electrode useful for forming a metal oxide thin film layer of the present invention.
[Explanation of symbols]
F film (also called web)
P Long resin film
G reaction gas
G 'exhaust gas
1 Metal support
2 dies
3, 4 drying process
5 Release roll
6, 9 roll dryer
7 Winding unit
8 Tenter dryer
61 Dry gas style
63 rolls
72 winder
110A, 110B, 110 rotating electrode
111A, 111B, 111C, 111D U-turn roll
120, 121 Guide roll
130 Reaction gas supply unit
140, 240 Gas exhaust port
150, 250 discharge unit
180, 280 power supply
182, 281 Voltage supply means
210 rotating electrode
211 fixed electrode
220, 221 Guide roll
222, 223 Nip roll
224, 225 partition plate
230 air supply pipe
231 Reaction gas generator
290 Plasma CVD processing container

Claims (13)

The resin solution was cast on a metal support by a solution casting film-forming method, and the peeled film was dried while gripping both ends of the width and regulating the width dimensions. In the process during which the film is dried to a mass% or less and wound up, the expansion and contraction ratio A in the width direction represented by the following formula (1) and the expansion and contraction ratio B in the transport direction represented by the following expression (2) are obtained. To produce a long resin film such that the ratio (A / B) is 2.0 to 10.0 and the expansion / contraction ratio B is -0.5% or less, and directly or on another resin film. A method for producing an optical film, comprising forming a metal oxide layer via a coating layer.
Equation (1)
Expansion / contraction ratio A in the width direction = (film width at winding / film width on metal support−1) × 100 (%)
Equation (2)
Expansion / contraction ratio B in the transport direction = (transport speed of film at winding / film transport speed on metal support-1) × 100 (%) The method for producing an optical film according to claim 1, wherein the amount of the residual solvent when peeled from the metal support is 20 to 150% by mass. 3. The method for producing an optical film according to claim 1, wherein A / B is 2.5 to 8.0. The method for producing an optical film according to any one of claims 1 to 3, wherein the metal oxide layer is formed by plasma CVD. The method for producing an optical film according to any one of claims 1 to 4, wherein the metal oxide layer is formed by applying a composition containing a metal oxide. The method for producing an optical film according to any one of claims 1 to 5, wherein the resin solution contains a cellulose ester or a norbornene resin. An optical film produced by the method according to claim 1. When the angle between the longitudinal direction of the long resin film and the in-plane slow axis direction is θ, the absolute value of θ is less than 5 °, and the in-plane retardation value Ro is 0.5 to 7 nm. An optical film having a metal oxide layer directly on a long resin film or via another coating layer. The optical film according to claim 8, wherein the absolute value of θ is less than 1 °. The optical film according to any one of claims 7 to 9, wherein the resin is a cellulose ester or a norbornene-based resin. The optical film according to any one of claims 7 to 10, wherein the long resin film has a thickness of 10 to 70 µm. A polarizing plate, comprising the optical film according to any one of claims 7 to 11 on at least one surface. A display device comprising the optical film according to claim 7.

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