201211596 六、發明說明： 【發明所屬之技術領域】 本發明係關於一種聚乙烯醇系偏光膜之製造方法，詳細 而言’係關於一種降低偏光膜之與吸收軸正交之方向上之 收縮率，並且染色效率亦優異之偏光膜之製造方法。另外， 本發明亦關於一種於藉由該方法所獲得之偏光膜之至少一 面上貼合透明保護膜而製造偏光板之方法。 【先前技術】 偏光板通常構成為：於包含吸附定向有二色性色素之聚 乙烯醇系樹脂之偏光膜之一面或兩面上，經由接著劑層積 層透明保護膜、例如以三乙酸纖維素為代表之乙酸纖維素 系透明保護膜。視需要經由其他光學膜並利用黏著劑將其 貼合於液晶單元上，而製成液晶顯示裝置之構成零件。 作為偏光膜之製造方法，例如於jPHi〇_i53 709-A中纪載 有如下之方法：將聚乙烯醇系樹脂膜浸潰於水中使其膨潤 後，利用碘進行染色，其次進行延伸，進而為了使碘定著 而進行硼酸處理，水洗後進行乾燥。利用水之膨潤處理係 為了於染色前使膜均勻地膨潤，縮短染色時間，改善染色 不均等而進行。此時，就抑制染色不均等之觀點而言，於 JPH1(M53709_A中係使膨潤處理浴中含有硼酸。又，於該 JPH1(M53709_a中，染色後將膜浸潰於含有硼酸之水溶液 中進行延伸，其後再次浸潰於硼酸水溶液中，進行利用交 聯之耐水化處理（於該文獻中稱作定著或固定）。 經過膨潤處理、染色處理及乾燥處理而製造之偏光膜若 156977.doc ⑧ 201211596 • 暴露於高溫條件下，則由於使用爛酸作為交聯劑而進行棚 酸交聯，不僅於製造時之機械方向（MD，Machine Directi〇n) 即吸收方向上收縮，並且亦於與吸收軸正交之方向（td ’201211596 6. TECHNOLOGICAL FIELD OF THE INVENTION The present invention relates to a method for producing a polyvinyl alcohol-based polarizing film, and in detail relates to a method for reducing shrinkage in a direction orthogonal to an absorption axis of a polarizing film. And a method of producing a polarizing film which is excellent in dyeing efficiency. Further, the present invention relates to a method of producing a polarizing plate by laminating a transparent protective film on at least one surface of a polarizing film obtained by the method. [Prior Art] The polarizing plate is generally configured to laminate a transparent protective film, for example, cellulose triacetate, via an adhesive layer on one or both sides of a polarizing film containing a polyvinyl alcohol-based resin to which a dichroic dye is adsorbed. A cellulose acetate-based transparent protective film. The constituent members of the liquid crystal display device are formed by bonding them to the liquid crystal cell via another optical film as needed. As a method of producing a polarizing film, for example, jPHi〇_i53 709-A contains a method in which a polyvinyl alcohol-based resin film is immersed in water and swelled, and then dyed with iodine, followed by stretching, and further In order to fix the iodine, the boric acid treatment is carried out, and after washing with water, it is dried. The swelling treatment by water is carried out in order to uniformly swell the film before dyeing, shorten the dyeing time, and improve dyeing unevenness. In this case, in the case of suppressing dyeing unevenness, in the case of JPH1 (M53709_A, the swelling treatment bath contains boric acid. Further, in the JPH1 (M53709_a, the film is immersed in an aqueous solution containing boric acid for stretching after dyeing). Then, it is again immersed in an aqueous solution of boric acid, and subjected to a water-resistant treatment by cross-linking (referred to as fixing or fixing in the literature). A polarizing film produced by swelling treatment, dyeing treatment, and drying treatment is 156977.doc 8 201211596 • Exposure to high temperature conditions, due to the use of rotten acid as a cross-linking agent for linal acid cross-linking, not only in the manufacturing direction (MD, Machine Directi〇n), ie, the absorption direction shrinks, but also Absorption axis orthogonal direction (td '
Transverse Direction)上收縮。 • ;Ρ2ί)()1_141926·Α中記載有如下之方法：為了抑制染色不 均’將聚乙稀醇系樹脂膜浸潰於水浴中使其膨潤，並且於 該浴中進行初始狀態之Η〜4倍之延伸處理，其後，實施利 用二色性色素之染色處理及交聯處理，而製造偏光膜。於 該文獻之實施例1中，於膨潤浴中設為2倍之延伸倍率其 後，於埃染色浴及硼酸處理浴中亦分別進行延㈣理，最 終設為6.5倍之總延伸倍率，另外於實施彳糾，於膨潤浴 中設為2.5倍之延伸倍率，其後，於料色浴及硼酸處理浴 中亦分別進行延伸處理，最終設為6倍之總延伸倍率。該文 獻中所揭示之方法雖然對抑制染色不均有效，但根據轉 明者等人之實驗可知，若僅於膨潤浴中以實施例所示之程 度之倍率進行延伸，則最終所得之偏光膜暴露於高溫條件 下時之收縮依然較大。 另-方面，㈣㈣翁Α中記载有：使聚乙歸醇系相 脂膜依序於膨潤處理、染色處理及㈣處理之浴中連續知 進行處理，且於料中之至少―個步财進行單轴延伸而 製造偏光膜時’於膨潤處理與染色處理之間設置渴式 步驟，於㈣歧❹財，藉由❹顯讀液，於1 水溶液以1.〗倍以上且未達3倍之延伸倍率進行單轴延伸 而實現色不均之進-步改善。又，㈣队249766_A中 156977.doc 201211596 有：如上述JP2005-U4990-A中所揭示，於膨潤處理與染色 處理之間設置以1.1倍以上之延伸倍率進行單軸延伸的濕 式延伸步驟之情形時，由於在所得之長條偏光膜之寬度 向中央部與端部色相容易產生不均，故而於膨潤處理與染 色處理之間設置水浸潰處理步驟，並使此處之延伸倍率成 為1.05倍以下。 如上所述，若經過膨潤處理、染色處理、硼酸處理及乾 燥處理而製造之偏光膜暴露於高溫條件下，則不僅於吸收 方向（MD)上收縮，並且亦於與吸收軸正交之方向（TD)上收 縮。並且於先前所採用之偏光膜之製造方法中，難以抑制 此種收縮，尤其是與吸收軸正交之方向上之收縮。因此， 本發明所欲解決之課題在於提供一種降低偏光膜暴露於高 溫條件下時之收縮率，尤其是與吸收軸正交之方向上之收 縮率’另外染色性亦優異的偏光膜之製造方法。 【發明内容】 即本發明包含下述者。 [1] 一種偏光膜之製造方法’其包含：依序連續地實施使聚 乙婦醇系樹月曰原料片材膜通過膨潤槽之膨潤處理、通過染 色槽之染色處理及通過硼酸槽之硼酸處理，且於染色處理 及删酸處理中之至少一個處理中進行單軸延伸；該膨潤處 理係一面對上述聚乙烯醇系樹脂原料片材膜進行單軸延伸 一面進行’且膨湖處理中之單抽延伸之比例相對於自上述 原料片材膜起至獲得偏光膜為止之總延伸倍率為5 〇 %以 156977.doc . 6. ⑧ 201211596 m如π]之偏光膜之製造方法’其中_處理係於心贼 之溫度下進行。 ⑴如⑴或[2]之偏光狀製造μ，其巾_處理係於實 質上無溶解成分之純水中進行。 [4] -種偏光板之製造方法’其包含：利用如⑴至⑴中任 一項之方法製造偏光膜，並於所得之偏光膜之__面或兩面 上貼合保護膜。 根據本發明之方法，可製造染色效率高，且較低地抑制 與吸收軸正交之方向上之吸收率之偏光膜。 【實施方式】 以下詳細地說明本發明。於本發明中，依序連續地實施 使聚乙烯醇系樹脂原料片材膜通過膨潤槽之膨潤處理、通 過染色槽之染色處理及通過硼酸槽之硼酸處理，且於染色 處理及硼酸處理中之至少一個處理中進行單轴延伸而製造 偏光膜。就以此種方式連續地進行處理之關係方面而言， 聚乙烯醇系樹脂原料片材膜通常以輥狀供給。圖丨中模式性 地表不適於實施本發明之偏光膜之製造方法的裝置之配置 例。 於圖1所示之例中，自原料片材輥2抽出之聚乙烯醇系樹 脂原料片材膜1依序通過用以進行膨潤處理之膨潤槽3、用 以進行染色處理之染色糟4、及用以進行硼酸處理之硼酸槽 5 °自删酸槽5出來後之聚乙烯醇系樹脂膜通常通過水洗槽 6 ’而洗去於此前之槽中附著之未反應之硼酸水溶液，其 後’通過乾燥爐8進行乾燥，而獲得偏光膜9。雖然省略圖 156977.doc 201211596 示’但其後通常於所得之偏光膜之至少—面上貼合透明保 遵膜而成為偏光板。 並且，於本發明中，於經過上述各處理而製造偏光膜時， 通過膨_ 3時所進行之膨潤處理係-面對原料片材膜1進 行單軸延伸一面進行，且使該膨潤處理中之延伸倍率相對 於自原料片材膜1起至獲得偏光膜9為止之總延伸倍率的比 例成為5G%以上。於該膨潤處理中，係、使用將水作為主成 分之液體作為膨潤浴。 如此，本發明之偏光膜之製造方法較佳為包含以下之步 驟（1)〜(6) 〇 (υ使聚乙烯醇系樹脂原料片材膜1通過裝有將水作為主成 分之膨潤浴的膨潤槽3，使其與膨潤浴接觸而膨潤之膨潤處 理步驟； (2) 使經膨潤之聚乙烯醇系樹脂膜通過裝有含有二色性色 素之染色浴的染色槽4’於該染色浴中進行染色之染色處理 步驟； (3) 使經染色之聚乙烯醇系樹脂膜通過裝有含有硼酸之水 溶液的硼酸槽5，使其交聯之硼酸處理步驟； (4) 對聚乙烯醇系樹脂膜進行單軸延伸之延伸步驟； (5) 使經硼酸處理之聚乙烯醇系樹脂膜通過用以利用將水 作為主成分之溶液進行清洗的水洗槽6之水洗處理步驟；及 (6) 於水洗處理後通過乾燥爐8之乾燥步驟。 以下對成為原料片材之聚乙烯醇系樹脂膜及上述各步驟 依序進行詳細說明。 156977.doc . 8 - ⑧ 201211596 [聚乙烯醇系樹脂原料片材膜] 構成偏光膜之聚乙烯醇系樹脂係藉由使聚乙酸乙烯酯系 樹脂皂化而獲得。聚乙酸乙烯酯系樹脂除作為乙酸乙烯酯 之均聚物之聚乙酸乙烯酯以外，亦可為乙酸乙烯酯及可與 其共聚合之其他單體之共聚物。作為可與乙酸乙烯酯共聚 合之其他單體，例如可列舉不飽和羧酸類、不飽和磺酸類、 烯垣類、乙烯醚類等。聚乙烯醇樹脂之皂化度通常為85〜100 莫耳％左右，較佳為98〜100莫耳％、亦可進而對聚乙烯醇樹 脂進行改性，例如亦可使用以醛類進行改性之聚乙烯曱醛 或聚乙稀縮越等。 又，聚乙烯醇系樹脂之聚合度通常為1〇〇〇〜1〇〇〇〇左右， 較佳為1500〜5000。 使用將上述聚乙烯醇系樹脂製膜者作為偏光膜之原料片 材膜。將聚乙稀醇系樹脂製膜之方法並無特別限^，可使 用A知之方法製膜。聚乙烯醇系樹脂原料片材膜之膜厚並 無特別限定’例如為2〇〜1〇〇μΓη左右，較佳為叫。該 原料片材膜如上所述通常錢狀供給，其實用寬度於 1500〜6000 mm左右之範圍内。 [膨潤處理步驟] 首先於膨潤槽3中對原料片材膜1實施膨潤處理。該膨满 處理係為了去除膜表面之異物，去除膜中存在之可塑劑， 賦予下-步驟中之易染色性，對膜進行可塑化等而進行。 2本發明中’該膨潤處理步驟係藉由一面將原料片材膜1 ^於膨潤槽3中之膨潤浴中使其膨潤，-面進行單軸延伸 156977.doc 201211596 :進仃。並且’使膨潤處理步驟中之延伸倍率相對於自原 起至獲得偏光膜9為止之總延伸倍率的比例成為 。於本說Μ書巾，以τ有時將膨潤處理步驟中之 延:倍率相對於自原料片材膜味至獲得偏光膜9為止之總 申倍率的比例稱作「膨潤處理中之延伸倍率比」。該膨潤 理t之延伸倍率比較佳為6G%以上。藉由提高膨潤處理 之延伸倍率比，而於下—染色處理步驟中，二色性色素 2容易定向’可高效率地進行染色。又，於所得之偏光 、暴露於南溫條件下時，可較低地抑制與吸收軸正交之方 向上之收縮率。於本說明書中，以下有時將與偏光膜之吸 收軸正交之方向上之收縮率稱作「TD收縮率 於偏光膜暴露於高溫條件下時，就較低地抑制TD收縮率 之觀點而言’雖然增大膨潤處理中之延伸倍率比較為有 利，但另-方面，於本發明中，由於在其後之染色處理步 驟及蝴酸處理步驟中之至少—個㈣中進行單軸延伸，故 而膨潤處理中之延伸倍率比之上限通常至嶋為止。 膨潤處理步驟係藉由使原料片材膜〗通過裝有通常保持 C左右較佳為2 〇〜5 〇 〇之溫度的膨潤浴之膨潤槽3 而進行。此處之單軸延伸可藉由於膨潤槽3之入口側夾送輥 31與出口側夾送輥32之間對圓周速度設置差而進行。膨潤 處理之時間亦包含單軸延伸，通常為2〇〜3〇〇秒，較佳為 40〜240秒。 膨潤槽3中使用之膨潤浴除純水以外，亦可為於〇〇ι〜ι〇 重量％之範圍内添加有上述JpH1〇_1537〇9 A中所記載之硼 156977.doc ⑧ -10 - 201211596 ι、又以氯化物為代表例之無機鹽、以醇類為代表例之水 溶性有機溶劑等的水溶液。 其中於該膨潤槽3中較佳為使用實質上無溶解成分之純 水。 4湖處理步驟中，當產生膜於寬度方向上膨满而膜起 皺褶等問題之情形時，可利用擴幅輥、螺旋輥、中高輥、 =布報、f輥、拉幅夾等公知之擴幅裝置—面去除膜之敏 梏’-面搬送膜。為了使浴中之膜搬送穩定，而利用水中 喷水器控制膨潤浴中之水流’或併用EPC裝置（Edge Position C〇ntroller(對邊機控制器），即檢測膜之端部並防止 膜之蜿蜒的裝置）等亦有用。 [染色處理步驟] 匕將，過包含上述單軸延伸之膨㈣理後的聚乙烯醇系樹 膜交付至通過裝有包含二色性色素之染色浴的染色槽4 之染色處理步驟。二色性色素通常係使料或二色性之有 機染料。該染色處理係為了使二色性色素吸附定向於聚乙 稀醇系樹脂膜而進行，其條件係於可達成此種目的之範圍 内，且於膜不產生極端溶解、失透等不良情況之範圍内決 定。 、 於使用蛾作為二色性色素之情形時，較佳為將含有㈣ 峨化卸之水溶液作為染色洛。於此情形時，例如藉由於 1c、較佳為於2〇〜贼之溫度下，且於相對於水⑽ 重量份而含有魏003〜〇.2重量份及魏_ q ^ q重量份之 水溶液中浸潰10〜600秒、較佳為3〇〜2〇〇秒而進行染色處 156977.doc 201211596 理。亦可使用其他碘化物，例如碘化辞等代替碘化鉀，又， 亦可將其他碘化物與碘化鉀併用。於染色浴中，亦可使除 碘化物以外之化合物，例如硼酸、氯化辞、氣化鈷等共存。 再者，即使於添加硼酸之情形時，就處理浴含有碘之方面， 亦可與其後之硼酸處理加以區別。只要為相對於水1〇〇重量 份含有埃0.003重量份以上之浴，便可視為染心谷。就賦予 所得之偏光膜較高之偏光性能之觀點而言，較佳為使用碘 作為_色性色素。 另一方面，於使用水溶性之二色性染料作為二色性色素 之情形時，例如於20〜80°C、較佳為30〜的它之溫度下，且 將相對於水100重量份含有二色性染料〇 〇〇1〜〇丨重量份之 水溶液作為染色浴，於其中浸潰1〇〜6〇〇秒、較佳為2〇〜3〇〇 秒’藉此進行染色處理。使用之二色性染料之水溶液亦可 含有染色助劑等，例如可含有如硫酸鈉之無機鹽或界面活 性劑等《二色性染料可僅使用丨種，亦可根據所期望之色相 併用2種以上之二色性染料。 即使於染色處理步驟中，亦可與膨潤處理步驟同樣地將 擴幅輥 '螺旋輥、中高輥、導布輥、彎輥等適當地設置於 染色浴申及/或染色浴出入口。又，於染色步驟中，亦可同 時將膜沿機械方向（MD)進行單軸延伸。當於染色處理步驟 中進行單軸延伸之情形時，較佳為使其延伸倍率例如於 1.1〜3倍之範圍内。當於染色處理步驟中進行單軸延伸之情 形時，仍然可藉由在染色槽4中之入口側夾送輥41與出口側 夾送親42之間對圓周速度設置差而進行。 156977.doc ⑧ •12- 201211596 [硼酸處理步驟] 將染色處理後之聚乙稀醇系樹脂膜交付至删酸槽5中之 硼酸處理步驟。該硼酸處理係藉由將利用二色性色素進行 染色之聚乙稀醇系樹脂膜浸潰於蝴酸槽5中之棚酸水溶液 中而進行。硼酸水溶液中之硼酸之含量係於每丨〇〇重量份水 中通常為2~ 15重量份左右，較佳為3〜12重量份。於先前之 染色處理中’於使用職作為二色性色素之情形時，該硼酸 水溶液較佳為含有硤化鉀《於硼酸水溶液含有蛾化钟之情 形時’該碘化鉀之量係每100重量份水中通常為4〇重量份以 下，較佳為30重量份以下。又，該碘化鉀較佳為每1〇〇重量 份水中含有〇. 1重量份以上，進而較佳為含有1重量份以 上。於硼酸水溶液中之浸潰時間通常為6〇〜1，2〇〇秒左右， 較佳為60〜600秒，進而較佳為60-400秒。含有硼酸之水溶 液之溫度通常為50°C以上，較佳為50〜85°C，更佳為 55〜80〇C。 即使於硼酸處理步驟中，亦可於處理浴中同時使膜沿機 械方向（MD)進行單軸延伸。於硼酸處理步驟中進行單軸延 伸之情形，仍然可藉由在硼酸槽5中之入口側夾送輥51與出 口側夹送輥52之間對圓周速度設置差而進行。 [延伸處理步驟] 丨 於本發明之製造方法中，對聚乙烯醇系樹脂膜進行之單 軸延伸係於上述染色處理步驟及硼酸艇步驟中之至少一個 步驟中進行，進而亦可於上述膨潤處理步驟中進行。並且， 使膨潤處理步驟中之延伸倍率相對於自原料片材膜丨起至 156977.doc 13 201211596 獲得偏光膜9為止之總延伸倍率的比例、即上文定義之膨潤 處理中之延伸倍率比成為50%以上。 如此以於染色處理步驟及硼酸處理步驟中之至少—個步 驟中進行單軸延伸、及即使於膨潤處理步驟中亦進行單車由 延伸、使膨潤處理中之延伸倍率比成為50%以上為前提， 聚乙烯醇系樹脂膜之單軸延伸處理可進而於膨潤處理步驟 之前進行’亦可於膨潤處理步驟與染色處理步驟之間、染 色處理步驟及蝴酸處理步驟之後進行。但一般而言，較佳 為於膨潤處理步驟中進行如上所述之單軸延伸，進而於染 色處理步驟及鄉酸處理步驟之一方或雙方中進行單轴延 伸。 ， 膨潤處理步驟、染色處理步驟及硼酸處理步驟中之延伸 係藉由於各處理浴中經膨潤之狀態下之延伸即濕式延伸而 進行。於本發明中，如上所述’基本上係於染色處理步驟 及硼酸處理步驟中之至少一個步驟中、以及膨潤處理步驟 中進行延伸’因此較佳為以濕式進行所有之延伸。濕式之 單軸延伸一般係藉由使其通過圓周速度不同之輥而進行。 [水洗處理步驟] 硼酸處理步驟之後通常於水洗槽6中實施水洗處理。水洗 處理例如可藉由將經硼酸處理之聚乙烯醇系樹脂膜浸潰於 水中之方法、利用喷水器將水喷霧之方法、併用浸潰與喷 霧之方法等進行。水洗處理中之水之溫度通常為2〜40°C， 處理時間通常為2〜120秒。水洗處理可以^皆段進行，亦可 以多階段進行。於以多階段進行水洗處理之情形時，可於 156977.doc ⑧ -14· 201211596 卜個水洗槽巾機鹽之纽液騎處理。該情形下 制之無機鹽例如可為魏鉀、碘化納、破化鋅、氯化辞、 硫酸納、亞硫酸納等。該等無機鹽可使用】種，又，亦可併 .賴數種^進而亦可^洗槽中進行延伸，例如可延伸至 1.05〜1.2倍左右。 [乾燥步驟] 通常將水洗處理後之膜導入乾燥爐8中實施乾燥處理。該 乾燥係藉由通過至保持於4〇〜1〇〇ΐ之溫度、較佳為 50〜10(TC之溫度的乾燥爐8中花費3〇〜_秒左右而進行。乾 燥爐8可為複數個’於設置複數個乾燥爐之情形時，各乾燥 爐之，皿度可相同’亦可不同。於依序通過複數個乾燥爐而 進灯乾燥之情形時，較佳為以溫度自乾燥爐之前段朝向乾 燥爐之後段依序變高之方式設置溫度梯度。 [偏光板之製造] 以上述方式製造之偏光膜9可於其至少-面上貼合透明 保護膜而製成偏光板。為了將透明保護膜貼合於偏光膜， 可使用接著劑。作為透明保護膜，例如可使用如三乙酿纖 維素或二乙醯纖維素之乙酸纖維素系樹脂膜、丙稀酸系樹 •脂膜、聚I系樹脂膜、聚芳醋系樹脂膜、聚醚砜系樹脂膜、 將如降伯烯之環狀烯烴作為單體之環狀聚烯烴系樹脂膜 等。透明保護膜之厚度通常為1〇〜2〇〇 μηι左右，較佳為15'〇 μΐη以下，進而較佳為100 μιη以下。偏光板亦可於一個表 面，即保護膜之露出面上具有抗反射層或防眩層、硬塗層、 接著層等公知之各種功能性層。 156977.doc •15- 201211596 實施例 以下表示實施例及比較例，進一步具體地說明本發明， 但本發明並不受該等例限定。 於以下之實施例及比較例中，使用平均聚合度為2400、 息化度為99_9莫耳％以上且厚度為75 μηι之聚乙烯醇膜作為 原料片材膜》 又’膨潤浴、染色浴及硼酸處理浴分別共同使用下述組 成及溫度者。 膨潤浴：純水、溫度40。〇。 染色浴：碘/碘化鉀/水之重量比為0 03/5 0/100之水溶 液、溫度30°C。 硼酸處理浴：碘化鉀/硼酸/水之重量比為12/4〇/1〇〇之水 溶液、溫度56.5°C。 實施例1 . 保持膜之緊張狀態以不使聚乙烯醇原料片材膜丨鬆弛，於 此狀態下於裝有上述膨潤浴之膨潤槽3中浸潰58秒，使膜充 分地膨潤，對膜進行單軸延伸直至初始之3·49倍為止。繼 而，一面於裝有上述染色浴之染色槽4中浸潰63秒，一面以 延伸倍率約丨.2倍進行單軸延伸。其後，於裝有上述刪酸處 理浴之硼酸槽5中浸潰76秒。進而，於裝有1〇t之水之水洗 槽6中清洗約5秒，其後，花費11〇秒使其通過約7〇艽之乾燥 爐8’進行乾燥。自原料片材起之總延伸倍率為4.19倍。以 此方式獲得包含吸駭向有作為二色性色素之礙的聚乙稀 醇之偏光膜9。相對於總延伸倍率之膨潤處理中之延伸倍率 156977.doc 16 ⑧. 201211596 比為83%。 實施例2 保持膜之緊張狀態以不使聚乙烯醇原料片材膜丨鬆弛，於 此狀態下於裝有上述膨潤浴之膨潤槽3中浸潰76秒，使膜充 分地膨潤，對膜進行單軸延伸直至初始之3 55倍為止。繼 而，一面於裝有上述染色浴之染色槽4中浸潰73秒，一面以 延伸倍率約1.56倍進行單軸延伸。其後，於裝有上述硼酸 處理浴之硼酸槽5中浸潰76秒。進而，於裝有1(rc之水之水 洗槽6中清洗約5秒，其後，花費11〇秒使其通過約7〇β(：之乾 燥爐8,進行乾燥。自原料片材起之總延伸倍率為倍。 以此方式獲得包含吸附定向有作為二色性色素之碘的聚乙 烯醇之偏光膜卜相對於總延伸倍率之膨潤處理中之延伸倍 率比為64%。 比較例1 保持膜之緊張狀態以不使聚乙稀醇原料片材膜i鬆他，於 此狀態下於裝有上述膨潤浴之膨潤槽3中浸潰㈣，使膜充 分地膨潤’對膜進行單軸延伸直至初始之149倍為止。、繼 面於裝有上述染色浴之染色槽4中浸潰148秒， 面 以延伸倍率約1.71倍進行單軸延伸。其後，—面於裝有上 述硼酸處理浴之硼_5巾浸潰96秒，—輯行單料伸直 至自原料片材起之延伸倍率為5.48倍為止。進而，於裝有 阶之水之水洗槽6令清洗約5秒，其後，花費ιι〇秒使^ 過約7〇t之乾職8’㈣乾燥。以此方式獲得包含吸附定 向有作為二色性色素之峨的聚乙婦醇之偏光膜9。相對於總 156977.doc •17· 201211596 延伸倍率之膨潤處理中之延伸倍率比為27%。 比較例2 保持膜之緊張狀態以不使聚乙烯醇原料片材膜丨鬆弛，於 此狀態下於裝有上述膨潤浴之膨潤槽3中浸潰96秒，使膜充 分地膨潤，對膜進行單軸延伸直至初始之18〇倍為止。其 次，一面於裝有上述染色浴之染色槽4中浸潰114秒，一面 以延伸倍率約1.96倍進行單轴延伸。其後，一面於裝有上 述硼酸處理浴之硼酸槽5中浸潰87秒，一面進行單軸延伸直 至自原料片材起之延伸倍率為5·5〇倍為止。進而，於裝有 10 C之水之水洗槽6中清洗約5秒，其後，花費110秒使其通 過約70 C之乾燥爐8，進行乾燥。以此方式獲得包含吸附定 向有作為二色性色素之碘的聚乙烯醇之偏光膜9。相對於總 延伸倍率之膨潤處理中之延伸倍率比為33〇/〇。 [評價試驗] (a) 單體透過率之測定 使用分光光度計“V-7100”（日本分光股份有限公司製造） 測定實施例1及2以及比較例1及2中製作之各偏光膜之單體 透過率。 (b) 由加熱所致之尺寸變化之評價 將實施例1及2以及比較例1及2中製作之各偏光膜切成 100 mmxlOO mm之大小，於l〇〇°c下加熱24小時。並且，測 定試驗片之加熱前與吸收軸（即延伸方向）正交之方向TD上 之尺寸（Lb)與加熱後相同方向上之尺寸（La)，根據下式求出 TD收縮率。 156977.doc -18-⑧. 201211596 TD 收縮率=[(Lb-La)/Lb] χ 100(%) 將以上之評價試驗之結果與各例中之製造條件之主要變 數彙總於表1中。 [表1] 總延伸倍率 膨潤處理中 之延伸倍率比 染色時間 單體透過率 TD收縮率 實施例1 4.19 倍 83% 63秒 27.9% 2.60% 實施例2 5.57 倍 64% 73秒 31.6% 2.45% 比較例1 5.48 倍 27% 148秒 40.7% 3.47% 比較例2 5.50 倍 33% 114秒 38.5% 3.36% 如表1所示，可知：相對於總延伸倍率之膨潤處理中之延 伸倍率比為50%以上的實施例1及2之偏光膜之加熱後之TD 收縮率較小。又，可知：與膨潤處理中之延伸倍率比低於 5 0%之比較例1及2相比，雖然染色時間較短，但單體透過 率較低，即使於短時間内亦可高效率地進行染色。 【圖式簡單說明】 圖1係表示適於實施本發明之方法的裝置之配置例之模 式圖。 【主要元件符號說明】 1 原料片材膜 2 原料片材輥 3 膨潤槽 4 染色層 5 硼酸槽 6 水洗槽 8 乾燥爐 156977.doc -19- 201211596 偏光膜 夾送輥 夾送輥 夾送輥 夾送輥 夾送輥 夾送輥 9 31 32 41 42 51 52 156977.docTransverse Direction) shrinks. Ρ ί ί ί ί ί ί ί ί ί ί ί ί ί ί ί ί ί ί ί ί ί ί ί ί ί : : : : : : : 为了 为了 为了 为了 为了 为了 为了 为了 为了 为了 为了 为了 为了 ' ' ' ' ' ' ' ' ' ' The stretching treatment was performed 4 times, and thereafter, a dyeing treatment and a crosslinking treatment using a dichroic dye were carried out to produce a polarizing film. In Example 1 of the document, the stretching ratio was twice as long as that in the swelling bath, and then the stretching was performed in the eucalyptus dye bath and the boric acid treatment bath, respectively, and finally set to a total stretching ratio of 6.5 times. In the swell bath, the stretching ratio was 2.5 times, and then the stretching treatment was carried out in the color bath and the boric acid treatment bath, and finally the total stretching ratio was 6 times. Although the method disclosed in this document is effective for suppressing dyeing unevenness, it is known from experiments by the exemplified person and the like that if the stretching is carried out only in the swelling bath at the magnification shown in the examples, the resulting polarizing film is obtained. The shrinkage is still large when exposed to high temperature conditions. On the other hand, (4) (4) Weng Yizhong records that the polyethyl alcohol-based phase lipid film is continuously treated in a bath of swelling treatment, dyeing treatment and (iv) treatment, and at least one step in the feed. When uniaxially stretching to produce a polarizing film, a thirst step is set between the swelling treatment and the dyeing treatment, and (4) is used to obtain a reading solution, and the aqueous solution is more than 1. times and less than 3 times in 1 aqueous solution. The stretching ratio is uniaxially extended to achieve advancement of color unevenness. Further, (4) Team 249766_A 156977.doc 201211596 There is a case where a wet stretching step of uniaxial stretching is performed at a stretching ratio of 1.1 times or more between the swelling treatment and the dyeing treatment as disclosed in JP2005-U4990-A. In the case where the width of the obtained long polarizing film is likely to be uneven toward the central portion and the end portion, a water immersion treatment step is provided between the swelling treatment and the dyeing treatment, and the stretching ratio here is 1.05 times. the following. As described above, if the polarizing film manufactured by the swelling treatment, the dyeing treatment, the boric acid treatment, and the drying treatment is exposed to a high temperature condition, it shrinks not only in the absorption direction (MD) but also in the direction orthogonal to the absorption axis ( TD) shrinks. Further, in the method for producing a polarizing film previously used, it is difficult to suppress such shrinkage, particularly shrinkage in a direction orthogonal to the absorption axis. Therefore, an object of the present invention is to provide a method for producing a polarizing film which is excellent in shrinkage ratio when the polarizing film is exposed to high temperature conditions, particularly in a direction orthogonal to the absorption axis, and which is excellent in dyeability. . SUMMARY OF THE INVENTION That is, the present invention includes the following. [1] A method for producing a polarizing film, which comprises: sequentially performing a swelling treatment of a polyethylene glycol alcohol tree sapstock raw material sheet film through a swelling tank, a dyeing treatment through a dyeing tank, and a boric acid passing through a boric acid tank. Processing, and performing uniaxial stretching in at least one of dyeing treatment and acid removal treatment; the swelling treatment is performed on a side of the uniaxially stretched surface of the polyvinyl alcohol-based resin raw material sheet film The ratio of the single-stretching extension is 5% to 156,977.doc. 6.9977.doc. The manufacturing method of the polarizing film as π] from the raw material sheet film to the polarizing film is obtained. The treatment is carried out at the temperature of the heart thief. (1) If the film is produced in a polarized form as in (1) or [2], the towel is treated in pure water having substantially no dissolved component. [4] A method for producing a polarizing plate, which comprises producing a polarizing film by the method according to any one of (1) to (1), and bonding a protective film to the surface or both surfaces of the obtained polarizing film. According to the method of the present invention, a polarizing film having high dyeing efficiency and low absorption in the direction orthogonal to the absorption axis can be produced. [Embodiment] Hereinafter, the present invention will be described in detail. In the present invention, the polyvinyl alcohol-based resin raw material sheet film is continuously subjected to swelling treatment through a swelling tank, dyeing treatment by a dyeing tank, and boric acid treatment by a boric acid tank, and in dyeing treatment and boric acid treatment. A polarizing film is produced by performing uniaxial stretching in at least one process. In terms of the relationship of continuous treatment in this manner, the polyvinyl alcohol-based resin raw material sheet film is usually supplied in the form of a roll. In the figure, a configuration example of a device which is not suitable for carrying out the method for producing a polarizing film of the present invention is shown. In the example shown in FIG. 1, the polyvinyl alcohol-based resin raw material sheet film 1 taken out from the raw material sheet roll 2 is sequentially passed through a swelling tank 3 for performing a swelling treatment, and a dyeing residue for dyeing treatment. And the polyvinyl alcohol-based resin film which is used for the boric acid treatment in the boric acid tank at 5 ° from the acid removal tank 5 is usually washed away from the unreacted boric acid aqueous solution adhered to the previous tank by the water washing tank 6', and thereafter' The drying film 8 is dried to obtain a polarizing film 9. Although the illustration 156977.doc 201211596 is omitted, the transparent protective film is usually adhered to at least the surface of the obtained polarizing film to form a polarizing plate. Further, in the present invention, when the polarizing film is produced by the above respective processes, the swelling treatment performed by the expansion of the film 3 is performed while the raw material sheet film 1 is uniaxially stretched, and the swelling treatment is performed. The ratio of the stretching ratio to the total stretching ratio from the raw material sheet film 1 to the polarizing film 9 is 5 G% or more. In the swelling treatment, a liquid having water as a main component is used as a swelling bath. Thus, the method for producing a polarizing film of the present invention preferably comprises the following steps (1) to (6)? (The polyvinyl alcohol-based resin raw material sheet film 1 is passed through a swelling bath containing water as a main component. a swelling treatment step of swelling the tank 3 in contact with the swelling bath; (2) passing the swollen polyvinyl alcohol resin film through the dyeing tank 4' containing the dye bath containing the dichroic dye in the dye bath a dyeing treatment step in which dyeing is carried out; (3) a boric acid treatment step of crosslinking the dyed polyvinyl alcohol-based resin film through a boric acid tank 5 containing an aqueous solution containing boric acid; (4) a polyvinyl alcohol-based resin a step of extending the uniaxial stretching of the resin film; (5) a step of washing the boric acid-treated polyvinyl alcohol-based resin film through a washing tank 6 for washing with a solution containing water as a main component; and (6) The drying step of the drying furnace 8 after the water washing treatment. The polyvinyl alcohol-based resin film to be a raw material sheet and the above respective steps will be described in detail in the following. 156977.doc . 8 - 8 201211596 [Polyvinyl alcohol resin raw material Sheet film The polyvinyl alcohol-based resin which is a polarizing film is obtained by saponifying a polyvinyl acetate-based resin. The polyvinyl acetate-based resin may be vinyl acetate in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. A copolymer of an ester and another monomer copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, and the like. The degree of saponification of the vinyl alcohol resin is usually from about 85 to 100 mol%, preferably from 98 to 100 mol%, and the polyvinyl alcohol resin may be further modified, for example, a modification by an aldehyde may also be used. Further, the degree of polymerization of the polyvinyl alcohol-based resin is usually about 1 Torr to about 1 Torr, preferably from 1,500 to 5,000. The polyvinyl alcohol-based resin is used. The film-forming film is used as a raw material sheet film of a polarizing film. The method of forming a film of a polyvinyl alcohol-based resin is not particularly limited, and a film can be formed by a method known in A. The film thickness of the polyvinyl alcohol-based resin raw material sheet film is No special limit 'for example, 2〇~1 The raw material sheet film is usually supplied in a money form as described above, and its practical width is in the range of about 1500 to 6000 mm. [Swelling treatment step] First, the raw material sheet is placed in the swelling tank 3. The film 1 is subjected to a swelling treatment, which is carried out in order to remove foreign matter on the surface of the film, remove the plasticizer present in the film, impart dyeability to the next step, and plasticize the film. The swelling treatment step swells the raw material sheet film 1 in the swelling bath in the swelling tank 3, and the surface is uniaxially stretched 156977.doc 201211596: and the 'in the swelling treatment step The ratio of the stretching ratio to the total stretching ratio from the original to the time when the polarizing film 9 is obtained becomes. In the present invention, the ratio of the magnification to the total magnification of the film from the raw material sheet to the polarizing film 9 is referred to as "the stretching ratio in the swelling treatment". "." The stretching ratio of the swelling property t is preferably 6 G% or more. By increasing the stretching ratio of the swelling treatment, the dichroic dye 2 is easily oriented in the lower-dyeing step, and the dyeing can be performed efficiently. Further, when the obtained polarized light is exposed to the south temperature condition, the shrinkage ratio in the direction orthogonal to the absorption axis can be suppressed low. In the present specification, the shrinkage ratio in the direction orthogonal to the absorption axis of the polarizing film is sometimes referred to as "the TD shrinkage ratio when the polarizing film is exposed to a high temperature condition, and the TD shrinkage ratio is suppressed low. It is said that although it is advantageous to increase the stretching ratio in the swelling treatment, in another aspect, in the present invention, since the uniaxial stretching is performed in at least one of the subsequent dyeing treatment step and the butterfly acid treatment step, Therefore, the upper limit of the stretching ratio in the swelling treatment is usually up to the point of swelling. The swelling treatment step is performed by swelling the raw material sheet film through a swelling bath which is usually maintained at a temperature of about 2 〇 5 〇〇 5 〇〇. The uniaxial extension can be performed by the difference in circumferential speed between the inlet side pinch roller 31 and the outlet side pinch roller 32 of the swelling tank 3. The swelling treatment time also includes a uniaxial extension. , usually 2 to 3 seconds, preferably 40 to 240 seconds. The swelling bath used in the swelling tank 3 may be added to the above range of the weight % of the 〇〇ι~ι〇 in addition to the pure water. Recorded in JpH1〇_1537〇9 A Boron 156977.doc 8 -10 - 201211596 ι, an aqueous solution of a mineral salt represented by a chloride, a water-soluble organic solvent represented by an alcohol, etc., wherein the use of the swelling tank 3 is preferably Pure water without dissolved components. In the case of the lake treatment step, when the film is swollen in the width direction and the film is wrinkled, the expansion roll, the spiral roll, the middle and high roll, the = report, A well-known expansion device such as a f-roller or a tenter clip--a surface-removing film-sensitive surface-transporting film. In order to stabilize the film transport in the bath, the water jet in the swell bath is controlled by an underwater sprinkler' or EPC is used in combination. The device (Edge Position C〇ntroller) is also useful for detecting the end of the film and preventing the film from being twisted. [Staining process step] (4) The post-treated polyvinyl alcohol-based tree film is delivered to a dyeing treatment step through a dyeing tank 4 containing a dye bath containing a dichroic dye. The dichroic dye is usually a dye or a dichroic organic dye. Treatment system in order to make dichroic pigment adsorption It is carried out in the form of a polyethylene glycol-based resin film, and the conditions are within the range in which such a purpose can be achieved, and are determined within a range in which the film does not cause extreme dissolution or devitrification, etc. In the case of a pigment, it is preferred to use (4) an aqueous solution containing hydrazine as a dyeing. In this case, for example, by 1c, preferably at a temperature of 2 〇 to a thief, and at a weight relative to water (10) For the portion containing Wei 003~〇.2 parts by weight and Wei_q^q parts by weight, dipping for 10~600 seconds, preferably 3〇~2〇〇 seconds, for dyeing at 156977.doc 201211596. Other iodides such as iodide may be used instead of potassium iodide, and other iodides may be used in combination with potassium iodide. In the dye bath, compounds other than iodide, such as boric acid, chlorinated, cobaltated cobalt, and the like may be present. Further, even in the case where boric acid is added, the treatment bath contains iodine, and can be distinguished from the subsequent boric acid treatment. As long as it is a bath containing 0.003 parts by weight or more with respect to 1 part by weight of water, it can be regarded as a dyed heart valley. From the viewpoint of imparting higher polarization performance to the obtained polarizing film, it is preferred to use iodine as a coloring dye. On the other hand, when a water-soluble dichroic dye is used as the dichroic dye, for example, it is contained at a temperature of 20 to 80 ° C, preferably 30 °, and it is contained in 100 parts by weight with respect to water. The aqueous solution of the dichroic dye 〇〇〇1 to 〇丨 parts by weight is used as a dyeing bath, and is subjected to a dyeing treatment by immersing therein for 1 〇 6 6 sec, preferably 2 〇 to 3 〇〇 seconds. The aqueous solution of the dichroic dye to be used may further contain a dyeing assistant or the like, and for example, may contain an inorganic salt such as sodium sulfate or a surfactant. "The dichroic dye may be used alone or in combination with the desired hue. More than one dichroic dye. Even in the dyeing treatment step, the expansion roll 'screw roll, medium-high roll, guide roll, bending roll, and the like can be appropriately set in the dye bath application and/or the dye bath inlet and outlet as in the case of the swelling treatment step. Further, in the dyeing step, the film may be uniaxially stretched in the machine direction (MD) at the same time. When the uniaxial stretching is carried out in the dyeing treatment step, it is preferred that the stretching ratio is, for example, in the range of 1.1 to 3 times. When the uniaxial stretching is performed in the dyeing step, it is still possible to set a difference in the peripheral speed between the inlet side pinch roller 41 and the outlet side pinch member 42 in the dyeing tank 4. 156977.doc 8 •12- 201211596 [Baconic acid treatment step] The dyed polyethylene resin film is delivered to the boric acid treatment step in the acid removal tank 5. This boric acid treatment is carried out by immersing a polyethylene glycol-based resin film dyed with a dichroic dye in an aqueous solution of phthalic acid in the caustic acid tank 5. The content of boric acid in the aqueous boric acid solution is usually from about 2 to 15 parts by weight, preferably from 3 to 12 parts by weight, per part by weight of water. In the case of the previous dyeing treatment, when the user is used as a dichroic dye, the boric acid aqueous solution preferably contains potassium telluride. When the boric acid aqueous solution contains a moth clock, the amount of potassium iodide is 100 parts by weight. The water is usually 4 parts by weight or less, preferably 30 parts by weight or less. Further, the potassium iodide is preferably contained in an amount of 0.1 part by weight or more per 1 part by weight of the water, and more preferably 1 part by weight or more. The immersion time in the aqueous boric acid solution is usually from about 6 Torr to about 1,2 sec., preferably from 60 to 600 sec, and more preferably from 60 to 400 sec. The temperature of the aqueous solution containing boric acid is usually 50 ° C or higher, preferably 50 to 85 ° C, more preferably 55 to 80 ° C. Even in the boric acid treatment step, the film can be simultaneously uniaxially stretched in the machine direction (MD) in the treatment bath. In the case where the uniaxial stretching is carried out in the boric acid treatment step, it is still possible to carry out the difference in circumferential speed between the inlet side pinch roller 51 and the outlet side pinch roller 52 in the boric acid tank 5. [Extension processing step] In the production method of the present invention, the uniaxial stretching of the polyvinyl alcohol-based resin film is performed in at least one of the dyeing treatment step and the boric acid boat step, and further, the swelling may be performed. In the processing step. Further, the ratio of the stretching ratio in the swelling treatment step to the total stretching ratio from the raw material sheet film to 156977.doc 13 201211596 to obtain the polarizing film 9 is the ratio of the stretching ratio in the swelling treatment defined above. above 50. In this manner, uniaxial stretching is performed in at least one of the dyeing treatment step and the boric acid treatment step, and even if the bicycle is extended in the swelling treatment step, the stretching ratio in the swelling treatment is 50% or more. The uniaxial stretching treatment of the polyvinyl alcohol-based resin film may be carried out before the swelling treatment step, or may be performed between the swelling treatment step and the dyeing treatment step, the dyeing treatment step, and the acid-acid treatment step. In general, however, it is preferred to carry out the uniaxial stretching as described above in the swelling treatment step, and to perform uniaxial stretching in one or both of the dyeing treatment step and the acid-acid treatment step. The stretching in the swelling treatment step, the dyeing treatment step, and the boric acid treatment step is carried out by stretching in a state in which the respective treatment baths are swollen, i.e., wet stretching. In the present invention, as described above, 'substantially in at least one of the dyeing treatment step and the boric acid treatment step, and the swelling treatment step are carried out, so it is preferred to carry out all extension in a wet manner. Wet uniaxial stretching is generally carried out by passing it through rolls having different circumferential speeds. [Washing Treatment Step] After the boric acid treatment step, a water washing treatment is usually carried out in the water washing tank 6. The water washing treatment can be carried out, for example, by a method of impregnating a boric acid-treated polyvinyl alcohol-based resin film in water, a method of spraying water by a water sprayer, a method of impregnating and spraying, and the like. The temperature of the water in the water washing treatment is usually 2 to 40 ° C, and the treatment time is usually 2 to 120 seconds. The washing treatment can be carried out in stages or in multiple stages. In the case of multi-stage water washing treatment, it can be handled at 156977.doc 8 -14· 201211596. The inorganic salt produced in this case may, for example, be potassium, sodium iodide, zinc sulphide, chlorinated, sodium sulphate or sodium sulfite. These inorganic salts may be used in the form of a plurality of species, or may be extended in a washing tank, for example, may be extended to about 1.05 to 1.2 times. [Drying Step] Usually, the film after the water washing treatment is introduced into the drying furnace 8 to carry out a drying treatment. The drying is carried out by a drying oven 8 which is maintained at a temperature of 4 Torr to 1 Torr, preferably 50 to 10 (the temperature of TC is about 3 Torr to _ second. The drying furnace 8 can be plural In the case of setting a plurality of drying ovens, the degrees of the drying ovens may be the same 'may be different. In the case of sequentially drying through a plurality of drying furnaces, it is preferred to use a temperature self-drying furnace. The temperature gradient is set so that the subsequent stage becomes higher toward the drying furnace. [Production of Polarizing Plate] The polarizing film 9 manufactured in the above manner can be bonded to the at least one surface to form a polarizing plate. A transparent protective film may be bonded to the polarizing film, and an adhesive may be used. As the transparent protective film, for example, a cellulose acetate resin film such as triethyl cellulose or diethyl cellulose, or an acrylic acid resin may be used. a film, a poly-I-based resin film, a polyaryl vinegar-based resin film, a polyether sulfone-based resin film, a cyclic polyolefin-based resin film containing a cyclic olefin such as a primary olefin, or the like. The thickness of the transparent protective film is usually It is about 1〇~2〇〇μηι, preferably 15'〇μΐ Further, it is preferably 100 μm or less. The polarizing plate may have a known functional layer such as an antireflection layer or an antiglare layer, a hard coat layer, and a subsequent layer on one surface, that is, the exposed surface of the protective film. Doc • 15 - 201211596 EXAMPLES Hereinafter, the present invention will be specifically described by way of examples and comparative examples, but the present invention is not limited by the examples. In the following examples and comparative examples, the average degree of polymerization was 2,400. A polyvinyl alcohol film having a degree of recombination of 99_9 mol% or more and a thickness of 75 μm is used as a raw material sheet film. Further, the following composition and temperature are used together for the swelling bath, the dye bath, and the boric acid treatment bath. Water, temperature 40. 染色 Dyeing bath: iodine / potassium iodide / water weight ratio of 0 03/5 0 / 100 of aqueous solution, temperature 30 ° C. Boric acid treatment bath: potassium iodide / boric acid / water weight ratio of 12 / 4 An aqueous solution of 〇/1〇〇, a temperature of 56.5 ° C. Example 1. Maintaining the tension of the film so as not to relax the film of the polyvinyl alcohol raw material sheet, in this state in the swelling tank 3 containing the above-mentioned swelling bath Dip for 58 seconds to make the film full The film was uniaxially stretched until it was 3-4 times as large as the initial one. Then, it was immersed for 63 seconds in the dyeing bath 4 containing the dye bath, and uniaxially stretched at a stretching ratio of about 倍. Thereafter, it was immersed in a boric acid tank 5 containing the above-described acid-cutting treatment bath for 76 seconds, and further washed in a water washing tank 6 containing 1 Torr of water for about 5 seconds, and then it took 11 seconds to make it Drying is carried out by a drying oven 8' of about 7 inches. The total stretching ratio from the raw material sheet is 4.19 times. In this way, a polarizing film comprising a polyethylene glycol having a function as a dichroic dye is obtained. 9. The stretching ratio in the swelling treatment with respect to the total stretching ratio is 156977.doc 16 8. The ratio of 201211596 is 83%. Example 2 The film was kept in a state of tension so as not to relax the film of the polyvinyl alcohol raw material sheet, and in this state, it was immersed in the swelling tank 3 containing the above-mentioned swelling bath for 76 seconds to sufficiently swell the film, and the film was subjected to a film. Uniaxial extension until the initial 3 55 times. Then, uniaxial stretching was performed at a stretching ratio of about 1.56 times while being dipped in the dyeing bath 4 equipped with the above dye bath for 73 seconds. Thereafter, it was immersed in a boric acid tank 5 containing the above-described boric acid treatment bath for 76 seconds. Further, it is washed in a water washing tank 6 containing 1 (r of water) for about 5 seconds, and then it takes 11 seconds to pass it through a drying oven 8 of about 7 〇β (drying. From the raw material sheet) The total stretching ratio was a multiple. In this manner, a polarizing film containing a polyvinyl alcohol adsorbed with iodine as a dichroic dye was obtained, and the stretching ratio in the swelling treatment with respect to the total stretching ratio was 64%. Comparative Example 1 The tension state of the film is such that the film of the polyethylene raw material sheet is not loosened, and in this state, it is immersed in the swelling tank 3 containing the above-mentioned swelling bath (4), and the film is sufficiently swollen to perform uniaxial stretching on the film. Up to 149 times of the initial period, immersed in the dyeing tank 4 containing the dye bath for 148 seconds, and the surface was uniaxially stretched at a stretching ratio of about 1.71 times. Thereafter, the surface was filled with the boric acid treatment bath. The boron _5 towel is immersed for 96 seconds, and the single material is stretched until the stretching ratio from the raw material sheet is 5.48 times. Further, the washing is performed in the water washing tank 6 with the step water for about 5 seconds. After that, it takes ιι 〇 秒 to make it dry for about 8 〇t (8) dry. The polarizing film 9 of polyephedrine alcohol which is a bismuth pigment is oriented. The stretching ratio ratio in the swelling treatment of the total magnification of 156977.doc •17·201211596 is 27%. Comparative Example 2 Maintaining the tension of the film In the state, the film of the polyvinyl alcohol raw material sheet was not slackened, and in this state, it was immersed in the swelling tank 3 containing the above-mentioned swelling bath for 96 seconds to sufficiently swell the film, and the film was uniaxially stretched until the initial 18 Next, the uniaxial stretching is performed at a stretching ratio of about 1.96 times while being immersed in the dyeing tank 4 containing the dyeing bath for 114 seconds. Thereafter, the boric acid tank 5 containing the boric acid treatment bath is placed on one side. After immersing for 87 seconds, the uniaxial stretching was performed until the stretching ratio from the raw material sheet was 5·5 〇. Further, it was washed in a washing tank 6 containing 10 C of water for about 5 seconds, and thereafter, It takes 110 seconds to pass through a drying oven 8 of about 70 C, and is dried. In this way, a polarizing film 9 containing polyvinyl alcohol adsorbed with iodine as a dichroic dye is obtained. In the swelling treatment with respect to the total stretching ratio The stretch ratio ratio is 33 〇 / 〇. Valence test] (a) Measurement of monomer transmittance The monomers of the respective polarizing films produced in Examples 1 and 2 and Comparative Examples 1 and 2 were measured using a spectrophotometer "V-7100" (manufactured by JASCO Corporation). Transmittance (b) Evaluation of dimensional change by heating The polarizing films produced in Examples 1 and 2 and Comparative Examples 1 and 2 were cut into a size of 100 mm x 100 mm, and heated at 10 ° C. In addition, the dimension (Lb) in the direction TD orthogonal to the absorption axis (i.e., the direction of extension) before the heating of the test piece and the dimension (La) in the same direction after heating were measured, and the TD shrinkage ratio was obtained from the following equation. 156977.doc -18-8. 201211596 TD shrinkage = [(Lb-La) / Lb] χ 100 (%) The main variables of the above evaluation test results and the manufacturing conditions in each case are summarized in Table 1. [Table 1] Total Stretch Ratio Stretching Ratio in Swelling Treatment Ratio Dyeing Time Monomer Transmittance TD Shrinkage Example 1 4.19 times 83% 63 seconds 27.9% 2.60% Example 2 5.57 times 64% 73 seconds 31.6% 2.45% Comparison Example 1 5.48 times 27% 148 seconds 40.7% 3.47% Comparative Example 2 5.50 times 33% 114 seconds 38.5% 3.36% As shown in Table 1, it is understood that the stretching ratio ratio in the swelling treatment with respect to the total stretching ratio is 50% or more. The polarizing films of Examples 1 and 2 had a small TD shrinkage after heating. Further, it can be seen that the dyeing time is shorter than that of Comparative Examples 1 and 2 in which the stretching ratio ratio in the swelling treatment is less than 50%, but the monomer transmittance is low, and the efficiency can be efficiently performed even in a short period of time. Dyeing. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing an arrangement example of a device suitable for carrying out the method of the present invention. [Main component symbol description] 1 Raw material sheet film 2 Raw material sheet roll 3 Expansion tank 4 Dye layer 5 Boric acid tank 6 Washing tank 8 Drying furnace 156977.doc -19- 201211596 Polarizing film pinch roll pinch roll pinch roll clamp Feed roller pinch roller pinch roller 9 31 32 41 42 51 52 156977.doc