1359286 (1) 九 '發明說明 【發明所屬之技術領域】 本發明係關於一種表面狀態良好、不均句染色 光薄膜之製造方法，使用該偏光薄膜的偏光板之 法’以及光學層合物之製造方法。 【先前技術】 傳統作爲偏光薄膜，係使用二向色性（dichr( 素吸附配向於聚乙烯醇系薄膜者。亦即，已知碘作 色性色素之碘系偏光薄膜、二向色性染料作爲二向 素之染料系偏光薄膜等。這些偏光薄膜通常至少一 佳爲兩面隔著聚乙烯醇系樹脂的水溶液構成的接著 附三乙醯基纖維素等的保護薄膜，成爲偏光板。 作爲偏光薄膜的製造方法，於專利文獻1中記 乙烯醇系薄膜浸漬於碘以及碘化鉀的水溶液後’將 且以硼酸處理，水洗後再浸漬於碘以及碘化鉀的水 然後乾燥之方法。 於專利文獻2中，記載將延伸的薄膜浸漬於含 色性色素的水溶液，再浸漬於其他的含有二向色性 水溶液後《於硼酸水溶液中延伸，然後乾燥，製造 附配向層設置於厚度方向之偏光薄膜。 於專利文獻3中，記載將延伸的聚乙烯醇系薄 於特定的二向色性染料水溶液（染色液A)後，浸 以及碘化鉀的水溶液（染色液B )，然後以硼酸處 少的偏 .'ifc -t 衣；ΙΞ力 )ic )色 爲二向 色性色 面，較 劑，貼 載將聚 其延伸 溶液， 有二向 色素的 2個吸 膜浸漬 漬於碘 理、水 -5- (2) (2)1359286 洗，製造偏光薄膜之方法》 於專利文獻4中’記載將聚乙烯醇薄膜浸漬於含有 碘、碘化鉀、硼酸之水溶液’染色然後進行一軸延伸後， 以硼酸處理，製造偏光薄膜之方法。 但是’進行2次染色處理的專利文獻1〜3，表面狀態 差，無法得到鏡面反射’有外觀差的問題。另一方面，含 硼酸的染色浴進行染色之專利文獻4的方法，有染色不均 (mura)的問題。 〔專利文獻1〕日本公開專利特開平9-133809號公報 〔專利文獻2〕日本公開專利特開昭60-66205號公報 〔專利文獻3〕日本公開專利特開昭62-70802號公報 〔專利文獻4〕日本公開專利特公平3-23881號公報 的實施例 【發明內容】 〔發明所欲解決之課題〕 本發明的主要課題’在於提供表面狀態良好、不均勻 染色少的偏光薄膜之製造方法，使用該偏光薄膜的偏光板 之製造方法，以及光學層合物之製造方法。 〔解決課題之手段〕 本發明人等’爲解決上述課題反覆專心檢討的結果， 發現硼酸處理前利用2段以上的染色浴依序進行碘染色， 最後的染色浴包含硼酸的情況，可得表面狀態良好、不均 -6- (3) (3)1359286 勻染色少的偏光薄膜，而完成本發明。 亦即，關於本發明的偏光薄膜之製造方法，係聚乙烯 醇系薄膜依序進行膨脹處理、染色處理以及硼酸處理之處 理步驟前以及/或處理步驟中進行一軸延伸，其特徵爲： 在硼酸處理步驟前設置2段以上的染色浴，依序進行染 色，而且最後的染色浴含有硼酸。 上述最後的染色浴中硼酸的濃度係由如以下方式決 定。亦即，最後的染色浴中每100重量份的水，硼酸的含 量爲a重量份，且上述聚乙烯醇系薄膜從原結構（未延伸 薄膜）至離開上述最後的染色浴爲止的總延伸倍率爲b 時.，上述a以及b滿足下述關係式。 b<-0.5lxa+3.77 最後的染色浴中通常每100重量份的水，硼酸的含量 約0.05〜2.0重量份較佳。而且，2段以上的染色浴的溫度 可約 1 0 ~ 4 0 °C。 關於本發明的偏光板之製造方法，其特徵爲上述方法 得到的偏光薄膜，至少一面貼合保護薄膜。保護薄膜具備 相位差薄膜、增亮薄膜、改良視角薄膜以及半透過反射薄 膜中任一功能較佳。 關於本發明的光學層合物之製造方法，其特徵爲上述 方法得到的偏光板，與至少1種選自相位差薄膜、增亮薄 膜、改良視角薄膜以及半透過反射薄膜所成群的薄膜貼 (4) (4)1359286 合 〔發明的效果〕 根據本發明，因爲以2段以上的染色洛依序進行染 色’可減少偏光薄膜的染色不均，且藉由最後的染色浴含 有硼酸，在硼酸處理步驟可抑制薄膜表面狀態的惡化，有 提高光學特性的效果。 【實施方式】 以下，詳細說明本發明。 形成本發明的聚乙烯醇系薄膜之聚乙烯醇系樹脂，通 常爲例如聚乙酸乙烯酯系樹脂皂化之物質。皂化度通常約 8 5莫耳％以上’較佳約爲9 〇莫耳％以上，更好約爲9 9莫 耳％〜1 00莫耳％。作爲聚乙酸乙烯酯系樹脂，除乙酸乙燦 醋爲卓聚合物之聚乙酸乙烧醋外，乙酸乙稀醋以及可與其 共聚合之其他單量體的共聚合物，例如乙嫌-乙酸乙烧醋 共聚合物等。作爲可與其共聚合之其他單量體，例如不飽 和羧酸類' 烯烴類、乙烯醚類、不飽和磺酸類等。聚乙烯 醇系樹脂的聚合度爲1000〜1〇〇〇〇，較佳爲15〇〇〜5000的 程度。 這些聚乙烯醇系樹脂也可爲變性而得，例如可使用醛 類變性之聚乙烯縮甲醛 '聚乙烯縮乙醛、聚乙烯縮丁醛 等。通常製造偏光薄膜的起始材料，使用厚度約 20μιη〜ΙΟΟμιη、較佳爲3〇pm〜80μπι的聚乙烯醇系樹脂薄膜 13592861359286 (1) Nineth Invention [Technical Field] The present invention relates to a method for producing a film having a good surface condition, a non-uniform sentence dyeing light film, a method of using a polarizing film of the polarizing film, and an optical laminate Production method. [Prior Art] Conventionally, as a polarizing film, dichroism (dichr is applied to a polyvinyl alcohol-based film, that is, an iodine-based polarizing film or a dichroic dye known as an iodine-based coloring matter) is known. A dichroic dye-based polarizing film, etc. These polarizing films are usually at least one protective film made of an aqueous solution of a polyvinyl alcohol-based resin on both sides, followed by a protective film such as triethyl fluorenyl cellulose to form a polarizing plate. In the method of producing a film, Patent Document 1 discloses a method in which a vinyl alcohol-based film is immersed in an aqueous solution of iodine and potassium iodide, treated with boric acid, washed with water, and then immersed in water of iodine and potassium iodide, and then dried. It is described that the stretched film is immersed in an aqueous solution containing a coloring dye, and after being immersed in another aqueous solution containing a dichroic solution, it is stretched in an aqueous solution of boric acid, and then dried to produce a polarizing film in which the adhesion layer is provided in the thickness direction. Patent Document 3 describes that the stretched polyvinyl alcohol is thinner than a specific dichroic dye aqueous solution (dyeing solution A), and then immersed and An aqueous solution of potassium iodide (dyeing solution B), and then a small amount of boric acid, 'ifc-t clothing; ΙΞ) ic ) color is a dichroic color surface, compared with the agent, the loading will be concentrated in the extended solution, there are two A method of producing a polarizing film by immersing the two absorbing membranes of the dye in iodide and water-5-(2) (2) 1359286, and describing that the polyvinyl alcohol film is impregnated with iodine or potassium iodide. A method of producing a polarizing film by dyeing an aqueous solution of boric acid and then performing one-axis stretching and then treating with boric acid. However, in Patent Documents 1 to 3 in which the dyeing treatment was performed twice, the surface state was poor, and specular reflection was not obtained, which had a problem of poor appearance. On the other hand, the method of Patent Document 4 in which a dye bath containing boric acid is dyed has a problem of uneven dyeing (mura). [Patent Document 1] Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. [Embodiment of the Invention] [Problem to be Solved by the Invention] The main subject of the present invention is to provide a method for producing a polarizing film having a good surface condition and less uneven dyeing. A method for producing a polarizing plate using the polarizing film, and a method for producing an optical layer. [Means for Solving the Problem] The inventors of the present invention found that the surface of the dye bath was iodine-dyed in two stages or more before the boric acid treatment, and the final dye bath contained boric acid. The present invention has been completed in a state in which the polarizing film having a small degree of dyeing is inferior in the state of -6-(3) (3) 1359286. That is, in the method for producing a polarizing film of the present invention, the polyvinyl alcohol-based film is subjected to one-axis stretching before and/or in the treatment step of the expansion treatment, the dyeing treatment, and the boric acid treatment, and is characterized by: Before the treatment step, two or more dye baths were set, followed by dyeing, and the final dye bath contained boric acid. The concentration of boric acid in the above dye bath is determined as follows. That is, the content of boric acid is a part by weight per 100 parts by weight of water in the final dyeing bath, and the total stretching ratio of the above polyvinyl alcohol-based film from the original structure (unstretched film) to leaving the last dye bath. When b is , the above a and b satisfy the following relational expression. b<-0.5lxa+3.77 In the final dyeing bath, the content of boric acid is preferably from 0.05 to 2.0 parts by weight per 100 parts by weight of water. Further, the temperature of the dye bath of two or more stages may be about 10 to 40 °C. In the method for producing a polarizing plate of the present invention, the polarizing film obtained by the above method is bonded to at least one surface of the protective film. The protective film is preferably provided with any one of a retardation film, a brightness enhancement film, a modified viewing angle film, and a semi-transmissive reflection film. The method for producing an optical layered composition of the present invention is characterized in that the polarizing plate obtained by the above method is bonded to at least one film selected from the group consisting of a retardation film, a brightness enhancement film, a modified viewing angle film, and a semi-transmissive reflection film. (4) (4) 1359286 [Effects of the Invention] According to the present invention, dyeing by dyeing in two or more stages can reduce the uneven dyeing of the polarizing film, and the boric acid is contained in the final dye bath. The boric acid treatment step suppresses deterioration of the surface state of the film and has an effect of improving optical characteristics. [Embodiment] Hereinafter, the present invention will be described in detail. The polyvinyl alcohol-based resin which forms the polyvinyl alcohol-based film of the present invention is usually a material which is saponified by, for example, a polyvinyl acetate-based resin. The degree of saponification is usually about 8 5 mol% or more, preferably about 9 〇 mol% or more, more preferably about 9 9 mol% to 1 00 mol%. As a polyvinyl acetate-based resin, in addition to acetic acid ethyl vinegar as a polymer of polyethylene acetate vinegar, ethyl acetate vinegar and other mono-compound copolymers copolymerizable therewith, such as B-acetic acid B Burning vinegar copolymer, etc. As the other monomer which can be copolymerized therewith, for example, unsaturated carboxylic acids 'olefins, vinyl ethers, unsaturated sulfonic acids and the like. The degree of polymerization of the polyvinyl alcohol-based resin is from 1,000 to 1 Torr, preferably from 15 Å to 5,000. These polyvinyl alcohol-based resins may be obtained by denaturation. For example, an aldehyde-modified polyvinyl formal, 'polyvinyl acetal, polyvinyl butyral, or the like can be used. A starting material for a polarizing film is usually produced, and a polyvinyl alcohol-based resin film having a thickness of about 20 μm to ΙΟΟμηη, preferably 3 μm to 80 μm is used.
之未延伸薄膜。工業上，薄膜的寬度實用上約爲 1 500mm〜4〇〇〇mm » 該未延伸薄膜依序進行膨脹處理、染色處理' 硼酸處 理、水洗處理’最後乾燥得到聚乙烯醇系偏光薄膜的厚 度，例如約5〜5 0 μ m的程度。 本發明的偏光薄膜’係吸附配向二向色性色素之聚乙 烯醇系一軸延伸薄膜’其製作方法，大致分爲2種製造方 法’弟—爲聚乙烧醇系薄膜在空氣或不活性氣體中—軸延 伸後’依序進行膨脹處理、染色處理、硼酸處理、水洗處 理之溶液處理’最後進行乾燥的方法。第二爲未延伸的聚 乙嫌醇系薄膜’於水溶液依序進行膨脹處理、染色處理' 硼酸處理、水洗處理之溶液處理，在硼酸處理步驟以及/ 或其前一步驟’溼式下進行一軸延伸，最後進行乾燥的方 法。 在任一種方法’一軸延伸可以由一個步驟進行，也可 由2個以上的步驟進行，由複數的步驟進行較佳。延伸方 法’可採用習知的方法，例如傳送薄膜的2個夾輪間賦予 轉速差進行延伸之滾輪間延伸，如日本專利第2 73 1 8 1 3號 公報記載之熱滾輪延伸法、拉寬機延伸法等。而且，基本 上步驟的順序如上述，處理槽的數目、處理條件等並無限 制。 而且，上述步驟中可自由插入沒有記載的作爲其他目 的之步驟。作爲該步驟的例子，如硼酸處理後，浸漬於不 含硼酸之碘化物水溶液（碘化物處理）或浸漬於不含硼酸 -9- (6) (6)1359286 之氯化鋅水溶液（鋅處理）的步驟等。 膨脹步驟之目的在於除去薄膜表面的異物、除去薄膜 中的可塑劑、賦予下一步驟易染色的特性、薄膜的可塑化 等。處理條件係在可達成這些目的的範圍，且不產生基材 薄膜極度溶解、不透明等狀態的範圍內決定。首先氣體中 膨脹延伸的薄膜的情況，例如約20°C~70°C，較佳爲30°C 〜60°C的水溶液中浸漬薄膜。薄膜的浸漬時間爲30秒〜300 秒，更好爲60秒〜240秒的程度。首先膨脹未延伸的原結 構薄膜的情況，例如約l〇°C〜50°C，較佳爲20°C ~40°C的 水溶液中浸漬薄膜。薄膜的浸漬時間爲30秒〜3 00秒，更 好爲60秒〜24〇秒的程度。 於膨脹處理步驟，因薄膜的寬度方向膨脹容易產生皺 紋等的問題，使用擴張滾輪（expander roll)、螺旋滾輪 (spiral roll)、頂輥（crown roll) '交叉導輕（cross guider)、費曲棒（bend bar)、拉寬夾（tenter crip)等 習知拉寬裝置，除去薄膜的皺紋且傳送薄膜較佳。以安定 槽中薄膜的傳送爲目的，可在膨脹槽中以水中淋浴控制水 流，倂用 EPC裝置（邊緣位置控制裝置：檢查薄膜的端 部1防止薄膜蛇行的裝置）等。於本步驟，因在薄膜行走 的方向薄膜也膨脹擴大，爲使傳送方向的薄膜無鬆弛現 象，例如設計控制處理槽前後的傳送滾輪的速度等方式較 佳。而且，使用的膨脹處理槽，除純水外，也可使用添加 0 · 0 1重量％〜1 0重量％範圍之硼酸（記載於日本公開專利 特開平1 0- 1 5 3 709號公報）、氯化物（記載於日本公開專 -10- (7) (7)1359286 利特開平〇6-281816號公報）、無機酸、無機鹽、水溶性 有機溶劑、醇類等之水溶液。 染色處理步驟之目的在搏膜上吸附、配向二向色性色 素。處理條件係在可達成這些目的的範圍，且不產生基材 薄膜極度溶解 '不透明等狀態的範圍內決定。於本發明， 特別設置2段以上的染色浴依序進行染色。2段〜4段之染 色浴爲適當。此時，最後的染色浴含有硼酸。除最後的染 色浴外，各染色浴不含硼酸較佳。各染色浴一邊進行一軸 延伸一邊進行染色處理較佳，也可持續保持緊張狀態下進 行染色處理。 添加硼酸的情況，因包含二向色性色素，而與下述的 硼酸處理區別。對100重量份的水，包含約0.003重量份 以上的二向色性色素，溫度約4〇°C以下之染色浴。 使用碘作爲二向色性色素的情況，除最後的染色浴， 各染色浴的濃度，以重量比碘/碘化鉀/水=約0.003〜0.2 /約 0_1〜10/100，較佳爲約〇.〇卜0.1/約〇 Μ〜3.0/10(^最後的染 色浴的濃度’以重量比碘/碘化鉀/硼酸/水=約〇.〇〇3~0.2/ 約 0_1〜10/約 0.0S2.0/100，較佳爲約 〇.〇1〜0.1/約 0·1〜3.0 /約0.1~1.5/100。碘的含量，各染色浴可相同，或 者在上述範圍內依染色處理的順序遞減或遞增。 各染色浴的碘化鉀濃度，調整使其依染色處理的順序 變高較佳。碘化鉀濃度在各染色浴相同或依處理順序變低 的情況，長時間運轉時，破壞溶液濃度的平衡，無法安定 地保持偏光薄膜的品質。 -11 - (8) (8)1359286 此外，也可使用其他碘化物代替碘化鉀，例如碘化鋅 等。而且，也可其他碘化物與碘化鉀並用。即使是這些情 況’碘化物濃度，調整使其依染色處理的順序變高較佳。 而且，也可與碘化物以外的化合物共存，例如氯化鋅、氯 化鈷等》 最後的染色浴之硼酸濃度如上述，與延伸倍率間滿足 下述式較佳，不滿足該關係的情況，偏光薄膜的表面狀態 恐有惡化之虞。 b<-0.5lxa+3_77 此處，a表示1〇〇重量份的水中硼酸的含量（重量 份），b表示聚乙烯醇系薄膜從原結構至離開上述最後染 色浴爲止的總延伸倍率。 各染色浴之染色處理，例如約10 °C〜40 °c、較佳爲約 2 0 °C〜3 5 °C的溫度，進行約3 0秒〜6 0 0秒、較佳爲約6 0秒 ~3 0 0秒的浸漬處理。此處，各染色浴的溫度不到約1 〇 ^ 時，硼酸難以溶解，相反地超過約4 0°C時，聚乙烯醇的溶 解恐怕變多。 於各染色浴進行一軸延伸，在各染色浴分別單獨調整 延伸倍率較佳。因此，例如於各染色浴的入口側以及出口 側分別設置夾輪，可改變兩夾輪間的旋轉速度比較好。而 且，也可於染色浴中以及/或槽的出入口處設置擴張滾輪 (expander roll )、螺旋滾輪（spiral roll) '頂輕 -12- 1359286 ⑼ (crown roll )，交叉導輥（c r o s s g u i d e r )、彎曲棒 (bend bar )等，進行一軸延伸。 而且，膨脹處理後、染色處理前聚乙烯醇系薄膜也可 進行溼式延伸處理，而且必要時各染色浴之間至少其一也 可進行一軸延伸，或者各染色浴之間至少其一設置水洗 槽。 在2段以上的各染色浴進行一軸延伸的情況，延伸倍 率無特別限制，但採用以下2個態樣中任一個較佳。 (1 )在最初的染色浴之延伸倍率比第2段以後的染 色浴的總延伸倍率高。因此，因水洗後的乾燥時乾燥頸變 小，在乾燥爐產生皺紋的頻率變少。具體地，最初的染色 浴之延伸倍率約1.1 ~3.0倍的範圍內，且最初的染色浴之 延伸倍率爲第2段以後的染色浴的總延伸倍率的約 1 .05〜2.0倍的程度較佳。 (2)在最後的染色浴的延伸倍率比在其之前的染色 浴的總延伸倍率高。因此，硼酸處理步驟以後的步驟難以 緩和薄膜’可得偏光度高的偏光薄膜。具體地，最後的染 色浴之延伸倍率約1.05〜2.0倍的範圍內，且爲在其之前的 染色浴的總延伸倍率的約1 · 1 ~ 3 · 0倍的程度較佳。 硼酸處理係碘染色過的聚乙烯醇系薄膜浸漬於水100 重量份含有約1〜10重量份硼酸的水溶液。於硼酸水溶液 包含約1〜30重量份的碘化物較佳。作爲碘化物，例如碘 化:鉀 '拂化辞等’而且也可與碘化物以外的化合物例如氯 化綷、氯化銘、氯化锆、硫代硫酸鈉、亞硫酸鉀、硫酸鈉 -13- (10) (10)1359286 等共存。 該硼酸處理係除爲了交鏈的耐水化以外，爲調整色調 (防止帶藍色等）等而進行。爲了交鏈的耐水化的情況， 必要時除硼酸外，或與硼酸一起，使用乙二醛、戊二醒等 的交鏈劑。 而且，爲了耐水化之硼酸處理，也有稱爲交鏈處理、 固定化處理等名稱的情況。爲了調整色調進行硼酸處理的 情況，如此之硼酸處理也有稱爲補色處理、再染色處理等 名稱。而且於本發明，爲了耐水化之硼酸處理以及爲了調 整色調之硼酸處理，任一種單獨皆稱爲硼酸處理。 沒有特別區分爲了耐水化之硼酸處理以及爲了調整色 調之硼酸處理，依據以下的條件進行。 原結構薄膜在進行膨脹、染色、硼酸處理的情況，硼 酸處理以交鏈的耐水化爲目的時，使用水1 0 0重量份含約 3〜10重量份的硼酸、約1~2 0重量份的碘化物之硼酸處理 槽，通常在約50〜70t：、較佳爲 55~65t的溫度下進行。 浸漬時間通常爲30〜600秒的程度，較佳爲約60~420秒， 更好爲約90〜300秒。 此外，預先延伸的薄膜進行染色、硼酸處理的情況， 硼酸處理槽的溫度通常爲約50~85°C、較佳爲55~80°C的 溫度。 在爲了耐水化之硼酸處理後，也可進行爲了調整色調 之硼酸處理。爲了該目的，使用水100重量份含約卜5重 量份的硼酸、約3~30重量份的碘化物之硼酸處理槽，通 -14- (11) 1359286 常在約10〜45°c的溫度下進行。浸漬時間通常爲3-的程度’較佳爲約10〜2 40秒。爲了調整色調之 理’與爲了耐水化之硼酸處理比較，通常在較低的 度、較高的碘化物濃度、較低的溫度下進行。 這些硼酸處理可以複數個步驟進行，通常2~5 進行較多。於該情況，使用的各硼酸處理槽的水 成、溫度可在上述範圍內相同或相異皆可。上述爲 化之硼酸處理、爲了調整色調之硼酸處理可分別以 步驟進行。於硼酸處理步驟，與染色步驟同樣地， 薄膜的延伸。最終的總延伸倍率約爲4.5~7.0倍， 5.0〜6.5 倍。 硼酸處理後，進行水洗處理。水洗處理係例如 處理過的聚乙烯醇系薄膜浸漬於水中，水成爲淋浴 霧或浸漬與噴霧並用。於水洗處理水的溫度通常爲 的程度，浸漬時間爲2~120秒的程度。水洗後的乾 乾燥爐中約40〜10CTC的溫度下進行約60〜600秒。 於本發明，延伸處理後的分別步驟，進行張力 薄膜的張力分別實質上一定。在染色處理步驟結束 情況’在其後的硼酸處理步驟以及水洗處理步驟進 控制。 在如此製得的偏光薄膜的至少一面以接著劑貼 薄膜，可得偏光板。 作爲保護薄膜，例如三乙醯纖維素、二乙醯纖 乙醯纖維素系樹脂構成的薄膜，聚對苯二甲酸乙二 -3 00 秒 硼酸處 硼酸濃 個步驟 溶液組 了耐水 複數個 可進行 較佳爲 將硼酸 式的噴 2 〜4 0 〇C 燥，於 控制使 延伸的 行張力 附保護 維素之 酯 '聚 -15 - (12) (12)1359286 萘二甲酸乙二酯、聚對苯二甲酸丁二酯等聚酯構成的薄 膜，聚碳酸酯系樹脂構成的薄膜，環烯烴系樹脂構成的薄 膜。作爲市售熱塑性環烯烴系樹脂，例如德國Ticona公 司販售之「Topas」（註冊商標）、JSR (股）公司販售之 「Arton」（註冊商標） '日本 Zeon (股）公司販售之 「Zeonor」、「Zeonex」（任一皆註冊商標）、三井化學 (股）公司販售之「Apel」（註冊商標）等。以如此之環 烯烴系樹脂製膜成爲保護薄膜，於製膜時可適當使用溶劑 鑄膜法 '熔融擠出法等的習知方法。製成膜之環烯烴系樹 脂薄膜也有販售，例如積水化學工業（股）販售之 「Escena」、「SCA40」。 保護薄膜的厚度以薄者較佳，太薄的話強度降低，加 工性變差’另一方面，太厚的話，透明性降低，層合後產 生需要的痊癒時間變長等的問題。因此，保護薄膜適當的 厚度爲例如5〜2〇Ομπι的程度，較佳爲約10〜150μιη，更好 爲約 20~100μηι。 爲了提高接著劑與偏光薄膜以及/或與保護薄膜的接 著性，可對偏光薄膜以及/或保護薄膜進行電暈處理、火 焰處理、電漿處理、紫外線照射、引子（primer )塗佈處 理、皂化處理等的表面處理。 於保護薄膜’可進行防眩處理、防反射處理、硬塗處 理、防止帶電處理、防污處理等的表面處理之單獨或組合 處理》而且’保護薄膜以及/或保護薄膜表面保護層可具 有二苯甲酮系化合物、苯三唑系化合物等的紫外線吸收 -16- (13) (13)1359286 劑、苯磷酸系化合物、酞酸酯化合物等的可塑劑。 如此的保護薄膜可貼附於偏光薄膜的一面，也可貼附 於兩面。 偏光薄膜與保護薄膜係使用水溶劑系接著劑、有機溶 劑系接者劑、熱融系接著劑、無溶劑系接著劑等的接著劑 層合。作爲水溶劑系接著劑，例如聚乙烯醇系樹脂水溶 液、水性二液型胺基甲酸乙酯系乳液接著劑等，作爲有機 溶劑系接著劑’例如一液型胺基甲酸乙酯系接著劑等。使 用與偏光薄膜的接合面以巷化處理等的親水化處理過之乙 醒基纖維素系薄膜作爲保護薄膜的情況，適合使用聚乙烯 醇系樹脂水溶液作爲接著劑。用作接著劑之聚乙烯醇系樹 脂’除乙酸乙烯酯的單獨聚合物之聚乙酸乙烯酯進行皂化 處理所得之乙烯醇單聚合物外’乙酸乙烯酯以及可與其共 聚合之其他單量體的共聚合物進行皂化處理所得之乙烯醇 系共聚合物’再者這些氫氧基部分變性之變性聚乙烯醇系 聚合物等。於該接著劑，也可使用多價醛、水溶性環氧化 合物、三聚氰胺系化合物等作爲添加劑。 偏光薄膜與保護薄膜貼合的方法雖無特別限制，例如 在偏光薄膜或保護薄膜的表面均勻塗佈接著劑，塗佈面與 另一薄膜重疊，藉由滾輪貼合，乾燥的方法等。 通常接著劑係於調製後在約1 5〜4 〇 r的溫度下塗佈， 貼合溫度通常在15〜30 t程度的範圍。貼合後進行乾燥處 理’除去接著劑中包含的水等的溶劑，此時乾燥溫度通常 約3 0〜8 5 °C ’較佳爲4 0〜8 0 °C的範圍。然後，在約1 5〜8 5 -17 - (14) (14)1359286 °C ，較佳爲約 20〜50°C ，更好爲約 35~45°C的溫度環境 下，通常約1 ~90天的程度痊癒，使接著劑硬化。因該痊 癒時間長則生產性變差，痊癒時間爲1〜3 0天的程度，較 佳爲約1〜7天。 如此，可得隔著接著劑於偏光薄膜的一面或兩面貼附 保護薄膜之偏光板。 於本發明，保護薄膜可具有作爲相位差薄膜的功能、 作爲增亮薄膜的功能、作爲反射薄膜的功能、作爲半透過 反射薄膜的功能、作爲擴散薄膜的功能、作爲光學補償薄 膜的功能等的光學功能。於該情況，除於保護薄膜的表 面，藉由層合相位差薄膜、增亮薄膜、反射薄膜、半透過 反射薄膜、擴散薄膜、光學補償薄膜等的光學功能性薄 膜，可具有如此的功能之外，可賦予保護薄膜本身如此的 功能。而且，可使保護薄膜本身具有如增亮薄膜功能之擴 散薄膜等之複數功能。 例如藉由於上述的保護薄膜進行記載於日本專利第 2 84 1 3 77號公報、專利第3 094 1 1 3號公報等的延伸處理， 記載於專利第3168850號公報等的處理，可賦予作爲相位 差薄膜的功能。而且，藉由於上述保護薄膜，以記載於曰 本公開專利特開2002-169025號公報、特開2003-29030號 公報的方法形成細微孔，或者選擇反射中心波長相異之2 層以上的膽固醇狀液晶層重疊，可賦予作爲增亮薄膜的功 能。 於上述的保護薄膜，藉由蒸鍍、濺鍍等形成金屬薄 -18- (15) (15)1359286 膜’可賦予作爲反射薄膜或半透過反射薄膜的功能。藉由 塗佈含微粒子的樹脂於上述保護薄膜，可賦予作爲擴散薄 膜的功能。而且，藉由塗佈盤狀液晶性化合物等的液晶性 化合物於上述保護薄膜使其配向，可賦予作爲光學補償薄 膜的功能。而且，也可使用適當接著劑，將商品名： DBEF ( 3Μ (股）公司製）等的增亮薄膜，商品名：wv 薄膜（富士寫真薄膜（股）製）等的改良視角薄膜，商品 名：Sumkajight (註冊商標）（住友化學工業（股）製） 等的相位差薄膜等的市售的光學功能性薄膜直接貼合於偏 光薄膜。 以下表示的實施例更具體說明本發明，但本發明不限 於這些例子》 〔實施例1〕 厚度75μιη的聚乙燦醇薄膜（Kuraray Vinylon VF-PS # 7500、聚合度2400、皂化度99.9莫耳％以上）於30 °C 純水，保持薄膜不鬆弛狀態浸漬約1 3 0秒，使薄膜充分 膨脹（膨脹約1 .2倍）。 然後，浸漬於碘/碘化鉀/水重量比爲0.02/ 1.0/ 1 00的 30 °C水溶液，且進行1.75倍之一軸延伸。再者，浸漬於 碘/碘化鉀/硼酸/水重量比爲0.02/1.5/0.2/100的30 °C水溶 液，且進行1 ·4倍之一軸延伸，從原結構的總延伸倍率爲 3倍。然後，浸漬於碘化鉀/硼酸/水重量比爲10/5/100的 60t水溶液，進行耐水化處理且進行一軸延伸直至從原結 -19- (16) (16)1359286 構的總延伸倍率成爲5.9倍爲止。耐水化處理後，以1 〇 t 純水水洗約1 〇秒。水洗後，於60 °C乾燥2分鐘，得到厚 度28μπι的偏光薄膜。目視檢查該偏光薄膜的表面狀態， 薄膜表面顯示良好的鏡面反射。 於偏光薄膜的兩面塗佈聚乙烯醇系接著劑，於兩面貼 合保護薄膜〔表面施以皂化處理之三乙醯基纖維素薄膜 「Fujitac (註冊商標）T80UNL」、富士寫真薄膜（股） 製 '厚度80μιη〕，於60°C乾燥5分鐘，得到偏光板。該 偏光薄膜在直交泥科爾（crossed Nicol)狀態下於暗室以 目視觀察，有輕微染色不均。而且，染色不均確認是因從 偏光板漏光的程度。 〔比較例1〕 除第2段染色浴不加硼酸以外，與實施例1同樣的方 式得到偏光板。目視檢查該偏光薄膜的表面狀態，螢光燈 的反射光無法顯示鏡面反射，稍帶白'色，外觀不良。 〔比較例2〕 除第1段染色浴硼酸爲0.2重量份以外，與實施例I 同樣的方式得到偏光板。該偏光薄膜在直交泥科爾 (crossed Nicol)狀態下於暗室以目視觀察，觀察到染色 不均比實施例1多*Unstretched film. Industrially, the width of the film is practically about 1 500 mm to 4 mm. The unstretched film is sequentially subjected to expansion treatment, dyeing treatment, "boric acid treatment, water washing treatment", and finally dried to obtain a thickness of the polyvinyl alcohol-based polarizing film. For example, the extent is about 5 to 50 μm. The polarizing film of the present invention is a method for producing a polyvinyl alcohol-based one-axis stretch film which adsorbs a dichroic dye, and is roughly classified into two production methods: a younger one is a polyethene alcohol film in air or an inert gas. After the middle-axis extension, the solution treatment of the expansion treatment, the dyeing treatment, the boric acid treatment, and the water washing treatment is carried out in succession, and finally the drying method is performed. The second is an unextended polyethylidene alcohol-based film 'swelling treatment in an aqueous solution, dyeing treatment' boric acid treatment, water treatment treatment, and a shaft in the boric acid treatment step and/or its previous step 'wet' Extend and finally dry. In either method, the one-axis extension may be carried out in one step or in two or more steps, and the plurality of steps are preferably carried out. The stretching method can be carried out by a conventional method, for example, extending between the two pinch wheels of the transfer film to extend the difference in the rotational speed, as described in Japanese Patent No. 2 73 1 8 1 3, the hot roller extension method, and the widening. Machine extension method, etc. Further, the order of the basic steps is as described above, and the number of processing tanks, processing conditions, and the like are not limited. Further, in the above steps, steps which are not described as other steps can be freely inserted. As an example of this step, after boric acid treatment, immersed in an aqueous solution of boric acid-free iodide (iodide treatment) or immersed in an aqueous solution of zinc chloride containing no boric acid-9-(6) (6) 1359286 (zinc treatment) Steps, etc. The purpose of the expansion step is to remove foreign matter on the surface of the film, to remove the plasticizer in the film, to impart dyeability to the next step, to plasticize the film, and the like. The treatment conditions are determined within a range in which these objects can be achieved, and in a range in which the substrate film is extremely dissolved or opaque. First, in the case of a film which is expanded and extended in a gas, for example, a film is immersed in an aqueous solution of about 20 ° C to 70 ° C, preferably 30 ° C to 60 ° C. The immersion time of the film is from 30 seconds to 300 seconds, more preferably from 60 seconds to 240 seconds. When the unstretched original structural film is first expanded, for example, the film is immersed in an aqueous solution of about 10 ° C to 50 ° C, preferably 20 ° C to 40 ° C. The immersion time of the film is from 30 seconds to 3,000 seconds, preferably from 60 seconds to 24 seconds. In the expansion treatment step, problems such as wrinkles are likely to occur due to expansion in the width direction of the film, and an expander roll, a spiral roll, a crown roll, a cross guide, and a fee are used. A conventional stretching device such as a bent bar or a tenter crip removes wrinkles of the film and preferably transports the film. For the purpose of conveying the film in the stable tank, the water flow can be controlled by the shower in the expansion tank, and the EPC device (edge position control device: the end portion of the film 1 to prevent film snaking) can be used. In this step, since the film is also expanded and expanded in the direction in which the film travels, in order to make the film in the transport direction free from slack, for example, it is preferable to design the speed of the transfer roller before and after the control groove. Further, in the expansion treatment tank to be used, in addition to the pure water, a boric acid in a range of from 0. 01% by weight to 10% by weight may be used (described in Japanese Laid-Open Patent Publication No. Hei 10-153037). Chloride (described in Japanese Laid-Open Patent Publication No. Hei 10-(7) (7) 1359286, Japanese Patent Publication No. Hei 6-281816, an aqueous solution of an inorganic acid, an inorganic salt, a water-soluble organic solvent, or an alcohol. The purpose of the dyeing treatment step is to adsorb and align the dichroic color on the membrane. The treatment conditions are determined within a range in which these objects can be achieved, and in a range in which the substrate film is extremely insolubilized, such as opacity. In the present invention, dyeing baths of two or more stages are particularly provided for sequential dyeing. The dye baths of the 2nd to 4th paragraphs are appropriate. At this point, the final dye bath contains boric acid. In addition to the final dye bath, it is preferred that each dye bath does not contain boric acid. Each of the dyeing baths is preferably subjected to a dyeing treatment while performing one-axis extension, and dyeing treatment is also continued while maintaining tension. When boric acid is added, it contains a dichroic dye and is distinguished from the following boric acid treatment. A dye bath containing about 0.003 part by weight or more of a dichroic dye and a temperature of about 4 ° C or less for 100 parts by weight of water. When iodine is used as the dichroic dye, except for the final dye bath, the concentration of each dye bath is iodine/potassium iodide/water = about 0.003 to 0.2 / about 0_1 to 10/100, preferably about 〇. 〇 0.1 0.1 / about 3.0 ~ 3.0/10 (^ the final dye bath concentration ' by weight ratio iodine / potassium iodide / boric acid / water = about 〇. 〇〇 3 ~ 0.2 / about 0_1 ~ 10 / about 0.0S2.0 /100, preferably about 〇.〇1~0.1/about 0·1~3.0/about 0.1~1.5/100. The content of iodine may be the same for each dye bath, or may be decreased in the order of dyeing treatment within the above range or The concentration of potassium iodide in each dye bath is adjusted to be higher in the order of dyeing treatment. The concentration of potassium iodide is the same in each dye bath or in the order of treatment, and the balance of solution concentration is not broken during long-term operation. Maintain the quality of the polarizing film in a stable manner. -11 - (8) (8) 1359286 In addition, other iodides may be used instead of potassium iodide, such as zinc iodide, etc. Further, other iodides may be used together with potassium iodide. 'Iodide concentration, adjusted to make it higher in the order of dyeing treatment. Moreover, It may coexist with a compound other than iodide, for example, zinc chloride, cobalt chloride, etc. The concentration of boric acid in the final dyeing bath is as described above, and the following formula is preferably satisfied with the stretching ratio, and the polarizing film is not satisfied. The surface state may be deteriorated. b<-0.5lxa+3_77 Here, a represents the content (parts by weight) of boric acid in 1 part by weight of water, and b represents the polyvinyl alcohol-based film from the original structure to the last The total stretching ratio until the dyeing bath. The dyeing treatment of each dye bath, for example, about 10 ° C to 40 ° C, preferably about 20 ° C to 35 ° C, is carried out for about 30 seconds to 600 ° Second, preferably about 60 seconds to 300 seconds of immersion treatment. Here, when the temperature of each dye bath is less than about 1 〇 ^, boric acid is difficult to dissolve, and conversely when it exceeds about 40 ° C, polyethylene The dissolution of the alcohol is likely to increase. It is preferred to carry out one-axis extension in each dye bath, and it is preferable to separately adjust the stretching ratio in each dye bath. Therefore, for example, a pinch wheel is provided on the inlet side and the outlet side of each dye bath, and the two pinch wheels can be changed. The rotation speed between the two is better. Moreover, it can also be dyed. An expander roll, a spiral roll 'head light-12-1359286 (9) (crown roll), a cross guider, a bend bar, etc. are provided at the entrance and exit of the middle and/or the groove. Further, the one-axis extension is performed. Further, the polyvinyl alcohol-based film may be subjected to a wet stretching treatment after the expansion treatment and before the dyeing treatment, and at least one of the dyeing baths may be subjected to one-axis stretching, or at least between the dyeing baths, if necessary. One of them sets a washing tank. In the case where the dyeing baths of two or more stages are subjected to one-axis stretching, the stretching ratio is not particularly limited, but any of the following two aspects is preferable. (1) The stretching ratio of the first dye bath is higher than the total stretching ratio of the dye bath after the second stage. Therefore, the drying neck is reduced during drying after washing, and the frequency of wrinkles in the drying furnace is reduced. Specifically, the stretching ratio of the first dye bath is in the range of about 1.1 to 3.0 times, and the stretching ratio of the first dye bath is about 1.05 to 2.0 times the total stretching ratio of the dye bath after the second stage. good. (2) The stretching ratio in the final dye bath is higher than the total stretching ratio of the dye bath before it. Therefore, it is difficult to alleviate the film "a polarizing film having a high degree of polarization" after the step of the boric acid treatment step. Specifically, the stretching ratio of the final dye bath is in the range of about 1.05 to 2.0 times, and is preferably about 1 · 1 to 3 · 0 times the total stretching ratio of the dye bath before it. The boric acid-treated iodine-dyed polyvinyl alcohol-based film is immersed in 100 parts by weight of water containing about 1 to 10 parts by weight of boric acid. It is preferred to contain about 1 to 30 parts by weight of the iodide in the aqueous boric acid solution. As an iodide, for example, iodide: potassium 'deuterated words' and may also be combined with compounds other than iodide such as cesium chloride, chlorinated, zirconium chloride, sodium thiosulfate, potassium sulfite, sodium sulfate-13 - (10) (10) 1359286 and so on. This boric acid treatment is carried out in order to adjust the color tone (to prevent bluing, etc.) in addition to the water resistance of the cross-linking. In order to withstand the hydration of the cross-linking, a side chaining agent such as glyoxal or pentane bromide may be used in addition to boric acid or in combination with boric acid. Further, in the case of boric acid treatment which is resistant to hydration, there are cases where the name is called a cross-linking treatment or an immobilization treatment. In order to adjust the color tone for boric acid treatment, such a boric acid treatment is also called a complementary color treatment, a re-dye treatment, and the like. Further, in the present invention, any one of them is referred to as boric acid treatment for the hydration-resistant boric acid treatment and for the boric acid treatment for adjusting the color tone. There is no particular distinction between boric acid treatment for hydration resistance and boric acid treatment for adjusting the color tone, and the following conditions were followed. When the original structural film is subjected to expansion, dyeing, or boric acid treatment, and boric acid treatment is used for the purpose of water resistance of the cross-linking, 10 parts by weight of water is used, and about 3 to 10 parts by weight of boric acid is used, and about 1 to 20 parts by weight is used. The boric acid treatment tank of the iodide is usually carried out at a temperature of about 50 to 70 t:, preferably 55 to 65 t. The immersion time is usually from 30 to 600 seconds, preferably from about 60 to 420 seconds, more preferably from about 90 to 300 seconds. Further, in the case where the pre-stretched film is subjected to dyeing or boric acid treatment, the temperature of the boric acid treatment tank is usually about 50 to 85 ° C, preferably 55 to 80 ° C. After the boric acid treatment for water resistance, a boric acid treatment for adjusting the color tone can also be performed. For this purpose, 100 parts by weight of boric acid treatment tank containing about 5 parts by weight of boric acid and about 3 to 30 parts by weight of iodide is used, and the temperature of 14-(11) 1359286 is usually about 10 to 45 ° C. Go on. The immersion time is usually from a degree of from 3 to preferably from about 10 to 2 40 seconds. In order to adjust the color tone, it is usually carried out at a lower degree, a higher iodide concentration, and a lower temperature than the boric acid treatment for hydration resistance. These boric acid treatments can be carried out in a plurality of steps, usually 2 to 5 times. In this case, the aqueous solution and the temperature of each of the boric acid treatment tanks used may be the same or different within the above range. The above-described boric acid treatment and boric acid treatment for adjusting the color tone can be carried out in separate steps. In the boric acid treatment step, as in the dyeing step, the film is stretched. The final total stretch ratio is about 4.5 to 7.0 times, 5.0 to 6.5 times. After boric acid treatment, it is washed with water. The water washing treatment is, for example, a treated polyvinyl alcohol-based film immersed in water, and the water is used as a shower mist or a combination of dipping and spraying. The temperature of the water to be treated is usually about 2 to 120 seconds. The dried drying oven after washing is carried out at a temperature of about 40 to 10 CTC for about 60 to 600 seconds. In the present invention, the tension of the tension film is substantially constant in the respective steps after the stretching treatment. At the end of the dyeing treatment step, the subsequent boric acid treatment step and the water washing treatment step are controlled. A polarizing plate can be obtained by sticking a film with an adhesive on at least one side of the polarizing film thus obtained. As a protective film, for example, a film composed of triacetyl cellulose, diethyl fluorene cellulose fiber, polyethylene terephthalate - 300 seconds boric acid boric acid concentrated step solution group can be carried out with a plurality of water resistance Preferably, the boric acid type spray is sprayed to 2 to 40 〇C to control the elongation of the line tension with the protective ester of the ester 'poly-15 - (12) (12) 1359286 naphthalenedicarboxylate, poly pair A film made of a polyester such as butyl phthalate, a film made of a polycarbonate resin, or a film made of a cycloolefin resin. As a commercially available thermoplastic cycloolefin-based resin, for example, "Topas" (registered trademark) sold by Ticona, Germany, and "Arton" (registered trademark) sold by JSR (share) company - sold by Japan Zeon Co., Ltd. Zeonor, "Zeonex" (any registered trademark), "Apel" (registered trademark) sold by Mitsui Chemicals Co., Ltd., etc. A membrane made of such a cyclic olefin resin is used as a protective film, and a conventional method such as a melt casting method such as a solvent casting method can be suitably used for film formation. The cycloolefin resin film which is formed into a film is also sold, for example, "Escena" and "SCA40" which are sold by Sekisui Chemical Industry Co., Ltd. The thickness of the protective film is preferably as thin as possible. When the thickness is too thin, the strength is lowered and the workability is deteriorated. On the other hand, if it is too thick, the transparency is lowered, and the required healing time is prolonged after lamination. Therefore, the protective film has a suitable thickness of, for example, 5 to 2 μm, preferably about 10 to 150 μm, more preferably about 20 to 100 μm. In order to improve the adhesion between the adhesive and the polarizing film and/or the protective film, the polarizing film and/or the protective film may be subjected to corona treatment, flame treatment, plasma treatment, ultraviolet irradiation, primer coating treatment, saponification. Surface treatment such as processing. The protective film can be subjected to an anti-glare treatment, an anti-reflection treatment, a hard coating treatment, a surface treatment for preventing elective treatment, an anti-fouling treatment, or the like, and the protective film and/or the protective film surface protective layer can have two A UV-absorbing benzophenone-based compound or a benzotriazole-based compound, such as a plasticizer such as a 16-(13) (13) 1359286 agent, a benzene phosphate compound or a phthalate compound. Such a protective film can be attached to one side of the polarizing film or attached to both sides. The polarizing film and the protective film are laminated using an adhesive such as an aqueous solvent-based adhesive, an organic solvent-based adhesive, a hot-melt adhesive, or a solventless adhesive. The aqueous solvent-based adhesive agent, for example, a polyvinyl alcohol-based resin aqueous solution or an aqueous two-component urethane-based emulsion adhesive, is used as an organic solvent-based adhesive agent, for example, a one-liquid type urethane-based adhesive. . When a hydrophilic phase-treated Ethylene-based cellulose-based film such as a road surface is treated as a protective film by a bonding surface with a polarizing film, a polyvinyl alcohol-based resin aqueous solution is preferably used as the adhesive. Polyvinyl acetate-based resin used as an adhesive 'polyvinyl acetate of a single polymer of vinyl acetate is saponified to obtain a vinyl alcohol single-polymer outer vinyl acetate and other mono-components copolymerizable therewith A vinyl alcohol-based copolymer obtained by saponification of a copolymer, and a modified polyvinyl alcohol-based polymer in which these hydroxyl groups are partially denatured. As the binder, a polyvalent aldehyde, a water-soluble epoxide, a melamine-based compound or the like can also be used as an additive. The method of bonding the polarizing film to the protective film is not particularly limited, and for example, a method of uniformly applying an adhesive to the surface of the polarizing film or the protective film, overlapping the coated surface with another film, laminating by a roller, drying, or the like. Usually, the adhesive is applied at a temperature of about 15 to 4 Torr after the preparation, and the bonding temperature is usually in the range of about 15 to 30 Torr. After the bonding, the drying treatment is carried out, and the solvent such as water contained in the adhesive is removed. The drying temperature is usually about 30 to 85 ° C., preferably 40 to 80 ° C. Then, at about 1 5 to 8 5 -17 - (14) (14) 1359286 ° C, preferably about 20 to 50 ° C, more preferably about 35 to 45 ° C, usually about 1 ~ The degree of healing in 90 days hardens the adhesive. Since the production time is deteriorated due to the long recovery time, the recovery time is 1 to 30 days, preferably about 1 to 7 days. Thus, a polarizing plate in which a protective film is attached to one or both sides of the polarizing film via an adhesive can be obtained. In the present invention, the protective film may have a function as a retardation film, a function as a brightness enhancement film, a function as a reflective film, a function as a semi-transmissive reflection film, a function as a diffusion film, a function as an optical compensation film, and the like. Optical function. In this case, in addition to the surface of the protective film, an optical functional film laminated with a retardation film, a brightness enhancement film, a reflective film, a semi-transmissive reflective film, a diffusion film, an optical compensation film, or the like can have such a function. In addition, the protective film itself can be imparted with such a function. Further, the protective film itself can have a plurality of functions such as a diffusing film which enhances the function of the film. For example, the processing of the above-mentioned protective film, which is described in Japanese Patent No. 2,84, 3, 77, and Japanese Patent No. 3,094,1, and the like, is described in Japanese Patent No. 3,168,850, and the like. The function of the poor film. Further, by the above-mentioned protective film, fine pores are formed by the method described in JP-A-2002-169025, JP-A-2003-29030, or two or more layers of cholesterol having different reflection center wavelengths are selected. The liquid crystal layers overlap and impart a function as a brightness enhancement film. In the above protective film, a thin metal -18-(15)(15)1359286 film can be formed by vapor deposition, sputtering, or the like, and can be provided as a reflective film or a semi-transmissive reflective film. By applying the fine particle-containing resin to the above protective film, it is possible to impart a function as a diffusion film. In addition, by applying a liquid crystal compound such as a discotic liquid crystalline compound to the protective film to align it, it is possible to impart a function as an optical compensation film. In addition, a modified film such as a brightening film such as DBEF (manufactured by KK), or a modified viewing angle film such as a wv film (manufactured by Fuji Photo Film Co., Ltd.), may be used. A commercially available optical functional film such as a phase difference film such as Sumkajight (registered trademark) (manufactured by Sumitomo Chemical Co., Ltd.) is directly bonded to a polarizing film. The examples shown below more specifically illustrate the present invention, but the present invention is not limited to these examples. [Example 1] A polyacetate film having a thickness of 75 μm (Kuraray Vinylon VF-PS # 7500, degree of polymerization 2400, degree of saponification 99.9 m More than %) in pure water at 30 ° C, keeping the film in a state of no relaxation for about 130 seconds, so that the film is fully expanded (about 1.2 times expansion). Then, it was immersed in an aqueous solution of 30 ° C in which the weight ratio of iodine / potassium iodide / water was 0.02 / 1.0 / 1 00, and 1.75 times of one-axis extension was performed. Further, it was immersed in an aqueous solution of 30 ° C in which the weight ratio of iodine/potassium iodide/boric acid/water was 0.02/1.5/0.2/100, and one-fourth of the axial extension was carried out, and the total stretching ratio from the original structure was three times. Then, it was immersed in a 60 t aqueous solution of potassium iodide/boric acid/water in a weight ratio of 10/5/100, subjected to water resistance treatment and subjected to one-axis extension until the total stretching ratio from the original knot -19-(16) (16) 1359286 was 5.9. Up to the end. After hydration resistance, wash with 1 〇 t of pure water for about 1 〇. After washing with water, it was dried at 60 ° C for 2 minutes to obtain a polarizing film having a thickness of 28 μm. The surface state of the polarizing film was visually inspected, and the film surface showed good specular reflection. A polyvinyl alcohol-based adhesive is applied to both surfaces of the polarizing film, and a protective film is bonded to both surfaces (a saponified triethyl fluorene-based cellulose film "Fujitac (registered trademark) T80UNL" and a Fuji photo film) The thickness was 80 μm, and it was dried at 60 ° C for 5 minutes to obtain a polarizing plate. The polarizing film was visually observed in a dark room in a crossed Nicol state with slight uneven dyeing. Moreover, the uneven dyeing was confirmed to be due to light leakage from the polarizing plate. [Comparative Example 1] A polarizing plate was obtained in the same manner as in Example 1 except that boric acid was not added to the dyeing bath in the second stage. The surface state of the polarizing film was visually inspected, and the reflected light of the fluorescent lamp could not show specular reflection, which was slightly white and had a poor appearance. [Comparative Example 2] A polarizing plate was obtained in the same manner as in Example 1 except that the first stage dyeing bath boric acid was 0.2 part by weight. The polarizing film was visually observed in a dark room in a crossed Nicol state, and uneven dyeing was observed to be more than that in Example 1.