TW202007518A - Polarizing film and method for manufacturing polarizing film - Google Patents

Polarizing film and method for manufacturing polarizing film Download PDF

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TW202007518A
TW202007518A TW108119950A TW108119950A TW202007518A TW 202007518 A TW202007518 A TW 202007518A TW 108119950 A TW108119950 A TW 108119950A TW 108119950 A TW108119950 A TW 108119950A TW 202007518 A TW202007518 A TW 202007518A
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polarizing film
pva
based resin
extension
stretching
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TWI801599B (en
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高永幸佑
後藤周作
嶋津亮
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日商日東電工股份有限公司
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/0073—Optical laminates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
    • B29C55/04—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique
    • B29C55/06—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique parallel with the direction of feed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/00634—Production of filters
    • B29D11/00644—Production of filters polarizing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/00865—Applying coatings; tinting; colouring
    • B29D11/00894—Applying coatings; tinting; colouring colouring or tinting
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/14—Protective coatings, e.g. hard coatings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • H05B33/02—Details
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2029/00—Use of polyvinylalcohols, polyvinylethers, polyvinylaldehydes, polyvinylketones or polyvinylketals or derivatives thereof as moulding material
    • B29K2029/04—PVOH, i.e. polyvinyl alcohol

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Optics & Photonics (AREA)
  • General Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Ophthalmology & Optometry (AREA)
  • Polarising Elements (AREA)
  • Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
  • Electroluminescent Light Sources (AREA)

Abstract

The present invention provides a polarizing film capable of reducing streaking. The polarizing film according to the present invention has a thickness of 8 [mu]m or less; the average difference between the maximum and minimum thicknesses of the polarizing film in each 50-mm region from one end to the other end in a direction perpendicular to the absorption axis is 70 nm or less.

Description

偏光膜及偏光膜之製造方法Polarizing film and method of manufacturing polarizing film

本發明係關於一種偏光膜及偏光膜之製造方法。The invention relates to a polarizing film and a method for manufacturing the polarizing film.

發明背景 在代表性之影像顯示裝置的液晶顯示裝置中，依據其影像形成方式而於液晶單元的兩側配置有偏光膜。且，隨著薄型顯示器的普及，還提出了搭載有機EL面板之顯示器(OLED)、使用有利用量子點等無機發光材料的顯示面板之顯示器(QLED)，而偏光膜亦可應用於該等影像顯示裝置。偏光膜之製造方法，例如已提出有一種將具有樹脂基材與聚乙烯醇(PVA)系樹脂層之積層體延伸，然後施以染色處理，以在樹脂基材上獲得偏光膜的方法(例如專利文獻1)。藉由這種方法可獲得厚度較薄的偏光膜，所以能對近年之影像顯示裝置的薄型化有所貢獻而備受矚目。然而，如上述之以往的薄型偏光膜在應用於影像顯示裝置時，會有視辨出條痕不均之情形。Background of the invention In a liquid crystal display device of a typical image display device, polarizing films are arranged on both sides of the liquid crystal cell according to its image forming method. Moreover, with the popularization of thin displays, displays equipped with organic EL panels (OLED) and displays using display panels using quantum dots and other phosphors (QLED) have also been proposed, and polarizing films can also be applied to such images Display device. For the manufacturing method of the polarizing film, for example, there has been proposed a method of extending a laminate having a resin substrate and a polyvinyl alcohol (PVA) resin layer, and then applying a dyeing treatment to obtain a polarizing film on the resin substrate (for example Patent Literature 1). By this method, a thin polarizing film can be obtained, so it can contribute to the thinning of the image display device in recent years and attracts attention. However, when the above-mentioned conventional thin polarizing film is applied to an image display device, uneven streaks may be visually recognized.

先前技術文獻 專利文獻 專利文獻1：日本特開2001-343521號公報Prior technical literature Patent Literature Patent Document 1: Japanese Patent Laid-Open No. 2001-343521

發明概要 發明欲解決之課題 本發明是為了解決上述以往之課題而成者，其主要目的在於提供一種可抑制條痕不均產生的偏光膜及所述偏光膜之製造方法。Summary of the invention Problems to be solved by invention The present invention was made to solve the above-mentioned conventional problems, and its main object is to provide a polarizing film capable of suppressing the occurrence of unevenness and a method of manufacturing the polarizing film.

用以解決課題之方法 本發明之偏光膜的厚度為8μm以下，且沿與吸收軸正交之方向從一端部至另一端部為止每50mm之區域的最大厚度與最小厚度之差的平均值為70nm以下。 在一實施形態中，單體透射率為44.5%以上，且偏光度為99.0%以上。 根據本發明之另一面向係提供一種偏光板。該偏光板具有：上述偏光膜與配置於上述偏光膜之至少一側的保護層。 根據本發明之另一面向係提供一種偏光膜之製造方法。該偏光膜之製造方法包含以下步驟：於熱塑性樹脂基材之單側形成含聚乙烯醇系樹脂之聚乙烯醇系樹脂層，而製成積層體；及，對上述積層體依序施行空中延伸處理與染色處理；上述空中延伸處理後之上述聚乙烯醇系樹脂層利用衰減全反射分光測定算出之結晶化指數為1.55以上且1.7以下，且定向函數為0.22以上且0.31以下。 在一實施形態中，係於上述空中延伸處理之後更包含對上述積層體施行水中延伸處理；上述空中延伸處理之延伸倍率為3.0倍以上，且上述水中延伸處理之延伸倍率為1.8倍以下。The method used to solve the problem The thickness of the polarizing film of the present invention is 8 μm or less, and the average value of the difference between the maximum thickness and the minimum thickness per area of 50 mm from one end to the other end in the direction orthogonal to the absorption axis is 70 nm or less. In one embodiment, the single transmittance is 44.5% or more, and the degree of polarization is 99.0% or more. According to another aspect of the present invention, a polarizing plate is provided. The polarizing plate includes the polarizing film and a protective layer disposed on at least one side of the polarizing film. According to another aspect of the present invention, a method for manufacturing a polarizing film is provided. The manufacturing method of the polarizing film includes the following steps: forming a polyvinyl alcohol-based resin layer containing a polyvinyl alcohol-based resin on one side of a thermoplastic resin substrate to form a laminate; and, sequentially performing air stretching on the laminate Treatment and dyeing treatment; the polyvinyl alcohol-based resin layer after the air stretching process has a crystallization index calculated by attenuation total reflection spectrometry of 1.55 or more and 1.7 or less, and the orientation function is 0.22 or more and 0.31 or less. In one embodiment, the air stretching process further includes performing an underwater stretching process on the laminate; the stretching magnification of the above-mentioned air stretching process is 3.0 times or more, and the stretching magnification of the underwater stretching process is 1.8 times or less.

用以實施發明之形態 以下說明本發明之實施形態，惟本發明不受該等實施形態限定。Forms for carrying out the invention The embodiments of the present invention are described below, but the present invention is not limited by these embodiments.

A.偏光膜 本發明之一實施形態之偏光膜的厚度為8μm以下，且沿與吸收軸正交之方向從一端部至另一端部為止每50mm區域的最大厚度與最小厚度之差的平均值(以下有時稱為厚度參差)為70nm以下。厚度參差舉例而言可從上述一端部至另一端部為止以間隔2mm測定偏光膜之厚度，算出每50mm區域內的最大厚度與最小厚度之差，再算出各區域之上述差的平均值從而求得。偏光膜的厚度在代表上可使用光學干涉膜厚計測得。以往之薄型偏光膜會因為其製造方法等而產生沿與吸收軸正交之方向的厚度參差，結果在應用於影像顯示裝置時會有產生沿吸收軸之條痕不均的情形。本實施形態之偏光膜不論厚度是否非常薄，厚度參差皆小。所述偏光膜在應用於影像顯示裝置時可抑制條痕不均產生。A. Polarizing film The thickness of the polarizing film according to one embodiment of the present invention is 8 μm or less, and the average value of the difference between the maximum thickness and the minimum thickness per 50 mm region from one end to the other end in the direction orthogonal to the absorption axis (the following may be It is called thickness variation) and is 70 nm or less. For example, for thickness variation, the thickness of the polarizing film can be measured at intervals of 2 mm from one end to the other end, the difference between the maximum thickness and the minimum thickness in each 50 mm area can be calculated, and then the average value of the above differences in each area can be calculated to obtain Get. The thickness of the polarizing film can be representatively measured using an optical interference film thickness meter. Conventional thin polarizing films have uneven thickness in the direction orthogonal to the absorption axis due to their manufacturing method, etc. As a result, when applied to an image display device, uneven streaks along the absorption axis may occur. The polarizing film of this embodiment is small in thickness regardless of whether it is very thin or not. When the polarizing film is applied to an image display device, it can suppress the unevenness of streak.

偏光膜的厚度宜為1μm~8μm，1μm~7μm較佳，2μm~5μm更佳。厚度參差宜為50nm以下，較佳為40nm以下，尤佳為30nm以下。厚度參差宜小，但現實上之下限例如為5nm。The thickness of the polarizing film is preferably 1 μm to 8 μm, preferably 1 μm to 7 μm, and more preferably 2 μm to 5 μm. The thickness variation is preferably 50 nm or less, preferably 40 nm or less, and particularly preferably 30 nm or less. The thickness variation should be small, but the lower limit is actually 5 nm, for example.

偏光膜之單體透射率宜為44.5%以上，且偏光度宜為99.0%以上。偏光膜之單體透射率更宜為45.0%以上。偏光膜之偏光度更宜為99.5%以上，且99.9%以上更佳。上述單體透射率在代表上係使用紫外線可見光分光光度計來測定並進行光視效能校正所得之Y值。上述偏光度在代表上係以使用紫外線可見光分光光度計測定並進行光視效能校正所得之平行透射率Tp及正交透射率Tc為基準，透過下述式來求得。 偏光度(%)={(Tp-Tc)/(Tp+Tc)}1/2 ×100The single transmittance of the polarizing film should be above 44.5%, and the degree of polarization should be above 99.0%. The single transmittance of the polarizing film is more preferably 45.0% or more. The polarization degree of the polarizing film is more preferably 99.5% or more, and more preferably 99.9% or more. The above-mentioned monomer transmittance is representatively a Y value obtained by using an ultraviolet visible light spectrophotometer to measure and correct the optical performance. The above-mentioned polarization degree is representatively obtained by the following formula based on the parallel transmittance Tp and the orthogonal transmittance Tc measured by using an ultraviolet visible spectrophotometer and corrected for the optical performance. Polarization (%)={(Tp-Tc)/(Tp+Tc)} 1/2 ×100

上述偏光膜之製造方法包含以下步驟：於熱塑性樹脂基材之單側形成含聚乙烯醇系樹脂(PVA系樹脂)之聚乙烯醇系樹脂層(PVA系樹脂層)，而製成積層體；及，對上述積層體依序施行空中延伸處理與染色處理。上述空中延伸處理後之上述PVA系樹脂層利用衰減全反射分光(ATR)測定算出之結晶化指數為1.55以上且1.7以下，且定向函數為0.22以上且0.31以下。依上述將空中延伸處理後之PVA系樹脂層的結晶化指數及定向函數控制在上述範圍內，可製造出厚度薄、厚度參差小並且具有高光學特性的偏光膜。The manufacturing method of the polarizing film includes the following steps: forming a polyvinyl alcohol-based resin layer (PVA-based resin layer) containing a polyvinyl alcohol-based resin (PVA-based resin) on one side of the thermoplastic resin substrate to form a laminate; And, aerial stretching and dyeing are sequentially performed on the above-mentioned laminate. The PVA-based resin layer after the air stretching process has a crystallization index calculated by attenuation total reflection spectrometry (ATR) measurement of 1.55 or more and 1.7 or less, and the orientation function is 0.22 or more and 0.31 or less. By controlling the crystallization index and orientation function of the PVA-based resin layer after the air stretching process within the above range as described above, a polarizing film with thin thickness, small thickness variation and high optical characteristics can be manufactured.

空中延伸處理後之PVA系樹脂層之結晶化指數係用傅立葉轉換紅外光譜光度計(FT-IR)並以偏光作為測定光，藉由ATR測定來求得。具體而言，係於令測定偏光相對於延伸方向呈0°與90°之狀態下實施測定，並使用所得光譜之1141cm-1 及1140cm-1 的強度，依下述式算出。另外，1141cm-1 的強度與PVA系樹脂層的結晶部分之量具有相關性。 結晶化指數＝((IC-0 +2×IC-90 )/3)/((IR-0 +2×IR-90 )/3)惟， IC-0 ：將測定光(偏光)於與延伸方向平行之方向入射並進行測定時之1141cm-1 的強度 IC-90 ：將測定光(偏光)於與延伸方向垂直之方向入射並進行測定時之1141cm-1 的強度 IR-0 ：將測定光(偏光)於與延伸方向平行之方向入射並進行測定時之1140cm-1 的強度 IR-90 ：將測定光(偏光)於與延伸方向垂直之方向入射並進行測定時之1140cm-1 的強度The crystallization index of the PVA-based resin layer after the air stretching process was obtained by ATR measurement using a Fourier transform infrared spectrophotometer (FT-IR) and using polarized light as the measurement light. Specifically, based on the embodiments make a polarizing phase is measured at a state of 0 ° and 90 °, and using the intensity of 1141cm -1 and 1140cm -1 of the extending direction of the resultant spectrum, was calculated by the following equation. In addition, the strength of 1141 cm -1 has a correlation with the amount of crystal parts of the PVA-based resin layer. Crystallization index = ((I C-0 +2×I C-90 )/3)/((I R-0 +2×I R-90 )/3) However, I C-0 : will determine the light ( polarization) 1141cm -1 when the intensity of the direction parallel to the extending direction of the incident and measured I C-90: 1141cm -1 when the intensity of the measuring light (polarized light) in the incident direction perpendicular to the extending direction and measured I R-0 : The intensity of 1140 cm -1 when measuring light (polarized light) is incident in a direction parallel to the extending direction and measuring I R-90 : Measuring light (polarized light) is incident and measured in a direction perpendicular to the extending direction The intensity of 1140cm -1

空中延伸處理後之PVA系樹脂層的定向函數(f)例如係利用FT-IR並以偏光作為測定光，藉由ATR測定來求得。具體而言，係於令測定偏光相對於延伸方向呈0°與90°之狀態下實施測定，並使用所得光譜之2941cm-1 的強度，依下述式算出。在此，強度I係以3330cm-1 為參考峰值，而為2941cm-1 /3330cm-1 之值。另外，f＝1時為完全定向，f＝0時為無規。又，吾等認為2941cm-1 之峰值起因於PVA主鏈(-CH2-)之振動的吸收。 f＝(3>cos2 θ>-1)/2 ＝(1-D)/[c(2D+1)] 惟， c＝(3cos2 β-1)/2 β＝90deg⇒f＝-2×(1-D)/(2D+1) θ：分子鏈・延伸方向 β：分子鏈・偶極矩 D＝(I⊥)/(I//) (PVA分子越定向，D值越大) I⊥：將測定光(偏光)於與延伸方向垂直之方向入射並進行測定時的強度 I//：將測定光(偏光)於與延伸方向平行之方向入射並進行測定時的強度The orientation function (f) of the PVA-based resin layer after the air stretching process is obtained by ATR measurement using, for example, FT-IR and polarized light as measurement light. Specifically, the measurement is performed in a state where the measurement polarized light is at 0° and 90° with respect to the extending direction, and the intensity of 2941 cm -1 of the obtained spectrum is calculated according to the following formula. Here, the intensity I is a value that takes 3330 cm -1 as a reference peak and is 2941 cm -1 /3330 cm -1 . In addition, when f=1, it is fully oriented, and when f=0, it is random. In addition, we believe that the peak of 2941 cm -1 is due to the absorption of vibration of the PVA main chain (-CH2-). f=(3>cos 2 θ>-1)/2 =(1-D)/[c(2D+1)] However, c=(3cos 2 β-1)/2 β=90deg⇒f=-2 ×(1-D)/(2D+1) θ: molecular chain and extension direction β: molecular chain and dipole moment D = (I⊥)/(I//) (the more oriented the PVA molecule, the larger the D value) I⊥: Intensity when measuring light (polarized light) is incident in a direction perpendicular to the extending direction and measurement I//: Intensity when measuring light (polarized light) is incident in a direction parallel to the extending direction and measurement

B.偏光板 圖1係本發明之一實施形態之偏光板的概略截面圖。偏光板100具有：偏光膜10、配置於偏光膜10之一側的第1保護層20、及配置於偏光膜10之另一側的第2保護層30。偏光膜10係於上述A項所說明之本發明之偏光膜。亦可省略第1保護層20及第2保護層30之中其中一保護層。此外，第1保護層及第2保護層之中其中一者可為用於製造上述偏光膜之樹脂基材。B. Polarizer FIG. 1 is a schematic cross-sectional view of a polarizing plate according to an embodiment of the present invention. The polarizing plate 100 includes a polarizing film 10, a first protective layer 20 disposed on one side of the polarizing film 10, and a second protective layer 30 disposed on the other side of the polarizing film 10. The polarizing film 10 is the polarizing film of the present invention described in the above item A. One of the first protective layer 20 and the second protective layer 30 may be omitted. In addition, one of the first protective layer and the second protective layer may be a resin substrate used for manufacturing the polarizing film.

第1及第2保護薄膜係以可作為偏光膜之保護層使用的任意且適當的薄膜形成。作為該薄膜之主成分的材料之具體例，可舉出三乙醯纖維素(TAC)等之纖維素樹脂、聚酯系、聚乙烯醇系、聚碳酸酯系、聚醯胺系、聚醯亞胺系、聚醚碸系、聚碸系、聚苯乙烯系、聚降莰烯系、聚烯烴系、(甲基)丙烯酸系及乙酸酯系等之透明樹脂等。又，亦可舉出(甲基)丙烯酸系、胺甲酸酯系、(甲基)丙烯酸胺甲酸酯系、環氧系、聚矽氧系等熱硬化型樹脂或紫外線硬化型樹脂等。其他還可舉出例如矽氧烷系聚合物等之玻璃質系聚合物。並且，亦可使用日本專利特開2001-343529號公報(WO01/37007)所記載之聚合物薄膜。作為該薄膜之材料，例如可以使用含有在側鏈具有取代或非取代之醯亞胺基的熱塑性樹脂與在側鏈具有取代或非取代之苯基以及腈基的熱塑性樹脂之樹脂組成物，例如可舉出具有由異丁烯與N-甲基馬來醯亞胺構成之交替共聚物及丙烯腈-苯乙烯共聚物之樹脂組成物。該聚合物薄膜例如可為上述樹脂組成物之擠製成形物。The first and second protective films are formed of any suitable films that can be used as protective layers for polarizing films. Specific examples of the material of the main component of the film include cellulose resins such as triethyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, and polyacetyl Transparent resins such as imine-based, polyether-based, poly-based, polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic, and acetate-based. In addition, thermosetting resins such as (meth)acrylic system, urethane system, (meth)acrylate urethane system, epoxy system, and polysiloxane system, ultraviolet curing resin, etc. may also be mentioned. Other examples include glassy polymers such as siloxane-based polymers. Moreover, the polymer film described in Japanese Patent Laid-Open No. 2001-343529 (WO01/37007) can also be used. As the material of the film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted amide imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used, for example Examples thereof include resin compositions having an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer. The polymer film may be, for example, an extruded product of the above resin composition.

在將偏光板100應用於影像顯示裝置時，配置於與顯示面板相反之側的保護層(外側保護層)之厚度代表上為300μm以下，宜為100μm以下，更宜為5μm~80μm，又更宜為10μm~60μm。另外，在施有表面處理時，外側保護層之厚度係包含表面處理層之厚度。When the polarizing plate 100 is applied to an image display device, the thickness of the protective layer (outer protective layer) disposed on the side opposite to the display panel is typically 300 μm or less, preferably 100 μm or less, more preferably 5 μm to 80 μm, and more It should be 10μm~60μm. In addition, when surface treatment is applied, the thickness of the outer protective layer includes the thickness of the surface treatment layer.

在將偏光板100應用於影像顯示裝置時配置於顯示面板側的保護層(內側保護層)之厚度宜為5μm~200μm，更宜為10μm~100μm，又更宜為10μm~60μm。在一實施形態中，內側保護層係具有任意且適當之相位差值的相位差層。相位差層可使用具有面內相位差為40nm以上及/或厚度方向相位差為80nm以上之相位差的相位差薄膜。面內相位差通常係控制在40~200nm之範圍，厚度方向相位差通常係控制在80~300nm之範圍。作為相位差薄膜，可舉如將高分子素材進行單軸或雙軸延伸處理而成之雙折射性薄膜、液晶聚合物之定向薄膜、以薄膜支持液晶聚合物之定向層者等。相位差薄膜之厚度無特別限制，一般為20~150μm左右。When the polarizing plate 100 is applied to an image display device, the thickness of the protective layer (inside protective layer) disposed on the display panel side is preferably 5 μm to 200 μm, more preferably 10 μm to 100 μm, and still more preferably 10 μm to 60 μm. In one embodiment, the inner protective layer is a phase difference layer having an arbitrary and appropriate phase difference value. As the retardation layer, a retardation film having a retardation with an in-plane retardation of 40 nm or more and/or a thickness direction retardation of 80 nm or more can be used. The in-plane phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. Examples of the retardation film include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, an alignment film of liquid crystal polymer, and an alignment layer in which the film supports the liquid crystal polymer. The thickness of the retardation film is not particularly limited, and is generally about 20 to 150 μm.

C.偏光膜之製造方法 本發明一實施形態之偏光膜之製造方法如上述，包含以下步驟：於熱塑性樹脂基材之單側形成含聚乙烯醇系樹脂之聚乙烯醇系樹脂層，而製成積層體；及，對上述積層體依序施行空中延伸處理與染色處理。上述空中延伸處理後之上述聚乙烯醇系樹脂層利用衰減全反射分光測定算出之結晶化指數為1.55以上且1.7以下，且定向函數為0.22以上且0.31以下。較佳為：於空中延伸處理之後包含對積層體施行水中延伸處理；空中延伸處理之延伸倍率為3.0倍以上，且水中延伸處理之延伸倍率為1.8倍以下。依上所述，相較於以往之製造方法，將空中延伸處理之延伸倍率設定得較高，並將水中延伸處理之延伸倍率設定得較低，可促進空中延伸處理後之PVA系樹脂層結晶化，同時可抑制熱塑性樹脂基材過度結晶化。藉此可製得厚度參差小且具有優異光學特性之偏光膜。C. Manufacturing method of polarizing film The manufacturing method of the polarizing film according to an embodiment of the present invention is as described above and includes the following steps: forming a polyvinyl alcohol-based resin layer containing a polyvinyl alcohol-based resin on one side of the thermoplastic resin substrate to form a laminate; and, The above-mentioned layered body is sequentially subjected to aerial extension processing and dyeing processing. The polyvinyl alcohol-based resin layer after the air stretching process has a crystallization index calculated by attenuation total reflection spectrometry of 1.55 or more and 1.7 or less, and the orientation function is 0.22 or more and 0.31 or less. Preferably, after the aerial extension treatment, the underwater extension treatment is applied to the laminate; the aerial extension treatment has an extension ratio of 3.0 times or more, and the underwater extension treatment has an extension ratio of 1.8 times or less. As mentioned above, compared with the previous manufacturing method, setting the stretching magnification of the air stretching process to be higher, and setting the stretching magnification of the water stretching process to be lower, can promote the crystallization of the PVA-based resin layer after the air stretching process At the same time, excessive crystallization of the thermoplastic resin substrate can be suppressed. Thereby, a polarizing film with small thickness variation and excellent optical characteristics can be produced.

C-1.製作積層體 製作熱塑性樹脂基材與PVA系樹脂層之積層體的方法可採用任意且適當之方法。較宜為將含PVA系樹脂之塗佈液塗佈於長條狀熱塑性樹脂基材之表面並乾燥，藉此於熱塑性樹脂基材上形成PVA系樹脂層。C-1. Making a laminate As a method for producing a laminate of a thermoplastic resin base material and a PVA-based resin layer, any suitable method can be adopted. It is more preferable to apply a coating solution containing a PVA-based resin to the surface of a long thermoplastic resin substrate and dry it, thereby forming a PVA-based resin layer on the thermoplastic resin substrate.

塗佈液之塗佈方法可採用任意且適當的方法。例如可舉出輥塗法、旋塗法、線棒塗佈法、浸塗法、模塗法、淋幕式塗佈法、噴塗法、刮刀式塗佈法(逗號塗佈法等)等。上述塗佈液之塗佈、乾燥溫度宜為50℃以上。The method for applying the coating liquid can be any appropriate method. For example, a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, a doctor blade coating method (comma coating method, etc.), etc. are mentioned. The coating and drying temperature of the coating liquid is preferably 50°C or higher.

PVA系樹脂層之厚度宜為3μm~40μm，更宜為3μm~20μm。The thickness of the PVA-based resin layer is preferably 3 μm to 40 μm, and more preferably 3 μm to 20 μm.

在形成PVA系樹脂層之前，可對熱塑性樹脂基材施行表面處理(例如電暈處理等)，也可於熱塑性樹脂基材上形成易接著層。藉由進行所述處理，可提升熱塑性樹脂基材與PVA系樹脂層之密著性。Before forming the PVA-based resin layer, the thermoplastic resin substrate may be subjected to surface treatment (for example, corona treatment, etc.), or an easy adhesion layer may be formed on the thermoplastic resin substrate. By performing the treatment, the adhesion between the thermoplastic resin base material and the PVA-based resin layer can be improved.

C-1-1.熱塑性樹脂基材 熱塑性樹脂基材之厚度宜為20μm~300μm，更宜為50μm~200μm。若小於20μm，恐難以形成PVA系樹脂層。若大於300μm，譬如恐有在後述水中延伸處理時，熱塑性樹脂基材需要較長時間來吸水且還會對延伸造成過大的負荷之虞。C-1-1. Thermoplastic resin substrate The thickness of the thermoplastic resin substrate is preferably 20 μm to 300 μm, more preferably 50 μm to 200 μm. If it is less than 20 μm, it may be difficult to form a PVA-based resin layer. If it is greater than 300 μm, for example, there is a possibility that the thermoplastic resin substrate may take a long time to absorb water when it is stretched in water, which will be described later, and may cause excessive load on the stretch.

熱塑性樹脂基材之吸水率宜為0.2%以上，更宜為0.3%以上。熱塑性樹脂基材吸水，水可發揮塑化劑的作用進行塑化。結果可大幅降低延伸應力而可高倍率地延伸。另一方面，熱塑性樹脂基材之吸水率宜為3.0%以下，更宜為1.0%以下。藉由使用所述熱塑性樹脂基材，可防止製造時熱塑性樹脂基材的尺寸穩定性顯著降低而造成所製得之偏光膜的外觀惡化等不良情況。並可防止基材於水中延伸時斷裂、或PVA系樹脂層從熱塑性樹脂基材剝離之情況。另外，熱塑性樹脂基材之吸水率，舉例而言可藉由將改質基導入構成材料中來調整。吸水率係按JIS K 7209所求得之值。The water absorption rate of the thermoplastic resin substrate is preferably 0.2% or more, and more preferably 0.3% or more. The thermoplastic resin substrate absorbs water, and water can play the role of a plasticizer for plasticization. As a result, the extension stress can be greatly reduced and the extension can be performed at a high rate. On the other hand, the water absorption rate of the thermoplastic resin substrate is preferably 3.0% or less, and more preferably 1.0% or less. By using the thermoplastic resin base material, it is possible to prevent the dimensional stability of the thermoplastic resin base material from being significantly reduced during manufacturing, which may cause defects such as deterioration of the appearance of the polarizing film produced. It can prevent the base material from breaking when extending in water, or the PVA-based resin layer peeling off from the thermoplastic resin base material. In addition, the water absorption rate of the thermoplastic resin base material can be adjusted by, for example, introducing a modified group into the constituent material. The water absorption rate is a value determined in accordance with JIS K 7209.

熱塑性樹脂基材之玻璃轉移溫度(Tg)宜為120℃以下。藉由使用所述熱塑性樹脂基材，可抑制PVA系樹脂層之結晶化，同時充分確保積層體之延伸性。另外，考慮到利用水使熱塑性樹脂基材塑化與可良好進行水中延伸，以100℃以下、更以90℃以下更佳。另一方面，熱塑性樹脂基材之玻璃轉移溫度宜為60℃以上。藉由使用所述熱塑性樹脂基材，可防止在塗佈、乾燥包含上述PVA系樹脂之塗佈液時，發生熱塑性樹脂基材變形(發生例如凹凸、垂塌或起皺等)等不良情況，從而良好地製作出積層體。又，可在適當的溫度(例如60℃左右)下良好地進行PVA系樹脂層的延伸。另外，熱塑性樹脂基材之玻璃轉移溫度，舉例而言可藉由使用可將改質基導入構成材料之結晶化材料進行加熱來調整。玻璃轉移溫度(Tg)是依據JIS K 7121求出之值。The glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 120°C or lower. By using the thermoplastic resin base material, it is possible to suppress the crystallization of the PVA-based resin layer while sufficiently ensuring the extensibility of the laminate. In addition, in consideration of plasticizing the thermoplastic resin base material with water and allowing good water extension, it is preferably 100°C or lower, more preferably 90°C or lower. On the other hand, the glass transition temperature of the thermoplastic resin substrate is preferably 60°C or higher. By using the thermoplastic resin substrate, it is possible to prevent defects such as deformation of the thermoplastic resin substrate (e.g., unevenness, sag, wrinkle, etc.) when applying and drying the coating solution containing the PVA-based resin. As a result, the laminate is produced satisfactorily. In addition, the PVA-based resin layer can be stretched well at an appropriate temperature (for example, about 60°C). In addition, the glass transition temperature of the thermoplastic resin substrate can be adjusted by, for example, heating by using a crystallization material that can introduce a modified group into the constituent material. The glass transition temperature (Tg) is a value determined in accordance with JIS K 7121.

熱塑性樹脂基材之構成材料可採用任意且適當的熱塑性樹脂。熱塑性樹脂可舉例如聚對苯二甲酸乙二酯系樹脂等酯系樹脂、降莰烯系樹脂等環烯烴系樹脂、聚丙烯等烯烴系樹脂、聚醯胺系樹脂、聚碳酸酯系樹脂及其等之共聚物樹脂等。這些當中，較理想的是降莰烯系樹脂、非晶質之聚對苯二甲酸乙二酯系樹脂。As the constituent material of the thermoplastic resin base material, any suitable thermoplastic resin can be used. Examples of thermoplastic resins include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins and Copolymer resins, etc. Among these, norbornene-based resins and amorphous polyethylene terephthalate-based resins are more desirable.

在一實施形態中，宜使用非晶質之(未結晶化之)聚對苯二甲酸乙二酯系樹脂。其中，尤宜使用非晶性之(難以結晶化之)聚對苯二甲酸乙二酯系樹脂。非晶性之聚對苯二甲酸乙二酯系樹脂之具體例，可舉更含有作為二羧酸之異酞酸及/或環己烷二羧酸的共聚物、或是更含有作為甘醇之環己烷二甲醇或二乙二醇的共聚物。In one embodiment, an amorphous (uncrystallized) polyethylene terephthalate resin is preferably used. Among them, the use of amorphous (difficult to crystallize) polyethylene terephthalate resins is particularly preferred. Specific examples of the amorphous polyethylene terephthalate-based resin include a copolymer of isophthalic acid and/or cyclohexane dicarboxylic acid as a dicarboxylic acid, or glycol as a glycol The copolymer of cyclohexane dimethanol or diethylene glycol.

在較佳之實施形態中，熱塑性樹脂基材係由具有異酞酸單元之聚對苯二甲酸乙二酯系樹脂所構成。其係因所述熱塑性樹脂基材具有極優異的延伸性並且可抑制延伸時之結晶化之故。吾等推測其是透過導入異酞酸單元而賦予主鏈巨大的撓曲所致。聚對苯二甲酸乙二酯系樹脂具有對苯二甲酸單元及乙二醇單元。異酞酸單元之含有比率，相對於全部重複單元之合計宜為0.1莫耳%以上，更宜為1.0莫耳%以上。其係因可製得具有極優異延伸性之熱塑性樹脂基材之故。另一方面，異酞酸單元之含有比率，相對於全部重複單元之合計宜為20莫耳%以下，更宜為10莫耳%以下。藉由設定成所述含有比率，可在後述之乾燥收縮處理中良好地增加結晶化度。In a preferred embodiment, the thermoplastic resin substrate is composed of a polyethylene terephthalate resin having isophthalic acid units. This is because the thermoplastic resin substrate has extremely excellent extensibility and can suppress crystallization during elongation. We speculate that it is caused by the introduction of isophthalic acid units to give the main chain a huge deflection. The polyethylene terephthalate-based resin has terephthalic acid units and ethylene glycol units. The content ratio of isophthalic acid units is preferably 0.1 mol% or more, and more preferably 1.0 mol% or more relative to the total of all repeating units. This is because a thermoplastic resin substrate with extremely excellent elongation can be produced. On the other hand, the content ratio of the isophthalic acid unit is preferably 20 mol% or less, and more preferably 10 mol% or less with respect to the total of all repeating units. By setting the content ratio, the degree of crystallization can be favorably increased in the drying shrinkage treatment described later.

熱塑性樹脂基材亦可已預先(在形成PVA系樹脂層前)進行延伸。在一實施形態中，係經已於長條狀熱塑性樹脂基材之橫向延伸。橫向宜為與後述積層體之延伸方向正交的方向。另，本說明書中所謂「正交」亦包含實質上正交之情形。於此，「實質上正交」包含90°±5.0°之情況，宜為90°±3.0°，更宜為90°±1.0°。熱塑性樹脂基材之延伸溫度相對於玻璃轉移溫度(Tg)宜為Tg-10℃~Tg+50℃。熱塑性樹脂基材之延伸倍率宜為1.5倍~3.0倍。熱塑性樹脂基材之延伸方法可採用任意且適當之方法。具體而言，可為固定端延伸，亦可為自由端延伸。延伸方式可為乾式亦可為濕式。熱塑性樹脂基材之延伸可在一階段中進行亦可分多階段進行。分多階段進行時，上述延伸倍率為各階段之延伸倍率之積。The thermoplastic resin base material may have been stretched in advance (before the PVA-based resin layer is formed). In one embodiment, it has been extended in the lateral direction of the long thermoplastic resin substrate. The lateral direction is preferably a direction orthogonal to the extending direction of the laminate to be described later. In addition, the term "orthogonal" in this specification also includes the case where it is substantially orthogonal. Here, "substantially orthogonal" includes 90°±5.0°, preferably 90°±3.0°, more preferably 90°±1.0°. The extension temperature of the thermoplastic resin substrate relative to the glass transition temperature (Tg) is preferably Tg-10°C~Tg+50°C. The extension ratio of the thermoplastic resin substrate is preferably 1.5 times to 3.0 times. As for the method of stretching the thermoplastic resin substrate, any suitable method can be adopted. Specifically, it may be a fixed end or a free end. The extension method can be dry or wet. The extension of the thermoplastic resin substrate can be performed in one stage or in multiple stages. When performing in multiple stages, the above-mentioned stretching magnification is the product of the stretching magnifications in each stage.

C-1-2.塗佈液 塗佈液代表上係已使上述PVA系樹脂溶解於溶劑中之溶液。作為溶劑，可舉例如水、二甲亞碸、二甲基甲醯胺、二甲基乙醯胺、N-甲基吡咯啶酮、各種甘醇類、三羥甲丙烷等多元醇類、伸乙二胺、二伸乙三胺等胺類。該等可單獨使用或可將二種以上組合使用。該等中又以水為佳。溶液之PVA系樹脂濃度相對於溶劑100重量份宜為3重量份~20重量份。只要為所述樹脂濃度，便可形成密著於熱塑性樹脂基材且均勻的塗佈膜。C-1-2. Coating liquid The coating liquid represents a solution in which the above PVA-based resin has been dissolved in a solvent. Examples of the solvent include polyhydric alcohols such as water, dimethylsulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, and trimethylolpropane. Diamines, diethylenetriamine and other amines. These can be used alone or in combination of two or more. Among these, water is better. The concentration of the PVA resin in the solution is preferably 3 to 20 parts by weight relative to 100 parts by weight of the solvent. As long as it is the resin concentration, a uniform coating film adhered to the thermoplastic resin substrate can be formed.

塗佈液中亦可摻混添加劑。添加劑可舉如塑化劑、界面活性劑等。塑化劑可舉例如乙二醇或丙三醇等多元醇。界面活性劑可舉例如非離子性界面活性劑。該等可為了進一步提升所得PVA系樹脂層的均勻性或染色性、延伸性而使用。Additives can also be incorporated in the coating solution. Examples of additives include plasticizers and surfactants. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin. The surfactant may, for example, be a nonionic surfactant. These can be used to further improve the uniformity, dyeability, and extensibility of the resulting PVA-based resin layer.

上述PVA系樹脂可採用任意且適當的樹脂。可舉例如聚乙烯醇及乙烯-乙烯醇共聚物。聚乙烯醇可藉由將聚乙酸乙烯酯皂化而得。乙烯-乙烯醇共聚物可藉由將乙烯-乙酸乙烯酯共聚物皂化而得。PVA系樹脂之皂化度通常為85莫耳%~100莫耳%，宜為95.0莫耳%~99.95莫耳%，更宜為99.0莫耳%~99.93莫耳%。皂化度係依JIS K 6726-1994而求得。藉由使用所述皂化度的PVA系樹脂，可獲得耐久性優異的偏光膜。皂化度太高時，會有膠化之虞。Any appropriate resin can be used for the PVA-based resin. Examples thereof include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer can be obtained by saponifying the ethylene-vinyl acetate copolymer. The saponification degree of the PVA resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, and more preferably 99.0 mol% to 99.93 mol%. The degree of saponification is determined in accordance with JIS K 6726-1994. By using the saponification degree PVA-based resin, a polarizing film excellent in durability can be obtained. When the degree of saponification is too high, there is a risk of gelation.

PVA系樹脂的平均聚合度可按目的適當選擇。平均聚合度通常為1000~10000，宜為1200~4500，更宜為1500~4300。另，平均聚合度可按JIS K 6726-1994而求得。The average degree of polymerization of the PVA-based resin can be appropriately selected according to the purpose. The average polymerization degree is usually 1000 to 10000, preferably 1200 to 4500, and more preferably 1500 to 4300. In addition, the average degree of polymerization can be obtained in accordance with JIS K 6726-1994.

C-2.空中輔助延伸處理 空中延伸處理之延伸倍率宜為3.0倍~4.0倍。藉此可將空中延伸處理後之PVA系樹脂層的結晶化指數及定向函數控制在期望之數值範圍內。並且，依所述，相較於以往之製造方法，藉由將空中延伸處理之延伸倍率設定得較高，可將用以在後述之水中延伸處理中實現期望之光學特性的延伸倍率設定得較低。藉此，可抑制水中延伸處理造成熱塑性樹脂基材過度結晶化。C-2. Air-assisted extension processing The extension magnification of the air extension processing should be 3.0 times to 4.0 times. In this way, the crystallization index and orientation function of the PVA-based resin layer after the air stretching process can be controlled within a desired value range. In addition, according to the above, by setting the extension magnification of the aerial stretching process to be higher than that of the conventional manufacturing method, the extension magnification used to achieve the desired optical characteristics in the underwater stretching process to be described later can be set to a higher low. Thereby, excessive crystallization of the thermoplastic resin base material caused by the extension treatment in water can be suppressed.

空中輔助延伸之延伸方法可為固定端延伸(例如使用拉幅延伸機進行延伸之方法)，亦可為自由端延伸(例如使積層體通過周速相異之輥間進行單軸延伸之方法)，惟為了獲得高光學特性，可積極採用自由端延伸。在一實施形態中，空中延伸處理包含加熱輥延伸步驟，該步驟係將長條狀之上述積層體往其長邊方向輸送並同時利用加熱輥間之周速差進行延伸。空中延伸處理在代表上係包含區域(zone)延伸步驟與加熱輥延伸步驟。另，區域延伸步驟與加熱輥延伸步驟之順序並無限定，可先進行區域延伸步驟，亦可先進行加熱輥延伸步驟。亦可省略區域延伸步驟。在一實施形態中，係依序進行區域延伸步驟及加熱輥延伸步驟。又，在另一實施形態中，係於拉幅延伸機中把持薄膜端部，並將拉幅機間之距離往行進方向擴大來進行延伸(拉幅機間距離的增幅即為延伸倍率)。此時，寬度方向(相對於行進方向為垂直方向)之拉幅機的距離係設定成可任意接近。較佳可設定成相對於行進方向之延伸倍率來利用自由端延伸作接近。為自由端延伸時，係以寬度方向之收縮率=(1/延伸倍率)1/2 來計算。The extension method of air-assisted extension can be fixed-end extension (such as the method of using a tenter stretching machine) or free-end extension (such as the method of uniaxially extending the laminate through rollers with different peripheral speeds) However, in order to obtain high optical characteristics, the free end extension can be actively used. In one embodiment, the aerial stretching process includes a heating roller stretching step that conveys the above-mentioned long laminate in the longitudinal direction and at the same time stretches using the circumferential speed difference between the heating rollers. The air stretching process typically includes a zone stretching step and a heating roller stretching step. In addition, the order of the region stretching step and the heating roller stretching step is not limited, and the region stretching step may be performed first, or the heating roller stretching step may be performed first. The region extension step can also be omitted. In one embodiment, the region extending step and the heating roller extending step are performed in sequence. Furthermore, in another embodiment, the end of the film is held in a tenter stretching machine, and the distance between the tenter machines is expanded in the direction of travel to extend (the increase in the distance between the tenter machines is the stretching ratio). At this time, the distance of the tenter in the width direction (perpendicular to the traveling direction) is set to be arbitrarily close. Preferably, it can be set to an extension magnification relative to the direction of travel to use free-end extension for approach. When the free end is extended, it is calculated as the shrinkage ratio in the width direction = (1/extension ratio) 1/2 .

空中輔助延伸可在一階段中進行亦可分多階段進行。分多階段進行時，延伸倍率為各階段之延伸倍率之積。空中輔助延伸中之延伸方向宜與水中延伸之延伸方向大致相同。The air-assisted extension can be performed in one stage or in multiple stages. When carried out in multiple stages, the stretching magnification is the product of the stretching magnifications in each stage. The extension direction of the air-assisted extension should be approximately the same as the extension direction of the underwater extension.

組合空中輔助延伸與水中延伸時之最大延伸倍率，相對於積層體原長以5.0倍以上為宜，以5.5倍以上為佳，以6.0倍以上為更佳。本說明書中「最大延伸倍率」意指積層體將要斷裂前的延伸倍率，係另外確認積層體斷裂的延伸倍率後得以比其值低0.2之值。The maximum extension magnification when combining air-assisted extension and underwater extension is preferably 5.0 times or more relative to the original length of the laminate, preferably 5.5 times or more, and more preferably 6.0 times or more. The "maximum elongation ratio" in this specification means the elongation ratio before the laminate is to be broken, and it is a value that is 0.2 lower than its value after confirming the elongation ratio of the laminate to break.

空中輔助延伸之延伸溫度可因應熱塑性樹脂基材之形成材料、延伸方式等設定成任意且適當之值。延伸溫度宜為熱塑性樹脂基材之玻璃轉移溫度(Tg)以上，而熱塑性樹脂基材之玻璃轉移溫度(Tg)+10℃以上更適宜，Tg+15℃以上特別適宜。另一方面，延伸溫度的上限宜為170℃。在所述溫度下延伸可抑制PVA系樹脂之結晶化快速進展，從而可抑制該結晶化所造成的不良情況(譬如，因延伸而妨礙PVA系樹脂層之定向)。The extension temperature of the air-assisted extension can be set to an arbitrary and appropriate value according to the forming material of the thermoplastic resin base material, the extension method, and the like. The elongation temperature is preferably higher than the glass transition temperature (Tg) of the thermoplastic resin substrate, and more preferably the glass transition temperature (Tg) of the thermoplastic resin substrate + 10°C or higher, and particularly preferably Tg + 15°C or higher. On the other hand, the upper limit of the extension temperature is preferably 170°C. Elongation at the above-mentioned temperature can suppress the rapid progress of crystallization of the PVA-based resin, thereby suppressing the disadvantages caused by the crystallization (for example, hindering the orientation of the PVA-based resin layer due to extension).

C-3.不溶解處理 視需要在空中輔助延伸處理之後且在水中延伸處理或染色處理之前，施行不溶解處理。上述不溶解處理代表上係將PVA系樹脂層浸漬於硼酸水溶液中來進行。藉由施行不溶解處理，可賦予PVA系樹脂層耐水性，防止浸漬於水中時PVA之定向降低。該硼酸水溶液之濃度相對於水100重量份宜為1重量份~4重量份。不溶解浴(硼酸水溶液)之液溫宜為20℃~50℃。C-3. Insoluble treatment If necessary, after the air-assisted extension treatment and before the water extension treatment or dyeing treatment, the insolubilization treatment is performed. The above-mentioned insolubilization treatment represents that the PVA-based resin layer is immersed in a boric acid aqueous solution. By performing the insolubilization treatment, the PVA-based resin layer can be given water resistance, and the orientation of the PVA can be prevented from decreasing when immersed in water. The concentration of the boric acid aqueous solution is preferably 1 part by weight to 4 parts by weight relative to 100 parts by weight of water. The liquid temperature of the insoluble bath (boric acid aqueous solution) is preferably 20°C to 50°C.

C-4.染色處理 上述染色處理代表上係以碘將PVA系樹脂層染色來進行。具體上係藉由使碘吸附於PVA系樹脂層來進行。該吸附方法可舉如：使PVA系樹脂層(積層體)浸漬於含碘之染色液中的方法、將該染色液塗敷於PVA系樹脂層上的方法、及將該染色液噴霧至PVA系樹脂層上的方法等。宜採用使積層體浸漬於染色液(染色浴)中的方法。其是因為可良好吸附碘之故。C-4. Dyeing treatment The above-mentioned dyeing treatment represents that the PVA-based resin layer is dyed with iodine on the upper system. Specifically, it is performed by adsorbing iodine to the PVA-based resin layer. Examples of the adsorption method include a method of immersing the PVA-based resin layer (laminate) in a dyeing solution containing iodine, a method of applying the dyeing solution to the PVA-based resin layer, and spraying the dyeing solution to the PVA Method on the resin layer. The method of immersing the laminate in the dyeing liquid (dyeing bath) is preferably used. This is because it can adsorb iodine well.

上述染色液宜為碘水溶液。碘之摻混量相對於水100重量份宜為0.05重量份~0.5重量份。為了提高碘對水的溶解度，宜於碘水溶液中摻混碘化物。碘化物可舉出例如：碘化鉀、碘化鋰、碘化鈉、碘化鋅、碘化鋁、碘化鉛、碘化銅、碘化鋇、碘化鈣、碘化錫、碘化鈦等。該等之中又以碘化鉀為佳。碘化物之摻混量相對於水100重量份宜為0.1重量份~10重量份，較宜為0.3重量份~5重量份。為了抑制PVA系樹脂溶解，染色液於染色時的液溫宜為20℃~50℃。使PVA系樹脂層浸漬於染色液時，為了確保PVA系樹脂層之透射率，浸漬時間宜為5秒~5分鐘，且30秒~90秒更佳。The above dyeing solution is preferably an aqueous iodine solution. The blending amount of iodine is preferably 0.05 to 0.5 parts by weight relative to 100 parts by weight of water. In order to improve the solubility of iodine in water, it is appropriate to mix iodide in the iodine aqueous solution. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Among these, potassium iodide is preferred. The blending amount of the iodide is preferably 0.1 to 10 parts by weight, and more preferably 0.3 to 5 parts by weight relative to 100 parts by weight of water. In order to suppress the dissolution of the PVA-based resin, the temperature of the dyeing liquid during dyeing is preferably 20°C to 50°C. When immersing the PVA-based resin layer in the dyeing solution, in order to ensure the transmittance of the PVA-based resin layer, the immersion time is preferably 5 seconds to 5 minutes, and more preferably 30 seconds to 90 seconds.

染色條件(濃度、液溫、浸漬時間)可設定成以使最後所得偏光膜之偏光度或單體透射率成為預定範圍內。在一實施形態中係以所得偏光膜之單體透射率成為44.5%~45.0%的方式來設定浸漬時間。在另一實施形態中係以使所得偏光膜之偏光度成為99.0%以上的方式來設定浸漬時間。The dyeing conditions (concentration, liquid temperature, immersion time) can be set so that the polarization degree or monomer transmittance of the polarizing film finally obtained is within a predetermined range. In one embodiment, the immersion time is set such that the monomer transmittance of the obtained polarizing film becomes 44.5% to 45.0%. In another embodiment, the immersion time is set so that the polarization degree of the obtained polarizing film becomes 99.0% or more.

在將積層體浸漬於含有硼酸之處理浴中的處理(代表上為不溶解處理)之後接續進行染色處理時，該處理浴中所含之硼酸會混入染色浴中而染色浴之硼酸濃度會隨時間變化，結果會有染色性變得不穩定之情形。為了抑制如上述之染色性的不穩定化，染色浴之硼酸濃度的上限係調整成相對於水100重量份宜為4重量份，更宜調整成2重量份。另一方面，染色浴之硼酸濃度的下限相對於水100重量份宜為0.1重量份，更宜為0.2重量份，又更宜為0.5重量份。在一實施形態中，係使用預先摻混有硼酸之染色浴來進行染色處理。藉此，可減低上述處理浴之硼酸混入染色浴中時硼酸濃度變化之比率。預先摻混至染色浴中的硼酸之摻混量(亦即非來自於上述處理浴之硼酸的含量)，相對於水100重量份宜為0.1重量份~2重量份，更宜為0.5重量份~1.5重量份。When the layered body is immersed in a treatment bath containing boric acid (typically insoluble treatment) and then dyeing is carried out, the boric acid contained in the treatment bath will be mixed into the dyeing bath and the concentration of boric acid in the dyeing bath will vary with the As time changes, as a result, the dyeability becomes unstable. In order to suppress the above-mentioned destabilization of the dyeing property, the upper limit of the boric acid concentration of the dyeing bath is adjusted to 4 parts by weight relative to 100 parts by weight of water, more preferably to 2 parts by weight. On the other hand, the lower limit of the boric acid concentration of the dyeing bath is preferably 0.1 part by weight, more preferably 0.2 part by weight, and still more preferably 0.5 part by weight with respect to 100 parts by weight of water. In one embodiment, the dyeing process is carried out using a dyeing bath premixed with boric acid. In this way, the ratio of the change in boric acid concentration when the boric acid in the treatment bath is mixed into the dyeing bath can be reduced. The amount of boric acid blended into the dyeing bath in advance (that is, the content of boric acid not derived from the above treatment bath) is preferably 0.1 to 2 parts by weight, more preferably 0.5 parts by weight relative to 100 parts by weight of water ~1.5 parts by weight.

C-5.交聯處理 視需要在染色處理之後且在水中延伸處理之前，施行交聯處理。上述交聯處理代表上可藉由使PVA系樹脂層浸漬於硼酸水溶液中來進行。藉由施行交聯處理，可賦予PVA系樹脂層耐水性，防止在之後的水中延伸中浸漬於高溫的水中時PVA之定向降低。該硼酸水溶液之濃度相對於水100重量份宜為1重量份~5重量份。又，於上述染色處理後進行交聯處理時，宜進一步摻混碘化物。藉由摻混碘化物，可抑制已吸附於PVA系樹脂層之碘的溶出。碘化物之摻混量相對於水100重量份宜為1重量份~5重量份。碘化物之具體例係如上述。交聯浴(硼酸水溶液)之液溫宜為20℃~50℃。C-5. Cross-linking treatment If necessary, cross-linking treatment is performed after the dyeing treatment and before the extension treatment in water. The above-mentioned cross-linking treatment can be performed by immersing the PVA-based resin layer in an aqueous solution of boric acid. By performing the cross-linking treatment, the PVA-based resin layer can be provided with water resistance, and the orientation of the PVA can be prevented from decreasing when immersed in high-temperature water during subsequent water stretching. The concentration of the boric acid aqueous solution is preferably 1 part by weight to 5 parts by weight relative to 100 parts by weight of water. In addition, when the cross-linking treatment is performed after the above-mentioned dyeing treatment, it is preferable to further blend iodide. By blending iodide, the elution of iodine that has been adsorbed on the PVA-based resin layer can be suppressed. The blending amount of iodide is preferably 1 part by weight to 5 parts by weight relative to 100 parts by weight of water. Specific examples of iodide are as described above. The liquid temperature of the cross-linking bath (boric acid aqueous solution) is preferably 20°C to 50°C.

C-6.水中延伸處理 水中延伸處理之延伸倍率宜為1.8倍以下，較佳為1.5倍以下。藉此，可抑制水中延伸處理造成熱塑性樹脂基材過度結晶化。並且可實現組合了空中輔助延伸時的高總延伸倍率，而可製造出光學特性極優異的偏光膜。C-6. Extended water treatment The extension magnification in the water extension treatment is preferably 1.8 times or less, preferably 1.5 times or less. Thereby, excessive crystallization of the thermoplastic resin base material caused by the extension treatment in water can be suppressed. In addition, a high total stretching magnification when combined with air-assisted stretching can be realized, and a polarizing film with extremely excellent optical characteristics can be manufactured.

水中延伸處理係使積層體浸漬於延伸浴來進行。藉由水中延伸處理，可在比上述熱塑性樹脂基材或PVA系樹脂層之玻璃轉移溫度(代表上為80℃左右)更低的溫度下延伸，而可在抑制PVA系樹脂層結晶化的同時進行高倍率延伸。結果可製出具有優異光學特性之偏光膜。The underwater stretching treatment is performed by immersing the laminate in the stretching bath. By water stretching, it can be stretched at a temperature lower than the glass transition temperature of the thermoplastic resin substrate or PVA-based resin layer (typically around 80°C), while suppressing crystallization of the PVA-based resin layer Perform high magnification extension. As a result, a polarizing film having excellent optical characteristics can be produced.

積層體之延伸方法可採用任意且適當的方法。具體而言，可為固定端延伸，亦可為自由端延伸(例如使積層體通過周速相異之輥間進行單軸延伸的方法)。較佳為選擇自由端延伸。積層體之延伸可在一階段中進行亦可分多階段進行。分多階段進行時，後述積層體之延伸倍率(最大延伸倍率)為各階段之延伸倍率之積。The method of extending the laminate can be any suitable method. Specifically, it may be a fixed-end extension or a free-end extension (for example, a method of uniaxially extending a laminate between rollers having different peripheral speeds). Preferably, the free end extension is selected. The extension of the laminate can be performed in one stage or in multiple stages. When performing in multiple stages, the stretching magnification (maximum stretching magnification) of the laminate to be described later is the product of the stretching magnification in each stage.

水中延伸宜使積層體浸漬於硼酸水溶液中來進行(硼酸水中延伸)。藉由使用硼酸水溶液作為延伸浴，可對PVA系樹脂層賦予得以承受延伸時所受張力的剛性與不溶於水的耐水性。具體上，硼酸在水溶液中會生成四羥基硼酸陰離子而可藉由氫鍵與PVA系樹脂交聯。結果可賦予PVA系樹脂層剛性與耐水性，進行良好地延伸，從而製出具有優異光學特性之偏光膜。The extension in water is preferably carried out by immersing the laminate in an aqueous solution of boric acid (boric acid extension in water). By using an aqueous solution of boric acid as an extension bath, the PVA-based resin layer can be given rigidity to withstand tension during extension and water resistance insoluble in water. Specifically, boric acid generates tetrahydroxyboric acid anions in the aqueous solution and can be cross-linked with the PVA-based resin by hydrogen bonding. As a result, it is possible to impart rigidity and water resistance to the PVA-based resin layer and perform good stretching, thereby producing a polarizing film having excellent optical characteristics.

上述硼酸水溶液宜使硼酸及/或硼酸鹽溶解於屬溶劑的水而獲得。另一方面，硼酸濃度相對於水100重量份宜為1重量份~10重量份，更宜為2.5重量份~6重量份，尤宜為3重量份~5重量份。藉由將硼酸濃度設為1重量份以上，可有效抑制PVA系樹脂層之溶解，製造特性更高之偏光膜。此外，除硼酸或硼酸鹽外，還可使用將硼砂等之硼化合物、乙二醛、戊二醛等溶解於溶劑而得之水溶液。The aforementioned boric acid aqueous solution is preferably obtained by dissolving boric acid and/or borate in water which is a solvent. On the other hand, the boric acid concentration is preferably 1 part by weight to 10 parts by weight relative to 100 parts by weight of water, more preferably 2.5 parts by weight to 6 parts by weight, and particularly preferably 3 parts by weight to 5 parts by weight. By setting the concentration of boric acid to 1 part by weight or more, the dissolution of the PVA-based resin layer can be effectively suppressed, and a polarizing film with higher characteristics can be manufactured. In addition to boric acid or borate, an aqueous solution obtained by dissolving boron compounds such as borax, glyoxal, glutaraldehyde and the like in a solvent can also be used.

宜於上述延伸浴(硼酸水溶液)中摻混碘化物。藉由摻混碘化物，可抑制已吸附於PVA系樹脂層之碘的溶出。碘化物之具體例如上述。碘化物之濃度相對於水100重量份宜為0.05重量份~15重量份，更宜為0.5重量份~8重量份。It is suitable to blend iodide in the above extension bath (boric acid aqueous solution). By blending iodide, the elution of iodine that has been adsorbed on the PVA-based resin layer can be suppressed. Specific examples of the iodide are mentioned above. The concentration of iodide relative to 100 parts by weight of water is preferably 0.05 to 15 parts by weight, more preferably 0.5 to 8 parts by weight.

延伸溫度(延伸浴之液溫)宜為40℃~85℃，較宜為60℃~75℃。只要為所述溫度，便可抑制PVA系樹脂層溶解，同時可高倍率地延伸。具體而言如上所述，若考量與形成PVA系樹脂層之關係，熱塑性樹脂基材之玻璃轉移溫度(Tg)以60℃以上為宜。此時，延伸溫度若低於40℃，則即使考慮以水將熱塑性樹脂基材塑化，也恐無法良好地延伸。另一方面，延伸浴之溫度愈高溫，PVA系樹脂層之溶解性就愈高，而恐無法獲得優異的光學特性。積層體浸漬於延伸浴之浸漬時間宜為15秒~5分鐘。The extension temperature (the liquid temperature of the extension bath) is preferably 40°C to 85°C, and more preferably 60°C to 75°C. As long as it is the above temperature, it is possible to suppress the dissolution of the PVA-based resin layer and to extend at a high rate. Specifically, as described above, considering the relationship with the formation of the PVA-based resin layer, the glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 60° C. or higher. At this time, if the stretching temperature is lower than 40°C, even if the thermoplastic resin base material is considered to be plasticized with water, it may not be stretched well. On the other hand, the higher the temperature of the stretching bath, the higher the solubility of the PVA-based resin layer, and it may be impossible to obtain excellent optical characteristics. The immersion time of the laminate in the extension bath is preferably 15 seconds to 5 minutes.

C-7.乾燥處理 上述乾燥處理可透過將區域整體加熱所進行之區域加熱來進行，亦可透過將輸送輥加熱(所謂使用加熱輥)來進行(加熱輥乾燥方式)。較佳為使用這兩者。藉由使用加熱輥使其乾燥，可有效率地抑制積層體之加熱捲曲，而製造出外觀優異的偏光膜。具體而言，藉由在使積層體沿著加熱輥之狀態下進行乾燥，可有效率地促進上述熱塑性樹脂基材之結晶化而增加結晶化度，即使是在相對較低的乾燥溫度下，仍能良好地增加熱塑性樹脂基材之結晶化度。結果熱塑性樹脂基材之剛性會增加而成為得以承受PVA系樹脂層因乾燥而收縮的狀態，從而捲曲受到抑制。又，藉由使用加熱輥，可在將積層體維持平坦狀態的同時進行乾燥，因此不只能抑制捲曲的產生，還能抑制起皺的產生。此時，積層體可透過乾燥收縮處理使其於寬度方向收縮，來提升光學特性。其係因可有效提升PVA及PVA/碘錯合物之定向性之故。C-7. Drying The above-mentioned drying treatment can be performed by heating the area by heating the entire area, or by heating the conveying roller (so-called using a heating roller) (heating roller drying method). It is preferable to use both. By using a heating roller to dry, the heating curl of the laminate can be effectively suppressed, and a polarizing film excellent in appearance can be manufactured. Specifically, by drying the laminate along the heating roller, the crystallization of the above thermoplastic resin substrate can be efficiently promoted to increase the degree of crystallization, even at a relatively low drying temperature, It can still increase the crystallinity of the thermoplastic resin substrate well. As a result, the rigidity of the thermoplastic resin base material is increased to be able to withstand the shrinkage of the PVA-based resin layer due to drying, so that curling is suppressed. In addition, by using a heating roller, the laminate can be dried while maintaining the flat state. Therefore, not only the generation of curl but also the generation of wrinkles can be suppressed. At this time, the laminate can be shrunk in the width direction by drying shrinkage treatment to improve the optical characteristics. It is because it can effectively improve the orientation of PVA and PVA/iodine complex.

C-8.其他處理 宜在水中延伸處理之後且在乾燥處理之前，施行洗淨處理。上述洗淨處理代表上可藉由使PVA系樹脂層浸漬於碘化鉀水溶液中來進行。 實施例C-8. Other processing It is advisable to perform washing treatment after extension treatment in water and before drying treatment. The above-mentioned cleaning treatment can be performed by immersing the PVA-based resin layer in an aqueous potassium iodide solution. Examples

以下，以實施例來具體說明本發明，惟本發明不受該等實施例限定。各特性之測定方法及評估方法如下所述。此外，只要無特別註記，實施例及比較例中之「份」及「%」即為重量基準。 (1)結晶化指數 針對空中延伸處理後之積層體，用傅立葉轉換紅外光譜光度計(Perkin Elmer公司製，製品名「SPECTRUM2000」)，並以偏光作為測定光，藉由ATR測定來評估PVA系樹脂層表面。具體而言，係於令測定偏光相對於延伸方向呈0°與90°之狀態下實施測定，並使用所得光譜之1141cm-1 及1140cm-1 的強度，依下述式算出結晶化指數。 結晶化指數＝((IC-0 +2×IC-90 )/3)/((IR-0 +2×IR-90 )/3) 惟， IC-0 ：將測定光(偏光)於與延伸方向平行之方向入射並進行測定時之1141cm-1 的強度 IC-90 ：將測定光(偏光)於與延伸方向垂直之方向入射並進行測定時之1141cm-1 的強度 IR-0 ：將測定光(偏光)於與延伸方向平行之方向入射並進行測定時之1140cm-1 的強度 IR-90 ：將測定光(偏光)於與延伸方向垂直之方向入射並進行測定時之1140cm-1 的強度 (2)定向函數 針對空中延伸處理後之積層體，用傅立葉轉換紅外光譜光度計(Perkin Elmer公司製，製品名「SPECTRUM2000」)，並以偏光作為測定光，藉由ATR測定來評估PVA系樹脂層表面。具體而言，係於令測定偏光相對於延伸方向呈0°與90°之狀態下實施測定，並使用2941cm-1 的強度，依下述式算出定向函數。 f＝(3>cos2 θ>-1)/2 ＝(1-D)/[c(2D+1)] 惟， c＝(3cos2 β-1)/2 β＝90deg⇒f＝-2×(1-D)/(2D+1) θ：分子鏈・延伸方向 β：分子鏈・偶極矩 D＝(I⊥)/(I//) (PVA分子越定向，D值越大) I⊥：將測定光(偏光)於與延伸方向垂直之方向入射並進行測定時之的強度 I//：將測定光(偏光)於與延伸方向平行之方向入射並進行測定時之的強度 (3)厚度參差 使用干涉膜厚計(大塚電子公司製，製品名「MCPD-3700」於與吸收軸正交之方向上從一端部至另一端部為止以間隔2mm測定實施例及比較例的偏光膜之厚度。 接著，算出從上述一端部至上述另一端部為止每50mm區域內的最大厚度與最小厚度之差，再算出各區域之上述差的平均值，並以上述平均值作為厚度參差。 (4)光學特性(單體透射率及偏光度) 針對實施例及比較例之偏光板(保護薄膜/偏光膜)，使用紫外線可見光分光光度計(日本分光公司製V-7100)進行測定，並將測得之單體透射率Ts、平行透射率Tp、正交透射率Tc分別作為偏光膜之Ts、Tp及Tc。該等Ts、Tp及Tc係以JIS Z8701之2度視野(C光源)進行測定並進行光視效能校正所得之Y值。另，保護薄膜之折射率為1.50，而偏光膜之與保護薄膜相反之側的表面之折射率為1.53。 從所得Tp及Tc利用下述式求得偏光度P。 偏光度P(%)={(Tp-Tc)/(Tp+Tc)}1/2 ×100 就所得單體透射率及偏光度之值依以下基準評估光學特性。 ○：偏光度在99.0%以上。(單體透射率＝44.5%) ×：偏光度低於99.0%。(單體透射率＝44.5%)Hereinafter, the present invention will be specifically described with examples, but the present invention is not limited by these examples. The measurement method and evaluation method of each characteristic are as follows. In addition, as long as there is no special note, "parts" and "%" in the examples and comparative examples are based on weight. (1) Crystallization index For the laminate after the air stretching process, use a Fourier transform infrared spectrophotometer (manufactured by Perkin Elmer, product name "SPECTRUM2000"), and use polarized light as the measurement light to evaluate the PVA system by ATR measurement The surface of the resin layer. Specifically, based on the embodiments make a polarizing phase is measured at a state of 0 ° and 90 °, and using the intensity of 1141cm -1 and 1140cm -1 of the extending direction of the resultant spectrum, crystallinity was calculated by the following formula index. Crystallization index = ((I C-0 +2×I C-90 )/3)/((I R-0 +2×I R-90 )/3) However, I C-0 : will determine the light ( polarization) 1141cm -1 when the intensity of the direction parallel to the extending direction of the incident and measured I C-90: 1141cm -1 when the intensity of the measuring light (polarized light) in the incident direction perpendicular to the extending direction and measured I R-0 : The intensity of 1140 cm -1 when measuring light (polarized light) is incident in a direction parallel to the extending direction and measuring I R-90 : Measuring light (polarized light) is incident and measured in a direction perpendicular to the extending direction The intensity of 1140 cm -1 at the time (2) Orientation function For the laminate after the air extension process, use a Fourier transform infrared spectrophotometer (manufactured by Perkin Elmer, product name "SPECTRUM2000"), and use polarized light as the measurement light by ATR measurement to evaluate the surface of the PVA-based resin layer. Specifically, the measurement is performed with the measurement polarized light at 0° and 90° with respect to the extending direction, and using the intensity of 2941 cm -1 , the orientation function is calculated according to the following formula. f=(3>cos 2 θ>-1)/2 =(1-D)/[c(2D+1)] However, c=(3cos 2 β-1)/2 β=90deg⇒f=-2 ×(1-D)/(2D+1) θ: molecular chain and extension direction β: molecular chain and dipole moment D = (I⊥)/(I//) (the more oriented the PVA molecule, the larger the D value) I⊥: Intensity when measuring light (polarized light) is incident in a direction perpendicular to the extension direction and measurement I//: Intensity when measuring light (polarized light) is incident in a direction parallel to the extension direction and measurement ( 3) Thickness variation using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3700") in the direction perpendicular to the absorption axis from one end to the other end at intervals of 2 mm to measure polarized light in Examples and Comparative Examples The thickness of the film. Next, the difference between the maximum thickness and the minimum thickness in each 50 mm area from the one end to the other end is calculated, and the average value of the difference in each area is calculated, and the average value is used as the thickness variation. (4) Optical characteristics (transmittance and polarizing degree of monomer) The polarizing plates (protective film/polarizing film) of Examples and Comparative Examples were measured using an ultraviolet visible light spectrophotometer (V-7100 manufactured by Japan Spectroscopy Co., Ltd.), and The measured single transmittance Ts, parallel transmittance Tp, and orthogonal transmittance Tc are respectively Ts, Tp, and Tc of the polarizing film. These Ts, Tp, and Tc are based on the 2-degree field of view of JIS Z8701 (C light source) The Y value obtained by the measurement and the correction of the optical performance is measured. In addition, the refractive index of the protective film is 1.50, and the refractive index of the surface of the polarizing film on the side opposite to the protective film is 1.53. From the obtained Tp and Tc, the following formula is used Obtain the polarization degree P. Polarization degree P(%)={(Tp-Tc)/(Tp+Tc)} 1/2 ×100 The optical transmittance and polarization value of the obtained monomer are evaluated according to the following criteria. ○ : Polarization degree is above 99.0%. (Single transmittance = 44.5%) ×: Polarization degree is less than 99.0%. (Single transmittance = 44.5%)

[實施例1] 1.製作偏光膜 熱塑性樹脂基材是使用長條狀且吸水率0.75%、Tg約75℃之非晶質異酞酸共聚聚對苯二甲酸乙二酯薄膜(厚度：100μm、寬度：1450mm)。並對樹脂基材之單面施行電暈處理(處理條件：55W・min/m2 )。 調製出以9：1之比包含聚乙烯醇(聚合度4200，皂化度99.2莫耳%)及乙醯乙醯基改質PVA(日本合成化學工業公司製，商品名「GOHSEFIMER Z410」)之PVA水溶液(塗佈液)。 於樹脂基材之電暈處理面塗佈上述PVA水溶液並在60℃下乾燥，藉此形成厚度8μm之PVA系樹脂層，而製作出積層體。 將所得積層體在延伸溫度設為120℃~130℃下，於周速相異的輥間往縱方向(長邊方向)進行自由端單軸延伸3.0倍(空中輔助延伸處理)。 接著，使積層體浸漬於液溫40℃的不溶解浴(相對於水100重量份摻混4重量份之硼酸而得的硼酸水溶液)中30秒(不溶解處理)。 接著，調整液溫30℃的染色浴(相對於水100重量份，以1：7之重量比摻混碘與碘化鉀而得之碘水溶液)之濃度以使最後所製得之偏光膜的單體透射率(Ts)成為44.5%並同時浸漬於其中60秒(染色處理)。 接著，使其浸漬於液溫40℃的交聯浴(相對於水100重量份，摻混3重量份的碘化鉀並摻混5重量份的硼酸而得之硼酸水溶液)中30秒(交聯處理)。 然後，一邊使積層體浸漬於液溫70℃的硼酸水溶液(硼酸濃度4.0重量%)中，一邊在周速相異的輥間往縱方向(長邊方向)進行單軸延伸以使總延伸倍率達5.5倍(水中延伸處理)。 之後，使積層體浸漬於液溫20℃的洗淨浴(相對於水100重量份，摻混4重量份的碘化鉀而得之水溶液)中(洗淨處理)。 之後，在烘箱中乾燥，藉此於樹脂基材上形成寬度1500mm且厚度3.5μm之偏光膜。 2.製作偏光板 於上述所製得之偏光膜表面(與樹脂基材相反之側的面)，透過紫外線硬化型接著劑貼合丙烯酸系薄膜(表面折射率1.50，40μm)作為保護薄膜。具體而言，是塗敷成硬化型接著劑之總厚度為1.0μm，並使用輥軋機進行貼合。其後，從保護薄膜側照射UV光線使接著劑硬化。接著，剝離樹脂基材，而製得具有保護薄膜/偏光膜之構成的偏光板。[Example 1] 1. A polarized film thermoplastic resin substrate was prepared by using a long-length amorphous isophthalic acid copolymerized polyethylene terephthalate film (thickness: 100 μm) with a water absorption of 0.75% and a Tg of about 75°C. , Width: 1450mm). Corona treatment is applied to one side of the resin substrate (treatment condition: 55W·min/m 2 ). A PVA containing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetylacetoyl modified PVA (manufactured by Japan Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z410") at a ratio of 9:1 was prepared Aqueous solution (coating liquid). The PVA aqueous solution was coated on the corona-treated surface of the resin base material and dried at 60°C, thereby forming a PVA-based resin layer with a thickness of 8 μm, to produce a laminate. The resulting laminate was subjected to a free-end uniaxial stretching 3.0 times in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds at a stretching temperature of 120°C to 130°C (air assisted stretching process). Next, the laminate was immersed in an insoluble bath (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (insoluble treatment). Next, the concentration of the dye bath (aqueous iodine solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30° C. is adjusted so that the monomer of the polarizing film finally prepared The transmittance (Ts) becomes 44.5% and is simultaneously immersed in it for 60 seconds (dyeing treatment). Next, it was immersed in a crosslinking bath (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C (crosslinking treatment ). Then, while immersing the laminate in a boric acid aqueous solution (boric acid concentration 4.0% by weight) at a liquid temperature of 70°C, uniaxial stretching was performed in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to increase the total stretching ratio Up to 5.5 times (extended treatment in water). Thereafter, the laminate was immersed in a washing bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 20° C. (washing treatment). After that, it was dried in an oven, thereby forming a polarizing film with a width of 1500 mm and a thickness of 3.5 μm on the resin substrate. 2. Fabricate a polarizing plate on the surface of the polarizing film (the surface opposite to the resin substrate) prepared above, and attach an acrylic film (surface refractive index 1.50, 40 μm) as a protective film through an ultraviolet curing adhesive. Specifically, the total thickness of the adhesive applied to the curing type is 1.0 μm, and the lamination is performed using a rolling machine. Thereafter, UV light is irradiated from the protective film side to harden the adhesive. Next, the resin substrate is peeled off, and a polarizing plate having a protective film/polarizing film structure is produced.

[實施例2] 除了於空中輔助延伸處理時將延伸倍率設為3.5倍外，依與實施例1相同方式而製作出偏光膜及偏光板。[Example 2] A polarizing film and a polarizing plate were produced in the same manner as in Example 1, except that the stretching magnification was set to 3.5 times during the air-assisted stretching process.

[比較例1] 於空中輔助延伸處理時將延伸倍率設為2.0倍，並將延伸溫度設為140℃，除此之外依與實施例1相同方式而製作出偏光膜及偏光板。[Comparative Example 1] In the air-assisted stretching process, the stretching magnification was set to 2.0 times and the stretching temperature was set to 140° C. Other than that, a polarizing film and a polarizing plate were produced in the same manner as in Example 1.

[比較例2] 除了於空中輔助延伸處理時將延伸倍率設為2.4倍外，依與實施例1相同方式而製作出偏光膜及偏光板。[Comparative Example 2] A polarizing film and a polarizing plate were produced in the same manner as in Example 1, except that the stretching magnification was set to 2.4 times during the air-assisted stretching process.

[比較例3] 於空中輔助延伸處理時將延伸倍率設為4.0倍，並將延伸溫度設為140℃，除此之外依與實施例1相同方式而嘗試製作出偏光膜，但積層體於水中延伸處理時斷裂，而無法製作出偏光膜及偏光板。[Comparative Example 3] In the air-assisted stretching process, the stretching magnification was set to 4.0 times, and the stretching temperature was set to 140°C. Except that, in the same manner as in Example 1, an attempt was made to produce a polarizing film, but the laminate was broken during the stretching process in water. , And unable to produce polarizing film and polarizing plate.

[比較例4] 於空中輔助延伸處理時將延伸倍率設為4.5倍，並且未施行水中延伸處理，除此之外依與實施例1相同方式而製作出偏光膜及偏光板。[Comparative Example 4] In the air-assisted stretching process, the stretching magnification was set to 4.5 times, and the underwater stretching process was not performed, except that a polarizing film and a polarizing plate were produced in the same manner as in Example 1.

>評估> 針對實施例及比較例，依上述(1)及(2)算出空中延伸處理後之PVA系樹脂層的結晶化指數及定向函數，依上述(3)算出偏光膜之厚度參差，且依上述(4)算出偏光板之光學特性，進行評估。並且確認在將實施例及比較例之偏光板應用於影像顯示裝置時有無條痕不均。將結果列於表1。>Evaluation> For the examples and comparative examples, the crystallization index and orientation function of the PVA-based resin layer after the air stretching process were calculated according to (1) and (2) above, and the thickness variation of the polarizing film was calculated according to (3) above, and according to ( 4) Calculate the optical characteristics of the polarizer and evaluate it. Furthermore, it was confirmed whether there were uneven streaks when the polarizing plates of Examples and Comparative Examples were applied to an image display device. The results are listed in Table 1.

[表1]

Figure 02_image001
[Table 1]
Figure 02_image001

由表1可知，比較例1及4之偏光板的光學特性低，且比較例1及2之偏光板有視辨出條痕不均。在比較例3之製造條件下，則積層體於水中延伸處理時會斷裂，而甚至無法製作出偏光膜。相對地，實施例1及2之偏光板則具有優異光學特性，而未確認到有條痕不均。It can be seen from Table 1 that the polarizing plates of Comparative Examples 1 and 4 have low optical characteristics, and the polarizing plates of Comparative Examples 1 and 2 have visible unevenness in streaks. Under the manufacturing conditions of Comparative Example 3, the laminate will break when stretched in water, and even a polarizing film cannot be produced. In contrast, the polarizing plates of Examples 1 and 2 had excellent optical characteristics, and no unevenness of streak was confirmed.

產業上之可利用性 本發明之偏光膜可適用於影像顯示裝置。Industrial availability The polarizing film of the present invention can be applied to image display devices.

10‧‧‧偏光膜 20‧‧‧第1保護層 30‧‧‧第2保護層 100‧‧‧偏光板10‧‧‧ Polarizing film 20‧‧‧1st protective layer 30‧‧‧Second protective layer 100‧‧‧ Polarizer

圖1係本發明之一實施形態之偏光板的概略截面圖。FIG. 1 is a schematic cross-sectional view of a polarizing plate according to an embodiment of the present invention.

10‧‧‧偏光膜 10‧‧‧ Polarizing film

20‧‧‧第1保護層 20‧‧‧The first protective layer

30‧‧‧第2保護層 30‧‧‧Second protective layer

100‧‧‧偏光板 100‧‧‧ Polarizer

Claims (5)

一種偏光膜，其厚度為8μm以下，且 沿與吸收軸正交之方向從一端部至另一端部為止每50mm之區域的最大厚度與最小厚度之差的平均值為70nm以下。A polarizing film with a thickness of 8 μm or less, and The average value of the difference between the maximum thickness and the minimum thickness per area of 50 mm from one end to the other end in the direction orthogonal to the absorption axis is 70 nm or less. 如請求項1之偏光膜，其單體透射率為44.5%以上，且偏光度為99.0%以上。If the polarizing film of claim 1, its single transmittance is 44.5% or more, and its polarization degree is 99.0% or more. 一種偏光板，具有：如請求項1或2之偏光膜與配置於該偏光膜之至少一側的保護層。A polarizing plate, comprising: the polarizing film according to claim 1 or 2, and a protective layer disposed on at least one side of the polarizing film. 一種偏光膜之製造方法，包含以下步驟： 於熱塑性樹脂基材之單側形成含聚乙烯醇系樹脂之聚乙烯醇系樹脂層，而製成積層體；及 對前述積層體依序施行空中延伸處理與染色處理； 前述空中延伸處理後之前述聚乙烯醇系樹脂層利用衰減全反射分光測定算出之結晶化指數為1.55以上且1.7以下，且定向函數為0.22以上且0.31以下。A method for manufacturing polarizing film includes the following steps: Forming a polyvinyl alcohol-based resin layer containing a polyvinyl alcohol-based resin on one side of the thermoplastic resin substrate to form a laminate; and Perform aerial extension treatment and dyeing treatment on the aforementioned laminate in sequence; The polyvinyl alcohol-based resin layer after the air stretching process has a crystallization index calculated by attenuation total reflection spectrometry of 1.55 or more and 1.7 or less, and the orientation function is 0.22 or more and 0.31 or less. 如請求項4之偏光膜之製造方法，其於前述空中延伸處理之後更包含對前述積層體施行水中延伸處理； 前述空中延伸處理之延伸倍率為3.0倍以上，且前述水中延伸處理之延伸倍率為1.8倍以下。The method for manufacturing a polarizing film according to claim 4, which further includes performing an underwater stretching process on the laminate after the aerial stretching process; The stretching magnification of the aerial stretching process is 3.0 times or more, and the stretching magnification of the underwater stretching process is 1.8 times or less.
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