TWI801599B - Polarizing film and method for manufacturing polarizing film - Google Patents

Polarizing film and method for manufacturing polarizing film Download PDF

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TWI801599B
TWI801599B TW108119950A TW108119950A TWI801599B TW I801599 B TWI801599 B TW I801599B TW 108119950 A TW108119950 A TW 108119950A TW 108119950 A TW108119950 A TW 108119950A TW I801599 B TWI801599 B TW I801599B
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stretching
treatment
polarizing film
pva
based resin
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TW202007518A (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

本發明提供一種可抑制條痕不均產生的偏光膜。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。The present invention provides a polarizing film capable of suppressing uneven streaks. 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 50 mm area from one end to the other end in the 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 for 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 manufacturing method of 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 which is a typical image display device, polarizing films are arranged on both sides of the liquid crystal cell according to the image forming method. Moreover, with the popularization of thin displays, displays equipped with organic EL panels (OLED) and displays using display panels using inorganic light-emitting materials such as quantum dots (QLED) have also been proposed, and polarizing films can also be applied to these images. display device. A method for producing a polarizing film, for example, has been proposed in which a laminate having a resin substrate and a polyvinyl alcohol (PVA) resin layer is extended, and then dyed to obtain a polarizing film on the resin substrate (for example, Patent Document 1). A thinner polarizing film can be obtained by this method, so it can contribute to the thinning of image display devices in recent years and has attracted attention. However, when the above-mentioned conventional thin polarizing film is applied to an image display device, streaks and unevenness 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 art literature patent documents 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 The problem to be solved by the invention The present invention is made to solve the above-mentioned conventional problems, and its main purpose is to provide a polarizing film capable of suppressing the occurrence of uneven streaks and a method for 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。method 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 50 mm area from one end to the other end in the direction perpendicular 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 polarizer is provided. The polarizing plate has: the above-mentioned polarizing film and a protective layer disposed on at least one side of the above-mentioned 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 comprises 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 aerial stretching on the above-mentioned laminate. Treatment and dyeing treatment: The above-mentioned polyvinyl alcohol-based resin layer after the above-mentioned aerial stretching treatment has a crystallization index calculated by attenuated total reflection spectroscopy of 1.55 to 1.7, and an orientation function of 0.22 to 0.31. In one embodiment, after the above-mentioned aerial stretching treatment, further includes performing underwater stretching treatment on the above-mentioned laminate; the stretching ratio of the above-mentioned aerial stretching treatment is 3.0 times or more, and the stretching ratio of the above-mentioned underwater stretching treatment 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。form for carrying out the invention Embodiments of the present invention will be described below, but the present invention is not limited to 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 area from one end to the other end along the direction perpendicular to the absorption axis (sometimes below Called thickness variation) is 70nm or less. Thickness variation, for example, can measure the thickness of the polarizing film at intervals of 2mm from the above-mentioned one end to the other end, calculate the difference between the maximum thickness and the minimum thickness in each 50mm area, and then calculate the average value of the above differences in each area to obtain have to. The thickness of the polarizing film can typically be measured using an optical interference film thickness gauge. Conventional thin polarizing films have thickness variations along the direction perpendicular to the absorption axis due to their manufacturing methods. As a result, streaks along the absorption axis may be uneven when applied to image display devices. Regardless of whether the thickness of the polarizing film of this embodiment is very thin or not, the variation in thickness is small. When the polarizing film is applied to an image display device, it can suppress uneven streaks.

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 less than 50nm, preferably less than 40nm, and most preferably less than 30nm. The thickness variation should be small, but actually the lower limit is, for example, 5 nm.

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 monomer 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 above 45.0%. The polarization degree of the polarizing film is more preferably 99.5% or more, and more preferably 99.9% or more. The above-mentioned single transmittance is representatively the Y value obtained by measuring with an ultraviolet-visible spectrophotometer and correcting for optical performance. The above-mentioned degree of polarization is representatively obtained by the following formula based on the parallel transmittance Tp and the cross transmittance Tc obtained by measuring with an ultraviolet-visible spectrophotometer and performing light performance correction. Degree of 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 a thermoplastic resin substrate to form a laminate; And, the aerial stretching treatment and the dyeing treatment are sequentially performed on the above-mentioned laminated body. The crystallization index of the PVA-based resin layer after the above-mentioned in-air stretching process measured by attenuated total reflection spectroscopy (ATR) is not less than 1.55 and not more than 1.7, and the orientation function is not less than 0.22 and not more than 0.31. By controlling the crystallization index and orientation function of the PVA-based resin layer after air-stretching treatment within the above-mentioned ranges, a polarizing film with thin thickness, small thickness variation and high optical properties can be produced.

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 air-stretching is obtained by ATR measurement with a Fourier transform infrared spectrophotometer (FT-IR) and polarized light as the measuring light. Specifically, the measurement was carried out with the measurement polarized light at 0° and 90° with respect to the extending direction, and the intensity at 1141 cm -1 and 1140 cm -1 of the obtained spectrum was used for calculation according to the following formula. In addition, the strength of 1141 cm -1 has a correlation with the amount of crystallization portion 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 : the measured light ( Intensity I of 1141 cm -1 when measuring light (polarized light) incident in a direction parallel to the extending direction and measured C-90 : Intensity I of 1141 cm -1 when measuring light (polarized light) is incident in a direction perpendicular to the extending direction R-0 : Intensity I of 1140 cm -1 when measurement light (polarized light) is incident in a direction parallel to the stretching direction and measured I R-90 : Measurement light (polarized light) is incident in a direction perpendicular to the stretching direction and measured Intensity at 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 in-air stretching process is obtained by ATR measurement using FT-IR, for example, using polarized light as the measurement light. Specifically, the measurement was carried out in a state where the measurement polarization was 0° and 90° with respect to the extending direction, and the intensity at 2941 cm -1 of the obtained spectrum was used to calculate according to the following formula. Here, the intensity I is the value of 2941cm -1 /3330cm -1 with 3330cm -1 as the reference peak. In addition, when f=1, it is completely oriented, and when f=0, it is random. Also, we think that the peak at 2941 cm -1 is due to the absorption of the 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 measured I//: Intensity when measuring light (polarized light) is incident in a direction parallel to the extending direction and measured

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 has 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 item A above. One of the first protective layer 20 and the second protective layer 30 may also be omitted. In addition, one of the first protective layer and the second protective layer may be a resin base material used to manufacture the above-mentioned 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 appropriate film that can be used as a protective layer of a polarizing film. Specific examples of the material of the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, polyamide-based resins, etc. Imine-based, polyether-based, polystyrene-based, polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic-based and acetate-based transparent resins, etc. Further, thermosetting resins such as (meth)acrylic, urethane, (meth)acrylate urethane, epoxy, and silicone, or ultraviolet curable resins are also mentioned. Other examples include glassy polymers such as siloxane polymers. Furthermore, a 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 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, such as A resin composition having an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer may be mentioned. The polymer film can be, for example, an extruded product of the above-mentioned 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) arranged on the side opposite to the display panel is typically not more than 300 μm, preferably not more than 100 μm, more preferably 5 μm to 80 μm, and more preferably It is preferably 10 μm to 60 μm. 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 (inner protective layer) disposed on the display panel side is preferably 5 μm to 200 μm, more preferably 10 μm to 100 μm, and more preferably 10 μm to 60 μm. In one embodiment, the inner protective layer is a retardation layer having an arbitrary and appropriate retardation value. As the retardation layer, a retardation film having 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 retardation is usually controlled in the range of 40~200nm, and the retardation in the thickness direction is usually controlled in the range of 80~300nm. Examples of retardation films include birefringent films obtained by uniaxially or biaxially stretching polymer materials, alignment films of liquid crystal polymers, and alignment layers of liquid crystal polymers supported by films. The thickness of the retardation film is not particularly limited, and is generally about 20-150 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 method for producing a polarizing film according to an embodiment of the present invention is as described above, including 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, The above-mentioned laminated body is sequentially subjected to aerial stretching treatment and dyeing treatment. The above-mentioned polyvinyl alcohol-based resin layer after the above-mentioned in-air stretching treatment has a crystallization index calculated by attenuated total reflection spectroscopy of 1.55 to 1.7, and an orientation function of 0.22 to 0.31. Preferably, after the aerial stretching treatment, the laminate is subjected to underwater stretching treatment; the stretching ratio of the aerial stretching treatment is 3.0 times or more, and the stretching ratio of the underwater stretching treatment is 1.8 times or less. According to the above, compared with the previous manufacturing method, setting the stretching ratio of the aerial stretching treatment to be higher and setting the stretching ratio of the underwater stretching treatment to be lower can promote the crystallization of the PVA resin layer after the aerial stretching treatment and at the same time suppress excessive crystallization of the thermoplastic resin substrate. In this way, a polarizing film with small thickness variation and excellent optical properties 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. Fabrication of laminated body Arbitrary and appropriate methods can be adopted for the method of producing the laminate of the thermoplastic resin base material and the PVA-based resin layer. Preferably, the coating solution containing PVA-based resin is coated on the surface of the elongated thermoplastic resin substrate and dried, 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。Any appropriate method can be adopted for the coating method of the coating liquid. Examples include roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, knife coating (comma coating, etc.) and the like. The coating and drying temperature of the above-mentioned coating solution 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, 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 can be subjected to surface treatment (such as corona treatment, etc.), and an easy-adhesive layer can also be formed on the thermoplastic resin substrate. By performing the above treatment, the adhesion between the thermoplastic resin substrate 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 larger than 300 μm, it may take a long time for the thermoplastic resin base material to absorb water during elongation treatment in water as described later, and there is a possibility that excessive load will be imposed on the elongation.

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 above 0.2%, more preferably above 0.3%. The thermoplastic resin substrate absorbs water, and the water acts as a plasticizer for plasticization. As a result, elongation stress can be greatly reduced and high-magnification elongation can be achieved. On the other hand, the water absorption of the thermoplastic resin substrate is preferably 3.0% or less, 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 remarkably lowered during production, which would cause poor appearance of the obtained polarizing film, and the like. It can also prevent the substrate from breaking when it is stretched in water, or the PVA-based resin layer from peeling off from the thermoplastic resin substrate. In addition, the water absorption rate of the thermoplastic resin substrate can be adjusted, for example, by introducing a modifying group into the constituent material. The water absorption is a value obtained 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 below 120°C. By using such a thermoplastic resin base material, the crystallization of the PVA-based resin layer can be suppressed, and the extensibility of the laminate can be sufficiently ensured. In addition, in consideration of plasticizing the thermoplastic resin substrate with water and good underwater stretching, it is more preferably below 100°C, more preferably below 90°C. 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 (such as unevenness, drooping or wrinkling, etc.) when coating and drying the coating liquid containing the above-mentioned PVA-based resin, Thereby, a laminated body was produced satisfactorily. In addition, the stretching of the PVA-based resin layer can be favorably performed at an appropriate temperature (for example, about 60° C.). In addition, the glass transition temperature of the thermoplastic resin substrate can be adjusted by heating, for example, a crystallization material capable of introducing a modifying group into the constituent material. The glass transition temperature (Tg) is a value calculated based on 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。Arbitrary and appropriate thermoplastic resins can be used as the constituent material of the thermoplastic resin base material. Examples of thermoplastic resins include ester-based resins such as polyethylene terephthalate-based resins, cycloolefin-based resins such as norcamphene-based resins, olefin-based resins such as polypropylene, polyamide-based resins, polycarbonate-based resins, and Other copolymer resins, etc. Among these, norcamphene-based resins and amorphous polyethylene terephthalate-based resins are preferable.

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, it is particularly preferable to use an amorphous (difficult to crystallize) polyethylene terephthalate resin. Specific examples of amorphous polyethylene terephthalate-based resins include copolymers that further contain isophthalic acid and/or cyclohexanedicarboxylic acid as dicarboxylic acids, or copolymers that further contain Copolymers of cyclohexanedimethanol 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 an isophthalic acid unit. This is because the thermoplastic resin base material has extremely excellent extensibility and can suppress crystallization at the time of elongation. We speculate that this is due to the large flexure imparted to the main chain by the introduction of isophthalic acid units. The polyethylene terephthalate resin has a terephthalic acid unit and an ethylene glycol unit. The content ratio of the isophthalic acid unit is preferably 0.1 mol% or more, more preferably 1.0 mol% or more, based on the total of all repeating units. This is because a thermoplastic resin substrate with excellent extensibility can be obtained. On the other hand, the content ratio of the isophthalic acid unit is preferably 20 mol% or less, more preferably 10 mol% or less, based on the total of all repeating units. By setting the above-mentioned 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 substrate may also have been pre-stretched (before forming the PVA-based resin layer). In one embodiment, it has been extended in the transverse direction of the elongated thermoplastic resin substrate. The lateral direction is preferably a direction perpendicular to the extending direction of the laminate described later. In addition, the term "orthogonal" in this specification also includes the case of being substantially orthogonal. Here, "substantially orthogonal" includes the case of 90°±5.0°, preferably 90°±3.0°, more preferably 90°±1.0°. The stretching temperature of the thermoplastic resin substrate is preferably Tg-10°C~Tg+50°C relative to the glass transition temperature (Tg). The elongation ratio of the thermoplastic resin substrate should be 1.5 times to 3.0 times. An arbitrary and appropriate method can be adopted for the stretching method of the thermoplastic resin base material. Specifically, it can be extended from a fixed end, or can be extended from a free end. The extension method can be dry or wet. The stretching of the thermoplastic resin substrate can be carried out in one stage or in multiple stages. When it is carried out in multiple stages, the above-mentioned elongation ratio is the product of the elongation ratios of 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 solution The above-mentioned coating solution refers to a solution obtained by dissolving the above-mentioned PVA-based resin in a solvent. Examples of the solvent include water, dimethylsulfide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, ethylene glycol, and the like. Amines such as diamine and diethylenetriamine. These may be used alone or in combination of two or more. Among them, water is the best. The concentration of the PVA-based 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 above-mentioned resin concentration, a uniform coating film can be formed in close contact with the thermoplastic resin substrate.

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 may also be blended 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 obtained 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。Arbitrary and appropriate resins can be used for the above-mentioned PVA-based resin. Examples thereof include polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. Ethylene-vinyl alcohol copolymer can be obtained by saponifying ethylene-vinyl acetate copolymer. The saponification degree of the PVA-based resin is usually 85 mol %-100 mol %, preferably 95.0 mol %-99.95 mol %, more preferably 99.0 mol %-99.93 mol %. The degree of saponification is obtained in accordance with JIS K 6726-1994. A polarizing film excellent in durability can be obtained by using a PVA-based resin having such a degree of saponification. When the degree of saponification is too high, gelation may occur.

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 degree of polymerization is usually 1000-10000, preferably 1200-4500, more preferably 1500-4300. In addition, the average degree of polymerization can be obtained according to 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 Extended Processing The elongation ratio of aerial elongation treatment 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, as described above, by setting the stretching ratio of the in-air stretching process higher than the conventional manufacturing method, the stretching ratio for realizing desired optical characteristics in the underwater stretching process described later can be set lower. Low. Thereby, excessive crystallization of the thermoplastic resin base material caused by the underwater stretching treatment 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 stretching method of aerial auxiliary stretching can be fixed end stretching (such as stretching method using a tenter stretching machine), or free end stretching (such as the method of uniaxial stretching the laminated body through rollers with different peripheral speeds) , but in order to obtain high optical properties, free end extensions can be actively used. In one embodiment, the in-air stretching process includes a heating roll stretching step of conveying the elongated laminate in the direction of its long side and simultaneously stretching using the difference in peripheral speed between the heating rolls. In-air stretching typically includes a zone stretching step and a heating roll stretching step. In addition, the order of the zone stretching step and the heating roller stretching step is not limited, and the zone stretching step or the heating roller stretching step may be performed first. The region extension step can also be omitted. In one embodiment, the region stretching step and the heating roll stretching step are performed sequentially. In another embodiment, the end of the film is held in a tenter stretching machine, and the distance between the tenters is increased in the traveling direction to stretch (the increase in the distance between the tenters is the stretching ratio). At this time, the distance of the tenter in the width direction (vertical direction with respect to the traveling direction) is set so as to be arbitrarily close. Preferably, it can be set so that the extension ratio relative to the direction of travel can be approached by extending the free end. When the free end is extended, it is calculated as the shrinkage rate 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。Aerial assisted extension can be performed in one phase or in multiple phases. When it is carried out in multiple stages, the extension ratio is the product of the extension ratios of each stage. The direction of extension in aerial auxiliary extension should be approximately the same as that of 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 elongation magnification when combining aerial auxiliary elongation and underwater elongation is preferably 5.0 times or more, more preferably 5.5 times or more, and more preferably 6.0 times or more relative to the original length of the laminate. The "maximum elongation ratio" in this specification means the elongation ratio immediately before the laminate is broken, and is a value 0.2 lower than the value obtained by separately confirming the elongation ratio of the laminate fracture.

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 stretching temperature of the air-assisted stretching can be set to any and appropriate value according to the forming material of the thermoplastic resin substrate, the stretching method, and the like. The stretching temperature is preferably above the glass transition temperature (Tg) of the thermoplastic resin substrate, more preferably above the glass transition temperature (Tg)+10°C of the thermoplastic resin substrate, especially above Tg+15°C. On the other hand, the upper limit of the stretching temperature is preferably 170°C. Stretching at such a temperature suppresses rapid progress of crystallization of the PVA-based resin, thereby suppressing disadvantages caused by the crystallization (for example, interruption of orientation of the PVA-based resin layer due to stretching).

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 Insolubilization treatment is performed after the air-assisted stretching treatment and before the underwater stretching treatment or dyeing treatment as necessary. The above-mentioned insolubilization treatment is typically carried out by immersing the PVA-based resin layer in a boric acid aqueous solution. By performing insolubilization treatment, water resistance can be imparted to the PVA-based resin layer, and the orientation of PVA can be prevented from being lowered when immersed in water. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight relative to 100 parts by weight of water. The liquid temperature of the insoluble bath (boric acid aqueous solution) should be 20°C~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 is representatively carried out by dyeing the PVA-based resin layer with iodine. Specifically, it is performed by adsorbing iodine on the PVA-based resin layer. Examples of the adsorption method include: a method of immersing the PVA resin layer (laminate) in a dyeing solution containing iodine, a method of applying the dyeing solution to the PVA resin layer, and spraying the dyeing solution onto the PVA. The method on the resin layer, etc. A method of immersing the laminate in a dyeing solution (dyeing bath) is preferably employed. This is because iodine can be well adsorbed.

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-mentioned dyeing solution is preferably iodine aqueous 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 increase the solubility of iodine in water, it is advisable 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, titanium iodide and the like. Among these, potassium iodide is preferable. The blending amount of iodide is preferably 0.1 to 10 parts by weight, more preferably 0.3 to 5 parts by weight, relative to 100 parts by weight of water. In order to inhibit the dissolution of PVA-based resin, the liquid temperature of the dyeing solution during dyeing should be 20°C~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。Dyeing conditions (concentration, liquid temperature, and immersion time) can be set so that the degree of polarization or monomer transmittance of the finally obtained polarizing film falls within a predetermined range. In one embodiment, the immersion time is set so that the single-body transmittance of the obtained polarizing film becomes 44.5%-45.0%. In another embodiment, the immersion time is set so that the polarization degree of the obtained polarizing film may become 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 dyeing treatment is carried out after immersing the laminate in a treatment bath containing boric acid (typically insolubilization treatment), 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 dyeing bath. As time changes, the dyeing properties may become unstable as a result. In order to suppress destabilization of dyeability as described above, the upper limit of the concentration of boric acid in the dyeing bath is adjusted to preferably 4 parts by weight, more preferably 2 parts by weight, relative to 100 parts by weight of water. On the other hand, the lower limit of the concentration of boric acid in 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 treatment is performed using a dyeing bath premixed with boric acid. Thereby, the rate at which the boric acid concentration changes when the boric acid in the treatment bath mentioned above is mixed into the dyeing bath can be reduced. The amount of boric acid mixed in the dyeing bath in advance (that is, the content of boric acid not derived from the above-mentioned 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 After the dyeing treatment and before the stretching treatment in water, a crosslinking treatment is performed as necessary. Typically, the above-mentioned crosslinking treatment can be performed by immersing the PVA-based resin layer in a boric acid aqueous solution. By performing cross-linking treatment, water resistance can be imparted to the PVA-based resin layer, and the orientation of PVA can be prevented from being lowered when immersed in high-temperature water during subsequent underwater stretching. The concentration of the boric acid aqueous solution is preferably 1 to 5 parts by weight relative to 100 parts by weight of water. In addition, when carrying out the crosslinking treatment after the above-mentioned dyeing treatment, it is preferable to further blend iodide. By mixing iodide, the elution of iodine adsorbed to the PVA-based resin layer can be suppressed. The blending amount of iodide is preferably 1 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) should be 20°C~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 treatment in water The elongation ratio of the underwater elongation treatment is preferably less than 1.8 times, preferably less than 1.5 times. Thereby, excessive crystallization of the thermoplastic resin base material caused by the underwater stretching treatment can be suppressed. In addition, it is possible to realize a high total stretching ratio in combination with auxiliary stretching in the air, and to manufacture a polarizing film with extremely excellent optical characteristics.

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 a stretching bath. By stretching in water, it can be stretched at a temperature lower than the glass transition temperature (typically about 80°C) of the above-mentioned thermoplastic resin substrate or PVA-based resin layer, and can suppress the crystallization of the PVA-based resin layer at the same time Perform high-magnification extensions. As a result, a polarizing film with excellent optical properties 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。An arbitrary and appropriate method can be used for the stretching method of the laminate. Specifically, it may be fixed-end stretching or free-end stretching (for example, a method of uniaxially stretching a laminate through rolls having different circumferential speeds). Preferably a free end extension is selected. The extension of the laminate may be performed in one step or in multiple steps. When it is carried out in multiple stages, the elongation ratio (maximum elongation ratio) of the laminate described later is the product of the elongation ratios of 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 underwater stretching is preferably carried out by immersing the laminate in an aqueous solution of boric acid (boric acid underwater stretching). By using an aqueous solution of boric acid as a stretching bath, the PVA-based resin layer can be given rigidity to withstand tension during stretching and water resistance that is insoluble in water. Specifically, boric acid generates tetrahydroxyboric acid anion in aqueous solution, which can cross-link with PVA-based resin through hydrogen bonding. As a result, rigidity and water resistance can be imparted to the PVA-based resin layer, and good stretching can be performed, thereby producing a polarizing film with excellent optical properties.

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 above boric acid aqueous solution is preferably obtained by dissolving boric acid and/or borate in water as a solvent. On the other hand, the boric acid concentration is preferably 1 to 10 parts by weight, more preferably 2.5 to 6 parts by weight, and particularly preferably 3 to 5 parts by weight relative to 100 parts by weight of water. 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 produced. In addition, an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde, etc. in a solvent other than boric acid or borate 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 convenient to mix iodide in the above-mentioned extension bath (boric acid aqueous solution). By mixing iodide, the elution of iodine adsorbed to the PVA-based resin layer can be suppressed. Specific examples of iodide are as described above. The concentration of iodide is preferably 0.05 to 15 parts by weight, more preferably 0.5 to 8 parts by weight, relative to 100 parts by weight of water.

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 stretching temperature (liquid temperature of the stretching bath) is preferably 40°C~85°C, more preferably 60°C~75°C. As long as it is the above-mentioned temperature, the dissolution of the PVA-based resin layer can be suppressed, and high-magnification stretching can be achieved. 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 base material is preferably 60° C. or higher. At this time, if the stretching temperature is lower than 40° C., good stretching may not be possible even considering plasticizing the thermoplastic resin base material with water. 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 not be possible to obtain excellent optical properties. The immersion time of the laminate in the stretching 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 treatment The above-mentioned drying treatment may be carried out by heating the entire region by heating the region, or by heating the conveying roller (so-called use of a heating roller) (heating roller drying method). It is preferable to use both. By drying with a heating roll, heating curl of the laminate can be effectively suppressed, and a polarizing film having an excellent appearance can be produced. Specifically, by drying the laminated body along the heating roll, the crystallization of the above-mentioned thermoplastic resin substrate can be effectively 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 substrate is increased so that it can withstand shrinkage of the PVA-based resin layer due to drying, thereby suppressing curling. Moreover, since the layered body can be dried while maintaining the flat state by using the heating roller, not only the occurrence of curl but also the occurrence of wrinkling can be suppressed. At this time, the laminated body can be shrunk in the width direction through drying shrinkage treatment, so as to improve the optical properties. It is because it can effectively improve the orientation of PVA and PVA/iodine complexes.

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 preferable to carry out the washing treatment after the stretching treatment in water and before the drying treatment. Typically, the cleaning treatment described above can be performed by immersing the PVA-based resin layer in an aqueous potassium iodide solution. Example

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, "parts" and "%" in Examples and Comparative Examples are based on weight unless otherwise noted. (1) Crystallization index For the laminate after aerial extension treatment, use a Fourier transform infrared spectrophotometer (manufactured by Perkin Elmer, product name "SPECTRUM2000"), and use polarized light as the measurement light, and evaluate the PVA system by ATR measurement. resin layer surface. Specifically, the measurement was carried out with the measurement polarized light at 0° and 90° with respect to the extending direction, and the crystallization index was calculated according to the following formula using the intensities of 1141 cm -1 and 1140 cm -1 of the obtained spectrum. Crystallization index = ((I C-0 +2×I C-90 )/3)/((I R-0 +2×I R-90 )/3) However, I C-0 : the measured light ( Intensity I of 1141 cm -1 when measuring light (polarized light) incident in a direction parallel to the extending direction and measured C-90 : Intensity I of 1141 cm -1 when measuring light (polarized light) is incident in a direction perpendicular to the extending direction R-0 : Intensity I of 1140 cm -1 when measurement light (polarized light) is incident in a direction parallel to the stretching direction and measured I R-90 : Measurement light (polarized light) is incident in a direction perpendicular to the stretching direction and measured The intensity at 1140 cm -1 (2) Orientation function For the laminated body 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 was used to evaluate the surface of the PVA-based resin layer. Specifically, the measurement was carried out in a state where the measurement polarization was 0° and 90° with respect to the extending direction, and the orientation function was calculated according to the following formula using the intensity at 2941 cm −1 . 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 measured I//: Intensity when measuring light (polarized light) is incident in a direction parallel to the extending direction and measured ( 3) Thickness variation Using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3700"), the polarized light of the examples and comparative examples was measured from one end to the other end in the direction perpendicular to the absorption axis at intervals of 2 mm. Thickness of the film: Next, calculate the difference between the maximum thickness and the minimum thickness in every 50mm area from the above-mentioned one end to the above-mentioned other end, and then calculate the average value of the above-mentioned differences in each area, and use the above-mentioned average value as the thickness variation. (4) Optical properties (single transmittance and degree of polarization) The polarizing plates (protective film/polarizing film) of Examples and Comparative Examples were measured using an ultraviolet-visible spectrophotometer (V-7100 manufactured by JASCO Corporation), and The measured single transmittance Ts, parallel transmittance Tp, and orthogonal transmittance Tc are respectively used as 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) Carry out the Y value that carries out measurement and carry out optical performance correction gained.In addition, the refractive index of protective film is 1.50, and the refractive index of the polarizing film and the surface of the opposite side of protective film is 1.53. Utilize following formula from gained Tp and Tc Obtain the degree of polarization P. Degree of polarization P(%)={(Tp-Tc)/(Tp+Tc)} 1/2 ×100 Based on the values of the obtained single transmittance and degree of polarization, evaluate the optical properties according to the following criteria. ○ : The polarization degree is above 99.0%. (Single transmittance = 44.5%) ×: The polarization degree is lower 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. Making a polarizing film The thermoplastic resin substrate is an amorphous isophthalic acid copolymerized polyethylene terephthalate film (thickness: 100 μm , Width: 1450mm). And perform corona treatment on one side of the resin substrate (treatment condition: 55W·min/m 2 ). Prepared PVA containing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mole%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z410") in a ratio of 9:1 Aqueous solution (coating solution). The above-mentioned PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60° C. to form a PVA-based resin layer with a thickness of 8 μm, thereby producing a laminate. The obtained laminate was uniaxially stretched 3.0 times at the free end in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds at a stretching temperature of 120°C to 130°C (in-air assisted stretching treatment). Next, the laminate was immersed in an insoluble bath (an aqueous solution of boric acid 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, adjust the concentration of the dyeing bath (with respect to 100 parts by weight of water, an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7) with a liquid temperature of 30° C. so that the monomer of the polarizing film finally obtained The transmittance (Ts) becomes 44.5% while being immersed therein 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. for 30 seconds (crosslinking treatment). ). Then, while the laminate was immersed in a boric acid aqueous solution (boric acid concentration: 4.0% by weight) at a liquid temperature of 70°C, it was uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different circumferential speeds so that the total stretching ratio Up to 5.5 times (extended treatment in water). Thereafter, the laminate was immersed in a cleaning bath (an 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). Thereafter, by drying in an oven, a polarizing film having a width of 1500 mm and a thickness of 3.5 μm was formed on the resin substrate. 2. Make a polarizing plate. On the surface of the polarizing film prepared above (the side opposite to the resin substrate), stick an acrylic film (surface refractive index 1.50, 40 μm) through a UV-curable adhesive as a protective film. Specifically, it was applied so that the total thickness of the hardening adhesive was 1.0 μm, and bonded using a rolling mill. Thereafter, UV rays are irradiated from the protective film side to cure the adhesive. Next, the resin base material was peeled off, and the polarizing plate which has the structure of a protective film/polarizing film was manufactured.

[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 ratio was set to 3.5 times during the auxiliary stretching process in the air.

[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] A polarizing film and a polarizing plate were produced in the same manner as in Example 1 except that the stretching ratio was set to 2.0 times and the stretching temperature was set to 140° C. during the in-air assisted stretching process.

[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 ratio was set to 2.4 times during the auxiliary stretching process in the air.

[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 ratio was set to 4.0 times, and the stretching temperature was set to 140°C. In addition, it was tried to produce a polarizing film in the same manner as in Example 1, but the laminate was broken during the stretching process in water. , and cannot 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] A polarizing film and a polarizing plate were produced in the same manner as in Example 1, except that the stretching ratio was set to 4.5 times during the aerial auxiliary stretching process, and no underwater stretching process was performed.

>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, calculate the crystallization index and orientation function of the PVA-based resin layer after the aerial stretching process according to the above-mentioned (1) and (2), calculate the thickness variation of the polarizing film according to the above-mentioned (3), and calculate according to the above-mentioned ( 4) Calculate and evaluate the optical properties of the polarizer. In addition, it was confirmed whether the polarizing plates of Examples and Comparative Examples were applied to image display devices without streaks or unevenness. List the results 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 optical properties of the polarizing plates of Comparative Examples 1 and 4 are low, and the polarizing plates of Comparative Examples 1 and 2 have visible streaks and unevenness. Under the manufacturing conditions of Comparative Example 3, the laminate would be broken during stretching in water, and even a polarizing film could not be produced. In contrast, the polarizing plates of Examples 1 and 2 had excellent optical characteristics, and no streaks were observed.

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‧‧‧1st protective layer

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

100‧‧‧偏光板 100‧‧‧polarizer

Claims (1)

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；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；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 a polarizing film, comprising the steps of: 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 aerial stretching on the aforementioned laminate Treatment and dyeing treatment; after the above-mentioned aerial stretching treatment, it further includes performing underwater stretching treatment on the aforementioned laminate; the stretching ratio of the aforementioned aerial stretching treatment is more than 3.0 times, and the aforementioned underwater stretching treatment The stretching ratio is less than 1.8 times; the aforementioned aerial stretching The polyvinyl alcohol-based resin layer after the treatment has a crystallization index calculated by attenuated total reflection spectroscopy of 1.55 to 1.7, and an orientation function of 0.22 to 0.31.
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