TWI789514B - Polarizing plate, polarizing plate coil, and method for manufacturing polarizing film - Google Patents

Polarizing plate, polarizing plate coil, and method for manufacturing polarizing film Download PDF

Info

Publication number
TWI789514B
TWI789514B TW108113066A TW108113066A TWI789514B TW I789514 B TWI789514 B TW I789514B TW 108113066 A TW108113066 A TW 108113066A TW 108113066 A TW108113066 A TW 108113066A TW I789514 B TWI789514 B TW I789514B
Authority
TW
Taiwan
Prior art keywords
polarizing film
stretching
pva
based resin
treatment
Prior art date
Application number
TW108113066A
Other languages
Chinese (zh)
Other versions
TW201945202A (en
Inventor
後藤周作
Original Assignee
日商日東電工股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 日商日東電工股份有限公司 filed Critical 日商日東電工股份有限公司
Publication of TW201945202A publication Critical patent/TW201945202A/en
Application granted granted Critical
Publication of TWI789514B publication Critical patent/TWI789514B/en

Links

Images

Classifications

    • 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
    • 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
    • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
    • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
    • 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
    • B29C35/00—Heating, cooling or curing, e.g. crosslinking or vulcanising; Apparatus therefor
    • B29C35/02—Heating or curing, e.g. crosslinking or vulcanizing during moulding, e.g. in a mould
    • B29C35/0277—Apparatus with continuous transport of the material to be cured
    • 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
    • B29C37/00—Component parts, details, accessories or auxiliary operations, not covered by group B29C33/00 or B29C35/00
    • B29C37/005—Compensating volume or shape change during moulding, in general
    • 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
    • B29C55/023—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets using multilayered plates or sheets
    • B29C55/026—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets using multilayered plates or sheets of preformed plates or sheets coated with a solution, a dispersion or a melt of thermoplastic material
    • 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
    • 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

Abstract

本發明可提供一種具有優異光學特性且光學特性參差經抑制之偏光板。本發明之偏光板，具有偏光膜及配置於該偏光膜之至少一側的保護層，且該偏光膜之厚度為8μm以下，單體透射率為48%以上，偏光度為85%以上；並且，偏光板之50cm2 之區域內的單體透射率的最大值與最小值之差為0.5%以下。本發明之另一偏光板，具有偏光膜及配置於該偏光膜之至少一側的保護層，且該偏光膜之厚度為8μm以下，單體透射率為48%以上，偏光度為85%以上；並且，偏光板之寬度為1000mm以上，且沿寬度方向之位置的單體透射率的最大值與最小值之差為1%以下。The present invention can provide a polarizing plate with excellent optical characteristics and suppressed variation in optical characteristics. The polarizing plate of the present invention has a polarizing film and a protective layer disposed on at least one side of the polarizing film, and the polarizing film has a thickness of 8 μm or less, a single transmittance of 48% or more, and a degree of polarization of 85% or more; and , The difference between the maximum value and the minimum value of the single transmittance in the area of 50 cm 2 of the polarizing plate is 0.5% or less. Another polarizing plate of the present invention has a polarizing film and a protective layer disposed on at least one side of the polarizing film, and the polarizing film has a thickness of 8 μm or less, a single transmittance of 48% or more, and a degree of polarization of 85% or more and, the width of the polarizing plate is more than 1000mm, and the difference between the maximum value and the minimum value of the single transmittance at the position along the width direction is 1% or less.

Description

偏光板、偏光板捲材、及偏光膜之製造方法Polarizing plate, polarizing plate coil, and method for manufacturing polarizing film

本發明係關於一種偏光板、偏光板捲材及偏光膜之製造方法。The invention relates to a manufacturing method of a polarizing plate, a polarizing plate coil and a polarizing film.

發明背景 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)。該等面板具有反射性高的金屬層，故而容易產生外光反射或倒映出背景等問題。而已知此時將具有偏光膜與λ/4板之圓偏光板設置於視辨側，可防止該等問題。作為偏光膜之製造方法，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，其次施以染色處理，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。而且，若隨顯示面板之性能提升而抑制壓低面板之反射率，則偏光度之要求特性降低，便需要透射率更高的偏光板。然而，以往欲在目前既有的薄型偏光膜提高透射率時，因發生PVA系樹脂溶解等問題而未能做出得以承受光學應用的薄膜。Background of the invention 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. These panels have a highly reflective metal layer, so they are prone to problems such as reflection of external light or reflection of the background. However, it is known that setting the circular polarizing plate with the polarizing film and the λ/4 plate on the viewing side can prevent these problems. As a method for producing a polarizing film, for example, a method of extending a laminate having a resin substrate and a polyvinyl alcohol (PVA) resin layer, followed by dyeing to obtain a polarizing film on the resin substrate has been proposed ( 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. Moreover, if the reflectance of the display panel is suppressed as the performance of the display panel is improved, the required characteristic of the degree of polarization is lowered, and a polarizing plate with higher transmittance is required. However, in the past, when trying to increase the transmittance of the existing thin polarizing film, it was not possible to make a film that can withstand optical applications due to problems such as dissolution of the PVA-based resin.

先前技術文獻 專利文獻 專利文獻1：日本專利特開第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 本發明係為了解決上述以往之課題而成者，主要目的在於提供一種具有優異光學特性且光學特性之參差經抑制之偏光板、偏光板捲材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 conventional problems, and its main purpose is to provide a polarizing plate having excellent optical properties and suppressed variations in optical properties, a polarizing plate coil, and a method for manufacturing the polarizing film.

用以解決課題之手段 本發明之偏光板，具有偏光膜及配置於該偏光膜之至少一側的保護層，且該偏光膜之厚度為8μm以下，單體透射率為48%以上，偏光度為85%以上；並且，偏光板之50cm2 之區域內的單體透射率的最大值與最小值之差為0.5%以下。 本發明之另一偏光板，具有偏光膜及配置於該偏光膜之至少一側的保護層，且該偏光膜之厚度為8μm以下，單體透射率為48%以上，偏光度為85%以上；並且，偏光板之寬度為1000mm以上，且沿寬度方向之位置的單體透射率的最大值與最小值之差為1%以下。 在一實施形態中，上述偏光膜之單體透射率為50%以下，且偏光度為92%以下。 根據本發明之另一面向係提供一種偏光板捲材。該偏光板捲材係將上述偏光板捲繞成捲狀而成。 根據本發明之另一面向係提供一種偏光膜之製造方法。該製造方法係製造厚度為8μm以下、單體透射率為48%以上、偏光度為85%以上之偏光膜之方法，且該製造方法包含下列步驟：於長條狀熱塑性樹脂基材單側形成含有鹵化物與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延伸倍率為2.0倍以上之空中輔助延伸處理、染色處理、水中延伸處理與乾燥收縮處理，該乾燥收縮處理係將前述積層體沿長邊方向輸送的同時進行加熱，藉此使其於寬度方向收縮2%以上。 在一實施形態中，上述聚乙烯醇系樹脂層中之上述鹵化物的含量，相對於上述聚乙烯醇系樹脂100重量份為5重量份~20重量份。 在一實施形態中，上述乾燥收縮處理步驟為使用加熱輥進行加熱之步驟。 在一實施形態中，上述加熱輥之溫度為60℃~120℃，且進行上述乾燥收縮處理所得之上述積層體的寬度方向之收縮率為2%以上。Means for Solving the Problems The polarizing plate of the present invention has a polarizing film and a protective layer arranged on at least one side of the polarizing film, and the thickness of the polarizing film is 8 μm or less, the single transmittance is 48% or more, and the degree of polarization is 85% or more; and the difference between the maximum value and the minimum value of the single transmittance in the 50cm 2 region of the polarizing plate is 0.5% or less. Another polarizing plate of the present invention has a polarizing film and a protective layer disposed on at least one side of the polarizing film, and the polarizing film has a thickness of 8 μm or less, a single transmittance of 48% or more, and a degree of polarization of 85% or more and, the width of the polarizing plate is more than 1000mm, and the difference between the maximum value and the minimum value of the single transmittance at the position along the width direction is 1% or less. In one embodiment, the single transmittance of the polarizing film is 50% or less, and the degree of polarization is 92% or less. Another aspect of the present invention is to provide a polarizer roll. This polarizing plate roll material is formed by winding the above-mentioned polarizing plate into a roll shape. According to another aspect of the present invention, a method for manufacturing a polarizing film is provided. The production method is a method for producing a polarizing film with a thickness of 8 μm or less, a single transmittance of 48% or more, and a polarization degree of 85% or more, and the production method includes the following steps: A laminate is made of a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin; and, the above-mentioned laminate is sequentially subjected to an aerial auxiliary stretching treatment with a stretching ratio of 2.0 times or more, a dyeing treatment, and an underwater stretching treatment The dry shrinkage treatment is to heat the above-mentioned laminated body while transporting it along the longitudinal direction, thereby causing it to shrink by 2% or more in the width direction. In one embodiment, the content of the halide in the polyvinyl alcohol-based resin layer is 5 parts by weight to 20 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol-based resin. In one embodiment, the drying shrinkage treatment step is a step of heating using a heating roll. In one embodiment, the temperature of the heating roll is 60° C. to 120° C., and the shrinkage rate of the laminate obtained by performing the drying shrinkage treatment in the width direction is 2% or more.

發明效果 依據本發明，可提供一種具有優異光學特性並且光學特性參差經抑制之偏光板，且該偏光板具有厚度為8μm以下、單體透射率為48%以上、偏光度為85%以上之偏光膜。Invention effect According to the present invention, it is possible to provide a polarizing plate with excellent optical properties and suppressed variation in optical properties, and the polarizing plate has a polarizing film with a thickness of 8 μm or less, a single transmittance of 48% or more, and a degree of polarization of 85% or more.

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.偏光板 圖1為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其中一側的第1保護層20、及配置於偏光膜10另一側的第2保護層30。偏光膜之厚度為8μm以下，單體透射率為48%以上，偏光度為85%以上。亦可省略第1保護層20及第2保護層30中其中一個保護層。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偏光膜之樹脂基材(將於後述)。A. 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 thickness of the polarizing film is less than 8 μm, the single transmittance is more than 48%, and the degree of polarization is more than 85%. 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 (to be described later) used for manufacturing a polarizing film.

偏光板可為長條狀，亦可為薄片狀。當偏光板為長條狀時，宜將其捲繞成捲狀而製成偏光板捲材。則偏光板具有優異光學特性並且光學特性之參差亦小。在一實施形態中，偏光板之寬度為1000mm以上，且其沿寬度方向之位置的單體透射率之最大值與最小值之差(D1)為1%以下。D1之上限宜為0.8%，且較宜為0.6%。D1越小越好，惟其下限例如為0.01%。只要D1在上述範圍內，即可工業化地生產具有優異光學特性之偏光板。在另一實施形態中，偏光板之50cm2 區域內的單體透射率之最大值與最小值之差(D2)為0.5%以下。D2之上限宜為0.25%，且較宜為0.15%。D2越小越好，惟其下限例如為0.01%。只要D2在上述範圍內，即可在將偏光板用於影像顯示裝置時抑制顯示畫面之亮度參差。The polarizing plate can be strip-shaped or thin-sheet-shaped. When the polarizing plate is long, it is preferably wound into a roll to make a polarizing plate roll. Then the polarizing plate has excellent optical properties and the variation of optical properties is also small. In one embodiment, the width of the polarizing plate is 1000 mm or more, and the difference (D1) between the maximum value and the minimum value of the single transmittance at the position along the width direction is 1% or less. The upper limit of D1 is preferably 0.8%, and more preferably 0.6%. The smaller D1 is, the better, but its lower limit is, for example, 0.01%. As long as D1 is within the above range, polarizing plates with excellent optical properties can be industrially produced. In another embodiment, the difference (D2) between the maximum value and the minimum value (D2) of the single transmittance in the 50 cm 2 region of the polarizing plate is 0.5% or less. The upper limit of D2 is preferably 0.25%, and more preferably 0.15%. The smaller D2 is, the better, but its lower limit is, for example, 0.01%. As long as D2 is within the above-mentioned range, it is possible to suppress the brightness variation of the display screen when the polarizing plate is used in an image display device.

A-1.偏光膜 偏光膜如上述，厚度為8μm以下，單體透射率為48%以上，偏光度為85%以上。一般而言，單體透射率與偏光度具有抵換關係，故若提升單體透射率則偏光度會降低，而若提升偏光度則單體透射率會降低。因此，以往滿足單體透射率48%以上且偏光度85%以上之光學特性的薄型偏光膜難以供於應用。本發明成果之一係可實現一種薄型偏光膜(偏光板)，其具有單體透射率為48%以上且偏光度為85%以上之優異光學特性，並且光學特性參差業經抑制。所述偏光膜(偏光板)可用於影像顯示裝置，尤其適宜用於有機EL顯示裝置用之圓偏光板。A-1. Polarizing film As mentioned above, the polarizing film has a thickness of 8 μm or less, a single transmittance of 48% or more, and a degree of polarization of 85% or more. Generally speaking, there is a trade-off relationship between the single transmittance and the degree of polarization. Therefore, if the single transmittance is increased, the polarization degree will be reduced, and if the polarization degree is increased, the single transmittance will be reduced. Therefore, it is difficult to apply thin polarizing films that meet the optical characteristics of a single transmittance of 48% or more and a polarization degree of 85% or more. One of the achievements of the present invention is that a thin polarizing film (polarizing plate) can be realized, which has excellent optical characteristics with a single transmittance of more than 48% and a degree of polarization of more than 85%, and the fluctuation of optical characteristics has been suppressed. The polarizing film (polarizing plate) can be used in image display devices, and is especially suitable for circular polarizing plates used in organic EL display devices.

偏光膜的厚度宜為1μm~8μm，1μm~7μm較佳，2μm~5μm更佳。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.

偏光膜宜在波長380nm~780nm之任一波長下顯示吸收二色性。偏光膜的單體透射率宜為50%以下。偏光膜之偏光度宜為86%以上，較宜為87%以上，更宜為88%以上。另一方面，偏光度的上限宜為92%。上述單體透射率，代表上為利用紫外線-可見光分光光度計測定並經視感度補償的Y值。上述偏光度，代表上為依據利用紫外線-可見光分光光度計測定並經視感度補償的平行透射率Tp及正交透射率Tc，以下述式求得。 偏光度(%)={(Tp-Tc)/(Tp+Tc)}1/2 ×100The polarizing film should exhibit absorption dichroism at any wavelength between 380nm and 780nm. The monomer transmittance of the polarizing film is preferably 50% or less. The degree of polarization of the polarizing film should be above 86%, more preferably above 87%, more preferably above 88%. On the other hand, the upper limit of the degree of polarization is preferably 92%. The above-mentioned monomer transmittance is representatively the Y value measured by ultraviolet-visible spectrophotometer and compensated by visual sensitivity. The above-mentioned degree of polarization is representatively obtained by the following formula based on the parallel transmittance Tp and the cross transmittance Tc measured with an ultraviolet-visible spectrophotometer and compensated for visual sensitivity. Degree of polarization (%)={(Tp-Tc)/(Tp+Tc)} 1/2 ×100

在一實施形態中，8μm以下的薄型偏光膜之透射率在代表上係以偏光膜(表面之折射率：1.53)與保護薄膜(折射率：1.50)之積層體為測定對象，使用紫外線可見光分光光度計來測定。因應偏光膜表面之折射率及/或保護薄膜之與空氣界面接觸的表面之折射率，各層在界面上的反射率會有所變化，結果會有透射率之測定值產生變化之情形。因此，舉例而言在使用折射率非1.50之保護薄膜時，亦可因應保護薄膜之與空氣界面接觸的表面之折射率來校正透射率之測定值。具體上，透射率之校正值C係用和保護薄膜與空氣層之界面的透射軸平行的偏光之反射率R1 (透射軸反射率)，以下式表示。 C=R1 -R0 R0 =((1.50-1)2 /(1.50+1)2 )×(T1 /100) R1 =((n1 -1)2 /(n1 +1)2 )×(T1 /100) 在此，R0 係使用折射率為1.50之保護薄膜時的透射軸反射率，n1 為所用保護薄膜之折射率，T1 為偏光膜之透射率。舉例而言，在使用表面折射率為1.53之基材(環烯烴系薄膜、附硬塗層之薄膜等)作為保護薄膜時，校正量C即為約0.2%。此時，將測定而得之透射率加上0.2%，可換算成使用表面折射率為1.50之保護薄膜時之透射率。另，經依上述式進行計算，在使偏光膜之透射率T1變化了2%時之校正值C的變化量為0.03%以下，故而偏光膜之透射率對校正值C之值的影響是有限的。又，在保護薄膜具有表面反射以外之吸收時，可依吸收量來進行適當的校正。In one embodiment, the transmittance of a thin polarizing film of 8 μm or less is typically measured using a laminate of a polarizing film (refractive index of the surface: 1.53) and a protective film (refractive index: 1.50) using ultraviolet-visible light spectroscopy. photometer to measure. Due to the refractive index of the surface of the polarizing film and/or the refractive index of the surface of the protective film in contact with the air interface, the reflectance of each layer on the interface will change, resulting in a change in the measured value of the transmittance. Therefore, for example, when using a protective film with a refractive index other than 1.50, the measured value of the transmittance can also be corrected according to the refractive index of the surface of the protective film in contact with the air interface. Specifically, the corrected value C of the transmittance is represented by the following formula using the reflectance R 1 (transmission axis reflectance) of polarized light parallel to the transmission axis of the interface between the protective film and the air layer. C=R 1 -R 0 R 0 =((1.50-1) 2 /(1.50+1) 2 )×(T 1 /100) R 1 =((n 1 -1) 2 /(n 1 +1) 2 )×(T 1 /100) Here, R 0 is the transmission axis reflectance when a protective film with a refractive index of 1.50 is used, n 1 is the refractive index of the protective film used, and T 1 is the transmittance of the polarizing film. For example, when using a substrate with a surface refractive index of 1.53 (cycloolefin film, hard-coated film, etc.) as a protective film, the correction amount C is about 0.2%. At this time, add 0.2% to the measured transmittance to convert it to the transmittance when using a protective film with a surface refractive index of 1.50. In addition, after calculating according to the above formula, when the transmittance T1 of the polarizing film is changed by 2%, the change of the correction value C is less than 0.03%, so the influence of the transmittance of the polarizing film on the value of the correction value C is limited. of. Also, when the protective film has absorption other than surface reflection, appropriate correction can be made according to the amount of absorption.

偏光膜可採用任意且適當的偏光膜。偏光膜代表上是使用二層以上之積層體製作而得。As the polarizing film, any appropriate polarizing film can be used. Polarizing film is typically produced using a laminate of two or more layers.

使用積層體而獲得之偏光膜的具體例，可舉出使用樹脂基材及塗佈形成於該樹脂基材之PVA系樹脂層的積層體而獲得之偏光膜。使用樹脂基材及塗佈形成於該樹脂基材之PVA系樹脂層的積層體而獲得之偏光膜，例如可以藉由以下來製作：將PVA系樹脂溶液塗佈於樹脂基材，並使其乾燥而於樹脂基材上形成PVA系樹脂層，以獲得樹脂基材與PVA系樹脂層的積層體；以及將該積層體延伸及染色而將PVA系樹脂層製成偏光膜。本實施形態中，延伸代表上包含使積層體浸漬於硼酸水溶液中並進行延伸。而且，視需要，延伸可更進一步地包含在硼酸水溶液中進行延伸前以高溫(例如95℃以上)將積層體進行空中延伸。可以直接使用所得之樹脂基材/偏光膜的積層體(亦即，可以樹脂基材作為偏光膜的保護層)，或亦可從樹脂基材/偏光膜之積層體剝離樹脂基材，並於該剝離面依目的積層任意且適當的保護層後來使用。所述偏光膜之製造方法的詳細內容，例如記載於日本專利特開2012-73580號公報。本說明書中援用該公報之其整體的記載作為參考。Specific examples of the polarizing film obtained using a laminate include a polarizing film obtained using a resin substrate and a laminate of a PVA-based resin layer coated and formed on the resin substrate. A polarizing film obtained by using a laminate of a resin base material and a PVA-based resin layer coated and formed on the resin base material can be produced, for example, by applying a PVA-based resin solution to a resin base material, and making it drying and forming a PVA-based resin layer on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; and stretching and dyeing the laminate to make the PVA-based resin layer into a polarizing film. In this embodiment, stretching typically includes immersing the laminate in an aqueous solution of boric acid and stretching it. If necessary, the stretching may further include stretching the laminate in air at a high temperature (for example, 95° C. or higher) before stretching in an aqueous boric acid solution. The laminate of the obtained resin substrate/polarizing film can be directly used (that is, the resin substrate can be used as a protective layer of the polarizing film), or the resin substrate can be peeled off from the laminate of the resin substrate/polarizing film, and This peeled surface is used after laminating an arbitrary and appropriate protective layer according to the purpose. The details of the manufacturing method of the said polarizing film are described in Unexamined-Japanese-Patent No. 2012-73580, for example. In this specification, the entire description of this publication is incorporated by reference.

本發明之偏光膜之製造方法包含下列步驟：於長條狀熱塑性樹脂基材之單側形成含有鹵化物與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延伸倍率為2.0倍以上之空中輔助延伸處理、染色處理、水中延伸處理與乾燥收縮處理，該乾燥收縮處理係將上述積層體沿長邊方向輸送的同時進行加熱，藉此使其於寬度方向收縮2%以上。藉此可提供一種具有優異光學特性並且光學特性之參差經抑制的偏光膜，該偏光膜之厚度為8μm以下，單體透射率為48%以上，且偏光度為85%以上。亦即，藉由導入輔助延伸，即便在熱塑性樹脂上塗佈PVA時，仍可提高PVA之結晶性而能夠達成高度之光學特性。並且，藉由在事前同時提高PVA之定向性，可在後續染色步驟及延伸步驟浸漬於水中時，防止PVA之定向性的降低或溶解等的問題，而能夠達成高度之光學特性。並且，當將PVA系樹脂層浸漬於液體時，相較於PVA系樹脂層不含鹵化物的情況，可以抑制聚乙烯醇分子之定向的紊亂以及定向性的降低。藉此，可以提升經染色處理及水中延伸處理等將積層體浸漬於液體來進行之處理步驟所獲得之偏光膜的光學特性。而且，藉由利用乾燥縮處理使積層體在寬度方向上收縮，可提升光學特性。The manufacturing method of the polarizing film of the present invention comprises the following steps: forming a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin on one side of a long thermoplastic resin substrate to form a laminate; and, The above-mentioned laminate is sequentially subjected to air-assisted stretching treatment with an elongation ratio of 2.0 times or more, dyeing treatment, underwater stretching treatment, and drying shrinkage treatment. Make it shrink by more than 2% in the width direction. Thereby, a polarizing film with excellent optical properties and suppressed variation in optical properties can be provided, the thickness of the polarizing film is 8 μm or less, the single transmittance is 48% or more, and the degree of polarization is 85% or more. That is, by introducing auxiliary stretching, even when PVA is coated on a thermoplastic resin, the crystallinity of PVA can be improved and high optical characteristics can be achieved. In addition, by simultaneously improving the orientation of PVA in advance, it is possible to prevent problems such as reduction of orientation of PVA or dissolution during the subsequent dyeing step and stretching step when it is immersed in water, and high optical characteristics can be achieved. In addition, when the PVA-based resin layer is immersed in a liquid, the disorder of the orientation of the polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to the case where the PVA-based resin layer does not contain a halide. Thereby, the optical characteristic of the polarizing film obtained by the process step which immerses a laminated body in liquid, such as dyeing process and underwater stretching process, can be improved. Furthermore, optical characteristics can be improved by shrinking the laminate in the width direction by drying shrinkage treatment.

A-2.保護層 第1及第2保護層是以可作為偏光膜之保護層使用之任意且適當的薄膜來形成。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、聚脂系、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。其他亦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及腈基的熱塑性樹脂之樹脂組成物，且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。A-2. Protective layer The first and second protective layers are formed of any appropriate thin 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 and nitrile group in the side chain can be used, and For example, a resin composition having an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer is 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。此外，當施行有表面處理時，外側保護層之厚度是包含表面處理層之厚度的厚度。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 is a thickness including the thickness of the surface treatment layer.

在將偏光板100應用於影像顯示裝置時被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，內側保護層是具有任意且適當的相位差值的相位差層。此時，相位差層之面內相位差Re(550)是例如110nm~150nm。「Re(550)」是23℃下以波長550nm之光所測定的面內相位差，可藉由式：Re=(nx-ny)×d來求出。此處，「nx」為面內之折射率為最大方向(亦即慢軸方向)的折射率，「ny」為於面內與慢軸正交之方向(亦即快軸方向)的折射率，「nz」為厚度方向的折射率，「d」為層(薄膜)的厚度(nm)。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. At this time, the in-plane retardation Re(550) of the retardation layer is, for example, 110 nm to 150 nm. "Re(550)" is the in-plane retardation measured with light with a wavelength of 550nm at 23°C, and can be obtained by the formula: Re=(nx-ny)×d. Here, "nx" is the refractive index in the direction where the in-plane refractive index is maximum (that is, the direction of the slow axis), and "ny" is the refractive index in the direction that is perpendicular to the slow axis in the plane (that is, the direction of the fast axis) , "nz" is the refractive index in the thickness direction, and "d" is the thickness (nm) of the layer (thin film).

B.偏光膜之製造方法 本發明之一實施形態之偏光膜之製造方法包含下列步驟：於長條狀熱塑性樹脂基材之單側形成含有鹵化物與聚乙烯醇系樹脂(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，對積層體依序施行延伸倍率為2.0倍以上之空中輔助延伸處理、染色處理、水中延伸處理與乾燥收縮處理，該乾燥收縮處理係將積層體在沿長邊方向輸送的同時進行加熱，藉此使其於寬度方向收縮2%以上。相對於PVA系樹脂100重量份，PVA系樹脂層中之鹵化物的含量宜為5重量份~20重量份。乾燥收縮處理宜使用加熱輥進行處理，且加熱輥之溫度宜為60℃~120℃。積層體因乾燥收縮處理所行之寬度方向的收縮率宜在2%以上。根據上述製造方法可製得在上述A項所說明之偏光膜。尤其是藉由下述方式可製得具有優異光學特性(代表上為單體透射率及偏光度)並且光學特性之參差經抑制的偏光膜：製作包含含有鹵化物之PVA系樹脂層的積層體後，將上述積層體之延伸設為包含空中輔助延伸及水中延伸的多階段延伸，再將延伸後之積層體以加熱輥進行加熱。具體而言，在乾燥收縮處理步驟中使用加熱輥，可在輸送積層體的同時使積層體整體全部均勻收縮。藉此不僅可提升所製得之偏光膜的光學特性，還能穩定生產光學特性優異的偏光膜，並可抑制偏光膜之光學特性(尤其是單體透射率)的參差。B. Manufacturing method of polarizing film A method of manufacturing a polarizing film according to an embodiment of the present invention includes the following steps: forming a polyvinyl alcohol-based resin layer ( PVA-based resin layer) to make a laminate; and, the laminate is sequentially subjected to air-assisted stretching treatment, dyeing treatment, underwater stretching treatment and drying shrinkage treatment with an extension ratio of 2.0 times or more. The body is heated while being conveyed along the lengthwise direction, thereby causing it to shrink by 2% or more in the width direction. The content of the halide in the PVA-based resin layer is preferably 5 to 20 parts by weight relative to 100 parts by weight of the PVA-based resin. The drying shrinkage treatment should be done with heating rollers, and the temperature of the heating rollers should be 60°C~120°C. The shrinkage rate in the width direction of the laminate due to drying shrinkage treatment should be above 2%. The polarizing film described in the above-mentioned item A can be produced according to the above-mentioned manufacturing method. In particular, a polarizing film having excellent optical properties (typically, single transmittance and degree of polarization) and with suppressed variation in optical properties can be produced by producing a laminate including a PVA-based resin layer containing a halide Afterwards, the stretching of the above-mentioned laminate is multi-stage stretching including aerial auxiliary stretching and underwater stretching, and the stretched laminate is heated with a heating roller. Specifically, by using a heating roll in the drying shrinkage treatment step, the entire laminate can be uniformly shrunk while conveying the laminate. In this way, the optical properties of the prepared polarizing film can not only be improved, but also the polarizing film with excellent optical properties can be stably produced, and the variation of the optical properties (especially the single transmittance) of the polarizing film can be suppressed.

B-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以採用任意且適當的方法。較佳的是在熱塑性樹脂積層的表面，藉由塗佈包含鹵化物及PVA系樹脂的塗佈液後使其乾燥，而在熱塑性樹脂基材上形成PVA系樹脂層。如上述，相對於PVA系樹脂100重量份，PVA系樹脂層中之鹵化物的含量宜為5重量份~20重量份。B-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. It is preferable to form a PVA-based resin layer on a thermoplastic resin base material by applying a coating solution containing a halide and a PVA-based resin on the surface of the thermoplastic resin layer and drying it. As mentioned above, the content of the halide in the PVA-based resin layer is preferably 5 to 20 parts by weight relative to 100 parts by weight of the PVA-based resin.

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。上述塗布液之塗布、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以表面處理(例如電暈處理等)，亦可在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.

B-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。若低於20μm，恐難以形成PVA系樹脂層。若超過300μm，例如在後述之水中延伸處理時熱塑性樹脂基材恐需要較長時間來吸水而對延伸造成過大的負荷。B-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 exceeds 300 μm, it may take a long time for the thermoplastic resin substrate to absorb water during the underwater stretching treatment described later, which may cause an excessive load on the stretching.

熱塑性樹脂基材其吸水率宜為0.2%以上，更宜為0.3%以上。熱塑性樹脂基材會吸水，水則可發揮塑化劑的作用進行可塑化。其結果，可以使延伸應力大幅降低，而可以高倍率地延伸。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之尺寸穩定性顯著下降導致所得之偏光膜的外觀劣化等不良情況。又，可防止於水中延伸時基材斷裂或PVA系樹脂層從熱塑性樹脂基材剝離。此外，熱塑性樹脂基材之吸水率例如可以藉由將改質基導入構成材料來調整。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%. Thermoplastic resin substrates absorb water, and water acts as a plasticizer for plasticization. As a result, elongation stress can be significantly 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 such a thermoplastic resin substrate, troubles such as deterioration of the appearance of the obtained polarizing film due to a marked decrease in the dimensional stability of the thermoplastic resin substrate during production can be prevented. In addition, it is possible to prevent the substrate from being broken or the PVA-based resin layer to be peeled off from the thermoplastic resin substrate during stretching in water. 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系樹脂層的結晶化，同時又可充分確保積層體的延伸性。並且，若考慮以水所行之熱塑性樹脂基材的可塑化及順利進行水中延伸，宜為100℃以下，更宜為90℃以下。另一方面，熱塑性樹脂基材的玻璃轉移溫度宜為60℃以上。藉由使用所述熱塑性樹脂基材，可以防止在塗佈、乾燥含有上述PVA系樹脂之塗佈液時熱塑性樹脂基材變形(例如，產生凹凸或下垂、皺褶等)等之不良情況，而良好地製作積層體。又，PVA系樹脂層的延伸可以在適當的溫度(例如，60℃左右)下良好地進行。此外，熱塑性樹脂基材的玻璃轉移溫度例如可以藉由將於構成材料導入改質基之結晶化材料加熱來調整。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 at the same time, the extensibility of the laminate can be sufficiently ensured. In addition, considering the plasticization of the thermoplastic resin substrate by water and the smooth extension in water, it is 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 above-mentioned thermoplastic resin substrate, it is possible to prevent defects such as deformation of the thermoplastic resin substrate (for example, occurrence of unevenness or drooping, wrinkles, etc.) when coating and drying the coating liquid containing the above-mentioned PVA-based resin, and The laminated body was produced well. In addition, the stretching of the PVA-based resin layer can be performed favorably at an appropriate temperature (for example, about 60° C.). In addition, the glass transition temperature of the thermoplastic resin substrate can be adjusted, for example, by heating a crystallized material into which a modifying group is introduced 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、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, 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。作為非晶性之聚對苯二甲酸乙二酯系樹脂的具體例，可舉出更包含異酞酸及/或環己烷二羧酸作為二羧酸之共聚物、以及更包含環己烷二甲醇或二乙二醇作為甘醇之共聚物。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 resins include copolymers further containing isophthalic acid and/or cyclohexane dicarboxylic acid as dicarboxylic acids, and copolymers further containing cyclohexane dicarboxylic acid. Dimethanol or diethylene glycol as a copolymer of glycol.

在較佳之實施形態中，熱塑性樹脂基材是以具有異酞酸單元之聚對苯二甲酸乙二酯系樹脂所構成。原因在於所述熱塑性樹脂基材之延伸性極為優異，而可以抑制延伸時之結晶化。吾等認為這是由於導入異酞酸單元，對主鏈帶來很大的折曲所造成的。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。相對於所有重複單元之合計，異酞酸單元之含有比率宜為0.1莫耳%以上，更宜為1.0莫耳%以上。這是因為可以獲得延伸性極為優異之熱塑性樹脂基材。另一方面，相對於所有重複單元之合計，異酞酸單元之含有比率宜為20莫耳%以下，更宜為10莫耳%以下。藉由設定為所述含有比率，可以在後述之乾燥收縮處理中使結晶化度良好地增加。In a preferred embodiment, the thermoplastic resin substrate is composed of a polyethylene terephthalate resin having an isophthalic acid unit. The reason is that the stretchability of the thermoplastic resin substrate is extremely excellent, and crystallization during stretching can be suppressed. We believe that this is caused by the introduction of isophthalic acid unit, which brings great bending to the main chain. The polyethylene terephthalate resin has a terephthalic acid unit and an ethylene glycol unit. The content rate of the isophthalic acid unit is preferably at least 0.1 mol %, more preferably at least 1.0 mol %, based on the total of all repeating units. This is because a thermoplastic resin base material extremely excellent in 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 crystallinity can be favorably increased in the drying shrinkage treatment described later.

熱塑性樹脂基材亦可事先(形成PVA系樹脂層之前)進行延伸。在一實施形態中，是往長條狀熱塑性樹脂基材的橫方向延伸。橫方向宜為與後述之積層體的延伸方向正交之方向。並且，本說明書中所謂「正交」包含實質上正交的情況。此處，所謂之「實質上正交」包含90°±5.0°之情況，且宜為90°±3.0°，更宜為90°±1.0°。The thermoplastic resin substrate may also be stretched in advance (before forming the PVA-based resin layer). In one embodiment, it extends in the lateral 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 includes substantially orthogonal cases. Here, the so-called "substantially orthogonal" includes the case of 90°±5.0°, and is preferably 90°±3.0°, more preferably 90°±1.0°.

相對於玻璃轉移溫度(Tg)，熱塑性樹脂基材之延伸溫度宜為Tg-10℃~Tg+50℃。熱塑性樹脂基材之延伸倍率宜為1.5倍~3.0倍。Relative to the glass transition temperature (Tg), the stretching temperature of the thermoplastic resin substrate is preferably Tg-10°C~Tg+50°C. The elongation ratio of the thermoplastic resin substrate should be 1.5 times to 3.0 times.

熱塑性樹脂基材之延伸方法可採用任意且適當的延伸方法。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以在一階段中進行，亦可分多階段進行。分多階段進行時，上述之延伸倍率為各階段之延伸倍率之積。As the stretching method of the thermoplastic resin substrate, any appropriate stretching method can be adopted. 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.

B-1-2.塗佈液 塗佈液如上述含有鹵化物及PVA系樹脂。上述塗佈液代表上係已使上述鹵化物及上述PVA系樹脂溶解於溶劑中之溶液。作為溶劑，可舉例如水、二甲基亞碸、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。其等中又以水為佳。相對於溶劑100重量份，溶液之PVA系樹脂濃度宜為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之均勻的塗佈膜。相對於PVA系樹脂100重量份，塗佈液中之鹵化物的含有量為5重量份~20重量份。B-1-2. Coating solution The coating liquid contains a halide and a PVA-based resin as described above. The above-mentioned coating liquid represents a solution in which the above-mentioned halide compound and the above-mentioned PVA-based resin are dissolved in a solvent. Examples of the solvent include water, dimethylsulfide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, etc. Amines such as ethylenediamine and diethylenetriamine. These may be used alone or in combination of two or more. Among them, water is the best. With respect to 100 parts by weight of the solvent, the concentration of the PVA-based resin in the solution is preferably 3 parts by weight to 20 parts by weight. As long as it is the above-mentioned resin concentration, a uniform coating film adhered to the thermoplastic resin substrate can be formed. The content of the halide in the coating liquid is 5 to 20 parts by weight with respect to 100 parts by weight of the PVA-based resin.

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。例如可舉出聚乙烯醇及乙烯-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.

上述鹵化物可採用任意且適當的鹵化物。例如可舉出碘化物及氯化鈉。碘化物例如可舉出碘化鉀、碘化納及碘化鋰。該等中又以碘化鉀為佳。Arbitrary and appropriate halides can be used as the above-mentioned halides. For example, iodide and sodium chloride are mentioned. Examples of iodides include potassium iodide, sodium iodide and lithium iodide. Among these, potassium iodide is preferred.

塗佈液中之鹵化物的量，相對於PVA系樹脂100重量份宜為5重量份~20重量份，並且相對於PVA系樹脂100重量份更宜為10重量份~15重量份。若鹵化物相對於PVA系樹脂100重量份之量超過20重量份，鹵化物會溢出(bleedout)，導致最終所得之偏光膜有白濁的情況。The amount of the halide in the coating solution is preferably 5 to 20 parts by weight relative to 100 parts by weight of the PVA-based resin, and more preferably 10 to 15 parts by weight relative to 100 parts by weight of the PVA-based resin. If the amount of the halide exceeds 20 parts by weight relative to 100 parts by weight of the PVA-based resin, the halide will bleed out, resulting in a white turbidity in the final polarizing film.

一般而言，藉由PVA系樹脂層延伸，PVA系樹脂中之聚乙烯醇分子的定向性會變高，但若將延伸後之PVA系樹脂層浸漬於含水的液體中，聚乙烯醇分子之定向會紊亂，而有定向性降低的情況。尤其是在對熱塑性樹脂與PVA系樹脂層的積層體進行硼酸水中延伸時，為了使熱塑性樹脂之延伸穩定而以比較高的溫度在硼酸水中延伸上述積層體時，上述定向度降低的傾向會十分顯著。例如，相對於一般是以60℃進行PVA薄膜單體在硼酸水中的延伸，A-PET(熱塑性樹脂基材)與PVA系樹脂層之積層體的延伸是在70℃前後之溫度之在較高的溫度下進行，在該情況下，延伸初期之PVA的定向性可能會在利用水中延伸而上升之前的階段即降低。相對於此，製作含有鹵化物之PVA系樹脂層與熱塑性樹脂基材的積層體，並於硼酸水中延伸積層體之前在空氣中進行高溫延伸(輔助延伸)，藉此可以促進輔助延伸後之積層體的PVA系樹脂層中之PVA系樹脂之結晶化。其結果，在將PVA系樹脂層浸漬於液體中時，相較於PVA系樹脂層不含鹵化物的情況，可以抑制聚乙烯醇分子之定向的紊亂以及定向性的降低。藉此，可以提升經染色處理及水中延伸處理等將積層體浸漬於液體來進行之處理步驟所獲得之偏光膜的光學特性。Generally speaking, by stretching the PVA-based resin layer, the orientation of the polyvinyl alcohol molecules in the PVA-based resin becomes higher, but if the stretched PVA-based resin layer is immersed in a liquid containing water, the orientation of the polyvinyl alcohol molecules Orientation will be disturbed, and there are cases where orientation is reduced. In particular, when stretching a laminate of a thermoplastic resin and a PVA-based resin layer in boric acid water, when the laminate is stretched in boric acid water at a relatively high temperature in order to stabilize the stretching of the thermoplastic resin, the above-mentioned tendency to decrease the degree of orientation will be significant. significantly. For example, compared to the general stretching of PVA film monomer in boric acid water at 60°C, the stretching of the laminate of A-PET (thermoplastic resin substrate) and PVA-based resin layer is at a higher temperature around 70°C In this case, the orientation of PVA at the initial stage of stretching may decrease before it is raised by stretching in water. In contrast, a laminate of a PVA-based resin layer containing a halide and a thermoplastic resin substrate is produced, and stretching is carried out in air at a high temperature (assisted stretching) before stretching the laminate in boric acid water, thereby facilitating the laminate after assisted stretching Crystallization of the PVA-based resin in the PVA-based resin layer of the body. As a result, when the PVA-based resin layer is immersed in a liquid, the disorder of the orientation of the polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to the case where the PVA-based resin layer does not contain a halide. Thereby, the optical characteristic of the polarizing film obtained by the process step which immerses a laminated body in liquid, such as dyeing process and underwater stretching process, can be improved.

B-2.空中輔助延伸處理 尤其，為了獲得高度之光學特性，會選擇組合乾式延伸(輔助延伸)及硼酸水中延伸之2段延伸的方法。如2段延伸，藉由導入輔助延伸，可以抑制熱塑性樹脂基材之結晶化並同時進行延伸，而可以解決在後續之硼酸水中延伸中因熱塑性樹脂基材過度的結晶化而造成之延伸性降低的問題，故可以更高倍率地延伸積層體。並且當在熱塑性樹脂基材上塗布PVA系樹脂時，為了抑制熱塑性樹脂基材之玻璃移轉溫度的影響，相較於將PVA系樹脂塗佈於通常之金屬圓筒上的情況，必須降低塗佈溫度，結果可能導致產生PVA系樹脂的結晶化相對變低，而無法獲得充分之光學特性的問題。相對於此，藉由導入輔助延伸，則在將PVA系樹脂塗佈於熱塑性樹脂上時，仍可提高PVA系樹脂之結晶性，而能夠達成高度之光學特性。並且，藉由事前同時提高PVA系樹脂之定向性，可在後續染色步驟及延伸步驟浸漬於水中時，防止PVA系樹脂之定向性的降低及溶解等的問題，而可達成高度的光學特性。B-2. Air Assisted Extended Processing In particular, in order to obtain high optical characteristics, a method of combining dry stretching (assisted stretching) and boric acid water stretching in two stages of stretching is selected. Such as 2-stage stretching, by introducing auxiliary stretching, the crystallization of the thermoplastic resin substrate can be suppressed and stretched at the same time, which can solve the problem of extensibility reduction caused by excessive crystallization of the thermoplastic resin substrate in the subsequent boric acid water stretching problem, it is possible to extend the laminate at a higher magnification. In addition, when coating PVA-based resins on thermoplastic resin substrates, in order to suppress the influence of the glass transition temperature of thermoplastic resin substrates, it is necessary to reduce the amount of coating compared to the case of applying PVA-based resins to ordinary metal cylinders. As a result, the crystallization of the PVA-based resin is relatively low, and sufficient optical properties cannot be obtained. On the other hand, by introducing auxiliary stretching, when the PVA-based resin is coated on the thermoplastic resin, the crystallinity of the PVA-based resin can still be improved, and high optical characteristics can be achieved. Furthermore, by simultaneously improving the orientation of the PVA-based resin in advance, it is possible to prevent problems such as reduction in orientation and dissolution of the PVA-based resin during the subsequent dyeing step and stretching step when it is immersed in water, and high optical characteristics can be achieved.

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，該步驟是將上述積層體沿其長邊方向輸送，同時藉由加熱輥間之周速差而進行延伸。空中延伸處理代表上為包含區域延伸步驟及加熱輥延伸步驟。另，區域延伸步驟及加熱輥延伸步驟之順序並無限定，可以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，可依序進行區域延伸步驟及加熱輥延伸步驟。又，在其他實施形態中，拉幅延伸機是把持薄膜端部，並將拉幅機間之距離朝流動方向擴展而進行延伸(拉幅機間之距離的擴展即為延伸倍率)。此時，寬度方向(相對於流動方向為垂直方向)之拉幅機的距離是設定成可任意接近。較理想的是可設定成相對於流動方向之延伸倍率來利用自由端延伸作接近。在自由端延伸之情況下，是以寬度方向之收縮率=(1/延伸倍率)1/2 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 in which the above-mentioned laminate is conveyed in its longitudinal direction while stretching by using a difference in circumferential speed between the heating rolls. The in-air stretching process typically includes a zone stretching step and a heating roll stretching step. In addition, the sequence of the zone stretching step and the heating roll stretching step is not limited, the zone stretching step may be performed first, and the heating roll 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 may be performed sequentially. In another embodiment, the tenter stretcher holds the end of the film and stretches the film by extending the distance between the tenters toward the flow direction (the increase in the distance between the tenters is the draw ratio). At this time, the distance of the tenter in the width direction (vertical direction with respect to the flow direction) is set so as to be arbitrarily close. Ideally, it can be set so that the extension ratio relative to the flow direction can be approached by extending the free end. In the case of free end extension, the shrinkage rate in the width direction = (1/extension ratio) 1/2 is calculated.

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以與水中延伸之延伸方向略為相同為佳。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. It is better that the extension direction in the aerial auxiliary extension is slightly the same as the extension direction in the water extension.

空中輔助延伸中之延伸倍率宜為2.0倍~3.5倍。組合空中輔助延伸及水中延伸時之最大延伸倍率，相對於積層體之原長宜為5.0倍以上，較佳為5.5倍以上，更佳為6.0倍以上。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 extension magnification in the auxiliary extension in the air should be 2.0 times to 3.5 times. The maximum elongation magnification of the combination of aerial auxiliary elongation and underwater elongation is preferably 5.0 times or more, preferably 5.5 times or more, 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的值。延伸溫度宜為熱塑性樹脂基材之玻璃轉移溫度(Tg)以上，更宜為熱塑性樹脂基材之玻璃轉移溫度(Tg)+10℃以上，尤宜為Tg+15℃以上。另一方面，延伸溫度之上限宜為170℃。在所述溫度下延伸可抑制PVA系樹脂之結晶化快速進展，而可抑制該結晶化所造成的不良情況(例如，因延伸而妨礙PVA系樹脂層之定向)。空中輔助延伸後之PVA系樹脂的結晶化指數宜為1.3~1.8，較宜為1.4~1.7。PVA系樹脂之結晶化指數可用傅立葉轉換紅外光譜光度計，藉由ATR法進行測定。具體上是以偏光作為測定光來實施測定，並用所得光譜之1141cm-1 及1440cm-1 之強度，按下述式算出結晶化指數。 結晶化指數=(IC /IR ) 惟， IC ：入射測定光進行測定時之1141cm-1 的強度 IR ：入射測定光進行測定時之1440cm-1 的強度。The stretching temperature of the in-air stretching can be set to an arbitrary 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) of the thermoplastic resin substrate + 10°C, especially preferably 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, and suppresses disadvantages caused by the crystallization (for example, interruption of orientation of the PVA-based resin layer due to stretching). The crystallization index of the PVA-based resin after air-assisted stretching is preferably 1.3-1.8, more preferably 1.4-1.7. The crystallization index of the PVA-based resin can be measured by the ATR method with a Fourier transform infrared spectrophotometer. Specifically, the measurement was carried out using polarized light as the measurement light, and the crystallization index was calculated according to the following formula using the intensities of 1141 cm -1 and 1440 cm -1 of the obtained spectrum. Crystallization index = (I C /I R ) where, I C : intensity at 1141 cm -1 when measurement is performed with incident measurement light I R : intensity at 1440 cm -1 when measurement is performed with incident measurement light.

B-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可藉由將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PVA浸漬於水中時定向降低。相對於水100重量份，該硼酸水溶液之濃度宜為1重量份~4重量份。不溶解浴(硼酸水溶液)之液溫宜為20℃~50℃。B-3. Insoluble treatment If necessary, insolubilization treatment is performed after the air-assisted stretching treatment and before the underwater stretching treatment or dyeing treatment. Typically, the above-mentioned insolubility treatment can be performed 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 it is 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.

B-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。具體而言，是藉由使碘吸附於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。較理想的是使積層體浸漬於染色液(染色浴)中之方法。其是因為可良好吸附碘之故。B-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 allowing iodine to adsorb 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 preferable. This is because iodine can be well adsorbed.

上述染色液宜為碘水溶液。而相對於水100重量份的碘摻混量宜為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。相對於水100重量份，碘化物之摻混量宜為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，較佳為30秒~90秒。The above-mentioned dyeing solution is preferably iodine aqueous solution. The amount of iodine blended with respect to 100 parts by weight of water is preferably 0.05 parts by weight to 0.5 parts by weight. 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. With respect to 100 parts by weight of water, the blending amount of iodide is preferably 0.1 parts by weight to 10 parts by weight, more preferably 0.3 parts by weight to 5 parts by weight. 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, preferably 30 seconds to 90 seconds.

染色條件(濃度、液溫、浸漬時間)可以使最後所得偏光膜之單體透射率為48%以上且偏光度成為85%以上的方式進行設定。所述染色條件宜使用碘水溶液作為染色液，並將碘水溶液中之碘及碘化鉀之含量的比設為1：5~1：20。碘水溶液中之碘及碘化鉀之含量的比宜為1：5~1：10。藉此，可以獲得具有如上述之光學特性的偏光膜。Dyeing conditions (concentration, liquid temperature, immersion time) can be set so that the monomer transmittance of the finally obtained polarizing film becomes 48% or more and the degree of polarization becomes 85% or more. The dyeing conditions should use iodine aqueous solution as the dyeing solution, and set the ratio of iodine and potassium iodide in the iodine aqueous solution to 1:5~1:20. The content ratio of iodine and potassium iodide in the iodine aqueous solution should be 1:5~1:10. Thereby, a polarizing film having the above-mentioned optical characteristics can be obtained.

進行將積層體浸漬於含有硼酸之處理浴中之處理(代表上為不溶解處理)後接續進行染色處理時，該處理浴所含之硼酸混入染色浴會導致染色浴之硼酸濃度隨時間進行產生變化，結果會有染色性變得不穩定的情況。為了抑制如上述之染色性的不穩定化，相對於水100重量份，染色浴之硼酸濃度的上限宜調整為4重量份，更佳為2重量份。另一方面，相對於水100重量份，染色浴之硼酸濃度的下限宜為0.1重量份，較佳為0.2重量份，更佳為0.5重量份。在一實施形態中，是使用事先摻混了硼酸的染色浴來進行染色處理。藉此，可以減低染色浴中混入上述處理浴之硼酸時其硼酸濃度之變化的比率。相對於水100重量份，事先摻混於染色浴之硼酸的摻混量(亦即，非來自上述處理浴之硼酸的含量)宜為0.1~2重量份，較佳為0.5重量份~1.5重量份。When dyeing is carried out after immersing the laminate in a treatment bath containing boric acid (typically insolubilization treatment), the concentration of boric acid in the dyeing bath will increase over time due to the mixing of boric acid contained in the treatment bath into the dyeing bath. As a result, dyeing properties may become unstable. In order to suppress the destabilization of dyeability as described above, the upper limit of the concentration of boric acid in the dyeing bath is preferably adjusted to 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, preferably 0.2 part by weight, and 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 previously mixed with boric acid. Thereby, when the boric acid of the said treatment bath is mixed in the dyeing bath, the ratio of the change of the boric-acid concentration can be reduced. With respect to 100 parts by weight of water, the blending amount of boric acid previously blended in the dyeing bath (that is, the content of boric acid not from the above-mentioned treatment bath) is preferably 0.1 to 2 parts by weight, preferably 0.5 parts by weight to 1.5 parts by weight share.

B-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將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，可對PVA系樹脂層賦予耐水性，防止在後續之水中延伸中，將PVA浸漬於高溫之水中時定向降低。相對於水100重量份，該硼酸水溶液之濃度宜為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。而相對於水100重量份的碘化物之摻混量宜為1重量份~5重量份。碘化物之具體例如上述。交聯浴(硼酸水溶液)之液溫宜為20℃~50℃。B-5. Cross-linking treatment If necessary, after the dyeing treatment and before the stretching treatment in water, a crosslinking treatment is performed. Typically, the above-mentioned crosslinking treatment can be carried out 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, preventing orientation loss when PVA is 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 relative to 100 parts by weight of water is preferably 1 to 5 parts by weight. 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.

B-6.水中延伸處理 水中延伸處理是將積層體浸漬於延伸浴中來進行。藉由水中延伸處理，可在比上述熱塑樹脂基材或PVA系樹脂層之玻璃轉移溫度(代表上為80℃左右)低的溫度下延伸，而可抑制PVA系樹脂層結晶化的同時又可將之高倍率延伸。其結果，可製造出具有優異光學特性的偏光膜。B-6. Extended treatment in water The underwater stretching treatment is carried out 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 while simultaneously It can be extended with high magnification. 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不同之輥間以單軸延伸的方法)。較理想的是選擇自由端延伸。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 stretched at a fixed end or stretched at a free end (for example, a method of uniaxially stretching a laminate through rolls having different circumferential speeds). It is more ideal to choose the free end extension. 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及不溶解於水的耐水性。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。其結果，可賦予PVA系樹脂層剛性及耐水性，而能良好地延伸，製作具有優異光學特性的偏光膜。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 imparted with rigidity capable of withstanding tension applied during stretching and water resistance 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 it can be stretched well, and a polarizing film having excellent optical properties can be produced.

上述硼酸水溶液宜使硼酸及/或硼酸鹽溶解於溶劑之水而獲得。另一方面，硼酸濃度宜相對於水100重量份為1重量份~10重量份，更宜為3.5重量份~7重量份，尤宜為4重量份~6重量份。藉由令硼酸濃度為1重量份以上，可有效抑制PVA系樹脂層的溶解，而可製造較高特性的偏光膜。此外，除硼酸或硼酸鹽外，亦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 relative to 100 parts by weight of water, more preferably 3.5 to 7 parts by weight, particularly preferably 4 to 6 parts by weight. By making the concentration of boric acid 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. Moreover, the aqueous solution which melt|dissolved boron compound, such as borax, glyoxal, glutaraldehyde, etc. in a solvent other than boric acid or borate, can also be used.

理想係於上述延伸浴(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。相對於水100重量份，碘化物之濃度宜為0.05重量份~15重量份，更宜為0.5重量份~8重量份。Ideally, iodide is mixed in the extension bath (aqueous boric acid solution) described above. 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(延伸浴之浴溫)宜為40℃~85℃，更宜為60℃~75℃。只要為所述溫度，便可抑制PVA系樹脂層溶解，同時又可高倍率延伸。具體上如上述，熱塑性樹脂基材之玻璃轉移溫度(Tg)在形成PVA系樹脂層之關聯下宜為60℃以上。此時，延伸溫度若低於40℃，即使考慮以水將熱塑性樹脂基材可塑化，也恐無法良好延伸。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，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 (bath 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 at the same time, high-magnification stretching can be achieved. Specifically, as described above, the glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 60° C. or higher in connection with the formation of the PVA-based resin layer. At this time, if the stretching temperature is lower than 40° C., even considering that the thermoplastic resin base material can be plasticized with water, it may not be well stretched. On the other hand, the higher the temperature of the stretching bath is, the higher the solubility of the PVA-based resin layer will be, 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.

水中延伸所進行之延伸倍率宜為1.5倍以上，更宜為3.0倍以上。相對於積層體的原長，積層體之總延伸倍率宜為5.0倍以上，更宜為5.5倍以上。藉由達成所述之高延伸倍率，可以製造光學特性極為優異之偏光膜。所述高延伸倍率可採用水中延伸方式(硼酸水中延伸)而達成。The elongation ratio of underwater elongation is preferably 1.5 times or more, more preferably 3.0 times or more. The total elongation ratio of the laminate is preferably at least 5.0 times, more preferably at least 5.5 times, relative to the original length of the laminate. By achieving such a high elongation ratio, a polarizing film with extremely excellent optical characteristics can be produced. The high stretching ratio can be achieved by underwater stretching (boric acid underwater stretching).

B-7.乾燥收縮處理 上述乾燥收縮處理可藉由加熱區域整體而進行之區加熱來實施，亦可藉由加熱輸送輥(使用所謂之加熱輥)來實施(加熱輥乾燥方式)。較理想的是使用該兩者。藉由使用加熱輥而使其乾燥，可有效率地抑制積層體之加熱彎曲，而製造外觀優異之偏光膜。具體而言，在使積層體沿著加熱輥的狀態下進行乾燥，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，即便在較低之乾燥溫度下，仍可良好地增加熱塑性基材之結晶化度。其結果，可增加熱塑性樹脂基材之剛性，成為得以承受PVA系樹脂層因乾燥而收縮的狀態，而可抑制捲曲。又，由於使用加熱輥，可以將積層體維持在平坦的狀態並進行乾燥，因此不僅彎曲還可抑制皺褶的產生。此時，積層體藉由乾燥收縮處理在寬度方向上收縮，可提升光學特性。這是由於可有效提升PVA及PVA/碘錯合體之定向性所致。積層體因乾燥收縮處理所行之寬度方向的收縮率宜為1%~10%，較佳為2%~8%，尤佳為4%~6%。藉由使用加熱輥，可在輸送積層體的同時使其連續性地於寬度方向收縮，而可實現高生產率。B-7. Drying shrinkage treatment The above-mentioned drying shrinkage treatment may be implemented by heating the entire area, or may be implemented by heating the conveying roller (using a so-called heating roller) (heating roller drying method). It is desirable to use both. By drying using a heating roll, the heating deflection of a laminate can be suppressed efficiently, and the polarizing film excellent in appearance can be manufactured. Specifically, drying the laminate in a state along the heating roll can effectively promote the crystallization of the above-mentioned thermoplastic resin substrate to increase the degree of crystallization, and even at a relatively low drying temperature, it can still be well Increase the crystallinity of thermoplastic substrates. As a result, the rigidity of the thermoplastic resin substrate can be increased, and the shrinkage of the PVA-based resin layer due to drying can be tolerated, thereby suppressing curling. Moreover, since the laminated body can be dried while being maintained in a flat state by using the heating roll, not only bending but also generation of wrinkles can be suppressed. At this time, the laminate is shrunk in the width direction by drying shrinkage treatment, and optical properties can be improved. This is because it can effectively improve the orientation of PVA and PVA/iodine complex. The shrinkage rate in the width direction of the laminate due to drying and shrinkage treatment is preferably 1%~10%, preferably 2%~8%, and most preferably 4%~6%. By using the heating roller, the laminate can be continuously shrunk in the width direction while being conveyed, and high productivity can be achieved.

圖2為顯示乾燥收縮處理之一例的概略圖。乾燥收縮處理是藉由已加熱至預定溫度的輸送輥R1~R6與導輥G1~G4來輸送積層體200並同時使其乾燥。圖示例中，是以可使PVA樹脂層的面與熱塑性樹脂積層的面交互連續加熱的方式配置輸送輥R1~R6，但例如亦可以僅連續加熱積層體200之其中一面(例如熱塑性樹脂基材面)的方式配置輸送輥R1~R6。Fig. 2 is a schematic view showing an example of drying shrinkage treatment. In the drying shrinkage treatment, the laminated body 200 is conveyed and dried by conveying rollers R1 to R6 and guide rollers G1 to G4 heated to a predetermined temperature. In the illustrated example, the transfer rollers R1 to R6 are arranged in such a way that the surface of the PVA resin layer and the surface of the thermoplastic resin layer can be alternately and continuously heated, but for example, only one of the surfaces of the laminate 200 (such as a thermoplastic resin layer) may be continuously heated. Conveying rollers R1~R6 are arranged in the way of material surface).

可藉由調整輸送輥之加熱溫度(加熱輥之溫度)、加熱輥之數量及接觸加熱輥之時間等，控制乾燥條件。加熱輥之溫度宜為60℃~120℃，更宜為65℃~100℃，尤宜為70℃~80℃。良好地增加熱塑性樹脂之結晶化度可良好地抑制彎曲，並可製造耐久性極為優異之光學積層體。此外，加熱輥之溫度可以利用接觸式溫度計來測定。圖示例中，雖然設置了6個輸送輥，但輸送輥只要多個即無特別限制。輸送輥通常為2個~40個，較佳為設置4個~30個。積層體與加熱輥之接觸時間(總接觸時間)宜為1秒~300秒，較佳為1~20秒，更佳為1~10秒。The drying conditions can be controlled by adjusting the heating temperature of the conveying roller (the temperature of the heating roller), the number of the heating roller and the contact time of the heating roller, etc. The temperature of the heating roller is preferably 60°C~120°C, more preferably 65°C~100°C, especially 70°C~80°C. Properly increasing the crystallinity of thermoplastic resins can suppress warping well and produce optical laminates with excellent durability. In addition, the temperature of the heating roller can be measured with a contact thermometer. In the illustrated example, although six conveying rollers are provided, there is no particular limitation as long as there are multiple conveying rollers. The number of conveying rollers is usually 2 to 40, preferably 4 to 30. The contact time (total contact time) between the laminate and the heating roller is preferably 1 second to 300 seconds, preferably 1 to 20 seconds, more preferably 1 to 10 seconds.

加熱輥可設置於加熱爐(例如烘箱)內，亦可設置於通常之製造生產線(室溫環境下)。較理想的是設置於具備送風機構的加熱爐內。藉由併用加熱輥所進行之乾燥與熱風乾燥，可以抑制加熱輥間之急遽的溫度變化，而可以容易抑制寬度方向之收縮。熱風乾燥的溫度宜為30℃~100℃。又，熱風乾燥時間宜為1秒~300秒。熱風之風速宜為10m/s~30m/s左右。此外，該風速為加熱爐內之風速，可藉由小型葉輪式數位風速計來測定。The heating roller can be installed in a heating furnace (such as an oven), or it can be installed in a normal production line (at room temperature). Preferably, it is installed in a heating furnace equipped with an air supply mechanism. By combining drying with heating rolls and hot air drying, rapid temperature changes between heating rolls can be suppressed, and shrinkage in the width direction can be easily suppressed. The temperature of hot air drying should be 30℃~100℃. Also, the hot air drying time is preferably 1 second to 300 seconds. The wind speed of hot air should be around 10m/s~30m/s. In addition, the wind speed is the wind speed in the heating furnace, which can be measured by a small impeller-type digital anemometer.

B-8.其他處理 較理想的是在水中延伸處理之後且在乾燥收縮處理之前施行洗淨處理。上述洗淨處理代表上可藉由將PVA系樹脂層浸漬於碘化鉀水溶液中來進行。 實施例B-8. Other processing It is preferable to perform the washing treatment after the underwater stretching treatment and before the drying shrinkage 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。各特性之測定方法如以下所述。又，只要無特別明記，實施例及比較例中之「份」及「%」為重量基準。 (1)厚度 使用干涉膜厚計(大塚電子公司製，製品名「MCPD-3000」)進行測定。 (2)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。該等之Ts、Tp及Tc是依JIS Z8701之2度視野(C光源)測定並進行視感度補償所得之Y值。又，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之表面的折射率為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 此外，分光光度計亦可以大塚電子公司製 LPF-200等進行同等之測定。作為一例，針對具有與下述實施例同樣構成之偏光板的試樣1~試樣3，使用V-7100及LPF-200進行測定，並將測得之單體透射率Ts及偏光度P的測定值列於表1。如表1所示，V-7100之單體透射率的測定值與LPF-200之單體透射率的測定值之差為0.1%以下，可知無論使用任一分光光度計皆可獲得同等之測定結果。 [表1]

Figure 02_image001
另，舉例而言，在以具備防眩(AG)之表面處理或具有擴散性能之黏著劑的偏光板為測定對象時，會依分光光度計而獲得不同的測定結果，此時，藉由將以各個分光光度計測定同一偏光板時所得之測定值作為基準進行數值換算，可補償依分光光度計所得測定值之差。 (3)長條狀偏光板的光學特性之參差 從實施例及參考例之長條狀偏光板沿寬度方向以等間隔在5處各位置裁切出測定試樣，再以與上述(2)相同方式測定出5個各測定試樣之中央部分的單體透射率。接著，算出在各測定位置測出之單體透射率之中最大值與最小值之差，並將該值作為長條狀偏光板的光學特性之參差(長條狀偏光板沿寬度方向之位置的單體透射率之最大值與最小值之差)。 (4)薄片狀偏光板的光學特性之參差 從實施例及參考例之長條狀偏光板裁切出100mm×100mm之測定試樣，並求得薄片狀偏光板(50cm2 )的光學特性之參差。具體而言，係以與上述(2)相同方式測定出測定試樣之4邊各邊的中點起算往內側約1.5cm~2.0cm左右之位置及中央部分共計5處之單體透射率。接著，算出在各測定位置所測得之單體透射率中的最大值與最小值之差，並以該值作為薄片狀偏光板之光學特性的參差(在50cm2 區域內之單體透射率的最大值與最小值之差)。 (5)空中輔助延伸後之PVA系樹脂層的結晶化指數 針對空中輔助延伸後之積層體，用傅立葉轉換紅外光譜光度計(Perkin　Elmer公司製，製品名「FT-IR　Frontier」)，並以偏光作為測定光，藉由ATR測定來評估PVA系樹脂層表面。具體上是實施測定，用所得光譜之1141cm-1 及1440cm-1 的強度，按下述式算出結晶化指數。 結晶化指數=(IC /IR ) 惟， IC ：入射測定光進行測定時之1141cm-1 的強度 IR ：入射測定光進行測定時之1440cm-1 的強度Hereinafter, the present invention will be specifically described with examples, but the present invention is not limited by these examples. The measuring method of each characteristic is as follows. In addition, unless otherwise specified, "parts" and "%" in Examples and Comparative Examples are based on weight. (1) Thickness was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"). (2) Monomer transmittance and degree of polarization For the polarizing plates (protective film/polarizing film) of Examples and Comparative Examples, use an ultraviolet-visible light spectrophotometer (V-7100 manufactured by JASCO Corporation) to measure, and measure the Single transmittance Ts, parallel transmittance Tp, and crossed transmittance Tc are used as Ts, Tp, and Tc of the polarizing film, respectively. These Ts, Tp and Tc are measured according to JIS Z8701 with a 2-degree field of view (C light source) and the Y value obtained by performing visual sensitivity compensation. Moreover, the refractive index of the protective film was 1.50, and the refractive index of the surface of the polarizing film opposite to the protective film was 1.53. The degree of polarization P was obtained from the obtained Tp and Tc by the following formula. Degree of polarization P(%)={(Tp-Tc)/(Tp+Tc)} 1/2 ×100 In addition, the spectrophotometer can also be used for the same measurement as LPF-200 manufactured by Otsuka Electronics Co., Ltd. As an example, V-7100 and LPF-200 were used to measure samples 1 to 3 having polarizing plates having the same configuration as the following examples, and the measured single transmittance Ts and polarization degree P The measured values are listed in Table 1. As shown in Table 1, the difference between the measured value of the single-body transmittance of V-7100 and the measured value of the single-body transmittance of LPF-200 is 0.1% or less. It can be seen that the same measurement can be obtained no matter which spectrophotometer is used result. [Table 1]
Figure 02_image001
Also, for example, when measuring a polarizing plate with an anti-glare (AG) surface treatment or an adhesive with diffusing properties, different measurement results will be obtained depending on the spectrophotometer. The measured value obtained by each spectrophotometer when measuring the same polarizing plate is used as the benchmark for numerical conversion, which can compensate for the difference in the measured value obtained by the spectrophotometer. (3) Variation in the optical properties of the strip-shaped polarizing plate Cut out the measurement samples at 5 positions at equal intervals along the width direction of the strip-shaped polarizing plate of the embodiment and the reference example, and then compare with the above (2) The single-body transmittance of the central portion of each of five measurement samples was measured in the same manner. Next, calculate the difference between the maximum value and the minimum value of the single transmittance measured at each measurement position, and use this value as the variance of the optical characteristics of the strip-shaped polarizing plate (the position of the strip-shaped polarizing plate in the width direction The difference between the maximum value and the minimum value of the monomer transmittance). (4) Variation in optical properties of thin-sheet polarizing plates Cut out 100mm×100mm measurement samples from the strip-shaped polarizing plates of Examples and Reference Examples, and obtain the optical properties of thin-sheet polarizing plates (50cm 2 ) uneven. Specifically, in the same manner as in (2) above, the single transmittance was measured at a total of 5 positions about 1.5 cm to 2.0 cm inward from the midpoint of each of the four sides of the measurement sample and the central part. Next, calculate the difference between the maximum value and the minimum value of the single transmittance measured at each measurement position, and use this value as the variation of the optical characteristics of the sheet-shaped polarizing plate (the single transmittance in the 50cm2 area difference between the maximum and minimum values). (5) Crystallization index of PVA-based resin layer after air-assisted stretching For the laminate after aerial-assisted stretching, a Fourier transform infrared spectrophotometer (manufactured by Perkin Elmer, product name "FT-IR Frontier") was used to measure Polarized light was used as measurement light, and the surface of the PVA-based resin layer was evaluated by ATR measurement. Specifically, the measurement was carried out, and the crystallization index was calculated according to the following formula using the intensities of 1141 cm -1 and 1440 cm -1 of the obtained spectra. Crystallization index = (I C /I R ) However, I C : the intensity at 1141 cm -1 when the incident measurement light is measured I R : the intensity at 1440 cm -1 when the incident measurement light is measured

[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)。並對樹脂基材之單面施行電暈處理。 於經將聚乙烯醇(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」以9：1混合而成之PVA系樹脂100重量份中，添加13重量份之碘化鉀，而調製了PVA水溶液(塗佈液)。 藉由將上述PVA水溶液塗佈於樹脂基材之電暈處理面並以60℃進行乾燥，而形成厚度13μm之PVA系樹脂層而製作了積層體。 將所得的積層體在130℃烘箱內於周速相異的輥間沿縱方向(長邊方向)進行自由端單軸延伸2.4倍(空中輔助延伸處理)。 接著，將積層體浸漬於液溫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，將液溫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獲得之碘水溶液)調整其濃度可使最後所製得之偏光膜的單體透射率(Ts)成為48%以上並同時浸漬於其中60秒(染色處理)。 接著，使其於液溫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重量份的硼酸而獲得之硼酸水溶液)中浸漬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5.0重量%)中，一邊在周速相異的輥間沿縱方向(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，將積層體浸漬於液溫20℃的洗淨浴(相對於水100重量份摻混4重量份的碘化鉀而獲得之水溶液)中(洗淨處理)。 之後，在保持於90℃之烘箱中將其乾燥的同時，使其接觸表面溫度保持於75℃之SUS製加熱輥約2秒(乾燥收縮處理)。進行乾燥收縮處理所得之積層體的寬度方向之收縮率為5.2%。 經由以上程序，於樹脂基材上形成了厚度5μm之偏光膜。並且，反覆進行相同步驟而製作出合計10個偏光膜。 2.製作偏光板 在上述所得之各偏光膜的表面(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。然後，從保護薄膜側照射UV光線以使接著劑硬化。接著，將兩端部切開後，將樹脂基材剝離，而獲得10個具有保護薄膜/偏光膜之構成的長條狀偏光板(寬度：1300mm)。[Example 1] 1. Make polarizing film The thermoplastic resin substrate is an amorphous isophthalic acid copolymerized polyethylene terephthalate film (thickness: 100 μm) with a water absorption rate of 0.75% and a Tg of about 75°C. And corona treatment is applied to one side of the resin substrate. PVA made by mixing 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") at a ratio of 9:1 To 100 parts by weight of the resin, 13 parts by weight of potassium iodide was added to prepare an aqueous PVA 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 13-μm-thick PVA-based resin layer to produce a laminate. The obtained laminate was subjected to free-end uniaxial stretching 2.4 times in the longitudinal direction (longitudinal direction) between rolls having different circumferential speeds in an oven at 130° C. (in-air assisted stretching treatment). Next, the laminated body 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 a dyeing bath with a liquid temperature of 30°C (an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with respect to 100 parts by weight of water) so that the single color of the polarizing film finally obtained can be adjusted. The volume transmittance (Ts) becomes 48% or more while dipping in it for 60 seconds (dyeing treatment). Then, it was immersed in a cross-linking bath (with respect to 100 parts by weight of water, 3 parts by weight of potassium iodide and 5 parts by weight of boric acid in an aqueous solution of boric acid) at a liquid temperature of 40° C. for 30 seconds (cross-linking treatment). ). Then, while the laminate was immersed in a boric acid aqueous solution (boric acid concentration: 5.0% by weight) at a liquid temperature of 70°C, it was uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral 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, while drying it in an oven kept at 90° C., it was brought into contact with a SUS heating roller whose surface temperature was kept at 75° C. for about 2 seconds (drying shrinkage treatment). The shrinkage rate in the width direction of the laminate obtained by performing the drying shrinkage treatment was 5.2%. Through the above procedures, a polarizing film with a thickness of 5 μm was formed on the resin substrate. And a total of 10 polarizing films were produced by repeating the same procedure. 2. Make polarizer An acrylic film (surface refractive index: 1.50, 40 μm) was bonded as a protective film to the surface of each polarizing film obtained above (the surface opposite to the resin base material) through an ultraviolet curable adhesive. Specifically, it was applied so that the total thickness of the hardening adhesive was 1.0 μm, and bonded using a rolling mill. Then, UV rays are irradiated from the protective film side to harden the adhesive. Next, after cutting both ends, the resin base material was peeled off, and 10 elongated polarizing plates (width: 1300 mm) which had the structure of a protective film/polarizing film were obtained.

[參考例1] 進行染色處理，使最後所得偏光膜之單體透射率(Ts)為43%以上且小於48%，除此之外依與實施例1相同方式而製作出12個偏光膜及偏光板。[Reference example 1] Dyeing treatment was carried out so that the monomer transmittance (Ts) of the finally obtained polarizing film was more than 43% and less than 48%. In addition, 12 polarizing films and polarizing plates were produced in the same manner as in Example 1.

[比較例1] 未於PVA水溶液(塗佈液)中添加碘化鉀、設空中輔助延伸處理的延伸倍率為1.8倍、及未於乾燥收縮處理中使用加熱輥，除此之外依與實施例1相同方式嘗試製作偏光膜，但於染色處理及水中延伸處理中PVA系樹脂層溶解而未成功製作出單體透射率為48%以上之偏光膜。[Comparative example 1] Potassium iodide was not added to the PVA aqueous solution (coating liquid), the stretching ratio of the air-assisted stretching treatment was set to 1.8 times, and the heating roller was not used in the drying shrinkage treatment, and the polarized light was produced in the same manner as in Example 1. However, the PVA-based resin layer was dissolved during the dyeing process and the water stretching process, and a polarizing film with a monomer transmittance of 48% or more was not successfully produced.

[比較例2] 設空中輔助延伸處理之延伸倍率為1.8倍、及在乾燥收縮處理中未使用加熱輥，除此以外依與實施例1同樣方式嘗試製作17個偏光膜及偏光板，但與比較例1同樣地未成功製作出單體透射率為48%以上之偏光膜。[Comparative example 2] Assuming that the stretching ratio of the auxiliary stretching process in the air was 1.8 times, and the heating roller was not used in the drying shrinkage process, 17 polarizing films and polarizing plates were tried to be produced in the same manner as in Example 1, but the same as in Comparative Example 1. Failed to produce a polarizing film with a single transmittance of more than 48%.

[參考例2] 將依與比較例2相同方式而製得之偏光膜保持於經設定為溫度60℃、濕度90%RH的恆溫恆濕度區域中30分鐘。之後，以與實施例1相同方式而製出偏光板。[Reference example 2] The polarizing film prepared in the same manner as in Comparative Example 2 was kept in a constant temperature and constant humidity area set at a temperature of 60° C. and a humidity of 90% RH for 30 minutes. Thereafter, a polarizing plate was fabricated in the same manner as in Example 1.

針對實施例及比較例之各偏光板測定單體透射率及偏光度。結果顯示於表2及圖3。圖3中，係將實施例1的標點及參考例1的標點的近似曲線以及比較例2的標點的近似曲線繪製成圖來顯示。此外，比較例2的近似曲線係近似3次多項式之近似曲線，並以虛線表示近似曲線的外推部分。The single transmittance and polarization degree were measured about each polarizing plate of an Example and a comparative example. The results are shown in Table 2 and Figure 3. In FIG. 3 , the approximate curve of the punctuation of Example 1, the punctuation of Reference Example 1, and the approximate curve of the punctuation of Comparative Example 2 are plotted and displayed. In addition, the approximate curve of Comparative Example 2 is an approximate curve that approximates a cubic polynomial, and the extrapolated portion of the approximate curve is indicated by a dotted line.

[表2]

Figure 02_image003
[Table 2]
Figure 02_image003

以比較例之製造方法所製得之偏光膜未同時滿足48%以上之單體透射率與85%以上之偏光度。此外，如比較例2之標點的近似曲線所示，比較例2的製造方法中，施行染色處理使單體透射率成為48%以上時，可預測偏光度會小於85%。相對於此，以實施例之製造方法所製得之偏光膜則具有單體透射率為48%以上並且偏光度為85%以上之優異光學特性。The polarizing film produced by the manufacturing method of the comparative example did not satisfy both a single transmittance of more than 48% and a degree of polarization of more than 85%. In addition, as shown in the approximate curve of the punctuation of Comparative Example 2, in the production method of Comparative Example 2, when the dyeing treatment is performed so that the single transmittance becomes 48% or more, the degree of polarization is predicted to be less than 85%. On the other hand, the polarizing film produced by the manufacturing method of the embodiment has excellent optical characteristics such that the single transmittance is 48% or more and the degree of polarization is 85% or more.

針對實施例1及參考例2之各偏光板，測定出長條狀及薄片狀偏光板的光學特性之參差。將結果列於表3。Regarding the polarizing plates of Example 1 and Reference Example 2, the variation in optical characteristics of the strip-shaped and sheet-shaped polarizing plates was measured. List the results in Table 3.

[表3]

Figure 02_image005
[table 3]
Figure 02_image005

以實施例之製造方法所製得之長條狀偏光板的單體透射率之參差為1%以下，且以實施例之製造方法所製得之薄片狀偏光板的單體透射率之參差為0.5%以下，光學特性之參差被抑制在沒有問題的程度。另一方面，經過對偏光膜進行加濕處理之步驟而獲得之參考例的偏光板，不論長條狀及薄片狀其光學特性之參差皆大。The variance of the individual transmittance of the strip-shaped polarizing plate prepared by the manufacturing method of the example is less than 1%, and the variance of the individual transmittance of the sheet-shaped polarizing plate prepared by the manufacturing method of the example is If it is less than 0.5%, the fluctuation of optical characteristics can be suppressed to the extent that there is no problem. On the other hand, the polarizing plate of the reference example obtained through the step of humidifying the polarizing film has large variations in optical characteristics regardless of whether it is in the shape of a strip or a sheet.

而且，針對實施例及比較例之偏光膜根據上述(5)測定空中輔助延伸後之積層體中PVA系樹脂的結晶化指數。並在染色處理或水中延伸處理中確認PVA系樹脂是否有所溶解。將結果列於表4。And the crystallization index of the PVA-type resin in the laminated body after air-assisted stretching was measured about the polarizing film of the Example and the comparative example according to said (5). And confirm whether the PVA-based resin is dissolved in the dyeing treatment or the water stretching treatment. List the results in Table 4.

[表4]

Figure 02_image007
[Table 4]
Figure 02_image007

產業上之可利用性 具有本發明之偏光膜的偏光板可適宜使用在有機EL顯示裝置及無機EL顯示裝置用圓偏光板。Industrial availability The polarizing plate having the polarizing film of the present invention can be suitably used as a circular polarizing plate for organic EL display devices and inorganic EL display devices.

10‧‧‧偏光膜 20‧‧‧第1保護層 30‧‧‧第2保護層 100‧‧‧偏光板 200‧‧‧積層體 G1~G4‧‧‧導輥 R1~R6‧‧‧輸送輥10‧‧‧Polarizing film 20‧‧‧1st protective layer 30‧‧‧Second protective layer 100‧‧‧polarizer 200‧‧‧laminated body G1~G4‧‧‧guide roller R1~R6‧‧‧Conveying roller

圖1係本發明之一實施形態之偏光板的概略截面圖。 圖2係顯示使用加熱輥之乾燥收縮處理之一例的概略圖。 圖3係顯示實施例及比較例製得之偏光板的光學特性之圖表。Fig. 1 is a schematic cross-sectional view of a polarizing plate according to an embodiment of the present invention. Fig. 2 is a schematic diagram showing an example of drying shrinkage treatment using a heating roll. Fig. 3 is a graph showing optical properties of polarizing plates produced in Examples and Comparative Examples.

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 (6)

一種偏光膜之製造方法，該偏光膜之厚度為8μm以下，單體透射率為48%以上，偏光度為85%以上，且該製造方法包含下列步驟：於長條狀熱塑性樹脂基材單側形成聚乙烯醇系樹脂層而製成積層體，其中該聚乙烯醇系樹脂層含有：碘化物或氯化鈉，與聚乙烯醇系樹脂；及對前述積層體依序施行空中輔助延伸處理、染色處理、水中延伸處理與乾燥收縮處理，該乾燥收縮處理係將前述積層體沿長邊方向輸送的同時進行加熱，藉此使其於寬度方向收縮2%以上。 A method for manufacturing a polarizing film, the thickness of the polarizing film is less than 8 μm, the transmittance of a single element is more than 48%, and the degree of polarization is more than 85%, and the manufacturing method includes the following steps: forming a polyvinyl alcohol-based resin layer to produce a laminate, wherein the polyvinyl alcohol-based resin layer contains: iodide or sodium chloride, and a polyvinyl alcohol-based resin; Dyeing treatment, underwater stretching treatment, and drying shrinkage treatment. The drying shrinkage treatment involves heating the above-mentioned laminate while transporting it along the longitudinal direction, thereby shrinking it by more than 2% in the width direction. 如請求項1之偏光膜之製造方法，其中該偏光膜之單體透射率為50%以下，偏光度為92%以下。 The method of manufacturing a polarizing film according to claim 1, wherein the single transmittance of the polarizing film is 50% or less, and the degree of polarization is 92% or less. 如請求項1或2之製造方法，其中前述聚乙烯醇系樹脂層中之前述碘化物或氯化鈉之含量，相對於前述聚乙烯醇系樹脂100重量份為5重量份~20重量份。 The production method according to claim 1 or 2, wherein the content of the iodide or sodium chloride in the polyvinyl alcohol-based resin layer is 5 to 20 parts by weight relative to 100 parts by weight of the polyvinyl alcohol-based resin. 如請求項1或2之製造方法，其中前述空中輔助延伸處理的延伸倍率為2.0倍以上。 The manufacturing method according to claim 1 or 2, wherein the stretching ratio of the above-mentioned air-assisted stretching treatment is 2.0 times or more. 如請求項1或2之製造方法，其中前述乾燥收縮處理步驟為使用加熱輥進行加熱之步驟。 The manufacturing method according to claim 1 or 2, wherein the drying shrinkage treatment step is a heating step using a heating roller. 如請求項5之製造方法，其中前述加熱輥之溫度為60℃~120℃，且進行前述乾燥收縮處理所得之前述積層體的寬度方向之收縮率為2%以上。 The manufacturing method according to claim 5, wherein the temperature of the heating roller is 60°C to 120°C, and the shrinkage rate in the width direction of the laminate obtained by performing the drying shrinkage treatment is 2% or more.
TW108113066A 2018-04-25 2019-04-15 Polarizing plate, polarizing plate coil, and method for manufacturing polarizing film TWI789514B (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2018083653 2018-04-25
JP2018-083653 2018-04-25
JP2018089243A JP7219017B2 (en) 2018-04-25 2018-05-07 Method for manufacturing polarizing film
JP2018-089243 2018-05-07

Publications (2)

Publication Number Publication Date
TW201945202A TW201945202A (en) 2019-12-01
TWI789514B true TWI789514B (en) 2023-01-11

Family

ID=68469092

Family Applications (1)

Application Number Title Priority Date Filing Date
TW108113066A TWI789514B (en) 2018-04-25 2019-04-15 Polarizing plate, polarizing plate coil, and method for manufacturing polarizing film

Country Status (4)

Country Link
JP (1) JP7219017B2 (en)
KR (1) KR20210005013A (en)
CN (1) CN112005144A (en)
TW (1) TWI789514B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112262329A (en) * 2018-06-07 2021-01-22 日东电工株式会社 Polarizing film and polarizing plate with phase difference layer

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003185845A (en) * 2001-09-19 2003-07-03 Nitto Denko Corp Polarizing plate and method for manufacturing the same, and liquid crystal display using the same
TW200417794A (en) * 2003-01-31 2004-09-16 Fuji Photo Film Co Ltd Polarizing plate, production process for polarizing plate, and liquid crystal display device
JP2005326713A (en) * 2004-05-17 2005-11-24 Fuji Photo Film Co Ltd Antireflective polarizing plate, its manufacturing method and image display apparatus using the plate
JP2011047983A (en) * 2009-08-25 2011-03-10 Fujifilm Corp Method of manufacturing optical film and optical film manufactured by the manufacturing method
TW201232065A (en) * 2010-09-09 2012-08-01 Nitto Denko Corp Method of producing thin polarizing film
TW201722685A (en) * 2014-03-14 2017-07-01 Nitto Denko Corp Laminate, stretched laminate, method for manufacturing stretched laminate, method for manufacturing polarizing-film-containing optical-film laminate using same, and polarizing film

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001343521A (en) 2000-05-31 2001-12-14 Sumitomo Chem Co Ltd Polarizing plate and method for manufacturing the same
JP5072747B2 (en) * 2007-07-25 2012-11-14 日東電工株式会社 Manufacturing method of polarizer, polarizer, polarizing plate, optical film, and image display device
JP4929480B2 (en) * 2007-11-19 2012-05-09 日東電工株式会社 Coating liquid for forming polarizing film and polarizing film
WO2019054273A1 (en) * 2017-09-13 2019-03-21 日東電工株式会社 Polarizing plate, polarizing plate roll, and method for producing polarizing film

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003185845A (en) * 2001-09-19 2003-07-03 Nitto Denko Corp Polarizing plate and method for manufacturing the same, and liquid crystal display using the same
TW200417794A (en) * 2003-01-31 2004-09-16 Fuji Photo Film Co Ltd Polarizing plate, production process for polarizing plate, and liquid crystal display device
JP2005326713A (en) * 2004-05-17 2005-11-24 Fuji Photo Film Co Ltd Antireflective polarizing plate, its manufacturing method and image display apparatus using the plate
JP2011047983A (en) * 2009-08-25 2011-03-10 Fujifilm Corp Method of manufacturing optical film and optical film manufactured by the manufacturing method
TW201232065A (en) * 2010-09-09 2012-08-01 Nitto Denko Corp Method of producing thin polarizing film
TW201722685A (en) * 2014-03-14 2017-07-01 Nitto Denko Corp Laminate, stretched laminate, method for manufacturing stretched laminate, method for manufacturing polarizing-film-containing optical-film laminate using same, and polarizing film

Also Published As

Publication number Publication date
JP2019194657A (en) 2019-11-07
CN112005144A (en) 2020-11-27
KR20210005013A (en) 2021-01-13
TW201945202A (en) 2019-12-01
JP7219017B2 (en) 2023-02-07

Similar Documents

Publication Publication Date Title
TWI775940B (en) Polarizing plate, polarizing plate roll material and polarizing film manufacturing method
TWI801599B (en) Polarizing film and method for manufacturing polarizing film
TWI775939B (en) Polarizing plate, polarizing plate roll material and polarizing film manufacturing method
TWI748108B (en) Polarizing film, polarizing plate, and manufacturing method of polarizing film
TWI823856B (en) Polarizing film, polarizing plate, polarizing plate roll material and polarizing film manufacturing method
TWI762667B (en) Polarizing film, polarizing plate, polarizing plate roll, and manufacturing method of polarizing film
CN111095055B (en) Polarizing film, polarizing plate, and method for producing polarizing film
TWI743373B (en) Polarizing film, polarizing plate, and manufacturing method of polarizing film
TWI789514B (en) Polarizing plate, polarizing plate coil, and method for manufacturing polarizing film
TWI801395B (en) Polarizing film, polarizing plate, polarizing plate roll, and method for manufacturing polarizing film
TWI775885B (en) Polarizing plate and polarizing plate coil
CN111095053A (en) Polarizing plate, polarizing plate roll, and method for producing polarizing film
TW202315913A (en) Method of manufacturing polarizing film including a resin film obtaining step, a moisture content adjustment step, and a drying step
TW202316149A (en) Method for manufacturing polarizing film with both high optical properties and excellent appearance
WO2019208181A1 (en) Polarizer, polarizer roll, and method for manufacturing polarizing film
TW202401115A (en) Method for producing polarizing film
TW202348697A (en) Method for producing polarizing film
TW202409619A (en) Manufacturing method of polarizing film
JP2019197204A (en) Polarizing plate and polarizing plate roll