TW202041546A - Polarizing film, polarizing plate and method for manufacturing said polarizing film - Google Patents
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Abstract
Description
本發明係關於偏光膜、偏光板及該偏光膜之製造方法。The present invention relates to a polarizing film, a polarizing plate and a manufacturing method of the polarizing film.
屬代表性影像顯示裝置的液晶顯示器，因其影像形成方式而於液晶單元之兩側配置有偏光膜。偏光膜之製造方法上，舉例而言，目前已提出一種方法，係將具有樹脂基材與聚乙烯醇(PVA)系樹脂層之積層體延伸後，接著實施染色處理而於樹脂基材上製得偏光膜(以專利文獻1為例)。因藉由此方法，可製得厚度薄之偏光膜，有利於近年影像顯示裝置之薄型化而被注目。但是，如上述之薄型偏光膜有容易沿吸收軸方向裂開(易破損)的問題。The liquid crystal display, which is a representative image display device, has polarizing films arranged on both sides of the liquid crystal cell due to its image forming method. As for the manufacturing method of polarizing film, for example, a method has been proposed, which is to extend a laminate with a resin substrate and a polyvinyl alcohol (PVA) resin layer, and then perform dyeing treatment to prepare it on the resin substrate. Polarizing film (take Patent Document 1 as an example). Because of this method, a thin polarizing film can be produced, which is conducive to the thinning of image display devices in recent years and has attracted attention. However, the thin polarizing film as described above has the problem of being easy to crack (easy to break) along the absorption axis.
先前技術文獻 專利文獻 專利文獻1：日本特開2001-343521號公報Prior art literature Patent literature Patent Document 1: Japanese Patent Application Publication No. 2001-343521
發明概要 發明欲解決之課題 本發明係為解決上述過去之課題而產生者，其主要目的為提供一種沿吸收軸方向之破斷受到抑制之偏光膜。Summary of the invention Problems to be solved by the invention The present invention was created to solve the above-mentioned problems in the past, and its main purpose is to provide a polarizing film whose breakage along the absorption axis is suppressed.
用以解決課題之手段 本發明實施型態之偏光膜係由含二色性物質之聚乙烯醇系樹脂薄膜構成，且定向函數為0.30以下。 於一實施型態中，上述偏光膜之厚度為8μm以下。 於一實施型態中，上述偏光膜之單體透射率為40.0%以上，且偏光度為99.0%以上。 於一實施型態中，上述偏光膜之穿刺強度為30gf/μm以上。 本發明另一實施型態之偏光膜係由含二色性物質之聚乙烯醇系樹脂薄膜構成，且穿刺強度為30gf/μm以上。 依據本發明之另一態樣，提供一種偏光板。此偏光板係具有上述偏光膜與配置於該偏光膜至少其中一側的保護層。 依據本發明之另一態樣，提供上述偏光膜之製造方法。該製造方法包含下述步驟：於長條狀之熱塑性樹脂基材的單側，形成含有碘化物或氯化鈉與聚乙烯醇系樹脂之聚乙烯醇系樹脂層以製成積層體；及對該積層體依序實施空中輔助延伸處理、染色處理、水中延伸處理及乾燥收縮處理，該乾燥收縮處理係藉由將積層體一邊朝長度方向輸送一邊加熱以使其寬度方向上收縮2%以上。該空中輔助延伸處理及該水中延伸處理之延伸總倍率相對於該積層體之原長為3.0倍~4.5倍；該空中輔助延伸處理之延伸倍率係較該水中延伸處理之延伸倍率大。Means to solve the problem The polarizing film of the embodiment of the present invention is composed of a polyvinyl alcohol resin film containing a dichroic substance, and the orientation function is 0.30 or less. In one embodiment, the thickness of the polarizing film is 8 μm or less. In one embodiment, the monomer transmittance of the polarizing film is more than 40.0%, and the polarization degree is more than 99.0%. In one embodiment, the puncture strength of the polarizing film is 30 gf/μm or more. The polarizing film of another embodiment of the present invention is composed of a polyvinyl alcohol resin film containing a dichroic substance, and has a puncture strength of 30 gf/μm or more. According to another aspect of the present invention, a polarizing plate is provided. The polarizing plate has the above-mentioned polarizing film and a protective layer disposed on at least one side of the polarizing film. According to another aspect of the present invention, a manufacturing method of the above-mentioned polarizing film is provided. The manufacturing method includes the following steps: forming a polyvinyl alcohol-based resin layer containing iodide or sodium chloride and a polyvinyl alcohol-based resin on one side of the elongated thermoplastic resin substrate to form a laminate; and The layered body is sequentially subjected to air-assisted stretching treatment, dyeing treatment, underwater stretching treatment, and drying shrinking treatment. The drying shrinking treatment is performed by heating the layered body while conveying it in the longitudinal direction to shrink it by 2% or more in the width direction. The total extension magnification of the aerial auxiliary extension treatment and the underwater extension treatment is 3.0 to 4.5 times the original length of the laminate; the extension magnification of the aerial auxiliary extension treatment is greater than that of the underwater extension treatment.
發明之效果 依據本發明，藉由將定向函數設為0.30以下，或將穿刺強度設為30gf/μm以上，可實現沿吸收軸方向之破斷受到抑制之偏光膜。過去以來，定向函數如此小的偏光膜難以得到可接受的光學特性(具代表性者為單體透射率及偏光度)，但依據本發明，便可使如此小的定向函數與可接受的光學特性並存。再者，依據本發明，可使如此大的穿刺強度與可接受的光學特性並存。Effect of invention According to the present invention, by setting the orientation function to 0.30 or less, or setting the puncture strength to 30 gf/μm or more, it is possible to realize a polarizing film with suppressed breaking along the absorption axis. In the past, it was difficult for a polarizing film with such a small orientation function to obtain acceptable optical properties (typically, monomer transmittance and polarization). However, according to the present invention, such a small orientation function and acceptable optical properties can be achieved. Features coexist. Furthermore, according to the present invention, such a large puncture strength can coexist with acceptable optical characteristics.
用以實施發明之型態 以下，對本發明之實施型態進行說明，但本發明並不限定於此等實施型態。Types used to implement the invention Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.
A.偏光膜 本發明之實施型態之偏光膜由含二色性物質(具代表性者為碘、二色性染料)之聚乙烯醇(PVA)系樹脂薄膜構成，且定向函數為0.30以下。如此的構成可以顯著抑制偏光膜沿吸收軸方向裂開(破損)。其結果可得到撓曲性非常優秀之偏光膜(就結果而言為偏光板)。如此的偏光膜(就結果而言為偏光板)，理想上可應用於彎曲之影像顯示裝置，較佳為可彎折之影像顯示裝置，更佳為可折疊之影像顯示裝置。定向函數例如為0.25以下，且0.22以下為佳，0.20以下較佳，0.18以下更佳，0.15以下特佳。定向函數之下限例如可為0.05。若定向函數過小，會有無法得到可接受的單體透射率及/或偏光度的情況。A. Polarizing film The polarizing film of the embodiment of the present invention is composed of a polyvinyl alcohol (PVA) resin film containing dichroic substances (typically iodine and dichroic dyes), and has an orientation function of 0.30 or less. Such a configuration can significantly suppress cracking (breakage) of the polarizing film in the absorption axis direction. As a result, a polarizing film (a polarizing plate as a result) with very excellent flexibility can be obtained. Such a polarizing film (a polarizing plate as a result) is ideally applicable to a curved image display device, preferably a bendable image display device, and more preferably a foldable image display device. The orientation function is, for example, 0.25 or less, and preferably 0.22 or less, preferably 0.20 or less, more preferably 0.18 or less, and particularly preferably 0.15 or less. The lower limit of the orientation function may be 0.05, for example. If the orientation function is too small, it may not be possible to obtain acceptable monomer transmittance and/or polarization.
定向函數(f)例如可使用傅立葉轉換紅外光譜儀(FT-IR)，以偏光作為測定光，進行衰減全反射分光(ATR：attenuated total reflection)測定來求算。具體而言，係在偏光膜之延伸方向相對於測定光之偏光方向為平行及垂直的狀態下實施測定後，用所得之吸收光譜之2941cm-1 之強度，依照下述式算出。於此，強度I係以3330cm-1 作為參考峰並為2941cm-1 /3330cm-1 之值。另外，f＝1時成為完全定向，f＝0時成為隨機。此外，2941cm-1 處之尖峰被認為是因偏光膜中PVA的主鏈(-CH2 -)之振動而造成的吸收。 f＝(3＜cos2 θ＞-1)/2 ＝(1-D)/［c(2D＋1)］ ＝-2×(1-D)/(2D＋1) 惟，c＝(3cos2 β-1)/2中，2941cm-1 之振動時，β＝90°。 θ：分子鏈相對於延伸方向之角度 β：躍遷偶極距相對於分子鏈軸之角度 D＝(I⊥ )/(I// ) (此時，PVA分子越定向，D的值越大) I⊥ ：測定光之偏光方向與偏光膜之延伸方向為垂直時的吸收強度 I// ：測定光之偏光方向與偏光膜之延伸方向為平行時的吸收強度The orientation function (f) can be calculated, for example, by using a Fourier transform infrared spectrometer (FT-IR), using polarized light as the measurement light, and performing attenuated total reflection spectroscopy (ATR: attenuated total reflection) measurement. Specifically, the measurement is performed in a state where the extension direction of the polarizing film is parallel and perpendicular to the polarization direction of the measurement light, and the intensity of the obtained absorption spectrum at 2941 cm -1 is used to calculate according to the following formula. Here, the intensity I takes 3330 cm -1 as the reference peak and is a value of 2941 cm -1 /3330 cm -1 . In addition, when f=1, it becomes fully oriented, and when f=0, it becomes random. In addition, the sharp peak at 2941 cm -1 is considered to be absorption due to the vibration of the main chain (-CH 2 -) of PVA in the polarizing film. f=(3＜cos 2 θ＞-1)/2 =(1-D)/[c(2D＋1)] =-2×(1-D)/(2D＋1) However, c=(3cos 2 β-1 In )/2, when the vibration is 2941cm -1 , β=90°. θ: The angle of the molecular chain relative to the extension direction β: The angle of the transition dipole moment relative to the axis of the molecular chain D=(I ⊥ )/(I // ) (At this time, the more the PVA molecule is oriented, the greater the value of D) I ⊥ ：Measure the absorption intensity when the polarization direction of light is perpendicular to the extension direction of the polarizing film I // ：Measure the absorption intensity when the polarization direction of light and the extension direction of the polarizing film are parallel
偏光膜之厚度以8μm以下為佳、7μm以下較佳、5μm以下更佳、3μm以下特佳、2μm以下最佳。偏光膜之厚度之下限例如可為1μm。偏光膜之厚度於一實施型態中可為2μm~6μm，另一實施型態中可為2μm~4μm，又另一實施型態中可為2μm~3μm，又另一實施型態中可為5.5μm~7.5μm，又另一實施型態中可為6μm~7.2μm。藉由將偏光膜之厚度如所述般做成非常薄，可使熱收縮非常小。推測如此的構成可有助於抑制吸收軸方向之破斷。The thickness of the polarizing film is preferably 8 μm or less, 7 μm or less, more preferably 5 μm or less, particularly preferably 3 μm or less, and most preferably 2 μm or less. The lower limit of the thickness of the polarizing film may be, for example, 1 μm. The thickness of the polarizing film can be 2μm~6μm in one embodiment, 2μm~4μm in another embodiment, 2μm~3μm in another embodiment, and 2μm~3μm in another embodiment. 5.5μm~7.5μm, in another embodiment, it can be 6μm~7.2μm. By making the thickness of the polarizing film very thin as described, the thermal shrinkage can be very small. It is speculated that such a configuration can help to suppress breakage in the direction of the absorption axis.
偏光膜宜於波長380nm~780nm中之任一波長下表現出吸收二色性。偏光膜之單體透射率以40.0%以上為佳、41.0%以上較佳。單體透射率之上限例如可為49.0%。偏光膜之單體透射率於一實施型態中為40.0%~45.0%。偏光膜之偏光度以99.0%以上為佳、99.4%以上較佳。偏光度之上限例如可為99.999%。偏光膜之偏光度於一實施型態中為99.0%~99.99%。依據本發明，儘管如上所述定向函數非常小，亦可實現如此於實際應用上可接受的單體透射率及偏光度。此結果推測為起因於後述製造方法。又，單體透射率在代表性上係使用紫外線可見光分光光度計測定並進行視感度校正後之Y值。偏光度在代表性上係基於使用紫外線可見光分光光度計測定並進行視感度校正後之平行透射率Tp及正交透射率Tc，藉由下式來求算。 偏光度(%)＝｛(Tp-Tc)/(Tp＋Tc)｝1 /2 ×100The polarizing film is suitable to exhibit absorption dichroism at any wavelength from 380nm to 780nm. The monomer transmittance of the polarizing film is preferably 40.0% or more, preferably 41.0% or more. The upper limit of the transmittance of the monomer may be 49.0%, for example. The monomer transmittance of the polarizing film is 40.0%~45.0% in one embodiment. The degree of polarization of the polarizing film is preferably 99.0% or more, preferably 99.4% or more. The upper limit of the degree of polarization may be 99.999%, for example. The degree of polarization of the polarizing film is 99.0%-99.99% in one embodiment. According to the present invention, even though the orientation function is very small as described above, it is possible to achieve such a monomer transmittance and polarization that are acceptable in practical applications. This result is presumably due to the manufacturing method described later. In addition, the transmittance of the monomer is typically the Y value measured with an ultraviolet-visible spectrophotometer and corrected for visual sensitivity. The degree of polarization is typically based on the parallel transmittance Tp and the orthogonal transmittance Tc measured with an ultraviolet-visible spectrophotometer and corrected for visual sensitivity, and is calculated by the following formula. Polarization (%) = {(Tp-Tc)/(Tp＋Tc)} 1 /2 ×100
偏光膜之穿刺強度為30gf/μm以上，以35gf/μm以上為佳、40gf/μm以上較佳、45gf/μm以上更佳、50gf/μm以上特佳。穿刺強度之上限例如可為80gf/μm。藉由將偏光膜之穿刺強度設為如此之範圍，可顯著抑制偏光膜沿吸收軸方向裂開。其結果，可得到撓曲性非常優秀之偏光膜(就結果而言為偏光板)。穿刺強度係表示以預定強度穿刺偏光膜時偏光膜之抗裂性。穿刺強度例如可用下述強度表示：於壓縮試驗機安裝預定穿刺針並將該穿刺針以預定速度對偏光膜穿刺時偏光膜會破裂之強度(破斷強度)。另外，由單位可明瞭，穿刺強度意指偏光膜之每單位厚度(1μm)的穿刺強度。The puncture strength of the polarizing film is 30gf/μm or more, preferably 35gf/μm or more, preferably 40gf/μm or more, more preferably 45gf/μm or more, and particularly preferably 50gf/μm or more. The upper limit of the puncture strength may be 80 gf/μm, for example. By setting the puncture strength of the polarizing film to such a range, the polarizing film can be significantly prevented from splitting along the absorption axis. As a result, a polarizing film (a polarizing plate as a result) with very excellent flexibility can be obtained. Puncture strength refers to the crack resistance of the polarizing film when the polarizing film is pierced with a predetermined strength. The puncture strength can be expressed by, for example, the following strength: the strength (breaking strength) at which the polarizing film will rupture when a predetermined puncture needle is installed in a compression tester and the puncture needle punctures the polarizing film at a predetermined speed. In addition, as understood from the unit, the puncture strength means the puncture strength per unit thickness (1 μm) of the polarizing film.
偏光膜如上所述係由含碘之PVA系樹脂薄膜構成。構成PVA系樹脂薄膜(實質上為偏光膜)之PVA系樹脂宜含有經乙醯乙醯基改質之PVA系樹脂。若以如此之構成，可得到具有所期望之穿刺強度的偏光膜。經乙醯乙醯基改質之PVA系樹脂之摻合量，在設定全部PVA系樹脂為100重量%時，以5重量%~20重量%為佳，8重量%~12重量%較佳。若摻合量於如此範圍內，可使穿刺強度落在較合適的範圍。The polarizing film is composed of a PVA-based resin film containing iodine as described above. The PVA-based resin constituting the PVA-based resin film (substantially a polarizing film) preferably contains a PVA-based resin modified by an acetyl acetyl group. With such a structure, a polarizing film having the desired puncture strength can be obtained. The blending amount of the PVA-based resin modified by the acetyl acetyl group is set to be 100% by weight of all PVA-based resins, preferably 5 to 20% by weight, and preferably 8 to 12% by weight. If the blending amount is within such a range, the puncture strength can fall within a more appropriate range.
偏光膜代表性上係可用二層以上之積層體製作。使用積層體製得之偏光膜的具體例上，可舉出使用樹脂基材與塗佈形成於該樹脂基材之PVA系樹脂層的積層體所製得之偏光膜。使用樹脂基材與塗佈形成於該樹脂基材之PVA系樹脂層的積層體所製得之偏光膜，舉例而言，係藉由下述步驟製得：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，以製得樹脂基材與PVA系樹脂層之積層體；及對該積層體進行延伸及染色而將PVA系樹脂層製成偏光膜。於本實施型態中，宜於樹脂基材的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。延伸代表性上係包含將積層體浸漬於硼酸水溶液中而進行延伸。進而，延伸宜更包含：於硼酸水溶液中延伸之前，將積層體以高溫(例如95℃以上)進行空中延伸。本發明之實施型態中，延伸總倍率例如為3.0倍~4.5倍，與一般相比顯著較小。即便為如此的延伸總倍率，亦可藉由結合添加鹵化物及乾燥收縮處理而得到具有可接受的光學特性之偏光膜。再者，本發明之實施型態中，空中輔助延伸之延伸倍率較硼酸水中延伸之延伸倍率大。藉由作成如此之構成，即便延伸總倍率小，亦可製得具有可接受的光學特性之偏光膜。此外，宜將積層體供於乾燥收縮處理，該乾燥收縮處理係藉由將積層體一邊朝長度方向輸送一邊加熱以使其寬度方向上收縮2%以上。於一實施型態中，偏光膜之製造方法包含對積層體依序實施空中輔助延伸處理、染色處理、水中延伸處理及乾燥收縮處理。藉由引入輔助延伸，即便在熱塑性樹脂上塗佈PVA的情況下，亦可提高PVA之結晶性，可達成高度的光學特性。又，同時藉由事先提高PVA之定向性，於後續之染色步驟及延伸步驟浸漬於水中時，可防止PVA之定向性降低及溶解等問題，可達成高度的光學特性。進一步而言，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，更可抑制聚乙烯醇分子定向之雜亂及定向性之降低。藉此可提升經由染色處理及水中延伸處理這等將積層體浸漬於液體中進行之處理步驟所製得之偏光膜的光學特性。藉由乾燥收縮處理使積層體於寬度方向上收縮，則可進一步提升光學特性。製得之樹脂基材/偏光膜之積層體可直接使用(即，可將樹脂基材作為偏光膜之保護層)，亦可自樹脂基材/偏光膜之積層體中剝離樹脂基材並於該剝離面積層因應目的之任意適當的保護層而使用。關於偏光膜之製造方法的詳細情形，之後會於C項敘述。The polarizing film is typically made of a laminate with two or more layers. Specific examples of the polarizing film obtained using the laminated system include a polarizing film prepared using a laminated body of a resin substrate and a PVA-based resin layer formed on the resin substrate by coating. The polarizing film produced by using a laminate of a resin substrate and a PVA resin layer formed on the resin substrate is, for example, produced by the following steps: Coating a PVA resin solution on the resin The substrate is dried to form a PVA-based resin layer on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; and the laminate is extended and dyed to form the PVA-based resin layer Polarizing film. In this embodiment, it is suitable to form a polyvinyl alcohol resin layer containing halide and polyvinyl alcohol resin on one side of the resin substrate. Stretching typically involves immersing the laminate in a boric acid aqueous solution to perform stretching. Furthermore, stretching preferably further includes stretching the laminate in the air at a high temperature (for example, 95°C or higher) before stretching in a boric acid aqueous solution. In the embodiment of the present invention, the total extension magnification is, for example, 3.0 to 4.5 times, which is significantly smaller than usual. Even with such a total extension magnification, a polarizing film with acceptable optical properties can be obtained by combining the addition of halide and drying shrinkage treatment. Furthermore, in the embodiment of the present invention, the extension ratio of the aerial auxiliary extension is larger than the extension ratio of the boric acid water extension. By making such a structure, even if the total stretching magnification is small, a polarizing film with acceptable optical properties can be obtained. In addition, it is preferable to subject the layered body to a drying shrinkage treatment in which the layered body is heated while being transported in the longitudinal direction to shrink it by 2% or more in the width direction. In one embodiment, the manufacturing method of the polarizing film includes sequentially performing aerial auxiliary stretching treatment, dyeing treatment, underwater stretching treatment and drying shrinkage treatment on the laminate. By introducing auxiliary extension, even when PVA is coated on the thermoplastic resin, the crystallinity of PVA can be improved and high optical properties can be achieved. In addition, by improving the orientation of PVA in advance, when immersing in water in the subsequent dyeing step and elongation step, the orientation of PVA can be prevented from decreasing and dissolving, and high optical properties can be achieved. Furthermore, when the PVA-based resin layer is immersed in a liquid, compared to the case where the PVA-based resin layer does not contain a halide, it is possible to suppress the disorder of the molecular orientation of the polyvinyl alcohol and the decrease of the orientation. This can improve the optical properties of the polarizing film produced by the process of immersing the laminate in a liquid, such as dyeing treatment and underwater stretching treatment. By drying and shrinking the laminate in the width direction, the optical properties can be further improved. The prepared resin substrate/polarizing film laminate can be used directly (that is, the resin substrate can be used as the protective layer of the polarizing film), or the resin substrate can be peeled from the resin substrate/polarizing film laminate and used The peeling area layer is used according to any suitable protective layer for the purpose. The details of the manufacturing method of the polarizing film will be described in item C later.
B.偏光板
圖1係本發明之一實施型態之偏光板的概略截面圖。偏光板100係具有偏光膜10、配置於偏光膜10之一側的第1保護層20及配置於偏光膜10之另一側的第2保護層30。偏光膜10為上述A項中說明之本發明的偏光膜。亦可省略第1保護層20及第2保護層30中之一者。且如上所述，第1保護層及第2保護層中之一者，可為用於製造上述偏光膜之樹脂基材。B. Polarizing plate
Fig. 1 is a schematic cross-sectional view of a polarizing plate of one embodiment of the present invention. The
第1及第2保護層係由可作為偏光膜之保護層使用之任意適當的薄膜形成。成為該薄膜主成分之材料之具體例上，可列舉：三醋酸纖維素(TAC)等之纖維素系樹脂及聚酯系、聚乙烯醇系、聚碳酸酯系、聚醯胺系、聚醯亞胺系、聚醚碸系、聚碸系、聚苯乙烯系、聚降莰烯系、聚烯烴系、(甲基)丙烯酸系、醋酸酯系等之透明樹脂。亦可列舉(甲基)丙烯酸系、胺甲酸乙酯系、(甲基)丙烯酸胺甲酸酯系、環氧系、聚矽氧系等之熱硬化型樹脂或紫外線硬化型樹脂等。其他還可舉例如矽氧烷系聚合物等玻璃質系聚合物。又，亦可使用於日本特開2001-343529號公報(WO01/37007)中所記載之聚合物薄膜。該薄膜之材料，舉例而言，可使用含有支鏈具取代或非取代之醯亞胺基之熱塑性樹脂、與支鏈具取代或非取代之苯基及腈基之熱塑性樹脂的樹脂組成物，例如可舉出具有由異丁烯與N-甲基馬來醯亞胺形成之交替共聚物及丙烯腈-苯乙烯共聚物的樹脂組成物。該聚合物薄膜例如可為上述樹脂組成物之擠製成形物。The first and second protective 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 used as the main component of the film include: cellulose resins such as cellulose triacetate (TAC) and polyester, polyvinyl alcohol, polycarbonate, polyamide, and polyamide Transparent resins of imine series, polyether series, polysulfide series, polystyrene series, polynorbornene series, polyolefin series, (meth)acrylic series, acetate series, etc. Other examples include (meth)acrylic, urethane, (meth)acrylate urethane, epoxy, silicone, and other thermosetting resins or ultraviolet curing resins. Other examples include glassy polymers such as silicone polymers. Moreover, it can also be used for the polymer film described in JP 2001-343529 A (WO01/37007). For the material of the film, for example, a resin composition containing a branched thermoplastic resin with substituted or unsubstituted imidinyl groups, and a branched thermoplastic resin with substituted or unsubstituted phenyl and nitrile groups can be used. For example, a resin composition having an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer can be mentioned. The polymer film may be, for example, an extruded product of the above-mentioned resin composition.
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之保護層(外側保護層)厚度，代表性上為300μm以下，且100μm以下為佳，5μm~80μm較佳，10μm~60μm更佳。另外，施有表面處理時，外側保護層厚度為包含表面處理層厚度之厚度。When the
將偏光板100應用於影像顯示裝置時配置於顯示面板側之保護層(內側保護層)厚度以5μm~200μm為佳，10μm~100μm較佳，10μm~60μm更佳。一實施型態中，內側保護層為具有任意適當之相位差值的相位差層。此時，相位差層之面內相位差Re(550)例如為110nm~150nm。「Re(550)」係於23℃下以波長550nm之光測得之面內相位差，可藉由式：Re＝(nx-ny)×d求算。於此，「nx」為面內折射率成為最大之方向(即慢軸方向)之折射率，「ny」為在面內與慢軸正交之方向(即快軸方向)之折射率，「nz」為厚度方向之折射率，「d」為層(薄膜)之厚度(nm)。When the
C.偏光膜之製造方法 本發明一實施型態之偏光膜之製造方法包含下述步驟：於長條狀熱塑性樹脂基材的單側，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)以製成積層體；及對積層體依序實施空中輔助延伸處理、染色處理、水中延伸處理及乾燥收縮處理，該乾燥收縮處理係藉由將積層體一邊朝長度方向輸送一邊加熱以使其寬度方向上收縮2%以上。PVA系樹脂層中之鹵化物含量宜相對於PVA系樹脂100重量份為5重量份~20重量份。乾燥收縮處理宜使用加熱輥進行處理，加熱輥之溫度宜為60℃~120℃。乾燥收縮處理所致之積層體寬度方向上之收縮率宜為2%以上。若以此製造方法，可製得上述A項中說明之偏光膜。特別是藉由製作包含有含鹵化物之PVA系樹脂層之積層體，並將上述積層體的延伸設為包含空中輔助延伸及水中延伸之多階段延伸，且以加熱輥加熱延伸後之積層體，可製得具有優秀光學特性(具代表性者為單體透射率及單位吸光度)之偏光膜。C. Manufacturing method of polarizing film The manufacturing method of a polarizing film of one embodiment of the present invention includes the following steps: forming a polyvinyl alcohol resin containing a halide and a polyvinyl alcohol resin (PVA resin) on one side of a long-shaped thermoplastic resin substrate Layer (PVA-based resin layer) to make a laminate; and sequentially perform aerial auxiliary stretching treatment, dyeing treatment, underwater stretching treatment, and drying shrinkage treatment on the laminate. The drying shrinkage treatment is performed by turning one side of the laminate in the length direction The conveying side is heated to shrink by more than 2% in the width direction. The halide content in the PVA-based resin layer is preferably 5 parts by weight to 20 parts by weight relative to 100 parts by weight of the PVA-based resin. The drying shrinkage should be treated with a heating roller, and the temperature of the heating roller should be 60℃~120℃. The shrinkage in the width direction of the laminate caused by the drying shrinkage treatment is preferably 2% or more. If this manufacturing method is used, the polarizing film described in item A above can be manufactured. In particular, by making a laminate containing a halogen-containing PVA-based resin layer, and extending the laminate as a multi-stage extension including aerial auxiliary extension and underwater extension, and heating the extended laminate with a heating roller , Can produce polarizing film with excellent optical properties (typically monomer transmittance and unit absorbance).
C-1.積層體之製作 熱塑性樹脂基材與PVA系樹脂層之積層體的製作方法，係可採用任意適當之方法。宜藉由於熱塑性樹脂基材之表面塗佈含有鹵化物與PVA系樹脂之塗佈液並加以乾燥，而於熱塑性樹脂基材上形成PVA系樹脂層。如上所述，PVA系樹脂層中之鹵化物含量宜相對於PVA系樹脂100重量份為5重量份~20重量份。C-1. Production of laminated body Any appropriate method can be adopted for the production method of the laminate of the thermoplastic resin substrate and the PVA-based resin layer. It is preferable to form a PVA resin layer on the thermoplastic resin substrate by coating the surface of the thermoplastic resin substrate with a coating solution containing halide and PVA resin and drying it. As described above, the halide content in the PVA-based resin layer is preferably 5 parts by weight to 20 parts by weight relative to 100 parts by weight of the PVA-based resin.
塗佈液之塗佈方法係可採用任意適當之方法。例如可列舉：輥塗法、旋塗法、線棒塗佈法、浸漬塗佈法、模塗法、簾幕式塗佈法、噴塗法、刮刀塗佈法(缺角輪塗佈法等)等。上述塗佈液之塗佈及乾燥溫度宜為50℃以上。Any appropriate method can be adopted for the coating method of the coating liquid. Examples include: roll coating method, spin coating method, wire bar coating method, dip coating method, die coating method, curtain coating method, spray coating method, knife coating method (cutting wheel coating method, etc.) Wait. The coating and drying temperature of the above-mentioned coating liquid is preferably 50°C or higher.
PVA系樹脂層之厚度以2μm~30μm為佳，2μm~20μm更佳。藉由將延伸前之PVA系樹脂層之厚度如所述般做成非常薄，且如後述將總延伸倍率設為較小，儘管定向函數非常小，亦可製得具有可接受的單體透射率及偏光度之偏光膜。The thickness of the PVA resin layer is preferably 2μm~30μm, more preferably 2μm~20μm. By making the thickness of the PVA-based resin layer before stretching very thin as described, and setting the total stretching magnification to be small as described later, even though the orientation function is very small, it can be produced with acceptable monomer transmission. Polarizing film with high efficiency and polarization degree.
形成PVA系樹脂層之前，可對熱塑性樹脂基材實施表面處理(例如電暈處理等)，亦可於熱塑性樹脂基材上形成易接著層。藉由進行如此之處理，可提升熱塑性樹脂基材與PVA系樹脂層之密著性。Before forming the PVA-based resin layer, the thermoplastic resin substrate may be subjected to surface treatment (for example, corona treatment, etc.), or an easily adhesive layer may be formed on the thermoplastic resin substrate. By performing such treatment, the adhesion between the thermoplastic resin substrate and the PVA-based resin layer can be improved.
C-1-1.熱塑性樹脂基材 熱塑性樹脂基材可採用任意適當之熱塑性樹脂薄膜。關於熱塑性樹脂基材的詳情，例如記載於日本特開2012-73580號公報。該公報之全部記載可援引作為本說明書之參考。C-1-1. Thermoplastic resin substrate Any suitable thermoplastic resin film can be used as the thermoplastic resin substrate. The details of the thermoplastic resin substrate are described in, for example, JP 2012-73580 A. All the records in the bulletin can be cited as a reference in this manual.
C-1-2.塗佈液 塗佈液係如上所述含有鹵化物及PVA系樹脂。上述塗佈液代表性上為上述鹵化物及上述PVA系樹脂溶解於溶劑之中的溶液。溶劑例如可列舉水、二甲亞碸、二甲基甲醯胺、二甲基乙醯胺、N-甲基吡咯啶酮、各種二元醇類、三羥甲丙烷等多元醇類及伸乙二胺、二伸乙三胺等胺類。可將其等單獨或是組合二種以上來使用。其等之中又以水為佳。溶液之PVA系樹脂濃度宜相對於溶劑100重量份為3重量份~20重量份。若為如此之樹脂濃度，可形成密著於熱塑性樹脂基材之均勻塗佈膜。塗佈液中之鹵化物含量宜相對於PVA系樹脂之100重量份為5重量份~20重量份。C-1-2. Coating liquid The coating liquid contains halide and PVA-based resin as described above. The coating liquid is typically a solution in which the halide and the PVA-based resin are dissolved in a solvent. Solvents include, for example, water, dimethyl sulfide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, trimethylolpropane and other polyols and ethylene glycol. Amines such as diamine and diethylenetriamine. These can be used alone or in combination of two or more kinds. Among them, water is better. The concentration of the PVA-based resin in the solution is preferably 3 to 20 parts by weight relative to 100 parts by weight of the solvent. With such a resin concentration, a uniform coating film that adheres to the thermoplastic resin substrate can be formed. The halide content in the coating solution is preferably 5 to 20 parts by weight relative to 100 parts by weight of the PVA-based resin.
塗佈液中亦可摻合添加劑。添加劑例如可列舉塑化劑及界面活性劑等。塑化劑可舉例如乙二醇及丙三醇等之多元醇。界面活性劑可舉非離子界面活性劑為例。此等係可為了使所得PVA系樹脂層之均勻性、染色性及延伸性進一步提高之目的而使用。Additives may also be blended in the coating liquid. Examples of additives include plasticizers and surfactants. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol and glycerol. Surfactants can be exemplified by nonionic surfactants. These systems can be used for the purpose of further improving the uniformity, dyeability, and extensibility of the obtained PVA-based resin layer.
上述PVA系樹脂可採用任意適當之樹脂。例可列舉聚乙烯醇及乙烯-乙烯醇共聚物。聚乙烯醇可藉由皂化聚乙酸乙烯酯而得到。乙烯-乙烯醇共聚物可藉由皂化乙烯-乙酸乙烯酯共聚物而得到。PVA系樹脂之皂化度通常為85莫耳%~100莫耳%，較佳為95.0莫耳%~99.95莫耳%，更佳為99.0莫耳%~99.93莫耳%。皂化度係可遵循JIS K 6726-1994求算。藉由使用如此皂化度之PVA系樹脂可得到耐久性優秀之偏光膜。若皂化度過高，可能會有膠化的風險。如上所述，PVA系樹脂宜含有經乙醯乙醯基改質之PVA系樹脂。Any appropriate resin can be used for the above-mentioned PVA-based resin. Examples include polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer can be obtained by saponifying an ethylene-vinyl acetate copolymer. The degree of saponification of the PVA-based resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, and more preferably 99.0 mol% to 99.93 mol%. The degree of saponification can be calculated in accordance with JIS K 6726-1994. By using the PVA-based resin with such a degree of saponification, a polarizing film with excellent durability can be obtained. If the saponification is too high, there may be a risk of gelation. As mentioned above, the PVA-based resin preferably contains a PVA-based resin modified by an acetyl acetyl group.
PVA系樹脂之平均聚合度可因應其目的適當選擇。平均聚合度通常為1000~10000，較佳為1200~4500，更佳為1500~4300。另外，平均聚合度可遵循JIS K 6726-1994求算。The average degree of polymerization of the PVA-based resin can be appropriately selected according to its 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 calculated in accordance with JIS K 6726-1994.
上記鹵化物可採用任意適當之鹵化物。例如可列舉碘化物及氯化鈉。碘化物例如可列舉碘化鉀、碘化納及碘化鋰。其等之中，又以碘化鉀為佳。Any appropriate halide can be used as the above-mentioned halide. Examples include iodide and sodium chloride. Examples of the iodide include potassium iodide, sodium iodide, and lithium iodide. Among them, potassium iodide is preferred.
塗佈液中之鹵化物量宜相對於PVA系樹脂100重量份為5重量份~20重量份，且相對於PVA系樹脂100重量份為10重量份~15重量份較佳。若相對於PVA系樹脂100重量份之鹵化物量超過20重量份，會有鹵化物滲出使最終所得之偏光膜出現白濁的情況發生。The amount of halide in the coating solution is preferably 5 parts by weight to 20 parts by weight relative to 100 parts by weight of the PVA resin, and preferably 10 parts by weight to 15 parts by weight relative to 100 parts by weight of the PVA resin. If the amount of the halide relative to 100 parts by weight of the PVA-based resin exceeds 20 parts by weight, the halide may bleed out and the resulting polarizing film may appear cloudy.
一般而言，藉由延伸PVA系樹脂層，會提高PVA系樹脂中聚乙烯醇分子的定向性，但將延伸後之PVA系樹脂層浸漬於含水液體時，會有聚乙烯醇分子定向雜亂、定向性降低的情況發生。特別是將熱塑性樹脂與PVA系樹脂層之積層體於硼酸水中延伸時，在為了安定熱塑性樹脂之延伸而於較高溫度下將上述積層體於硼酸水中延伸的情況下，上述定向度降低之傾向顯著。舉例而言，PVA薄膜單體於硼酸水中之延伸一般在60℃下進行，相對於此，A-PET(熱塑性樹脂基材)與PVA系樹脂層之積層體之延伸則在溫度約70℃這樣之高溫下進行，於此情況下，延伸初期PVA之定向性可能會在藉由水中延伸而提升之前的階段降低。對此，藉由製作含鹵化物之PVA系樹脂層與熱塑性樹脂基材之積層體，並且在積層體於硼酸水中延伸之前於空氣中進行高溫延伸(輔助延伸)，可促進輔助延伸後積層體之PVA系樹脂層中PVA系樹脂的結晶化。其結果是將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，更可抑制聚乙烯醇分子定向之雜亂及定向性之降低。藉此可提升經由染色處理及水中延伸處理這等將積層體浸漬於液體中進行之處理步驟所製得之偏光膜的光學特性。Generally speaking, by extending the PVA-based resin layer, the orientation of the polyvinyl alcohol molecules in the PVA-based resin will be improved. However, when the stretched PVA-based resin layer is immersed in an aqueous liquid, the orientation of the polyvinyl alcohol molecules will be disordered, Reduced orientation occurs. Especially when a laminate of thermoplastic resin and PVA-based resin layers is stretched in boric acid water, when the laminate is stretched in boric acid water at a relatively high temperature in order to stabilize the elongation of the thermoplastic resin, the degree of orientation tends to decrease Significant. For example, the stretching of the PVA film monomer in boric acid water is generally performed at 60°C. In contrast, the stretching of the laminate of A-PET (thermoplastic resin substrate) and PVA-based resin layer is at a temperature of about 70°C. In this case, the orientation of the PVA at the initial stage of extension may be reduced in the stage before it is improved by extension in water. In this regard, by making a laminate of a halide-containing PVA-based resin layer and a thermoplastic resin base material, and performing high-temperature extension in the air before the laminate is extended in boric acid water (assisted extension), the post-assisted extension of the laminate can be promoted The crystallization of PVA resin in the PVA resin layer. As a result, when the PVA-based resin layer is immersed in a liquid, compared to the case where the PVA-based resin layer does not contain a halide, it is possible to suppress the disorder of the molecular orientation of the polyvinyl alcohol and the decrease of the orientation. This can improve the optical properties of the polarizing film produced by the process of immersing the laminate in a liquid, such as dyeing treatment and underwater stretching treatment.
C-2.空中輔助延伸處理 特別是為了得到高度的光學特性，可選擇結合乾式延伸(輔助延伸)與硼酸水中延伸之2段延伸方法。藉由如2段延伸般導入輔助延伸，可同時抑制熱塑性樹脂基材之結晶化並進行延伸。更進一步而言，於熱塑性樹脂基材上塗佈PVA系樹脂時，為了抑制熱塑性樹脂基材之玻璃轉化溫度的影響，相較通常在金屬筒上塗佈PVA系樹脂的情況需要更降低塗佈溫度，其結果可能會發生PVA系樹脂之結晶化相對變低而無法得到足夠的光學特性的問題。對此，藉由引入輔助延伸，即便在熱塑性樹脂上塗佈PVA系樹脂的情況下，亦可提高PVA系樹脂之結晶性，而可達成高度的光學特性。又，同時藉由事先提高PVA系樹脂之定向性，於後續之染色步驟及延伸步驟將其浸漬於水中時，可防止PVA系樹脂之定向性降低及溶解等問題，而可達成高度的光學特性。C-2. Air auxiliary extension processing Especially in order to obtain a high degree of optical properties, a two-stage extension method combining dry extension (auxiliary extension) and extension in boric acid water can be selected. By introducing auxiliary stretching like two-stage stretching, it is possible to simultaneously suppress the crystallization of the thermoplastic resin base material and perform stretching. Furthermore, when coating PVA-based resin on a thermoplastic resin substrate, in order to suppress the influence of the glass transition temperature of the thermoplastic resin substrate, it is necessary to reduce the amount of coating compared to the usual case of coating PVA-based resin on a metal cylinder. As a result of the temperature, the crystallization of the PVA-based resin may be relatively low, and sufficient optical characteristics may not be obtained. In this regard, by introducing auxiliary extension, even when a PVA-based resin is coated on a thermoplastic resin, the crystallinity of the PVA-based resin can be improved, and high optical properties can be achieved. At the same time, by improving the orientation of the PVA-based resin in advance, when it is immersed in water in the subsequent dyeing and stretching steps, the orientation of the PVA-based resin can be prevented from decreasing and dissolving, and high optical properties can be achieved. .
空中輔助延伸之延伸方法可為固定端延伸(例如，使用拉幅延伸機拉伸之方法)，亦可為自由端延伸(例如，使積層體通過圓周速度相異之輥間進行單軸延伸之方法)，但為了得到高度的光學特性，可積極採用自由端延伸。於一實施型態中，空中延伸處理包含加熱輥延伸步驟，係將上述積層體朝其長邊方向輸送的同時，藉由加熱輥間之圓周速度差進行延伸。空中延伸處理代表性上係包含區域延伸步驟與加熱輥延伸步驟。且，進行區域延伸步驟與加熱輥延伸步驟之順序並無限定，可先進行區域延伸步驟，亦可先進行加熱輥延伸步驟。亦可省略區域延伸步驟。於一實施型態中，可依區域延伸步驟及加熱輥延伸步驟之順序進行。又，於另一實施型態中，係於拉幅延伸機藉由把持住薄膜端部，將拉幅機間之距離沿流動方向擴展以進行延伸(拉幅機間之距離的擴展會成為延伸倍率)。此時，寬度方向(相對於流動方向為垂直方向)之拉幅機距離係可設定為任意靠近。較佳可設定為相對於流動方向之延伸倍率利用自由端延伸而靠近。自由端延伸時，係以寬度方向之收縮率＝(1/延伸倍率)1/2 來計算。The extension method of aerial auxiliary extension can be fixed end extension (for example, the method of stretching using a tenter stretching machine) or free end extension (for example, uniaxial extension of the laminated body through rollers with different peripheral speeds) Method), but in order to obtain a high degree of optical characteristics, free end extension can be actively used. In one embodiment, the in-flight stretching process includes a heating roller stretching step, in which the laminate is conveyed in the longitudinal direction and stretched by the circumferential speed difference between the heating rollers. The aerial stretching process typically includes a region stretching step and a heating roller stretching step. Moreover, the order of performing the area extension step and the heating roller extension step is not limited, and the area extension step may be performed first, or the heating roller extension step may be performed first. The region extension step can also be omitted. In one embodiment, it can be performed in the order of the area extension step and the heating roller extension step. Also, in another embodiment, the stenter stretcher holds the end of the film and expands the distance between the stenters along the flow direction for extension (the extension of the distance between the stenters becomes the extension Magnification). At this time, the stenter distance in the width direction (vertical to the flow direction) can be set arbitrarily close. Preferably, it can be set so that the extension ratio relative to the flow direction is approached by extension of the free end. When the free end is stretched, it is calculated as the shrinkage rate in the width direction=(1/stretching ratio) 1/2 .
空中輔助延伸可以一階段進行，亦可以多階段進行。以多階段進行時，延伸倍率為各階段延伸倍率之積。空中輔助延伸之延伸方向，宜與水中延伸之延伸方向幾乎相同。Aerial auxiliary extension can be carried out in one stage or in multiple stages. When it is performed in multiple stages, the stretching ratio is the product of the stretching ratios of each stage. The extension direction of the aerial auxiliary extension should be almost the same as the extension direction of the underwater extension.
空中輔助延伸之延伸倍率以1.0倍~4.0倍為佳、1.5倍~3.5倍較佳、2.0倍~3.0倍更佳。若空中輔助延伸之延伸倍率為如此之範圍，可將結合水中延伸時之延伸總倍率設定於期望之範圍，可實現期望之定向函數。其結果可得到沿吸收軸方向之破斷受到抑制之偏光膜。此外，如上所述，空中輔助延伸之延伸倍率較硼酸水中延伸之延伸倍率大。藉由設為如此之構成，即便延伸之總倍率小，亦可得到具有可接受的光學特性之偏光膜。The extension ratio of aerial auxiliary extension is preferably 1.0 to 4.0 times, 1.5 to 3.5 times, and 2.0 to 3.0 times better. If the stretch magnification of the aerial auxiliary stretch is such a range, the total stretch magnification when combined with underwater stretch can be set to the desired range, and the desired orientation function can be realized. As a result, it is possible to obtain a polarizing film whose breakage along the absorption axis is suppressed. In addition, as mentioned above, the stretching ratio of aerial auxiliary stretching is larger than that of boric acid water stretching. With such a configuration, even if the total extension magnification is small, a polarizing film with acceptable optical properties can be obtained.
空中輔助延伸之延伸溫度可對應熱塑性樹脂基材之形成材料、延伸方式等，設定為任意適當之值。延伸溫度以熱塑性樹脂基材之玻璃轉化溫度(Tg)以上為佳、熱塑性樹脂基材之玻璃轉化溫度(Tg)＋10℃以上較佳、Tg＋15℃以上特佳。另一方面，延伸溫度之上限以170℃為佳。藉由以如此之溫度進行延伸，可抑制PVA系樹脂之結晶化急速進行，而可抑制該結晶化造成之不佳狀況(例如，妨礙藉由延伸所致之PVA系樹脂層之定向)。The stretching temperature of the aerial auxiliary stretching can be set to any appropriate value corresponding to the forming material and stretching method of the thermoplastic resin substrate. The elongation temperature is preferably above the glass transition temperature (Tg) of the thermoplastic resin substrate, preferably above the glass transition temperature (Tg) of the thermoplastic resin substrate + 10°C, and particularly preferably above the Tg + 15°C. On the other hand, the upper limit of the extension temperature is preferably 170°C. By stretching at such a temperature, the rapid progress of crystallization of the PVA-based resin can be suppressed, and disadvantages caused by the crystallization (for example, hindering the orientation of the PVA-based resin layer due to the stretching) can be suppressed.
C-3.不溶化處理、染色處理及交聯處理 因應需求，於空中輔助延伸處理之後且水中延伸處理及染色處理之前，實施不溶化處理。上述不溶化處理代表性上係藉由將PVA系樹脂層浸漬於硼酸水溶液中來進行。上述染色處理代表性上係藉由將PVA系樹脂層以二色性物質(具代表性者為碘)染色來進行。因應需求，於染色處理之後且水中延伸處理之前，實施交聯處理。上述交聯處理代表性上係藉由將PVA系樹脂層浸漬於硼酸水溶液中來進行。關於不溶化處理、染色處理及交聯處理之詳細情形，例如記載於日本特開2012-73580號公報(上述)中。C-3. Insoluble treatment, dyeing treatment and cross-linking treatment In response to demand, insolubilization treatment is performed after the aerial auxiliary extension treatment and before the underwater extension treatment and dyeing treatment. The above-mentioned insolubilization treatment is typically performed by immersing the PVA-based resin layer in a boric acid aqueous solution. The above-mentioned dyeing treatment is typically performed by dyeing the PVA-based resin layer with a dichroic substance (typically, iodine). According to demand, cross-linking treatment is implemented after dyeing treatment and before water extension treatment. The crosslinking treatment is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. The details of the insolubilization treatment, the dyeing treatment, and the cross-linking treatment are described in, for example, JP 2012-73580 A (above).
C-4.水中延伸處理 水中延伸處理係將積層體浸漬於延伸浴中進行。藉由水中延伸處理，可於較上述熱塑性樹脂基材及PVA系樹脂層之玻璃轉化溫度(代表性上約為80℃)低之溫度下進行延伸，可於抑制PVA系樹脂層之結晶化的同時進行延伸。其結果可製造出具有優秀光學特性之偏光膜。C-4. Water extension treatment The underwater stretching treatment is performed by immersing the laminate in a stretching bath. The stretching in water can be stretched at a temperature lower than the glass transition temperature (typically about 80°C) of the thermoplastic resin substrate and PVA-based resin layer, which can inhibit the crystallization of the PVA-based resin layer. Simultaneous extension. As a result, a polarizing film with excellent optical properties can be manufactured.
積層體之延伸方法係可採用任意適當之方法。具體而言，可為固定端延伸，亦可為自由端延伸(例如，使積層體通過圓周速度相異之輥間進行單軸延伸之方法)。較佳為選擇自由端延伸。積層體之延伸可以一階段進行，亦可以多階段進行。以多階段進行時，延伸倍率為各階段延伸倍率之積。Any appropriate method can be adopted for the extension method of the laminate. Specifically, it may be a fixed-end extension or a free-end extension (for example, a method of uniaxially extending a laminate through rollers with different peripheral speeds). It is preferable to choose free end extension. The extension of the laminated body can be carried out in one stage or in multiple stages. When it is performed in multiple stages, the stretching ratio is the product of the stretching ratios of each stage.
水中延伸宜將積層體浸漬於硼酸水溶液中進行(硼酸水中延伸)。藉由使用硼酸水溶液作為延伸浴，可賦予PVA系樹脂層可承受延伸時施加之張力的剛性與不溶解於水的耐水性。具體而言，硼酸於水溶液中會生成四羥基硼酸根陰離子而可藉由氫鍵與PVA系樹脂進行交聯。其結果，會賦予PVA系樹脂層剛性及耐水性，可良好地進行延伸，並可製造出具有優秀光學特性之偏光膜。Stretching in water is preferably carried out by immersing the laminate in an aqueous boric acid solution (extending in boric acid in water). By using an aqueous solution of boric acid as a stretching bath, the PVA-based resin layer can be given rigidity that can withstand the tension applied during stretching and water resistance that is insoluble in water. Specifically, boric acid generates tetrahydroxyborate anions in an aqueous solution and can be crosslinked with PVA-based resins through hydrogen bonds. As a result, rigidity and water resistance are imparted to the PVA-based resin layer, can be stretched well, and a polarizing film with excellent optical properties can be manufactured.
上述硼酸水溶液宜藉由將硼酸及/或硼酸鹽溶解於作為溶劑之水中以製得。硼酸濃度相對於水100重量份以1重量份~10重量份為佳、2.5重量份~6重量份較佳、3重量份~5重量份特佳。藉由將硼酸濃度設為1重量份以上，可有效抑制PVA系樹脂層之溶解，並可製造出更高特性之偏光膜。且，亦可使用除硼酸或硼酸鹽以外還在溶劑中溶解硼砂等硼化合物、乙二醛、戊二醛等所得之水溶液。The above-mentioned aqueous solution of boric acid is preferably prepared by dissolving boric acid and/or borate in water as a solvent. The concentration of boric acid relative to 100 parts by weight of water is preferably 1 part by weight to 10 parts by weight, preferably 2.5 parts by weight to 6 parts by weight, and particularly preferably 3 parts by weight to 5 parts by weight. By setting the concentration of boric acid to 1 part by weight or more, the dissolution of the PVA-based resin layer can be effectively suppressed, and a polarizing film with higher characteristics can be manufactured. Furthermore, in addition to boric acid or borate, an aqueous solution obtained by dissolving boron compounds such as borax, glyoxal, glutaraldehyde, etc. in a solvent can also be used.
宜於上述延伸浴(硼酸水溶液)中摻合碘化物。藉由摻合碘化物，可抑制吸附於PVA系樹脂層之碘的溶析。碘化物之具體例係如上所述。碘化物之濃度相對於水100重量份以0.05重量份~15重量份為佳、0.5重量份~8重量份較佳。It is suitable to blend iodide in the above-mentioned extension bath (aqueous boric acid solution). By blending iodide, the elution of iodine adsorbed on 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, preferably 0.5 to 8 parts by weight, relative to 100 parts by weight of water.
延伸溫度(延伸浴之溶液溫度)係以40℃~85℃為佳、60℃~75℃較佳。若為如此之溫度，可於抑制PVA系樹脂層之溶解的同時，高倍率地進行延伸。具體而言，如上所述，在與PVA系樹脂層之形成的關係上，熱塑性樹脂基材之玻璃轉化溫度(Tg)以60℃以上為佳。此情況下，延伸溫度低於40℃以下時，即便考慮了水中熱塑性樹脂基材之塑化，亦有無法良好進行延伸的風險。另一方面，隨著延伸浴之溫度越為高溫，PVA系樹脂層之溶解性會變高，有無法得到優秀光學特性的風險。積層體於延伸浴中之浸漬時間以15秒~5分為佳。The extension temperature (solution temperature of the extension bath) is preferably 40°C~85°C, preferably 60°C~75°C. If it is such a temperature, the PVA-based resin layer can be stretched at a high rate while suppressing the dissolution of the PVA-based resin layer. Specifically, as described above, in relation to the formation of the PVA-based resin layer, the glass transition temperature (Tg) of the thermoplastic resin substrate is preferably 60°C or higher. In this case, when the stretching temperature is lower than 40°C, even if the plasticization of the thermoplastic resin substrate in water is considered, there is a risk that stretching cannot be performed well. On the other hand, as the temperature of the stretching bath becomes higher, the solubility of the PVA-based resin layer becomes higher, and there is a risk that excellent optical properties cannot be obtained. The immersion time of the laminate in the extension bath is preferably 15 seconds to 5 minutes.
水中延伸之延伸倍率以1.0倍~3.0倍為佳、1.0倍~2.0倍較佳、1.0倍~1.5倍更佳。若水中延伸之延伸倍率為如此之範圍，便可將延伸之總倍率設於所期望之範圍，並可實現所期望之定向函數。其結果，可得到沿吸收軸方向之破斷受到抑制之偏光膜。延伸之總倍率(結合空中輔助延伸與水中延伸時之延伸倍率的合計)係如上所述，相對於積層體之原長例如為3.0倍~4.5倍、較佳為3.0倍~4.0倍、更佳為3.0倍~3.5倍。藉由於塗佈液中添加鹵化物、調整空中輔助延伸及水中延伸之延伸倍率以及適當結合乾燥收縮處理，即便為如此之延伸總倍率亦可得到具有可接受的光學特性之偏光膜。The extension magnification of water extension is preferably 1.0 to 3.0 times, 1.0 to 2.0 times is better, and 1.0 to 1.5 times is even better. If the stretching magnification of underwater stretching is in such a range, the total stretching magnification can be set in the desired range and the desired orientation function can be achieved. As a result, it is possible to obtain a polarizing film in which breakage in the direction of the absorption axis is suppressed. The total extension magnification (combining the sum of the extension magnification in the air-assisted extension and the underwater extension) is as described above, relative to the original length of the laminate, for example, 3.0 times to 4.5 times, preferably 3.0 times to 4.0 times, more preferably It is 3.0 to 3.5 times. By adding halide to the coating solution, adjusting the stretching magnification of air-assisted stretching and water stretching, and appropriately combining the drying shrinkage treatment, even such a total stretching magnification can obtain a polarizing film with acceptable optical properties.
C-5.乾燥收縮處理 上述乾燥收縮處理可藉由將全部區域加熱以進行之區域加熱進行，亦可藉由加熱輸送輥(使用所謂的加熱輥)進行(加熱輥乾燥方式)。較佳為兩者皆使用。藉由使用加熱輥使其乾燥，可有效率抑制積層體之加熱卷曲，而可製造出外觀優秀之偏光膜。具體而言，藉由使積層體於順沿著加熱輥的狀態下進行乾燥，可有效率地促進上記熱塑性樹脂基材之結晶化並增加結晶化度，即便在較低的乾燥溫度下，亦可良好地增加熱塑性樹脂基材的結晶化度。其結果是熱塑性樹脂基材其剛性增加而成為可承受乾燥所致的PVA系樹脂層收縮之狀態，得以抑制卷曲。又藉由使用加熱輥，因可在將積層體維持於平坦狀態的同時進行乾燥，故不只可抑制卷曲亦可抑制皺褶之發生。此時，藉由乾燥收縮處理使積層體於寬度方向上收縮而可提升光學特性。此為可有效提升PVA及PVA/碘錯合物之定向性之故。乾燥收縮處理所致之積層體寬度方向之收縮率以1%~10%為佳、2%~8%較佳、4%~6%特佳。C-5. Drying shrinkage treatment The above-mentioned drying and shrinking treatment may be performed by area heating in which the entire area is heated, or may be performed by heating a conveying roller (using a so-called heating roller) (heating roller drying method). Preferably, both are used. By using a heating roller to dry it, heating and curling of the laminate can be effectively suppressed, and a polarizing film with excellent appearance can be manufactured. Specifically, by drying the laminate in a state along the heating roller, the crystallization of the above-mentioned thermoplastic resin substrate can be efficiently promoted and the degree of crystallinity can be increased, even at a lower drying temperature. It can well increase the crystallinity of the thermoplastic resin substrate. As a result, the rigidity of the thermoplastic resin base material is increased to be able to withstand the shrinkage of the PVA-based resin layer due to drying, and curling can be suppressed. In addition, by using a heating roller, the laminate can be dried while maintaining a flat state, so that not only curling but also wrinkles can be suppressed. At this time, the layered body is shrunk in the width direction by the drying shrinkage treatment to improve the optical properties. This is because it can effectively improve the orientation of PVA and PVA/iodine complexes. The shrinkage in the width direction of the laminate caused by the drying shrinkage treatment is preferably 1%~10%, 2%~8% is better, and 4%~6% is particularly good.
圖2係顯示乾燥收縮處理之一例的概略圖。乾燥收縮處理中，係藉由已加熱至預定溫度之輸送輥R1~R6與導引輥G1~G4來輸送積層體200同時使其乾燥。圖示例中，輸送輥R1~R6係配置成可交替對PVA樹脂層之面與熱塑性樹脂基材之面進行連續加熱，但亦可例如將輸送輥R1~R6配置成只對積層體200之一面(例如熱塑性樹脂基材面)進行連續加熱。Fig. 2 is a schematic diagram showing an example of drying shrinkage treatment. In the drying and shrinking process, the
藉由調整輸送輥之加熱溫度(加熱輥之溫度)、加熱輥之數量、與加熱輥之接觸時間等，可以控制乾燥條件。加熱輥之溫度以60℃~120℃為佳、65℃~100℃更佳、70℃~80℃特佳。可良好地增加熱塑性樹脂之結晶化度而良好地抑制卷曲，並且可製造出耐久性極為優秀之光學積層體。且，加熱輥之溫度可藉由接觸式溫度計量測。圖示例中設有6個輸送輥，但只要輸送輥為複數個即無特別限制。輸送輥通常設置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)以1秒~300秒為佳、1~20秒較佳、1~10秒更佳。By adjusting the heating temperature of the conveying roller (temperature of the heating roller), the number of heating rollers, the contact time with the heating roller, etc., the drying conditions can be controlled. The temperature of the heating roller is preferably 60°C~120°C, 65°C~100°C is more preferred, and 70°C~80°C is especially preferred. The degree of crystallinity of the thermoplastic resin can be increased well, curling can be well suppressed, and an optical laminate with excellent durability can be manufactured. Moreover, the temperature of the heating roller can be measured by contact temperature measurement. In the example shown in the figure, there are 6 conveying rollers, but there is no particular limitation as long as there are plural conveying rollers. The conveying rollers are usually provided with 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, and more preferably 1 to 10 seconds.
加熱輥可設置於加熱爐(例如烘箱)內，亦可設置於一般的生產線(室溫環境下)。較佳為設置於具備送風機構之加熱爐內。藉由併用以加熱輥進行之乾燥與熱風乾燥，可抑制加熱輥間之急遽的溫度變化，而可輕易控制寬度方向之收縮。熱風乾燥之溫度較佳為30℃~100℃。又，熱風乾燥時間較佳為1秒~300秒。熱風之風速較佳為10m/s~30m/s左右。且，該風速為加熱爐內之風速，可藉由迷你扇葉型數位風速計量測。The heating roller can be installed in a heating furnace (such as an oven) or in a general production line (under room temperature). It is preferably installed in a heating furnace equipped with an air blowing mechanism. By combining drying with heating rollers and hot-air drying, rapid temperature changes between heating rollers can be suppressed, and the shrinkage in the width direction can be easily controlled. The temperature of hot air drying is preferably 30°C to 100°C. In addition, the hot air drying time is preferably 1 second to 300 seconds. The wind speed of the hot air is preferably about 10m/s~30m/s. Moreover, the wind speed is the wind speed in the heating furnace, which can be measured by the mini fan blade type digital wind speed measurement.
C-6.其他處理 宜在水中延伸處理之後且乾燥收縮處理之前實施洗淨處理。上述洗淨處理代表性上為藉由將PVA系樹脂層浸漬於碘化鉀水溶液中來進行。C-6. Other processing It is advisable to carry out the washing treatment after the water extension treatment and before the drying shrinkage treatment. The above-mentioned washing treatment is typically performed by immersing the PVA-based resin layer in a potassium iodide aqueous solution.
實施例 以下，根據實施例對本發明進行具體說明，但本發明並不限定於此等實施例。各特性之測量方法如以下所述。另外，除非特地註明，否則實施例及比較例中之「份」及「%」為重量基準。 (1)厚度 使用干涉式膜厚計(大塚電子公司製，製品名「MCPD-3000」)測定。用以算出厚度之計算波長範圍為400nm~500nm、折射率為1.53。 (2)定向函數 關於實施例及比較例中所得之偏光膜，使用傅立葉轉換紅外光譜儀(FT-IR)(Perkin Elmer公司製，商品名：「Frontier」)，以經偏光之紅外光作為測定光，進行偏光膜表面的衰減全反射分光(ATR：attenuated total reflection)測定。使偏光膜密著之微晶係使用鍺，測定光之入射角設為45°入射。定向函數之計算按以下順序進行。將入射之經偏光之紅外光(測定光)作為平行於使鍺結晶樣品密著之面振動的偏光(s偏光)，並在相對於測定光之偏光方向將偏光膜之延伸方向配置為垂直(⊥)及平行(//)的狀態下測定各自的吸收光譜。由所得之吸收光譜，算出以(3330cm-1 強度)作為參考之(2941cm-1 強度)I。I⊥ 係相對於測定光之偏光方向將偏光膜之延伸方向配置為垂直(⊥)時，由所得之吸收光譜獲得之(2941cm-1 強度)/(3330cm-1 強度)。又，I// 係相對於測定光之偏光方向將偏光膜之延伸方向配置為平行(//)時，由所得之吸收光譜獲得之(2941cm-1 強度)/(3330cm-1 強度)。於此，(2941cm-1 強度)係以吸收光譜吸光度最低處之2770cm-1 與2990cm-1 作為基準線時之2941cm-1 之吸光度，(3330cm-1 強度)係以2990cm-1 與3650cm-1 作為基準線時之3330cm-1 之吸光度。使用所得之I⊥ 及I// ，依照式1算出定向函數f。且，f＝1時成為完全定向，f＝0時成為隨機。此外，2941cm-1 處之尖峰被認為是因偏光膜中PVA的主鏈(-CH2 -)振動而造成的吸收。又，3330cm-1 處之尖峰被認為是因PVA的羥基振動而造成的吸收。 (式1) f＝(3＜cos2θ＞-1)/2 ＝(1-D)/［c(2D＋1)］ 惟，c＝(3cos2 β-1)/2， 如上所述使用2941cm-1 時，β＝90°⇒f＝-2×(1-D)/(2D＋1)。 θ：分子鏈相對於延伸方向之角度 β：躍遷偶極距相對於分子鏈軸之角度 D＝(I⊥ )/(I// ) I⊥ ：測定光之偏光方向與偏光膜之延伸方向為垂直時的吸收強度 I// ：測定光之偏光方向與偏光膜之延伸方向為平行時的吸收強度 (3)單體透射率及偏光度 由實施例及比較例中使用之偏光膜/熱塑性樹脂基材之積層體剝離偏光膜，並將針對該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」)測得之單體透射率Ts、平行透射率Tp、直交透射率Tc各自作為偏光膜之Ts、Tp及Tc。該等Ts、Tp及Tc為藉由JIS Z8701之2度視野(C光源)測定並進行視感度校正後之Y值。 由所得之Tp及Tc，藉由下式求算偏光度P。 偏光度P(%)＝｛(Tp-Tc)/(Tp＋Tc)｝1/2 ×100 且，分光光度計以大塚電子公司製「LPF-200」等亦可進行同等之測定，已確認使用任一分光光度計皆可得到同等之測定結果。 (4)破斷強度 由實施例及比較例中使用之偏光膜/熱塑性樹脂基材之積層體剝離偏光膜，並將該偏光膜裝載於已安裝穿刺針之壓縮試驗機(Kato-tech公司製，製品名「NDG5」穿刺針貫通力測定型號)，於室溫(23℃±3℃)環境下，以穿刺速度0.33cm/秒進行穿刺，將偏光膜破裂時之強度作為破斷強度(穿刺強度)。評估值為測定10個樣品片之破斷強度，並使用其平均值。且，穿刺針使用前端徑1mmφ且0.5R者。對於測定之偏光膜，以具有直徑約11mm之圓形開口部之夾具由偏光膜之兩面夾住予以固定，將穿刺針穿刺於開口部之中央來進行試驗。以每單位厚度之破斷強度作為破裂難易度之指標，並按以下之基準評估。 ○：破斷強度超過30gf/μm ×：破斷強度30gf/μm以下Examples Hereinafter, the present invention will be specifically explained based on examples, but the present invention is not limited to these examples. The measurement methods of each characteristic are as follows. In addition, unless otherwise noted, "parts" and "%" in the examples and comparative examples are based on weight. (1) The thickness is measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name "MCPD-3000"). The wavelength range used to calculate the thickness is 400nm~500nm, and the refractive index is 1.53. (2) Orientation function For the polarizing films obtained in the examples and comparative examples, a Fourier transform infrared spectrometer (FT-IR) (manufactured by Perkin Elmer, trade name: "Frontier") was used, and polarized infrared light was used as the measurement light , Perform attenuated total reflection spectroscopy (ATR: attenuated total reflection) measurement on the surface of the polarizing film. The microcrystalline system to which the polarizing film is adhered is germanium, and the incident angle of the measured light is set to be incident at 45°. The calculation of the orientation function is performed in the following order. The incident polarized infrared light (measurement light) is regarded as polarized light (s-polarized light) that vibrates parallel to the surface where the germanium crystal sample is adhered, and the extension direction of the polarizing film is arranged perpendicular to the polarization direction of the measurement light ( ⊥) and parallel (//) measurement of the respective absorption spectra. From the obtained absorption spectrum, calculate (2941 cm -1 intensity) I with (3330 cm -1 intensity) as a reference. I ⊥ is the (2941cm -1 intensity)/(3330cm -1 intensity) obtained from the absorption spectrum when the extension direction of the polarizing film is arranged perpendicular to the polarization direction of the measured light (⊥). In addition, I // is the (2941cm -1 intensity)/(3330cm -1 intensity) obtained from the obtained absorption spectrum when the extension direction of the polarizing film is arranged parallel to the polarization direction of the measured light (//). Thereto, (2941cm -1 intensity) based absorption spectrum to an absorbance minimum at 2770cm -1 and 2990cm -1 of absorbance at 2941cm -1 as the time of the baseline, (3330cm -1 intensity) based at 2990cm -1 and 3650cm -1 The absorbance at 3330cm -1 when used as the baseline. Use the obtained I ⊥ and I // to calculate the orientation function f according to formula 1. In addition, when f=1, it becomes fully oriented, and when f=0, it becomes random. In addition, the peak at 2941 cm -1 is considered to be absorption due to the vibration of the main chain (-CH 2 -) of PVA in the polarizing film. In addition, the peak at 3330 cm -1 is considered to be absorption due to the vibration of the hydroxyl group of PVA. (Equation 1) f=(3<cos2θ>-1)/2=(1-D)/[c(2D+1)] However, c=(3cos 2 β-1)/2, use 2941cm -1 as described above When β=90°⇒f=-2×(1-D)/(2D+1). θ: The angle of the molecular chain relative to the extension direction β: The angle of the transition dipole moment relative to the molecular chain axis D=(I ⊥ )/(I // ) I ⊥ : The polarization direction of the measured light and the extension direction of the polarizing film are Vertical absorption intensity I // : Measure the absorption intensity when the polarization direction of light is parallel to the extension direction of the polarizing film (3) The monomer transmittance and degree of polarization are determined by the polarizing film/thermoplastic resin used in the examples and comparative examples The laminated body of the substrate peels off the polarizing film, and uses an ultraviolet visible spectrophotometer ("V-7100" manufactured by JASCO Corporation) to measure the monomer transmittance Ts, parallel transmittance Tp, and orthogonal transmittance Tc of the polarized film. Each serves as the Ts, Tp and Tc of the polarizing film. These Ts, Tp, and Tc are Y values measured by JIS Z8701 2 degree field of view (C light source) and corrected for visual sensitivity. From the obtained Tp and Tc, the degree of polarization P is calculated by the following formula. Polarization degree P(%)={(Tp-Tc)/(Tp＋Tc)} 1/2 ×100 In addition, the same measurement can be performed with a spectrophotometer such as "LPF-200" manufactured by Otsuka Electronics Co., Ltd., and it has been confirmed that it can be used. A spectrophotometer can get the same measurement result. (4) Breaking strength The polarizing film was peeled off from the laminate of the polarizing film/thermoplastic resin substrate used in the Examples and Comparative Examples, and the polarizing film was loaded on a compression tester (manufactured by Kato-tech) with a puncture needle installed. , Product name "NDG5" puncture needle penetration force measurement model), puncture at room temperature (23℃±3℃) at a puncture speed of 0.33cm/sec. The strength when the polarizing film ruptures is used as the breaking strength (puncture strength). The evaluation value is to measure the breaking strength of 10 sample pieces, and use the average value. In addition, a puncture needle with a tip diameter of 1mmφ and 0.5R is used. For the polarizing film to be measured, a jig with a circular opening with a diameter of about 11 mm was clamped and fixed on both sides of the polarizing film, and a puncture needle was punctured in the center of the opening to perform the test. The breaking strength per unit thickness is used as the index of rupture difficulty and evaluated according to the following standards. ○: Breaking strength exceeds 30gf/μm ×: Breaking strength 30gf/μm or less
實施例1 熱塑性樹脂基材係使用長條狀、吸水率0.75%、Tg約75℃且非晶質之異酞酸共聚聚對苯二甲酸乙二酯薄膜(厚度：100μm)。於樹脂基材之單面施有電暈處理(處理條件：55W・min/m2 )。 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，添加碘化鉀13重量份，調製成PVA水溶液(塗佈液)。 於樹脂基材之電暈處理面塗佈上述PVA水溶液並以60℃乾燥，藉以形成厚度13μm之PVA系樹脂層，而製成積層體。 於130℃之烘箱內，將所得之積層體於圓周速度相異之輥間沿縱向(長邊方向)進行自由端單軸延伸成2.4倍(空中輔助延伸處理)。 接著，將積層體浸漬於液溫40℃之不溶化浴(相對於水100重量份摻合4重量份之硼酸而得之硼酸水溶液)中30秒(不溶化處理)。 接著，於液溫30℃之染色浴(相對於水100重量份以1：7之重量比摻合碘與碘化鉀所得之碘水溶液)中，調整濃度同時浸漬60秒以使最終所得之偏光膜之單體透射率(Ts)成為41.6%(染色處理)。 接著，於液溫40℃之交聯浴(相對於水100重量份摻合3重量份之碘化鉀、5重量份之硼酸所得之硼酸水溶液)中浸漬30秒(交聯處理)。 其後，將積層體浸漬於液溫62℃之硼酸水溶液(硼酸濃度4.0重量%，碘化鉀5.0重量%)，同時於圓周速度相異之輥間沿縱向(長邊方向)進行單軸延伸，使總延伸倍率成為3.0倍(水中延伸處理：水中延伸處理之延伸倍率為1.25倍)。 其後，將積層體浸漬於液溫20℃之洗淨浴中(相對於水100重量份摻合4重量份之碘化鉀所得之水溶液)中(洗淨處理)。 其後，令積層體於保持90℃之烘箱中乾燥的同時，使其接觸表面溫度保持75℃之SUS製加熱輥約2秒(乾燥收縮處理)。乾燥收縮處理所致之積層體之寬度方向收縮率為2%。 如此作業後，即於樹脂基材上形成厚度7.1μm之偏光膜。Example 1 As a thermoplastic resin substrate, an amorphous isophthalic acid copolymer polyethylene terephthalate film (thickness: 100 μm) with a water absorption rate of 0.75% and a Tg of about 75° C. was used. Corona treatment is applied to one side of the resin substrate (treatment conditions: 55W·min/m 2 ). The PVA system is a 9:1 mixture of polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetyl acetyl modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z410") To 100 parts by weight of the resin, 13 parts by weight of potassium iodide was added to prepare a PVA aqueous solution (coating liquid). The above-mentioned PVA aqueous solution was coated on the corona-treated surface of the resin substrate and dried at 60° C. to form a PVA-based resin layer with a thickness of 13 μm to form a laminate. In an oven at 130°C, the resulting laminate was uniaxially stretched to 2.4 times the free end in the longitudinal direction (longitudinal direction) between rollers with different circumferential speeds (air-assisted stretching treatment). Next, the layered body was immersed in an insolubilization bath (a boric acid aqueous solution obtained by blending 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 (insolubilization treatment). Next, in a dyeing bath with a liquid temperature of 30°C (an iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 to 100 parts by weight of water), adjust the concentration while immersing for 60 seconds to make the final polarized film The monomer transmittance (Ts) became 41.6% (dyeing treatment). Next, it was immersed in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment). After that, the layered body was immersed in a boric acid aqueous solution (boric acid concentration 4.0% by weight, potassium iodide 5.0% by weight) at a liquid temperature of 62°C, and simultaneously stretched uniaxially in the longitudinal direction (longitudinal direction) between rollers with different peripheral speeds to make The total stretching ratio becomes 3.0 times (underwater stretching treatment: the stretching ratio of underwater stretching treatment is 1.25 times). Thereafter, the layered body was immersed in a washing 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). After that, while drying the laminate in an oven maintained at 90°C, the contact surface temperature was maintained at 75°C with a heating roll made of SUS for about 2 seconds (drying shrinkage treatment). The width direction shrinkage rate of the laminate caused by the drying shrinkage treatment is 2%. After this operation, a polarizing film with a thickness of 7.1 μm is formed on the resin substrate.
關於所得之偏光膜之定向函數、單體透射率、偏光度及破斷強度如表1所示。Table 1 shows the orientation function, monomer transmittance, polarization degree and breaking strength of the obtained polarizing film.
實施例2 水中延伸處理之延伸倍率設為1.45倍、總延伸倍率設為3.5倍以外，以與實施例1相同方式，製作出厚度6.6μm之偏光膜。將所得之偏光膜供於與實施例1同樣之評估。結果表示於表1。Example 2 Except that the stretching ratio of the underwater stretching treatment was set to 1.45 times and the total stretching ratio was set to 3.5 times, in the same manner as in Example 1, a polarizing film with a thickness of 6.6 μm was produced. The obtained polarizing film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
實施例3 水中延伸處理之延伸倍率設為1.67倍、總延伸倍率設為4.0倍以外，以與實施例1相同方式，製作出厚度6.1μm之偏光膜。將所得之偏光膜供於與實施例1同樣之評估。結果表示於表1。Example 3 Except that the stretching ratio of the underwater stretching treatment was set to 1.67 times and the total stretching ratio was set to 4.0 times, in the same manner as in Example 1, a polarizing film with a thickness of 6.1 μm was produced. The obtained polarizing film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
實施例4 水中延伸處理之延伸倍率設為1.87倍、總延伸倍率設為4.5倍以外，以與實施例1相同方式，製作出厚度5.6μm之偏光膜。將所得之偏光膜供於與實施例1同樣之評估。結果表示於表1。Example 4 Except that the stretching ratio of the underwater stretching treatment was set to 1.87 times and the total stretching ratio was set to 4.5 times, in the same manner as in Example 1, a polarizing film with a thickness of 5.6 μm was produced. The obtained polarizing film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
比較例1 水中延伸處理之延伸倍率設為2.4倍、總延伸倍率設為5.5倍，及將延伸浴之液溫設為70℃以外，以與實施例1相同方式，製作出厚度5.0μm之偏光膜。且，所得偏光膜之寬度殘餘率為48%(寬度方向收縮率為52%)。將所得之偏光膜供於與實施例1同樣之評估。結果表示於表1。Comparative example 1 Except that the stretching ratio of the underwater stretching treatment was set to 2.4 times, the total stretching ratio was set to 5.5 times, and the liquid temperature of the stretching bath was set to 70°C, in the same manner as in Example 1, a polarizing film with a thickness of 5.0 μm was produced. In addition, the width residual rate of the obtained polarizing film was 48% (the shrinkage rate in the width direction was 52%). The obtained polarizing film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
比較例2 寬度殘餘率設為43%(寬度方向收縮率設為57%)以外，以與比較例1相同方式，製作出厚度5.5μm之偏光膜。將所得之偏光膜供於與實施例1同樣之評估。結果表示於表1。Comparative example 2 Except that the width residual rate was set to 43% (the shrinkage rate in the width direction was set to 57%), in the same manner as in Comparative Example 1, a polarizing film with a thickness of 5.5 μm was produced. The obtained polarizing film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
比較例3 將厚度30μm之PVA系樹脂薄膜(Kuraray製，製品名「PE3000」)長條卷材，藉由軋輥延伸機於長邊方向進行單軸延伸使總延伸倍率成為6.0倍，同時施以膨潤、染色、交聯及洗淨處理，最後實施乾燥處理，藉此製作出厚度12μm之偏光件。將所得之偏光件供於與實施例1同樣之評估。結果表示於表1。Comparative example 3 A long coil of PVA-based resin film (manufactured by Kuraray, product name "PE3000") with a thickness of 30μm is uniaxially stretched in the longitudinal direction by a roll stretcher to make the total stretch ratio 6.0 times, and swelling and dyeing are applied at the same time , Cross-linking and washing treatment, and finally drying treatment to produce a polarizer with a thickness of 12μm. The obtained polarizer was subjected to the same evaluation as in Example 1. The results are shown in Table 1.
表1
由表1可明瞭，本發明實施例之偏光膜具有實用上可接受的單體透射率及偏光度，並且沿吸收軸方向之破斷強度非常大。如此之破斷強度係代表偏光膜難以沿吸收軸方向裂開。It can be seen from Table 1 that the polarizing film of the embodiment of the present invention has practically acceptable monomer transmittance and polarization degree, and the breaking strength along the absorption axis is very high. Such breaking strength means that the polarizing film is difficult to crack along the absorption axis.
產業上之可利用性 本發明之偏光膜及偏光板係適用於液晶顯示裝置。Industrial availability The polarizing film and polarizing plate of the present invention are suitable for liquid crystal 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 R1~R6:輸送輥 G1~G4:導引輥10: Polarizing film 20: The first protective layer 30: The second protective layer 100: Polarizing plate 200: layered body R1~R6: conveyor roller G1~G4: guide roller
圖1係本發明之一實施型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。Fig. 1 is a schematic cross-sectional view of a polarizing plate of one embodiment of the present invention. Fig. 2 is a schematic diagram showing an example of drying shrinkage treatment using a heating roller.
10:偏光膜 10: Polarizing film
20:第1保護層 20: The first protective layer
30:第2保護層 30: The second protective layer
100:偏光板 100: Polarizing plate
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