Polarizing film, optical film and image display device

Abstract

A polarizing film comprising a polarizer and an adhesive layer adjacent to an optical film other than the polarizer, wherein, after a humidification durability test of being exposed for 1,000 hours in an environment of 65°C - 95% humidity, the polarizing film does not have a bright spot originating from foreign substances extending more than 3 mm from the cross-section. It is preferable that the polarizer contains a metal component capable of becoming a divalent metal cation in water, particularly zinc.

Description

Technology Field

[0001] The present invention relates to a polarizing film having a polarizer and an adhesive layer adjacent to an optical film other than the polarizer or the polarizer. The polarizing film can form an image display device such as a mobile phone, a car navigation device, a monitor for a personal computer, or a television, either alone or as an optical film laminated therewith. Background Technology

[0002] Liquid crystal displays are rapidly expanding into the market for mobile phones, car navigation systems, personal computer monitors, televisions, and the like. Liquid crystal displays visualize the polarization state resulting from the switching of liquid crystals, and polarizers are used in this display principle. In particular, for applications such as TVs, increasingly high brightness, high contrast, and wide viewing angles are required, and polarizing films are also increasingly required to have high transmittance, high polarization degree, and high color reproduction.

[0003] As for polarizers, iodine-based polarizers with a stretched structure in which iodine is adsorbed onto polyvinyl alcohol (hereinafter also simply referred to as "PVA") are most commonly and widely used due to their high transmittance and high polarization degree. Generally, a polarizing film is used in which a transparent protective film is laminated to both sides of a polarizer using a so-called water-based adhesive in which a polyvinyl alcohol-based material is dissolved in water (Patent Document 1 below). Triacetylcellulose, which has high moisture permeability, is used as the transparent protective film. When the above water-based adhesive is used (so-called wet lamination), a drying process is required after laminating the polarizer and the transparent protective film.

[0004] Meanwhile, instead of the above-mentioned water-based adhesive, an active energy beam curable adhesive has been proposed. When manufacturing a polarizing film using an active energy beam curable adhesive, the productivity of the polarizing film can be improved because a drying process is not required. For example, a radical polymerization type active energy beam curable adhesive using an N-substituted amide-based monomer as a curable component has been proposed (Patent Document 2 below). An adhesive layer formed using the active energy beam curable adhesive described in Patent Document 2 can sufficiently pass a water resistance test, for example, which evaluates the presence or absence of color fading or peeling after immersion in hot water at 60°C for 6 hours. However, recently, polarizing films are often used not only for mobile applications such as mobile phones but also for automotive image display devices. Therefore, for automotive applications, it is necessary to satisfy durability tests under higher temperature and higher humidity conditions compared to mobile applications. Prior art literature

[0005] Japanese Published Patent Application No. 2001-296427 Japanese Published Patent Application No. 2012-052000 The problem to be solved

[0006] As a durability test required for polarizing films used in automotive applications, there is, for example, a humidification durability test involving exposure for 1,000 hours under an environment of 65°C - 95% humidity. Here, the inventors examined in detail the appearance of the polarizing film after such humidification durability test and found that, particularly at the ends of the polarizing film, bright spots originating from white, hazy foreign substances occurred, resulting in product defects in terms of appearance characteristics. This phenomenon was observed for the first time after a durability test under high temperature and high humidity environments, and therefore, it was necessary to conduct a thorough examination to solve it anew.

[0007] The present invention was developed in consideration of the above circumstances and aims to provide a polarizing film with excellent appearance characteristics by suppressing the occurrence of bright spots originating from foreign substances even after a humidification durability test. means of solving the problem

[0008] The above problem can be solved by the following configuration. That is, the present invention relates to a polarizing film comprising a polarizer and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer, characterized in that, after a humidification durability test of being exposed for 1,000 hours in an environment of 65°C - 95% humidity, it does not have a bright spot originating from foreign substances extending more than 3 mm from the cross-section.

[0009] In the above polarizing film, it is preferable that the polarizer contains a metal component capable of becoming a divalent metal cation in water.

[0010] In the above polarizing film, it is preferable that the metal component is zinc.

[0011] In the above polarizing film, it is preferable that the polarizing film comprises a polarizer and an optical film laminated with a water-based adhesive layer interposed on at least one surface of the polarizer, and an adhesive layer on the surface of the optical film opposite to the water-based adhesive layer.

[0012] In the above polarizing film, it is preferable that the adhesive layer is formed by a cured layer of an active energy beam curable adhesive composition.

[0013] In the above polarizing film, the adhesive layer is formed by a cured layer of the adhesive composition, and when the cured product obtained by curing the adhesive composition is immersed in pure water at 23°C for 24 hours,

[0014] Formula : {(M2-M1) / M1}×100 (%),

[0015] However, M1: weight of the cured product before immersion, M2: weight of the cured product after immersion,

[0016] It is preferable that the bulk absorption rate represented by is less than 10 weight%.

[0017] In the above polarizing film, it is preferable that (number of carbon atoms) / (number of oxygen atoms + number of nitrogen atoms), based on the measurement of the elemental ratio of the adhesive layer, is 2.5 or higher.

[0018] In the above polarizing film, the adhesive layer is formed by a cured layer of the adhesive composition, and it is preferable that the logPow, which represents the octanol / water partition coefficient based on the weighted average of the mole fraction of the monomer component contained in the adhesive composition, is 1.6 or higher.

[0019] In the above polarizing film, it is preferable that the adhesive composition contains at least 25 parts by weight of a monomer component having an alkyl group having 8 or more carbon atoms, when the total amount of the monomer component is 100 parts by weight.

[0020] In the above polarizing film, it is preferable that the adhesive composition contains 40 parts by weight or less of a monomer component having a hydroxyl group when the total amount of the monomer component is 100 parts by weight.

[0021] In addition, the present invention relates to an optical film characterized by having at least one polarizing film described in any one of the above-mentioned films laminated therein, an optical film described in any one of the above-mentioned films, and / or an image display device characterized by using the optical film described in any one of the above-mentioned films. Effects of the invention

[0022] For polarizing films used for automotive applications, it is required that they have excellent appearance characteristics even after a humidification durability test in which they are exposed for 1,000 hours in an environment of 65°C - 95% humidity. The polarizing film related to the present invention has excellent appearance characteristics in that, after such a humidification durability test, it does not have bright spots originating from foreign substances extending more than 3 mm from the cross-section.

[0023] In particular, the polarizing film according to the present invention has excellent appearance characteristics even when it is equipped with a polarizer containing a metal component, particularly zinc, which can become a divalent metal cation in water. Although the reason for obtaining this effect is not clear, the following reasons can be inferred, for example.

[0024] In a polarizing film having a polarizer and an adhesive layer adjacent to an optical film other than the polarizer, during a humidification durability test, a metal component contained in the polarizer that can become a divalent metal cation in water, particularly zinc, migrates into the adhesive layer via steam or condensation at the end of the polarizing film. Here, components other than those contained in the raw adhesive composition, such as oxalic acid, exist in an ionized state within the adhesive layer; however, oxalic acid is not detected as a foreign substance within the adhesive layer unless it combines with the metal component to form an oxalate. However, during the humidification durability test, if a specific metal component contained in the polarizer is mixed into the adhesive layer from the end, the ionized oxalic acid combines with the metal component, causing an oxalate to form, particularly at the end of the adhesive layer, which appears as a white spot and is detected as a foreign substance. As a result, the appearance characteristics of the polarizing film deteriorate.

[0025] The polarizing film related to the present invention is a polarizing film comprising a polarizer and an adhesive layer adjacent to an optical film other than the polarizer, and does not have a bright spot originating from foreign substances extending more than 3 mm from the cross-section after a humidification durability test in which it is exposed for 1,000 hours under an environment of 65°C - 95% humidity. In particular, when the polarizer related to the present invention has an adhesive layer designed such that the bulk absorption rate of the cured layer of the adhesive composition used as a raw material is less than 10 weight%, even if a specific metal component contained in the polarizer is incorporated into the adhesive layer from the end, the binding of ionized oxalic acid with the metal component, and furthermore the migration of oxalate from the end of the polarizing film into the interior, is suppressed. As a result, the appearance characteristics of the polarizing film are particularly improved even after the humidification durability test.

[0026] In particular, the adhesive layer provided by the polarizing film related to the present invention is formed by a cured layer of the adhesive composition, and (i) when (number of carbon atoms) / (number of oxygen atoms + number of nitrogen atoms) based on the measurement of the elemental ratio of the adhesive layer is 2.5 or higher, or (ii) when the logPow representing the octanol / water partition coefficient based on the weighted average of the mole fraction of the monomer component contained in the adhesive composition is 1.6 or higher, the binding of ionized oxalic acid and metal components, and furthermore the migration of oxalates from the ends of the polarizing film into the interior, can be suppressed, especially at the ends of the adhesive layer. As a result, the appearance characteristics of the polarizing film are significantly improved even after a humidification durability test. Brief explanation of the drawing

[0027] FIG. 1 is an example of a schematic cross-sectional view of a polarizing film related to one embodiment of the present invention. FIG. 2 is another example of a schematic cross-sectional view of a polarizing film related to one embodiment of the present invention. Specific details for implementing the invention

[0028] FIG. 1 shows an example of a cross-sectional schematic diagram of a polarizing film related to an embodiment of the present invention. In this embodiment, the polarizing film (10) comprises a polarizer (1) and an adhesive layer (5) adjacent to a first optical film (4) other than the polarizer (1). More specifically, the polarizer (1) and a first optical film (phase difference film) (4) are laminated with a water-based adhesive layer (2) interposed on at least one surface of the polarizer (1), and an adhesive layer (5) is provided on the surface of the first optical film (4) opposite to the water-based adhesive layer (2). In particular, the polarizing film (10) of this embodiment has a second optical film (transparent protective film) (3) laminated on one side of the polarizer (1) with a water-based adhesive layer (2) interposed therebetween, a first optical film (phase difference film) (4) laminated on the other side of the polarizer (1) with a water-based adhesive layer (2) interposed therebetween, an adhesive layer (5) laminated on the first optical film (phase difference film) (4), and a third optical film (phase difference film) (6) laminated on the adhesive layer (5). The polarizing film (10) also has an adhesive layer (7) laminated on the third optical film (6), and is laminated to an image display cell, etc., with the adhesive layer (7) interposed therebetween.

[0029] FIG. 2 shows another example of a cross-sectional schematic diagram of a polarizing film related to one embodiment of the present invention. In this embodiment, the polarizing film (10) comprises a polarizer (1) and an adhesive layer (5) adjacent to the polarizer (1). More specifically, in this embodiment, the polarizing film (10) has a second optical film (transparent protective film) (3) laminated on one side of the polarizer (1) with a water-based adhesive layer (2) interposed therebetween, and a first optical film (phase difference film) (4) laminated on the other side of the polarizer (1) with an adhesive layer (5) interposed therebetween. The polarizing film (10) also has an adhesive layer (7) laminated on the optical film (4) and is laminated to an image display cell, etc., with the adhesive layer (7) interposed therebetween.

[0030] In the polarizing film shown in FIGS. 1 and 2, the water-based adhesive layer (2) preferably uses an aqueous solution of a water-based adhesive such as an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl latex-based adhesive, or a water-based polyester (e.g., with a solid content concentration of 0.5 to 60 wt%). The thickness of the water-based adhesive layer (2) is not particularly limited, but is typically about 0.01 μm to 0.5 μm after drying.

[0031] In the polarizing film (10) shown in FIGS. 1 and 2, during a humidification durability test, a metal component, particularly zinc, which can become a divalent metal cation in water, contained in the polarizer (1), moves into the adhesive layer (5) via steam or condensation at the end of the polarizing film (10). Here, in the adhesive layer (5), a component other than the component contained in the raw adhesive composition, for example, oxalic acid, exists in an ionized state, but oxalic acid is not detected as a foreign substance in the adhesive layer unless it combines with the metal component to become an oxalate. Here, when a specific metal component contained in the polarizer (10) is mixed into the adhesive layer (5) during a humidification durability test, oxalate is generated by combining the ionized oxalic acid and the metal component, resulting in a white spot that is detected as a foreign substance. However, the polarizing film (10) shown in FIGS. 1 and 2 does not have a spot originating from a foreign substance exceeding 3 mm from the cross-section, more preferably exceeding 2 mm from the cross-section, after a humidification durability test in which it is exposed for 1000 hours in an environment of 65 ℃ - 95% humidity.

[0032] Hereinafter, each component of the polarizing film related to the present invention is described. In the present invention, the polarizing film comprises a polarizer and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer.

[0033] Polarizer

[0034] Polyvinyl alcohol or its derivatives are used as materials for polyvinyl alcohol-based films applied to polarizers. Examples of polyvinyl alcohol derivatives include polyvinyl formal and polyvinyl acetal, as well as derivatives modified by olefins such as ethylene and propylene, alkyl esters of unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, and acrylamide. Polyvinyl alcohol with a degree of polymerization of approximately 1,000 to 10,000 and a degree of saponification of approximately 80 to 100 mol% is generally used.

[0035] The polyvinyl alcohol-based film may contain additives such as plasticizers. Examples of plasticizers include polyols and their condensates, such as glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. The amount of plasticizer used is not particularly limited, but it is preferably 20 weight percent or less of the polyvinyl alcohol-based film.

[0036] In the manufacture of a polarizer, a dyeing process in which the polyvinyl alcohol-based film is dyed with iodine and a stretching process in which the polyvinyl alcohol-based film is stretched in at least one direction are carried out. Generally, a method is employed in which the polyvinyl alcohol-based film is subjected to a series of processes including swelling, dyeing, crosslinking, stretching, washing, and drying.

[0037] The swelling process is carried out, for example, by immersing a polyvinyl alcohol-based film in a swelling bath (water bath). Through this treatment, contamination or anti-blocking agents on the surface of the polyvinyl alcohol-based film are cleaned, and non-uniformity such as uneven dyeing can be prevented by swelling the polyvinyl alcohol-based film. Glycerin or potassium iodide may be appropriately added to the swelling bath. The temperature of the swelling bath is typically about 20 to 60°C, and the immersion time in the swelling bath is typically about 0.1 to 10 minutes.

[0038] The dyeing process is carried out, for example, by immersing a polyvinyl alcohol-based film in an iodine solution. The iodine solution is typically an aqueous iodine solution containing iodine and potassium iodide as a solubilizing agent. The iodine concentration is typically about 0.01 to 1 weight%, and is preferably 0.02 to 0.5 weight%. The potassium iodide concentration is typically about 0.01 to 10 weight%, and is preferably 0.02 to 8 weight%.

[0039] In the iodine dyeing process, the temperature of the iodine solution is typically around 20 to 50°C, preferably 25 to 40°C. The immersion time is typically in the range of 10 to 300 seconds, preferably 20 to 240 seconds. In the iodine dyeing treatment, it is desirable to adjust conditions such as the concentration of the iodine solution, the immersion temperature of the polyvinyl alcohol-based film in the iodine solution, and the immersion time so that the iodine content and potassium content in the polyvinyl alcohol-based film are within the above ranges.

[0040] The crosslinking process is carried out, for example, by immersing an iodine-dyed polyvinyl alcohol-based film in a treatment bath containing a crosslinking agent. Any suitable crosslinking agent may be employed. Specific examples of crosslinking agents include boron compounds such as boric acid and borax, glyoxal, glutaraldehyde, etc. These are used alone or in combination. Water is generally used as the solvent for the crosslinking bath solution, but an appropriate amount of an organic solvent compatible with water may also be added. The crosslinking agent is typically used in a ratio of 1 to 10 parts by weight per 100 parts by weight of the solvent. It is preferable that the crosslinking bath solution further contain an auxiliary agent such as an iodide. The concentration of the auxiliary agent is preferably 0.05 to 15 weight%, more preferably 0.5 to 8 weight%. The temperature of the crosslinking bath is typically about 20 to 70°C, preferably 40 to 60°C. The immersion time in the crosslinking bath is typically 1 second to 15 minutes, preferably 5 seconds to 10 minutes.

[0041] The stretching process is a process in which a polyvinyl alcohol-based film is stretched in at least one direction. Generally, the polyvinyl alcohol-based film is uniaxially stretched in the conveying direction (length direction). The stretching method is not particularly limited, and either wet stretching or dry stretching methods may be employed. When a wet stretching method is employed, the polyvinyl alcohol-based film is stretched at a predetermined ratio in a treatment bath. As the solution for the stretching bath, a solution in which compounds necessary for various treatments are added to a solvent such as water or an organic solvent (e.g., ethanol) is preferably used. Examples of dry stretching methods include roll-to-roll stretching, heated roll stretching, and compression stretching. In the manufacture of a polarizer, the stretching process may be performed at any stage. Specifically, it may be performed simultaneously with swelling, dyeing, and crosslinking, or it may be performed either before or after each of these processes. Furthermore, stretching may be performed in multiple stages. The cumulative stretching ratio of the polyvinyl alcohol-based film is typically 5 times or more, and preferably about 5 to 7 times.

[0042] In the present invention, it is preferable that the polarizer contains a metal component capable of becoming a divalent metal cation in water, more preferable that it contains magnesium, calcium, copper, or zinc, and particularly preferable that it contains zinc. By containing zinc in the polarizer, the decrease in transmittance and color degradation of the polarizing film after a heating test tend to be suppressed. When the polarizer contains zinc, the zinc content in the polarizer is preferably 0.002 to 2 weight%, and more preferable to 0.01 to 1 weight%.

[0043] In the present invention, it is preferable that the polarizer contains sulfate ions. By containing sulfate ions in the polarizer, the decrease in transmittance of the polarizing film after a heating test tends to be suppressed. When the polarizer contains sulfate ions, the content of sulfate ions in the polarizer is preferably 0.02 to 0.45 weight%, more preferably 0.05 to 0.35 weight%, and even more preferably 0.1 to 0.25 weight%. In addition, the content of sulfate ions in the polarizer is calculated from the sulfur atom content.

[0044] In order to incorporate zinc into the polarizer, it is preferable to perform zinc impregnation treatment during the manufacturing process of the polarizer. Additionally, in order to incorporate sulfate ions into the polarizer, it is preferable to perform sulfate ion treatment during the manufacturing process of the polarizer.

[0045] Zinc impregnation treatment is carried out, for example, by immersing a polyvinyl alcohol-based film in a zinc salt solution. Suitable zinc salts include inorganic salt compounds in aqueous solutions such as zinc halides (zinc chloride, zinc iodide, etc.), zinc sulfate, zinc acetate, etc. Additionally, various zinc complex compounds may be used for the zinc impregnation treatment. Furthermore, it is preferable to use an aqueous solution containing potassium ions and iodide ions, such as potassium iodide, as the zinc salt solution facilitates the impregnation of zinc ions. It is preferable to set the concentration of potassium iodide in the zinc salt solution to approximately 0.5 to 10 weight%, and further to 1 to 8 weight%.

[0046] Sulfate ion treatment is performed, for example, by immersing a polyvinyl alcohol-based film in an aqueous solution containing a metal sulfate salt. As for the metal sulfate salt, it is preferable that it is easily separated into sulfate ions and metal ions in the treatment solution and that the metal sulfate salt is easily introduced into the polyvinyl alcohol-based film in an ionic state. For example, types of metals that form the metal sulfate salt include alkali metals such as sodium and potassium; alkaline earth metals such as magnesium and calcium; and transition metals such as cobalt, nickel, zinc, chromium, aluminum, copper, manganese, and iron.

[0047] In the manufacture of a polarizer, the zinc impregnation treatment and the sulfate ion treatment may be performed at any stage. That is, the zinc impregnation treatment and the sulfate ion treatment may be performed before the dyeing process or after the dyeing process. The zinc impregnation treatment and the sulfate ion treatment may also be performed simultaneously. In the present invention, it is preferable to perform the zinc impregnation treatment and the sulfate ion treatment simultaneously by using zinc sulfate as the zinc salt and the metal sulfate salt, and by immersing a polyvinyl alcohol-based film in a treatment bath containing zinc sulfate. Additionally, the zinc salt or the metal sulfate salt may coexist in a dyeing solution, and the zinc impregnation treatment and / or the sulfate ion treatment may be performed simultaneously with the dyeing process. The zinc impregnation treatment and the sulfate ion treatment may also be performed simultaneously with stretching.

[0048] In zinc impregnation and sulfate ion treatment, the zinc content and sulfate ion content in the polarizer are adjusted by adjusting conditions such as the concentration of the zinc salt solution and the metal sulfate salt solution, the immersion temperature of the polyvinyl alcohol-based film in the treatment bath, and the immersion time. In zinc impregnation and sulfate ion treatment, the temperature of the zinc salt solution and the metal sulfate salt solution is typically 15 to 85°C, preferably 25 to 70°C. The immersion time is typically in the range of 1 to 120 seconds, preferably 3 to 90 seconds. The concentration of the zinc salt solution and the metal sulfate salt solution varies depending on the type of zinc salt or metal sulfate salt, but is typically 0.5 to 20 weight%, preferably 1 to 10 weight%, and more preferably 2 to 7 weight%. By setting the zinc salt concentration and the metal sulfate salt concentration to the said range, the zinc content and sulfate ion content in the polarizer can be kept within the above-mentioned preferred range.

[0049] The polyvinyl alcohol-based film (stretched film) subjected to each of the above treatments is provided to a water washing process and a drying process according to conventional methods.

[0050] The washing process is typically carried out by immersing a polyvinyl alcohol-based film in a washing bath. The washing bath may be pure water or an aqueous solution of iodide (e.g., potassium iodide, sodium iodide, etc.). The concentration of the aqueous iodide solution is preferably 0.1 to 10 weight%. An auxiliary agent such as zinc sulfate or zinc chloride may be added to the aqueous iodide solution.

[0051] The rinsing temperature is typically in the range of 5 to 50°C, preferably 10 to 45°C, and more preferably 15 to 40°C. The immersion time is typically about 10 to 300 seconds, preferably 20 to 240 seconds. The rinsing process may be performed only once, or multiple times if necessary. When the rinsing process is performed multiple times, the type or concentration of additives contained in the rinsing bath used for each treatment is appropriately adjusted.

[0052] The drying process of the polyvinyl alcohol-based film is carried out by any suitable method (e.g., natural drying, air drying, heat drying). The thickness of the polarizer after the drying process is preferably 3 to 20 μm.

[0053] In the present invention, a surface modification treatment may be performed on the obtained polarizer. Examples of surface modification treatments include corona treatment, plasma treatment, and ytro treatment, and corona treatment is particularly preferred. By performing corona treatment, reactive functional groups such as carbonyl groups or amino groups are generated on the surface of the polarizer, thereby improving adhesion with the durability enhancement layer. In addition, foreign substances on the surface are removed or surface irregularities are reduced due to the ashing effect, thereby enabling the production of a polarizing film with excellent appearance characteristics.

[0054] In the present invention, the polarizing film comprises a polarizer and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer. In the polarizing film (10) shown in FIG. 1, an adhesive layer adjacent to an optical film (phase difference film) (4) other than the polarizer (1) is provided. In addition, in the polarizing film (10) shown in FIG. 2, an adhesive layer (5) adjacent to the polarizer (1) is provided. The adhesive layer is described below.

[0055] <Adhesive layer>

[0056] The adhesive layer is formed by a cured layer of an adhesive composition, and is particularly preferably formed by a cured layer of an active energy beam curable adhesive composition, such as electron beam curable, ultraviolet curable, or visible light curable. Regarding the thickness of the adhesive layer after drying, from the perspective of improving the appearance characteristics of the polarizing film, it is preferable to have a thickness of 0.01 μm to 5 μm, and more preferable to have a thickness of 0.01 μm to 3 μm. Active energy beam curable adhesive compositions can be classified into radical polymerization curable adhesive compositions and cation polymerizable adhesive compositions. In the present invention, active energy beams with a wavelength range of less than 10 nm to 380 nm are referred to as ultraviolet light, and active energy beams with a wavelength range of 380 nm to 800 nm are referred to as visible light.

[0057] Examples of monomer components constituting a radical polymerization-curing adhesive composition include radical polymerizable compounds. Examples of radical polymerizable compounds include compounds having radical polymerizable functional groups of carbon-carbon double bonds, such as (meth)acryloyl groups and vinyl groups. As these monomer components, either monofunctional radical polymerizable compounds or polyfunctional radical polymerizable compounds having two or more polymerizable functional groups may be used. Furthermore, these radical polymerizable compounds may be used individually or in combination of two or more types. For example, compounds having (meth)acryloyl groups are preferred as these radical polymerizable compounds. In addition, in the present invention, "(meth)acryloyl" means an acryloyl group and / or a methacryloyl group, and "(meth)" has the same meaning below.

[0058] Examples of monofunctional radical polymerizable compounds include (meth)acrylamide derivatives having (meth)acrylamide groups. (meth)acrylamide derivatives are desirable for ensuring adhesion to polarizers or various transparent protective films, and also for their high polymerization rate and excellent productivity. Specific examples of (meth)acrylamide derivatives include, for example, N-alkyl group containing (meth)acrylamide derivatives such as N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, and N-hexyl(meth)acrylamide; and N-hydroxyalkyl group containing (meth)acrylamide derivatives such as N-methylol(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, and N-methylol-N-propane(meth)acrylamide. Examples include (meth)acrylamide derivatives containing N-aminoalkyl groups such as aminomethyl(meth)acrylamide and aminoethyl(meth)acrylamide; (meth)acrylamide derivatives containing N-alkoxy groups such as N-methoxymethylacrylamide and N-ethoxymethylacrylamide; (meth)acrylamide derivatives containing N-mercaptoalkyl groups such as mercaptomethyl(meth)acrylamide and mercaptoethyl(meth)acrylamide; etc. In addition, examples of (meth)acrylamide derivatives containing a complex ring in which the nitrogen atom of the (meth)acrylamide group forms a complex ring include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine, etc.

[0059] Among the above (meth)acrylamide derivatives, an N-hydroxyalkyl group-containing (meth)acrylamide derivative is preferred in terms of adhesion to polarizers or various transparent protective films, and as a monofunctional radical polymerizable compound, examples include various (meth)acrylic acid derivatives having a (meth)acryloyloxy group. Specifically, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, 2-methyl-2-nitropropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, t-pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 4-methyl-2-propylpentyl (meth)acrylate, Examples include (meth)acrylic acid (carbon 1-20) alkyl esters such as n-octadecyl (meth)acrylate.

[0060] In addition, the above (meth)acrylic acid derivatives include, for example, cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate and cyclopentyl (meth)acrylate; aralkyl (meth)acrylates such as benzyl (meth)acrylate; polycyclic (meth)acrylates such as 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornene-2-yl-methyl (meth)acrylate, 3-methyl-2-norbornylmethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and dicyclofentanyl (meth)acrylate; Examples include (meth)acrylates containing alkoxy groups or phenoxy groups, such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxymethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phenoxyethyl (meth)acrylate, and alkylphenoxypolyethylene glycol (meth)acrylate.

[0061] In addition, the above (meth)acrylic acid derivatives include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate, or hydroxyl group-containing (meth)acrylates such as [4-(hydroxymethyl)cyclohexyl]methylacrylate, cyclohexanedimethanol mono(meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate; (Meth)acrylates containing epoxy groups, such as glycidyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate glycidyl ether; (meth)acrylates containing halogens, such as 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethyl ethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate; and alkylaminoalkyl (meth)acrylates, such as dimethylaminoethyl (meth)acrylate. Examples include oxetane group-containing (meth)acrylates such as 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth)acrylate, 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, and 3-hexyl-oxetanylmethyl (meth)acrylate; (meth)acrylates having a complex ring such as tetrahydrofurfuryl (meth)acrylate and butyrolactone (meth)acrylate; hydroxypivalate neopentyl glycol (meth)acrylate adducts; and p-phenylphenol (meth)acrylate.

[0062] In addition, monofunctional radical polymerizable compounds include carboxyl group-containing monomers such as (meth)acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

[0063] In addition, monofunctional radical polymerizable compounds include, for example, lactam-based vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; and vinyl-based monomers having a nitrogen-containing heterocyclic ring such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine.

[0064] In addition, as a monofunctional radical polymerizable compound, a radical polymerizable compound having an active methylene group may be used. A radical polymerizable compound having an active methylene group is a compound having an active double bond group, such as a (meth)acryl group, at the terminal or within the molecule, and also having an active methylene group. Examples of active methylene groups include an acetoacetyl group, an alkoxymalonyl group, or a cyanoacetyl group. It is preferable that the active methylene group is an acetoacetyl group. Specific examples of radical polymerizable compounds having an active methylene group include, for example, acetoacetoxyalkyl (meth)acrylates such as 2-acetoacetoxyethyl (meth)acrylate, 2-acetoacetoxypropyl (meth)acrylate, and 2-acetoacetoxy-1-methylethyl (meth)acrylate; Examples include 2-ethoxymalonyloxyethyl (meth)acrylate, 2-cyanoacetoxyethyl (meth)acrylate, N-(2-cyanoacetoxyethyl)acrylamide, N-(2-propionylacetoxybutyl)acrylamide, N-(4-acetoacetoxymethylbenzyl)acrylamide, N-(2-acetoacetylaminoethyl)acrylamide, etc. The radical polymerizable compound having an active methylene group is preferably acetoacetoxyalkyl (meth)acrylate.

[0065] In addition, polyfunctional radical polymerizable compounds having two or more polymerizable functional groups include, for example, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol diacrylate, 2-ethyl-2-butylpropanediol di(meth)acrylate, bisphenol A di(meth)acrylate, bisphenol A ethylene oxide adduct di(meth)acrylate, bisphenol A propylene oxide adduct di(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate, neopentyl glycol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, cyclic trimethylolpropaneformal (meth)acrylate, Examples include esters of (meth)acrylic acid and polyhydric alcohols such as dioxane glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and EO-modified diglycerin tetra(meth)acrylate, and 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene. Specific examples include Aronics M-220 (manufactured by Toa Synthetic Co.), Light Acrylate 1,9ND-A (manufactured by Kyoei Chemical Co.), Light Acrylate DGE-4A (manufactured by Kyoei Chemical Co.), Light Acrylate DCP-A (manufactured by Kyoei Chemical Co.), SR-531 (manufactured by Sarcomer), CD-536 (manufactured by Sarcomer), etc. Additionally, depending on the need, various epoxy (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates, or various (meth)acrylate-based monomers may be used.

[0066] In the present invention, the polarizing film comprises a polarizer and an adhesive layer adjacent to an optical film other than the polarizer or the polarizer, wherein the adhesive layer is formed by a cured layer of an adhesive composition, and when a cured product obtained by curing the adhesive composition is immersed in pure water at 23°C for 24 hours,

[0067] Formula : {(M2-M1) / M1}×100 (%),

[0068] However, M1: weight of the cured product before immersion, M2: weight of the cured product after immersion,

[0069] It is preferable that the bulk absorption rate, as indicated by [the formula], is less than 10 weight%. According to this composition, even when a specific metal component contained in the polarizer is incorporated into the adhesive layer from the end, the binding of ionized oxalic acid with the metal component, and furthermore the migration of oxalates from the end of the polarizing film into the interior, is suppressed. As a result, the appearance characteristics of the polarizing film are particularly improved even after a humidification durability test. It is more preferable that the bulk absorption rate is less than 8 weight%, and particularly preferable that it is less than 6 weight%.

[0070] In the present invention, the polarizing film comprises a polarizer and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer, and it is preferable that the ratio of (number of carbon atoms) / (number of oxygen atoms + number of nitrogen atoms), based on the measurement of the elemental ratio of the adhesive layer, is 2.5 or higher. Generally, it is believed that the bonding of ionized oxalic acid with metal components, and furthermore the movement of oxalates, occurs through water. Here, if the ratio of (number of carbon atoms) / (number of oxygen atoms + number of nitrogen atoms), based on the measurement of the elemental ratio of the adhesive layer, is 2.5 or higher, the intrusion of water into the adhesive layer from the ends is suppressed, thereby suppressing the bonding of ionized oxalic acid with metal components, particularly at the ends of the adhesive layer, and furthermore the movement of oxalates from the ends of the polarizing film into the interior. As a result, the appearance characteristics of the polarizing film are significantly improved even after a humidification durability test. A method for measuring the elemental ratio of the adhesive layer will be described later.

[0071] In addition, in the present invention, the polarizing film comprises a polarizer and an adhesive layer adjacent to an optical film other than the polarizer or the polarizer, wherein the adhesive layer is formed by a cured layer of an adhesive composition, and it is preferable that the logPow, which represents the octanol / water partition coefficient based on the weighted average of the mole fraction of the monomer component contained in the adhesive composition, is 1.6 or higher. Generally, it is believed that the binding of ionized oxalic acid and metal components, and furthermore the movement of oxalates, occurs through water. Here, when the logPow, which represents the octanol / water partition coefficient based on the weighted average of the mole fraction of the monomer component contained in the adhesive composition, is 1.6 or higher, the intrusion of water from the end into the adhesive layer is suppressed, thereby suppressing the binding of ionized oxalic acid and metal components, and furthermore the movement of oxalates from the end into the polarizing film, particularly at the end of the adhesive layer. As a result, the appearance characteristics of the polarizing film are significantly improved even after a humidification durability test.

[0072] The octanol / water partition coefficient (logPow) is an indicator of the lipophilicity of a substance and represents the logarithm of the octanol / water partition coefficient. A high logPow indicates lipophilicity, meaning a low absorption rate. While the logPow value can be measured (using the flask shaking method described in JIS-Z-7260), it can also be calculated. In this specification, the logPow value calculated using Chem Draw Ultra manufactured by Cambridge Soft is used.

[0073] The logPow of the main radical polymerizable compounds is shown below. Hydroxyethylacrylamide (Trade name "HEAA", manufactured by Kojin, LogPow; -0.56), Diethylacrylamide (Trade name "DEAA", manufactured by KJ Chemicals, LogPow; 1.69), Unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone (Trade name "Fraxel FA1DDM", manufactured by Daicel, LogPow; 1.06), N-vinylformamide (Trade name "Beamset 770", manufactured by Arakawa Chemical, LogPow; -0.25), Acryloylmorpholine (Trade name "ACMO", manufactured by Kojin, LogPow; -0.20), γ-butyrolactone acrylate (Trade name "GBLA", manufactured by Osaka Organic Chemical Industry, LogPow; 0.19), Acrylic acid dimer (Trade name "β-CEA", manufactured by Daicel, LogPow; 0.2), N-vinylpyrrolidone (trade name "NVP", manufactured by Nippon Sokaksha Co., Ltd., LogPow; 0.24), acetoacetoxyethyl methacrylate (trade name "AAEM", manufactured by Nippon Synthetic Chemical Co., Ltd., LogPow; 0.27), 2-hydroxyethyl acrylate (trade name "HEA", manufactured by Osaka Organic Chemical Industry Co., Ltd., LogPow; 0.28), glycidyl methacrylate (trade name "Right Ester G", manufactured by Kyoeisha Chemical, LogPow; 0.57), dimethylacrylamide (trade name "DMAA", manufactured by Kojin Co., Ltd., LogPow; 0.58), tetrahydrofurfuryl alcohol acrylic acid polymer ester (trade name "Viscot #150D", manufactured by Osaka Organic Chemical Industry Co., Ltd., LogPow; 0.60), 4-hydroxybutyl acrylate (trade name "4-HBA", manufactured by Osaka Organic Chemical Industry Co., Ltd., LogPow ; 0.68), acrylic acid (trade name "Acrylic Acid", manufactured by Mitsubishi Chemical Co., Ltd., LogPow ; 0.69), triethylene glycol diacrylate (trade name "Light Acrylate 3EG-A", manufactured by Kyoei Chemical Co., Ltd., LogPow ; 0.72), PEG400# diacrylate (trade name "Light Acrylate 9EG-A", manufactured by Kyoeisha Chemical Co., Ltd., LogPow ; -0.1) Polypropylene glycol diacrylate (trade name "Aronix M-220", manufactured by Toa Synthetic Co., Ltd., LogPow ; 1.68), dicyclofentanyl acrylate (trade name "Pancryl FA-511AS", manufactured by Hitachi Chemical Co., Ltd., LogPow ; 2.26), butyl acrylate (trade name "Butyl Acrylate", manufactured by Mitsubishi Chemical Co., Ltd., LogPow ; 2.35), 1,6-hexanediol diacrylate (trade name "Light Acrylate 1.6HX-A", manufactured by Kyoeisha Chemical Co., Ltd., LogPow ; 2.43), dicyclofentanyl acrylate (trade name "Pancryl FA-513AS", manufactured by Hitachi Chemical Co., Ltd., LogPow ; 2.58), dimethylol-tricyclodecane diacrylate (trade name "Light Acrylate DCP-A", manufactured by Kyoeisha Chemical Co., Ltd., LogPow; 3.05), isobornyl acrylate (trade name "Light Acrylate IB-XA", manufactured by Kyoeisha Chemical Co., Ltd., LogPow; 3.27), hydroxypivalsan neopentylglycol acrylic acid adduct (trade name "Light Acrylate HPP-A", manufactured by Kyoeisha Chemical Co., Ltd., LogPow; 3.35), 1,9-nonanediol diacrylate (trade name "Light Acrylate 1,9ND-A", manufactured by Kyoeisha Chemical Co., Ltd., LogPow; 3.68), o-phenylphenol EO-modified acrylate (trade name "Pancryl FA-301A", manufactured by Hitachi Chemical Co., Ltd., LogPow; 3.98), 2-ethylhexyl oxetane (trade name "Aronoxetane OXT-212", manufactured by Toa Synthetic Co., Ltd., LogPow; 4.24), bisphenol-A-diglycidyl ether (trade name "JER828", manufactured by Mitsubishi Chemical, LogPow; 4.76), bisphenol A EO 6-mol modified diacrylate (trade name "FA-326A", manufactured by Hitachi Chemical, LogPow; 4.84), bisphenol A EO 4-mol modified diacrylate (trade name "FA-324A", manufactured by Hitachi Chemical, LogPow; 5.Examples include 15), bisphenol A PO 2 molar modified diacrylate (product name “FA-P320A”, manufactured by Hitachi Chemical Co., Ltd., LogPow; 6.10), bisphenol A PO 3 molar modified diacrylate (product name “FA-P323A”, manufactured by Hitachi Chemical Co., Ltd., LogPow; 6.26), bisphenol A PO 4 molar modified diacrylate (product name “FA-P324A”, manufactured by Hitachi Chemical Co., Ltd., LogPow; 6.43), lauryl acrylate (product name “Light Acrylate LA”, manufactured by Kyoei Chemical Co., Ltd., LogPow; 6), isostearyl acrylate (product name “ISTA”, manufactured by Osaka Organic Chemical Industry Co., Ltd.; LogPow; 7.46).

[0074] In order for the adhesive layer to be formed by the cured layer of the adhesive composition and for the logPow value representing the octanol / water partition coefficient based on the weighted average of the mole fractions of the monomer components contained in the adhesive composition to be 1.6 or higher, it is preferable to contain 25 parts by weight or more of a monomer component having an alkyl group having 8 or more carbon atoms when the total amount of monomer components is 100 parts by weight. Examples of monomer components having an alkyl group having 8 or more carbon atoms include the aforementioned dicyclofentanyl acrylate (product name "Pancryl FA-513AS", manufactured by Hitachi Chemical Co., Ltd., LogPow; 2.58), lauryl acrylate (product name "Light Acrylate LA", manufactured by Kyoei Chemical Co., Ltd., LogPow; 6), and isostearyl acrylate (product name "ISTA", manufactured by Osaka Organic Chemical Industry Co., Ltd.; LogPow; 7.46).

[0075] In order for the adhesive layer to be formed by the cured layer of the adhesive composition, and for the logPow representing the octanol / water partition coefficient based on the weighted average of the mole fractions of the monomer components contained in the adhesive composition to be 1.6 or higher, it is preferable to have the content of the monomer component having a hydroxyl group 40 parts by weight or less. In addition, among the monomer components having a hydroxyl group, the monomer component having a hydroxyl group may be cited as the monomer component having a hydroxyl group.

[0076] In addition, in the present invention, the polarizing film comprises a polarizer and an adhesive layer adjacent to an optical film other than the polarizer or the polarizer, wherein the adhesive layer is formed by a cured layer of an adhesive composition, and it is preferable that the adhesive composition contains 25 parts by weight or more of a monomer component having two or more polymerizable functional groups when the total amount of the monomer component is 100 parts by weight, and more preferable that it contains 30 parts by weight or more. Even if, for example, oxalates are generated, the crystal growth of oxalates is inhibited because the hardness of the adhesive layer is high. As a result, the generation of foreign substances originating from oxalates is suppressed, and the appearance characteristics of the polarizing film are significantly improved.

[0077] Examples of monomer components having two or more polymerizable functional groups include polyfunctional radical polymerizable compounds having two or more of the aforementioned polymerizable functional groups. In particular, when the total amount of monomer components in the adhesive composition is 100 parts by weight, and the monomer component having two or more polymerizable functional groups is 25 parts by weight or more, it is preferable to keep the content of the monomer component having hydroxyl groups at 40 parts by weight or less.

[0078] In the present invention, the adhesive composition serving as a raw material for the adhesive layer of the polarizing film may contain, in addition to a radical polymerizable compound, an acrylic oligomer formed by polymerizing a (meth)acrylic monomer. By including the acrylic oligomer in the adhesive composition, the curing shrinkage when the composition is irradiated with active energy rays and cured can be reduced, and the interfacial stress between the adhesive layer and the substrate, such as a polarizer and a transparent protective film, can be reduced. As a result, the deterioration of the adhesion between the adhesive layer and the substrate can be suppressed.

[0079] Since it is desirable for active energy beam curing adhesives to have low viscosity when considering workability or uniformity during coating, it is also desirable for the acrylic oligomer formed by polymerizing (meth)acrylic monomers to have low viscosity. As for the acrylic oligomer that has low viscosity and can also prevent curing shrinkage of the adhesive layer, it is desirable for the weight average molecular weight (Mw) to be 15,000 or less, more desirable for it to be 10,000 or less, and particularly desirable for it to be 5,000 or less. Meanwhile, in order to sufficiently suppress curing shrinkage of the cured layer (adhesive layer), it is desirable for the weight average molecular weight (Mw) of the acrylic oligomer to be 500 or more, more desirable for it to be 1,000 or more, and particularly desirable for it to be 1,500 or more. The (meth)acrylic monomers constituting the acrylic oligomers are, specifically, for example, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, 2-methyl-2-nitropropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, S-butyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, t-pentyl (meth)acrylate, 3-pentyl (meth)acrylate, 2,2-dimethylbutyl (meth)acrylate, n-hexyl (meth)acrylate, cetyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate. (Meth)acrylic acid (1-20 carbon atoms) alkyl esters such as 4-methyl-2-propylpentyl (meth)acrylate, N-octadecyl (meth)acrylate, etc., also, for example, cycloalkyl (meth)acrylates (e.g., cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, etc.), aralkyl (meth)acrylates (e.g., benzyl (meth)acrylate, etc.), polycyclic (meth)acrylates (e.g., 2-isobornyl (meth)acrylate, 2-norbornylmethyl (meth)acrylate, 5-norbornene-2-yl-methyl (meth)acrylate,3-methyl-2-norbornylmethyl(meth)acrylate, etc.), hydroxyl group-containing (meth)acrylic acid esters (e.g., hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2,3-dihydroxypropylmethyl-butyl(meth)acrylate, etc.), alkoxy or phenoxy group-containing (meth)acrylic acid esters (2-methoxyethyl(meth)acrylate, 2-ethoxyethyl(meth)acrylate, 2-methoxymethoxyethyl(meth)acrylate, 3-methoxybutyl(meth)acrylate, ethylcarbitol(meth)acrylate, phenoxyethyl(meth)acrylate, etc.), epoxy group-containing (meth)acrylic acid esters (e.g., glycidyl(meth)acrylate, etc.), halogen-containing Examples include (meth)acrylic acid esters (e.g., 2,2,2-trifluoroethyl (meth)acrylate, 2,2,2-trifluoroethylethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, etc.), alkylaminoalkyl (meth)acrylates (e.g., dimethylaminoethyl (meth)acrylate, etc.). These (meth)acrylates may be used alone or in combination of two or more types. Specific examples of acrylic oligomers (E) include "ARUFON" manufactured by Toa Synthetic Co., Ltd., "Actflow" manufactured by Soken Chemical Co., Ltd., and "JONCRYL" manufactured by BASF Japan.

[0080] The amount of acrylic oligomer incorporated is preferably typically 15 parts by weight or less per 100 parts by weight of the total amount of monomer components in the adhesive composition. If the content of acrylic oligomer in the adhesive composition is excessively high, the reaction rate decreases violently when the composition is irradiated with active energy rays, which may result in curing failure. On the other hand, in order to sufficiently suppress the curing shrinkage of the adhesive layer, it is preferable to contain 3 parts by weight or more of acrylic oligomer in the composition.

[0081] When using radical polymerizable compounds, the photopolymerization initiator is appropriately selected according to the activation energy line. When curing by ultraviolet or visible light, a photopolymerization initiator of the ultraviolet or visible light cleavage line is used. Examples of the above photopolymerization initiators include benzophenone-based compounds such as benzyl, benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone; aromatic ketone compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, α-hydroxycyclohexylphenylketone; Acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, and anisoin methyl ether; aromatic ketal compounds such as benzyl dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; Thioxantone compounds such as thioxantone, 2-chlorothioxantone, 2-methylthioxantone, 2,4-dimethylthioxantone, isopropylthioxantone, 2,4-dichlorothioxantone, 2,4-diethylthioxantone, 2,4-diisopropylthioxantone, dodecylthioxantone; camperquinone; halogenated ketones; acylphosphine oxide; acylphosphonates, etc.

[0082] The amount of the photopolymerization initiator is 20 weight% or less when the total amount of the active energy beam curable adhesive composition is 100 weight%. The amount of the photopolymerization initiator is preferably 0.01 to 20 weight%, further preferably 0.05 to 10 weight%, and further preferably 0.1 to 5 weight%.

[0083] In addition, when the curable adhesive for a polarizing film according to the present invention is used as a visible light curable type containing a radical polymerizable compound as a curable component, it is particularly preferable to use a photopolymerization initiator that is highly sensitive to light of 380 nm or higher. A photopolymerization initiator that is highly sensitive to light of 380 nm or higher will be described later.

[0084] The above photopolymerization initiator is a compound represented by the following general formula (1);

[0085] [Chemical Formula 1]

[0086]

[0087] (during food, R 1 and R 2 represents -H, -CH2CH3, -iPr, or Cl, and R 1 and R 2 It is preferable to use alone (which may be the same or different) or to use in combination with a compound represented by general formula (1) and a photopolymerization initiator that is highly sensitive to light of 380 nm or more, as described below. When a compound represented by general formula (1) is used, the adhesion is superior compared to when a photopolymerization initiator that is highly sensitive to light of 380 nm or more is used alone. Among the compounds represented by general formula (1), R 1 and R 2 Diethylthioxanthone having -CH2CH3 is particularly preferred. The compositional ratio of the compound represented by general formula (1) in the adhesive composition is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 4 parts by weight, and even more preferably 0.9 to 3 parts by weight, based on 100 parts by weight of the total amount of curable component.

[0088] In addition, it is desirable to add a polymerization initiation aid as needed. Examples of polymerization initiation aids include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, etc., and ethyl 4-dimethylaminobenzoate is particularly preferred. When using a polymerization initiation aid, the amount added is typically 0 to 5 parts by weight, preferably 0 to 4 parts by weight, and most preferably 0 to 3 parts by weight, based on 100 parts by weight of the total amount of the curable component.

[0089] In addition, a known photopolymerization initiator may be used in combination as needed. Since the transparent protective film having UV absorption capacity does not transmit light of 380 nm or less, it is preferable to use a photopolymerization initiator that is highly sensitive to light of 380 nm or more as the photopolymerization initiator. Specifically, examples include 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(η5-2,4-cyclopentadiene-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl)-phenyl)titanium.

[0090] In particular, as a photopolymerization initiator, in addition to the photopolymerization initiator of general formula (1), a compound represented by the following general formula (2);

[0091] [Chemical Formula 2]

[0092]

[0093] (during food, R 3 , R 4 and R 5 represents -H, -CH3, -CH2CH3, -iPr, or Cl, and R 3, R 4 and R 5 It is preferable to use (which may be the same or different). As for the compound represented by general formula (2), 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (product name: IRGACURE 907, manufacturer: BASF), which is also a commercial product, can be preferably used. In addition, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (product name: IRGACURE 369, manufacturer: BASF) and 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinophenyl)phenyl]-1-butanone (product name: IRGACURE 379, manufacturer: BASF) are preferred because they have high sensitivity.

[0094] In the present invention, among the above photopolymerization initiators, it is preferable to use a photopolymerization initiator containing a hydroxyl group. When an active energy beam curable adhesive composition contains a photopolymerization initiator containing a hydroxyl group as a polymerization initiator, the solubility of the adhesive layer with a high concentration of component A on the polarizer side is increased, and the curability of the adhesive layer is increased. Examples of photopolymerization initiators having a hydroxyl group include 2-methyl-2-hydroxypropiophenone (trade name "DAROCUR 1173", manufactured by BASF), 1-hydroxycyclohexylphenylketone (trade name "IRGACURE 184", manufactured by BASF), 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (trade name "IRGACURE 2959", manufactured by BASF), and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one (trade name "IRGACURE 127", manufactured by BASF). In particular, 1-hydroxycyclohexylphenylketone is more preferred because it has particularly excellent solubility in an adhesive layer with a high concentration of component A.

[0095] The cationopolymerizable compounds used in cationopolymerizable adhesive compositions are classified into monofunctional cationopolymerizable compounds having one cationopolymerizable functional group in the molecule and polyfunctional cationopolymerizable compounds having two or more cationopolymerizable functional groups in the molecule. Since monofunctional cationopolymerizable compounds have relatively low liquid viscosity, their inclusion in a resin composition can reduce the liquid viscosity of the resin composition. Additionally, monofunctional cationopolymerizable compounds often possess functional groups that express various functions, so their inclusion in a cationopolymerizable adhesive composition can impart various functions to the cationopolymerizable adhesive composition and / or to the cured product of the cationopolymerizable adhesive composition. It is preferable to include polyfunctional cationopolymerizable compounds in the cationopolymerizable adhesive composition because they can crosslink the cured product of the cationopolymerizable adhesive composition in three dimensions. The ratio of a monofunctional cationic polymerizable compound to a polyfunctional cationic polymerizable compound is preferably mixed in a range of 10 to 1,000 parts by weight of the polyfunctional cationic polymerizable compound per 100 parts by weight of the monofunctional cationic polymerizable compound. Examples of cationic polymerizable functional groups include epoxy groups, oxetanyl groups, and vinyl ether groups. Examples of compounds having epoxy groups include aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds, and it is particularly preferable for the cationic polymerizable adhesive composition of the present invention to contain an alicyclic epoxy compound due to its excellent curability and adhesion properties.Examples of cycloaliphatic epoxy compounds include caprolactone modified products of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, trimethylcaprolactone modified products, and valerolactone modified products of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and specifically, celoxide 2021, celoxide 2021A, celoxide 2021P, celoxide 2081, celoxide 2083, and celoxide 2085 (all manufactured by Daicel Chemical Industry Co., Ltd.), Cyracure UVR-6105, Cyracure UVR-6107, Cyracure 30, and R-6110 (all manufactured by Dow Chemical Japan Co., Ltd.). It is desirable to include compounds having an oxetanyl group because they have the effect of improving the curability of the cationic polymerizable adhesive composition or lowering the liquid viscosity of the composition. Examples of compounds having an oxetanyl group include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene, 3-ethyl-3-(phenoxymethyl)oxetane, di[(3-ethyl-3-oxetanyl)methyl]ether, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, phenol novolak oxetane, etc., and Aaron Oxetane OXT-101, Aaron Oxetane OXT-121, Aaron Oxetane OXT-211, Aaron Oxetane OXT-221, Aaron Oxetane OXT-212 (all manufactured by Toa Synthetic Co., Ltd.) are commercially available. It is desirable to include a compound having a vinyl ether group because it has the effect of improving the curability of a cationic polymerizable adhesive composition or lowering the liquid viscosity of the composition. Examples of compounds having a vinyl ether group include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, triethylene glycol divinyl ether, cyclohexanedimethanol divinyl ether, cyclohexanedimethanol monovinyl ether, tricyclodecane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, pentaerythritol-type tetravinyl ether, etc.

[0096] The cation-polymerizable adhesive composition contains at least one compound selected from the compounds having epoxy groups, compounds having oxetanyl groups, and compounds having vinyl ether groups described above as a curable component, and since all of these are cured by cation polymerization, a photocation polymerization initiator is incorporated. This photocation polymerization initiator generates cation species or Lewis acids upon irradiation with active energy rays such as visible light, ultraviolet light, X-rays, or electron beams, and initiates the polymerization reaction of epoxy groups or oxetanyl groups. As the photocation polymerization initiator, the photogenerator described below is preferably used. In addition, when using a cationopolymerizable adhesive composition as a visible light curable, it is preferable to use a photocationopolymerization initiator that is highly sensitive to light of 380 nm or longer. However, since photocationopolymerization initiators are generally compounds that exhibit maximum absorption in the wavelength range around 300 nm or shorter than that, by incorporating a photosensitizer that exhibits maximum absorption in the wavelength range longer than that, specifically light longer than 380 nm, the generation of cation species or acids from the photocationopolymerization initiator can be promoted in response to light of wavelengths in this vicinity. Examples of photosensitizers include anthracene compounds, pyrene compounds, carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, photoreducing dyes, etc., and two or more of these may be used in a mixture. In particular, anthracene compounds are desirable because they have excellent photosensitizing effects, and specifically, Anthracure UVS-1331 and Anthracure UVS-1221 (manufactured by Kawasaki Chemical Co., Ltd.) can be cited. The content of the photosensitizer is preferably 0.1 wt% to 5 wt%, and more preferably 0.5 wt% to 3 wt%.

[0097] Optical film

[0098] In the present invention, the optical film provided by the polarizing film may be, for example, a transparent protective film or a phase difference film. In addition, surface modification treatment may be performed on the optical film as well as on the polarizer. Surface modification treatments may include corona treatment, plasma treatment, ytro treatment, etc., and corona treatment is particularly preferred.

[0099] As a material constituting a transparent protective film, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetylcellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (norbornene-based resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The transparent protective film may contain one or more types of any suitable additives. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, etc. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100 weight%, more preferably 50 to 99 weight%, even more preferably 60 to 98 weight%, and particularly preferably 70 to 97 weight%. If the content of the thermoplastic resin in the transparent protective film is 50 weight% or less, there is a concern that the high transparency inherent to the thermoplastic resin may not be sufficiently expressed.

[0100] In addition, regarding the material forming the transparent protective film, it is desirable that it has excellent transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy, and in particular, a moisture permeability of 150 g / m² 2 It is more desirable that it be / 24h or less, and 140 g / m²2 It is particularly desirable that it be / 24h or less, and 120 g / m² 2 It is more desirable to have less than 24h.

[0101] On the side of the transparent protective film where the polarizer is not adhered, a functional layer such as a hard coat layer, an anti-reflection layer, an anti-sticking layer, a diffusion layer, or an anti-glare layer may be formed. In addition, the functional layer such as the hard coat layer, the anti-reflection layer, the anti-sticking layer, the diffusion layer, or the anti-glare layer may be formed not only on the transparent protective film itself, but also separately as a distinct component from the transparent protective film.

[0102] The thickness of the transparent protective film can be appropriately determined, but generally, in terms of strength, workability such as handling, and thinness, it is about 1 to 500 μm, 1 to 300 μm is preferable, and 5 to 200 μm is more preferable. Furthermore, 10 to 200 μm is preferable, and 20 to 80 μm is preferable.

[0103] As the above transparent protective film, a phase difference film having a front phase difference of 40 nm or more and / or a thickness direction phase difference of 80 nm or more may be used. The front phase difference is typically controlled in the range of 40 to 200 nm, and the thickness direction phase difference is typically controlled in the range of 80 to 300 nm. When a phase difference film is used as a transparent protective film, thinning can be achieved because the phase difference film also functions as a transparent protective film.

[0104] Examples of phase difference films include birefringent films formed by uniaxial or biaxial stretching of polymer materials, alignment films of liquid crystal polymers, and films supporting an alignment layer of liquid crystal polymers. The thickness of the phase difference film is not particularly limited, but is generally about 20 to 150 μm.

[0105] As for the phase difference film, the following formulas (1) to (3):

[0106] 0.70 < Re

[0450] / Re

[0550] < 0.97 … (1)

[0107] 1.5×10 -3 <Δn < 6×10 -3 … (2)

[0108] 1.13 < NZ < 1.50 … (3)

[0109] (In the equation, Re

[0450] and Re

[0550] are, respectively, in-plane phase difference values ​​of the phase difference film measured with light of wavelengths of 450 nm and 550 nm at 23 ℃, Δn is the in-plane birefringence of nx - ny when the refractive indices of the phase difference film in the terminating axis direction and leading axis direction are nx and ny, respectively, and NZ is the ratio of the thickness direction birefringence nx - nz and the in-plane birefringence nx - ny when nz is the refractive index in the thickness direction of the phase difference film) An inverse wavelength dispersion type phase difference film satisfying this equation may be used.

[0110] A polarizing film related to the present invention can be manufactured, for example, by the following manufacturing method.

[0111] A method for manufacturing a polarizing film comprising a polarizer and an adhesive layer adjacent to a first optical film other than the polarizer, the method comprising a first bonding process for bonding the polarizer and the first optical film via a water-based adhesive layer, and a second bonding process for bonding the first optical film and a second optical film via the adhesive layer. It is preferable that the polarizer contains a metal component capable of becoming a divalent metal cation in water, particularly zinc. Additionally, it is preferable that the adhesive layer is formed by a cured layer of an active energy beam curable adhesive composition.

[0112] In addition, the polarizing film related to the present invention can also be manufactured, for example, by the following manufacturing method.

[0113] A method for manufacturing a polarizing film comprising a polarizer and an adhesive layer adjacent to the polarizer, wherein the method comprises a first bonding process in which the polarizer and a first optical film are bonded together via the adhesive layer. It is preferable that the polarizer contains a metal component capable of becoming a divalent metal cation in water, particularly zinc. Additionally, it is preferable that the adhesive layer is formed by a cured layer of an active energy beam curable adhesive composition.

[0114] In the above bonding process, various adhesive compositions are coated onto substrates such as polarizers or optical films, and the substrates such as polarizers or optical films are laminated to cure the adhesive composition. The method for coating the adhesive composition is appropriately selected according to the viscosity of the adhesive composition or the desired thickness, and examples include a reverse coater, a gravure coater (direct, reverse, or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, a rod coater, etc. Lamination of substrates such as polarizers or optical films can be performed by a roll laminator, etc.

[0115] The adhesive layer is formed by a cured layer of an adhesive composition, and it is particularly preferable that it is formed by a cured layer of an active energy beam curable adhesive composition, such as electron beam curable, ultraviolet beam curable, or visible light curable. In the bonding process, an active energy beam (electron beam, ultraviolet beam, visible light, etc.) is irradiated to cure the adhesive composition and form an adhesive layer. The direction of irradiation of the active energy beam (electron beam, ultraviolet beam, visible light, etc.) can be irradiated from any appropriate direction. When manufacturing a polarizing film related to the present invention using a continuous line, the line speed varies depending on the curing time of the adhesive composition, but is preferably 5 to 100 m / min, more preferably 10 to 50 m / min, and even more preferably 20 to 30 m / min. If the line speed is excessively low, productivity is insufficient or damage to the transparent protective film is excessively large, making it impossible to manufacture a polarizing film capable of withstanding durability tests, etc. If the line speed is excessively high, the curing of the curable resin composition becomes insufficient, and the desired adhesive properties may not be obtained.

[0116] The polarizing film of the present invention can be used as an optical film laminated with other optical layers in practical use. Although there are no particular limitations on the optical layers, one or more layers may be used, such as optical layers that are used in the formation of liquid crystal display devices, such as reflectors, transmissive plates, phase difference plates (including wavelength plates such as 1 / 2 or 1 / 4), and visual compensation films. In particular, a reflective polarizing film or a transmissive polarizing film formed by laminating a reflector or a transmissive reflector in addition to the polarizing film of the present invention, an elliptical polarizing film or a circular polarizing film formed by laminating a phase difference plate in addition to the polarizing film, a wide viewing angle polarizing film formed by laminating a visual compensation film in addition to the polarizing film, or a polarizing film formed by laminating a brightness enhancement film in addition to the polarizing film is preferred.

[0117] An optical film formed by laminating the above optical layer onto a polarizing film can be formed by sequentially laminating them separately during the manufacturing process of a liquid crystal display device, etc. However, forming an optical film by laminating them in advance offers the advantage of improving the manufacturing process of a liquid crystal display device, etc., due to superior quality stability and assembly work. Suitable adhesive means, such as an adhesive layer, may be used for lamination. When laminating the above polarizing film or other optical films, their optical axes can be arranged at an appropriate angle according to the desired phase difference characteristics, etc.

[0118] An adhesive layer may be formed on the aforementioned polarizing film or an optical film having at least one layer of polarizing film laminated thereon for bonding to other components such as liquid crystal cells. The adhesive forming the adhesive layer is not particularly limited, but, for example, an adhesive having a base polymer such as an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based or rubber-based polymer may be appropriately selected and used. In particular, it is preferable to use an adhesive that has excellent optical transparency, exhibits adhesive properties such as appropriate wettability, cohesiveness, and adhesion, and has excellent weather resistance and heat resistance, such as an acrylic adhesive.

[0119] The adhesive layer may be formed on one or both sides of a polarizing film or optical film as an overlapping layer of different compositions or types. In addition, when formed on both sides, the adhesive layer may be of different compositions, types, or thicknesses on the front and back of the polarizing film or optical film. The thickness of the adhesive layer can be appropriately determined according to the purpose of use or adhesive strength, and is generally 1 to 100 μm, preferably 5 to 30 μm, and particularly preferably 10 to 20 μm.

[0120] Regarding the exposed surface of the adhesive layer, a separator is temporarily attached and covered for the purpose of preventing contamination, etc., until it is provided for practical use. This prevents contact with the adhesive layer under normal handling conditions. As for the separator, except for the thickness conditions above, suitable thin sheets such as plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, or their laminates may be used, and if necessary, a suitable thin sheet such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide-based separator may be coated with a suitable release agent.

[0121] The polarizing film or optical film of the present invention can be preferably used for the formation of various devices, such as liquid crystal display devices. The formation of a liquid crystal display device can be carried out in accordance with conventional methods. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a polarizing film or optical film, and a lighting system as needed, and mounting a driving circuit, but in the present invention, there are no particular limitations except for the use of the polarizing film or optical film according to the present invention, and it can be carried out in accordance with conventional methods. Regarding the liquid crystal cell, any type such as a TN type, STN type, or π type can be used.

[0122] Suitable liquid crystal display devices can be formed, such as a liquid crystal display device in which a polarizing film or an optical film is placed on one or both sides of a liquid crystal cell, or a device in which a backlight or a reflector is used in a lighting system. In that case, the polarizing film or the optical film according to the present invention may be installed on one or both sides of the liquid crystal cell. When polarizing films or optical films are formed on both sides, they may be the same or different. In addition, when forming a liquid crystal display device, suitable components such as a diffuser, an anti-glare layer, an anti-reflective film, a protective plate, a prism array, a lens array sheet, a light diffuser, and a backlight may be placed in one or more layers at appropriate locations.

[0123] Examples

[0124] Embodiments of the present invention are described below, but the embodiments of the present invention are not limited to these.

[0125] <Manufacturing of Polarizers>

[0126] A polyvinyl alcohol film with an average degree of polymerization of 2700 and a thickness of 45 μm was stretched and conveyed between rolls with different peripheral speed ratios while dyeing. First, the polyvinyl alcohol film was immersed in a water bath at 30°C for 1 minute to swell it and stretched 1.2 times in the conveying direction (first stretching), and then, by immersing it in an aqueous solution of potassium iodide (0.03 wt%) and iodine (0.3 wt%) (liquid temperature 30°C) for 1 minute, it was stretched 3 times in the conveying direction while dyeing (second stretching). Next, this stretched film was stretched 6 times (based on the unstretched film) in the conveying direction while immersing it in an aqueous solution (bath) of boric acid (4 wt%), potassium iodide (5 wt%), and zinc sulfate (3.5 wt%) for 30 seconds (third stretching). Polarizer 1 was obtained by drying this stretched film. The thickness of polarizer 1 after drying was 18 μm. In addition, polarizer 2 was obtained according to the same method as polarizer 1, except that a polyvinyl alcohol film with a thickness of 30 μm was used. The thickness of polarizer 2 after drying was 12 μm.

[0127] Active Energy Line

[0128] As the active energy line, a visible light (gallium-filled metal halide lamp) irradiation device was used: Light HAMMER10 manufactured by Fusion UV Systems, Inc., with a V bulb, peak illuminance of 1600 mW / cm², and an integrated irradiation dose of 1000 mJ / cm² (wavelength 380 to 440 nm). In addition, the illuminance of the visible light was measured using a Sola-Check system manufactured by Solatell.

[0129] Method for Measuring Elemental Ratios in the Adhesive Layer

[0130] The elemental ratio of the adhesive layer provided by the polarizing film was measured by the following measurement method.

[0131] First, for either the polarizing film configuration (1) or the polarizing film configuration (2) below, an adhesive that does not constitute a polarizing film was applied to the surface of the second optical film and fixed to a metal support. Next, the adhesive and the first optical film or the second optical film were removed using an ultramicrotome to expose the adhesive layer to be measured. Next, an Ar-GCIB etching treatment was performed, and the exposed adhesive layer after the Ar-GCIB etching treatment was fixed by pressing it onto a sample plate with a Mo plate. After that, ESCA analysis was performed using a scanning X-ray photoelectron spectrometer (Quantum 2000 manufactured by ULVAC-PHI), and a wide-scan measurement was performed to conduct a qualitative analysis. In addition, a narrow-scan measurement was performed for carbon, oxygen, and nitrogen elements to calculate the elemental ratio (atomic%). From the obtained carbon element ratio (atomic%), oxygen element ratio (atomic%), and nitrogen element ratio (atomic%), (number of carbon atoms) / (number of oxygen atoms + number of nitrogen atoms) was calculated.

[0132] Panel Lighting Test

[0133] An automotive on-dash monitor (TKH703) manufactured by MAXWIN was disassembled to extract a liquid crystal panel. A polarizing film attached to the viewing side of this liquid crystal panel was peeled off, and instead, a polarizing film related to each example and comparative example manufactured was cut to the same size as the polarizing film peeled off from the liquid crystal panel. An adhesive layer (thickness 20 μm) was interposed, and the polarizing film was laminated so that the transmission axis was the same as that of the peeled polarizing film to obtain a liquid crystal panel.

[0134] As described above, the obtained liquid crystal panel was placed in an environment of 65°C and 95% humidity for 1000 hours and left in a room temperature and humidity environment for 24 hours. Afterwards, the liquid crystal panel was re-mounted in a disassembled monitor housing, and a black image was displayed to perform a visual inspection. As a result, if only a black screen was displayed, it was marked as ○, and if a white hazy display defect occurred in part of the screen, it was marked as ×.

[0135] Third Optical Film

[0136] The third optical film used in the following polarizing film composition (1) was manufactured by the following manufacturing method.

[0137] In an autoclave equipped with a stirrer, a cooling tube, a nitrogen inlet tube, and a thermometer, 48 parts by weight of hydroxypropylmethylcellulose (manufactured by Shin-Etsu Chemical, trade name Metorose 60SH-50), 15,601 parts by weight of distilled water, 8,161 parts by weight of diisopropyl fumarate, 240 parts by weight of 3-ethyl-3-oxetanylmethyl acrylate, and 45 parts by weight of t-butylperoxypivalate, a polymerization initiator, were added. After performing nitrogen bubbling for 1 hour, radical suspension polymerization was carried out by maintaining the mixture at 49°C for 24 hours while stirring. Subsequently, the mixture was cooled to room temperature, and the suspension containing the generated polymer particles was centrifuged. The obtained polymer was washed twice with distilled water and twice with methanol, and then dried under reduced pressure.

[0138] The obtained fumaric acid ester-based resin (a polymer having negative birefringence) was dissolved in a toluene-methyl ethyl ketone mixed solution (toluene / methyl ethyl ketone 50 wt% / 50 wt%) to make a 20% solution. In addition, 5 parts by weight of tributyl trimellitate as a plasticizer were added to 100 parts by weight of the fumaric acid ester-based resin to prepare a dope.

[0139] As a support film, a biaxially stretched film of polyester (polyethylene-terephthalate / isophthalate copolymer) (thickness 75 μm, width 1350 mm) was used. The tensile modulus (MD) of the support at 140 °C was 800 MPa.

[0140] A wound support film was set in the dispensing section of a film-making device, and the support film was unwound and conveyed downstream while heat treatment was performed in a heating furnace. The temperature of the heat treatment was adjusted by changing the atmosphere temperature inside the heating furnace. The heating time was adjusted by changing the conveying speed of the support. After heat treatment, the dope prepared in Synthesis Example A was applied onto the support so that the film thickness after drying was 6.3 μm, and dried at 140 ℃. The film after drying was wound together with the support as a laminate.

[0141] The above laminate was set in the output section of a stretching device, and while the laminate was output and conveyed to the downstream side, free-end uniaxial stretching was performed in a stretching furnace at a temperature of 140°C. After stretching, the support was peeled off from the laminate to obtain a phase difference film with a thickness of 6 μm. The stretching ratio was adjusted so that the in-plane retardation of the phase difference film after peeling off the support was 35 nm.

[0142] Example 1

[0143] As an adhesive, an aqueous solution containing a polyvinyl alcohol resin containing acetoacetyl groups (average degree of polymerization 1200, degree of saponification 98.5 mol%, degree of acetoacetylation 5 mol%) and methylolmelamine in a weight ratio of 3:1 was used. Using this adhesive, under temperature conditions of 30°C, a second optical film (a triacetylcellulose film with a hard coat layer formed thereon (manufactured by Fujifilm, product name "TG40UL", film thickness 40 μm)) and a first optical film (a cycloolefin film containing a phase difference (manufactured by Nippon Zeon, product name "ZT12", film thickness 17 μm)) were laminated on one side (viewing side) of polarizer 1 using a roll laminating machine, and then heated and dried in an oven to produce a laminated film having optical films laminated on both sides of the polarizer.

[0144] Next, using an MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, gravure roll count: 1000 pieces / inch, rotation speed 140% / line speed), an adhesive composition adjusted to the amount listed in Table 1 was coated to a thickness of 1 μm on the cycloolefin film side of the laminated film obtained above, including the phase difference, and laminated to the third optical film (film thickness 6 μm) using a roller machine. After that, visible light was irradiated from the third optical film side by an active energy beam irradiation device to cure the adhesive composition, and then hot air dried at 70°C for 3 minutes to obtain a polarizing film (a polarizing film of this composition is called "polarizing film composition (1)"). The thickness of the adhesive layer after drying was 1 μm. The lamination line speed was 25 m / min.

[0145] A sample for evaluating humidification durability was prepared by laminating a polarizing film related to Example 1, manufactured by interposing an adhesive layer (thickness 20 μm), onto one side of an alkali-free glass with a thickness of 0.7 mm. The sample was then placed in an environment of 65°C - 95% humidity and subjected to a humidification durability test for 1000 hours of exposure. For the sample for evaluating the humidification durability test after the humidification durability test, a polarizing film for Cross Nicol was laminated with an adhesive layer (thickness 20 μm) interposed on the other side of the alkali-free glass to which the polarizing film according to Example 1 was laminated, such that the transmission axes of each polarizing film were perpendicular to each other, and then placed on a backlight (the polarizing film according to Example 1 was on the upper surface), and the polarizing film according to Example 1 was observed visually to evaluate whether the occurrence of bright spots originating from foreign substances was evaluated.

[0146] After a humidification durability test involving 1,000 hours of exposure to an environment of 65 ℃ - 95% humidity, it was found that the polarizing film according to Example 1 did not have any bright spots originating from foreign substances extending more than 3 mm from the cross-section.

[0147] Example 2

[0148] As an adhesive, an aqueous solution containing polyvinyl alcohol resin containing acetoacetyl groups (average degree of polymerization 1200, degree of saponification 98.5 mol%, degree of acetoacetylation 5 mol%) and methylolmelamine in a weight ratio of 3:1 was used. Using this adhesive, under a temperature condition of 30°C, a second optical film (a triacetylcellulose film with a hard coat layer formed thereon (manufactured by Fujifilm, product name "TG40UL", film thickness 40 μm)) was laminated onto one side (the viewing side) of polarizer 1 using a roll laminating machine, and then heated and dried in an oven to produce a laminated film in which the optical film is laminated onto one side of the polarizer.

[0149] Next, using an MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, gravure roll count: 1000 pieces / inch, rotation speed 140% / line speed), an adhesive composition adjusted to the amount listed in Table 1 was coated to a thickness of 1 μm on the polarizer 1 side of the laminated film and laminated to the first optical film (cycloolefin film (manufactured by Nippon Zeon Co., Ltd., product name "ZF14", film thickness 13 μm)) using a roller machine. Afterward, visible light was irradiated from the cycloolefin film side using an active energy beam irradiation device to cure the adhesive composition, and then hot air dried at 70°C for 3 minutes to obtain a polarizing film (a polarizing film of this composition is called a "polarizing film composition (2)"). The thickness of the adhesive layer after drying was 1 μm. The lamination was performed at a line speed of 25 m / min.

[0150] For the polarizing film of Example 2 manufactured, a humidification durability test was performed by exposing it for 1,000 hours in an environment of 65°C - 95% humidity, just as in Example 1, and the presence or absence of bright spots originating from foreign substances was observed visually.

[0151] After a humidification durability test involving 1,000 hours of exposure to an environment of 65 ℃ - 95% humidity, it was found that the polarizing film according to Example 2 did not have any bright spots originating from foreign substances extending more than 3 mm from the cross-section.

[0152] Examples 3 to 6, Comparative Examples 1 to 6

[0153] Except for changing the composition of the polarizing film, the formulation of the adhesive composition, and the type of polarizer as listed in Table 1, the presence or absence of bright spots originating from foreign substances was observed by the same method as in Examples 1 and 2.

[0154]

[0155] The details of each component listed in Table 1 are as follows.

[0156] (Monofunctional radical polymerizable compound)

[0157] · Unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone (monomer component containing a hydroxyl group) (Trade name "Fraxel FA1DDM", manufactured by Daicel, Molecular weight 230.26, LogPow ; 1.06)

[0158] · Acryloylmorpholine (Trade name "ACMO", manufactured by Kojin, Molecular weight 141.17, LogPow ; -0.20)

[0159] · Diethylacrylamide (Trade name "DEAA", manufactured by KJ Chemicals, Molecular weight 127.18, LogPow ; 1.69)

[0160] · Lauryl acrylate (trade name "Light Acrylate LA", manufactured by Kyoeisha Chemical Co., Ltd., molecular weight 240.39, LogPow ; 6)

[0161] · Isostearyl acrylate (Trade name "ISTA", manufactured by Osaka Organic Chemical Industry Co., Ltd., molecular weight 324.5, LogPow ; 7.46)

[0162] · Dicyclofentanyl acrylate (Trade name "Pancryl FA-513AS", manufactured by Hitachi Chemical, Molecular weight 206.28, LogPow ; 2.58)

[0163] (Multifunctional radical polymerizable compound)

[0164] ·PEG400# Diacrylate (Trade name "Light Acrylate 9EG-A", manufactured by Kyoeisha Chemical Co., Ltd., Molecular weight 536.61, LogPow ; -0.1)

[0165] · Polypropylene glycol diacrylate (Trade name "Aronix M-220", manufactured by Toa Synthetic Co., Molecular weight 300.35, LogPow ; 1.68)

[0166] · 1,9-Nonandiol diacrylate (Trade name "Light Acrylate 1,9ND-A", manufactured by Kyoeisha Chemical Co., Ltd., molecular weight 268.35, LogPow ; 3.68)

[0167] · Dimethylol-tricyclodecane diacrylate (Trade name "Light Acrylate DCP-A", manufactured by Kyoeisha Chemical Co., Ltd., molecular weight 304.38, LogPow ; 3.05)

[0168] (Acrylic oligomer)

[0169] · 34 / 66 molar ratio copolymer oligomer of butyl acrylate and methacrylate (Trade name "ARUFON UP-1190", manufactured by Toa Synthetic Co., Ltd., molecular weight 1700, LogPow ; 1.95)

[0170] (Initiator)

[0171] ·2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (trade name "Omnirad 907", manufactured by IGM Resins BV, molecular weight 279.13, LogPow ; 2.09)

[0172] · Diethylthioxanthone (Trade name "KAYACURE DETX-S", manufactured by Nippon Hwayakusha, molecular weight 268.37, LogPow ; 5.12)

[0173] In Table 1, “(number of carbon atoms) / (number of oxygen atoms + number of nitrogen atoms)” means calculated based on the “method for measuring the elemental ratio of the adhesive layer” above, “average logPow” means “logPow representing the octanol / water partition coefficient based on the weighted average of the mole fraction of the monomer component contained in the adhesive composition,” and “distance from cross-section to foreign substance (mm)” means “distance from cross-section of the polarizing film to the spot originating from the identified foreign substance.” Explanation of the symbols

[0174] 10: Polarizing film 1 : Polarizer 2: Water-based adhesive layer 3, 4, 6: Optical film 5: Adhesive layer 7: Adhesive layer

Claims

Claim 1 A polarizing film comprising a polarizer and an adhesive layer adjacent to an optical film other than the polarizer, wherein the polarizer contains zinc, and the (number of carbon atoms) / (number of oxygen atoms + number of nitrogen atoms) based on the measurement of the elemental ratio of the adhesive layer is 2.5 or higher, and the adhesive layer contains oxalic acid, and the polarizing film is characterized by not having a bright spot originating from a foreign substance exceeding 3 mm from the cross-section after a humidification durability test of 1,000 hours of exposure to an environment of 65 ℃ - 95% humidity. Claim 2 delete Claim 3 delete Claim 4 A polarizing film according to claim 1, wherein the polarizing film comprises a polarizer and an optical film laminated with a water-based adhesive layer interposed on at least one surface of the polarizer, and an adhesive layer on the surface of the optical film opposite to the water-based adhesive layer. Claim 5 A polarizing film according to claim 1, wherein the adhesive layer is formed by a cured layer of an active energy beam curable adhesive composition. Claim 6 A polarizing film according to claim 1, wherein the adhesive layer is formed by a cured layer of the adhesive composition, and when the cured product obtained by curing the adhesive composition is immersed in pure water at 23°C for 24 hours, the bulk absorption rate is less than 10 weight%, expressed by the formula: {(M2-M1) / M1}×100 (%), where M1: weight of the cured product before immersion, M2: weight of the cured product after immersion. Claim 7 delete Claim 8 A polarizing film according to claim 1, wherein the adhesive layer is formed by a cured layer of the adhesive composition, and the logPow representing the octanol / water partition coefficient based on the weighted average of the mole fractions of the monomer components contained in the adhesive composition is 1.6 or higher. Claim 9 A polarizing film according to claim 8, wherein the adhesive composition contains 25 parts by weight or more of a monomer component having an alkyl group having 8 or more carbon atoms, when the total amount of the monomer component is 100 parts by weight. Claim 10 A polarizing film according to claim 8, wherein the adhesive composition contains 40 parts by weight or less of a monomer component having a hydroxyl group when the total amount of the monomer component is 100 parts by weight. Claim 11 An optical film characterized by having at least one polarizing film described in claim 1 laminated therein. Claim 12 An image display device characterized by using a polarizing film described in claim 1. Claim 13 An image display device characterized by the use of the optical film described in claim 11.

Images