Polarizing film, optical film, and image display device

Abstract

Provided is a polarizing film having a polarizer and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer, the polarizing film having no bright spot from foreign matter more than 3 mm from an end face after a humidity durability test in which the polarizing film is exposed to an environment of 65°C-95% humidity for 1000 hours. The polarizer preferably contains a metal component that can become a divalent metal cation in water, particularly zinc.

Description

Technical Field

[0001] This 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. This polarizing film can be used alone to form image display devices such as mobile phones, car navigation systems, computer monitors, and televisions, or it can be used as an optical film in which the polarizing film is laminated to form image display devices such as mobile phones, car navigation systems, computer monitors, and televisions. Background Technology

[0002] Liquid crystal displays (LCDs) are rapidly gaining market share in mobile phones, car navigation systems, computer monitors, and televisions. LCDs are devices that visualize the polarization state of liquid crystal switches, utilizing polarizing lenses based on their display principle. Especially in applications like televisions, there is an increasing demand for high brightness, high contrast, and wide viewing angles, leading to higher requirements for polarizing films such as high transmittance, high polarization degree, and high color reproduction.

[0003] As polarizers, those with high transmittance and high polarization are most commonly iodine-based polarizers, for example, those with a structure in which iodine is adsorbed onto polyvinyl alcohol (hereinafter also referred to as "PVA") and stretched. Generally, the polarizing film is a polarizing film on both sides of the polarizer, where a transparent protective film is bonded using a so-called aqueous adhesive made by dissolving a polyvinyl alcohol-based material in water (Patent Document 1 below). As the transparent protective film, a highly moisture-permeable material such as cellulose triacetate is used. When using the aforementioned aqueous adhesive (so-called wet lamination), a drying process is required after bonding the polarizer and the transparent protective film.

[0004] On the other hand, an active energy ray-curable adhesive has been proposed to replace the aforementioned water-based adhesive. When using an active energy ray-curable adhesive to manufacture polarizing films, the production rate of polarizing films can be improved because a drying process is not required. For example, a free radical polymerizable active energy ray-curable adhesive using N-substituted amide monomers as curing components has been proposed (Patent Document 2 below). The adhesive layer formed using the active energy ray-curable adhesive described in Patent Document 2 can sufficiently withstand water resistance tests, such as those evaluating whether there is discoloration or peeling after immersion in 60°C water for 6 hours. However, in recent years, polarizing films have been used not only in portable devices such as mobile phones but also in image display devices for automotive applications. In automotive applications, compared to portable device applications, durability tests under higher temperature and humidity conditions are required.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2001-296427

[0008] Patent Document 2: Japanese Patent Application Publication No. 2012-052000 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] As a durability test required for polarizing films used in automotive applications, there is, for example, a humidification durability test involving 1000 hours of exposure to an environment of 65°C and 95% humidity. Here, the inventors conducted a detailed study of the appearance of the polarizing film after this humidification durability test and discovered, particularly, white, hazy bright spots originating from foreign matter appearing at the ends of the polarizing film, which constitute a product defect from an appearance perspective. This phenomenon was observed for the first time after a durability test in a high-temperature and high-humidity environment, and further research is necessary to address this new problem.

[0011] The present invention was developed in view of the above-mentioned actual situation, and its purpose is to provide a polarizing film that suppresses the generation of bright spots from foreign matter even after a humidification durability test and has excellent appearance characteristics.

[0012] Problem Solving Methods

[0013] The above-mentioned problems can be solved by the following configuration. That is, the present invention relates to a polarizing film having a polarizer and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer, wherein the polarizing film, after being exposed to a humidification durability test in an environment of 65°C-95% humidity for 1000 hours, does not have any bright spots from foreign objects more than 3 mm away from the end face.

[0014] In the above-mentioned polarizing film, the polarizer preferably contains a metal component that can become a divalent metal cation in water.

[0015] In the above-mentioned polarizing film, zinc is the preferred metal component.

[0016] In the above-described polarizing film, the preferred polarizing film comprises:

[0017] polarizer,

[0018] An optical film laminated to at least one side of the polarizer via an aqueous adhesive layer, and

[0019] An adhesive layer is disposed on the side of the optical film opposite to the aqueous adhesive layer.

[0020] In the above-mentioned polarizing film, it is preferable that the adhesive layer is formed from the cured layer of an active energy ray curable adhesive composition.

[0021] In the aforementioned polarizing film, it is preferable that the adhesive layer is formed from a cured layer of the adhesive composition, and that the volumetric water absorption rate, expressed by the following formula, is less than 10% by weight when the cured product obtained by curing the adhesive composition is immersed in pure water at 23°C for 24 hours.

[0022] Formula: {(M2-M1) / M1}×100(%)

[0023] Where M1: weight of the cured material before impregnation, and M2: weight of the cured material after impregnation.

[0024] In the above-mentioned polarizing film, it is preferable that the ratio of (number of carbon atoms) / (number of oxygen atoms + number of nitrogen atoms) determined based on the elemental ratio of the above-mentioned adhesive layer is 2.5 or more.

[0025] In the above-mentioned polarizing film, it is preferable that the adhesive layer is formed from the cured layer of the adhesive composition, and the logPow, which is a weighted average of the molar fractions of the monomer components contained in the adhesive composition and represents the octanol / water partition coefficient, is 1.6 or more.

[0026] In the above-mentioned polarizing film, when the total amount of monomer components is preferably set to 100 parts by weight, the above-mentioned adhesive composition contains 25 parts by weight or more of monomer components having an alkyl group having 8 or more carbon atoms.

[0027] In the above-mentioned polarizing film, when the total amount of monomer components is preferably set to 100 parts by weight, the above-mentioned adhesive composition contains 40 parts by weight or less of monomer components having hydroxyl groups.

[0028] In addition, the present invention relates to an optical film and an image display device, wherein the optical film is at least laminated with one polarizing film as described in any of the above claims, and the image display device uses the polarizing film as described in any of the above claims and / or the optical film described above.

[0029] The effects of the invention

[0030] For polarizing films used in automotive applications, excellent appearance characteristics are required, for example, even after a humidification durability test of 1000 hours in an environment of 65°C-95% humidity. In the case of the polarizing film of this invention, after the aforementioned humidification durability test, there are no bright spots originating from foreign matter more than 3 mm from the end face; therefore, its appearance characteristics are excellent.

[0031] In particular, the polarizing film of the present invention exhibits excellent appearance characteristics even when a polarizing lens contains a metal component, especially zinc, that can become a divalent metal cation in water. The reason for this effect is not yet clear, but the following reasons can be presumed, for example.

[0032] For polarizing films comprising a polarizer and an adhesive layer adjacent to the polarizer or other optical films, during humidification durability testing, metallic components in the polarizer that can become divalent metal cations in water, particularly zinc, migrate from the polarizing film ends to the adhesive layer via vapor or condensation. Here, components other than those in the adhesive composition used as raw materials, such as oxalic acid, exist in the adhesive layer in an ionized state. However, as long as they do not bond with the metallic components to form oxalates, the oxalic acid is not detected as a foreign matter in the adhesive layer. However, during humidification durability testing, if specific metallic components from the polarizer are introduced into the adhesive layer from the ends, the ionized oxalic acid bonds with the metallic components, particularly forming oxalates at the ends of the adhesive layer. These oxalates appear as white bright spots and are detected as foreign matter. As a result, the appearance characteristics of the polarizing film deteriorate.

[0033] The polarizing film of the present invention comprises: a polarizer, and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer. After a humidification durability test of 1000 hours in an environment of 65°C to 95% humidity, the polarizing film exhibits no bright spots originating from foreign matter more than 3 mm from its end face. Particularly when the polarizer of the present invention comprises an adhesive layer designed such that the volume water absorption rate of the cured layer of the adhesive composition used as a raw material is less than 10% by weight, even if a specific metal component contained in the polarizer is mixed into the adhesive layer from the end, the bonding between the ionized oxalic acid and the metal component, and consequently the movement of oxalate from the end of the polarizing film inward, is suppressed. As a result, even after the humidification durability test, the appearance characteristics of the polarizing film are particularly improved.

[0034] In particular, the adhesive layer of the polarizing film of the present invention is formed from a cured layer of the adhesive composition. When (i) the ratio of (carbon atoms) / (oxygen atoms + nitrogen atoms) of the adhesive layer, as determined based on the elemental ratio of the adhesive layer, is 2.5 or more, or (ii) the logPow, representing the octanol / water partition coefficient, is 1.6 or more based on the weighted average of the mole fractions of the monomer components contained in the adhesive composition, the bonding between ionized oxalic acid and the metal component can be suppressed, thereby suppressing the movement of oxalate from the ends of the polarizing film inward. As a result, even after a humidification durability test, the appearance characteristics of the polarizing film are significantly improved. Attached Figure Description

[0035] Figure 1 This is an example of a cross-sectional schematic diagram of a polarizing film according to one embodiment of the present invention.

[0036] Figure 2 This is another example of a cross-sectional schematic diagram of a polarizing film according to one embodiment of the present invention.

[0037] Symbol Explanation

[0038] 10. Polarizing film

[0039] 1. Polarizing mirror

[0040] 2. Water-based adhesives

[0041] 3, 4, 6 Optical films

[0042] 5. Adhesive layer

[0043] 7 Adhesive layer Detailed Implementation

[0044] Figure 1 The diagram shows an example of a cross-sectional schematic of a polarizing film according to an embodiment of the present invention. The polarizing film 10 in this embodiment includes: a polarizer 1, and an adhesive layer 5 adjacent to a first optical film 4 other than the polarizer 1. More specifically, the polarizing film 10 includes: a polarizer 1, a first optical film (phase reversal film) 4 laminated on at least one side of the polarizer 1 via an aqueous adhesive layer 2, and an adhesive layer 5 disposed on the side of the first optical film (phase reversal film) 4 opposite to the aqueous adhesive layer 2. In particular, in this embodiment, the polarizing film 10 has a second optical film (transparent protective film) 3 laminated on one side of the polarizer 1 via the aqueous adhesive layer 2, a first optical film (phase reversal film) 4 laminated on the other side of the polarizer 1 via the aqueous adhesive layer 2, an adhesive layer 5 laminated on the first optical film (phase reversal film) 4, and a third optical film (phase reversal film) 6 laminated on the adhesive layer 5. The polarizing film 10 is further laminated with an adhesive layer 7 on the third optical film 6, and is laminated to the image display unit, etc. via the adhesive layer 7.

[0045] Figure 2 Another example of a cross-sectional schematic diagram of a polarizing film according to an embodiment of the present invention is shown. In this embodiment, the polarizing film 10 includes a polarizer 1 and an adhesive layer 5 adjacent to the polarizer 1. More specifically, in this embodiment, a second optical film (transparent protective film) 3 is laminated on one side of the polarizer 1 via an aqueous adhesive layer 2, and a first optical film (phase reversal film) 4 is laminated on the other side of the polarizer 1 via an adhesive layer 5. The polarizing film 10 further has an adhesive layer 7 laminated on the optical film 4, and is laminated to an image display unit, etc., via the adhesive layer 7.

[0046] exist Figure 1 and Figure 2In the polarizing film shown, the aqueous adhesive layer 2 can be suitably made of aqueous solutions of isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, waterborne polyesters, etc. (e.g., solid content concentration of 0.5–60% by weight). The thickness of the aqueous adhesive layer 2 is not particularly limited, but is typically around 0.01 μm to 0.5 μm after drying.

[0047] for Figure 1 and Figure 2 Regarding the polarizing film 10 shown, during the humidification durability test, the metallic components contained in the polarizer 1, particularly zinc, which can become divalent metal cations in water, migrate to the adhesive layer 5 at the end of the polarizing film 10 via vapor and condensation. Here, in the adhesive layer 5, components other than those contained in the adhesive composition used as raw materials, such as oxalic acid, exist in an ionized state. However, as long as they do not bond with the metallic components to form oxalates, the oxalic acid will not be detected as a foreign substance in the adhesive layer. However, if a specific metallic component contained in the polarizer 10 mixes into the adhesive layer 5 during the humidification durability test, the ionized oxalic acid bonds with the metallic components to form oxalates, appearing as white bright spots, and is detected as a foreign substance. Figure 1 and Figure 2 The polarizing film 10 shown, after being exposed to a humidification durability test for 1000 hours in an environment of 65°C-95% humidity, does not have any bright spots from foreign objects at a distance of more than 3 mm from the end face, more preferably more than 2 mm from the end face.

[0048] The various components of the polarizing film of the present invention will be described below. In the present invention, the polarizing film includes: a polarizing lens, and an adhesive layer adjacent to the polarizing lens or an optical film other than the polarizing lens.

[0049] <Polarizing Filter>

[0050] Polyvinyl alcohol (PVA) films, suitable for use in polarizers, are made from PVA or its derivatives. Examples of PVA derivatives include PVA formal and PVA acetal. Additionally, derivatives of PVA modified with olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid and their alkyl esters, and acrylamide, are also examples. Typically, PVAs with a degree of polymerization of approximately 1000–10000 and a degree of saponification of approximately 80–100 mol% are used.

[0051] Polyvinyl alcohol (PVA) films may contain additives such as plasticizers. Examples of plasticizers include polyols and their condensates, such as glycerol, diglycerol, triglyceride, ethylene glycol, propylene glycol, and polyethylene glycol. There are no particular restrictions on the amount of plasticizer used, but less than 20% by weight is suitable in PVA films.

[0052] When manufacturing a polarizing lens, a dyeing process is performed to stain the polyvinyl alcohol film with iodine, and a stretching process is performed to stretch the polyvinyl alcohol film in at least one direction. Generally, a series of processes including swelling, dyeing, crosslinking, stretching, washing and drying can be used to process the polyvinyl alcohol film.

[0053] The swelling process can be performed, for example, by immersing the polyvinyl alcohol (PVA) film in a swelling bath (water bath). This treatment allows the PVA film to swell while simultaneously cleaning the surface of the film from dirt and anti-blocking agents, thereby preventing uneven dyeing and other irregularities. Glycerin, potassium iodide, etc., can also be appropriately added to the swelling bath. The temperature of the swelling bath is typically around 20–60°C, and the immersion time is typically around 0.1–10 minutes.

[0054] The dyeing process can be carried out, for example, by immersing a polyvinyl alcohol film in an iodine solution. The iodine solution is typically an aqueous solution containing iodine and potassium iodide as a dissolving agent. The iodine concentration is typically about 0.01 to 1% by weight, preferably 0.02 to 0.5% by weight. The potassium iodide concentration is typically about 0.01 to 10% by weight, preferably 0.02 to 8% by weight.

[0055] In the iodine dyeing process, the temperature of the iodine solution is typically around 20–50°C, preferably 25–40°C. The immersion time is typically around 10–300 seconds, preferably in the range of 20–240 seconds. During iodine dyeing, the concentration of the iodine solution, the immersion temperature of the polyvinyl alcohol film in the iodine solution, and the immersion time are preferably adjusted in a manner that ensures the iodine and potassium content in the polyvinyl alcohol film reaches the above-mentioned ranges.

[0056] The crosslinking process can be carried out, for example, by immersing an iodine-dyed polyvinyl alcohol film in a treatment bath containing a crosslinking agent. Any suitable crosslinking agent can be used. Specific examples of crosslinking agents include boric acid, boron compounds such as borax, glyoxal, and glutaraldehyde. These crosslinking agents can be used alone or in combination. The solvent for the solution used in the crosslinking bath is usually water, but an organic solvent miscible with water can also be added appropriately. The crosslinking agent is usually used at a ratio of 1 to 10 parts by weight relative to 100 parts by weight of the solvent. Preferably, the solution of the crosslinking bath further contains auxiliaries such as iodides. The concentration of the auxiliaries is preferably 0.05 to 15% by weight, more preferably 0.5 to 8% by weight. The temperature of the crosslinking bath is usually around 20 to 70°C, preferably 40 to 60°C. The immersion time in the crosslinking bath is usually around 1 second to 15 minutes, preferably 5 seconds to 10 minutes.

[0057] The stretching process is the process of stretching a polyvinyl alcohol (PVA) film in at least one direction. Generally, the PVA film is stretched unidirectionally along the transport direction (length direction). There are no particular limitations on the stretching method; either wet stretching or dry stretching can be used. In the case of wet stretching, the PVA film is stretched to a given ratio in a processing bath. The solution for the stretching bath can be a solution obtained by adding compounds necessary for various processes to a solvent such as water or an organic solvent (e.g., ethanol). Examples of dry stretching methods include, for instance, roller stretching, heated roller stretching, and compression stretching. In the manufacture of polarizing mirrors, the stretching process can be performed at any stage. Specifically, it can be performed simultaneously with swelling, dyeing, and crosslinking, or at any time before or after these processes. Furthermore, stretching can be performed in multiple stages. The cumulative stretch ratio of the PVA film is typically 5 times or more, preferably around 5 to 7 times.

[0058] In this invention, the polarizer preferably contains a metal component that can become a divalent metal cation in water, more preferably magnesium, calcium, copper, or zinc, and particularly preferably zinc. By including zinc in the polarizer, the tendency for the transmittance of the polarizing film to decrease and for hue to deteriorate after heating tests can be suppressed. When the polarizer contains zinc, the zinc content in the polarizer is preferably 0.002 to 2% by weight, more preferably 0.01 to 1% by weight.

[0059] In this invention, it is preferable that the polarizer contains sulfate ions. By including sulfate ions in the polarizer, there is a tendency to suppress the decrease in the transmittance of the polarizing film after heating. When the polarizer contains sulfate ions, the sulfate ion content in the polarizer is preferably 0.02 to 0.45% by weight, more preferably 0.05 to 0.35% by weight, and even more preferably 0.1 to 0.25% by weight. It should be noted that the sulfate ion content in the polarizer can be calculated based on the sulfur atom content.

[0060] To ensure the polarizer contains zinc, it is preferable to perform a zinc impregnation treatment during the polarizer manufacturing process. Furthermore, to ensure the polarizer contains sulfate ions, it is preferable to perform a sulfate ion treatment during the polarizer manufacturing process.

[0061] Zinc impregnation treatment can be carried out, for example, by impregnating a polyvinyl alcohol membrane in a zinc salt solution. As the zinc salt, inorganic chlorine compounds such as aqueous solutions of zinc halides (e.g., zinc chloride, zinc iodide), zinc sulfate, and zinc acetate are preferred. Various zinc complexes can also be used in the zinc impregnation treatment. Furthermore, when the zinc salt solution is an aqueous solution containing potassium and iodide ions, such as potassium iodide, zinc ion impregnation is facilitated, and therefore preferred. The concentration of potassium iodide in the zinc salt solution is preferably set to about 0.5 to 10% by weight, and more preferably 1 to 8% by weight.

[0062] Sulfate ion treatment can be carried out, for example, by impregnating a polyvinyl alcohol membrane in an aqueous solution containing a metal sulfate salt. Preferably, the metal sulfate salt is one that readily separates into sulfate ions and metal ions in the treatment solution and is readily introduced into the polyvinyl alcohol membrane in an ionic state. Examples 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.

[0063] In the manufacture of the polarizer, the aforementioned zinc infiltration treatment and sulfate ion treatment can be performed at any stage. That is, the zinc infiltration treatment and sulfate ion treatment can be performed before or after the dyeing process. The zinc infiltration treatment and sulfate ion treatment can also be performed simultaneously. In this invention, it is preferable to use zinc sulfate as both the zinc salt and the metal sulfate salt, and to impregnate the polyvinyl alcohol film in a treatment bath containing zinc sulfate while simultaneously performing the zinc infiltration treatment and sulfate ion treatment. Alternatively, the zinc salt and the metal sulfate salt can be pre-existing in the dyeing solution, and the zinc infiltration treatment and / or sulfate ion treatment can be performed simultaneously with the dyeing process. The zinc infiltration treatment and sulfate ion treatment can also be performed simultaneously with stretching.

[0064] In zinc impregnation and sulfate ion treatment, the zinc and sulfate ion content in the polarizer are adjusted by modifying the concentrations of the zinc salt solution and the metal sulfate solution, the immersion temperature of the polyvinyl alcohol 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 solution is typically around 15–85°C, preferably 25–70°C. The immersion time is typically around 1–120 seconds, preferably in the range of 3–90 seconds. The concentrations of the zinc salt solution and the metal sulfate solution vary depending on the type of zinc salt and metal sulfate, typically ranging from 0.5–20% by weight, preferably 1–10% by weight, and more preferably 2–7% by weight. By setting the zinc salt concentration and the metal sulfate concentration within this range, the zinc and sulfate ion content in the polarizer can be set within the aforementioned preferred ranges.

[0065] The polyvinyl alcohol film (stretch film) that has undergone the above treatments is then subjected to a water washing process and a drying process, using the usual method.

[0066] The washing process is typically performed by immersing a polyvinyl alcohol (PVA) membrane in a water bath. The water bath can be pure water or an aqueous solution of an iodide (e.g., potassium iodide, sodium iodide, etc.). The concentration of the iodide aqueous solution is preferably 0.1–10% by weight. Additives such as zinc sulfate or zinc chloride may also be added to the iodide aqueous solution.

[0067] The washing temperature is typically 5–50°C, preferably 10–45°C, and more preferably 15–40°C. The immersion time is typically 10–300 seconds, preferably 20–240 seconds. The washing process can be performed only once or multiple times as needed. When performing multiple washing processes, the type and concentration of additives in the water bath used for each treatment can be adjusted appropriately.

[0068] The drying process of the polyvinyl alcohol film can be 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 3–20 μm.

[0069] In this invention, the obtained polarizer undergoes surface modification treatment. Examples of surface modification treatments include corona treatment, plasma treatment, and ITRO treatment, with corona treatment being particularly preferred. By performing corona treatment, reactive functional groups such as carbonyl and amino groups are generated on the surface of the polarizer, improving its adhesion to the durability-enhancing layer. Furthermore, surface impurities can be removed or surface unevenness can be reduced through ashing, thereby producing a polarizing film with excellent appearance properties.

[0070] In this invention, the polarizing film comprises: a polarizer, and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer. Figure 1 The polarizing film 10 shown includes an adhesive layer adjacent to the optical film (phase reversal film) 4 other than the polarizer 1. Additionally, in Figure 2 The polarizing film 10 shown includes an adhesive layer 5 adjacent to the polarizing mirror 1. This adhesive layer will be described below.

[0071] <Adhesive layer>

[0072] The adhesive layer is formed from the cured layer of the adhesive composition, and is particularly preferably formed from the cured layer of an adhesive composition that is curable by active energy rays such as electron beam curing, ultraviolet curing, and visible light curing. From the viewpoint of improving the appearance characteristics of the polarizing film, the thickness of the dried adhesive layer is preferably 0.01 μm to 5 μm, more preferably 0.01 μm to 3 μm. Active energy ray curable adhesive compositions can be divided into free radical polymerization curable adhesive compositions and cationic polymerization adhesive compositions. In this invention, active energy rays with wavelengths from 10 nm to less than 380 nm are referred to as ultraviolet light, and active energy rays with wavelengths from 380 nm to 800 nm are referred to as visible light.

[0073] As monomeric components constituting a free radical polymerizable adhesive composition, free radical polymerizable compounds can be listed. Examples of free radical polymerizable compounds include compounds having free radical polymerizable functional groups such as (meth)acryloyl or vinyl groups (carbon-carbon double bonds). These monomeric components can be either monofunctional free radical polymerizable compounds or polyfunctional free radical polymerizable compounds having two or more polymerizable functional groups. Furthermore, these free radical polymerizable compounds can be used alone or in combination of two or more. As these free radical polymerizable compounds, compounds having a (meth)acryloyl group are preferred, for example. It should be noted that in this invention, (meth)acryloyl refers to acryloyl and / or methacryloyl, and "(meth)" has the same meaning below.

[0074] Examples of monofunctional free radical polymerizable compounds include (meth)acrylamide derivatives having a (meth)acrylamide group. (meth)acrylamide derivatives are preferred in terms of ensuring adhesion to polarizers and various transparent protective films, as well as in terms of fast polymerization speed and excellent productivity. Specific examples of (meth)acrylamide derivatives include: N-methyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-butyl (meth)acrylamide, N-hexyl (meth)acrylamide, and other N-alkyl (meth)acrylamide derivatives; N-hydroxymethyl (meth)acrylamide, N-hydroxyethyl (meth)acrylamide, N-hydroxymethyl-N-propyl (meth)acrylamide, and other N-hydroxyalkyl (meth)acrylamide derivatives; aminomethyl (meth)acrylamide, aminoethyl (meth)acrylamide, and other N-aminoalkyl (meth)acrylamide derivatives; N-methoxymethylacrylamide, N-ethoxymethylacrylamide, and other N-alkoxy (meth)acrylamide derivatives; mercaptomethyl (meth)acrylamide, mercaptoethyl (meth)acrylamide, and other N-mercaptoalkyl (meth)acrylamide derivatives; and so on. In addition, heterocyclic (meth)acrylamide derivatives in which the nitrogen atom of the (meth)acrylamide group forms a heterocycle can be exemplified by, for example, N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine, etc.

[0075] Among the aforementioned (meth)acrylamide derivatives, N-hydroxyalkyl (meth)acrylamide derivatives are preferred from the perspective of adhesion to polarizing mirrors and various transparent protective films. In addition, various (meth)acrylic acid derivatives having (meth)acryloyloxy groups can be listed as monofunctional free radical polymerizable compounds. Specific examples include: methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, 2-methyl-2-nitropropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, n-pentyl methacrylate, tert-pentyl methacrylate, 3-pentyl methacrylate, 2,2-dimethylbutyl methacrylate, n-hexyl methacrylate, hexadecyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, 4-methyl-2-propylpentyl methacrylate, n-octadecyl methacrylate, and other alkyl esters of methacrylate (1-20 carbon atoms).

[0076] In addition, examples of the aforementioned (meth)acrylic acid derivatives include: cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, and other cycloalkyl (meth)acrylates; benzyl (meth)acrylate and other aralkyl (meth)acrylates; 2-isoborneol (meth)acrylate, 2-norborneol methyl (meth)acrylate, 2-norborneol methyl (meth)acrylate, 5-norbornen-2-yl methyl (meth)acrylate, 3-methyl-2-norborneol methyl (meth)acrylate, and (meth)acrylic acid... Polycyclic (meth)acrylates such as dicyclopentenyl ester, dicyclopentenoxyethyl ester, and dicyclopentyl ester; (meth)acrylates containing alkoxy or phenoxy groups such as 2-methoxyethyl ester, 2-ethoxyethyl ester, 2-methoxymethoxyethyl ester, 3-methoxybutyl ester, ethyl carbitol ester, phenoxyethyl ester, and alkylphenoxy polyethylene glycol ester; etc.

[0077] In addition, examples of the above-mentioned (meth)acrylic acid derivatives include: 2-hydroxyethyl (meth)acrylic acid, 2-hydroxypropyl (meth)acrylic acid, 3-hydroxypropyl (meth)acrylic acid, 2-hydroxybutyl (meth)acrylic acid, 4-hydroxybutyl (meth)acrylic acid, 6-hydroxyhexyl (meth)acrylic acid, 8-hydroxyoctyl (meth)acrylic acid, 10-hydroxydecyl (meth)acrylic acid, 12-hydroxylaurate (meth)acrylic acid, etc.; hydroxyalkyl (meth)acrylic acid esters such as [4-(hydroxymethyl)cyclohexyl]methyl acrylate, cyclohexanediol mono(meth)acrylic acid, 2-hydroxy-3-phenoxypropyl (meth)acrylic acid, etc.; glycidyl (meth)acrylic acid, 4-hydroxybutyl (meth)acrylic acid glycidyl ether, etc., containing epoxy groups; 2,2,2-trifluoroethyl (meth)acrylic acid, etc. Halogenated (meth)acrylates such as 2,2,2-trifluoroethyl ethyl ester, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, and 3-chloro-2-hydroxypropyl (meth)acrylate; alkylaminoalkyl (meth)acrylates such as dimethylaminoethyl (meth)acrylate; oxy-heterocyclic butyl (meth)acrylates such as 3-oxetane butyl methyl (meth)acrylate, 3-methyloxetane butyl methyl (meth)acrylate, 3-ethyloxetane butyl methyl (meth)acrylate, 3-butyloxetane butyl methyl (meth)acrylate, and 3-hexyloxetane butyl methyl (meth)acrylate; heterocyclic (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate and butyrolactone (meth)acrylate; neopentyl glycol (meth)acrylate adducts of hydroxypentanoic acid; and p-phenylphenol (meth)acrylate.

[0078] In addition, examples of monofunctional free radical polymerizable compounds include: (meth)acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and other carboxyl-containing monomers.

[0079] In addition, examples of monofunctional free radical polymerizable compounds include: N-vinylpyrrolidone, N-vinyl-ε-caprolactam, methylvinylpyrrolidone, and other lactam vinyl monomers; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazolium, and vinylpyrrole. Vinyl monomers containing nitrogen-containing heterocycles, such as azoles and vinylmorpholine.

[0080] Furthermore, as a monofunctional radical polymerizable compound, a radical polymerizable compound having an active methylene group can be used. A radical polymerizable compound having an active methylene group is a compound having an active double bond group such as a (meth)acryloyl group at the end or in the molecule, and having an active methylene group. Examples of active methylene groups include acetoacetyl, alkoxymalonyl, or cyanoacetyl. The preferred active methylene group is acetoacetyl. Specific examples of free radical polymerizable compounds containing an active methylene group include: 2-acetylacetoxyethyl methacrylate, 2-acetylacetoxyethyl propyl methacrylate, 2-acetylacetoxyethyl-1-methylethyl methacrylate, and other acetylacetoxyethyl alkyl methacrylates; 2-ethoxymalonyl ethyl methacrylate, 2-cyanoacetoxyethyl methacrylate, N-(2-cyanoacetoxyethyl)acrylamide, N-(2-propionylacetoxybutyl)acrylamide, N-(4-acetylacetoxyethylmethylbenzyl)acrylamide, N-(2-acetylacetylaminoethyl)acrylamide, etc. The preferred free radical polymerizable compound containing an active methylene group is an acetylacetoxyethyl alkyl methacrylate.

[0081] In addition, examples of multifunctional free radical polymerizable compounds having two or more polymerizable functional groups include: 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, tricyclodecanediethanol di(meth)acrylate, cyclic trimethylolpropane formal(meth)acrylate, and dimethylolpropane formal(meth)acrylate. Esterifications of methacrylic acid and polyols, such as alkyldiol 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 diglycerol tetra(meth)acrylate, as well as 9,9-bis[4-(2-(meth)acryloyloxyethoxy)phenyl]fluorene. Specific examples include ARONIX M-220 (manufactured by Toa Synthetic Co., Ltd.), LIGHT ACRYLATE 1,9ND-A (manufactured by Kyoeisha Chemical Co., Ltd.), LIGHT ACRYLATE DGE-4A (manufactured by Kyoeisha Chemical Co., Ltd.), LIGHT ACRYLATE DCP-A (manufactured by Kyoeisha Chemical Co., Ltd.), SR-531 (manufactured by Sartomer Co., Ltd.), and CD-536 (manufactured by Sartomer Co., Ltd.). In addition, as needed, various epoxy (meth)acrylates, urethane (meth)acrylates, polyester (meth)acrylates, and various (meth)acrylate monomers can be listed.

[0082] In this invention, the polarizing film comprises: a polarizing lens, and an adhesive layer adjacent to the polarizing lens or an optical film other than the polarizing lens, the adhesive layer being formed from a cured layer of an adhesive composition, wherein, when the cured product obtained by curing the adhesive composition is immersed in pure water at 23°C for 24 hours, the bulk water absorption rate, expressed by the following formula, is preferably less than 10% by weight.

[0083] Formula: {(M2-M1) / M1}×100(%)

[0084] Where M1: weight of the cured material before impregnation, and M2: weight of the cured material after impregnation.

[0085] According to this configuration, even when specific metallic components contained in the polarizer are mixed into the adhesive layer from the ends, the bonding between the ionized oxalic acid and the metallic components, and consequently the movement of oxalate from the ends of the polarizing film inward, is suppressed. As a result, even after a humidification durability test, the appearance characteristics of the polarizing film are particularly improved. The bulk water absorption rate is more preferably less than 8% by weight, and particularly preferably less than 6% by weight.

[0086] In this invention, the polarizing film comprises: a polarizer, and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer. The ratio of (carbon atoms) to (oxygen atoms + nitrogen atoms) of the adhesive layer, as determined by the elemental ratio of the adhesive layer, is preferably 2.5 or higher. It is generally believed that the bonding between ionized oxalic acid and the metal component, and consequently the movement of oxalate, occurs via water. Here, when the ratio of (carbon atoms) to (oxygen atoms + nitrogen atoms) of the adhesive layer, as determined by the elemental ratio of the adhesive layer, is 2.5 or higher, it is possible to suppress water intrusion into the adhesive layer from the ends. Particularly at the ends of the adhesive layer, it is possible to suppress the bonding between ionized oxalic acid and the metal component, and consequently, the movement of oxalate from the ends of the polarizing film inwards. As a result, even after a humidification durability test, the appearance characteristics of the polarizing film are significantly improved. The method for determining the elemental ratio of the adhesive layer will be described later.

[0087] Furthermore, in this invention, the polarizing film comprises: a polarizer, and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer. This adhesive layer is formed from 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 preferably 1.6 or higher. It is generally believed that the bonding between ionized oxalic acid and the metal component, and consequently the movement of oxalate, occurs via water. Here, when 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, it is possible to suppress water intrusion into the adhesive layer from the ends. Particularly at the ends of the adhesive layer, it is possible to suppress the bonding between ionized oxalic acid and the metal component, and consequently, the movement of oxalate from the ends of the polarizing film inwards. As a result, even after a humidification durability test, the appearance characteristics of the polarizing film are significantly improved.

[0088] The octanol / water partition coefficient (logPow) is an indicator of a substance's lipophilicity; it is the logarithm of the octanol / water partition coefficient. A high logPow indicates lipophilicity, meaning low water absorption. The logPow value can be measured (using the flask immersion method described in JIS-Z-7260) or calculated. In this specification, the logPow value calculated using the CambridgeSoft Chem Draw Ultra is used.

[0089] The following shows the logPow of major free radical polymerizable compounds. Examples include: hydroxyethyl acrylamide (trade name "HEAA", manufactured by Kojin Co., Ltd., LogPow: -0.56), diethylacrylamide (trade name "DEAA", manufactured by KJ Chemical Co., Ltd., LogPow: 1.69), unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone (trade name "PLACCEL FA1DDM", manufactured by Daicel Co., Ltd., LogPow: 1.06), N-vinylformamide (trade name "Beamset"), and others. 770”, manufactured by Arakawa Chemical Co., Ltd., LogPow: -0.25), Acryloylmorpholine (trade name "ACMO", manufactured by Kojin Co., Ltd., LogPow: -0.20), γ-butyrolactone acrylate (trade name "GBLA", manufactured by Osaka Organic Chemical Industry Co., Ltd., LogPow: 0.19), Acrylic acid dimer (trade name "β-CEA", manufactured by Daicel Co., Ltd., LogPow: 0.2), N-vinylpyrrolidone (trade name "NVP", manufactured by Nippon Shokubai Co., Ltd., LogPow: 0.24), Acetylacetoxyethyl 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 acrylate (trade name "Light Ester") G, Kyoei Chemical Co., Ltd., LogPow: 0.57), Dimethacrylamide (trade name "DMAA", manufactured by Kojin Co., Ltd., LogPow: 0.58), Tetrahydrofurfuryl acrylate polymer (trade name "Viscoat #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 Kyoei Chemical Co., Ltd., LogPow: -0.1), polypropylene glycol diacrylate (trade name “ARONIX M-220”, manufactured by Toa Synthetic Co., Ltd., LogPow: 1.68), dicyclopentenyl acrylate (trade name “FANCRYL 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), dicyclopentyl acrylate (trade name "FANCRYL FA-513AS", manufactured by Hitachi Chemical Co., Ltd., LogPow: 2.58), dimethyloltricyclodecane 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), neopentyl glycol acrylate adduct of hydroxypentanoic acid (trade name "LIGHT ACRYLATE HPP-A", manufactured by Kyoeisha Chemical Co., Ltd., LogPow: 3.35), 1,9-nonanediol diacrylate (trade name "LIGHT ACRYLATE 1.6HX-A"), 1,6-hex ... ACRYLATE 1, 9ND-A, manufactured by Kyoei Chemical Co., Ltd., LogPow: 3.68), o-phenylphenol EO modified acrylate (trade name "FANCRYL FA-301A", manufactured by Hitachi Chemical Co., Ltd., LogPow: 3.98), 2-ethylhexyloxetane (trade name "Aron Oxetane OXT-212", manufactured by Toa Synthetic Co., Ltd., LogPow: 4.24), bisphenol-A-diglycidyl ether (trade name "JER828", manufactured by Mitsubishi Chemical Co., Ltd., LogPow: 4.76), bisphenol A EO 6 molar modified diacrylate (trade name "FA-326A", manufactured by Hitachi Chemical Co., Ltd., LogPow: 4.84), bisphenol A EO4 molar modified diacrylate (trade name "FA-324A", manufactured by Hitachi Chemical Co., Ltd., LogPow: 5.15), bisphenol A PO2 molar modified diacrylate (trade name "FA-P320A", manufactured by Hitachi Chemical Co., Ltd., LogPow: 6.10), bisphenol A PO3 molar modified diacrylate (trade name "FA-P323A", manufactured by Hitachi Chemical Co., Ltd., LogPow: 6.26), bisphenol A PO4 molar modified diacrylate (trade name "FA-P324A", manufactured by Hitachi Chemical Co., Ltd., LogPow: 6.43), lauryl acrylate (trade name "LIGHTACRYLATE LA", manufactured by Kyoeisha Chemical Co., Ltd., LogPow: 6), isostearyl acrylate (trade name "ISTA"), manufactured by Osaka Organic Chemical Industry Co., Ltd.; LogPow: 7.46, etc.

[0090] The adhesive layer is formed from the cured layer of the adhesive composition. To ensure that the logPow, representing the octanol / water partition coefficient, is at least 1.6 based on the weighted average of the molar fractions of the monomer components contained in the adhesive composition, is at least 100 parts by weight, it is preferable that the total amount of monomer components is 100 parts by weight, and that it contains at least 25 parts by weight of monomer components having an alkyl group having 8 or more carbon atoms. Examples of monomer components having an alkyl group having 8 or more carbon atoms include dicyclopentyl acrylate (trade name "FANCRYL FA-513AS", manufactured by Hitachi Chemical Co., Ltd., LogPow: 2.58), lauryl acrylate (trade name "LIGHTACRYLATE LA", manufactured by Kyoeisha Chemical Co., Ltd., LogPow: 6), and isostearyl acrylate (trade name "ISTA", manufactured by Osaka Organic Chemical Industry Co., Ltd.; LogPow: 7.46), etc.

[0091] The adhesive layer is formed from the cured layer of the adhesive composition. To ensure that the logPow, representing the octanol / water partition coefficient, based on the weighted average of the molar fractions of the monomer components contained in the adhesive composition, is 1.6 or higher, it is preferable to set the content of the hydroxyl-containing monomer component to 40 parts by weight or less. It should be noted that examples of hydroxyl-containing monomer components include those described above.

[0092] Furthermore, in this invention, the polarizing film comprises: a polarizer, and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer. This adhesive layer is formed from a cured layer of the adhesive composition. When the total amount of monomer components is set to 100 parts by weight, the adhesive composition preferably contains 25 parts by weight or more, more preferably 30 parts by weight or more, of monomer components having two or more polymerizable functional groups. Even if oxalate is generated in this adhesive layer, the high hardness of the adhesive layer hinders the crystal growth of oxalate. As a result, the generation of foreign matter caused by oxalate is suppressed, and the appearance characteristics of the polarizing film are significantly improved.

[0093] Examples of monomeric components having two or more polymerizable functional groups include the aforementioned polyfunctional free radical polymeric compounds having two or more polymerizable functional groups. In particular, when the total amount of monomeric components is set to 100 parts by weight, and the adhesive composition contains 25 parts by weight or more of monomeric components having two or more polymerizable functional groups, it is preferable to set the content of monomeric components having hydroxyl groups to 40 parts by weight or less.

[0094] In this invention, the adhesive composition, which forms the adhesive layer of the polarizing film, may contain, in addition to a free radical polymerizable compound, an acrylic oligomer formed by polymerizing (meth)acrylic acid monomers. By including the acrylic oligomer in the adhesive composition, curing shrinkage during irradiation with active energy rays and subsequent curing can be reduced, thereby decreasing the interfacial stress between the adhesive layer and the adhered objects such as polarizers and optical films. As a result, the degradation of adhesion between the adhesive layer and the adhered objects can be suppressed.

[0095] Considering workability and uniformity during application, low viscosity is preferred for active energy radiation-cured adhesives; therefore, low viscosity is also preferred for acrylic oligomers polymerized from (meth)acrylic acid monomers. As a low-viscosity acrylic oligomer capable of preventing curing shrinkage of the adhesive layer, its weight-average molecular weight (Mw) is preferably 15,000 or less, more preferably 10,000 or less, and particularly preferably 5,000 or less. On the other hand, to sufficiently suppress curing shrinkage of the cured layer (adhesive layer), the weight-average molecular weight (Mw) of the acrylic oligomer is preferably 500 or more, more preferably 1,000 or more, and particularly preferably 1,500 or more.Examples of (meth)acrylic acid monomers constituting acrylic oligomers include: methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, 2-methyl-2-nitropropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, n-pentyl methacrylate, tert-pentyl methacrylate, 3-pentyl methacrylate, 2,2-dimethylbutyl methacrylate, n-hexyl methacrylate, etc. Cetyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, 4-methyl-2-propylpentyl methacrylate, n-octadecyl methacrylate, and other alkyl methacrylates (1-20 carbon atoms), as well as cycloalkyl methacrylates (e.g., cyclohexyl methacrylate, cyclopentyl methacrylate, etc.), aralkyl methacrylates (e.g., benzyl methacrylate, etc.), polycyclic methacrylates (e.g., 2-isobornyl methacrylate, 2-norbornyl methacrylate, etc.). Borneol methyl ester, 5-norbornen-2-yl methyl methacrylate, 3-methyl-2-norbornol methyl methacrylate, etc.; hydroxyl-containing (meth)acrylates (e.g., hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2,3-dihydroxypropyl methyl butyl methacrylate, etc.); alkoxy or phenoxy (meth)acrylates (2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, 2-methoxymethoxyethyl methacrylate, 3-methoxybutyl methacrylate). Ethyl carbitol acrylate (meth)acrylate, phenoxyethyl acrylate (meth)acrylate, etc.), epoxy-containing meth)acrylates (e.g., glycidyl acrylate (meth)acrylate, etc.), halogen-containing meth)acrylates (e.g., 2,2,2-trifluoroethyl meth)acrylate, 2,2,2-trifluoroethyl 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 can be used alone or in combination of two or more. 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 Ltd.

[0096] The amount of acrylic oligomers in the composition is typically preferred to be 15 parts by weight or less, relative to the total amount of monomer components in 100 parts by weight. Excessive content of acrylic oligomers in the composition can lead to a sharp decrease in the reaction rate when the composition is irradiated with active energy rays, resulting in poor curing. On the other hand, to sufficiently suppress curing shrinkage of the adhesive layer, it is preferable to contain 3 parts by weight or more of acrylic oligomers in the composition.

[0097] In the case of using free radical polymerizable compounds, the photopolymerization initiator can be appropriately selected based on the active energy of the radiation. In the case of curing by ultraviolet or visible light, a photopolymerization initiator that undergoes ultraviolet or visible light pyrolysis is used. Examples of such photopolymerization initiators include: benzoyl, benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, and other benzophenone compounds; aromatic ketone compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)one, α-hydroxy-α,α′-dimethylacetophenone, 2-methyl-2-hydroxyphenylacetone, α-hydroxycyclohexylphenyl ketone, and other aromatic ketone compounds; methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one, and other acetophenone compounds; benzoin methyl ether. Benzoin ethers, such as benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, and anisolein methyl ether; aromatic ketals, such as benzoin dimethyl ketal; aromatic sulfonyl chlorides, such as 2-naphthalenesulfonyl chloride; photoactive oximes, such as 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; thioxanthones, such as 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone; camphorquinone; haloketones; acylphosphine oxides; and acylphosphonates.

[0098] When the total amount of the active energy ray curable adhesive composition is set to 100% by weight, the amount of the above-mentioned photopolymerization initiator is 20% by weight or less. The amount of the photopolymerization initiator is preferably 0.01 to 20% by weight, more preferably 0.05 to 10% by weight, and even more preferably 0.1 to 5% by weight.

[0099] Furthermore, when using the polarizing film curable adhesive of the present invention in a visible light curable form containing a free radical polymerizable compound as a curing component, it is particularly preferable to use a photopolymerization initiator that is highly sensitive to light above 380 nm. The photopolymerization initiator that is highly sensitive to light above 380 nm will be described later.

[0100] As the above-mentioned photopolymerization initiator, it is preferred to use the compound shown in general formula (1) alone; or to use the compound shown in general formula (1) in combination with the photopolymerization initiator with high sensitivity to light above 380 nm described later.

[0101] [Chemical Formula 1]

[0102]

[0103] (where R is in the formula) 1 and R 2 Represents -H, -CH2CH3, -iPr, or Cl, R 1 and R 2 (These may be the same or different). When using the compound shown in general formula (1), the adhesion is superior compared to using a photopolymerization initiator with high sensitivity to light above 380 nm alone. Among the compounds shown in general formula (1), R is particularly preferred. 1 and R 2 The compound is diethylthioxanthone with the formula -CH2CH3. The composition 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, relative to 100 parts by weight of the total curing component.

[0104] In addition, it is preferable to add a polymerization initiator as needed. Examples of polymerization initiators include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, and isoamyl 4-dimethylaminobenzoate, with ethyl 4-dimethylaminobenzoate being particularly preferred. When using a polymerization initiator, its amount added relative to 100 parts by weight of the total curing component is typically 0 to 5 parts by weight, preferably 0 to 4 parts by weight, and most preferably 0 to 3 parts by weight.

[0105] In addition, known photopolymerization initiators can be used in combination as needed. Since transparent protective films with UV absorption capabilities do not transmit light below 380 nm, photopolymerization initiators that are highly sensitive to light above 380 nm are preferred. Examples include: 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropane-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholino)phenyl]-1-butanone, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and bis(η5-2,4-cyclopentadien-1-yl)bis(2,6-difluoro-3-(1H-pyrrole-1-yl)phenyl)titanium, etc.

[0106] In particular, in addition to photopolymerization initiators of general formula (1), compounds represented by the following general formula (2) are preferably further used as photopolymerization initiators.

[0107] [Chemical Formula 2]

[0108]

[0109] (where R is in the formula) 3 R 4 and R 5 Represents H, -CH3, -CH2CH3, -iPr, or Cl, R 3 R 4 and R 5 (These may be the same or different). As the compound represented by general formula (2), 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropane-1-one (trade name: IRGACURE 907, manufacturer: BASF), which is commercially available, can be used appropriately. In addition, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone (trade name: IRGACURE 369, manufacturer: BASF) and 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholino)phenyl]-1-butanone (trade name: IRGACURE 379, manufacturer: BASF) are preferred due to their high sensitivity.

[0110] In this invention, a hydroxyl-containing photopolymerization initiator is preferably used among the aforementioned photopolymerization initiators. When the active energy ray-curable adhesive composition contains a hydroxyl-containing photopolymerization initiator as a polymerization initiator, the solubility of the adhesive layer with a high concentration of component A on the polarizer side is improved, and the curing properties of the adhesive layer are improved. Examples of photopolymerization initiators containing hydroxyl groups include: 2-methyl-2-hydroxyphenylacetone (trade name "DAROCUR1173", manufactured by BASF), 1-hydroxycyclohexylphenyl ketone (trade name "IRGACURE184", manufactured by BASF), 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one (trade name "IRGACURE2959", manufactured by BASF), and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propanoyl)-benzyl]phenyl}-2-methyl-propane-1-one (trade name "IRGACURE127", manufactured by BASF). 1-hydroxycyclohexylphenyl ketone is particularly preferred due to its excellent solubility in adhesive layers with high concentrations of component A.

[0111] Cationic polymeric compounds used in cationic polymeric adhesive compositions can be classified into monofunctional cationic polymeric compounds having one cationic polymeric functional group within the molecule, and polyfunctional cationic polymeric compounds having two or more cationic polymeric functional groups within the molecule. Since monofunctional cationic polymeric compounds have lower liquid viscosity, the liquid viscosity of the resin composition can be reduced by including a monofunctional cationic polymeric compound in the resin composition. Furthermore, monofunctional cationic polymeric compounds generally possess functional groups exhibiting various functions; by including a monofunctional cationic polymeric compound in the cationic polymeric adhesive composition, various functions can be exhibited in the cationic polymeric adhesive composition and / or the cured cationic polymeric adhesive composition. Polyfunctional cationic polymeric compounds are preferred because they can cause three-dimensional crosslinking in the cured cationic polymeric adhesive composition. Regarding the ratio of monofunctional cationic polymeric compounds to polyfunctional cationic polymeric compounds, it is preferable to mix the polyfunctional cationic polymeric compounds in the range of 10 to 1000 parts by weight relative to 100 parts by weight of the monofunctional cationic polymeric compound. Examples of cationic polymeric functional groups include epoxy groups, oxetyl groups, and vinyl ether groups. Examples of compounds containing epoxy groups include aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds. Due to their excellent curability and adhesive properties, alicyclic epoxy compounds are particularly preferred as the cationic polymeric adhesive composition of the present invention. Examples of alicyclic epoxy compounds include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, caprolactone-modified versions of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, trimethylcaprolactone-modified versions, and valproic acid-modified versions. Specific examples include CELLOXIDE 2021, CELLOXIDE 2021A, CELLOXIDE 2021P, CELLOXIDE2081, CELLOXIDE2083, CELLOXIDE 2085 (all manufactured by Celero Chemical Industry Co., Ltd.), Cyracure UVR-6105, Cyracure UVR-6107, Cyracure 30, and R-6110 (all manufactured by Dow Chemical Japan Ltd.). Compounds containing oxocyclic butyl groups are preferred because they improve the curability of cationic polymeric curable adhesive compositions and reduce the liquid viscosity of the composition.Examples of compounds containing oxetane groups include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis[(3-ethyl-3-oxetane)methoxymethyl]benzene, 3-ethyl-3-(phenoxymethyl)oxetane, di[(3-ethyl-3-oxetane)methyl] ether, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, and phenolic varnish oxetane. Commercially available examples include ARON OXETANE OXT-101, ARON OXETANE OXT-121, ARON OXETANE OXT-211, ARON OXETANE OXT-221, and ARON OXETANE OXT-212 (all manufactured by Toa Synthetic Co., Ltd.). Compounds containing vinyl ether groups are preferred because they improve the curability of cationic polymerizable adhesive compositions and reduce the liquid viscosity of the composition. Examples of compounds containing 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, cyclohexanediethanol divinyl ether, cyclohexanediethanol monovinyl ether, tricyclodecane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, and pentaerythritol-type tetravinyl ether.

[0112] The cationic polymerizable adhesive composition contains at least one compound selected from the above-described compounds having epoxy groups, oxetyl groups, and vinyl ether groups as a curing component. These are all substances that are cured by cationic polymerization, and therefore a photocationic polymerization initiator is incorporated. This photocationic polymerization initiator generates cationic species or Lewis acids upon irradiation with active energy rays such as visible light, ultraviolet light, X-rays, and electron beams, thereby initiating the polymerization reaction of epoxy groups and oxetyl groups. As a photocationic polymerization initiator, a photoacid generator described later can be suitably used. Furthermore, when using the cationic polymerizable adhesive composition as a visible light curable material, a photocationic polymerization initiator with high sensitivity to light above 380 nm is particularly preferred. However, photocationic polymerization initiators are compounds that typically exhibit maximum absorption in the wavelength region around 300 nm or shorter than 300 nm. Therefore, by incorporating a photosensitizer that exhibits maximum absorption in a longer wavelength region, specifically longer than 380 nm, light at nearby wavelengths can be sensed, promoting the generation of cationic species or acids from the photocationic polymerization initiator. Examples of photosensitizers include anthracene compounds, pyrene compounds, carbonyl compounds, organosulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreducing pigments. Two or more of these can also be used in combination. Anthracene compounds are particularly preferred due to their excellent photosensitizing effect; specific examples include Anthracure UVS-1331 and Anthracure UVS-1221 (manufactured by Kawasaki Chemical Co., Ltd.). The photosensitizer content is preferably 0.1% to 5% by weight, more preferably 0.5% to 3% by weight.

[0113] <Optical film>

[0114] In this invention, the optical film included in the polarizing film can be, for example, a transparent protective film or a phase retardation film. It should be noted that not only the polarizer but also the optical film can undergo surface modification treatment. Examples of surface modification treatments include corona treatment, plasma treatment, and ITRO treatment, with corona treatment being particularly preferred.

[0115] As materials for transparent protective films, thermoplastic resins with excellent transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy can be used. Specific examples of such thermoplastic resins include cellulose resins such as cellulose triacetate, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The transparent protective film may contain one or more suitable additives. Examples of additives include: ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, and colorants. The content of the aforementioned thermoplastic resin in the transparent protective film is preferably 50–100% by weight, more preferably 50–99% by weight, further preferably 60–98% by weight, and particularly preferably 70–97% by weight. When the content of the aforementioned thermoplastic resin in the transparent protective film is less than 50% by weight, there are concerns that the high transparency inherent in the thermoplastic resin may not be fully expressed.

[0116] Furthermore, as the material for forming the transparent protective film, materials with excellent transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy are preferred, especially those with a moisture permeability of 150 g / m². 2 / less than 24h, especially preferred is 140g / m 2 / less than 24h, further preferably 120g / m 2 / less than 24 hours.

[0117] Functional layers such as a hard coating, anti-reflective layer, anti-adhesion layer, diffusion layer, or anti-glare layer can be applied to the side of the transparent protective film that is not bonded to the polarizer. It should be noted that the aforementioned functional layers such as the hard coating, anti-reflective layer, anti-adhesion layer, diffusion layer, and anti-glare layer can be used not only to protect the transparent protective film itself, but also to be separately applied as layers different from the transparent protective film.

[0118] The thickness of the transparent protective film can be appropriately determined. Generally, considering factors such as strength, processability, and thinness, it is approximately 1–500 μm, preferably 1–300 μm, and more preferably 5–200 μm. Further preferably, it is 10–200 μm, and more preferably 20–80 μm.

[0119] As the aforementioned transparent protective film, a phase retardation film with a frontal phase difference of 40 nm or more and / or a thickness direction phase difference of 80 nm or more can be used. Typically, the frontal phase difference is controlled within the range of 40–200 nm, and the thickness direction phase difference is typically controlled within the range of 80–300 nm. When a phase retardation film is used as a transparent protective film, it also functions as a transparent protective film, thus enabling thinner designs.

[0120] Examples of phase retardation films include: birefringent films formed by unidirectional or bidirectional stretching of polymer raw materials; alignment films of liquid crystal polymers; and phase retardation films formed by using a film to support an alignment layer of liquid crystal polymers. The thickness of phase retardation films is not particularly limited, generally ranging from 20 to 150 μm.

[0121] As a phase retardation film, an inverse wavelength dispersion type phase retardation film that satisfies the following equations (1) to (3) can be used:

[0122] 0.70<Re

[450] / Re

[550] <0.97···(1)

[0123] 1.5×10 -3 <Δn<6×10 -3 ···(2)

[0124] 1.13 < NZ < 1.50 ···(3)

[0125] (In the formula, Re

[450] and Re

[550] are the in-plane phase difference values ​​of the phase difference film measured at 23℃ using light with wavelengths of 450nm and 550nm, respectively. Δn is nx-ny, i.e., in-plane birefringence, when the refractive indices of the slow axis and fast axis of the phase difference film are set to nx and ny, respectively. NZ is the ratio of nx-nz to nx-ny when nz is set as the refractive index of the thickness direction of the phase difference film, where nx-nz is the thickness direction birefringence and nx-ny is the in-plane birefringence).

[0126] The polarizing film of the present invention can be manufactured, for example, by the following manufacturing method.

[0127] A method for manufacturing a polarizing film, the 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 step of bonding the polarizer and the first optical film together via an aqueous adhesive layer; and a second bonding step of bonding the first optical film and a second optical film together via the adhesive layer. The polarizer preferably contains a metal component capable of becoming a divalent metal cation in water, particularly zinc. Furthermore, the adhesive layer is preferably formed by curing a cured layer of an active energy radiation-curable adhesive composition.

[0128] Alternatively, the polarizing film of the present invention can also be manufactured by the following manufacturing method.

[0129] A method for manufacturing a polarizing film, the polarizing film comprising: a polarizer and an adhesive layer adjacent to the polarizer, the method comprising: a first bonding step of bonding the polarizer and a first optical film together via the adhesive layer. The polarizer preferably contains a metal component capable of becoming a divalent metal cation in water, particularly zinc. Furthermore, the adhesive layer is preferably formed by curing a cured layer of an active energy radiation-curable adhesive composition.

[0130] In the above bonding process, various adhesive compositions are applied to the substrates such as polarizers and optical films, the substrates are then bonded together, and the adhesive composition is cured. Methods for applying the adhesive composition can be selected appropriately based on the viscosity and target thickness of the adhesive composition; examples include: reverse coaters, gravure coaters (direct, reverse, or offset), rod reverse coaters, roller coaters, die coaters, wire-wound rod coaters, and bar coaters. The bonding of the substrates such as polarizers and optical films can be performed using roller laminators, etc.

[0131] The aforementioned adhesive layer is formed from a cured layer of the adhesive composition, and is particularly preferably formed from a cured layer of an adhesive composition cured by active energy rays such as electron beam curing, ultraviolet curing, or visible light curing. In the bonding process, the adhesive composition is cured by irradiation with active energy rays (electron beam, ultraviolet light, visible light, etc.), thereby forming the adhesive layer. The irradiation direction of the active energy rays (electron beam, ultraviolet light, visible light, etc.) can be any suitable direction. When manufacturing the polarizing film of the present invention on a continuous production line, the linear velocity varies depending on the curing time of the adhesive composition, preferably 5 to 100 m / min, more preferably 10 to 50 m / min, and even more preferably 20 to 30 m / min. If the linear velocity is too low, productivity is insufficient, or excessive damage is caused to the transparent protective film, making it impossible to produce a polarizing film that can withstand durability tests, etc. If the linear velocity is too high, sometimes the curing of the curable resin composition becomes insufficient, and the target adhesion is not obtained.

[0132] In practical applications, the polarizing film of the present invention can be fabricated into an optical film laminated with other optical layers. There are no particular limitations on the optical layer; for example, one or more layers of reflective plates, semi-transparent plates, retardation plates (including half-wave plates, quarter-wave plates, etc.), viewing angle compensation films, and other optical layers sometimes used in the formation of liquid crystal display devices can be used. Particularly preferred are reflective polarizing films or semi-transparent polarizing films formed by further laminating reflective plates or semi-transparent reflective plates onto the polarizing film of the present invention; elliptical polarizing films or circular polarizing films formed by further laminating retardation plates onto the polarizing film; wide-viewing-angle polarizing films formed by further laminating viewing angle compensation films onto the polarizing film; and polarizing films formed by further laminating brightness-enhancing films onto the polarizing film.

[0133] The optical film formed by stacking the aforementioned optical layers on a polarizing film can also be formed by sequentially stacking them one by one during the manufacturing process of liquid crystal display devices, etc. However, pre-stacking optical films has advantages such as superior quality stability and assembly operation, thereby improving the manufacturing process of liquid crystal display devices, etc. Suitable bonding methods such as adhesive layers can be used during the stacking. When bonding the aforementioned polarizing film and other optical films, their optical axes can be configured at suitable angles according to the target phase difference characteristics, etc.

[0134] An adhesive layer for bonding with other components such as liquid crystal cells can also be provided on the aforementioned polarizing film or optical film having at least one layer of polarizing film. There are no particular limitations on the adhesive forming the adhesive layer; adhesives using polymers such as acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyethers, fluorinated polymers, and rubber polymers as the base polymer can be suitably selected. Acrylic adhesives, which exhibit excellent optical transparency and moderate wetting, cohesiveness, and adhesion properties, as well as excellent weather resistance and heat resistance, are particularly preferred.

[0135] The adhesive layer can be provided on one or both sides of the polarizing film or optical film in the form of a laminate of layers with different compositions or types. Furthermore, when provided on both sides, adhesive layers with different compositions, types, and thicknesses can be formed on the front and back surfaces of the polarizing film or optical film. The thickness of the adhesive layer can be appropriately determined according to the intended use, adhesion strength, etc., and is typically 1–100 μm, preferably 5–30 μm, and particularly preferably 10–20 μm.

[0136] The exposed surface of the adhesive layer is temporarily covered by an adhesive diaphragm until it is put into actual use to prevent contamination. This prevents contact with the adhesive layer under normal handling conditions. As the diaphragm, suitable diaphragms as previously specified can be used, in addition to the thickness requirements described above, by coating suitable thin materials such as plastic films, rubber sheets, paper, cloth, nonwoven fabrics, meshes, foam sheets, metal foils, and their laminates with suitable release agents such as silicone, long-chain alkyl, fluorine, and molybdenum sulfide as needed.

[0137] The polarizing film or optical film of the present invention can be preferably used in the formation of various devices such as liquid crystal display devices. The formation of a liquid crystal display device can be performed in a conventional manner. That is, a liquid crystal display device is typically formed by appropriately assembling a liquid crystal cell with a polarizing film or optical film, and components such as an illumination system used as needed, and incorporating a driving circuit. In the present invention, there are no particular limitations except for the use of the polarizing film or optical film of the present invention, and conventional methods can be followed. Regarding the liquid crystal cell, any type of liquid crystal cell, such as TN type, STN type, or π type, can be used.

[0138] Suitable liquid crystal display devices can be formed, such as liquid crystal display devices in which polarizing films or optical films are disposed on one or both sides of the liquid crystal cell, and liquid crystal display devices that use backlights or reflectors in the lighting system. In this case, the polarizing film or optical film of the present invention can be disposed on one or both sides of the liquid crystal cell. When polarizing films or optical films are disposed on both sides, they can be the same or different. Furthermore, during the formation of the liquid crystal display device, one or more suitable components such as diffuser plates, anti-glare layers, anti-reflective films, protective plates, prism arrays, lens array sheets, light diffuser plates, and backlights can be disposed at appropriate positions.

[0139] Example

[0140] The following describes embodiments of the present invention, but the implementation of the present invention is not limited to these.

[0141] <Manufacturing of Polarizing Lenses>

[0142] A polyvinyl alcohol (PVA) film with an average degree of polymerization of 2700 and a thickness of 45 μm was subjected to stretching and conveying while being dyed on rollers at different circumferential speeds. First, the PVA film was immersed in a water bath at 30°C for 1 minute to swell, and then stretched 1.2 times in the conveying direction (first stretch). Next, it was immersed in an aqueous solution of potassium iodide (0.03 wt%) and iodine (0.3 wt%) (liquid temperature 30°C) for 1 minute, and then stretched 3 times in the conveying direction while being dyed (unstretched film reference) (second stretch). Then, the stretched film was immersed in an aqueous solution of boric acid (4 wt%), potassium iodide (5 wt%), and zinc sulfate (3.5 wt%) (bath solution) for 30 seconds, and stretched 6 times in the conveying direction (unstretched film reference) (third stretch). The stretched film was then dried to obtain polarizer 1. The thickness of polarizer 1 after drying was 18 μm. In addition, a 30 μm thick polyvinyl alcohol film was used, and polarizer 2 was obtained using the same manufacturing method as polarizer 1. The thickness of polarizer 2 after drying is 12 μm.

[0143] <Active Energy Rays>

[0144] As an active energy beam, a visible light (gallium-encased metal halide lamp) irradiation device was used: FusionUV Systems, Inc., Light HAMMER10, valve: V valve, peak illuminance: 1600 mW / cm². 2 Cumulative radiation dose 1000 mJ / cm 2 (Wavelength 380–440 nm). It should be noted that the illuminance of visible light was measured using the Sola-Check system manufactured by Solatell.

[0145] <Method for determining the elemental ratio of adhesive layers>

[0146] The elemental ratio of the adhesive layer in the polarizing film was determined by the following measurement method.

[0147] First, for both polarizing film configurations (1) and (2), an adhesive that does not constitute a polarizing film is applied to the surface of the second optical film and fixed to a metal support stage. Next, the adhesive and either the first or second optical film are removed using an ultramicrotome, exposing the adhesive layer to be measured. Then, Ar-GCIB etching is performed, and the exposed adhesive layer after Ar-GCIB etching is pressed onto the sample stage and fixed using a Mo plate. Then, ESCA analysis is performed using a scanning X-ray photoelectron spectrometer (ULVAC-PHI Quantum 2000) for wide-scan determination and qualitative analysis. Further narrow-scan determinations are performed on carbon, oxygen, and nitrogen elements, and the elemental ratios (atomic%) are calculated. Based on the obtained carbon (atomic%), oxygen (atomic%), and nitrogen (atomic%) ratios, the ratio of (number of carbon atoms) to (number of oxygen atoms + number of nitrogen atoms) is calculated.

[0148] <Panel Lighting Test>

[0149] The on-dash monitor (TKH703) manufactured by MAXWIN was disassembled, and the LCD panel was removed. The polarizing film attached to the visible side of the LCD panel was peeled off. Instead, the polarizing film of each embodiment and comparative example was cut to the same size as the polarizing film obtained from the LCD panel and bonded to it via an adhesive layer (20 μm thick) in the same manner as the peeled polarizing film along the transmission axis to obtain the LCD panel.

[0150] The LCD panel obtained above was placed in an environment of 65°C and 95% humidity for 1000 hours, and then placed in a normal temperature and humidity environment for 24 hours. It was then reinstalled in a monitor frame obtained by disassembling the LCD panel, and a black image was displayed and confirmed by visual observation. The results were categorized as follows: cases where only a black image was displayed were marked as ○, and cases where a part of the image showed a white, hazy display defect were marked as ×.

[0151] <Third Optical Film>

[0152] The third optical film used in the polarizing film configuration (1) described below is manufactured by the manufacturing method described below.

[0153] In a high-pressure reactor equipped with a stirrer, condenser, nitrogen inlet pipe, and thermometer, 48 parts by weight of hydroxypropyl methylcellulose (Shin-Etsu Chemical, trade name Metolose 60SH-50), 1560 parts by weight of distilled water, 8161 parts by weight of diisopropyl fumarate, 240 parts by weight of 3-ethyl-3-oxetanebutyl methyl acrylate, and 45 parts by weight of tert-butyl peroxypentanoate as a polymerization initiator were added. After nitrogen bubbling for 1 hour, the mixture was stirred and maintained at 49°C for 24 hours to carry out free radical suspension polymerization. The mixture was then cooled to room temperature, and the resulting suspension containing polymer particles was centrifuged. The obtained polymer was washed twice with distilled water and twice with methanol, and then dried under reduced pressure.

[0154] The obtained fumarate resin (a polymer with negative birefringence) was dissolved in a toluene / methyl ethyl ketone mixed solution (50 wt% / 50 wt% toluene / methyl ethyl ketone) to prepare a 20% solution. Then, 5 parts by weight of tributyl trimellitate as a plasticizer were added to 100 parts by weight of the fumarate resin to prepare a paste.

[0155] A biaxially oriented polyester (75 μm thick, 1350 mm wide) film was used as the support membrane. The tensile modulus (MD) of the support at 140 °C was 800 MPa.

[0156] The support film winding is placed in the feed section of the film-forming apparatus, and while the support film is fed out and transported downstream, it is heated in a heating furnace. The heating temperature is adjusted by changing the temperature of the atmosphere inside the heating furnace. The heating time is adjusted by changing the transport speed of the support. The adhesive prepared in Synthesis Example A is coated onto the heat-treated support to achieve a dried film thickness of 6.3 μm, and then dried at 140°C. The dried coating film and the support are wound together to form a laminate.

[0157] The aforementioned laminate was placed in the feed section of the stretching apparatus, and while being fed out and transported downstream, it underwent unidirectional stretching at its free end in a stretching furnace at a temperature of 140°C. The support was then peeled off from the stretched laminate to obtain a 6 μm thick retardation film. The stretching ratio was adjusted so that the in-plane retardation of the retardation film after peeling off the support was 35 nm.

[0158] Example 1

[0159] As an adhesive, an aqueous solution containing polyvinyl alcohol resin with acetylacetyl groups (average degree of polymerization 1200, degree of saponification 98.5 mol%, degree of acetylation 5 mol%) and hydroxymethyl melamine in a weight ratio of 3:1 was used. Using this adhesive, a second optical film (a cellulose triacetate film with a hard coating (manufactured by Fujifilm Co., Ltd., trade name "TG40UL", film thickness 40 μm)) was laminated on one side (the visible side) of the polarizer 1 at a temperature of 30°C using a roller laminator, and a first optical film (a cycloolefin film with phase difference (manufactured by Zeon Co., Ltd., trade name "ZT12", film thickness 17 μm)) was laminated on the other side (the image display unit side) of the polarizer 1. After drying in an oven, a laminated film with optical films stacked on both sides of the polarizer was manufactured.

[0160] Next, using an MCD coating machine (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, gravure roller line count: 1000 lines / inch, rotation speed 140% / pair line speed), an adhesive composition adjusted to the proportions described in Table 1 was applied to the cyclic olefin film side with phase difference of the above-obtained laminated film, and its thickness was increased to 1 μm. It was then bonded to the above-mentioned third optical film (film thickness 6 μm) using a roller press. Then, the adhesive composition was cured by irradiating the third optical film side with visible light through an active energy irradiation device. After curing, it was dried with hot air at 70°C for 3 minutes to obtain a polarizing film (the polarizing film constructed here is designated as "polarizing film construction (1)"). The thickness of the dried adhesive layer was 1 μm, and the bonding was carried out at a bonding line speed of 25 m / min.

[0161] The polarizing film of Example 1 was bonded to one side of 0.7 mm thick alkali-free glass via an adhesive layer (20 μm thick), thus preparing a sample for humidification durability testing. This sample was placed in an environment of 65°C-95% humidity and subjected to a humidification durability test for 1000 hours. For the humidification durability test evaluation sample after the durability test, on the other side of the alkali-free glass where the polarizing film of Example 1 was bonded but not to the polarizing film, an orthogonal Nicol polarizing film was bonded via an adhesive layer (20 μm thick) with the transmission axes of each polarizing film perpendicular to each other. The sample was then placed under a backlight (with the polarizing film of Example 1 on the upper surface), and the presence of any bright spots from foreign matter was investigated by visually observing the polarizing film of Example 1.

[0162] It can be seen that after 1000 hours of humidification durability test in an environment of 65℃-95% humidity, the polarizing film of Example 1 does not have bright spots from foreign objects more than 3mm from the end face.

[0163] Example 2

[0164] As an adhesive, an aqueous solution of polyvinyl alcohol resin containing acetylacetyl groups (average degree of polymerization 1200, degree of saponification 98.5 mol%, degree of acetylation 5 mol%) and hydroxymethyl melamine in a weight ratio of 3:1 was used. Using this adhesive, a second optical film (a cellulose triacetate film with a hard coating (manufactured by Fuji Film Co., Ltd., trade name "TG40UL", film thickness 40 μm)) was laminated onto one side (the visible side) of the polarizer 1 using a roller laminator at a temperature of 30°C. The film was then dried in an oven to produce a laminated film with an optical film stacked on one side of the polarizer.

[0165] Next, using an MCD coating machine (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb, gravure roller line count: 1000 lines / inch, rotation speed 140% / pair line speed), an adhesive composition adjusted to the amount described in Table 1 was applied to the polarizer 1 side of the above-mentioned laminated film, and its thickness was made to 1 μm. It was then bonded to the first optical film (cyclic olefin film (manufactured by ZEON Corporation, Japan, trade name "ZF14", film thickness 13 μm)) using a roller press. Then, the adhesive composition was cured by irradiating the cyclic olefin film side with visible light through an active energy irradiation device. After curing, it was dried with hot air at 70°C for 3 minutes to obtain a polarizing film (this polarizing film is designated as "polarizing film composition (2)"). The thickness of the dried adhesive layer was 1 μm. The bonding was carried out at a bonding line speed of 25 m / min.

[0166] For the polarizing film of Example 4, the same humidification durability test was performed as in Example 1, exposing it to an environment of 65°C-95% humidity for 1000 hours, and the presence of any bright spots from foreign matter was observed by the naked eye.

[0167] It can be seen that after 1000 hours of humidification durability test in an environment of 65℃-95% humidity, the polarizing film of Example 2 does not have bright spots from foreign objects more than 3mm from the end face.

[0168] Examples 3-6, Comparative Examples 1-6

[0169] The composition of the polarizing film, the formulation of the adhesive composition, and the type of polarizing lens were changed to the conditions described in Table 1. Otherwise, the presence or absence of bright spots from foreign objects was observed using the same method as in Examples 1-2.

[0170]

[0171] The details of each component listed in Table 1 are as follows.

[0172] (Monofunctional free radical polymeric compounds)

[0173] • Unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone (monomer component with hydroxyl group) (trade name "PLACCEL FA1DDM", manufactured by Daicel Co., Ltd., molecular weight 230.26, LogPow: 1.06)

[0174] Acryloylmorpholine (trade name "ACMO", manufactured by Kojin Co., Ltd., molecular weight 141.17, LogPow: -0.20)

[0175] ·Diethylacrylamide (trade name "DEAA", manufactured by KJ Chemical Co., Ltd., molecular weight 127.18, LogPow: 1.69)

[0176] • Lauryl acrylate (trade name "LIGHT ACRYLATE LA", manufactured by Kyoei Chemical Co., Ltd., molecular weight 240.39, LogPow: 6)

[0177] • Isostearyl acrylate (trade name "ISTA"), manufactured by Osaka Organic Chemicals Co., Ltd., molecular weight 324.5, LogPow: 7.46

[0178] • Dicyclopentyl acrylate (trade name "FANCRYL FA-513AS", manufactured by Hitachi Chemical Co., Ltd., molecular weight 206.28, LogPow: 2.58)

[0179] (Multifunctional free radical polymeric compounds)

[0180] • PEG400# diacrylate (trade name "LIGHT ACRYLATE 9EG-A", manufactured by Kyoei Chemical Co., Ltd., molecular weight 536.61, LogPow: -0.1)

[0181] ·Polypropylene glycol diacrylate (trade name "ARONIX M-220", manufactured by Toagosei Co., Ltd., molecular weight 300.35, LogPow: 1.68)

[0182] • 1,9-Nonadiol diacrylate (trade name "LIGHT ACRYLATE 1,9ND-A", manufactured by Kyoei Chemical Co., Ltd., molecular weight 268.35, LogPow: 3.68)

[0183] • Dimethyloltricyclodecane diacrylate (trade name "LIGHT ACRYLATE DCP-A", manufactured by Kyoei Chemical Co., Ltd., molecular weight 304.38, LogPow: 3.05)

[0184] (Acrylic oligomers)

[0185] • A 34 / 66 molar ratio copolymer oligomer of butyl acrylate and butyl methacrylate (trade name "ARUFON UP-1190", manufactured by Toa Synthetic Co., Ltd., molecular weight 1700, LogPow: 1.95)

[0186] (Initiator)

[0187] ·2-Methyl-1-[4-(methylthio)phenyl]-2-morpholinoprop-1-one (trade name "Omnirad 907", manufactured by IGMresins BV, molecular weight 279.13, LogPow: 2.09)

[0188] • Diethylthioxanone (trade name "KAYACURE DETX-S", manufactured by Nippon Kayaku Co., Ltd., molecular weight 268.37, LogPow: 5.12)

[0189] In Table 1, "(number of carbon atoms) / (number of oxygen atoms + number of nitrogen atoms)" refers to the value calculated based on the above-mentioned "method for determining the elemental ratio of the adhesive layer", "average logPow" refers to 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, and "distance from the end face to the foreign object (μm)" refers to the distance from the end face of the polarizing film to the bright spot from the foreign object that has been identified.

Claims

1. A polarizing film comprising: polarizer, and An adhesive layer adjacent to the polarizer or an optical film other than the polarizer. The polarizer contains zinc. Based on the elemental ratio determination of the adhesive layer, the ratio of (carbon atoms) / (oxygen atoms + nitrogen atoms) is 2.5 or higher, and the adhesive layer contains oxalic acid. After a humidification durability test in an environment of 65℃-95% humidity for 1000 hours, the polarizing film did not have any bright spots from foreign objects more than 3mm away from the end face.

2. The polarizing film according to claim 1, wherein, The polarizing film comprises: polarizer, An optical film laminated to at least one side of the polarizer via an aqueous adhesive layer, and An adhesive layer is disposed on the side of the optical film opposite to the aqueous adhesive layer.

3. The polarizing film according to claim 1 or 2, wherein, The adhesive layer is formed from the cured layer of an active energy radiation-curable adhesive composition.

4. The polarizing film according to claim 1 or 2, wherein, The adhesive layer is formed from 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 volume water absorption rate, expressed by the following formula, is less than 10% by weight. Formula: {(M2-M1) / M1}×100(%) Where M1: weight of the cured material before impregnation, and M2: weight of the cured material after impregnation.

5. The polarizing film according to claim 1 or 2, wherein, The adhesive layer is formed from a cured layer of the adhesive composition, and the logPow, representing the octanol / water partition coefficient, is greater than or equal to 1.6 based on the weighted average of the mole fractions of the monomer components contained in the adhesive composition.

6. The polarizing film according to claim 5, wherein, When the total amount of monomer components is set to 100 parts by weight, the adhesive composition contains 25 parts by weight or more of monomer components having an alkyl group having 8 or more carbon atoms.

7. The polarizing film according to claim 5, wherein, When the total amount of monomer components is set to 100 parts by weight, the adhesive composition contains 40 parts by weight or less of monomer components having hydroxyl groups.

8. An optical film having at least one polarizing film as described in any one of claims 1 to 7 stacked thereon.

9. An image display device that uses the polarizing film of any one of claims 1 to 7, and / or the optical film of claim 8.

Images