Image display panel and image display device

Abstract

To provide an image display panel having a polarizing film excellent in high-temperature durability.SOLUTION: The image display panel is obtained by laminating an image display cell 90, a first transparent protective film 12, an iodine polarizing film 11, and a second transparent protective film 13 in this order. The image display panel is such that: a moisture vapor transmission rate of the first transparent protective film is smaller than a moisture vapor transmission rate of the second transparent protective film, and is 200 g / (m2 24h) or less; and the iodine polarizing film satisfies a spectra area ratio represented by a general formula (1):b / a>1. (a represents a spectra area from 80 cm-1 to 130 cm-1 by Raman spectroscopic analysis in an area of 1 μm or more and 1.5 μm or less from the surface of the polarizing film at a first transparent protective film side; and b represents a spectra area from 80 cm-1 to 130 cm-1 by Raman spectroscopic analysis in an area of 1 μm or more and 1.5 μm or less from the surface of the polarizing film at a second transparent protective film side.)SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an image display panel and an image display device. [Background technology]

[0002] Conventionally, a dyed polyvinyl alcohol film (containing a dichroic substance such as iodine or a dichroic dye) has been used as a polarizing film for use in various image display devices such as liquid crystal display devices and organic EL display devices, because it has both high transmittance and high polarization degree. The polarizing film is produced by subjecting a polyvinyl alcohol film to various treatments such as swelling, dyeing, crosslinking, and stretching in a bath, followed by washing and drying. The polarizing film is usually used as a polarizing film (polarizing plate) with a protective film such as triacetyl cellulose attached to one or both sides of the polarizing film using an adhesive.

[0003] The polarizing film is used as a laminated polarizing film (optical laminate) by laminating other optical layers as necessary, and the polarizing film or the laminated polarizing film (optical laminate) is used as an image display panel bonded to an image display cell such as a liquid crystal cell or an organic EL element, and the image display panel is bonded to a front transparent plate (window layer) on the viewing side or a front transparent member such as a touch panel via a pressure-sensitive adhesive layer or an adhesive layer, and used as the various image display devices mentioned above (Patent Document 1).

[0004] In recent years, the applications of such various image display devices have expanded, for example, to be used as in-vehicle image display devices such as car navigation devices and rear monitors, in addition to mobile devices such as mobile phones and tablet terminals. Accordingly, the polarizing film and the laminated polarizing film are required to have higher durability in harsher environments (for example, high-temperature environments) than has been conventionally required, and polarizing films and image display devices intended to ensure such durability have been proposed (Patent Documents 2-3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-102353 A [Patent Document 2] Special Publication No. 2012-516468 [Patent Document 3] JP 2018-101117 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned in-vehicle image display devices, display designs are becoming increasingly irregular and larger due to the recent development of autonomous driving technology. Along with such changes in display design, there is a demand for a means to further improve the durability of polarizing films under high temperature environments.

[0007] In view of the above circumstances, an object of the present invention is to provide an image display panel having a polarizing film that is excellent in durability at high temperatures. [Means for solving the problem]

[0008] That is, the present invention provides an image display panel in which an image display cell, a first transparent protective film, an iodine-based polarizing film, and a second transparent protective film are laminated in this order, and the moisture permeability of the first transparent protective film is smaller than that of the second transparent protective film and is 200 g / (m 2 24h) or less, and the iodine-based polarizing film is such that b / a>1 (in the general formula (1), the first transparent protective film is bonded to one side of the iodine-based polarizing film, and the second transparent protective film is bonded to the other side of the iodine-based polarizing film, a is a value obtained by Raman spectroscopy analysis of a 80 cm -1 From 130cm -1b is the spectral area up to 80 cm in the region of 1 μm to 1.5 μm from the surface of the polarizing film on the second transparent protective film side, measured by Raman spectroscopy -1 From 130cm -1 The present invention relates to an image display panel that satisfies the spectral area ratio expressed by

[0009] The present invention also relates to an image display device comprising a front transparent member on the second transparent protective film side of the image display panel. Effect of the Invention

[0010] Although the details of the mechanism of action of the effect of the image display panel of the present invention are unclear, it is presumed as follows: However, the present invention is not interpreted as being limited to this mechanism of action.

[0011] The image display panel of the present invention comprises an image display cell, a first transparent protective film, an iodine-based polarizing film, and a second transparent protective film laminated in this order, and the moisture permeability of the first transparent protective film is smaller than that of the second transparent protective film and is 200 g / (m 2 24h) or less, and the iodine-based polarizing film is such that b / a>1 (in the general formula (1), the first transparent protective film is bonded to one side of the iodine-based polarizing film, and the second transparent protective film is bonded to the other side of the iodine-based polarizing film, a is a value obtained by Raman spectroscopy analysis of a 80 cm -1 From 130cm -1 b is the spectral area up to 80 cm in the region of 1 μm to 1.5 μm from the surface of the polarizing film on the second transparent protective film side, measured by Raman spectroscopy -1 From 130cm -1 The spectral area ratio shown above is 80 cm. -1 From 130cm -1As described in JP 2015-52676 A, the Raman shift is due to iodine (more specifically, an iodine complex (I 3 - )) peak (108cm -1 ) in the region from the surface of the polarizing film on the first transparent protective film side to a depth of 1 μm or more and 1.5 μm or less. 3 - The above b represents the concentration of iodine (iodine complex (I )) in the region of 1 μm to 1.5 μm from the surface of the polarizing film on the second transparent protective film side. 3 - Therefore, since the iodine-based polarizing film of the present invention satisfies the condition of general formula (1): b / a>1, the iodine (iodine complex (I 3 - The iodine concentration in a certain region from the first transparent protective film side (image display cell side) is lower than the iodine concentration in a certain region from the second transparent protective film side (viewing side of the image display panel).

[0012] On the other hand, it is presumed that iodine contained in the polarizing film promotes polyenation due to a dehydration reaction of polyvinyl alcohol in a high-temperature environment, thereby reducing the single transmittance of the polarizing film. Furthermore, when the above-mentioned image display panel is exposed to a high-temperature environment, the moisture in the polarizing film is difficult to be released outside the system on the image display cell side of the polarizing film, and the remaining moisture promotes deterioration of the polarizing film. Therefore, in the iodine-based polarizing film, the surface on the first transparent protective film side (image display cell side) is more severely deteriorated by polyenation than the surface on the second transparent protective film side (viewing side of the image display panel). As described above, the image display panel of the present invention is characterized in that the iodine (iodine complex (I 3 - The iodine concentration in a certain region from the first transparent protective film side (the image display cell side) is lower than the iodine concentration in a certain region on the second transparent protective film side (the viewing side of the image display panel), and therefore the film has excellent high-temperature durability.

[0013] The moisture permeability of the first transparent protective film is smaller than that of the second transparent protective film and is 200 g / (m 2 Since the retention time is 24 h or less, the polarizing film is less susceptible to the effect of moisture contained in the adhesive layer or the like provided on the image display cell side of the first transparent protective film, and moisture in the polarizing film can be effectively released toward the second transparent protective film side, so that the polarizing film has excellent high-temperature durability. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic cross-sectional view showing one embodiment of an image display panel and an image display device. [Diagram 2] 1 is a chart showing a Raman spectrum by Raman spectroscopic analysis of the polarizing film of the ultrathin section sample of Example 1. [Diagram 3] 1 is a graph showing the spectral area distribution (integral intensity distribution) from 80 cm −1 to 130 cm −1 by Raman spectroscopic analysis in the thickness direction of the polarizing film of Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Fig. 1 is a schematic cross-sectional view showing one embodiment of the image display panel of the present invention. Fig. 1 shows one embodiment of an image display panel 100 in which an image display cell 90, an adhesive layer or pressure-sensitive adhesive layer 20, a first transparent protective film 12, an iodine-based polarizing film 11, and a second transparent protective film 13 are laminated in this order. Fig. 1 also shows one embodiment of a polarizing film 10 including the first transparent protective film 12, the iodine-based polarizing film 11, and the second transparent protective film 13. Fig. 1 also shows one embodiment of an image display device 200 including a front transparent member 80 on the second transparent protective film side of the image display panel 100.

[0016] The image display panel of the present invention includes an image display cell, a first transparent protective film, an iodine-based polarizing film, and a second transparent protective film laminated in this order. The laminate including the first transparent protective film, the iodine-based polarizing film, and the second transparent protective film is called a polarizing film.

[0017] <Polarizing film> <Iodine-based polarizing film> The iodine-based polarizing film is formed by adsorbing and aligning iodine in a polyvinyl alcohol-based film. The polyvinyl alcohol (PVA)-based film can be used without any particular limitation as long as it has transparency in the visible light region and disperses and adsorbs iodine. In addition, the PVA-based film used as the raw material generally has a thickness of preferably about 1 to 100 μm, more preferably about 1 to 50 μm, and a width of preferably about 100 to 5000 mm.

[0018] The material of the polyvinyl alcohol-based film includes polyvinyl alcohol or its derivatives. Examples of the derivatives of polyvinyl alcohol include polyvinyl formal, polyvinyl acetal, olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, and those modified with alkyl esters and acrylamides. The polyvinyl alcohol preferably has an average degree of polymerization of about 100 to 10,000, more preferably about 1,000 to 10,000, and even more preferably about 1,500 to 4,500. The polyvinyl alcohol preferably has a saponification degree of about 80 to 100 mol%, and more preferably about 95 mol% to 99.95 mol. The average degree of polymerization and the saponification degree can be determined in accordance with JIS K 6726.

[0019] The polyvinyl alcohol-based film may contain additives such as plasticizers and surfactants. Examples of the plasticizers include polyols such as glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol, and condensates thereof. The amount of the additives used is not particularly limited, but is preferably about 20% by weight or less in the polyvinyl alcohol-based film.

[0020] The iodine-based polarizing film is an embodiment of a polarizing film in which the first transparent protective film is bonded to one side of the iodine-based polarizing film and the second transparent protective film is bonded to the other side of the iodine-based polarizing film, and a is a value obtained by Raman spectroscopy analysis of a region of 1 μm or more and 1.5 μm or less from the surface of the polarizing film on the first transparent protective film side. -1 From 130cm -1 b is the spectral area up to 80 cm in the region of 1 μm to 1.5 μm from the surface of the polarizing film on the second transparent protective film side, measured by Raman spectroscopy -1 From 130cm -1 The spectral area ratio expressed as

[0021] From the viewpoint of improving the high-temperature durability of the polarizing film, the above b / a is preferably 1.2 or more, and more preferably 1.5 or more.

[0022] In the iodine-based polarizing film, in the thickness direction from 1.5 μm or less from the surface of the polarizing film on the first transparent protective film side to 1.5 μm or less from the surface of the polarizing film on the second transparent protective film side, it is preferable that the iodine concentration increases, and more preferably the iodine concentration increases substantially monotonically, from the viewpoint of improving high-temperature durability while maintaining a certain initial optical performance. "Substantially increases monotonically" means that the distribution curve of the average iodine concentration in the thickness direction does not have a maximum value or a minimum value. Here, the average iodine concentration refers to the median value of the intensity measured by Raman analysis for each divided region by dividing the PVA-based resin film into 1 μm in the thickness direction. Therefore, even if the iodine concentration increases substantially monotonically, there may be a maximum and / or minimum region of the iodine concentration locally (i.e., within each divided region).

[0023] The iodine content of the iodine-based polarizing film is preferably 1% by weight or more and 15% by weight or less. From the viewpoint of suppressing color loss during a durability test, the iodine content of the iodine-based polarizing film is preferably 1.5% by weight or more, more preferably 2% by weight or more, and from the viewpoint of preventing polyenization, the iodine content is preferably 12% by weight or less, more preferably 10% by weight or less.

[0024] The iodine-based polarizing film has a single transmittance of preferably 40.0% or more, more preferably 41% or more, even more preferably 42% or more, and even more preferably 43% or more, and from the viewpoint of initial polarization performance, preferably 45% or less, and more preferably 44% or less. The single transmittance is a Y value measured using a UV-Vis spectrophotometer (Otsuka Electronics' "LPF-200") with a 2-degree visual field (C light source) according to JIS Z8701 and corrected for visibility. The measurement wavelength is 380 to 780 nm (5 nm intervals).

[0025] The iodine-based polarizing film preferably has a polarization degree of 99.8% or more, more preferably 99.9% or more, and even more preferably 99.95% or more.

[0026] The iodine-based polarizing film can be prepared, for example, by dyeing the polyvinyl alcohol-based film by immersing it in an aqueous solution of iodine, and stretching it to 3 to 7 times its original length. If necessary, it can also be immersed in an aqueous solution of boric acid, potassium iodide, or the like. Furthermore, if necessary, the polyvinyl alcohol-based film can be immersed in water and washed before dyeing. Washing the polyvinyl alcohol-based film with water can wash off dirt and antiblocking agents on the surface of the polyvinyl alcohol-based film, and also has the effect of preventing unevenness such as uneven dyeing by swelling the polyvinyl alcohol-based film. Stretching may be performed after dyeing with iodine, or may be performed while dyeing, or may be performed after stretching and dyeing with iodine. Stretching can be performed in an aqueous solution of boric acid, potassium iodide, or the like, or in a water bath.

[0027] The iodine-based polarizing film has a thickness of preferably 1 μm or more, more preferably 2 μm or more, from the viewpoint of improving the initial polarization degree of the polarizing film, and preferably 20 μm or less, more preferably 15 μm or less, even more preferably 10 μm or less, and even more preferably 8 μm or less, from the viewpoint of preventing warping of the panel. In particular, in order to obtain a polarizing film having a thickness of about 8 μm or less, the following method for producing a thin polarizing film can be applied, in which a laminate including a polyvinyl alcohol-based resin layer formed on a thermoplastic resin substrate is used as the polyvinyl alcohol-based film.

[0028] <Manufacturing method for thin iodine-based polarizing film> The method for producing a thin iodine-based polarizing film includes forming a polyvinyl alcohol-based resin layer (PVA-based resin layer) containing a polyvinyl alcohol-based resin (PVA-based resin) on one side of a long thermoplastic resin substrate to form a laminate, and subjecting the laminate to an air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment in this order. In particular, to obtain a polarizing film that satisfies the above condition of b / a>1 and has high optical properties, a two-stage stretching method is selected that combines an air-assisted stretching treatment (dry stretching) with an underwater stretching treatment in a boric acid aqueous solution.

[0029] The laminate may be prepared by any suitable method, for example, by applying a coating liquid containing the PVA resin to the surface of the thermoplastic resin substrate and drying the coating liquid. The thickness of the thermoplastic resin substrate is preferably about 20 to 300 μm, more preferably about 50 to 200 μm. The thickness of the PVA resin layer is preferably about 3 to 40 μm, more preferably about 3 to 20 μm.

[0030] The thermoplastic resin substrate preferably has a water absorption rate of about 0.2% or more, more preferably about 0.3% or more, from the viewpoint of absorbing water to greatly reduce the stretching stress and being able to be stretched at a high ratio. On the other hand, the thermoplastic resin substrate preferably has a water absorption rate of about 3% or less, more preferably about 1% or less, from the viewpoint of preventing defects such as a significant decrease in the dimensional stability of the thermoplastic resin substrate and a deterioration in the appearance of the resulting polarizing film. The water absorption rate can be adjusted, for example, by introducing a modifying group into the constituent material of the thermoplastic resin substrate. The water absorption rate is a value determined in accordance with JIS K 7209.

[0031] From the perspective of sufficiently ensuring the stretchability of the laminate while suppressing the crystallization of the PVA-based resin layer, the glass transition temperature (Tg) of the thermoplastic resin substrate is preferably about 120°C or lower. Further, considering the plasticization of the thermoplastic resin substrate by water and the good performance of stretching in water, the glass transition temperature (Tg) is more preferably about 100°C or lower, and even more preferably about 90°C or lower. On the other hand, from the perspective of preventing problems such as deformation of the thermoplastic resin substrate during coating and drying of the coating solution and being able to produce a good laminate, the glass transition temperature of the thermoplastic resin substrate is preferably about 60°C or higher. The glass transition temperature can be adjusted, for example, by introducing a modifying group into the constituent material of the thermoplastic resin substrate or heating using a crystallization material. The glass transition temperature (Tg) is a value determined in accordance with JIS K 7121.

[0032] As the constituent material of the thermoplastic resin substrate, any suitable thermoplastic resin can be adopted. Examples of the thermoplastic resin include ester-based resins such as polyethylene terephthalate-based resins, cycloolefin-based resins such as norbornene-based resins, olefin-based resins such as polypropylene, polyamide-based resins, polycarbonate-based resins, and copolymer resins thereof. Among these, norbornene-based resins and amorphous (non-crystalline) polyethylene terephthalate-based resins are preferred. Further, from the perspective that the thermoplastic resin substrate is extremely excellent in stretchability and the crystallization during stretching can be suppressed, amorphous (non-crystalline) polyethylene terephthalate-based resins are preferably used. Examples of the amorphous (non-crystalline) polyethylene terephthalate-based resins include copolymers containing isophthalic acid and / or cyclohexanedicarboxylic acid as dicarboxylic acids, and copolymers containing cyclohexanedimethanol or diethylene glycol as glycols.

[0033] The thermoplastic resin substrate may be subjected to a surface treatment (e.g., corona treatment, etc.) before forming the PVA-based resin layer, or an easy-adhesion layer may be formed on the thermoplastic resin substrate. By carrying out such treatment, the adhesion between the thermoplastic resin substrate and the PVA-based resin layer can be improved. In addition, the thermoplastic resin substrate may be stretched before forming the PVA-based resin layer.

[0034] The coating liquid is a solution in which a PVA-based resin is dissolved in a solvent. Examples of the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine, with water being preferred. These can be used alone or in combination of two or more. The concentration of the PVA-based resin in the coating liquid is preferably about 3 to 20 parts by weight relative to 100 parts by weight of the solvent, from the viewpoint of forming a uniform coating film that is in close contact with the thermoplastic resin substrate.

[0035] The coating liquid preferably contains a halide from the viewpoint of improving the orientation of polyvinyl alcohol molecules by stretching. Any appropriate halide can be used as the halide, and examples thereof include iodide and sodium chloride. Examples of the iodide include potassium iodide, sodium iodide, and lithium iodide, and potassium iodide is preferred. The concentration of the halide in the coating liquid is preferably about 5 to 20 parts by weight, and more preferably about 10 to 15 parts by weight, based on 100 parts by weight of the PVA resin.

[0036] The coating liquid may contain additives, such as plasticizers, such as ethylene glycol and glycerin, and surfactants, such as nonionic surfactants.

[0037] The coating method of the coating liquid may be any appropriate method, such as roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, knife coating (comma coating, etc.), etc. The drying temperature of the coating liquid is preferably about 50° C. or higher.

[0038] The in-air auxiliary stretching process can stretch the laminate at a high stretch ratio while suppressing crystallization of the thermoplastic resin substrate. The stretching method of the in-air auxiliary stretching process may be fixed-end stretching (e.g., a method of stretching using a tenter stretching machine) or free-end stretching (e.g., a method of uniaxially stretching the laminate by passing it between rolls having different peripheral speeds), but free-end stretching is preferred from the viewpoint of obtaining high optical properties.

[0039] The stretching ratio in the auxiliary in-air stretching is preferably about 2 to 3.5 times, and more preferably about 2.2 to 2.6 times, from the viewpoint of satisfying the above condition of b / a>1. The auxiliary in-air stretching may be performed in one stage or in multiple stages. When performed in multiple stages, the stretching ratio is the product of the stretching ratios in each stage.

[0040] The stretching temperature in the auxiliary in-air stretching can be set to any appropriate value depending on the material forming the thermoplastic resin substrate, the stretching method, etc., and is, for example, preferably equal to or higher than the glass transition temperature (Tg) of the thermoplastic resin substrate, more preferably equal to or higher than the glass transition temperature (Tg) + 10° C., and even more preferably equal to or higher than the glass transition temperature (Tg) + 15° C. On the other hand, the upper limit of the stretching temperature is preferably about 170° C., from the viewpoint of suppressing rapid crystallization of the PVA-based resin and suppressing defects due to crystallization (for example, preventing the orientation of the PVA-based resin layer due to stretching).

[0041] If necessary, an insolubilization treatment may be performed after the auxiliary air stretching treatment and before the dyeing treatment or the underwater stretching treatment. The insolubilization treatment is typically performed by immersing the PVA-based resin layer in an aqueous solution of boric acid. By performing the insolubilization treatment, water resistance is imparted to the PVA-based resin layer, and it is possible to prevent a decrease in the orientation of PVA when immersed in water. The concentration of the aqueous solution of boric acid is preferably about 1 to 5 parts by weight relative to 100 parts by weight of water. The liquid temperature of the insolubilization bath is preferably about 20 to 50°C.

[0042] The dyeing treatment is performed by dyeing the PVA-based resin layer with iodine. Examples of the adsorption method include a method of immersing the PVA-based resin layer (laminate) in a dyeing solution containing iodine, a method of applying the dyeing solution to the PVA-based resin layer, and a method of spraying the dyeing solution onto the PVA-based resin layer, and the like. The method of immersing the PVA-based resin layer (laminate) in a dyeing solution containing iodine is preferred.

[0043] The amount of iodine in the dye bath is preferably about 0.05 to 0.5 parts by weight relative to 100 parts by weight of water. In order to increase the solubility of iodine in water, it is preferable to mix the iodide in the iodine aqueous solution. The amount of iodide is preferably about 0.1 to 10 parts by weight, more preferably about 0.3 to 5 parts by weight, relative to 100 parts by weight of water. The liquid temperature of the dye bath is preferably about 20 to 50°C in order to suppress dissolution of the PVA-based resin. In addition, the immersion time is preferably about 5 seconds to 5 minutes, more preferably about 20 to 90 seconds, and even more preferably about 30 to 50 seconds, from the viewpoint of satisfying the above condition of b / a>1 and ensuring the transmittance of the PVA-based resin layer. In order to obtain a polarizing film having good optical properties, the ratio of the contents of iodine and iodide in the iodine aqueous solution is preferably about 1:5 to 1:20, more preferably about 1:5 to 1:10.

[0044] If necessary, a crosslinking treatment may be performed after the dyeing treatment and before the underwater stretching treatment. The crosslinking treatment is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. The crosslinking treatment imparts water resistance to the PVA-based resin layer, and prevents the orientation of the PVA from decreasing when the layer is immersed in high-temperature water in the subsequent underwater stretching. The boric acid concentration of the aqueous boric acid solution is preferably about 1 to 5 parts by weight relative to 100 parts by weight of water. In addition, when the crosslinking treatment is performed, it is preferable to further add the iodide to the crosslinking bath in the crosslinking treatment. By adding the iodide, it is possible to suppress the elution of iodine adsorbed to the PVA-based resin layer. The amount of the iodide added is preferably about 1 to 5 parts by weight relative to 100 parts by weight of water. The liquid temperature of the crosslinking bath (aqueous boric acid solution) is preferably about 20 to 50°C.

[0045] The underwater stretching treatment is performed by immersing the laminate in a stretching bath. According to the underwater stretching treatment, stretching can be performed at a temperature lower than the glass transition temperature (typically about 80° C.) of the thermoplastic resin substrate or the PVA-based resin layer, and the PVA-based resin layer can be stretched at a high magnification while suppressing crystallization. The stretching method of the underwater stretching treatment may be fixed-end stretching (for example, a method of stretching using a tenter stretching machine) or free-end stretching (for example, a method of uniaxially stretching the laminate by passing it between rolls with different peripheral speeds), but free-end stretching is preferred from the viewpoint of obtaining high optical properties.

[0046] The underwater stretching treatment is preferably performed by immersing the laminate in an aqueous boric acid solution (stretching in an aqueous boric acid solution). By using an aqueous boric acid solution as the stretching bath, it is possible to impart to the PVA-based resin layer rigidity that can withstand the tension applied during stretching and water resistance that does not dissolve in water. The boric acid concentration of the aqueous boric acid solution is preferably 1 to 10 parts by weight, more preferably 2.5 to 6 parts by weight, per 100 parts by weight of water. In addition, an iodide may be blended into the stretching bath (aqueous boric acid solution). The liquid temperature of the stretching bath is preferably about 40 to 85°C, more preferably about 60 to 75°C. The immersion time of the laminate in the stretching bath is preferably about 15 seconds to 5 minutes.

[0047] The stretching ratio in the underwater stretching is preferably about 1.5 times or more, and more preferably about 3 times or more.

[0048] The total stretching ratio of the laminate is preferably about 5 times or more, and more preferably about 5.5 times or more, relative to the original length of the laminate.

[0049] The drying shrinkage treatment may be performed by zone heating in which the entire zone is heated, or by heating the transport roll (using a so-called heating roll), but preferably both are used. By drying using a heating roll, it is possible to efficiently suppress the heat curl of the laminate and produce a polarizing film with excellent appearance, and since the laminate can be dried while being kept flat, it is possible to suppress not only curling but also wrinkles. In addition, from the viewpoint of improving the optical properties of the obtained polarizing film by shrinking in the width direction during the drying shrinkage treatment, the shrinkage rate in the width direction of the laminate due to the drying shrinkage treatment is preferably about 1 to 10%, more preferably about 2 to 8%.

[0050] Drying conditions can be controlled by adjusting the heating temperature of the transport rolls (temperature of the heating rolls), the number of heating rolls, contact time with the heating rolls, etc. The temperature of the heating rolls is preferably about 60 to 120°C, more preferably about 65 to 100°C, and even more preferably 70 to 80°C. From the viewpoint of satisfactorily increasing the crystallinity of the thermoplastic resin and satisfactorily suppressing curling, the number of transport rolls is usually about 2 to 40, preferably about 4 to 30. The contact time (total contact time) between the laminate and the heating rolls is preferably about 1 to 300 seconds, more preferably 1 to 20 seconds, and even more preferably 1 to 10 seconds.

[0051] The heating roll may be installed in a heating furnace or in a normal production line (under room temperature environment). It is preferably installed in a heating furnace equipped with a blowing means. By using drying with the heating roll and hot air drying in combination, it is possible to suppress a steep temperature change between the heating rolls, and it is possible to easily control the shrinkage in the width direction. The hot air drying temperature is preferably about 30 to 100°C. In addition, the hot air drying time is preferably about 1 to 300 seconds.

[0052] After the underwater stretching treatment, and before the drying shrinkage treatment, it is preferable to carry out a washing treatment, typically by immersing the PVA-based resin layer in an aqueous potassium iodide solution.

[0053] In addition, each treatment bath in the dyeing process, the underwater stretching process, the insolubilization process, the crosslinking process, and the washing process may contain additives such as zinc salts, pH adjusters, pH buffers, and other salts. Examples of the zinc salts include zinc halides such as zinc chloride and zinc iodide; inorganic zinc salts such as zinc sulfate and zinc acetate. Examples of the pH adjusters include strong acids such as hydrochloric acid, sulfuric acid, and nitric acid, and strong bases such as sodium hydroxide and potassium hydroxide. Examples of the pH buffers include carboxylic acids such as acetic acid, oxalic acid, and citric acid, and salts thereof, and inorganic weak acids such as phosphoric acid and carbonic acid, and salts thereof. Examples of the other salts include chlorides such as sodium chloride, potassium chloride, and barium chloride, nitrates such as sodium nitrate and potassium nitrate, sulfates such as sodium sulfate and potassium sulfate, and salts of alkali metals and alkaline earth metals.

[0054] <First and second transparent protective films> The first and second transparent protective films have a moisture permeability of 200 g / (m 2·24h) or less, there is no particular limitation, and various transparent protective films used in polarizing films can be used. As a material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture blocking property, isotropy, etc. can be used. As the thermoplastic resin, for example, cellulose ester resin such as triacetyl cellulose, polyester resin such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone resin, polysulfone resin, polycarbonate resin, polyamide resin such as nylon and aromatic polyamide, polyimide resin, polyolefin resin such as polyethylene, polypropylene, and ethylene-propylene copolymer, (meth)acrylic resin, cyclic polyolefin resin (norbornene resin) having a cyclo- or norbornene structure, polyarylate resin, polystyrene resin, polyvinyl alcohol resin, and mixtures thereof can be used. In addition, the transparent protective film can be a cured layer formed from a thermosetting resin or an ultraviolet-curing resin such as a (meth)acrylic, urethane, acrylic urethane, epoxy, or silicone. Among these, cellulose ester resins, polycarbonate resins, (meth)acrylic resins, cyclic polyolefin resins, and polyester resins are preferred.

[0055] The thickness of the first and second transparent protective films can be determined as appropriate, but generally, from the standpoint of workability such as strength and handleability, thinness, etc., it is preferably about 1 to 500 μm, more preferably about 1 to 300 μm, and even more preferably about 5 to 100 μm.

[0056] The transparent protective film may be a retardation plate having a front retardation of 40 nm or more and / or a thickness retardation of 80 nm or more. The front retardation is usually controlled to be in the range of 40 to 200 nm, and the thickness retardation is usually controlled to be in the range of 80 to 300 nm. When a retardation plate is used as the transparent protective film, the retardation plate also functions as the transparent protective film, so that the film can be made thinner.

[0057] Examples of the retardation plate include a birefringent film obtained by uniaxial or biaxial stretching of a polymeric material, an oriented film of a liquid crystal polymer, and an oriented layer of a liquid crystal polymer supported by a film. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm. The retardation plate may be used by laminating it to a transparent protective film that does not have a retardation.

[0058] The first and second transparent protective films may contain any appropriate additives such as an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, an antistatic agent, a pigment, a colorant, etc. In particular, when the transparent protective film contains an ultraviolet absorber, the light resistance of the polarizing film can be improved.

[0059] The first transparent protective film has a moisture permeability of 200 g / (m 2 From the viewpoint of suppressing a decrease in the polarization degree of the polarizing film in a high-temperature and high-humidity environment, the first transparent protective film has a moisture permeability of 100 g / (m 2 ·24h) or less, and 50 / (m 2 From the viewpoint of production efficiency in the drying process after laminating the polarizing film and the transparent protective film, the second transparent protective film has a moisture permeability of 250 g / (m 2 24h) or more, and 300g / (m 2 From the viewpoint of preventing the deterioration of the polarization degree of the polarizing film in a high-temperature and high-humidity environment, the moisture permeability is preferably 1,000 g / (m 2 24h) or less, and 600g / (m 2 The moisture permeability can be calculated according to the moisture permeability test (cup method) of JIS Z0208 by cutting a sample to a diameter of 60 mm, placing it in a moisture permeability cup containing about 15 g of calcium chloride, placing it in an incubator at a temperature of 40°C and a humidity of 90% RH, and measuring the increase in weight of calcium chloride before and after leaving it for 24 hours.

[0060] The surfaces of the first and second transparent protective films on which the polarizing film is not attached may be provided with functional layers such as a hard coat layer, an anti-reflection layer, an anti-sticking layer, a diffusion layer, an anti-glare layer, etc. The above-mentioned functional layers such as the hard coat layer, the anti-reflection layer, the anti-sticking layer, the diffusion layer, the anti-glare layer, etc. may be provided on the protective film itself, or may be provided separately from the protective film.

[0061] The polarizing film and the first and second transparent protective films, and the first and second transparent protective films and the functional layer are usually bonded together via a pressure-sensitive adhesive layer or an adhesive layer.

[0062] As the adhesive forming the adhesive layer, various adhesives used in polarizing films can be used, and examples thereof include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinyl porolidone-based adhesives, polyacrylamide-based adhesives, cellulose-based adhesives, etc. Among these, acrylic-based adhesives are preferred.

[0063] Examples of the method for forming the adhesive layer include a method in which the adhesive is applied to a release-treated separator or the like, dried to form an adhesive layer, and then transferred to a polarizing film or the like, or a method in which the adhesive is applied to a polarizing film or the like, dried to form an adhesive layer, etc. The thickness of the adhesive layer is not particularly limited and is, for example, about 1 to 100 μm, and preferably about 2 to 50 μm.

[0064] The adhesive layer may be formed by any of various adhesives used in polarizing films, including, for example, isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl latex-based adhesives, and water-based polyesters. These adhesives are usually used as adhesives made of aqueous solutions (water-based adhesives), and contain 0.5 to 60% by weight of solids. Among these, polyvinyl alcohol-based adhesives are preferred, and acetoacetyl group-containing polyvinyl alcohol-based adhesives are more preferred.

[0065] The water-based adhesive may contain a crosslinking agent. As the crosslinking agent, a compound having at least two functional groups in one molecule that are reactive with the polymer or other components constituting the adhesive is usually used, and examples of the crosslinking agent include alkylenediamines, isocyanates, epoxies, aldehydes, and amino-formaldehydes such as methylol urea and methylol melamine. The amount of the crosslinking agent in the adhesive is usually about 10 to 60 parts by weight based on 100 parts by weight of the polymer or other components constituting the adhesive.

[0066] In addition to the above, examples of the adhesive include active energy ray curable adhesives such as ultraviolet ray curable adhesives and electron beam curable adhesives. Examples of the active energy ray curable adhesives include (meth)acrylate adhesives. Examples of the curable components in the (meth)acrylate adhesives include compounds having a (meth)acryloyl group and compounds having a vinyl group. Examples of the compounds having a (meth)acryloyl group include alkyl (meth)acrylates such as linear alkyl (meth)acrylates, alicyclic alkyl (meth)acrylates, and polycyclic alkyl (meth)acrylates having 1 to 20 carbon atoms; hydroxyl group-containing (meth)acrylates; and epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate. The (meth)acrylate adhesive may contain nitrogen-containing monomers such as hydroxyethyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, (meth)acrylamide, and (meth)acryloyl morpholine. The (meth)acrylate adhesive may contain polyfunctional monomers such as tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, cyclic trimethylolpropane formal acrylate, dioxane glycol diacrylate, and EO-modified diglycerin tetraacrylate as a crosslinking component. In addition, compounds having epoxy groups or oxetanyl groups can also be used as cationic polymerization curing adhesives. The compound having an epoxy group is not particularly limited as long as it has at least two epoxy groups in the molecule, and various commonly known curing epoxy compounds can be used.

[0067] The adhesive may contain appropriate additives as necessary, such as coupling agents, such as silane coupling agents and titanium coupling agents, adhesion promoters, such as ethylene oxide, ultraviolet absorbers, deterioration inhibitors, dyes, processing aids, ion trapping agents, antioxidants, tackifiers, fillers, plasticizers, leveling agents, foaming inhibitors, antistatic agents, heat stabilizers, and hydrolysis stabilizers.

[0068] The adhesive may be applied to either the first and second transparent protective film side (or the functional layer side) or the polarizing film side, or may be applied to both. After lamination, a drying step is performed to form an adhesive layer consisting of a coated and dried layer. After the drying step, ultraviolet rays or electron beams may be irradiated as necessary. The thickness of the adhesive layer is not particularly limited, and when a water-based adhesive or the like is used, it is preferably about 30 to 5000 nm, more preferably about 100 to 1000 nm, and when a UV-curable adhesive, an electron beam-curable adhesive, or the like is used, it is preferably about 0.1 to 100 μm, more preferably about 0.5 to 10 μm.

[0069] In particular, from the viewpoint of production efficiency, an active energy ray-curable adhesive is preferable as the adhesive for bonding the polarizing film and the first transparent protective film.

[0070] The polarizing film, the first and second transparent protective films, and the functional layer may be subjected to a surface modification treatment or an easy-adhesion treatment.

[0071] Examples of the surface modification treatment include corona treatment, plasma treatment, primer treatment, and saponification treatment.

[0072] Examples of the easy-adhesion treatment include treatment with a forming material containing various resins having a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone-based skeleton, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, or the like.

[0073] The first and second transparent protective films and the polarizing film, and the first and second transparent protective films and the functional layer may be laminated via an intervening layer such as a blocking layer or a refractive index adjusting layer.

[0074] The blocking layer is a layer having a function of preventing impurities such as oligomers and ions eluted from a transparent protective film, etc. from migrating (penetrating) into the polarizing film. The blocking layer may be any layer that is transparent and can prevent impurities from eluting from a transparent protective film, etc., and examples of materials for forming the blocking layer include urethane prepolymer-based forming materials, cyanoacrylate-based forming materials, and epoxy-based forming materials.

[0075] The refractive index adjusting layer is a layer provided to suppress a decrease in transmittance caused by reflection between layers having different refractive indices such as the transparent protective film and a polarizing film, etc. Examples of the refractive index adjusting material forming the refractive index adjusting layer include forming agents containing various resins and additives such as silica-based, acrylic-based, acrylic-styrene-based, and melamine-based resins.

[0076] The polarizing film may be a laminated polarizing film (optical laminate) in which the polarizing film is laminated to an optical layer. The optical layer is not particularly limited, and may be, for example, one or more optical layers that may be used in the formation of liquid crystal displays, such as a reflector, a semi-transmitting plate, a retardation plate (including a wavelength plate such as 1 / 2 or 1 / 4), or a viewing angle compensation film. Examples of the laminated polarizing film include a reflective polarizing film or a semi-transmitting polarizing film in which a reflector or a semi-transmitting reflector is further laminated on the polarizing film, an elliptical polarizing film or a circular polarizing film in which a retardation plate is further laminated on the polarizing film, a wide viewing angle polarizing film in which a viewing angle compensation film is further laminated on the polarizing film, and a polarizing film in which a brightness improvement film is further laminated on the polarizing film.

[0077] An adhesive layer for bonding an image display cell such as a liquid crystal cell or an organic EL element and other members such as a front transparent plate or a front transparent member such as a touch panel on the viewing side may be provided on one or both surfaces of the polarizing film or the laminated polarizing film. The adhesive layer is preferably a pressure-sensitive adhesive layer. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited, and may be appropriately selected and used from those having, as a base polymer, an acrylic polymer, a silicone polymer, polyester, polyurethane, polyamide, polyether, a fluorine-based polymer, a rubber-based polymer, or the like. In particular, a pressure-sensitive adhesive having excellent optical transparency, moderate wettability, cohesiveness, and adhesiveness, and excellent weather resistance, heat resistance, etc., such as a pressure-sensitive adhesive containing an acrylic polymer, is preferably used.

[0078] The adhesive layer can be applied to one or both sides of the polarizing film or the laminated polarizing film by an appropriate method. For example, the adhesive layer can be applied by preparing an adhesive solution and applying it directly to the polarizing film or the laminated polarizing film by an appropriate spreading method such as a casting method or a coating method, or by forming an adhesive layer on a separator and transferring it onto the polarizing film or the laminated polarizing film. The thickness of the adhesive layer can be appropriately determined depending on the purpose of use, adhesive strength, etc., and is generally 1 to 500 μm, preferably 5 to 200 μm, and more preferably 10 to 100 μm. In this way, the polarizing film or the laminated polarizing film having an adhesive layer on at least one side is called an adhesive layer-attached polarizing film or an adhesive layer-attached laminated polarizing film.

[0079] It is preferable that a separator is temporarily attached to cover the exposed surface of the pressure-sensitive adhesive layer for the purpose of preventing contamination, etc., until the pressure-sensitive adhesive layer is put into practical use. This prevents contamination, etc., of the pressure-sensitive adhesive layer under normal handling conditions. As the separator, for example, a suitable thin material such as a plastic film, a rubber sheet, paper, cloth, nonwoven fabric, net, foam sheet, metal foil, or a laminate thereof, which is coated with a suitable release agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide-based, as necessary, is used.

[0080] <Image display cell> Examples of the image display cell include liquid crystal cells and organic EL cells. The liquid crystal cell may be, for example, a reflective liquid crystal cell that uses external light, a transmissive liquid crystal cell that uses light from a light source such as a backlight, or a semi-transmissive semi-reflective liquid crystal cell that uses both external light and light from a light source. When the liquid crystal cell uses light from a light source, the image display device (liquid crystal display device) has a polarizing film disposed on the opposite side to the viewing side of the image display cell (liquid crystal cell), and further has a light source disposed thereon. The polarizing film on the light source side and the liquid crystal cell are preferably bonded together via an appropriate adhesive layer. The liquid crystal cell may be driven in any type, such as a VA mode, an IPS mode, a TN mode, an STN mode, or a bend orientation (π type).

[0081] As the organic EL cell, for example, a light-emitting body (organic electroluminescence light-emitting body) formed by sequentially laminating a transparent electrode, an organic light-emitting layer, and a metal electrode on a transparent substrate is preferably used. The organic light-emitting layer is a laminate of various organic thin films, and various layer configurations can be adopted, such as a laminate of a hole injection layer made of a triphenylamine derivative or the like and a light-emitting layer made of a fluorescent organic solid such as anthracene, a laminate of these light-emitting layers and an electron injection layer made of a perylene derivative or the like, or a laminate of a hole injection layer, a light-emitting layer, and an electron injection layer.

[0082] <Image display device> The image display device of the present invention further comprises a front transparent member on the second transparent protective film side of the image display panel.

[0083] Examples of the front transparent member disposed on the viewing side of the image display cell include a front transparent plate (window layer) and a touch panel. As the front transparent plate, a transparent plate having appropriate mechanical strength and thickness is used. As such a transparent plate, for example, a transparent resin plate such as an acrylic resin or a polycarbonate resin, or a glass plate is used. As the touch panel, for example, various touch panels such as a resistive film type, a capacitive type, an optical type, an ultrasonic type, etc., a glass plate or a transparent resin plate having a touch sensor function, etc. are used. When a capacitive type touch panel is used as the front transparent member, it is preferable that a front transparent plate made of glass or a transparent resin plate is provided on the viewing side further than the touch panel. EXAMPLES

[0084] The present invention will be described in more detail below by way of examples, but the present invention is not limited to these examples.

[0085] <Example 1> <Preparation of iodine-based polarizing film> One side of an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) substrate with a water absorption rate of 0.75% and a Tg of 75°C was subjected to a corona treatment, and an aqueous solution containing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (polymerization degree 1200, acetoacetyl-modification degree 4.6%, saponification degree 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product name "GOHSEFYMER Z410") in a ratio of 9:1 was applied to the corona-treated surface and dried at 25°C to form a PVA-based resin layer with a thickness of 13 μm, and a laminate was produced. The obtained laminate was uniaxially stretched at free ends to 2.4 times in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds in an oven at 130°C (air-assisted stretching treatment). Next, the laminate was immersed in an insolubilizing bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) with a liquid temperature of 40°C for 30 seconds (insolubilizing treatment). Next, the laminate was immersed in a dyeing bath (an iodine aqueous solution obtained by blending iodine and potassium iodide in a weight ratio of 1:7 with respect to 100 parts by weight of water) with a liquid temperature of 30°C for 40 seconds while adjusting the iodine concentration so that the polarizing film finally obtained had a predetermined single transmittance (dyeing treatment). Next, the laminate was immersed in a crosslinking bath (a boric acid aqueous solution obtained by blending 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) with a liquid temperature of 40°C for 30 seconds (crosslinking treatment). Thereafter, the laminate was immersed in a boric acid aqueous solution (aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) with a liquid temperature of 70°C. While stretching, the laminate was uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to a total stretch ratio of 5.5 times (underwater stretching treatment). Thereafter, the laminate was immersed in a cleaning bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) with a liquid temperature of 20°C (cleaning treatment). Thereafter, while drying in an oven maintained at 90°C, the laminate was brought into contact with a SUS heated roll with a surface temperature maintained at 75°C for about 2 seconds (drying shrinkage treatment). As a result, an optical film laminate including a polarizing film with a thickness of 5.4 μm was obtained. The iodine concentration in the polarizing film measured by the following method was 7.1% by weight, and the single transmittance was 43.5%.

[0086] <Method for measuring iodine concentration (wt%) in polarizing film> The iodine concentration (wt %) of the polarizing film was determined using an X-ray fluorescence analyzer (manufactured by Rigaku Corporation, product name "ZSX-PRIMUS IV", measurement diameter: ψ20 mm) according to the following formula. Iodine concentration (wt%) = 14.474 × (fluorescent X-ray intensity) / (film thickness) (kcps / μm) Note that the coefficient used to calculate the concentration differs depending on the measuring device, but the coefficient can be determined using an appropriate calibration curve.

[0087] <Preparation of polarizing film> As the second transparent protective film, a 48 μm-thick triacetyl cellulose (TAC) film with a hard coat layer (Fujifilm "TJ40UL", moisture permeability 300 g / (m 2 The triacetyl cellulose surface of the optical film laminate was bonded to the polarizing film surface of the optical film laminate by a roll laminator via a UV-curable adhesive, and then the adhesive was cured by irradiating the polarizing film with ultraviolet rays as active energy rays. Next, a corona treatment was performed on the polarizing film surface from which the polyethylene terephthalate film had been peeled off, and a cycloolefin (COP) film (Zeon Corporation "ZT12" with a moisture permeability of 20 g / (m2)) with a thickness of 18 μm was applied as a first transparent protective film. 2 The polarizing film was then prepared by bonding the polarizing film to the corona-treated surface of the polarizing film via the UV-curable adhesive, and then irradiating the polarizing film with UV rays as active energy rays to cure the adhesive. The UV irradiation was performed using a gallium-filled metal halide lamp, irradiation device: Light HAMMER10 manufactured by Fusion UV Systems, Inc., bulb: V bulb, peak irradiance: 1600 mW / cm. 2 , cumulative dose 1000 / mJ / cm 2 (wavelength 380-440 nm) was used, and the UV irradiance was measured using a Sola-Check system manufactured by Solatell.

[0088] <Measurement of Spectral Area Ratio by Raman Spectroscopic Analysis> A 100 nm thick cross-sectional slice (analysis sample) was prepared using a microtome in a direction parallel to the absorption axis of the polarizing film obtained above, and the Raman spectrum was then measured at measurement points spaced 0.1 μm apart along the thickness of the polarizing film. The polarization plane of the laser light was incident parallel to the absorption axis direction (stretching direction) of the polarizing film and perpendicular to the cross section of the polarizing film of the ultra-thin slice sample. Next, as shown in Figure 2, the Raman spectrum obtained at each measurement point was analyzed at a wavenumber of 80 cm. -1 ~130cm -1 The integral intensity in the range of 80 cm -1 Raman intensity at 130 cm -1 The straight line connecting each point of Raman intensity at each point was used as the baseline (shown by the dashed line). The integrated intensity distribution in the thickness direction of the polarizing film was calculated from the integrated intensities at each measurement point. The results are shown in Figure 3. Furthermore, -1 ~130cm -1 The spectral area (integral intensity) of the section is a, and the distance from the surface of the polarizing film on the protective film B side to the -1 ~130cm -1 The ratio (b / a) was calculated when the spectral area (integral intensity) of the interval was b. The results are shown in Table 1. The measurement conditions for Raman spectroscopy are as follows. [Raman spectroscopic analysis conditions] Measurement equipment: Jobin Yvon SAS Laser Raman microscope "LabRAM HR800" ·Measurement focus: outermost surface ·Measurement wavelength: approx. 30~600cm -1 Laser wavelength: 514nm Neutral density filter: D4 (incident laser power x 0.0001) Lens: x100 (NA 0.9) Laser power: 6mW

[0089] <Fabrication of pseudo image display panel> The cycloolefin film surface of the polarizing film obtained above was attached to a small piece of glass measuring 25×40 mm via an adhesive to prepare a pseudo image display panel.

[0090] <Evaluation of high temperature durability> The pseudo image display panel obtained above was placed in a hot air oven at a temperature of 110°C for 120 hours, and the single-piece transmittance (ΔTs) was measured before and after placement (heating). The single-piece transmittance was measured using a spectrophotometer (Otsuka Electronics Co., Ltd., LPF-200). The single-piece transmittance is a Y value corrected for visibility using a 2-degree visual field (C light source) according to JIS Z 8701-1982. The measurement wavelength was 380 to 780 nm (every 5 nm). ΔTs(%)=Ts 120 -Ts 0 Here, Ts 0 is the initial (before heating) single unit transmittance, and Ts 120 is the single piece transmittance after heating for 120 hours. ○: ΔTs(%) is 0% or more and less than 3% ×: ΔTs(%) is less than 0% or more than 3%

[0091] <Example 2> As the second transparent protective film, a 47 μm-thick triacetyl cellulose (TAC) film with a hard coat layer (Fujifilm "TJ40UL", moisture permeability 300 g / (m 2 A polarizing film and a pseudo image display panel were produced and evaluated in the same manner as in Example 1, except that the triacetyl cellulose surface of the optical film laminate (.24h)) was bonded to the polarizing film surface of the optical film laminate via a water-based adhesive using a roll laminator, and then the adhesive was cured by heating and drying in an oven (temperature: 60°C, time: 4 minutes). The water-based adhesive used in this example was an aqueous solution containing an acetoacetyl group-containing polyvinyl alcohol resin (average polymerization degree: 1,200, saponification degree: 98.5 mol%, acetoacetylation degree: 5 mol%) and methylol melamine in a weight ratio of 3:1. The results are shown in Table 1.

[0092] <Comparative Example 1> A polarizing film and a pseudo-image display panel were produced and evaluated in the same manner as in Example 1, except that the first transparent protective film and the polarizing film, and the second transparent protective film and the polarizing film were bonded to each other on the opposite sides. The results are shown in Table 1.

[0093] <Comparative Example 2> A polarizing film and a pseudo-image display panel were produced and evaluated in the same manner as in Example 2, except that the first transparent protective film and the polarizing film, and the second transparent protective film and the polarizing film were bonded to each other on the opposite sides. The results are shown in Table 1.

[0094] [Table 1]

Claims

1. An image display panel comprising an image display cell, a first transparent protective film, an iodine-based polarizing film, and a second transparent protective film laminated in this order, The moisture permeability of the first transparent protective film is less than that of the second transparent protective film and is 200 g / m ２ ・24h) or less, The second transparent protective film has a moisture permeability of 250 g / (m 2 ·24 h) or more, The iodine-based polarizing film is represented by the general formula (1): b / a>1 (In the general formula (1), in an embodiment of the polarizing film in which the first transparent protective film is bonded to one side of the iodine-based polarizing film and the second transparent protective film is bonded to the other side of the iodine-based polarizing film, a is the 80 cm －１ From 130cm －１ b is the spectral area up to 80 cm 2 determined by Raman spectroscopy in a region of 1 μm to 1.5 μm from the surface of the polarizing film on the second transparent protective film side, －１ From 130cm －１ The spectral area ratio is expressed as: The image display panel is characterized in that the iodine-based polarizing film has an iodine complex (I 3 − ) on both sides.

2. The image display panel according to claim 1, characterized in that in the iodine-based polarizing film, the iodine concentration increases in the thickness direction from 1.5 μm or less from the surface of the polarizing film on the first transparent protective film side to 1.5 μm or less from the surface of the polarizing film on the second transparent protective film side.

3. 3. An image display device comprising: a front transparent member on said second transparent protective film side of said image display panel according to claim 1.

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