TWI690760B - Image display device and method of manufacturing the image display device - Google Patents

Abstract

The invention provides an image display device which can maintain excellent optical characteristics under a humidified environment and is prevented from fading. The image display device of the present invention includes: a display unit; a polarizing plate, which is arranged on at least one side of the display unit; and a sealing portion, which covers the peripheral end surface of the polarizing plate. The polarizing plate includes a polarizing film composed of a polyvinyl alcohol-based resin film containing iodine, and the moisture permeability of the sealing portion is 300 g/m ² /24hr or less. In one embodiment, the amount of fading after the image display device is maintained at 85°C and 85%RH for 120 hours is 100 μm or less.

Description

Image display device and method of manufacturing the image display device

The invention relates to an image display device and a manufacturing method of the image display device.

BACKGROUND OF THE INVENTION In image display devices (for example, liquid crystal display devices, organic EL display devices, quantum dot display devices), polarizing plates are often arranged on at least one side of the display unit due to the image formation method. However, the polarizing plate has a problem that the optical characteristics of the polarizing film, which can substantially determine the optical characteristics of the polarizing plate, decrease the durability under a humidified environment. More specifically, under a humidified environment, the polarizing performance at the end of the polarizing film will disappear, and as a result, the so-called fading phenomenon may occur in the image display device.

Prior Art Literature Patent Literature Patent Literature 1: Japanese Patent Laid-Open No. 2000-338329

SUMMARY OF THE INVENTION Problems to be Solved by the Invention The present invention was made to solve the above-mentioned problems, and its main object is to provide an image display device capable of maintaining excellent optical characteristics under a humidified environment and preventing discoloration and the image display device Simple manufacturing method.

Means for Solving the Problems The image display device of the present invention includes: a display unit; a polarizing plate, which is arranged on at least one side of the display unit; and a sealing portion, which covers the peripheral end surface of the polarizing plate. The polarizing plate includes a polarizing film made of a polyvinyl alcohol-based resin film containing iodine, and the moisture permeability of the sealing portion is 300 g/m ² /24hr or less. In one embodiment, the sealing portion covers the entire surface of the polarizing plate opposite to the display unit and the entire peripheral end surface. In one embodiment, the thickness of the sealing portion is 10 μm to 100 μm. In one embodiment, the sealing portion is composed of an adhesive composition. For example, the sealing portion is made of rubber-based adhesive. In one embodiment, the image display device further includes a cover glass, which is disposed on the opposite side of the polarizing plate from the display unit. In one embodiment, the amount of discoloration after the image display device is maintained at 85° C. and 85% RH for 120 hours is 100 μm or less. According to another aspect of the present invention, a method for manufacturing an image display device is provided. The manufacturing method includes the steps of: disposing a polarizing plate on one side of the display unit; and forming a sealing portion so as to cover the peripheral end surface of the polarizing plate. The polarizing plate includes a polarizing film made of a polyvinyl alcohol-based resin film containing iodine, and the moisture permeability of the sealing portion is 300 g/m ² /24hr or less. In one embodiment, the manufacturing method includes the steps of forming a sealing portion so as to cover the entire surface of the polarizing plate on the side opposite to the display unit and the entire peripheral end surface. In one embodiment, the above-described manufacturing method includes the steps of arranging a sheet composed of an adhesive composition to form a sealing portion. In one embodiment, the size of the sheet is larger than that of the polarizing plate, and the manufacturing method includes the step of covering the entire surface of the polarizing plate on the side opposite to the display unit and the entire peripheral end surface, The sheet is arranged to form a seal. In one embodiment, the manufacturing method further includes the step of arranging a cover glass on the opposite side of the polarizing plate from the display unit.

Effect of the Invention According to the present invention, by forming a sealing portion having a predetermined moisture permeability on the outer peripheral end surface of the polarizing plate, an image display device that can maintain excellent optical characteristics under a humidified environment and can prevent discoloration can be realized. In addition, according to the present invention, a simple manufacturing method of the image display device can be realized. In one embodiment, the manufacturing method includes the steps of using a sheet composed of an adhesive composition and having a size larger than a polarizing plate to cover the entire surface on the opposite side of the display unit and the entire peripheral end surface In this manner, the sheet is arranged to form a seal. With this embodiment, an image display device capable of maintaining excellent optical characteristics and preventing discoloration under a humidified environment can be manufactured very simply.

Forms for Carrying Out the Invention Embodiments of the present invention will be described below, but the present invention is not limited by these embodiments.

A. Overall structure of image display device The present invention can be applied to an image display device having a polarizing plate on at least one side of the display unit. Specific examples of such image display devices include liquid crystal display devices, organic electroluminescence (EL) display devices, and quantum dot display devices. The following is an example of an embodiment in which the present invention is applied to the viewing side portion of a liquid crystal display device. It is obvious to those skilled in the art that the present invention can also be applied to the back side portion of the liquid crystal display device, the organic EL display device, and the quantum dot display device in the same manner as the viewing side portion of the liquid crystal display device.

1 is a schematic partial cross-sectional view of an image display device according to an embodiment of the present invention, and more specifically, a schematic cross-sectional view of a viewing side portion of a liquid crystal display device. The liquid crystal display device 100 of FIG. 1 includes: a liquid crystal cell 10; a polarizing plate 20 disposed on the viewing side of the liquid crystal cell 10; and a sealing portion 30 for covering the peripheral end surface of the polarizing plate 20. The polarizing plate 20 includes a polarizing film 21. In the illustrated example, the protective film 22 is disposed on one side of the polarizing film 21 (the side opposite to the liquid crystal cell), but the protective film may be disposed on the liquid crystal cell side of the polarizing film depending on the purpose, etc. Configured on both sides. In practical use, an adhesive layer 50 is provided as the outermost layer on the liquid crystal cell 10 side of the polarizing plate 20, and the polarizing plate 10 is pasted on the liquid crystal cell 10 through the adhesive layer 50. The liquid crystal display device 100 is further representatively provided with a cover glass 40 that is disposed on the viewing side (the side opposite to the liquid crystal cell) of the polarizing plate 20. When a cover glass is provided, the protective film 22 may be omitted. The liquid crystal cell and the back side of the liquid crystal display device can adopt structures well known in the industry, so detailed descriptions of these are omitted here.

In the embodiment of the present invention, the polarizing film 21 is composed of a film of a polyvinyl alcohol resin containing iodine (hereinafter referred to as "PVA resin"). When the polarizing film contains iodine, the effect of providing the sealing part becomes remarkable. The thickness of the polarizing film is typically 8 μm or less. When the polarizing film contains iodine, and its thickness is quite thin as described above, since the density of iodine in the polarizing film will increase, and the stability of iodine will be easily reduced by humidification, the effect of providing the sealing part will become more significant .

In addition, in the embodiment of the present invention, the moisture permeability of the sealing portion is 300 g/m ² /24hr or less. The sealing portion 30 only needs to cover the surrounding end surface of the polarizing plate 20 (that is, the polarizing film 21 and the protective film 22 ), and the surrounding end surface of the adhesive layer 50 may be entirely or partially covered, or may not be covered. In the illustrated example, the sealing portion 30 covers the peripheral end surfaces of the polarizing plate 20 and the adhesive layer 50. In addition, the sealing portion 30 may cover only the peripheral end face of the polarizing plate 20, or may cover portions other than the peripheral end face together with the peripheral end face. As shown in the example above, the sealing portion 30 covers the entire surface of the polarizer's peripheral end surface, and also covers the entire surface of the polarizer on the side opposite to the liquid crystal cell 10. In addition, the sealing portion 30 only needs to cover the peripheral end face of the polarizing plate 20 and seal the peripheral end face, and does not need to be in close contact with the peripheral end face.

The amount of discoloration of the liquid crystal display device 100 (substantially the polarizing plate 20) after being maintained at 85°C and 85%RH for 120 hours is preferably 100 μm or less, preferably 50 μm or less, more preferably 30 μm or less, and particularly 25 μm or less good. The lower limit of the amount of discoloration is preferably 0, and 5 μm in one embodiment. The amount of discoloration can be calculated as follows: a test piece of a predetermined size is cut out from the polarizing plate (or polarizing film), and the test piece is formed into two sides opposite to the direction perpendicular to the extending direction and the extending direction, respectively. In addition, the extension direction corresponds to the absorption axis direction of the polarizing film. The extending direction may correspond to, for example, the long-side direction (transport direction (MD direction)) of the polarizing plate. Next, the test piece was attached to the glass plate with an adhesive to prepare it as a replacement for the liquid crystal display device. The liquid crystal display device was placed in an oven at 85°C and 85%RH for 120 hours for humidification. After disposing the humidified test piece and the standard polarizing plate in a state of orthogonal polarization, the discolored state of the end of the humidified test piece was observed with a microscope. Specifically, the amount of discoloration (fading amount: μm) from the end of the test piece (polarizing plate or polarizing film) is measured. As shown in FIG. 2, among the amount of fading a from the end in the extending direction and the amount of fading b from the end in the direction perpendicular to the extending direction, the greater the numerical value is the amount of fading. In addition, the polarized characteristics of the faded area are significantly lower, and the function of the polarizing plate cannot be substantially achieved. Therefore, the smaller the amount of discoloration, the better.

The example in the drawings illustrates the case where the structure of the polarizing plate and the sealing portion of the present invention is applied to the viewing side portion of the liquid crystal display device, but as described above, the structure can also be applied to the back side of the liquid crystal display device It can also be applied to both the viewing side part and the back side part of the liquid crystal display device, the organic EL display device, and the quantum dot display device. In addition, the organic EL display device and the quantum dot display device can also adopt a well-known structure in the industry, so a detailed description is omitted here.

The optical films and optical members used in the image display device of the present invention will be described below.

B. Polarizing plate B-1. Polarizing film As described above, the polarizing film 21 is composed of a PVA-based resin film containing iodine.

As the PVA-based resin used to form the above-mentioned PVA-based resin film, any suitable resin can be used. Examples thereof include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer can be obtained by saponifying the ethylene-vinyl acetate copolymer. The saponification degree of the PVA resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, and more preferably 99.0 mol% to 99.93 mol%. The degree of saponification is determined in accordance with JIS K 6726-1994. By using the saponification degree PVA-based resin, a polarizing film excellent in durability can be obtained. When the degree of saponification is too high, there is a risk of gelation.

The average degree of polymerization of the PVA-based resin can be appropriately selected according to the purpose. The average polymerization degree is usually 1000 to 10000, preferably 1200 to 5000, and more preferably 1500 to 4500. In addition, the average degree of polymerization can be obtained in accordance with JIS K 6726-1994.

As described above, the polarizing film contains iodine. The polarizing film is essentially a PVA-based resin film with iodine adsorbed and aligned. The iodine concentration in the PVA-based resin film is, for example, 5.0% by weight to 12.0% by weight. In addition, the boric acid concentration in the PVA-based resin film is, for example, 12% by weight to 25% by weight.

As described above, the thickness of the PVA-based resin film (polarizing film) is 8 μm or less, preferably 7 μm or less, and more preferably 6 μm or less. On the other hand, the thickness of the PVA-based resin film is preferably 1.0 μm or more, and more preferably 2.0 μm or more.

The polarizing film preferably exhibits absorption dichroism at any wavelength from 380 nm to 780 nm. The single transmittance of the polarizing film should be 40.0%~46.0%, more preferably 41.0%~45.0%. The polarization degree of the polarizing film is preferably 99.9% or more, preferably 99.95% or more, and more preferably 99.98% or more. When the polarizing plate is applied to a reflective liquid crystal display device or an organic EL display device, the polarization degree of the polarizing film is preferably 90% or more, preferably 93% or more, and more preferably 95% or more. As described above, by providing a sealing portion for covering the peripheral end surfaces of the polarizing film and the protective film, both the excellent optical characteristics (a good balance between the transmittance of the monomer and the degree of polarization) and the excellent durability (even in the The excellent optical characteristics can still be maintained in a wet environment).

B-2. Protective film The protective film 22 is composed of any suitable film that can be used as a protective film for the polarizing film. Specific examples of the material of the main component of the film include cellulose resins such as triacetyl cellulose (TAC), polyester-based, polyvinyl alcohol-based, polycarbonate-based, polyamide-based, and polyamide-based Transparent resins such as imine-based, polyether-based, poly-based, polystyrene-based, polynorbornene-based, polyolefin-based, (meth)acrylic, and acetate-based. In addition, thermosetting resins such as (meth)acrylic system, urethane system, (meth)acrylate urethane system, epoxy system, and polysiloxane system, ultraviolet curing resin, etc. may also be mentioned. Other examples include glassy polymers such as siloxane-based polymers. Moreover, the polymer film described in Japanese Patent Laid-Open No. 2001-343529 (WO01/37007) can also be used. As the material of the film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted amide imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used And, for example, a resin composition having an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer. The polymer film may be, for example, an extruded product of the above resin composition.

In the embodiment of the present invention, the resin substrate used in the manufacture of the polarizing plate (described later in item E) can be used as a protective film as it is.

As shown in the example of the figure, when the polarizing plate is disposed on the viewing side of the display unit and the protective film is disposed on the viewing side of the polarizing film, the protective film may be subjected to hard coating treatment, anti-reflection treatment, and anti-reflection treatment as required. Surface treatment such as adhesion treatment and anti-glare treatment.

As long as the effect of the present invention is obtained, the thickness of the protective film can be any arbitrary and appropriate thickness. The thickness of the protective film is, for example, 20 μm to 40 μm, preferably 25 μm to 35 μm. In addition, when surface treatment is performed, the thickness of the protective film includes the thickness of the surface treatment layer.

When another protective film (inner protective film) is disposed between the polarizing film 21 and the adhesive layer 50, the inner protective film is preferably optically isotropic. In this specification, "optically isotropic" means that the in-plane retardation Re (550) is 0 nm to 10 nm, and the thickness direction retardation Rth (550) is -10 nm to +10 nm. The Re (550) of the inner protective film is preferably 0nm~8nm, preferably 0nm~6nm, and more preferably 0nm~3nm. The Rth (550) of the inner protective film is preferably -8nm~+8nm, preferably -6nm~+6nm, and more preferably -3nm~+3nm. In addition, "Re(550)" is the in-plane phase difference measured at 23°C with light having a wavelength of 550 nm. Re(550) can be obtained by the formula: Re(550)=(nx-ny)×d when the thickness of the layer (thin film) is d (nm). In addition, "Rth(550)" is a phase difference in the thickness direction measured at 23°C with light having a wavelength of 550 nm. Rth(550) can be obtained by the formula: Rth(550)=(nx-nz)×d when the thickness of the layer (thin film) is d (nm).

C. Sealing portion As described above, the sealing portion 30 covers the peripheral end surface of the polarizing plate 20 while maintaining the optical characteristics of the polarizing plate under a humidified environment, thereby improving the durability of the polarizing plate. Therefore, the sealing part should have a barrier function. In this specification, "having a barrier function" means that the amount of transmission of oxygen and/or water vapor entering the polarizing film can be controlled to substantially isolate the polarizing film from its equivalent.

As described above, the sealing portion has barrier properties, which means that it has barrier properties against moisture and gas (for example, oxygen). The water vapor transmission rate (moisture permeability) of the sealing part at 40°C and 90%RH is preferably 300g/m ² /24hr or less, preferably 100g/m ² /24hr or less, 70g/m ² /24hr The following is more preferable, and 40 g/m ² /24hr or less is particularly preferable. The lower limit of moisture permeability is, for example, 0.01 g/m ² /24hr, and it is better if the detection limit is not reached. As long as the moisture permeability of the sealing portion is within the above-mentioned range, the polarizing film can be well protected from contact with moisture and oxygen in the air. In addition, the moisture permeability can be measured according to JIS Z0208.

As long as the above-mentioned characteristics are satisfied, the sealing portion may be composed of any appropriate material. Representative materials include adhesive compositions. The "adhesive composition" in this specification is intended to include both an adhesive (adhesive composition) and an adhesive composition.

Examples of the adhesive composition include a rubber-based adhesive composition using a rubber-based polymer as a base polymer.

Examples of the rubber-based polymer include: a conjugated diene polymer obtained by polymerizing a conjugated diene compound, a conjugated diene copolymer obtained by polymerizing two or more conjugated diene compounds, and a conjugated polymer. Conjugated diene copolymer obtained by copolymerization of a diene compound and an aromatic vinyl compound, and their hydrides.

The conjugated diene compound is not particularly limited as long as it is a monomer having a polymerizable conjugated diene. Specific examples of conjugated diene compounds include: 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 3 -Methyl-1,3-pentadiene, 1,3-heptadiene, 1,3-hexadiene. Among these, 1,3-butadiene and isoprene are preferred from the viewpoint of industrial availability. The conjugated diene compound may be used alone or in combination.

The aromatic vinyl compound is not particularly limited as long as it is a monomer having an aromatic vinyl structure copolymerizable with the conjugated diene compound. Specific examples of the aromatic vinyl compound include styrene, p-methylstyrene, α-methylstyrene, vinylethylbenzene, vinylxylene, vinylnaphthalene, and diphenylethylene. Among these, styrene is preferred from the viewpoint of ease of obtaining in industry. The aromatic vinyl compound may be used alone or in combination.

The diene copolymer may be a random copolymer or a block copolymer. In addition, a diene copolymer can be obtained by copolymerizing compounds other than the conjugated diene compound and aromatic vinyl compound.

A conjugated diene copolymer obtained by copolymerizing a conjugated diene compound and an aromatic vinyl compound, the molar ratio of the conjugated diene compound and the aromatic vinyl compound is preferably a conjugated diene compound/aromatic vinyl Base compound = 10/90~90/10 (mol%).

Specific examples of such conjugated diene-based (co)polymers include: butadiene rubber (BR), isoprene rubber (IR), styrene-butadiene copolymer (SBR), butadiene Enene-isoprene-styrene random copolymer, isoprene-styrene random copolymer, styrene-isoprene block copolymer (SIS), butadiene-styrene copolymer, Styrene-ethylene-butadiene block copolymer (SEBS), acrylonitrile-butadiene rubber (NBR). These can be used alone or in combination. Among these, isoprene-styrene copolymer is preferred. In addition, these hydrides can also be applied.

In addition to conjugated diene (co)polymers, rubber-based polymers can also be used isobutylene (IB), styrene-isobutylene-styrene block copolymer (SIBS), styrene-ethylene propylene copolymer-benzene Ethylene block copolymer, etc. The rubber-based polymer may be used alone or in combination.

The rubber-based polymer usable in the present invention preferably contains 50% by weight or more of the above-mentioned conjugated diene-based (co)polymer in the entire rubber-based polymer, and preferably contains 70% by weight or more, 80% by weight The above is even better, and more than 90% by weight is particularly good. The upper limit of the content of the conjugated diene-based (co)polymer is not particularly limited, and may be 100% by weight (that is, a rubber-based polymer composed only of the conjugated diene-based (co)polymer).

As described above, the adhesive composition system contains the rubber-based polymer as the base polymer. The content of the rubber-based polymer in the adhesive composition is preferably 40% by weight or more, preferably 50% by weight or more, and more preferably 60% by weight or more. The upper limit of the content of the rubber-based polymer is not particularly limited, and is, for example, 90% by weight or less.

In addition to the rubber-based polymer, the adhesive composition may further contain arbitrary and appropriate additives. Specific examples of additives include: crosslinking agents (such as polyisocyanates, epoxy compounds, alkyl etherified melamine compounds, etc.), tackifiers (such as rosin derivative resins, polyterpene resins, petroleum resins, fat-soluble phenol resins) , Vinyl toluene resin, etc.), plasticizers, fillers (such as layered silicate, clay materials, etc.), antioxidants. The type, combination and amount of additives added to the adhesive composition can be appropriately set according to the purpose. The additive content (total amount) in the adhesive composition is preferably 60% by weight or less, preferably 50% by weight or less, and more preferably 40% by weight or less.

Representative examples of the adhesive composition include active energy ray-curable adhesive compositions and thermosetting adhesive compositions. Examples of the active energy ray hardening type adhesive composition include light (eg, ultraviolet) hardening type adhesive composition and electron beam hardening type adhesive composition. The active energy ray-curable adhesive composition can be selected from radical curing type, cation curing type, anion curing type, etc. as needed, and can also be used in appropriate combination, for example, a mixture type of radical curing type and cation curing type.

In one embodiment, the adhesive composition is an ultraviolet curing adhesive composition. For the ultraviolet curable adhesive composition, for example, the adhesive composition described in Japanese Patent Laid-Open No. 2013-227419 can be applied. In this specification, the description of this publication is used as a reference.

The thickness of the sealing part is, for example, about 10 μm to 200 μm, preferably 15 μm to 100 μm, preferably 20 μm to 70 μm, and more preferably 25 μm to 50 μm. Unless otherwise specified in this specification, the "thickness of the sealing portion" means the thickness in the direction extending outward from the peripheral ends of the polarizing film and the protective film. In addition, when the sealing portion also covers the surface of the polarizing plate opposite to the liquid crystal cell, the thickness of the sealing portion of the surface is, for example, about 10 μm to 200 μm, preferably 15 μm to 100 μm, preferably 20 μm to 70 μm , 25μm~50μm is better.

D. Adhesive layer The adhesive layer 50 is composed of arbitrary and appropriate adhesives. Representative examples of the adhesive include acrylic adhesives. The thickness of the adhesive layer is, for example, 20 μm to 100 μm.

E. Manufacturing method of the image display device The manufacturing method of the image display device of the present invention includes the following steps: disposing a polarizing plate on one side of the display unit; forming a sealing portion in such a manner as to cover the peripheral end surface of the polarizing plate; and, if necessary, polarizing A cover glass is arranged on the opposite side of the panel from the display unit. Hereinafter, as a representative example of the manufacturing method of the image display device of the present invention, an embodiment including a step of arranging a polarizing plate on the viewing side portion of the liquid crystal display device and forming a sealing portion on the peripheral end surface of the polarizing plate will be described. This embodiment corresponds to the method of manufacturing the liquid crystal display device described in the above item A.

E-1. Manufacturing a polarizing film The manufacturing method of a polarizing plate according to an embodiment of the present invention typically includes the following steps: forming a PVA-based resin layer on one side of a resin substrate; and, the resin substrate and the PVA-based resin layer The laminate of the resin layer is stretched and dyed to form a polarizing film of the PVA-based resin layer. In another embodiment, a laminate of a resin base material and a PVA-based resin film may be prepared, and the laminate may be dyed to form a polarizing film from the PVA-based resin film. In still another embodiment, a single PVA-based resin film may be stretched and dyed to form a polarizing film from the PVA-based resin film. As a representative example, a manufacturing method including a step of forming a PVA-based resin layer on one side of a resin substrate will be described below.

E-1-1. Formation of PVA-based resin layer Any and appropriate method can be used to form the PVA-based resin layer. It is preferable to apply a coating liquid containing a PVA-based resin on a resin substrate and dry it to form a PVA-based resin layer.

As the forming material of the resin base material, any suitable thermoplastic resin can be used. Examples of the thermoplastic resin include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, and polycarbonate resins. , And other copolymer resins. Among these, norbornene-based resins and amorphous polyethylene terephthalate-based resins are more desirable.

In one embodiment, an amorphous (uncrystallized) polyethylene terephthalate resin is preferably used. Among them, the use of amorphous (difficult to crystallize) polyethylene terephthalate resins is particularly preferred. Specific examples of the amorphous polyethylene terephthalate-based resin include a copolymer further containing isophthalic acid as a dicarboxylic acid, or a copolymer containing cyclohexane dimethanol as a glycol.

When the water extension method is used in the extension described later, the resin base material absorbs water, and the water can function as a plasticizer for plasticization. As a result, the elongation stress can be greatly reduced, and the elongation can be extended at a high rate, so that superior elongation can be obtained than in the air. As a result, a polarizing film having excellent optical characteristics can be produced. In one embodiment, the water absorption rate of the resin substrate is preferably 0.2% or more, and more preferably 0.3% or more. On the other hand, the water absorption rate of the resin substrate is preferably 3.0% or less, and more preferably 1.0% or less. By using such a resin base material, it is possible to prevent defects such as deterioration of the appearance of the polarizing film produced due to a significant decrease in dimensional stability during manufacturing. It can prevent the base material from breaking when extending in water, or the PVA-based resin layer peeling off from the resin base material. In addition, the water absorption rate of the resin base material can be adjusted by, for example, introducing a modified group into the forming material. The water absorption rate is a value determined in accordance with JIS K 7209.

The glass transition temperature (Tg) of the resin substrate is preferably 170°C or lower. By using such a resin base material, the crystallization of the PVA-based resin layer can be suppressed, and the extensibility of the laminate can be sufficiently ensured. In addition, considering that the resin base material is plasticized with water and can be easily extended in water, it is more preferably 120°C or lower. In one embodiment, the glass transition temperature of the resin substrate is preferably 60°C or higher. By using such a resin base material, it is possible to prevent defects such as deformation of the resin base material (e.g., unevenness, dents, wrinkles, etc.) when coating and drying the coating solution containing the PVA-based resin, which is good To produce a laminate. In addition, the stretching of the PVA-based resin layer can be performed favorably at an appropriate temperature (for example, about 60°C). In another embodiment, when coating and drying a coating liquid containing a PVA-based resin, the glass transition temperature may be lower than 60°C as long as the resin substrate is not deformed. In addition, for example, the glass transition temperature of the resin base material can be adjusted by heating using a crystallization material that can introduce a modified group into the forming material. The glass transition temperature (Tg) is a value determined in accordance with JIS K 7121.

The thickness of the resin substrate before extension is preferably 20 μm to 300 μm, more preferably 50 μm to 200 μm. If it is less than 20 μm, it may be difficult to form a PVA-based resin layer. If it exceeds 300 μm, for example, the resin substrate may take a long time to absorb water when stretched in water, which may cause excessive load on the stretch.

The above-mentioned coating liquid represents a solution in which the PVA-based resin has been dissolved in a solvent. Examples of the solvent include polyhydric alcohols such as water, dimethylsulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, and trimethylolpropane. Ethylenediamine, diethylenetriamine and other amines. These can be used alone or in combination of two or more. Among these, water is better. The concentration of the PVA resin in the solution is preferably 3-20 parts by weight relative to 100 parts by weight of the solvent. As long as it is the above-mentioned resin concentration, a uniform coating film adhered to the resin substrate can be formed.

Additives can also be incorporated in the coating solution. Examples of additives include plasticizers and surfactants. Examples of plasticizers include polyhydric alcohols such as ethylene glycol and glycerin. The surfactant may, for example, be a nonionic surfactant. These can be used to further improve the uniformity, dyeability, and extensibility of the resulting PVA-based resin layer. In addition, additives can be mentioned as easily accessible ingredients. By using the easy-access component, the adhesion between the resin substrate and the PVA-based resin layer can be improved. As a result, defects such as peeling of the PVA-based resin layer from the base material can be suppressed, and dyeing and water stretching described below can be performed favorably. For easy access to the ingredients, for example, modified PVA such as acetyl-based modified PVA can be used.

The method for applying the coating liquid can be any appropriate method. For example, a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, a doctor blade coating method (comma coating method, etc.), etc. are mentioned.

The coating and drying temperature of the coating liquid is preferably 50°C or higher.

Before forming the PVA-based resin layer, the resin substrate may be subjected to surface treatment (eg, corona treatment, etc.), or an easy adhesion layer may be formed on the resin substrate. By performing the treatment, the adhesion between the resin base material and the PVA-based resin layer can be improved.

The thickness of the PVA-based resin layer (before extension) is preferably 3 μm to 20 μm.

E-1-2. Extension The extension method of the laminate can be any and appropriate method. Specifically, it may be a fixed-end extension or a free-end extension (for example, a method of uniaxially extending a laminate between rollers having different peripheral speeds). It is appropriate to extend the free end.

The extending direction of the laminate can be set appropriately. In one embodiment, it extends along the longitudinal direction of the elongated laminate. At this time, a method of extending the laminated body between rollers having different peripheral speeds is adopted as a representative. In another embodiment, it extends along the width direction of the elongated laminate. At this time, the method of stretching with a tenter stretching machine is used on the representative.

The extension method is not particularly limited, and an air extension method or an underwater extension method may be used. It is suitable to extend in water. It can be stretched at a temperature lower than the glass transition temperature of the above resin base material or PVA-based resin layer (representing the upper temperature of about 80°C) by water stretching, which can suppress the crystallization of the PVA-based resin layer To extend at a high magnification. As a result, a polarizing film having excellent optical characteristics can be produced.

The extension of the laminate can be performed in one stage or in multiple stages. When performing in multiple stages, for example, the above-mentioned free-end extension and fixed-end extension may be combined, or the above-mentioned underwater extension method and air extension method may be combined. When performing in multiple stages, the stretching magnification (maximum stretching magnification) of the laminate to be described later is the product of the stretching magnification in each stage.

The stretching temperature of the laminate can be set to an arbitrary and appropriate value depending on the forming material of the resin base material, the stretching method, and the like. When using the air stretching method, the stretching temperature is preferably above the glass transition temperature (Tg) of the resin substrate, preferably above the glass transition temperature (Tg) of the resin substrate + 10°C, and particularly preferably above Tg + 15°C . On the other hand, the elongation temperature of the laminate is preferably 170°C or lower. By stretching at the above-mentioned temperature, the rapid progress of crystallization of the PVA-based resin can be suppressed, and thus the defects caused by the crystallization can be suppressed (for example, the orientation of the PVA-based resin layer is hindered by stretching).

When the underwater extension method is adopted, the liquid temperature of the extension bath is above 60°C, preferably 65°C to 85°C, and more preferably 65°C to 75°C. As long as it is within the above temperature, the PVA-based resin layer can be suppressed from dissolving, and at the same time, it can be stretched at a high rate. Specifically, as described above, the relationship between the formation of the PVA-based resin layer and the glass transition temperature (Tg) of the resin substrate is preferably 60° C. or higher. At this time, if the elongation temperature is lower than 60°C, even if the resin base material is considered to be plasticized with water, there is a fear that the elongation will not be good. On the other hand, the higher the temperature of the stretching bath, the higher the solubility of the PVA-based resin layer, and it may be impossible to obtain excellent optical characteristics. The immersion time of the laminate in the extension bath is preferably 15 seconds to 5 minutes.

When the underwater stretching method is adopted, the method of immersing the laminate in a boric acid aqueous solution for stretching is preferable (boric acid water stretching). By using a boric acid aqueous solution as an extension bath, the PVA-based resin layer can be given rigidity that can withstand the tension received during extension and water resistance that is insoluble in water. Specifically, boric acid generates tetrahydroxyboric acid anions in the aqueous solution and can be cross-linked with the PVA-based resin by hydrogen bonding. As a result, it is possible to impart rigidity and water resistance to the PVA-based resin layer and perform good stretching, thereby producing a polarizing film having excellent optical characteristics.

The aforementioned boric acid aqueous solution is preferably obtained by dissolving boric acid and/or borate in a solvent, that is, water. In the present invention, the boric acid concentration is 4.5% by weight or less, preferably 2.0% by weight to 4.5% by weight, and more preferably 2.5% by weight to 4.0% by weight. In addition to boric acid or borate, an aqueous solution obtained by dissolving boron compounds such as borax, glyoxal, glutaraldehyde and the like in a solvent can also be used.

If a dichroic substance (represented by iodine) is adsorbed on the PVA-based resin layer by dyeing described later, it is preferable to mix the iodide in the above-mentioned extension bath (boric acid aqueous solution). By blending iodide, the elution of iodine that has been adsorbed on the PVA-based resin layer can be suppressed. Examples of the iodine compound include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Among these, potassium iodide is preferred. The concentration of iodide is preferably 0.05 to 15 parts by weight, more preferably 0.5 to 8 parts by weight relative to 100 parts by weight of water.

The stretching magnification (maximum stretching magnification) of the laminate is preferably 5.0 times or more relative to the original length of the laminate. The high extension ratio can be achieved, for example, by using an underwater extension method (boric acid underwater extension). In addition, the "maximum elongation ratio" in this specification means the elongation ratio before the laminate is to be broken, and it is a value that is 0.2 lower than its value after confirming the elongation ratio of the laminate to break.

In one embodiment, the laminate is stretched in air at a high temperature (for example, 95° C. or higher), and then the boric acid water stretch and the dyeing described below are performed. Since this aerial extension can be defined as a preparatory or auxiliary extension relative to the boric acid water extension, it is referred to as "air-assisted extension" hereinafter.

By combining air-assisted extension, the laminate can sometimes be extended at a higher magnification. As a result, a polarizing film having more excellent optical characteristics (such as polarization degree) can be produced. For example, when using polyethylene terephthalate-based resin as the above resin base material, the combined air-assisted extension and boric acid underwater extension for extension can be more effective in suppressing the resin than for extension by only boric acid underwater extension. The alignment of the substrate is extended at the same time. As the alignment of the resin substrate is increased, its extensional tension will increase, making it difficult to achieve stable extension or breakage. Therefore, it is possible to extend the laminate while suppressing the alignment of the resin base material while extending the laminate at a higher rate.

In addition, the combined air-assisted extension can improve the alignment of the PVA-based resin, and thus the alignment of the PVA-based resin can be improved after the boric acid water extension. Specifically, we speculate that by increasing the alignment of the PVA-based resin in advance by air-assisted stretching, the PVA-based resin can be easily cross-linked with boric acid when it is stretched in boric acid water, and the boric acid becomes a chain link point. It can be extended in boric acid water and can still improve the alignment of PVA resin. As a result, a polarizing film having excellent optical characteristics (such as polarization degree) can be produced.

The extension magnification of air-assisted extension should be less than 3.5 times. The extension temperature of the air-assisted extension is preferably higher than the glass transition temperature of the PVA resin. The extension temperature should be 95℃~150℃. In addition, the maximum extension ratio when combining the air-assisted extension and the above-mentioned boric acid underwater extension is preferably 5.0 times or more relative to the original length of the laminate, preferably 5.5 times or more, and more preferably 6.0 times or more.

E-1-3. Dyeing The dyeing of the PVA-based resin layer is performed by adsorbing iodine on the PVA-based resin layer. 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 spraying the dyeing solution to the PVA Method on the resin layer. The method of immersing the PVA-based resin layer (laminate) in the dyeing solution is preferably used. This is because it can adsorb iodine well.

The above dyeing solution is preferably an aqueous iodine solution. The blending amount of iodine is preferably 0.1 to 0.5 parts by weight relative to 100 parts by weight of water. In order to improve the solubility of iodine in water, it is appropriate to mix iodide in the iodine aqueous solution. Specific examples of iodide are as described above. The blending amount of iodide is preferably 0.02 to 20 parts by weight, and more preferably 0.1 to 10 parts by weight relative to 100 parts by weight of water. In order to suppress the dissolution of the PVA-based resin, the temperature of the dyeing liquid during dyeing is preferably 20°C to 50°C. When immersing the PVA-based resin layer in the dyeing solution, in order to ensure the transmittance of the PVA-based resin layer, the immersion time is preferably 5 seconds to 5 minutes. In addition, the dyeing conditions (concentration, liquid temperature, immersion time) can be set so that the polarization degree or the monomer transmittance of the polarizing film finally obtained is within a predetermined range. In one embodiment, the immersion time is set so that the polarization degree of the obtained polarizing film becomes 99.98% or more. In another embodiment, the immersion time is set so that the monomer transmittance of the obtained polarizing film becomes 40.0% to 42.5%.

The dyeing treatment can be performed at any appropriate time. When performing the above-mentioned underwater extension, it is appropriate to perform it before underwater extension.

E-1-4. Other treatments In addition to stretching and dyeing, the PVA-based resin layer (laminate) may be appropriately subjected to a treatment for making it into a polarizing film. Examples of the treatment for forming the polarizing film include insolubilization treatment, cross-linking treatment, washing treatment, and drying treatment. In addition, the number and order of such treatments are not particularly limited.

The above-mentioned insolubilization treatment is typically performed by immersing a PVA-based resin layer (laminate) in an aqueous solution of boric acid. By performing the insolubilization treatment, the PVA-based resin layer can be given water resistance. The concentration of the boric acid aqueous solution is preferably 1 part by weight to 4 parts by weight relative to 100 parts by weight of water. The liquid temperature of the insoluble bath (boric acid aqueous solution) is preferably 20°C to 50°C. The insolubilization treatment is preferably carried out before the above water extension or the above dyeing treatment.

The above cross-linking treatment is typically performed by immersing the PVA-based resin layer (laminate) in an aqueous solution of boric acid. By performing the cross-linking treatment, the PVA-based resin layer can be given water resistance. The concentration of the boric acid aqueous solution is preferably 1 part by weight to 5 parts by weight relative to 100 parts by weight of water. In addition, when the cross-linking treatment is performed after the above-mentioned dyeing treatment, it is preferable to further blend iodide. By blending iodide, the elution of iodine that has been adsorbed on the PVA-based resin layer can be suppressed. The blending amount of iodide is preferably 1 to 5 parts by weight relative to 100 parts by weight of water. Specific examples of iodide are as described above. The liquid temperature of the cross-linking bath (boric acid aqueous solution) is preferably 20°C to 60°C. The cross-linking treatment is preferably carried out before the above water extension. The preferred embodiment is to perform air stretching, dyeing and cross-linking in order.

The above cleaning treatment is typically performed by immersing the PVA-based resin layer (laminate) in an aqueous potassium iodide solution. The drying temperature of the above drying treatment is preferably 30°C to 100°C.

Through the above procedure, a polarizing film is formed on the resin substrate.

E-2. Arrangement of polarizing plate In one embodiment, the laminate of the resin base material and polarizing film obtained in the above item E-1 is arranged as the polarizing plate 20 on the viewing side of the liquid crystal cell 10. In another embodiment, the protective film is attached to the surface of the polarizing film of the laminate of the resin substrate (protective film) and the polarizing film (for convenience, this protective film is referred to as another protective film). The obtained resin substrate (protective film)/polarizing film/another protective film laminate is disposed on the viewing side of the liquid crystal cell 10 as the polarizing plate 20. In still another embodiment, after the protective film is bonded to the surface of the polarizing film of the laminate of the resin base material and the polarizing film, the resin base material is subsequently peeled off and removed. The obtained polarizing film/protective film laminate is disposed as the polarizing plate 20 on the viewing side of the liquid crystal cell 10. In yet another embodiment, another protective film is bonded to the polarizing film surface (resin substrate peeling surface) of the polarizing film/protective film laminate, and the protective film/polarizing film/another protective film is laminated The body is arranged as the polarizing plate 20 on the viewing side of the liquid crystal cell 10. Representatively, as shown in FIG. 3( a ), the polarizing plate 20 is bonded to the liquid crystal cell 10 (substantially the viewing side substrate of the liquid crystal cell) through the adhesive layer 50. In addition, as shown in FIG. 3( a ), the size of the polarizing plate 20 is typically smaller than the size of the liquid crystal cell 10.

E-3. Formation of sealing portion Next, the sealing portion is formed so as to cover the peripheral end surface of the polarizing plate 20 disposed in the liquid crystal cell 10. The following describes the case where the sealing portion is formed of the adhesive composition.

Representatively, the sealing portion is formed by disposing the adhesive composition to cover the outer peripheral end surface of the laminate. The sealing portion can be formed by applying a liquid (before hardening) adhesive composition to a predetermined position and hardening it, or by disposing a sheet-like adhesive composition (typically, bonding) to Formed at a predetermined location. In one embodiment, as shown in FIG. 3(b), a sheet having a size larger than the polarizing plate is arranged to extend from the outer periphery of the polarizing plate. It should be configured to extend from all four sides forming the outer periphery of the polarizing plate. The length of the extended portion of the sheet can be appropriately set so as to cover the entire end surface of the polarizing plate. By adjusting the softness (for example, the coefficient of elasticity) of the sheet, the extended portion of the sheet can sag under its own weight to cover the peripheral end face of the polarizing plate. Alternatively, the extension portion of the sheet may be bent to cover the peripheral end face of the polarizing plate by any appropriate operation. As shown in FIG. 3(c), the sealing portion is formed by adopting the above structure, and the sealing portion covers the entire surface of the polarizing plate on the side opposite to the display unit and the entire surface of the peripheral end surface.

The cover glass 40 is disposed on the opposite side of the polarizing plate 20 from the liquid crystal cell 10 as needed. As shown in FIG. 3(d), the cover glass 40 is attached to the polarizing plate 20 through the sealing portion 30 covering the surface of the polarizing plate 20 on the side opposite to the liquid crystal cell 10.

On the back side of the liquid crystal cell 10, a back side polarizing plate, a back side optical member, and a backlight unit (if any) are laminated through a program well known in the industry. The liquid crystal display device can be obtained through the above procedure.

The above embodiment is an example. The same procedure can also be applied to the back side portion of the liquid crystal display device; or the well-known procedure in the industry can be used for the viewing side portion of the liquid crystal display device, and the same procedure can be used only for the back side portion of the liquid crystal display device; for the organic EL display device The same program can also be used on the same; the same program can also be used on the quantum dot display device. Examples

Hereinafter, the present invention will be specifically described with examples, but the present invention is not limited by these examples. In addition, the measuring method of each characteristic is as follows.

(1) Thickness was measured using a digital micrometer (KC-351C manufactured by Anritsu Corporation). (2) Moisture permeability The adhesive composition prepared in Examples and Comparative Examples was used to form an adhesive sheet with a thickness of 50 μm according to the method described in Examples. Next, after peeling off one of the release liners of the adhesive sheet to expose the adhesive surface, the adhesive sheet was stuck to the triacetyl cellulose film (TAC film, thickness: 25 μm, made by Konica Minolta (share)) through the adhesive surface On, and cut into a round shape of 10cmΦ. Finally, the other release liner was peeled off to obtain a sample for measurement. And the obtained measurement sample was measured for the water vapor permeability (water vapor transmission rate) according to the water vapor permeability test method (cup method, based on JIS Z 0208). In addition, the measurement conditions are as follows. In addition, a constant temperature and humidity tank was used for the measurement. Measurement temperature: 40°C Relative humidity: 92% Measurement time: 24 hours (3) Discoloration amount A test piece (50mm×50mm) was cut out from the polarizing plates used in Examples and Comparative Examples, and the test piece was attached with an adhesive Combined with the alkali-free glass plate, the test piece is formed on two sides opposite to the direction perpendicular to the extension direction and the extension direction. Here, the sealing portions were formed in the same manner as the manufacturing procedures of the liquid crystal display devices of the examples and the comparative examples, respectively, to produce liquid crystal display device substitutes. It was placed in an oven at 85°C and 85%RH for 120 hours for humidification, and then it was placed in a state of orthogonal polarization with a standard polarizer, and the discoloration state of the end of the polarized film after humidification was investigated with a microscope. Specifically, the size of the discoloration from the end of the polarizing film (fading amount: μm) was measured. The MX61L manufactured by Olympus was used as the microscope, and the amount of discoloration was measured from the image taken at a magnification of 10 times. As shown in FIG. 2, among the amount of fading a from the end in the extending direction and the amount of fading b from the end in the direction perpendicular to the extending direction, the greater the numerical value is the amount of fading. (4) Fading, light leakage, and white fogging After forming an acrylic adhesive layer (thickness: 20 μm) on the polarizing film surface of the polarizing plates obtained in Examples and Comparative Examples, it was cut into 50 mm × 50 mm and transmitted The adhesive layer is attached to the surface of 100mm×100mm alkali-free glass. Next, the sheet-like adhesives used in the examples and the comparative examples were placed on the surface of the polarizing plate opposite to the alkali-free glass. At this time, the sheet is arranged to extend from all four sides constituting the outer periphery of the polarizing plate. The length of the four extensions is 5mm each. The sheet sags by its own weight, directly adheres to the glass, and covers the outer peripheral end face of the polarizing plate to be sealed. Through the above procedure, a sealing portion covering the entire surface of the polarizing plate and the entire peripheral end surface was formed. Next, the cover glass (thickness 1 mm) was bonded through the sealing portion (adhesive). Then, through an acrylic adhesive (thickness: 25 μm), the same polarizing plate was also attached to the back side of the glass. The replacement of the liquid crystal display device was produced through the above procedure. At the same time, prepare a substrate paper that has the same size as the polarizer and does not penetrate the visible light. It is placed on the LED light in a state where it is superimposed with the liquid crystal display device replacement, and the end surface of the self-polarizer is visually observed. Discoloration, light leakage, and white haze began to occur nearby. Next, after placing the replacement liquid crystal display device in an environment of 85°C and 85% RH for 120 hours, the substrate paper and LED light were set again, and the discoloration, light leakage, and the like that began to occur near the end face of the polarizer were visually observed. White fog.

[Example 1] An amorphous polyethylene terephthalate (IPA copolymerized PET) film having a thickness of 100 μm and a Tg of 75° C. and having 7 mol% isophthalic acid units was prepared as a resin substrate. Corona treatment (58W/m2/min) was applied to the film surface. Ready to contain acetylacetoyl modified PVA at a ratio of 1:9 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: GOHSEFIMER Z200, average polymerization degree: 1200, saponification degree: 98.5 mol% or more, acetylacetoyl) Chemical degree: 5%) and PVA (average degree of polymerization: 4200, saponification degree: 99.2 mole %) of PVA-based resin, and 13 parts by weight of potassium iodide is added to 100 parts by weight of the PVA-based resin to prepare A PVA-based resin aqueous solution (PVA-based resin concentration: 5.5% by weight). The corona-treated surface of the resin substrate was coated with the aqueous solution so that the film thickness after drying became 13 μm, and dried by hot air under a gas environment of 60° C. for 10 minutes to form a PVA with a thickness of 9 μm on the resin substrate Department of resin layer. The layered body is made through the above procedure. The obtained laminate was extended 2.4 times in air at 140°C (air-assisted extension). Next, the laminate was immersed in a boric acid aqueous solution at a liquid temperature of 30°C for 30 seconds to prevent the PVA-based resin layer from dissolving. The aqueous solution of boric acid in this step is such that the boric acid content is 3 parts by weight relative to 100 parts by weight of water. Next, so that the monomer transmittance of the obtained polarizing film is about 42 to 45%, the laminate is immersed in a dyeing solution containing iodine and potassium iodide at a liquid temperature of 30°C for arbitrary time and dyed. The dyeing solution uses water as a solvent, and the concentration of iodine is in the range of 0.1 to 0.4% by weight, the concentration of potassium iodide is in the range of 0.7 to 2.8% by weight, and the concentration ratio of iodine to potassium iodide is 1:7. Next, the laminate was immersed in a boric acid aqueous solution at a liquid temperature of 30°C for 60 seconds, and a cross-linking treatment was performed on the PVA resin layer that had adsorbed iodine. The boric acid aqueous solution in this step is such that the boric acid content is 3 parts by weight with respect to 100 parts by weight of water, and the potassium iodide content is 3 parts by weight with respect to 100 parts by weight of water. In addition, the laminate was extended in the boric acid aqueous solution at an extension temperature of 70° C. in the same direction as the previous air-assisted extension by 2.3 times (final extension magnification 5.50 times). The boric acid aqueous solution in this step is such that the boric acid content is 3.5 parts by weight with respect to 100 parts by weight of water, and the potassium iodide content is 5 parts by weight with respect to 100 parts by weight of water. Next, the laminate was washed with an aqueous solution having a potassium iodide content of 4 parts by weight with respect to 100 parts by weight of water, and dried with warm air at 60°C, to obtain a polarizing film having a thickness of 5 μm on the resin substrate.

A cycloolefin-based film (manufactured by Zeon Corporation, ZF-12, 13 μm) was bonded to the surface of the obtained polarizing film (the surface on the side opposite to the resin substrate) through a curing adhesive. Specifically, the hardening adhesive is applied to the polarizing film and the cycloolefin-based film to a thickness of 1.0 μm, and bonded using a rolling machine. Thereafter, visible light is irradiated from the cycloolefin-based film side to harden the hardening adhesive. Next, the resin substrate is peeled off to obtain a polarizing plate having a structure of a polarizing film/cycloolefin-based film (protective film). The obtained polarizing plate was used to evaluate the above-mentioned amount of discoloration. The results are shown in Table 1. In addition, the discolored state is shown in FIG. 4.

Take out the liquid crystal panel from the IPS type liquid crystal display device (manufactured by Apple Corporation, trade name "iPad (registered trademark) Air"), remove optical members such as polarizing plates from the liquid crystal panel, and take out the liquid crystal cell. The liquid crystal cell is used after washing and cleaning both surfaces (outside of each glass substrate) with alcohol. After forming an acrylic adhesive layer (thickness: 20 μm) on the surface of the polarizing film of the polarizing plate obtained above, cut it to the same size as the removed polarizing plate (about 150 mm×200 mm), and pass through the adhesive The layer is attached to the viewing side surface of the liquid crystal cell. Next, a sheet-like adhesive (moisture permeability: 24 g/m ² /24hr, thickness: 25 μm) was placed on the surface of the polarizing plate opposite to the liquid crystal cell. At this time, the sheet is arranged to extend from all four sides constituting the outer periphery of the polarizing plate. The length of the four extensions is 5mm each. The sheet sags by its own weight, directly adheres to the liquid crystal cell, and covers the outer peripheral end surface of the polarizing plate to be sealed. Through the above procedure, a sealing portion covering the entire surface of the polarizing plate on the side opposite to the liquid crystal cell and the entire peripheral end surface was formed. Next, the cover glass (thickness 1 mm) was bonded through the sealing portion (adhesive). In addition, the adhesive constituting the sealing part is a block copolymer of styrene-ethylene-propylene copolymer-styrene (made by Kuraray Corporation, trade name "SEPTON 2063") with respect to 100 parts by weight of styrene content: 13% by weight ), blended with 10 parts by weight of polybutene (manufactured by JX Nippon Oil & Energy Co., Ltd., "trade name "Nishiishi Polybutene HV-300"", 40 parts by weight of terpene phenol tackifier (manufactured by Yasuhara Chemical Co., Ltd., product Named "YS Polyster TH130"), and aromatic tackifier (made by Eastman Chemical Co., Ltd., trade name "Piccolastic A5"). Through the acrylic adhesive layer (thickness: 25μm), the same polarized light as above The panel is attached to the back side of the liquid crystal cell. The liquid crystal panel is obtained through the above procedure. After the obtained liquid crystal panel is placed in an environment of 85° C. and 85% RH for 120 hours, it is assembled into the original liquid crystal display device to obtain The liquid crystal display device of this embodiment. After the replacement of the liquid crystal display device of (4) above was used to evaluate fading, light leakage and white fogging, it was confirmed that it was placed in an environment of 85°C and 85%RH for 120 hours It is still a good black display without fading, light leakage and white fogging.

[Example 2] An adhesive (a thickness of 100 μm) with a moisture permeability of 6 g/m ² /24hr was used to form a sealed portion, and a liquid crystal display device and a substitute product were produced in the same manner as in Example 1. As in Example 1, the replacement of the liquid crystal display device of (3) above was used to evaluate the amount of discoloration. The results are shown in Table 1. Furthermore, after the evaluation of the above-mentioned (4) liquid crystal display device substitute was performed for the same evaluation of discoloration, light leakage, and white haze as in Example 1, it was confirmed to be placed in an environment of 85°C and 85%RH for 120 hours After that, it is still a good black display without fading, light leakage and white fogging.

[Example 3] A liquid crystal display device and a substitute product were produced in the same manner as in Example 1 except that an adhesive (thickness of 50 μm) with a moisture permeability of 12 g/m ² /24hr was used to form the sealed portion. As in Example 1, the replacement of the liquid crystal display device of (3) above was used to evaluate the amount of discoloration. The results are shown in Table 1. Furthermore, after the evaluation of the above-mentioned (4) liquid crystal display device substitute was performed for the same evaluation of discoloration, light leakage, and white haze as in Example 1, it was confirmed to be placed in an environment of 85°C and 85%RH for 120 hours After that, it is still a good black display without fading, light leakage and white fogging.

[Example 4] A liquid crystal display device and a substitute product were produced in the same manner as in Example 2 except that the cover glass was not provided. As in Example 1, the replacement of the liquid crystal display device of (3) above was used to evaluate the amount of discoloration. The results are shown in Table 1. Furthermore, after the evaluation of the above-mentioned (4) liquid crystal display device substitute was performed for the same evaluation of discoloration, light leakage, and white haze as in Example 1, it was confirmed to be placed in an environment of 85°C and 85%RH for 120 hours After that, it is still a good black display without fading, light leakage and white fogging.

[Example 5] In the same manner as in Example 1, a laminate having a structure of a polarizing film/cycloolefin-based film (protective film) was obtained. A cycloolefin-based film (manufactured by Zeon Corporation, Japan, ZD-12, 23 μm) is bonded to the surface of the polarizing film of the laminate through a hardening adhesive to obtain a protective film (ZD-12)/polarizing film/protective film (ZF-12) structure of polarizing plate. An acrylic adhesive was formed on the surface of the protective film (ZF-12) of the polarizing plate. Except for the same manner as in Example 3, a liquid crystal display device and a substitute product were produced. As in Example 1, the replacement of the liquid crystal display device of (3) above was used to evaluate the amount of discoloration. The results are shown in Table 1. Furthermore, after the evaluation of the above-mentioned (4) liquid crystal display device substitute was performed for the same evaluation of discoloration, light leakage, and white haze as in Example 1, it was confirmed to be placed in an environment of 85°C and 85%RH for 120 hours After that, it is still a good black display without fading, light leakage and white fogging.

[Example 6] A PVA-based resin film (manufactured by Kuraray Corporation, trade name "PE-6000", thickness: 60 μm, average polymerization degree: 2,400, saponification degree 99.9 mol %) was immersed in a 30°C water bath for 1 minute and After extending 1.2 times in the conveying direction, it was immersed in a 30°C aqueous solution with an iodine concentration of 0.04% by weight and a potassium concentration of 0.3% by weight for dyeing, and it was stretched twice based on the completely unstretched film (original length). Then, the stretched film was immersed in an aqueous solution at 30° C. with a boric acid concentration of 3% by weight and a potassium iodide concentration of 3% by weight, and further extended to 3 times based on the original length, and then immersed in a boric acid concentration of 4% by weight and a potassium iodide concentration of 5 In a 60% by weight aqueous solution at 60° C., the original length was further extended to 6 times, and then dried at 70° C. for 2 minutes, thereby obtaining a polarizing film with a thickness of 23 μm. Next, a PVA-based resin aqueous solution (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER (registered trademark) Z-200", resin concentration: 3% by weight) was applied on both sides of the polarizing film, and the cycloolefin-based films ( Made by Zeon Corporation of Japan, Zeonor ZF14, thickness: 13 μm) and triacetyl cellulose film (manufactured by Konica Minolta Corporation, KC4UY), and then heated in an oven maintained at 60° C. for 5 minutes to obtain a polarizing plate. The subsequent procedure was to produce a liquid crystal display device and substitutes in the same manner as in Example 2. As in Example 1, the replacement of the liquid crystal display device of (3) above was used to evaluate the amount of discoloration. The results are shown in Table 1. In addition, after the evaluation of the above-mentioned (4) liquid crystal display device substitute was performed for the same evaluation of discoloration, light leakage, and white haze as in Example 1, it was confirmed to be placed in an environment of 85°C and 85%RH for 120 hours After that, there is still a good black display without fading, light leakage and white fogging.

[Example 7] A smartphone (Galaxy-S5) manufactured by Samsung Wireless Co., Ltd. using a polarizing plate for anti-reflection purposes was disassembled to take out an organic EL display device. The polarizing plate attached to the organic EL display device was peeled and removed, and the surface after removing the polarizing plate was washed. The polarizing plate used in Example 3 (whose sealing portion was formed, and had been placed in an environment of 85° C. and 85% RH for 120 hours) was stuck on the removed surface to obtain an organic EL display device. After the obtained organic EL display device was rendered black, it was confirmed that it was a good black display without fading, light leakage, or white fogging.

[Comparative Example 1] 70 parts of 2-ethylhexyl acrylate (2EHA), 15 parts of N-vinylpyrrolidone (NVP), and 15 parts of 2-hydroxyethyl acrylate (2HEA), 0.3 One part of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator was added together with 150 parts of ethyl acetate, and after stirring for 1 hour in a nitrogen atmosphere at 23°C, it was kept at 58°C The reaction was carried out for 4 hours and then at 70°C for 2 hours to prepare an acrylic polymer solution. After preparing the acrylic polymer solution, 0.3 parts by weight of 3-glycidoxypropyltrimethoxysilane (brand name: KBM403, Shin-Etsu Chemical Co., Ltd.), and 0.4 parts of trimethylolpropane adduct of stubble diisocyanate as a crosslinking agent (trade name: TAKENATE D110N, Mitsui Chemicals Co., Ltd.) Mix evenly to prepare an acrylic adhesive. The moisture permeability of the obtained adhesive (thickness 100 μm) is greater than 1000 g/m ² /24hr. Except that the adhesive was used to form the sealed portion, a liquid crystal display device and a substitute product were produced in the same manner as in Example 1. As in Example 1, the replacement of the liquid crystal display device of (3) above was used to evaluate the amount of discoloration. The results are shown in Table 1. Furthermore, after the evaluation of the discoloration, light leakage, and white haze as in Example 1 was carried out using the liquid crystal display device substitute of the above (4), it was confirmed that there was light leakage due to the discoloration of the polarizing plate.

[Comparative Example 2] A sheet-shaped adhesive with the same size as the polarizing plate is used to form a sealing portion only on the surface of the polarizing plate on the side opposite to the liquid crystal cell (that is, it does not cover the peripheral end surface of the polarizing plate). In the same manner as in Example 3, a liquid crystal display device and a substitute product were produced. As in Example 1, the replacement of the liquid crystal display device of (3) above was used to evaluate the amount of discoloration. The results are shown in Table 1. In addition, after the evaluation of discoloration, light leakage, and white haze in the same manner as in Example 1 was performed on the replacement of the liquid crystal display device of (4) above, it was confirmed that there was light leakage due to the discoloration of the polarizing plate.

[Comparative Example 3] A sheet adhesive with a size smaller than that of the polarizing plate is used to form a sealing portion only on a part of the surface of the polarizing plate on the side opposite to the liquid crystal cell (that is, the peripheral end surface of the polarizing plate is not covered), in addition to In the same manner as in Example 3, a liquid crystal display device and a substitute product were produced. As in Example 1, the replacement of the liquid crystal display device of (3) above was used to evaluate the amount of discoloration. The results are shown in Table 1. In addition, after the evaluation of discoloration, light leakage, and white haze in the same manner as in Example 1 was performed on the replacement of the liquid crystal display device of (4) above, it was confirmed that there was light leakage due to the discoloration of the polarizing plate.

[Comparative Example 4] A liquid crystal display device and a substitute product were produced in the same manner as in Example 1, except that the sealing portion was not formed and the cover glass was not arranged. As in Example 1, the replacement of the liquid crystal display device of (3) above was used to evaluate the amount of discoloration. The results are shown in Table 1. In addition, after the evaluation of discoloration, light leakage, and white haze in the same manner as in Example 1 was performed on the replacement of the liquid crystal display device of (4) above, it was confirmed that there was light leakage due to the discoloration of the polarizing plate.

[Table 1]

As is apparent from Table 1, by forming a sealing portion having a predetermined moisture permeability on the outer peripheral end surface of the polarizing plate, an image display device that can maintain excellent optical characteristics under a humidified environment can be obtained.

INDUSTRIAL APPLICABILITY The image display device of the present invention can be applied to televisions, mobile phones, digital cameras, digital cameras, handheld game consoles, car navigation, photocopiers, printers, fax machines, clocks, microwave ovens, and the like.

10‧‧‧Liquid crystal unit 20‧‧‧Polarizing plate 21‧‧‧Polarizing film 22‧‧‧Protective film 30‧‧‧Sealing part 40‧‧‧Cover glass 50‧‧‧Adhesive layer 100‧‧‧Liquid crystal display device

1 is a schematic partial cross-sectional view of an image display device according to an embodiment of the present invention. FIG. 2 is a schematic diagram for explaining the calculation of the amount of discoloration. 3 is a schematic diagram for explaining an example of a method of manufacturing an image display device of the present invention. 4 is an image showing the amount of discoloration corresponding to the replacement liquid crystal display device of Example 1 after the humidification test. FIG. 5 is an image showing the amount of discoloration corresponding to the replacement of the liquid crystal display device of Comparative Example 1 after the humidification test.

10‧‧‧LCD unit

20‧‧‧ Polarizer

21‧‧‧ Polarizing film

22‧‧‧Protection film

30‧‧‧Seal

40‧‧‧ Cover glass

50‧‧‧adhesive layer

100‧‧‧LCD display device

Claims (9)

An image display device comprising: a display unit; a polarizing plate arranged on at least one side of the display unit; and a sealing portion for covering the peripheral end surface of the polarizing plate; and the polarizing plate includes a polyvinyl alcohol system containing iodine In the polarizing film composed of a resin film, the sealing portion is a sheet-shaped adhesive, and the moisture permeability of the sealing portion is 300 g/m ² /24hr or less. The image display device according to claim 1, wherein the sealing portion is used to cover the entire surface of the polarizing plate on the side opposite to the display unit and the entire surface of the peripheral end surface. The image display device according to claim 1, wherein the thickness of the sealing portion is 10 μm to 100 μm. The image display device according to claim 1, wherein the sealing portion is made of an adhesive composition. The image display device according to claim 4, wherein the sealing portion is made of a rubber-based adhesive. The image display device according to claim 1 further includes a cover glass, which is disposed on the opposite side of the polarizing plate from the display unit. As for the image display device of claim 1, the discoloration after 120 hours at 85°C and 85%RH is 100 μm or less. A method for manufacturing an image display device includes the following steps: disposing a polarizing plate on one side of a display unit; and disposing a sheet composed of an adhesive composition so as to cover the peripheral end surface of the polarizing plate, thereby forming a sealing portion ; Wherein the size of the sheet is larger than that of the polarizing plate, and the method is to arrange the sheet in such a manner as to cover the entire surface of the polarizing plate on the side opposite to the display unit and the entire surface of the surrounding end surface to form a sealing portion; And, the polarizing plate includes a polarizing film composed of a polyvinyl alcohol-based resin film containing iodine, and the moisture permeability of the sealing portion is 300 g/m ² /24hr or less. The method for manufacturing an image display device according to claim 8 further includes the following steps: disposing a cover glass on the opposite side of the polarizing plate from the display unit.

Images