JPWO2018235462A1 - Method of manufacturing image display device and image display device obtained by the method - Google Patents

Abstract

It is possible to provide a simple method for producing a polarizing plate with a substrate which can maintain excellent optical characteristics even in a humid environment and prevent color loss. The method for producing a polarizing plate with a substrate according to the present invention includes preparing a polarizing plate and a substrate having a size larger than the polarizing plate; laminating the substrate and the polarizing plate such that the substrate extends from the outer periphery of the polarizing plate. Forming a sealing portion covering the peripheral end surface of the polarizing plate; and cutting the substrate and the sealing portion to a predetermined size while leaving a portion extending from the peripheral end of the polarizing plate by a predetermined length. That;

Description

  The present invention relates to a method for manufacturing an image display device and an image display device obtained by the method.

  Image display devices (for example, liquid crystal display devices, organic EL display devices, and quantum dot display devices) often have a polarizing plate disposed on at least one side of a display cell due to the image forming method. I have. However, the polarizing plate has a durability problem that the optical characteristics of the polarizing film, which substantially govern the optical characteristics of the polarizing plate, are reduced in a humid environment. More specifically, the polarizing film loses its polarization performance in an end portion under a humid environment, and as a result, a phenomenon called color loss may occur in the image display device.

JP 2000-338329 A

  The present invention has been made to solve the above-described problems, and a main object of the present invention is to provide an image display device capable of maintaining excellent optical characteristics even in a humid environment, preventing color omission, and a simple manufacturing method thereof. Is to provide.

In the method for manufacturing an image display device according to the present invention, a polarizing plate and a substrate having a size larger than the polarizing plate are provided; the substrate extends from the outer periphery of the polarizing plate; Laminating the substrate and the sealing portion; and forming a sealing portion covering the peripheral end surface of the polarizing plate; and leaving the extending portion of a predetermined length from the peripheral end of the polarizing plate to the substrate and the sealing portion. Cutting to a predetermined size.
In one embodiment, the substrate is a glass plate. In another embodiment, the substrate is a resin film.
In one embodiment, the manufacturing method includes laminating the substrate and the polarizing plate such that the substrate extends from all four sides constituting the outer periphery of the polarizing plate.
In one embodiment, the substrate is a display cell substrate of an image display device selected from a liquid crystal display device, an organic EL display device, and a quantum dot display device.
In one embodiment, the cutting is performed by irradiating a laser beam.
In one embodiment, the length of the extending portion of the sealing portion after the cutting is 10 μm to 500 μm.
In one embodiment, the moisture permeability of the sealing portion after the cutting is less than 300g ^/ m 2 ^/ 24hr.
According to another aspect of the present invention, an image display device is provided. This image display device includes a polarizing plate, a substrate having a portion extending from the peripheral edge of the polarizing plate by a predetermined length, and a sealing portion formed on the extending portion and covering a peripheral end surface of the polarizing plate. Have.

  According to the present invention, in a method for manufacturing an image display device, a sealing portion is formed on a portion of a substrate extending from a polarizing plate to seal a peripheral end surface of the polarizing plate, and a sealing portion and a corresponding substrate are extended. By cutting the protruding portion leaving a predetermined length from the peripheral edge of the polarizing plate, excellent optical characteristics can be maintained even in a humid environment, and an image display device in which color omission is prevented is easily manufactured. be able to.

FIG. 4 is a schematic diagram for explaining a method for manufacturing an image display device according to one embodiment of the present invention. FIG. 4 is a schematic diagram for explaining calculation of a color missing amount. 4 is an image showing the amount of color missing after a humidification test of a polarizing plate with a substrate as a substitute for the image display device of Example 1. 9 is an image showing the amount of color missing after a humidification test of a polarizing plate with a substrate as an alternative to the image display device of Comparative Example 1.

  Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

A. Method for Manufacturing Image Display Device The method for manufacturing an image display device of the present invention includes preparing a polarizing plate and a substrate having a size larger than the polarizing plate; so that the substrate extends from the outer periphery of the polarizing plate. Laminating the substrate and the polarizing plate; forming a sealing portion for covering a peripheral end surface of the polarizing plate; and leaving a portion extending from the peripheral end of the polarizing plate by a predetermined length. And cutting the sealing portion to a predetermined size.

  The present invention is applicable to any laminated structure of a substrate and a polarizing plate in an image display device. The substrate may typically be a display cell substrate of an image display device. Typical examples of the image display device include a liquid crystal display device, an organic EL display device, and a quantum dot display device. Examples of the display cell substrate include a liquid crystal cell substrate, an organic EL cell substrate, a quantum dot display cell substrate, and a substrate for sealing a color filter from both sides in a liquid crystal display device. In one embodiment, the manufacturing method of the present invention laminates a substrate and a polarizing plate, forms a sealing portion on the laminate to produce a polarizing plate with a substrate, and displays the polarizing plate with a substrate on a display cell. By using it as a substrate, an image display device can be obtained. In the manufacturing method of the present invention, in another embodiment, an image display device can be obtained by manufacturing a display cell, stacking a polarizing plate on a substrate of the display cell, and then forming a sealing portion. . Hereinafter, an embodiment in which a polarizing plate with a substrate is used as a display cell substrate will be described as a representative example.

A-1. Preparation of Polarizing Plate and Substrate First, as shown in FIG. 1A, a polarizing plate 10 and a substrate 20 are prepared. Hereinafter, the polarizing plate and the substrate will be specifically described.

A-1-1. Polarizing plate The polarizing plate has a polarizing film and a protective film disposed on at least one side of the polarizing film. In the embodiment of the present invention, the polarizing film is formed of a polyvinyl alcohol-based resin (hereinafter, referred to as “PVA-based resin”) film containing iodine. When the polarizing film contains iodine, the effect of providing the sealing portion becomes remarkable. The thickness of the polarizing film is typically 8 μm or less. When the polarizing film contains iodine, and the thickness is such a very thin, the iodine density in the polarizing film is increased, and the stability of iodine due to humidification is easily reduced, so a sealing portion is provided. The effect becomes more remarkable. The protective film may be disposed on one side of the polarizing film, or may be disposed on both sides. When the protective film is disposed on one side of the polarizing film, it may be disposed on the display cell side or may be disposed on the opposite side of the display cell. Practically, an adhesive layer is provided as the outermost layer on the display cell side of the polarizing plate, and the polarizing plate is bonded to the display cell via the adhesive layer. In this specification, the term “protective film” simply means a film that protects such a polarizing film (a component of a polarizing plate), and the above-mentioned surface protective film (a film that temporarily protects a polarizing plate during operation). ).

A-1-1-1. Polarizing Film The polarizing film is composed of a PVA-based resin film containing iodine as described above. The polarizing film may be formed from a single-layer resin film, or may be formed from a laminate of two or more layers.

  Specific examples of the polarizing film formed from a single-layer resin film include hydrophilic polymer films such as a polyvinyl alcohol (PVA) -based film, a partially formalized PVA-based film, and an ethylene / vinyl acetate copolymer-based partially saponified film. And polyene-based oriented films such as those subjected to a dyeing treatment and a stretching treatment with a dichroic substance such as iodine or a dichroic dye, and a dehydration treatment of PVA and a dehydrochlorination treatment of polyvinyl chloride. Preferably, a polarizing film obtained by dyeing a PVA-based film with iodine and uniaxially stretching is used because of its excellent optical properties. The dyeing with iodine is performed, for example, by immersing a PVA-based film in an aqueous iodine solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment or may be performed while dyeing. Moreover, you may dye after extending | stretching. If necessary, the PVA-based film is subjected to a swelling treatment, a crosslinking treatment, a washing treatment, a drying treatment and the like. For example, by immersing the PVA-based film in water and washing it with water before dyeing, not only can the dirt and the antiblocking agent on the surface of the PVA-based film be washed, but also the swelling of the PVA-based film causes uneven dyeing. Can be prevented.

  Specific examples of the polarizing film obtained by using the laminate include a laminate of a resin base and a PVA-based resin layer (PVA-based resin film) laminated on the resin base, or a resin base and the resin A polarizing film obtained by using a laminate with a PVA-based resin layer applied and formed on a substrate is exemplified. For example, a polarizing film obtained by using a laminate of a resin base material and a PVA-based resin layer applied to the resin base material is applied by applying a PVA-based resin solution to the resin base material and drying the resin base material. Forming a PVA-based resin layer thereon to obtain a laminate of a resin substrate and a PVA-based resin layer; stretching and dyeing the laminate to form a PVA-based resin layer into a polarizing film; obtain. In the present embodiment, the stretching typically includes immersing the laminate in a boric acid aqueous solution and stretching. Further, the stretching may optionally further include stretching the laminate in air at a high temperature (for example, 95 ° C. or higher) before stretching in a boric acid aqueous solution. The obtained resin substrate / polarizing film laminate may be used as it is (that is, the resin substrate may be used as a protective film for the polarizing film), or the resin substrate is separated from the resin substrate / polarizer laminate. Then, any appropriate protective film depending on the purpose may be laminated on the release surface and used. Details of such a method for manufacturing a polarizing film are described in, for example, JP-A-2012-73580. This publication is incorporated herein by reference in its entirety.

  Any appropriate resin can be adopted as the PVA-based resin forming the PVA-based resin film. For example, polyvinyl alcohol and an ethylene-vinyl alcohol copolymer are mentioned. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcohol copolymer is obtained by saponifying the ethylene-vinyl acetate copolymer. The degree of saponification of the PVA-based resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.9 mol%, more preferably 99.0 mol% to 99.5 mol%. . The saponification degree can be determined according to JIS K 6726-1994. By using a PVA-based resin having such a saponification degree, a polarizing film having excellent durability can be obtained. If the degree of saponification is too high, gelation may occur.

  The average degree of polymerization of the PVA-based resin can be appropriately selected depending on the purpose. The average degree of polymerization is usually from 1,000 to 10,000, preferably from 1,200 to 5,000, more preferably from 1,500 to 4,500. The average degree of polymerization can be determined according to JIS K 6726-1994.

  As described above, the polarizing film contains iodine. The polarizing film is substantially a PVA-based resin film in which iodine is adsorbed and oriented. The iodine concentration in the PVA-based resin film is, for example, 5.0% by weight to 12.0% by weight. 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 polarizing film is typically 8 μm or less, preferably 7 μm or less, more preferably 6 μm or less. On the other hand, the thickness of the PVA-based resin film is preferably at least 1.0 μm, more preferably at least 2.0 μm.

  The polarizing film preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance of the polarizing film is preferably 40.0% to 46.0%, more preferably 41.0% to 45.0%. The degree of polarization of the polarizing film is preferably at least 99.9%, more preferably at least 99.95%, even more preferably at least 99.98%. When the polarizing plate is applied to a reflective liquid crystal display device or an organic EL display device, the degree of polarization of the polarizing film is preferably 90% or more, more preferably 93% or more, and even more preferably 95%. That is all. As described later, by providing a sealing portion covering the peripheral end surface of the image display panel including the polarizing film, such excellent optical properties (excellent balance between the single transmittance and the degree of polarization) and excellent durability are provided. (That such excellent optical properties can be maintained even in a humidified environment).

A-1-1-2. Protective film The protective film is composed of any appropriate film that can be used as a protective film for the polarizing film. Specific examples of the material that is the main component of the film include a cellulose resin such as triacetyl cellulose (TAC), a polyester, a polyvinyl alcohol, a polycarbonate, a polyamide, a polyimide, a polyethersulfone, and a polysulfone. And transparent resins such as polystyrene-based, polynorbornene-based, polyolefin-based, (meth) acryl-based, and acetate-based resins. Further, a thermosetting resin such as a (meth) acrylic, urethane-based, (meth) acrylic urethane-based, epoxy-based, or silicone-based resin or an ultraviolet-curable resin may also be used. In addition to this, for example, a vitreous polymer such as a siloxane-based polymer may also be used. Further, a polymer film described in JP-A-2001-343529 (WO 01/37007) can also be used. As a material of the film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in a side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in a side chain And, for example, a resin composition having an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer. The polymer film may be, for example, an extruded product of the resin composition.

  In the embodiment of the present invention, as described above, the resin base used in the production of the polarizing plate may be used as it is as the protective film.

  When the protective film is disposed on the viewing side of the polarizing film in the polarizing plate disposed on the viewing side, the protective film may be provided with a hard coat treatment, an anti-reflection treatment, an anti-sticking treatment, an anti-glare treatment, etc., as necessary. May be applied.

  Any appropriate thickness can be adopted as the thickness of the protective film as long as the effects of the present invention can be obtained. The thickness of the protective film is, for example, 10 μm to 40 μm, and preferably 10 μm to 30 μm. When the surface treatment has been performed, the thickness of the protective film is a thickness including the thickness of the surface treatment layer.

  When a protective film (inner protective film) is disposed on the display cell side of the polarizing film, in one embodiment, the inner protective film is preferably optically isotropic. In the present 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. Say. Re (550) of the inner protective film is preferably from 0 nm to 8 nm, more preferably from 0 nm to 6 nm, and still more preferably from 0 nm to 3 nm. Rth (550) of the inner protective film is preferably from -8 nm to +8 nm, more preferably from -6 nm to +6 nm, and still more preferably from -3 nm to +3 nm. “Re (550)” is an in-plane retardation measured with light having a wavelength of 550 nm at 23 ° C. Re (550) is determined by the formula: Re = (nx−ny) × d, where d (nm) is the thickness of the layer (film). “Rth (550)” is a retardation in the thickness direction measured with light having a wavelength of 550 nm at 23 ° C. Rth (λ) is determined by the formula: Rth = (nx−nz) × d, where d (nm) is the thickness of the layer (film).

  In another embodiment, the inner protective film may have Re (550) such that it can function as a so-called λ / 4 plate. Such an embodiment can be applied, for example, when the polarizing plate functions as a circular polarizing plate and is used as an antireflection film of a reflective liquid crystal display device or an organic EL display device. In this case, Re (550) is preferably between 120 nm and 160 nm, more preferably about 140 nm. In this case, the inner protective film may be arranged such that its slow axis forms an angle of preferably 40 ° to 50 °, more preferably about 45 ° with the absorption axis of the polarizing film.

A-1-2. Substrate Any appropriate configuration can be adopted as the substrate. For example, the substrate may be a glass plate or a resin film. The substrate has a size larger than the polarizing plate. The substrate preferably has such a size as to extend a predetermined length from the outer periphery of the polarizing plate when laminated with the polarizing plate, and more preferably has a predetermined length from all four sides constituting the outer periphery of the polarizing plate. It has a size to extend.

Any appropriate glass plate can be adopted as the glass plate. According to the classification according to the composition, the glass constituting the glass plate includes, for example, soda-lime glass, borate glass, aluminosilicate glass, and quartz glass. Further, according to the classification based on the alkali component, non-alkali glass and low alkali glass are mentioned. The content of alkali metal components (for example, Na ₂ O, K ₂ O, and Li ₂ O) in the glass is preferably 15% by weight or less, more preferably 10% by weight or less.

The light transmittance of the glass plate at a wavelength of 550 nm is preferably 85% or more. The refractive index at a wavelength of 550 nm of the glass plate is preferably 1.4 to 1.65. The density of the glass plate is preferably ^{2.3g / cm 3 ~3.0g / cm 3} , even more preferably ^{2.3g / cm 3 ~2.7g / cm 3} .

  The thickness of the glass plate is preferably 0.1 mm to 1.0 mm, and more preferably 0.2 mm to 0.6 mm.

  As the glass plate, a commercially available glass plate may be used as it is, or a commercially available glass plate may be polished to a desired thickness and used. Examples of commercially available glass plates include, for example, “7059”, “1737” or “EAGLE2000” manufactured by Corning, “AN100” manufactured by Asahi Glass, “NA-35” manufactured by NH Techno Glass, and “OA-” manufactured by NEC Glass 10 "and" D263 "or" AF45 "manufactured by Schott.

  Any appropriate resin film can be adopted as the resin film. The resin film is typically a transparent resin film. Examples of the material constituting the resin film include polyimide and polyamide imide. These may be used alone or in combination.

  The thickness of the resin film is preferably from 10 μm to 200 μm, and more preferably from 20 μm to 100 μm.

A-2. Lamination of Polarizing Plate and Substrate Next, as shown in FIG. 1A, the polarizing plate 10 and the substrate 20 are laminated. Typically, the polarizing plate 10 and the substrate 20 can be laminated via any appropriate pressure-sensitive adhesive layer (not shown). The lamination is performed so that the substrate extends from the outer periphery of the polarizing plate as shown in FIG. 1A, and preferably the substrate extends from all four sides constituting the outer periphery of the polarizing plate. Is

  If necessary, a surface protection film (not shown) may be temporarily attached to the surface of the polarizing plate 10 opposite to the substrate 20. Thereby, the polarizing plate can be appropriately protected in the formation of the sealing portion described later and the cutting of the sealing portion and the substrate. The surface protective film is peeled and removed at the time of final use of the polarizing plate with substrate (substantially, an image display device). The peeling and removal of the surface protection film can be performed at any appropriate timing after the formation of the sealing portion and the cutting of the sealing portion and the substrate.

A-3. Formation of Sealing Part Next, as shown in FIG. 1B, a sealing part 30 that covers the peripheral end surface of the polarizing plate 10 is formed. By covering the peripheral end surface of the polarizing plate with the sealing portion, the optical characteristics of the polarizing plate (polarizing film) can be maintained even in a humid environment, and as a result, the durability of the image display device can be improved. Therefore, the sealing portion preferably has a barrier function. In the present specification, “having a barrier function” means that the amount of oxygen and / or water vapor that penetrates into the polarizing film is controlled to substantially block the polarizing film from these.

  The sealing portion is typically formed by disposing the pressure-sensitive adhesive composition so as to cover the peripheral end surface of the polarizing plate. In one embodiment, the sealing portion can be formed by arranging (for example, coating, arranging a sheet-shaped adhesive) the extended portion of the substrate on the adhesive composition. The sealing portion covers the peripheral end surface of the polarizing plate, and the peripheral end surface need only be sealed, and need not be in close contact with the peripheral end surface. Further, the sealing portion only needs to cover the peripheral end surface of the polarizing plate, and thus may cover a part other than the peripheral end surface together with the peripheral end surface. For example, the sealing portion may cover the surface (the upper surface in the drawing) on the side of the polarizing plate away from the substrate together with the peripheral end surface. In this case, the surface may be entirely covered, or only a predetermined portion may be covered.

  Examples of the pressure-sensitive adhesive composition include a rubber-based pressure-sensitive adhesive composition containing a rubber-based polymer as a base polymer.

  Examples of the rubber-based polymer include a conjugated diene-based polymer obtained by polymerizing one kind of conjugated diene compound, a conjugated diene-based copolymer obtained by polymerizing two or more kinds of conjugated diene compounds, and a conjugated diene. Conjugated diene-based copolymers obtained by copolymerizing a compound with an aromatic vinyl compound, and hydrogenated products thereof.

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

  The diene copolymer may be a random copolymer or a block copolymer. Further, a compound other than the conjugated diene compound and the aromatic vinyl compound may be copolymerized to obtain a diene-based copolymer.

  The conjugated diene-based copolymer obtained by copolymerizing a conjugated diene compound and an aromatic vinyl compound has a molar ratio of conjugated diene compound to aromatic vinyl compound of conjugated diene compound / aromatic vinyl compound = 10/90. ９０90/10 (mol%) is preferable.

  Specific examples of such a conjugated diene (co) polymer include butadiene rubber (BR), isoprene rubber (IR), styrene-butadiene copolymer (SBR), butadiene-isoprene-styrene random copolymer, and isoprene. -Styrene random copolymer, styrene-isoprene block copolymer (SIS), butadiene-styrene copolymer, styrene-ethylene-butadiene block copolymer (SEBS), acrylonitrile-butadiene rubber (NBR). These may be used alone or in combination. Among these, isoprene-styrene copolymer is preferable. Further, these hydrogenated products can also be suitably used.

  As the rubber-based polymer, besides the conjugated diene-based (co) polymer, isobutylene (IB), styrene-isobutylene-styrene block copolymer (SIBS), styrene-ethylene propylene copolymer-styrene block copolymer, etc. Can also be used. The rubber-based polymers may be used alone or in combination.

  The rubber-based polymer that can be used in the present invention is such that the conjugated diene-based (co) polymer is preferably at least 50% by weight, more preferably at least 70% by weight, and still more preferably at least 80% by weight in the entire rubber-based polymer. And more preferably 90% by weight or more. The upper limit of the content of the conjugated diene (co) polymer is not particularly limited, and may be 100% by weight (that is, a rubber-based polymer composed of only the conjugated diene (co) polymer).

  As described above, the pressure-sensitive adhesive composition contains a rubber-based polymer as a base polymer. The content of the rubber-based polymer in the pressure-sensitive adhesive composition is preferably 40% by weight or more, more preferably 50% by weight or more, and further 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.

  The pressure-sensitive adhesive composition may further include any appropriate additive in addition to the rubber-based polymer. Specific examples of the additive include a crosslinking agent (for example, polyisocyanate, epoxy compound, alkyl etherified melamine compound, etc.), a tackifier (for example, rosin derivative resin, polyterpene resin, petroleum resin, oil-soluble phenol resin, vinyl toluene Resins, plasticizers, fillers (eg, layered silicates, clay materials, etc.), and antioxidants. The type, combination, addition amount, and the like of the additives added to the pressure-sensitive adhesive composition can be appropriately set according to the purpose. The content (total amount) of the additives in the pressure-sensitive adhesive composition is preferably 60% by weight or less, more preferably 50% by weight or less, and further preferably 40% by weight or less.

  The thickness of the sealing portion 30 thus formed is preferably 30 μm to 1000 μm, and more preferably 50 μm to 500 μm. In the present specification, the “thickness of the sealing portion” is a thickness in a direction extending outward from the peripheral end surface of the polarizing plate unless otherwise specified (that is, the thickness of the sealing portion is equal to the length of the extended portion of the substrate). Corresponding to).

A-4. Next, as shown in FIG. 1C, the sealing portion 30 and the substrate 20 are cut while leaving a portion extending from the peripheral edge of the polarizing plate by a predetermined length. As a result, a sealing portion 40 having a predetermined thickness is formed as shown in FIG. The thickness of the sealing portion 40 after cutting is preferably from 10 μm to 500 μm, and more preferably from 20 μm to 300 μm.

  The cutting may be performed mechanically or by irradiating a laser beam.

  Examples of mechanical cutting include milling and end milling.

  The laser light preferably includes light having a wavelength of at least 1500 nm or less. The laser light more preferably includes light having a wavelength of 100 pm to 1000 nm, further preferably includes light having a wavelength of 400 nm to 900 nm, and particularly preferably includes light having a wavelength of 420 nm to 680 nm. In one embodiment, the laser light has a peak wavelength in the above range. According to the laser light having such a wavelength, it is possible to satisfactorily cut over the upper and lower thickness directions of the sealing portion.

  Examples of the laser include a solid laser such as a YAG laser, a YLF laser, a YVO4 laser, a titanium sapphire laser, a gas laser including an argon ion laser, a krypton ion laser, a fiber laser, a semiconductor laser, and a dye laser. Preferably, a solid-state laser is used.

  As the laser, a short-pulse laser (a laser that emits light having a pulse width of 1 nanosecond or less, for example, a picosecond laser or a femtosecond laser) is preferably used. For the purpose of suppressing thermal damage to the sealing portion, a pulse width of 500 picoseconds or less (for example, 10 picoseconds to 50 picoseconds) is particularly preferable. By suppressing the thermal damage, a beautiful, uniform and smooth cut surface can be obtained.

The irradiation condition of the laser beam can be set to any appropriate condition. For example, when using a solid laser (YVO4 laser), the pulse energy is preferably 10 μJ to 150 μJ, more preferably 25 μJ to 71 μJ. The scanning speed is preferably from 10 mm / sec to 10000 mm / sec, more preferably from 100 mm / sec to 1000 mm / sec. The repetition frequency is, for example, 100 Hz to 12480 Hz. The scan pitch is preferably 10 μm to 50 μm. The beam shape at the irradiation position of the laser beam can be appropriately set according to the purpose. The beam shape may be, for example, circular or linear. Any appropriate means can be adopted as a means for forming the beam shape into a predetermined shape. For example, laser irradiation may be performed through a mask having a predetermined opening, or beam shaping may be performed using a diffractive optical element or the like. For example, when the beam shape is circular, the focal diameter (spot diameter) is preferably 50 μm to 60 μm. Further, the input energy of the pulse laser is preferably 20,000 μJ / mm ^{2 to} 100,000 μJ / mm ² , more preferably 25,000 μJ / mm ^{2 to} 75,000 μJ / mm ² . The input energy E (μJ / mm ² ) is obtained from the following equation.
E = (e × M) / (V × p)
e: pulse energy (J)
M: Repetition frequency (Hz)
V: Scan speed (mm / sec)
p: scan pitch (mm)

  The irradiation mode (scanning mode) of the laser beam can be set appropriately according to the purpose. The laser beam may be scanned, for example, linearly, may be scanned in an S shape, may be scanned in a spiral, or may be combined.

The sealing portion 40 formed as described above has a barrier property, and typically has a barrier property against moisture and a gas (for example, oxygen). 40 ° C. of the sealing portion 40, the water vapor transmission rate at 90% RH conditions (moisture permeability) is preferably not more than 300g ^/ m 2 ^/ 24hr, more preferably at most 100g ^/ m 2 ^/ 24hr, further preferably not more than ^50g / m 2 / 24hr, most preferably not more than ^25g / m 2 / 24hr. The lower limit of the moisture permeability, for example, 0.01g ^/ m 2 ^/ 24hr, and preferably below the detection limit. When the moisture permeability of the sealing portion 40 is in such a range, the image display panel can be well protected from moisture and oxygen in the air. The moisture permeability can be measured according to JIS Z0208.

  As described above, as shown in FIG. 1D, a polarizing plate with a substrate 100 having a predetermined size can be manufactured.

A-5. Production of Image Display Device In the present embodiment, an image display device can be obtained by using the polarizing plate with substrate obtained as described above as a display cell substrate. When manufacturing a liquid crystal display device, for example, the following procedure can be adopted: (1) preparing a pair of polarizing plates with a substrate; (2) forming a pair of polarizing plates with a substrate. A switching element (for example, a TFT) is provided, and a color filter is provided on the substrate surface of the other polarizing plate with a substrate; (3) An alignment film is formed on each substrate surface, and the alignment film is subjected to an alignment process; ) The substrates are opposed to each other (the polarizing plate is disposed outside), and the polarizing plate with the substrate is bonded via a spacer; (5) The liquid crystal is sealed between the substrates. Thus, an image display device can be manufactured.

A-6. Other Embodiments Embodiments in which a polarizing plate with a substrate is used as a display cell substrate have been described above. However, as described above, the manufacturing method of the present invention produces a display cell, and attaches a polarizing plate to the substrate of the display cell. By laminating and then forming a sealing portion, an image display device can be obtained. In the present embodiment, the following procedure can be adopted as an example:
(A-1) preparing a pair of substrates; (a-2) providing a switching element (for example, TFT) on one substrate surface and providing a color filter on the other substrate surface; (a-3) providing each substrate (A-4) bonding a substrate through a spacer; (a-5) sealing a liquid crystal between the substrates to form a display cell;
(B) The display cells extend from the outer periphery of the polarizing plate (preferably, the display cells extend from all four sides constituting the outer periphery of the polarizing plate), and the respective substrates of the display cell A polarizing plate laminated on the outside;
(C) forming a sealing portion covering a peripheral end surface of the polarizing plate;
(D) The sealing portion and the peripheral edge of the display cell are cut off while leaving a portion extending a predetermined length from the peripheral edge of the polarizing plate.
Thus, an image display device can be manufactured. The details of the steps (b) to (d) are as described in the above sections A-2 to A-4. In addition, a margin for cutting is secured in the peripheral portion of the display cell so that there is no adverse effect of cutting.

  It is obvious to those skilled in the art that the present invention is applicable to any laminated structure of a substrate and a polarizing plate in an image display device other than the above-described embodiment. After reading this specification, those skilled in the art will understand that the lamination of the substrate and the polarizing plate, the formation of the sealing portion, and the cutting of the sealing portion and the substrate can be performed by an arbitrary laminated structure of the substrate and the polarizing plate in the image display device. Can be applied to

B. Image Display Device The image display device of the present invention is obtained by the manufacturing method described in the above section A. Therefore, the image display device typically includes a structure as shown in FIG. Specifically, the image display device includes a polarizing plate, a substrate having a portion extending from the peripheral edge of the polarizing plate by a predetermined length, and a sealing member formed on the extending portion and covering a peripheral end surface of the polarizing plate. And a part.

  The image display device preferably has an amount of color missing after holding at 85 ° C. and 85% RH environment for 120 hours, preferably 100 μm or less, more preferably 50 μm or less, further preferably 30 μm or less, and particularly preferably. Is 25 μm or less. The lower limit of the amount of color loss is preferably zero, and in one embodiment, 5 μm. After the image display device substitute (substantially, a polarizing plate with a substrate) was left in an oven at 85 ° C. and 85% RH for 120 hours to humidify, the color loss was changed to a state of crossed Nicols with the standard polarizing plate. The discolored state of the end portion at the time of disposition is examined with a microscope. Specifically, the size of the color loss from the end of the polarizing plate or the polarizing film (color loss: μm) is measured. As shown in FIG. 2, the larger of the color loss amount a from the end in the stretching direction and the color loss amount b from the end in the direction perpendicular to the stretching direction is defined as the color loss amount. The region where the color is missing has extremely low polarization characteristics and does not substantially function as a polarizing plate. Therefore, the smaller the amount of color loss, the better.

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

(1) Thickness The thickness was measured using a digital micrometer (KC-351C manufactured by Anritsu Corporation).
(2) Moisture Permeability Using the pressure-sensitive adhesive compositions prepared in Examples and Comparative Examples, a pressure-sensitive adhesive sheet having a configuration of release liner / pressure-sensitive adhesive layer (having the thickness of the examples or comparative examples) / release liner was formed. . One of the release liners of the pressure-sensitive adhesive sheet is peeled off to expose the pressure-sensitive adhesive surface, and the pressure-sensitive adhesive sheet is bonded to a triacetyl cellulose film (TAC film, thickness: 25 μm, manufactured by Konica Minolta Co., Ltd.) through the pressure-sensitive adhesive surface, and 10 cmΦ Cut out in a circle. Finally, the other release liner was peeled off to obtain a sample for measurement. The moisture permeability (water vapor permeability) of the obtained measurement sample was measured by a moisture permeability test method (cup method, according to JIS Z 0208). The measurement conditions were as follows. In the measurement, a thermo-hygrostat was used.
Measurement temperature: 40 ° C
Relative humidity: 92%
Measurement time: 24 hours (3) Amount of color omission After the polarizing plates with substrates obtained in Examples and Comparative Examples were left in an oven at 85 ° C. and 85% RH for 120 hours as a substitute for an image display device and humidified, When arranged in a crossed Nicols state with the standard polarizing plate, the state of color loss at the end of the polarizing film was examined with a microscope. Specifically, the size of color loss from the edge of the polarizing film (color loss amount: μm) was measured. Using an Olympus MX61L microscope, the amount of color loss was measured from an image taken at a magnification of 10 times. As shown in FIG. 2, the larger of the color loss amount a from the end in the stretching direction and the color loss amount b from the end in the direction perpendicular to the stretching direction was defined as the color loss amount.

[Example 1]
As a resin substrate, an amorphous polyethylene terephthalate (IPA copolymerized PET) film having a thickness of 100 μm and a Tg of 75 ° C. and having 7 mol% of isophthalic acid units was prepared. The surface of this film was subjected to a corona treatment (55 W / m ² / min).
An acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Gosefimer (registered trademark) Z200) and PVA (average degree of polymerization: 4200, degree of saponification: 99.2 mol%) were 1: 9. A PVA-based resin was prepared at a ratio, and 13 parts by weight of potassium iodide was 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). This aqueous solution is applied to the corona-treated surface of the resin substrate so that the film thickness after drying becomes 13 μm, and dried by hot-air drying at 60 ° C. for 10 minutes to form a 9 μm-thick PVA-based resin A resin layer was formed. Thus, a laminate was produced.
The obtained laminate was stretched 2.4 times in air at 120 ° C. (auxiliary stretching in air).
Next, the laminate was immersed in a boric acid aqueous solution at a liquid temperature of 40 ° C. for 30 seconds to insolubilize the PVA-based resin layer. The boric acid aqueous solution in this step had a boric acid content of 4 parts by weight based on 100 parts by weight of water.
Next, the laminate was immersed and dyed in a dyeing solution containing iodine and potassium iodide at a liquid temperature of 30 ° C. for an arbitrary time so that the obtained polarizing film had a single transmittance of about 42 to 45%. The dyeing solution uses water as a solvent, has an iodine concentration in the range of 0.1 to 0.4% by weight, a potassium iodide concentration in the range of 0.7 to 2.8% by weight, and has iodine and potassium iodide. Was 1: 7.
Next, the laminate was immersed in an aqueous solution of boric acid at 40 ° C. for 60 seconds to perform a crosslinking treatment on the PVA resin layer on which iodine was adsorbed. The boric acid aqueous solution in this step had a boric acid content of 5 parts by weight with respect to 100 parts by weight of water and a potassium iodide content of 3 parts by weight with respect to 100 parts by weight of water.
Further, the laminate was stretched 2.3 times in the same direction as the above-mentioned auxiliary in-air stretching at a stretching temperature of 70 ° C. in a boric acid aqueous solution (final stretching ratio of 5.50). The boric acid aqueous solution in this step had a boric acid content of 3.5 parts by weight with respect to 100 parts by weight of water and a potassium iodide content of 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 hot air at 60 ° C. to obtain a polarizing film having a thickness of 5 μm on a resin substrate. Was.

  A cycloolefin-based film (ZF-12, 23 μm, manufactured by Zeon Corporation) was bonded to the surface of the obtained polarizing film (the surface opposite to the resin substrate) via a UV-curable adhesive. Specifically, a UV curable adhesive was applied to each of the polarizing film and the cycloolefin-based film so as to have a total thickness of 1.0 μm, and was bonded using a roll machine. Thereafter, ultraviolet light was irradiated from the cycloolefin-based film side to cure the curable adhesive. Next, the resin substrate is peeled off, and a λ / 4 plate of a cycloolefin-based film (ZD-12, 23 μm thick, Re (550) = 140 nm, manufactured by Zeon Corporation) is applied to the peeled surface via a curable adhesive. To obtain a polarizing plate having a structure of cycloolefin-based film ZD-12 (protective film) / polarizing film / cycloolefin-based film ZF-12 (protective film). The ZD-12 film was bonded such that the slow axis was at an angle of 45 ° to the absorption axis of the polarizing film. This polarizing plate can be used, for example, as a viewing-side polarizing plate (anti-reflection film) of a reflective liquid crystal display device or an organic EL display device.

  The polarizing plate obtained above was cut into a size of 90 mm × 40 mm so that the absorption axis direction of the polarizing film was the long side direction. On the other hand, a commercially available glass plate (manufactured by Matsunami Glass Co., 0.4 mm thick) was cut into a 110 mm × 60 mm size as a substrate. The cut out polarizing plate and the cut out substrate were laminated via an acrylic pressure-sensitive adhesive. Here, the polarizing plate and the substrate were laminated such that the ZD-12 film (λ / 4 plate) of the polarizing plate was disposed on the substrate side. The polarizing plate and the substrate were laminated so that the substrate extended from all four sides constituting the outer periphery of the polarizing plate. The length of each of the four extending portions of the substrate was 10 mm.

  An adhesive was disposed on the extending portion, and the peripheral end surface of the polarizing plate was sealed. Thus, a sealing portion covering the peripheral end surface of the polarizing plate was formed. The pressure-sensitive adhesive constituting the sealing portion is based on 100 parts by weight of a block copolymer of styrene / ethylene propylene copolymer / styrene (manufactured by Kuraray Co., Ltd., trade name “Septon 2063”, styrene content: 13% by weight). 10 parts by weight of polybutene (trade name "Nisseki Polybutene HV-300" manufactured by JX Nippon Oil & Energy Corporation), 40 parts by weight of terpene phenol tackifier (trade name "YS Polystar TH130" manufactured by Yashara Chemical Co., Ltd.), and fragrance A group tackifier (manufactured by Eastman Chemical Co., Ltd., trade name “Picolastic A5”) was blended and produced.

Next, the pressure-sensitive adhesive and the substrate were irradiated with laser light, and the pressure-sensitive adhesive was cut so as to leave 100 μm from the peripheral edge of the polarizing plate, thereby forming a final sealing portion. The moisture permeability of the resulting sealing portion was ^12g / m 2 / 24hr. Irradiation with laser light was performed using "LaserPro Spirit" manufactured by GCC.

  As described above, a polarizing plate with a substrate was produced. The obtained polarizing plate with substrate was subjected to the evaluation of color loss described in (3) above. Table 1 shows the results. Further, FIG. 3 shows a state of color loss.

[Example 2]
A cycloolefin-based film (ZF-12, 13 μm, manufactured by Zeon Corporation) was adhered to the surface of the polarizing film of the laminate of the resin substrate / polarizing film obtained in the same manner as in Example 1 in the same manner as in Example 1. I matched. Next, the resin substrate is peeled off, and a reflective polarizer (APF-V3, manufactured by 3M) is attached to the peeled surface via an adhesive (12 μm), and the cycloolefin-based film ZF-12 (protective film) A polarizing plate having a configuration of / polarizing film / reflective polarizer was obtained. The reflective polarizer was attached so that the transmission axis of the polarizer was at an angle of 0 ° to the transmission axis of the polarizing film. This polarizing plate can be used, for example, as a rear-side polarizing plate.

  The following procedure was carried out in the same manner as in Example 1 to produce a polarizing plate with a substrate. Note that the polarizing plate and the substrate were laminated such that the ZF-12 film (protective film) of the polarizing plate was disposed on the substrate side. The obtained polarizing plate with substrate was subjected to the same evaluation as in Example 1. Table 1 shows the results.

[Example 3]
A cycloolefin-based film (ZF-12, 13 μm, manufactured by Zeon Corporation) was adhered to the surface of the polarizing film of the laminate of the resin substrate / polarizing film obtained in the same manner as in Example 1 in the same manner as in Example 1. I matched. Next, the resin substrate was peeled off to obtain a polarizing plate having a configuration of cycloolefin-based film ZF-12 (protective film) / polarizing film. The following procedure was carried out in the same manner as in Example 1 to produce a polarizing plate with a substrate. Note that the polarizing plate and the substrate were laminated such that the polarizing film was disposed on the substrate side. The obtained polarizing plate with substrate was subjected to the same evaluation as in Example 1. Table 1 shows the results.

[Example 4]
Moisture permeability was produced 24g ^/ m 2 / 24hr sealing portion is except for (having a thickness of 50 [mu] m) in the same manner as in Example 1 polarizing plate with the substrate. The obtained polarizing plate with substrate was subjected to the same evaluation as in Example 1. Table 1 shows the results.

[Example 5]
Moisture permeability was produced 24 g / m ^2/24 hr or sealing portion which is except for (having a thickness of 50 [mu] m) in the same manner as in Example 2 polarizer with substrate. The obtained polarizing plate with substrate was subjected to the same evaluation as in Example 1. Table 1 shows the results.

[Example 6]
Moisture permeability was produced 24g ^/ m 2 / 24hr sealing portion is except for (having a thickness of 50 [mu] m) in the same manner as in Example 3 polarizing plate with the substrate. The obtained polarizing plate with substrate was subjected to the same evaluation as in Example 1. Table 1 shows the results.

[Comparative Example 1]
A polarizing plate with a substrate was produced in the same manner as in Example 1 except that the sealing portion was not formed. The obtained polarizing plate with substrate was subjected to the same evaluation as in Example 1. Table 1 shows the results. Further, FIG. 4 shows a state of color loss.

[Comparative Example 2]
Sealing portion except for using an ordinary acrylic adhesive in the same manner as in Example 1 (moisture permeability: greater than 1000g ^/ m 2 / 24hr, thickness: 25 [mu] m) was formed, a polarizing plate was prepared with substrate . The obtained polarizing plate with substrate was subjected to the same evaluation as in Example 1. Table 1 shows the results.

  As is clear from Table 1, by forming a sealing portion having a predetermined moisture permeability on the outer peripheral end surface of the polarizing plate, a polarizing plate with a substrate capable of maintaining excellent optical characteristics even in a humid environment (finally, , An image display device).

  The image display device obtained by the manufacturing method of the present invention is applicable to televisions, displays, mobile phones, personal digital assistants, digital cameras, video cameras, portable game machines, car navigation systems, copiers, printers, faxes, watches, microwave ovens, and the like. It is preferably used.

DESCRIPTION OF SYMBOLS 10 Polarizer 20 Substrate 30 Sealing part 40 Sealing part (final)
100 Polarizing plate with substrate

Claims (9)

Preparing a polarizing plate and a substrate having a size larger than the polarizing plate,
Laminating the substrate and the polarizing plate so that the substrate extends from the outer periphery of the polarizing plate,
Forming a sealing portion covering a peripheral end surface of the polarizing plate; and cutting the substrate and the sealing portion to a predetermined size, leaving a portion extending a predetermined length from a peripheral end of the polarizing plate. And a method for manufacturing an image display device.   The method according to claim 1, wherein the substrate is a glass plate.   The method according to claim 1, wherein the substrate is a resin film.   4. The method according to claim 1, wherein the substrate and the polarizing plate are stacked such that the substrate extends from all four sides constituting the outer periphery of the polarizing plate. 5.   The method according to claim 1, wherein the substrate is a display cell substrate of an image display device selected from a liquid crystal display device, an organic EL display device, and a quantum dot display device.   The manufacturing method according to claim 1, wherein the cutting is performed by irradiating a laser beam.   The manufacturing method according to claim 1, wherein a length of the extended portion of the sealing portion after the cutting is 10 μm to 500 μm. The moisture permeability of the sealing portion after cutting is not more than 300g ^/ m 2 ^/ 24hr, the manufacturing method according to any one of claims 1 to 7. An image display device, comprising: a polarizing plate; a substrate having a portion extending a predetermined length from a peripheral end of the polarizing plate; and a sealing portion formed on the extending portion and covering a peripheral end surface of the polarizing plate.