WO2024084805A1 - Method for producing optical laminate - Google Patents

Method for producing optical laminate Download PDF

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Publication number
WO2024084805A1
WO2024084805A1 PCT/JP2023/030511 JP2023030511W WO2024084805A1 WO 2024084805 A1 WO2024084805 A1 WO 2024084805A1 JP 2023030511 W JP2023030511 W JP 2023030511W WO 2024084805 A1 WO2024084805 A1 WO 2024084805A1
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WIPO (PCT)
Prior art keywords
roller
optical film
lamination
laminate
film
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PCT/JP2023/030511
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French (fr)
Japanese (ja)
Inventor
忍 出▲崎▼
聖史 堂免
未来 白子
展明 岩本
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日東電工株式会社
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Publication of WO2024084805A1 publication Critical patent/WO2024084805A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H37/00—Article or web delivery apparatus incorporating devices for performing specified auxiliary operations
    • B65H37/04—Article or web delivery apparatus incorporating devices for performing specified auxiliary operations for securing together articles or webs, e.g. by adhesive, stitching or stapling
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements

Definitions

  • the present invention relates to a method for manufacturing an optical laminate having at least a polarizing plate.
  • the present invention relates to a method for manufacturing an optical laminate capable of suppressing curling.
  • polarizing plates have been used as a component material for liquid crystal display devices, organic EL display devices, and the like.
  • a polarizing plate includes a retardation film and the like depending on the application.
  • a polarizing film is composed of, for example, a polarizer dyed with a dichroic substance such as iodine and a protective film that protects the polarizer.
  • a long strip-shaped polarizing film is manufactured by laminating a long strip-shaped protective film to at least one side of a long strip-shaped polarizer.
  • a long strip-shaped retardation film and the like are laminated to one side of the manufactured long strip-shaped polarizing film to manufacture a long strip-shaped polarizing plate.
  • a long strip-shaped release liner is laminated to one side of the manufactured long strip-shaped polarizing plate, and a long strip-shaped surface protective film is laminated to the other side to manufacture a long strip-shaped optical laminate.
  • the lamination of each of these long strip-shaped films is usually performed by a roll-to-roll method.
  • the manufactured long strip-shaped optical laminate is cut to a size and shape depending on the application and used in a liquid crystal display device or the like. When used in a liquid crystal display device, the release liner is peeled off and the remaining components of the optical laminate are attached to the liquid crystal display device, etc.
  • the above optical laminates are generally manufactured by a manufacturing method that includes a polarizing film manufacturing process, a retardation film lamination process, a release liner lamination process, an inspection process, and a surface protection film lamination process.
  • a long strip of resin film is used as the raw film, which is transported in the longitudinal direction while being immersed in various treatment baths and subjected to various treatments such as dyeing and stretching to produce a long strip of polarizer.
  • a long strip of protective film is then attached to at least one side of the long strip of polarizer to produce a long strip of polarizing film.
  • phase difference film lamination process a long strip of phase difference film (such as a half-wave plate or a quarter-wave plate) is laminated to one side of a long strip of polarizing film to produce a long strip of polarizing plate.
  • a long strip of phase difference film such as a half-wave plate or a quarter-wave plate
  • adhesive is applied to a long strip of release liner while it is being transported in the longitudinal direction, and the applied adhesive is heated and dried in an oven or the like to harden it and form an adhesive layer.
  • the adhesive layer side of this long strip of release liner (release liner with adhesive layer) is then laminated to one side of a long strip of polarizing plate to produce a long strip of intermediate product in which a polarizing plate, adhesive layer, and release liner are laminated.
  • an adhesive layer is formed not only on the release liner but also on the polarizing plate, and the adhesive layer side of the release liner is laminated to the adhesive layer side of the polarizing plate to produce a long strip of intermediate product.
  • the release liner is peeled off while leaving the adhesive layer between the release liner and the polarizing plate on the polarizing plate side, and the polarizing plate is inspected.
  • Inspection methods for polarizing plates include transmission inspection, crossed Nicol inspection, and reflection inspection.
  • the peeled release liner is reattached to the polarizing plate (including attaching a new release liner different from the peeled one to the polarizing plate) to return it to its original intermediate state.
  • a long strip of surface protection film is laminated to the side of the long strip of polarizing plate opposite the side to which the release liner is laminated.
  • Patent Document 1 proposes using a specific material for a protective film that protects a polarizer as a method for suppressing curling of a polarizing film, but the material of the protective film is limited and is not versatile. A method capable of suppressing curling without particularly changing the materials of the components of a conventionally used optical laminate is desired.
  • the present invention was made to solve the problems of the conventional technology described above, and aims to provide a method for manufacturing an optical laminate that can suppress curling.
  • the present inventors conducted extensive research and found that in conventional methods for producing optical laminates, the surface material of the lamination roller and the approach angle of the film to the lamination roller in the lamination steps of various films (e.g., a release liner lamination step, a release liner re-lamination step in an inspection step, and a surface protection film lamination step) affect the curl value (an index representing the degree of curl) of the laminate after lamination.
  • the curl value in the direction (TD direction) perpendicular to the longitudinal direction (conveyance direction, MD direction) of the laminate after lamination changes depending on the angle at which the film contacting this roller (hereinafter referred to as the "resin roller” as appropriate) enters the lamination roller.
  • the present invention has been completed based on the above findings of the present inventors.
  • the present invention provides a method for manufacturing an optical laminate, which includes a step of bonding a long strip-shaped first optical film including a polarizing plate transported in a longitudinal direction and a long strip-shaped second optical film transported in a longitudinal direction, via an adhesive layer, by a bonding roller, the bonding roller being composed of a first roller that contacts the first optical film, and a second roller that is disposed opposite the first roller and contacts the second optical film, the first optical film and the second optical film are bonded together by entering between the first roller and the second roller, and the first roller
  • the surface of at least one of the lamination roller and the second roller is made of resin, and when the surface of the first roller is made of resin, the angle of entry of the first optical film into the lamination roller is adjusted so that the curl value in the direction perpendicular to the longitudinal direction of the laminate of the first optical film and the second optical film falls within a predetermined range, or when the surface of the second roller is made of resin, the angle of entry of the second
  • the "approach angle of the first optical film to the laminating roller” means an angle formed by a vector perpendicular to a line passing through the rotation centers of the first roller and the second roller that constitute the laminating roller, the vector perpendicular to the rotation center of the first roller and the rotation center of the second roller, and pointing toward the exit side of the laminating roller, and the vector that indicates the traveling direction of the first optical film until it comes into contact with the laminating roller, in a cross section perpendicular to the rotation center of the first roller and the rotation center of the second roller that constitute the laminating roller.
  • the "angle of entry of the second optical film into the laminating roller” means the angle formed by a vector perpendicular to a line passing through the centers of rotation of the first roller and the second roller that constitute the laminating roller, the vector perpendicular to the line passing through the centers of rotation of the first roller and the second roller and pointing toward the exit side of the laminating roller, and the vector indicating the direction of travel of the second optical film until it comes into contact with the laminating roller, in a cross section perpendicular to the centers of rotation of the first roller and the second roller that constitute the laminating roller.
  • the inventors when the first roller is a resin roller, by adjusting the angle of entry of the first optical film, which contacts the first roller, into the lamination roller, the inventors have discovered that the curl value in the TD direction of the laminate of the first optical film and the second optical film can be controlled within a predetermined range, and ultimately the curl value in the TD direction of the optical laminate can be suppressed to a level that does not cause problems in use.
  • the curl value in the TD direction of the laminate of the first optical film and the second optical film can be controlled within a predetermined range by adjusting the angle of entry of the second optical film, which contacts the second roller, into the lamination roller, and ultimately, the curl value in the TD direction of the optical laminate can be suppressed to a level that does not cause problems in use.
  • the surface of the first roller is made of resin. According to the above-mentioned preferred method, since the surface of the first roller that contacts the first optical film including the polarizing plate is a resin roller formed from resin, it is possible to suppress the occurrence of appearance defects such as scratches and dents on the polarizing plate.
  • a first transport roller that comes into contact with the first optical film is disposed on the entry side of the lamination roller, and the position of the first transport roller relative to the lamination roller is adjusted to adjust the angle of entry of the first optical film into the lamination roller; or, when the surface of the second roller is made of resin, a second transport roller that comes into contact with the second optical film is disposed on the entry side of the lamination roller, and the position of the second transport roller relative to the lamination roller is adjusted to adjust the angle of entry of the second optical film into the lamination roller.
  • the term "entrance side of the lamination roller” means the upstream side of the lamination roller in the transport direction of the first optical film or the second optical film. According to the above-described preferred configuration, the angle at which the first optical film or the second optical film approaches the lamination roller can be easily adjusted by adjusting the position of the first transport roller or the second transport roller.
  • the second optical film may be a release liner, and the surface of the second roller may be made of metal.
  • the second roller is a metal roller (hereinafter, a roller whose surface is formed from a metal such as iron will be referred to as a "metal roller" as appropriate)
  • the angle of entry of the first optical film into the lamination roller is adjusted so that the curl value in the TD direction of the laminate of the first optical film and the second optical film is within a predetermined range.
  • the second optical film may be a surface protection film.
  • the angle of entry of the first optical film into the lamination roller is adjusted to 75° or less (more preferably, 60° or less), or when the surface of the second roller is made of resin, the angle of entry of the second optical film into the lamination roller is adjusted to 75° or less (more preferably, 60° or less).
  • the surface of the first roller when the surface of the first roller is made of resin, it is preferable that the surface of the first roller is made of rubber, such as silicone rubber. Also, when the surface of the second roller is made of resin, it is preferable that the surface of the second roller is made of rubber, such as silicone rubber.
  • a method for producing an optical laminate comprising a step of laminating a long strip-shaped first optical film including a polarizing plate transported in a longitudinal direction and a long strip-shaped second optical film transported in the longitudinal direction, via an adhesive layer, by a laminating roller, the laminating roller being composed of a first roller that contacts the first optical film, and a second roller that is disposed opposite to the first roller and contacts the second optical film, the first optical film and the second optical film are laminated together by entering between the first roller and the second roller, and the first roller and the second roller are laminated together by the first roller and the second roller.
  • a surface of at least one of the laminating rollers is formed from resin, and when the surface of the first roller is formed from resin, an approach angle of the first optical film to the laminating roller is adjusted so that a curl value in a direction perpendicular to the longitudinal direction of the laminate of the first optical film and the second optical film falls within a predetermined range; or, when the surface of the second roller is formed from resin, an approach angle of the second optical film to the laminating roller is adjusted so that a curl value in a direction perpendicular to the longitudinal direction of the laminate of the first optical film and the second optical film falls within a predetermined range.
  • [7] A method for producing an optical laminate described in any of [1] to [6], wherein when the surface of the first roller is formed from resin, the surface of the first roller is formed from rubber, and when the surface of the second roller is formed from resin, the surface of the second roller is formed from rubber.
  • FIG. 1 is a cross-sectional view showing a schematic configuration of an optical laminate produced by a production method according to one embodiment of the present invention.
  • FIG. 1 is a flow diagram showing schematic steps of a method for producing an optical laminate according to one embodiment of the present invention.
  • 3 is a diagram illustrating an example of a schematic configuration of an apparatus for performing the release liner bonding step ST3 illustrated in FIG. 2.
  • FIG. 2 is an explanatory diagram for explaining an outline of a method for measuring a curl value.
  • 3 is a diagram showing an example of the results of measuring the curl value in the TD direction and the curl value in the MD direction of the laminate F3 (second intermediate M2) produced in the release liner attachment step ST3 shown in FIG. 2.
  • FIG. 1 is a cross-sectional view showing a schematic configuration of an optical laminate produced by a production method according to one embodiment of the present invention.
  • FIG. 1 is a flow diagram showing schematic steps of a method for producing an optical laminate according to one embodiment of the present invention.
  • 3
  • FIG. 13 is a diagram showing an example of the outline and results of a test conducted by the present inventors to investigate the relationship between the amount of roller deflection and the curl value in the TD direction.
  • 1 is a diagram showing an example of the outline and results of a test conducted by the present inventors to measure the position on the surface of a first optical film F1.
  • FIG. FIG. 1 is an explanatory diagram that illustrates the reason why the inventors speculate that the TD curl value of the laminate F3 after lamination changes depending on the approach angle ⁇ of the first optical film F1, which is in contact with the first roller R1a, which is a resin roller, to the lamination roller R1.
  • FIG. 13 is a diagram showing another example of the results of measuring the curl value in the TD direction and the curl value in the MD direction of the laminate F3 (second intermediate M2) produced in the release liner attachment step ST3 shown in FIG. 2.
  • 3 is a side view showing a schematic configuration example of an apparatus for bonding release liner 4 again to polarizing plate 10 in inspection step ST4 shown in FIG. 2.
  • FIG. 3 is a diagram showing an example of the results of measuring the curl value in the TD direction and the curl value in the MD direction of the laminate F3 (second intermediate M2) produced in the inspection process ST4 shown in FIG. 2.
  • 3 is a side view showing a schematic configuration example of an apparatus for performing the surface protective film bonding step ST5 shown in FIG. 2.
  • FIG. 3 is a diagram showing an example of the results of measuring the curl value in the TD direction of the laminate F3 (optical laminate 100) produced in the surface protective film attachment step ST5 shown in FIG. 2.
  • FIG. 3 is a side view showing a schematic configuration of another example of the schematic configuration of an apparatus for performing the surface protective film bonding step ST5 shown in FIG. 2 and a schematic configuration of an apparatus according to a reference example.
  • FIG. 3 is a diagram showing an example of the results of measuring the curl value in the TD direction of the laminate F3 (optical laminate 100) produced in the surface protective film attachment step ST5 shown in FIG. 2.
  • FIG. 3 is a diagram showing an example of the results of measuring the curl value in the TD direction of the laminate F3 (optical laminate 100) produced in the surface protective film attachment step ST5 shown in FIG. 2.
  • FIG. 1 is a cross-sectional view that illustrates a schematic configuration of an optical laminate produced by a production method according to this embodiment.
  • the optical laminate 100 of this embodiment includes a polarizing film 1, a retardation film 2, a pressure-sensitive adhesive layer 3, a release liner 4, and a surface protective film 5.
  • a laminate of the polarizing film 1 and the retardation film 2 constitutes a polarizing plate 10.
  • a laminate of the polarizing plate 10 and the pressure-sensitive adhesive layer 3 constitutes a first intermediate M1.
  • a laminate of the first intermediate M1 and the release liner 4 constitutes a second intermediate M2.
  • Each component of the optical laminate 100 will be described below.
  • the polarizing film 1 is composed of a polarizer 11 and protective films 12 and 13 that protect the polarizer 11.
  • the protective films 12 and 13 are bonded to both sides of the polarizer 11, but this is not limited thereto, and it is sufficient that a protective film is bonded to at least one side of the polarizer 11.
  • the polarizer 11 is typically made of a resin film containing a dichroic material.
  • the resin film any appropriate resin film that can be used as a polarizer can be adopted.
  • the resin film is typically a polyvinyl alcohol-based resin (hereinafter, referred to as a "PVA-based resin”) film.
  • Any suitable resin can be used as the PVA-based resin that forms the PVA-based resin film.
  • suitable resin examples include polyvinyl alcohol and ethylene-vinyl alcohol copolymer.
  • Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate.
  • Ethylene-vinyl alcohol copolymer can be obtained by saponifying ethylene-vinyl acetate copolymer.
  • 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 1,000 to 10,000, preferably 1,200 to 4,500, and more preferably 1,500 to 4,300.
  • the average degree of polymerization can be determined in accordance with JIS K 6726-1994.
  • dichroic substances contained in the resin film include iodine and organic dyes. These can be used alone or in combination of two or more. Iodine is preferably used.
  • the resin film may be a single-layer resin film or a laminate of two or more layers.
  • a specific example of a polarizer made of a single-layer resin film is a PVA-based resin film that has been dyed with iodine and stretched (typically, uniaxially stretched).
  • the dyeing with iodine is performed, for example, by immersing the PVA-based film in an aqueous iodine solution.
  • the stretching ratio for uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after dyeing or while dyeing. Dyeing may also be performed after stretching. If necessary, the PVA-based resin film may be subjected to swelling, crosslinking, washing, drying, etc.
  • polarizers made of a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer made of a laminate of a resin substrate and a PVA-based resin layer applied to the resin substrate.
  • a polarizer made of a laminate of a resin substrate and a PVA-based resin layer applied to the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate, drying the resin substrate to form a PVA-based resin layer on the resin substrate, obtaining a laminate of the resin substrate and the PVA-based resin layer, and then stretching and dyeing the laminate to make the PVA-based resin layer into a polarizer.
  • stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may include, as necessary, stretching the laminate in air at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution.
  • the obtained resin substrate/polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate/polarizer laminate, and any suitable protective layer may be laminated on the peeled surface depending on the purpose. Details of the method for producing such a polarizer are described, for example, in JP 2012-73580 A. The entire disclosure of this publication is incorporated herein by reference.
  • the thickness of the polarizer 11 is preferably 15 ⁇ m or less, more preferably 1 ⁇ m to 12 ⁇ m, even more preferably 3 ⁇ m to 10 ⁇ m, and particularly preferably 3 ⁇ m to 8 ⁇ m.
  • the polarizer 11 preferably exhibits absorption dichroism at any wavelength within the range of 380 nm to 780 nm.
  • the single transmittance of the polarizer 11 is preferably 40.0% to 45.0%, and more preferably 41.5% to 43.5%.
  • the degree of polarization of the polarizer 11 is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.
  • any suitable resin film is used as the protective films 12 and 13.
  • materials for forming the resin film include (meth)acrylic resins, cellulose resins such as diacetyl cellulose and triacetyl cellulose, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, ester resins such as polyethylene terephthalate resins, polyamide resins, polycarbonate resins, and copolymer resins thereof.
  • (meth)acrylic resin means acrylic resin and/or methacrylic resin.
  • the materials for forming the protective films 12 and 13 may be the same or different from each other.
  • the thickness of the protective films 12 and 13 is typically 10 ⁇ m to 100 ⁇ m, and preferably 20 ⁇ m to 40 ⁇ m.
  • the thicknesses of the protective films 12 and 13 may be the same or different.
  • the surface of the protective films 12, 13 opposite the polarizer 11 may be subjected to a surface treatment such as a hard coat treatment, an anti-reflection treatment, an anti-sticking treatment, or an anti-glare treatment, if necessary. Furthermore, the surface of the protective films 12, 13 opposite the polarizer 11 may be subjected to a treatment to improve visibility when viewed through polarized sunglasses (typically, a treatment to impart an (elliptical) polarizing function or a treatment to impart an ultra-high phase difference), if necessary. Note that when a surface treatment is performed to form a surface treatment layer, the thickness of the protective films 12, 13 includes the thickness of the surface treatment layer.
  • the protective films 12 and 13 are laminated by being attached to the polarizer 11 via any suitable adhesive layer (not shown).
  • suitable adhesive layer include a PVA-based adhesive or an activated energy ray curing adhesive.
  • the retardation film 2 may be, for example, a compensation plate that provides a wide viewing angle, or a retardation plate (circular polarizing plate) such as a half-wave plate or a quarter-wave plate that is used together with a polarizing film to generate circularly polarized light.
  • the thickness of the retardation film 2 is, for example, 1 to 200 ⁇ m.
  • the retardation film 2 is formed of, for example, a layer or resin formed by polymerizing a polymerizable liquid crystal.
  • the polymerizable liquid crystal is a compound having a polymerizable group and liquid crystallinity.
  • the polymerizable group means a group involved in a polymerization reaction, and is preferably a photopolymerizable group.
  • the photopolymerizable group means a group that can be involved in a polymerization reaction by an active radical or an acid generated from a photopolymerization initiator.
  • Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group.
  • an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferable, and an acryloyloxy group is more preferable.
  • the liquid crystallinity of the polymerizable liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, and when the thermotropic liquid crystal is classified by the degree of order, it may be a nematic liquid crystal or a smectic liquid crystal.
  • the resin forming the retardation film 2 include polyarylate, polyamide, polyimide, polyester, polyaryletherketone, polyamideimide, polyesterimide, polyvinyl alcohol, polyfumaric acid ester, polyethersulfone, polysulfone, norbornene resin, polycarbonate resin, cellulose resin, and polyurethane. These resins may be used alone or in combination.
  • the retardation film 2 is laminated by being attached to the polarizing film 1 (protective film 13) via any suitable adhesive layer or pressure sensitive adhesive layer (not shown).
  • suitable adhesive layer or pressure sensitive adhesive layer include a PVA-based adhesive or an activated energy ray curing adhesive.
  • the adhesive layer 3 is formed by applying an adhesive to one side of the release liner 4 and then heating and drying the applied adhesive in an oven or the like to harden it. In some cases, the adhesive layer 3 is formed not only on the release liner 4 but also on the retardation film 2 constituting the polarizing plate 10.
  • the heating temperature of the adhesive is preferably set in the range of 100° C. to 160° C., and more preferably in the range of 140° C. to 160° C. Heating at this heating temperature is preferably performed for 20 seconds to 3 minutes, and more preferably for 1 minute to 3 minutes.
  • adhesives forming the adhesive layer 3 include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives.
  • an adhesive having the desired properties according to the purpose can be prepared.
  • the base resin of the adhesive may be used alone or in combination of two or more types. From the viewpoints of transparency, processability, durability, etc., acrylic adhesives are preferred. Details of the adhesives constituting the adhesive layer are described, for example, in JP 2014-115468 A, and the description of this publication is incorporated by reference in this specification.
  • the thickness of the adhesive layer can be, for example, 10 ⁇ m to 100 ⁇ m.
  • release liner 4 Any appropriate release liner can be used as the release liner 4.
  • Specific examples include plastic films, nonwoven fabrics, or papers whose surfaces are coated with a release agent.
  • Specific examples of release agents include silicone-based release agents, fluorine-based release agents, and long-chain alkyl acrylate-based release agents.
  • Specific examples of plastic films include polyethylene terephthalate (PET) films, polyethylene films, and polypropylene films.
  • PET polyethylene terephthalate
  • the thickness of the release liner 4 can be, for example, 10 ⁇ m to 100 ⁇ m.
  • the surface protection film 5 typically has a substrate and a pressure-sensitive adhesive layer.
  • the thickness of the surface protection film 5 is, for example, 30 ⁇ m or more.
  • the upper limit of the thickness of the surface protection film 5 is, for example, 150 ⁇ m.
  • the "thickness of the surface protection film” refers to the total thickness of the substrate and the pressure-sensitive adhesive layer.
  • the substrate can be made of any suitable resin film.
  • Materials for forming the resin film include ester-based resins such as polyethylene terephthalate-based resins, cycloolefin-based resins such as norbornene-based resins, olefin-based resins such as polypropylene, polyamide-based resins, polycarbonate-based resins, and copolymer resins of these. Ester-based resins (particularly polyethylene terephthalate-based resins) are preferred.
  • any suitable adhesive can be used as the adhesive that forms the adhesive layer.
  • the base resin of the adhesive include acrylic resin, styrene resin, silicone resin, urethane resin, and rubber resin.
  • FIG. 2 is a flow diagram showing an outline of the steps of a method for producing the optical laminate 100 according to this embodiment.
  • the manufacturing method according to the present embodiment includes a polarizing film manufacturing process ST1, a retardation film bonding process ST2, a release liner bonding process ST3, an inspection process ST4, and a surface protection film bonding process ST5.
  • a polarizing film manufacturing process ST1 a retardation film bonding process ST2
  • a release liner bonding process ST3 an inspection process ST4
  • a surface protection film bonding process ST5 Each of the processes ST1 to ST5 will be described below.
  • polarizing film manufacturing process ST1 In the polarizing film manufacturing process ST1, a long strip-shaped resin film is used as a raw film, and this raw film is immersed in various treatment baths while being transported in the longitudinal direction (MD direction) and subjected to various treatments such as dyeing and stretching to manufacture a long strip-shaped polarizer 11. Then, long strip-shaped protective films 12 and 13 are bonded to the long strip-shaped polarizer 11 to manufacture a long strip-shaped polarizing film 1.
  • retardation film bonding process ST2 In the retardation film laminating step ST2, a long strip of retardation film 2 is laminated to one surface (protective film 13) of a long strip of polarizing film 1, thereby producing a long strip of polarizing plate 10.
  • the retardation film bonding step ST2 is not necessary.
  • release liner attachment step ST3 In the release liner laminating step ST3, an adhesive is applied to the long strip release liner 4 while it is being transported in the longitudinal direction (MD direction), and the applied adhesive is heated in an oven or the like to dry and harden, thereby forming an adhesive layer 3. Then, the release liner 4 is bonded to the long strip polarizing plate 10 via the adhesive layer 3 formed on the long strip release liner 4. Specifically, the adhesive layer 3 side of the long strip release liner 4 (release liner 4 with adhesive layer 3) is bonded to one side (phase difference film 2) of the long strip polarizing plate 10. In this way, a second intermediate M2 in which the polarizing plate 10, the adhesive layer 3, and the release liner 4 are laminated is manufactured.
  • the pressure-sensitive adhesive layer 3 may be formed not only on the release liner 4 but also on the retardation film 2 constituting the polarizing plate 10 to obtain a polarizing plate 10 with a pressure-sensitive adhesive layer 3. Then, the pressure-sensitive adhesive layer 3 side of the release liner 4 and the pressure-sensitive adhesive layer side of the polarizing plate 10 can be bonded together to produce the second intermediate M2.
  • Figure 3 is a schematic diagram showing an example of the schematic configuration of an apparatus for performing the release liner lamination step ST3.
  • Figure 3(a) is a side view of the apparatus (viewed from a horizontal direction (TD direction) perpendicular to the conveying direction (MD direction) of each film). The arrows shown in Figure 3(a) indicate the conveying direction of each film.
  • Figure 3(b) is a side view cross-sectional view explaining the approach angle of the film in the lamination roller R1 shown in Figure 3(a).
  • one of the films to be bonded by the lamination roller is the first optical film F1, and the other film is the second optical film F2.
  • the first optical film F1 is a polarizing plate 10 or a polarizing plate 10 with a pressure-sensitive adhesive layer 3
  • the second optical film F2 is a release liner 4 with a pressure-sensitive adhesive layer 3.
  • the first optical film F1 and the second optical film F2 are bonded together by the lamination roller R1 via the pressure-sensitive adhesive layer 3 to produce a laminate F3 of the first optical film F1 and the second optical film F2.
  • the laminate F3 is the second intermediate M2.
  • a first transport roller R2 in contact with the first optical film F1 is disposed on the entry side of the lamination roller R1 (upstream side in the transport direction of the first optical film F1 with respect to the lamination roller R1, and to the left of the lamination roller R1 in the example shown in Fig. 3(a)), and the first optical film F1 is transported to the lamination roller R1 by the first transport roller R2.
  • a second transport roller R3 in contact with the second optical film F2 is disposed on the entry side of the lamination roller R1 (upstream side in the transport direction of the second optical film F2 with respect to the lamination roller R1, and to the left of the lamination roller R1 in the example shown in Fig.
  • the second transport roller R3 transports the second optical film F2 to the lamination roller R1.
  • the position of the first conveying roller R2 relative to the lamination roller R1 is adjustable.
  • the first conveying roller R2 can move from the uppermost position shown by the solid line, through the position shown by the dashed line, to the lowermost position shown by the dashed line.
  • a configuration can be adopted in which the rotation shaft of the first conveying roller R2 is attached to a single-axis actuator via a bearing, and the position of the first conveying roller R2 can be adjusted by driving the single-axis actuator.
  • the second transport roller R3 is fixed at a predetermined position.
  • the lamination roller R1 is composed of a first roller R1a and a second roller R1b disposed opposite the first roller R1a (opposing in the vertical direction in the example shown in FIG. 3).
  • the first roller R1a is a roller that comes into contact with the first optical film F1 and transports the first optical film F1 between the first roller R1a and the second roller R1b.
  • the first roller R1a is a resin roller whose surface is made of resin (silicone rubber in this embodiment).
  • the second roller R1b is a roller that comes into contact with the second optical film F2 and transports the second optical film F2 between the first roller R1a and the second roller R1b.
  • the second roller R1b is a metal roller whose surface is made of metal (iron in this embodiment).
  • the first optical film F1 and the second optical film F2 enter between the first roller R1a and the second roller R1b, whereby the first optical film F1 and the second optical film F2 are bonded together to produce a laminate F3 of the first optical film F1 and the second optical film F2.
  • the laminate F3 is transported by a transport roller R4 and taken up by a take-up roller (not shown).
  • a straight line (virtual line) passing through the rotation center C1 of the first roller R1a and the rotation center C2 of the second roller is defined as a straight line CL.
  • a vector (virtual vector) perpendicular to the straight line CL and directed toward the exit side of the lamination roller R1 (the downstream side in the conveying direction of the first optical film F1 and the second optical film F2, and in the example shown in FIG. 3B, the right side of the lamination roller R1) is defined as a vector VC.
  • the approach angle ⁇ of the first optical film F1 to the lamination roller R1 means the angle formed by the vector VC and the vector indicating the traveling direction of the first optical film F1 until it contacts the lamination roller R1.
  • the approach angle ⁇ of the second optical film F2 to the lamination roller R1 means the angle formed by the vector VC and the vector indicating the traveling direction of the second optical film F2 until it contacts the lamination roller R1.
  • the approach angle ⁇ of the first optical film F1 to the lamination roller R1 is adjusted so that the curl value in the direction (TD direction) perpendicular to the longitudinal direction (MD direction) of the laminate F3 falls within a predetermined range.
  • the approach angle ⁇ is adjusted by adjusting the position of the first transport roller R2 relative to the lamination roller R1 in the vertical direction.
  • the approach angle ⁇ is the smallest, 0°, and when the first transport roller R2 is located at the bottom position shown by the dashed line, the approach angle ⁇ is the largest.
  • FIG. 4 is an explanatory diagram for explaining an outline of the method for measuring the curl value implemented in this embodiment.
  • a plurality of rectangular second intermediate samples M21 of product size for example, long side 160 mm ⁇ short side 80 mm used for smartphones
  • three intermediate samples M21 are shown, but in reality, this is not limited to this.
  • the curl value is measured for a total of 100 second intermediate samples M21 obtained by performing this for a plurality of second intermediates M2. Note that, as shown in FIG.
  • the second intermediate sample M21 when cutting out the second intermediate sample M21, the second intermediate sample M21 is cut out obliquely so that the MD direction of the second intermediate M2 (corresponding to the direction of the absorption axis of the polarizer 11 shown in FIG. 1) is at 45° to the long side and short side of the second intermediate sample M21.
  • the second intermediate sample M21 when measuring the curl value, is placed on a flat mounting table 20 so that the bottom side of the second intermediate sample M21 is convex (so that the warping of the four corners of the second intermediate sample M21 faces vertically upward), and the vertical distance H from the upper surface of the mounting table 20 to each of the four corners of the second intermediate sample M21 is measured.
  • the four corners of the second intermediate sample M21 are corners TD1 and TD2 located at both ends of the second intermediate M2 in the TD direction and corners MD1 and MD2 located at both ends of the second intermediate M2 in the MD direction before being cut out from the second intermediate M2.
  • the distance H is measured by erecting a scale extending vertically near the corners of the second intermediate sample M21 and visually reading the graduations of this scale.
  • the side where the release liner 4 of the second intermediate sample M21 is located is the bottom (the side where the polarizing plate 10 is located is the top), which is regarded as a positive curl, and the larger of the distances H measured for each of the corners TD1 and TD2 is calculated as the curl value in the TD direction. Also, the larger of the distances H measured for each of the corners MD1 and MD2 is calculated as the curl value in the MD direction.
  • the second intermediate sample M21 when the second intermediate sample M21 is placed on the mounting table 20 so that the bottom side is convex, the side of the second intermediate sample M21 where the release liner 4 is located is on the top (the side where the polarizing plate 10 is located is on the bottom), which is regarded as a negative curl, and the distance H measured for each of the corners TD1 and TD2 is multiplied by -1, and the larger absolute value is calculated as the curl value in the TD direction. Also, the distance H measured for each of the corners MD1 and MD2 is multiplied by -1, and the larger absolute value is calculated as the curl value in the MD direction.
  • the average of the TD curl values measured for each of the 100 second intermediate samples M21 is defined as the TD curl value of the second intermediate M2.
  • the average of the MD curl values measured for each of the 100 second intermediate samples M21 is defined as the MD curl value of the second intermediate M2.
  • the curl value in the TD direction and the curl value in the MD direction of the optical laminate 100 described later can also be measured by the same measurement method as described above with reference to FIG.
  • Fig. 5 is a diagram showing an example of the results of measuring the curl value in the TD direction and the curl value in the MD direction of the laminate F3 (second intermediate M2) produced in the release liner lamination step ST3.
  • Fig. 5 shows the results of measuring the curl value of the laminate F3 (second intermediate M2) having a total thickness of 117 ⁇ m, in which the first optical film F1 is a polarizing plate 10, the second optical film F2 is a release liner 4 with a pressure-sensitive adhesive layer 3, and is laminated in the following order.
  • the results shown in Fig. 5 were obtained when the approach angle ⁇ of the second optical film F2 to the lamination roller R1 was 43°.
  • Polarizing plate 10 (total thickness 65 ⁇ m) (1-1)
  • Protective film 12 Cycloolefin-based protective film (total thickness 29 ⁇ m) with a hard coat layer (thickness 3 ⁇ m)
  • Polarizer 11 Polyvinyl alcohol polarizer (thickness 13 ⁇ m)
  • Protective film 13 Triacetyl cellulose-based protective film (thickness 20 ⁇ m)
  • Retardation film 2 a laminate (total thickness 3 ⁇ m) of a polymerizable liquid crystal type 1 ⁇ 2 wavelength plate (thickness 1 ⁇ m) and a polymerizable liquid crystal type 1 ⁇ 4 wavelength plate (thickness 2 ⁇ m)
  • Pressure-sensitive adhesive layer 3 Acrylic pressure-sensitive adhesive layer (thickness 14 ⁇ m)
  • Release liner 4 polyethylene terephthalate release liner (thickness 38 ⁇ m)
  • the first roller R1a is a resin roller, and the curl value in the MD direction of the laminate F3 after lamination is approximately constant, while the curl value in the TD direction changes, depending on the approach angle ⁇ of the first film F1 that contacts this first roller R1a to the lamination roller R. Therefore, by adjusting the approach angle ⁇ of the first optical film F1 in contact with the first roller R1a to the lamination roller R1 so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, the TD curl value of the laminate F3 after lamination can be controlled within a predetermined range, and the TD curl value of the finally manufactured optical laminate 100 can be suppressed to a level that does not cause problems in use.
  • the inventors have investigated the reason why the curl value in the TD direction of the laminate F3 after lamination changes depending on the angle of entry ⁇ of the first optical film F1, which contacts the first roller R1a, a resin roller, into the lamination roller R1. The following describes the findings of the inventors.
  • FIG. 6 is a diagram showing an example of the outline and results of a test conducted by the present inventors to investigate the relationship between the amount of roller deflection and the curl value in the TD direction.
  • FIG. 6(a) is a front view (viewed from the conveying direction (MD direction) of each film) showing a state in which no load is applied to the first roller R1a in this test.
  • FIG. 6(b) is a front view showing a state in which a load is applied to the first roller R1a in this test.
  • FIG. 6(c) is a diagram showing an example of the results of measuring the position of the surface (lower surface) of the first roller R1a in this test.
  • FIG. 6(d) is a side view cross-sectional view explaining the amount of roller deflection.
  • FIG. 6(e) is a diagram showing an example of the results of this test.
  • the film is omitted from the illustration.
  • the inventors arranged multiple one-dimensional laser distance meters 20a along the rotation center C1 of the first roller R1a so as to face the surface (lower surface) of the first roller R1a with no load applied to the first roller R1a (a state in which the first roller R1a and the second roller R1b are in contact with each other without load via a film not shown), and measured the distance La from each one-dimensional laser distance meter 20a to the surface (lower surface) of the first roller R1a.
  • the one-dimensional laser distance meter 20a is a device that irradiates a spot-shaped laser beam and measures the distance to the irradiation position based on the principle of triangulation.
  • the inventors arranged multiple one-dimensional laser distance meters 20b facing the surface (upper surface) of the second roller R1b along the rotation center C2 of the second roller R1b with no load applied to the first roller R1a, and measured the distance Lb from each one-dimensional laser distance meter 20b to the surface (upper surface) of the second roller R1b.
  • the one-dimensional laser distance meter 20b is the same device as the one-dimensional laser distance meter 20a.
  • the separation distance L is considered to be approximately constant.
  • the inventors applied a load F to the first roller R1a from the state shown in Fig. 6(a), and measured the distance La' from each one-dimensional laser range finder 20a to the surface (lower surface) of the first roller R1a and the distance Lb' from each one-dimensional laser range finder 20b to the surface (upper surface) of the second roller R1b in the same manner as described above.
  • the load F applied to the rotation axis R11 of the first roller R1a was changed to various values, and the distances La' and Lb' were measured with each load F applied.
  • the separation distance L0 between the one-dimensional laser rangefinder 20a and the one-dimensional laser rangefinder 20b which is a known value, and the measured distances La' and Lb'
  • FIG. 6(c) plots the position of the first roller R1a in the direction of the rotation center C1, which corresponds to the TD direction of the first optical film F1, with a predetermined position as the reference value (0 mm).
  • FIG. 6(c) plots the displacement of the distance La' measured with no load applied to the first roller R1a from the reference value (0 mm) as the position of the surface (lower surface) of the first roller R1a.
  • the vertical axis of FIG. 6(c) is a positive value, it means that the position of the surface of the first roller R1a is closer to the one-dimensional laser distance meter 20a than the reference value.
  • the vertical axis of FIG. 6(c) is a negative value, it means that the position of the surface of the first roller R1a is farther from the one-dimensional laser distance meter 20a than the reference value.
  • the separation distance L' is smaller at the ends of the first roller R1a than at the center, and therefore the roller deformation amount ⁇ L is larger at the ends of the first roller R1a than at the center.
  • a load needs to be applied to the first roller R1a.
  • the release liner lamination process ST3 therefore, the state shown in FIG. 6(b) is reached, and it is considered that the roller deformation amount ⁇ L is larger at the ends of the first roller R1a than at the center.
  • the central angle ⁇ can be calculated by measuring the nip width, which is expressed as r ⁇ , using a known press scale or digitip. The inventors calculated the roller deflection ⁇ by removing the effect of the roller crush amount h from the roller deformation amount ⁇ L.
  • the load F applied was changed to three values, 0.13 MPa, 0.20 MPa, and 0.25 MPa, in terms of pressure.
  • the load F applied was changed to four values, 0.06 MPa, 0.10 MPa, 0.20 MPa, and 0.30 MPa, in terms of pressure.
  • FIG. 6(e) which shows an example of the results of this test, plots the average value of the roller deflection ⁇ calculated at three locations.
  • Fig. 7 is a diagram showing an example of the outline and results of a test conducted by the present inventors to measure the surface position of the first optical film F1.
  • Fig. 7(a) is a perspective view that shows a schematic outline of the test.
  • Fig. 7(b) is a side view that shows a schematic outline of the test.
  • Fig. 7(c) is a diagram showing an example of the surface position of the first optical film F1 measured at position P1 shown in Fig. 7(b).
  • FIG. 7(d) is a diagram showing an example of the surface position of the first optical film F1 measured at position P2 shown in Fig. 7(b).
  • the inventors arranged two two-dimensional laser distance meters 30a and 30b so as to face the surface (upper surface) of the first optical film F1, and moved each of the two-dimensional laser distance meters 30a and 30b along the TD direction of the first optical film F1 to measure the distance from each of the two-dimensional laser distance meters 30a and 30b to the surface (upper surface) of the first optical film F1.
  • the two-dimensional laser distance meters 30a and 30b are devices that irradiate a linear laser beam and measure the distance to the irradiation position based on the principle of triangulation.
  • each of the two-dimensional laser rangefinders 30a, 30b used in this test was approximately 210 mm, which is smaller than the dimension of the first optical film in the TD direction.
  • each of the two-dimensional laser rangefinders 30a, 30b was moved in the TD direction of the first optical film F1 along the TD direction of the first optical film F1, thereby measuring the distance to the surface of the first optical film F1 over the entire TD direction of the first optical film F1.
  • the two-dimensional laser distance meters 30a and 30b were placed at positions facing the surface of the first optical film F1 at a position (position P1 shown in FIG. 7(b)) immediately before the first optical film F1 contacted the first roller R1a, and at a position (position P2 shown in FIG. 7(b)) after the first optical film F1 contacted the first roller R1a, and the distance to the surface of the first optical film F1 was measured at each of the positions P1 and P2.
  • the load F applied to the first roller R1a was changed to four loads, 0.00 MPa, 0.13 MPa, 0.20 MPa, and 0.30 MPa in terms of pressure, and the distance to the surface of the first optical film F1 at each of the positions P1 and P2 was measured for each load F.
  • the horizontal axis plots the TD position of the first optical film F1 with a predetermined position as the reference value (0 mm). Also, the vertical axis of FIG. 7(c) and FIG. 7(d) plots the displacement of the measured distance from the reference value as the surface position of the first optical film F1 with a predetermined distance as the reference value (0 mm).
  • the vertical axis of FIG. 7(c) and FIG. 7(d) is a positive value, it means that the surface position of the first optical film F1 is closer to the two-dimensional laser distance meters 30a and 30b than the predetermined reference value.
  • the vertical axis of FIG. 7(c) and FIG. 7(d) is a negative value, it means that the surface position of the first optical film F1 is farther from the two-dimensional laser distance meters 30a and 30b than the predetermined reference value.
  • FIG. 8 is an explanatory diagram that illustrates, as inferred by the inventors based on the above results, why the curl value in the TD direction of the laminate F3 after lamination changes depending on the approach angle ⁇ of the first optical film F1, which is in contact with the first roller R1a, which is a resin roller, into the lamination roller R1.
  • the center of rotation C1 of the first roller R1a is bent downwardly convexly.
  • the amount of slack in the first optical film F1 immediately before contacting the first roller R1a becomes too large, a gap may occur between the first optical film F1 and the second optical film F2, preventing them from being properly bonded together, or wrinkles or crumples may occur in the laminate F3.
  • Fig. 9 is a diagram showing another example of the results of measuring the curl value in the TD direction and the curl value in the MD direction of the laminate F3 (second intermediate M2) produced in the release liner lamination step ST3.
  • Fig. 9 shows the results of measuring the curl value of the laminate F3 (second intermediate M2) having the same configuration as the example shown in Fig. 5, except that the first optical film F1 is a polarizing plate 10 with a pressure-sensitive adhesive layer 3 (thickness 14 ⁇ m) and has a total thickness of 131 ⁇ m.
  • the results shown in Fig. 9 were obtained when the approach angle ⁇ of the second optical film F2 to the lamination roller R1 was 43°.
  • the curl value in the MD direction of the laminate F3 after lamination is approximately constant, while the curl value in the TD direction changes depending on the approach angle ⁇ of the first film F1 to the lamination roller R. Therefore, by adjusting the approach angle ⁇ of the first optical film F1 in contact with the first roller R1a to the lamination roller R1 so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, the TD curl value of the laminate F3 after lamination can be controlled within a predetermined range, and the TD curl value of the finally manufactured optical laminate 100 can be suppressed to a level that does not cause problems in use. Specifically, data such as that shown in Fig.
  • the approach angle ⁇ of the first optical film F1 in contact with the first roller R1a to the lamination roller R1 is adjusted so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, and after the adjustment, the TD curl value of the laminate F3 after lamination can be controlled within a predetermined range.
  • the long strip-shaped release liner 4 is peeled off from the adhesive layer 3 (only the release liner 4 is peeled off while the adhesive layer 3 interposed between the release liner 4 and the polarizing plate 10 is left on the polarizing plate 10 side), and then the polarizing plate 10 (first intermediate M1) is inspected.
  • known inspection methods such as a transmission inspection, a crossed Nicol inspection, and a reflection inspection can be mentioned as the inspection method for the polarizing plate 10.
  • the peeled release liner 4 is bonded again to the polarizing plate 10 (including bonding a new release liner 4 different from the peeled release liner 4 to the polarizing plate 10) to return it to the original state of the second intermediate M2.
  • FIG. 10 is a side view (as viewed from the horizontal direction (TD direction) perpendicular to the conveying direction (MD direction) of each film) showing a schematic configuration example of an apparatus for bonding the release liner 4 again to the polarizing plate 10 in the inspection process ST4.
  • the arrows shown in FIG. 10 indicate the conveying direction of each film.
  • one of the films bonded by the lamination roller is the first optical film F1
  • the other film is the second optical film F2.
  • the first optical film F1 is the first intermediate M1 (polarizing plate 10 and adhesive layer 3) after inspection
  • the second optical film F2 is the release liner 4 (the peeled release liner 4 or the new release liner 4).
  • the first optical film F1 and the second optical film F2 are bonded together by the lamination roller R5 via the adhesive layer 3 to produce a laminate F3 of the first optical film F1 and the second optical film F2.
  • the laminate F3 is the second intermediate M2.
  • a first transport roller R6 in contact with the first optical film F1 is disposed on the entry side of the lamination roller R5 (upstream side in the transport direction of the first optical film F1 with respect to the lamination roller R5, and above the lamination roller R5 in the example shown in Fig. 10), and the first optical film F1 is transported to the lamination roller R5 by the first transport roller R6.
  • a second transport roller R7 in contact with the second optical film F2 is disposed on the entry side of the lamination roller R5 (upstream side in the transport direction of the second optical film F2 with respect to the lamination roller R5, and above the lamination roller R5 in the example shown in Fig.
  • the position of the first conveying roller R6 relative to the lamination roller R5 (in this embodiment, the horizontal position) is adjustable.
  • the first conveying roller R6 can move from the rightmost position shown by the solid line, through the position shown by the dashed line, to the leftmost position shown by the dashed line.
  • a configuration can be adopted in which the rotation shaft of the first conveying roller R6 is attached to a single-axis actuator via a bearing, and the position of the first conveying roller R6 can be adjusted by driving the single-axis actuator.
  • the second transport roller R7 is fixed at a predetermined position.
  • the lamination roller R5 is composed of a first roller R5a and a second roller R5b disposed opposite the first roller R5a (opposing in the horizontal direction in the example shown in FIG. 10).
  • the first roller R5a is a roller that comes into contact with the first optical film F1 and transports the first optical film F1 between the first roller R5a and the second roller R5b.
  • the first roller R5a is a resin roller whose surface is made of resin (silicone rubber in this embodiment).
  • the second roller R5b is a roller that comes into contact with the second optical film F2 and transports the second optical film F2 between the first roller R5a and the second roller R5b.
  • the second roller R5b is a metal roller whose surface is made of metal (iron in this embodiment).
  • the first optical film F1 and the second optical film F2 enter between the first roller R5a and the second roller R5b, whereby the first optical film F1 and the second optical film F2 are bonded together to produce a laminate F3 of the first optical film F1 and the second optical film F2.
  • the laminate F3 is transported by the transport roller R8 and taken up by a take-up roller (not shown).
  • the approach angle ⁇ of the first optical film F1 to the lamination roller R5 is adjusted so that the TD curl value of the laminate F3 falls within a predetermined range.
  • the meaning of the approach angle ⁇ is the same as that explained with reference to FIG. 3(b).
  • the approach angle ⁇ is adjusted by adjusting the position of the first transport roller R6 relative to the lamination roller R5 in the horizontal direction.
  • the approach angle ⁇ is at its smallest, 0°, and when the first transport roller R6 is located at the leftmost position shown by the dashed line, the approach angle ⁇ is at its largest value.
  • Fig. 11 is a diagram showing an example of the results of measuring the curl value in the TD direction and the curl value in the MD direction of the laminate F3 (second intermediate M2) produced in the inspection process ST4. Specifically, Fig. 11 shows the results of measuring the curl value of the laminate F3 (second intermediate M2) having the same configuration as the example shown in Fig. 9. The results shown in Fig. 11 were obtained when the approach angle ⁇ of the second optical film F2 to the lamination roller R1 was 43°. As shown in Figure 11, similar to the results shown in Figures 5 and 9, the curl value in the MD direction of the laminate F3 after lamination is approximately constant, while the curl value in the TD direction changes, depending on the approach angle ⁇ of the first film F1 to the lamination roller R.
  • the TD curl value of the laminate F3 after lamination can be controlled within a predetermined range, and the TD curl value of the finally manufactured optical laminate 100 can be suppressed to a level that does not cause problems in use.
  • data such as that shown in Fig.
  • the approach angle ⁇ of the first optical film F1 in contact with the first roller R5a to the lamination roller R5 is adjusted so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, and after the adjustment, the TD curl value of the laminate F3 after lamination can be controlled within a predetermined range.
  • a long strip-shaped surface protection film 5 is bonded to the long strip-shaped second intermediate M2. Specifically, the long strip-shaped surface protection film 5 is bonded to the surface of the polarizing plate 10 constituting the second intermediate M2 opposite to the surface to which the release liner 4 is bonded. In this way, a long strip-shaped optical laminate 100 is manufactured.
  • FIG. 12 is a side view (as viewed from a horizontal direction (TD direction) perpendicular to the conveying direction (MD direction) of each film) showing a schematic configuration example of an apparatus that performs the surface protective film bonding process ST5.
  • FIG. 12(a) shows a first example
  • FIG. 12(b) shows a second example.
  • the arrows shown in FIG. 12 indicate the conveying direction of each film.
  • one of the films bonded by the bonding roller is the first optical film F1
  • the other film is the second optical film F2.
  • the first optical film F1 is the second intermediate M2
  • the second optical film F2 is the surface protective film 5.
  • the first optical film F1 and the second optical film F2 are bonded together by the bonding roller R9 via the adhesive layer of the surface protective film 5, to produce a laminate F3 of the first optical film F1 and the second optical film F2.
  • the laminate F3 is the optical laminate 100.
  • a first transport roller R10 that contacts the first optical film F1 is disposed on the entry side of the lamination roller R9 (upstream of the transport direction of the first optical film F1 with respect to the lamination roller R9, and to the left of the lamination roller R9 in the example shown in Fig. 12), and the first optical film F1 is transported to the lamination roller R9 by the first transport roller R10.
  • a second transport roller R11 that contacts the second optical film F2 is disposed on the entry side of the lamination roller R9 (upstream of the transport direction of the second optical film F2 with respect to the lamination roller R9, and to the left of the lamination roller R9 in the example shown in Fig.
  • the position of the first conveying roller R10 relative to the lamination roller R9 (in the present embodiment, the position in the vertical direction) can be adjusted.
  • the first conveying roller R10 can move from the top position shown by the solid line, through the position shown by the dashed line, to the bottom position shown by the dashed line.
  • a configuration can be adopted in which the rotation shaft of the first conveying roller R10 is attached to a single-axis actuator via a bearing, and the position of the first conveying roller R10 can be adjusted by driving this single-axis actuator.
  • the second conveying roller R11 is fixed at a predetermined position.
  • the position of the second conveying roller R11 relative to the laminating roller R9 in the present embodiment, the position in the vertical direction
  • the second conveying roller R11 can move from the bottom position shown by the solid line, through the position shown by the dashed line, to the top position shown by the dashed line.
  • a configuration can be adopted in which the rotation shaft of the second conveying roller R11 is attached to a single-axis actuator via a bearing, and the position of the second conveying roller R11 can be adjusted by driving this single-axis actuator.
  • the first conveying roller R10 is fixed at a predetermined position.
  • the lamination roller R9 is composed of a first roller R9a and a second roller R9b arranged opposite the first roller R9a (opposing in the vertical direction in the example shown in Figure 12).
  • the first roller R9a in the first and second examples is a roller that comes into contact with the first optical film F1 and transports the first optical film F1 between the first roller R9a and the second roller R9b.
  • the first roller R9a is a resin roller whose surface is made of resin (silicone rubber in this embodiment).
  • the second roller R9b in the first and second examples is a roller that comes into contact with the second optical film F2 and transports the second optical film F2 between the first roller R9a and the second roller R9b.
  • the second roller R9b is also a resin roller whose surface is made of resin (silicone rubber in this embodiment).
  • the first optical film F1 and the second optical film F2 enter between the first roller R9a and the second roller R9b, whereby the first optical film F1 and the second optical film F2 are bonded together to produce a laminate F3 of the first optical film F1 and the second optical film F2.
  • the laminate F3 is transported by the transport roller R12 and taken up by a take-up roller (not shown).
  • the approach angle ⁇ of the first optical film F1 to the lamination roller R9 is adjusted so that the curl value in the TD direction of the laminate F3 is within a predetermined range.
  • the meaning of the approach angle ⁇ is the same as that described with reference to FIG. 3(b).
  • the approach angle ⁇ is adjusted by adjusting the position of the first conveying roller R10 relative to the lamination roller R9 in the vertical direction. When the first conveying roller R10 is located at the top position shown by the solid line in FIG.
  • the approach angle ⁇ is the smallest, 0°, and when the first conveying roller R10 is located at the bottom position shown by the dashed line, the approach angle ⁇ is the largest.
  • the approach angle ⁇ of the second optical film F2 to the lamination roller R9 is adjusted so that the curl value in the TD direction of the laminate F3 falls within a predetermined range.
  • the meaning of the approach angle ⁇ is the same as that described with reference to FIG. 3(b).
  • the approach angle ⁇ is adjusted by adjusting the position of the second conveying roller R11 relative to the lamination roller R9 in the vertical direction.
  • the approach angle ⁇ is the smallest, 0°, and when the second conveying roller R11 is located at the topmost position shown by the dashed line, the approach angle ⁇ is the largest.
  • FIG. 13 is a diagram showing an example of the result of measuring the curl value in the TD direction of the laminate F3 (optical laminate 100) manufactured in the surface protective film bonding process ST5.
  • the data indicated by the symbol ⁇ is the curl value in the TD direction obtained in the first example shown in FIG. 12(a)
  • the data indicated by the symbol ⁇ is the curl value in the TD direction obtained in the second example shown in FIG. 12(b).
  • FIG. 13 is a diagram showing an example of the result of measuring the curl value in the TD direction of the laminate F3 (optical laminate 100) manufactured in the surface protective film bonding process ST5.
  • the data indicated by the symbol ⁇ is the curl value in the TD direction obtained in the first example shown in FIG. 12(a)
  • the data indicated by the symbol ⁇ is the curl value in the TD direction obtained in the second example shown in FIG. 12(b).
  • FIG. 13 shows the result of measuring the curl value in the TD direction of the laminate F3 (optical laminate) in which a surface protective film 5 (substrate: polyethylene terephthalate having a thickness of 38 ⁇ m, adhesive layer: acrylic adhesive having a thickness of 10 ⁇ m) having a total thickness of 48 ⁇ m is attached to the second intermediate M2 having the same configuration as the example shown in FIG. 9.
  • the data indicated by the symbol ⁇ in FIG. 13 was obtained when the approach angle ⁇ of the second optical film F2 to the bonding roller R9 is 30°.
  • the data indicated by the symbol ⁇ in FIG. 13 was obtained when the approach angle ⁇ of the first optical film F1 to the laminating roller R9 was 30°.
  • the curl value in the TD direction of the laminate F3 after lamination changes depending on the approach angle ⁇ of the first film F1 to the lamination roller R9, similarly to the results shown in Fig. 5 etc.
  • the curl value in the TD direction of the laminate F3 after lamination changes depending on the approach angle ⁇ of the second film F2 to the lamination roller R9.
  • the TD curl value of the laminate F3 after lamination i.e., the optical laminate 100 finally manufactured
  • the TD curl value of the optical laminate 100 can be controlled within a predetermined range, and the TD curl value of the optical laminate 100 can be suppressed to a level that does not cause problems in use.
  • the TD curl value of the laminate F3 after lamination i.e., the optical laminate 100 finally manufactured
  • the TD curl value of the optical laminate 100 can be controlled within a predetermined range, and the TD curl value of the optical laminate 100 can be suppressed to a level that does not cause problems in use.
  • the approach angle ⁇ of the first optical film F1 in contact with the first roller R9a to the lamination roller R9 is adjusted so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, and after the adjustment, the TD curl value of the laminate F3 after lamination, i.e., the optical laminate 100 finally manufactured, can be controlled within a predetermined range.
  • the second example data as shown in Fig.
  • the approach angle ⁇ of the second optical film F2 in contact with the second roller R9b to the lamination roller R9 is adjusted so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, and after the adjustment, the TD curl value of the laminate F3 after lamination, i.e., the optical laminate 100 finally manufactured, can be controlled within a predetermined range.
  • FIG. 14 is a side view (as viewed from a horizontal direction (TD direction) perpendicular to the conveying direction (MD direction) of each film) showing another schematic configuration example of an apparatus that performs the surface protective film bonding process ST5 and a schematic configuration of an apparatus according to a reference example.
  • FIG. 14(a) shows a third example
  • FIG. 14(b) shows a reference example.
  • the arrows shown in FIG. 14 indicate the conveying direction of each film.
  • the third example shown in FIG. 14(a) has a configuration similar to that of the first example shown in FIG. 12(a), except that the second roller R9b is a metal roller whose surface is made of metal (iron in this embodiment).
  • the reference example shown in FIG. 14(b) has a configuration similar to that of the second example shown in FIG. 12(b), except that the second roller R9b is a metal roller whose surface is made of metal (iron in this embodiment).
  • FIG. 15 is a diagram showing an example of the results of measuring the curl value in the TD direction of the laminate F3 (optical laminate 100) manufactured in the surface protective film bonding step ST5.
  • the data indicated by the symbol ⁇ is the curl value in the TD direction obtained in the third example shown in FIG. 14(a), and the data indicated by the symbol ⁇ is the curl value in the TD direction obtained in the reference example shown in FIG. 14(b).
  • the data indicated by the symbol ⁇ in FIG. 15 was obtained when the approach angle ⁇ of the second optical film F2 to the bonding roller R9 was 30°.
  • the data indicated by the symbol ⁇ in FIG. 15 was obtained when the approach angle ⁇ of the first optical film F1 to the bonding roller R9 was 30°.
  • the curl value in the TD direction of the laminate F3 after lamination changes depending on the approach angle ⁇ of the first film F1 to the lamination roller R9, similar to the results shown in Fig. 5 etc.
  • the curl value in the TD direction of the laminate F3 after lamination is approximately constant depending on the approach angle ⁇ of the second film F2 to the lamination roller R9.
  • the TD curl value of the laminate F3 after lamination i.e., the optical laminate 100 finally manufactured
  • the TD curl value of the optical laminate 100 can be controlled within a predetermined range, and the TD curl value of the optical laminate 100 can be suppressed to a level that does not cause problems in use.
  • the TD curl value of the laminate F3 after lamination i.e., the optical laminate 100 finally manufactured, can be controlled within a predetermined range.
  • the TD curl value of the laminate F3 after lamination is approximately constant, so the TD curl value of the laminate F3 after lamination, i.e., the optical laminate 100 that is finally manufactured, cannot be controlled within a specified range, and there is a risk that the TD curl value of the optical laminate 100 cannot be suppressed to a level that does not cause problems in use.
  • the present invention is applied to three steps, namely, the release liner laminating step ST3, the inspection step ST4, and the surface protective film laminating step ST5, that is, the case where the approach angle of the optical film contacting the resin roller constituting the laminating roller to the laminating roller is adjusted has been described as an example, but the present invention is not limited thereto.
  • the present invention may be applied to only one or two of the steps ST3 to ST5, or may be applied to other steps in which films are laminated.
  • the polarizing plate 10 is a laminate of the polarizing film 1 and the retardation film 2, but the present invention is not limited to this. It is also possible to adopt an embodiment in which the polarizing plate 10 is a laminate of the polarizing film 1, the retardation film 2, and other components, an embodiment in which the retardation film 2 is not present and the polarizing plate 10 is a laminate of the polarizing film 1 and other components, or an embodiment in which only the polarizing film 1 is present in the polarizing plate 10.
  • Polarizing film 3 Pressure-sensitive adhesive layer 4: Release liner 5: Surface protective film 10: Polarizing plate 100: Optical laminate F1: First optical film F2: Second optical film M1: First intermediate M2: Second intermediate R1, R5, R9: Lamination rollers R1a, R5a, R9a: First roller R1b, R5b, R9b: Second roller R2, R6, R10: First conveyor roller R3, R7, R11: Second conveyor roller ⁇ , ⁇ : Approach angle

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  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
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  • Textile Engineering (AREA)
  • Polarising Elements (AREA)
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Abstract

[Problem] To provide a method for producing an optical laminate, the method being capable of suppressing curling. [Solution] A method for producing an optical laminate 100 according to the present invention comprises a step in which a first optical film F1 comprising a polarizing plate 10 and a second optical film F2 are bonded to each other, with an adhesive layer 3 being interposed therebetween, by a bonding roller R1. The bonding roller is composed of a first roller R1a which comes into contact with the first optical film, and a second roller R1b which comes into contact with the second optical film. The surface of the first roller is formed of a resin, while the surface of the second roller is formed of a metal or a resin. The approach angle α of the first optical film with respect to the bonding roller is adjusted so that the curling value in the TD direction of a laminate F3 of the first optical film and the second optical film is within a predetermined range, or alternatively, in cases where the surface of the second roller is formed of a resin, the approach angle β of the second optical film with respect to the bonding roller is adjusted so that the curling value in the TD direction of the laminate F3 is within a predetermined range.

Description

光学積層体の製造方法Method for producing optical laminate
　本発明は、少なくとも偏光板を備えた光学積層体の製造方法に関する。特に、本発明は、カールを抑制可能な光学積層体の製造方法に関する。 The present invention relates to a method for manufacturing an optical laminate having at least a polarizing plate. In particular, the present invention relates to a method for manufacturing an optical laminate capable of suppressing curling.
　従来、液晶表示装置や有機ＥＬ表示装置等の構成材料として、偏光板が使用されている。偏光板は、偏光フィルムの他、用途に応じて位相差フィルム等を備える。偏光フィルムは、例えば、ヨウ素などの二色性物質で染色した偏光子とこの偏光子を保護する保護フィルムとから構成されている。長尺帯状の偏光フィルムは、長尺帯状の偏光子の少なくとも片面に長尺帯状の保護フィルムを貼り合わせて製造される。製造された長尺帯状の偏光フィルムの片面には、長尺帯状の位相差フィルム等が貼り合わせられて、長尺帯状の偏光板が製造される。製造された長尺帯状の偏光板の片面には、長尺帯状のはく離ライナーが貼り合わせられ、他方の面には、長尺帯状の表面保護フィルムが貼り合わせられて、長尺帯状の光学積層体が製造される。これら長尺帯状の各フィルムの貼り合わせは、通常、ロールツーロール方式で行われる。製造された長尺帯状の光学積層体は、用途に応じたサイズや形状に切断され、液晶表示装置等に用いられる。なお、液晶表示装置等に用いられる際には、はく離ライナーは、はく離されて、光学積層体の残りの構成要素が液晶表示装置等に貼り付けられる。 Conventionally, polarizing plates have been used as a component material for liquid crystal display devices, organic EL display devices, and the like. In addition to a polarizing film, a polarizing plate includes a retardation film and the like depending on the application. A polarizing film is composed of, for example, a polarizer dyed with a dichroic substance such as iodine and a protective film that protects the polarizer. A long strip-shaped polarizing film is manufactured by laminating a long strip-shaped protective film to at least one side of a long strip-shaped polarizer. A long strip-shaped retardation film and the like are laminated to one side of the manufactured long strip-shaped polarizing film to manufacture a long strip-shaped polarizing plate. A long strip-shaped release liner is laminated to one side of the manufactured long strip-shaped polarizing plate, and a long strip-shaped surface protective film is laminated to the other side to manufacture a long strip-shaped optical laminate. The lamination of each of these long strip-shaped films is usually performed by a roll-to-roll method. The manufactured long strip-shaped optical laminate is cut to a size and shape depending on the application and used in a liquid crystal display device or the like. When used in a liquid crystal display device, the release liner is peeled off and the remaining components of the optical laminate are attached to the liquid crystal display device, etc.
　従来、上記の光学積層体は、一般に、偏光フィルム製造工程、位相差フィルム貼合工程、はく離ライナー貼合工程、検査工程及び表面保護フィルム貼合工程を有する製造方法によって製造される。 Conventionally, the above optical laminates are generally manufactured by a manufacturing method that includes a polarizing film manufacturing process, a retardation film lamination process, a release liner lamination process, an inspection process, and a surface protection film lamination process.
　偏光フィルム製造工程では、長尺帯状の樹脂フィルムを原反フィルムとして、この原反フィルムを長手方向に搬送しながら各種の処理浴に浸漬させて、染色処理や延伸処理等の各種の処理を施すことによって、長尺帯状の偏光子を製造する。そして、長尺帯状の偏光子の少なくとも片面に長尺帯状の保護フィルムを貼り合わせることで、長尺帯状の偏光フィルムを製造する。 In the polarizing film manufacturing process, a long strip of resin film is used as the raw film, which is transported in the longitudinal direction while being immersed in various treatment baths and subjected to various treatments such as dyeing and stretching to produce a long strip of polarizer. A long strip of protective film is then attached to at least one side of the long strip of polarizer to produce a long strip of polarizing film.
　位相差フィルム貼合工程では、長尺帯状の偏光フィルムの片面に長尺帯状の位相差フィルム（１／２波長板や１／４波長板など）を貼り合わせることで、長尺帯状の偏光板を製造する。 In the phase difference film lamination process, a long strip of phase difference film (such as a half-wave plate or a quarter-wave plate) is laminated to one side of a long strip of polarizing film to produce a long strip of polarizing plate.
　はく離ライナー貼合工程では、長尺帯状のはく離ライナーを長手方向に搬送しながら粘着剤を塗布し、この塗布した粘着剤をオーブン等で加熱して乾燥させることで硬化させ、粘着剤層を形成する。そして、この長尺帯状のはく離ライナー（粘着剤層付きはく離ライナー）の粘着剤層側を長尺帯状の偏光板の片面に貼り合わせることで、偏光板と粘着剤層とはく離ライナーとが積層された長尺帯状の中間体を製造する。はく離ライナーだけでなく、偏光板にも粘着剤層を形成し、はく離ライナーの粘着剤層側と、偏光板の粘着剤層側とを貼り合わせることで、長尺帯状の中間体を製造する場合もある。 In the release liner lamination process, adhesive is applied to a long strip of release liner while it is being transported in the longitudinal direction, and the applied adhesive is heated and dried in an oven or the like to harden it and form an adhesive layer. The adhesive layer side of this long strip of release liner (release liner with adhesive layer) is then laminated to one side of a long strip of polarizing plate to produce a long strip of intermediate product in which a polarizing plate, adhesive layer, and release liner are laminated. In some cases, an adhesive layer is formed not only on the release liner but also on the polarizing plate, and the adhesive layer side of the release liner is laminated to the adhesive layer side of the polarizing plate to produce a long strip of intermediate product.
　検査工程では、はく離ライナーと偏光板との間に介在する粘着剤層を偏光板側に残したまま、はく離ライナーのみをはく離して、偏光板を検査する。偏光板の検査方法としては、透過検査、クロスニコル検査、反射検査などが挙げられる。検査工程では、偏光板を検査した後、はく離したはく離ライナーを再び偏光板に貼り合わせる（はく離したはく離ライナーとは異なる新しいはく離ライナーを偏光板に貼り合わせることを含む）ことで、元の中間体の状態に戻す。 In the inspection process, the release liner is peeled off while leaving the adhesive layer between the release liner and the polarizing plate on the polarizing plate side, and the polarizing plate is inspected. Inspection methods for polarizing plates include transmission inspection, crossed Nicol inspection, and reflection inspection. In the inspection process, after inspecting the polarizing plate, the peeled release liner is reattached to the polarizing plate (including attaching a new release liner different from the peeled one to the polarizing plate) to return it to its original intermediate state.
　表面保護フィルム貼合工程では、長尺帯状の偏光板のはく離ライナーが貼り合わせられた側とは反対側の面に長尺帯状の表面保護フィルムが貼り合わせられる。 In the surface protection film lamination process, a long strip of surface protection film is laminated to the side of the long strip of polarizing plate opposite the side to which the release liner is laminated.
　しかしながら、以上のようにして製造される光学積層体には、製品サイズに切断後の光学積層体に、使用上問題となるカール（端部の反り）が発生する場合がある。
　例えば、特許文献１には、偏光フィルムのカールを抑制する方法として、偏光子を保護する保護フィルムの材質を特定のものにすることが提案されているが、保護フィルムの材質が限定されるため、汎用的ではない。従来用いられている光学積層体の構成要素の材質を特に変えることなく、カールを抑制可能な方法が望まれている。 However, the optical laminate produced as described above may suffer from curling (warping of the edges) that is problematic in use after being cut into a product size.
For example, Patent Document 1 proposes using a specific material for a protective film that protects a polarizer as a method for suppressing curling of a polarizing film, but the material of the protective film is limited and is not versatile. A method capable of suppressing curling without particularly changing the materials of the components of a conventionally used optical laminate is desired.
特開２００７－２５６５６８号公報JP 2007-256568 A
　本発明は、上記従来技術の問題点を解決するためになされたものであり、カールを抑制可能な光学積層体の製造方法を提供することを課題とする。 The present invention was made to solve the problems of the conventional technology described above, and aims to provide a method for manufacturing an optical laminate that can suppress curling.
　前記課題を解決するため、本発明者らは鋭意検討した結果、従来の光学積層体の製造方法における、各種フィルムの貼合工程（例えば、はく離ライナー貼合工程、検査工程におけるはく離ライナーの再貼合工程、表面保護フィルム貼合工程）における貼合ローラの表面の材質や、フィルムの貼合ローラへの進入角度が、貼り合わせ後の積層体のカール値（カールの程度を表す指標）に影響を及ぼすことを見出した。
　具体的には、貼合ローラを構成する少なくとも一方のローラの表面がゴム等の樹脂から形成されている場合に、このローラ（以下、適宜「樹脂ローラ」という）に接触するフィルムの貼合ローラへの進入角度に応じて、貼り合わせ後の積層体の長手方向（搬送方向、ＭＤ方向）に直交する方向（ＴＤ方向）のカール値が変化することを見出した。
　したがって、貼り合わせ後の積層体のＴＤ方向のカール値が所定の範囲内となるように、樹脂ローラに接触するフィルムの貼合ローラへの進入角度を調整すれば、貼り合わせ後の積層体のＴＤ方向のカール値を所定の範囲内に制御でき、ひいては、最終的に製造される光学積層体のＴＤ方向のカール値を使用上問題とならない程度に抑制できることが分かった。
　本発明は、本発明者らの上記知見に基づき完成したものである。 In order to solve the above problems, the present inventors conducted extensive research and found that in conventional methods for producing optical laminates, the surface material of the lamination roller and the approach angle of the film to the lamination roller in the lamination steps of various films (e.g., a release liner lamination step, a release liner re-lamination step in an inspection step, and a surface protection film lamination step) affect the curl value (an index representing the degree of curl) of the laminate after lamination.
Specifically, they found that when the surface of at least one of the rollers constituting the lamination roller is formed from a resin such as rubber, the curl value in the direction (TD direction) perpendicular to the longitudinal direction (conveyance direction, MD direction) of the laminate after lamination changes depending on the angle at which the film contacting this roller (hereinafter referred to as the "resin roller" as appropriate) enters the lamination roller.
Therefore, it was found that by adjusting the angle of entry of the film contacting the resin roller into the lamination roller so that the TD curl value of the laminate after lamination is within a specified range, the TD curl value of the laminate after lamination can be controlled within a specified range, and ultimately the TD curl value of the optical laminate finally manufactured can be suppressed to a level that does not cause problems in use.
The present invention has been completed based on the above findings of the present inventors.
　すなわち、前記課題を解決するため、本発明は、長手方向に搬送される偏光板を含む長尺帯状の第１光学フィルムと、長手方向に搬送される長尺帯状の第２光学フィルムとを、粘着剤層を介して、貼合ローラによって貼り合わせる工程を有する光学積層体の製造方法であって、前記貼合ローラは、前記第１光学フィルムに接触する第１ローラと、前記第１ローラに対向して配置され、前記第２光学フィルムに接触する第２ローラと、から構成され、前記第１光学フィルム及び前記第２光学フィルムが前記第１ローラと前記第２ローラとの間に進入することで、前記第１光学フィルムと前記第２光学フィルムとが貼り合わせられ、前記第１ローラ及び前記第２ローラのうち、少なくとも何れか一方のローラの表面は樹脂から形成されており、前記第１ローラの表面が樹脂から形成されている場合に、前記第１光学フィルムと前記第２光学フィルムとの積層体の長手方向に直交する方向のカール値が所定の範囲内となるように、前記第１光学フィルムの前記貼合ローラへの進入角度を調整するか、又は、前記第２ローラの表面が樹脂から形成されている場合に、前記第１光学フィルムと前記第２光学フィルムとの積層体の長手方向に直交する方向のカール値が所定の範囲内となるように、前記第２光学フィルムの前記貼合ローラへの進入角度を調整する、光学積層体の製造方法を提供する。 That is, in order to solve the above problem, the present invention provides a method for manufacturing an optical laminate, which includes a step of bonding a long strip-shaped first optical film including a polarizing plate transported in a longitudinal direction and a long strip-shaped second optical film transported in a longitudinal direction, via an adhesive layer, by a bonding roller, the bonding roller being composed of a first roller that contacts the first optical film, and a second roller that is disposed opposite the first roller and contacts the second optical film, the first optical film and the second optical film are bonded together by entering between the first roller and the second roller, and the first roller The surface of at least one of the lamination roller and the second roller is made of resin, and when the surface of the first roller is made of resin, the angle of entry of the first optical film into the lamination roller is adjusted so that the curl value in the direction perpendicular to the longitudinal direction of the laminate of the first optical film and the second optical film falls within a predetermined range, or when the surface of the second roller is made of resin, the angle of entry of the second optical film into the lamination roller is adjusted so that the curl value in the direction perpendicular to the longitudinal direction of the laminate of the first optical film and the second optical film falls within a predetermined range.
　本発明において、「第１光学フィルムの貼合ローラへの進入角度」とは、貼合ローラを構成する第１ローラの回転中心及び第２ローラの回転中心に直交する断面において、第１ローラの回転中心及び第２ローラの回転中心を通る直線に直交し、貼合ローラの出側に向いたベクトルと、貼合ローラに接触するまでの第１光学フィルムの進行方向を示すベクトルとの成す角度を意味する。
　同様に、「第２光学フィルムの貼合ローラへの進入角度」とは、貼合ローラを構成する第１ローラの回転中心及び第２ローラの回転中心に直交する断面において、第１ローラの回転中心及び第２ローラの回転中心を通る直線に直交し、貼合ローラの出側に向いたベクトルと、貼合ローラに接触するまでの第２光学フィルムの進行方向を示すベクトルとの成す角度を意味する。 In the present invention, the "approach angle of the first optical film to the laminating roller" means an angle formed by a vector perpendicular to a line passing through the rotation centers of the first roller and the second roller that constitute the laminating roller, the vector perpendicular to the rotation center of the first roller and the rotation center of the second roller, and pointing toward the exit side of the laminating roller, and the vector that indicates the traveling direction of the first optical film until it comes into contact with the laminating roller, in a cross section perpendicular to the rotation center of the first roller and the rotation center of the second roller that constitute the laminating roller.
Similarly, the "angle of entry of the second optical film into the laminating roller" means the angle formed by a vector perpendicular to a line passing through the centers of rotation of the first roller and the second roller that constitute the laminating roller, the vector perpendicular to the line passing through the centers of rotation of the first roller and the second roller and pointing toward the exit side of the laminating roller, and the vector indicating the direction of travel of the second optical film until it comes into contact with the laminating roller, in a cross section perpendicular to the centers of rotation of the first roller and the second roller that constitute the laminating roller.
　本発明によれば、第１ローラが樹脂ローラである場合には、第１ローラに接触する第１光学フィルムの貼合ローラへの進入角度を調整することで、本発明者らが知見したように、第１光学フィルムと第２光学フィルムとの積層体のＴＤ方向のカール値を所定の範囲内に制御することができ、ひいては、光学積層体のＴＤ方向のカール値を使用上問題とならない程度に抑制可能である。
　また、第２ローラが樹脂ローラである場合には、第２ローラに接触する第２光学フィルムの貼合ローラへの進入角度を調整することでも、第１光学フィルムと第２光学フィルムとの積層体のＴＤ方向のカール値を所定の範囲内に制御することができ、ひいては、光学積層体のＴＤ方向のカール値を使用上問題とならない程度に抑制可能である。 According to the present invention, when the first roller is a resin roller, by adjusting the angle of entry of the first optical film, which contacts the first roller, into the lamination roller, the inventors have discovered that the curl value in the TD direction of the laminate of the first optical film and the second optical film can be controlled within a predetermined range, and ultimately the curl value in the TD direction of the optical laminate can be suppressed to a level that does not cause problems in use.
In addition, when the second roller is a resin roller, the curl value in the TD direction of the laminate of the first optical film and the second optical film can be controlled within a predetermined range by adjusting the angle of entry of the second optical film, which contacts the second roller, into the lamination roller, and ultimately, the curl value in the TD direction of the optical laminate can be suppressed to a level that does not cause problems in use.
　本発明において、前記第１ローラの表面が樹脂から形成されていることが好ましい。
　上記の好ましい方法によれば、偏光板を含む第１光学フィルムに接触する第１ローラの表面が樹脂から形成された樹脂ローラであるため、偏光板に傷や打痕等の外観不良が生じることを抑制可能である。 In the present invention, it is preferable that the surface of the first roller is made of resin.
According to the above-mentioned preferred method, since the surface of the first roller that contacts the first optical film including the polarizing plate is a resin roller formed from resin, it is possible to suppress the occurrence of appearance defects such as scratches and dents on the polarizing plate.
　本発明において、好ましくは、前記第１ローラの表面が樹脂から形成されている場合に、前記貼合ローラの入側に前記第１光学フィルムに接触する第１搬送ローラを配置し、前記第１搬送ローラの前記貼合ローラに対する位置を調整することで、前記第１光学フィルムの前記貼合ローラへの進入角度を調整するか、又は、前記第２ローラの表面が樹脂から形成されている場合に、前記貼合ローラの入側に前記第２光学フィルムに接触する第２搬送ローラを配置し、前記第２搬送ローラの前記貼合ローラに対する位置を調整することで、前記第２光学フィルムの前記貼合ローラへの進入角度を調整する。 In the present invention, preferably, when the surface of the first roller is made of resin, a first transport roller that comes into contact with the first optical film is disposed on the entry side of the lamination roller, and the position of the first transport roller relative to the lamination roller is adjusted to adjust the angle of entry of the first optical film into the lamination roller; or, when the surface of the second roller is made of resin, a second transport roller that comes into contact with the second optical film is disposed on the entry side of the lamination roller, and the position of the second transport roller relative to the lamination roller is adjusted to adjust the angle of entry of the second optical film into the lamination roller.
　上記の好ましい方法において、「貼合ローラの入側」とは、貼合ローラに対して、第１光学フィルム又は第２光学フィルムの搬送方向上流側を意味する。
　上記の好ましい構成によれば、第１搬送ローラ又は第２搬送ローラの位置を調整することで、第１光学フィルム又は第２光学フィルムの貼合ローラへの進入角度を容易に調整可能である。 In the above-mentioned preferred method, the term "entrance side of the lamination roller" means the upstream side of the lamination roller in the transport direction of the first optical film or the second optical film.
According to the above-described preferred configuration, the angle at which the first optical film or the second optical film approaches the lamination roller can be easily adjusted by adjusting the position of the first transport roller or the second transport roller.
　本発明において、第２光学フィルムがはく離ライナーであり、前記第２ローラの表面が金属から形成されている場合を例示できる。
　この場合、第２ローラが金属ローラ（以下、表面が鉄等の金属から形成されているローラを適宜「金属ローラ」という）であるため、第１光学フィルムと第２光学フィルムとの積層体のＴＤ方向のカール値が所定の範囲内となるように、第１光学フィルムの貼合ローラへの進入角度が調整されることになる。 In the present invention, the second optical film may be a release liner, and the surface of the second roller may be made of metal.
In this case, since the second roller is a metal roller (hereinafter, a roller whose surface is formed from a metal such as iron will be referred to as a "metal roller" as appropriate), the angle of entry of the first optical film into the lamination roller is adjusted so that the curl value in the TD direction of the laminate of the first optical film and the second optical film is within a predetermined range.
　本発明において、前記第２光学フィルムが表面保護フィルムである場合を例示できる。 In the present invention, the second optical film may be a surface protection film.
　本発明において、好ましくは、前記第１ローラの表面が樹脂から形成されている場合に、前記第１光学フィルムの前記貼合ローラへの進入角度を７５°以下（より好ましくは、６０°以下）に調整するか、又は、前記第２ローラの表面が樹脂から形成されている場合に、前記第２光学フィルムの前記貼合ローラへの進入角度を７５°以下（より好ましくは、６０°以下）に調整する。 In the present invention, preferably, when the surface of the first roller is made of resin, the angle of entry of the first optical film into the lamination roller is adjusted to 75° or less (more preferably, 60° or less), or when the surface of the second roller is made of resin, the angle of entry of the second optical film into the lamination roller is adjusted to 75° or less (more preferably, 60° or less).
　本発明において、前記第１ローラの表面が樹脂から形成されている場合、前記第１ローラの表面は、例えば、シリコンゴム等のゴムから形成されるのが好ましい。また、前記第２ローラの表面が樹脂から形成されている場合、例えば、シリコンゴム等のゴムから形成されるのが好ましい。 In the present invention, when the surface of the first roller is made of resin, it is preferable that the surface of the first roller is made of rubber, such as silicone rubber. Also, when the surface of the second roller is made of resin, it is preferable that the surface of the second roller is made of rubber, such as silicone rubber.
　以上を纏めると、本発明は、以下の事項に関する。
　［１］長手方向に搬送される偏光板を含む長尺帯状の第１光学フィルムと、長手方向に搬送される長尺帯状の第２光学フィルムとを、粘着剤層を介して、貼合ローラによって貼り合わせる工程を有する光学積層体の製造方法であって、前記貼合ローラは、前記第１光学フィルムに接触する第１ローラと、前記第１ローラに対向して配置され、前記第２光学フィルムに接触する第２ローラと、から構成され、前記第１光学フィルム及び前記第２光学フィルムが前記第１ローラと前記第２ローラとの間に進入することで、前記第１光学フィルムと前記第２光学フィルムとが貼り合わせられ、前記第１ローラ及び前記第２ローラのうち、少なくとも何れか一方のローラの表面は樹脂から形成されており、前記第１ローラの表面が樹脂から形成されている場合に、前記第１光学フィルムと前記第２光学フィルムとの積層体の長手方向に直交する方向のカール値が所定の範囲内となるように、前記第１光学フィルムの前記貼合ローラへの進入角度を調整するか、又は、前記第２ローラの表面が樹脂から形成されている場合に、前記第１光学フィルムと前記第２光学フィルムとの積層体の長手方向に直交する方向のカール値が所定の範囲内となるように、前記第２光学フィルムの前記貼合ローラへの進入角度を調整する、光学積層体の製造方法。
　［２］前記第１ローラの表面が樹脂から形成されている、［１］に記載の光学積層体の製造方法。
　［３］前記第１ローラの表面が樹脂から形成されている場合に、前記貼合ローラの入側に前記第１光学フィルムに接触する第１搬送ローラを配置し、前記第１搬送ローラの前記貼合ローラに対する位置を調整することで、前記第１光学フィルムの前記貼合ローラへの進入角度を調整するか、又は、前記第２ローラの表面が樹脂から形成されている場合に、前記貼合ローラの入側に前記第２光学フィルムに接触する第２搬送ローラを配置し、前記第２搬送ローラの前記貼合ローラに対する位置を調整することで、前記第２光学フィルムの前記貼合ローラへの進入角度を調整する、［１］又は［２］に記載の光学積層体の製造方法。
　［４］前記第２光学フィルムがはく離ライナーであり、前記第２ローラの表面が金属から形成されている、［１］から［３］の何れかに記載の光学積層体の製造方法。
　［５］前記第２光学フィルムが表面保護フィルムである、［１］から［３］の何れかに記載の光学積層体の製造方法。
　［６］前記第１ローラの表面が樹脂から形成されている場合に、前記第１光学フィルムの前記貼合ローラへの進入角度を７５°以下に調整するか、又は、前記第２ローラの表面が樹脂から形成されている場合に、前記第２光学フィルムの前記貼合ローラへの進入角度を７５°以下に調整する、［１］から［５］の何れかに記載の光学積層体の製造方法。
　［７］前記第１ローラの表面が樹脂から形成されている場合には、前記第１ローラの表面がゴムから形成され、前記第２ローラの表面が樹脂から形成されている場合には、前記第２ローラの表面がゴムから形成されている、［１］から［６］の何れかに記載の光学積層体の製造方法。 In summary, the present invention relates to the following items.
[1] A method for producing an optical laminate, comprising a step of laminating a long strip-shaped first optical film including a polarizing plate transported in a longitudinal direction and a long strip-shaped second optical film transported in the longitudinal direction, via an adhesive layer, by a laminating roller, the laminating roller being composed of a first roller that contacts the first optical film, and a second roller that is disposed opposite to the first roller and contacts the second optical film, the first optical film and the second optical film are laminated together by entering between the first roller and the second roller, and the first roller and the second roller are laminated together by the first roller and the second roller. a surface of at least one of the laminating rollers is formed from resin, and when the surface of the first roller is formed from resin, an approach angle of the first optical film to the laminating roller is adjusted so that a curl value in a direction perpendicular to the longitudinal direction of the laminate of the first optical film and the second optical film falls within a predetermined range; or, when the surface of the second roller is formed from resin, an approach angle of the second optical film to the laminating roller is adjusted so that a curl value in a direction perpendicular to the longitudinal direction of the laminate of the first optical film and the second optical film falls within a predetermined range.
[2] The method for producing an optical laminate described in [1], wherein the surface of the first roller is formed from a resin.
[3] The method for producing an optical laminate according to [1] or [2], wherein, when the surface of the first roller is formed from a resin, a first transport roller that comes into contact with the first optical film is disposed on the entry side of the lamination roller, and the position of the first transport roller with respect to the lamination roller is adjusted to adjust an entry angle of the first optical film to the lamination roller; or, when the surface of the second roller is formed from a resin, a second transport roller that comes into contact with the second optical film is disposed on the entry side of the lamination roller, and the position of the second transport roller with respect to the lamination roller is adjusted to adjust an entry angle of the second optical film to the lamination roller.
[4] The method for producing an optical laminate described in any one of [1] to [3], wherein the second optical film is a release liner and the surface of the second roller is formed from a metal.
[5] The method for producing an optical laminate described in any one of [1] to [3], wherein the second optical film is a surface protection film.
[6] The method for producing an optical laminate described in any one of [1] to [5], wherein, when the surface of the first roller is formed of resin, an approach angle of the first optical film to the lamination roller is adjusted to 75° or less, or, when the surface of the second roller is formed of resin, an approach angle of the second optical film to the lamination roller is adjusted to 75° or less.
[7] A method for producing an optical laminate described in any of [1] to [6], wherein when the surface of the first roller is formed from resin, the surface of the first roller is formed from rubber, and when the surface of the second roller is formed from resin, the surface of the second roller is formed from rubber.
　本発明によれば、従来用いられている光学積層体の構成要素の材質を特に変えることなく、カールを効果的に抑制可能である。 According to the present invention, curling can be effectively suppressed without making any particular changes to the materials of the components of conventionally used optical laminates.
本発明の一実施形態に係る製造方法によって製造される光学積層体の概略構成を模式的に示す断面図である。1 is a cross-sectional view showing a schematic configuration of an optical laminate produced by a production method according to one embodiment of the present invention. 本発明の一実施形態に係る光学積層体の製造方法の概略工程を示すフロー図である。FIG. 1 is a flow diagram showing schematic steps of a method for producing an optical laminate according to one embodiment of the present invention. 図２に示すはく離ライナー貼合工程ＳＴ３を実行する装置の概略構成例を模式的に示す図である。3 is a diagram illustrating an example of a schematic configuration of an apparatus for performing the release liner bonding step ST3 illustrated in FIG. 2. FIG. カール値の測定方法の概要を説明する説明図である。FIG. 2 is an explanatory diagram for explaining an outline of a method for measuring a curl value. 図２に示すはく離ライナー貼合工程ＳＴ３で製造された積層体Ｆ３（第２中間体Ｍ２）のＴＤ方向のカール値及びＭＤ方向のカール値を測定した結果の一例を示す図である。3 is a diagram showing an example of the results of measuring the curl value in the TD direction and the curl value in the MD direction of the laminate F3 (second intermediate M2) produced in the release liner attachment step ST3 shown in FIG. 2. 本発明者らが行ったローラたわみ量とＴＤ方向のカール値との関係を調査する試験の概要及び結果の一例を示す図である。FIG. 13 is a diagram showing an example of the outline and results of a test conducted by the present inventors to investigate the relationship between the amount of roller deflection and the curl value in the TD direction. 本発明者らが行った第１光学フィルムＦ１の表面の位置を測定する試験の概要及び結果の一例を示す図である。1 is a diagram showing an example of the outline and results of a test conducted by the present inventors to measure the position on the surface of a first optical film F1. FIG. 本発明者らが推測した、樹脂ローラである第１ローラＲ１ａに接触する第１光学フィルムＦ１の貼合ローラＲ１への進入角度αに応じて、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が変化する理由を模式的に説明する説明図である。FIG. 1 is an explanatory diagram that illustrates the reason why the inventors speculate that the TD curl value of the laminate F3 after lamination changes depending on the approach angle α of the first optical film F1, which is in contact with the first roller R1a, which is a resin roller, to the lamination roller R1. 図２に示すはく離ライナー貼合工程ＳＴ３で製造された積層体Ｆ３（第２中間体Ｍ２）のＴＤ方向のカール値及びＭＤ方向のカール値を測定した結果の他の例を示す図である。13 is a diagram showing another example of the results of measuring the curl value in the TD direction and the curl value in the MD direction of the laminate F3 (second intermediate M2) produced in the release liner attachment step ST3 shown in FIG. 2. 図２に示す検査工程ＳＴ４において、はく離ライナー４を再び偏光板１０に貼り合わせる装置の概略構成例を模式的に示す側面図である。3 is a side view showing a schematic configuration example of an apparatus for bonding release liner 4 again to polarizing plate 10 in inspection step ST4 shown in FIG. 2. FIG. 図２に示す検査工程ＳＴ４で製造された積層体Ｆ３（第２中間体Ｍ２）のＴＤ方向のカール値及びＭＤ方向のカール値を測定した結果の一例を示す図である。3 is a diagram showing an example of the results of measuring the curl value in the TD direction and the curl value in the MD direction of the laminate F3 (second intermediate M2) produced in the inspection process ST4 shown in FIG. 2. 図２に示す表面保護フィルム貼合工程ＳＴ５を実行する装置の概略構成例を模式的に示す側面図である。3 is a side view showing a schematic configuration example of an apparatus for performing the surface protective film bonding step ST5 shown in FIG. 2. 図２に示す表面保護フィルム貼合工程ＳＴ５で製造された積層体Ｆ３（光学積層体１００）のＴＤ方向のカール値を測定した結果の一例を示す図である。3 is a diagram showing an example of the results of measuring the curl value in the TD direction of the laminate F3 (optical laminate 100) produced in the surface protective film attachment step ST5 shown in FIG. 2. FIG. 図２に示す表面保護フィルム貼合工程ＳＴ５を実行する装置の他の概略構成例及び参考例に係る装置の概略構成を模式的に示す側面図である。3 is a side view showing a schematic configuration of another example of the schematic configuration of an apparatus for performing the surface protective film bonding step ST5 shown in FIG. 2 and a schematic configuration of an apparatus according to a reference example. FIG. 図２に示す表面保護フィルム貼合工程ＳＴ５で製造された積層体Ｆ３（光学積層体１００）のＴＤ方向のカール値を測定した結果の一例を示す図である。3 is a diagram showing an example of the results of measuring the curl value in the TD direction of the laminate F3 (optical laminate 100) produced in the surface protective film attachment step ST5 shown in FIG. 2. FIG.
　以下、添付図面を適宜参照しつつ、本発明の一実施形態に係る光学積層体の製造方法について説明する。なお、各図は、参考的に表したものであり、各図に表された光学積層体や装置の構成要素の寸法、縮尺及び形状は、実際のものとは異なっている場合があることに留意されたい。 Below, a method for producing an optical laminate according to one embodiment of the present invention will be described with reference to the attached drawings. Please note that each figure is for reference only, and the dimensions, scale, and shapes of the optical laminate and device components shown in each figure may differ from the actual ones.
　＜光学積層体の構成＞
　最初に、本実施形態に係る製造方法によって製造される光学積層体の構成について説明する。
　図１は、本実施形態に係る製造方法によって製造される光学積層体の概略構成を模式的に示す断面図である。
　図１に示すように、本実施形態の光学積層体１００は、偏光フィルム１と、位相差フィルム２と、粘着剤層３と、はく離ライナー４と、表面保護フィルム５と、を備える。偏光フィルム１と位相差フィルム２との積層体が偏光板１０を構成している。偏光板１０と粘着剤層３との積層体が第１中間体Ｍ１を構成している。第１中間体Ｍ１とはく離ライナー４との積層体が第２中間体Ｍ２を構成している。以下、光学積層体１００の各構成要素について説明する。 <Configuration of optical laminate>
First, the configuration of the optical laminate produced by the production method according to this embodiment will be described.
FIG. 1 is a cross-sectional view that illustrates a schematic configuration of an optical laminate produced by a production method according to this embodiment.
As shown in Fig. 1, the optical laminate 100 of this embodiment includes a polarizing film 1, a retardation film 2, a pressure-sensitive adhesive layer 3, a release liner 4, and a surface protective film 5. A laminate of the polarizing film 1 and the retardation film 2 constitutes a polarizing plate 10. A laminate of the polarizing plate 10 and the pressure-sensitive adhesive layer 3 constitutes a first intermediate M1. A laminate of the first intermediate M1 and the release liner 4 constitutes a second intermediate M2. Each component of the optical laminate 100 will be described below.
　［偏光フィルム１］
　偏光フィルム１は、偏光子１１と、この偏光子１１を保護する保護フィルム１２、１３とから構成されている。本実施形態では、偏光子１１の両面に保護フィルム１２、１３が貼り合わせられているが、これに限るものではなく、偏光子１１の少なくとも片面に保護フィルムが貼り合わせられていればよい。 [Polarizing film 1]
The polarizing film 1 is composed of a polarizer 11 and protective films 12 and 13 that protect the polarizer 11. In this embodiment, the protective films 12 and 13 are bonded to both sides of the polarizer 11, but this is not limited thereto, and it is sufficient that a protective film is bonded to at least one side of the polarizer 11.
　（偏光子１１）
　偏光子１１は、代表的には、二色性物質を含む樹脂フィルムで構成される。
　樹脂フィルムとしては、偏光子として用いることができる任意の適切な樹脂フィルムを採用することができる。樹脂フィルムは、代表的には、ポリビニルアルコール系樹脂（以下、「ＰＶＡ系樹脂」と称する）フィルムである。 (Polarizer 11)
The polarizer 11 is typically made of a resin film containing a dichroic material.
As the resin film, any appropriate resin film that can be used as a polarizer can be adopted. The resin film is typically a polyvinyl alcohol-based resin (hereinafter, referred to as a "PVA-based resin") film.
　上記ＰＶＡ系樹脂フィルムを形成するＰＶＡ系樹脂としては、任意の適切な樹脂を用いることができる。例えば、ポリビニルアルコール、エチレン－ビニルアルコール共重合体が挙げられる。ポリビニルアルコールは、ポリ酢酸ビニルをケン化することにより得られる。エチレン－ビニルアルコール共重合体は、エチレン－酢酸ビニル共重合体をケン化することにより得られる。 Any suitable resin can be used as the PVA-based resin that forms the PVA-based resin film. Examples include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol can be obtained by saponifying polyvinyl acetate. Ethylene-vinyl alcohol copolymer can be obtained by saponifying ethylene-vinyl acetate copolymer.
　ＰＶＡ系樹脂の平均重合度は、目的に応じて適切に選択することができる。平均重合度は、通常１０００～１００００であり、好ましくは１２００～４５００、さらに好ましくは１５００～４３００である。なお、平均重合度は、ＪＩＳ　Ｋ　６７２６－１９９４に準じて求めることができる。 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 1,000 to 10,000, preferably 1,200 to 4,500, and more preferably 1,500 to 4,300. The average degree of polymerization can be determined in accordance with JIS K 6726-1994.
　樹脂フィルムに含まれる二色性物質としては、例えば、ヨウ素、有機染料等が挙げられる。これらは、単独で、又は、二種以上を組み合わせて用いることができる。好ましくは、ヨウ素が用いられる。 Examples of dichroic substances contained in the resin film include iodine and organic dyes. These can be used alone or in combination of two or more. Iodine is preferably used.
　樹脂フィルムは、単層の樹脂フィルムであっても、二層以上の積層体であってもよい。 The resin film may be a single-layer resin film or a laminate of two or more layers.
　単層の樹脂フィルムから構成される偏光子の具体例としては、ＰＶＡ系樹脂フィルムにヨウ素による染色処理及び延伸処理（代表的には、一軸延伸処理）が施されたものが挙げられる。ヨウ素による染色処理は、例えば、ＰＶＡ系フィルムをヨウ素水溶液に浸漬することによって行われる。一軸延伸の延伸倍率は、好ましくは３～７倍である。延伸は、染色後に行ってもよいし、染色しながら行ってもよい。また、延伸後に染色を行ってもよい。必要に応じて、ＰＶＡ系樹脂フィルムに、膨潤処理、架橋処理、洗浄処理、乾燥処理等が施される。 A specific example of a polarizer made of a single-layer resin film is a PVA-based resin film that has been dyed with iodine and stretched (typically, uniaxially stretched). The dyeing with iodine is performed, for example, by immersing the PVA-based film in an aqueous iodine solution. The stretching ratio for uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after dyeing or while dyeing. Dyeing may also be performed after stretching. If necessary, the PVA-based resin film may be subjected to swelling, crosslinking, washing, drying, etc.
　積層体から構成される偏光子の具体例としては、樹脂基材とこの樹脂基材に積層されたＰＶＡ系樹脂層（ＰＶＡ系樹脂フィルム）との積層体、又は、樹脂基材とこの樹脂基材に塗布形成されたＰＶＡ系樹脂層との積層体から構成される偏光子が挙げられる。樹脂基材とこの樹脂基材に塗布形成されたＰＶＡ系樹脂層との積層体から構成される偏光子は、例えば、ＰＶＡ系樹脂溶液を樹脂基材に塗布し、乾燥させて樹脂基材上にＰＶＡ系樹脂層を形成して、樹脂基材とＰＶＡ系樹脂層との積層体を得た後、この積層体を延伸及び染色してＰＶＡ系樹脂層を偏光子とすることにより作製することができる。本実施形態において、延伸は、代表的には積層体をホウ酸水溶液中に浸漬させて延伸することを含む。さらに、延伸は、必要に応じて、ホウ酸水溶液中での延伸の前に積層体を高温（例えば、９５℃以上）で空中延伸することを含んでもよい。得られた樹脂基材／偏光子の積層体は、そのまま用いてもよく（すなわち、樹脂基材を偏光子の保護層としてもよく）、樹脂基材／偏光子の積層体から樹脂基材をはく離し、このはく離面に目的に応じた任意の適切な保護層を積層して用いてもよい。このような偏光子の製造方法の詳細は、例えば、特開２０１２－７３５８０号公報に記載されている。この公報は、その全体の記載が本明細書に参考として援用される。 Specific examples of polarizers made of a laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a polarizer made of a laminate of a resin substrate and a PVA-based resin layer applied to the resin substrate. A polarizer made of a laminate of a resin substrate and a PVA-based resin layer applied to the resin substrate can be produced, for example, by applying a PVA-based resin solution to the resin substrate, drying the resin substrate to form a PVA-based resin layer on the resin substrate, obtaining a laminate of the resin substrate and the PVA-based resin layer, and then stretching and dyeing the laminate to make the PVA-based resin layer into a polarizer. In this embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching it. Furthermore, stretching may include, as necessary, stretching the laminate in air at a high temperature (e.g., 95°C or higher) before stretching in the aqueous boric acid solution. The obtained resin substrate/polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled off from the resin substrate/polarizer laminate, and any suitable protective layer may be laminated on the peeled surface depending on the purpose. Details of the method for producing such a polarizer are described, for example, in JP 2012-73580 A. The entire disclosure of this publication is incorporated herein by reference.
　偏光子１１の厚みは、好ましくは１５μｍ以下であり、より好ましくは１μｍ～１２μｍであり、さらに好ましくは３μｍ～１０μｍであり、特に好ましくは３μｍ～８μｍである。 The thickness of the polarizer 11 is preferably 15 μm or less, more preferably 1 μm to 12 μm, even more preferably 3 μm to 10 μm, and particularly preferably 3 μm to 8 μm.
　偏光子１１は、好ましくは、波長３８０ｎｍ～７８０ｎｍの範囲内の何れかの波長で吸収二色性を示す。偏光子１１の単体透過率は、好ましくは４０．０％～４５．０％であり、より好ましくは４１．５％～４３．５％である。偏光子１１の偏光度は、好ましくは９７．０％以上であり、より好ましくは９９．０％以上であり、さらに好ましくは９９．９％以上である。 The polarizer 11 preferably exhibits absorption dichroism at any wavelength within the range of 380 nm to 780 nm. The single transmittance of the polarizer 11 is preferably 40.0% to 45.0%, and more preferably 41.5% to 43.5%. The degree of polarization of the polarizer 11 is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.
　（保護フィルム１２、１３）
　保護フィルム１２、１３としては、任意の適切な樹脂フィルムが用いられる。樹脂フィルムの形成材料としては、例えば、（メタ）アクリル系樹脂、ジアセチルセルロース、トリアセチルセルロース等のセルロース系樹脂、ノルボルネン系樹脂等のシクロオレフィン系樹脂、ポリプロピレン等のオレフィン系樹脂、ポリエチレンテレフタレート系樹脂等のエステル系樹脂、ポリアミド系樹脂、ポリカーボネート系樹脂、これらの共重合体樹脂等が挙げられる。なお、「（メタ）アクリル系樹脂」とは、アクリル系樹脂及び／又はメタクリル系樹脂を意味する。保護フィルム１２、１３の形成材料は互いに同じであっても異なるものであってもよい。 (Protective films 12, 13)
Any suitable resin film is used as the protective films 12 and 13. Examples of materials for forming the resin film include (meth)acrylic resins, cellulose resins such as diacetyl cellulose and triacetyl cellulose, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, ester resins such as polyethylene terephthalate resins, polyamide resins, polycarbonate resins, and copolymer resins thereof. Note that "(meth)acrylic resin" means acrylic resin and/or methacrylic resin. The materials for forming the protective films 12 and 13 may be the same or different from each other.
　保護フィルム１２、１３の厚みは、代表的には１０μｍ～１００μｍであり、好ましくは２０μｍ～４０μｍである。保護フィルム１２、１３の厚みは互いに同じであっても異なるものであってもよい。 The thickness of the protective films 12 and 13 is typically 10 μm to 100 μm, and preferably 20 μm to 40 μm. The thicknesses of the protective films 12 and 13 may be the same or different.
　保護フィルム１２、１３の偏光子１１と反対側の表面には、必要に応じて、ハードコート処理、反射防止処理、スティッキング防止処理、アンチグレア処理等の表面処理が施されていてもよい。さらに／又は、保護フィルム１２、１３の偏光子１１と反対側の表面には、必要に応じて、偏光サングラスを介して視認する場合の視認性を改善する処理（代表的には、（楕）円偏光機能を付与する処理、超高位相差を付与する処理）が施されていてもよい。なお、表面処理が施されて表面処理層が形成される場合、保護フィルム１２、１３の厚みは、表面処理層を含めた厚みである。　 The surface of the protective films 12, 13 opposite the polarizer 11 may be subjected to a surface treatment such as a hard coat treatment, an anti-reflection treatment, an anti-sticking treatment, or an anti-glare treatment, if necessary. Furthermore, the surface of the protective films 12, 13 opposite the polarizer 11 may be subjected to a treatment to improve visibility when viewed through polarized sunglasses (typically, a treatment to impart an (elliptical) polarizing function or a treatment to impart an ultra-high phase difference), if necessary. Note that when a surface treatment is performed to form a surface treatment layer, the thickness of the protective films 12, 13 includes the thickness of the surface treatment layer.
　なお、保護フィルム１２、１３は、任意の適切な接着剤層（図示せず）を介して、それぞれ偏光子１１に貼り合わせられて、積層されている。接着剤層を構成する接着剤として、代表的にはＰＶＡ系接着剤又は活性化エネルギー線硬化型接着剤が挙げられる。 The protective films 12 and 13 are laminated by being attached to the polarizer 11 via any suitable adhesive layer (not shown). Typical examples of the adhesive that constitutes the adhesive layer include a PVA-based adhesive or an activated energy ray curing adhesive.
　［位相差フィルム２］
　位相差フィルム２は、例えば、広視野角を付与する補償板であってもよいし、偏光膜と共に用いられて円偏光を生成するための１／２波長板や１／４波長板等の位相差板（円偏光板）であってもよい。位相差フィルム２の厚みは、例えば、１～２００μｍである。 [Retardation film 2]
The retardation film 2 may be, for example, a compensation plate that provides a wide viewing angle, or a retardation plate (circular polarizing plate) such as a half-wave plate or a quarter-wave plate that is used together with a polarizing film to generate circularly polarized light. The thickness of the retardation film 2 is, for example, 1 to 200 μm.
　位相差フィルム２は、例えば、重合性液晶を重合させることにより形成される層又は樹脂で形成される。重合性液晶とは、重合性基を有し、且つ、液晶性を有する化合物である。重合性基とは、重合反応に関与する基を意味し、光重合性基であることが好ましい。ここで、光重合性基とは、光重合開始剤から発生した活性ラジカルや酸などによって重合反応に関与し得る基のことをいう。重合性基としては、ビニル基、ビニルオキシ基、１－クロロビニル基、イソプロペニル基、４－ビニルフェニル基、アクリロイルオキシ基、メタクリロイルオキシ基、オキシラニル基、オキセタニル基等が挙げられる。中でも、アクリロイルオキシ基、メタクリロイルオキシ基、ビニルオキシ基、オキシラニル基及びオキセタニル基が好ましく、アクリロイルオキシ基がより好ましい。重合性液晶が有する液晶性はサーモトロピック性液晶でもリオトロピック液晶でもよく、サーモトロピック液晶を秩序度で分類すると、ネマチック液晶でもスメクチック液晶でもよい。
　また、位相差フィルム２を形成する樹脂としては、例えば、ポリアリレート、ポリアミド、ポリイミド、ポリエステル、ポリアリールエーテルケトン、ポリアミドイミド、ポリエステルイミド、ポリビニルアルコール、ポリフマル酸エステル、ポリエーテルサルフォン、ポリサルフォン、ノルボルネン樹脂、ポリカーボネート樹脂、セルロース樹脂及びポリウレタンが挙げられる。これらの樹脂は、単独で用いてもよく、組み合わせて用いてもよい。 The retardation film 2 is formed of, for example, a layer or resin formed by polymerizing a polymerizable liquid crystal. The polymerizable liquid crystal is a compound having a polymerizable group and liquid crystallinity. The polymerizable group means a group involved in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group means a group that can be involved in a polymerization reaction by an active radical or an acid generated from a photopolymerization initiator. Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferable, and an acryloyloxy group is more preferable. The liquid crystallinity of the polymerizable liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, and when the thermotropic liquid crystal is classified by the degree of order, it may be a nematic liquid crystal or a smectic liquid crystal.
Examples of the resin forming the retardation film 2 include polyarylate, polyamide, polyimide, polyester, polyaryletherketone, polyamideimide, polyesterimide, polyvinyl alcohol, polyfumaric acid ester, polyethersulfone, polysulfone, norbornene resin, polycarbonate resin, cellulose resin, and polyurethane. These resins may be used alone or in combination.
　なお、位相差フィルム２は、任意の適切な接着剤層又は粘着剤層（図示せず）を介して、偏光フィルム１（保護フィルム１３）に貼り合わせられて、積層されている。接着剤層を構成する接着剤として、代表的にはＰＶＡ系接着剤又は活性化エネルギー線硬化型接着剤が挙げられる。 The retardation film 2 is laminated by being attached to the polarizing film 1 (protective film 13) via any suitable adhesive layer or pressure sensitive adhesive layer (not shown). Typical examples of the adhesive that constitutes the adhesive layer include a PVA-based adhesive or an activated energy ray curing adhesive.
　［粘着剤層３］
　粘着剤層３は、はく離ライナー４の片面に粘着剤を塗布し、この塗布した粘着剤をオーブン等で加熱して乾燥させることで硬化して形成される。また、はく離ライナー４だけではなく、偏光板１０を構成する位相差フィルム２にも粘着剤層３を形成する場合もある。
　粘着剤の加熱温度は、１００℃～１６０℃の範囲に設定することが好ましく、１４０℃～１６０℃の範囲に設定することがより好ましい。この加熱温度で、２０秒～３分加熱することが好ましく、１分～３分加熱することがより好ましい。 [Pressure-sensitive adhesive layer 3]
The adhesive layer 3 is formed by applying an adhesive to one side of the release liner 4 and then heating and drying the applied adhesive in an oven or the like to harden it. In some cases, the adhesive layer 3 is formed not only on the release liner 4 but also on the retardation film 2 constituting the polarizing plate 10.
The heating temperature of the adhesive is preferably set in the range of 100° C. to 160° C., and more preferably in the range of 140° C. to 160° C. Heating at this heating temperature is preferably performed for 20 seconds to 3 minutes, and more preferably for 1 minute to 3 minutes.
　粘着剤層３を形成する粘着剤の具体例としては、アクリル系粘着剤、ゴム系粘着剤、シリコーン系粘着剤、ポリエステル系粘着剤、ウレタン系粘着剤、エポキシ系粘着剤、及び、ポリエーテル系粘着剤が挙げられる。粘着剤のベース樹脂を形成するモノマーの種類、数、組み合わせ及び配合比、並びに、架橋剤の配合量、反応温度、反応時間等を調整することにより、目的に応じた所望の特性を有する粘着剤を調製することができる。粘着剤のベース樹脂は、単独で用いてもよく、２種以上を組み合わせて用いてもよい。透明性、加工性及び耐久性などの観点から、アクリル系粘着剤が好ましい。粘着剤層を構成する粘着剤の詳細は、例えば、特開２０１４－１１５４６８号公報に記載されており、当該公報の記載は本明細書に参考として援用されている。粘着剤層の厚みは、例えば１０μｍ～１００μｍにすることができる。 Specific examples of adhesives forming the adhesive layer 3 include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, number, combination, and compounding ratio of the monomers forming the base resin of the adhesive, as well as the compounding amount of the crosslinking agent, reaction temperature, reaction time, etc., an adhesive having the desired properties according to the purpose can be prepared. The base resin of the adhesive may be used alone or in combination of two or more types. From the viewpoints of transparency, processability, durability, etc., acrylic adhesives are preferred. Details of the adhesives constituting the adhesive layer are described, for example, in JP 2014-115468 A, and the description of this publication is incorporated by reference in this specification. The thickness of the adhesive layer can be, for example, 10 μm to 100 μm.
　［はく離ライナー４］
　はく離ライナー４としては、任意の適切なはく離ライナーを採用することができる。具体例としては、はく離剤により表面コートされたプラスチックフィルム、不織布又は紙が挙げられる。はく離剤の具体例としては、シリコーン系はく離剤、フッ素系はく離剤、長鎖アルキルアクリレート系はく離剤が挙げられる。プラスチックフィルムの具体例としては、ポリエチレンテレフタレート（ＰＥＴ）フィルム、ポリエチレンフィルム、ポリプロピレンフィルムが挙げられる。はく離ライナー４の厚みは、例えば１０μｍ～１００μｍとすることができる。 [Release Liner 4]
Any appropriate release liner can be used as the release liner 4. Specific examples include plastic films, nonwoven fabrics, or papers whose surfaces are coated with a release agent. Specific examples of release agents include silicone-based release agents, fluorine-based release agents, and long-chain alkyl acrylate-based release agents. Specific examples of plastic films include polyethylene terephthalate (PET) films, polyethylene films, and polypropylene films. The thickness of the release liner 4 can be, for example, 10 μm to 100 μm.
　［表面保護フィルム５］
　表面保護フィルム５は、代表的には、基材と粘着剤層とを有する。本実施形態において、表面保護フィルム５の厚みは、例えば３０μｍ以上である。表面保護フィルム５の厚みの上限は、例えば１５０μｍである。なお、本明細書において、「表面保護フィルムの厚み」とは、基材と粘着剤層との合計厚みをいう。 [Surface protection film 5]
The surface protection film 5 typically has a substrate and a pressure-sensitive adhesive layer. In this embodiment, the thickness of the surface protection film 5 is, for example, 30 μm or more. The upper limit of the thickness of the surface protection film 5 is, for example, 150 μm. In this specification, the "thickness of the surface protection film" refers to the total thickness of the substrate and the pressure-sensitive adhesive layer.
　基材は、任意の適切な樹脂フィルムで構成することができる。樹脂フィルムの形成材料としては、ポリエチレンテレフタレート系樹脂等のエステル系樹脂、ノルボルネン系樹脂等のシクロオレフィン系樹脂、ポリプロピレン等のオレフィン系樹脂、ポリアミド系樹脂、ポリカーボネート系樹脂、これらの共重合体樹脂等が挙げられる。好ましくは、エステル系樹脂（特に、ポリエチレンテレフタレート系樹脂）である。 The substrate can be made of any suitable resin film. Materials for forming the resin film include ester-based resins such as polyethylene terephthalate-based resins, cycloolefin-based resins such as norbornene-based resins, olefin-based resins such as polypropylene, polyamide-based resins, polycarbonate-based resins, and copolymer resins of these. Ester-based resins (particularly polyethylene terephthalate-based resins) are preferred.
　粘着剤層を形成する粘着剤としては、任意の適切な粘着剤を採用することができる。粘着剤のベース樹脂としては、例えば、アクリル系樹脂、スチレン系樹脂、シリコーン系樹脂、ウレタン系樹脂、ゴム系樹脂が挙げられる。 Any suitable adhesive can be used as the adhesive that forms the adhesive layer. Examples of the base resin of the adhesive include acrylic resin, styrene resin, silicone resin, urethane resin, and rubber resin.
　＜本実施形態に係る製造方法＞
　以上に説明した構成を有する光学積層体１００を製造するための本実施形態に係る光学積層体１００の製造方法について、以下に説明する。
　図２は、本実施形態に係る光学積層体１００の製造方法の概略工程を示すフロー図である。
　図２に示すように、本実施形態に係る製造方法は、偏光フィルム製造工程ＳＴ１と、位相差フィルム貼合工程ＳＴ２と、はく離ライナー貼合工程ＳＴ３と、検査工程ＳＴ４と、表面保護フィルム貼合工程ＳＴ５と、を含む。以下、各工程ＳＴ１～ＳＴ５について説明する。 <Production method according to this embodiment>
A method for producing the optical laminate 100 according to this embodiment for producing the optical laminate 100 having the configuration described above will be described below.
FIG. 2 is a flow diagram showing an outline of the steps of a method for producing the optical laminate 100 according to this embodiment.
2, the manufacturing method according to the present embodiment includes a polarizing film manufacturing process ST1, a retardation film bonding process ST2, a release liner bonding process ST3, an inspection process ST4, and a surface protection film bonding process ST5. Each of the processes ST1 to ST5 will be described below.
　［偏光フィルム製造工程ＳＴ１］
　偏光フィルム製造工程ＳＴ１では、長尺帯状の樹脂フィルムを原反フィルムとして、この原反フィルムを長手方向（ＭＤ方向）に搬送しながら各種の処理浴に浸漬させて、染色処理や延伸処理等の各種の処理を施すことによって、長尺帯状の偏光子１１を製造する。そして、長尺帯状の偏光子１１に長尺帯状の保護フィルム１２、１３を貼り合わせることで、長尺帯状の偏光フィルム１を製造する。 [Polarizing film manufacturing process ST1]
In the polarizing film manufacturing process ST1, a long strip-shaped resin film is used as a raw film, and this raw film is immersed in various treatment baths while being transported in the longitudinal direction (MD direction) and subjected to various treatments such as dyeing and stretching to manufacture a long strip-shaped polarizer 11. Then, long strip-shaped protective films 12 and 13 are bonded to the long strip-shaped polarizer 11 to manufacture a long strip-shaped polarizing film 1.
　［位相差フィルム貼合工程ＳＴ２］
　位相差フィルム貼合工程ＳＴ２では、長尺帯状の偏光フィルム１の片面（保護フィルム１３）に長尺帯状の位相差フィルム２を貼り合わせることで、長尺帯状の偏光板１０を製造する。
　なお、光学積層体１００が位相差フィルム２を備えない（偏光板１０が位相差フィルム２を備えない）場合には、位相差フィルム貼合工程ＳＴ２は不要である。 [Retardation film bonding process ST2]
In the retardation film laminating step ST2, a long strip of retardation film 2 is laminated to one surface (protective film 13) of a long strip of polarizing film 1, thereby producing a long strip of polarizing plate 10.
In addition, when the optical laminate 100 does not include the retardation film 2 (when the polarizing plate 10 does not include the retardation film 2), the retardation film bonding step ST2 is not necessary.
　［はく離ライナー貼合工程ＳＴ３］
　はく離ライナー貼合工程ＳＴ３では、長尺帯状のはく離ライナー４を長手方向（ＭＤ方向）に搬送しながら粘着剤を塗布し、この塗布した粘着剤をオーブン等で加熱して乾燥させることで硬化させ、粘着剤層３を形成する粘着剤層形成工程を実行する。そして、長尺帯状のはく離ライナー４に形成された粘着剤層３を介してはく離ライナー４を長尺帯状の偏光板１０に貼り合わせる。具体的には、長尺帯状のはく離ライナー４（粘着剤層３付きはく離ライナー４）の粘着剤層３側を長尺帯状の偏光板１０の片面（位相差フィルム２）に貼り合わせる。これにより、偏光板１０と粘着剤層３とはく離ライナー４とが積層された第２中間体Ｍ２を製造する。
　なお、はく離ライナー４だけではなく、偏光板１０を構成する位相差フィルム２にも粘着剤層３を形成して、粘着剤層３付き偏光板１０としてもよい。そして、はく離ライナー４の粘着剤層３側と、偏光板１０の粘着剤層側とを貼り合わせて、第２中間体Ｍ２を製造することも可能である。 [Release liner attachment step ST3]
In the release liner laminating step ST3, an adhesive is applied to the long strip release liner 4 while it is being transported in the longitudinal direction (MD direction), and the applied adhesive is heated in an oven or the like to dry and harden, thereby forming an adhesive layer 3. Then, the release liner 4 is bonded to the long strip polarizing plate 10 via the adhesive layer 3 formed on the long strip release liner 4. Specifically, the adhesive layer 3 side of the long strip release liner 4 (release liner 4 with adhesive layer 3) is bonded to one side (phase difference film 2) of the long strip polarizing plate 10. In this way, a second intermediate M2 in which the polarizing plate 10, the adhesive layer 3, and the release liner 4 are laminated is manufactured.
The pressure-sensitive adhesive layer 3 may be formed not only on the release liner 4 but also on the retardation film 2 constituting the polarizing plate 10 to obtain a polarizing plate 10 with a pressure-sensitive adhesive layer 3. Then, the pressure-sensitive adhesive layer 3 side of the release liner 4 and the pressure-sensitive adhesive layer side of the polarizing plate 10 can be bonded together to produce the second intermediate M2.
　図３は、はく離ライナー貼合工程ＳＴ３を実行する装置の概略構成例を模式的に示す図である。図３（ａ）は、装置の側面図（各フィルムの搬送方向（ＭＤ方向）に直交する水平方向（ＴＤ方向）から見た図）である。図３（ａ）に示す矢符は、各フィルムの搬送方向を意味する。図３（ｂ）は、図３（ａ）に示す貼合ローラＲ１におけるフィルムの進入角度を説明する側面視断面図である。
　本発明では、貼合ローラによって貼り合わせる一方のフィルムを第１光学フィルムＦ１とし、他方のフィルムを第２光学フィルムＦ２としている。はく離ライナー貼合工程ＳＴ３では、第１光学フィルムＦ１は、偏光板１０又は粘着剤層３付き偏光板１０であり、第２光学フィルムＦ２は、粘着剤層３付きはく離ライナー４である。この第１光学フィルムＦ１と第２光学フィルムＦ２とが、粘着剤層３を介して、貼合ローラＲ１によって貼り合わされ、第１光学フィルムＦ１と第２光学フィルムＦ２との積層体Ｆ３が製造される。はく離ライナー貼合工程ＳＴ３では、積層体Ｆ３は、第２中間体Ｍ２である。 Figure 3 is a schematic diagram showing an example of the schematic configuration of an apparatus for performing the release liner lamination step ST3. Figure 3(a) is a side view of the apparatus (viewed from a horizontal direction (TD direction) perpendicular to the conveying direction (MD direction) of each film). The arrows shown in Figure 3(a) indicate the conveying direction of each film. Figure 3(b) is a side view cross-sectional view explaining the approach angle of the film in the lamination roller R1 shown in Figure 3(a).
In the present invention, one of the films to be bonded by the lamination roller is the first optical film F1, and the other film is the second optical film F2. In the release liner bonding step ST3, the first optical film F1 is a polarizing plate 10 or a polarizing plate 10 with a pressure-sensitive adhesive layer 3, and the second optical film F2 is a release liner 4 with a pressure-sensitive adhesive layer 3. The first optical film F1 and the second optical film F2 are bonded together by the lamination roller R1 via the pressure-sensitive adhesive layer 3 to produce a laminate F3 of the first optical film F1 and the second optical film F2. In the release liner bonding step ST3, the laminate F3 is the second intermediate M2.
　具体的には、図３（ａ）に示すように、貼合ローラＲ１の入側（貼合ローラＲ１に対して、第１光学フィルムＦ１の搬送方向上流側であり、図３（ａ）に示す例では、貼合ローラＲ１の左側）に第１光学フィルムＦ１に接触する第１搬送ローラＲ２が配置され、第１搬送ローラＲ２によって、第１光学フィルムＦ１が貼合ローラＲ１に搬送される。同様に、貼合ローラＲ１の入側（貼合ローラＲ１に対して、第２光学フィルムＦ２の搬送方向上流側であり、図３（ａ）に示す例では、貼合ローラＲ１の左側）に第２光学フィルムＦ２に接触する第２搬送ローラＲ３が配置され、第２搬送ローラＲ３によって、第２光学フィルムＦ２が貼合ローラＲ１に搬送される。
　第１搬送ローラＲ２は、貼合ローラＲ１に対する位置（本実施形態では、上下方向の位置）を調整可能になっている。図３（ａ）に示す例では、第１搬送ローラＲ２は、実線で示す最上部の位置から、破線で示す位置を経て、一点鎖線で示す最下部の位置に移動可能である。例えば、第１搬送ローラＲ２の回転軸が軸受を介して一軸アクチュエータに取り付けられ、この一軸アクチュエータを駆動することで、第１搬送ローラＲ２の位置を調整可能にする構成を採用可能である。
　一方、第２搬送ローラＲ３は、所定の位置に固定されている。 Specifically, as shown in Fig. 3(a), a first transport roller R2 in contact with the first optical film F1 is disposed on the entry side of the lamination roller R1 (upstream side in the transport direction of the first optical film F1 with respect to the lamination roller R1, and to the left of the lamination roller R1 in the example shown in Fig. 3(a)), and the first optical film F1 is transported to the lamination roller R1 by the first transport roller R2. Similarly, a second transport roller R3 in contact with the second optical film F2 is disposed on the entry side of the lamination roller R1 (upstream side in the transport direction of the second optical film F2 with respect to the lamination roller R1, and to the left of the lamination roller R1 in the example shown in Fig. 3(a)), and the second transport roller R3 transports the second optical film F2 to the lamination roller R1.
The position of the first conveying roller R2 relative to the lamination roller R1 (in this embodiment, the position in the vertical direction) is adjustable. In the example shown in Fig. 3(a), the first conveying roller R2 can move from the uppermost position shown by the solid line, through the position shown by the dashed line, to the lowermost position shown by the dashed line. For example, a configuration can be adopted in which the rotation shaft of the first conveying roller R2 is attached to a single-axis actuator via a bearing, and the position of the first conveying roller R2 can be adjusted by driving the single-axis actuator.
On the other hand, the second transport roller R3 is fixed at a predetermined position.
　貼合ローラＲ１は、第１ローラＲ１ａと、第１ローラＲ１ａに対向（図３に示す例では上下方向に対向）して配置された第２ローラＲ１ｂと、から構成されている。
　第１ローラＲ１ａは、第１光学フィルムＦ１に接触して、第１ローラＲ１ａと第２ローラＲ１ｂとの間に第１光学フィルムＦ１を搬送するローラである。第１ローラＲ１ａは、その表面が樹脂（本実施形態では、シリコンゴム）から形成された樹脂ローラである。
　第２ローラＲ１ｂは、第２光学フィルムＦ２に接触して、第１ローラＲ１ａと第２ローラＲ１ｂとの間に第２光学フィルムＦ２を搬送するローラである。第２ローラＲ１ｂは、その表面が金属（本実施形態では、鉄）から形成された金属ローラである。
　第１光学フィルムＦ１及び第２光学フィルムＦ２が第１ローラＲ１ａと第２ローラＲ１ｂとの間に進入することで、第１光学フィルムＦ１と第２光学フィルムＦ２とが貼り合わせられ、第１光学フィルムＦ１と第２光学フィルムＦ２との積層体Ｆ３が製造される。積層体Ｆ３は、搬送ローラＲ４によって搬送され、巻取ローラ（図示せず）で巻き取られる。 The lamination roller R1 is composed of a first roller R1a and a second roller R1b disposed opposite the first roller R1a (opposing in the vertical direction in the example shown in FIG. 3).
The first roller R1a is a roller that comes into contact with the first optical film F1 and transports the first optical film F1 between the first roller R1a and the second roller R1b. The first roller R1a is a resin roller whose surface is made of resin (silicone rubber in this embodiment).
The second roller R1b is a roller that comes into contact with the second optical film F2 and transports the second optical film F2 between the first roller R1a and the second roller R1b. The second roller R1b is a metal roller whose surface is made of metal (iron in this embodiment).
The first optical film F1 and the second optical film F2 enter between the first roller R1a and the second roller R1b, whereby the first optical film F1 and the second optical film F2 are bonded together to produce a laminate F3 of the first optical film F1 and the second optical film F2. The laminate F3 is transported by a transport roller R4 and taken up by a take-up roller (not shown).
　図３（ｂ）に示すように、第１ローラＲ１ａの回転中心Ｃ１及び第２ローラＲ１ｂの回転中心Ｃ２に直交する断面において、第１ローラＲ１ａの回転中心Ｃ１と第２ローラの回転中心Ｃ２とを通る直線（仮想直線）を直線ＣＬとする。直線ＣＬに直交し、貼合ローラＲ１の出側（第１光学フィルムＦ１及び第２光学フィルムＦ２の搬送方向下流側であり、図３（ｂ）に示す例では、貼合ローラＲ１の右側）に向いたベクトル（仮想ベクトル）をベクトルＶＣとする。このとき、第１光学フィルムＦ１の貼合ローラＲ１への進入角度αは、ベクトルＶＣと、貼合ローラＲ１に接触するまでの第１光学フィルムＦ１の進行方向を示すベクトルとの成す角度を意味する。また、第２光学フィルムＦ２の貼合ローラＲ１への進入角度βは、ベクトルＶＣと、貼合ローラＲ１に接触するまでの第２光学フィルムＦ２の進行方向を示すベクトルとの成す角度を意味する。
　そして、はく離ライナー貼合工程ＳＴ３では、積層体Ｆ３の長手方向（ＭＤ方向）に直交する方向（ＴＤ方向）のカール値が所定の範囲内となるように、第１光学フィルムＦ１の貼合ローラＲ１への進入角度αが調整される。具体的には、第１搬送ローラＲ２の貼合ローラＲ１に対する位置を上下方向に調整することで、進入角度αが調整される。図３（ａ）に実線で示す最上部の位置に第１搬送ローラＲ２が位置するときに、進入角度αは最も小さい０°となり、一点鎖線で示す最下部の位置に第１搬送ローラＲ２が位置するときに、進入角度αは最も大きな値となる。 As shown in FIG. 3B, in a cross section perpendicular to the rotation center C1 of the first roller R1a and the rotation center C2 of the second roller R1b, a straight line (virtual line) passing through the rotation center C1 of the first roller R1a and the rotation center C2 of the second roller is defined as a straight line CL. A vector (virtual vector) perpendicular to the straight line CL and directed toward the exit side of the lamination roller R1 (the downstream side in the conveying direction of the first optical film F1 and the second optical film F2, and in the example shown in FIG. 3B, the right side of the lamination roller R1) is defined as a vector VC. At this time, the approach angle α of the first optical film F1 to the lamination roller R1 means the angle formed by the vector VC and the vector indicating the traveling direction of the first optical film F1 until it contacts the lamination roller R1. In addition, the approach angle β of the second optical film F2 to the lamination roller R1 means the angle formed by the vector VC and the vector indicating the traveling direction of the second optical film F2 until it contacts the lamination roller R1.
In the release liner lamination step ST3, the approach angle α of the first optical film F1 to the lamination roller R1 is adjusted so that the curl value in the direction (TD direction) perpendicular to the longitudinal direction (MD direction) of the laminate F3 falls within a predetermined range. Specifically, the approach angle α is adjusted by adjusting the position of the first transport roller R2 relative to the lamination roller R1 in the vertical direction. When the first transport roller R2 is located at the top position shown by the solid line in Fig. 3(a), the approach angle α is the smallest, 0°, and when the first transport roller R2 is located at the bottom position shown by the dashed line, the approach angle α is the largest.
　以下、カール値の測定方法について説明する。
　図４は、本実施形態で実施したカール値の測定方法の概要を説明する説明図である。
　図４（ａ）に示すように、長尺の第２中間体Ｍ２のＴＤ方向に沿って、複数枚の製品サイズ（例えば、スマートフォン用に使用される長辺１６０ｍｍ×短辺８０ｍｍ）の矩形の第２中間体サンプルＭ２１を切り出す。図４（ａ）では、便宜上、３枚の中間体サンプルＭ２１を図示しているが、実際には、これに限られない。これを複数の第２中間体Ｍ２について実施することで得られた計１００枚の第２中間体サンプルＭ２１について、カール値を測定する。なお、図４（ｂ）に示すように、第２中間体サンプルＭ２１を切り出す際には、第２中間体Ｍ２のＭＤ方向（図１に示す偏光子１１の吸収軸の方向に相当）が、第２中間体サンプルＭ２１の長辺及び短辺に対して４５°となるように、斜めに切り出す。 The method for measuring the curl value will be described below.
FIG. 4 is an explanatory diagram for explaining an outline of the method for measuring the curl value implemented in this embodiment.
As shown in FIG. 4(a), a plurality of rectangular second intermediate samples M21 of product size (for example, long side 160 mm × short side 80 mm used for smartphones) are cut out along the TD direction of the long second intermediate M2. In FIG. 4(a), for convenience, three intermediate samples M21 are shown, but in reality, this is not limited to this. The curl value is measured for a total of 100 second intermediate samples M21 obtained by performing this for a plurality of second intermediates M2. Note that, as shown in FIG. 4(b), when cutting out the second intermediate sample M21, the second intermediate sample M21 is cut out obliquely so that the MD direction of the second intermediate M2 (corresponding to the direction of the absorption axis of the polarizer 11 shown in FIG. 1) is at 45° to the long side and short side of the second intermediate sample M21.
　図４（ｃ）に示すように、カール値を測定する際には、第２中間体サンプルＭ２１の下側が凸になるように（第２中間体サンプルＭ２１の４つの角部の反りが鉛直方向上方に向かうように）、第２中間体サンプルＭ２１を平坦な載置台２０上に載置し、第２中間体サンプルＭ２１の４つの角部のそれぞれについて、載置台２０の上面から角部までの鉛直方向の距離Ｈを測定する。第２中間体サンプルＭ２１の４つの角部は、第２中間体Ｍ２から切り出す前の状態において、第２中間体Ｍ２のＴＤ方向の両端に位置する角部ＴＤ１、ＴＤ２と、第２中間体Ｍ２のＭＤ方向の両端に位置する角部ＭＤ１、ＭＤ２である。距離Ｈは、第２中間体サンプルＭ２１の角部近傍に鉛直方向に延びるスケールを立て、このスケールの目盛りを目視で読み取ることで測定する。 As shown in FIG. 4(c), when measuring the curl value, the second intermediate sample M21 is placed on a flat mounting table 20 so that the bottom side of the second intermediate sample M21 is convex (so that the warping of the four corners of the second intermediate sample M21 faces vertically upward), and the vertical distance H from the upper surface of the mounting table 20 to each of the four corners of the second intermediate sample M21 is measured. The four corners of the second intermediate sample M21 are corners TD1 and TD2 located at both ends of the second intermediate M2 in the TD direction and corners MD1 and MD2 located at both ends of the second intermediate M2 in the MD direction before being cut out from the second intermediate M2. The distance H is measured by erecting a scale extending vertically near the corners of the second intermediate sample M21 and visually reading the graduations of this scale.
　第２中間体サンプルＭ２１の下側が凸になるように載置台２０上に載置した際、第２中間体サンプルＭ２１のはく離ライナー４の位置する側が下になる（偏光板１０の位置する側が上になる）場合をプラスのカールとし、角部ＴＤ１、ＴＤ２のそれぞれについて測定した距離Ｈの大きい方をそのままＴＤ方向のカール値として算出する。また、角部ＭＤ１、ＭＤ２のそれぞれについて測定した距離Ｈの大きい方をそのままＭＤ方向のカール値として算出する。
　一方、第２中間体サンプルＭ２１の下側が凸になるように載置台２０上に載置した際、第２中間体サンプルＭ２１のはく離ライナー４の位置する側が上になる（偏光板１０の位置する側が下になる）場合をマイナスのカールとし、角部ＴＤ１、ＴＤ２のそれぞれについて測定した距離Ｈに－１を乗算し、その絶対値の大きい方をＴＤ方向のカール値として算出する。また、角部ＭＤ１、ＭＤ２のそれぞれについて測定した距離Ｈに－１を乗算し、その絶対値の大きい方をＭＤ方向のカール値として算出する。
　そして、１００枚の第２中間体サンプルＭ２１のそれぞれについて測定したＴＤ方向のカール値の平均値を、第２中間体Ｍ２のＴＤ方向のカール値とする。同様に、１００枚の第２中間体サンプルＭ２１のそれぞれについて測定したＭＤ方向のカール値の平均値を、第２中間体Ｍ２のＭＤ方向のカール値とする。
　なお、後述の光学積層体１００のＴＤ方向のカール値及びＭＤ方向のカール値についても、図４を参照して説明した上記と同様の測定方法で測定可能である。 When the second intermediate sample M21 is placed on the mounting table 20 so that the bottom side thereof is convex, the side where the release liner 4 of the second intermediate sample M21 is located is the bottom (the side where the polarizing plate 10 is located is the top), which is regarded as a positive curl, and the larger of the distances H measured for each of the corners TD1 and TD2 is calculated as the curl value in the TD direction. Also, the larger of the distances H measured for each of the corners MD1 and MD2 is calculated as the curl value in the MD direction.
On the other hand, when the second intermediate sample M21 is placed on the mounting table 20 so that the bottom side is convex, the side of the second intermediate sample M21 where the release liner 4 is located is on the top (the side where the polarizing plate 10 is located is on the bottom), which is regarded as a negative curl, and the distance H measured for each of the corners TD1 and TD2 is multiplied by -1, and the larger absolute value is calculated as the curl value in the TD direction. Also, the distance H measured for each of the corners MD1 and MD2 is multiplied by -1, and the larger absolute value is calculated as the curl value in the MD direction.
The average of the TD curl values measured for each of the 100 second intermediate samples M21 is defined as the TD curl value of the second intermediate M2. Similarly, the average of the MD curl values measured for each of the 100 second intermediate samples M21 is defined as the MD curl value of the second intermediate M2.
The curl value in the TD direction and the curl value in the MD direction of the optical laminate 100 described later can also be measured by the same measurement method as described above with reference to FIG.
　図５は、はく離ライナー貼合工程ＳＴ３で製造された積層体Ｆ３（第２中間体Ｍ２）のＴＤ方向のカール値及びＭＤ方向のカール値を測定した結果の一例を示す図である。具体的には、図５は、第１光学フィルムＦ１が偏光板１０であり、第２光学フィルムＦ２が粘着剤層３付きはく離ライナー４であって、以下の順に積層された構成を有する総厚み１１７μｍの積層体Ｆ３（第２中間体Ｍ２）のカール値を測定した結果である。なお、図５に示す結果は、第２光学フィルムＦ２の貼合ローラＲ１への進入角度β＝４３°のときに得られたものである。
　（１）偏光板１０（総厚み６５μｍ）
　　（１－１）保護フィルム１２：ハードコート層（厚み３μｍ）付きシクロオレフィン系保護フィルム（総厚み２９μｍ）
　　（１－２）偏光子１１：ポリビニルアルコール系偏光子（厚み１３μｍ）
　　（１－３）保護フィルム１３：トリアセチルセルロース系保護フィルム（厚み２０μｍ）
　　（１－４）位相差フィルム２：重合性液晶系１／２波長板（厚み１μｍ）及び重合性液晶系１／４波長板（厚み２μｍ）の積層体（総厚み３μｍ）
　（２）粘着剤層３：アクリル系粘着剤層（厚み１４μｍ）
　（３）はく離ライナー４：ポリエチレンテレフタレート製はく離ライナー（厚み３８μｍ）　　 Fig. 5 is a diagram showing an example of the results of measuring the curl value in the TD direction and the curl value in the MD direction of the laminate F3 (second intermediate M2) produced in the release liner lamination step ST3. Specifically, Fig. 5 shows the results of measuring the curl value of the laminate F3 (second intermediate M2) having a total thickness of 117 μm, in which the first optical film F1 is a polarizing plate 10, the second optical film F2 is a release liner 4 with a pressure-sensitive adhesive layer 3, and is laminated in the following order. The results shown in Fig. 5 were obtained when the approach angle β of the second optical film F2 to the lamination roller R1 was 43°.
(1) Polarizing plate 10 (total thickness 65 μm)
(1-1) Protective film 12: Cycloolefin-based protective film (total thickness 29 μm) with a hard coat layer (thickness 3 μm)
(1-2) Polarizer 11: Polyvinyl alcohol polarizer (thickness 13 μm)
(1-3) Protective film 13: Triacetyl cellulose-based protective film (thickness 20 μm)
(1-4) Retardation film 2: a laminate (total thickness 3 μm) of a polymerizable liquid crystal type ½ wavelength plate (thickness 1 μm) and a polymerizable liquid crystal type ¼ wavelength plate (thickness 2 μm)
(2) Pressure-sensitive adhesive layer 3: Acrylic pressure-sensitive adhesive layer (thickness 14 μm)
(3) Release liner 4: polyethylene terephthalate release liner (thickness 38 μm)
　図５に示すように、第１ローラＲ１ａは樹脂ローラであり、この第１ローラＲ１ａに接触する第１フィルムＦ１の貼合ローラＲへの進入角度αに応じて、貼り合わせ後の積層体Ｆ３のＭＤ方向のカール値は略一定であるのに対し、ＴＤ方向のカール値は変化している。
　したがって、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が所定の範囲内となるように、第１ローラＲ１ａに接触する第１光学フィルムＦ１の貼合ローラＲ１への進入角度αを調整すれば、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値を所定の範囲内に制御でき、ひいては、最終的に製造される光学積層体１００のＴＤ方向のカール値を使用上問題とならない程度に抑制可能である。具体的には、図５に示すようなデータを予め採取しておき、このデータに基づき、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が所定の範囲内となるように、第１ローラＲ１ａに接触する第１光学フィルムＦ１の貼合ローラＲ１への進入角度αを調整すれば、調整後には、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値を所定の範囲内に制御可能である。 As shown in Figure 5, the first roller R1a is a resin roller, and the curl value in the MD direction of the laminate F3 after lamination is approximately constant, while the curl value in the TD direction changes, depending on the approach angle α of the first film F1 that contacts this first roller R1a to the lamination roller R.
Therefore, by adjusting the approach angle α of the first optical film F1 in contact with the first roller R1a to the lamination roller R1 so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, the TD curl value of the laminate F3 after lamination can be controlled within a predetermined range, and the TD curl value of the finally manufactured optical laminate 100 can be suppressed to a level that does not cause problems in use. Specifically, data such as that shown in Fig. 5 is collected in advance, and based on this data, the approach angle α of the first optical film F1 in contact with the first roller R1a to the lamination roller R1 is adjusted so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, and after the adjustment, the TD curl value of the laminate F3 after lamination can be controlled within a predetermined range.
　以下、上記のように、貼合ローラＲ１を構成する第１ローラＲ１ａ及び第２ローラＲ１ｂのうち、樹脂ローラである第１ローラＲ１ａに接触する第１光学フィルムＦ１の貼合ローラＲ１への進入角度αに応じて、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が変化する理由について、本発明者らが検討した内容を説明する。 The inventors have investigated the reason why the curl value in the TD direction of the laminate F3 after lamination changes depending on the angle of entry α of the first optical film F1, which contacts the first roller R1a, a resin roller, into the lamination roller R1. The following describes the findings of the inventors.
　図６は、本発明者らが行ったローラたわみ量とＴＤ方向のカール値との関係を調査する試験の概要及び結果の一例を示す図である。図６（ａ）は、本試験において第１ローラＲ１ａに荷重を加えていない状態を模式的に示す正面図（各フィルムの搬送方向（ＭＤ方向）から見た図）である。図６（ｂ）は、本試験において第１ローラＲ１ａに荷重を加えた状態を模式的に示す正面図である。図６（ｃ）は、本試験において、第１ローラＲ１ａの表面（下面）の位置を測定した結果の一例を示す図である。図６（ｄ）は、ローラたわみ量を説明する側面視断面図である。図６（ｅ）は、本試験の結果の一例を示す図である。なお、図６（ａ）、図６（ｂ）及び図６（ｄ）において、フィルムの図示は省略している。
　図６（ａ）に示すように、本発明者らは、第１ローラＲ１ａに荷重を加えていない状態（図示しないフィルムを介して、第１ローラＲ１ａと第２ローラＲ１ｂとが無負荷で接触している状態）で、複数の１次元レーザ距離計２０ａを、第１ローラＲ１ａの回転中心Ｃ１に沿って、第１ローラＲ１ａの表面（下面）に対向するように配置し、各１次元レーザ距離計２０ａから第１ローラＲ１ａの表面（下面）までの距離Ｌａを測定した。１次元レーザ距離計２０ａは、スポット状のレーザ光を照射して、照射位置までの距離を三角測量の原理で測定する装置である。
　同様に、本発明者らは、第１ローラＲ１ａに荷重を加えていない状態で、複数の１次元レーザ距離計２０ｂを、第２ローラＲ１ｂの回転中心Ｃ２に沿って、第２ローラＲ１ｂの表面（上面）に対向するように配置し、各１次元レーザ距離計２０ｂから第２ローラＲ１ｂの表面（上面）までの距離Ｌｂを測定した。１次元レーザ距離計２０ｂは、１次元レーザ距離計２０ａと同じ装置である。
　なお、既知の値である１次元レーザ距離計２０ａと１次元レーザ距離計２０ｂとの離隔距離Ｌ０と、測定した距離Ｌａ及び距離Ｌｂとから、第１ローラＲ１ａの表面（下面）と第２ローラＲ１ｂの表面（上面）との離隔距離Ｌは、Ｌ＝Ｌ０－Ｌａ－Ｌｂによって表されることになる。第１ローラＲ１ａに荷重を加えていない状態では、離隔距離Ｌは、ほぼ一定であると考えられる。 FIG. 6 is a diagram showing an example of the outline and results of a test conducted by the present inventors to investigate the relationship between the amount of roller deflection and the curl value in the TD direction. FIG. 6(a) is a front view (viewed from the conveying direction (MD direction) of each film) showing a state in which no load is applied to the first roller R1a in this test. FIG. 6(b) is a front view showing a state in which a load is applied to the first roller R1a in this test. FIG. 6(c) is a diagram showing an example of the results of measuring the position of the surface (lower surface) of the first roller R1a in this test. FIG. 6(d) is a side view cross-sectional view explaining the amount of roller deflection. FIG. 6(e) is a diagram showing an example of the results of this test. In FIG. 6(a), FIG. 6(b) and FIG. 6(d), the film is omitted from the illustration.
6(a), the inventors arranged multiple one-dimensional laser distance meters 20a along the rotation center C1 of the first roller R1a so as to face the surface (lower surface) of the first roller R1a with no load applied to the first roller R1a (a state in which the first roller R1a and the second roller R1b are in contact with each other without load via a film not shown), and measured the distance La from each one-dimensional laser distance meter 20a to the surface (lower surface) of the first roller R1a. The one-dimensional laser distance meter 20a is a device that irradiates a spot-shaped laser beam and measures the distance to the irradiation position based on the principle of triangulation.
Similarly, the inventors arranged multiple one-dimensional laser distance meters 20b facing the surface (upper surface) of the second roller R1b along the rotation center C2 of the second roller R1b with no load applied to the first roller R1a, and measured the distance Lb from each one-dimensional laser distance meter 20b to the surface (upper surface) of the second roller R1b. The one-dimensional laser distance meter 20b is the same device as the one-dimensional laser distance meter 20a.
From the separation distance L0 between the one-dimensional laser range finder 20a and the one-dimensional laser range finder 20b, which is a known value, and the measured distances La and Lb, the separation distance L between the surface (lower surface) of the first roller R1a and the surface (upper surface) of the second roller R1b is expressed as L = L0 - La - Lb. When no load is applied to the first roller R1a, the separation distance L is considered to be approximately constant.
　次に、図６（ｂ）に示すように、本発明者らは、図６（ａ）に示す状態から、第１ローラＲ１ａに荷重Ｆを加えて、前述と同様に、各１次元レーザ距離計２０ａから第１ローラＲ１ａの表面（下面）までの距離Ｌａ’と、各１次元レーザ距離計２０ｂから第２ローラＲ１ｂの表面（上面）までの距離Ｌｂ’とを測定した。具体的には、第１ローラＲ１ａの回転軸Ｒ１１に加える荷重Ｆを種々の値に変更し、各荷重Ｆを加えた状態で、それぞれ距離Ｌａ’、Ｌｂ’を測定した。
　なお、既知の値である１次元レーザ距離計２０ａと１次元レーザ距離計２０ｂとの離隔距離Ｌ０と、測定した距離Ｌａ’及び距離Ｌｂ’とから、第１ローラＲ１ａの表面（下面）と第２ローラＲ１ｂの表面（上面）との離隔距離Ｌ’は、Ｌ’＝Ｌ０－Ｌａ’－Ｌｂ’によって表されることになる。
　そして、測定した距離Ｌａ、Ｌｂ、Ｌａ’、Ｌｂ’に基づき、ΔＬ＝Ｌ－Ｌ’＝（Ｌ０－Ｌａ－Ｌｂ）－（Ｌ０－Ｌａ’－Ｌｂ’）＝Ｌａ’－Ｌａ＋Ｌｂ’－Ｌｂで算出されるΔＬをローラ変形量として３箇所で算出した。 Next, as shown in Fig. 6(b), the inventors applied a load F to the first roller R1a from the state shown in Fig. 6(a), and measured the distance La' from each one-dimensional laser range finder 20a to the surface (lower surface) of the first roller R1a and the distance Lb' from each one-dimensional laser range finder 20b to the surface (upper surface) of the second roller R1b in the same manner as described above. Specifically, the load F applied to the rotation axis R11 of the first roller R1a was changed to various values, and the distances La' and Lb' were measured with each load F applied.
Furthermore, from the separation distance L0 between the one-dimensional laser rangefinder 20a and the one-dimensional laser rangefinder 20b, which is a known value, and the measured distances La' and Lb', the separation distance L' between the surface (lower surface) of the first roller R1a and the surface (upper surface) of the second roller R1b can be expressed as L' = L0 - La' - Lb'.
Then, based on the measured distances La, Lb, La', and Lb', ΔL was calculated as the roller deformation amount at three locations using the formula ΔL = L-L' = (L0-La-Lb)-(L0-La'-Lb') = La'-La + Lb'-Lb.
　図６（ｂ）に示すように、第１ローラＲ１ａに荷重を加えた状態では、第１ローラＲ１ａの回転中心Ｃ１が下に凸にたわむ。このため、第１ローラＲ１ａの中央部（回転中心Ｃ１方向についての中央部）における距離Ｌａ’よりも、第１ローラＲ１ａの端部（回転中心Ｃ１方向の端部）における距離Ｌａ’の方が大きくなる。
　図６（ｃ）の横軸には、所定の位置を基準値（０ｍｍ）とする第１光学フィルムＦ１のＴＤ方向に相当する第１ローラＲ１ａの回転中心Ｃ１方向の位置をプロットした。また、図６（ｃ）の縦軸には、第１ローラＲ１ａに荷重を加えていない状態で測定した距離Ｌａを基準値（０ｍｍ）として、第１ローラＲ１ａに荷重を加えた状態で測定した距離Ｌａ’の基準値からの変位量を第１ローラＲ１ａの表面（下面）の位置としてプロットした。図６（ｃ）の縦軸が正の値である場合、第１ローラＲ１ａの表面の位置が、基準値よりも１次元レーザ距離計２０ａに近いことを意味する。図６（ｃ）の縦軸が負の値である場合、第１ローラＲ１ａの表面の位置が、基準値よりも１次元レーザ距離計２０ａから遠いことを意味する。図６（ｃ）に示す例からも分かるように、第１ローラＲ１ａに荷重を加えた状態では、荷重が大きくなればなるほど、第１ローラＲ１ａの中央部における距離Ｌａ’よりも、第１ローラＲ１ａの端部における距離Ｌａ’の方が大きくなり、第１ローラＲ１ａの回転中心Ｃ１が下に凸にたわむことになる。 6B, when a load is applied to the first roller R1a, the rotation center C1 of the first roller R1a is bent downward and convex, so that the distance La' at the end of the first roller R1a (the end in the direction of the rotation center C1) is greater than the distance La' at the center of the first roller R1a (the center in the direction of the rotation center C1).
The horizontal axis of FIG. 6(c) plots the position of the first roller R1a in the direction of the rotation center C1, which corresponds to the TD direction of the first optical film F1, with a predetermined position as the reference value (0 mm). The vertical axis of FIG. 6(c) plots the displacement of the distance La' measured with no load applied to the first roller R1a from the reference value (0 mm) as the position of the surface (lower surface) of the first roller R1a. When the vertical axis of FIG. 6(c) is a positive value, it means that the position of the surface of the first roller R1a is closer to the one-dimensional laser distance meter 20a than the reference value. When the vertical axis of FIG. 6(c) is a negative value, it means that the position of the surface of the first roller R1a is farther from the one-dimensional laser distance meter 20a than the reference value. As can be seen from the example shown in Figure 6 (c), when a load is applied to the first roller R1a, the greater the load, the greater the distance La' at the end of the first roller R1a becomes compared to the distance La' at the center of the first roller R1a, and the center of rotation C1 of the first roller R1a bends downward convexly.
　このため、離隔距離Ｌ’は、第１ローラＲ１ａの中央部よりも端部の方が小さくなると考えられる。したがって、ローラ変形量ΔＬは、第１ローラＲ１ａの中央部よりも端部の方が大きくなると考えられる。
　なお、貼合ローラＲ１によって第１光学フィルムＦ１と第２光学フィルムＦ２とを適切に貼り合わせるには、第１ローラＲ１ａに荷重を加える必要があるため、はく離ライナー貼合工程ＳＴ３では、図６（ｂ）に示すような状態となり、ローラ変形量ΔＬが、第１ローラＲ１ａの中央部よりも端部の方が大きくなると考えられる。 For this reason, it is considered that the separation distance L' is smaller at the ends of the first roller R1a than at the center, and therefore the roller deformation amount ΔL is larger at the ends of the first roller R1a than at the center.
In order to properly bond the first optical film F1 and the second optical film F2 together using the lamination roller R1, a load needs to be applied to the first roller R1a. In the release liner lamination process ST3, therefore, the state shown in FIG. 6(b) is reached, and it is considered that the roller deformation amount ΔL is larger at the ends of the first roller R1a than at the center.
　図６（ｄ）に示すように、第１ローラＲ１ａに荷重を加えた状態では、樹脂ローラである第１ローラＲ１ａの第２ローラＲ１ｂに面している側の表面（上面）が変形して潰れることになる。したがって、前述の離隔距離Ｌ’ひいてはローラ変形量ΔＬには、第１ローラＲ１ａの下に凸のたわみだけではなく、この第１ローラＲ１ａの潰れ量（本明細書では、これを「ローラ潰れ量」と称する）も影響することになる。
　図６（ｄ）に示すように、ローラ潰れ量ｈは、第１ローラの回転中心Ｃ１及び第２ローラの回転中心Ｃ２に直交する断面において、第１ローラＲ１ａの潰れている領域に対応する第２ローラＲ１ｂの中心角をθとし、第１ローラＲ１ａの直径を２ｒとすると、幾何学的に、ｈ＝ｒ｛１－ｃｏｓ（θ／２）｝で表される。なお、中心角θは、ｒθで表されるニップ幅を、公知のプレスケールやデジニップを用いて測定することで、算出可能である。
　本発明者らは、ローラ変形量ΔＬからローラ潰れ量ｈの影響を取り除いた値をローラたわみ量εとして算出した。すなわち、ローラたわみ量εをε＝ΔＬ－ｈによって３箇所で算出した。そして、このローラたわみ量εと、はく離ライナー貼合工程ＳＴ３で製造された積層体Ｆ３（第２中間体Ｍ２）のＴＤ方向のカール値との関係を調査した。 6D, when a load is applied to the first roller R1a, the surface (upper surface) of the first roller R1a, which is a resin roller, facing the second roller R1b is deformed and crushed. Therefore, the aforementioned separation distance L' and thus the roller deformation amount ΔL are affected not only by the downward convex deflection of the first roller R1a, but also by the amount of crushing of the first roller R1a (referred to as the "roller crushing amount" in this specification).
6D, the amount of roller crushing h is geometrically expressed as h=r{1-cos(θ/2)}, where θ is the central angle of the second roller R1b corresponding to the crushed area of the first roller R1a in a cross section perpendicular to the rotation center C1 of the first roller and the rotation center C2 of the second roller, and r is the diameter of the first roller R1a. The central angle θ can be calculated by measuring the nip width, which is expressed as rθ, using a known press scale or digitip.
The inventors calculated the roller deflection ε by removing the effect of the roller crush amount h from the roller deformation amount ΔL. That is, the roller deflection ε was calculated at three points by ε = ΔL - h. Then, the relationship between the roller deflection ε and the curl value in the TD direction of the laminate F3 (second intermediate M2) produced in the release liner attachment step ST3 was investigated.
　ローラたわみ量εと、積層体Ｆ３のＴＤ方向のカール値との関係は、第１ローラＲ１ａの直径２ｒ＝１８０ｍｍ、２５０ｍｍ（第２ローラＲ１ｂの直径も同一）の２つについて調査した。第１ローラＲ１ａの直径２ｒ＝１８０ｍｍの場合には、加える荷重Ｆを、圧力換算で、０．１３ＭＰａ、０．２０ＭＰａ、０．２５ＭＰａの３つに変更した。第１ローラＲ１ａの直径２ｒ＝２５０ｍｍの場合には、加える荷重Ｆを、圧力換算で、０．０６ＭＰａ、０．１０ＭＰａ、０．２０ＭＰａ、０．３０ＭＰａの４つに変更した。
　本試験の結果の一例を示す図６（ｅ）の横軸には、３箇所で算出したローラたわみ量εの平均値をプロットした。また、図６（ｅ）の縦軸には、第１ローラＲ１ａの直径２ｒ＝１８０ｍｍの場合には、加える荷重が最も小さな０．１３ＭＰａのときの積層体Ｆ３のＴＤ方向のカール値を基準値とした基準値からの変化量をプロットし、第１ローラＲ１ａの直径２ｒ＝２５０ｍｍの場合には、加える荷重が最も小さな０．０６ＭＰａのときの積層体Ｆ３のＴＤ方向のカール値を基準値とした基準値からの変化量をプロットした。
　図６（ｅ）に示すように、ローラたわみ量εと、積層体Ｆ３のＴＤ方向のカール値とは、比較的良好な相関を有することが分かった。このため、樹脂ローラである第１ローラＲ１ａのたわみが積層体Ｆ３のＴＤ方向のカール値に影響すると考えられる。 The relationship between the roller deflection amount ε and the curl value in the TD direction of the laminate F3 was investigated for two diameters of the first roller R1a, 2r = 180 mm and 250 mm (the diameter of the second roller R1b is also the same). When the diameter of the first roller R1a is 2r = 180 mm, the load F applied was changed to three values, 0.13 MPa, 0.20 MPa, and 0.25 MPa, in terms of pressure. When the diameter of the first roller R1a is 2r = 250 mm, the load F applied was changed to four values, 0.06 MPa, 0.10 MPa, 0.20 MPa, and 0.30 MPa, in terms of pressure.
The horizontal axis of Fig. 6(e), which shows an example of the results of this test, plots the average value of the roller deflection ε calculated at three locations. The vertical axis of Fig. 6(e) plots the amount of change from the reference value, which is the curl value in the TD direction of the laminate F3 when the smallest load of 0.13 MPa is applied, when the diameter of the first roller R1a is 2r = 180 mm, and the amount of change from the reference value, which is the curl value in the TD direction of the laminate F3 when the smallest load of 0.06 MPa is applied, when the diameter of the first roller R1a is 2r = 250 mm.
6(e), it was found that there is a relatively good correlation between the roller deflection ε and the curl value in the TD direction of the laminate F3. For this reason, it is considered that the deflection of the first roller R1a, which is a resin roller, affects the curl value in the TD direction of the laminate F3.
　上記の試験結果を踏まえて、本発明者らは、第１光学フィルムＦ１の表面の位置を測定する試験を行った。
　図７は、本発明者らが行った第１光学フィルムＦ１の表面の位置を測定する試験の概要及び結果の一例を示す図である。図７（ａ）は、本試験の概要を模式的に示す斜視図である。図７（ｂ）は、本試験の概要を模式的に示す側面図である。図７（ｂ）では、２次元距離計の図示を省略している。図７（ｃ）は、図７（ｂ）に示す位置Ｐ１で測定した第１光学フィルムＦ１の表面の位置の一例を示す図である。図７（ｄ）は、図７（ｂ）に示す位置Ｐ２で測定した第１光学フィルムＦ１の表面の位置の一例を示す図である。
　図７（ａ）に示すように、本発明者らは、２個の２次元レーザ距離計３０ａ、３０ｂを、第１光学フィルムＦ１の表面（上面）に対向するように配置し、各２次元レーザ距離計３０ａ、３０ｂを第１光学フィルムＦ１のＴＤ方向に沿って移動させることで、各２次元レーザ距離計３０ａ、３０ｂから第１光学フィルムＦ１の表面（上面）までの距離を測定した。２次元レーザ距離計３０ａ、３０ｂは、線状のレーザ光を照射して、照射位置までの距離を三角測量の原理で測定する装置である。本試験では、線状のレーザ光が延びる方向が第１光学フィルムＦ１のＴＤ方向に沿うように、２次元レーザ距離計３０ａ、３０ｂの向きを調整して配置した。本試験で用いた各２次元レーザ距離計３０ａ、３０ｂの測定範囲（第１光学フィルムＦ１のＴＤ方向の測定範囲）はそれぞれ約２１０ｍｍであり、第１光学フィルムのＴＤ方向の寸法よりも小さいため、各２次元レーザ距離計３０ａ、３０ｂを第１光学フィルムＦ１のＴＤ方向に沿ってそれぞれ第１光学フィルムＦ１のＴＤ方向に移動させることで、第１光学フィルムＦ１の表面までの距離を第１光学フィルムＦ１のＴＤ方向全体に亘って測定した。 Based on the above test results, the present inventors conducted a test to measure the position on the surface of the first optical film F1.
Fig. 7 is a diagram showing an example of the outline and results of a test conducted by the present inventors to measure the surface position of the first optical film F1. Fig. 7(a) is a perspective view that shows a schematic outline of the test. Fig. 7(b) is a side view that shows a schematic outline of the test. In Fig. 7(b), the illustration of the two-dimensional distance meter is omitted. Fig. 7(c) is a diagram showing an example of the surface position of the first optical film F1 measured at position P1 shown in Fig. 7(b). Fig. 7(d) is a diagram showing an example of the surface position of the first optical film F1 measured at position P2 shown in Fig. 7(b).
As shown in Fig. 7(a), the inventors arranged two two-dimensional laser distance meters 30a and 30b so as to face the surface (upper surface) of the first optical film F1, and moved each of the two-dimensional laser distance meters 30a and 30b along the TD direction of the first optical film F1 to measure the distance from each of the two-dimensional laser distance meters 30a and 30b to the surface (upper surface) of the first optical film F1. The two-dimensional laser distance meters 30a and 30b are devices that irradiate a linear laser beam and measure the distance to the irradiation position based on the principle of triangulation. In this test, the orientation of the two-dimensional laser distance meters 30a and 30b was adjusted and arranged so that the direction in which the linear laser beam extends is along the TD direction of the first optical film F1. The measurement range of each of the two- dimensional laser rangefinders 30a, 30b used in this test (measurement range in the TD direction of the first optical film F1) was approximately 210 mm, which is smaller than the dimension of the first optical film in the TD direction.Therefore, each of the two- dimensional laser rangefinders 30a, 30b was moved in the TD direction of the first optical film F1 along the TD direction of the first optical film F1, thereby measuring the distance to the surface of the first optical film F1 over the entire TD direction of the first optical film F1.
　２次元レーザ距離計３０ａ、３０ｂは、第１光学フィルムＦ１が第１ローラＲ１ａに接触する直前の位置（図７（ｂ）に示す位置Ｐ１）での第１光学フィルムＦ１の表面に対向する位置と、第１光学フィルムＦ１が第１ローラＲ１ａに接触した後の位置（図７（ｂ）に示す位置Ｐ２）での第１光学フィルムＦ１の表面に対向する位置との双方にそれぞれ配置し、各位置Ｐ１、Ｐ２で第１光学フィルムＦ１の表面までの距離を測定した。各位置Ｐ１、Ｐ２で第１光学フィルムＦ１の表面までの距離は、第１ローラＲ１ａに加える荷重Ｆを、圧力換算で、０．００ＭＰａ、０．１３ＭＰａ、０．２０ＭＰａ、０．３０ＭＰａの４つに変更し、各荷重Ｆに対して測定した。
　本試験の結果の一例を示す図７（ｃ）及び図７（ｄ）の横軸には、所定の位置を基準値（０ｍｍ）とする第１光学フィルムＦ１のＴＤ方向の位置をプロットした。また、図７（ｃ）及び図７（ｄ）の縦軸には、所定の距離を基準値（０ｍｍ）として、測定した距離の基準値からの変位量を第１光学フィルムＦ１の表面の位置としてプロットした。図７（ｃ）及び図７（ｄ）の縦軸が正の値である場合、第１光学フィルムＦ１の表面の位置が、所定の基準値よりも２次元レーザ距離計３０ａ、３０ｂに近いことを意味する。図７（ｃ）及び図７（ｄ）の縦軸が負の値である場合、第１光学フィルムＦ１の表面の位置が、所定の基準値よりも２次元レーザ距離計３０ａ、３０ｂから遠いことを意味する。 The two-dimensional laser distance meters 30a and 30b were placed at positions facing the surface of the first optical film F1 at a position (position P1 shown in FIG. 7(b)) immediately before the first optical film F1 contacted the first roller R1a, and at a position (position P2 shown in FIG. 7(b)) after the first optical film F1 contacted the first roller R1a, and the distance to the surface of the first optical film F1 was measured at each of the positions P1 and P2. The load F applied to the first roller R1a was changed to four loads, 0.00 MPa, 0.13 MPa, 0.20 MPa, and 0.30 MPa in terms of pressure, and the distance to the surface of the first optical film F1 at each of the positions P1 and P2 was measured for each load F.
7(c) and 7(d), which show an example of the results of this test, the horizontal axis plots the TD position of the first optical film F1 with a predetermined position as the reference value (0 mm). Also, the vertical axis of FIG. 7(c) and FIG. 7(d) plots the displacement of the measured distance from the reference value as the surface position of the first optical film F1 with a predetermined distance as the reference value (0 mm). When the vertical axis of FIG. 7(c) and FIG. 7(d) is a positive value, it means that the surface position of the first optical film F1 is closer to the two-dimensional laser distance meters 30a and 30b than the predetermined reference value. When the vertical axis of FIG. 7(c) and FIG. 7(d) is a negative value, it means that the surface position of the first optical film F1 is farther from the two-dimensional laser distance meters 30a and 30b than the predetermined reference value.
　図７（ｃ）に示すように、第１光学フィルムＦ１が第１ローラＲ１ａに接触する直前の位置Ｐ１では、第１ローラＲ１ａに荷重Ｆを加えた場合、第１光学フィルムＦ１は下に凸にたるみ、荷重Ｆが大きくなればなるほど、たるみの程度が大きくなることが分かった。
　一方、第１光学フィルムＦ１が第１ローラＲ１ａに接触した後の位置Ｐ２では、第１ローラＲ１ａに荷重Ｆを加えた場合、第１光学フィルムＦ１は上に凸にたるみ、荷重Ｆが大きくなればなるほど、たるみの程度が大きくなることが分かった。 As shown in Figure 7 (c), when a load F is applied to the first roller R1a at position P1 immediately before the first optical film F1 contacts the first roller R1a, the first optical film F1 sags convexly downward, and it was found that the greater the load F, the greater the degree of sagging.
On the other hand, it was found that at position P2 after the first optical film F1 comes into contact with the first roller R1a, when a load F is applied to the first roller R1a, the first optical film F1 sags convexly upward, and the greater the load F, the greater the degree of sagging.
　図８は、以上の結果に基づき、本発明者らが推測した、樹脂ローラである第１ローラＲ１ａに接触する第１光学フィルムＦ１の貼合ローラＲ１への進入角度αに応じて、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が変化する理由を模式的に説明する説明図である。
　図６を参照して前述したように、樹脂ローラである第１ローラＲ１ａに荷重Ｆを付加すると、第１ローラＲ１ａの回転中心Ｃ１が下に凸にたわむ。このため、第１光学フィルムＦ１に接触する第１ローラＲ１ａの直径が、第１ローラ１ａの端部よりも中央部の方が大きくなっている場合と同様の状態となり、第１ローラ１ａの中央部の方が端部に比べて、第１光学フィルムＦ１が第１ローラ１ａと接触し始める点から、第１光学フィルムＦ１が第２光学フィルムＦ２と貼り合わせられる点までの距離が長くなる。この結果、図８に示すように、第１ローラＲ１ａに接触する直前の第１光学フィルムＦ１を中央部に向けて流そうとする力ＦＣが作用することになる。これにより、図７（ｃ）を参照して前述したように、第１光学フィルムＦ１は下に凸にたるむことになる。
　一方、図８に示すように、第１光学フィルムＦ１が第１ローラＲ１ａに接触した後（図８において、ドット状のハッチングを施した部分）には、第１光学フィルムＦ１の下側に第１ローラＲ１ａが存在するため、第１光学フィルムＦ１は下に凸にたるむことができず、第１ローラＲ１ａに接触する直前のたるみ量に応じて、第１光学フィルムＦ１が上に凸に反転することになる。
　そして、第１光学フィルムＦ１が上に凸に反転したまま、第２光学フィルムＦ２と貼り合わせられるため、上に凸に反転した第１光学フィルムＦ１の形状が、図６（ｄ）を参照して前述したように、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値に影響を及ぼすと考えられる。そして、進入角度αが大きくなるほど、第１ローラＲ１ａに接触する第１光学フィルムＦ１の長さが大きくなるため、第１ローラＲ１ａに接触する直前の第１光学フィルムＦ１を中央部に向けて流そうとする力ＦＣも大きくなり、第１ローラＲ１ａに接触する直前の第１光学フィルムＦ１のたるみ量、ひいては、第１ローラＲ１ａに接触した後の第１光学フィルムＦ１の反転量が大きくなる結果、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が変化するのだと考えられる。なお、第１ローラＲ１ａに接触する直前の第１光学フィルムＦ１のたるみ量が大きくなりすぎると、第１光学フィルムＦ１と第２光学フィルムＦ２との間に隙間が生じて上手く貼り合わせられなかったり、積層体Ｆ３に皺や揉まれが発生するおそれがある。 FIG. 8 is an explanatory diagram that illustrates, as inferred by the inventors based on the above results, why the curl value in the TD direction of the laminate F3 after lamination changes depending on the approach angle α of the first optical film F1, which is in contact with the first roller R1a, which is a resin roller, into the lamination roller R1.
As described above with reference to FIG. 6, when a load F is applied to the first roller R1a, which is a resin roller, the center of rotation C1 of the first roller R1a is bent downwardly convexly. This results in a state similar to that in the case where the diameter of the first roller R1a in contact with the first optical film F1 is larger at the center than at the ends of the first roller 1a, and the distance from the point where the first optical film F1 starts to contact the first roller 1a to the point where the first optical film F1 is bonded to the second optical film F2 is longer at the center of the first roller 1a than at the ends. As a result, as shown in FIG. 8, a force FC acts on the first optical film F1 immediately before it comes into contact with the first roller R1a, which tends to move it toward the center. This causes the first optical film F1 to sag downwardly convexly, as described above with reference to FIG. 7(c).
On the other hand, as shown in Figure 8, after the first optical film F1 comes into contact with the first roller R1a (the area hatched in Figure 8), the first roller R1a is present below the first optical film F1, and therefore the first optical film F1 cannot sag downwardly and is instead inverted to become upwardly convex depending on the amount of sagging just before coming into contact with the first roller R1a.
Since the first optical film F1 is laminated to the second optical film F2 while remaining inverted upwardly convex, it is considered that the shape of the first optical film F1 inverted upwardly convex affects the curl value in the TD direction of the laminate F3 after lamination, as described above with reference to Fig. 6(d). As the approach angle α increases, the length of the first optical film F1 in contact with the first roller R1a increases, and therefore the force FC that tries to move the first optical film F1 toward the center immediately before contacting the first roller R1a also increases, and the amount of slack in the first optical film F1 immediately before contacting the first roller R1a, and therefore the amount of reversal of the first optical film F1 after contacting the first roller R1a, increases. As a result, it is considered that the curl value in the TD direction of the laminate F3 after lamination changes. Furthermore, if the amount of slack in the first optical film F1 immediately before contacting the first roller R1a becomes too large, a gap may occur between the first optical film F1 and the second optical film F2, preventing them from being properly bonded together, or wrinkles or crumples may occur in the laminate F3.
　図９は、はく離ライナー貼合工程ＳＴ３で製造された積層体Ｆ３（第２中間体Ｍ２）のＴＤ方向のカール値及びＭＤ方向のカール値を測定した結果の他の例を示す図である。具体的には、図９は、第１光学フィルムＦ１が粘着剤層３（厚み１４μｍ）付き偏光板１０であり、総厚みが１３１μｍである点を除いて、図５に示す例と同様の構成を有する積層体Ｆ３（第２中間体Ｍ２）のカール値を測定した結果である。なお、図９に示す結果は、第２光学フィルムＦ２の貼合ローラＲ１への進入角度β＝４３°のときに得られたものである。
　図９に示すように、図５に示す結果と同様に、第１フィルムＦ１の貼合ローラＲへの進入角度αに応じて、貼り合わせ後の積層体Ｆ３のＭＤ方向のカール値は略一定であるのに対し、ＴＤ方向のカール値は変化している。
　したがって、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が所定の範囲内となるように、第１ローラＲ１ａに接触する第１光学フィルムＦ１の貼合ローラＲ１への進入角度αを調整すれば、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値を所定の範囲内に制御でき、ひいては、最終的に製造される光学積層体１００のＴＤ方向のカール値を使用上問題とならない程度に抑制可能である。具体的には、図９に示すようなデータを予め採取しておき、このデータに基づき、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が所定の範囲内となるように、第１ローラＲ１ａに接触する第１光学フィルムＦ１の貼合ローラＲ１への進入角度αを調整すれば、調整後には、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値を所定の範囲内に制御可能である。 Fig. 9 is a diagram showing another example of the results of measuring the curl value in the TD direction and the curl value in the MD direction of the laminate F3 (second intermediate M2) produced in the release liner lamination step ST3. Specifically, Fig. 9 shows the results of measuring the curl value of the laminate F3 (second intermediate M2) having the same configuration as the example shown in Fig. 5, except that the first optical film F1 is a polarizing plate 10 with a pressure-sensitive adhesive layer 3 (thickness 14 μm) and has a total thickness of 131 μm. The results shown in Fig. 9 were obtained when the approach angle β of the second optical film F2 to the lamination roller R1 was 43°.
As shown in Figure 9, similar to the results shown in Figure 5, the curl value in the MD direction of the laminate F3 after lamination is approximately constant, while the curl value in the TD direction changes depending on the approach angle α of the first film F1 to the lamination roller R.
Therefore, by adjusting the approach angle α of the first optical film F1 in contact with the first roller R1a to the lamination roller R1 so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, the TD curl value of the laminate F3 after lamination can be controlled within a predetermined range, and the TD curl value of the finally manufactured optical laminate 100 can be suppressed to a level that does not cause problems in use. Specifically, data such as that shown in Fig. 9 is collected in advance, and based on this data, the approach angle α of the first optical film F1 in contact with the first roller R1a to the lamination roller R1 is adjusted so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, and after the adjustment, the TD curl value of the laminate F3 after lamination can be controlled within a predetermined range.
　［検査工程ＳＴ４］
　検査工程ＳＴ４では、長尺帯状のはく離ライナー４を粘着剤層３からはく離（はく離ライナー４と偏光板１０との間に介在する粘着剤層３を偏光板１０側に残したまま、はく離ライナー４のみをはく離）した後、偏光板１０（第１中間体Ｍ１）を検査する。偏光板１０の検査方法としては、詳細な説明は割愛するが、透過検査、クロスニコル検査、反射検査などの公知の検査方法が挙げられる。検査工程ＳＴ４では、偏光板１０を検査した後、はく離したはく離ライナー４を再び偏光板１０に貼り合わせる（はく離したはく離ライナー４とは異なる新しいはく離ライナー４を偏光板１０に貼り合わせることを含む）ことで、元の第２中間体Ｍ２の状態に戻す。 [Inspection process ST4]
In the inspection process ST4, the long strip-shaped release liner 4 is peeled off from the adhesive layer 3 (only the release liner 4 is peeled off while the adhesive layer 3 interposed between the release liner 4 and the polarizing plate 10 is left on the polarizing plate 10 side), and then the polarizing plate 10 (first intermediate M1) is inspected. Although detailed explanations are omitted, known inspection methods such as a transmission inspection, a crossed Nicol inspection, and a reflection inspection can be mentioned as the inspection method for the polarizing plate 10. In the inspection process ST4, after inspecting the polarizing plate 10, the peeled release liner 4 is bonded again to the polarizing plate 10 (including bonding a new release liner 4 different from the peeled release liner 4 to the polarizing plate 10) to return it to the original state of the second intermediate M2.
　図１０は、検査工程ＳＴ４において、はく離ライナー４を再び偏光板１０に貼り合わせる装置の概略構成例を模式的に示す側面図（各フィルムの搬送方向（ＭＤ方向）に直交する水平方向（ＴＤ方向）から見た図）である。図１０に示す矢符は、各フィルムの搬送方向を意味する。
　前述のように、本発明では、貼合ローラによって貼り合わせる一方のフィルムを第１光学フィルムＦ１とし、他方のフィルムを第２光学フィルムＦ２としている。検査工程ＳＴ４では、第１光学フィルムＦ１は、検査後の第１中間体Ｍ１（偏光板１０及び粘着剤層３）であり、第２光学フィルムＦ２は、はく離ライナー４（はく離したはく離ライナー４、又は、新しいはく離ライナー４）である。この第１光学フィルムＦ１と第２光学フィルムＦ２とが、粘着剤層３を介して、貼合ローラＲ５によって貼り合わされ、第１光学フィルムＦ１と第２光学フィルムＦ２との積層体Ｆ３が製造される。検査工程ＳＴ４では、積層体Ｆ３は、第２中間体Ｍ２である。 10 is a side view (as viewed from the horizontal direction (TD direction) perpendicular to the conveying direction (MD direction) of each film) showing a schematic configuration example of an apparatus for bonding the release liner 4 again to the polarizing plate 10 in the inspection process ST4. The arrows shown in FIG. 10 indicate the conveying direction of each film.
As described above, in the present invention, one of the films bonded by the lamination roller is the first optical film F1, and the other film is the second optical film F2. In the inspection process ST4, the first optical film F1 is the first intermediate M1 (polarizing plate 10 and adhesive layer 3) after inspection, and the second optical film F2 is the release liner 4 (the peeled release liner 4 or the new release liner 4). The first optical film F1 and the second optical film F2 are bonded together by the lamination roller R5 via the adhesive layer 3 to produce a laminate F3 of the first optical film F1 and the second optical film F2. In the inspection process ST4, the laminate F3 is the second intermediate M2.
　具体的には、図１０に示すように、貼合ローラＲ５の入側（貼合ローラＲ５に対して、第１光学フィルムＦ１の搬送方向上流側であり、図１０に示す例では、貼合ローラＲ５の上側）に第１光学フィルムＦ１に接触する第１搬送ローラＲ６が配置され、第１搬送ローラＲ６によって、第１光学フィルムＦ１が貼合ローラＲ５に搬送される。同様に、貼合ローラＲ５の入側（貼合ローラＲ５に対して、第２光学フィルムＦ２の搬送方向上流側であり、図１０に示す例では、貼合ローラＲ５の上側）に第２光学フィルムＦ２に接触する第２搬送ローラＲ７が配置され、第２搬送ローラＲ７によって、第２光学フィルムＦ２が貼合ローラＲ５に搬送される。
　第１搬送ローラＲ６は、貼合ローラＲ５に対する位置（本実施形態では、水平方向の位置）を調整可能になっている。図１０に示す例では、第１搬送ローラＲ６は、実線で示す最右部の位置から、破線で示す位置を経て、一点鎖線で示す最左部の位置に移動可能である。例えば、第１搬送ローラＲ６の回転軸が軸受を介して一軸アクチュエータに取り付けられ、この一軸アクチュエータを駆動することで、第１搬送ローラＲ６の位置を調整可能にする構成を採用可能である。
　一方、第２搬送ローラＲ７は、所定の位置に固定されている。 Specifically, as shown in Fig. 10, a first transport roller R6 in contact with the first optical film F1 is disposed on the entry side of the lamination roller R5 (upstream side in the transport direction of the first optical film F1 with respect to the lamination roller R5, and above the lamination roller R5 in the example shown in Fig. 10), and the first optical film F1 is transported to the lamination roller R5 by the first transport roller R6. Similarly, a second transport roller R7 in contact with the second optical film F2 is disposed on the entry side of the lamination roller R5 (upstream side in the transport direction of the second optical film F2 with respect to the lamination roller R5, and above the lamination roller R5 in the example shown in Fig. 10), and the second transport roller R7 transports the second optical film F2 to the lamination roller R5.
The position of the first conveying roller R6 relative to the lamination roller R5 (in this embodiment, the horizontal position) is adjustable. In the example shown in Fig. 10, the first conveying roller R6 can move from the rightmost position shown by the solid line, through the position shown by the dashed line, to the leftmost position shown by the dashed line. For example, a configuration can be adopted in which the rotation shaft of the first conveying roller R6 is attached to a single-axis actuator via a bearing, and the position of the first conveying roller R6 can be adjusted by driving the single-axis actuator.
On the other hand, the second transport roller R7 is fixed at a predetermined position.
　貼合ローラＲ５は、第１ローラＲ５ａと、第１ローラＲ５ａに対向（図１０に示す例では水平方向に対向）して配置された第２ローラＲ５ｂと、から構成されている。
　第１ローラＲ５ａは、第１光学フィルムＦ１に接触して、第１ローラＲ５ａと第２ローラＲ５ｂとの間に第１光学フィルムＦ１を搬送するローラである。第１ローラＲ５ａは、その表面が樹脂（本実施形態では、シリコンゴム）から形成された樹脂ローラである。
　第２ローラＲ５ｂは、第２光学フィルムＦ２に接触して、第１ローラＲ５ａと第２ローラＲ５ｂとの間に第２光学フィルムＦ２を搬送するローラである。第２ローラＲ５ｂは、その表面が金属（本実施形態では、鉄）から形成された金属ローラである。
　第１光学フィルムＦ１及び第２光学フィルムＦ２が第１ローラＲ５ａと第２ローラＲ５ｂとの間に進入することで、第１光学フィルムＦ１と第２光学フィルムＦ２とが貼り合わせられ、第１光学フィルムＦ１と第２光学フィルムＦ２との積層体Ｆ３が製造される。積層体Ｆ３は、搬送ローラＲ８によって搬送され、巻取ローラ（図示せず）で巻き取られる。 The lamination roller R5 is composed of a first roller R5a and a second roller R5b disposed opposite the first roller R5a (opposing in the horizontal direction in the example shown in FIG. 10).
The first roller R5a is a roller that comes into contact with the first optical film F1 and transports the first optical film F1 between the first roller R5a and the second roller R5b. The first roller R5a is a resin roller whose surface is made of resin (silicone rubber in this embodiment).
The second roller R5b is a roller that comes into contact with the second optical film F2 and transports the second optical film F2 between the first roller R5a and the second roller R5b. The second roller R5b is a metal roller whose surface is made of metal (iron in this embodiment).
The first optical film F1 and the second optical film F2 enter between the first roller R5a and the second roller R5b, whereby the first optical film F1 and the second optical film F2 are bonded together to produce a laminate F3 of the first optical film F1 and the second optical film F2. The laminate F3 is transported by the transport roller R8 and taken up by a take-up roller (not shown).
　検査工程ＳＴ４では、積層体Ｆ３のＴＤ方向のカール値が所定の範囲内となるように、第１光学フィルムＦ１の貼合ローラＲ５への進入角度αが調整される。進入角度αの意味は、図３（ｂ）を参照して説明したものと同様である。具体的には、第１搬送ローラＲ６の貼合ローラＲ５に対する位置を水平方向に調整することで、進入角度αが調整される。図１０に実線で示す最右部の位置に第１搬送ローラＲ６が位置するときに、進入角度αは最も小さい０°となり、一点鎖線で示す最左部の位置に第１搬送ローラＲ６が位置するときに、進入角度αは最も大きな値となる。 In the inspection process ST4, the approach angle α of the first optical film F1 to the lamination roller R5 is adjusted so that the TD curl value of the laminate F3 falls within a predetermined range. The meaning of the approach angle α is the same as that explained with reference to FIG. 3(b). Specifically, the approach angle α is adjusted by adjusting the position of the first transport roller R6 relative to the lamination roller R5 in the horizontal direction. When the first transport roller R6 is located at the rightmost position shown by the solid line in FIG. 10, the approach angle α is at its smallest, 0°, and when the first transport roller R6 is located at the leftmost position shown by the dashed line, the approach angle α is at its largest value.
　図１１は、検査工程ＳＴ４で製造された積層体Ｆ３（第２中間体Ｍ２）のＴＤ方向のカール値及びＭＤ方向のカール値を測定した結果の一例を示す図である。具体的には、図１１は、図９に示す例と同様の構成を有する積層体Ｆ３（第２中間体Ｍ２）のカール値を測定した結果である。なお、図１１に示す結果は、第２光学フィルムＦ２の貼合ローラＲ１への進入角度β＝４３　°のときに得られたものである。
　図１１に示すように、図５や図９に示す結果と同様に、第１フィルムＦ１の貼合ローラＲへの進入角度αに応じて、貼り合わせ後の積層体Ｆ３のＭＤ方向のカール値は略一定であるのに対し、ＴＤ方向のカール値は変化している。
　したがって、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が所定の範囲内となるように、第１ローラＲ５ａに接触する第１光学フィルムＦ１の貼合ローラＲ５への進入角度αを調整すれば、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値を所定の範囲内に制御でき、ひいては、最終的に製造される光学積層体１００のＴＤ方向のカール値を使用上問題とならない程度に抑制可能である。具体的には、図１１に示すようなデータを予め採取しておき、このデータに基づき、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が所定の範囲内となるように、第１ローラＲ５ａに接触する第１光学フィルムＦ１の貼合ローラＲ５への進入角度αを調整すれば、調整後には、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値を所定の範囲内に制御可能である。 Fig. 11 is a diagram showing an example of the results of measuring the curl value in the TD direction and the curl value in the MD direction of the laminate F3 (second intermediate M2) produced in the inspection process ST4. Specifically, Fig. 11 shows the results of measuring the curl value of the laminate F3 (second intermediate M2) having the same configuration as the example shown in Fig. 9. The results shown in Fig. 11 were obtained when the approach angle β of the second optical film F2 to the lamination roller R1 was 43°.
As shown in Figure 11, similar to the results shown in Figures 5 and 9, the curl value in the MD direction of the laminate F3 after lamination is approximately constant, while the curl value in the TD direction changes, depending on the approach angle α of the first film F1 to the lamination roller R.
Therefore, by adjusting the approach angle α of the first optical film F1 in contact with the first roller R5a to the lamination roller R5 so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, the TD curl value of the laminate F3 after lamination can be controlled within a predetermined range, and the TD curl value of the finally manufactured optical laminate 100 can be suppressed to a level that does not cause problems in use. Specifically, data such as that shown in Fig. 11 is collected in advance, and based on this data, the approach angle α of the first optical film F1 in contact with the first roller R5a to the lamination roller R5 is adjusted so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, and after the adjustment, the TD curl value of the laminate F3 after lamination can be controlled within a predetermined range.
　［表面保護フィルム貼合工程ＳＴ５］
　表面保護フィルム貼合工程ＳＴ５では、長尺帯状の第２中間体Ｍ２に長尺帯状の表面保護フィルム５を貼り合わせる。具体的には、第２中間体Ｍ２を構成する偏光板１０のはく離ライナー４が貼り合わせられた側とは反対側の面に、長尺帯状の表面保護フィルム５が貼り合わせられる。これにより、長尺帯状の光学積層体１００が製造される。 [Surface protection film attachment step ST5]
In the surface protection film bonding step ST5, a long strip-shaped surface protection film 5 is bonded to the long strip-shaped second intermediate M2. Specifically, the long strip-shaped surface protection film 5 is bonded to the surface of the polarizing plate 10 constituting the second intermediate M2 opposite to the surface to which the release liner 4 is bonded. In this way, a long strip-shaped optical laminate 100 is manufactured.
　図１２は、表面保護フィルム貼合工程ＳＴ５を実行する装置の概略構成例を模式的に示す側面図（各フィルムの搬送方向（ＭＤ方向）に直交する水平方向（ＴＤ方向）から見た図）である。図１２（ａ）は第１例を、図１２（ｂ）は第２例を示す。図１２に示す矢符は、各フィルムの搬送方向を意味する。
　前述のように、本発明では、貼合ローラによって貼り合わせる一方のフィルムを第１光学フィルムＦ１とし、他方のフィルムを第２光学フィルムＦ２としている。表面保護フィルム貼合工程ＳＴ５では、第１光学フィルムＦ１は、第２中間体Ｍ２であり、第２光学フィルムＦ２は、表面保護フィルム５である。この第１光学フィルムＦ１と第２光学フィルムＦ２とが、表面保護フィルム５の粘着剤層を介して、貼合ローラＲ９によって貼り合わされ、第１光学フィルムＦ１と第２光学フィルムＦ２との積層体Ｆ３が製造される。表面保護フィルム貼合工程ＳＴ５では、積層体Ｆ３は、光学積層体１００である。 FIG. 12 is a side view (as viewed from a horizontal direction (TD direction) perpendicular to the conveying direction (MD direction) of each film) showing a schematic configuration example of an apparatus that performs the surface protective film bonding process ST5. FIG. 12(a) shows a first example, and FIG. 12(b) shows a second example. The arrows shown in FIG. 12 indicate the conveying direction of each film.
As described above, in the present invention, one of the films bonded by the bonding roller is the first optical film F1, and the other film is the second optical film F2. In the surface protective film bonding step ST5, the first optical film F1 is the second intermediate M2, and the second optical film F2 is the surface protective film 5. The first optical film F1 and the second optical film F2 are bonded together by the bonding roller R9 via the adhesive layer of the surface protective film 5, to produce a laminate F3 of the first optical film F1 and the second optical film F2. In the surface protective film bonding step ST5, the laminate F3 is the optical laminate 100.
　具体的には、図１２に示すように、第１例及び第２例の何れについても、貼合ローラＲ９の入側（貼合ローラＲ９に対して、第１光学フィルムＦ１の搬送方向上流側であり、図１２に示す例では、貼合ローラＲ９の左側）に第１光学フィルムＦ１に接触する第１搬送ローラＲ１０が配置され、第１搬送ローラＲ１０によって、第１光学フィルムＦ１が貼合ローラＲ９に搬送される。同様に、貼合ローラＲ９の入側（貼合ローラＲ９に対して、第２光学フィルムＦ２の搬送方向上流側であり、図１２に示す例では、貼合ローラＲ９の左側）に第２光学フィルムＦ２に接触する第２搬送ローラＲ１１が配置され、第２搬送ローラＲ１１によって、第２光学フィルムＦ２が貼合ローラＲ９に搬送される。
　そして、図１２（ａ）に示す第１例では、第１搬送ローラＲ１０は、貼合ローラＲ９に対する位置（本実施形態では、上下方向の位置）を調整可能になっている。図１２（ａ）に示す第１例では、第１搬送ローラＲ１０は、実線で示す最上部の位置から、破線で示す位置を経て、一点鎖線で示す最下部の位置に移動可能である。例えば、第１搬送ローラＲ１０の回転軸が軸受を介して一軸アクチュエータに取り付けられ、この一軸アクチュエータを駆動することで、第１搬送ローラＲ１０の位置を調整可能にする構成を採用可能である。一方、第２搬送ローラＲ１１は、所定の位置に固定されている。
　一方、図１２（ｂ）に示す第２例では、第２搬送ローラＲ１１は、貼合ローラＲ９に対する位置（本実施形態では、上下方向の位置）を調整可能になっている。図１２（ｂ）に示す第２例では、第２搬送ローラＲ１１は、実線で示す最下部の位置から、破線で示す位置を経て、一点鎖線で示す最上部の位置に移動可能である。例えば、第２搬送ローラＲ１１の回転軸が軸受を介して一軸アクチュエータに取り付けられ、この一軸アクチュエータを駆動することで、第２搬送ローラＲ１１の位置を調整可能にする構成を採用可能である。一方、第１搬送ローラＲ１０は、所定の位置に固定されている。 Specifically, as shown in Fig. 12, in both the first and second examples, a first transport roller R10 that contacts the first optical film F1 is disposed on the entry side of the lamination roller R9 (upstream of the transport direction of the first optical film F1 with respect to the lamination roller R9, and to the left of the lamination roller R9 in the example shown in Fig. 12), and the first optical film F1 is transported to the lamination roller R9 by the first transport roller R10. Similarly, a second transport roller R11 that contacts the second optical film F2 is disposed on the entry side of the lamination roller R9 (upstream of the transport direction of the second optical film F2 with respect to the lamination roller R9, and to the left of the lamination roller R9 in the example shown in Fig. 12), and the second optical film F2 is transported to the lamination roller R9 by the second transport roller R11.
In the first example shown in FIG. 12(a), the position of the first conveying roller R10 relative to the lamination roller R9 (in the present embodiment, the position in the vertical direction) can be adjusted. In the first example shown in FIG. 12(a), the first conveying roller R10 can move from the top position shown by the solid line, through the position shown by the dashed line, to the bottom position shown by the dashed line. For example, a configuration can be adopted in which the rotation shaft of the first conveying roller R10 is attached to a single-axis actuator via a bearing, and the position of the first conveying roller R10 can be adjusted by driving this single-axis actuator. On the other hand, the second conveying roller R11 is fixed at a predetermined position.
On the other hand, in the second example shown in FIG. 12(b), the position of the second conveying roller R11 relative to the laminating roller R9 (in the present embodiment, the position in the vertical direction) can be adjusted. In the second example shown in FIG. 12(b), the second conveying roller R11 can move from the bottom position shown by the solid line, through the position shown by the dashed line, to the top position shown by the dashed line. For example, a configuration can be adopted in which the rotation shaft of the second conveying roller R11 is attached to a single-axis actuator via a bearing, and the position of the second conveying roller R11 can be adjusted by driving this single-axis actuator. On the other hand, the first conveying roller R10 is fixed at a predetermined position.
　第１例及び第２例の何れについても、貼合ローラＲ９は、第１ローラＲ９ａと、第１ローラＲ９ａに対向（図１２に示す例では上下方向に対向）して配置された第２ローラＲ９ｂと、から構成されている。
　第１例及び第２例の第１ローラＲ９ａは、第１光学フィルムＦ１に接触して、第１ローラＲ９ａと第２ローラＲ９ｂとの間に第１光学フィルムＦ１を搬送するローラである。第１ローラＲ９ａは、その表面が樹脂（本実施形態では、シリコンゴム）から形成された樹脂ローラである。
　第１例及び第２例の第２ローラＲ９ｂは、第２光学フィルムＦ２に接触して、第１ローラＲ９ａと第２ローラＲ９ｂとの間に第２光学フィルムＦ２を搬送するローラである。第２ローラＲ９ｂも、第１ローラＲ９ａと同様に、その表面が樹脂（本実施形態では、シリコンゴム）から形成された樹脂ローラである。
　第１光学フィルムＦ１及び第２光学フィルムＦ２が第１ローラＲ９ａと第２ローラＲ９ｂとの間に進入することで、第１光学フィルムＦ１と第２光学フィルムＦ２とが貼り合わせられ、第１光学フィルムＦ１と第２光学フィルムＦ２との積層体Ｆ３が製造される。積層体Ｆ３は、搬送ローラＲ１２によって搬送され、巻取ローラ（図示せず）で巻き取られる。 In both the first and second examples, the lamination roller R9 is composed of a first roller R9a and a second roller R9b arranged opposite the first roller R9a (opposing in the vertical direction in the example shown in Figure 12).
The first roller R9a in the first and second examples is a roller that comes into contact with the first optical film F1 and transports the first optical film F1 between the first roller R9a and the second roller R9b. The first roller R9a is a resin roller whose surface is made of resin (silicone rubber in this embodiment).
The second roller R9b in the first and second examples is a roller that comes into contact with the second optical film F2 and transports the second optical film F2 between the first roller R9a and the second roller R9b. Like the first roller R9a, the second roller R9b is also a resin roller whose surface is made of resin (silicone rubber in this embodiment).
The first optical film F1 and the second optical film F2 enter between the first roller R9a and the second roller R9b, whereby the first optical film F1 and the second optical film F2 are bonded together to produce a laminate F3 of the first optical film F1 and the second optical film F2. The laminate F3 is transported by the transport roller R12 and taken up by a take-up roller (not shown).
　表面保護フィルム貼合工程ＳＴ５では、図１２（ａ）に示す第１例の場合、積層体Ｆ３のＴＤ方向のカール値が所定の範囲内となるように、第１光学フィルムＦ１の貼合ローラＲ９への進入角度αが調整される。進入角度αの意味は、図３（ｂ）を参照して説明したものと同様である。具体的には、第１搬送ローラＲ１０の貼合ローラＲ９に対する位置を上下方向に調整することで、進入角度αが調整される。図１２（ａ）に実線で示す最上部の位置に第１搬送ローラＲ１０が位置するときに、進入角度αは最も小さい０°となり、一点鎖線で示す最下部の位置に第１搬送ローラＲ１０が位置するときに、進入角度αは最も大きな値となる。
　また、図１２（ｂ）に示す第２例の場合、積層体Ｆ３のＴＤ方向のカール値が所定の範囲内となるように、第２光学フィルムＦ２の貼合ローラＲ９への進入角度βが調整される。進入角度βの意味は、図３（ｂ）を参照して説明したものと同様である。具体的には、第２搬送ローラＲ１１の貼合ローラＲ９に対する位置を上下方向に調整することで、進入角度βが調整される。図１２（ｂ）に実線で示す最下部の位置に第２搬送ローラＲ１１が位置するときに、進入角度βは最も小さい０°となり、一点鎖線で示す最上部の位置に第２搬送ローラＲ１１が位置するときに、進入角度βは最も大きな値となる。 In the surface protective film bonding step ST5, in the case of the first example shown in FIG. 12(a), the approach angle α of the first optical film F1 to the lamination roller R9 is adjusted so that the curl value in the TD direction of the laminate F3 is within a predetermined range. The meaning of the approach angle α is the same as that described with reference to FIG. 3(b). Specifically, the approach angle α is adjusted by adjusting the position of the first conveying roller R10 relative to the lamination roller R9 in the vertical direction. When the first conveying roller R10 is located at the top position shown by the solid line in FIG. 12(a), the approach angle α is the smallest, 0°, and when the first conveying roller R10 is located at the bottom position shown by the dashed line, the approach angle α is the largest.
In the case of the second example shown in FIG. 12(b), the approach angle β of the second optical film F2 to the lamination roller R9 is adjusted so that the curl value in the TD direction of the laminate F3 falls within a predetermined range. The meaning of the approach angle β is the same as that described with reference to FIG. 3(b). Specifically, the approach angle β is adjusted by adjusting the position of the second conveying roller R11 relative to the lamination roller R9 in the vertical direction. When the second conveying roller R11 is located at the bottommost position shown by the solid line in FIG. 12(b), the approach angle β is the smallest, 0°, and when the second conveying roller R11 is located at the topmost position shown by the dashed line, the approach angle β is the largest.
　図１３は、表面保護フィルム貼合工程ＳＴ５で製造された積層体Ｆ３（光学積層体１００）のＴＤ方向のカール値を測定した結果の一例を示す図である。図１３において、符号αで示すデータは、図１２（ａ）に示す第１例で得られたＴＤ方向のカール値であり、符号βで示すデータは、図１２（ｂ）に示す第２例で得られたＴＤ方向のカール値である。具体的には、図１３は、図９に示す例と同様の構成を有する第２中間体Ｍ２に、総厚み４８μｍの表面保護フィルム５（基材：厚み３８μｍのポリエチレンテレフタレート、粘着剤層：厚み１０μｍのアクリル系粘着剤）を貼り付けた積層体Ｆ３（光学積層体）のＴＤ方向のカール値を測定した結果である。なお、図１３の符号αで示すデータは、第２光学フィルムＦ２の貼合ローラＲ９への進入角度β＝３０°のときに得られたものである。また、図１３の符号βで示すデータは、第１光学フィルムＦ１の貼合ローラＲ９への進入角度α＝３０°のときに得られたものである。
　図１３に示すように、第１例については、図５等に示す結果と同様に、第１フィルムＦ１の貼合ローラＲ９への進入角度αに応じて、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値は変化している。同様に、第２例については、第２フィルムＦ２の貼合ローラＲ９への進入角度βに応じて、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値は変化している。
　したがって、第１例の場合は、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が所定の範囲内となるように、第１ローラＲ９ａに接触する第１光学フィルムＦ１の貼合ローラＲ９への進入角度αを調整すれば、貼り合わせ後の積層体Ｆ３、すなわち、最終的に製造される光学積層体１００のＴＤ方向のカール値を所定の範囲内に制御でき、光学積層体１００のＴＤ方向のカール値を使用上問題とならない程度に抑制可能である。また、第２例の場合は、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が所定の範囲内となるように、第２ローラＲ９ｂに接触する第２光学フィルムＦ２の貼合ローラＲ９への進入角度βを調整すれば、貼り合わせ後の積層体Ｆ３、すなわち、最終的に製造される光学積層体１００のＴＤ方向のカール値を所定の範囲内に制御でき、光学積層体１００のＴＤ方向のカール値を使用上問題とならない程度に抑制可能である。
　具体的には、第１例の場合は、図１３に示すようなデータを予め採取しておき、このデータに基づき、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が所定の範囲内となるように、第１ローラＲ９ａに接触する第１光学フィルムＦ１の貼合ローラＲ９への進入角度αを調整すれば、調整後には、貼り合わせ後の積層体Ｆ３、すなわち、最終的に製造される光学積層体１００のＴＤ方向のカール値を所定の範囲内に制御可能である。また、第２例の場合は、図１３に示すようなデータを予め採取しておき、このデータに基づき、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が所定の範囲内となるように、第２ローラＲ９ｂに接触する第２光学フィルムＦ２の貼合ローラＲ９への進入角度βを調整すれば、調整後には、貼り合わせ後の積層体Ｆ３、すなわち、最終的に製造される光学積層体１００のＴＤ方向のカール値を所定の範囲内に制御可能である。 FIG. 13 is a diagram showing an example of the result of measuring the curl value in the TD direction of the laminate F3 (optical laminate 100) manufactured in the surface protective film bonding process ST5. In FIG. 13, the data indicated by the symbol α is the curl value in the TD direction obtained in the first example shown in FIG. 12(a), and the data indicated by the symbol β is the curl value in the TD direction obtained in the second example shown in FIG. 12(b). Specifically, FIG. 13 shows the result of measuring the curl value in the TD direction of the laminate F3 (optical laminate) in which a surface protective film 5 (substrate: polyethylene terephthalate having a thickness of 38 μm, adhesive layer: acrylic adhesive having a thickness of 10 μm) having a total thickness of 48 μm is attached to the second intermediate M2 having the same configuration as the example shown in FIG. 9. The data indicated by the symbol α in FIG. 13 was obtained when the approach angle β of the second optical film F2 to the bonding roller R9 is 30°. Moreover, the data indicated by the symbol β in FIG. 13 was obtained when the approach angle α of the first optical film F1 to the laminating roller R9 was 30°.
13, in the first example, the curl value in the TD direction of the laminate F3 after lamination changes depending on the approach angle α of the first film F1 to the lamination roller R9, similarly to the results shown in Fig. 5 etc. Similarly, in the second example, the curl value in the TD direction of the laminate F3 after lamination changes depending on the approach angle β of the second film F2 to the lamination roller R9.
Therefore, in the case of the first example, if the approach angle α of the first optical film F1 contacting the first roller R9a to the lamination roller R9 is adjusted so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, the TD curl value of the laminate F3 after lamination, i.e., the optical laminate 100 finally manufactured, can be controlled within a predetermined range, and the TD curl value of the optical laminate 100 can be suppressed to a level that does not cause problems in use. In addition, in the case of the second example, if the approach angle β of the second optical film F2 contacting the second roller R9b to the lamination roller R9 is adjusted so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, the TD curl value of the laminate F3 after lamination, i.e., the optical laminate 100 finally manufactured, can be controlled within a predetermined range, and the TD curl value of the optical laminate 100 can be suppressed to a level that does not cause problems in use.
Specifically, in the case of the first example, data as shown in Fig. 13 is collected in advance, and based on this data, the approach angle α of the first optical film F1 in contact with the first roller R9a to the lamination roller R9 is adjusted so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, and after the adjustment, the TD curl value of the laminate F3 after lamination, i.e., the optical laminate 100 finally manufactured, can be controlled within a predetermined range. In the case of the second example, data as shown in Fig. 13 is collected in advance, and based on this data, the approach angle β of the second optical film F2 in contact with the second roller R9b to the lamination roller R9 is adjusted so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, and after the adjustment, the TD curl value of the laminate F3 after lamination, i.e., the optical laminate 100 finally manufactured, can be controlled within a predetermined range.
　図１４は、表面保護フィルム貼合工程ＳＴ５を実行する装置の他の概略構成例及び参考例に係る装置の概略構成を模式的に示す側面図（各フィルムの搬送方向（ＭＤ方向）に直交する水平方向（ＴＤ方向）から見た図）である。図１４（ａ）は第３例を、図１４（ｂ）は参考例を示す。図１４に示す矢符は、各フィルムの搬送方向を意味する。
　図１４（ａ）に示す第３例は、第２ローラＲ９ｂが、その表面が金属（本実施形態では、鉄）から形成された金属ローラである点を除いて、図１２（ａ）に示す第１例と同様の構成を有する。
　図１４（ｂ）に示す参考例は、第２ローラＲ９ｂが、その表面が金属（本実施形態では、鉄）から形成された金属ローラである点を除いて、図１２（ｂ）に示す第２例と同様の構成を有する。 FIG. 14 is a side view (as viewed from a horizontal direction (TD direction) perpendicular to the conveying direction (MD direction) of each film) showing another schematic configuration example of an apparatus that performs the surface protective film bonding process ST5 and a schematic configuration of an apparatus according to a reference example. FIG. 14(a) shows a third example, and FIG. 14(b) shows a reference example. The arrows shown in FIG. 14 indicate the conveying direction of each film.
The third example shown in FIG. 14(a) has a configuration similar to that of the first example shown in FIG. 12(a), except that the second roller R9b is a metal roller whose surface is made of metal (iron in this embodiment).
The reference example shown in FIG. 14(b) has a configuration similar to that of the second example shown in FIG. 12(b), except that the second roller R9b is a metal roller whose surface is made of metal (iron in this embodiment).
　図１５は、表面保護フィルム貼合工程ＳＴ５で製造された積層体Ｆ３（光学積層体１００）のＴＤ方向のカール値を測定した結果の一例を示す図である。図１５において、符号αで示すデータは、図１４（ａ）に示す第３例で得られたＴＤ方向のカール値であり、符号βで示すデータは、図１４（ｂ）に示す参考例で得られたＴＤ方向のカール値である。なお、図１５の符号αで示すデータは、第２光学フィルムＦ２の貼合ローラＲ９への進入角度β＝３０°のときに得られたものである。また、図１５の符号βで示すデータは、第１光学フィルムＦ１の貼合ローラＲ９への進入角度α＝３０°のときに得られたものである。
　図１５に示すように、第３例については、図５等に示す結果と同様に、第１フィルムＦ１の貼合ローラＲ９への進入角度αに応じて、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値は変化している。これに対して、参考例については、第２フィルムＦ２の貼合ローラＲ９への進入角度βに応じて、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値は略一定である。
　したがって、第３例の場合は、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が所定の範囲内となるように、第１ローラＲ９ａに接触する第１光学フィルムＦ１の貼合ローラＲ９への進入角度αを調整すれば、貼り合わせ後の積層体Ｆ３、すなわち、最終的に製造される光学積層体１００のＴＤ方向のカール値を所定の範囲内に制御でき、光学積層体１００のＴＤ方向のカール値を使用上問題とならない程度に抑制可能である。具体的には、図１５に示すようなデータを予め採取しておき、このデータに基づき、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が所定の範囲内となるように、第１ローラＲ９ａに接触する第１光学フィルムＦ１の貼合ローラＲ９への進入角度αを調整すれば、調整後には、貼り合わせ後の積層体Ｆ３、すなわち、最終的に製造される光学積層体１００のＴＤ方向のカール値を所定の範囲内に制御可能である。
　これに対して、参考例の場合は、第２ローラＲ９ｂに接触する第２光学フィルムＦ２の貼合ローラＲ９への進入角度βを調整しても、貼り合わせ後の積層体Ｆ３のＴＤ方向のカール値が略一定であるため、貼り合わせ後の積層体Ｆ３、すなわち、最終的に製造される光学積層体１００のＴＤ方向のカール値を所定の範囲内に制御できず、光学積層体１００のＴＤ方向のカール値を使用上問題とならない程度に抑制できないおそれがある。 15 is a diagram showing an example of the results of measuring the curl value in the TD direction of the laminate F3 (optical laminate 100) manufactured in the surface protective film bonding step ST5. In FIG. 15, the data indicated by the symbol α is the curl value in the TD direction obtained in the third example shown in FIG. 14(a), and the data indicated by the symbol β is the curl value in the TD direction obtained in the reference example shown in FIG. 14(b). The data indicated by the symbol α in FIG. 15 was obtained when the approach angle β of the second optical film F2 to the bonding roller R9 was 30°. The data indicated by the symbol β in FIG. 15 was obtained when the approach angle α of the first optical film F1 to the bonding roller R9 was 30°.
15, in the third example, the curl value in the TD direction of the laminate F3 after lamination changes depending on the approach angle α of the first film F1 to the lamination roller R9, similar to the results shown in Fig. 5 etc. In contrast, in the reference example, the curl value in the TD direction of the laminate F3 after lamination is approximately constant depending on the approach angle β of the second film F2 to the lamination roller R9.
Therefore, in the case of the third example, if the approach angle α of the first optical film F1 contacting the first roller R9a to the lamination roller R9 is adjusted so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, the TD curl value of the laminate F3 after lamination, i.e., the optical laminate 100 finally manufactured, can be controlled within a predetermined range, and the TD curl value of the optical laminate 100 can be suppressed to a level that does not cause problems in use. Specifically, data such as that shown in FIG. 15 is collected in advance, and based on this data, if the approach angle α of the first optical film F1 contacting the first roller R9a to the lamination roller R9 is adjusted so that the TD curl value of the laminate F3 after lamination falls within a predetermined range, after the adjustment, the TD curl value of the laminate F3 after lamination, i.e., the optical laminate 100 finally manufactured, can be controlled within a predetermined range.
In contrast, in the reference example, even if the approach angle β of the second optical film F2, which contacts the second roller R9b, to the lamination roller R9 is adjusted, the TD curl value of the laminate F3 after lamination is approximately constant, so the TD curl value of the laminate F3 after lamination, i.e., the optical laminate 100 that is finally manufactured, cannot be controlled within a specified range, and there is a risk that the TD curl value of the optical laminate 100 cannot be suppressed to a level that does not cause problems in use.
　以上に説明した本実施形態に係る製造方法によれば、従来用いられている光学積層体１００の構成要素の材質を特に変えることなく、カールを効果的に抑制可能である。
　なお、本実施形態では、はく離ライナー貼合工程ＳＴ３、検査工程ＳＴ４及び表面保護フィルム貼合工程ＳＴ５の３つの工程において、本発明を適用する、すなわち、貼合ローラを構成する樹脂ローラに接触する光学フィルムの貼合ローラへの進入角度を調整する場合を例に挙げて説明したが、本発明はこれに限るものではない。各工程ＳＴ３～ＳＴ５のうち、何れか１つ又は２つの工程のみに適用してもよいし、フィルムを貼り合わせる他の工程に適用することも可能である。 According to the manufacturing method according to the present embodiment described above, curling can be effectively suppressed without particularly changing the materials of the components of the optical laminate 100 that have been conventionally used.
In this embodiment, the present invention is applied to three steps, namely, the release liner laminating step ST3, the inspection step ST4, and the surface protective film laminating step ST5, that is, the case where the approach angle of the optical film contacting the resin roller constituting the laminating roller to the laminating roller is adjusted has been described as an example, but the present invention is not limited thereto. The present invention may be applied to only one or two of the steps ST3 to ST5, or may be applied to other steps in which films are laminated.
　また、本実施形態では、偏光板１０が偏光フィルム１と位相差フィルム２との積層体である態様を例に挙げて説明したが、本発明はこれに限定されるものではない。偏光板１０が偏光フィルム１と位相差フィルム２と更に他の構成要素との積層体である態様や、位相差フィルム２が存在せずに偏光板１０が偏光フィルム１と他の構成要素との積層体である態様や、偏光板１０に偏光フィルム１のみが存在する態様などを採用することも可能である。 In addition, in this embodiment, the polarizing plate 10 is a laminate of the polarizing film 1 and the retardation film 2, but the present invention is not limited to this. It is also possible to adopt an embodiment in which the polarizing plate 10 is a laminate of the polarizing film 1, the retardation film 2, and other components, an embodiment in which the retardation film 2 is not present and the polarizing plate 10 is a laminate of the polarizing film 1 and other components, or an embodiment in which only the polarizing film 1 is present in the polarizing plate 10.
　１・・・偏光フィルム
　３・・・粘着剤層
　４・・・はく離ライナー
　５・・・表面保護フィルム
　１０・・・偏光板
　１００・・・光学積層体
　Ｆ１・・・第１光学フィルム
　Ｆ２・・・第２光学フィルム
　Ｍ１・・・第１中間体
　Ｍ２・・・第２中間体
　Ｒ１、Ｒ５、Ｒ９・・・貼合ローラ
　Ｒ１ａ、Ｒ５ａ、Ｒ９ａ・・・第１ローラ
　Ｒ１ｂ、Ｒ５ｂ、Ｒ９ｂ・・・第２ローラ
　Ｒ２、Ｒ６、Ｒ１０・・・第１搬送ローラ
　Ｒ３、Ｒ７、Ｒ１１・・・第２搬送ローラ
　α、β・・・進入角 REFERENCE SIGNS LIST 1: Polarizing film 3: Pressure-sensitive adhesive layer 4: Release liner 5: Surface protective film 10: Polarizing plate 100: Optical laminate F1: First optical film F2: Second optical film M1: First intermediate M2: Second intermediate R1, R5, R9: Lamination rollers R1a, R5a, R9a: First roller R1b, R5b, R9b: Second roller R2, R6, R10: First conveyor roller R3, R7, R11: Second conveyor roller α, β: Approach angle

Claims (7)

  1. 　長手方向に搬送される偏光板を含む長尺帯状の第１光学フィルムと、長手方向に搬送される長尺帯状の第２光学フィルムとを、粘着剤層を介して、貼合ローラによって貼り合わせる工程を有する光学積層体の製造方法であって、
    　前記貼合ローラは、前記第１光学フィルムに接触する第１ローラと、前記第１ローラに対向して配置され、前記第２光学フィルムに接触する第２ローラと、から構成され、前記第１光学フィルム及び前記第２光学フィルムが前記第１ローラと前記第２ローラとの間に進入することで、前記第１光学フィルムと前記第２光学フィルムとが貼り合わせられ、
    　前記第１ローラ及び前記第２ローラのうち、少なくとも何れか一方のローラの表面は樹脂から形成されており、
    　前記第１ローラの表面が樹脂から形成されている場合に、前記第１光学フィルムと前記第２光学フィルムとの積層体の長手方向に直交する方向のカール値が所定の範囲内となるように、前記第１光学フィルムの前記貼合ローラへの進入角度を調整するか、又は、前記第２ローラの表面が樹脂から形成されている場合に、前記第１光学フィルムと前記第２光学フィルムとの積層体の長手方向に直交する方向のカール値が所定の範囲内となるように、前記第２光学フィルムの前記貼合ローラへの進入角度を調整する、
    光学積層体の製造方法。     A method for producing an optical laminate, comprising a step of bonding a long strip-shaped first optical film including a polarizing plate transported in a longitudinal direction and a long strip-shaped second optical film transported in the longitudinal direction, via a pressure-sensitive adhesive layer, by a lamination roller,
    the lamination roller is composed of a first roller that contacts the first optical film and a second roller that is disposed opposite to the first roller and that contacts the second optical film, the first optical film and the second optical film are laminated together by the first roller and the second roller entering between the first roller and the second roller,
    a surface of at least one of the first roller and the second roller is made of resin,
    When the surface of the first roller is made of resin, an angle of entry of the first optical film into the lamination roller is adjusted so that a curl value in a direction perpendicular to the longitudinal direction of the laminate of the first optical film and the second optical film falls within a predetermined range; or, when the surface of the second roller is made of resin, an angle of entry of the second optical film into the lamination roller is adjusted so that a curl value in a direction perpendicular to the longitudinal direction of the laminate of the first optical film and the second optical film falls within a predetermined range.
    A method for producing an optical laminate.
  2. 　前記第１ローラの表面が樹脂から形成されている、
    請求項１に記載の光学積層体の製造方法。     the surface of the first roller is formed from a resin;
    A method for producing the optical laminate according to claim 1 .
  3. 　前記第１ローラの表面が樹脂から形成されている場合に、前記貼合ローラの入側に前記第１光学フィルムに接触する第１搬送ローラを配置し、前記第１搬送ローラの前記貼合ローラに対する位置を調整することで、前記第１光学フィルムの前記貼合ローラへの進入角度を調整するか、又は、前記第２ローラの表面が樹脂から形成されている場合に、前記貼合ローラの入側に前記第２光学フィルムに接触する第２搬送ローラを配置し、前記第２搬送ローラの前記貼合ローラに対する位置を調整することで、前記第２光学フィルムの前記貼合ローラへの進入角度を調整する、
    請求項１又は２に記載の光学積層体の製造方法。     When the surface of the first roller is made of resin, a first transport roller that comes into contact with the first optical film is disposed on the entry side of the lamination roller, and the position of the first transport roller with respect to the lamination roller is adjusted to adjust the angle of entry of the first optical film into the lamination roller; or, when the surface of the second roller is made of resin, a second transport roller that comes into contact with the second optical film is disposed on the entry side of the lamination roller, and the position of the second transport roller with respect to the lamination roller is adjusted to adjust the angle of entry of the second optical film into the lamination roller.
    A method for producing the optical laminate according to claim 1 or 2.
  4. 　前記第２光学フィルムがはく離ライナーであり、
    　前記第２ローラの表面が金属から形成されている、
    請求項１又は２に記載の光学積層体の製造方法。     the second optical film is a release liner;
    the surface of the second roller is made of metal;
    A method for producing the optical laminate according to claim 1 or 2.
  5. 　前記第２光学フィルムが表面保護フィルムである、
    請求項１又は２に記載の光学積層体の製造方法。     The second optical film is a surface protection film.
    A method for producing the optical laminate according to claim 1 or 2.
  6. 　前記第１ローラの表面が樹脂から形成されている場合に、前記第１光学フィルムの前記貼合ローラへの進入角度を７５°以下に調整するか、又は、前記第２ローラの表面が樹脂から形成されている場合に、前記第２光学フィルムの前記貼合ローラへの進入角度を７５°以下に調整する、
    請求項１又は２に記載の光学積層体の製造方法。     When the surface of the first roller is made of resin, an approach angle of the first optical film to the lamination roller is adjusted to 75° or less, or when the surface of the second roller is made of resin, an approach angle of the second optical film to the lamination roller is adjusted to 75° or less.
    A method for producing the optical laminate according to claim 1 or 2.
  7. 　前記第１ローラの表面が樹脂から形成されている場合には、前記第１ローラの表面がゴムから形成され、
    　前記第２ローラの表面が樹脂から形成されている場合には、前記第２ローラの表面がゴムから形成されている、
    請求項１又は２に記載の光学積層体の製造方法。     When the surface of the first roller is made of resin, the surface of the first roller is made of rubber,
    When the surface of the second roller is made of resin, the surface of the second roller is made of rubber.
    A method for producing the optical laminate according to claim 1 or 2.
PCT/JP2023/030511 2022-10-18 2023-08-24 Method for producing optical laminate WO2024084805A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005007748A (en) * 2003-06-19 2005-01-13 Yodogawa Hu-Tech Kk Film sticking device
JP2011158908A (en) * 2011-03-01 2011-08-18 Nitto Denko Corp Method for producing liquid crystal display element
JP2013080219A (en) * 2011-09-21 2013-05-02 Sumitomo Chemical Co Ltd Method of manufacturing polarizer
JP2015090388A (en) * 2013-11-05 2015-05-11 住友化学株式会社 Method for manufacturing laminated optical film

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005007748A (en) * 2003-06-19 2005-01-13 Yodogawa Hu-Tech Kk Film sticking device
JP2011158908A (en) * 2011-03-01 2011-08-18 Nitto Denko Corp Method for producing liquid crystal display element
JP2013080219A (en) * 2011-09-21 2013-05-02 Sumitomo Chemical Co Ltd Method of manufacturing polarizer
JP2015090388A (en) * 2013-11-05 2015-05-11 住友化学株式会社 Method for manufacturing laminated optical film

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