WO2013146163A1 - Polarizing plate fabrication method and fabrication apparatus - Google Patents

Polarizing plate fabrication method and fabrication apparatus Download PDF

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Publication number
WO2013146163A1
WO2013146163A1 PCT/JP2013/056269 JP2013056269W WO2013146163A1 WO 2013146163 A1 WO2013146163 A1 WO 2013146163A1 JP 2013056269 W JP2013056269 W JP 2013056269W WO 2013146163 A1 WO2013146163 A1 WO 2013146163A1
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WO
WIPO (PCT)
Prior art keywords
ultraviolet
optical film
film
polarizing plate
bonding
Prior art date
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PCT/JP2013/056269
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French (fr)
Japanese (ja)
Inventor
弘明 高畑
清水　英満
公彦 矢可部
Original Assignee
住友化学株式会社
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Application filed by 住友化学株式会社 filed Critical 住友化学株式会社
Priority to KR20147024335A priority Critical patent/KR20150002598A/en
Publication of WO2013146163A1 publication Critical patent/WO2013146163A1/en

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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J5/00—Adhesive processes in general; Adhesive processes not provided for elsewhere, e.g. relating to primers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/306—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl acetate or vinyl alcohol (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/10—Coating on the layer surface on synthetic resin layer or on natural or synthetic rubber layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2255/00—Coating on the layer surface
    • B32B2255/26—Polymeric coating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B32B2457/20—Displays, e.g. liquid crystal displays, plasma displays
    • B32B2457/202—LCD, i.e. liquid crystal displays
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2203/00—Applications of adhesives in processes or use of adhesives in the form of films or foils
    • C09J2203/318—Applications of adhesives in processes or use of adhesives in the form of films or foils for the production of liquid crystal displays
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J2301/00—Additional features of adhesives in the form of films or foils
    • C09J2301/40—Additional features of adhesives in the form of films or foils characterized by the presence of essential components
    • C09J2301/416—Additional features of adhesives in the form of films or foils characterized by the presence of essential components use of irradiation
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid

Definitions

  • the present invention relates to a manufacturing method and a manufacturing apparatus of a polarizing plate used as a liquid crystal display member.
  • the liquid crystal panel that forms the core of a liquid crystal display device is usually configured by disposing polarizing plates on both sides of a liquid crystal cell.
  • a polarizing plate has a structure in which a protective film made of a transparent resin is bonded to one surface of a polarizing film made of a polyvinyl alcohol resin through an adhesive.
  • a transparent resin film is often bonded to the other surface of the polarizing film via an adhesive, and the transparent resin film on this side has only a protective function for the polarizing film, similar to the protective film on the opposite side.
  • the protective function it may be a so-called retardation film provided with an in-plane and / or thickness direction retardation for the purpose of optical compensation and viewing angle compensation of the liquid crystal cell.
  • optical film such a protective film or retardation film bonded to a polarizing film via an adhesive
  • the adhesive used for bonding the optical film to the polarizing film is generally a liquid, and exhibits an adhesive force between the polarizing film and the optical film by the curing reaction of the liquid adhesive.
  • the active energy ray curable adhesive is prepared in liquid form, and the die coater that directly applies the liquid adhesive to the object to be coated, or the liquid adhesive that is supported on the groove formed on the surface, is applied to the surface of the object to be coated.
  • the die coater that directly applies the liquid adhesive to the object to be coated, or the liquid adhesive that is supported on the groove formed on the surface, is applied to the surface of the object to be coated.
  • the optical film is preliminarily applied to the bonding surface to the polarizing film.
  • the polarizing film is piled up on the adhesive coating surface, active energy rays, such as an ultraviolet-ray and an electron beam, are irradiated, an adhesive agent is hardened, and adhesive force is expressed.
  • the method using such an active energy ray-curable adhesive is a very effective method because there are many applicable optical films.
  • a protective film is laminated on both surfaces of a polarizing film via an adhesive.
  • a method is disclosed in which a laminate is obtained, and active energy rays are irradiated while the laminate is brought into close contact with the outer surface of a convex curved surface formed in an arc shape along the conveying direction of the laminate. According to this method, the reverse curl and wave curl that are likely to occur in the obtained polarizing plate can be suppressed, and a polarizing plate having good performance can be produced.
  • ultraviolet rays When ultraviolet rays are used as active energy rays, it is common to use ultraviolet rays having a high energy and a short wavelength region of 400 nm or less.
  • the adhesive to be used an adhesive that reacts in this wavelength region and causes a curing reaction is generally used.
  • this ultraviolet curable adhesive it is possible to produce a polarizing plate with good adhesion between the polarizing film and the optical film, but in order to cure with ultraviolet rays in the above wavelength range, It can be considered that the film is cured by illumination such as a mercury lamp or a fluorescent lamp included in the polarizing plate manufacturing apparatus installed in the factory or in the facility.
  • the UV curable adhesive before use (coating) is prepared for the adhesive coating means of the polarizing plate manufacturing apparatus.
  • an ultraviolet curable adhesive before use if an unintended curing reaction is caused by the ultraviolet irradiation from the illumination, the adhesive performance may be deteriorated.
  • the polarizing film and the optical film are overlapped with the end face of the polarizing film or optical film coated with the ultraviolet curable adhesive or the coated ultraviolet curable adhesive.
  • An uncured ultraviolet curable adhesive may protrude from the end face of the laminate to be adhered to a guide roll or the like that transports the film.
  • the UV curable adhesive attached to the guide roll, etc. when an unintended curing reaction occurs due to the UV irradiation from the illumination, the UV curable adhesive attached to the guide roll etc. is removed and manufactured. It takes a lot of time to restore the process, and the operating rate of the manufacturing process is significantly reduced.
  • An object of the present invention is to prevent unintentional curing of an ultraviolet curable adhesive in the production of a polarizing plate in which an optical film is bonded to a polarizing film via an ultraviolet curable adhesive.
  • An object of the present invention is to provide a method for efficiently producing a polarizing plate having good adhesiveness without significantly reducing the operating rate of the production process.
  • the other object of this invention is to provide the polarizing plate manufacturing apparatus which can implement suitably the manufacturing method of the above polarizing plates.
  • the present inventors have a specific emission wavelength as illumination of a polarizing plate manufacturing facility (factory) or a polarizing plate manufacturing apparatus installed in the facility.
  • LED illumination By using LED illumination, the curing reaction of the ultraviolet curable adhesive used when laminating the polarizing film and the optical film is performed only in the ultraviolet irradiation process using the ultraviolet irradiation means, and other than this process.
  • the present inventors have found that an unintended curing reaction can be suppressed and have completed the present invention.
  • the present invention includes the following.
  • a method of manufacturing a polarizing plate by laminating an optical film made of a thermoplastic resin to a polarizing film made of a polyvinyl alcohol resin through an ultraviolet curable adhesive (A) a coating step of applying the ultraviolet curable adhesive to at least one bonding surface of the polarizing film and the optical film; (B) A laminating step of obtaining a laminate by superimposing the polarizing film and the optical film through the coated ultraviolet curable adhesive, and (C) irradiating the laminate with ultraviolet rays, Including an ultraviolet irradiation step of curing the ultraviolet curable adhesive; LED in which the coating step (A), the bonding step (B), and the ultraviolet irradiation step (C) have a light emission wavelength in a wavelength region exceeding 400 nm and no light emission wavelength in a wavelength region of 250 to 400 nm A method for producing a polarizing plate carried out under illumination.
  • the coating step is performed.
  • An apparatus for producing a polarizing plate by laminating an optical film made of a thermoplastic resin to a polarizing film made of a polyvinyl alcohol resin through an ultraviolet curable adhesive (A1) Coating means for applying the ultraviolet curable adhesive to at least one bonding surface of the polarizing film and the optical film, (B1) A bonding means for obtaining a laminate by superimposing the polarizing film and the optical film via the coated ultraviolet curable adhesive, (C1) Ultraviolet irradiation means for irradiating the laminate with ultraviolet rays to cure the ultraviolet curable adhesive, and (D1) The coating means (A1), the bonding means (B1), and the ultraviolet irradiation.
  • An apparatus for producing a polarizing plate comprising: LED illumination for illuminating the means (C1), having an emission wavelength in a wavelength range exceeding 400 nm and no emission wavelength in a wavelength range of 250 to 400 nm.
  • the curing reaction of the ultraviolet curable adhesive used when laminating the polarizing film and the optical film can be performed only in the ultraviolet irradiation process using the ultraviolet irradiation means,
  • the unintended curing reaction of the previous ultraviolet curable adhesive and the unintended curing reaction of the uncured ultraviolet curable adhesive attached to the guide roll or the like can be effectively suppressed. Therefore, a polarizing plate having good adhesion between the polarizing film and the optical film can be efficiently produced without significantly reducing the operating rate of the production process.
  • the coating state of the adhesive on the film during the polarizing plate manufacturing process can be clearly confirmed visually, which is advantageous for visually detecting defects in the coating state of the adhesive. is there.
  • FIG. 1 It is a schematic side view which shows an example of the polarizing plate manufacturing apparatus of this invention. It is an illumination intensity spectrum of LED illumination used in Example 1.
  • FIG. It is an illuminance spectrum of the ultraviolet cut fluorescent lamp used in Comparative Example 1. It is an illumination intensity spectrum of the fluorescent lamp used in Comparative Example 2.
  • an optical film made of a thermoplastic resin is bonded to a polarizing film made of a polyvinyl alcohol resin through an ultraviolet curable adhesive to produce a polarizing plate.
  • the optical film may be bonded only to one side of the polarizing film, or may be bonded to both sides of the polarizing film.
  • the polarizing film is made of polyvinyl alcohol-based resin, and is a film having a property of transmitting light having a vibration surface in a certain direction among light incident on the film and absorbing light having a vibration surface perpendicular thereto. Typically, it is a film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin.
  • the polyvinyl alcohol resin constituting the polarizing film can be obtained by saponifying a polyvinyl acetate resin.
  • the polyvinyl acetate resin used as a raw material for the polyvinyl alcohol resin is not only polyvinyl acetate, which is a homopolymer of vinyl acetate, but also a copolymer of vinyl acetate and other monomers copolymerizable therewith. May be.
  • a polarizing film is obtained by subjecting a film made of polyvinyl alcohol resin to uniaxial stretching treatment, dyeing treatment with a dichroic dye, and boric acid crosslinking treatment after dyeing.
  • a dichroic dye iodine or a dichroic organic dye is used.
  • Uniaxial stretching may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing with a dichroic dye, or after dyeing with a dichroic dye, for example, during a boric acid crosslinking treatment. May be.
  • a polarizing film made of a polyvinyl alcohol-based resin thus manufactured and having a dichroic dye adsorbed and oriented is one of the raw materials for the polarizing plate.
  • optical film An optical film made of a thermoplastic resin is bonded to the polarizing film to produce a polarizing plate.
  • the optical film preferably has a refractive index measured by D-ray at a temperature of 20 ° C. in the range of 1.4 to 1.7.
  • the refractive index of the optical film is measured according to JIS K 0062: 1992 “Method for measuring refractive index of chemical product”. If the optical film has a refractive index in this range, it will have excellent display characteristics when the produced polarizing plate is incorporated in a liquid crystal panel. For the same reason, the preferred refractive index of the optical film is in the range of 1.45 to 1.67.
  • the optical film has a haze value in the range of about 0.001 to 10%, which improves the contrast of the obtained polarizing plate, particularly when it is incorporated into a liquid crystal panel to display black and has a problem such as a decrease in luminance. This is preferable because the possibility of occurrence of is reduced.
  • the haze value is a value defined by (diffuse transmittance / total light transmittance) ⁇ 100 (%), and is measured in accordance with JIS K 7136: 2000 “How to determine haze of plastic and transparent material”.
  • thermoplastic resin constituting the optical film examples include the following, and here, the refractive index measured by the D line at a temperature of 20 ° C. is also displayed as n D (20 ° C.).
  • the cycloolefin resin is a polymer having a cycloolefin monomer such as norbornene as a main structural unit, a resin obtained by hydrogenating a ring-opening polymer of a cycloolefin monomer, a cycloolefin monomer, Examples include addition polymers with chain olefin monomers having 2 to 10 carbon atoms such as ethylene and propylene and / or aromatic vinyl monomers such as styrene.
  • the crystalline polyolefin resin is a polymer mainly composed of a chain olefin monomer having 2 to 10 carbon atoms, which is a homopolymer of a chain olefin monomer and two or more types of chain olefin monomers. Binary or ternary or higher copolymers using are included. Specifically, a polyethylene resin, a polypropylene resin, an ethylene-propylene copolymer, a homopolymer of 4-methyl-1-pentene, a copolymer of 4-methyl-1-pentene and ethylene or propylene, etc. Is included.
  • Polyester resin includes aliphatic polyester as well as aromatic polyester such as polyethylene terephthalate resin and polyethylene naphthalate resin.
  • the polycarbonate resin is typically a polymer obtained by a reaction of bisphenol A and phosgene, and having a carbonate bond —O—CO—O— in the main chain.
  • the acrylic resin is typically a polymer mainly composed of methyl methacrylate. In addition to a methyl methacrylate homopolymer, methyl methacrylate and other methacrylate esters and / or acrylic esters. And copolymers thereof are also included.
  • Triacetyl cellulose resin is an acetate of cellulose. From these thermoplastic resins, a film can be formed into a film by a solvent casting method, a melt extrusion method, or the like to obtain an optical film used in the present invention. Moreover, what was extended
  • the optical film preferably has a thickness of usually about 5 to 200 ⁇ m. If the optical film is too thin, the handling property is lacking, and there is a high possibility that the optical film will be broken in the polarizing plate production line or cause wrinkles. On the other hand, if it is too thick, the resulting polarizing plate becomes thick and the weight increases, which may impair the commercial properties. For these reasons, a more preferable thickness of the optical film is 10 to 120 ⁇ m, and a more preferable thickness is 10 to 85 ⁇ m.
  • UV curable adhesive When bonding an optical film to a polarizing film, first, an ultraviolet curable adhesive is applied to at least one bonding surface of the polarizing film and the optical film. Typically, an ultraviolet curable adhesive is applied to the bonding surface of the optical film to the polarizing film.
  • the thickness of the ultraviolet curable adhesive is preferably in the range of 0.5 to 5 ⁇ m. If the thickness is less than 0.5 ⁇ m, uneven adhesion strength may occur. On the other hand, when the thickness exceeds 5 ⁇ m, not only the manufacturing cost increases, but also the hue of the polarizing plate may be affected depending on the kind of the adhesive.
  • the thickness is relatively large within the above range, for example, 3.5 ⁇ m or more, especially 4 ⁇ m or more, even if the thickness slightly varies, defects such as bubbles are less likely to appear. Since increasing the thickness may lead to an increase in cost, it is desirable to reduce the thickness as much as possible. For these reasons, the preferred thickness of the adhesive is in the range of 1 to 4 ⁇ m, more preferably 1.5 to 3.5 ⁇ m.
  • the UV curable adhesive is supplied in a liquid coatable state, it can be any of those conventionally used in the production of polarizing plates, but from the viewpoint of weather resistance, polymerizability, etc.
  • a cationically polymerizable compound such as an epoxy compound, more specifically, an epoxy compound having no aromatic ring in the molecule, as described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-245925).
  • An adhesive contained as one of the ultraviolet curable components is preferred.
  • the epoxy compound is, for example, a hydrogenated epoxy compound obtained by nuclear hydrogenation of an aromatic polyhydroxy compound which is a raw material of an aromatic epoxy compound represented by diglycidyl ether of bisphenol A and glycidyl ether.
  • an alicyclic epoxy compound having at least one epoxy group bonded to the alicyclic ring in the molecule and an aliphatic epoxy compound typified by a glycidyl ether of an aliphatic polyhydroxy compound.
  • UV curable adhesives In addition to cationically polymerizable compounds, typically epoxy compounds, UV curable adhesives usually generate polymerization initiators, especially cationic species or Lewis acids upon irradiation with ultraviolet rays, and polymerize cationically polymerizable compounds.
  • a photocationic polymerization initiator for initiating the reaction is blended.
  • a thermal cationic polymerization initiator that initiates polymerization by heating, and various other additives such as a photosensitizer may be blended.
  • the ultraviolet curable adhesive applied to each optical film may be the same or different, but from the viewpoint of productivity, moderate adhesion It is preferable to use the same UV curable adhesive on both sides on the premise that strength can be obtained.
  • polarizing plate manufacturing method and polarizing plate manufacturing apparatus an optical film is bonded to the polarizing film which consists of a polyvinyl alcohol-type resin demonstrated above through an ultraviolet curable adhesive, and a polarizing plate is manufactured.
  • the manufacturing method of the polarizing plate of this invention contains the following (A), (B) and (C) in this order.
  • A a coating step of applying an ultraviolet curable adhesive to at least one bonding surface of the polarizing film and the optical film;
  • B A laminating step in which a polarizing film and an optical film are superposed through a coated ultraviolet curable adhesive to obtain a laminate, and
  • C an ultraviolet curable adhesive by irradiating the laminate with ultraviolet rays. UV irradiation process to cure.
  • the coating step (A), the bonding step (B), and the ultraviolet irradiation step (C) have an emission wavelength in a wavelength region exceeding 400 nm and do not have an emission wavelength in a wavelength region of 250 to 400 nm. Implemented under LED lighting.
  • the polarizing plate production apparatus of the present invention is an apparatus that can suitably carry out the polarizing plate production method according to the present invention, and includes the following (A1), (B1), (C1), and (D1).
  • FIG. 1 is a side view schematically showing an example of a polarizing plate production apparatus of the present invention.
  • the first optical film 2 is bonded to one surface while the polarizing film 1 is continuously conveyed, and the second optical film 3 is bonded to the other surface.
  • the polarizing plate 4 is manufactured by bonding, and is wound around the winding roll 30.
  • an optical film is bonded to both surfaces of the polarizing film 1, but a mode in which the optical film is bonded only to one surface of the polarizing film 1 is also included in the present invention.
  • the form in that case will be understood by a person skilled in the art to the extent that it can be easily implemented by excluding the description of the other optical film from the following description.
  • the coating step (A) one of the first optical film 2 and the second optical film 3 fed out from the roll bodies 31 and 32.
  • the surface is coated with an ultraviolet curable adhesive from the gravure rolls 11 and 13 of the first coating machine 10 and the second coating machine 12 which are the coating means (A1).
  • a conveying guide roll 24 is appropriately provided on one surface of the polarizing film 1 and the surface of the first optical film 2 and the second optical film 3 opposite to the surface to which the ultraviolet curable adhesive is applied.
  • a conveying guide roll 24 is appropriately provided on one surface of the polarizing film 1 and the surface of the first optical film 2 and the second optical film 3 opposite to the surface to which the ultraviolet curable adhesive is applied.
  • the first optical film 2 and the second optical film 3 to which the ultraviolet curable adhesive has been applied are overlapped on both surfaces of the polarizing film 1, respectively.
  • the laminate is obtained by being pressed between the nip rolls 20 and 21 for bonding, which is a bonding means (B1), in the thickness direction.
  • the laminate is irradiated with ultraviolet rays using the ultraviolet irradiation device 14 which is the ultraviolet irradiation means (C1), and the ultraviolet curable adhesive is cured.
  • the obtained polarizing plate 4 is wound around the winding roll 30 via the nip rolls 22 and 23 before winding.
  • the optical film when the optical film is bonded only to one surface of the polarizing film 1, only one of the first optical film 2 and the second optical film 3 shown in FIG. Only one optical film 2) may be applied.
  • the straight arrows in the figure indicate the film flow direction, and the curved arrows indicate the roll rotation direction.
  • Coating process (A) In the coating step (A), an ultraviolet curable adhesive is applied to the bonding surfaces of the first and second optical films 2 and 3 to the polarizing film 1.
  • the coating machine as the coating means (A1) used here preferably has a means for controlling the coating thickness, and as such a gravure roll 11 described with reference to FIG. , 13 is typical.
  • the gravure rolls 11 and 13 are rolls having concave grooves, and the concave grooves are filled with an ultraviolet curable adhesive in advance, and the first and second optical films 2 and 3 are rotated in this state.
  • the ultraviolet curable adhesive is transferred onto the first and second optical films 2 and 3.
  • Examples of the coating machine using the gravure rolls 11 and 13 include a direct gravure coater, a chamber doctor coater, an offset gravure coater, a kiss coater using a gravure roll, and a reverse roll coater composed of a plurality of rolls.
  • a comma coater that has a cylindrical blade, supplies the coating part with an adhesive, and scrapes it off with the blade, and applies a slot die to directly apply the adhesive.
  • Various coating machines such as a knife coater that creates a reservoir and scrapes off excess liquid with a knife, can be used.
  • direct gravure coater, chamber doctor coater, offset gravure coater, etc. are preferable among coating machines using gravure rolls, considering thin film coating and pass line freedom, etc.
  • a die coater using a slot die is also preferable.
  • a chamber doctor coater is more preferable because it can easily cope with the widening of the polarizing plate and hardly releases the odor of the ultraviolet curable adhesive supplied as a liquid.
  • the chamber doctor coater makes the gravure roll contact the chamber doctor that has absorbed the liquid paint (adhesive), and transfers the paint (adhesive) in the chamber doctor to the concave groove of the gravure roll.
  • a coating machine that transfers the film to the first and second optical films 2 and 3.
  • the compact design is also called a microchamber doctor coater.
  • the thickness of the adhesive layer can be adjusted by the speed ratio of the gravure roll to the line speed.
  • the line speed of the first and second optical films 2 and 3 is set to 10 to 50 m / min, and the gravure roll is rotated in the opposite direction with respect to the conveying direction of the first and second optical films 2 and 3.
  • the thickness of the adhesive layer can be adjusted to 0.5 to 5 ⁇ m, for example. Since the thickness of the adhesive layer is also affected by the porosity of the gravure roll surface, it is preferable to select a gravure roll having a surface porosity suitable for the set thickness in advance.
  • the system which rotates a gravure roll reversely with respect to the conveyance direction of the 1st, 2nd optical films 2 and 3 is also called a reverse gravure.
  • the thickness of the adhesive layer applied to the bonding surface of the first and second optical films 2 and 3 with the polarizing film 1 is measured, and the adhesive layer It is preferable to control the thickness of the film so as to be constant.
  • a measurement method an arbitrary method such as a light interference method, a laser light interference method, an ultrasonic method, a method using radiation such as ⁇ rays or X rays can be adopted.
  • the thickness of the first and second optical films 2 and 3 is measured, the total thickness of the adhesive and the optical film after coating is measured, and the adhesive layer is determined from the absolute value of the difference between these measured values.
  • the method of obtaining the thickness of the film is preferable from the viewpoint of high measurement accuracy and measurement stability.
  • the polarizing film 1 is directly applied to a polyvinyl alcohol resin film in a state of being manufactured through a uniaxial stretching process, a dyeing process with a dichroic dye, and a boric acid crosslinking process after dyeing in a polarizing film manufacturing process (not shown). Often, it is provided to the step (A), but of course, the polarizing film manufactured in the polarizing film manufacturing step may be once wound around a roll and then fed out again by a feeding machine. On the other hand, the first optical film 2 and the second optical film 3 are fed out from the roll bodies 31 and 32 by a feeding machine, respectively.
  • Each film is conveyed so as to have the same flow direction at the same line speed, for example, a line speed of about 10 to 50 m / min.
  • the first optical film 2 and the second optical film 3 are fed out while applying a tension of about 50 to 1000 N / m in the flow direction.
  • Pasting process (B) After passing through the coating step (A), there is a bonding step (B) in which the polarizing film 1 is stacked and pressed on each adhesive coating surface of the first and second optical films 2 and 3 to obtain a laminate. Done.
  • a well-known means can be used for the bonding means (B1) in this process, as shown in FIG. 1, a pair of bonding is possible from a viewpoint that pressurization and bonding are possible while continuously conveying.
  • a method of sandwiching between the nip rolls 20 and 21 is preferable. In this case, it is desirable that the timing of superimposing the first and second optical films 2 and 3 on the polarizing film 1 and the timing of applying pressure by the pair of nip rolls 20 and 21 are the same.
  • the combination of the pair of nip rolls 20 and 21 may be any of metal roll / metal roll, metal roll / rubber roll, rubber roll / rubber roll, and the like.
  • the pressure during pressurization is preferably about 150 to 500 N / cm as the linear pressure when sandwiched between the pair of nip rolls 20 and 21.
  • UV irradiation process As described above, after the first and second optical films 2 and 3 are bonded to the polarizing film 1 to obtain a laminate, an adhesive layer made of an ultraviolet curable adhesive is cured by irradiation with ultraviolet rays.
  • the polarizing plate 4 is manufactured through the ultraviolet irradiation step (C).
  • This ultraviolet irradiation step (C) is performed by irradiating the laminate with ultraviolet rays from the ultraviolet irradiation device 14 as the ultraviolet irradiation means (C1). In this step, ultraviolet light having energy necessary for curing the ultraviolet curable adhesive is irradiated through the first optical film 2 (or the second optical film 3).
  • irradiation of the laminate with ultraviolet rays applied tension to the laminate between the nip rolls 20 and 21 for bonding before and after the ultraviolet irradiation device 14 and the nip rolls 22 and 23 before winding. It is to be performed in the state.
  • the present invention is not limited to this, for example, a convex curved surface formed in an arc shape along the conveying direction as disclosed in the above-mentioned Patent Document 2 (Japanese Patent Laid-Open No. 2009-134190), typically the outer peripheral surface of the roll. It is also preferable to irradiate with ultraviolet rays while being supported by the substrate.
  • the roll supporting the laminated body can be adjusted in temperature in the range of about 10 to 60 ° C.
  • the ultraviolet irradiation device 14 may be provided at the irradiation site, two or more ultraviolet irradiation devices along the flow direction of the laminated body and irradiation from a plurality of light sources are effective in effectively increasing the integrated light quantity. is there. In any case, it is preferable that the ultraviolet irradiation device 14 is configured to irradiate ultraviolet rays only to the laminate that passes immediately below.
  • the ultraviolet light source of the ultraviolet irradiation device 14 is not particularly limited, it has a light emission distribution at a wavelength of 400 nm or less.
  • a metal halide lamp or the like can be used.
  • a high pressure mercury lamp or a metal halide lamp having a large amount of light of 400 nm or less is preferably used as the ultraviolet light source in consideration of an absorption wavelength exhibited by a general polymerization initiator.
  • the irradiation amount in the wavelength region effective for activating the polymerization initiator is the integrated light amount (total energy irradiated to the laminate). It is preferable to irradiate with ultraviolet rays so as to be 100 to 1500 mJ / cm 2 . If the accumulated light amount is too small, the curing reaction of the UV curable adhesive will be insufficient, and sufficient adhesive strength will not be expressed. On the other hand, if the accumulated light amount is too large, the heat and adhesive emitted from the light source will be polymerized. The heat generated during the process may cause yellowing of the ultraviolet curable adhesive and deterioration of the polarizing film.
  • the film may be heated to a high temperature exceeding 150 ° C. due to heat generation. In this case, the polarizing film may be deteriorated.
  • it is effective to provide a plurality of ultraviolet irradiation devices along the film conveyance direction and to irradiate a plurality of times.
  • it may be preferable to set the irradiation amount from one ultraviolet irradiation device to 600 mJ / cm 2 or less in terms of the integrated light amount so that the above-mentioned integrated light amount of 100 to 1500 mJ / cm 2 is finally obtained. is there.
  • the illuminance meter 15 is preferably one that can measure the illuminance for each wavelength by dispersing the irradiated ultraviolet rays for each wavelength. It is possible to continuously produce a polarizing plate having sufficient adhesive strength by integrating the illuminance in the wavelength region necessary for the curing reaction, obtaining the integrated light amount, and managing the irradiation amount from the ultraviolet irradiation device 14 based on this. it can.
  • the line speed of the laminate in the ultraviolet irradiation step (C) is not particularly limited, but generally the line speed in the coating step (A) and the bonding step (B) is maintained almost as it is.
  • the coating step (A), the bonding step (B) and the ultraviolet irradiation step (C) have an emission wavelength in a wavelength region exceeding 400 nm, and a wavelength region of 250 to 400 nm. This is performed under LED (light emitting diode) illumination (D1) having no emission wavelength.
  • the LED illumination (D1) illuminates at least the coating means (A1), the bonding means (B1), and the ultraviolet irradiation means (C1).
  • An LED illumination (D1) having a light emission wavelength in a wavelength region exceeding 400 nm and not having a light emission wavelength in a wavelength region of 250 to 400 nm is a power monitor having a spectral function (for example, spectral radiation manufactured by Otsuka Electronics Co., Ltd.)
  • a spectral function for example, spectral radiation manufactured by Otsuka Electronics Co., Ltd.
  • an illuminance peak is observed in a wavelength region exceeding 400 nm, and 250 It is LED illumination in which the peak of illuminance is not seen in the wavelength range of ⁇ 400 nm.
  • LED lighting emits light when a voltage is applied to a PN junction composed of a P-type semiconductor and an N-type semiconductor called an LED chip, but the emission color is blue depending on the type of compound constituting the LED chip. (Around 450 nm), green (around 520 nm) or red (around 660 nm).
  • White LED lighting is a combination of blue light emission and yellow phosphor, which excites the phosphor from blue light emission to produce white light emission; a combination of blue light emission and red / green phosphor excites the phosphor.
  • White light emission by mixing blue, green and red light emission, and these LED illuminations have a light emission wavelength in the wavelength region exceeding 400 nm and have a wavelength of 250 to 400 nm.
  • LED lighting Since it does not have an emission wavelength in the wavelength range, it can be used as LED lighting (D1). In the combination of the LED chip and the phosphor, LED lighting whose LED chip emission wavelength is near 360 nm in the ultraviolet region or 405 nm is also being developed, but these have an emission wavelength of 400 nm or less. Therefore, it is not suitable for LED lighting (D1).
  • UV curing adhesive and optical film (or polarizing film) coated with UV curing adhesive can prevent the unintended curing reaction from progressing, and bonding process (B) and UV irradiation process (C) In this case, it is possible to suppress the unintended (not based on the ultraviolet irradiation device) curing reaction of the ultraviolet curable adhesive protruding from the end of the laminate. Thereby, the fall of the adhesive performance of the ultraviolet curable adhesive by a hardening reaction advancing before coating can be suppressed.
  • the UV curable adhesive that protrudes from the edge of the laminate adheres to the guide roll or the like, or the film such as an optical film breaks during the manufacturing process, and the applied UV curable adhesive scatters. Even when a manufacturing trouble such as this occurs, the adhesive attached to the guide roll or the like can be prevented from being cured, so that these adhesives can be easily removed with a solvent or the like. Thereby, even when the above manufacturing trouble occurs, the manufacturing process can be restored in a short time, and the polarizing plate can be manufactured without significantly reducing the operating rate of the manufacturing process. The obtained polarizing plate protrudes from the edge part of a laminated body, and there is little frequency which produces defects, such as a dent resulting from the hardened
  • the curing reaction of the ultraviolet curable adhesive proceeds only with the ultraviolet rays irradiated in the ultraviolet irradiation step (C)
  • the cumulative amount of ultraviolet rays from the ultraviolet irradiation device is used to irradiate the ultraviolet rays with the set cumulative amount of light.
  • the coating state of the adhesive on the film during the polarizing plate manufacturing process can be clearly confirmed by visual observation. It is also advantageous for detection.
  • an ultraviolet cut fluorescent lamp in which an ultraviolet cut filter is installed in a general fluorescent lamp, an illuminance peak of 400 nm or less can be cut. It is very difficult to visually confirm the coating state of the adhesive on the film during the process.
  • the installation position of the LED illumination (D1) is not particularly limited as long as it can illuminate all of the coating means (A1), the bonding means (B1), and the ultraviolet irradiation means (C1), and the polarizing plate manufacturing apparatus is installed.
  • the polarizing plate manufacturing facility may be installed above (for example, the ceiling), or the polarizing plate manufacturing apparatus itself may be equipped with the LED illumination (D1), or both. Good.
  • the polarizing plate manufacturing apparatus of the present invention itself includes LED illumination (D1).
  • the polarizing plate manufacturing apparatus accommodates the coating means (A1), the bonding means (B1), and the ultraviolet irradiation means (C1) (coating process ( A), one or more chambers (covering the periphery of the manufacturing process part in which the bonding step (B) and the ultraviolet irradiation step (C) are performed) can be provided, and one or more LED illuminations (D1) in this chamber Can be installed.
  • a total of four chambers each accommodating two coating means (A1), one bonding means (B1), and one ultraviolet irradiation means (C1) are provided.
  • One LED illumination (D1) (LED illumination 40, 41, 42, 43) is provided in each of the two chambers. From the viewpoint of effective use of the work space, it is preferable that the LED illumination (D1) be installed above (for example, the ceiling) or laterally (side of the chamber) in the chamber.
  • a coating means (A1), a bonding means (B1), and an ultraviolet irradiation means (C1) are accommodated in the polarizing plate manufacturing apparatus (the coating process (A), the bonding process (B), and the ultraviolet irradiation process (C)
  • the coating process (A), the bonding process (B), and the ultraviolet irradiation process (C) In the case where a chamber is provided that covers the periphery of the manufacturing process portion where the manufacturing process is performed) and the LED illumination (D1) is installed in the chamber, the illumination of the polarizing plate manufacturing facility (factory) is not necessarily LED. There is no need for illumination (D1).
  • an uncured ultraviolet curable adhesive may be brought into the subsequent process of the ultraviolet irradiation process (C). Therefore, the steps from the ultraviolet irradiation step (C) to the winding of the polarizing plate 4 by the winding roll 30 are also performed under the LED illumination (D1) so that the adhesive can be easily removed even in such a case. It is preferable to do.
  • the polarizing plate manufacturing apparatus for manufacturing the polarizing plate has the configuration shown in FIG. 1 and is used for bonding the polarizing film 1 and the first optical film 2.
  • an adhesive and an adhesive used for adhesion between the polarizing film 1 and the second optical film 3 an epoxy-based ultraviolet curable adhesive that contains an epoxy compound and a photopolymerization initiator and substantially does not contain a solvent.
  • the first optical film 2 a biaxially oriented cycloolefin resin film [obtained from Nippon Zeon Co., Ltd.] having a thickness of 60 ⁇ m and a width of 1330 mm is used as the second optical film 3.
  • a second coating machine 12 (“Microchamber Doctor” manufactured by Fuji Machine Co., Ltd.) provided with a gravure roll 12 is used.
  • the UV curable adhesive was applied so that the thickness of the adhesive layer was 3.5 ⁇ m [Coating process (A)].
  • the respective adhesive-coated surfaces of the first optical film 2 and the second optical film 3 coated with the ultraviolet curable adhesive are superposed on the polarizing film 1, and 240 N / O is applied by the nip rolls 20 and 21 for bonding. Clamped with a linear pressure of cm [bonding step (B)].
  • the laminated body after passing through the nip rolls 20 and 21 is irradiated with ultraviolet rays from the ultraviolet irradiation device 14 to cure the ultraviolet curing type [ultraviolet irradiation step (C)], and the obtained polarizing plate 4 is wound. It was wound up on a take-up roll 30.
  • the ultraviolet irradiation device 14 two ultraviolet lamps “EHAN1700NAL high-pressure mercury lamp” manufactured by GS Yuasa Co., Ltd. were used. The cumulative amount of ultraviolet light was 330 mJ / cm 2 for the two lamps.
  • the ceiling of the four chambers covering the periphery of the manufacturing process part where the coating process (A), the bonding process (B), and the ultraviolet irradiation process (C) are performed has emission wavelengths in a wavelength region exceeding 400 nm respectively.
  • LED lighting 40, 41, 42, 43 having no emission wavelength in the wavelength region of 250 to 400 nm is installed, and the coating process (A), the bonding process (B), and the ultraviolet irradiation process (C) are these It was carried out under LED lighting.
  • the illuminance spectrum of the LED lighting 40, 41, 42, 43 used is shown in FIG.
  • the illuminance spectrum of LED illumination is obtained by using a spectral irradiance measurement system “MCPD-3700” (detector 2480C) manufactured by Otsuka Electronics Co., Ltd. Measured in the wavelength range. Measurement conditions were such that the measured values were accumulated eight times with a light capture time of 400 milliseconds. Illuminance (W / min / nm) at each wavelength for every 1 nm was obtained. It was confirmed that the LED illumination used in this example does not have an emission wavelength in the wavelength range of 250 to 400 nm.
  • Example 1 A polarizing plate was produced in the same manner as in Example 1 except that instead of the LED illumination in Example 1, an ultraviolet cut fluorescent lamp having no emission wavelength in the wavelength range of 250 to 400 nm was used. The illuminance spectrum of the ultraviolet cut fluorescent lamp used is shown in FIG.
  • Example 2 A polarizing plate was produced in the same manner as in Example 1 except that a fluorescent lamp having an emission wavelength in the vicinity of 365 nm was used instead of the LED illumination in Example 1. The illuminance spectrum of the fluorescent lamp used is shown in FIG.
  • Example 1 and Comparative Example 2 the coating state of the adhesive layer end could be easily visually observed, but in Comparative Example 1, it was not visually observed.
  • Example 1 In Example 1 and Comparative Example 1, there was no adhesive solidifying component, and the adhesive could be easily removed. On the other hand, in Comparative Example 2, the shape of the adhesive droplet remained even after wiping, and this could not be removed.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Polarising Elements (AREA)
  • Liquid Crystal (AREA)
  • Laminated Bodies (AREA)
  • Adhesives Or Adhesive Processes (AREA)

Abstract

Provided is a polarizing plate fabrication method comprising the following steps: a coating step (A) in which the bonding surface of at least either a polarizing film or an optical film is coated with an ultraviolet curing-type adhesive agent; a bonding step (B) that superimposes the polarizing film and the optical film with the ultraviolet curing type adhesive agent disposed therebetween to produce a laminated body; and an ultraviolet light irradiating step (C) in which the laminated body is exposed to ultraviolet light to harden the ultraviolet curing-type adhesive agent. The coating step (A), the bonding step (B), and the ultraviolet light irradiating step (C) are performed under LED lighting that has luminescence wavelengths in a wavelength range that exceeds 400 nm and that does not have luminescence wavelengths in the wavelength range of 250-400 nm. Also provided is a polarizing plate fabrication apparatus that can execute the fabrication process in an optimal manner.

Description

偏光板の製造方法および製造装置Polarizing plate manufacturing method and manufacturing apparatus
　本発明は、液晶表示部材として使用される偏光板の製造方法および製造装置に関する。 The present invention relates to a manufacturing method and a manufacturing apparatus of a polarizing plate used as a liquid crystal display member.
　液晶表示装置の中核をなす液晶パネルは通常、液晶セルの両面に偏光板を配置して構成される。一般に偏光板は、ポリビニルアルコール系樹脂からなる偏光フィルムの一方の面に、接着剤を介して透明樹脂からなる保護フィルムが貼合された構造になっている。偏光フィルムのもう一方の面にも、接着剤を介して透明樹脂フィルムを貼合することが多く、こちら側の透明樹脂フィルムは、反対側の保護フィルムと同様、偏光フィルムに対する保護機能のみを有するもののほか、保護機能に加えて、液晶セルの光学補償や視野角補償を目的に、面内および／または厚み方向の位相差が付与されたいわゆる位相差フィルムであることもある。本明細書では、偏光フィルムに接着剤を介して貼合されるこのような保護フィルムや位相差フィルムなどを、「光学フィルム」と呼ぶことにする。偏光フィルムへの光学フィルムの貼合に用いられる接着剤は、一般に液状のものであり、その液状接着剤の硬化反応により、偏光フィルムと光学フィルムとの間で接着力を発現する。 The liquid crystal panel that forms the core of a liquid crystal display device is usually configured by disposing polarizing plates on both sides of a liquid crystal cell. Generally, a polarizing plate has a structure in which a protective film made of a transparent resin is bonded to one surface of a polarizing film made of a polyvinyl alcohol resin through an adhesive. A transparent resin film is often bonded to the other surface of the polarizing film via an adhesive, and the transparent resin film on this side has only a protective function for the polarizing film, similar to the protective film on the opposite side. In addition to the protective function, it may be a so-called retardation film provided with an in-plane and / or thickness direction retardation for the purpose of optical compensation and viewing angle compensation of the liquid crystal cell. In this specification, such a protective film or retardation film bonded to a polarizing film via an adhesive is referred to as an “optical film”. The adhesive used for bonding the optical film to the polarizing film is generally a liquid, and exhibits an adhesive force between the polarizing film and the optical film by the curing reaction of the liquid adhesive.
　近年、テレビをはじめとする液晶表示装置の価格低下が激しく、それを構成する部材への低価格化の要求が強くなる一方で、品質への要求も一層強くなってきている。この流れの中で、偏光板の製造に用いられる接着剤も、適用できる光学フィルムの種類がセルロース系樹脂フィルムなど特定の樹脂フィルムに限られる水系接着剤から、適用できる光学フィルムの種類が多い活性エネルギー線硬化型接着剤へと変更されつつある。活性エネルギー線硬化型接着剤を用いた偏光フィルムと光学フィルムの貼合は、たとえば、特開２００４－２４５９２５号公報（特許文献１）に提案されている。 In recent years, the price of liquid crystal display devices such as televisions has been drastically decreasing, and the demand for lower prices for the components constituting the same has increased, while the demand for quality has also increased. In this trend, adhesives used in the manufacture of polarizing plates are also active with many types of optical films that can be applied, from aqueous adhesives where the types of optical films that can be applied are limited to specific resin films such as cellulose resin films. The energy ray curable adhesive is being changed. The pasting of a polarizing film and an optical film using an active energy ray-curable adhesive has been proposed in, for example, Japanese Patent Application Laid-Open No. 2004-245925 (Patent Document 1).
　活性エネルギー線硬化型接着剤は液状で用意され、被塗布物にその液状接着剤を直接塗布するダイコーターや、表面に形成された凹溝に液状接着剤を担持してそれを被塗布物表面に転写するグラビアロールを用いて、光学フィルムの偏光フィルムへの貼合面に予め塗工される。そして、その接着剤塗工面に偏光フィルムを重ね、紫外線や電子線などの活性エネルギー線を照射し、接着剤を硬化させて、接着力が発現される。このような活性エネルギー線硬化型接着剤を用いる方式は、適用できる光学フィルムが多く、非常に有効な方法である。 The active energy ray curable adhesive is prepared in liquid form, and the die coater that directly applies the liquid adhesive to the object to be coated, or the liquid adhesive that is supported on the groove formed on the surface, is applied to the surface of the object to be coated. Using a gravure roll that is transferred to the optical film, the optical film is preliminarily applied to the bonding surface to the polarizing film. And the polarizing film is piled up on the adhesive coating surface, active energy rays, such as an ultraviolet-ray and an electron beam, are irradiated, an adhesive agent is hardened, and adhesive force is expressed. The method using such an active energy ray-curable adhesive is a very effective method because there are many applicable optical films.
　活性エネルギー線硬化型接着剤を用いた偏光板の製造方法として、たとえば、特開２００９－１３４１９０号公報（特許文献２）には、偏光フィルムの両面にそれぞれ接着剤を介して保護フィルムを重ね合わせて積層体を得、この積層体の搬送方向に沿って円弧状に形成された凸曲面の外表面にその積層体を密着させながら活性エネルギー線を照射する方法が開示されている。この方法によれば、得られる偏光板に発生しやすい逆カールおよびウエーブカールを抑制でき、良好な性能を有する偏光板を製造できる。 As a method for producing a polarizing plate using an active energy ray-curable adhesive, for example, in JP 2009-134190 A (Patent Document 2), a protective film is laminated on both surfaces of a polarizing film via an adhesive. Thus, a method is disclosed in which a laminate is obtained, and active energy rays are irradiated while the laminate is brought into close contact with the outer surface of a convex curved surface formed in an arc shape along the conveying direction of the laminate. According to this method, the reverse curl and wave curl that are likely to occur in the obtained polarizing plate can be suppressed, and a polarizing plate having good performance can be produced.
特開２００４－２４５９２５号公報JP 2004-245925 A 特開２００９－１３４１９０号公報JP 2009-134190 A
　活性エネルギー線として紫外線を利用する場合、エネルギーの高い４００ｎｍ以下の短波長域の紫外線を利用することが一般的である。用いる接着剤もこの波長域で反応を起こし、硬化反応を生じるものが一般的に用いられる。この紫外線硬化型接着剤によれば、偏光フィルムと光学フィルムとの間の接着性が良好な偏光板を製造することができるが、上記波長域の紫外線で硬化するために、偏光板製造施設（工場）内や該施設内に設置される偏光板製造装置が有する水銀灯または蛍光灯等の照明によっても硬化することが考えられる。 When ultraviolet rays are used as active energy rays, it is common to use ultraviolet rays having a high energy and a short wavelength region of 400 nm or less. As the adhesive to be used, an adhesive that reacts in this wavelength region and causes a curing reaction is generally used. According to this ultraviolet curable adhesive, it is possible to produce a polarizing plate with good adhesion between the polarizing film and the optical film, but in order to cure with ultraviolet rays in the above wavelength range, It can be considered that the film is cured by illumination such as a mercury lamp or a fluorescent lamp included in the polarizing plate manufacturing apparatus installed in the factory or in the facility.
　偏光板製造装置の接着剤塗工手段には、使用（塗工）前の紫外線硬化型接着剤が準備されている。このような使用前の紫外線硬化型接着剤において、上記照明からの紫外線照射により意図しない硬化反応が生じると、接着性能が低下するおそれがある。 The UV curable adhesive before use (coating) is prepared for the adhesive coating means of the polarizing plate manufacturing apparatus. In such an ultraviolet curable adhesive before use, if an unintended curing reaction is caused by the ultraviolet irradiation from the illumination, the adhesive performance may be deteriorated.
　また、偏光板製造においては、紫外線硬化型接着剤が塗工された偏光フィルムまたは光学フィルムの端面や、塗工された紫外線硬化型接着剤を介して偏光フィルムと光学フィルムとを重ね合わせて得られる積層体の端面から未硬化の紫外線硬化型接着剤がはみ出し、これがフィルムを搬送するガイドロール等に付着することがあり得る。この場合、ガイドロール等に付着した未硬化の紫外線硬化型接着剤において、上記照明からの紫外線照射により意図しない硬化反応が生じると、ガイドロール等に付着した紫外線硬化型接着剤を除去して製造工程を復旧させるのに多大な時間を要し、製造工程の稼働率が著しく低下する。 In the production of polarizing plates, the polarizing film and the optical film are overlapped with the end face of the polarizing film or optical film coated with the ultraviolet curable adhesive or the coated ultraviolet curable adhesive. An uncured ultraviolet curable adhesive may protrude from the end face of the laminate to be adhered to a guide roll or the like that transports the film. In this case, in the uncured UV curable adhesive attached to the guide roll, etc., when an unintended curing reaction occurs due to the UV irradiation from the illumination, the UV curable adhesive attached to the guide roll etc. is removed and manufactured. It takes a lot of time to restore the process, and the operating rate of the manufacturing process is significantly reduced.
　本発明の目的は、偏光フィルムに紫外線硬化型接着剤を介して光学フィルムを貼合する偏光板の製造において、意図しない紫外線硬化型接着剤の硬化を防止し、もって偏光フィルムと光学フィルムとの間の接着性が良好である偏光板を、製造工程の稼働率を著しく低下させることなく効率良く製造できる方法を提供することにある。また本発明の他の目的は、上記のような偏光板の製造方法を好適に実施できる偏光板製造装置を提供することにある。 An object of the present invention is to prevent unintentional curing of an ultraviolet curable adhesive in the production of a polarizing plate in which an optical film is bonded to a polarizing film via an ultraviolet curable adhesive. An object of the present invention is to provide a method for efficiently producing a polarizing plate having good adhesiveness without significantly reducing the operating rate of the production process. Moreover, the other object of this invention is to provide the polarizing plate manufacturing apparatus which can implement suitably the manufacturing method of the above polarizing plates.
　本発明者らは、上記課題を解決するべく鋭意研究を行なった結果、偏光板製造施設（工場）内や該施設内に設置される偏光板製造装置が有する照明として、特定の発光波長を有するＬＥＤ照明を用いることにより、偏光フィルムと光学フィルムとを貼合する際に使用される紫外線硬化型接着剤の硬化反応を、紫外線照射手段を用いた紫外線照射工程のみで行なわせ、該工程以外での意図しない硬化反応を抑制できることを見出し、本発明を完成するに至った。 As a result of diligent research to solve the above-mentioned problems, the present inventors have a specific emission wavelength as illumination of a polarizing plate manufacturing facility (factory) or a polarizing plate manufacturing apparatus installed in the facility. By using LED illumination, the curing reaction of the ultraviolet curable adhesive used when laminating the polarizing film and the optical film is performed only in the ultraviolet irradiation process using the ultraviolet irradiation means, and other than this process. The present inventors have found that an unintended curing reaction can be suppressed and have completed the present invention.
　すなわち本発明は以下のものを含む。
　［１］　ポリビニルアルコール系樹脂からなる偏光フィルムに、紫外線硬化型接着剤を介して熱可塑性樹脂からなる光学フィルムを貼合して、偏光板を製造する方法であって、
　（Ａ）前記偏光フィルムおよび前記光学フィルムの少なくとも一方の貼合面に前記紫外線硬化型接着剤を塗工する塗工工程、
　（Ｂ）塗工された前記紫外線硬化型接着剤を介して前記偏光フィルムと前記光学フィルムとを重ね合わせて積層体を得る貼合工程、および
　（Ｃ）前記積層体に紫外線を照射して前記紫外線硬化型接着剤を硬化させる紫外線照射工程
を含み、
　前記塗工工程（Ａ）、前記貼合工程（Ｂ）および前記紫外線照射工程（Ｃ）が、４００ｎｍを超える波長域に発光波長を有し、２５０～４００ｎｍの波長域に発光波長を有しないＬＥＤ照明のもとで実施される偏光板の製造方法。 That is, the present invention includes the following.
[1] A method of manufacturing a polarizing plate by laminating an optical film made of a thermoplastic resin to a polarizing film made of a polyvinyl alcohol resin through an ultraviolet curable adhesive,
(A) a coating step of applying the ultraviolet curable adhesive to at least one bonding surface of the polarizing film and the optical film;
(B) A laminating step of obtaining a laminate by superimposing the polarizing film and the optical film through the coated ultraviolet curable adhesive, and (C) irradiating the laminate with ultraviolet rays, Including an ultraviolet irradiation step of curing the ultraviolet curable adhesive;
LED in which the coating step (A), the bonding step (B), and the ultraviolet irradiation step (C) have a light emission wavelength in a wavelength region exceeding 400 nm and no light emission wavelength in a wavelength region of 250 to 400 nm A method for producing a polarizing plate carried out under illumination.
　［２］　前記塗工工程（Ａ）、前記貼合工程（Ｂ）および前記紫外線照射工程（Ｃ）が実施される１以上のチャンバ内に設けられた前記ＬＥＤ照明のもとで、前記塗工工程（Ａ）、前記貼合工程（Ｂ）および前記紫外線照射工程（Ｃ）が実施される、［１］に記載の偏光板の製造方法。 [2] Under the LED illumination provided in one or more chambers in which the coating step (A), the bonding step (B), and the ultraviolet irradiation step (C) are performed, the coating step is performed. The manufacturing method of the polarizing plate as described in [1] in which a process (A), the said bonding process (B), and the said ultraviolet irradiation process (C) are implemented.
　［３］　ポリビニルアルコール系樹脂からなる偏光フィルムに、紫外線硬化型接着剤を介して熱可塑性樹脂からなる光学フィルムを貼合して、偏光板を製造するための装置であって、
　（Ａ１）前記偏光フィルムおよび前記光学フィルムの少なくとも一方の貼合面に前記紫外線硬化型接着剤を塗工するための塗工手段、
　（Ｂ１）塗工された前記紫外線硬化型接着剤を介して前記偏光フィルムと光学フィルムとを重ね合わせて積層体を得るための貼合手段、
　（Ｃ１）前記積層体に紫外線を照射して前記紫外線硬化型接着剤を硬化させるための紫外線照射手段、および
　（Ｄ１）前記塗工手段（Ａ１）、前記貼合手段（Ｂ１）および前記紫外線照射手段（Ｃ１）を照明するための、４００ｎｍを超える波長域に発光波長を有し、２５０～４００ｎｍの波長域に発光波長を有しないＬＥＤ照明
を備える偏光板製造装置。 [3] An apparatus for producing a polarizing plate by laminating an optical film made of a thermoplastic resin to a polarizing film made of a polyvinyl alcohol resin through an ultraviolet curable adhesive,
(A1) Coating means for applying the ultraviolet curable adhesive to at least one bonding surface of the polarizing film and the optical film,
(B1) A bonding means for obtaining a laminate by superimposing the polarizing film and the optical film via the coated ultraviolet curable adhesive,
(C1) Ultraviolet irradiation means for irradiating the laminate with ultraviolet rays to cure the ultraviolet curable adhesive, and (D1) The coating means (A1), the bonding means (B1), and the ultraviolet irradiation. An apparatus for producing a polarizing plate, comprising: LED illumination for illuminating the means (C1), having an emission wavelength in a wavelength range exceeding 400 nm and no emission wavelength in a wavelength range of 250 to 400 nm.
　［４］　前記塗工手段（Ａ１）、前記貼合手段（Ｂ１）および前記紫外線照射手段（Ｃ１）を収容するための１以上のチャンバをさらに備え、
　前記チャンバ内に前記ＬＥＤ照明（Ｄ１）が設置される［３］に記載の偏光板製造装置。 [4] It further comprises one or more chambers for accommodating the coating means (A1), the bonding means (B1), and the ultraviolet irradiation means (C1),
The polarizing plate manufacturing apparatus according to [3], wherein the LED illumination (D1) is installed in the chamber.
　本発明によれば、偏光フィルムと光学フィルムとを貼合する際に使用される紫外線硬化型接着剤の硬化反応を、紫外線照射手段を用いた紫外線照射工程のみで行なわせることができるため、使用前の紫外線硬化型接着剤の意図しない硬化反応や、ガイドロール等に付着した未硬化の紫外線硬化型接着剤の意図しない硬化反応を効果的に抑制することができる。したがって、偏光フィルムと光学フィルムとの間の接着性が良好である偏光板を、製造工程の稼働率を著しく低下させることなく効率良く製造することができる。 According to the present invention, since the curing reaction of the ultraviolet curable adhesive used when laminating the polarizing film and the optical film can be performed only in the ultraviolet irradiation process using the ultraviolet irradiation means, The unintended curing reaction of the previous ultraviolet curable adhesive and the unintended curing reaction of the uncured ultraviolet curable adhesive attached to the guide roll or the like can be effectively suppressed. Therefore, a polarizing plate having good adhesion between the polarizing film and the optical film can be efficiently produced without significantly reducing the operating rate of the production process.
　またＬＥＤ照明を使用するので、偏光板製造工程中におけるフィルム上の接着剤の塗工状態を目視で明瞭に確認することができ、接着剤の塗工状態の不具合を目視検知するうえでも有利である。 Moreover, since LED lighting is used, the coating state of the adhesive on the film during the polarizing plate manufacturing process can be clearly confirmed visually, which is advantageous for visually detecting defects in the coating state of the adhesive. is there.
本発明の偏光板製造装置の一例を示す概略側面図である。It is a schematic side view which shows an example of the polarizing plate manufacturing apparatus of this invention. 実施例１で用いたＬＥＤ照明の照度スペクトルである。It is an illumination intensity spectrum of LED illumination used in Example 1. FIG. 比較例１で用いた紫外線カット蛍光灯の照度スペクトルである。It is an illuminance spectrum of the ultraviolet cut fluorescent lamp used in Comparative Example 1. 比較例２で用いた蛍光灯の照度スペクトルである。It is an illumination intensity spectrum of the fluorescent lamp used in Comparative Example 2.
　本発明では、ポリビニルアルコール系樹脂からなる偏光フィルムに、紫外線硬化型接着剤を介して熱可塑性樹脂からなる光学フィルムを貼合し、偏光板を製造する。光学フィルムは、偏光フィルムの片面にのみ貼合してもよいし、偏光フィルムの両面に貼合してもよい。 In the present invention, an optical film made of a thermoplastic resin is bonded to a polarizing film made of a polyvinyl alcohol resin through an ultraviolet curable adhesive to produce a polarizing plate. The optical film may be bonded only to one side of the polarizing film, or may be bonded to both sides of the polarizing film.
　［偏光フィルム］
　偏光フィルムは、ポリビニルアルコール系樹脂からなり、そのフィルムに入射する光のうち、ある方向の振動面を有する光を透過し、それと直交する振動面を有する光を吸収する性質を有するフィルムであり、典型的には、ポリビニルアルコール系樹脂に二色性色素が吸着配向しているフィルムである。 [Polarized film]
The polarizing film is made of polyvinyl alcohol-based resin, and is a film having a property of transmitting light having a vibration surface in a certain direction among light incident on the film and absorbing light having a vibration surface perpendicular thereto. Typically, it is a film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin.
　偏光フィルムを構成するポリビニルアルコール系樹脂は、ポリ酢酸ビニル系樹脂をケン化することにより得られる。ポリビニルアルコール系樹脂の原料となるポリ酢酸ビニル系樹脂は、酢酸ビニルの単独重合体であるポリ酢酸ビニルのほか、酢酸ビニルおよびこれと共重合可能な他の単量体との共重合体であってもよい。 The polyvinyl alcohol resin constituting the polarizing film can be obtained by saponifying a polyvinyl acetate resin. The polyvinyl acetate resin used as a raw material for the polyvinyl alcohol resin is not only polyvinyl acetate, which is a homopolymer of vinyl acetate, but also a copolymer of vinyl acetate and other monomers copolymerizable therewith. May be.
　ポリビニルアルコール系樹脂からなるフィルムに、一軸延伸処理、二色性色素による染色処理、および染色後のホウ酸架橋処理を施すことによって、偏光フィルムが得られる。二色性色素としては、ヨウ素や二色性の有機染料が用いられる。一軸延伸は、二色性色素による染色の前に行なってもよいし、二色性色素による染色と同時に行なってもよいし、二色性色素による染色の後、たとえばホウ酸架橋処理中に行なってもよい。 A polarizing film is obtained by subjecting a film made of polyvinyl alcohol resin to uniaxial stretching treatment, dyeing treatment with a dichroic dye, and boric acid crosslinking treatment after dyeing. As the dichroic dye, iodine or a dichroic organic dye is used. Uniaxial stretching may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing with a dichroic dye, or after dyeing with a dichroic dye, for example, during a boric acid crosslinking treatment. May be.
　かくして製造され、二色性色素が吸着配向しているポリビニルアルコール系樹脂からなる偏光フィルムが、偏光板の原料の一つとなる。 A polarizing film made of a polyvinyl alcohol-based resin thus manufactured and having a dichroic dye adsorbed and oriented is one of the raw materials for the polarizing plate.
　［光学フィルム］
　偏光フィルムに、熱可塑性樹脂からなる光学フィルムを貼合し、偏光板を製造する。光学フィルムは、温度２０℃でＤ線により測定される屈折率が１．４～１．７の範囲にあることが好ましい。光学フィルムの屈折率は、ＪＩＳ　Ｋ　００６２：１９９２「化学製品の屈折率測定方法」に準拠して測定される。光学フィルムがこの範囲の屈折率を有すれば、製造される偏光板を液晶パネルに組み込んだときの表示特性に優れたものとなる。同様な理由で光学フィルムの好ましい屈折率は、１．４５～１．６７の範囲である。 [Optical film]
An optical film made of a thermoplastic resin is bonded to the polarizing film to produce a polarizing plate. The optical film preferably has a refractive index measured by D-ray at a temperature of 20 ° C. in the range of 1.4 to 1.7. The refractive index of the optical film is measured according to JIS K 0062: 1992 “Method for measuring refractive index of chemical product”. If the optical film has a refractive index in this range, it will have excellent display characteristics when the produced polarizing plate is incorporated in a liquid crystal panel. For the same reason, the preferred refractive index of the optical film is in the range of 1.45 to 1.67.
　光学フィルムは、そのヘーズ値が０．００１～１０％程度の範囲にあることが、得られる偏光板のコントラストを向上させ、特に液晶パネルに組み込んで黒表示としたときに、輝度低下などの不具合を生じる可能性が少なくなることから、好ましい。ヘーズ値は、（拡散透過率／全光線透過率）×１００（％）で定義される値であって、ＪＩＳ　Ｋ　７１３６：２０００「プラスチック－透明材料のヘーズの求め方」に準拠して測定される。 The optical film has a haze value in the range of about 0.001 to 10%, which improves the contrast of the obtained polarizing plate, particularly when it is incorporated into a liquid crystal panel to display black and has a problem such as a decrease in luminance. This is preferable because the possibility of occurrence of is reduced. The haze value is a value defined by (diffuse transmittance / total light transmittance) × 100 (%), and is measured in accordance with JIS K 7136: 2000 “How to determine haze of plastic and transparent material”. The
　光学フィルムを構成する熱可塑性樹脂として、たとえば次のようなものを挙げることができ、ここでは、温度２０℃でＤ線により測定される屈折率をｎD（２０℃）として併せて表示する。 Examples of the thermoplastic resin constituting the optical film include the following, and here, the refractive index measured by the D line at a temperature of 20 ° C. is also displayed as n D (20 ° C.).
　シクロオレフィン系樹脂〔ｎD（２０℃）＝１．５１～１．５４程度〕、
　結晶性ポリオレフィン系樹脂〔ｎD（２０℃）＝１．４６～１．５０程度〕、
　ポリエステル系樹脂〔ｎD（２０℃）＝１．５７～１．６６程度〕、
　ポリカーボネート系樹脂〔ｎD（２０℃）＝１．５７～１．５９程度〕、
　アクリル系樹脂〔ｎD（２０℃）＝１．４９～１．５１程度〕、
　トリアセチルセルロース系樹脂〔ｎD（２０℃）＝１．４８前後〕など。 Cycloolefin resin (n D (20 ° C.) = 1.51 to about 1.54),
Crystalline polyolefin resin [n D (20 ° C.) = 1.46 to 1.50 or so]
Polyester resin (n D (20 ° C.) = 1.57 to 1.66 or so),
Polycarbonate resin (n D (20 ° C.) = 1.57 to 1.59),
Acrylic resin [n D (20 ° C.) = 1.49 to about 1.51],
Triacetyl cellulose resin [n D (20 ° C.) = 1.48 or so].
　シクロオレフィン系樹脂は、ノルボルネンの如きシクロオレフィン系モノマーを主な構成単位とする重合体であって、シクロオレフィン系モノマーの開環重合体を水素添加して得られる樹脂、シクロオレフィン系モノマーと、エチレンやプロピレンの如き炭素数２～１０の鎖状オレフィン系モノマーおよび／またはスチレンの如き芳香族ビニルモノマーとの付加重合体などが包含される。 The cycloolefin resin is a polymer having a cycloolefin monomer such as norbornene as a main structural unit, a resin obtained by hydrogenating a ring-opening polymer of a cycloolefin monomer, a cycloolefin monomer, Examples include addition polymers with chain olefin monomers having 2 to 10 carbon atoms such as ethylene and propylene and / or aromatic vinyl monomers such as styrene.
　結晶性ポリオレフィン系樹脂は、炭素数２～１０の鎖状オレフィン系モノマーを主な構成単位とする重合体であって、鎖状オレフィン系モノマーの単独重合体、２種類以上の鎖状オレフィン系モノマーを用いた二元または三元以上の共重合体が包含される。具体的には、ポリエチレン系樹脂、ポリプロピレン系樹脂、エチレン－プロピレン共重合体、４－メチル－１－ペンテンの単独重合体、または４－メチル－１－ペンテンとエチレンもしくはプロピレンとの共重合体などが包含される。 The crystalline polyolefin resin is a polymer mainly composed of a chain olefin monomer having 2 to 10 carbon atoms, which is a homopolymer of a chain olefin monomer and two or more types of chain olefin monomers. Binary or ternary or higher copolymers using are included. Specifically, a polyethylene resin, a polypropylene resin, an ethylene-propylene copolymer, a homopolymer of 4-methyl-1-pentene, a copolymer of 4-methyl-1-pentene and ethylene or propylene, etc. Is included.
　ポリエステル系樹脂は、ポリエチレンテレフタレート系樹脂やポリエチレンナフタレート系樹脂の如き芳香族ポリエステルのほか、脂肪族ポリエステルも包含する。 Polyester resin includes aliphatic polyester as well as aromatic polyester such as polyethylene terephthalate resin and polyethylene naphthalate resin.
　ポリカーボネート系樹脂は、典型的にはビスフェノールＡとホスゲンとの反応によって得られ、主鎖にカーボネート結合－Ｏ－ＣＯ－Ｏ－を有する重合体である。 The polycarbonate resin is typically a polymer obtained by a reaction of bisphenol A and phosgene, and having a carbonate bond —O—CO—O— in the main chain.
　アクリル系樹脂は、典型的にはメタクリル酸メチルを主な構成単位とする重合体であって、メタクリル酸メチルの単独重合体のほか、メタクリル酸メチルと他のメタクリル酸エステルおよび／またはアクリル酸エステルとの共重合体なども包含される。 The acrylic resin is typically a polymer mainly composed of methyl methacrylate. In addition to a methyl methacrylate homopolymer, methyl methacrylate and other methacrylate esters and / or acrylic esters. And copolymers thereof are also included.
　トリアセチルセルロース系樹脂は、セルロースの酢酸エステルである。
　これらの熱可塑性樹脂から、溶剤キャスト法や溶融押出法などによってフィルムに製膜し、本発明に用いる光学フィルムとすることができる。また、製膜後さらに一軸または二軸に延伸したものを、本発明に用いる光学フィルムとすることもできる。光学フィルムは偏光フィルムへの貼合に先立って、その貼合面に、ケン化処理、コロナ処理、プラズマ処理、プライマー処理またはアンカーコーティング処理の如き、易接着処理が施されてもよい。また、光学フィルムの偏光フィルムへの貼合面と反対側の面に、ハードコート層、反射防止層または防眩層の如き、各種の処理層を設けてもよい。 Triacetyl cellulose resin is an acetate of cellulose.
From these thermoplastic resins, a film can be formed into a film by a solvent casting method, a melt extrusion method, or the like to obtain an optical film used in the present invention. Moreover, what was extended | stretched further uniaxially or biaxially after film forming can also be made into the optical film used for this invention. Prior to bonding to the polarizing film, the optical film may be subjected to easy adhesion treatment such as saponification treatment, corona treatment, plasma treatment, primer treatment or anchor coating treatment. Moreover, you may provide various process layers like a hard-coat layer, an antireflection layer, or an anti-glare layer in the surface on the opposite side to the bonding surface to the polarizing film of an optical film.
　光学フィルムは、通常５～２００μｍ程度の厚さを有することが好ましい。光学フィルムが薄すぎると、ハンドリング性に欠け、偏光板製造ライン中で破断したり、皺の発生を誘発したりする可能性が高くなる。一方、厚すぎると、得られる偏光板が厚くなり、重量も大きくなることから、商品性を損なうことがある。これらの理由から、光学フィルムのより好ましい厚さは１０～１２０μｍ、さらに好ましい厚さは１０～８５μｍである。 The optical film preferably has a thickness of usually about 5 to 200 μm. If the optical film is too thin, the handling property is lacking, and there is a high possibility that the optical film will be broken in the polarizing plate production line or cause wrinkles. On the other hand, if it is too thick, the resulting polarizing plate becomes thick and the weight increases, which may impair the commercial properties. For these reasons, a more preferable thickness of the optical film is 10 to 120 μm, and a more preferable thickness is 10 to 85 μm.
　［紫外線硬化型接着剤］
　偏光フィルムに光学フィルムを貼合するにあたり、まず偏光フィルムおよび光学フィルムの少なくとも一方の貼合面に紫外線硬化型接着剤を塗工する。典型的には光学フィルムの偏光フィルムへの貼合面に紫外線硬化型接着剤を塗工する。紫外線硬化型接着剤の厚さは、好ましくは０．５～５μｍの範囲である。その厚さが０．５μｍを下回ると、接着強度にムラが生じることがある。一方、その厚さが５μｍを超えると、製造コストが増大するだけでなく、接着剤の種類によっては偏光板の色相に影響することもある。上記の範囲内で比較的厚め、たとえば３．５μｍ以上、とりわけ４μｍ以上とすれば、その厚さが多少変動しても、それに起因する気泡などの欠陥が現れにくくなるが、一方で、このように厚くすることはコストの増加につながりかねないので、可能な範囲で薄くすることが望まれる。これらの理由から、接着剤の好ましい厚さは、１～４μｍ、さらには１．５～３．５μｍの範囲である。 [UV curable adhesive]
When bonding an optical film to a polarizing film, first, an ultraviolet curable adhesive is applied to at least one bonding surface of the polarizing film and the optical film. Typically, an ultraviolet curable adhesive is applied to the bonding surface of the optical film to the polarizing film. The thickness of the ultraviolet curable adhesive is preferably in the range of 0.5 to 5 μm. If the thickness is less than 0.5 μm, uneven adhesion strength may occur. On the other hand, when the thickness exceeds 5 μm, not only the manufacturing cost increases, but also the hue of the polarizing plate may be affected depending on the kind of the adhesive. If the thickness is relatively large within the above range, for example, 3.5 μm or more, especially 4 μm or more, even if the thickness slightly varies, defects such as bubbles are less likely to appear. Since increasing the thickness may lead to an increase in cost, it is desirable to reduce the thickness as much as possible. For these reasons, the preferred thickness of the adhesive is in the range of 1 to 4 μm, more preferably 1.5 to 3.5 μm.
　紫外線硬化型接着剤は、液状の塗布可能な状態で供給される限りにおいて、従来から偏光板の製造に使用されている各種のものであることができるが、耐候性や重合性などの観点から、カチオン重合性の化合物、たとえばエポキシ化合物、より具体的には、先の特許文献１（特開２００４－２４５９２５号公報）に記載されるような、分子内に芳香環を有しないエポキシ化合物を、紫外線硬化性成分の一つとして含有する接着剤が好ましい。 As long as the UV curable adhesive is supplied in a liquid coatable state, it can be any of those conventionally used in the production of polarizing plates, but from the viewpoint of weather resistance, polymerizability, etc. A cationically polymerizable compound such as an epoxy compound, more specifically, an epoxy compound having no aromatic ring in the molecule, as described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-245925). An adhesive contained as one of the ultraviolet curable components is preferred.
　上記エポキシ化合物は、たとえば、ビスフェノールＡのジグリシジルエーテルを代表例とする芳香族エポキシ化合物の原料である芳香族ポリヒドロキシ化合物を核水添し、それをグリシジルエーテル化して得られる水素化エポキシ化合物、脂環式環に結合するエポキシ基を分子内に少なくとも１個有する脂環式エポキシ化合物、脂肪族ポリヒドロキシ化合物のグリシジルエーテルを代表例とする脂肪族エポキシ化合物などであることができる。 The epoxy compound is, for example, a hydrogenated epoxy compound obtained by nuclear hydrogenation of an aromatic polyhydroxy compound which is a raw material of an aromatic epoxy compound represented by diglycidyl ether of bisphenol A and glycidyl ether. Examples thereof include an alicyclic epoxy compound having at least one epoxy group bonded to the alicyclic ring in the molecule, and an aliphatic epoxy compound typified by a glycidyl ether of an aliphatic polyhydroxy compound.
　また、紫外線硬化型接着剤には、エポキシ化合物を代表例とするカチオン重合性化合物のほか、通常は重合開始剤、特に紫外線の照射によりカチオン種またはルイス酸を発生し、カチオン重合性化合物の重合を開始させるための光カチオン重合開始剤が配合される。さらに、加熱によって重合を開始させる熱カチオン重合開始剤、その他、光増感剤などの各種添加剤が配合されていてもよい。 In addition to cationically polymerizable compounds, typically epoxy compounds, UV curable adhesives usually generate polymerization initiators, especially cationic species or Lewis acids upon irradiation with ultraviolet rays, and polymerize cationically polymerizable compounds. A photocationic polymerization initiator for initiating the reaction is blended. Further, a thermal cationic polymerization initiator that initiates polymerization by heating, and various other additives such as a photosensitizer may be blended.
　偏光フィルムの両面に光学フィルムを貼合する場合、それぞれの光学フィルムに適用される紫外線硬化型接着剤は、同じであっても異なっていてもよいが、生産性の観点からは、適度の接着力が得られるという前提で、両面とも同じ紫外線硬化型接着剤とするほうが好ましい。 When the optical film is bonded to both sides of the polarizing film, the ultraviolet curable adhesive applied to each optical film may be the same or different, but from the viewpoint of productivity, moderate adhesion It is preferable to use the same UV curable adhesive on both sides on the premise that strength can be obtained.
　［偏光板の製造方法および偏光板製造装置］
　本発明では、以上説明したポリビニルアルコール系樹脂からなる偏光フィルムに紫外線硬化型接着剤を介して光学フィルムを貼合し、偏光板を製造する。本発明の偏光板の製造方法は、以下の（Ａ）、（Ｂ）および（Ｃ）をこの順で含む。 [Polarizing plate manufacturing method and polarizing plate manufacturing apparatus]
In this invention, an optical film is bonded to the polarizing film which consists of a polyvinyl alcohol-type resin demonstrated above through an ultraviolet curable adhesive, and a polarizing plate is manufactured. The manufacturing method of the polarizing plate of this invention contains the following (A), (B) and (C) in this order.
　（Ａ）偏光フィルムおよび光学フィルムの少なくとも一方の貼合面に紫外線硬化型接着剤を塗工する塗工工程、
　（Ｂ）塗工された紫外線硬化型接着剤を介して偏光フィルムと光学フィルムとを重ね合わせて積層体を得る貼合工程、および
　（Ｃ）積層体に紫外線を照射して紫外線硬化型接着剤を硬化させる紫外線照射工程。 (A) a coating step of applying an ultraviolet curable adhesive to at least one bonding surface of the polarizing film and the optical film;
(B) A laminating step in which a polarizing film and an optical film are superposed through a coated ultraviolet curable adhesive to obtain a laminate, and (C) an ultraviolet curable adhesive by irradiating the laminate with ultraviolet rays. UV irradiation process to cure.
　本発明において上記塗工工程（Ａ）、貼合工程（Ｂ）および紫外線照射工程（Ｃ）は、４００ｎｍを超える波長域に発光波長を有し、２５０～４００ｎｍの波長域に発光波長を有しないＬＥＤ照明のもとで実施される。 In the present invention, the coating step (A), the bonding step (B), and the ultraviolet irradiation step (C) have an emission wavelength in a wavelength region exceeding 400 nm and do not have an emission wavelength in a wavelength region of 250 to 400 nm. Implemented under LED lighting.
　また本発明の偏光板製造装置は、上記本発明に係る偏光板の製造方法を好適に実施できる装置であり、以下の（Ａ１）、（Ｂ１）、（Ｃ１）および（Ｄ１）を含む。 Moreover, the polarizing plate production apparatus of the present invention is an apparatus that can suitably carry out the polarizing plate production method according to the present invention, and includes the following (A1), (B1), (C1), and (D1).
　（Ａ１）偏光フィルムおよび光学フィルムの少なくとも一方の貼合面に紫外線硬化型接着剤を塗工するための塗工手段、
　（Ｂ１）塗工された紫外線硬化型接着剤を介して偏光フィルムと光学フィルムとを重ね合わせて積層体を得るための貼合手段、
　（Ｃ１）積層体に紫外線を照射して紫外線硬化型接着剤を硬化させるための紫外線照射手段、および
　（Ｄ１）塗工手段（Ａ１）、貼合手段（Ｂ１）および紫外線照射手段（Ｃ１）を照明するための、４００ｎｍを超える波長域に発光波長を有し、２５０～４００ｎｍの波長域に発光波長を有しないＬＥＤ照明。 (A1) Coating means for applying an ultraviolet curable adhesive to at least one bonding surface of the polarizing film and the optical film,
(B1) A bonding means for obtaining a laminate by superimposing a polarizing film and an optical film via a coated ultraviolet curable adhesive,
(C1) An ultraviolet irradiation means for irradiating the laminate with ultraviolet rays to cure the ultraviolet curable adhesive, and (D1) a coating means (A1), a bonding means (B1) and an ultraviolet irradiation means (C1). LED illumination that has a light emission wavelength in a wavelength region exceeding 400 nm and does not have a light emission wavelength in a wavelength region of 250 to 400 nm for illumination.
　図１は、本発明の偏光板製造装置の一例を概略的に示す側面図である。図１に示す偏光板製造装置は、偏光フィルム１を連続的に搬送しながら、その一方の面に第一の光学フィルム２を貼合し、もう一方の面には第二の光学フィルム３を貼合して、偏光板４を製造し、巻取りロール３０に巻き取るように構成されている。この図に示すとおり、典型的には偏光フィルム１の両面にそれぞれ光学フィルムが貼合されるが、偏光フィルム１の一方の面にのみ光学フィルムを貼合する形態も、もちろん本発明に包含される。その場合の形態は、以下の説明からもう一方の光学フィルムに関する説明を除くことにより、当業者であれば容易に実施可能な程度に理解できるであろう。 FIG. 1 is a side view schematically showing an example of a polarizing plate production apparatus of the present invention. In the polarizing plate manufacturing apparatus shown in FIG. 1, the first optical film 2 is bonded to one surface while the polarizing film 1 is continuously conveyed, and the second optical film 3 is bonded to the other surface. The polarizing plate 4 is manufactured by bonding, and is wound around the winding roll 30. As shown in this figure, typically, an optical film is bonded to both surfaces of the polarizing film 1, but a mode in which the optical film is bonded only to one surface of the polarizing film 1 is also included in the present invention. The The form in that case will be understood by a person skilled in the art to the extent that it can be easily implemented by excluding the description of the other optical film from the following description.
　図１を参照して偏光板製造方法の概要について説明すると、まず塗工工程（Ａ）において、ロール体３１，３２から繰り出された第一の光学フィルム２および第二の光学フィルム３の一方の面に、塗工手段（Ａ１）である第一の塗工機１０および第二の塗工機１２のグラビアロール１１，１３から紫外線硬化型接着剤が塗工される。偏光フィルム１の一方の面や、第一の光学フィルム２および第二の光学フィルム３の紫外線硬化型接着剤が塗工される面と反対側の面には、搬送用のガイドロール２４が適宜設けられる。続く貼合工程（Ｂ）において、紫外線硬化型接着剤が塗工された第一の光学フィルム２および第二の光学フィルム３は、それぞれの接着剤塗工面が偏光フィルム１の両面に重ね合わされ、貼合手段（Ｂ１）である貼合用ニップロール２０，２１で挟んで厚み方向に加圧され、積層体が得られる。次いで、紫外線照射工程（Ｃ）において、紫外線照射手段（Ｃ１）である紫外線照射装置１４を用いて積層体に紫外線が照射され、紫外線硬化型接着剤が硬化される。得られた偏光板４は、巻取り前ニップロール２２，２３を経て、巻取りロール３０に巻き取られる。 The outline of the polarizing plate manufacturing method will be described with reference to FIG. 1. First, in the coating step (A), one of the first optical film 2 and the second optical film 3 fed out from the roll bodies 31 and 32. The surface is coated with an ultraviolet curable adhesive from the gravure rolls 11 and 13 of the first coating machine 10 and the second coating machine 12 which are the coating means (A1). On one surface of the polarizing film 1 and the surface of the first optical film 2 and the second optical film 3 opposite to the surface to which the ultraviolet curable adhesive is applied, a conveying guide roll 24 is appropriately provided. Provided. In the subsequent bonding step (B), the first optical film 2 and the second optical film 3 to which the ultraviolet curable adhesive has been applied are overlapped on both surfaces of the polarizing film 1, respectively. The laminate is obtained by being pressed between the nip rolls 20 and 21 for bonding, which is a bonding means (B1), in the thickness direction. Next, in the ultraviolet irradiation step (C), the laminate is irradiated with ultraviolet rays using the ultraviolet irradiation device 14 which is the ultraviolet irradiation means (C1), and the ultraviolet curable adhesive is cured. The obtained polarizing plate 4 is wound around the winding roll 30 via the nip rolls 22 and 23 before winding.
　上述のとおり、偏光フィルム１の一方の面にのみ光学フィルムを貼合する場合には、図１に示される第一の光学フィルム２および第二の光学フィルム３のうち、一方だけ（たとえば、第一の光学フィルム２だけ）が適用されるようにすればよい。図中の直線矢印はフィルムの流れ方向を意味し、曲線矢印はロールの回転方向を意味する。 As described above, when the optical film is bonded only to one surface of the polarizing film 1, only one of the first optical film 2 and the second optical film 3 shown in FIG. Only one optical film 2) may be applied. The straight arrows in the figure indicate the film flow direction, and the curved arrows indicate the roll rotation direction.
　以下、図１を参照しながら、本発明の偏光板の製造方法および偏光板製造装置についてさらに詳細に説明する。 Hereinafter, the polarizing plate manufacturing method and the polarizing plate manufacturing apparatus of the present invention will be described in more detail with reference to FIG.
　〔１〕塗工工程（Ａ）
　塗工工程（Ａ）では、第一、第二の光学フィルム２，３の偏光フィルム１への貼合面に紫外線硬化型接着剤が塗工される。ここで用いる塗工手段（Ａ１）としての塗工機は、塗工厚さを制御する手段を有するものであることが好ましく、このようなものとしては図１を参照して説明したグラビアロール１１，１３を用いる方式のものが代表的である。グラビアロール１１，１３は、凹溝を有するロールであって、その凹溝に予め紫外線硬化型接着剤が充填され、その状態で第一、第二の光学フィルム２，３上を回転することにより、第一、第二の光学フィルム２，３上に紫外線硬化型接着剤を転写する。 [1] Coating process (A)
In the coating step (A), an ultraviolet curable adhesive is applied to the bonding surfaces of the first and second optical films 2 and 3 to the polarizing film 1. The coating machine as the coating means (A1) used here preferably has a means for controlling the coating thickness, and as such a gravure roll 11 described with reference to FIG. , 13 is typical. The gravure rolls 11 and 13 are rolls having concave grooves, and the concave grooves are filled with an ultraviolet curable adhesive in advance, and the first and second optical films 2 and 3 are rotated in this state. The ultraviolet curable adhesive is transferred onto the first and second optical films 2 and 3.
　グラビアロール１１，１３を用いる塗工機には、たとえば、ダイレクトグラビアコーター、チャンバードクターコーター、オフセットグラビアコーター、グラビアロールを用いたキッスコーター、複数本のロールで構成されるリバースロールコーターなどがある。その他にも、円筒状のブレードを有し、塗工部に接着剤を供給してブレードで掻き落としつつ塗工するコンマコーター、スロットダイなどを応用して直接接着剤を供給するダイコーター、液溜めを作って、ナイフで余分な液を掻き落としつつ塗工するナイフコーターなど、種々の塗工機が利用できる。これらのうち、薄膜塗工であることやパスラインの自由度などを考慮すると、グラビアロールを用いる塗工機の中でも、ダイレクトグラビアコーター、チャンバードクターコーター、オフセットグラビアコーターなどが好ましく、またグラビアロール以外では、スロットダイを用いるダイコーターも好ましい。偏光板の広幅化に対応しやすいことや、液体で供給される紫外線硬化型接着剤の臭気を放出しにくいことから、チャンバードクターコーターがさらに好ましい。 Examples of the coating machine using the gravure rolls 11 and 13 include a direct gravure coater, a chamber doctor coater, an offset gravure coater, a kiss coater using a gravure roll, and a reverse roll coater composed of a plurality of rolls. In addition, a comma coater that has a cylindrical blade, supplies the coating part with an adhesive, and scrapes it off with the blade, and applies a slot die to directly apply the adhesive. Various coating machines, such as a knife coater that creates a reservoir and scrapes off excess liquid with a knife, can be used. Among these, direct gravure coater, chamber doctor coater, offset gravure coater, etc. are preferable among coating machines using gravure rolls, considering thin film coating and pass line freedom, etc. Then, a die coater using a slot die is also preferable. A chamber doctor coater is more preferable because it can easily cope with the widening of the polarizing plate and hardly releases the odor of the ultraviolet curable adhesive supplied as a liquid.
　ここで、チャンバードクターコーターとは、液状の塗料（接着剤）を吸液したチャンバードクターにグラビアロールを当接させて、チャンバードクター中の塗料（接着剤）をグラビアロールの凹溝に移し、これを第一、第二の光学フィルム２，３に転写する方式の塗工機である。コンパクトに設計されたものは、マイクロチャンバードクターコーターとも呼ばれる。 Here, the chamber doctor coater makes the gravure roll contact the chamber doctor that has absorbed the liquid paint (adhesive), and transfers the paint (adhesive) in the chamber doctor to the concave groove of the gravure roll. Is a coating machine that transfers the film to the first and second optical films 2 and 3. The compact design is also called a microchamber doctor coater.
　グラビアロール１１，１３を用いて紫外線硬化型接着剤を塗工する場合、接着剤層の厚さは、ライン速度に対するグラビアロールの速度比によって調整することができる。第一、第二の光学フィルム２，３のライン速度を１０～５０ｍ／分とし、グラビアロールは第一、第二の光学フィルム２，３の搬送方向に対して逆向きに回転させ、グラビアロールの回転周速度を１０～５００ｍ／分とすることで、接着剤層の厚さをたとえば０．５～５μｍとなるように調整できる。接着剤層の厚さは、グラビアロール表面の空隙率によっても影響を受けるので、事前に設定厚さに適した表面の空隙率を有するグラビアロールを選択しておくことが好ましい。なお、第一、第二の光学フィルム２，３の搬送方向に対してグラビアロールを逆向きに回転させる方式は、リバースグラビアとも呼ばれる。 When the UV curable adhesive is applied using the gravure rolls 11 and 13, the thickness of the adhesive layer can be adjusted by the speed ratio of the gravure roll to the line speed. The line speed of the first and second optical films 2 and 3 is set to 10 to 50 m / min, and the gravure roll is rotated in the opposite direction with respect to the conveying direction of the first and second optical films 2 and 3. By adjusting the rotational peripheral speed to 10 to 500 m / min, the thickness of the adhesive layer can be adjusted to 0.5 to 5 μm, for example. Since the thickness of the adhesive layer is also affected by the porosity of the gravure roll surface, it is preferable to select a gravure roll having a surface porosity suitable for the set thickness in advance. In addition, the system which rotates a gravure roll reversely with respect to the conveyance direction of the 1st, 2nd optical films 2 and 3 is also called a reverse gravure.
　製造される偏光板４の品質の観点から、第一、第二の光学フィルム２，３の偏光フィルム１との貼合面に塗工された接着剤層の厚さを計測し、接着剤層の厚さが一定となるように制御することが好ましい。計測方法としては、光干渉法、レーザー光干渉法、超音波法、β線やＸ線等の放射線を利用した方法など任意の方法を採用することができる。なかでも、光干渉法により第一、第二の光学フィルム２、３上の接着剤層の厚さのみを計測する方法、または、レーザー光干渉法、放射線をを利用する方法により、塗工前の第一、第二の光学フィルム２、３の厚さを計測し、塗工後の接着剤と光学フィルムとの合計厚さを計測し、これらの計測値の差の絶対値から接着剤層の厚さを求める方法が、計測精度の高さおよび計測の安定性の観点から好ましい。 From the viewpoint of the quality of the polarizing plate 4 to be produced, the thickness of the adhesive layer applied to the bonding surface of the first and second optical films 2 and 3 with the polarizing film 1 is measured, and the adhesive layer It is preferable to control the thickness of the film so as to be constant. As a measurement method, an arbitrary method such as a light interference method, a laser light interference method, an ultrasonic method, a method using radiation such as β rays or X rays can be adopted. In particular, before coating, a method of measuring only the thickness of the adhesive layer on the first and second optical films 2 and 3 by a light interference method, or a method using a laser light interference method and radiation. The thickness of the first and second optical films 2 and 3 is measured, the total thickness of the adhesive and the optical film after coating is measured, and the adhesive layer is determined from the absolute value of the difference between these measured values. The method of obtaining the thickness of the film is preferable from the viewpoint of high measurement accuracy and measurement stability.
　偏光フィルム１は、図示しない偏光フィルム製造工程において、ポリビニルアルコール系樹脂フィルムに、一軸延伸処理、二色性色素による染色処理、および染色後のホウ酸架橋処理を経て製造された状態でそのまま塗工工程（Ａ）に供されることが多いが、もちろん、偏光フィルム製造工程において製造された偏光フィルムを一旦ロールに巻き取った後、改めて繰出し機によって繰り出すようにしても構わない。一方、第一の光学フィルム２および第二の光学フィルム３は、それぞれロール体３１，３２から繰出し機により繰り出される。それぞれのフィルムは、同じライン速度で、たとえば１０～５０ｍ／分程度のライン速度で、流れ方向が同じになるように搬送される。第一の光学フィルム２および第二の光学フィルム３は、流れ方向に５０～１０００Ｎ／ｍ程度の張力をかけながら繰り出される。 The polarizing film 1 is directly applied to a polyvinyl alcohol resin film in a state of being manufactured through a uniaxial stretching process, a dyeing process with a dichroic dye, and a boric acid crosslinking process after dyeing in a polarizing film manufacturing process (not shown). Often, it is provided to the step (A), but of course, the polarizing film manufactured in the polarizing film manufacturing step may be once wound around a roll and then fed out again by a feeding machine. On the other hand, the first optical film 2 and the second optical film 3 are fed out from the roll bodies 31 and 32 by a feeding machine, respectively. Each film is conveyed so as to have the same flow direction at the same line speed, for example, a line speed of about 10 to 50 m / min. The first optical film 2 and the second optical film 3 are fed out while applying a tension of about 50 to 1000 N / m in the flow direction.
　〔２〕貼合工程（Ｂ）
　塗工工程（Ａ）を経た後、第一、第二の光学フィルム２，３のそれぞれの接着剤塗工面に、偏光フィルム１を重ねて加圧し、積層体を得る貼合工程（Ｂ）が行なわれる。この工程における貼合手段（Ｂ１）には公知の手段を用いることができるが、連続搬送しながらの加圧、貼合が可能であるという観点からは、図１に示すように、一対の貼合用ニップロール２０，２１により挟む方式が好ましい。この場合、偏光フィルム１に第一、第二の光学フィルム２，３を重ね合わせるタイミングと、一対のニップロール２０，２１によって加圧するタイミングは、同じであることが望ましく、たとえ違っても、両者のタイミングの差は短いほうが好ましい。一対のニップロール２０，２１の組合せは、金属ロール／金属ロール、金属ロール／ゴムロール、ゴムロール／ゴムロールなど、いずれであってもよい。加圧時の圧力は、一対のニップロール２０，２１により挟む場合の線圧で１５０～５００Ｎ／ｃｍ程度とするのが好ましい。 [2] Pasting process (B)
After passing through the coating step (A), there is a bonding step (B) in which the polarizing film 1 is stacked and pressed on each adhesive coating surface of the first and second optical films 2 and 3 to obtain a laminate. Done. Although a well-known means can be used for the bonding means (B1) in this process, as shown in FIG. 1, a pair of bonding is possible from a viewpoint that pressurization and bonding are possible while continuously conveying. A method of sandwiching between the nip rolls 20 and 21 is preferable. In this case, it is desirable that the timing of superimposing the first and second optical films 2 and 3 on the polarizing film 1 and the timing of applying pressure by the pair of nip rolls 20 and 21 are the same. A shorter timing difference is preferable. The combination of the pair of nip rolls 20 and 21 may be any of metal roll / metal roll, metal roll / rubber roll, rubber roll / rubber roll, and the like. The pressure during pressurization is preferably about 150 to 500 N / cm as the linear pressure when sandwiched between the pair of nip rolls 20 and 21.
　〔３〕紫外線照射工程（Ｃ）
　以上のようにして、偏光フィルム１に第一、第二の光学フィルム２，３を貼合して積層体を得た後、紫外線の照射により紫外線硬化型接着剤からなる接着剤層を硬化させる紫外線照射工程（Ｃ）を経て偏光板４が製造される。この紫外線照射工程（Ｃ）は、紫外線照射手段（Ｃ１）としての紫外線照射装置１４から積層体に紫外線を照射することにより行なわれる。この工程では、紫外線硬化型接着剤を硬化させるために必要なエネルギーを有する紫外線が、第一の光学フィルム２（または第二の光学フィルム３）越しに照射される。 [3] Ultraviolet irradiation process (C)
As described above, after the first and second optical films 2 and 3 are bonded to the polarizing film 1 to obtain a laminate, an adhesive layer made of an ultraviolet curable adhesive is cured by irradiation with ultraviolet rays. The polarizing plate 4 is manufactured through the ultraviolet irradiation step (C). This ultraviolet irradiation step (C) is performed by irradiating the laminate with ultraviolet rays from the ultraviolet irradiation device 14 as the ultraviolet irradiation means (C1). In this step, ultraviolet light having energy necessary for curing the ultraviolet curable adhesive is irradiated through the first optical film 2 (or the second optical film 3).
　図１に示す例では、積層体への紫外線の照射が、紫外線照射装置１４の前後にある貼合用ニップロール２０，２１と巻取り前ニップロール２２，２３との間で積層体に張力をかけた状態で行なわれるようになっている。ただしこれに限らず、たとえば先の特許文献２（特開２００９－１３４１９０号公報）に開示されるような、搬送方向に沿って円弧状に形成された凸曲面、典型的にはロールの外周面に支持された状態で紫外線を照射するのも好ましい。特に、紫外線の照射により熱が発生し、製品に悪影響を及ぼす可能性があるときは、後者のように積層体がロールの外周面に支持された状態でそこに紫外線を照射するのが好ましく、この場合、積層体を支持するロールは、１０～６０℃程度の範囲で温度調節できるようになっていることが好ましい。 In the example shown in FIG. 1, irradiation of the laminate with ultraviolet rays applied tension to the laminate between the nip rolls 20 and 21 for bonding before and after the ultraviolet irradiation device 14 and the nip rolls 22 and 23 before winding. It is to be performed in the state. However, the present invention is not limited to this, for example, a convex curved surface formed in an arc shape along the conveying direction as disclosed in the above-mentioned Patent Document 2 (Japanese Patent Laid-Open No. 2009-134190), typically the outer peripheral surface of the roll. It is also preferable to irradiate with ultraviolet rays while being supported by the substrate. In particular, when heat is generated by irradiation of ultraviolet rays and there is a possibility of adversely affecting the product, it is preferable to irradiate ultraviolet rays there in a state where the laminate is supported on the outer peripheral surface of the roll as in the latter case, In this case, it is preferable that the roll supporting the laminated body can be adjusted in temperature in the range of about 10 to 60 ° C.
　紫外線照射装置１４は、照射部位に１個だけ設けてもよいが、積層体の流れ方向に沿って２個以上設け、複数光源から照射することも、積算光量を効果的に高めるうえで有効である。いずれの場合においても紫外線照射装置１４は、その直下を通過する積層体にのみ紫外線が照射されるようにすることが好ましい。 Although only one ultraviolet irradiation device 14 may be provided at the irradiation site, two or more ultraviolet irradiation devices along the flow direction of the laminated body and irradiation from a plurality of light sources are effective in effectively increasing the integrated light quantity. is there. In any case, it is preferable that the ultraviolet irradiation device 14 is configured to irradiate ultraviolet rays only to the laminate that passes immediately below.
　紫外線照射装置１４の紫外線光源は特に限定されないが、波長４００ｎｍ以下に発光分布を有する、たとえば、低圧水銀灯、中圧水銀灯、高圧水銀灯、超高圧水銀灯、ケミカルランプ、ブラックライトランプ、マイクロウェーブ励起水銀灯、メタルハライドランプなどを用いることができる。エポキシ化合物を紫外線硬化性成分とする接着剤を用いる場合、一般的な重合開始剤が示す吸収波長を考慮すると、４００ｎｍ以下の光を多く有する高圧水銀灯またはメタルハライドランプが、紫外線光源として好ましく用いられる。 Although the ultraviolet light source of the ultraviolet irradiation device 14 is not particularly limited, it has a light emission distribution at a wavelength of 400 nm or less. A metal halide lamp or the like can be used. When an adhesive having an epoxy compound as an ultraviolet curable component is used, a high pressure mercury lamp or a metal halide lamp having a large amount of light of 400 nm or less is preferably used as the ultraviolet light source in consideration of an absorption wavelength exhibited by a general polymerization initiator.
　積層体の長手方向（搬送方向）に１００～１０００Ｎ／ｍの張力をかけながら、重合開始剤の活性化に有効な波長領域の照射量が、積算光量（積層体に照射されるトータルエネルギー）で１００～１５００ｍＪ／ｃｍ2となるように紫外線を照射することが好ましい。積算光量が少なすぎると、紫外線硬化型接着剤の硬化反応が不足し、十分な接着強度が発現されにくくなり、一方でその積算光量が大きすぎると、光源から輻射される熱および接着剤が重合するときに発生する熱により、紫外線硬化型接着剤の黄変や偏光フィルムの劣化を引き起こす可能性がある。 While applying a tension of 100 to 1000 N / m in the longitudinal direction (conveying direction) of the laminate, the irradiation amount in the wavelength region effective for activating the polymerization initiator is the integrated light amount (total energy irradiated to the laminate). It is preferable to irradiate with ultraviolet rays so as to be 100 to 1500 mJ / cm 2 . If the accumulated light amount is too small, the curing reaction of the UV curable adhesive will be insufficient, and sufficient adhesive strength will not be expressed. On the other hand, if the accumulated light amount is too large, the heat and adhesive emitted from the light source will be polymerized. The heat generated during the process may cause yellowing of the ultraviolet curable adhesive and deterioration of the polarizing film.
　また、１回の紫外線照射で必要な積算光量を達成しようとすると、発熱によりフィルムが１５０℃を超える高温になることもあり、その場合には偏光フィルムの劣化などを引き起こす可能性がある。このような事態を避けるうえでも、先に述べたように紫外線照射装置をフィルムの搬送方向に沿って複数設け、複数回に分けて照射することが有効である。目安として、１個所の紫外線照射装置からの照射量は、積算光量で６００ｍＪ／ｃｍ2以下とし、最終的に上記した１００～１５００ｍＪ／ｃｍ2の積算光量が得られるようにすることが好ましい場合がある。 Further, if it is attempted to achieve the necessary integrated light quantity by one ultraviolet irradiation, the film may be heated to a high temperature exceeding 150 ° C. due to heat generation. In this case, the polarizing film may be deteriorated. In order to avoid such a situation, as described above, it is effective to provide a plurality of ultraviolet irradiation devices along the film conveyance direction and to irradiate a plurality of times. As a guideline, it may be preferable to set the irradiation amount from one ultraviolet irradiation device to 600 mJ / cm 2 or less in terms of the integrated light amount so that the above-mentioned integrated light amount of 100 to 1500 mJ / cm 2 is finally obtained. is there.
　図１に示されるように、紫外線照射装置１４からの照射量を、照度計１５を用いて計測し、管理することが好ましい。照度計１５としては、照射される紫外線を波長ごとに分光して、各波長毎の照度を計測できるものが好ましい。硬化反応に必要な波長域の照度を積算し、積算光量を求め、これに基づいて紫外線照射装置１４からの照射量を管理することにより、十分な接着強度を有する偏光板を連続生産することができる。 As shown in FIG. 1, it is preferable to measure and manage the irradiation amount from the ultraviolet irradiation device 14 using an illuminance meter 15. The illuminance meter 15 is preferably one that can measure the illuminance for each wavelength by dispersing the irradiated ultraviolet rays for each wavelength. It is possible to continuously produce a polarizing plate having sufficient adhesive strength by integrating the illuminance in the wavelength region necessary for the curing reaction, obtaining the integrated light amount, and managing the irradiation amount from the ultraviolet irradiation device 14 based on this. it can.
　紫外線照射工程（Ｃ）における積層体のライン速度は特に限定されないが、一般には、塗工工程（Ａ）や貼合工程（Ｂ）におけるライン速度がほぼそのまま維持される。 The line speed of the laminate in the ultraviolet irradiation step (C) is not particularly limited, but generally the line speed in the coating step (A) and the bonding step (B) is maintained almost as it is.
　〔４〕ＬＥＤ照明
　本発明において、上記塗工工程（Ａ）、貼合工程（Ｂ）および紫外線照射工程（Ｃ）は、４００ｎｍを超える波長域に発光波長を有し、２５０～４００ｎｍの波長域に発光波長を有しないＬＥＤ（発光ダイオード）照明（Ｄ１）のもとで実施される。ＬＥＤ照明（Ｄ１）は、少なくとも上記塗工手段（Ａ１）、貼合手段（Ｂ１）および紫外線照射手段（Ｃ１）を照明するものである。 [4] LED illumination In the present invention, the coating step (A), the bonding step (B) and the ultraviolet irradiation step (C) have an emission wavelength in a wavelength region exceeding 400 nm, and a wavelength region of 250 to 400 nm. This is performed under LED (light emitting diode) illumination (D1) having no emission wavelength. The LED illumination (D1) illuminates at least the coating means (A1), the bonding means (B1), and the ultraviolet irradiation means (C1).
　４００ｎｍを超える波長域に発光波長を有し、２５０～４００ｎｍの波長域に発光波長を有しないＬＥＤ照明（Ｄ１）とは、分光機能を有するパワーモニター（たとえば、大塚電子（株）製の分光放射照度測定システム「ＭＣＰＤ－９８００」、「ＭＣＰＤ-７７００」または「ＭＣＰＤ－３７００」など）を用いて測定される各波長毎の照度スペクトルにおいて、４００ｎｍを超える波長域に照度のピークが見られ、２５０～４００ｎｍの波長域に照度のピークが見られないＬＥＤ照明である。 An LED illumination (D1) having a light emission wavelength in a wavelength region exceeding 400 nm and not having a light emission wavelength in a wavelength region of 250 to 400 nm is a power monitor having a spectral function (for example, spectral radiation manufactured by Otsuka Electronics Co., Ltd.) In an illuminance spectrum for each wavelength measured using an illuminance measurement system “MCPD-9800”, “MCPD-7700”, “MCPD-3700”, etc., an illuminance peak is observed in a wavelength region exceeding 400 nm, and 250 It is LED illumination in which the peak of illuminance is not seen in the wavelength range of ˜400 nm.
　ＬＥＤ照明は、ＬＥＤチップと呼ばれるＰ型半導体とＮ型半導体が接合されたＰＮ接合で構成されるものに電圧をかけることで発光するが、そのＬＥＤチップを構成する化合物の種類により発光色を青色（４５０ｎｍ前後）、緑色（５２０ｎｍ前後）または赤色（６６０ｎｍ前後）とすることができる。白色のＬＥＤ照明は、青色の発光と黄色の蛍光体とを組合せ、青色の発光より蛍光体を励起させ白色発光としたもの；青色の発光と赤・緑色蛍光体との組合せで蛍光体を励起させることで白色発光としたもの；青色、緑色および赤色の発光を混色して白色発光としたものがあり、これらのＬＥＤ照明は、４００ｎｍを超える波長域に発光波長を有し、２５０～４００ｎｍの波長域に発光波長を有しないのでＬＥＤ照明（Ｄ１）として用いることができる。ＬＥＤチップと蛍光体との組合せにおいて、ＬＥＤチップの発光波長が、紫外線領域である３６０ｎｍ付近のもの、あるいは、４０５ｎｍ付近であるＬＥＤ照明も開発されているが、これらは、４００ｎｍ以下の発光波長を有するため、ＬＥＤ照明（Ｄ１）には適さない。 LED lighting emits light when a voltage is applied to a PN junction composed of a P-type semiconductor and an N-type semiconductor called an LED chip, but the emission color is blue depending on the type of compound constituting the LED chip. (Around 450 nm), green (around 520 nm) or red (around 660 nm). White LED lighting is a combination of blue light emission and yellow phosphor, which excites the phosphor from blue light emission to produce white light emission; a combination of blue light emission and red / green phosphor excites the phosphor. White light emission by mixing blue, green and red light emission, and these LED illuminations have a light emission wavelength in the wavelength region exceeding 400 nm and have a wavelength of 250 to 400 nm. Since it does not have an emission wavelength in the wavelength range, it can be used as LED lighting (D1). In the combination of the LED chip and the phosphor, LED lighting whose LED chip emission wavelength is near 360 nm in the ultraviolet region or 405 nm is also being developed, but these have an emission wavelength of 400 nm or less. Therefore, it is not suitable for LED lighting (D1).
　４００ｎｍを超える波長域に発光波長を有し、２５０～４００ｎｍの波長域に発光波長を有しないＬＥＤ照明（Ｄ１）を使用することで、塗工工程（Ａ）においては、使用（塗工）前の紫外線硬化型接着剤および光学フィルム（または偏光フィルム）に塗工された紫外線硬化型接着剤の意図しない硬化反応の進行を抑制でき、また、貼合工程（Ｂ）および紫外線照射工程（Ｃ）においても、積層体の端部からはみ出た紫外線硬化型接着剤の意図しない（紫外線照射装置によるものではない）硬化反応の進行を抑制できる。これにより、塗工前に硬化反応が進行することによる紫外線硬化型接着剤の接着性能の低下を抑制することができる。 By using LED lighting (D1) that has a light emission wavelength in the wavelength range exceeding 400 nm and does not have a light emission wavelength in the wavelength range of 250 to 400 nm, in the coating step (A), before use (coating) UV curing adhesive and optical film (or polarizing film) coated with UV curing adhesive can prevent the unintended curing reaction from progressing, and bonding process (B) and UV irradiation process (C) In this case, it is possible to suppress the unintended (not based on the ultraviolet irradiation device) curing reaction of the ultraviolet curable adhesive protruding from the end of the laminate. Thereby, the fall of the adhesive performance of the ultraviolet curable adhesive by a hardening reaction advancing before coating can be suppressed.
　また、積層体の端部からはみ出た紫外線硬化型接着剤がガイドロール等に付着したり、光学フィルム等のフィルムが製造工程中に破断して、塗工した紫外線硬化型接着剤が飛散したりするなどの製造トラブルが発生した場合においても、ガイドロール等に付着した、または飛散した接着剤の硬化を抑制することができるので、これらの接着剤を溶剤などで容易に除去することができる。これにより上記のような製造トラブルが発生した場合においても、短時間で製造工程を復旧させることができ、製造工程の稼働率を著しく低下せることなく、偏光板を製造することができる。得られる偏光板は、積層体の端部からはみ出て、硬化した紫外線硬化型接着剤に由来する打痕等の欠陥を生じる頻度が少ない。 In addition, the UV curable adhesive that protrudes from the edge of the laminate adheres to the guide roll or the like, or the film such as an optical film breaks during the manufacturing process, and the applied UV curable adhesive scatters. Even when a manufacturing trouble such as this occurs, the adhesive attached to the guide roll or the like can be prevented from being cured, so that these adhesives can be easily removed with a solvent or the like. Thereby, even when the above manufacturing trouble occurs, the manufacturing process can be restored in a short time, and the polarizing plate can be manufactured without significantly reducing the operating rate of the manufacturing process. The obtained polarizing plate protrudes from the edge part of a laminated body, and there is little frequency which produces defects, such as a dent resulting from the hardened | cured ultraviolet curing adhesive.
　また、紫外線照射工程（Ｃ）で照射される紫外線のみで紫外線硬化型接着剤の硬化反応が進行するので、設定どおりの積算光量で紫外線照射を行なうために、紫外線照射装置からの紫外線の積算光量の管理のみを行なえばよいという利点もある。 Further, since the curing reaction of the ultraviolet curable adhesive proceeds only with the ultraviolet rays irradiated in the ultraviolet irradiation step (C), the cumulative amount of ultraviolet rays from the ultraviolet irradiation device is used to irradiate the ultraviolet rays with the set cumulative amount of light. There is also an advantage that it is only necessary to manage.
　さらに、ＬＥＤ照明（Ｄ１）の使用によれば、偏光板製造工程中におけるフィルム上の接着剤の塗工状態を目視で明瞭に確認することができるので、接着剤の塗工状態の不具合を目視検知するうえでも有利である。たとえば一般的な蛍光灯に紫外線カットフィルターを設置した紫外線カット蛍光灯によれば、４００ｎｍ以下の照度ピークをカットすることができるが、この場合、一般的に発光色が黄色くなるため、偏光板製造工程中におけるフィルム上の接着剤の塗工状態を目視で確認することが非常に困難となる。 Furthermore, according to the use of the LED illumination (D1), the coating state of the adhesive on the film during the polarizing plate manufacturing process can be clearly confirmed by visual observation. It is also advantageous for detection. For example, according to an ultraviolet cut fluorescent lamp in which an ultraviolet cut filter is installed in a general fluorescent lamp, an illuminance peak of 400 nm or less can be cut. It is very difficult to visually confirm the coating state of the adhesive on the film during the process.
　ＬＥＤ照明（Ｄ１）の設置位置は、塗工手段（Ａ１）、貼合手段（Ｂ１）および紫外線照射手段（Ｃ１）のすべてを照明することができる限り特に制限されず、偏光板製造装置が設置される偏光板製造施設（工場）内の上方（たとえば天井）に設置されてもよく、あるいは、偏光板製造装置自体がＬＥＤ照明（Ｄ１）を備えていてもよく、またはその双方であってもよい。本発明の偏光板製造装置は、それ自体ＬＥＤ照明（Ｄ１）を備えるものである。 The installation position of the LED illumination (D1) is not particularly limited as long as it can illuminate all of the coating means (A1), the bonding means (B1), and the ultraviolet irradiation means (C1), and the polarizing plate manufacturing apparatus is installed. The polarizing plate manufacturing facility (factory) may be installed above (for example, the ceiling), or the polarizing plate manufacturing apparatus itself may be equipped with the LED illumination (D1), or both. Good. The polarizing plate manufacturing apparatus of the present invention itself includes LED illumination (D1).
　たとえば偏光板製造装置自体がＬＥＤ照明（Ｄ１）を備える場合、偏光板製造装置は、塗工手段（Ａ１）、貼合手段（Ｂ１）および紫外線照射手段（Ｃ１）を収容する（塗工工程（Ａ）、貼合工程（Ｂ）および紫外線照射工程（Ｃ）が実施される製造工程部分の周囲を覆う）１以上のチャンバを有することができ、このチャンバ内に１以上のＬＥＤ照明（Ｄ１）を設置することができる。図１に示される例においては、２つの塗工手段（Ａ１）、１つの貼合手段（Ｂ１）、１つの紫外線照射手段（Ｃ１）をそれぞれ収容する合計４つのチャンバを備えており、これら４つのチャンバのそれぞれに１つのＬＥＤ照明（Ｄ１）（ＬＥＤ照明４０，４１，４２，４３）が設けられている。作業スペースの有効利用の観点から、ＬＥＤ照明（Ｄ１）は、チャンバ内の上方（たとえば天井）や横方（チャンバの側面）に設置することが好ましい。 For example, when the polarizing plate manufacturing apparatus itself includes LED lighting (D1), the polarizing plate manufacturing apparatus accommodates the coating means (A1), the bonding means (B1), and the ultraviolet irradiation means (C1) (coating process ( A), one or more chambers (covering the periphery of the manufacturing process part in which the bonding step (B) and the ultraviolet irradiation step (C) are performed) can be provided, and one or more LED illuminations (D1) in this chamber Can be installed. In the example shown in FIG. 1, a total of four chambers each accommodating two coating means (A1), one bonding means (B1), and one ultraviolet irradiation means (C1) are provided. One LED illumination (D1) ( LED illumination 40, 41, 42, 43) is provided in each of the two chambers. From the viewpoint of effective use of the work space, it is preferable that the LED illumination (D1) be installed above (for example, the ceiling) or laterally (side of the chamber) in the chamber.
　なお、偏光板製造装置に塗工手段（Ａ１）、貼合手段（Ｂ１）および紫外線照射手段（Ｃ１）を収容する（塗工工程（Ａ）、貼合工程（Ｂ）および紫外線照射工程（Ｃ）が実施される製造工程部分の周囲を覆う）チャンバが設けられ、かつそのチャンバ内にＬＥＤ照明（Ｄ１）が設置される場合には、偏光板製造施設（工場）が有する照明は、必ずしもＬＥＤ照明（Ｄ１）である必要はない。 In addition, a coating means (A1), a bonding means (B1), and an ultraviolet irradiation means (C1) are accommodated in the polarizing plate manufacturing apparatus (the coating process (A), the bonding process (B), and the ultraviolet irradiation process (C In the case where a chamber is provided that covers the periphery of the manufacturing process portion where the manufacturing process is performed) and the LED illumination (D1) is installed in the chamber, the illumination of the polarizing plate manufacturing facility (factory) is not necessarily LED. There is no need for illumination (D1).
　製造工程中に光学フィルム等のフィルムが破断するような製造トラブルが発生した場合においては、紫外線照射工程（Ｃ）の後工程にも、未硬化の紫外線硬化型接着剤が持ち込まれることがある。したがって、このような場合においても接着剤を容易に除去できるよう、紫外線照射工程（Ｃ）から巻取りロール３０による偏光板４の巻き取りまでの工程も、ＬＥＤ照明（Ｄ１）のもとで実施することが好ましい。 In the case where a production trouble occurs in which a film such as an optical film breaks during the production process, an uncured ultraviolet curable adhesive may be brought into the subsequent process of the ultraviolet irradiation process (C). Therefore, the steps from the ultraviolet irradiation step (C) to the winding of the polarizing plate 4 by the winding roll 30 are also performed under the LED illumination (D1) so that the adhesive can be easily removed even in such a case. It is preferable to do.
　以下に実施例および比較例を示して、本発明をさらに具体的に説明するが、本発明はこれらの例によって限定されるものではない。 Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples.
　［実施例１］
　（０）実験に用いた材料
　この例では、偏光板製造を実施する偏光板製造装置として、図１に示される構成のものを用い、偏光フィルム１と第一の光学フィルム２との接着に用いる接着剤、および偏光フィルム１と第二の光学フィルム３との接着に用いる接着剤として、いずれもエポキシ化合物と光重合開始剤を含み、実質的に溶剤を含まないエポキシ系紫外線硬化型接着剤を用いた。また、第一の光学フィルム２として、厚さが６０μｍで幅が１３３０ｍｍ幅の二軸配向性シクロオレフィン系樹脂フィルム〔日本ゼオン（株）から入手〕を、第二の光学フィルム３として、厚さが８０μｍで幅が１３３０ｍｍのトリアセチルセルロースフィルム「ＫＣ８ＵＸ２ＭＷ」〔コニカミノルタオプト（株）から入手〕を用いた。 [Example 1]
(0) Material used in the experiment In this example, the polarizing plate manufacturing apparatus for manufacturing the polarizing plate has the configuration shown in FIG. 1 and is used for bonding the polarizing film 1 and the first optical film 2. As an adhesive and an adhesive used for adhesion between the polarizing film 1 and the second optical film 3, an epoxy-based ultraviolet curable adhesive that contains an epoxy compound and a photopolymerization initiator and substantially does not contain a solvent. Using. In addition, as the first optical film 2, a biaxially oriented cycloolefin resin film [obtained from Nippon Zeon Co., Ltd.] having a thickness of 60 μm and a width of 1330 mm is used as the second optical film 3. Used was a triacetyl cellulose film “KC8UX2MW” (obtained from Konica Minolta Opto Co., Ltd.) having a width of 80 μm and a width of 1330 mm.
　（１）偏光板の製造
　ポリビニルアルコールにヨウ素が吸着配向している厚さ２５μｍの偏光フィルム１、第一の光学フィルム２および第二の光学フィルム３を、それぞれ１５ｍ／分のライン速度で流れ方向が同じになるように供給した。第一の光学フィルム２の偏光フィルム１への貼合面には、グラビアロール１１を備える第一の塗工機１０〔富士機械（株）製の「マイクロチャンバードクター」〕を用いて、接着剤層の厚さが３．０μｍとなるようにグラビアロール１１の回転数を制御しながら、上記の紫外線硬化型接着剤を塗工した。同様に、第二の光学フィルム３の偏光フィルム１への貼合面には、グラビアロール１２を備える第二の塗工機１２〔富士機械（株）製の「マイクロチャンバードクター」〕を用いて、接着剤層の厚さが３．５μｍとなるように上記の紫外線硬化型接着剤を塗工した〔塗工工程（Ａ）〕。 (1) Production of polarizing plate Flow direction of polarizing film 1 having a thickness of 25 μm in which iodine is adsorbed and oriented on polyvinyl alcohol, first optical film 2 and second optical film 3 at a line speed of 15 m / min. Were supplied to be the same. On the bonding surface of the first optical film 2 to the polarizing film 1, an adhesive is used by using a first coating machine 10 (“Microchamber Doctor” manufactured by Fuji Machine Co., Ltd.) equipped with a gravure roll 11. While controlling the rotation speed of the gravure roll 11 so that the thickness of the layer becomes 3.0 μm, the ultraviolet curable adhesive was applied. Similarly, on the bonding surface of the second optical film 3 to the polarizing film 1, a second coating machine 12 (“Microchamber Doctor” manufactured by Fuji Machine Co., Ltd.) provided with a gravure roll 12 is used. The UV curable adhesive was applied so that the thickness of the adhesive layer was 3.5 μm [Coating process (A)].
　次いで、紫外線硬化型接着剤が塗工された第一の光学フィルム２および第二の光学フィルム３のそれぞれの接着剤塗工面を偏光フィルム１に重ね合わせ、貼合用ニップロール２０，２１により２４０Ｎ／ｃｍの線圧で挟んだ〔貼合工程（Ｂ）〕。次に、ニップロール２０，２１を通過した後の積層体に対し、紫外線照射装置１４より紫外線を照射し、紫外線硬化型を硬化させ〔紫外線照射工程（Ｃ）〕、得られた偏光板４を巻取りロール３０に巻き取った。紫外線照射装置１４としては、（株）ＧＳユアサ製の紫外線ランプ「ＥＨＡＮ１７００ＮＡＬ高圧水銀ランプ」２灯を使用した。紫外線の積算光量は、２灯合わせて３３０ｍＪ／ｃｍ2であった。 Next, the respective adhesive-coated surfaces of the first optical film 2 and the second optical film 3 coated with the ultraviolet curable adhesive are superposed on the polarizing film 1, and 240 N / O is applied by the nip rolls 20 and 21 for bonding. Clamped with a linear pressure of cm [bonding step (B)]. Next, the laminated body after passing through the nip rolls 20 and 21 is irradiated with ultraviolet rays from the ultraviolet irradiation device 14 to cure the ultraviolet curing type [ultraviolet irradiation step (C)], and the obtained polarizing plate 4 is wound. It was wound up on a take-up roll 30. As the ultraviolet irradiation device 14, two ultraviolet lamps “EHAN1700NAL high-pressure mercury lamp” manufactured by GS Yuasa Co., Ltd. were used. The cumulative amount of ultraviolet light was 330 mJ / cm 2 for the two lamps.
　塗工工程（Ａ）、貼合工程（Ｂ）および紫外線照射工程（Ｃ）が実施される製造工程部分の周囲を覆う合計４つチャンバの天井には、それぞれ４００ｎｍを超える波長域に発光波長を有し、２５０～４００ｎｍの波長域に発光波長を有しないＬＥＤ照明４０，４１，４２，４３を設置し、塗工工程（Ａ）、貼合工程（Ｂ）および紫外線照射工程（Ｃ）はこれらのＬＥＤ照明のもとで実施した。用いたＬＥＤ照明４０，４１，４２，４３の照度スペクトルを図２に示す。 The ceiling of the four chambers covering the periphery of the manufacturing process part where the coating process (A), the bonding process (B), and the ultraviolet irradiation process (C) are performed has emission wavelengths in a wavelength region exceeding 400 nm respectively. LED lighting 40, 41, 42, 43 having no emission wavelength in the wavelength region of 250 to 400 nm is installed, and the coating process (A), the bonding process (B), and the ultraviolet irradiation process (C) are these It was carried out under LED lighting. The illuminance spectrum of the LED lighting 40, 41, 42, 43 used is shown in FIG.
　ＬＥＤ照明の照度スペクトルは、大塚電子（株）製の分光放射照度測定システム「ＭＣＰＤ－３７００」（検出器２４８０Ｃ）を用い、ＬＥＤ照明から３００ｍｍの距離にて照明光を取り込み、２２０～８００ｎｍ間の波長域において測定した。測定条件は、光取り込み時間４００ｍ秒として測定値を８回積算した。１ｎｍ毎の各波長における照度（Ｗ／分／ｎｍ）を得た。本実施例で用いたＬＥＤ照明は、２５０～４００ｎｍの波長域に発光波長を有しないことが確認された。 The illuminance spectrum of LED illumination is obtained by using a spectral irradiance measurement system “MCPD-3700” (detector 2480C) manufactured by Otsuka Electronics Co., Ltd. Measured in the wavelength range. Measurement conditions were such that the measured values were accumulated eight times with a light capture time of 400 milliseconds. Illuminance (W / min / nm) at each wavelength for every 1 nm was obtained. It was confirmed that the LED illumination used in this example does not have an emission wavelength in the wavelength range of 250 to 400 nm.
　［比較例１］
　実施例１におけるＬＥＤ照明の代わりに、２５０～４００ｎｍの波長域に発光波長を有しない紫外線カット蛍光灯を使用したこと以外は実施例１と同様して偏光板を作製した。用いた紫外線カット蛍光灯の照度スペクトルを図３に示す。 [Comparative Example 1]
A polarizing plate was produced in the same manner as in Example 1 except that instead of the LED illumination in Example 1, an ultraviolet cut fluorescent lamp having no emission wavelength in the wavelength range of 250 to 400 nm was used. The illuminance spectrum of the ultraviolet cut fluorescent lamp used is shown in FIG.
　［比較例２］
　実施例１におけるＬＥＤ照明の代わりに、３６５ｎｍ付近に発光波長を有する蛍光灯を使用したこと以外は実施例１と同様して偏光板を作製した。用いた蛍光灯の照度スペクトルを図４に示す。 [Comparative Example 2]
A polarizing plate was produced in the same manner as in Example 1 except that a fluorescent lamp having an emission wavelength in the vicinity of 365 nm was used instead of the LED illumination in Example 1. The illuminance spectrum of the fluorescent lamp used is shown in FIG.
　（評価試験）
　〔ａ〕接着剤の塗工状態の目視観察検査
　塗工工程（Ａ）のチャンバ内を通過する紫外線硬化型接着剤が塗工された第一の光学フィルム２および第二の光学フィルム３（第一および第二の塗工機１０，１２の直後）における接着剤の塗工状態を、照明のもとで目視観察した。塗工された接着剤層端部の塗工状態を容易に目視観察できる場合を「良好」とし、目視観察が困難な場合を「不良」として、結果を表１に示した。 (Evaluation test)
[A] Visual observation inspection of adhesive application state First optical film 2 and second optical film 3 (first optical film) coated with an ultraviolet curable adhesive that passes through the chamber in the coating step (A) The adhesive coating state in the first and second coating machines 10 and 12) was visually observed under illumination. The results are shown in Table 1 where “good” indicates that the coated state of the coated adhesive layer end can be easily visually observed, and “bad” indicates that visual observation is difficult.
　実施例１および比較例２では、接着剤層端部の塗工状態を容易に目視観察することができたが、比較例１では目視観察できなかった。 In Example 1 and Comparative Example 2, the coating state of the adhesive layer end could be easily visually observed, but in Comparative Example 1, it was not visually observed.
　〔ｂ〕ふき取り試験
　上記実施例または各比較例で用いた照明のもとで、第一の光学フィルム２に用いたシクロオレフィン系樹脂フィルムを、３００ｍｍ（ＭＤ方向）×２００ｍｍ（ＴＤ方向）に切り出した後、一方の表面を上向きに机上に設置し、上記紫外線硬化型接着剤をスポイドにより直径３ｍｍの半球状に５滴滴下した。その状態で４１時間室温で放置した後、旭化成せんい（株）製の高品位ワイパー「ベンコットＭ－３ＩＩ」で拭き取り、その後、ベンコットＭ－３ＩＩにエタノールを染み込ませ、再度拭き取りを実施した。接着剤が除去できた場合を「良好」とし、接着剤が残る、あるいは拡がって除去できない場合は「不良」として、結果を表１に示した。この実験で拭き取りが「良好」となった場合は、偏光板の製造工程において積層体の端面から未硬化の紫外線硬化型接着剤がはみ出し、これがガイドロール等に付着した場合においても、容易に拭き取り除去が可能であり、製造工程の稼働率を著しく低下させることなく効率良く偏光板を製造することができる。 [B] Wiping test Under the illumination used in the above examples or comparative examples, the cycloolefin-based resin film used for the first optical film 2 was cut into 300 mm (MD direction) × 200 mm (TD direction). Then, one surface was placed on a desk face up, and 5 drops of the ultraviolet curable adhesive were dropped into a hemisphere with a diameter of 3 mm using a spoid. In this state, the mixture was allowed to stand at room temperature for 41 hours, and then wiped with a high-quality wiper “Bencot M-3II” manufactured by Asahi Kasei Fibers Co., Ltd. After that, ethanol was soaked into Bencott M-3II and wiped again. The results are shown in Table 1 as “good” when the adhesive could be removed and as “bad” when the adhesive remained or could not be removed due to spreading. If wiping is "good" in this experiment, even if the uncured UV-curing adhesive protrudes from the end face of the laminate in the manufacturing process of the polarizing plate and adheres to the guide roll, etc. The polarizing plate can be removed efficiently and the polarizing plate can be efficiently produced without significantly reducing the operating rate of the production process.
　実施例１および比較例１では、接着剤の固化成分も存在せず、容易に接着剤を除去することができた。これに対し、比較例２では、拭き取り後も接着剤の液滴の形が残り、これを除去することはできなかった。 In Example 1 and Comparative Example 1, there was no adhesive solidifying component, and the adhesive could be easily removed. On the other hand, in Comparative Example 2, the shape of the adhesive droplet remained even after wiping, and this could not be removed.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　１　偏光フィルム、２　第一の光学フィルム、３　第二の光学フィルム、４　偏光板、１０　第一の塗工機、１１　グラビアロール、１２　第二の塗工機、１３　グラビアロール、１４　紫外線照射装置、１５　照度計、２０，２１　貼合用ニップロール、２２，２３　巻取り前ニップロール、２４　ガイドロール、３０　巻取りロール、３１，３２　ロール体、４０，４１，４２，４３　ＬＥＤ照明。 DESCRIPTION OF SYMBOLS 1 Polarizing film, 2nd optical film, 3rd optical film, 4 Polarizing plate, 10 1st coating machine, 11 Gravure roll, 12 2nd coating machine, 13 Gravure roll, 14 Ultraviolet irradiation apparatus 15 illuminometer, 20, 21 nip roll for bonding, 22, 23 nip roll before winding, 24 guide roll, 30 winding roll, 31, 32 roll body, 40, 41, 42, 43 LED illumination.

Claims (4)

  1. 　ポリビニルアルコール系樹脂からなる偏光フィルムに、紫外線硬化型接着剤を介して熱可塑性樹脂からなる光学フィルムを貼合して、偏光板を製造する方法であって、
    　（Ａ）前記偏光フィルムおよび前記光学フィルムの少なくとも一方の貼合面に前記紫外線硬化型接着剤を塗工する塗工工程、
    　（Ｂ）塗工された前記紫外線硬化型接着剤を介して前記偏光フィルムと前記光学フィルムとを重ね合わせて積層体を得る貼合工程、および
    　（Ｃ）前記積層体に紫外線を照射して前記紫外線硬化型接着剤を硬化させる紫外線照射工程
    を含み、
    　前記塗工工程（Ａ）、前記貼合工程（Ｂ）および前記紫外線照射工程（Ｃ）が、４００ｎｍを超える波長域に発光波長を有し、２５０～４００ｎｍの波長域に発光波長を有しないＬＥＤ照明のもとで実施される偏光板の製造方法。     A method of manufacturing a polarizing plate by bonding an optical film made of a thermoplastic resin to a polarizing film made of a polyvinyl alcohol resin through an ultraviolet curable adhesive,
    (A) a coating step of applying the ultraviolet curable adhesive to at least one bonding surface of the polarizing film and the optical film;
    (B) A laminating step of obtaining a laminate by superimposing the polarizing film and the optical film through the coated ultraviolet curable adhesive, and (C) irradiating the laminate with ultraviolet rays, Including an ultraviolet irradiation step of curing the ultraviolet curable adhesive;
    LED in which the coating step (A), the bonding step (B), and the ultraviolet irradiation step (C) have a light emission wavelength in a wavelength region exceeding 400 nm and no light emission wavelength in a wavelength region of 250 to 400 nm A method for producing a polarizing plate carried out under illumination.
  2. 　前記塗工工程（Ａ）、前記貼合工程（Ｂ）および前記紫外線照射工程（Ｃ）が実施される１以上のチャンバ内に設けられた前記ＬＥＤ照明のもとで、前記塗工工程（Ａ）、前記貼合工程（Ｂ）および前記紫外線照射工程（Ｃ）が実施される、請求項１に記載の偏光板の製造方法。 Under the LED illumination provided in one or more chambers in which the coating step (A), the bonding step (B), and the ultraviolet irradiation step (C) are performed, the coating step (A ), The bonding step (B) and the ultraviolet irradiation step (C) are carried out.
  3. 　ポリビニルアルコール系樹脂からなる偏光フィルムに、紫外線硬化型接着剤を介して熱可塑性樹脂からなる光学フィルムを貼合して、偏光板を製造するための装置であって、
    　（Ａ１）前記偏光フィルムおよび前記光学フィルムの少なくとも一方の貼合面に前記紫外線硬化型接着剤を塗工するための塗工手段、
    　（Ｂ１）塗工された前記紫外線硬化型接着剤を介して前記偏光フィルムと光学フィルムとを重ね合わせて積層体を得るための貼合手段、
    　（Ｃ１）前記積層体に紫外線を照射して前記紫外線硬化型接着剤を硬化させるための紫外線照射手段、および
    　（Ｄ１）前記塗工手段（Ａ１）、前記貼合手段（Ｂ１）および前記紫外線照射手段（Ｃ１）を照明するための、４００ｎｍを超える波長域に発光波長を有し、２５０～４００ｎｍの波長域に発光波長を有しないＬＥＤ照明
    を備える偏光板製造装置。     An apparatus for producing a polarizing plate by bonding an optical film made of a thermoplastic resin to a polarizing film made of a polyvinyl alcohol-based resin via an ultraviolet curable adhesive,
    (A1) Coating means for applying the ultraviolet curable adhesive to at least one bonding surface of the polarizing film and the optical film,
    (B1) A bonding means for obtaining a laminate by superimposing the polarizing film and the optical film via the coated ultraviolet curable adhesive,
    (C1) Ultraviolet irradiation means for irradiating the laminate with ultraviolet rays to cure the ultraviolet curable adhesive, and (D1) The coating means (A1), the bonding means (B1), and the ultraviolet irradiation. An apparatus for producing a polarizing plate, comprising: LED illumination for illuminating the means (C1), having an emission wavelength in a wavelength range exceeding 400 nm and no emission wavelength in a wavelength range of 250 to 400 nm.
  4. 　前記塗工手段（Ａ１）、前記貼合手段（Ｂ１）および前記紫外線照射手段（Ｃ１）を収容するための１以上のチャンバをさらに備え、
    　前記チャンバ内に前記ＬＥＤ照明（Ｄ１）が設置される請求項３に記載の偏光板製造装置。     It further comprises one or more chambers for accommodating the coating means (A1), the bonding means (B1), and the ultraviolet irradiation means (C1),
    The polarizing plate manufacturing apparatus according to claim 3, wherein the LED illumination (D1) is installed in the chamber.
PCT/JP2013/056269 2012-03-29 2013-03-07 Polarizing plate fabrication method and fabrication apparatus WO2013146163A1 (en)

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JP2004245925A (en) * 2003-02-12 2004-09-02 Sumitomo Chem Co Ltd Polarizing plate, its manufacturing method, optical member, and liquid crystal display device
JP2009134190A (en) * 2007-11-30 2009-06-18 Sumitomo Chemical Co Ltd Method of manufacturing polarizing plate
JP2010033743A (en) * 2008-07-25 2010-02-12 Gc Corp Dental illuminating device
JP2012063321A (en) * 2010-09-17 2012-03-29 Hamamatsu Photonics Kk Reflectivity measurement device, reflectivity measurement method, film thickness measurement device, and film thickness measurement method

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