WO2015118975A1 - 偏光板及び表示装置 - Google Patents

偏光板及び表示装置 Download PDF

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Publication number
WO2015118975A1
WO2015118975A1 PCT/JP2015/051974 JP2015051974W WO2015118975A1 WO 2015118975 A1 WO2015118975 A1 WO 2015118975A1 JP 2015051974 W JP2015051974 W JP 2015051974W WO 2015118975 A1 WO2015118975 A1 WO 2015118975A1
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WO
WIPO (PCT)
Prior art keywords
protective film
film
polarizing plate
polarizer
resin
Prior art date
Application number
PCT/JP2015/051974
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English (en)
French (fr)
Japanese (ja)
Inventor
雄一朗 九内
Original Assignee
住友化学株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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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 KR1020167021500A priority Critical patent/KR102278332B1/ko
Priority to CN201580006789.4A priority patent/CN105940329B/zh
Publication of WO2015118975A1 publication Critical patent/WO2015118975A1/ja

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    • 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
    • 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
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/02—Non-macromolecular additives
    • C09J11/06—Non-macromolecular additives organic
    • 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
    • C09J201/00—Adhesives based on unspecified macromolecular compounds
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/50—Protective arrangements

Definitions

  • the present invention relates to a polarizing plate and a display device using the polarizing plate. More specifically, the polarizing plate is formed by bonding a protective film to at least one surface of a polarizer using an ultraviolet curable adhesive, and the polarizing plate. The present invention relates to the display device used.
  • the polarizing plate has been widely used in display devices such as liquid crystal display devices, especially in various mobile devices in recent years.
  • a polarizing plate the thing of the structure which bonded the protective film on the single side
  • a water-based adhesive or an ultraviolet curable adhesive is known as the adhesive, but a protective film with low moisture permeability has come to be preferred from the viewpoint of the water resistance of the polarizing plate.
  • ultraviolet curable adhesives have been used favorably because adhesion with water-based adhesives that require drying (removal of water by volatilization) has become difficult.
  • the protective film arranged on the most visible side when a liquid crystal display device is used contains an ultraviolet absorber.
  • the protective film placed on the most visible side may require retardation characteristics to ensure visibility when wearing sunglasses.
  • a stretched film made of polyethylene terephthalate resin is inexpensive. It is used suitably from a viewpoint.
  • UVB region a wavelength range of 280 to 320 nm (hereinafter referred to as “UVB region”) which is a general photosensitive wavelength region of a photopolymerization initiator contained in the ultraviolet curable adhesive.
  • the adhesive layer is cured by irradiating an ultraviolet ray containing “.”
  • a protective film containing an ultraviolet absorber absorbs most of the ultraviolet rays, it is difficult to cure the ultraviolet curable adhesive by irradiating ultraviolet rays from the protective film side.
  • a protective film made of a polyethylene terephthalate resin is also difficult to cure the ultraviolet curable adhesive because the aromatic ring contained in the resin skeleton substantially cuts the ultraviolet rays.
  • an antistatic agent may be added to the protective film arranged on the most visible side for the prevention of static charge.
  • the transmittance of ultraviolet rays further decreases. End up.
  • Liquid crystal coating type retardation films are often used. Most of the liquid crystal compounds that form the liquid crystal layer of the liquid crystal coating type retardation film absorb ultraviolet rays because the skeleton contains many aromatic rings. Since a retardation film made of polystyrene resin also contains an aromatic ring in the resin skeleton, it absorbs ultraviolet rays in the UVB region depending on the type of polystyrene resin used.
  • the above-mentioned Patent Document 1 contains an anthracene photosensitizer exhibiting maximum absorption in light having a wavelength longer than 380 nm in the ultraviolet curable adhesive. It has been proposed to let However, since this photosensitizer also has an absorption band in the visible region, it absorbs blue and the polarizing plate exhibits a yellowish color, or in an environment containing light of around 400 nm (under sunlight, under fluorescent light) If the polarizing plate is left for a long time under a mercury lamp, etc., the hue may change gradually. In addition, since the adhesive itself before curing has sensitivity to visible light, the polymerization gradually proceeds and thickens even under a normal fluorescent lamp or the like, that is, there is a risk of causing a problem that the pot life is short. there were.
  • Patent Document 2 described above describes that the content of an anthracene photosensitizer can be reduced by using a naphthalene photosensitizer together with an anthracene photosensitizer.
  • an anthracene photosensitizer is an essential component for realizing sufficient curing. Even if the content can be reduced to some extent, Patent Document 1 May still have the same problems as the UV curable adhesive described in.
  • the present invention has been made in view of the above, and its purpose is a polarizing plate in which a protective film is bonded to at least one surface of a polarizer via an adhesive layer made of an ultraviolet curable adhesive,
  • An object of the present invention is to provide a polarizing plate in which the adhesive layer is sufficiently cured even when the ultraviolet transmittance of the UVB region of the protective film is low, and a display device including the polarizing plate.
  • a further object of the present invention is to provide a polarizing plate that exhibits a yellowish color and does not cause a problem that the hue gradually changes when placed in an environment containing light of around 400 nm, and a display device including the same. There is.
  • the present inventor has sufficient adhesive when the protective film transmits ultraviolet rays in the UVB region even at a transmittance of only 1% in the integrated light amount in the region.
  • an absorption band is substantially formed in a wavelength region exceeding 380 nm. It is possible to achieve sufficient curing just by including only the photosensitizer that is not necessary, and simultaneously solve the above-mentioned problems caused by adding an anthracene photosensitizer having an absorption band in the visible region. I found out that I can do it.
  • the present invention provides the following polarizing plate and display device.
  • a polarizer and a first protective film laminated on one surface of the polarizer via a first adhesive layer The first protective film has a transmittance of accumulated light amount of 1 to 50% in a wavelength range of 280 to 320 nm
  • the first adhesive layer is composed of a cured product of an ultraviolet curable adhesive containing a photosensitizer,
  • the photosensitizer has an absorption band in at least a part of the wavelength range of 280 to 380 nm, and has substantially no absorption band in a wavelength range exceeding 380 nm. .
  • the second protective film has an accumulated light amount transmittance of 1 to 50% in a wavelength range of 280 to 320 nm
  • the second adhesive layer comprises a cured product of an ultraviolet curable adhesive containing a photosensitizer
  • the photosensitizer has an absorption band in at least a part of the wavelength range of 280 to 380 nm and substantially does not have an absorption band in a wavelength range exceeding 380 nm.
  • a display device comprising the polarizing plate according to any one of [1] to [8].
  • a polarizing plate in which a protective film having a low UV transmittance in the UVB region is bonded to a polarizer via an adhesive layer made of a cured product of an ultraviolet curable adhesive, Can be sufficiently cured, and can provide a polarizing plate that does not exhibit a problem of yellowishness or change in hue over time, and a display device including the polarizing plate.
  • FIG. 1 is a schematic cross-sectional view showing an example of a layer configuration of a polarizing plate according to the present invention.
  • a polarizing plate of the present invention like the polarizing plate 1 shown in FIG. 1 includes a polarizer 5 and a single-side protection provided with a first protective film 10 laminated on one surface of the polarizing plate 1 with a first adhesive layer 15 interposed therebetween. It can be a polarizing plate with a film.
  • the polarizing plate 1 can further have another optical functional layer, an adhesive layer, or the like laminated on the first protective film 10 and / or the polarizer 5.
  • the polarizing plate of this invention is the same as the polarizing plate 2 shown in FIG. 2, the polarizer 5, the 1st protective film 10 laminated
  • stacked through the 2nd adhesive bond layer 25 on the surface of this may be sufficient.
  • the polarizing plate 2 can further include other optical functional layers and pressure-sensitive adhesive layers that are laminated on the first protective film 10 and / or the second protective film 20.
  • the first protective film 10 has a wavelength region of 280 to 320 nm, which is a general photosensitive wavelength region of the photopolymerization initiator contained in the ultraviolet curable adhesive forming the first adhesive layer 15 ( UVB region) is a film having a low transmittance, and specifically, a film having a cumulative light amount transmittance of 50% or less (and 1% or more) in the UVB region.
  • the first adhesive layer 15 is a layer formed from an ultraviolet curable adhesive containing only a predetermined photosensitizer as a photosensitizer, and specifically, a cured product layer of the ultraviolet curable adhesive. It is.
  • the predetermined photosensitizer is a photosensitizer having an absorption band in at least a part of the wavelength range of 280 to 380 nm and substantially having no absorption band in a wavelength range exceeding 380 nm. It is.
  • the 2nd protective film 20 which the polarizing plate 2 with a double-sided protective film has may be arbitrary films which can be used as a protective film for polarizers, and the 2nd adhesive bond layer 25 for bonding this is also the polarizer 5. It may be a layer made of any adhesive that can bond the second protective film 20 and the second protective film 20. However, the transmittance
  • the ultraviolet curable adhesive forming the second adhesive layer 25 is the same as the first adhesive layer 15 as the photosensitizer described above. It is preferable to contain only the photosensitizer.
  • the polarizer 5 can be obtained by adsorbing and orienting a dichroic dye on a uniaxially stretched polyvinyl alcohol resin layer (or film).
  • the thickness of the polarizer 5 can be, for example, 30 ⁇ m or less, and further 20 ⁇ m or less. Particularly, in the polarizing plate for mobile devices, the thickness is preferably 10 ⁇ m or less from the viewpoint of thinning the polarizing plates 1 and 2. More preferably, it is 8 ⁇ m or less.
  • the thickness of the polarizer 5 is usually 2 ⁇ m or more.
  • a saponified polyvinyl acetate resin can be used as the polyvinyl alcohol resin constituting the polyvinyl alcohol resin layer.
  • the polyvinyl acetate-based resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith.
  • examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.
  • the film made of the polyvinyl alcohol resin constitutes the polarizer 5.
  • the method for forming the polyvinyl alcohol-based resin is not particularly limited and can be formed by a known method. However, it is easy to obtain a polarizer 5 having a small thickness, and the thin-film polarizer 5 is handled in the process. In view of excellent properties, it is preferable to form a film by applying a solution of a polyvinyl alcohol-based resin on a base film.
  • the degree of saponification of the polyvinyl alcohol-based resin can be in the range of 80.0 to 100.0 mol%, preferably in the range of 90.0 to 99.5 mol%, more preferably 94.0. It is in the range of ⁇ 99.0 mol%.
  • the degree of saponification is less than 80.0 mol%, the water resistance and heat-and-moisture resistance of the obtained polarizing plates 1 and 2 are lowered.
  • a polyvinyl alcohol-based resin having a saponification degree exceeding 99.5 mol% is used, the dyeing speed becomes slow, the productivity decreases, and the polarizer 5 having sufficient polarization performance may not be obtained.
  • the degree of saponification is the unit ratio (mol%) of the ratio of acetate groups (acetoxy groups: —OCOCH 3 ) contained in polyvinyl acetate resin, which is a raw material for polyvinyl alcohol resins, to hydroxyl groups by the saponification process.
  • the following formula: Saponification degree (mol%) 100 ⁇ (number of hydroxyl groups) ⁇ (number of hydroxyl groups + number of acetate groups) Defined by The saponification degree can be determined according to JIS K 6726 (1994). The higher the degree of saponification, the higher the proportion of hydroxyl groups, and thus the lower the proportion of acetate groups that inhibit crystallization.
  • the polyvinyl alcohol resin may be a modified polyvinyl alcohol partially modified.
  • polyvinyl alcohol resins modified with olefins such as ethylene and propylene; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; alkyl esters of unsaturated carboxylic acids, acrylamide, and the like can be used.
  • the proportion of modification is preferably less than 30 mol%, and more preferably less than 10%. When modification exceeding 30 mol% is performed, it becomes difficult to adsorb the dichroic dye, and the polarizer 5 having sufficient polarization performance cannot be obtained.
  • the average degree of polymerization of the polyvinyl alcohol-based resin is preferably 100 to 10,000, more preferably 1500 to 8000, and further preferably 2000 to 5000.
  • the average degree of polymerization of the polyvinyl alcohol resin can also be determined according to JIS K 6726 (1994).
  • the dichroic dye contained (adsorption orientation) in the polarizer 5 can be iodine or a dichroic organic dye.
  • the dichroic organic dye include: Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Includes Sky Blue, Direct First Orange S and First Black.
  • a dichroic dye may be used individually by 1 type, and may use 2 or more types together.
  • the 1st protective film 10 is a thermoplastic resin which has translucency (preferably optically transparent), for example, chain polyolefin resin (polypropylene resin etc.), cyclic polyolefin resin Polyolefin resins such as (norbornene resins); cellulose ester resins such as cellulose triacetate and cellulose diacetate; polyester resins; polycarbonate resins; (meth) acrylic resins; polystyrene resins; or a mixture thereof And a film made of a copolymer or the like.
  • chain polyolefin resin polypropylene resin etc.
  • cyclic polyolefin resin Polyolefin resins such as (norbornene resins); cellulose ester resins such as cellulose triacetate and cellulose diacetate; polyester resins; polycarbonate resins; (meth) acrylic resins; polystyrene resins; or a mixture thereof
  • a film made of a copolymer or the like a
  • the first protective film 10 preferably used in the present invention is a protective film having low moisture permeability that is difficult to adhere with an aqueous adhesive, such as polyolefin resin, polyester resin, (meth) acrylic resin, polystyrene resin, and the like. It is a protective film.
  • (meth) acryl means at least one selected from acrylic and methacrylic. The same applies to cases such as “(meth) acryloyl” and “(meth) acrylate”.
  • the first protective film 10 can also be a protective film having both optical functions such as a retardation film and a brightness enhancement film.
  • a retardation film provided with an arbitrary retardation value by stretching a film made of the thermoplastic resin (uniaxial stretching or biaxial stretching) or by forming a liquid crystal layer or the like on the film. It can be.
  • chain polyolefin resin examples include a homopolymer of a chain olefin such as a polyethylene resin and a polypropylene resin, and a copolymer composed of two or more chain olefins.
  • Cyclic polyolefin-based resin is a general term for resins that are polymerized using cyclic olefins as polymerization units.
  • Specific examples of cyclic polyolefin resins include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins and chain olefins such as ethylene and propylene (typically Are random copolymers), graft polymers obtained by modifying them with unsaturated carboxylic acids or derivatives thereof, and hydrides thereof.
  • norbornene resins using norbornene monomers such as norbornene and polycyclic norbornene monomers as cyclic olefins are preferably used.
  • the cellulose ester resin is an ester of cellulose and a fatty acid.
  • Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate.
  • these copolymers and those in which a part of the hydroxyl group is modified with other substituents can also be used.
  • cellulose triacetate triacetyl cellulose: TAC is particularly preferable.
  • the polyester-based resin is a resin having an ester bond, and is generally made of a polycondensate of a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol.
  • a polyvalent carboxylic acid or a derivative thereof a divalent dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate.
  • a divalent diol can be used, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol.
  • polyester resin examples include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethyl terephthalate, and polycyclohexanedimethyl naphthalate.
  • Polycarbonate resin is made of a polymer in which monomer units are bonded via a carbonate group.
  • the polycarbonate-based resin may be a resin called a modified polycarbonate having a modified polymer skeleton, a copolymer polycarbonate, or the like.
  • the (meth) acrylic resin is a resin containing a compound having a (meth) acryloyl group as a main constituent monomer.
  • Specific examples of the (meth) acrylic resin include, for example, poly (meth) acrylic acid esters such as polymethyl methacrylate; methyl methacrylate- (meth) acrylic acid copolymer; methyl methacrylate- (meth) acrylic acid Ester copolymer; methyl methacrylate-acrylate ester- (meth) acrylic acid copolymer; (meth) methyl acrylate-styrene copolymer (MS resin, etc.); methyl methacrylate and alicyclic hydrocarbon group And a copolymer with the compound (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.).
  • a polymer based on a poly (meth) acrylic acid C 1-6 alkyl ester such as poly (meth) acrylic acid methyl is used, and more preferably methyl methacrylate is used as a main component (50 to 100). % Methyl methacrylate-based resin is used.
  • a surface treatment layer such as a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an antifouling layer is formed on the surface of the first protective film 10 opposite to the polarizer 5. You can also.
  • the method for forming the surface treatment layer on the surface of the protective film is not particularly limited, and a known method can be used.
  • the thickness of the first protective film 10 is preferably thin from the viewpoint of reducing the thickness of the polarizing plates 1 and 2, but if it is too thin, the strength is lowered and the processability is poor. Accordingly, the thickness of the first protective film 10 is preferably 5 to 90 ⁇ m or less, more preferably 5 to 60 ⁇ m, and still more preferably 5 to 50 ⁇ m.
  • the first protective film 10 is a film having a low transmittance in the region of 280 to 320 nm (UVB region), specifically, a film having a transmittance of 50% or less of the integrated light quantity in the UVB region.
  • the UVB region is included from the first protective film 10 side even if it is 30% or less, 20% or less, 10% or less, and even 5% or less.
  • the first adhesive layer 15 can be sufficiently cured by irradiation with ultraviolet rays. When the transmittance is less than 1%, the irradiated ultraviolet rays hardly reach the adhesive layer, and even if the ultraviolet curable adhesive contains a photosensitizer, sufficient curing cannot be obtained.
  • the degree of curing of the adhesive layer can be evaluated by, for example, a wet heat durability test. Although a specific test method will be described in the section of the examples, if the curing is insufficient, the polarizer 5 is decolored or spotted unevenness under a wet heat durability test.
  • the transmittance of the integrated light quantity in the UVB region of the first protective film 10 (the same applies to the second protective film 20) is obtained by the following method.
  • the measuring device is not limited as long as it can be obtained by integrating the light intensity in the wavelength range of 280 to 320 nm.
  • Electronic Instrumentation & Technology, Inc. "UV Power Pack 2" etc. sold from
  • the light from the light source (adhesive layer curing ultraviolet light source) is directly measured using the measuring apparatus, and the integrated light amount (mJ / cm 2 ) in the UVB region is defined as “reference integrated light amount”.
  • the integrated light amount (mJ / cm 2 ) in the UVB region is defined as “reference integrated light amount”.
  • the peak intensity of the light source is preferably in the range of 150 to 250 mW / cm 2 .
  • the reference integrated light quantity is preferably in the range of 100 to 400 mJ / cm 2 .
  • the following is a specific example of the first protective film 10 in which the transmittance of the integrated light quantity in the UVB region is 1 to 50%.
  • [A] Protective film containing an ultraviolet absorber (including the case of a protective film having an optical function such as a retardation film and a brightness enhancement film. The same applies to [b] and [c] below).
  • UV absorber in the above [a] for example, 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] 2- (5-methyl-2-hydroxyphenyl) -2H-benzotriazole, 2- [2-hydroxy-3,5-bis ( ⁇ , ⁇ -dimethylbenzyl) phenyl] -2H-benzotriazole, 2- ( 3,5-di-tert-butyl-2-hydroxyphenyl) -2H-benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chloro-2H-benzotriazole, 2 -(3,5-di-t-butyl-2-hydroxyphenyl) -5-chloro-2H-benzotriazole, 2- (3,5-di-t-amyl-2-hydroxypheny ) -2H-benzotriazole, benzotriazole ultraviolet absorbers such
  • the support film in the above [d] can be a film made of the above-mentioned thermoplastic resin.
  • the liquid crystal layer is a layer obtained by aligning, curing and fixing a liquid crystal compound, which is laminated on a support film through an alignment layer as necessary.
  • the liquid crystal compound can be a polymerizable liquid crystal compound containing a biphenyl group or a mesogen group.
  • the polarizing plate (the polarizing plate 1 with a single-sided protective film and the polarizing plate 2 with a double-sided protective film) of this invention may be a polarizing plate arrange
  • the first protective film 10 may be a polarizing plate disposed on the back side (backlight side), and the polarizing plate of the present invention is a polarizing plate on either the front side or the back side. It can be a protective film laminated on the liquid crystal cell side of the polarizer 5 or a protective film laminated on the opposite side of the liquid crystal cell.
  • the first protective film 10 (especially in the polarizing plate 2 with a double-sided protective film) is a protective film laminated on the liquid crystal cell side of the polarizer 5, the above-mentioned [b] ] Or [d].
  • the first protective film 10 is a protective film laminated on the side opposite to the liquid crystal cell of the polarizer 5 (for example, when it is a protective film on the viewing side of the front polarizing plate)
  • the above [a] to [ Among these, the protective film or retardation film belonging to the above [a] to [c] can be used.
  • the first adhesive layer 15 is a cured product layer of an ultraviolet curable adhesive containing a photosensitizer.
  • the thickness of the first adhesive layer 15 is usually about 0.001 to 5 ⁇ m, preferably 0.01 to 2 ⁇ m, more preferably 0.01 to 1 ⁇ m.
  • the ultraviolet curable adhesive contains a curable compound (polymerizable compound), a photopolymerization initiator, and a photosensitizer.
  • the photosensitizer is a photosensitizer having an absorption band in at least a part of the wavelength range of 280 to 380 nm and substantially having no absorption band in the wavelength range exceeding 380 nm. Use the agent. Two or more photosensitizers can be used as long as they exhibit such light absorption characteristics.
  • the present invention is characterized by the use of a photosensitizer having the above-described light absorption characteristics. This is because the protective film has a UVB transmittance of only 1%, even if the protective film has a transmittance of only 1%. In the case of transmitting ultraviolet light in the region, only a photosensitizer having an absorption band in the wavelength range of 280 to 380 nm is used without using a photosensitizer having an absorption band longer than 380 nm. This is based on the surprising discovery of the present inventor that the adhesive layer made of the ultraviolet curable adhesive can be sufficiently cured by the ultraviolet irradiation from the protective film side.
  • a photosensitizer having an absorption band on the longer wavelength side than 380 nm is not used. This makes it possible to absorb the blue color and the polarizing plate (adhesive layer) becomes yellowish, or when the polarizing plate is left in an environment containing light of around 400 nm for a long time, the hue gradually changes. It is possible to eliminate problems such as illusion, and to provide a polarizing plate with excellent light resistance.
  • the ultraviolet curable adhesive according to the present invention containing only a photosensitizer having an absorption band in the wavelength range of 280 to 380 nm as a photosensitizer, discoloration with time under external light, It is also possible to prevent the progress of polymerization and the accompanying thickening when left under a fluorescent lamp or LED light for a long period of time.
  • the photosensitizer used in the present invention may have an absorption band in at least a part of the wavelength range of 280 to 380 nm.
  • the photosensitizer used in combination has a general photosensitive wavelength range (absorption).
  • the wavelength range (280 to 320 nm) is preferably overlapped to some extent with the absorption band of the photosensitizer, so that the photosensitizer absorbs at least within the wavelength range of 280 to 320 nm. It is preferable to have a belt.
  • the efficiency of light from a general ultraviolet light source irradiated to the adhesive layer through the first protective film 10 when the absorption band is slightly longer than the wavelength range of 280 to 320 nm.
  • the photosensitizer preferably has an absorption band in the wavelength range of 320 to 380 nm in addition to the wavelength range of 280 to 320 nm.
  • the photosensitizer has a continuous absorption band extending over a wavelength of 320 nm in the wavelength range of 280 to 380 nm.
  • the photosensitizer used in the present invention has substantially no absorption band in the wavelength region exceeding 380 nm. “Substantially” means that the absorbance in the wavelength region exceeding 380 nm is less than 1/50 of the maximum absorbance exhibited by the sensitizer, as measured by an absorptiometer.
  • naphthalene derivatives can be preferably used as the photosensitizer having the above light absorption properties. Specific examples thereof include 1,4-dimethoxynaphthalene, 1-ethoxy-4-methoxynaphthalene, 1,4- Diethoxynaphthalene, 1,4-dibutoxynaphthalene, 1,4-dipropoxynaphthalene and the like are included.
  • the content of the photosensitizer in the ultraviolet curable adhesive is preferably 0.1 to 10 parts by weight, and preferably 0.3 to 5.0 parts by weight with respect to 100 parts by weight of the curable compound. More preferred is 0.5 to 3.0 parts by weight. If the amount of the sensitizer is too small, curing of the adhesive may be insufficient. If the amount is too large, the photosensitizer may not be completely dissolved; the content of the curable compound and the photopolymerization initiator may be relatively decreased. This can cause problems in curing the adhesive layer; it can cause problems such as increased costs.
  • Examples of the curable compound contained in the ultraviolet curable adhesive include epoxy compounds that are cured by cationic polymerization (compounds having an average of 1 or more, preferably 2 or more epoxy groups in the molecule), and curing by radical polymerization. (Meth) acrylic compounds to be used can be used.
  • an epoxy compound that can be suitably used is a hydrogenated epoxy compound (aliphatic compound) obtained by reacting an alicyclic polyol obtained by hydrogenating an aromatic ring of an aromatic polyol with epichlorohydrin.
  • a glycidyl ether of a cyclic polyol an aliphatic epoxy compound such as an aliphatic polyhydric alcohol or a polyglycidyl ether of an alkylene oxide adduct thereof; including an alicyclic epoxy compound having at least one epoxy group in the molecule .
  • the epoxy compound the epoxy compounds described in Patent Documents 1 and 2 can also be used.
  • the (meth) acrylic compound is obtained by reacting at least one (meth) acrylate monomer having at least one (meth) acryloyloxy group in the molecule; two or more functional group-containing compounds.
  • Examples include (meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers having one (meth) acryloyloxy group.
  • the ultraviolet curable adhesive contains a photocationic polymerization initiator.
  • the photocationic polymerization initiator include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-allene complexes.
  • the ultraviolet curable adhesive contains a radical polymerizable curable compound such as a (meth) acrylic compound, it contains a photo radical polymerization initiator.
  • photo radical polymerization initiator examples include acetophenone initiator, benzophenone initiator, benzoin ether initiator, thioxanthone initiator, xanthone, fluorenone, camphorquinone, benzaldehyde, anthraquinone and the like.
  • the content of the photopolymerization initiator in the ultraviolet curable adhesive (the total amount of the photocationic polymerization initiator and the radical photopolymerization initiator) is usually 0.5 to 20 parts by weight with respect to 100 parts by weight of the curable compound. Yes, preferably 1 part by weight or more, and preferably 15 parts by weight or less. If the photopolymerization initiator is too small, curing of the adhesive will be insufficient, and if it is too large, the ionic substance in the cured product will increase, increasing the hygroscopicity of the cured product and reducing the durability of the polarizing plate. there is a possibility.
  • UV curable adhesives if necessary, cationic polymerization accelerators such as oxetanes and polyols, ion trapping agents, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow regulators Further, additives such as a plasticizer, an antifoaming agent, an antistatic agent, a leveling agent and a solvent can be contained. As an additive, what was illustrated by the said patent document 1 and 2 may be used if needed.
  • the 2nd protective film 20 which the polarizing plate 2 with a double-sided protective film has can be a film which consists of the above-mentioned thermoplastic resin similarly to the 1st protective film 10, a retardation film, brightness
  • the first protective film 10 and the second protective film 20 may be the same type of protective film or different types of protective films.
  • examples of the second protective film 20 suitably used in the present invention include a protective film having low moisture permeability that is difficult to adhere with an aqueous adhesive, such as a polyolefin resin, a polyester resin, a (meth) acrylic resin, and a polystyrene resin. It is a protective film consisting of etc.
  • the second protective film 20 may be a film having a transmittance of accumulated light in the UVB region of 1 to 50%.
  • the above-described ultraviolet curable adhesive containing a photosensitizer exhibiting a predetermined light absorption characteristic similar to the first adhesive layer 15, for the second adhesive layer 25.
  • the description of the first protective film 10 is cited.
  • the second protective film 20 in which the transmittance of the integrated light amount in the UVB region is 1 to 50% are the above [a] to [d], similar to the first protective film 10.
  • the first protective film 10 is, for example, a protective film laminated on the liquid crystal cell side of the polarizer 5
  • the second protective film 20 is on the opposite side of the liquid crystal cell of the polarizer 5.
  • the second protective film 20 can be, for example, a protective film or a retardation film belonging to [a] to [c].
  • the 2nd protective film 20 is a protective film laminated
  • the second protective film 20 can be, for example, a retardation film belonging to the above [b] or [d].
  • the second adhesive layer 25 is a layer for adhering the second protective film 20 to the polarizer 5.
  • the adhesive that forms the second adhesive layer 25 is not particularly limited, and is an active energy ray-curable adhesive that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays, and an adhesive component. May be a water-based adhesive in which water is dissolved or dispersed, but particularly when the second protective film 20 has low moisture permeability, an active energy ray-curable adhesive is preferably used, and an ultraviolet-curable adhesive is used. More preferably used.
  • the second adhesive layer 25 can be sufficiently cured by ultraviolet irradiation from the second protective film 20 side.
  • the above-described ultraviolet curable adhesive containing a photosensitizer exhibiting a predetermined light absorption characteristic, similar to the first adhesive layer 15, for the second adhesive layer 25 is preferable to use the above-described ultraviolet curable adhesive containing a photosensitizer exhibiting a predetermined light absorption characteristic, similar to the first adhesive layer 15, for the second adhesive layer 25.
  • the second adhesive layer 25 also does not contain a photosensitizer having an absorption band longer than 380 nm, the coloration of the polarizing plate caused by the second adhesive layer 25 and the time-lapse Discoloration can also be prevented.
  • water-based adhesive examples include an adhesive made of a polyvinyl alcohol-based resin aqueous solution and a water-based two-component urethane emulsion adhesive.
  • a water-based adhesive composed of a polyvinyl alcohol-based resin aqueous solution is preferably used.
  • Adhesive layer On the polarizer 5 in the polarizing plate 1 with a single-sided protective film shown in FIG. 1, or on the first protective film 10 or the second protective film 20 in the polarizing plate 2 with a double-sided protective film shown in FIG. Moreover, you may laminate
  • the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is usually based on a (meth) acrylic resin, styrene resin, silicone resin or the like, and a crosslinking agent such as an isocyanate compound, an epoxy compound, or an aziridine compound is added thereto. It consists of an adhesive composition. Furthermore, it can also be set as the adhesive layer which contains microparticles
  • the thickness of the pressure-sensitive adhesive layer is usually 1 to 40 ⁇ m, preferably 3 to 25 ⁇ m.
  • the polarizing plates 1 and 2 can further include other optical layers laminated on the protective films 10 and 20 and the polarizer 5.
  • a reflective polarizing film that transmits a certain kind of polarized light and reflects polarized light that exhibits the opposite properties
  • a film with an antiglare function having a concavo-convex shape on the surface
  • a film with a surface antireflection function A reflective film having a reflective function on the surface
  • a transflective film having both a reflective function and a transmissive function
  • a viewing angle compensation film is another optical layer.
  • the polarizing plate of the present invention is preferably manufactured by the method shown in FIG. 3 because the thin film polarizer 5 can be easily obtained.
  • the manufacturing method of the polarizing plate shown in FIG. (1) Resin layer forming step S10 in which a coating liquid containing a polyvinyl alcohol-based resin is applied to at least one surface of a base film and then dried to form a polyvinyl alcohol-based resin layer to obtain a laminated film.
  • Stretching step S20 to stretch the laminated film to obtain a stretched film
  • Dyeing step S30 to obtain a polarizing laminated film by dyeing the polyvinyl alcohol resin layer of the stretched film with a dichroic dye to form a polarizer
  • 1st bonding process S40 which bonds a protective film on the polarizer of a light-polarizing laminated film, and obtains a bonding film
  • Peeling step S50 to peel and remove the base film from the laminated film to obtain a polarizing plate with a single-sided protective film, Are included in this order.
  • the polyvinyl alcohol-based resin layer may be formed on both surfaces of the base film, but the case where it is mainly formed on one surface will be described below.
  • Resin layer forming step S10 is a step of obtaining laminated film 100 by forming polyvinyl alcohol-based resin layer 6 on at least one surface of base film 30.
  • the polyvinyl alcohol-based resin layer 6 is a layer that becomes the polarizer 5 through the stretching step S20 and the dyeing step S30.
  • the polyvinyl alcohol-based resin layer 6 can be formed by applying a coating liquid containing a polyvinyl alcohol-based resin to one or both surfaces of the base film 30 and drying the coating layer.
  • the method of forming a polyvinyl alcohol-based resin layer by such coating is advantageous in that a thin film polarizer 5 can be easily obtained.
  • the base film 30 can be composed of a thermoplastic resin, and is preferably composed of a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, stretchability and the like.
  • thermoplastic resins include, for example, polyolefin resins such as chain polyolefin resins and cyclic polyolefin resins (norbornene resins, etc.); polyester resins; (meth) acrylic resins; cellulose triacetate, Cellulose ester resins such as cellulose diacetate; Polycarbonate resins; Polyvinyl alcohol resins; Polyvinyl acetate resins; Polyarylate resins; Polystyrene resins; Polyethersulfone resins; Polysulfone resins; Polyamide resins; System resins; and mixtures and copolymers thereof.
  • the base film 30 may have a single-layer structure made of one resin layer made of one kind or two or more kinds of thermoplastic resins, or a plurality of resin layers made of one kind or two or more kinds of thermoplastic resins. A laminated multilayer structure may be used.
  • the base film 30 is preferably made of a resin that can be stretched at a stretching temperature suitable for stretching the polyvinyl alcohol-based resin layer 6 when the laminated film 100 is stretched in the stretching step S20 described later.
  • the base film 30 can contain an additive.
  • the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, an anti-coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent.
  • the content of the thermoplastic resin in the base film 30 is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. .
  • the thickness of the base film 30 is usually 1 to 500 ⁇ m, preferably 1 to 300 ⁇ m, more preferably 5 to 200 ⁇ m, and still more preferably 5 to 150 ⁇ m from the viewpoint of workability such as strength and handleability.
  • the coating liquid applied to the base film 30 is preferably a polyvinyl alcohol resin solution obtained by dissolving a polyvinyl alcohol resin powder in a good solvent (for example, water).
  • a good solvent for example, water
  • the details of the polyvinyl alcohol resin are as described above.
  • the coating liquid may contain additives such as a plasticizer and a surfactant as necessary.
  • the coating liquid is applied to the base film 30 by a wire bar coating method; a roll coating method such as reverse coating or gravure coating; a die coating method; a comma coating method; a lip coating method; a spin coating method;
  • the method can be appropriately selected from a method such as a fountain coating method, a dipping method, and a spray method.
  • the drying temperature and drying time of the coating layer are set according to the type of solvent contained in the coating solution.
  • the drying temperature is, for example, 50 to 200 ° C., preferably 60 to 150 ° C.
  • the drying temperature is preferably 80 ° C. or higher.
  • the polyvinyl alcohol-based resin layer 6 may be formed only on one side of the base film 30 or on both sides. When formed on both sides, curling of the film that can occur during the production of the polarizing laminated film 300 (see FIG. 6) can be suppressed, and two polarizing plates can be obtained from one polarizing laminated film 300. It is also advantageous in terms of plate production efficiency.
  • the thickness of the polyvinyl alcohol resin layer 6 in the laminated film 100 is preferably 3 to 30 ⁇ m, and more preferably 5 to 20 ⁇ m. If the polyvinyl alcohol-based resin layer 6 has a thickness within this range, the dichroic dye has good dyeability and excellent polarization performance through a stretching step S20 and a dyeing step S30 described later, and is sufficiently thin (for example, A polarizer 5 (thickness of 10 ⁇ m or less) can be obtained. If the thickness of the polyvinyl alcohol-based resin layer 6 is less than 3 ⁇ m, the film becomes too thin after stretching and the dyeability tends to deteriorate.
  • At least the surface of the base film 30 on the side where the polyvinyl alcohol resin layer 6 is formed is provided. Corona treatment, plasma treatment, flame (flame) treatment or the like may be performed.
  • the polyvinyl alcohol resin layer 6 Prior to coating the coating liquid, the polyvinyl alcohol resin layer 6 is provided on the base film 30 via a primer layer or the like in order to improve the adhesion between the base film 30 and the polyvinyl alcohol resin layer 6. May be formed.
  • the primer layer can be formed by applying a primer layer forming coating solution onto the surface of the base film 30 and then drying it.
  • the primer layer forming coating solution contains a component that exhibits a certain degree of strong adhesion to both the base film 30 and the polyvinyl alcohol-based resin layer 6.
  • the primer layer-forming coating solution usually contains a resin component that imparts such adhesion and a solvent.
  • a resin component a thermoplastic resin excellent in transparency, thermal stability, stretchability and the like is preferably used, and examples thereof include (meth) acrylic resins and polyvinyl alcohol resins. Among these, polyvinyl alcohol resins that give good adhesion are preferably used. More preferably, it is a polyvinyl alcohol resin.
  • As the solvent a general organic solvent or an aqueous solvent capable of dissolving the resin component is usually used, but it is preferable to form the primer layer from a coating solution containing water as a solvent.
  • a crosslinking agent may be added to the primer layer forming coating solution.
  • a suitable crosslinking agent is appropriately selected from known ones such as organic and inorganic based on the type of thermoplastic resin to be used.
  • crosslinking agents include, for example, epoxy-based, isocyanate-based, dialdehyde-based, metal-based (for example, metal salts, metal oxides, metal hydroxides, organometallic compounds), and polymer-based crosslinking agents. .
  • a polyvinyl alcohol resin is used as the resin component for forming the primer layer
  • a polyamide epoxy resin, a methylolated melamine resin, a dialdehyde crosslinking agent, a metal chelate compound crosslinking agent, or the like is preferably used.
  • the thickness of the primer layer is preferably about 0.05 to 1 ⁇ m, more preferably 0.1 to 0.4 ⁇ m.
  • the thickness is less than 0.05 ⁇ m, the effect of improving the adhesion between the base film 30 and the polyvinyl alcohol-based resin layer 6 is small, and when the thickness is more than 1 ⁇ m, it is disadvantageous for thinning the polarizing plate.
  • the method of applying the primer layer forming coating solution to the base film 30 can be the same as the coating solution for forming the polyvinyl alcohol-based resin layer.
  • the primer layer is applied to the surface on which the coating liquid for forming the polyvinyl alcohol-based resin layer is applied.
  • the drying temperature of the coating layer made of the primer layer forming coating solution is, for example, 50 to 200 ° C., and preferably 60 to 150 ° C. When the solvent contains water, the drying temperature is preferably 80 ° C. or higher.
  • Stretching step S20 With reference to FIG. 5, this process extends
  • the stretching process is usually uniaxial stretching.
  • the stretching ratio of the laminated film 100 can be appropriately selected depending on the desired polarization characteristics, but is preferably more than 5 times and not more than 17 times, more preferably more than 5 times the original length of the laminated film 100. 8 times or less. If the draw ratio is 5 times or less, the polyvinyl alcohol resin layer 6 ′ is not sufficiently oriented, and the degree of polarization of the polarizer 5 may not be sufficiently high. On the other hand, when the draw ratio exceeds 17 times, the film is likely to be broken during stretching, and the thickness of the stretched film 200 becomes unnecessarily thin, and the workability and handleability in subsequent processes may be reduced.
  • the stretching process is not limited to one-stage stretching, and can be performed in multiple stages.
  • all of the multistage stretching processes may be performed continuously before the dyeing process S30, or the second and subsequent stretching processes may be performed simultaneously with the dyeing process and / or the crosslinking process in the dyeing process S30.
  • the stretching treatment may be longitudinal stretching that extends in the film longitudinal direction (film transport direction), and may be lateral stretching or oblique stretching that extends in the film width direction.
  • the longitudinal stretching method include inter-roll stretching using a roll, compression stretching, stretching using a chuck (clip), and the like
  • examples of the lateral stretching method include a tenter method.
  • the stretching treatment either a wet stretching method or a dry stretching method can be adopted. However, it is preferable to use the dry stretching method because the stretching temperature can be selected from a wide range.
  • the stretching temperature is set to be equal to or higher than the temperature at which the polyvinyl alcohol-based resin layer 6 and the entire base film 30 can be stretched, and preferably the phase transition temperature (melting point or glass transition temperature) of the base film 30. It is in the range of ⁇ 30 ° C. to + 30 ° C., more preferably in the range of ⁇ 30 ° C. to + 5 ° C., and still more preferably in the range of ⁇ 25 ° C. to + 0 ° C.
  • the phase transition temperature means the highest phase transition temperature among the phase transition temperatures exhibited by the plurality of resin layers.
  • the stretching temperature is lower than the phase transition temperature of ⁇ 30 ° C., it is difficult to achieve a high-magnification stretching of more than 5 times, or the fluidity of the base film 30 is too low and the stretching process tends to be difficult.
  • the stretching temperature exceeds + 30 ° C. of the phase transition temperature, the fluidity of the base film 30 is too large and stretching tends to be difficult. Since it is easier to achieve a high draw ratio of more than 5 times, the drawing temperature is within the above range, and more preferably 120 ° C. or higher.
  • a zone heating method for example, a method in which hot air is blown and heated in a stretching zone such as a heating furnace adjusted to a predetermined temperature
  • a heater heating method a method in which infrared heaters, halogen heaters, panel heaters, etc. are installed above and below the laminated film 100 and heated by radiant heat.
  • the zone heating method is preferable from the viewpoint of the uniformity of the stretching temperature.
  • a preheat treatment step for preheating the laminated film 100 may be provided.
  • the preheating method the same method as the heating method in the stretching process can be used.
  • the preheating temperature is preferably in the range of ⁇ 50 ° C. to ⁇ 0 ° C. of the stretching temperature, and more preferably in the range of ⁇ 40 ° C. to ⁇ 10 ° C. of the stretching temperature.
  • a heat setting treatment step may be provided after the stretching treatment in the stretching step S20.
  • the heat setting process is a process in which heat treatment is performed at a temperature equal to or higher than the crystallization temperature while maintaining the tensioned state with the end of the stretched film 200 held by a clip.
  • the crystallization of the polyvinyl alcohol-based resin layer 6 ' is promoted by this heat setting treatment.
  • the temperature of the heat setting treatment is preferably in the range of ⁇ 0 ° C. to ⁇ 80 ° C. of the stretching temperature, and more preferably in the range of ⁇ 0 ° C. to ⁇ 50 ° C. of the stretching temperature.
  • this step is a step in which the polarizer 5 is obtained by dyeing the polyvinyl alcohol resin layer 6 ′ of the stretched film 200 with a dichroic dye and adsorbing and orienting it. Through this step, a polarizing laminated film 300 in which the polarizer 5 is laminated on one side or both sides of the base film 30 ′ is obtained.
  • the dyeing step can be performed by immersing the entire stretched film 200 in a solution (dye solution) containing a dichroic dye.
  • a solution in which the above dichroic dye is dissolved in a solvent can be used.
  • a solvent for the dyeing solution water is generally used, but an organic solvent compatible with water may be further added.
  • the concentration of the dichroic dye in the dyeing solution is preferably 0.01 to 10% by weight, more preferably 0.02 to 7% by weight, and further preferably 0.025 to 5% by weight. preferable.
  • iodine When iodine is used as the dichroic dye, it is preferable to further add an iodide to the dyeing solution containing iodine because the dyeing efficiency can be further improved.
  • iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Is mentioned.
  • the concentration of iodide in the dyeing solution is preferably 0.01 to 20% by weight. Of the iodides, it is preferable to add potassium iodide.
  • the ratio of iodine to potassium iodide is preferably in the range of 1: 5 to 1: 100, more preferably in the range of 1: 6 to 1:80. Preferably, it is in the range of 1: 7 to 1:70.
  • the temperature of the dyeing solution is preferably in the range of 10 to 60 ° C, more preferably in the range of 20 to 40 ° C.
  • sucked to a polyvinyl alcohol-type resin layer can be orientated favorably.
  • the dyeing step S30 is performed after the laminated film 100 is subjected to at least some stretching treatment. That is, the stretched film 200 obtained by subjecting the stretching process to the target magnification in the stretching process S20 can be used for the dyeing process S30, and after performing the stretching process at a lower ratio than the target in the stretching process S20. In the dyeing step S30, the stretching process can be performed until the total stretching ratio reaches the target ratio.
  • the dyeing step S30 can include a cross-linking treatment step performed subsequent to the dyeing treatment.
  • the crosslinking treatment can be performed by immersing the dyed film in a solution containing a crosslinking agent (crosslinking solution).
  • a crosslinking agent conventionally known substances can be used, and examples thereof include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde.
  • a crosslinking agent may be used individually by 1 type, and may use 2 or more types together.
  • the crosslinking solution can be a solution in which a crosslinking agent is dissolved in a solvent.
  • a solvent for example, water can be used, but an organic solvent compatible with water may be further included.
  • the concentration of the crosslinking agent in the crosslinking solution is preferably in the range of 1 to 20% by weight, more preferably in the range of 6 to 15% by weight.
  • the crosslinking solution can contain iodide.
  • iodide By adding the iodide, the polarization performance in the plane of the polarizer 5 can be made more uniform.
  • iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Is mentioned.
  • the concentration of iodide in the cross-linking solution is preferably 0.05 to 15% by weight, and more preferably 0.5 to 8% by weight.
  • the temperature of the crosslinking solution is preferably in the range of 10 to 90 ° C.
  • the crosslinking treatment can be performed simultaneously with the dyeing treatment by blending a crosslinking agent in the dyeing solution. Further, a stretching process may be performed during the crosslinking process.
  • the specific mode for carrying out the stretching treatment during the crosslinking treatment is as described above. Moreover, you may perform the process immersed in a crosslinking solution 2 or more times using 2 or more types of crosslinking solutions from which a composition differs.
  • the washing process usually includes a water washing process.
  • the water washing treatment can be performed by immersing the film after the dyeing treatment or after the crosslinking treatment in pure water such as ion exchange water or distilled water.
  • the water washing temperature is usually in the range of 3 to 50 ° C., preferably 4 to 20 ° C.
  • the immersion time in water is usually 2 to 300 seconds, preferably 3 to 240 seconds.
  • the washing step may be a combination of a water washing step and a washing step with an iodide solution.
  • any appropriate method such as natural drying, blow drying, and heat drying can be adopted.
  • the drying temperature is usually 20 to 95 ° C.
  • a protective film is applied on the polarizer 5 of the polarizing laminated film 300, that is, on the surface opposite to the base film 30 ′ side of the polarizer 5 via an adhesive layer. It is the process of obtaining the bonding film 400 by combining.
  • the 2nd adhesive bond layer 25 is shown. You may make it bond the 2nd protective film 20 through.
  • the adhesive forming the first adhesive layer 15 and the second adhesive layer 25 is as described above.
  • a protective film is usually bonded to each of the polarizers 5 on both surfaces.
  • these protective films may be the same type of protective film or different types of protective films.
  • the adhesive layer is cured by irradiating ultraviolet rays.
  • the ultraviolet rays to be radiated include light in a wavelength range of 280 to 320 nm (UVB region).
  • a light source for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, a micro lamp A wave excitation mercury lamp, a metal halide lamp, etc. can be used.
  • the ultraviolet curable adhesive forming the first adhesive layer 15 contains the photosensitizer exhibiting the predetermined light absorption characteristics
  • the first protective film 10 side is irradiated with ultraviolet rays from the first protective film 10 side.
  • the adhesive layer 15 can be cured well.
  • the second protective film 20 having an accumulated light amount transmittance of 1 to 50% in the UVB region is used in this step. The same applies to the pasting.
  • the adhesive layer can be cured by irradiating ultraviolet rays from the base film 30 ′ side.
  • a polyester-based resin such as a polyethylene terephthalate resin is used as a base film. May be used.
  • the substrate film 30 ′ since the substrate film 30 ′ also has a very low ultraviolet transmittance, the advantage of using the present invention is particularly great in such a case.
  • the cumulative amount of ultraviolet light to be irradiated can be, for example, 10 to 10,000 mJ / cm 2 , but it is clear that it is advantageous to sufficiently cure the ultraviolet curable adhesive layer if the cumulative amount of light is reduced to a relatively low level. It has become. In view of this point, the integrated light quantity is preferably 500 mJ / cm 2 or less.
  • the amount of heat generated from the light source is reduced by lowering the cumulative amount of ultraviolet light to be irradiated, it is possible to suppress the curling or deterioration of the bonding film 400 (and thus the polarizing plate) due to this heat. Moreover, the damage of the polarizer 5 by ultraviolet irradiation can also be suppressed. That is, when a protective film having a low ultraviolet transmittance is adhered to the polarizer 5, it has been conventionally attempted to increase the integrated amount of ultraviolet rays so that the light reaches the adhesive layer, but at the same time damages the polarizer 5. It is found that the polarizer 5 is more decolored in the wet heat durability test of the polarizing plate when the integrated light quantity is larger. If the integrated light quantity can be reduced, decolorization under such a wet heat durability test can be effectively suppressed.
  • plasma treatment, corona treatment, ultraviolet irradiation treatment, frame (flame) is applied to the surface of the protective film on the polarizer 5 side in order to improve adhesion to the polarizer 5.
  • Surface treatment Easy adhesion treatment
  • plasma treatment, corona treatment or saponification treatment is preferably performed.
  • This step is a step of peeling and removing the base film 30 ′ from the bonding film 400.
  • a polarizing plate with a single-sided protective film similar to that shown in FIG. 1 is obtained, but when the target polarizing plate is a polarizing plate with a single-sided protective film, the first protective film in the first bonding step S40. 10 is bonded.
  • the polarizing laminated film 300 has the polarizer 5 on both surfaces of the base film 30 ′, and a protective film is bonded to both the polarizers 5, a single polarizing laminated film is obtained by the peeling step S 50. Two polarizing plates with a single-side protective film are obtained from the film 300.
  • the method for peeling and removing the base film 30 ′ is not particularly limited, and can be peeled by the same method as the peeling step of a separator (peeling film) performed with a normal pressure-sensitive adhesive polarizing plate.
  • Substrate film 30 ' may peel immediately as it is after 1st bonding process S40, and after 1st bonding process S40, it will wind up in roll shape once, and will peel off, unwinding in the subsequent process. May be.
  • a protective film is further bonded on the polarizer 5 of the polarizing plate with a single-sided protective film, that is, on the surface opposite to the protective film bonded in the first bonding step S40, and is shown in FIG. It is the process of obtaining the polarizing plate 2 with a double-sided protective film.
  • the 1st protective film 10 is bonded in 1st bonding process S40
  • the 2nd protective film 20 is bonded in this process
  • the 2nd protective film 20 is bonded in 1st bonding process S40.
  • the first protective film 10 is bonded in this step.
  • the first protective film 10 is bonded in the first bonding step S40, and the above-described ultraviolet curable adhesive (second adhesive layer 25) containing a photosensitizer exhibiting predetermined light absorption characteristics in the present step.
  • the second protective film 20 having an accumulated light amount transmittance of 1 to 50% in the UVB region is bonded using an adhesive for forming an adhesive layer, ultraviolet irradiation for curing the adhesive layer is usually performed in the first step. 2 Perform from the protective film side.
  • the polarizer was formed from the polyvinyl alcohol-type resin layer coated on the base film, and the method of manufacturing a polarizing plate was explained in full detail, it is not limited to this, It consists of a single-piece
  • the polarizing plate may be produced by bonding the first protective film 10 or the first and second protective films 10 and 20 to the polarizer 5.
  • the polarizer 5 composed of a single (single) film is prepared by, for example, a step of producing a polyvinyl alcohol-based resin film by a known method such as a melt extrusion method or a solvent casting method; a step of uniaxially stretching a polyvinyl alcohol-based resin film; A step of dyeing a resin film with a dichroic dye and adsorbing it; a step of treating a polyvinyl alcohol resin film adsorbed with a dichroic dye with an aqueous boric acid solution; and washing with water after the treatment with an aqueous boric acid solution It can manufacture by the method including a process.
  • Uniaxial stretching can be performed before dyeing of the dichroic dye, simultaneously with dyeing, or after dyeing.
  • this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, you may uniaxially stretch in these several steps.
  • both the first and second protective films 10 and 20 are bonded to produce a polarizing plate with a double-sided protective film
  • these protective films may be sequentially bonded via an adhesive layer, It may be pasted at the same time.
  • the polarizing plate which bonds the 1st and 2nd protective films 10 and 20 with a low ultraviolet-ray transmittance using a UV curable adhesive the merit which uses this invention especially is large.
  • the polarizing plate of the present invention can be applied to a display device.
  • This display device can include a display cell and the polarizing plate according to the present invention, which is disposed on at least one surface thereof.
  • a typical example of the display device is a liquid crystal display device in which the display cell is a liquid crystal cell, but may be another display device such as an organic EL device.
  • the polarizing plate according to the present invention may be disposed on at least one surface of the display cell, but may be disposed on both surfaces.
  • a conventionally known type of liquid crystal cell can be used.
  • a long base film having a three-layer structure in which a resin layer composed of a propylene homopolymer (“Sumitomo Noblen FLX80E4” manufactured by Sumitomo Chemical Co., Ltd., melting point Tm 163 ° C.) is disposed on a multilayer extruder It was produced by the coextrusion molding used.
  • the total thickness of the base film was 90 ⁇ m, and the thickness ratio (FLX80E4 / W151 / FLX80E4) of each layer was 3/4/3.
  • the primer layer forming coating solution is applied to the corona-treated surface using a micro gravure coater at 80 ° C. By drying for 10 minutes, a primer layer having a thickness of 0.2 ⁇ m was formed.
  • the stretched film prepared in the above (4) is about 30 ° C. dyed aqueous solution containing iodine and potassium iodide (0.6 parts by weight of iodine and 10 parts by weight of potassium iodide per 100 parts by weight of water). After the polyvinyl alcohol resin layer was dyed for 180 seconds, the excess dye solution was washed away with pure water at 10 ° C.
  • a first crosslinked aqueous solution of 78 ° C. containing boric acid (containing 9.5 parts by weight of boric acid per 100 parts by weight of water), and then 70 ° C. containing boric acid and potassium iodide.
  • a crosslinking treatment was performed by immersing in a second aqueous crosslinking solution (containing 9.5 parts by weight of boric acid and 4 parts by weight of potassium iodide per 100 parts by weight of water) for 60 seconds. Thereafter, the film was washed with pure water at 10 ° C. for 10 seconds, and finally dried at 40 ° C. for 300 seconds to obtain a polarizing laminated film comprising a base film / primer layer / polarizer.
  • polarizing plate (first bonding step, peeling step, second bonding step) “KR-70T” manufactured by ADEKA Co., Ltd., which is an ultraviolet curable adhesive containing a curable compound that is a cationic polymerizable epoxy compound and a photo cationic polymerization initiator, was prepared.
  • As a photosensitizer 2.0 parts by weight of 1,4-diethoxynaphthalene was mixed with 100 parts by weight of this adhesive to obtain a photosensitizer-containing ultraviolet curable adhesive.
  • FIG. 8 shows the absorption spectrum of 1,4-diethoxynaphthalene measured using an absorptiometer (“UV-2450” manufactured by Shimadzu Corporation). As shown in the figure, 1,4-diethoxynaphthalene has an absorption band in the wavelength range of 280 to 360 nm and does not have an absorption band in the wavelength range exceeding 380 nm.
  • a microgravure coater on the bonding surface of a protective film A (a protective film having a transmittance of 2% of accumulated light in the UVB region made of polyethylene terephthalate) having a thickness of 25 ⁇ m and subjected to corona treatment on the bonding surface. After applying this sensitizer-containing ultraviolet curable adhesive, it was bonded to the polarizer surface of the polarizing laminate film prepared in (5) above using a bonding roll.
  • the adhesive layer is cured by irradiating ultraviolet rays with an integrated light amount of 150 mJ / cm 2 from the base film side using a high-pressure mercury lamp, and protective film A / adhesive layer / polarizer / primer layer / base
  • the bonding film which consists of a layer structure of a material film was obtained (1st bonding process).
  • the thickness of the adhesive layer after curing was about 1 ⁇ m.
  • the base film was peeled and removed from the obtained laminated film (peeling process).
  • the base film was easily peeled off to obtain a polarizing plate with a single-side protective film comprising a protective film A / adhesive layer / polarizer / primer layer.
  • the thickness of the polarizer was 6.7 ⁇ m.
  • a 21 ⁇ m-thick protective film B (a phase difference film having a transmittance of 7% of accumulated light in the UVB region, which is formed by applying a liquid crystal compound on a cyclic polyolefin-based resin film) having a corona treatment on the bonding surface.
  • the adhesive layer is cured by irradiating ultraviolet rays with an integrated light amount of 150 mJ / cm 2 from the protective film B side using a high-pressure mercury lamp, and protective film A / adhesive layer / polarizer / primer layer / adhesion
  • the polarizing plate with a double-sided protective film which consists of a layer structure of an agent layer / protective film B was obtained (2nd bonding process).
  • the thickness of the adhesive layer after curing was about 1 ⁇ m.
  • Examples 2 to 3> A polarizing plate with a double-sided protective film was produced in the same manner as in Example 1 except that the cumulative amount of ultraviolet light when curing the adhesive layers on both sides was as shown in Table 1.
  • a protective film to be bonded in the first bonding step a protective film C (made of a cyclic polyolefin resin and containing an ultraviolet absorber instead of the protective film A is a protective film having a transmittance of 2% in the UVB region. ) was used in the same manner as Example 1 except that a polarizing plate with a double-sided protective film was produced.
  • Example 5 A polarizing plate with a single-sided protective film was produced in the same manner as in Example 1 except that the ultraviolet light was irradiated from the protective film A side in the first bonding step and the second bonding step was not performed.
  • UVB transmittance The type of protective film used in each example and comparative example and the transmittance of the integrated light amount in the UVB region (described as “UVB transmittance” in Table 1), the integrated light amount (irradiation amount) of irradiated ultraviolet rays, and the adhesive Table 1 summarizes the presence or absence of the photosensitizer (1,4-diethoxynaphthalene).
  • the polarizing plates obtained in Examples and Comparative Examples were chip-cut into 4 "sizes and bonded to Corning glass using an adhesive layer.
  • an adhesive was applied to the polarizer surface.
  • the obtained glass-bonded sample was allowed to stand for 48 hours in an environment of a temperature of 80 ° C. and a relative humidity of 90%, and then a similar polarizing plate not subjected to a wet heat durability test was tested for Corning glass. After bonding so as to have a crossed Nicols relationship on the surface opposite to the polarizing plate, this was observed on a backlight in a dark room, and the degree of decolorization was evaluated according to the following criteria. It can be judged that the adhesive layer (both adhesive layers in the polarizing plate with a double-sided protective film) is sufficiently cured, and the results are shown in Table 1.
  • Lv1 Decolorization until the entire polarizer is almost transparent
  • Lv2 Decolorization until the polarizer is in a patchy and nearly transparent state
  • Lv3 The polarizer is partially decolorized
  • Lv4 It is not possible to decolorize, but patchy unevenness can be confirmed.
  • Lv5 No decolorization.

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  • Crystallography & Structural Chemistry (AREA)
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  • Liquid Crystal (AREA)
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US11975500B2 (en) 2019-02-19 2024-05-07 Lg Chem, Ltd. Method for manufacturing polarizing plate

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KR20170073918A (ko) * 2015-12-21 2017-06-29 삼성에스디아이 주식회사 편광판 및 이의 제조방법 및 이를 포함하는 표시 장치
JP2018072533A (ja) * 2016-10-28 2018-05-10 住友化学株式会社 偏光板のセットおよび液晶パネル
KR102063046B1 (ko) * 2017-07-10 2020-01-07 주식회사 엘지화학 원편광판
KR101941650B1 (ko) * 2017-11-24 2019-01-23 주식회사 엘지화학 편광판 및 이를 포함하는 화상 표시 장치
CN111801222B (zh) 2019-01-25 2023-05-12 杉金光电(苏州)有限公司 用于制造偏光板的方法和用于偏光板的粘合剂组合物
JP2020181184A (ja) * 2019-03-14 2020-11-05 住友化学株式会社 偏光板
CN115151848A (zh) * 2020-02-28 2022-10-04 柯尼卡美能达株式会社 偏振片及有机电致发光显示装置

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