JP2018169512A - Optical laminate - Google Patents

Abstract

To provide an optical laminate capable of suppressing a decrease in polarization performance of a polarizer even in a humid heat environment,
An optical laminate having a cured layer of a curable resin composition on at least one surface of a polarizer in which iodine is oriented in a polyvinyl alcohol-based resin, the optical laminate having a temperature of 60 ° C. and a humidity of 90%. An optical laminate, wherein the cured layer has an iodine element content ratio of 0.03 atomic% or less after being placed in the environment of 500 hours.
[Selection] Figure 1

Description

  The present invention relates to an optical laminate.

  Liquid crystal display devices are used in various display devices by taking advantage of low power consumption, operation at low voltage, light weight and thinness. A liquid crystal panel constituting a liquid crystal display device has a configuration in which a pair of polarizing plates are laminated on both surfaces of a liquid crystal cell.

  Conventional polarizing plates have a structure in which protective films are laminated on both sides of a polarizer made of a polyvinyl alcohol resin, and an aqueous adhesive such as a polyvinyl alcohol adhesive is used to laminate the protective film. Widely used. However, when the protective film and the polarizer are laminated via an aqueous adhesive, it is necessary to provide a drying process in order to remove moisture contained in the aqueous adhesive and develop an adhesive force, and the production process is complicated. There was a problem of becoming.

  Therefore, in recent years, it has been proposed to use an active energy ray-curable adhesive instead of the water-based adhesive. Patent Document 1 describes a polarizing plate in which a polarizer and a protective film are laminated via a cured layer of an active energy ray-curable adhesive. The active energy ray-curable adhesive has a (meth) acryloyl group. It is described that it has. Thus, a drying process can be abbreviate | omitted by using an active energy ray hardening-type adhesive agent for lamination | stacking with a polarizer and a protective film.

JP 2013-174922 A

  However, when a cured layer of an active energy ray-curable adhesive is present on the polarizer, there is a problem that the polarization performance of the polarizer is deteriorated in a humid heat environment (for example, a temperature of 60 ° C. and a humidity of 90%).

[1] An optical laminate including a cured layer of a curable resin composition on at least one surface of a polarizer in which iodine is oriented in a polyvinyl alcohol-based resin, the optical laminate having a temperature of 60 ° C. and a relative humidity of 90% An optical laminate, wherein the cured layer has an iodine element content ratio of 0.03 atomic% or less after being placed in the environment of 500 hours.
[2] The optical laminate according to [1], further having a protective film.
[3] The protective film is a cyclic polyolefin resin film, a cellulose resin film, a polycarbonate resin film, a polyolefin resin film, a polyester resin film, an acrylic resin film, a brightness enhancement film, and curing of a curable resin composition. The optical laminate according to [2], which is at least one layer selected from layers.
[4] The optical layered body according to [2] or [3], wherein the moisture permeability of the protective film is 400 g / m ² · day or less.
[5] The optical laminate according to any one of [2] to [4], wherein the protective film has an in-plane retardation, and an in-plane retardation value R ₀ is ₀ to 200 nm at a wavelength of 590 nm.
[6] The optical laminate according to any one of [2] to [5], wherein the protective film has a surface treatment layer on at least one surface.
[7] The optical laminate according to any one of [1] to [6], further having a pressure-sensitive adhesive layer.
[8] The content of the alicyclic epoxy compound contained in the curable resin composition is 5 to 60 parts by weight with respect to 100 parts by weight of the curable resin composition [1] to [7]. The optical laminate according to any one of the above.
[9] A liquid crystal display device in which the optical laminate according to any one of [1] to [8] is disposed in a liquid crystal cell.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that the polarization | polarized-light performance of a polarizer falls also in a humid heat environment.

It is a schematic sectional drawing which shows an example of the optical laminated body of this invention. It is a schematic sectional drawing which shows an example of the optical laminated body of this invention. It is a schematic sectional drawing which shows an example of the optical laminated body of this invention.

  The optical laminate of the present invention will be described with reference to the drawings as appropriate. The optical layered body of the present invention has a polarizer in which iodine is oriented in a polyvinyl alcohol resin, and a cured layer of a curable resin composition (hereinafter sometimes simply referred to as a cured layer).

  As shown in FIG. 1A, the optical laminate 100 has a configuration in which a cured layer 1 is laminated on one surface of a polarizer 2.

  The optical laminate may further have a protective film and an adhesive layer. Examples of the protective film that the optical laminate may have include a cured layer of a curable resin composition and a protective film.

  When a cured layer of a curable resin composition is used as the protective film, in one embodiment, the optical layered body 101 has the cured layer 1 laminated on both surfaces of the polarizer 2 as shown in FIG. It has a configuration. That is, the cured layer of the curable resin composition may be laminated on both sides of the polarizer.

  When a protective film is used as the protective film, the optical laminate may include the protective film only on one side of the polarizer.

  In one embodiment, as shown in FIG. 2 (a), the optical layered body 102 has a cured layer 1 and an adhesive layer 21 laminated in this order on one surface of the polarizer 2, and on the other surface of the polarizer 2. The pressure-sensitive adhesive layer 20 and the protective film 10 have a configuration laminated in this order.

  In one embodiment, as shown in FIG. 2 (b), the optical laminate 103 has a cured layer 1 and a pressure-sensitive adhesive layer 21 laminated in this order on one surface of the polarizer 2, and on the other surface of the polarizer 2. The hardened layer 1 and the protective film 10 have the structure laminated | stacked in this order.

  In one embodiment, as shown in FIG. 2 (c), in the optical laminate 104, the cured layer 1 and the adhesive layer 21 are laminated in this order on one surface of the polarizer 2, and the other surface of the polarizer 2 is laminated. It has the structure by which the adhesive bond layer 30 and the protective film 10 were laminated | stacked in this order.

  In addition, although the adhesive layer 21 can be an adhesive layer for bonding an optical laminated body to a liquid crystal cell, although the said example demonstrated the case where the adhesive layer 21 was laminated | stacked on the hardened layer 1. FIG. Of course, the pressure-sensitive adhesive layer 21 may be laminated on the protective film 10.

  When a protective film is used as the protective film, the optical laminate may be provided with protective films on both sides of the polarizer.

  In one embodiment, as shown in FIG. 3A, the optical laminate 105 includes a cured layer 1, a protective film 11, and an adhesive layer 21 that are laminated in this order on one surface of the polarizer 2. It has the structure by which the adhesive layer 20 and the protective film 10 were laminated | stacked on the other surface.

  In one embodiment, as shown in FIG. 3 (b), the optical laminate 106 has a cured layer 1, a protective film 11 and an adhesive layer 21 laminated in this order on one surface of the polarizer 2. It has the structure by which the hardened layer 1 and the protective film 10 were laminated | stacked on the other surface.

  In one embodiment, as shown in FIG. 3C, the optical layered body 107 includes a cured layer 1, a protective film 11, and an adhesive layer 21 that are laminated in this order on one surface of the polarizer 2. The adhesive layer 30 and the protective film 10 are laminated on the other surface.

  In addition, although the adhesive layer 21 can be an adhesive layer for bonding an optical laminated body to a liquid crystal cell, although the said example demonstrated the case where the adhesive layer 21 was laminated | stacked on the protective film 11. FIG. Of course, the pressure-sensitive adhesive layer 21 may be laminated on the protective film 10.

  Hereinafter, each member which comprises the optical laminated body of this invention is demonstrated.

[Polarizer]
The polarizer used in the present invention is usually a step of uniaxially stretching a polyvinyl alcohol resin film, a step of adsorbing iodine by dyeing the polyvinyl alcohol resin film with iodine, a polyvinyl alcohol resin film on which iodine is adsorbed Is manufactured through a step of treating with an aqueous boric acid solution and a step of washing with water after the treatment with the aqueous boric acid solution.

  As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers with other monomers copolymerizable with vinyl acetate. 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 saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. This polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal and polyvinyl acetal modified with aldehydes can also be used. Moreover, the polymerization degree of polyvinyl alcohol-type resin is about 1,000-10,000 normally, and about 1,500-5,000 are preferable.

What formed the polyvinyl alcohol-type resin into a film is used as a raw film of a polarizer. The method for forming a polyvinyl alcohol-based resin can be formed by a known method. The film thickness of the polyvinyl alcohol-based raw film is preferably about 5 to 35 μm, more preferably 5 to 20 μm, considering that the thickness of the obtained polarizer is 15 μm or less. When the film thickness of the original film is 35 μm or more, it is necessary to increase the draw ratio when producing the polarizer, and the dimensional shrinkage of the obtained polarizer tends to increase.
On the other hand, when the film thickness of the raw film is 5 μm or less, the handling property at the time of stretching is lowered, and there is a tendency that problems such as cutting are likely to occur during production.

  Uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing with iodine, simultaneously with dyeing, or after dyeing. When uniaxial stretching is performed 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.

  In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Further, the uniaxial stretching may be dry stretching in which stretching is performed in the air, or may be wet stretching in which stretching is performed in a state where a solvent is used and the polyvinyl alcohol-based resin film is swollen. The draw ratio is usually about 3 to 8 times.

  As a method of dyeing the polyvinyl alcohol resin film with iodine, for example, a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing iodine and potassium iodide is employed. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water. The content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water.

  The boric acid treatment after dyeing with iodine can usually be performed by immersing the dyed polyvinyl alcohol resin film in a boric acid-containing aqueous solution.

  The amount of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight and preferably 5 to 12 parts by weight per 100 parts by weight of water. The boric acid-containing aqueous solution preferably contains potassium iodide. The amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight and preferably about 5 to 12 parts by weight per 100 parts by weight of water.

  The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. For the water washing treatment, an aqueous potassium iodide solution may be used. After washing with water, a drying process is performed to obtain a polarizer. The drying process can be performed using a hot air dryer or a far infrared heater.

By the drying process, the moisture content of the polarizer is reduced to a practical level. The water content is usually 5 to 20% by weight, preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the flexibility of the polarizer is lost, and the polarizer may be damaged or broken after drying.
On the other hand, if the moisture content exceeds 20% by weight, the thermal stability of the polarizer may be inferior.

  Further, the stretching, dyeing, boric acid treatment, water washing step, and drying step of the polyvinyl alcohol resin film in the production process of the polarizer may be performed in accordance with, for example, the method described in JP2012-159778A. . In the method described in this document, a polyvinyl alcohol resin layer to be a polarizer is formed by coating a polyvinyl alcohol resin on a base film.

  The thickness of the polarizer can usually be 3 μm or more and 30 μm or less, preferably 15 μm or less, and more preferably 10 μm or less. In particular, when the polarizer is 10 μm or less, the amount of iodine contained in the polarizer is small compared to the case where the polarizer is a thick film. Even when the optical layered body includes such a thin film polarizer, it is possible to remarkably suppress a decrease in polarization performance.

[Curing layer of curable resin composition]
The cured layer of the curable resin composition can be formed by applying the curable resin composition to a polarizer or the like and then curing the curable resin composition. Examples of the curable resin composition include an active energy ray curable resin composition and a thermosetting resin composition, and an active energy ray curable resin composition is preferable.
The cured layer can also be a layer (so-called adhesive layer) for bonding the polarizer and the protective film, for example, as shown in FIG. 3 (a). For example, as shown in FIG. 2 (a), It can also be a layer for protecting the polarizer (the above-mentioned protective film).
When the role as an adhesive layer is imparted to the cured layer, the thickness of the cured layer can be 0.01 μm or more and 3 μm or less, and preferably 0.01 μm or more and 2 μm or less. Moreover, when providing the role as a protective film to a hardened layer, the thickness of a hardened layer can be 1 micrometer or more and 10 micrometers or less, and it is preferable to set it as 1 micrometer or more and 7 micrometers or less.

[Active energy ray-curable resin composition]
The active energy ray-curable compound contained in the active energy ray-curable resin composition is preferably a cationic polymerizable compound or a radical polymerizable compound.

(Cationically polymerizable compound)
Examples of the cationically polymerizable compound used in the present embodiment include an epoxy compound or an oxetane compound.

  The content of the cationic polymerizable compound is preferably 10 to 99 parts by weight and preferably 40 to 99 parts by weight with respect to 100 parts by weight of the active energy ray-curable resin composition. More preferred.

  The epoxy compound is one of cationically polymerizable compounds and can be cured by irradiation with active energy rays. When the active energy ray-curable resin composition contains an epoxy compound, and preferably contains an alicyclic epoxy compound, adhesion to the polarizer can be improved.

  Examples of the epoxy compound include an aromatic epoxy compound, a glycidyl ether of a polyol having an alicyclic ring, an aliphatic epoxy compound, and an alicyclic epoxy compound.

  Aromatic epoxy compounds include bisphenol type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F and diglycidyl ether of bisphenol S; phenol novolac epoxy resins, cresol novolac epoxy resins and hydroxybenzaldehyde phenol novolacs Examples thereof include novolak-type epoxy resins such as epoxy resins; glycidyl ethers of tetrahydroxyphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and polyfunctional epoxy resins such as epoxidized polyvinylphenol.

  As the glycidyl ether of a polyol having an alicyclic ring, a nuclear hydrogenated polyhydroxy compound obtained by selectively hydrogenating an aromatic polyol under pressure in the presence of a catalyst under pressure is used as a glycidyl ether. Can be listed. Examples of aromatic polyols include bisphenol type compounds such as bisphenol A, bisphenol F, and bisphenol S; novolac type resins such as phenol novolac resin, cresol novolac resin, hydroxybenzaldehyde phenol novolac resin; tetrahydroxydiphenylmethane, tetrahydroxybenzophenone, A polyfunctional compound such as polyvinylphenol is exemplified.

Glycidyl ether can be obtained by reacting an alicyclic polyol obtained by hydrogenating the aromatic ring of these aromatic polyols with epichlorohydrin.
Among these glycidyl ethers of polyols having an alicyclic ring, hydrogenated bisphenol A diglycidyl ether is preferable.

  Examples of the aliphatic epoxy compound include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. Specifically, 1,4-butanediol diglycidyl ether; 1,6-hexanediol diglycidyl ether; triglycidyl ether of glycerin; triglycidyl ether of trimethylolpropane; diglycidyl ether of polyethylene glycol; Diglycidyl ether of neopentyl glycol; obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to an aliphatic polyhydric alcohol such as ethylene glycol, propylene glycol or glycerin Examples thereof include polyglycidyl ether of polyether polyol.

Moreover, the monofunctional epoxy compound represented by following formula (I) is also mentioned as an aliphatic epoxy compound. R ¹ is an optionally branched alkyl group having 1 to 15 carbon atoms. The alkyl group preferably has 6 or more carbon atoms, more preferably 6 to 10 carbon atoms. Of these, a branched alkyl group is preferred. Examples of the monofunctional epoxy compound represented by the formula (I) include 2-ethylhexyl glycidyl ether.

  An alicyclic epoxy compound refers to a compound having at least one structure in the molecule forming an oxirane ring together with a carbon atom of the alicyclic ring. Here, “a structure in which an oxirane ring is formed together with a carbon atom of an alicyclic ring” means a structure represented by the following formula (II). N in a formula is an integer of 2-5.

A compound in which a group in a form in which one or a plurality of hydrogen atoms in (CH ₂ ) n in formula (II) are removed is bonded to another chemical structure is an alicyclic epoxy compound. One or more hydrogen atoms in (CH ₂ ) n forming the alicyclic ring may be substituted with a linear alkyl group such as a methyl group or an ethyl group.

  As the epoxy compound, an alicyclic epoxy compound is preferable, and an epoxy cyclohexane (n = 4 in the above formula (II)) or epoxy cycloheptane is preferable in that an excellent protective layer can be easily obtained due to adhesion with a polarizer. Epoxy compounds having (with n = 5 in the above formula (II)) are more preferred.

  The content of the epoxy compound is preferably 1 part by weight or more, more preferably 5 parts by weight or more with respect to 100 parts by weight of the active energy ray-curable resin composition, Also good. Moreover, it is preferable that content of an epoxy compound is less than 100 weight part.

  In the active energy ray-curable resin composition, the epoxy compound may be used alone or in combination of two or more.

  Moreover, in addition to said epoxy compound, an active energy ray hardening-type resin composition may contain an oxetane compound as needed. Examples of the oxetane compound include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, 3-ethyl-3- (phenoxymethyl) oxetane, di [( 3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane and the like. Among these, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene and di [(3-ethyl-3-oxetanyl) methyl] ether are mentioned.

  These oxetane compounds can be easily obtained as commercial products. As commercial products, all of them are trade names sold by Toagosei Co., Ltd., “Aron Oxetane (registered trademark) OXT-101”. "Aron oxetane (registered trademark) OXT-121", "Aron oxetane (registered trademark) OXT-221", "Aron oxetane (registered trademark) OXT-221", "Aron oxetane (registered trademark) OXT-212", etc. Can be mentioned.

  The content of the oxetane compound is preferably 0 part by weight or more and 50 parts by weight or less, more preferably 10 parts by weight or more and 40 parts by weight or less with respect to 100 parts by weight of the active energy ray-curable resin composition. .

  In the active energy ray-curable resin composition, the oxetane compound may be used alone or in combination of two or more.

(Radically polymerizable compound)
Furthermore, in addition to the cationic polymerizable compounds such as the epoxy compound and the oxetane compound, a radical polymerizable compound may be included.

  Examples of the radical polymerizable compound include a compound having at least one (meth) acryloyloxy group in the molecule (hereinafter sometimes referred to as “(meth) acrylic compound”), and at least one ( Examples thereof include compounds having a meth) acrylamide group (hereinafter sometimes referred to as “(meth) acrylamide compounds”). The “(meth) acryloyloxy group” means a methacryloyloxy group or an acryloyloxy group, and the (meth) acrylamide group means a methacryloylamide group or an acryloylamide group.

  (Meth) acrylic compounds include (meth) acrylate monomers having at least one (meth) acryloyloxy group in the molecule and (meth) acrylates having at least two (meth) acryloyloxy groups in the molecule. An oligomer etc. are mentioned. These may be used alone or in combination of two or more. When two or more types are used in combination, two or more (meth) acrylate monomers may be used, two or more (meth) acrylate oligomers may be used, and, of course, one or more (meth) acrylate monomers. One or more (meth) acrylate oligomers may be used in combination.

  Examples of (meth) acrylamide compounds include N-substituted (meth) acrylamide compounds. An N-substituted (meth) acrylamide compound is a (meth) acrylamide compound having a substituent at the N-position. A typical example of the substituent is an alkyl group. The N-position substituents may be bonded to each other to form a ring, and —CH 2 — constituting the ring may be substituted with an oxygen atom. Further, a substituent such as an alkyl group or an oxo group (═O) may be bonded to the carbon atom constituting the ring. N-substituted (meth) acrylamides can generally be prepared by reaction of (meth) acrylic acid or its chloride with a primary or secondary amine.

  The content of the radical polymerizable compound is preferably 0 to 70 parts by weight with respect to 100 parts by weight of the active energy ray-curable resin composition.

  In the active energy ray-curable resin composition, the radical polymerizable compound may be used alone or in combination of two or more.

(Cationic polymerization initiator)
When the active energy ray-curable resin composition contains a cationic polymerizable compound such as the oxetane compound or the epoxy compound, it is preferable to further contain a cationic polymerization initiator. The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and initiates a polymerization reaction of the cationic polymerizable compound. Examples of the cationic polymerization initiator include aromatic diazonium salts, onium salts such as aromatic iodonium salts and aromatic sulfonium salts, and iron-arene complexes.

  Examples of the aromatic diazonium salt include benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, and benzenediazonium hexafluoroborate.

  Examples of the aromatic iodonium salt include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, di (4-nonylphenyl) iodonium hexafluorophosphate, and the like.

  Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4′-bis [diphenylsulfonio] diphenyl sulfide bishexa. Fluorophosphate, 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluoroantimonate, 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bis Hexafluorophosphate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di (p-toluyl) sulfoni O] -2-Isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfo Nio-diphenyl sulfide hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenyl sulfide tetrakis (pentafluorophenyl) borate, and the like.

  Examples of the iron-arene complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II) tris ( (Trifluoromethylsulfonyl) methanide and the like.

  These cationic polymerization initiators can be easily obtained from commercial products, for example, “Kayarad (registered trademark) PCI-220” and “Kayarad” sold by Nippon Kayaku Co., Ltd. under the trade names, respectively. (Registered trademark) PCI-620 "," UVI-6990 "sold by Dow Chemical Company," UVACURE (registered trademark) 1590 "sold by Daicel-Cytec Corporation, sold by ADEKA Corporation "Adekaoptomer (registered trademark) SP-150" and "Adekaoptomer (registered trademark) SP-170", "CI-5102", "CIT-1370", "CIT" sold by Nippon Soda Co., Ltd. -1682 "," CIP-1866S "," CIP-2048S "and" CIP-2064S " "DPI-101", "DPI-102", "DPI-103", "DPI-105", "MPI-103", "MPI-105", "BBI-101" sold by Midori Chemical Co., Ltd. "," BBI-102 "," BBI-103 "," BBI-105 "," TPS-101 "," TPS-102 "," TPS-103 "," TPS-105 "," MDS-103 ", "MDS-105", "DTS-102" and "DTS-103", "PI-2074" sold by Rhodia, "CPI-100P" sold by San Apro, etc.

  Among these cationic polymerization initiators, the aromatic sulfonium salt is capable of absorbing light having a wavelength of 300 nm or more, having excellent curability, and obtaining a cured product having good mechanical strength and adhesion. preferable.

  In the active energy ray-curable resin composition, the cationic polymerization initiator may be used singly or in combination of two or more.

(Radical polymerization initiator)
When the active energy ray-curable resin composition contains the above radical polymerizable compound, it is preferable that the active energy ray curable resin composition further contains a radical polymerization initiator. Any radical polymerization initiator may be used as long as it can initiate polymerization of a radical polymerizable compound such as a (meth) acrylic compound by irradiation with active energy rays, and a known one can be used.

  Examples of the radical polymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-methyl-1- [4- ( Acetophenone initiators such as methylthio) phenyl-2-morpholinopropan-1-one and 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzophenone, 4-chlorobenzophenone and 4,4′-diamino Benzophenone initiators such as benzophenone; benzoin ether initiators such as benzoin propyl ether and benzoin ethyl ether; thioxanthone initiators such as 4-isopropylthioxanthone; other xanthone, fluorenone, camphorquinone, Lens aldehyde, such as anthraquinone, and the like.

  Commercially available radical polymerization initiators can be easily obtained. For example, “Irgacure (registered trademark) 184”, “Irgacure (registered trademark) 907” and “Darocur (registered trademark)” manufactured by BASF are available. Trademark) 1173 "," Lucirin (registered trademark) TPO ", and the like.

  In this composition, a radical polymerization initiator may be used individually by 1 type, and may use 2 or more types together.

(Other additives)
The active energy ray-curable resin composition is an antistatic agent, a photosensitizer, a solvent, a leveling agent, an antioxidant, a light stabilizer, and an ultraviolet absorber as long as the effects of the present invention are not impaired in addition to the above-described compounds. An agent or the like may be included.

  Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo compounds, diazo compounds, halogen compounds, and photoreducible dyes.

  Examples of the solvent include aliphatic hydrocarbons such as n-hexane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, propanol, isopropanol and n-butanol; acetone Ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; esters such as methyl acetate, ethyl acetate and butyl acetate; cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve; halogenation such as methylene chloride and chloroform There are hydrocarbons.

  As the leveling agent, various compounds such as silicone-based, fluorine-based, polyether-based, acrylic acid copolymer-based and titanate-based compounds can be used.

  Examples of the antioxidant include primary antioxidants such as phenols and amines, and sulfur secondary antioxidants.

  Examples of the light stabilizer include hindered amine light stabilizers (HALS). Examples of ultraviolet absorbers that may be used in this embodiment include benzophenone-based, benzotriazole-based, and benzoate-based compounds.

  In the optical layered body of the present invention, it is preferable that the iodine content of the cured layer is 0.00 atomic% or more and 0.03 atomic% or less after being placed in an environment of temperature 60 ° C. and humidity 90% for 500 hours. . From the viewpoint of further suppressing the decrease in polarization performance, it is preferably 0.025 atomic% or less, more preferably 0.020 atomic% or less, and may be 0.015 atomic% or less. Further, the iodine element content ratio in the hardened layer may be more than 0.00 atomic%, or may be 0.005 atomic% or more. It is thought that the fall of the polarization performance of a polarizer can be suppressed by making the amount of iodine (or iodine ion) contained in a hardened layer in the above-mentioned range.

  The present inventors estimate the reason as follows, but this estimation does not limit the present invention at all. A compound (for example, an antistatic agent or an alicyclic epoxy compound) contained in the active energy ray-curable resin composition may react with iodine in the polarizer, and iodine in the polarizer may be extracted. As a result, it is considered that the optical performance of the polarizer deteriorates due to the migration of iodine into the cured layer.

  In addition, in this specification, the said iodine element content rate says what was measured by the method as described in the below-mentioned Example. When the optical layered body has cured layers on both sides of the polarizer, the iodine element content ratio of the cured layer is a ratio calculated from the sum of iodine element contents of each cured layer.

  As a method of adjusting the iodine element content in the cured layer to the above range, for example, a method of adjusting the amount of iodine (or iodine ion) that moves to the cured layer over time can be mentioned. Of course, as long as the iodine element content satisfies the above range, an iodide may be added to the curable resin composition.

  Examples of a method for controlling the amount of iodine (or iodine ions) transferred to the cured layer over time include a method of adjusting the content of an alicyclic epoxy compound or an antistatic agent contained in the curable resin composition. It is done. From the viewpoint of suppressing a decrease in polarization performance in a humid heat environment, the content of the alicyclic epoxy compound is preferably 70 parts by weight or less with respect to 100 parts by weight of the solid content of the curable resin composition, and 60% by weight. More preferably, it is 50 parts by weight or less, or 30 parts by weight or less. On the other hand, from the viewpoint of improving the adhesion to the polarizer, the content of the alicyclic epoxy compound is preferably more than 0 parts by weight with respect to 100 parts by weight of the solid content of the curable resin composition. The above may be sufficient and 5 weight part or more may be sufficient. In addition, solid content of curable resin composition represents the sum total of components other than the volatile matter (solvent etc.) in curable resin composition. Further, if the amount of the antistatic agent in the cured layer is increased, the iodine element content ratio in the cured layer can be increased, and if the amount of the antistatic agent is decreased, the iodine element content ratio in the cured layer can be decreased. .

  An iodide may be added to the curable resin composition in advance. Examples of the iodide added to the curable resin composition include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, and iodine. Examples thereof include tin chloride and titanium iodide.

  When forming a cured layer on both surfaces of a polarizer, one cured layer and the other cured layer may be formed from the same curable resin composition, or may be formed from different curable resin compositions. Good.

〔Protective film〕
The protective film may be a resin film formed from a thermoplastic resin, a film having both optical functions such as a retardation film and a brightness enhancement film.

Examples of the thermoplastic resin forming the resin film include polyolefin resins such as chain polyolefin resins (polypropylene resins, etc.) and cyclic polyolefin resins (norbornene resins, etc.); triacetyl cellulose, diacetyl cellulose, etc. Cellulose resin; Polyester resin such as polyethylene terephthalate and polybutylene terephthalate; Polycarbonate resin; Acrylic resin such as (meth) acrylic resin; Polystyrene resin; Polyvinyl chloride resin; Acrylonitrile butadiene styrene Resins; acrylonitrile / styrene resins; polyvinyl acetate resins; polyvinylidene chloride resins; polyamide resins; polyacetal resins; modified polyphenylene ether resins; Polyethersulfone resins; polyarylate resin; polyamideimide resin; can be a film made of polyimide resin or the like.
Each of the above resins may be used alone or in combination.

  A predetermined retardation may be imparted by subjecting the resin film to a stretching treatment. For example, the in-plane retardation value can be set to 0 to 200 nm. Specifically, as the retardation value of the resin film, for example, a film having substantially zero retardation value may be used for an in-plane switching (IPS) mode liquid crystal panel. A retardation value of substantially zero means that the in-plane retardation value at a wavelength of 590 nm is 10 nm or less, the absolute value of the thickness direction retardation value at a wavelength of 590 nm is 10 nm or less, and the thickness direction position at a wavelength of 480 to 750 nm. The absolute value of the phase difference value is 15 nm or less. Further, a phase difference of λ / 4 may be given. In this case, the in-plane retardation value at a wavelength of 590 nm can be set to 100 to 200 nm.

  The brightness enhancement film can be, for example, a reflective polarizer. An example of a reflective polarizer is an anisotropic multiple thin film that transmits linearly polarized light in one vibration direction and reflects linearly polarized light in the other vibration direction, and a specific example thereof is DBEF manufactured by 3M (specialty). (Kaihei 4-268505). Such a reflective polarizing plate is a reflective polarizing plate formed by stretching a multilayer laminate composed of at least two thin films having different refractive index anisotropies. Therefore, such a reflective polarizing plate has at least two thin films, and the stretched at least two thin films have different refractive index anisotropy.

  A surface treatment layer can be provided on at least one surface of the protective film in that it is easy to adjust the moisture permeability of the protective film described later. It is preferable that a surface treatment layer is provided in the surface in the protective film far from the polarizer. Examples of the surface treatment layer include a hard coat layer, an antiglare layer, a light diffusion layer, and an antireflection layer. The thickness of the surface treatment layer can be 1 to 50 μm, and a desired function can be imparted to the protective film while controlling the moisture permeability of the protective film.

The moisture permeability of the protective film disposed on the side opposite to the side to be bonded to the liquid crystal cell is preferably 400 g / m ² · day or less. In view of the results in the Examples section, the moisture permeability is 300 g / m. More preferably, it is m ² · day or less. Although a lower limit is not specifically limited, For example, it can be set to more than 0 g / m < ² > * day. In a humid heat environment, the polarization performance of the polarizer is likely to be degraded due to the influence of moisture. By making the moisture permeability of the protective film in such a range, the degradation of the polarization performance in the humid heat environment should be made smaller. Can do.
In this specification, the moisture permeability means a value measured at a temperature of 40 ° C. and a relative humidity of 90% by a cup method defined in JIS Z 0208.

  When the optical laminate has protective films on both sides of the polarizer, the same protective film may be used, or different protective films may be used. Moreover, the optical laminated body may have an overlapping layer obtained by laminating protective films with an adhesive layer or an adhesive layer described later.

[Adhesive layer]
The adhesive layer is a layer for adhering, for example, a polarizer and a protective film, and examples of the adhesive forming the adhesive layer include an active energy ray curable adhesive and an aqueous adhesive. Moreover, you may use the above-mentioned curable resin composition.

  When using a water-based adhesive, it is preferable to carry out a drying step in order to remove water contained in the water-based adhesive after bonding the polarizer and the protective film. After the drying process, for example, a curing process for curing at a temperature of about 20 to 45 ° C. may be provided.

  When using an active energy ray-curable adhesive, after bonding a polarizer and a protective film, a drying step is performed as necessary, and then the active energy ray-curable adhesive is irradiated by irradiating active energy rays. A curing step for curing is performed. The light source of the active energy ray is not particularly limited, but ultraviolet light having a light emission distribution at a wavelength of 400 nm or less is preferable. Specifically, the low pressure mercury lamp, the medium pressure mercury lamp, the high pressure mercury lamp, the ultrahigh pressure mercury lamp, the chemical lamp, the black light lamp, the micro A wave excitation mercury lamp, a metal halide lamp, etc. can be used.

  In pasting the polarizer and the protective film, saponification treatment, corona treatment, plasma treatment, or the like can be performed on at least one of the pasting surfaces.

(Adhesive layer)
A pressure-sensitive adhesive layer can be used for laminating the polarizer and the protective film and bonding the optical laminate to the liquid crystal cell. Examples of the pressure-sensitive adhesive layer include acrylic pressure-sensitive adhesives, silicone pressure-sensitive adhesives, and rubber-based pressure-sensitive adhesives, and acrylic pressure-sensitive adhesives are preferable in terms of transparency, weather resistance, heat resistance, and workability.

  For the adhesive, if necessary, a tackifier, plasticizer, glass fiber, glass beads, metal powder, other inorganic powders, fillers, pigments, colorants, fillers, antioxidants, UV absorbers Various additives such as an antistatic agent and a silane coupling agent may be appropriately blended.

  The pressure-sensitive adhesive layer is usually formed by applying a pressure-sensitive adhesive solution on a release sheet and drying the pressure-sensitive adhesive solution. For application onto the release sheet, for example, roll coating methods such as reverse coating and gravure coating, spin coating methods, screen coating methods, fountain coating methods, dipping methods, spraying methods and the like can be employed. The release sheet provided with the pressure-sensitive adhesive layer is used by a method of transferring the release sheet.

  The thickness of the adhesive layer arrange | positioned between a polarizer and a protective film (especially brightness enhancement film) can be 3-15 micrometers, for example. The thickness of the adhesive layer for bonding an optical laminated body to a liquid crystal cell can be 5-30 micrometers, for example.

[Liquid Crystal Display]
In the liquid crystal display device of the present invention, the optical laminate is disposed on at least one surface of the liquid crystal cell. The optical layered body of the present invention may be disposed on the viewing side of the liquid crystal cell or on the back side of the liquid crystal cell. According to the liquid crystal display device of the present invention, since the deterioration of the polarizing performance of the polarizer is suppressed even in a humid heat environment, the display quality is excellent.

  Hereinafter, the effects of the present invention will be made clearer by examples. In addition, this invention is not limited to a following example, In the range which does not change the summary, it can change suitably and can implement.

<Measurement of iodine element content>
The protective film (resin film) included in the optical laminate after being subjected to the following wet heat durability test (that is, after being placed in an environment of a temperature of 60 ° C. and a humidity of 90% for 500 hours) was removed by dissolving with a solvent. An element of iodine at each measurement point in the depth direction by X-ray photoelectric spectroscopy (XPS) while exposing the cured layer of the curable resin composition to the surface and sputtering the cured layer with Ar gas cluster ions The ratio (atomic%) was calculated.

The XPS measurement conditions are as follows.

Equipment: K-alpha manufactured by Thermo Fisher Scientific
X-ray source: AlKα X-ray spot size: 400 μm
Neutralizing gun use Ar gas cluster ion energy: 6 keV
Raster size: 1mm x 2mm
Sputtering cycle: 30s
Pass energy: 150 eV
Measurement elements: C1s, O1s, B1s, I3d

  The iodine element content ratio of the cured layer was calculated from the average value of the elemental ratio (atomic%) of iodine at each measurement point from the cured layer surface to the interface between the cured layer and the polarizer. In addition, when the elemental ratio (atomic%) of boron exceeded 0.5 atomic%, it was considered as the interface of a hardening layer and a polarizer, and the measurement point just before that was used for calculation of the iodine element content rate.

<Evaluation of wet heat durability>
The obtained optical laminate was cut into a size of 40 mm in length and 40 mm in width, and the pressure-sensitive adhesive layer of the optical laminate and an alkali-free glass were bonded to obtain a sample. This sample was allowed to stand in an autoclave at a temperature of 50 ° C. and a load of 5 kg for 20 minutes to mature the adhesive state, and then left for 10 hours in an environment at a temperature of 23 ° C. and a relative humidity of 60%. Thereafter, the sample was placed on an ultraviolet-visible spectrophotometer V7100 manufactured by JASCO Corporation, and the UV-visible spectrum of the polarizing plate in the transmission axis direction and the absorption axis direction was measured. The degree of polarization (visibility correction polarization degree) was obtained by calculation according to JIS-Z8729, and this was used as initial optical characteristics.

  The sample was put into a constant temperature and humidity machine manufactured by ESPEC Co., Ltd., and a wet heat durability test was performed in which the sample was left in an environment of 60 ° C. and 90% relative humidity (humid heat environment) for 500 hours. After taking out the sample, it was left for 10 hours in an environment of a temperature of 23 ° C. and a relative humidity of 60%. Then, the degree of polarization was measured in the same manner as the initial optical characteristics were measured.

  Based on the obtained degree of polarization, the degree of polarization degree change was determined by subtracting the degree of polarization before the test from the degree of polarization after the test.

<Evaluation of adhesion: cross hatch test>
An adhesive layer is laminated on a protective film bonded via a cured layer of an active energy ray-curable resin composition in an optical laminate (polarizing plate), and the optical laminate is made into glass via the adhesive layer. Pasted. On the surface of the protective film opposite to the glass surface, 100 squares of 1 mm square were cut with a cutter knife, a cellophane tape was applied thereto, and then peeled off. Adhesion was evaluated by the number of grids. The case where the number of the remaining grids was 100/100 was marked as ◯, and the case where the number was 0 to 99/100 was marked as x.

<Preparation of polarizing plate with single-sided protective film>
A 20 μm-thick polyvinyl alcohol film (average polymerization degree of about 2,400, saponification degree of 99.9 mol% or more) was uniaxially stretched about 5 times by dry stretching, and further kept at 60 ° C. while maintaining the tension state. After being immersed in pure water for 1 minute, it was immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C. for 60 seconds. Then, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C. for 300 seconds. Subsequently, it was washed with pure water at 26 ° C. for 20 seconds and then dried at 65 ° C. to obtain a 7 μm-thick polarizer in which iodine was adsorbed and oriented on a polyvinyl alcohol film.

  Next, on one side of this polarizer, 3 parts of carboxyl group-modified polyvinyl alcohol [trade name “KL-318” obtained from Kuraray Co., Ltd.] is dissolved in 100 parts of water, and a water-soluble epoxy resin is added to the aqueous solution. A water-based adhesive to which 1.5 parts of a certain polyamide epoxy-based additive [trade name “Smiles Resin (registered trademark) 650 (30)” obtained from Taoka Chemical Co., Ltd., aqueous solution with a solid content concentration of 30%] was added. After coating, a 20 μm-thick triacetyl cellulose (TAC) film (trade name “KC2CT” manufactured by Konica Minolta Opto Co., Ltd.) as a protective film is bonded and dried, and consists of a TAC film / aqueous adhesive layer / polarizer. A polarizing plate with a single-sided protective film was obtained.

<Preparation of protective film>
The following protective films were prepared. The moisture permeability was measured at a temperature of 40 ° C. and a relative humidity of 90% by the cup method defined in JIS Z 0208.
Protective film S:
Cyclic polyolefin resin film having a thickness of 25 μm [trade name “ZEONOR FILM (registered trademark) G + 12-025” manufactured by ZEON CORPORATION]. The water vapor transmission rate was 20 g / m ² · day.
Protective film T:
Acrylic resin film [trade name “OXIS (registered trademark)” manufactured by Okura Kogyo Co., Ltd.]. The moisture permeability was 120 g / m ² · day.
Protective film U:
A film having a 15 μm hard coat layer made of an acrylic resin on a TAC film having a thickness of 25 μm. The water vapor transmission rate was 280 g / m ² · day.

<Preparation of active energy ray-curable resin composition>
The components shown below were blended in the weight ratios shown in each Example to prepare an active energy ray-curable resin composition.
[Active energy ray-curable compound]
“Celoxide (registered trademark) 2021P”:
3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, obtained from Daicel Corporation.
“Denacol (registered trademark) EX-211”:
Neopentyl glycol diglycidyl ether, obtained from Nagase ChemteX Corporation.
(Photocationic polymerization initiator)
Triarylsulfonium salt photocationic polymerization initiator:
Obtained from Sun Apro Co., Ltd. in the form of 50% propylene carbonate solution, trade name “CPI-100P”
[Other ingredients]
“SH710”:
Obtained from Toray Dow Corning Co., Ltd., a silicone leveling agent.

<Example 1>
The surface of the protective film S is subjected to corona discharge treatment, and the active energy ray-curable resin composition (Denacol EX-211: 95 parts by weight, Celoxide 2021P: 5 parts by weight, photocationic polymerization initiator: 5 is applied to the corona discharge treatment surface. 0.0 part by weight, leveling agent: 0.20 part by weight) was applied using a bar coater so that the film thickness after curing was about 3 μm. Subsequently, the polarizer surface of the polarizing plate with a single-side protective film was laminated on the active energy ray-curable resin composition layer. Using a UV irradiation device with a belt conveyor (using a “D bulb” manufactured by Fusion UV Systems, Inc.) from the protective film S side, irradiate the UV light so that the integrated light amount from 280 nm to 320 nm is 200 mJ / cm ^2. Thus, the active energy ray-curable resin composition was cured. A pressure-sensitive adhesive layer is laminated on a TAC film bonded with a water-based adhesive, and protective film S / cured layer of active energy ray-curable resin composition / polarizer / water-based adhesive layer / TAC film / pressure-sensitive adhesive layer. The optical laminated body which consists of was produced.
Evaluation of wet heat durability, measurement of iodine element content ratio, and evaluation of adhesion were performed on the obtained optical layered body. The evaluation result of the adhesion was ○.

<Example 2>
As active energy ray-curable resin composition, Denacol EX-211: 85 parts by weight, Celoxide 2021P: 15 parts by weight, Photocationic polymerization initiator: 5.0 parts by weight, and Leveling agent: 0.20 parts by weight An optical laminate was produced in the same manner as in Example 1 except that was used.
Evaluation of wet heat durability, measurement of the iodine element content ratio, and evaluation of adhesion were performed on the obtained optical laminate in the same manner as in Example 1. The evaluation result of the adhesion was ○.

<Example 3>
An optical laminate was produced in the same manner as in Example 1 except that the protective film U was used as the protective film.
Evaluation of wet heat durability, measurement of the iodine element content ratio, and evaluation of adhesion were performed on the obtained optical laminate in the same manner as in Example 1. The evaluation result of the adhesion was ○.

<Example 4>
As active energy ray-curable resin composition, Denacol EX-211: 40 parts by weight, Celoxide 2021P: 60 parts by weight, Photocationic polymerization initiator: 5.0 parts by weight, and Leveling agent: 0.20 parts by weight An optical laminate was produced in the same manner as in Example 1 except that was used.
Evaluation of wet heat durability, measurement of the iodine element content ratio, and evaluation of adhesion were performed on the obtained optical laminate in the same manner as in Example 1. The evaluation result of the adhesion was ○.

<Comparative Example 1>
As active energy ray-curable resin composition, Denacol EX-211: 20 parts by weight, Celoxide 2021P: 80 parts by weight, Photocationic polymerization initiator: 5.0 parts by weight, and Leveling agent: 0.20 parts by weight An optical laminate was prepared in the same manner as in Example 1 except that the protective film T was used as the protective film.
Evaluation of wet heat durability, measurement of the iodine element content ratio, and evaluation of adhesion were performed on the obtained optical laminate in the same manner as in Example 1. The evaluation result of the adhesion was ○.

  The above results are summarized in Table 1. Judgment was made ◯ when the degree of polarization change before and after the wet heat durability test was −0.020% or more, and × when the change in polarization degree before and after the wet heat durability test was less than −0.020%.

  As shown in Table 1, in Examples in which the iodine element content ratio in the cured layer satisfies the scope of the present invention, the degree of decrease in the degree of polarization in a wet heat environment could be reduced.

  According to the present invention, it is useful because it is possible to suppress a decrease in the polarization performance of the polarizer even in a humid heat environment.

DESCRIPTION OF SYMBOLS 1 Cured layer of curable resin composition 2 Polarizer 10, 11 Protective film 20, 21 Adhesive layer 30 Adhesive layer 100, 101, 102, 103, 104, 105, 106, 107 Optical laminate

Claims (9)

An optical laminate comprising a cured layer of a curable resin composition on at least one surface of a polarizer in which iodine is oriented to a polyvinyl alcohol-based resin,
An optical laminate having an iodine element content of the cured layer of 0.03 atomic% or less after the optical laminate is placed in an environment of a temperature of 60 ° C. and a relative humidity of 90% for 500 hours. Furthermore, the optical laminated body of Claim 1 which has a protective film. The protective film is selected from a cyclic polyolefin resin film, a cellulose resin film, a polycarbonate resin film, a polyolefin resin film, a polyester resin film, an acrylic resin film, a brightness enhancement film, and a cured layer of a curable resin composition. The optical laminate according to claim 2, wherein the optical laminate is at least one layer. 4. The optical laminate according to claim ² , wherein the moisture permeability of the protective film is 400 g / m ² · day or less. The optical laminate according to claim 2, wherein the protective film has an in-plane retardation, and an in-plane retardation value R ₀ is ₀ to 200 nm at a wavelength of 590 nm. The optical laminate according to claim 2, wherein the protective film has a surface treatment layer on at least one surface. Furthermore, the optical laminated body in any one of Claims 1-6 which has an adhesive layer. The content ratio of the alicyclic epoxy compound contained in the curable resin composition is 5 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the curable resin composition. Optical laminate. A liquid crystal display device in which the optical laminate according to claim 1 is disposed in a liquid crystal cell.

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