JP2011232504A - Laminate for protection of liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate for protecting a liquid crystal display which is capable of suppressing the deterioration of the visibility of images when viewed from the oblique direction while maintaining the visibility of images when the image plane of the liquid crystal display is viewed from the front direction through a polarization filter such as polarization sunglasses.SOLUTION: The laminate for protecting a liquid display is configured with a polycarbonate resin layer laminated on both sides of an acrylic resin layer. A laminate having an in-plane retardation value of 50 nm or less is preferred. More preferred is a laminate which is integrally laminated by coextrusion of the acrylic resin layer and the polycarbonate resin laminated on both sides of the acrylic resin layer.

Description

  The present invention relates to a laminate for protecting a liquid crystal display.

  As a resin plate for protecting a liquid crystal display, Patent Document 1 describes a polycarbonate resin plate and a resin plate in which an acrylic resin layer is laminated on both surfaces of a polycarbonate resin layer.

JP 2010-85978 A

  A liquid crystal display usually looks at the screen with the naked eye, but a liquid crystal display used outdoors or an in-vehicle liquid crystal display may be viewed through polarized sunglasses. When the polarizing sunglasses are worn and the screen of the liquid crystal display is viewed from the front, the screen may be colored depending on the angle formed by the polarization axis of the emitted light and the transmission axis of the polarizing sunglasses, and the visibility may be lowered. Even when the screen is not colored when viewed from the front direction, the screen may be colored and visibility may be reduced when the screen is viewed from an oblique direction.

  In the 3D liquid crystal display, the screen of the 3D liquid crystal display is viewed by wearing polarized glasses. A resin plate for protecting the liquid crystal display is installed on the front side (viewer side) of the 3D liquid crystal display. When the screen of the three-dimensional liquid crystal display is viewed from the front direction through the resin plate, the screen may be colored depending on the angle formed by the polarization axis of the emitted light and the transmission axis of the polarized glasses, and the visibility may be lowered. Even when the screen is not colored when viewed from the front direction, the screen may be colored and visibility may be reduced when the screen is viewed from an oblique direction.

  The resin plate that protects the liquid crystal display is installed on the front side (viewer side) of the liquid crystal display, through which the liquid crystal display is viewed. According to Patent Document 1, the in-plane retardation value of the resin plate is set within a predetermined range, thereby suppressing deterioration in image visibility when a liquid crystal display screen is viewed from the front direction through a polarizing filter such as polarized sunglasses. Although it is described to do, it does not describe the visibility when the screen is viewed from an oblique direction.

  Therefore, the object of the present invention is to maintain the visibility of the image when viewing the screen of the liquid crystal display from the front direction through a polarizing filter such as polarized sunglasses, and suppress the deterioration of the visibility of the image when viewed from an oblique direction. It is providing the laminated board for liquid crystal display protection which can do.

As a result of intensive studies to solve the above problems, the present inventor has found a solution means having the following configuration, and has completed the present invention.
(1) A laminate for protecting a liquid crystal display, wherein a polycarbonate resin layer is laminated on both sides of an acrylic resin layer.
(2) The laminate for protecting a liquid crystal display according to (1), wherein the in-plane retardation value of the laminate is 50 nm or less.
(3) The laminate for protecting a liquid crystal display according to (1) or (2), wherein the acrylic resin layer and the polycarbonate resin layer laminated on both sides thereof are laminated and integrated by coextrusion. .
(4) The laminate for protecting a liquid crystal display according to any one of (1) to (3), wherein each of the polycarbonate resin layers laminated on both surfaces of the acrylic resin layer has a thickness of 0.1 mm or less.
(5) The laminate for protecting a liquid crystal display according to any one of (1) to (4), wherein a cured film is formed on at least one surface.
(6) The laminate for protecting a liquid crystal display according to any one of (1) to (5), which is used for a touch panel.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that it can suppress that it looks colored when the screen of a liquid crystal display is seen from the diagonal direction through polarizing filters, such as polarized sunglasses. Therefore, according to the laminate for protecting a liquid crystal display of the present invention, the liquid crystal display can be protected while ensuring the visibility of the liquid crystal display.

It is a schematic explanatory drawing which shows the manufacturing method of the laminated board for liquid crystal display protection concerning one Embodiment of this invention.

  The laminate for protecting a liquid crystal display of the present invention (hereinafter sometimes referred to as “laminate”) has a polycarbonate resin layer laminated on both sides of an acrylic resin layer. The laminated plate having such a layer structure is difficult to be colored when the screen of the liquid crystal display is viewed from an oblique direction through a polarizing filter such as polarizing sunglasses.

  As the acrylic resin constituting the acrylic resin layer, a methacrylic resin having excellent transparency and high rigidity is suitable. The methacrylic resin is mainly composed of a methyl methacrylate unit, specifically, a methyl methacrylate resin containing usually 50% by weight or more, preferably 70% by weight or more of a methyl methacrylate unit. It may be a methyl methacrylate homopolymer having 100% by weight of methyl units, or may be a copolymer of methyl methacrylate and another monomer copolymerizable with the methyl methacrylate.

  Examples of the other monomer copolymerizable with methyl methacrylate include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate. Methacrylic acid esters other than methyl methacrylate such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, etc. Acrylic acid esters and the like. Examples of styrene and substituted styrenes include halogenated styrenes such as chlorostyrene and bromostyrene, and alkyl styrenes such as vinyltoluene and α-methylstyrene. Furthermore, unsaturated acids such as methacrylic acid and acrylic acid, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide and the like can also be mentioned. These other monomers that can be copolymerized with methyl methacrylate may be used alone or in combination of two or more.

  The acrylic resin may contain rubber particles. Thereby, the impact resistance of a laminated board can be improved. As the rubber particles, for example, an acrylic multilayer structure polymer, 5 to 80 parts by weight of a rubbery polymer, and 20 to 95 parts by weight of an ethylenically unsaturated monomer such as an acrylic unsaturated monomer is graft-polymerized. And the like, and the like.

  The acrylic multilayer structure polymer should have an elastomer layer of about 20 to 60% by weight, preferably have a hard layer as the outermost layer, and further have a hard layer as the innermost layer. It may be a thing.

  The elastomer layer may be an acrylic polymer layer having a glass transition point (Tg) of less than 25 ° C., specifically, a lower alkyl acrylate, a lower alkyl methacrylate, a lower alkoxyalkyl acrylate, a cyanoethyl acrylate, A polymer obtained by crosslinking one or more monofunctional monomers selected from the group consisting of acrylamide, hydroxy lower alkyl acrylate, hydroxy lower alkyl methacrylate, acrylic acid and methacrylic acid with a polyfunctional monomer such as allyl methacrylate. It is good that it is a layer.

  Examples of the lower alkyl group in the lower alkyl acrylate include linear or branched alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, t-butyl, pentyl and hexyl groups, Examples of the lower alkoxy group in the lower alkoxyalkyl acrylate include linear or branched alkoxy groups having 1 to 6 carbon atoms such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, t-butoxy, pentyloxy, and hexyloxy groups. Can be mentioned. In the case where the monofunctional monomer is used as a main component to form a copolymer, other monofunctional monomers such as styrene and substituted styrene may be copolymerized as a copolymerization component.

  The hard layer may be an acrylic polymer layer having a Tg of 25 ° C. or more, and specifically, an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms is polymerized alone or as a main component. It is good to be. Examples of the alkyl group having 1 to 4 carbon atoms include linear or branched alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, and t-butyl.

  When the main component is an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms, the copolymer component includes other alkyl methacrylates, alkyl acrylates, styrene, substituted styrenes, acrylonitrile, methacrylonitrile, etc. A monofunctional monomer may be used, or a polyfunctional monomer such as allyl methacrylate may be added to form a crosslinked polymer. Examples of the alkyl group in the alkyl methacrylate include the same linear or branched alkyl groups having 1 to 6 carbon atoms as exemplified for the lower alkyl group described above.

  The above-mentioned acrylic multilayer structure polymer is described in, for example, JP-B-55-27576, JP-A-6-80739, JP-A-49-23292, and the like.

  In the graft copolymer obtained by graft polymerization of 20 to 95 parts by weight of an ethylenically unsaturated monomer to 5 to 80 parts by weight of a rubbery polymer, examples of the rubbery polymer include polybutadiene rubber and acrylonitrile / butadiene. Examples include copolymer rubbers, diene rubbers such as styrene / butadiene copolymer rubbers, acrylic rubbers such as polybutyl acrylate, polypropyl acrylate, and poly-2-ethylhexyl acrylate, and ethylene / propylene / non-conjugated diene rubbers. It is done. Examples of the ethylenic monomer used for graft copolymerization with the rubbery polymer include styrene, acrylonitrile, alkyl (meth) acrylate, and the like. These graft copolymers are described, for example, in JP-A Nos. 55-147514 and 47-9740.

  The usage-amount of a rubber particle is 3-150 weight part normally with respect to 100 weight part of acrylic resins, Preferably it is 4-50 weight part, More preferably, it is 5-30 weight part. The greater the amount of rubber particles used, the better the impact resistance of the laminate, and it tends to be harder to break even when pressed, but if too much rubber particles are used, the surface hardness of the laminate decreases. It is not preferable.

  On the other hand, examples of the polycarbonate resin constituting the polycarbonate resin layer include those obtained by reacting, for example, a dihydric phenol and a carbonylating agent by an interfacial polycondensation method, a melt transesterification method, or the like. Examples thereof include those obtained by polymerizing by a transesterification method and the like, and those obtained by polymerizing a cyclic carbonate compound by a ring-opening polymerization method.

  Examples of the dihydric phenol include hydroquinone, resorcinol, 4,4′-dihydroxydiphenyl, bis (4-hydroxyphenyl) methane, bis {(4-hydroxy-3,5-dimethyl) phenyl} methane, 1,1- Bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 2,2-bis (4-hydroxyphenyl) propane (commonly called bisphenol A), 2,2-bis { (4-hydroxy-3-methyl) phenyl} propane, 2,2-bis {(4-hydroxy-3,5-dimethyl) phenyl} propane, 2,2-bis {(4-hydroxy-3,5-dibromo) ) Phenyl} propane, 2,2-bis {(3-isopropyl-4-hydroxy) phenyl} propane, 2,2-bis {( -Hydroxy-3-phenyl) phenyl} propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) -3-methylbutane, 2,2-bis (4-hydroxyphenyl) ) -3,3-dimethylbutane, 2,4-bis (4-hydroxyphenyl) -2-methylbutane, 2,2-bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxyphenyl)- 4-methylpentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -4-isopropylcyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3 , 5-trimethylcyclohexane, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis {(4-hydroxy -3-methyl) phenyl} fluorene, α, α′-bis (4-hydroxyphenyl) -o-diisopropylbenzene, α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene, α, α′- Bis (4-hydroxyphenyl) -p-diisopropylbenzene, 1,3-bis (4-hydroxyphenyl) -5,7-dimethyladamantane, 4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxydiphenylsulfoxide, 4,4′-dihydroxydiphenyl sulfide, 4,4′-dihydroxydiphenyl ketone, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl ester, and the like, and two or more of them are used as necessary. You can also.

  Among them, bisphenol A, 2,2-bis {(4-hydroxy-3-methyl) phenyl} propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) -3 -Methylbutane, 2,2-bis (4-hydroxyphenyl) -3,3-dimethylbutane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 1,1-bis (4-hydroxyphenyl) It is preferable to use a dihydric phenol selected from −3,3,5-trimethylcyclohexane and α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene alone or in combination of two or more. Of 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane and bisphenol A, one or more dihydric phenols selected from 2,2-bis {(4-hydroxy-3-methyl) phenyl} propane and α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene Use in combination is preferred.

  Examples of the carbonylating agent include carbonyl halides such as phosgene; carbonate esters such as diphenyl carbonate;

  The polycarbonate resin layer preferably contains an acrylic resin in order to improve adhesion to the acrylic resin layer. Specifically, the polycarbonate resin layer is preferably composed of a polycarbonate resin composition containing 0.01 to 1 part by weight of an acrylic resin with respect to 100 parts by weight of the polycarbonate resin. As said acrylic resin, the same acrylic resin as what was used for the above-mentioned acrylic resin layer is employable, and the thing of a low molecular weight is used preferably. The preferred molecular weight range is 1,000 to 100,000. If the molecular weight is too low, the acrylic resin volatilizes during extrusion molding. If the molecular weight is too high, the acrylic resin may cause phase separation with the polycarbonate resin, which may reduce light transmittance.

  The compositions of the polycarbonate resin layers on both sides may be the same as or different from each other. In addition, the polycarbonate resin layer and the acrylic resin layer may each include one or more additives such as a light stabilizer, an ultraviolet absorber, an antioxidant, a flame retardant, and an antistatic agent, as necessary. May be.

  The laminate is preferably manufactured by laminating and integrating an acrylic resin layer and a polycarbonate resin layer laminated on both sides thereof by coextrusion molding. In this coextrusion molding, the material of the acrylic resin layer and the material of the polycarbonate resin layer are melt-kneaded using a two or three uniaxial or biaxial extruder, respectively, and then fed block die or multi-manifold die. Etc. can be carried out by laminating them. What is necessary is just to cool and solidify the fusion | melting lamination | stacking resin body by which the lamination | stacking integration was carried out, for example using a roll unit etc. The laminated board manufactured by coextrusion molding is preferable at the point which is easy to perform secondary shaping | molding compared with the laminated board manufactured by the bonding using an adhesive or an adhesive agent.

  Hereinafter, an embodiment for producing a laminate by coextrusion will be described in detail with reference to FIG. As shown in the figure, first, the material of the acrylic resin layer and the material of the polycarbonate resin layer are heated and melted and kneaded by separate extruders 1 and 2, respectively, and fed to the feed block, respectively, and fused and laminated. After that, it is extruded from the die 3 and laminated and integrated.

  Next, the sheet-shaped or film-shaped molten resin 4 extruded from the die 3 is sandwiched between the first cooling roll 5 and the second cooling roll 6 that are arranged to face each other in a substantially horizontal direction, and is molded and cooled. By adjusting the thickness of the molten resin 4, the distance between the first and second cooling rolls 5 and 6, the peripheral speed, etc., the thickness of the resulting laminate can be adjusted.

  At least one of the first and second cooling rolls 5 and 6 is connected to a rotation driving means such as a motor, and both rolls are configured to rotate at a predetermined peripheral speed. Among the two rolls, the second cooling roll 6 is a winding roll around which a sheet-like or film-like laminate is sandwiched between the two rolls.

  Examples of the first and second cooling rolls 5 and 6 include a metal roll having rigidity and a metal elastic roll having elasticity. Examples of the metal roll include a drilled roll and a spiral roll. The metal elastic roll includes, for example, a shaft roll and a cylindrical metal thin film that is disposed so as to cover the outer peripheral surface of the shaft roll and is in contact with the molten resin 4, and between the shaft roll and the metal thin film. And a material in which a temperature-controlled fluid such as water or oil is enclosed, or a metal belt wrapped around the surface of a rubber roll.

  The 1st, 2nd cooling rolls 5 and 6 may be comprised by 1 type chosen from a metal roll and a metal elastic roll, and may be comprised combining a metal roll and a metal elastic roll.

  When a metal roll and a metal elastic roll are combined, a laminated sheet with reduced strength, anisotropy of heat shrinkage, and the like can be obtained. That is, when the molten resin 4 is sandwiched between the metal roll and the metal elastic roll, the metal elastic roll is elastically deformed into a concave shape along the outer peripheral surface of the metal roll via the molten resin 4, and the metal elastic roll and the metal roll Is contacted through the molten resin 4 with a predetermined contact length. As a result, the metal roll and the metal elastic roll come into pressure contact with the molten resin 4 by surface contact, and the molten resin 4 sandwiched between these rolls is formed into a film while being uniformly pressed into a planar shape. . As a result, it is possible to obtain a laminated sheet with reduced distortion during film formation and reduced strength and thermal shrinkage anisotropy.

  Moreover, when combining a metal roll and a metal elastic roll, it is preferable to use the metal elastic roll as the first cooling roll 5 and the metal roll as the second cooling roll 6. Thereby, the effect acquired by combining a metal roll and a metal elastic roll can be heightened.

  The sheet-like or film-like laminate after being sandwiched between the first and second cooling rolls 5 and 6 is wound around the second cooling roll 6 and then cooled on the transport roll by a take-off roll (not shown). As a result, the laminate is obtained.

  The resulting laminate is usually in the form of a sheet or film, and the thickness is usually 0.1 to 3 mm, preferably 0.1 to 2 mm, and more preferably 0.1 to 1.5 mm. In this laminated board, the thickness of each polycarbonate resin layer laminated on both sides of the acrylic resin layer is preferably 0.1 mm or less, and more preferably 0.01 to 0.1 mm. If the polycarbonate resin layer is too thick, the liquid crystal display screen may be colored when viewed from an oblique direction through a polarizing filter such as polarized sunglasses. Also, the retardation value tends to be high, and therefore there is a risk of coloring. The thicknesses of the polycarbonate resin layers on both sides may be the same as or different from each other. The thickness of the acrylic resin layer is preferably 70 to 99% of the thickness of the entire laminate.

  The obtained resin plate preferably has an in-plane retardation value of 50 nm or less, and more preferably 5 to 50 nm. If the in-plane retardation value is too large, the screen may appear colored when the screen of the liquid crystal display is viewed from an oblique direction through a polarizing filter such as polarized sunglasses. On the other hand, if the in-plane retardation value is too small, when the screen of the liquid crystal display is viewed from the front direction through a polarizing filter such as polarized sunglasses, the screen may become dark and visibility may deteriorate.

  On the other hand, in order to improve the scratch resistance, the laminated board preferably forms a cured film on at least one side. In addition, when forming a cured film on both surfaces of a laminated board, the composition and thickness of a cured film of both surfaces may mutually be the same, and may differ.

  The cured film is formed by curing a curable coating composition. The curable coating composition contains a curable compound that provides scratch resistance as an essential component, and contains, for example, a curing catalyst, conductive particles, a solvent, a leveling agent, a stabilizer, an antioxidant, and the like as necessary. Is.

  Examples of the curable compound include acrylate compounds, urethane acrylate compounds, epoxy acrylate compounds, carboxyl group-modified epoxy acrylate compounds, polyester acrylate compounds, copolymer acrylate compounds, alicyclic epoxy resins, glycidyl ether epoxy resins, vinyl ether compounds, Examples include oxetane compounds. Among these, from the viewpoint of scratch resistance of the cured film, radical polymerization curable compounds such as polyfunctional acrylate compounds, polyfunctional urethane acrylate compounds, and polyfunctional epoxy acrylate compounds, and thermal polymerization systems such as alkoxysilanes and alkylalkoxysilanes. These curable compounds are preferably used. These curable compounds are preferably cured by irradiating energy beams such as electron beam, radiation, and ultraviolet rays, or cured by heating. These curable compounds may be used alone or in combination of a plurality of compounds.

  Particularly preferred curable compounds are those having at least three (meth) acryloyloxy groups in the molecule. Here, the (meth) acryloyloxy group means an acryloyloxy group or a methacryloyloxy group. In addition, in this specification, “(meth)” when referred to as (meth) acrylate, (meth) acrylic acid, etc. Is the meaning.

  Examples of the compound having at least three (meth) acryloyloxy groups in the molecule include trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, glycerin tri (meth) acrylate, pentaglycerol tri ( (Meth) acrylate, pentaerythritol tri- or tetra- (meth) acrylate, dipentaerythritol tri-, tetra-, penta- or hexa- (meth) acrylate, tripentaerythritol tetra-, penta-, hexa- or hepta- ( A poly (meth) acrylate of a polyhydric alcohol having a valence of 3 or more, such as (meth) acrylate; a compound having at least two isocyanato groups in the molecule, and a (meth) acrylate having a hydroxyl group with respect to the isocyanato group Urethane (meth) acrylate obtained by reacting at a ratio of hydroxyl groups equal to or higher than moles, and having 3 or more (meth) acryloyloxy groups in the molecule [for example, diisocyanate and pentaerythritol tri (meth) acrylate And the like, trifunctional (urethane) methacrylate (tri) (tri) (2-hydroxyethyl) isocyanuric acid tri (meth) acrylate and the like. In addition, although the monomer was illustrated here, you may use these monomers as it is, for example, you may use what was in the form of oligomers, such as a dimer and a trimer. Moreover, you may use a monomer and an oligomer together. These (meth) acrylate compounds may be used alone or in combination of two or more.

  Commercially available compounds can be used as the compound having at least three (meth) acryloyloxy groups in the molecule. Specific examples thereof include, for example, “NK HARD M101” manufactured by Shin-Nakamura Chemical Co., Ltd. (Urethane acrylate), "NK ester A-TMM-3L" (pentaerythritol triacrylate), "NK ester A-TMMT" (pentaerythritol tetraacrylate), "NK ester A-9530" (dipentaerythritol pentaacrylate) And “NK Ester A-DPH” (dipentaerythritol hexaacrylate), “KAYARAD DPCA” (dipentaerythritol hexaacrylate) manufactured by Nippon Kayaku Co., Ltd., “Nopcocure 200” series manufactured by San Nopco, Dainippon Inn Chemical Industry Co., Ltd. of the (stock) "Uni-Dick" series, and the like.

  In addition, when using the said compound which has at least 3 (meth) acryloyloxy group in a molecule | numerator as a sclerosing | hardenable compound, as another sclerosing | hardenable compound as needed, for example, ethylene glycol di (meth) acrylate, In combination with a compound having two (meth) acryloyloxy groups in the molecule, such as diethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate However, the amount used is preferably up to 20 parts by weight per 100 parts by weight of the compound having at least three (meth) acryloyloxy groups in the molecule.

  When the curable coating composition is cured with ultraviolet rays, a photopolymerization initiator is preferably used as a curing catalyst. Examples of the photopolymerization initiator include benzyl, benzophenone and derivatives thereof, thioxanthones, benzyldimethyl ketals, α-hydroxyalkylphenones, hydroxyketones, aminoalkylphenones, acylphosphine oxides, and the like. Depending on the situation, two or more of them can be used. The usage-amount of a photoinitiator is 0.1-5 weight part normally with respect to 100 weight part of sclerosing | hardenable compounds.

  Commercially available photopolymerization initiators can be used. Specific examples thereof include, for example, “IRGACURE 651”, “IRGACURE 184”, “IRGACURE 500” manufactured by Ciba Specialty Chemicals, Inc., “IRGACURE 1000”, “IRGACURE 2959”, “DAROCUR 1173”, “IRGACURE 907”, “IRGACURE 369”, “IRGACURE 1700”, “IRGACURE 1800”, “IRGACURE 819”, “IRGACURE GACURE 784” Series and DAROCUR series, both “KAYACURE ITX”, “KAYACURE DETX-S”, “K” manufactured by Nippon Kayaku Co., Ltd. YACURE BP-100 "," KAYACUREBMS "," KAYACURE 2-EAQ "such as KAYACURE (Kayacure) series, and the like.

  By containing conductive particles in the curable coating composition, antistatic properties can be imparted to the cured coating. Examples of the conductive particles include inorganic particles such as antimony-tin composite oxide, tin-containing tin oxide, antimony oxide, antimony-zinc composite oxide, titanium oxide, and indium-tin composite oxide (ITO). Preferably used.

  The particle diameter of the conductive particles is usually 0.5 μm or less, and is preferably 0.001 μm or more in terms of the average particle diameter from the viewpoint of antistatic properties and transparency of the cured film. It is preferably 1 μm or less, and more preferably 0.05 μm or less. The smaller the average particle diameter of the conductive particles, the lower the haze of the laminate and the higher the transparency.

  The usage-amount of the said electroconductive particle is 2-50 weight part normally with respect to 100 weight part of curable compounds, Preferably it is 3-20 weight part. As the amount of the conductive particles used increases, the antistatic property of the cured coating tends to improve. However, when the amount of the conductive particles used excessively decreases the transparency of the cured coating, it is not preferable.

  The conductive particles can be produced by, for example, a gas phase decomposition method, a plasma evaporation method, an alkoxide decomposition method, a coprecipitation method, a hydrothermal method, or the like. The surface of the conductive particles may be surface-treated with, for example, a nonionic surfactant, a cationic surfactant, an anionic surfactant, a silicon coupling agent, an aluminum coupling agent, or the like.

  The curable coating composition may contain a solvent for the purpose of adjusting the viscosity thereof. In particular, when conductive particles are contained, the solvent is preferably contained for dispersion. When preparing a curable coating composition containing conductive particles and a solvent, for example, the conductive particles and the solvent are mixed, the conductive particles are dispersed in the solvent, and then the dispersion is curable. You may mix with a compound, and after mixing a sclerosing | hardenable compound and a solvent, you may disperse | distribute electroconductive particle in this liquid mixture.

  The solvent should be one that can dissolve the curable compound and can easily volatilize after coating, and can disperse it when conductive particles are used as a paint component. It is good to be. Examples of such a solvent include alcohols such as diacetone alcohol, methanol, ethanol, isopropyl alcohol, isobutyl alcohol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 1-methoxy-2-propanol, and acetone. , Ketones such as methyl ethyl ketone, methyl isobutyl ketone and diacetone alcohol, aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, and water. What is necessary is just to adjust the usage-amount of the said solvent suitably according to the property etc. of a curable compound.

  When a leveling agent is contained in the curable coating composition, silicone oil is preferably used. Examples thereof include dimethyl silicone oil, phenylmethyl silicone oil, alkyl / aralkyl-modified silicone oil, fluorosilicone oil, and polyether. Modified silicone oil, fatty acid ester modified silicone oil, methyl hydrogen silicone oil, silanol group containing silicone oil, alkoxy group containing silicone oil, phenol group containing silicone oil, methacrylic modified silicone oil, amino modified silicone oil, carboxylic acid modified silicone oil, carb Nord modified silicone oil, epoxy modified silicone oil, mercapto modified silicone oil, fluorine modified silicone oil, polyether modified Recone oil, and the like. These leveling agents may be used alone or in combination of two or more. The usage-amount of the said leveling agent is 0.01-5 weight part normally with respect to 100 weight part of sclerosing | hardenable compounds.

  As the leveling agent, a commercially available product can be used, and specific examples include, for example, “SH200-100cs”, “SH28PA”, “SH29PA”, “SH30PA” manufactured by Toray Dow Corning Silicone Co., Ltd. , “ST83PA”, “ST80PA”, “ST97PA” and “ST86PA”, all of which are “BYK-302”, “BYK-307”, “BYK-320” and “BYK-” manufactured by Big Chemie Japan Co., Ltd. 330 "and the like.

  The curable coating composition thus obtained can be applied to the laminate to form a curable coating film, and then cured to form a cured film. The curable coating composition may be applied by a coating method such as a bar coating method, a micro gravure coating method, a roll coating method, a flow coating method, a dip coating method, a spin coating method, a die coating method, or a spray coating method. The curable coating film may be cured by irradiation with energy rays, heating, or the like depending on the type of the curable coating composition.

  Examples of energy rays in the case of curing by irradiation with energy rays include ultraviolet rays, electron beams, and radiation, and conditions such as intensity and irradiation time are appropriately selected according to the type of curable coating composition. . In addition, in the case of curing by heating, conditions such as temperature and time are appropriately selected according to the type of the curable coating composition, but the heating temperature is generally set so that the laminate does not deform. Is preferably 100 ° C. or lower. When the curable coating composition contains a solvent, after application, the solvent may be volatilized and then the curable coating film may be cured, or the solvent may be volatilized and the curable coating film may be cured simultaneously. Also good.

  The thickness of the cured film is preferably 0.5 to 50 μm, more preferably 1 to 20 μm. As the thickness of the cured film is smaller, cracks tend not to occur easily. However, if the thickness is too small, the scratch resistance becomes insufficient, which is not preferable.

  If necessary, the laminate may be subjected to antireflection treatment on the surface by a coating method, a sputtering method, a vacuum deposition method, or the like. Further, an antireflection sheet prepared separately may be bonded to one or both sides of the laminated plate to give an antireflection effect.

  The laminate of the present invention thus obtained is preferably used for protecting a liquid crystal display, and more preferably used for protecting a three-dimensional liquid crystal display. In addition, display applications to be protected include, for example, a display window of a portable information terminal such as a TV or computer monitor, a mobile phone, a personal handy-phone system (PHS), or a PDA (Personal Digital Assistant), a digital camera, or a handy device. Type video camera viewfinder, portable game console display window, car navigation system and portable information terminal, industrial machine operation panel, touch panel for portable game console, etc. Preferably used.

  In order to produce a protective plate for a liquid crystal display from the laminated plate of the present invention, first, if necessary, processing such as printing, drilling, etc. may be performed, and cutting processing may be performed to a required size. Then, if it is set on a liquid crystal display, the liquid crystal display can be effectively protected. In that case, when the cured film is formed only on one side of the laminate, the side on which the cured film is formed is the front side (viewer side), and the side on which the cured film is not formed is the back side (liquid crystal display side). It is better to set as follows.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

The structure of the extrusion apparatus used in the following examples and comparative examples is as follows.
Extruder 1: An extruder with a screw diameter of 65 mm, a single screw, and a vent (manufactured by Toshiba Machine Co., Ltd.) was used.
Extruder 2: An extruder with a screw diameter of 45 mm, a single screw, and a vent (manufactured by Hitachi Zosen Corporation) was used.
Feed block: A two-type three-layer distribution type feed block (manufactured by Hitachi Zosen Corporation) was used.
-Die 3: A T-die (manufactured by Hitachi Zosen Corporation) having a lip width of 1400 mm and a lip interval of 1 mm was used.
-1st, 2nd cooling rolls 5 and 6: The horizontal type, the surface length of 1400 mm, and the cooling roll of diameter 300mm (phi) were used.

  More specifically, the first and second cooling rolls 5 and 6 are metal elastic rolls. As the metal elastic roll, a metal thin film is disposed so as to cover the outer peripheral surface of the shaft roll, and a fluid is sealed between the shaft roll and the metal thin film.

The shaft roll, metal thin film and fluid are as follows.
Shaft roll: Stainless steel metal thin film: Stainless steel mirror surface metal sleeve fluid of 2 mm thickness Fluid: Oil. By controlling the temperature of this oil, the temperature of the metal elastic roll can be controlled. More specifically, the oil was heated and cooled by ON / OFF control of a temperature controller so that the temperature could be controlled and circulated between the shaft roll and the metal thin film.

  As the second cooling roll 6, a highly rigid metal roll was used. The metal roll is a stainless steel spiral roll having a mirror surface.

The resins used in the examples and comparative examples are the following two types.
Resin 1: A polycarbonate resin “Caliver 301-10” manufactured by Sumitomo Dow Co., Ltd. having a heat distortion temperature (Th) of 140 ° C. was used.
Resin 2: A methacrylic resin “SUMIPEX EX” manufactured by Sumitomo Chemical Co., Ltd. having a heat distortion temperature (Th) of 100 ° C. was used.

[Examples 1 to 9 and Comparative Example 1]
<Production of laminated plate>
First, the extruders 1 and 2, the die 3, the first and second cooling rolls 5 and 6 were arranged as shown in FIG. 1, and the feed block was arranged at a predetermined position. Next, the resin of the type shown in Table 1 as the resin layer A was melt-kneaded by the extruder 1, and the resin of the type shown in Table 1 as the resin layer B was melt-kneaded by the extruder 2, and each was supplied to the feed block. . Co-extrusion molding was performed so that the resin layer A supplied from the extruder 1 to the feed block became an intermediate layer, and the resin layer B supplied from the extruder 2 to the feed block became both surface layers.

  Next, the film-like molten resin 4 extruded from the die 3 is sandwiched between the first cooling roll 5 and the second cooling roll 6 that are arranged to face each other, and is molded and cooled, and the resin layer B is formed on both surfaces of the resin layer A. A laminated sheet having a three-layer structure having the thickness shown in Table 1 was obtained. The composition and thickness of the resin layers B on both sides of each obtained laminate are the same.

  In addition, the surface temperature of the 1st cooling roll 5 was 120 degreeC, and the surface temperature of the 2nd cooling roll 6 was 130 degreeC. These temperatures are values obtained by actually measuring the surface temperature of each cooling roll. Further, “thickness” in the extruders 1 and 2 in Table 1 indicates the thickness of each of the resin layers A and B, and “total thickness” indicates the total thickness of the obtained laminate.

<Formation of cured film>
Among the obtained laminates, cured laminates were formed on both sides of the laminates according to Examples 8 and 9. First, as a monomer, 50 parts of dipentaerythritol hexaacrylate, 50 parts of pentaerythritol tetraacrylate, 4.5 parts of IRGACURE184 manufactured by Ciba Specialty Chemicals as an initiator, 1.5 parts of IRGACURE907, BYK-307 manufactured by BYK Japan as a leveling agent was mixed with 125 parts of isobutyl alcohol and 125 parts of 1-methoxy-2-propanol at a ratio of 0.1 part to obtain a curable paint. .

Next, this curable coating was applied to both surfaces of the laminates according to Examples 8 and 9 with a No. 16 bar coater, and cured by irradiating 0.5 J / cm ² of ultraviolet rays using a 120 W high-pressure mercury lamp. Thus, a cured film having a thickness of about 3.5 μm was formed on both sides.

<Evaluation>
About each obtained laminated board, the coloring and retardation value when it saw from the diagonal direction were evaluated. Each evaluation method is shown below, and the results are also shown in Table 1.

(Coloring when viewed from an oblique direction)
First, of the both sides of the laminate obtained above, one side arbitrarily selected and the surface of the first polarizing plate were overlapped. Next, a second polarizing plate was superimposed on the other surface of the laminated plate opposite to the one surface so that the first polarizing plate and the polarization axis were orthogonal to each other. As the first and second polarizing plates, “Sumikaran SG” manufactured by Sumitomo Chemical Co., Ltd. was used.

Then, while illuminating the surface of the second polarizing plate with light of a three-wavelength type fluorescent lamp (“Lupica Ace” manufactured by Mitsubishi Electric Osram Co., Ltd.), the second polarizing plate is obliquely inclined from about 45 degrees above the second polarizing plate. When the surface of the other surface of the laminate was viewed through the surface, it was visually observed whether or not the surface of the other surface of the laminate appeared to be colored. The following criteria were used.
○: Colored and invisible.
X: It looks colored.

(Retardation value)
The retardation value at 590 nm was measured using an automatic birefringence meter “KOBRA-CCD / X” manufactured by Oji Scientific Instruments.

[Comparative Example 2]
The types of resins shown in Table 1 were melted and kneaded in the extruder 1 and fed in the order of the feed block and the die 3. Then, the molten resin 4 extruded from the die 3 is sandwiched between the first cooling roll 5 and the second cooling roll 6 that are arranged to face each other, and then molded and cooled, and a resin having a single-layer configuration having the thickness shown in Table 1 I got a plate.

  About the obtained resin board, it carried out similarly to the said Examples 1-9, and the coloring and retardation value when it looked from the diagonal direction were evaluated. The results are shown in Table 1.

  As is clear from Table 1, Examples 1 to 9, in which the resin layer B made of polycarbonate resin is laminated on both surfaces of the resin layer A made of methacrylic resin, when the surface is viewed obliquely through the polarizing plate It can be seen that the appearance of coloring can be suppressed. Moreover, since the retardation value is also 50 nm or less, it turns out that visibility is fully ensured. In addition, when Examples 1-9 looked at the surface from the front direction through the polarizing plate, the visibility was not lowered.

  On the other hand, Comparative Example 1 in which a resin layer B made of methacrylic resin is laminated on both surfaces of a resin layer A made of polycarbonate resin, and Comparative Example 2 having a single layer structure made of a polycarbonate resin layer both have a polarizing plate interposed therebetween. The surface looked colored when viewed from an oblique direction.

1, 2 Extruder 3 Die 4 Molten resin 5 First cooling roll 6 Second cooling roll

Claims (6)

  A laminate for protecting a liquid crystal display, wherein a polycarbonate resin layer is laminated on both sides of an acrylic resin layer.   The laminated plate for protecting a liquid crystal display according to claim 1, wherein an in-plane retardation value of the laminated plate is 50 nm or less.   The laminate for protecting a liquid crystal display according to claim 1 or 2, wherein the acrylic resin layer and the polycarbonate resin layer laminated on both surfaces thereof are laminated and integrated by coextrusion.   The laminate for protecting a liquid crystal display according to any one of claims 1 to 3, wherein each of the polycarbonate resin layers laminated on both surfaces of the acrylic resin layer has a thickness of 0.1 mm or less.   The laminated plate for protecting a liquid crystal display according to any one of claims 1 to 4, wherein a cured film is formed on at least one surface.   The laminated board for liquid crystal display protection in any one of Claims 1-5 used for a touchscreen.

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