Optical laminate, image display device equipped with the same, and method for manufacturing the optical laminate

Abstract

The present invention provides an optical laminate comprising a saponified cellulose resin film, a polarizer laminated to one side of the cellulose resin film, and a protective layer formed on the other side of the cellulose resin film, wherein the protective layer is formed from a protective layer-forming composition comprising a translucent resin having a viscosity of 5,000 cp or more at 60°C, a photoinitiator, and a solvent, and the translucent resin is a photocurable (meth)acrylate oligomer, an image display device equipped therewith, and a method for manufacturing the optical laminate. [Effect] By introducing a high-viscosity protective layer onto a saponified cellulose resin film, the optical laminate can ensure the adhesion and performance of the functional coating layer.

Description

[Technical Field]

[0001] The present invention relates to an optical laminate, an image display device equipped therewith, and a method for manufacturing the optical laminate, and more particularly to an optical laminate capable of ensuring adhesion and maintaining the performance of a functional coating layer when laminating a functional coating layer onto a cellulose-based substrate film, an image display device equipped therewith, and a method for manufacturing the optical laminate. [Background technology]

[0002] Image display devices such as liquid crystal displays, plasma displays, electroluminescent displays, touch panels, e-paper, and tablet PCs have expensive optical films like polarizers laminated into them. To prevent damage to these optical films, a cellulose-based protective film is often laminated onto the surface of the polarizer.

[0003] In recent years, there has been a growing demand for image display devices to exhibit diverse performance characteristics such as superior durability and visibility. Accordingly, research is being conducted on polarizing plates with a structure that incorporates additional functional coating layers to provide users with the desired performance.

[0004] However, in the manufacture of such polarizing plates, in order to improve adhesion with the polarizer, a cellulose-based film with a functional coating layer laminated on it is saponified, and then the polarizer is attached to the saponified surface to manufacture the polarizing plate. However, in this case, the performance of the laminated functional coating layer often deteriorates during the saponification process.

[0005] Korean Patent Publication No. 10-2014-0057484 discloses an antistatic hard coat film that maintains the performance of the hard coat layer even after saponification treatment with an alkaline aqueous solution, by forming it using an antistatic agent containing a quaternary ammonium salt and an ionizing radiation-curable resin containing a urethane-based polyfunctional acrylate compound having an isocyanuric acid skeleton and 15 functional (meth)acryloyl groups.

[0006] However, even with such hard coat films, the functional coating layer laminated on top of the hard coat layer is subjected to saponification treatment, which fundamentally prevents the deterioration of the performance of the functional coating layer. [Overview of the project] [Problems that the invention aims to solve]

[0007] One objective of the present invention is to provide an optical laminate in which a functional coating layer laminated on a cellulose-based substrate film can maintain adhesion and its original performance.

[0008] Another object of the present invention is to provide an image display device equipped with the optical laminate.

[0009] Another object of the present invention is to provide a method for manufacturing the optical laminate. [Means for solving the problem]

[0010] On the other hand, the present invention is An optical laminate comprising a saponified cellulose resin film, a polarizer laminated to one side of the cellulose resin film, and a protective layer formed on the other side of the cellulose resin film, The protective layer is formed from a protective layer-forming composition comprising a light-transmitting resin having a viscosity of 5,000 cp or more at 60°C, a photoinitiator, and a solvent. The aforementioned translucent resin provides an optical laminate containing a photocurable (meth)acrylate oligomer.

[0011] In one embodiment of the present invention, the photocurable (meth)acrylate oligomer may contain polyester acrylate.

[0012] In one embodiment of the present invention, the light-transmitting resin may further contain a compound represented by the following chemical formula 1. [Chemistry] In the above formula, The sum of n and m is 2.

[0013] In one embodiment of the present invention, the mixing ratio of the polyester acrylate and the compound represented by Chemical Formula 1 may be 60:40 to 80:20 on a weight basis.

[0014] In one embodiment of the present invention, one or more functional coating layers of a hard coating layer, an antireflection layer, and a conductive layer may be further formed on the protective layer.

[0015] On the other hand, the present invention provides an image display device provided with the optical laminate.

[0016] On the other hand, the present invention (a) A step of saponifying a cellulose-based resin film; (b) A step of laminating a polarizer on one surface of the saponified cellulose-based resin film; (c) A method for manufacturing an optical laminate including a step of applying a composition for forming a protective layer on the other surface of the cellulose resin film to form a protective layer, The composition for forming the protective layer includes a light-transmitting resin having a viscosity of 5,000 cp or more at 60°C, a photoinitiator, and a solvent, The light-transmitting resin provides a manufacturing method including a photocurable (meth)acrylate oligomer. [Advantages of the Invention]

[0017] The optical laminate according to the present invention can ensure the adhesion and performance of the functional coating layer by introducing a high-viscosity protective layer on the saponified cellulose-based resin film. [Embodiments for Carrying Out the Invention] ]

[0018] Hereinafter, the present invention will be described in more detail.

[0019] One embodiment of the present invention is an optical laminate including a saponified cellulose-based resin film, a polarizer laminated on one surface of the cellulose-based resin film, and a protective layer formed on the other surface of the cellulose-based resin film, wherein the protective layer is formed from a composition for forming a protective layer including a light-transmissive resin having a viscosity of 5,000 cp or more at 60° C., a photoinitiator, and a solvent, the light-transmissive resin relates to an optical laminate including a photocurable (meth)acrylate oligomer.

[0020] The optical laminate according to one embodiment of the present invention includes a protective layer formed by using a light-transmissive resin including a photocurable (meth)acrylate oligomer and having a viscosity of 5,000 cp or more at 60° C. on the other surface of a saponified cellulose-based resin film after laminating a polarizer on one surface of the saponified cellulose-based resin film, whereby the adhesion to a functional coating layer formed on the protective layer can be maintained high. Further, the optical laminate according to one embodiment of the present invention can form a functional coating layer on the saponified cellulose-based resin film and can prevent a decrease in the performance of the functional coating layer due to the saponification treatment.

[0021] In one embodiment of the present invention, the cellulose-based resin film may be composed of an ester of cellulose and a fatty acid, and any resin film that can enhance the adhesion to a polarizer by saponification can be used without particular limitation. Specific examples include cellulose triacetate resin, cellulose diacetate resin, cellulose tripropionate resin, cellulose dipropionate resin, etc. Among these, cellulose triacetate (triacetyl cellulose) resin having excellent transparency and adhesion is preferable.

[0022] The thickness of the cellulose-based resin film may be 30 to 100 μm, and more preferably 40 to 80 μm.

[0023] The aforementioned saponification treatment is performed because the surface of cellulose resin films, particularly triacetylcellulose films, is hydrophobic, resulting in poor adhesion to polyvinyl alcohol films, which are mainly used as polarizers. The purpose of this treatment is to improve the adhesion between the cellulose resin film and the polarizer by surface modification.

[0024] The saponification treatment may be carried out by known methods, for example, by immersing the triacetylcellulose film in an alkaline solution, then washing it with water and drying it.

[0025] Examples of alkaline solutions used in the saponification treatment include aqueous solutions of sodium hydroxide, potassium hydroxide, etc., or alkaline aqueous solutions to which various organic solvents such as alcohol have been added. The conditions for the saponification treatment are not particularly limited, but it is preferable to use an aqueous solution with a concentration of 0.1 to 10 N, and more preferably a concentration of 1 to 2 N. The temperature of the alkaline aqueous solution is preferably 0 to 100°C, and more preferably 40 to 60°C. The saponification treatment time is 1 to 120 seconds, preferably about 10 to 40 seconds.

[0026] The polarizer may be obtained by swelling, dyeing, crosslinking, stretching, washing, and drying a polarizer-forming film commonly used in this field.

[0027] The polarizer-forming film is not particularly limited in type as long as it is a film that can be dyed with a dichroic substance, such as iodine. Examples include polyvinyl alcohol (PVA) film, dehydrated polyvinyl alcohol film, dehydrochlorinated polyvinyl alcohol film, polyethylene terephthalate film, ethylene-vinyl acetate copolymer film, ethylene-vinyl alcohol copolymer film, cellulose film, and partially saponified films thereof. Among these, polyvinyl alcohol-based films are preferred because they not only have an excellent effect in enhancing the uniformity of polarization degree within the plane, but also have excellent dyeing affinity for iodine.

[0028] The lamination of the cellulose resin film and the polarizer may be carried out via an adhesive, and any adhesive well known in the industry may be used without particular limitation. Specifically, examples include isocyanate-based, polyvinyl alcohol-based, gelatin-based, vinyl polymer-based latex-type, and water-soluble polyester-based adhesives. Both water-based and non-water-based adhesives may be used, but water-based adhesives are more preferred, and specifically, they may contain 0.5 to 60% by weight of solids.

[0029] In one embodiment of the present invention, the protective layer is formed from a protective layer-forming composition comprising a light-transmitting resin having a viscosity of 5,000 cP or more at 60°C, preferably 5,000 to 7,000 cP, a photoinitiator, and a solvent, wherein the light-transmitting resin comprises a photocurable (meth)acrylate oligomer.

[0030] In one embodiment of the present invention, the photocurable (meth)acrylate oligomer may contain polyester acrylate.

[0031] The aforementioned polyester acrylate may be produced by reacting a polyester polyol with acrylic acid using a method known in the industry.

[0032] The polyester acrylate may be, for example, one or more selected from the group consisting of polyester monoacrylate, polyester diacrylate, polyester tetraacrylate, polyester hexaacrylate, polyester pentaerythritol triacrylate, polyester pentaerythritol tetraacrylate, and polyester pentaerythritol hexaacrylate, but is not limited to these. In particular, a bifunctional polyester acrylate is preferred in terms of suppressing surface haze and ensuring adhesion.

[0033] In one embodiment of the present invention, the translucent resin may further contain, in addition to the polyester acrylate, a compound represented by the following chemical formula 1. [ka] In the above formula, The sum of n and m is 2.

[0034] When using the polyester acrylate in combination with the compound represented by chemical formula 1, the mixing ratio of the polyester acrylate and the compound represented by chemical formula 1 may be 60:40 to 80:20 by weight, preferably 65:35 to 75:25.

[0035] In one embodiment of the present invention, the translucent resin may be present in an amount of 1 to 60% by weight, preferably 10 to 50% by weight, relative to 100% by weight of the total protective layer forming composition. If the translucent resin content is less than 1% by weight, the film thickness of the coating becomes excessively thin, making it difficult to achieve sufficient hardness improvement. If it exceeds 60% by weight, the film thickness of the coating becomes excessively thick, leading to problems such as severe curling.

[0036] A protective layer-forming composition according to one embodiment of the present invention may further contain a translucent resin having a viscosity of less than 5,000 cp at 60°C, preferably 500 to 3,000 cp, for example, a monomer having a (meth)acryloyl group.

[0037] The monomers having the (meth)acryloyl group include, as specific examples, neopentyl glycol acrylate, 1,6-hexanediol di(meth)acrylate, propylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate. It may be one or more selected from the group consisting of 1,2,4-cyclohexanetetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, isooctyl(meth)acrylate, isodecyl(meth)acrylate, stearyl(meth)acrylate, tetrahydrofurfuryl(meth)acrylate, phenoxyethyl(meth)acrylate, and isoborneol(meth)acrylate.

[0038] In particular, pentaerythritol tri(meth)acrylate is preferred in terms of ensuring adhesion to the saponified substrate and crosslinking with the polyester acrylate.

[0039] The monomer having a (meth)acryloyl group may be included in an amount of 40% by weight or less, for example, 3 to 40% by weight, based on 100% by weight of the entire protective layer-forming composition. Including the monomer having a (meth)acryloyl group in the amount within the above range is preferable because it allows the polymerization rate of the protective layer film to be adjusted to an appropriate level, thereby improving adhesion with the functional coating layer formed on the protective layer.

[0040] In one embodiment of the present invention, the photoinitiator is included for photocuring induction of the protective layer forming composition and may be used without limitation as long as it is used in the art. For example, one or more selected from the group consisting of hydroxyketones, aminoketones, hydrogen abstraction type photoinitiators, and combinations thereof may be used.

[0041] Specifically, the photoinitiator may be one or more selected from the group consisting of 2-methyl-1-[4-(methylthio)phenyl]2-morpholinepropanone-1, diphenyl ketone, benzyldimethyl ketal, 2-hydroxy-2-methyl-1-phenyl-1-one, 4-hydroxycyclophenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, anthraquinone, fluorene, triphenylamine, carbazole, 3-methylacetophenone, 4-chloroacetophenone, 4,4-dimethoxyacetophenone, 4,4-diaminobenzophenone, 1-hydroxycyclohexylphenyl ketone, benzophenone, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, and combinations thereof.

[0042] In one embodiment of the present invention, the photoinitiator may be present in an amount of about 0.1 to 10% by weight, preferably about 1 to 8% by weight, based on 100% by weight of the entire protective layer forming composition. If the photoinitiator content is less than 0.1% by weight, the curing rate of the composition is slow, resulting in uncured material and reduced mechanical properties. If it exceeds 10% by weight, overcuring may cause cracks in the coating film.

[0043] In one embodiment of the present invention, the solvent can be used without particular limitations as long as it is capable of dissolving or dispersing the aforementioned composition and is well known in the art. Usable solvents include alcohol-based solvents (methanol, ethanol, isopropanol, butanol, methyl cellosolve, ethyl cellosolve, etc.), ketone-based solvents (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, cyclohexanone, etc.), and acetate-based solvents (ethyl acetate, propyl acetate, n-butyl acetate, t-butyl acetate, methyl cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether acetate, propylene Examples of solvents include diethylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, methoxybutyl acetate, methoxypentyl acetate, etc., hexane-based (hexane, heptane, octane, etc.), benzene-based (benzene, toluene, xylene, etc.), and ether-based (diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, propylene glycol monomethyl ether, etc.). The solvents exemplified above may be used individually or in combination of two or more.

[0044] In one embodiment of the present invention, the solvent may be present in an amount of 10 to 95% by weight, preferably 30 to 95% by weight, and more preferably 40 to 80% by weight, based on 100% by weight of the entire protective layer forming composition. If the solvent content is less than the above amount, the viscosity will be high and workability will be reduced, and it may become difficult to adequately sweep the base film. Conversely, if it exceeds the above range, the drying process will take a long time and economic efficiency will be reduced.

[0045] In one embodiment of the present invention, the protective layer forming composition may further contain additives such as a leveling agent, an ultraviolet stabilizer, and a heat stabilizer.

[0046] The leveling agent is a component that imparts smoothness and coating properties to the coating film, and may include silicone-based leveling agents, fluorine-based leveling agents, acrylic polymer-based leveling agents, and the like. These may be used individually or in combination of two or more types.

[0047] The silicone-based leveling agent may include organically modified polysiloxanes such as polyether-modified, polyester-modified, or aralkyl-modified polysiloxanes. In particular, the silicone-based leveling agent may include polyether-modified polysiloxanes from the perspective of controlling the surface tension of the protective layer.

[0048] The polyether-modified polysiloxane may be an alkylene oxide-modified polysiloxane such as ethylene oxide, propylene oxide, butylene oxide, or tetramethylene oxide. Specifically, examples include polydialkylsiloxanes modified with ethylene oxide and / or propylene oxide (such as polydimethylsiloxane, polydiethylsiloxane, polydipropylsiloxane, polydibutylsiloxane, or polydipentylsiloxane). For example, the polyether-modified polysiloxane may be a side-chain polyether-modified polydialkylsiloxane, a terminal polyether-modified polydialkylsiloxane, or a side-chain terminal polydialkylsiloxane.

[0049] Examples of commercially available silicone-based leveling agents include the following product names: BYK-300, BYK-302, BYK-306, BYK-307, BYK-320, BYK-325, BYK-330, BYK-331, BYK-333, BYK-337, BYK-341, BYK-344, BYK-345, BYK-346, BYK-348, BYK-377, BYK-378, BYK-UV3500, BYK-3510, BYK-3530, BYK-3570 ( Examples include the above (manufactured by BYK), FZ-2118, FZ-77, FZ-2161 (all manufactured by Toray Dow Corning Co., Ltd.), KP321, KP323, KP324, KP326, KP340, KP341 (all manufactured by Shin-Etsu Chemical Co., Ltd.), TSF4440, TSF4441, TSF4445, TSF4450, TSF4446, TSF4452, TSF4453, TSF4460 (all manufactured by Momentive Performance Materials).

[0050] In one embodiment of the present invention, the leveling agent may be included in an amount of 0.01 to 10% by weight relative to 100% by weight of the total protective layer forming composition. If the content of the leveling agent is below the above content range, it may be difficult to achieve sufficient smoothness of the optical film, and if it exceeds the above content range, the hardness and scratch characteristics of the optical film may decrease.

[0051] The aforementioned UV stabilizer is a component that blocks or absorbs ultraviolet light, preventing decomposition, discoloration, and embrittlement of the cured coating film due to exposure to ultraviolet light.

[0052] The aforementioned ultraviolet stabilizers are classified into absorbers, quenchers, and hindered amine light stabilizers (HALS) according to their mechanism of action. They can also be classified into phenyl salicylate (absorber), benzophenone (absorber), benzotriazole (absorber), nickel derivatives (quencher), and radical scavengers according to their chemical structure. The aforementioned ultraviolet stabilizers are not particularly limited as long as they do not significantly alter the initial hue of the coating film.

[0053] Furthermore, as commercially applicable products, heat stabilizers may be used individually or in combination, including primary heat stabilizers (polyphenol-based), and secondary heat stabilizers (phospide-based and lactone-based).

[0054] The UV stabilizer and heat stabilizer may be used with appropriate adjustments to their content, within a range that does not affect UV curability.

[0055] A protective layer according to one embodiment of the present invention may be formed by applying the above-described protective layer-forming composition onto a saponified cellulose resin film, drying it, and then UV curing it.

[0056] The protective layer-forming composition can be coated onto a substrate layer using known methods such as die coater, air knife, reverse roll, spray, blade, casting, gravure, microgravure, and spin coating.

[0057] After applying the protective layer-forming composition onto the resin film, the volatile matter is evaporated and dried at a temperature of 30 to 150°C for 10 seconds to 1 hour, more specifically, 30 seconds to 30 minutes, and then cured by irradiation with UV light. The amount of UV light irradiated is specifically about 0.01 to 10 J / cm². 2 It is acceptable to have a density of 0.1 to 2 J / cm², more specifically, 0.1 to 2 J / cm². 2 That's fine.

[0058] In this case, the thickness of the protective layer formed may be specifically 1 to 30 μm, and more specifically 3 to 20 μm. When the thickness of the protective layer falls within this range, excellent hardness, flexibility, and curl characteristics can be obtained.

[0059] An optical laminate according to one embodiment of the present invention may further include one or more functional coating layers, selected from a hard coating layer, an anti-reflective layer, and a conductive layer, on the protective layer.

[0060] The hard coating layer is preferably one that exhibits excellent hard coating properties, sufficient strength after the formation of the film layer, and excellent light transmittance. Examples of resins for forming the hard coating layer include thermosetting resins, thermoplastic resins, ultraviolet curing resins, electron beam curing resins, and two-component mixed resins. Among these, ultraviolet curing resins are preferred because they allow for the efficient formation of a hard coating layer with simple processing operations during curing by ultraviolet irradiation.

[0061] Examples of UV-curable resins include polyester-based, acrylic-based, urethane-based, amide-based, silicone-based, and epoxy-based resins, and include UV-curable monomers, oligomers, and polymers. Preferably used UV-curable resins include those having UV-polymerizable functional groups, and among these, those containing acrylic monomer or oligomer components having two or more such functional groups, particularly three to six. The resin is formulated with a UV polymerization initiator.

[0062] The method for forming the hard coating layer is not particularly limited, and any appropriate method may be adopted. For example, a method may be employed in which the hard coating composition is applied to the protective layer described above, dried, and then cured. The hard coating composition can be applied by an appropriate method such as fountain coating, die coating, casting, spin coating, fountain metering, or gravure coating. Furthermore, in the application process, it is preferable to prepare the hard coating composition as a solution by diluting it with a common solvent such as toluene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, isopropyl alcohol, or ethyl alcohol. The thickness of the hard coating layer is not particularly limited, but it is preferably about 0.5 to 30 μm, and particularly preferably 3 to 15 μm.

[0063] The aforementioned anti-reflective layer is a film that minimizes external light reflectivity and maximizes the contrast ratio (white brightness / black brightness) to maximize image quality.

[0064] The anti-reflective layer may employ any suitable configuration, and typical configurations include a single low-refractive-index layer or a multilayer thin film in which a low-refractive-index layer and a high-refractive-index layer are sequentially laminated.

[0065] In this invention, the low refractive index layer refers to a low refractive index coating layer having a refractive index of 1.38 to 1.48 and a thickness of 0.05 to 10.0 μm, and the high refractive index layer refers to a high refractive index coating layer having a refractive index of 1.58 to 1.70 and a thickness of 30 to 100 nm. The low refractive index layer and the high refractive index layer are formed by preparing a coating solution containing a binder resin mainly composed of an ionizing radiation-curable resin and inorganic fine particles for adjusting the refractive index, and then drying and curing it according to a commonly used method. For example, the low refractive index layer can be obtained using a coating solution obtained by further adding inorganic fine particles having a low refractive index, such as silica or hollow silica fine particles with a particle size of 0.001 μm to 0.2 μm. On the other hand, the high refractive index layer can be obtained using a coating solution obtained by further adding fine particles having a high refractive index, such as tin-containing antimony oxide particles, zinc-containing antimony oxide particles, tin-containing indium oxide particles, zinc oxide / aluminum oxide particles, or antimony oxide particles.

[0066] On the other hand, the ionizing radiation-curable resin contained in the coating solution preferably contains (meth)acrylic resin, polyurethane resin, polyester resin, polyether resin, olefin resin, and polyimide resin as a skeletal structure, and may be a polymer oligomer having 3 to 10 repeating units of the resin.

[0067] The conductive layer is a layer made of a composition containing a conductive substance.

[0068] The conductive layer is formed from a conductive layer-forming composition comprising a polythiophene-based conductive polymer and an alcohol solvent.

[0069] The polythiophene-based conductive polymer may be poly(3,4-ethylenedioxythiophene) (PEDOT:PSS) doped with poly(styrene sulfonate, PSS).

[0070] Poly(3,4-ethylenedioxythiophene) (PEDOT) has high electrical conductivity and low resistance, which facilitates electron transfer and allows for the provision of excellent conductive properties.

[0071] The weight ratio of poly(3,4-ethylenedioxythiophene) (PEDOT) to poly(styrenesulfonate) (PSS) may be 1:1 to 5.

[0072] The aforementioned polythiophene-based conductive polymer may be obtained commercially or manufactured using methods well known in the art.

[0073] Specifically, PEDOT:PSS may be produced by oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) in an aqueous solution, using PSS as a template to balance the charge. PEDOT:PSS produced according to this method can be stably dispersed as polymer gel particles in an aqueous solution without separating from each other, because PEDOT is very strongly ionically bonded to the PSS polymer chains.

[0074] The aforementioned alcohol solvent may include, but is not limited to, methanol, ethanol, isopropanol, and butanol.

[0075] The conductive layer may be formed by applying the conductive layer-forming composition onto the protective layer, hard coating layer, or anti-reflective layer described above, drying it, and then heat-curing it.

[0076] The conductive layer forming composition can be coated onto a substrate using known methods such as die coating, air knife, reverse roll, spray, blade, casting, gravure, microgravure, and spin coating.

[0077] After applying the conductive layer-forming composition to the substrate, it can be dried at 60 to 100°C for 1 to 10 minutes to form the layer. The drying may be carried out, for example, by hot air drying.

[0078] One embodiment of the present invention relates to an image display device equipped with the optical laminate described above.

[0079] The image display device according to one embodiment of the present invention is applicable not only to conventional liquid crystal displays but also to various other image display devices such as organic EL displays, plasma displays, and field emission displays.

[0080] The image display device of the present invention may further include, in addition to the optical laminate, configurations known in the art.

[0081] One embodiment of the present invention relates to a method for manufacturing the optical laminate, and the method for manufacturing the optical laminate according to one embodiment of the present invention is: (a) A step of saponifying the cellulose resin film; (b) The step of laminating a polarizer to one side of the saponified cellulose resin film; (c) The step of applying a protective layer-forming composition to the other surface of the cellulose resin film to form a protective layer.

[0082] Specifically, the method for manufacturing an optical laminate according to one embodiment of the present invention involves first saponifying a cellulose resin film.

[0083] The type and thickness of the cellulose resin film are the same as those described for the optical laminate, and the saponification treatment of the cellulose resin film is the same as that described for the optical laminate; therefore, to avoid redundancy, a detailed explanation will be omitted.

[0084] Next, a polarizer is laminated to one side of the saponified cellulose resin film.

[0085] The manufacturing method and types of the polarizer are the same as those described for the optical laminate, and the lamination of the cellulose resin film and the polarizer is the same as described for the optical laminate; therefore, to avoid duplication, a detailed explanation will be omitted.

[0086] Next, a protective layer is formed by applying a protective layer-forming composition to the other surface of the cellulose resin film.

[0087] The protective layer-forming composition comprises a translucent resin having a viscosity of 5,000 cp or more at 60°C, a photoinitiator, and a solvent, wherein the translucent resin comprises a photocurable (meth)acrylate oligomer.

[0088] The components and content of the translucent resin, photoinitiator, and solvent having a viscosity of 5,000 cp or more at 60°C are the same as those described for the optical laminate, and the application of the protective layer-forming composition and the formation of the protective layer are the same as those described for the optical laminate; therefore, to avoid duplication, a detailed explanation is omitted.

[0089] A method for manufacturing an optical laminate according to one embodiment of the present invention may further include the step of forming one or more functional coating layers, selected from a hard coating layer, an anti-reflective layer, and a conductive layer, on the protective layer.

[0090] Since the hard coating layer, anti-reflective layer, and conductive layer are the same as those described for the optical laminate, a detailed explanation will be omitted to avoid redundancy.

[0091] The present invention will be described in more detail below with reference to examples, comparative examples, and experimental examples. It should be noted that these examples, comparative examples, and experimental examples are merely for illustrative purposes, and it will be obvious to those skilled in the art that the scope of the present invention is not limited thereto.

[0092] Manufacturing Example 1: Manufacturing of a protective layer-forming composition A composition for forming a protective layer was prepared by mixing 37.4 parts by weight of a bifunctional polyester acrylate (MIRAMER PS2500, manufactured by Miwon Specialty Chemicals, 60°C, 6,000 cP), 2.4 parts by weight of a photoinitiator (Irgacure-184, manufactured by Ciba Specialty Chemicals), 0.2 parts by weight of a leveling agent (BYK-3530, manufactured by BYK), and 60 parts by weight of methyl ethyl ketone using a stirrer, and filtering the mixture through a PP filter.

[0093] Manufacturing Example 2: Manufacturing of a protective layer-forming composition A composition for forming a protective layer was prepared by mixing 18.7 parts by weight of trifunctional acrylate (MIRAMER M340, manufactured by Miwon Specialty Chemicals, 25°C, 1,000-1,800 cP), 18.7 parts by weight of bifunctional polyester acrylate (MIRAMER PS2500, manufactured by Miwon Specialty Chemicals, 60°C, 6,000 cP), 2.4 parts by weight of photoinitiator (Irgacure-184, manufactured by Ciba Specialty Chemicals), 0.2 parts by weight of leveling agent (BYK-3530, manufactured by BYK), and 60 parts by weight of methyl ethyl ketone using a stirrer, and filtering the mixture through a PP filter.

[0094] Manufacturing Example 3: Manufacturing of a protective layer-forming composition A composition for forming a protective layer was prepared by mixing 26.2 parts by weight of trifunctional acrylate (MIRAMER M340, manufactured by Miwon Specialty Chemicals, 25°C, 1,000-1,800 cP), 11.2 parts by weight of bifunctional polyester acrylate (MIRAMER PS2500, manufactured by Miwon Specialty Chemicals, 60°C, 6,000 cP), 2.4 parts by weight of photoinitiator (Irgacure-184, manufactured by Ciba Specialty Chemicals), 0.2 parts by weight of leveling agent (BYK-3530, manufactured by BYK), and 60 parts by weight of methyl ethyl ketone using a stirrer, and filtering the mixture through a PP filter.

[0095] Manufacturing Example 4: Manufacturing of a Hard Coating Composition A hard coating composition was prepared by mixing 46.7 parts by weight of hexafunctional urethane acrylate (UA-306I, manufactured by Kyoeisha Chemical Co., Ltd.), 3 parts by weight of photoinitiator (Irgacure-184, manufactured by Ciba Specialty Chemicals), 0.3 parts by weight of leveling agent (BYK-307, manufactured by BYK) and 50 parts by weight of methyl ethyl ketone using a stirrer, and filtering the mixture using a PP filter.

[0096] Manufacturing Example 5: Manufacturing of Hard Coating Composition A hard coating composition was prepared by mixing 4.7 parts by weight of 14-functional acrylate (VISCOAT #1000, manufactured by Osaka Organic Chemical Industry Co., Ltd.), 42.1 parts by weight of 6-functional urethane acrylate (UA-306I, manufactured by Kyoeisha Chemical Co., Ltd.), 3 parts by weight of photoinitiator (Irgacure-184, manufactured by Ciba Specialty Chemicals), 1 part by weight of leveling agent (KY-1203, manufactured by Shin-Etsu Chemical Co., Ltd.), and 49.2 parts by weight of methyl ethyl ketone using a stirrer and filtering the mixture through a PP filter.

[0097] Manufacturing Example 6: Manufacturing of a composition for forming an anti-reflective layer A composition for forming an anti-reflective layer was prepared by mixing 1 part by weight of hexafunctional urethane acrylate (manufactured by Kyoeisha Chemical Co., Ltd., UA-306I), 0.1 parts by weight of photoinitiator (Irgacure-184, manufactured by Ciba Specialty Chemicals), 0.1 parts by weight of leveling agent (BYK-307, manufactured by BYK), 9 parts by weight of 60 nm hollow silica, and 89.8 parts by weight of methyl ethyl ketone using a stirrer, and filtering the mixture using a PP filter.

[0098] Manufacturing Example 7: Manufacturing of a composition for forming a conductive layer A composition for forming a conductive layer was prepared by mixing 18.2 parts by weight of PEDOT:PSS (manufactured by Shin-Etsu Polymer Co., Ltd., SAS-P) and 81.8 parts by weight of isopropyl alcohol using a stirrer, and filtering the mixture through a PP filter.

[0099] Manufacturing Example 8: Manufacturing of a protective layer-forming composition A protective layer-forming composition was prepared by mixing 37.4 parts by weight of trifunctional acrylate (MIRAMER M340, manufactured by Miwon Specialty Chemicals, 25°C, 1,000-1,800 cP), 2.4 parts by weight of photoinitiator (Irgacure-184, manufactured by Ciba Specialty Chemicals), 0.2 parts by weight of leveling agent (BYK-3530, manufactured by BYK), and 60 parts by weight of methyl ethyl ketone using a stirrer, and filtering the mixture through a PP filter.

[0100] [Table 1] A-1: Dual-functional polyester acrylate (MIRAMER PS2500, manufactured by Miwon Specialty Chemicals, 60℃, 6,000cP) A-2:3 Functional Acrylate (MIRAMER M340, manufactured by Miwon Specialty Chemicals, 25℃, 1,000~1,800cP) B: Irgacure-184 (manufactured by Ciba Specialty Chemicals) C-1: Leveling agent (BYK-3530, manufactured by BYK) C-2: Leveling agent (BYK-307, manufactured by BYK) C-3: Leveling agent (KY-1203, manufactured by Shin-Etsu Chemical Co., Ltd.) D-1: Methyl ethyl ketone D-2: Isopropyl alcohol Hexafunctional acrylate: Urethane acrylate (UA-306I, manufactured by Kyoeisha Chemical Co., Ltd.) 14-Functional Acrylate: VISCOAT #1000 (Manufactured by Osaka Organic Chemical Industry Co., Ltd.) Conductive polymer: PEDOT:PSS (SAS-P, manufactured by Shin-Etsu Polymer Co., Ltd.)

[0101] Example 1: Manufacturing of an optical laminate After saponifying a triacetylcellulose film with a thickness of 80 μm, a polarizer is bonded to one side using a modified polyvinyl alcohol-based adhesive to form a polarizing plate. The other side of the saponified triacetylcellulose film is then coated with the protective layer-forming composition from Production Example 1 to a thickness of 3 μm and dried. Finally, it is subjected to UV integrated light intensity of 600 mJ / cm² under a nitrogen atmosphere. 2 An optical laminate was manufactured by irradiating it with light.

[0102] Example 2: Manufacturing of an optical laminate An optical laminate was manufactured in the same manner as in Example 1, except that the protective layer forming composition of Manufacturing Example 2 was used instead of the protective layer forming composition of Manufacturing Example 1.

[0103] Example 3: Manufacturing of an optical laminate An optical laminate was manufactured in the same manner as in Example 1, except that the protective layer forming composition of Manufacturing Example 3 was used instead of the protective layer forming composition of Manufacturing Example 1.

[0104] Example 4: Manufacturing of an optical laminate The hard coating composition of Production Example 5 was coated onto the protective layer formed in Example 2 to a thickness of 5 μm and dried, and then exposed to UV integrated light of 600 mJ / cm² under a nitrogen atmosphere. 2 An optical laminate was manufactured by irradiating it with light.

[0105] Example 5: Manufacturing of an optical laminate The hard coating composition of Manufacturing Example 4 was coated onto the protective layer formed in Example 2 to a thickness of 5 μm and dried, and then exposed to UV light at an integrated intensity of 600 mJ / cm² under a nitrogen atmosphere. 2 A hard coating layer is formed by irradiation, and the anti-reflective layer forming composition of Production Example 6 is coated on it to a thickness of 100 nm, dried, and then subjected to UV integrated light of 600 mJ / cm² under a nitrogen atmosphere. 2 An optical laminate was manufactured by irradiating it with light.

[0106] Example 6: Manufacturing of an optical laminate An optical laminate was manufactured by coating the protective layer formed in Example 2 with the conductive layer-forming composition of Manufacturing Example 7 to a thickness of 100 nm and then thermal curing it.

[0107] Comparative Example 1: Manufacturing of Optical Laminates An optical laminate was manufactured in the same manner as in Example 1, except that the protective layer forming composition of Manufacturing Example 8 was used instead of the protective layer forming composition of Manufacturing Example 1.

[0108] Comparative Example 2: Manufacturing of Optical Laminates An optical laminate was manufactured in the same manner as in Example 1, except that the hard coating composition of Manufacturing Example 5 was applied to a thickness of 5 μm instead of the protective layer forming composition of Manufacturing Example 1.

[0109] Comparative Example 3: Manufacturing of Optical Laminates One side of a triacetylcellulose film with a thickness of 80 μm is coated with the hard coating composition of Production Example 5 to a thickness of 5 μm, dried, and then exposed to UV integrated light of 600 mJ / cm² under a nitrogen atmosphere. 2 A hard coating layer was formed by irradiation, and after saponification of the triacetylcellulose film with the hard coating layer, a polarizer was bonded to the other side using a modified polyvinyl alcohol-based adhesive to produce an optical laminate.

[0110] Comparative Example 4: Manufacturing of Optical Laminates After saponifying a triacetylcellulose film with a thickness of 80 μm, a polarizer is bonded to one side using a modified polyvinyl alcohol-based adhesive to form a polarizing plate. The hard coating composition of Production Example 4 is then coated onto the other side of the saponified triacetylcellulose film to a thickness of 5 μm and dried. Finally, it is subjected to UV integrated light intensity of 600 mJ / cm² under a nitrogen atmosphere. 2Irradiate to form a hard coating layer, coat the antireflection layer-forming composition of Production Example 6 on the hard coating layer to a thickness of 100 nm, dry it, and then irradiate it with a UV integrated light quantity of 600 mJ / cm 2 to produce an optical laminate.

[0111] Comparative Example 5: Production of an optical laminate Coat the hard coating composition of Production Example 4 on one surface of a triacetyl cellulose film having a thickness of 80 μm to a thickness of 5 μm, dry it, and then irradiate it with a UV integrated light quantity of 600 mJ / cm 2 to form a hard coating layer. Coat the antireflection layer-forming composition of Production Example 6 on the hard coating layer to a thickness of 100 nm, dry it, and then irradiate it with a UV integrated light quantity of 600 mJ / cm 2 to form an antireflection layer. After saponification is performed on the triacetyl cellulose film on which the hard coating layer and the antireflection layer are formed, a polarizer is bonded to the other surface using a modified polyvinyl alcohol-based adhesive to produce an optical laminate.

[0112] Comparative Example 6: Production of an optical laminate An optical laminate was produced in the same manner as in Example 1, except that the conductive layer-forming composition of Production Example 7 was coated to a thickness of 100 nm and heat-cured to form a conductive layer instead of the protective layer-forming composition of Production Example 1.

[0113] Comparative Example 7: Production of an optical laminate An optical laminate was produced in the same manner as in Comparative Example 3, except that the conductive layer-forming composition of Production Example 7 was coated to a thickness of 100 nm and heat-cured to form a conductive layer instead of the hard coating composition of Production Example 5.

[0114] Experimental Example 1: For the optical laminates produced in the above Examples and Comparative Examples, physical properties were measured as follows, and the results are shown in Tables 2 and 3 below.

[0115] (1) Water contact angle After dropping 2 μl of water onto the surface of the coating layer of the optical laminates manufactured in the above examples and comparative examples, the water contact angle was measured using a DSA100 manufactured by KRUSS.

[0116] (2) Adhesion The optical laminates manufactured in the above examples and comparative examples were bonded to a glass using a transparent adhesive with the coating layer facing upwards. Then, cuts were made in the coating surface using a utility knife to create 100 square shapes at 1 mm intervals vertically and horizontally. Three adhesion tests were then performed using Nichiban tape. After rapidly peeling from a 180-degree peeling angle, the extent to which the coating surface peeled off was visually observed, and the adhesion was evaluated based on the following evaluation criteria. <Evaluation Criteria> 5B: No peeling 4B: Peeling of more than 0% but less than 5% 3B: 5% to less than 15% peeling 2B: 15% to less than 35% peeling 1B: 35% to less than 65% peeling 0B: More than 65% peeling

[0117] (3)Reflectance The optical laminates manufactured in the above examples and comparative examples were bonded to a black acrylic plate to remove back surface reflections, and then the reflectance was measured using an integrating sphere reflectance analyzer (CM-3700A, manufactured by Konica Minolta).

[0118] (4) Scratch resistance After fixing the optical laminates produced in the above manufacturing examples and comparative examples with tape so that the hard coating layer is facing upwards, 250 g / cm³ of steel wool (#0000) was used. 2 The sample was subjected to 3,500 reciprocating friction cycles under a load, and then the measurement section was illuminated by a three-wavelength lamp, with light transmitted and reflected to observe the scratches. Scratch resistance was evaluated based on the following evaluation criteria. <Evaluation Criteria> ○: No scratches are visible, or five or fewer scratches are visible. ×: More than 5 scratches are visible.

[0119] (5) Haze measurement The haze of the optical laminates manufactured in the above examples and comparative examples was measured using a haze meter (HM-150N, manufactured by Murakami Color Technology Laboratory).

[0120] (6)Surface resistance The surface resistance of the optical laminates manufactured in the above examples and comparative examples was measured using a CMT-100A (manufactured by AIT Co., Ltd.). [Table 2] [Table 3]

[0121] As shown in Table 2 above, the optical laminates of Examples 1 to 6, in which a protective layer was formed using a translucent resin containing a photocurable (meth)acrylate oligomer on one side of a saponified cellulose resin film and having a viscosity of 5,000 cp or more at 60°C, showed excellent adhesion of the coating layer and good maintenance of the coating layer's performance.

[0122] On the other hand, as shown in Table 3, when forming a protective layer on one side of the saponified cellulose resin film, it was confirmed that in the optical laminates of Comparative Examples 1 to 7, where a light-transmitting resin containing a photocurable (meth)acrylate oligomer and having a viscosity of 5,000 cp or more at 60°C was not used, or where no protective layer was formed, or where a coating layer was formed on one side of the cellulose resin film before saponification, the adhesion of the coating layer was reduced or the performance of the coating layer was poor.

[0123] Although specific parts of the present invention have been described in detail above, it is clear to any person with ordinary skill in the art to which the present invention belongs that such specific descriptions are merely preferred examples and do not limit the scope of the present invention. A person with ordinary skill in the art to which the present invention belongs will be able to make various applications and modifications within the scope of the present invention based on the above content.

[0124] Therefore, the substantial scope of the present invention can be defined by the claims and their equivalents.

Claims

1. An optical laminate comprising a saponified cellulose resin film, a polarizer laminated to one side of the cellulose resin film, and a protective layer formed on the other side of the cellulose resin film, The protective layer is formed from a protective layer-forming composition comprising a light-transmitting resin having a viscosity of 5,000 cp or more at 60°C, a photoinitiator, and a solvent. The aforementioned translucent resin is an optical laminate containing a photocurable (meth)acrylate oligomer.

2. The optical laminate according to claim 1, wherein the photocurable (meth)acrylate oligomer includes polyester acrylate.

3. The optical laminate according to claim 2, wherein the light-transmitting resin further comprises a compound represented by the following chemical formula 1. 【Chemistry 1】 In the above formula, The sum of n and m is 2.

4. The optical laminate according to claim 3, wherein the mixing ratio of the polyester acrylate and the compound represented by chemical formula 1 is 60:40 to 80:20 by weight.

5. The optical laminate according to claim 1, wherein one or more functional coating layers, selected from a hard coating layer, an anti-reflective layer, and a conductive layer, are further formed on the protective layer.

6. An image display device comprising an optical laminate according to any one of claims 1 to 5.

7. (a) The step of saponifying the cellulose resin film; (b) The step of laminating a polarizer to one side of the saponified cellulose resin film; (c) A method for manufacturing an optical laminate, comprising the step of applying a protective layer-forming composition to the other surface of the cellulose resin film to form a protective layer, The protective layer-forming composition comprises a light-transmitting resin having a viscosity of 5,000 cp or more at 60°C, a photoinitiator, and a solvent. A method for producing the aforementioned translucent resin, comprising a photocurable (meth)acrylate oligomer.

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