Optical laminates and image display devices

Abstract

This invention provides an optical laminate and an image display device that can sufficiently cure an ultraviolet-curable silicone adhesive composition within a certain time, even when laminating a polarizing plate having a hard coat layer on its surface with a transparent substrate via an ultraviolet-curable silicone adhesive composition. [Solution] An optical laminate having a hard coat layer, wherein the hard coat layer is a cured film of a composition containing at least one epoxy group or oxetanyl group-containing compound, the hard coat layer is laminated with a first transparent substrate via an optical adhesive, and the optical adhesive is a cured film of an ultraviolet-curable silicone adhesive composition.

Description

[Technical Field]

[0001] The present invention relates to an optical laminate, and more particularly to an optical laminate equipped with a polarizer. [Background technology]

[0002] In recent years, the applications of various liquid crystal display devices have expanded beyond mobile devices such as mobile phones and tablet terminals to include in-vehicle image display devices such as car navigation systems and rearview monitors. Consequently, these image display devices are required to have higher durability in harsher environments (for example, high-temperature environments) than previously required.

[0003] Polarizing plates are useful as optical components in liquid crystal display devices and organic light-emitting diode (EL) display devices. Polarizing plates typically consist of transparent substrates laminated on both sides of a polarizer via an adhesive or bonding layer.

[0004] To protect the surface of an image display device, a transparent substrate such as a glass plate or a transparent resin plate is generally laminated onto a polarizing plate via an adhesive. However, the adhesive requires high durability. Therefore, an ultraviolet addition-curing type silicone adhesive composition has been proposed that utilizes a hydrosilylation reaction with an ultraviolet-activated platinum catalyst to cure the resin composition (Patent Document 1). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-055945 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, when manufacturing an image display device by laminating a polarizing plate having a hard coat layer on its surface with a transparent substrate such as a glass plate or a transparent resin plate via an ultraviolet-curable silicone adhesive composition, there were cases where the curing of the ultraviolet-curable silicone adhesive composition was insufficient.

[0007] The present invention aims to provide an optical laminate and an image display device that can sufficiently cure an ultraviolet-curable silicone adhesive composition within a certain time, even when laminating a polarizing plate having a hard coat layer on its surface and a transparent substrate via an ultraviolet-curable silicone adhesive composition. [Means for solving the problem]

[0008] As a result of diligent research to solve the aforementioned problems, the inventors of the present invention have discovered that by making the hard coat layer a cured film of a composition containing at least one epoxy group or oxetanyl group compound, the UV-curable silicone adhesive composition can be sufficiently cured within a certain period of time, and have completed the present invention.

[0009] The present invention provides an optical laminate and an image display device as illustrated below. [1] An optical laminate having a hard coat layer, wherein the hard coat layer is a cured film of a composition containing at least one epoxy group or oxetanyl group-containing compound, the hard coat layer is laminated with a first transparent substrate via an optical adhesive, and the optical adhesive is a cured film of an ultraviolet-curable silicone adhesive composition. [2] The optical laminate according to [1], wherein the epoxy group or oxetanyl group-containing compound is a compound having two or more epoxy groups or oxetanyl groups in one molecule. [3] The optical laminate according to [1], wherein polarizers are laminated on at least one surface. [4] The optical laminate according to [1], wherein the first transparent substrate is a glass plate, a transparent resin plate, or a touch panel. [5] An optical laminate further comprising a second transparent substrate, wherein the hard coat layer is laminated on the second transparent substrate, and the second transparent substrate is any one of triacetyl cellulose, polyethylene naphthalate, polyethylene terephthalate, cycloolefin polymer, polycarbonate, polyacrylate, polyimide and polyamide, the optical laminate according to [1]. [6] An image display device comprising the optical laminate according to any one of [1] to [5].

Advantages of the Invention

[0010] According to the present invention, it is possible to provide an optical laminate and an image display device capable of sufficiently curing an ultraviolet addition-curable silicone adhesive composition within a certain period of time even when a polarizing plate having a hard coat layer on its surface and a transparent member are adhered and laminated with the ultraviolet addition-curable silicone adhesive composition.

Brief Description of the Drawings

[0011] [Figure 1] It is a schematic cross-sectional view showing an example of the layer structure of the optical laminate. [Figure 2] It is a schematic cross-sectional view showing an example of the layer structure of the optical laminate. [Figure 3] It is a schematic cross-sectional view showing an example of the layer structure of the optical laminate.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In all the following drawings, the scales are appropriately adjusted for easy understanding of each component, and the scales of each component shown in the drawings do not necessarily match the scales of the actual components.

[0013] <Optical Laminate> The optical laminate of the present invention comprises a first transparent substrate, a hard coat layer, and an optical adhesive, wherein the hard coat layer is a cured film of a composition containing at least one epoxy group or oxetanyl group-containing compound, and the hard coat layer is laminated with the first transparent substrate via the optical adhesive, and the optical adhesive is a cured film of a curable silicone composition. The optical laminate of the present invention will be described below with reference to the drawings. The optical laminate 10 shown in Figure 1 comprises a first transparent substrate 11, a hard coat layer 12, and an optical adhesive 13. The optical laminate 10 may further include other layers other than those described above, such as a polarizer, an adhesive layer, a second transparent substrate, an optical functional layer, and a protective film. The optical laminate shown in Figure 2 further comprises two second transparent substrates 14, an adhesive layer 15, a polarizer 16, and an adhesive layer 17. The first transparent substrate and the second transparent substrate may be used as optical functional layers, or as circular polarizers. Furthermore, as shown in Figure 3, the optical laminate may have a configuration in which a hard coat layer 12 and an adhesive layer 17 are laminated adjacent to a polarizer 16.

[0014] <Polarizer> The polarizer according to the present invention is a uniaxially stretched polyvinyl alcohol-based resin film on which a dichroic dye is adsorbed and oriented. The polyvinyl alcohol-based resin constituting the polarizer is obtained by saponifying a polyvinyl acetate-based resin. Examples of polyvinyl acetate-based resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. The degree of saponification of the polyvinyl alcohol-based resin is usually 85 to 100 mol%, preferably in the range of 98 to 100 mol%. This polyvinyl alcohol-based resin may be further modified; for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can also be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 to 10,000, preferably in the range of 1,500 to 10,000.

[0015] Polarizers are manufactured by a process of uniaxially stretching a polyvinyl alcohol-based resin film, dyeing the polyvinyl alcohol-based resin film with a dichroic dye and adsorbing the dichroic dye, treating the polyvinyl alcohol-based resin film with the adsorbed dichroic dye with an aqueous boric acid solution, and washing with water after treatment with the aqueous boric acid solution. Alternatively, they may be manufactured by laminating a transparent substrate, a thermoplastic resin film, or an optical functional layer onto a uniaxially stretched polyvinyl alcohol-based resin film that has undergone these processes and has been oriented with the adsorbed dichroic dye.

[0016] Uniaxial stretching may be performed before, simultaneously with, or after staining with dichroic dyes. If uniaxial stretching is performed after staining with dichroic dyes, it may be performed before or during boric acid treatment. Of course, it is also possible to perform uniaxial stretching at multiple stages. Uniaxial stretching may be performed uniaxially between rolls with different peripheral speeds, or using heated rolls. Furthermore, it may be dry stretching performed in the atmosphere, or wet stretching performed in a swollen state with a solvent. The stretching ratio is usually around 4 to 8 times.

[0017] To dye a polyvinyl alcohol-based resin film with a dichroic dye, for example, the polyvinyl alcohol-based resin film can be immersed in an aqueous solution containing the dichroic dye. Specifically, iodine or dichroic dyes can be used as the dichroic dye.

[0018] When iodine is used as a dichroic dye, a dyeing method is typically employed in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing iodine and potassium iodide. The iodine content in this aqueous solution is usually about 0.01 to 0.5 parts by weight per 100 parts by weight of water, and the potassium iodide content is usually about 0.5 to 10 parts by weight per 100 parts by weight of water. The temperature of this aqueous solution is usually about 20 to 40°C, and the immersion time in this aqueous solution is usually about 30 to 300 seconds.

[0019] On the other hand, when using dichroic dyes as dichroic pigments, a method is usually employed in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing a water-soluble dichroic dye. The content of the dichroic dye in this aqueous solution is usually 1 × 10⁻¹⁶ per 100 parts by weight of water. -3 ~1 × 10 -2 The amount is approximately parts by weight. This aqueous solution may contain inorganic salts such as sodium sulfate. The temperature of this aqueous solution is usually around 20 to 80°C, and the immersion time in this aqueous solution is usually around 30 to 300 seconds.

[0020] The boric acid treatment after dyeing with a dichroic dye is performed by immersing the dyed polyvinyl alcohol-based resin film in an aqueous boric acid solution. The boric acid content in the aqueous boric acid solution is usually about 2 to 15 parts by weight, preferably about 3 to 8 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye, it is preferable that the aqueous boric acid solution contains potassium iodide. The potassium iodide content in the aqueous boric acid solution is usually about 2 to 20 parts by weight, preferably about 5 to 15 parts by weight, per 100 parts by weight of water. The immersion time in the aqueous boric acid solution is usually about 100 to 1200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the aqueous boric acid solution is usually 50°C or higher, preferably 50 to 85°C.

[0021] Polyvinyl alcohol-based resin films treated with boric acid are typically subjected to a water washing process. This washing process is carried out, for example, by immersing the boric acid-treated polyvinyl alcohol-based resin film in water. After washing, the film is dried to obtain a polarizer. The water temperature during the washing process is typically around 5 to 40°C, and the immersion time is typically around 2 to 120 seconds. The subsequent drying process is usually carried out using a hot air dryer or far-infrared heater. The drying temperature is typically around 40 to 100°C. The drying time is typically around 120 to 600 seconds.

[0022] Thus, a polarizer is obtained, which consists of a polyvinyl alcohol-based resin film on which iodine or a dichroic dye is adsorbed and oriented. If necessary, this polarizer is laminated with a transparent substrate, a thermoplastic resin film, or an optical functional layer on one or both sides using an adhesive.

[0023] <Hard coat layer> The hard coat layer 12 may have the function of improving scratch resistance. If the optical laminate has two or more hard coat layers, the hard coat layers may be arranged to constitute the outermost surfaces on both sides of the optical laminate 10.

[0024] The hard coat layer 12 is a cured film of a composition containing at least one epoxy group or oxetanyl group-containing compound. As a result of the inventors' studies, it was found that by including an epoxy group or oxetanyl group-containing compound in the hard coat layer 12, the UV-curable silicone adhesive composition can be sufficiently cured even when the hard coat layer and the first transparent substrate 11 are laminated with an optical adhesive 13 made of an UV-curable silicone adhesive composition.

[0025] The epoxy group or oxetanyl group-containing compound has at least one type of reactive group capable of ring-opening polymerization. From the viewpoint of improving scratch resistance, the cured product of the epoxy group or oxetanyl group-containing compound is preferably a cured layer using a compound having two or more epoxy groups or oxetanyl groups in one molecule. Furthermore, since cured products by ring-opening polymerization shrink less than cured products by addition polymerization, curling can be suppressed by adding an epoxy group or oxetanyl group-containing compound.

[0026] The proportion of epoxy group or oxetanyl group-containing compound in the hard coat layer-forming composition is preferably 10% to 99% by mass, more preferably 30% to 99.9% by mass, and even more preferably 50% to 99.9% by mass. If the proportion of epoxy group or oxetanyl group-containing compound is less than 10% by mass, it is undesirable because the UV-curable silicone adhesive composition used as an optical adhesive cannot be sufficiently cured.

[0027] As epoxy group-containing compounds, compounds having alicyclic epoxy groups can be used, for example, 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl3,4-epoxy-6-methylcyclohexanecarboxylate, ethylenebis(3,4-epoxycyclohexanecarboxylate), bis(3,4-epoxycyclohexylmethyl) adipate, bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, diethylene glycol bis(3,4-epoxycyclohexylmethyl ether), ethylene glycol bis(3,4 Examples of compounds that can be used include (-epoxycyclohexylmethyl ether), 2,3,14,15-diepoxy-7,11,18,21-tetraoxatrispiro<5.2.2.5.2.2>henicosane, 3-(3,4-epoxycyclohexyl)-8,9-epoxy-1,5-dioxaspiro<5.5>undecane, bis(2,3-epoxycyclopentyl) ether, dicyclopentadiene dioxide, ε-caprolactone-modified-3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and butanetetracarboxylic acid-tetra(3,4-epoxycyclohexylmethyl)-modified ε-caprolactone. These compounds exhibit rapid cationic polymerization and are suitable for processability of the hard coat layer.

[0028] Furthermore, in the present invention, compounds containing epoxy groups other than alicyclic epoxy groups may be used, for example, methyl glycidyl ether, ethyl glycidyl ether, n-butyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, 1,2-epoxyhexane, 1,2-epoxyoctane, 1,2-epoxydecane, 1,2-epoxydodecane, 1,2-epoxytetradecane, 1,2-epoxyhexadecane, 1,2-epoxyoctadecane, glycidyl methacrylate, phenyl glycidyl ether, 2-phenylphenol glycidyl ether, phenol(EO)5 glycidyl ether, p-tert-butylphenyl glycidyl ether, Examples include N-glycidylphthalimide, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,4-butanediol diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, diglycidyl phthalate ester, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, and polyglycerol polyglycidyl ether. These compounds can be used as appropriate to adjust the viscosity and scratch resistance of hard coat layer forming compositions.

[0029] Examples of compounds containing an oxetanyl group include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis[{(3-ethyloxetan-3-yl)methoxy}methyl]benzene (also called xylylenebisoxetane), 3-ethyl-3-(phenoxymethyl)oxetane, bis(3-ethyloxetan-3-ylmethyl)ether, 2-ethylhexyloxetane, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, 3-ethyl-3-[{(3-triethoxysilyl)propoxy}methyl]oxetane, oxetanylsilsesquioxane, and phenol novolac oxetane. Here, oxetanylsilsesquioxane refers to a silane compound having an oxetanyl group, such as a network-like polysiloxane compound having multiple oxetanyl groups, obtained by hydrolysis and condensation of the above-mentioned 3-ethyl-3-[{(3-triethoxysilyl)propoxy}methyl]oxetane.

[0030] The hard coat layer forming composition may contain components other than the epoxy group or oxetanyl group-containing compounds mentioned above. Examples of other components that may be included include photocationic polymerization initiators, photosensitizers, photosensitizing aids, thermal cationic polymerization initiators, chain transfer agents, thermoplastic resins, flow regulators, defoamers, leveling agents, organic solvents, plasticizers, ultraviolet absorbers, infrared absorbers, colorants such as pigments and dyes, fluorescent whitening agents, dispersants, heat stabilizers, light stabilizers, antistatic agents, antioxidants, lubricants, and various metal oxide fine particles such as silica, alumina, titania, zirconia, calcium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide.

[0031] From the viewpoint of processability, a method of curing a hard coat layer-forming composition by cationic polymerization using active energy rays is preferred. When curing a hard coat layer-forming composition by cationic polymerization irradiated with active energy rays, it is necessary to add a photocationic polymerization initiator to the hard coat layer-forming composition. A photocationic polymerization initiator generates cationic species or Lewis acids upon irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, or electron beams, and initiates the polymerization reaction of epoxy group or oxetanyl group-containing compounds, which are photocationically curable components. Since photocationic polymerization initiators act catalytically with light, they have excellent storage stability and workability even when mixed with photocationically curable components. Examples of compounds that generate cationic species or Lewis acids upon irradiation with active energy rays include onium salts such as aromatic iodonium salts and aromatic sulfonium salts, aromatic diazonium salts, and iron-arene complexes.

[0032] Aromatic iodonium salts are compounds containing diaryliodonium cations, typically including diphenyliodonium cations. Aromatic sulfonium salts are compounds containing triarylsulfonium cations, typically including triphenylsulfonium cations and 4,4′-bis(diphenylsulfonio)diphenylsulfide cations. Aromatic diazonium salts are compounds containing diazonium cations, typically including benzenediazonium cations. Iron-arene complexes are typically cyclopentadienyl iron(II)arene cation complex salts.

[0033] The cations shown above, when paired with anions, constitute photocationic polymerization initiators. An example of an anion that constitutes a photocationic polymerization initiator is the hexafluorophosphate anion PF6. - , trifluorotris(pentafluoroethyl)phosphate anion PF3(C2F5)3 -, hexafluoroantimonate anion SbF6 - , pentafluoro-hydroxyantimonate anion SbF5(OH) - , hexafluoroarsenate anion AsF6 - , tetrafluoroborate anion BF4 - , tetrakis(pentafluorophenyl)borate anion B(C6F5)4 - and so on.

[0034] Among these photo cationic polymerization initiators, particularly aromatic iodonium salts are preferably used because they have ultraviolet absorption characteristics in the wavelength region of 300 nm or less and are less likely to color the cured layer.

[0035] The blending ratio of the photo cationic polymerization initiator is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.3% by mass or more and 5% by mass or less, and even more preferably 0.5% by mass or more and 2% by mass or less in the solid content of the composition for forming the hard coat layer. When the blending ratio of the photo cationic polymerization initiator is less than 0.1% by mass, the composition for forming the hard coat layer is not sufficiently cured, which is not preferable. Also, when the blending ratio of the photo cationic polymerization initiator is more than 10% by mass, the optical laminate of the present invention may be deteriorated due to the influence of the generated acid, which is not preferable.

[0036] The cured layer of the composition for forming the hard coat can be formed by applying the composition for forming the hard coat layer on a polarizer or a second transparent substrate and curing it by light irradiation. The second transparent substrate provided with the hard coat layer 12 can also be bonded to the polarizer 16 through an adhesive layer.

[0037] The thickness of the hard coat layer 12 may be, for example, 20 μm or less, preferably 15 μm or less, and more preferably 10 μm or less. Also, the thickness of the hard coat layer is usually 0.5 μm or more. <The first transparent substrate> Examples of the first transparent substrate 11 include a front panel (window layer) and a touch panel. The front panel should have appropriate mechanical strength and thickness. Examples of such front panels include transparent resin plates such as polyimide resin, acrylic resin, or polycarbonate resin, or glass plates. Functional layers, such as an anti-reflective layer, may be laminated on the viewing side of the front panel. Furthermore, if the front panel is a transparent resin plate, a hard coat layer may be laminated to increase physical strength, or a low-moisture-permeability layer may be laminated to reduce moisture permeability. As for the touch panel, various types of touch panels such as resistive, capacitive, optical, and ultrasonic touch panels, or glass plates and transparent resin plates equipped with touch sensor functions, can be used. When a capacitive touch panel is used as the transparent component, it is preferable to provide a front panel made of glass or a transparent resin plate further on the viewing side than the touch panel. The first transparent substrate 11 can also be a light-transmitting (preferably optically transparent) thermoplastic resin film used in the second transparent substrate 14 described later.

[0038] <Second transparent substrate> The second transparent substrate 14 can function as a protective film to protect the surface of the polarizer 16 and as a base film to support the hard coat layer. When two of the second transparent substrates are used, they can be laminated on the polarizer via the hard coat layer 12 and the adhesive layer 15, for example, as shown in Figure 2.

[0039] The transparent substrate 14 of the second adhesive layer is not particularly limited, but can be a film made of a light-transmitting (preferably optically transparent) thermoplastic resin, such as a polyolefin resin like a chain polyolefin resin (polypropylene resin, etc.) or a cyclic polyolefin resin (norbornene resin, etc.), a cellulose resin like triacetylcellulose or diacetylcellulose, a polyester resin like polyethylene terephthalate or polybutylene terephthalate, a polycarbonate resin, a (meth)acrylic resin like methyl methacrylate resin, a polystyrene resin, a polyvinyl chloride resin, an acrylonitrile-butadiene-styrene resin, an acrylonitrile-styrene resin, a polyvinyl acetate resin, a polyvinylidene chloride resin, a polyamide resin, a polyacetal resin, a modified polyphenylene ether resin, a polysulfone resin, a polyethersulfone resin, a polyarylate resin, a polyamide-imide resin, a polyimide resin, a maleimide resin, etc. In particular, it is preferable to use a film containing at least one selected from the group consisting of cellulose resins, cyclic polyolefin resins, (meth)acrylic resins, polystyrene resins, and maleimide resins.

[0040] These resins can be used individually or in combination of two or more types. Furthermore, these resins can be used after undergoing any appropriate polymer modification, such as copolymerization, crosslinking, molecular end modification, stereoregularity control, and mixing, including reactions between different polymers.

[0041] Cellulosic resins can be organic acid esters or mixed organic acid esters of cellulose in which some or all of the hydrogen atoms in the hydroxyl groups of cellulose are substituted with acetyl groups, propionyl groups, and / or butyryl groups. Examples include those consisting of cellulose acetate esters, propionic acid esters, butyric acid esters, and mixed esters thereof. Among these, triacetylcellulose, diacetylcellulose, cellulose acetate propionate, and cellulose acetate butyrate are preferred.

[0042] These resins may contain appropriate additives, provided that they do not impair transparency. Examples of additives include antioxidants, UV absorbers, antistatic agents, lubricants, nucleating agents, antifogging agents, antiblocking agents, phase difference reducers, stabilizers, processing aids, plasticizers, impact-resistant aids, matting agents, antibacterial agents, and antifungal agents. Multiple types of these additives may be used in combination.

[0043] The thickness of the second transparent substrate 14 is usually 1 μm or more and 100 μm or less, but from the viewpoint of strength and handling, it is preferably 5 μm or more and 85 μm or less, more preferably 10 μm or more and 70 μm or less, and even more preferably 15 μm or more and 50 μm or less.

[0044] The second transparent substrate 14 may also have other optical functions and may be formed in a laminated structure with multiple layers stacked on top of each other. From the viewpoint of optical properties, a thin protective film thickness is preferable, but if it is too thin, the strength will decrease and the processability will be poor. An appropriate film thickness is 5 μm to 100 μm, preferably 10 μm to 80 μm, and more preferably 15 μm to 70 μm.

[0045] In the case of a configuration in which the polarizer 16 has a second transparent substrate on both sides, when bonding using a water-based adhesive such as PVA adhesive, it is preferable that at least one of the protective films be either a cellulose acylate film or a (meth)acrylic resin film in terms of moisture permeability, and among these, a cellulose acylate film is preferred.

[0046] In the configuration where the polarizer 16 has a second transparent substrate on both sides, the type of the second transparent substrate may be the same or different. When the polarizer 16 has a second transparent substrate on both sides, the second transparent substrate with a hard coat layer can be arranged such that the hard coat layer constitutes the outermost surface on both sides of the second transparent substrate. The second transparent substrate may have a surface treatment layer (coating layer), such as an antistatic layer, on its outer surface (the surface opposite to the polarizer 16). The thickness of the second transparent substrate includes the thickness of the surface treatment layer.

[0047] The second transparent substrate 14 may have a phase difference function for purposes such as viewing angle compensation. In this case, the film itself may have the phase difference function, or it may have a separate phase difference layer, or a combination of both. The film having the phase difference function may be laminated to the polarizer 16 via another second transparent substrate and an adhesive layer.

[0048] (adhesive layer) The adhesive layer can be used, for example, to bond a second transparent substrate 14 to a polarizer 16. Any suitable adhesive can be used to constitute the adhesive layer. The adhesive can be a water-based adhesive, a solvent-based adhesive, a photocurable adhesive, etc., but a water-based adhesive is preferred.

[0049] The thickness of the adhesive during application can be set to any appropriate value. For example, it can be set so that an adhesive layer of the desired thickness is obtained after curing or heating (drying). The thickness of the adhesive layer is preferably 0.01 μm to 7 μm, more preferably 0.01 μm to 5 μm, even more preferably 0.01 μm to 2 μm, and most preferably 0.01 μm to 1 μm.

[0050] (Water-based adhesive) Any suitable water-based adhesive can be used. Among these, water-based adhesives containing PVA resin (PVA adhesives) are preferred. From the viewpoint of adhesive properties, the average degree of polymerization of the PVA resin contained in the water-based adhesive is preferably about 100 to 5500, and more preferably about 1000 to 4500. From the viewpoint of adhesive properties, the average degree of saponification is preferably about 85 mol% to 100 mol%, and more preferably about 90 mol% to 100 mol%.

[0051] The PVA resin included in the above-mentioned water-based adhesive is preferably one containing acetoacetyl groups, because it exhibits excellent adhesion between the PVA resin layer and the protective film, as well as superior durability. The acetoacetyl group-containing PVA resin can be obtained, for example, by reacting a PVA resin with diketene in any way. The degree of acetoacetyl group modification in the acetoacetyl group-containing PVA resin is typically 0.1 mol% or more, and preferably around 0.1 mol% to 20 mol%. The resin concentration of the above-mentioned water-based adhesive is preferably 0.1% by mass or more and 15% by mass or less, and more preferably 0.5% by mass or more and 10% by mass or less.

[0052] Water-based adhesives can also contain crosslinking agents. Known crosslinking agents can be used. This is possible. Examples include water-soluble epoxy compounds, dialdehydes, and isocyanates.

[0053] If the PVA resin is an acetoacetyl group-containing PVA resin, the crosslinking agent is preferably one of glyoxal, glyoxylate, or methylolmelamine, preferably glyoxal or glyoxylate, and particularly preferably glyoxal.

[0054] Water-based adhesives may also contain organic solvents. Alcohols are preferred as the organic solvent because they are miscible with water, and methanol or ethanol are more preferred among alcohols.

[0055] The methanol concentration in the water-based adhesive is preferably 10% by mass or more and 70% by mass or less, more preferably 15% by mass or more and 60% by mass or less, and even more preferably 20% by mass or more and 60% by mass or less. A methanol concentration of 10% by mass or more makes it easier to suppress polyene formation in high-temperature environments. Furthermore, a methanol content of 70% by mass or less can suppress deterioration of hue.

[0056] (Photocuring adhesive) Photocurable adhesives are adhesives that harden when irradiated with light such as ultraviolet light. Examples include adhesives containing polymerizable compounds and photopolymerization initiators, adhesives containing photoreactive resins, and adhesives containing binder resins and photoreactive crosslinking agents. Examples of polymerizable compounds include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, and oligomers derived from these monomers. Examples of photopolymerization initiators include compounds containing substances that generate active species such as neutral radicals, anionic radicals, and cationic radicals when irradiated with ultraviolet light or the like.

[0057] (Adhesive layer) The adhesive layer can be used, for example, for laminating the phase difference film described later. The adhesive layer can be composed of an adhesive composition mainly composed of resins such as (meth)acrylic resin, rubber resin, urethane resin, ester resin, silicone resin, and polyvinyl ether resin. Among these, an adhesive composition using (meth)acrylic resin as the base polymer, which has excellent transparency, weather resistance, and heat resistance, is preferred. The adhesive composition may be photocurable or thermocurable. The thickness of the adhesive layer is usually 3 μm to 30 μm, preferably 3 μm to 25 μm.

[0058] As the (meth)acrylic resin (base polymer) used in the adhesive composition, polymers or copolymers using one or more (meth)acrylic acid esters as monomers, such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, are preferably used. It is preferable to copolymerize polar monomers into the base polymer. Examples of polar monomers include monomers having carboxyl groups, hydroxyl groups, amide groups, amino groups, epoxy groups, etc., such as (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate.

[0059] The adhesive composition may contain only the base polymer described above, but it usually further contains a crosslinking agent. Examples of crosslinking agents include divalent or higher metal ions that form metal carboxylate salts with carboxyl groups, polyamine compounds that form amide bonds with carboxyl groups, polyepoxy compounds and polyols that form ester bonds with carboxyl groups, and polyisocyanate compounds that form amide bonds with carboxyl groups. Among these, polyisocyanate compounds are preferred.

[0060] The thickness of the adhesive layer is preferably 1 μm to 200 μm, more preferably 2 μm to 100 μm, even more preferably 2 μm to 80 μm, and particularly preferably 3 μm to 50 μm.

[0061] <Optical functional layer> The optical functional layer can be, for example, a phase difference layer. Examples of phase difference layers include a layer that provides a phase difference of λ / 2, a layer that provides a phase difference of λ / 4 (positive A plate), and a positive C plate. The optical functional layer may include an alignment layer and a substrate, and may have two or more liquid crystal layers, alignment layers, and substrates. If the polarizer has a film that provides a phase difference of λ / 4 with the polarizing element, the polarizer can be a circular polarizer. The first transparent substrate 11 and the second transparent substrate 14 can also serve as phase difference layers, but the phase difference layer can also be laminated separately from these films. In the latter case, the phase difference layer can be laminated to the polarizer via an adhesive layer or a bonding agent layer.

[0062] Examples of the phase difference layer include a birefringent film composed of a stretched film of a translucent thermoplastic resin, and the above-mentioned liquid crystal layer formed on a base film. The base film is usually a film made of a thermoplastic resin, and an example of a thermoplastic resin is a cellulose ester resin such as triacetylcellulose.

[0063] Other examples of optical functional layers include light-gathering plates, brightness-enhancing films, reflective layers (reflective films), semi-transparent reflective layers (semi-transparent reflective films), light-diffusing layers (light-diffusing films), and anti-reflective films.

[0064] <Protective film> The optical laminate 10 can be made into an optical laminate with a protective film by laminating a protective film to protect its surface (typically the polarizer, hard coat layer, first transparent substrate, and second transparent substrate). The protective film is peeled off along with its adhesive layer after the optical laminate 10 has been bonded to, for example, an image display element or other optical component.

[0065] The protective film is composed of, for example, a base film and an adhesive layer laminated thereon. The adhesive layer is described above. The resin constituting the base film can be a thermoplastic resin such as polyethylene, polypropylene, polyester, or polycarbonate. Preferably, it is a polyester resin such as polyethylene terephthalate.

[0066] The thickness of the protective film is not particularly limited, but it is preferably in the range of 20 μm to 200 μm. When the thickness of the substrate is 20 μm or more, the optical laminate 10 tends to be more easily given strength.

[0067] <Method for manufacturing optical laminates> One method for manufacturing the optical laminate 10 is to form a hard coat layer 12 on a second transparent substrate 14, then bond the polarizer 16 to the side of the second transparent substrate 14 opposite to the hard coat layer 12 via an adhesive layer, and finally bond it to the first transparent substrate 11 using an optical adhesive 13. Alternatively, one method is to form the hard coat layer 12 on the polarizer 16 and then bond it to the first transparent substrate 11 using an optical adhesive 13.

[0068] <Optical adhesive> The optical adhesive 13 can have the function of bonding the optical laminate 10 and the first transparent substrate 11. The optical adhesive 13 may be light-transmitting, and is preferably optically transparent.

[0069] The thickness of the optical adhesive 13 may be, for example, 10 μm or more and 1000 μm or less, preferably 15 μm or more and 800 μm or less, more preferably 20 μm or more and 700 μm or less, and even more preferably 25 μm or more and 600 μm or less.

[0070] The optical adhesive 13 can be formed from an ultraviolet-curable silicone adhesive composition. The ultraviolet-curable silicone adhesive composition does not harden immediately after irradiation with ultraviolet light, but the hardening reaction gradually begins after irradiation with ultraviolet light, making it easier to bond and fix components together between the irradiation with ultraviolet light and the hardening period. The ultraviolet-curable silicone adhesive composition may be translucent before hardening, and from the viewpoint of hardening properties, it is preferably colorless and transparent before hardening, and more preferably colorless and transparent both before and after hardening.

[0071] The curing time of the UV-curable silicone adhesive composition may be, for example, 1 minute to 24 hours in an atmospheric environment at a temperature of 20°C to 80°C.

[0072] The UV-curable silicone adhesive composition may be, for example, a composition containing a silicone polymer having alkenyl groups, a silicone polymer having H groups, and a photoactivating catalyst, and can be cured by a hydrosilylation reaction between the silicone polymer having alkenyl groups and the silicone polymer having H groups upon UV irradiation.

[0073] The alkenyl group is preferably one having 2 to 10 carbon atoms, and more preferably 2 to 6. Specifically, examples include vinyl, allyl, butenyl, pentenyl, and hexenyl groups, with vinyl being particularly preferred.

[0074] A silicone polymer having an alkenyl group may also have at least one of a monovalent saturated hydrocarbon group and an aryl group in addition to the alkenyl group.

[0075] The monovalent saturated hydrocarbon group is preferably one having 1 to 12 carbon atoms, and more preferably 1 to 6. Specifically, it may be linear, branched, or cyclic, and examples include unsubstituted or substituted monovalent saturated hydrocarbon groups such as linear or branched alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, cycloalkyl groups such as cyclohexyl group, and halogenated alkyl groups such as chloromethyl group, 3-chloropropyl group, and 3,3,3-trifluoropropyl group. Among these, the methyl group is preferred in terms of heat resistance.

[0076] The aryl group is preferably one having 6 to 20 carbon atoms, and more preferably 6 to 10. Specifically, examples include phenyl, naphthyl, tolyl, xylyl, mesityl, and halogen-substituted aryl groups such as chlorophenyl, with phenyl being preferred.

[0077] The H group may be a silicon atom-bonded hydrogen atom <H group in a hydrosilyl group (Si-H group)>. Silicone polymers having an H group may have substituted or unsubstituted monovalent hydrocarbon groups other than aliphatic unsaturated hydrocarbon groups. Examples of substituted or unsubstituted monovalent hydrocarbon groups other than aliphatic unsaturated hydrocarbon groups include those with 1 to 20 carbon atoms, more preferably 1 to 10. The monovalent hydrocarbon group may be linear, branched, or cyclic. Specific examples include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, and n-hexyl groups; cycloalkyl groups such as cyclohexyl groups; aromatic or aromatic group-containing monovalent hydrocarbon groups such as phenyl and tolyl groups; aralkyl groups such as benzyl and phenylethyl groups; halogen-substituted monovalent hydrocarbon groups such as 3,3,3-trifluoropropyl groups; and cyano-substituted monovalent hydrocarbon groups such as cyanoethyl groups. Among these, the methyl group is preferred.

[0078] The silicone polymer having H groups is preferably blended in an amount such that the molar ratio of hydrosilyl groups to alkenyl groups is hydrosilyl groups / alkenyl groups = 0.5 to 2, and more preferably in an amount of 1 to 1.2. Within this range, the composition tends to have excellent curability and the hardness of the resulting cured product.

[0079] Examples of photoactivatable catalysts include platinum group metal catalysts (hereinafter also referred to as platinum group metal catalysts for simplicity) that are activated by light with a wavelength of 200 to 500 nm. Platinum group metal catalysts are inert under light shielding and, upon irradiation with light with a wavelength of 200 to 500 nm, transform into active platinum group metal catalysts at room temperature. These catalysts promote the hydrosilylation reaction between alkenyl groups in a silicone polymer having alkenyl groups and silicon-bonded hydrogen atoms in a silicone polymer having H groups.

[0080] As a specific example of a platinum group metal catalyst, (η 5 Examples include trialiphatic platinum compounds (-cyclopentadienyl) and their derivatives. Particularly preferred are cyclopentadienyltrimethylplatinum, methylcyclopentadienyltrimethylplatinum, and derivatives thereof modified with the cyclopentadienyl group. Bis(β-diketonato)platinum compounds can also be used, preferably bis(acetylacetonato)platinum compounds and derivatives thereof modified with the acetylacetonato group.

[0081] The amount of platinum group metal catalyst in the UV addition-curing silicone adhesive composition is not limited as long as it promotes the curing (hydrosilylation reaction) of the composition. The amount of platinum group metal atoms in the composition may be, for example, 0.01 ppm to 500 ppm by mass, preferably 0.05 to 100 ppm, and more preferably 0.01 to 50 ppm, relative to the total mass of the silicone polymer having alkenyl groups and the silicone polymer having H groups.

[0082] The UV-curing silicone adhesive composition may further contain adhesive aids, reaction regulators, thixotropic regulators such as fumed silica, reinforcing agents such as crystalline silica, antioxidants, light stabilizers, heat-resistant improvers such as metal oxides and metal hydroxides, colorants such as titanium dioxide, thermal conductivity-imparting fillers such as alumina and crystalline silica, viscosity modifiers such as non-reactive silicone oils without reactive functional groups, conductivity imparting agents such as metal powders such as silver and gold, pigments, dyes for coloring, etc.

[0083] Examples of adhesive aids include organic compounds containing at least one functional group from the group consisting of (meth)acrylic, carbonyl, epoxy, alkoxysilyl, and amide groups in one molecule. Specific examples of adhesive aids containing alkoxysilyl groups include γ-(glycidoxypropyl)trimethoxysilane (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.), γ-(methacryloxypropyl)trimethoxysilane (trade name: KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.), and their hydrolysis condensates. Specific examples of compounds containing at least one of the above functional groups and an organosiloxane skeleton include those represented by the following structural formula. [ka] (In the formula, Me represents a methyl group.)

[0084] Furthermore, specific examples of adhesive aids that do not contain an organosiloxane skeleton include allyl glycidyl ether, vinylcyclohexene monooxide, diethyl 2-allylmalonate, allyl benzoate, diallyl phthalate, tetraallyl pyromellitic acid, and triallyl isocyanurate.

[0085] Specific examples of reaction control agents include 3-methyl-1-buty-3-ol, 3-methyl-1-pentin-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynylcyclohexanol, ethinylmethyldecylcarbinol, 3-methyl-3-trimethylsiloxy-1-butyne, 3-methyl-3-trimethylsiloxy-1-pentine, 3,5-dimethyl-3-trimethylsiloxy-1-hexyn, and 1-ethynyl methyl 3-butyne. Examples include nyl-1-trimethylsiloxycyclohexane, bis(2,2-dimethyl-3-butinoxy)dimethylsilane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, and 11,3,3-tetramethyl-1,3-divinyldisiloxane, with 1-ethynylcyclohexanol, ethinylmethyldecylcarbinol, and 3-methyl-1-butyne-3-ol being preferred.

[0086] For example, UV-curable silicone adhesive compositions described in Japanese Patent Publication No. 2020-055945 and Japanese Patent Publication No. 2020-117654 can be used. Alternatively, commercially available UV-curable silicone adhesive compositions can be used. Examples of commercially available UV-curable silicone adhesive compositions include KER-4550, KER-4410, KER-4510, KER-4690-A / B, and KER-4691-A / B (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0087] <Method for manufacturing laminates> The method for manufacturing the laminate includes a coating step, an ultraviolet irradiation step, a curing step, and a bonding step, and each step can be carried out using, for example, the methods shown below.

[0088] (A) Coating process In the coating process, the UV-curable silicone adhesive composition can be applied to one of the substrates. The coating method is not particularly limited and examples include coating using a slit coat, the DAM-Fill method, the fishbone method, etc. The DAM-Fill method is a method in which a dam material is provided so as to surround the peripheral area of ​​the image display panel in order to prevent the UV-curable silicone adhesive composition from spreading before curing, a transparent member is placed on the dam material, and the UV-curable silicone adhesive composition is injected. After the injection of the UV-curable silicone adhesive composition, alignment and degassing are performed as necessary, and then curing is performed by irradiation with ultraviolet light.

[0089] The amount of UV-curable silicone adhesive composition applied to the substrate can be such that, after curing, the thickness of the UV-curable silicone adhesive layer is, for example, 10 μm to 1000 μm.

[0090] Before applying the UV-curable silicone adhesive composition, the bonding surface may be activated by known pretreatment steps such as primer treatment, plasma treatment, or excimer light treatment.

[0091] (B) Ultraviolet irradiation process In the ultraviolet irradiation process, ultraviolet light can be irradiated onto the ultraviolet-curable silicone adhesive composition. Methods for ultraviolet irradiation include using a 365nm UV-LED lamp, a metal halide lamp, or the like as an ultraviolet light source to irradiate an appropriate amount of ultraviolet light.

[0092] For ultraviolet irradiation, light with a wavelength of 200-500 nm, more preferably 200-380 nm, is used. In this case, from the viewpoint of curing speed and prevention of discoloration, the irradiation temperature is preferably 20-80°C, and the irradiation intensity is 30-2000 mW / cm². 2 Preferably, the irradiation dose is 150 to 10000 mJ / cm². 2 It is preferable.

[0093] (C) Curing process In the curing process, the UV-curable silicone adhesive composition can be cured by UV irradiation. Curing methods include a method in which the UV-curable silicone adhesive composition, after UV irradiation, is left to cure in a predetermined environment to form a UV-curable silicone adhesive layer. The curing temperature of the UV-curable silicone adhesive composition is not particularly limited, but it is preferable to cure it in an atmospheric environment at 20-80°C for 1 minute to 1 day.

[0094] (D) Lamination process In the bonding process, one substrate is laminated onto the UV-curable silicone adhesive composition or UV-curable silicone adhesive layer to form a laminate in which two substrates are bonded together via the adhesive composition or UV-curable silicone adhesive layer. Bonding methods include placing the UV-curable silicone adhesive layer-substrate laminate, which has become semi-solid from a liquid state after a coating process, UV irradiation process, and curing process, or the adhesive composition after the coating process, or the UV-curable silicone adhesive composition-substrate laminate after both the coating and UV irradiation processes, into a vacuum or atmospheric pressure bonding apparatus, and then laminating the other substrate onto the UV-curable silicone adhesive composition or UV-curable silicone adhesive layer. In the case of the UV-curable silicone adhesive composition, the remaining processes are carried out to cure and form a laminate.

[0095] UV-curing silicone adhesive compositions are not affected by oxygen-induced curing inhibition, and the curing time after UV irradiation can be varied depending on the design of the adhesive composition and the heating temperature. This allows for the free selection and modification of the application process, UV irradiation process, curing process, and bonding process to suit the structure of the device being manufactured, such as flat displays and curved displays.

[0096] Regarding the manufacturing method of the laminate, the manufacturing method of a laminate comprising the polarizing plate and front plate described above will be explained as a specific example. First, an ultraviolet addition-curing silicone adhesive composition is applied to the hard coat layer of the polarizing plate. Then, using a UV-LED lamp whose maximum intensity is around a wavelength of 365 nm, the irradiation intensity is set to 30 to 2000 mW / cm using 365 nm light as the indicator. 2 (For example, 100mW / cm²) 2 ) and doses of 150-10000 mJ / cm² 2 (For example, 3000 mJ / cm 2 The UV-curable silicone adhesive composition is irradiated with ultraviolet light at 20-80°C (e.g., 23°C) for 1 second to 1 hour (e.g., 30 seconds) so that it becomes UV-curable. Subsequently, the UV-curable silicone adhesive composition is cured by letting it stand in an environment of 20-80°C (e.g., 23°C) for 1 minute to 1 day (e.g., 30 minutes) to form a UV-curable silicone adhesive layer. After that, a front plate is laminated on the UV-curable silicone adhesive layer using a vacuum bonding device to obtain a laminate in which the polarizing plate and the front plate are bonded via the UV-curable silicone adhesive layer. Alternatively, after the UV irradiation step, the front plate may be laminated on the UV-curable silicone adhesive composition using a vacuum bonding device to bond the polarizing plate and the front plate via the UV-curable silicone adhesive composition, and then the UV-curable silicone adhesive composition may be cured by letting it stand in an environment of 20-100°C (e.g., 60°C) for 1 minute to 1 day (e.g., 30 minutes). If the front panel is transparent, after the coating process, vacuum bonding may be performed, followed by UV irradiation through the front panel to cure it. Alternatively, a UV-curable silicone adhesive composition that has been pre-irradiated with UV light may be applied to the image display panel, vacuum-bonded to the cover panel, and then cured.

[0097] <Applications of optical laminates> The optical laminate 10 is used in various image display devices such as liquid crystal displays and organic EL displays. An example of an image display device is one having an image display cell, an adhesive layer laminated on the viewing surface of the image display cell, and an optical laminate laminated on the viewing surface of the adhesive layer. The optical laminate of the present invention is suitably used in an image display device having an interlayer-filled structure in which a first transparent substrate is placed on the viewing side of the image display device, and the optical laminate and the image display cell are bonded together by the adhesive layer. Note that the member used to bond the optical laminate and the image display cell is not limited to an adhesive layer, but may also be an adhesive layer.

[0098] <Image display cell> Examples of image display cells include liquid crystal cells and organic EL cells. As for liquid crystal cells, any of the following types may be used: reflective liquid crystal cells that utilize ambient light, transmissive liquid crystal cells that utilize light from a backlight or other light source, and semi-transmissive semi-reflective liquid crystal cells that utilize both external light and light from a light source. When the liquid crystal cell utilizes light from a light source, the image display device (liquid crystal display device) also has a polarizer positioned on the opposite side of the image display cell (liquid crystal cell) from the viewing side, and further a light source is positioned therein. Preferably, the polarizer on the light source side and the liquid crystal cell are bonded together via an appropriate adhesive layer. As for the driving method of the liquid crystal cell, any type can be used, such as VA mode, IPS mode, TN mode, STN mode, or bend orientation (π type).

[0099] As an organic EL cell, a suitable example is one in which a light-emitting body (organic electroluminescent light-emitting body) is formed by sequentially laminating a transparent electrode, an organic light-emitting layer, and a metal electrode on a transparent substrate. The organic light-emitting layer is a laminate of various organic thin films, and various layer configurations can be adopted, such as a laminate of a hole injection layer made of a triphenylamine derivative or the like and a light-emitting layer made of a fluorescent organic solid such as anthracene, a laminate of these light-emitting layers and an electron injection layer made of a perylene derivative or the like, or a laminate of a hole injection layer, a light-emitting layer, and an electron injection layer.

[0100] <Bonding of image display cells and optical laminates> An adhesive layer (adhesive sheet) is preferably used to bond the image display cell to the optical laminate. Among these, the method of bonding the optical laminate having the above-mentioned adhesive layer to the image display cell is preferred from the viewpoint of workability and other factors. Alternatively, an organic solvent dilution of the above-mentioned adhesive composition can be applied to the image display cell to form an adhesive layer, which can then be bonded to the optical laminate. [Examples]

[0101] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" means parts by weight.

[0102] [Preparation of compositions for forming a hard coat layer] The components shown in Table 1 were mixed and stirred in the proportions described in the Examples and Comparative Examples in Table 1 to obtain a composition for forming a hard coat layer.

[0103] [Table 1]

[0104] [Formation of the hard coat layer] On a transparent film substrate (triacetylcellulose resin film, 80 μm thick), the hard coat layer-forming compositions described in the Examples and Comparative Examples of Table 1 were applied using a bar coater with a line count of 8 to a film thickness of approximately 5 μm after drying. The coating was dried in a 70°C oven for 120 seconds. Using an Iwasaki Electric I-Graphics ECS401XN2-1 ultraviolet irradiation conveyor system, high-pressure mercury lamps were used with an output of 3 kW, a line speed of 4 m / min, two UV irradiations, and an irradiation intensity of 148 mW / cm². 2 Total luminous intensity 536 mJ / cm² 2 Under these conditions, ultraviolet light was irradiated onto the coating to form a hard coat layer.

[0105] [Curing test of UV-curable silicone adhesive composition] Approximately 1 ml of Lumisil245 GEL 1K UV, an ultraviolet-curing silicone adhesive composition manufactured by Asahi Kasei Wacker Silicone Co., Ltd., was dropped onto the hard coat layer side of a transparent film substrate with a hard coat layer formed on it. Then, using an ultraviolet irradiation conveyor system ECS401XN2-1 manufactured by Iwasaki Electric I-Graphics Co., Ltd., a metal halide lamp was used to irradiate the film with UV light three times at an output of 4 kW, a line speed of 4 m / min, and an irradiation intensity of 220 mW / cm². 2 Total luminous intensity: 1980 mJ / cm² 2 Under these conditions, ultraviolet light was irradiated onto the coating film, and the curability of the UV-curable silicone adhesive composition was evaluated by touching it with a finger after 30 minutes, according to the following criteria. The results are shown in Table 2. ○: Sufficiently hardened and does not peel off the hard coat layer even when touched with a finger. ×: The hardening is insufficient, and it peels off the hard coat layer when touched with a finger. [Table 2]

[0106] [Saponification of film] A transparent film substrate with a hard coat layer was immersed in a 1.5 mol / L NaOH aqueous solution (saponification solution) maintained at 55°C for 2 minutes, after which the film was rinsed with water. After that, the water was removed by draining with a water-draining nip roll, and then the film was dried in a 70°C drying zone for 15 seconds, followed by saponification treatment.

[0107] [Fabrication of polarizers] Based on Example 1 of Japanese Patent Publication No. 11-218611, dyes 1 to 4 were prepared, and dyes 1 to 4 and Glauber's salt were dissolved in water to create a dyeing solution.

[0108] Dye 1: CIDirect Orange 39 (Kayafect Orange G, manufactured by Nippon Kayaku Co., Ltd.) was used.

[0109] Dye 2: I used CIDirect Red 81 (Red 4BL manufactured by Nippon Chemical Industries, Ltd.).

[0110] Dye 3: A dye with the chemical formula described in Japanese Patent Publication No. 11-218611 was synthesized in accordance with said publication.

[0111] [ka]

[0112] Dye 4: A dye with the chemical formula disclosed in Example 38 of Japanese Patent Publication No. 60-156759 was synthesized in accordance with the said publication.

[0113] [ka]

[0114] Next, a PVA resin film (VF-PS#7500, manufactured by Kuraray Co., Ltd.) was uniaxially stretched while immersed in water to swell, then immersed in the dyeing solution, and stretched with a boric acid aqueous solution to orient the dye within the resin film. The total uniaxial stretching ratio from swelling to boric acid treatment was 4 to 5 times. After stretching, the film was dried in a 70°C dryer for 3 minutes while maintaining tension to form a polarizer. The obtained polarizer exhibited a grayish color, and its optical properties, measured using a Hitachi High-Tech Science Co., Ltd. UH-4150 spectrophotometer, were Ys=60.5%, Py=47.7%, L * a * The hues in the b* color space are, respectively, L * s=82.1, a * s=0.4, and b * s = -0.2.

[0115] [Lamination] A transparent film substrate with a saponified hard coat layer and a transparent film substrate with a saponified hard coat layer were laminated to both sides of the fabricated polarizer via a PVA-based adhesive. The side of the transparent film substrate with the saponified hard coat that did not have a hard coat layer was used as the bonding surface with the polarizer. After lamination, the film was heated and dried at 70°C for 5 minutes to produce a film with transparent substrates laminated on both sides of the polarizer.

[0116] Approximately 1 ml of Lumisil245 GEL 1K UV manufactured by Asahi Kasei Wacker Silicone Co., Ltd. was dropped onto the hard coat layer side of the film prepared as described above, and then a 1 mm thick glass was laminated to it. The laminated sample was then subjected to UV irradiation using a metal halide lamp with an output of 4 kW, a line speed of 4 m / min, 3 UV irradiations, and an integrated light intensity of 1980 mJ / cm² using an Iwasaki Electric I-Graphics Co., Ltd. UV irradiation conveyor system ECS401XN2-1, with an output of 4 kW, a line speed of 4 m / min, and an integrated light intensity of 1980 mJ / cm². 2 Under these conditions, when ultraviolet light was irradiated from the glass surface side, the optical laminate of the present invention could be fabricated using the hard coat layer forming composition described in the example. On the other hand, when the hard coat layer forming composition described in the comparative example was used, curing was insufficient, the glass shifted, and it was not possible to fabricate an optical laminate.

[0117] From the above results, it can be seen that by using the present invention, the UV-curable silicone adhesive composition can be sufficiently cured, and the optical laminate of the present invention can be provided.

Claims

1. An optical laminate characterized by having a hard coat layer, wherein the hard coat layer is a cured film of a composition containing at least one epoxy group or oxetanyl group-containing compound, the hard coat layer is laminated with a first transparent substrate via an optical adhesive, and the optical adhesive is a cured film of an ultraviolet-curable silicone adhesive composition.

2. The optical laminate according to claim 1, wherein the epoxy group or oxetanyl group-containing compound is a compound having two or more epoxy groups or oxetanyl groups in one molecule.

3. The optical laminate according to claim 1, wherein polarizers are laminated on at least one surface.

4. The optical laminate according to claim 1, wherein the first transparent substrate is a glass plate, a transparent resin plate, or a touch panel.

5. The optical laminate according to claim 1, further comprising a second transparent substrate, wherein the hard coat layer is laminated on the second transparent substrate, and the second transparent substrate is any of triacetylcellulose, polyethylene naphthalate, polyethylene terephthalate, cycloolefin polymer, polycarbonate, polyacrylate, polyimide, and polyamide.

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

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