Optical stack

Abstract

To provide an optical laminate which prevents problems in image display functionality of image display devices.SOLUTION: An optical laminate of the present invention comprises an adhesive sheet 1 made of a photocurable composition, and an optical film 2 including at least one selected from a group consisting of a polarizing film and a retardation film. Anchoring force F between the adhesive sheet 1 and the optical film 2 is 10.0 N / 25 mm or greater. The anchoring force F may be greater than 16.0 N / 25 mm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an optical laminate. [Background technology]

[0002] Various image display devices, such as liquid crystal displays and electroluminescent (EL) displays, generally comprise an optical laminate containing optical films, such as polarizing films, and adhesive sheets. Adhesive sheets are typically used for bonding between the optical films contained in the optical laminate and for bonding the optical laminate to the image display panel. Typical adhesive sheets are those cured by polymerization and crosslinking of monomer groups, including acrylic monomers and silicone monomers.

[0003] Patent Document 1 discloses an example of an adhesive sheet. In Patent Document 1, the adhesive sheet is manufactured by irradiating an adhesive composition with light. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 3052972 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Typical adhesive sheets are manufactured, for example, by the following thermosetting method. First, a polymer is produced by polymerizing polymerizable monomers in an organic solvent, and a crosslinking agent is added to the polymer to prepare an adhesive composition. This adhesive composition is applied to a substrate such as a release liner, and the organic solvent is heated and removed to form a sheet. If necessary, heat aging is performed to complete the crosslinking, thereby producing an adhesive sheet. In this manufacturing process, a large amount of fuel such as LNG needs to be burned to generate the thermal energy required for heating and removing the solvent and for heat aging. Furthermore, if the heated organic solvent is released directly into the atmosphere, it may have a significant adverse effect on the surrounding environment. Therefore, the organic solvent is often burned in a deodorizer before being released. In this case, not only is additional fuel required for combustion in the deodorizer, but the organic solvent itself is also converted into CO2 by combustion and released into the atmosphere, making it a manufacturing process with extremely high CO2 emissions.

[0006] In recent years, climate change caused by greenhouse gases has become an urgent issue, and governments around the world are working to reduce CO2 emissions by setting numerical targets. In the manufacturing of adhesive sheets, there is a need to select manufacturing processes that do not use organic solvents and that produce fewer CO2 emissions.

[0007] The method of producing adhesive sheets using light (photocuring method) reduces the amount of energy required for adhesive sheet formation and CO2 emissions compared to the thermocuring method described above. However, when an optical laminate is made using an adhesive sheet formed by the photocuring method, the image display device equipped with the optical laminate tends to experience problems with image display functionality after prolonged use. This problem can be particularly pronounced when the device is repeatedly used in high-temperature environments.

[0008] Therefore, the present invention aims to provide an optical laminate that can suppress problems occurring in the image display function of an image display device. [Means for solving the problem]

[0009] According to the studies by the present inventors, when an adhesive sheet formed by a photocuring method is used, there is a tendency that peeling between the adhesive sheet and an optical film is likely to occur as compared with the case where an adhesive sheet formed by a thermocuring method is used. This tendency is presumably due to the fact that when an adhesive sheet formed by a thermocuring method is bonded to an optical film, curing of the adhesive sheet further proceeds on the surface of the optical film, while in the case of an adhesive sheet formed by a photocuring method, curing hardly proceeds after being bonded to the optical film. This problem can occur particularly significantly when the optical film includes a uniaxially stretched film such as a polarizer or when the thickness of the adhesive sheet is 30 μm or less.

[0010] When peeling occurs between the adhesive sheet and the optical film, not only does air enter therebetween, but the optical film may also be displaced from an appropriate position. Due to these reasons, there is a tendency that problems occur in the image display function of the image display device. Based on the above findings, the present inventors have proceeded with studies and completed the present invention.

[0011] The present invention provides an adhesive sheet formed from a photocurable composition, an optical film including at least one selected from the group consisting of a polarizing film and a retardation film, and provides an optical laminate in which an anchoring force between the adhesive sheet and the optical film is 10.0 N / 25 mm or more.

Advantages of the Invention

[0012] According to the present invention, it is possible to provide an optical laminate capable of suppressing problems from occurring in the image display function of an image display device.

Brief Description of the Drawings

[0013] [Figure 1] It is a cross-sectional view schematically showing an example of the optical laminate of the present invention. [Figure 2A] It is a schematic diagram for explaining a method of measuring the amount of creep with respect to an adhesive sheet. [Figure 2B]This is a schematic diagram illustrating a method for measuring the amount of creep in an adhesive sheet. [Figure 3A] This is a schematic diagram illustrating an example of a method for manufacturing an optical laminate according to the present invention. [Figure 3B] This is a schematic diagram illustrating an example of a method for manufacturing the adhesive sheet of the present invention. [Figure 3C] This is a schematic diagram illustrating an example of a method for manufacturing an optical laminate according to the present invention. [Figure 4] This is a schematic cross-sectional view showing an example of the optical laminate of the present invention. [Modes for carrying out the invention]

[0014] The optical laminate according to the first aspect of the present invention is An adhesive sheet formed from a photocurable composition, An optical film comprising at least one selected from the group consisting of polarizing films and phase difference films, Equipped with, The anchoring force between the adhesive sheet and the optical film is 10.0 N / 25 mm or more.

[0015] In a second aspect of the present invention, for example, in the optical laminate according to the first aspect, the anchoring force is greater than 16.0 N / 25 mm.

[0016] In a third aspect of the present invention, for example, in an optical laminate according to the first or second aspect, the adhesive strength P0 determined by the following test is 8.0 N / 25 mm or less. Test: The adhesive sheet is attached to alkali-free glass, and the adhesive sheet is peeled off the alkali-free glass at a peeling speed of 300 mm / min and a peeling angle of 90°. The force required at this time (adhesive force P0) is measured.

[0017] In a fourth aspect of the present invention, for example, in the optical laminate according to the third aspect, the adhesive force P0 is 0.5 to 7.0 N / 25 mm.

[0018] In a fifth aspect of the present invention, for example, in an optical laminate according to the third or fourth aspect, the difference between the anchoring force and the adhesive force P0 is 5.0 N / 25 mm or more.

[0019] In a sixth aspect of the present invention, for example, in an optical laminate according to any one of the first to fifth aspects, the adhesive strength P1 determined by the following test is 10.0 N / 25 mm or more. Test: The adhesive sheet is attached to alkali-free glass and heat-treated at 60°C for 100 hours. The adhesive sheet is peeled off the alkali-free glass at a peeling speed of 300 mm / min and a peeling angle of 90°. The force required at this time (adhesive force P1) is measured.

[0020] In a seventh aspect of the present invention, for example, in an optical laminate according to any one of the first to sixth aspects, the solvent content in the photocurable composition is 5% by weight or less.

[0021] In the eighth aspect of the present invention, for example, in an optical laminate according to any one of the first to seventh aspects, the adhesive sheet faces the optical film and has a surface that has been surface-modified.

[0022] In the ninth aspect of the present invention, for example, in an optical laminate according to any one of the first to eighth aspects, the adhesive sheet has a surface facing the optical film, and when the surface is treated with trifluoroethanol, the elemental ratio R of fluorine on the surface is 0.1 atomic percent or more.

[0023] In the tenth embodiment of the present invention, for example, in an optical laminate according to any one of the first to ninth embodiments, the optical film faces the adhesive sheet and has a surface that has been surface-modified.

[0024] In an eleventh aspect of the present invention, for example, in an optical laminate according to any one of the first to tenth aspects, the photocurable composition comprises a group of monomers including (meth)acrylic monomers and / or a partial polymer of the monomer group.

[0025] In a twelfth aspect of the present invention, for example, in the optical laminate according to the eleventh aspect, the monomer group includes carboxyl group-containing monomers.

[0026] In a thirteenth aspect of the present invention, for example, in an optical laminate according to the eleventh or twelfth aspect, the monomer group includes ether group-containing monomers.

[0027] In a fourteenth aspect of the present invention, for example, in an optical laminate according to any one of the first to thirteenth aspects, the photocurable composition includes a rework improver.

[0028] In a 15th aspect of the present invention, for example, in the optical laminate according to the 14th aspect, the rework improver is a silane coupling agent.

[0029] In a sixteenth aspect of the present invention, for example, in an optical laminate according to any one of the first to fifteenth aspects, the photocurable composition includes an isocyanate-based crosslinking agent.

[0030] The present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be modified and implemented as appropriate without departing from the spirit of the invention.

[0031] [Embodiment of Optical Laminate] An example of the optical laminate of this embodiment is shown in Figure 1. The optical laminate 10 in Figure 1 includes an adhesive sheet 1 formed from a photocurable composition and at least one optical film 2 selected from the group consisting of polarizing films and phase difference films. Preferably, the adhesive sheet 1 is in direct contact with the optical film 2. The optical laminate 10 may also have a structure in which a base sheet used in the manufacture of the adhesive sheet 1 is laminated onto the adhesive sheet 1. The optical laminate 10 can be used as an optical film with an adhesive sheet.

[0032] The anchoring force F between the adhesive sheet 1 and the optical film 2 is 10.0 N / 25 mm or greater. This level of anchoring force F suppresses delamination between the adhesive sheet 1 and the optical film 2, thereby preventing problems with the image display function of the image display device.

[0033] The anchoring force F between the adhesive sheet 1 and the optical film 2 can be measured by the following method. First, the optical laminate 10 to be evaluated is cut to a size of 25 mm in width and 150 mm in length to make a test piece. Next, the entire surface of the optical film 2 on the test piece is placed on a stainless steel test plate via double-sided tape, and a 2 kg roller is passed back and forth once to press them together. Next, the adhesive sheet 1 on the test piece is placed on an evaluation sheet, and a 2 kg roller is passed back and forth once to press them together. The evaluation sheet has a size of 30 mm in width and 150 mm in length and is not particularly limited as long as it does not peel off from the adhesive sheet 1 during the test. For example, an ITO film (such as 125 Tetrilite OES (manufactured by Oike Kogyo Co., Ltd.)) can be used as the evaluation sheet. Next, using a commercially available tensile testing machine, the average peel force obtained when peeling the adhesive sheet 1 from the optical film 2 at a peel angle of 180° and a tensile speed of 300 mm / min while holding the evaluation sheet is determined as the anchoring force F between the adhesive sheet 1 and the optical film 2. The above test is performed in an atmosphere of 23°C.

[0034] The anchoring force F between the adhesive sheet 1 and the optical film 2 is preferably 11.0 N / 25 mm or more, but may be 12.0 N / 25 mm or more, 13.0 N / 25 mm or more, 14.0 N / 25 mm or more, 15.0 N / 25 mm or more, 16.0 N / 25 mm or more, and even 17.0 N / 25 mm or more. The anchoring force F is preferably greater than 16.0 N / 25 mm. The upper limit of the anchoring force F is not particularly limited, and may be, for example, 50 N / 25 mm or less, and may be 30 N / 25 mm or less.

[0035] (Adhesive sheet) The adhesive sheet 1 has surfaces 1a and 1b facing each other. Surface 1a faces the optical film 2. Surface 1b is exposed, for example, to the outside of the optical laminate 10. The surface 1a of the adhesive sheet 1 may or may not be subjected to a surface modification treatment. According to the surface 1a subjected to the surface modification treatment, there is a tendency to improve the above-mentioned anchoring force F. It is preferable that the surface 1b of the adhesive sheet 1 is not subjected to a surface modification treatment. Examples of the surface modification treatment include corona treatment, plasma treatment, excimer treatment, and frame treatment. It is preferable that the surface 1a is subjected to corona treatment as the surface modification treatment.

[0036] The surface modification treatment may be carried out in an inert gas atmosphere. By performing the surface modification treatment in a state where the oxygen concentration is reduced by an inert gas, the risk of ignition of residual monomers can be reduced. Specifically, it is preferable to perform the surface modification treatment at an oxygen concentration of 8 vol% or less. More preferably, it is 6 vol% or less, and even more preferably, it is 3 vol% or less. If the oxygen concentration is too low, the introduction of functional groups to the surface of the adhesive sheet by the surface modification treatment may be insufficient. Therefore, the oxygen concentration is preferably 0.01 vol% or more, more preferably 0.1 vol% or more, and particularly preferably 0.5 vol% or more. Specific examples of the inert gas include nitrogen and argon. The surface modification treatment may be carried out under normal pressure (1 atm).

[0037] The conditions of the surface modification treatment which is corona treatment are represented by the discharge amount. For example, it is 0.6 to 2 kJ / mThe lower limit of the discharge amount is 2 1 kJ / mor more, 2 2 kJ / mor more, 2 5 kJ / mor more, 2 7 kJ / mor more, 2 10 kJ / mor more, 2 13 kJ / mor more, 2 15 kJ / mor more, 2 20 kJ / mor more, 2 25 kJ / mor more, 2 The upper limit of the discharge amount is 2 30 kJ / mor more, and further 2 35 kJ / m or more may be acceptable. 2 70 kJ / m2 Below, 60kJ / m 2 Below, 50kJ / m 2 Below, 45kJ / m 2 Below, 40kJ / m 2 Below, 30kJ / m 2 Below, 20kJ / m 2 Furthermore, 18 kJ / m³ 2 The following may also be the case: When performing corona treatment in an atmosphere with an oxygen concentration of 10% to 20.9% by volume, the discharge rate should be 1 to 18 kJ / m³. 2 This is also acceptable. When performing corona treatment in an atmosphere with an oxygen concentration of 0.01% to less than 10% by volume, the discharge rate should be 1 to 60 kJ / m³. 2 This may also be the case. By appropriately adjusting the discharge amount of the corona treatment, the above-mentioned anchoring force F tends to improve.

[0038] When the surface 1a of the adhesive sheet 1 is treated with trifluoroethanol, it is preferable that the elemental ratio R of fluorine on the surface 1a is large. The elemental ratio R is, for example, 0.1 atomic% or more, and may be 0.2 atomic% or more, 0.3 atomic% or more, or even 0.4 atomic% or more. The upper limit of the elemental ratio R is, for example, 1.0 atomic% or less.

[0039] The elemental ratio R can be determined by the following method. First, prepare an adhesive sheet 1 cut to 10 mm x 10 mm, and attach the adhesive sheet 1 to the inner wall of a sample tube so that surface 1a is exposed. Add trifluoroethanol (TFE) to this sample tube and bring the vaporized TFE into contact with the adhesive sheet 1. This allows surface 1a to be treated with TFE. Through treatment with TFE, the carboxyl groups present on surface 1a react with TFE, and these carboxyl groups are chemically modified. The reaction between carboxyl groups and TFE is expressed by the following equation. The amount of TFE added to the sample tube should be adjusted so that all carboxyl groups present on surface 1a react with TFE. R-COOH + CF3CH2OH → R-COOCH2CF3

[0040] Next, the adhesive sheet 1 treated with TFE is removed from the sample tube and placed in an X-ray photoelectron spectroscopy analyzer. A wide-scan measurement is performed on the surface 1a of the adhesive sheet 1 using the X-ray photoelectron spectroscopy analyzer, and a qualitative analysis is carried out. This identifies the elements present on the surface 1a. Next, a narrow-scan measurement is performed for each element present on the surface 1a. Based on the results of the narrow-scan measurement, the elemental ratio R of fluorine on the surface 1a can be determined. The fluorine on the surface 1a typically originates from the TFE that has reacted with carboxyl groups. Therefore, the elemental ratio R1 can be used as an indicator of the amount of carboxyl groups present on the surface 1a before the TFE treatment. The larger the elemental ratio R and the greater the amount of carboxyl groups present on the surface 1a, the more likely the anchoring force F described above is to improve. Furthermore, according to the inventors' studies, when the surface 1a is subjected to surface modification treatment, the elemental ratio R tends to increase.

[0041] As described above, the adhesive sheet 1 is formed from a photocurable composition. The photocurable composition is an adhesive composition that forms the adhesive sheet 1 when irradiated with light. The photocurable composition includes, for example, a group of monomers including (meth)acrylic monomers and / or partial polymers of said monomer group. The content of the (meth)acrylic component in the photocurable composition, i.e., (meth)acrylic monomers and their partial polymers, may be 50% by weight or more, 60% by weight or more, 70% by weight or more, or even 80% by weight or more, in which case an acrylic adhesive sheet 1 mainly composed of (meth)acrylic polymers and their crosslinked products can be formed. However, the photocurable composition is not limited to the above examples. In this specification, (meth)acrylic means acrylic and methacrylic. (Meth)acrylate means acrylate and methacrylate.

[0042] Examples of (meth)acrylic monomers are alkyl (meth)acrylates having an alkyl group with 1 to 20 carbon atoms in the side chain. The number of carbon atoms in the alkyl group may be 7 or less, 6 or less, 5 or less, or even 4 or less. The alkyl group may be linear or branched. Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. These include lylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, n-nonyl(meth)acrylate, isononyl(meth)acrylate, n-decyl(meth)acrylate, isodecyl(meth)acrylate, n-dodecyl(meth)acrylate (lauryl(meth)acrylate), n-tridecyl(meth)acrylate, n-tetradecyl(meth)acrylate, pentadecyl(meth)acrylate, hexadecyl(meth)acrylate, heptadecyl(meth)acrylate, and octadecyl(meth)acrylate. The alkyl (meth)acrylate may also be n-butyl(meth)acrylate.

[0043] Of 100 parts by weight of monomers, the amount of alkyl (meth)acrylate is, for example, 40 parts by weight or more, and may be 50 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, 80 parts by weight or more, 85 parts by weight or more, 90 parts by weight or more, or even 95 parts by weight or more. When calculating the amount of a specific monomer, the weight of the partially polymerized product is converted to the weight of each monomer before polymerization.

[0044] The monomer group may include carboxyl group-containing monomers. The carboxyl group-containing monomers may be (meth)acrylic monomers; in other words, (meth)acrylic monomers may contain carboxyl group-containing monomers. Examples of carboxyl group-containing monomers are (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Of 100 parts by weight of the monomer group, the amount of carboxyl group-containing monomers may be, for example, 10 parts by weight or less, 9 parts by weight or less, 8 parts by weight or less, 7 parts by weight or less, 6 parts by weight or less, 5 parts by weight or less, 4.8 parts by weight or less, 4 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, and even 0.5 parts by weight or less. The lower limit of the amount may be, for example, 0.1 parts by weight or more, and in some cases, 0.5 parts by weight or more. The monomer group does not necessarily have to include carboxyl group-containing monomers.

[0045] The monomer group may include hydroxyl group-containing monomers. The hydroxyl group-containing monomers may be (meth)acrylic monomers; in other words, (meth)acrylic monomers may contain hydroxyl group-containing monomers. Hydroxyl group-containing monomers can contribute to improving the cohesive force of the adhesive sheet. Examples of hydroxyl group-containing monomers are 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl acrylate. Preferably, the hydroxyl group-containing monomers are 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate. Of 100 parts by weight of monomers, the amount of hydroxyl group-containing monomers may be, for example, 20 parts by weight or less, and may be 15 parts by weight or less, 10 parts by weight or less, 7.5 parts by weight or less, 5 parts by weight or less, 4 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, or even 0.5 parts by weight or less. The lower limit of the amount may be, for example, 0.01 parts by weight or more, and may be 0.03 parts by weight or more, or even 0.05 parts by weight or more. The monomer group may not contain hydroxyl group-containing monomers.

[0046] The monomer group may include ether group-containing monomers. The ether group-containing monomers may be (meth)acrylic monomers; in other words, (meth)acrylic monomers may contain ether group-containing monomers. The ether group-containing monomers can contribute to improving the anchoring force F described above.

[0047] The ether group-containing monomer is preferably an alkoxy group-containing monomer. Examples of alkoxy group-containing monomers include the alkylene oxide adduct shown in the following chemical formula (1). R in formula (1) 1 R is either a hydrogen atom or a methyl group. 2 R is an alkyl group. The alkyl group may be linear or branched. 2R is preferably a linear alkyl group. 2 Examples include methyl and ethyl groups. In formula (1), n ​​is an integer from 1 to 30, preferably from 1 to 12, and may also be an integer from 1 to 5. [ka]

[0048] Examples of alkylene oxide adducts shown in formula (1) are 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate, preferably 2-methoxyethyl acrylate (MEA).

[0049] The ether group-containing monomer is not limited to the alkylene oxide adducts described above. The ether group-containing monomer may have a ring structure, and this ring structure may contain an ether group. Examples of ring structures containing an ether group include a tetrahydrofuran ring and a dioxane ring. Examples of ether group-containing monomers with a ring structure are cyclic trimethylolpropaneform (meth)acrylate and tetrahydrofurfuryl (meth)acrylate.

[0050] Of the 100 parts by weight of monomers, the amount of ether group-containing monomers is, for example, 1 part by weight or more, and may be 5 parts by weight or more, 10 parts by weight or more, 20 parts by weight or more, 25 parts by weight or more, 30 parts by weight or more, 40 parts by weight or more, 50 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, 80 parts by weight or more, and even 90 parts by weight or more. The upper limit of the amount is, for example, 99 parts by weight or less, and in some cases may be 50 parts by weight or less. The monomer group does not have to contain ether group-containing monomers.

[0051] In the photocurable composition, each of the above-mentioned monomers may be included as a partial polymer. The partial polymer may be either a monopolymer or a copolymer. The partial polymer can contribute to the stable formation of the coating layer described later by moderately increasing the viscosity of the photocurable composition.

[0052] Photocurable compositions typically contain photopolymerization initiators. Examples of photopolymerization initiators are photoradical generators that generate radicals in response to visible light and / or ultraviolet light with wavelengths shorter than 450 nm.

[0053] Examples of photopolymerization initiators include benzoin ethers such as benzoin methyl ether, benzoin isopropyl ether, and benzyldimethyl ketal; substituted benzoin ethers such as anisole methyl ether; substituted acetophenones such as 2,2-diethoxyacetophenone and 2,2-dimethoxy-2-phenylacetophenone; α-hydroxyalkylphenones such as 1-hydroxycyclohexyl-phenyl ketone; substituted alpha ketols such as 2-methyl-2-hydroxypropiophenone; aromatic sulfonyl chlorides such as 2-naphthalenesulfonyl chloride; photoactive oximes such as 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime; and benzophenone compounds such as benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylic benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, and 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone. Thioxanthone compounds such as thioxanthone, 2-chlorthioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and 2,4-diethylthioxanthone; 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, and 2-(p-tolyl)-4,6-bis(trichloromethyl)-s-triazine Triazine compounds such as 2-piperonyl-4,6-bis(trichloromethyl)-s-triazine, 2,4-bis(trichloromethyl)-6-styryl-s-triazine, 2-(naphtho-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxynaphtho-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-trichloromethyl-(piperonyl)-6-triazine, and 2,4-trichloromethyl-(4'-methoxystyryl)-6-triazine;These include oxime ester compounds such as 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyl oxime)], and O-(acetyl)-N-(1-phenyl-2-oxo-2-(4'-methoxynaphthyl)ethylidene)hydroxylamine; phosphine compounds such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; quinone compounds such as 9,10-phenanthylenequinone, camphorquinone, and ethylanthraquinone; borate compounds; carbazole compounds; imidazole compounds; and titanocene compounds. The photocurable composition may contain one or more photopolymerization initiators.

[0054] The amount of photopolymerization initiator in the photocurable composition is, for example, 0.02 to 10 parts by weight, or 0.05 to 5 parts by weight, per 100 parts by weight of the monomer group and its partial polymers.

[0055] The photocurable composition may contain a crosslinking agent. An example of a crosslinking agent is a polyfunctional monomer having two or more polymerizable functional groups in one molecule. The polyfunctional monomer may be a (meth)acrylic monomer. Examples of polyfunctional monomers are monomers having two or more C=C bonds in one molecule, and monomers having one or more C=C bonds and one or more polymerizable functional groups such as epoxy groups, aziridine groups, oxazoline groups, hydrazine groups, or methylol groups in one molecule. The polyfunctional monomer is preferably a monomer having two or more C=C bonds in one molecule.

[0056] Examples of polyfunctional monomers include (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 1,9-nonanediol diacrylate (N Polyfunctional acrylates such as DDA, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate (ester compounds of polyhydric alcohols and (meth)acrylic acid, etc.); allyl(meth)acrylate, vinyl(meth)acrylate, divinylbenzene, epoxyacrylate, polyester acrylate, urethane acrylate, butyl di(meth)acrylate, and hexyl di(meth)acrylate. The polyfunctional monomer is preferably a polyfunctional acrylate, and more preferably trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0057] The crosslinking agent may include other crosslinking agents besides the polyfunctional monomers mentioned above. Examples of other crosslinking agents include isocyanate-based crosslinking agents. The photocurable composition may contain an isocyanate-based crosslinking agent, and it is preferable to contain both the polyfunctional monomers and the isocyanate-based crosslinking agent. The isocyanate-based crosslinking agent may contribute to improving the anchoring force F mentioned above.

[0058] As an isocyanate crosslinking agent, a compound having at least two isocyanate groups (isocyanate compound) can be used. Preferably, the number of isocyanate groups in the isocyanate compound is three or more. The upper limit of the number of isocyanate groups is not particularly limited, but is, for example, five. Examples of isocyanate compounds include aromatic isocyanate compounds, alicyclic isocyanate compounds, and aliphatic isocyanate compounds.

[0059] Examples of aromatic isocyanate compounds include phenylenediisocyanate, 2,4-tolylenediisocyanate, 2,6-tolylenediisocyanate, 2,2'-diphenylmethanediisocyanate, 4,4'-diphenylmethanediisocyanate, 4,4'-toluidinediisocyanate, 4,4'-diphenyletherdiisocyanate, 4,4'-diphenyldiisocyanate, 1,5-naphthalenediisocyanate, and xylylenediisocyanate.

[0060] Examples of alicyclic isocyanate compounds include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated tolylene diisocyanate, and hydrogenated tetramethylxylylene diisocyanate.

[0061] Examples of aliphatic isocyanate compounds include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate (PDI), 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0062] Examples of isocyanate-based crosslinking agents include polymers (dimers, trimers, pentamers, etc.) of the above-mentioned isocyanate compounds, adducts obtained by adding them to polyhydric alcohols such as trimethylolpropane, urea-modified compounds, biuret-modified compounds, allophanate-modified compounds, isocyanurate-modified compounds, carbodiimide-modified compounds, urethane prepolymers obtained by adding them to polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, etc.

[0063] The isocyanate crosslinking agent preferably includes an aliphatic isocyanate compound and / or a derivative of an aliphatic isocyanate compound. It is particularly preferable that the isocyanate crosslinking agent is at least one selected from the group consisting of pentamethylene diisocyanate (PDI) crosslinking agents (PDI and its derivatives) and hexamethylene diisocyanate (HDI) crosslinking agents (HDI and its derivatives). Specific examples of PDI crosslinking agents include isocyanurate-modified PDI. Specific examples of HDI crosslinking agents include isocyanurate-modified and biuret-modified HDI.

[0064] The amount of crosslinking agent in a photocurable composition varies depending on the molecular weight, number of functional groups, etc., but is, for example, 5 parts by weight or less per 100 parts by weight of the monomer group and its partial polymers, and may be 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, or even 0.5 parts by weight or less. The lower limit of the amount is, for example, 0.01 parts by weight or more, and may even be 0.05 parts by weight or more.

[0065] Furthermore, when the photocurable composition contains an isocyanate-based crosslinking agent, the amount of the isocyanate-based crosslinking agent is, for example, 0.02 parts by weight or more per 100 parts by weight of the total of the monomer group and its partial polymers, and may be 0.05 parts by weight or more, 0.1 parts by weight or more, 0.5 parts by weight or more, or even 1 part by weight or more. When the photocurable composition contains an isocyanate-based crosslinking agent, adjusting the amount of hydroxyl group-containing monomers in the photocurable composition to a smaller value tends to further improve the anchoring force F.

[0066] When an isocyanate-based crosslinking agent is added, the adhesive sheet may harden, especially in high-temperature environments. In such cases, the stress relaxation properties of the adhesive sheet are impaired, making it easier for expansion and contraction stresses of the optical film to be transmitted to the interface between the adhesive sheet and the adherend, which tends to cause peeling. If the anchoring force between the adhesive sheet and the optical film can be ensured by means other than the addition of an isocyanate-based crosslinking agent, it is desirable that the photocurable composition does not contain an isocyanate-based crosslinking agent.

[0067] The photocurable composition may further contain a rework improver. The rework improver is a component that reduces the adhesive strength (for example, the adhesive strength P0 described later) between the adhesive sheet 1 and the adherend by segregating on the surface of the adherend when the adhesive sheet 1 is attached to the adherend such as alkali-free glass or a transparent conductive layer.

[0068] The rework enhancer may be, for example, a silane coupling agent having an alkoxysilyl group, and it is preferable that it further has a polar group in addition to the alkoxysilyl group. Specific examples of alkoxy groups included in the alkoxysilyl group in the rework enhancer are methoxy groups, ethoxy groups, etc. Examples of polar groups include carboxyl groups, acid anhydride groups, and epoxy groups. The carboxyl group may be a group produced by the hydrolysis of an acid anhydride group. Examples of acid anhydride groups include carboxylic acid anhydride groups such as succinic anhydride, phthalic anhydride, and maleic anhydride. The rework enhancer may also have ether groups other than epoxy groups, and may have a polyether skeleton.

[0069] The rework improver preferably has at least one selected from the group consisting of acid anhydride groups and epoxy groups. When a rework improver having acid anhydride groups or epoxy groups is used, the adhesive strength (adhesion strength P1 described later) between the adhesive sheet 1 and the glass tends to be improved by heat treatment after attaching the adhesive sheet 1 to alkali-free glass.

[0070] Examples of rework enhancers include alkoxysilane compounds having polar groups, organopolysiloxane compounds having polar groups and alkoxysilyl groups, and polyether compounds having alkoxysilyl groups.

[0071] Examples of alkoxysilane compounds having polar groups include 2-trimethoxysilylethyl succinic anhydride, 3-trimethoxysilylpropyl succinic anhydride (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X-12-967C"), 3-triethoxysilylpropyl succinic anhydride, 3-methyldiethoxysilylpropyl succinic anhydride, and 1-carboxy-3-triethoxysilylpropyl succinic anhydride.

[0072] Examples of organopolysiloxane compounds having polar groups and alkoxysilyl groups include acid anhydride group-containing oligomer-type silane coupling agents (product name "X-24-9591F") and epoxy group-containing oligomer-type silane coupling agents (product names "X-41-1053", "X-41-1059A", "X-41-1056", "X-40-2651", etc.) manufactured by Shin-Etsu Chemical Co., Ltd.

[0073] Examples of polyether compounds containing alkoxysilyl groups include MS Polymer S203, S303, S810, SILYL EST250, EST280, SAT10, SAT200, SAT220, SAT350, and SAT400 from Kaneka Corporation, and EXCESTAR S2410, S2420, and S3430 from Asahi Glass Co., Ltd.

[0074] The amount of rework improver in the photocurable composition is, for example, 0.01 parts by weight or more, but may be 0.05 parts by weight or more, 0.1 parts by weight or more, 0.2 parts by weight or more, 0.5 parts by weight or more, or even 0.6 parts by weight or more, based on 100 parts by weight total of monomers and their partial polymers. The upper limit of the amount is, for example, 10 parts by weight or less, but may be 5 parts by weight or less, or even 1 part by weight or less. The photocurable composition may not contain a rework improver.

[0075] The photocurable composition may contain additives other than those mentioned above. Examples of additives include chain transfer agents, silane coupling agents other than rework improvers, viscosity modifiers, tackifiers, plasticizers, softeners, antioxidants, fillers, colorants, antioxidants, surfactants, antistatic agents, and ultraviolet absorbers.

[0076] The solvent content in the photocurable composition may be, for example, 5% by weight or less, but may also be 4% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, or even 0.5% by weight or less. The photocurable composition may not contain substantially any solvent. Substantially solvent-free means that a solvent derived from additives, etc., may be permitted at a content of, for example, 0.1% by weight or less, preferably 0.05% by weight or less, and more preferably 0.01% by weight or less.

[0077] The viscosity of the photocurable composition is preferably 5 to 150 poise. Photocurable compositions having a viscosity within the above range are particularly suitable for forming the coating layer described later.

[0078] The polymerization rate of the monomer group in the adhesive sheet 1 is preferably 90% or higher. The polymerization rate may be 95% or higher, 98% or higher, or even 99% or higher.

[0079] The gel fraction of the adhesive sheet 1 is, for example, 50% or more, and may be 75% or more, 80% or more, or even 85% or more.

[0080] The creep amount of the adhesive sheet 1 is, for example, 500 μm or less, and may be 300 μm or less, 180 μm or less, 160 μm or less, 150 μm or less, 100 μm or less, or even 50 μm or less. The lower limit of the creep amount is, for example, 5 μm or more, and may be 10 μm or more, or even 20 μm or more.

[0081] The creep amount of the adhesive sheet 1 can be evaluated as follows (see Figures 2A and 2B). First, the laminate of the adhesive sheet 1 and the support film 51 to be evaluated is cut into strips of 10 mm × 50 mm to form a test piece 52. The support film 51 is placed to suppress the deformation of the part of the adhesive sheet 1 to which the load is applied during the test, thereby enabling more accurate measurement of the creep amount. For example, a resin film such as polyethylene terephthalate (PET) film can be used for the support film 51. The support film 51 may also be an optical film or a laminate containing an optical film. The thickness of the support film 51 should be such that it does not deform under the load, for example, 20 to 200 μm. Next, as shown in Figures 2A and 2B, the test piece 52 is attached to the surface of the stainless steel test plate 53 with the adhesive sheet 1 at a joint surface of 10 mm vertically × 10 mm horizontally. Note that Figure 2B is the cross-section BB of Figure 2A. The test specimen 52 is attached to the test plate 53 in a manner that prevents air bubbles from being introduced between the test plate 53 and the adhesive sheet 1. After attachment, the test plate 53 and the adhesive sheet 1 are placed in an autoclave at 50°C and 5 atmospheres (absolute pressure) for 15 minutes to homogenize the bond. Next, the test plate 53 and the test specimen 52 are held vertically with the test plate 53 facing upwards and left in a 25°C atmosphere for at least 5 minutes. Then, with the test plate 53 fixed, a 500g weight is fixed to the center of the lower end of the test specimen 52, and a load of 500gf is applied vertically downwards. The amount of creep (slippage) of the adhesive sheet 1 relative to the test plate 53 at 3600 seconds after the start of applying the load 54 is measured as the amount the weight fell. A laser displacement meter can be used to measure the amount the weight fell.

[0082] The thickness of the adhesive sheet 1 is, for example, 500 μm or less, and may be 250 μm or less, 150 μm or less, 100 μm or less, 50 μm or less, 30 μm or less, 25 μm or less, or even 20 μm or less. The lower limit of the thickness of the adhesive sheet 1 is, for example, 2 μm or more, and may be 5 μm or more.

[0083] (Optical film) The optical film 2 has a surface 2a facing the adhesive sheet 1. Surface 2a is in contact with, for example, the surface 1a of the adhesive sheet 1. Surface 2a of the optical film 2 may be subjected to a surface modification treatment. Surface 2a that has been subjected to a surface modification treatment tends to improve the anchoring force F. Examples of surface modification treatments for surface 1a include those described above.

[0084] It is preferable that surface 2a is subjected to corona treatment as a surface modification treatment. When surface 2a is subjected to corona treatment, conditions such as the discharge amount can be appropriately adjusted, for example, within the range described above for surface 1a.

[0085] As described above, the optical film 2 includes at least one selected from the group consisting of a polarizing film and a phase difference film. The optical film 2 may be a laminated film including a polarizing film and / or a phase difference film. The optical film 2 may also include a glass film. However, the optical film 2 is not limited to the above examples.

[0086] A polarizing film includes a polarizer. Typically, a polarizing film includes a polarizer and a protective film (a transparent protective film). The protective film is, for example, positioned in contact with the main surface (the surface with the largest area) of the polarizer. The polarizer may be positioned between two protective films. The protective film may be positioned on at least one surface of the polarizer.

[0087] The polarizer is not particularly limited and includes, for example, hydrophilic polymer films such as polyvinyl alcohol-based films, partially formalized polyvinyl alcohol-based films, and partially saponified ethylene-vinyl acetate copolymer films, on which dichroic substances such as iodine and dichroic dyes are adsorbed and then uniaxially stretched; and polyene-based oriented films such as dehydrated polyvinyl alcohol products and dehydrochlorinated polyvinyl chloride products. Typically, the polarizer consists of a polyvinyl alcohol-based film (polyvinyl alcohol-based films include partially saponified ethylene-vinyl acetate copolymer films) and a dichroic substance such as iodine.

[0088] The thickness of the polarizer is not particularly limited and may be, for example, 80 μm or less, but may also be 50 μm or less, 30 μm or less, 25 μm or less, or even 20 μm or less. The lower limit of the polarizer thickness is not particularly limited and may be, for example, 1 μm or more, but may also be 5 μm or more, 10 μm or more, or even 15 μm or more. Thin polarizers (for example, with a thickness of 20 μm or less) have suppressed dimensional changes and can contribute to improving the durability of the optical laminate, especially its durability at high temperatures.

[0089] As the material for the protective film, for example, a thermoplastic resin that is excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, etc., can be used. Specific examples of such thermoplastic resins include cellulose resins such as triacetylcellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (norbornene-based resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The material for the protective film may also be a thermosetting resin or an ultraviolet-curable resin such as (meth)acrylic, urethane, acrylic-urethane, epoxy, or silicone-based resin. If the polarizing film has two protective films, the materials of the two protective films may be the same or different. For example, a protective film made of a thermoplastic resin may be bonded to one main surface of the polarizer via an adhesive, and a protective film made of a thermosetting resin or an ultraviolet-curable resin may be bonded to the other main surface of the polarizer. The protective film may contain one or more additives. Examples of additives include UV absorbers, antioxidants, lubricants, plasticizers, mold release agents, color inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, and colorants.

[0090] Furthermore, films containing (meth)acrylic resin tend to have low adhesive strength with adhesive sheets. However, in this embodiment, by taking measures such as applying a surface modification treatment to the surface 2a of the optical film 2, the anchoring force F can be adjusted to a sufficiently high value even when the surface of the protective film containing (meth)acrylic resin corresponds to the surface 2a of the optical film 2.

[0091] The thickness of the protective film can be determined as appropriate, but generally it is around 10 to 200 μm, considering factors such as strength, ease of handling, and thinness.

[0092] The polarizer and protective film are typically bonded together via a water-based adhesive. Examples of water-based adhesives include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latex, water-based polyurethane, and water-based polyester. Other adhesives besides those mentioned above include UV-curing adhesives and electron beam-curing adhesives. Electron beam-curing adhesives for polarizers exhibit suitable adhesion to various protective films. The adhesive may also contain metal compound fillers.

[0093] In polarizing films, a phase difference film or the like can be formed on the polarizer instead of a protective film. Furthermore, another protective film, a phase difference film, or the like can be added on top of the protective film.

[0094] Regarding the protective film, a hard coat layer may be provided on the surface that is in contact with the polarizer and the surface facing it, and treatments for purposes such as anti-reflection, anti-sticking, diffusion, and anti-glare may be applied.

[0095] The polarizing film may also be a circularly polarizing film.

[0096] As the phase difference film, one obtained by stretching a polymer film or one obtained by oriented and immobilizing a liquid crystal material can be used. The phase difference film has birefringence in the in-plane direction and / or in the thickness direction, for example.

[0097] Phase difference films include anti-reflective phase difference films (see Japanese Patent Publication No. 2012-133303

[0221] ,

[0222] ,

[0228] ), viewing angle compensation phase difference films (see Japanese Patent Publication No. 2012-133303

[0225] ,

[0226] ), and tilt-oriented phase difference films for viewing angle compensation (see Japanese Patent Publication No. 2012-133303

[0227] ).

[0098] The specific configuration of the phase difference film, such as the phase difference value, arrangement angle, three-dimensional birefringence, and whether it is single-layer or multi-layer, is not particularly limited, and known phase difference films can be used.

[0099] The thickness of the phase difference film is preferably 20 μm or less, more preferably 10 μm or less, even more preferably 1 to 9 μm, and particularly preferably 3 to 8 μm.

[0100] The phase difference film may include, for example, quarter-wave plates and / or half-wave plates on which liquid crystal material is oriented and fixed.

[0101] (Method of manufacturing optical laminates) The optical laminate 10 can be manufactured, for example, by the following method. First, as shown in Figures 3A and 3B, a first laminate 15 is prepared, comprising a base sheet 21, a coating layer 22 containing a photocurable composition, and a release liner 23 in that order. By irradiating the first laminate 15 with light 14, an adhesive sheet 1 can be formed from the coating layer 22 (Figure 3C).

[0102] The first laminate 15 is typically irradiated with light 14 from the side of the base sheet 21 (Figure 3A). At this time, the light 14 penetrates the base sheet 21 and reaches the coating layer 22, curing the coating layer 22. However, the irradiation with light 14 may be carried out from the side of the release liner 23, or from both the release liner 23 and the base sheet 21 (Figure 3B). The adhesive sheet 1 formed from the coating layer 22 is sandwiched between the base sheet 21 and the release liner 23 and constitutes part of the second laminate 16 until the release liner 23 is peeled off.

[0103] An example of the base material of the peel-off liner 23 (hereinafter referred to as "liner base material") is a resin film. Examples of resins that may be included in the liner base material are polyesters such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyethersulfones, polycarbonates, polyamides, polyimides, polyolefins, (meth)acrylic resins, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyarylate, and polyphenylene sulfide. The resin is preferably a polyester such as polyethylene terephthalate.

[0104] The release liner 23 may have light transmission properties 14, and may have light transmission properties 14 similar to those of the base sheet 21.

[0105] The thickness of the release liner 23 is, for example, 10 to 200 μm, and may be 25 to 150 μm.

[0106] The peel-off liner 23 may include layers other than the liner substrate. The peel-off liner 23 may include a release layer. For example, the peel-off liner 23 comprises a liner substrate and a release layer formed on one side of the liner substrate. This peel-off liner 23 can be used such that the release layer is on the side of the coating layer 22.

[0107] The release layer is typically a cured layer of a release agent composition containing a release agent. Various release agents can be used, such as silicone-based release agents, fluorine-based release agents, long-chain alkyl-based release agents, fatty acid amide-based release agents, and silica powder. The release liner 23 may also have a cured layer of a release agent composition mainly containing a silicone-based release agent (hereinafter referred to as the "silicone release layer"). The silicone release layer is particularly suitable for achieving both adhesion and release properties to the adhesive sheet 1. In this specification, the main component refers to the component with the highest content.

[0108] The silicone-based release agent is, for example, a variety of curable silicone materials such as addition reaction type, condensation reaction type, ultraviolet curing type, electron beam curing type, and solvent-free type, with addition reaction curing type silicone materials being preferred. Addition reaction curing type silicone materials are particularly suitable for forming a release layer that achieves both adhesion and release properties to the adhesive sheet 1. The curable silicone material may also be a silicone-modified resin obtained by introducing reactive silicone into an organic resin such as urethane, epoxy, or alkyd resin by graft polymerization or the like.

[0109] An example of an addition-curing silicone material is a polyorganosiloxane having a vinyl group or an alkenyl group in its molecule. The addition-curing silicone material does not necessarily have a hydrosilyl group. Examples of alkenyl groups include 3-butenyl, 4-pentenyl, 5-hexenyl, 6-heptenyl, 7-octenyl, 8-nonenyl, 9-decenyl, 10-undecenyl, and 11-dodecenyl. Examples of polyorganosiloxanes include polyalkylalkylsiloxanes such as polydimethylsiloxane, polydiethylsiloxane, and polymethylethylsiloxane, polyalkylarylsiloxanes, and copolymers of multiple Si atom-containing monomers such as poly(dimethylsiloxane-diethylsiloxane). The polyorganosiloxane is preferably polydimethylsiloxane.

[0110] A mold release agent composition containing a silicone-based mold release agent as its main component (hereinafter referred to as "silicone mold release agent composition") usually contains a crosslinking agent. An example of a crosslinking agent is a polyorganosiloxane having hydrosilyl groups. The crosslinking agent may have two or more hydrosilyl groups in a single molecule.

[0111] The silicone release agent composition may contain a curing catalyst. An example of a curing catalyst is a platinum-based catalyst. Examples of platinum-based catalysts include chloroplatinic acid, platinum olefin complexes, and chloroplatinic acid olefin complexes. The amount of platinum-based catalyst used is, for example, 10 to 1000 ppm (by weight, in terms of platinum) relative to the total solid content of the composition.

[0112] The silicone release agent composition may contain additives. Examples of additives are release control agents and adhesion improvers. Examples of release control agents are unreactive silicone resins, and more specifically, organosiloxanes such as octamethylcyclotetrasiloxane and MQ resins. The amount of release control agents and adhesion improvers used is, for example, 1 to 30% by weight in total with respect to the total solid content of the composition. Further examples of additives are fillers, antistatic agents, antioxidants, UV absorbers, plasticizers and colorants. The amount of further additives used is, for example, 10% by weight or less in total with respect to the total solid content of the composition.

[0113] The silicone release agent composition may contain organic solvents. Examples of organic solvents include hydrocarbon solvents such as cyclohexane, n-hexane, and n-heptane; aromatic solvents such as toluene and xylene; ester solvents such as ethyl acetate and methyl acetate; ketone solvents such as acetone and methyl ethyl ketone; and alcohol solvents such as methanol, ethanol, and butanol. Two or more organic solvents may be included. The amount of organic solvent used is preferably 80 to 99.9% by weight of the silicone release agent composition.

[0114] The release layer can be formed, for example, by heating and drying a coating film containing a release agent composition formed on a liner substrate. Various coating methods can be applied to the release agent composition, such as roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and die coating. For heating and drying, for example, hot air drying can be applied. The heating temperature and time vary depending on the heat resistance of the liner substrate, but are usually around 80 to 150°C and 10 seconds to 10 minutes. If necessary, irradiation with active energy rays such as ultraviolet light may be used in combination.

[0115] The thickness of the release layer is, for example, 10 to 300 nm. The upper limit of the thickness may be 200 nm or less, 150 nm or less, 120 nm or less, 110 nm or less, 100 nm or less, less than 100 nm, 90 nm or less, 80 nm or less, 70 nm or less, less than 70 nm, and even 65 nm or less. The lower limit of the thickness may be 15 nm or more, 20 nm or more, 25 nm or more, 30 nm or more, 35 nm or more, 40 nm or more, 45 nm or more, and even 50 nm or more.

[0116] The release liner 23 may be in the form of a single sheet or a long strip.

[0117] An example of the base sheet 21 is a resin film. An example of the resin contained in the base sheet 21 is the same as an example of the resin that may be contained in the liner base material.

[0118] The base sheet 21 preferably has excellent light transmittance 14.

[0119] The thickness of the base sheet 21 is, for example, 10 to 200 μm, and may be 25 to 150 μm.

[0120] The base sheet 21 may have a release layer on the side facing the coating layer 22. Examples of release layers that the base sheet 21 may have and their manufacturing methods are the same as examples of release layers that the release liner 23 may have and their manufacturing methods. Both the release liner 23 and the base sheet 21 may have release layers. In this case, both release layers may be formed from a release agent composition containing the same release agent as its main component. The thicknesses of the two release layers may also differ; for example, the release layer on the base sheet 21 may be thicker.

[0121] For the base sheet 21, it is usually possible to select a sheet with a greater peeling force from the adhesive sheet 1 compared to the peeling liner 23.

[0122] The base sheet 21 may be in the form of a single leaf or a long length.

[0123] The first laminate 15 can be formed, for example, by forming a coating layer 22 on a base sheet 21 (or release liner 23) and then placing the release liner 23 (or base sheet 21) on the formed coating layer 22. Alternatively, the first laminate 15 may be formed by pouring a photocurable composition into the space between the base sheet 21 and the release liner 23, which are held at a predetermined distance apart so that their main surfaces face each other.

[0124] Various coating methods can be applied to form the coated layer 22, including roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and die coating.

[0125] The thickness of the coating layer 22 can be adjusted according to the desired thickness of the adhesive sheet 1, for example, from 5 to 500 μm, but may also be 5 to 250 μm, 5 to 150 μm, 5 to 100 μm, 5 to 50 μm, 5 to 30 μm, 5 to 25 μm, or even 5 to 20 μm.

[0126] The light 14 irradiated onto the first laminate 15 is, for example, visible light or ultraviolet light having a wavelength shorter than 450 nm. The light 14 may include light with wavelengths in the same region as the absorption wavelength of the photopolymerization initiator contained in the photocurable composition. Light 14 with short wavelengths of 300 nm or less cut off by a filter or the like may be used for irradiation, and cutting off short wavelengths is suitable for suppressing the degradation of the substrate sheet 21 by the light 14. The light source for the light 14 is, for example, a light irradiation device equipped with an ultraviolet irradiation lamp. Examples of ultraviolet irradiation lamps include ultraviolet LEDs, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, microwave-excited mercury lamps, black light lamps, chemical lamps, germicidal lamps, low-pressure discharge mercury lamps, and excimer lasers. Two or more ultraviolet irradiation lamps may be combined.

[0127] The irradiation of light 14 may be continuous or intermittent.

[0128] The illuminance of light 14 is, for example, 1-20 mW / cm². 2 The irradiation time of light 14 is, for example, 5 minutes to 5 hours. The integrated light amount of light 14 on the first laminate 15 is, for example, 100 to 5000 mJ / cm². 2 That is the case.

[0129] Next, the release liner 23 is peeled off the second laminate 16, exposing the surface of the adhesive sheet 1. By placing the optical film 2 on the exposed surface of the adhesive sheet 1, the optical laminate 10 can be manufactured. Before placing the optical film 2, the exposed surface of the adhesive sheet 1 may be subjected to a surface modification treatment.

[0130] (Characteristics of optical laminates) From the viewpoint of reworkability, it is preferable that the optical laminate 10 has an adhesive strength P0 of 8.0 N / 25 mm or less, as determined by the following test 1. Test 1: Adhesive sheet 1 is attached to alkali-free glass, and adhesive sheet 1 is peeled off from the alkali-free glass at a peeling speed of 300 mm / min and a peeling angle of 90°. The force required at this time (adhesive force P0) is measured.

[0131] Test 1 is performed by the following method. First, the optical laminate 10 is cut into strips measuring 150 mm in length and 25 mm in width to form test pieces. Next, the test pieces are attached to alkali-free glass via an adhesive sheet 1. Alkali-free glass is glass that substantially does not contain alkali components (alkali metal oxides), and more specifically, the weight ratio of alkali components in the glass is, for example, 1000 ppm or less, and moreover, 500 ppm or less. The alkali-free glass is, for example, in the form of a plate and has a thickness of 0.5 mm or more.

[0132] The test specimen is attached to the alkali-free glass, for example, using a laminator, ensuring that no air bubbles are introduced between the alkali-free glass and the adhesive sheet 1. After attaching the test specimen, it is placed in an autoclave at 50°C and 5 atmospheres (absolute pressure) for 15 minutes to homogenize the bond between the alkali-free glass and the adhesive sheet 1, and to ensure that the adhesive sheet 1 adheres tightly to the alkali-free glass. Next, the test specimen is peeled off the alkali-free glass at a peeling speed of 300 mm / min and a peeling angle of 90° (measurement length 80 mm). At this time, the force required to peel the test specimen off the alkali-free glass is measured at intervals of 0.5 s (1 measurement). The average of the obtained measurements is identified as the adhesive force P0.

[0133] The adhesive strength P0 is preferably 7.0 N / 25 mm or less, but may also be 6.0 N / 25 mm or less, 5.0 N / 25 mm or less, 4.5 N / 25 mm or less, 4.0 N / 25 mm or less, and even 3.5 N / 25 mm or less. The lower limit of the adhesive strength P0 is, for example, 0.5 N / 25 mm or more, but may also be 1.0 N / 25 mm or more, and even 1.5 N / 25 mm or more. The adhesive strength P0 is preferably 0.5 to 7.0 N / 25 mm.

[0134] The difference between the anchoring force F and the adhesive force P0 (F-P0) is preferably 5.0 N / 25 mm or more, but may also be 6.0 N / 25 mm or more, 7.0 N / 25 mm or more, 8.0 N / 25 mm or more, 9.0 N / 25 mm or more, 10.0 N / 25 mm or more, 11.0 N / 25 mm or more, 12.0 N / 25 mm or more, and even 13.0 N / 25 mm or more. The upper limit of the difference (F-P0) is, for example, 20 N / 25 mm or less.

[0135] Furthermore, from the viewpoint of durability, it is preferable that the adhesive sheet 1 of the optical laminate 10 has improved adhesion when it is heat-treated in contact with alkali-free glass. As an example, it is preferable that the adhesive strength P1 of the optical laminate 10, as determined by the following test 2, is 8.0 N / 25 mm or more. Test 2: Adhesive sheet 1 is attached to alkali-free glass and heat-treated at 60°C for 100 hours. Adhesive sheet 1 is peeled off from the alkali-free glass at a peeling speed of 300 mm / min and a peeling angle of 90°. The force required at this time (adhesive force P1) is measured.

[0136] Test 2 can be carried out in the same manner as Test 1, except that after homogenizing the bond between the alkali-free glass and the adhesive sheet 1 in an autoclave, it is heat-treated at 60°C for 100 hours under atmospheric pressure, and then the temperature of the test specimen is lowered to room temperature (e.g., 23°C) before peeling the test specimen from the alkali-free glass.

[0137] The adhesive strength P1 is preferably 9.0 N / 25 mm or more, but may also be 9.5 N / 25 mm or more, 10.0 N / 25 mm or more, or even 10.5 N / 25 mm or more. The upper limit of the adhesive strength P1 is, for example, 20 N / 25 mm or less.

[0138] Another example of the optical laminate of this embodiment is shown in Figure 4. The optical laminate 11 in Figure 4 has a laminated structure in which an adhesive sheet 1A, an optical film 2A, an adhesive sheet 1B, and an optical film 2B are laminated in this order. The optical laminate 11 may also have a structure in which the base sheet used when manufacturing the adhesive sheet 1A is laminated onto the adhesive sheet 1A.

[0139] In the optical laminate 11, typically, optical film 2A is a phase difference film and optical film 2B is a polarizing film. The adhesive sheet 1B functions as an interlayer adhesive between optical films 2A and 2B. The adhesive sheet 1B may use a known adhesive.

[0140] The optical laminate of this embodiment can be distributed and stored, for example, as a wound body formed by winding a strip-shaped optical laminate, or as a single-sheet optical laminate.

[0141] The optical laminate of this embodiment is typically used in an image display device. The image display device can be formed, for example, by bonding the optical laminate 10 or 11 to an image display panel. Bonding is performed, for example, by an adhesive sheet 1. The image display device may be an organic EL display or a liquid crystal display. However, the image display device is not limited to the above examples. The image display device may be an electroluminescent (EL) display, a plasma display (PD), a field emission display (FED), etc. The image display device can be used for home appliance applications, automotive applications, public information display (PID) applications, etc. [Examples]

[0142] The present invention will be described in more detail below with reference to examples. The present invention is not limited to the examples shown below.

[0143] [Polarizing film] First, an 80 μm thick polyvinyl alcohol film was stretched to 3 times its original thickness while being stained for 1 minute in a 0.3% iodine solution at 30°C between rolls with different speed ratios. Next, it was stretched to a total stretch ratio of 6 times while being immersed for 0.5 minutes in an aqueous solution at 60°C containing 4% boric acid and 10% potassium iodide. Then, after being washed by immersion for 10 seconds in an aqueous solution at 30°C containing 1.5% potassium iodide, it was dried at 50°C for 4 minutes to obtain a polarizer with a thickness of 28 μm. A 30 μm thick transparent protective film made of a modified acrylic polymer having a lactone ring structure was laminated to one side of the polarizer using a polyvinyl alcohol-based adhesive. Furthermore, a 47 μm thick transparent protective film, consisting of a triacetylcellulose film (manufactured by Konica Minolta, product name "KC4UY") with a hard coat layer (HC), was laminated to the other side of the polarizer using a polyvinyl alcohol-based adhesive. The polarizing film was fabricated by heating and drying it in an oven set to 70°C for 5 minutes. In addition, a discharge of 63 W / m was applied to the surface of the polarizing film on the side of the transparent protective film made of a modified acrylic polymer. 2 Corona treatment was performed using min.

[0144] [Removable Liner A] A silicone-based mold release agent composition was obtained by mixing 30 parts by weight of addition-curing silicone (LTC761 containing a hexenyl group-containing polyorganosiloxane, 30% by weight toluene solution, manufactured by Toray Dow Corning), 0.9 parts by weight of a release control agent (BY24-850 containing an unreactive silicone resin, manufactured by Toray Dow Corning), 2 parts by weight of a curing catalyst (SRX212 containing a platinum catalyst, manufactured by Toray Dow Corning), and a toluene / hexane mixed solvent (volume ratio 1:1) as a diluent. The concentration of silicone solids in the mold release agent composition was 1.0% by weight. Next, the mold release agent composition was applied to one side of a liner substrate (Lumirror XD500P polyester film, 75 μm thick) using a wire bar, and heated at 130°C for 1 minute to produce a release liner A with a release layer (60 nm thick) on one side.

[0145] [Peel-off Liner B] A peelable liner B was prepared using the same method as peelable liner A, except that the thickness of the release agent composition applied to the liner substrate was changed, and a release layer (120 nm thick) was provided on one side.

[0146] [Monomer Syrup A1] Four flasks were prepared by adding 95.2 parts by weight of n-butyl acrylate (BA), 4.8 parts by weight of acrylic acid (AA), and 0.05 parts by weight of 1-hydroxycyclohexyl phenyl ketone (Omnirad 184, manufactured by IGM Resins BV) and 0.05 parts by weight of 2,2-dimethoxy-1,2-diphenylethane-1-one (Omnirad 651, manufactured by IGM Resins BV) as photopolymerization initiators. These flasks were then irradiated with ultraviolet light under a nitrogen atmosphere to obtain partially photopolymerized monomer syrup A1. The ultraviolet irradiation was continued until the viscosity of the liquid in the flask (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30°C) reached approximately 20 Pa·s.

[0147] [Monomer Syrup A2] Monomer syrup A2 was prepared using the same method as monomer syrup A1, except that the monomers used were changed as shown in Table 1.

[0148] [Table 1]

[0149] The abbreviations used in Table 1 are as follows: BA: n-butyl acrylate AA: Acrylic acid HBA: 4-hydroxybutyl acrylate

[0150] [Photocurable composition C1~C6] Next, monomer syrup, crosslinking agent, and rework improver were mixed to obtain photocurable compositions C1 to C6, as shown in Table 2 below.

[0151] [Table 2]

[0152] The abbreviations used in Table 2 are as follows: NDDA:1,9-nonanediol diacrylate D376N: Isocyanurate-modified form of pentamethylene diisocyanate (manufactured by Mitsui Chemicals, Inc., Stabio D-376N) SAT10: A polyether compound containing an alkoxysilyl group (manufactured by Kaneka Corporation, Cyryl SAT10). 9591F: Acid anhydride group-containing oligomer-type silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., X-24-9591F) 1056: Epoxy group-containing oligomer-type silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., X-41-1056)

[0153] (Example 1) A photocurable composition C1 was applied to the surface of the release layer of the release liner A using an applicator to form a coated layer (20 μm thick). Next, the above-mentioned release liner B was placed on the formed coated layer to obtain the first laminate. The release liner B was positioned so that its release layer was in contact with the coated layer. Next, an illuminance of 2.5 mW / cm² was applied from the side of the release liner A in the first laminate. 2 The coated layer was photocured by irradiating it with ultraviolet light (black light source) for 640 seconds, forming a second laminate consisting of a release liner A, an adhesive sheet (20 μm thick), and a release liner B.

[0154] Next, the release liner B was peeled off the second laminate, and the polarizing film described above was placed on the exposed surface of the adhesive sheet to obtain the optical laminate of Example 1. The polarizing film was positioned so that the surface of the transparent protective film made of a modified acrylic polymer was in contact with the adhesive sheet.

[0155] (Example 2) The release liner B was peeled off from the second laminate, and a discharge rate of 61 W / m was applied to the exposed surface of the adhesive sheet. 2The optical laminate of Example 2 was obtained by the same method as in Example 1, except that corona treatment was performed at min and then a polarizing film was placed on the exposed surface.

[0156] (Examples 3-6) Optical laminates of Examples 3 to 6 were obtained by the same method as in Example 2, except that the photocurable composition used was changed as shown in Table 3.

[0157] (Example 7) The optical laminate of Example 7 was obtained by the same method as in Example 1, except that the photocurable composition used was changed as shown in Table 3.

[0158] (Comparative Example 1) The optical laminate of Comparative Example 1 was obtained by the same method as in Example 6, except that corona treatment was not performed on the exposed surface of the adhesive sheet.

[0159] (Comparative Example 2) The optical laminate of Comparative Example 2 was obtained by the same method as in Example 4, except that corona treatment was not performed on the exposed surface of the adhesive sheet.

[0160] (Comparative Example 3) The optical laminate of Comparative Example 3 was obtained by the same method as in Example 5, except that corona treatment was not performed on the exposed surface of the adhesive sheet.

[0161] [Anchoring power] The anchoring force F between the adhesive sheet and the polarizing film was measured for the optical laminates of the examples and comparative examples using the method described above. The double-sided tape used was "No. 531," manufactured by Nitto Denko Corporation. A SUS304 plate (40mm wide x 120mm long) was used as the stainless steel test plate. ITO film (125 Tetrilite OES, manufactured by Oike Kogyo Co., Ltd.) was used as the evaluation sheet. A Shimadzu Autograph AG-I 10KN tensile testing machine was used.

[0162] [Adhesive strength] The adhesive strengths P0 and P1 were measured for the optical laminates of the examples and comparative examples by performing tests 1 and 2 described above. Tests 1 and 2 used alkali-free glass with a thickness of 0.7 mm (Corning, product name "EG-XG"). The operation of peeling the test specimen from the alkali-free glass was performed using a tensile testing machine (Shimadzu Corporation, Autograph SHIMAZU AG-1 10KN).

[0163] [Durability] The durability (85°C durability) of the optical laminates of the examples and comparative examples was evaluated by the following method. First, the optical laminate was cut into strips measuring 300 mm in length and 220 mm in width to prepare test specimens. Next, the test specimens were attached to the surface of 0.7 mm thick alkali-free glass (Corning, product name "EG-XG") using an adhesive sheet. The test specimens were attached to the alkali-free glass using a laminator. After attaching the test specimens, they were placed in an autoclave at 50°C and 0.5 MPa for 15 minutes to homogenize the bond between the alkali-free glass and the adhesive sheet, and to ensure that the adhesive sheet adhered tightly to the alkali-free glass. Next, the test specimens were heat-treated at 85°C for 500 hours under atmospheric pressure. The appearance of the adhesive sheet between the polarizing film and the alkali-free glass was visually observed, and the durability of the adhesive sheet was evaluated according to the following criteria. (Evaluation Criteria) A: There are absolutely no visible changes such as foaming or peeling. B: There are minor peeling or foaming of 0.3 mm or less at the edges, but this does not affect practical use. C: There is peeling or foaming of 1 mm or less at the edges. D: There is peeling of more than 1 mm at the edge.

[0164] Furthermore, durability (95°C durability) was evaluated using the same method and evaluation criteria as above, except that the heat treatment conditions were changed to 95°C for 500 hours.

[0165] [Table 3]

[0166] As can be seen from Table 3, the optical laminate of the example, in which the anchoring force F between the adhesive sheet and the optical film (polarizing film) was 10.0 N / 25 mm or more, showed better durability at 85°C compared to the comparative example. Furthermore, in the optical laminate of the example, almost no peeling was observed between the polarizing film and the adhesive sheet even when the durability was evaluated at 95°C. Thus, since peeling between the polarizing film and the adhesive sheet is suppressed in the optical laminate of the example, it is presumed that this optical laminate can suppress problems with the image display function of image display devices.

[0167] Furthermore, as can be seen from Table 3, Examples 4 and 5 also showed good durability at 95°C. These laminates are particularly suitable for applications requiring durability in high-temperature environments, such as automotive applications. [Industrial applicability]

[0168] The optical laminate of the present invention can be used, for example, in an image display device. [Explanation of Symbols]

[0169] 1 Adhesive sheet 2 Optical film 10,11 Optical laminate

Claims

1. An adhesive sheet formed from a photocurable composition having a solvent content of 5% by weight or less, An optical film comprising at least one selected from the group consisting of polarizing films and phase difference films, Equipped with, The photocurable composition comprises a group of monomers including (meth)acrylic monomers and / or a partial polymer of the monomer group, The anchoring force between the adhesive sheet and the optical film is 10.0 N / 25 mm or more and 50 N / 25 mm or less. The adhesive sheet is an optical laminate having a surface that faces the optical film and has been subjected to a surface modification treatment.

2. The optical laminate according to claim 1, wherein the anchoring force is greater than 16.0 N / 25 mm.

3. An adhesive sheet formed from a photocurable composition having a solvent content of 5% by weight or less, An optical film comprising at least one selected from the group consisting of polarizing films and phase difference films, Equipped with, The photocurable composition comprises a group of monomers including (meth)acrylic monomers and / or a partial polymer of the monomer group, The anchoring force between the adhesive sheet and the optical film is 10.0 N / 25 mm or more and 50 N / 25 mm or less. The adhesive strength P was determined by the following test. 0 An optical laminate having a density of 8.0 N / 25 mm or less. Test: The adhesive sheet is attached to alkali-free glass, and the adhesive sheet is peeled off the alkali-free glass at a peeling speed of 300 mm / min and a peeling angle of 90°. The force required at this time (adhesive force P) 0 ) Measure.

4. The adhesive force P 0 The optical laminate according to claim 3, wherein the N / 25 mm is 0.5 to 7.0 N.

5. The anchoring force and the adhesive force P 0 The optical laminate according to claim 3, wherein the difference between the two is 5.0 N / 25 mm or more.

6. An adhesive sheet formed from a photocurable composition having a solvent content of 5% by weight or less, An optical film comprising at least one selected from the group consisting of polarizing films and phase difference films, Equipped with, The photocurable composition comprises a group of monomers including (meth)acrylic monomers and / or a partial polymer of the monomer group, The anchoring force between the adhesive sheet and the optical film is 10.0 N / 25 mm or more and 50 N / 25 mm or less. The adhesive strength P was determined by the following test. 1 An optical laminate having a density of 10.0 N / 25 mm or more. Test: The adhesive sheet is attached to alkali-free glass and heat-treated at 60°C for 100 hours. The adhesive sheet is peeled off the alkali-free glass at a peeling speed of 300 mm / min and a peeling angle of 90°. The force required at this time (adhesive force P) 1 ) Measure.

7. The adhesive sheet has a surface facing the optical film, The optical laminate according to claim 1, wherein when the surface is treated with trifluoroethanol, the elemental ratio R of fluorine on the surface is 0.1 atomic percent or more.

8. The optical laminate according to claim 1, wherein the optical film faces the adhesive sheet and has a surface that has been subjected to a surface modification treatment.

9. The optical laminate according to claim 1, wherein the monomer group includes a carboxyl group-containing monomer.

10. The optical laminate according to claim 1, wherein the monomer group includes an ether group-containing monomer.

11. The optical laminate according to claim 1, wherein the photocurable composition comprises a rework improver.

12. The optical laminate according to claim 11, wherein the rework enhancer is a silane coupling agent.

13. The optical laminate according to claim 1, wherein the photocurable composition comprises an isocyanate-based crosslinking agent.

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