TW202411376A - Optical layered body - Google Patents

Abstract

The present invention provides an optical layered body which is capable of suppressing the occurrence of problems in the image display function of an image display device. An optical layered body according to the present invention is equipped with an adhesive sheet 1 formed from a photocurable composition, and an optical film 2 which includes one or more films selected from the group consisting of a polarizing film and a phase difference film. The anchoring force F between the adhesive sheet 1 and the optical film 2 is 10.0N/25mm or higher. The anchoring force F may be greater than 16.0N/25mm.

Description

Optical laminate

The present invention relates to an optical multilayer.

Various image display devices represented by liquid crystal display devices and electroluminescent (EL) display devices generally have an optical laminate including an optical film such as a polarizing film and an adhesive sheet. The optical films contained in the optical laminate or the optical laminate and the image display panel are usually bonded using an adhesive sheet. Typically, a sheet formed by curing a monomer group containing an acrylic monomer or a polysilicone monomer by polymerization and crosslinking is used as the adhesive sheet.

Patent document 1 discloses an example of an adhesive sheet. In Patent document 1, the adhesive sheet is produced by irradiating light to an adhesive composition. Prior art document Patent document

Patent document 1: Japanese Patent No. 3052972

Problem to be solved by the invention General adhesive sheets can be manufactured by, for example, the following heat curing method. First, a crosslinking agent is mixed into a polymer produced by polymerizing a polymerizable monomer in an organic solvent to prepare an adhesive composition. The adhesive composition is applied to a substrate such as a peeling liner, and the organic solvent is removed by heating to form a sheet. Heat aging is performed as required to complete the crosslinking, thereby manufacturing an adhesive sheet. In this process, in order to generate the heat energy required for heating to remove the solvent or heat aging, a large amount of fuel such as LNG must be burned. In addition, if the organic solvent that has been removed by heat is released directly, there is a risk of significant adverse effects on the surrounding environment. Therefore, for organic solvents, most of them are released after being burned in a deodorizer or the like. At this time, the process not only requires more fuel for combustion in the deodorizing furnace, but the organic solvent itself will also be converted into _CO2 and released into the atmosphere through combustion, resulting in extremely large _CO2 emissions.

In recent years, climate change caused by greenhouse gases has become an urgent issue, and governments around the world have raised numerical targets and worked hard to reduce CO _2. In the manufacture of adhesive sheets, it is also required to select a process that does not use organic solvents and has low CO ₂ emissions.

Compared to the above-mentioned heat curing method, if the method of making the adhesive sheet using light (photocuring method) is used, the amount of energy required to form the adhesive sheet or the amount of CO ₂ emissions can be further reduced. However, when an optical multilayer body is made using an adhesive sheet formed by the photocuring method, there is a tendency for the image display function of the image display device having the optical multilayer body to have problems with long-term use. This problem occurs particularly significantly when it is repeatedly used in a high temperature environment.

Therefore, an object of the present invention is to provide an optical multilayer body that can suppress problems in the image display function of an image display device.

Means for solving the problem According to the research of the inventors, when using an adhesive sheet formed by a photocuring method, there is a tendency for peeling to occur between the adhesive sheet and the optical film, compared with the case of using an adhesive sheet formed by a heat curing method. We speculate that this tendency is because when the adhesive sheet formed by a heat curing method is bonded to the optical film, the adhesive sheet will further cure on the surface of the optical film; on the other hand, the adhesive sheet formed by a photocuring method will hardly cure after being bonded to the optical film. This problem is particularly prominent when the optical film includes a uniaxially stretched film such as a polarizer or when the thickness of the adhesive sheet is less than 30µm.

If the adhesive sheet and the optical film peel off, not only will air intrude therebetween, but the optical film may also deviate from the proper position. This may cause problems in the image display function of the image display device. The inventors of the present invention have conducted research based on the above insights and have completed the present invention.

The present invention provides an optical laminate, comprising: an adhesive sheet formed of a photocurable composition; and an optical film comprising at least one selected from the group consisting of a polarizing film and a phase difference film; and the anchoring force between the adhesive sheet and the optical film is above 10.0N/25mm.

Effect of the invention According to the present invention, an optical multilayer body can be provided, which can suppress problems in the image display function of an image display device.

The optical laminate of the first aspect of the present invention comprises: an adhesive sheet formed of a photocurable composition; and an optical film comprising at least one selected from the group consisting of a polarizing film and a phase difference film; and the anchoring force between the adhesive sheet and the optical film is above 10.0N/25mm.

Regarding the second aspect of the present invention, for example, in the optical layered structure of the first aspect, the anchoring force is greater than 16.0N/25mm.

Regarding the third aspect of the present invention, for example, the optical laminate of the first or second aspect has a bonding force _P0 of 8.0 N/25 mm or less obtained by the following test; Test: The adhesive sheet is attached to an alkali-free glass, and the adhesive sheet 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 (bonding force _P0 ) is measured.

Regarding the fourth aspect of the present invention, for example, in the optical laminate of the third aspect, the aforementioned adhesion force _P0 is 0.5~7.0N/25mm.

Regarding the fifth aspect of the present invention, for example, in the optical multilayer of the third or fourth aspect, the difference between the anchoring force and the contact force P ₀ is greater than 5.0 N/25 mm.

Regarding the sixth aspect of the present invention, for example, the optical laminate of any one of the first to fifth aspects has a bonding force _P1 of 10.0 N/25 mm or more obtained by the following test; Test: The adhesive sheet is attached to an alkali-free glass and heat-treated at 60° C. for 100 hours; the adhesive sheet is peeled off from the alkali-free glass at a peeling speed of 300 mm/min and a peeling angle of 90°; and the force required at this time (bonding force _P1 ) is measured.

In a seventh aspect of the present invention, in the optical laminate of any one of the first to sixth aspects, the content of the solvent in the photocurable composition is 5 wt % or less.

Regarding the eighth aspect of the present invention, for example, in the optical laminate of any one of the first to seventh aspects, the adhesive sheet has a surface that is opposite to the optical film and has been subjected to a surface modification treatment.

Regarding the 9th aspect of the present invention, for example, in the optical laminate of any one of the 1st to 8th aspects, the adhesive sheet has a surface opposite to the optical film, and after the surface is treated with trifluoroethanol, the element ratio R of fluorine in the surface is greater than 0.1 atomic %.

Regarding the tenth aspect of the present invention, for example, in the optical laminate of any one of the first to ninth aspects, the optical film has a surface that is opposite to the adhesive sheet and has been subjected to a surface modification treatment.

Regarding the 11th aspect of the present invention, for example, in the optical laminate of any one of the 1st to 10th aspects, the aforementioned photocurable composition comprises a monomer group containing a (meth)acrylic monomer and/or a partial polymer of the aforementioned monomer group.

Regarding the twelfth aspect of the present invention, for example, in the optical layer of the eleventh aspect, the monomer group includes a carboxyl group-containing monomer.

Regarding the 13th aspect of the present invention, for example, in the optical layered structure of the 11th or 12th aspect, the monomer group includes ether group-containing monomers.

In a fourteenth aspect of the present invention, in the optical laminate of any one of the first to thirteenth aspects, the photocurable composition includes a rework enhancer.

Regarding the 15th aspect of the present invention, for example, in the optical layered structure of the 14th aspect, the aforementioned heavy-duty enhancing agent is a silane coupling agent.

In a sixteenth aspect of the present invention, in the optical laminate of any one of the first to fifteenth aspects, the photocurable composition comprises an isocyanate crosslinking agent.

The present invention is described in detail below, but the present invention is not limited to the following implementation forms and can be arbitrarily modified and implemented within the scope of the gist of the present invention.

[Implementation form of optical laminate] An example of an optical laminate of this implementation form is shown in FIG1. The optical laminate 10 of FIG1 includes: an adhesive sheet 1, which is formed of a photocurable composition; and an optical film 2, which is at least one selected from the group consisting of a polarizing film and a phase difference film. The adhesive sheet 1 is preferably directly connected to the optical film 2. The optical laminate 10 may also have a structure in which a base sheet used in making the adhesive sheet 1 is laminated on the adhesive sheet 1. The optical laminate 10 can be used as an optical film attached to an adhesive sheet.

The anchoring force F between the adhesive sheet 1 and the optical film 2 is 10.0 N/25 mm or more. When the anchoring force F is as large as this, peeling between the adhesive sheet 1 and the optical film 2 can be suppressed, thereby suppressing the image display function of the image display device from causing problems.

The anchoring force F of the adhesive sheet 1 and the optical film 2 can be measured by the following method. First, cut the optical laminate 10 to be evaluated into a sample piece with a width of 25 mm and a length of 150 mm. Then, the entire surface of the optical film 2 of the sample piece is superimposed on a stainless steel test plate using a double-sided adhesive tape, and a 2 kg roller is passed back and forth once to press them together. Then, the adhesive sheet 1 of the test piece is superimposed on the evaluation sheet, and a 2 kg roller is passed back and forth once to press them together. There is no particular limitation on the evaluation sheet as long as it has a size of 30 mm wide and 150 mm long and does not peel off from the adhesive sheet 1 during the test. The evaluation sheet can be, for example, an ITO film (125 TETOLIGHT OES (manufactured by Oike Industries)). Next, using a commercially available tensile tester, the adhesive sheet 1 is peeled off from the optical film 2 at a peeling angle of 180° and a tensile speed of 300 mm/min while holding the evaluation sheet, and the average value of the peeling force at this time is determined as the anchoring force F of the adhesive sheet 1 and the optical film 2. In addition, the above test is performed in a gas environment at 23°C.

The anchoring force F between the adhesive sheet 1 and the optical film 2 is preferably 11.0 N/25 mm or more, and 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 may be 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.

(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 to the outside of the optical laminate 10, for example. Surface 1a of the adhesive sheet 1 may or may not be subjected to surface modification. If the surface 1a subjected to surface modification is used, there is a tendency to increase the above-mentioned anchoring force F. Surface 1b of the adhesive sheet 1 is preferably not subjected to surface modification. The surface modification treatment may include corona treatment, plasma treatment, excimer treatment, flame treatment, etc. Surface 1a is preferably subjected to corona treatment as the surface modification treatment.

The surface modification treatment can also be carried out in an inert gas environment. By carrying out the surface modification treatment in a state where the oxygen concentration is reduced by using an inert gas, the risk of fire to the residual monomer can be reduced. Specifically, the surface modification treatment should be carried out at an oxygen concentration of 8 volume % or less. It is more preferably 6 volume % or less, and more preferably 3 volume % or less. If the oxygen concentration is too low, there will be a situation where insufficient functional groups are introduced into the surface of the adhesive sheet through the surface modification treatment. Therefore, the oxygen concentration should be 0.01 volume % or more, more preferably 0.1 volume % or more, and particularly preferably 0.5 volume % or more. Specific examples of inert gases include nitrogen or argon. The surface modification treatment can also be carried out under normal pressure (1 atmosphere).

The conditions of the surface modification treatment of the corona treatment are expressed by the discharge amount, for example, 0.6~100kJ/m ^2. The lower limit of the discharge amount may be 1kJ/m ² or more, 2kJ/m ² or more, 5kJ/m ² or more, 7kJ/m ² or more, 10kJ/m ² or more, 13kJ/m ² or more, 15kJ/m ² or more, 20kJ/m ² or more, 25kJ/m ² or more, 30kJ/m ² or more, and may be 35kJ/m ² or more. The upper limit of the discharge amount may be 70kJ/m ² or less, 60kJ/m ² or less, 50kJ/m ² or less, 45kJ/m ² or less, 40kJ/m ² or less, 30kJ/m ² or less, 20kJ/m ² or less, and may be 18kJ/m ² or less. When the corona treatment is carried out in a gas environment with an oxygen concentration of 10 volume % or more and 20.9 volume % or less, the discharge amount can also be 1~18 kJ/m ² . When the corona treatment is carried out in a gas environment with an oxygen concentration of 0.01 volume % or more and less than 10 volume %, the discharge amount can also be 1~60 kJ/m ² . By appropriately adjusting the discharge amount of the corona treatment, there is a tendency to further increase the above-mentioned anchoring force F.

After the surface 1a of the adhesive sheet 1 is treated with trifluoroethanol, the element ratio R of fluorine in the surface 1a is preferably large. The element ratio R is, for example, 0.1 atomic % or more, or 0.2 atomic % or more, 0.3 atomic % or more, or even 0.4 atomic % or more. The upper limit of the element ratio R is, for example, 1.0 atomic % or less.

The element ratio R can be determined by the following method. First, prepare an adhesive sheet 1 cut into 10 mm in length and 10 mm in width, and adhere the adhesive sheet 1 to the inner wall of the sample tube in a manner that the surface 1a is exposed. Add trifluoroethanol (TFE) to the sample tube, and allow the vaporized TFE to contact the adhesive sheet 1. In this way, the surface 1a can be treated with TFE. By treating with TFE, the carboxyl groups present on the surface 1a react with TFE, and the carboxyl groups are chemically modified. The reaction between the carboxyl groups and TFE can be expressed by the following formula. In addition, the amount of TFE to be added to the sample tube is adjusted so that all the carboxyl groups present on the surface 1a can react with TFE. R-COOH + CF ₃ CH ₂ OH → R-COOCH ₂ CF ₃

Next, the adhesive sheet 1 treated with TFE is taken out from the sample tube and placed in an X-ray photoelectron spectrometer. Using the X-ray photoelectron spectrometer, the surface 1a of the adhesive sheet 1 is subjected to a wide spectrum scanning measurement for qualitative analysis. In this way, the elements present on the surface 1a are identified. Next, a narrow spectrum scanning measurement is performed on each element present on the surface 1a. Based on the results of the narrow spectrum scanning measurement, the element ratio R of fluorine in the surface 1a can be determined. In addition, the fluorine on the surface 1a typically originates from TFE after reacting with carboxyl groups. Therefore, the element ratio R1 can be used as an indicator of the amount of carboxyl groups present on the surface 1a before treatment with TFE. The larger the element ratio R, the greater the amount of carboxyl groups present on the surface 1a, and there is a tendency to increase the above-mentioned anchoring force F. Furthermore, according to the research of the inventors, when the surface 1a has been subjected to surface modification treatment, there is a tendency for the element ratio R to increase.

As mentioned above, the adhesive sheet 1 is formed by a photocurable composition. The photocurable composition is an adhesive composition that forms the adhesive sheet 1 by irradiating light. The photocurable composition, for example, includes a monomer group containing a (meth)acrylic monomer and/or a partial polymer of the monomer group. The content of the (meth)acrylic component in the photocurable composition, that is, the (meth)acrylic monomer and its partial polymer, can be more than 50 weight %, more than 60 weight %, more than 70 weight %, and can even be more than 80 weight %, at this time, an acrylic adhesive sheet 1 with (meth)acrylic polymer and its cross-linked product as the main component can be formed. However, the photocurable composition is not limited to the above examples. In this specification, (meth)acrylic acid means acrylic acid and methacrylic acid. (Meth)acrylate means acrylate and methacrylate.

An example of a (meth)acrylic acid monomer is an alkyl (meth)acrylate having an alkyl group with 1 to 20 carbon atoms in the side chain. The carbon number of the alkyl group may be 7 or less, 6 or less, 5 or less, or even 4 or less. The alkyl group may be a straight chain or may have a branched chain. Examples of the alkyl (meth)acrylates are methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, dibutyl (meth)acrylate, tertiary butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 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, heptadecanyl (meth)acrylate, and octadecyl (meth)acrylate. The alkyl (meth)acrylate may also be n-butyl (meth)acrylate.

The blending amount of the alkyl (meth)acrylate in 100 parts by weight of the monomer group is, for example, 40 parts by weight or more, or 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. In addition, when calculating the blending amount of a specific monomer, the weight of a portion of the polymer is converted to the weight of each monomer before polymerization.

The monomer group may also include a carboxyl-containing monomer. The carboxyl-containing monomer may be a (meth)acrylic acid-based monomer. In other words, the (meth)acrylic acid-based monomer may also include a carboxyl-containing monomer. Examples of carboxyl-containing monomers are (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. In 100 parts by weight of the monomer group, the blending amount of the carboxyl-containing monomer is, for example, less than 10 parts by weight, and may also be less than 9 parts by weight, less than 8 parts by weight, less than 7 parts by weight, less than 6 parts by weight, less than 5 parts by weight, less than 4.8 parts by weight, less than 4 parts by weight, less than 3 parts by weight, less than 2 parts by weight, less than 1 part by weight, and may even be less than 0.5 parts by weight. The lower limit of the blending amount is, for example, more than 0.1 parts by weight, and may also be more than 0.5 parts by weight depending on the circumstances. The monomer group may also not contain a carboxyl-containing monomer.

The monomer group may also include a hydroxyl-containing monomer. The hydroxyl-containing monomer may be a (meth)acrylic monomer, in other words, the (meth)acrylic monomer may also include a hydroxyl-containing monomer. The hydroxyl-containing monomer may help to enhance the cohesive force of the adhesive sheet. Examples of hydroxyl-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)-methacrylate. The hydroxyl-containing monomer is preferably 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate. The blending amount of the hydroxyl-containing monomer in 100 parts by weight of the monomer group is, for example, 20 parts by weight or less, and may also 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, and may further be 0.5 parts by weight or less. The lower limit of the blending amount is, for example, 0.01 parts by weight or more, and may also be 0.03 parts by weight or more, and may further be 0.05 parts by weight or more. The monomer group may also not contain a hydroxyl-containing monomer.

The monomer group may also include an ether group-containing monomer. The ether group-containing monomer may be a (meth)acrylic monomer. In other words, the (meth)acrylic monomer may also include an ether group-containing monomer. The ether group-containing monomer may help to improve the above-mentioned anchoring force F.

The ether group-containing monomer is preferably an alkoxy group-containing monomer. As the alkoxy group-containing monomer, an alkylene oxide adduct represented by the following chemical formula (1) can be cited. R ¹ in formula (1) is a hydrogen atom or a methyl group. R ² in formula (1) is an alkyl group. The alkyl group may be a linear chain or may have a branched chain. R ² is preferably a linear chain alkyl group. Examples of R ² are methyl and ethyl. n in formula (1) is an integer of 1 to 30, preferably an integer of 1 to 12, and may also be an integer of 1 to 5. [Chemical formula 1]

Examples of the alkylene oxide adduct represented by 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).

The ether group-containing monomer is not limited to the above-mentioned alkylene oxide adduct. The ether group-containing monomer may have a ring structure, and the ring structure may also have an ether group. Examples of the ring structure having an ether group include tetrahydrofuran ring, dioxane, etc. Examples of the ether group-containing monomer having a ring structure are cyclic trihydroxymethylpropane formal (meth) acrylate and tetrahydrofurfuryl (meth) acrylate.

The blending amount of the ether group-containing monomer in 100 parts by weight of the monomer group is, for example, 1 part by weight or more, and may also 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 may further be 90 parts by weight or more. The upper limit of the blending amount is, for example, 99 parts by weight or less, and may be 50 parts by weight or less depending on the circumstances. The monomer group may not contain the ether group-containing monomer.

In the photocurable composition, each of the above monomers may also be contained as a partial polymer. The partial polymer may be any of a homopolymer and a copolymer. The partial polymer will appropriately increase the viscosity of the photocurable composition, thereby contributing to the stable formation of the coating layer described later.

The photocurable composition usually contains a photopolymerization initiator. Examples of the photopolymerization initiator are photoradical generators that generate free radicals using visible light and/or ultraviolet light having a wavelength shorter than 450 nm.

Examples of photopolymerization initiators include benzoin ethers such as benzoin methyl ether, benzoin isopropyl ether, and benzyl dimethyl ketal; substituted benzoin ethers such as anisole methyl ether; substituted acetophenones such as 2,2-diethoxyacetophenone and 2,2-dimethoxy-2-phenylacetophenone; α-hydroxyalkyl phenones such as 1-hydroxycyclohexyl-phenyl ketone; substituted α-keto alcohols such as 2-methyl-2-hydroxypropiophenone; aromatic Sulfonyl chloride; optically active oximes such as 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime; diphenyl ketone compounds such as diphenyl ketone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenyldiphenyl ketone, hydroxydiphenyl ketone, acrylated diphenyl ketone, 4-benzoyl-4'-methyl diphenyl sulfide, 3,3',4,4'-tetrakis(tertiary butylperoxycarbonyl)diphenyl ketone; 9-oxysulfuron , 2-chloro-9-oxysulfuron , 2-methyl 9-oxosulfuron 、Isopropyl 9-oxysulfide 、2,4-Diisopropyl 9-oxysulfide , 2,4-diethyl 9-oxysulfide 9-Oxysulfuron Series compounds; 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-tolyl)-4,6-bis(trichloromethyl)-s-triazine, 2-piperonyl (piperonyl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-bis(trichloromethyl)-6-phenylvinyl-s-triazine, 2-(naphthoyl-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxy-naphthoyl-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-trichloromethyl-(piperonyl)-6 -trioxane, 2,4-trichloromethyl-(4'-methoxyphenyl)-6-trioxane, etc. trioxane compounds; 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], O-(acetyl)-N-(1-phenyl-2-oxo-2-(4'-methoxy-naphthyl)ethylidene)hydroxylamine, etc. phosphine compounds such as bis(2,4,6-trimethylbenzyl)phenylphosphine oxide and 2,4,6-trimethylbenzyldiphenylphosphine oxide; quinone compounds such as 9,10-phenanthrenequinone, camphorquinone, ethylanthraquinone; borate compounds; carbazole compounds; imidazole compounds; and, titaniumocene compounds. The photocurable composition may also contain one or more photopolymerization initiators.

The amount of the photopolymerization initiator in the photocurable composition is, for example, 0.02 to 10 parts by weight, or 0.05 to 5 parts by weight, relative to 100 parts by weight of the total monomer group and its partial polymer.

The photocurable composition may also contain a crosslinking agent. An example of a crosslinking agent is a multifunctional monomer having two or more polymerizable functional groups in one molecule. The multifunctional monomer may also be a (meth)acrylic monomer. Examples of multifunctional monomers are: a monomer having two or more C=C bonds in one molecule, and a monomer having one or more C=C bonds and one or more polymerizable functional groups such as epoxy, azoxy, oxazolinyl, hydrazine, hydroxymethyl, etc. in one molecule. The multifunctional monomer is preferably a monomer having two or more C=C bonds in one molecule.

Examples of the multifunctional monomer 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, 1,9-nonanediol diacrylate (NDDA), 1,12-dodecanediol di(meth)acrylate, trihydroxymethylpropane tri(meth)acrylate, tetrahydroxymethylmethane tri(meth)acrylate and other multifunctional acrylates (ester compounds of polyols and (meth)acrylic acid, etc.); allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di(meth)acrylate, hexyl di(meth)acrylate. The multifunctional monomer is preferably a multifunctional acrylate, more preferably trihydroxymethylenepropane tri(meth)acrylate, hexanediol di(meth)acrylate, or dipentatriol hexa(meth)acrylate.

The crosslinking agent may also include other crosslinking agents other than the above-mentioned multifunctional monomer. Examples of other crosslinking agents include isocyanate crosslinking agents. The photocurable composition may include an isocyanate crosslinking agent as a crosslinking agent, preferably including both the above-mentioned multifunctional monomer and the isocyanate crosslinking agent as crosslinking agents. The isocyanate crosslinking agent may help to improve the above-mentioned anchoring force F.

The isocyanate crosslinking agent may be a compound having at least two isocyanate groups (isocyanate compound). The number of isocyanate groups contained in the isocyanate compound is preferably 3 or more. The upper limit of the number of isocyanate groups is not particularly limited, and is, for example, 5. Examples of the isocyanate compound include aromatic isocyanate compounds, alicyclic isocyanate compounds, aliphatic isocyanate compounds, and the like.

Examples of the aromatic isocyanate compounds include phenyl diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, and stilbene diisocyanate.

Examples of the alicyclic isocyanate compounds include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated stilbene diisocyanate, hydrogenated methylene diisocyanate, hydrogenated tetramethyl stilbene diisocyanate, and the like.

Aliphatic isocyanate compounds include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate (PDI), 1,2-propyl diisocyanate, 1,3-butyl diisocyanate, dodecamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and the like.

Isocyanate crosslinking agents may also include: polymers (dimers, trimers, pentamers, etc.) of the above-mentioned isocyanate compounds, adducts obtained by adding to polyols such as trihydroxymethylpropane, urea modifications, biuret modifications, allophanate modifications, isocyanurate modifications, carbodiimide modifications, urethane prepolymers obtained by adding to polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, etc., and the like.

The isocyanate crosslinking agent preferably includes an aliphatic isocyanate compound and/or a derivative of an aliphatic isocyanate compound. The isocyanate crosslinking agent is preferably 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 modified isocyanurates of PDI, etc. Specific examples of HDI crosslinking agents include modified isocyanurates of HDI or biuret modified products, etc.

The amount of the crosslinking agent in the curable composition varies depending on the molecular weight or the number of functional groups, but is, for example, 5 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, relative to 100 parts by weight of the total of the monomer group and its partial polymer. The lower limit of the amount of the crosslinking agent is, for example, 0.01 parts by weight or more, or 0.05 parts by weight or more.

In addition, when the photocurable composition includes an isocyanate crosslinking agent, the amount of the isocyanate crosslinking agent blended is, for example, 0.02 parts by weight or more, 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, relative to 100 parts by weight of the total monomer group and its partial polymer. When the photocurable composition includes an isocyanate crosslinking agent, if the blending amount of the hydroxyl-containing monomer in the photocurable composition is adjusted to a smaller value, there is a tendency to further increase the anchoring force F.

When an isocyanate crosslinking agent is added, the adhesive sheet may become hard, especially in a high temperature environment. At this time, the stress relaxation of the adhesive sheet will be damaged, so the expansion or contraction stress of the optical film will be easily transmitted to the interface between the adhesive sheet and the adherend, and there is a tendency to peel off easily. When means other than adding an isocyanate crosslinking agent can be used to ensure the anchoring force between the adhesive sheet and the optical film, the photocurable composition preferably does not contain an isocyanate crosslinking agent.

The photocurable composition may further include a reweighting agent. The reweighting agent is a component that, when the adhesive sheet 1 is attached to an adherend such as alkali-free glass or a transparent conductive layer, segregates on the surface of the adherend to reduce the adhesion (such as adhesion force P ₀ described below) between the adhesive sheet 1 and the adherend.

The heavy lifting agent may be, for example, a silane coupling agent having an alkoxysilyl group, preferably having an alkoxysilyl group and a polar group. In the heavy lifting agent, specific examples of the alkoxy group contained in the alkoxysilyl group are methoxy group, ethoxy group, etc. Polar groups include, for example, carboxyl group, acid anhydride group, epoxy group, etc. The carboxyl group may also be a group generated by hydrolysis of an acid anhydride group. Examples of the acid anhydride group include carboxylic anhydride groups such as succinic anhydride group, phthalic anhydride group, and maleic anhydride group. The heavy lifting agent may have an ether group other than an epoxy group, and may also have a polyether skeleton.

The re-working agent preferably has at least one selected from the group consisting of anhydride groups and epoxy groups. When a re-working agent having anhydride groups or epoxy groups is used, the adhesive sheet 1 tends to increase the bonding strength (bonding strength P ₁ described below) between the adhesive sheet 1 and the glass by performing a heat treatment after the adhesive sheet 1 is attached to the alkali-free glass.

Examples of heavy lifting agents include alkoxysilane compounds having polar groups, organic polysiloxane compounds having polar groups and alkoxysilane groups, and polyether compounds having alkoxysilane groups.

Examples of the alkoxysilane compound having a polar group include 2-trimethoxysilylethylsuccinic anhydride, 3-trimethoxysilylpropylsuccinic anhydride (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X-12-967C"), 3-triethoxysilylpropylsuccinic anhydride, 3-methyldiethoxysilylpropylsuccinic anhydride, and 1-carboxy-3-triethoxysilylpropylsuccinic anhydride.

Examples of the organopolysiloxane compound having a polar group and an alkoxysilyl group include an oligomer silane coupling agent containing an acid anhydride group (trade name "X-24-9591F"), an oligomer silane coupling agent containing an epoxy group (trade names "X-41-1053", "X-41-1059A", "X-41-1056", "X-40-2651", etc.) manufactured by Shin-Etsu Chemical Co., Ltd.

Examples of polyether compounds having an alkoxysilyl group include MS polymer S203, S303, S810, SILYL EST250, EST280, SAT10, SAT200, SAT220, SAT350, SAT400 manufactured by Kaneka Corporation, and EXCESTAR S2410, S2420, S3430 manufactured by Asahi Glass Co., Ltd.

In the photocurable composition, the amount of the heavy-duty enhancer blended is, for example, 0.01 parts by weight or more, or 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, relative to 100 parts by weight of the total monomer group and its partial polymer. The upper limit of the blending amount is, for example, 10 parts by weight or less, or 5 parts by weight or less, or even 1 part by weight or less. The photocurable composition may not contain a heavy-duty enhancer.

The photocurable composition may also contain additives other than those mentioned above. Examples of additives are: chain transfer agents, silane coupling agents other than heavy lifting agents, viscosity modifiers, tackifiers, plasticizers, softeners, anti-aging agents, fillers, colorants, antioxidants, surfactants, antistatic agents, and ultraviolet absorbers.

The content of the solvent in the photocurable composition is, for example, 5 wt % or less, and may also be 4 wt % or less, 3 wt % or less, 2 wt % or less, 1 wt % or less, or even 0.5 wt % or less. The photocurable composition may be substantially free of solvent. The term "substantially free of solvent" means that the content of solvent derived from additives, etc., is allowed to be, for example, 0.1 wt % or less, preferably 0.05 wt % or less, and more preferably 0.01 wt % or less.

The viscosity of the photocurable composition is preferably 5 to 150 poise. The photocurable composition having a viscosity within the above range is particularly suitable for forming the coating layer described below.

The polymerization rate of the monomer group of the adhesive sheet 1 is preferably 90% or more. The polymerization rate may also be 95% or more, 98% or more, or even 99% or more.

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

The latent variable of the adhesive sheet 1 is, for example, less than 500 µm, and may also be less than 300 µm, less than 180 µm, less than 160 µm, less than 150 µm, less than 100 µm, or more than 50 µm. The lower limit of the latent variable is, for example, greater than 5 µm, and may also be greater than 10 µm, or more than 20 µm.

The latent variable of the adhesive sheet 1 can be evaluated in the following manner (refer to Figures 2A and 2B). First, the laminate of the adhesive sheet 1 and the supporting film 51 to be evaluated is cut into short pieces of 10 mm × 50 mm to make a test piece 52. The purpose of the configuration of the supporting film 51 is to suppress the deformation of the load-applying portion of the adhesive sheet 1 to which the load is applied during the test so as to more accurately measure the latent variable. For the supporting film 51, a resin film such as a polyethylene terephthalate (PET) film can be used. The supporting film 51 can be an optical film or a laminate including an optical film. The thickness of the supporting film 51 can be a thickness that does not deform due to the above-mentioned load, for example, 20~200µm. Next, as shown in FIG. 2A and FIG. 2B , the test piece 52 is attached to the surface of the stainless steel test plate 53 by the adhesive sheet 1 with a bonding surface of 10 mm long × 10 mm wide. In addition, FIG. 2B is a cross-section B-B of FIG. 2A . The test piece 52 is attached to the test plate 53 in a manner that does not mix air bubbles between the test plate 53 and the adhesive sheet 1. After attachment, it is placed in a high pressure autoclave at 50°C and 5 atmospheres (absolute pressure) for 15 minutes to homogenize the bonding between the test plate 53 and the adhesive sheet 1. Next, the test plate 53 and the test piece 52 are kept vertically in a 25°C gas environment with the test plate 53 at the top, and placed for at least 5 minutes. A weight of 500 g is fixed at the center of the lower end of the test piece 52 while the test plate 53 is fixed, and a load 54 of 500 gf is added vertically downward. After the load 54 is added, the latent variable (offset) of the adhesive sheet 1 to the test plate 53 is measured at a time point of 3600 seconds after the load 54 is added, as the amount of weight dropped. A laser displacement meter can be used to measure the amount of weight dropped.

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.

(Optical film) The optical film 2 has a surface 2a opposite to the adhesive sheet 1. The surface 2a is, for example, in contact with the surface 1a of the adhesive sheet 1. The surface 2a of the optical film 2 may also be subjected to a surface modification treatment. If the surface 2a subjected to the surface modification treatment is used, there is a tendency to increase the above-mentioned anchoring force F. The surface modification treatment may be the same as that previously described for the surface 1a.

The surface 2a is preferably subjected to a corona treatment as a surface modification treatment. When the surface 2a is subjected to a corona treatment, the conditions such as the discharge amount can be appropriately adjusted within the range previously described for the surface 1a.

As mentioned 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 also 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.

The polarizing film includes a polarizer. The polarizing film typically includes a polarizer and a protective film (transparent protective film). The protective film is, for example, arranged to be in contact with the main surface (the surface with the widest area) of the polarizer. The polarizer may also be arranged between two protective films. The protective film may also be arranged on at least one side of the polarizer.

The polarizer is not particularly limited, and examples thereof include those obtained by adsorbing dichroic substances such as iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified films of ethylene-vinyl acetate copolymers and then uniaxially stretching them; polyene-based oriented films such as dehydrated polyvinyl alcohol films and dehydrogenated polyvinyl chloride films, etc. The polarizer is typically composed of a polyvinyl alcohol film (polyvinyl alcohol films include partially saponified films of ethylene-vinyl acetate copolymers) and dichroic substances such as iodine.

The thickness of the polarizer is not particularly limited, for example, it is 80µm or less, and can also be 50µm or less, 30µm or less, 25µm or less, and can also be 20µm or less. The lower limit of the thickness of the polarizer is not particularly limited, for example, it is 1µm or more, and can also be 5µm or more, 10µm or more, and can also be 15µm or more. The dimensional change of the thin polarizer (for example, the thickness is 20µm or less) is suppressed, which can help improve the durability of the optical laminate, especially the durability under high temperature.

The protective film may be made of thermoplastic resins having excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, etc. Specific examples of the thermoplastic resins include cellulose resins such as cellulose triacetate, polyester resins, polyether resins, polyester resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (northene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The material of the protective film may also be a thermosetting resin or UV-curing resin such as (meth) acrylic acid, urethane, acrylic urethane, epoxy, silicone, etc. When 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 through an adhesive, and a protective film made of a thermosetting resin or a UV-curing resin may be bonded to the other main surface of the polarizer. The protective film may also contain one or more arbitrary additives. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, etc.

In addition, the film containing (meth) acrylic resin tends to have a weak bonding strength with the adhesive sheet. However, in this embodiment, by performing surface modification treatment on the surface 2a of the optical film 2, even when the surface of the protective film containing (meth) acrylic resin is equivalent to the surface 2a of the optical film 2, the above-mentioned anchoring force F can still be adjusted to a sufficiently high value.

The thickness of the protective film can be appropriately determined, but is generally around 10~200μm based on strength, workability, film properties, etc.

Polarizers and protective films are usually bonded together through water-based adhesives. 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 the above adhesives include UV-curable adhesives and electron beam-curable adhesives. Electron beam-curable adhesives for polarizing plates exhibit suitable adhesion to various protective films. Adhesives may also contain metal compound fillers.

In the polarizing film, a phase difference film may be formed on the polarizer to replace the protective film. Other protective films, phase difference films, etc. may also be further provided on the protective film.

Regarding the protective film, a hard coating layer may be provided on the surface opposite to the surface in contact with the polarizer, and treatments such as anti-reflection, anti-sticking, diffusion, and anti-glare may also be performed.

The polarizing film may also be a circularly polarizing film.

The retardation film may be a film obtained by stretching a polymer film or a film obtained by aligning and fixing a liquid crystal material. The retardation film may have birefringence in the in-plane and/or thickness direction, for example.

The phase difference film includes: an anti-reflection phase difference film (refer to Japanese Patent Publication No. 2012-133303 [0221], [0222], [0228]), a viewing angle compensation phase difference film (refer to Japanese Patent Publication No. 2012-133303 [0225], [0226]), a viewing angle compensation tilt-oriented phase difference film (refer to Japanese Patent Publication No. 2012-133303 [0227]), etc.

The specific structure of the phase difference film, such as phase difference value, configuration angle, three-dimensional birefringence, single layer or multilayer, etc. is not particularly limited, and a known phase difference film can be used.

The thickness of the phase difference film is preferably 20µm or less, more preferably 10µm or less, more preferably 1-9µm, and particularly preferably 3-8µm.

The phase difference film may also include, for example, a quarter wavelength plate and/or a half wavelength plate in which the liquid crystal material is oriented and fixed.

(Manufacturing method of optical laminate) The optical laminate 10 can be manufactured by, for example, the following method. First, as shown in FIG. 3A or FIG. 3B, a first laminate 15 including a substrate sheet 21, a coating layer 22 containing a photocurable composition, and a peeling liner 23 is manufactured in sequence. By irradiating the first laminate 15 with light 14, an adhesive sheet 1 can be formed from the coating layer 22 (FIG. 3C).

The irradiation of the first laminate 15 with the light 14 is typically performed from the substrate sheet 21 side (FIG. 3A). At this time, the light 14 will penetrate the substrate sheet 21 to reach the coating layer 22, causing the coating layer 22 to harden. However, the irradiation of the light 14 can be performed from the peeling liner 23 side, or from both the peeling liner 23 and the substrate sheet 21 side (FIG. 3B). Before the peeling liner 23 is peeled off, the adhesive sheet 1 formed by the coating layer 22 is sandwiched by the substrate sheet 21 and the peeling liner 23 to constitute a part of the second laminate 16.

An example of the substrate of the release substrate 23 (hereinafter referred to as "substrate substrate") is a resin film. Examples of resins that may be contained in the substrate substrate are polyesters such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyether sulphates, polycarbonates, polyamides, polyimides, polyolefins, (meth) acrylic resins, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyarylates, and polyphenylene sulfide. The resin is preferably a polyester such as polyethylene terephthalate.

The release liner 23 may have a light 14 transmittance, or may have a light 14 transmittance to the same degree as that of the base sheet 21 .

The thickness of the release liner 23 is, for example, 10-200 μm, or 25-150 μm.

The release liner 23 may have a layer other than the liner base material. The release liner 23 may also have a release layer. The release liner 23 may have, for example, a liner base material and a release layer formed on one surface of the liner base material. The release liner 23 may be used in a manner such that the release layer is on the coating layer 22 side.

The release layer is typically a hardened layer of a release agent composition containing a release agent. For the release agent, various release agents such as polysilicone release agents, fluorine release agents, long-chain alkyl release agents, fatty acid amide release agents, and silicon powder can be used. The release liner 23 may also have a hardened layer of a release agent composition containing a polysilicone release agent as a main component (hereinafter referred to as "polysilicone release layer"). The polysilicone release layer is particularly suitable for taking into account both adhesion and releasability to the adhesive sheet 1. In addition, in this specification, the main component means the component with the largest content rate.

The silicone-based mold release agent includes various curing silicone materials such as addition reaction type, condensation reaction type, ultraviolet curing type, electron beam curing type, solvent-free type, etc., preferably addition reaction curing silicone materials. Addition reaction curing silicone materials are particularly suitable for forming a mold release layer that takes into account both adhesion to the adhesive sheet 1 and peelability. The curing silicone material can also be a silicone modified resin in which reactive silicone is introduced into organic resins such as urethane, epoxy, and alkyd resins by graft polymerization.

Examples of addition reaction curing polysiloxane materials are polyorganosiloxanes having vinyl or alkenyl groups in the molecule. Addition reaction curing polysiloxane materials may not have hydrosilyl groups. Examples of alkenyl groups are: 3-butenyl, 4-pentenyl, 5-hexenyl, 6-heptenyl, 7-octenyl, 8-nonenyl, 9-decenyl, 10-undecenyl and 11-dodecenyl. Examples of polyorganosiloxanes are: polyalkyl alkyl siloxanes such as polydimethylsiloxane, polydiethylsiloxane and polymethylethylsiloxane, polyalkyl aryl siloxane, and copolymers of multiple Si atom-containing monomers such as poly(dimethylsiloxane-diethylsiloxane). The polyorganosiloxane is preferably polydimethylsiloxane.

A mold release agent composition containing a polysilicone-based mold release agent as a main component (hereinafter referred to as a "polysilicone mold release agent composition") generally contains a crosslinking agent. An example of a crosslinking agent is a polyorganosiloxane having a hydrosilyl group. The crosslinking agent may also have two or more hydrosilyl groups in one molecule.

The silicone release agent composition may also contain a hardening catalyst. An example of a hardening catalyst is a platinum-based catalyst. Examples of platinum-based catalysts are platinum chloride, platinum olefin complexes, and platinum chloride olefin complexes. The amount of the platinum-based catalyst used is, for example, 10 to 1000 ppm (weight basis, converted to platinum) relative to the total solid content of the composition.

The silicone release agent composition may also contain additives. Examples of additives are peeling control agents and adhesion promoters. Examples of peeling control agents are unreactive silicone resins, and more specifically, organic silicones such as octamethylcyclotetrasiloxane and MQ resins. The total amount of peeling control agents and adhesion promoters used is, for example, 1 to 30% by weight relative to the total solid content of the composition. Other examples of additives are fillers, antistatic agents, antioxidants, ultraviolet absorbers, plasticizers, and colorants. The total amount of other additives used is, for example, less than 10% by weight relative to the total solid content of the composition.

The silicone mold release agent composition may also contain an organic solvent. 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 also be included. The amount of organic solvent used is preferably 80 to 99.9% by weight of the silicone mold release agent composition.

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. The release agent composition can be applied by various coating methods such as roller coating, contact roller coating, gravure coating, reverse coating, roller brush, spray coating, dip roller coating, rod coating, doctor blade coating, air knife coating, curtain coating, lip coating, and mold coating. Heating and drying can be applied by, for example, hot air drying. The heating temperature and time vary depending on the heat resistance of the substrate, but are usually 80~150℃ and 10 seconds~10 minutes. Active energy rays such as ultraviolet rays can also be used as needed.

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, or less than 65 nm. 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, or 50 nm or more.

The release liner 23 can be in the form of a single sheet or a long strip.

An example of the base sheet 21 is a resin film. Examples of the resin contained in the base sheet 21 are the same as the examples of the resin that can be contained in the backing substrate.

The base sheet 21 preferably has excellent transmittance of the light 14 .

The thickness of the base sheet 21 is, for example, 10 to 200 μm, or 25 to 150 μm.

The substrate sheet 21 may also be provided with a release layer on the surface of the coating layer 22. The examples of the release layer that the substrate sheet 21 may have and the method of making the same are the same as the examples of the release layer that the release liner 23 may have and the method of making the same. Both the release liner 23 and the substrate sheet 21 may also be provided with a release layer. In this case, the two release layers may also be formed of a release agent composition containing the same release agent as a main component. In addition, the thickness of the two release layers may be different, for example, the release layer provided by the substrate sheet 21 may also be thicker.

For the base sheet 21, a sheet having a greater peeling force with the adhesive sheet 1 than the peeling liner 23 can usually be selected.

The base sheet 21 may be in a single sheet or in a long strip.

The first laminate 15 can be formed, for example, by forming a coating layer 22 on a base sheet 21 (or a release liner 23), and disposing a release liner 23 (or a base sheet 21) on the formed coating layer 22. Alternatively, the first laminate 15 can be formed by flowing a photocurable composition into a space formed by the base sheet 21 and the release liner 23 with their main surfaces facing each other with a predetermined interval.

The coating layer 22 may be formed by various coating methods such as roller coating, contact roller coating, gravure coating, reverse coating, roller brush, spray coating, dip roller coating, rod coating, scraper coating, air knife coating, curtain coating, lip coating, and mold coating.

The thickness of the coating layer 22 can be adjusted according to the desired thickness of the adhesive sheet 1, for example, 5-500µm, 5-250µm, 5-150µm, 5-100µm, 5-50µm, 5-30µm, 5-25µm, and even 5-20µm.

The light 14 irradiated to the first laminate 15 is, for example, visible light or ultraviolet light having a wavelength shorter than 450 nm. The light 14 may also include light having a wavelength in the same region as the absorption wavelength of the photopolymerization initiator contained in the photocurable composition. The light 14 may also be short-wavelength light having a cutoff wavelength of 300 nm or less through a filter or the like, and the cutoff short-wavelength light is suitable for suppressing the degradation of the substrate sheet 21 caused by the light 14. The light source of the light 14 is, for example, a light irradiation device having an ultraviolet irradiation lamp. Examples of ultraviolet irradiation lamps include ultraviolet LED, low-pressure mercury lamp, medium-pressure mercury lamp, high-pressure mercury lamp, ultra-high-pressure mercury lamp, metal halogen lamp, xenon lamp, microwave-excited mercury lamp, black light lamp, chemical lamp, sterilization lamp, low-pressure discharge mercury lamp, and excimer laser. Two or more ultraviolet irradiation lamps may also be combined.

The irradiation of the light 14 may be continuous or intermittent.

The illumination intensity of the light 14 is, for example, 1 to 20 mW/cm ² . The irradiation time of the light 14 is, for example, 5 minutes to 5 hours. The accumulated light quantity of the light 14 on the first laminate 15 is, for example, 100 to 5000 mJ/cm ² .

Next, the peeling liner 23 is peeled off from the second laminate 16 to expose the surface of the adhesive sheet 1. By arranging the optical film 2 on the exposed surface of the adhesive sheet 1, the optical laminate 10 can be manufactured. In addition, the exposed surface of the adhesive sheet 1 can be subjected to surface modification treatment before arranging the optical laminate 2.

(Characteristics of optical laminate) From the perspective of workability, the adhesion force _P0 of the optical laminate 10 obtained by the following test 1 is preferably 8.0 N/25 mm or less. Test 1: The adhesive sheet 1 is attached to the alkali-free glass, and the 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 (adhesion force _P0 ) is measured.

Test 1 is conducted using the following method. First, the optical laminate 10 is cut into short pieces of 150 mm in length and 25 mm in width to form a test piece. Then, the test piece is attached to the alkali-free glass through the adhesive sheet 1. The alkali-free glass is glass that does not substantially contain alkali components (alkali metal oxides). Specifically, the weight ratio of the alkali components in the glass is, for example, less than 1000 ppm, and further, less than 500 ppm. The alkali-free glass is, for example, in the form of a plate and has a thickness of more than 0.5 mm.

The test piece is attached to the alkali-free glass using, for example, a laminating machine in a manner that prevents air bubbles from being mixed between the alkali-free glass and the adhesive sheet 1. After attaching the test piece, 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 so that the adhesive sheet 1 is closely attached to the alkali-free glass. Then, the test piece is peeled off from the aforementioned alkali-free glass at a peeling speed of 300 mm/min and a peeling angle of 90° (measured length 80 mm). At this time, the force required to peel the test piece off the alkali-free glass is measured at intervals of 1 time/0.5 seconds. The average value of the measured values is designated as the bonding force P ₀ .

The adhesion force _P0 is preferably 7.0 N/25 mm or less, and may 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 may be 3.5 N/25 mm or less. The lower limit of the adhesion force _P0 is, for example, 0.5 N/25 mm or more, and may be 1.0 N/25 mm or more, and may be 1.5 N/25 mm or more. The adhesion force _P0 is preferably 0.5-7.0 N/25 mm.

The difference (FP ₀ ) between the anchoring force F and the holding force P ₀ is preferably 5.0 N/25 mm or more, and may 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 may be 13.0 N/25 mm or more. The upper limit of the difference (FP ₀ ) is, for example, 20 N/25 mm or less.

Furthermore, from the perspective of durability, the adhesive sheet 1 of the optical laminate 10 should be subjected to a heat treatment in a state where it is in contact with the alkali-free glass to improve its adhesion. For example, the adhesion force P1 of the optical laminate 10 obtained by the following test 2 should be 8.0N/25mm or more. Test 2: The adhesive sheet ₁ is attached to the alkali-free glass and heat-treated at 60°C for 100 hours. The adhesive sheet 1 is peeled off from the alkali-free glass at a peeling speed of 300mm/min and a peeling angle of 90°. The force required at this time (adhesion force _P1 ) is measured.

Test 2 was conducted in the same manner as Test 1 except that the bonding of the alkali-free glass and the adhesive sheet 1 was homogenized in an autoclave, and then heat-treated at 60°C for 100 hours under atmospheric pressure, and the temperature of the test sheet was lowered to room temperature (e.g., 23°C) before the test sheet was peeled off from the alkali-free glass.

The adhesion force _P1 is preferably 9.0 N/25 mm or more, and may 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 adhesion force _P1 is, for example, 20 N/25 mm or less.

FIG4 shows another example of an optical laminate of the present embodiment. The optical laminate 11 of FIG4 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 sequence. The optical laminate 11 may also have a structure in which a base sheet used in manufacturing the adhesive sheet 1A is laminated on the adhesive sheet 1A.

In the optical laminate 11, typically, the optical film 2A is a phase difference film, and the optical film 2B is a polarizing film. The adhesive sheet 1B functions as an adhesive between the optical films 2A and 2B. The adhesive sheet 1B may be made of a known adhesive.

The optical multilayer of the present embodiment can be distributed and stored in the form of a rolled body formed by rolling a strip-shaped optical multilayer or in the form of a single-sheet optical multilayer.

The optical multilayer body of this embodiment can typically be used in an image display device. The image display device can be formed by, for example, joining the optical multilayer body 10 or 11 and the image display panel. The joining is performed by, for example, an adhesive sheet 1. The image display device can 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 can also be an electroluminescent (EL) display, a plasma display (PD), a field emission display (FED: Field Emission Display), etc. The image display device can be used for home appliances, vehicles, public information displays (PID), etc.

Implementation Examples The present invention is further described in detail below through implementation examples. The present invention is not limited to the implementation examples shown below.

[Polarizing film] First, a polyvinyl alcohol film with a thickness of 80µm was dyed in an iodine solution with a concentration of 0.3% at a temperature of 30°C for 1 minute between rollers with different speed ratios and stretched to 3 times. Then, it was immersed in an aqueous solution containing boric acid at a concentration of 4% and potassium iodide at a concentration of 10% at a temperature of 60°C for 0.5 minutes, and stretched to a total stretching ratio of 6 times. Then, it was immersed in an aqueous solution containing potassium iodide at a concentration of 1.5% at a temperature of 30°C for 10 seconds, washed, and dried at 50°C for 4 minutes, thereby obtaining a polarizer with a thickness of 28µm. A transparent protective film with a thickness of 30µm made of a modified acrylic polymer having a lactone ring structure was bonded to one side of the polarizer using a polyvinyl alcohol adhesive. A transparent protective film with a thickness of 47µm formed on a cellulose triacetate film (manufactured by Konica Minolta, trade name "KC4UY") was bonded to the other side of the polarizer using a polyvinyl alcohol adhesive. The film was heated and dried in an oven set at 70°C for 5 minutes to produce a polarizing film. The surface of the polarizing film on the transparent protective film side made of a modified acrylic polymer was subjected to a corona treatment with a discharge of 63W/ ^m2 /min.

[Releasable liner A] 30 parts by weight of addition reaction curing type silicone (LTC761 containing hexene-containing polyorganosiloxane, 30% by weight toluene solution, manufactured by Dow Corning Toray Co., Ltd.), 0.9 parts by weight of a stripping control agent (BY24-850 containing unreacted silicone resin, manufactured by Dow Corning Toray Co., Ltd.), 2 parts by weight of a curing catalyst (SRX212 containing platinum catalyst, manufactured by Dow Corning Toray Co., Ltd.), and a toluene/hexane mixed solvent (volume ratio 1:1) as a diluent were mixed to obtain a silicone-based release agent composition. The concentration of the silicone solid component in the release agent composition was 1.0% by weight. Next, the release agent composition was applied to one side of the liner substrate (polyester film Lumirror XD500P, thickness 75µm) using a wire rod and heated at 130°C for 1 minute to produce a release liner A with a release layer (thickness 60nm) on one side.

[Release liner B] Release liner B with a release layer (thickness 120nm) on one side was prepared in the same manner as that of release liner A except that the thickness of the release agent composition to be applied to the liner substrate was changed.

[Monomer slurry A1] 95.2 parts by weight of n-butyl acrylate (BA) and 4.8 parts by weight of acrylic acid (AA), 0.05 parts by weight of 1-hydroxycyclohexyl-phenyl ketone (Omnirad184, manufactured by IGM Resins B.V.) as a photopolymerization initiator, and 0.05 parts by weight of 2,2-dimethoxy-1,2-diphenylethan-1-one (Omnirad651, manufactured by IGM Resins B.V.) were placed in a four-necked flask and irradiated with ultraviolet light in a nitrogen environment to obtain partially photopolymerized monomer slurry A1. Ultraviolet light irradiation was performed until the viscosity of the liquid in the flask (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30°C) reached about 20 Pa·s.

[Monomer slurry A2] Except that the monomers to be used are changed as shown in Table 1, monomer slurry A2 is prepared in the same manner as monomer slurry A1.

[Table 1]

The abbreviations in Table 1 are as follows. BA: n-butyl acrylate AA: acrylic acid HBA: 4-hydroxybutyl acrylate

[Photocurable compositions C1 to C6] Then, the monomer slurry, the crosslinking agent and the heavy-duty enhancer are mixed in a manner as shown in Table 2 below to obtain photocurable compositions C1 to C6.

[Table 2]

The abbreviations in Table 2 are as follows. NDDA: 1,9-nonanediol diacrylate D376N: Trimeric isocyanate modified pentamethylene diisocyanate (Mitsui Chemicals, STABiO D-376N) SAT10: Polyether compound with alkoxysilyl group (Kaneka, Silyl SAT10) 9591F: Oligomeric silane coupling agent containing anhydride group (Shin-Etsu Chemical, X-24-9591F) 1056: Oligomeric silane coupling agent containing epoxy group (Shin-Etsu Chemical, X-41-1056)

(Example 1) A photocurable composition C1 is applied to the surface of the release layer of the release liner A by a sprinkler to form a coating layer (thickness 20 μm). Then, the release liner B is arranged on the formed coating layer to obtain the first laminate. The release liner B is arranged so that the release layer is in contact with the coating layer. Next, the coating layer was photocured by irradiating the release liner A side of the first laminate with ultraviolet light (black light source) at an illumination of 2.5 mW/cm ² and an irradiation time of 640 seconds, thereby forming a second laminate consisting of the release liner A, the adhesive sheet (thickness 20 µm) and the release liner B.

Next, the release liner B was peeled off from the second laminate, and the polarizing film was arranged on the exposed surface of the adhesive sheet, thereby obtaining the optical laminate of Example 1. In addition, the polarizing film was arranged so that the surface of the transparent protective film side composed of a modified acrylic polymer was in contact with the adhesive sheet.

(Example 2) The optical laminate of Example 2 was obtained in the same manner as in Example 1 except that the release liner B was peeled off from the second laminate, the exposed surface of the adhesive sheet was subjected to a corona treatment at a discharge amount of 61 W/m ² min, and a polarizing film was disposed on the exposed surface.

(Examples 3 to 6) Except that the photocurable composition to be used is changed as shown in Table 3, the optical laminates of Examples 3 to 6 are obtained in the same manner as in Example 2.

(Example 7) Except that the photocurable composition to be used is changed as shown in Table 3, the optical laminate of Example 7 is obtained by the same method as Example 1.

(Comparative Example 1) Except that the exposed surface of the adhesive sheet is not subjected to the corona treatment, the optical laminate of Comparative Example 1 is obtained in the same manner as in Example 6.

(Comparative Example 2) Except that the exposed surface of the adhesive sheet is not subjected to the corona treatment, the optical multilayer body of Comparative Example 2 is obtained in the same manner as in Example 4.

(Comparative Example 3) Except that the exposed surface of the adhesive sheet is not subjected to the corona treatment, the optical multilayer body of Comparative Example 3 is obtained in the same manner as in Example 5.

[Anchor force] For the optical multilayers of the embodiment and the comparative example, the anchor force F of the adhesive sheet and the polarizing film was measured using the above method. The double-sided adhesive tape used was the product name "No.531" manufactured by Nitto Denko Corporation. The stainless steel test material used was a SUS304 plate (width 40mm×length 120mm). The evaluation sheet used was an ITO film (125 TETOLIGHT OES, manufactured by Oike Industries). The tensile testing machine used was Autograph SHIMAZU AG-I 10KN (manufactured by Shimadzu Corporation).

[Adhesion Force] Adhesion forces _P0 and _P1 were measured for the optical laminates of the embodiment and the comparative example by performing the above-mentioned tests 1 and 2. Tests 1 and 2 used alkali-free glass (manufactured by Corning Incorporated, trade name "EG-XG") with a thickness of 0.7 mm. The operation of peeling the test piece from the alkali-free glass was performed using a tensile testing machine (manufactured by Shimadzu Corporation, Autograph SHIMAZU AG-1 10KN).

[Durability] The durability (85°C durability) of the optical laminates of the embodiments and comparative examples was evaluated using the following method. First, the optical laminate was cut into short pieces of 300 mm long and 220 mm wide to make test pieces. Then, the test pieces were attached to the surface of 0.7 mm thick alkali-free glass (Corning Incorporated, trade name "EG-XG") through an adhesive sheet. The test piece was attached to the alkali-free glass using a bonding machine. After the test piece was attached, it was placed in an autoclave at 50°C and 0.5MPa for 15 minutes to homogenize the bond between the alkali-free glass and the adhesive sheet so that the adhesive sheet was closely attached to the alkali-free glass. Then, the test piece was heat treated at atmospheric pressure and 85°C for 500 hours. Observe the appearance of the adhesive sheet between the polarizing film and the alkali-free glass with the naked eye, and evaluate the durability of the adhesive sheet according to the following criteria. (Evaluation criteria) A: There is no change in appearance such as bubbling or peeling. B: There is a slight peeling of less than 0.3mm or bubbling at the end, but there is no problem in practical use. C: There is a peeling of less than 1mm or bubbling at the end. D: There is a peeling of more than 1mm at the end.

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

[table 3]

As shown in Table 3, the anchoring force F between the adhesive sheet and the optical film (polarizing film) of the optical laminate of the embodiment is above 10.0N/25mm, so that the durability at 85°C is better than that of the comparative example. Moreover, even when evaluating the durability at 95°C, it is almost impossible to confirm that the polarizing film and the adhesive sheet of the optical laminate of the embodiment have peeling. As mentioned above, we speculate that the optical laminate of the embodiment has suppressed the peeling between the polarizing film and the adhesive sheet, so if the optical laminate is used, the image display function of the image display device can be suppressed.

Furthermore, as can be seen from Table 3, Examples 4 and 5 also achieved good durability at 95°C. Such multilayer bodies are particularly suitable for applications requiring durability in high temperature environments, such as automotive applications.

Industrial Applicability The optical multilayer body of the present invention can be used in, for example, image display devices.

1,1A,1B: Adhesive sheet 1a,1b: Surface of adhesive sheet 2,2A,2B: Optical film 2a: Surface of optical film 10,11: Optical laminate 14: Light 15: 1st laminate 16: 2nd laminate 21: Base sheet 22: Coating layer 23: Peeling liner 51: Support film 52: Test piece 53: Test plate 54: Load B-B: Cross section

FIG. 1 is a cross-sectional view schematically showing an example of the optical multilayer body of the present invention. FIG. 2A is a schematic view for illustrating a method for measuring a latent variable for an adhesive sheet. FIG. 2B is a schematic view for illustrating a method for measuring a latent variable for an adhesive sheet. FIG. 3A is a schematic view for illustrating an example of a method for manufacturing the optical multilayer body of the present invention. FIG. 3B is a schematic view for illustrating an example of a method for manufacturing the adhesive sheet of the present invention. FIG. 3C is a schematic view for illustrating an example of a method for manufacturing the optical multilayer body of the present invention. FIG. 4 is a cross-sectional view schematically showing an example of the optical multilayer body of the present invention.

1: Adhesive sheet

1a, 1b: Surface of adhesive sheet

2: Optical film

2a: Surface of optical film

10: Optical laminates

Claims (16)

An optical laminate, comprising: an adhesive sheet formed of a photocurable composition; and an optical film comprising at least one selected from the group consisting of a polarizing film and a phase difference film; and the anchoring force between the adhesive sheet and the optical film is greater than 10.0N/25mm. The optical multilayer of claim 1, wherein the anchoring force is greater than 16.0 N/25 mm. The optical laminate of claim 1 has an adhesion force _P0 of less than 8.0 N/25 mm obtained by the following test: The adhesive sheet is attached to an alkali-free glass, and the adhesive sheet 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 (adhesion force _P0 ) is measured. The optical multilayer of claim 3, wherein the adhesion force _P0 is 0.5~7.0N/25mm. The optical multilayer of claim 3, wherein the difference between the anchoring force and the holding force _P0 is greater than 5.0 N/25 mm. The optical laminate of claim 1 has an adhesion force _P1 of 10.0 N/25 mm or more obtained by the following test: the adhesive sheet is attached to an alkali-free glass and heat-treated at 60° C. for 100 hours; the adhesive sheet is peeled off from the alkali-free glass at a peeling speed of 300 mm/min and a peeling angle of 90°; and the force required at this time (adhesion force _P1 ) is measured. The optical laminate of claim 1, wherein the content of the solvent in the photocurable composition is 5 wt % or less. The optical laminate of claim 1, wherein the adhesive sheet has a surface opposite to the optical film and subjected to surface modification treatment. The optical laminate of claim 1, wherein the adhesive sheet has a surface opposite to the optical film; and after the surface is treated with trifluoroethanol, the element ratio R of fluorine in the surface is greater than 0.1 atomic %. The optical laminate of claim 1, wherein the optical film has a surface opposite to the adhesive sheet and subjected to surface modification treatment. The optical laminate of claim 1, wherein the photocurable composition comprises a monomer group containing a (meth)acrylic monomer and/or a partial polymer of the monomer group. The optical layered structure of claim 11, wherein the monomer group comprises carboxyl-containing monomers. The optical layered product of claim 11, wherein the monomer group comprises ether-containing monomers. The optical laminate of claim 1, wherein the photocurable composition comprises a reworking enhancer. An optical layered structure as claimed in claim 14, wherein the aforementioned heavy-duty enhancing agent is a silane coupling agent. The optical laminate of claim 1, wherein the photocurable composition comprises an isocyanate crosslinking agent.

Images