JP2022001429A - Laminate, image display unit, and production method thereof - Google Patents

Abstract

To provide a laminate comprising a first optical member, a first adhesive layer, a second optical member, a second adhesive layer, and a third optical member disposed in this sequence, capable of maintaining the adhesiveness between the adhesive layer and the optical member even when the third optical member is bent inward, and suppressing generation of bubbles between the adhesive layer and the optical member or in the adhesive layer.SOLUTION: A laminate includes a first optical member, a first adhesive layer, a second optical member, a second adhesive layer, and a third optical member disposed in this sequence. Both of the first adhesive layer and the second adhesive layer have a tackiness value of 0.8 gf or more at 25°C, satisfying an expression (1).SELECTED DRAWING: None

Description

The present invention relates to a laminated body, and further relates to an image display device including the laminated body and a method for manufacturing the laminated body.

Patent Document 1 describes a window film, a second pressure-sensitive adhesive film, a touch function unit, a first pressure-sensitive adhesive film, and an optical member provided in this order, depending on the temperature of the first pressure-sensitive adhesive film and the second pressure-sensitive adhesive film. It has been proposed that the distribution of the stored elastic coefficient be within a specific range.

Patent Document 2 describes a pressure-sensitive adhesive composition for a bendable display, and specifies the ratio of the final stress after deformation to the initial stress at the start of deformation with respect to the storage elastic modulus after curing of the pressure-sensitive adhesive composition. It is proposed to be within the range of.

Korean Published Patent No. 10-2016-0053788 Gazette Korean Publication No. 10-2019-0069334 Gazette

An optical laminate used in an image display device is generally manufactured by laminating a plurality of optical members with an adhesive layer. In order for the pressure-sensitive adhesive layer to exhibit its original performance in the next step, a step (aging) of aging the pressure-sensitive adhesive layer after coating may be required. In recent years, the lead time after the optical laminate is manufactured until it is used in the next process has become shorter. Therefore, sufficient time cannot be allocated for aging, and bubbles may be generated between the pressure-sensitive adhesive layer and the optical member or in the pressure-sensitive adhesive layer during bending.

An object of the present invention is a laminate including a first optical member, a first pressure-sensitive adhesive layer, a second optical member, a second pressure-sensitive adhesive layer, and a third optical member in this order, and is a third optical device. Adhesiveness between the adhesive layer and the optical member is maintained, and between the adhesive layer and the optical member and adhesion, even if sufficient time is not available for aging when the member is bent inward. It is an object of the present invention to provide a laminated body in which the generation of bubbles is suppressed in the agent layer.

The present invention provides the following laminated body, an image display device, and a method for manufacturing the laminated body.
[1] A laminate including a first optical member, a first pressure-sensitive adhesive layer, a second optical member, a second pressure-sensitive adhesive layer, and a third optical member in this order.
The tack value of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer at a temperature of 25 ° C. is 0.8 gf or more.
A laminated body satisfying the formula (1).
Tack value at a temperature of 25 ° C. of the second pressure-sensitive adhesive layer> Tack value at a temperature of 25 ° C. of the first pressure-sensitive adhesive layer (1)
[2] The laminate according to [1], wherein both the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer have a tack value of 10.0 gf or less at a temperature of 25 ° C.
[3] The laminate according to any one of [1] and [2], wherein the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer both have a shear modulus of 0.5 MPa or less at a temperature of 25 ° C.
[4] The laminate according to any one of [1] to [3], wherein the first optical member is a front plate.
[5] The laminate according to any one of [1] to [4], wherein the second optical member is a polarizing plate.
[6] The laminate according to any one of [1] to [5], wherein the third optical member is a touch sensor panel.
[7] An image display device including the laminate according to any one of [1] to [6].
[8] The method for manufacturing a laminate according to [1].
A method for producing a laminated body, which comprises a step of bonding optical members using an adhesive layer having a tack value of 0.8 gf or more at a temperature of 25 ° C.

According to the present invention, it is a laminate including a first optical member, a first pressure-sensitive adhesive layer, a second optical member, a second pressure-sensitive adhesive layer, and a third optical member in this order, and is a third optical. Adhesion between the adhesive layer and the optical member is maintained, and between the adhesive layer and the optical member and adhesion, even if sufficient time is not available for aging when the member is bent inward. It is an object of the present invention to provide a laminated body in which the generation of bubbles is suppressed in the agent layer.

It is a schematic cross-sectional view schematically showing an example of the laminated body of this invention. It is the schematic sectional drawing which shows typically the manufacturing method of the laminated body of this invention. It is a schematic diagram explaining the method of measuring the tack value at a temperature of 25 degreeC. It is a schematic diagram explaining the evaluation method of static bending durability.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In all the drawings below, the scales are appropriately adjusted and shown in order to make each component easier to understand, and the scale of each component shown in the drawings does not necessarily match the scale of the actual component.

<Laminated body>
FIG. 1 shows a schematic cross-sectional view of the laminated body. The laminate 100 includes a first optical member 110, a first pressure-sensitive adhesive layer 120, a second optical member 130, a second pressure-sensitive adhesive layer 140, and a third optical member 150 in this order. It is preferable that the first optical member 110 side of the laminated body 100 is the visual recognition side. The visual recognition side means the side to be visually recognized by the image display device when the laminated body 100 is used in the image display device. In the present specification, the first optical member, the second optical member, and the third optical member may be collectively referred to as an optical member. Further, in the present specification, the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer may be collectively referred to as a pressure-sensitive adhesive layer.

The laminated body 100 can be bent with the third optical member 150 side inside. Being able to bend means that the laminate can be bent without creating bubbles between the pressure-sensitive adhesive layer and the optical member and in the pressure-sensitive adhesive layer. Bending includes a form of bending in which a curved surface is formed on the bent portion. In the form of bending, the bending radius of the bent inner surface is not particularly limited, but for example, the bending radius of the bent portion may be 15 mm or less, 10 mm or less, or 5 mm or less. The bending radius is, for example, in the range of 0.5 mm to 5.0 mm. Further, "bending" includes a form of refraction in which the angle of the bent inner surface is greater than 0 degrees and less than 180 degrees unless otherwise specified, and the bending radius of the inner surface is close to zero, or the refraction angle of the inner surface is 0. Includes forms that are degrees. When the bent portion is a curved line, the angle formed by the straight line sandwiching the bent portion is defined as the angle of the inner surface.

[Static bending durability]
When a static bending durability test was performed on the laminated body 100 to maintain a bending state in which the bending radius was 2.5 mm with the third optical member 150 side inside, the adhesive layer and the adhesive layer were formed at the bending portion. Bubbles tend to be less likely to occur between the optical member and the pressure-sensitive adhesive layer. When the static bending durability test is performed on the laminated body 100, the time until bubbles are first generated between the pressure-sensitive adhesive layer and the optical member and in the pressure-sensitive adhesive layer at the bent portion is preferably more than 48 hours. , More preferably over 72 hours. The static bending durability test can be performed by the method described in Examples described later.

The laminate 100 may have, for example, a square shape in a plan view, preferably a square shape having a long side and a short side, and more preferably a rectangle. Each layer constituting the laminated body 100 may have a corner portion R-processed, an end portion notched, or a perforated portion.

The laminated body 100 can be used, for example, in an image display device or the like. The image display device is not particularly limited, and examples thereof include an organic electroluminescence (organic EL) display device, an inorganic electroluminescence (inorganic EL) display device, a liquid crystal display device, and an electroluminescence display device. Since the laminated body 100 can be bent, it is suitable for a flexible display.

[Tack value of the adhesive layer at a temperature of 25 ° C]
The tack value of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer at a temperature of 25 ° C. is 0.8 gf or more. The tack value is considered to be related to the initial adhesion force after the pressure-sensitive adhesive layer and the optical member are bonded together. Therefore, if the tack value is included in the above range, it is presumed that a laminated body having excellent static bending durability can be obtained even when sufficient time cannot be allocated for aging. When either or both of the tack values of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer at a temperature of 25 ° C. is less than 0.8 gf, interfacial peeling tends to occur easily after bending due to insufficient adhesive force. .. The tack value of the pressure-sensitive adhesive layer at a temperature of 25 ° C. is measured according to the method described in Examples described later.

The tack values of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer at a temperature of 25 ° C. are preferably 1.0 gf or more, more preferably 1.1 gf or more, still more preferably 1 from the viewpoint of excellent static bending durability. It is .2 gf or more, particularly preferably 1.3 gf or more, more particularly preferably 1.4 gf or more, still more preferably 1.5 gf or more, and particularly preferably 2.0 gf or more. The tack value of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer at a temperature of 25 ° C. may be, for example, 10.0 gf or less, preferably 9.0 gf or less, more preferably 8.0 gf or less, still more preferably 7. It is 0.0 gf or less, particularly preferably 6.0 gf or less, more particularly preferably 5.0 gf or less, and even more preferably 3.8 gf or less. When the tack value of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer at a temperature of 25 ° C. exceeds 10.0 gf, the cohesive force inside the pressure-sensitive adhesive layer tends to decrease.

The laminated body 100 satisfies the following formula (1).
Tack value at a temperature of the second pressure-sensitive adhesive layer of 25 ° C.> Tack value at a temperature of the first pressure-sensitive adhesive layer of 25 ° C. (1)
When bending the laminate with the third optical member side inside, it is better that the tack value of the second pressure-sensitive adhesive layer at a temperature of 25 ° C. is larger than the tack value of the first pressure-sensitive adhesive layer at a temperature of 25 ° C. It was found that the static bending durability tends to be easily obtained. When bending the laminate with the third optical member side inside, the second pressure-sensitive adhesive layer is arranged closer to the third optical member than the first pressure-sensitive adhesive layer, so that the bending radius is smaller. The applied stress tends to increase. Therefore, it is presumed that by arranging the pressure-sensitive adhesive layer having a larger tack value as the second pressure-sensitive adhesive layer, it becomes easier to maintain the close contact state.

The tack value of the pressure-sensitive adhesive layer at a temperature of 25 ° C. tends to be higher as the pressure-sensitive adhesive layer is more flexible. The tack value of the pressure-sensitive adhesive layer at a temperature of 25 ° C. can be adjusted by selecting the type and amount of the monomer constituting the base polymer and the additive (for example, acrylic monomer) to be added to the pressure-sensitive adhesive. The tack value of the pressure-sensitive adhesive layer at a temperature of 25 ° C. may be adjusted by adding a pressure-sensitive adhesive (tack fire).

[Optical member]
The optical member can be a component used in a normal image display device. When the laminated body 100 is used in an image display device, the first optical member 110 can be attached to the image display device so that the first optical member 110 is on the visual recognition side, and preferably the first optical member 110 is on the visual recognition side of the image display device. It is attached to the image display device so as to be a layer constituting the outermost surface of the image.

Examples of the optical member include a front plate, a polarizing plate, a touch sensor panel, an image display element, and the like. The first optical member 110 can be a front plate. The second optical member 130 can be a polarizing plate. The third optical member 150 can be a touch sensor panel or an image display element, preferably a touch sensor panel.

[Front plate]
The material and thickness of the front plate are not limited as long as it is a plate-like body capable of transmitting light, and the front plate may have a single-layer structure or a multi-layer structure, and may be a glass plate-like body (for example, glass). Examples thereof include a plate (plate, glass film, etc.), a resin plate (for example, a resin plate, a resin sheet, a resin film, etc.), and a laminate of a resin plate and a glass plate. The front plate can be a layer constituting the outermost surface on the visual side of the image display device.

As the glass plate, tempered glass for a display is preferably used. The thickness of the glass plate is, for example, 10 μm or more and 1000 μm or less, preferably 20 μm or more and 500 μm or less. By using a glass plate, it is possible to construct an optical member having excellent mechanical strength and surface hardness.

The resin film is not limited as long as it is a resin film capable of transmitting light. For example, triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, polyester, polystyrene, polyamide, polyetherimide, poly (meth) acrylic, polyimide, polyether. Polysulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polymethyl (meth) acrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene na Examples thereof include a film formed of a polymer such as phthalate, polycarbonate, and polyamideimide. These polymers can be used alone or in combination of two or more. When the laminate is used for a flexible display, a resin film made of a polymer such as polyimide, polyamide, or polyamideimide, which has excellent flexibility and can be configured to have high strength and high transparency. Is preferably used. In addition, in this specification, "(meth) acrylic" means that either acrylic or methacrylic may be used. "(Meta)" such as (meth) acrylate has the same meaning.

When the front plate is a resin film, the resin film may be a film having a hard coat layer provided on at least one surface of the base film to further improve the hardness. The hard coat layer may be formed on one surface of the base film or may be formed on both surfaces. When the image display device described later is a touch panel type image display device, the surface of the front plate serves as a touch surface, so that a resin film having a hard coat layer is preferably used. By providing the hard coat layer, it is possible to obtain a resin film having improved hardness and scratch resistance. The hard coat layer is, for example, a cured layer of an ultraviolet curable resin. Examples of the ultraviolet curable resin include (meth) acrylic resin, silicone resin, polyester resin, urethane resin, amide resin, epoxy resin and the like. The hardcourt layer may contain additives to improve hardness. The additive is not limited, and examples thereof include inorganic fine particles, organic fine particles, or a mixture thereof. The thickness of the resin film is, for example, 10 μm or more and 500 μm or less, preferably 20 μm or more and 100 μm or less.

The front plate not only has a function of protecting the front surface of the image display device, but may also have a function as a touch sensor, a blue light cut function, a viewing angle adjusting function, and the like.

[Polarizer]
The polarizing plate 130 may be a linear polarizing plate or a circular polarizing plate. The linear polarizing plate can be one in which a protective layer is laminated on one surface of the polarizing element. The linearly polarizing plate has a property of transmitting linearly polarized light having a vibration plane orthogonal to the absorption axis when unpolarized light is incident. The linear polarizing plate may contain a polyvinyl alcohol (hereinafter, may be abbreviated as “PVA”) resin film as a polarizing element, and a composition containing a dichroic dye and a polymerizable compound is oriented. , A cured film obtained by polymerizing a polymerizable liquid crystal compound may be used. A polarizing element obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound is preferable because there is no limitation in the bending direction as compared with a polarizing element of a PVA-based resin film including a stretching step.

The linear polarizing plate may include only a polarizing element and a protective layer, or may include one or more of a substrate, a thermoplastic resin film, an overcoat layer, and an alignment film in addition to the polarizing element and the protective layer. Further may be included. The thickness of the linear polarizing plate is, for example, 2 μm or more and 100 μm or less, preferably 5 μm or more and 60 μm or less.

[Polarizer]
Examples of the substituent include a hydrophilic polymer film such as a polyvinyl alcohol (hereinafter, may be abbreviated as “PVA”) film, a partially formalized PVA film, and an ethylene / vinyl acetate copolymerization system partially saponified film. Examples thereof include those subjected to a dyeing treatment with a dichroic substance such as iodine or a dichroic dye, and a stretching treatment. Since it is excellent in optical properties, it is preferable to use a polarizing element obtained by dyeing a PVA-based resin film with iodine and uniaxially stretching it.

The polyvinyl alcohol-based resin can be produced by saponifying the polyvinyl acetate-based resin. The polyvinyl acetate-based resin may be a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

The saponification degree of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can also be used. The average degree of polymerization of the polyvinyl alcohol-based resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000. The average degree of polymerization of the polyvinyl alcohol-based resin can be determined in accordance with JIS K 6726 (1994). If the average degree of polymerization is less than 1000, it is difficult to obtain preferable polarization performance, and if it exceeds 10,000, the film processability may be inferior.

As another method for producing a polarizing element containing a PVA-based resin film, a base film is first prepared, a resin solution such as polyvinyl alcohol-based resin is applied onto the base film, and drying is performed to remove the solvent. Examples thereof include a step of forming a resin layer on a base film. A primer layer can be formed in advance on the surface of the base film on which the resin layer is formed. As the base film, a resin film such as PET or a film using a thermoplastic resin that can be used for the protective layer described later can be used. Examples of the material of the primer layer include a resin obtained by cross-linking a hydrophilic resin used for a polarizing element.

Then, if necessary, the amount of solvent such as water content of the resin layer is adjusted, then the base film and the resin layer are uniaxially stretched, and then the resin layer is dyed with a dichroic dye such as iodine to obtain two colors. The sex dye is adsorbed and oriented on the resin layer. Subsequently, if necessary, the resin layer in which the dichroic dye is adsorbed and oriented is treated with a boric acid aqueous solution, and a washing step of washing off the boric acid aqueous solution is performed. As a result, a resin layer in which the dichroic dye is adsorbed and oriented, that is, a polarizing element is manufactured. A known method can be adopted for each step.

The uniaxial stretching of the base film and the resin layer may be performed before dyeing, during dyeing, or during boric acid treatment after dyeing, and each of these multiple stages is uniaxial. Stretching may be performed. The base film and the resin layer may be uniaxially stretched in the MD direction (film transport direction), in this case, may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a thermal roll. You may. Further, the base film and the resin layer may be uniaxially stretched in the TD direction (direction perpendicular to the film transport direction), and in this case, the so-called tenter method can be used. Further, the stretching of the base film and the resin layer may be a dry stretching in which the resin layer is stretched in the atmosphere, or a wet stretching in which the resin layer is swollen with a solvent. In order to exhibit the performance of the polarizing element, the draw ratio is 4 times or more, preferably 5 times or more, and particularly preferably 5.5 times or more. There is no particular upper limit to the draw ratio, but it is preferably 8 times or less from the viewpoint of suppressing breakage and the like.

The thickness of the polarizing element containing the PVA-based resin film is, for example, 2 μm or more and 40 μm or less. The thickness of the polarizing element may be 5 μm or more, 20 μm or less, 15 μm or less, and further 10 μm or less.

As a method for producing a polarizing element, which is a cured film obtained by orienting a composition containing a dichroic dye and a polymerizable liquid crystal and polymerizing the polymerizable liquid crystal compound, a polymerizable liquid crystal is formed on a base film via an alignment film. A method of forming a polarizing element by applying a polarizing element forming composition containing a compound and a dichroic dye, or a polymerizable liquid crystal compound on a protective layer to be described later formed on a base film via an alignment film. A method of applying a polarizing element-forming composition containing a dichroic dye and polymerizing and curing a polymerizable liquid crystal compound while maintaining the liquid crystal state to form a polarizing element can be mentioned. The polarizing element thus obtained is in a state of being laminated on the protective layer of the base film, and may be used as a linear polarizing plate with a base film. As the base film, a thermoplastic resin film, for example, a polyethylene terephthalate film or the like can be used.

As the dichroic dye, a dye having a property that the absorbance in the major axis direction and the absorbance in the minor axis direction of the molecule are different can be used. For example, a dye having an absorption maximum wavelength (λmax) in the range of 300 to 700 nm can be used. preferable. Examples of such a dichroic dye include an acridine dye, an oxazine dye, a cyanine dye, a naphthalene dye, an azo dye, an anthraquinone dye and the like, and among them, the azo dye is preferable. Examples of the azo dye include a monoazo dye, a bisazo dye, a trisazo dye, a tetrakisazo dye, a stilbene azo dye and the like, and a bisazo dye and a trisazo dye are more preferable.

The composition for forming a polarizing element may contain a solvent, a polymerization initiator such as a photopolymerization initiator, a photosensitizer, a polymerization inhibitor and the like. As the polymerizable liquid crystal compound, the dichroic dye, the solvent, the polymerization initiator, the photosensitizer, the polymerization inhibitor and the like contained in the composition for forming a polarizing element, known ones can be used, for example, special features. The ones exemplified in Japanese Patent Publication No. 2017-102479 and Japanese Patent Application Laid-Open No. 2017-83843 can be used. As a method for forming a polarizing element using a composition for forming a polarizing element, the method exemplified in the above-mentioned publication can also be adopted.

The thickness of the polarizing element obtained by applying and curing the composition containing the dichroic dye and the polymerizable compound is usually 10 μm or less, preferably 0.5 μm or more and 8 μm or less, and more preferably 1 μm or more and 5 μm or less. Is.

An overcoat layer (hereinafter, also referred to as an OC layer) may be provided on the surface of the linear polarizing plate on the polarizing element side. Examples of the material constituting the OC layer include a photocurable resin and a water-soluble polymer. Examples of the photocurable resin include (meth) acrylic resin, urethane resin, (meth) acrylic urethane resin, epoxy resin, silicone resin and the like. Examples of the water-soluble polymer include poly (meth) acrylamide-based polymers; polyvinyl alcohol and ethylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, (meth) acrylic acid or its anhydride-vinyl alcohol co-weight. Examples thereof include vinyl alcohol-based polymers such as coalesced; carboxyvinyl-based polymers; polyvinylpyrrolidone; starches; sodium alginate; polyethylene oxide-based polymers. The thickness of the OC layer is preferably 20 μm or less, more preferably 15 μm or less, further preferably 10 μm or less, 5 μm or less, and 0.05 μm or more. It may be 0.5 μm or more.

The polarizing element produced by the above method may be used as a linear polarizing plate by peeling off the base film or using the base film together with the base film. According to the above method, since the base film can be peeled off, the polarizing element can be further thinned.

[Protective layer]
The protective layer has a function of protecting the surface of the polarizing element. In the laminated body 100, the linear polarizing plate can usually be arranged so that the protective layer is closer to the first optical member 110 than the polarizing element.

As the protective layer, for example, a thermoplastic resin film having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropic property, stretchability and the like can be used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyether sulfone resins; polysulfone resins; polycarbonate resins; polyamides such as nylon and aromatic polyamides. Resin; Polyimide resin; Polyethylene resin such as polyethylene, polypropylene, ethylene / propylene copolymer; Cyclic polyolefin resin having cyclo-based and norbornene structure (also referred to as norbornene-based resin); (meth) acrylic resin; polyallylate resin; polystyrene resin Polyvinyl alcohol resins, as well as mixtures thereof, can be mentioned. When the protective layer is laminated on both sides of the polarizing element, the two protective layers may be of the same type or different types. The thickness of the thermoplastic resin film may be, for example, 3 μm or more and 50 μm or less, preferably 5 μm or more and 30 μm or less.

The protective layer may be, for example, an organic layer or an inorganic layer. The organic or inorganic layer can be a layer formed by the coating. The organic layer can be formed by using a composition for forming a protective layer, for example, a (meth) acrylic resin composition, an epoxy resin composition, a polyimide resin composition, or the like. The composition for forming a protective layer may be an active energy ray-curable type or a thermosetting type. The inorganic layer can be formed from, for example, silicon oxide. When the protective layer is an organic layer, the protective layer may be what is called a hardcourt layer.

When the protective layer is an organic layer, the protective layer can be produced, for example, by applying an active energy ray-curable protective layer forming composition onto a base film and irradiating it with active energy to cure it. As for the base film, the above description of the base film is applied. The substrate film is usually stripped and removed. Examples of the method for applying the protective layer forming composition include a spin coating method and the like. When the protective layer is an inorganic layer, the protective layer can be formed by, for example, a sputtering method, a vapor deposition method, or the like. When the protective layer is an organic layer or an inorganic layer, the thickness of the protective layer may be, for example, 0.1 μm or more and 10 μm or less, preferably 0.5 μm or more and 5 μm or less.

[Phase difference plate]
The polarizing plate can exhibit a function as a circular polarizing plate by providing a linear polarizing plate and a retardation plate. A circularly polarizing plate in which a linearly polarizing plate and a retardation plate are arranged so that the absorption axis of the linearly polarizing plate and the slow axis of the retardation plate are at a predetermined angle can exhibit an antireflection function.
The retardation plate can include one layer or two or more retardation layers. When the retardation plate includes two retardation layers, it may be referred to as a first retardation layer and a second retardation layer in order from the polarizing element side. The retardation layer may be one layer or two or more layers. The retardation layer may have an overcoat layer that protects the surface thereof, a base film that supports the retardation layer, and the like. Examples of the phase difference layer include a phase difference layer (λ / 4 layer) that gives a phase difference of λ / 4, a phase difference layer (λ / 2 layer) that gives a phase difference of λ / 2, a positive C layer, and the like. .. The retardation plate preferably comprises a λ / 4 layer, more preferably a λ / 4 layer and at least one of a λ / 2 layer or a positive C layer. When the retardation plate contains a λ / 2 layer, the λ / 2 layer and the λ / 4 layer are laminated in order from the linear polarizing plate side. When the retardation plate contains a positive C layer, the λ / 4 layer and the positive C layer may be laminated in order from the linear polarizing plate side, or the positive C layer and the λ / 4 layer may be laminated in order from the linear polarizing plate side. May be good. The thickness of the retardation plate is, for example, 0.1 μm or more and 10 μm or less, preferably 0.5 μm or more and 8 μm or less, and more preferably 1 μm or more and 6 μm or less.

The retardation layer may be formed from the resin film exemplified as the material of the above-mentioned thermoplastic resin film, or may be formed from a layer in which the polymerizable liquid crystal compound is cured. The retardation layer may further include an alignment film and a base film, and the λ / 4 layer, the λ / 2 layer, and the positive C layer may be bonded by an interlayer bonding layer described later.

When the retardation layer is formed from a layer obtained by curing a polymerizable liquid crystal compound, the retardation layer can be formed by applying a composition containing the polymerizable liquid crystal compound to a base film and curing the layer. An alignment film may be formed between the base film and the coating layer. As the polymerizable liquid crystal compound, the polymerizable liquid crystal compound described in the above description of the polarizing element can be used. The material and thickness of the base film may be the same as the material and thickness of the thermoplastic resin film. When the retardation layer is formed from a layer obtained by curing a polymerizable liquid crystal compound, the retardation layer may be incorporated into the laminate in the form of having an alignment film and a base film.

The polarizing plate in which the linear polarizing plate and the retardation plate are arranged so that the absorption axis of the linear polarizing plate and the slow axis of the retardation layer are at a predetermined angle has an antireflection function, that is, a circular polarizing plate. Can function as. When the retardation plate includes the λ / 4 layer, the angle formed by the absorption axis of the linear polarizing plate and the slow axis of the λ / 4 layer can be 45 ° ± 10 °. The retardation layer may have a positive wavelength dispersibility or a reverse wavelength dispersibility. The λ / 4 layer preferably has a reverse wavelength dispersibility.
The linear polarizing plate and the retardation plate may be joined by a bonding layer described later.

[Interlayer bonding layer]
The interlayer bonding layer is arranged between the retardation layers, for example, between the first retardation layer and the second retardation layer, and has a function of bonding the first retardation layer and the second retardation layer. The interlayer bonding layer can be composed of an adhesive or a pressure-sensitive adhesive. The interlayer bonding layer is preferably an adhesive layer.

The thickness of the interlayer bonding layer is not particularly limited, but when the pressure-sensitive adhesive layer is used as the interlayer bonding layer, it is preferably 1 μm or more, 5 μm or more, usually 50 μm or less, and 25 μm or less. There may be. When the adhesive layer is used as the interlayer bonding layer, the thickness of the interlayer bonding layer is preferably 0.1 μm or more, may be 0.5 μm or more, is preferably 10 μm or less, and is 5 μm. It may be as follows.

As the pressure-sensitive adhesive used for the interlayer bonding layer, the above-mentioned pressure-sensitive adhesive composition can be used, and other pressure-sensitive adhesives such as (meth) acrylic pressure-sensitive adhesives, styrene-based pressure-sensitive adhesives, and silicones which are different from the materials of the pressure-sensitive adhesive layer are used. It is also possible to use a based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, an epoxy-based copolymer pressure-sensitive adhesive, and the like.

As the adhesive used for the interlayer bonding layer, for example, one or a combination of two or more of water-based adhesives, active energy ray-curable adhesives, and the like can be formed. Examples of the water-based adhesive include a polyvinyl alcohol-based resin aqueous solution, a water-based two-component urethane-based emulsion adhesive, and the like. The active energy ray-curable adhesive is an adhesive that cures by irradiating with active energy rays such as ultraviolet rays, and is, for example, an adhesive containing a polymerizable compound and a photopolymerizable initiator, and an adhesive containing a photoreactive resin. , Adhesives containing a binder resin and a photoreactive cross-linking agent, and the like. Examples of the polymerizable compound include a photopolymerizable monomer such as a photocurable epoxy-based monomer, a photocurable acrylic-based monomer, and a photocurable urethane-based monomer, and an oligomer derived from these monomers. Examples of the photopolymerization initiator include compounds containing substances that generate active species such as neutral radicals, anionic radicals, and cationic radicals by irradiating them with active energy rays such as ultraviolet rays.

[Touch sensor panel]
As the touch sensor panel, the detection method is not limited as long as it is a sensor that can detect the touched position, and the resistance film method, the capacitance coupling method, the optical sensor method, the ultrasonic method, and the electromagnetic induction coupling method are not limited. A touch sensor panel such as a method and a surface acoustic wave method is exemplified. Since the cost is low, a touch sensor panel of a resistance film type or a capacitance coupling type is preferably used. The touch sensor panel can be arranged on the side opposite to the visual side of the laminate.

An example of a resistance film type touch sensor panel is a pair of substrates arranged opposite to each other, an insulating spacer sandwiched between the pair of substrates, and a transparent film provided as a resistance film on the inner front surface of each substrate. It is composed of a conductive film and a touch position detection circuit. In an image display device provided with a resistance film type touch sensor panel, when the surface of the front plate is touched, the opposing resistance films are short-circuited and a current flows through the resistance film. The touch position detection circuit detects the change in voltage at this time, and the touched position is detected.

An example of a capacitance coupling type touch sensor panel is composed of a substrate, a transparent electrode for position detection provided on the entire surface of the substrate, and a touch position detection circuit. In an image display device provided with a capacitance coupling type touch sensor panel, when the surface of the front plate is touched, the transparent electrode is grounded via the capacitance of the human body at the touched point. The touch position detection circuit detects the grounding of the transparent electrode, and the touched position is detected.

[Image display element]
Examples of the image display element include a liquid crystal cell, an organic electroluminescence (organic EL) display element, an inorganic electroluminescence (inorganic EL) display element, a plasma display element, an electroluminescence type display element, and the like.

[Adhesive layer]
The pressure-sensitive adhesive layer is a layer that is interposed between the optical members and adheres them. In the present specification, the "adhesive" is a high-viscosity liquid or a gel-like solid in a state after the curing reaction, and can be adhered by applying a slight pressure at room temperature for a short time, for example, it is also called a pressure-sensitive adhesive. It is a thing. On the other hand, in the present specification, the "adhesive" refers to an adhesive other than an adhesive (pressure sensitive adhesive), and the state after the curing reaction is a solid state, and the elastic modulus range at a temperature of 25 ° C. after curing. Is 100 MPa or more. The pressure-sensitive adhesive layer may be composed of one layer or may be composed of two or more layers, but is preferably composed of one layer.

The shear modulus [MPa] of the pressure-sensitive adhesive layer at a temperature of 25 ° C. may be, for example, 0.5 MPa or less, preferably 0.4 MPa or less, more preferably 0.3 MPa or less, still more preferably 0.2 MPa or less, particularly. It is preferably 0.1 MPa or less. The shear modulus [MPa] of the pressure-sensitive adhesive layer at a temperature of 25 ° C. is usually 0.001 MPa or more, for example 0.005 MPa or more or 0.01 MPa or more. The shear modulus [MPa] of the pressure-sensitive adhesive layer at a temperature of 25 ° C. is measured according to the method described in the column of Examples described later.

The thickness of the pressure-sensitive adhesive layer is preferably 4 μm or more, more preferably 5 μm or more, and further preferably 10 μm or more from the viewpoint of ensuring adhesiveness. The thickness of the pressure-sensitive adhesive layer is preferably 100 μm or less, more preferably 50 μm or less, from the viewpoint of enhancing flexibility. The thickness of the pressure-sensitive adhesive layer shall be the maximum thickness of the pressure-sensitive adhesive layer.

The pressure-sensitive adhesive layer may be composed of a pressure-sensitive adhesive composition containing a resin such as a (meth) acrylic resin, a rubber-based resin, a urethane-based resin, an ester-based resin, a silicone-based resin, or a polyvinyl ether-based resin as a main component. can. Among them, a pressure-sensitive adhesive composition using a (meth) acrylic resin having excellent transparency, weather resistance, heat resistance and the like as a base polymer is preferable. The pressure-sensitive adhesive composition may be an active energy ray-curable type or a thermosetting type.

Examples of the (meth) acrylic resin (base polymer) used in the pressure-sensitive adhesive composition include butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2- (meth) acrylate. A polymer or copolymer having one or more (meth) acrylic acid esters such as ethylhexyl as a monomer is preferably used. It is preferable that the base polymer is copolymerized with a polar monomer. Examples of the polar monomer include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylic acid, hydroxyethyl (meth) acrylate, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, and glycidyl ( Examples thereof include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group and the like, such as meth) acrylate.

The pressure-sensitive adhesive composition may contain only the above-mentioned base polymer, but may further contain a cross-linking agent. The cross-linking agent is a divalent or higher metal ion that forms a carboxylic acid metal salt with a carboxyl group; a polyamine compound that forms an amide bond with a carboxyl group; poly. Examples thereof include epoxy compounds and polyols that form an ester bond with a carboxyl group; polyisocyanate compounds that form an amide bond with a carboxyl group. Of these, polyisocyanate compounds are preferable.

The pressure-sensitive adhesive composition may contain a pressure-sensitive adhesive. Examples of the tackifier include hydrocarbon-based tackifiers, terpene-based tackifiers, rosin-based tackifiers, phenol-based tackifiers, epoxy-based tackifiers, polyamide-based tackifiers, and elastomer-based tackifiers. , Ketone-based adhesives and the like.

Examples of the hydrocarbon-based tackifier include an aliphatic hydrocarbon resin, an aromatic hydrocarbon resin (for example, xylene resin, etc.), an aliphatic cyclic hydrocarbon resin, and an aliphatic / aromatic petroleum resin (for example). , Styrene-olefin copolymer, etc.), aliphatic / alicyclic petroleum resins, hydrogenated hydrocarbon resins, kumaron resins, kumaron-inden resins, and the like.

Examples of the terpene-based tackifier include terpene-based resins such as α-pinene polymers and β-pinene polymers; modified terpenes obtained by modifying terpene-based resins (eg, phenol-modified, aromatic-modified, hydrogenated-modified, etc.). Terpene-based resins (eg, terpene-phenolic resins, styrene-modified terpene-based resins, hydrogenated terpene-based resins, etc.); and the like.

Examples of the rosin-based tackifier include unmodified rosins such as gum rosin and wood rosin (raw rosin); modified rosins obtained by modifying the unmodified rosin by hydrogenation, disproportionation, polymerization, etc. (for example, hydrogenated rosin, non-modified rosin). Normalized rosins, polymerized rosins, other chemically modified rosins, etc.); and various other rosin derivatives; etc.

Examples of the phenol-based tackifier include resol-type or novolak-type alkylphenols.

The active energy ray-curable pressure-sensitive adhesive composition has a property of being cured by being irradiated with active energy rays such as ultraviolet rays and electron beams, and has adhesiveness even before irradiation with active energy rays. It is a pressure-sensitive adhesive composition having a property that it can be brought into close contact with an adherend such as, etc., and can be cured by irradiation with active energy rays to adjust the adhesion force. The active energy ray-curable pressure-sensitive adhesive composition is preferably an ultraviolet-curable type. The active energy ray-curable pressure-sensitive adhesive composition further contains a base polymer and an active energy ray-polymerizable compound. Further, if necessary, a photopolymerization initiator, a photosensitizer, or the like may be contained.

The pressure-sensitive adhesive composition includes fine particles for imparting light scattering properties, beads (resin beads, glass beads, etc.), glass fibers, resins other than the base polymer, fillers (metal powder, other inorganic powder, etc.), and antioxidants. Additives such as agents, UV absorbers, dyes, pigments, colorants, antifoaming agents, corrosion inhibitors, photopolymerization initiators and the like can be included.

The pressure-sensitive adhesive layer can be formed by applying the pressure-sensitive adhesive composition onto a substrate. When the active energy ray-curable pressure-sensitive adhesive composition is used, the formed first pressure-sensitive adhesive layer can be irradiated with active energy rays to obtain a cured product having a desired degree of curing.

[Other layers]
As the other layer, the laminated body 100 can include a bonding layer for bonding a linear polarizing plate and a retardation plate.

[Lated layer]
The laminated body 100 may further include a laminating layer for laminating the linear polarizing plate and the retardation plate. The laminating layer can be formed from an adhesive or an adhesive. As the adhesive and the pressure-sensitive adhesive, those exemplified in the above-mentioned interlayer bonding layer can be used.

[Manufacturing method of laminated body]
The method for producing the laminate can include a step of laminating the optical members using the pressure-sensitive adhesive layer having a tack value of 0.8 gf or more at a temperature of 25 ° C. The above description of the pressure-sensitive adhesive layer applies to the tack value of the pressure-sensitive adhesive layer, the shear modulus and thickness at a temperature of 25 ° C., and the pressure-sensitive adhesive composition.

In order to improve the adhesion, it is preferable to apply a surface activation treatment such as corona treatment or plasma treatment to one or both of the bonded surfaces.

The pressure-sensitive adhesive layer can be prepared as a pressure-sensitive adhesive sheet. For the pressure-sensitive adhesive sheet, for example, a layer made of a pressure-sensitive adhesive is formed in the form of a sheet on a release film (hereinafter, also referred to as a separator) that has been subjected to a mold release treatment, and another release film is attached on the pressure-sensitive adhesive layer. It can be manufactured by a matching method or the like. Each layer can be bonded by a method in which an adhesive sheet from which one release film has been peeled off is attached to one layer, then the other release film is peeled off, and the other layer is attached.

The method for producing the laminate can include, for example, the following steps (a) to (d). A method for manufacturing the laminate will be described with reference to FIG.
(A) A front plate laminate 30 composed of a release film 31, a front plate 32 and a release film 33, and an adhesive sheet 40 composed of a light separator 41, a first adhesive layer 42 and a heavy separator 43 are prepared, and the front plate is laminated. The surface from which the release film 33 has been peeled off from one surface of the body 30 and the surface from which the light separator 41 of the adhesive sheet 40 has been peeled off are subjected to corona treatment and bonded together to form the release film 31, the front plate 32, and the first adhesive. A step of obtaining a laminated body 200 having a layer 42 and a heavy separator 43 in this order [FIG. 2 (a)].

(B) A circularly polarizing plate laminate 50 composed of a release film 51, a circularly polarizing plate 52, and a release film 53 is prepared, a surface from which the heavy separator 43 is peeled off from the laminate 200, and a release film 51 from the circularly polarizing plate laminate 50. A step of corona-treating the peeled surface and then laminating to obtain a laminated body 210 having a peeling film 31, a front plate 32, a first pressure-sensitive adhesive layer 42, a circularly polarizing plate 52, and a peeling film 53 in this order. [Fig. 2 (b)].

(C) An adhesive sheet 60 composed of a light separator 61, a second adhesive layer 62, and a heavy separator 63 was prepared, and the surface from which the release film 53 was peeled off from the laminate 210 and the light separator 61 from the adhesive sheet 60 were peeled off. A laminated body having a release film 31, a front plate 32, a first pressure-sensitive adhesive layer 42, a circular polarizing plate 52, a second pressure-sensitive adhesive layer 62, and a heavy separator 63 in this order after being subjected to corona treatment on the surface. Step of obtaining 220 [FIG. 2 (c)].

(D) A touch sensor layer 70 with a PET film is prepared, the PET film 71 with an adhesive is peeled off from the touch sensor layer 70 with a PET film, and the surface from which the heavy separator 63 is peeled off from the laminate 220 is subjected to corona treatment. A laminate having a surface and a touch sensor layer 72 bonded together and having a release film 31, a front plate 32, a first adhesive layer 42, a circular polarizing plate 52, a second adhesive layer 62, and a touch sensor layer 72 in this order. After obtaining the body 230, the release film 31 is peeled off from the laminated body 230, and the front plate 32, the first pressure-sensitive adhesive layer 42, the circular plate plate 52, the second pressure-sensitive adhesive layer 62, and the touch sensor layer 72 are provided in this order. Step of obtaining the laminated body 240 [FIG. 2 (d)].

<Image display device>
The image display device according to the present invention includes the above-mentioned laminated body. The image display device is not particularly limited, and examples thereof include an image display device such as an organic EL display device, an inorganic EL display device, a liquid crystal display device, and an electroluminescence display device. The image display device may have a touch panel function. The laminate is suitable for a flexible image display device capable of bending or bending. In the image display device, when the laminate has a front plate, the laminate is arranged on the visual side of the image display device with the front plate facing the outside (the side opposite to the image display element side, that is, the visual recognition side). ..

The image display device according to the present invention can be used as a mobile device such as a smartphone or tablet, a television, a digital photo frame, an electronic signboard, a measuring instrument or an instrument, an office device, a medical device, a computer device or the like. The image display device according to the present invention has excellent flexibility and is therefore suitable for a flexible display or the like.

Hereinafter, the present invention will be described in more detail by way of examples. Unless otherwise specified, "%" and "part" in the example are mass% and parts by mass.

[Measurement of thickness]
The measurement was performed using a contact type film thickness measuring device (“MS-5C” manufactured by Nikon Corporation). However, the polarizing element, the retardation layer and the alignment film were measured using a laser microscope (LEXT, manufactured by Olympus Corporation).

[Measurement of tack value at a temperature of 25 ° C]
The tack value of the pressure-sensitive adhesive layer at a temperature of 25 ° C. was measured using Texture Analyzer (STABLE MICRO SYSTEMS). The procedure for measuring the tack value at a temperature of 25 ° C. will be described with reference to FIG. First, in the joining step [FIG. 3 (A)], the release film was peeled off from the same adhesive sheet used in Examples and Comparative Examples and allowed to stand, and at room temperature (25 ° C.), a stainless steel cylinder having a diameter of 5 mm was allowed to stand. The 300 was brought close to the surface of the exposed pressure-sensitive adhesive layer 301, pressed against the surface, and then maintained for 1 second with a bonding force under a load of 100 g (contact area: 19.6 mm ² ). After joining, in the peeling step [FIG. 3 (B)], when the stainless cylinder 300 is lifted at a speed of 60 mm / min and the measured peeling force is maximized, the measured value in [FIG. 3 (C)]. Was used as the tack value. The tack value of the pressure-sensitive adhesive layer at a temperature of 25 ° C. was measured 24 hours after the pressure-sensitive adhesive layer was prepared.

[Measurement of shear modulus at a temperature of 25 ° C]
The shear modulus of the pressure-sensitive adhesive layer at a temperature of 25 ° C. was measured using a viscoelasticity measuring device (MCR-301, Antonio Par). The same adhesive sheet used in the examples and comparative examples is made to have a width of 20 mm and a length of 20 mm, the release film is peeled off, a plurality of sheets are laminated so as to have a thickness of 150 μm, bonded to a glass plate, and then bonded to the measurement chip. The measurement was carried out under the conditions of a frequency of 1.0 Hz, a deformation amount of 1%, and a heating rate of 5 ° C./min in a temperature range of −20 ° C. to 100 ° C., and the shear modulus at a temperature of 25 ° C. was confirmed. The shear modulus of the pressure-sensitive adhesive layer at a temperature of 25 ° C. was measured 24 hours after the pressure-sensitive adhesive layer was prepared.

[Evaluation of static bending durability]
FIG. 4 shows a method of a static bending durability test (mandrel bending test). First, the laminate was cut into 1 cm × 10 cm test pieces. The laminated body 401 was placed on the test plate 400 with the front plate side facing down, and an iron rod 402 having a diameter of 5 mm was placed on the laminated body 401 [FIG. 4 (A)]. The test piece was manually folded and fixed together with the test plate 400 so that the front plate was on the outside [FIG. 4 (B)]. While maintaining this state, the maximum time during which no bubbles were generated between the circularly polarizing plate and the pressure-sensitive adhesive layer or in the pressure-sensitive adhesive layer was measured.
A: No bubbles are generated within 72 hours.
B: Bubbles are generated within 72 hours over 48 hours.
C: Bubbles are generated within 24 hours and 48 hours.
D: Bubbles are generated within 24 hours.

[Manufacturing of adhesive sheets C1 to C8]
2-Ethylhexyl acrylate (2-EHA) and n-butyl acrylate (n-BA) shown in Table 1 were placed in a 1 L reactor equipped with a cooling device so that the nitrogen gas could recirculate and the temperature could be easily controlled. , Beta carboxyethyl acrylate (B-CEA), acrylic acid (AA), glycidyl methacrylate (GMA), 2-hydroxyethyl methacrylate (2-HEMA) was added. After refluxing the nitrogen gas for 1 hour to remove oxygen, the solution was maintained at 60 ° C. After uniformly mixing the above-mentioned monomer mixture, the photopolymerization initiator benzyldimethylketal (I-651) and 1-hydroxycyclohexylphenylketone (I-184) were added in the blending amounts shown in Table 1. The (meth) acrylic resins A1 to A8 were produced by irradiating with a UV lamp (10 mW) while stirring. The obtained (meth) acrylic resins A1 to A8, the compounds T1 to T3, and the 1-hydroxycyclohexylphenyl ketone (I-184) were mixed in the amounts shown in Table 1 to obtain the pressure-sensitive adhesive compositions B1 to B8. Manufactured. The pressure-sensitive adhesive compositions B1 to B8 are applied on a release film A (polyethylene terephthalate film, thickness 38 μm) coated with a silicon release agent so as to have a thickness of 25 μm, and the release film B (polyethylene terephthalate film, A thickness of 38 μm) was bonded, and UV irradiation was performed to prepare pressure-sensitive adhesive sheets C1 to C8 composed of a release film A / an adhesive layer / a release film B. The tack value and the shear modulus at a temperature of 25 ° C. were measured 24 hours after the pressure-sensitive adhesive sheets C1 to C8 were prepared. The UV irradiation conditions were an integrated light intensity of 400 mJ / cm ² and an illuminance of 1.8 mW / cm ² (UVV standard).

The abbreviations in Table 1 have the following meanings.
2-EHA: 2-Ethylhexyl acrylate (Tokyo Chemical Industry Co., Ltd.)
BA: Butyl acrylate (Tokyo Chemical Industry Co., Ltd.)
B-CEA: Beta Carcinoembrylic Acid Acrylate (Sigma-Aldrich, USA)
AA: Acrylic acid (Tokyo Chemical Industry Co., Ltd.)
GMA: Glycydyl methacrylate (Sigma-Aldrich, USA)
2-HEMA: 2-Hydroxyethyl methacrylate (Tokyo Chemical Industry Co., Ltd.)
I-651: Benzyldimethylketal (BASF)
I-184: 1-Hydroxycyclohexylphenylketone (BASF)
T1: 3,3,5-trimethylcyclohexyl acrylate (Miramer M1130, Miwon specialty chemical, Korea)
T2: Lauryl acrylate (Miramer M120, Miwon specialty chemical, South Korea)
T3: Phenolic (EO) acrylate (Miramer M140, Miwon specialty chemical, South Korea)

<Example 1>
(Preparation of front plate)
One surface of a transparent base film (polyamide-imide film, thickness 40 μm) prepared according to Example 4 of JP-A-2018-119141 is coated with the following composition for a hard coat layer, and then the solvent is dried to obtain UV. By curing, a front plate (thickness 50 μm) having a hard coat layer having a thickness of 10 μm formed on one side of the base film was produced.
[Composition for forming a hard coat layer]
30 parts by mass of multifunctional acrylate (MIWON Specialty Chemical, MIRAMER M340), 50 parts by mass of nanosilica sol (particle size 12 nm, solid content 40%) dispersed in propylene glycol monomethyl ether, 17 parts by mass of ethyl acetate, photopolymerization initiator ( BASF, I184) 2.7 parts by mass, fluorine-based additive (Shinetsu Chemical Industry Co., Ltd., KY1203) 0.3 parts by mass are mixed using a stirrer and filtered using a polypropylene (PP) material filter. Manufactured by

(Preparation of circularly polarizing plate)
A polyvinyl alcohol (PVA) film having an average degree of polymerization of about 2,400, a saponification degree of 99.9 mol% or more, and a thickness of 20 μm was prepared. After immersing the PVA film in pure water at 30 ° C, it was immersed in an aqueous solution having an iodine / potassium iodide / water mass ratio of 0.02 / 2/100 at 30 ° C to perform iodine dyeing (iodine dyeing step). .. The PVA film that had undergone the iodine dyeing step was immersed in an aqueous solution having a mass ratio of potassium iodide / boric acid / water of 12/5/100 at 56.5 ° C. to perform boric acid treatment (boric acid treatment step). .. The PVA film that had undergone the boric acid treatment step was washed with pure water at 8 ° C. and then dried at 65 ° C. to obtain a substituent in which iodine was adsorbed and oriented on polyvinyl alcohol. The PVA film was stretched in the iodine dyeing step and the boric acid treatment step. The total draw ratio of the PVA film was 5.3 times. The thickness of the obtained polarizing element was 7 μm.

A nip roll of the polarizing element obtained above and a cycloolefin polymer (COP) film having a thickness of 13 μm (ZF-14, manufactured by Nippon Zeon Corporation, having an in-plane retardation value of 1 nm at a wavelength of 550 nm) via a water-based adhesive. I pasted them together. While maintaining the tension of the obtained laminate at 430 N / m, it was dried at 60 ° C. for 2 minutes to obtain a linear polarizing plate having a COP film on one side. The water-based adhesive is 100 parts by mass of water, 3 parts by mass of carboxyl group-modified polyvinyl alcohol (“Kuraray Poval KL318”, manufactured by Kuraray Co., Ltd.), and a water-soluble polyamide epoxy resin (“Smiley's Resin 650” (solid content concentration). It was prepared by adding (30% aqueous solution)) and 1.5 parts by mass (manufactured by Taoka Chemical Industry Co., Ltd.).

The polarizing element side of the linear polarizing plate and the retardation layer were bonded to each other via an acrylic pressure-sensitive adhesive layer having a thickness of 5 μm. The retardation layer has a thickness of 5 μm, and the layer structure includes a λ / 2 layer (thickness 2 μm) including a layer in which the liquid crystal compound is cured, a UV curable adhesive layer (thickness 2 μm), and a layer in which the liquid crystal compound is cured. It was a λ / 4 layer (thickness 1 μm). In this way, a circularly polarizing plate (thickness 30 μm, layer structure: COP film / modulator / retardation layer) was produced.

(Preparation of touch sensor laminate)
A glass plate was coated with an acrylic resin to form a separation layer. Next, a translucent electrode layer was formed on the separation layer, and a touch sensor layer (thickness 7 μm) composed of the translucent electrode layer and the separation layer was produced. Then, the release film A was laminated on the side opposite to the separation layer side of the translucent electrode layer. The release film B was laminated on the surface from which the glass plate was removed to prepare a touch sensor laminate having a layer structure of the release film A / touch sensor layer / release film B.

(Preparation of laminated body)
The pressure-sensitive adhesive sheet shown in Table 2 was used as the pressure-sensitive adhesive layer, and the above members were bonded together to prepare a laminated body. This laminate consists of a front plate (thickness 50 μm), a first pressure-sensitive adhesive layer (thickness 25 μm), a circularly polarizing plate (thickness 30 μm), a second pressure-sensitive adhesive layer (thickness 25 μm), and a touch sensor layer (thickness 7 μm) in this order. Including, the total thickness was 137 μm. When the members were bonded together, the bonded surface was subjected to corona treatment. The prepared laminate was allowed to stand in an environment with a temperature of 23 ° C. and a relative humidity of 55% for 24 hours, and then the static bending durability of the laminate was evaluated. The results are shown in Table 2.

<Example 2 and Comparative Examples 1 to 5>
A laminate was prepared in the same procedure as in Example 1 except that the pressure-sensitive adhesive sheets shown in Table 2 were used for the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer. The static bending durability of the laminated body was evaluated. The time from the preparation of the pressure-sensitive adhesive layer to the evaluation of the static bending durability was the same as that in Example 1. The results are shown in Table 2.

100,200,210,220,230,240,401 Laminate, 110 First Optical Film, 120 First Adhesive Layer, 130 Second Optical Member, 140 Second Adhesive Layer, 150 Third Optical Member, 30 Front Face plate laminate, 31, 33, 51, 53 release film, 32 front plate, 40, 60 adhesive sheet, 41, 61 light separator, 42 first adhesive layer, 43, 63 double separator, 50-yen polarizing plate laminate , 52 circular polarizing plate, 62 second adhesive layer, 70 touch sensor layer with PET film, 71 PET film with adhesive, 72 touch sensor layer, 300 cylinders, 301 adhesive layer, 400 test plate, 402 iron rod

Claims (8)

A laminate including a first optical member, a first pressure-sensitive adhesive layer, a second optical member, a second pressure-sensitive adhesive layer, and a third optical member in this order.
The tack value of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer at a temperature of 25 ° C. is 0.8 gf or more.
A laminated body satisfying the formula (1).
Tack value at a temperature of 25 ° C. of the second pressure-sensitive adhesive layer> Tack value at a temperature of 25 ° C. of the first pressure-sensitive adhesive layer (1) The laminate according to claim 1, wherein both the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer have a tack value of 10.0 gf or less at a temperature of 25 ° C. The laminate according to claim 1 or 2, wherein the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer both have a shear modulus of 0.5 MPa or less at a temperature of 25 ° C. The laminate according to any one of claims 1 to 3, wherein the first optical member is a front plate. The laminate according to any one of claims 1 to 4, wherein the second optical member is a polarizing plate. The laminate according to any one of claims 1 to 5, wherein the third optical member is a touch sensor panel. An image display device including the laminate according to any one of claims 1 to 6. The method for manufacturing a laminated body according to claim 1.
A method for producing a laminated body, which comprises a step of bonding optical members using an adhesive layer having a tack value of 0.8 gf or more at a temperature of 25 ° C.

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