WO2021149359A1

WO2021149359A1 - Optical stack and display device

Info

Publication number: WO2021149359A1
Application number: PCT/JP2020/044457
Authority: WO
Inventors: 大山姜
Original assignee: 住友化学株式会社
Priority date: 2020-01-24
Filing date: 2020-11-30
Publication date: 2021-07-29
Also published as: JP2021117334A; KR20220126711A; CN115003499A; TW202129319A

Abstract

Provided is an optical stack used while being disposed on the front surface of a display device and having excellent impact resistance. The optical stack comprises a front surface plate containing a base material, and n optical members (n representing an integer of 2 or greater), which are layered in this order. An adhesive layer, having a thickness of 10 μm or thicker, is layered on the surface of each of the n optical members on the front surface plate side thereof such that same contact each other. When an optical member at the xth position (x representing an integer of between 1 and n inclusive) from the front surface plate side is defined as the xth optical member, an evaluation value A satisfies the relationship in formula (2): (2) 50 ≤ A ≤ 500

Description

Optical laminate and display device

The present invention relates to an optical laminate and a display device.

Korean Publication No. 2018-0012913 (Patent Document 1) describes that a window for a display device having excellent durability is provided.

Korean Publication No. 2018-0012913

An object of the present invention is to provide an optical laminate used by arranging it on the front surface of a display device, which has excellent impact resistance, and a display device including the optical laminate.

The present invention provides an optical laminate and a display device illustrated below.
[1] An optical laminate in which a front plate including a base material and n (n is an integer of 2 or more) optical members are laminated in this order.
Adhesive layers having a thickness of 10 μm or more are in contact with each other and laminated on the surface of the n optical members on the front plate side.
Assuming that the xth optical member (x is an integer of 1 or more and n or less) from the side closer to the front plate is the xth optical member, the evaluation value A calculated by the following formula (1) is the following formula (2):
50 ≤ A ≤ 500 (2)
An optical laminate that satisfies the relationship.

[In the formula (1), T ₀ [mJ / mm ³ ] is the toughness of the front plate, and a ₀ is (thickness of the base material [μm]) / (thickness of the front plate [μm]). , T _x [mJ / mm ³ ] is the toughness of the xth optical member, and a _x is (from the surface of the front plate opposite to the optical member side to the front plate side of the x optical member. Distance to the surface [μm]) / (thickness of the xth optical member [μm]). ]
[2] The optical laminate according to [1], wherein one of the n optical members is a polarizing plate.
[3] The optical laminate according to [1] or [2], wherein one of the n optical members is a touch sensor panel.
[4] The optical laminate according to any one of [1] to [3], wherein n is an integer of 4 or less.
[5] A display device including the optical laminate according to any one of [1] to [4].

According to the present invention, it is possible to provide an optical laminate having excellent impact resistance and a display device including the optical laminate.

It is the schematic sectional drawing which shows an example of the optical laminated body which concerns on this invention.

Hereinafter, embodiments of the optical laminate according to 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 scale is appropriately adjusted to make it easier to understand each component, and the scale of each component shown in the drawings does not necessarily match the scale of the actual component.

[Optical laminate]
The optical laminate according to the present invention is an optical laminate in which a front plate including a base material and n (n is an integer of 2 or more) optical members are laminated in this order, and the n optics are described. Adhesive layers having a thickness of 10 μm or more are in contact with each other and laminated on the surface of the member on the front plate side. Regarding the optical laminate according to the present invention, in the present specification, the x-th (x is an integer of 1 or more and n or less) optical member from the side closer to the front plate is defined as the x-th optical member, and the front plate of the x-optical member. The pressure-sensitive adhesive layer having a thickness of 10 μm or more and laminated in contact with the side surface is defined as the xth pressure-sensitive adhesive layer. n is preferably an integer of 6 or less, and more preferably an integer of 4 or less.

Each optical member may be composed of one layer or may be composed of a plurality of layers. In the present specification, whether an optical member composed of a plurality of layers is to be a plurality of optical members or one optical member is determined based on the presence or absence of an adhesive layer having a thickness of 10 μm or more. In the present specification, the two portions separated by the pressure-sensitive adhesive layer having a thickness of 10 μm or more are different optical members. Therefore, each optical member may include a pressure-sensitive adhesive layer having a thickness of less than 10 μm, while each optical member does not include a pressure-sensitive adhesive layer having a thickness of 10 μm or more.

The thickness of the optical laminate according to the present invention is not particularly limited because it varies depending on the function required for the optical laminate, the application of the optical laminate, etc., but is, for example, 50 μm or more and 4000 μm or less, preferably 70 μm or more and 2000 μm or less. Yes, more preferably 100 μm or more and 1000 μm or less.

The plan view shape of the optical laminate may be, for example, a square shape, preferably a square shape having a long side and a short side, and more preferably a rectangle. When the shape of the optical laminate 100 in the plane direction is rectangular, the length of the long side may be, for example, 10 mm or more and 1400 mm or less, preferably 50 mm or more and 600 mm or less. The length of the short side is, for example, 5 mm or more and 800 mm or less, preferably 30 mm or more and 500 mm or less, and more preferably 50 mm or more and 300 mm or less. Each layer constituting the optical laminate 100 may have corners R-processed, end portions notched, or perforated.

The optical laminate can be used, for example, in a display device or the like. The 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 electroluminescent display device. The optical laminate 100 is particularly suitable for a display device capable of bending.

FIG. 1 is a schematic cross-sectional view of an optical laminate according to an embodiment of the present invention. The optical laminate 100 shown in FIG. 1 is configured by laminating a front plate 10 and three (n = 3) optical members in this order. The three optical members are the first optical member 21, the second optical member 22, and the third optical member 23 from the side closer to the front plate 10. In the optical laminate 100, the first adhesive layer 31 is in contact with and laminated on the surface of the first optical member 21 on the front plate 10 side, and the second optical member 22 is laminated on the surface of the second optical member 22 on the front plate 10 side. The pressure-sensitive adhesive layer 32 is in contact and laminated, and the third pressure-sensitive adhesive layer 33 is in contact and laminated on the surface of the third optical member 23 on the front plate 10 side. The first to third pressure-sensitive

adhesive layers

31, 32, and 33 all have a thickness of 10 μm or more.

In the optical laminate 100, the front plate 10 includes the base material 11, and further includes a hard coat layer 12 provided on the surface of the base material 11 opposite to the first optical member 21 side. For example, in the optical laminate 100, the first optical member 21 is a protective plate, the second optical member 22 is a polarizing plate, and the third optical member 23 is a touch sensor panel.

<Evaluation value A of optical laminate>
The evaluation value A of the optical laminate according to the present invention is the following formula (2):
50 ≤ A ≤ 500 (2)
Satisfy the relationship.

The evaluation value A is the following formula (1):

It is a value calculated by.

In the formula (1), T ₀ [mJ / mm ³ ] is the toughness of the front plate, and a ₀ is (thickness of the base material contained in the front plate [μm]) / (thickness of the front plate [μm]). Yes, T _x [mJ / mm ³ ] is the toughness of the xth optical member, and a _x is (the distance from the surface of the front plate opposite to the optical member side to the surface of the front plate side of the xth optical member). [Μm]) / (thickness of the xth optical member [μm]). In the present specification, toughness means a value measured in an environment of a temperature of 23 ° C. and a relative humidity of 55%. Toughness is measured by the methods described in the Examples below.

In the optical laminate shown in FIG. 1, the evaluation value A is the formula (1a):
A = T ₀ / a ₀ + T ₁ / a ₁ + T ₂ / a ₂ + T ₃ / a ₃ (1a)
It is a value calculated by.

In equation (1a),
T ₀ [mJ / mm ³ ] is the toughness of the front plate 10.
a ₀ _{is (thickness t 01} [μm] of the base material 11 contained in the front plate 10 _{) / (thickness t 0} [μm] of the front plate 10).
T ₁ [mJ / mm ³ ] is the toughness of the first optical member 21.
a ₁ is (distance from the surface of the front plate 10 opposite to the optical member side to the surface of the first optical member 21 on the front plate 10 side d ₁ [μm]) / (thickness of the first optical member 21 t _1). [Μm]), and T ₂ [mJ / mm ³ ] is the toughness of the second optical member 22.
a ₂ is (distance from the surface of the front plate 10 opposite to the optical member side to the surface of the second optical member 22 on the front plate 10 side d ₂ [μm]) / (thickness t _{2 of the second optical member 22).} [Μm]), and T ₃ [mJ / mm ³ ] is the toughness of the third optical member 23.
a ₃ is (distance from the surface of the front plate 10 opposite to the optical member side to the surface of the third optical member 23 on the front plate 10 side d ₃ [μm]) / (thickness of the third optical member 23 t _3). [Μm]).

The evaluation value A is a value calculated by the formula (1) derived based on the result of the preliminary test described later. As can be seen from the equation (1), the evaluation value A becomes larger as the toughness of the front plate is larger and as the thickness of the front plate is thicker. Further, the evaluation value A becomes larger as the toughness of the xth optical member is larger and as the thickness of the xth optical member is thicker. The contribution of toughness and thickness to the evaluation value A is greatest in the front plate, and for the xth optical member, the distance from the front plate is included in the denominator of equation (1), so the position is close to the front plate. The larger the value is, the larger the value of x is. Therefore, the evaluation value A can be adjusted by appropriately adjusting the toughness and thickness of the front plate, the toughness and thickness of the xth optical member, the number of optical members (value of n), the thickness of the adhesive layer, and the like. can. The toughness of the front plate and the toughness of the xth optical member can be adjusted by adjusting these materials.

The optical laminate according to the present invention can improve impact resistance when the evaluation value A is 50 or more. The impact resistance of the optical laminate can be evaluated by the method described in Examples described later. The optical laminate according to the present invention preferably has an evaluation value A of 100 or more from the viewpoint of further improving impact resistance.

Further, the optical laminate according to the present invention can improve the bending resistance when the evaluation value A is 500 or less. It is preferable that the optical laminate can be bent in the direction in which the front plate is inward. Bendable means that the front plate can be bent inward. In the present specification, the bending includes a form of bending in which a curved surface is formed in the bent portion, and the bending radius of the bent inner surface is not particularly limited. Bending also includes refraction with an inner surface refraction angle greater than 0 degrees and less than 180 degrees, and folding with an inner surface bending radius close to zero or an inner surface refraction angle of 0 degrees. The bending resistance can be evaluated by whether or not cracks occur in any layer of the optical laminate when bending is repeated. The optical laminate according to the present invention preferably has an evaluation value A of 300 or less, and may be 200 or less, from the viewpoint of further improving bending resistance.

<Front plate>
The front plate can form the outermost surface of the display device. The material and thickness of the front plate are not limited as long as it is a plate-like body capable of transmitting light. The front plate may be composed of only the base material, or may be composed of the base material and other layers as long as it contains the base material. The base material and the other layers may each be composed of only one layer, or may be composed of two or more layers. Examples of the base material contained in the front plate include a resin plate-like body (for example, a resin plate, a resin sheet, a resin film, etc.) and a glass plate-like body (for example, a glass plate, a glass film, etc.).

The front plate may be a resin film provided with a hard coat layer from the viewpoint of hardness. The hard coat layer may be formed on one surface of the resin film or may be formed on both sides. By providing the hard coat layer, hardness and scratch resistance can be improved. The hard coat layer is, for example, a cured layer of an ultraviolet curable resin. Examples of the ultraviolet curable resin include acrylic resin, silicone resin, polyester resin, urethane resin, amide resin, epoxy resin and the like. The hard coat layer may contain additives to improve strength. The additive is not particularly limited, and examples thereof include inorganic fine particles, organic fine particles, or a mixture thereof. When the hard coat layers are provided on both sides of the resin film, the composition and thickness of the hard coat layers may be the same as each other or different from each other.

Front plate from easily form an optical laminate having excellent impact resistance standpoint, it is preferable that toughness is 10 mJ / mm ³ or more, still more preferably 30 mJ / mm ³ or more, 40 mJ / mm ³ The above is the most preferable. Toughness of the front plate, for example 100 mJ / mm ³ or less, may be 60 mJ / mm ³ or less. The thickness of the front plate may be, for example, 30 μm or more and 500 μm or less, preferably 40 μm or more and 200 μm or less, and more preferably 50 μm or more and 100 μm or less. The thickness of the front plate is preferably 40 μm or more from the viewpoint of easily forming an optical laminate having excellent impact resistance. In the present invention, the thickness of each layer constituting the optical laminate can be measured according to the thickness measuring method described in Examples described later.

When the base material of the front plate is a resin plate-like body, the resin plate-like body is not limited as long as it can transmit light. Examples of the resin constituting the resin plate-like body include triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, polyester, polystyrene, polyamide, and polyether. Iimide, poly (meth) acrylic, polyimide, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polyethersulfone , Polymethylmethacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyamideimide and other polymers. These polymers can be used alone or in combination of two or more. From the viewpoint of improving strength and transparency, the resin plate-like body is preferably a resin film formed of a polymer such as polyimide, polyamide, or polyamideimide. The thickness of the resin plate-like body is preferably 30 μm or more, for example, 200 μm or less, from the viewpoint of easily forming an optical laminate having excellent impact resistance.

When the base material of the front plate is a glass plate, tempered glass for a display is preferably used as the glass plate. The thickness of the glass plate may be, for example, 20 μm or more and 1000 μm or less.
By using a glass plate, a front plate having excellent mechanical strength and surface hardness can be constructed.

When the optical laminate is used in a display device, the front plate not only has a function of protecting the front surface (screen) of the display device (function as a window film), but also functions as a touch sensor, a blue light cut function, and so on. It may have a viewing angle adjusting function or the like.

<Xth adhesive layer>
The first pressure-sensitive adhesive layer is interposed between the front plate and the first optical member, and these are bonded together. The xth pressure-sensitive adhesive layer excluding the first pressure-sensitive adhesive layer is interposed between the x-1th optical member and the xth optical member, and these are bonded to each other. The xth pressure-sensitive adhesive layer may be composed of one layer or two or more layers as long as the thickness is 10 μm or more, but is preferably composed of one layer. The first to n pressure-sensitive adhesive layers may be the same or different in the composition, compounding components, thickness, etc. of the pressure-sensitive adhesive composition.

The xth pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive composition containing (meth) acrylic resin, rubber-based resin, urethane-based resin, ester-based resin, silicone-based resin, and polyvinyl ether-based resin as main components (base polymer). be able to. As the pressure-sensitive adhesive composition constituting the x-th pressure-sensitive adhesive layer, 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 suitable. The pressure-sensitive adhesive composition may be an active energy ray-curable type or a thermosetting type.

Examples of the (meth) acrylic resin used in the pressure-sensitive adhesive composition include (meth) butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. A polymer or copolymer containing one or more acrylates 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 compound, (meth) acrylic acid 2-hydroxypropyl compound, (meth) acrylic acid hydroxyethyl compound, (meth) acrylamide compound, and N, N-dimethylaminoethyl (meth) acrylate compound. , A monomer having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, etc., such as a glycidyl (meth) acrylate compound.

The pressure-sensitive adhesive composition may contain only the above-mentioned base polymer, but usually further contains a cross-linking agent. The cross-linking agent is a metal ion having a divalent value or higher and forming a carboxylic acid metal salt with the carboxyl group, a polyamine compound forming an amide bond with the carboxyl group, and a carboxyl group. Examples thereof include polyepoxy compounds or polyols that form an ester bond with, and polyisocyanate compounds that form an amide bond with a carboxyl group. The cross-linking agent is preferably a polyisocyanate compound.

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, such as a film. It has the property that it can be brought into close contact with the adherend of the above, and can be cured by irradiation with active energy rays to adjust the adhesion. 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 an active energy ray-polymerizable compound in addition to the base polymer and the cross-linking agent. If necessary, a photopolymerization initiator, a photosensitizer, or the like may be contained.

The active energy ray-polymerizable compound is, for example, a (meth) acrylate monomer having at least one (meth) acryloyloxy group in the molecule; obtained by reacting two or more kinds of functional group-containing compounds, and at least 2 in the molecule. (Meta) acrylic compounds such as (meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers having one (meth) acryloyloxy group, and compounds having at least two benzoylphenylmethacryloyl groups in the molecule. Can be mentioned. The pressure-sensitive adhesive composition can contain 0.1 part by mass or more of the active energy ray-polymerizable compound with respect to 100 parts by mass of the solid content of the pressure-sensitive adhesive composition, and is 10 parts by mass or less, 5 parts by mass or less, or 2 parts by mass. Can include less than one copy.

Benzoylphenylmethacryloyl group means a group represented by the following structure. * Represents a bond. The number of benzoylphenylmethacryloyl groups contained in the molecule of the active energy ray-polymerizable compound can be 5 or less, and can be 4 or less.

Examples of the compound having at least two benzoylphenyl metaacryloyl groups in the molecule include the following compounds.

Examples of the photopolymerization initiator include benzophenone, benzyl dimethyl ketal, 1-hydroxycyclohexylphenyl ketone and the like. The photopolymerization initiator may contain one kind or two or more kinds. When the pressure-sensitive adhesive composition contains a photopolymerization initiator, the total content thereof may be, for example, 0.01 part by mass or more and 3.0 parts by mass or less with respect to 100 parts by mass of the solid content of the pressure-sensitive adhesive composition.

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, pressure-sensitive imparting agents, and fillers (metal powders and other inorganic powders). Etc.), antioxidants, UV absorbers, dyes, pigments, colorants, antifoaming agents, corrosion inhibitors, photopolymerization initiators and other additives can be included.

The xth pressure-sensitive adhesive layer can be formed by applying an organic solvent diluent of the above-mentioned pressure-sensitive adhesive composition on a substrate and drying it. The xth pressure-sensitive adhesive layer can also be formed by using a pressure-sensitive adhesive sheet formed by using the pressure-sensitive adhesive composition. When the active energy ray-curable pressure-sensitive adhesive composition is used, the formed pressure-sensitive adhesive layer can be irradiated with active energy rays to obtain a pressure-sensitive adhesive layer having a desired degree of curing.

The thickness of the xth pressure-sensitive adhesive layer is 10 μm or more, preferably 100 μm or less, and more preferably 50 μm or less.

<Optical member>
Examples of the optical member in the optical laminate include a protective plate, a polarizing plate, a touch sensor panel, and the like as included in the optical laminate 100 shown in FIG. 1, and a back plate and the like. Examples of the back plate include a touch sensor panel, an organic EL display element, and the like. When the optical member is composed of a plurality of layers, a bonding layer for bonding the two layers can be included. The stacking order of the optical members in the optical laminate is, for example, a protective plate / polarizing plate / touch sensor panel (lamination order shown in FIG. 1), a protective plate / polarizing plate / touch sensor panel / organic EL display from the front plate side. Elements, protective plates / touch sensor panels / polarizing plates, protective plates / touch sensor panels / polarizing plates / organic EL display elements, and the like can be mentioned. The polarizing plate in the stacking order shown here is preferably a circular polarizing plate in that it can impart a function as an antireflection film to the optical laminated body. The protective plate in the stacking order shown here may not be included, and is preferably included from the viewpoint that the evaluation value A can be easily adjusted to a desired value.

≪Polarizing plate≫
The polarizing plate may be, for example, a linear polarizing plate, a circular polarizing plate (including an elliptical polarizing plate), or the like. The circular polarizing plate includes a linear polarizing plate and a retardation layer. Since the circularly polarizing plate can absorb the external light reflected in the image display device, it is possible to impart a function as an antireflection film to the optical laminate.

Polarizing plate, the easier to form an optical laminate having excellent impact resistance standpoint, it is preferable that toughness is 1 mJ / mm ³ or more, and still more preferably 2 mJ / mm ³ or more. The toughness of the polarizing plate may be, for example, 100 mJ / mm ³ or less, 50 mJ / mm ³ or less, or 10 mJ / mm ³ or less. The thickness of the polarizing plate is usually 5 μm or more, may be 20 μm or more, 25 μm or more, or 30 μm or more. The thickness of the polarizing plate is preferably 80 μm or less, and more preferably 60 μm or less.

≪Linear polarizing plate≫
The linear polarizing plate has a function of selectively transmitting unidirectional linearly polarized light composed of unpolarized light rays such as natural light. The linear polarizing plate contains a stretched film or stretched layer on which a dichroic dye is adsorbed, a cured product of a polymerizable liquid crystal compound, and a dichroic dye, and the dichroic dye is dispersed in the cured product of the polymerizable liquid crystal compound. , An oriented liquid crystal layer or the like can be provided as a polarizer layer. The dichroic dye refers to a dye having a property in which the absorbance in the major axis direction and the absorbance in the minor axis direction of the molecule are different. A linear polarizing plate using a liquid crystal layer as a polarizer layer is preferable because there is no limitation in the bending direction as compared with a stretched film or a stretched layer on which a dichroic dye is adsorbed.

(Stretched film on which a dichroic dye is adsorbed or a polarizer layer which is a stretched layer)
The polarizer layer, which is a stretched film on which a bicolor dye is adsorbed, is usually obtained by dyeing the polyvinyl alcohol-based resin film with a bicolor dye such as iodine in a step of uniaxially stretching the polyvinyl alcohol-based resin film. It can be produced through a step of adsorbing a bicolor dye, a step of treating a polyvinyl alcohol-based resin film on which the bicolor dye is adsorbed with an aqueous boric acid solution, and a step of washing with water after the treatment with the aqueous boric acid solution.

The thickness of the polarizer layer is usually 30 μm or less, preferably 18 μm or less, and more preferably 15 μm or less. Reducing the thickness of the polarizer layer is advantageous for thinning the polarizing plate 103. The thickness of the polarizer layer is usually 1 μm or more, and may be, for example, 5 μm or more.

The polyvinyl alcohol-based resin is obtained by saponifying the polyvinyl acetate-based resin. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, a copolymer of vinyl acetate and another monomer copolymerizable therewith is used. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acid compounds, olefin compounds, vinyl ether compounds, unsaturated sulfone compounds, and (meth) acrylamide compounds having an ammonium group. ..

The saponification degree of the polyvinyl alcohol-based resin is usually about 85 mol% or more and 100 mol% or less, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and polyvinyl formal, polyvinyl acetal, and the like modified with aldehydes can also be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1000 or more and 10000 or less, preferably 1500 or more and 5000 or less.

The polarizer layer, which is a stretched layer on which a dichroic dye is adsorbed, is usually a step of applying a coating liquid containing the above-mentioned polyvinyl alcohol-based resin on a base film, a step of uniaxially stretching the obtained laminated film, and uniaxial. A step of dyeing the polyvinyl alcohol-based resin layer of the stretched laminated film with a dichroic dye to adsorb the dichroic dye to form a polarizer layer, and boric acid on the film on which the dichroic dye is adsorbed. It can be produced through a step of treating with an aqueous solution and a step of washing with water after treatment with an aqueous boric acid solution. The base film used for forming the polarizer layer may be used as a protective layer for the polarizer layer. If necessary, the base film may be peeled off from the polarizer layer. The material and thickness of the base film may be the same as the material and thickness of the thermoplastic resin film described later.

The stretched film on which the dichroic dye is adsorbed or the polarizer layer which is a stretched layer may be used as it is as a linear polarizing plate, or a protective layer may be formed on one or both sides thereof and used as a linear polarizing plate. As the protective layer, a thermoplastic resin film described later can be used. The thickness of the obtained linear polarizing plate is preferably 2 μm or more and 40 μm or less.

The thermoplastic resin film is, for example, a cyclopolyolefin resin film; a cellulose acetate resin film made of a resin such as triacetyl cellulose or diacetyl cellulose; a polyester resin film made of a resin such as polyethylene terephthalate, polyethylene naphthalate, or polybutylene terephthalate; Examples of films known in the art such as polycarbonate-based resin films; (meth) acrylic-based resin films; polypropylene-based resin films and the like can be mentioned. The polarizer layer and the protective layer can be laminated via a bonding layer described later.

From the viewpoint of thinning, the thickness of the thermoplastic resin film is usually 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, still more preferably 40 μm or less, still more preferably 30 μm or less. Yes, it is usually 5 μm or more, preferably 10 μm or more.

A hard coat layer may be formed on the thermoplastic resin film. The hard coat layer may be formed on one side of the thermoplastic resin film, or may be formed on both sides. By providing the hard coat layer, a thermoplastic resin film having improved hardness and scratchability can be obtained. The hard coat layer can be formed in the same manner as the hard coat layer formed on the resin film described above.

(Polarizer layer, which is a liquid crystal layer)
The polymerizable liquid crystal compound used for forming the liquid crystal layer is a compound having a polymerizable reactive group and exhibiting liquid crystallinity. The polymerizable reactive group is a group involved in the polymerization reaction, and is preferably a photopolymerizable reactive group. The photopolymerizable reactive group refers to a group that can participate in the polymerization reaction by an active radical, an acid, or the like generated from the photopolymerization initiator. Examples of the photopolymerizable functional group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxylanyl group, an oxetanyl group and the like. Of these, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxylanyl group and an oxetanyl group are preferable, and an acryloyloxy group is more preferable. The type of the polymerizable liquid crystal compound is not particularly limited, and a rod-shaped liquid crystal compound, a disk-shaped liquid crystal compound, and a mixture thereof can be used. The liquid crystal property of the polymerizable liquid crystal compound may be a thermotropic liquid crystal or a lyotropic liquid crystal, and the phase-ordered structure may be a nematic liquid crystal or a smectic liquid crystal.

The dichroic dye used for the polarizer layer, which is a liquid crystal layer, preferably has an absorption maximum wavelength (λMAX) in the range of 300 to 700 nm. Examples of such a bicolor 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 preferable. The dichroic dye may be used alone or in combination of two or more, but it is preferable to combine three or more. In particular, it is more preferable to combine three or more kinds of azo compounds. A part of the dichroic dye may have a reactive group or may have a liquid crystallinity.

In the polarizing layer, which is a liquid crystal layer, for example, a composition for forming a polarizing layer containing a polymerizable liquid crystal compound and a dichroic dye is applied onto an alignment film formed on a base film, and the polymerizable liquid crystal compound is polymerized. It can be formed by curing it. A polarizer layer may be formed by applying a composition for forming a polarizer layer on a substrate film to form a coating film, and then stretching the coating film together with the substrate film. The base film used for forming the polarizer layer may be used as a protective layer for the polarizer layer. The material and thickness of the base film may be the same as the material and thickness of the thermoplastic resin film described above.

Examples of a composition for forming a polarizer layer containing a polymerizable liquid crystal compound and a dichroic dye, and a method for producing a polarizer layer using this composition are JP-A-2013-373353 and JP-A-2013-33249. , JP-A-2017-83843, etc. can be exemplified. In the composition for forming a polarizer layer, in addition to the polymerizable liquid crystal compound and the dichroic dye, additives such as a solvent, a polymerization initiator, a cross-linking agent, a leveling agent, an antioxidant, a plasticizer, and a sensitizer are further added. It may be included. Only one of these components may be used, or two or more of these components may be used in combination.

The polymerization initiator that may be contained in the composition for forming a polarizer layer is a compound that can initiate a polymerization reaction of a polymerizable liquid crystal compound, and is photopolymerized in that the polymerization reaction can be initiated under lower temperature conditions. Sex initiators are preferred. Specific examples thereof include photopolymerization initiators capable of generating active radicals or acids by the action of light, and among them, photopolymerization initiators that generate radicals by the action of light are preferable. The content of the polymerization initiator is preferably 1 part by mass or more and 10 parts by mass or less, and more preferably 3 parts by mass or more and 8 parts by mass or less, based on 100 parts by mass of the total amount of the polymerizable liquid crystal compound. Within this range, the reaction of the polymerizable group proceeds sufficiently, and the orientation state of the liquid crystal compound is likely to be stabilized.

The thickness of the polarizer layer, which is a liquid crystal layer, 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.

The polarizer layer, which is a liquid crystal layer, may be used as a linear polarizing plate without peeling and removing the base film, or may be used as a linear polarizing plate by peeling and removing the base film from the polarizer layer. The polarizing element layer, which is a liquid crystal layer, may be used as a linear polarizing plate by forming a protective layer on one side or both sides thereof. As the protective layer, the above-mentioned thermoplastic resin film can be used.

The polarizer layer, which is a liquid crystal layer, may have an overcoat layer on one side or both sides of the polarizer layer for the purpose of protecting the polarizer layer. The overcoat layer can be formed, for example, by applying a material (composition) for forming the overcoat layer on the polarizer layer. Examples of the material constituting the overcoat layer include a photocurable resin and a water-soluble polymer. As a material constituting the overcoat layer, a (meth) acrylic resin, a polyvinyl alcohol-based resin, or the like can be used.

(Phase difference layer)
The retardation layer included in the polarizing plate may be one layer or two or more layers. The retardation layer is preferably laminated on the surface of the polarizer layer opposite to the front plate side. The retardation layer may have an overcoat layer that protects the surface thereof, a base film that supports the retardation layer, and the like. The retardation layer includes a λ / 4 layer, and may further include at least one of a λ / 2 layer and a positive C layer. When the retardation layer includes 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 layer 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 layer 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 protective layer, 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. The retardation layer may have a bonding layer for bonding the λ / 4 layer, the λ / 2 layer, and the positive C layer.

When the polymerizable liquid crystal compound is cured to form a retardation layer, the retardation layer can be formed by applying a composition containing the polymerizable liquid crystal compound to a base film and curing it. An orientation layer may be formed between the base film and the coating layer. 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 the layer obtained by curing the polymerizable liquid crystal compound, the retardation layer may be incorporated into the optical laminate in the form of having an alignment layer and a base film. The retardation layer can be bonded to the linear polarizing plate via the bonding layer.

≪Touch sensor panel≫
The touch sensor panel can be a sensor capable of detecting the position touched by the front plate and can have a structure having a transparent conductive layer. The touch sensor panel can have a base material that supports the transparent conductive layer in addition to the transparent conductive layer. The detection method is not limited, and touch sensor panels such as a resistive film method, a capacitance method, an optical sensor method, an ultrasonic method, an electromagnetic induction coupling method, and a surface acoustic wave method are exemplified. Among them, the capacitance type touch sensor panel is preferably used in terms of low cost, fast reaction speed, and thin film formation. The touch sensor panel may include an adhesive layer, a separation layer, a protective layer, and the like between the transparent conductive layer and the base material that supports the transparent conductive layer. Examples of the adhesive layer include an adhesive layer and an adhesive layer. Examples of the base material that supports the transparent conductive layer include a base material in which the transparent conductive layer is vapor-deposited on one surface, and a base material in which the transparent conductive layer is transferred via the adhesive layer.

An example of a capacitance type touch sensor panel is composed of a base material, a transparent conductive layer for position detection provided on the surface of the base material, and a touch position detection circuit. In a display device provided with an optical laminate having a capacitance type touch sensor panel, when the surface of the front plate is touched, the transparent conductive layer is grounded through the capacitance of the human body at the touched point. NS. The touch position detection circuit detects the grounding of the transparent conductive layer, and the touched position is detected. By having a plurality of transparent conductive layers separated from each other, more detailed position detection becomes possible.

The transparent conductive layer may be a transparent conductive layer made of a metal oxide such as ITO, or may be a metal layer made of a metal such as aluminum, copper, silver, gold, or an alloy thereof.

The separation layer can be a layer formed on a substrate such as glass and for separating the transparent conductive layer formed on the separation layer from the substrate together with the separation layer. The separation layer is preferably an inorganic layer or an organic layer. Examples of the material forming the inorganic layer include silicon oxide. As the material for forming the organic material layer, for example, a (meth) acrylic resin composition, an epoxy resin composition, a polyimide resin composition, or the like can be used.

The protective layer can be provided in contact with the transparent conductive layer to protect the conductive layer. The protective layer contains at least one of an organic insulating film and an inorganic insulating film, and these films can be formed by a spin coating method, a sputtering method, a vapor deposition method, or the like.

The touch sensor panel 30 can be manufactured, for example, as follows. In the first method, the base material is first laminated on the glass substrate via the adhesive layer. A transparent conductive layer patterned by photolithography is formed on the substrate. By applying heat, the glass substrate and the base material are separated, and a touch sensor panel composed of the transparent conductive layer and the base material can be obtained.

In the second method, a separation layer is first formed on the glass substrate, and if necessary, a protective layer is formed on the separation layer. A transparent conductive layer patterned by photolithography is formed on the separation layer (or protective layer). A peelable protective film is laminated on the transparent conductive layer, and the transparent conductive layer to the separation layer are transferred to separate the glass substrate. By adhering the base material and the separation layer via the adhesive layer and peeling off the peelable protective film, a touch sensor panel having the transparent conductive layer, the separation layer, the adhesive layer, and the base material in this order can be obtained. ..

Resins such as triacetyl cellulose, polyethylene terephthalate, cycloolefin polymer, polyethylene naphthalate, polyolefin, polycycloolefin, polycarbonate, polyether sulfone, polyarylate, polyimide, polyamide, polystyrene, and polynorbornene are used as the base material of the touch sensor panel. Examples include film.
Polyethylene terephthalate is preferably used from the viewpoint of easily forming a base material layer having a desired toughness.

The touch sensor panel, the easily form an optical laminate having excellent impact resistance standpoint, it is preferable that toughness is 2 mJ / mm ³ or more, still more preferably 10 mJ / mm ³ or more, 50 mJ / mm Most preferably, it is ^{3 or more.} The toughness of the touch sensor panel is, for example, 200 mJ / mm ³ or less.

The touch sensor panel preferably has a thickness of 30 μm or more from the viewpoint of easily forming an optical laminate having excellent impact resistance. The thickness of the touch sensor panel is, for example, 100 μm or less.

≪Back plate≫
As the back plate, a plate-like body capable of transmitting light, a component used in a normal display device, or the like can be used.

The thickness of the back plate may be, for example, 5 μm or more and 2000 μm or less, preferably 10 μm or more and 1000 μm or less, and more preferably 15 μm or more and 500 μm or less.

The plate-like body used for the back plate may be composed of only one layer, may be composed of two or more layers, and an example of the plate state described in the front plate can be used.

Examples of the components used in a normal display device used for the back plate include the above-mentioned touch sensor panel and organic EL display element.

≪Protective plate≫
As the protective plate, a resin plate-like body capable of transmitting light, a component used in a normal display device, or the like can be used. The resin plate-like body may be composed of only one layer, may be composed of two or more layers, and an example of the resin plate-like body described in the front plate can be used. .. Examples of the resin constituting the protective plate include triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, polyester, polystyrene, polyamide, polyetherimide, and poly (). Meta) Acrylic, polyimide, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polyethersulfone, polymethylmetha Examples thereof include polymers such as acrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate and polyamideimide. These polymers can be used alone or in combination of two or more.

Protective plate from easily form an optical laminate having excellent impact resistance standpoint, it is preferable that toughness is 1 mJ / mm ³ or more, still more preferably 4 mJ / mm ³ or more, 50 mJ / mm ³ It may be the above. The toughness of the protective plate is, for example, 200 mJ / mm ³ or less, and ^{may be 100 mJ / mm 3} or less. The thickness of the protective plate may be, for example, 5 μm or more and 2000 μm or less, preferably 10 μm or more and 1000 μm or less, more preferably 15 μm or more and 500 μm or less, and further preferably 30 μm or more and 100 μm or less.

(Lated layer)
The optical member can include a laminating layer for joining the two layers. The bonding layer is a layer composed of a pressure-sensitive adhesive or an adhesive. When the bonding layer is an adhesive layer, its thickness is less than 10 μm. As the pressure-sensitive adhesive used as the material of the bonding layer, the pressure-sensitive adhesive composition described in the above-mentioned xth pressure-sensitive adhesive layer can be used.

The adhesive used as the material of the bonding layer can be formed by combining one or more of, for example, a water-based adhesive, an active energy ray-curable adhesive, and the like. 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 photopolymerizable monomers such as a photocurable epoxy monomer, a photocurable acrylic monomer, and a photocurable urethane monomer, and oligomers derived from these monomers. Examples of the photopolymerization initiator include compounds containing substances that generate active species such as neutral radicals, anion radicals, and cationic radicals by irradiating them with active energy rays such as ultraviolet rays.

The thickness of the bonded layer may be, for example, 1 μm or more, preferably 1 μm or more and less than 10 μm, more preferably 2 μm or more and less than 10 μm, and further preferably 2.5 μm or more and 5 μm or less.

The two opposing surfaces that are bonded via the bonding layer may be subjected to corona treatment, plasma treatment, flame treatment, etc. in advance, or may have a primer layer or the like.

[Manufacturing method of optical laminate]
The optical laminate can be manufactured by a method including a step of laminating the front plate and the optical member via the pressure-sensitive adhesive layer. The surface of the front plate and the surface of the optical member in contact with the pressure-sensitive adhesive layer is preferably subjected to a surface activation treatment such as a corona treatment for the purpose of adjusting the adhesive force. The conditions for corona treatment can be set as appropriate, and the conditions may differ between one surface of the bonded surface and the other surface.
When the bonded surface is a transparent conductive layer of the touch sensor panel, it is preferable not to perform the corona treatment.

<Display device>
The display device according to the present invention includes an optical laminate according to the present invention. The 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 electroluminescent display device. The display device including the optical laminate of the present invention can also be used as a flexible display having excellent impact resistance and capable of bending or winding.

In the display device, the optical laminate is arranged on the visible side of the display element of the display device with the front plate facing the outside (the side opposite to the display element side, that is, the visual recognition side). It is preferable that the display device can be bent with the front plate side inside. The display device may be bendable with the front plate side facing outward.

The 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.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

<Preliminary test>
Three test pieces (for example, test pieces 1-1, 1-2, 1-3 in Test 1) were prepared in each of Tests 1 to 5. Each test piece has the structure of the optical laminate 100 shown in FIG. 1, and is configured by using the members shown in Table 1 for the front plate 10 and the first to third

optical members

21, 22, 23. For the first to third pressure-sensitive adhesive layers 31, 32, 33 in each test piece, the pressure-sensitive adhesive layer (thickness 25 μm) prepared as follows was used. In test 1, the member of the front plate differs between the three test pieces, in test 2, the member of the first optical member differs between the three test pieces, and in test 3, the member of the second optical member differs between the three test pieces. Differently, in Test 4, the third optical member was different among the three test pieces, and in Test 5, the front plate and the first to third optical members were different among the three test pieces. Each test piece was subjected to an impact resistance test by a method described later to measure the dent depth. Table 1 shows the measurement results.

In Table 1, the members 1, 2, and 3 are the resin films shown in Table 2. In Table 2, the toughness and thickness of the members 1, 2 and 3 are values measured by the method described later.

[Preparation of adhesive layer]
A (meth) acrylic resin used as a pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer was prepared by the following procedure. 95 parts of 2-ethylhexyl acrylate, 2 parts of dodecyl acrylate, and 3 parts of 2-hydroxypropyl acrylate were charged in a 1 L reaction vessel provided with a cooling device capable of refluxing nitrogen gas and controlling the temperature. The internal temperature was maintained at 60 ° C. by parsing with nitrogen gas for 1 hour to remove oxygen in the reaction vessel. After mixing the compounds charged in the reaction vessel so as to be uniform, 0.5 part of 1-hydroxycyclohexylphenyl ketone as a photopolymerization initiator was added and stirred, and the mixture was irradiated with a UV lamp (10 mW). A (meth) acrylic resin was obtained. The weight average molecular weight Mw of the obtained (meth) acrylic resin was 610,000.

100 parts of the (meth) acrylic resin (solid content conversion value) obtained above and 0.3 part of 1-hydroxycyclohexylphenyl ketone (solid content conversion value) as a photopolymerization initiator are mixed to prepare a pressure-sensitive adhesive. Obtained.

The obtained pressure-sensitive adhesive is applied to the silicone release-treated surface of the first release film whose base material is a PET film so as to have a thickness of 25 μm, and the second release whose base material is a PET film is applied on this coating layer. A laminated body in which films were bonded was prepared. The laminated body is subjected to UV irradiation (integrated light intensity 400 mJ / cm ² , illuminance 1.8 mW / cm ² , UVV standard), and the first release film, the adhesive layer, and the second release film are laminated in this order. Was produced.

[Measurement of toughness]
The toughness of the optical member was measured as follows in accordance with JIS K7161. A rectangular small piece having a long side of 110 mm and a short side of 10 mm was cut out from the optical member to be measured using a super cutter. Next, the upper and lower grippers of the tensile tester [Autograph AG-Xplus tester manufactured by Shimadzu Corporation] sandwich both ends of the small piece in the long side direction so that the gap between the grippers is 5 cm, and the temperature is 23 ° C. In an environment of 55% relative humidity, the pieces were pulled in the long side direction at a tensile speed of 4 mm / min. The toughness was calculated as the integral value of the stress-strain curve from the initial stage to the fracture.

[Impact resistance test]
A rectangular piece of 150 mm long side x 70 mm short side is cut out from the optical laminate to be measured using a super cutter, and the surface of the piece opposite to the front plate side is acrylic via an adhesive layer. It was pasted on the board. Then, in an environment of 23 ° C. and 55% relative humidity, the evaluation pen is placed at a height of 10 cm from the outermost surface of the front plate of the small piece so that the pen tip is positioned and the pen tip faces downward. It was held and the evaluation pen was dropped from that position. As the evaluation pen, a pen having a weight of 5.6 g and a pen tip diameter of 0.75 mm was used. The dent depth was measured using an image taken with an interferometer microscope (ContourGT-K3D Optical Microscope, manufactured by Bruker) for the small pieces after the evaluation pen was dropped.

[Thickness measurement]
The thickness of the sample was measured using a contact-type film thickness measuring device (“MS-5C” manufactured by Nikon Corporation). However, the polarizer layer and the alignment film were measured using a laser microscope (“OLS3000” manufactured by Olympus Corporation).

[Discussion of preliminary test results]
From the evaluation results of the dent depth in Tests 1 to 5 shown in Table 1, the dent depth is obtained by using a different type (different toughness) of the optical member closer to the surface on which the pen collides in the impact resistance test. It was found that the greater the toughness of the optical member, the smaller the dent depth.

<Examples 1 to 5, Comparative Examples 1 and 2>
As the optical laminates of Examples 1 to 5 and Comparative Examples 1 and 2, the optical laminate 100 shown in FIG. 1 was produced. In each optical laminate, the front plate 10, the first optical member (protective plate) 21, the second optical member (polarizing plate) 22, and the third optical member (touch sensor panel) 23 are configured by using those described later. .. In each optical laminate, the same adhesive layer (thickness 25 μm) as that used in the preliminary test was used for the first to third

adhesive layers

31, 32, 33. For each optical laminate, the evaluation value A was calculated based on the formula (1a). Table 3 shows the calculated evaluation value A.

Each optical laminate is subjected to an impact resistance test by the method shown in the preliminary test section, and is hit based on the following evaluation criteria by visual inspection and observation with a microscope (Nikon, MM-40 / 2U, X10 magnification). The scar was evaluated. Table 3 shows the evaluation results.
A: No dents are observed by visual observation or microscopic observation.
B: No dents are observed by visual observation. A dent is observed by microscopic observation.
C: A dent is observed by visual observation.

[Front plate 10]
After coating the composition for the hard coat layer on the transparent resin film (base material 11), the solvent is dried and UV-cured to form the hard coat layer 12 on one side of the front plate (length 177 mm × width 105 mm). ) Was prepared.

The composition for the hard coat layer is 30 parts by weight of a multifunctional acrylate (MIWON Specialty Chemical (Korea), MIRAMER M340) and 50 parts by weight of a nanosilica sol (average particle size 12 nm, solid content 40%) dispersed in propylene glycol monomethyl ether. , 17 parts by weight of ethyl acetate, 2.7 parts by weight of photopolymerization initiator (Ciba, I184), 0.3 parts by weight of fluorine-based additive (Shinetsu Chemical Industry Co., Ltd., KY1203) are blended using a stirrer. , A composition for a hard coat layer was produced by filtering using a filter made of polypropylene (PP) material.
As the resin film (base material 11), any of the polyamide-imide resin films of Production Examples 1 to 7 shown in Table 3 below was used.

[Manufacturing Example 1]
52 g (162.38 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB) and N, N-dimethylacetamide adjusted to 500 ppm in a 1 L separable flask equipped with a stirring blade under a nitrogen atmosphere. 673.93 g of (DMAc) was added and TFMB was dissolved in DMAc with stirring at room temperature. Next, 28.90 g (65.05 mmol) of 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride (6FDA) was added to the flask, and the mixture was stirred at room temperature for 3 hours. Then, 19.81 g (97.57 mmol) of terephthaloyl chloride (TPC) was added to the flask, and the mixture was stirred at room temperature for 1 hour. Next, 7.49 g (94.65 mmol) of pyridine and 14.61 g (143.11 mmol) of acetic anhydride were added to the flask, and the mixture was stirred at room temperature for 30 minutes, heated to 70 ° C. using an oil bath, and further 5 The mixture was stirred for a time to obtain a reaction solution.

The obtained reaction solution was cooled to room temperature, poured into a large amount of methanol in the form of filaments, the precipitated precipitate was taken out, immersed in methanol for 6 hours, and then washed with methanol. Next, the precipitate was dried under reduced pressure at 100 ° C. to obtain a polyamide-imide resin. DMAc was added to the obtained polyamide-imide resin so as to have a concentration of 15% by mass to prepare a polyamide-imide varnish.

The obtained polyamide-imide varnish was applied onto a smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") using an applicator so that the thickness of the free-standing film was 55 μm, and the temperature was 30 ° C. It was dried for 1 minute and then at 140 ° C. for 15 minutes to obtain a free-standing film. The free-standing film was fixed to a gold frame and further dried in the atmosphere at 230 ° C. for 30 minutes to obtain a polyamide-imide film having a film thickness of 50 μm.

[Manufacturing Example 2]
A polyamide-imide film having a film thickness of 60 μm was obtained in the same manner as in Production Example 1 except that the self-standing film was coated so that the film thickness was 65 μm.

[Manufacturing Example 3]
52 g (162.38 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB) and N, N-dimethylacetamide adjusted to 100 ppm in a 1 L separable flask equipped with a stirring blade under a nitrogen atmosphere. 693.8 g of (DMAc) was added, and TFMB was dissolved in DMAc with stirring at room temperature. Next, in a flask, 28.90 g (65.05 mmol) of 4,4'-(hexafluoroisopropyridene) diphthalic acid dianhydride (6FDA) and 3,3', 4,4'-biphenyltetracarboxylic dianhydride 9.57 g (32.52 mmol) of (BPDA) was added, and the mixture was stirred at room temperature for 3 hours. Then, 13.21 g (63.10 mmol) of terephthaloyl chloride (TPC) was added to the flask, and the mixture was stirred at room temperature for 1 hour. Next, 4.99 g (63.10 mmol) of pyridine and 21.91 g (214.66 mmol) of acetic anhydride were added to the flask, and the mixture was stirred at room temperature for 30 minutes, heated to 70 ° C. using an oil bath, and further 1 The mixture was stirred for a time to obtain a reaction solution.

The obtained polyamide-imide varnish was applied onto a smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") using an applicator so that the thickness of the free-standing film was 55 μm, and the temperature was 30 ° C. It was dried for 1 minute and then at 140 ° C. for 15 minutes to obtain a free-standing film. The free-standing film was fixed to a gold frame and further dried in the atmosphere at 300 ° C. for 30 minutes to obtain a polyamide-imide film having a film thickness of 50 μm.

[Manufacturing Example 4]
A polyamide-imide film having a film thickness of 60 μm was obtained in the same manner as in Production Example 3 except that the self-standing film was coated so that the film thickness was 65 μm.

[Manufacturing Example 5]
A polyamide-imide film having a film thickness of 40 μm was obtained in the same manner as in Production Example 3 except that the self-standing film was coated so that the film thickness was 45 μm.

[Manufacturing Example 6]
In a nitrogen gas atmosphere, 14.67 g (45.8 mmol) of 2,2'-bis (trifluoromethyl) benzidine (TFMB) and a water content of 200 ppm were prepared in a 1 L separable flask equipped with a stirring blade. -233.3 g of dimethylacetamide (DMAc) was added, and TFMB was dissolved in DMAc with stirring at room temperature. Next, 4.283 g (13.8 mmol) of 4,4'-oxydiphthalic dianhydride (OPDA) was added to the flask, and the mixture was stirred at room temperature for 16.5 hours. Then, 1.359 g (4.61 mmol) of 4,4'-oxybis (benzoyl chloride) (OBBC) and 5.609 g (27.6 mmol) of terephthaloyl chloride (TPC) were added to the flask, and the mixture was stirred at room temperature for 1 hour. .. Next, 4.937 g (48.35 mmol) of acetic anhydride and 1.501 g (16.12 mmol) of 4-picoline were added to the flask, and the mixture was stirred at room temperature for 30 minutes, heated to 70 ° C. using an oil bath, and further. The mixture was stirred for 3 hours to obtain a reaction solution. After cooling the obtained reaction solution to room temperature, 360 g of methanol and 170 g of ion-exchanged water were added to obtain a precipitate of polyamide-imide. It was immersed in methanol for 12 hours, collected by filtration and washed with methanol. Next, the precipitate was dried under reduced pressure at 100 ° C. to obtain a polyamide-imide resin. DMAc was added to the obtained polyamide-imide resin so as to have a concentration of 15% by mass to prepare a polyamide-imide varnish. The obtained polyamide-imide varnish was applied onto a smooth surface of a polyester base material (manufactured by Toyobo Co., Ltd., trade name "A4100") using an applicator so that the thickness of the free-standing film was 55 μm, and the temperature was 30 ° C. It was dried for 1 minute and then at 140 ° C. for 15 minutes to obtain a free-standing film. The free-standing film was fixed to a gold frame and further dried in the atmosphere at 300 ° C. for 30 minutes to obtain a polyamide-imide film having a film thickness of 50 μm.

[Manufacturing Example 7]
A polyamide-imide film having a film thickness of 60 μm was obtained in the same manner as in Production Example 6 except that the self-standing film was coated so that the film thickness was 65 μm.

The thickness of the hard coat layer 12 was as shown in Table 3.
The toughness T ₀ of the front plate 10 was measured by the method shown in the preliminary test section. Table 3 shows the measurement results. The toughness T ₀ of the front plate 10 has a different value depending on the type of the base material 11 and the thickness of the hard coat layer 12.

[Protective plate 21 (first optical member)]
As the protective plate 21, any of the following resin films shown in Table 3 was used.
-PET80 (trade name: SH82, manufactured by SKC, polyethylene terephthalate film, thickness 80 μm)
-TAC60 (trade name: KC6UAW, Konica Minolta Co., Ltd., triacetyl cellulose film, thickness 60 μm)
-TAC40 (trade name: KC4UAW, Konica Minolta Co., Ltd., triacetyl cellulose film, thickness 40 μm)
-COP13 (trade name: ZF14-013, Zeon Corporation, cycloolefin resin film, thickness 13 μm)
It was measured by the method shown toughness T ₁ of the protection plate 21 in the section of the preliminary tests. Table 3 shows the measurement results. The toughness T ₁ of the protective plate 21 had a different value depending on the type of the resin film.

[Polarizing plate 22 (second optical member)]
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 a mass ratio of iodine / potassium iodide / water 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 polarizer 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 polarizer was 7 μm.

The polarizer obtained above and the base material were bonded to each other with a nip roll via an aqueous adhesive. 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 base film on one side. The water-based adhesive is 100 parts of water, 3 parts of carboxyl group-modified polyvinyl alcohol ("Kuraray Poval KL318", manufactured by Kuraray Co., Ltd.) and water-soluble polyamide epoxy resin ("Smiley's resin 650" (solid content concentration 30%). (Aqueous solution) and 1.5 parts (manufactured by Taoka Chemical Industry Co., Ltd.) were added to prepare.
A retardation film (thickness 5 μm, layer structure: a layer obtained by curing the liquid crystal compound and an alignment film) containing a layer obtained by polymerizing and curing the liquid crystal compound on the polarizing element via an adhesive layer having a thickness of 5 μm. A λ / 2 plate (thickness 2 μm) / an adhesive layer (thickness 2 μm) / a λ / 4 plate (thickness 1 μm) composed of a layer in which a liquid crystal compound was cured and an alignment film) was bonded. In this way, a polarizing plate having a layer structure of "base material / polarizer (thickness 7 μm) / pressure-sensitive adhesive layer (thickness 5 μm) / retardation film (thickness 5 μm)" was produced.

As shown in Table 3, the resin film described in any of the following was used as the base material to be bonded to the polarizer.
-TAC25 (trade name: KC2UAW, Konica Minolta Co., Ltd., triacetyl cellulose film, thickness 25 μm)
-COP23 (trade name: ZF14-023, Zeon Corporation, cycloolefin resin film, thickness 23 μm)
The toughness T _{2 of the} polarizing plate 22 was measured by the method shown in the preliminary test section. Table 3 shows the measurement results. The toughness T _{2 of the} polarizing plate 22 had a different value depending on the type of the base material.

[Touch sensor panel 23 (third optical member)]
A touch sensor panel having a length of 177 mm and a width of 105 mm was prepared in which a transparent conductive layer, a separation layer, an adhesive layer, and a base material were laminated in this order. The transparent conductive layer contained an ITO layer, and the separation layer contained a cured layer of an acrylic resin composition, and the total thickness of both was 7 μm. The adhesive layer had a thickness of 2 μm.
As the base material, the resin film described in any of the following shown in Table 3 was used.
-PET80 (trade name: SH82, manufactured by SKC, polyethylene terephthalate film, thickness 80 μm)
-TAC25 (trade name: KC2UAW, Konica Minolta Co., Ltd., triacetyl cellulose film, thickness 25 μm)
-COP23 (trade name: ZF14-023, Zeon Corporation, cycloolefin resin film, thickness 23 μm)
It was measured by the method shown toughness T ₃ of the touch sensor panel 23 in the section of the preliminary tests. Table 3 shows the measurement results. _{The toughness T 3} of the touch sensor panel 23 had a different value depending on the type of the base material.

10 front plate, 11 base material, 12 hard coat layer, 21 first optical member (protective plate), 22 second optical member (polarizing plate), 23 third optical member (touch sensor panel), 31 first adhesive layer , 32 second pressure-sensitive adhesive layer, 33 third pressure-sensitive adhesive layer.

Claims

An optical laminate in which a front plate including a base material and n (n is an integer of 2 or more) optical members are laminated in this order.
Adhesive layers having a thickness of 10 μm or more are in contact with each other and laminated on the surface of the n optical members on the front plate side.
Assuming that the xth optical member (x is an integer of 1 or more and n or less) from the side closer to the front plate is the xth optical member, the evaluation value A calculated by the following formula (1) is the following formula (2):
50 ≤ A ≤ 500 (2)
An optical laminate that satisfies the relationship.

[In the formula (1), T 0 [mJ / mm 3 ] is the toughness of the front plate, and a 0 is (thickness of the base material [μm]) / (thickness of the front plate [μm]). , T x [mJ / mm 3 ] is the toughness of the xth optical member, and a x is (from the surface of the front plate opposite to the optical member side to the front plate side of the x optical member. Distance to the surface [μm]) / (thickness of the xth optical member [μm]). ]
The optical laminate according to claim 1, wherein one of the n optical members is a polarizing plate.
The optical laminate according to claim 1 or 2, wherein one of the n optical members is a touch sensor panel.
The optical laminate according to any one of claims 1 to 3, wherein n is an integer of 4 or less.
A display device including the optical laminate according to any one of claims 1 to 4.