WO2021024639A1

WO2021024639A1 - Laminate

Info

Publication number: WO2021024639A1
Application number: PCT/JP2020/024985
Authority: WO
Inventors: 昇祐李; 正熙金
Original assignee: 住友化学株式会社
Priority date: 2019-08-05
Filing date: 2020-06-25
Publication date: 2021-02-11
Also published as: KR20220040455A; TW202106839A; CN114174874A; JP2021026109A

Abstract

The purpose of the present invention is to provide a laminate having improved bending durability under a moist and hot environment. A laminate according to the present invention includes: a front plate; a circular polarizing plate; and a pressure sensitive adhesive layer interposed between the front plate and the circular polarizing plate, wherein the relationship of 0.6≤B/A≤2 is satisfied, where A (µm) denotes the thickness of the laminate, and B(%) denotes the compression restoration rate of the laminate, and B(%) is the proportion (%), with respect to the largest depth of a recess formed by pressing the spherical indentor having a diameter of 0.4 mm from the surface of the front plate side of the laminate toward the inside of the laminate by a force of 100 mN for 60 seconds, of the depth of the recess to be restored when a spherical indentor is removed from the laminate.

Description

Laminate

The present invention relates to a laminate.

A display device including a pressure-sensitive adhesive film composed of a pressure-sensitive adhesive composition and a laminate containing a pressure-sensitive adhesive layer formed by using this type of pressure-sensitive adhesive film is known (Patent Documents 1 and 2).

Korean Patent No. 10-2017-093610 Korean Patent No. 10-2016-0053788

The pressure-sensitive adhesive layer formed by using the above-mentioned pressure-sensitive adhesive film generally has a property rich in flexibility, and thus has excellent stress relaxation performance for relaxing external stress. On the other hand, when the laminate to which the adhesive layer is applied is bent in a moist heat environment, cracks such as cracks and cracks tend to occur in the laminate, or bubbles tend to be generated in the adhesive layer. It has been pointed out that it lacks bending durability. Therefore, the development of a laminated body having improved bending durability in a moist heat environment is eagerly desired.

In view of the above circumstances, an object of the present invention is to provide a laminated body having improved bending durability in a moist heat environment.

The present invention provides the following laminates.
[1] A laminate including a front plate, a circular polarizing plate, and an adhesive layer interposed between the front plate and the circular polarizing plate.
When the thickness of the laminated body is A (μm) and the compression recovery rate of the laminated body is B (%), the laminated body satisfies the relationship of 0.6 ≦ B / A ≦ 2.
The B (%) is the maximum of the dent formed by pushing a spherical indenter having a diameter of 0.4 mm from the surface of the laminated body on the front plate side toward the inside of the laminated body with a force of 100 mN for 60 seconds. A laminate that is the ratio (%) of the depth of the recess that recovers when the spherical indenter is removed from the laminate to the depth.
[2] The laminate according to [1], wherein the A (μm) is 150 μm or less.
[3] The laminate according to [1] or [2], wherein the circularly polarizing plate includes either a film formed from a liquid crystal layer or a polyvinyl alcohol-based resin film.
[4] The front plate is either a resin film or a resin film with a hard coat layer having a hard coat layer on at least one surface of the resin film, according to any one of [1] to [3]. The laminate described.
[5] A display device including the laminate according to any one of [1] to [4].
[6] The display device further includes a back plate.
The display device according to [5], wherein the back plate is laminated on the circular polarizing plate side of the laminated body.
[7] The display device according to [6], wherein the back plate is a touch sensor panel.
[8] The display device according to any one of [5] to [7], which can be bent with the front plate side inside.

According to the present invention, it is possible to provide a laminated body having improved bending durability in a moist heat environment.

It is the schematic sectional drawing which shows an example of the laminated body which concerns on this invention. It is explanatory drawing explaining the method of obtaining the compression restoration ratio (B (%)) of the laminated body which concerns on this invention.

Hereinafter, a laminate according to one aspect of the present invention (hereinafter, also simply referred to as “laminate”) will be described with reference to the drawings.

[Laminate]
FIG. 1 shows a schematic cross-sectional view of a laminated body according to one aspect of the present invention. In FIG. 1, the laminate 100 includes a front plate 10, a circular polarizing plate 30, and an adhesive layer 20 interposed between the front plate 10 and the circular polarizing plate 30. The front plate may be either a resin film described later or a resin film with a hard coat layer having a hard coat layer on one surface of the resin film. In the laminate 100 of FIG. 1, the resin film 12 with the hard coat layer 11 is used as the front plate 10. Further, in the laminated body 100, the pressure-sensitive adhesive layer 20 can be formed by using a pressure-sensitive adhesive composition as described later. The circular polarizing plate 30 can include a linear polarizing plate and a retardation layer as described later. Unless otherwise specified, the term "laminated body" in the present specification will be described assuming that it is applied to a display device described later. In this case, the front plate is located on the side (visual side) close to the surface of the laminate applied to the display device. The circular polarizing plate is located on the side far from the surface of the laminate applied to the display device.

The thickness of the laminated body 100 is not particularly limited because it varies depending on the function required for the laminated body, the application of the laminated body, and the like, but it is preferably 150 μm or less. That is, the laminated body 100 preferably has A (μm) of 150 μm or less. The thickness of the laminate 100 is, for example, 50 μm or more and 200 μm or less, preferably 75 μm or more and 150 μm or less, and more preferably 100 μm or more and 130 μm or less.

The plan view shape of the laminated body 100 may be, for example, a rectangular shape, preferably a rectangular shape having a long side and a short side, and more preferably a rectangular shape. When the shape of the 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 may be, 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 laminate may have corners R-processed, end portions notched, or perforated.

The laminated body 100 can be applied to, for example, a display device or the like. That is, the display device according to one aspect of the present invention preferably includes the laminated body 100. 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 display device may have a touch panel function. Further, the display device to which the laminated body 100 is applied can be used as a flexible display that can be bent or wound. The display device may be able to be bent with the front plate 10 side on the outside, but it is preferable that the display device can be bent with the front plate 10 side on the inside. Further, it is also preferable that the display device can be bent with the front plate 10 side on the inside and the front plate 10 side on the outside.

[Relationship between stack thickness and compression recovery rate]
The laminated body 100 satisfies the relationship of 0.6 ≦ B / A ≦ 2 when the thickness of the laminated body 100 is A (μm) and the compression restoration rate of the laminated body 100 is B (%). The above B (compression restoration rate of the laminated body 100, the unit is%) is a spherical indenter having a diameter of 0.4 mm directed from the surface of the laminated body 100 on the front plate 10 side toward the inside of the laminated body 100 with a force of 100 mN for 60 seconds. It is the ratio (%) of the depth of the dent that recovers when the spherical indenter is removed from the laminate with respect to the maximum depth of the dent formed by pushing. Specifically, the above B (%) is a numerical value obtained based on the calculation described below, as will be understood by referring to FIG. That is, as shown in FIG. 2, first, in the laminated body, a spherical indenter Z having a diameter of 0.4 mm is pushed toward the inside of the laminated body from the surface on the front plate side of the laminated body with a force of 100 mN for 60 seconds to make a dent ( A recess) is formed, and the "maximum depth x" of this recess is obtained. Next, 60 seconds after the spherical indenter Z is removed from the laminated body, the "recovery recess depth y" in the recess is determined. Finally, the above B (%) can be obtained by calculating "the depth y of the dent to be recovered" / "maximum depth x" x 100.

When the laminated body 100 satisfies the relationship of 0.6 ≦ B / A ≦ 2, cracks such as cracks and cracks are suppressed from being generated in the laminated body 100 even when the laminated body 100 is bent in a moist heat environment. It is also possible to suppress the generation of air bubbles in the pressure-sensitive adhesive layer 20. Therefore, it is possible to provide the laminated body 100 having improved bending durability in a moist heat environment. Specifically, as shown in Examples described later, the laminate 100 has a diameter (φ) of 20 mm on the surface on the front plate 10 side after being left for 24 hours in a moist heat environment of 60 ° C./90% RH. Even when the mandrel, which is the following cylindrical jig, is arranged and the laminate 100 is bent along the mandrel, at least cracks such as cracks and cracks are suppressed in the front plate 10, or an adhesive is used. The generation of air bubbles in the layer 20 can be suppressed (hereinafter, such performance is also referred to as excellent in "wet heat bending durability").

Further, as shown in Examples described later, when a load of 100 g is applied to the surface of the laminated body 100 on the front plate 10 side using a pencil having a core hardness of 6B, the laminated body 100 is described above. The concave marks formed on the surface can be eliminated in less than 90 minutes (hereinafter, such performance is also referred to as "excellent in" surface hardness ").

The laminated body 100 preferably satisfies the relationship of 0.7 ≦ B / A ≦ 1.5, and more preferably 0.8 ≦ B / A ≦ 1. Further, in the laminated body 100, the B is preferably 95% or more, more preferably 98% or more, still more preferably 99% or more. The above B is most preferably 100%, but may be less than 100%. In these cases, even when the laminated body 100 is bent in a moist heat environment, it is sufficient that cracks such as cracks and cracks are generated in the laminated body 100 or bubbles are generated in the adhesive layer 20. Can be suppressed.

On the other hand, when the B / A value of the laminated body 100 is less than 0.6, cracks such as cracks and cracks or bubbles of the adhesive layer 20 are generated in the laminated body 100 when bent in a moist heat environment. There is a risk that it cannot be sufficiently suppressed. If the B / A value of the laminated body 100 exceeds 2, the strength of the laminated body 100 may not be sufficient.

In the present specification, "bending" includes a form of bending in which a curved surface is formed in a bent portion. In the form of bending, the radius of curvature of the bent inner surface is not limited unless otherwise specified. Further, "bending" includes a form of refraction in which the refraction angle of the inner surface is larger than 0 degrees and less than 180 degrees unless otherwise specified, and the radius of curvature of the inner surface is close to zero, or the refraction angle of the inner surface is 0 degrees. Includes certain forms of folding. Hereinafter, specific aspects of the laminated body will be described in more detail.

[Front plate]
The laminate 100 includes a front plate 10. When the front plate 10 is applied to the display device as described above, the front plate 10 is located on the side (visual side) close to the surface of the laminated body 100. The material and thickness of the front plate 10 are not limited as long as it is a plate-like body capable of transmitting light, and the front plate 10 may be composed of only one layer or may be composed of two or more layers. Examples of the front plate 10 include a resin plate-like body (for example, a resin plate, a resin sheet, a resin film, etc.), a glass plate-like body (for example, a glass plate, a glass film, etc.), and a resin plate-like body. Examples thereof include a laminate with a glass plate-like body. The front plate 10 can form the outermost surface of the display device.

The thickness of the front plate 10 may be, for example, 30 μm or more and less than 60 μm, preferably 40 μm or more and 55 μm or less, and more preferably 45 μm or more and 50 μm or less. In the present invention, the thickness of each layer can be measured according to the thickness measuring method described in Examples described later.

When the front plate 10 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 such as a resin film include triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, polyester, and polystyrene. Polyamide, polyetherimide, poly (meth) acrylic, polyimide, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone , 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, a resin film formed of a polymer such as polyimide, polyamide, or polyamideimide is preferable.

The front plate 10 is preferably either a resin film or a resin film having a hard coat layer having a hard coat layer on at least one surface of the resin film from the viewpoint of increasing hardness. As the resin film, a film produced from the above-mentioned resin can be used. The hard coat layer may be formed on one surface of the resin film, or may be formed on both surfaces. By providing the hard coat layer, a resin film having improved hardness and scratch resistance can be obtained. 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 hardness. Additives are not limited, and include inorganic fine particles, organic fine particles, or mixtures thereof.

When the laminate 100 is used in a display device, the front plate 10 not only has a function of protecting the front surface (screen) of the display device (function as a window film), but also has a function as a touch sensor and a blue light cut function. , It may have a viewing angle adjustment function and the like.

[Adhesive layer]
The laminate 100 includes an adhesive layer 20. The pressure-sensitive adhesive layer 20 is interposed between the front plate 10 and the circular polarizing plate 30 described later. The pressure-sensitive adhesive layer 20 may be, for example, a layer composed of a pressure-sensitive adhesive or an adhesive, or a layer obtained by subjecting the layer to some treatment. As used herein, the term "adhesive" is also referred to as a pressure-sensitive adhesive. Examples of the pressure-sensitive adhesive include (meth) acrylic pressure-sensitive adhesive, styrene-based pressure-sensitive adhesive, silicone-based pressure-sensitive adhesive, rubber-based pressure-sensitive adhesive, urethane-based pressure-sensitive adhesive, polyester-based pressure-sensitive adhesive, epoxy-based copolymer pressure-sensitive adhesive, and the like. .. The pressure-sensitive adhesive layer 20 may be composed of one layer, may be composed of two layers, or may be composed of three or more layers. When the pressure-sensitive adhesive layer 20 is composed of two or more layers, the composition of each layer may be the same or different.

The gel fraction of the pressure-sensitive adhesive layer 20 is preferably 10 to 98% by mass, more preferably 25 to 98% by mass, and even more preferably 45 to 90% by mass. When the gel fraction is within the above range, both durability and adhesive strength can be achieved at the same time. The gel fraction can be measured by the method described in Examples below.

Here, in the present invention, by applying a predetermined pressure-sensitive adhesive layer to the laminated body, the laminated body can satisfy the above-mentioned relationship of 0.6 ≦ B / A ≦ 2. The material of such a pressure-sensitive adhesive layer can be obtained by preparing a predetermined pressure-sensitive adhesive composition. As a method of preparing a predetermined pressure-sensitive adhesive composition, for example, a predetermined pressure-sensitive adhesive composition may be formed from the pressure-sensitive adhesive composition A described later, or a (meth) acrylic polymer A described later may be used in the pressure-sensitive adhesive composition A. Examples thereof include a method of changing the type of the constituent monomers and adjusting the molecular weight of the (meth) acrylic polymer A. The predetermined pressure-sensitive adhesive composition used as the material of the pressure-sensitive adhesive layer is the pressure-sensitive adhesive composition A as long as the laminated body satisfies the relationship of 0.6 ≦ B / A ≦ 2 when this is applied to the laminated body. Adhesive composition constituting (meth) acrylic adhesive, styrene adhesive, silicone adhesive, rubber adhesive, urethane adhesive, polyester adhesive, epoxy copolymer adhesive, etc. It may be a thing. Hereinafter, the pressure-sensitive adhesive composition A will be specifically described.

<Adhesive composition A>
The pressure-sensitive adhesive layer can be formed from a pressure-sensitive adhesive composition containing a (meth) acrylic polymer (hereinafter, also referred to as “pressure-sensitive adhesive composition A”). The pressure-sensitive adhesive composition A may be an active energy ray-curable type or a thermosetting type. As used herein, the term "(meth) acrylic polymer" refers to at least one selected from the group consisting of acrylic polymers and methacrylic polymers. The same applies to other terms with "(meta)". When the pressure-sensitive adhesive composition A contains a plurality of (meth) acrylic polymers, the (meth) acrylic polymers may be the same or different. Hereinafter, the (meth) acrylic polymer contained in the pressure-sensitive adhesive composition A is also referred to as “(meth) acrylic polymer A”.

(Active energy ray-curable pressure-sensitive adhesive composition)
When the pressure-sensitive adhesive composition A is an active energy ray-curable pressure-sensitive adhesive composition, the (meth) acrylic polymer A contained in the pressure-sensitive adhesive composition A has a structural unit derived from a monomer having a reactive functional group. Preferably, it is 1% by mass or less based on the total mass of the polymer. Examples of the reactive functional group include a hydroxyl group, a carboxyl group, an amino group, an amide group, an epoxy group and the like. As a result, the flexibility of the pressure-sensitive adhesive layer is improved, and when it is bent in a moist heat environment, it tends to be easy to suppress the generation of cracks such as cracks and cracks in the laminate or bubbles in the pressure-sensitive adhesive layer. In the (meth) acrylic polymer A, the structural unit derived from the monomer having a reactive functional group is more preferably based on the total mass of the polymer from the viewpoint of suppressing the generation of cracks or bubbles in the pressure-sensitive adhesive layer during bending. Is 0.01% by mass or less, more preferably has no structural unit derived from a monomer having a reactive functional group, and even more preferably has a hydroxyl group, a carboxyl group, an amino group, an amide group, and an epoxy group. do not do.

The (meth) acrylic polymer A can contain a structural unit derived from a (meth) acrylic monomer having a linear or branched chain-like alkyl group having 1 to 24 carbon atoms. The (meth) acrylic monomer having an alkyl group having 1 or more and 24 or less carbon atoms in a linear or branched chain may be, for example, a (meth) acrylic acid alkyl ester, and an example thereof is (meth). ) Butyl acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, isooctyl (meth) acrylate, (meth) Examples thereof include isodecyl acrylate, 2-ethylhexyl (meth) acrylate, and isobornyl (meth) acrylate. The (meth) acrylic polymer A may be a polymer or a copolymer containing one or more of the above (meth) acrylic acid alkyl esters as monomers. The content of the (meth) acrylic polymer A in the pressure-sensitive adhesive composition A may be, for example, 50% by mass or more and 100% by mass or less, preferably 80% by mass or less, based on 100 parts by mass of the solid content of the pressure-sensitive adhesive composition A. It is by mass% or more and 99.5% by mass or less, and more preferably 90% by mass or more and 99% by mass or less.

The weight average molecular weight (Mw) of the (meth) acrylic polymer A may be, for example, 100,000 or more and 2 million or less, and is preferably 500,000 or more and 150 or more from the viewpoint of suppressing cracks at the time of bending, suppressing bubbles in the pressure-sensitive adhesive layer, and the like. It is less than 10,000. The weight average molecular weight in the present specification can be determined based on a standard polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method, as described in the column of Examples described later.

The pressure-sensitive adhesive composition A may contain one or more (meth) acrylic polymers A. Further, the pressure-sensitive adhesive composition A may contain only the (meth) acrylic polymer A as a constituent component thereof, or 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 or polyols that form an ester bond with a carboxyl group; polyisocyanate compounds that form an amide bond with a carboxyl group, and the like. Of these, polyisocyanate compounds are preferable. When the pressure-sensitive adhesive composition A contains a cross-linking agent, the content of the cross-linking agent may be, for example, 5 parts by mass or less, preferably 3 parts by mass or less, based on 100 parts by mass of the (meth) acrylic polymer A. It is preferably 1 part by mass or less, more preferably 0.5 part by mass or less. The pressure-sensitive adhesive composition A may not contain a cross-linking agent.

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 or electron beams, and has adhesiveness even before irradiation with active energy rays. It is an adhesive composition having a property that it can be brought into close contact with an adherend such as, and can be cured by irradiation with active energy rays to adjust the adhesive force and the like. The active energy ray-curable pressure-sensitive adhesive composition is preferably an ultraviolet-curable type.

When the pressure-sensitive adhesive composition A is an active energy ray-curable pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition A can further contain an active energy ray-polymerizable compound, a photopolymerization initiator, a photosensitizer, and the like. ..

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 in the molecule. Examples thereof include (meth) acrylic compounds such as (meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers having two (meth) acryloyloxy groups. The pressure-sensitive adhesive composition A can contain an active energy ray-polymerizable compound in an amount of 0.1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the solid content of the pressure-sensitive adhesive composition A.

Examples of the photopolymerization initiator include benzophenone, benzyl dimethyl ketal, 1-hydroxycyclohexyl ketone and the like. When the pressure-sensitive adhesive composition A contains a photopolymerization initiator, it can contain one kind or two or more kinds. When the pressure-sensitive adhesive composition A contains a photopolymerization initiator, the total content thereof may be, for example, 0.01 part by mass or more and 1.0 part by mass or less with respect to 100 parts by mass of the solid content of the pressure-sensitive adhesive composition A. ..

The pressure-sensitive adhesive composition A contains fine particles, beads (resin beads, glass beads, etc.), glass fibers, resins other than the base polymer, a pressure-sensitive adhesive, and a filler (metal powder or other inorganic substances) for imparting light scattering properties. Additives such as powders), antioxidants, UV absorbers, dyes, pigments, colorants, antifoaming agents, corrosion inhibitors and the like can be included. The pressure-sensitive adhesive composition A preferably does not contain an organic solvent from the viewpoint of preventing the problem of deterioration of durability due to the residual solvent.

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

(Thermosetting adhesive composition)
When the pressure-sensitive adhesive composition A is a thermosetting pressure-sensitive adhesive composition, the (meth) acrylic polymer A is a (meth) acrylic having an alkyl group having 2 to 20 carbon atoms as a monomer unit constituting the polymer. It is preferable to contain an acid alkyl ester and a monomer having a reactive functional group in the molecule (reactive functional group-containing monomer). When the pressure-sensitive adhesive composition A is a thermosetting pressure-sensitive adhesive composition, it preferably further contains a heat-crosslinking agent.

The (meth) acrylic polymer A can exhibit preferable tackiness by containing a (meth) acrylic acid alkyl ester having an alkyl group having 2 to 20 carbon atoms as a monomer unit constituting the polymer. it can. The (meth) acrylic acid alkyl ester having an alkyl group having 2 to 20 carbon atoms is, for example, a homopolymer having a glass transition temperature (Tg) of −40 ° C. or lower (hereinafter, may be referred to as “low Tg alkyl acrylate”). It is preferable to include it. By containing the low Tg alkyl acrylate as a constituent monomer unit, the flexibility of the pressure-sensitive adhesive layer is improved, and cracks at the time of bending or generation of bubbles in the pressure-sensitive adhesive layer can be more easily suppressed. The glass transition temperature (Tg) of the (meth) acrylic polymer A can be determined by using a conventionally known method such as differential thermal analysis (DTA).

Examples of the low Tg alkyl acrylate include n-butyl acrylate (Tg-54 ° C.), n-octyl acrylate (Tg-65 ° C.), isooctyl acrylate (Tg-58 ° C.), and 2-ethylhexyl acrylate (Tg). -70 ° C), isononyl acrylate (Tg-58 ° C), isodecyl acrylate (Tg-60 ° C), isodecyl methacrylate (Tg-41 ° C), n-lauryl methacrylate (Tg-65 ° C), tridecyl acrylate (Tg-55 ° C.), tridecyl methacrylate (-40 ° C.) and the like are preferably mentioned. Among them, as the low Tg alkyl acrylate, the Tg of the homopolymer is more preferably −45 ° C. or lower, and particularly preferably −50 ° C. or lower. Specifically, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferable. These may be used alone or in combination of two or more.

The (meth) acrylic polymer A preferably contains low Tg alkyl acrylate as a lower limit value of 85% by mass or more, more preferably 90% by mass or more, as a monomer unit constituting the polymer. It is more preferable to contain it in an amount of mass% or more.

Further, the (meth) acrylic polymer A preferably contains the above-mentioned low Tg alkyl acrylate as a monomer unit constituting the polymer in an upper limit of 99.9% by mass or less, and preferably 99.5% by mass or less. Is more preferable, and it is further preferable that the content is 99% by mass or less. By containing 99.9% by mass or less of the low Tg alkyl acrylate, a suitable amount of other monomer components (particularly reactive functional group-containing monomer) can be introduced into the (meth) acrylic polymer A.

The (meth) acrylic polymer A is a monomer having a glass transition temperature (Tg) of more than 0 ° C. as a homopolymer (hereinafter, may be referred to as “hard monomer”) from the viewpoint of further exerting the effect of the present invention. It is preferable to reduce the content as much as possible. Specifically, the (meth) acrylic polymer A preferably has a hard monomer content of 15% by mass or less as an upper limit as a monomer unit constituting the polymer, and is preferably 10% by mass or less. More preferably, it is more preferably 5% by mass or less. This hard monomer also includes a reactive functional group-containing monomer described later.

Examples of the hard monomer include methyl acrylate (Tg10 ° C.), methyl methacrylate (Tg105 ° C.), ethyl methacrylate (Tg65 ° C.), n-butyl methacrylate (Tg20 ° C.), isobutyl methacrylate (Tg48 ° C.), and the like. T-butyl methacrylate (Tg 107 ° C), n-stearyl acrylate (Tg 30 ° C), n-stearyl methacrylate (Tg 38 ° C), cyclohexyl acrylate (Tg 15 ° C), cyclohexyl methacrylate (Tg 66 ° C), phenoxyethyl acrylate (Tg 5 ° C.), Phenoxyethyl methacrylate (Tg 54 ° C.), benzyl methacrylate (Tg 54 ° C.), Isobornyl acrylate (Tg 94 ° C.), Isobornyl methacrylate (Tg 180 ° C.), Acryloylmorpholine (Tg 145 ° C.), Adamanthyl acrylate (Tg115 ° C.) ℃), adamantyl methacrylate (Tg141 ℃), acrylic acid (Tg105 ℃), dimethylacrylamide (Tg89 ℃), acrylamide (Tg165 ℃) and other acrylic monomers, vinyl acetate (Tg32 ℃), styrene (Tg80 ℃) and the like. Can be mentioned.

The (meth) acrylic polymer A contains a reactive functional group-containing monomer as a monomer unit constituting the polymer, and thus heats described later via the reactive functional group derived from the reactive functional group-containing monomer. Reacts with cross-linking agents. As a result, a crosslinked structure (three-dimensional network structure) is formed as a whole, and a pressure-sensitive adhesive having a desired cohesive force can be obtained.

Examples of the reactive functional group-containing monomer contained in the (meth) acrylic polymer A as a monomer unit constituting the polymer include a monomer having a hydroxyl group in the molecule (monomer containing a hydroxyl group) and a monomer having a carboxy group in the molecule. (Carboxy group-containing monomer), a monomer having an amino group in the molecule (amino group-containing monomer), and the like are preferably mentioned. Of these, hydroxyl group-containing monomers are particularly preferable because many of them have a glass transition temperature (Tg) of 0 ° C. or lower.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and (meth). ) Hydroxyalkyl esters of (meth) acrylic acid such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylic acid can be mentioned. Among them, 2-hydroxyethyl acrylate from the viewpoint of glass transition temperature (Tg), reactivity of the obtained (meth) acrylic polymer A with a heat-crosslinking agent of a hydroxyl group, and copolymerizability with other monomers. , 2-Hydroxypropyl acrylate, 3-hydroxypropyl acrylate, and 4-hydroxybutyl acrylate are preferred. These may be used alone or in combination of two or more.

Examples of the carboxy group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These may be used alone or in combination of two or more.

Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, n-butylaminoethyl (meth) acrylate and the like. These may be used alone or in combination of two or more.

The (meth) acrylic polymer A preferably contains a reactive functional group-containing monomer as a lower limit value of 0.1% by mass or more, particularly 0.5% by mass or more, as a monomer unit constituting the polymer. It is preferable that the content is 1% by mass or more. The (meth) acrylic polymer A preferably contains the above-mentioned reactive functional group-containing monomer as an upper limit of 10% by mass or less, particularly preferably 8% by mass or less, and further contains 5% by mass or less. Is preferable. This tends to make it easier to suppress the generation of cracks or bubbles in the pressure-sensitive adhesive layer during bending.

The (meth) acrylic polymer A may not contain a carboxy group-containing monomer, particularly acrylic acid, which is also a hard monomer, as a monomer unit constituting the polymer. Since the carboxy group is an acid component, a transparent conductive film such as tin-doped indium oxide (ITO), a metal film, or a metal that causes a problem due to the acid to the object to which the pressure-sensitive adhesive is attached because the carboxy group-containing monomer is not contained. Even when a mesh or the like is present, those defects (corrosion, change in resistance value, etc.) due to acid can be suppressed.

If desired, the (meth) acrylic polymer A may contain another monomer as a monomer unit constituting the polymer. As the other monomer, a monomer containing no reactive functional group is preferable so as not to interfere with the action of the reactive functional group-containing monomer. Examples of the other monomers include (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, as well as a glass transition temperature (Tg) of -40 as a homopolymer. Examples thereof include monomers having a temperature exceeding 0 ° C. or lower than 0 ° C. (hereinafter, may be referred to as “medium Tg alkyl acrylate”). Examples of the medium Tg alkyl acrylate include ethyl acrylate (Tg-20 ° C.), isobutyl acrylate (Tg-26 ° C.), 2-ethylhexyl methacrylate (Tg-10 ° C.), and n-lauryl acrylate (Tg-23 ° C.). ℃), isostearyl acrylate (Tg-18 ℃) and the like. These may be used alone or in combination of two or more.

The polymerization mode of the (meth) acrylic polymer A may be a random copolymer or a block copolymer.

The lower limit of the weight average molecular weight of the (meth) acrylic polymer A is preferably 200,000 or more, particularly preferably 300,000 or more, and further preferably 400,000 or more. When the lower limit of the weight average molecular weight of the (meth) acrylic polymer A is equal to or higher than the above, problems such as seepage of the adhesive are suppressed.

The upper limit of the weight average molecular weight of the (meth) acrylic polymer A is preferably 2 million or less, particularly preferably 1.5 million or less, and further preferably 1.3 million or less. When the upper limit of the weight average molecular weight of the (meth) acrylic polymer (A) is not more than the above, the flexibility of the pressure-sensitive adhesive layer can be ensured, and the effect of the present invention can be easily exhibited.

In the pressure-sensitive adhesive composition A, one type of (meth) acrylic polymer A may be used alone, or two or more types may be used in combination.

When the pressure-sensitive adhesive composition A containing the heat-crosslinking agent is heated, the heat-crosslinking agent cross-links the (meth) acrylic polymer A to form a three-dimensional network structure. As a result, the cohesive force can be improved while ensuring the flexibility of the pressure-sensitive adhesive, and when applied to the laminated body, it is possible to obtain a hardness capable of improving the surface hardness of the laminated body.

The thermal cross-linking agent may be any as long as it reacts with the reactive group of the (meth) acrylic polymer A. For example, an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an amine-based cross-linking agent, a melamine-based cross-linking agent, and the like. Examples thereof include aziridine-based cross-linking agent, hydrazine-based cross-linking agent, aldehyde-based cross-linking agent, oxazoline-based cross-linking agent, metal alkoxide-based cross-linking agent, metal chelate-based cross-linking agent, metal salt-based cross-linking agent, ammonium salt-based cross-linking agent and the like. Among the above, when the reactive group of the (meth) acrylic polymer A is a hydroxyl group, it is preferable to use an isocyanate-based cross-linking agent having excellent reactivity with the hydroxyl group. The thermal cross-linking agent may be used alone or in combination of two or more.

The isocyanate-based cross-linking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanates, and alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate. , And their biurets, isocyanurates, and adducts, which are reactants with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Of these, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate, are preferable from the viewpoint of reactivity with hydroxyl groups.

Examples of the epoxy-based cross-linking agent include 1,3-bis (N, N-diglycidyl aminomethyl) cyclohexane, N, N, N', N'-tetraglycidyl-m-xylylenediamine, and ethylene glycol diglycidyl ether. , 1,6-Hexanediol diglycidyl ether, trimethylpropan diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.

The content of the heat-crosslinking agent in the pressure-sensitive adhesive composition A is preferably 0.01% by mass or more, and preferably 0.05% by mass or more, based on 100% by mass of the (meth) acrylic polymer A. More preferably, it is 0.1% by mass or more. Further, the content is preferably 1% by mass or less, more preferably 0.8% by mass or less, and further preferably 0.5% by mass or less. When the content of the thermal cross-linking agent is in the above range, it is possible to more easily obtain an appropriate hardness by improving the cohesive force.

The pressure-sensitive adhesive composition A preferably contains the above-mentioned silane coupling agent. As a result, the pressure-sensitive adhesive layer has improved adhesion between each member in the laminated body, and has more excellent durability against bending.

The silane coupling (SC) agent is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule, which has good compatibility with the (meth) acrylic polymer A and has light transmittance. ..

Examples of the silane coupling agent include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacrypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 2- (3). , 4-Epoxycyclohexyl) Silicon compounds having an epoxy structure such as ethyltrimethoxysilane, mercapto group-containing silicon compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, Amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3 -Chloropropyltrimethoxysilane, 3-isocyanuppropyltriethoxysilane, or at least one of them and an alkyl group-containing silicon compound such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, or ethyltrimethoxysilane. Examples thereof include condensates. These may be used individually by 1 type, and may be used in combination of 2 or more type.

The content of the silane coupling agent in the pressure-sensitive adhesive composition A is preferably 0.01% by mass or more, preferably 0.05% by mass or more, based on 100% by mass of the (meth) acrylic polymer A. Is more preferable, and 0.1% by mass or more is further preferable. Further, the content is preferably 1% by mass or less, more preferably 0.5% by mass or less, and further preferably 0.3% by mass or less. When the content of the silane coupling agent is in the above range, the adhesion between the members in the laminate can be further improved.

The above-mentioned various additives can be added to the pressure-sensitive adhesive composition A, if desired. In the present specification, the polymerization solvent and the diluting solvent are not included in the additives constituting the pressure-sensitive adhesive composition A.

The (meth) acrylic polymer A can be produced by polymerizing a mixture of monomers constituting the polymer by a normal radical polymerization method. The polymerization of the (meth) acrylic polymer A is preferably carried out by a solution polymerization method using a polymerization initiator, if desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone and the like, and two or more of them may be used in combination.

Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more of them may be used in combination. Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane1-carbonitrile), and 2, , 2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate) , 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-hydroxymethylpropionitrile), 2,2'-azobis [2- (2-imidazolin-2-yl) Propane] and the like.

Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxy dicarbonate, di-n-propyl peroxy dicarbonate, and di (2-ethoxyethyl) peroxy. Examples thereof include dicarbonate, t-butylperoxyneodecanoate, t-butylperoxyvivarate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, and diacetyl peroxide.

In the above polymerization step, the weight average molecular weight of the obtained polymer can be adjusted by adding a chain transfer agent such as 2-mercaptoethanol.

Once the (meth) acrylic polymer A is obtained, a thermal cross-linking agent, a silane coupling agent and, if desired, an additive and a diluting solvent are added to the solution of the (meth) acrylic polymer A and mixed thoroughly. A solvent-diluted pressure-sensitive adhesive composition A (coating solution) can be obtained. The pressure-sensitive adhesive composition A can be produced by a known method, for example, by collectively mixing each component using a mixer or the like.

If any of the above components is in solid form, or if precipitation occurs when mixed with other components in an undiluted state, the component may be dissolved in a diluting solvent by itself in advance. It may be diluted and then mixed with other ingredients.

Examples of the diluting solvent include aliphatic hydrocarbon solvents such as hexane, heptane and cyclohexane, aromatic hydrocarbon solvents such as toluene and xylene, halogenated hydrocarbon solvents such as methylene chloride and ethylene chloride, and methanol. Alcohol-based solvents such as ethanol, propanol, butanol, 1-methoxy-2-propanol, ketone solvents such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone, ester solvents such as ethyl acetate and butyl acetate, ethyl cellosolve, etc. Cellosolve solvent etc. is used.

The concentration and viscosity of the pressure-sensitive adhesive composition A (coating solution) prepared in this manner may be any range as long as it can be coated, and is not particularly limited and can be appropriately selected depending on the situation. For example, the concentration of the pressure-sensitive adhesive composition A can be adjusted to be 10 to 60% by mass in the solution. When obtaining the coating solution, the addition of a diluting solvent or the like is not a necessary condition, and if the pressure-sensitive adhesive composition A has a coatable viscosity or the like, the diluting solvent may not be added. In this case, the pressure-sensitive adhesive composition A becomes a coating solution using the polymerization solvent of the (meth) acrylic polymer A as it is as a diluting solvent.

The pressure-sensitive adhesive layer can be obtained by cross-linking the pressure-sensitive adhesive composition A. Crosslinking of the pressure-sensitive adhesive composition A can be performed by heat treatment. The heat treatment can also serve as a drying treatment for volatilizing the diluting solvent or the like from the coating film of the pressure-sensitive adhesive composition A applied to the desired object.

The heating temperature in the heat treatment is preferably 50 to 150 ° C, more preferably 70 to 120 ° C. The heating time in the heat treatment is preferably 10 seconds to 10 minutes, more preferably 50 seconds to 2 minutes.

After the heat treatment, if necessary, a curing period of about 1 to 2 weeks can be provided at room temperature (for example, 23 ° C., 50% RH). If this curing period is required, an adhesive layer can be formed after the curing period has elapsed. When the curing period is not required, the pressure-sensitive adhesive layer can be formed after the above-mentioned heat treatment is completed.

By the above heat treatment (and curing), the (meth) acrylic polymer A is sufficiently crosslinked via a crosslinking agent to form a crosslinked structure, whereby an adhesive layer can be obtained.

<Adhesive sheet>
The pressure-sensitive adhesive sheet can include a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition A. This pressure-sensitive adhesive layer can be formed by applying the pressure-sensitive adhesive composition A onto a substrate. When the active energy ray-curable pressure-sensitive adhesive composition is used as the pressure-sensitive adhesive composition A, the formed pressure-sensitive adhesive layer can be irradiated with active energy rays to obtain a cured product having a desired degree of curing. When a thermosetting pressure-sensitive adhesive composition is used as the pressure-sensitive adhesive composition, a cured product having a desired degree of curing can be obtained by subjecting the formed pressure-sensitive adhesive layer to heat treatment (and curing).

The base material may be a release film that has undergone a mold release treatment. The pressure-sensitive adhesive sheet can be produced by applying the pressure-sensitive adhesive composition A on a release film to form a pressure-sensitive adhesive layer in the form of a sheet, and then adhering another release film on the pressure-sensitive adhesive layer. it can.

As a method of applying the coating liquid of the pressure-sensitive adhesive composition A, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method and the like can be used.

[Circular polarizing plate]
The laminated body 100 includes a circular polarizing plate 30. The circular polarizing plate 30 can be provided with a linear polarizing plate and a retardation layer, and the linear polarizing plate can be arranged on the pressure-sensitive adhesive layer 20 side. When the laminated body 100 is applied to the display device, the circular polarizing plate 30 is located on the side far from the surface of the laminated body 100 applied to the display device as described above. When the laminated body 100 is applied to a display device, the circular polarizing plate 30 can convert light (external light) incident on the laminated body 100 from the visual side of the display device into circularly polarized light. Further, since the circularly polarizing plate 30 can absorb the external light reflected by the display element in the image display device, the laminated body 100 can be provided with a function as an antireflection film. The circularly polarizing plate 30 preferably contains either a film formed from a liquid crystal layer or a polyvinyl alcohol-based resin film as described later. In particular, the circularly polarizing plate 30 preferably includes a film formed from a liquid crystal layer or a polyvinyl alcohol-based resin film as a polarizer of a linearly polarizing plate.

<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 may include a stretched film on which a dichroic dye is adsorbed, a film on which the dichroic dye is applied and cured, or the like as a polarizer. The film obtained by applying and curing the dichroic dye is obtained by applying and curing a composition containing a dichroic dye having liquid crystal properties or a composition containing a dichroic dye and a polymerizable liquid crystal compound. A film having a layer or the like can be used. Specifically, iodine or a dichroic organic dye can be used as the dichroic dye. For dichroic organic dyes, C.I. I. Included are dichroic direct dyes composed of disuazo compounds such as DIRECT RED 39 and dichroic direct dyes composed of compounds such as trisazo and tetrakisazo. A film coated with a dichroic dye and cured is preferable because there is no limitation in the bending direction as compared with a stretched film on which a dichroic dye is adsorbed.

(A linear polarizing plate in which a stretched film adsorbed with a dichroic dye serves as a polarizer)
Hereinafter, a linear polarizing plate in which a stretched film on which a dichroic dye is adsorbed serves as a polarizer will be described. The stretched film on which the bicolor dye is adsorbed is usually a step of uniaxially stretching the polyvinyl alcohol-based resin film and a step of adsorbing the bicolor dye by dyeing the polyvinyl alcohol-based resin film with the bicolor dye. , A step of treating the polyvinyl alcohol-based resin film on which the bicolor dye is adsorbed with an aqueous boric acid solution, and a step of washing the polyvinyl alcohol-based resin film on which the bicolor dye is adsorbed with water after the treatment with the boric acid aqueous solution. Manufactured by The stretched film produced by the above step on which the dichroic dye is adsorbed may be used as it is as a linear polarizing plate, or may be used as a linear polarizing plate after a transparent protective film is attached to one or both sides thereof. .. The thickness of the polarizer (stretched film on which the dichroic dye is adsorbed) thus obtained is preferably 2 μm to 40 μm.

The polyvinyl alcohol-based resin is obtained by saponifying a 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 acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth) acrylamides having an ammonium group.

The degree of saponification 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, polyvinyl acetal, etc. modified with aldehydes can be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually about 1000 to 10000, preferably in the range of 1500 to 5000.

By forming a film of such a polyvinyl alcohol-based resin, it is possible to obtain a raw film (that is, a polyvinyl alcohol-based resin film) as a material for a polarizer. The method for forming the film of the polyvinyl alcohol-based resin is not particularly limited, and the film can be formed by a known method. The film thickness of the polyvinyl alcohol-based resin film can be, for example, about 1 μm to 100 μm.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing with a dichroic dye, at the same time as dyeing, or after dyeing. When the uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before the boric acid treatment or during the boric acid treatment. Furthermore, it is also possible to perform uniaxial stretching in these a plurality of steps. In uniaxial stretching, rolls having different peripheral speeds may be uniaxially stretched, or thermal rolls may be used to uniaxially stretch. The uniaxial stretching may be a dry stretching in which the stretching is performed in the atmosphere, or a wet stretching in which the polyvinyl alcohol-based resin film is swollen using a solvent. The draw ratio is usually about 3 to 8 times.

The thickness of the linear polarizing plate provided with the stretched film as a polarizer may be, for example, 1 μm or more, 5 μm or more, or 7 μm or more. The thickness of the linear polarizing plate provided with the stretched film as a polarizer may be 100 μm or less, 50 μm or less, 20 μm or less, or 10 μm or less.

The material of the transparent protective film to be bonded to one side or both sides of the polarizer is not particularly limited, but for example, a cyclic polyolefin resin film, a cellulose acetate resin film made of a resin such as triacetyl cellulose or diacetyl cellulose, or polyethylene terephthalate. , Polyethylene naphthalate, polyester resin film made of resin such as polybutylene terephthalate, polycarbonate resin film, (meth) acrylic resin film, polypropylene resin film and other films known in the art. .. From the viewpoint of thinning, the thickness of the transparent protective film is usually 300 μm or less, preferably 200 μm or less, and more preferably 100 μm or less.
The thickness of the transparent protective film is usually 5 μm or more, preferably 20 μm or more. The transparent protective film may or may not have a phase difference.

(A linear polarizing plate in which a film coated with a dichroic dye and cured becomes a polarizer)
Next, a linear polarizing plate in which a film coated with a dichroic dye and cured becomes a polarizer will be described. As the film to which the dichroic dye is applied and cured, the composition containing the dichroic dye having a liquid crystal property as described above or the composition containing the dichroic dye and the polymerizable liquid crystal compound is applied and cured. A film having a layer obtained by the above process (hereinafter, these are collectively referred to as "film formed from a liquid crystal layer") or the like can be used. The film formed from the liquid crystal layer may be used as a linear polarizing plate by peeling off the base material or used as a linear polarizing plate together with the base material, or may be used as a linear polarizing plate after a transparent protective film is attached to one or both sides thereof. Good. As the transparent protective film, the same material as the transparent protective film in which the above-mentioned stretched film is bonded to a linear polarizing plate serving as a polarizer can be used.

Specific examples of the film formed from the liquid crystal layer include the films described in JP2013-37353A, JP2013-33249, and the like.

The film formed from the liquid crystal layer is preferably thin, but if it is too thin, the strength tends to decrease and the processability tends to be inferior. The thickness of the film is usually 20 μm or less, preferably 5 μm or less, and more preferably 0.5 μm or more and 3 μm or less. The thickness of the linear polarizing plate in which the film formed from the liquid crystal layer serves as a polarizer may be, for example, 1 μm or more and 50 μm or less.

<Phase difference layer>
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. 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 transparent protective film described above, 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 is a layer composed of an adhesive or an adhesive for bonding the λ / 4 layer, the λ / 2 layer, and the positive C layer. (Hereinafter, also referred to as “bonded layer”) may be provided.

When the retardation layer is formed from a layer obtained by curing a polymerizable liquid crystal compound, it 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 resin film (the transparent protective 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 layer and a base film. Further, the retardation layer can be bonded to the linear polarizing plate via a bonding layer described later.

(Lated layer)
The bonding layer is a layer composed of an adhesive or an adhesive. As the pressure-sensitive adhesive used as the material of the bonding layer, the same pressure-sensitive adhesive composition as the pressure-sensitive adhesive composition used as the material of the pressure-sensitive adhesive layer 20 can be used, and with other pressure-sensitive adhesives, for example, the material of the pressure-sensitive adhesive layer 20. Different (meth) acrylic adhesives, styrene adhesives, silicone adhesives, rubber adhesives, urethane adhesives, polyester adhesives, epoxy copolymer adhesives and the like can also be used.

Furthermore, the "adhesive" used as the material of the bonding layer refers to an adhesive other than the adhesive (pressure sensitive adhesive), and is clearly distinguished from the adhesive. As the adhesive used as the material of the 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 an active energy ray 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, anionic radicals, and cationic radicals by irradiating them with active energy rays such as ultraviolet rays.

The thickness of the bonding layer is not particularly limited, but when the pressure-sensitive adhesive layer is used as the bonding layer, it is preferably 1 μm or more, 5 μm or more, 10 μm or more, and 15 μm or more. It may be present, usually 50 μm or less, and may be 25 μm or less. When an adhesive layer is used as the bonding layer, the thickness of the bonding layer is preferably 0.1 μm or more, may be 0.5 μm or more, preferably 10 μm or less, and is 5 μm or less. There may be.

[Manufacturing method of laminate]
The laminate 100 can be manufactured by a method including a step of laminating the front plate 10 and the circular polarizing plate 30 via the pressure-sensitive adhesive layer 20. Further, the layers constituting the laminated body 100 can be bonded to each other via the above-mentioned bonding layer, if necessary. When the layers are bonded to each other via the pressure-sensitive adhesive layer 20 or the bonding layer, it is preferable to apply a surface activation treatment such as a corona treatment to one or both of the bonding surfaces in order to improve the adhesion. ..

The circularly polarizing plate 30 can be formed directly on the transparent protective film or the base film as described above, and the transparent protective film or the base film may be incorporated into the laminate 100, or may be incorporated into the laminate 100. It does not have to be peeled off from the circularly polarizing plate 30 to become a component of the laminated body 100.

[Display device]
The display device according to one aspect of the present invention includes the laminated body 100. 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 may have a touch panel function. Even when the laminated body 100 is bent in a moist heat environment, cracks such as cracks and cracks in the laminated body 100 and generation of air bubbles in the adhesive layer 20 are suppressed, so that the laminated body 100 is bent or bent. It is suitable for use in a display device having possible flexibility. As a component used in the display device, for example, in addition to the above image display device, a separator may be included.

The display device is arranged so that the front plate 10 side of the laminated body 100 is on the side opposite to the display element side, that is, on the visual side of the display element of the display device. The display device may be bent with the front plate 10 side on the inside, or may be bent with the front plate 10 side on the outside, but the front plate 10 side may be on the inside. It is preferable that it can be bent. Further, it is also preferable that the display device can be bent with the front plate 10 side on the inside and the front plate 10 side on the outside.

[Back plate]
The display device may further include a back plate. The back plate is preferably laminated on the circular polarizing plate 30 side of the laminated body 100. Specifically, when such a display device is described with reference to the laminated body 100 of FIG. 1, in addition to the front plate 10, the adhesive layer 20, and the circular polarizing plate 30, the back plate is on the circular polarizing plate 30 side of the laminated body 100. Includes aspects of being stacked adjacent to. The back plate can be laminated on the circular polarizing plate 30 via the above-mentioned bonding layer. As the back plate, a touch sensor panel, another plate-like body capable of transmitting light, or the like may be applied, but the back plate is preferably a touch sensor panel. Hereinafter, these components will be described.

<Touch sensor panel>
In the present invention, a touch sensor panel can be used as the back plate. As the touch sensor panel, as long as it is a sensor that can detect the touched position, the detection method is not limited, and the resistance film method, the capacitance coupling method, the optical sensor method, the ultrasonic method, and the electromagnetic induction coupling method are used. Examples of touch sensor panels include a method and a surface acoustic wave method. Since the cost is low, a touch sensor panel of a resistance film type or a capacitance coupling type is preferably used.

An example of a resistance film type touch sensor panel is a pair of substrates arranged to face 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 through 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.

The thickness of the touch sensor panel may be, for example, 5 μm or more and 2000 μm or less, and may be 5 μm or more and 100 μm or less.

<Plate-shaped body that can transmit light>
In the present invention, a plate-like body capable of transmitting light can be used as the back plate, for example, a plate-like body (resin plate, resin sheet, resin film, glass plate, glass film, etc.) that can be used as a front plate. The same can be used as a plate-like body capable of transmitting light.

The thickness of the plate-like body capable of transmitting light 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 capable of transmitting light may be composed of only one layer, or may be composed of two or more layers.

From the above, the stacking order of the components in the display device is, for example, front plate / adhesive layer / circular polarizing plate / separator, front plate / adhesive layer / circular polarizing plate / organic EL display element, front plate / adhesive layer. / Circular polarizing plate / Touch sensor panel / Organic EL display element and the like.

The display device according to one aspect of 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, 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 to these examples. When the terms "%" and "parts" are used in the present embodiments, these terms mean mass% and parts by mass unless otherwise specified.

[Measuring method]
The measurement method and calculation method of each physical property value (weight average molecular weight, compression restoration rate, etc.) used in this example are as follows.

<Measurement of weight average molecular weight (Mw)>
The weight average molecular weight (Mw) of the (meth) acrylic polymer A was determined by the following size exclusion chromatography (SEC) using tetrahydrofuran as the mobile phase as the polystyrene-equivalent number average molecular weight (Mn).

Specifically, the (meth) acrylic polymer A to be measured was dissolved in tetrahydrofuran at a concentration of about 0.05% by mass, and 10 μL was injected into SEC. The mobile phase was flowed at a flow rate of 1.0 mL / min. PLgel MIXED-B (manufactured by Polymer Laboratories) was used as the column. A UV-VIS detector (trade name: Agilent GPC) was used as the detector.

<Layer thickness>
The measurement was performed using a contact type film thickness measuring device (“MS-5C” manufactured by Nikon Corporation). However, the polarizer and the retardation layer were measured using a laser microscope (“OLS3000” manufactured by Olympus Corporation).

<Compression / restoration rate of laminated body>
By using the following evaluation device and evaluation conditions, the compression restoration rate of the laminated body, B (%), was determined. Specifically, first, a test piece having a length of 50 mm and a width of 50 mm was cut out from a laminate having a thickness of A (μm) using a super cutter. Next, as shown in FIG. 2, at the center of the surface of the test piece on the front plate side, a spherical indenter Z (Ball indenter) having a diameter of 0.4 mm is applied with a force of 100 mN from the surface toward the inside of the laminate. A dent (recess) was formed by pushing in for 60 seconds, and the maximum depth x of this dent was determined. Further, 60 seconds after the spherical indenter Z was removed from the laminate, the depth y of the recess to be recovered in the recess was determined. Finally, B (%) was calculated by calculating the depth y of the recess to be recovered / the maximum depth xx100. The thickness of the laminated body, A (μm), can be determined by the contact-type film thickness measuring device described above.

Evaluation device: Nano Indicator
Evaluation conditions: ISO-FDIS 14577-1 2013 (E), using a ball indenter with a diameter of 0.4 mm Evaluation temperature: 25 ° C.
Power: 100mN
Pressing time: 60 seconds Waiting time after indenter removal: 60 seconds Creeping: 5 seconds.

<Gel fraction of adhesive layer>
The gel fraction of the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer A11 and the pressure-sensitive adhesive layer A12 described later) was measured according to the following (I) to (V).
(I) A pressure-sensitive adhesive layer having an area of about 8 cm × about 8 cm and a metal mesh (the mass thereof is Wm) made of SUS304 having an area of about 10 cm × about 10 cm are bonded together.
(II) Weigh the mass of the bonded product obtained in (I) above, set the mass to Ws, then fold it four times so as to wrap the adhesive layer, staple it with a stapler, and then weigh it. , Let the mass be Wb.
(III) The mesh stapled in (II) above is placed in a glass container, 60 mL of ethyl acetate is added and immersed, and then the glass container is stored at room temperature for 3 days.
(IV) The mesh of (III) above was taken out from the glass container, dried at 120 ° C. for 24 hours, and then weighed to give a mass of Wa.
(V) The pressure-sensitive adhesive layer by substituting the above-mentioned weighed mass into the formula of gel fraction (mass%) = [{Wa- (Wb-Ws) -Wm} / (Ws-Wm)] × 100. The gel fraction of was calculated.

[Manufacturing of adhesive sheet]
[1] Production of Adhesive Sheet A11 (1) Preparation of (Meta) Acrylic Polymer A In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer and a stirrer, 81.8 parts by mass of acetone and butyl acrylate 98. A mixed solution of 6 parts by mass, 1.0 part by mass of 2-hydroxyethyl acrylate and 0.4 parts by mass of acrylic acid was charged, and the internal temperature was 55 ° C. while replacing the air in the container with nitrogen gas to make it oxygen-free. I raised it to. Then, a total amount of a solution prepared by dissolving 0.14 parts by mass of azobisisobutyronitrile (polymerization initiator) in 10 parts by mass of acetone was added. Internal temperature while continuously adding acetone into the reaction vessel at an addition rate of 17.3 parts by mass / hr so that the concentration of the acrylic resin excluding the monomer becomes 35% by mass 1 hour after the addition of the above-mentioned polymerization initiator. The temperature was kept at 54 to 56 ° C. for 12 hours, and finally acetone was added to adjust the concentration of the acrylic resin to 20% by mass. The obtained acrylic resin had a polystyrene-equivalent weight average molecular weight Mw of 1270000 by GPC. This is referred to as (meth) acrylic polymer A. The structural unit derived from 2-hydroxyethyl acrylate, which is a hydroxyl group-containing unsaturated monomer in the (meth) acrylic polymer A, is 1% by mass, and is derived from acrylic acid, which is a carboxyl group-containing unsaturated monomer. The structural unit to be used is 0.4% by mass.

(2) Preparation of Adhesive Composition A11 100 parts by mass (solid content conversion value; the same applies hereinafter) of the (meth) acrylic polymer A obtained in the above step and polyisocyanate as a thermal cross-linking agent B (manufactured by Tosoh Corporation, Co., Ltd.) The product name "Coronate L") and 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., product name "KBM403") as the silane coupling agent C are mixed, and the mixture is sufficiently stirred and methyl ethyl ketone is used. By diluting, a coating solution of the pressure-sensitive adhesive composition A11 was obtained. Table 1 shows each formulation (solid content conversion value) of the pressure-sensitive adhesive composition A11 when the (meth) acrylic polymer is 100 parts by mass (solid content conversion value). The abbreviation "BA" in Table 1 represents n-butyl acrylate, "2HEA" represents 2-hydroxyethyl acrylate, and "AA" represents acrylic acid. The Tg (° C.) of these BA, 2HEA and AA was determined by differential thermal analysis (DTA).

(3) Production of Adhesive Sheet A11 By applying the coating solution of the pressure-sensitive adhesive composition A11 to the peeling-treated surface of the first release film (manufactured by Lintec Corporation, product name "SP-PET752150") with a knife coater. A coating was formed. A coating layer was formed by heat-treating the coated material at 90 ° C. for 1 minute. Next, the coating layer on the first release film and the second release film (manufactured by Lintec Corporation, product name "SP-PET382120") are brought into contact with the release-treated surface of the second release film. The pressure-sensitive adhesive sheet A11 having a pressure-sensitive adhesive layer having a thickness of 20 μm formed by using the pressure-sensitive adhesive composition A11 by laminating and curing under the conditions of 23 ° C. and 50% RH for 7 days, that is, the first release film. A pressure-sensitive adhesive sheet A11 having the structure of / pressure-sensitive adhesive layer (thickness: 20 μm) / second release film was produced. The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive sheet A11 in this embodiment is also referred to as a pressure-sensitive adhesive layer A11.

[2] Production of Adhesive Sheet A12 (1) Preparation of (Meta) Acrylic Polymer A The (meth) acrylic polymer A used for producing the adhesive sheet A11 was prepared.

(2) Preparation of Adhesive Composition A12 With respect to 100 parts by mass of the (meth) acrylic polymer A, the amount of Coronate L, which is a heat-crosslinking agent, is as shown in Table 1, but the pressure-sensitive adhesive composition A11. A coating solution of the pressure-sensitive adhesive composition A12 was obtained by using the same preparation method.

(3) Production of Adhesive Sheet A12 The pressure-sensitive adhesive sheet A12 was produced by using the coating solution of the pressure-sensitive adhesive composition A12 in the same manner as in the production process of the pressure-sensitive adhesive sheet A11. However, the pressure-sensitive adhesive sheet A12 is composed of a first release film / an adhesive layer (thickness: 25 μm) / a second release film. The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive sheet A12 in this embodiment is also referred to as a pressure-sensitive adhesive layer A12.

Table 1 shows each formulation (solid content conversion value) of the pressure-sensitive adhesive composition A11 and the pressure-sensitive adhesive composition A12 when the (meth) acrylic polymer A is 100 parts by mass (solid content conversion value). Table 1 also shows the values of the gel fractions of the pressure-sensitive adhesive layer A11 and the pressure-sensitive adhesive layer A12 obtained by the above method.

Furthermore, CEF3005 and CEF3006 (both manufactured by 3M, USA) were prepared as commercially available adhesive sheets. The CEF3005 is composed of a first release film / adhesive layer (thickness: 125 μm) / second release film, and the CEF3006 is composed of a first release film / adhesive layer (thickness: 150 μm) / second release film. It is a composition.

[Example 1]
[Preparation of each element constituting the laminated body]
<Preparation of front plate (window film)>
As a front plate, a polyimide film (thickness 40 μm) having a hard coat layer (thickness 10 μm) on one side was prepared. Therefore, the thickness of the front plate is 50 μm.

<Preparation of circular polarizing plate>
An alignment film composition was applied to one side of a TAC film (manufactured by Konica Minolta Co., Ltd.) having a thickness of 25 μm, dried and irradiated with polarized UV to form a photoalignment film. A composition containing a dichroic dye and a polymerizable liquid crystal compound is applied onto the photoalignment film, dried, and then the polymerizable liquid crystal compound is cured by irradiation with ultraviolet rays to form a polarizer (thickness 2.5 μm). did. A protective layer composition containing polyvinyl alcohol and water was applied and dried on the surface of the polarizer opposite to the TAC film side to form a protective layer (thickness 1 μm). In this way, a linear polarizing plate was obtained.

A circular polarizing plate was obtained by laminating the λ / 4 layer side of the retardation film, which will be described later, on the protective layer of the linearly polarizing plate. The retardation film has a thickness of 15 μm and has a structure in which an adhesive layer, a λ / 4 layer, an adhesive layer, and a positive C layer are laminated in this order. Each of the pressure-sensitive adhesive layers had a thickness of 5 μm. The λ / 4 layer had a layer in which the liquid crystal compound was cured and an alignment film, and had a thickness of 2 μm. The positive C layer had a layer in which the liquid crystal compound was cured and an alignment film, and had a thickness of 3 μm. In this way, a circular polarizing plate (length 100 mm × width 100 mm) having a layer structure of “TAC film / photoalignment film / polarizer / protective layer / retardation film” was prepared.

[Manufacturing of laminate]
A laminate was manufactured by the following procedure. First, one surface of the front plate and the surface from which the first release film of the adhesive sheet A12 was peeled off were subjected to corona treatment (output 0.3 kW, processing speed 3 m / min), and then the corona treated surfaces were bonded to each other. .. Further, the surface of the adhesive sheet A12 exposed by peeling the second release film and the surface of the circularly polarizing plate on the linear polarizing plate side (the surface of the TAC film) are subjected to corona treatment, and the corona-treated surfaces are bonded to each other. As a result, the laminate of Example 1 was produced. The laminate of Example 1 has a thickness of 119 μm and a shape of 100 mm in length × 100 mm in width.

[Examples 2 to 4 and Comparative Examples 1 to 4]
By following the same procedure as in Example 1 except that the type and thickness of the pressure-sensitive adhesive layer and the thickness of the laminated body are changed as shown in Table 2, Examples 2 to 4 and Comparative Example 1 -The laminated body of Comparative Example 4 was prepared.

Regarding the laminates of Examples 1 to 4 and Comparative Examples 1 to 4, the thickness and type of the pressure-sensitive adhesive layer, the thickness of the laminate, the compression restoration rate obtained by the above method, and the compression restoration rate / lamination The numerical values of the body thickness (B / A) and the like are shown in Table 2 as a list.

Further, the wet and heat bending durability test and the surface hardness test were carried out on the laminates of Examples 1 to 4 and Comparative Examples 1 to 4 by the method described later. The results are shown in Table 3.

<Moist heat bending durability test>
First, a test piece having a length of 100 mm and a width of 10 mm was cut out from the laminated body of each Example and each Comparative Example using a super cutter. Next, the test piece was left for 24 hours in a moist heat environment of 60 ° C./90% RH. By wrapping each test piece (laminate) exposed to these moist heat environments around a cylindrical mandrel (made of iron) so that its front plate is on the inside, the test piece is bent along the length direction. Wet and heat bending durability test was performed. As a result, the minimum diameter of the mandrel that does not generate cracks such as cracks and cracks on the surface of the front plate of the test piece (laminate) and bubbles in the adhesive layer was determined, and ranked based on the following criteria. In the moist heat bending durability test, it can be evaluated that the smaller the value of this minimum diameter, the better the moist heat bending durability of the laminated body.
S: Cracks in the front plate and air bubbles in the adhesive layer when wrapped around a mandrel with a diameter (φ) of 5 mm or less A: Cracks in the front plate and in the adhesive layer when wrapped around a mandrel with a diameter of more than φ5 mm and φ10 mm or less Bubbles generated B: Cracks on the front plate when wound around a mandrel with a diameter of more than φ10 mm and φ15 mm or less C: Cracks and adhesive on the front plate when wrapped around a mandrel with a diameter of more than φ15 mm and φ20 mm or less Bubbles were generated in the layer D: When wound around a mandrel exceeding φ20 mm, cracks were generated in the front plate and bubbles were generated in the adhesive layer.

<Surface hardness test>
A pencil hardness tester (PHT, manufactured by SUKBO SCIENCE) was used to apply a load of 100 g to the surface of the front plate of the laminate of each example and each comparative example at a temperature of 25 ° C. A concave mark was formed on the surface with a pencil (manufactured by Mitsubishi Pencil Co., Ltd., core hardness is 6B). In this case, the surface hardness of the laminates of each Example and each Comparative Example was evaluated by determining the time until the recess marks disappeared and ranking them based on the following criteria. In this surface hardness test, it can be evaluated that the shorter the time until the recess marks disappear, the better the surface hardness.
A: Recess marks disappeared in less than 30 minutes B: Recess marks disappeared in 30 minutes or more and less than 60 minutes C: Recess marks disappeared in 60 minutes or more and less than 90 minutes D: Recess marks disappeared even after 90 minutes passed Did not disappear.

According to the above, Examples 1 to 4 satisfying the relationship of 0.6 ≦ B / A ≦ 2 have a wet heat bending with respect to Comparative Examples 1 to 4 having a relationship of B / A <0.6. Both durability and surface hardness were excellent.

100 laminate, 10 front plate, 11 hard coat layer, 12 resin film, 20 adhesive layer, 30 circular polarizing plate, x maximum depth, y recovery dent depth, Z spherical indenter.

Claims

A laminate including a front plate, a circular polarizing plate, and an adhesive layer interposed between the front plate and the circular polarizing plate.
When the thickness of the laminated body is A (μm) and the compression recovery rate of the laminated body is B (%), the laminated body satisfies the relationship of 0.6 ≦ B / A ≦ 2.
The B (%) is the maximum of the dent formed by pushing a spherical indenter having a diameter of 0.4 mm from the surface of the laminated body on the front plate side toward the inside of the laminated body with a force of 100 mN for 60 seconds. A laminate that is the ratio (%) of the depth of the recess that recovers when the spherical indenter is removed from the laminate to the depth.
The laminate according to claim 1, wherein the A (μm) is 150 μm or less.
The laminate according to claim 1 or 2, wherein the circularly polarizing plate includes either a film formed from a liquid crystal layer or a polyvinyl alcohol-based resin film.
The laminate according to any one of claims 1 to 3, wherein the front plate is either a resin film or a resin film with a hard coat layer having a hard coat layer on at least one surface of the resin film.
A display device including the laminate according to any one of claims 1 to 4.
The display device further includes a back plate.
The display device according to claim 5, wherein the back plate is laminated on the circular polarizing plate side of the laminated body.
The display device according to claim 6, wherein the back plate is a touch sensor panel.
The display device according to any one of claims 5 to 7, which can be bent with the front plate side inside.