JP2020140009A - Laminate - Google Patents

Abstract

To provide a laminate which offers superior adhesive force, and prevents air bubble generation even when the laminate is repeatedly bent with a front plate side on the outside.SOLUTION: A laminate provided herein comprises a front plate, a first adhesive layer made of a first adhesive composition, a polarizer layer, a second adhesive layer made of a second adhesive composition, and a back plate arranged in the described order, and satisfies the following conditional expression (1): G1≥G2 ...(1), where G1 [Pa] represents a shear modulus of the first adhesive layer at 25°C, and G2 [Pa] represents a shear modulus of the second adhesive layer at 25°C, and where the first and second adhesive layers have a gel fraction in a range of 45-85%, inclusive.SELECTED DRAWING: Figure 1

Description

The present invention relates to a laminate.

Japanese Unexamined Patent Publication No. 2018-28873 (Patent Document 1) describes a laminate for a flexible image display device having a plurality of pressure-sensitive adhesive layers.

JP-A-2018-288573

When a display device including a front plate and a laminate having a plurality of pressure-sensitive adhesive layers is repeatedly bent with the front plate side facing outward, bubbles may be generated in the pressure-sensitive adhesive layer in the laminate. In addition, the adhesive strength of the pressure-sensitive adhesive layer is weak, and floating or peeling may occur between the pressure-sensitive adhesive layer and the adherend member.

An object of the present invention is to provide a laminated body in which the generation of air bubbles is suppressed and the adhesive strength is excellent even when the front plate side is turned to the outside and repeatedly bent.

The present invention provides the following laminates, pressure-sensitive adhesive compositions and pressure-sensitive adhesive sheets.
[1] A front plate, a first pressure-sensitive adhesive layer formed by using the first pressure-sensitive adhesive composition, a polarizer layer, and a second pressure-sensitive adhesive layer formed by using the second pressure-sensitive adhesive composition. Including the back plate and in this order,
Assuming that the shear modulus of the first pressure-sensitive adhesive layer at a temperature of 25 ° C. is G1 [Pa] and the shear modulus of the second pressure-sensitive adhesive layer at a temperature of 25 ° C. is G2 [Pa], the following relational expression (1) ):
G1 ≧ G2 (1)
The filling,
The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are laminates having a gel fraction of 45% or more and 85% or less.
[2] The first pressure-sensitive adhesive composition and the second pressure-sensitive adhesive composition both contain a (meth) acrylic polymer.
The laminate according to [1], wherein the (meth) acrylic polymer has a structural unit derived from a monomer having a reactive functional group of less than 5% by mass based on the total mass.
[3] The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer both contain a (meth) acrylic polymer.
The laminate according to [1] or [2], wherein the (meth) acrylic polymer has a weight average molecular weight (Mw) of 200,000 or more and 1.5 million or less.
[4] The laminate according to any one of [1] to [3], wherein the back plate is a touch sensor panel.
[5] A display device including the laminate according to any one of [1] to [4].
[6] The display device according to [6], which can be bent with the front plate side facing outward.

According to the present invention, it is possible to provide a laminated body having excellent adhesive strength by suppressing the generation of air bubbles even when the front plate side is turned to the outside and repeatedly bent.

It is the schematic sectional drawing which shows an example of the laminated body which concerns on this invention. It is the schematic sectional drawing which shows an example of the laminated body which concerns on this invention. It is the schematic explaining the method of a flexibility test. It is sectional drawing which shows typically the manufacturing method of the laminated body of this invention.

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

<Laminated body>
FIG. 1 shows a schematic cross-sectional view of the laminated body according to one aspect of the present invention. The laminate 100 includes a front plate 101, a first pressure-sensitive adhesive layer 102, a polarizer layer 103, a second pressure-sensitive adhesive layer 104, and a back plate 105 in this order. The first pressure-sensitive adhesive layer 102 is formed from the first pressure-sensitive adhesive composition, and the second pressure-sensitive adhesive layer 104 is formed from the second pressure-sensitive adhesive composition. Hereinafter, the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104 may be collectively referred to as a pressure-sensitive adhesive layer.

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, etc., but is, for example, 50 μm or more and 4,000 μm or less, preferably 100 μm or more and 2000 μm or less, more preferably. It is 150 μm or more and 1000 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 laminated body 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 laminated body may have corners R-processed, end portions may be notched, or holes may be formed.

The laminated body 100 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 display device may have a touch panel function.

[Physical properties of adhesive layer]
Assuming that the shear modulus of the first pressure-sensitive adhesive layer 102 at a temperature of 25 ° C. is G1 [Pa] and the shear modulus of the second pressure-sensitive adhesive layer 104 at a temperature of 25 ° C. is G2 [Pa], the laminate 100 is as follows. Relational expression (1):
G1 ≧ G2 (1)
The following relational expression (1'):
G1> G2 (1')
Meet. Whether the relational expression (1) or (1') is satisfied
i) How to make a judgment based on each value of G1 and G2,
ii) There is a method of making a judgment based on another combination having the same magnitude relationship as the combination of G1 and G2.

Regarding the other combinations of ii) above, for example, when the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104 have the same thickness, the first reference pressure-sensitive adhesive formed from the first pressure-sensitive adhesive composition. It can be determined by comparing the layer with the second reference pressure-sensitive adhesive layer formed of the second pressure-sensitive adhesive composition. As long as the first reference pressure-sensitive adhesive layer and the second reference pressure-sensitive adhesive layer have the same thickness, the shear modulus G ₀₁ [Pa] of the first reference pressure-sensitive adhesive layer at a temperature of 25 ° C. and the second reference pressure-sensitive adhesive layer agent layer and shear modulus _G 0 2 [Pa] at a temperature 25 ° C. of, but the relationship following (1a):
G ₀ 1 ≧ G ₀ 2 (1a)
If the relational expression (1) is satisfied, it can be considered that the relational expression (1) is satisfied.
G ₀ 1> G ₀ 2 (1'a)
If it satisfies, it can be considered that the relational expression (1') is satisfied. Shear modulus at a temperature 25 ° C. of the first reference pressure-sensitive adhesive layer and the second reference pressure-sensitive adhesive layer having a thickness of 150 [mu] m G _{0 1,} G 0 ₂ is measured according to the measuring method described in the Examples section below ..

The first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104 have a gel fraction of 45% or more and 85% or less, preferably 50% or more and 80% or less. The gel fractions of the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104 are measured according to the measuring method described in the column of Examples described later.

The laminated body 100 can be bent with the front plate 101 side facing outward. When a display device including a laminated body is repeatedly bent with the front plate side facing outward, bubbles may be generated in the adhesive layer. The generation of such bubbles is particularly remarkable in the pressure-sensitive adhesive layer far from the front plate side, that is, in the second pressure-sensitive adhesive layer 104 in the laminate 100. As a result of research by the present inventor, when the shear modulus of the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104 satisfies the relational expression (1) and the gel fraction of each is 45% or more and 85% or less. It has been found that even if the front plate 101 side is turned to the outside and repeatedly bent, air bubbles generated in the pressure-sensitive adhesive layer in the laminated body 100 can be suppressed. More specifically, even if the inner surface of the laminate 100 is repeatedly bent 20,000 times so that the radius of curvature of the inner surface is 3 mm, bubbles generated in the pressure-sensitive adhesive layer in the laminate 100 can be suppressed (hereinafter, excellent "" It is also said to have "normal temperature flexibility"). The room temperature flexibility can be evaluated according to the evaluation method described in the column of Examples described later. The laminated body 100 may be able to be bent with the front plate side facing inward. The display device to which the laminated body 100 is applied can be used as a flexible display that can be bent or wound. In the present specification, the bending includes a form of bending in which a curved surface is formed in the bent portion, and the radius of curvature 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 radius of curvature close to zero or an inner surface refraction angle of 0 degrees.

The shear modulus of the first reference adhesive layer having a thickness of 150 μm at a temperature of 25 ° C. is G ₀ 1 [Pa], and the shear modulus of the second reference adhesive layer having a thickness of 150 μm at a temperature of 25 ° C. is G _0. When 2 [Pa] is set, the following relational expressions (2) and (3):
1.0 × 10 ⁴ ≦ G ₀ 1 ≦ 5.0 × 10 ⁵ (2)
1.0 × 10 ⁴ ≦ G ₀ 2 ≦ 5.0 × 10 ⁵ (3)
, And more preferably the following relational expressions (2a) and (3a):
2.0 × 10 ⁴ ≦ G ₀ 1 ≦ 2.0 × 10 ⁵ (2a)
2.0 × 10 ⁴ ≦ G ₀ 2 ≦ 2.0 × 10 ⁵ (3a)
Meet.

The first pressure-sensitive adhesive composition so that the shear elasticity of the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104 satisfies the relational expression (1) and the gel fractions of each are 45% or more and 85% or less. As a method for preparing the second pressure-sensitive adhesive composition, for example, the pressure-sensitive adhesive layer may be composed of the pressure-sensitive adhesive composition A described later, or the type of monomer constituting the (meth) acrylic polymer A described later may be changed. Examples thereof include a method of adjusting the molecular weight of the (meth) acrylic polymer A and a method of incorporating a compound having an acetoacetoxyethyl group.

[Adhesive composition]
In one form, the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104 are 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. In the present specification, the “(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 both the first pressure-sensitive adhesive composition and the second pressure-sensitive adhesive composition contain a (meth) acrylic polymer, the (meth) acrylic polymer 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.

The (meth) acrylic polymer A has a weight average molecular weight (Mw) of 200,000 or more and 1.5 million or less from the viewpoint of easily satisfying the relational expression (2) or the relational expression (3) in the obtained pressure-sensitive adhesive layer. Is preferable, and more preferably 300,000 or more and 1.2 million or less.

The (meth) acrylic polymer A has a structural unit derived from a monomer having a reactive functional group, preferably less than 5% by mass 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 a (meth) acryloyl group. As a result, the flexibility of the pressure-sensitive adhesive layer is improved, and it tends to be easy to suppress the generation of bubbles in the pressure-sensitive adhesive layer at low temperature and high temperature. In the (meth) acrylic polymer A, the structural unit derived from the monomer having a reactive functional group is more preferably 0.01% by mass or less based on the total mass of the polymer from the viewpoint of suppressing air bubbles at the time of bending. More preferably, it does not have a structural unit derived from a monomer having a reactive functional group, and even more preferably it does not have a hydroxyl group, a carboxyl group, an amino group, an amide group, an epoxy group and a (meth) acryloyl group.

(1) 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 is linear. It can contain a structural unit derived from a (meth) acrylic monomer having an alkyl group having 1 or more and 24 or less carbon atoms in the form of a branched or branched chain. 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, 200,000 or more and 800,000 or less, and preferably 300,000 or more and 700,000 or less from the viewpoint of suppressing air bubbles at the time of bending. The weight average molecular weight (Mw) can be measured according to the measuring method 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 include epoxy compounds and polyols that form an ester bond with a carboxyl group; polyisocyanate compounds that form an amide bond with a carboxyl group, 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 1 part by mass or less, based on 100 parts by mass of the (meth) acrylic polymer A. It is preferably 0.5 parts by mass or less, more preferably 0.1 parts by mass or less, and it is most preferable that the pressure-sensitive adhesive composition A does 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 and electron beams, and has adhesiveness even before irradiation with active energy rays. It is a pressure-sensitive adhesive composition having the property of being able to adhere to an adherend such as, etc., and being cured by irradiation with active energy rays to adjust the adhesion 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 diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, benzyl dimethyl ketal, 1-hydroxycyclohexyl ketone and the like. When the pressure-sensitive adhesive composition A contains a photopolymerization initiator, it may contain one or more. 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 preferably contains a compound having an acetoacetoxyethyl group. At least one of the first pressure-sensitive adhesive composition and the second pressure-sensitive adhesive composition is preferably a pressure-sensitive adhesive composition A containing a compound having an acetoacetoxyethyl group. The pressure-sensitive adhesive composition A containing a compound having an acetoacetoxyethyl group can easily form a first reference pressure-sensitive adhesive layer and a second reference pressure-sensitive adhesive layer satisfying the above-mentioned relational expressions (2) and (3). .. Further, the pressure-sensitive adhesive composition A containing a compound having an acetoacetoxyethyl group can easily form a pressure-sensitive adhesive layer having a gel fraction of 45% or more and 85% or less. The pressure-sensitive adhesive composition A contains a compound having an acetoacetoxyethyl group in 100 parts by mass of the solid content of the pressure-sensitive adhesive composition A, for example, 0.01 part by mass or more and 20 parts by mass or less, preferably 0.1 part by mass or more. It can contain 10 parts by mass or less, more preferably 0.1 parts by mass or more and 8 parts by mass or less.

The compound having an acetoacetoxyethyl group is not particularly limited, and examples thereof include compounds represented by the following formulas.

In the above formula, R ₁ is a hydrogen or methyl group.

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 and other inorganic substances) for imparting light scattering properties. Additives such as powders), antioxidants, UV absorbers, dyes, pigments, colorants, antifoaming agents, corrosion inhibitors, etc. can be included. The pressure-sensitive adhesive composition A preferably does not contain an organic solvent from the viewpoint of preventing the durability from being lowered by 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 formed pressure-sensitive adhesive layer can be irradiated with active energy rays to obtain a cured product having a desired degree of curing.

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

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 2 to 20 carbon atoms in the alkyl group may have a glass transition temperature (Tg) of −40 ° C. or lower as a homopolymer (hereinafter, referred to as “low Tg alkyl acrylate”). .) Is preferable. By containing such a low Tg alkyl acrylate as a constituent monomer unit, the flexibility of the pressure-sensitive adhesive layer is improved, and the generation of bubbles during bending tends to be easily suppressed.

Examples of the low Tg alkyl acrylate include n-butyl acrylate (Tg-55 ° 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. Above all, the obtained pressure-sensitive adhesive layer is a low Tg alkyl acrylate having a homopolymer Tg of −45 ° C. or lower from the viewpoint of easily satisfying the relational expression (2) or the relational expression (3). It is more preferable, and it is particularly preferable that the temperature is −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 preferably contained in an amount of mass% or more. Within such a range, the obtained pressure-sensitive adhesive layer can easily satisfy the relational expression (2) or the relational expression (3).

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. It is more 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.

In the (meth) acrylic polymer A, the glass transition temperature (Tg) as a homopolymer is 0 in order to facilitate setting the glass transition temperature (Tg) of the main polymer of the pressure-sensitive adhesive according to the present embodiment within the above-mentioned range. It is preferable to reduce the content of the monomer exceeding ° C. (hereinafter, sometimes referred to as “hard monomer”) 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. The 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), acryloylmorpholin (Tg 145 ° C), adamantyl acrylate (Tg115 ° C). ℃), adamantyl methacrylate (Tg141 ℃), acrylic acid (Tg103 ℃), 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. It reacts with a cross-linking agent, thereby forming a cross-linked structure (three-dimensional network structure), and a pressure-sensitive adhesive having a desired cohesive force is 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) acrylates such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate can be mentioned. Among them, 2-hydroxyethyl acrylate is obtained from the viewpoints of glass transition temperature (Tg), reactivity of hydroxyl group in the obtained (meth) acrylic polymer A with a thermal cross-linking agent, 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 and n-butylaminoethyl (meth) acrylate. 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. Further, the upper limit value is preferably 10% by mass or less, particularly preferably 8% by mass or less, and further preferably less than 5% by mass. When the (meth) acrylic polymer A contains a reactive functional group-containing monomer, particularly a hydroxyl group-containing monomer, in the above amount as a monomer unit, the obtained pressure-sensitive adhesive layer can easily satisfy the relational expression (2) or the relational expression (3). Become.

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, etc. Even when a metal mesh or the like is present, it is possible to suppress those defects (corrosion, change in resistance value, etc.) due to acid.

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 such 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 of more than ° C. and 0 ° C. or lower (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.). ° C.), isostearyl acrylate (Tg-18 ° C.) 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 weight average molecular weight in the present specification is a standard polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method.

The upper limit of the weight average molecular weight of the (meth) acrylic polymer A is preferably 1.5 million or less, particularly preferably 1.35 million or less, and further preferably 1.2 million or less. When the upper limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is not more than the above, it becomes easy to satisfy the relational expression (2) or the relational expression (3) for the obtained pressure-sensitive adhesive layer.

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 crosslinks the (meth) acrylic polymer A to form a three-dimensional network structure. As a result, the cohesive force of the obtained pressure-sensitive adhesive is improved, and the obtained pressure-sensitive adhesive layer can easily satisfy the relational expression (2) or the relational expression (3).

The thermal cross-linking agent may be any as long as it reacts with the reactive group of the (meth) acrylic polymer A. 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 heat 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. 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 heat-crosslinking agent is in the above range, the obtained pressure-sensitive adhesive layer can easily satisfy the relational expression (2) or the relational expression (3).

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

The silane coupling 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, 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 obtained pressure-sensitive adhesive layer has more preferable adhesion to each member in the flexible laminate to be the adherend.

The various additives described above can be added to the pressure-sensitive adhesive composition A, if desired. 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 an ordinary 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-butylperbenzoate, cumenehydroperoxide, diisopropylperoxydicarbonate, di-n-propylperoxydicarbonate, 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) is obtained.

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

Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, methanol, ethanol, propanol and butanol. Alcohols such as 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve solvents such as ethyl cellosolve are used.

The concentration and viscosity of the 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 adhesive composition P is diluted so as to have a concentration of 10 to 60% by mass. 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 coatingable viscosity or the like, the diluting solvent may not be added. In this case, the pressure-sensitive adhesive composition A is a coating solution in which the polymerization solvent of the (meth) acrylic polymer A is used as it is as the diluting solvent.

A preferable pressure-sensitive adhesive according to the present embodiment is one obtained by cross-linking the pressure-sensitive adhesive composition A. Crosslinking of the pressure-sensitive adhesive composition A can be performed by heat treatment. This heat treatment can also be used 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 of the heat treatment is preferably 50 to 150 ° C, more preferably 70 to 120 ° C. The heating time 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 may be provided at room temperature (for example, 23 ° C., 50% RH). When this curing period is required, an adhesive is formed after the curing period has elapsed, and when the curing period is not required, after the 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, and a pressure-sensitive adhesive is obtained. Such an adhesive easily satisfies the relational expression (2) or the relational expression (3) with respect to the obtained pressure-sensitive adhesive layer.

The pressure-sensitive adhesive sheet according to the present invention includes the pressure-sensitive adhesive layer formed from the above-mentioned pressure-sensitive adhesive composition A according to the present invention. The pressure-sensitive adhesive layer can be formed by applying the pressure-sensitive adhesive composition A onto a substrate. When a thermosetting pressure-sensitive adhesive composition is used as the pressure-sensitive adhesive composition A, the formed pressure-sensitive adhesive layer is heat-treated (and cured) to obtain a cured product having a desired degree of curing. Can be done. The conditions for heat treatment and curing are as described above.

The base material may be a release film that has been subjected to a mold release treatment. The pressure-sensitive adhesive sheet can be produced by forming a layer made of a pressure-sensitive adhesive on a release film in the form of a sheet, and then adhering another release film on the pressure-sensitive adhesive layer.

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.

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.

[Front plate]
The material and thickness of the front plate 101 are not limited as long as it is a plate-like body capable of transmitting light, and the front plate 101 may be composed of only one layer or may be composed of two or more layers. Examples thereof 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 touch sensor panel described later. The front plate can constitute the outermost surface of the display device.

The thickness of the front plate 101 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. 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 101 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, polyether sulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone , Polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyamideimide and the like. 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 101 is preferably a film in which a hard coat layer is provided on at least one surface of the base film from the viewpoint of hardness. As the base film, a film made of the above resin can be used. The hard coat layer may be formed on one surface of the base film or may be formed on both surfaces. By providing the hard coat layer, a resin film having improved hardness and scratchability 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 strength. Additives are not limited, and include inorganic fine particles, organic fine particles, or mixtures thereof.

When the front plate 101 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, 50 μm or more and 1,000 μm or less. By using the glass plate, the front plate 101 having excellent mechanical strength and surface hardness can be constructed.

When the laminate 100 is used in a display device, the front plate 101 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 adjusting function and the like.

[First adhesive layer]
The first pressure-sensitive adhesive layer 102 is a layer that is interposed between the front plate 101 and the polarizer layer 103 and adheres them, and is, for example, a layer composed of a pressure-sensitive adhesive or an adhesive, or some kind of layer. It may be a treated layer. The first pressure-sensitive adhesive layer can be a pressure-sensitive adhesive layer arranged at a position closest to the front plate among the pressure-sensitive adhesive layers constituting the laminated body. The pressure-sensitive adhesive is also called a pressure-sensitive adhesive. As used herein, the term "adhesive" refers to an adhesive other than an adhesive (pressure sensitive adhesive) and is clearly distinguished from an adhesive. The first pressure-sensitive adhesive layer 102 may be one layer or may be composed of two or more layers, but is preferably one layer.

The first pressure-sensitive adhesive layer 20 can be formed directly from the pressure-sensitive adhesive composition or by using a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer formed by using the pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition can be formed from the pressure-sensitive adhesive composition A as described above.

The thickness of the first pressure-sensitive adhesive layer 102 is, for example, preferably 3 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm or less, and may be 20 μm or more.

[Polarizer layer]
Examples of the polarizer layer 103 include a stretched film or a stretched layer on which a dye having absorption anisotropy is adsorbed, a layer obtained by applying and curing a dye having absorption anisotropy, and the like. Examples of the dye having absorption anisotropy include a dichroic dye. As the dichroic dye, specifically, iodine or a dichroic organic dye is used. 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.

As the polarizer layer formed by applying and curing a dye having absorption anisotropy, a composition containing a dichroic dye having liquid crystal properties or a composition containing a dichroic dye and a polymerizable liquid crystal is applied and cured. Examples thereof include a polarizer layer containing a cured product of a polymerizable liquid crystal compound such as a layer obtained by the above-mentioned.
A polarizer layer obtained by applying and curing a dye having absorption anisotropy is preferable because there is no limitation in the bending direction as compared with a stretched film or a stretched layer on which a dye having absorption anisotropy is adsorbed.

[Polarized film or polarizing layer that is a stretched layer]
The polarizer layer, which is a stretched film on which a dye having absorption anisotropy is adsorbed, is usually obtained by dyeing the polyvinyl alcohol-based resin film with a bicolor dye 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 103 is, for example, 2 μm or more and 40 μm or less. The thickness of the polarizer layer 103 may be 5 μm or more, 20 μm or less, further 15 μm or less, and further 10 μm or less.

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 mol% or more and 100 mol% or less, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can also be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1,000 or more and 10,000 or less, preferably 1,500 or more and 5,000 or less.

The polarizer layer, which is a stretched layer on which a dye having absorption anisotropy is adsorbed, is usually a step of applying a coating liquid containing the polyvinyl alcohol-based resin on a base film, and uniaxially stretching the obtained laminated film. Step, A step of dyeing a polyvinyl alcohol-based resin layer of a uniaxially stretched laminated film with a dichroic dye to adsorb the dichroic dye to form a polarizer layer, a film on which the dichroic dye is adsorbed. Can be produced through a step of treating with an aqueous boric acid solution and a step of washing with water after the treatment with the aqueous boric acid solution.
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 or the polarizer layer, which is a stretched layer, may be incorporated into the laminate in a form in which a thermoplastic resin film is bonded to one side or both sides thereof. This thermoplastic resin film can function as a protective film for the polarizer layer 103 or a retardation film. The thermoplastic resin film is, for example, a polyolefin resin such as a chain polyolefin resin (polypropylene resin, etc.), a cyclic polyolefin resin (norbornen resin, etc.); a cellulose resin such as triacetyl cellulose; polyethylene terephthalate, polyethylene na. It can be a film composed of a polyester resin such as phthalate and polybutylene terephthalate; a polycarbonate resin; a (meth) acrylic resin; or a mixture thereof.

From the viewpoint of thinning, the thickness of the thermoplastic resin film is usually 300 μm or less, preferably 200 μm or less, more preferably 100 μm or less, still more preferably 80 μm or less, still more preferably 60 μm or less. Yes, it is usually 5 μm or more, preferably 20 μm or more.

The thermoplastic resin film may or may not have a phase difference.

The thermoplastic resin film can be attached to the polarizer layer 103 by using, for example, an adhesive layer.

[Polarizer layer formed by applying and curing a dye having absorption anisotropy]
As the polarizer layer formed by applying and curing a dye having absorption anisotropy, a composition containing a polymerizable dichroic dye having liquid crystal properties or a composition containing a dichroic dye and a polymerizable liquid crystal is used. Examples thereof include a polarizer layer containing a cured product of a polymerizable liquid crystal compound, such as a layer obtained by applying and curing the substrate film.

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 above.

The polarizing element layer formed by applying and curing a dye having absorption anisotropy may be incorporated into an optical laminate in a form in which a thermoplastic resin film is bonded to one side or both sides thereof. As the thermoplastic resin film, the same one as the thermoplastic resin film that can be used for the stretched film or the polarizer layer that is the stretched layer can be used. The thermoplastic resin film can be bonded to the polarizer layer using, for example, an adhesive layer.

The thickness of the polarizer layer obtained by applying and curing a dye having absorption anisotropy 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.

[Second adhesive layer]
The second pressure-sensitive adhesive layer 104 is a pressure-sensitive adhesive layer arranged between the polarizer layer 103 and the back plate 105. The second pressure-sensitive adhesive layer can be a pressure-sensitive adhesive layer arranged at a position closest to the back plate among the pressure-sensitive adhesive layers constituting the laminated body. The second pressure-sensitive adhesive layer 104 may be one layer or may be composed of two or more layers, but is preferably one layer.

The composition and ingredients of the pressure-sensitive adhesive composition constituting the second pressure-sensitive adhesive layer 104, the type of the pressure-sensitive adhesive composition (whether it is an active energy ray-curable type or a thermosetting type, etc.), and the pressure-sensitive adhesive composition. The additive to be obtained, the method for producing the second pressure-sensitive adhesive layer, and the thickness of the second pressure-sensitive adhesive layer are the same as those shown in the above description of the first pressure-sensitive adhesive layer 102.
The second pressure-sensitive adhesive layer 104 may be the same as or different from the first pressure-sensitive adhesive layer 102 in terms of the composition, composition, thickness, and the like of the pressure-sensitive adhesive composition.

[Back plate]
As the back plate 105, 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 105 may be, for example, 5 μm or more and 2,000 μm or less, preferably 10 μm or more and 1,000 μm or less, and more preferably 15 μm or more and 500 μm or less.

The plate-like body used for the back plate 105 may be composed of only one layer, may be composed of two or more layers, and an example of the plate-like body described in the front plate 101 may be used. it can.

Examples of components used in a normal display device used for the back plate 105 include a separator, a touch sensor panel, an organic EL display element, and the like. The stacking order of the components in the display device is, for example, front plate / circular polarizing plate / separator, front plate / circular polarizing plate / organic EL display element, front plate / circular polarizing plate / touch sensor panel / organic EL display element, front. Examples thereof include a face plate / touch sensor panel / circular polarizing plate / organic EL display element.

(Touch sensor panel)
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 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 resistive film type or a capacitive coupling type is preferably used.

An example of a resistance film type touch sensor panel is a pair of substrates arranged opposite to each other, an insulating spacer sandwiched between the pair of substrates, and a transparent film provided on the inner front surface of each substrate as a resistance film. 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 capacitively coupled 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 2,000 μm or less, and may be 5 μm or more and 100 μm or less.

[Phase difference layer]
The laminated body 100 can further include one layer or two or more retardation layers. The retardation layer is usually arranged between the polarizer layer 103 and the back plate 105. The retardation layer is formed through a first pressure-sensitive adhesive layer 102, a second pressure-sensitive adhesive layer 104, or a layer composed of a pressure-sensitive adhesive or an adhesive other than these layers (hereinafter, also referred to as a bonding layer). (Including other retardation layers.) Can be laminated on top.

[Lated layer]
The bonding layer is a layer arranged between the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104, and is a layer composed of a pressure-sensitive adhesive or an adhesive. The pressure-sensitive adhesive constituting the bonding layer may be the same as those exemplified for the pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer, or other pressure-sensitive adhesives such as ( Meta) Acrylic adhesive, styrene adhesive, silicone adhesive, rubber adhesive, urethane adhesive, polyester adhesive, epoxy copolymer adhesive and the like may be used.

As the adhesive constituting the bonded layer, for example, one or two or more of water-based adhesives, active energy ray-curable adhesives, adhesives and the like can be combined to form the adhesive. 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 includes, for example, a polymerizable compound and a photopolymerizable initiator, a photoreactive resin, and the like. Examples thereof include those containing a binder resin and a photoreactive cross-linking agent. 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 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 may be, for example, 1 μm or more, preferably 1 μm or more and 25 μm or less, more preferably 2 μm or more and 15 μm or less, and further preferably 2.5 μm or more and 5 μm or less.

The laminate 200 shown in FIG. 2 includes a front plate 101, a first pressure-sensitive adhesive layer 102, a polarizer layer 103, a bonding layer 108, and a back plate 105, and includes a first retardation layer 106, a bonding layer 109, and a second. A retardation layer 107 and a second pressure-sensitive adhesive layer 104 are further provided.

Examples of the retardation layer include a positive A plate such as a λ / 4 plate and a λ / 2 plate, a positive C plate, and the like.
The retardation layer may be, for example, a retardation film that can be formed from the above-mentioned thermoplastic resin film, or contains a layer obtained by curing a polymerizable liquid crystal compound, that is, a cured product of the polymerizable liquid crystal compound. It may be a layer, but the latter is preferable.
The thickness of the retardation film may be the same as the thickness of the above-mentioned thermoplastic resin film. The thickness of the retardation layer obtained by curing the polymerizable liquid crystal compound 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 formed by curing the polymerizable liquid crystal compound can be formed by applying a composition containing the polymerizable liquid crystal compound to a base film and curing the composition. 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 described above.
The retardation layer formed by curing the polymerizable liquid crystal compound may be incorporated into the laminate 100 in the form of having an alignment layer and / or a base film. The back plate 105 may be a base film to which the above composition is applied.

As described above, the bonding layer 108 may use an adhesive or an adhesive. This pressure-sensitive adhesive may be the above-mentioned pressure-sensitive adhesive composition A.
As the adhesive, a water-based adhesive or an active energy ray-curable adhesive can be used. Examples of the water-based adhesive include an adhesive composed of 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 means an adhesive that is cured by irradiating it with an active energy ray such as ultraviolet rays, and for example, an adhesive containing a polymerizable compound and a photopolymerization initiator, an adhesive containing a photoreactive resin, and the like. Examples thereof include those containing a binder resin and a photoreactive cross-linking agent.
Examples of the polymerizable compound include a photopolymerizable monomer such as a photocurable epoxy monomer, a photocurable (meth) acrylic monomer, and a photocurable urethane monomer, and an oligomer derived from the photopolymerizable monomer.
Examples of the photopolymerization initiator include substances that generate active species such as neutral radicals, anionic radicals, and cationic radicals when irradiated with active energy rays such as ultraviolet rays. As the active energy ray-curable adhesive containing a polymerizable compound and a photopolymerization initiator, those containing a photocurable epoxy monomer and a photocationic polymerization initiator can be preferably used.

[Manufacturing method of laminate]
The laminate 100 can be manufactured by a method including a step of adhering layers constituting the laminate 100 to each other via an adhesive layer or an adhesive layer. When the layers are bonded to each other via the pressure-sensitive adhesive layer or the adhesive layer, one or both of the bonded surfaces should be subjected to a surface activation treatment such as corona treatment in order to improve the adhesion. Is preferable.
The polarizer layer 103 can be formed directly on the thermoplastic resin film or the base film, and the thermoplastic resin film or the substrate film may be incorporated in the laminate 100, or the polarizer film may be incorporated. It does not have to be peeled off from the layer 103 to become a component of the laminate.

<Display device>
The display device according to the present invention includes the laminate 100 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 may have a touch panel function. The optical laminate is suitable for a flexible display device that can be bent or bent.

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 outward (the side opposite to the display element side, that is, the visual recognition side).

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. The display device according to the present invention is excellent in the visibility of the screen because the distortion of the reflected image reflected on the surface of the front plate is suppressed.

<Adhesive composition>
The pressure-sensitive adhesive composition according to the present invention is preferably the above-mentioned pressure-sensitive adhesive composition A. The pressure-sensitive adhesive composition according to the present invention can be produced by a known method, for example, by collectively mixing each component using a mixer or the like.

<Adhesive sheet>
The pressure-sensitive adhesive sheet according to the present invention preferably contains a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition A. The pressure-sensitive adhesive layer can be formed by applying the pressure-sensitive adhesive composition onto the substrate. When an active energy ray-curable pressure-sensitive adhesive composition is used as the pressure-sensitive adhesive composition, 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, the formed pressure-sensitive adhesive layer can be heat-treated (and cured) to obtain a cured product having a desired degree of curing. ..

The base material may be a release film that has been subjected to a mold release treatment. The pressure-sensitive adhesive sheet can be produced by forming a layer made of a pressure-sensitive adhesive on a release film in the form of a sheet, and then adhering another release film on the pressure-sensitive adhesive layer.

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present invention has excellent heat resistance. When the shear modulus of the reference pressure-sensitive adhesive layer having a thickness of 150 μm formed by the pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive layer at a temperature of 25 ° C. is G ₀ [Pa], the following relational expression is preferable. 4):
1.0 × 10 ⁴ ≦ G ₀ ≦ 5.0 × 10 ⁵ (4)
The following relational expression (4a):
2.0 × 10 ⁴ ≦ G ₀ ≦ 2.0 × 10 ⁵ (4a)
Meet.

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

[Adhesive sheet using thermosetting adhesive composition]
[1] Production of Adhesive Sheet A11 (1) Preparation of (Meta) Acrylic Polymer 54 parts by mass of n-butyl acrylate, 45 parts by mass of 2-ethylhexyl acrylate and 1 part by mass of 4-hydroxybutyl acrylate are copolymerized. To prepare a (meth) acrylic polymer. When the molecular weight of this (meth) acrylic polymer was measured by the method described later, the weight average molecular weight (Mw) was 800,000.

(2) Preparation of Adhesive Composition 100 parts by mass of the (meth) acrylic polymer obtained in the above step (solid content conversion value; the same applies hereinafter) and trimethylolpropane-modified xylylene diisocyanate as a thermal cross-linking agent (Soken Kagaku) 0.25 parts by mass of product name "TD-75" manufactured by Shinetsu Chemical Industry Co., Ltd., and 0.2 mass of 3-glycidoxypropyltrimethoxysilane (product name "KBM403") manufactured by Shinetsu Chemical Industry Co., Ltd. as a silane coupling agent. The parts were mixed, stirred well, and diluted with methyl ethyl ketone to obtain a coating solution of the pressure-sensitive adhesive composition. Table 1 shows each formulation (solid content conversion value) of the pressure-sensitive adhesive composition when the (meth) acrylic polymer is 100 parts by mass (solid content conversion value). The abbreviations and the like shown in Table 1 represent the following.
BA: n-butyl acrylate 2EHA: 2-ethylhexyl acrylate 4HBA: 4-hydroxybutyl acrylate

(3) Production of Adhesive Sheet A11 The coating solution of the obtained pressure-sensitive adhesive composition was applied to the peeling-treated surface of a light separator (manufactured by Lintec Corporation, product name "SP-PET752150") with a knife coater. Then, the coating layer was heat-treated at 90 ° C. for 1 minute to form a coating layer. Next, the coating layer on the light separator obtained above and the heavy separator (manufactured by Lintec Corporation, product name "SP-PET382120") are bonded so that the peeled surface of the separator is in contact with the coating layer. , 23 ° C., 50% RH for 7 days to form a pressure-sensitive adhesive sheet A11 having a pressure-sensitive adhesive layer having a thickness of 25 μm, that is, a light separator / pressure-sensitive adhesive layer (thickness: 25 μm) / heavy separator. An adhesive sheet A11 made of the above material was produced. The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet A11 is referred to as the pressure-sensitive adhesive layer A11. Table 1 shows the measured shear modulus and gel fraction of the adhesive sheet A11. The thickness, shear modulus, and gel fraction of the pressure-sensitive adhesive layer A11 are values measured by a method described later.

[2] Production of Adhesive Sheets A12 to A16 (1) Preparation of (Meta) Acrylic Polymer (Meta) The ratio of each monomer constituting the acrylic polymer is prepared as shown in Table 1, and the production step of the adhesive sheet A11. In the same manner as above, a (meth) acrylic polymer having a weight average molecular weight (Mw) shown in Table 1 was prepared.

(2) Preparation of Adhesive Composition 100 parts by mass of the (meth) acrylic polymer obtained in the above step and trimethylolpropane-modified xylylene diisocyanate as a thermal cross-linking agent (manufactured by Soken Kagaku Co., Ltd., product name "TD-75") ”) And 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., product name“ KBM403 ”) as a silane coupling agent are mixed in the blending ratios shown in Table 1, and the mixture is sufficiently stirred. A coating solution of the pressure-sensitive adhesive composition was obtained by diluting with methyl ethyl ketone.

(3) Production of Adhesive Sheets A12 to A16 Adhesive sheets A12 to A16 were produced in the same manner as in the production process of the adhesive sheet A11 using the coating solution of the obtained adhesive composition. The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets A12 to A16 are designated as pressure-sensitive adhesive layers A12 to A16. Table 1 shows the thickness, shear modulus, and gel fraction of the pressure-sensitive adhesive layers A12 to A16 measured by the methods described below for the pressure-sensitive adhesive sheets A12 to A16.

[Adhesive sheet using active energy ray-curable adhesive composition]
[1] Production of Adhesive Sheet A21 (1) Preparation of (Meta) Acrylic Polymer A21

From 92.9% by mass of 2-ethylhexyl acrylate (2-EHA) monomer and 7% by mass of butyl acrylate (BA) monomer in a 1L reactor equipped with a cooling device so that the nitrogen gas can be refluxed to facilitate temperature control. After the monomer mixture was charged, nitrogen gas was refluxed for 1 hour in order to remove oxygen, and then maintained at 80 ° C. After uniformly mixing the above-mentioned monomer mixture, 0.05% by mass of the photopolymerization initiator benzyldimethylketal (I-651) and 0.05% by mass of 1-hydroxycyclohexylketone (I-184) were added. Then, while stirring, UV lamp (10 mW) was irradiated to produce a (meth) acrylic polymer A21 having a weight average molecular weight (Mw) of 490,000.

Table 2 shows the ratio of each monomer and each component of the acrylic polymer A21. The abbreviations and the like shown in Table 2 represent the following.

2-EHA: 2-Ethylhexyl Acrylate (Tokyo Chemical Industry Co., Ltd., Japan),
BA: Butyl Acrylate (Tokyo Chemical Industry Co., Ltd., Japan),
2-HEA: 2-Hydroxyethyl acrylate (Tokyo Chemical Industry Co., Ltd., Japan),
LA: Lauryl Acrylate (Tokyo Chemical Industry Co., Ltd., Japan),
I-651: Benzyldimethylketal (photopolymerization initiator, BASF, USA),
I-184: 1-Hydroxycyclohexylphenylketone (photopolymerization initiator, BASF, USA).

(2) Preparation of Adhesive Composition The (meth) acrylic polymer obtained in the above step is 95.5% by mass (solid content conversion value; the same applies hereinafter), and isodecyl acrylate (IDA, Miwon specialty chemical) as an additive. , Korea) 1% by mass and 2-acetoacetoxyethyl methacrylate (AAEM, Sigmaaldrich, USA) 2.5% by mass, and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (TPO, as a photopolymerization initiator) Tokyo Kasei Kogyo Co., Ltd., Japan) 0.5% by mass and 1-hydroxycyclohexylphenylketone (I-184, BASF, USA) 0.5% by mass are mixed, stirred well, and diluted with methyl ethyl ketone. To obtain a coating solution of the pressure-sensitive adhesive composition. Table 3 shows each formulation (solid content conversion value) of the pressure-sensitive adhesive composition. The abbreviations and the like shown in Table 3 represent the following.

IDA: Isodecyl Acrylate (Miwon specialty chemical, South Korea)
AAEM: 2-acetoacetoxyethyl methacrylate (Sigma-Aldrich, USA)
TPO: Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide (Tokyo Chemical Industry Co., Ltd., Japan)
I-184: 1-Hydroxycyclohexylphenyl ketone (BASF, USA)

(3) Production of Adhesive Sheet A21 The coating solution of the obtained pressure-sensitive adhesive composition was applied to the release-treated surface of a light separator (polyethylene terephthalate film, thickness 38 μm) with a knife coater. Next, the coating layer on the system separator obtained above and the heavy separator (polyethylene terephthalate film, thickness 38 μm) are bonded so that the release-treated surface of the separator is in contact with the coating layer, and UV irradiation is performed. Then, a pressure-sensitive adhesive sheet A21 having a pressure-sensitive adhesive layer having a thickness of 25 μm, that is, a pressure-sensitive adhesive sheet A21 having a structure of a light separator / pressure-sensitive adhesive layer (thickness: 25 μm) / heavy separator was produced. The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet A21 is referred to as the pressure-sensitive adhesive layer A21. Table 3 shows the measured shear modulus and gel fraction of the adhesive sheet A21. The thickness, shear modulus, and gel fraction of the pressure-sensitive adhesive layer A21 are values measured by a method described later.

[2] Production of Adhesive Sheets A22 and A23 (1) Preparation of (Meta) Acrylic Polymers A22 and A23 The ratio of each monomer constituting the (Meta) Acrylic Polymer was prepared as shown in Table 2, and the adhesive sheet A21 was prepared. The (meth) acrylic polymers A22 and A23 having a weight average molecular weight (Mw) shown in Table 2 were prepared in the same manner as in the production process of.

(2) Preparation of Adhesive Composition The (meth) acrylic polymer obtained in the above step and the additive are mixed at the blending ratios shown in Table 3, sufficiently stirred, and diluted with methyl ethyl ketone. A coating solution of the pressure-sensitive adhesive composition was obtained.

(3) Production of Adhesive Sheets A22 and A23 Adhesive sheets A22 and A23 were produced in the same manner as in the manufacturing process of the adhesive sheet A21 using the obtained coating solution of the adhesive composition. The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets A22 and A23 are designated as pressure-sensitive adhesive layers A22 and A23. Table 3 shows the thickness, shear modulus, and gel fraction of the pressure-sensitive adhesive layers A22 and A23 measured by the methods described below for the pressure-sensitive adhesive sheets A22 and A23.

<Measurement of weight average molecular weight (Mw)>
The weight average molecular weight (Mw) of the (meth) acrylic polymer was determined by the following size exclusion chromatography (SEC) using tetrahydrofuran as the mobile phase as the polystyrene-equivalent number average molecular weight (Mn).
The (meth) acrylic polymer 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 a 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 layer and the alignment film were measured using a laser microscope (“OLS3000” manufactured by Olympus Corporation).

<Shear modulus>
The shear modulus was measured using a viscoelasticity measuring device (MCR-301, Antonio Par). The same adhesive sheets used in Examples and Comparative Examples were made to have a width of 20 mm and a length of 20 mm, the release film was peeled off, a plurality of sheets were laminated so as to have a thickness of 150 μm, bonded to a glass plate, and then adhered to the measurement chip. The measurement was carried out under the conditions of a frequency of 1.0 Hz, a deformation amount of 1%, and a heating rate of 5 ° C./min in a temperature range of −20 ° C. to 100 ° C., and the shear modulus value at 25 ° C. was confirmed.

<Gel fraction>
The obtained adhesive sheet is cut into a size of 80 mm × 80 mm, the adhesive layer is wrapped in a polyester mesh (mesh size 200), the mass is weighed with a precision balance, and the mass of the mesh alone is subtracted. The mass of the pressure-sensitive adhesive alone was calculated. The mass at this time is M1.

Next, the pressure-sensitive adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23 ° C.) for 24 hours. Then, the adhesive was taken out, air-dried for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and further dried in an oven at 80 ° C. for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. The mass at this time is M2. The gel fraction (%) is represented by (M2 / M1) × 100.

[Front plate (window film)]
As a front plate, a polyimide film (thickness 50 μm) having a hard coat layer (thickness 10 μm) on one side was prepared.

[Polarizer layer]
1. 1. The following materials were prepared.
1) A TAC film with a thickness of 25 μm.

2) Composition for forming an alignment film.
<Polymer 1>
Polymer 1 having a photoreactive group consisting of the following structural units was prepared.

A solution in which polymer 1 was dissolved in cyclopentanone at a concentration of 5% by mass was used as a composition for forming an alignment film [hereinafter, also referred to as composition (D-1)].

3) Composition for forming a polarizer layer <Polymerizable liquid crystal compound>
The polymerizable liquid crystal compound is a polymerizable liquid crystal compound represented by the formula (1-1) [hereinafter, also referred to as compound (1-1)] and a polymerizable liquid crystal compound represented by the formula (1-2) [hereinafter, Also referred to as compound (1-2)].

Compound (1-1) and compound (1-2) are described in Lub et al. Recl. Trav. Chim. It was synthesized by the method described in Pays-Bas, 115, 321-328 (1996).

<Dichroic pigment>
As the dichroic dye, the azo dye described in Examples of Japanese Patent Application Laid-Open No. 2013-101328 represented by the following formulas (2-1a), (2-1b) and (2-3a) was used.

The composition for forming a polarizer layer [hereinafter, also referred to as composition (A-1)] has 75 parts by mass of compound (1-1), 25 parts by mass of compound (1-2), and the above formula as a bicolor dye. 2.5 parts by mass of each of the azo dyes represented by (2-1a), (2-1b) and (2-3a), 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) as a polymerization initiator ) Butan-1-one (Irgacure369, manufactured by BASF Japan) 6 parts by mass, and 1.2 parts by mass of a polyacrylate compound (BYK-361N, manufactured by BYK-Chemie) as a leveling agent, 400 parts by mass of toluene as a solvent. And the resulting mixture was prepared by stirring at 80 ° C. for 1 hour.

4) Composition for forming a protective layer (OC layer) The composition for forming a protective layer (OC layer) [hereinafter, also referred to as composition (E-1)] is water: 100 parts by mass, polyvinyl alcohol resin powder (Co., Ltd.). ) Made by Kuraray, average degree of polymerization 18000, trade name: KL-318): 3 parts by mass, polyamide epoxy resin (crosslinking agent, manufactured by Sumika Chemtex Co., Ltd., trade name: SR650 (30)): 1.5 parts by mass Was prepared by mixing.

2. 2. Production method 1) The composition for forming an alignment film was coated on the TAC film side as follows.
First, the TAC film side was subjected to corona treatment once. The conditions for corona treatment were an output of 0.3 kW and a processing speed of 3 m / min. Then, the composition (D-1) obtained as described above was applied onto the TAC by the bar coating method, and dried by heating in a drying oven at 80 ° C. for 1 minute. The obtained dry film was subjected to polarized UV irradiation treatment to form a first alignment film (AL1). In the polarized UV treatment, the light emitted from the UV irradiation device (SPOT CURE SP-7; manufactured by Ushio, Inc.) is transmitted through a wire grid (UIS-27132 ##, manufactured by Ushio, Inc.) to have a wavelength of 365 nm. The test was performed under the condition that the integrated light amount measured in 1 was 100 mJ / cm ² . The thickness of the first alignment film (AL1) was 100 nm.

2) The composition for forming a polarizer layer was coated on the alignment film side as follows.
First, the composition (A-1) was applied onto the formed first alignment film (AL1) by the bar coating method, heated and dried in a drying oven at 120 ° C. for 1 minute, and then cooled to room temperature. A polarizing layer (pol) was formed by irradiating the dry film with ultraviolet rays at an integrated light amount of 1200 mJ / cm ² (365 nm standard) using the above UV irradiation device. The thickness of the obtained polarizer layer (pol) was measured with a laser microscope (OLS3000 manufactured by Olympus Corporation) and found to be 1.8 μm. In this way, a laminate composed of "TAC / AL1 / pol" was obtained.

3) The composition for forming a protective layer (OC layer) was coated on the polarizer layer side as follows.
The composition (E-1) was applied onto the formed polarizer layer (pol) by a bar coating method, coated so that the thickness after drying was 1.0 μm, and dried at a temperature of 80 ° C. for 3 minutes. .. In this way, a laminate composed of "TAC film / cPL (AL1 + pol + protective layer)" was obtained.

[Phase difference layer]
1. 1. Material preparation The following materials were prepared.
1) PET film with a thickness of 100 μm.

2) Composition for forming an alignment film.
<Polymer 1>
Polymer 1 having a photoreactive group consisting of the following structural units was prepared.

A solution in which polymer 1 was dissolved in cyclopentanone at a concentration of 5% by mass was used as a composition for forming an alignment film [hereinafter, also referred to as composition (D-1)].

3) Composition for forming a retardation layer The composition (B-1) was obtained by mixing each of the following components and stirring the obtained mixture at 80 ° C. for 1 hour.
Compound b-1 represented by the following formula: 80 parts by mass

Compound b-2: 20 parts by mass represented by the following formula

Polymerization initiator (Irgacure369, 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butane-1-one, manufactured by BASF Japan Ltd.): 6 parts by mass leveling agent (BYK-361N, polyacrylate compound, BYK) -Chemie): 0.1 parts by mass Solvent (cyclopentanone): 400 parts by mass

2. 2. Production method 1) The composition for forming an alignment film was coated on the PET film as follows.
A polyethylene terephthalate film (PET) having a thickness of 100 μm was prepared as a base material, the composition (D-1) was applied onto the film by a bar coating method, and the film was heated and dried in a drying oven at 80 ° C. for 1 minute. The obtained dry film was subjected to polarized UV irradiation treatment to form a second alignment film (AL2). The polarized UV treatment was carried out under the condition that the integrated light amount measured at a wavelength of 365 nm was 100 mJ / cm ² using the above UV irradiation device. Further, the polarization direction of the polarized UV was set to 45 ° with respect to the absorption axis of the polarizer layer. In this way, a laminate composed of "base material (PET) / second alignment film (AL2)" was obtained.

2) The composition for forming a retardation layer was coated on the alignment film side of the PET film as follows.
The composition (B-1) is applied by the bar coating method on the second alignment film (AL2) of the first substrate thus obtained, heated and dried in a drying oven at 120 ° C. for 1 minute, and then cooled to room temperature. did. A retardation layer was formed by irradiating the obtained dry film with ultraviolet rays having an integrated light intensity of 1000 mJ / cm ² (365 nm standard) using the above UV irradiation device. The thickness of the obtained retardation layer was measured with a laser microscope (OLS3000 manufactured by Olympus Corporation) and found to be 2.0 μm. The retardation layer was a λ / 4 plate (QWP) showing a retardation value of λ / 4 in the in-plane direction. In this way, a laminate composed of "base material (PET) / AL2 / QWP" was obtained.

[Common adhesive sheet]
1) Polymerization of acrylic resin Acrylic resin was obtained by reacting the following components at 55 ° C. with stirring in a nitrogen atmosphere.
Butyl acrylate: 70 parts by mass Methyl acrylate: 20 parts by mass Acrylic acid: 2.0 parts by mass Radical polymerization initiator (2,2'-azobisisobutyronitrile): 0.2 parts by mass

2) Preparation of adhesive composition The following components were mixed to obtain an adhesive composition.
Acrylic resin: 100 parts by mass Cross-linking agent ("Coronate L" manufactured by Tosoh Corporation): 1.0 parts by mass Silane coupling agent ("X-12-981" manufactured by Shinetsu Silicon Co., Ltd.): 0.5 parts by mass Overall solid Ethyl acetate was added so that the component concentration was 10% by mass to obtain a pressure-sensitive adhesive composition.

3) Manufacture of Adhesive Sheet The release-treated surface of the polyethylene terephthalate film (heavy separator, thickness 38 μm) from which the obtained pressure-sensitive adhesive composition was release-treated so that the thickness after drying using an applicator is 5 μm. Was applied to. The coating layer was dried at 100 ° C. for 1 minute to obtain a film having an adhesive layer. Then, another polyethylene terephthalate film (light separator, thickness 38 μm) that had been released from the mold was attached onto the exposed surface of the pressure-sensitive adhesive layer. Then, it was cured for 7 days under the conditions of a temperature of 23 ° C. and a relative humidity of 50% RH to obtain a light separator / common pressure-sensitive adhesive layer / heavy separator.

[Example 1]
Laminates were manufactured by the procedure shown in FIGS. 4A to 4E. First, the laminate 410 [TAC film 301 / cPL (AL1 + pol) 302 / OC layer 303] including the above-mentioned polarizer layer and the above-mentioned common adhesive sheet 420 (light separator 304 / common adhesive layer 305 / heavy separator 306) Was prepared (Fig. 4 (a)). The OC layer 303 side of the laminate 410 including the polarizer layer and the surface of the common adhesive sheet 420 from which the light separator 304 has been peeled off are subjected to corona treatment (output 0.3 KW, speed 3 m / min) and then bonded. , Laminated body a430 was obtained. The above-mentioned retardation layer 440 [base material (PET) 308 / AL2 / QWP307] was prepared. (Fig. 4 (b)).

Next, the surface where the QWP307 side of the retardation layer 440 and the heavy separator 306 of the laminated body a430 were peeled off was subjected to corona treatment (output 0.3 KW, speed 3 m / min), and then bonded to form the laminated body b450. Obtained. Then, the pressure-sensitive adhesive sheet A11 produced above was prepared as the pressure-sensitive adhesive sheet 460 (light separator 309 / pressure-sensitive adhesive layer 310 / heavy separator 311) (FIG. 4 (c)). The pressure-sensitive adhesive layer 310 of the pressure-sensitive adhesive sheet 460 corresponds to the second pressure-sensitive adhesive layer.

The surface of the laminated body b450 from which the base material (PET) 308 was peeled off and the surface of the adhesive sheet 460 from which the light separator 309 was peeled off were subjected to corona treatment (output 0.3 KW, speed 3 m / min) and then bonded. , Laminated body c470 was obtained. Further, the adhesive sheet A12 produced above was prepared as the adhesive sheet 490 (light separator 314 / adhesive layer 315 / heavy separator 316), and the surface from which the light separator 314 was peeled off and the front plate 480 (polyimide film 313 /) described above were prepared. The polyimide film 313 side of the hard coat layer 312) was subjected to corona treatment (output 0.3 KW, speed 3 m / min) and then bonded to obtain a laminate d500 (FIG. 4 (d)). The pressure-sensitive adhesive layer 315 of the pressure-sensitive adhesive sheet 490 corresponds to the first pressure-sensitive adhesive layer.

The surface of the laminated body d500 from which the heavy separator 316 was peeled off and the TAC301 side of the laminated body c470 were subjected to corona treatment (output 0.3 KW, speed 3 m / min), and then bonded to each other to form the laminated body 300 of Example 1. Obtained (FIG. 4 (e)). The laminated body of Example 1 was evaluated for room temperature flexibility and room temperature adhesive durability by the method described later. The results are shown in Table 4.

[Examples 2 to 6, Comparative Examples 1 and 2]
In Example 1, in the same manner as in Example 1 except that the adhesive sheet having the adhesive layer shown in Table 4 was used instead of using the adhesive sheets A11 and A12, Examples 2 to 6 were compared. The laminates of Examples 1 and 2 were prepared. The laminates of Examples 2 to 6 and Comparative Examples 1 and 2 were evaluated for room temperature flexibility and room temperature adhesive durability by the method described later. The results are shown in Table 4.

<Normal temperature flexibility>
The laminates obtained in each Example and each Comparative Example were subjected to an evaluation test for confirming room temperature flexibility using a bending device (STS-VRT-500, manufactured by Science Town). The heavy separator 311 was peeled off and bonded to a PET film having a thickness of 100 μm to obtain a laminate. The PET film corresponds to the back plate. FIG. 3 is a diagram schematically showing the method of this evaluation test. As shown in FIG. 3, two individually movable mounting tables 501 and 502 are arranged so that the gap C is 6.0 mm (3R) so that the center in the width direction is located at the center of the gap C. The laminated body was fixedly arranged so that the hard coat layer 312 was located on the lower side (FIG. 3 (a)). Then, the two mounting tables 501 and 502 are rotated 90 degrees upward with the position P1 and the position P2 as the center of the rotation axis, and the bending force (front plate 480) is applied to the region of the laminated body corresponding to the gap C of the mounting tables. Bending force on the outside) was added (Fig. 3 (b)). After that, the two mounting tables 501 and 502 were returned to their original positions (FIG. 3 (a)). After completing the above series of operations, the number of times the bending force was applied was counted as one. After repeating this at a temperature of 25 ° C., it was confirmed whether or not bubbles were generated in the pressure-sensitive adhesive layer in the region corresponding to the gap C of the mounting tables 501 and 502 of the laminated body. The moving speed of the mounting tables 501 and 502 and the pace of application of the bending force were set to the same conditions in the evaluation test for all the laminated bodies. "Adhesive removal" means that the adhesive layer protrudes from the end of the laminate.
A: No bubbles were generated even when the number of times the bending force was applied reached 100,000.
B: Bubbles were generated when the number of times the bending force was applied was 50,000 or more and less than 100,000.
C: Bubbles were generated when the number of times the bending force was applied was 20,000 or more and less than 50,000.
D: Bubbles were generated when the number of times the bending force was applied was 10,000 or more and less than 20,000.
E: Bubbles / adhesive loss occurred when the number of times the bending force was applied was less than 10,000.

<Room temperature adhesive durability>
The laminates obtained in each Example and each Comparative Example were cut into a width of 100 mm and a length of 100 mm. The heavy separator 311 was peeled off and bonded to non-alkali glass. It was pressure-bonded in an autoclave (50 ° C., 5 atm) for about 20 minutes and kept under constant temperature and humidity conditions (23 ° C., 50% RH) for 4 hours. The sample was placed in an oven at 25 ° C., and after 250 hours, the presence or absence of floating, peeling, and air bubbles was determined. In the laminated body, the non-alkali glass corresponds to the back plate.
◯: There is almost no change in appearance such as floating, peeling, and foaming.
Δ: Changes in appearance such as floating, peeling, and foaming are slightly noticeable.
X: Appearance changes such as floating, peeling, and foaming are noticeably observed.

Examples 1-6, since satisfies the relation "G _{0 1} ≧ G _{0 2",} the thickness of the first adhesive layer and second adhesive layer are the same, the relationship of "G1 ≧ G2" It can be judged that it satisfies. On the other hand, Comparative Examples 1 and 2 have a relationship of "G ₀ 1 <G ₀₂ ", and since the thicknesses of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are the same, "G 1 <G 2" It can be judged that it is a relationship.

100,200 laminate, 101 front plate, 102 first pressure-sensitive adhesive layer, 103 polarizer layer, 104 second pressure-sensitive adhesive layer, 105 back plate, 106 first retardation layer, 107 second retardation layer, 108, 109 Laminated layer, 501,502 stages.

Claims (6)

The front plate, the first pressure-sensitive adhesive layer formed by using the first pressure-sensitive adhesive composition, the polarizer layer, the second pressure-sensitive adhesive layer formed by using the second pressure-sensitive adhesive composition, and the back plate. , In this order,
Assuming that the shear modulus of the first pressure-sensitive adhesive layer at a temperature of 25 ° C. is G1 [Pa] and the shear modulus of the second pressure-sensitive adhesive layer at a temperature of 25 ° C. is G2 [Pa], the following relational expression (1) ):
G1 ≧ G2 (1)
The filling,
The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are laminates having a gel fraction of 45% or more and 85% or less. The first pressure-sensitive adhesive composition and the second pressure-sensitive adhesive composition both contain a (meth) acrylic polymer.
The laminate according to claim 1, wherein the (meth) acrylic polymer has a structural unit derived from a monomer having a reactive functional group of less than 5% by mass based on the total mass. The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer both contain a (meth) acrylic polymer.
The laminate according to claim 1 or 2, wherein the (meth) acrylic polymer has a weight average molecular weight (Mw) of 200,000 or more and 1.5 million or less. The laminate according to any one of claims 1 to 3, wherein the back plate is a touch sensor panel. A display device including the laminate according to any one of claims 1 to 4. The display device according to claim 5, which is bendable with the front plate side facing outward.

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