TW202031477A - Laminate and display device - Google Patents

Abstract

An objective of the present invention is to provide a laminate that has excellent adhesive force and suppresses the generation of air bubbles even after bending with the front plate side facing inwards. The present invention provides a laminate comprising, in the following order, a front plate, a first adhesive layer formed using a first adhesive composition, a polarizer layer, a second adhesive layer formed using a second adhesive composition, and a back plate. If R1 is the shear stress relaxation ratio of the first adhesive layer at a temperature of 25 DEG C and R2 is the shear stress relaxation ratio of the second adhesive layer at a temperature of 25 DEG C, relational expression (1): R1 ≥ R2 is satisfied.

Description

Laminated body and display device

The present invention relates to a laminated body and a display device using the laminated body.

Japanese Patent Application Laid-Open No. 2018-28573 (Patent Document 1) describes a laminate for a flexible image display device having a plurality of adhesive layers. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2018-28573

[The problem to be solved by the invention]

In a display device including a laminate having a front surface plate and a plurality of adhesive layers, when the front surface plate side is repeatedly bent on the outside, the adhesive layer in the laminate may generate bubbles. In addition, the adhesive force of the adhesive layer is weak, which may cause floating or peeling between the adhesive layer and the adhered member.

An object of the present invention is to provide a laminate that can suppress the generation of air bubbles and is excellent in adhesive force even when the front surface plate side is repeatedly curved on the outside, and a display device using the laminate. [Means to solve the problem]

The present invention provides the following laminate and display device. [1] A laminated body comprising in order: a front surface plate; a first adhesive layer formed using a first adhesive composition; a polarizer layer; a second adhesive layer formed using a second adhesive composition; and For the back panel, if the shear stress relaxation rate at the temperature of the first adhesive layer at 25°C is R1, and the shear stress relaxation rate at the temperature of the second adhesive layer at 25°C is set to R2, Then the following relationship (1) is satisfied: R1≧R2 (1). [2] The layered product according to [1], wherein the shear stress relaxation rate at a temperature of 25°C of a first reference adhesive layer with a thickness of 150 μm formed using the first adhesive composition is R ₀ 1. If the shear stress relaxation rate at a temperature of 25°C of a second reference adhesive layer with a thickness of 150 μm formed using the second adhesive composition is R ₀ 2, the following relationship is satisfied ( 2) and relational expression (3): 0.02≦R ₀ 1≦0.25 (2) 0.02≦R ₀ 2≦0.25 (3). [3] The laminate according to [1] or [2], wherein the first adhesive composition and the second adhesive composition both contain a (meth)acrylic polymer. [4] The laminate according to [3], wherein the weight average molecular weight (Mw) of the (meth)acrylic polymer is 200,000 or more and 1.5 million or less. [5] The laminate as described in [3] or [4], wherein the (meth)acrylic polymer is derived from a monomer having a reactive functional group based on the total mass of the polymer The constituent unit is less than 5 mass%. [6] The laminate according to any one of [1] to [5], wherein the back panel is a touch sensor panel. [7] A display device comprising the laminate according to any one of [1] to [6]. [8] The display device according to [7], which can bend the front panel side outward. [Effects of the invention]

According to the present invention, it is possible to provide a laminate that can suppress the generation of air bubbles and is excellent in adhesive force even when the front surface plate side is repeatedly curved to the outside, and a display device using the laminate.

Hereinafter, a laminate according to an embodiment of the present invention (hereinafter also simply referred to as "laminate") will be described with reference to the drawings.

＜Laminated body＞ FIG. 1 shows a schematic cross-sectional view of a laminate (optical laminate) according to an embodiment of the present invention. The laminate 100 includes a front surface plate 101, a first adhesive layer 102, a polarizer layer 103, a second adhesive layer 104 and a back plate 105 in sequence. The first adhesive layer 102 is formed of a first adhesive composition, and the second adhesive layer 104 is formed of a second adhesive composition. Hereinafter, the first adhesive layer 102 and the second adhesive layer 104 may be collectively referred to as an adhesive layer.

The thickness of the layered body 100 varies depending on the functions required for the layered body and the purpose of the layered body, and therefore is not particularly limited. For example, it is 50 μm or more and 4000 μm or less, preferably 100 μm or more and 2000 μm or less, and more It is preferably 150 μm or more and 1000 μm or less.

The planar shape of the laminate 100 may be, for example, a square shape, preferably a square shape having long sides and short sides, and more preferably a rectangular shape. When the shape of the laminate 100 in the plane direction is a rectangle, the length of the long side may be, for example, 10 mm or more and 1400 mm or less, and 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 layered body may be R processed at the corners, cut at the ends, or drilled.

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 organic electroluminescence (organic electroluminescence, organic EL) display devices, inorganic electroluminescence (inorganic EL) display devices, liquid crystal display devices, electroluminescence display devices, and the like. The display device may have a touch panel function.

[Shear stress relaxation rate of adhesive layer] In the laminate 100, if the shear stress relaxation rate at the temperature of the first adhesive layer 102 at 25°C is R1, and the shear stress relaxation rate at the temperature of the second adhesive layer 104 at 25°C is set to R2, Then the following relationship (1) is satisfied: R1≧R2 (1), It is more preferable to satisfy the following relational expression (1'): R1>R2 (1'). Regarding whether the relationship (1) is satisfied, the relationship (1’) is i) The method of judgment based on the values of R1 and R2; and ii) A method of judging based on other combinations that have the same magnitude relationship as the combination of R1 and R2.

Although the shear stress relaxation rate has nothing to do with the thickness of the adhesive layer, when the first adhesive layer 102 and the second adhesive layer 104 are too thin, it is sometimes difficult to accurately measure the shear stress relaxation rate. As one of the judgment methods based on the other combination of ii), for example, a first reference adhesive layer formed of a first adhesive composition and a second reference adhesive formed of a second adhesive composition can be cited The method of layer comparison. The shear stress relaxation rate R ₀ 1 at the temperature of the first reference adhesive layer at 25° C. and the shear stress relaxation rate R ₀ 2 at the temperature of the second reference adhesive layer at 25° C. satisfy the following relationship (1a ): In the case of R ₀ 1≧R ₀ 2 (1a), it can be regarded as satisfying the relational expression (1), which satisfies the following relational expression (1'a): R ₀ 1>R ₀ 2 (1'a) In this case, it can be regarded as satisfying the relationship (1'). The thickness of the first reference adhesive layer and the second reference adhesive layer may be 150 μm. The shear stress relaxation rate R ₀ 1 and R ₀ 2 of the first reference adhesive layer and the second reference adhesive layer with a thickness of 150 μm at a temperature of 25° C. were measured in accordance with the measurement method described in the column of Examples described later.

The laminate 100 can be bent with the front surface plate 101 side on the outside. For a display device including a laminate, if the front surface plate side is repeatedly bent on the outside, air bubbles may be generated in the adhesive layer. The generation of the air bubbles is particularly remarkable in the adhesive layer on the side away from the front surface plate, that is, the second adhesive layer 104 in the laminate 100. As a result of research conducted by the present inventors, it was found that when the shear stress relaxation rate of the first adhesive layer 102 and the second adhesive layer 104 satisfies the relational expression (1), even if the front surface plate 101 side is made to be curved repeatedly on the outside It is also possible to suppress bubbles generated in the adhesive layer in the laminate 100. More specifically, even if the inner surface of the layered body 100 is repeatedly bent 20,000 times with a bending radius of 3 mm, the bubbles generated in the adhesive layer in the layered body 100 (hereinafter also referred to as having excellent "Normal temperature flexibility"). The room temperature bendability can be evaluated in accordance with the evaluation method described in the column of Examples described later. The laminated body 100 can also be bent with the front panel side as the inner side. The display device to which the laminate 100 is applied can be used as a flexible display that can be bent, wound, or the like.

In this specification, bending includes a bending form in which a curved surface is formed in a bending portion, and the bending radius of the inner surface of the bending is not particularly limited. In addition, bending also includes bends where the bending angle of the inner surface is greater than 0 degrees and less than 180 degrees, and the bending radius of the inner surface is approximately zero or the bending angle of the inner surface is 0 degrees.

In addition, when the shear stress relaxation rate of the first adhesive layer 102 and the second adhesive layer 104 satisfies the relationship (1), even if it is left standing for a long time under constant temperature and humidity conditions, the adhesive layer and the substrate There are also almost no appearance changes such as floating, peeling, and foaming between the adhesive members, and it can be seen that the adhesive durability at room temperature is excellent. The room temperature adhesion durability can be evaluated in accordance with the evaluation method described in the column of Examples described later.

If the shear stress relaxation rate of the first reference adhesive layer with a thickness of 150 μm at 25°C is set to R ₀ 1, and the shear stress at the temperature of the second reference adhesive layer with a thickness of 150 μm at 25°C The relaxation rate is set to R ₀ 2, and it is preferable to satisfy the following relational expression (2) and relational expression (3): 0.02≦R ₀ 1≦0.25 (2) 0.02≦R ₀ 2≦0.25 (3), more preferably To satisfy the following relational expression (2a) and relational expression (3a): 0.10≦R ₀ 1≦0.20 (2a) 0.10≦R ₀ 2≦0.20 (3a).

As a method of preparing the first adhesive composition and the second adhesive composition in such a way that the shear stress relaxation rates of the first adhesive layer 102 and the second adhesive layer 104 satisfy the relational formula (1), for example: The method of forming an adhesive layer from the adhesive composition A mentioned later, or changing the kind of monomer which comprises (meth)acrylic-type polymer A mentioned later, or adjusting the molecular weight of (meth)acrylic-type polymer A, etc. are mentioned later.

[Adhesive composition] In one aspect, the first adhesive layer 102 and the second adhesive layer 104 are formed of an adhesive composition containing a (meth)acrylic polymer (hereinafter also referred to as an adhesive composition A). The adhesive composition A may be an active energy ray hardening type or a thermosetting type. In addition, the "(meth)acrylic polymer" in this specification means at least one selected from the group consisting of acrylic polymers and methacrylic polymers. The same applies to other terms with "(methyl)".

(1) Active energy ray hardening adhesive composition When the adhesive composition A is an active energy ray curable adhesive composition, the (meth)acrylic polymer contained in the adhesive composition A (hereinafter also referred to as (meth)acrylic polymer) A) A structural unit derived from a (meth)acrylic monomer may be contained, and the (meth)acrylic monomer may be linear, branched, or cyclic. As a (meth)acrylic-type monomer, (meth)acrylate, (meth)acrylamide etc. are mentioned, for example. Examples of (meth)acrylates include butyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, hexyl (meth)acrylate, and (meth)acrylic acid Octyl ester, lauryl (meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, hydroxypropyl (meth)acrylate, Tetrahydrofurfuryl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, etc. Examples of (meth)acrylamides include (meth)acrylamides, N,N-dimethyl(meth)acrylamides, and N,N-diethyl(meth)acrylamides , N-isopropyl(meth)acrylamide, N-methoxyethyl(meth)acrylamide, N,N-propyl(meth)acrylamide, N-ethacrylamide , N-(2-hydroxyethyl)(meth)acrylamide, etc. The (meth)acrylic polymer A may be a polymer or copolymer in which one or two or more selected from the above-mentioned (meth)acrylate and (meth)acrylamide are used as monomers. The content of the (meth)acrylic polymer A in the adhesive composition A can be, for example, 50% by mass or more and 100% by mass or less, and preferably 80% by mass relative to 100% by mass of the solid content of the adhesive composition A % Or more and 99.5% by mass or less, more preferably 88% by mass or more and 99% by mass or less, and still more preferably 90% by mass or more and 99% by mass or less.

（式（I）中，Z¹ 為氧原子或氮原子，Z² 為氧原子、氮原子或碳原子，Y為烴基）。 式（I）中，Y可為環狀的烴基，亦可為Y與Z¹ 或Z² 的任一者一起構成環。Z¹ 或Z² 可為鍵結於(甲基)丙烯醯基的氧原子或氮原子。就提高耐久性的觀點而言，Y較佳為碳原子數為1以上且10以下，更佳為1以上且5以下。The (meth)acrylic polymer contained in the adhesive composition A is preferably a (meth)acrylic polymer containing a structural unit derived from (meth)acrylate or (former) A monomer containing amide acrylate and a structure represented by the following formula (I): [化1]

(In formula (I), Z ¹ is an oxygen atom or a nitrogen atom, Z ² is an oxygen atom, a nitrogen atom or a carbon atom, and Y is a hydrocarbon group). In formula (I), Y may be a cyclic hydrocarbon group, or Y and either Z ¹ or Z ² may form a ring together. Z ¹ or Z ² may be an oxygen atom or a nitrogen atom bonded to a (meth)acryloyl group. From the viewpoint of improving durability, Y preferably has a carbon number of 1 or more and 10 or less, and more preferably 1 or more and 5 or less.

Preferably, at least one of the (meth)acrylic polymer A contained in the first adhesive composition and the second adhesive composition contains a structure derived from the structure represented by formula (I) and is (methyl) ) A structural unit of a monomer of acrylic acid ester or (meth)acrylamide. With the adhesive composition A containing such a (meth)acrylic polymer, the first reference adhesive layer and the second reference adhesive that satisfy the relational expressions (2) and (3) can be easily formed Agent layer. In the (meth)acrylic polymer A, relative to 100% by mass of the solid content of the (meth)acrylic polymer A, it may contain, for example, 1% by mass or more and 20% by mass or less, preferably 2% by mass or more, and 10% by mass or less of a structural unit derived from a monomer containing the structure represented by formula (I) and being a (meth)acrylate or (meth)acrylamide.

As a monomer which is (meth)acrylate or (meth)acrylamide and contains the structure represented by formula (I), for example, the following compound formula (II)-compound formula (VI) represented by ( Meth) acrylic monomer.

（式中，R表示氫原子或甲基）

(In the formula, R represents a hydrogen atom or a methyl group)

In the (meth)acrylic polymer A, in addition to the structural unit derived from the monomer containing the structure represented by the formula (I) and which is a (meth)acrylate or (meth)acrylamide, the polymer Based on the total mass of, the constituent unit derived from a monomer having a reactive functional group is preferably less than 5% by mass. Examples of the reactive functional group include a hydroxyl group, a carboxyl group, an amino group, an amide group, and an epoxy group. Thereby, the flexibility of the adhesive layer is improved, and there is a tendency that bubbles are not easily generated when bent. From the viewpoint of preventing the generation of bubbles, the (meth)acrylic polymer A is preferably based on the total mass of the polymer, and the constituent unit derived from a monomer having a reactive functional group may be 1% by mass or less, It is more preferably 0.01% by mass or less, still more preferably not having a structural unit derived from a monomer having a reactive functional group, and still more preferably not having a hydroxyl group, a carboxyl group, an amino group, an amide group, and an epoxy group.

The weight average molecular weight (Mw) of the (meth)acrylic polymer A may be, for example, 300,000 or more and 700,000 or less, and from the viewpoint of suppressing bubbles during bending, it is preferably 300,000 or more and 600,000 or less. The weight average molecular weight (Mw) can be measured in accordance with the measurement method described in the column of Examples described later.

The adhesive composition A may contain one or two or more (meth)acrylic polymers A. In addition, the adhesive composition A may contain only the (meth)acrylic polymer A as its constituent component, or may further contain a crosslinking agent. Examples of the crosslinking agent include: a metal ion having a valence of two or more and forming a metal carboxylic acid salt with a carboxyl group; a polyamine compound forming an amide bond with a carboxyl group; a polyepoxy compound or Polyols and those that form ester bonds with carboxyl groups; those that are polyisocyanate compounds and those that form amide bonds with carboxyl groups. Among them, polyisocyanate compounds are preferred. When the adhesive composition A contains a crosslinking agent, the content of the crosslinking agent may be, for example, 5 parts by mass or less, preferably 1 part by mass or less, relative to 100 parts by mass of the (meth)acrylic polymer A , More preferably 0.5 parts by mass or less, and still more preferably 0.1 parts by mass or less, the adhesive composition A most preferably does not contain a crosslinking agent.

The so-called active energy ray curable adhesive composition means that it has the property of being cured by irradiation of active energy rays such as ultraviolet rays or electron rays, and has adhesiveness even before the active energy rays are irradiated, so that it can bond with the film. Adhesive composition that can adjust the properties of adhesion and other properties such as the adhesion of the adherend and hardening by irradiation of active energy rays.

The active energy ray curable adhesive composition is preferably an ultraviolet curable adhesive composition.

When the adhesive composition A is an active energy ray curable adhesive composition, the adhesive composition A may further contain an active energy ray polymerizable compound, a photopolymerization initiator, or a photosensitizer.

As the active energy ray polymerizable compound, for example, a (meth)acrylate monomer having at least one (meth)acryloyloxy group in the molecule; obtained by reacting two or more functional group-containing compounds, and (Meth)acrylic compounds such as (meth)acryloxy group-containing compounds such as (meth)acrylate oligomers having at least two (meth)acryloxy groups. With respect to 100 parts by mass of the solid content of the adhesive composition A, the adhesive composition A may contain 0.1 parts by mass or more and 10 parts by mass or less of the active energy ray polymerizable compound.

As a photopolymerization initiator, benzophenone, benzil dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, etc. are mentioned, for example. When the adhesive composition A contains a photopolymerization initiator, it may contain one kind or two or more kinds. When the adhesive composition A contains a photopolymerization initiator, the total content thereof may be 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 adhesive composition A, for example.

The adhesive composition A may contain fine particles, beads (resin beads, glass beads, etc.), glass fibers, resins other than raw polymers, adhesiveness imparting agents, fillers (metal powder or other inorganic powders) for imparting light scattering properties Etc.), antioxidants, ultraviolet absorbers, dyes, pigments, colorants, defoamers, anti-corrosion agents and other additives. From the viewpoint of preventing the problem of durability reduction caused by the residual solvent, the adhesive composition A preferably does not contain an organic solvent.

When the adhesive layer is formed of the adhesive composition A, the adhesive layer can be formed by coating the adhesive composition A on the substrate. In the case of using an active energy ray-curable adhesive composition, the formed adhesive layer can be irradiated with active energy rays to produce a cured product having a desired degree of curing.

The adhesive composition A can be produced by mixing the components together using a known method, for example, using a mixer.

(2) Thermosetting adhesive composition When the adhesive composition A is a thermosetting adhesive composition, the (meth)acrylic polymer A is preferably an alkyl (meth)acrylate having 2 to 20 carbon atoms, And a monomer having a reactive functional group in the molecule (a monomer containing a reactive functional group) is used as a monomer unit constituting the polymer.

The (meth)acrylic polymer A has an alkyl (meth)acrylic acid alkyl ester having 2 to 20 carbon atoms as a monomer unit constituting the polymer, and can exhibit better adhesiveness. The alkyl (meth)acrylate having a carbon number of 2-20 as the alkyl group is preferably a homopolymer having a glass transition temperature (Tg) of -40°C or less (hereinafter sometimes referred to as "low Tg acrylic acid Alkyl ester"). By containing the low Tg alkyl acrylate as a constituent monomer unit, the flexibility of the adhesive layer is improved, floating or peeling is less likely to occur between the adhesive layer and the adhered member, and the front surface plate side is the outer side In the case of repeated bending, there is a tendency to easily suppress the generation of air bubbles in the adhesive layer.

As the low Tg alkyl acrylate, for example, n-butyl acrylate (Tg is -55°C), n-octyl acrylate (Tg is -65°C), and isooctyl acrylate (Tg is -58°C) , 2-ethylhexyl acrylate (Tg is -70℃), isononyl acrylate (Tg is -58℃), isodecyl acrylate (Tg is -60℃), isodecyl methacrylate (Tg is- 41℃), n-lauryl methacrylate (Tg is -65℃), tridecyl acrylate (Tg is -55℃), tridecyl methacrylate (Tg is -40℃), etc. Among them, from the viewpoint that the shear stress relaxation rate of the resulting adhesive at a temperature of 25°C easily falls into the above-mentioned range, the low-Tg alkyl acrylate is more preferably one with a homopolymer Tg of -45°C or less , Particularly preferably those below -50°C. Specifically, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferred. These can be used alone or in combination of two or more.

In the (meth)acrylic polymer A, as the monomer unit constituting the polymer, the following limit is preferably 85% by mass or more of low Tg alkyl acrylate, more preferably 90% by mass or more, and further It is preferable to contain 95% by mass or more. If it is this range, the shear stress relaxation rate at the temperature of 25 degreeC of the adhesive agent obtained will easily fall into the said range.

In addition, in the (meth)acrylic polymer A, as a monomer unit constituting the polymer, it is preferable that the above limit contains the low Tg alkyl acrylate in an amount of 99.9% by mass or less, and more preferably 99.5 mass% % Or less, more preferably 99% by mass or less. By containing 99.9% by mass or less of the low Tg alkyl acrylate, an appropriate amount of other monomer components (especially monomers containing reactive functional groups) can be introduced into the (meth)acrylic polymer A.

In order to easily set the glass transition temperature (Tg) of the main polymer of the adhesive of the present embodiment within the above range, the (meth)acrylic polymer A is preferably as low as possible as the homopolymer glass transition temperature ( Tg) The content of monomers exceeding 0°C (hereinafter sometimes referred to as "hard monomers"). Specifically, in the (meth)acrylic polymer A, as a monomer unit constituting the polymer, the content of the hard monomer is preferably set to 15% by mass or less, more preferably 10 Mass% or less, more preferably 5 mass% or less. In addition, the hard monomer also includes the reactive functional group-containing monomer described later.

As the hard monomer, for example, methyl acrylate (Tg is 10°C), methyl methacrylate (Tg is 105°C), ethyl methacrylate (Tg is 65°C), n-butyl methacrylate Esters (Tg is 20°C), isobutyl methacrylate (Tg is 48°C), tertiary butyl methacrylate (Tg is 107°C), n-stearyl acrylate (Tg is 30°C), methacrylic acid Stearyl ester (Tg is 38°C), cyclohexyl acrylate (Tg is 15°C), cyclohexyl methacrylate (Tg is 66°C), phenoxyethyl acrylate (Tg is 5°C), methyl Phenoxyethyl acrylate (Tg is 54°C), benzyl methacrylate (Tg is 54°C), isobornyl acrylate (Tg is 94°C), isobornyl methacrylate (Tg is 180°C), acrylic Acrylic morpholine (Tg of 145°C), adamantyl acrylate (Tg of 115°C), adamantyl methacrylate (Tg of 141°C), acrylic acid (Tg of 103°C), dimethyl acrylate Acrylic monomers such as amine (Tg: 89°C), acrylamide (Tg: 165°C), vinyl acetate (Tg: 32°C), styrene (Tg: 80°C), etc.

The (meth)acrylic polymer A contains a reactive functional group-containing monomer as a monomer unit constituting the polymer, and passes through the reactive functional group derived from the reactive functional group-containing monomer to be described later The thermal crosslinking agent reacts to form a crosslinked structure (three-dimensional network structure) to obtain an adhesive with the desired cohesive force.

Examples of the reactive functional group-containing monomer contained in the (meth)acrylic polymer A as a monomer unit constituting the polymer include: monomers having a hydroxyl group in the molecule (a hydroxyl group-containing monomer Monomers), monomers having carboxyl groups in the molecule (carboxyl group-containing monomers), monomers having amine groups in the molecule (amine group-containing monomers), etc. Among these, in many cases where the glass transition temperature (Tg) is 0°C or less, a hydroxyl group-containing monomer is particularly preferred.

Examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2 (meth)acrylic acid. -Hydroxyalkyl (meth)acrylates such as hydroxybutyl, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. Among them, in terms of the glass transition temperature (Tg), the reactivity of the hydroxyl group in the obtained (meth)acrylic polymer A with the thermal crosslinking agent, and the copolymerizability with other monomers, it is preferably At least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, and 4-hydroxybutyl acrylate. These can be used alone or in combination of two or more.

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

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

In the (meth)acrylic polymer A, as the monomer unit constituting the polymer, the following limit is preferably 0.1% by mass or more of the reactive functional group-containing monomer, particularly preferably 0.5% by mass or more , It is more preferable to contain 1% by mass or more. In addition, the above limit is preferably 10% by mass or less, particularly preferably 8% by mass or less, more preferably 5% by mass or less, and most preferably less than 5% by mass. If the (meth)acrylic polymer A contains a reactive functional group-containing monomer, especially a hydroxyl-containing monomer, as a monomer unit in the stated amount, the temperature of the resulting adhesive layer is sheared at 25°C The stress relaxation rate easily enters the range.

The (meth)acrylic polymer A may not contain a carboxyl group-containing monomer, particularly acrylic acid which is also a hard monomer, as a monomer unit constituting the polymer. The carboxyl group is an acid component. Therefore, by not containing a carboxyl group-containing monomer, even if there is a problem caused by acid in the object of the adhesive, such as tin-doped indium oxide (indium tin oxide, ITO )) etc. In the case of transparent conductive films, metal films, metal meshes, etc., these disadvantages (corrosion, resistance value changes, etc.) due to acid can also be suppressed.

The (meth)acrylic polymer A may also contain other monomers as monomer units constituting the polymer as necessary. As other monomers, in order not to interfere with the function of the reactive functional group-containing monomer, it is also preferable that the monomer does not contain a reactive functional group. As the other monomers, for example, in addition to alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, homopolymers may be mentioned. A monomer whose glass transition temperature (Tg) exceeds -40°C and is below 0°C (hereinafter sometimes referred to as "medium Tg alkyl acrylate" and the like. As medium Tg alkyl acrylate, for example, ethyl acrylate (Tg -20°C), isobutyl acrylate (Tg is -26°C), 2-ethylhexyl methacrylate (Tg is -10°C), n-lauryl acrylate (Tg is -23°C), iso-hard acrylic acid Fatty ester (Tg is -18°C), etc. These can be used alone or in combination of two or more.

The polymerization state of (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 still more preferably 400,000 or more. If the lower limit of the weight average molecular weight of the (meth)acrylic polymer A is more than the above, it is possible to suppress defects such as leaching of the adhesive. In addition, the weight average molecular weight in this specification is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method.

In addition, 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 still more preferably 1.2 million or less. If the upper limit value of the weight average molecular weight of the (meth)acrylate polymer A is the above-mentioned or less, the shear stress relaxation rate at the temperature of 25 degreeC of the adhesive bond layer obtained will easily fall into the said range.

In addition, in the adhesive composition A, the (meth)acrylic polymer A may be used alone or in combination of two or more.

When the adhesive composition A containing the thermal crosslinking agent is heated, the thermal crosslinking agent crosslinks the (meth)acrylic polymer A to form a three-dimensional network structure. Thereby, the cohesive force of the obtained adhesive improves, and the shear stress relaxation rate at the temperature of 25 degreeC of the obtained adhesive layer easily falls into the said range.

The thermal crosslinking agent may be one that reacts with the reactive group possessed by the (meth)acrylic polymer A, and examples thereof include isocyanate crosslinking agents, epoxy crosslinking agents, and amine crosslinking agents. Linking agent, melamine-based cross-linking agent, 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 Crosslinking agent, metal salt crosslinking agent, ammonium salt crosslinking agent, etc. Among the above, when the reactive group possessed by the (meth)acrylic polymer A is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent having excellent reactivity with the hydroxyl group. Furthermore, the thermal crosslinking agent may be used alone or in combination of two or more.

The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; isophorone diisocyanate, Hydrogenated diphenylmethane diisocyanate and other alicyclic polyisocyanates, etc.; and these biuret bodies, isocyanurate bodies, and as a combination with ethylene glycol, propylene glycol, neopentyl glycol, and trimethylolpropane , Castor oil and other adducts of the reaction products of compounds containing low molecular active hydrogen. Among them, from the viewpoint of reactivity with hydroxyl groups, aromatic polyisocyanates modified with trimethylolpropane are preferred, and toluene diisocyanate modified with trimethylolpropane and trimethylolpropane modified are particularly preferred. Xylylene diisocyanate.

As an epoxy-based crosslinking agent, for example, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl- M-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine, etc.

Relative to 100% by mass of the (meth)acrylic polymer A, the content of the thermal crosslinking agent in the adhesive composition A is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.1% by mass %the above. In addition, the content is preferably 1% by mass or less, more preferably 0.8% by mass or less, and still more preferably 0.5% by mass or less. When the content of the thermal crosslinking agent is in the above range, the shear stress relaxation rate of the resulting adhesive layer at a temperature of 25° C. easily enters the above range.

The adhesive composition A preferably contains a silane coupling agent. Thereby, the adhesiveness of the obtained adhesive bond layer and each member in the laminated body which is an adherend improves, and the durability to bending becomes more excellent.

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

Examples of the silane coupling agent include: vinyl trimethoxy silane, vinyl triethoxy silane, methacryloxypropyl trimethoxy silane, and other polymerizable unsaturated group-containing silicon compounds; 3-condensation Silicon compounds with epoxy structure such as glyceroxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc.; 3-mercaptopropyltrimethoxysilane, 3-mercapto Sulfhydryl-containing silicon compounds such as propyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, etc.; 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3 -Aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane and other amino-containing silicon compounds; 3-chloropropyltrimethoxy Silane, 3-isocyanate propyltriethoxysilane, or at least one of these and methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, etc. Condensates of alkyl-containing silicon compounds, etc. These can be used alone or in combination of two or more.

Relative to 100% by mass of the (meth)acrylic polymer A, the content of the silane coupling agent in the adhesive composition A is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.1% by mass the above. In addition, the content is preferably 1% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.3% by mass or less. When the content of the silane coupling agent is in the above-mentioned range, the resulting adhesive layer has better adhesion to each member in the laminate as the adherend.

In the adhesive composition A, various additives may be added as necessary. In addition, the polymerization solvent or the dilution solvent is regarded as not being included in the additives constituting the adhesive composition A.

The (meth)acrylic polymer A can be produced by polymerizing a mixture of monomers constituting the polymer by a normal radical polymerization method. The polymerization of the (meth)acrylic polymer A is preferably carried out by a solution polymerization method using a polymerization initiator as necessary. As a polymerization solvent, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, etc. are mentioned, for example, You may use 2 or more types together.

Examples of the polymerization initiator include azo compounds, organic peroxides, and the like, and two or more of them may be used in combination. As the azo compound, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane 1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxypentane) Nitrile), 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 organic peroxides include: benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, peroxy Di(2-ethoxyethyl) oxydicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxyvalerate, peroxide (3,5,5-trimethylhexyl) , Dipropylene peroxide, diacetyl peroxide, etc.

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

After obtaining the (meth)acrylic polymer A, add a thermal crosslinking agent, a silane coupling agent, and additives and diluent solvents as necessary to the solution of the (meth)acrylic polymer A, and mix them thoroughly, thereby The adhesive composition A (coating solution) diluted with a solvent is obtained.

In addition, in any of the above-mentioned components, when a solid one is used, or when precipitation occurs when mixed with other components in an undiluted state, the component may be separately dissolved in advance Or diluted in dilute solvent, and then mixed with other ingredients.

As the diluent solvent, for example, aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane and dichloroethane; methanol, ethanol, and propylene Alcohol, butanol, 1-methoxy-2-propanol and other alcohols; acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone and other ketones; ethyl acetate, butyl acetate, etc. Esters; Ethyl siloxu and other siloxus-based solvents.

The concentration and viscosity of the coating solution prepared in this way are not particularly limited as long as they are in a range that can be coated, and can be appropriately selected according to the situation. For example, dilution is performed so that the concentration of the adhesive composition A is 10% by mass to 60% by mass. In addition, when obtaining a coating solution, the addition of a dilution solvent etc. is not an essential condition, and if the adhesive composition A has the viscosity etc. which can apply|coat, the dilution solvent may not be added. In this case, the adhesive composition A becomes a coating solution in which the polymerization solvent of the (meth)acrylic polymer A is directly used as a diluting solvent.

The adhesive agent preferable as the adhesive agent of this embodiment is what crosslinked the adhesive agent composition A. The crosslinking of the adhesive composition A can be performed by heat treatment. In addition, this heat treatment can also be used as a drying treatment at the time of volatilizing the coating film of the adhesive composition A obtained by applying a dilution solvent or the like to a desired object.

The heating temperature of the heat treatment is preferably 50°C to 150°C, more preferably 70°C to 120°C. In addition, 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 set at normal temperature (for example, 23° C., 50% RH). In the case where the curing period is required, the adhesive is formed after the curing period has passed, and in the case where the curing period is not required, the adhesive is formed after the heat treatment is completed.

Through the heat treatment (and curing), the (meth)acrylic polymer A is sufficiently crosslinked via a crosslinking agent to form a crosslinked structure, and an adhesive is obtained. The shear stress relaxation rate of the adhesive layer formed of this adhesive at a temperature of 25° C. easily enters the above range.

The adhesive sheet of the present invention includes an adhesive layer formed of the adhesive composition A of the present invention. The adhesive layer can be formed by coating the adhesive composition A on the substrate. In the case of using a thermosetting adhesive composition as the adhesive composition A, the formed adhesive layer can be heated (and cured) to produce a cured product having a desired degree of curing. In addition, the heat treatment and curing conditions are as described above.

The substrate may be a release film that has been subjected to mold release treatment. The adhesive sheet can be produced by pre-forming a layer containing an adhesive on the release film into a sheet shape, and then attaching another release film on the adhesive layer.

As a method of applying the coating liquid of the adhesive composition A, for example, a bar coating method, a knife coating method, a roll coating method, a knife coating method, a die coating method, a gravure coating method, etc. can be used.

[Front Panel] As long as the front surface plate 101 is a plate-shaped body capable of transmitting light, the material and thickness are not limited, and may include only one layer, or two or more layers. As an example, a resin plate-shaped body (for example, a resin plate, a resin sheet, a resin film, etc.), a glass plate-shaped body (for example, a glass plate, a glass film, etc.), and the touch sensor panel mentioned later can be mentioned. The front surface plate may be the most surface of the display device.

The thickness of the front surface plate 101 may be, for example, 10 μm or more and 500 μm or less, preferably 30 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 in accordance with the thickness measurement method described in the examples described later.

In the case where the front surface plate 101 is a plate-shaped body made of resin, the plate-shaped body made of resin is not limited as long as it can transmit light. Examples of the resin constituting the plate-shaped body made of resin such as resin film include triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, acryl-based cellulose, butyl-based cellulose, Acetyl propylene cellulose, polyester, polystyrene, polyamide, polyetherimide, poly(meth)acrylic acid, polyimide, polyether chrysene, poly chrysene, polyethylene, polypropylene , Polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polyether ash, polymethyl methacrylate, polyterephthalate Films formed of polymers such as ethylene formate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, and polyamide imide. 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, polyimide, and polyimide is preferred.

From the viewpoint of increasing the hardness, the front surface plate 101 is preferably a film in which a hard coat layer is provided on at least one surface of the base film. As the base film, a film made of the resin can be used. The hard coat layer can be formed on one side of the base film or on both sides. By providing a hard coat layer, a resin film with improved hardness and scratch resistance can be made. The hard coat layer is, for example, a cured layer of ultraviolet curable resin. Examples of ultraviolet curable resins include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. In order to increase the hardness, the hard coat layer may contain additives. The additives are not limited, and examples include inorganic fine particles, organic fine particles, or a mixture of these.

In the case where the front surface plate 101 is a glass plate, the glass plate is preferably a tempered glass for display. The thickness of the glass plate may be 10 μm or more and 1000 μm or less, for example. By using a glass plate, the front surface plate 101 having excellent mechanical strength and surface hardness can be constructed.

In the case where the laminated body 100 is used in a display device, the front surface plate 101 may not only have a function of protecting the front surface (screen) of the display device (function as a window film), but also have a function as a touch sensor, Blu-ray cutoff function, viewing angle adjustment function, etc.

[The first adhesive layer] The first adhesive layer 102 is a layer that is interposed between the front surface plate 101 and the polarizer layer 103 and is bonded together. For example, it can be a layer containing an adhesive or an adhesive, or a layer formed by performing some treatment on the layer.的层。 The layer. The first adhesive layer may be an adhesive layer arranged at a position closest to the front surface plate among the adhesive layers constituting the laminate. Adhesives are also called pressure-sensitive adhesives. The term "adhesive" in this specification refers to an adhesive other than an adhesive (pressure-sensitive adhesive), and is clearly distinguished from an adhesive. The first adhesive layer 102 may include one layer, or may include two or more layers, preferably one layer.

The first adhesive layer 20 may be directly formed of an adhesive composition, or may be formed using an adhesive sheet having an adhesive layer formed using an adhesive composition. The adhesive composition is preferably the adhesive composition A described above. As the adhesive composition other than the adhesive composition A (hereinafter also referred to as the adhesive composition B), for example, rubber-based, urethane-based, ester-based, silicone-based, or polyvinyl ether-based Adhesive composition with resin as the main component. Among them, the adhesive composition B is preferably an adhesive composition excellent in transparency, weather resistance, heat resistance, and the like. The adhesive composition B may be an active energy ray hardening type.

When the adhesive composition B is an active energy ray curable adhesive composition, the active energy ray curable adhesive composition contains an active energy ray polymerizable compound in addition to the raw material polymer. Furthermore, a photopolymerization initiator, photosensitizer, etc. may be contained as needed. In addition, the adhesive composition B may contain additives. Examples of the active energy ray polymerizable compound or photopolymerization initiator are the same as those shown in the description of the (meth)acrylic polymer A.

In the case where the first adhesive layer 102 is formed from the adhesive composition B, the method of forming the first adhesive layer 102 may be the same as the method of forming the first adhesive layer 102 from the adhesive composition A.

The thickness of the first 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 also be 20 μm or more.

[Polarizer layer] As the polarizer layer 103, a stretched film or stretched layer to which a dichroic dye is adsorbed, a layer obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound, and the like can be cited. As the dichroic dye, specifically, iodine or a dichroic organic dye can be used. Dichroic organic dyes include dichroic direct dyes containing C.I. DIRECT RED 39 and other bisazo compounds, and dichroic direct dyes containing compounds such as trisazo and tetrasazo.

Examples of the polarizer layer formed by coating and curing a composition containing a dichroic dye and a polymerizable compound include coating a composition containing a liquid crystal dichroic pigment, or containing a dichroic pigment and A polarizer layer containing a cured product of a polymerizable liquid crystal compound, such as a layer obtained by curing a polymerizable liquid crystal composition. Compared with a stretched film or stretched layer on which a dichroic dye is adsorbed, there is no restriction on the bending direction of the polarizer layer formed by coating and curing a composition containing a dichroic dye and a polymerizable compound. Better.

[Polarizer layer which is stretched film or stretched layer] The polarizer layer of the stretched film that adsorbs the dichroic dye can usually be manufactured through the following steps: the step of uniaxially stretching the polyvinyl alcohol-based resin film; The step of dyeing the film to adsorb the dichroic pigment; the step of treating the polyvinyl alcohol resin film with the dichroic pigment adsorbed with the boric acid aqueous solution; and the step of washing with water after the treatment with the boric acid aqueous 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, and may be 20 μm or less, further may be 15 μm or less, and further may be 10 μm or less.

Polyvinyl alcohol-based resin is obtained by saponifying 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 other monomers that can be copolymerized therewith can also be used. Examples of other monomers that can be copolymerized 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. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may 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 that is the stretched layer to which the dichroic dye is adsorbed can generally be manufactured through the following steps: a step of applying a coating liquid containing the polyvinyl alcohol-based resin on a base film; and laminating the resulting laminate The step of uniaxial stretching of the film; the step of dyeing the polyvinyl alcohol-based resin layer of the uniaxially stretched laminate film with a dichroic dye to adsorb the dichroic dye to prepare a polarizer; using boric acid The step of treating the film with the dichroic dye adsorbed by the aqueous solution; and the step of washing with water after the treatment with the aqueous boric acid solution. If necessary, the base film can be peeled and removed 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 polarizer layer, which is a stretched film or stretched layer, may be assembled in a laminate in a form in which a thermoplastic resin film is bonded on one or both sides. This thermoplastic resin film can function as a protective film for the polarizer layer 103 or a retardation film. The thermoplastic resin film may include, for example, polyolefin resins such as chain polyolefin resins (polypropylene resins, etc.), cyclic polyolefin resins (norbornene resins, etc.); cellulose resins such as triacetyl cellulose. Resins; polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate resins; (meth)acrylic resins; or these The mixture of the film.

From the viewpoint of thinning, the thickness of the thermoplastic resin film is generally 300 μm or less, preferably 200 μm or less, more preferably 100 μm or less, still more preferably 80 μm or less, and still more preferably 60 μm or less. In addition, 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 bonded to the polarizer layer 103 using an adhesive layer, for example.

[Polarizer layer formed by coating and curing a composition containing a dichroic dye and a polymerizable compound] Examples of the polarizer layer formed by applying and curing a composition containing a dichroic dye and a polymerizable compound include a composition containing a polymerizable dichroic dye having liquid crystallinity, or a composition containing a dichroic dye A polarizer layer containing a cured product of a polymerizable liquid crystal compound, such as a layer obtained by applying and curing a composition of a polymerizable liquid crystal to a base film.

If necessary, the base film can be peeled and removed 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. The polarizer layer may include an alignment film. The alignment film can also be peeled off.

The polarizer layer formed by applying and curing a composition containing a dichroic dye and a polymerizable compound can be assembled in an optical laminate in a form in which a thermoplastic resin film is bonded on one or both sides. As the thermoplastic resin film, the same ones as those that can be used in the polarizer layer which is a stretched film or a stretched layer can be used. The thermoplastic resin film can be bonded to the polarizer layer using an adhesive layer, for example.

The polarizer layer formed by coating and hardening a composition containing a dichroic dye and a polymerizable compound can also form an overcoat (OC) layer as a protective layer on one or both sides. Examples include photocurable resins and water-soluble polymers. Examples of the photocurable resin include (meth)acrylic resins, urethane resins, (meth)acrylate urethane resins, epoxy resins, and silicone resins. Examples of water-soluble polymers include: poly(meth)acrylamide-based polymers; polyvinyl alcohol and ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, (meth)acrylic acid or its anhydride- Vinyl alcohol polymers such as vinyl alcohol copolymers; carboxyvinyl polymers; polyvinylpyrrolidone; starches; sodium alginate; polyethylene oxide polymers, etc. The thickness of the OC layer is preferably 20 μm or less, more preferably 15 μm or less, further preferably 10 μm or less, may be 5 μm or less, and may be 0.05 μm or more, or may be 0.5 μm or more.

The thickness of the polarizer layer obtained by coating and curing a composition containing a dichroic dye and a polymerizable compound is usually 10 μm or less, preferably 0.5 μm or more and 8 μm or less, more preferably 1 μm or more and Below 5 μm.

[Second Adhesive Layer] The second adhesive layer 104 is an adhesive layer arranged between the polarizer layer 103 and the back plate 105. The second adhesive layer may be an adhesive layer arranged at a position closest to the back plate among the adhesive layers constituting the laminate. The second adhesive layer 104 may be one layer, or may include two or more layers, preferably one layer.

Regarding the composition and compounding components of the adhesive composition constituting the second adhesive layer 104, the type of the adhesive composition (whether it is an active energy ray hardening type or a thermosetting type, etc.), the additives that can be blended in the adhesive composition, The manufacturing method of the second adhesive layer and the thickness of the second adhesive layer are the same as those shown in the description of the first adhesive layer 102. The second adhesive layer 104 may be the same as or different from the first adhesive layer 102 in terms of the composition, blending components, thickness, etc. of the adhesive composition.

[Back Panel] As the back plate 105, a plate-shaped body capable of transmitting light, a structural member 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 2000 μm or less, preferably 10 μm or more and 1000 μm or less, and more preferably 15 μm or more and 500 μm or less.

The plate-shaped body used for the back panel 105 may be composed of only one layer, may include two or more layers, and the plate-shaped body exemplified in the front panel 101 may be used.

As a structural member used in the normal display device used for the back panel 105, a touch sensor panel, an organic electroluminescent display element, etc. are mentioned, for example. Examples of the stacking order of the constituent components in the display device include: window film/circular polarizer/touch sensor panel/organic EL display element, window film/touch sensor panel/circular polarizer/organic EL Display components, etc.

(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 examples include resistive film method, electrostatic capacitance coupling method, photo sensor method, ultrasonic method, Touch sensor panels of electromagnetic induction coupling method and surface acoustic wave method. In terms of low cost, touch sensor panels of resistive film method and electrostatic capacitance coupling method can be preferably used.

An example of a touch sensor panel of a resistive film method includes a pair of substrates arranged facing each other, an insulating spacer sandwiched between the pair of substrates, and a resistive film provided on the inner front surface of each substrate Transparent conductive film, and touch position detection circuit. In an image display device provided with a resistive film type touch sensor panel, if the surface of the front panel is touched, the opposing resistive films are short-circuited, and current flows through the resistive film. The touch position detection circuit detects the voltage change at this time, thereby detecting the touched position.

An example of the touch sensor panel of the capacitive coupling method includes a substrate, a transparent electrode for position detection provided on the entire surface of the substrate, and a touch position detection circuit. In the image display device provided with the touch sensor panel of the electrostatic capacitance coupling method, if the surface of the front surface plate is touched, the transparent electrode is grounded via the electrostatic capacitance of the human body at the touched point. The touch position detection circuit detects the grounding of the transparent electrode, thereby detecting the touched position.

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

[Phase Difference Layer] The laminated body 100 may further include one or more retardation layers. The retardation layer is usually arranged between the polarizer layer 103 and the back plate 105. The retardation layer may be laminated on the first adhesive layer 102 and the second adhesive layer 104, or may be laminated on other layers via a layer other than these layers containing an adhesive or adhesive (hereinafter also referred to as an adhesive layer) (Including other retardation layers).

[Laminated layer] The bonding layer is a layer disposed between the first adhesive layer 102 and the second adhesive layer 104, and is a layer containing an adhesive or an adhesive. The adhesive constituting the bonding layer may be the same as exemplified for the adhesive composition constituting the first adhesive layer 102 or the second adhesive layer, or other adhesives, such as (meth)acrylic adhesives. Adhesives, styrene-based adhesives, silicone-based adhesives, rubber-based adhesives, urethane-based adhesives, polyester-based adhesives, epoxy-based copolymer adhesives, etc.

As the adhesive that constitutes the bonding layer, for example, it can be formed by combining one or two or more of water-based adhesives, active energy ray curable adhesives, adhesives, and the like. Examples of the water-based adhesive include a polyvinyl alcohol-based resin aqueous solution, an aqueous two-component urethane-based emulsion adhesive, and the like. The active energy ray-curable adhesive is an adhesive that is cured by irradiating active energy rays such as ultraviolet rays. Examples include those containing polymerizable compounds and photopolymerizable initiators, those containing photoreactive resins, and those containing adhesives. Resins and photoreactive crosslinkers, etc. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, or those derived from these monomers. Body oligomers, etc. Examples of the photopolymerization initiator include those containing active species such as neutral radicals, anionic radicals, and cationic radicals by irradiating 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 still more preferably 2.5 μm or more and 5 μm or less.

The laminate 100 shown in FIG. 2 includes a front surface plate 101, a first adhesive layer 102, a polarizer layer 103, a second adhesive layer 104, and a back plate 105, and further includes a bonding layer 108 and a first retardation layer 106 .

The laminate 100 shown in FIG. 3 includes a front surface plate 101, a first adhesive layer 102, a polarizer layer 103, a second adhesive layer 104, and a back plate 105, and further includes a bonding layer 108 and a first retardation layer 106 , The bonding layer 109 and the second retardation layer 107.

Examples of the retardation layer include a positive A plate such as a λ/4 plate or a λ/2 plate, and a positive C plate. The retardation layer may be, for example, a retardation film that can be formed from the thermoplastic resin film, or a layer formed by curing a polymerizable liquid crystal compound, that is, a layer containing a cured product of a polymerizable liquid crystal compound, and the latter is preferred. The thickness of the retardation film may be the same as the thickness of the thermoplastic resin film. The thickness of the retardation layer formed 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 it. An alignment layer may also 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. The retardation layer formed by curing the polymerizable liquid crystal compound may be assembled in the laminate 100 in a form having an alignment layer and/or a base film. The back plate 105 may also be a base film for coating the composition.

As described above, the bonding layer 108 may use an adhesive or an adhesive. The adhesive may be the adhesive composition A or the adhesive composition B. As the adhesive, a water-based adhesive or an active energy ray curable adhesive can be used. As an aqueous adhesive agent, the adhesive agent containing a polyvinyl alcohol-type resin aqueous solution, an aqueous two-component type urethane type emulsion adhesive agent, etc. are mentioned.

The so-called active energy ray curable adhesive refers to an adhesive that is cured by irradiating active energy rays such as ultraviolet rays. Examples include: those containing polymerizable compounds and photopolymerization initiators, those containing photoreactive resins, and those containing adhesive Agent resin and photoreactive crosslinking agent. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable (meth)acrylic monomers, and photocurable urethane monomers, or those derived from Oligomers of photopolymerizable monomers, etc. Examples of the photopolymerization initiator include a photopolymerization initiator containing a substance that generates active species such as neutral radicals, anionic radicals, and cationic radicals by irradiation 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-based monomer and a photocationic polymerization initiator can be preferably used.

[Method of manufacturing laminate] The laminate 100 can be manufactured by a method including the steps in which the layers constituting the laminate 100 are bonded to each other through an adhesive layer or further through an adhesive layer. When bonding layers to each other via an adhesive layer or an adhesive layer, in order to improve adhesion, it is preferable to perform surface activation treatment such as corona treatment on one or both sides of the bonding surface. The polarizer layer 103 can be directly formed on a thermoplastic resin film or a base film, and the thermoplastic resin film or base film may be assembled in the laminate 100 or may be peeled from the polarizer layer 103 and not used as a component of the laminate.

＜Display device＞ The display device of the present invention includes the laminate 100 of the present invention. The display device is not particularly limited, and examples thereof include image display devices such as organic EL display devices, inorganic EL display devices, liquid crystal display devices, and electroluminescence display devices. The display device may also have a touch panel function. The optical laminate is suitable for a display device having flexibility that can be bent or folded.

In the display device, the optical laminate has the front surface plate facing outward (the side opposite to the display element side, that is, the visible side), and is arranged on the visible side of the display element included in the display device.

The display device of the present invention can be used as mobile devices such as smart phones, input panels, televisions, digital photo frames, electronic billboards, measuring devices or meters, office equipment, medical equipment, computer equipment, etc.

＜Adhesive composition＞ The adhesive composition of the present invention contains a (meth)acrylic polymer that is derived from (meth)acrylate or (meth)acrylate and contains the formula ( I) The structural unit of the monomer of the structure shown; preferably the adhesive composition A.

＜Adhesive sheet＞ The adhesive sheet of the present invention includes an adhesive layer formed of an adhesive composition containing a (meth)acrylic polymer, the (meth)acrylic polymer containing a layer derived from (meth)acrylate or (meth)acrylate ) Structural units of amide acrylate and containing monomers of the structure represented by the formula (I); preferably including an adhesive layer formed of the adhesive composition A. The adhesive layer can be formed by coating the adhesive composition on the substrate. In the case of using an active energy ray-curable adhesive composition as the adhesive composition, by irradiating the formed adhesive layer with active energy rays, a cured product having a desired degree of curing can be obtained.

The substrate may be a release film that has been subjected to mold release treatment. The adhesive sheet can be produced by pre-forming a layer containing an adhesive on the release film into a sheet shape, and then attaching another release film on the adhesive layer.

The adhesive layer of the adhesive sheet of the present invention has excellent adhesiveness. If the shear stress relaxation rate at a temperature of 25°C of a reference adhesive layer with a thickness of 150 μm formed from the adhesive composition used in the formation of the adhesive layer is R ₀ , it is preferable to satisfy the following relational expression (4): 0.02≦R ₀ ≦0.25 (4), it is more preferable to satisfy the following relational expression (4a): 0.10≦R ₀ ≦0.20 (4a).

By using an adhesive composition that satisfies the above-mentioned relational expression, an adhesive sheet with excellent room temperature adhesion durability can be produced. [Example]

Hereinafter, the present invention will be explained in more detail with examples, but the present invention is not limited by these examples.

<Preparation of (meth)acrylic polymer A1 to (meth)acrylic polymer A4> The monomers shown in Table 1 were mixed and copolymerized to obtain (meth)acrylic polymer A1 to (meth)acrylic polymer A4. The monomer amounts in the table are parts by mass. In addition, the measured weight average molecular weight (Mw) is shown in Table 1.

<Preparation of adhesive composition B1-adhesive composition B4> 100 parts by mass of the (meth)acrylic polymer obtained in the above steps (solid content conversion value; the same below), and trimethylolpropane as a thermal crosslinking agent modified dimethyl diisocyanate (Soken Chemical Co., Ltd. Manufacture, product name "TD-75") and 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM403") as a silane coupling agent in the amount shown in Table 1 (mass Parts) mix and stir well. The mixture was diluted with methyl ethyl ketone to obtain coating solutions of the adhesive composition B1 to the adhesive composition B4.

[Table 1] Adhesive composition (Meth) acrylic polymer (Meth) acrylic polymer preparation Thermal crosslinking agent Silane coupling agent Adhesive sheet shear stress relaxation rate R ₀ BA 2EHA 4HBA Weight average molecular weight (Mw) B1 A1 54 45 1.0 800 000 0.25 0.2 0.15 B2 A2 54 45 1.0 1.2 million 0.15 0.2 0.19 B3 A3 54 45 1.0 800 000 0.4 0.2 0.18 B4 A4 52 45 3.0 800 000 0.25 0.2 0.14

The abbreviations in Table 1 indicate the following. BA: n-butyl acrylate 2EHA: 2-ethylhexyl acrylate 4HBA: 4-hydroxybutyl acrylate

＜Making of Adhesive Sheet＞

Apply the coating solution of adhesive composition B1 to adhesive composition B4 to the peeling treatment surface of release film A (manufactured by Lintec, product name "SP-PET752150") using a knife coater . Then, the coating layer was heat-treated at 90°C for 1 minute to form the coating layer. Then, the coating layer on the peeling film A obtained above and the peeling film B (manufactured by Lintec Co., Ltd., product name "SP -PET382120”), and cured for 7 days under the conditions of 23°C and 50%RH to produce an adhesive sheet having an adhesive layer with a thickness of 25 μm, that is, including peeling film A/adhesive layer (thickness: 25 μm) / Adhesive sheet composed of release film B. In addition, the thickness of an adhesive layer is the value measured by the method mentioned later. Using the obtained adhesive sheet, a reference adhesive layer was produced by the method described later, and the shear stress relaxation rate was measured. The results are shown in Table 1.

<Preparation of (meth)acrylic polymer A5-(meth)acrylic polymer A8> (Manufacturing example A5) In order to reflux the nitrogen gas and easily adjust the temperature, a 1 L reactor equipped with a cooling device was charged with 70% by mass of 2-ethylhexyl acrylate (2-EHA) monomer and hydroxypropyl methacrylate (HPMA) monomer. After a monomer mixture containing 9.9% by mass and 20% by mass of lauryl acrylate (LA) monomer, nitrogen was refluxed for 1 hour in order to remove oxygen, and the temperature was maintained at 80°C. After the monomer mixture was uniformly mixed, the photopolymerization initiator benzil dimethyl ketal (I-651) 0.05% by mass and 1-hydroxycyclohexyl phenyl ketone (I-184) 0.05% by mass were added. Then, a UV lamp (10 mW) was irradiated while stirring to produce (meth)acrylate polymer A5 having a weight average molecular weight (Mw) of 400,000.

(Manufacturing example A6) In order to reflux the nitrogen gas and easily adjust the temperature, a 1-L reactor equipped with a cooling device was charged with 75% by mass of 2-ethylhexyl acrylate (2-EHA) monomer and tetrahydrofurfuryl methacrylate (THFMA) After a monomer mixture of 4.9% by mass of the monomer and 20% by mass of the lauryl acrylate (LA) monomer, nitrogen was refluxed for 1 hour in order to remove oxygen, and the temperature was maintained at 80°C. After the monomer mixture was uniformly mixed, the photopolymerization initiator benzil dimethyl ketal (I-651) 0.05% by mass and 1-hydroxycyclohexyl phenyl ketone (I-184) 0.05% by mass were added. Then, a UV lamp (10 mW) was irradiated while stirring to produce (meth)acrylate polymer A6 having a weight average molecular weight (Mw) of 450,000.

(Manufacturing example A7) In order to reflux the nitrogen gas and easily adjust the temperature, a 1 L reactor equipped with a cooling device was charged with 70% by mass of 2-ethylhexyl acrylate (2-EHA) monomer and cyclohexyl methacrylate (CHMA) monomer. After containing 2.5% by mass of the monomer mixture and 27.4% by mass of lauryl acrylate (LA) monomer, nitrogen was refluxed for 1 hour in order to remove oxygen, and the temperature was maintained at 80°C. After the monomer mixture was uniformly mixed, the photopolymerization initiator benzil dimethyl ketal (I-651) 0.05% by mass and 1-hydroxycyclohexyl phenyl ketone (I-184) 0.05% by mass were added. Then, a UV lamp (10 mW) was irradiated while stirring to produce (meth)acrylate polymer A7 having a weight average molecular weight (Mw) of 500,000.

(Manufacturing example A8) In order to reflux the nitrogen gas and easily adjust the temperature, a 1-L reactor equipped with a cooling device was charged with 87% by mass of 2-ethylhexyl acrylate (2-EHA) monomer and hydroxypropyl methacrylate (HPMA) monomer. After a monomer mixture containing 3.0% by mass of tetrahydrofurfuryl methacrylate (THFMA) monomer, 3.0% by mass of lauryl acrylate (LA) monomer, and 6.9% by mass of lauryl acrylate (LA) monomer, nitrogen was refluxed for 1 hour in order to remove oxygen. It is 80°C. After the monomer mixture was uniformly mixed, the photopolymerization initiator benzil dimethyl ketal (I-651) 0.05% by mass and 1-hydroxycyclohexyl phenyl ketone (I-184) 0.05% by mass were added. Then, a UV lamp (10 mW) was irradiated with stirring to produce (meth)acrylate polymer A8 having a weight average molecular weight (Mw) of 350,000.

The composition and weight average molecular weight (Mw) of Production Example A5 to Production Example A8 are summarized in Table 2.

[Table 2] (Meth) acrylic polymer Preparation of (meth)acrylic polymer (mass%) 2-EHA HPMA THFMA CHMA LA I-651 I-184 Weight average molecular weight (Mw) A5 70 9.9 - - 20 0.05 0.05 400000 A6 75 - 4.9 - 20 0.05 0.05 450,000 A7 70 - - 2.5 27.4 0.05 0.05 500000 A8 87 3.0 3.0 - 6.9 0.05 0.05 350,000

The abbreviations in Table 2 indicate the following. 2-EHA: 2-ethylhexyl acrylate (Tokyo Chemical Industry Co., Ltd., Japan), HPMA: Hydroxypropyl methacrylate (Tokyo Chemical Industry Co., Ltd., Japan), THFMA: Tetrahydrofurfuryl methacrylate (Tokyo Chemical Industry Co., Ltd., Japan), CHMA: Cyclohexyl methacrylate (Tokyo Chemical Industry Co., Ltd., Japan), LA: Lauryl Acrylate (Tokyo Chemical Industry Co., Ltd., Japan), I-651: benzil dimethyl ketal (photopolymerization initiator, BASF, Germany), I-184: 1-hydroxycyclohexyl phenyl ketone (photopolymerization initiator, BASF, Germany).

<Preparation of adhesive composition B5-adhesive composition B8> They were mixed according to the components and ratios shown in Table 3 to produce adhesive composition B5 to adhesive composition B8. The addition amount in the table is mass %.

[table 3] Adhesive composition (Meth) acrylic polymer additive Photopolymerization initiator Adhesive sheet shear stress relaxation rate R ₀ species Allocation amount BA BPO B5 A5 97.5 2 0.5 0.22 B6 A6 89.5 10 0.5 0.05 B7 A7 99 0.5 0.5 0.08 B8 A8 99 0.5 0.5 0.20

The abbreviations in Table 3 indicate the following. BA: Butyl Acrylate (Tokyo Chemical Industry Co., Ltd., Japan), BPO: Benzophenone (Tokyo Chemical Industry Co., Ltd., Japan).

＜Making of Adhesive Sheet＞ Apply adhesive composition B5 to adhesive composition B8 to a light release film A (polyethylene terephthalate film, thickness 38 μm) coated with silicon release agent in a thickness of 25 μm . The heavy release film B (polyethylene terephthalate film, thickness 38 μm) was bonded thereon, and UV irradiation was performed to produce an adhesive sheet including release film A/adhesive layer/release film B. Using the obtained adhesive sheet, a reference adhesive layer was produced by the method described later, and the shear stress relaxation rate was measured. The results are shown in Table 3.

[Determination of weight average molecular weight (Mw)] The weight average molecular weight (Mw) of the (meth)acrylic polymer is the number average molecular weight (Mn) in terms of polystyrene. Tetrahydrofuran is used in the mobile phase, and the following particle size sieve chromatography (size exclusion chromatography, SEC). The measured (meth)acrylic polymer was dissolved in tetrahydrofuran at a concentration of about 0.05% by mass, and 10 μL was injected into a size exclusion chromatograph (SEC). The mobile phase flows at a flow rate of 1.0 mL/min. As the column, PLgel MIXED-B (manufactured by Polymer Laboratories) was used. The detector used an ultraviolet-visible light detector (UV-VIS detector) (trade name: Agilent GPC).

[Layer thickness] The measurement was performed using a contact-type film thickness measuring device ("MS-5C" manufactured by Nikon Co., Ltd.). Among them, the polarizer layer and the alignment film were measured using a laser microscope (“OLS3000” manufactured by Olympus Co., Ltd.).

[Shear stress relaxation rate] The shear stress relaxation rate was measured using a viscoelasticity measuring device (MCR-301, Anton Paar). The adhesive sheet was cut into a width of 20 mm × a length of 20 mm, the release film was peeled off, and multiple sheets were laminated with a thickness of 150 μm and joined to a glass plate. In the state of being attached to the measuring wafer, at a temperature of 25°C, the deformation is stopped with a normal force of 1 N and a deformation amount of 10%, and the shear elastic modulus after 300 seconds is measured. . Based on these measured values, the shear stress relaxation rate R _{0 was} calculated from the following equation. R ₀ = Shear elastic coefficient after 300 seconds / Shear elastic coefficient after _0.1 seconds

[Layered body of Example 1 to Example 6, Comparative Example 1] As Example 1-Example 6 and Comparative Example 1, the laminated body 100 shown in FIG. 2 was produced.

<The first adhesive layer 102 and the second adhesive layer 104> As an adhesive sheet including the first adhesive layer 102 and the second adhesive layer 104, an adhesive sheet formed of each adhesive composition shown in Table 1 and Table 3 was prepared. Hereinafter, the adhesive sheet for the first adhesive layer 102 is referred to as the first adhesive sheet, and the adhesive sheet for the second adhesive layer 104 is referred to as the second adhesive sheet.

＜Front surface plate 101＞ As the window film for the front surface plate 101, a polyimide film (HC-PI) having a hard coat layer on one side, the overall thickness: 60 μm, the thickness of the hard coat layer: 10 μm, and the polyimide film are prepared Thickness: 50 μm).

<Polarizer layer 103> [Layered body with polarizer layer] (Polymerizable liquid crystal compound) The polymerizable liquid crystal compound uses a polymerizable liquid crystal compound represented by formula (1-6) [hereinafter also referred to as compound (1-6) ] And the polymerizable liquid crystal compound represented by formula (1-7) [hereinafter also referred to as compound (1-7)].

Compounds (1-6) and compounds (1-7) were obtained from "Recl. Trav. Chim. Pays-Bas" by Lub et al. (Lub et al.), 115, 321-328 ( The method described in 1996) was synthesized.

(Dichroic dye) The dichroic dye is described in the examples of Japanese Patent Laid-Open No. 2013-101328, represented by the following formulas (2-1a), (2-1b), and (2-3a) The azo pigment.

(Composition for forming polarizer layer) The composition for forming a polarizer layer was prepared by combining 75 parts by mass of compound (1-6), 25 parts by mass of compound (1-7), and the formula (2-1a) as a dichroic dye. 2.5 parts by mass of each of the azo dyes represented by formula (2-1b) and formula (2-3a), 2-dimethylamino-2-benzyl-1-(4-morpholine) as a polymerization initiator (Phenyl) butan-1-one (Irgacure 369, manufactured by BASF Japan) 6 parts by mass, and a polyacrylate compound (BYK-361N, BYK Chemie) as a leveling agent (Manufactured by BYK-Chemie) 1.2 parts by mass were mixed with 400 parts by mass of toluene as a solvent, and the resulting mixture was stirred at 80°C for 1 hour.

根據GPC測定，所得的聚合物1的分子量顯示出數量平均分子量為28200、Mw/Mn為1.82，單體含量為0.5%。(Composition for forming alignment film) The polymer 1 is a polymer having a photoreactive group including the following structural unit.

According to GPC measurement, the molecular weight of the obtained polymer 1 showed a number average molecular weight of 28,200, a Mw/Mn of 1.82, and a monomer content of 0.5%.

A solution obtained by dissolving the polymer 1 in cyclopentanone at a concentration of 5% by mass was used as the composition for forming an alignment film.

(Composition for protective layer) The composition for the protective layer is composed of 3 parts by mass of polyvinyl alcohol resin powder (manufactured by Kuraray Co., Ltd., with an average degree of polymerization of 18000, trade name: KL-318) relative to 100 parts by mass of water, and polyamide Epoxy resin (crosslinking agent, manufactured by Sumika Chemtex Co., Ltd., trade name: SR650 (30)) 1.5 parts by mass was mixed and prepared.

(Production of a laminate with a polarizer layer) The composition for forming an alignment film was coated by a bar coating method on a corona treatment (output 0.3 kW, processing speed 3 m/min) triacetyl cellulose ( On triacetyl cellulose (TAC) film (thickness 25 μm), heat and dry in a drying oven at 80°C for 1 minute. The obtained dry coating film was subjected to a polarization UV irradiation treatment to form a first alignment film (AL1). Polarized UV treatment is to make light irradiated from a UV irradiation device ("SPOT CURE SP-7" manufactured by Usio Electric Co., Ltd.) pass through a wire grid ("UIS-27132" manufactured by Ushio Electric Co., Ltd.) ##”) and the cumulative light intensity measured at a wavelength of 365 nm is 100 mJ/cm ² . The thickness of the first alignment film (AL1) is 100 nm.

On the formed first alignment film (AL1), the composition for forming a polarizer layer was coated by a bar coating method, heated and dried in a drying oven at 120° C. for 1 minute, and then cooled to room temperature. Using the UV irradiation device, the dried coating film was irradiated with ultraviolet rays at a cumulative light amount of 1200 mJ/cm ² (365 nm reference), thereby forming a polarizer layer (pol). The thickness of the obtained polarizer layer was 1.8 μm.

On the formed polarizer layer, the protective layer composition was applied by a bar coating method, applied 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 including TAC film/first alignment film (AL1)/polarizer layer/protective layer is obtained.

＜First retardation layer 106＞ [Laminated body with retardation layer] (Composition for forming retardation layer) Each component shown below was mixed, and the obtained mixture was stirred at 80 degreeC for 1 hour, and the composition for retardation layer formation was obtained.

Compound b-1 represented by the following formula: 80 parts by weight

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

Polymerization initiator (Irgacure 369, 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl) butan-1-one, BASF Japan) Made by the company): 6 parts by mass Leveling agent (BYK-361N, polyacrylate compound, manufactured by BYK-Chemie): 0.1 parts by mass Solvent (cyclopentanone): 400 parts by mass

(Production of laminated body with retardation layer) A polyethylene terephthalate (PET) film with a thickness of 100 μm was prepared as a base material, and the composition for forming an alignment film was applied to the substrate by bar coating. The film was heated and dried in a drying oven at 80°C for 1 minute. The obtained dry film is subjected to a polarization UV irradiation treatment to form a second alignment film (AL2). The polarized UV treatment was performed using the UV irradiation device described above under the condition that the cumulative light amount measured at a wavelength of 365 nm was 100 mJ/cm ² . In addition, it was performed so that the polarization direction of the polarized light UV was 45° with respect to the absorption axis of the polarizer layer.

On the obtained second alignment film (AL2), the retardation layer forming composition was coated by a bar coating method, heated and dried in a drying oven at 120° C. for 1 minute, and then cooled to room temperature. The obtained dry film was irradiated with ultraviolet rays having a cumulative light intensity of 1000 mJ/cm ² (based on 365 nm) using the UV irradiation device to form a retardation layer. The thickness of the obtained retardation layer was measured by a laser microscope (OLS3000 manufactured by Olympus Co., Ltd.) and it was 2.0 μm. The retardation layer is a λ/4 plate (Quarter-Wave Plate (QWP)) that displays a λ/4 retardation value in the in-plane direction. In this way, a laminate including the base material (PET)/second alignment film (AL2)/phase difference layer (QWP) is obtained.

＜Lamination layer 108＞ The following components were reacted at 55°C while stirring in a nitrogen atmosphere, thereby obtaining an acrylic resin. Butyl acrylate: 70 parts Methyl acrylate: 20 parts Acrylic: 2.0 parts Free radical polymerization initiator (2,2'-azobisisobutyronitrile): 0.2 parts

The following components are mixed to obtain an adhesive composition. The acrylic resin: 100 parts Crosslinking agent ("Coronate L" manufactured by Tosoh Corporation): 1.0 part Silane coupling agent ("X-12-981" manufactured by Shin-Etsu Silicon Co., Ltd.): 0.5 parts Ethyl acetate was added so that the total solid content concentration was 10% to obtain an adhesive composition.

Using an applicator, apply the adhesive composition to the release-treated heavy release film B (polyethylene terephthalate film, thickness 38 μm) so that the thickness after drying is 5 μm. Treatment surface. The coating layer was dried at 100°C for 1 minute to obtain a film including an adhesive layer. Thereafter, on the exposed surface of the adhesive layer, a release-treated lightly peelable film A (polyethylene terephthalate film, thickness 38 μm) was attached. Thereafter, it was cured for 7 days under the conditions of a temperature of 23° C. and a relative humidity of 50% RH to obtain an adhesive sheet.

＜Back panel 105＞ As the back plate 105, a polyethylene terephthalate substrate (thickness 38 μm) or a glass substrate is prepared.

＜Manufacture of laminated body 100＞ The laminates of Examples 1 to 6 and Comparative Example 1 were produced in the following procedures. In addition, in the formation of the first adhesive layer and the second adhesive layer, the adhesive sheet formed of the adhesive composition shown in Table 1 and Table 3 was used in the combination shown in Table 4.

First, after peeling off the release film A of the adhesive sheet for the bonding layer, corona treatment is performed on the exposed adhesive layer. The surface of the protective layer side of the laminate including the polarizer layer is corona treated. The pressure-sensitive adhesive sheet for the bonding layer and the laminate including the polarizer layer were bonded so that the surface subjected to the corona treatment became the bonding surface, to obtain a laminate A1.

After peeling off the other release film B of the adhesive sheet for the bonding layer from the laminate A1, corona treatment was performed on the exposed bonding layer. The surface of the layered body including the retardation layer on the side of the retardation layer was corona treated, and the layered body A1 and the layered body including the retardation layer were laminated so that the corona-treated surface became a bonding surface The body is bonded together to obtain a laminate A2.

The PET film was peeled from the laminate A2, and the surface on the side of the retardation layer was corona treated. The release film A of the second adhesive sheet was peeled off, and the surface of the adhesive layer was corona treated. The layered body A2 and the second adhesive layer were bonded together so that the surface subjected to the corona treatment became a bonding surface, and a layered body A3 was obtained.

The release film A was peeled off from the first adhesive sheet, and corona treatment was performed on the surface of the adhesive layer. The surface on the PI side of the front surface plate was also corona treated, and the first adhesive layer was bonded to the front surface plate so that the corona-treated surface became a bonding surface to obtain a laminate A4.

The surface of the layered body A3 on the TAC film side was corona treated. The release film B of the laminate A4 was peeled off, and the surface of the first adhesive layer was corona treated. The laminated body A3 and the laminated body A4 were bonded together so that the corona-treated surface became a bonding surface, and the laminated body A5 was obtained.

The release film B of the laminate A5 was peeled off, and it was bonded to a polyethylene terephthalate substrate to prepare a laminate for evaluation of flexibility at room temperature.

In addition, the release film B of the laminate A5 was peeled off, and the laminate was bonded to a glass substrate to prepare a laminate for the test of adhesion durability at room temperature.

In this way, it includes the window film/first adhesive layer/TAC film layer/first alignment film (AL1)/polarizer layer/protective layer/laminated layer/second alignment film (AL2)/phase difference layer/second 2. Laminated body of adhesive layer/back panel.

Corona treatment is carried out under the conditions of output: 0.3 KW and speed: 3 m/min.

The obtained laminates of Examples 1 to 6 and Comparative Example 1 were evaluated for room temperature flexibility and room temperature adhesion durability. The results are shown in Table 4.

[Table 4] Example Comparative example 1 2 3 4 5 6 1 First adhesive layer Types of adhesive composition B2 B2 B2 B2 B5 B8 B6 Shear stress relaxation rate R ₀ 1 0.19 0.19 0.19 0.19 0.22 0.20 0.05 Second adhesive layer Types of adhesive composition B1 B2 B3 B4 B6 B7 B5 Shear stress relaxation rate R ₀ 2 0.15 0.19 0.18 0.14 0.05 0.08 0.22 Evaluation Flexibility at room temperature A C A B B B E Adhesion durability at room temperature A A A A A A C

[Normal temperature flexibility] For the laminate, a bending evaluation device (manufactured by Science Town, STS-VRT-500) was used to conduct an evaluation test to confirm the bending property at room temperature. 4(a) and 4(b) are diagrams schematically showing the method of this evaluation test. As shown in Fig. 4, the two mounting tables 501 and 502 that can be moved separately are arranged so that the gap C is 6 mm (bending radius 3 mm), the center in the width direction is located at the center of the gap C, and the polyparaphenylene The ethylene dicarboxylate substrate is located on the upper side, and the laminate is fixedly arranged in this manner (Fig. 4(a)). Then, the two mounting tables 501 and 502 are rotated upward by 90 degrees with the positions P1 and P2 as the center of the rotation axis, and bending force is applied to the region of the laminate corresponding to the gap C of the mounting table (Figure 4(b)) ). After that, the two mounting tables 501 and 502 are returned to their original positions (FIG. 4(a)). After completing the above series of operations, count the number of times the bending force is applied as one. After repeating this at a temperature of 25°C, it was confirmed whether or not bubbles in the adhesive layer were generated in the region corresponding to the gap C between the mounting table 501 and the mounting table 502 of the layered body. The moving speed of the mounting table 501 and the mounting table 502, and the application step width of the bending force were set to the same conditions in the evaluation test of any laminate. A: Even if the number of applications of bending force reached 100,000, no bubbles were generated. B: Air bubbles are generated when the number of application of bending force is 50,000 or more and less than 100,000. C: Air bubbles are generated when the number of times the bending force is applied is 20,000 or more and less than 50,000. D: Air bubbles are generated when the number of application of bending force is 10,000 or more and less than 20,000. E: Air bubbles are generated when the number of application of bending force is less than 10,000.

[Adhesion durability at room temperature] Adhesion durability at room temperature was tested using a laminate in which a glass substrate was bonded as described above instead of a polyethylene terephthalate substrate. Specifically, after cutting the laminate A5 in a width of 100 mm × a length of 100 mm, the release film B is peeled off from the second adhesive layer, and bonded to an alkali-free glass substrate to obtain a room temperature adhesive durability Laminated body for testing. After treating the test piece in an autoclave at a temperature of 50° C. and a pressure of 5 atmospheres for 20 minutes, it was kept under constant temperature and humidity conditions (temperature of 23° C., relative humidity of 50%) for 4 hours. After that, it was left in an oven at 25°C for 250 hours, and the test piece was observed for floatation, peeling, and bubbles. The evaluation criteria are as follows. ○: Almost no appearance changes such as floating, peeling, and foaming are observed. △: The appearance changes such as floating, peeling, and foaming are slightly noticeable. ×: Appearance changes such as floating, peeling, and foaming are clearly seen.

Examples 1 to 6 satisfy the relationship of "R ₀ 1≧R ₀ 2", and therefore can be judged to satisfy the relationship of "R1≧R2". On the other hand, Comparative Example 1 has a relationship of "R ₀ 1<R ₀ 2", so it can be judged as a relationship of "R1<R2".

100: layered body 101: front panel 102: The first adhesive layer 103: Polarizer layer 104: second adhesive layer 105: back panel 106: first phase difference layer 107: second retardation layer 108, 109: Laminated layer 501, 502: Mounting table C: gap P1, P2: position

Fig. 1 is a schematic cross-sectional view showing an example of the laminate of the present invention. Fig. 2 is a schematic cross-sectional view showing an example of the laminate of the present invention. Fig. 3 is a schematic cross-sectional view showing an example of the laminate of the present invention. 4(a) and 4(b) are schematic diagrams explaining the method of the bendability test.

100: layered body

101: front panel

102: The first adhesive layer

103: Polarizer layer

104: second adhesive layer

105: back panel

Claims (8)

A layered body, in turn, includes: a front surface plate; a first adhesive layer formed by using a first adhesive composition; a polarizer layer; a second adhesive layer formed by using a second adhesive composition; And the back panel, If the shear stress relaxation rate at the temperature of the first adhesive layer at 25°C is set to R1 and the shear stress relaxation rate at the temperature of the second adhesive layer at 25°C is set to R2, the following The relational formula (1): R1≧R2 (1). The laminate according to claim 1, wherein the shear stress relaxation rate at a temperature of 25° C. of a first reference adhesive layer with a thickness of 150 μm formed using the first adhesive composition is R ₀ 1 , The second reference adhesive layer with a thickness of 150 μm formed by using the second adhesive composition has a shear stress relaxation rate at a temperature of 25°C as R ₀ 2, then the following relationship (2) and Relational formula (3): 0.02≦R ₀ 1≦0.25 (2) 0.02≦R ₀ 2≦0.25 (3). The laminate according to claim 1 or 2, wherein the first adhesive composition and the second adhesive composition both contain a (meth)acrylic polymer. The laminate according to claim 3, wherein the weight average molecular weight (Mw) of the (meth)acrylic polymer is 200,000 or more and 1.5 million or less. The laminate according to claim 3 or claim 4, wherein in the (meth)acrylic polymer, based on the total mass of the polymer, the constituent unit derived from a monomer having a reactive functional group is less than 5 mass%. The laminate according to any one of claim 1 to claim 5, wherein the back panel is a touch sensor panel. A display device includes the laminate according to any one of claim 1 to claim 6. The display device according to claim 7, which can bend the front surface plate side outward.

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