阅读说明：本技术 层叠体 (Laminated body ) 是由 李昇祐 金正熙 于 2020-02-07 设计创作，主要内容包括：本发明的目的在于提供一种即使在使前面板侧为外侧进行弯曲的情况下,也能够抑制气泡的产生且在高温环境下粘合力优异的层叠体。本发明提供一种层叠体,依次包含前面板、使用第1粘合剂组合物形成的第1粘合剂层、起偏器层、使用第2粘合剂组合物形成的第2粘合剂层以及背面板,如果将上述第1粘合剂层的热分解质量减少率设为R1[％]、将上述第2粘合剂层的热分解质量减少率设为R2[％],则满足下述关系式(1)：R1≤R2(1),所述第1粘合剂层和所述第2粘合剂层的热分解质量减少率为10质量％～20质量％。(The purpose of the present invention is to provide a laminate that can suppress the occurrence of air bubbles and has excellent adhesive strength in a high-temperature environment even when the front panel side is bent to the outside. The present invention provides a laminate comprising a front sheet, a1 st adhesive layer formed using a1 st adhesive composition, a polarizer layer, a2 nd adhesive layer formed using a2 nd adhesive composition, and a back sheet in this order, wherein the following relational expression (1) is satisfied if the thermal decomposition mass reduction rate of the 1 st adhesive layer is R1 [% ], and the thermal decomposition mass reduction rate of the 2 nd adhesive layer is R2 [% ]: r1 ≦ R2(1), and the thermal decomposition mass reduction rate of the 1 st adhesive layer and the 2 nd adhesive layer is 10 to 20 mass%.)

1. A laminate comprising, in this order, a front sheet, a1 st adhesive layer formed using a1 st adhesive composition, a polarizer layer, a2 nd adhesive layer formed using a2 nd adhesive composition, and a back sheet,

when the thermal decomposition mass reduction rate of the 1 st adhesive layer is R1 [% ], and the thermal decomposition mass reduction rate of the 2 nd adhesive layer is R2 [% ], the following relational expression (1) is satisfied:

R1≤R2 (1)，

the thermal decomposition mass reduction rate of the 1 st adhesive layer and the 2 nd adhesive layer is 10 to 20 mass%.

2. The laminate according to claim 1, wherein each of the 1 st adhesive composition and the 2 nd adhesive composition comprises a (meth) acrylic polymer,

in the (meth) acrylic polymer, the constituent unit derived from the monomer having a reactive functional group is less than 5% by mass based on the total mass.

3. The laminate according to claim 1 or 2, wherein each of the 1 st adhesive layer and the 2 nd adhesive layer comprises a (meth) acrylic polymer,

the weight average molecular weight (Mw) of the (meth) acrylic polymer is 20 to 150 ten thousand.

4. The laminate according to any one of claims 1 to 3, wherein the back sheet is a touch sensor panel.

5. A display device comprising the laminate according to any one of claims 1 to 4.

6. The display device according to claim 5, wherein the front panel side can be bent to an outer side.

Technical Field

The present invention relates to a laminate.

Background

Jp 2018 a-28573 (patent document 1) describes a laminate for a flexible image display device having a plurality of adhesive layers.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-28573

Disclosure of Invention

In a display device including a laminate including a front panel and a plurality of adhesive layers, when the front panel is bent with the front panel side being the outer side, air bubbles may be generated in the adhesive layers in the laminate. In addition, the adhesive force of the adhesive layer is weak in a high-temperature environment, and floating or peeling may occur between the adhesive layer and the member to be bonded.

The purpose of the present invention is to provide a laminate that can suppress the occurrence of air bubbles and has excellent adhesive strength in a high-temperature environment even when the front panel side is bent to the outside.

The present invention provides the following laminate.

[1] A laminate comprising a front sheet, a1 st adhesive layer formed using a1 st adhesive composition, a polarizer layer, a2 nd adhesive layer formed using a2 nd adhesive composition, and a back sheet in this order,

when the thermal decomposition mass reduction rate of the 1 st pressure-sensitive adhesive layer is R1 [% ], and the thermal decomposition mass reduction rate of the 2 nd pressure-sensitive adhesive layer is R2 [% ], the following relational expression (1) is satisfied:

R1≤R2 (1)

the thermal decomposition mass reduction rate of the 1 st adhesive layer and the 2 nd adhesive layer is 10 to 20 mass%.

[2] the laminate according to [1], wherein the 1 st adhesive composition and the 2 nd adhesive composition each contain a (meth) acrylic polymer,

in the (meth) acrylic polymer, the constituent unit derived from the monomer having a reactive functional group is less than 5% by mass based on the total mass.

[ 3] the laminate according to [1] or [2], wherein the 1 st adhesive layer and the 2 nd adhesive layer each contain a (meth) acrylic polymer,

the weight average molecular weight (Mw) of the (meth) acrylic polymer is 20 to 150 ten thousand.

The laminate according to any one of [1] to [ 3], wherein the back panel is a touch sensor panel.

A display device comprising the laminate according to any one of [1] to [ 4 ].

[ 6 ] according to the display device described above in [ 5 ], the front panel side can be bent outward.

According to the present invention, it is possible to provide a laminate which is capable of suppressing the generation of air bubbles and which has excellent adhesive strength in a high-temperature environment even when the front panel side is bent to the outside.

Drawings

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 diagram illustrating a method of the bending test.

Fig. 4 is a sectional view schematically showing a method for producing a laminate according to the present invention.

Detailed Description

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

< laminate >

Fig. 1 is a schematic cross-sectional view of a laminate according to an embodiment of the present invention. The laminate 100 includes a front panel 101, a1 st adhesive layer 102, a polarizer layer 103, a2 nd adhesive layer 104, and a back panel 105 in this order. The 1 st adhesive layer 102 is formed of a1 st adhesive composition, and the 2 nd adhesive layer 104 is formed of a2 nd adhesive composition. Hereinafter, the 1 st adhesive layer 102 and the 2 nd adhesive layer 104 may be collectively referred to as an adhesive layer.

The thickness of the laminate 100 is not particularly limited, and is, for example, 50 to 4000 μm, preferably 100 to 2000 μm, and more preferably 150 to 1000 μm, since it varies depending on the functions required for the laminate, the use of the laminate, and the like.

The shape of the laminate 100 in plan view may be, for example, a square shape, preferably a square shape having long sides and short sides, and more preferably a rectangle. When the shape of the laminate 100 in the plane direction is a rectangle, the length of the long side may be, for example, 10mm to 1400mm, and preferably 50mm to 600 mm. The length of the short side is, for example, 5mm to 800mm, preferably 30mm to 500mm, and more preferably 50mm to 300 mm. Each layer constituting the laminate may be subjected to a corner rounding process, or an end cutting process or a hole forming process.

The laminate 100 can be used for a display device or the like, for example. The display device is not particularly limited, and examples thereof include an organic electroluminescence (organic EL) display device, an inorganic electroluminescence (inorganic EL) display device, a liquid crystal display device, and an electroluminescence display device. The display device may have a touch panel function.

[ Properties of adhesive layer ]

In the laminate 100, if the thermal decomposition mass reduction rate of the 1 st pressure-sensitive adhesive layer 102 is R1 [% ], and the thermal decomposition mass reduction rate of the 2 nd pressure-sensitive adhesive layer 104 is R2 [% ], the following relational expression (1) is satisfied:

R1≤R2 (1)，

more preferably, the following relational expression (1') is satisfied:

R1＜R2 (1’)。

the thermal decomposition mass reduction rate [% ] of the pressure-sensitive adhesive layer differs depending on the composition of the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer, and if the composition of the pressure-sensitive adhesive composition is the same, it can be said that the thermal decomposition mass reduction rate is also the same. Therefore, even if the 1 st pressure-sensitive adhesive layer 102 and the 2 nd pressure-sensitive adhesive layer 104 were not directly measured, the thermal decomposition mass reduction rate R1 [% ] of the 1 st pressure-sensitive adhesive layer 102 and the thermal decomposition mass reduction rate R2 [% ] of the 2 nd pressure-sensitive adhesive layer 104 could be obtained by measuring the pressure-sensitive adhesive layers formed using the same pressure-sensitive adhesive composition. The thermal decomposition mass reduction rate R1 [% ] of the 1 st pressure-sensitive adhesive layer 104 and the thermal decomposition mass reduction rate R2 [% ] of the 2 nd pressure-sensitive adhesive layer 104 can be measured according to the measurement methods described in the section of example below.

If the thermal decomposition mass reduction rate of the 1 st adhesive layer 102 is set to R1 [% ], and the thermal decomposition mass reduction rate of the 2 nd adhesive layer 104 is set to R2 [% ], the following relational expressions (2) and (3) are satisfied:

10≤R1≤20 (2)

10≤R2≤20 (3)，

the following relational expressions (2a) and (3a) are preferably satisfied:

11≤R1≤19 (2a)

11≤R2≤19 (3a)，

more preferably, the following relational expressions (2b) and (3b) are satisfied:

11≤R1≤14 (2b)

13≤R2≤19 (3b)。

the laminate 100 can be bent with the front panel 101 side facing outward. In a display device including a laminate, if the front panel side is bent to the outside, air bubbles may be generated in the pressure-sensitive adhesive layer. The generation of such bubbles is particularly remarkable in the adhesive layer on the side away from the front panel, i.e., the 2 nd adhesive layer 104 in the laminate 100. As a result of studies by the present inventors, it was found that when the thermal decomposition mass reduction rates of the 1 st pressure-sensitive adhesive layer 102 and the 2 nd pressure-sensitive adhesive layer 104 satisfy the relational expressions (1), (2), and (3), bubbles generated in the pressure-sensitive adhesive layer in the laminate 100 can be suppressed even when the front panel 101 side is made to be the outer side and the bending is performed in a normal temperature environment, and the performance of the pressure-sensitive adhesive layer can be maintained even in a high temperature environment. More specifically, even when the laminate 100 is repeatedly bent 2 ten thousand times so that the inner surface of the laminate 100 has a bending radius of 3mm, bubbles generated in the pressure-sensitive adhesive layer in the laminate 100 can be suppressed (hereinafter, the laminate is also referred to as having excellent "room-temperature bendability"). The room temperature flexibility can be evaluated according to the evaluation methods described in the section of examples described later. The laminate 100 can be bent with the front panel side being the inner side. The display device to which the laminate 100 is applied can be used as a flexible display which can be bent, rolled, or the like. In the present specification, the bending includes a bending form in which a curved surface is formed at a bent portion, and a bending radius of an inner surface of the bending is not particularly limited. In addition, the bending also includes bending in which the bending angle of the inner surface is greater than 0 degrees and less than 180 degrees, and folding in which the bending radius of the inner surface is approximately zero or the bending angle of the inner surface is 0 degrees.

Examples of the method for producing the 1 st adhesive composition and the 2 nd adhesive composition so that the 1 st adhesive layer 102 and the 2 nd adhesive layer 104 satisfy the relational expressions (2) and (3) include a method of forming an adhesive layer from the adhesive composition a described later, a method of changing the kind of a monomer forming the (meth) acrylic polymer a described later, a method of adjusting the molecular weight of the (meth) acrylic polymer a described later, and a method of containing a compound having a nitrogen atom and a (meth) acryloyl group.

[ adhesive composition ]

In one embodiment, the 1 st adhesive layer 102 and the 2 nd adhesive layer 104 are formed from 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-curable type or a thermosetting type. In the present specification, "(meth) acrylic polymer" means at least 1 selected from acrylic polymers and methacrylic polymers. The same applies to the term "methyl". When the 1 st adhesive composition and the 2 nd adhesive composition each contain a (meth) acrylic polymer, the (meth) acrylic polymers may be the same or different. Hereinafter, the (meth) acrylic polymer contained in the adhesive composition a is also referred to as a (meth) acrylic polymer a.

The weight average molecular weight (Mw) of the (meth) acrylic polymer a in the pressure-sensitive adhesive layer obtained is preferably 20 to 150 ten thousand, more preferably 30 to 120 ten thousand, from the viewpoint of easily satisfying the relational expression (2) or the relational expression (3).

In the (meth) acrylic polymer contained in the adhesive composition a, the constituent unit derived from the monomer having a reactive functional group is preferably less than 5% by mass based on the total mass of the polymer. Examples of the reactive functional group include a hydroxyl group, a carboxyl group, an amino group, an amide group, and an epoxy group. This improves the flexibility of the pressure-sensitive adhesive layer, and tends to easily suppress the generation of bubbles in the pressure-sensitive adhesive layer at high temperatures. In the (meth) acrylic polymer a, from the viewpoint of suppressing bubbles at the time of bending, the constituent unit derived from the monomer having a reactive functional group is more preferably 0.01% by mass or less based on the total mass of the polymer, and further preferably does not have a constituent unit derived from the monomer having a reactive functional group, and further preferably does not have a hydroxyl group, a carboxyl group, an amino group, an amide group, and an epoxy group.

(1) Active energy ray-curable adhesive composition

When the adhesive composition a is an active energy ray-curable adhesive composition, the (meth) acrylic polymer a contained in the adhesive composition a may contain a constituent unit derived from a (meth) acrylic monomer having a linear or branched alkyl group having 1 to 24 carbon atoms. Examples of the (meth) acrylic monomer having a linear or branched alkyl group having 1 to 24 carbon atoms include alkyl (meth) acrylates, such as butyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, isooctyl (meth) acrylate, isodecyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isobornyl (meth) acrylate. The (meth) acrylic polymer a may be a polymer or copolymer containing 1 or 2 or more of the above-mentioned alkyl (meth) acrylates as monomers. The content of the (meth) acrylic polymer a in the pressure-sensitive adhesive composition a may be, for example, 50 to 100 mass%, preferably 80 to 99.5 mass%, and more preferably 90 to 99 mass% with respect to 100 parts by mass of the solid content of the pressure-sensitive adhesive composition a.

The weight average molecular weight (Mw) of the (meth) acrylic polymer a may be, for example, 20 to 80 ten thousand, and is preferably 30 to 70 ten thousand from the viewpoint of suppressing bubbles at the time of bending. The weight average molecular weight (Mw) can be measured according to the measurement method described in the section of examples described later.

The adhesive composition a may contain 1 or 2 or more (meth) acrylic polymers a. The pressure-sensitive adhesive composition a may contain only the (meth) acrylic polymer a as a constituent component thereof, or may further contain a crosslinking agent. Examples of the crosslinking agent include metal ions having a valence of 2 or more which form a metal carboxylate with a carboxyl group; polyamine compounds forming amide bonds with carboxyl groups; polyepoxy compounds or polyols which form ester bonds with carboxyl groups; polyisocyanate compounds forming an amide bond with a carboxyl group, and the like. Among them, polyisocyanate compounds are preferable. When the pressure-sensitive 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, more preferably 0.5 part by mass or less, further preferably 0.1 part by mass or less, based on 100 parts by mass of the (meth) acrylic polymer a, and the pressure-sensitive adhesive composition a most preferably does not contain a crosslinking agent.

The active energy ray-curable adhesive composition means an adhesive composition having the following properties: the adhesive sheet is cured by irradiation with an active energy ray such as an ultraviolet ray or an electron beam, has adhesive properties even before irradiation with an active energy ray, can be adhered to an adherend such as a film, and can be cured by irradiation with an active energy ray, thereby adjusting adhesion force and the like.

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

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

Examples of the active energy ray-polymerizable compound include (meth) acrylate monomers having at least 1 (meth) acryloyloxy group in the molecule; a (meth) acrylic compound such as a (meth) acryloyloxy group-containing compound which is obtained by reacting 2 or more kinds of functional group-containing compounds and has at least 2 (meth) acryloyloxy groups in the molecule, e.g., a (meth) acrylate oligomer. The binder composition a may contain 0.1 to 10 parts by mass of the active energy ray-polymerizable compound per 100 parts by mass of the solid content of the binder composition a.

Examples of the photopolymerization initiator include diphenyl (2,4, 6-trimethylbenzoyl) phosphine oxide, benzildimethylketal, and 1-hydroxycyclohexylphenylketone. When the adhesive composition a contains a photopolymerization initiator, 1 or 2 or more species may be contained. When the adhesive composition a contains a photopolymerization initiator, the total content thereof may be, for example, 0.01 to 1.0 part by mass with respect to 100 parts by mass of the solid content of the adhesive composition a.

The adhesive composition a preferably contains a compound having a nitrogen atom and a (meth) acryloyl group. The adhesive composition a may contain only 1 kind of compound having a nitrogen atom and a (meth) acryloyl group, or may contain a plurality of kinds. At least one of the 1 st adhesive composition and the 2 nd adhesive composition is preferably an adhesive composition a containing a compound having a nitrogen atom and a (meth) acryloyl group. The adhesive composition a containing the compound having a nitrogen atom and a (meth) acryloyl group can easily form the 1 st reference adhesive layer and the 2 nd reference adhesive layer satisfying the relational expressions (2) and (3). The adhesive composition a may contain, for example, 0.1 to 10 parts by mass, preferably 1 to 5 parts by mass of a compound having a nitrogen atom and a (meth) acryloyl group per 100 parts by mass of the solid content of the adhesive composition a. The content of the compound having a nitrogen atom and a (meth) acryloyl group can be adjusted so as to satisfy the relational expressions (2) and (3).

The compound having a nitrogen atom and a (meth) acryloyl group preferably has a nitrogen atom bonded to the (meth) acryloyl group, that is, preferably has an amide bond. The compound having a nitrogen atom and a (meth) acryloyl group may be a primary amide, a secondary amide, or a tertiary amide. The compound having a nitrogen atom and a (meth) acryloyl group is not particularly limited, and examples thereof include N-butoxymethylacrylamide, N-dimethylacrylamide, and the like.

The binder composition a may contain additives such as fine particles, beads (resin beads, glass beads, and the like), glass fibers, resins other than the base polymer, adhesion-imparting agents, fillers (metal powders, other inorganic powders, and the like), antioxidants, ultraviolet absorbers, dyes, pigments, colorants, defoaming agents, and anticorrosive agents for imparting light scattering properties. The adhesive composition a preferably does not contain an organic solvent from the viewpoint of preventing the reduction in durability due to the residual solvent.

In the case where the adhesive layer is formed of the adhesive composition a, the adhesive layer may be formed by applying the adhesive composition a onto a substrate. In the case of using an active energy ray-curable pressure-sensitive adhesive composition, a cured product having a desired degree of curing can be produced by irradiating the formed pressure-sensitive adhesive layer with an active energy ray.

The active energy ray is preferably ultraviolet ray. The light source can be low-pressure mercury lamp, medium-pressure mercury lamp, high-pressure mercury lamp, ultrahigh-pressure mercury lamp, chemical lamp, or black lampLight lamps, microwave-excited mercury lamps, metal halide lamps, and the like. The cumulative amount of light of the active energy rays is preferably 0.1J/cm²～1.0J/cm²More preferably 0.2J/cm²～0.9J/cm². The irradiation with active energy rays under such conditions can easily adjust the thermal decomposition mass reduction rate of the pressure-sensitive adhesive layer to a predetermined range.

(2) Heat-curable adhesive composition

When the adhesive composition a is a heat-curable adhesive composition, the (meth) acrylic polymer a preferably contains, as monomer units constituting the polymer, an alkyl (meth) acrylate having an alkyl group and 2 to 20 carbon atoms and a monomer having a reactive functional group in a molecule (reactive functional group-containing monomer).

The (meth) acrylic polymer A can exhibit preferable adhesiveness by containing an alkyl (meth) acrylate having an alkyl group and 2 to 20 carbon atoms as a monomer unit constituting the polymer. The alkyl (meth) acrylate having an alkyl group with 2 to 20 carbon atoms is preferably an alkyl (meth) acrylate having a glass transition temperature (Tg) of-40 ℃ or lower (hereinafter, may be referred to as "low Tg alkyl acrylate") as a homopolymer. By containing the low Tg alkyl acrylate as a constituent monomer unit, flexibility of the pressure-sensitive adhesive layer is improved, and generation of bubbles during bending tends to be easily suppressed.

Examples of the low Tg alkyl acrylate include n-butyl acrylate (Tg of-55 ℃ C.), n-octyl acrylate (Tg of-65 ℃ C.), isooctyl acrylate (Tg of-58 ℃ C.), 2-ethylhexyl acrylate (Tg of-70 ℃ C.), isononyl acrylate (Tg of-58 ℃ C.), isodecyl acrylate (Tg of-60 ℃ C.), isodecyl methacrylate (Tg of-41 ℃ C.), n-lauryl methacrylate (Tg of-65 ℃ C.), tridecyl acrylate (Tg of-55 ℃ C.), and tridecyl methacrylate (Tg of-40 ℃ C.). Among them, the low Tg alkyl acrylate of the homopolymer is more preferably a low Tg alkyl acrylate having a Tg of-45 ℃ or less, particularly preferably a low Tg alkyl acrylate having a Tg of-50 ℃ or less, from the viewpoint of easily satisfying the relational expression (2) or the relational expression (3). Specifically, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferable. These may be used alone, or 2 or more of them may be used in combination.

The (meth) acrylic polymer a preferably contains the low Tg alkyl acrylate in an amount of 85 mass% or more, more preferably 90 mass% or more, and still more preferably 95 mass% or more, in terms of the lower limit of the amount of the monomer units constituting the polymer. If the content is within such a range, the pressure-sensitive adhesive layer obtained easily satisfies the relational expression (2) or the relational expression (3).

The low Tg alkyl acrylate is preferably contained in the (meth) acrylic polymer a in an amount of 99.9 mass% or less, more preferably 99.5 mass% or less, and still more preferably 99 mass% or less, as the upper limit of the monomer unit constituting the polymer. By containing 99.9 mass% or less of the low Tg alkyl acrylate, an appropriate amount of other monomer components (particularly, a monomer having a reactive functional group) 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 to the above range, the content of a monomer having a glass transition temperature (Tg) exceeding 0 ℃ as a homopolymer (hereinafter, may be referred to as "hard monomer") is preferably reduced as much as possible in the (meth) acrylic polymer a. Specifically, in the (meth) acrylic polymer a, the content of the hard monomer as a monomer unit constituting the polymer is preferably 15% by mass or less, more preferably 10% by mass or less, and further preferably 5% by mass or less, as the upper limit value. The hard monomer also includes a reactive functional group-containing monomer described later.

Examples of the hard monomer include methyl acrylate (Tg of 10 ℃ C.), methyl methacrylate (Tg of 105 ℃ C.), ethyl methacrylate (Tg of 65 ℃ C.), n-butyl methacrylate (Tg of 20 ℃ C.), isobutyl methacrylate (Tg of 48 ℃ C.), tert-butyl methacrylate (Tg of 107 ℃ C.), n-stearyl acrylate (Tg of 30 ℃ C.), n-stearyl methacrylate (Tg of 38 ℃ C.), cyclohexyl acrylate (Tg of 15 ℃ C.), cyclohexyl methacrylate (Tg of 66 ℃ C.), phenoxyethyl acrylate (Tg of 5 ℃ C.), phenoxyethyl methacrylate (Tg of 54 ℃ C.), benzyl methacrylate (Tg of 54 ℃ C.), isobornyl acrylate (Tg of 94 ℃ C.), isobornyl methacrylate (Tg of 180 ℃ C.), acryloylmorpholine (Tg of 145 ℃ C.), adamantyl acrylate (Tg of 115 ℃ C.), and so forth, Acrylic monomers such as adamantyl methacrylate (Tg of 141 ℃ C.), acrylic acid (Tg of 103 ℃ C.), dimethylacrylamide (Tg of 89 ℃ C.), acrylamide (Tg of 165 ℃ C.), vinyl acetate (Tg of 32 ℃ C.), styrene (Tg of 80 ℃ C.), and the like.

The (meth) acrylic polymer a contains a reactive functional group-containing monomer as a monomer unit constituting the polymer, and thus forms a crosslinked structure (three-dimensional network structure) by reacting a thermal crosslinking agent described later with the reactive functional group derived from the reactive functional group-containing monomer through the reactive functional group, thereby obtaining an adhesive having a desired cohesive force.

Examples of the reactive functional group-containing monomer contained as a monomer unit constituting the (meth) acrylic polymer a include a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), and a monomer having an amino group in the molecule (amino group-containing monomer). Among these, monomers having a glass transition temperature (Tg) of 0 ℃ or lower are more preferable, and hydroxyl group-containing monomers are particularly preferable.

Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Among them, at least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate and 4-hydroxybutyl acrylate is preferable from the viewpoint of the glass transition temperature (Tg), the reactivity of the hydroxyl group in the obtained (meth) acrylic polymer a with a thermal crosslinking agent and the copolymerizability with other monomers. These may be used alone, or 2 or more of them may be used in combination.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These may be used alone, or 2 or more of them may be used in combination.

Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, n-butylaminoethyl (meth) acrylate, and the like. These may be used alone, or 2 or more of them may be used in combination.

The (meth) acrylic polymer a preferably contains the reactive functional group-containing monomer in an amount of 0.1 mass% or more, particularly preferably 0.5 mass% or more, and more preferably 1 mass% or more, as the lower limit of the monomer unit constituting the polymer. The content of the above-mentioned content is preferably 10% by mass or less, particularly preferably 8% by mass or less, and further preferably less than 5% by mass. If the (meth) acrylic polymer a contains a reactive functional group-containing monomer, particularly a hydroxyl group-containing monomer, as a monomer unit in the above-mentioned amount, the obtained pressure-sensitive adhesive layer easily satisfies the relational expression (2) or the relational expression (3).

In the (meth) acrylic polymer a, as a monomer unit constituting the polymer, a carboxyl group-containing monomer, particularly acrylic acid, which is also a hard monomer, may not be contained. Since the carboxyl group is an acid component, since the carboxyl group-containing monomer is not contained, even when there are components that cause troubles due to an acid, for example, a transparent conductive film such as tin-doped indium oxide (ITO), a metal film, a metal mesh, or the like in the object to which the adhesive is attached, it is possible to suppress the troubles (corrosion, change in resistance value, or the like) caused by an acid.

The (meth) acrylic polymer a may contain other monomers as the monomer unit constituting the polymer, if necessary. As the other monomer, a monomer containing no reactive functional group is also preferable in order not to hinder the action of the reactive functional group-containing monomer. Examples of the other monomer include, in addition to alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, monomers having a glass transition temperature (Tg) of more than-40 ℃ and not more than 0 ℃ as a homopolymer (hereinafter, sometimes referred to as "medium Tg alkyl acrylate"), and the medium Tg alkyl acrylates include, for example, ethyl acrylate (Tg of-20 ℃), isobutyl acrylate (Tg of-26 ℃), 2-ethylhexyl methacrylate (Tg of-10 ℃), n-lauryl acrylate (Tg of-23 ℃), isostearyl acrylate (Tg of-18 ℃) and the like, and these may be used alone or in combination of 2 or more.

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

The lower limit of the weight average molecular weight of the (meth) acrylic polymer a is preferably 20 ten thousand or more, particularly preferably 30 ten thousand or more, and more preferably 40 ten thousand or more. When the lower limit of the weight average molecular weight of the (meth) acrylic polymer a is not less than the above range, troubles such as bleeding out of the adhesive can be suppressed. The weight average molecular weight in the present specification is a value in terms of standard polystyrene measured by a Gel Permeation Chromatography (GPC) method.

The upper limit of the weight average molecular weight of the (meth) acrylic polymer a is preferably 150 ten thousand or less, particularly preferably 135 ten thousand or less, and more preferably 120 ten thousand 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 obtained pressure-sensitive adhesive layer easily satisfies the relational expression (2) or the relational expression (3).

In the adhesive composition a, 1 kind of the (meth) acrylic polymer a may be used alone, or 2 or more kinds may be used in combination.

When the adhesive composition A containing a thermal crosslinking agent is heated, the thermal crosslinking agent crosslinks the (meth) acrylic polymer A to form a three-dimensional network structure. This improves the cohesive force of the resulting pressure-sensitive adhesive, and the resulting pressure-sensitive adhesive layer easily satisfies the relational expression (2) or the relational expression (3).

The thermal crosslinking agent may be any thermal crosslinking agent that reacts with the reactive group of the (meth) acrylic polymer a, and examples thereof include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, amine-based crosslinking agents, and the like,An oxazoline-based crosslinking agent, a metal alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, an ammonium salt-based crosslinking agent, and the like. Among the above, when the reactive group of the (meth) acrylic polymer a is a hydroxyl group, an isocyanate-based crosslinking agent having excellent reactivity with the hydroxyl group is preferably used. The thermal crosslinking agent may be used alone in 1 kind, or in combination of 2 or more kinds.

The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and biuret or isocyanurate adducts thereof, and adducts thereof as reaction products with low-molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane and castor oil. Among them, trimethylolpropane-modified aromatic polyisocyanates are preferable from the viewpoint of reactivity with hydroxyl groups, and trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are particularly preferable.

Examples of the epoxy-based crosslinking agent include 1, 3-bis (N, N-diglycidylaminomethyl) cyclohexane, N' -tetraglycidylmethylenem-xylylenediamine, ethylene glycol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, and diglycidylamine.

The content of the thermal crosslinking agent in the adhesive composition a is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, and still more preferably 0.1 mass% or more, with respect to 100 mass% of the (meth) acrylic polymer a. 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 obtained adhesive layer easily satisfies the relational expression (2) or the relational expression (3).

The adhesive composition a preferably contains the silane coupling agent. This improves the adhesion between the pressure-sensitive adhesive layer obtained and each member in the flexible laminate as an adherend, and further improves the durability against bending.

The silane coupling agent is preferably an organosilicon compound having at least 1 alkoxysilyl group in the molecule, and has good compatibility with the (meth) acrylic polymer a and light transmittance.

Examples of the silane coupling agent include silicon compounds containing a polymerizable unsaturated group such as vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane and the like; silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane and 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane; mercapto group-containing silicon compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, etc.; amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane; 3-chloropropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, or a condensate of at least one of these with an alkyl-containing silicon compound such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, or ethyltrimethoxysilane. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

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 or more, based on 100% by mass of the (meth) acrylic polymer a. 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 range, the obtained pressure-sensitive adhesive layer has more preferable adhesion to each member in the flexible laminate as an adherend.

The adhesive composition a may contain the above-mentioned various additives as required. The additive constituting the adhesive composition a does not contain a polymerization solvent or a diluting solvent.

The (meth) acrylic polymer a can be produced by polymerizing a mixture of monomers constituting the polymer by a general 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 needed. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and 2 or more kinds thereof may be used in combination.

The polymerization initiator may be an azo compound, an organic peroxide, or the like, and 2 or more kinds may be used in combination. Examples of the azo compound include 2,2 ' -azobisisobutyronitrile, 2 ' -azobis (2-methylbutyronitrile), 1 ' -azobis (cyclohexane 1-carbonitrile), 2 ' -azobis (2, 4-dimethylvaleronitrile), 2 ' -azobis (2, 4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2 ' -azobis (2-methylpropionate), 4 ' -azobis (4-cyanovaleric acid), 2 ' -azobis (2-hydroxymethylpropionitrile), and 2,2 ' -azobis [2- (2-imidazolin-2-yl) propane ].

Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxyethyl) peroxydicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxyvalerate, (3,5, 5-trimethylhexanoyl) peroxide, dipropionylperoxide, and diacetyl peroxide.

In the polymerization step, a chain transfer agent such as 2-mercaptoethanol is added to adjust the weight average molecular weight of the obtained polymer.

After obtaining the (meth) acrylic polymer a, a thermal crosslinking agent, a silane coupling agent, and if necessary, an additive and a diluting solvent are added to a solution of the (meth) acrylic polymer a and sufficiently mixed to obtain a binder composition a (coating solution) diluted with a solvent.

In the case where a solid component is used or a precipitate is generated when the solid component is mixed with another component in an undiluted state, any of the above components may be dissolved or diluted in a diluting solvent alone and then mixed with another component.

Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane and dichloroethane; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; and cellosolve-based solvents such as ethyl cellosolve.

The concentration and viscosity of the coating solution prepared in this manner are not particularly limited as long as the coating solution can be applied, and may be appropriately selected according to the situation. For example, the binder composition A is diluted so that the concentration thereof is 10 to 60 mass%. The addition of a diluting solvent or the like is not an essential condition when obtaining a coating solution, and the diluting solvent may not be added if the adhesive composition a has a viscosity capable of being coated or the like. In this case, the pressure-sensitive adhesive composition a is a coating solution in which the polymerization solvent of the (meth) acrylic polymer a is directly used as a dilution solvent.

A preferable pressure-sensitive adhesive as the pressure-sensitive adhesive of the present embodiment is a pressure-sensitive adhesive composition a obtained by crosslinking. Crosslinking of the adhesive composition a may be performed by heat treatment. The heat treatment may also be used as a drying treatment when a diluent solvent or the like is volatilized from a coating film of the binder composition a applied to a desired object.

The heating temperature of the heating treatment is preferably 50 to 150 ℃, and more preferably 70 to 120 ℃. The heating time is preferably 10 seconds to 10 minutes, and 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 (e.g., 23 ℃ C., 50% RH). In the case where the curing period is required, the adhesive is formed after the curing period, and in the case where the curing period is not required, the adhesive is formed after the heat treatment is completed.

By the heat treatment (and curing), the (meth) acrylic polymer a is sufficiently crosslinked via the crosslinking agent to form a crosslinked structure, thereby obtaining an adhesive. The pressure-sensitive adhesive easily satisfies the relational expression (2) or the relational expression (3) with respect to the pressure-sensitive adhesive layer obtained.

The adhesive sheet of the present invention comprises an adhesive layer formed from the adhesive composition a of the present invention described above. The adhesive layer may be formed by applying the adhesive composition a to a substrate. When a thermosetting adhesive composition is used as the adhesive composition a, the adhesive layer formed is subjected to heat treatment (and curing) to produce a cured product having a desired degree of curing. The conditions of the heat treatment and the aging are as described above.

The substrate may be a release film subjected to a release treatment. The pressure-sensitive adhesive sheet can be produced by forming a layer made of a pressure-sensitive adhesive on a release film in a sheet form in advance, and further laminating another release film on the pressure-sensitive adhesive layer.

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

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

[ front panel ]

The front panel 101 is not limited in material and thickness as long as it is a plate-like body that can transmit light, and may be composed of only 1 layer, or 2 or more layers. Examples thereof include a plate-like body made of resin (for example, a resin plate, a resin sheet, a resin film, etc.), a plate-like body made of glass (for example, a glass plate, a glass film, etc.), and a touch sensor panel described later. The front panel may constitute the outermost surface of the display device.

The thickness of the front plate 101 may be, for example, 10 to 500. mu.m, preferably 30 to 200. mu.m, and more preferably 50 to 100. mu.m. In the present invention, the thickness of each layer can be measured by the thickness measurement method described in the examples described below.

When the front panel 101 is a resin plate-like body, the resin plate-like body is not limited as long as light can be transmitted therethrough. Examples of the resin constituting the plate-like body made of a resin such as a resin film include films made of polymers such as triacetyl cellulose, cellulose acetate butyrate, ethylene-vinyl acetate copolymer, propionyl cellulose, butyryl cellulose, levulinyl cellulose, polyester, polystyrene, polyamide, polyetherimide, poly (meth) acrylic acid, polyimide, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polyethersulfone, polymethylmethacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, and polyamideimide. These polymers may be used alone or in combination of 2 or more. From the viewpoint of improving strength and transparency, a resin film made of a polymer such as polyimide, polyamide, polyamideimide, or the like is preferable.

From the viewpoint of enhancing the hardness, the front panel 101 is preferably a film in which a hard coat layer is provided on at least one surface of a base film. As the base film, a film formed of the above resin can be used. The hard coat layer may be formed on one surface of the substrate film or on both surfaces. By providing the hard coat layer, a resin film having improved hardness and scratch resistance can be produced. The hard coat layer is a cured layer of, for example, an ultraviolet curable resin. Examples of the ultraviolet curable resin include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. To increase the hardness, the hard coating may contain additives. The additive is not limited, and examples thereof include inorganic fine particles, organic fine particles, and a mixture thereof.

When the front panel 101 is a glass plate, a strengthened glass for display is preferably used as the glass plate. The thickness of the glass plate may be, for example, 10 to 1000. mu.m. By using the glass plate, the front panel 101 having excellent mechanical strength and surface hardness can be configured.

When the laminate 100 is used in a display device, the front panel 101 may be a front panel having a function of protecting the front surface (screen) of the display device (a function as a window film), a function as a touch sensor, a blue light cut-off function, a viewing angle adjustment function, and the like.

[1 st adhesive layer ]

The 1 st adhesive layer 102 is a layer interposed between the front panel 101 and the polarizer layer 103 and bonded to each other, and may be a layer made of, for example, an adhesive or a bonding agent, or a layer obtained by subjecting the layer to some treatment. The 1 st adhesive layer may be an adhesive layer disposed closest to the front panel among the adhesive layers constituting the laminate. Adhesives are also known as pressure sensitive adhesives. In the present specification, the "adhesive" refers to an adhesive other than an adhesive (pressure-sensitive adhesive), and is clearly distinguished from an adhesive. The 1 st adhesive layer 102 may be composed of 1 layer, or may be composed of 2 or more layers, preferably 1 layer.

The 1 st adhesive layer 20 may be formed directly from the adhesive composition or using an adhesive sheet having an adhesive layer formed using the adhesive composition. The adhesive composition may be formed from adhesive composition a as described above.

The thickness of the 1 st pressure-sensitive adhesive layer 102 is, for example, preferably 3 μm to 100 μm, more preferably 5 μm to 50 μm, and may be 20 μm or more.

[ polarizer layer ]

Examples of the polarizer layer 103 include a stretched film or a stretched layer having a dichroic dye adsorbed thereon, and a layer obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound. As the dichroic dye, specifically, iodine or a dichroic organic dye can be used. The dichroic organic dye includes a dichroic direct dye composed of a bisazo compound such as c.i. direct RED (c.i. direct RED)39, and a dichroic direct dye composed of a compound such as a trisazo compound or a tetrazo compound.

Examples of the polarizer layer obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound include a polarizer layer containing a cured product of a polymerizable liquid crystal compound, such as a layer obtained by applying and curing a composition containing a dichroic dye having liquid crystallinity or a composition containing a dichroic dye and a polymerizable liquid crystal.

The polarizing layer obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound is preferable to the stretched film or the stretched layer having the dichroic dye adsorbed thereon because the polarizing layer has no limitation in the bending direction.

[ polarizer layer being stretched film or stretched layer ]

The polarizer layer as a stretched film having a dichroic dye adsorbed thereon can be generally produced through the following steps: a step of uniaxially stretching a polyvinyl alcohol resin film; a step of adsorbing a dichroic dye by dyeing a polyvinyl alcohol resin film with the dichroic dye; treating the polyvinyl alcohol resin film having the dichroic dye adsorbed thereon with an aqueous boric acid solution; and a step of washing the substrate with water after the treatment with the aqueous boric acid solution.

The thickness of the polarizer layer 103 is, for example, 2 μm to 40 μm. The thickness of the polarizer layer 103 may be 5 μm or more, 20 μm or less, further 15 μm or less, and further 10 μm or less.

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

The saponification degree of the polyvinyl alcohol resin is usually about 85 mol% to 100 mol%, and preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The polymerization degree of the polyvinyl alcohol resin is usually 1000 to 10000, preferably 1500 to 5000.

The polarizer layer as the stretched layer having the dichroic dye adsorbed thereon can be generally produced through the following steps: a step of applying a coating liquid containing the polyvinyl alcohol resin onto a base film; a step of uniaxially stretching the obtained laminated film; a step of dyeing the polyvinyl alcohol resin layer of the uniaxially stretched laminated film with a dichroic dye to adsorb the dichroic dye to produce a polarizer; treating the film having the dichroic dye adsorbed thereon with an aqueous boric acid solution; and a step of washing the substrate with water after the treatment with the aqueous boric acid solution.

The substrate film may be peeled off from the polarizer layer as necessary. The material and thickness of the base film may be the same as those of the thermoplastic resin film described later.

The polarizer layer as the stretched film or the stretched layer may be assembled in a laminate in a form in which a thermoplastic resin film is bonded to one surface or both surfaces thereof. The thermoplastic resin film can function as a protective film or a retardation film for the polarizer layer 103. The thermoplastic resin film may be formed of a polyolefin resin such as a chain polyolefin resin (e.g., a polypropylene resin) or a cyclic polyolefin resin (e.g., a norbornene resin); cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; a polycarbonate-based resin; (meth) acrylic resins; or a mixture thereof.

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

[ polarizer layer obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound ]

Examples of the polarizer layer obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound include a polarizer layer containing a cured product of a polymerizable liquid crystal compound, such as a layer obtained by applying and curing a composition containing a liquid crystal-polymerizable dichroic dye or a composition containing a dichroic dye and a polymerizable liquid crystal to a base film.

The substrate film may be peeled off from the polarizer layer as necessary. The material and thickness of the base film may be the same as those of the thermoplastic resin film described above. The polarizer layer may be provided with an orientation film. The alignment film may be peeled off.

The polarizer layer obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound may be incorporated in the optical laminate in a form in which a thermoplastic resin film is bonded to one or both surfaces thereof. As the thermoplastic resin film, the same thermoplastic resin film as that usable for the stretched film or the polarizer layer of the stretched layer can be used. The thermoplastic resin film may be bonded to the polarizer layer using an adhesive layer, for example.

The polarizer layer obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound may have an Overcoat (OC) layer formed on one or both surfaces thereof as a protective layer. Examples thereof include photocurable resins and water-soluble polymers. Examples of the photocurable resin include a (meth) acrylic resin, a urethane resin, a (meth) acrylic urethane resin, an epoxy resin, and a silicone resin. Examples of the water-soluble polymer include poly (meth) acrylamide polymers; vinyl alcohol polymers such as polyvinyl alcohol and ethylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, (meth) acrylic acid or anhydride thereof-vinyl alcohol copolymers; a carboxyvinyl polymer; polyvinylpyrrolidone; starches; sodium alginate; polyethylene oxide polymers, and the like. The thickness of the OC layer is preferably 20 μm or less, more preferably 15 μm or less, still more preferably 10 μm or less, and may be 5 μm or less, and may be 0.05 μm or more, and may be 0.5 μm or more.

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

[2 nd adhesive layer ]

The 2 nd adhesive layer 104 is an adhesive layer disposed between the polarizer layer 103 and the back surface plate 105. The 2 nd adhesive layer may be an adhesive layer disposed closest to the back surface plate among the adhesive layers constituting the laminate. The 2 nd adhesive layer 104 may be 1 layer, or may be composed of 2 or more layers, and preferably 1 layer.

The composition and blending components of the pressure-sensitive adhesive composition constituting the 2 nd pressure-sensitive adhesive layer 104, the type of the pressure-sensitive adhesive composition (whether it is active energy ray-curable or thermosetting, etc.), additives that can be blended in the pressure-sensitive adhesive composition, the method for producing the 2 nd pressure-sensitive adhesive layer, and the thickness of the 2 nd pressure-sensitive adhesive layer are the same as those described in the above description of the 1 st pressure-sensitive adhesive layer 102.

The 2 nd adhesive layer 104 may be the same as or different from the 1 st adhesive layer 102 in composition, blending components, thickness, and the like of the adhesive composition.

[ Back Panel ]

As the back plate 105, a plate-like body that can transmit light, a component used in a general display device, or the like can be used.

The thickness of back plate 105 may be, for example, 5 μm to 2000 μm, preferably 10 μm to 1000 μm, and more preferably 15 μm to 500 μm.

The plate-like body used for rear plate 105 may be formed of only 1 layer or 2 or more layers, and the plate-like body exemplified for the plate-like body described in front plate 101 may be used.

Examples of the constituent elements used in a typical display device used for the back panel 105 include a spacer, a touch sensor panel, and an organic EL display element. Examples of the order of stacking the components in the display device include a front panel, a circularly polarizing plate, a spacer, a front panel, a circularly polarizing plate, an organic EL display element, a front panel, a circularly polarizing plate, a touch sensor panel, an organic EL display element, a front panel, a touch sensor panel, a circularly polarizing plate, and an organic EL display element.

(touch sensor panel)

The touch sensor panel is not limited to a detection method as long as it is a sensor capable of detecting a touched position, and examples thereof include touch sensor panels of a resistive film method, a capacitive coupling method, an optical sensor method, an ultrasonic wave method, an electromagnetic induction coupling method, a surface acoustic wave method, and the like. From the viewpoint of low cost, a touch sensor panel of a resistive film type or a capacitive coupling type can be preferably used.

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

An example of a capacitive coupling type touch sensor panel includes a substrate, a position detection transparent electrode provided on the entire surface of the substrate, and a touch position detection circuit. In an image display device provided with a capacitive coupling type touch sensor panel, if the front surface of the front panel is touched, the transparent electrode is grounded via the capacitance of a 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 to 2000 μm, or 5 to 100 μm.

[ phase difference layer ]

The laminate 100 may further include 1 or 2 or more retardation layers. The phase difference layer is typically disposed between the polarizer layer 103 and the back panel 105. The retardation layer may be laminated on the 1 st pressure-sensitive adhesive layer 102 or the 2 nd pressure-sensitive adhesive layer 104, or may be laminated on another layer (including another retardation layer) via a layer (hereinafter, also referred to as a laminating layer) made of a pressure-sensitive adhesive or an adhesive other than these layers.

[ adhesive layer ]

The laminating layer is a layer disposed between the 1 st adhesive layer 102 and the 2 nd adhesive layer 104, and is a layer made of an adhesive or an adhesive. The adhesive constituting the laminating layer may be the same adhesive as exemplified for the adhesive composition constituting the 1 st adhesive layer 102 or the 2 nd adhesive layer, or may be another adhesive such as a (meth) acrylic adhesive, a styrene-based adhesive, a silicone-based adhesive, a rubber-based adhesive, a urethane-based adhesive, a polyester-based adhesive, an epoxy-based copolymer adhesive, or the like.

The adhesive constituting the adhesive layer may be formed by combining 1 or 2 or more kinds of water-based adhesives, active energy ray-curable adhesives, pressure-sensitive adhesives, and the like. Examples of the aqueous adhesive include a polyvinyl alcohol resin aqueous solution and an aqueous two-pack type urethane emulsion adhesive. The active energy ray-curable adhesive is an adhesive that is cured by irradiation with an active energy ray such as ultraviolet ray, and examples thereof include an adhesive containing a polymerizable compound and a photopolymerization initiator, an adhesive containing a photoreactive resin, and an adhesive containing a binder resin and a photoreactive crosslinking agent. Examples of the polymerizable compound include photopolymerizable monomers such as a photocurable epoxy monomer, a photocurable acrylic monomer, and a photocurable urethane monomer, and oligomers derived from these monomers. Examples of the photopolymerization initiator include photopolymerization initiators containing active species that generate neutral radicals, anionic radicals, cationic radicals, and the like by irradiation with active energy rays such as ultraviolet rays.

The thickness of the adhesive layer may be, for example, 1 μm or more, preferably 1 to 25 μm, more preferably 2 to 15 μm, and still more preferably 2.5 to 5 μm.

The laminate 200 shown in fig. 2 includes a front plate 101, a1 st adhesive layer 102, a polarizer layer 103, a bonding layer 108, and a back plate 105, and further includes a1 st retardation layer 106, a bonding layer 109, a2 nd retardation layer 107, and a2 nd adhesive layer 104.

Examples of the retardation layer include a positive a plate and a positive C plate such as a λ/4 plate and a λ/2 plate.

The retardation layer may be, for example, a retardation film that can be formed of the thermoplastic resin film, or a layer obtained 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 preferable.

The thickness of the retardation film may be the same as that of the thermoplastic resin film described above. The thickness of the retardation layer obtained by curing the polymerizable liquid crystal compound is, for example, 0.1 to 10 μm, preferably 0.5 to 8 μm, and more preferably 1 to 6 μm.

The retardation layer obtained by curing the polymerizable liquid crystal compound can be formed by applying a composition containing the polymerizable liquid crystal compound to a substrate film and curing the composition. An alignment layer may also be formed between the substrate film and the coating layer. The material and thickness of the base film may be the same as those of the thermoplastic resin film described above.

The retardation layer obtained by curing the polymerizable liquid crystal compound may be incorporated in the laminate 100 in a form having an alignment layer and/or a substrate film. The back panel 105 may also be a substrate film coated with the above composition.

As described above, the adhesive or the adhesive may be used for the adhesion layer 108. The binder may be the binder composition a described above.

As the adhesive, an aqueous adhesive or an active energy ray-curable adhesive can be used. Examples of the aqueous adhesive include an adhesive composed of a polyvinyl alcohol resin aqueous solution, and an aqueous two-pack type urethane emulsion adhesive.

The active energy ray-curable adhesive is an adhesive that is cured by irradiation with an active energy ray such as ultraviolet ray, and examples thereof include an adhesive containing a polymerizable compound and a photopolymerization initiator, an adhesive containing a photoreactive resin, and an adhesive containing a binder resin and a photoreactive crosslinking agent.

Examples of the polymerizable compound include photopolymerizable monomers such as a photocurable epoxy monomer, a photocurable (meth) acrylic monomer, and a photocurable urethane monomer, and oligomers derived from a photopolymerizable monomer.

Examples of the photopolymerization initiator include photopolymerization initiators containing active species that generate 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, an active energy ray-curable adhesive containing a photocurable epoxy monomer and a photocationic polymerization initiator can be preferably used.

[ method for producing laminate ]

The laminate 100 can be manufactured by a method including the following steps: the layers constituting the laminate 100 are bonded to each other via an adhesive layer or further via an adhesive layer. When the layers are bonded to each other via an adhesive layer or an adhesive layer, one or both of the bonding surfaces are preferably subjected to a surface activation treatment such as corona treatment in order to improve the adhesion.

The polarizer layer 103 may be formed directly on a thermoplastic resin film or a base film, which may be incorporated in the laminate 100, or may be separated from the polarizer layer 103 without being a constituent of the laminate.

< display device >

The display device of the present invention includes the laminate 100 of the present invention described above. The display device is not particularly limited, and examples thereof include image display devices such as an organic EL display device, an inorganic EL display device, a liquid crystal display device, and an electroluminescence display device. The display device may have a touch panel function. The optical laminate is suitable for a flexible display device which can be bent or bent.

In the display device, the optical laminate is disposed on the viewing side of the display element included in the display device such that the front panel faces outward (the side opposite to the display element side, i.e., the viewing side).

The display device of the present invention can be used as a mobile device such as a smart phone or a tablet computer, a television, a digital photo frame, an electronic sign, a measuring instrument, an office machine, a medical machine, a computer machine, or the like.

< adhesive composition >

The adhesive composition of the present invention is preferably the adhesive composition a described above. The adhesive composition of the present invention can be produced by mixing the respective components together by a known method, for example, using a mixer or the like.

< adhesive sheet >

The adhesive sheet of the present invention includes an adhesive layer formed from an adhesive composition containing a (meth) acrylic polymer and a compound having a nitrogen atom and a (meth) acryloyl group, and preferably includes an adhesive layer formed from an adhesive composition a. The adhesive layer may be formed by applying the adhesive composition to a substrate. When an active energy ray-curable pressure-sensitive adhesive composition is used as the pressure-sensitive adhesive composition, a cured product having a desired degree of curing can be obtained by irradiating the pressure-sensitive adhesive layer thus formed with active energy rays. When a thermosetting adhesive composition is used as the adhesive composition, the formed adhesive layer is subjected to heat treatment (and curing), whereby a cured product having a desired degree of curing can be obtained.

The substrate may be a release film subjected to a release treatment. The pressure-sensitive adhesive sheet can be produced by forming a layer made of a pressure-sensitive adhesive on a release film in a sheet form in advance, and further laminating another release film on the pressure-sensitive adhesive layer.

The adhesive layer of the adhesive sheet of the present invention has excellent heat resistance. When the thermal decomposition mass reduction rate of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive layer is R [% ], the following relational expression (4) is preferably satisfied:

10≤R≤20 (4)，

more preferably, the following relational expression (4a) is satisfied:

11≤R≤19 (4a)。

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

Examples

[ adhesive sheet Using Heat-curable adhesive composition ]

[1] Production of adhesive sheet A11

(1) Preparation of (meth) acrylic polymer

A (meth) acrylic polymer was prepared by copolymerizing 54 parts by mass of n-butyl acrylate, 45 parts by mass of 2-ethylhexyl acrylate, and 1 part by mass of 4-hydroxybutyl acrylate. The molecular weight of the (meth) acrylic polymer was measured by the method described later, and the weight average molecular weight (Mw) was 80 ten thousand.

(2) Preparation of adhesive composition

100 parts by mass (solid content equivalent; the same applies hereinafter) of the (meth) acrylic polymer obtained in the above step, 0.25 part by mass of trimethylolpropane-modified xylylene diisocyanate (product name "TD-75" manufactured by Soken chemical Co., Ltd.) as a thermal crosslinking agent, and 0.2 part by mass of 3-glycidoxypropyltrimethoxysilane (product name "KBM 403" manufactured by shin-Etsu chemical Co., Ltd.) as a silane coupling agent were mixed, sufficiently stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the pressure-sensitive adhesive composition. Table 1 shows the respective formulations (solid content equivalent) of the adhesive compositions when the (meth) acrylic polymer is assumed to be 100 parts by mass (solid content equivalent). The abbreviations and the like shown in table 1 have the following meanings.

BA: acrylic acid n-butyl ester

2 EHA: 2-ethylhexyl acrylate

4 HBA: acrylic acid 4-hydroxybutyl ester

(3) Production of adhesive sheet A11

The obtained coating solution of the adhesive composition was applied to a release-treated surface of a light separator (product name "SP-PET 752150" manufactured by Lintec corporation) by a knife coater. Then, the coating layer was heat-treated at 90 ℃ for 1 minute to form a coating layer. Then, the coating layer on the light separator obtained above was bonded to a heavy separator (product name "SP-PET 382120" manufactured by Lintec Co., Ltd.) so that the release-treated surface of the separator was in contact with the coating layer, and the resultant was cured at 23 ℃ and 50% RH for 7 days to produce a pressure-sensitive adhesive sheet A11 having a pressure-sensitive adhesive layer with a thickness of 25 μm, that is, a pressure-sensitive adhesive sheet A11 having a structure of light separator/pressure-sensitive adhesive layer (thickness: 25 μm)/heavy separator. The adhesive layer of the adhesive sheet a11 was referred to as adhesive layer a 11. The measured mass reduction rate of thermal decomposition of the psa sheet a11 is shown in table 1. The thickness and the thermal decomposition mass reduction rate of the pressure-sensitive adhesive layer a11 were measured by the methods described later.

[2] Production of adhesive sheets A12 to A16

(1) Preparation of (meth) acrylic polymer

The weight-average molecular weight (Mw) of the (meth) acrylic polymer shown in table 1 was prepared in the same manner as in the production process of the adhesive sheet a11, with the ratios of the monomers constituting the (meth) acrylic polymer adjusted as shown in table 1.

(2) Preparation of adhesive composition

100 parts by mass of the (meth) acrylic polymer obtained in the above step, trimethylolpropane-modified xylylene diisocyanate (product name "TD-75" from Soken chemical Co., Ltd.) as a thermal crosslinking agent, and 3-glycidoxypropyltrimethoxysilane (product name "KBM 403" from shin-Etsu chemical Co., Ltd.) as a silane coupling agent were mixed in the blending ratio shown in Table 1, sufficiently stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the pressure-sensitive adhesive composition.

(3) Production of adhesive sheets A12 to A16

Using the obtained coating solution of the adhesive composition, adhesive sheets a12 to a16 were produced in the same manner as in the production process of the adhesive sheet a 11. The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets a12 to a16 were referred to as pressure-sensitive adhesive layers a12 to a 16. The thicknesses and the thermal decomposition mass reduction rates of the adhesive sheets a12 to a16 of the adhesive layers a12 to a16 measured by the method described later are shown in table 1.

[ Table 1]

[ adhesive sheet Using active energy ray-curable adhesive composition ]

[1] Production of adhesive sheet A21

(1) Preparation of (meth) acrylic Polymer A21

After a monomer mixture comprising 84.4 mass% of 2-ethylhexyl acrylate (2-EHA) monomer, 15 mass% of Butyl Acrylate (BA) monomer and 0.5 mass% of 2-hydroxyethyl acrylate (2-HEA) monomer was charged into a 1L reactor equipped with a cooling device to allow nitrogen to flow back and facilitate temperature adjustment, nitrogen was refluxed for 1 hour to remove oxygen and then maintained at 80 ℃. After the monomer mixture was uniformly mixed, 0.05 mass% of benzildimethylketal (I-651) and 0.05 mass% of 1-hydroxycyclohexylphenylketone (I-184) as photopolymerization initiators were added. Subsequently, a UV lamp (10mW) was irradiated with the resulting mixture while stirring to produce a (meth) acrylic polymer A21 having a weight-average molecular weight (Mw) of 37 ten thousand.

The proportions of the monomers and components of the acrylic polymer a21 are shown in table 2. The abbreviations and the like shown in table 2 have the following meanings.

2-EHA: 2-ethylhexyl acrylate (Tokyo chemical Co., Ltd., Japan),

BA: butyl acrylate (Tokyo chemical industry Co., Ltd., Japan),

2-HEA: 2-hydroxyethyl acrylate (Tokyo chemical industry Co., Ltd., Japan),

2-HEMA: 2-ethylhexyl methacrylate (Tokyo chemical Co., Ltd., Japan),

LA: lauryl acrylate (Tokyo chemical industry Co., Ltd., Japan),

i-651: benzildimethylketal (photopolymerization initiator, BASF, germany),

i-184: 1-Hydroxycyclohexyl phenyl ketone (photopolymerization initiator, BASF, Germany).

(2) Preparation of adhesive composition

95 mass% (solid content equivalent; the same applies hereinafter) of the (meth) acrylic polymer obtained in the above step, 1 mass% of isodecyl acrylate (IDA, Miwon specialty chemical, korea) and 3 mass% of N-butoxymethylacrylamide (NBMA, tokyo chemical industries co., ltd., japan) as additives, 0.5 mass% of diphenyl (2,4, 6-trimethylbenzoyl) phosphine oxide (TPO, tokyo chemical industries co., ltd., japan) as a photopolymerization initiator, and 0.5 mass% of 1-hydroxycyclohexyl phenyl ketone (I-184, BASF, germany) were mixed, sufficiently stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition. The respective compounding ratios (solid content conversion values) of the pressure-sensitive adhesive compositions are shown in table 3. The abbreviations and the like shown in table 3 have the following meanings.

IDA: isodecyl acrylate (Miwon specialty chemical, Korea)

NBMA: n-butoxymethylacrylamide (NBMA, Tokyo chemical Co., Ltd., Japan)

TPO: diphenyl (2,4, 6-trimethylbenzoyl) phosphine oxide (Tokyo Kasei Kogyo, Japan)

I-184: 1-Hydroxycyclohexylphenylketone (BASF, Germany)

(3) Production of adhesive sheet A21

The obtained coating solution of the adhesive composition was applied to a release-treated surface of a light separator (polyethylene terephthalate film, thickness 38 μm) by a knife coater. Next, the coating layer on the light separator obtained above was bonded to a heavy separator (polyethylene terephthalate film, thickness 38 μm) so that the release-treated surface of the separator was in contact with the coating layer, and UV irradiation (light source: UV-A, irradiation intensity 100 mW/cm)²Cumulative light amount of 0.4J/cm²) To obtain an adhesive sheet a21 having an adhesive layer with a thickness of 25 μm, that is, an adhesive sheet formed of a light separator/adhesive layer (thickness: 25 μm)/heavy separator was used as the adhesive sheet a 21. The adhesive layer of the adhesive sheet a21 was referred to as adhesive layer a 21. The measured mass reduction rate of thermal decomposition of the psa sheet a21 is shown in table 3. The thickness and the thermal decomposition mass reduction rate of the pressure-sensitive adhesive layer a21 were values measured by the methods described later。

[2] Production of adhesive sheets A22 and A23

(1) Preparation of (meth) acrylic polymers A22, A23

The ratio of the monomers constituting the (meth) acrylic polymer was adjusted as shown in table 2, and (meth) acrylic polymers a22 and a23 having the weight average molecular weights (Mw) shown in table 2 were prepared in the same manner as in the production process of the adhesive sheet a 21.

(2) Preparation of adhesive composition

The (meth) acrylic polymer obtained in the above-mentioned step and the additive were mixed at the mixing ratio shown in table 3, sufficiently stirred, and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition.

(3) Production of adhesive sheets A22 and A23

Using the obtained coating solution of the adhesive composition, adhesive sheets a22 and a23 were produced in the same manner as in the production process of the adhesive sheet a 21. The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets a22 and a23 were referred to as pressure-sensitive adhesive layers a22 and a 23. The thicknesses and the thermal decomposition mass reduction rates of the pressure-sensitive adhesive sheets a22 and a23 of the pressure-sensitive adhesive layers a22 and a23, which were measured by the methods described later, are shown in table 3.

[ Table 2]

[ Table 3]

< measurement of weight average molecular weight (Mw) >

The weight average molecular weight (Mw) of the (meth) acrylic polymer was determined as a number average molecular weight (Mn) in terms of polystyrene, and the mobile phase was obtained by the Size Exclusion Chromatography (SEC) described below using tetrahydrofuran.

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

< thickness of layer >

The film thickness was measured using a contact type film thickness measuring apparatus ("MS-5C" manufactured by Nikon K.K.).

The polarizer layer and the alignment film were measured using a laser microscope (OLS 3000, Olympus).

< thermal decomposition Mass reduction Rate >

The adhesive sheet was cut to a width of 25mm x a length of 100 mm. After the release film was removed from the adhesive sheet, the adhesive layer was placed in a tray (pan), and the adhesive layer was heated from room temperature to 200 ℃ at a temperature rising rate of 10 ℃ per minute by a thermogravimetric analyzer (product name: TGA550, manufactured by TA Instrument Co.). Based on the mass W of the adhesive layer at room temperature_r[g]And the mass W of the adhesive layer after heating to 200 deg.C₂₀₀[g]The thermal decomposition mass reduction rate R was calculated from the following formula (5).

R＝{(W_r－W₂₀₀)/W_r}×100[％] (5)

[ front Panel (Window film) ]

A polyimide film (thickness: 50 μm) having a hard coat layer (thickness: 10 μm) on one surface was prepared as a front panel.

[ polarizer layer ]

1. The following materials were prepared.

1) TAC film with thickness of 25 μm.

2) An alignment film-forming composition.

< Polymer 1 >

A polymer 1 having a photoreactive group, which is composed of the following structural units, was prepared.

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

3) Composition for forming polarizer layer

< polymerizable liquid Crystal Compound >

As the polymerizable liquid crystal compound, a polymerizable liquid crystal compound represented by the formula (1-1) [ hereinafter also referred to as Compound (1-1) ] and a polymerizable liquid crystal compound represented by the formula (1-2) [ hereinafter also referred to as Compound (1-2) ] were used.

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

< dichroic dye >

As the dichroic dye, azo dyes described in examples of Japanese patent application laid-open No. 2013-101328 represented by the following formulae (2-1a), (2-1b), and (2-3a) are used.

The composition for forming a polarizer layer [ hereinafter also referred to as composition (a-1) ] was prepared by: 75 parts by mass of the compound (1-1), 25 parts by mass of the compound (1-2), 2.5 parts by mass of each of the azo dyes represented by the above formulae (2-1a), (2-1b) and (2-3a) as dichroic dyes, 6 parts by mass of 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one (Irgacure369, manufactured by BASF Japan) as a polymerization initiator and 1.2 parts by mass of a polyacrylate compound (BYK-361N, manufactured by BYK-Chemie) as a leveling agent were mixed with 400 parts by mass of toluene as a solvent, and the resulting mixture was stirred at 80 ℃ for 1 hour.

4) Composition for forming protective layer (OC layer)

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

2. Manufacturing method

1) The alignment film-forming composition was applied to the TAC film side in the following manner.

First, a corona treatment is applied to the TAC film side. The conditions of the corona treatment were an output of 0.3kW and a treatment speed of 3 m/min. Thereafter, the composition (D-1) obtained as described above was coated on the TAC by a bar coating method, and heat-dried in a drying oven at 80 ℃ for 1 minute. The obtained dried film was subjected to polarized UV irradiation treatment to form a1 st alignment film (AL 1). The polarized light UV treatment was carried out by passing light irradiated from a UV irradiation device (SPOT CURE SP-7; manufactured by Usio Motor Co., Ltd.) through a wire grid (UIS-27132# #, manufactured by Ushi Motor Co., Ltd.) and measuring the cumulative light quantity at a wavelength of 365nm at 100mJ/cm²Under the conditions of (1). The thickness of the 1 st alignment film (AL1) was 100 nm.

2) The composition for forming a polarizer layer was applied to the side of the alignment film in the following manner.

First, the composition (a-1) was coated on the formed 1 st alignment film (AL1) by a bar coating method, dried by heating in a drying oven at 120 ℃ for 1 minute, and then cooled to room temperature. Using the UV irradiation apparatus described above, the cumulative light amount was 1200mJ/cm²The dried film was irradiated with ultraviolet light (365nm basis) to form a polarizer layer (pol). The thickness of the obtained polarizer layer (pol) was measured by a laser microscope (OLS 3000, manufactured by Olympus corporation), and it was 1.8. mu.m. A laminate composed of "TAC/AL 1/pol" was obtained in this manner.

3) The composition for forming a protective layer (OC layer) was applied to the polarizer layer side in the following manner.

The composition (E-1) was coated on the formed polarizer layer (pol) by a bar coating method so that the thickness after drying became 1.0 μm, and dried at a temperature of 80 ℃ for 3 minutes. In this manner, a laminate composed of "TAC film/cPL (AL1+ pol + protective layer)" was obtained.

[ phase difference layer ]

1. Material preparation

The following materials were prepared.

1) PET film with a thickness of 100 μm.

2) An alignment film-forming composition.

[ Polymer 1]

A polymer 1 having a photoreactive group, which is composed of the following structural units, was prepared.

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

3) Composition for forming phase difference layer

The ingredients shown below were mixed, and the resulting mixture was stirred at 80 ℃ for 1 hour, thereby obtaining composition (B-1).

A compound b-1 represented by the following formula: 80 parts by mass

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

Polymerization initiator (Irgacure369, 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one manufactured by BASF Japan): 6 parts by mass

Leveling agent (BYK-361N, polyacrylate compound, BYK-Chemie Co., Ltd.): 0.1 part by mass

Solvent (cyclopentanone): 400 parts by mass

2. Manufacturing method

1) The composition for forming an alignment film was applied to a PET film in the following manner.

A polyethylene terephthalate film (PET) having a thickness of 100 μm was prepared as a substrate, and the composition (D-1) was applied to the film by a bar coating method and heat-dried in a drying oven at 80 ℃ for 1 minute. The obtained dried film was subjected to polarized UV irradiation treatment to form a2 nd alignment film (AL 2). Polarized light UV treatment Using the UV irradiation device, the cumulative quantity of light measured at a wavelength of 365nm was 100mJ/cm²Under the conditions of (1). The polarization direction of the polarized light UV is set to 45 ° with respect to the absorption axis of the polarizer layer. In this manner, a laminate composed of "substrate (PET)/2 nd alignment film (AL 2)" was obtained.

2) The retardation layer-forming composition was applied to the orientation film side of the PET film in the following manner.

The composition (B-1) was coated on the 2 nd alignment film (AL2) of the 1 st substrate thus obtained by a bar coating method, dried by heating in a drying oven at 120 ℃ for 1 minute, and then cooled to room temperature. The obtained dried film was irradiated with a cumulative light amount of 1000mJ/cm using the UV irradiation device²Ultraviolet rays (365nm basis), thereby forming a retardation layer. The thickness of the obtained retardation layer was measured by a laser microscope (OLS 3000, manufactured by Olympus Co., Ltd.) to be 2.0. mu.m. The phase difference layer is a lambda/4 plate (QWP) exhibiting a phase difference value of lambda/4 in the in-plane direction. A laminate composed of "substrate (PET)/AL 2/QWP" was obtained in this manner.

[ common adhesive sheet ]

1) Polymerization of acrylic resins

The following components were reacted at 55 ℃ under nitrogen atmosphere with stirring, thereby obtaining an acrylic resin.

Butyl acrylate: 70 parts by mass

Methyl acrylate: 20 parts by mass

Acrylic acid: 2.0 parts by mass

Radical polymerization initiator (2, 2' -azobisisobutyronitrile): 0.2 part by mass

2) Liquid preparation of adhesive composition

The following ingredients were mixed to obtain an adhesive composition.

Acrylic resin: 100 parts by mass

Crosslinking agent ("Coronate L" manufactured by tokyo corporation): 1.0 part by mass

Silane coupling agent (trade name silicon corporation "X-12-981"): 0.5 part by mass

Ethyl acetate was added so that the total solid content concentration became 10 mass%, to obtain a pressure-sensitive adhesive composition.

3) Production of adhesive sheet

The obtained pressure-sensitive adhesive composition was applied by an applicator to a release-treated surface of a polyethylene terephthalate film (heavy separator, thickness 38 μm) which had been subjected to release treatment so that the thickness after drying became 5 μm. The coating layer was dried at 100 ℃ for 1 minute to obtain a film having an adhesive layer. Thereafter, another polyethylene terephthalate film (light separator, 38 μm thick) subjected to mold release treatment was attached to the exposed surface of the adhesive layer. Thereafter, the mixture was aged at 23 ℃ and 50% RH relative humidity for 7 days to obtain a light separator/a common adhesive layer/a heavy separator.

[ example 1]

The laminate was produced according to the steps shown in (a) to (e) of fig. 4. First, a laminate 410[ TAC film 301/cPL ((AL1+ pol)302/OC layer 303) ] including the above-described polarizer layer and the above-described common adhesive sheet 420 (light spacer 304/common adhesive layer 305/heavy spacer 306) were prepared ((a) of fig. 4). Laminate a430 was obtained by applying corona treatment (output 0.3KW, speed 3 m/min) to the OC layer 303 side of laminate 410 including the polarizer layer and the surface of common adhesive sheet 420 from which light separator 304 was peeled, and then laminating them. The retardation layer 440[ base material (PET)308/AL2/QWP 307] (FIG. 4 (b)) was prepared.

Next, the QWP 307 side of the retardation layer 440 and the surface of the laminate a430 from which the heavy separator 306 was peeled were subjected to corona treatment (output 0.3KW, speed 3 m/min), and then laminated to obtain a laminate b 450. Thereafter, the adhesive sheet a11 produced as described above was prepared as an adhesive sheet 460 (light separator 309/adhesive layer 310/heavy separator 311) (fig. 4 (c)). The adhesive layer 310 of the adhesive sheet 460 corresponds to the 2 nd adhesive layer.

Laminate c470 was obtained by laminating the surface of laminate b450 from which substrate (PET)308 was peeled and the surface of adhesive sheet 460 from which light separator 309 was peeled after corona treatment (output 0.3KW, speed 3 m/min). Further, the psa sheet a12 produced as described above was prepared as a psa sheet 490 (light separator 314/psa layer 315/heavy separator 316), and the surface from which the light separator 314 was peeled and the polyimide film 313 side of the front panel 480 (polyimide film 313/hard coat layer 312) were subjected to corona treatment (output 0.3KW, speed 3 m/min) and then laminated to obtain a laminate d500 (fig. 4 (d)). The adhesive layer 315 of the adhesive sheet 490 corresponds to the 1 st adhesive layer.

The surface of the laminate d500 from which the heavy separator 316 was peeled and the TAC film 301 side of the laminate c470 were subjected to corona treatment (output 0.3KW, speed 3 m/min) and then bonded to each other, thereby obtaining a laminate 300 of example 1 (fig. 4 (e)). The laminate of example 1 was evaluated for room temperature bendability and room temperature adhesion durability by the methods described below. The results are shown in Table 4.

Examples 2 to 6, comparative examples 1 and 2

Laminates of examples 2 to 6 and comparative examples 1 and 2 were produced in the same manner as in example 1 except that adhesive sheets having adhesive layers shown in table 4 were used in example 1 instead of using the adhesive sheets a11 and a 12. The laminates of examples 2 to 6 and comparative examples 1 and 2 were evaluated for room temperature bendability and room temperature adhesion durability by the methods described later. The results are shown in table 4.

< Normal temperature bendability >

The laminates obtained in the examples and comparative examples were subjected to an evaluation test for confirming room temperature bendability using a bending apparatus (STS-VRT-500, manufactured by Science Town). The heavy separator 311 was peeled off and bonded to a 100 μm thick PET film to obtain a laminate. The PET film corresponds to the back panel. Fig. 3 is a diagram schematically showing the method of the evaluation test. As shown in fig. 3, two independently movable tables 501 and 502 are disposed so that the gap C is 6.0mm (3R), the center in the width direction is located at the center of the gap C, and the hard coat layer 312 is located below, and the laminate is fixed and disposed in this manner ((a) of fig. 3). Then, the two tables 501 and 502 are rotated upward by 90 degrees around the position P1 and the position P2 as the center of the rotation axis, and a bending force (a bending force for making the front panel 480 outward) is applied to a region of the laminated body corresponding to the gap C of the tables ((b) of fig. 3). Thereafter, the two tables 501 and 502 are returned to their original positions (fig. 3 (a)). The above series of operations was completed, and the number of times of application of the bending force was counted as 1 time. After repeating this at a temperature of 25 ℃, it was confirmed whether or not air bubbles were generated in the pressure-sensitive adhesive layer in the region of the laminate corresponding to the gap C of the mounting tables 501 and 502. The moving speed of the mounting tables 501 and 502 and the step of applying the bending force are the same in the evaluation test of any laminate. "adhesive release" means that the adhesive layer bleeds out from the end of the laminate.

A: no bubble was generated even if the number of bending force applications reached 10 ten thousand.

B: bubbles are generated when the number of times of applying the bending force is 5 ten thousand or more and less than 10 ten thousand.

C: bubbles are generated when the number of times of applying the bending force is 2 ten thousand or more and less than 5 ten thousand.

D: bubbles are generated when the number of times of application of the bending force is 1 ten thousand or more and less than 2 ten thousand.

E: the number of bending force applications is less than 1 ten thousand resulting in bubble/adhesive detachment.

Durability of high temperature adhesion

The laminates obtained in each example and each comparative example were cut into a width of 100mm × a length of 100 mm. The heavy separator 311 is peeled off and attached to the alkali-free glass. The pressure-bonding treatment was carried out in an autoclave (50 ℃ C., 5 atm) for about 20 minutes, and the autoclave was maintained under constant temperature and humidity conditions (23 ℃ C., 50% RH) for 4 hours. The sample was put in an oven at 85 ℃ and judged for the presence of floating, peeling, and bubbling after 250 hours. In the laminated laminate, the alkali-free glass corresponds to the back plate.

O: the appearance change such as floating, peeling, foaming and the like was hardly observed.

And (delta): the appearance change such as floating, peeling, foaming and the like is slightly conspicuous.

X: the appearance changes such as floating, peeling, foaming and the like are obviously seen.

[ Table 4]

Examples 1 to 6 satisfy the relationship "R1. ltoreq.R 2", and R1 and R2 are each contained in the range of 10 to 20% by mass.

Description of the symbols

100. 200 laminated body, 101 front panel, 102 1 st adhesive layer, 103 polarizer layer, 104 nd 2 nd adhesive layer, 105 back panel, 106 st phase difference layer, 107 nd 2 nd phase difference layer, 108, 109 adhesive layer, 301TAC film, 302pol, 303OC layer, 305 common adhesive layer, 306, 311, 316 heavy separator, 307QWP, 308 base material, 304, 309, 314 light separator, 310, 315 adhesive layer, 312 hard coat layer, 313 polyimide film, 410 laminated body containing polarizer layer, 420 common adhesive sheet, 430 laminated body a, 440 phase difference layer, 450 laminated body b, 460, 490 adhesive sheet, 470 laminated body c, 500 laminated body d, 501, 502 carrying platform.