阅读说明：本技术 光学层叠体和显示装置 (Optical laminate and display device ) 是由 姜大山 李昇祐 金东辉 于 2019-09-26 设计创作，主要内容包括：本发明提供一种光学层叠体,是介由粘合剂层层叠有前面板和背面板,且在前面板或背面板的粘合剂层侧的表面上部分地形成有着色层的能够弯曲的光学层叠体,可抑制在层间混入具有10μm以上的大小的气泡。一种光学层叠体,依次层叠有前面板、包含第1粘合剂层和第2粘合剂层的粘合层以及背面板,且具有在前面板或背面板的任一者的粘合剂层侧部分地形成的着色层,粘合剂层以第2粘合剂层为着色层侧的方式配置,以在俯视光学层叠体时至少覆盖着色层内侧的端部的方式层叠,第1粘合层和第2粘合层包含(甲基)丙烯酸系树脂,所述光学层叠体满足(1)0.01MPa≤第1粘合层和第2粘合剂层的储存弹性模量≤0.1MPa和(2)0.5≤第2粘合层的损耗角正切≤0.8。(The invention provides an optical laminate, which is a bendable optical laminate, wherein a front panel and a back panel are laminated through an adhesive layer, and a coloring layer is partially formed on the surface of the front panel or the back panel on the adhesive layer side, and bubbles with the size of more than 10 mu m can be inhibited from mixing in the interlayer. An optical laminate comprising a front plate, an adhesive layer comprising a1 st adhesive layer and a2 nd adhesive layer, and a back plate, which are laminated in this order, and further comprising a colored layer partially formed on the adhesive layer side of either the front plate or the back plate, wherein the adhesive layer is disposed such that the 2 nd adhesive layer is on the colored layer side, and is laminated so as to cover at least the end portion inside the colored layer when the optical laminate is viewed in plan, wherein the 1 st adhesive layer and the 2 nd adhesive layer comprise a (meth) acrylic resin, and the optical laminate satisfies (1) a storage elastic modulus of 0.01MPa or less of the 1 st adhesive layer and the 2 nd adhesive layer of 0.1MPa or less, and (2) a loss tangent of 0.5 or less of the 2 nd adhesive layer of 0.8 or less.)

1. An optical laminate comprising a front plate, an adhesive layer, and a back plate laminated in this order, the optical laminate having a colored layer partially formed on either the adhesive layer side of the front plate or the adhesive layer side of the back plate,

the pressure-sensitive adhesive layer comprises a1 st pressure-sensitive adhesive layer and a2 nd pressure-sensitive adhesive layer, and is laminated such that the 2 nd pressure-sensitive adhesive layer is on the colored layer side,

the adhesive layer is disposed so as to cover at least an end portion of the inner side of the color layer in a plan view of the optical laminate,

the 1 st adhesive layer and the 2 nd adhesive layer contain a (meth) acrylic resin,

the optical laminate satisfies the following (1) and (2):

(1) the storage elastic modulus of the 1 st adhesive layer and the 2 nd adhesive layer is not less than 0.01MPa and not more than 0.1MPa,

(2) the loss tangent of the 2 nd adhesive layer is more than or equal to 0.5 and less than or equal to 0.8.

2. The optical stack of claim 1, wherein the loss tangent of the 1 st adhesive layer is different from the loss tangent of the 2 nd adhesive layer.

3. The optical stack of claim 1 or 2, wherein the thickness of the 2 nd adhesive layer is greater than the thickness of the colored layer.

4. The optical laminate of any one of claims 1-3, wherein the combined thickness of the 1 st adhesive layer and the 2 nd adhesive layer is from 25 μm to 150 μm.

5. A display device comprising the optical stack of any of claims 1-4.

6. The optical laminate of any one of claims 1-4, wherein the 1 st adhesive layer has a compressive modulus of elasticity of 3MPa to 12 MPa.

7. The optical laminate of any one of claims 1-4 and 6, wherein the 2 nd adhesive layer has a compressive modulus of elasticity of 3MPa to 5 MPa.

Technical Field

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

Background

Patent document 1 describes a foldable display device in which a display panel, a polarizing member provided on the display panel, and a window provided on the polarizing member are bonded with adhesive members, respectively.

Patent document 2 describes a double-sided adhesive sheet having a1 st adhesive layer and a2 nd adhesive layer for bonding a display device and an optical member. Patent document 3 describes an adhesive sheet having a1 st adhesive layer and a2 nd adhesive layer disposed between a protective panel and a polarizing film.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-126061

Patent document 2: japanese patent laid-open publication No. 2016-194085

Patent document 3: japanese patent No. 4806730

Disclosure of Invention

In a bendable optical laminate in which a front plate and a back plate are laminated via an adhesive layer and a colored layer is partially formed on the adhesive layer side of the front plate or the back plate, air bubbles having a size of 10 μm or more may be mixed between the layers.

The invention aims to provide a bendable optical laminate in which a front plate and a back plate are laminated via an adhesive layer, and a colored layer is partially formed on the adhesive layer side of the front plate or the back plate, wherein bubbles having a size of 10 [ mu ] m or more are prevented from being mixed between the layers.

The present invention provides a laminate and a display device shown below.

[1] An optical laminate comprising a front plate, an adhesive layer, and a back plate laminated in this order, the optical laminate having a colored layer partially formed on either the adhesive layer side of the front plate or the adhesive layer side of the back plate,

the pressure-sensitive adhesive layer comprises a1 st pressure-sensitive adhesive layer and a2 nd pressure-sensitive adhesive layer, and is laminated such that the 2 nd pressure-sensitive adhesive layer is on the colored layer side,

the adhesive layer is disposed so as to cover at least an end portion of the inner side of the color layer in a plan view of the optical laminate,

the 1 st adhesive layer and the 2 nd adhesive layer contain a (meth) acrylic resin,

the optical laminate satisfies the following (1) and (2).

(1) The storage elastic modulus of the 1 st adhesive layer and the 2 nd adhesive layer is not more than 0.01MPa and not more than 0.1MPa

(2) The loss tangent of the 2 nd adhesive layer is more than or equal to 0.5 and less than or equal to 0.8

[2] The optical laminate according to [1], wherein the loss tangent of the 1 st adhesive layer is different from the loss tangent of the 2 nd adhesive layer.

[3] The optical laminate according to [1] or [2], wherein the thickness of the 2 nd pressure-sensitive adhesive layer is larger than the thickness of the colored layer.

[4] The optical laminate according to any one of [1] to [3], wherein the total thickness of the 1 st pressure-sensitive adhesive layer and the 2 nd pressure-sensitive adhesive layer is 25 μm to 150 μm.

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

[6] The optical laminate according to any one of [1] to [4], wherein the 1 st pressure-sensitive adhesive layer has a compressive modulus of elasticity of 3MPa to 12 MPa.

[7] The optical laminate according to any one of [1] to [4], wherein the 2 nd pressure-sensitive adhesive layer has a compressive modulus of elasticity of 3MPa to 5 MPa.

According to the present invention, there can be provided a bendable optical laminate in which a front plate and a back plate are laminated via an adhesive layer, and a colored layer is partially formed on the adhesive layer side of the front plate or the back plate, wherein bubbles having a size of 10 μm or more are prevented from being mixed between the layers.

Drawings

Fig. 1 is a schematic cross-sectional view showing an optical laminate according to an embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view of a laminate schematically illustrating a method for producing a laminate according to the present invention.

Fig. 3 is a schematic cross-sectional view of a laminate schematically illustrating a method for producing a laminate according to the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments below. In all the drawings below, the scale of each constituent element shown in the drawings is appropriately adjusted to show the constituent element for easy understanding, and the scale of each constituent element does not necessarily coincide with the scale of an actual constituent element.

< optical laminate >

Fig. 1 is a schematic cross-sectional view of an optical stack according to an embodiment of the present invention. An optical laminate (hereinafter, also simply referred to as "laminate") 100 shown in fig. 1 is formed by laminating a front plate 10, an adhesive layer 20, and a back plate 30 in this order. Laminate 100 further includes colored layer 40 partially formed on the side of back surface plate 30 adjacent to adhesive layer 20. The pressure-sensitive adhesive layer 20 includes a1 st pressure-sensitive adhesive layer 21 and a2 nd pressure-sensitive adhesive layer 22, and is laminated such that the 2 nd pressure-sensitive adhesive layer 22 is on the colored layer side.

The colored layer 40 may be formed partially on the adhesive layer 20 side of the front panel 10 instead of partially on the adhesive layer 20 side of the back panel 30.

The laminate 100 can be bent. Bendable means that bending with a radius of curvature of 3mm is possible. The laminate 100 preferably does not crack even if the number of times of bending is 1 ten thousand with a radius of curvature of 3mm on the inner surface of the laminate 100.

The thickness of the laminate 100 is not particularly limited, and is, for example, 50 to 1000 μm, and more preferably 100 to 500 μm, since it varies depending on the functions required for the laminate, the application 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 rectangular, the length of the long side may be, for example, 10mm to 1400mm, preferably 50mm to 600 mm. The length of the short side may be, for example, 5mm to 800mm, preferably 30mm to 500mm, and more preferably 50mm to 300 mm.

When the laminate 100 has a rectangular shape in plan view, the front panel 10 and the back panel 30 may have the same length on each side, and the front panel 10 and the back panel 30 preferably have the same position on the end. When the laminate 100 has a square shape in plan view, the position of the end of the adhesive layer 20 may be the same as the position of the end of the front panel 10 or the back panel 30, or may be inside.

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. The laminate 100 is suitable for a flexible display device.

Conventionally, an optical laminate having flexibility in which a colored layer is partially formed on a surface of a front plate or a back plate on the side of a pressure-sensitive adhesive layer has the following problems: bubbles (hereinafter, also referred to as specific bubbles) having a length of 10 μm or more are generated between the colored layer and the adhesive layer, between the 1 st adhesive layer and the 2 nd adhesive layer, and between the front or rear panel and the adhesive layer. The present inventors have intensively studied for suppressing air bubbles, and as a result, they have found that a level difference is generated in the thickness direction of the laminate between a region where the colored layer is present and a region where the colored layer is not present, the adhesive layer formed on the level difference cannot follow the level difference, and air bubbles are likely to be generated between the adhesive layer and the front panel or the rear panel where the colored layer is formed, particularly, at the level difference portion between the front panel or the rear panel and the colored layer. Accordingly, as a result of further studies focusing on the pressure-sensitive adhesive layer, it was found that by making the pressure-sensitive adhesive layer have a 2-layer structure, the loss tangent (hereinafter also referred to as tan δ) of the layer in contact with the colored layer out of the 2 layers is within a specific range, each pressure-sensitive adhesive layer contains an acrylic resin and exhibits a specific storage elastic modulus, and bubbles can be suppressed without impairing the bendability.

The specific bubbles can be observed by observing a transmission image of the laminate with an optical microscope. The specific air bubbles are generated in parallel at the end portions of the laminated body inside the colored layers in the planar direction. Therefore, the shape of the specific bubble is mostly linear. When the specific bubble is linear, the length is 10 μm or more, and the width may be, for example, 0.01 to 5 μm. When the specific air bubbles are generated, they are often generated both between the colored layer and the adhesive layer and between the front plate or the back plate and the adhesive layer, and in this case, they are often generated at positions of an axis symmetrical to an end portion inside the colored layer with reference to the reference.

(front panel)

The front panel 10 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 resin plate-like body (e.g., a resin plate, a resin sheet, a resin film, etc.), and a glass plate-like body (e.g., a glass plate, a glass film, etc.). The front panel may be a layer constituting the outermost surface of the display device.

The thickness of the front panel 10 may be, for example, 30 to 2000 μm, preferably 50 to 1,000 μm, and more preferably 50 to 500 μm. 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 10 is a resin plate-like body, the resin plate-like body is not limited as long as it can transmit light. Examples of the resin include films made of polymers such as triacetyl cellulose, acetyl cellulose 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. The thickness of the resin plate-like body is, for example, 30 to 2000. mu.m, preferably 50 to 1000. mu.m, more preferably 50 to 500 μm, and may be 100 μm or less.

The front panel 10 may be a film having a hard coat layer provided on at least one side of a substrate film to further increase the hardness. 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, polyurethane resins, amide resins, and epoxy resins. The hard coating may also contain additives for strength enhancement. The additive is not limited, and examples thereof include inorganic fine particles, organic fine particles, and a mixture thereof.

When the front panel 10 is a glass plate, a strengthened glass for display is preferably used as the glass plate. The thickness of the glass plate is, for example, 10 to 1000. mu.m.

By using the glass plate, the front panel 10 having excellent mechanical strength and surface hardness can be constituted.

When the laminate 100 is used for a display device, the front panel 10 may function as a window film in the display device. The front panel 10 may have a function as a touch sensor, a blue light cut-off function, a viewing angle adjustment function, and the like.

(adhesive layer)

The adhesive layer 20 may be a layer interposed between the front panel 10 and the back panel 30 and bonded to each other.

The adhesive layer 20 includes a1 st adhesive layer 21 and a2 nd adhesive layer 22. The composition of the adhesive of the 1 st adhesive layer 21 and the 2 nd adhesive layer 22 may be different from each other. The pressure-sensitive adhesive layer 20 may be a laminate obtained by laminating, for example, a1 st pressure-sensitive adhesive layer 21 and a2 nd pressure-sensitive adhesive layer 22, or may be a laminate obtained by laminating a1 st pressure-sensitive adhesive layer 21 and a2 nd pressure-sensitive adhesive layer 22 in contact with each other. The adhesive layer 20 is laminated on the front plate 10 or the back plate 30 so that the 2 nd adhesive layer 22 is on the colored layer 40 side. The pressure-sensitive adhesive layer 20 may be laminated such that the 2 nd pressure-sensitive adhesive layer 22 is closer to the colored layer 40 than the 1 st pressure-sensitive adhesive layer 21, or may be laminated so as to be in contact with the colored layer 40. The adhesive layer 20 is laminated so as to cover at least an end portion inside the color layer 40 in a plan view of the optical laminate 100. The level difference of the colored layer 40 is absorbed by the adhesive layer 20 including the 1 st adhesive 21 having a specific storage elastic modulus and the 2 nd adhesive layer 22 having a specific elastic modulus and a loss tangent, and the adhesive layer plane becomes smooth, and there is a tendency that the mixing of specific air bubbles is easily suppressed. From the viewpoint of absorbing the level difference, the adhesive layer 20 is preferably laminated so as to cover the entire colored layer 40 and the entire portion of the front plate 10 or the back plate 30 where the colored portion is not formed when the optical laminate 100 is viewed in plan. In the present specification, a planar view means a view from the thickness direction of the layer.

(1 st adhesive layer)

The 1 st adhesive layer 21 may be attached to the side of the front plate 10 or the back plate 30 on which the colored layer 40 is not formed. The 1 st adhesive layer 21 contains a (meth) acrylic resin.

The 1 st adhesive layer 21 has a storage modulus of elasticity of 0.01 to 0.1MPa, preferably 0.02 to 0.08 MPa. When the storage elastic modulus of the 1 st pressure-sensitive adhesive layer 21 is 0.01MPa to 0.1MPa, the laminate 100 tends to easily obtain excellent bendability. In the present invention, the storage modulus of elasticity can be measured by the measurement method described in the following section of examples. The storage modulus of elasticity may take a value at ordinary temperature (temperature 23 ℃ C.).

The storage elastic modulus of the 1 st adhesive layer 21 can be adjusted by selection of a material for forming the 1 st adhesive layer 21, the thickness of the 1 st adhesive layer 21, production conditions of the 1 st adhesive layer 21, for example, an amount of UV irradiation when the 1 st adhesive layer 21 is composed of an active energy ray-curable adhesive composition, and the like, and combinations thereof. For example, if a monomer having a relatively large molecular weight is used for producing a (meth) acrylic resin contained in the pressure-sensitive adhesive composition 1 described later, the storage elastic modulus of the 1 st pressure-sensitive adhesive layer 21 tends to increase. In addition, for example, if the UV irradiation amount is increased, the storage elastic modulus of the 1 st adhesive layer 21 tends to increase.

The loss tangent of the 1 st adhesive layer 21 is, for example, 0.7 or less, preferably less than 0.5, and more preferably 0.3 or less.

The 1 st pressure-sensitive adhesive layer 21 may be formed of a pressure-sensitive adhesive composition containing a (meth) acrylic resin as a main component (hereinafter also referred to as a pressure-sensitive adhesive composition 1). In the present specification, "(meth) acrylic resin" means at least 1 selected from acrylic resins and methacrylic resins. The same applies to other terms with "(methyl)". The adhesive composition 1 may be an active energy ray-curable type or a thermosetting type.

As the (meth) acrylic resin (base polymer) used in the adhesive composition 1, for example, a polymer or copolymer in which 1 or 2 or more kinds of monomers are used among (meth) acrylic esters such as butyl (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 can be preferably used. The base polymer preferably copolymerizes polar monomers. Examples of the polar monomer include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, and the like, such as (meth) acrylic acid, 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, acrylamide, N-dimethylaminoethyl (meth) acrylate, and glycidyl (meth) acrylate.

The adhesive composition 1 may comprise only the above-mentioned base polymer, but usually also contains a crosslinking agent. Examples of the crosslinking agent include metal ions having a valence of 2 or more and a metal carboxylate salt formed between the crosslinking agent and a carboxyl group; a polyamine compound and a substance forming an amide bond with a carboxyl group; polyepoxy compounds, polyhydric alcohols, and substances forming ester bonds with carboxyl groups; a polyisocyanate compound and a substance forming an amide bond with a carboxyl group. Among them, polyisocyanate compounds are preferable.

The active energy ray-curable pressure-sensitive adhesive composition is a pressure-sensitive adhesive composition having a property of being cured by irradiation with an active energy ray such as an ultraviolet ray or an electron beam, and having a property of having adhesiveness even before irradiation with an active energy ray, and being capable of being bonded to an adherend such as a film and being cured by irradiation with an active energy ray to adjust the bonding force. The active energy ray-curable adhesive composition is preferably an ultraviolet-curable adhesive composition. The active energy ray-curable adhesive composition further contains an active energy ray-polymerizable compound in addition to the base polymer and the crosslinking agent. Further, a photopolymerization initiator, a photosensitizer and the like may be contained as needed.

The adhesive composition 1 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, antifoaming agents, anticorrosion agents, and photopolymerization initiators, which impart light scattering properties.

The adhesive composition can be formed by applying the organic solvent diluted solution of the adhesive composition 1 to a substrate and drying the applied solution. When an active energy ray-curable pressure-sensitive adhesive composition is used, a cured product having a desired degree of curing can be obtained by irradiating the pressure-sensitive adhesive layer formed with an active energy ray.

From the viewpoint of the following properties and the flexibility, the thinner the thickness of the 1 st pressure-sensitive adhesive layer 21 is, the more preferable is, for example, 3 μm to 100 μm, more preferably 5 μm to 50 μm, and may be 20 μm or more.

(No. 2 adhesive layer)

The 2 nd adhesive layer 22 may be attached to the side of the front surface plate 10 or the rear surface plate 30 on which the colored layer 40 is formed. The 2 nd adhesive layer 22 contains a (meth) acrylic resin.

The 2 nd adhesive layer 22 has a loss tangent of 0.5 to 0.8, preferably 0.55 to 0.75. When the loss tangent of the 2 nd pressure-sensitive adhesive layer 22 is 0.5 to 0.8, excellent conformability tends to be easily obtained. In the present invention, the loss tangent can be measured by the measurement method described in the column of the example described later. The loss tangent can be a value at ordinary temperature (temperature 23 ℃ C.).

The loss tangent of the 2 nd adhesive layer 22 may be adjusted by a combination of the selection of the material forming the 2 nd adhesive layer 22, the thickness of the 2 nd adhesive layer 22, the manufacturing conditions of the 2 nd adhesive layer 22, and the like.

For example, if a monomer having a relatively large molecular weight is used for producing a (meth) acrylic resin contained in the pressure-sensitive adhesive composition 2 described later, the loss tangent of the 2 nd pressure-sensitive adhesive layer 22 tends to increase.

The storage modulus of elasticity of the 2 nd adhesive layer 22 is 0.01MPa to 0.1MPa, preferably 0.02MPa to 0.08 MPa. When the storage elastic modulus of the 2 nd pressure-sensitive adhesive layer 22 is 0.01MPa to 0.1MPa, the laminate 100 tends to easily obtain excellent bendability.

The method of adjusting the storage elastic modulus of the 2 nd adhesive layer 22 is the same as the method exemplified in the description of the 1 st adhesive layer 21. The 2 nd adhesive layer 22 may be formed of an adhesive composition (hereinafter also referred to as adhesive composition 2). The pressure-sensitive adhesive composition 2 may be formed of a pressure-sensitive adhesive composition containing the above (meth) acrylic resin as a main component. From the viewpoint of loss tangent, the adhesive composition 2 is preferably an active energy ray-curable type.

The (meth) acrylic resin (base polymer), crosslinking agent, photopolymerization initiator, additive, and the like contained in the adhesive composition 2 are the same as those exemplified in the description of the adhesive composition 1. The 2 nd adhesive layer may be formed in the same manner as the 1 st adhesive layer.

From the viewpoint of absorbing the level difference of the colored layer 40, the thickness of the 2 nd pressure-sensitive adhesive layer 22 is preferably larger than the thickness of the colored layer 40, and is, for example, preferably 3 to 100 μm, more preferably 5 to 50 μm, and may be 20 μm or more.

(Total thickness of adhesive layer)

The total thickness of the 1 st pressure-sensitive adhesive layer 21 and the 2 nd pressure-sensitive adhesive layer 22 may be, for example, 25 to 150. mu.m, preferably 30 to 125. mu.m, and more preferably 40 to 100. mu.m. When the total thickness is within the above range, good step following property and bending resistance tend to be easily obtained.

(difference in loss tangent)

The loss tangent of the 1 st adhesive layer 21 may be different from the loss tangent of the 2 nd adhesive layer 22, for example, and is preferably smaller than the loss tangent of the 2 nd adhesive layer 22. When the loss tangent of the 1 st adhesive layer 21 is different from that of the 2 nd adhesive layer 22, the absolute value of the difference may be, for example, 0.05 or more, and preferably 0.25 to 0.5.

(modulus of elasticity under compression)

The 1 st adhesive layer may have a compressive modulus of elasticity of, for example, 3MPa to 12 MPa. When the compression elastic modulus of the 1 st pressure-sensitive adhesive layer is 3MPa or more, the 1 st pressure-sensitive adhesive layer tends to be difficult to peel from an adherend during bending. On the other hand, when the compressive elastic modulus of the 1 st adhesive layer is 12MPa or less, cracks tend to be less likely to occur in the front plate and the rear plate during bending. From the viewpoint of suppressing the above-mentioned peeling and cracking, the compressive elastic modulus of the 1 st pressure-sensitive adhesive layer is preferably 3MPa to 10 MPa.

The compression modulus of elasticity of the 2 nd adhesive layer may be, for example, 3MPa to 5 MPa. When the compression elastic modulus of the 2 nd pressure-sensitive adhesive layer is within the above range, the 2 nd pressure-sensitive adhesive layer tends to have excellent step following properties.

(Back plate)

As the back plate 30, a plate-like body capable of transmitting light, a component used in a general display device, or the like can be used.

The thickness of back plate 30 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 back surface plate 30 may be composed of only 1 layer or 2 or more layers, and the plate-like body exemplified for the plate-like body described above for back surface plate 10 may be used.

Examples of the constituent elements used in a typical display device used for the back panel 30 include a polarizing plate, a touch sensor panel, and a retardation film.

(polarizing plate)

Examples of the polarizing plate include a stretched film having a dye having absorption anisotropy adsorbed thereon, a film obtained by coating and curing a dye having absorption anisotropy, and the like as a polarizer. Examples of the dye having absorption anisotropy include dichroic dyes. 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 disazo compound such as c.i. direct red 39, and a dichroic direct dye composed of a compound such as trisazo or tetrazo. Examples of the film coated with a dye having absorption anisotropy, which can be used as a polarizer, include a stretched film in which a dye having absorption anisotropy is adsorbed, and a film having a layer obtained by coating a composition containing a dichroic dye having liquid crystallinity or a composition containing a dichroic dye and a polymerizable liquid crystal. A film obtained by applying and curing a dye having absorption anisotropy is preferable because it is not limited in the bending direction as compared with a stretched film having an absorbed dye having absorption anisotropy.

(1) Polarizing plate having stretched film as polarizer

A polarizing plate having a polarizer made of a stretched film having a dye having absorption anisotropy adsorbed thereon will be described. A stretched film as a polarizer, to which a dye having absorption anisotropy is adsorbed, can be usually produced through the following steps: a step of uniaxially stretching a polyvinyl alcohol resin film; a step of dyeing a polyvinyl alcohol resin film with a dichroic dye to adsorb 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 with water after the treatment with the aqueous boric acid solution. The polarizer may be used as it is, or a film obtained by laminating a transparent protective film on one or both surfaces thereof may be used as the polarizing plate. The thickness of the polarizer thus obtained is preferably 2 to 40 μm.

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 acrylamides having an ammonium group.

The saponification degree of the polyvinyl alcohol resin is usually 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 about 1000 to 10000, and preferably in the range of 1500 to 5000.

A film obtained by forming such a polyvinyl alcohol resin is used as a raw film of a polarizing plate. The method for forming the film of the polyvinyl alcohol resin is not particularly limited, and the film can be formed by a known method. The thickness of the polyvinyl alcohol-based raw film may be, for example, about 10 μm to 150 μm.

The uniaxial stretching of the polyvinyl alcohol resin film may be performed before, simultaneously with, or after dyeing with a dichroic dye. When the uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before the boric acid treatment or may be performed in the boric acid treatment. In addition, uniaxial stretching may be performed in these plural stages. In the case of uniaxial stretching, the uniaxial stretching may be performed between rolls having different peripheral speeds, or the uniaxial stretching may be performed using a hot roll. The uniaxial stretching may be dry stretching in which stretching is performed in the air, or wet stretching in which a polyvinyl alcohol resin film is stretched in a swollen state using a solvent. The draw ratio is usually about 3 to 8 times.

The thickness of the polarizing plate provided with a stretched film as a polarizer may be, for example, 1 μm to 400 μm, or 5 μm to 100 μm.

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

(2) Polarizing plate having polarizer made of film formed of liquid crystal layer

A polarizing plate including a film formed of a liquid crystal layer as a polarizer will be described. Examples of the film coated with a dye having absorption anisotropy to be used as a polarizer include a film obtained by coating a composition containing a dichroic dye having liquid crystallinity or a composition containing a dichroic dye and a polymerizable liquid crystal on a substrate and curing the composition. The film may be peeled from the substrate or used as a polarizing plate together with the substrate, or may be used as a polarizing plate having a protective film on one surface or both surfaces thereof. Examples of the protective film include those similar to polarizing plates provided with the stretched film as a polarizer.

The thinner the film obtained by applying and curing the dye having absorption anisotropy, the more preferable, but the too thin film tends to decrease the strength and deteriorate the processability. The thickness of the film is usually 20 μm or less, preferably 5 μm or less, and more preferably 0.5 to 3 μm.

Specific examples of the film obtained by applying the dye having absorption anisotropy include films described in japanese patent laid-open No. 2012-33249 and the like.

The thickness of the polarizing plate provided with a film formed of a liquid crystal layer as a polarizer may be, for example, 1 μm to 50 μm.

A retardation film (for example, a retardation film including a λ/4 plate as a retardation layer) described later may be laminated on the polarizing plate to obtain a circularly polarizing plate. At this time, the absorption axis of the polarizer may make an angle of 45 ° ± 10 ° with the slow axis of the λ/4 plate.

(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 sensing 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 is 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 the inner front surface of each substrate, and a touch position detection circuit. In an image display device provided with a resistive touch sensor, if the surface of the front panel 10 is touched, the opposing resistive films are short-circuited, and a current flows through the resistive films. The touch position detection circuit detects a change in voltage at that time, and detects a touched position.

An example of a capacitive coupling type touch sensor 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, if the surface of the front panel 10 is touched, the transparent electrode is grounded at the touched point via the capacitance of the human body. The touch position detection circuit detects the grounding of the transparent electrode and detects the touched position.

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

(retardation film)

The retardation film may include 1 or 2 or more retardation layers. The retardation layer may be a positive A plate or a positive C plate such as a λ/4 plate or a λ/2 plate. The retardation layer may be formed of a resin film exemplified as a material of the protective film, or may be formed of a layer obtained by curing a polymerizable liquid crystal compound. The retardation film may further include an alignment film and a substrate film.

The thickness of the retardation film may be, for example, 1 μm to 50 μm.

(colored layer)

When the colored layer 40 is used in a display device, for example, it has a function of improving visibility of a displayed image or the like and making it impossible to visually recognize wiring or the like in the display device from outside the display device. The colored layer 40 may have an optical density of 3 or more, preferably 5.0 or more, for example.

The shape and color of the colored layer 40 are not limited, and can be appropriately selected according to the application and design of a display device using the laminate, for example. The colored layer 40 contains a colorant. The colored layer 40 may be composed of only 1 layer, or may be composed of 2 or more layers. When the colored layer 40 is composed of 2 or more layers, at least 1 of the 2 or more layers is a colorant-containing layer containing a colorant, and the remaining layer may or may not contain a colorant. Examples of the color of the colorant include black, red, white, dark blue, silver, and gold. The colored layer 40 may have a colorant-containing layer having high light-shielding properties, a base layer for improving adhesion, or the like below the colorant-containing layer containing a colorant. Further, a transparent protective layer may be provided to cover the colorant-containing layer.

The colorant may be appropriately selected according to the desired color. Examples of the colorant include inorganic pigments such as carbon black such as titanium dioxide, zinc white and acetylene black, iron black, bengal red, chrome vermilion, ultramarine blue, cobalt blue, chrome yellow and titanium yellow; organic pigments or dyes such as phthalocyanine blue, indanthrone blue, isoindone yellow, benzidine yellow, quinacridone red, polyazo red, perylene red, aniline black, and the like; metallic pigments made of scaly foils of aluminum, brass, or the like; a pearl lustre pigment (pearl pigment) composed of a scaly foil of titanium dioxide-coated mica, basic lead carbonate or the like. In this specification, the metal contained in the plating layer is also contained in the colorant.

Each layer of the colored layer 40 can be formed by a printing method, a coating method, a plating method, or the like. Colored layer 40 may be partially formed on the surface of back panel 30 on the side of adhesive layer 20, and colored layer 40 may be partially formed on the surface of front panel 10 on the side of adhesive layer 20.

The colored layer 40 may be formed directly on the surface on the side of the adhesive layer 20 of the front plate 10 or on the surface on the side of the adhesive layer 20 of the rear plate 30, or may be formed by transferring a colored layer formed on another substrate onto the surface on the side of the adhesive layer 20 of the front plate 10 or on the surface on the side of the adhesive layer 20 of the rear plate 30. Specific examples of the printing method include gravure printing, offset printing, screen printing, and transfer printing from a transfer sheet. Printing by a printing method can be repeated to obtain a colored layer 40 having a desired thickness. Examples of the ink used in the printing method include inks containing a colorant, a binder, a solvent, and an optional additive. From the viewpoint of reducing the level difference, the colored layer 40 is preferably formed partially on the surface of the back surface plate 30 on the 2 nd adhesive layer 22 side.

Examples of the binder include chlorinated polyolefins (e.g., chlorinated polyethylene and chlorinated polypropylene), polyester resins, polyurethane resins, acrylic resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, and cellulose resins. The binder resin may be used alone, or 2 or more kinds may be used in combination. The binder resin may be a thermally polymerizable resin or a photopolymerizable resin.

When the colorant-containing layer is formed by a printing method, the colorant is preferably an ink containing 50 to 200 parts by mass per 100 parts by mass of the binder resin.

Specific examples of the plating method include known plating methods such as electroplating, electroless plating, hot dip plating, chemical vapor deposition, and physical vapor deposition. Examples of physical vapor deposition include an evaporation system including a method of heating an evaporation source to evaporate, such as vacuum vapor deposition, molecular beam vapor deposition, or ion beam vapor deposition, and sputtering thoracodynia, such as magnetron sputtering or ion beam sputtering. These methods may be combined with patterning as desired. In this specification, a layer formed by the plating method is referred to as a plating layer.

When the colored layer 40 is provided on the peripheral edge portion of the front panel 10 or the back panel 30, the form of the colored layer is not limited to the form of the colored layer provided on the entire periphery of the peripheral edge portion, and may be a form of the colored layer provided only on a part of the peripheral edge portion depending on a desired design or the like. When the colored layer 40 is provided on the peripheral edge portion of the front panel 10 or the back panel 30, the width thereof may be appropriately determined depending on the size of the display region, the desired design, and the like, and is preferably in the range of, for example, 1mm to 20 mm.

The thickness of the colored layer 40 may be, for example, 50 μm or less, preferably 30 μm or less, and more preferably 25 μm or less. When the thickness of the colored layer 40 is within the above numerical range, bubbles tend to be easily suppressed from being generated at the interface with the pressure-sensitive adhesive layer. The thickness of the colored layer 40 may be, for example, 0.1 μm or more, and preferably 3 μm or more. When the thickness of the colored layer 40 is 0.1 μm or more, the colored layer 40 is easily visually recognized, which contributes to improvement of design and improvement of optical density.

In fig. 1, the colored layer 40 is illustrated as having a uniform thickness and a rectangular cross-sectional shape, but the colored layer 40 may have a non-uniform thickness and may have a cross-sectional shape having a tapered portion with a thickness decreasing inward, for example. By having the tapered portion, air suction which is likely to occur during lamination tends to be easily suppressed. When the thickness of the colored layer 40 is not uniform, the numerical range described above as the thickness of the colored layer 40 is the maximum thickness of the colored layer 40.

< display device >

A display device according to another embodiment of the present invention includes a laminate 100. The laminate 100 may be disposed on the viewing side of the display device so that the front panel is on the outside. 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. The laminate 100 is suitable for a display device having flexibility.

< method for producing laminate >

Embodiment 1 of the method for manufacturing the laminate 100 includes the following steps.

1) Step of forming colored layer 40 partially on one surface of rear plate 30 (FIG. 2(a))

2) Preparation of adhesive sheet 2 having adhesive layer 2 22 between release film 61 and release film 62 (FIG. 2(b))

3) A step of peeling off the release film 62 and bonding the 2 nd adhesive sheet 60 to the surface of the back plate 30 on the side of the colored layer 40 (FIG. 2(c))

4) Step (D) of preparing 1 st adhesive sheet 70 having 1 st adhesive layer 21 between release film 71 and release film 72 (FIG. 2)

5) A step of bonding the 2 nd pressure-sensitive adhesive layer 22 of the 2 nd pressure-sensitive adhesive sheet 60 from which the release film 61 has been peeled and the 1 st pressure-sensitive adhesive layer 21 of the 1 st pressure-sensitive adhesive sheet 70 from which the release film 72 has been peeled (FIG. 2(e))

6) A step of peeling off the release film 71 and bonding the front plate 10 to the surface of the 1 st pressure-sensitive adhesive layer 21 (FIG. 2(f))

Embodiment 2 of the method for manufacturing the laminate 100 includes the following steps.

1) Step of forming colored layer 40 partially on one surface of rear plate 30 (FIG. 3(a))

2) Preparation of adhesive sheet 2 having adhesive layer 2 22 between release film 61 and release film 62 (FIG. 3(b))

3) A step of peeling off the release film 62 and bonding the 2 nd adhesive sheet 60 to the surface of the back plate 30 on the side of the colored layer 40 (FIG. 3(c))

4) Step (D) of preparing 1 st adhesive sheet 70 having 1 st adhesive layer 21 between release film 71 and release film 72 (FIG. 3)

5) A step of peeling the release film 72 and bonding the 1 st adhesive sheet 70 to the surface of the front plate 10 (FIG. 3(e))

6) Step of bonding the 2 nd pressure-sensitive adhesive layer 22 of the 2 nd pressure-sensitive adhesive sheet 60 from which the release film 61 was peeled and the 1 st pressure-sensitive adhesive layer 21 of the 1 st pressure-sensitive adhesive sheet 70 from which the release film 71 was peeled (FIG. 3(f))

When the 1 st adhesive layer 21 and the 2 nd adhesive layer 22 are laminated or when the adhesive layer 20 is bonded to the front panel 10 or the back panel 30, a treatment such as corona treatment or plasma treatment may be applied to the bonding surface.

The 1 st adhesive sheet 70 and the 2 nd adhesive sheet 60 can be produced, for example, by: the pressure-sensitive adhesive composition is dissolved or dispersed in an organic solvent such as toluene or ethyl acetate to prepare a pressure-sensitive adhesive liquid, a layer made of a pressure-sensitive adhesive is formed in a sheet form on the release film 71 or 72 and the release film 61 or 62 subjected to the release treatment, and the other release film 72 or 71 and the release film 62 or 61 are further bonded to the pressure-sensitive adhesive layer.

In embodiments 1 and 2 of the method of manufacturing the laminate 100, in step 1), instead of forming the colored layer 40 partially on one surface of the back surface plate 30, the colored layer 40 may be formed partially on one surface of the front surface plate 10.

The present invention will be further specifically described with reference to examples and comparative examples, but the present invention is not limited to these examples.

Examples

< thickness >

The laminate was cut using a laser cutter. The cross section of the cut laminate was observed with a transmission electron microscope (SU 8010; manufactured by horiba, Ltd.), and the thickness of each layer was measured from the obtained observation image.

< storage elastic modulus >

The storage elastic modulus (G') of a sample obtained by stacking adhesive layers so as to have a thickness of 150 μm was measured under the following conditions using a rheometer (Anton Parr, MCR-301).

Conditions are as follows: stress 1%, frequency 1Hz

< loss tangent >

Tan. delta. was measured under the following conditions using a rheometer (Anton Parr, MCR-301) for a sample in which an adhesive layer was laminated so as to have a thickness of 150. mu.m.

Conditions are as follows: stress 1%, frequency 1Hz

< bendability >

After the laminate was fixed to a bending tester (Covotech, CFT-720C), a bending test was performed so that the distance between the films when the window film was bent was 6mm, with the window film being on the inner side. Thereafter, the number of times of bending when cracks were generated in the bent portion and the adhesive floated was determined as follows.

Very good: more than 20 ten thousand times, o: 10 ten thousand times or more and less than 20 ten thousand times, x: less than 10 ten thousand times

< evaluation of bubbles >

The laminate was left in an oven with 85 ℃ and 85% humidity for about 1 hour, and then taken out. The level difference portion of the level difference region of the colored layer was observed in a 1cm × 1cm region with an optical microscope, and the number of bubbles having a size of 10 μm or more was counted. Note that, the number in the column of "presence or absence of bubbles" in table 1 indicates the number of bubbles.

O: 10 of the following: more than 10

Production example 1-1 (acrylic copolymer A1)

In a 500ml 4-neck reactor in which nitrogen was refluxed and a cooling device was provided so as to easily adjust the temperature, 25 parts by weight of 4-hydroxybutyl acrylate (4-HBA), 50 parts by weight of 2-ethylhexyl acrylate (2-EHA), 15 parts by weight of Methyl Acrylate (MA), 10 parts by weight of isobornyl acrylate (IBOA) were charged, and then 100 parts by weight of ethyl acetate (EAc) as a solvent was charged. Thereafter, nitrogen purge was performed for 1 hour to remove oxygen, and then, the temperature was maintained at 60 ℃. After homogenizing the mixture, 0.07 part by mass of Azobisisobutyronitrile (AIBN) as a reaction initiator was added to 100 parts by mass of the mixture. The reaction was carried out for about 5 hours to obtain an acrylic copolymer A1 having a weight-average molecular weight of about 80 ten thousand.

Production examples 1-2 (acrylic copolymer A2)

An acrylic copolymer a2 was produced in the same manner as in production example 1-1, except that Butyl Acrylate (BA) was used instead of Methyl Acrylate (MA).

Production examples 1 to 3 (acrylic copolymer A3)

An acrylic copolymer A3 was produced in the same manner as in production example 1-1, except that Hexyl Acrylate (HA) was used instead of methyl acrylate.

Production examples 1 to 4 (acrylic copolymer A4)

An acrylic copolymer a4 was produced in the same manner as in production example 1-1, except that Lauryl Acrylate (LA) was used instead of methyl acrylate.

Production example 2-1 (acrylic copolymer B1)

In a 500ml 4-neck reactor refluxed with nitrogen gas and provided with a cooling device for easy adjustment, 20 parts by mass of Methyl Acrylate (MA), 40 parts by mass of 4-hydroxybutyl acrylate (4-HBA), and 40 parts by mass of Octyl Acrylate (OA) were charged, respectively, and then, nitrogen purging was performed for 1 hour in order to remove oxygen, and then, maintained at 80 ℃. After the mixture was uniformly mixed, 3 parts by mass of hydroxycyclohexyl phenyl ketone as a reactive photoinitiator was added to the mixture. Then, ultraviolet light (10mW) was irradiated with stirring to produce an acrylic copolymer B1.

Production example 2-2 (acrylic copolymer B2)

An acrylic copolymer B2 was produced in the same manner as in production example 2-1, except that 2-ethylhexyl acrylate (2-EHA) was used instead of methyl acrylate.

Production examples 2 to 3 (acrylic copolymer B3)

An acrylic copolymer B3 was produced in the same manner as in production example 2-1, except that Lauryl Acrylate (LA) was used instead of methyl acrylate.

(adhesive sheet 1)

A mixture in which 0.5 part by mass of a crosslinking agent (CORONATE-L, Tosoh Corp.) was added to 100 parts by mass of the acrylic copolymer shown in Table 1 was applied to the release film coated with the silicon release agent. The coated mixture was dried at 100 ℃ for 1 minute. The thickness after drying was 25 μm. A release film was bonded to the adhesive sheet to prepare a1 st adhesive sheet (177 mm in length × 105mm in width).

(No. 2 adhesive sheet)

A mixture of 10 parts by mass of a reactive diluent (isodecyl acrylate) and 0.1 part by mass of a photopolymerization initiator (hydroxycyclohexyl phenyl ketone) was added to 100 parts by mass of the acrylic copolymer shown in table 1, and the mixture was applied to a release film coated with a silicon release agent. A2 nd adhesive sheet (177 mm in length by 105mm in width) having a thickness of 25 μm was obtained by irradiating the sheet with a light amount shown in Table 1 using a high-pressure mercury UV lamp.

(preparation of composition for Forming coloring agent-containing layer (Black))

[ ink Components ]

Acetylene black 15% by mass

75% by mass of polyester

Dimethyl glutarate 2.5% by mass

Succinic acid 2% by mass

5.5% by mass of isophorone

[ curing agent ]

75% by mass of an aliphatic polyisocyanate

25% by mass of ethyl acetate

[ solvent ]

Isophorone

[ production method ]

The colorant layer-containing composition (black) was obtained by adding 10 parts by mass of the curing agent and 10 parts by mass of the solvent to 100 parts by mass of the ink components and stirring them.

(preparation of composition for Forming protective layer (transparent))

[ ink Components ]

90% by mass of polyester

Dimethyl glutarate 2.5% by mass

Succinic acid 2% by mass

5.5% by mass of isophorone

[ curing agent ]

75% by mass of an aliphatic polyisocyanate

25% by mass of ethyl acetate

[ solvent ]

Isophorone

[ production method ]

The curing agent 10 parts by mass and the solvent 10 parts by mass were added to 100 parts by mass of the ink components and stirred to obtain a composition for forming a protective layer.

(front panel)

As the front panel, a window film having a thickness of 70 μm (50 μm for the base film, 10 μm for each hard coat, 177mm in length × 105mm in width) in which hard coats were formed on both sides of the base film was prepared. The base film of the window film is a polyimide-based resin film, and the hard coat layer is a layer formed from a composition containing a dendritic compound having a polyfunctional acrylic group at the terminal.

(Back plate)

As the back plate, a circularly polarizing plate produced as follows was used.

After a photo-alignment film was formed on a substrate, a composition containing a dichroic dye and a polymerizable liquid crystal compound was applied on the substrate, and the composition was aligned and cured to obtain a polarizer having a thickness of 2 μm. A triacetyl cellulose (TAC) film having a thickness of 25 μm was bonded to the polarizer via an adhesive layer. A retardation film (thickness: 17 μm, layer constitution: overcoat layer (cured layer of acrylic resin composition, thickness: 1 μm)/pressure-sensitive adhesive layer (thickness: 5 μm)/lambda/4 plate (thickness: 3 μm)/pressure-sensitive adhesive layer (thickness: 5 μm)/positive C plate (thickness: 3 μm) comprising layer(s) cured with liquid crystal compound and orientation film) comprising a layer(s) polymerized and cured with liquid crystal compound was laminated on the surface exposed by peeling off the substrate. A circularly polarizing plate ("TAC/polarizer/retardation film" layer configuration, thickness 44 μm, longitudinal 177 mm. times. transverse 105mm) fabricated in this manner was prepared as a back plate. The angle between the absorption axis of the polarizer and the slow axis of the λ/4 plate is 45 °.

(laminated body)

After peeling off the release film on one side of the 2 nd adhesive sheet, corona treatment was applied to the exposed 2 nd adhesive layer.

On the surface of TAC of the circularly polarizing plate, the prepared colorant layer-containing composition (black) was used as an ink, and printing was performed by screen printing using a 460-mesh screen, the coating thickness after drying being a discharge amount of 3 μm, and a black printed layer having a thickness of 3 μm and a width of 5mm was formed on the non-display region.

On the TAC surface of the circularly polarizing plate having the black printed layer formed thereon, TiO was deposited by an electron beam deposition apparatus (product name: UNIVAC2050, manufactured by UNIVAC corporation)₂As a vapor deposition source, is formedA vapor deposition layer of the thickness of (1), on which In is formed as a vapor deposition sourceOn which TiO is deposited₂As a vapor deposition source, is formedA vapor deposition layer of thickness of (1), on which Al is deposited₂O₃As a vapor deposition source, is formedThe thickness of (3) is as small as possible. In this manner, a gold vapor-deposited layer (plating layer, thickness < 1 μm) composed of 4 layers was formed over the entire region including the non-display region and the display region.

Then, the protective layer was formed by printing using the prepared protective layer forming composition (transparent) as an ink on the non-display region of the surface of the gold vapor-deposited layer with a discharge amount of 5 μm in the coating thickness after drying by screen printing using a 460-mesh screen, and the gold vapor-deposited layer was removed by etching in the region where the protective layer was not formed (display region). In this way, the colored layer 40 of the layer composition (the entire thickness is more than 8 μm and less than 9 μm) of "black printed layer (thickness 3 μm)/gold vapor-deposited layer (thickness < 1 μm)/protective layer (thickness 5 μm)" is formed in the non-display area.

The surface of the circularly polarizing plate on the black print layer side is subjected to corona treatment. The 2 nd adhesive layer was bonded to the circularly polarizing plate so that the corona-treated surface was a bonding surface.

After peeling the release film of the other side of the 2 nd adhesive sheet, corona treatment was applied to the exposed 2 nd adhesive layer. The 1 st adhesive layer in the 1 st adhesive sheet was subjected to corona treatment. The 2 nd adhesive layer and the 1 st adhesive layer were bonded so that the corona-treated surfaces were bonding surfaces.

The release film was peeled from the 1 st adhesive sheet, and corona treatment was applied to the exposed 1 st adhesive layer. A corona treatment is applied to one side of the window film. The 1 st adhesive layer was bonded to the window film so that the corona-treated surface was a bonding surface.

A laminate composed of a window film/1 st adhesive layer/2 nd adhesive layer/circularly polarizing plate was produced in this manner.

The corona treatment was carried out under the following conditions.

Frequency: 20 kHz/Voltage: 8.6 kV/power: 2.5 kW/speed: 6 m/min

[ Table 1]

< modulus of elasticity under compression >

A sample for measurement (size 50 mm. times.50 mm) was cut out of the adhesive layer used in each of the examples and comparative examples. The measurement sample was tested at a measurement temperature of 25 ℃ in accordance with ISO-FDIS 14577-12013 (E) using a micro hardness tester (HM-500, manufactured by Helmut Fischer Co., Ltd., indenter type: diamond regular quadrangular pyramid) so that the pressing direction of the indenter was perpendicular to the main surface (the surface perpendicular to the thickness direction) of the measurement sample. Even when the measurement is performed such that the pushing direction of the indenter is perpendicular to the side surface (the surface parallel to the thickness direction) of the measurement sample, the measurement value is the same as the measurement performed such that the pushing direction of the indenter is perpendicular to the main surface of the measurement sample.

The indenter was unloaded by applying a load after contacting the measurement sample, and holding the indenter for 5 seconds after reaching a set test force (1 mN). The slope of the tangent line at the maximum test force was obtained from the stress-strain curve obtained at the time of unloading, and the slope was used as the compressive modulus of elasticity (E' ═ δ/∈). The results are shown in Table 2.

[ Table 2]

Description of the symbols

10 front panel, 21 st adhesive layer, 1 st adhesive layer, 61, 62, 71, 72 release film, 70 st adhesive sheet, 1 nd adhesive layer, 22 nd adhesive layer, 60 nd adhesive sheet, 2 nd adhesive sheet, 30 back panel, 40 colored layer, 100 laminated body.