CN115335736A

CN115335736A - Laminated body

Info

Publication number: CN115335736A
Application number: CN202180022784.6A
Authority: CN
Inventors: 金东辉; 金恩瑛; 柳智熙
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2020-03-23
Filing date: 2021-03-18
Publication date: 2022-11-11
Also published as: KR20220157367A; WO2021193348A1; JP2021152650A; TW202136832A

Abstract

The purpose of the present invention is to provide a laminate having excellent bendability, said laminate comprising, in order, a 1 st optical component, a 1 st adhesive layer, a linear polarizing plate, a retardation plate, and a 2 nd optical component. The present invention provides a laminate comprising a 1 st optical member, a 1 st adhesive layer, a linearly polarizing plate, a retardation plate and a 2 nd optical member in this order, wherein the linearly polarizing plate comprises a protective layer and a polarizer in this order from the 1 st optical member side, the retardation plate comprises a 1 st retardation layer and a 2 nd retardation layer in this order from the 1 st optical member side, and the 1 st retardation layer and the 2 nd retardation layer are bonded to each other through an interlayer bonding layer, and the conditions A and B are satisfied.

Description

Laminated body

Technical Field

The present invention relates to a laminate, and further relates to an image display device including the laminate.

Background

Patent document 1 discloses a laminate for a flexible image display device including an adhesive layer and an optical film, wherein a storage elastic modulus G 'at 25 ℃ of the adhesive layer on the outermost surface of the convex side when the laminate is bent is substantially the same as or smaller than a storage elastic modulus G' at 25 ℃ of another adhesive layer.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-028573

Disclosure of Invention

In a laminate comprising a 1 st optical member, a 1 st pressure-sensitive adhesive layer, a linearly polarizing plate, a retardation plate, and a 2 nd optical member in this order, when the laminate is bent with the 1 st optical member side being inside at room temperature, cracks may easily occur in the retardation layer of the retardation plate. When the 1 st optical member is bent with the side thereof facing the inside at low temperature, peeling may easily occur between the 1 st optical member and the linearly polarizing plate.

The purpose of the present invention is to provide a laminate having excellent bendability at room temperature, said laminate comprising, in order, a 1 st optical member, a 1 st adhesive layer, a linearly polarizing plate, a retardation plate, and a 2 nd optical member.

Another object of the present invention is to provide a laminate having excellent flexibility at a temperature of-20 ℃, the laminate comprising, in order, a 1 st optical member, a 1 st adhesive layer, a linear polarizing plate, a retardation plate, and a 2 nd optical member.

It is still another object of the present invention to provide a laminate having excellent bendability at any temperature of room temperature and-20 ℃, the laminate comprising, in order, a 1 st optical member, a 1 st adhesive layer, a linearly polarizing plate, a retardation plate, and a 2 nd optical member.

The invention provides the following laminated body and image display device.

[1] A laminate comprising a 1 st optical member, a 1 st adhesive layer, a linearly polarizing plate, a retardation plate, and a 2 nd optical member in this order,

the above-mentioned linear polarizing plate comprises a protective layer and a polarizer in this order from the 1 st optical member side,

the retardation plate comprises a 1 st retardation layer and a 2 nd retardation layer in this order from the 1 st optical member side,

the 1 st retardation layer and the 2 nd retardation layer are bonded to each other via an interlayer bonding layer,

the following conditions a and B are satisfied.

Condition a: the rigidity (a) of the 1 st pressure-sensitive adhesive layer at room temperature is 3 MPa. Mu.m or less.

Condition B: the ratio (b/c) of the rigidity (b) of the protective layer at room temperature to the rigidity (c) of the interlayer adhesive layer at room temperature is 1 ten thousand or less.

[2] The laminate according to [1], wherein the following conditions A 'and B' are further satisfied.

Condition A': the first pressure-sensitive adhesive layer has a rigidity (a') of 10MPa μm or less at a temperature of-20 ℃.

Condition B': the ratio (b '/c') of the rigidity (b ') of the protective layer at a temperature of-20 ℃ to the rigidity (c') of the interlayer adhesive layer at a temperature of-20 ℃ is 1 thousand or less.

[3] A laminate comprising a 1 st optical member, a 1 st adhesive layer, a linearly polarizing plate, a retardation plate, and a 2 nd optical member in this order,

the following conditions a 'and B' are satisfied.

[4] The laminate according to any one of [1] to [3], further satisfying the following condition C.

Condition C: the rigidity (c) of the interlayer adhesive layer is 10 MPa-mum or more.

[5] The laminate according to any one of [1] to [4], wherein the 2 nd retardation layer has a layer containing a cured product of a polymerizable liquid crystal compound.

[6] The laminate according to any one of [1] to [5], wherein the interlayer bonding layer is an adhesive layer.

[7] The laminate according to any one of [1] to [6], wherein the 1 st optical member is a front panel and the 2 nd optical member is a touch sensor panel.

[8] An image display device comprising the laminate according to any one of [1] to [7 ].

According to the present invention, a laminate having excellent bendability can be provided, the laminate comprising, in order, a 1 st optical member, a 1 st adhesive layer, a linearly polarizing plate, a retardation plate, and a 2 nd optical member.

Drawings

Fig. 1 is a schematic cross-sectional view schematically showing an example of a laminate of the present invention.

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

Fig. 3 is a schematic diagram illustrating a method of the repeated bending test.

Fig. 4 is a schematic diagram illustrating a method of the static bending durability test.

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 following embodiments. In all the drawings below, the scale of each component is appropriately adjusted to facilitate understanding of the component, and the scale of each component shown in the drawings does not necessarily coincide with the scale of the actual component.

< laminate >

The laminate of the present invention is explained with reference to fig. 1. The laminate 100 shown in fig. 1 includes a 1 st optical member 110, a 1 st pressure-sensitive adhesive layer 120, a linearly polarizing plate 130, a retardation plate 140, and a 2 nd optical member 150 in this order. The laminate 100 may further include a bonding layer between the linear polarizer 130 and the phase difference plate 140, and between the phase difference plate 140 and the 2 nd optical member 150. The linearly polarizing plate 130 includes a protective layer 131 and a polarizer 132 in this order from the 1 st optical member 110 side. The linearly polarizing plate 130 may have an orientation film between the protective layer 131 and the polarizer 132. The retardation plate 140 includes a 1 st retardation layer 141 and a 2 nd retardation layer 142 in this order from the 1 st optical member 110 side, and the 1 st retardation layer 141 and the 2 nd retardation layer 142 are bonded by an interlayer bonding layer 143. Hereinafter, the 1 st optical component and the 2 nd optical component may be collectively referred to as an optical component.

The laminate 100 can be bent with the 1 st optical member 110 side as the inner side (hereinafter, also referred to as inner folding). The term "bendable" means that the laminate can be bent at either or both of normal temperature and temperature-20 ℃ without causing cracks in the retardation plate. The bending includes a bent form in which a curved surface is formed at a bent portion. In the form of the bend, the bend radius of the inner surface of the bend is not particularly limited. The bending includes a form in which the inner surface is bent at a bending angle of more than 0 ° and less than 180 °, and a form in which the inner surface has a bending radius of near zero or the inner surface has a bending angle of 0 °. The laminate of the present invention can be bent, and therefore is suitable for a flexible display. In the present specification, the inward folding means that the optical member is bent so as to be inward with respect to the layer 1 st optical member which is the center in the thickness direction of the laminate.

In the present specification, the normal temperature may be 23 ℃ to 25 ℃.

[ repeated bending durability ]

When the laminate 100 is repeatedly bent at either or both of normal temperature (e.g., 25 ℃) and-20 ℃ so that the 1 st optical member 110 side is inside and the bending radius is 1mm, the retardation plate 140 tends to be less likely to crack in the bent portion. When the laminate 100 is repeatedly bent at a bending radius of 1mm with the 1 st optical member 110 side as the inner side at either or both of room temperature (e.g., a temperature of 25 ℃) and a temperature of-20 ℃, the number of times of bending that the phase difference plate 140 initially cracks is preferably 10 ten thousand or more, more preferably 20 ten thousand or more, and still more preferably 30 ten thousand or more. The repeated bending durability test can be performed by the method described in the examples described later.

[ static bending durability ]

When the laminate 100 is bent with the 1 st optical member 110 side as the inside and the bending radius is 1mm, the phase difference plate 140 tends to be less likely to crack in the bent portion. When the laminate 100 is in a curved state with the 1 st optical member 110 side as the inner side and the bending radius of 1mm, the period until the phase difference plate 140 first cracks is preferably 20 days or longer, and more preferably 30 days or longer. The static bending durability test can be performed by the method described in the examples described later.

In the laminate 100, the number of times of bending when the phase difference plate 140 is initially cracked is preferably 10 ten thousand or more in the above repeated bending, and the period until the phase difference plate 140 is initially cracked in the above static bending durability test is 20 days or more, and more preferably, the number of times of bending when the phase difference plate 140 is initially cracked is 20 ten thousand or more in the above repeated bending, and the period until the phase difference plate 140 is initially cracked in the above static bending durability test is 30 days or more.

The laminate 100 has excellent bendability at normal temperature by satisfying both the condition a and the condition B. In the present specification, excellent bendability at ordinary temperature means excellent both of the above-described repeated bending durability and static bending durability at ordinary temperature. Even when the 2 nd retardation layer 142 has a layer containing a cured product of a polymerizable liquid crystal compound, which is relatively likely to cause cracking, the laminate 100 can exhibit excellent bendability.

[ Condition A ]

The rigidity (a) [ hereinafter, also referred to as rigidity (a) for simplicity ] of the 1 st pressure-sensitive adhesive layer 120 at room temperature is 3 MPa. Mu.m or less. When the rigidity (a) of the 1 st pressure-sensitive adhesive layer 120 is 3MPa · μm or less, good bendability tends to be easily obtained at normal temperature. This is presumably because: by disposing the 1 st adhesive layer 120, which is relatively flexible, between the 1 st optical member 110 and the linearly polarizing plate 130, the influence from the 1 st optical member 110 is less likely to be transmitted to the linearly polarizing plate 130 and, further, to the phase difference plate 140. The rigidity (a) is the product [ MPa.mu.m ] of the elastic modulus [ MPa ] and the thickness [ mu.m ] of the 1 st adhesive layer 120. The elastic modulus [ MPa ] for obtaining the rigidity (a) was measured for the storage elastic modulus [ MPa ] at ordinary temperature. The storage elastic modulus [ MPa ] and the thickness [ μm ] at room temperature were determined by the methods described in the section of examples, which will be described later. The preferable ranges of the elastic modulus [ MPa ] and the thickness [ μm ] of the 1 st adhesive layer 120 are described later.

From the viewpoint of excellent bendability of the laminate 100 at room temperature, the rigidity (a) of the 1 st pressure-sensitive adhesive layer 120 is preferably 2.5MPa · μm or less, more preferably 2.0MPa · μm or less, and even more preferably 1.5MPa · μm or less. The rigidity (a) of the first pressure-sensitive adhesive layer 120 is usually 0.001MPa · μm or more, for example, 0.005MPa · μm or more, or 0.01MPa · μm or more, or 0.05MPa · μm or more, or 0.1MPa · μm or more, or 0.5MPa · μm or more.

[ Condition B ]

The ratio (b/c) of the rigidity (b) of the protective layer 131 at room temperature [ hereinafter, also referred to as rigidity (b) for simplicity) to the rigidity (c) of the interlayer bonding layer 143 at room temperature [ hereinafter, also referred to as rigidity (c) for simplicity) ] is 1 ten thousand or less. When the ratio (b/c) is 1 ten thousand or less, good bendability tends to be easily obtained at normal temperature. This is presumably because: by increasing the rigidity of the interlayer bonding layer 143 bonding the 1 st retardation layer 141 and the 2 nd retardation layer 142, the 2 nd retardation layer 142 tends to be easily supported by the interlayer bonding layer 143, and by decreasing the rigidity of the protective layer 131 of the linear polarizer 130, stress applied to the 2 nd retardation layer 142 during bending tends to be reduced.

The ratio (b/c) is preferably 5000 or less, more preferably 1000 or less, further preferably 500 or less, may be 300 or less, and may be 200 or less. The ratio (b/c) is usually 0.001 or more, and may be, for example, 0.01 or more, or 0.1 or more, or 1 or more.

The rigidity (b) of the protective layer 131 may be, for example, 1000MPa · μm to 10 ten thousand MPa · μm, preferably 2000MPa · μm to 9 ten thousand MPa · μm, more preferably 5000MPa · μm to 8.5 ten thousand MPa · μm, or may be 1 ten thousand or less. When the rigidity (b) is within the above range, the laminate tends to have excellent bendability at normal temperature.

The rigidity (b) is the product [ MPa.mu.m ] of the elastic modulus [ MPa ] and the thickness [ mu.m ] of the protective layer 131. When the protective layer 131 is an inorganic layer or an organic layer described later, the elastic modulus [ MPa ] for obtaining the rigidity (b) is measured for the compressive elastic modulus [ MPa ] at room temperature. When the protective layer 131 is formed of a resin film described later, the tensile elastic modulus [ MPa ] at room temperature is measured with respect to the elastic modulus [ MPa ] for obtaining the rigidity (b). The compression elastic modulus [ MPa ] at room temperature, the tensile elastic modulus [ MPa ] at room temperature and the thickness [ μm ] were determined by the methods described in the section of examples, which will be described later. The preferable ranges of the elastic modulus [ MPa ] and the thickness [ μm ] of the protective layer 131 are described later.

The rigidity (c) of the interlayer 143 may be, for example, 10MPa · μm or more, preferably 30MPa · μm to 1 ten thousand MPa · μm, more preferably 100MPa · μm to 9000MPa · μm, and further preferably 1000MPa · μm to 6000MPa · μm. When the rigidity (c) is within the above range, the laminate 100 tends to have excellent flexibility.

The rigidity (c) is the product [ MPa · μm ] of the elastic modulus [ MPa ] and the thickness [ μm ] of the interlayer adhesive layer 143. When the interlayer adhesive layer 143 is an adhesive layer, the modulus of elasticity [ MPa ] for obtaining the rigidity (c) is measured as the modulus of elasticity [ MPa ] under compression at room temperature. When the interlayer bonding layer 143 is an adhesive layer, the elastic modulus [ MPa ] for obtaining the rigidity (c) is measured, and the storage elastic modulus [ MPa ] at room temperature is measured. The compression elastic modulus [ MPa ] at room temperature, the storage elastic modulus [ MPa ] at room temperature, and the thickness [ μm ] were determined by the methods described in the section of examples, which will be described later. The preferred ranges of the elastic modulus [ MPa ] and the thickness [ μm ] of the interlayer adhesive layer 143 will be described later.

The laminate 100 satisfies both the condition a 'and the condition B', and thus has excellent bendability at a temperature of-20 ℃. In the present specification, the fact that the flexibility is excellent at a temperature of-20 ℃ means that the above-mentioned repeated flexibility durability is excellent at a temperature of-20 ℃. Even when the 2 nd retardation layer 142 has a layer containing a cured product of a polymerizable liquid crystal compound, which is relatively susceptible to cracking, the laminate 100 can exhibit excellent bendability at a temperature of-20 ℃.

[ Condition A' ]

The rigidity (a ') [ hereinafter, also referred to as "rigidity (a')" for simplicity ] of the 1 st pressure-sensitive adhesive layer 120 at a temperature of-20 ℃ is 10 MPa. Mu.m or less. When the rigidity (a') is 10 MPa-. Mu.m or less, good bendability tends to be easily obtained at a temperature of-20 ℃. This is presumably because: by disposing the 1 st adhesive layer 120, which is relatively flexible, between the 1 st optical member 110 and the linearly polarizing plate 130, the influence from the 1 st optical member 110 is less likely to be transmitted to the linearly polarizing plate 130 and, further, to the phase difference plate 140. The rigidity (a') is the product [ MPa.mu.m ] of the elastic modulus [ MPa ] and the thickness [ mu.m ] of the 1 st adhesive layer 120 at a temperature of-20 ℃. The elastic modulus [ MPa ] for determining the rigidity (a') was measured as the storage elastic modulus [ MPa ] at a temperature of-20 ℃. The storage elastic modulus [ MPa ] and the thickness [ μm ] at a temperature of-20 ℃ were determined by the methods described in the section of examples, which will be described later. The preferable ranges of the elastic modulus [ MPa ] and the thickness [ μm ] of the 1 st adhesive layer 120 at a temperature of-20 ℃ are described below.

From the viewpoint of excellent bendability of the laminate 100 at a temperature of-20 ℃, the rigidity (a') is preferably 9MPa · μm or less, more preferably 7MPa · μm or less, and even more preferably 5MPa · μm or less. The rigidity (a') is usually 0.001 MPa.mu.m or more, for example, 0.005 MPa.mu.m or more, or 0.01 MPa.mu.m or more, or 0.05 MPa.mu.m or more, or 0.1 MPa.mu.m or more, or 0.5 MPa.mu.m or more.

[ Condition B' ]

The ratio (b '/c') [ hereinafter, also referred to as ratio (b '/c') ] between the rigidity (b ') of the protective layer 131 at-20 ℃ and the rigidity (c') of the interlayer bonding layer 143 at-20 ℃ is 1 thousand or less. When the ratio (b '/c') is 1 thousand or less, good bendability tends to be easily obtained at a temperature of-20 ℃. This is presumably because: by increasing the rigidity of the interlayer bonding layer 143 bonding the 1 st retardation layer 141 and the 2 nd retardation layer 142, the 2 nd retardation layer 142 tends to be supported by the interlayer bonding layer 143, and by decreasing the rigidity of the protective layer 131 of the linearly polarizing plate 130, stress applied to the 2 nd retardation layer 142 during bending tends to be decreased.

The ratio (b '/c') is preferably 500 or less, more preferably 400 or less, further preferably 300 or less, and may be 200 or less. The ratio (b '/c') is usually 0.001 or more, and may be, for example, 0.01 or more, or 0.1 or more, or 1 or more.

The rigidity (b') may be, for example, 1000MPa · μm to 10 ten thousand MPa · μm, preferably 2000MPa · μm to 9 ten thousand MPa · μm, more preferably 5000MPa · μm to 8.5 ten thousand MPa · μm, or may be 1 ten thousand or less. When the rigidity (b') is within the above range, the laminate tends to have excellent bendability at a temperature of-20 ℃.

The rigidity (b') is the product [ MPa · μm ] of the elastic modulus [ MPa ] and the thickness [ μm ] of the protective layer 131. When the protective layer 131 is formed of a resin film described later, the tensile elastic modulus [ MPa ] measured at a temperature of-20 ℃ is used as the elastic modulus [ MPa ] for obtaining the rigidity (b'). When the protective layer 131 is formed of a resin film described later, the tensile elastic modulus [ MPa ] measured at room temperature can be used as the tensile elastic modulus [ MPa ] measured at-20 ℃. When the protective layer 131 is an inorganic layer or an organic layer described later, the elastic modulus [ MPa ] for obtaining the rigidity (b') is a compressive elastic modulus [ MPa ], and the compressive elastic modulus [ MPa ] measured at room temperature is used because the compressive elastic modulus [ MPa ] cannot be measured at a temperature of-20 ℃. The tensile elastic modulus [ MPa ] at a temperature of-20 ℃, the compressive elastic modulus [ MPa ] at normal temperature and the thickness [ μm ] were determined by the methods described in the column of examples, which will be described later. The preferable ranges of the elastic modulus [ MPa ] and the thickness [ μm ] of the protective layer 131 are described later.

The rigidity (c') may be, for example, 10MPa · μm or more, preferably 30MPa · μm to 1 ten thousand MPa · μm, more preferably 100MPa · μm to 9000MPa · μm, and further preferably 1000MPa · μm to 6000MPa · μm. When the rigidity (c') is within the above range, the laminate 100 tends to have excellent bendability at a temperature of-20 ℃.

The rigidity (c') is the product [ MPa · μm ] of the elastic modulus [ MPa ] and the thickness [ μm ] of the interlayer adhesive layer 143. When the interlayer bonding layer 143 is an adhesive layer, the elastic modulus [ MPa ] for obtaining the rigidity (c') is the storage elastic modulus [ MPa ] measured at a temperature of-20 ℃. When the interlayer adhesive layer 143 is an adhesive layer, the elastic modulus [ MPa ] for obtaining the rigidity (c') is the compressive elastic modulus [ MPa ], and the compressive elastic modulus [ MPa ] measured at room temperature is used because the compressive elastic modulus [ MPa ] cannot be measured at-20 ℃. The storage elastic modulus [ MPa ] at a temperature of-20 ℃, the compression elastic modulus [ MPa ] at normal temperature and the thickness [ μm ] were determined by the methods described in the section of examples, which will be described later. The preferable ranges of the elastic modulus [ MPa ] and the thickness [ μm ] of the interlayer adhesive layer 143 are described below.

The laminate 100 may have, for example, a square shape in a plan view, preferably a square shape having long sides and short sides, and more preferably a rectangular shape. Each layer constituting the laminate 100 may be subjected to R processing on the corners, or to slitting processing on the ends, or to hole forming processing.

The laminate 100 can be used in, for example, an image display device. The image 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 laminate 100 is flexible, and thus is suitable for a flexible display.

[ optical component ]

The optical member may be a component used in a general image display device. When the laminate 100 is used in an image display device, it can be bonded to the image display device so that the 1 st optical member 110 is on the viewing side, and preferably, the 1 st optical member 110 is bonded to the image display device so that it becomes the outermost layer constituting the viewing side of the image display device.

Examples of the optical member include a front panel, a touch sensor panel, and an image display element. The 1 st optical member 110 may be a front panel. The 2 nd optical member 150 may be a touch sensor panel or an image display element, and is preferably a touch sensor panel.

[ front panel ]

The front panel is not limited in material and thickness as long as it is a plate-like body that can transmit light, and may have a single-layer structure or a multilayer structure, and examples thereof include a glass plate-like body (e.g., a glass plate, a glass film, etc.) and a resin plate-like body (e.g., a resin plate, a resin sheet, a resin film, etc.). The front panel may be a layer constituting the outermost surface of the image display device on the viewing side.

As the glass plate, strengthened glass for display is preferably used. The thickness of the glass plate is, for example, 10 to 1000. Mu.m, preferably 20 to 500. Mu.m. By using the glass plate, an optical member having excellent mechanical strength and surface hardness can be constituted.

The resin film is not limited as long as it is a resin film that can transmit light. Examples of the film include films formed 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, poly (meth) methyl acrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, and polyamideimide. These polymers may be used alone or in combination of 2 or more. When the laminate is used for a flexible display, a resin film made of a polymer such as polyimide, polyamide, or polyamideimide, which can be configured to have excellent flexibility, high strength, and high transparency, is preferably used. In the present specification, "(meth) acrylic" means either acrylic or methacrylic. The "(meth)" of (meth) acrylate and the like also has the same meaning.

When the front panel is a resin film, the resin film may be a film having a hard coat layer provided on at least one surface of the base film to further increase the hardness. The hard coat layer may be formed on one surface of the substrate film or on both surfaces. When the image display device described later is a touch panel type image display device, the surface of the front panel is a touch surface, and therefore a resin film having a hard coat layer is preferably used. A resin film having improved hardness and scratch resistance can be produced by providing a hard coat layer. The hard coat layer is a cured layer of, for example, an ultraviolet curable resin. Examples of the ultraviolet curable resin include (meth) acrylic resins, silicone resins, polyester resins, polyurethane resins, amide resins, and epoxy resins. The hard coating may contain additives for increasing hardness. The additive is not limited, and examples thereof include inorganic fine particles, organic fine particles, and a mixture thereof. The thickness of the resin film is, for example, 30 to 2000. Mu.m.

The front panel may have a function of protecting the front surface of the image display device, a function as a touch sensor, a blue light cut-off function, a view angle adjustment function, and the like.

[1 st adhesive layer ]

The 1 st adhesive layer 120 may be a layer interposed between the 1 st optical member 110 and the linear polarizer 130 to attach them. The "adhesive agent" in the present specification means a substance which is in a state of a high-viscosity liquid or gel-like solid after a curing reaction and can be adhered by applying a slight pressure at normal temperature for a short time, and is also referred to as a pressure-sensitive adhesive, for example. On the other hand, the term "adhesive" as used herein refers to an adhesive other than an adhesive (pressure-sensitive adhesive), and is an adhesive which is solid after a curing reaction and has an elastic modulus in a range of 100MPa or more after curing. The 1 st adhesive layer 120 may be 1 layer, or may be composed of 2 or more layers, and preferably 1 layer.

The storage elastic modulus [ MPa ] of the 1 st pressure-sensitive adhesive layer 120 at room temperature may be, for example, 0.005MPa to 1MPa, preferably 0.01MPa to 0.5MPa, or 0.1MPa or less. The storage elastic modulus [ MPa ] of the 1 st pressure-sensitive adhesive layer 120 at room temperature can be adjusted by, for example, selecting the kind of monomer used in the pressure-sensitive adhesive composition described later, adjusting the crosslinking degree, and the like.

The storage elastic modulus [ MPa ] of the first pressure-sensitive adhesive layer 120 at a temperature of-20 ℃ may be, for example, 0.01MPa to 20MPa, preferably 0.05MPa to 15MPa, or 10MPa or less. The storage elastic modulus [ MPa ] of the 1 st pressure-sensitive adhesive layer 120 at a temperature of-20 ℃ can be adjusted by, for example, selecting the kind of monomer used in the pressure-sensitive adhesive composition described later, adjusting the degree of crosslinking, and the like.

The thickness of the 1 st adhesive layer 120 is preferably 4 μm or more, more preferably 5 μm or more, and further preferably 10 μm or more. From the viewpoint of improving the flexibility, the thickness of the pressure-sensitive adhesive layer 150 is preferably 100 μm or less, and more preferably 50 μm or less. The thickness of the 1 st adhesive layer 120 is the maximum thickness of the 1 st adhesive layer 120.

The 1 st pressure-sensitive adhesive layer 120 may be composed of a pressure-sensitive adhesive composition containing a resin such as a (meth) acrylic, rubber, urethane, ester, silicone, or polyvinyl ether resin as a main component. Among them, preferred is an adhesive composition containing a (meth) acrylic resin as a base polymer, which is excellent in transparency, weather resistance, heat resistance and the like. The adhesive composition may be an active energy ray-curable adhesive composition or a thermosetting adhesive composition.

As the (meth) acrylic resin (base polymer) used in the pressure-sensitive adhesive composition, for example, a polymer or copolymer using 1 or 2 or more (meth) acrylic acid esters such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate as monomers is preferably used. The base polymer may be copolymerized with a polar monomer. 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, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylamide, N-dimethylaminoethyl (meth) acrylate, and glycidyl (meth) acrylate.

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

The active energy ray-curable adhesive composition is an 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 being capable of being adhered to an adherend such as a film with adhesiveness even before irradiation with an active energy ray and being cured by irradiation with an active energy ray to adjust the adhesion 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 necessary.

The binder composition 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, anticorrosive agents, and photopolymerization initiators for imparting light scattering properties.

The 1 st adhesive layer 120 can be formed by applying a diluted solution of the adhesive composition in an organic solvent to a substrate and drying the applied solution. When an active energy ray-curable adhesive composition is used, the formed 1 st adhesive layer can be irradiated with an active energy ray to obtain a cured product having a desired degree of curing.

[ Linear polarizing plate ]

The linear polarizer 130 may be a laminate of a protective layer 131 on one side of the polarizer 132. The linearly polarizing plate 130 has a property of transmitting linearly polarized light having a vibration plane perpendicular to the absorption axis when unpolarized light enters. The linearly polarizing plate 130 may include a polyvinyl alcohol (hereinafter, may be abbreviated as "PVA") resin film as the polarizer 132, or may be a cured film obtained by aligning a composition including a dichroic dye and a polymerizable compound and polymerizing the polymerizable liquid crystal compound. A polarizer obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound is preferable because the bending direction is not limited as compared with a polarizer containing a PVA-based resin film obtained by a stretching step.

The linearly polarizing plate 130 may include only the polarizer 132 and the protective layer 131, or may further include one or more of a substrate, a thermoplastic resin film, an overcoat layer, and an alignment film in addition to the polarizer 132 and the protective layer 131. The thickness of the linearly polarizing plate 130 is, for example, 2 μm to 100 μm, preferably 5 μm to 60 μm.

[ polarizer ]

Examples of the polarizer 132 include films obtained by subjecting hydrophilic polymer films such as polyvinyl alcohol (hereinafter, also abbreviated as "PVA") based films, partially formalized PVA based films, and ethylene-vinyl acetate copolymer partially saponified films to a dyeing treatment with a dichroic substance such as iodine or a dichroic dye, and a stretching treatment. Since the optical characteristics are excellent, the polarizer 132 obtained by dyeing a PVA-based resin film with iodine and uniaxially stretching the same is preferable.

The polyvinyl alcohol resin can be produced by saponifying a polyvinyl acetate resin. The polyvinyl acetate resin may be a copolymer of vinyl acetate and another monomer copolymerizable with vinyl acetate, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. 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 polyvinyl alcohol resin has an average polymerization degree of usually about 1000 to 10000, preferably 1500 to 5000. The average polymerization degree of the polyvinyl alcohol resin can be determined in accordance with JIS K6726 (1994). When the average polymerization degree is less than 1000, it is difficult to obtain a desired polarizing performance, and when it exceeds 10000, film processability may be poor.

As another method for producing a polarizer including a PVA-based resin film, there is a production method including a step of preparing a base film, applying a solution of a resin such as a polyvinyl alcohol-based resin on the base film, and drying the solution to remove the solvent to form a resin layer on the base film. The primer layer may be formed in advance on the resin layer-forming surface of the substrate film. As the base film, a resin film such as PET or a film obtained by using a thermoplastic resin that can be used for a protective layer described later can be used. Examples of the material of the primer layer include a resin obtained by crosslinking a hydrophilic resin used for a polarizer.

Next, the amount of solvent such as water in the resin layer is adjusted as necessary, and then the base film and the resin layer are uniaxially stretched, and then the resin layer is dyed with a dichroic dye such as iodine to adsorb and orient the dichroic dye in the resin layer. Next, a washing step of treating the resin layer adsorbed and aligned with the dichroic dye with an aqueous boric acid solution and washing off the aqueous boric acid solution is performed as necessary. Thus, a polarizer, which is a resin layer having a dichroic dye adsorbed and oriented, is produced. The respective steps may be performed by known methods.

The uniaxial stretching of the base film and the resin layer may be performed before dyeing, during boric acid treatment after dyeing, or in each of the above-described plurality of stages. The substrate film and the resin layer may be uniaxially stretched in the MD direction (film transport direction), and in this case, the uniaxial stretching may be performed between rolls having different peripheral speeds, or the uniaxial stretching may be performed using a heat roll. In addition, the substrate film and the resin layer may be uniaxially stretched in the TD direction (direction perpendicular to the film transfer direction), and in this case, a so-called tenter method may be used. The stretching of the base film and the resin layer may be dry stretching in which the stretching is performed in the air, or may be wet stretching in which the stretching is performed in a state in which the resin layer is swollen with a solvent. In order to exhibit the performance of the polarizer, the stretching magnification is 4 times or more, preferably 5 times or more, and particularly preferably 5.5 times or more. The upper limit of the stretch ratio is not particularly limited, but is preferably 8 times or less from the viewpoint of suppressing breakage or the like.

The thickness of the polarizer containing the PVA based resin film is, for example, 2 to 40 μm. The thickness of the polarizer may be 5 μm or more, 20 μm or less, 15 μm or less, and 10 μm or less.

Examples of the method for producing a polarizer, which is a cured film obtained by aligning a composition containing a dichroic dye and a polymerizable compound and polymerizing the polymerizable liquid crystal compound, include a method for forming a polarizer by applying a composition for forming a polarizer, which contains a polymerizable liquid crystal compound and a dichroic dye, onto a base film via an alignment film, and a method for forming a polarizer by applying a composition for forming a polarizer, which contains a polymerizable liquid crystal compound and a dichroic dye, onto a protective layer 131, which will be described later, formed on a base film via an alignment film, and polymerizing and curing the polymerizable liquid crystal compound while maintaining a liquid crystal state. The polarizer thus obtained is in a state of being laminated on the protective layer of the base film, and can be used as a linear polarizing plate with a base film. As the substrate film, a thermoplastic resin film, for example, a polyethylene terephthalate film, or the like can be used.

As the dichroic dye, may beThe dye having a property that the absorbance of the molecule in the major axis direction is different from the absorbance in the minor axis direction is used, and for example, the dye having the maximum absorption wavelength (λ max) in the range of 300 to 700nm is preferable. Examples of such dichroic dyes include acridine dyes,

Oxazine pigments, cyanine pigments, naphthalene pigments, azo pigments, anthraquinone pigments, and the like, and among them, azo pigments are preferable. Examples of the azo dye include monoazo dyes, disazo dyes, trisazo dyes, tetraazo dyes, and stilbene azo dyes, and disazo dyes and trisazo dyes are more preferable.

The composition for forming a polarizer may contain a solvent, a polymerization initiator such as a photopolymerization initiator, a photosensitizer, a polymerization inhibitor, and the like. Known substances such as a polymerizable liquid crystal compound, a dichroic dye, a solvent, a polymerization initiator, a photosensitizer, and a polymerization inhibitor contained in the composition for forming a polarizing layer can be used, and for example, substances exemplified in japanese patent application laid-open nos. 2017-102479 and 2017-83843 can be used. As the polymerizable liquid crystal compound, those exemplified as polymerizable liquid crystal compounds for obtaining a cured layer as a retardation layer described later can be used. The method for forming a polarizer by using the composition for forming a polarizer can also employ the method exemplified in the above publication.

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

An overcoat layer (hereinafter, also referred to as an OC layer) may be provided on the polarizer 132 side of the linearly polarizing plate 130. Examples of the material constituting the OC layer include a photocurable resin and a water-soluble polymer. Examples of the photocurable resin include a (meth) acrylic resin, a polyurethane resin, a (meth) acrylic polyurethane resin, an epoxy resin, and a silicone resin. Examples of the water-soluble polymer include poly (meth) acrylamide polymers; polyvinyl alcohol, and vinyl alcohol polymers such as 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, or may be 0.5 μm or more.

The polarizer produced by the above method can be used as a linear polarizer by peeling off the substrate film or by using the substrate film together with the substrate film. According to the above method, the base film can be peeled, and thus the polarizer can be further thinned.

[ protective layer ]

The protective layer 131 has a function of protecting the surface of the polarizer 132. In the laminate, the linearly polarizing plate 130 may be generally disposed so that the protective layer 131 is positioned on the 1 st optical member 110 side with respect to the polarizer 132.

The protective layer 131 may have an elastic modulus [ MPa ] of, for example, 100MPa to 1 ten thousand MPa, preferably 500MPa to 5000MPa. When the protective layer 131 is a resin film, the tensile elastic modulus [ MPa ] of the protective layer 131 at room temperature may be, for example, 100MPa to 1 ten thousand MPa. When the protective layer 131 is a resin film, the tensile elastic modulus [ MPa ] of the protective layer 131 at a temperature of-20 ℃ may be, for example, 50MPa to 1 ten thousand MPa. When the protective layer 131 is an inorganic layer or an organic layer, the compressive modulus of elasticity [ MPa ] of the protective layer 131 at room temperature may be, for example, 100MPa to 1 ten thousand MPa.

The elastic modulus [ MPa ] of the protective layer 131 can be adjusted by, for example, selecting a material for forming the protective layer 131.

The protective layer 131 may be an organic layer or an inorganic layer. The organic layer or the inorganic layer may be a layer formed by coating. The organic layer can be formed using a composition for forming a protective layer, for example, a (meth) acrylic resin composition, an epoxy resin composition, a polyimide resin composition, or the like. The composition for forming a protective layer may be an active energy ray-curable composition or a thermosetting composition. The inorganic layer may be formed of, for example, silicon oxide or the like. When the protective layer 131 is an organic layer, the protective layer may be referred to as a hard coat layer.

When the protective layer 131 is an organic layer, for example, a protective layer can be produced by applying an active energy ray-curable protective layer-forming composition to a substrate film and curing the composition by irradiation with active energy. The substrate film can be the one described above. The substrate film is usually peeled off. Examples of a method for applying the composition for forming a protective layer include spin coating. When the protective layer 131 is an inorganic layer, the protective layer can be formed by, for example, a sputtering method, an evaporation method, or the like. When the protective layer 131 is an organic layer or an inorganic layer, the thickness of the protective layer 131 may be, for example, 0.1 to 10 μm, and preferably 0.5 to 5 μm.

As the protective layer 131, for example, a thermoplastic resin film excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, stretchability, and the like can be used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyether sulfone resin; polysulfone resin; a polycarbonate resin; polyamide resins such as nylon and aromatic polyamide; a polyimide resin; polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; cyclic polyolefin resins having a cyclic norbornene structure (also referred to as norbornene-based resins); (meth) acrylic resins; a polyarylate resin; a polystyrene resin; polyvinyl alcohol resins, and mixtures thereof. When protective layers are laminated on both surfaces of the polarizer, the two protective layers may be of the same type or of different types. The thickness of the thermoplastic resin film may be, for example, 3 to 50 μm, preferably 5 to 30 μm.

[ phase difference plate ]

The laminate 100 may have a function as a circularly polarizing plate by including the linearly polarizing plate 130 and the phase difference plate 140. Hereinafter, the configuration including the linear polarizer 130 and the retardation plate 140 may be referred to as a circular polarizer.

The retardation plate 140 includes a 1 st retardation layer 141 and a 2 nd retardation layer 142. The 1 st retardation layer 141 and the 2 nd retardation layer 142 are bonded by an interlayer bonding layer 143 to be described later. The 1 st retardation layer 141 and the 2 nd retardation layer 142 may have an overcoat layer protecting the surfaces thereof, a substrate film supporting the 1 st retardation layer 141 and the 2 nd retardation layer 142, and the like. Examples of the 1 st retardation layer 141 and the 2 nd retardation layer 142 include a retardation layer providing a retardation of λ/4 (λ/4 layer), a retardation layer providing a retardation of λ/2 (λ/2 layer), and a positive C layer. The phase difference plate 140 preferably includes a positive C layer.

The retardation plate 140 is formed by laminating a 1 st retardation layer 141 and a 2 nd retardation layer 142 in this order from the linear polarizer side. When the retardation plate 140 includes a positive C layer, the 1 st retardation layer 141 is a positive C layer and the 2 nd retardation layer 142 is a λ/4 layer, or the 1 st retardation layer 141 is a λ/4 layer and the 2 nd retardation layer 142 is a positive C layer. When the retardation plate includes λ/2 layers, the 1 st retardation layer 141 is a λ/2 layer, and the 2 nd retardation layer 142 is a λ/4 layer. The thickness of the retardation plate 140 is, for example, 0.1 to 50 μm, preferably 0.5 to 30 μm, and more preferably 1 to 10 μm.

The 1 st retardation layer 141 and the 2 nd retardation layer 142 may be formed of a resin film exemplified as a material of the above thermoplastic resin film, or may be formed of a layer containing a cured product of a polymerizable liquid crystal compound. The 1 st retardation layer 141 and the 2 nd retardation layer 142 may further include an alignment film and a substrate film.

When the 1 st retardation layer 141 and the 2 nd retardation layer 142 are formed of a layer containing a cured product of a polymerizable liquid crystal compound, they can be formed by applying a composition containing a polymerizable liquid crystal compound to a substrate film and curing the composition. An alignment film may 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. When the 1 st retardation layer 141 and the 2 nd retardation layer 142 are formed of a layer containing a cured product of a polymerizable liquid crystal compound, they may be incorporated in a laminate in the form of having an alignment film and a substrate film.

The polarizing plate in which the linear polarizing plate and the phase difference plate 140 are arranged so that the absorption axis of the linear polarizing plate and the slow axis of the phase difference plate 140 form a predetermined angle has an antireflection function, i.e., functions as a circular polarizing plate. When the phase difference plate 140 includes the λ/4 layer, the angle of the absorption axis of the linear polarizer with the slow axis of the λ/4 layer may be 45 ° ± 10 °. The 1 st retardation layer 141 and the 2 nd retardation layer 142 may have positive wavelength dispersibility or may have reverse wavelength dispersibility. The lambda/4 layer preferably has reverse wavelength dispersion. The linearly polarizing plate and the phase difference plate 140 may be bonded to each other with an adhesive or a bonding agent.

[ interlayer lamination layer ]

The interlayer bonding layer 143 is disposed between the 1 st retardation layer 141 and the 2 nd retardation layer 142, and has a function of bonding the 1 st retardation layer 141 and the 2 nd retardation layer 142. The interlayer adhesive layer 143 may be made of an adhesive or bonding agent. The interlayer adhesive layer 143 is preferably an adhesive layer.

The elastic modulus [ MPa ] of the interlayer adhesive layer 143 may be, for example, 100MPa to 1 ten thousand MPa, and preferably 500MPa to 5000MPa. When the interlayer adhesive layer 143 is an adhesive layer, the compressive elastic modulus [ MPa ] of the interlayer adhesive layer 143 at room temperature may be, for example, 100MPa to 1 ten thousand MPa. The elastic modulus [ MPa ] of the interlayer bonding layer 143 can be adjusted by, for example, selecting a material for forming the interlayer bonding layer 143.

The thickness of the interlayer bonding layer 143 is not particularly limited, and when a pressure-sensitive adhesive layer is used as the interlayer bonding layer 143, it is preferably 1 μm or more, and may be 5 μm or more, usually 50 μm or less, and may be 25 μm or less. When an adhesive layer is used as the interlayer adhesive layer 143, the thickness of the interlayer adhesive layer 143 is preferably 0.1 μm or more, and may be 0.5 μm or more, preferably 10 μm or less, and may be 5 μm or less.

The adhesive used for the interlayer bonding layer 143 may be the adhesive composition described above, or may be another adhesive, for example, a (meth) acrylic adhesive, a styrene adhesive, a silicone adhesive, a rubber adhesive, a polyurethane adhesive, a polyester adhesive, an epoxy copolymer adhesive, or the like, which is different from the material of the adhesive layer.

The adhesive used for the interlayer adhesive layer 143 may be formed by combining 1 or 2 or more kinds of water-based adhesives, active energy ray-curable adhesives, and the like, for example. Examples of the aqueous adhesive include a polyvinyl alcohol resin aqueous solution and an aqueous two-pack polyurethane 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 photocurable epoxy-based monomers, photocurable acrylic-based monomers, and photocurable urethane-based monomers, and oligomers derived from these monomers. Examples of the photopolymerization initiator include compounds containing active species that generate neutral radicals, anionic radicals, and cationic radicals by irradiation with active energy rays such as ultraviolet rays.

[ touch sensor Panel ]

The touch sensor panel is not limited to any 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. Since the cost is low, a touch sensor panel of a resistive film type or a capacitive coupling type is preferably used. The touch sensor panel may be disposed on a side opposite to the viewing side of the laminate.

One 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 substrate, and a touch position detection circuit. In an image display device provided with a resistive touch sensor panel, when a front surface of a front panel is touched, opposing resistive films are short-circuited to allow a current to flow through the resistive films. The touch position detection circuit detects a change in voltage 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, when the front surface of the front panel is touched, the transparent electrode is grounded at the touched point via the capacitance of a human body. The touch position detection circuit detects the grounding of the transparent electrode, thereby detecting the touched position.

[ adhesive layer ]

The laminate may further include a bonding layer for bonding the linear polarizer and the phase difference plate, and for bonding the phase difference plate and the 2 nd optical member. The attachment layer may be formed of an adhesive or bonding agent. The adhesive and the pressure-sensitive adhesive exemplified in the above interlayer lamination layer can be used.

[ image display element ]

Examples of the image display element include a liquid crystal cell, an organic electroluminescence (organic EL) display element, an inorganic electroluminescence (inorganic EL) display element, a plasma display element, and a field emission display element.

[ method for producing laminate ]

The method for producing the laminate may include the following steps (a) to (g), for example. A method for manufacturing a laminate will be described with reference to fig. 2.

(a) Step of forming protective layer 131 on base film 109

(b) Process for producing linearly polarizing plate 130 by forming polarizer 132 on protective layer 131

(c) Process for providing overcoat 133 on polarizer 132

(d) A step of preparing a retardation plate 140 comprising a 1 st retardation layer 141, an interlayer adhesive layer 143, and a 2 nd retardation layer 142, and a touch sensor panel 152 having a base film 151

(e) Bonding the laminate of the retardation plate 140, the touch sensor panel 152 and the base film 151 to the overcoat layer 133 via the bonding layer 160 with the retardation plate 140 side as a bonding surface

(f) Step of peeling off the base film 109 in contact with the protective layer 131

(g) A step of bonding the front panel 111 to the protective layer 131 via the 1 st adhesive layer 120, and then peeling off the base film 151 in contact with the touch sensor panel 152

The method for manufacturing a laminate may include a step of forming an alignment film on the protective layer 131 between the steps (a) and (b). The lamination can be performed using a known laminator, roller, unit bonder, or the like. The bonding surface may be subjected to surface treatment such as corona treatment or plasma treatment.

< image display device >

An image display device of the present invention includes the laminate. The image display device is not particularly limited, and examples thereof include an organic EL display device, an inorganic EL display device, a liquid crystal display device, an electroluminescence display device, and the like. The image display device may have a touch panel function. The laminate is suitable for an image display device having flexibility such as bending or folding. In the case where the laminate has a front panel in the image display device, the laminate is disposed on the viewing side of the image display device with the front panel facing outward (the side opposite to the image display element side, i.e., the viewing side).

The image display device of the present invention can be used as a portable device such as a smart phone or a tablet, a television, a digital photo frame, an electronic signboard, a detector, an instrument, an office device, a medical instrument, a computer device, or the like. The image display device of the present invention has excellent flexibility, and is therefore suitable for flexible displays and the like.

Examples

The present invention will be described in more detail below with reference to examples. In the examples, "%" and "part(s)" are% by mass and part(s) by mass unless otherwise specified.

[ measurement of thickness ]

The thickness of each layer forming the laminate was measured in the following manner. The laminate was cut with a laser knife, 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 forming the flexible laminate was measured from the obtained observation image.

[ measurement of elastic modulus ]

The types of elastic modulus and the measurement objects for measuring the elastic modulus are shown below.

Storage elastic modulus: adhesive layer

Modulus of compression elasticity: coating layer (hard coating, adhesive layer)

Tensile modulus of elasticity: resin film

[ measurement of storage elastic modulus at ordinary temperature and-20 ℃ ]

The adhesive layer was laminated to a thickness of 150 μm to prepare a sample for measurement. The sample for measurement was placed in a rheometer (Anton Parr, MCR-301), and the storage elastic modulus was measured under conditions of a temperature of 25 ℃ and a relative humidity of 50% (or a temperature of-20 ℃), a stress of 1%, and a frequency of 1 Hz.

[ measurement of compression elastic modulus at Normal temperature ]

The modulus of elasticity under compression was measured using a nanoindenter (HM-500, manufactured by FISCHER INSTRUMTS) under conditions of a temperature of 25 ℃ and a relative humidity of 50% and a pressure of 1 mN. The indenter used a Berkovich (Berkovich) triangular hammer indenter.

[ measurement of tensile modulus at Normal temperature and-20 ℃ C ]

The tensile modulus was measured at a temperature of 25 ℃ and a relative humidity of 50% (or at a temperature of-20 ℃) using a tensile tester (AG-1S, manufactured by Shimadzu corporation). When the resin film to be measured has a retardation in the plane, the tensile modulus in the slow axis direction is measured.

[ rigidity (a) ]

The product of the measured thickness [ μm ] of the 1 st pressure-sensitive adhesive layer and the storage elastic modulus [ MPa ] at ordinary temperature was obtained.

[ rigidity (b) ]

The product of the measured thickness [ μm ] of the protective layer and the tensile elastic modulus [ MPa ] at ordinary temperature when the protective layer is a resin film or the compressive elastic modulus [ MPa ] at ordinary temperature when the protective layer is an inorganic layer or an organic layer (when it is a coating layer) is obtained.

[ rigidity (c) ]

The product of the measured thickness [ μm ] of the interlayer lamination layer and the storage elastic modulus [ MPa ] at the time when the interlayer lamination layer is an adhesive layer or the compression elastic modulus [ MPa ] at the time when the interlayer lamination layer is an adhesive layer is obtained.

[ rigidity (a') ]

The product of the measured thickness [ μm ] of the 1 st adhesive layer and the storage elastic modulus [ MPa ] at a temperature of-20 ℃ was determined.

[ rigidity (b') ]

The product of the measured thickness [ μm ] of the protective layer and the tensile elastic modulus [ MPa ] at room temperature when the protective layer is a resin film or the compressive elastic modulus [ MPa ] at room temperature when the protective layer is an inorganic layer or an organic layer (when the protective layer is a coating layer) is obtained.

[ rigidity (c') ]

The product of the measured thickness [ μm ] of the interlayer lamination layer and the storage elastic modulus [ MPa ] at a temperature of-20 ℃ when the interlayer lamination layer is an adhesive layer or the compression elastic modulus [ MPa ] at a temperature when the interlayer lamination layer is an adhesive layer is obtained.

[ repeated bending durability test ]

An evaluation test for confirming the durability against bending was carried out at a temperature of 25 ℃ or-20 ℃ using a bending evaluation apparatus (STS-VRT-500 manufactured by Science Town). Fig. 3 is a diagram schematically showing the method of the evaluation test. As shown in fig. 3, two tables 501 and 502, which are movable, are disposed in a gap C1, and a laminate 500 is fixedly disposed such that the center in the width direction is located at the center of the gap C ((a) in fig. 3). At this time, the laminate 500 is disposed so that the front panel (1 st optical member) side is upward. The region of the laminate 500 corresponding to the gap C of the mounting table is rotated upward by 90 degrees about the positions P1 and P2 as the center of the rotation axis, and the interval C2 between the facing front panels is set to 2.0mm in the test at a temperature of 25 ℃ and 3.0mm in the test at a temperature of-20 ℃ (fig. 3 (b)). Then, 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. The number of times of applying the bending force is counted, whether or not the crack or peeling occurs in the region of the phase difference plate of the laminated body 500 corresponding to the gap C between the mounting tables 501 and 502 is checked, the application of the bending force is stopped at the time when the crack or peeling occurs in the phase difference plate, and the number of times of applying the bending force when the crack or peeling occurs is recorded. The moving speed of the mounting tables 501 and 502 and the application speed of the bending force are the same in the evaluation test of any laminate.

[ static bending durability test ]

The method of the static bending durability test (mandrel bending test) is shown in fig. 4. First, the laminate 100 was cut into a test piece of 1cm × 10 cm. The test piece was placed on a test piece 503 so that the front plate 10 side of the laminate 100 was upward, and an iron rod 504 having a diameter of 5mm was placed thereon (fig. 4 (a)). The front panel 110 is folded and fixed by hand so as to be on the inside (fig. 4 (B)). The test was carried out under a normal temperature environment.

The static bending durability was evaluated as follows based on the period in which no crack was generated in the retardation plate 140.

A: no cracks were generated at the time of 30 days.

B: cracks were generated at the time of the lapse of 30 days.

C: cracks were generated at the time of 20 days.

D: cracks were generated at the time of 10 days.

[ acrylic pressure-sensitive adhesive layer 1]

A mixed solution of 81.8 parts of acetone, 98.8 parts of butyl acrylate, 0.2 part of acrylic acid and 1.0 part of 2-hydroxyethyl acrylate was charged into a reactor equipped with a cooling tube, a nitrogen inlet tube, a thermometer and a stirrer, and the atmosphere in the apparatus was replaced with nitrogen gas to remove oxygen and raise the internal temperature to 55 ℃. Then, the entire amount of a solution prepared by dissolving 0.14 parts of azobisisobutyronitrile (polymerization initiator) in 10 parts of acetone was added. After 1 hour of the addition of the polymerization initiator, acetone was continuously added to the reactor at an addition rate of 17.3 parts/hr so that the concentration of the acrylic resin 1 excluding the monomer was 35%, and the reactor was kept at an internal temperature of 54 to 56 ℃ for 12 hours, and finally ethyl acetate was added to adjust the concentration of the acrylic resin to 20%. Thereby obtaining an acrylic resin 1 solution.

100 parts (non-volatile amount) of the acrylic resin 1 solution, 0.3 part of Coronate L and 0.5 part of KBM-403 were mixed. Ethyl acetate was added so that the solid content concentration became 10%, to obtain a pressure-sensitive adhesive composition. The obtained adhesive composition was applied by an applicator to a release-treated surface of a polyethylene terephthalate film (thickness: 38 μm) which had been subjected to release treatment so that the dried thickness was 25 μm. The coating layer was dried at 100 ℃ for 1 minute to obtain a film having the adhesive layer 1. Then, another polyethylene terephthalate film (thickness 38 μm) subjected to a mold release treatment was attached to the adhesive layer. Then, the mixture was aged at 23 ℃ and a relative humidity of 50% RH for 7 days to obtain an acrylic pressure-sensitive adhesive layer 1.

[ acrylic pressure-sensitive adhesive layer 2]

An acrylic resin 2 solution was obtained in the same manner as the method for producing the acrylic resin 1 solution, except that the monomer composition was changed to 76 parts of butyl acrylate, 22 parts of methyl acrylate, and 2.0 parts of acrylic acid.

100 parts (non-volatile matter content) of the acrylic resin 2 solution, 1.0 part of Coronate L, and 0.5 part of KBM-403 were mixed. Ethyl acetate was added so that the solid content concentration became 10%, to obtain a pressure-sensitive adhesive composition. From the obtained pressure-sensitive adhesive composition, an acrylic pressure-sensitive adhesive layer 2 having a thickness of 7 μm was obtained in the same manner as in the production of the acrylic pressure-sensitive adhesive layer 1.

[ acrylic pressure-sensitive adhesive layer 3]

An acrylic resin 3 solution was obtained in the same manner as the production method of the acrylic resin 1 solution, except that the monomer composition was changed to 68.0 parts of butyl acrylate, 27 parts of methyl methacrylate, 4.0 parts of acrylic acid, and 1.0 part of 2-hydroxyethyl acrylate.

100 parts (non-volatile matter content) of the acrylic resin 3 solution, 3.0 parts of Coronate L, and 0.5 part of KBM-403 were mixed. Ethyl acetate was added so that the solid content concentration was 10%, to obtain a pressure-sensitive adhesive composition. From the obtained pressure-sensitive adhesive composition, an acrylic pressure-sensitive adhesive layer 3 having a thickness of 25 μm was obtained in the same manner as in the production of the acrylic pressure-sensitive adhesive layer 1.

[ acrylic pressure-sensitive adhesive layer 4]

An acrylic resin 4 solution was obtained in the same manner as the production method of the acrylic resin 1 solution, except that the monomer composition was changed to 68.0 parts of butyl acrylate, 29 parts of methyl methacrylate, 2.0 parts of acrylic acid, and 1.0 part of 2-hydroxyethyl acrylate.

100 parts (non-volatile amount) of the acrylic resin 4 solution, 3.0 parts of Coronate L and 0.5 part of KBM-403 were mixed. Ethyl acetate was added so that the solid content concentration became 10%, to obtain a pressure-sensitive adhesive composition. From the obtained pressure-sensitive adhesive composition, an acrylic pressure-sensitive adhesive layer 4 having a thickness of 5 μm was obtained in the same manner as in the production of the acrylic pressure-sensitive adhesive layer 1.

[ acrylic pressure-sensitive adhesive layer 5]

100 parts (non-volatile amount) of the acrylic resin 1 solution, 0.25 part of Coronate L and 0.5 part of KBM-403 were mixed. Ethyl acetate was added so that the solid content concentration became 10%, to obtain a pressure-sensitive adhesive composition. From the obtained pressure-sensitive adhesive composition, an acrylic pressure-sensitive adhesive layer 5 having a thickness of 25 μm was obtained in the same manner as in the production of the acrylic pressure-sensitive adhesive layer 1.

[ acrylic pressure-sensitive adhesive layer 6]

100 parts (non-volatile amount) of the acrylic resin 1 solution, 0.15 part of Coronate L and 0.5 part of KBM-403 were mixed. Ethyl acetate was added so that the solid content concentration was 10%, to obtain a pressure-sensitive adhesive composition. From the obtained pressure-sensitive adhesive composition, an acrylic pressure-sensitive adhesive layer 6 having a thickness of 25 μm was obtained in the same manner as in the production of the acrylic pressure-sensitive adhesive layer 1.

[ example 1]

A composition for forming a hard coat layer was prepared by mixing 2.8 parts of an 18-functional dendritic acrylate having an acrylic group (Miramer SP1106, miwon), 6.6 parts of a 6-functional urethane acrylate having an acrylic group (Miramer PU-620D, miwon), 0.5 part of a photopolymerization initiator (Irgacure-184, BASF corporation), 0.1 part of a leveling agent (BYK-3530, BYK corporation) and 90 parts of Methyl Ethyl Ketone (MEK).

A composition for forming a hard coat layer is applied to a substrate film comprising a polyethylene terephthalate film. The coating film was dried in an 80 ℃ oven for 3 minutes. The exposure dose is 500mJ/cm ² (365 nm reference)) The coating film was irradiated with ultraviolet rays to form a hard coat layer (thickness: 2 μm, compression modulus of elasticity at 25 ℃ 2963 MPa).

The composition for forming an alignment film is coated on the hard coat layer. After the coating film was dried, polarized UV was irradiated to form an alignment film. A composition containing a polymerizable liquid crystal compound and a dichroic dye is applied to an alignment film. The polymerizable liquid crystal compound was aligned and cured to form a polarizer (thickness: 2 μm). The composition for forming a cover layer is coated on a polarizer. The coating film was irradiated with ultraviolet rays to form an overcoat layer (thickness: 2 μm).

A retardation plate was prepared by bonding a.lambda./4 layer (thickness: 2 μm) and a positive C layer (thickness: 3 μm) with an adhesive layer (thickness: 2 μm, compression modulus of elasticity 2426MPa at 25 ℃ C.) interposed therebetween. The lambda/4 plate and the positive C layer are each composed of a layer in which a polymerizable liquid crystal compound is cured. The adhesive layer was a layer formed of an ultraviolet-curable adhesive which was a composition comprising 50 parts of 3, 4-epoxycyclohexylcarboxylic acid-3 ',4' -epoxycyclohexylmethyl ester (CEL 2021P, daicel Co., ltd.), 50 parts of 3-ethyl-3 { [ (3-ethyloxetan-3-yl) methoxy ] methyl } oxetane (OXT-221, toyo chemical Co., ltd.), 2.25 parts of a cationic polymerization initiator (CPI-100, san-Apro Co., ltd.), and 2 parts of 1, 4-diethoxynaphthalene.

The overcoat and the λ/4 layer were laminated via an acrylic adhesive layer 4 (thickness 5 μm). The retardation plate is laminated such that the angle formed by the absorption axis of the polarizer and the slow axis of the λ/4 layer is 45 °. Thus, a circularly polarizing plate with a substrate film comprising a substrate film, a hard coat layer, a polarizer, an overcoat layer, an acrylic pressure-sensitive adhesive layer and a retardation plate was produced.

A front panel was prepared in which a hard coat layer (10 μm) was formed on one surface of a polyimide resin film (40 μm in thickness). The base film was peeled from the circularly polarizing plate with the base film, and the hard coat layer (protective layer) was exposed. The hard coat layer (protective layer) of the circularly polarizing plate and the polyimide resin film of the front panel were laminated via an acrylic pressure-sensitive adhesive layer 1 (thickness 25 μm, storage elastic modulus at 25 ℃ C. Of 0.047MPa, storage elastic modulus at-20 ℃ C. Of 0.18 MPa).

A substitute for an organic EL panel was produced by laminating 2 sheets of polyimide resin films (38 μm thick and 50 μm thick) with an acrylic pressure-sensitive adhesive layer (25 μm thick). The positive C layer and a substitute for the organic EL panel were laminated via an acrylic pressure-sensitive adhesive layer 1 (thickness 25 μm). Thus, a laminate comprising a front panel, the 1 st adhesive layer, a circularly polarizing plate, an acrylic adhesive layer, and a substitute for an organic EL panel was produced.

The obtained laminate was subjected to repeated bending durability tests and static bending durability tests. The results are shown in Table 1.

[ example 2]

A laminate was produced in the same manner as in example 1, except that a triacetyl cellulose (TAC) film (having a thickness of 25 μm and a tensile elastic modulus at 23 ℃ of 3282 MPa) was used in place of the substrate and the hard coat layer. The circularly polarizing plate included in the laminate of example 2 was composed of TAC, a polarizer, an overcoat layer, an adhesive layer, and a retardation plate. The results are shown in Table 1.

[ example 3]

A laminate was produced in the same manner as in example 1 except that the 1 st adhesive layer for laminating the front panel and the circularly polarizing plate used an acrylic adhesive layer 2 (thickness 7 μm) having a storage elastic modulus at 25 ℃ of 0.25MPa and a storage elastic modulus at-20 ℃ of 1.3 MPa. The results are shown in Table 1.

[ example 4]

A laminate was produced in the same manner as in example 1 except that a λ/4 plate (2 μm) and a positive C layer (3 μm) were bonded to each other with an acrylic pressure-sensitive adhesive layer 3 (thickness 25 μm, storage elastic modulus at 25 ℃ of 1.207MPa, and storage elastic modulus at-20 ℃ of 3.1 MPa). The results are shown in Table 1.

[ example 5]

A laminate was produced in the same manner as in example 2 except that the 1 st adhesive layer for laminating the front panel and the circularly polarizing plate used an acrylic adhesive layer 5 (thickness 25 μm) having a storage elastic modulus at 25 ℃ of 0.049MPa and a storage elastic modulus at-20 ℃ of 0.12 MPa. The results are shown in Table 1.

[ example 6]

A laminate was produced in the same manner as in example 2 except that the 1 st adhesive layer for laminating the front panel and the circularly polarizing plate was an acrylic adhesive layer 6 (thickness: 25 μm) having a storage elastic modulus at 25 ℃ of 0.032MPa and a storage elastic modulus at-20 ℃ of 0.09 MPa. The results are shown in Table 1.

Comparative example 1

A laminate was produced in the same manner as in example 1 except that the 1 st adhesive layer for laminating the front panel and the circularly polarizing plate used an acrylic adhesive layer 3 (thickness: 25 μm) having a storage elastic modulus at 25 ℃ of 1.207MPa and a storage elastic modulus at-20 ℃ of 3.1 MPa. The results are shown in Table 1.

Comparative example 2

A laminate was produced in the same manner as in example 1, except that a Triacetylcellulose (TAC) film (thickness 25 μm, tensile elastic modulus at 23 ℃ 3282 MPa) was used instead of the base film and the hard coat layer, and a λ/4 plate (thickness 2 μm) and a positive C layer (thickness 3 μm) were bonded to each other through an acrylic pressure-sensitive adhesive layer 4 (thickness 5 μm, storage elastic modulus at 25 ℃ 0.87MPa, and storage elastic modulus at-20 ℃ 8.3 MPa) as a retardation plate. The results are shown in Table 1.

[ Table 1]

[ Table 2]

Description of the symbols

100 laminates, 109 base material films, 110 1 st optical member, 111 front panel, 120 1 st adhesive layer, 130 linear polarizer, 131 protective layer, 132 polarizer, 140 retardation plate, 141 1 st retardation layer, 142 nd retardation layer, 2 nd retardation layer, 143 interlayer lamination layer, 150 nd optical member, 151 base material films, 152 touch sensor panel, 160 lamination layer, 500 laminates, 501, 502 mounting base, 503 test plate, 504 iron rod.

Claims

1. A laminate comprising a 1 st optical member, a 1 st adhesive layer, a linearly polarizing plate, a retardation plate, and a 2 nd optical member in this order,

the linear polarizing plate comprises a protective layer and a polarizer in this order from the 1 st optical member side,

the phase difference plate comprises a 1 st phase difference layer and a 2 nd phase difference layer in order from the 1 st optical component side,

the 1 st retardation layer and the 2 nd retardation layer are bonded by an interlayer bonding layer,

the following conditions a and B are satisfied,

condition a: the first pressure-sensitive adhesive layer 1 has a rigidity a of 3MPa μm or less at room temperature,

condition B: the ratio b/c of the rigidity b of the protective layer at room temperature to the rigidity c of the interlayer adhesive layer at room temperature is 1 ten thousand or less.

2. The laminate according to claim 1, wherein the following conditions A 'and B' are further satisfied,

condition A': the first pressure-sensitive adhesive layer has a rigidity a' of 10MPa μm or less at a temperature of-20 ℃,

under the condition B': the ratio b '/c' of the rigidity b 'of the protective layer at a temperature of-20 ℃ to the rigidity c' of the interlayer adhesive layer at a temperature of-20 ℃ is 1 thousand or less.

3. A laminate comprising a 1 st optical member, a 1 st adhesive layer, a linearly polarizing plate, a retardation plate, and a 2 nd optical member in this order,

the following conditions a 'and B' are satisfied,

the condition A': the first adhesive layer has a rigidity a' of 10 MPa-mum or less at a temperature of-20 ℃,

condition B': the ratio b '/c' of the rigidity b 'of the protective layer at a temperature of-20 ℃ to the rigidity c' of the interlayer adhesive layer at a temperature of-20 ℃ is 1 thousand or less.

4. The laminate according to any one of claims 1 to 3, wherein the following condition C is further satisfied,

condition C: the rigidity c of the interlayer adhesive layer at normal temperature is 10 MPa-mum or more.

5. The laminate according to any one of claims 1 to 4, wherein the 2 nd retardation layer has a layer comprising a cured product of a polymerizable liquid crystal compound.

6. The laminate according to any one of claims 1 to 5, wherein the interlayer lamination layer is an adhesive layer.

7. The laminate according to any one of claims 1 to 6, wherein the 1 st optical member is a front panel and the 2 nd optical member is a touch sensor panel.

8. An image display device comprising the laminate according to any one of claims 1 to 7.