CN117015728A

CN117015728A - Laminate body

Info

Publication number: CN117015728A
Application number: CN202280019217.XA
Authority: CN
Inventors: 吴大钊
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2021-06-02
Filing date: 2022-05-23
Publication date: 2023-11-07
Also published as: JP2022185419A; WO2022255155A1; KR20240015092A; TW202321036A

Abstract

The invention provides a laminate, which is laminated with a linear polarization layer, a 1 st adhesive layer, a liquid crystal coating layer and a 2 nd adhesive layer in sequence, and is not easy to generate cracks when repeatedly bending with the linear polarization layer side as the outer side. The laminate is provided with a linear polarization layer, a 1 st adhesive layer, a liquid crystal coating layer and a 2 nd adhesive layer which are laminated in this order, wherein when the storage modulus of the 1 st adhesive layer at 25 ℃ is G '1[ kPa ] and the storage modulus of the 2 nd adhesive layer at 25 ℃ is G'2[ kPa ], G '1 is not less than 1000kPa and G'2 is not less than 1000kPa are satisfied.

Description

Laminate body

Technical Field

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

Background

Patent document 1 discloses a laminate comprising, in order, a 1 st protective layer, a 1 st adhesive layer, an intermediate coating layer, and a 2 nd adhesive layer, and proposes that the ratio of the storage modulus at 25 ℃ to the thickness of the 1 st adhesive layer and the 2 nd adhesive layer be set within a certain range in order to suppress occurrence of cracks in the intermediate coating layer when bending is performed with the 1 st protective layer as the inner side.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2020-157577

Disclosure of Invention

Problems to be solved by the invention

The laminate described in patent document 1, which is bendable inside the viewing side, is used for a flexible display, which is bendable inside the viewing side surface. As a laminate used in a flexible display that can be bent with the viewing side surface as the outside, a laminate that can be bent with the viewing side surface as the outside is required.

The invention provides a laminated body in which a linear polarization layer, a 1 st adhesive layer, a liquid crystal coating layer and a 2 nd adhesive layer are laminated in order, and which is less likely to generate cracks when repeatedly bent with the linear polarization layer side as the outer side, and a display device provided with the laminated body.

Means for solving the problems

The present invention provides the following laminate and image display device.

[1] A laminate comprising a linear polarizing layer, a 1 st adhesive layer, a liquid crystal coating layer and a 2 nd adhesive layer laminated in this order,

the following condition (1) is satisfied when the storage modulus of the 1 st adhesive layer at a temperature of 25 ℃ is G '1[ kPa ], and the storage modulus of the 2 nd adhesive layer at a temperature of 25 ℃ is G'2[ kPa ].

(1) G '1 is more than or equal to 1000kPa and G'2 is more than or equal to 1000kPa

[2] The laminate according to item [1], wherein the linearly polarizing layer comprises a cured product of a composition containing a polymerizable liquid crystal compound and 1 or more azo pigments, and an alignment film.

[3] The laminate according to [1] or [2], wherein the liquid crystal coating layer is formed of 1 or more layers.

[4] The laminate according to any one of [1] to [3], wherein at least 1 protective layer selected from a thermoplastic resin film and a cured resin layer is provided on the side of the linearly polarizing layer opposite to the 1 st adhesive layer.

[5] The laminate according to [4], wherein the protective layer has a front panel on the side opposite to the linearly polarizing layer via a 3 rd adhesive layer.

[6] The laminate according to [5], wherein the front panel has a tensile elastic modulus of 4.0GPa or more at a temperature of 23 ℃.

[7] The laminate according to [5] or [6], wherein the storage modulus of the 3 rd adhesive layer at a temperature of 25℃is 50KPa or less.

[8] The laminate according to any one of [1] to [7], wherein an organic EL panel is provided on the side of the 2 nd adhesive layer opposite to the liquid crystal coating layer.

[9] The laminate according to any one of [1] to [8], wherein the organic EL panel has a tensile elastic modulus of 4.0GPa or more at a temperature of 23 ℃.

[10] An image display device comprising the laminate according to any one of [1] to [9 ].

Effects of the invention

According to the present invention, a laminate in which a linearly polarizing layer, a 1 st adhesive layer, a liquid crystal coating layer, and a 2 nd adhesive layer are laminated in this order is provided, and cracks are less likely to occur when the laminate is repeatedly bent with the linearly polarizing layer side as the outer side.

Drawings

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

Fig. 2 is a schematic cross-sectional view showing another example of the layer structure of the laminate of the present invention.

Fig. 3 is a schematic cross-sectional view showing still another example of the layer structure of the laminate of the present invention.

FIG. 4 is a schematic diagram illustrating a method of bending 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 shown in the drawings is not necessarily identical to the scale of the actual component, and is appropriately adjusted to facilitate understanding of the components.

< laminate >

In one embodiment of the present invention, a laminate is formed by laminating a linear polarizing layer, a 1 st adhesive layer, a liquid crystal coating layer, and a 2 nd adhesive layer in this order, wherein the following condition (1) is satisfied when the storage modulus of the 1 st adhesive layer at a temperature of 25 ℃ is G '1[ kPa ] and the storage modulus of the 2 nd adhesive layer at a temperature of 25 ℃ is G'2[ kPa ].

Fig. 1 is a schematic cross-sectional view of a laminate according to an embodiment of the present invention. The laminate 100 shown in fig. 1 is laminated with a linear polarization layer 10, a 1 st adhesive layer 11, a liquid crystal coating layer 12, and a 2 nd adhesive layer 13 in this order. The 1 st adhesive layer 11 and the 2 nd adhesive layer 13 are each disposed in contact with the liquid crystal coating layer 12. The linear polarization layer 10 and the 1 st adhesive layer 11 may be disposed so as to be in contact with each other. The liquid crystal coating layer 12 does not include a polarizing plate including a cured product of a polymerizable liquid crystal compound as one form of the linear polarizing layer 10. The laminate 100 may include other layers such as a protective layer, a front panel, a 3 rd adhesive layer, a bonding layer, an organic EL panel, and a touch sensor, in addition to the above layers.

The laminate 100 can be bent (hereinafter, also referred to as "out-folded") with respect to a bending axis with the linear polarization layer 10 side as an outer side. The term bendable means that the laminate can be bent without causing cracks in the liquid crystal coating layer and the polarizing plate layer. Bending includes a bending form that forms a curved surface at a bent portion. In the bent form, the bending radius of the inner surface after bending is not particularly limited. In addition, the bending includes a bending form in which the bending angle of the inner surface is greater than 0 ° and less than 180 °, and a folding form in which the bending radius of the inner surface is approximately zero or the bending angle of the inner surface is 0 °. The laminate of the present invention is capable of bending and is therefore suitable for flexible displays.

The bending radius of the laminate 100, which is less likely to cause cracking even when repeatedly bent in an external folding test described later, may be, for example, 4mm, and preferably 2mm. When the laminate 100 is repeatedly bent at a bending radius of 2mm in the external folding test, the number of times of bending in which the crack is initially generated is preferably 20 ten thousand times or more, more preferably 30 ten thousand times or more, still more preferably 40 ten thousand times or more, and particularly preferably 50 ten thousand times or more.

The thickness of the laminate 100 is not particularly limited, and is, for example, 30 μm or more and 4000 μm or less, preferably 2000 μm or less, and more preferably 1000 μm or less, because it varies depending on the function required for the laminate, the use of the laminate, and the like. In the present specification, the thickness of the laminate and each layer can be measured by the thickness measurement method described in examples described below.

The planar shape of the laminate 100 may be, for example, a square shape, preferably a square shape having long sides and short sides, and more preferably a rectangle. When the laminate 100 has a rectangular shape in the plane direction, the length of the long side may be, for example, 10mm to 1400mm, and preferably 600 mm. The length of the short side is, for example, 5mm to 800mm, preferably 500mm or less, and more preferably 300mm or less. Each layer constituting the laminate may be R-cut at the corners, cut at the ends, or perforated.

[ storage modulus of adhesive layer at 25 ℃ C ]

The laminate 100 satisfies the above condition (1). The present inventors have found that by disposing a liquid crystal coating layer between 2 relatively hard adhesive layers having a storage modulus of 1000kPa or more at 25 ℃, the liquid crystal coating layer can be folded out and repeatedly bent. The storage modulus at a temperature of 25℃can be measured by the method described in the column of examples described below.

The storage modulus G '1[ kPa ] of the 1 st adhesive layer 11 at a temperature of 25 ℃ and the storage modulus G'2[ kPa ] of the 2 nd adhesive layer 13 at a temperature of 25 ℃ are preferably 1100kPa or more, more preferably 1200ka or more, still more preferably 1300kPa or more, particularly preferably 1400kPa or more. The storage moduli of the 1 st adhesive layer 11 and the 2 nd adhesive layer 13 at the temperature of 23 ℃ may be the same as or different from each other.

The 1 st adhesive layer 11 and the 2 nd adhesive layer 13 are formed of an adhesive composition described later. The storage modulus G '1[ kpa ] of the 1 st adhesive layer 11 at a temperature of 25 ℃ and the storage modulus G'2[ kpa ] of the 2 nd adhesive layer 13 at a temperature of 25 ℃ can be adjusted by, for example, selecting the kind of the monomer constituting the (meth) acrylic polymer contained in the adhesive composition, adjusting the molecular weight of the (meth) acrylic polymer, adjusting the crosslinking density by the addition amount of the crosslinking agent, adjusting the thickness of the adhesive layer, a method of combining them, and the like. The binder having a desired storage modulus may also be selected from commercially available binders.

[ use of laminate ]

The laminate 100 can be used for an image display device or the like, for example. 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 electroluminescent display device. The image display device may have a touch panel function. The image display device may preferably be a flexible display. The laminate 100 can be disposed in an image display device such that the linearly polarizing layer 10 side is the observation side.

[ Linear polarization layer ]

Examples of the linear polarization layer 10 include a stretched film or a stretched layer having a dichroic dye adsorbed thereto, and a polarizing plate layer obtained by coating and curing a dichroic dye. The polarizing plate layer obtained by applying and curing the dichroic dye is preferable because the bending direction is not limited to a stretched film or a stretched layer to which the dye having absorption anisotropy is adsorbed.

As the dichroic dye, specifically, iodine and a dichroic organic dye can be used. Examples of the dichroic organic dye include azo dyes. The azo-based dye includes, for example, a dichroic direct dye containing a disazo compound such as c.i. direct RED 39, and a dichroic direct dye containing a compound such as trisazo or tetrazo.

(stretched film or stretched layer having a dichroic dye adsorbed thereto)

The stretched film having the dichroic dye adsorbed thereto can be generally produced by a process of uniaxially stretching a polyvinyl alcohol resin film, a process of adsorbing the dichroic dye by dyeing the polyvinyl alcohol resin film with the dichroic dye, a process of treating the polyvinyl alcohol resin film having the dichroic dye adsorbed thereto with an aqueous boric acid solution, and a process of washing with water after the treatment with the aqueous boric acid solution.

The thickness of the stretched film having the dichroic dye adsorbed thereto may be, for example, 2 μm or more and 40 μm or less, may be 5 μm or more, may be 20 μm or less, may be 15 μm or less, and may be 10 μm or less.

The polyvinyl alcohol resin is obtained by saponifying a polyvinyl acetate resin. As the polyvinyl acetate resin, a copolymer of vinyl acetate and other monomers copolymerizable therewith may be used 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 85 mol% or more and 100 mol% or less, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The polymerization degree of the polyvinyl alcohol resin is usually 1000 to 10000, preferably 1500 to 5000.

The stretched layer having the dichroic dye adsorbed thereto can be generally produced by the following steps: the method for producing a polarizing plate comprises a step of applying a coating liquid containing the polyvinyl alcohol resin onto a base film, a step of uniaxially stretching the obtained laminated film, a step of dyeing a polyvinyl alcohol resin layer of the uniaxially stretched laminated film with a dichroic dye to adsorb the dichroic dye to produce a polarizing plate layer, a step of treating the film adsorbed with the dichroic dye with an aqueous boric acid solution, and a step of washing with water after the treatment with the aqueous boric acid solution.

The base film may be peeled off from the stretched layer to which the dichroic dye is adsorbed, if necessary. The material and thickness of the base film may be the same as those of the thermoplastic resin film described later.

(polarizing plate layer obtained by coating and curing a dichroic dye)

Examples of the polarizing plate layer obtained by applying and curing a dichroic dye include a polarizing plate layer containing a cured product of a polymerizable liquid crystal compound, such as a layer obtained by applying and curing a composition containing a polymerizable liquid crystal compound and a dichroic dye to a base film. The substrate film may be provided with an alignment film on one surface. From the viewpoint of improving the bending property, the linearly polarizing layer 10 is preferably a layer including a cured product of a composition containing a polymerizable liquid crystal compound and 1 or more azo-based pigments, and an alignment film. The thickness of the alignment film may be, for example, 5nm or more and 1 μm or less.

The linear polarizing layer may be assembled together with the base film in a laminate, or may be assembled by peeling and removing the base film from a polarizing plate layer obtained by applying and curing a dichroic dye. The material and thickness of the base film may be the same as those of the thermoplastic resin film described later. The base film may have a hard coat layer (HC layer) formed on at least one surface as a protective layer described later.

The thickness of the polarizing plate layer obtained by applying and curing the dichroic dye is usually 10 μm or less, preferably 8 μm or less, and more preferably 5 μm or less.

Protective layer

The protective layer is disposed on one side or both sides of the linear polarization layer 10, and can have a function of protecting the surface of the linear polarization layer 10. In this specification, the linearly polarizing layer on which the protective layer is laminated is sometimes referred to as a linearly polarizing plate.

The protective layer 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 may be a cured resin layer of 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. In the case where the protective layer is an organic layer, the protective layer may be a protective layer called a hard coat layer (HC layer) or an overcoat layer (OC layer). The protective layer may be formed directly on the base film or directly on the linear polarizing layer. After forming the protective layer on the base film, a linearly polarizing layer may be formed.

When the protective layer is an organic layer, for example, the active energy ray-curable composition for forming a protective layer is applied to a base film, and the base film is cured by irradiation with active energy, whereby a protective layer can be produced. The substrate film may be as described above. The protective layer may be assembled to the laminate in a state where the base film is peeled off. Examples of a method for applying the composition for forming a protective layer include spin coating. In the case where the protective layer is an inorganic layer, the protective layer can be formed by, for example, sputtering, vapor deposition, or the like. In the case where the protective layer is an organic layer or an inorganic layer, the thickness of the protective layer may be, for example, 0.1 μm or more and 10 μm or less, and preferably 5 μm or less.

As the protective layer, 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; polyimide resin; polyolefin resins such as polyethylene, polypropylene and ethylene-propylene copolymers; a cyclic polyolefin resin having a ring system and a norbornene structure (also referred to as a norbornene-based resin); (meth) acrylic resins; a polyarylate resin; a polystyrene resin; polyvinyl alcohol resins, and mixtures thereof. In the case where the protective layers are laminated on both sides of the linear polarization layer 10, the two protective layers may be the same type or different types. From the viewpoint of thickness reduction, the thickness of the thermoplastic resin film is usually 300 μm or less, preferably 200 μm or less, more preferably 100 μm or less, still more preferably 50 μm or less, still more preferably 30 μm or less, and further usually 1 μm or more, for example, 5 μm or more or 20 μm or more.

When the protective layer is a thermoplastic resin film, the thermoplastic resin film may be bonded to the linear polarization layer 10 via a bonding layer described later. As the bonding layer for bonding the thermoplastic resin film to the linear polarization layer 10, an adhesive layer is preferable. Alternatively, a linearly polarizing layer may be formed on the protective layer. The laminate 100 preferably includes at least 1 protective layer selected from a thermoplastic resin film and a cured resin layer on the side of the linearly polarizing layer 10 opposite to the 1 st adhesive layer 11.

[ 1 st adhesive layer and 2 nd adhesive layer ]

The 1 st adhesive layer 11 may be a layer interposed between the linearly polarizing layer 10 and the liquid crystal coating layer 12 and bonding them. The 2 nd adhesive layer 13 may be a layer formed by bonding, for example, a touch sensor panel, an organic EL panel, or the like to the liquid crystal coating layer 12 side of the laminate 100. Hereinafter, the 1 st adhesive layer 11 and the 2 nd adhesive layer 13 are collectively referred to as "adhesive layers" in some cases.

The adhesive layer may be, for example, a layer made of an adhesive or a layer obtained by subjecting the layer to a certain treatment. Adhesives are also known as pressure sensitive adhesives. In the present specification, the term "adhesive" refers to an adhesive other than an adhesive (pressure-sensitive adhesive), and is clearly distinguished from an adhesive. The adhesive layer may be 1 layer or 2 or more layers, and preferably 1 layer. The adhesive layer may be formed of an adhesive composition. The types of the adhesives used in the 1 st adhesive layer 11 and the 2 nd adhesive layer 13 may be the same or different from each other.

The adhesive layer may be composed of an adhesive composition containing a resin such as a (meth) acrylic, rubber, urethane, ester, silicone, polyvinyl ether, or the like as a main component. Among them, an adhesive composition based on a (meth) acrylic resin excellent in transparency, weather resistance, heat resistance and the like is preferable. The adhesive composition may be an active energy ray-curable type or a thermosetting type.

As the (meth) acrylic resin (base polymer) used in the adhesive composition, for example, a polymer or copolymer containing 1 or 2 or more monomers among (meth) acrylic esters such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate is suitably used. The polar monomer is preferably copolymerized with the base polymer. 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 base polymer, but usually also contains a crosslinking agent. As the crosslinking agent, there may be exemplified: a crosslinking agent which is a metal ion having a valence of 2 or more and which forms a metal carboxylate with a carboxyl group; a crosslinking agent which is a polyamine compound and forms an amide bond with a carboxyl group; a crosslinking agent which is a polyepoxide, a polyhydric alcohol, and forms an ester bond with a carboxyl group; a crosslinking agent which is a polyisocyanate compound and forms an amide bond with a carboxyl group. Among them, polyisocyanate compounds are preferable.

The active energy ray-curable adhesive composition is an adhesive composition which is cured by irradiation with active energy rays such as ultraviolet rays and electron beams, has adhesion to an adherend such as a film even before irradiation with active energy rays, and has a property of being cured by irradiation with active energy rays to adjust adhesion force. The active energy ray-curable adhesive composition is preferably an ultraviolet ray-curable adhesive composition. The active energy ray-curable adhesive composition contains an active energy ray-polymerizable compound in addition to the base polymer and the crosslinking agent. In addition, a photopolymerization initiator, a photosensitizer, and the like may be contained as necessary.

The adhesive composition may contain fine particles for imparting light scattering properties, beads (resin beads, glass beads, etc.), glass fibers, resins other than the base polymer, tackifiers, fillers (metal powder, other inorganic powder, etc.), antioxidants, ultraviolet absorbers, dyes, pigments, colorants, defoamers, anticorrosive agents, antistatic agents, photopolymerization initiators, and other additives.

The adhesive layer may be formed by coating the organic solvent diluent of the above adhesive composition on a substrate and drying it. When the active energy ray-curable adhesive composition is used, a cured product having a desired degree of cure can be produced by irradiating the formed adhesive layer with active energy rays.

The 1 st adhesive layer 11 and the 2 nd adhesive layer 13 may be selected from commercially available products so as to satisfy the above condition (1).

The thickness of the adhesive layer is, for example, preferably 1 μm or more and 100 μm or less, more preferably 50 μm or less, and may be 20 μm or more. The thicknesses of the 1 st adhesive layer 11 and the 2 nd adhesive layer 13 may be the same as or different from each other.

[ liquid Crystal coating ]

The liquid crystal coating layer 12 is interposed between the 1 st adhesive layer 11 and the 2 nd adhesive layer 13, and is laminated in contact with the 1 st adhesive layer 11 and the 2 nd adhesive layer 13. The liquid crystal coating 12 may be a cured layer of a polymerizable liquid crystal compound. The liquid crystal coating layer is composed of 1 layer or multiple layers. In the case where the liquid crystal coating layer is composed of a plurality of layers, the layers may be laminated together via a bonding layer described later, and preferably laminated via an adhesive layer described later.

The liquid crystal coating 12 may be a cured layer of a polymerizable liquid crystal compound. The cured layer of the polymerizable liquid crystal compound can be formed by applying a composition for forming a retardation layer containing the polymerizable liquid crystal compound to a base film and curing the composition. Examples of the coating method include a coating method and a printing method. Examples of the coating method include bar coating, blade coating, die coating, direct gravure coating, reverse gravure coating, roll coating, CAP coating, spin coating, spray coating, screen coating, slit coating, and dip coating. Examples of the printing method include offset printing, gravure printing, screen printing, and inkjet printing.

The cured layer of the polymerizable liquid crystal compound may be a retardation layer. The retardation layer may be composed of 1 layer or 2 layers or more. 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. In the case where the liquid crystal coating layer 12 includes only 1 cured layer of a polymerizable liquid crystal compound, the retardation layer is preferably a λ/4 plate. In the case where the liquid crystal coating layer 12 includes 2 cured layers of a polymerizable liquid crystal compound, the retardation layer may be a retardation layer laminate including a 1 st liquid crystal cured retardation layer and a 2 nd liquid crystal cured retardation layer. The 1 st liquid crystal cured retardation layer and the 2 nd liquid crystal cured retardation layer may be laminated via a later-described adhesive layer, preferably via an adhesive layer. As the combination of the 1 st liquid crystal cured retardation layer and the 2 nd liquid crystal cured retardation layer, a combination in which the 1 st liquid crystal cured retardation layer is a λ/4 plate and the 2 nd liquid crystal cured retardation layer is a λ/2 plate, and a combination in which the 1 st liquid crystal cured retardation layer is a λ/4 plate and the 2 nd liquid crystal cured retardation layer is a positive C plate are preferable. In this specification, a linear polarizing plate in which a retardation layer is laminated may be referred to as a circular polarizing plate.

The thickness of the retardation layer is, for example, 0.1 μm or more and 10 μm or less, preferably 8 μm or less, and more preferably 6 μm or less.

An alignment layer may be formed between the base film and the cured layer of the polymerizable liquid crystal compound. The material and thickness of the base film may be the same as those of the thermoplastic resin film described above. The retardation layer obtained by curing the polymerizable liquid crystal compound may be assembled together with any one or both of the alignment layer and the base film in the laminate 100. The thickness of the alignment layer may be, for example, 5nm or more and 1 μm or less.

The thickness of the liquid crystal coating 12 may be, for example, 0.1 μm or more and 10 μm or less, preferably 8 μm or less, and more preferably 6 μm or less.

[ front panel ]

The front panel forms the outermost surface of the image display device on the viewing side, and may have a function of protecting the front surface (screen) of the image display device. The front panel may be a front panel called a window film. The front panel is not limited in material and thickness as long as it is a plate-like body capable of transmitting 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.), a glass plate-like body (e.g., a glass plate, a glass film, etc.), and a touch sensor panel described later. In the case where the laminate 100 has a front panel, the front panel may be disposed on the viewing side of the laminate 100. The laminate 100 may include a front panel on the outermost surface of the linearly polarizing layer 10 opposite to the 1 st adhesive layer 11 through a 3 rd adhesive layer described later. The laminate 100 having the front panel may be disposed on the image display device such that the front panel forms the outermost surface of the image display device.

The thickness of the front panel may be, for example, 30 μm or more and 500 μm or less, preferably 200 μm or less, and more preferably 100 μm or less.

In the case where the front panel is a resin plate-like body, the resin plate-like body is not limited as long as it can transmit light. Examples of the resin constituting the resin plate-like body such as a resin film include films formed of a polymer such as triacetylcellulose, acetylcellulose butyrate, ethylene-vinyl acetate copolymer, propionylcellulose, butyrylcellulose, 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, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, and polyamideimide. These polymers may be used singly or in combination of 2 or more. From the viewpoint of improving strength and transparency, a resin film formed of a polymer such as polyimide, polyamide, or polyamideimide is preferable.

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

In the case where the front panel is a glass plate, the glass plate is preferably reinforced glass for display. The thickness of the glass plate may be, for example, 50 μm or more and 1000 μm or less. By using a glass plate, a front panel having excellent mechanical strength and surface hardness can be constituted.

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

The tensile elastic modulus of the front panel at a temperature of 23 ℃ is preferably 4.0GPa or more, more preferably 5.0GPa or more, and even more preferably 6.0GPa or more, from the viewpoint of easy construction of the laminate 100 having excellent bendability. The tensile elastic modulus of the front panel at a temperature of 23 ℃ is preferably 20GPa or less, more preferably 15GPa or less, from the viewpoint of easy formation of a laminate having excellent bendability. The tensile modulus at a temperature of 23℃can be measured by the test method described in the column of the examples below. The laminate 100 can be repeatedly bent by folding out even when it has a front panel having a tensile elastic modulus of 6.0GPa at a temperature of 23 ℃.

The base film constituting the front panel may be formed of, for example, a resin film, and preferably may be formed of a transparent resin film. Examples of the resin constituting the resin film include polyolefin such as polyethylene, polypropylene, norbornene polymer and cyclic olefin resin; polyvinyl alcohol; polyethylene terephthalate; a polymethacrylate; a polyacrylate; cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; a polycarbonate; polysulfone; polyether sulfone; polyether ketone; polyphenylene sulfide; polyphenylene ether; a polyamide; polyimide; polyamide imide and other plastics. Among them, cyclic olefin resins, cellulose esters and polyimides are preferable.

From the viewpoint of thinning the laminate 100, the thinner the resin film is, the more preferable, but if it is too thin, it tends to be difficult to secure impact resistance. The thickness of the resin film may be, for example, 10 μm or more and 200 μm or less, preferably 15 μm or more, and more preferably 20 μm or more.

The substrate film may have a hard coat layer, an antireflection layer, or an antistatic layer on at least one surface.

[ 3 rd adhesive layer ]

The 3 rd adhesive layer may have a function of joining the front panel to the laminate 100. The 3 rd adhesive layer may be formed of an adhesive. The adhesive constituting the 3 rd adhesive layer may be the same adhesive as exemplified for the adhesive composition constituting the adhesive layer, or may be other adhesives such as (meth) acrylic adhesives, styrene adhesives, silicone adhesives, rubber adhesives, urethane adhesives, polyester adhesives, epoxy copolymer adhesives, and the like. The storage modulus of the 3 rd adhesive layer at a temperature of 25℃is preferably 50kPa or less, more preferably 45kPa or less, and even more preferably 41kPa or less, from the viewpoint that cracking of the liquid crystal coating layer is less likely to occur during bending.

[ adhesive layer ]

The bonding layer is a layer made of an adhesive or an adhesive. The bonding layer may be, for example, a layer bonding the front panel and the touch sensor panel, a layer bonding the laminate and the touch sensor panel, a layer bonding the linearly polarizing layer and the protective layer, a layer bonding the 1 st liquid crystal cured retardation layer and the 2 nd liquid crystal cured retardation layer, or the like. The adhesive constituting the adhesive layer may be the same adhesive as exemplified for the adhesive composition constituting the adhesive layer, or may be other adhesives such as (meth) acrylic adhesives, styrene adhesives, silicone adhesives, rubber adhesives, urethane adhesives, polyester adhesives, epoxy copolymer adhesives, and the like. The laminate 100 may have 1 bonding layer or may have 2 or more bonding layers. When the laminate 100 includes a plurality of bonding layers, the plurality of bonding layers may be the same as or different from each other.

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

When the pressure-sensitive adhesive layer is used as the bonding layer, it is preferably 1 μm or more, but it may be 5 μm or more, usually 200 μm or less, and for example, it may be 150 μm or less or 100 μm or less. When the adhesive layer is used as the bonding layer, the thickness of the bonding layer is preferably 0.1 μm or more, may be 0.5 μm or more, preferably 10 μm or less, and may be 5 μm or less.

(organic EL panel)

The organic EL panel may be any known organic EL panel. The laminate 100 may include an organic EL panel on the side opposite to the liquid crystal coating layer 12 of the 2 nd adhesive layer 13. The tensile elastic modulus of the organic EL panel at a temperature of 23 ℃ is preferably 4.0GPa or more, more preferably 5.0GPa or more, and even more preferably 6.0GPa or more, from the viewpoint of easy formation of a laminate having excellent bendability. The tensile elastic modulus of the organic EL panel at a temperature of 23 ℃ is preferably 20GPa or less, more preferably 15GPa or less, from the viewpoint of easy formation of a laminate having excellent bendability. Even when the laminate 100 is provided with an organic EL panel having a tensile elastic modulus of 6.0GPa at a temperature of 23 ℃, the laminate can be repeatedly bent by folding out.

(touch sensor Panel)

The touch sensor panel is not limited as long as it is a sensor capable of detecting a touched position, and examples thereof include a resistive film type, a capacitive type, a photosensor type, an ultrasonic type, an electromagnetic induction coupling type, a surface elastic wave type, and the like. Among them, capacitive touch sensor panels are preferably used in terms of low cost, rapid reaction speed, and thin film. The touch sensor panel may include an adhesive layer, a separation layer, a protective layer, and the like between the transparent conductive layer and the substrate film supporting the transparent conductive layer. The adhesive layer may be an adhesive layer or an adhesive layer. Examples of the substrate film for supporting the transparent conductive layer include a substrate film having a transparent conductive layer formed on one surface by vapor deposition, a substrate film having a transparent conductive layer transferred via an adhesive layer, and the like.

An example of the capacitive touch sensor panel is composed of a base film, a transparent conductive layer for detecting a position provided on the surface of the base film, and a touch position inspection circuit. In an image display device provided with a laminate of touch sensor panels having a capacitance system, if the surface of a front panel is touched, a transparent conductive layer is grounded via the capacitance of a human body at the point where the touch is made. The touch position checking circuit checks the grounding of the transparent conductive layer and detects the touched position. By having a plurality of transparent conductive layers separated from each other, more detailed detection of the position can be performed.

The transparent conductive layer may be a transparent conductive layer containing a metal oxide such as ITO, or may be a metal layer containing a metal such as aluminum, copper, silver, gold, or an alloy thereof. The transparent electrode layer is formed by a coating method such as a sputtering method, a printing method, or a vapor deposition method. A photosensitive resist is formed on the transparent electrode layer, and then an electrode pattern layer is formed by photolithography. The photosensitive resist may be a negative type photosensitive resist or a positive type photosensitive resist, and may be left after patterning or may be removed. In the case of forming a film by a sputtering method, a mask having an electrode pattern shape may be disposed, and sputtering may be performed to form an electrode pattern layer.

The separation layer may be a layer formed over a substrate such as glass, and the transparent conductive layer formed over the separation layer may be separated from the substrate together with the separation layer. The separation layer is preferably an inorganic layer or an organic layer. As a material for forming the inorganic layer, for example, silicon oxide is given. As a material for forming the organic layer, for example, a (meth) acrylic resin composition, an epoxy resin composition, a polyimide resin composition, or the like can be used. The separation layer may be formed by coating by a known coating method, and curing by a method of thermal curing or UV curing or a combination thereof.

The protective layer may be provided to protect the conductive layer in contact with the transparent conductive layer. The protective layer contains at least one of an organic insulating film and an inorganic insulating film, and these films can be formed by a coating method such as spin coating, sputtering, vapor deposition, or the like.

The insulating layer may be formed of, for example, an inorganic insulating material such as silicon oxide or a transparent organic material such as an acrylic resin. The insulating layer can be formed by applying a known coating method, and then thermally curing, UV curing, thermal drying, vacuum drying, or the like.

Examples of the substrate film of the touch sensor panel include resin films of triacetylcellulose, polyethylene terephthalate, cycloolefin polymer, polyethylene naphthalate, polyolefin, polycycloolefin, polycarbonate, polyethersulfone, polyarylate, polyimide, polyamide, polystyrene, polynorbornene, and the like. Polyethylene terephthalate is preferably used from the viewpoint of easy formation of a base film having desired toughness.

The thickness of the base film of the touch sensor panel is preferably 50 μm or less, more preferably 30 μm or less, from the viewpoint of easy formation of a laminate having excellent bending resistance. The thickness of the base film of the touch sensor panel may be, for example, 5 μm or more.

The touch sensor panel can be manufactured, for example, as follows. In method 1, a base film is first laminated on a substrate via an adhesive layer. A patterned transparent conductive layer is formed on a substrate film by photolithography. By applying heat, the substrate and the base film are separated, resulting in a touch sensor panel including the transparent conductive layer and the base film. The substrate is not particularly limited as long as it maintains flatness and has heat resistance, and is preferably a glass substrate.

In method 2, a material for forming a separation layer is first coated on a substrate to form the separation layer. The protective layer is formed by coating on the separation layer as needed. The protective layer may be formed in such a manner that the protective layer is not formed at a portion where the pad pattern layer is formed. A patterned transparent conductive layer is formed on the separation layer (or the protective layer) by photolithography. An insulating layer is formed on the transparent conductive layer in such a manner as to fill in the electrode pattern layer. A protective film is laminated on the insulating layer by using a releasable adhesive, and the protective film is transferred from the insulating layer to the separation layer to separate the substrate. By peeling the peelable protective film, a touch sensor panel having an insulating layer/transparent conductive layer/(protective layer)/separation layer in this order can be obtained.

When the substrate film is included, the thickness of the touch sensor panel may be, for example, 5 μm or more and 2000 μm or less, or may be 5 μm or more and 100 μm or less.

When the base film is not included, the thickness of the touch sensor panel is, for example, 0.5 μm or more and 10 μm or less, preferably 5 μm or less.

In the case where the laminate includes an organic EL panel, a touch sensor panel, and a front panel, examples of the layer structure of the laminate include a front panel, a laminate, a touch sensor panel, an organic EL panel, a front panel, a touch sensor panel, a laminate, and an organic EL panel.

[ layer Structure of laminate ]

The laminate 200 shown in fig. 2 is formed by laminating a front panel 21, a 3 rd adhesive layer 22, a linear polarizing plate 23, a 1 st adhesive layer 24, a liquid crystal coating layer 25, a 2 nd adhesive layer 26, and an organic EL panel 27 in this order from the viewing side. The linear polarization plate 23 is provided with a base film 28, an alignment film 29, a linear polarization layer 30, and a protective layer (OC layer) 31 in this order from the viewing side.

The laminate 300 shown in fig. 3 is formed by laminating a front panel 41, a 3 rd adhesive layer 42, a linear polarizing plate 43, a 1 st adhesive layer 44, a liquid crystal coating 45, a 2 nd adhesive layer 46, and an organic EL panel 47 in this order from the viewing side. The linear polarization plate 43 is provided with a base film 48, a protective layer (HC layer) 49, an alignment film 50, a linear polarization layer 51, and a protective layer (OC layer) 52 in this order from the viewing side.

[ method for producing laminate ]

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

In the case where the linearly polarizing layer is a stretched film or a stretched layer to which a dye having absorption anisotropy is adsorbed, the method for producing the linearly polarizing layer may be produced as described above in the description of the stretched film or the stretched layer to which a dye having absorption anisotropy is adsorbed.

In the case where the linearly polarizing layer is a film obtained by coating and curing the dye having absorption anisotropy, the linearly polarizing layer may be formed on the substrate via an alignment film. The linearly polarizing layer can be formed by applying a composition for forming a linearly polarizing layer containing a dichroic dye and a polymerizable liquid crystal compound and curing the composition. The composition for forming a linearly polarized layer preferably contains a polymerization initiator, a leveling agent, a solvent, a photosensitizer, a polymerization inhibitor, a leveling agent, and the like in addition to the dichroic dye and the polymerizable liquid crystal compound.

The liquid crystal coating layer can be produced by applying a liquid crystal coating layer-forming composition containing a polymerizable liquid crystal compound to a substrate and an alignment film in the presence of the substrate and polymerizing the polymerizable liquid crystal compound. The composition for forming a liquid crystal coating layer further contains a solvent, a polymerization initiator, and may further contain a photosensitizer, a polymerization inhibitor, a leveling agent, and the like. The substrate and the alignment film may be assembled to the liquid crystal coating layer, or may be peeled off from the liquid crystal coating layer without being a constituent element of the laminate.

The coating, drying and polymerization of the composition for forming a linearly polarized layer and the composition for forming a liquid crystal coating layer can be carried out by a conventionally known coating method, drying method and polymerization method.

For example, as a coating method of the composition for forming a linearly polarizing layer and the composition for forming a liquid crystal coating layer, a bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a die coating method, and the like can be used.

The polymerization method of the polymerizable liquid crystal compound may be selected according to the type of the polymerizable group of the polymerizable liquid crystal compound. If the polymerizable group is a photopolymerizable group, polymerization can be performed by a photopolymerization method. If the polymeric group is a thermally polymerizable group, polymerization can be performed by a thermal polymerization method. In the method for producing a liquid crystal coating layer of the present embodiment, a photopolymerization method is preferable. The photopolymerization method does not necessarily require heating the transparent substrate to a high temperature, and thus a transparent substrate having low heat resistance can be used. The photopolymerization method is performed by irradiating a film containing a composition for forming a linearly polarized layer or a composition for forming a liquid crystal coating layer containing a polymerizable liquid crystal compound with visible light or ultraviolet light. Ultraviolet light is preferred from the viewpoint of ease of handling.

The adhesive layer may be prepared in the form of an adhesive sheet. The adhesive sheet can be produced, for example, by: an adhesive composition is dissolved or dispersed in an organic solvent such as toluene or ethyl acetate to prepare an adhesive liquid, a layer containing an adhesive is formed in a sheet form on a release film on which a release treatment is performed, and another release film is further bonded to the adhesive layer. The layers may be bonded by bonding an adhesive sheet from which one release film is peeled to one layer, followed by peeling the other release film to bond the other layer.

As a method of applying the adhesive liquid to the release film, a usual application technique using a die coater, comma coater, reverse roll coater, gravure coater, bar coater, wire bar coater, blade coater, air knife coater, or the like may be used.

The release film is preferably composed of a plastic film and a release layer. Examples of the plastic film include polyester films such as polyethylene terephthalate films, polybutylene terephthalate films and polyethylene naphthalate films, and polyolefin films such as polypropylene films. The release layer may be formed of, for example, a composition for forming a release layer. The main component (resin) constituting the composition for forming a release layer is not particularly limited, and examples thereof include silicone resins, alkyd resins, acrylic resins, long-chain alkyl resins, and the like.

The thickness of the adhesive layer can be adjusted according to the application conditions of the adhesive liquid, respectively. In order to reduce the thickness of the adhesive layer, it is effective to reduce the application thickness.

The laminate can be produced by cutting an elongated film formed by bonding a linearly polarizing layer and a liquid crystal coating layer via an adhesive layer to a predetermined size. The laminate may be produced by bonding a linearly polarizing layer cut into a predetermined size in advance to a liquid crystal coating layer with an adhesive layer.

< image display device >)

An image display device according to another embodiment of the present invention includes the above laminate. The display device is not particularly limited, and examples thereof include image display devices such as organic EL display devices, inorganic EL display devices, liquid crystal display devices, and electroluminescent display devices. The image display device may have a touch panel function. The laminate is suitable for a flexible display having flexibility capable of bending or bending.

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

The image display device can be used as mobile devices such as smart phones, tablet computers and the like, televisions, digital photo frames, electronic labels, measuring instruments, meters, office equipment, medical equipment, electric computing equipment and the like. The image display device suppresses distortion of the reflection image reflected on the front surface, and therefore has excellent visibility of the screen.

Examples

The present invention will be described in further detail with reference to examples. In the examples, "%" and "parts" are mass% and parts unless otherwise specified.

[ method for measuring storage modulus at 25 ]

The storage modulus of the adhesive layer at a temperature of 25 ℃ was measured by the following method. The adhesive layers used in examples and comparative examples were laminated in such a manner that the thickness became 0.2 mm. A cylinder having a diameter of 8mm was punched out of the obtained adhesive layer, and this was used as a sample for measuring the storage modulus at a temperature of 25 ℃. For the above samples, storage modulus (Pa) at 25℃was measured by a torsional shear method using a viscoelasticity measuring apparatus (MCR 300, manufactured by Physica Co., ltd.) in accordance with JIS K7244-6.

(measurement conditions)

Normal force FN:1N

Strain γ:1%

Frequency: 1Hz

Temperature: 25 DEG C

[ thickness of layer ]

The thickness of the adhesive layer was measured using a contact film thickness measuring apparatus (MS-5C, nikon, inc.). Among them, the polarizer layer and the alignment film were measured using a laser microscope (OLS 4100 manufactured by olympus corporation).

[ method for measuring modulus of elasticity in tension at a temperature of 23 ]

The tensile modulus of elasticity at a temperature of 23℃was measured as follows. Rectangular pieces 110mm long by 10mm short were cut out of the front panel or polyimide film (equivalent to a substitute for an organic EL panel) using a super cutter. Next, both ends of the measurement sample in the longitudinal direction were held by upper and lower clamps of a tensile tester (Autograph AG-Xplus tester manufactured by shimadzu corporation) so that the interval between the clamps became 5cm, and the measurement sample was stretched in the longitudinal direction of the measurement sample at a stretching speed of 4 mm/min under an environment of a temperature of 23 ℃ and a relative humidity of 55%, and the tensile elastic modulus at a temperature of 23 ℃ and a relative humidity of 55% was calculated from the slope of a straight line between 20 to 40MPa in the obtained stress-strain curve. In this case, the thickness for calculating the stress is measured by the method described above.

[ evaluation of bendability ]

The refolding test was performed at a temperature of 25℃and a relative humidity of 55% RH according to the procedure shown below.

(external folding test)

Rectangular pieces 110mm long by 10mm short were cut from the laminate using a super cutter. Next, as shown in fig. 4 (a), in the bending test machine having two jigs 501 and 502 capable of moving independently, the measuring sample 500 was bent with the front panel side as the outside and the direction parallel to the short side direction as the bending axis, and the ends of the measuring sample 500 on the long side were fixed to the jigs 501 and 502 with adhesive tapes, respectively, and the positions of the jigs 501 and 502 were adjusted so that the distance D between the jigs 501 and 502 became 70 mm. Then, as shown in fig. 4B, the jig 501 was operated in the direction of arrow a so that the interval D became 4.0mm (bending radius 2R), the measurement sample 500 was bent, and then the jig 501 was operated in the direction of arrow B, the interval D was set to 70mm, the bending was released, the series of operations was counted as 1, and the series of operations was repeated 20 ten thousand times successively. The moving speed of the jig 501 was 1.32 m/sec, and the time required for repeating 20 ten thousand times was 55.6 hours. After repeating 20 ten thousand times, the measurement sample was taken out from the bending tester, and observed with an optical microscope by transmitted light to confirm the occurrence of cracks.

And (2) the following steps: there is the occurrence of cracks.

X: no crack is generated.

[ front panel ]

As a window film as a front plate, a polyimide film (PI film, overall thickness: 40 μm, tensile elastic modulus: 6.8 GPa) was prepared.

[ 3 rd adhesive layer ]

A commercially available 3 rd adhesive sheet (CEF 3501, manufactured by 3M company in the united states) having a thickness of 50 μm sandwiched between 3 rd adhesive layers was prepared using release treated surfaces of 2 (heavy Sp, light Sp) release films each having a release treatment on one surface of a base film. The storage modulus of the 3 rd adhesive layer at a temperature of 25℃was 41kPa.

[ Linear polarization plate A ]

(substrate film)

As a base film, a triacetyl cellulose (TAC) film (25 μm thick, manufactured by konikama america corporation) was prepared.

(composition for Forming an alignment film)

Polymer 1 is a polymer having a photoreactive group comprising the following structural unit.

[ chemical formula 1]

The molecular weight of the obtained polymer 1 was determined by GPC and found to be 28200, mw/Mn1.82 and the monomer content was 0.5%.

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

(polymerizable liquid Crystal Compound)

The polymerizable liquid crystal compound represented by the formula (1-6) [ hereinafter, also referred to as the compound (1-6) ] and the polymerizable liquid crystal compound represented by the formula (1-7) [ hereinafter, also referred to as the compound (1-7) ].

[ chemical formula 2]

[ chemical formula 3]

Compounds (1-6) and (1-7) were synthesized by the method described in Lub et al, recl. Trav. Chim. Pays-Bas,115, 321-328 (1996).

(dichromatic pigment)

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

[ chemical formula 4]

[ chemical formula 5]

[ chemical formula 6]

(composition for Forming Linear polarization layer)

The composition for forming a linearly polarizing layer is prepared by: 75 parts by mass of compound (1-6), 25 parts by mass of compound (1-7), 2.5 parts by mass of each of azo pigments represented by the above-mentioned formulas (2-1 a), (2-1 b), (2-3 a) as dichroic dyes, 6 parts by mass of 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one (Irgacure 369, manufactured by BASF Japan) as a polymerization initiator, and 1.2 parts by mass of a polyacrylate compound (BYK-361N, manufactured by BYK-Chemie) as a leveling agent were mixed into 400 parts by mass of toluene as a solvent, and the resultant mixture was stirred at 80℃for 1 hour.

(composition for protective layer (OC layer))

The composition for protective layer was prepared by mixing 3 parts by mass of a polyvinyl alcohol resin powder (manufactured by Kuraray, average polymerization degree 18000, trade name: KL-318) and 1.5 parts by mass of a polyamide epoxy resin (a crosslinking agent, manufactured by Sumika Chemtex Co., ltd., trade name: SR650 (30)) with 100 parts by mass of water.

(production of Linear polarization plate A)

Corona treatment is applied to the substrate film. The conditions for the corona treatment were set to an output of 0.3kW and a treatment speed of 3 m/min. Then, passing a rod over the substrate filmThe composition for forming an alignment film was coated by the coating method, and dried by heating in a drying oven at 80℃for 1 minute. The obtained dried film was subjected to a polarized UV irradiation treatment to form an alignment film. In the polarized light UV treatment, a light transmission wire grid (UIS-27132 #, manufactured by Ushio electric Co., ltd.) irradiated from a UV irradiation device (SPOTCURE SP-7; manufactured by Ushio electric Co., ltd.) was used, and the cumulative light amount measured at a wavelength of 365nm was 100mJ/cm ² Is carried out under the condition of (2). The thickness of the alignment film was 100nm.

The composition for forming a linearly polarized layer was applied to the formed alignment film by a bar coating method, and after drying by heating in a drying oven at 120℃for 1 minute, it was cooled to room temperature. Using the above UV irradiation apparatus to accumulate a light quantity of 1200mJ/cm ² The dried film was irradiated with ultraviolet light (365 nm standard), whereby a linearly polarized layer was formed. The thickness of the obtained linearly polarized layer was measured by a laser microscope (OLS 3000, manufactured by Olin Bas Co., ltd.) and found to be 1.8. Mu.m. Thus, a laminate composed of "substrate film/alignment film/linear polarization layer" was obtained.

The composition for a protective layer (OC layer) was applied to the linearly polarized layer formed by a bar coating method, and the composition was applied so that the thickness after drying became 1.0 μm, and dried at 80 ℃ for 3 minutes. Thus, a linear polarizing plate a composed of "substrate film/alignment film/linear polarizing layer/protective layer (OC layer)" was obtained.

[ Linear polarization plate B ]

(substrate film)

As a base film, a polyethylene terephthalate (PET) film (thickness 100 μm) was prepared.

(composition for protective layer (HC layer))

A composition for a protective layer (HC layer) was prepared by mixing 2.8 parts by mass of a dendrimer acrylate having an 18-functional acrylic group (Miramer SP1106, miwon), 6.6 parts by mass of a urethane acrylate having a 6-functional acrylic group (Miramer PU-620d, miwon), 0.5 part by mass of a photopolymerization initiator (Irgacure-184, basf), 0.1 part by mass of a leveling agent (BYK-3530, BYK), and 90 parts by mass of Methyl Ethyl Ketone (MEK).

The composition for forming an alignment film, the composition for forming a linearly polarizing layer, and the composition for forming a protective layer (OC layer) are each the compositions described in the item [ linearly polarizing plate a ].

(production of Linear polarization plate B)

The composition for the protective layer (HC layer) was applied to the base film by a bar coating method, and dried by heating in a drying oven at 80 ℃ for 3 minutes. The obtained dried film was irradiated with an exposure of 500mJ/cm by using a UV irradiation apparatus (SPOTCURE SP-7, manufactured by Ushio Motor Co., ltd.) ² (365 nm basis) UV light to form a protective layer (HC layer). The thickness of the protective layer (HC layer) was measured by a laser microscope (OLS 3000 manufactured by Olympic Co., ltd.) and found to be 2.0. Mu.m. Thus, a laminate composed of the "base film/protective layer (HC layer)" was obtained.

The protective layer (HC layer) side of the laminate composed of the "base film/protective layer (HC layer)" was subjected to corona treatment 1 time. The conditions for the corona treatment were set to an output of 0.3kW and a treatment speed of 3 m/min. Then, the composition for forming an alignment film was coated on the protective layer (HC layer) by a bar coating method, and dried by heating in a drying oven at 80 ℃ for 1 minute. The obtained dry film was subjected to a polarized UV irradiation treatment to form a 1 st alignment film. In the polarized light UV treatment, a light transmission wire grid (UIS-27132 #, manufactured by Ushio electric Co., ltd.) irradiated from a UV irradiation device (SPOTCURE SP-7; manufactured by Ushio electric Co., ltd.) was used, and the cumulative light amount measured at a wavelength of 365nm was 100mJ/cm ² Is carried out under the condition of (2). The thickness of the alignment film was 100nm.

The composition for forming a linearly polarized layer was applied to the formed alignment film by a bar coating method, and after drying by heating in a drying oven at 120℃for 1 minute, it was cooled to room temperature. Using the above UV irradiation apparatus to accumulate a light quantity of 1200mJ/cm ² The dried film was irradiated with ultraviolet light (365 nm standard), whereby a linearly polarized layer was formed. The thickness of the obtained linearly polarized layer was measured by a laser microscope (OLS 3000, manufactured by Olin Bas Co., ltd.) and found to be 1.8. Mu.m. Thus, a laminate composed of "base film/protective layer (HC layer)/alignment film/linear polarization layer" was obtained.

The composition for a protective layer (OC layer) was applied to the formed polarizing layer by a bar coating method, and the composition was applied so that the thickness after drying became 1.0 μm, and dried at 80 ℃ for 3 minutes. Thus, a laminate composed of "base film/protective layer (HC layer)/alignment film/linear polarization layer/protective layer (OC layer)" was obtained. The base film was peeled off immediately before use, and a linear polarizing plate B composed of "protective layer (HC layer)/alignment film/linear polarizing layer/protective layer (OC layer)" was obtained.

[ adhesive layer A ]

As the pressure-sensitive adhesive sheet a having the pressure-sensitive adhesive layer a, a commercially available pressure-sensitive adhesive sheet was used in which an acrylic pressure-sensitive adhesive layer having a thickness of 5 μm was sandwiched between release treated surfaces of 2 release films (heavy spacers and light spacers) each having a release treatment on one surface of a polyethylene terephthalate film (base film) having a thickness of 38 μm. The adhesive layer A after the release film was removed from the adhesive sheet A had a storage modulus G'1 of 1400kPa at a temperature of 25 ℃.

[ adhesive layer B ]

As the pressure-sensitive adhesive sheet B having the pressure-sensitive adhesive layer B, a commercially available pressure-sensitive adhesive sheet (CEF 3501 manufactured by 3M company in the united states) having a pressure-sensitive adhesive layer having a thickness of 25 μm sandwiched between release treated surfaces of 2 release films (heavy spacers and light spacers) each having a release treatment on one surface of a base film was used. The adhesive layer B after the release film was removed from the adhesive sheet B had a storage modulus G'2 at a temperature of 25℃of 41kPa.

[ liquid Crystal coating ]

(1 st liquid Crystal cured retarder)

As the 1 st liquid crystal cured retardation layer, a layer for imparting a retardation of λ/4, which is composed of a layer cured with a nematic liquid crystal compound, an alignment layer, and a transparent substrate, was prepared. The total thickness of the layer obtained by curing the nematic liquid crystal compound and the alignment layer was 2. Mu.m. The layer formed by curing the nematic liquid crystal compound is formed by applying a composition for forming a retardation layer containing the nematic liquid crystal compound onto an alignment layer formed on a transparent substrate and curing the composition.

(2. Liquid Crystal cured phase-difference layer)

Polyethylene terephthalate with a thickness of 38. Mu.mAn alcohol ester substrate was used as a transparent substrate, and one surface thereof was coated with a composition for a vertical alignment layer so that the film thickness became 3. Mu.m, and irradiated with 20mJ/cm ² Is used to produce an alignment layer. As the composition for the vertical alignment layer, a composition prepared by mixing 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, dipentaerythritol triacrylate, and bis (2-ethyleneoxyethyl) ether in an amount of 1:1:4:5, and a polymerization initiator, a LUCIRIN (registered trademark) TPO, was added in a proportion of 4%.

Next, a composition for forming a retardation layer containing a photopolymerizable nematic liquid crystal (RMM 28B, manufactured by Merck corporation) was applied to the alignment layer formed by die coating. Here, as the solvent in the liquid crystal composition, methyl Ethyl Ketone (MEK), methyl isobutyl ketone (MIBK) and Cyclohexanone (CHN) having a boiling point of 155 ℃ were used in a mass ratio (MEK: MIBK: CHN) of 35:30:35, and a solvent mixture obtained by mixing the above components in proportion. Then, the composition for forming a retardation layer, which is prepared so that the solid content becomes 1 to 1.5g, is applied to the alignment layer so that the application amount becomes 4 to 5g (wet).

After the composition for forming the retardation layer was applied to the alignment layer, the drying temperature was set to 75 ℃, and the drying time was set to 120 seconds, to carry out the drying treatment. Then, the liquid crystal compound was polymerized by Ultraviolet (UV) irradiation, and a positive C layer composed of a layer obtained by curing a photopolymerizable nematic liquid crystal compound, an alignment layer, and a transparent substrate was obtained. The total thickness of the layer obtained by curing the photopolymerizable nematic liquid crystal compound and the alignment layer was 4. Mu.m.

(preparation of liquid Crystal coating)

The 1 st liquid crystal cured retardation layer and the 2 nd liquid crystal cured retardation layer are bonded to each other with an ultraviolet ray cured adhesive so that the respective liquid crystal cured retardation layers (surfaces opposite to the transparent substrate) are bonded to each other. Then, the ultraviolet-curable adhesive is cured by irradiation with ultraviolet rays. The thickness of the ultraviolet-curable adhesive after curing was 2. Mu.m. Thus, a liquid crystal coating layer composed of layers of "1 st liquid crystal cured retardation layer (2 μm)/adhesive layer (thickness 2 μm)/2 nd liquid crystal cured retardation layer (thickness 4 μm)" was produced.

[ organic EL Panel ]

As a substitute for an organic EL panel, a polyimide film (PI film, overall thickness: 75 μm, tensile elastic modulus 6.96 GPa) was prepared.

Example 1 >

The adhesive layer a exposed by peeling the light spacer from the adhesive sheet a was bonded to the protective layer 2 side of the linear polarizing plate a, and a laminate A1 was obtained. The bonding surface was subjected to double-sided corona treatment (output power 0.3kW, speed 3 m/min) in advance.

The adhesive layer a exposed by peeling the heavy spacers from the laminate A1 was bonded to the surface of the liquid crystal coating layer from which the base film for forming the 1 st liquid crystal cured retardation layer was peeled, to obtain a laminate A2. The bonding surface was subjected to double-sided corona treatment (output power 0.3kW, speed 3 m/min) in advance.

The adhesive layer a exposed by peeling the light spacer from the other adhesive sheet a was bonded to the surface of the laminate A2 from which the base film for forming the 2 nd liquid crystal cured retardation layer was peeled, to obtain a laminate A3. The bonding surface was subjected to double-sided corona treatment (output power 0.3kW, speed 3 m/min) in advance.

The 3 rd adhesive layer exposed by peeling the light spacer from the 3 rd adhesive sheet was bonded to the front panel, and a laminate A4 was obtained. The bonding surface was subjected to double-sided corona treatment (output power 0.3kW, speed 3 m/min) in advance.

The heavy spacer was peeled off from the laminate A4 and bonded to the protective layer 1 side of the laminate A3, to obtain a laminate A5. The bonding surface was subjected to double-sided corona treatment (output power 0.3kW, speed 3 m/min) in advance.

The heavy separator of the laminate A5 was peeled off, and a substitute (polyimide film) corresponding to an organic EL panel was bonded to obtain a laminate of example 1 having the structure shown in fig. 2. The results are shown in Table 1.

Example 2, comparative examples 1 and 2 >, and method of producing the same

Laminates of example 2 and comparative examples 1 and 2 were produced in the same manner as in example 1, except that the linear polarizing plate and the adhesive layer shown in table 1 were used. The results are shown in Table 1.

TABLE 1

Description of the reference numerals

100. 200, 300: laminate, 10, 30, 51: linear polarization layers, 11, 24, 44: adhesive layer 1, 12, 25, 45: liquid crystal coating, 13, 26, 46: adhesive layer 2, 21, 41: front panel, 22, 42: 3 rd adhesive layer, 23, 43: linear polarizing plates, 27, 47: organic EL panels, 28, 48: substrate film, 49: protective layer (HC layer), 29, 50: alignment films, 31, 52: protective layer (OC layer), 500: measurement samples, 501, 502: clamp

Claims

1. A laminate comprising a linear polarizing layer, a 1 st adhesive layer, a liquid crystal coating layer and a 2 nd adhesive layer laminated in this order,

when the storage modulus of the 1 st adhesive layer at a temperature of 25 ℃ is set to G '1 and the storage modulus of the 2 nd adhesive layer at a temperature of 25 ℃ is set to G'2, the following condition (1) is satisfied, wherein the units of G '1 and G'2 are kPa,

(1) G '1 is greater than or equal to 1000kPa and G'2 is greater than or equal to 1000kPa.

2. The laminate according to claim 1, wherein the linearly polarizing layer comprises a cured product of a composition containing a polymerizable liquid crystal compound and 1 or more azo pigments, and an alignment film.

3. The laminate according to claim 1 or 2, wherein the liquid crystal coating layer is formed of 1 layer or multiple layers.

4. The laminate according to any one of claims 1 to 3, wherein at least 1 protective layer selected from a thermoplastic resin film and a cured resin layer is provided on the side of the linearly polarized layer opposite to the 1 st adhesive layer.

5. The laminate according to claim 4, wherein a front panel is provided on the opposite side of the protective layer from the linearly polarizing layer via a 3 rd adhesive layer.

6. The laminate according to claim 5, wherein the front panel has a tensile elastic modulus of 4.0GPa or more at a temperature of 23 ℃.

7. The laminate of claim 5 or 6, wherein the 3 rd adhesive layer has a storage modulus of 50KPa or less at a temperature of 25 ℃.

8. The laminate according to any one of claims 1 to 7, wherein an organic EL panel is provided on the side of the 2 nd adhesive layer opposite to the liquid crystal coating layer.

9. The laminate according to any one of claims 1 to 8, wherein the organic EL panel has a tensile elastic modulus of 4.0GPa or more at a temperature of 23 ℃.

10. An image display device comprising the laminate according to any one of claims 1 to 9.