JP2023154554A - Laminate and image display device - Google Patents

Abstract

To provide a laminate which comprises a front plate having an ultra-thin glass, an adhesive layer, and a polarizing film and offers improved handleability and fixability.SOLUTION: A laminate is provided, comprising a front plate, adhesive layer, and polarizing film arranged in the described order, the front plate comprising an ultra-thin glass and hard coat layer, the adhesive layer having a storage modulus of 0.2 MPa or less at 25°C, and the polarizing film being composed of a cured liquid crystal layer containing a cured product of a polymerizable liquid crystal compound.SELECTED DRAWING: Figure 1

Description

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

Patent Document 1 proposes a glass substrate laminate in which a hard coat layer is provided on thin glass as a flexible glass substrate for use in a flexible display window.

Korean Patent No. 10-2276160

A front plate having ultra-thin glass is likely to crack when bonded to an optical member and when the image display device is bent after being incorporated into the image display device.

An object of the present invention is to provide a laminate including a front plate having ultra-thin glass, an adhesive layer, and a polarizing film, which has improved handling properties and flexibility. .

The present invention provides the following laminate and image display device.
[1] Includes a front plate, an adhesive layer, and a polarizing film in this order,
The front plate includes ultra-thin glass and a hard coat layer,
The storage modulus of the adhesive layer at a temperature of 25° C. is 0.2 MPa or less,
The polarizing film is a laminate comprising a cured liquid crystal layer containing a cured product of a polymerizable liquid crystal compound.
[2] The laminate according to [1], wherein the ultra-thin glass has a thickness of 50 μm or less.
[3] The laminate according to [1], wherein the hard coat layer has a thickness of 10 μm or more.
[4] The laminate according to [2], wherein the hard coat layer has a thickness of 10 μm or more.
[5] The laminate according to [1] to [4], wherein the adhesive layer has a storage modulus of 0.01 MPa or more at a temperature of 25°C.
[6] The laminate according to any one of [1] to [4], wherein the adhesive layer has a thickness of 30 μm or less.
[7] The laminate according to [5], wherein the adhesive layer has a thickness of 30 μm or less.
[8] An image display device comprising the laminate according to any one of [1] to [4].
[9] An image display device comprising the laminate according to [5].
[10] An image display device comprising the laminate according to [6].
[11] An image display device comprising the laminate according to [7].

The present invention further provides the following laminate and image display device.
[a] Includes a front plate, an adhesive layer, and a polarizing film in this order,
The front plate includes ultra-thin glass and a hard coat layer,
The storage modulus of the adhesive layer at a temperature of 25° C. is 0.2 MPa or less,
The polarizing film is a laminate comprising a cured liquid crystal layer containing a cured product of a polymerizable liquid crystal compound.
[b] The laminate according to [a], wherein the ultra-thin glass has a thickness of 50 μm or less.
[c] The laminate according to [a] or [b], wherein the hard coat layer has a thickness of 10 μm or more.
[d] The laminate according to any one of [a] to [c], wherein the adhesive layer has a storage modulus of 0.01 MPa or more at a temperature of 25°C.
[e] The laminate according to any one of [a] to [d], wherein the adhesive layer has a thickness of 30 μm or less.
[f] An image display device comprising the laminate according to any one of [a] to [e].

According to the present invention, it is possible to provide a laminate including a front plate having ultra-thin glass, an adhesive layer, and a polarizing film, which has improved handling properties and flexibility. .

1 is a schematic cross-sectional view showing an example of the layer structure of a laminate according to the present invention. It is a schematic sectional view showing another example of the layer composition of the layered product concerning the present invention. FIG. 3 is a schematic cross-sectional view showing another example of the layer structure of the laminate according to the present invention. It is a schematic diagram explaining the method of a flexibility test.

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to the following embodiments. In all the drawings below, each component is shown adjusted to an appropriate scale to make it easier to understand, and the scale of each component shown in the drawings does not necessarily match the actual scale of the component.

<Laminated body>
A laminate according to one embodiment of the present invention includes a front plate, an adhesive layer, and a polarizing film in this order, and the front plate includes ultra-thin glass and a hard coat layer, and the adhesive layer has a temperature of 25°C. The storage modulus is 0.2 MPa or less, and the polarizing film is a laminate composed of a cured liquid crystal layer containing a cured product of a polymerizable liquid crystal compound.

FIG. 1 shows a schematic cross-sectional view of a laminate according to one embodiment of the present invention. In the laminate 100 shown in FIG. 1, a front plate 10, an adhesive layer 11, and a polarizing plate 12 are laminated in this order. The adhesive layer 11 may be placed in contact with the front plate 10 and the polarizing plate 12. Front plate 10 includes ultra-thin glass 14 and hard coat layer 13. In the polarizing plate 12, a base film 15, an alignment film 16, a polarizing film 17, and a protective layer 18 are laminated in order from the viewing side (front plate 10 side). In addition to the above-mentioned layers, the laminate 100 can further include other layers such as a retardation plate, a bonding layer, an organic EL panel, a touch sensor, and the like.

The laminate 100 can be bent with the front plate 10 side facing inside or outside with respect to the bending axis, preferably with the front plate 10 side facing inside with respect to the bending axis. Being able to bend means that the laminate can be bent without causing cracks. Bending includes a form of bending in which a curved surface is formed in the bent portion. In the form of bending, the bending radius of the bent inner surface is not particularly limited. Furthermore, bending includes a form of refraction in which the refraction angle of the inner surface is greater than 0° and less than 180°, and a form of folding in which the bending radius of the inner surface is close to zero or the refraction angle of the inner surface is 0°. . The laminate of the present invention is suitable for flexible displays because it can be bent.

When the laminate 100 is repeatedly bent in the evaluation of flexibility described below, the bending radius at which cracks are less likely to occur may be, for example, 4 mm or less, preferably 2 mm or less, and more preferably 1.5 mm or less. When the laminate 100 is repeatedly bent with a bending radius of 1.5 mm in the evaluation of flexibility described below, the number of bends at which cracks first occur is preferably 200,000 times or more, more preferably 300,000 times. or more, more preferably 400,000 times or more, particularly preferably 500,000 times or more.

The thickness of the laminate 100 is not particularly limited as it varies depending on the function required of the laminate and the use of the laminate, but is, for example, 30 μm or more and 4000 μm or less, preferably 2000 μm or less, and more preferably 1000 μm or less. be. In this specification, the thickness of the laminate and each layer can be measured according to the thickness measurement method described in Examples described below.

The planar shape of the laminate 100 may be, for example, a rectangular shape, preferably a rectangular shape having long sides and short sides, and more preferably a rectangular shape. When the shape of the laminate 100 in the plane direction is a rectangle, the length of the long side may be, for example, 10 mm or more and 1400 mm or less, and preferably 600 mm or less. The length of the short side is, for example, 5 mm or more and 800 mm or less, preferably 500 mm or less, and more preferably 300 mm or less. The corners of each layer constituting the laminate may be rounded, the ends may be cut out, or holes may be formed.

(Front plate)
The front plate 10 constitutes the outermost surface on the viewing side of the image display device, and can have a function of protecting the front surface (screen) of the image display device. The front plate 10 can be what is called a window film. Front plate 10 includes ultra-thin glass 14 and hard coat layer 13. The hard coat layer may be placed only on one side of the ultra-thin glass, or may be placed on both sides of the ultra-thin glass. In this specification, glass having a thickness of 50 μm or less is referred to as ultra-thin glass.

The thickness of the front plate 10 may be, for example, 30 μm or more and 200 μm or less, preferably 100 μm or less, and more preferably 50 μm or less.

The ultra-thin glass 14 can have a thickness of, for example, 50 μm or less. By using ultra-thin glass having a thickness of 50 μm or less, the laminate can be made thinner, and the flexibility and translucency of the laminate tend to be easily improved. The thickness of the ultra-thin glass 14 is preferably 45 μm or less, more preferably 40 μm or less, even more preferably 35 μm or less, particularly preferably 30 μm or less. The thickness of the ultra-thin glass 14 is usually 10 μm or more, and preferably 15 μm or more from the viewpoint of improving the impact resistance of the laminate.

As the ultra-thin glass 14, it is preferable to use chemically strengthened glass which has excellent strength and translucency. By using chemically strengthened glass, the impact resistance of the laminate can be improved while maintaining flexibility. Chemically strengthened glass can be obtained by chemical ion exchange treatment of glass. Through chemical ion exchange treatment, the strength of the glass surface can be improved by partially replacing sodium ions and lithium ions on the glass surface with potassium ions having a larger ionic radius. Formation of a thin compressive stress layer improves surface strength. Examples of the glass used for chemically strengthened glass include aluminosilicate glass, soda lime glass, borosilicate glass, lead glass, alkali barium glass, and aluminoborosilicate glass.

The chemical ion exchange treatment can be performed by immersing the glass in an ion replacement solution heated above its melting point or by directly applying a paste-like ion replacement solution to the glass. Ion displacement solutions include those based on potassium nitrate, potassium carbonate, potassium bicarbonate, potassium phosphate, potassium sulfate, and potassium hydroxide. Among these, potassium nitrate (330°C) is preferred because it has a melting point lower than the melting point of glass (usually 500°C or more and 600°C or less) and is easy to handle.

Etching treatment may be performed before the chemical ion exchange treatment to thin the glass. The etching process can also be performed using hydrofluoric acid or a mixture of hydrofluoric acid, an aqueous ammonium fluoride solution, and an organic acid such as formic acid, acetic acid, propionic acid, etc. as a chemical treatment solution. Using these, etching can be performed by spraying, dipping, etc. The etching process may be performed using an inert gas containing fluorine as an etching gas, such as He gas or Ar gas containing at least one of CF ₄ , C ₃ F ₈ , C ₂ F ₆ , XeF _{2 ,} etc. . Specifically, etching can be performed by turning an inert gas containing fluorine diluted with He gas or Ar gas into plasma under atmospheric pressure to liberate fluorine from carbon fluoride.

The front plate 10 has a hard coat layer 13 on at least one surface of an ultra-thin glass 14. Providing the hard coat layer 13 tends to make it easier to handle the laminate 100. Further, by providing the hard coat layer 13, hardness and scratch resistance can be improved. When the image display device on which the front plate 10 is arranged is a touch panel type image display device, the front plate 10 having the hard coat layer 12 is suitable because the surface of the front plate becomes a touch surface.

The hard coat layer 13 may be formed on one surface or both surfaces of the ultra-thin glass 14. When formed on both surfaces of the ultra-thin glass 14, the handling of the laminate 100 tends to be easier. When the hard coat layer 13 is formed on one surface of the ultra-thin glass 14, it is preferably formed on the surface that becomes the viewing side when the laminate 100 is bonded to an image display device.

The hard coat layer 13 can be, for example, a cured layer of ultraviolet curable resin. Examples of the ultraviolet curable resin include (meth)acrylic resin, silicone resin, polyester resin, urethane resin, amide resin, and epoxy resin. Hard coat layer 13 may contain additives to improve hardness. The additive is not limited and may include inorganic fine particles, organic fine particles, or a mixture thereof.

The hard coat layer 13 may have a single layer structure, or may have a multilayer structure consisting of two or more layers. When the hard coat layer 13 has a multilayer structure, the handleability of the laminate tends to be improved. When the hard coat layer 13 has a multilayer structure, the thickness of each layer and the material constituting each layer may be different from each other or may be the same. The multilayer structure may consist of two or three layers, preferably two layers.

The thickness of the hard coat layer 13 may be, for example, 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and may be, for example, 50 μm or less, 40 μm or less, or 30 μm or less.

When the hard coat layer 13 has a multilayer structure or is arranged on both sides of ultra-thin glass, the total thickness of all hard coat layers may be, for example, 10 μm or more, preferably 15 μm or more, and more preferably is 20 μm or more, and may be, for example, 50 μm or less, 40 μm or less, or 30 μm or less.

It is also preferable that a wear-resistant layer is formed on the visible side of the hard coat layer 13 in order to improve wear resistance and prevent contamination by sebum or the like. The front plate 10 can have a wear-resistant layer, and the wear-resistant layer can be a layer that constitutes the viewing side surface of the front plate 10. The wear-resistant layer can include a structure derived from a fluorine compound. As the fluorine compound, a compound having a silicon atom and having a hydrolyzable group such as an alkoxy group or a halogen on the silicon atom is preferable. A coating film can be formed by the dehydration condensation reaction of the hydrolyzable group, and the adhesion of the wear-resistant layer can be improved by reacting with active hydrogen on the surface of the base material. Further, the fluorine compound preferably has a perfluoroalkyl group or a perfluoropolyether structure because it can impart water repellency. Particularly preferred are fluorine-containing polyorganosiloxane compounds having a perfluoropolyether structure and a long-chain alkyl group having 4 or more carbon atoms. It is also preferable to use two or more types of fluorine compounds. The fluorine compound that is preferably further included is a fluorine-containing organosiloxane compound containing an alkylene group having 2 or more carbon atoms and a perfluoroalkylene group.

The thickness of the wear-resistant layer may be, for example, 1 nm or more and 20 nm or less. Further, the wear-resistant layer has water repellency, and has a water contact angle of, for example, about 110 to 125 degrees. The contact angle hysteresis and sliding angle measured by the sliding method are about 3 to 20° and about 2 to 55°, respectively. Furthermore, the wear-resistant layer may contain a silanol condensation catalyst, an antioxidant, a rust preventive agent, an ultraviolet absorber, a light stabilizer, a fungicide, an antibacterial agent, a biofouling inhibitor, and a disinfectant, within a range that does not impede the effects of the present invention. It may contain various additives such as odorants, pigments, flame retardants, and antistatic agents.

A primer layer may be provided between the wear-resistant layer and the hard coat layer. As the primer agent, there are, for example, an ultraviolet curing type, a thermosetting type, a moisture curing type, or a two-component curing type epoxy compound primer agent. Moreover, polyamic acid may be used as a primer agent, and it is also preferable to use a silane coupling agent. The thickness of the primer layer is, for example, 0.001 to 2 μm.

A method for obtaining a front plate including an abrasion resistant layer and a hard coat layer is to apply a primer agent as necessary on the hard coat layer, dry and harden it to form a primer layer, and then apply a fluorine compound. It can be formed by applying and drying a composition (a wear-resistant layer coating composition) containing the above-mentioned material. Examples of the coating method include dip coating, roll coating, bar coating, spin coating, spray coating, die coating, and gravure coating. Furthermore, before applying the primer agent or the wear-resistant layer coating composition, it is also preferable to subject the coated surface to a hydrophilic treatment such as plasma treatment, corona treatment, or ultraviolet treatment.

The front plate 10 may include a resin film to improve impact resistance. The resin film is not limited as long as it is a resin film that can transmit light. For example, triacetylcellulose, acetylcellulose butyrate, ethylene-vinyl acetate copolymer, propionylcellulose, butyrylcellulose, acetylpropionylcellulose, polyester, polystyrene, polyamide, polyetherimide, poly(meth)acrylic, polyimide, polyether Sulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polymethyl (meth)acrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene chloride Examples include films made of polymers such as phthalate, polycarbonate, and polyamideimide. These polymers can be used alone or in combination of two or more. When using a laminate for a flexible display, a resin film made of polymers such as polyimide, polyamide, polyamideimide, etc., which has excellent flexibility and can be configured to have high strength and high transparency. is preferably used. In this specification, "(meth)acrylic" means either acrylic or methacryl. "(Meta)" in (meth)acrylate and the like has the same meaning. The thickness of the resin film is, for example, 10 μm or more and 500 μm or less, preferably 20 μm or more and 100 μm or less.

(Adhesive layer)
The adhesive layer 11 may be a layer interposed between the front plate 10 and the polarizing plate 12 to bond them together. The adhesive layer may be, for example, a layer made of an adhesive or a layer obtained by subjecting this layer to some kind of treatment. The adhesive is also called a pressure-sensitive adhesive. In this specification, the term "adhesive" refers to adhesives other than adhesives (pressure-sensitive adhesives), and is clearly distinguished from adhesives. The adhesive layer may be one layer or may consist of two or more layers, but is preferably one layer.

The storage elastic modulus of the adhesive layer 11 at a temperature of 25° C. is 0.2 MPa or less, preferably 0.1 MPa or less, more preferably 0.05 MPa or less. The storage modulus of the adhesive layer 11 at a temperature of 25° C. is measured according to the measurement method described in the Examples section below. When the storage elastic modulus of the adhesive layer 11 at a temperature of 25° C. is 0.2 MPa or less, the flexibility of the laminate 100 tends to be easily improved.

The adhesive layer 11 is formed from an adhesive composition described below. The storage modulus of the adhesive layer 11 at a temperature of 25° C. can be determined by, for example, selecting the type of monomer constituting the (meth)acrylic polymer contained in the adhesive composition or adjusting the molecular weight of the (meth)acrylic polymer. The crosslinking density can be adjusted by adjusting the crosslinking density or the thickness of the pressure-sensitive adhesive layer by adjusting the amount of the crosslinking agent added, or by a combination of these methods. It is also possible to select and use one having a desired storage modulus from commercially available adhesives.

The adhesive layer 11 can be composed of an adhesive composition whose main component is a resin such as (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether. Among these, a pressure-sensitive adhesive composition whose base polymer is a (meth)acrylic resin having excellent transparency, weather resistance, heat resistance, etc. is suitable. The adhesive composition may be of an active energy ray curable type or a thermosetting type.

Examples of the (meth)acrylic resin (base polymer) used in the adhesive composition include butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-(meth)acrylate. Polymers or copolymers containing one or more types of (meth)acrylic esters such as ethylhexyl as monomers are preferably used. It is preferable to copolymerize a polar monomer with the base polymer. Examples of the polar monomer include (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl ( Examples include monomers having carboxyl groups, hydroxyl groups, amide groups, amino groups, epoxy groups, etc., such as meth)acrylates.

The pressure-sensitive adhesive composition may contain only the above base polymer, but usually further contains a crosslinking agent. Examples of crosslinking agents include metal ions with a valence of two or more that form carboxylic acid metal salts with carboxyl groups; polyamine compounds that form amide bonds with carboxyl groups; polyamine compounds that form amide bonds with carboxyl groups; Examples include epoxy compounds and polyols that form ester bonds with carboxyl groups; polyisocyanate compounds that form amide bonds with carboxyl groups. Among these, polyisocyanate compounds are preferred.

An active energy ray-curable adhesive composition has the property of being cured by irradiation with active energy rays such as ultraviolet rays or electron beams, and remains sticky and forms a film even before irradiation with active energy rays. It is an adhesive composition that can be closely adhered to adherends such as adhesives, etc., and has the property that it can be cured by irradiation with active energy rays to adjust the adhesive strength. The active energy ray-curable adhesive composition is preferably an ultraviolet ray-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. Furthermore, if necessary, a photopolymerization initiator, a photosensitizer, etc. may be included.

The adhesive composition contains fine particles, beads (resin beads, glass beads, etc.), glass fibers, resins other than the base polymer, tackifiers, fillers (metal powders and other inorganic powders) to impart light scattering properties. etc.), antioxidants, ultraviolet absorbers, dyes, pigments, colorants, antifoaming agents, corrosion inhibitors, antistatic agents, photopolymerization initiators, and other additives.

The adhesive layer 11 can be formed by applying a diluted solution of the adhesive composition in an organic solvent onto a base material and drying it. When an active energy ray-curable adhesive composition is used, a cured product having a desired degree of curing can be obtained by irradiating the formed adhesive layer with active energy rays.

The thickness of the adhesive layer 11 is, for example, preferably 1 μm or more and 100 μm or less, more preferably 50 μm or less, even more preferably 30 μm or less, and may be 10 μm or more.

[Polarizing film]
The polarizing film 17 is composed of a cured liquid crystal layer containing a cured product of a polymerizable liquid crystal compound. When the polarizing film 17 is composed of a cured liquid crystal layer containing a cured product of a polymerizable liquid crystal compound, the flexibility of the laminate 100 tends to be easily improved. A liquid crystal cured layer containing a cured product of a polymerizable liquid crystal compound is obtained by coating a base film with a composition containing a polymerizable dichroic dye having liquid crystal properties or a composition containing a polymerizable liquid crystal compound and a dichroic dye. The polarizing layer may be a layer obtained by curing the polarizing layer. Specifically, iodine and a dichroic organic dye are used as the dichroic dye. Examples of dichroic organic dyes include azo dyes and the like. Examples of azo dyes include C. I. Included are dichroic direct dyes made of disazo compounds such as DIRECT RED 39, and dichroic direct dyes made of compounds such as trisazo and tetrakisazo.

The base film may be provided with an alignment film on one side. From the viewpoint of improving flexibility, the polarizing film 17 is preferably a layer containing a cured product of a composition containing a polymerizable liquid crystal compound and one or more azo dyes, and an alignment film. The thickness of the alignment film may be, for example, 5 nm or more and 1 μm or less.

The polarizing film 17 may be incorporated into the laminate together with the base film as long as the cured liquid crystal layer containing a cured product of a polymerizable liquid crystal compound is incorporated into the laminate. The material and thickness of the base film may be the same as those of the thermoplastic resin film described below. A hard coat layer (HC layer) may be formed on at least one surface of the base film as a protective layer to be described later.

The thickness of the liquid crystal cured layer containing the cured product of the polymerizable liquid crystal compound is usually 10 μm or less, preferably 8 μm or less, and more preferably 5 μm or less.

[Protective layer]
The protective layer can be placed on one or both sides of the polarizing film 17 and have the function of protecting the surface of the polarizing film 17. In this specification, a polarizing film on which a protective layer is laminated may be referred to as a polarizing plate.

The protective layer can be an organic layer or an inorganic layer. The organic layer or the inorganic layer can be a layer formed by coating. The organic layer may be a cured resin layer made of a composition for forming a protective layer, such as a (meth)acrylic resin composition, an epoxy resin composition, or a polyimide resin composition. The composition for forming a protective layer may be of an active energy ray curable type or a thermosetting type. The inorganic layer can be formed from, for example, silicon oxide. When the protective layer is an organic layer, the protective layer may be called a hard coat layer (HC layer) or an overcoat (OC) layer. The protective layer may be formed directly on the above-mentioned base film, or may be formed directly on the polarizing film. After a protective layer is formed on the above-mentioned base film, a polarizing film can be formed.

When the protective layer is an organic layer, the protective layer can be prepared, for example, by applying an active energy ray-curable composition for forming a protective layer onto a base film and curing it by irradiating active energy. The above description of the base film applies to the base film. The protective layer can be incorporated into the laminate with the base film peeled and removed. Examples of the method for applying the composition for forming a protective layer include a spin coating method. When the protective layer is an inorganic layer, the protective layer can be formed by, for example, a sputtering method, a vapor deposition method, or the like. When 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 having excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, stretchability, etc. can also be used. Specific examples of such thermoplastic resins include cellulose resins such as triacetylcellulose; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyethersulfone resins; polysulfone resins; polycarbonate resins; polyamides such as nylon and aromatic polyamides. Resin; Polyimide resin; Polyolefin resin such as polyethylene, polypropylene, and ethylene-propylene copolymer; Cyclic polyolefin resin having cyclo- and norbornene structures (also referred to as norbornene-based resin); (meth)acrylic resin; Polyarylate resin; Polystyrene resin ; Polyvinyl alcohol resins and mixtures thereof can be mentioned. When protective layers are laminated on both sides of the polarizing film 17, the two protective layers may be of the same type or of different types. From the viewpoint of thinning, the thickness of the thermoplastic resin film is usually 300 μm or less, preferably 200 μm or less, more preferably 100 μm or less, still more preferably 50 μm or less, and even more preferably 30 μm or less. Moreover, it is usually 1 μm or more, and may be, for example, 5 μm or more or 20 μm or more.

When the protective layer is a thermoplastic resin film, the thermoplastic resin film can be laminated to the polarizing film 17 via a bonding layer described below. The bonding layer for bonding the thermoplastic resin film to the polarizing film 17 is preferably an adhesive layer. Alternatively, a polarizing layer may be formed on the protective layer. The laminate 100 preferably includes at least one protective layer selected from the group consisting of a thermoplastic resin film and a cured resin layer on the opposite side of the polarizing film 17 from the adhesive layer 11.

[Other layers]
(Retardation plate)
The laminate 100 may have a retardation plate on the opposite side of the polarizing plate 12 from the adhesive layer 11 via a bonding layer to be described later. The retardation plate can include a cured layer of a polymerizable liquid crystal compound. A cured layer of a polymerizable liquid crystal compound can be formed by applying a composition for forming a retardation layer containing a polymerizable liquid crystal compound to a base film and curing the composition. Examples of the application method include a coating method and a printing method. Coating methods include bar coating, knife coating, blade coating, die coating, direct gravure coating, reverse gravure coating, roll coating, CAP coating, spin coating, spray coating, screen coating, Examples include slit coating method and dip coating method. Examples of printing methods include offset printing, gravure printing, screen printing, and inkjet printing.

The cured layer of the polymerizable liquid crystal compound can be a retardation layer. The retardation layer can be composed of one layer or two or more layers. The retardation layer may be a positive A plate such as a λ/4 plate or a λ/2 plate, and a positive C plate. When the retardation plate includes only one cured layer of a polymerizable liquid crystal compound, the retardation layer is preferably a λ/4 plate. When the retardation plate includes two cured layers of polymerizable liquid crystal compounds, the retardation layer can be a retardation layer laminate including a first liquid crystal cured retardation layer and a second liquid crystal cured retardation layer. . The first liquid crystal cured retardation layer and the second liquid crystal cured retardation layer may be laminated via a bonding layer, which will be described later, and preferably are laminated via an adhesive layer. As for the combination of the first liquid crystal cured retardation layer and the second liquid crystal cured retardation layer, preferably the first liquid crystal cured retardation layer is a λ/4 plate, and the second liquid crystal cured retardation layer is a λ/2 plate. A combination in which the first liquid crystal cured retardation layer is a λ/4 plate and a second liquid crystal cured retardation layer is a positive C plate. In this specification, a polarizing plate on which a retardation layer is laminated may be referred to as a circularly polarizing plate.

The thickness of the cured layer of the polymerizable liquid crystal compound 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. A retardation layer formed by curing a polymerizable liquid crystal compound may be incorporated into the laminate 100 together with either or both of the alignment layer and the base film. The thickness of the alignment layer may be, for example, 5 nm or more and 1 μm or less.

(Lamination layer)
The bonding layer is a layer composed of a pressure-sensitive adhesive or an adhesive. The bonding layer includes, for example, a layer for bonding a polarizing film and a retardation plate, a layer for bonding a laminate and an organic EL panel or a touch sensor panel, a layer for bonding a polarizing film and a protective layer, and a layer for bonding a polarizing film and a protective layer. It can be a layer that joins the cured retardation layer and the second liquid crystal cured retardation layer. The adhesive constituting the bonding layer may be the same as that exemplified for the adhesive composition constituting the above-mentioned adhesive layer, or may be another adhesive such as a (meth)acrylic adhesive, It may be a styrene adhesive, a silicone adhesive, a rubber adhesive, a urethane adhesive, a polyester adhesive, an epoxy copolymer adhesive, or the like. The laminate 100 may include one bonding layer, or may include two or more bonding layers. When the laminate 100 includes a plurality of bonding layers, the plurality of bonding layers may be the same or different.

The adhesive constituting the bonding layer can be formed by, for example, one or a combination of two or more of water-based adhesives, active energy ray-curable adhesives, pressure-sensitive adhesives, and the like. Examples of water-based adhesives include polyvinyl alcohol resin aqueous solutions, water-based two-component urethane emulsion adhesives, and the like. Active energy ray-curable adhesives are adhesives that are cured by irradiation with active energy rays such as ultraviolet rays, such as those containing a polymerizable compound and a photopolymerization initiator, those containing a photoreactive resin, Examples include those containing a binder resin and a photoreactive crosslinking agent. 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. Examples of the photopolymerization initiator include those containing substances that generate active species such as neutral radicals, anion radicals, and cation radicals upon irradiation with active energy rays such as ultraviolet rays.

When using an adhesive layer as a bonding layer, the thickness is preferably 1 μm or more, may be 5 μm or more, and is usually 200 μm or less, for example, 150 μm or less or 100 μm or less. When using an adhesive layer as a 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 5 μm or less. There may be.

(Organic EL panel)
A known organic EL panel can be used as the organic EL panel. The laminate 100 can include an organic EL panel on the opposite side of the polarizing plate 12 from the adhesive layer 11 . When the laminate 100 has a retardation plate on the side of the adhesive layer 11 opposite to the polarizing plate 12, the organic EL panel can be arranged on the side of the retardation plate opposite to the polarizing plate 12. .

(touch sensor panel)
The detection method of the touch sensor panel is not limited as long as it is a sensor that can detect the touched position, and includes resistive film method, capacitance method, optical sensor method, ultrasonic method, electromagnetic inductive coupling method, A surface acoustic wave type touch sensor panel is exemplified. Among these, a capacitive touch sensor panel is preferably used in terms of low cost, fast reaction speed, and thin film. The touch sensor panel may include an adhesive layer, a separation layer, a protective layer, etc. between the transparent conductive layer and the base film that supports it. Examples of the adhesive layer include an adhesive layer and a pressure-sensitive adhesive layer. Examples of the base film that supports the transparent conductive layer include a base film on which a transparent conductive layer is deposited on one surface, a base film on which a transparent conductive layer is transferred via an adhesive layer, and the like.

An example of a capacitive touch sensor panel includes a base film, a transparent conductive layer for position detection provided on the surface of the base film, and a touch position detection circuit. In an image display device equipped with a laminate having a capacitive touch sensor panel, when the surface of the front panel is touched, the transparent conductive layer is grounded at the touched point via the capacitance of the human body. Ru. A touch position detection circuit detects grounding of the transparent conductive layer, and the touched position is detected. By having a plurality of transparent conductive layers spaced apart from each other, more detailed position detection becomes possible.

The transparent conductive layer may be a transparent conductive layer made of a metal oxide such as ITO, or may be a metal layer made of 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. A negative type photosensitive resist or a positive type photosensitive resist is used as the photosensitive resist, and the photosensitive resist may remain after patterning or may be removed. When forming a film by a sputtering method, an electrode pattern layer can also be formed by arranging a mask having an electrode pattern shape and performing sputtering.

The separation layer can be a layer formed on a substrate such as glass to separate a transparent conductive layer formed on the separation layer from the substrate together with the separation layer. The separation layer is preferably an inorganic layer or an organic layer. Examples of the material for forming the inorganic layer include silicon oxide. As the material for forming the organic layer, for example, a (meth)acrylic resin composition, an epoxy resin composition, a polyimide resin composition, etc. can be used. The separation layer can be formed by coating by a known coating method and curing by heat curing, UV curing, or a combination thereof.

The protective layer can be provided in contact with the transparent conductive layer to protect the conductive layer. The protective layer includes 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 a spin coating method, a sputtering method, or a vapor deposition method.

The insulating layer can be formed of, for example, an inorganic insulating material such as silicon oxide, or a transparent organic material such as acrylic resin. The insulating layer can be formed by coating using a known coating method, followed by heat curing, UV curing, heat drying, vacuum drying, or the like.

Base films for touch sensor panels include triacetylcellulose, polyethylene terephthalate, cycloolefin polymer, polyethylene naphthalate, polyolefin, polycycloolefin, polycarbonate, polyethersulfone, polyarylate, polyimide, polyamide, polystyrene, polynorbornene, etc. Examples include resin films. Polyethylene terephthalate is preferably used from the viewpoint of easy construction of a base film having desired toughness.

The base film of the touch sensor panel preferably has a thickness of 50 μm or less, more preferably 30 μm or less, from the viewpoint of easily forming 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.

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

In the second method, a material for forming a separation layer is first applied onto a substrate to form a separation layer. If necessary, a protective layer is formed on the separation layer by coating. A protective layer may be formed so that the protective layer is not formed in the portion where the pad pattern layer is formed. A transparent conductive layer patterned by photolithography is formed on the separation layer (or protective layer). An insulating layer is formed on the transparent conductive layer so as to fill the electrode pattern layer. A protective film is laminated on the insulating layer using a peelable adhesive, and the layers from the insulating layer to the separation layer are transferred to separate the substrates. By peeling off the peelable protective film, a touch sensor panel having an insulating layer/transparent conductive layer/(protective layer)/separation layer in this order is obtained.

When including the base film, the thickness of the touch sensor panel may be, for example, 5 μm or more and 2000 μm or less, or 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, and preferably 5 μm or less.

When the laminate 100 includes a touch sensor panel, the touch sensor panel can be arranged, for example, between the retardation plate and the organic EL panel, or between the front plate 10 and the polarizing plate 12.

[Layer configuration of laminate]
In the laminate 200 shown in FIG. 2, a front plate 21, an adhesive layer 22, a polarizing plate 23, a bonding layer 24, and a retardation plate 25 are laminated in this order from the viewing side. The front plate 21 has a first hard coat layer 26, a second hard coat layer 27, and an ultra-thin glass 28 laminated in this order from the viewing side. In the polarizing film 23, a base film 29, an alignment film 30, a polarizing film 31, and a protective layer 32 are laminated in this order from the viewing side. In the retardation plate 25, a first liquid crystal cured retardation layer 33 and a second liquid crystal cured retardation layer 34 are laminated in this order from the viewing side.

FIG. 3 shows the layer structure of the laminate 300. The description of each layer in FIG. 3 applies to the layer labeled with the same reference numeral in FIG. 2. The laminate 300 has the same layer structure as the laminate 200 described above, except that the first hard coat layer 26, the ultra-thin glass 28, and the second hard coat layer 27 are laminated in this order.

[Applications of laminate]
The laminate 100 can be used, for example, in an image display device. The image display device is not particularly limited, and includes, for example, an organic electroluminescent (organic EL) display device, an inorganic electroluminescent (inorganic EL) display device, a liquid crystal display device, an electroluminescent display device, and the like. The image display device may have a touch panel function. The image display device may preferably be a flexible display. The laminate 100 may be arranged in the image display device so that the front plate 10 side is the viewing side with respect to the adhesive layer 11, and preferably it is arranged so that the front plate 11 forms the outermost surface of the image display device. .

[Method for manufacturing laminate]
The laminate can be manufactured by a method including a step of laminating the layers constituting the laminate through an adhesive layer or an additional adhesive layer. When laminating layers through an adhesive layer or an adhesive layer, surface activation treatment such as corona treatment should be applied to one or both of the laminating surfaces in order to increase adhesion. is preferred.

A cured liquid crystal layer containing a cured product of a polymerizable liquid crystal compound constituting a polarizing film can be formed on a substrate via an alignment film. A liquid crystal cured layer containing a cured product of a polymerizable liquid crystal compound can be formed by applying and curing a composition for forming a liquid crystal cured layer containing a dichroic dye and a polymerizable liquid crystal compound. In addition to the above-mentioned dichroic dye and polymerizable liquid crystal compound, the composition for forming a liquid crystal cured layer preferably further contains a polymerization initiator, a leveling agent, a solvent, and a photosensitizer, a polymerization inhibitor, a leveling agent, etc. It may further include.

The retardation layer included in the retardation plate is formed by applying a retardation layer forming composition containing a polymerizable liquid crystal compound onto a base material and an alignment film if present, and polymerizing the polymerizable liquid crystal compound. can be manufactured. The composition for forming a retardation layer further contains a solvent, a polymerization initiator, and may further contain a photosensitizer, a polymerization inhibitor, a leveling agent, and the like. The base material and the alignment film may be incorporated into the retardation plate, or may be separated from the retardation plate and not become constituent elements of the laminate.

Coating and drying of the liquid crystal cured layer forming composition and retardation layer forming composition and polymerization of the polymerizable liquid crystal compound can be performed by conventionally known coating methods, drying methods, and polymerization methods.

For example, as a method for applying the composition for forming a liquid crystal cured layer and the composition for forming a retardation layer, a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a die coating method, etc. may be employed. I can do it.

The method for polymerizing the polymerizable liquid crystal compound may be selected depending on the type of polymerizable group of the polymerizable liquid crystal compound. If the polymerizable group is a photopolymerizable group, it can be polymerized by a photopolymerization method. If the polymerizable group is a thermally polymerizable group, it can be polymerized by a thermal polymerization method. In the manufacturing method of this embodiment, a photopolymerization method is preferred. Since the photopolymerization method does not necessarily require heating the transparent substrate to a high temperature, a transparent substrate with low heat resistance can be used. The photopolymerization method is carried out by irradiating visible light or ultraviolet light onto a film made of a composition for forming a liquid crystal cured layer or a composition for forming a retardation layer containing a polymerizable liquid crystal compound. Ultraviolet light is preferred because it is easy to handle.

The adhesive layer can be prepared as an adhesive sheet. Adhesive sheets are made by dissolving or dispersing an adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare an adhesive liquid, and applying this to a release film that has been subjected to a release process as a layer made of the adhesive. It can be produced by, for example, forming a sheet into a sheet and then laminating another release film on the pressure-sensitive adhesive layer. Each layer can be bonded by a method in which a pressure-sensitive adhesive sheet with one release film peeled off is bonded to one layer, then the other release film is peeled off, and the other layer is bonded.

Conventional coating techniques such as die coater, comma coater, reverse roll coater, gravure coater, rod coater, wire bar coater, doctor blade coater, air doctor coater, etc. can be used to apply the adhesive liquid onto the release film. should be adopted.

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 film, polybutylene terephthalate film, and polyethylene naphthalate film, and polyolefin films such as polypropylene film. Further, the release layer can be formed from, for example, a composition for forming a release layer. The main components (resins) constituting the composition for forming a release layer include, but are not particularly limited to, silicone resins, alkyd resins, acrylic resins, long-chain alkyl resins, and the like.

The thickness of each adhesive layer can be adjusted depending on the coating conditions of the adhesive liquid. In order to reduce the thickness of the adhesive layer, it is effective to reduce the coating thickness.

<Image display device>
An image display device according to another aspect of the present invention includes the above-described 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 that is flexible and can be bent or folded.

In the image display device, the laminate is placed on the viewing side of the display element included in the image display device, with the front plate facing outward (the side opposite to the display element side, that is, the viewing side).

Image display devices can be used as mobile devices such as smartphones and tablets, televisions, digital photo frames, electronic signboards, measuring instruments and instruments, office equipment, medical equipment, computer equipment, and the like. The image display device has excellent screen visibility because the distortion of the reflected image reflected on the front plate surface is suppressed.

Hereinafter, the present invention will be explained in more detail with reference to Examples. "%" and "parts" in the examples are mass % and parts by mass unless otherwise specified.

[Measurement of thickness]
The thicknesses of the ultra-thin glass, adhesive layer, and resin film were measured using a contact film thickness measuring device ("MS-5C" manufactured by Nikon Corporation). The polarizer layer and alignment film were measured using a laser microscope ("OLS4100" manufactured by Olympus Corporation).

[Measurement of storage modulus at a temperature of 25°C]
The storage modulus of the adhesive layer at a temperature of 25° C. was measured using a viscoelasticity measuring device (“MCR-301” (trade name) manufactured by Anton Paar). The adhesive layer was cut to a width of 20 mm x length of 20 mm, a plurality of sheets were laminated to a thickness of 150 μm, and the laminated adhesive layer was bonded to a glass plate. With the adhesive layer and the measurement chip adhered, measurements were performed in the temperature range from -20°C to 100°C under the conditions of a frequency of 1.0Hz, a deformation amount of 1%, and a temperature increase rate of 5°C/min. Storage modulus values at °C were measured.

[Evaluation of ease of handling]
After peeling off the release film from the laminate with an adhesive layer to expose the adhesive layer, apply the adhesive layer to the polarizing film of the laminate with the retardation plate side exposed to the base material (PAI film). It was pasted together. Thereafter, the laminate was visually observed to confirm the presence or absence of cracks. Ten samples were evaluated for each example and comparative example. The judgment criteria are as follows.
◎: Cracks occurred in 0 to 2 samples.
○: Cracks occurred in 3 to 4 samples.
×: Cracks occurred in 5 to 10 samples.

[Flexibility evaluation]
The release film was peeled off from the adhesive layer-attached laminate to expose the adhesive layer. Next, the side of the retardation plate of the adhesive layer-attached laminate opposite to the polarizing plate was bonded to a base material (PAI film) via the adhesive layer. A bending evaluation equipment (manufactured by Yuasa System, planar no-load U-shaped stretch test: DLDMLH-FS) was used. FIG. 4 is a diagram schematically showing the method of this evaluation test. As shown in FIG. 4, two individually movable mounting tables 401 and 402 are arranged with a gap C of 3.0 mm (bending radius 1.5 mm), and the widthwise center is placed at the center of the gap C. The laminated body 400 was fixed and arranged so that it was located (FIG. 4(a)). At this time, the laminate 400 was arranged with the front plate facing upward. Then, the two mounting tables 401 and 402 were rotated 90 degrees upwards with the positions P1 and P2 as the center of the rotation axis, and a bending force was applied to the area of the stacked body 400 corresponding to the gap C of the mounting tables ( Figure 4(b)). Thereafter, the two mounting tables 401 and 402 were returned to their original positions (FIG. 4(a)). After completing the above series of operations, the number of times the bending force was applied was counted as one. After repeating this at room temperature, it was confirmed whether or not cracks were generated in the area corresponding to the gap C between the mounting tables 401 and 402 of the laminate 400. The moving speed of the mounting tables 401 and 402 and the pace of application of the bending force were kept the same in the evaluation tests for all laminates. The criteria for counting the number of bending times at which cracks occur in each laminate after bending each laminate are as follows.
○: No cracks were generated even after 200,000 bends.
×: Cracks occur when the number of bends is less than 200,000 times.

(Preparation of hard coat layer forming composition 1)
2.0 parts by mass of dendrimer acrylate having an 18-functional acrylic group (Miramer SP1106, manufactured by Miwon Specialty Chemical), urethane acrylate having a 6-functional acrylic group (Miramer PU-620D, manufactured by Miwon Specialty Chemical) 10.0 parts by mass , 8 parts by mass of an acrylate monomer having a trifunctional acrylic group (M340, manufactured by Miwon Specialty Chemical), 2 parts by mass of a photopolymerization initiator (Irgacure (registered trademark) 184, manufactured by BASF), and a leveling agent (BYK-UV3530, BYK Chemie) 0.1 part by mass (manufactured by Japan Co., Ltd.) was dissolved in 70 parts by mass of methyl ethyl ketone (MEK) and mixed with stirring to obtain Composition 1 for Forming a Hard Coat Layer.

(Preparation of hard coat layer forming composition 2)
30 parts by mass of polyfunctional acrylate (Miramer M340, manufactured by Miwon Specialty Chemical), 50 parts by mass of propylene glycol monomethyl ether dispersion of nanosilica sol (12 nm, solid content 40%), 17 parts by mass of ethyl acetate, and a photopolymerization initiator. 2.7 parts by mass of Irgacure-184 (manufactured by Ciba Corporation) and 0.3 parts by mass of a fluorine additive (KY1203, manufactured by Shin-Etsu Chemical Co., Ltd.) were stirred and mixed to form Hard Coat Layer Forming Composition 2. Obtained.

(Preparation of front plate A)
Hard coat layer forming composition 2 was applied to one side of ultra-thin glass 1 (thickness: 50 μm) (UTG1), the resulting coating film was dried at a temperature of 80°C for 5 minutes, and then exposed to UV irradiation equipment (SPOTCURE). A hard coat layer 2 (HC layer 2) was formed by irradiating UV light with an exposure amount of 500 mJ/cm ² (365 nm standard) using a UV light source (SP-7, manufactured by Ushio Inc.). The coating was applied so that the thickness after curing was 10 μm. A front plate A having a layer structure of HC layer 2 (thickness 10 μm)/UTG1 (thickness 50 μm) was obtained.

(Preparation of front plate B)
A layer of HC layer 2 (thickness 10 μm)/UTG2 (thickness 30 μm) was prepared in the same manner as in the production of front panel A, except that UTG1 was changed to ultra-thin glass 2 (thickness 30 μm) (UTG2). A front plate B having the following structure was obtained.

(Preparation of front plate C)
Hard coat layer forming composition 1 was applied to one side of UTG1, the resulting coating film was dried at a temperature of 80°C for 5 minutes, and a UV irradiation device (SPOTCURE SP-7, manufactured by Ushio Inc.) was applied. A hard coat layer 1 (HC layer 1) was formed by irradiating UV light with an exposure amount of 500 mJ/cm ² (based on 365 nm). The coating was applied so that the thickness after curing was 10 μm. Then, in the same manner, the HC layer 2 was formed on the HC layer 1 using the composition 2 for forming a hard coat layer so that the thickness after curing was 10 μm. In the manner described above, a front plate C having a layer structure of HC layer 2 (thickness 10 μm)/HC layer 1 (thickness 10 μm)/UTG1 (thickness 50 μm) was obtained.

(Preparation of front plate D)
In the production of front plate C, the layer structure of HC layer 2 (thickness 10 μm)/HC layer 1 (thickness 10 μm)/UTG2 (thickness 30 μm) was prepared in the same manner as in the production of front plate A except that UTG1 was changed to UTG2. A front plate D having the following properties was obtained.

(Preparation of front plate E)
Hard coat layer forming composition 1 was applied to one side of UTG2, the resulting coating film was dried at a temperature of 80°C for 5 minutes, and a UV irradiation device (SPOTCURE SP-7, manufactured by Ushio Inc.) was applied. The HC layer 1 was formed by irradiating UV light with an exposure amount of 500 mJ/cm ² (based on 365 nm). The coating was applied so that the thickness after curing was 10 μm. Then, in the same manner, the HC layer 2 was formed on the other side of the UTG 2 using the composition 2 for forming a hard coat layer so that the thickness after curing would be 10 μm. In the manner described above, a front plate E having the layer structure of HC layer 2 (thickness: 10 μm)/UTG2 (thickness: 30 μm)/HC layer 1 (thickness: 10 μm) was obtained.

(Preparation of adhesive sheet)
Adhesive compositions A, B, and C were prepared to form adhesive layers A, B, and C, respectively, using the proportions of each component shown in Table 1 below. Using an applicator, apply these adhesive compositions A, B, and C onto the release-treated surface of a release film (polyethylene terephthalate film, thickness 38 μm) so that the thickness after drying becomes 25 μm. Coated. The coating layer was dried at 100° C. for 1 minute to obtain a film including adhesive layers A, B, and C. Thereafter, another release film (polyethylene terephthalate film, thickness 38 μm) that had been subjected to release treatment was laminated on the adhesive layers A, B, and C. Thereafter, the adhesive sheets A, B, and C were obtained by curing for 7 days at a temperature of 23° C. and a relative humidity of 50% RH. Furthermore, a pressure-sensitive adhesive sheet D having a pressure-sensitive adhesive layer D having a thickness of 5 μm was produced using the pressure-sensitive adhesive composition C according to the same procedure.

The symbols in the monomer column in Table 1 have the following meanings.
BA: Butyl acrylate MMA: Methyl acrylate EHA: 2-ethylhexyl acrylate AA: Acrylic acid

The following crosslinking agents and silane coupling agents in Table 1 were used.
Crosslinking agent: Coronate L (manufactured by Tosoh Corporation)
Silane coupling agent: KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd.)

[Preparation of polarizing plate A]
(Base film)
A triacetyl cellulose (TAC) film (manufactured by Konica Minolta, Inc., thickness 25 μm) was prepared as a base film.

ＧＰＣ測定より、得られたポリマー１の分子量は数平均分子量２８２００、Ｍｗ／Ｍｎ１．８２を示し、モノマー含有量は０．５％であった。
ポリマー１を濃度５質量％で、シクロペンタノンに溶解した溶液を配向膜形成用組成物として用いた。 (Composition for forming alignment film)
Polymer 1 is a polymer having a photoreactive group consisting of the following structural units.

From GPC measurement, the molecular weight of the obtained polymer 1 was 28,200, Mw/Mn was 1.82, and the monomer content was 0.5%.
A solution in which Polymer 1 was dissolved in cyclopentanone at a concentration of 5% by mass was used as a composition for forming an alignment film.

(Polymerizable liquid crystal compound)
The polymerizable liquid crystal compound includes a polymerizable liquid crystal compound represented by formula (1-6) [hereinafter also referred to as compound (1-6)] and a polymerizable liquid crystal compound represented by formula (1-7) [hereinafter referred to as compound (1-6)]. Also referred to as compound (1-7)] was used.

Compound (1-6) and compound (1-7) were prepared by Lub et al. Recl. Trav. Chim. It was synthesized by the method described in Pays-Bas, 115, 321-328 (1996).

(dichroic dye)
As the dichroic dye, azo dyes described in Examples of JP-A No. 2013-101328, which are represented by the following formulas (2-1a), (2-1b), and (2-3a), were used.

(Composition for forming a liquid crystal cured layer)
The composition for forming a liquid crystal cured layer contains 75 parts by mass of compound (1-6), 25 parts by mass of compound (1-7), and the above formulas (2-1a), (2-1b), ( 2.5 parts by mass of each azo dye represented by 2-3a), 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 with 400 parts by mass of toluene as a solvent, and the resulting mixture was heated at 80°C to 1.2 parts by mass. Prepared by stirring for hours.

(Composition for protective layer (OC layer))
The composition for the protective layer contains 100 parts by mass of water, 3 parts by mass of polyvinyl alcohol resin powder (manufactured by Kuraray Co., Ltd., average degree of polymerization 18,000, trade name: KL-318) and polyamide epoxy resin (crosslinking agent, It was prepared by mixing 1.5 parts by mass of SR650 (30) manufactured by Kachemtex Corporation.

(Preparation of polarizing film)
The base film was subjected to corona treatment. The conditions for the corona treatment were an output of 0.3 kW and a treatment speed of 3 m/min. Thereafter, the composition for forming an alignment film was applied onto the base film by a bar coating method, and dried by heating in a drying oven at 80° C. for 1 minute. The obtained dried film was subjected to polarized UV irradiation treatment to form an alignment film. Polarized UV treatment is performed by transmitting light emitted from a UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Inc.) through a wire grid (UIS-27132##, manufactured by Ushio Inc.) at a wavelength of 365 nm. The measurement was carried out under the condition that the cumulative light amount measured in 1 was 100 mJ/cm ² . The thickness of the alignment film was 100 nm.

A composition for forming a liquid crystal cured layer was applied onto the formed alignment film by a bar coating method, dried by heating in a drying oven at 120° C. for 1 minute, and then cooled to room temperature. A liquid crystal cured layer (polarizing film) was formed by irradiating the dry film with ultraviolet rays at a cumulative light amount of 1200 mJ/cm ² (365 nm standard) using the above UV irradiation device. The thickness of the obtained liquid crystal cured layer was measured using a laser microscope (OLS3000 manufactured by Olympus Corporation) and was found to be 1.8 μm. In this way, a laminated film A having a layer structure of base film/alignment film/cured liquid crystal layer was obtained.

On the formed liquid crystal cured layer, a composition for a protective layer (OC layer) was applied by a bar coating method so that the thickness after drying was 1.0 μm, and dried at a temperature of 80° C. for 3 minutes. In this way, a polarizing plate A consisting of a base film/alignment film/cured liquid crystal layer/protective layer (OC layer) was obtained.

[Preparation of polarizing plate B]
(protective layer)
As a protective layer, a cycloolefin polymer (COP) film (ZF-14, manufactured by Nippon Zeon Co., Ltd., thickness 23 μm) was prepared.

(polarizing film)
A long polyvinyl alcohol (PVA) raw film with a thickness of 30 μm [trade name “Kuraray Poval Film VF-PE #3000” manufactured by Kuraray Co., Ltd., average degree of polymerization 2400, degree of saponification 99.9 mol% or more] was rolled. The sample was continuously conveyed while being unwound from the plate, and immersed in a swelling bath consisting of pure water at 20°C for a residence time of 31 seconds (swelling step). Thereafter, the film pulled out from the swelling bath was immersed in a 30° C. dyeing bath containing iodine with a potassium iodide/water ratio of 2/100 (weight ratio) for a residence time of 122 seconds (dying step). Next, the film pulled out from the dyeing bath was immersed in a crosslinking bath at 56°C containing potassium iodide/boric acid/water at a ratio of 12/4.1/100 (weight ratio) for a residence time of 70 seconds, and then The sample was immersed in a 40° C. crosslinking bath containing potassium chloride/boric acid/water at a ratio of 9/2.9/100 (weight ratio) for a residence time of 13 seconds (crosslinking step). In the dyeing process and the crosslinking process, longitudinal uniaxial stretching was performed by stretching between rolls in a bath. The total stretching ratio based on the original film was 5.4 times. Next, the film pulled out from the crosslinking bath is immersed in a cleaning bath made of pure water at 5° C. for a residence time of 3 seconds (cleaning step), and then subsequently introduced into a first heating furnace where humidity can be adjusted. A high-temperature, high-humidity treatment was performed with a residence time of 190 seconds (high-temperature, high-humidity treatment step) to obtain a polarizing film (PVA) with a thickness of 12.1 μm.

(Adhesive composition)
Water: 100 parts by weight, polyvinyl alcohol resin powder (manufactured by Kuraray Co., Ltd., average degree of polymerization 18,000, product name: KL-318): 3 parts by weight, polyamide epoxy resin (crosslinking agent, manufactured by Sumika Chemtex Co., Ltd., product name: SR650 (30): 1.5 parts by weight were mixed to obtain an adhesive composition.

Corona treatment was applied to the polarizing film and protective layer. The conditions for the corona treatment were an output of 0.3 kW and a treatment speed of 3 m/min. Thereafter, these were bonded together via an adhesive composition and dried at 60° C. for 2 minutes to obtain a polarizing plate B consisting of a protective layer/polarizer layer.

[Fabrication of retardation plate]
(First liquid crystal hardened retardation layer)
As the first liquid crystal cured retardation layer, a layer providing a λ/4 retardation consisting of a layer in which a nematic liquid crystal compound was cured, an alignment layer, and a transparent base material was prepared. Note that the total thickness of the layer in which the nematic liquid crystal compound was cured and the alignment layer was 2 μm. The layer in which the nematic liquid crystal compound was cured was formed by applying a composition for forming a retardation layer containing the nematic liquid crystal compound onto the alignment layer formed on the base film (transparent base material) and curing the composition.

(Second liquid crystal hardened retardation layer)
A polyethylene terephthalate base material with a thickness of 38 μm was used as a base film (transparent base material), one side of which was coated with a composition for a vertical alignment layer to a thickness of 3 μm, and irradiated with polarized ultraviolet rays of 20 mJ/cm ² . An alignment layer was prepared. The composition for the vertical alignment layer includes 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, dipentaerythritol triacrylate, and bis(2-vinyloxyethyl) ether in a ratio of 1:1:4:5. A mixture was used in which LUCIRIN (registered trademark) TPO was added as a polymerization initiator at a ratio of 4%.

Next, a composition for forming a retardation layer containing a photopolymerizable nematic liquid crystal (manufactured by Merck & Co., Ltd., RMM28B) was applied onto the formed alignment layer by die coating. Here, in the liquid crystal composition, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone (CHN) having a boiling point of 155° C. are used as solvents in a mass ratio (MEK:MIBK:CHN) of 35: A mixed solvent mixed at a ratio of 30:35 was used. Then, a retardation layer forming composition prepared to have a solid content of 1 to 1.5 g was coated on the alignment layer in a coating amount of 4 to 5 g (wet).

After coating the composition for forming a retardation layer on the alignment layer, a drying treatment was performed at a drying temperature of 75° C. and a drying time of 120 seconds. Thereafter, the liquid crystal compound was polymerized by ultraviolet (UV) irradiation to obtain a positive C layer consisting of a layer in which the photopolymerizable nematic liquid crystal compound was cured, an alignment layer, and a transparent base material. The total thickness of the layer in which the photopolymerizable nematic liquid crystal compound was cured and the alignment layer was 4 μm.

(Preparation of retardation plate)
The first liquid crystal cured retardation layer and the second liquid crystal cured retardation layer are bonded using an ultraviolet curable adhesive so that the surface of each liquid crystal cured retardation layer (the surface opposite to the transparent base material) becomes the bonding surface. pasted on. Next, the ultraviolet curable adhesive was cured by irradiation with ultraviolet rays. The thickness of the ultraviolet curable adhesive after curing was 2 μm. In this way, the base film/alignment layer/first liquid crystal cured retardation layer (2 μm)/adhesive layer (thickness 2 μm)/second liquid crystal cured retardation layer (thickness 4 μm)/alignment layer/base film A retardation plate having a layered structure was manufactured.

<Example 1>
The adhesive layer D, which was exposed by peeling one release film from the adhesive sheet D, was bonded to the protective layer side of the polarizing plate A to obtain a laminate A1. Both surfaces to be bonded were previously subjected to double-sided corona treatment (output: 0.3 kW, speed: 3 m/min).

The base film on the first liquid crystal cured retardation layer side of the retardation plate was peeled off, and the other release film was peeled off from the laminate A1 to expose the adhesive layer D. Furthermore, the adhesive layer D of the laminate A1 and the first liquid crystal cured retardation layer of the retardation plate were bonded together to obtain a laminate A2. Both surfaces to be bonded were previously subjected to double-sided corona treatment (output: 0.3 kW, speed: 3 m/min).

One release film was peeled off from adhesive sheet A to expose adhesive layer A. Next, the exposed adhesive layer A was bonded to the surface of the laminate A2 from which the base film used for forming the second liquid crystal cured retardation layer was peeled off, to obtain a laminate A3. Both surfaces to be bonded were previously subjected to double-sided corona treatment (output: 0.3 kW, speed: 3 m/min).

One release film was peeled off from another adhesive sheet A (referred to as adhesive sheet A') to expose adhesive layer A (referred to as adhesive layer A'). Next, the exposed adhesive layer A' was bonded to the UTG side of the front plate to obtain a laminate A4. Both surfaces to be bonded were previously subjected to double-sided corona treatment (output: 0.3 kW, speed: 3 m/min).

The other release film was peeled off from the laminate A4 to expose the adhesive layer A'. Next, the adhesive layer A' of the laminate A4 was bonded to the base film side of the polarizing plate A of the laminate A3 to obtain a laminate with an adhesive layer. Both surfaces to be bonded were previously subjected to double-sided corona treatment (output: 0.3 kW, speed: 3 m/min). The results are shown in Table 2.

<Examples 2 to 6 and Comparative Examples 1 to 4>
The adhesive layer was prepared in the same manner as in Example 1, except that the front plate, polarizing film, and adhesive layer of the types shown in Table 1 were used as the front plate, the polarizing film, and the adhesive layer for bonding the front plate and the polarizing film. A laminate was obtained. In Example 5, the adhesive layer A was bonded to the HC layer 1 side of the front plate. Further, in Comparative Example 1 and Comparative Example 2, UTG1 and UTG2 were used as the front plate without forming a hard coat layer, respectively. Furthermore, in Comparative Example 5, an adhesive layer was directly bonded to polarizing film B. The results are shown in Table 2.

100, 200, 300, 400 laminate, 10, 21 front plate, 11, 22 adhesive layer, 12, 23 polarizing plate, 13 hard coat layer, 14, 28 ultra-thin glass, 24 laminating layer, 25 retardation plate, 26 first hard coat layer, 27 second hard coat layer, 15, 29 base film, 16, 30 alignment film, 17, 31 polarizing film (liquid crystal hardening layer), 18, 32 protective layer, 33 first liquid crystal Cured retardation layer, 34 Second liquid crystal cured retardation layer, 401, 402 Mounting table.

Claims (11)

It includes a front plate, an adhesive layer, and a polarizing film in this order,
The front plate includes ultra-thin glass and a hard coat layer,
The storage modulus of the adhesive layer at a temperature of 25° C. is 0.2 MPa or less,
The polarizing film is a laminate comprising a cured liquid crystal layer containing a cured product of a polymerizable liquid crystal compound. The laminate according to claim 1, wherein the ultra-thin glass has a thickness of 50 μm or less. The laminate according to claim 1, wherein the hard coat layer has a thickness of 10 μm or more. The laminate according to claim 2, wherein the hard coat layer has a thickness of 10 μm or more. The laminate according to any one of claims 1 to 4, wherein the adhesive layer has a storage modulus of 0.01 MPa or more at a temperature of 25°C. The laminate according to any one of claims 1 to 4, wherein the adhesive layer has a thickness of 30 μm or less. The laminate according to claim 5, wherein the adhesive layer has a thickness of 30 μm or less. An image display device comprising the laminate according to any one of claims 1 to 4. An image display device comprising the laminate according to claim 5. An image display device comprising the laminate according to claim 6. An image display device comprising the laminate according to claim 7.

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