阅读说明：本技术 层叠体和图像显示装置 (Laminate and image display device ) 是由 柳智熙 金恩瑛 金东辉 于 2020-03-04 设计创作，主要内容包括：本发明的目的在于提供一种层叠体和具备它的图像显示装置,该层叠体具备前面板和在双面具有粘合剂层的圆偏振片的可弯曲的层叠体,即使在以前面板侧为内侧并在高温高湿环境下弯曲的状态下长时间放置后,在弯折的部分,在前面板侧的表面产生的波纹也小,可视性优异。本发明提供一种层叠体,其具备前面板和带双面粘合剂层的圆偏振片,在将前面板的厚度设为a[μm]、将带双面粘合剂层的圆偏振片的厚度设为b[μm]、将前面板在温度60℃及相对湿度90％RH下的耐湿热弹性模量设为c[MPa]时,满足[(b/a)×c]≥2200。(The present invention provides a laminate having a front panel and a flexible laminate of circularly polarizing plates having adhesive layers on both sides, which is excellent in visibility and has a small waviness on the surface on the front panel side at the bent portion even after being left for a long time in a state where the front panel side is inside and bent under a high-temperature and high-humidity environment, and an image display device including the laminate. The present invention provides a laminate comprising a front panel and a circularly polarizing plate with a double-sided adhesive layer, wherein the thickness of the front panel is a [ mu ] m, the thickness of the circularly polarizing plate with the double-sided adhesive layer is b [ mu ] m, and the wet heat resistance elastic modulus of the front panel at a temperature of 60 ℃ and a relative humidity of 90% RH is c [ MPa ], and the laminate satisfies [ (b/a). times.c ]. gtoreq.2200.)

1. A laminate comprising a front panel and a circularly polarizing plate with a double-sided adhesive layer, wherein the thickness of the front panel is a [ mu ] m, the thickness of the circularly polarizing plate with a double-sided adhesive layer is b [ mu ] m, and the tensile modulus of elasticity of the front panel at a temperature of 60 ℃ and a relative humidity of 90% RH is c [ MPa ], and the laminate satisfies the following formula (1):

[(b/a)×c]≥2200 (1)。

2. the laminate according to claim 1, wherein a and c satisfy the following formula (2):

a/c≤0.03 (2)。

3. the laminate of claim 1 or 2, wherein the front panel has a hard coating.

4. The laminate according to any one of claims 1 to 3, wherein the circularly polarizing plate with a double-sided adhesive layer comprises a 1 st adhesive layer, a linearly polarizing plate, a phase difference layer and a 2 nd adhesive layer in this order.

5. The laminate according to claim 4, wherein the linearly polarizing plate comprises a thermoplastic resin film having a hard coat layer on at least one surface.

6. An image display device comprising the laminate according to any one of claims 1 to 5.

Technical Field

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

Background

Patent document 1 proposes an image display device having an image display panel, an adhesive layer, and a flexible film in this order, in which the adhesive layer is disposed in a bent region so as to be spaced apart from the image display panel.

Documents of the prior art

Patent document

Patent document 1: korean laid-open patent No. 10-2016-0069560

Disclosure of Invention

When a laminate including a front panel and a circularly polarizing plate having adhesive layers on both sides is left in a bent state in a high-temperature and high-humidity environment and then released from the bent state, ripples may be generated in the bent portion. The waviness sometimes reduces the smoothness of the surface. If the smoothness of the surface is reduced, for example, the reflected image is distorted, and visibility is reduced. The present invention provides a laminate which is a bendable laminate comprising a front panel and circularly polarizing plates having adhesive layers on both sides, and which has a small waviness on the surface of the front panel side at the bent portion and is excellent in visibility even after being left for a long time in a state where the front panel side is inside and bent under a high-temperature and high-humidity environment, and an image display device provided with the laminate.

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

[1] A laminate comprising a front panel and a circularly polarizing plate with a double-sided adhesive layer, wherein the thickness of the front panel is a [ mu ] m, the thickness of the circularly polarizing plate with a double-sided adhesive layer is b [ mu ] m, and the tensile modulus of elasticity of the front panel at a temperature of 60 ℃ and a relative humidity of 90% RH is c [ MPa ], and the laminate satisfies the following formula (1):

[(b/a)×c]≥2200 (1)

[2] the laminate according to [1], wherein a and c satisfy the following formula (2):

a/c≤0.03 (2)。

[3] the laminate according to [1] or [2], wherein the front sheet has a hard coat layer.

[4] The laminate according to any one of [1] to [3], wherein the double-sided adhesive layer-attached circularly polarizing plate comprises a 1 st adhesive layer, a linearly polarizing plate, a retardation layer and a 2 nd adhesive layer in this order.

[5] The laminate according to [4], wherein the linearly polarizing plate comprises a thermoplastic resin film having a hard coat layer on at least one surface thereof.

[6] An image display device comprising the laminate according to any one of [1] to [5 ].

According to the present invention, there can be provided a laminate which is a bendable laminate comprising a front panel and circularly polarizing plates having adhesive layers on both sides, and which has a small waviness generated on the surface on the front panel side at the bent portion and is excellent in visibility even after being left for a long time in a state where the front panel side is inside and bent under a high-temperature and high-humidity environment, and an image display device provided with the laminate.

Drawings

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

Fig. 2 is a schematic cross-sectional view showing a laminate according to another embodiment of the present invention.

Detailed Description

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

< laminate >

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 includes a front panel 10 and a circularly polarizing plate 20 with a double-sided adhesive layer.

The laminated body 100 may be bent at least in a direction in which the front panel 10 is inside. The bendable means that the panel can be bent in a direction inward of the front panel 10 without causing cracks.

The laminate 100 satisfies the following formula (1) when the thickness of the front panel 10 is a [ μm ], the thickness of the circularly polarizing plate 20 with a double-sided adhesive layer is b [ μm ], and the tensile elastic modulus of the front panel 10 at a temperature of 60 ℃ and a relative humidity of 90% RH (hereinafter, also simply referred to as "tensile elastic modulus") is c [ MPa ]. In the present specification, unless otherwise specified, the tensile elastic modulus refers to a value measured under an environment of a temperature of 60 ℃ and a relative humidity of 90% RH.

[(b/a)×c]≥2200 (1)

By satisfying the formula (1) in the laminate 100, even after the front panel 10 is placed inside and bent under a high-temperature and high-humidity environment for a long time, waviness occurring on the surface of the front panel 10 side can be suppressed in the bent portion, and uniform visibility can be ensured. The front panel 10 and the circularly polarizing plate 20 with a double-sided adhesive layer are selected so as to satisfy the above formula (1). From the viewpoint of improving the waviness of the surface, the laminate 100 preferably satisfies the following formula (1a), and more preferably satisfies the following formula (1 b).

[(b/a)×c]≥3000 (1a)

[(b/a)×c]≥4000 (1b)

The laminate 100 preferably satisfies the following formula (1 c).

[(b/a)×c]≤10000 (1c)

The present inventors have found that, after a laminate including a front panel and a circularly polarizing plate with a double-sided adhesive layer is left for a long time in a state where the front panel is inside and bent under a high-temperature and high-humidity environment, waviness occurs on the surface of the front panel side of the bent portion, and it is sometimes impossible to ensure uniform visibility. As a result of the study, it was found that the above-mentioned waviness can be suppressed by adjusting the thickness of the front panel, the thickness of the circularly polarizing plate with a double-sided adhesive layer, and the tensile elastic modulus of the front panel so that the laminate including the front panel and the circularly polarizing plate with a double-sided adhesive layer satisfies formula (1).

In the present specification, the tensile modulus is measured by the method described in the following examples.

From the viewpoint of suppressing moire, the laminate 100 preferably has a and c satisfying the following formula (2).

a/c≤0.03 (2)

From the viewpoint of suppressing the moire, the laminate 100 more preferably satisfies the following formula (2 a).

a/c≤0.02 (2a)

From the viewpoint of suppressing the moire, the laminate 100 preferably satisfies the following formula (2 b).

a/c≥0.009 (2b)

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

The thickness of the laminate 100 is not particularly limited, and is, for example, 20 to 500 μm, preferably 30 to 400 μm, and more preferably 50 to 300 μm, since it varies depending on the functions required for the laminate, the application of the laminate, and the like.

The laminate 100 can be used for, for example, a display device or the like. The display device is not particularly limited, and examples thereof include an organic electroluminescence (organic EL) display device, an inorganic electroluminescence (inorganic EL) display device, a liquid crystal display device, and an electroluminescence display device. The lamination body 100 is suppressed in waviness after bending, and is therefore suitable for a flexible display.

[ front panel ]

The front panel 10 may be a plate-shaped body that can transmit light. The front panel 10 may be composed of only 1 layer, or 2 or more layers. Examples thereof include a plate-like body made of resin (for example, a resin plate, a resin sheet, a resin film, etc.), a plate-like body made of glass (for example, a glass plate, a glass film, etc.), and the like. The front panel may be a layer constituting the outermost surface of the display device.

The thickness a [ μm ] of the front panel 10 may be, for example, 10 μm to 100 μm, preferably 20 μm to 85 μm, and more preferably 30 μm to 70 μm, from the viewpoint of suppressing waviness after bending and thinning of the laminate. In the present invention, the thickness of each layer can be measured by the thickness measurement method described in the following examples.

The front panel 10 may have a tensile elastic modulus c [ MPa ] of, for example, 1500MPa or more at a temperature of 60 ℃ and a relative humidity of 90% RH, and from the viewpoint of suppressing waviness after bending, the tensile elastic modulus c [ MPa ] is preferably 2000MPa to 20000MPa, and more preferably 2000MPa to 10000 MPa. The tensile elastic modulus can be adjusted to the above range by, for example, selecting the material and thickness of the plate-like body constituting the front panel, selecting the composition of the hard coat layer-forming composition for forming the hard coat layer described later, the thickness of the cured product thereof, and a combination thereof.

When the front panel 10 is a resin plate-like body, the resin plate-like body may be, for example, a resin film that transmits light. Examples of the thermoplastic resin constituting the plate-like body made of a resin such as a resin film include polyolefin resins such as a chain polyolefin resin (e.g., a polyethylene resin, a polypropylene resin, and a polymethylpentene resin) and a cyclic polyolefin resin (e.g., a norbornene resin); cellulose resins such as cellulose triacetate; polyester resins such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; a polycarbonate-based resin; ethylene-vinyl acetate-based resin; a polystyrene-based resin; a polyamide resin; a polyetherimide resin; (meth) acrylic resins such as polymethyl (meth) acrylate resins; a polyimide-based resin; a polyether sulfone-based resin; a polysulfone-based resin; a polyvinyl chloride resin; a polyvinylidene chloride resin; a polyvinyl alcohol resin; a polyvinyl acetal resin; a polyether ketone resin; a polyether ether ketone resin; a polyether sulfone-based resin; polyamide-imide resins, and the like. The thermoplastic resins may be used alone or in combination of 2 or more.

Among them, as the thermoplastic resin constituting the front panel, a cyclic polyolefin-based resin, a polyimide-based resin, a polyamide-based resin, and a polyamideimide-based resin are preferable, and a polyamideimide-based resin is more preferable, from the viewpoint of flexibility, strength, and transparency. Specific examples of the polyamideimide resin include polyamideimide films described in jp 2018-119141 a.

The front panel 10 may be a film provided with a hard coat layer on at least one side of a substrate film. As the base film, a film made of the above resin can be used. The hard coat layer may be formed on one surface of the substrate film or on both surfaces. By providing the hard coat layer, a resin film having improved hardness and scratch resistance can be produced.

The hard coat layer can be formed from a cured product of a hard coat layer-forming composition (hereinafter also referred to as HC layer-forming composition) containing an active energy ray-curable resin. Examples of the ultraviolet curable resin include acrylic resins, silicone resins, polyester resins, polyurethane resins, amide resins, and epoxy resins. The hard coating may also contain additives for strength. The additive is not limited, and may be inorganic fine particles, organic fine particles, or a mixture thereof. The composition for forming an HC layer can be prepared, for example, according to the method described in Korean laid-open patent No. 10-2018-0127050 and the like.

When the front panel 10 is a glass plate, a strengthened glass for display is preferably used as the glass plate. By using the glass plate, the front panel 10 having excellent mechanical strength and surface hardness can be constituted.

When the laminate 100 is used in a display device, the front panel 10 may have a function of protecting the front surface (screen) of the display device (a function as a window film), a function as an operation surface on which a touch detected by the touch sensor panel 30 is performed, a blue light cut-off function, a viewing angle adjustment function, and the like.

[ circular polarizing plate with double-sided adhesive layer ]

The circularly polarizing plate with double-sided adhesive layer 20 preferably comprises a 1 st adhesive layer, a linear polarizing plate, a retardation layer and a 2 nd adhesive layer in this order. In this embodiment, the thickness of the circularly polarizing plate with double-sided adhesive layer 20 may be the distance from the surface of the 1 st adhesive layer opposite to the linearly polarizing plate side to the surface of the 2 nd adhesive layer opposite to the linearly polarizing plate side. The circularly polarizing plate having the linear polarizing layer and the retardation layer arranged such that the absorption axis of the linear polarizing plate and the slow axis of the retardation layer form a predetermined angle can exhibit an antireflection function. In the case where the phase difference layer comprises a λ/4 plate, the angle of the absorption axis of the linearly polarizing plate with the slow axis of the λ/4 plate may be 45 ° ± 10 °. The linearly polarizing plate and the retardation layer may be bonded to each other through an adhesive layer described later. Hereinafter, the 1 st adhesive layer and the 2 nd adhesive layer may be collectively referred to as an adhesive layer.

The thickness b of the circularly polarizing plate 20 with a double-sided adhesive layer may be, for example, 10 to 200. mu.m, preferably 15 to 150. mu.m, and more preferably 20 to 100. mu.m.

(Linear polarizer)

Examples of the linearly polarizing plate include a film including a polarizer, which is a stretched film or a stretched layer having a dichroic dye adsorbed thereon, or a film obtained by coating and curing a composition including a dichroic dye and a polymerizable compound. As the dichroic dye, specifically, iodine or a dichroic organic dye is used. The dichroic organic dye includes a dichroic direct dye composed of a disazo compound such as c.i. direct red (DIRECT RED)39, and a dichroic direct dye composed of a compound such as a trisazo compound or a tetrazo compound.

Examples of the film used as a polarizer and obtained by coating and curing a composition containing a dichroic dye and a polymerizable compound include a film containing a cured product of a polymerizable liquid crystal compound, such as a layer obtained by coating and curing a composition containing a dichroic dye having liquid crystallinity or a composition containing a dichroic dye and a polymerizable liquid crystal. A film obtained by coating and curing a composition containing a dichroic dye and a polymerizable compound is preferable to a stretched film or a stretched layer having a dichroic dye adsorbed thereon because the direction of bending is not limited.

The linearly polarizing plate may be composed of only a polarizer, or may include a protective layer, a thermoplastic resin film, a substrate, an alignment film, and a protective layer, which will be described later, in addition to the polarizer. The thickness of the linearly polarizing plate is, for example, 2 μm to 100 μm, preferably 10 μm to 60 μm.

(1) Linear polarizing plate having stretched film or stretched layer as polarizer

First, a linearly polarizing plate including a stretched film having a dichroic dye adsorbed thereon as a polarizer will be described. The stretched film having a dichroic dye adsorbed thereon as a polarizer can be generally produced by the following steps: the method for producing a resin film comprises a step of uniaxially stretching a polyvinyl alcohol resin film, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol resin film with the dichroic dye, a step of treating the polyvinyl alcohol resin film adsorbed with the dichroic dye with an aqueous boric acid solution, and a step of washing the polyvinyl alcohol resin film with water after the treatment with the aqueous boric acid solution. Such a polarizer may be used as it is as a linearly polarizing plate, or a polarizer obtained by sticking a thermoplastic resin film described later on one surface or both surfaces thereof may be used as a linearly polarizing plate. The thickness of the polarizer is preferably 2 μm to 40 μm.

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

The saponification degree of the polyvinyl alcohol resin is usually 85 to 100 mol%, 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.

Next, a linearly polarizing plate including a stretched layer having a dichroic dye adsorbed thereon as a polarizer will be described. The stretched layer having a dichroic dye adsorbed thereon as a polarizer is generally produced by the following steps: the method for producing a polarizer includes a step of coating a coating liquid containing the polyvinyl alcohol resin on a base film, a step of uniaxially stretching the obtained laminated film, a step of producing a polarizer by adsorbing a dichromatic pigment by dyeing the polyvinyl alcohol resin layer of the uniaxially stretched laminated film with the dichromatic pigment, a step of treating the film adsorbed with the dichromatic pigment with an aqueous boric acid solution, and a step of washing with water after treating with the aqueous boric acid solution.

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

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

From the viewpoint of thinning, the thickness of the thermoplastic resin film is usually 300 μm or less, preferably 200 μm or less, more preferably 100 μm or less, further preferably 80 μm or less, further preferably 60 μm or less, and usually 5 μm or more, preferably 20 μm or more. The thermoplastic resin film may or may not have a phase difference. The thermoplastic resin film may be bonded to the polarizer using an adhesive layer, for example.

(2) Linear polarizer having polarizer made of film obtained by coating and curing composition containing dichroic dye and polymerizable compound

A linearly polarizing plate having a film obtained by coating and curing a composition containing a dichroic dye and a polymerizable compound as a polarizer will be described. Examples of the film used as a polarizer and obtained by coating and curing a composition containing a dichroic dye and a polymerizable compound include a film obtained by coating a composition containing a dichroic dye having liquid crystallinity or a composition containing a dichroic dye and a liquid crystal compound on a substrate and curing the composition. The film may be used as a linear polarizing plate in which a substrate is peeled off or used together with the substrate, or may be used as a linear polarizing plate having a thermoplastic resin film on one surface or both surfaces thereof.

The substrate may be a thermoplastic resin film. Examples and thicknesses of the base material may be the same as those exemplified in the description of the thermoplastic resin film described above. The substrate may also be a thermoplastic resin film having a hard coat layer, an antireflection layer, or an antistatic layer on at least one surface. The substrate may have a hard coat layer, an antireflection layer, an antistatic layer, or the like formed only on the surface of the side where the polarizer is not formed. The substrate may have a hard coat layer, an antireflection layer, an antistatic layer, and the like formed only on the surface on the side where the polarizer is formed. Examples of the hard coat layer are the same as those of the HC layer forming composition described above in the description of the front panel.

The thermoplastic resin film may be the same as the above-mentioned linearly polarizing plate provided with a stretched film or a stretched layer as a polarizer. The thermoplastic resin film may be bonded to the polarizer using an adhesive layer, for example.

A film obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound is preferably thin, but if it is too thin, the strength tends to decrease and the processability tends to be poor. The thickness of the film is usually 20 μm or less, preferably 5 μm or less, and more preferably 0.5 to 3 μm.

Specific examples of the film obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound include films described in japanese patent application laid-open nos. 2013-37353 and 2013-33249.

(alignment film)

The alignment film may be disposed between the substrate and a layer of a cured product of a composition containing a dichroic dye having liquid crystallinity or a composition containing a dichroic dye and a liquid crystal compound. The alignment film has an alignment regulating force that liquid crystal aligns the liquid crystal layer formed thereon in a desired direction. Examples of the alignment film include an alignment polymer layer formed of an alignment polymer, a photo-alignment polymer layer formed of a photo-alignment polymer, and a groove alignment film having a concave-convex pattern and a plurality of grooves (grooves) on the surface of the layer. The thickness of the alignment film is, for example, 10nm to 500nm, preferably 10nm to 200 nm.

The alignment polymer layer may be formed as follows: the composition is obtained by dissolving an oriented polymer in a solvent, applying the composition to a base material, removing the solvent, and if necessary, subjecting the composition to a rubbing treatment. In this case, in the alignment polymer layer formed of the alignment polymer, the alignment regulating force can be arbitrarily adjusted according to the surface state of the alignment polymer and the rubbing condition.

The photo-alignment polymer layer may be formed by applying a composition including a polymer or monomer having a photoreactive group and a solvent to a substrate layer and irradiating polarized light. In this case, the orientation regulating force in the photo-alignment polymer layer can be arbitrarily adjusted depending on the polarized light irradiation condition of the photo-alignment polymer, and the like.

The groove alignment film may be formed by the following method: for example, a method of forming a concave-convex pattern by exposing and developing the surface of a photosensitive polyimide film through an exposure mask having a slit with a pattern shape; a method in which an uncured layer of an active energy ray-curable resin is formed on a plate-like master having grooves on the surface thereof, and the layer is transferred to a substrate and cured; a method of forming an uncured layer of an active energy ray-curable resin on a substrate, pressing a roll-shaped master having irregularities on the layer to form irregularities, and curing the irregularities.

(protective layer)

The protective layer may be used to protect the surface of the polarizer. In the case where the linearly polarizing plate includes a thermoplastic resin film, the protective layer may be disposed on the opposite side of the polarizer from the thermoplastic resin film. The protective layer may be formed of a resin film exemplified as a material of the thermoplastic resin film, or may be a coating type protective layer. The coating-type protective layer may be obtained by coating and curing a cationically curable composition such as an epoxy resin, or a radically curable composition such as a (meth) acrylate, or may be obtained by coating and drying an aqueous solution of a polyvinyl alcohol resin, and may contain, if necessary, a plasticizer, an ultraviolet absorber, an infrared absorber, a colorant such as a pigment or a dye, a fluorescent whitening agent, a dispersant, a heat stabilizer, a light stabilizer, an antistatic agent, an antioxidant, a lubricant, and the like.

The thickness of the protective layer may be, for example, 200 μm or less, and preferably 0.1 to 100 μm.

(retardation layer)

The retardation layer may include 1 or 2 or more retardation layers. The retardation layer may be a positive A layer and a positive C layer such as a lambda/4 layer and a lambda/2 layer. The retardation layer may be formed of a resin film exemplified as a material of the thermoplastic resin film described above, or may be formed of a layer obtained by curing a polymerizable liquid crystal compound. The retardation layer may further include an alignment film or a substrate. The thickness of the retardation layer may be, for example, 1 μm to 50 μm.

(adhesive layer)

The 1 st adhesive layer is an adhesive layer of the circularly polarizing plate 20 with a double-sided adhesive layer. The 1 st adhesive layer is disposed to bond the circularly polarizing plate 20 with the double-sided adhesive layer and the front panel 10. The 2 nd adhesive layer is an adhesive layer included in the circularly polarizing plate 20 with a double-sided adhesive layer. The 2 nd adhesive layer is disposed to bond the circularly polarizing plate 20 with the double-sided adhesive layer and a rear plate described later. The adhesive layer may be formed using an adhesive composition. The adhesive layer may have a single-layer structure or a multi-layer structure, and preferably has a single-layer structure. The 1 st adhesive layer and the 2 nd adhesive layer may be formed of the same kind of adhesive layer or may be formed of different kinds of adhesive layers.

The adhesive composition may be an adhesive composition containing a resin as a main component, such as a (meth) acrylic resin, a rubber resin, a polyurethane resin, an ester resin, a silicone resin, or a polyvinyl ether resin. Among them, preferred is an adhesive composition containing a (meth) acrylic resin as a base polymer, which is excellent in transparency, weather resistance, heat resistance and the like. The adhesive composition may be an active energy ray-curable type or a heat-curable 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 kinds of (meth) acrylic esters such as butyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, isooctyl (meth) acrylate, isodecyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isobornyl (meth) acrylate as monomers can be preferably used.

The polar monomer is preferably copolymerized in 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-mentioned base polymer, but usually also contains a crosslinking agent. Examples of the crosslinking agent include metal ions having a valence of 2 or more, which form a metal carboxylate with a carboxyl group; polyamine compounds forming amide bonds with carboxyl groups; polyepoxy compounds and polyhydric alcohols forming ester bonds with carboxyl groups; a polyisocyanate compound forming an amide bond with a carboxyl group. Among them, polyisocyanate compounds are preferable.

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

The active energy ray-curable adhesive composition is preferably an ultraviolet-curable adhesive composition. The active energy ray-curable adhesive composition contains an active energy ray-polymerizable compound in addition to a base polymer and a crosslinking agent. Further, a photopolymerization initiator, a photosensitizer, and the like may be contained as necessary.

Examples of the active energy ray-polymerizable compound include (meth) acrylate monomers having at least one (meth) acryloyloxy group in the molecule; a (meth) acrylic compound such as a (meth) acryloyloxy group-containing compound obtained by reacting 2 or more kinds of functional group-containing compounds and having at least 2 (meth) acryloyloxy groups in the molecule, such as a (meth) acrylate oligomer.

The adhesive composition may contain additives such as fine particles, beads (resin beads, glass beads, and the like), glass fibers, resins other than the base polymer, adhesion-imparting agents, fillers (metal powders, other inorganic powders, and the like), antioxidants, ultraviolet absorbers, antistatic agents, dyes, pigments, colorants, antifoaming agents, anticorrosive agents, and photopolymerization initiators for imparting light scattering properties.

The adhesive layer can be formed by coating, for example, an organic solvent dilution of the above adhesive composition on a substrate and drying. When an active energy ray-curable pressure-sensitive adhesive composition is used, a cured product having a desired degree of curing can be obtained by irradiating the pressure-sensitive adhesive layer formed with an active energy ray.

The thickness of the 1 st adhesive layer and the 2 nd adhesive layer is, for example, 0.5 to 100. mu.m, preferably 0.7 to 50 μm, and more preferably 1 to 30 μm, respectively.

The storage elastic modulus at 25 ℃ of the pressure-sensitive adhesive layer is preferably 0.01 to 1.0MPa, more preferably 0.02 to 0.1 MPa. The storage elastic modulus is measured under the following conditions, for example. A plurality of adhesive layers were laminated so as to have a thickness of 0.6 mm. A cylindrical body (height: 0.6mm) having a diameter of 8mm was punched out of the obtained adhesive layer, and this was used as a sample for measurement of storage elastic modulus. The measurement can be carried out by a torsional shear method using a viscoelasticity measuring apparatus in accordance with JIS K7244-6. The frequency may be set to 1 Hz.

[ other constituent elements ]

The laminate 100 may be attached to the back panel by the 2 nd adhesive layer. Examples of the back panel include a touch sensor panel, a display element such as an organic EL display element, and a combination thereof.

Fig. 2 shows a schematic cross-sectional view of another embodiment of a laminate 200. The laminate 200 includes a front panel 10 and a circularly polarizing plate 20 with a double-sided adhesive layer. The circularly polarizing plate 20 with a double-sided adhesive layer comprises a 1 st adhesive layer 30, a linearly polarizing plate 40, a pressure-sensitive adhesive layer 50, a retardation layer 60 and a 2 nd adhesive layer 70 in this order, the linearly polarizing plate 40 comprises a substrate 41, an alignment film 42, a polarizer 43 and a protective layer 44 in this order, and the retardation layer 60 comprises a lambda/4 layer 61, a pressure-sensitive adhesive layer 62 and a positive C layer 63 in this order.

(adhesive layer)

The adhesive layers 50 and 62 are adhesive layers or adhesive layers, and can be formed using an adhesive composition or an adhesive composition. The adhesive layer may have a single-layer structure or a multi-layer structure, but is preferably a single-layer structure. The adhesive composition may be the same as the adhesive composition exemplified in the description of the adhesive layer.

The adhesive composition may be a known adhesive composition, and examples thereof include aqueous adhesive compositions such as a polyvinyl alcohol resin aqueous solution and an aqueous two-pack polyurethane emulsion adhesive; an active energy ray-curable adhesive composition which is cured by irradiation with an active energy ray such as ultraviolet ray.

The adhesive layers 50 and 62 have a thickness of, for example, 0.5 to 100. mu.m, preferably 0.7 to 50 μm, and more preferably 1 to 30 μm.

The laminate 200 may be manufactured by a method including the following steps: and a step of bonding the layers constituting the laminate to each other via the pressure-sensitive adhesive layer and the adhesive layer. When the layers are bonded to each other via the pressure-sensitive adhesive layer or the adhesive layer, it is preferable to subject one or both surfaces of the bonding surface to a surface activation treatment such as corona treatment in order to improve the adhesion.

The polarizer 43 may be formed on the substrate 41 through the alignment film 42. The polarizer 43 can be formed by coating a composition for polarizer formation containing a dichroic dye and a polymerizable liquid crystal compound and curing the composition. The composition for forming a polarizer preferably contains a polymerization initiator, a leveling agent, a solvent, a photosensitizer, a polymerization inhibitor, and the like in addition to the above-mentioned dichroic dye and polymerizable liquid crystal compound.

The retardation layer 60 can be produced by coating a composition for forming a retardation layer containing a polymerizable liquid crystal compound on an alignment film in the presence of a substrate and polymerizing the polymerizable liquid crystal compound.

The composition for forming a retardation layer may further contain a solvent, a polymerization initiator, a photosensitizer, a polymerization inhibitor, a leveling agent, and the like. The substrate and the alignment film may be incorporated into the retardation layer, or may be separated from the retardation layer without becoming a constituent of the laminate.

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

The adhesive layers 30 and 70 may be prepared as adhesive sheets. The adhesive sheet can be produced by the following method or the like: for example, a method in which a pressure-sensitive adhesive liquid is prepared by dissolving or dispersing a pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate, a layer made of a pressure-sensitive adhesive is formed in a sheet form on a release film obtained by subjecting the release film to a mold release treatment, and another release film is further bonded to the pressure-sensitive adhesive layer. Each layer can be attached by attaching the adhesive sheet from which one release film is peeled to one layer, and then peeling the other release film and attaching the other layer. The laminate 200 may be manufactured by attaching the circularly polarizing plate on which the adhesive layer 30 and the adhesive layer 70 are formed to the front panel 10, by attaching the front panel 10 on which the adhesive layer 30 is formed to the circularly polarizing plate on which the adhesive layer 70 is formed, or by attaching the front panel 10 on which the adhesive layer 30 is formed to the circularly polarizing plate and then forming the adhesive layer 70.

< image display device >

The image display device is not particularly limited, and examples thereof include an organic electroluminescence (organic EL) display device, an inorganic electroluminescence (inorganic EL) display device, a liquid crystal display device, a touch panel display device, and an electroluminescence display device. The image display device of the present embodiment has a bendable laminate, and thus can be applied to a flexible display, particularly an organic EL display device.

Examples

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

[ thickness of layer ]

The film thickness was measured using a contact type film thickness measuring apparatus ("MS-5C" manufactured by Nikon K.K.). However, the polarizer, the retardation layer and the alignment film were measured using a laser microscope (LEXT, manufactured by olympus corporation).

[ method for measuring tensile elastic modulus ]

The tensile modulus was measured according to JIS K7161 using UTM (Universal Testing Machine), Autograph AG-X, Shimadzu corporation). The stretching conditions were a speed of 4 mm/min, a width of 10mm and a punctuation distance of 50mm under a moist heat-resistant environment (temperature 60 ℃ C., humidity 90% RH).

[ evaluation of waviness ]

A polyethylene terephthalate (PET) film was attached to the laminates obtained in the examples and comparative examples via the pressure-sensitive adhesive layer included in the laminate, to obtain test pieces. The PET film simulates an image display element and has a thickness of 100 μm. The test piece was cut with a laser beam, subjected to a wet heat bending test under the following conditions, and then the waviness of the bent portion was measured using an interference microscope. The waviness was found as the following: the laminate was placed on an interference microscope with the front panel of the laminate facing upward, and irregularities were observed on the front panel-side surface of the bent portion of the laminate using the interference microscope, and the average value of the height differences between the highest and lowest of the observed irregularities was found (n was 6).

(Wet Heat bending resistance test)

The laminate was placed in an atmosphere at a temperature of 60 ℃ and a relative humidity of 90% RH for 10 days in a state where the front plate side was the inside and the laminate was bent with a curvature radius of 1mm (1R).

[ visibility ]

The laminate after the waviness evaluation was released from the bent state and became a flat state. The laminate was placed under a fluorescent lamp so that the front panel side was upward, and an image of the fluorescent lamp reflected on the laminate surface was observed. In the bent portion, the case where no deformation was observed in the fluorescent lamp image was marked as o, and the case where deformation was observed in the fluorescent lamp image was marked as x.

[ front Panel 1]

(Polyamide-imide film)

14.67g (45.8mmol) of 2, 2' -bis (trifluoromethyl) benzidine (TFMB) and 233.3g of N, N-dimethylacetamide (DMAc) having a water content of 200ppm were put into a 1L separable flask equipped with a stirring blade under a nitrogen atmosphere, and TFMB was dissolved in DMAc while stirring at room temperature. Next, 4.283g (13.8mmol) of 4, 4' -oxydiphthalic dianhydride (OPDA) was added to the flask, and the mixture was stirred at room temperature for 16.5 hours. Then, 1.359g (4.61mmol) of 4, 4' -oxybis (benzoyl chloride) (OBBC) and 5.609g (27.6mmol) of terephthaloyl chloride (TPC) were added to the flask, and stirred at room temperature for 1 hour. Then, 4.937g (48.35mmol) of acetic anhydride and 1.501g (16.12mmol) of 4-methylpyridine were added to the flask, and the mixture was stirred at room temperature for 30 minutes, then heated to 70 ℃ using an oil bath, and further stirred for 3 hours to obtain a reaction solution.

After the obtained reaction solution was cooled to room temperature, 360g of methanol and 170g of ion-exchanged water were added to the reaction solution to obtain a precipitate of polyamideimide. It was immersed in methanol for 12 hours, recovered by filtration and washed with methanol. Next, the precipitate was dried under reduced pressure at 100 ℃ to obtain a polyamide imide (PAI) resin having a thickness of 50 μm.

(HC layer-Forming composition 1)

The composition 1 for forming an HC layer contained 30 parts by mass of a polyfunctional acrylate (Miramer M340, manufactured by mwon Specialty Chemical), 50 parts by mass of a propylene glycol monomethyl ether dispersion of nano silica gel (12nm, solid content 40%), 17 parts by mass of ethyl acetate, 2.7 parts by mass of a photopolymerization initiator (Irgacure-184, manufactured by Ciba Corporation), and 0.3 part by mass of a fluorine-based additive (KY1203, manufactured by shin-Etsu Chemical Co., Ltd.).

(preparation of front Panel 1)

The HC layer-forming composition was applied to one surface of a polyamideimide film, and the obtained coating film was dried at 80 ℃ for 5 minutes, and irradiated with an exposure of 500mJ/cm using a UV irradiation apparatus (SPOT CURE SP-7, manufactured by Ushio Inc.)²UV light (365nm basis) to form the HC layer 1. The coating was performed so that the thickness after curing became 10.0 μm. The front panel 1 having a polyamideimide film with an HC layer of 1/50 μm was obtained as described above.

[ front Panel 2]

A polyamideimide resin having a thickness of 40 μm was obtained in the same manner as in the preparation of the polyamideimide film of the front panel 1 except that 6.140g of 4, 4 '- (hexafluoroisopropylidene) diphthalic dianhydride (6FDA) was used in place of OPDA4.283g, and TFMB8.809g (27.5mmol) and 3.889g (18.3mmol) of 2, 2' -dimethylbenzidine (MB) were used in place of TFMB14.67g (45.8mmol) in the preparation of the polyamideimide film of the front panel 1.

[ front panel 3]

A Cycloolefin (COP) film (40 μm thick, manufactured by Nippon Ralskibushiki Co., Ltd.) was prepared.

[ front panel 4]

A cellulose Triacetate (TAC) film (thickness 40 μm) was prepared.

[ preparation of composition for Forming polarizer ]

(polymerizable liquid Crystal Compound)

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

The 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).

(dichroic dye)

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

(preparation of composition for Forming polarizer)

The composition for forming a polarizer is prepared by the following method: 75 parts by mass of the compound (1-6), 25 parts by mass of the compound (1-7), 2.5 parts by mass of each of the azo dyes represented by the above formulae (2-1 a), (2-1 b) and (2-3 a) as dichroic dyes, 6 parts by mass of 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one (Irgacure369, manufactured by BASF JAPAN) as a polymerization initiator, and 1.2 parts by mass of a polyacrylate compound (manufactured by BYK-361N, BYK-Chemie) as a leveling agent were mixed with 400 parts by mass of toluene as a solvent, and the resulting mixture was stirred at 80 ℃ for 1 hour.

[ adhesive layer 1]

Adhesive compositions for forming the adhesive layer 1 were prepared at the ratios of the respective components shown in table 1 below. The adhesive composition was applied to a release-treated surface of a polyethylene terephthalate film (thickness: 38 μm) subjected to release treatment by an applicator so that the dried thickness became 25 μm. The coating layer was dried at 100 ℃ for 1 minute to obtain a film having the adhesive layer 1. Then, another polyethylene terephthalate film (thickness 38 μm) subjected to a mold release treatment was attached to the pressure-sensitive adhesive layer 1. Then, the mixture was aged at 23 ℃ and 50% RH relative humidity for 7 days.

The symbols in the monomer column in table 1 represent the following meanings.

BA: acrylic acid butyl ester

MMA: acrylic acid methyl ester

EHA: 2-ethylhexyl acrylate

AA: acrylic acid

The following were used as the crosslinking agent and the silane coupling agent in table 1.

A crosslinking agent: CORONATE L (manufactured by Tosoh corporation)

Silane coupling agent: KBM-403 (manufactured by shin-Yue chemical Co., Ltd.)

[ adhesive layer 2]

A film having the pressure-sensitive adhesive layer 2 was obtained in the same manner as the pressure-sensitive adhesive layer 1 except that the thickness after drying was 5 μm.

[ adhesive layer 3]

Adhesive compositions for forming the adhesive layer 3 were prepared at the ratios of the respective components shown in table 1 below. The adhesive composition was applied to a release-treated surface of a polyethylene terephthalate film (thickness: 38 μm) subjected to release treatment by an applicator so that the dried thickness became 5 μm.

The coating layer was dried at 100 ℃ for 1 minute to obtain a film having the adhesive layer 3. Then, another polyethylene terephthalate film (thickness 38 μm) subjected to a mold release treatment was attached to the pressure-sensitive adhesive layer. Then, the mixture was aged at 23 ℃ and 50% RH relative humidity for 7 days.

[ Table 1]

TABLE 1

[ base Material 1]

A cellulose Triacetate (TAC) film (thickness 25 μm) was prepared.

[ base Material 2]

(HC layer-Forming composition 2)

A hard coat layer forming composition 2 was obtained by dissolving 2.0 parts by mass of a dendritic macroacrylate (Miramer SP1106, Miwon Speciality Chemical) having an 18-functional acryloyloxy group (sometimes referred to as an acrylic group), 10.0 parts by mass of a urethane acrylate (Miramer PU-620D, Miwon Speciality Chemical) having a 6-functional acrylic group, 8 parts by mass of an acrylate monomer (M340, Miwon Speciality Chemical), having a 3-functional acrylic group, 2 parts by mass of a photopolymerization initiator (Irgacure (registered trademark) 184, manufactured by BASF corporation) and 0.1 part by mass of a leveling agent (BYK-UV3530, BYK. pan corporation) in 70 parts by mass of Methyl Ethyl Ketone (MEK) and mixing them with stirring.

(production of base Material 2)

The HC layer-forming composition 2 was applied to one surface of a Cycloolefin (COP) film (thickness: 13 μm), and the obtained coating film was dried at a temperature of 80 ℃ for 5 minutes, and then irradiated with an exposure of 500mJ/cm using a UV irradiation apparatus (SPOT CURE SP-7, manufactured by Ushio Inc.)²UV light (365nm basis) to form the HC layer 2. The coating was performed so that the thickness after curing became 2 μm. The substrate 2 was obtained as described above.

[ lambda/4 layer ]

5 parts of a photo-alignment material (weight average molecular weight: 30000) having the following structure and 95 parts of cyclopentanone were mixed, and the resulting mixture was stirred at 80 ℃ for 1 hour to obtain a composition for forming a horizontally aligned film.

And (3) mixing the raw materials in a ratio of 90: a polymerizable liquid crystal compound A and a polymerizable liquid crystal compound B shown below were mixed at a mass ratio of 10 to obtain a mixture, and 100 parts of the mixture was added with 1.0 part of a leveling agent (F-556; manufactured by DIC Co., Ltd.) and 6 parts of 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one ("Irgacure 369(Irg 369)", manufactured by BASF JAPAN Co., Ltd.) as a polymerization initiator.

Further, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration became 13%, and the mixture was stirred at 80 ℃ for 1 hour to obtain a composition (1) for forming a retardation layer.

The polymerizable liquid crystal compound a is produced by the method described in japanese patent application laid-open No. 2010-31223. The polymerizable liquid crystal compound B is produced by the method described in Japanese patent laid-open No. 2009-173893. The respective molecular structures are shown below.

(polymerizable liquid Crystal Compound A)

(polymerizable liquid Crystal Compound B)

A substrate film composed of a cycloolefin polymer (COP) film (ZF-14, manufactured by Nippon Rayle Co., Ltd., thickness: 23 μm) was subjected to corona treatment 1 time using a corona treatment apparatus (AGF-B10, manufactured by Chunshi electric Co., Ltd.) under conditions of an output of 0.3kW and a treatment speed of 3 m/min. The surface of the base material subjected to corona treatment was coated with the composition for forming a horizontally oriented film by a bar coater. The coating film was dried at 80 ℃ for 1 minute using a polarized light UV irradiation apparatus (SPOT CURE SP-7; manufactured by Ushio Inc.) at 100mJ/cm²The cumulative amount of light of (a) is subjected to polarized light UV exposure. The thickness of the obtained horizontally oriented film was measured by a laser microscope (LEXT, manufactured by Olympus corporation), and it was 100 nm.

Then, the composition (1) for forming a phase difference layer was applied to a base film with an alignment film kept at 25 ℃ by a bar coater through a PTFE film filter (ADVANTEC TOYO CO., manufactured by LTD., product No. T300A025A) having a pore diameter of 0.2 μm under an atmosphere of room temperature of 25 ℃ and humidity of 30% RH. The coating film was dried at 120 ℃ for 1 minute, and then irradiated with ultraviolet light (cumulative amount of light at 365nm wavelength under nitrogen atmosphere: 1000 mJ/cm) using a high-pressure mercury lamp (manufactured BY Unicure VB-15201 BY-A, Ushio Inc.)²) Thereby forming an optical film. Using a laser microscope (LEXT,Olympus corporation) was measured, and the thickness of the obtained coating film was 2 μm.

In this way, a laminate (retardation layer 1) in which a layer obtained by curing a polymerizable liquid crystal compound (λ/4 layer), a horizontal alignment film, and a base film were sequentially laminated was obtained. The retardation layer 1 showed reverse wavelength dispersion.

[ Positive C layer ]

As the composition for forming a vertically aligned film, the following mixture was used: mixing the raw materials in a ratio of 1: 1: 4: 5 of 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, dipentaerythritol triacrylate and bis (2-vinyloxyethyl) ether, and 4% of LUCIRIN TPO as a polymerization initiator.

The composition (2) for forming a retardation layer is prepared by adjusting a photopolymerizable nematic liquid crystal compound (RMM 28B, Merck) and a solvent to a solid content of 1 to 1.5 g. The solvent used was 35: 30: 35 Methyl Ethyl Ketone (MEK), methyl isobutyl ketone (MIBK) and Cyclohexanone (CHN).

A polyethylene terephthalate (PET) film having a thickness of 38 μm was prepared as a base film. A composition for forming a vertically aligned film was applied to one surface of a substrate film so as to have a film thickness of 3 μm, and the substrate film was irradiated with 200mJ/cm²The above ultraviolet ray was used to prepare a vertically aligned film.

The composition (2) for forming a retardation layer is coated on the homeotropic alignment layer by die coating. The coating amount is 4-5 g (wet). The coating film was dried at 75 ℃ for 120 seconds. Then, Ultraviolet (UV) light is irradiated to the coating film to polymerize the polymerizable liquid crystal compound. The thickness of the obtained coating film was measured by a laser microscope (LEXT, manufactured by Olympus corporation), and found to be 1 μm.

In this way, a laminate (retardation layer 2) in which a layer (positive C layer) obtained by curing a polymerizable liquid crystal compound, a vertical alignment film, and a base film were sequentially laminated was obtained. The total thickness of the layer of the retardation layer 2 obtained by curing the polymerizable liquid crystal compound and the alignment film was 4 μm.

[ phase difference layer ]

The retardation layer 1 and the retardation layer 2 were bonded together with the pressure-sensitive adhesive layer 3 so that the surface opposite to the surface on the substrate film side was a bonding surface, to obtain a retardation layer having a structure of substrate film/horizontal alignment film/(λ/4 layer)/pressure-sensitive adhesive layer 3/normal C layer/vertical alignment film/substrate film.

< example 1>

First, a substrate 1 is prepared. The composition for forming an alignment film was coated on the substrate 1by a bar coating method. The film was dried at 80 ℃ for 1 minute. Then, the coating film was irradiated with polarized UV light using the UV irradiation apparatus and the wire grid to impart alignment properties to the coating film. The exposure amount was 100mJ/cm²(365nm reference). UIS-27132 # # (manufactured by Ushio Inc.) was used for the wire grid. Thus, an alignment film was formed. The thickness of the alignment film was 100 nm.

The composition for forming a polarizer was coated on the formed alignment film by a bar coating method. The coating film was dried by heating at 100 ℃ for 2 minutes and then cooled to room temperature. Using the UV irradiation apparatus described above, the cumulative light amount was 1200mJ/cm²(365nm standard) ultraviolet rays were irradiated to the coating film, thereby forming a polarizer. The thickness of the resulting polarizer was 3 μm. A composition comprising polyvinyl alcohol and water was applied to a polarizer so that the thickness after drying became 0.5. mu.m, and dried at a temperature of 80 ℃ for 3 minutes to form a protective layer. In this manner, a linear polarizing plate having a structure of substrate 1/alignment film/polarizer/protective layer was produced.

The surface of the front panel 1 opposite to the HC layer 1 and the surface of the pressure-sensitive adhesive layer 1 exposed by peeling off one of the polyethylene terephthalate films provided with the pressure-sensitive adhesive layer 1 were subjected to corona treatment, and then the two were bonded together.

Next, the surface of the pressure-sensitive adhesive layer 1 exposed by peeling the other polyethylene terephthalate film from the pressure-sensitive adhesive layer 1 and the surface of the linearly polarizing plate on the substrate 1 side were subjected to corona treatment, and then the two were bonded together. Then, the surface of the protective layer side of the linearly polarizing plate and the surface of the pressure-sensitive adhesive layer 3 exposed by peeling off one polyethylene terephthalate film of the film provided with the pressure-sensitive adhesive layer 3 were subjected to corona treatment, and then the both were bonded. Next, another polyethylene terephthalate film was peeled off from the adhesive layer 3 to expose the adhesive layer 3. In this way, a laminate having a structure of front panel 1/adhesive layer 1/substrate 1/alignment film/polarizer/protective layer/adhesive layer 3 was obtained.

The base film for forming the retardation layer 1 was peeled off from the retardation layer. The exposed lambda/4 layer is adhered to the adhesive layer 3. The absorption axis of the polarizer makes an angle of 45 with the slow axis of the lambda/4 layer. Next, the base film for forming the retardation layer 2 was peeled off to expose the positive C layer. Then, another film having the pressure-sensitive adhesive layer 1 was prepared, and one polyethylene terephthalate film was peeled off to expose the surface of the pressure-sensitive adhesive layer 1. The exposed surface of the positive C layer and the surface of the pressure-sensitive adhesive layer 1 were subjected to corona treatment, and then both were bonded together. Next, another polyethylene terephthalate film was peeled from the adhesive layer 1. In this way, a laminate of example 1 having a structure of front panel 1/adhesive layer 1/substrate 1/alignment film/polarizer/protective layer/adhesive layer 3/(λ/4 layer)/adhesive layer 3/positive C layer/adhesive layer 1 was obtained. The results are shown in Table 2. In example 1, the circularly polarizing plate with a double-sided adhesive layer was composed of adhesive layer 1/substrate 1/alignment film/polarizer/protective layer/adhesive layer 3/(λ/4 layer)/adhesive layer 3/positive C layer/adhesive layer 1.

< example 2 >

A laminate of example 2 was obtained in the same manner as in example 1, except that the front panel 2 was used instead of the front panel 1 in example 1. The results are shown in Table 2.

< example 3 >

A laminate of example 3 was obtained in the same manner as in example 1, except that the front panel 3 was used instead of the front panel 1 in example 1. The results are shown in Table 2.

< example 4 >

In example 1, a laminate of example 4 was obtained in the same manner as in example 1, except that the substrate 2 was prepared and the composition for forming an alignment film was applied to the HC layer 2 of the substrate 2 instead of the substrate 1 and the composition for forming an alignment film was applied to the substrate 1, and that the film having the pressure-sensitive adhesive layer 2 was used instead of the film having the pressure-sensitive adhesive layer 1. The results are shown in Table 2.

< comparative example 1>

A laminate of comparative example 1 was produced in the same manner as in example 4, except that the front panel 4 was used instead of the front panel 1 in example 4. The results are shown in Table 2.

[ Table 2]

TABLE 2

Description of the symbols

10 front panel, 20 circular polarizer with double-sided adhesive layer, 30 1 st adhesive layer, 40 linear polarizer, 41 substrate, 42 oriented film, 43 polarizer, 44 protective layer, 50 sticking layer, 60 phase difference layer, 61 lambda/4 layer, 62 sticking layer, 63 positive C layer, 70 2 nd adhesive layer, 100, 200 laminated body.