TW202106839A - Laminate - Google Patents

Abstract

The purpose of the present invention is to provide a laminate having improved bending durability under a moist and hot environment. A laminate according to the present invention includes: a front plate; a circular polarizing plate; and a pressure sensitive adhesive layer interposed between the front plate and the circular polarizing plate, wherein the relationship of 0.6 ≤ B/A ≤ 2 is satisfied, where A ([mu]m) denotes the thickness of the laminate, and B(%) denotes the compression restoration rate of the laminate, and B(%) is the proportion (%), with respect to the largest depth of a recess formed by pressing the spherical indentor having a diameter of 0.4 mm from the surface of the front plate side of the laminate toward the inside of the laminate by a force of 100 mN for 60 seconds, of the depth of the recess to be restored when a spherical indentor is removed from the laminate.

Description

Layered body

The present invention relates to a laminated body.

An adhesive film containing an adhesive composition and a display device including a laminate including an adhesive layer formed using such an adhesive film are known (Patent Document 1 to Patent Document 2). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Korean Patent No. 10-2017-0093610 Specification [Patent Document 2] Korean Patent No. 10-2016-0053788 Specification

[The problem to be solved by the invention] The adhesive layer formed using the adhesive film generally has flexible properties, and thereby has excellent stress relaxation performance for alleviating external stress. On the other hand, when the laminate body to which the adhesive layer is applied is bent in a humid and hot environment, cracks such as cracks and ruptures are generated in the laminate body, or bubbles are generated in the adhesive layer. Therefore, it has been pointed out that Insufficient bending durability. Therefore, there is an urgent need to develop a laminate with improved bending durability in a hot and humid environment.

In view of the above-mentioned actual situation, the object of the present invention is to provide a laminate with improved bending durability in a hot and humid environment. [Means to solve the problem]

The present invention provides the following laminate. [1] A laminated body comprising: a front surface plate; a circular polarizing plate; and an adhesive layer interposed between the front surface plate and the circular polarizing plate, wherein, When the thickness of the laminate is A (μm) and the compression recovery rate of the laminate is B (%), the laminate satisfies the relationship of 0.6≦B/A≦2, and The B (%) is obtained by pressing a spherical indenter with a diameter of 0.4 mm from the surface of the laminate body on the front surface plate side into the interior of the laminate body with a force of 100 mN for 60 seconds. When a depression is formed, the ratio (%) of the depth of the depression recovered when the spherical indenter is removed from the laminate to the maximum depth of the depression formed. [2] The laminate according to [1], wherein the A (μm) of the laminate is 150 μm or less. [3] The laminate according to [1] or [2], wherein the circularly polarizing plate includes either a film formed of a liquid crystal layer or a polyvinyl alcohol-based resin film. [4] The laminate according to any one of [1] to [3], wherein the front surface plate is a resin film or a hard-coated hard-coated plate having a hard-coated layer on at least one surface of the resin film Any of resin films. [5] A display device comprising the laminate according to any one of [1] to [4]. [6] The display device according to [5], wherein the display device further includes a back panel, and The back plate is laminated on the circularly polarizing plate side of the laminated body. [7] The display device according to [6], wherein the back panel is a touch sensor panel. [8] The display device according to any one of [5] to [7], wherein the front surface plate side can be bent inside. [Effects of the invention]

According to the present invention, it is possible to provide a laminate having improved bending durability in a hot and humid environment.

Hereinafter, a laminate according to an embodiment of the present invention (hereinafter also simply referred to as "laminate") will be described with reference to the drawings.

〔Laminated body〕 Fig. 1 shows a schematic cross-sectional view of a laminate according to an embodiment of the present invention. In FIG. 1, the laminated body 100 includes a front surface plate 10, a circular polarizing plate 30, and an adhesive layer 20 interposed between the front surface plate 10 and the circular polarizing plate 30. The front surface plate may be any one of a resin film described later or a hard-coated resin film having a hard-coated layer on one surface of the resin film. In the laminated body 100 of FIG. 1, the resin film 12 with the hard coat layer 11 is used as the front surface plate 10. Furthermore, in the laminate 100, the adhesive layer 20 can be formed using an adhesive composition as described later. The circular polarizing plate 30 may include a linear polarizing plate and a retardation layer as described later. In this specification, the "layered body" will be described assuming that it is applied to a display device described later, as long as there is no special description. In this case, the front surface plate is located on the side (visual recognition side) close to the surface of the laminate used in the display device. The circular polarizing plate is located on the side away from the surface of the laminate used in the display device.

The thickness of the layered body 100 varies depending on the functions required for the layered body, the use of the layered body, and the like, so it is not particularly limited, but is preferably 150 μm or less. That is, it is preferable that the layered body 100 has A (μm) of 150 μm or less. The thickness of the layered body 100 is, for example, 50 μm or more and 200 μm or less, preferably 75 μm or more and 150 μm or less, and more preferably 100 μm or more and 130 μm or less.

The shape of the laminated body 100 in plan view may be, for example, a square shape, preferably a square shape having long sides and short sides, and more preferably a 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 50 mm or more and 600 mm or less. The length of the short side may be, for example, 5 mm or more and 800 mm or less, preferably 30 mm or more and 500 mm or less, and more preferably 50 mm or more and 300 mm or less. Each layer constituting the layered body can be R processed at the corners, cut at the ends, or drilled.

The laminated body 100 can be applied to, for example, a display device or the like. That is, the display device of one embodiment of the present invention preferably includes the laminate 100. The display device is not particularly limited, and examples thereof include organic electroluminescence (organic electroluminescence, organic EL) display devices, inorganic electroluminescence (inorganic EL) display devices, liquid crystal display devices, electroluminescence display devices, and the like. The display device may have a touch panel function. Furthermore, the display device to which the laminate 100 is applied can be used as a flexible display that can be bent, wound, or the like. The display device may be capable of bending the front surface plate 10 side to the outside, but it is preferable to be able to curve the front surface plate 10 side to the inside. Furthermore, it is also preferable for the display device to be able to bend the front panel 10 side on the inner side, and be able to bend the front panel 10 side on the outer side.

[Relationship between thickness of laminate and compression recovery rate] When the thickness of the layered body 100 is A (μm) and the compression recovery rate of the layered body 100 is B (%), the layered body 100 satisfies the relationship of 0.6≦B/A≦2. The B (compression recovery rate of the laminated body 100, in %) is achieved by pushing a spherical indenter with a diameter of 0.4 mm from the surface of the laminated body 100 on the side of the front surface plate 10 of the laminated body 100 to the laminated body 100 with a force of 100 mN The ratio (%) of the depth of the recess recovered when the spherical indenter is removed from the laminate when the recess is formed by pressing the inside for 60 seconds to the maximum depth of the formed recess. Specifically, as understood by referring to FIG. 2, the B (%) is a numerical value obtained based on the calculation described below. That is, as shown in FIG. 2, first, in the laminate, a spherical indenter Z with a diameter of 0.4 mm is pressed into the laminate from the surface of the front plate side of the laminate with a force of 100 mN. A depression (recess) is formed in seconds, and the "maximum depth x" of the depression is obtained. Next, after 60 seconds from the time when the spherical indenter Z was removed from the laminate, the "recovered dent depth y" of the recess was determined. Finally, by calculating "the depth y of the restored depression"/"the maximum depth x"×100, the B (%) can be obtained.

When the layered body 100 satisfies the relationship of 0.6≦B/A≦2, even when the layered body 100 is bent in a humid and hot environment, it is possible to suppress the occurrence of cracks, cracks, etc. in the layered body 100, and also suppress The generation of air bubbles in the adhesive layer 20. Therefore, it is possible to provide a laminate 100 having improved bending durability in a hot and humid environment. Specifically, as shown in the embodiments described later, after the laminate 100 is left in a humid and hot environment of 60°C/90%RH for 24 hours, it is placed on the surface of the front surface plate 10 side as a diameter (ϕ) of 20 mm When the mandrel of the following cylindrical jig is bent along the said mandrel, the laminated body 100 may be at least suppressed in the front surface plate 10 such as cracks, cracks, etc., or the adhesive layer 20 may be suppressed The generation of air bubbles (this performance will also be referred to as "excellent wet heat bending durability" below).

Furthermore, as shown in the following examples, the laminate 100 can be used in less than 90 minutes when a pencil with a core hardness of 6B is used to apply a load of 100 g to the surface of the laminate 100 on the front surface plate 10 side. The traces of the recesses formed on the surface disappear (hereinafter, this performance is also referred to as "excellent surface hardness").

The laminate 100 preferably satisfies the relationship of 0.7≦B/A≦1.5, and more preferably satisfies the relationship of 0.8≦B/A≦1. Furthermore, in the laminate 100, the B content is preferably 95% or more, more preferably 98% or more, and still more preferably 99% or more. The B is preferably 100%, but it may be less than 100%. In these cases, even when the layered body 100 is bent under a humid and hot environment, it is possible to sufficiently suppress the generation of cracks such as cracks and cracks in the layered body 100, or the generation of bubbles in the adhesive layer 20.

On the other hand, when the value of B/A in the laminate 100 is less than 0.6, when it is bent in a hot and humid environment, it may not be possible to sufficiently suppress the generation of cracks or adhesives such as cracks and ruptures in the laminate 100. There is a risk of bubbles in layer 20. When the value of B/A in the layered body 100 exceeds 2, there is a possibility that the strength of the layered body 100 may not be sufficient.

In this specification, "curved" includes a form of bending that forms a curved surface at a curved portion. In the form of bending, the radius of curvature of the inner surface of the bending is not limited unless otherwise specified. In addition, as long as there is no special description, "curve" includes a form of bending where the bending angle of the inner surface is greater than 0 degrees and less than 180 degrees, and the radius of curvature of the inner surface is approximately zero, or the bending angle of the inner surface is 0 degree folded form. Hereinafter, specific embodiments of the laminate will be described in more detail.

[Front Panel] The laminated body 100 includes a front surface plate 10. As described above, in the case of being applied to a display device, the front surface plate 10 is located on the side (visibility side) close to the surface of the laminated body 100. As long as the front surface plate 10 is a plate-shaped body capable of transmitting light, the material and thickness are not limited, and may include only one layer or two or more layers. Examples of the front surface plate 10 include resin-made plate-shaped bodies (for example, resin plates, resin sheets, resin films, etc.), glass-made plate-shaped bodies (for example, glass plates, glass films, etc.), and resin-made plates. A laminate of a body and a plate-shaped body made of glass. The front surface plate 10 may constitute the outermost surface of the display device.

The thickness of the front surface plate 10 may be, for example, 30 μm or more and less than 60 μm, preferably 40 μm or more and 55 μm or less, and more preferably 45 μm or more and 50 μm or less. In the present invention, the thickness of each layer can be measured in accordance with the thickness measurement method described in the following Examples.

In the case where the front surface plate 10 is a plate-shaped body made of resin, the plate-shaped body made of resin is not limited as long as it can transmit light. Examples of the resin constituting the plate-shaped body made of resin such as resin film include triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, acryl-based cellulose, butyl-based cellulose, Acetyl propylene cellulose, polyester, polystyrene, polyamide, polyetherimide, poly(meth)acrylic acid, polyimide, polyether chrysene, poly chrysene, polyethylene, polypropylene , Polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyether ether ketone, polymethyl methacrylate, polyethylene terephthalate , Polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyamide imide and other polymer films. These polymers can be used alone or in combination of two or more. From the viewpoint of improving the strength and transparency, a resin film formed of a polymer such as polyimide, polyimide, and polyimide is preferred.

From the viewpoint of increasing the hardness, the front surface plate 101 is preferably a resin film or a hard coat resin film having a hard coat on at least one surface of the resin film. As the resin film, a film made of the above-mentioned resin can be used. The hard coat layer may be formed on one surface of the resin film, or may be formed on both surfaces. By providing a hard coat layer, a resin film with improved hardness and scratch resistance can be made. The hard coat layer is, for example, a cured layer of ultraviolet curable resin. Examples of ultraviolet curable resins include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. In order to increase the hardness, the hard coat layer may contain additives. The additives are not limited, and examples include inorganic fine particles, organic fine particles, or a mixture of these.

When the laminated body 100 is used in a display device, the front surface plate 10 not only has a function of protecting the front surface (screen) of the display device (function as a window film), but also a function as a touch sensor, blue light Cut-off function, viewing angle adjustment function, etc.

[Adhesive layer] The laminated body 100 includes an adhesive layer 20. The adhesive layer 20 is interposed between the front surface plate 10 and the circular polarizing plate 30 described later. The adhesive layer 20 may be, for example, a layer containing an adhesive or an adhesive, or a layer obtained by subjecting the layer to some kind of treatment. The so-called "adhesive" in this specification is also called a pressure-sensitive adhesive. Examples of adhesives include (meth)acrylic adhesives, styrene-based adhesives, silicone-based adhesives, rubber-based adhesives, urethane-based adhesives, polyester-based adhesives, and epoxy-based adhesives. Copolymer adhesives, etc. The adhesive layer 20 may include one layer, two layers, or three or more layers. When the adhesive layer 20 includes two or more layers, the composition of each layer may be the same or different.

The gel fraction of the adhesive layer 20 is preferably 10% by mass to 98% by mass, more preferably 25% by mass to 98% by mass, and still more preferably 45% by mass to 90% by mass. When the gel fraction is in the above range, durability and adhesiveness can be combined. The gel fraction can be measured by the method described in the below-mentioned Examples.

Here, in the present invention, by applying a predetermined adhesive layer to the laminate, the laminate can satisfy the above-mentioned relationship of 0.6≦B/A≦2. The material of the adhesive layer can be obtained by preparing a predetermined adhesive composition. As a method of preparing a predetermined adhesive composition, for example, the predetermined adhesive composition is composed of the adhesive composition A described later, and the composition of the adhesive composition A is changed to the (meth)acrylic polymer A described later. The type of monomers or the method of adjusting the molecular weight of the (meth)acrylic polymer A. In addition, as a predetermined adhesive composition used as the material of the adhesive layer, as long as the laminate satisfies the relationship of 0.6≦B/A≦2 when it is applied to the laminate, it may also include adhesive Composition of components other than composition A (meth)acrylic adhesives, styrene adhesives, silicone adhesives, rubber adhesives, urethane adhesives, polyester adhesives, Adhesive composition such as epoxy-based copolymer adhesive. Hereinafter, the adhesive composition A will be specifically described.

＜Adhesive composition A＞ The adhesive layer may be formed of an adhesive composition containing a (meth)acrylic polymer (hereinafter also referred to as "adhesive composition A"). The adhesive composition A may be an active energy ray hardening type or a thermal hardening type. The "(meth)acrylic polymer" in this specification means at least one selected from the group consisting of acrylic polymers and methacrylic polymers. The same applies to other terms with "(methyl)". When the adhesive composition A contains a plurality of (meth)acrylic polymers, these (meth)acrylic polymers may be the same or different. Hereinafter, the (meth)acrylic polymer contained in the adhesive composition A is also referred to as "(meth)acrylic polymer A".

(Active energy ray hardening adhesive composition) When the adhesive composition A is an active energy ray curable adhesive composition, the (meth)acrylic polymer A contained in the adhesive composition A is derived from a monomer having a reactive functional group The structural unit of is preferably 1% by mass or less based on the total mass of the polymer. Examples of the reactive functional group include a hydroxyl group, a carboxyl group, an amino group, an amide group, and an epoxy group. As a result, the flexibility of the adhesive layer is improved, and when it is bent in a humid and hot environment, it tends to easily suppress the generation of cracks such as cracks and ruptures in the laminate, or air bubbles in the adhesive layer. From the viewpoint of suppressing cracks during bending or the generation of bubbles in the adhesive layer, in the (meth)acrylic polymer A, a structural unit derived from a monomer having a reactive functional group is more preferably a polymer The total mass of is 0.01% by mass or less based on the total mass, and it is more preferable not to have a structural unit derived from a monomer having a reactive functional group, and still more preferably not to have a hydroxyl group, a carboxyl group, an amino group, an amide group, and an epoxy group .

The (meth)acrylic polymer A may include the following structural unit derived from a (meth)acrylic monomer having a linear or branched alkyl group having 1 to 24 carbon atoms . Examples of the (meth)acrylic monomer having a linear or branched alkyl group having 1 or more and 24 carbon atoms include alkyl (meth)acrylate, etc., and examples thereof include : 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, isobornyl (meth)acrylate, and the like. The (meth)acrylic polymer A may be a polymer or copolymer containing one or two or more of the alkyl (meth)acrylates as monomers. The content of the (meth)acrylic polymer A in the adhesive composition A can be, for example, 50% by mass or more and 100% by mass or less, and preferably 80% by mass relative to 100 parts by mass of the solid content of the adhesive composition A % Or more and 99.5% by mass or less, more preferably 90% by mass or more and 99% by mass or less.

The weight average molecular weight (Mw) of the (meth)acrylic polymer A may be, for example, 100,000 or more and 2 million or less. From the viewpoints of suppressing cracks during bending and suppressing bubbles in the adhesive layer, it is preferably 50 More than 10,000 and less than 1.5 million. The weight average molecular weight in this specification can be calculated|required based on the value of the standard polystyrene conversion measured by the gel permeation chromatography (gel permeation chromatography, GPC) method, as demonstrated in the column of an Example mentioned later.

The adhesive composition A may contain one or two or more (meth)acrylic polymers A. Furthermore, the adhesive composition A may contain only the (meth)acrylic polymer A as its constituent component, or may further contain a crosslinking agent. Examples of the crosslinking agent include: a metal ion having a valence of two or more and forming a metal carboxylic acid salt with a carboxyl group; a polyamine compound forming an amide bond with a carboxyl group; a polyepoxy compound or Polyols and those that form ester bonds with carboxyl groups; those that are polyisocyanate compounds and those that form amide bonds with carboxyl groups. Among them, polyisocyanate compounds are preferred. When the adhesive composition A contains a crosslinking agent, relative to 100 parts by mass of the (meth)acrylic polymer A, the content of the crosslinking agent may be, for example, 5 parts by mass or less, preferably 3 parts by mass or less , More preferably 1 part by mass or less, and still more preferably 0.5 part by mass or less. The adhesive composition A sometimes does not contain a crosslinking agent.

The so-called active energy ray-curable adhesive composition means that it has the property of being irradiated with active energy rays such as ultraviolet rays or electron rays and has the property of being hardened, and has adhesiveness even before the active energy ray is irradiated, so that it can bond with the film, etc. Adhesive composition that is in close contact with the adherend and is cured by the irradiation of active energy rays to adjust the properties such as adhesion. The active energy ray curable adhesive composition is preferably an ultraviolet curable adhesive composition.

When the adhesive composition A is an active energy ray curable adhesive composition, the adhesive composition A may further contain an active energy ray polymerizable compound, a photopolymerization initiator, a photosensitizer, and the like.

As the active energy ray polymerizable compound, for example, a (meth)acrylate monomer having at least one (meth)acryloyloxy group in the molecule; obtained by reacting two or more functional group-containing compounds, and The (meth)acrylate oligomer having at least two (meth)acryloxy groups and the like are (meth)acrylic compounds such as (meth)acryloxy group-containing compounds. With respect to 100 parts by mass of the solid content of the adhesive composition A, the adhesive composition A may contain 0.1 parts by mass or more and 10 parts by mass or less of the active energy ray polymerizable compound.

As a photopolymerization initiator, benzophenone, benzil dimethyl ketal, 1-hydroxycyclohexyl ketone, etc. are mentioned, for example. When the adhesive composition A contains a photopolymerization initiator, it may contain one kind or two or more kinds. When the adhesive composition A contains a photopolymerization initiator, the total content thereof may be 0.01 part by mass or more and 1.0 part by mass or less with respect to 100 parts by mass of the solid content of the adhesive composition A, for example.

The adhesive composition A may contain fine particles, beads (resin beads, glass beads, etc.), glass fibers, resins other than raw polymers, adhesiveness imparting agents, fillers (metal powder or other inorganic powders) for imparting light scattering properties. Etc.), antioxidants, ultraviolet absorbers, dyes, pigments, colorants, defoamers, anti-corrosion agents and other additives. From the viewpoint of preventing the problem of durability reduction caused by the residual solvent, the adhesive composition A preferably does not contain an organic solvent.

In the case where the adhesive layer is formed of the adhesive composition A, the adhesive layer can be formed by coating the adhesive composition A on the substrate. In the case of using an active energy ray-curable adhesive composition, the adhesive layer formed of the adhesive composition A can be irradiated with active energy rays to produce a cured product having a desired degree of curing.

(Thermosetting adhesive composition) When the adhesive composition A is a thermosetting adhesive composition, the (meth)acrylic polymer A is preferably an alkyl (meth)acrylate having 2 to 20 carbon atoms, And a monomer having a reactive functional group in the molecule (a monomer containing a reactive functional group) is used as a monomer unit constituting the polymer. In the case of a thermosetting adhesive composition, the adhesive composition A preferably further contains a thermal crosslinking agent.

The (meth)acrylic polymer A has an alkyl (meth)acrylic acid alkyl ester having 2 to 20 carbon atoms as a monomer unit constituting the polymer, and thus can exhibit better adhesiveness. The alkyl (meth)acrylate having 2 to 20 carbon atoms in the alkyl group preferably contains, for example, a homopolymer having a glass transition temperature (Tg) of -40°C or less (hereinafter sometimes referred to as "low Tg acrylate alkyl ester"). By containing the low Tg alkyl acrylate as a structural monomer unit, the flexibility of the adhesive layer is improved, and therefore, cracks during bending or the generation of bubbles in the adhesive layer can be suppressed more easily. The glass transition temperature (Tg) of the (meth)acrylic polymer A can be obtained by using a conventionally known method such as differential thermal analysis (DTA).

As low Tg alkyl acrylates, for example, n-butyl acrylate (Tg is -54°C), n-octyl acrylate (Tg is -65°C), isooctyl acrylate (Tg is -58°C) , 2-ethylhexyl acrylate (Tg is -70°C), isononyl acrylate (Tg is -58°C), isodecyl acrylate (Tg is -60°C), isodecyl methacrylate (Tg is- 41°C), n-lauryl methacrylate (Tg is -65°C), tridecyl acrylate (Tg is -55°C), tridecyl methacrylate (Tg is -40°C), etc. Among them, as the low-Tg alkyl acrylate, the homopolymer has a Tg of -45°C or lower, and particularly preferably -50°C or lower. Specifically, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferred. These can be used alone or in combination of two or more.

In the (meth)acrylic polymer A, as the monomer unit constituting the polymer, the following limit is preferably 85% by mass or more of the low Tg alkyl acrylate, more preferably 90% by mass or more, and further It is preferable to contain 95% by mass or more.

Furthermore, in the (meth)acrylic polymer A, as the monomer unit constituting the polymer, it is preferable that the above-mentioned limit contains the low Tg alkyl acrylate in an amount of 99.9% by mass or less, and more preferably 99.5 mass%. % Or less, more preferably 99% by mass or less. By containing 99.9% by mass or less of the low Tg alkyl acrylate, an appropriate amount of other monomer components (especially a monomer containing a reactive functional group) can be introduced into the (meth)acrylic polymer A.

From the viewpoint of further exerting the effects of the present invention, the (meth)acrylic polymer A preferably has as little as possible a homopolymer whose glass transition temperature (Tg) exceeds 0°C (hereinafter sometimes referred to as "Hard monomer") content. Specifically, in the (meth)acrylic polymer A, as the monomer unit constituting the polymer, the content of the hard monomer is preferably set to 15% by mass or less, and more preferably set to 10 in terms of the above limit. Mass% or less, more preferably 5 mass% or less. The hard monomer also includes the reactive functional group-containing monomer described later.

As the hard monomer, for example, methyl acrylate (Tg is 10°C), methyl methacrylate (Tg is 105°C), ethyl methacrylate (Tg is 65°C), n-butyl methacrylate Esters (Tg is 20°C), isobutyl methacrylate (Tg is 48°C), tertiary butyl methacrylate (Tg is 107°C), n-stearyl acrylate (Tg is 30°C), methacrylic acid Stearyl ester (Tg is 38°C), cyclohexyl acrylate (Tg is 15°C), cyclohexyl methacrylate (Tg is 66°C), phenoxyethyl acrylate (Tg is 5°C), methyl Phenoxyethyl acrylate (Tg is 54°C), benzyl methacrylate (Tg is 54°C), isobornyl acrylate (Tg is 94°C), isobornyl methacrylate (Tg is 180°C), acrylic Acrylic morpholine (Tg is 145°C), adamantyl acrylate (Tg is 115°C), adamantyl methacrylate (Tg is 141°C), acrylic acid (Tg is 105°C), dimethyl acrylate Acrylic monomers such as amine (Tg: 89°C), acrylamide (Tg: 165°C), vinyl acetate (Tg: 32°C), styrene (Tg: 80°C), etc.

The (meth)acrylic polymer A contains a reactive functional group-containing monomer as a monomer unit constituting the polymer, and passes through the reactive functional group derived from the reactive functional group-containing monomer to be described later. The thermal crosslinking agent reacts. By this, a crosslinked structure (three-dimensional network structure) is formed as a whole, and an adhesive having a desired cohesive force can be obtained.

As the monomer containing a reactive functional group contained in the (meth)acrylic polymer A as a monomer unit constituting the polymer, a monomer having a hydroxyl group in the molecule (a hydroxyl group-containing monomer Monomers), monomers having carboxyl groups in the molecule (carboxyl group-containing monomers), monomers having amine groups in the molecule (amine group-containing monomers), etc. Among these, in many cases where the glass transition temperature (Tg) is 0° C. or less, a hydroxyl group-containing monomer is particularly preferred.

Examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2 (meth)acrylic acid. -Hydroxyalkyl (meth)acrylates such as hydroxybutyl, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. Among them, in terms of the glass transition temperature (Tg), the reactivity of the hydroxyl group in the obtained (meth)acrylic polymer A with the thermal crosslinking agent, and the copolymerizability with other monomers, it is preferably At least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, and 4-hydroxybutyl acrylate. These can be used alone or in combination of two or more.

Examples of carboxyl group-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These can be used alone or in combination of two or more.

Examples of the amine group-containing monomer include aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, and the like. These can be used alone or in combination of two or more.

In the (meth)acrylic polymer A, as the monomer unit constituting the polymer, the following limit is preferably 0.1% by mass or more of the reactive functional group-containing monomer, particularly preferably 0.5% by mass or more It is more preferable to contain 1% by mass or more. In the (meth)acrylic polymer A, the above limit is preferably 10% by mass or less of the reactive functional group-containing monomer, particularly preferably 8% by mass or less, and more preferably 5% by mass. the following. This tends to more easily suppress the generation of cracks or bubbles in the adhesive layer during bending.

In the (meth)acrylic polymer A, as a monomer unit constituting the polymer, a carboxyl group-containing monomer, particularly acrylic acid, which is also a hard monomer, may not be contained. The carboxyl group is an acid component. Therefore, by not containing a carboxyl group-containing monomer, even if there is a problem caused by acid in the sticking object of the adhesive, such as tin-doped indium oxide (indium tin oxide, ITO) )) In the case of transparent conductive films, metal films, metal meshes, etc., these disadvantages (corrosion, resistance value changes, etc.) due to acid can also be suppressed.

The (meth)acrylic polymer A may also contain other monomers as monomer units constituting the polymer as necessary. As other monomers, in order not to hinder the function of the reactive functional group-containing monomer, it is also preferable that the monomer does not contain a reactive functional group. As the other monomers, for example, in addition to alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, etc., as homopolymers, A monomer whose glass transition temperature (Tg) exceeds -40°C and is below 0°C (hereinafter sometimes referred to as "medium Tg alkyl acrylate"), etc. Examples of medium Tg alkyl acrylates include ethyl acrylate (Tg is -20°C), isobutyl acrylate (Tg is -26°C), and 2-ethylhexyl methacrylate (Tg is -10°C) , Lauryl acrylate (Tg is -23°C), Isostearyl acrylate (Tg is -18°C), etc. These can be used alone or in combination of two or more.

The polymerization state of the (meth)acrylic polymer A may be a random copolymer or a block copolymer.

The lower limit of the weight average molecular weight of the (meth)acrylic polymer A is preferably 200,000 or more, particularly preferably 300,000 or more, and still more preferably 400,000 or more. If the lower limit of the weight average molecular weight of the (meth)acrylic polymer A is more than the above, it is possible to suppress defects such as leaching of the adhesive.

The upper limit of the weight average molecular weight of the (meth)acrylic polymer A is preferably 2 million or less, particularly preferably 1.5 million or less, and more preferably 1.3 million or less. If the upper limit value of the weight average molecular weight of the (meth)acrylic polymer A is the above-mentioned or less, the flexibility of the adhesive layer can be ensured, and the effect of the present invention can be easily exhibited.

In the adhesive composition A, the (meth)acrylic polymer A may be used alone or in combination of two or more.

When the adhesive composition A containing the thermal crosslinking agent is heated, the thermal crosslinking agent crosslinks the (meth)acrylic polymer A to form a three-dimensional network structure. Thereby, the cohesive force can be improved while ensuring the flexibility of the adhesive, and when applied to a laminate, the hardness that can increase the surface hardness of the laminate can be obtained.

The thermal crosslinking agent may be one that reacts with the reactive group possessed by the (meth)acrylic polymer A, and examples thereof include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, and amine-based crosslinking agents. Linking agent, melamine-based cross-linking agent, aziridine-based cross-linking agent, hydrazine-based cross-linking agent, aldehyde-based cross-linking agent, oxazoline-based cross-linking agent, metal alkoxide-based cross-linking agent, metal chelate Series cross-linking agent, metal salt-based cross-linking agent, ammonium salt-based cross-linking agent, etc. Among the above, when the reactive group possessed by the (meth)acrylic polymer A is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent having excellent reactivity with the hydroxyl group. The thermal crosslinking agent can be used alone or in combination of two or more.

The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; isophorone diisocyanate, Hydrogenated diphenylmethane diisocyanate and other alicyclic polyisocyanates, etc.; and these biuret bodies, isocyanurate bodies, and as a combination with ethylene glycol, propylene glycol, neopentyl glycol, and trimethylolpropane , Castor oil and other low-molecular-weight active hydrogen-containing compounds reaction products adducts, etc. Among them, from the viewpoint of reactivity with hydroxyl groups, aromatic polyisocyanates modified with trimethylolpropane are preferred, and toluene diisocyanate modified with trimethylolpropane and trimethylolpropane modified are particularly preferred. Xylylene diisocyanate.

Examples of epoxy-based crosslinking agents include: 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl- M-xylylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine, etc.

Relative to 100% by mass of the (meth)acrylic polymer A, the content of the thermal crosslinking agent in the adhesive composition A is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.1% by mass %the above. Furthermore, the content is preferably 1% by mass or less, more preferably 0.8% by mass or less, and still more preferably 0.5% by mass or less. When the content of the thermal crosslinking agent is in the above range, it is possible to more easily obtain a moderate hardness by improving the cohesive force.

The adhesive composition A preferably contains the silane coupling agent. Thereby, the adhesive layer becomes a thing which improves the adhesiveness between each member in a laminated body, and is more excellent in durability against bending.

As a silane coupling (SC) agent, it is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule, and has good compatibility with (meth)acrylic polymer A and has light transmittance Sexual silane coupling agent.

Examples of the silane coupling agent include: vinyl trimethoxy silane, vinyl triethoxy silane, methacryloxy propyl trimethoxy silane, and other polymerizable unsaturated group-containing silicon compounds; 3-condensation Silicon compounds with epoxy structure such as glyceroxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc.; 3-mercaptopropyltrimethoxysilane, 3-mercapto Sulfhydryl-containing silicon compounds such as propyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane; 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3 -Aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane and other amino-containing silicon compounds; 3-chloropropyltrimethoxy Silane, 3-isocyanate propyltriethoxysilane, or at least one of these and methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, etc. Condensates of alkyl-containing silicon compounds, etc. These can be used singly or in combination of two or more.

Relative to 100% by mass of the (meth)acrylic polymer A, the content of the silane coupling agent in the adhesive composition A is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.1% by mass the above. Furthermore, the content is preferably 1% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.3% by mass or less. When the content of the silane coupling agent is in the above range, the adhesion between the members in the laminate can be further improved.

In the adhesive composition A, the various additives described above can be added as necessary. In this specification, the polymerization solvent and the dilution solvent are regarded as not included in the additives constituting the adhesive composition A.

The (meth)acrylic polymer A can be produced by polymerizing a mixture of monomers constituting the polymer by a normal radical polymerization method. The polymerization of the (meth)acrylic polymer A is preferably carried out by a solution polymerization method using a polymerization initiator as necessary. As a polymerization solvent, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, etc. are mentioned, for example, You may use 2 or more types together.

Examples of the polymerization initiator include azo compounds, organic peroxides, and the like, and two or more of them may be used in combination. As the azo compound, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane 1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxypentane) Nitrile), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis( 2-hydroxymethylpropionitrile), 2,2'-azobis[2-(2-imidazolin-2-yl)propane] and the like.

Examples of organic peroxides include: benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, peroxy Di(2-ethoxyethyl) oxydicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxypivalate, (3,5,5-trimethylhexyl peroxide) ), dipropylene peroxide, diacetyl peroxide, etc.

In the polymerization step, the weight average molecular weight of the obtained polymer can be adjusted by formulating a chain transfer agent such as 2-mercaptoethanol.

After the (meth)acrylic polymer A is obtained, add a thermal crosslinking agent, a silane coupling agent, and if necessary additives and a diluent solvent to the solution of the (meth)acrylic polymer A, and mix them thoroughly, thereby The adhesive composition A (coating solution) diluted with a solvent can be obtained. The adhesive composition A can be produced by mixing the components together using a known method, for example, a mixer or the like.

In any of the above-mentioned components, when a solid one is used, or when precipitation occurs when mixed with other components in an undiluted state, the component may be separately pre-dissolved or diluted in Dilute the solvent and mix with other ingredients.

As the dilution solvent, for example, aliphatic hydrocarbon solvents such as hexane, heptane, and cyclohexane; aromatic hydrocarbon solvents such as toluene and xylene; halogenated hydrocarbon solvents such as dichloromethane and dichloroethane can be used. ; Alcohol solvents such as methanol, ethanol, propanol, butanol, 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone Solvents; ester-based solvents such as ethyl acetate and butyl acetate; and siloxu-based solvents such as ethyl siloxu.

The concentration and viscosity of the adhesive composition A (coating solution) prepared in this way are not particularly limited as long as they are in a range that can be applied, and can be appropriately selected according to the situation. For example, the concentration of the adhesive composition A can be adjusted to be 10% by mass to 60% by mass in the solution. When obtaining the coating solution, the addition of a dilution solvent and the like is not a necessary condition, and if the adhesive composition A has a viscosity or the like that can be applied, the dilution solvent may not be added. In this case, the adhesive composition A becomes a coating solution in which the polymerization solvent of the (meth)acrylic polymer A is directly used as a diluting solvent.

The adhesive layer can be obtained by crosslinking the adhesive composition A. The crosslinking of the adhesive composition A can be performed by heat treatment. The heat treatment may also be compatible with drying treatment when the coating film of the adhesive composition A obtained by applying a dilution solvent or the like to a desired object is volatilized.

The heating temperature of the heat treatment is preferably 50°C to 150°C, more preferably 70°C to 120°C. The heating time of the heat treatment is preferably 10 seconds to 10 minutes, more preferably 50 seconds to 2 minutes.

After the heat treatment, a curing period of about 1 to 2 weeks can be set at normal temperature (for example, 23° C., 50% RH) as needed. In the case where the curing period is required, the adhesive layer can be formed after the curing period has passed. In the case where the curing period is not required, the adhesive layer can be formed after the above-mentioned heat treatment is completed.

Through the heat treatment (and curing), the (meth)acrylic polymer A is sufficiently cross-linked via the cross-linking agent to form a cross-linked structure, thereby obtaining an adhesive layer.

＜Adhesive sheet＞ The adhesive sheet may include an adhesive layer formed of the adhesive composition A. The adhesive layer can be formed by coating the adhesive composition A on the substrate. In the case of using an active energy ray curable adhesive composition as the adhesive composition A, the formed adhesive layer can be irradiated with active energy rays to produce a cured product having a desired degree of curing. In the case of using a thermosetting adhesive composition as the adhesive composition, the formed adhesive layer can be heated (and cured) to produce a cured product having a desired degree of curing.

The substrate may be a release film that has been subjected to a mold release treatment. The adhesive sheet can be produced by coating the adhesive composition A on a release film to form an adhesive layer in a sheet shape, and then sticking another release film on the adhesive layer.

As a method of applying the coating liquid of the adhesive composition A, for example, a bar coating method, a knife coating method, a roll coating method, a knife coating method, a die coating method, a gravure coating method, etc. can be used.

[Circular Polarizing Plate] The laminated body 100 includes a circular polarizing plate 30. The circular polarizer 30 may include a linear polarizer and a retardation layer, and the linear polarizer may be disposed on the side of the adhesive layer 20. In the case where the laminated body 100 is applied to a display device, the circularly polarizing plate 30 is located on the side away from the surface of the laminated body 100 applied to the display device as described above. When the laminated body 100 is applied to a display device, the circular polarizing plate 30 can convert light (external light) incident through the laminated body 100 from the visible side of the display device into circularly polarized light. Furthermore, since the circularly polarizing plate 30 can absorb external light reflected by the display element in the image display device, the laminated body 100 can be provided with a function as an anti-reflection film. The circular polarizing plate 30 preferably includes any one of a film formed of a liquid crystal layer or a polyvinyl alcohol-based resin film as described below. The circular polarizing plate 30 is particularly preferably a polarizing plate including a film formed of a liquid crystal layer or a polyvinyl alcohol-based resin film as a linear polarizing plate.

＜Linear polarizing plate＞ The linear polarizing plate has a function of selectively transmitting unidirectional linearly polarized light including non-polarized light such as natural light. The linear polarizing plate may include a stretched film to which a dichroic dye is adsorbed, or a film obtained by applying and hardening a dichroic dye as a polarizer. As a film formed by applying a dichroic dye and hardening it, it is possible to use a composition coated with a dichroic dye having liquid crystallinity, or a composition containing a dichroic dye and polymerizable dye. The composition of the liquid crystal compound is hardened to obtain the film, etc. of the layer. As the dichroic dye, specifically, iodine or a dichroic organic dye can be used. The dichroic organic dyes include: C.I. DIRECT RED 39 and other dichroic direct dyes containing bisazo compounds; and dichroic direct dyes containing compounds such as trisazo and tetraazo. Compared with a stretched film in which a dichroic dye is adsorbed, a film formed by applying and hardening a dichroic dye has no limitation in the bending direction, and is therefore preferable.

(The stretched film with the dichroic pigment adsorbed becomes the linear polarizing plate of the polarizer) Hereinafter, the linear polarizing plate in which the stretched film to which the dichroic dye is adsorbed becomes a polarizer will be described. A stretched film adsorbing a dichroic dye is usually manufactured by going through the following steps: a step of uniaxially stretching a polyvinyl alcohol-based resin film, and by dyeing the polyvinyl alcohol-based resin film with a dichroic dye The step of making it adsorb the dichroic pigment, the step of treating the polyvinyl alcohol resin film on which the dichroic pigment has been adsorbed with an aqueous solution of boric acid, and the step of treating the adsorbed dichroic pigment after the treatment with the aqueous solution of boric acid The step of washing the polyvinyl alcohol-based resin film of the sex dye with water. The stretched film to which the dichroic dye is adsorbed produced by the above steps can be used directly as a linear polarizing plate, or it can be used as a linear polarizing plate after laminating a transparent protective film on one or both sides. The thickness of the polarizer (stretched film to which the dichroic dye is adsorbed) thus obtained is preferably 2 μm to 40 μm.

The polyvinyl alcohol-based resin is obtained by saponifying a polyvinyl acetate-based 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 other monomers that can be copolymerized therewith, or the like can also be used. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides having an ammonium group.

The degree of saponification of the polyvinyl alcohol-based resin is generally about 85 mol% to 100 mol%, and preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually about 1,000 to 10,000, and preferably in the range of 1,500 to 5,000.

By forming such a polyvinyl alcohol-based resin into a film, a full-width film (that is, a polyvinyl alcohol-based resin film) that becomes a material of the polarizer can be obtained. The method of forming a polyvinyl alcohol-based resin into a film is not particularly limited, and the film can be formed by a known method. The film thickness of the polyvinyl alcohol-based resin film can be set to, for example, about 1 μm to 100 μm.

The uniaxial stretching of the polyvinyl alcohol-based resin film may be performed before dyeing with a dichroic dye, simultaneously with dyeing, or after dyeing. In the case of performing uniaxial stretching after dyeing, the uniaxial stretching may be performed before the boric acid treatment or may be performed during the boric acid treatment. Furthermore, it is also possible to perform uniaxial stretching in these multiple stages. In the case of uniaxial stretching, it can be stretched uniaxially between rolls with different peripheral speeds, or it can be stretched uniaxially using a heated roll. Uniaxial stretching may be dry stretching in which it is stretched in the air, or wet stretching in which a polyvinyl alcohol-based resin film is stretched while swelling the polyvinyl alcohol-based resin film using a solvent. The stretching ratio is usually about 3 to 8 times.

The thickness of the linear polarizing plate including the stretched film as a polarizer may be, for example, 1 μm or more, 5 μm or more, or 7 μm or more. The thickness of the linear polarizer including the stretched film as a polarizer may be 100 μm or less, 50 μm or less, 20 μm or less, or 10 μm or less.

The material of the transparent protective film attached to one or both sides of the polarizer is not particularly limited, and examples include: cyclic polyolefin resin film; acetic acid containing resins such as triacetyl cellulose and diacetyl cellulose Cellulose resin film; polyester resin film containing resins like polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate resin film; Meth) acrylic resin film; polypropylene resin film is equivalent to a film known in this technical field. From the viewpoint of thinning, the thickness of the transparent protective film is generally 300 μm or less, preferably 200 μm or less, and more preferably 100 μm or less. The thickness of the transparent protective film is usually 5 μm or more, preferably 20 μm or more. The transparent protective film may or may not have a phase difference.

(The film formed by applying dichroic dye and hardening it becomes a linear polarizing plate of the polarizer) Next, the film formed by applying and curing a dichroic dye becomes a linear polarizing plate of a polarizer. As a film formed by applying a dichroic dye and curing it, a composition having a coating composition as described above, that is, a composition containing a dichroic dye having liquid crystallinity, or a composition containing a dichroic dye can be used And a film of a layer obtained by curing a composition of a polymerizable liquid crystal compound (hereinafter, these are collectively referred to as a "film formed of a liquid crystal layer") and the like. The film formed of the liquid crystal layer can be used as a linear polarizing plate by peeling off the base material or together with the base material, or can also be used as a linear polarizing plate after laminating a transparent protective film on one or both sides. As this transparent protective film, the same material as the above-mentioned transparent protective film bonded to the linear polarizing plate which becomes a polarizer of a stretched film can be used.

Specific examples of the film formed of the liquid crystal layer include films described in Japanese Patent Laid-Open No. 2013-37353 or Japanese Patent Laid-Open No. 2013-33249.

The film formed of the liquid crystal layer is preferably thinner, but if it is too thin, the strength decreases and the workability 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 μm or more and 3 μm or less. The thickness of the linear polarizing plate where the film formed of the liquid crystal layer becomes the polarizer can be, for example, 1 μm or more and 50 μm or less.

＜Retardation layer＞ The retardation layer may be one layer, or two or more layers. The retardation layer may have an overcoat layer to protect its surface, a base film that supports the retardation layer, and the like. The retardation layer includes a λ/4 layer, and may further include at least one of a λ/2 layer and a positive C layer. In the case where the retardation layer includes a λ/2 layer, a λ/2 layer and a λ/4 layer are sequentially laminated from the side of the linear polarizer. In the case where the retardation layer includes a positive C layer, a λ/4 layer and a positive C layer may be sequentially laminated from the linear polarizer side, or a positive C layer and a λ/4 layer may be sequentially laminated from the linear polarizer side. The thickness of the retardation layer is, for example, 0.1 μm or more and 10 μm or less, preferably 0.5 μm or more and 8 μm or less, and more preferably 1 μm or more and 6 μm or less.

The retardation layer may be formed of the resin film exemplified as the material of the transparent protective film described above, or may be formed of a layer formed by curing a polymerizable liquid crystal compound. The retardation layer may further include an alignment film and a base film, and may also have a layer including an adhesive or adhesive for bonding the λ/4 layer, the λ/2 layer, and the positive C layer (hereinafter also referred to as "sticker"). "Co-layer").

In the case of forming a layer formed by curing a polymerizable liquid crystal compound, the retardation layer can be formed by applying a composition containing a polymerizable liquid crystal compound to a base film and curing it. An alignment layer may also be formed between the base film and the coating layer. The material and thickness of the base film may be the same as the material and thickness of the resin film (the transparent protective film). In the case of being formed from a layer formed by curing a polymerizable liquid crystal compound, the retardation layer may be assembled in a laminate in the form of an alignment layer and a base film. Furthermore, the retardation layer can be bonded to the linear polarizing plate via the bonding layer mentioned later.

(Laminated layer) The bonding layer is a layer containing an adhesive or adhesive. The adhesive that becomes the material of the bonding layer can use the same adhesive composition as the adhesive composition that becomes the material of the adhesive layer 20. For other adhesives, for example, (methyl) that is different from the material of the adhesive layer 20 can be used. ) Acrylic adhesives, styrene adhesives, silicone adhesives, rubber adhesives, urethane adhesives, polyester adhesives, epoxy copolymer adhesives, etc.

Furthermore, the "adhesive" used as the material of the bonding layer refers to an adhesive other than an adhesive (pressure-sensitive adhesive), and is clearly distinguished from an adhesive. As the adhesive used as the material of the bonding layer, for example, it can be formed by combining one or two or more of water-based adhesives, active energy ray curable adhesives, and the like. Examples of the water-based adhesive include a polyvinyl alcohol-based resin aqueous solution, an aqueous two-component urethane-based emulsion adhesive, and the like. Active energy ray curable adhesives are adhesives that are cured by irradiating active energy rays such as ultraviolet rays. Examples include adhesives containing polymerizable compounds and photopolymerizable initiators, adhesives containing photoreactive resins, and Adhesives for adhesive resins and photoreactive crosslinking agents. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, and monomers derived from these monomers. Oligomers and so on. Examples of the photopolymerization initiator include a compound containing a substance that generates active species such as neutral radicals, anionic radicals, and cationic radicals by irradiating active energy rays such as ultraviolet rays.

The thickness of the bonding layer is not particularly limited. When the adhesive layer is used as the bonding layer, it is preferably 1 μm or more, may be 5 μm or more, may be 10 μm or more, or may be 15 μm or more, And it is usually 50 μm or less, but may also be 25 μm or less. When the adhesive layer is used as the bonding layer, the thickness of the bonding layer is preferably 0.1 μm or more, may be 0.5 μm or more, and is preferably 10 μm or less, or may be 5 μm or less.

[Manufacturing method of laminated body] The laminated body 100 can be manufactured by a method including a step of bonding the front surface plate 10 and the circular polarizing plate 30 through the adhesive layer 20. Furthermore, the layers constituting the layered body 100 may be bonded via the bonding layer described above as necessary. When the layers are bonded to each other via the adhesive layer 20 or the bonding layer, in order to improve adhesion, it is preferable to perform surface activation treatment such as corona treatment on one or both of the bonding surfaces.

The circular polarizing plate 30 can be directly formed on a transparent protective film or a base film as described above, and the transparent protective film or base film may be assembled in the laminate 100, or it may be peeled off from the circular polarizing plate 30 instead of being a laminate. 100 components.

[Display device] A display device according to an embodiment of the present invention includes the laminate 100 described above. 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 electroluminescence display devices. The display device may also have a touch panel function. The laminated body 100 suppresses cracks such as cracks and cracks in the laminated body 100 or the generation of air bubbles in the adhesive layer 20 even when it is bent in a humid and hot environment, and is therefore preferably used for having a bendable or Flexible display device such as bending. As a constituent member used in a display device, for example, in addition to the image display device, a separator may be included.

In the display device, the front surface plate 10 side of the laminated body 100 is arranged on the side opposite to the display element side, that is, the visible side of the display element included in the display device. The display device may be capable of bending the front surface plate 101 side on the inside, or bending the front surface plate 10 side on the outside, but it is preferable that the front surface plate 10 side be bent on the inside. Furthermore, it is also preferable for the display device to be able to bend the front panel 10 side on the inner side, and be able to bend the front panel 10 side on the outer side.

[Back Panel] The display device may further include a back panel. The back plate is preferably laminated on the circularly polarizing plate 30 side of the laminated body 100. Specifically, in addition to the front surface plate 10, the adhesive layer 20, and the circular polarizing plate 30 included in the case where the laminate 100 of FIG. 1 is used for description, this type of display device also includes a back plate adjacent to and laminated on the laminate layer The state of the body 100 on the side of the circular polarizer 30. The back plate may be laminated on the circular polarizing plate 30 via the above-mentioned lamination layer. As the back panel, a touch sensor panel, other plate-shaped bodies that can transmit light, etc. are sometimes used, but the back panel is preferably a touch sensor panel. Hereinafter, these components will be described.

＜Touch sensor panel＞ The present invention can use the touch sensor panel as the back panel. As the touch sensor panel, as long as it is a sensor that can detect the touched position, the detection method is not limited, and examples include resistive film method, electrostatic capacitance coupling method, photo sensor method, ultrasonic method, Touch sensor panels of electromagnetic induction coupling method, surface acoustic wave method, etc. In terms of low cost, touch sensor panels of resistive film method and electrostatic capacitance coupling method can be preferably used.

An example of a resistive film type touch sensor panel includes a pair of substrates arranged facing each other, an insulating spacer sandwiched between the pair of substrates, and a resistive film provided on the inner front surface of each substrate Transparent conductive film, and touch position detection circuit. In an image display device provided with a resistive film type touch sensor panel, if the surface of the front panel is touched, the opposing resistive films are short-circuited, and current flows through the resistive film. The touch position detection circuit detects the voltage change at this time, thereby detecting the touched position.

An example of the touch sensor panel of the capacitive coupling method includes a substrate, a transparent electrode for position detection provided on the entire surface of the substrate, and a touch position detection circuit. In an image display device provided with a touch sensor panel of an electrostatic capacitance coupling method, if the surface of the front panel is touched, the transparent electrode is grounded via the electrostatic capacitance of the human body at the touched point. The touch position detection circuit detects the grounding of the transparent electrode, thereby detecting the touched position.

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

＜The plate-shaped body that can transmit light＞ In the present invention, a plate-shaped body capable of transmitting light can be used as the back plate. For example, a plate-shaped body (resin plate, resin sheet, resin film, glass plate, glass film, etc.) that can be used as a front surface plate can be used as the A plate-shaped body that transmits light.

The thickness of the plate-shaped body capable of transmitting light may be, for example, 5 μm or more and 2000 μm or less, preferably 10 μm or more and 1000 μm or less, and more preferably 15 μm or more and 500 μm or less. The plate-shaped body capable of transmitting light may include only one layer, and may include two or more layers.

Based on the above, as the order of the layering of the components in the display device, for example, front surface plate/adhesive layer/circular polarizing plate/isolation film, front surface plate/adhesive layer/circular polarizing plate/organic EL display Components, front surface plate/adhesive layer/circular polarizer/touch sensor panel/organic EL display element, etc.

The display device according to one embodiment of the present invention can be used as mobile devices such as smart phones, input panels, televisions, digital photo frames, electronic signs, measuring devices, meters, office equipment, medical equipment, and computers. Equipment, etc. [Example]

Hereinafter, the present invention will be explained in more detail with examples, but the present invention is not limited by these examples. In this embodiment, when the terms "%" and "parts" are used for description, these terms refer to mass% and mass parts unless otherwise specified.

[test methods] The measurement method and calculation method of each physical property value (weight average molecular weight, compression recovery rate, etc.) used in this example are as follows.

<Measurement of weight average molecular weight (Mw)> The weight average molecular weight (Mw) of (meth)acrylic polymer A is the number average molecular weight (Mn) in terms of polystyrene. Tetrahydrofuran is used in the mobile phase, and the following particle size sieve chromatography (size exclusion chromatography, SEC).

Specifically, the (meth)acrylic polymer A as the object to be measured was dissolved in tetrahydrofuran at a concentration of about 0.05% by mass, and 10 μL was injected into a size exclusion chromatograph (SEC) . The mobile phase flows at a flow rate of 1.0 mL/min. As the column, PLgel MIXED-B (manufactured by Polymer Laboratories) was used. The detector uses an ultraviolet-visible light detector (UV-VIS detector) (trade name: Agilent GPC).

<The thickness of the layer> The measurement was performed using a contact-type film thickness measuring device ("MS-5C" manufactured by Nikon Co., Ltd.). Among them, the polarizer and the retardation layer were measured using a laser microscope (“OLS3000” manufactured by Olympus Co., Ltd.).

＜Compression recovery rate of laminated body＞ By using the following evaluation equipment and evaluation conditions, B (%), which is the compression recovery rate of the laminate, was obtained. Specifically, first, a super cutter was used to cut a test piece with a length of 50 mm and a width of 50 mm from a laminate having a thickness of A (μm). Next, as shown in Fig. 2, at the center of the surface on the front plate side of the test piece, a ball indenter Z (Ball indenter) with a diameter of 0.4 mm was moved from the surface to the laminate with a force of 100 mN. The inside of the dent is pressed for 60 seconds to form a depression (recess), and the maximum depth x of the depression is determined. Furthermore, after 60 seconds from the time when the spherical indenter Z was removed from the laminate, the depth y of the recessed portion of the recess was obtained. Finally, B (%) is calculated by calculating the depth y of the restored depression/the maximum depth x×100. In addition, A (μm), which is the thickness of the laminate, can be obtained by the contact type film thickness measuring device described above.

Evaluation device: Nano Indenter Evaluation conditions: International Standardization Organization-Final Draft International Standard (ISO-FDIS) 14577-1 2013 (E), using a ball indenter with a diameter of 0.4 mm (Ball indenter) Evaluation temperature: 25℃ Force: 100 mN Pressing time: 60 seconds Standby time after removing the indenter: 60 seconds Creeping: 5 seconds.

＜Gel fraction of adhesive layer＞ The gel fraction of the adhesive layer (the adhesive layer A11 and the adhesive layer A12 described later) was measured in accordance with the following (I) to (V). (I) An adhesive layer having an area of about 8 cm×about 8 cm is bonded to a metal mesh (the mass is set to Wm) including stainless steel (SUS) 304 of about 10 cm×about 10 cm. (II) Weigh the mass of the paste obtained from (I), set its mass as Ws, and then fold it 4 times with an adhesive layer, and then weigh it with a stapler (stapler). , And set its mass to Wb. (III) Put the net nailed with a stapler in the above (II) into a glass container, add 60 mL of ethyl acetate and soak, and store the glass container at room temperature for 3 days. (IV) The net of (III) is taken out of the glass container, dried at 120°C for 24 hours, and then weighed, and its mass is set to Wa. (V) Substitute the weighed mass into the formula of gel fraction (mass%)=[{Wa-(Wb-Ws)-Wm}/(Ws-Wm)]×100 to calculate the adhesive layer The gel fraction.

[Manufacture of Adhesive Sheet] [1] Manufacturing of adhesive sheet A11 (1) Preparation of (meth)acrylic polymer A A mixed solution of 81.8 parts by mass of acetone, 98.6 parts by mass of butyl acrylate, 1.0 part by mass of 2-hydroxyethyl acrylate, and 0.4 part by mass of acrylic acid was charged into a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirrer, and nitrogen was used. The air in the container was replaced with no oxygen, and the internal temperature was increased to 55°C. After that, the total amount of the solution obtained by dissolving 0.14 parts by mass of azobisisobutyronitrile (polymerization initiator) in 10 parts by mass of acetone was added. One hour after the addition of the polymerization initiator, acetone was continuously added to the reaction vessel at an addition rate of 17.3 parts by mass/hour so that the concentration of the acrylic resin other than the monomer was 35% by mass, while the internal temperature The temperature was kept at 54°C to 56°C for 12 hours, and finally acetone was added to adjust the acrylic resin concentration to 20% by mass. The weight average molecular weight Mw of the obtained acrylic resin in terms of polystyrene by GPC was 1,270,000. This is referred to as (meth)acrylic polymer A. The (meth)acrylic polymer A has a structural unit derived from a hydroxyl group-containing unsaturated monomer, namely 2-hydroxyethyl acrylate, of 1% by mass, and is derived from a carboxyl group-containing unsaturated monomer, namely acrylic acid. The unit is 0.4% by mass.

(2) Preparation of adhesive composition A11 100 parts by mass (solid content conversion value; the same below) obtained in the above step (meth)acrylic polymer A, as the thermal crosslinking agent B polyisocyanate (manufactured by Tosoh Co., Ltd., product name " Coronate L") and 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM403") as silane coupling agent C, mix, stir well, and By diluting with methyl ethyl ketone, a coating solution of the adhesive composition A11 was obtained. Table 1 shows each formulation (solid content conversion value) of the adhesive composition A11 when the (meth)acrylic polymer is set to 100 parts by mass (solid content conversion value). In Table 1, the abbreviation "BA" means n-butyl acrylate, "2HEA" means 2-hydroxyethyl acrylate, and "AA" means acrylic acid. The Tg (°C) of these BA, 2HEA, and AA was obtained by differential thermal analysis (DTA).

(3) Manufacture of adhesive sheet A11 The coating solution of the adhesive composition A11 was applied to the release treatment surface of the first release film (manufactured by Lintec Co., Ltd., product name "SP-PET752150") using a knife coater, This forms a coating. The coating was heat-treated at 90°C for 1 minute, thereby forming a coating layer. Then, the coating layer on the first release isolation film and the second release film (manufactured by Lintec Co., Ltd., product The name "SP-PET382120") was bonded and cured at 23°C and 50%RH for 7 days to produce an adhesive sheet A11 having an adhesive layer with a thickness of 20 μm formed using the adhesive composition A11, that is, Adhesive sheet A11 including a first release film/adhesive layer (thickness: 20 μm)/second release film. In this embodiment, the adhesive layer formed by the adhesive sheet A11 is also referred to as the adhesive layer A11.

[2] Manufacturing of adhesive sheet A12 (1) Preparation of (meth)acrylic polymer A The (meth)acrylic polymer A used in the production of the pressure-sensitive adhesive sheet A11 is prepared.

(2) Preparation of adhesive composition A12 With respect to 100 parts by mass of the (meth)acrylic polymer A, the blending amount of Coronate L as a thermal crosslinking agent was set as shown in Table 1. Otherwise, set as The preparation method of the adhesive composition A11 is the same as that of the adhesive composition A11, thereby obtaining a coating solution of the adhesive composition A12.

(3) Manufacture of adhesive sheet A12 The coating solution using the adhesive composition A12 is set to be the same as the production process of the adhesive sheet A11, thereby producing the adhesive sheet A12. Among them, the adhesive sheet A12 has a structure including a first release film/adhesive layer (thickness: 25 μm)/second release film. In this embodiment, the adhesive layer formed by the adhesive sheet A12 is also referred to as the adhesive layer A12.

Table 1 shows each formulation (solid content conversion value) of the adhesive composition A11 and the adhesive composition A12 when the (meth)acrylic polymer A is set to 100 parts by mass (solid content conversion value). Table 1 also shows the values of the gel fractions of the adhesive layer A11 and the adhesive layer A12 obtained by the method described above.

[Table 1] (Meth) acrylic polymer A (parts by mass) Thermal crosslinking agent B SC agent C characteristic Single body composition (parts by mass) Molecular weight (Mw) Coronate L (parts by mass) KBM-403 (parts by mass) Gel fraction (mass%) BA 2HEA AA total Tg (℃) -54 -15 105 A11 98.6 1 0.4 100 1.27 million 0.4 0.5 70 A12 98.6 1 0.4 100 1.27 million 0.3 0.5 66

Furthermore, as commercially available adhesive sheets, CEF3005 and CEF3006 (both manufactured by 3M in the United States) were prepared. CEF3005 is a structure including a first release film/adhesive layer (thickness: 125 μm)/second release film, and CEF3006 is a structure including a first release film/adhesive layer (thickness: 150 μm)/second release film.

[Example 1] [Preparation of the components constituting the laminate] ＜Preparation of front surface plate (window film)＞ As the front surface plate, a polyimide film (thickness 40 μm) with a hard coat layer (thickness 10 μm) on one side was prepared. Therefore, the thickness of the front surface plate is 50 μm.

＜Preparation of circular polarizing plate＞ Coat the alignment film composition on one side of a 25 μm-thick triacetyl cellulose (TAC) film (manufactured by Konica Minolta Co., Ltd.), dry and irradiate it with polarized UV to form Optical alignment film. A composition containing a dichroic dye and a polymerizable liquid crystal compound is coated on the photo-alignment film, and after drying, the polymerizable liquid crystal compound is cured by ultraviolet irradiation to form a polarizer (thickness 2.5 μm). On the surface of the polarizer opposite to the TAC film side, a protective layer composition containing polyvinyl alcohol and water was coated and dried to form a protective layer (thickness 1 μm). In this way, a linear polarizing plate is obtained.

The λ/4 layer side of the retardation film described later was bonded to the protective layer of the linear polarizing plate to obtain a circular polarizing plate. The retardation film has a thickness of 15 μm, and has a structure in which an adhesive layer, a λ/4 layer, an adhesive layer, and a positive C layer are sequentially laminated. The thickness of the adhesive layer is 5 μm. The λ/4 layer has a layer formed by curing a liquid crystal compound and an alignment film, and has a thickness of 2 μm. The positive C layer has a layer formed by curing a liquid crystal compound and an alignment film, and has a thickness of 3 μm. In this way, a circular polarizing plate (100 mm in length×100 mm in width) having a layer structure of "TAC film/photoalignment film/polarizer/protective layer/phase difference film" was prepared.

[Manufacturing of laminated body] The laminated body was manufactured in the following procedure. First, after corona treatment (output 0.3 kW, treatment speed 3 m/min) was performed on one of the front surface plates and the surface of the adhesive sheet A12 from which the first release film was peeled, the corona treated surfaces were bonded to each other. Furthermore, the surface of the adhesive sheet A12 exposed by peeling the second release film and the surface of the circular polarizer on the side of the linear polarizer (the surface of the TAC film) are corona treated, and the corona treated surfaces are bonded to each other, In this way, the laminate of Example 1 was produced. The laminate of Example 1 has a shape of 119 μm in thickness, 100 mm in length and 100 mm in width.

[Example 2 to Example 4 and Comparative Example 1 to Comparative Example 4] Except for changing the type and thickness of the adhesive layer, and the thickness of the laminate as shown in Table 2, the same procedure as in Example 1 was used to prepare Examples 2 to 4 and Comparative Example 1. -The laminate of Comparative Example 4.

Regarding the laminates of Examples 1 to 4 and Comparative Examples 1 to 4, the thickness and type of the adhesive layer, the thickness of the laminate, the compression recovery rate obtained by the method described above, And the numerical value of compression recovery rate/thickness (B/A) of a laminated body, etc. are shown in Table 2 as a list.

[Table 2] Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Adhesive layer thickness (μm) 25 20 50 40 100 125 150 50 Type of adhesive layer (type of adhesive sheet) A12 A11 A12 (two-piece stack) A11 (two-piece layered) A11 (Five-layer stacking) CEF3005 CEF3006 A12 (two-piece stack) Layer thickness of laminate (μm) 119 114 144 134 194 219 244 154 Compression recovery rate (%) 98.1 98.3 98.7 99.1 98.6 98.2 98.4 90.1 Compression recovery rate/layer thickness of laminate (%/μm) 0.82 0.86 0.68 0.74 0.51 0.45 0.4 0.58

Furthermore, with respect to the laminates of Examples 1 to 4 and Comparative Examples 1 to 4, a wet heat bending durability test and a surface hardness test were performed by the method described later. The results are shown in Table 3.

＜Damp heat bending durability test＞ First, a super cutter was used to cut a test piece with a length of 100 mm and a width of 10 mm from the laminate of each example and each comparative example. Next, the test piece was left in a humid and hot environment of 60° C./90% RH for 24 hours. The test pieces (laminated body) exposed to the hot and humid environment are wound around a cylindrical mandrel (made of iron) with the front surface plate on the inside, thereby bending the test pieces in the longitudinal direction The damp heat bending durability test. From this, the minimum diameter of the mandrel that does not generate cracks, cracks, etc. on the surface of the front surface plate of the test piece (layered body) and air bubbles in the adhesive layer was determined, and the classification was performed based on the following criteria. In the wet heat bending durability test, the smaller the value of the minimum diameter, the better the wet heat bending durability of the laminate can be evaluated. S: When wound on a mandrel with a diameter (ϕ) less than 5 mm, cracks are generated on the front surface plate and bubbles are generated in the adhesive layer A: When wound on a mandrel over ϕ5 mm and less than ϕ10 mm, cracks are generated in the front surface plate and bubbles are generated in the adhesive layer B: When wound on a mandrel that exceeds ϕ10 mm and ϕ15 mm or less, cracks are generated in the front surface plate and air bubbles are generated in the adhesive layer C: When wound on a mandrel that exceeds ϕ 15 mm and ϕ 20 mm or less, cracks are generated in the front surface plate and bubbles are generated in the adhesive layer D: When wound on a mandrel exceeding ϕ20 mm, cracks are generated in the front surface plate and air bubbles are generated in the adhesive layer.

＜Surface hardness test＞ On the surface of the front surface plate of the laminate of each example and each comparative example, a pencil hardness tester (PHT, manufactured by SUKBO SCIENCE) was used at a temperature of 25°C by applying 100 g of A pencil in a loaded state (manufactured by Mitsubishi Pencil Co., Ltd., core hardness is 6B), a trace of recesses is formed on the surface. In this case, the time until the trace of the recessed portion disappeared was determined, and the classification was performed based on the following criteria to evaluate the surface hardness of the laminate of each Example and each Comparative Example. In this surface hardness test, the shorter the time until the traces of the recesses disappear, it can be evaluated that the surface hardness is more excellent. A: The dent marks disappeared in less than 30 minutes B: More than 30 minutes and less than 60 minutes, the dent marks disappeared C: The dent marks disappeared for more than 60 minutes and less than 90 minutes D: Even after 90 minutes, the dent marks did not disappear.

[table 3] Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Damp heat bending durability test S S A A D D D D Surface hardness test A A B B D D D D

According to the above, the wet heat bending durability and surface hardness of Examples 1 to 4 satisfying the relationship of 0.6≦B/A≦2 relative to Comparative Example 1 to Comparative Example 4 having the relationship of B/A<0.6 Both are excellent.

10: Front panel 11: Hard coating 12: Resin film 20: Adhesive layer 30: Circular polarizer 100: layered body B: Compression recovery rate x: maximum depth y: Depth of the restored depression Z: spherical indenter

Fig. 1 is a schematic cross-sectional view showing an example of the laminate of the present invention. FIG. 2 is an explanatory diagram explaining a method of obtaining the compression recovery rate (B (%)) of the laminate of the present invention.

10: Front panel

11: Hard coating

12: Resin film

20: Adhesive layer

30: Circular polarizer

100: layered body

Claims (8)

A laminated body comprising: a front surface plate; a circular polarizing plate; and an adhesive layer between the front surface plate and the circular polarizing plate, wherein: When the thickness of the laminate is A (μm) and the compression recovery rate of the laminate is B (%), the laminate satisfies the relationship of 0.6≦B/A≦2, and The B (%) is obtained by pressing a spherical indenter with a diameter of 0.4 mm from the surface of the laminate body on the front surface plate side into the interior of the laminate body with a force of 100 mN for 60 seconds. When a depression is formed, the ratio (%) of the depth of the depression recovered when the spherical indenter is removed from the laminate to the maximum depth of the depression formed. The laminate according to claim 1, wherein the A (μm) of the laminate is 150 μm or less. The laminate according to claim 1 or 2, wherein the circularly polarizing plate includes any one of a film formed of a liquid crystal layer or a polyvinyl alcohol-based resin film. The laminate according to any one of claims 1 to 3, wherein the front surface plate is a resin film or a hard coat resin film having a hard coat on at least one surface of the resin film Of any kind. A display device comprising the laminate according to any one of claim 1 to claim 4. The display device according to claim 5, wherein the display device further includes a back panel, and The back plate is laminated on the circularly polarizing plate side of the laminated body. The display device according to claim 6, wherein the back panel is a touch sensor panel. The display device according to any one of claims 5 to 7, which is capable of bending the front surface plate side on the inner side.

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