KR20210128397A - Laminate, pressure-sensitive adhesive layer and pressure-sensitive adhesive sheet - Google Patents

Abstract

Provided is a laminate excellent in flexibility at low temperatures and durability in a moist heat environment. A laminate comprising a front plate, a pressure-sensitive adhesive layer, and a rear plate in this order, wherein the pressure-sensitive adhesive layer includes a (meth)acrylic polymer, a (meth)acrylate monomer having a difunctional or higher function having an aliphatic urethane group in the molecule, or an oligomer thereof, and Formed from a pressure-sensitive adhesive composition containing a photopolymerization initiator, the pressure-sensitive adhesive layer, the storage elastic modulus (G') at -40 ° C. 5 × 10 ³ Pa or more and 1 × 10 ⁵ Pa or less, the laminate.

Description

Laminate, pressure-sensitive adhesive layer and pressure-sensitive adhesive sheet

The present invention relates to a laminate, an adhesive layer, and an adhesive sheet.

It is known to use the adhesive film which has an adhesive layer comprised from an adhesive composition for a display apparatus (patent documents 1-2).

Korean Patent No. 10-2018-0013067 Korean Patent No. 10-2016-0053736

When the laminated body used for a display apparatus was bent at low temperature, a crack may generate|occur|produce in an adhesive layer. Moreover, the improvement of the durability in a wet heat environment is also calculated|required of an adhesive layer.

An object of the present invention is to provide a laminate, a pressure-sensitive adhesive layer, and a pressure-sensitive adhesive sheet that are excellent in flexibility under low temperature and durability in a moist heat environment.

MEANS TO SOLVE THE PROBLEM This invention provides the following laminated body, an adhesive layer, and an adhesive sheet.

[1] A laminate comprising a front plate, an adhesive layer, and a back plate in this order,

The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer, a (meth)acrylate monomer or oligomer thereof having a difunctional or higher having an aliphatic urethane group in the molecule, and a photopolymerization initiator,

The said adhesive layer is a laminated body whose storage elastic modulus (G') at -40 ^{degreeC is 5x10 3} Pa or more and 1x10 ⁵ Pa or less.

[2] The laminate according to [1], wherein the back plate includes at least one selected from the group consisting of a polarizer layer and a touch sensor panel.

[3] A display device comprising the laminate according to [1] or [2].

[4] A pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition,

The pressure-sensitive adhesive composition contains a (meth)acrylic polymer, a (meth)acrylate monomer or oligomer thereof having a difunctional or higher function having an aliphatic urethane group in the molecule, and a photopolymerization initiator,

The pressure-sensitive adhesive layer has a storage elastic modulus (G') at -40°C of 5×10 ³ Pa or more and 1×10 ⁵ Pa or less, the pressure-sensitive adhesive layer.

[5] A pressure-sensitive adhesive sheet comprising a substrate and the pressure-sensitive adhesive layer according to [4], which is formed on the substrate.

ADVANTAGE OF THE INVENTION According to this invention, the laminated body, the adhesive layer, and the adhesive sheet excellent in the flexibility at the time of low temperature and durability in a wet heat environment can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows an example of the laminated body which concerns on this invention.
2 is a schematic cross-sectional view showing another example of the laminate according to the present invention.
3 is a schematic diagram illustrating a method of a flexibility test.

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

<Laminate>

The present invention relates to a laminate including a front plate, an adhesive layer, and a back plate in this order. In the laminate according to an aspect of the present invention, the rear plate preferably includes at least one selected from the group consisting of a polarizer layer and a touch sensor panel. Since the laminated body which concerns on this invention is excellent in the flexibility at the time of low temperature and durability in a wet heat environment, it is suitable as a material used for a display apparatus etc.

A schematic cross-sectional view of a laminate according to an aspect of the present invention is shown in FIG. 1 . In FIG. 1 , the laminate 100 includes a front plate 101 , a first adhesive layer 102 as an adhesive layer, and a back plate in this order.

In the example shown in FIG. 1, a back plate contains the polarizer layer 103, the bonding layer 104, and the plate-shaped object 105 in this order. The polarizer layer 103 will be described later. The bonding layer 104 can be formed from a conventionally well-known adhesive or adhesive agent, and can also be formed from the adhesive composition like the 1st adhesive layer 102.

The thickness of the laminate 100 is not particularly limited because it varies depending on the function required for the laminate and the use of the laminate, but is, for example, 50 µm or more and 4000 µm or less, preferably 100 µm or more and 2000 µm or less. , more preferably 150 µm or more and 1000 µm or less.

The planar view shape of the laminate 100 may be, for example, a rectangular shape, preferably a rectangular shape having a long side and a short side, and more preferably a rectangular shape. When the shape of the surface direction of the laminated body 100 is a rectangle, the length of the long side may be 10 mm or more and 1400 mm or less, for example, Preferably they are 50 mm or more and 600 mm or less. The length of the short side is, 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. As for each layer which comprises a laminated body, each part may be R-processed, an edge part may be notched, or the perforation process may be carried out.

The laminate 100 can be used, for example, in 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 display device may have a touch panel function.

[Front panel]

The front plate 101 is not limited in material and thickness as long as it is a plate-like body capable of transmitting light, and may be composed of only one layer or may be composed of two or more layers. As the example, a resin plate-shaped object (for example, a resin plate, a resin sheet, a resin film, etc.), a glass-made plate-shaped object (for example, a glass plate, a glass film, etc.), and the touch sensor panel mentioned later are mentioned. The front plate 101 may be a layer disposed on the outermost surface of the display device.

The thickness of the front plate 101 may be, for example, 10 µm or more and 500 µm or less, preferably 20 µm or more and 200 µm or less, and more preferably 30 µm or more and 100 µm or less. In this invention, the thickness of each layer, such as a front plate, a 1st adhesive layer, and a back plate, can be measured according to the thickness measuring method demonstrated in the Example mentioned later.

When the front plate 101 is a resin plate, the resin plate is not limited as long as it can transmit light. Examples of the resin constituting the resin-made plate-like body such as a resin film include triacetyl cellulose, acetyl cellulose butyrate, ethylene-vinyl acetate copolymer, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, polyester, Polystyrene, polyamide, polyetherimide, poly(meth)acrylic, polyimide, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal , polyether ketone, polyether ether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, a film formed of a polymer such as polyamideimide. . These polymer|macromolecules can be used individually or in mixture of 2 or more types. As said resin, from a viewpoint of improving intensity|strength and transparency, Preferably, the film formed from polymer|macromolecule, such as polyimide, polyamide, and polyamideimide, is mentioned. The thickness of the resin-made plate may be, for example, 10 µm or more and 500 µm or less, preferably 20 µm or more and 200 µm or less, more preferably 30 µm or more and 150 µm or less, and may be 100 µm or less.

From the viewpoint of hardness, the front plate 101 is a film in which a hard coat layer is preferably provided on at least one surface of the base film. As a base film, the film which consists of the said resin can be used. The hard-coat layer may be formed in one surface of a base film, and may be formed in both surfaces. By providing a hard-coat layer, it can be set as the resin film which improved hardness and scratch property. The hard coat layer is, for example, a cured layer of ultraviolet curable resin. Examples of the ultraviolet curable resin include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. The hard-coat layer may contain the additive in order to improve intensity|strength. The additive is not limited, and inorganic fine particles, organic fine particles, or a mixture thereof may be mentioned.

When the front plate 101 is a glass plate, the tempered glass for a display is used preferably as a glass plate. The thickness of a glass plate may be 10 micrometers or more and 500 micrometers or less, for example. By using a glass plate, the front plate 101 which has excellent mechanical strength and surface hardness can be comprised.

When the laminate 100 is used in a display device, the front plate 101 not only has a function (function as a window film) to protect the front surface (screen) of the display device, but also functions as a touch sensor, blue light cut What has a function, a viewing angle adjustment function, etc. may be sufficient.

[Adhesive Layer (First Adhesive Layer)]

The pressure-sensitive adhesive layer (the first pressure-sensitive adhesive layer 102) is formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer, a (meth)acrylate monomer or oligomer thereof having a difunctional or higher function having an aliphatic urethane group in the molecule, and a photopolymerization initiator. The pressure-sensitive adhesive layer has a storage elastic modulus (G') at -40°C of 5×10 ³ Pa or more and 1×10 ⁵ Pa or less. The pressure-sensitive adhesive layer is applied as the first pressure-sensitive adhesive layer 102 in the laminate 100 of FIG. 1 . An adhesive layer may be applied as the bonding layer 104 in the laminated body 100 of FIG.

The first pressure-sensitive adhesive layer 102 is interposed between the front plate 101 and the rear plate (such as a laminate of the polarizer layer 103 or the polarizer layer 103 and the plate-shaped body 105) and is a layer for bonding them together, For example, the layer comprised with an adhesive, or the layer formed by performing any process with respect to the said layer may be sufficient. The first pressure-sensitive adhesive layer 102 may be a pressure-sensitive adhesive layer disposed at a position closest to the front plate among the pressure-sensitive adhesive layers constituting the laminate 100 . In this specification, "adhesive" is also called a pressure-sensitive adhesive. In this specification, an "adhesive" refers to adhesives other than an adhesive (pressure-sensitive adhesive), and is clearly distinguished from an adhesive. One layer may be sufficient as the 1st adhesive layer 102, Although what consists of two or more layers may be sufficient as it, Preferably it is one layer.

It is preferable that the thickness of the 1st adhesive layer 102 is 3 micrometers or more and 100 micrometers or less, for example, It is more preferable that they are 5 micrometers or more and 50 micrometers or less, 20 micrometers or more may be sufficient.

(Composition of the first pressure-sensitive adhesive layer (adhesive composition))

As described above, the first pressure-sensitive adhesive layer 102 is a (meth)acrylic polymer, a (meth)acrylate monomer or oligomer thereof having a bifunctional or higher function having an aliphatic urethane group in the molecule, and a pressure-sensitive adhesive composition containing a photopolymerization initiator (hereinafter, “ It is formed from adhesive composition A").

The said adhesive composition A contains a (meth)acrylic-type polymer from a viewpoint of the suppression of generation|occurrence|production of the crack at the time of low temperature, and the improvement of durability in a moist heat environment. The pressure-sensitive adhesive composition A may be an active energy ray-curable type. In this specification, "(meth)acrylic polymer" means at least 1 sort(s) selected from the group which consists of an acryl-type polymer and a methacryl-type polymer. The same applies to other terms appended with "(meta)".

Herein, the active energy ray-curable pressure-sensitive adhesive composition has a property of being cured by irradiation with active energy rays such as ultraviolet rays or electron beams, so that even before active energy ray irradiation, it has adhesiveness and can adhere to an adherend such as a film, and It refers to the pressure-sensitive adhesive composition having a property that can be cured by irradiation with an active energy ray, such as adhesive strength. The pressure-sensitive adhesive composition A is an active energy ray-curable pressure-sensitive adhesive composition, and is preferably an ultraviolet curing type.

The (meth)acrylic polymer (hereinafter also referred to as "(meth)acrylic polymer A") contained in the pressure-sensitive adhesive composition A has a structural unit derived from a monomer having a polar functional group other than a (meth)acryloyl group is the total mass of the polymer It is preferable that it is less than 5 mass % on the basis of. As a polar functional group other than a (meth)acryloyl group, a hydroxyl group, a carboxy group, an amino group, an amide group, an epoxy group, etc. are mentioned, for example. Thereby, the flexibility of an adhesive layer improves and it exists in the tendency which becomes easy to suppress generation|occurrence|production of the crack of the adhesive layer at the time of low temperature. The (meth)acrylic polymer A, from the viewpoint of suppressing the occurrence of cracks at low temperatures, preferably, a structural unit derived from a monomer having a polar functional group other than a (meth)acryloyl group is based on the total mass of the polymer It is 1 mass % or less, More preferably, it is 0.01 mass % or less, More preferably, it does not have the structural unit derived from the monomer which has polar functional groups other than a (meth)acryloyl group. It is preferable that the (meth)acrylic polymer A itself does not also have a hydroxyl group, a carboxy group, an amino group, an amide group, and an epoxy group.

The (meth)acrylic polymer A can contain the structural unit derived from the (meth)acrylic-type monomer which has a linear or branched C1-C24 alkyl group. As a (meth)acrylic-type monomer which has a linear or branched C1-C24 alkyl group, (meth)acrylic acid ester etc. may be sufficient, for example, As the example, (meth)acrylate butyl, (meth)methyl acrylate , (meth) ethyl acrylate, (meth) acrylate hexyl, (meth) acrylate octyl, (meth) acrylate lauryl, (meth) acrylate isooctyl, (meth) acrylate isodecyl, (meth) acrylate 2-ethylhexyl, ( isobornyl meth)acrylate, and the like. The (meth)acrylic polymer A may be a polymer or copolymer which uses 1 type(s) or 2 or more types of the said (meth)acrylic acid ester as a monomer. Content of the (meth)acrylic-type polymer A in the adhesive composition A may be 50 mass % or more and 100 mass % or less on the basis of the total mass % of solid content of the adhesive composition A, for example, Preferably 80 mass % or more and 99.5 mass % It is below, More preferably, they are 90 mass % or more and 99 mass % or less, More preferably, they are 95 mass % or more and 98 mass % or less.

The weight average molecular weights (Mw) of the (meth)acrylic polymer A may be, for example, 300,000 or more and 700,000 or less, and from a flexible viewpoint, Preferably they are 300,000 or more and 600,000 or less. A weight average molecular weight (Mw) can be measured according to the measuring method demonstrated in the Example mentioned later.

The adhesive composition A may contain the (meth)acrylic-type polymer A 1 type, or 2 or more types. The adhesive composition A may contain the (meth)acrylic-type polymer A as the structural component, and may contain a crosslinking agent further. Examples of the crosslinking agent include those that form a metal carboxylate salt between a carboxyl group and a divalent or higher metal ion; A polyamine compound that forms an amide bond with a carboxy group; A polyepoxy compound or polyol, which forms an ester bond with a carboxy group; As a polyisocyanate compound, what forms an amide bond between a carboxy group, etc. are mentioned. Especially, a polyisocyanate compound is preferable. When the adhesive composition A contains a crosslinking agent, content of a crosslinking agent may be 5 mass parts or less with respect to (meth)acrylic-type polymer A100 mass parts (solid content) in conversion of solid content, For example, Preferably, 1 mass part or less , More preferably, it is 0.5 mass part or less, More preferably, it is 0.1 mass part or less. It is most preferable that the adhesive composition A does not contain a crosslinking agent.

In addition to the (meth)acrylic polymer A, the adhesive composition A contains the (meth)acrylate monomer more than bifunctional which has an aliphatic urethane group in a molecule|numerator, or its oligomer from a viewpoint of showing favorable flexibility at the time of low temperature. The "aliphatic urethane group" in the bifunctional or higher (meth)acrylate monomer having an aliphatic urethane group in the molecule or an oligomer thereof means, in the molecule of the (meth)acrylate monomer or the oligomer, a urethane group and an aliphatic hydrocarbon group, respectively. It means that they are included separately.

When the adhesive composition A contains the (meth)acrylate oligomer more than bifunctional which has an aliphatic urethane group in a molecule|numerator, it is preferable that the weight average molecular weight (Mw) of the oligomer is 500 or more and 20000 or less. Examples of the bifunctional or higher (meth)acrylate monomer having an aliphatic urethane group in the molecule or an oligomer thereof include UF-8001G (Kyoei Chemical Co., Ltd.), Miramer PU2560, Miramer PU2100 (all Miwon Specialty Chemicals), etc. can be heard The monomer or oligomer thereof may be bifunctional or more functional, and may be trifunctional, tetrafunctional, hexafunctional, 9 functional, 10 functional, 15 functional, and the like. Examples of such a compound include Miramer PU340, Miramer PU610, Miramer MU9800, Miramer MU9500 (all manufactured by Miwon Speciality Chemical Company). The pressure-sensitive adhesive composition A may contain one or more bifunctional (meth)acrylate monomers or oligomers thereof having an aliphatic urethane group in the molecule.

Content of the (meth)acrylate monomer more than bifunctional which has an aliphatic urethane group in a molecule|numerator in adhesive composition A, or its oligomer is conversion of solid content, For example, with respect to the said (meth)acrylic-type polymer A 100 mass parts (solid content), 5 It can be set as 30 mass parts or more and 30 mass parts or more. By containing the monomer or its oligomer, flexibility is ensured by its linear structure and elasticity at low temperature tends to be easily maintained due to the urethane structure, so that good flexibility can be obtained at low temperature, and further described later It becomes possible to make storage elastic modulus G' into a predetermined range.

The pressure-sensitive adhesive composition A further contains a photoinitiator. The pressure-sensitive adhesive composition A may further contain an active energy ray polymerizable compound, a photosensitizer, etc. other than the (meth)acrylic polymer A, and a (meth)acrylate monomer or oligomer thereof having a difunctional or higher function having an aliphatic urethane group in the molecule. have.

As a photoinitiator, benzyl dimethyl ketal, 1-hydroxycyclohexyl ketone, etc. are mentioned, for example. The pressure-sensitive adhesive composition A may contain one or two or more types of photoinitiators. Content of the photoinitiator in adhesive composition A can be 0.01 mass part or more and 1 mass part or less with respect to 100 mass parts (solid content) of said (meth)acrylic-type polymer A in conversion of solid content, for example.

The following compounds can be illustrated as active energy ray polymeric compounds other than the (meth)acrylic-type polymer A and the (meth)acrylate monomer more than bifunctional which has an aliphatic urethane group in a molecule|numerator, or its oligomer. For example, (meth)acrylate monomer which has at least 1 piece(s) acryloyloxy group in a molecule|numerator; (meth)acrylic compounds such as (meth)acryloyloxy group-containing compounds such as (meth)acrylate oligomers obtained by reacting two or more functional group-containing compounds and having at least two (meth)acryloyloxy groups in the molecule can be heard The pressure-sensitive adhesive composition A is a (meth)acrylic polymer A and an active energy ray-polymerizable compound other than the (meth)acrylate monomer or oligomer thereof having a difunctional or higher function having an aliphatic urethane group in the molecule, the total mass of the solid content of the pressure-sensitive adhesive composition A It may contain 0 mass % or more and 10 mass % or less on the basis of.

The pressure-sensitive adhesive composition A includes fine particles for imparting light scattering properties, beads (resin beads, glass beads, etc.), glass fibers, resins other than the base polymer, tackifiers, fillers (metal powders or other inorganic powders, etc.), antioxidants, It may contain additives such as ultraviolet absorbers, dyes, pigments, colorants, defoamers, and corrosion inhibitors. It is preferable that the adhesive composition A does not contain an organic solvent from a viewpoint of preventing the problem of the durability fall by a residual solvent.

An adhesive layer can be formed by apply|coating adhesive composition A on a base material. The adhesive layer formed on the base material becomes a hardened|cured material which has a desired degree of hardening by irradiating an active energy ray. As said base material, the peeling film etc. which were given a front plate, a back plate, and the release process mentioned later can be illustrated.

(Storage elastic modulus (G') of the first pressure-sensitive adhesive layer)

The first pressure-sensitive adhesive layer 102 has a storage elastic modulus (G') at -40°C of 5×10 ³ Pa or more and 1×10 ⁵ Pa or less. The storage elastic modulus (G') of the 1st adhesive layer 102 from a viewpoint of suppressing generation|occurrence|production of the crack at the time of low temperature is 1x10 ⁴ Pa or more, and it is preferable that they are ^{1x10 5 Pa or less.} About the storage elastic modulus (G') at -40 degreeC, it can measure according to the measuring method demonstrated in the Example mentioned later.

The laminate used for a display device WHEREIN: As one of the characteristics calculated|required of an adhesive layer, there exists a stress relaxation characteristic. However, even when it is excellent in a stress relaxation characteristic, a crack may generate|occur|produce in the adhesive layer due to the bending|flexion at the time of low temperature and high temperature. As a result of the study by the present inventors, when the storage elastic modulus (G') in -40 degreeC of an adhesive layer existed within the said range, it discovered that there existed a tendency for a stress relaxation characteristic to become easy to sustain at the time of low temperature. Thereby, even when bending repeatedly at low temperature, adhesiveness was maintained between an adhesive layer and the structural member of a laminated body, and it discovered that generation|occurrence|production of the crack of an adhesive layer could be suppressed by this.

Excellent flexibility at low temperature means that when bending so that the radius of curvature of the inner surface of the laminate 100 is 2.5 mm at -40°C in at least one direction in the surface of the laminate 100, the pressure-sensitive adhesive layer The absence of cracks means that it is confirmed by the naked eye. When the laminate 100 is repeatedly bent so that the radius of curvature of the inner surface of the laminate 100 is 2.5 mm at -40°C in at least one direction in the plane, cracks occur even if the number of bending is 50,000 times. It is preferable not to occur. In this specification, as a crack of an adhesive layer, events, such as a crack which arise in an adhesive layer, and peeling in between an adhesive layer and the structural member of a laminated body, shall be contained.

In the present specification, the bending includes a bent form in which a curved surface is formed in the curved portion. In the bent form, the bending radius of the bent inner surface is not particularly limited. In addition, the bending includes a form of refraction in which the refraction angle of the inner surface is greater than 0 degrees and less than 180 degrees, and also includes a folding form in which the bending radius of the inner surface is close to zero or the refraction angle of the inner surface is 0 degrees.

The laminate 100, when the storage elastic modulus (G') at -40 ° C of the first pressure-sensitive adhesive layer 102 is 5 × 10 ³ Pa or more and 1 × 10 ⁵ Pa or less, bending the front plate side inside Both (infold) and bending with the front plate side outward (outfold) are possible.

In the laminate 100, when the storage elastic modulus (G') at -40°C of the first pressure-sensitive adhesive layer 102 is 5×10 ³ Pa or more and 1×10 ⁵ Pa or less, at least one direction in the plane , When repeatedly bending at -40°C so that the bending radius of the inner surface of the laminate 100 becomes 2.5 mm, preferably, cracks do not occur even if the number of bending is 50,000 times. When the laminate 100 is repeatedly bent so that the radius of curvature of the inner surface of the laminate 100 is 2.5 mm at -40°C in at least one direction in the plane, more preferably, the number of bending is Cracks do not occur even when the number of bending is about 100,000 times, more preferably, no cracks occur even when the number of bending is about 150,000 times, and still more preferably, no cracks are generated even when the number of bending is about 200,000 times. It is preferable that the number of times of bending that does not cause cracks when the laminate 100 is subjected to repeated bending at -40°C in at least one direction and a direction orthogonal thereto in the plane is within the above range. A display device to which such a laminate 100 is applied can be used as a flexible display that can be bent or wound.

The method of setting the storage elastic modulus (G') at -40°C of the first pressure-sensitive adhesive layer 102 to 5 × 10 ³ Pa or more and 1 × 10 ⁵ Pa or less is not particularly limited, but, for example, the pressure-sensitive adhesive layer described above The method of forming from the adhesive composition A can be illustrated. In addition, a method of changing the type of the monomer constituting the (meth)acrylic polymer A, adjusting the molecular weight of the (meth)acrylic polymer A, or combining these may be exemplified.

[Backboard]

The laminate 100 includes a front plate 101 , a first pressure-sensitive adhesive layer 102 , and a rear plate in this order to be illustrated in FIG. 1 . In the example shown in FIG. 1, a back plate contains the polarizer layer 103, the bonding layer 104, and the plate-shaped object 105 in this order. Not limited to the example shown in FIG. 1, the laminate may have a form including a front plate, an adhesive layer, and a polarizer layer as a back plate in this order, and a touch sensor panel as a front plate, an adhesive layer, and a back plate may have a form including in this order.

Thus, it is preferable that a back plate contains at least 1 sort(s) selected from the group which consists of a polarizer layer and a touch sensor panel. A back plate can be set as a polarizer layer, a touch sensor panel, or another plate-shaped body, or can be set as these combinations. One layer may be sufficient as a back plate, or although what consists of two or more layers may be sufficient, Preferably it consists of multiple layers. The back plate can also contain the retardation layer mentioned later, the said bonding layer 104, etc. as a component used for a back board. The thickness of the back plate may be, for example, 10 µm or more and 2000 µm or less, and preferably 50 µm or more and 1000 µm or less.

(Polarizer layer)

The present invention can include a polarizer layer 103 as a part of the rear plate, for example, as shown in FIG. 1 . As the polarizer layer 103, the stretched film or stretched layer to which the dichroic dye was adsorbed, the layer formed by apply|coating and hardening the composition containing a dichroic dye and a polymeric compound, etc. are mentioned. When a dye is dispersed and oriented in an anisotropic medium, it may appear colored in a certain direction and appear almost colorless in a direction perpendicular to it. A pigment showing this phenomenon is called a dichroic pigment. As a dichroic dye, iodine, a dichroic organic dye, etc. are specifically used. The dichroic organic dye includes a dichroic direct dye composed of a disazo compound such as C.I.DIRECT RED 39 and a dichroic direct dye composed of a compound such as trisazo and tetrakisazo.

The thickness of the polarizer layer 103 is 2 micrometers or more and 40 micrometers or less, for example. The thickness of the polarizer layer 103 may be 5 µm or more, 20 µm or less, 15 µm or less, and further 10 µm or less.

-Stretched film or stretched layer, the polarizer layer-

The polarizer layer, which is a stretched film to which a dichroic dye is adsorbed, is usually a step of uniaxially stretching a polyvinyl alcohol-based resin film, dyeing a polyvinyl alcohol-based resin film with a dichroic dye, a step of adsorbing the dichroic dye, It can manufacture through the process of treating the polyvinyl alcohol-type resin film to which the dichroic dye has adsorbed with the aqueous boric acid solution, and the process of washing with water after the process with the aqueous boric acid solution.

Polyvinyl alcohol-type resin can be obtained by saponifying polyvinyl acetate-type resin. As polyvinyl acetate-type resin, the copolymer of vinyl acetate and other monomer copolymerizable to it other than polyvinyl acetate which is a homopolymer of vinyl acetate is 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 polyvinyl alcohol-type resin is about 85 mol% or more and 100 mol% or less normally, Preferably it is 98 mol% or more. The polyvinyl alcohol-based resin may be modified, for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can be used. The polymerization degree of polyvinyl alcohol-type resin is 1000 or more and 10000 or less normally, Preferably they are 1500 or more and 5000 or less.

The polarizer layer, which is a stretched layer to which the dichroic dye is adsorbed, is usually a process of applying a coating liquid containing the polyvinyl alcohol-based resin on a base film, a process of uniaxially stretching the obtained laminated film, a uniaxially stretched laminated film By dyeing the polyvinyl alcohol-based resin layer with a dichroic dye, the dichroic dye is adsorbed to form a polarizer layer; It can be manufactured through the following process. A base film is peeled and removed from a polarizer layer as needed. The material and thickness of a base film may be the same as that of the thermoplastic resin film mentioned later and thickness.

The polarizer layer which is a stretched film or a stretched layer may be introduce|transduced into the laminated body in the form by which the thermoplastic resin film is bonded by the single side|surface or both surfaces. This thermoplastic resin film can function as a protective film for the polarizer layer 103 or retardation film. A thermoplastic resin film, For example, Polyolefin resins, such as chain|strand polyolefin resin (polypropylene resin etc.) and cyclic polyolefin resin (norbornene type resin etc.); Cellulose resins, such as a triacetyl cellulose; polyester-based resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate-based resin; (meth)acrylic resin; Alternatively, it may be a film made of a mixture thereof or the like.

The thickness of the thermoplastic resin film is usually 300 µm or less, preferably 200 µm or less, more preferably 100 µm or less, still more preferably 80 µm or less, and still more preferably 60 µm or less from the viewpoint of reducing the thickness of the thermoplastic resin film. It is micrometer or less, and is 5 micrometers or more normally, Preferably it is 20 micrometers or more.

The thermoplastic resin film may or may not have retardation. A thermoplastic resin film can be bonded to the polarizer layer 103 using an adhesive bond layer, for example.

-Polarizer layer formed by applying and curing a composition containing a dichroic dye and a polymerizable compound-

As a polarizer layer formed by coating and curing a composition containing a dichroic dye and a polymerizable compound, a composition containing a polymerizable dichroic dye having liquid crystallinity or a composition containing a dichroic dye and a polymerizable liquid crystal is applied to a base film The polarizer layer containing hardened|cured material of polymeric liquid crystal compounds, such as a layer obtained by apply|coating and hardening, is mentioned. The polarizer layer formed by apply|coating and hardening the composition containing a dichroic dye and a polymeric compound is preferable since there is no restriction|limiting in a bending direction compared with the stretched film or stretched layer to which the dichroic dye was adsorbed.

You may peel and remove the said base film from a polarizer layer as needed. The material and thickness of the base film may be the same as the material and thickness of the above-described thermoplastic resin film.

The polarizer layer formed by apply|coating and hardening the composition containing a dichroic dye and a polymeric compound may be introduce|transduced into the laminated body in the form by which the thermoplastic resin film is pasted together on the single side|surface or both surfaces. As a thermoplastic resin film, the thing similar to the thermoplastic resin film which can be used for a polarizer layer which is a stretched film or a stretched layer can be used. A thermoplastic resin film can be bonded to a polarizer layer using an adhesive bond layer, for example.

The thickness of the polarizer layer formed by apply|coating and hardening the composition containing a dichroic dye and a polymeric compound is 10 micrometers or less normally, Preferably they are 0.5 micrometer or more and 8 micrometers or less, More preferably, they are 1 micrometer or more and 5 micrometers or less. am.

(platelet)

The present invention can include a plate-like body 105 exemplified in a touch sensor panel or the like as, for example, shown in FIG. 1 as a part of the back plate. As the plate-like body 105, a plate-like body capable of transmitting light other than the touch sensor panel can be used, and the plate-like body (resin plate, resin sheet, resin film, glass plate, glass) exemplified as usable for the front plate 101 . film, etc.) may be used.

The thickness of the plate-like body 105 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 105 may be comprised by only one layer, and may be comprised by two or more layers.

-Touch sensor panel-

As the touch sensor panel, as long as it is a sensor capable of detecting the touched position, the detection method is not limited, and a touch sensor panel such as a resistive film method, a capacitive coupling method, an optical sensor method, an ultrasonic method, an electromagnetic inductive coupling method, or a surface acoustic wave method This is exemplified. Since it is low cost, the touch sensor panel of a resistive film type and a capacitive coupling type is used suitably.

An example of a resistive touch sensor panel includes a pair of substrates disposed opposite to each other, an insulating spacer sandwiched between the pair of substrates, and a transparent conductive film provided as a resistive film on the front surface of the inner side of each substrate; , is constituted by a touch position detection circuit. In an image display device provided with a resistive touch sensor panel, when the surface of the front plate is touched, the opposing resistive films are short-circuited, and a current flows through the resistive film. The touch position detection circuit detects a change in voltage at this time, and the touched position is detected.

An example of the touch sensor panel of the capacitive coupling method is comprised by the board|substrate, the transparent electrode for position detection provided on the whole surface of the board|substrate, and a touch position detection circuit. In an image display device provided with a capacitively coupled touch sensor panel, when the surface of the front plate is touched, the transparent electrode is grounded through the human body's capacitance at the touched point. The touch position detection circuit detects the grounding of the transparent electrode, and the touched position is detected.

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

[phase difference layer]

The laminate 100 may further include one or two or more retardation layers as a part of the rear plate. The retardation layer is usually disposed between the polarizer layer 103 and the plate-shaped body 105 . The retardation layer can be laminated|stacked on the other layer (another retardation layer is included) via the bonding layer 104 comprised from the 1st adhesive layer 102 or the adhesive or adhesive agent mentioned later.

[bonding layer]

The bonding layer 104 is a layer arrange|positioned between the polarizer layer 103 and the plate-shaped object 105, for example. However, the bonding layer 104 is not necessarily limited to this, and it may be arrange|positioned also between the polarizer layer 103 and the retardation layer, between the retardation layer and the plate-shaped object 105, etc. The bonding layer 104 is a layer comprised from an adhesive or an adhesive agent. As the pressure-sensitive adhesive constituting the bonding layer 104, the same formulations as those exemplified for the pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer 102 may be used. (meth)acrylic pressure-sensitive adhesives other than the pressure-sensitive adhesive composition, styrene-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, urethane pressure-sensitive adhesives, polyester pressure-sensitive adhesives, epoxy-based copolymer pressure-sensitive adhesives, and the like may be used.

The bonding layer 104 can illustrate a 2nd adhesive layer as an adhesive layer arrange|positioned between the polarizer layer 103 and the plate-shaped object 105. In this case, the layer formed from the adhesive of the same composition as the adhesive composition which comprises the 1st adhesive layer 102 may be sufficient as a 2nd adhesive layer, and another adhesive layer may be sufficient as it. The second pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer disposed at a position closest to the back plate among the pressure-sensitive adhesive layers constituting the laminate. One layer may be sufficient as a 2nd adhesive layer, or although what consists of two or more layers may be sufficient, Preferably it is one layer. When the second pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive having the same composition as the pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer 102, the storage elastic modulus (G ') at -40°C is the above-described first pressure-sensitive adhesive layer (102) It can be done the same as that shown in the description of.

As an adhesive agent which comprises the bonding layer 104, it can form combining 1 or 2 or more types among a water-based adhesive agent, an active-energy-ray-curable adhesive agent, etc., for example. Examples of the water-based adhesive include a polyvinyl alcohol-based resin aqueous solution, a water-based two-part type urethane-based emulsion adhesive, and the like. The active energy ray-curable adhesive is an adhesive that is cured by irradiating active energy rays such as ultraviolet rays, for example, a polymerizable compound and a photopolymerizable initiator, a photoreactive resin, a binder resin, and a photoreactive crosslinking agent and those containing As said polymerizable compound, photopolymerizable monomers, such as a photocurable epoxy type monomer, a photocurable acrylic type monomer, and a photocurable urethane type monomer, the oligomer derived from these monomers, etc. are mentioned. Examples of the photopolymerization initiator include those 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 104 may be, for example, 1 micrometer or more, Preferably they are 1 micrometer or more and 50 micrometers or less, More preferably, they are 2 micrometers or more and 25 micrometers or less.

The laminated body 200 shown in FIG. 2 is equipped with the front plate 101, the 1st adhesive layer 102, the polarizer layer 103, the bonding layer 104, and the plate-shaped object 105, The bonding layer 108 ), a first retardation layer 106 , a bonding layer 109 , and a second retardation layer 107 .

Examples of the retardation layer (the first retardation layer 106 and the second retardation layer 107) include a positive A plate such as a λ/4 plate and a λ/2 plate, and a positive C plate. The retardation layer may be, for example, a retardation film that can be formed from the above-mentioned thermoplastic resin film, or may be a layer formed by curing a polymerizable liquid crystal compound, that is, a layer containing a cured product of the polymerizable liquid crystal compound, but preferably is the latter.

The thickness of the retardation film may be the same as the thickness of the above-mentioned thermoplastic resin film. The thickness of the retardation layer formed by curing the polymerizable liquid crystal compound 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 formed by hardening|curing a polymeric liquid crystal compound can be formed by apply|coating and hardening a composition containing a polymeric liquid crystal compound to a base film. An orientation layer may be formed between a base film and an application layer. The material and thickness of the base film may be the same as the material and thickness of the above-described thermoplastic resin film. The retardation layer formed by hardening|curing a polymeric liquid crystal compound may be introduce|transduced into the laminated body 100 in the form which has an orientation layer and/or a base film. The base film to which the said composition is apply|coated may be the plate-shaped object 105.

As above-mentioned, an adhesive agent may be used for the bonding layer 108 and the bonding layer 109, and an adhesive may be used, and in this case, an adhesive may just be the agent which consists of the above-mentioned adhesive composition A. As the adhesive, a water-based adhesive or an active energy ray-curable adhesive can be used. Examples of the water-based adhesive include an adhesive composed of a polyvinyl alcohol-based resin aqueous solution, and a water-based two-part type urethane-based emulsion adhesive.

The bonding layer 108, the bonding layer 109, and the bonding layer 104 may be a layer formed from the adhesive or adhesive agent of the same composition, or the layer formed from the adhesive agent or adhesive agent of a different composition may be sufficient as it.

[Method for producing a laminate]

The laminated body 100 can be manufactured by the method including the process of bonding the layers which comprise the laminated body 100 through an adhesive layer or an adhesive bond layer. When bonding layers through an adhesive layer or an adhesive bond layer, in order to improve adhesiveness, it is preferable to perform surface activation processing, such as a corona treatment, with respect to one or both of a bonding surface, for example.

The polarizer layer 103 can be formed directly on the thermoplastic resin film or the base film, and this thermoplastic resin film or the base film may be introduced into the laminate 100 , or peeled from the polarizer layer 103 , It does not need to be a component of a laminated body.

<Display device>

The display device according to the present invention includes the above-described laminate. It is preferable that a display device specifically contains the above-mentioned laminated body and a display element in this order. The type of the display device is not particularly limited, and examples thereof include image display devices such as an organic EL display device, an inorganic EL display device, a liquid crystal display device, and an electroluminescence display device. The display device may have a touch panel function. The laminate is suitable for a display device having flexibility that can be bent or bent.

As the stacking order of the components in the display device, for example, window film (front plate)/circularly polarizing plate/touch sensor panel/organic EL display element, window film/touch sensor panel/circularly polarizing plate/organic EL display element, etc. can be heard It does not have to be limited to the said organic electroluminescent display element as a display element, Conventionally well-known all types of display elements can be used. For example, an inorganic EL display element, a liquid crystal display element, an electroluminescent display element other than organic electroluminescent (electroluminescence) display element are mentioned.

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

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

<Adhesive layer>

The pressure-sensitive adhesive layer according to the present invention is a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition contains a (meth)acrylic polymer, a bifunctional or higher (meth)acrylate monomer having an aliphatic urethane group in a molecule or an oligomer thereof, and a photopolymerization initiator. The pressure-sensitive adhesive layer has a storage elastic modulus (G') at -40°C of 5×10 ³ Pa or more and 1×10 ⁵ Pa or less. Since the adhesive layer which concerns on this invention is excellent in the flexibility at the time of low temperature, and durability in a wet heat environment, it is suitable as a material which forms the adhesive layer of a laminated body.

In the pressure-sensitive adhesive layer, the type of monomer constituting the (meth)acrylic polymer, the weight average molecular weight and content of the (meth)acrylic polymer, the bifunctional or higher (meth)acrylate monomer having an aliphatic urethane group in the molecule, or the type of its oligomer and examples of the content, the weight average molecular weight of the oligomer, the type of the photopolymerization initiator, and the additive that can be blended into the pressure-sensitive adhesive layer are the same as those exemplified in the description of the pressure-sensitive adhesive composition A described above. Moreover, the value of the storage elastic modulus (G') in -40 degreeC of an adhesive layer is also the same as that of the adhesive layer formed from the adhesive composition A mentioned above. For this reason, in the pressure-sensitive adhesive layer according to the present invention, the value of the storage modulus (G') at -40°C is 1×10 ⁴ Pa or more and 1×10 ⁵ Pa or less from the viewpoint of suppressing the occurrence of cracks at low temperatures. desirable.

The adhesive composition which concerns on this invention can be manufactured by a well-known method, for example by collectively mixing each component using a mixer etc.

<Adhesive sheet>

The pressure-sensitive adhesive sheet according to the present invention includes a base material and the pressure-sensitive adhesive layer formed on the base material.

The pressure-sensitive adhesive sheet refers to a thin-film sheet having a thickness of 5 µm or more and 2000 µm or less, preferably 5 µm or more and 1000 µm or less in total of the base material and the pressure-sensitive adhesive layer, and it is preferable that there is flexibility. As said base material, the peeling film etc. which were given a front plate, a back plate, and the release process mentioned later can be illustrated. The pressure-sensitive adhesive layer can be formed from the pressure-sensitive adhesive composition A. The pressure-sensitive adhesive sheet, when the pressure-sensitive adhesive layer is formed from the pressure-sensitive adhesive composition A, can be formed by applying the pressure-sensitive adhesive composition A on the substrate, and a cured product having a desired degree of curing by irradiating an active energy ray to the pressure-sensitive adhesive layer formed on the substrate. can do.

The release film to which the mold release process was given may be sufficient as the said base material. An adhesive sheet is producible by forming an adhesive layer in sheet form on a peeling film, and bonding another peeling film on the adhesive layer.

(Example)

Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited by these examples.

[thickness of layer]

It measured using the contact-type film thickness measuring apparatus ("MS-5C" manufactured by Nikon Corporation). However, about the polarizer layer and the orientation film mentioned later, it measured using the laser microscope ("OLS3000", the Olympus Corporation make).

[Storage modulus at -40°C (G')]

The storage elastic modulus (G') [Pa] in -40 degreeC was measured using the viscoelasticity measuring apparatus ("MCR-301", manufactured by Anton Paar). The same pressure-sensitive adhesive sheet as used in Examples and Comparative Examples to be described later was 30 mm in width x 30 mm in length, peeling off the release film, laminating a plurality of sheets so as to have a thickness of 150 µm, bonding to a glass plate, and bonding to a measuring chip. In this state, the storage modulus (G') [Pa] was measured by the torsional shearing method under the condition of -40°C and a frequency of 1 Hz.

[Low Temperature Flexibility]

About the laminated body, the evaluation test which confirms low-temperature flexibility was done using the bending|flexion evaluation facility (Science Town company make, STS-VRT-500). 3 : is a figure which shows typically the method of this evaluation test. As shown in Fig. 3, the two mounting tables 501 and 502 that are individually movable are arranged so that the gap C is 5.0 mm (2.5R), and the center of the width direction is at the center of the gap C. The stacked body 100 was fixed and arranged so as to be positioned (FIG. 3(a)). At this time, the laminated body 100 was arrange|positioned so that the front plate 101 might become upward. Then, by rotating the two mounting tables 501 and 502 upward 90 degrees with the positions P1 and P2 as the centers of the rotation axes, a bending force is applied to the area of the laminate 100 corresponding to the gap C of the mounting table. was added (Fig. 3(b)). After that, the two mounting tables 501 and 502 were returned to their original positions (FIG. 3 (a)). The above series of operations was completed, and the number of times of addition of the bending force was counted once. After doing this repeatedly at -40 ° C., the presence or absence of occurrence of cracks in the region corresponding to the gap C between the mounting tables 501 and 502 of the laminate 100 is checked, and the evaluation criteria described later ( It evaluated based on rank A-E). The moving speed of the mounting tables 501 and 502 and the additional pace of bending force were made into the same conditions also in the evaluation test with respect to any laminated body. About the laminated body after bending each laminated body, visual observation evaluated the presence or absence of crack, haze, and fracture|rupture generation|occurrence|production, respectively. In rank E, "adhesive omission" means the phenomenon in which an adhesive protrudes to the outside of a laminated body.

A: No cracks occurred even when the number of additions of bending force reached 100,000

B: Cracks occurred when the number of additions of bending force was 50,000 or more and less than 100,000

C: Cracks occurred when the number of additions of the bending force was 20,000 or more and less than 50,000

D: Cracks occurred when the number of additions of bending force was 10,000 or more and less than 20,000

E: Cracks/adhesive detachment occurred when the number of times of added bending force was less than 10,000

[Moisture and heat resistance bending durability]

The laminate 100 was folded and bent (2.5R) in the same manner as in the low-temperature flexibility test. In a bent state, after leaving it to stand for 72 hours in an environment of 60°C/90%RH, the presence or absence of cracks in the pressure-sensitive adhesive layer, and when cracks occur, the dimensions of the cracks are checked, and evaluation criteria (ranks A to E) was evaluated. In rank E, "adhesive omission" means the phenomenon in which an adhesive protrudes to the outside of a laminated body.

A: No cracks

B: crack generation of 1 mm or less

C: occurrence of cracks exceeding 1 mm and less than or equal to 5 mm

D: occurrence of cracks exceeding 5 mm and less than or equal to 10 mm

E: Cracks exceeding 10 mm/Adhesive peeling occurred

[Weight Average Molecular Weight (Mw)]

The weight average molecular weight (Mw) of the (meth)acrylic polymer was calculated|required by the following size exclusion chromatography (SEC) using tetrahydrofuran as a polystyrene conversion number average molecular weight (Mn) in a mobile phase. Specifically, the (meth)acrylic polymer used as the measurement object was dissolved in tetrahydrofuran at a density|concentration of about 0.05 mass %, and 10 microliters was injected into SEC. The mobile phase was flowed at a flow rate of 1.0 mL/min. As the column, PLgel MIXED-B (manufactured by Polymer Laboratories) was used. A UV-VIS detector (trade name: Agilent GPC) was used as the detector.

The weight average molecular weight (Mw) of the (meth)acrylate oligomer more than bifunctional which has an aliphatic urethane group in a molecule|numerator was calculated|required by the method similar to the measuring method of the weight average molecular weight of a (meth)acrylic-type polymer. For example, the weight average molecular weight (Mw) of Miramer PU2560 (Miwon Specialty Chemical Co., Ltd. (Korea)) mentioned later which is an example of the (meth)acrylate oligomer more than bifunctional is 10400.

[(meth)acrylic polymer]

(Production Example A1)

A monomer mixture comprising 95 parts by mass of 2-ethylhexyl acrylate (2-EHA) monomer and 5 parts by mass of butyl acrylate (BA) monomer in a 1 L reactor equipped with a cooling device so that nitrogen gas is refluxed to facilitate temperature control. After the addition, nitrogen gas was refluxed for 1 hour to remove oxygen, and then maintained at 80°C. After uniformly mixing the monomer mixture, 0.05 parts by mass of a photoinitiator benzyldimethyl ketal (I-651) and 0.05 parts by mass of 1-hydroxycyclohexylphenyl ketone (I-184) were added thereto. Then, a UV lamp (10 mW) was irradiated, stirring, and the (meth)acrylate polymer (A1) of 450,000 weight average molecular weights (Mw) was manufactured.

(Production Example A2)

A monomer mixture comprising 80 parts by mass of 2-ethylhexyl acrylate (2-EHA) monomer and 20 parts by mass of butyl acrylate (BA) monomer in a 1 L reactor equipped with a cooling device so that nitrogen gas is refluxed to facilitate temperature control. After the addition, nitrogen gas was refluxed for 1 hour to remove oxygen, and then maintained at 80°C. After uniformly mixing the monomer mixture, 0.05 parts by mass of a photoinitiator benzyldimethyl ketal (I-651) and 0.05 parts by mass of 1-hydroxycyclohexylphenyl ketone (I-184) were added thereto. Then, while stirring, a UV lamp (10 mW) was irradiated to prepare a (meth)acrylate polymer (A2) having a weight average molecular weight (Mw) of 550,000.

(Production Example A3)

To facilitate temperature control by refluxing nitrogen gas, 98 parts by mass of 2-ethylhexyl acrylate (2-EHA) monomer and 2 β-carboxyethyl acrylate (β-CEA) monomer 2 in a 1 L reactor equipped with a cooling device After introducing 150 parts by mass of a monomer mixture composed of parts by mass and ethyl acetate (EAc) as a solvent, nitrogen gas was refluxed for 1 hour to remove oxygen, and then maintained at 80°C. After uniformly mixing the monomer mixture and the solvent, 0.02 parts by mass of a thermal polymerization initiator 2,2-azobisisobutyronitrile (AIBN) was added thereto. Then, the (meth)acrylate polymer (A3) of 800,000 weight average molecular weights (Mw) was manufactured by hold|maintaining at 80 degreeC, stirring.

(Production Example A4)

To facilitate temperature control by refluxing nitrogen gas, a monomer mixture comprising 98 parts by mass of 2-ethylhexyl acrylate (2-EHA) monomer and 2 parts by mass of acrylic acid (AA) monomer and a solvent in a 1 L reactor equipped with a cooling device In order to remove oxygen after putting in 150 mass parts of ethyl acetate (EAc) as a furnace, nitrogen gas was refluxed for 1 hour, and it was maintained at 80 degreeC. After uniformly mixing the monomer mixture and the solvent, 0.02 parts by mass of thermal polymerization initiator 2,2-azobisisobutyronitrile (AIBN) was added thereto. Then, the (meth)acrylate polymer (A4) of 850,000 weight average molecular weights (Mw) was manufactured by hold|maintaining at 80 degreeC, stirring.

Table 1 shows the composition of Production Examples A1 to A4 collectively.

[Table 1]

<Examples 1 to 4 and Comparative Examples 1 to 6>

(1) Preparation of adhesive sheet

It was mixed with the component and ratio shown in Table 2, the adhesive composition of Examples 1-4 and Comparative Examples 1-6 was manufactured, and the adhesive sheet was produced by the method mentioned later using this. In Table 2, "(meth)acrylate polymer", "aliphatic urethane (meth)acrylic monomer or its oligomer, or other components" representing a bifunctional or higher (meth)acrylate monomer or oligomer having an aliphatic urethane group in the molecule ', "photoinitiator", and "crosslinking agent" about the compounding quantity of each, the quantity converted into solid content is shown.

[Table 2]

That is, the pressure-sensitive adhesive compositions of Examples 1 to 4 and Comparative Examples 1 to 6 were applied to a thickness of 25 µm on a release film B (polyethylene terephthalate film, 38 µm in thickness) coated with a silicone release agent, respectively. The adhesive sheet which consists of peeling film A / adhesive layer / peeling film B was produced by bonding the peeling film A (polyethylene terephthalate film, 38 micrometers in thickness) on it, and also performing UV irradiation. About this adhesive sheet (The adhesive sheet of Examples 1-4 and Comparative Examples 1-6), while measuring the storage elastic modulus (G') in -40 degreeC, respectively, it evaluated based on the above-mentioned evaluation criteria. .

A result is shown in Table 3.

(2) Production of a laminate

Moreover, the laminated body which consists of the laminated structure demonstrated next using the adhesive sheet of Examples 1-4 and Comparative Examples 1-6 was comprised.

[Front panel]

As a front plate, a polyimide film (length 177 mm x width 105 mm, overall thickness: 70 µm, each hard coat layer thickness: 10 µm, polyimide film thickness: 50 µm) having hard coating layers on both sides was prepared as the front plate. . Hereinafter, the said polyimide film is also described as a "window film."

[Polarizer layer]

(Polymerizable liquid crystal compound)

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

[Tue 1]

[Tue 2]

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

The azo dye described in the Example of Unexamined-Japanese-Patent No. 2013-101328 represented by following formula (2-1a), (2-1b), (2-3a) was used for a dichroic dye.

[Tue 3]

[Tuesday 4]

[Tue 5]

(Composition for forming a polarizer layer)

The composition for polarizer layer formation is represented by 75 parts of compound (1-6), 25 parts of compound (1-7), said formula (2-1a) as said dichroic dye, (2-1b), (2-3a) 2.5 parts each of an azo dye, 6 parts by weight of 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure369, manufactured by BASF Japan) as a polymerization initiator, and polyacrylic as a leveling agent 1.2 parts of a rate compound (BYK-361N, BYK-Chemie company make) was mixed with 400 parts of toluene of a solvent, and it prepared by stirring the obtained mixture at 80 degreeC for 1 hour.

(Polymer 1)

Polymer 1 is a polymer which has a photoreactive group which consists of the following structural units.

[Tue 6]

From the GPC measurement, the molecular weight of the obtained polymer 1 showed a number average molecular weight of 28200 and Mw/Mn1.82, and the monomer content was 0.5%.

(Composition for forming an alignment layer)

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

(Manufacture of circular polarizer)

On a base material (triacetyl cellulose film, thickness 25 µm), the composition for forming an alignment film was applied by a bar coating method, and dried by heating in a drying oven at 80°C for 1 minute to obtain a dry coating film. The polarization UV irradiation process was performed to this dry coating film, and the 1st alignment film AL1 was formed. Polarized UV treatment transmits light irradiated from a UV irradiation device ("SPOT CURE SP-7", manufactured by Ushio Denki Co., Ltd.) through a wire grid ("UIS-27132##", manufactured by Ushio Denki Co., Ltd.) and the amount of accumulated light measured at a wavelength of 365 nm was 100 mJ/cm 2 . The thickness of the first alignment layer AL1 was 100 nm.

On the first alignment layer AL1, the composition for forming a polarizer layer was applied by a bar coating method, dried by heating in a drying oven at 120° C. for 1 minute, and then cooled to room temperature. The polarizer layer pol was formed by irradiating an ultraviolet-ray to the dry coating film with the accumulated light amount of 1200 mJ/cm<2> (365 nm standard) using the said UV irradiation apparatus. The thickness of the obtained polarizer layer was 2 micrometers.

On the said polarizer layer, the composition containing polyvinyl alcohol and water was coated so that the thickness after drying might be set to 1 micrometer, and the overcoat layer was formed by drying at 80 degreeC for 3 minutes. On this overcoat layer, a retardation film (11 µm in thickness, layer structure: λ/4 plate (3 µm in thickness))/adhesive layer consisting of a layer in which a polymerizable liquid crystal compound is cured and an alignment film through an acrylic pressure-sensitive adhesive layer having a thickness of 5 µm (Acrylic adhesive layer, thickness 5 micrometers)/Positive C plate (3 micrometers thickness) which consists of the layer and orientation film which the liquid crystal compound hardened|cured) was pasted together.

In this way, a circularly polarizing plate having a thickness of 44 µm and a length of 177 mm × width of 105 mm consisting of a layer structure of TAC film/first alignment film (AL1)/polarizer layer/overcoat layer/adhesive layer/retardation film is obtained, and this is a back plate prepared as

A laminate was manufactured in the following procedure.

That is, as a 1st adhesive layer which comprises a laminated body, the said adhesive sheet (The adhesive sheet of Examples 1-4 and Comparative Examples 1-6) which consists of the above-mentioned peeling film A / adhesive layer / peeling film B was prepared. After peeling off one peeling film A of this adhesive sheet, the exposed adhesive layer was corona-treated.

Corona-treated on the surface by the side of the TAC film in a back board. The exposed adhesive layer and the surface by the side of the TAC film in a back board were bonded together so that the surface which performed corona treatment might become a bonding surface.

Then, peeling film B was peeled off from the said adhesive sheet, and corona-treated to the exposed 1st adhesive layer. One side of the window film was corona-treated. The 1st adhesive layer and the window film were bonded together so that the surface which performed corona treatment might become a bonding surface.

All corona treatment was performed on condition of the following.

Frequency: 20 kHz/Voltage: 8.6 kV/Power: 2.5 kW/Speed: 6 m/min

In this way, the laminated body which consists of a laminated structure of a window film/1st adhesive layer/rear plate (circularly polarizing plate) was produced.

About the said laminated body (the laminated body of Examples 1-4 and Comparative Examples 1-6), while measuring low-temperature flexibility and moist-and-heat resistance bending durability, respectively, it evaluated based on the above-mentioned evaluation criteria.

A result is shown in Table 3.

[Table 3]

According to Table 3, it is understood that the adhesive sheet and laminated body of Examples 1-4 are excellent in the flexibility at the time of a low temperature, and durability in a moist heat environment.

100, 200: laminate
101: front panel
102: first pressure-sensitive adhesive layer
103: polarizer layer
104, 108, 109: bonding layer
105: back plate
106: first retardation layer
107: second retardation layer
501, 502: Stage

Claims (5)

A laminate comprising a front plate, an adhesive layer and a back plate in this order,
The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer, a (meth)acrylate monomer or oligomer thereof having a difunctional or higher having an aliphatic urethane group in the molecule, and a photopolymerization initiator,
The said adhesive layer is a laminated body whose storage elastic modulus (G') at -40 ^{degreeC is 5x10 3} Pa or more and 1x10 ⁵ Pa or less. According to claim 1,
The back plate, the laminate comprising at least one selected from the group consisting of a polarizer layer and a touch sensor panel. A display device comprising the laminate according to claim 1 or 2 . A pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition,
The pressure-sensitive adhesive composition contains a (meth)acrylic polymer, a (meth)acrylate monomer or oligomer thereof having a difunctional or higher function having an aliphatic urethane group in the molecule, and a photopolymerization initiator,
The pressure-sensitive adhesive layer has a storage elastic modulus (G') at -40°C of 5×10 ³ Pa or more and 1×10 ⁵ Pa or less, the pressure-sensitive adhesive layer. A pressure-sensitive adhesive sheet comprising a substrate and the pressure-sensitive adhesive layer according to claim 4 formed on the substrate.

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