KR20210114862A - Optical laminate and display device - Google Patents

Abstract

Provided is an optical laminate which suppresses generation of cracks in an adhesive layer when bent, and a display device comprising the same. The optical laminate comprises a front plate, a first adhesive layer, a polarizing plate, a second adhesive layer, and a back plate arranged in the described order, and the first and second adhesive layers satisfy the following expressions (1), (2): 100<=G_L1'<=1000 (1), 100<=G_L2'<=1000 (2), where G_L1' and G_L2' respectively represent slopes from the origins to maximum stress values on respective stress [Pa]-strain [%] curves at -40℃.

Description

Optical laminate and display device {OPTICAL LAMINATE AND DISPLAY DEVICE}

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

Japanese Patent Application Laid-Open No. 2018-027995 (Patent Document 1) describes a flexible image display device provided with an adhesive layer excellent in stress relaxation characteristics.

Patent Document 1: Japanese Patent Laid-Open No. 2018-027995

When the optical laminated body in which the several layer was laminated|stacked via an adhesive layer was bent, it was easy to generate|occur|produce a crack in an adhesive layer, and there existed a problem that a crack was easy to generate|occur|produce especially in a low-temperature environment.

An object of this invention is to provide the optical laminated body by which generation|occurrence|production of the crack was suppressed in the adhesive layer when it bent, and the display apparatus containing the said optical laminated body.

This invention provides the optical laminated body and display apparatus illustrated below.

[1] A front plate, a first pressure-sensitive adhesive layer, a polarizing plate, a second pressure-sensitive adhesive layer, and a rear plate are provided in this order,

When the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer have a slope from the origin to the maximum stress value in the stress [Pa]-strain [%] curve at a temperature of -40 ° C. to G _L1 ' and G _L2 ', respectively, The optical laminated body which satisfy|fills following formula (1) and Formula (2).

100≤G _L1 '≤1000 (1)

100≤G _L2 '≤1000 (2)

[2] The optical laminate as described in [1] which satisfy|fills following formula (1') and Formula (2').

300≤G _L1 '≤600 (1')

300≤G _L2 '≤600 (2')

[3] The optical laminate according to [1] or [2], wherein the back plate is a touch sensor panel.

[4] A display device comprising the optical laminate according to any one of [1] to [3].

[5] The display device according to [4], wherein the front plate side can be bent inside.

According to the present invention, there is provided an optical laminate in which cracks are suppressed in the pressure-sensitive adhesive layer when bent, and a display device including the optical laminate.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows an example of the optical laminated body which concerns on this invention.
2 is a schematic diagram illustrating a method of measuring a stress-strain value by a tensile test.
3 is a schematic diagram illustrating a bending test.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of the optical laminated body which concerns on this invention is described, referring drawings, this invention is not limited to the following embodiment. In all the drawings below, in order to make each component easy to understand, the scale is adjusted and shown, and the scale of each component shown in a figure and the scale of the actual component do not necessarily correspond.

<Optical laminated body>

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing of the optical laminated body by one Embodiment of this invention. The optical laminate 100 shown in FIG. 1 is equipped with the front plate 101, the 1st adhesive layer 102, the polarizing plate 103, the 2nd adhesive layer 104, and the back plate 105 in this order. do. Hereinafter, the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104 may be collectively referred to as an adhesive layer.

Although the thickness of the optical laminated body 100 is not specifically limited since it differs with the function calculated|required of an optical laminated body, the use of an optical laminated body, etc., For example, it is 30 micrometers or more and 1500 micrometers or less, Preferably it is 40 micrometers or more 1000. It is micrometer or less, More preferably, they are 50 micrometers or more and 500 micrometers or less.

The planar shape of the optical laminate 100 may be, for example, a square shape, Preferably it is a rectangular shape which has a long side and a short side, More preferably, it is a rectangle. When the shape of the surface direction of the optical 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 the optical laminated body 100, the corner part may be R-processed, the edge part may be notched, or the punching process may be carried out.

The optical laminate 100 can be used, for example, in a display device or the like. A display apparatus is not specifically limited, For example, an organic electroluminescent (organic EL) display apparatus, an inorganic electroluminescent (inorganic EL) display apparatus, a liquid crystal display apparatus, an electroluminescent display apparatus, etc. are mentioned. The optical laminate 100 is suitable for a bendable display device.

_{[Slope G L} ' from the origin to the maximum stress value in the stress-strain curve]

The slope from the origin to the maximum stress value in the stress [Pa]-strain curve [%] at the temperature of -40 ° C. of the first pressure-sensitive adhesive layer 102 and the second pressure-sensitive adhesive layer 104 is G _L1 ' and G _L2 ', respectively. In one case, the optical laminated body 100 satisfy|fills following formula (1) and Formula (2).

100≤G _L1 '≤1000 (1)

100≤G _L2 '≤1000 (2)

When the pressure-sensitive adhesive layer is subjected to a tensile test, a stress-strain curve can be drawn with stress as the ordinate and strain as the abscissa. In general, as the strain increases, the stress generated in the pressure-sensitive adhesive layer also increases, and the stress becomes maximum just before cohesive failure occurs in the pressure-sensitive adhesive layer. In the stress-strain curve of the pressure-sensitive adhesive layer, the slope G _L ′ from the origin to the maximum stress value is represented by (maximum stress value)/(strain amount when stress becomes maximum). G _L ' reflects not only the stress change when the pressure-sensitive adhesive layer is elastically deformed but also the stress change when the pressure-sensitive adhesive layer is plastically deformed. When G _L ' is large, the stress generated with respect to the deformation|transformation of an adhesive layer is large, and an adhesive layer is excellent in cohesive force. When G _L ' is small, the stress which arises with respect to the deformation|transformation of an adhesive layer is small, and an adhesive layer is easy to deform|transform and it is thought that it is hard to be destroyed. G _L ' can be calculated|required according to the method described in the column of the Example mentioned later.

Even if it bends the optical laminated body 100 which satisfy|fills Formula (1) and Formula (2), it is hard to generate|occur|produce a crack in an adhesive layer. Even if it bends especially in a low-temperature environment, generation|occurrence|production of a crack in an adhesive layer can be suppressed. The optical laminate 100 satisfying the formulas (1) and (2) is, for example, bent 20,000 times or more so that the bending radius becomes 2.5 mm at a temperature of -20°C according to the description in the column of Examples to be described later. The durability of the pressure-sensitive adhesive layer can be improved to the extent that no sea-island cracks are generated. Generation|occurrence|production of the crack of an adhesive layer can be judged by observation under an optical microscope.

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

The optical laminate 100 preferably satisfies the following formulas (1') and (2').

300≤G _L1 '≤600 (1')

300≤G _L2 '≤600 (2')

Even if it bends the optical laminated body 100 which satisfy|fills Formula (1') and (2') in a low-temperature environment, generation|occurrence|production of a crack in an adhesive layer can be suppressed more.

In addition, when bending the front plate inside, it is preferable that the optical laminated body 100 satisfy|fills following formula (3) or (3').

G _L1 '≤G _L2 ' (3)

G _L1 '<G _L2 '(3')

When bending the front plate outward, it is preferable that the optical laminated body 100 satisfy|fills following formula (4) or (4').

G _L1 '≥G _L2 ' (4)

G _L1 '>G _L2 '(4')

When the optical laminated body 100 is bent, large stress arises by the adhesive layer used as an inner-diameter side. Therefore, G _L 'that can be more compact, than inhibiting the occurrence of cracks in the adhesive layer of the optical stack 100 by arranging such that the inner side in the case where the bending stress relaxation excellent pressure-sensitive adhesive layer.

G _L 'is a desired numerical range by adjusting the type and compounding amount of the monomer constituting the base polymer included in the pressure-sensitive adhesive composition used for the pressure-sensitive adhesive layer, the type and compounding amount of the polymerizable compound, the type and irradiation amount of active energy rays, etc. can do. For example, when the base polymer contained in the pressure-sensitive adhesive composition contains many structural units derived from a long-chain alkyl (meth)acrylic monomer having 10 or more carbon atoms, G _L ′ tends to become small. When the pressure-sensitive adhesive composition contains a large amount of a long-chain alkyl (meth)acrylic monomer having 10 or more carbon atoms as a polymerizable compound, G _L ′ tends to become small. For example, when an adhesive composition contains many compounds which have a cyclic structure like a cyclohexyl group as a polymeric compound, there exists a tendency for _{G L' to become large.}

[Front panel]

The material and thickness of the front plate 101 are not limited as long as it is a plate-shaped body which can transmit light. The front plate 101 may be comprised by only one layer, and may be comprised by two or more layers. As the front plate 101, 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.), a resin plate-shaped object, and glass and laminates of plate-shaped bodies. The front plate 101 may constitute the outermost surface of the display device.

The thickness of the front plate 101 may be, for example, 10 µm or more and 300 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 the present invention, the thickness of each layer constituting the optical laminate 100 can be measured according to the thickness measurement method described in Examples to be described later.

Examples of the resin constituting the resin plate-shaped body 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 and polymers such as polyether ether ketone, polyether sulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, and polyamideimide. These polymers can be used individually or in mixture of 2 or more types. From the viewpoint of improving strength and transparency, the resin-made plate is preferably a resin film formed of a polymer such as polyimide, polyamide, or polyamideimide.

From the viewpoint of hardness, the front plate 101 may be a resin film provided with a hard coat layer. The hard-coat layer may be formed in one surface of a resin film, and may be formed in both surfaces. By providing a hard-coat layer, hardness and scratch resistance can be improved. The hard coat layer is, for example, a cured layer of an ultraviolet curable resin. Examples of the ultraviolet curable resin include an acrylic resin, a silicone resin, a polyester resin, a urethane resin, an amide resin, and an epoxy resin. The hard-coat layer may contain the additive in order to improve hardness. The additive is not particularly limited, and examples thereof include inorganic fine particles, organic fine particles, and mixtures thereof. When it has a hard-coat layer on both surfaces of a resin film, the composition and thickness of each hard-coat layer may mutually be mutually same, and may differ from each other.

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 1000 micrometers or less, for example, and 10 micrometers or more and 100 micrometers or less may be sufficient as them. By using a glass plate, the front plate 101 which has excellent mechanical strength and surface hardness can be comprised.

When the optical 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 What has a cut function, a viewing angle adjustment function, etc. may be sufficient.

[First Adhesive Layer]

The 1st adhesive layer 102 is interposed between the front plate 101 and the polarizing plate 103, and these are bonded together. Although the 1st adhesive layer 102 may consist of one layer and may consist of two or more layers, Preferably it consists of one layer.

The first pressure-sensitive adhesive layer 102 may be composed of a pressure-sensitive adhesive composition containing (meth)acrylic resin, rubber-based resin, urethane-based resin, ester-based resin, silicone-based resin, and polyvinyl ether-based resin as a main component (base polymer). As the pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer 102 , a pressure-sensitive adhesive composition containing, as a base polymer, a (meth)acrylic resin excellent in transparency, weather resistance, heat resistance, and the like is suitable.

As the (meth)acrylic resin used in the pressure-sensitive adhesive composition, (meth)acrylic acid ester, such as (meth)butyl acrylate, (meth)ethyl acrylate, (meth)acrylate isooctyl, (meth)acrylic acid 2-ethylhexyl, etc. Or the polymer or copolymer which uses 2 or more types as a monomer is used suitably. It is preferable to copolymerize a polar monomer with a base polymer. As the polar monomer, (meth)acrylic acid compound, (meth)acrylic acid 2-hydroxypropyl compound, (meth)acrylic acid hydroxyethyl compound, (meth)acrylamide compound, N,N-dimethyl aminoethyl (meth)acrylate Monomers, such as a compound and a glycidyl (meth)acrylate compound, which have a carboxyl group, a hydroxyl group, an amido group, an amino group, an epoxy group, etc. are mentioned.

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, has adhesiveness even before active energy ray irradiation, and can be adhered to an adherend such as a film, and can be irradiated with active energy rays It has the property of being able to adjust the adhesion by hardening by It is preferable that an active energy ray hardening-type adhesive composition is an ultraviolet curable type. The active energy ray-curable adhesive composition further contains an active energy ray-polymerizable compound other than a base polymer and a crosslinking agent. You may contain a photoinitiator, a photosensitizer, etc. as needed.

As an active-energy-ray-polymerizable compound, For example, the (meth)acrylate monomer which has at least 1 piece(s) of (meth)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 may contain 0.1 parts by mass or more, 1 part by mass or more, or 5 parts by mass or more, and 20 parts by mass or less, or 15 parts by mass or less of the active energy ray polymerizable compound with respect to 100 parts by mass of the base polymer. can

As a photoinitiator, benzophenone, benzyl dimethyl ketal, 1-hydroxy cyclohexylphenyl ketone etc. are mentioned, for example. A photoinitiator may contain 1 type or 2 or more types. When an adhesive composition contains a photoinitiator, 0.01 mass part or more and 3.0 mass parts or less may be sufficient as the total content with respect to 100 mass parts of solid content of an adhesive composition, for example.

The pressure-sensitive adhesive composition 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, corrosion inhibitors, and crosslinking agents.

The first pressure-sensitive adhesive layer 102 may be formed by applying the organic solvent dilution solution of the pressure-sensitive adhesive composition on a substrate and drying the mixture. The first pressure-sensitive adhesive layer 102 may be formed using a pressure-sensitive adhesive sheet formed using the pressure-sensitive adhesive composition. When an active energy ray hardening-type adhesive composition is used, it can be set as the adhesive layer which has a desired degree of hardening by irradiating an active energy ray to the formed adhesive layer.

Although the thickness of the 1st adhesive layer 102 is not specifically limited, For example, it is preferable that they are 1 micrometer or more and 100 micrometers or less, It is more preferable that they are 3 micrometers or more and 50 micrometers or less, 20 micrometers or more may be sufficient.

[Polarizer]

The polarizing plate 103 may be, for example, a linear polarizing plate, a circularly polarizing plate, or an elliptically polarizing plate. Hereinafter, a circularly polarizing plate and an elliptically polarizing plate may be generically called and simply called a circularly polarizing plate. The circularly polarizing plate includes a linearly polarizing plate and a retardation layer. Since the circularly polarizing plate can absorb the external light reflected in an image display apparatus, it can give the optical laminated body 100 a function as an antireflection film.

The thickness of the polarizing plate 103 may be 5 micrometers or more normally, 20 micrometers or more may be sufficient as it, 25 micrometers or more may be sufficient, and 30 micrometers or more may be sufficient as it. Moreover, it is preferable that it is 80 micrometers or less, and, as for the thickness of the polarizing plate 103, it is more preferable that it is 60 micrometers or less.

(linear polarizer)

The linearly polarizing plate has a function of selectively transmitting linearly polarized light in any one direction from non-polarized light rays such as natural light. A linear polarizing plate contains a stretched film or stretched layer to which a dichroic dye is adsorbed, a cured product of a polymerizable liquid crystal compound, and a dichroic dye, and the dichroic dye is dispersed in the cured product of the polymerizable liquid crystal compound and is oriented A layer etc. can be provided as a polarizer layer. When the dye is dispersed and oriented in an anisotropic solute, it may appear colored in a certain direction and appear almost colorless in a direction perpendicular to this. A pigment showing this phenomenon is called a dichroic pigment.

The linear polarizing plate using the liquid crystal layer as a polarizer layer is preferable because there is no restriction|limiting in a bending direction compared with the stretched film or stretched layer which made the dichroic dye adsorb|suck.

(1) A polarizer layer which is a stretched film or a stretched layer to which a dichroic dye is adsorbed

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, and dyeing a polyvinyl alcohol-based resin film with a dichroic dye such as iodine, thereby converting the dichroic dye to It can manufacture through the process of making it adsorb|suck, the process of treating the polyvinyl alcohol-type resin film to which the dichroic dye has adsorbed with boric acid aqueous solution, and the process of washing with water after the process with boric acid aqueous solution.

The thickness of a polarizer layer is 30 micrometers or less normally, Preferably it is 18 micrometers or less, More preferably, it is 15 micrometers or less. Making the thickness of the polarizer layer thin is advantageous for thinning the polarizing plate 103 . The thickness of a polarizer layer may be 1 micrometer or more normally, for example, 5 micrometers or more may be sufficient.

Polyvinyl alcohol-type resin is obtained by saponifying polyvinyl acetate-type resin. As polyvinyl acetate-type resin, the copolymer of vinyl acetate and other monomer copolymerizable to this other than polyvinyl acetate which is a homopolymer of vinyl acetate is used. Examples of the other monomer copolymerizable with vinyl acetate include an unsaturated carboxylic acid compound, an olefin compound, a vinyl ether compound, an unsaturated sulfone compound, and a (meth)acrylamide compound 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-type resin may be modified|denatured, and polyvinyl formal, polyvinyl acetal, etc. which were modified|denatured with aldehydes can also 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 step of applying a coating liquid containing the polyvinyl alcohol-based resin on a base film, a step of uniaxially stretching the obtained laminated film, a uniaxially stretching lamination By dyeing the polyvinyl alcohol-based resin layer of the film with a dichroic dye, the dichroic dye is adsorbed to form a polarizer layer; It can be manufactured through the process of washing with water later. You may use the base film used in order to form a polarizer layer as a protective layer of a polarizer layer. You may peel and remove a 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 thermoplastic resin film mentioned later.

The polarizer layer which is the stretched film or stretched layer to which the dichroic dye was adsorbed may be used as a linear polarizing plate as it is, and may form a protective layer on the one side or both surfaces, and may use it as a linear polarizing plate. As a protective layer, the thermoplastic resin film mentioned later can be used. A polarizer layer and a protective layer can be laminated|stacked through the bonding layer mentioned later. The thickness of the linear polarizing plate obtained becomes like this. Preferably they are 2 micrometers or more and 40 micrometers or less.

The thermoplastic resin film is, for example, a cyclopolyolefin-based resin film; Cellulose acetate-type resin film which consists of resin, such as a triacetyl cellulose and a diacetyl cellulose; polyester-based resin films made of resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate-based resin film; (meth)acrylic resin film; Well-known films in the art, such as a polypropylene resin film, are mentioned.

The thickness of a thermoplastic resin film is 100 micrometers or less normally from a viewpoint of improving a flexibility, Preferably it is 80 micrometers or less, More preferably, it is 60 micrometers or less, More preferably, it is 40 micrometers or less, Even more preferably, it is 30 micrometers. It is micrometer or less, and is 5 micrometers or more normally, Preferably it is 10 micrometers or more.

The hard-coat layer may be formed on the thermoplastic resin film. The hard-coat layer may be formed in one surface of a thermoplastic resin film, and may be formed in both surfaces. By providing a hard-coat layer, it can be set as the thermoplastic resin film which improved hardness and scratch resistance. A hard-coat layer can be formed by the method similar to the hard-coat layer formed in the above-mentioned resin film.

(2) a polarizer layer that is a liquid crystal layer

The polymerizable liquid crystal compound used to form the liquid crystal layer is a compound having a polymerizable reactive group and exhibiting liquid crystallinity. A polymerizable reactive group is a group which participates in a polymerization reaction, and it is preferable that it is a photopolymerizable reactive group. The photopolymerization reactive group refers to a group capable of participating in a polymerization reaction by an active radical, an acid, or the like generated from a photopolymerization initiator. Examples of the photopolymerizable functional group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. have. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferable, and an acryloyloxy group is more preferable. The kind of the polymerizable liquid crystal compound is not particularly limited, and a rod-shaped liquid crystal compound, a disk-shaped liquid crystal compound, and a mixture thereof can be used. The liquid crystallinity of the polymerizable liquid crystal compound may be a thermotropic liquid crystal or a lyotropic liquid crystal, and a nematic liquid crystal or a smectic liquid crystal may be sufficient as a normal-order structure.

As a dichroic dye used for the polarizer layer which is a liquid crystal layer, it is preferable to have an absorption maximum wavelength (λMAX) in the range of 300-700 nm. As such a dichroic dye, although an acridine dye, an oxazine dye, a cyanine dye, a naphthalene dye, an azo dye, an anthraquinone dye, etc. are mentioned, for example, Among these, an azo dye is preferable. As an azo dye, a monoazo dye, a bisazo dye, a trisazo dye, a tetrakis azo dye, a stilbenazo dye, etc. are mentioned, Preferably they are a bisazo dye and a trisazo dye. Although a dichroic dye may be individual or may combine 2 or more types, it is preferable to combine 3 or more types. In particular, it is more preferable to combine three or more types of azo compounds. A part of the dichroic dye may have a reactive group, and may have liquid crystallinity.

The polarizer layer, which is a liquid crystal layer, is formed by, for example, applying a composition for forming a polarizer layer comprising a polymerizable liquid crystal compound and a dichroic dye on an alignment film formed on a base film, and polymerizing and curing the polymerizable liquid crystal compound. can do. On a base film, you may form a polarizer layer by apply|coating the composition for polarizer layer formation, forming a coating film, and extending|stretching this coating film with a base film. You may use the base film used in order to form a polarizer layer as a protective layer of a polarizer 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.

A composition for forming a polarizer layer containing a polymerizable liquid crystal compound and a dichroic dye, and a method for producing a polarizer layer using the composition include Japanese Patent Laid-Open Nos. 2013-37353, 2013-33249, and Japanese Patents. What was described in Unexamined-Japanese-Patent No. 2017-83843 etc. can be illustrated. The composition for polarizer layer formation may further contain additives, such as a solvent, a polymerization initiator, a crosslinking agent, a leveling agent, antioxidant, a plasticizer, and a sensitizer other than a polymeric liquid crystal compound and a dichroic dye. These components may use only 1 type, respectively, and may use them in combination of 2 or more type.

The polymerization initiator which may be contained in the composition for forming a polarizer layer is a compound capable of initiating a polymerization reaction of a polymerizable liquid crystal compound, and a photopolymerization initiator is preferable from the viewpoint of being able to initiate a polymerization reaction under lower temperature conditions. . Specifically, a photoinitiator capable of generating active radicals or acids by the action of light is exemplified, and among them, a photoinitiator capable of generating radicals by the action of light is preferable. To [ content of a polymerization initiator / 100 weight part of total amounts of a polymeric liquid crystal compound ], Preferably they are 1 mass part or more and 10 mass parts or less, More preferably, they are 3 mass parts or more and 8 mass parts or less. If it exists in this range, reaction of a polymeric group will fully advance and it will be easy to stabilize the orientation state of a liquid crystal compound.

The thickness of the polarizer layer which is a liquid crystal layer 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.

The polarizer layer which is a liquid crystal layer may use as a linear polarizing plate, without peeling and removing a base film, It is good also as a linear polarizing plate by peeling and removing a base film from a polarizer layer. The polarizer layer, which is a liquid crystal layer, may or may not have an alignment film. The polarizer layer, which is a liquid crystal layer, may be used as a linear polarizing plate by forming a protective layer on one or both surfaces thereof. As a protective layer, the above-mentioned thermoplastic resin film can be used.

The polarizer layer which is a liquid crystal layer may have an overcoat layer on one side or both surfaces of a polarizer layer for the purpose of protection of a polarizer layer, etc. An overcoat layer can be formed by apply|coating the material (composition) for forming an overcoat layer on a polarizer layer, for example. As a material which comprises an overcoat layer, a photocurable resin, a water-soluble polymer, etc. are mentioned, for example. As a material constituting the overcoat layer, (meth)acrylic resin, polyvinyl alcohol-based resin, or the like can be used.

(retardation layer)

The number of retardation layers may be one, and two or more layers may be sufficient as them. The retardation layer may have the overcoat layer which protects the surface, the base film etc. which support the retardation layer. The retardation layer may include a λ/4 layer and further include at least one of a λ/2 layer or a positive C layer. When the retardation layer contains the λ/2 layer, the λ/2 layer and the λ/4 layer are sequentially laminated from the linear polarizing plate side. When the retardation layer includes the positive C layer, the λ/4 layer and the positive C layer may be sequentially laminated from the linear polarizing plate side, or the positive C layer and the λ/4 layer may be laminated sequentially from the linear polarizing plate 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 from the resin film exemplified as the material for the protective layer, or may be formed from a layer in which a polymerizable liquid crystal compound is cured. The retardation layer may further include an alignment film. The retardation layer may have a bonding layer for bonding the λ/4 layer, the λ/2 layer, and the positive C layer.

When curing a polymerizable liquid crystal compound to form a retardation layer, a retardation layer can be formed by apply|coating and hardening a composition containing a polymeric liquid crystal compound to a base film. You may form an orientation film 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 thermoplastic resin film. When forming a retardation layer from the layer formed by hardening|curing a polymeric liquid crystal compound, the retardation layer may be contained in the optical laminated body in the form which has an orientation film and a base film. A phase difference layer can be bonded together via the bonding layer mentioned later on the surface on the opposite side to the visual recognition side of a linear polarizing plate.

[Second adhesive layer]

The 2nd adhesive layer 104 is interposed between the polarizing plate 103 and the back plate 105, and these are bonded together. One layer may be sufficient as the 2nd adhesive layer 104, Although what consists of two or more layers may be sufficient, Preferably it is one layer.

Composition and blending components of the pressure-sensitive adhesive composition constituting the second pressure-sensitive adhesive layer 104, the type of the pressure-sensitive adhesive composition (whether active energy ray-curable or thermosetting type, etc.), additives that can be blended into the pressure-sensitive adhesive composition, production of the second pressure-sensitive adhesive layer The method, the thickness of the second pressure-sensitive adhesive layer, and the like are the same as those shown in the description of the first pressure-sensitive adhesive layer 102 described above.

The second pressure-sensitive adhesive layer 104 may be the same as or different from the first pressure-sensitive adhesive layer 102 in the composition, blending component, thickness, and the like of the pressure-sensitive adhesive composition.

[bonding layer]

The optical laminated body 100 can contain the bonding layer for bonding two layers together. A bonding layer is a layer comprised from an adhesive or an adhesive agent. The adhesive composition similar to the adhesive composition which comprises the 1st adhesive layer 102 mentioned above can be used for the adhesive used as the material of a bonding layer. The bonding layer is different from the other adhesive, for example, the adhesive constituting the first adhesive layer 102, a (meth)acrylic adhesive, a styrene adhesive, a silicone adhesive, a rubber adhesive, a urethane adhesive, a polyester adhesive, an epoxy adhesive. A copolymer adhesive or the like can also be used.

As an adhesive agent used as the material of a bonding layer, it can form combining 1 type, or 2 or more types among a water-system adhesive agent, an active energy ray hardening-type adhesive agent, etc., for example. Examples of the water-based adhesive include a polyvinyl alcohol-based resin aqueous solution and a water-based two-component urethane-based emulsion adhesive. An active energy ray-curable adhesive is an adhesive that is cured by irradiating active energy rays such as ultraviolet rays, for example, an adhesive containing a polymerizable compound and a photopolymerization initiator, an adhesive containing a photoreactive resin, a binder resin, and a photoreactive crosslinking agent and adhesives containing As said polymeric compound, photopolymerizable monomers, such as a photocurable epoxy type monomer, a photocurable acrylic type monomer, and a photocurable urethane type monomer, and the oligomer derived from these monomers, etc. are mentioned. As said photoinitiator, the compound containing the substance which irradiates active energy rays, such as an ultraviolet-ray, and generate|occur|produces active species, such as a neutral radical, an anion radical, and a cationic radical, is mentioned.

The thickness of the bonding layer may be, for example, 1 µm or more, preferably 1 µm or more and 25 µm or less, more preferably 2 µm or more and 15 µm or less, and still more preferably 2.5 µm or more and 5 µm or less.

The two opposing surfaces bonded together through a bonding layer may perform corona treatment, a plasma treatment, a flame treatment, etc. beforehand, and may have a primer layer etc.

[Backboard]

As the back plate 105, a plate-like body capable of transmitting light, a component used in a normal display device, or the like can be used.

The thickness of the back plate 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.

As a plate-shaped object used for the back plate 105, it may be comprised with only one layer, and may be comprised with two or more layers. As the back plate 105, the plate-shaped body illustrated in the front plate 101 can be used.

As a component used for a normal display apparatus, a touch sensor panel, organic electroluminescent display element, etc. are mentioned, for example. The back plate 105 is preferably a touch sensor panel. Examples of the stacking order of the components in the display device include front plate/circular polarizing plate/touch sensor panel/organic EL display element, front plate/touch sensor panel/circular polarizing plate/organic EL display element, and the like.

(touch sensor panel)

The touch sensor panel is not limited as long as it is a panel having a sensor (ie, a touch sensor) capable of detecting a touched position. The detection method of the touch sensor 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, and a surface acoustic wave method is exemplified. Since it is low cost, the touch sensor panel of a resistive film type and a capacitive coupling type is used suitably.

As an example of a resistive touch sensor, a pair of substrates opposed to each other, an insulating spacer sandwiched between the pair of substrates, a transparent conductive film provided as a resistive film on the entire inner surface of each substrate, and a touch position The member comprised by the detection circuit is mentioned. In an image display device provided with a resistive touch sensor, when the surface of the front plate is touched, the opposing resistive film is 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.

As an example of the capacitive coupling type touch sensor, the member comprised by the board|substrate, the transparent electrode for position detection provided on the front surface of the board|substrate, and a touch position detection circuit is mentioned. In an image display device provided with a capacitive coupling type touch sensor, 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, preferably 5 µm or more and 100 µm or less, more preferably 5 µm or more and 50 µm or less, and may be 5 µm or more and 20 µm or less.

The touch sensor panel may be a member in which the pattern of the touch sensor was formed on the base film. The illustration of the base film may be the same as the illustration in description of the above-mentioned thermoplastic resin film. In addition, the touch sensor panel may be transcribe|transferred by the to-be-adhered body from a base film through an adhesive layer. That is, the touch sensor panel does not need to have a base film. The thickness of the touch sensor pattern may be, for example, 1 µm or more and 20 µm or less.

[Method for producing optical laminate]

The optical laminated body 100 can be manufactured according to the method including the process of bonding the layers which comprise the optical laminated body 100 through an adhesive layer. When bonding layers together through an adhesive layer or a bonding layer, it is preferable to perform surface activation processing, such as a corona treatment, with respect to one or both of bonding surfaces for the purpose of adjusting adhesive force. The conditions of a corona treatment can be set suitably, and conditions may differ from one surface of a bonding surface and another surface.

[Display device]

The display device according to the present invention includes the optical laminate 100 . A display apparatus is not specifically limited, For example, image display apparatuses, such as an organic EL display apparatus, an inorganic EL display apparatus, a liquid crystal display apparatus, an electroluminescent display apparatus, are mentioned. A touch sensor may be further laminated|stacked on the optical laminated body, and a display apparatus may have a touchscreen function. The display device including the optical laminate 100 of the present invention is excellent in bending durability and can be used as a flexible display capable of bending or winding.

In the display device, the optical laminate 100 is disposed on the viewing side of the display element included in the display device with the front plate 101 facing outward (the side opposite to the display element side, that is, the viewing side). The display device can be bent with the front plate 101 side inside or outside.

As an image display element which an image display device has, an organic electroluminescent display element, an inorganic electroluminescent display element, a liquid crystal display element, a plasma display element, a field emission type display element etc. are mentioned, for example.

The display device according to the present invention can be used as a mobile device such as a smart phone or tablet, a television, a digital photo frame, an electronic signage, a measuring instrument or instrument, an office device, a medical device, a computer device, and the like.

Example

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

[How to measure]

The measuring method and calculation method of each physical property value (thickness of a layer, the property of an adhesive layer) used for this Example are as follows.

<thickness of layer>

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

<Slope from the origin to the maximum stress value in the stress-strain curve G _L '>

The slope from the origin to the maximum stress value was measured by performing a tensile test using a dynamic mechanical analyzer (DMA, Q-800, manufactured by TA Instruments). First, as shown in FIG. 2, the test piece which joined the edge part of the two polycarbonate (PC) bars 501 through the adhesive layer 502 was prepared. 2 is a cross-sectional view of a test piece. The shape of the pressure-sensitive adhesive layer 502 had a width×length×thickness of 6 mm×10 mm×25 μm, and the shape of the PC bar 501 had a width×length×thickness of 6 mm×20 mm×1 mm. The adhesion area between the pressure-sensitive adhesive layer 502 and the PC bar 501 had a width×length of 6 mm×10 mm. A jig was installed in the area of 5 mm in length of both ends of the PC bar 501 of the test piece, and one jig (the area in which the upper end was 5 mm in length in the test piece of FIG. 2) was fixed. The other jig (a region with a length of 5 mm at the lower end of the test piece in Fig. 2) was pulled at a speed of 100 µm/min in an environment of -40°C to create a stress [Pa]-strain [%] curve. From the obtained stress-strain curve, the slope G _L ' from the origin to the maximum stress was calculated.

[Preparation of the pressure-sensitive adhesive sheet containing the pressure-sensitive adhesive layer]

In a 1 L reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer and a stirrer, 2-ethylhexyl acrylate (2-EHA), butyl acrylate (BA), 2-propyl heptyl acrylate ( 2-PHA) and a monomer mixture solution of acrylic acid (AA) were added. Nitrogen gas was refluxed for 1 hour to remove oxygen in the vessel, and the internal temperature was maintained at 60°C. After uniformly mixing the monomer mixture solution, a photoinitiator benzyl dimethyl ketal (I-651) and 1-hydroxycyclohexylphenyl ketone (I-184) were added in the amounts shown in Table 1. A UV lamp (10 mW) was irradiated while stirring, and (meth)acrylic polymers A1 to A4 were prepared.

The obtained (meth)acrylic polymers A1 to A4, isodecyl acrylate (IDA), hydroxyethyl caprolactone acrylate (HECLA), and 1-hydroxycyclohexylphenyl ketone (I-184) were mixed in the amount shown in Table 2. , pressure-sensitive adhesive compositions B1 to B8 were prepared.

The pressure-sensitive adhesive compositions B1 to B8 were applied to a thickness of 25 µm on a release film A (polyethylene terephthalate film, 38 µm in thickness) coated with a silicone release agent. The release film B (polyethylene terephthalate film, 38 micrometers in thickness) was bonded together on it, UV irradiation was performed, and the adhesive sheet which consists of release film A/adhesive layer/peelable film B was produced. The UV irradiation conditions were an accumulated light quantity of 400 mJ/cm 2 and an illuminance of 1.8 mW/cm 2 (based on UVV). Table 2 shows _{the slope G L} ′ from the origin to the maximum stress value in the stress-strain curve obtained by subjecting the pressure-sensitive adhesive layer to a tensile test.

The source of acquisition of the used compound is as follows.

2-EHA: Tokyo Chemical Industry Co., Ltd., Japan

BA: Tokyo Chemical Industry Co., Ltd., Japan

2-PHA: BASF, Germany

AA：Tokyo Chemical Industry Co., Ltd., Japan

I-651: BASF, Germany

I-184: BASF, Germany

IDA: Tokyo Chemical Industry Co., Ltd., Japan

HECLA: BASF, Germany

[Front panel]

As the front plate 101, a film in which a hard coat layer was formed on one surface of the resin film was prepared. The resin film was a 40-micrometer-thick polyimide-type resin film. The hard-coat layer was 10 micrometers in thickness and was a layer formed from the composition containing the dendrimer compound which has a polyfunctional acryl group at the terminal.

[Polarizer]

A circularly polarizing plate was prepared as the polarizing plate 103 . A linear polarizing plate having a triacetyl cellulose (TAC) film (KC2UA, manufactured by Konica Minolta, Inc., 25 μm thick), an alignment film, a polarizer layer, and an overcoat layer in this order was prepared. The polarizer layer was formed using the composition containing a polymeric liquid crystal compound and a dichroic dye, and thickness was 2 micrometers. The overcoat layer was a polyvinyl alcohol resin layer, and thickness was 1.0 micrometer.

A phase difference laminate was laminated|stacked on the overcoat layer side of a linear polarizing plate through an adhesive layer, and the circularly polarizing plate was obtained. The retardation layered product had a λ/4 retardation layer, an adhesive layer, and a positive C layer in order from the linear polarizing plate side. The λ/4 phase difference layer was a cured layer of a polymerizable liquid crystal compound, and had a thickness of 3 µm. The pressure-sensitive adhesive layer had a thickness of 5 µm. The positive C layer was a cured layer of a polymerizable liquid crystal compound, and had a thickness of 3 µm.

[Backboard]

As the back plate 105, a touch sensor panel in which a touch sensor pattern layer, an adhesive layer, and a base layer were laminated in this order was prepared. The touch sensor pattern layer included an ITO layer as a transparent conductive layer and a cured layer of an acrylic resin composition as a separation layer, and had a thickness of 7 µm. The adhesive layer was provided on the separation layer side of the touch sensor pattern layer and had a thickness of 3 µm. The cyclic olefin resin (COP) film (ZF-14, ZEON CORPORATION (Japan) make, 23 micrometers in thickness) was used for the base material layer.

[Production of optical laminate]

As shown in Table 3, the pressure-sensitive adhesive sheet composed of the pressure-sensitive adhesive composition shown in Table 2 was used as the first pressure-sensitive adhesive layer 102 , and the side without the hard coat layer of the front plate 101 and the TAC film side of the polarizing plate 103 . was pasted together. Moreover, as shown in Table 3, the adhesive sheet which consists of the adhesive composition shown in Table 2 was used as the 2nd adhesive layer 104, and the retardation layer side of a circularly polarizing plate and the touch sensor pattern layer side of a touch sensor panel were bonded together. The optical laminated body 100 (Examples 1-6 and Comparative Examples 1-2) which has the layer structure shown in FIG. 1 was obtained. The double-sided corona treatment was performed to the bonding surface of a front plate, a circularly polarizing plate, a touch sensor panel, and an adhesive layer before bonding. TEC-4AX (made by USHIO INC.) was used for corona treatment.

About the produced optical laminated body 100, the following bending|flexion test was performed. A result is shown in Table 3.

<Bending Test>

About the optical laminated body, the evaluation test which confirms 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 601, 602 that can be moved individually are arranged so that the gap C is 5 mm (bending radius 2.5 mm) or the gap C is 3 mm (bending radius 1.5 mm), The optical laminate was fixed and arranged so that the center of the width direction was positioned at the center of the gap C, and the front plate was positioned on the upper side (FIG. 3(a)). Then, the two mounting tables 601 and 602 were rotated 90 degrees upwardly at positions P1 and P2 as the centers of rotation axes, and a bending force was added to the region of the laminate corresponding to the gap C of the mounting table (FIG. 3). (b)). After that, the two mounting tables 601 and 602 were returned to their original positions (FIG. 3(a)). After completing the above series of operations, the number of times of adding the bending force was counted once. After repeating this at the temperature of -20 degreeC, the presence or absence of generation|occurrence|production of the crack in the adhesive layer in the area|region corresponding to the clearance gap C of the mounting table 601, 602 of the optical laminated body 100 was confirmed. The moving speed of the mounting tables 601 and 602 and the additional pace of the bending force were made into the same conditions also in the evaluation test with respect to any optical laminated body.

A: Cracks did not occur even when the number of times of applying the bending force reached 50,000.

B: Cracks occurred when the number of times of applying the bending force was 20,000 or more and less than 50,000.

C: The crack generate|occur|produced when the number of times of addition of bending force was 10,000 or more and less than 20,000.

D: Cracks occurred when the number of times of applying the bending force was less than 10,000.

100 optical laminate,
101 front panel,
102 first adhesive layer;
103 polarizer,
104 second adhesive layer;
105 backplate,
501 polycarbonate bar,
502 adhesive layer,
601, 602 wit,

Claims (5)

A front plate, a first adhesive layer, a polarizing plate, a second adhesive layer, and a rear plate are provided in this order,
The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer, when the slope from the origin to the maximum stress value in the stress [Pa]-strain [%] curve at a temperature of -40 ° C is G _L1 ' and G _L2 ', respectively. , The optical laminate which satisfy|fills following formula (1) and Formula (2).
100≤G _L1 '≤1000 (1)
100≤G _L2 '≤1000 (2) According to claim 1,
The optical laminated body which satisfy|fills following formula (1') and Formula (2').
300≤G _L1 '≤600 (1')
300≤G _L2 '≤600 (2') 3. The method of claim 1 or 2,
The said back plate is a touch sensor panel, The optical laminated body. A display device comprising the optical laminate according to any one of claims 1 to 3. 5. The method of claim 4,
A display device capable of being bent with the front plate side inside.

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