WO2021085000A1

WO2021085000A1 - Optical laminate and display device

Info

Publication number: WO2021085000A1
Application number: PCT/JP2020/036643
Authority: WO
Inventors: 大山姜; ボラム片
Original assignee: 住友化学株式会社
Priority date: 2019-10-28
Filing date: 2020-09-28
Publication date: 2021-05-06
Also published as: TW202117364A; JP2021071713A; KR20220088414A; CN114641814A

Abstract

The purpose of the present invention is to provide an optical laminate and a display device having excellent bendability and excellent impact resistance. An optical laminate according to the present invention is provided with a front plate, a third adhesive layer, a protective film, a second adhesive layer, a polarizing layer, a first adhesive layer, and a touch sensor layer in this order from a viewing side, and has an impact resistance index A represented by a formula (1) of 200 or more. [In the formula, t_n represents the thickness (μm) of an n-th adhesive layer from the touch sensor layer, G'_n represents a storage elastic modulus (MPa) at 25℃ of the n-th adhesive layer from the touch sensor layer, and a_n represents a value obtained by dividing a distance (μm) from the upper surface of the touch sensor layer to the lower surface of the n-th adhesive layer by t_n.]

Description

Optical laminate and display device

The present invention relates to an optical laminate and a display device, and more particularly to an optical laminate that covers the display surface of a flexible display panel, and a flexible display device having the optical laminate.

In recent years, flexible flexibility display devices have been attracting attention. The flexibility display device can be installed on a non-planar surface such as a curved surface and a bending surface. Further, the flexibility display device can be folded or shaped into a scroll to improve portability. In such a flexibility display device, the optical laminate covering the display surface is also required to have flexibility.

Patent Document 1 includes a first base film, a hard coat layer located on one surface of the first base film, and a second base film located on the other surface. Laminated films that are preferably applicable to cover window substrates are described (summary). The laminated film of Patent Document 1 has a high surface hardness and excellent scratch resistance.

Patent Document 2 describes a transparent window that covers the display surface of the flexible display. The window has a bendable glass layer and a functional coating layer that is located between the glass layer and the display panel and has a lower elastic modulus than the glass layer (summary). Since the window of Patent Document 2 has a glass layer, the surface hardness is high and the scratch resistance is excellent. In addition, the functional coating layer cancels out the tensile stress generated in the glass layer when an impact is applied to a part of the glass layer to prevent the glass layer from being damaged (paragraph [0086]).

Patent Document 3 describes a cover window in which a folding pattern having a large number of concave shapes is formed in a bent portion (claim 1). Since the bendable portion of the cover window is provided with such a bend pattern, it can be thinly deformed and easily bends. In the cover window of Patent Document 3, the bendability is ensured by the presence of the bend pattern in the bendable portion, so that the non-foldable portion can be formed relatively thick with a material having high rigidity, and has high resistance. Impact resistance can also be ensured (paragraph [0009]).

Japanese Unexamined Patent Publication No. 2017-13492 U.S. Patent Publication No. 2018/0034001 Korean Patent Publication No. 10-2018-0079093

Among the display devices, the touch panel is operated by touching the surface of the display device. Depending on the type of operation, the surface of the display device may not only be rubbed but also struck. When the device is dropped, an object may hit the surface of the display device. Therefore, the display device is required to have impact resistance that can withstand not only friction against the surface but also a force suddenly applied in the vertical direction from the viewing side.

The laminated film of Patent Document 1 does not take into consideration the force applied in the vertical direction from the viewing side to the display device, and the impact resistance is still insufficient.

Further, the glass used for the window of Patent Document 2 is a material having inferior flexibility, and as long as it has a glass layer, the window of Patent Document 2 has insufficient flexibility.

Further, with respect to Patent Document 3, the work of specifying a portion where the film is bent and forming a large number of concave shapes is complicated, and the manufacturing cost is high. When a pattern is formed on a part of the optical film, the light transmittance of that part changes, and the versatility as a film material also decreases. Further, since it is necessary to have flexibility in the state where the bent pattern is formed, the rigidity of the material cannot be increased so much, and it is difficult to realize sufficiently high impact resistance.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an optical laminate having excellent flexibility and excellent impact resistance. It is also an object of the present invention to provide a display device having the optical laminate and having excellent flexibility and excellent impact resistance.

The present invention is an optical laminate including a front plate, a third pressure-sensitive adhesive layer, a protective film, a second pressure-sensitive adhesive layer, a polarizing layer, a first pressure-sensitive adhesive layer, and a touch sensor layer in this order from the viewing side.
Over 200 formulas

Wherein, t _n is the thickness of the n-th of the pressure-sensitive adhesive layer from the touch sensor layer represents ([mu] m), G _'n is a storage modulus at 25 ° C. for n-th of the pressure-sensitive adhesive layer from the touch sensor layer ( represents MPa), a _n denotes a value distance ([mu] m) divided by t _n from the touch sensor layer top surface to the n-th of the pressure-sensitive adhesive layer lower surface. ]

Provided is an optical laminate having an impact resistance index A represented by.

In one form, the optical laminate has an impact resistance index A of 2000 or more.

In one form, the first, second and third pressure-sensitive adhesive layers have a thickness of 3-100 μm.

In one embodiment, the first, second and third pressure-sensitive adhesive layers have a storage elastic modulus at a temperature of 0.005 to 1.0 MPa at 25 ° C.

In one embodiment, the first, second and third pressure-sensitive adhesive layers include a pressure-sensitive adhesive composition using a (meth) acrylic resin as a base polymer.

In one form, the first, second and third pressure-sensitive adhesive layers further include a cross-linking agent.

The present invention also provides any of the above optical laminates applied to the display surface of the display panel.

The present invention also provides a display device having a display panel and any of the above optical laminates applied to the display surface of the display panel.

According to the present invention, an optical laminate and a display device having excellent flexibility and excellent impact resistance are provided.

It is sectional drawing which shows an example of the structure of the optical laminated body of this invention. It is sectional drawing which shows an example of the structure of the polarizing layer used for the optical laminated body of this invention. It is sectional drawing which shows an example of the structure of the touch sensor layer used for the optical laminated body of this invention. It is sectional drawing which shows an example of the structure of the display device of this invention.

[Optical laminate]
FIG. 1 is a cross-sectional view showing an example of the structure of the optical laminate of the present invention. The optical laminate 100 shown in FIG. 1 visually recognizes the front plate 10, the third adhesive layer 20, the protective film 30, the second adhesive layer 40, the polarizing layer 50, the first adhesive layer 60, and the touch sensor layer 70. Prepare in this order from the side.

It is preferable that the optical laminate 100 can be bent at least in the direction in which the front plate 10 is inside. Bendable means that the front plate 10 can be bent in the direction inward without causing cracks. The optical laminate according to the present invention is excellent in impact resistance, and can be considered to be excellent in impact resistance as well as bending resistance. In one embodiment, the optical laminate 100 is preferably bendable in the direction in which the front plate 10 is outward. In this case, "flexible" means that the front plate 10 can be bent in the outward direction without causing cracks.

The shape of the optical laminate in the plane direction may be, for example, a square shape, preferably a square shape having a long side and a short side, and more preferably a rectangle. When the shape of the optical laminate in the plane direction is rectangular, the length of the long side may be, for example, 10 to 1400 mm, preferably 50 to 600 mm. The length of the short side is, for example, 5 to 800 mm, preferably 30 to 500 mm, and more preferably 50 to 300 mm. Each layer constituting the optical laminate may have corners R-processed, end portions notched, or perforated.

The thickness of the optical laminate is not particularly limited because it varies depending on the function required for the optical laminate, the application of the laminate, and the like, but is, for example, 20 to 1,000 μm, preferably 50 to 500 μm.

[Front plate]
The front plate 10 constitutes the outermost surface of the optical laminate when viewed from the visual side.

The material and thickness of the front plate 10 are not limited as long as it is a plate-like body capable of transmitting light, and the front plate 10 may be composed of only one layer or may be composed of two or more layers. Examples thereof include a resin plate-like body (for example, a resin plate, a resin sheet, a resin film, etc.) and a glass plate-like body (for example, a glass plate, a glass film, etc.).

The thickness of the front plate 10 may be, for example, 30 to 2,000 μm, preferably 50 to 1,000 μm, more preferably 50 to 500 μm, and further preferably 50 to 100 μm.

The tensile elastic modulus of the front plate 10 is preferably 3 GPa or more, more preferably 4 GPa or more, and further preferably 5 GPa or more. The tensile elastic modulus of the front plate 10 is preferably 10 GPa or less, more preferably 9 GPa or less. When the tensile elastic modulus is at least the above lower limit value, defects such as dents are less likely to occur in the front plate when an impact is received from the outside, and the strength of the front plate is likely to be increased. Further, when the tensile elastic modulus is not more than the above upper limit value, it is easy to improve the bending resistance of the front plate. The tensile elastic modulus may satisfy at least one of MD (Machine Direction, film forming direction) or TD (Transverse Direction, direction perpendicular to MD), and it is preferable that both of them satisfy the above range.

When the front plate 10 is a resin plate-like body, the material may be, for example, an acrylic resin such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; and a polyolefin-based material such as polyethylene, polypropylene, polymethylpentene and polystyrene. Resins: Cellular resins such as triacetyl cellulose, acetyl cellulose butyrate, propionyl cellulose, butyryl cellulose and acetyl propionyl cellulose; ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, etc. Polyvinyl resin; sulfone resin such as polysulfone and polyether sulfone; ketone resin such as polyether ketone and polyether ether ketone; polyetherimide; polycarbonate resin; polyester resin; polyimide resin; polyamideimide resin; And polyamide resin and the like. These polymers can be used alone or in admixture of two or more. Above all, from the viewpoint of improving strength and transparency, it is preferable to use a polycarbonate resin, a polyester resin, a polyimide resin, a polyamide-imide resin, or a polyamide resin. The thickness of the resin plate-like body may be, for example, 30 to 2,000 μm, preferably 50 to 1,000 μm, more preferably 50 to 500 μm, and may be 100 μm or less.

The front plate 10 may be a film having a hard coat layer provided on at least one surface of the base film to further improve the hardness. As the base film, a film made of the above resin can be used. The hard coat layer may be formed on one surface of the base film or may be formed on both surfaces. By providing the hard coat layer, a resin film having improved hardness and scratchability can be obtained. The hard coat layer is, for example, a cured layer of an ultraviolet curable resin. Examples of the ultraviolet curable resin include acrylic resin, silicone resin, polyester resin, urethane resin, amide resin, epoxy resin and the like. The hard coat layer may contain additives to improve strength. Additives are not limited, and examples thereof include inorganic fine particles, organic fine particles, and mixtures thereof.

When the front plate 10 is a glass plate, tempered glass for a display is preferably used as the glass plate. The thickness of the glass plate may be, for example, 50 to 1,000 μm. By using the glass plate, the front plate 10 having excellent mechanical strength and surface hardness can be constructed.

When the optical laminate is used in the display device, the front plate 10 may have a function as a window film in the display device. The front plate 10 may further have a function as a touch sensor, a blue light cut function, a viewing angle adjusting function, and the like.

[Adhesive layer]
The pressure-sensitive adhesive layer includes a third pressure-sensitive adhesive layer 20 located between the front plate 10 and the protective film 30, a second pressure-sensitive adhesive layer 40 located between the protective film 30 and the polarizing layer 50, and the polarizing layer 50. It is composed of a first adhesive layer 60 located between the touch sensor layer 70 and the touch sensor layer 70. More specifically, the third adhesive layer 20 is an adhesive layer in contact with the front plate 10 and the protective film 30, and the second adhesive layer 40 is an adhesive in contact with the protective film 30 and the polarizing layer 50. The first pressure-sensitive adhesive layer 60 is a pressure-sensitive adhesive layer that is in contact with the polarizing layer 50 and the touch sensor layer 70. Each pressure-sensitive adhesive layer may be made of the same material or different materials.

The pressure-sensitive adhesive layer can be composed of a pressure-sensitive adhesive composition containing a resin as a main component, such as (meth) acrylic-based, rubber-based, urethane-based, ester-based, silicone-based, and polyvinyl ether-based. Among them, a pressure-sensitive adhesive composition using a (meth) acrylic resin having excellent transparency, weather resistance, heat resistance and the like as a base polymer is preferable. The pressure-sensitive adhesive composition may be an active energy ray-curable type or a thermosetting type.

Examples of the (meth) acrylic resin (base polymer) used in the pressure-sensitive adhesive composition include butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, and 2- (meth) acrylate. A polymer or copolymer containing one or more (meth) acrylic acid esters such as ethylhexyl as a monomer is preferably used. It is preferable that the base polymer is copolymerized with a polar monomer. Examples of the polar monomer include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, and glycidyl (). Examples thereof include monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group and the like, such as meta) acrylate.

The pressure-sensitive adhesive composition may contain only the above-mentioned base polymer, but usually further contains a cross-linking agent. The cross-linking agent is a divalent or higher metal ion that forms a carboxylic acid metal salt with a carboxyl group; a polyamine compound that forms an amide bond with a carboxyl group; poly. Examples include epoxy compounds and polyols that form an ester bond with a carboxyl group; polyisocyanate compounds that form an amide bond with a carboxyl group. Of these, polyisocyanate compounds are preferable.

The active energy ray-curable pressure-sensitive adhesive composition has a property of being cured by being irradiated with active energy rays such as ultraviolet rays and electron beams, and has adhesiveness even before irradiation with active energy rays. It is a pressure-sensitive adhesive composition having the property of being able to adhere to an adherend such as, etc., and being cured by irradiation with active energy rays to adjust the adhesion force. The active energy ray-curable pressure-sensitive adhesive composition is preferably an ultraviolet-curable type. The active energy ray-curable pressure-sensitive adhesive composition further contains an active energy ray-polymerizable compound in addition to the base polymer and the cross-linking agent.
Further, if necessary, a photopolymerization initiator, a photosensitizer, or the like may be contained.

The pressure-sensitive adhesive composition includes fine particles for imparting light scattering, beads (resin beads, glass beads, etc.), glass fibers, resins other than the base polymer, pressure-sensitive adhesives, fillers (metal powders and other inorganic powders). Etc.), antioxidants, UV absorbers, dyes, pigments, colorants, antifoaming agents, corrosion inhibitors, photopolymerization initiators and other additives may be included.

It can be formed by applying an organic solvent diluent of the above pressure-sensitive adhesive composition on a substrate and drying it. When the active energy ray-curable pressure-sensitive adhesive composition is used, the formed pressure-sensitive adhesive layer can be irradiated with active energy rays to obtain a cured product having a desired degree of curing.

The adhesive layer has high viscoelasticity and has a function of alleviating the impact applied to the optical laminate. In the optical laminate of the present invention, the impact resistance of the optical laminate to the impact applied to the outermost surface of the optical laminate is improved by appropriately adjusting the characteristics of the pressure-sensitive adhesive layer. That is, even when an impact is applied to the surface of the optical laminate, the wiring and elements of the touch sensor layer and the display panel covered by the optical laminate are less likely to be damaged.

The inventor's study revealed that the elasticity, thickness and position of the pressure-sensitive adhesive layer are related to the impact resistance of the optical laminate. The impact mitigation effect of the pressure-sensitive adhesive layer increases as the elastic modulus of the pressure-sensitive adhesive layer decreases. Further, the impact mitigation effect of the pressure-sensitive adhesive layer increases as the pressure-sensitive adhesive layer becomes thicker. The impact mitigation effect of the pressure-sensitive adhesive layer becomes more effective as the position of the pressure-sensitive adhesive layer is closer to the display panel.

Here, the elastic modulus of the pressure-sensitive adhesive layer is represented by the storage elastic modulus G'(MPa). The thickness of the pressure-sensitive adhesive layer is represented by an actually measured value t (μm). The elastic modulus and thickness of the pressure-sensitive adhesive layer can be specified for each layer using these characteristic values.

The position of the pressure-sensitive adhesive layer from the display panel is closest to the first pressure-sensitive adhesive layer, and is farther from the second pressure-sensitive adhesive layer and the third pressure-sensitive adhesive layer in that order. Each pressure-sensitive adhesive layer has its own thickness, and the thickness is independently determined as appropriate. Therefore, it is difficult to indicate the position of the pressure-sensitive adhesive layer with respect to the display panel by determining the reference part and simply comparing the distances from the reference part of the lowest layer to the reference part of each pressure-sensitive adhesive layer.

Therefore, how far the target adhesive layer is from the display panel is indicated by the distance d (μm) from the upper surface of the touch sensor layer, which is the lowest layer, to the side surface (lower surface) of the display panel of the target adhesive layer. In order to eliminate the influence of the thickness of the pressure-sensitive adhesive layer, the characteristic value a obtained by dividing the above distance by the thickness t (μm) of the target pressure-sensitive adhesive layer is defined. The characteristic value a = d / t represents how far it is from the display panel when the target pressure-sensitive adhesive layer having a unit thickness is assumed. The a of the first pressure-sensitive adhesive layer is defined as 1.

Expressing the superiority or inferiority of the impact mitigation performance of the pressure-sensitive adhesive layer using these characteristic values, it is inversely proportional to the elastic modulus G'of the pressure-sensitive adhesive layer, proportional to the thickness t of the pressure-sensitive adhesive layer, and the distance from the display panel. It is inversely proportional to a. Then, t / (a × G') can be considered as a characteristic value representing the impact mitigation performance of the pressure-sensitive adhesive layer. By summing the above characteristic values of the first pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer, and the third pressure-sensitive adhesive layer, a characteristic value representing the impact mitigation performance of the entire optical laminate can be obtained. Hereinafter, this characteristic value will be referred to as an impact resistance index A.

Although the adhesive layer may be present inside the polarizing layer and the touch sensor layer, it is considered that the impact resistance of the optical laminate is not affected because the thickness is usually as thin as 5 μm or less. Therefore, when calculating the impact resistance index A, the pressure-sensitive adhesive layer inside the polarizing layer and the pressure-sensitive adhesive layer inside the touch sensor layer are not taken into consideration.

In an optical laminate having a front plate, a third pressure-sensitive adhesive layer, a protective film, a second pressure-sensitive adhesive layer, a polarizing layer, a first pressure-sensitive adhesive layer, and a touch sensor layer in this order from the visual side, the superiority or inferiority of impact mitigation performance is It has a correlation with the value of the impact resistance index A. That is, in a layer structure having a protective film between the front plate and the polarizing layer, the superiority or inferiority of the impact mitigation performance has a correlation with the value of the impact resistance index A. The optical laminate of the present invention has 200 or more A's. As a result, good impact mitigation performance of the optical laminate is achieved while having durability against bending.

In one embodiment, the A of the optical laminate is preferably 266 or greater, more preferably 500 or greater, more preferably 1500 or greater, even more preferably 2000 or greater, even 2500 or greater. Good. In another embodiment, the A of the optical laminate is preferably 250 or more, more preferably 266 or more, more preferably 500 or more, more preferably 1500 or more, and even more preferably 2000 or more. It may be 2500 or more.

In one form, the A of the optical laminate may be, for example, 6000 or less, preferably 5000 or less, and more preferably 4658 or less. In another embodiment, the A of the optical laminate may be, for example, 6000 or less, preferably 5000 or less, more preferably 4800 or less, more preferably 4658 or less, and 4000 or less. You may.

A of the optical laminate is preferably 2013 to 4658. If the amount of A of the optical laminate exceeds 6000, peeling / coagulation failure may occur at the interface between the pressure-sensitive adhesive layer and another member or inside the pressure-sensitive adhesive layer at the time of bending.

In a preferred embodiment, the thickness of the first, second and third pressure-sensitive adhesive layers is appropriately selected from the range of 3 to 100 μm. If the pressure-sensitive adhesive layer is too thin, the impact resistance of the optical laminate is reduced. If the pressure-sensitive adhesive layer is too thick, the flexibility of the optical laminate is reduced. The thickness of the first, second and third pressure-sensitive adhesive layers is preferably 5 to 70 μm, more preferably 10 to 50 μm.

In a preferred embodiment, the storage elastic modulus of the first, second and third pressure-sensitive adhesive layers at a temperature of 25 ° C. is appropriately selected from the range of 0.005 to 1.0 MPa. If the storage elastic modulus is too low, the impact resistance of the optical laminate is reduced. If the storage elastic modulus of the first, second and third pressure-sensitive adhesive layers is too high, the flexibility of the optical laminate is reduced. The storage elastic modulus of the first, second and third pressure-sensitive adhesive layers is preferably 0.01 to 0.5 MPa, more preferably 0.01 to 0.2 MPa. Further, in another embodiment, the storage elastic modulus of the first, second and third pressure-sensitive adhesive layers is preferably 0.01 to 0.1 MPa, more preferably 0.02 to 0.09 MPa. , 0.02 to 0.06 MPa may be used.

[Protective film]
The protective film 30 is located between the third pressure-sensitive adhesive layer 20 and the second pressure-sensitive adhesive layer 40. The protective film can contribute to the improvement of the impact resistance of the optical laminate. The protective film 30 can also function as a protective layer that protects the polarizing layer 50.

The tensile elastic modulus of the protective film 30 is preferably 3 GPa or more, more preferably 4 GPa or more, and further preferably 5 GPa or more. The tensile elastic modulus of the protective film 30 is preferably 10 GPa or less, more preferably 9 GPa or less. When the tensile elastic modulus is at least the above lower limit value, the impact resistance of the optical laminate is likely to be improved when an impact is received from the outside. Further, when the tensile elastic modulus is not more than the above upper limit value, the bending resistance of the protective film 30 is likely to be improved. The tensile elastic modulus may satisfy at least one of MD (Machine Direction, film forming direction) or TD (Transverse Direction, direction perpendicular to MD), and it is preferable that both of them satisfy the above range.

As the material of the protective film 30, for example, a translucent (preferably optically transparent) thermoplastic resin, for example, a chain polyolefin resin (polypropylene resin or the like), a cyclic polyolefin resin (norbornen resin, etc.) Etc.), polyolefin resins such as cellulose triacetate, cellulose ester resins such as cellulose diacetate, polyester resins, polycarbonate resins, (meth) acrylic resins, polystyrene resins, or mixtures and copolymers thereof. Etc. can be used.

Further, the protective film 30 may be a protective film having an optical function such as a retardation film or a brightness improving film. For example, a retardation film to which an arbitrary retardation value is imparted by stretching a film made of the thermoplastic resin (uniaxial stretching, biaxial stretching, etc.) or forming a liquid crystal layer or the like on the film. Can be.

Examples of the chain polyolefin resin include homopolymers of chain olefins such as polyethylene resin and polypropylene resin, and copolymers composed of two or more kinds of chain olefins.

Cyclic polyolefin resin is a general term for resins that are polymerized using cyclic olefin as a polymerization unit. Specific examples of the cyclic polyolefin resin include, for example, a ring-opening (co) polymer of a cyclic olefin, an addition polymer of a cyclic olefin, and a copolymer of a cyclic olefin and a chain olefin such as ethylene or propylene (typical). Examples thereof include random copolymers), graft polymers obtained by modifying them with unsaturated carboxylic acids and derivatives thereof, and hydrides thereof. Among them, as the cyclic olefin, a norbornene-based resin using a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer is preferably used.

Cellulose ester-based resins are esters of cellulose and fatty acids. Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate.
Further, these copolymers and those in which some of the hydroxyl groups are modified with other substituents can also be used. Of these, cellulose triacetate (triacetyl cellulose: TAC) is particularly preferable.

The polyester-based resin is a resin other than the above-mentioned cellulose ester-based resin having an ester bond, and is generally composed of a polyvalent carboxylic acid or a polycondensate of a derivative thereof and a polyhydric alcohol. As the polyvalent carboxylic acid or a derivative thereof, a dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylic acid. As the polyhydric alcohol, a diol can be used, and examples thereof include ethylene glycol, propanediol, butanediol, neopentyl glycol, cyclohexanedimethanol and the like.

Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexanedimethylterephthalate, and polycyclohexanedimethylnaphthalate. Can be mentioned.

Polycarbonate-based resin consists of a polymer in which monomer units are bonded via a carbonate group. The polycarbonate-based resin may be a resin called modified polycarbonate having a modified polymer skeleton, a copolymerized polycarbonate, or the like.

The (meth) acrylic resin is a resin whose main constituent monomer is a compound having a (meth) acryloyl group. Specific examples of the (meth) acrylic resin include poly (meth) acrylic acid esters such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymers, and methyl methacrylate- (meth) acrylic. Acid ester copolymer, methyl methacrylate-acrylic acid ester- (meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), methyl methacrylate and alicyclic hydrocarbon group (For example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.) is included. Preferably, a polymer containing a poly (meth) acrylic acid C1-6 alkyl ester as a main component, such as methyl poly (meth) acrylate, is used. More preferably, a methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is used.

The thickness of the protective film 30 is preferably 10 μm to 200 μm, more preferably 10 μm to 100 μm, and even more preferably 15 μm to 95 μm. In the protective film 30, the in-plane retardation value Re (550) is, for example, 0 nm to 10 nm, and the thickness direction retardation value Rth (550) is, for example, −80 nm to +80 nm.

[Polarizing layer]
The polarizing layer 50 is located between the second pressure-sensitive adhesive layer 40 and the first pressure-sensitive adhesive layer 60. FIG. 2 is a cross-sectional view showing an example of the structure of the polarizing layer. The polarizing layer 50 shown in FIG. 2 includes a polarizer 51, an adhesive layer 52, a 1/2 wave plate 53, an adhesive layer 54, and a 1/4 wave plate 55 in this order from the visual side. The polarizing layer may be a so-called circular polarizing plate. The thickness of the circularly polarizing plate can be 10 μm to 100 μm, 15 μm to 70 μm, and 20 μm to 50 μm. Within such a range, it is easy to achieve both bending resistance and impact resistance of the optical laminate.

The polarizing layer 50 may have an additional protective film (not displayed) between the polarizing element 51 and the second adhesive layer 40. The additional protective film is composed of a material similar to that exemplified as the material of the protective film 30, and is adhered to the surface of the polarizer 51 via an adhesive layer (hidden).

The polarizer 51 passes linearly polarized light having a polarizing surface in a specific direction, and the light passing through the polarizer 51 becomes linearly polarized light that oscillates in the transmission axis direction of the polarizer. The thickness of the polarizer 51 is, for example, about 1 μm to 80 μm.

Examples of the polarizer 51 include a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene-vinyl acetate copolymerization system partially saponified film, and two such as iodine and a bicolor dye. In addition to those that have been dyed and stretched with a chromatic substance, polyene-based oriented films such as a dehydrated product of polyvinyl alcohol and a dehydrogenated product of polyvinyl chloride can be used. Above all, it is preferable to use a film obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching it as having excellent optical characteristics.

Dyeing with iodine is performed, for example, by immersing a polyvinyl alcohol-based film in an aqueous iodine solution. The draw ratio of uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing treatment or while dyeing. Moreover, you may dye after stretching.

The polyvinyl alcohol-based film is subjected to swelling treatment, cross-linking treatment, cleaning treatment, drying treatment and the like, if necessary. For example, by immersing a polyvinyl alcohol-based film in water and washing it with water before dyeing, not only can the dirt on the surface of the polyvinyl alcohol-based film and the blocking inhibitor be washed, but also the polyvinyl alcohol-based film is swollen and dyed. It is possible to prevent unevenness and the like.

As the polarizing element 51, for example, as described in Japanese Patent Application Laid-Open No. 2016-170368, a cured film in which a liquid crystal compound is polymerized may be used in which a dichroic dye is oriented. As the dichroic dye, a dye having absorption in the wavelength range of 380 to 800 nm can be used, and it is preferable to use an organic dye. Examples of the dichroic dye include an azo compound. The liquid crystal compound is a liquid crystal compound that can be polymerized while being oriented, and can have a polymerizable group in the molecule.

The luminous efficiency correction degree of polarization of the polarizer 51 is preferably 95% or more, and more preferably 97% or more. Further, it may be 99% or more, and may be 99.9% or more. The luminous efficiency correction degree of polarization of the polarizer 51 may be 99.995% or less, and may be 99.99% or less. The luminous efficiency correction polarization degree is a two-degree field of view of "JIS Z 8701" with respect to the obtained polarization degree using an absorptiometer with an integrating sphere ("V7100" (trade name) manufactured by JASCO Corporation). It can be calculated by correcting the visual sensitivity with the C light source).

By setting the luminous efficiency correction polarization degree of the polarizer 51 to 99.9% or more, it becomes easy to adjust the initial hue (before bending) to a position away from neutral. Therefore, regarding the hue of the reflected light before and after bending, which will be described later, the sign of the a * b * chromaticity coordinate is less likely to change with the a * coordinate axis and the b * coordinate axis in between. Further, by setting the luminous efficiency correction degree of polarization of the polarizer 51 to 99.9% or more, the durability of the polarizer 51 can be improved. On the other hand, if the luminous efficiency correction polarization degree of the polarizer 51 is less than 95%, the function as an antireflection film may not be achieved.

The luminous efficiency correction single transmittance of the polarizer 51 is preferably 42% or more, more preferably 44% or more, preferably 60% or less, and further preferably 50% or less. For the luminous efficiency correction single transmittance, a absorptiometer with an integrating sphere (“V7100” (trade name) manufactured by JASCO Corporation) was used, and the two-degree field (C light source) of JIS Z8701 was used with respect to the obtained transmittance. ) Can be calculated by correcting the visual sensitivity.

By setting the luminous efficiency correction orthogonal transmittance of the polarizer 51 to 42% or more, the orthogonal hue of the polarizer 51 can be easily adjusted to a position away from the neutral side, so that the color change becomes inconspicuous before and after bending, which will be described later. It is possible to do. If it exceeds 50%, the degree of polarization becomes too low, and the function as antireflection may not be achieved.

The pressure-sensitive adhesive layer 52 is formed of, for example, an acrylic pressure-sensitive adhesive.

The 1/2 wave plate 53 gives a phase difference of π (= λ / 2) to the electric field vibration direction (polarization plane) of the incident light, and has a function of changing the direction of linearly polarized light (polarization direction). There is. Further, when circularly polarized light is incident, the direction of rotation of circularly polarized light can be reversed.

In the 1/2 wave plate 53, Re (λ), which is an in-plane retardation value at a specific wavelength λ nm, satisfies Re (λ) = λ / 2. This equation may be achieved at any wavelength in the visible light region (eg, 550 nm). Above all, it is preferable that Re (550), which is an in-plane retardation value at a wavelength of 550 nm, satisfies 210 nm ≦ Re (550) ≦ 300 nm. Further, it is more preferable to satisfy 220 nm ≦ Re (550) ≦ 290 nm.

Rth (550), which is a retardation value in the thickness direction of the 1/2 wavelength plate 53 measured at a wavelength of 550 nm, is preferably −150 to 150 nm, and more preferably -100 to 100 nm.

The thickness of the 1/2 wave plate 53 is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 0.5 to 5 μm, and more preferably 0.5, from the viewpoint that the effect of preventing wrinkles is likely to be noticeable. It is more preferably ~ 3 μm. The thickness of the 1/2 wave plate 53 is obtained by measuring the thickness of any five points in the plane and arithmetically averaging them.

The 1/2 wave plate 53 may include a film made of a resin exemplified as a material of the protective film 51 described later, a layer in which a liquid crystal compound is cured, and the like. When the 1/2 wave plate 53 is formed of a resin, a polycarbonate resin, a cyclic olefin resin, a styrene resin, and a cellulosic resin are particularly preferable. In the present embodiment, the 1/2 wavelength plate 53 preferably includes a layer in which the liquid crystal compound is cured. Although the type of the liquid crystal compound is not particularly limited, it can be classified into a rod-shaped type (rod-shaped liquid crystal compound) and a disk-shaped type (disk-shaped liquid crystal compound, discotic liquid crystal compound) according to its shape. Further, there are a low molecular weight type and a high molecular weight type, respectively. The polymer generally refers to a polymer having a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, Masao Doi, 2 pages, Iwanami Shoten, 1992).

In this embodiment, any liquid crystal compound can be used. Further, two or more kinds of rod-shaped liquid crystal compounds, two or more kinds of disk-shaped liquid crystal compounds, or a mixture of a rod-shaped liquid crystal compound and a disk-shaped liquid crystal compound may be used.

As the rod-shaped liquid crystal compound, for example, those described in claim 1 of JP-A-11-513019 or paragraphs [0026] to [00998] of JP-A-2005-289980 are preferably used. it can. As the disk-shaped liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP-A-2007-108732 or paragraphs [0013] to [0108] of JP-A-2010-244038 are preferable. Can be used.

The 1/2 wave plate 53 is more preferably formed by using a liquid crystal compound having a polymerizable group (rod-shaped liquid crystal compound or disk-shaped liquid crystal compound). Thereby, the temperature change and the humidity change of the optical characteristics can be reduced.

The liquid crystal compound may be a mixture of two or more kinds. In that case, it is preferable that at least one has two or more polymerizable groups. That is, the 1/2 wave plate 53 is preferably a layer formed by fixing a rod-shaped liquid crystal compound having a polymerizable group or a disk-shaped liquid crystal compound having a polymerizable group by polymerization, and such a layer is a liquid crystal. The compound is contained in the cured layer.
In this case, it is no longer necessary to exhibit liquid crystallinity after forming a layer.

The type of the polymerizable group contained in the rod-shaped liquid crystal compound or the disk-shaped liquid crystal compound is not particularly limited, and is, for example, a functional group capable of an addition polymerization reaction such as a polymerizable ethylenically unsaturated group or a ring-polymerizable group. Is preferable. More specifically, for example, a (meth) acryloyl group, a vinyl group, a styryl group, an allyl group and the like can be mentioned. Of these, the (meth) acryloyl group is preferable. The (meth) acryloyl group is a concept that includes both a meta-acryloyl group and an acryloyl group.

The method for forming the 1/2 wavelength plate 53 is not particularly limited, and known methods can be mentioned. For example, a composition for forming an optically anisotropic layer (hereinafter, simply referred to as “composition”) containing a liquid crystal compound having a polymerizable group is applied to a predetermined substrate (including a temporary substrate) to form a coating film. Then, the first 1/2 wave plate 53 can be manufactured by subjecting the obtained coating film to a curing treatment (ultraviolet irradiation (light irradiation treatment) or heat treatment).

The composition can be applied by a known method, for example, a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method.

The composition may contain components other than the liquid crystal compounds described above. For example, the composition may contain a polymerization initiator. As the polymerization initiator used, for example, a thermal polymerization initiator or a photopolymerization initiator is selected according to the type of the polymerization reaction. For example, examples of the photopolymerization initiator include α-carbonyl compounds, acyloin ethers, α-hydrocarbon-substituted aromatic acyloin compounds, polynuclear quinone compounds, and combinations of triarylimidazole dimers and p-aminophenyl ketones. The amount of the polymerization initiator used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the total solid content of the composition.

Further, the composition may contain a polymerizable monomer from the viewpoint of the uniformity of the coating film and the strength of the film. Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Of these, a polyfunctional radically polymerizable monomer is preferable.

The polymerizable monomer is preferably copolymerized with the above-mentioned liquid crystal compound containing a polymerizable group. Specific examples of the polymerizable monomer include those described in paragraphs [0018] to [0020] in JP-A-2002-296423. The amount of the polymerizable monomer used is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, based on the total mass of the liquid crystal compound.

Further, the composition may contain a surfactant from the viewpoint of the uniformity of the coating film and the strength of the film. Examples of the surfactant include conventionally known compounds. Of these, fluorine-based compounds are particularly preferable. Specific examples of the surfactant include the compounds described in paragraphs [0028] to [0056] in JP 2001-330725, and paragraphs [0069] to [0126] in Japanese Patent Application No. 2003-295212. ], Examples thereof include the compounds described in.

Further, the composition may contain a solvent, and an organic solvent is preferably used. Examples of the organic solvent include amide (eg, N, N-dimethylformamide), sulfoxide (eg, dimethyl sulfoxide), heterocyclic compound (eg, pyridine), hydrocarbon (eg, benzene, hexane), alkyl halide (eg, eg). , Chloroform, dichloromethane), esters (eg, methyl acetate, ethyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane).
Of these, alkyl halides and ketones are preferable. Further, two or more kinds of organic solvents may be used in combination.

In addition, the composition includes a vertical alignment accelerator such as a polarizer interface side vertical alignment agent and an air interface side vertical alignment agent, and a horizontal alignment accelerator such as a polarizer interface side horizontal alignment agent and an air interface side horizontal alignment agent. Various orienting agents such as may be contained. Further, the composition may contain an adhesion improver, a plasticizer, a polymer and the like in addition to the above components.

The 1/2 wavelength plate 53 may include an alignment film having a function of defining the orientation direction of the liquid crystal compound. The alignment film generally contains a polymer as a main component. The polymer material for an alignment film has been described in a large number of documents, and a large number of commercially available products are available. Among them, it is preferable to use polyvinyl alcohol or polyimide or a derivative thereof as the polymer material, and it is particularly preferable to use modified or unmodified polyvinyl alcohol.

Regarding the alignment film that can be used in this embodiment, the modification described in International Publication No. 2001/88574, p. 43, p. 24 to p. 49, p. 8 and paragraphs [0071] to [0995] of Japanese Patent No. 3907735. Polyvinyl alcohol can be referred to.

The alignment film is usually subjected to a known alignment treatment. For example, a rubbing treatment, a photo-alignment treatment for applying polarized light, and the like can be mentioned, but the photo-alignment treatment is preferable from the viewpoint of the surface roughness of the alignment film.

Although the thickness of the alignment film is not particularly limited, it is often 20 μm or less, and more preferably 0.01 to 10 μm, more preferably 0.01 to 5 μm, and 0.01 to 0.01 to 5 μm. It is more preferably 1 μm.

The 1/4 wave plate 55 gives a phase difference of π / 2 (= λ / 4) to the electric field vibration direction (polarization plane) of the incident light, and linearly polarized light having a specific wavelength is converted to circularly polarized light (or circularly polarized light). It has a function to convert circularly polarized light to linearly polarized light.

In the 1/4 wave plate 55, Re (λ), which is an in-plane retardation value at a specific wavelength λ nm, satisfies Re (λ) = λ / 4. This equation may be achieved at any wavelength in the visible light region (eg, 550 nm). Above all, it is preferable that Re (550), which is an in-plane retardation value at a wavelength of 550 nm, satisfies 100 nm ≦ Re (550) ≦ 160 nm. Further, it is more preferable to satisfy 110 nm ≦ Re (550) ≦ 150 nm.

Rth (550), which is a retardation value in the thickness direction of the 1/4 wave plate 55 measured at a wavelength of 550 nm, is preferably −120 to 120 nm, and more preferably −80 to 80 nm.

The thickness of the 1/4 wave plate 55 is not particularly limited, but is preferably 0.5 to 10 μm, more preferably 0.5 to 5 μm, from the viewpoint of preventing wrinkles due to differences in dimensional changes on the front and back surfaces of the film during bending. It is preferable, and 0.5 to 3 μm is more preferable. The thickness of the 1/4 wave plate 55 is obtained by measuring the thickness of any five points in the plane and arithmetically averaging them.

The 1/4 wave plate 55 preferably contains a layer in which the liquid crystal compound is cured. Although the type of the liquid crystal compound is not particularly limited, the same material as that mentioned as the material of the 1/2 wavelength plate 53 can be used. Above all, it is preferable that the layer is formed by fixing a rod-shaped liquid crystal compound having a polymerizable group or a disk-shaped liquid crystal compound having a polymerizable group by polymerization. In this case, it is no longer necessary to exhibit liquid crystallinity after forming a layer.

Among the layers contained in the polarizer 51, the layer other than the polarizer 51 on which the liquid crystal compound is cured is preferably one layer or two layers. When three or more layers in which the liquid crystal compound is cured are included, the number of layers in which wrinkles may occur increases, and it is considered that wrinkles are likely to occur at the time of bending.

The adhesive layer 54 is an active energy ray-curable adhesive (preferably ultraviolet curable) containing, as an adhesive, a curable compound that is cured by irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. A water-based adhesive in which an adhesive component such as a sex adhesive) or a polyvinyl alcohol-based resin is dissolved or dispersed in water can be used. In the polarizer 51, by laminating the 1/2 wavelength plate 53 and the 1/4 wavelength plate 55 via the adhesive layer 54, it is possible to prevent wrinkles from being generated at the time of bending.

As the active energy ray-curable adhesive, an active energy ray-curable adhesive composition containing a cationically polymerizable curable compound and / or a radically polymerizable curable compound is preferably used because it exhibits good adhesiveness. be able to. The active energy ray-curable adhesive may further contain a cationic polymerization initiator and / or a radical polymerization initiator for initiating the curing reaction of the curable compound.

Examples of the cationically polymerizable curable compound include an epoxy compound (a compound having one or more epoxy groups in the molecule) and an oxetane compound (one or two or more oxetane rings in the molecule). Compounds), or a combination thereof. Examples of the radically polymerizable curable compound include (meth) acrylic compounds (compounds having one or more (meth) acryloyloxy groups in the molecule), radically polymerizable double bonds, and others. Vinyl-based compounds, or combinations thereof. A cationically polymerizable curable compound and a radically polymerizable curable compound may be used in combination.

Active energy ray-curable adhesives include cationic polymerization accelerators, ion trapping agents, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow conditioners, plasticizers, and defoamers, as required. It may contain additives such as foaming agents, antistatic agents, leveling agents, and solvents.

When the 1/2 wave plate 53 and the 1/4 wave plate 55 are bonded together using an active energy ray-curable adhesive, the 1/2 wave plate is passed through the active energy ray-curable adhesive that becomes the adhesive layer 54. After laminating the plate 53 and the 1/4 wave plate, the adhesive layer is cured by irradiating with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. Among them, ultraviolet rays are preferable, and as the light source in this case, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, a metal halide lamp, or the like can be used. When a water-based adhesive is used, the 1/2 wavelength plate 53 and the 1/4 wavelength plate 55 may be laminated via the water-based adhesive and then heat-dried.

The thickness of the adhesive layer 54 is preferably 0.5 to 5 μm, more preferably 0.5 to 3 μm.

The storage elastic modulus of the adhesive layer 54 at a temperature of 30 ° C. is preferably 600 MPa to 4000 MPa, more preferably 700 MPa to 3500 MPa, further preferably 1000 MPa to 3000 MPa, and 1500 MPa to 3000 MPa. Is the most preferable. By adhering the 1/2 wave plate 53 and the 1/4 wave plate 55 with the hard adhesive layer 54 exhibiting such a storage elastic modulus, it is easier to prevent wrinkles from being generated in the retardation layer at the time of bending. it can.

The storage elastic modulus of the adhesive layer 54 at a temperature of 30 ° C. shall be the measured value when the storage elastic modulus of the adhesive layer 54 at a temperature of 30 ° C. in the polarizer 51 can be directly measured by the following method. On the other hand, when direct measurement is not possible, an adhesive layer test piece is formed on the release paper under the same conditions as the formation of the adhesive layer 54 (adhesive type, curing conditions), and the adhesive layer test piece is peeled off from the release paper. It shall be possible to regard the thing as the same value as the storage elasticity measured by the following method.

The storage elastic modulus of the adhesive layer 54 or the adhesive layer test piece can be measured by a commercially available dynamic viscoelastic device, for example, measured by "DVA-220" (trade name) manufactured by IT Measurement Control Co., Ltd. can do.

[Touch sensor layer]
The touch sensor layer 70 is located at the lowest layer when viewed from the visual recognition side. FIG. 3 is a cross-sectional view showing an example of the structure of the touch sensor layer. The touch sensor layer 70 shown in FIG. 3 includes a transparent conductive layer 71, a separation layer 72, an adhesive layer 73, and a base material layer 74 in this order from the visual recognition side.

The touch sensor layer 70 is a sensor capable of detecting the position touched by the front plate 10, and as long as it has a transparent conductive layer 71, the detection method is not limited, and the resistance film method and the capacitance are used. Examples thereof include touch sensor layers such as a capacitance method, an optical sensor method, an ultrasonic method, an electromagnetic induction coupling method, and a surface acoustic wave method. Among them, the capacitance type touch sensor layer is preferably used in terms of low cost, fast reaction speed, and thin film formation. The touch sensor layer 70 includes a base material layer 74 and a transparent conductive layer 71 provided on the surface of the base material layer 74 on the adhesive layer 73 side from the viewpoint of improving impact resistance. It is preferable to have. In the configuration in which the transparent conductive layer 71 is provided on the surface of the base material layer 74, the base material layer 74 and the transparent conductive layer 71 may be in contact with each other (for example, the first described later). The touch sensor layer manufactured by the method), the base material layer 74 and the transparent conductive layer 71 may not be in contact with each other (for example, the touch sensor layer manufactured by the second method described later). The touch sensor layer 70 may include an adhesive layer, a separation layer, a protective layer, and the like in addition to the base material layer 74 and the transparent conductive layer 71.
Examples of the adhesive layer include an adhesive layer and an adhesive layer. The thickness of the touch sensor layer 70 can be 1 μm to 100 μm, 5 μm to 50 μm, and 10 μm to 30 μm. Within such a range, it is easy to achieve both bending resistance and impact resistance of the optical laminate.

An example of the capacitance type touch sensor layer is composed of a base material layer, a transparent conductive layer for position detection provided on the surface of the base material layer, and a touch position detection circuit. In a display device provided with an optical laminate having a capacitance type touch sensor layer, when the surface of the front plate 10 is touched, the transparent conductive layer is grounded via the capacitance of the human body at the touched point. Will be done. The touch position detection circuit detects the grounding of the transparent conductive layer, and the touched position is detected. By having a plurality of transparent conductive layers separated from each other, more detailed position detection becomes possible.

The transparent conductive layer may be a transparent conductive layer made of a metal oxide such as ITO, or may be a metal layer made of a metal such as aluminum, copper, silver, gold, or an alloy thereof.

The separation layer can be a layer formed on a substrate such as glass and for separating the transparent conductive layer formed on the separation layer from the substrate together with the separation layer. The separation layer is preferably an inorganic layer or an organic layer. Examples of the material forming the inorganic layer include silicon oxide. As the material for forming the organic material layer, for example, a (meth) acrylic resin composition, an epoxy resin composition, a polyimide resin composition, or the like can be used.

The touch sensor layer 70 may include a protective layer that is in contact with the transparent conductive layer 71 and protects the conductive layer. The protective layer contains at least one of an organic insulating film and an inorganic insulating film, and these films can be formed by a spin coating method, a sputtering method, a vapor deposition method or the like.

The touch sensor layer 70 can be manufactured, for example, as follows. In the first method, the base material layer 74 is first laminated on the glass substrate via the adhesive layer. A transparent conductive layer 71 patterned by photolithography is formed on the base material layer 74. By applying heat, the glass substrate and the base material layer 74 are separated to obtain a touch sensor layer 70 composed of the transparent conductive layer 71 and the base material layer 74.

In the second method, a separation layer is first formed on the glass substrate, and if necessary, a protective layer is formed on the separation layer. A transparent conductive layer 71 patterned by photolithography is formed on the separation layer (or protective layer). A peelable protective film is laminated on the transparent conductive layer 71, and the transparent conductive layer 71 to the separation layer are transferred to separate the glass substrate. A touch having the transparent conductive layer 71, the separation layer, the adhesive layer, and the base material layer 74 in this order by adhering the base material layer 74 and the separation layer via the adhesive layer and peeling off the peelable protective film. The sensor layer 70 is obtained. The laminated body composed of the transparent conductive layer 71 and the separation layer may be used as the touch sensor layer 70 without being bonded to the base material layer 74.

Examples of the base material layer 74 of the touch sensor layer include resin films such as triacetyl cellulose, polyethylene terephthalate, polyethylene naphthalate, polyolefin, polycycloolefin, polycarbonate, polyether sulfone, polyarylate, polyimide, polyamide, and polystyrene. Polyethylene terephthalate is preferably used from the viewpoint of easily forming a base material layer having a desired toughness.

The base material layer 74 of the touch sensor layer preferably has a thickness of 50 μm or less, and more preferably 30 μm or less, from the viewpoint of easily forming an optical laminate having excellent bending resistance. The base material layer 74 of the touch sensor layer has a thickness of, for example, 5 μm or more.

[Manufacturing method of optical laminate]
The optical laminate of the present invention is manufactured by bonding a front plate, a protective film, a polarizing layer, and a touch sensor layer using an adhesive layer. As a method of binding the respective layers, an adhesive layer may be formed on the bonding surface of one layer and then the other layer may be laminated, or an adhesive layer may be formed on the bonding surface of both layers. After that, the adhesive layers may be combined.
The method of forming the pressure-sensitive adhesive layer on the surface to which the layers are bonded may be formed by using the pressure-sensitive adhesive composition as described above, or a sheet-like pressure-sensitive adhesive that can be handled independently is prepared and used. It may be formed by sticking it on the surface.

The optical laminate can be arranged on the display surface of the display panel, for example, to form a display device. Optical laminates are particularly preferred for applications where they are applied to the display surface of flexible display panels. The display device including the optical laminate of the present invention has excellent impact resistance.

[Display device]
FIG. 4 is a cross-sectional view showing an example of the structure of the display device of the present invention. The display device 200 has an optical laminate 100 arranged on the front surface (visual side) thereof and a display panel 80. The optical laminate 100 and the display panel 80 are generally bonded using an adhesive layer or an adhesive layer (non-display). The display panel may be configured to be foldable with the viewing side surface on the inside, or may be configured to be foldable with the viewing side surface on the outside, and may be configured to be foldable. It may be the one. Specific examples of the display panel include a liquid crystal display element, an organic EL display element, an inorganic EL display element, a plasma display element, and a field emission type display element.

The display device 200 can be used as a mobile device such as a smartphone or tablet, a television, a digital photo frame, an electronic signage, a measuring instrument or an instrument, an office device, a medical device, a computer device, or the like.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In this example, the unit "part" of the ratio of blending substances is based on weight unless otherwise specified.

<Manufacturing example 1>
Preparation of Front Plate A polyamide-imide (PAI) film having a thickness of 50 μm was prepared in the same manner as in Example 4 of JP-A-2018-119141.

30 parts of polyfunctional acrylate (MIWON Specialty Chemicals "MIRAMER M340" (trade name)), 50 parts of nanosilica sol (average particle size 12 nm, solid content 40%) dispersed in propylene glycol monomethyl ether, 17 parts of ethyl acetate, 2.7 parts of photopolymerization initiator (CIBA "Irgacure 184" (trade name)), 0.3 parts of fluorine-based additive ("KY-1203" (trade name) manufactured by Shin-Etsu Chemical Industry Co., Ltd.), A composition for a hard coat layer was produced by mixing using a stirrer and filtering using a filter made of polypropylene (PP) material.

The composition for a hard coat layer was applied to one surface of the PAI film, the solvent was dried, and UV curing was performed to prepare a front plate having a hard coat layer on one side of the PAI film. The obtained front plate had a thickness of 60 μm and a tensile elastic modulus of 6 GPa.

<Manufacturing example 2>
Preparation of Circular Polarizing Plate A polyvinyl alcohol (PVA) film having an average degree of polymerization of about 2,400, a saponification degree of 99.9 mol% or more, and a thickness of 20 μm was prepared. The PVA film was immersed in pure water at 30 ° C. and then immersed in an aqueous solution having an iodine / potassium iodide / water mass ratio of 0.02 / 2/100 at 30 ° C. for iodine staining (iodine staining). Process). The PVA film that had undergone the iodine dyeing step was immersed in an aqueous solution having a mass ratio of potassium iodide / boric acid / water of 12/5/100 at 56.5 ° C. to perform boric acid treatment (boric acid treatment step). ). The PVA film that had undergone the boric acid treatment step was washed with pure water at 8 ° C. and then dried at 65 ° C. to obtain a polarizer in which iodine was adsorbed and oriented on polyvinyl alcohol. The PVA film was stretched in the iodine dyeing step and the boric acid treatment step. The total draw ratio of the PVA film was 5.3 times. The thickness of the obtained polarizer was 7 μm.

The obtained polarizer and a cycloolefin polymer (COP) film having a thickness of 13 μm (“ZF-14” (trade name) manufactured by Nippon Zeon Corporation), an in-plane retardation value at a wavelength of 550 nm is 1 nm) are water-based. It was bonded with a nip roll via an adhesive. While maintaining the tension per unit width of the obtained laminate at 430 N / m, it was dried at 60 ° C. for 2 minutes to obtain a linear polarizing plate having a COP film on one side. As water-based adhesives, 100 parts of water, 3 parts of carboxyl group-modified polyvinyl alcohol ("Kuraray Poval KL318" (trade name) manufactured by Kuraray Co., Ltd.) and water-soluble polyamide epoxy resin (Taoka Chemical Industry Co., Ltd.) The product to which 1.5 parts of "Smiley's Resin 650" (trade name, aqueous solution having a solid content concentration of 30%) was added was used.

As the 1/2 wave plate, a film composed of a layer in which a liquid crystal compound was cured and an alignment film was used.
The thickness of the 1/2 wave plate was 2 μm. As the 1/4 wave plate, a film composed of a layer in which a liquid crystal compound was cured and an alignment film was used. The thickness of the 1/4 wave plate was 1 μm.

The 1/2 wavelength plate and the 1/4 wavelength plate were bonded together using an ultraviolet curable adhesive. A laminated body of a 1/2 wave plate and a 1/4 wave plate was bonded to a linear polarizing plate via a (meth) acrylic pressure-sensitive adhesive having a thickness of 5 μm to obtain a circularly polarizing plate. The thickness of the circularly polarizing plate was 30 μm.

<Manufacturing example 3>
Manufacture of Adhesive and Preparation of Adhesive Layer [Adhesive Layer A1]
25 parts of 4-hydroxybutyl acrylate (4-HBA), 2-ethylhexyl acrylate (2-EHA) 50 in a 500 ml 4-neck reactor equipped with a cooling device so that nitrogen gas is refluxed and temperature control is easy. After adding 15 parts of methyl acrylate (MA) and 10 parts of isobornyl acrylate (IBOA), 100 parts of ethyl acetate (EAc) was added as a solvent. Nitrogen gas was purged for 1 hour to remove oxygen and the temperature of the mixture was maintained at 60 ° C. When the mixture became uniform, 0.07 part of the reaction initiator azobisisobutyronitrile (AIBN) was added to 100 parts of the mixture. The reaction was carried out for about 5 hours to produce an acrylic copolymer 1 having a weight average molecular weight of about 800,000.

100 parts by mass of the acrylic copolymer 1 and 0.5 parts by mass of a cross-linking agent (“CORONATE-L” (trade name) manufactured by Tosoh Corporation) were mixed to obtain a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition was applied onto a release film coated with a silicon release agent and dried at 100 ° C. for 1 minute to obtain a pressure-sensitive adhesive layer A1. The pressure-sensitive adhesive layer A1 had a storage elastic modulus (G') of 0.3 MPa. In the examples described later, the thickness of the pressure-sensitive adhesive layer was adjusted by adjusting the coating thickness of the pressure-sensitive adhesive composition.

[Adhesive layer A2]
Acrylic copolymer 2 was produced in the same manner as acrylic copolymer 1 except that butyl acrylate (BA) was used instead of methyl acrylate (MA). Further, the pressure-sensitive adhesive layer A2 was obtained in the same manner as the pressure-sensitive adhesive layer A1. The pressure-sensitive adhesive layer A2 had a storage elastic modulus (G') of 0.08 MPa.

[Adhesive layer A3]
The acrylic copolymer 3 was produced in the same manner as the acrylic copolymer 1 except that hexyl acrylate (HA) was used instead of the methyl acrylate (MA). Further, the pressure-sensitive adhesive layer A3 was obtained in the same manner as the pressure-sensitive adhesive layer A1. The pressure-sensitive adhesive layer A3 had a storage elastic modulus (G') of 0.02 MPa.

<Manufacturing example 3>
Fabrication of optical laminate [preparation of protective film]
As a protective film, a polyethylene terephthalate (PET) film having a thickness of 80 μm (“SH82” (trade name) manufactured by SKC) was prepared. The tensile elastic modulus of this PET film was 5 GPa in the mechanical axis direction and 2 GPa in the width direction.

[Preparation of touch sensor panel]
A touch sensor panel was prepared in which a transparent conductive layer which is ITO, a separation layer which is an acrylic resin, an adhesive layer, and a base material layer which is a COP film are laminated in this order from the visual side. The total thickness of the transparent conductive layer, the separation layer and the adhesive layer was 7 μm. The thickness of the base material layer was 13 μm.

[Preparation of optical laminate]
Corona treatment was applied to the PAI film side surface of the front plate, the front and back surfaces of the protective film, the front and back surfaces of the circularly polarizing plate, and the transparent conductive layer side surface of the touch sensor panel. The corona treatment was performed under the conditions of frequency: 20 kHz / voltage: 8.6 kV / power: 2.5 kW / speed: 6 m / min. With reference to FIG. 1, from the side to be visually recognized, the front plate 10, the third adhesive layer 20, the protective film 30, the second adhesive layer 40, the polarizing layer 50, the first adhesive layer 60, and the touch sensor layer. Each layer was laminated in the order of 70, bonded using a roll joining machine, and cured by an autoclave to obtain an optical laminate.

<Measuring method of layer thickness>
The thickness of each layer was measured using a contact-type film thickness measuring device (“MS-5C” (trade name) manufactured by Nikon Corporation). However, the polarizer and the alignment film were measured using a laser microscope (“OLS3000” (trade name) manufactured by Olympus Corporation).

<Storage modulus (G')>
Samples were prepared by stacking the pressure-sensitive adhesive layers to a size of 150 μm. The storage elastic modulus (G') was measured using a rheometer (“MCR-301” (trade name) manufactured by Antonio Parr). The measurement conditions were a temperature of 25 ° C., a stress of 1%, and a frequency of 1 Hz.

<Tension modulus>
A rectangular small piece having a long side of 110 mm and a short side of 10 mm was cut out from the member using a super cutter. Next, use the upper and lower grips of a tensile tester (autograph "AG-Xplus" (trade name) manufactured by Shimadzu Corporation) to sandwich both ends of the measurement sample in the long side direction so that the distance between the grips is 5 cm, and set the temperature. In an environment of 23 ° C. and 55% relative humidity, the measurement sample is pulled in the length direction of the measurement sample at a tensile speed of 4 mm / min, and the temperature 23 is determined from the slope of a straight line between 20 and 40 MPa in the obtained stress-strain curve. The tensile elastic modulus (MPa) at ° C. and a relative humidity of 55% was calculated. At this time, as the thickness for calculating the stress, the thickness value of the layer measured as described above was used.

<Performance evaluation of optical laminate>
[Impact resistance test]
A rectangular piece having a long side of 150 mm and a short side of 70 mm was cut out from the optical laminate using a super cutter. An adhesive layer was provided on the touch sensor layer side of the small piece and bonded to an acrylic plate. Then, the small piece is placed in an environment of 23 ° C. and 55% relative humidity, and the evaluation pen is held so that the pen tip is located at a height of 10 cm from the outermost surface of the front plate of the small piece and the pen tip faces downward. , The evaluation pen was dropped from that position.

The front plate of the small piece was marked at the position of the bridge in the pattern of the transparent conductive layer of the touch sensor layer, and the evaluation pen was dropped so that the pen tip touched the mark. As the evaluation pen, a pen having a mass of 5.6 g and a pen tip diameter of 0.75 mm was used. The small pieces after the evaluation pen was dropped were visually observed and the touch sensor layer function was confirmed, and the evaluation was performed according to the following criteria.

◎ (excellent): No cracks. Touch sensor layer function maintenance.
〇 (Good): There is a crack. Touch sensor layer function maintenance.
× (impossible): There is a crack. No touch sensor layer function.

[Calculation of impact resistance index A]
The impact resistance index A was calculated according to the formula (1).

[Inner fold flexibility test]
The flexibility test was performed at a temperature of 25 ° C. The optical laminates obtained in each Example and Comparative Example were installed in a bending tester (“CFT-720C” (trade name) manufactured by Covotech) in a flat state (non-bent state), and the front plate side was inside. The optical laminate was bent 180 ° so that the distance between the facing front plates was 4.0 mm (bending radius 2 mm). After that, it returned to the original flat state. When a series of operations was performed once, the number of times of bending was counted as one, and this bending operation was repeated. The bending speed was 60 rpm. The number of bends when cracks or floating of the adhesive layer occurred in the region bent by the bending operation was recorded as the limit number of bends. The limit bending number was evaluated according to the following criteria.

◎ (excellent): The limit number of bends is 100,000 or more,
〇 (Good): The limit number of bends is 50,000 or more and less than 100,000,
△ (defective): The limit number of bends is 10,000 or more and less than 50,000,
× (impossible): The limit number of bends is less than 10,000,

[Outer fold flexibility test]
The optical laminates obtained in each Example and Comparative Example are installed in a bending tester (“CFT-720C” (trade name) manufactured by Covotech) in a flat state (non-bent state), and the front plate side is on the outside. The limit number of bendings was recorded and evaluated in the same manner as in the inward bending flexibility test except that the bending was performed so as to be.

<Example 1>
The pressure-sensitive adhesive layer A3 (thickness 50 μm, G'= 0.02 MPa) is placed on the third pressure-sensitive adhesive layer 20, and the pressure-sensitive adhesive layer A3 (thickness 50 μm, G'= 0.02 MPa) is placed on the second pressure-sensitive adhesive layer 40. The pressure-sensitive adhesive layer A3 (thickness 50 μm, G'= 0.02 MPa) was used for the first pressure-sensitive adhesive layer 60 to obtain an optical laminate. The impact resistance index A was calculated for the obtained optical laminate, and the impact resistance test and the flexibility test were performed. The results are shown in Table 1.

<Example 2>
The pressure-sensitive adhesive layer A3 (thickness 25 μm, G'= 0.02 MPa) is placed on the third pressure-sensitive adhesive layer 20, and the pressure-sensitive adhesive layer A3 (thickness 25 μm, G'= 0.02 MPa) is placed on the second pressure-sensitive adhesive layer 40. The pressure-sensitive adhesive layer A3 (thickness 50 μm, G'= 0.02 MPa) was used for the first pressure-sensitive adhesive layer 60 to obtain an optical laminate. The impact resistance index A was calculated for the obtained optical laminate, and the impact resistance test and the flexibility test were performed. The results are shown in Table 1.

<Example 3>
The pressure-sensitive adhesive layer A3 (thickness 25 μm, G'= 0.02 MPa) is placed on the third pressure-sensitive adhesive layer 20, and the pressure-sensitive adhesive layer A3 (thickness 25 μm, G'= 0.02 MPa) is placed on the second pressure-sensitive adhesive layer 40. The pressure-sensitive adhesive layer A3 (thickness 25 μm, G'= 0.02 MPa) was used for the first pressure-sensitive adhesive layer 60 to obtain an optical laminate. The impact resistance index A was calculated for the obtained optical laminate, and the impact resistance test and the flexibility test were performed. The results are shown in Table 1.

<Example 4>
The pressure-sensitive adhesive layer A3 (thickness 10 μm, G'= 0.02 MPa) is placed on the third pressure-sensitive adhesive layer 20, and the pressure-sensitive adhesive layer A2 (thickness 25 μm, G'= 0.08 MPa) is placed on the second pressure-sensitive adhesive layer 40. The pressure-sensitive adhesive layer A2 (thickness 25 μm, G'= 0.08 MPa) was used for the first pressure-sensitive adhesive layer 60 to obtain an optical laminate. The impact resistance index A was calculated for the obtained optical laminate, and the impact resistance test and the flexibility test were performed. The results are shown in Table 1.

<Example 5>
The pressure-sensitive adhesive layer A1 (thickness 10 μm, G'= 0.3 MPa) is placed on the third pressure-sensitive adhesive layer 20, and the pressure-sensitive adhesive layer A2 (thickness 25 μm, G'= 0.08 MPa) is placed on the second pressure-sensitive adhesive layer 40. The pressure-sensitive adhesive layer A1 (thickness 50 μm, G'= 0.3 MPa) was used for the first pressure-sensitive adhesive layer 60 to obtain an optical laminate.
The impact resistance index A was calculated for the obtained optical laminate, and the impact resistance test and the flexibility test were performed. The results are shown in Table 1.

<Example 6>
The pressure-sensitive adhesive layer A3 (thickness 10 μm, G'= 0.02 MPa) is placed on the third pressure-sensitive adhesive layer 20, and the pressure-sensitive adhesive layer A1 (thickness 25 μm, G'= 0.3 MPa) is placed on the second pressure-sensitive adhesive layer 40. The pressure-sensitive adhesive layer A1 (thickness 50 μm, G'= 0.3 MPa) was used for the first pressure-sensitive adhesive layer 60 to obtain an optical laminate.
The impact resistance index A was calculated for the obtained optical laminate, and the impact resistance test and the flexibility test were performed. The results are shown in Table 1.

<Comparative example 1>
The pressure-sensitive adhesive layer A1 (thickness 10 μm, G'= 0.3 MPa) is placed on the third pressure-sensitive adhesive layer 20, and the pressure-sensitive adhesive layer A1 (thickness 10 μm, G'= 0.3 MPa) is placed on the second pressure-sensitive adhesive layer 40. The pressure-sensitive adhesive layer A1 (thickness 50 μm, G'= 0.3 MPa) was used for the first pressure-sensitive adhesive layer 60 to obtain an optical laminate. The impact resistance index A was calculated for the obtained optical laminate, and the impact resistance test and the flexibility test were performed. The results are shown in Table 2.

<Comparative example 2>
The pressure-sensitive adhesive layer A1 (thickness 25 μm, G'= 0.3 MPa) is placed on the third pressure-sensitive adhesive layer 20, and the pressure-sensitive adhesive layer A1 (thickness 25 μm, G'= 0.3 MPa) is placed on the second pressure-sensitive adhesive layer 40. The pressure-sensitive adhesive layer A1 (thickness 25 μm, G'= 0.3 MPa) was used for the first pressure-sensitive adhesive layer 60 to obtain an optical laminate. The impact resistance index A was calculated for the obtained optical laminate, and the impact resistance test and the flexibility test were performed. The results are shown in Table 2.

<Comparative example 3>
The pressure-sensitive adhesive layer A1 (thickness 10 μm, G'= 0.3 MPa) is placed on the third pressure-sensitive adhesive layer 20, and the pressure-sensitive adhesive layer A1 (thickness 10 μm, G'= 0.3 MPa) is placed on the second pressure-sensitive adhesive layer 40. The pressure-sensitive adhesive layer A1 (thickness 10 μm, G'= 0.3 MPa) was used for the first pressure-sensitive adhesive layer 60 to obtain an optical laminate. The impact resistance index A was calculated for the obtained optical laminate, and the impact resistance test and the flexibility test were performed. The results are shown in Table 2.

The laminate of the example having an impact resistance index A of 200 or more showed excellent performance in all of the impact resistance test, the inner bending flexibility test and the outer bending flexibility test. On the other hand, the laminated body of the comparative example having an impact resistance index A of less than 200 was inferior in any one of the impact resistance test, the inner bending flexibility test and the outer bending flexibility test.

10 ... Front plate,
20 ... Third adhesive layer,
30 ... Protective film,
40 ... Second adhesive layer,
50 ... Polarizing layer,
51 ... Polarizer,
52 ... Adhesive layer,
53 ... 1/2 wave plate,
54 ... Adhesive layer,
55 ... 1/4 wave plate,
60 ... First adhesive layer,
70 ... Touch sensor layer,
71 ... Transparent conductive layer,
72 ... Separation layer,
73 ... Adhesive layer,
74 ... Base material layer,
80 ... Display panel,
100 ... Optical laminate,
200 ... Display device.

Claims

An optical laminate comprising a front plate, a third pressure-sensitive adhesive layer, a protective film, a second pressure-sensitive adhesive layer, a polarizing layer, a first pressure-sensitive adhesive layer, and a touch sensor layer in this order from the visual side.
Over 200
formula

Wherein, t n denotes the thickness of the n-th of the pressure-sensitive adhesive layer ([mu] m) from the touch sensor layer, G 'n, the storage elastic modulus at a temperature of 25 ° C. for n-th of the pressure-sensitive adhesive layer from the touch sensor layer represents (MPa), a n denotes a value distance ([mu] m) divided by t n from the touch sensor layer top surface to the n-th of the pressure-sensitive adhesive layer lower surface. ]
An optical laminate having an impact resistance index A represented by.
The optical laminate according to claim 1, which has an impact resistance index A of 2000 or more.
The optical laminate according to claim 1 or 2, wherein the first, second and third pressure-sensitive adhesive layers have a thickness of 3 to 100 μm.
The optical laminate according to any one of claims 1 to 3, wherein the storage elastic modulus of the first, second and third pressure-sensitive adhesive layers at a temperature of 25 ° C. is 0.005 to 1.0 MPa.
The optical laminate according to any one of claims 1 to 4, wherein the first, second and third pressure-sensitive adhesive layers include a pressure-sensitive adhesive composition using a (meth) acrylic resin as a base polymer.
The optical laminate according to claim 5, wherein the first, second and third pressure-sensitive adhesive layers further contain a cross-linking agent.
The optical laminate according to any one of claims 1 to 6, which is applied to the display surface of the display panel.
A display device having a display panel and the optical laminate according to any one of claims 1 to 7 applied to the display surface of the display panel.