JP2019144681A - Touch panel device and touch panel - Google Patents

Abstract

To provide a touch panel device suppressed from increase in resistance value when bent.SOLUTION: A touch panel has, on a first flexible base material, a transparent conductive layer, a protective layer, an adhesive layer, and a second flexible base material in this order, wherein the total of thicknesses of the protective layer and adhesive layer is less than 100 μm, the protective film has a drawing elastic modulus of 400-4,000 MPa at a drawing rate of 0.01 mm/second, and a drawing stress of 15-60 MPa when drawn by 2%, and the adhesive layer has a storage elastic modulus of 0.01-0.5 MPa.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a touch panel device and a touch panel.

  In recent years, display devices including a touch panel device have been widely used. A touch panel device provided on a display device may be used by being attached to an optical film such as an antireflection film or a polarizing film, a protective film, a display device, or the like via an adhesive layer.

  In Patent Document 1, in a laminate in which a specific adhesive layer is formed on a specific transparent substrate, the transparent substrate and a specific transparent conductive substrate are stacked via the adhesive layer. A transparent optical member is disclosed.

JP 2013-14132 A

  The present inventors have studied a touch panel device that can be used for a flexible display. Pattern-like transparent conductive layers widely used for touch panel devices are vulnerable to bending, and the conductivity may be reduced due to cracks or the like. Even when an adhesive layer is provided on the transparent conductive layer to fill the concave portion of the patterned transparent conductive layer, the decrease in conductivity due to bending may not be sufficiently suppressed.

  Under such circumstances, further thinning of the flexible display is required. When the thickness of a member such as a transparent substrate is reduced to further reduce the thickness of a touch panel device, the inventors reduce rigidity, and the curvature for bending a flexible display is substantially reduced. It has been found that this is likely to occur, and the conductivity tends to decrease.

  This invention is made | formed in view of such a situation, and it aims at providing the touch panel device by which the raise of the resistance value at the time of bending was suppressed, and the touch panel using the said touch panel device.

One embodiment of the touch panel device according to the present invention has a transparent conductive layer, a protective film, an adhesive layer, and a second flexible substrate in this order on the first flexible substrate. ,
The total thickness of the protective film and the adhesive layer is less than 100 μm,
The protective film has a tensile modulus of 400 MPa to 4000 MPa at a tensile rate of 0.01 mm / second, and a tensile stress of 15 MPa to 60 MPa when stretched by 2%,
The adhesive layer has a storage elastic modulus of 0.01 to 0.5 MPa.

  One embodiment of the touch panel according to the present invention includes the touch panel device.

  ADVANTAGE OF THE INVENTION According to this invention, the touch panel device by which the raise of the resistance value at the time of bending was suppressed and the touch panel using the said touch panel device can be provided.

FIG. 1 is a schematic cross-sectional view showing an embodiment of a touch panel device. FIG. 2 is a schematic cross-sectional view showing another embodiment of the touch panel device. FIG. 3 is a schematic cross-sectional view showing another embodiment of the touch panel device. FIG. 4 is a schematic cross-sectional view showing another embodiment of the touch panel device. FIG. 5 is a schematic cross-sectional view showing an embodiment of the touch panel. FIG. 6 is a schematic cross-sectional view showing another embodiment of the touch panel. FIG. 7 is a schematic plan view for explaining a sample for measuring tensile elastic modulus. FIG. 8 is a schematic (a) plan view and (b) side view for explaining a sample for a flexibility test.

Hereinafter, the touch panel device and the touch panel according to the present embodiment will be described.
In this embodiment, the monomer is an ethylenically unsaturated monomer. Further, (meth) acrylic acid includes each of acrylic acid and methacrylic acid, (meth) acrylate includes each of acrylate and methacrylate, and (meth) acryloyl group includes each of acryloyl group and methacryloyl group. .
In the present embodiment, “transparent” means transparency that does not hinder the visibility of images from a display device of a touch panel including a touch panel device. Therefore, it includes colorless and transparent and colored transparency that does not hinder visibility, is not defined by strict transmittance, and can be appropriately determined according to the use of the touch panel sensor.

[Touch panel device]
The layer configuration of the touch panel device of the present embodiment will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an embodiment of a touch panel device. In the touch panel device 10 in FIG. 1, a transparent conductive layer 2, a protective film 3, an adhesive layer 4, and a second flexible substrate 5 are laminated on a first flexible substrate 1 in this order. ing. The transparent conductive layer 2 may be formed in a desired pattern, and in that case, the protective film 3 may fill the concave portion of the transparent conductive layer 2. In this embodiment, the thickness t of the protective film 3 is a thickness from the upper surface of the transparent conductive layer 2 as shown in FIG. 1 and does not include a portion that fills the concave portion of the transparent conductive layer 2.

In order to specify the operated position, the touch panel device usually includes a first electrode and a second electrode orthogonal to the first electrode. The electrode will be described with reference to FIGS. 2 to 4 are schematic cross-sectional views each showing one embodiment of a touch panel device.
The touch panel device 20 of FIG. 2 has the transparent conductive layer 2, the protective film 3, the adhesion layer 4, and the 2nd flexible base material 5 on the 1st flexible base material 1, On the second flexible base material 5, a second transparent conductive layer 6, a second protective film 7, a second adhesive layer 8, and a third flexible base material 9 are provided. Yes. In the example of the touch panel device 20 of FIG. 2, the operated position can be specified by using the transparent conductive layer 2 and the second transparent conductive layer 6 as the first electrode and the second electrode, respectively. The layer configuration from the first flexible substrate 1 to the second flexible substrate 5 in FIG. 2 is the same layer configuration as the touch panel device 10 in FIG. Also, the layer configuration from the second flexible substrate 5 to the third flexible substrate 9 in FIG. 2 is the same as the touch panel device 10 in FIG.

  3 includes a transparent conductive layer 2, a protective film 3, an adhesive layer 4, and a second flexible substrate 5 on both sides of the first flexible substrate 1, respectively. Have. In the example of the touch panel device 3 in FIG. 3, the operated position can be specified by using the two transparent conductive layers 2 as the first electrode and the second electrode, respectively.

  The touch panel device 40 in FIG. 4 has a transparent conductive layer 2, a protective film 3, an adhesive layer 4, and a second flexible substrate 5 on one surface of the first flexible substrate 1. . In the example of FIG. 4, the transparent conductive layer 2 includes a transparent conductive layer 2 a serving as a first electrode and a transparent conductive layer 2 b serving as a second electrode, and the transparent conductive layer 2 a is connected by a bridging structure 11. The first electrode and the second electrode are three-dimensionally crossed. In the example of FIG. 4, one transparent conductive layer has the functions of the first electrode and the second electrode. Even when the touch panel device has the bridge structure 11 as in the example of FIG. 4, the thickness t of the protective film 3 is the thickness from the upper surface of the transparent conductive layer 2.

The touch panel device of the present embodiment has a transparent conductive layer, a protective film, an adhesive layer, and a second flexible substrate in this order on the first flexible substrate,
The total thickness of the protective film and the adhesive layer is less than 100 μm,
The protective film has a tensile modulus of 400 MPa to 4000 MPa at a tensile rate of 0.01 mm / second, and a tensile stress of 15 MPa to 60 MPa when stretched by 2%,
When the adhesive layer has a storage elastic modulus of 0.01 to 0.5 MPa, cracking of the transparent conductive layer can be suppressed even during bending, and an increase in resistance can be suppressed.

As shown in Comparative Example 2 described later, when the thickness of the pressure-sensitive adhesive layer covering the transparent conductive layer is 100 μm or more, the conductivity of the transparent conductive layer was relatively good even when bent. However, as shown in Comparative Example 1 described later, when the thickness of the pressure-sensitive adhesive layer covering the transparent conductive layer is less than 100 μm, the effect of bending of the transparent conductive layer due to bending becomes significant, and the conductivity may be reduced. It became clear. The thinner the adhesive layer, the smaller the curvature of the transparent conductive layer with respect to the same bending moment, so that the transparent conductive layer after bending tends to crack and the conductivity decreases. The knowledge that it becomes easy was obtained.
As a result of intensive studies based on such knowledge, the present inventors have determined that the first flexible base material on which the transparent conductive layer is formed, and the adhesive layer formed on the second flexible base material, It has a two-layer structure of a protective film provided on the transparent conductive layer and an adhesive layer provided between the protective film and the second flexible base material. Further, as the protective film, a tensile speed of 0.01 mm Using a protective film having a tensile modulus of 400 MPa to 4000 MPa per second and a tensile stress of 15 MPa to 60 MPa when stretched by 2%, the adhesive layer has a storage modulus of 0.01 to 0.5 MPa. By using the adhesive layer in combination, it becomes clear that even when the total thickness of the protective film and the adhesive layer is less than 100 μm, the decrease in the conductivity of the transparent conductive layer after bending is suppressed. It was.
Although there is an unclear part about the action of suppressing cracking of the transparent conductive layer by the above configuration, the tensile elastic modulus of the protective film is 400 MPa to 4000 MPa, and the tensile stress when stretched by 2% is 15 MPa to 60 MPa. By the following, it is estimated that when the touch panel device is bent, the protective film is appropriately deformed, and the deformation of the transparent conductive layer is suppressed by the stress. In addition, the adhesive layer provided on the protective film has a storage elastic modulus of 0.01 to 0.5 MPa, so that the adhesive layer becomes more flexible than the protective film and suppresses the force applied to the transparent conductive layer and the protective film. Presumed to be.
From the above, according to this embodiment, even when the total thickness of the protective film and the adhesive layer is less than 100 μm, the decrease in the conductivity of the transparent conductive layer after bending is suppressed.
Hereinafter, details of each layer constituting the touch panel device will be described.

<Flexible substrate>
In the present embodiment, the flexible substrate constituting the first flexible substrate and the second flexible substrate can be appropriately selected from a sheet-like, film-like or plate-like substrate. . In the present embodiment, the flexible substrate may be a resin film, flexible glass, or other optical film such as an antireflection film, a polarizing film, a retardation film, or a flexible hard coat layer. It may be a flexible display such as a liquid crystal display or an organic electroluminescence (OLED) display.

When a resin film is used as the flexible substrate, the resin film may be made of any material that is transparent to visible light. For example, polyester resins such as polyethylene terephthalate and polyethylene naphthalate; acetate resins , Polyethersulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, (meth) acrylic resin, polystyrene resin, polyvinyl alcohol resin, polyarylate resin, polyphenylene sulfide resin, etc. Among them, polyester resins are preferable, and polyethylene terephthalate (PET) is more preferable.
When the flexible substrate is a resin film or flexible glass, its thickness is not particularly limited, but a substrate having a thickness of 10 μm or more and 2000 μm or less can be suitably used.

<Transparent conductive layer>
In this embodiment, the transparent conductive layer is not particularly limited, and can be appropriately selected from conventionally known ones. Examples of the material of the transparent conductive layer include metal oxides such as indium tin oxide (ITO), zinc oxide (ZnO), tin oxide (SnO ₂ ), fluorine-doped tin oxide (FTO), and antimony-doped tin oxide (ATO). And conductive polymers such as polythiophene and polyaniline. Of these, ITO is preferable from the viewpoint of visible light transmittance.
Although the film thickness of a transparent conductive layer is not specifically limited, From the point which suppresses generation | occurrence | production of a crack and is excellent in electroconductivity, it is preferable that they are 10 nm or more and 150 micrometers or less, and it is more preferable that they are 20 nm or more and 100 micrometers or less.

The formation method of a transparent conductive layer is not specifically limited, After forming into a film by a well-known method, a patterned transparent conductive layer is obtained by patterning as needed.
Examples of the film forming method include vapor deposition, sputtering, ion plating, and chemical vapor deposition. Moreover, you may form a transparent conductive layer by preparing the film for transparent conductive layers, and bonding together on a flexible base material.
Examples of the patterning method include known etching methods such as wet etching and dry etching.

<Protective film>
In this embodiment, the protective film is a film that covers the transparent conductive layer, the tensile elastic modulus at a tensile speed of 0.01 mm / second is 400 MPa or more and 4000 MPa or less, and the tensile stress when stretched by 2% is 15 MPa or more and 60 MPa. It is characterized by the following.
By using the specific protective film having the tensile elastic modulus and the tensile stress, the transparent conductive layer can be prevented from cracking.
The protective film is preferably formed using the protective film composition from the viewpoint of easily filling the concave portions of the patterned transparent conductive layer.

In the present embodiment, the protective film composition can be appropriately selected from those in which the protective film obtained has the tensile elastic force and the tensile stress. In the present embodiment, a curable composition is preferable from the viewpoint of tensile modulus and tensile stress. The curable composition may be a thermosetting composition or a photocurable composition. Furthermore, it is more preferable that the cured protective film contains a resin having a ring structure from the viewpoints of flexibility, transparency, adhesion, and salt water resistance.
Hereinafter, a thermosetting composition and a photocurable composition, which are preferable as the protective film composition, will be described in order.

(1) Thermosetting composition The thermosetting composition suitably used as the protective film composition in the present embodiment contains a resin and a curing agent, and further contains other components as necessary. It ’s good. As the thermosetting composition, in terms of flexibility, transparency, adhesion, and salt water resistance, a resin having a ring structure (A) (hereinafter sometimes simply referred to as “resin (A)”), A composition containing blocked isocyanate (B) as a curing agent is preferred.

  The resin (A) preferably has a ring structure. By having the ring structure, the adhesion to the substrate is improved. The site where the ring structure is located may be any of the main chain of the resin (A), the side chain of the resin (A), or the main chain and side chain of the resin (A).

Examples of the ring structure include an aliphatic hydrocarbon ring and an aromatic ring, which may be a heterocycle containing a hetero atom such as an oxygen atom, a sulfur atom or a nitrogen atom in the carbon chain.
Examples of the cyclic hydrocarbon group include monocyclic rings such as cyclopentane and cyclohexane, and polycyclic aliphatic hydrocarbons such as norbornane, bicyclo [2,2,2] octane, and adamantane. Examples of the aromatic ring include benzene, naphthalene, anthracene and the like. Examples of the heterocyclic ring include furan, thiophene, pyrrole, pyran, pyridine, benzofuran, and indole. In the present embodiment, the ring structure of the resin (A) is preferably an aromatic ring and more preferably a benzene ring from the viewpoints of flexibility, transparency, adhesion, and salt water resistance.

  The resin (A) preferably has a reactive functional group. Here, the reactive functional group of the resin (A) refers to a group having reactivity with the blocked isocyanate (B), and specifically includes a hydroxyl group, a carboxyl group, an amino group, and the like. A carboxyl group is preferred.

Resin (A) should just be able to form the protective film which has the said predetermined | prescribed tensile elasticity modulus and tensile stress after hardening, and can be selected and used from various resin.
Examples of the resin (A) include epoxy resin, phenoxy resin, phenol resin, polycarbonate, benzoguanamine resin, polyester, aromatic polyether ketone, alkyd resin, silicone resin, styrene resin, styrene- (meth) acrylic resin, styrene- Examples thereof include, but are not limited to, a butadiene resin, a styrene-maleic acid resin, a cellulose resin, and a butyral resin. The resin (A) may be used alone or in combination of two or more.

The epoxy resin has two or more epoxy groups in one molecule. Examples of the epoxy resin include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A / epichlorohydrin type epoxy resin, N, N, N′N′-tetraglycidyl. -M-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N-diglycidylaniline, N, N-diglycidyltoluidine and the like.
The epoxy resin is also preferably an acid-modified epoxy resin obtained by acid-modifying the epoxy group. Examples of the acid-modified epoxy resin include a cresol novolac-type acid-modified epoxy resin, a bisphenol A-type acid-modified epoxy resin, a bisphenol F-type acid-modified epoxy resin, and a biphenyl-type acid-modified epoxy resin. Photolithographic patterning utilizing alkali developability is possible. Commercially available acid-modified epoxy resins include, for example, CCR-1291H (Mw 8,000, acid value 80 mgKOH / g, manufactured by Nippon Kayaku Co., Ltd.), ZAR1035 (Mw 13,000, acid value 98 mg / g, manufactured by Nippon Kayaku Co., Ltd.) ), ZFR-1491H (Mw 12,000, acid value 98 mg KOH / g, manufactured by Nippon Kayaku Co., Ltd.), ZCR-1798H (Mw 6,500, acid value 60 mg KOH / g, manufactured by Nippon Kayaku Co., Ltd.), UXE-3024 (Mw 10, 000, acid value 60 mgKOH / g, manufactured by Nippon Kayaku Co., Ltd.).

The phenoxy resin is a polyhydroxy polyether having a bisphenol skeleton obtained by reacting an aromatic diol (such as bisphenol A or bisphenol F) with epichlorohydrin.
A commercially available product may be used as the phenoxy resin. For example, JER1256 (number average molecular weight (hereinafter referred to as Mn) 10,000, hydroxyl value 190 mgKOH / g, glass transition temperature (hereinafter referred to as Tg) 95 ° C., manufactured by Mitsubishi Chemical), JER4250 (Mn 9,000, hydroxyl value 180 mgKOH / g) g, Tg 70 ° C., manufactured by Mitsubishi Chemical Corporation), JER4275 (Mn 8,000, hydroxyl value 170 mgKOH / g, Tg 68 ° C., manufactured by Mitsubishi Chemical Corporation), PKHA (Mn 9,000, hydroxyl value 200 mg KOH / g, Tg 81 ° C., manufactured by Gabriel Phenoxies) ), PKHB (Mn 9,500, hydroxyl value 203 mg KOH / g, Tg 84 ° C., manufactured by Gabriel Phenoxies), PKHC (Mn 11,000, hydroxyl value 201 mg KOH / g, Tg 89 ° C., manufactured by Gabriel Phenoxes), PK J (Mn 16,000, hydroxyl value 200 mgKOH / g, Tg 98 ° C., manufactured by Gabriel Phenoxies), PKHH (Mn 13,000, hydroxyl value 201 mg KOH / g, Tg 98 ° C., Gabriel Phenoxys), PKFE (Mn 16,000, Tg 98 ° C., Gabrx) PKCP-80 (Tg 30 ° C., manufactured by Gabriel Phenoxies), YP-50 (Mn 14,000, Tg 84 ° C., manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), YP-55U (hydroxyl value 198 mgKOH / g, Tg 83 ° C., Nippon Steel & Sumikin Chemical Co., Ltd.) YP-50S (hydroxyl value 284 mgKOH / g, Tg 84 ° C., manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), YP-70 (hydroxyl value 270 mgKOH / g, Tg 72 ° C., manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), FX- 93 (weight average molecular weight (hereinafter referred to as Mw) 45,000, hydroxyl value 163 mg KOH / g, Tg 158 ° C., manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), FX-280S (Mw 42,000, hydroxyl value 330 mg KOH / g, Tg 158 ° C., Nippon Steel & Sumikin Chemical) And FX-310 (Mw 45,000, Tg 110 ° C., manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.).

  The polyester can be synthesized by a known synthesis method such as a reaction between a polybasic acid and a polyol, or a transesterification reaction between a polybasic acid ester and a polyol. In order to synthesize a polyester having an aromatic ring, it is preferable to use, for example, an aromatic dicarboxylic acid as the polybasic acid. Furthermore, the polybasic acid is not used alone, and for example, a linear aliphatic dicarboxylic acid, a cyclic aliphatic carboxylic acid, a tri- or higher functional carboxylic acid, and the like can be used at the same time. The polybasic acid includes an acid anhydride group-containing compound.

Examples of the aromatic dicarboxylic acid include, but are not limited to, terephthalic acid and isophthalic acid. Examples of the linear aliphatic dicarboxylic acid include, but are not limited to, adipic acid, sebacic acid, and azelaic acid. Examples of the cycloaliphatic dicarboxylic acid include 1,4-cyclohexanedicarboxylic acid, dicarboxyhydrogenated bisphenol A, dimer acid, 4-methylhexahydrophthalic anhydride, and 3-methylhexahydrophthalic anhydride. However, it is not limited to these. Examples of the tri- or higher functional carboxylic acid include, but are not limited to, trimellitic anhydride and pyromellitic anhydride. Other carboxylic acids include, but are not limited to, unsaturated dicarboxylic acids such as fumaric acid, sulfonic acid metal salt-containing dicarboxylic acids such as sodium 5-sulfoisophthalate, and the like.
Polybasic acids can be used alone or in combination of two or more.
The polyol is preferably a diol and a compound having 3 or more hydroxyl groups.
Examples of the diol include, but are not limited to, ethylene glycol, propylene glycol, 1,4-butanediol, and neopentyl glycol.
Examples of the compound having three or more hydroxyl groups include, but are not limited to, tolmethylolpropane, glycerin, and pentaerythritol. The polyol can be used alone or in combination of two or more.

  A commercially available product may be used as the polyester. For example, Elitel UE3250 (Mn 18,000, hydroxyl value 5 mgKOH / g, Tg40 ° C., manufactured by Unitika), Elitel UE3223G (Mn20,000, hydroxyl value 5 mgKOH / g, Tg-1 ° C, manufactured by Unitika), Elitel UE3201 (Mn20, 000, hydroxyl value 3 mg KOH / g, Tg 65 ° C., manufactured by Unitika), Elitel UE3600 (Mn 20,000, hydroxyl value 4 mgKOH / g, Tg7 ° C., manufactured by Unitika), Elitel XA-0611 (Mn 17,000, hydroxyl value 4 mgKOH / g, Tg65 ° C., manufactured by Unitika Ltd.), Elitel UE3200G (Mn 15,000, hydroxyl value 6 mgKOH / g, Tg65 ° C, produced by Unitika Ltd.), Elitel UE3980 (Mn8,000, hydroxyl value 17 mgKOH / g, Tg63 ° C., Nichika), Elitel XP-0544 (Mn 3,500, hydroxyl value 32 mg KOH / g, Tg 51 ° C., Unitika), Byron 300 (Mn 23,000, hydroxyl value 5 mg KOH / g, Tg 7 ° C., Toyobo), Byron 630 (Mn 23,000, hydroxyl value 5 mg KOH / g, Tg 7 ° C., manufactured by Toyobo), Byron 220 (Mn 3,000, hydroxyl value 50 mg KOH / g, Tg 53 ° C., manufactured by Toyobo), Byron 802 (Mn 3,000, hydroxyl value) 37 mg KOH / g, Tg 60 ° C., manufactured by Toyobo Co., Ltd.), Byron GK810 (Mn 6,000, hydroxyl value 19 mg KOH / g, Tg 46 ° C., manufactured by Toyobo Co., Ltd.), Byron GK 780 (Mn 11,000, hydroxyl value 11 mg KOH / g, Tg 36 ° C., Toyobo Co., Ltd.) Byron), Byron GK250 (Mn10, 00, a hydroxyl value 11mgKOH / g, Tg60 ℃, and the like is manufactured by Toyobo Co., Ltd.), and the like.

  The styrene-maleic acid resin is a resin having an acid value and (meth) acryloyl group obtained by reacting 2-hydroxyethyl acrylate (HEA) or 2-hydroxyethyl methacrylate (HEMA) with an acid anhydride group. It is.

As the cellulose resin, for example, cellulose acetate butyrate (CAB) resin, cellulose acetate propionate (CAP) and the like are preferable.
The CAB resin has a heterocyclic pyran ring as a ring structure. Examples of commercially available products include CAB-551-0.01 (Mn 16,000, hydroxyl value 50 mgKOH / g, Tg 85 ° C., manufactured by Eastman Chemical Co.), CAB-551-0.2 (Mn 30,000, hydroxyl value 53 mgKOH). / G, Tg 101 ° C., manufactured by Eastman Chemical Co.), CAB-553-0.4 (Mn 20,000, hydroxyl value 158 mgKOH / g, Tg 136 ° C., manufactured by Eastman Chemical Co.), CAB-531-1 (Mn 40,000) , Hydroxyl value 56 mgKOH / g, Tg 115 ° C., manufactured by Eastman Chemical Co.), CAB-500-5 (Mn 57,000, hydroxyl value 33 mgKOH / g, Tg 96 ° C., manufactured by Eastman Chemical Co.), Solus 2100 (Mn 6,000, hydroxyl group) 50 mg KOH / g, Tg 75 ° C, Eastman Chemi Manufactured by Le Co.), and the like.

The CAP resin has a heterocyclic pyran ring as a ring structure.
Examples of commercially available CAP resins include CAP-482-0.5 (Mn 25,000, hydroxyl value 86 mg KOH / g, Tg 142 ° C., manufactured by Eastman Chemical Co., Ltd.).

The butyral resin is also called polyvinyl butyral, and is a resin obtained by acetalizing (butyral) polyvinyl alcohol with butyl alcohol. The butyral resin has a heterocyclic butyral ring as a ring structure.
Speaking of commercial products, butyral resin is BL-10 (Mn 15,000, hydroxyl value 247 mg KOH / g, Tg 59 ° C., manufactured by Sekisui Chemical Co., Ltd.), BX-L (Mn 20,000, hydroxyl value 353 mg KOH / g, Tg 74 ° C., Sekisui Chemical Co., Ltd.).

  From the viewpoint of flexibility, the resin (A) is preferably polyester or phenoxy resin.

  The resin (A) preferably has an acid value or a hydroxyl value. When the resin (A) has a hydroxyl value, a hydroxyl value of 2 to 300 mgKOH / g is preferred. When a polyester is used, the hydroxyl value of 2 to 200 mgKOH / g is preferred, and 2 to 100 mgKOH / g is more preferred. When polyester is used for the resin (A), the light transmittance, transparency, flexibility and flexibility of the protective film are further improved, and the adhesion between the protective film and a layer such as a substrate is further improved.

  When a phenoxy resin having a hydroxyl value is used as the resin (A), the hydroxyl value is preferably 50 to 300 mgKOH / g, more preferably 150 to 250 mgKOH / g. When a phenoxy resin is used for the resin (A), the light transmittance and transparency of the protective film are further improved, and the adhesion between the protective film and a layer such as a substrate is further improved. And flexibility are particularly improved. Further, when a phenoxy resin is used, since the refractive index is relatively high, for example, “bone appearance phenomenon: ITO pattern circuit appearance”, which is a problem in JP-A-7-240899, that is, the visibility of the liquid crystal display screen is lowered. The problem of doing can be solved.

  The glass transition temperature (Tg) of the resin (A) is preferably from -30 to 170 ° C, more preferably from 30 to 160 ° C. When Tg is −30 ° C. or higher, the cohesive force is further improved. Moreover, when it becomes 170 degrees C or less, adhesiveness and a flexibility will improve more. Tg is a numerical value measured with a DSC (Differential Scanning Calorimeter) measuring device “DSC-220C” (manufactured by Seiko Instruments Inc.).

  The resin (A) preferably has a number average molecular weight of 1,000 to 30,000, more preferably 2,000 to 20,000. If the number average molecular weight is 1,000 or more, the flexibility of the protective film is increased, so that the flexibility and adhesion to the substrate are further improved. Moreover, if a number average molecular weight is 30,000 or less, the coating strength of a protective film will become high and saltwater tolerance will improve. In this embodiment, the number average molecular weight and the weight average molecular weight are numerical values in terms of polystyrene measured by GPC (gel permeation chromatography).

  The resin (A) preferably has a weight average molecular weight of 5,000 to 80,000, more preferably 10,000 to 70,000. The resin (A) preferably satisfies at least one of the number average molecular weight range and the weight average molecular weight range.

(Block isocyanate (B))
In this embodiment, the blocked isocyanate (B) is a curing agent in which the blocking agent is dissociated (disengaged) by heating, and the generated isocyanate group reacts with the reactive functional group of the resin (A). The dissociation temperature of the blocked isocyanate is a temperature at which the blocking agent is removed, and is preferably 80 to 180 ° C, more preferably 90 to 150 ° C.
When the dissociation temperature is 80 ° C. or higher, the storage stability of the resin composition is improved and the adhesion is further improved. Further, when the dissociation temperature is 180 ° C. or lower, the dimensional stability of the wiring board is further improved.

The blocked isocyanate is composed of a base isocyanate and a blocking agent. The base isocyanate is preferably an isocyanate obtained by blocking a compound such as aromatic polyisocyanate, aliphatic polyisocyanate, and alicyclic polyisocyanate.
Examples of aromatic polyisocyanates include trimethylolpropane adducts of tolylene diisocyanate, isocyanurates of tolylene diisocyanate, oligomers of 4,4′-diphenylmethane diisocyanate, and the like.
Aliphatic polyisocyanates include, for example, hexamethylene diisocyanate biuret, hexamethylene diisocyanate isocyanurate, hexamethylene diisocyanate trimethylolpropane adduct, hexamethylene diisocyanate oligomer, hexamethylene diisocyanate uretdione, tolylene diisocyanate and Examples thereof include isocyanurate bodies of copolymers made of hexamethylene diisocyanate.
Examples of the alicyclic polyisocyanate include an isocyanurate of isophorone diisocyanate, an oligomer of isophorone diisocyanate, and the like.

  Examples of the blocking agent include methyl ethyl ketone oxime (MEKO, dissociation temperature 150 ° C.), dimethylpyrazole (DMP, dissociation temperature 110 ° C.), diethyl malonate (DEM, dissociation temperature 110 ° C.), ε-caprolactam (E-CAP, dissociation temperature). 170 ° C.), butanone oxime (dissociation temperature 160 ° C.), phenol (dissociation temperature 170 ° C.), active methylene compound (dissociation temperature 90 ° C.) and the like are preferable. More preferred are methyl ethyl ketone oxime (MEKO, dissociation temperature 150 ° C.), dimethylpyrazole (DMP, dissociation temperature 110 ° C.), diethyl malonate (DEM, dissociation temperature 110 ° C.) and active methylene compounds (dissociation temperature 90 ° C.). Note that the dissociation temperature may slightly vary depending on the type of isocyanate.

  Commercial products may be used as the blocked isocyanate. For example, Sumidur BL3175 (manufactured by Sumika Covestrourethane), Death Module BL1100 / 1 (manufactured by Sumika Covestrourethane), Death Module PL350 (manufactured by Sumika Covestrourethane), Duranate MF-K60B (Asahi Kasei Chemicals) SBN-70D (Asahi Kasei Chemicals), MF-B60B (Asahi Kasei Chemicals), MF-B90B (Asahi Kasei Chemicals), 17B-60P (Asahi Kasei Chemicals), TPA-B80B (Asahi Kasei Chemicals) Made by Asahi Kasei Chemicals), E402-B80B (made by Asahi Kasei Chemicals), BI-7950 (made by Baxenden), BI-7951 (made by Baxenden), BI-7960 (made by Baxenden) , BI-7961 (Baxe den), BI-7963 (manufactured by Baxenden), BI-7982 (manufactured by Baxenden), BI-7991 (manufactured by Baxenden), BI-7992 (manufactured by Baxenden), Karenz MOI-BM (manufactured by Showa Denko KK) ), Karenz MOI-BP (manufactured by Showa Denko KK) and the like, but are not limited thereto.

  The blocked isocyanate can be used alone or in combination of two or more. In the present embodiment, when two or more kinds of blocked isocyanate are used in combination, the adhesion and the like are further improved.

  It is preferable that 1-20 mass parts is used with respect to 100 mass parts of resin (A), and, as for blocked isocyanate (B), 2-15 mass parts is more preferable. When the blocked isocyanate is used within the above range, the adhesion to the substrate and the salt water resistance are further improved.

  In the present embodiment, the protective film composition may further contain a known catalyst or curing accelerator that accelerates the curing reaction. The said catalyst and hardening accelerator can be used individually or in combination of 2 or more types. When using a hardening accelerator, it is preferable to use 0.01-5 mass parts normally with respect to 100 mass parts of resin (A).

(2) Photocurable composition The photocurable composition used as the protective film composition in the present embodiment contains a photopolymerization initiator and a photocurable compound, and may further contain a resin. Preferably, it may further contain other components as necessary. As the photocurable composition, a resin (A ′) having a ring structure (hereinafter sometimes simply referred to as “resin (A ′)”) in terms of flexibility, transparency, adhesion, and salt water resistance. And a composition containing a photopolymerization initiator and a photocurable compound.

As the resin (A ′) having a ring structure, the same resin (A) as described above can be appropriately selected. Hereinafter, a different point from resin (A) is demonstrated and description here is abbreviate | omitted about the part which is common with resin (A).
The resin (A ′) having a ring structure may have a photopolymerizable functional group instead of the reactive functional group in the resin (A) or together with the reactive functional group. Preferred examples of the photopolymerizable functional group include an ethylenically unsaturated double bond, and specific examples include a (meth) acryloyl group, a vinyl group, and an allyl group.
A photopolymerizable functional group can be introduce | transduced by making the hydroxyl group which the said resin (A) has, and an epoxy (meth) acrylate react, for example. Specific examples include a phenoxy resin having a methacryloyl group obtained by reacting a hydroxyl group of a phenoxy resin with a glycidyl group of glycidyl methacrylate.

  The resin (A ′) preferably has an acid value from the viewpoint of alkali developability. Among them, the acid value of the resin (A ′) is preferably 1 to 200 mgKOH / g, more preferably 2 to 150 mgKOH / g, and further preferably 5 to 100 mgKOH / g. When the acid value is 1 to 200 mgKOH / g, the alkali developability is further improved.

As said photocurable compound, a photoradical curable compound and a photocationic curable compound are preferable.
The photo-radical curable compound is preferably, for example, a monofunctional (meth) acrylic monomer, a polyfunctional (meth) acrylic monomer, other vinyl monomers, or a polyfunctional (meth) acrylic oligomer.

  Examples of the monofunctional (meth) acrylic monomer include alkyl (meth) acrylate and a polar group-containing monofunctional (meth) acrylic monomer. The alkyl (meth) acrylate is a monofunctional (meth) acrylate having an alkyl group. The alkyl group may be linear or branched.

  Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, s-butyl (meth) acrylate, and t-butyl (meth). Acrylate, heptyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, Examples include n-decyl (meth) acrylate.

Examples of the polar group-containing monofunctional (meth) acrylic monomer include a carboxyl group-containing monofunctional (meth) acrylic monomer, a hydroxyl group-containing monofunctional (meth) acrylic monomer, an amide group-containing monofunctional (meth) acrylic monomer, and the like. Examples of the carboxyl group-containing monofunctional (meth) acrylic monomer include acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, and the like.
Examples of the hydroxyl group-containing monofunctional (meth) acrylic monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6 Hydroxyalkyl (meth) acrylates such as hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate; hydroxyethyl (meth) acrylamide, (4-hydroxymethylcyclohexyl) methyl acrylate, N-methylol (meth) acrylamide, N-hydroxy (meth) acrylamide and the like can be mentioned. Examples of the amide group-containing monofunctional (meth) acrylic monomer include N, N-dimethylaminoethyl acrylate, N, N-dimethylacrylamide, N, N-diethylacrylamide, and N-acryloylmorpholine.

Examples of the polyfunctional (meth) acrylic monomer include polyfunctional (meth) acrylates having an acryloyl group or a methacryloyl group. As for the said polyfunctional (meth) acrylate, bifunctional (meth) acrylate and trifunctional or more than (meth) acrylate are mentioned.
Examples of the bifunctional (meth) acrylate include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, hexanediol (meth) acrylate, long chain aliphatic di (meth) acrylate, neopentyl glycol di (meth) acrylate, Hydroxypivalic acid neopentyl glycol di (meth) acrylate, stearic acid modified pentaerythritol di (meth) acrylate, propylene di (meth) acrylate, glycerol (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di ( (Meth) acrylate, tetramethylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, polyester Lenglycol di (meth) acrylate, polypropylene di (meth) acrylate, triglycerol di (meth) acrylate, neopentyl glycol modified trimethylolpropane di (meth) acrylate, allylated cyclohexyl di (meth) acrylate, methoxylated cyclohexyl di ( (Meth) acrylate, acrylated isocyanurate, bis (acryloxyneopentyl glycol) adipate, bisphenol A di (meth) acrylate, tetrabromobisphenol A di (meth) acrylate, bisphenol S di (meth) acrylate, butanediol di (meth) ) Acrylate, phthalic acid di (meth) acrylate, phosphoric acid di (meth) acrylate, zinc di (meth) acrylate, and the like.
The trifunctional or higher functional (meth) acrylates include, for example, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, glycerol tri (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri ( (Meth) acrylate, alkyl-modified dipentaerythritol tri (meth) acrylate, tri (meth) acrylate phosphate, tris (acryloxyethyl) isocyanurate, tris (methacryloxyethyl) isocyanurate, pentaerythritol tetra (meth) acrylate, di Pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetraacrylate, alkyl-modified dipentaerythritol tetra (meth) acrylate, dipen Erythritol monohydroxypenta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, alkyl-modified dipentaerythritol penta (meth) acrylate, carboxylic acid-modified dipentaerythritol penta (meth) acrylate , Urethane tri (meth) acrylate, ester tri (meth) acrylate, urethane hexa (meth) acrylate, ester hexa (meth) acrylate, and the like.
Examples of other vinyl monomers include styrene, vinyl acetate, vinyl chloride, acrylic aldehyde, acrylonitrile, acrylamide, and vinyl caprolactam.

  The polyfunctional (meth) acryl oligomer is preferably a compound having a formula weight or a weight average molecular weight of about 1000 to 20000 and having about 2 to 10 (meth) acryloyl groups. Examples of the polyfunctional (meth) acryl oligomer include urethane (meth) acrylate and epoxy (meth) acrylate.

The photocationic curable compound is preferably a compound having one or more functional groups selected from an oxetane ring, an epoxy ring, a vinyl ether group, and a vinylaryl group in one molecule.
The photocationic curable compound may be an oligomer.
A photocurable compound can be used individually or in combination of 2 or more types.

  The photocurable compound is preferably a compound having a formula weight or Mn of 5000 or less. In addition, when resin (A) has a (meth) acryloyl group, the formula amount or Mn of a photocurable compound is preferably less than 2000.

  The photocurable compound is preferably blended in an amount of 200 to 10,000 parts by mass with respect to 100 parts by mass of the resin (A).

The photopolymerization initiator is preferably a radical photopolymerization initiator or a cationic photopolymerization initiator.
Examples of the radical photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, ethylanthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2- Methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, thioxanthone, diethylthioxanthone, 2-isopropylthio Sandone, 2-chlorothioxanthone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis- (2, 6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and the like.

  In the cationic photopolymerization initiator, for example, the cation moiety is aromatic sulfonium, aromatic iodonium, aromatic diazonium, aromatic ammonium, thianthrhenium, thioxanthonium, (2,4-cyclopentadien-1-yl) [( 1-methylethyl) benzene] -Fe cation, and the anion moiety is BF4-, PF6-, SbF6-, [BX4]-(where X is substituted with at least two fluorine or trifluoromethyl groups) Onium salts composed of a phenyl group).

  As for a photoinitiator, it is preferable to use 1-30 mass parts with respect to 100 mass parts of photocurable compounds, and 2-20 mass parts is more preferable. When the photopolymerization initiator is 1 part by mass or more, the curability is improved and the cohesive force is increased, so that the wet heat property and the solvent resistance are improved. When the photopolymerization initiator is 30 parts by mass or less, an appropriate cured film can be obtained, thereby improving adhesion and flexibility.

  Moreover, the composition for protective films may contain another component in the range which does not impair the effect of this implementation. Examples of other components include antifoaming agents and leveling agents.

  Examples of the antifoaming agent include, but are not limited to, acrylic resins, vinyl ether resins, olefin resins, butadiene resins, modified siloxane resins, dimethylpolysiloxanes, silicones, modified silicones such as fluorine-modified silicones, and petroleum resins. The antifoaming agent can be used alone or in combination of two or more.

  When using an antifoamer, it is preferable that the ratio is 0.1-5 mass parts with respect to 100 mass parts of resin (A), and 0.1-1 mass part is more preferable. When the antifoaming agent is 0.1 parts by weight or more, foaming of the composition is suppressed when mixed, and air bubbles are less likely to remain in the protective film, so that visibility is further improved. Moreover, if it is 5 weight part or less, the transparency of a protective film and the adhesiveness to a base material will improve more.

When the composition for protective films contains a leveling agent, the smoothness of the protective film obtained, transparency, and the adhesiveness to a base material improve more. Examples of the leveling agent include, but are not limited to, acrylic resins, modified silicones, polyether-modified polysiloxane copolymers, dimethylpolysiloxane compounds, silicone-modified copolymers, and organic-modified polysiloxanes.
Leveling agents can be used alone or in combination of two or more.

In order to adjust the viscosity at the time of coating, the composition for protective films may further contain a solvent. A solvent can be suitably selected according to the kind of resin (A), a printing method, etc. Examples of the solvent include ester solvents, ketone solvents, glycol ether solvents, aliphatic solvents, alicyclic solvents, aromatic solvents, alcohol solvents, water, and the like. , Or a combination of two or more.
When using a solvent, it is preferable that the ratio is 5-75 mass% with respect to 100 mass% of whole quantity of the composition for protective films.

The composition for protective films may further contain a colorant as long as the problem of the present embodiment can be solved. The hue according to the hue of a display apparatus can be correct | amended because the composition for protective films contains a coloring agent. Moreover, when a protective film colors, the quality of a protective film can be improved by mix | blending the coloring agent which cancels the said coloring. In particular, the protective film may have a yellow hue. In this case, when a colorant containing at least one selected from the group consisting of red, blue, and purple is blended, the yellow becomes inconspicuous and the quality of the protective film is further improved. improves.
The colorant may be a pigment or a dye. Examples of the pigment include inorganic pigments and organic pigments. Examples of the dye include oil-soluble dyes, acid dyes, direct dyes, basic dyes, mordant dyes, and acid mordant dyes. Of these, pigments are preferable from the viewpoint of heat resistance and the like.

  The method for forming the protective film is not particularly limited. It can form by heating, after apply | coating the composition for protective films on a transparent conductive layer formed on the said 1st flexible base material by a well-known method.

  What is necessary is just to adjust the thickness of a protective film suitably in the range from which the sum total with the thickness of the adhesion layer mentioned later becomes less than 100 micrometers. From the viewpoint of flexibility, the thickness of the protective film is preferably 0.2 μm or more and 50 μm or less, more preferably 0.5 μm or more and 40 μm or less, and further preferably 1 μm or more and 30 μm or less. By setting the thickness of the protective film within the above range, flexibility, adhesion, and transparency are further improved.

<Adhesive layer>
In the present embodiment, the adhesive layer is a layer formed on the protective film and in close contact with the second flexible substrate, and has a storage elastic modulus of 0.01 to 0.5 MPa.
By using the specific adhesive layer having a storage elastic modulus, cracking of the transparent conductive layer can be suppressed.

The adhesive layer contains an acrylic copolymer (C) having a hydroxyl group and a polyisocyanate curing agent (D), and may contain an silane coupling agent (E) and other components. System adhesives.
Hereinafter, the preferable acrylic pressure-sensitive adhesive will be described.

(Acrylic copolymer (C))
The acrylic copolymer (C) has at least a hydroxyl group as a functional group capable of reacting with the polyisocyanate curing agent (D) described later.
The monomer constituting the acrylic copolymer (C) has at least a hydroxyl group-containing monomer, and preferably further has an amide group-containing monomer and an amino group-containing monomer. Preferably, it may have another monomer as required. Each of the monomers can be used alone or in combination of two or more.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxybutyl ( (Meth) acrylate, glycerol mono (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, caprolactone modified ( And (meth) acrylates, vinyl alcohol, allyl alcohol and the like.

  It is preferable that the acrylic copolymer (C) further has an amide group-containing monomer or an amino group-containing monomer. By having an amide group-containing monomer, whitening of the adhesive layer in a high-temperature and high-humidity environment can be suppressed. Moreover, by having an amino group-containing monomer, for example, outgas generated from a polycarbonate-based substrate can be suppressed.

Examples of the amide group-containing monomer include (meth) acrylamide, N-methylolacrylamide, N, N-dimethyl (meth) acrylamide, diacetone (meth) acrylamide, N-vinylacetamide, N-vinylpyrrolidone and the like. It is done.
Examples of amino group-containing monomers include aminomethyl (meth) acrylate, dimethylaminomethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, acrylamide, and N, N-dimethylacrylamide. Etc.

-Other monomer The acrylic copolymer (C) may further contain another monomer. Examples of other monomers include (meth) acrylic acid alkyl esters, alkylene oxide-containing monomers, vinyl monomers, and the like.
The (meth) acrylic acid alkyl ester preferably has 1 to 14 carbon atoms in the alkyl chain. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl ( (Meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl ( Examples include (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, and (meth) acrylic acid cyclic alkyl esters such as cyclohexyl (meth) acrylate.
Examples of the alkylene oxide-containing monomer include methoxypolyethylene glycol (meth) acrylate, ethoxypolyethyleneglycol (meth) acrylate, phenoxypolyethyleneglycol (meth) acrylate, methoxypolypropyleneglycol (meth) acrylate, and the like.
Examples of the vinyl monomer include styrene and vinyl acetate.

  On the other hand, in the present embodiment, it is preferable that the acrylic copolymer (C) does not have a carboxy group-containing monomer from the viewpoint of suppressing corrosion (oxidation) of the transparent conductive layer. Examples of the carboxy group-containing monomer include (meth) acrylic acid, maleic acid, and fumaric acid.

The proportion of the hydroxyl group-containing monomer in the acrylic copolymer (C) is preferably from 0.1 to 40% by mass with respect to 100% by mass of all monomers constituting the acrylic copolymer (C), 0.3-30 mass% is more preferable, and 0.5-20 mass% is further more preferable. Curability improves by making a hydroxyl-containing monomer into 0.1 mass% or more, and it is excellent in adhesiveness by making a hydroxyl-containing monomer into 40 mass% or less.
When the amide group-containing monomer is used, the content ratio is preferably 1 to 50% by mass, and 10 to 40% by mass with respect to 100% by mass of all monomers constituting the acrylic copolymer (C). More preferred. By setting the amide group-containing monomer to 1% by mass or more, whitening of the adhesive layer in a high-temperature and high-humidity environment is suppressed. Also, by setting the amide group-containing monomer to 50% by mass or less, adhesion is achieved. The adhesive strength of the layer is excellent, and the adhesion of the transparent conductive layer and the like is improved.
Moreover, when using an amino group containing monomer, it is preferable that the content rate is 0.1-10 mass% with respect to 100 mass% of all the monomers which comprise an acryl-type copolymer (C). 0.2-5 mass% is more preferable. By setting the amino group-containing monomer to 0.1% by mass or more, it is easy to suppress bubbles generated from the polycarbonate. On the other hand, by setting it as 10 mass% or less, it is suppressed that the adhesion layer yellows.
Moreover, when using the said other monomer, it is preferable that the content rate is 40-98.9 mass% with respect to 100 mass% of all the monomers which comprise an acryl-type copolymer (C). .

In the present embodiment, the weight average molecular weight of the acrylic copolymer (C) is not particularly limited, but is preferably 200,000 to 1,500,000, more preferably 200,000 to 1,000,000 from the viewpoint of the balance of the adhesive performance, and 400,000 to 800,000 is more preferable. As the acrylic copolymer (C), two or more types of copolymers having different weight average molecular weights may be used.
Further, the molecular weight distribution (Mw / Mn) representing the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the acrylic copolymer (C) is preferably 20 or less. By setting the molecular weight distribution to 20 or less, tackiness and peeling resistance are further improved. In addition, a weight average molecular weight and a number average molecular weight are values in terms of polystyrene measured by gel permeation chromatography (GPC).

The glass transition temperature of the acrylic copolymer (C) is not particularly limited, but is preferably −50 ° C. or higher and 0 ° C. or lower, and preferably −40 ° C. or higher and −10 ° C. or lower from the viewpoint of tack and cohesive strength.
The glass transition temperature (Tg) of the acrylic copolymer (C) is described in “Polymer Handbook, Fourth Edition”, J. Mol. Brandrup, E .; H. Immergut, and E.M. A. It is based on Grulke (1999).

  The method for producing the acrylic copolymer (C) is not particularly limited. For example, it can be produced by copolymerizing the above monomers by known solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization or the like. In this implementation, solution polymerization is particularly preferable from the viewpoint of transparency and adhesiveness. The polymerization initiator used for solution polymerization is preferably a peroxide, an azo compound, or the like. Examples of the peroxide include benzoyl peroxide. Examples of the azo compound include azobisisobutyronitrile.

(Polyisocyanate curing agent (D))
In the present embodiment, the polyisocyanate curing agent (D) can be appropriately selected from known polyisocyanate curing agents having two or more isocyanate groups. Specific examples include aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, and alicyclic polyisocyanates. In addition, a polyisocyanate type hardening | curing agent (D) can be used individually by 1 type or in combination of 2 or more types.

  Examples of the aromatic polyisocyanate include 1,3-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2, Examples include 6-tolylene diisocyanate, 4,4′-toluidine diisocyanate, dianisidine diisocyanate, and 4,4′-diphenyl ether diisocyanate.

  Examples of aliphatic polyisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, and dodecamethylene diisocyanate. 2,4,4-trimethylhexamethylene diisocyanate and the like.

  Examples of the araliphatic polyisocyanate include ω, ω′-diisocyanate-1,3-dimethylbenzene, ω, ω′-diisocyanate-1,4-dimethylbenzene, ω, ω′-diisocyanate-1,4-diethylbenzene. 1,4-tetramethylxylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate, xylylene diisocyanate and the like.

  Examples of the alicyclic polyisocyanate include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, and methyl-2. , 4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), 1,4-bis (isocyanatomethyl) cyclohexane and the like.

  Moreover, you may use polyphenylmethane polyisocyanate (PAPI), naphthylene diisocyanate, these polyisocyanate modified products, etc. as a polyisocyanate type hardening | curing agent (D). As the polyisocyanate-modified product, a carbodiimide group, a uretdione group, a uretoimine group, a burette group reacted with water, a group of isocyanurate groups, or a modified product having two or more of these groups can be used. And the reaction product of a polyol and diisocyanate can also be used as a polyisocyanate type hardening | curing agent (D).

  In this embodiment, a modified product of the polyisocyanate may be used as the polyisocyanate curing agent (D). Examples of the modified body include a burette body, an allohanate body, a nurate body, and a trimethylolpropane adduct body of the polyisocyanate.

The burette body refers to a self-condensation product having a burette bond formed by self-condensation of the isocyanate monomer. For example, a burette body of hexamethylene diisocyanate (Sumijour N-75, manufactured by Sumika Bayer Urethane Co., Ltd .; Duranate 24A- 90CX, manufactured by Asahi Kasei).
Body, allophanate body, nurate body, trimethylolpropane adduct body and the like.

  The nurate refers to a trimer of the above-mentioned isocyanate monomer. For example, hexamethylene diisocyanate trimer (Sumijour N-3300, manufactured by Sumika Bayer Urethane Co., Ltd .; Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd .; Aquanate 100, manufactured by Nippon Polyurethane Co., Ltd .; Aquanate 110, manufactured by Nippon Polyurethane Industry Co., Ltd .; Duranate TPA100, manufactured by Asahi Kasei), trimer of isophorone diisocyanate (VESTANAT T-1890, manufactured by Evonik Degussa Japan Co., Ltd .; Death Module Z-4370, Sumika Bayer Urethane Co., Ltd.), tolylene diisocyanate trimer (Coronate 2030, Nippon Polyurethane Co., Ltd.) and the like.

The adduct body is a bifunctional or higher functional isocyanate compound obtained by reacting the above isocyanate monomer with a low molecular active hydrogen-containing compound. For example, as a trifunctional isocyanate compound, trimethylolpropane and hexamethylene diisocyanate are used. Reacted compound (Coronate HL, manufactured by Nippon Polyurethane Co., Ltd .; Sumidur HT, manufactured by Sumika Bayer Urethane Co., Ltd .; Takenate D-160N, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.), compound obtained by reacting trimethylolpropane and tolylene diisocyanate (Coronate L, manufactured by Nippon Polyurethane Co., Ltd .; Sumidur L-75, manufactured by Sumika Bayer Urethane Co., Ltd .; Takenate D-102, manufactured by Mitsui Chemicals Polyurethane Co., Ltd.), a compound obtained by reacting trimethylolpropane with xylylene diisocyanate Product (Takenate D-110N, manufactured by Mitsui Chemicals Polyurethanes Co., Ltd.), a compound obtained by reacting trimethylolpropane and isophorone diisocyanate (Takenate D-140N, manufactured by Mitsui Chemicals Polyurethanes Co., Ltd .; Maitec NY215A, manufactured by Mitsubishi Chemical Co., Ltd.), 2 Examples of the functional isocyanate compound include allohanate compounds (Duranate D-201, manufactured by Asahi Kasei; Coronate 2770, manufactured by Nippon Polyurethane Industry) manufactured from 1,6-hexamethylene diisocyanate and monoalcohol.
Examples of the low molecular active hydrogen-containing compound include bifunctional or higher polyols, polyamines, and polythiols.

In this embodiment, the polyisocyanate-based curing agent (D) is an aromatic fat from the viewpoint of heat resistance under a high temperature environment and from suppressing discoloration of the pressure-sensitive adhesive layer to white when left in a high temperature and high humidity environment. It is preferably a polyisocyanate having a ring structure selected from an aliphatic polyisocyanate, an aliphatic polyisocyanate, an alicyclic polyisocyanate, and a modified polyisocyanate having a ring structure. In this case, the obtained adhesive layer contains a resin having a ring structure.
As the polyisocyanate having a ring structure, a trimethylolpropane adduct of xylylene diisocyanate, a burette of hexamethylene diisocyanate, and a nurate of hexamethylene diisocyanate are preferable.

  In this embodiment, the proportion of the polyisocyanate curing agent (D) is preferably 0.01 to 5 parts by mass, and 0.05 to 3 parts by mass with respect to 100 parts by mass of the acrylic copolymer (C). It is more preferable that it is 0.1-3 mass parts.

(Silane coupling agent (E))
In the present embodiment, the acrylic resin composition for the adhesive layer preferably contains a silane coupling agent. By using a silane coupling agent, the adhesiveness between the pressure-sensitive adhesive layer and the transparent conductive layer is improved, and heat resistance and heat-and-moisture resistance can be improved. Furthermore, the physical properties of heat-and-moisture whitening resistance, gas swellability after being attached to a polycarbonate plate, and step embedding properties can be further improved. When used for this purpose, the proportion of the silane coupling agent (E) is preferably 0.001 to 0.1 parts by mass with respect to 100 parts by mass of the acrylic copolymer (C). It is more preferable that it is 005-5 mass parts.

Specific examples of the silane coupling agent (E) include γ- (meth) acryloxymethyltrimethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, and γ- (meth) acryloxypropyltriethoxy. Alkoxysilane compounds having a (meth) acryloxy group such as silane, γ- (meth) acryloxypropyltributoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropylmethyldiethoxysilane ;
Alkoxysilane compounds having a vinyl group, such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane;
Alkoxysilane compounds such as 5-hexenyltrimethoxysilane, 9-decenyltrimethoxysilane, and styryltrimethoxysilane;
alkoxysilane compounds having an aminoalkyl group such as γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane;
γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane, β-mercaptomethylphenylethyltrimethoxysilane, mercaptomethyltrimethoxysilane, 6 An alkoxysilane compound having a mercapto group, such as mercaptohexyltrimethoxysilane, 10-mercaptodecyltrimethoxysilane;
Tetraalkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane;
3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3 4-epoxycyclohexyl) ethyltriethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, phenyltrimethoxysilane, hexamethylsilazane, diphenyldimethoxysilane, 1,3,5-tris (3-tri Methoxysilylpropyl) isocyanurate, vinyltris (2-methoxyethoxy) silane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane Such as 3-isocyanate propyl triethoxysilane and the like. Among the silane coupling agents, 3-glycidoxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, and the like can be given. A silane coupling agent (E) can be used individually by 1 type or in combination of 2 or more types.

(Other ingredients)
In the present embodiment, the acrylic pressure-sensitive adhesive may further contain other components as long as the effects of the present embodiment are not impaired. Examples of such other components include polyfunctional epoxy compounds and other resins such as acrylic resins, polyester resins, amino resins, epoxy resins, polyurethane resins; coupling agents, tackifiers, talc, calcium carbonate , Fillers such as titanium oxide, colorants, softeners, UV absorbers, antioxidants, antifoaming agents, light stabilizers, weathering stabilizers, curing accelerators, curing retarders, phosphate esters, etc. .

By using the polyfunctional epoxy compound as a curing agent, the heat resistance of the adhesive layer can be further improved. Examples of the polyfunctional epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A / epichlorohydrin type epoxy resin, N, N, N′N ′. -Tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N-diglycidylaniline, N, N-diglycidyltoluidine and the like. A polyfunctional epoxy compound can be used individually by 1 type or in combination of 2 or more types.
When using a polyfunctional epoxy compound, it is preferable that the ratio is 0.1-5 mass parts with respect to 100 mass parts of acrylic copolymers (C).

The formation method of an adhesion layer is not specifically limited. It may be formed by sticking a sheet-like adhesive layer on the protective film, or may be formed by applying a composition for the adhesive layer on the protective film by a known method.
When using the composition for adhesion layers, you may adjust a viscosity by adding a liquid medium as needed for coating. Examples of the liquid medium include hydrocarbon solvents such as toluene, xylene, hexane and heptane; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone and methyl ethyl ketone; halogenated hydrocarbons such as dichloromethane and chloroform Examples of the solvent include ether solvents such as diethyl ether, methoxytoluene, and dioxane, and other hydrocarbon solvents.

  What is necessary is just to adjust the thickness of an adhesion layer suitably in the range from which the sum total with the thickness of the said protective film will be less than 100 micrometers. The thickness of the adhesive layer is preferably 2 μm or more and 95 μm or less, more preferably 5 μm or more and 90 μm or less, further preferably 10 μm or more and 90 μm or less, and particularly preferably 12 μm or more and 85 μm or less from the viewpoint of flexibility. Moreover, it is preferable that the adhesion layer is thicker than the said protective film from the point which prevents the crack of a transparent conductive layer.

<Tensile modulus and tensile stress of protective film>
In this embodiment, the protective film may have a tensile elastic modulus at a tensile rate of 0.01 mm / second of 400 MPa or more and 4000 MPa or less, more preferably 600 MPa or more, and a tensile stress when the protective film is stretched by 2% is 15 MPa. It is sufficient if it is 60 MPa or less, and 20 MPa or more is more preferable.
In this embodiment, the adhesive layer may have a storage elastic modulus of 0.01 to 0.5 MPa, preferably 0.01 to 0.4 MPa, and more preferably 0.03 to 0.3 MPa.

(Measurement method of tensile modulus, tensile stress and storage modulus)
A method for measuring the tensile modulus and tensile stress in this embodiment will be described with reference to FIG. FIG. 7 is a schematic plan view for explaining a sample for measuring tensile elastic modulus. A protective film to be measured is cut to a length of 50 mm × width of 30 mm to form a sample 32, which is set on a 35 mm SLIDE MOUNT 31 manufactured by Horsho to obtain a measurement sheet 33. The upper and lower portions of the measurement sheet 33 are fixed with a test piece gripping tool (chuck), and XY and X′-Y ′ of the measurement sheet 33 in FIG. The upper part is stretched at a pulling speed of 0.01 mm / sec, and the stress when stretched by 2% is measured. For the measurement, for example, a small desktop tensile tester (EZ-SX manufactured by Shimadzu Corporation) can be used. In this embodiment, values at 25 ° C. are used for the tensile modulus and tensile stress.

  The storage elastic modulus is obtained by stacking the pressure-sensitive adhesive layers to be measured so as to have a thickness of about 30 mm, removing bubbles with an autoclave, and then punching out to a diameter of 8 mm to obtain a cylindrical test piece. The upper and lower sides of the test piece are sandwiched between two circular plate jigs, and the storage elastic modulus (G ′) of the test piece is measured with a dynamic viscoelasticity measuring device at a frequency of 1 Hz and a temperature of 25 ° C. As the dynamic viscoelasticity measuring apparatus, for example, a dynamic viscoelasticity measuring apparatus “DYNAMIC ANALYZER RDA III” manufactured by TA Instruments Japan can be used.

<Other layer structure>
The touch panel device of the present embodiment may further have other layers as long as the effects of the present invention are not impaired.
Examples of the other layer include an adhesive layer that is provided between the first flexible base material and the transparent conductive layer in order to improve adhesion with the transparent conductive layer. As the pressure-sensitive adhesive for the pressure-sensitive adhesive layer provided between the first flexible base material and the transparent conductive layer, a known one may be used, and the protective film and the second flexible base material described above may be used. Between them, the same adhesive as the adhesive layer may be used.
Moreover, arbitrary layers can be provided in the surface on the opposite side to the transparent conductive layer of a 1st flexible base material and a 2nd flexible base material according to the use etc. of a touch panel device.

<Use of touch panel device>
The touch panel device of the present embodiment can be used particularly suitably for touch panel applications for flexible display devices because an increase in resistance value during bending is suppressed.

[Touch panel]
The touch panel of this embodiment includes the touch panel device on a display device. The layer configuration of the touch panel of this embodiment will be described with reference to the drawings. 5 and 6 are schematic cross-sectional views each showing an embodiment of a touch panel. The touch panel of FIG. 5 and FIG. 6 includes the touch panel device and the hard coat layer 14 on the image display surface of the display device 12. In the example of FIG. 5, the polarizing film 13 also functions as the second flexible substrate 5. In the example of FIG. 6, the display device 12 is the first flexible substrate 1, and the polarizing film 13 is the second flexible substrate 5.

  In the present embodiment, the display device 12 may be a liquid crystal display device (LCD) or an organic light emitting display device (OLED). The configurations of the liquid crystal display device and the organic light emitting display device can be appropriately selected from any conventionally known configurations.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this Example is demonstrated in detail, this Example is not limited only to the following Examples. “Part” means “part by mass” and “%” means “% by mass”. The compounding quantity in a table | surface is a mass part.

<Resin>
[Resin solution 1]
40 parts of Elitel UE-3200G (polyester, Mn 15,000, hydroxyl value 6 mg KOH / g, Tg 65 ° C., manufactured by Unitika) was dissolved in 60 parts of isophorone to obtain a resin solution 1 having a nonvolatile content of 40%.

[Resin solution 2]
40 parts of XA-0611 (polyester, Mn 17,000, hydroxyl value 4 mg KOH / g, Tg 65 ° C., manufactured by Unitika) was dissolved in 60 parts of isophorone to obtain a resin solution 2 having a nonvolatile content of 40%.

[Resin solution 3]
40 parts of YP-55U (phenoxy resin, Mn 10,000, hydroxyl value 198 mg KOH / g, Tg 84 ° C., manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) was dissolved in 60 parts of isophorone to obtain a resin solution 3 having a nonvolatile content of 40%.

[Resin solution 4]
40 parts of FX-293 (phenoxy resin, Mn 10,500, hydroxyl value 163 mg KOH / g, Tg 158 ° C., manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) was dissolved in 60 parts of isophorone to obtain a resin solution 4 having a nonvolatile content of 40%.

[Resin solution 5]
40 parts of BX-L (butyral resin, Mn 20,000, hydroxyl value 353 mg KOH / g, Tg 74 ° C., manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 60 parts of isophorone to obtain a resin solution 5 having a nonvolatile content of 40%.

[Resin solution 6]
40 parts of BX-5 (acetal resin, Mn 130,000, hydroxyl value 321 mg KOH / g, Tg 86 ° C., manufactured by Sekisui Chemical Co., Ltd.) was dissolved in 60 parts of isophorone to obtain a resin solution 6 having a nonvolatile content of 40%.

[Resin solution 7]
40 parts of CAB-551-0.2 (cellulose acetate butyrate resin, Mn 30,000, hydroxyl value 53 mg KOH / g, Tg 101 ° C., manufactured by Eastman Chemical Japan Co.) is dissolved in 60 parts of isophorone, and 40% non-volatile resin Solution 7 was obtained.

[Resin solution 8]
114 parts of UR-1370 (polyurethane, Mn 30,000, hydroxyl value 3 mg KOH / g, Tg 46 ° C., non-volatile content 35%, manufactured by Toyobo Co., Ltd.) was used as the resin solution 8 as it was.

[Resin solution 9]
133 parts of UR-8200 (polyurethane, Mn 25,000, hydroxyl value 4 mg KOH / g, Tg 73 ° C., nonvolatile content 30%, manufactured by Toyobo Co., Ltd.) was used as the resin solution 9 as it was.

[Resin solution 10]
100 parts of ZFR-1491H (bisphenol F acid-modified epoxy acrylate, non-volatile content 69%, manufactured by Nippon Kayaku Co., Ltd.) was used as the resin solution 10 as it was.

  The Mn, Tg and hydroxyl value of the resins (A) of the resin solutions 1 to 10 were determined according to the following method.

<Measurement of number average molecular weight (Mn)>
Apparatus: GPC (gel permeation chromatography)
Model: Shodex GPC-101 manufactured by Showa Denko
Column: Showa Denko GPCKF-G + KF805L + KF803L + KF802
Detector: Differential refractive index detector Shodex RI-71 manufactured by Showa Denko KK
Eluent: THF
Flow rate: Sample side: 1 mL / min Reference side: 0.5 mL / min Temperature: 40 ° C.
Sample: 0.2% THF solution (100 μL injection)
Calibration curve: A calibration curve was prepared using 12 standard polystyrenes with the following molecular weights manufactured by Tosoh Corporation.
F128 (1.09 × 10 ⁶ ), F80 (7.06 × 10 ⁵ ), F40 (4.27 × 10 ⁵ ), F20 (1.90 × 10 ⁵ ), F10 (9.64 × 10 ⁴ ), F4 (3.79 × 10 ⁴ ), F2 (1.81 × 10 ⁴ ), F1 (1.02 × 10 ⁴ ), A5000 (5.97 × 10 ³ ), A2500 (2.63 × 10 ³ ), A1000 (1.05 × 10 ³ ), A500 (5.0 × 10 ² ).
Baseline: The starting point of the first peak of the GPC curve was the starting point, and no peak was detected at a retention time of 25 minutes (molecular weight 3,150). The molecular weight was calculated using the line connecting both points as the baseline.

<Measurement of Tg>
・ Apparatus: Seiko Instruments differential scanning calorimeter DSC-220C
-Sample: about 10 mg (weigh to 0.1 mg)
・ Temperature increase rate: Measured up to 200 ° C. at 10 ° C./min. ・ Tg temperature: Draw at the point where the gradient is maximized on the low temperature side of the straight line and the melting peak on the low temperature side of the curve. The temperature at the intersection of the polygonal lines was used.

<Measurement of hydroxyl value>
The measurement was performed according to JISK0070.

<Crosslinking agent>
Cross-linking agent A: BI7982 (block isocyanate, base isocyanate: HDI trimer, block agent: DMP, dissociation temperature 110 ° C., non-volatile content 70%, cross-linking agent B: Sumidur BL3175 (block isocyanate, base isocyanate: Baxenden Chemicals Limited) (HDI, blocking agent: MEKO, non-volatile content 75%, manufactured by Sumika Covestro Urethane Co., Ltd.)
Crosslinking agent C: E402-B80B (block isocyanate, non-volatile content 80%, manufactured by Asahi Kasei Corporation)
Crosslinking agent D: IRGACURE907 (2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, non-volatile content 100%, BASF)
Cross-linking agent E: Esacure One (Nihon Shibel Hegner)
Crosslinking agent F: IRGACURE TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 100% nonvolatile content, BASF)

<Curing accelerator>
XK-614 (100% non-volatile content, manufactured by KINGINDUSTRIES)

<Monomer>
Monomer (1): ACMO (N-acryloylmorpholine, manufactured by KJ Chemicals)
Monomer (2): Miramer M220 (Tripropylene glycol diacrylate, manufactured by MIWON)
Monomer (3): M-406 (mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, manufactured by Toagosei Co., Ltd.)

<Antifoaming agent>
AC-326F (non-volatile content 100%, manufactured by Kyoeisha Chemical Co., Ltd.)

[Composition for protective film]
<Resin composition 1>
Resin solution 1: 100 parts, crosslinking agent A: 3.0 parts, solvent: 20.0 parts, antifoaming agent: 0.50
Parts, accelerator: 0.20 part was mixed with the planetary mixer, and the resin composition 1 was prepared.

<Resin compositions 2-9>
Resin compositions 2 to 9 were prepared in the same manner as in resin composition 1 except that the resin solution, crosslinking agent, accelerator, antifoaming agent, and solvent were mixed in the proportions shown in Table 1.

<Resin composition 10>
The resin composition 10 was prepared by mixing the resin solution 7, the crosslinking agent, the monomer (1), the monomer (2), and the solvent at a blending ratio shown in Table 1 using a planetary mixer.

<Resin composition 11>
The resin composition 11 was prepared by mixing the resin solution 10, the crosslinking agent, the monomer (3), and the solvent at a blending ratio shown in Table 1 with a planetary mixer. In Table 1, MEK represents methyl ethyl ketone.

<Preparation of tensile modulus measurement sheet>
The obtained resin composition was coated on a peelable sheet (commercially foamed PET film) using a doctor blade so that the thickness after drying was 20 μm.
Next, the resin compositions 1 to 9 were cured and dried in a 130 ° C. oven for 30 minutes, and then the commercially available foamed PET film was peeled to obtain test sheets 1 to 9.
The resin composition 10 was cured at a cumulative exposure of 500 mJ / cm ² using a high-pressure mercury lamp, and then the commercially available foamed PET film was peeled off to obtain a test sheet 10.
The resin composition 11 was temporarily dried in a 100 ° C. oven for 10 minutes. A positive pattern film having a length of 15 mm and a width of 70 mm was vacuum-adhered on the obtained coating film, and pattern exposure was performed with an integrated exposure amount of 1000 mJ / cm ² . Next, the unexposed portion was developed with a liquid temperature of 30 ° C. and a 1 wt% sodium carbonate aqueous solution for 30 seconds, washed with water, wiped off the surface moisture, dried in a 130 ° C. oven for 30 minutes, and then cured. The test foam 11 was obtained by peeling off the commercially available foamed PET film.
Thereafter, the obtained test sheets 1 to 11 were each cut to a length of 50 mm and a width of 30 mm to prepare a sample 32. The measurement sheet 33 was produced by setting the foam from the sample 32 in a 35 mm SLIDE MOUNT 31 manufactured by Horsho as shown in FIG.
-Foamed PET film: CN100 manufactured by Toyobo Co., Ltd. (thickness 50 μm)

<Measurement of film thickness>
The thickness of the test sheet in the obtained tensile modulus measurement sheet was measured using an MH-15M type measuring instrument (manufactured by Nikon Corporation).

<Evaluation of tensile modulus, tensile stress, and yield point>
With respect to the measurement sheet 33, the tensile modulus, the tensile stress when stretched by 2%, and the yield point were measured at 25 ° C. using a small desktop tensile tester (EZ-SX, manufactured by Shimadzu Corporation). The upper and lower portions of the measurement sheet 33 in FIG. 7 are fixed with a test piece gripping tool (chuck), and the distance between chucks is 23 mm after cutting XY and X′-Y ′ of the measurement sheet 33 in FIG. The upper part was stretched at a pulling rate of 0.01 mm / sec, and the stress and yield point when stretched by 2% were measured under the following conditions. The tensile elastic modulus was evaluated according to JIS K7161. Specifically, when the stresses corresponding to the two specified strains ε1 = 0.05% and ε2 = 0.25% are σ1 and σ2, respectively, the stress difference (σ2−σ1) is strained. The value obtained by dividing by the difference (ε2−ε1) was taken as the tensile elastic modulus (E) and obtained based on the following formula. The results are shown in Table 1.
E = (σ2−σ1) / (ε2−ε1)
E: Tensile modulus (MPa), σ: Tensile stress (MPa), ε: Tensile strain

<Adhesive>
[Adhesive 1]
In a nitrogen atmosphere in a reactor equipped with a stirrer, reflux condenser, nitrogen inlet tube, thermometer, and dropping tube, 1 part 2-hydroxyethyl acrylate, 69 parts n-butyl acrylate, 30 parts 2-ethylhexyl acrylate And 50% of the total amount of the monomer mixture containing an appropriate amount of ethyl acetate was charged into the reactor, and the remaining 50% was charged into the dropping tank. Next, an appropriate amount of azobisisobutyronitrile as a polymerization initiator was charged into the reactor and the dropping tank, respectively. The reactor was heated to confirm the start of the reaction, and a monomer mixture and the like were dropped from the dropping tank over 2 hours. After completion of the dropwise addition, the reaction was carried out at a solution temperature of about 80 ° C. for 5 hours. After completion of the reaction, cooling was performed, and then ethyl acetate was added so that the nonvolatile content was 40%, thereby obtaining an acrylic resin solution (1) having a weight average molecular weight of 1,000,000.
For 100 parts of the nonvolatile content of the resulting acrylic resin solution (1), 1 part of an isocyanate curing agent (adduct of trimethylolpropane of xylylene diisocyanate) and a silane coupling agent (3-glycidoxypropyltri 0.05 part of ethoxysilane) was mixed and sufficiently stirred to prepare adhesive 1.

[Adhesive 2]
Weight in the same manner as adhesive 1 except that the monomer for synthesizing the acrylic resin (1) solution was changed to 1 part 2-hydroxyethyl acrylate, 89 parts n-butyl acrylate, and 10 parts methyl acrylate. An acrylic resin solution (2) having an average molecular weight of 1 million was obtained.
0.5 parts of isocyanate curing agent (hexamethylene diisocyanate burette) and silane coupling agent (3-glycidoxypropyltriethoxysilane) with respect to 100 parts of the nonvolatile content of the resulting acrylic resin solution (2) ) Was mixed and stirred sufficiently to prepare an adhesive 2.

[Adhesive 3]
Except for changing the monomer for synthesizing the acrylic resin (1) solution to 1 part 2-hydroxyethyl acrylate, 69 parts n-butyl acrylate, and 30 parts methyl acrylate An acrylic resin solution (2) having an average molecular weight of 1 million was obtained.
0.5 parts of isocyanate curing agent (hexamethylene diisocyanate burette) and silane coupling agent (3-glycidoxypropyltriethoxysilane) with respect to 100 parts of the nonvolatile content of the resulting acrylic resin solution (2) ) Was mixed and stirred sufficiently to prepare an adhesive 3.

<Evaluation of storage modulus>
The obtained pressure-sensitive adhesive was coated on a peelable sheet so that the thickness after drying was 30 μm, and dried to form a pressure-sensitive adhesive layer. The obtained pressure-sensitive adhesive layer was laminated so as to have a thickness of about 30 mm, and then bubbles were removed by an autoclave. Subsequently, it was punched to a diameter of 8 mm to obtain a cylindrical test piece. The specimen was sandwiched between two circular plate jigs, and the storage elastic modulus (G ′) of the test piece was measured under the following conditions. The results are shown in Table 2.
Measuring device: Dynamic viscoelasticity measuring device “DYNAMIC ANALYZER RDA III” manufactured by TA Instruments Japan
Frequency: 1Hz
Temperature: 25 ° C

[Adhesive sheet 1]
The obtained pressure-sensitive adhesive 1 was coated on a release liner (thickness 38 μm polyethylene terephthalate (PET)) to a dry thickness of 25 μm using a comma coater and dried at 100 ° C. for 2 minutes. Then, a PET film having a thickness of 50 μm was bonded to the adhesive layer and aged for 7 days at 25 ° C. to obtain a substrate-less adhesive sheet 1 provided with the adhesive layer A.

[Adhesive sheets 2 and 3]
Except that adhesive 1 was changed to adhesives 2 and 3, respectively, the same procedure as adhesive sheet 1 was carried out, and base-less adhesive sheet 2 with adhesive layer B and base-less adhesive sheet 3 with adhesive layer C were used. Obtained. Separately, an adhesive sheet 3 having an adhesive layer C having a thickness of 25 μm or an adhesive layer C having a thickness of 65 μm was also prepared.

(Preparation of samples for flexibility test)
<Example 1>
This will be described with reference to FIG. FIG. 8 is a schematic (a) plan view and (b) side view for explaining a sample for a flexibility test. Screen printed so that the film thickness after drying a conductive paste (REXALPHA RA FS074, manufactured by Toyochem Co., Ltd.) on the ITO laminated film 51 becomes 5 μm, and a resistance value measuring terminal portion of 15 mm in length × 3.5 mm in width The 52-1 and the resistance value measuring terminal portion 52-2 were formed with an interval of 75 mm, dried for 30 minutes in a 135 ° C. oven, and cured.
Coating was performed on the ITO laminated film 51 with a resistance value measuring terminal so that the film thickness after drying the resin composition 1 was 7 μm, and a protective film 53 of 15 mm length × 70 mm width was formed. Next, the film sample on which the protective film 53 of the resin composition 1 was formed was dried and cured in a 130 ° C. oven for 30 minutes.
One peelable sheet of the pressure-sensitive adhesive sheet A was peeled off from the upper layer of the protective film 53, and the exposed pressure-sensitive adhesive layer was adhered using a laminator at 25 ° C. and a relative humidity of 50% RH to form a pressure-sensitive adhesive layer 54. Next, a 50 μm thick PET film 55 was laminated on the adhesive layer 54 to obtain a test sheet of Example 1.

<Examples 2 to 24>
In Example 1, test sheets of Examples 2 to 24 were prepared in the same manner as in Example 1 except that the materials and thicknesses of the protective film and the adhesive layer were changed as shown in Table 3.

<Example 25>
Screen printed so that the film thickness after drying a conductive paste (REXALPHA RA FS074, manufactured by Toyochem Co., Ltd.) on the ITO laminated film 51 becomes 5 μm, and a resistance value measuring terminal portion of 15 mm in length × 3.5 mm in width The 52-1 and the resistance value measuring terminal portion 52-2 were formed with an interval of 75 mm, dried for 30 minutes in a 135 ° C. oven, and cured. The resin composition 10 obtained on the ITO laminated film 51 with a resistance value measuring terminal was applied so that the film thickness after drying was 7 μm, and a protective film 53 of 15 mm length × 70 mm width was formed. Next, the film sample on which the protective film 53 of the resin composition 10 was formed was cured at a cumulative exposure amount of 500 mJ / cm ² using a high-pressure mercury lamp.
One peelable sheet of the pressure-sensitive adhesive sheet C was peeled off on the protective film 53, and the exposed pressure-sensitive adhesive layer was stuck using a laminator in an atmosphere of 25 ° C. and a relative humidity of 50% RH to form a pressure-sensitive adhesive layer 54. Next, a 50 μm thick PET film 55 was bonded onto the adhesive layer 54 to obtain a test sheet of Example 25.

<Example 26>
Screen printed so that the film thickness after drying a conductive paste (REXALPHA RA FS074, manufactured by Toyochem Co., Ltd.) on the ITO laminated film 51 becomes 5 μm, and a resistance value measuring terminal portion of 15 mm in length × 3.5 mm in width The 52-1 and the resistance value measuring terminal portion 52-2 were formed with an interval of 75 mm, dried for 30 minutes in a 135 ° C. oven, and cured. The resin composition 11 obtained on the ITO laminated film 51 with a resistance value measurement terminal was applied so that the film thickness after drying was 7 μm, and was temporarily dried in a 100 ° C. oven for 10 minutes. A positive pattern film having a length of 15 mm and a width of 70 mm was vacuum-adhered on the obtained coating film, and pattern exposure was performed with an integrated exposure amount of 1000 mJ / cm ² . Next, the unexposed portion was developed with a liquid temperature of 30 ° C. and a 1 wt% sodium carbonate aqueous solution for 30 seconds, washed with water, wiped off moisture on the surface, and then dried in a 130 ° C. oven for 30 minutes to be cured.
One peelable sheet of the pressure-sensitive adhesive sheet C is peeled off on the protective film 53, and the exposed pressure-sensitive adhesive layer is stuck using a laminator at 25 ° C. and a relative humidity of 50% RH to produce a test sheet of Example 26. did.

<Comparative Examples 1-2>
Screen printed so that the film thickness after drying a conductive paste (REXALPHA RA FS074, manufactured by Toyochem Co., Ltd.) on the ITO laminated film 51 becomes 5 μm, and a resistance value measuring terminal portion of 15 mm in length × 3.5 mm in width The 52-1 and the resistance value measuring terminal portion 52-2 were formed with an interval of 75 mm, dried for 30 minutes in a 135 ° C. oven, and cured. One peelable sheet of the pressure-sensitive adhesive sheet C is peeled off on the ITO laminated film 51, and the exposed pressure-sensitive adhesive layer is pasted using a laminator in an atmosphere of 25 ° C. and a relative humidity of 50% RH. A test sheet was prepared.

<Resistance value>
Flexibility tests were performed using the test sheets obtained in the examples and comparative examples, and changes in resistance values before and after the tests were evaluated.
When the resistance value is measured by directly applying a terminal to the ITO layer with a tester, the ITO layer is damaged and an accurate resistance value cannot be measured. Therefore, a resistance value measuring terminal portion is formed on the ITO with silver paste, and the tester is provided there. And the resistance value was measured.
-ITO laminated film: commercial product (surface resistance value of ITO layer: 150Ω / □, substrate: PET, thickness: 50 μm)

<Evaluation of resistance value change rate>
A flexibility test was performed using the obtained test sheet. The bendability test is performed using a bend resistance tester (manufactured by Yuasa System Equipment Co., Ltd., a planar body no-load U-shaped stretch tester), and set in the apparatus so that the protective film of the test sheet 3 is on the lower side. The sample was bent by 50,000 times at a temperature of 25 ° C. and a diameter of 4 mmφ at a speed of 30 times / minute. The change rate of the surface resistance value was calculated from the following formula. The results are shown in Tables 3 and 4.
Rate of change = (Surface resistance value after 50,000 bending bending before surface resistance test) / (Surface resistance value before test × 100)
・ Evaluation criteria ◎: Change rate is less than 5% (excellent)
○: Change rate is 5% or more and less than 20% (good)
Δ: Change rate of 20% or more and less than 30% (no problem in practical use)
X: Change rate is 30% or more (not practical)

[Summary of results]
As shown in Comparative Example 2, even if the touch panel device has only the pressure-sensitive adhesive layer on the transparent conductive layer, if the thickness of the pressure-sensitive adhesive layer is 110 μm, the resistance value change rate of the transparent conductive layer is practical. There was no problem above. However, as shown in Comparative Example 1, when the thickness is less than 100 μm, the decrease in the conductivity of the transparent conductive layer is 30% or more, which causes a practical problem.
The touch panel devices of Examples 1 to 26 having a protective film having predetermined physical properties on the transparent conductive layer and an adhesive layer are flexible even if the total thickness of the protective film and the adhesive layer is less than 100 μm. The resistance value change rate after the test was suppressed, and according to the present embodiment, it was revealed that a touch panel device in which an increase in resistance value during bending was suppressed was obtained.

DESCRIPTION OF SYMBOLS 1 1st flexible base material 2, 2a, 2b Transparent conductive layer 3 Protective film 4 Adhesive layer 5 2nd flexible base material 6 2nd transparent conductive layer 7 2nd protective film 8 2nd adhesive Layer 9 Third flexible substrate 11 Bridge structure 12 Display device 13 Polarizing film 14 Hard coat layer 31 SLIDE MOUNT
32 Sample 33 Measurement sheet 51 ITO laminated film 52-1, 52-2 Resistance value measurement terminal part 53 Protective film 54 Adhesive layer 55 PET film 10, 20, 30, 40 Touch panel device 50, 60 Touch panel

Claims (7)

On the first flexible substrate, it has a transparent conductive layer, a protective film, an adhesive layer, and a second flexible substrate in this order,
The total thickness of the protective film and the adhesive layer is less than 100 μm,
The protective film has a tensile modulus of 400 MPa to 4000 MPa at a tensile rate of 0.01 mm / second, and a tensile stress of 15 MPa to 60 MPa when stretched by 2%,
The touch panel device whose said adhesion layer is storage elastic modulus 0.01-0.5 Mpa.   The touch panel device according to claim 1, wherein the protective film has a thickness of 0.2 μm or more and 50 μm or less.   The touch panel device of Claim 1 or 2 whose thickness of the said adhesion layer is 2 micrometers or more and 95 micrometers or less.   The touch panel device according to claim 1, wherein the adhesive layer has a thickness larger than that of the protective film.   The touch panel device according to claim 1, wherein the protective film includes a resin having a ring structure.   The touch panel device as described in any one of Claims 1-5 in which the said adhesion layer contains acrylic resin.   A touch panel provided with the touch-panel device as described in any one of Claims 1-5.

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