TW201843188A - Protective film for touch panel electrode and touch panel - Google Patents

Abstract

According to one embodiment of the present invention, a protective film for a touch panel electrode is obtained by curing a photosensitive resin composition containing: a binder polymer having a weight average molecular weight of 100000 or more; a photopolymerizable compound; and a photopolymerization initiator.

Description

Protective film and touch panel of touch panel electrodes

The invention relates to a protective film and a touch panel of a touch panel electrode.

Display devices such as large-scale electronic devices such as personal computers and televisions, small-sized electronic devices such as car navigation, mobile phones, and electronic dictionaries, and office automation and factory automation (Office Automation, Factory Automation, OA, FA) equipment In the past, liquid crystal display elements and touch panels (touch sensors) have been used.

Touch panels have been put into practical use in various ways, and in recent years, touch panels using electrostatic capacitance have been advanced. In a projection type capacitive touch panel which is one type of capacitive touch panel, in order to express two-dimensional coordinates using the X-axis and the Y-axis, a plurality of X electrodes and a plurality of X electrodes are orthogonal thereto. The Y electrodes form a two-layer structure. As such electrodes, in recent years, conductive fibers represented by Ag, such as Ag nanowires and carbon nanotubes, Ag meshes, Cu meshes, and the like have been studied, but indium tin oxide (Indium-Tin-Oxide) has been studied. , ITO) is still the mainstream.

Moreover, the frame area of the touch panel is an area where the touch position cannot be detected. Therefore, reducing the area of the frame area is an important factor for improving the value of the product. In the frame area, in order to transmit the detection signal of the touch position, metal wiring is required. Usually, the metal wiring is formed of copper, silver, or the like.

However, when the touch panel as described above is in contact with the fingertip, corrosion components such as moisture and salt may intrude into the interior from the sensing region. When the corrosion component intrudes into the inside of the touch panel, the metal wiring may corrode, and there is a concern that the resistance between the electrode and the driving circuit increases, and the wire is broken.

In order to prevent corrosion of metal wiring, a capacitance type projection type touch panel in which an insulating layer is formed on a metal is disclosed (for example, Patent Document 1). In the touch panel, a ruthenium dioxide layer is formed on the metal by a plasma chemical vapor deposition (CVD) method to prevent corrosion of the metal. In addition, as another method, a method of providing a photosensitive layer containing a photosensitive resin composition on a predetermined substrate and exposing and developing the photosensitive layer is known (for example, Patent Document 2). In this method, a film-like resist film having a desired thickness is bonded to a substrate, and then exposure and development are carried out to form a resist film at a necessary portion. [Prior Art Document] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2011-28594 [Patent Document 2] International Publication No. 2013/084886

[Problems to be Solved by the Invention] In recent years, demands for thinning and weight reduction of displays, touch panels, and the like have been increasing. Along with this, a flexible substrate is used as the substrate. Further, the flexibility of the touch panel, the substrate, and the like (also referred to as "flexibility") in terms of the design and concept of the device is popularized by the wearable device. Demand is increasing year by year.

In such a flexible touch panel, since the ITO electrode is fragile, there is a problem that the resistance value of the touch panel electrode increases as the touch panel is bent. Heretofore, from the viewpoint of preventing corrosion of metal wiring, the application of the above-described protective film (insulating layer or resist film) has been studied, but the touch panel electrode is suppressed with the bending of the touch panel. From the viewpoint of an increase in the resistance value, there is no example of research.

The present invention has been made in view of such a practical situation, and an object of the invention is to provide a protective film capable of suppressing an increase in resistance of a touch panel electrode accompanying bending of a touch panel, and a touch panel including the same.

[Means for Solving the Problem] In order to solve the problem, the inventors of the present invention have made an effort to reduce the resistance value of the electrode when the touch panel is bent by forming a predetermined cured film on the electrode. The present invention has been completed.

The present invention is a protective film for a touch panel electrode, which is a photosensitive resin composition containing a binder polymer having a weight average molecular weight of 100,000 or more, a photopolymerizable compound, and a photopolymerization initiator. Hardened.

The inventors of the present invention considered the reason why the protective film can solve the problem as described below. When the protective film is not formed on the touch panel electrode provided on the substrate, when the touch panel is bent, the touch panel electrode cannot be followed by the substrate and is peeled off from the adhesive due to the occurrence of cracks. As a result, connection failure of the touch panel electrodes is caused, and the resistance value rises. On the other hand, when a predetermined protective film is formed on the touch panel electrode, when the touch panel is bent, even if the touch panel electrode cannot follow the substrate due to cracks, the protective film presses the touch panel electrode. Therefore, it is difficult to cause poor connection of the touch panel electrodes to each other. Therefore, it is considered that by forming a protective film on the touch panel electrodes, it is possible to suppress an increase in the resistance value of the touch panel.

The protective film is preferably disposed in a bent region of the touch panel.

The minimum value of the light transmittance in the protective film from 400 nm to 700 nm is preferably 90% or more.

The thickness of the protective film is preferably 50 μm or less.

In another aspect, the invention is a touch panel comprising: a substrate, an electrode disposed on the substrate, and the protective film disposed on the electrode.

[Effect of the Invention] According to the present invention, it is possible to provide a protective film capable of suppressing an increase in resistance of a touch panel electrode accompanying bending of a touch panel, and a touch panel including the same.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In the present specification, the touch panel electrode includes not only electrodes disposed in a sensing area (also referred to as a “touch screen area”) of the touch panel, but also included in the sensing area (touch screen area). The area is the metal wiring of the border area. The electrode on which the protective film is provided may be either one of an electrode provided in the sensing region and a metal wiring provided in the frame region, or both.

In the present specification, "(meth)acrylic acid" means "acrylic acid" or "methacrylic acid". The term "(meth)acrylate" means "acrylate" or "methacrylate".

In the present specification, the term "A or B" means at least one of A and B, that is, both A and B. Unless otherwise specified, the materials, components, and the like exemplified in the present specification may be used singly or in combination of two or more.

In the present specification, the term "step" refers not only to an independent step but also to the step as long as the intended effect of the step is achieved even if it cannot be clearly distinguished from other steps. In the present specification, the numerical values indicated by "~" include the numerical values described before and after "~" as the minimum value and the maximum value, respectively.

In the present specification, in the case where the content of each component in the composition is a plurality of substances corresponding to the respective components in the composition, unless otherwise specified, the total amount of the plurality of substances present in the composition is referred to. .

<Photosensitive Resin Composition> The photosensitive resin composition contains a binder polymer (also referred to as "(A) component)), a photopolymerizable compound (also referred to as "(B) component"), and photopolymerization initiation. Agent (also known as "(C) ingredient").

(Binder Polymer) The (A) component can be patterned by alkali development, and examples thereof include a binder polymer having a carboxyl group. The binder polymer having a carboxyl group is, for example, a copolymer containing a polymerizable monovalent body having a carboxyl group and another polymerizable unitary body as a constituent unit, and preferably has (a) (meth)acrylic acid, and (b) a copolymer of constituent units of an alkyl (meth)acrylate.

Examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Hydroxyethyl (meth)acrylate or the like.

The copolymer may further have, as a constituent unit, another monomer copolymerizable with at least one of the components (a) and (b). Examples of the other monomer copolymerizable with at least one of the component (a) and the component (b) include glycidyl (meth)acrylate, benzyl (meth)acrylate, and styrene. Dicyclopentyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and the like.

Among these, from the viewpoints of alkali developability, in particular, alkali developability, patterning property, and transparency of an inorganic alkaline aqueous solution, it is preferred to have a source derived from (meth)acrylic acid, (methyl) Glycidyl acrylate, benzyl (meth) acrylate, styrene, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate and 2-ethyl (meth) acrylate A binder polymer of structural units of at least one compound of the group consisting of hexyl hexyl esters.

The weight average molecular weight of the binder polymer as the component (A) is 100,000 or more, and from the viewpoint of more excellent film formability and flexibility, it is preferably 120,000 or more, more preferably 140,000 or more, and still more preferably 160,000 or more. The weight average molecular weight of the binder polymer is preferably 300,000 or less, more preferably 250,000 or less, and still more preferably 200,000 or less from the viewpoint of the resolution. In the present specification, the weight average molecular weight means a value obtained by the same measurement conditions as in the examples.

From the viewpoint of easily forming a protective film having a desired shape, the acidity of the binder polymer as the component (A) may be 75 mgKOH/g or more, thereby realizing the ease of suppressing the shape of the protective film and the protective film. From the viewpoint of the coexistence of rust prevention, it is preferably from 75 mgKOH/g to 200 mgKOH/g, more preferably from 75 mgKOH/g to 150 mgKOH/g, and still more preferably from 75 mgKOH/g to 120 mgKOH/g. The acid value of the binder polymer as the component (A) means a value obtained by the same measurement conditions as in the examples of the present specification.

The hydroxyl group value of the binder polymer as the component (A) is preferably 50 mgKOH/g or less, and more preferably 45 mgKOH/g or less, from the viewpoint of further improving the rust preventive property. The hydroxyl value of the component (A) means a value obtained by the same measurement conditions as in the examples of the present specification.

The content of the component (A) is preferably 35 parts by mass or more based on 100 parts by mass of the total of the components (A) and (B), from the viewpoint of maintaining transparency and preferably forming a desired pattern. It is more preferably 40 parts by mass or more, further preferably 50 parts by mass or more, and particularly preferably 55 parts by mass or more.

(Photopolymerizable Compound) The photopolymerizable compound having the ethylenically unsaturated group may be mentioned as the photopolymerizable compound of the component (B).

Examples of the photopolymerizable compound having an ethylenically unsaturated group include a monofunctional vinyl monomer having one polymerizable ethylenically unsaturated group in the molecule, and two polymerizable ethylenic groups in the molecule. A saturated difunctional vinyl monomer, a polyfunctional vinyl monomer having at least three polymerizable ethylenically unsaturated groups in the molecule, and the like.

The monofunctional vinyl monomer having a polymerizable ethylenically unsaturated group in the molecule is exemplified as a preferred one as the constituent unit of the component (A). (Meth)acrylic acid, alkyl (meth)acrylate, and a monomer copolymerizable therewith.

Examples of the difunctional vinyl monomer having two polymerizable ethylenically unsaturated groups in the molecule include polyethylene glycol di(meth)acrylate (the number of ethoxy groups is 2 to 14). , trimethylolpropane di (meth) acrylate, polypropylene glycol di (meth) acrylate (the number of propyl groups is 2 to 14); bisphenol A polyoxyethylene di acrylate (ie, 2, 2-bis(4-propenyloxypolyethoxyphenyl)propane), bisphenol A polyoxyethylene dimethacrylate (ie, 2,2-bis(4-methylpropenyloxypolyethylene) Oxyphenyl) propylene), bisphenol A diglycidyl ether diacrylate, bisphenol A diglycidyl ether dimethacrylate, etc.; polycarboxylic acid (phthalic anhydride, etc.) and having hydroxyl group and ethylenic property An esterified product of an unsaturated group (β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, etc.).

As the polyfunctional vinyl monomer having at least three polymerizable ethylenically unsaturated groups in the molecule, for example, a polyol obtained by reacting a polyol having at least three hydroxyl groups with an α,β-unsaturated carboxylic acid can be mentioned. a compound obtained by the addition reaction of a compound having at least three glycidyl groups with an α,β-unsaturated carboxylic acid, having a urethane bond in the molecule and at least three (meth) acrylonitrile groups A urethane monomer such as a (meth) acrylate compound.

Examples of the compound obtained by reacting a polyhydric alcohol with an α,β-unsaturated carboxylic acid include trimethylolpropane tri(meth)acrylate, tetramethylol methane tri(meth)acrylate, and tetra. Methyl hydroxymethane tetra(meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and the like.

Examples of the compound obtained by addition reaction of a compound having a glycidyl group with an α,β-unsaturated carboxylic acid include trimethylolpropane triglycidyl ether triacrylate.

Examples of the urethane monomer include tris((meth)acryloxytetraethyleneethylene glycol isocyanate) hexamethylene isocyanurate.

The component (B) is preferably a polyfunctional vinyl monomer having at least three polymerizable ethylenically unsaturated groups. The component (B) preferably contains a (meth) acrylate compound selected from a skeleton derived from pentaerythritol, and a skeleton derived from dipentaerythritol, from the viewpoint of suppressing corrosion of the electrode and easiness of development. At least one of a (meth) acrylate compound and a (meth) acrylate compound having a skeleton derived from trimethylolpropane, more preferably comprising (meth)acrylic acid selected from a skeleton derived from dipentaerythritol At least one of an ester compound and a (meth) acrylate compound having a skeleton derived from trimethylolpropane.

Here, the (meth) acrylate having a skeleton derived from dipentaerythritol means an esterified product of dipentaerythritol and (meth)acrylic acid. The esterified product also includes a compound modified with an alkyleneoxy group. The number of ester bonds in one molecule of the esterified product is preferably 6. The esterified product may also contain a compound having 1 to 5 ester bonds in one molecule.

The (meth) acrylate compound having a skeleton derived from trimethylolpropane means an esterified product of trimethylolpropane and (meth)acrylic acid. The esterified product also includes a compound modified with an alkyleneoxy group. The number of ester bonds in one molecule of the esterified product is preferably 3. The esterified product may also contain an esterified product having an ester bond number of 1 to 2 in one molecule.

From the viewpoint of obtaining the photocurability and the corrosion resistance of the electrode, the total amount of the photopolymerizable compound (component (B)) contained in the photosensitive resin composition is at least 100 parts by mass in the molecule. The proportion of the polyfunctional vinyl monomer having three polymerizable ethylenically unsaturated groups is preferably 30 parts by mass or more, more preferably 50 parts by mass or more, and still more preferably 75 parts by mass or more.

The content of the component (A) and the component (B) in the photosensitive resin composition is preferably 35 parts by mass based on 100 parts by mass of the total of the components (A) and (B). 85 parts by mass and (B) component is 15 parts by mass to 65 parts by mass, more preferably 40 parts by mass to 80 parts by mass of the component (A) and 20 parts by mass to 60 parts by mass of the component (B), and further preferably ( A) The component is 50 parts by mass to 70 parts by mass, and the component (B) is 30 parts by mass to 50 parts by mass, particularly preferably the component (A) is 55 parts by mass to 65 parts by mass and the component (B) is 35 parts by mass. 45 parts by mass.

When the content of the component (A) and the component (B) is within the above range, the coating property and the film property in forming a photosensitive element to be described later can be sufficiently ensured, and the sensitivity and light can be sufficiently ensured. Suppressibility, developability, and inhibition of electrode corrosion. In particular, the content of the component (A) is preferably 35 parts by mass or more, more preferably 100 parts by mass of the total of the components (A) and (B), in terms of maintaining the transparency and forming a good pattern. It is 40 parts by mass or more, more preferably 50 parts by mass or more, and particularly preferably 55 parts by mass or more.

The photopolymerization initiator as the component (C) may, for example, be an oxime ester compound or a phenylalkyl ketone compound. The (C) component is preferable in that the protective film is high in transparency and can be formed into a pattern with sufficient resolution even when the protective film is a film (for example, a film having a thickness of 10 μm or less). It is at least one selected from the group consisting of an oxime ester compound and a phenylalkyl ketone compound.

The oxime ester compound is, for example, a compound represented by the following formula (C-1). [Chemical 1]

In the formula (C-1), R ¹ represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 3 to 20 carbon atoms. Further, the compound represented by the formula (C-1) may have a substituent on the aromatic ring as long as the effects of the present invention are not inhibited. R ^{1 is} preferably an alkyl group having 3 to 10 carbon atoms or a cycloalkyl group having 4 to 15 carbon atoms, more preferably an alkyl group having 4 to 8 carbon atoms or a cycloalkyl group having 4 to 10 carbon atoms.

Examples of the compound represented by the formula (C-1) include 1,2-octanedione, 1-[4-(phenylthio)phenyl-, 2-(O-benzylidenehydrazine), and the like. 1,2-octanedione, 1-[4-(phenylthio)phenyl-, 2-(O-benzhydrylhydrazine)] can be used as IRGACURE OXE 01 (BASF Japan) ) (share), manufactured under the trade name).

The phenylalkyl ketone compound is a compound represented by the following formula (C-2) (2,2-dimethoxy-1,2-diphenylethane-1-one). [Chemical 2] 2,2-Dimethoxy-1,2-diphenylethane-1-one can be obtained as IRGACURE 651 (manufactured by BASF Japan Co., Ltd., trade name).

As the phenylalkyl ketone compound, in addition to the compound represented by the formula (C-2), for example, 1-hydroxy-cyclohexyl-phenyl-one, 2-hydroxy-2-methyl-1-benzene Base-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{ 4-[4-(2-hydroxy-2-methyl-propenyl)-benzyl]phenyl}-2-methyl-propan-1-one, 1.3α-aminophenylalkyl ketone, 2- Methyl-1-(4-methylthiophenyl)-2-morpholinylpropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl) -butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butene Ketones, etc. 1-Hydroxy-cyclohexyl-phenyl-ketone can be obtained as IRGACURE 184 (manufactured by BASF Japan Co., Ltd., trade name), 2-hydroxy-2-methyl-1-benzene The base-propan-1-one can be obtained as IRGACURE 1173 (manufactured by BASF Japan Co., Ltd., trade name), 1-[4-(2-hydroxyethoxy)-phenyl ]-2-hydroxy-2-methyl-1-propan-1-one can be obtained as IRGACURE 2959 (manufactured by BASF Japan Co., Ltd., trade name), 2-hydroxy-1 -{4-[4-(2-Hydroxy-2-methyl-propenyl)-benzyl]phenyl}-2-methyl-propan-1-one can be used as IRGACURE 127 (Japan) Obtained by BASF Japan (trade name).

The component (C) may be another photopolymerization initiator other than the oxime ester compound or the phenylalkyl ketone compound. Examples of the other photopolymerization initiator include aromatic ketones such as benzophenone and 4-methoxy-4'-dimethylaminobenzophenone; benzoin methyl ether, benzoin ethyl ether, and benzoin phenyl ether. A benzoin compound such as a benzoin ether compound, benzoin, methyl benzoin, ethyl benzoin or the like; a benzoin derivative such as benzoin dimethyl ketal; 9-phenyl acridine, 1,7-bis (9,9' - acridine derivative such as acridinyl)heptane; N-phenylglycine, N-phenylglycine derivative; coumarin compound; oxazole compound. As the component (C), a combination of a thioxanthone compound and a tertiary amine compound may be used in combination with diethyl thioxanthone and dimethylaminobenzoic acid.

The content of the component (C) is preferably 0.1 parts by mass or more, based on 100 parts by mass of the total of the components (A) and (B), from the viewpoint of the sensitivity and the resolution of the light. From the viewpoint of excellent light transmittance in the range of -700 nm, it is preferably 20 parts by mass or less. The content of the component (C) is preferably from 0.1 part by mass to 20 parts by mass, more preferably from 1 part by mass to 10 parts by mass, even more preferably 2%, based on 100 parts by mass of the total of the component (A) and the component (B). Parts by mass to 5 parts by mass.

In the case where a protective film is provided on a part of the ITO electrode of the touch panel, for example, the protective film is not formed in the sensing region, but the ITO electrode in the frame region and the copper are formed on the ITO electrode. In the case where a protective film is provided on a portion of the metal layer, the photosensitive layer may be provided on the entire surface (the entire surface of the touch panel), and then exposed and developed to remove unnecessary portions. In this case, it is required for the photosensitive layer to have sufficient adhesion to the electrode to be protected and good developability is required so that development residue does not occur in an unnecessary portion. The photosensitive resin composition of the present embodiment preferably contains a phosphate ester having an ethylenically unsaturated group (hereinafter, also referred to as a component (D), from the viewpoint of the adhesion between the photosensitive resin and the developer in this case. ). In the present specification, the phosphate containing an ethylenically unsaturated group may be overlapped with the component (B), but it is not included in the component (B).

From the viewpoint of sufficiently ensuring the rust resistance of the protective film and the adhesion between the ITO electrode and the developability at a high level, the phosphate having an ethylenically unsaturated group as the component (D) is preferably the following. A compound represented by the formula (D-1). The compound represented by the formula (D-1) can be obtained as a commercial product such as PM-21 (manufactured by Nippon Kayaku Co., Ltd.). [Chemical 3]

(Other additives) In addition, the photosensitive resin composition of the present embodiment may contain an adhesion imparting agent such as a decane coupling agent or the like, in an amount of 100 parts by mass based on the total amount of the component (A) and the component (B). 0.01 parts by mass to 20 parts by mass each of the agent, the plasticizer, the filler, the antifoaming agent, the flame retardant, the stabilizer, the antioxidant, the perfume, the thermal crosslinking agent, and the polymerization inhibitor. Further, the photosensitive resin composition may contain a water-soluble compound without significantly inhibiting the range of the function of the protective film.

The photosensitive resin composition of this embodiment can be used for forming a photosensitive layer. For example, a coating liquid can be prepared by uniformly dissolving or dispersing a photosensitive resin composition in a solvent, and applying the coating liquid to, for example, a support substrate, thereby forming a coating film and removing the solvent by drying. A photosensitive layer is formed.

The solvent is, for example, a ketone, an aromatic hydrocarbon, an alcohol, an ether, an ester, or a halogenated alkyl group, from the viewpoints of solubility of each component and easiness of formation of a coating film. Examples of the ketone include acetone, methyl ethyl ketone, and methyl isobutyl ketone. As an aromatic hydrocarbon, a toluene is mentioned, for example. As an alcohol, a monohydric alcohol and a glycol (diol) are mentioned. Examples of the monohydric alcohol include methanol, ethanol, propanol, butanol and the like. Examples of the diol include methyl glycol, ethylene glycol, and propylene glycol. Examples of the ether include an alkylene glycol alkyl ether and an alkylene glycol alkyl ether acetate. Examples of the alkylene glycol alkyl ether include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, and propylene glycol. Monomethyl ether. Examples of the alkanediol alkyl ether acetates include ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, and propylene glycol monomethyl ether acetate. Examples of the halogenated ester include chloroform, dichloromethane, and the like.

Examples of the coating method include known methods such as micro gravure coating, spin coating, dip coating, curtain coating, roll coating, spray coating, and slit coating.

The photosensitive resin composition of this embodiment is used for forming a protective film of a touch panel electrode, and is excellent in the adhesiveness with respect to the base material of a touchscreen. In the case where the touch panel has flexibility, the photosensitive resin composition is preferable for forming a protective film provided in a bent region of the touch panel. According to the photosensitive resin composition, generation of cracks in the electrode and the protective film when the touch panel is bent can be suppressed.

In order to protect the electrodes of the touch sensor, the photosensitive resin composition of the present embodiment is preferably used regardless of the type of the device in which the touch sensor is mounted. Examples of the device include a liquid crystal display device, an organic electroluminescence display device, a smart phone, and a tablet personal computer.

<Photosensitive Element> The photosensitive resin composition of the present embodiment is preferably formed into a film shape as in the case of a photosensitive element to be described later. By laminating a photosensitive film on a substrate having a touch panel electrode, the roll-to-roll process can be easily performed, and the solvent drying step can be shortened, which can greatly contribute to shortening of the manufacturing process and cost reduction.

Fig. 1(a) is a schematic cross-sectional view showing an embodiment of a photosensitive element. As shown in FIG. 1(a), the photosensitive element 1A includes a support film 2, and a photosensitive layer 3 containing the photosensitive resin composition provided on the support film 2.

The photosensitive element 1A is obtained, for example, by preparing a coating liquid containing the photosensitive resin composition of the present embodiment, applying the coating liquid onto the support film 2 to form a coating film, and drying the coating film. (The solvent is volatilized), whereby the photosensitive layer 3 is formed. The coating liquid can be obtained by uniformly dissolving or dispersing each component constituting the photosensitive resin composition of the present embodiment in a solvent.

The solvent is not particularly limited, and a known one can be used. The solvent can be similarly used as a solvent of the photosensitive resin composition.

Examples of the coating method include a knife coating method, a Meyer rod coating method, a roll coating method, a screen coating method, a spinner coating method, an inkjet coating method, and a spray coating method. A cloth method, a dip coating method, a gravure coating method, a curtain coating method, a die coating method, and the like.

The drying conditions are not particularly limited, and the drying temperature is preferably from 60 ° C to 130 ° C, and the drying time is preferably from 0.5 minute to 30 minutes.

(Support Film) As the support film 2, a polymer film can be used. The polymer film may, for example, be a film containing polyethylene terephthalate, polycarbonate, polyethylene, polypropylene, a cycloolefin polymer, or a polyether oxime.

The thickness of the support film 2 is preferably from 5 μm to 100 μm, more preferably from 10 μm to 70 μm, from the viewpoint of ensuring the coating property and suppressing the decrease in the resolution when the actinic ray is irradiated through the support film 2 . Further preferably, it is 15 μm to 40 μm, and particularly preferably 20 μm to 35 μm.

(Photosensitive layer) In order to exert a sufficient effect on the protection of the electrode, the step of the touch sensor surface formed by forming part of the electrode protective film is extremely small, and the thickness of the photosensitive layer 3 is dried (after the solvent is volatilized) The thickness of the film is preferably 20 μm or less, more preferably 1 μm or more and 9 μm or less, further preferably 1 μm or more and 8 μm or less, particularly preferably 2 μm or more and 8 μm or less, and preferably 3 μm. Above and below 8 μm.

The minimum value of the light transmittance in the photosensitive layer 3 from 400 nm to 700 nm is preferably 90% or more, more preferably 92% or more, and still more preferably 95% or more. When the minimum value of the light transmittance in the wavelength range of 400 nm to 700 nm, which is a general visible light wavelength range, is 90% or more, in the case of protecting the transparent electrode of the sensing region of the touch sensor And in the case where the protective layer is visible from the end of the sensing region when the metal layer of the frame region of the touch sensor is protected (for example, a layer on which the copper layer is formed on the ITO electrode), the sensing region can be sufficiently suppressed. The image shows a decrease in quality, hue, brightness, and the like.

In the present specification, the minimum value of the light transmittance in the photosensitive layer from 400 nm to 700 nm is obtained by measuring the light transmittance in the measurement wavelength range of 400 nm to 700 nm by using an ultraviolet-visible spectrophotometer. The minimum value of the light transmittance in the measurement wavelength range. After the photosensitive layer having a thickness of 10 μm or less formed on the support film was irradiated with ultraviolet rays and photocured, the light-transmitting photosensitive layer after the support film was peeled off was measured for light transmittance.

From the viewpoint of further improving the visibility of the touch panel, b ^* in the CIELAB color system of the photosensitive layer 3 is preferably from -0.2 to 1.0, more preferably from 0.0 to 0.7, still more preferably from 0.1 to 0.5. Similarly to the case where the minimum value of the light transmittance in the range of 400 nm to 700 nm is 90% or more, in the viewpoint of preventing the quality of the image display in the sensing region and the reduction in color tone, in the CIELAB color system b ^{* is} also preferably -0.2 to 1.0.

In the present specification, b ^* in the CIELAB color system refers to a value obtained by, for example, a spectrophotometer "CM-5" manufactured by Konica Minolta Co., Ltd., at D65. A photosensitive layer which was cured by irradiating ultraviolet rays on the photosensitive layer having a thickness of 10 μm or less formed on the support film and photocuring was measured under the conditions of a light source and a viewing angle of 2°.

The photosensitive element of the present embodiment may include other layers which are appropriately selected other than the photosensitive layer within a range in which the desired effect is obtained. The other layer is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include an optical adjustment layer, a buffer layer, an oxygen barrier layer, a release layer, and an adhesive layer. The photosensitive member may include one of the layers alone or in combination of two or more. The photosensitive element may also include two or more of the same layers.

(Protective Film) In another embodiment, as shown in FIG. 1(b), the photosensitive element 1B may further include, besides the support film 2 and the photosensitive layer 3, on the opposite side of the photosensitive layer 3 from the support film 2. Protective film (cover film) on the surface 4. That is, the photosensitive element 1B of one embodiment includes the support film 2, the photosensitive layer 3, and the protective film 4 in this order.

Examples of the protective film 4 include polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polyethylene-vinyl acetate copolymer, and polyethylene-vinyl acetate copolymer and polyethylene. A film such as a laminate film.

The thickness of the protective film 4 is preferably from 5 μm to 100 μm. The thickness of the protective film 4 is preferably 70 μm or less, more preferably 60 μm or less, further preferably 50 μm or less, and particularly preferably 40 μm from the viewpoint of storing the photosensitive element 1B in a roll shape. the following.

The photosensitive element 1A and the photosensitive element 1B can be wound in a roll shape and stored or used.

The photosensitive element 1A and the photosensitive element 1B are preferably formed of a photosensitive layer 3 formed of the photosensitive resin composition, and are preferably formed of a protective film for forming a touch panel electrode. A protective film with excellent adhesion.

<Touch Panel> FIGS. 2( a ) and 2 ( b ) are schematic diagrams showing an example of a capacitive touch panel. 2(a) is a schematic plan view of the touch panel, and FIG. 2(b) is a partial cross-sectional view taken along line I-I of the portion C shown in FIG. 2(a).

As shown in FIGS. 2( a ) and 2 ( b ), the touch panel 5 includes a substrate (transparent substrate) 6 and a touch panel electrode disposed on the substrate 6 . A touch screen area 7 for detecting a touch position coordinate is formed on one side of the touch panel 5. As the touch panel electrode, a first transparent electrode 8, a second transparent electrode 9, a metal wiring (lead wiring) 10, a connection electrode 11, and a connection terminal 12 are provided.

The substrate 6 including the touch panel electrodes shown in FIGS. 2(a) and 2(b) can be obtained, for example, by the following procedure. After forming a metal film in the order of ITO or Cu by sputtering on a substrate 6 such as a PET film, a photosensitive film for etching is attached to the metal film to form a desired resist pattern, and an aqueous solution of ferric chloride or the like is used. After the etching solution removes unnecessary Cu, the resist pattern is peeled off.

Examples of the substrate 6 include a substrate such as a glass plate, a plastic plate, or a ceramic plate which is generally used for a touch sensor. Examples of the touch panel electrode include electrodes formed of ITO, Cu, Al, Mo, or the like.

In order to detect a change in electrostatic capacitance, the first transparent electrode 8 and the second transparent electrode 9 are provided in the touch screen region 7. The first transparent electrode 8 and the second transparent electrode 9 detect the X coordinate and the Y coordinate of the touch position, respectively.

The metal wiring 10 transmits a detection signal of the touch position of the first transparent electrode 8 and the second transparent electrode 9 to an external circuit. The metal wiring 10 and the first transparent electrode 8 and the second transparent electrode 9 are connected to each other by the connection electrode 11 provided on the first transparent electrode 8 and the second transparent electrode 9. One end of the metal wiring 10 is connected to the first transparent electrode 8 and the second transparent electrode 9. The other end of the metal wiring 10 is provided with a connection terminal 12 to an external circuit.

As shown in FIG. 2( a ), the protective film 13 is disposed so as to cover the first transparent electrode 8 , the second transparent electrode 9 , the metal wiring 10 , and the connection electrode 11 and a part of the connection terminal 12 . The protective film 13 can be directly adhered to the touch panel electrode and the substrate 6 such as the metal wiring 10, or can be provided on the touch panel electrode and the substrate 6 of the metal wiring 10 or the like via another layer. The protective film 13 is preferably formed using the photosensitive resin composition or the photosensitive element of the present embodiment.

<Method of Forming Protective Film> [Layer Forming Step] The protective film 13 is formed, for example, in the following manner. First, a photosensitive layer containing the photosensitive resin composition is provided on a substrate 6 on which an electrode (touch panel electrode) such as the metal wiring 10 is provided (layer formation step). In the layer forming step, when a photosensitive element is used, the photosensitive layer is provided, for example, by heating the photosensitive element while pressing the surface of the substrate 6 with the metal wiring 10 or the like. The transfer is carried out and layering is carried out. Further, in the case where the photosensitive element 1B including the protective film 4 is used as the photosensitive element, the protective film 4 is removed before the pressure bonding. The photosensitive element may be rectangularly removed only by the connection portion with the other substrate, and then transferred to the substrate.

As a crimping mechanism, a crimping roller is mentioned. The crimping roller may also include a heating mechanism to allow for thermocompression bonding.

In order to sufficiently ensure the adhesion between the photosensitive layer and the substrate 6, and the adhesion between the photosensitive layer and the touch panel electrode, it is difficult to thermally cure or thermally decompose the constituent components of the photosensitive layer, and the heating temperature at the time of heating and pressure bonding is preferably performed. It is 10 ° C to 160 ° C, more preferably 20 ° C to 150 ° C, and still more preferably 23 ° C to 150 ° C.

On the side of the photosensitive layer to ensure sufficient adhesion to the substrate 6, while suppressing deformation of the base 6 of the viewpoint, the crimping pressure of thermocompression bonding is good regardless linear pressure 50 N / m ~ 1 × 10 5 N More preferably, it is from 2.5 × 10 ² N/m to 5 × 10 ⁴ N/m, and more preferably from 5 × 10 ² N/m to 4 × 10 ⁴ N/m.

When the photosensitive element is heated as described above, it is not necessary to preheat the substrate 6, but in order to further improve the adhesion between the photosensitive layer and the substrate 6, it is preferred to pretreat the substrate 6. Heat treatment. The preheating temperature at this time is preferably from 30 ° C to 150 ° C.

If necessary, it is also possible to apply an equal pressure by the compressed air while heating in the autoclave or in the middle of the heating and pressure bonding, thereby removing the bubbles of the photosensitive element and improving the crimp strength.

In another embodiment, instead of using a photosensitive element, a photosensitive layer may be formed by preparing a coating liquid containing the photosensitive resin composition of the present embodiment and a solvent, and applying the coating liquid to the substrate 6 The surface of the electrode is dried.

[Exposure Step] After the layer formation step, the entire surface of the photosensitive layer is irradiated with actinic rays to form a protective film containing a cured product of the photosensitive layer (exposure step).

When the actinic ray is irradiated, when the support film on the photosensitive layer is transparent, the actinic ray can be directly irradiated, and when it is opaque, the support film is removed and the actinic ray is irradiated. In terms of protecting the photosensitive layer, it is preferred to use a transparent polymer film as a support film, and to irradiate the actinic ray by transmitting the polymer film while leaving the polymer film. In this case, the support film is removed after irradiating the actinic ray.

A known active light source can be used as the light source of the actinic ray used for irradiating the actinic ray, and is not particularly limited as long as it is effective to emit ultraviolet rays. Examples of the light source include a metal halide lamp, a carbon arc lamp, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a xenon lamp, and the like.

The irradiation amount of the actinic rays at this time is usually 1 × 10 ² J/m ² to 1 × 10 ⁴ J/m ² , and may be accompanied by heating at the time of irradiation. When the irradiation amount of the actinic ray is 1×10 ² J/m ² or more, the effect of photocuring tends to be sufficient, and when it is 1×10 ⁴ J/m ² or less, discoloration of the photosensitive layer can be suppressed. Propensity.

In order to exert a sufficient effect on the protection of the electrode, and the step of the touch sensor surface formed by forming part of the electrode protective film is extremely small, the thickness of the protective film 13 is preferably 50 μm or less or 20 μm or less. It is preferably 1 μm or more and 9 μm or less, more preferably 1 μm or more and 8 μm or less, particularly preferably 2 μm or more and 8 μm or less, and most preferably 3 μm or more and 8 μm or less. The protective film 13 can suppress an increase in the resistance value of the touch panel electrode accompanying the bending of the touch panel even in the case of the above-described film.

The minimum value of the light transmittance in the protective film 13 from 400 nm to 700 nm is preferably 90% or more, more preferably 92% or more, and still more preferably 95% or more from the viewpoint of excellent visibility. In the case where the light transmittance of the protective film in the wavelength range of 400 nm to 700 nm, which is a general visible light wavelength range, is 90% or more, in the case of protecting the transparent electrode of the sensing region of the touch sensor And in the case where the protective layer is visible from the end of the sensing region when the metal layer of the frame region of the touch sensor is protected (for example, the copper layer formed on the ITO electrode), the sensing region can be sufficiently suppressed. The image display quality, hue, and brightness are reduced.

The b ^* in the CIELAB color system of the protective film 13 is preferably from -0.2 to 1.0, more preferably from 0.0 to 0.7, even more preferably from 0.1 to 0.5, from the viewpoint of excellent visibility.

In other embodiments, the substrate 6 may further include an optical adjustment layer (also referred to as an "index matching layer"), an insulating layer, or the like.

In the touch panel, the metal wiring 10 and the first transparent electrode 8 and the second transparent electrode 9 are connected to each other by the connection electrode 11, and in other aspects, the metal wiring, the first transparent electrode, and the second transparent The electrodes can also be connected directly to each other.

In other embodiments, the portion where the protective film 13 is provided may be appropriately changed. In the touch panel, the protective film 13 is provided to cover all of the first transparent electrode 8, the second transparent electrode 9, the metal wiring 10, and the connection electrode 11, and a part of the connection terminal 12, and may cover the first transparent electrode. A part of each of the second transparent electrode and the connection terminal, and all of the metal wiring and the connection electrode are provided. In this case, the protective film 13 is provided, for example, in the following manner. First, in the exposure step, a predetermined portion of the photosensitive layer is irradiated with an actinic ray through a mask to harden the photosensitive layer. The photosensitive layer irradiated with the actinic ray is developed with a developing solution, and a portion that is not irradiated with the actinic ray (that is, other than a predetermined portion of the photosensitive layer) is removed, thereby forming a protective film 13 of a part of the coated electrode (development step ). The protective film 13 contains a cured product of the photosensitive resin composition of the present embodiment and has a predetermined pattern. In the present specification, the pattern is not limited to the shape of the fine wiring forming the circuit, and includes a shape in which only the connection portion with the other substrate is removed in a rectangular shape, and only the sensing region of the substrate is removed. Wait.

[Developing Step] After the actinic ray is irradiated, when the support film is laminated on the photosensitive layer, it may be removed, and if necessary, the portion which is not irradiated with the actinic ray may be irradiated by the developing solution. Removal (development step).

The development step can be carried out by a known method such as spraying, spraying, shaking, brushing, or scrubbing using a known developing solution such as an aqueous alkaline solution, an aqueous developing solution, or an organic solvent. Among them, from the viewpoint of environment and safety, the development step is preferably carried out by using an alkaline aqueous solution and developing by spraying.

The development temperature and time can be adjusted according to the developability of the photosensitive resin composition of the present embodiment.

Further, after development, an alkali solution of an alkaline aqueous solution remaining on the photosensitive layer after photohardening may be subjected to an acid treatment using an organic acid, an inorganic acid or an aqueous solution of the acids by a known method such as spraying, shaking, scouring, scrubbing or scrubbing. (neutralization processing). Further, the water washing step may be performed after the acid treatment (neutralization treatment).

[Post Step] After curing by irradiation with actinic rays, after development, the photosensitive layer may be irradiated with actinic rays (for example, 5 × 10 ³ J/m ² to 2 × 10 ⁴ J/m ² ) as needed. The cured film is further hardened (post step). Further, the photosensitive resin composition of the present embodiment exhibits excellent adhesion to the metal even in the absence of the heating step after development, but may be replaced with the actinic ray after development or the actinic ray as needed. Heat treatment (80 ° C to 160 ° C) was carried out by irradiation.

The touch panel 5 can also have flexibility. Fig. 3 (a) is a perspective view showing an example of a touch panel having flexibility. Fig. 3(b) is a cross-sectional view taken along line II-II shown in Fig. 3(a). As shown in FIG. 3( a ) and FIG. 3( b ) , the touch panel 5A includes a touch panel substrate 14 and a protective film 13 disposed on the touch panel substrate 14 . 3(a) and 3(b), the substrate 6 and the touch panel electrodes in FIGS. 2(a) and 2(b) are collectively referred to as a touch panel substrate for simplification. 14. That is, the touch panel 5A includes a substrate 6, a touch panel electrode provided on the substrate 6, and a protective film 13 provided to cover at least a portion of the touch panel electrode.

The flexible touch panel 5A is bent in the vertical direction with respect to the XY plane (the -Z direction, the opposite side of the touch panel substrate 14 from the protective film 13) in the vicinity of both end portions in the X direction. A bending region R1 extending in the Y direction. The protective film 13 is provided on at least a portion of the bending region R1.

In the present specification, the bending region refers to a region that is bent at a predetermined radius of curvature or a region that can be bent with a predetermined radius of curvature. The predetermined radius of curvature is, for example, 40 mm or less, 10 mm or less, or 5 mm or less.

In other embodiments, the touch panel can also be folded in the bending area. In addition, in other embodiments, the touch panel may have a bent region near the central portion thereof.

4(a) and 4(b) are perspective views showing another example of a flexible touch panel. As shown in FIG. 4( a ), in one embodiment, the touch panel 5B has a protective film 13 in the vicinity of the center portion in the Y direction, and is along the XY plane direction (−Y direction, and the touch panel 5B). The main face is folded in a horizontal direction by 180° (also referred to as an inner bend) and has a bent region R2 extending in the X direction. The protective film 13 is provided on at least a portion of the bending region R2.

In addition, as shown in FIG. 4(b), in one embodiment, the touch panel 5C has a protective film 13 in the vicinity of the center portion in the Y direction, and is along the XY plane direction (-Y direction, and touch). The main surface of the panel 5B is folded in a horizontal direction by 180° (also referred to as an outer bend), and has a bent region R3 extending in the X direction. The protective film 13 is provided on at least a portion of the bending region R3.

The protective film 13 is excellent in adhesion to the touch panel substrate 14 (substrate 6) by the formation of the photosensitive resin composition, and therefore has a flexible touch panel 5A and touch as described above. The panel 5B and the touch panel 5C are preferably used. In addition, the protective film 13 can suppress the occurrence of cracks in the bent touch panel 5A, the touch panel 5B, the touch panel electrodes of the touch panel 5C, and the protective film 13. Further, by using the protective film 13, the increase in the resistance value in the touch panel electrode can also be suppressed. [Examples]

Hereinafter, the present invention will be more specifically described by way of examples. However, the present invention is not limited to the following examples.

[Preparation of the binder polymer solution (A1)] (1) shown in Table 1 was placed in a flask including a stirrer, a reflux condenser, an inert gas inlet, and a thermometer. The temperature was raised to 80 ° C in a nitrogen atmosphere, and (2) shown in Table 1 was uniformly added dropwise over 4 hours while maintaining the reaction temperature at 80 ° C ± 2 ° C. After the dropwise addition (2), stirring was continued at 80 ° C ± 2 ° C for 6 hours to obtain a solution of a binder polymer (solid content: 45 mass%) (A1). The binder polymer had a weight average molecular weight of 65,000, an acid value of 91 mgKOH/g, a hydroxyl value of 2 mgKOH/g, and a glass transition temperature (Tg) of 70 °C.

[Preparation of the binder polymer solution (A2)] A solution of the binder polymer was prepared in the same manner as the solution (A1) of the binder polymer, except that the amount of the input (2) shown in Table 1 was changed. (A2). The binder polymer had a weight average molecular weight of 180,000, an acid value of 91 mgKOH/g, a hydroxyl value of 2 mgKOH/g, and a glass transition temperature (Tg) of 75 °C.

[Preparation of the binder polymer solution (A3)] A solution of the binder polymer was prepared in the same manner as the solution (A1) of the binder polymer, except that the amount of the input (2) shown in Table 1 was changed. (A3). The binder polymer (A3) had a weight average molecular weight of 290,000, an acid value of 91 mgKOH/g, a hydroxyl value of 2 mgKOH/g, and a glass transition temperature (Tg) of 77 °C.

[Table 1]

The weight average molecular weight (Mw) is determined by using gel permeation chromatography (GPC) and converted using a standard curve of standard polystyrene. The conditions of GPC are shown below. GPC Condition Pump: Hitachi L-6000 (manufactured by Hitachi, Ltd., product name) Column: Gelpack GL-R420, Gelpack GL-R430, Gelpack GL-R440 (above, manufactured by Hitachi Chemical Co., Ltd., product name) Isolation liquid: tetrahydrofuran measurement temperature: 40 ° C Flow rate: 2.05 mL / min Detector: Hitachi L-3300 type RI (manufactured by Hitachi, Ltd., product name)

[Method for Measuring Acid Value] The acid value is measured by a neutralization titration method based on Japanese Industrial Standard (JIS) K0070 as shown below. First, a solution of the binder polymer was heated at 130 ° C for 1 hour to remove volatile components to obtain a solid component. Further, after accurately weighing 1 g of the binder polymer of the solid component, 30 g of acetone was added to the binder polymer to uniformly dissolve it to obtain a resin solution. Then, an appropriate amount of phenolphthalein as an indicator was added to the resin solution, and neutralization titration was carried out using a 0.1 mol/L potassium hydroxide aqueous solution. Further, the acid value was calculated according to the following formula. Acid value = 0.1 × V × f ₁ × 56.1 / (Wp × I / 100) wherein V represents the titer (mL) of a 0.1 mol/L potassium hydroxide aqueous solution for titration, and f ₁ represents 0.1 mol/L The factor (concentration conversion factor) of the aqueous potassium hydroxide solution, Wp represents the mass (g) of the measured resin solution, and I represents the ratio (% by mass) of the nonvolatile component in the measured resin solution.

[Method for Measuring Hydroxyl Value] The hydroxyl value is measured by a neutralization titration method according to JIS K0070 as shown below. First, a solution of the binder polymer was heated at 130 ° C for 1 hour to remove volatile components to obtain a solid component. Moreover, after accurately weighing 1 g of the binder polymer of the solid component, the binder polymer was placed in an Erlenmeyer flask, 10 mL of a 10% by mass solution of acetic anhydride pyridine was added, and the binder polymer was uniformly dissolved. Heat at 100 ° C for 1 hour. After heating, 10 mL of water and 10 mL of pyridine were added and heated at 100 ° C for 10 minutes, and then an automatic titrator (manufactured by Hiranuma Satoshi Co., Ltd., product name: COM-1700) was used, with 0.5 mol/L. The ethanol solution of potassium hydroxide was subjected to neutralization titration. Further, the hydroxyl value was calculated according to the following formula. Hydroxyl value = (AB) × f ₂ × 28.05 / S + D where A represents the amount (mL) of a 0.5 mol/L potassium hydroxide ethanol solution used for the blank test, and B represents a 0.5 mol/L hydroxide used for titration. The amount (mL) of the potassium ethanol solution, f ₂ represents a factor of 0.5 mol/L potassium hydroxide ethanol solution (concentration conversion factor), S represents the mass (g) of the binder polymer, and D represents the acid value. Further, the blank test was carried out without placing the binder polymer.

(Example 1) [Preparation of coating liquid containing photosensitive resin composition] The material shown in Table 2 was mixed for 15 minutes using a stirrer to prepare a coating containing a photosensitive resin composition for forming a protective film. liquid.

[Production of Photosensitive Element] As the support film, a polyethylene terephthalate film having a thickness of 50 μm was used. The produced coating liquid containing the photosensitive resin composition was uniformly applied onto the support film by a notch wheel coater. The solvent was removed by a hot air convection dryer at 100 ° C for 3 minutes to form a photosensitive layer (photosensitive resin composition layer) containing a photosensitive resin composition. The obtained photosensitive layer had a thickness of 5 μm.

Then, a polyethylene film having a thickness of 25 μm was attached to the obtained photosensitive layer as a protective film to prepare a photosensitive member for forming a protective film.

[Preparation of sample for bending resistance test] ITO with ITO (manufactured by Nitto Denko Co., Ltd., product name: V100-G2YC5B) ITO with L/S=200 μm/30 μm by laser patterning device Electrode pattern. A conductive paste (manufactured by Toyobo Co., Ltd., product name: DY-150H-30) was dispensed to the electrode pad, and dried by a hot air convection dryer at 140 ° C for 30 minutes to dry the solvent, and an ITO was annealed to produce a bending resistance. The test used ITO-TEG.

The obtained photosensitive element was laminated on ITO in such a manner that the ITO-TEG ITO was in contact with the photosensitive layer at a roll temperature of 110 ° C, a substrate transfer speed of 0.6 m/min, and a pressure contact pressure (cylinder pressure) of 0.4 MPa. On the -TEG, a laminate in which a photosensitive layer and a polyethylene terephthalate film were laminated on ITO-TEG was produced.

The obtained laminate was produced by using an ultraviolet transfer device (Orc), device name: QRM-2317F-00, and the exposure amount was 500 mJ from the upper side of the polyethylene terephthalate film. /m ² (measured value at i-ray (wavelength: 365 nm)) is irradiated with ultraviolet rays. Then, the support film laminated on the photosensitive layer was peeled off to obtain a sample for bending resistance test of a cured product having a photosensitive layer having a thickness of 5 μm.

[Bending resistance test] Next, a bending resistance test was carried out. <Outer bending (ITO stretching direction)> The bending test sample was placed on a surface load U-shaped stretching tester with a radius of curvature of 0.5 mm, 1 mm, and 1.5 mm, respectively. On the apparatus (device), device name: DLDMLH-FS, the ITO was bent once in the stretching direction at 11 rpm. <Inner bending (ITO compression direction)> The bending test sample was placed on a surface load U-shaped stretching tester (yuasa-system) equipment (unit) with a radius of curvature of 1 mm. Name: DLDMLH-FS), the ITO was bent 200,000 times in the compression direction at 60 rpm.

The bending resistance was evaluated according to the following criteria. The results are shown in Table 2. <Number of cracks> The bent sample was observed by an optical microscope (manufactured by Olympus Co., Ltd., device name: BX51), and the number of cracks was measured. <Resistance Change Rate> Before and after the bending resistance test, the tester was pressed to a conductive paste, and the resistance value was measured, and the resistance value change rate was calculated according to the following formula. Resistance change rate (%) = {(resistance value before bending resistance test - resistance value after bending resistance test) / resistance before bending resistance test value × × 100 Further, the resistance value exceeded the detection upper limit of the test machine The case where the measurement cannot be performed is set to "OL".

[Measurement of light transmittance, hue, and optical characteristics of the photosensitive layer] The protective film of the photosensitive element obtained, that is, the polyethylene film, was peeled off and the photosensitive layer was adhered to a glass substrate having a thickness of 0.7 mm. Laminating machine (manufactured by Hitachi Chemical Co., Ltd., trade name: HLM-3000), laminated at a roll temperature of 110 ° C, a substrate transfer speed of 0.6 m/min, and a pressure contact pressure (cylinder pressure) of 0.4 MPa. A laminate of a photosensitive layer and a support film is laminated on the glass substrate.

Then, the photosensitive layer laminate obtained using a parallel ray exposing machine (Oak (by Orc) manufactured by () manufactured, EXM1201), from above the photosensitive layer side of an exposure amount 1000 mJ / m ² (i-rays (wavelength The measured value at 365 nm) was irradiated with ultraviolet rays. Thereafter, the support film was removed to obtain a sample for measuring transmittance of a cured film having a photosensitive layer having a thickness of 5 μm.

Then, the obtained sample was measured for light transmittance in a measurement wavelength range of 400 nm to 700 nm using an ultraviolet-visible spectrophotometer (U-3310) manufactured by Hitachi High-Technologies Co., Ltd., and the minimum value was calculated. In addition, a spectrophotometer CM-5 manufactured by Konica Minolta Co., Ltd. was used for the obtained sample, and L ^* , a ^* , b ^* in the CIELAB color system was measured under the light source D65 ^. . Further, the obtained sample was measured for total light transmittance and haze using a haze meter and a turbidimeter (manufactured by Nippon Denshoku Industries Co., Ltd., device name: NDH 7000). The results are shown in Table 2.

(Examples 2 to 4 and Comparative Example 1) A protective film was formed using a photosensitive member in the same manner as in Example 1 except that the composition of the photosensitive resin composition was changed as shown in Table 2, and the protective film was formed. Test and measurement. The results are shown in Table 2.

[Table 2]

Further, the symbols of the components in Table 2 indicate the following meanings. (B) Component TMPTA: Trimethylolpropane triacrylate (manufactured by Nippon Kayaku Co., Ltd.) T-1420(T): Di-trimethylolpropane tetraacrylate (manufactured by Nippon Kayaku Co., Ltd.) ( C) Component BDK (IRGACURE 651): 2,2-dimethoxy-1,2-diphenylethane-1-one (manufactured by BASF Japan Co., Ltd.) (D) ) Component PM-21: Phosphate containing photopolymerizable unsaturated bond (manufactured by Nippon Kayaku Co., Ltd.) (Other components) DEAA: diethyl acrylamide (manufactured by KJ chemicals) Additive (ADDITIVE) 8032: Organic Modified Emu Oil (Manufactured by Toray Dow Corning Co., Ltd.) Antage W-500: 2,2'-methylene-bis(4-ethyl- 6-Tertibutylphenol) (Manufactured by Kawaguchi Chemical Industry Co., Ltd.)

1A, 1B‧‧‧Photosensitive components

2‧‧‧Support film

3‧‧‧Photosensitive layer

4‧‧‧Protective film

5, 5A, 5B, 5C‧‧‧ touch panel

6‧‧‧Substrate

7‧‧‧ touch screen area

8‧‧‧1st transparent electrode

9‧‧‧2nd transparent electrode

10‧‧‧Metal wiring

11‧‧‧Connecting electrode

12‧‧‧Connecting terminal

13‧‧‧Protective film

14‧‧‧Touch panel substrate

C‧‧‧ Section

R1, R2, R3‧‧‧ bending area

1(a) and 1(b) are schematic cross-sectional views showing an embodiment of each photosensitive element. Fig. 2(a) is a schematic plan view showing an aspect of a capacitive touch panel. Fig. 2(b) is a partial cross-sectional view taken along line I-I of the portion C shown in Fig. 2(a). Fig. 3 (a) is a perspective view showing an example of a touch panel having flexibility. Fig. 3(b) is a cross-sectional view taken along line II-II shown in Fig. 3(a). 4(a) and 4(b) are perspective views showing another example of a flexible touch panel.

Claims (5)

A protective film for a touch panel electrode obtained by curing a photosensitive resin composition containing a binder polymer having a weight average molecular weight of 100,000 or more, a photopolymerizable compound, and a photopolymerization initiator. The protective film of the touch panel electrode according to claim 1, which is disposed in a bent region of the touch panel. The protective film of the touch panel electrode according to the first or second aspect of the invention, wherein the minimum value of the light transmittance in the range of 400 nm to 700 nm is 90% or more. The protective film of the touch panel electrode according to any one of claims 1 to 3, which has a thickness of 50 μm or less. A touch panel comprising: a substrate; an electrode disposed on the substrate; and a protective film according to any one of claims 1 to 4, which is disposed on the electrode.