WO2013084284A1 - Method for forming protective film for touch panel electrodes, photosensitive resin composition, and photosensitive element - Google Patents

Abstract

This method for forming a protective film for touch panel electrodes is characterized by comprising: a first step wherein a photosensitive layer, which is formed from a photosensitive resin composition that contains a binder polymer, a photopolymerizable compound and a photopolymerization initiator, is formed on a base that has a touch panel electrode; a second step wherein a predetermined part of the photosensitive layer is cured by irradiation of an active light ray; and a third step wherein a protective film, which covers a part or the whole of the electrode, has a thickness of 10 μm or less, and is formed of a cured product of the photosensitive resin composition, is formed by removing parts of the photosensitive layer other than the predetermined part. This method for forming a protective film for touch panel electrodes is also characterized in that the total solid content of the photosensitive resin composition has a hydroxyl number of 40 mgKOH/g or less.

Description

Method for forming protective film of electrode for touch panel, photosensitive resin composition, and photosensitive element

The present invention relates to a method for forming a protective film for an electrode for a touch panel, and particularly relates to a method for forming a protective film suitable for protecting an electrode of a capacitive touch panel, and a photosensitive resin composition and a photosensitive element used therefor.

Liquid crystal display elements and touch panels (touch sensors) are used in large electronic devices such as personal computers and televisions, small electronic devices such as car navigation systems, mobile phones, and electronic dictionaries, and display devices such as OA / FA devices. These liquid crystal display elements and touch panels are provided with electrodes made of a transparent conductive electrode material. As the transparent conductive electrode material, ITO (Indium-Tin-Oxide), indium oxide and tin oxide are known, and these materials exhibit high visible light transmittance, so that they can be used as electrode materials for substrates for liquid crystal display elements. It has become mainstream.

Various types of touch panels have already been put to practical use, but in recent years, the use of capacitive touch panels has progressed. In a capacitive touch panel, when a fingertip (conductor) contacts the touch input surface, the fingertip and the conductive film are capacitively coupled to form a capacitor. For this reason, the capacitive touch panel detects the coordinates by capturing the change in charge at the contact position of the fingertip.

In particular, the projected capacitive touch panel can detect multiple fingertips, so it has a good operability to give complex instructions. Use as an input device on a display surface in a device having a small display device such as a music player is advancing.

In general, in a projected capacitive touch panel, a plurality of X electrodes and a plurality of Y electrodes orthogonal to the X electrodes have a two-layer structure in order to express two-dimensional coordinates based on the X and Y axes. As the electrode, ITO (Indium-Tin-Oxide) is used.

By the way, since the frame area of the touch panel is an area where the touch position cannot be detected, it is an important factor of the product value to reduce the area of the frame area. In order to reduce the frame area, it is necessary to narrow the widths of the bus electrodes and the lead lines. Since the conductivity of ITO is not sufficiently high, generally, a treatment for increasing the conductivity is performed by forming a metal layer such as aluminum / molybdenum or copper on the bus electrode.

However, when the touch panel as described above is contacted with a fingertip, corrosive components such as moisture and salt may enter the inside from the sensing region. When corrosive components enter the inside of the touch panel, the metal wiring corrodes, and there is a risk of an increase in electrical resistance between the electrode and the driving circuit, or disconnection.

In order to prevent corrosion of metal wiring, a capacitive projection type touch panel in which an insulating layer is formed on metal is disclosed (for example, Patent Document 1). In this touch panel, a silicon dioxide layer is formed on a metal by a plasma chemical vapor deposition method (plasma CVD method) to prevent corrosion of the metal. However, since this method uses a plasma CVD method, there is a problem that a high temperature treatment is required and the base material is limited. There is also a problem that the manufacturing cost becomes high.

As a method of providing a resist film at a necessary location, a method is known in which a photosensitive layer made of a photosensitive resin composition is provided on a predetermined substrate, and this photosensitive layer is exposed and developed (for example, Patent Documents 2 to 4). 3).

JP 2011-28594 A JP-A-7-253666 JP 2005-99647 A Japanese Patent Laid-Open No. 11-133617

Production of a protective film with a photosensitive resin composition can be expected to reduce costs compared to the plasma CVD method. However, when the resin film is formed on the electrode for the touch panel, if the thickness of the resin film is large, a step may be conspicuous between a place where the film is present and a place where the film is not present. Therefore, it is desirable to make the protective film as thin as possible. However, there was no example in which the rust prevention property of the film formed from the photosensitive resin composition was studied at a level of 10 μm or less.

The present invention relates to a method for forming a protective film for a touch panel electrode, which can form a protective film having sufficient anti-rust properties even on a thin film on a predetermined touch panel electrode, and such a protective film. It aims at providing the photosensitive resin composition and photosensitive element which can be formed.

In order to solve the above problems, the present inventors have intensively studied, and as a result, by adjusting the hydroxyl value of the photosensitive resin composition containing a binder polymer, a photopolymerizable compound, and a photopolymerization initiator, developability is improved. While ensuring, even if the film | membrane formed by photocuring was 10 micrometers or less in thickness, it showed sufficient salt-water resistance, discovered that corrosion, such as copper, could fully be prevented, and came to complete this invention.

In the present invention, as a first aspect, a photosensitive layer comprising a photosensitive resin composition containing a binder polymer, a photopolymerizable compound, and a photopolymerization initiator is provided on a substrate having a touch panel electrode. The first step, the second step of curing a predetermined portion of the photosensitive layer by irradiation with actinic rays, and removing the photosensitive layer other than the predetermined portion to cover a part or all of the electrode with a thickness of 10 μm or less. Forming a protective film made of a cured product of the photosensitive resin composition, and forming a protective film for a touch panel electrode having a hydroxyl value of 40 mgKOH / g or less in the entire solid content of the photosensitive resin composition Provide a method.

In this specification, the electrode for the touch panel includes not only electrodes in the sensing area of the touch panel but also metal wiring in the frame area. Either or both of the electrodes provided with the protective layer may be provided.

According to the method for forming a protective film for a touch panel electrode according to the first aspect of the present invention, by using the specific photosensitive resin composition, 10 μm while ensuring developability and adhesion to a substrate. A protective film having a sufficient antirust property can be formed with the following thickness. According to the present invention, it is possible to form a protective film having both sufficient appearance and rust prevention property using the photosensitive resin composition, and thus it is possible to reduce the manufacturing cost in manufacturing the touch panel.

In the first aspect, the binder polymer component preferably has a hydroxyl value of 50 mgKOH / g or less.

In the first aspect, it is preferable that the hydroxyl value of the photopolymerizable compound component is 90 mgKOH / g or less from the viewpoint of further improving the rust prevention property of the protective film.

In addition, from the viewpoint of achieving both adhesion and rust prevention, it is preferable that the photosensitive resin composition further contains a phosphate ester containing a photopolymerizable unsaturated bond.

Furthermore, from the viewpoint of further improving the rust prevention property of the protective film, the acid value of the binder polymer component is preferably 120 mgKOH / g or less.

From the viewpoint of sufficiently ensuring the visibility of the touch panel, the photosensitive layer preferably has a visible light transmittance of 90% or more. In this case, it is suitable for forming a protective film that covers the electrodes in the sensing region.

Further, from the viewpoint of further improving the visibility of the touch panel, the photosensitive layer preferably has a b ^* in the CIELAB color system of −0.2 to 1.0. In this case, it is suitable for forming a protective film that covers the electrodes in the sensing region.

Furthermore, from the viewpoint of further improving developability, the photosensitive resin composition preferably further contains one or more compounds selected from the group consisting of triazole compounds having amino groups and tetrazole compounds having amino groups. . In this case, development residues can be reduced, and it becomes easy to form a protective film with a good pattern.

By the way, it is desirable that the transparency of the protective film is higher considering the visibility and appearance of the touch panel. However, on the other hand, the present inventors have found that when patterning a thin photosensitive layer having high transparency, the resolution tends to decrease. The present inventors consider that the reason is that when the thickness of the photosensitive layer is reduced, it is easily affected by light scattering from the base material and halation occurs.

In conventional photosensitive resin compositions, it is difficult to ensure transparency because the photosensitive properties are controlled by pigments and dyes.

On the other hand, in the present invention, the photopolymerization initiator contains an oxime ester compound or a phosphine oxide compound, whereby a pattern can be formed with sufficient resolution.

The reason why the above effect is obtained is that the oxime moiety contained in the oxime ester compound or the phosphine oxide moiety contained in the phosphine oxide compound has a relatively high photodecomposition efficiency but does not decompose with slight light leakage. The present inventors infer that the influence of leakage light is suppressed because of having a threshold value.

In the first aspect of the present invention, a photosensitive element comprising a support film and a photosensitive layer made of the photosensitive resin composition provided on the support film is prepared, and the photosensitive element The photosensitive layer can be provided by transferring the photosensitive layer onto the substrate. In this case, by using the photosensitive element, a roll-to-roll process can be easily realized, and the solvent drying process can be shortened, which can greatly contribute to shortening of the manufacturing process and cost reduction.

The present invention also provides, as a second aspect, a photosensitive resin composition containing a binder polymer, a photopolymerizable compound, and a photopolymerization initiator, wherein the hydroxyl groups in the entire solid content of the photosensitive resin composition Provided is a photosensitive resin composition used for forming a protective film for a touch panel electrode having a value of 40 mgKOH / g or less.

According to the photosensitive resin composition according to the second aspect of the present invention, a protective film having sufficient rust resistance can be formed on a predetermined touch panel electrode even if it is a thin film.

In the second aspect, the binder polymer component preferably has a hydroxyl value of 50 mgKOH / g or less.

In the second aspect, the hydroxyl value of the photopolymerizable compound component is preferably 90 mgKOH / g or less from the viewpoint of further improving the rust prevention property of the protective film.

Further, from the viewpoint of achieving both adhesion and developability, the photosensitive resin composition according to the second aspect of the present invention preferably further contains a phosphate ester containing a photopolymerizable unsaturated bond.

Furthermore, from the viewpoint of further improving the rust prevention property of the protective film, the acid value of the binder polymer component is preferably 120 mgKOH / g or less.

From the viewpoint of sufficiently ensuring the visibility of the touch panel, the photosensitive resin composition according to the second aspect of the present invention preferably has a visible light transmittance of 90% or more when a film having a thickness of 5 μm is formed. .

Further, from the viewpoint of further improving the visibility of the touch panel, the photosensitive resin composition according to the second aspect of the present invention has a b ^* in the CIELAB color system of −0. It is preferably 2 to 1.0.

From the viewpoint of further improving developability, the photosensitive resin composition according to the second aspect of the present invention comprises one or more compounds selected from the group consisting of triazole compounds having amino groups and tetrazole compounds having amino groups. Furthermore, it is preferable to contain. In this case, development residues can be reduced, and it becomes easy to form a protective film with a good pattern.

In the photosensitive resin composition according to the second aspect of the present invention, it is preferable that the photopolymerization initiator contains an oxime ester compound or a phosphine oxide compound. In this case, it is possible to form a thin protective layer having a high resolution and a pattern having a sufficient resolution.

The present invention also provides, as a third aspect, a photosensitive element comprising a support film, and a photosensitive layer comprising the photosensitive resin composition according to the second aspect of the present invention provided on the support film. provide.

According to the photosensitive element of the third aspect of the present invention, a protective film having sufficient rust prevention can be formed on a predetermined touch panel electrode even if it is a thin film.

The thickness of the photosensitive layer can be 10 μm or less.

As a fourth aspect of the present invention, a protective film that covers a part or all of the electrode is formed on a substrate having a touch panel electrode by the method for forming a protective film according to the first aspect of the present invention. The manufacturing method of a touch panel sensor provided with the process to perform is provided.

ADVANTAGE OF THE INVENTION According to this invention, the protective film formation method of the electrode for touchscreens which can form the protective film which has sufficient antirust property even if it is a thin film on the electrode for predetermined touchscreens, and such protection A photosensitive resin composition and a photosensitive element that can form a film can be provided.

Moreover, according to the present invention, the metal electrode of the capacitive touch panel can be protected. Furthermore, according to the present invention, it is possible to protect the electrodes in the frame region of the touch panel in which a metal layer such as copper, which is easily rusted by moisture or salt, is formed to improve conductivity.

It is a schematic cross section which shows one Embodiment of the photosensitive element of this invention. It is a schematic cross section for demonstrating one Embodiment of the formation method of the protective film of the electrode for touchscreens of this invention.

Hereinafter, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In this specification, (meth) acrylic acid means acrylic acid or methacrylic acid, (meth) acrylate means acrylate or methacrylate, and (meth) acryloyl group means acryloyl group or methacryloyl. Means group. The (poly) oxyethylene chain means an oxyethylene group or a polyoxyethylene group, and the (poly) oxypropylene chain means an oxypropylene group or a polyoxypropylene group. Further, “(EO) modified” means a compound having a (poly) oxyethylene chain, and “(PO) modified” means a compound having a (poly) oxypropylene chain. “(EO) · (PO) modified” means a compound having both a (poly) oxyethylene chain and a (poly) oxypropylene chain.

In addition, in this specification, the term “process” is not limited to an independent process, and even if it cannot be clearly distinguished from other processes, the term “process” is used as long as the intended action of the process is achieved. included. In the present specification, a numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.

Further, in the present specification, the content of each component in the composition is the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition. Means.

FIG. 1 is a schematic cross-sectional view showing an embodiment of the photosensitive element of the present invention. A photosensitive element 1 shown in FIG. 1 includes a support film 10, a photosensitive layer 20 made of the photosensitive resin composition according to the present invention provided on the support film, and the opposite side of the photosensitive layer 20 from the support film 10. And a protective film 30 provided on the surface.

The photosensitive element of the present embodiment can be suitably used for forming a protective film for a touch panel electrode.

Examples of the support film 10 include films having a thickness of about 5 to 100 μm made of polyethylene terephthalate, polycarbonate, polyethylene, polypropylene, polyethersulfone, and the like.

The thickness of the support film is preferably from 5 to 100 μm, more preferably from 10 to 70 μm, from the viewpoints of ensuring coverage and suppressing a decrease in resolution during exposure through the support film.

An embodiment of the photosensitive resin composition according to the present invention constituting the photosensitive layer 20 includes a binder polymer (hereinafter also referred to as (A) component), a photopolymerizable compound (hereinafter also referred to as (B) component), A photopolymerization initiator (hereinafter also referred to as “component (C)”), and the hydroxyl value of the entire solid content of the photosensitive resin composition is 40 mgKOH / g or less.

The hydroxyl value of the whole solid content of the photosensitive resin composition can be measured as follows. That is, first, 1 g of the photosensitive resin composition whose hydroxyl value is to be measured is precisely weighed. If the photosensitive resin composition contains a volatile component such as a synthetic solvent or a diluent solvent, the photosensitive resin composition is previously heated at a temperature about 10 ° C. higher than the boiling point of the volatile component for 1 to 4 hours to remove the volatile component. deep. 10 mL of a 10% by mass acetic anhydride pyridine solution is added to the precisely weighed photosensitive resin composition to dissolve it uniformly, and heated at 100 ° C. for 1 hour. After heating, 10 mL of water and 10 mL of pyridine are added and heated at 100 ° C. for 10 minutes. Thereafter, it can be measured by neutralization titration with an ethanol solution of 0.5 mol / L potassium hydroxide using an automatic titrator (“COM-1700” manufactured by Hiranuma Sangyo Co., Ltd.).
The hydroxyl value can be calculated by the following formula.
Hydroxyl value = (AB) × f × 28.05 / sample (g) + acid value In the formula, A represents the amount (ml) of 0.5 mol / l potassium hydroxide ethanol solution used for the blank test, B represents the amount (ml) of 0.5 mol / l potassium hydroxide ethanol solution used for titration, and f represents a factor.

Further, the hydroxyl value of the entire solid content of the photosensitive layer in the photosensitive element described later can be measured as follows. That is, first, a photosensitive resin composition is formed by laminating a photosensitive element on a glass substrate a plurality of times, superimposing only the photosensitive layer of the photosensitive element, and then forming a photosensitive layer whose hydroxyl value should be measured with a metal spatula. As a kakio, weigh exactly 1 g. The precisely weighed photosensitive resin composition is transferred to an Erlenmeyer flask, 10 mL of 10% by mass acetic anhydride pyridine solution is added to dissolve it uniformly, and heated at 100 ° C. for 1 hour. After heating, 10 mL of water and 10 mL of pyridine are added and heated at 100 ° C. for 10 minutes. Thereafter, it can be measured by neutralization titration with an ethanol solution of 0.5 mol / L potassium hydroxide using an automatic titrator (“COM-1700” manufactured by Hiranuma Sangyo Co., Ltd.).

The hydroxyl value of the component (A) can be obtained by accurately weighing 1 g of the binder polymer whose hydroxyl value is to be measured, and then measuring the binder polymer in the same manner as the above-described measurement of the hydroxyl value. When the binder polymer contains a volatile component such as a synthetic solvent or a diluting solvent, the binder polymer is previously heated at a temperature about 10 ° C. higher than the boiling point of the volatile component for 1 to 4 hours to remove the volatile component.

By setting the hydroxyl value of the entire solid content of the photosensitive resin composition within the above range, a protective film having a sufficient antirust property can be formed with a thickness of 10 μm or less.

The present inventors infer the reason why the above effect is obtained as follows. When a thin film having a thickness of 10 μm or less is formed using the photosensitive resin composition, corrosive components such as moisture and salt are likely to be included in the film, and this tendency is caused by hydroxyl groups contained in the photosensitive resin composition, particularly hydroxy groups. The present inventors consider that the size is further increased by the alkyl group. In the present embodiment, the entire solid content of the photosensitive resin composition, that is, the hydroxyl value of the entire component forming the protective film is within the above range, so that the reduction in rust prevention due to hydroxyl groups can be sufficiently suppressed. Conceivable.

As the binder polymer as the component (A), any polymer can be used without particular limitation as long as the hydroxyl value of the entire solid content of the photosensitive resin composition is adjusted to 40 mgKOH / g or less. In view of the excellent antirust property of the protective film, the hydroxyl value of the component (A) is preferably 50 mgKOH / g or less, and more preferably 45 mgKOH / g or less.

As the component (A), for example, a polymer having a carboxyl group can be used.

In the present embodiment, the component (A) is preferably a copolymer containing structural units derived from (a) (meth) acrylic acid and (b) (meth) acrylic acid alkyl ester.

Examples of the (meth) acrylic acid alkyl ester include (meth) acrylic acid methyl ester, (meth) acrylic acid ethyl ester, (meth) acrylic acid butyl ester, (meth) acrylic acid 2-ethylhexyl ester, and (meth) acrylic acid ester. ) Acrylic acid hydroxyl ethyl ester.

When a (meth) acrylic acid alkyl ester containing a hydroxyl group, such as the above (meth) acrylic acid hydroxyl ethyl ester, is preferably adjusted so that the hydroxyl value of the component (A) is 50 mgKOH / g or less. It is more preferable to adjust so that it may become 45 mgKOH / g or less.

The copolymer may further contain other monomers that can be copolymerized with the components (a) and (b) as constituent units.

Examples of other monomers that can be copolymerized with the components (a) and (b) include (meth) acrylic acid tetrahydrofurfuryl ester, (meth) acrylic acid dimethylaminoethyl ester, and (meth) acrylic acid diethylamino acid. Ethyl ester, (meth) acrylic acid glycidyl ester, (meth) acrylic acid benzyl ester, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, acrylamide Acrylonitrile, diacetone acrylamide, styrene, and vinyl toluene. When synthesizing the binder polymer as component (A), the above monomers may be used alone or in combination of two or more.

The molecular weight of the binder polymer as component (A) is not particularly limited, but from the viewpoint of coating properties, coating film strength, and developability, it is usually a weight average molecular weight (a value measured in terms of standard polystyrene using GPC). ) Is preferably 10,000 to 200,000, more preferably 30,000 to 150,000, and most preferably 50,000 to 100,000. In addition, the measurement conditions of a weight average molecular weight shall be the same measurement conditions as the Example of this-application specification.

The acid value of the binder polymer as the component (A) can be developed with various known developing solutions in the step of selectively removing the photosensitive resin composition layer in the development step, From the viewpoint of improving resistance to corrosive components such as moisture and salt when functioning as a protective film, it is preferably 120 mgKOH / g or less.

For example, when developing with an aqueous alkali solution such as sodium carbonate, potassium carbonate, tetramethylammonium hydroxide, triethanolamine, etc., the acid value is preferably 50 to 120 mgKOH / g. In terms of excellent developability, it is preferably 50 mgKOH / g or more. When protecting the touch panel electrode, from the viewpoint of protecting the electrode from corrosive components such as moisture and salt, it is preferably 120 mgKOH / g or less. .

Further, by setting the acid value of the binder polymer to 16 to 120 mgKOH / g, development can be performed using an alkaline aqueous solution containing water, an alkali metal salt, and a surfactant. If the acid value is less than 16 mgKOH / g, development tends to be difficult, and if it exceeds 120 mgKOH / g, the electrode tends to be unable to be protected for the reasons described above.

The photopolymerizable compound as component (B) can be substituted without particular limitation depending on the required properties, provided that the hydroxyl value of the entire solid content of the photosensitive resin composition is 40 mgKOH / g or less. However, the hydroxyl value of the component (B) is preferably 90 mgKOH / g or less, and more preferably 60 mgKOH / g or less.

The hydroxyl value of the component (B) is measured in the same manner as the measurement of the hydroxyl value of the photopolymerizable compound solution after precisely weighing about 1 g of the solution of the photopolymerizable compound whose hydroxyl value is to be measured. Is required. If the photopolymerizable compound contains a volatile component such as a synthetic solvent or a diluting solvent, the volatile component is previously removed by heating at a temperature about 10 ° C. higher than the boiling point of the volatile component for 1 to 4 hours. .

As the photopolymerizable compound as component (B), a photopolymerizable compound having an ethylenically unsaturated group can be used.

Examples of the photopolymerizable compound having an ethylenically unsaturated group include a monofunctional vinyl monomer, a bifunctional vinyl monomer, and a polyfunctional vinyl monomer having at least three polymerizable ethylenically unsaturated groups.

Examples of the monofunctional vinyl monomer include (meth) acrylic acid, (meth) acrylic acid alkyl ester, and those co-polymerized as monomers used for the synthesis of a copolymer which is a preferred example of the component (A). Examples thereof include polymerizable monomers.

Examples of the bifunctional vinyl monomer include polyethylene glycol di (meth) acrylate (having 2 to 14 ethoxy groups), trimethylolpropane di (meth) acrylate, polypropylene glycol di (meth) acrylate (propylene group Bisphenol A polyoxyethylene di (meth) acrylate (2,2-bis (4- (meth) acryloxypolyethoxyphenyl) propane), bisphenol A diglycidyl ether di (meth) acrylate And the like; and esterified products of polyvalent carboxylic acids (such as phthalic anhydride) and substances having a hydroxyl group and an ethylenically unsaturated group (such as β-hydroxyethyl acrylate and β-hydroxyethyl methacrylate). Examples of the bisphenol A polyoxyethylene dimethacrylate include bisphenol A dioxyethylene diacrylate, bisphenol A dioxyethylene dimethacrylate, bisphenol A trioxyethylene diacrylate, bisphenol A trioxyethylene dimethacrylate, and bisphenol A pentaoxy. Examples include ethylene diacrylate, bisphenol A pentaoxyethylene dimethacrylate, bisphenol A deoxyoxyethylene diacrylate, and bisphenol A deoxyoxyethylene dimethacrylate.

Examples of the polyfunctional vinyl monomer having at least three polymerizable ethylenically unsaturated groups include trimethylolpropane tri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, Compounds obtained by reacting α, β-unsaturated saturated carboxylic acids with polyhydric alcohols such as dipentaerythritol penta (meth) acrylate and dipentaerythritol hexa (meth) acrylate; trimethylolpropane triglycidyl ether triacrylate and the like Examples thereof include compounds obtained by adding an α, β-unsaturated carboxylic acid to a glycidyl group-containing compound.

Among these, it is preferable to contain a polyfunctional vinyl monomer having at least three polymerizable ethylenically unsaturated groups. Furthermore, from the viewpoint of electrode corrosion inhibition and ease of development, it has a (meth) acrylate compound having a skeleton derived from pentaerythritol, a (meth) acrylate compound having a skeleton derived from dipentaerythritol, and a skeleton derived from trimethylolpropane. It is preferable to include at least one selected from (meth) acrylate compounds, and at least selected from (meth) acrylate compounds having a skeleton derived from dipentaerythritol and (meth) acrylate compounds having a skeleton derived from trimethylolpropane. It is more preferable that 1 type is included.

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

The (meth) acrylate compound having a skeleton derived from trimethylolpropane means an esterified product of trimethylolpropane and (meth) acrylic acid, and the esterified product is modified with an alkyleneoxy group. Also included are compounds. In the above esterified product, the number of ester bonds in one molecule is preferably 3, but a compound having 1 to 2 ester bonds may be mixed.

The above compounds can be used alone or in combination of two or more.

When a monomer having at least three polymerizable ethylenically unsaturated groups in the molecule is used in combination with a monofunctional vinyl monomer or a bifunctional vinyl monomer, the ratio to be used is not particularly limited, but photocurability and electrode corrosion From the viewpoint of obtaining an inhibitory power, the proportion of the monomer having at least three polymerizable ethylenically unsaturated groups in the molecule is 100 parts by mass of the total amount of the photopolymerizable compounds contained in the photosensitive resin composition. , Preferably 30 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 75 parts by mass or more.

The content of the component (A) and the component (B) in the photosensitive resin composition of the present embodiment is such that the amount of the component (A) is 40 to 80 with respect to 100 parts by mass of the total amount of the components (A) and (B). The component (B) is preferably 20 to 60 parts by mass, the component (A) is preferably 50 to 70 parts by mass, and the component (B) is more preferably 30 to 50 parts by mass. More preferably, the component is 55 to 65 parts by mass and the component (B) is 35 to 45 parts by mass.

By setting the content of the component (A) within the above range, sufficient sensitivity can be obtained while sufficiently ensuring the coatability or film properties of the photosensitive element, and photocurability, developability, and electrode corrosion. Can be sufficiently secured.

Examples of the photopolymerization initiator as component (C) include benzophenone, N, N′-tetramethyl-4,4′-diaminobenzophenone (Michler ketone), N, N′-tetraethyl-4,4′-diaminobenzophenone. 4-methoxy-4′-dimethylaminobenzophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2-methyl-1- [4- (methylthio) phenyl] -2 An aromatic ketone such as morpholino-propanone-1, 2-ethylanthraquinone, phenanthrenequinone, 2-tert-butylanthraquinone, octamethylanthraquinone, 1,2-benzanthraquinone, 2,3-benzanthraquinone, 2-phenylanthraquinone, 2,3-diphenylanthraquinone, 1-c Quinones such as loanthraquinone, 2-methylanthraquinone, 1,4-naphthoquinone, 9,10-phenantharaquinone, 2-methyl-1,4-naphthoquinone, 2,3-dimethylanthraquinone; benzoin methyl ether, benzoin ethyl ether, Benzoin ether compounds such as benzoin phenyl ether, benzoin compounds such as benzoin, methylbenzoin, and ethylbenzoin; 1.2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)], ethanone, Oxime ester compounds such as 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-and 1- (0-acetyloxime); benzyl derivatives such as benzyldimethyl ketal; (O-chlorophenyl) -4,5- Phenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di (methoxyphenyl) imidazole dimer, 2- (o-fluorophenyl) -4,5-diphenylimidazole dimer, 2- ( 2,4,5-triarylimidazole dimer such as o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methoxyphenyl) -4,5-diphenylimidazole dimer; 9 -Acridine derivatives such as -phenylacridine and 1,7-bis (9,9'-acridinyl) heptane; N-phenylglycine, N-phenylglycine derivatives, coumarin compounds and oxazole compounds. Further, the substituents of the aryl groups of two 2,4,5-triarylimidazoles may be the same to give the target compound, or differently give an asymmetric compound. Moreover, you may combine a thioxanthone type compound and a tertiary amine compound like the combination of diethyl thioxanthone and dimethylaminobenzoic acid.

Among these, an oxime ester compound or a phosphine oxide compound is preferable from the transparency of the protective film to be formed and the pattern forming ability when the film thickness is 10 μm or less. Examples of the oxime ester compound include compounds represented by the following general formula (C-1) and general formula (C-2). From the viewpoint of fast curability and transparency, the following general formula (C-1) The compound represented by these is preferable.

 

In the general formula (C-1), R ¹ is an alkyl group having 1 to 12 carbon atoms, an organic group containing a cycloalkyl group having 3 to 20 carbon atoms, an alkanoyl group having 2 to 12 carbon atoms, or a double bond. An alkenoyl group having 4 to 6 carbon atoms, a benzoyl group, an alkoxycarbonyl group having 2 to 6 carbon atoms or a phenoxycarbonyl group which is not conjugated with a carbonyl group is shown. In addition, as long as the effect of the present invention is not inhibited, the aromatic ring in the general formula (C-1) may have a substituent.

In the above general formula (C-1), R ¹ is preferably an organic group containing an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 3 to 20 carbon atoms, and an alkyl group having 3 to 10 carbon atoms. Or an organic group containing a cycloalkyl group having 4 to 15 carbon atoms, particularly an organic group containing an alkyl group having 4 to 8 carbon atoms or a cycloalkyl group having 4 to 10 carbon atoms. preferable.

 

In the general formula (C-2), R ² represents a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyclopentyl group, a cyclohexyl group, a phenyl group, a benzyl group, a benzoyl group, an alkanoyl group having 2 to 12 carbon atoms, Represents an alkoxycarbonyl group or phenoxycarbonyl group having 2 to 12 carbon atoms, R ³ represents an organic group containing an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 3 to 20 carbon atoms, and R ⁴ is independently selected. A halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyclopentyl group, a cyclohexyl group, a phenyl group, a benzyl group, a benzoyl group, an alkanoyl group having 2 to 12 carbon atoms, an alkoxycarbonyl group having 2 to 12 carbon atoms, or phenoxy Represents a carbonyl group, R ⁵ represents an alkyl group having 2 to 20 carbon atoms or an arylene group, and p1 represents an integer of 0 to 3 The When p1 is 2 or more, a plurality of R ⁴ may be the same or different. Note that carbazole may have a substituent as long as the effects of the present invention are not impaired.

In the general formula (C-2), R ² is preferably an alkyl group having 1 to 12 carbon atoms, more preferably an alkyl group having 1 to 8 carbon atoms, and an alkyl group having 1 to 4 carbon atoms. It is particularly preferred that

In the general formula (C-2), R ³ is preferably an organic group containing an alkyl group having 1 to 8 carbon atoms and a cycloalkyl group having 4 to 15 carbon atoms, an alkyl group having 1 to 4 carbon atoms, A cycloalkyl group having 4 to 10 carbon atoms is more preferable.

Examples of the compound represented by the general formula (C-1) and the compound represented by the general formula (C-2) include 1,2-octanedione, 1- [4- (phenylthio)-, 2- (O -Benzoyloxime)], ethanone, 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime) and the like. 1,2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)] is EGANONE, 1- [IRGACURE-OXE01 (trade name, manufactured by Ciba Specialty Chemicals). 9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl]-, 1- (O-acetyloxime) is commercially available as IRGACURE-OXE02 (trade name, manufactured by Ciba Specialty Chemicals) Are available. These are used alone or in combination of two or more.

Of the above general formula (C-1), 1,2-octanedione, 1- [4- (phenylthio)-, 2- (O-benzoyloxime)] is particularly preferable.

Examples of the phosphine oxide compound include compounds represented by the following general formula (C-3) and general formula (C-4). From the viewpoint of fast curability and transparency, a compound represented by the following general formula (C-3) is preferred.

 

In the general formula (C-3), R ⁶ , R ⁷ and R ⁸ each independently represents an alkyl group or aryl group having 1 to 20 carbon atoms. In general formula (C-4), R ⁹ , R ¹⁰ and R ¹¹ each independently represents an alkyl group or aryl group having 1 to 20 carbon atoms.

When R ⁶ , R ⁷ or R ⁸ in the general formula (C-3) is an alkyl group having 1 to 20 carbon atoms, the alkyl group may be linear, branched, or cyclic In addition, the alkyl group preferably has 5 to 10 carbon atoms. When R ⁹ , R ¹⁰ or R ¹¹ in the general formula (C-4) is an alkyl group having 1 to 20 carbon atoms, the alkyl group may be linear, branched, or cyclic Further, the alkyl group preferably has 5 to 10 carbon atoms.

When R ⁶ , R ⁷ or R ⁸ in the general formula (C-3) is an aryl group, the aryl group may have a substituent. Examples of the substituent include an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 4 carbon atoms. When R ⁹ , R ¹⁰ or R ¹¹ in the general formula (C-4) is an aryl group, the aryl group may have a substituent. Examples of the substituent include an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 4 carbon atoms.

Among these, in general formula (C-3), R ⁶ , R ⁷ , and R ⁸ are preferably aryl groups, and the compounds represented by general formula (C-4) are represented by R ⁹ , R ¹⁰ And R ¹¹ is preferably an aryl group.

The compound represented by the general formula (C-3) includes 2,4,6-trimethylbenzoyl-diphenyl-phosphine because of the transparency of the protective film to be formed and the pattern forming ability when the film thickness is 10 μm or less. Oxides are preferred. 2,4,6-Trimethylbenzoyl-diphenyl-phosphine oxide is commercially available, for example, as DAROCUR-TPO (trade name, manufactured by BASF Japan).

The content of the photopolymerization initiator as component (C) is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the total amount of components (A) and (B), and 1 to 10 parts by mass. Part is more preferable, and 2 to 5 parts by mass is even more preferable.

By making the content of the component (C) within the above range, the photosensitivity is sufficient, and the absorption on the surface of the composition is increased at the time of exposure, and the internal photocuring becomes insufficient. Problems such as a reduction in visible light transmittance can be suppressed.

The photosensitive resin composition of this embodiment is one or more compounds selected from the group consisting of a triazole compound having an amino group and a tetrazole compound having an amino group from the viewpoint of suppressing the occurrence of development residue on the metal surface to be removed ( Hereinafter, it is preferable to further contain (D) component).

Examples of the triazole compound having an amino group include benzotriazole, 1H-benzotriazole-1-acetonitrile, benzotriazole-5-carboxylic acid, 1H-benzotriazole-1-methanol, carboxybenzotriazole, etc. , 3-mercaptotriazole, 5-mercaptotriazole, and other triazole compounds containing a mercapto group are substituted with amino groups. Among these, from the viewpoint of further reducing the development residue, it is preferable to include a compound in which an amino group is substituted for a triazole compound containing a mercapto group.

Examples of the tetrazole compound having an amino group include compounds represented by the following general formula (D-1).

R ¹¹ and R ¹² in the general formula (D-1) are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a phenyl group, an aminophenyl group, carbon An alkylphenyl group having 7 to 20 amino acids, a mercapto group, an alkylmercapto group having 1 to 10 carbon atoms or a carboxyalkyl group having 2 to 10 carbon atoms, wherein at least one of R ¹¹ and R ¹² represents an amino group; Have.

Alkyl groups include methyl, ethyl, propyl, iso-propyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl Group, tridecyl group, tetradecyl group, pentadecyl group, octadecyl group, nonadecyl group, icosyl group and the like.

Examples of the cycloalkyl group include a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. Examples of the alkylphenyl group include a methylphenyl group and an ethylphenyl group.

Examples of the alkyl mercapto group include a methyl mercapto group and an ethyl mercapto group. Examples of the carboxyalkyl group include a carboxymethyl group and a carboxyethyl group.

Among the tetrazole compounds represented by the general formula (D-1), 5-amino-1H-tetrazole, 1-methyl-5-amino-tetrazole, 1-methyl-5-mercapto-tetrazole, 5- (2- Aminophenyl) -1H-tetrazole, 1-cyclohexyl-5-amino-tetrazole, 1-phenyl-5-amino-tetrazole, 1-carboxymethyl-5-amino-tetrazole are preferred.

The tetrazole compound represented by the general formula (D-1) is preferably a water-soluble salt thereof. Specific examples include alkali metal salts of 1-methyl-5-amino-tetrazole such as sodium, potassium and lithium.

Of these, 5-amino-1H-tetrazole and 1-methyl-5-mercapto-1H-tetrazole are particularly preferred from the viewpoints of the ability to suppress electrode corrosion, adhesion to metal electrodes, ease of development, and transparency.

These tetrazole compounds and water-soluble salts thereof may be used singly or in combination of two or more.

In addition, from the viewpoint of further improving developability when the electrode surface on which the protective layer is provided has a metal such as copper, copper alloy, nickel alloy, the photosensitive resin composition is a tetrazole compound or mercapto group having an amino group. It is preferable to further contain a compound in which an amino group is substituted for a triazole compound containing. In this case, development residues can be reduced, and it becomes easy to form a protective film with a good pattern. As this reason, it is thought that moderate adhesion of the surface is expressed.

When a tetrazole compound having an amino group or a triazole compound containing a mercapto group contains a compound in which an amino group is substituted, the above effect is obtained. Therefore, the photosensitive resin composition and the photosensitive element according to this embodiment are It is suitable for forming a protective film for protecting an electrode in a frame region of a touch panel in which a metal layer such as copper is formed to improve conductivity.

The content of the component (D) in the photosensitive resin composition of the present embodiment is 0.05 to 10.0 parts by mass with respect to 100 parts by mass of the total amount of the components (A) and (B). Preferably, the amount is 0.1 to 2.0 parts by mass, and more preferably 0.2 to 1.0 part by mass.

(D) By making content of a component into the said range, the effect which improves the inhibitory force of electrode corrosion and adhesiveness with a metal electrode is fully suppressed, suppressing malfunction, such as a developability and a resolution. Obtainable.

By the way, when providing a protective layer on a part of the ITO electrode of the touch panel, for example, a part where a protective layer is not formed in the view area, but a metal layer such as copper is formed on the ITO electrode in the frame region and the ITO electrode. When a protective layer is provided, unnecessary portions can be removed by exposure and development after the photosensitive layer is provided on the entire surface. In this case, the photosensitive layer is required to have good developability so as not to cause development residue in unnecessary portions while having sufficient adhesion to the electrode to be protected. From the viewpoint of achieving both adhesion and developability in such a case, the photosensitive resin composition of the present embodiment contains a phosphate ester (hereinafter also referred to as component (E)) containing a photopolymerizable unsaturated bond. It is preferable to contain.

It is preferable to use a compound having the following structure as the phosphate ester from the viewpoint of achieving both high adhesion and developability to the ITO electrode while ensuring sufficient rust prevention properties of the protective film to be formed. The compound is commercially available such as PM21 (manufactured by Nippon Kayaku Co., Ltd.).

 

In addition, the compounding quantity of phosphate ester is mix | blended so that the hydroxyl value of the whole solid content of the photosensitive resin composition may be 40 mgKOH / g or less in 1st Embodiment. In 2nd Embodiment, it is preferable to mix | blend so that the hydroxyl value of the whole solid content of the photosensitive resin composition may be 40 mgKOH / g or less.

In the photosensitive resin composition of the present embodiment, if necessary, an adhesion imparting agent such as a silane coupling agent, a leveling agent, a plasticizer, a filler, an antifoaming agent, a flame retardant, a stabilizer, and an antioxidant. In addition, a perfume, a thermal crosslinking agent, a polymerization inhibitor and the like can be contained in an amount of about 0.01 to 20 parts by mass with respect to 100 parts by mass of the total amount of component (A) and component (B). These can be used alone or in combination of two or more.

The photosensitive resin composition of the present embodiment preferably has a visible light transmittance of 90% or more, more preferably 92% or more, and even more preferably 95% or more.

Here, the visible light transmittance of the photosensitive resin composition is determined as follows. First, a photosensitive resin composition is applied on a support film so that the thickness after drying is 5 μm, and dried to form a photosensitive resin composition layer. Next, it laminates on a glass substrate using a laminator so that the photosensitive resin composition layer contacts. Thus, a measurement sample in which the photosensitive resin composition layer and the support film are laminated on the glass substrate is obtained. Next, after the photosensitive resin composition layer is photocured by irradiating the obtained measurement sample with ultraviolet rays, the transmittance in a measurement wavelength region of 400 to 700 nm is measured using an ultraviolet-visible spectrophotometer.

Note that the above-described suitable transmittance means the minimum value of the transmittance in the above wavelength range.

If the transmittance in the wavelength range of 400 to 700 nm, which is a light ray in the general visible light wavelength range, is 90% or more, for example, when protecting the transparent electrode of the display part of the touch panel (touch sensor) or touch panel (touch When the protective layer is visible from the edge of the display part when the metal layer (for example, a layer in which a copper layer is formed on the ITO electrode) is protected, the display quality, hue, A decrease in luminance can be sufficiently suppressed.

In the photosensitive resin composition of the present embodiment, from the viewpoint of further improving the visibility of the touch panel, b ^* in the CIELAB color system is preferably −0.2 to 1.0, and −0. It is more preferably 0 to 0.7, and still more preferably 0.1 to 0.4. When b ^* is 0.8 or more or −0.2 or less, the display quality and color tone in the display portion tend to be reduced, as in the case where the visible light transmittance is less than 90%. The measurement of b ^* in the CIELAB color system uses, for example, a spectrocolorimeter “CM-5” manufactured by Konica Minolta, and a glass of 0.7 mm in thickness with b ^* of 0.1 to 0.2. It is obtained by forming a photosensitive resin composition layer having a thickness of 5 μm on a substrate, photo-curing the photosensitive resin composition layer by irradiating ultraviolet rays, and then measuring by setting a D65 light source and a viewing angle of 2 °.

The photosensitive resin composition of the present embodiment is preferably used by forming a film on a photosensitive film like the photosensitive element of the present embodiment. By laminating the photosensitive film on the substrate having the electrode for the tapping panel, a roll-to-roll process can be easily realized, and the solvent drying process can be shortened. it can.

The photosensitive layer 20 can be formed by using the photosensitive resin composition of the present embodiment as a coating solution, and applying and drying the same on a support film. The coating liquid can be obtained by uniformly dissolving or dispersing each component constituting the photosensitive resin composition of the present embodiment described above in a solvent.

The solvent is not particularly limited and known ones can be used. For example, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, methanol, ethanol, propanol, butanol, methylene glycol, ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, Examples include ethylene glycol monoethyl ether, propylene glycol monomethyl ether, chloroform, and methylene chloride. These solvents may be used alone or as a mixed solvent composed of two or more solvents.

Application methods include, for example, doctor blade coating method, Meyer bar coating method, roll coating method, screen coating method, spinner coating method, inkjet coating method, spray coating method, dip coating method, gravure coating method, curtain coating method, die coating Examples thereof include a coating method.

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

The thickness of the photosensitive layer is 10 μm or less after drying so that the step on the surface of the touch panel (touch sensor) caused by the formation of a partial electrode protective film is minimized as much as possible to exert a sufficient effect on electrode protection. Is preferably 2 to 10 μm, more preferably 3 to 8 μm.

In the present embodiment, the photosensitive layer 20 preferably has a visible light transmittance of 90% or more, more preferably 92% or more, and even more preferably 95% or more. The photosensitive layer 20 is preferably adjusted so that b ^* in the CIELAB color system is −0.2 to 1.0.

The viscosity of the photosensitive layer 20 prevents the photosensitive resin composition from oozing out from the end face of the photosensitive element for one month or more when it is used as a photosensitive element for forming a protective film of a roll-shaped touch panel electrode. From 30 to 100 MPa · s at 30 ° C. from the standpoint of preventing exposure failure and residual development caused by the fragments of the photosensitive resin composition adhering to the substrate when the photosensitive element is cut. More preferably, it is ˜90 MPa · s, and even more preferably 25-80 MPa · s.

The viscosity is 1.96 × at 30 ° C. and 80 ° C. in the thickness direction of this sample using a circular film of 7 mm in diameter and 2 mm in thickness formed from the photosensitive resin composition as a measurement sample. This is a value obtained by measuring the rate of change of thickness when a load of 10 ⁻² N is applied, and converting it to viscosity from the rate of change assuming a Newtonian fluid.

Examples of the protective film 30 (cover film) include polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polyethylene-vinyl acetate copolymer, and a laminated film of polyethylene-vinyl acetate copolymer and polyethylene having a thickness of 5 to 100 μm. Degree film.

Photosensitive element 1 can be stored in a roll or stored.

In the present invention, the photosensitive resin composition coating liquid of the present embodiment described above may be applied on a substrate having a touch panel electrode and dried to provide a photosensitive layer made of the photosensitive resin composition. Good. Even in this application, the photosensitive layer preferably satisfies the above-mentioned conditions of film thickness, visible light transmittance, and b ^* in the CIELAB color system.

Next, a method for forming a protective film for an electrode for a touch panel according to the present invention will be described. FIG. 2 is a schematic cross-sectional view for explaining an embodiment of a method for forming a protective film for an electrode for a touch panel according to the present invention.

The method for forming a protective film for a touch panel electrode according to the present embodiment is a first method in which the photosensitive layer 20 made of the photosensitive resin composition according to the present embodiment is provided on the base material 100 having the touch panel electrodes 110 and 120. A step, a second step in which a predetermined portion of the photosensitive layer 20 is cured by irradiation with actinic rays, and a photosensitive layer having a thickness of 10 μm or less covering a part or all of the electrode by removing the photosensitive layer other than the predetermined portion after exposure. And a third step of forming a protective film 22 made of a cured product of the resin composition. In this way, the touch panel sensor 200 with a protective film is obtained.

The substrate used in the present embodiment is not particularly limited, and examples thereof include substrates such as glass plates, plastic plates, and ceramic plates that are generally used for touch panels (touch sensors). On this substrate, a touch panel electrode to be a target for forming a protective film is provided. Examples of the electrode include electrodes such as ITO, Cu, Al, and Mo, and TFT. Further, an insulating layer may be provided over the substrate.

2 can be obtained by the following procedure, for example. After forming a metal film by sputtering in the order of ITO and Cu on a substrate such as a PET film, an etching photosensitive film is pasted on the metal film to form a desired resist pattern, and unnecessary Cu is iron chloride. After removing with an etching solution such as an aqueous solution, the resist pattern is peeled off.

In the first step of this embodiment, after removing the protective film 30 of the photosensitive element 1 of this embodiment, the surface on which the touch panel electrodes 110 and 120 of the substrate 100 are provided while heating the photosensitive element. The photosensitive layer 20 is laminated by pressure bonding (see FIG. 2A).

Crimping means includes a crimping roll. The pressure roll may be provided with a heating means so that it can be heat-pressure bonded.

The heating temperature for thermocompression bonding is preferably 10 to 180 ° C. so that the components of the photosensitive layer are not easily cured or thermally decomposed while ensuring sufficient adhesion between the photosensitive layer and the substrate. More preferably, the temperature is set to ˜160 ° C., and more preferably 30 to 150 ° C.

In addition, the pressure at the time of thermocompression bonding is set to 50 to 1 × 10 ⁵ N / m in terms of linear pressure from the viewpoint of suppressing deformation of the substrate while ensuring sufficient adhesion between the photosensitive layer and the substrate. Is preferably 2.5 × 10 ² to 5 × 10 ⁴ N / m, more preferably 5 × 10 ² to 4 × 10 ⁴ N / m.

If the photosensitive element 1 is heated as described above, it is not necessary to pre-heat the base material. However, in order to further improve the adhesion between the photosensitive layer and the base material, the base material may be pre-heated. preferable. The preheating temperature at this time is preferably 30 to 180 ° C.

In this embodiment, instead of using a photosensitive element, the photosensitive resin composition of this embodiment is applied as a coating liquid to the surface of the substrate 100 where the touch panel electrodes 110 and 120 are provided and dried. The photosensitive layer 20 can be formed.

The photosensitive layer 20 preferably satisfies the above-described conditions of film thickness, visible light transmittance, and b ^* in the CIELAB color system.

In the second step of the present embodiment, the photosensitive layer 20 is exposed to the actinic ray L in a pattern via the photomask 130 (see FIG. 2B).

At the time of exposure, when the support film 10 on the photosensitive layer 20 is transparent, it can be exposed as it is, and when it is opaque, it is removed and then exposed. From the viewpoint of protecting the photosensitive layer, it is preferable to use a transparent polymer film as the support film, and expose the polymer film while leaving the polymer film remaining.

As the active light source used for exposure, a known active light source can be used, for example, a carbon arc lamp, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a xenon lamp, etc. Not limited.

At this time, the irradiation amount of actinic rays is usually 1 × 10 ² to 1 × 10 ⁴ J / m ² , and heating can be accompanied during irradiation. If the irradiation amount of actinic rays is less than 1 × 10 ² J / m ² , the photocuring effect tends to be insufficient, and if it exceeds 1 × 10 ⁴ J / m ² , the photosensitive layer tends to discolor. is there.

In the third step of the present embodiment, the exposed photosensitive layer is developed with a developer to remove the unexposed portions, and the photosensitive resin composition of the present embodiment having a thickness of 10 μm or less covering a part or all of the electrodes. A protective film 22 made of a cured product is formed. The formed protective film 22 can have a predetermined pattern.

In addition, after exposure, when the support film is laminated | stacked on the photosensitive layer, after removing it, development which removes the unexposed part by a developing solution is performed.

As a development method, development is performed by a known method such as spraying, showering, rocking dipping, brushing, scraping, etc., using a known developing solution such as an alkaline aqueous solution, an aqueous developer, or an organic solvent, and unnecessary portions are removed. Among them, it is preferable to use an alkaline aqueous solution from the viewpoint of environment and safety.

Examples of the base of the alkaline aqueous solution include alkali hydroxide (lithium, sodium or potassium hydroxide, etc.), alkali carbonate (lithium, sodium or potassium carbonate or bicarbonate, etc.), alkali metal phosphate (potassium phosphate, etc.) , Sodium phosphate, etc.), alkali metal pyrophosphates (sodium pyrophosphate, potassium pyrophosphate, etc.), tetramethylammonium hydroxide, triethanolamine, etc. Among them, tetramethylammonium hydroxide, etc. are preferred. It is done.

Further, an aqueous solution of sodium carbonate is also preferably used. For example, a dilute solution of sodium carbonate (0.5 to 5% by weight aqueous solution) at 20 to 50 ° C. is preferably used.

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

In addition, a surfactant, an antifoaming agent, a small amount of an organic solvent for promoting development, and the like can be mixed in the alkaline aqueous solution.

Further, the base of the alkaline aqueous solution remaining in the photosensitive layer after development and photocuring is converted into an acid by a known method such as spraying, rocking immersion, brushing or scraping using an organic acid, an inorganic acid or an aqueous acid solution thereof. It can be treated (neutralized).

Furthermore, after the acid treatment (neutralization treatment), a step of washing with water can be performed.

After development, the cured product may be further cured by exposure (for example, 5 × 10 ³ to 2 × 10 ⁴ J / m ² ) as necessary. Note that the photosensitive resin composition of the present embodiment exhibits excellent adhesion to a metal even without a heating step after development, but if necessary, instead of exposure after development or in combination with exposure. Heat treatment (80 to 250 ° C.) may be performed.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[Preparation of binder polymer solution (A1)]
A flask equipped with a stirrer, reflux condenser, inert gas inlet and thermometer was charged with (1) shown in Table 1, heated to 80 ° C. in a nitrogen gas atmosphere, and the reaction temperature was 80 ° C. ± 2 While maintaining the temperature, (2) shown in Table 1 was added dropwise uniformly over 4 hours. After the dropwise addition of (2), stirring was continued at 80 ° C. ± 2 ° C. for 6 hours, and a binder polymer solution having a weight average molecular weight of about 65,000, an acid value of 78 mgKOH / g, and a hydroxyl value of 2 mgKOH / g (solid content 45 % By mass) (A1) was obtained.

[Preparation of binder polymer solution (A2)]
In the same manner as in the above (A1), a binder polymer solution (solid content 45 mass%) (A2) having a weight average molecular weight of about 80,000, an acid value of 115 mgKOH / g, and a hydroxyl value of 1 mgKOH / g was obtained.

[Preparation of binder polymer solution (A3)]
In the same manner as (A1) above, a binder polymer solution (solid content 45% by weight) (A3) having a weight average molecular weight of about 45,000, an acid value of 78 mgKOH / g, and a hydroxyl value of 43 mgKOH / g was obtained.

[Preparation of binder polymer solution (A4)]
In the same manner as in the above (A1), a binder polymer solution (solid content 45% by weight) (A4) having a weight average molecular weight of about 47,000, an acid value of 78 mgKOH / g and a hydroxyl value of 129 mgKOH / g was obtained.

[Preparation of binder polymer solution (A5)]
MIS-115 (methacrylic acid / N-cyclohexylmaleimide / dicyclopentanyl methacrylate / 2-hydroxyethyl methacrylate copolymer / reaction product of 2-hydroxyethyl methacrylate and methacrylic acid (2-isocyanatoethyl) (mass ratio) A 12.2 / 10.9 / 26 / 18.6 / 32.3) propylene glycol monomethyl ether acetate / methyl lactate solution was used with a weight average molecular weight of about 26,000, an acid value of 55 mgKOH / g, and a hydroxyl value. Was 80.2 mgKOH / g.

 

The weight average molecular weight (Mw) was measured by gel permeation chromatography (GPC), and was derived by conversion using a standard polystyrene calibration curve. The GPC conditions are shown below.
GPC condition Pump: Hitachi L-6000 type (product name, manufactured by Hitachi, Ltd.)
Column: Gelpack GL-R420, Gelpack GL-R430, Gelpack GL-R440 (above, manufactured by Hitachi Chemical Co., Ltd., product name)
Eluent: Tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 2.05 mL / min Detector: Hitachi L-3300 type RI (manufactured by Hitachi, Ltd., product name)

[Measurement method of acid value]
The acid value was measured as follows. First, the binder polymer solution was heated at 130 ° C. for 1 hour to remove volatile components to obtain a solid content. Then, after precisely weighing 1 g of the polymer whose acid value is to be measured, 30 g of acetone was added to this polymer and dissolved uniformly. Next, an appropriate amount of an indicator, phenolphthalein, was added to the solution, and titration was performed using a 0.1N aqueous KOH solution. And the acid value was computed by following Formula.
Acid value = 10 × Vf × 56.1 / (Wp × I)
In the formula, Vf represents the titration amount (mL) of phenolphthalein, Wp represents the weight (g) of the measured resin solution, and I represents the ratio (mass%) of the non-volatile content in the measured resin solution.

[Measurement method of hydroxyl value]
The hydroxyl group was measured as follows. First, the binder polymer solution was heated at 130 ° C. for 1 hour to remove volatile components to obtain a solid content. Then, after precisely weighing 1 g of the polymer whose hydroxyl value is to be measured, the accurately weighed photosensitive resin composition is put in an Erlenmeyer flask, and 10 mL of 10% by mass acetic anhydride pyridine solution is added and uniformly dissolved. Heated at 0 ° 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. Then, using an automatic titrator (“COM-1700” manufactured by Hiranuma Sangyo Co., Ltd.), 0.5 mol / L potassium hydroxide ethanol It was measured by neutralization titration with a solution.

Example 1
[Preparation of Photosensitive Resin Composition Solution (V-1) for Forming Protective Film]
The materials shown in Table 2 were mixed for 15 minutes using a stirrer to prepare a photosensitive resin composition solution (V-1) for forming a protective film.

 

[Preparation of Photosensitive Element (E-1) for Forming Protective Film]
A polyethylene terephthalate film having a thickness of 50 μm was used as the support film, and the photosensitive resin composition solution (V-1) was evenly applied onto the support film using a comma coater, and 3 times with a 100 ° C. hot air convection dryer. The solvent was removed by drying for minutes to form a photosensitive layer (photosensitive resin composition layer) made of the photosensitive resin composition. The resulting photosensitive layer had a thickness of 5 μm.

Next, a polyethylene film having a thickness of 25 μm was further laminated as a cover film on the obtained photosensitive layer to produce a photosensitive element (E-1) for forming a protective film.

[Measurement of transmittance of photosensitive layer]
Laminator (manufactured by Hitachi Chemical Co., Ltd., trade name: HLM-3000) so that the photosensitive layer is in contact with a 1 mm thick glass substrate while peeling the polyethylene film of the obtained photosensitive element (E-1) , Using a substrate with a roll temperature of 120 ° C., a substrate feed rate of 1 m / min, and a pressure (cylinder pressure) of 4 × 10 ⁵ Pa (thickness of 1 mm, length of 10 cm × width of 10 cm, the linear pressure at this time is (9.8 × 10 ³ N / m) was laminated to prepare a laminate in which a photosensitive layer and a support film were laminated on a glass substrate.

Next, a parallel light exposure machine (EXM1201 manufactured by Oak Manufacturing Co., Ltd.) is used for the photosensitive layer of the obtained laminate, and the exposure amount is 5 × 10 ² J / m ² from the upper side of the photosensitive layer (i line). (Measurement value at a wavelength of 365 nm) After irradiation with ultraviolet rays, the support film was removed to obtain a transmittance measurement sample having a photosensitive layer (photocured cured film) thickness of 5.0 μm.

Subsequently, the visible light transmittance of the obtained sample was measured in a measurement wavelength range of 400 to 700 nm using an ultraviolet-visible spectrophotometer (U-3310) manufactured by Hitachi Instrument Service Co., Ltd. The transmittance of the obtained photosensitive layer at a wavelength of 400 nm is 97% at a wavelength of 700 nm, 96% at a wavelength of 550 nm, and 94% at a wavelength of 400 nm. The transmittance was secured.

[Measurement of b ^* of photosensitive layer]
Laminator (Hitachi, Hitachi) so that the photosensitive layer is in contact with a 0.7 mm thick glass substrate (b ^* : 0.1 to 0.2) while peeling the polyethylene film of the obtained photosensitive element (E-1). Using a Kasei Kogyo Co., Ltd. product name, HLM-3000, roll temperature 120 ° C., substrate feed rate 1 m / min, pressure bonding pressure (cylinder pressure) 4 × 10 ⁵ Pa (thickness 1 mm, length 10 cm × Since a substrate having a width of 10 cm was used, the substrate was laminated under the condition that the linear pressure at this time was 9.8 × 10 ³ N / m) to produce a substrate in which a photosensitive layer and a support film were laminated on a glass substrate. .

Next, the obtained photosensitive layer was subjected to an exposure amount of 5 × 10 ² J / m ² (i-line (wavelength 365 nm) from the upper side of the photosensitive layer side using a parallel light exposure machine (EXM1201 manufactured by Oak Manufacturing Co., Ltd.). )), After irradiating with ultraviolet rays, the support film is removed and further irradiated with ultraviolet rays (measured value at i-line (wavelength 365 nm)) with an exposure amount of 1 × 10 ⁴ J / m ² from above the photosensitive layer side. Then, a sample for b ^* measurement having a photosensitive layer (photocured cured film) thickness of 5.0 μm was obtained.

Next, the obtained sample was measured for b ^* in the CIELAB color system at a light source setting of D65 and a viewing angle of 2 ° using a spectrocolorimeter (CM-5) manufactured by Konica Minolta.

The b ^* of the photosensitive layer was 0.63, confirming that it had a good b ^* .

[Salt spray test of photosensitive layer (artificial sweat resistance evaluation test)]
Laminator (manufactured by Hitachi Chemical Co., Ltd.) so that the photosensitive layer is in contact with the polyimide film with sputtered copper (manufactured by Toray Film Processing Co., Ltd.) while peeling off the polyethylene film of the obtained photosensitive element (E-1). Using a substrate having a roll temperature of 120 ° C., a substrate feed speed of 1 m / min, and a pressure bonding pressure (cylinder pressure) of 4 × 10 ⁵ Pa (thickness of 1 mm, length of 10 cm × width of 10 cm). Therefore, the laminate was laminated under the condition that the linear pressure at this time was 9.8 × 10 ³ N / m), and a laminate in which the photosensitive layer and the support film were laminated on the sputtered copper was produced.

Next, a parallel light exposure machine (EXM1201 manufactured by Oak Manufacturing Co., Ltd.) was used for the photosensitive layer of the obtained laminate, and the exposure amount was 5 × 10 ² J / m ² (i-line ( Measured value at a wavelength of 365 nm), after irradiating with ultraviolet rays, the support film is removed, and further the ultraviolet ray is irradiated at an exposure amount of 1 × 10 ⁴ J / m ² from above the photosensitive layer side (measured value at i-line (wavelength 365 nm)). Irradiation was performed to obtain a sample for evaluating artificial sweat resistance in which a 5.0 μm-thick protective layer formed by curing the photosensitive layer was formed.

Next, referring to the JIS standard (Z 2371), using the salt spray tester (STP-90V2 manufactured by Suga Test Instruments Co., Ltd.), the above-mentioned sample was placed in the test tank, and the salt water having a concentration of 50 g / L. (PH = 6.7) was sprayed for 48 hours at a test bath temperature of 35 ° C. and a spray amount of 1.5 mL / h. After spraying, the salt water was wiped off, the surface state of the sample for evaluation was observed, and evaluation was performed according to the following scores.
A: No change on the surface of the protective layer B: A slight trace can be seen on the surface of the protective layer, but copper does not change.
C: Traces are visible on the surface of the protective layer, but copper is unchanged.
D: There is a trace on the surface of the protective layer, and copper discolors.
When the surface state of the sample for evaluation was observed, a very slight trace was seen on the surface of the protective layer, but the copper was unchanged and the evaluation was B.

[Development residue test of photosensitive layer]
Laminator (manufactured by Hitachi Chemical Co., Ltd.) so that the photosensitive layer is in contact with the polyimide film with sputtered copper (manufactured by Toray Film Processing Co., Ltd.) while peeling off the polyethylene film of the obtained photosensitive element (E-1). Using a substrate having a roll temperature of 120 ° C., a substrate feed speed of 1 m / min, and a pressure bonding pressure (cylinder pressure) of 4 × 10 ⁵ Pa (thickness of 1 mm, length of 10 cm × width of 10 cm). Therefore, the laminate was laminated under the condition that the linear pressure at this time was 9.8 × 10 ³ N / m), and a laminate in which the photosensitive layer and the support film were laminated on the sputtered copper was produced.

After the laminate obtained above was prepared, it was stored for 24 hours at 23 ° C. and 60%, and then the actinic ray transmitting portion and the actinic ray shielding portion were alternately patterned, and a photo with a line / space of 300 μm / 300 μm. Using a mask, a photomask is placed on a support film, and using a parallel light exposure machine (EXM1201 manufactured by Oak Manufacturing Co., Ltd.), the exposure amount is 5 × 10 ² J / m ² from above the photomask surface. (Measured value at i-line (wavelength 365 nm)), ultraviolet rays were imagewise irradiated.

Next, the support film laminated on the photosensitive layer is removed, and spray development is performed at 30 ° C. for 40 seconds using a 1.0% by mass aqueous sodium carbonate solution to selectively remove the photosensitive layer, and a protective film pattern Formed. The substrate surface state of the portion of the obtained substrate with the protective film pattern where the photosensitive layer was selectively removed was observed with a microscope, and the development residue was evaluated according to the following ratings.
A: No change on the substrate surface B: Copper on the substrate surface is slightly discolored, but there is no development residue.
C: Copper on the surface of the substrate is slightly discolored, and a development residue is slightly generated.
D: Development residue is generated.
When the surface state of the sample for evaluation was observed, there was no change on the surface of the substrate, and the evaluation was A.

[Cross-cut adhesion test of photosensitive layer]
Laminator (manufactured by Hitachi Chemical Co., Ltd.) so that the photosensitive layer is in contact with the polyimide film with sputtered copper (manufactured by Toray Film Processing Co., Ltd.) while peeling off the polyethylene film of the obtained photosensitive element (E-1). Using a substrate having a roll temperature of 120 ° C., a substrate feed speed of 1 m / min, and a pressure bonding pressure (cylinder pressure) of 4 × 10 ⁵ Pa (thickness of 1 mm, length of 10 cm × width of 10 cm). Therefore, the laminate was laminated under the condition that the linear pressure at this time was 9.8 × 10 ³ N / m), and a laminate in which the photosensitive layer and the support film were laminated on the sputtered copper was produced.

Next, a parallel light exposure machine (EXM1201 manufactured by Oak Manufacturing Co., Ltd.) is used for the photosensitive layer of the obtained laminate, and the exposure amount is 5 × 10 ² J / m ² from the upper side of the photosensitive layer (i line). (Measured value at wavelength 365 nm), after irradiating with ultraviolet rays, the support film is removed, and further at an exposure amount of 1 × 10 ⁴ J / m ² from above the photosensitive layer side (measured value at i-line (wavelength 365 nm)) To obtain a cross-cut adhesion test sample in which a 5.0 μm-thick protective layer formed by curing the photosensitive layer was formed.

Next, a cross cut test of 100 squares was performed with reference to JIS standard (K5400). Using a cutter knife on the test surface, make a 1 x 1 mm square cut on the grid, and firmly press Mending Tape # 810 (manufactured by 3M Co., Ltd.) on the grid, so that the end of the tape is approximately 0 °. After slowly peeling off at an angle, the cross-cut state was observed, and cross-cut adhesion was evaluated according to the following score.
A: Almost 100% of the entire area is in close contact.
B: 95% or more of the entire area remains adhered.
B to C: 85 to 95% of the total area remains adhered.
C: 65 to 85% of the total area remains adhered.
C to D: 35 to 65% of the total area remains adhered.
D: 0 to 35% of the total area remains adhered.
When the cross section of the evaluation sample was observed, 95% or more of the total area remained adhered to the sputtered copper, and the evaluation was B.

(Examples 2 to 8)
A photosensitive element was prepared in the same manner as in Example 1 except that the photosensitive resin composition solution shown in Tables 3 and 4 (the unit of numerical values in the table is part by mass) was used, and measurement of transmittance, salt spray test A development residue test and a cross-cut adhesion test were conducted. As shown in Tables 7 and 8, in Examples 1 to 8, all of the measurements of transmittance, salt spray resistance evaluation, and cross-cut adhesion were good results. In addition, b ^* of the photosensitive resin composition layers of Examples 2 to 8 was 0.62 to 0.63, and good b ^* was secured.

 

 

 

 

(A1): Methacrylic acid / Methyl methacrylate / Ethyl acrylate = 12/58/30 (mass ratio), Acid value 78 (mgKOH / g), Hydroxyl value 2 (mgKOH / g)
(A2): Methacrylic acid / Methyl methacrylate / Ethyl acrylate = 17.5 / 52.5 / 30 (mass ratio), Acid value 115 (mgKOH / g), Hydroxyl value 1 (mgKOH / g)
(A3): methacrylic acid / methyl methacrylate / ethyl acrylate / 2-hydroxyethyl methacrylate = 12/48/30/10 (mass ratio), acid value 78 (mgKOH / g), hydroxyl value 43 (mgKOH / g )
(A4): methacrylic acid / methyl methacrylate / ethyl acrylate / 2-hydroxyethyl methacrylate = 12/28/30/30 (mass ratio), acid value 78 (mgKOH / g), hydroxyl value 129 (mgKOH / g )
(A5): methacrylic acid / N-cyclohexylmaleimide / dicyclopentanyl methacrylate / 2-hydroxyethyl methacrylate copolymer / reaction product of 2-hydroxyethyl methacrylate and methacrylic acid (2-isocyanatoethyl) (mass ratio) 12.2 / 10.9 / 26 / 18.6 / 32.3) propylene glycol monomethyl ether acetate / methyl lactate solution, acid value 55 (mgKOH / g), hydroxyl value 80.2 (mgKOH / g)
DPHA: dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd.), hydroxyl value 40 (mgKOH / g)
TMPTA: trimethylolpropane triacrylate (manufactured by Nippon Kayaku Co., Ltd.), hydroxyl value 0 (mgKOH / g)
PET-30: Pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd.), hydroxyl value 110 (mgKOH / g)
A-9550: Dipentaerythritol polyacrylate (manufactured by Nippon Kayaku Co., Ltd.), hydroxyl value 40 (mgKOH / g)
A-9570: Dipentaerythritol polyacrylate (manufactured by Nippon Kayaku Co., Ltd.), hydroxyl value 70 (mgKOH / g)
A-TMM-3: Pentaerythritol triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.), hydroxyl value 110 (mgKOH / g)
A-TMMLMN: Pentaerythritol triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.), hydroxyl value 114 (mgKOH / g)
Irg-OXE01: 1,2-octanedione, 1-[(4-phenylthio)-, 2- (o-benzoyloxime)] (manufactured by BASF Corporation)
AMT: 3-amino-5-mercaptotriazole (manufactured by Wako Pure Chemical Industries, Ltd.)
HAT: 5-amino-1H-tetrazole (Toyobo Co., Ltd.)
PM21: Phosphate ester containing a photopolymerizable unsaturated bond (manufactured by Nippon Kayaku Co., Ltd.)
Antage W-500: 2,2'-methylene-bis (4-ethyl-6-tert-butylphenol) (manufactured by Kawaguchi Chemical Co., Ltd.)
Methyl ethyl ketone: manufactured by Tonen Chemical Co., Ltd.

 

 

(Comparative Examples 1 to 8)
A photosensitive element was prepared in the same manner as in Example 1 except that the photosensitive resin composition solution shown in Tables 5 and 6 (the unit of numerical values in the table is part by mass) was used, and measurement of transmittance, salt spray test A development residue test and a cross-cut adhesion test were conducted.

As shown in Table 8, in Comparative Examples 1 to 8 in which the hydroxyl value of the entire solid content of the photosensitive resin composition exceeded 40 mgKOH / g, the salt spray test was inferior.

DESCRIPTION OF SYMBOLS 1 ... Photosensitive element, 10 ... Support film, 20 ... Photosensitive layer 20, 30 ... Protective film, 100 ... Base material, 110, 120 ... Electrode for touch panels, 130 ... Photomask, 22 ... Protective film, 200 ... Touch panel sensor.

Claims (22)

1. A first step of providing a photosensitive layer comprising a photosensitive resin composition containing a binder polymer, a photopolymerizable compound, and a photopolymerization initiator on a substrate having a touch panel electrode;
   A second step of curing a predetermined portion of the photosensitive layer by irradiation with actinic rays;
   A third step of removing the photosensitive layer other than the predetermined portion and forming a protective film made of a cured product of the photosensitive resin composition having a thickness of 10 μm or less covering a part or all of the electrode;
   With
   The formation method of the protective film of the electrode for touchscreens whose hydroxyl value of the whole solid content of the said photosensitive resin composition is 40 mgKOH / g or less.
2. The method for forming a protective film for a touch panel electrode according to claim 1, wherein the binder polymer component has a hydroxyl value of 50 mgKOH / g or less.
3. The method for forming a protective film for a touch panel electrode according to claim 1 or 2, wherein the photopolymerizable compound component has a hydroxyl value of 90 mgKOH / g or less.
4. The method for forming a protective film for a touch panel electrode according to any one of claims 1 to 3, wherein the photosensitive resin composition further contains a phosphate ester containing a photopolymerizable unsaturated bond.
5. The method for forming a protective film for a touch panel electrode according to any one of claims 1 to 4, wherein the acid value of the binder polymer component is 120 mgKOH / g or less.
6. The method for forming a protective film for a touch panel electrode according to any one of claims 1 to 5, wherein the photosensitive layer has a visible light transmittance of 90% or more.
7. 7. The method for forming a protective film for a touch panel electrode according to claim 1, wherein the photosensitive layer has a b ^* in the CIELAB color system of −0.2 to 1.0.
8. The photosensitive resin composition according to any one of claims 1 to 7, further comprising one or more compounds selected from the group consisting of triazole compounds having amino groups and tetrazole compounds having amino groups. A method for forming a protective film for an electrode for a touch panel.
9. The method for forming a protective film for an electrode for a touch panel according to any one of claims 1 to 8, wherein the photopolymerization initiator contains an oxime ester compound or a phosphine oxide compound.
10. A photosensitive element comprising a support film and a photosensitive layer made of the photosensitive resin composition provided on the support film is prepared, and the photosensitive layer of the photosensitive element is transferred onto the base material to transfer the photosensitive element. The method for forming a protective film for a touch panel electrode according to any one of claims 1 to 9, wherein a photosensitive layer is provided.
11. A photosensitive resin composition containing a binder polymer, a photopolymerizable compound, and a photopolymerization initiator,
    The photosensitive resin composition used for protective film formation of the electrode for touchscreens whose hydroxyl value in the whole solid of the said photosensitive resin composition is 40 mgKOH / g or less.
12. The photosensitive resin composition according to claim 11, wherein the binder polymer component has a hydroxyl value of 50 mgKOH / g or less.
13. The photosensitive resin composition according to claim 11 or 12, wherein the photopolymerizable compound component has a hydroxyl value of 90 mgKOH / g or less.
14. The photosensitive resin composition according to any one of claims 11 to 13, wherein the acid value of the binder polymer component is 120 mgKOH / g or less.
15. The photosensitive resin composition according to any one of claims 11 to 14, further comprising a phosphate ester containing a photopolymerizable unsaturated bond.
16. The photosensitive resin composition according to any one of claims 11 to 15, which has a visible light transmittance of 90% or more when a film having a thickness of 5 µm is formed.
17. The photosensitive resin composition according to any one of claims 11 to 16, wherein b ^* in the CIELAB color system when a film having a thickness of 5 µm is formed is -0.2 to 1.0.
18. The photosensitive resin composition according to any one of claims 11 to 17, further comprising one or more compounds selected from the group consisting of a triazole compound having an amino group and a tetrazole compound having an amino group.
19. The photosensitive resin composition according to any one of claims 11 to 18, wherein the photopolymerization initiator contains an oxime ester compound or a phosphine oxide compound.
20. A photosensitive element comprising: a support film; and a photosensitive layer comprising the photosensitive resin composition according to any one of claims 11 to 19 provided on the support film.
21. The photosensitive element according to claim 20, wherein the photosensitive layer has a thickness of 10 μm or less.
22. A method of manufacturing a touch panel sensor, comprising: forming a protective film covering a part or all of the electrode by a method according to any one of claims 1 to 10 on a substrate having a touch panel electrode. .
    

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