Transparent resin composition, dry film, cured product, and electronic component

Abstract

The present invention provides a technology related to a transparent resin composition having excellent transparency, developability, and adhesiveness.　One embodiment of the present invention pertains to a transparent resin composition. The transparent resin composition has an alkali-soluble polymer (A), a carboxyl group-containing urethane resin (B), and a polymerizable compound (C). The alkali-soluble polymer (A) includes a cyclohexyl group and a carboxyl group. The carboxyl group-containing urethane resin (B) is obtained by using a compound having an isocyanate group that is not directly bonded to an aromatic ring. The polymerizable compound (C) has an ethylene oxide skeleton. When the total of the alkali-soluble polymer (A) and the carboxyl group-containing urethane resin (B) is defined as 100 parts by mass, the content of the alkali-soluble polymer (A) is 45-75 parts by mass in terms of solid content.

Description

Transparent resin composition, dry film, cured product, and electronic component

[0001] The present invention relates to a transparent resin composition, a dry film, a cured product, and an electronic component.

[0002] Transparent insulating protective films are required as protective films for transparent electronic components such as transparent antennas and transparent displays. Conventionally, thermosetting resin compositions have been known as materials for forming this type of insulating protective film (see Patent Document 1). Furthermore, transparent electronic components are becoming thinner, lighter, and more flexible, and the use of resin films as transparent organic substrates has been considered. Examples of resin films include polyimide, polyethylene terephthalate, and cycloolefin polymer (COP). Of these, COP, which has excellent optical properties and dimensional stability, is preferably used.

[0003] JP 2022-18893 A

[0004] The properties required for protective films for transparent electronic components include transparency, developability, and adhesion to the substrate (hereinafter simply referred to as adhesion). In recent years, as transparent electronic components have become smaller and thinner, protective films for transparent electronic components are required to have finer and more precise opening diameters. However, protective films obtained using conventional thermosetting resin compositions have limited developability, making it difficult to further refine and improve the precision of opening diameters. In particular, when microfabrication is performed using a patterning process, physical treatments such as surface roughening of the organic substrate to ensure the transparency of the organic substrate cannot be performed to achieve the anchoring effect. On the other hand, if the affinity between the organic substrate and the protective film is too high, it becomes difficult to wash away the unexposed areas by development. Therefore, it is necessary to select a protective film with appropriate adhesion to the organic substrate.

[0005] The present invention has been made in view of the above-mentioned problems, and aims to provide a transparent resin composition that is excellent in transparency, developability, and adhesion to organic substrates (particularly adhesion to COP substrates). The present invention also provides a dry film having a resin layer obtained using the resin composition, a cured product of the transparent resin composition or the resin layer, and an electronic component having the cured product.

[0006] One aspect of the present invention is a transparent resin composition. The transparent resin composition includes an alkali-soluble polymer (A) containing a cyclohexyl group and a carboxyl group, a carboxyl group-containing urethane resin (B) obtained using a compound having an isocyanate group not directly bonded to an aromatic ring, and a polymerizable compound (C) having an ethylene oxide skeleton. The content of the alkali-soluble polymer (A) is 45 to 75 parts by mass, calculated as solid content, relative to 100 parts by mass of the total of the alkali-soluble polymer (A) and the carboxyl group-containing urethane resin (B). In the transparent resin composition of the above aspect, the alkali-soluble polymer (A) may have an ethylenically unsaturated group, and the polymerizable compound (C) may have an unsaturated double bond. In the transparent resin composition of the above aspect, the content of the polymerizable compound (C) may be 20 parts by mass or more, calculated as solid content, relative to 100 parts by mass of the total of the alkali-soluble polymer (A) and the carboxyl group-containing urethane resin (B). The transparent resin composition of any of the above embodiments may contain a polymerization initiator. The transparent resin composition of any of the above embodiments may contain an epoxy resin.

[0007] Another aspect of the present invention is a dry film, which is obtained by applying the transparent resin composition of any of the above-described aspects to a first film.

[0008] Yet another aspect of the present invention is a cured product. The cured product can be obtained using the transparent resin composition of any of the above-described aspects or the dry film of the above-described aspect. The cured product of the above aspect may have a transmittance of 85% or more as measured under the following conditions. (Conditions) The transparent resin composition is applied to a first film so that the film thickness after drying is 8 μm, and the film is heated and dried in a hot air dryer at 80°C for 30 minutes to form a resin layer. A COP having a film thickness of 50 μm is attached to the exposed surface of the resin layer, and lamination is performed. After solid exposure using a parallel light exposure machine, the first film is peeled off, and the film is exposed to 1% NaCl at 30°C. ２ CO ３ The coating is developed for 30 seconds using an aqueous solution at a spray pressure of 0.1 MPa. The coating is then thermally cured by heating in a hot air circulation drying oven at 130°C for 60 minutes, yielding a substrate for transmittance measurement on which a cured product with a film thickness of 8 μm has been formed. The transmittance of the resulting cured product in the range of 380 to 780 nm is measured using an ultraviolet-visible spectrophotometer. The cured product of any of the above embodiments may be used as an insulating protective film for transparent electronic components.

[0009] According to the present invention, a technique can be provided for a transparent resin composition that is excellent in transparency, developability, and adhesion.

[0010] Hereinafter, embodiments of the present invention will be described in detail. In this specification, the notation "a to b" in the description of a numerical range means that the range is from a to b, unless otherwise specified. In addition, in this specification, when "(meth)acrylic" is used, it is intended to include both "methacrylic" and "acrylic."

[0011] The transparent resin composition according to the embodiment includes an alkali-soluble polymer (A), a carboxyl group-containing urethane resin (B), and a polymerizable compound (C). The transparent resin composition according to the embodiment satisfies a transmittance of 85% or more and a haze of less than 4.0, measured under atmospheric conditions. The transmittance and haze of the transparent resin composition are measured as follows. First, the transparent resin composition is applied to a 75 mm x 14 mm, 40 μm thick Teflon® sheet so that the dried film thickness is 8 μm. The composition is then dried in a hot air dryer at 80°C for 30 minutes to form a resin layer. The composition is then cut into 2 cm x 4 cm and 3 cm x 3 cm pieces, and the Teflon® is peeled off to obtain test pieces. The transmittance is measured by a transmission method using a 2 cm x 4 cm test piece at wavelengths of 380 to 780 nm using a UV-visible spectrophotometer (V-570, manufactured by JASCO Corporation). The haze is measured using a 3 cm x 3 cm test piece with a haze meter (NDH7000II, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0012] (Alkali-soluble polymer (A)) The alkali-soluble polymer (A) contains a cyclohexyl group and a carboxyl group. When the alkali-soluble polymer (A) contains a carboxyl group, it is possible to improve adhesion to the substrate and developability. The alkali-soluble polymer (A) may be a carboxyl group-containing resin having an ethylenically unsaturated group, or a carboxyl group-containing resin not having an ethylenically unsaturated group.

[0013] Examples of the alkali-soluble polymer (A) include a copolymer of a cyclohexyl group-containing monomer and a carboxyl group-containing monomer, a modified product in which the terminal portion of a cyclohexyl group-containing polymer is substituted with a carboxyl group-containing functional group, a modified product in which the terminal portion of a carboxyl group-containing polymer is substituted with a cyclohexyl group-containing functional group, etc. The alkali-soluble polymer (A) is preferably a copolymer of a cyclohexyl group-containing monomer and a carboxyl group-containing monomer.

[0014] The monomer having a cyclohexyl group is not particularly limited, and examples thereof include compounds containing a cyclohexyl group and a (meth)acroyl group, such as cyclohexyl (meth)acrylate and 3,4-epoxycyclohexyl (meth)acrylate.

[0015] The monomer containing a carboxyl group is not particularly limited, and examples thereof include compounds containing a carboxyl group and a (meth)acroyl group, such as (meth)acrylic acid and carboxyethyl (meth)acrylate.

[0016] The alkali-soluble polymer (A) can be produced by copolymerizing these monomers under conventionally known conditions. The ratio of the cyclohexyl group-containing monomer to the carboxyl group-containing monomer can be any ratio, but a ratio of 30:70 to 70:30 by mass is preferred in terms of adhesion.

[0017] In this case, the monomer of the alkali-soluble polymer (A) may contain a monomer other than the monomer having a cyclohexyl group and the monomer containing a carboxyl group. In other words, the alkali-soluble polymer (A) may be a copolymer of a monomer having a cyclohexyl group, a monomer containing a carboxyl group, and a monomer other than these.

[0018] The alkali-soluble polymer (A) preferably has an ethylenically unsaturated group (a hydrocarbon group having an unsaturated double bond), and the ethylenically unsaturated group is preferably a (meth)acryloyl group.

[0019] The alkali-soluble polymer (A) having an ethylenically unsaturated group can be produced, for example, by adding a compound having one epoxy group and one or more ethylenically unsaturated groups (preferably (meth)acryloyl groups) in the molecule, such as glycidyl (meth)acrylate or α-methylglycidyl (meth)acrylate, to the copolymer of a monomer having a cyclohexyl group and a monomer containing a carboxyl group as described above.

[0020] The alkali-soluble polymer (A) may be used alone or in combination of two or more.

[0021] The acid value of the alkali-soluble polymer (A) is preferably 20 to 300 (mgKOH / g), more preferably 40 to 250 (mgKOH / g), and particularly preferably 50 to 200 (mgKOH / g). When the acid value of the alkali-soluble polymer (A) is within this range, it becomes easy to develop the coating film or resin layer after exposure with an aqueous alkaline solution, and it becomes easier to draw a more normal cured product pattern.

[0022] The carboxylic acid equivalent of the alkali-soluble polymer (A) is preferably 100 to 1,000 (g / eq), more preferably 200 to 800 (g / eq), and particularly preferably 300 to 600 (g / eq). By setting the carboxylic acid equivalent of the alkali-soluble polymer (A) within this range, it becomes easier to obtain a cured product having excellent adhesion and environmental resistance.

[0023] The cyclohexyl group equivalent of the alkali-soluble polymer (A) is preferably 100 to 1,000 (g / eq), more preferably 200 to 800 (g / eq), and particularly preferably 300 to 600 (g / eq). By setting the cyclohexyl group equivalent of the alkali-soluble polymer (A) within this range, it becomes easier to obtain a cured product with excellent adhesion and environmental resistance.

[0024] When the alkali-soluble polymer (A) contains a (meth)acryloyl group, the (meth)acrylic equivalent of the alkali-soluble polymer (A) is preferably 100 to 2000 (g / eq), more preferably 200 to 1800 (g / eq), and particularly preferably 300 to 1500 (g / eq). By setting the carboxylic acid equivalent of the alkali-soluble polymer (A) within this range, it becomes easier to obtain a cured product that has excellent resolution, adhesion, and environmental resistance.

[0025] The weight-average molecular weight of the alkali-soluble polymer (A) varies depending on the resin skeleton, but can be 1,500 to 150,000, preferably 1,500 to 100,000, more preferably 1,500 to 50,000, and particularly preferably 1,500 to 40,000. When the weight-average molecular weight of the alkali-soluble polymer (A) is within this range, a transparent resin composition and a dry film can be obtained that are excellent in tack-free performance, storage stability, moisture resistance of the coating film or resin layer after exposure, and developability, and that can suppress film loss during development and a decrease in resolution.

[0026] The alkali-soluble polymer (A) may be used alone or in combination of two or more.

[0027] (Carboxyl Group-Containing Urethane Resin (B)) The carboxyl group-containing urethane resin (B) is obtained using a compound having an isocyanate group that is not directly bonded to an aromatic ring. The transparent resin composition of this embodiment contains the carboxyl group-containing urethane resin (B), which improves adhesion to the base and developability. The carboxyl group-containing urethane resin (B) may be a carboxyl group-containing urethane resin having an ethylenically unsaturated group, or a carboxyl group-containing urethane resin not having an ethylenically unsaturated group. Among these, a carboxyl group-containing urethane resin having an ethylenically unsaturated group is preferred because it has excellent photocurability and development resistance. The carboxyl group-containing urethane resin (B) preferably has a cyclohexyl group. This can further improve adhesion to the base.

[0028] Specifically, the carboxyl group-containing urethane resin (B) is preferably a urethane resin having a phenolic hydroxyl group introduced at its terminal by the reaction of a compound (a) having an isocyanate group not directly bonded to an aromatic ring, a compound (b) having two or more alcoholic hydroxyl groups in one molecule, and a compound (c) having one alcoholic hydroxyl group and one or more phenolic hydroxyl groups in one molecule, which also functions as a reaction terminator. However, other examples include a urethane resin obtained by the reaction of a compound (a) having an isocyanate group not directly bonded to an aromatic ring with a compound (b) having two or more alcoholic hydroxyl groups in one molecule, in which a phenolic hydroxyl group is introduced into the molecular side chain using a compound having a phenolic hydroxyl group and two or more alcoholic hydroxyl groups as compound (b), or a urethane resin in which a carboxyl group is introduced into the molecular side chain using a compound having a carboxyl group and two or more alcoholic hydroxyl groups in one molecule. In the latter urethane resin, the above-mentioned compound (c) having one alcoholic hydroxyl group and one or more phenolic hydroxyl groups in one molecule can be used as an end-capping agent (reaction terminator). In addition, various conventionally known reaction terminators can be used, such as monohydroxyl compounds such as aliphatic alcohols and monohydroxymono(meth)acrylate compounds, and monocarboxylic acids having functional groups capable of undergoing an addition reaction or condensation reaction with an isocyanate group, such as an alcoholic hydroxyl group, an amino group, or a thiol group.

[0029] For example, in the case of the above-mentioned suitable urethane resin, the carboxyl group-containing urethane resin (B) may be prepared by mixing together and reacting a compound (a) having an isocyanate group not directly bonded to an aromatic ring, a compound (b) having two or more alcoholic hydroxyl groups per molecule, and a compound (c) having one alcoholic hydroxyl group per molecule, or by reacting the compound (a) having an isocyanate group not directly bonded to an aromatic ring with the compound (b) having two or more alcoholic hydroxyl groups per molecule, followed by reaction with the compound (c) having one alcoholic hydroxyl group per molecule, which also functions as a reaction terminator. In the case of the other urethane resins described above, the compound (a) having an isocyanate group not directly bonded to an aromatic ring, the compound (b) having a phenolic hydroxyl group and / or a carboxyl group and two or more alcoholic hydroxyl groups in one molecule, and the reaction terminator may be mixed together and reacted at once, but from the viewpoint of molecular weight adjustment, the compound (a) having an isocyanate group not directly bonded to an aromatic ring may be reacted with the compound (b), and then the reaction terminator may be reacted.

[0030] The reaction proceeds without a catalyst by stirring and mixing at room temperature to 100° C., but to increase the reaction rate, it is preferable to heat to 70 to 100° C. The appropriate reaction ratios (molar ratios) of the components (a) to (c) are (a):(b)=1:1 to 2:1, preferably 1:1 to 1.5:1, and (a+b):(c)=1:0.01 to 0.5, preferably 1:0.02 to 0.3.

[0031] The compound (a) having an isocyanate group not directly bonded to an aromatic ring can be any of various conventionally known compounds having an isocyanate group not directly bonded to an aromatic ring, and is not limited to any specific compound. Specific examples of the compound (a) having an isocyanate group not directly bonded to an aromatic ring include aliphatic diisocyanates such as hexamethylene diisocyanate, branched aliphatic diisocyanates such as trimethylhexamethylene diisocyanate, and alicyclic diisocyanates such as isophorone diisocyanate, (o-, m-, or p-)-(hydrogenated)xylene diisocyanate, methylenebis(cyclohexyl isocyanate), cyclohexane-1,3-dimethylene diisocyanate, and cyclohexane-1,4-dimethylene diisocyanate. Among these, hexamethylene diisocyanate, which is an aliphatic diisocyanate, and trimethylhexamethylene diisocyanate, which is a branched aliphatic diisocyanate, are preferred. These compounds having an isocyanate group not directly bonded to an aromatic ring can be used alone or in combination of two or more. When these diisocyanate compounds are used, a cured product having excellent low coloration, environmental resistance, and low warpage can be obtained. Furthermore, aromatic diisocyanates can also be used within a range that does not impair the effects of the present invention.

[0032] Next, as the compound (b) having two or more alcoholic hydroxyl groups, various conventionally known polyols can be used, and are not limited to specific compounds, but suitable compounds include polycarbonate polyols such as polycarbonate diols, polyether polyols, polyester polyols, polyolefin polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, hydrogenated polybutadiene polyols, hydrogenated isoprene polyols, phosphorus-containing diols, bisphenol A alkylene oxide adduct diols, compounds having a carboxyl group and an alcoholic hydroxyl group, compounds having a phenolic hydroxyl group and an alcoholic hydroxyl group, phosphorus-containing polyols, etc. Among these, polycarbonate polyols are preferred because they can give cured products with excellent weather resistance and flexibility. Examples of polycarbonate diols include polycarbonate diols (b-1) containing repeating units derived from one or more linear aliphatic diols as structural units, polycarbonate diols (b-2) containing repeating units derived from one or more alicyclic diols as structural units, and polycarbonate diols (b-3) containing repeating units derived from both linear aliphatic diols and alicyclic diols as structural units. Furthermore, when compounds (b-4) containing a carboxyl group and two or more alcoholic hydroxyl groups, or compounds (b-5) containing a phenolic hydroxyl group and two or more alcoholic hydroxyl groups, are used, functional groups (phenolic hydroxyl groups or carboxyl groups) can be provided on the molecular side chains. When phosphorus-containing polyols (b-6) are used, flame retardancy can be imparted to urethane resins. These compounds (b-1) to (b-6) can be used alone or in combination.

[0033] Specific examples of the polycarbonate diol (b-1) containing, as a constituent unit, a repeating unit derived from one or more of the above-mentioned linear aliphatic diols include polycarbonate diols derived from 1,6-hexanediol, polycarbonate diols derived from 1,5-pentanediol and 1,6-hexanediol, polycarbonate diols derived from 1,4-butanediol and 1,6-hexanediol, polycarbonate diols derived from 3-methyl-1,5-pentanediol and 1,6-hexanediol, and polycarbonate diols derived from 1,9-nonanediol and 2-methyl-1,8-octanediol.

[0034] Specific examples of the polycarbonate diol (b-2) containing repeating units derived from one or more of the above-mentioned alicyclic diols as constituent units include polycarbonate diols derived from 1,4-cyclohexanedimethanol.

[0035] A specific example of the polycarbonate diol (b-3) containing repeating units derived from both the linear aliphatic diol and the alicyclic diol as constituent units is a polycarbonate diol derived from 1,6-hexanediol and 1,4-cyclohexanedimethanol.

[0036] Specific examples of the compound (b-4) having a carboxyl group and two or more alcoholic hydroxyl groups include dimethylolpropionic acid, dimethylolbutanoic acid, etc. By using these compounds having a carboxyl group and two or more alcoholic hydroxyl groups, it is possible to easily introduce carboxyl groups into the urethane resin.

[0037] Specific examples of the compound (b-5) having a phenolic hydroxyl group and two or more alcoholic hydroxyl groups include 6-hydroxy-5-methyl-1,3-benzenedimethanol, 2,4-di(hydroxymethyl)-6-cyclohexylphenol, 3,3'-methylenebis(2-hydroxy-5-methyl-benzenemethanol), 4,4'-(1-methylethylidene)bis[2-methyl-6-hydroxymethylphenol], 4,4'-[1,4-phenylenebis(1-methylethylidene)bis[2-methyl-6-hydroxymethylphenol], Methylphenol], 2-hydroxy-5-fluoro-1,3-benzenedimethanol, 4,4'-methylenebis(2-methyl-6-hydroxymethylphenol), 4,4'-methylenebis(2,5-dimethyl-3-hydroxymethylphenol), 4,4'-cyclohexylidenebis(2-methyl-6-hydroxymethylphenol), 4,4'-cyclohexylidenebis(2-cyclohexyl-6-hydroxymethylphenol), 2,6-bis[(2-hydroxy-3-hydroxymethyl-5-methylphenyl)methyl]-4-methyl phenol, 2-hydroxy-5-ethyl-1,3-benzenedimethanol, 2-hydroxy-4,5-dimethyl-1,3-benzenedimethanol, 2-hydroxy-5-(1-methylpropyl)-1,3-benzenedimethanol, 4-(1,1-dimethylethyl)-2-hydroxy-1,3-benzenedimethanol, 2-hydroxy-5-cyclohexyl-1,3-benzenedimethanol, 2-hydroxy-5-(1,1,3,3-tetramethylbutyl)-1,3-benzenedimethanol, 2,6-bis[(4-hydroxy-3-hydroxypropyl)-1,3-benzenedimethanol], 2,6-bis[(4-hydroxy-3-hydroxymethyl-2,5-dimethylphenyl)methyl]-4-cyclohexylphenol, 2-hydroxy-1,3,5-benzenetrimethanol, 3,5-dimethyl-2,4,6-trihydroxymethylphenol, 4,4',4"-ethylidinetris(2-methyl-6-hydroxymethylphenol), 2,3,5,6-tetra(hydroxymethyl)-1,4-benzenediol, 4,4'-methylenebis[2,6-bis(hydroxymethyl)phenol]. By using these compounds having a phenolic hydroxyl group and an alcoholic hydroxyl group, it is possible to easily introduce the phenolic hydroxyl group into the urethane resin.

[0038] The polycarbonate diol preferably has a number average molecular weight of 200 to 5,000, but when the polycarbonate diol contains repeating units derived from a linear aliphatic diol and an alicyclic diol as constituent units and the copolymerization ratio of the linear aliphatic diol to the alicyclic diol is 3:7 to 7:3 in mass ratio, the polycarbonate diol preferably has a number average molecular weight of 400 to 2,000.

[0039] Examples of the bisphenol A alkylene oxide adducts include ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of bisphenol A.

[0040] Specific examples of the phosphorus-containing polyol include FC-450 (manufactured by Asahi Denka Kogyo Co., Ltd.), M-Ester (manufactured by Sanko Co., Ltd.), and M-Ester-HP (manufactured by Sanko Co., Ltd.) By using this phosphorus-containing polyol, a phosphorus compound can be introduced into the urethane resin.

[0041] Next, as the compound (c) having one alcoholic hydroxyl group, various conventionally known monohydroxy compounds can be used, and examples thereof include, but are not limited to, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, t-butanol, amyl alcohol, hexyl alcohol, octyl alcohol, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, cyclohexanedimethanol mono(meth)acrylate, caprolactone or alkylene oxide adducts of the above (meth)acrylates, glycerin di(meth)acrylate, trimethylol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, allyl alcohol, allyloxyethanol, glycolic acid, and hydroxypivalic acid.

[0042] The compound (c) having a phenolic hydroxyl group and one alcoholic hydroxyl group per molecule is used for the purpose of introducing a phenolic hydroxyl group into polyurethane, and also functions as an end-capping agent for polyurethane. In particular, a compound having one alcoholic hydroxyl group and a phenolic hydroxyl group per molecule that can react with isocyanate functions as a reaction terminator. Specific examples of such compound (c) include hydroxymethylphenol, hydroxymethylcresol, hydroxymethyl-di-t-butylphenol, p-hydroxyphenyl-2-methanol, p-hydroxyphenyl-3-propanol, p-hydroxyphenyl-4-butanol, hydroxyethylcresol, 2,6-dimethyl-4-hydroxymethylphenol, 2,4-dimethyl-6-hydroxymethylphenol, 2,3,6-trimethyl-4-hydroxymethylphenol, 2-cyclohexyl-4-hydroxymethyl-5-methylphenol, 4-methyl-6-hydroxymethylbenzene-1,2-diol, 4-(1,1-dihydroxymethyl)benzene-2-ol, 4-(1,1-dihydroxymethyl) ... Examples of the compound (c) include, but are not limited to, hydroxyalkylphenols or hydroxyalkylcresols such as (methylethyl)-6-hydroxymethylbenzene-1,2-diol; esters of phenols having a carboxyl group-containing substituent, such as hydroxybenzoic acid, hydroxyphenylbenzoic acid, or hydroxyphenoxybenzoic acid, with ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, etc.; monoethylene oxide adducts of bisphenols, monopropylene oxide adducts of bisphenols, p-hydroxyphenethyl alcohol, etc. These compounds (c) can be used alone or in combination of two or more.

[0043] The weight-average molecular weight of the carboxyl group-containing urethane resin (A) is preferably 500 to 100,000, and more preferably 8,000 to 50,000. Here, the weight-average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography. When the weight-average molecular weight of the carboxyl group-containing urethane resin (A) is 500 or more, the elongation, flexibility, and strength of the cured film are improved, and when it is less than 100,000, the resin is developable, has improved solubility, and does not have an excessively high viscosity after dissolution.

[0044] The acid value of the carboxyl group-containing urethane resin (B) is preferably in the range of 10 to 120 mgKOH / g, more preferably 20 to 80 mgKOH / g. An acid value of 10 mgKOH / g or more improves the reactivity with the thermosetting component and the heat resistance. On the other hand, an acid value of 120 mgKOH / g or less improves the alkali resistance and resist properties such as electrical properties of the cured film. The acid value of the resin is a value measured in accordance with JIS K5601-1-2-1:1999.

[0045] These carboxyl group-containing urethane resins (B) may be used alone or in combination.

[0046] When the total amount of the alkali-soluble polymer (A) and the carboxyl group-containing urethane resin (B) is taken as 100 parts by mass, the content of the alkali-soluble polymer (A) is 45 to 75 parts by mass, preferably 50 to 70 parts by mass, and the content of the carboxyl group-containing urethane resin (B) is 25 to 55 parts by mass, preferably 30 to 50 parts by mass, calculated as solids. By setting the blending ratio (content ratio) of the alkali-soluble polymer (A) to the carboxyl group-containing urethane resin (B) within the above range, it is possible to further improve developability and transparency, and also to improve adhesion to the base.

[0047] (Polymerizable Compound (C)) The polymerizable compound (C) has an ethylene oxide skeleton. The polymerizable compound (C) is represented, for example, by the following formula (1): １ -(CCO)n-R ２ ... (1) In formula (1), R １, R ２ are each independently a monovalent organic group having an unsaturated double bond, such as a (meth)acrylate group or a vinyl group. n represents the number of repeating ethylene oxide groups and is an integer of 1 or more. n is preferably 2 to 30.

[0048] Specific examples of the polymerizable compound (C) include ethoxylated bisphenol A dimethacrylate, polyether-modified (EO-modified) acrylate oligomer, and ethoxylated glycerin triacrylate.

[0049] When the total of the alkali-soluble polymer (A) and the carboxyl group-containing urethane resin (B) is taken as 100 parts by mass, the content of the polymerizable compound (C) is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, and particularly preferably 35 parts by mass or more. The upper limit of the content of the polymerizable compound (C) is not particularly limited as long as it does not impair the effects of the present invention, and is, for example, 60 parts by mass or less, 55 parts by mass or less, 50 parts by mass or less, or 45 parts by mass or less when the total of the alkali-soluble polymer (A) and the carboxyl group-containing urethane resin (B) is taken as 100 parts by mass.

[0050] (Other Components) The transparent resin composition of the present embodiment may contain a polymerization initiator. The polymerization initiator may be either a thermal polymerization initiator or a photopolymerization initiator, but a photopolymerization initiator is preferred.Examples of the photopolymerization initiator include benzoin and benzoin alkyl ethers such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether; acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, and 1,1-dichloroacetophenone; 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2- Aminoalkylphenones such as dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone and 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone; anthraquinones such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone and 1-chloroanthraquinone; 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, Thioxanthones such as 2-chlorothioxanthone and 2,4-diisopropylthioxanthone; ketals such as acetophenone dimethyl ketal and benzil dimethyl ketal; benzophenones such as 4,4'-bis(diethylamino)benzophenone; (2,6-dimethoxybenzoyl)-2,4,4-pentylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl-2,4,6-trimethylbenzoylphenylphosphine oxide, methyl ... oxime esters such as 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime), 9-ethyl-6-nitro-9H-carbazol-3-yl)(4-((1-methoxypropan-2-yl)oxy)-2-methylphenyl)methanone O-acetyloxime; various peroxides, and titanocene initiators.These may be used in combination with a photosensitizer such as N,N-dimethylaminobenzoic acid ethyl ester, N,N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, or tertiary amines such as triethylamine and triethanolamine. These photopolymerization initiators may be used alone or in combination of two or more.

[0051] The blending amount of the photopolymerization initiator other than the oxime esters is preferably 0.01 to 30 parts by mass, more preferably 0.5 to 28 parts by mass, and even more preferably 1.0 to 25 parts by mass, relative to 100 parts by mass of the total of the alkali-soluble polymer (A) and the carboxyl group-containing urethane resin (B) in the transparent resin composition of this embodiment. The blending amount of the oxime ester photopolymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.01 to 7.0 parts by mass, and even more preferably 0.01 to 5.0 parts by mass, relative to 100 parts by mass of the total of the alkali-soluble polymer (A) and the carboxyl group-containing urethane resin (B) in the transparent resin composition of this embodiment.

[0052] The transparent resin composition of the present embodiment may contain an epoxy resin as a thermosetting component. Examples of the epoxy resin include bifunctional epoxy resins such as bisphenol A type epoxy resins, hydrogenated bisphenol A type epoxy resins, brominated bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bixylenol type epoxy resins, biphenyl type epoxy resins, biphenol type epoxy resins, and trisphenol type epoxy resins. Examples of the polyfunctional epoxy resin include novolac type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, N-glycidyl type epoxy resins, bisphenol A novolac type epoxy resins, bixylenol type epoxy resins, biphenol novolac type epoxy resins, chelate type epoxy resins, glyoxal type epoxy resins, amino group-containing epoxy resins, rubber-modified epoxy resins, dicyclopentadiene phenolic type epoxy resins, diglycidyl phthalate resins, heterocyclic epoxy resins, tetraglycidylxylenoylethane resins, silicone-modified epoxy resins, and ε-caprolactone-modified epoxy resins. More preferred epoxy resins that readily yield highly transparent cured products include bisphenol A epoxy resins, hydrogenated bisphenol A epoxy resins, brominated bisphenol A epoxy resins, bisphenol F epoxy resins, bisphenol S epoxy resins, bixylenol epoxy resins, biphenyl epoxy resins, and biphenol epoxy resins. Specific examples include biphenyl novolac epoxy resin NC-3000 (manufactured by Nippon Kayaku Co., Ltd.), biphenyl epoxy resin YX-4000 (manufactured by Mitsubishi Chemical Corporation), hydrogenated bisphenol A epoxy resin YX-8034 (manufactured by Mitsubishi Chemical Corporation), bisphenol A epoxy resin JER-828 (manufactured by Mitsubishi Chemical Corporation), mixed resin ST6100 of bisphenol A epoxy and hydrogenated bisphenol A epoxy (manufactured by Nippon Steel Chemical & Material Co., Ltd.), and trisphenol epoxy resin VG-3101L (manufactured by Printec Co., Ltd.). The epoxy resin is preferably bifunctional or trifunctional.This can further enhance the transparency of the cured product obtained from the transparent resin composition. In order to impart flame retardancy, an epoxy resin having an atom of a halogen such as chlorine or bromine, or phosphorus introduced into its structure may be used.

[0053] The amount of epoxy resin blended is preferably 5 to 150 parts by mass, more preferably 10 to 80 parts by mass, and even more preferably 20 to 70 parts by mass, relative to 100 parts by mass of the total of the alkali-soluble polymer (A) and the carboxyl group-containing urethane resin (B). By blending the epoxy resin in an amount of 5 parts by mass or more, the strength of the cured film can be increased. On the other hand, by blending the epoxy resin in an amount of 150 parts by mass or less, the flexibility, transparency, environmental resistance, adhesion, and electrical properties can be improved.

[0054] The transparent resin composition of the present embodiment may contain a filler to the extent that the effect is not impaired. The filler can be used to improve the mechanical strength of a cured product of the transparent resin composition or to improve the coatability of the transparent resin composition.

[0055] Examples of fillers include metal oxides such as silica, alumina, and titanium oxide; metal hydroxides such as aluminum hydroxide and magnesium hydroxide; clay minerals such as talc and mica; fillers having a ferrovskite crystal structure such as barium titanate and strontium titanate; inorganic fillers such as boron nitride, aluminum borate, barium sulfate, and calcium carbonate may also be used; fluororesin fillers such as polytetrafluoroethylene (PTFE), tetrafluoroethylene / ethylene copolymer (ETFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), and polyvinyl fluoride (PVF); and organic fillers such as hydrocarbon resin fillers such as cycloolefin polymer (COP) and cycloolefin copolymer (COC). One type of filler may be used alone, or two or more types may be used in combination.

[0056] Among the above fillers, silica is preferably contained from the viewpoint of improving the coatability of the transparent resin composition. From the viewpoint of transparency, the silica used preferably has an average particle size of 1 to 100 nm, and more preferably an average particle size of 1 to 50 nm. Examples of such silica include AEROSIL 90, AEROSIL 130, AEROSIL 150, AEROSIL 200, AEROSIL 225, AEROSIL 300, AEROSIL 380, AEROSIL OX50, AEROSIL TT600, AEROSIL R104, AEROSIL R106, AEROSIL R202, AEROSIL R711, AEROSIL R805, AEROSIL R812, AEROSIL R816, AEROSIL R972, AEROSIL R974, AEROSIL R7200, AEROSIL R8200, AEROSIL R9200 (manufactured by Nippon Aerosil Co., Ltd.), and the like.

[0057] When the transparent resin composition of the present embodiment contains a filler, the content of the filler is preferably 1 to 20 parts by mass, and more preferably 3 to 20 parts by mass, relative to 100 parts by mass of the total of the alkali-soluble polymer (A) and the carboxyl group-containing urethane resin (B) in the transparent resin composition. When the content of the filler is within the above range, the transparent resin composition can be made to have excellent coatability while maintaining the transparency of the transparent resin composition and the cured product thereof.

[0058] The transparent resin composition of the present embodiment may contain an organic solvent. The organic solvent can be used to easily dissolve or disperse each component in the transparent resin composition or to adjust the viscosity to a level suitable for coating.

[0059] Examples of organic solvents include toluene, xylene, ethylbenzene, nitrobenzene, cyclohexane, isophorone, diethylene glycol dimethyl ether, ethylene glycol diethyl ether, carbitol acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, dipropylene glycol methyl ether acetate, diethylene glycol ethyl ether acetate, methyl methoxypropionate, ethyl methoxypropionate, methyl ethoxypropionate, ethyl ethoxypropionate, ethyl acetate, n-butyl acetate, isoamyl acetate, ethyl lactate, acetone, methyl ethyl ketone, cyclohexanone, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, γ-butyrolactone, dimethyl sulfoxide, chloroform, and methylene chloride. The amount of organic solvent blended can be appropriately determined depending on the desired viscosity.

[0060] The transparent resin composition of the present embodiment may contain, as other components, various additives such as an antifoaming agent, an adhesion imparting agent or a leveling agent, known and commonly used polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, pyrogallol, tertiary butyl catechol or phenothiazine, a coupling agent, a dispersant, a flame retardant, etc., within the scope of not impairing the effects of the present invention.

[0061] (Dry Film) The dry film according to the embodiment has a resin layer obtained by applying the transparent resin composition of the above-described form to at least one surface of a first film (substrate film) and then drying the applied resin layer. When used, the resin layer is laminated to a substrate or board so as to be in contact with the substrate or board.

[0062] The dry film according to the embodiment can be produced by uniformly applying the transparent resin composition of the above-described form to a first film (substrate film) by an appropriate method such as a blade coater, lip coater, comma coater, or film coater, drying the applied layer to form the resin layer, and preferably laminating a second film (a so-called cover film (protective film)) thereon. The second film and the first film may be made of the same film material or different films.

[0063] The film materials used for the first film and the second film can be any of those known to be used for dry films. The first film can be a thermoplastic film, such as a polyester film such as polyethylene terephthalate, having a thickness of 2 to 150 μm. The second film can be a polyethylene film, a polypropylene film, or the like. However, it is preferable that the film used for the second film has a weaker adhesive strength with the resin layer than the first film.

[0064] The thickness of the resin layer in the dry film according to the embodiment is preferably 200 μm or less, more preferably in the range of 5 to 50 μm.

[0065] (Cured Product) The cured product according to the embodiment can be obtained by curing the transparent resin composition or dry film according to the above-described embodiment in a predetermined step. The cured product, i.e., a patterned cured film, can be produced by a known or commonly used method, for example, as follows.

[0066] In step 1, a resin layer is obtained by applying a transparent resin composition to a substrate and drying it. When a dry film is used, the resin layer is formed on the substrate by laminating it onto the substrate using a laminator or the like so that the resin layer comes into contact with the substrate. Methods for applying the transparent resin composition to the substrate include conventional methods for applying transparent resin compositions, such as coating with a spin coater, bar coater, blade coater, curtain coater, or screen printer, spray coating with a spray coater, and even inkjet printing. Furthermore, laminating the dry film onto the substrate is preferably performed under pressure and heat using a vacuum laminator or the like. By using such a vacuum laminator, even if a circuit-formed substrate is used and the circuit board surface is uneven, the dry film adheres to the circuit board, preventing the introduction of air bubbles and improving the filling of recesses on the substrate surface. The pressure conditions are preferably approximately 0.1 to 2.0 MPa, and the heating conditions are preferably 40 to 120°C. Drying methods used after application of the transparent resin composition include air drying, heat drying using an oven or hot plate, vacuum drying, and IR dryers. Drying conditions are not particularly limited, but natural drying, air drying, or heat drying can be performed at 60 to 130°C for 1 to 30 minutes. The substrate on which the resin layer is formed is not particularly limited, and examples include printed wiring boards and flexible printed wiring boards with pre-formed circuits using copper or the like, as well as copper-clad laminates for high-frequency circuits made of materials such as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven cloth epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, fluororesin / polyethylene / polyphenylene ether, polyphenylene oxide / cyanate, and the like, including copper-clad laminates of all grades (such as FR-4), as well as metal substrates, polyimide films, cycloolefin polymer films, polyethylene terephthalate films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, and wafer plates.

[0067] Next, in step 2, the resin layer is irradiated (exposed) with light through a patterned photomask or directly in a pattern. In the method of laminating a dry film, the first film is peeled off from the dry film after exposure. The exposed resin layer may be exposed by peeling off the first film from the dry film before exposure, provided that the properties are not impaired. For exposure, any device equipped with a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a mercury short arc lamp, or the like, and capable of irradiating ultraviolet light in the range of 350 to 450 nm may be used. Furthermore, a direct imaging device (e.g., a laser direct imaging device that draws an image directly with a laser based on CAD data from a computer) may also be used. The lamp or laser light source of the direct imaging device may have a maximum wavelength in the range of 350 to 450 nm. The exposure dose varies depending on the film thickness, etc., but is generally 10 to 1,000 mJ / cm. ２ , preferably 20 to 900 mJ / cm ２ The range may be:

[0068] Next, in step 3, the exposed resin layer is treated with a developer, thereby removing the unexposed portions of the resin, and forming a patterned film of the transparent resin composition according to the embodiment.

[0069] The development method can be selected from dipping, showering, spraying, brushing, and the like. Examples of the developer include aqueous solutions of inorganic alkalis such as sodium hydroxide, sodium carbonate, sodium silicate, and aqueous ammonia; organic amines such as ethylamine, diethylamine, triethylamine, and triethanolamine; and quaternary ammonium salts such as tetramethylammonium hydroxide and tetrabutylammonium hydroxide. If necessary, an appropriate amount of a water-soluble organic solvent or surfactant such as methanol, ethanol, or isopropyl alcohol may be added to the developer. Thereafter, if necessary, the coating film is washed with a rinse solution to obtain a patterned film. As the rinse solution, distilled water, methanol, ethanol, isopropyl alcohol, and the like may be used alone or in combination. The above-mentioned solvents may also be used as the developer.

[0070] Furthermore, if necessary, in step 4, the pattern film may be irradiated with active energy rays and then heat-cured, or may be irradiated with active energy rays after heat-curing, or may be heat-cured alone to perform final finish curing (main curing). The heating temperature is not particularly limited, but may be, for example, heating at 100 to 220°C for about 30 to 120 minutes. The atmosphere (gas) used in this step may be air, or an inert gas such as nitrogen or argon.

[0071] The cured product according to the embodiment preferably has a transmittance of 85% or more as measured under the following conditions. This allows the cured product to be suitably used as an insulating protective film for transparent electronic components. (Conditions) A transparent resin composition is applied to a first film so that the film thickness after drying is 8 μm, and the film is heated and dried in a hot air dryer at 80°C for 30 minutes to form a resin layer. A COP film having a film thickness of 50 μm is attached to the exposed surface of the resin layer so that it is in contact with the film, and lamination is performed. After solid exposure using a parallel light exposure machine, the first film is peeled off, and the film is dried in a 1% Na2CO3 solution at 30°C. ３The coating is developed for 30 seconds using an aqueous solution at a spray pressure of 0.1 MPa. The coating is then cured by heating at 130°C for 60 minutes in a hot air circulation drying oven, yielding a substrate for transmittance measurement with a cured product having a film thickness of 8 μm. The transmittance of the resulting cured product in the 380-780 nm range is measured using a UV-visible spectrophotometer.

[0072] (Electronic Component) An electronic component according to an embodiment has the cured product of the above-described aspect. The cured product not only has excellent transparency, but is also suitable for microfabrication and has good adhesion, making it suitable for use as an insulating protective film for transparent electronic components. Examples of transparent electronic components include transparent antennas and transparent displays. More specifically, the cured product of the above-described aspect is suitable for use as a surface protective film for transparent electronic components, an interlayer insulating film, an insulating film for rewiring, a protective film for flip-chip devices, a protective film for devices with bump structures, an interlayer insulating film for multilayer circuits, an insulating material for passive components, and a protective film for printed wiring boards such as a solder resist or coverlay film.

[0073] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted.

[0074] EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these.

[0075] The transparent resin compositions of each Example and Comparative Example were prepared by blending the components shown in Tables 1 and 2, mixing them with a stirrer, and dispersing them with a roll or bead mill. The values ​​in the tables indicate parts by mass of the solid content.

[0076] The details of Synthesis Examples 1 to 3 shown in Tables 1 and 2 are as follows.

[0077] Synthesis Example 1: Synthesis of an alkali-soluble polymer having cyclohexyl groups and carboxy groups. 223.8 g (2.6 mol) of methacrylic acid, 100.1 g (1.0 mol) of methyl methacrylate, 246.7 g (1.6 mol) of cyclohexyl acrylate, 1400 g of dipropylene glycol methyl ether, and 16.4 g (0.1 mol) of azobisisobutyronitrile were added to a four-neck flask equipped with a reflux condenser, a thermometer, a glass tube for nitrogen substitution, and a stirrer. The mixture was heated at 75°C for 5 hours under a nitrogen stream to allow the polymerization reaction to proceed. 17.0 g (0.07 mol) of triphenylphosphine was added, followed by the addition of 156.4 g (1.1 mol) of glycidyl methyl methacrylate, and the mixture was heated at 90 to 100°C for 6 hours to add acrylic groups. Thereafter, triphenylphosphine was deactivated by air bubbling to obtain an alkali-soluble polymer solution having a cyclohexyl group and a carboxyl group (solid acid value: 110 mg KOH / g, solid concentration: 35% by mass, molecular weight Mw: 15,000).

[0078] Synthesis Example 2 Synthesis of Urethane Resin Using Compound Having Isocyanate Group and Cyclohexyl Group Not Directly Bonded to Aromatic Ring Into a reaction vessel equipped with a stirrer, a thermometer, and a condenser, 360 g (0.45 mol) of polycarbonate diol (number average molecular weight 800) derived from 1,5-pentanediol and 1,6-hexanediol as a compound having two or more alcoholic hydroxyl groups, 81.4 g (0.55 mol) of dimethylolbutanoic acid, and 22.1 g (0.16 mol) of hydroxyphenylethyl alcohol as a compound having one alcoholic hydroxyl group and one or more phenolic hydroxyl groups in one molecule were placed. Next, 283.0 g (1.08 mol) of dicyclohexylmethane-4,4-diisocyanate, a compound having an isocyanate group not directly bonded to an aromatic ring and a cyclohexyl group, was added, and the mixture was heated to 60°C with stirring, then stopped. When the temperature inside the reaction vessel began to drop, the mixture was heated again at 80°C and continued stirring. The reaction was terminated when the disappearance of the isocyanate group absorption spectrum (2280 cm-1) in the infrared absorption spectrum was confirmed. Carbitol acetate was then added to achieve a solids content of 50 wt%, yielding a urethane resin using a compound having an isocyanate group and a cyclohexyl group not directly bonded to an aromatic ring. The acid value of the solids of the resulting urethane resin using a compound having an isocyanate group and a cyclohexyl group not directly bonded to an aromatic ring was 41.3 mgKOH / g.

[0079] Synthesis Example 3 Synthesis of urethane resin using a compound having an isocyanate group not directly bonded to an aromatic ring but no cyclohexyl group Into a reaction vessel equipped with a stirrer, a thermometer, and a condenser, 360 g (0.45 mol) of polycarbonate diol (number average molecular weight 800) derived from 1,5-pentanediol and 1,6-hexanediol as a compound having two or more alcoholic hydroxyl groups, 81.4 g (0.55 mol) of dimethylolbutanoic acid, and 22.1 g (0.16 mol) of hydroxyphenylethyl alcohol as a compound having one alcoholic hydroxyl group and one or more phenolic hydroxyl groups in one molecule were placed. Next, 200.9 g (1.08 mol) of trimethylhexamethylene diisocyanate was added as a compound having an isocyanate group not directly bonded to an aromatic ring but not having a cyclohexyl group, and the mixture was heated to 60°C with stirring and stopped. When the temperature in the reaction vessel began to drop, the mixture was heated again and continued stirring at 80°C. The absorption spectrum of the isocyanate group (2280 cm) was measured by infrared absorption spectroscopy. －１ The reaction was terminated after confirming that the hydroxyl group had disappeared. Carbitol acetate was then added so that the solids content was 50 wt %, yielding a urethane resin using a compound having an isocyanate group not directly bonded to an aromatic ring but not a cyclohexyl group. The acid value of the solids of the resulting urethane resin using a compound having an isocyanate group not directly bonded to an aromatic ring but not a cyclohexyl group was 48.8 mg KOH / g.

[0080] Synthesis Example 4: Synthesis of urethane resin using a compound having an isocyanate group directly bonded to an aromatic ring Into a reaction vessel equipped with a stirrer, a thermometer, and a condenser, 360 g (0.45 mol) of a polycarbonate diol (number average molecular weight 800) derived from 1,5-pentanediol and 1,6-hexanediol as a compound having two or more alcoholic hydroxyl groups, 81.4 g (0.55 mol) of dimethylolbutanoic acid, and 11.8 g (0.16 mol) of n-butanol as a molecular weight modifier (reaction terminator) were added. Next, 187.9 g (1.08 mol) of tolylene diisocyanate as a compound having an isocyanate group directly bonded to an aromatic ring was added, and the mixture was heated to 60°C with stirring and stopped. When the temperature in the reaction vessel began to decrease, the mixture was heated again and continued stirring at 80°C. The absorption spectrum of the isocyanate group (2280 cm) was measured by infrared absorption spectroscopy. －１ The reaction was terminated after confirming that the carboxyl group-containing urethane resin had disappeared. Carbitol acetate was then added to adjust the solid content to 50 wt %, yielding a viscous liquid carboxyl group-containing urethane resin (varnish D) containing a diluent. The acid value of the solid content of the resulting carboxyl group-containing urethane resin was 49.5 mg KOH / g.

[0081] <Preparation of Dry Film for Evaluation> The transparent resin composition of each Example and Comparative Example was applied to a polyethylene film (E5041, manufactured by Toyobo Co., Ltd.) measuring 95 mm x 150 mm and 25 μm thick so that the film thickness after drying would be 8 μm, and the applied film was heated and dried in a hot air dryer at 80°C for 30 minutes to form a resin layer. A biaxially oriented polypropylene film (MA-411, manufactured by Oji F-Tex Co., Ltd.) measuring 95 mm x 150 mm and 15 μm thick was then laminated onto the resin layer to obtain a dry film for evaluation. When the transparent resin composition of Example 13 was used, it was confirmed that the coatability onto the polyethylene film was better than in the other Examples.

[0082] <Developability> The biaxially stretched polypropylene film was peeled off from each dry film prepared in <Preparation of dry film for evaluation>, and the exposed resin layer side was attached to a COP film (ZEONER ZF14, manufactured by Zeon Corporation) having a size of 90 mm × 150 mm and a thickness of 50 μm (haze value 1.8%) so that the film was in contact with the substrate. The dry film was then laminated onto the substrate using a two-chamber vacuum laminator (manufactured by Nikko Materials Co., Ltd., CVP-300) using only the first chamber under conditions of a temperature of 70°C, a vacuuming time of 20 seconds, a pressure of 0.4 MPa, and a pressurization time of 40 seconds, and the laminate was allowed to cool to room temperature to prepare a substrate for developing property evaluation.

[0083] The substrate for evaluating developability prepared by the above method was subjected to a developer (1 mass % Na ２ CO ３ Development was carried out by spraying a solution of 100% COP film (aqueous solution) at a spray pressure of 0.1 MPa for 30 seconds. The haze value of the COP substrate after development was measured using a haze meter (NDH-7000II manufactured by Nippon Denshoku Industries Co., Ltd.) to confirm the presence or absence of residue. The evaluation results are shown in Tables 1 and 2. The haze value of the COP substrate alone was 1.8%. A+ (Excellent): The haze value of the COP substrate was less than 2.5%. A (Good): The haze value of the COP substrate was 2.5% or more and less than 3.0%. B (Fair): The haze value of the COP substrate was 3.0% or more and less than 3.5%. C (Fail): The haze value of the COP substrate was 3.5% or more.

[0084] <Transmittance Measurement> The biaxially stretched polypropylene film of the dry film prepared in <Preparation of Dry Film for Evaluation> was peeled off, and the exposed resin layer side was attached so that it was in contact with a COP film (ZEONER ZF14, manufactured by Zeon Corporation, transmittance 90% or more) measuring 95 mm x 150 mm and 50 μm thick. The COP film and dry film were laminated using a two-chamber vacuum laminator (manufactured by Nikko Materials Co., Ltd., CVP-300) using only the first chamber under conditions of a temperature of 70°C, a vacuum time of 20 seconds, a pressure of 0.4 MPa, and a pressure time of 40 seconds. A parallel light exposure machine (EXP2960, manufactured by Oak Manufacturing Co., Ltd.) was used to place a Kodak Step Tablet No. 2 on the dry film and solid exposure was performed at an optimal exposure amount so that the number of steps after development would be 5. After peeling off the polyethylene film, the film was exposed to 1% NaCl at 30°C. ２ CO ３ The coating was developed for 30 seconds using an aqueous solution at a spray pressure of 0.1 MPa. The coating was then thermally cured by heating at 130°C for 60 minutes in a hot air circulation drying oven, yielding a substrate for transmittance measurement on which a cured product with a film thickness of 8 μm had been formed. The transmittance of the resulting cured product in the 380-780 nm range was measured using a UV-visible spectrophotometer (V-570, manufactured by JASCO Corporation).

[0085] The obtained transmittance was evaluated according to the following criteria: A+ (excellent): more than 90% A (good): 85% to 90% B (passable): 70% to less than 85% C (unacceptable): less than 70%

[0086] <Haze Measurement> The biaxially stretched polypropylene film of the dry film prepared in <Preparation of Dry Film for Evaluation> was peeled off, and the exposed resin layer side was attached so that it was in contact with a COP film (ZEONER ZF14, manufactured by Zeon Corporation) measuring 95 mm x 150 mm and 50 μm thick. Using a two-chamber vacuum laminator (manufactured by Nikko Materials Co., Ltd., CVP-300), the COP film and dry film were laminated using only the first chamber under conditions of a temperature of 70°C, a vacuum time of 20 seconds, a pressure of 0.4 MPa, and a pressure time of 40 seconds. A parallel light exposure machine (EXP2960, manufactured by Oak Manufacturing Co., Ltd.) was used to place a Kodak Step Tablet No. 2 on the dry film and solid exposure was performed at an optimal exposure amount so that the number of steps after development would be 5. After peeling off the polyethylene film, the film was exposed to 1% NaCl at 30°C. ２ CO ３ The coating was developed for 30 seconds using an aqueous solution at a spray pressure of 0.1 MPa. The coating was then heated in a hot air circulation drying oven at 130°C for 60 minutes for thermal curing, resulting in a substrate for haze measurement on which a cured product with a film thickness of 8 μm had been formed. The haze value of the substrate for haze measurement was measured using a haze meter (NDH7000II manufactured by Nippon Denshoku Industries Co., Ltd.). Based on the obtained haze value, evaluation was performed according to the following criteria. The results are shown in Tables 1 and 2. A+ (Excellent): Less than 4.0% A (Good): 4.0% or more and less than 4.5% B (Fair): 4.5% or more and less than 7.0% C (Fail): 7.0% or more

[0087] <Transmittance Measurement After Constant Temperature and Humidity Test> The COP film having a film thickness of 8 μm and a cured product formed thereon, which was used for the transmittance measurement, was left standing for 500 hours under conditions of 85° C. and 85% RH, and then the transmittance was measured and evaluated as described above.

[0088] <Haze after constant temperature and humidity test> The COP film having the 8 μm thick cured product formed thereon and used for haze measurement was allowed to stand at 85° C. and 85% RH for 500 hours, and then the haze was measured and evaluated as described above.

[0089] <COP Adhesion> The biaxially stretched polypropylene film of the dry film prepared in <Preparation of Dry Film for Evaluation> was peeled off, and the exposed resin layer side was attached so that it was in contact with a COP film (ZEONEX ZF14, manufactured by Zeon Corporation) measuring 95 mm x 150 mm and 50 μm thick. The COP film and dry film were then laminated using a two-chamber vacuum laminator (manufactured by Nikko Materials Co., Ltd., CVP-300) using only the first chamber under conditions of a temperature of 70°C, a vacuum time of 20 seconds, a pressure of 0.4 MPa, and a pressure time of 40 seconds. A parallel light exposure machine (EXP2960, manufactured by Oak Manufacturing Co., Ltd.) was used to place a Kodak Step Tablet No. 2 on the dry film and solid exposure was performed at an optimal exposure amount so that the number of steps after development would be 5. After peeling off the polyethylene film, the film was exposed to 1% NaCl at 30°C. ２ CO ３ The coating was developed for 30 seconds using an aqueous solution at a spray pressure of 0.1 MPa. The coating was then heated in a hot air circulation drying oven at 130°C for 60 minutes for thermal curing, yielding a substrate for evaluating COP adhesion on which a permanently cured product with a film thickness of 8 µm had been formed. For each evaluation substrate obtained above, a 1 mm ２ One hundred grids (10 x 10) were made, and transparent adhesive tape (manufactured by Nichiban Co., Ltd., width: 18 mm) was completely adhered to all of the grids. Immediately, one end of the tape was held perpendicular to the COP film and instantly pulled away. The tape was observed at a magnification of 500x using an optical microscope (VHX-7000 manufactured by Keyence Corporation), and the number of grids that remained without being completely peeled off was counted. The adhesion of the cured product was evaluated according to the following criteria, and the evaluation results are shown in Tables 1 and 2. A+ (Excellent): 100% of the grids remained. A (Good): 95% or more but less than 100% of the grids remained. B (Fair): 90% or more but less than 95% of the grids remained. C (Unacceptable): Less than 90% of the grids remained.

[0090] <Adhesion on Cu> The biaxially stretched polypropylene film of the dry film prepared in <Preparation of Dry Film for Evaluation> was peeled off, and the exposed resin layer side was attached so as to come into contact with a 1.8 mm thick copper-clad laminate from which the oxide film had been removed using a 5% aqueous sulfuric acid solution. Using a two-chamber vacuum laminator (Nikko Materials Co., Ltd., CVP-300), the copper-clad laminate and the dry film were laminated using only the first chamber under conditions of a temperature of 70°C, a vacuum time of 20 seconds, a pressure of 0.4 MPa, and a pressure time of 40 seconds. A parallel light exposure machine (EXP2960, Oak Manufacturing Co., Ltd.) was used to place a Kodak Step Tablet No. 2 on the dry film and perform solid exposure at an optimal exposure amount so that the number of steps after development would be 5. After peeling off the polyethylene film, the film was exposed to 1% Na2CO3 at 30°C. ３ The coating was developed for 30 seconds using an aqueous solution at a spray pressure of 0.1 MPa. The coating was then cured by heating in a hot air circulation drying oven at 130°C for 60 minutes, yielding a substrate for evaluation of adhesion on Cu on which a fully cured product with a film thickness of 8 µm had been formed. For each of the obtained evaluation substrates, a 1 mm thick film was applied to the fully cured product on the substrate in accordance with JIS K5400. ２ One hundred grids (10 x 10) were made, and transparent adhesive tape (manufactured by Nichiban Co., Ltd., width: 18 mm) was completely adhered to all of the grids. Immediately, one end of the tape was held perpendicular to the copper-clad laminate and instantly pulled away. The tape was observed at a measurement magnification of 500x using an optical microscope (VHX-7000 manufactured by Keyence Corporation), and the number of grids that remained without being completely peeled off was counted. The adhesion of the cured product was evaluated according to the following criteria, and the evaluation results are shown in Tables 1 and 2. A+ (Excellent): 100% of the grids remained. A (Good): 95% or more but less than 100% of the grids remained. B (Acceptable): 90% or more but less than 95% of the grids remained. C (Unacceptable): Less than 90% of the grids remained.

[0091]

[0092]

[0093] The transparent resin composition of the present invention has excellent transparency, developability, and adhesion, and can therefore be used to form protective films for transparent electronic components. CROSS-REFERENCE TO RELATED APPLICATIONS

[0094] This application claims priority based on Japanese Patent Application No. 2023-187236, filed with the Japan Patent Office on October 31, 2023, the entire disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A transparent resin composition comprising: (A) an alkali-soluble polymer containing a cyclohexyl group and a carboxyl group; (B) a carboxyl group-containing urethane resin obtained using a compound having an isocyanate group that is not directly bonded to an aromatic ring; and (C) a polymerizable compound having an ethylene oxide skeleton, wherein the content of the alkali-soluble polymer (A) is 45 to 75 parts by mass, calculated as solid content, when the total of the alkali-soluble polymer (A) and the carboxyl group-containing urethane resin (B) is 100 parts by mass.

2. The transparent resin composition according to claim 1, wherein the alkali-soluble polymer (A) has an ethylenically unsaturated group, and the polymerizable compound (C) has an unsaturated double bond.

3. The transparent resin composition according to claim 1, wherein the content of the polymerizable compound (C) is 20 parts by mass or more, calculated as solid content, when the total of the alkali-soluble polymer (A) and the carboxyl group-containing urethane resin (B) is 100 parts by mass.

4. The transparent resin composition according to claim 1, further comprising a polymerization initiator.

5. The transparent resin composition according to claim 1 or 2, which contains an epoxy resin.

6. A dry film obtained by applying the transparent resin composition according to claim 1 to a first film.

7. A cured product obtained by using the transparent resin composition according to claim 1 or the dry film according to claim 6.

8. The cured product according to claim 7, which has a transmittance of 85% or more as measured under the following conditions: (Conditions) The transparent resin composition is applied onto a first film so that the film thickness after drying is 8 μm, and the composition is dried by heating in a hot air dryer at 80° C. for 30 minutes to form a resin layer. A COP having a film thickness of 50 μm is attached to the exposed surface of the resin layer to perform lamination. After solid exposure using a parallel light exposure machine, the first film is peeled off, and the composition is exposed to 1% NaCl at 30° C. ２ CO ３ The coating is developed for 30 seconds using an aqueous solution at a spray pressure of 0.1 MPa. The coating is then cured by heating in a hot air circulation drying oven at 130°C for 60 minutes to obtain a substrate for transmittance measurement having a cured product with a film thickness of 8 μm. The transmittance of the resulting cured product at 380 to 780 nm is measured using an ultraviolet-visible spectrophotometer.

9. An electronic component having the cured product according to claim 7, which is used as an insulating protective film for a transparent electronic component.

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