Resin composition, dry film, cured product, and light emitting element mounted substrate

Abstract

The present invention provides a resin composition with which it is possible to produce a white solder resist that has a high reflectance and is less likely to produce defective products. One embodiment of the present invention is a resin composition. The resin composition contains an alkali-soluble polymer (A) that contains a cyclohexyl group and a carboxyl group, a urethane polymer (B), a compound (C) that contains a thiol group, and a white pigment (D).

Description

Resin composition, dry film, cured product, and light-emitting element-mounting substrate

[0001] The present invention relates to a resin composition, a dry film, a cured product, and a light-emitting element mounting substrate.

[0002] White solder resist is sometimes used for displays. By using white solder resist as a solder resist, it not only functions as a permanent protective film for circuits, which is required of regular solder resist, but also increases the reflectivity when LEDs and other devices are mounted, thereby enabling increased brightness.

[0003] For example, Patent Document 1 discloses a technique for producing a white solder resist using a resin composition containing cyclohexyl methacrylate as a copolymer raw material and also containing titanium oxide or the like.

[0004] Japanese Patent Application Publication No. 11-087927

[0005] However, it has been found that when attempting to achieve a high reflectance with the white solder resist according to the prior art, defective products are likely to occur.

[0006] Therefore, an object of the present invention is to provide a resin composition that can be used to produce a white solder resist that has high reflectance and is less likely to produce defective products.

[0007] The present inventors have found that the above-mentioned problems can be solved by combining specific components, and have completed the present invention.

[0008] One aspect of the present invention is a resin composition, which contains (A) an alkali-soluble polymer containing a cyclohexyl group and a carboxyl group, (B) a urethane polymer, (C) a compound containing a thiol group, and (D) a white pigment.

[0009] The white pigment (D) preferably contains titanium oxide. The urethane polymer (B) preferably contains a carboxyl group. When the total of the alkali-soluble polymer (A), the urethane polymer (B), and the compound (C) is taken as 100 parts by mass, the content of the white pigment (D) is preferably 200 to 500 parts by mass, calculated as solid content. The resin composition preferably contains a polymerization initiator.

[0010] Another embodiment of the present invention is a dry film obtained by applying the resin composition to a first film.

[0011] Yet another embodiment of the present invention is a cured product obtained using the resin composition or the dry film.

[0012] Yet another aspect of the present invention is a light-emitting element mounting substrate having the cured product.

[0013] According to the present invention, there is provided a resin composition that can be used to produce a white solder resist that has high reflectance and is less likely to produce defective products.

[0014] FIG. 1 is a conceptual top view of a portion of a light-emitting element mounting substrate.

[0015] In the present specification, when isomers exist in the compounds described, all possible isomers can be used in the present invention unless otherwise specified.

[0016] In this specification, when the upper and lower limits of a numerical range are separately stated, all combinations of each lower limit and each upper limit are considered to be substantially stated within a consistent range.

[0017] In this specification, unless otherwise specified, various measurements are carried out at room temperature (25° C.).

[0018] In this specification, the number average molecular weight and weight average molecular weight are values ​​measured by gel permeation chromatography (GPC) and converted using a calibration curve prepared using standard polystyrene.

[0019] In this specification, there may be cases where the components contained in the resin composition and the components contained in the resin layer or the like, which is a dried coating film of the resin composition, are not distinguished from each other when describing the components.

[0020] In this specification, "(meth)acrylic" is meant to encompass both "acrylic" and "methacrylic", and "(meth)acrylate" is meant to encompass both "acrylate" and "methacrylate".

[0021] In this specification, the acid value is a value calculated by dissolving a sample in a titration solvent prepared by mixing xylene and dimethylformamide in a mass ratio of 1:1, titrating the sample with a 0.1 mol / L potassium hydroxide ethanol solution by potentiometric titration, and calculating the amount of potassium hydroxide solution titrated up to the end point, with the inflection point on the titration curve being the end point.

[0022] The components and methods of use / applications of the resin composition according to the present disclosure will be described below.

[0023] <<<Components of Resin Composition>>> The resin composition according to the present disclosure preferably contains an alkali-soluble polymer (A) containing a cyclohexyl group and a carboxyl group, a urethane polymer (B), a compound (C) containing a thiol group (hereinafter referred to as thiol group-containing compound (C)), and a white pigment (D). The resin composition according to the present disclosure preferably contains a thermosetting resin (E). The resin composition according to the present disclosure preferably contains a polymerization initiator (F). The resin composition according to the present disclosure may contain another component (G). Each component will be described below.

[0024] <<Alkali-Soluble Polymer (A)>> The alkali-soluble polymer (A) is not particularly limited as long as it is a polymer containing a cyclohexyl group and a carboxyl group.

[0025] Examples of the alkali-soluble polymer (A) include a copolymer of a monomer containing 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 monomer containing a cyclohexyl group-containing monomer and a carboxyl group-containing monomer.

[0026] 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, 1,4-cyclohexanedimethanol mono(meth)acrylate, and 3,4-epoxycyclohexyl (meth)acrylate.

[0027] The carboxyl group-containing monomer is not particularly limited, and examples thereof include compounds containing a carboxyl group and a (meth)acryloyl group, such as (meth)acrylic acid, carboxyethyl (meth)acrylate, mono(2-(meth)acryloyloxyethyl) succinate, and monohydroxyethyl (meth)acrylate phthalate.

[0028] 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 resolution and reflectance.

[0029] In this case, the monomers used in copolymerizing the alkali-soluble polymer (A) may contain monomers (other monomers) other than the monomer having a cyclohexyl group and the monomer containing a carboxyl group.

[0030] The other monomers are not particularly limited, and examples thereof include (meth)acrylates that do not have a cyclohexyl group, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, lauryl (meth)acrylate, 2-methylbutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate.

[0031] The ratio of the other monomers to all the monomers constituting the alkali-soluble polymer (A) is, for example, 50 mol % or less, 30 mol % or less, 25 mol % or less, or 20 mol % or less. The lower limit of the ratio of the other monomers is, for example, 1 mol %, 2 mol %, 5 mol %, or 10 mol %.

[0032] 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.

[0033] 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.

[0034] The alkali-soluble polymer (A) may be used alone or in combination of two or more.

[0035] 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). By setting the acid value of the alkali-soluble polymer (A) within this range, it becomes easier to obtain a cured product that has excellent developability, resolution, and reflectance.

[0036] 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 500 (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 developability, resolution, and reflectance.

[0037] 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 excellent in various performances.

[0038] 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 excellent in various performances.

[0039] The weight average molecular weight of the alkali-soluble polymer (A) 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. By setting the weight average molecular weight of the alkali-soluble polymer (A) within this range, it becomes easier to obtain a cured product that is excellent in various performances.

[0040] The content of the alkali-soluble polymer (A) in the resin composition is preferably 5 mass% or more, 8 mass% or more, or 10 mass% or more, based on the total mass of the solid content of the resin composition excluding the white pigment, and is preferably 50 mass% or less, 45 mass% or less, or 40 mass% or less.

[0041] <<Urethane Polymer (B)>> The urethane polymer (B) is, for example, a reaction product of a polyol having two or more hydroxyl groups per molecule and a polyisocyanate having two or more isocyanate groups per molecule.

[0042] The urethane polymer (B) may be any known urethane polymer and is not particularly limited. The urethane polymer (B) is preferably a carboxyl group-containing urethane polymer (hereinafter referred to as a carboxyl group-containing urethane resin). The carboxyl group-containing urethane resin preferably used as the urethane polymer (B) will be described in detail below.

[0043] The carboxyl group-containing urethane resin is preferably obtained using a compound having an isocyanate group that is not directly bonded to an aromatic ring. By including the carboxyl group-containing urethane resin, the resin composition improves adhesion to the substrate and developability. The carboxyl group-containing urethane resin 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 of its excellent photocurability and development resistance.

[0044] Specifically, the carboxyl group-containing urethane resin 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.

[0045] For example, in the case of the preferred urethane resin, the carboxyl group-containing urethane resin 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 in one molecule, and a compound (c) having one alcoholic hydroxyl group in one 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 in one molecule, followed by reaction with the compound (c) having one alcoholic hydroxyl group in one 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.

[0046] 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.

[0047] 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 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.

[0048] Next, as the compound (b) having two or more alcoholic hydroxyl groups, various conventionally known polyols can be used, and are not limited to a specific compound, 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] Examples of the bisphenol A alkylene oxide adducts include ethylene oxide adducts, propylene oxide adducts, and butylene oxide adducts of bisphenol A.

[0056] Specific examples of the phosphorus-containing polyol include FC-450 (manufactured by Asahi Denka Kogyo Co., Ltd.), M-Ester (manufactured by Sankosha Co., Ltd.), M-Ester-HP (manufactured by Sankosha Co., Ltd.), etc. By using this phosphorus-containing polyol, a phosphorus compound can be introduced into the urethane resin, thereby imparting flame retardancy.

[0057] 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.

[0058] 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.

[0059] The weight-average molecular weight of the carboxyl group-containing urethane resin 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 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.

[0060] The acid value of the carboxyl group-containing urethane resin 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.

[0061] These carboxyl group-containing urethane resins may be used alone or in combination.

[0062] The urethane polymer (B) may be a urethane resin that does not contain a carboxyl group, which is obtained by synthesizing a urethane resin without using the compound (b-4) having a carboxyl group and two or more alcoholic hydroxyl groups. The urethane polymer (B) may also be one obtained using a compound having an isocyanate group directly bonded to an aromatic ring (e.g., tolylene diisocyanate, diphenylmethane diisocyanate, etc.).

[0063] In the synthesis of the urethane polymer (B), when a compound having a reactive group such as a (meth)acryloyl group is used as the compound (c) having one alcoholic hydroxyl group, a urethane prepolymer (B) having a reactive group introduced at its terminal can be easily obtained.

[0064] The urethane polymer (B) may be used alone or in combination of two or more.

[0065] When the urethane polymer (B) contains a carboxyl group, the acid value of the urethane polymer (B) is preferably 10 to 300 (mgKOH / g), more preferably 20 to 200 (mgKOH / g), and particularly preferably 30 to 100 (mgKOH / g). By setting the acid value of the urethane polymer (B) within this range, it becomes easier to obtain a cured product that is excellent in various performances.

[0066] When the urethane polymer (B) contains a carboxyl group, the carboxylic acid equivalent of the urethane polymer (B) is preferably 100 to 2500 (g / eq), more preferably 200 to 2000 (g / eq), and particularly preferably 500 to 1500 (g / eq). By setting the carboxylic acid equivalent of the urethane polymer (B) within this range, it becomes easier to obtain a cured product that is excellent in various performance properties.

[0067] The weight average molecular weight of the urethane polymer (B) is preferably 2,000 to 150,000, more preferably 3,000 to 100,000, and particularly preferably 4,000 to 50,000. By setting the weight average molecular weight of the urethane polymer (B) within this range, it becomes easier to obtain a cured product that is excellent in various performances.

[0068] The content of the urethane polymer (B) in the resin composition is preferably 5 mass% or more, 8 mass% or more, or 10 mass% or more, based on the total mass of the solid content of the resin composition excluding the white pigment, and is preferably 50 mass% or less, 45 mass% or less, or 40 mass% or less.

[0069] Here, the ratio (B / A) of the content of the urethane polymer (B) to the content of the alkali-soluble polymer (A) in the resin composition is preferably 0.1 or more, 0.2 or more, or 0.5 or more, and is preferably 10.0 or less, 5.0 or less, or 4.0 or less.

[0070] The ratio (C / A) of the content of the alkali-soluble polymer (A) to the content of the thiol group-containing compound (C) is preferably 0.10 or more, or 0.20 or more, and is preferably 2.00 or less, 1.50 or less, 1.00 or less, or 0.60 or less.

[0071] The ratio (C / B) of the content of the urethane polymer (B) to the content of the thiol group-containing compound (C) is preferably 0.10 or more, or 0.20 or more, and is preferably 2.00 or less, 1.50 or less, 1.00 or less, or 0.60 or less.

[0072] <<Thiol Group-Containing Compound (C)>> The thiol group-containing compound (C) is a compound having at least one (preferably two or more) thiol groups in one molecule.

[0073] Examples of the thiol group-containing compound (C) include alkylthiol compounds; polyethers having terminal thiol groups; polythioethers having terminal thiol groups; thiol compounds obtained by reacting an epoxy compound with hydrogen sulfide; thiol compounds having terminal thiol groups obtained by reacting a polythiol compound with an epoxy compound; ester compounds of polyols and mercapto organic acids; and mercapto-modified (meth)acrylates.

[0074] Specific examples of the monofunctional thiol group-containing compound (C) include β-mercaptopropionic acid, methyl 3-mercaptopropionate, 2-ethylhexyl 3-mercaptopropionate, n-octyl 3-mercaptopropionate, methoxybutyl 3-mercaptopropionate, stearyl 3-mercaptopropionate, etc. Specific examples of the polyfunctional thiol group-containing compound (C) include 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexaneedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, 1,10-decanedithiol, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptopropionate), tris-[(3-mercaptopropionyloxy)-ethyl] -isocyanurate, tetraethylene glycol bis(3-mercaptopropionate), dipentaerythritol hexakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,4-bis(3-mercaptobutyryloxy)butane, and the like.

[0075] The thiol group-containing compound (C) preferably contains a mercapto-modified (meth)acrylate. The mercapto-modified (meth)acrylate is a compound obtained by reacting a polythiol compound with a polyfunctional (meth)acrylate. Examples of the mercapto-modified (meth)acrylate include those disclosed in JP 2023-097118 A.

[0076] The thiol group-containing compound (C) can be used alone or in combination of two or more.

[0077] The content of the thiol group-containing compound (C) in the resin composition is preferably 2 mass% or more, 5 mass% or more, 10 mass% or more, or 15 mass% or more, based on the total mass of the solid content of the resin composition excluding the white pigment, and is preferably 40 mass% or less, 30 mass% or less, or 20 mass% or less.

[0078] <<White Pigment (D)>> As the white pigment (D), any conventionally known white pigment can be used.

[0079] Examples of the white pigment (D) include inorganic white pigments such as oxides such as titanium oxide, zinc oxide, aluminum oxide, silicon oxide, and magnesium oxide; sulfides such as zinc sulfide; hydroxides such as lead hydroxide and aluminum hydroxide; sulfates such as barium sulfate; and carbonates such as calcium carbonate. The white pigment may also be coated particles whose surfaces are coated with a white material. The white pigment may be surface-treated to increase reflectance, etc.

[0080] The white pigment (D) may be used alone or in combination of two or more.

[0081] The white pigment (D) preferably contains titanium oxide.

[0082] The crystalline form of titanium oxide is not particularly limited, and may be, for example, rutile-type titanium oxide or anatase-type titanium oxide.

[0083] The average particle size of titanium oxide is not particularly limited. The volume average particle size (D50) of titanium oxide is, for example, 100 to 1000 nm, 120 to 500 nm, or 150 to 400 nm.

[0084] When the total of the alkali-soluble polymer (A), the urethane polymer (B), and the thiol group-containing compound (C) is taken as 100 parts by mass, the content of the white pigment (D) (or the content of titanium oxide) is, in terms of solid content, preferably 100 parts by mass or more, 150 parts by mass or more, 200 parts by mass or more, or 250 parts by mass or more, and is preferably 600 parts by mass or less, 550 parts by mass or less, 500 parts by mass or less, 450 parts by mass or less, or 400 parts by mass or less. More specifically, the content of the white pigment (D) (or the content of titanium oxide) is preferably 200 to 500 parts by mass, or 250 to 400 parts by mass.

[0085] <<Thermosetting Resin (E)>> Examples of the thermosetting resin (E) include known thermosetting resins such as epoxy resins, polyfunctional oxetane compounds, episulfide resins having two or more cyclic ether groups and / or cyclic thioether groups in the molecule, polyisocyanate compounds (or blocked isocyanate compounds) having two or more isocyanate groups (or blocked isocyanate groups) in one molecule, amine resins (or derivatives thereof) such as melamine resins and benzoguanamine resins, bismaleimides, oxazines, cyclocarbonate compounds, and carbodiimide resins.

[0086] The thermosetting resin (E) preferably contains an epoxy resin.

[0087] Examples of epoxy resins include bisphenol type epoxy resins (bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol E type epoxy resin, bisphenol M type epoxy resin, bisphenol P type epoxy resin, bisphenol Z type epoxy resin, etc.), novolac type epoxy resins (bisphenol A novolac type epoxy resin, phenol novolac type epoxy resin, cresol novolac epoxy resin, etc.), biphenyl type epoxy resin, biphenyl novolac type epoxy resin, biphenyl aralkyl type epoxy resin, aryl alkylene type epoxy resin, tetraphenylol ethane type epoxy resin, Examples of the epoxy resin include naphthalene-type epoxy resins, anthracene-type epoxy resins, phenoxy-type epoxy resins, dicyclopentadiene-type epoxy resins, norbornene-type epoxy resins, trihydroxyphenylmethane-type epoxy resins, hydantoin-type epoxy resins, tetraphenylolethane-type epoxy resins, brominated epoxy resins, glycidylamine-type epoxy resins, alicyclic epoxy resins, diglycidyl phthalate resins, tetraglycidylxylenoylethane resins, glycidyl methacrylate copolymer epoxy resins, cyclohexylmaleimide and glycidyl methacrylate copolymer epoxy resins, epoxy-modified polybutadiene rubber derivatives, and CTBN-modified epoxy resins.

[0088] The thermosetting resin (E) can be used alone or in combination of two or more.

[0089] The content of the thermosetting resin (E) (or the content of the epoxy resin) in the resin composition is preferably 5 mass% or more, 10 mass% or more, or 15 mass% or more, based on the total mass of the solid content of the resin composition excluding the white pigment, and is preferably 40 mass% or less, 30 mass% or less, or 25 mass% or less.

[0090] <<Polymerization initiator (F)>> Examples of the polymerization initiator (F) include a photopolymerization initiator, a thermal polymerization initiator, etc. The polymerization initiator preferably includes a photopolymerization initiator.

[0091] Examples of the photopolymerization initiator include conventionally known compounds such as halogenated hydrocarbon derivatives (for example, compounds having a triazine skeleton, compounds having an oxadiazole skeleton, and compounds having a trihalomethyl group), acylphosphine compounds such as acylphosphine oxide, hexaarylbiimidazole, oxime compounds such as oxime derivatives, organic peroxides, thio compounds, ketone compounds, aromatic onium salts, ketoxime ethers, aminoacetophenone compounds, hydroxyacetophenone, azo compounds, azide compounds, metallocene compounds, organic boron compounds, and iron arene complexes.

[0092] The polymerization initiator (F) may be used alone or in combination of two or more.

[0093] The content of the polymerization initiator (F) (preferably the content of the photopolymerization initiator) in the resin composition is preferably 5% by mass or more, 10% by mass or more, or 15% by mass or more, based on the total mass of the solid content of the resin composition excluding the white pigment, and is preferably 30% by mass or less, 25% by mass or less, or 20% by mass or less.

[0094] <<Other Components (G)>> Examples of other components include additives such as crosslinking agents, crosslinking aids, antifoaming agents, rust inhibitors, catalysts (epoxy resin reaction catalysts, thermosetting catalysts), antioxidants, leveling agents, inorganic fillers such as silica, sensitizers, adhesion aids, surfactants, plasticizers, flame retardants, cellulose nanofibers, dispersants, and adhesion imparting agents, provided that the effects of the present invention are not impaired.

[0095] The resin composition (G) may further contain an organic solvent as another component. Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone, and cyclohexanone; acetate esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; cellosolves such as cellosolve and butyl cellosolve; carbitols such as carbitol and butyl carbitol; aromatic hydrocarbons such as toluene and xylene; and other organic solvents such as dimethylformamide and dimethylacetamide.

[0096] The other components (G) may each be used alone or in combination of two or more.

[0097] The total content of the other components (G) (excluding the organic solvent) in the resin composition can be 1 mass % or more, 5 mass % or more, or 10 mass % or more, based on the total mass of the solid content excluding the white pigment, and can be 40 mass % or less, 30 mass % or less, or 20 mass % or less.

[0098] In white solder resists, a high amount of white pigment, such as titanium oxide, may be loaded to achieve high reflectivity. In this case, a large amount of white pigment may be present near the surface of the cured product. It has been found that the presence of a large amount of white pigment on the surface of the cured product can scratch objects that come into contact with the cured product (such as clips or metal conveyors) and can easily leave contact marks on the cured product, resulting in defective products. The resistance to the formation of such contact marks is referred to as scratch resistance. According to the resin composition of the present disclosure, by combining an alkali-soluble polymer (A), a urethane polymer (B), and a thiol group-containing compound (C) as components of a resin composition containing a white pigment (D), the cyclohexyl group derived from the alkali-soluble polymer (A) contributes to hydrophobicity and compatibility between the components, and can also provide developability. Furthermore, the use of the urethane polymer (B) can impart flexibility to the resulting cured product. Furthermore, the inclusion of the thiol group-containing compound (C) can rapidly react with other polymerizable components, imparting curability to the surface of the resulting cured product. Furthermore, it has been found that the white pigment (D) is less likely to be located near the surface in cured products obtained using the resin composition according to the present disclosure compared to conventionally known cured products. While the reasons for this are unclear, it is believed that the improved photocurability increases development resistance, making it less likely for titanium oxide to be exposed during development, and that the use of a urethane polymer causes swelling development, which tends to leave a film on the titanium oxide surface. Therefore, it is presumed that a resin composition containing an alkali-soluble polymer (A), a urethane polymer (B), and a thiol group-containing compound (C) can produce a cured product with excellent scratch resistance, low warpage, undercut resistance, etc., even when the resin composition contains the white pigment (D) (especially at a high content). Furthermore, the inclusion of such components in the resin composition according to the present disclosure can suppress discoloration during reflow. Furthermore, it is presumed that the inclusion of a thermosetting resin (E) and a polymerization initiator (F) in the resin composition enhances reactivity and curability, further enhancing the aforementioned effects. When a cured product is formed using the resin composition according to the present disclosure, it can be handled in the same manner as other solder resists, etc.Furthermore, since the cured product is less affected by contact with other articles (clips, metal conveyors, etc.) (there is little effect on how the surface having the cured product is positioned), the cured product can be handled in the same way whether it is provided on one side or both sides. In this way, cured products formed using the resin composition according to the present disclosure are easy to handle and can improve productivity.

[0099] The resin composition according to the present disclosure can be produced, for example, by mixing the raw materials simultaneously or sequentially and appropriately kneading them using a conventionally known means. Alternatively, the raw materials may be prepared as a solution or dispersion before mixing.

[0100] <<<<Uses / Methods of Using Resin Composition>>> Hereinafter, as uses / methods of using the resin composition, a dry film using the resin composition and a cured product obtained using the resin composition will be described.

[0101] <<Dry Film>> The dry film has a resin layer obtained by applying the resin composition of the present disclosure to at least one surface of a first film (substrate film) and then drying the applied resin composition. The dry film is used by laminating the resin layer so that it is in contact with the substrate.

[0102] The dry film can be produced by uniformly applying a resin composition onto a first film using an appropriate method such as a blade coater, lip coater, comma coater, or film coater, followed by drying to form the aforementioned resin layer. The dry film preferably has a second film (protective film) laminated on the resin layer. The first film and the second film may be made of the same film material or different film materials.

[0103] The film materials for the first film and the second film may be any of those known to be used for dry films.

[0104] As the first film, for example, a thermoplastic film such as a polyester film made of polyethylene terephthalate or the like having a thickness of 2 to 150 μm is used.

[0105] The second film may be a polyethylene film, a polypropylene film, or the like, but it is preferable that the adhesive strength with the resin layer is weaker than that of the first film.

[0106] The thickness of the resin layer on the first film is preferably 100 μm or less, more preferably in the range of 5 to 50 μm.

[0107] <<Cured Product>> A cured product can be obtained using the resin composition according to the present disclosure or a dry film having a resin layer obtained from the resin composition according to the present disclosure. A method for producing the cured product and uses thereof will be described below.

[0108] <Method for Producing Cured Product> Hereinafter, as an example of a method for producing a cured product according to the present disclosure, a method will be described in which a resin composition according to the present disclosure is used as a photosensitive resin composition (a resin composition containing a component having a photosensitive moiety) and is applied to a negative photolithography method to produce a patterned film that is a cured product of the resin composition according to the present disclosure.

[0109] First, in step 1, a resin composition is applied to a substrate and dried to form a resin layer. 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 resin composition to the substrate include conventional methods used for applying resin compositions, such as coating with a spin coater, bar coater, blade coater, curtain coater, screen printer, spray coating with a spray coater, and even inkjet methods. 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 incorporation 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.

[0110] The drying method used after applying the resin composition includes air drying, heat drying using an oven or a hot plate, vacuum drying, etc. The 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.

[0111] The substrate on which the resin layer is formed is not particularly limited, and examples include printed wiring boards and flexible printed wiring boards on which circuits have been formed in advance 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 (FR-4, etc.), as well as metal substrates, polyimide films, polyethylene terephthalate films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, wafer plates, etc.

[0112] Next, in step 2, the resin layer formed on the substrate is irradiated (exposed) to light through a patterned photomask or directly in a pattern. When a dry film is used, 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 images directly with a laser based on CAD data from a computer) may also be used. The lamp or laser light source for the direct imaging device may have a maximum wavelength in the range of 350 to 450 nm. The exposure dose varies depending on factors such as film thickness, but is generally 10 to 1,000 mJ / cm. ２ , preferably 20 to 800 mJ / cm ２ The range may be:

[0113] Next, in step 3, the exposed resin layer is treated with a developer. This removes the unexposed portions of the resin layer, forming a patterned cured film. After development, the resin layer may be washed with a rinse liquid, if necessary.

[0114] The development method can be selected from among dipping, showering, spraying, brushing, and the like.

[0115] 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.

[0116] Furthermore, if necessary, in step 4, the patterned cured 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.

[0117] The cured product of the present disclosure can be used for various electronic components, including printed wiring boards. Because the cured product of the present disclosure has excellent reflectance and is less likely to produce defective products, it is preferably used for a light-emitting element mounting substrate.

[0118] Fig. 1 shows an example of a light-emitting element mounting substrate 100 (light-emitting device). More specifically, Fig. 1 shows a conceptual top view of a partial region of the light-emitting element mounting substrate 100. As shown in Fig. 1, the light-emitting element mounting substrate 100 has a substrate 10, a circuit (not shown) provided on the substrate 10, a reflective layer 11 provided so as to cover the circuit, and a plurality of light-emitting elements 12 mounted on the substrate 10.

[0119] The light emitting element 12 is, for example, a light emitting diode.

[0120] The reflective layer 11 is a white solder resist formed from a cured product obtained using the resin composition according to the present disclosure. The reflective layer 11 protects the circuit and efficiently reflects light irradiated from the light emitting element 12 to the front surface (top surface), thereby improving luminous efficiency. Furthermore, the reflective layer 11 has excellent scratch resistance, making it less likely to scratch articles that come into contact with the light emitting element mounting substrate 100. Furthermore, the reflective layer 11, which is a cured product obtained using the resin composition according to the present disclosure, has excellent properties such as low warpage and undercut resistance, thereby improving the reliability of the light emitting element mounting substrate 100.

[0121] 1, the light-emitting element mounting substrate 100 has a plate-like structure, but the light-emitting element mounting substrate 100 may have a structure in which at least a part or all of it is curved or bent, or may be a flexible wiring substrate. In addition, the arrangement of the light-emitting elements 12, such as the density of the light-emitting elements 12 and the distance between the light-emitting elements 12, can be freely changed as appropriate.

[0122] <<<Preparation of Resin Compositions>>> Resin compositions according to Examples 1-4 and Comparative Examples 1-5 were prepared using the raw materials shown below in the amounts shown in Table 1. Table 1 shows the content (parts by mass) of each raw material converted into solid content.

[0123] <<Alkali-soluble polymer (A) containing a cyclohexyl group and a carboxyl group>> <A1> An alkali-soluble polymer (A1) containing a cyclohexyl group and a carboxyl group was produced under the following conditions.

[0124] A four-neck flask equipped with a reflux condenser, a thermometer, a glass tube for nitrogen replacement, and a stirrer was charged with 223.8 parts by mass (2.6 mol) of methacrylic acid, 100.1 g (1.0 mol) of methyl methacrylate, 246.7 parts by mass (1.6 mol) of cyclohexyl acrylate, 1,400 parts by mass of dipropylene glycol monomethyl ether, and 16.4 parts by mass (0.1 mol) of azobisisobutyronitrile, and the mixture was heated at 75°C for 5 hours under a nitrogen stream to allow the polymerization reaction to proceed. After adding 17.0 parts by mass (0.07 mol) of triphenylphosphine, 156.4 parts by mass (1.1 mol) of glycidyl methyl methacrylate was added, and the mixture was heated at 90 to 100°C for 6 hours to carry out the addition of acryloyl groups. Thereafter, the triphenylphosphine was deactivated by air bubbling to obtain an alkali-soluble polymer (A1) containing a cyclohexyl group and a carboxyl group (solid acid value: 110 mg KOH / g, solid concentration: 35 mass%, weight-average molecular weight Mw: 15,000, acrylic equivalent: about 800, cyclohexyl group equivalent: about 500).

[0125] <<Urethane Polymer (B)>> <B1> Urethane polymer (B1) was produced under the following conditions. 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 22.1 g (0.16 mol) of hydroxyphenylethyl alcohol as a compound having one alcoholic hydroxyl group and one or more phenolic hydroxyl groups per molecule were charged into a reaction vessel equipped with a stirrer, thermometer, and condenser. Next, 200.9 g (1.08 mol) of trimethylhexamethylene diisocyanate as a compound having an isocyanate group not directly bonded to an aromatic ring was charged, and the mixture was heated with stirring. Heating was stopped when the temperature reached 60°C. When the temperature in the reaction vessel began to decrease, heating was resumed and stirring was continued at 80°C. Infrared absorption spectrum of isocyanate group (2280 cm －１The reaction was terminated after confirming that the carboxyl group-containing urethane polymer (B1) had a solid acid value of 48.8 mg KOH / g, a carboxylic acid equivalent of 1,200, and a weight-average molecular weight (Mw) of 16,000.

[0126] <B2> Urethane polymer Product name: ART RESIN UN-3320HA (manufactured by Negami Chemical Industrial Co., Ltd.)

[0127] <<Thiol Group-Containing Compound (C)>> <C1> Thiol group-containing mercapto-modified acrylate Product name: ADDITOL LED 01 (manufactured by Daicel Corporation) <C2> Secondary multifunctional thiol compound Product name: Karenz MT PE1 (manufactured by Resonac Corporation)

[0128] <<White Pigment (D)>> <D1> Titanium oxide Product name: TIPAKE PFC107 (manufactured by Ishihara Sangyo Kaisha, Ltd., average particle size D50 = 250 nm)

[0129] <<Thermosetting resin (E)>> <E1> Biphenyl novolac epoxy resin Product name: NC-3000H-CA75 (manufactured by Nippon Kayaku Co., Ltd.) <E2> Biphenyl-based bifunctional epoxy resin Product name: YX-4000 (manufactured by Mitsubishi Chemical Corporation, crushed grade)

[0130] <<Polymerization initiator (F)>> <F1> Acylphosphine photopolymerization initiator Product name: Omnirad TPO H (manufactured by IGM Resins B.V.) <F2> Oxime photopolymerization initiator Product name: Irgacure OXE04 (manufactured by BASF Japan)

[0131] <<Other Components (G)>> <G1> Crosslinking agent EO9 Bis A Methacrylate Product name: BPE-900 (manufactured by Shin-Nakamura Chemical Co., Ltd.)

[0132] <<<Evaluation>>> The resin compositions according to each Example and Comparative Example were evaluated for reflectance, scratch resistance, low warpage, undercut resistance, and reflow discoloration resistance according to the following evaluation methods. The evaluation results are shown in Table 1.

[0133] <<Substrate Preparation Conditions>> Substrates were prepared under the following conditions. A copper-clad laminate (ESPANEX (manufactured by Nippon Steel Chemical & Material Co., Ltd.; double-sided product with a copper thickness of 12 μm and a polyimide thickness of 25 μm)) having a thickness of 50 μm and a size of 150 mm and 100 mm was washed with sulfuric acid and hydrogen peroxide, and each of the resin compositions of Examples 1-4 and Comparative Examples 1-5 was applied to a film thickness of 20 μm using a 100-mesh screen, and dried at 70°C for 30 minutes in a hot air circulation drying oven. Thereafter, an exposure device equipped with a high-pressure mercury lamp (short arc lamp) was used to apply an integrated exposure dose of 500 mJ / cm. ２ Thereafter, the coating was heated in a hot air circulation drying oven at 150° C. for 60 minutes for full curing, to obtain a test substrate.

[0134] <<Reflectance>> For the test substrates obtained by the above method, the cured surface was measured using a spectrophotometer (CM-2600d, manufactured by Konica Minolta) using the SCI method (including regular reflection) to determine the Y value (%) of the XYZ color system at 450 nm, and this was taken as the reflectance. (Evaluation criteria) A (Excellent): Reflectance of 87% or more B (Good): Reflectance of 84% or more but less than 87% C (Fail): Reflectance of less than 84%

[0135] <<Scratch Resistance>> The likelihood of producing defective products was evaluated by scratch resistance. A substrate (double-sided copper-clad flexible board) consisting of an 18 μm thick, 100 mm x 100 mm polyimide film with 35 μm copper foil attached to both sides was placed on top of the obtained test substrate, and a 12 mm diameter, circular, flat-bottomed, 1 kg weight (weight) was placed on top of that. In this state, the double-sided copper-clad flexible board was pulled parallel for approximately 10 cm in 10 seconds, and the presence of black marks on the coating was evaluated according to the following criteria: (Evaluation Criteria) A (Excellent): No contact marks (black streaks) were observed after five or more tests. B (Good): Contact marks (black streaks) were observed after two to four tests. C (Unacceptable): Contact marks (black streaks) were observed after one test.

[0136] <<Low Warpage>> The obtained test substrate was cut into a piece of 50 mm x 50 mm, and placed on a cutting mat at room temperature to measure the total warpage at the four corners. The test was performed five times, and the average value was calculated and evaluated according to the following criteria. (Evaluation criteria) A (Excellent): Warpage is less than 1 mm. B (Good): Warpage is 1 mm or more but less than 4 mm. C (Unacceptable): Warpage is 4 mm or more.

[0137] <<Undercut Properties>> A copper-clad laminate (ESPANEX (manufactured by Nippon Steel Chemical & Material Co., Ltd.; copper thickness: 12 μm, polyimide thickness: 25 μm, double-sided) having a thickness of 50 μm × 150 mm × 100 mm and having conductor circuits with L / S = 20 μm / 20 μm to 100 μm / 100 μm formed at intervals of L / S = 10 μm / 10 μm) was washed with sulfuric acid and hydrogen peroxide, and each of the resin compositions of Examples 1-4 and Comparative Examples 1-5 was applied using a 100-mesh screen to a film thickness of 20 μm, and then dried in a hot-air circulating drying oven at 70°C for 30 minutes. Thereafter, an exposure device equipped with a high-pressure mercury lamp (short arc lamp) was used to form a pattern with L / S = 20 μm / 20 μm to 100 μm / 100 μm in increments of L / S = 10 μm / 10 μm, with an integrated exposure dose of 500 mJ / cm ２ The film was then exposed to light. It was then heated in a hot air circulation drying oven at 150°C for 60 minutes for full curing, yielding a substrate for undercut properties evaluation. The line width of the obtained substrate for undercut properties evaluation was measured at a measurement magnification of 500 times using an optical microscope (DIGITAL MICROSCOPE VHX-6000, manufactured by Keyence Corporation), and evaluated according to the following evaluation criteria. (Evaluation criteria) A (Excellent): A 50 μm line remains on the undercut properties test substrate. B (Good): No 50 μm line remains on the undercut properties test substrate, but a 60 μm line remains. C (Unacceptable): No 60 μm line remains on the undercut properties test substrate.

[0138] <<Reflow Discoloration>> The obtained test substrates were subjected to 1 to 5 reflow processes using a reflow machine (NIS-20-82S manufactured by Atec Techtron Co., Ltd.) in an air atmosphere at a peak temperature of 260°C for 60 seconds, and then visually evaluated for discoloration. (Evaluation criteria) A (Excellent): No discoloration after 5 reflows. B (Good): No discoloration after 3 reflows, but discoloration after 4 reflows. C (Unacceptable): Discoloration after 1 to 3 reflows.

[0139]

[0140] The resin composition according to the present disclosure can produce a white solder resist that has high reflectance and is less likely to produce defective products, and is therefore preferably used for producing various electronic components, including printed wiring boards (particularly light-emitting element mounting substrates). CROSS-REFERENCE TO RELATED APPLICATIONS

[0141] This application claims priority based on Japanese Patent Application No. 2023-187237, 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 resin composition comprising: (A) an alkali-soluble polymer containing a cyclohexyl group and a carboxyl group; (B) a urethane polymer; (C) a compound containing a thiol group; and (D) a white pigment.

2. The resin composition according to claim 1, wherein the white pigment (D) contains titanium oxide.

3. The resin composition according to claim 1, wherein the urethane polymer (B) contains a carboxyl group.

4. A resin composition according to claim 1 or 2, wherein the content of the white pigment (D) is 200 to 500 parts by mass, calculated as solid content, relative to 100 parts by mass of the total of the alkali-soluble polymer (A), the urethane polymer (B), and the compound (C).

5. The resin composition according to claim 1 or 2, which further comprises a polymerization initiator.

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

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

8. A light emitting element mounting substrate having the cured product according to claim 7.

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