Inkjet marking ink composition for flexible substrate

Abstract

One embodiment of the present invention relates to a resin composition comprising (A) a monofunctional (meth)acrylate, (B) a polyfunctional (meth)acrylate, (C) a thermosetting resin, (D) a photopolymerization initiator, and (E) an inorganic filler, wherein the acrylic equivalent is 160 g / eq or more and 280 g / eq or less. This resin composition of the present invention can provide an inkjet marking ink composition that, when used on flexible substrates, exhibits excellent flexibility and adhesion, and can suppress peeling and cracking during folding or bending. Furthermore, it can provide an inkjet marking ink composition with excellent storage stability and high adhesion.

Description

[Technical Field]

[0001] This invention relates to an inkjet marking ink composition for flexible substrates. [Previous Technology]

[0002] Marking ink is used in the subsequent process of solder resist coating process in the manufacturing of printed circuit boards (PCBs) before electronic components are assembled on the printed circuit board (PCB) to mark the characters displayed when the circuit board is installed.

[0003] With the increasing use of inkjet printing, in addition to rigid substrates, rigid-flexible substrates and flexible substrates are also being widely used as substrates for coating inkjet components. Even so, previous inventions of inkjet components have focused primarily on the physical properties of rigid substrates, such as the adhesion, scratch resistance, pencil hardness, and reactivity of the components, without considering the flexibility and bendability required for flexible substrates.

[0004] When this prior inkjet composition is used on a flexible substrate, peeling and cracking may occur when folded or bent. In addition, there is also the issue of adhesion to the flexible substrate (e.g., polyimide substrate).

[0005] On the other hand, in the case of resin compositions, there is a tendency that the higher the degree of crosslinking, the higher the storage stability (e.g., solvent resistance), but the higher the degree of crosslinking, the lower the adhesion to the substrate. That is, it was previously thought that it was difficult to balance storage stability and adhesion, and a resin composition that can produce a cured material with excellent storage stability and adhesion high enough to be used on flexible substrates is needed.

[0006] [Patent Documents] (Patent Document 1) Japanese Patent Publication No. 2019-522689 (Patent Document 2) Korean Patent Publication No. 2013-0082159 [Summary of the Invention]

[0007] [The problem the invention aims to solve]

[0008] The present invention addresses the problems described above by providing an inkjet marking ink composition that, when used on a flexible substrate, exhibits excellent flexibility and adhesion, and can suppress peeling and cracking during folding or bending. Furthermore, the present invention provides an inkjet marking ink composition with excellent storage stability and high adhesion.

[0009] [Technical means to solve the problem]

[0010] One embodiment of the present invention relates to a resin composition.

[0011] In one state sample, the above resin composition includes (A) monofunctional (meth)acrylate, (B) polyfunctional (meth)acrylate, (C) thermosetting resin, (D) photopolymerization initiator and (E) inorganic filler, wherein the acrylic equivalent can be more than 160 g / eq and less than 280 g / eq.

[0012] In one state sample, the above-mentioned (A) monofunctional (meth)acrylate and (B) polyfunctional (meth)acrylate may include polar functional groups that can form crosslinking bonds.

[0013] In one state sample, the above-mentioned polar functional group may be selected from one or more of the group consisting of hydroxyl, carboxyl, amino group, amine group, carbonyl, acrylic, acrylonitrile, nitrile, vinyl, halogen, carbamate and ester groups.

[0014] In one state sample, the above (A) monofunctional (meth)acrylate may include (meth)acrylate having hydroxyl groups.

[0015] In one state sample, the above (A) monofunctional (meth)acrylate or (B) polyfunctional (meth)acrylate may have an epoxide skeleton.

[0016] In a single sample, based on the total weight of the resin composition, the content of (A) monofunctional (meth)acrylate may be 30 to 80% by weight.

[0017] In a single sample, based on the total weight of the resin composition, the content of (B) polyfunctional (meth)acrylate may be 2 to 45% by weight.

[0018] In one state sample, the above (A) monofunctional (meth)acrylate may include (meth)acrylate having hydroxyl groups, and the content of the above (meth)acrylate having hydroxyl groups may be 2 to 50 by weight based on the total weight of the resin composition.

[0019] In one state sample, the above (C) thermosetting resin may include end-capped isocyanate.

[0020] In one state sample, the above (A) monofunctional (meth)acrylate includes (meth)acrylate having hydroxyl groups, and the above (C) thermosetting resin includes end-capped isocyanate, wherein the equivalent ratio of isocyanate to hydroxyl group may be 1:4 to 1:15.

[0021] In a single sample, based on the total weight of the resin composition, the content of (C) thermosetting resin may be 2 to 15% by weight.

[0022] In one state sample, the above (D) photopolymerization initiator may be selected from one or more of the group consisting of phosphine oxides, 9-oxosulfur compounds and benzoic acid esters.

[0023] In a sample, the inorganic filler (E) mentioned above may be selected from one or more of the group consisting of titanium oxide, zinc oxide, carbon black, basic carbonate, basic sulfate, sulfate, zinc sulfide, antimony oxide, aluminum hydroxide, silicon oxide and barium sulfate.

[0024] In another embodiment, the resin composition may include (A) a monofunctional (meth)acrylate, (B) a polyfunctional (meth)acrylate, (C) a thermosetting resin, (D) a photopolymerization initiator and (E) an inorganic filler, wherein the (A) monofunctional (meth)acrylate may include a (meth)acrylate having hydroxyl groups, and the (C) thermosetting resin may include a capped isocyanate, wherein the equivalent ratio of isocyanate to hydroxyl groups may be 1:4 to 1:15.

[0025] In one state sample, the above-mentioned resin composition may be as follows: used to form a mark in a subsequent process of the process of coating photosensitive solder resist (PSR) on a printed circuit board.

[0026] Another embodiment of the present invention relates to a printed circuit board having a hardened material formed of the above-mentioned resin composition on a substrate.

[0027] [Effects of the Invention]

[0028] The resin composition of one embodiment of the present invention has an acrylic equivalent adjusted to a specific range, resulting in a suitable number of crosslinking points compared to previous marking inks, and the distance between the crosslinking points is relatively large, thus exhibiting high flexibility and high adhesion. When the above-mentioned resin composition is used as an inkjet marking ink composition in a flexible substrate, it exhibits excellent flexibility due to these characteristics and can suppress peeling and cracking when folded or bent.

Implementation Method

[0030] Hereinafter, various embodiments of the present invention will be described.

[0031] [Resin Composition]

[0032] One embodiment of the present invention relates to a resin composition comprising (A) a monofunctional (meth)acrylate, (B) a polyfunctional (meth)acrylate, (C) a thermosetting resin, (D) a photopolymerization initiator and (E) an inorganic filler.

[0033] In one sample, the acrylic equivalent of the above-mentioned resin composition can be 160 g / eq or more and 280 g / eq or less. The acrylic equivalent of the resin composition is obtained by dividing the mass (g) of the resin composition by the number of moles of (meth)acrylic acid groups in the resin composition per mole of (meth)acrylic acid groups. If the acrylic equivalent of the resin composition is less than 160 g / eq, there are more crosslinking points between the acrylate monomers in the resin composition and the distance between the crosslinking points is shorter, resulting in higher strength and insufficient flexibility, making it unsuitable for use in flexible substrates. If the acrylic equivalent of the resin composition exceeds 280 g / eq, there is a problem of decreased crosslinking density during photocuring and decreased pencil hardness. The present invention adjusts the acrylic equivalent in the resin composition to a specific range to have an appropriate number of crosslinking points and can sufficiently increase the distance between the crosslinking points, thus providing flexibility suitable for use in flexible substrates and appropriate hardness.

[0034] For example, the above-mentioned resin composition may be used in a subsequent process of applying solder resist to a printed circuit board, thereby marking the characters displayed when the circuit board is mounted.

[0035] Hereinafter, each component of the resin composition will be described in detail.

[0036] [(Meth)acrylate]

[0037] In this specification, the term "(meth)acrylate" is a systematic term for acrylates, methacrylates and mixtures thereof, and the same applies to other similar expressions. Monofunctional (meth)acrylate refers to a (meth)acrylate having one (meth)acrylic group, and polyfunctional (meth)acrylate refers to a (meth)acrylate having two or more (meth)acrylic groups.

[0038] For example, the monofunctional (meth)acrylate may be selected from ethyl (meth)acrylate, trifluoroethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, glycidyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tributyl (meth)acrylate, isoamyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecanyl (meth)acrylate, isobornyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, phenoxy (meth)acrylate. Esters of monovalent alcohols and (meth)acrylates, including ethyl methacrylate, benzyl methacrylate, tetrahydrofurfuryl methacrylate, ethoxydiethylene glycol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, butoxydiethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, 2-ethylhexyldiethylene glycol (meth)acrylate, 4-tert-butylcyclohexyl methacrylate, phenol (EO) acrylate, and 3-phenoxybenzyl (meth)acrylate.2-Hydroxyethyl (meth)acrylate, 2-Hydroxypropyl (meth)acrylate, 2-Hydroxybutyl (meth)acrylate, 4-Hydroxybutyl (meth)acrylate, 2-Hydroxy-3-phenoxypropyl (meth)acrylate, Octyl acrylate, Nonyl acrylate, Isononyl acrylate, 3,3,5-Trimethylcyclohexyl acrylate, Cyclic Trimethylolpropane Formaldehyde acrylate, 1-Naphthyl (meth)acrylate, 1-Ethylcyclohexyl (meth)acrylate, 1-Methylcyclohexyl (meth)acrylate, 1-Ethylcyclopentyl (meth)acrylate, 1-Methylcyclopentyl (meth)acrylate, Dicyclopentenyl (meth)acrylate, Dicyclopentenyl (meth)acrylate Pentenyloxyethyl ester, dicyclopentyl (meth)acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, tetrahydrodicyclopentadienyl (meth)acrylate, 2-(o-phenylphenoxy)ethyl (meth)acrylate, isobornylcyclohexyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolane-4-yl)meth(meth)acrylate, 1-adamantyl (meth)acrylate, 3-hydroxy-1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, 2-isopropyladamantyl-2-yl (meth)acrylate, (Adamantane-1-oxy)meth(meth)acrylate, 2-isopropyl-2-adamantyl(meth)acrylate, 1-methyl-1-ethyl-1-adamantylmethanol(meth)acrylate, 1,1-diethyl-1-adamantylmethanol(meth)acrylate, 2-cyclohexylpropane-2-yl(meth)acrylate, 1-isopropylcyclohexyl(meth)acrylate, 1-ethylcyclopentyl(meth)acrylate, tetrahydropiperanyl(meth)acrylate The monofunctional (meth)acrylate is one or more of the following groups: esters, tetrahydro-2-furanyl (meth)acrylate, 2-oxotetrahydrofuran-3-yl (meth)acrylate, (5-oxotetrahydrofuran-2-yl)meth(meth)acrylate, (2-oxo-1,3-dioxolane-4-yl)meth(meth)acrylate, 1-ethoxyethyl (meth)acrylate, and mono(2-acryloxyethyl) succinate, but is not limited thereto. The monofunctional (meth)acrylate can be a single compound or a mixture of two or more different compounds.

[0039] For example, the polyfunctional (meth)acrylate may be selected from ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and polypropylene glycol di(meth)acrylate. Neopentyl glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, neopentyl glycol adipic acid di(meth)acrylate, neopentyl glycol hydroxypentanoic acid di(meth)acrylate, dicyclopentyl di(meth)acrylate, dihydroxymethyltricyclodecanoic acid di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified di(meth)acrylate, isocyanurate di(meth)acrylate, allylated cyclohexyl di(meth)acrylate, EO-modified di(meth)acrylate... Difunctional (meth)acrylates such as methacrylates, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tri(acryloyloxyethyl)isocyanurate, isocyanuric acid EO-modified tri(meth)acrylate, etc., trifunctional (meth)acrylates, pentaerythritol tetra(meth)acrylate The polyfunctional methacrylate comprises one or more of the following groups: esters, tetra(meth)acrylates (such as dimethylolpropane tetra(meth)acrylate), pentaerythritol penta(meth)acrylate, propionic acid-modified pentaerythritol penta(meth)acrylate, pentaerythritol hexa(meth)acrylate, caprolactone-modified pentaerythritol hexa(meth)acrylate, pentaerythritol penta(meth)acrylate, propionic acid-modified pentaerythritol penta(meth)acrylate, and pentaerythritol hexa(meth)acrylate, but is not limited to these. A polyfunctional methacrylate may be a single compound or a mixture of two or more different compounds.

[0040] In one embodiment of the present invention, the resin composition includes (A) monofunctional (meth)acrylate and (B) polyfunctional (meth)acrylate to achieve a viscosity and hardness suitable for inkjet printing.

[0041] In one state sample, the above-mentioned (A) monofunctional (meth)acrylate and (B) polyfunctional (meth)acrylate may include polar functional groups capable of forming crosslinking bonds. The polar functional group may be selected from one or more of the group consisting of hydroxyl, carboxyl, amino group, amine group, carbonyl, acrylate, acrylonitrile, nitrile, vinyl, halogen, carbamate and ester groups, but is not limited thereto.

[0042] For example, the monofunctional (meth)acrylate described above (A) may include (meth)acrylates having hydroxyl groups. Based on the total weight of the resin composition, the content of the aforementioned (meth)acrylates having hydroxyl groups may be 2 to 50% by weight, 5 to 50% by weight, 2 to 45% by weight, or 10 to 40% by weight. If the above range is not reached, the hardness will weaken due to decreased adhesion to the substrate or decreased crosslinking density; if the above range is exceeded, cracking during folding or bending will increase and the hardness will weaken.

[0043] For example, the above-mentioned (A) monofunctional (meth)acrylate or (B) polyfunctional (meth)acrylate may have an epoxy alkane backbone, and the flexibility of the (meth)acrylate may be improved by including an epoxy alkane backbone. For example, the above-mentioned (A) monofunctional (meth)acrylate or (B) polyfunctional (meth)acrylate may have an epoxy methane or epoxy ethylene backbone.

[0044] For example, the above-mentioned (A) monofunctional (meth)acrylate may include one or more of the group consisting of cyclic trimethylolpropane formal acrylate (CFTA) and isobornyl acrylate (IBXA) to improve softness.

[0045] For example, the above-mentioned (B) multifunctional (meth)acrylate may include one or more of the group consisting of pentaerythritol tetraacrylate (PETRA) and ethylene oxide modified trimethylolpropane triacrylate ((EO)nTrimethylolpropane Triacrylate ((EO)nTMPTA (n is 1 to 6)) to improve hardness and solvent resistance.

[0046] In one embodiment of the present invention, based on the total weight of the resin composition, the content of (A) monofunctional (meth)acrylate can be 30 to 80% by weight, 40 to 75% by weight, or 50 to 70% by weight. The above composition may include solid components and solvents. When the content of (A) monofunctional (meth)acrylate is 70% by weight or less based on the total weight of the resin composition, excellent hardness characteristics can be achieved.

[0047] In one embodiment of the present invention, based on the total weight of the resin composition, the content of (B) polyfunctional (meth)acrylate can be 2 to 50% by weight, 5 to 50% by weight, 2 to 45% by weight, 5 to 45% by weight, 6 to 33% by weight, or 8 to 21% by weight. The above composition may include solid components and solvents. If the content of (B) polyfunctional (meth)acrylate is 21% by weight or less based on the total weight of the resin composition, excellent flexural strength can be achieved. The content of (A) monofunctional (meth)acrylate and (B) polyfunctional (meth)acrylate can be adjusted to the above range to adjust the acrylic equivalent in the resin composition to a specific range.

[0048] For example, the above-mentioned (A) monofunctional (meth)acrylate includes (meth)acrylate having hydroxyl groups, and the content of the above-mentioned (meth)acrylate having hydroxyl groups may be 5 to 50% by weight or 6 to 45% by weight, based on the total weight of the resin composition.

[0049] [(C) Thermosetting resin]

[0050] Known thermosetting resins can be used. In this invention, the resin composition includes a thermosetting resin, thereby improving the heat resistance of the cured coating. Examples of known and commonly used thermosetting resins include epoxy resins, isocyanate compounds, terminated isocyanate compounds, amino resins, polyfunctional oxobutane compounds, benzo[a] resins, carbodiimide resins, cyclic carbonate compounds, and cyclic sulfur resins. One thermosetting resin can be used alone or in combination of two or more.

[0051] For example, (C) the thermosetting resin may be a capped isocyanate. As a capped isocyanate, the addition reaction product of an isocyanate and an isocyanate capping agent is used. The capped isocyanate may be selected from at least one of difunctional or trifunctional. Difunctional or trifunctional means having two or three isocyanates protected by a capping agent.

[0052] Examples of isocyanates that can react with isocyanate end-capping agents include isocyanurate type, biuret type, and adduct type.

[0053] Specific examples of isocyanates include aromatic polyisocyanates such as 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, naphthalene-1,5-diisocyanate, o-xylene isocyanate, m-xylene isocyanate and 2,4-toluene dimer; aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4-methylene bis(cyclohexyl isocyanate) and isophorone diisocyanate; and alicyclic polyisocyanates such as bicycloheptane triisocyanate.

[0054] Examples of isocyanate capping agents used in capped isocyanates include phenolic capping agents such as phenol, cresol, xylenol, chlorophenol, and ethylphenol; lactamine capping agents such as ε-caprolactam, δ-pentanolactamamine, γ-butanolactamamine, and β-propiolactamamine; active methylene capping agents such as ethyl acetoacetone and acetoacetone; alcohol capping agents such as methanol, ethanol, propanol, butanol, pentanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, benzyl ether, methyl glycolate, butyl glycolate, diacetone alcohol, methyl lactate, and ethyl lactate; and formaldehyde oxime, acetaldehyde oxime, etc. Oxime end-capping agents such as acetone oxime, methyl ethyl ketone oxime, diacetyl oxime, and cyclohexane oxime; thiol end-capping agents such as butanethiol, hexanethiol, tributanethiol, thiophene, methyl thiophene, and ethyl thiophene; acid-amine end-capping agents such as acetylamine and benzoxylamine; acetylimine end-capping agents such as succinic acid acetylimine and maleic acid acetylimine; amine end-capping agents such as xyleneamine, aniline, butylamine, and dibutylamine; imidazole end-capping agents such as imidazole and 2-ethylimidazole; imine end-capping agents such as methylimine and propylimine; pyrazole end-capping agents such as dimethylpyrazole; maleic acid ester end-capping agents such as diethyl maleic acid; and active ester end-capping agents such as phenol esters, thiophene esters, N-hydroxylamine esters, and heterocyclic hydroxyl compounds.

[0055] As end-capped isocyanates, commercially available examples include, for instance, Desmodule (registered trademark) BL-3175, BL-4265, BL-1100 / 1, BL-1265 / 1, TPLS-2957, TPLS-2062, TPLS-2078, TPLS-2117, Desmosam 2170, Desmosam 2265 (all manufactured by Sumitomo Bayer Urethane Ltd.), Coronate (registered trademark) 2512, Coronate 2513, Coronate 2520 (all manufactured by Doso Ltd.), B-830, B-815, B-846, B-870, B-874, B-882 (all manufactured by Mitsui Kagaku Polyurethane Ltd.), Duranate SBN-70D, TPA-B80E, 17B-60P, E402-B80B, MF-K60B, SBB-70P, SBB-70D, MF-B60B (all manufactured by Asahi Kasei Co., Ltd.), TRIXENE BI 7982, Don 7950, Don 7951, Don 7960, Don 7961 (manufactured by Baxenden Chemicals Limited). Additionally, Desmodule BL-3175 and BL-4265 are obtained using methyl ethyl oxime as a capping agent. One of these can be used alone, or in combination of two or more.

[0056] For example, in the resin composition of the present invention, (A) the monofunctional (meth)acrylate includes (meth)acrylate having hydroxyl groups, and (C) the thermosetting resin includes end-capped isocyanate, wherein the isocyanate to hydroxyl equivalent ratio can be from 1:4 to 1:15. The hydroxyl equivalent of the resin composition is obtained by dividing the mass (g) of the resin composition by the number of moles of hydroxyl groups in the resin composition, based on the mass of the resin composition per mole of isocyanate. The isocyanate equivalent of the resin composition is obtained by dividing the mass (g) of the resin composition by the number of moles of isocyanate in the resin composition, based on the mass of the resin composition per mole of isocyanate. When the hydroxyl to isocyanate equivalent ratio is in the range of 4 to 15 relative to the isocyanate equivalent of 1, good adhesion, flexibility, and sufficient film strength can be obtained. If the hydroxyl equivalent is less than 4, the hydroxyl groups will be smaller, resulting in decreased adhesion and poor storage stability. On the other hand, if the hydroxyl equivalent exceeds 15, the crosslinking density will decrease and become difficult to reflect the coating strength.

[0057] In the resin composition of the present invention, the content of (C) thermosetting resin is based on the total weight of the resin composition and may be 2 to 15% by weight, 3 to 13% by weight, or 4 to 12% by weight. The above composition may include solid components and solvents.

[0058] If the content of thermosetting resin (C) is within the above range, it has the effect of obtaining appropriate adhesion and hardness.

[0059] In the resin composition of the present invention, the content of the capped isocyanate is based on the total weight of the resin composition and may be 2 to 15% by weight, 3 to 13% by weight, or 4 to 12% by weight. The above composition may include solid components and solvents.

[0060] [(D) Photopolymerization initiator]

[0061] There are no particular restrictions on the photopolymerization initiator, as long as it can polymerize (meth)acrylates by irradiation with an energy line; free radical polymerization initiators can be used. For example, there are no particular restrictions on the photopolymerization initiator, as long as it absorbs light in the range of 350 nm to 450 nm. A single photopolymerization initiator can be used alone, or two or more can be used in combination.

[0062] As a photopolymerization initiator, specifically, examples include bis-(2,6-dichlorobenzoxyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoxyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoxyl)-4-propylphenylphosphine oxide, bis-(2,6-dichlorobenzoxyl)-1-naphthylphosphine oxide, bis-(2,6-dimethoxybenzoxyl)phenylphosphine oxide, bis-(2,6-dimethoxybenzoxyl)-2,4,4-trimethylpentylphosphine oxide, bis-(2,6-dimethoxybenzoxyl)-2,5-dimethylphenylphosphine oxide, bis-(2,4,6-trimethylbenzoxyl)-phenylphosphine oxide, and other bis(2,6-dimethoxybenzoxyl)phenylphosphine oxides; 2,6-dimethoxybenzoxyldiphenylphosphine oxide... Phosphorus oxides, including mono-phosphorus oxides such as 2,6-dichlorobenzoxyphosphine oxide, 2,4,6-trimethylbenzoxyphosphine methyl ester, 2-methylbenzoxyphosphine oxide, isopropyl terpenoid phenylphosphine acid, 2,4,6-trimethylbenzoxyphosphine oxide, and ethylphenyl(2,4,6-trimethylbenzoxyphosphine)phosphonate; hydroxyacetophenones such as 1-hydroxy-cyclohexylphenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propane-1-one)-benzyl]phenyl}-2-methyl-propane-1-one, and 2-hydroxy-2-methyl-1-phenylpropane-1-one; benzoin, diphenyl... Benzoin derivatives include ethylene glycol, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, and benzoin n-butyl ether; benzoin alkyl ethers; benzophenone derivatives include p-methylbenzophenone, milchnerone, methylbenzophenone, 4,4'-dichlorobenzophenone, and 4,4'-bis(diethylamino)benzophenone; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-linyl-1-propanone, and 2-benzyl-2-dimethylamino-1-(4-linylphenyl)-butanone-1,2-(dimethylamino)-2-[(4- Acetophenones such as [methylphenyl]-1-[4-(4-linyl)phenyl]-1-butanone and N,N-dimethylaminoacetophenone; 9-oxosulfur derivatives such as 9-oxosulfur, 2-ethyl9-oxosulfur, 2-isopropyl9-oxosulfur, 2,4-dimethyl9-oxosulfur, 2,4-diethyl9-oxosulfur, 2-chloro9-oxosulfur, and 2,4-diisopropyl9-oxosulfur; anthraquinones such as anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tributylanthraquinone, 1-chloroanthraquinone, 2-pentylanthraquinone, and 2-aminoanthraquinone; ketols such as acetophenone dimethyl ketol and benzyl dimethyl ketol; and benzoate derivatives such as ethyl-4-dimethylaminobenzoate, ethyl 2-(dimethylamino)benzoate, and ethyl p-dimethylbenzoate.Oxime esters such as 1,2-octanedione, 1-[4-(phenylthio)phenyl]-2-(O-benzoxime), ethanol, 1-[9-ethyl-6-(2-methylbenzoxime)-9H-carbazole-3-yl]-, and 1-(O-acetyloxime); bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrole-1-yl) Titanium cadmium derivatives include bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyrrolo-1-yl)ethyl)phenyl]titanium, bis(2,6-difluoro-3-(1-hydropyrrolo-1-yl)phenyl)dicenoctanium, etc.; phenyl disulfide 2-nitrofuran, butylin, anisolein ethyl ether, azobisisobutyronitrile, tetramethylthiuram disulfide, etc.

[0063] Commercially available α-aminoacetophenone photopolymerization initiators include Omnirad 907, 369, 369E, 379, and Esacure ONE manufactured by IGM Resins. Commercially available phosphine oxide photopolymerization initiators include Omnirad TPO, TPO-L, and 819 manufactured by IGM Resins, and Mosaphoto 348 manufactured by UFC Corporation. Commercially available oxime ester photopolymerization initiators include Irgacure OXE01 and OXE02 manufactured by BASF Japan, N-1919, Adeka Arkles NCI-831, and NCI-831E manufactured by ADEKA Ltd., and TR-PBG-304 manufactured by Changzhou Tronly New Electronic Materials Co., Ltd. Commercially available 9-oxosulfur photopolymerization initiators include ITX from Zhejiang Shou & Fu Chemtrade Co., Ltd. Commercially available titanoceramic photopolymerization initiators include Mosaphoto 533 manufactured by UFC Corporation.

[0064] For example, the above-mentioned (D) photopolymerization initiator may be selected from one or more of the group consisting of phosphine oxide compounds, 9-oxosulfur compounds, and benzoic acid ester compounds. For example, if the above-mentioned (D) photopolymerization initiator is a phosphine oxide compound or a 9-oxosulfur compound, the resin composition can be cured using LED light of 365 to 395 nm.

[0065] In the resin composition of the present invention, the content of (D) photopolymerization initiator may be 0.1 to 10% by weight, 0.1 to 5% by weight, or 1 to 5% by weight relative to the total composition. The composition may include solid components and solvents.

[0066] When the content of the photopolymerization initiator is 0.1% by weight or more, the photocurability of the resin composition is improved and the coating properties such as chemical resistance are also improved. On the other hand, when the content is 10% by weight or less, the light absorption of the surface of the resist film (cured coating film) is improved and the depth curing property is not easily reduced.

[0067] Photoinitiators or sensitizers can also be used in combination with the photopolymerization initiators described above. Examples of photoinitiators or sensitizers include benzoin compounds, anthraquinone compounds, 9-oxosulfur compounds, ketol compounds, benzophenone compounds, tertiary amine compounds, and ketone compounds. In particular, 9-oxosulfur compounds such as 2,4-dimethyl9-oxosulfur, 2,4-diethyl9-oxosulfur, 2-chloro9-oxosulfur, 2-isopropyl9-oxosulfur, and 4-isopropyl9-oxosulfur can be used. The inclusion of 9-oxosulfur compounds can improve the depth of curing. There are also cases where these compounds can be used as photopolymerization initiators, but they can also be used in combination with photopolymerization initiators. Furthermore, a single photoinitiator or sensitizer can be used, or two or more can be used in combination.

[0068] Furthermore, these photopolymerization initiators, photoinitiators, and sensitizers absorb specific wavelengths, thus allowing their sensitivity to decrease depending on the circumstances, thereby functioning as ultraviolet absorbers. However, they are not used solely for the purpose of increasing the sensitivity of the resin composition. By absorbing specific wavelengths of light as needed, the photoreactivity of the surface can be improved, and the accuracy of the line width or opening diameter can be improved by changing the line shape and opening of the resist pattern to vertical, conical, or inverted conical.

[0069] [(E) Inorganic filler]

[0070] The resin composition according to one embodiment of the present invention is used to improve properties such as adhesion and hardness by including an inorganic filler. Furthermore, the inorganic filler can be used as a colorant.

[0071] Inorganic fillers may be selected from one or more of the group consisting of titanium oxide, zinc oxide, carbon black, basic carbonates, basic sulfates, sulfates, zinc sulfide, antimony oxide, aluminum hydroxide, silicon oxide and barium sulfate.

[0072] For example, the manufacturing method of titanium oxide can be either the sulfuric acid process or the chlorine process, such as the chlorine process. For example, sulfuric acid may not be used in the manufacturing process. Furthermore, there are no particular limitations on the surface treatment of titanium oxide, but it can be titanium oxide treated with acids other than sulfuric acid, such as hydrochloric acid, nitric acid, phosphoric acid, or acetic acid during neutralization.

[0073] The titanium oxide can be any of the following structures: rutile, anatase, or manganese oxide. It can be used alone or in combination with two or more types. Among them, manganese oxide can be obtained by performing a chemical lithium oxide removal process on manganese oxide Li0.5TiO2.

[0074] As described above, the use of rutile titanium dioxide further improves heat resistance, reduces the likelihood of discoloration due to light exposure, and minimizes quality degradation even under harsh operating conditions. In particular, heat resistance can be improved by using rutile titanium dioxide surface-treated with aluminum oxides such as alumina. The content of rutile titanium dioxide surface-treated with aluminum oxides in the total titanium dioxide composition is, for example, 35% by mass or more, for example, 55% by mass or more, with a maximum of 100% by mass or less; that is, the total amount of titanium dioxide can also be rutile titanium dioxide surface-treated with the aforementioned aluminum oxides. Furthermore, anatase titanium dioxide has a lower hardness than rutile titanium dioxide; therefore, when using anatase titanium dioxide, the formability of the composition becomes better.

[0075] (E) In the inorganic filler, the sulfur concentration of the titanium dioxide can be less than 100 ppm or less than 50 ppm. Furthermore, commercially available titanium dioxide with a sulfur concentration of less than 100 ppm can be used, and commercially available titanium dioxide with a sulfur concentration of more than 100 ppm can be subjected to heat treatment, chemical treatment, or refining treatments such as cleaning and calcination to reduce the sulfur concentration and to adjust the formulation. Here, the sulfur included in titanium dioxide refers to all sulfur detected by analysis. This includes sulfur adsorbed on titanium dioxide and sulfur coated on titanium dioxide using impurities. Also, the sodium concentration of the titanium dioxide can be less than 100 ppm or less than 50 ppm. The lower the sodium concentration, the better. If the sodium concentration is too high, the copper substrate will be exposed to moisture due to sodium ions, which will promote corrosion or oxidation. For this reason, the sodium ion concentration can be less than 100 ppm.

[0076] Furthermore, the photosensitive resin composition of the present invention may also contain titanium oxide with a sulfur concentration of 100 ppm or more, without impairing the effects of the present invention. Examples of titanium oxide with a sulfur concentration of 100 ppm or more include Ishihara Sangyo Co., Ltd. CR-58, CR-90, R-630, and Sakai-chem Co., Ltd. R-21.

[0077] Also, it can be used as rutile-type chlorine process titanium dioxide, such as Ishihara Sangyo Co., Ltd.'s T-550, T-580, R-630, R-820, CR-50, CR-60, R-90, CR-97, or DuPont's Ti PURE R-706, R-902+, R931, Millenium Chemicals' Tiona 568, Tiona 595, Fuji Titanium Industry Co., Ltd.'s TR-600, TR-700, TR-840, and Titanium Industry Co., Ltd.'s KR-270, KR-310, KR-380, etc.

[0078] If the titanium oxide particles are too small, their flowability deteriorates; conversely, if they are too large, the insertion capability of the substrate with a smaller diameter deteriorates. Considering this, the central value of the titanium oxide particle size is in the range of 0.1 to 5 μm, for example, 0.1 to 1 μm, for example, 0.1 to 0.5 μm, and can be 0.20 μm to 0.36 μm. When the titanium oxide particle size is within the above range, stable ejection properties can be achieved. The above particle size was determined using a laser diffraction method.

[0079] (E) Among inorganic fillers, barium sulfate may include precipitated barium sulfate #100, precipitated barium sulfate #300, precipitated barium sulfate SS-50, BARIACE (BARIACE) B-30, BARIACE B-31, BARIACE B-32, BARIACE B-33, BARIACE B-34, BARIFINE (BARIFINE) BF-1, BARIFINE BF-10, BARIFINE BF-20, BARIFINE BF-40 (manufactured by Sakai Kagaku Kogyo (stock)), W-1, W-6, W-10, C300 (manufactured by Takehara Kagaku Kogyo (stock) (Takehara Kagaku Kogyo Co., Ltd.)), etc.

[0080] (E) In inorganic fillers, silicon oxide particles are not particularly limited and can be obtained by methods well known to those skilled in the art. For example, they can be manufactured by burning silicon powder using the VMC (Vap-ized Metal Combustion) method. The VMC method is as follows: a chemical salt is formed in a furnace in an oxygen-containing environment, and metal powder, which constitutes part of the desired oxide particles to form a dust cloud, is added to the chemical salt, causing detonation to obtain oxide particles. Commercially available silicon oxides include the SO series manufactured by AdMateX Corporation and the HPS series (HPS-0500, HPS-1000, HPS3500, etc.) manufactured by Toa Synthetic Co., Ltd.

[0081] (E) In inorganic fillers, carbon black can be used as a black colorant. Specifically, the particle diameter of the aforementioned carbon black can be greater than about 0 nm and less than about 30 nm, for example, it can be about 10 nm to about 30 nm. The particle diameter of the aforementioned carbon black can be obtained by measuring the diameter of the projected image when the aforementioned carbon black is projected with parallel light of a fixed direction. The particle diameter of the aforementioned carbon black satisfies the above range, thereby improving the dispersibility within the resin composition. Examples of carbon black include carbon black manufactured by Mitsubishi Chemical Corporation, M-40, M-45, M-50, MA-8, MA-100, and carbon black 1255 manufactured by Columbia Chemical Corporation.

[0082] For example, (E) there are no particular restrictions on inorganic fillers, but when using titanium dioxide, it can be used in conjunction with photopolymerization initiators that absorb light at 350 nm to 450 nm. From the point of view of coloring, it can be used in conjunction with photopolymerization initiators of phosphine oxide compounds.

[0083] In the photosensitive resin composition of the present invention, the amount of (E) inorganic filler is in the range of 1 to 30% by mass, for example, 1.5 to 25% by mass, or for example, 1.5 to 20% by mass, relative to the total amount of the resin composition. When the content of (E) inorganic filler is within the above range, it is expected to improve the physical strength and suppress the decrease in (inkjet) printability caused by the increase in viscosity or thixotropy.

[0084] [Ingredients other than these]

[0085] The resin composition of the present invention may contain one or more of the following materials as any component, as needed.

[0086] <Epoxy Resin> The epoxy resin of the present invention may be a known conventional compound having one or more epoxy groups. For example, it may be a compound having two or more epoxy groups. For example, it may be a monoepoxy compound such as butyl acrylate, propyl acrylate, acrylate (meth) acrylate, bisphenol A type epoxy resin, bisphenol S type epoxy resin, bisphenol F type epoxy resin, phenolic varnish epoxy resin, benzophenol varnish type epoxy resin, aliphatic cyclic epoxy resin, trimethylolpropane polyacrylate, phenyl-1,3-diacrylate, biphenyl-4,4'-diacrylate, 1,6-hexanediol diacrylate, ethylene glycol or propylene glycol diacrylate, sorbitol polyacrylate, tris(2,3-epoxypropyl)isocyanurate, tri(2-hydroxyethyl)isocyanurate, etc., having two or more epoxy groups in one molecule. These can be used individually or in combination of two or more, depending on the specific requirements.

[0087] <Antioxidant> The resin composition of the present invention may also contain an antioxidant. By containing an antioxidant, not only can the effect of preventing oxidative degradation of curing resins and the like and inhibiting discoloration be obtained, but also the effects of improved heat resistance and better resolution (linewidth reproducibility) can be obtained. That is, there are cases where the resolution deteriorates due to the reflection and absorption of light depending on the type of white colorant, but by containing an antioxidant, better resolution can be obtained regardless of the type of white colorant.

[0088] <Coloring agent> A coloring agent may be contained in the resin composition of the present invention.

[0089] As black colorants, in addition to carbon black, inorganic pigments such as iron(III) oxide (Fe3O4), black titanium dioxide, copper manganese black, copper chromium black, and cobalt black, as well as organic pigments such as indigo black and aniline black, can also be listed. Furthermore, other commonly used red, blue, green, and yellow pigments and dyes can be listed as other colorants.

[0090] The content of the colorant in the resin composition of the present invention is approximately 1.0 to 25.0% by mass relative to the total amount of the resin composition, for example, 2.0 to 15.0% by mass.

[0091] <Other Additives> Furthermore, other additives commonly known and used in the field of formulating electronic materials from the resin composition of the present invention may be included. Examples of other additives include thermal polymerization inhibitors, ultraviolet absorbers, plasticizers, flame retardants, antistatic agents, anti-aging agents, antibacterial and antifungal agents, defoamers, leveling agents, thickeners, flowability additives, adhesion promoters, thixotropic promoters, photoinitiators, sensitizers, curing accelerators, release agents, surface treatment agents, dispersants, dispersing aids, surface modifiers, stabilizers, and diluents.

[0092] [Hardened material and its manufacturing method]

[0093] The hardened material of the present invention can be formed by hardening the resin composition of the present invention.

[0094] The hardened material of the present invention can be suitably used in printed circuit boards and electronic components. The hardened material of the present invention can be used to form markings in subsequent processes after the process of applying solder resist to a printed circuit board. When the hardened material of the present invention is used in a flexible substrate, it exhibits excellent flexibility and can suppress peeling and cracking when folded or bent.

[0095] Furthermore, a hardened film with excellent properties such as adhesion and hardness can be formed by i) irradiating the hardened material with active energy lines and then heating and hardening it (e.g., 100-220°C) or ii) heating and hardening the material and then irradiating it with active energy lines.

[0096] <Examples> Hereinafter, the present invention will be described in detail using examples. The present invention is not limited to the following examples.

[0097] The composition of inkjet marking ink is manufactured by placing the raw materials into a container and stirring. The content of each component is the same as that recorded in Table 1 below.

[0098] Table 1. Content of each component in the composition (unit: parts by weight relative to the whole composition)

[0099] The detailed contents of each component shown in Table 1 above are as follows.

[0100] Manufacturing of Flexible Marking Ink Substrate: First, a Kapton (registered trademark) polyimide flexible substrate manufactured by Toray DuPont Ltd., measuring 100 mm in length and 150 mm in width, was prepared. Next, the inkjet marking ink composition manufactured in the examples and comparative examples was applied to the polyimide flexible substrate using a piezoelectric printhead of an inkjet printer (Microcraft MJP2013K1-DU). Subsequently, the inkjet marking ink composition coated on the polyimide flexible substrate was photocured by irradiating it with ultraviolet light using a UV LED lamp (385 nm, 395 nm) attached to the inkjet printer, with a total cumulative light intensity of 400 mJ / cm². After photocuring, a marking ink coating was manufactured by heat curing at 150°C for 60 minutes in a hot air circulating drying oven.

[0101] The inkjet marking ink compositions of the Examples and Comparative Examples were evaluated using the marking ink coating manufactured according to the above description as the subject. The evaluation results are shown in Table 2.

[0102] 1. The Hajeory test involves repeatedly bending a Hajeory cylinder twice at 180° angles. The occurrence of cracks is observed using the naked eye and an optical microscope (magnification ×200), and the number of cracks is evaluated. ◎: 0 cracks; 〇: 1 small crack; △: 1 crack; ×: 2 or more cracks.

[0103] 2. MIT Experiment

[0104] The MIT flexural fatigue testing machine (Type D, manufactured by Toyoseiki Seisakusho Co., Ltd.) was used to perform the MIT test according to JIS P8115 and evaluate the flexural properties. Under a load (0.5 kgf), the test piece was attached vertically to the clamp, and the bending was performed at a bending angle of 135° and a speed of 175 RPM. The number of reciprocating bends until fracture was measured. The flexural properties were evaluated according to the following criteria: ◎: 100 or more ○: 50 or more but less than 100 △: 10 or more but less than 50 ×: less than 10

[0105] 3. Adhesion of Marking Ink

[0106] Using a knife, make 100 (10×10) quadrilateral (□) markings at 30° angles on the surface of the marking ink film, with a width of 1 mm. After sealing with adhesive tape, peel off the tape one by one. Evaluate the adhesion by observing the shape of the peeled parts in the figure below. ◎: 5B ○: 4B △: 3B ×: 2B or less

[0107] 4. Pencil Hardness: Press a sharpened pencil from B to 9H at an angle of approximately 45° to flatten the end of the lead. Record the hardness of the pencil without any peeling of the lead film and evaluate it according to the following criteria: 6H and above: ◎ 5H and above: 0 4H and above: △ 3H and above: ×

[0108] 5. Storage Stability: The initial viscosity of the inkjet ink composition was measured, and after storage in a sealed container at 50°C for 2 weeks, the viscosity was measured again. The viscosity change was confirmed according to the following formula, and the storage stability was evaluated. Formula: (A = initial viscosity, B = viscosity after 2 weeks of storage)

[0109] The viscosity change calculated using the above formula is evaluated according to the following criteria: Viscosity change greater than 0% and less than 8%: ○ Viscosity change greater than 8% and less than 15%: △ Viscosity change greater than 15%: ×

[0110] Table 2. Evaluation Results Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Hajeory test ◎ △ ○ ○ ○ × × × × △ × × MIT Experiment ◎ ○ ◎ ◎ ○ △ × × △ △ × × Adhesion of marking ink ◎ ○ ◎ ○ ◎ ○ × × × ○ △ △ Pencil hardness ○ ○ ○ ○ ○ ○ × × × × △ △ Preservation stability ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ △ ×

[0111] It is known that the acrylic equivalent of the resin composition in Examples 1 to 5 is 160 g / eq or more and 280 g / eq or less. Therefore, when the coating film using it is folded or bent, peeling and cracking are suppressed, and the softness, adhesion and hardness are excellent.

[0112] On the other hand, when using the resin compositions of Comparative Examples 1 to 3 and 5 to 7 with an acrylic equivalent of less than 160 g / eq and the resin composition of Comparative Example 4 with an acrylic equivalent of more than 280 g / eq, it was confirmed that more cracking occurred and the bending resistance was poor, and the adhesion to the substrate of the coating was also poor.

[0113] Furthermore, it can be confirmed that Comparative Examples 1 to 3, which do not contain end-capped isocyanates, have lower strength and are prone to cracking. It can be confirmed that Comparative Examples 2 to 4, which do not contain (meth)acrylates with hydroxyl groups, have lower flexibility and adhesion. It can be confirmed by Comparative Example 4 that if the equivalence ratio (OH / NCO) exceeds 15, the crosslinking density decreases and it is difficult to demonstrate the coating strength. It can be confirmed by Comparative Examples 5 and 6 that if the equivalence ratio (OH / NCO) is less than 4, the adhesion decreases and the storage stability deteriorates. [Simplified Explanation of the Diagram]

[0029] None

Claims

1. A resin composition comprising: (A) Monofunctional (meth)acrylates; (B) Polyfunctional (meth)acrylates; (C) thermosetting resin; (D) photopolymerization initiator; and (E) inorganic filler; and the acrylic equivalent is 160 g / eq or more and 280 g / eq or less, wherein the monofunctional (meth)acrylate of (A) above includes (meth)acrylate having hydroxyl groups, and the content of the above (meth)acrylate having hydroxyl groups is 10 to 40% by weight based on the total weight of the resin composition.

2. The resin composition of claim 1, wherein the above-mentioned (A) monofunctional (meth)acrylate and (B) polyfunctional (meth)acrylate include polar functional groups capable of forming crosslinking bonds.

3. The resin composition of claim 2, wherein the polar functional group is selected from one or more of the group consisting of hydroxyl, carboxyl, amino group, amine group, carbonyl, acrylic, acrylonitrile, nitrile, vinyl, halogen, carbamate and ester groups.

4. The resin composition of claim 1, wherein the above-mentioned (A) monofunctional (meth)acrylate or (B) polyfunctional (meth)acrylate has an epoxide backbone.

5. The resin composition of claim 1, wherein, based on the total weight of the resin composition, the content of (A) monofunctional (meth)acrylate is 30 to 80 by weight.

6. The resin composition of claim 1, wherein, based on the total weight of the resin composition, the content of (B) polyfunctional (meth)acrylate is 2 to 45% by weight.

7. The resin composition of claim 1, wherein the thermosetting resin of claim (C) includes a capped isocyanate.

8. The resin composition of claim 1, wherein the (A) monofunctional (meth)acrylate includes a (meth)acrylate having hydroxyl groups, and the (C) thermosetting resin includes a capped isocyanate, wherein the isocyanate to hydroxyl group equivalent ratio is 1:4 to 1:

15.

9. The resin composition of claim 1, wherein, based on the total weight of the resin composition, (C) the content of thermosetting resin is 2 to 15% by weight.

10. The resin composition of claim 1, wherein the photopolymerization initiator (D) is selected from one or more of the group consisting of phosphine oxides, 9-oxosulfur compounds and benzoic acid esters.

11. The resin composition of claim 1, wherein the inorganic filler (E) is selected from one or more of the group consisting of titanium oxide, zinc oxide, carbon black, basic carbonate, basic sulfate, sulfate, zinc sulfide, antimony oxide, aluminum hydroxide, silicon oxide and barium sulfate.

12. A resin composition comprising: (A) Monofunctional (meth)acrylates; (B) Polyfunctional (meth)acrylates; (C) Thermosetting resins; (D) Photopolymerization initiator; and (E) Inorganic filler; wherein the above (A) monofunctional (meth)acrylate includes (meth)acrylate having hydroxyl groups, and the above (C) thermosetting resin includes end-capped isocyanate, wherein the isocyanate to hydroxyl group equivalent ratio is 1:4 to 1:15, wherein the content of the above (meth)acrylate having hydroxyl groups is 10 to 40% by weight based on the total weight of the resin composition.

13. The resin composition of any one of claims 1 to 12 is used to form a mark in a subsequent process of applying photosensitive solder resist to a printed circuit board.

14. A printed circuit board having a hardened material formed on a substrate from a resin composition of any one of claims 1 to 12.