JP7614832B2 - CURABLE RESIN COMPOSITION, DRY FILM, CURED PRODUCT, AND ELECTRONIC COMPONENT - Google Patents

Description

The present invention relates to a curable resin composition, a dry film having the curable resin composition as a resin layer, a cured product of the resin layer of the dry film, and an electronic component having the cured product.

In the manufacture of printed wiring boards, a solder resist is usually used to protect conductor circuits on a substrate from adhesion of solder, and in order to form such solder resists, curable resin compositions containing various components having various structures have been proposed.
For example, Patent Document 1 discloses a photosensitive resin composition containing a (meth)acrylic copolymer of a specific structure having a (meth)acryloyl group, a monomer having an ethylenically unsaturated bond, and a photoinitiator.

JP2004-191680

Solder resist is required to have various properties depending on the application of the printed wiring board to which it is used, one of which is heat resistance. If the solder resist does not have sufficient heat resistance, there is a risk that the solder resist itself will discolor. For example, solder resist used in wiring boards on which light-emitting elements such as light-emitting diodes (LEDs) are mounted contains a white colorant to increase the reflection efficiency of light from the LEDs and improve their efficiency of use. When the solder resist changes color from white to yellow (yellowing), the reflection efficiency of the LED light drops significantly.

After it is formed, solder resist is particularly susceptible to heat from soldering when mounting electronic components on the substrate, heat from the electronic components after mounting, and other thermal stresses, so resistance to discoloration due to such thermal stresses is an important characteristic.

However, in this regard, conventional curable resin compositions such as the photosensitive resin composition described in Patent Document 1 do not sufficiently take into consideration the heat resistance of the solder resist, particularly its resistance to thermal discoloration.

In order to solve the above problems, the inventors conducted extensive research and discovered that by combining a compound having an isocyanurate structure and two or more (meth)acryloyl groups with an epoxy resin having an isocyanurate structure in a curable resin composition, it is possible to form a cured coating film (e.g., a solder resist) with improved resistance to thermal discoloration, and thus completed the present invention.

That is, the object of the present invention is to
At least the following components (A) to (C):
(A) a compound having an isocyanurate structure and two or more (meth)acryloyl groups,
It has been found that this problem can be solved by a curable resin composition containing (B) an epoxy resin having an isocyanurate structure, and (C) a photopolymerization initiator.
Among these, a preferred embodiment of the present invention relates to the above curable resin composition further comprising (D) an antioxidant having an isocyanurate structure.
A further preferred embodiment relates to the above curable resin composition further comprising (E) a white colorant.
Yet another preferred embodiment relates to the above curable resin composition, which further contains at least one of a carboxyl group-containing fluororesin and a carboxyl group-containing copolymer resin that does not contain fluorine atoms.
Yet another preferred embodiment relates to the above curable resin composition further containing at least one of silica having a specific surface area of 10 m ² /g or more and less than 100 ^{m 2 /g, and silica having a specific surface area of 100 m 2} /g or more and less than 300 m ² /g.
Another aspect of the present invention relates to a dry film having the above-mentioned curable resin composition as a resin layer, a cured product of the above-mentioned curable resin composition or the resin layer of the dry film, and an electronic component having the cured product.

The present invention provides a cured product (cured coating film) with higher heat resistance, and a curable resin composition capable of forming the cured product. The cured product is therefore highly resistant to discoloration due to heat, and can therefore be more suitably used as a solder resist layer, in particular as a white solder resist layer for wiring boards on which LEDs are mounted.

The high thermal discoloration resistance of the cured product obtained from the curable resin composition of the present invention can basically be achieved by using (A) a compound having an isocyanurate structure and two or more (meth)acryloyl groups in combination with (B) an epoxy resin having an isocyanurate structure.

In the present invention, the thermal discoloration resistance can also be expressed as the degree of change in color tone of a cured coating film formed from a curable resin composition before and after thermal stress (color difference: ΔE). It can be said that the smaller ΔE is, the higher the thermal discoloration resistance is, and the larger ΔE is, the lower the thermal discoloration resistance is.
For example, ΔE can be calculated as the amount of color change from the initial value by subjecting a cured product that has been subjected to coating, drying, exposure, development and curing treatment of a curable resin composition to a heat treatment for 10 seconds at a peak top temperature of 285°C.

The curable resin composition of the present invention also has good long-term storage stability. Therefore, it has the advantage that the quality of the curable resin composition can be maintained even after it has been transported for a long period of time, for example, when it is transported overseas by ship.

The components that make up the curable resin composition of the present invention are described below.

[(A) Compound Having an Isocyanurate Structure and Two or More (Meth)acryloyl Groups]
(A) The compound having an isocyanurate structure and two or more (meth)acryloyl groups has an isocyanurate ring and two or more (meth)acryloyl groups in its unit structure.
The compound (A) may, for example, be a difunctional or trifunctional (meth)acrylate.
Among these, as those having a bifunctional (meth)acrylate, ethoxylated isocyanuric acid di(meth)acrylate or propoxylated isocyanuric acid di(meth)acrylate is preferred.
As the trifunctional (meth)acrylate, ethoxylated isocyanuric acid tri(meth)acrylate or propoxylated isocyanuric acid tri(meth)acrylate is preferred.
Furthermore, caprolactone modified products of these are also preferred.

More preferred as the above (A) compound having an isocyanurate structure and two or more (meth)acryloyl groups is ethoxylated isocyanuric acid tri(meth)acrylate. Commercially available products of (A) compound having an isocyanurate structure and two or more (meth)acryloyl groups include M-215, M-313, and M-315 manufactured by Toagosei Co., Ltd., A-9300, A-9300-1CL, and A-9300YN manufactured by Shin-Nakamura Chemical Co., Ltd., Photomer 4356 manufactured by IGM Resins, and FA-731A manufactured by Hitachi Chemical Co., Ltd.

In the present invention, the content of (A) the compound having an isocyanurate structure and two or more (meth)acryloyl groups is preferably 3 to 25% by mass based on the total solid content of the entire composition. In particular, when the curable resin composition of the present invention contains a white colorant, the content of (A) the compound having an isocyanurate structure and two or more (meth)acryloyl groups is preferably 3 to 10% by mass, more preferably 5 to 7% by mass. When it is 3 to 25% by mass, not only is the thermal discoloration resistance of the obtained cured product good, but the strength of the cured coating film is good, the viscosity of the composition is appropriate, and the coatability, etc. can be improved.

[(B) Epoxy resin having an isocyanurate structure]
The curable resin composition of the present invention contains an epoxy resin having an isocyanurate structure, in which a nitrogen atom in the isocyanurate structure is bonded to an epoxy group via an alkylene chain. In particular, an epoxy resin having an alkylene chain with 2 or more carbon atoms is preferred. When the alkylene chain has 2 to 5 carbon atoms, the resulting cured product has good resistance to thermal discoloration.

（式中、
Ｒ_１、Ｒ_２およびＲ_３は、それぞれ独立して、炭素数２～５のアルキレン基を表し、
ｎは０または１であるが、但し、全てのｎが同時に０を表すことはない） The epoxy resin (B) having an isocyanurate structure used in the present invention preferably has a structure represented by the following formula (I).

(Wherein,
R ₁ , R ₂ and R ₃ each independently represent an alkylene group having 2 to 5 carbon atoms;
n is 0 or 1, but all n's are not 0 at the same time.

Among these, particularly preferred is a structure in which R ₁ , R ₂ and R ₃ simultaneously represent an alkylene group having 3 carbon atoms and n simultaneously represents 1 in the formula.

Specific examples of epoxy resins having an isocyanurate structure (B) that are preferably used in the present invention include TEPIC (registered trademark)-VL and TEPIC (registered trademark)-FL (both manufactured by Nissan Chemical Industries, Ltd.).

The content of such epoxy resin having an isocyanurate structure (B) is preferably 30 to 70 mass% relative to 100 mass parts of the compound having an isocyanurate structure and two or more (meth)acryloyl groups (A). In particular, when the curable resin composition of the present invention contains a white colorant (E), the content of the compound having an isocyanurate structure and two or more (meth)acryloyl groups (A) is preferably 48 to 68 mass parts. If the content is within the range of 30 to 70 mass%, the thermal discoloration resistance of the obtained cured product is good, and the storage stability of the curable resin composition is also improved.

[(C) Photopolymerization initiator]
As the (C) photopolymerization initiator, any photopolymerization initiator known as a photopolymerization initiator or a photoradical generator can be used. For example, bis-(2,6-dichlorobenzoyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis-(2,6-dimethoxybenzoyl) )phenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide, bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and other bisacylphosphine oxides; 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, monoacylphosphine oxides such as methyl benzoylphenylphosphine ester, 2-methylbenzoyldiphenylphosphine oxide, isopropyl pivaloylphenylphosphine ester, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide; 1-hydroxy-cyclohexyl phenyl ketone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl )-benzyl]phenyl}-2-methyl-propan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one and other hydroxyacetophenones; benzoin, benzil, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, benzoin n-butyl ether and other benzoins; benzoin alkyl ethers; benzophenone, p-methylbenzophenone, Michler's ketone, methylbenzophenone, 4,4'-dichlorobenzophenone, Benzophenones such as 4,4'-bisdiethylaminobenzophenone; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]- Acetophenones such as 1-[4-(4-morpholinyl)phenyl]-1-butanone and N,N-dimethylaminoacetophenone; thioxanthones such as thioxanthone, 2-ethylthioxanthone, 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, and 2,4-diisopropylthioxanthone; anthraquinone, chloroanthraquinone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, anthraquinones such as araquinone, 2-amyl anthraquinone, and 2-amino anthraquinone; ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal; benzoic acid esters such as ethyl-4-dimethylaminobenzoate, 2-(dimethylamino)ethyl benzoate, and p-dimethylbenzoic acid ethyl ester; 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1- Examples of the photopolymerization initiator include oxime esters such as (O-acetyloxime); titanocenes such as bis(η5-2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl)titanium and bis(cyclopentadienyl)-bis[2,6-difluoro-3-(2-(1-pyr-1-yl)ethyl)phenyl]titanium; phenyl disulfide 2-nitrofluorene, butyroin, anisoin ethyl ether, azobisisobutyronitrile, and tetramethylthiuram disulfide. One type of photopolymerization initiator may be used alone, or two or more types may be used in combination.

The content of (C) the photopolymerization initiator is preferably 5 to 20 parts by mass, and more preferably 10 to 20 parts by mass, per 100 parts by mass of (A) the compound having an isocyanurate structure and two or more (meth)acryloyl groups. If it is within the range of 5 to 20 parts by mass, the surface curing property is good, and good resolution is obtained with little halation.

（式中、
基Ｒ_４、Ｒ_５およびＲ_６は、それぞれ独立して、水素原子を表すか、または、水酸基および炭素原子数１～１０の炭化水素基から成る群より選択される少なくとも１種の置換基により置換されていてもよい脂肪族炭化水素基あるいは芳香族炭化水素基を表し、且つ、
式中の窒素原子と、基Ｒ_４、Ｒ_５またはＲ_６とは、直接結合していてもよく、または、炭素原子数１～１０のアルキレン基を介して結合していてもよい） [(D) Antioxidant having an isocyanurate structure]
The curable resin composition of the present invention may further contain (D) an antioxidant having an isocyanurate structure, which can provide the effect of further improving the resistance of the cured coating film to thermal discoloration.
A preferred example of such an antioxidant having an isocyanurate structure (D) is one represented by the following formula (II).

(Wherein,
Groups R ₄ , R ₅ and R ₆ each independently represent a hydrogen atom, or an aliphatic or aromatic hydrocarbon group which may be substituted with at least one substituent selected from the group consisting of a hydroxyl group and a hydrocarbon group having 1 to 10 carbon atoms; and
The nitrogen atom in the formula and the group R ₄ , R ₅ or R ₆ may be bonded directly or via an alkylene group having 1 to 10 carbon atoms.

A more preferred antioxidant having an isocyanurate structure (D) is one in which in formula (II), the groups R ₄ , R ₅ and R ₆ each represent a phenyl group substituted with one hydroxyl group and 1 to 3 hydrocarbon groups having 1 to 4 carbon atoms, and each nitrogen atom is bonded to the group R ₄ , R ₅ or R ₆ via an alkylene group having 1 to 3 carbon atoms.

A particularly preferred antioxidant having an isocyanurate structure (D) is 1,3,5-tris(3,5-di-tert-butyl)-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (product name: Irganox 3114; manufactured by BASF Japan Ltd.), which is represented by the following formula (II'): Other commercially available antioxidants having an isocyanurate structure (D) include Cyanox 1790 manufactured by Nippon Cytec Industries Co., Ltd. and Adeka STAB AO-20 manufactured by Adeka Corporation.

The content of (D) the antioxidant having an isocyanurate structure is preferably 1 to 8 mass% relative to 100 mass parts of (A) the compound having an isocyanurate structure and two or more (meth)acryloyl groups. If it is in the range of 1 to 8 mass%, the thermal discoloration resistance of the cured coating film is further improved.

[(E) White colorant]
When the curable resin composition of the present invention is used as a solder resist for a printed wiring board for LEDs, for example, it may contain a white colorant, which can increase the reflectance of the cured coating film and improve the efficiency of the use of LED light.
Examples of the (E) white colorant include titanium oxide, zinc oxide, potassium titanate, zirconium oxide, antimony oxide, white lead, zinc sulfide, and lead titanate. Titanium oxide is preferably used because it has a high effect of inhibiting discoloration due to heat.

Titanium oxide may be of any of the following structures: rutile, anatase, or ramsdellite. One type may be used alone, or two or more types may be used in combination. Ramsdellite titanium oxide can be obtained by subjecting ramsdellite Li0.5TiO2 to lithium desorption treatment through chemical oxidation.

Among the above, the use of rutile-type titanium oxide is preferred because it can further improve the heat resistance of the cured coating film. In particular, the use of rutile-type titanium oxide surface-treated with aluminum oxide such as alumina or silica can further improve the reflectance and heat resistance of the cured coating film.
Moreover, a further surface treatment can be performed after the surface treatment. In particular, by performing a surface treatment with alumina and then a further surface treatment with zirconia, the reflectance can be further improved.
Examples of the rutile-type titanium oxide surface-treated with aluminum oxide include CR-58, which is a rutile-type chlorine-process titanium oxide manufactured by Ishihara Sangyo Kaisha, Ltd., and R-630, which is a rutile-type sulfuric acid-process titanium oxide manufactured by the same company. It is also preferable to use rutile-type titanium oxide surface-treated with silicon oxide, and in this case too, the heat resistance can be further improved. It is also preferable to use rutile-type titanium oxide surface-treated with both aluminum oxide and silicon oxide, and examples of the rutile-type chlorine-process titanium oxide manufactured by Ishihara Sangyo Kaisha, Ltd. include CR-90, which is a rutile-type chlorine-process titanium oxide manufactured by Ishihara Sangyo Kaisha, Ltd.

The amount of such (E) white colorant blended is preferably in the range of 750 to 950 parts by mass, more preferably in the range of 800 to 900 parts by mass, per 100 parts by mass of (A) the compound having an isocyanurate structure and two or more (meth)acryloyl groups.

[Carboxyl group-containing resin]
It is preferable that the curable resin composition of the present invention further contains at least one of a carboxyl group-containing fluororesin and a carboxyl group-containing resin not containing a fluorine atom.
As the fluororesin containing a carboxyl group, a known fluororesin containing a carboxyl group can be used. A fluororesin is a polymer or oligomer having at least one fluorine atom. The presence of a carboxyl group can make the curable resin composition alkaline developable, and the presence of a fluorine atom can improve resistance to thermal discoloration.
In order to make the curable resin composition of the present invention photocurable and to improve the development resistance, the composition may have an ethylenically unsaturated bond in the molecule in addition to the carboxyl group and the fluorine atom. The ethylenically unsaturated double bond may be derived from acrylic acid, methacrylic acid, or a derivative thereof.

Specific examples of carboxyl group-containing fluororesins that can be used in the curable resin composition of the present invention include the compounds (which may be either oligomers or polymers) listed below. Note that the "fluorine-substituted compound" described below refers to a compound in which one or more hydrogen atoms other than the hydrogen atoms that constitute the functional groups of a specific compound are substituted with fluorine.

(1) A carboxyl group-containing fluororesin obtained by copolymerizing an unsaturated carboxylic acid such as (meth)acrylic acid with a fluorine-substituted compound containing an unsaturated group such as styrene, α-methylstyrene, alkyl (meth)acrylate (wherein the alkyl has, for example, 2 to 15 carbon atoms, preferably 2 to 8 carbon atoms), or isobutylene.

(2) A carboxyl group-containing urethane resin obtained by polyaddition reaction of a diisocyanate such as an aliphatic diisocyanate, a branched aliphatic diisocyanate, an alicyclic diisocyanate, or an aromatic diisocyanate with a carboxyl group-containing dialcohol compound such as dimethylolpropionic acid or dimethylolbutanoic acid, and a diol compound such as a polycarbonate polyol, a polyether polyol, a polyester polyol, a polyolefin polyol, an acrylic polyol, a bisphenol A alkylene oxide adduct diol, or a compound having a phenolic hydroxyl group or an alcoholic hydroxyl group, in which at least one of the raw materials described is a fluorine-substituted product, and which contains a carboxyl group and a urethane bond.

(3) A urethane resin containing terminal carboxyl groups, which is obtained by reacting an acid anhydride with the terminal of a urethane resin obtained by polyaddition reaction of a diisocyanate compound such as an aliphatic diisocyanate, a branched aliphatic diisocyanate, an alicyclic diisocyanate, or an aromatic diisocyanate with a diol compound such as a polycarbonate polyol, a polyether polyol, a polyester polyol, a polyolefin polyol, an acrylic polyol, a bisphenol A alkylene oxide adduct diol, or a compound having a phenolic hydroxyl group or an alcoholic hydroxyl group, and at least one of the raw materials described is a fluorine-substituted product, and which contains a carboxyl group and a urethane bond.

(4) A photosensitive carboxyl group-containing urethane resin obtained by polyaddition reaction of diisocyanate with (meth)acrylate or its partial acid anhydride modified product of bifunctional epoxy resin such as bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bixylenol type epoxy resin, biphenol type epoxy resin, etc., a carboxyl group-containing dialcohol compound, and a diol compound, in which at least one of the described raw materials is a fluorine-substituted product, and which contains a carboxyl group and a urethane bond.

(5) A fluororesin containing terminal (meth)acrylated carboxyl groups and urethane bonds, which is produced by adding a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as hydroxyalkyl (meth)acrylate, during the synthesis of the resin (2) or (4) above.

(6) A fluororesin containing terminal (meth)acrylated carboxyl groups and urethane bonds, which is produced by adding a compound having one isocyanate group and one or more (meth)acryloyl groups in the molecule, such as an equimolar reactant of isophorone diisocyanate and pentaerythritol triacrylate, during the synthesis of the resin (2) or (4) above.

(7) A photosensitive carboxyl group-containing fluororesin obtained by reacting a fluorine-substituted polyfunctional epoxy resin as described below with (meth)acrylic acid and adding a dibasic acid anhydride such as phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride to the hydroxyl groups present in the side chains.

(8) A photosensitive carboxyl group-containing fluororesin obtained by reacting a fluorine-substituted polyfunctional epoxy resin, in which the hydroxyl groups of a bifunctional epoxy resin have been further epoxidized with epichlorohydrin, with (meth)acrylic acid, and then adding a dibasic acid anhydride to the resulting hydroxyl groups.

(9) A fluororesin containing carboxyl groups and ester bonds, which is obtained by reacting a fluorine-substituted polyfunctional oxetane resin as described below with a dicarboxylic acid and adding a dibasic acid anhydride to the resulting primary hydroxyl groups.

(10) A carboxyl group-containing photosensitive fluororesin obtained by reacting a fluorine-substituted compound having multiple phenolic hydroxyl groups in one molecule with an alkylene oxide such as ethylene oxide or propylene oxide, reacting the reaction product obtained with an unsaturated group-containing monocarboxylic acid, and reacting the resulting reaction product with a polybasic acid anhydride.

(11) A carboxyl group-containing photosensitive fluororesin obtained by reacting a fluorine-substituted compound having multiple phenolic hydroxyl groups in one molecule with a cyclic carbonate compound such as ethylene carbonate or propylene carbonate, reacting the reaction product obtained with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

(12) A carboxyl group-containing photosensitive fluororesin obtained by reacting a fluorine-substituted epoxy compound having multiple epoxy groups in one molecule with a compound having at least one alcoholic hydroxyl group and one phenolic hydroxyl group in one molecule, such as p-hydroxyphenethyl alcohol, and an unsaturated group-containing monocarboxylic acid, such as (meth)acrylic acid, and then reacting the alcoholic hydroxyl group of the resulting reaction product with a polybasic acid anhydride, such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, or adipic acid.

(13) A photosensitive carboxyl group-containing fluororesin obtained by further adding a compound having one epoxy group and one or more (meth)acryloyl groups in the molecule, such as glycidyl (meth)acrylate, α-methylglycidyl (meth)acrylate, etc., to any of the resins (1) to (12) above.

The above-mentioned fluorine-substituted compounds can be obtained by fluorinating a given compound. The fluorination method may be a known method, such as low-temperature fluorination, catalytic fluorination, aqueous solution fluorination, liquid-phase fluorination, solid-phase fluorination, or gas-phase fluorination.

Specific examples of carboxyl group-containing fluororesins that can be used include carboxyl group-containing fluororesins manufactured by Shin-Nakamura Chemical (product names: TIF-1, TIF-2, TIF-3).

The amount of the carboxyl group-containing fluororesin as described above is preferably 135 to 360 parts by mass, more preferably 150 to 300 parts by mass, per 100 parts by mass of (A) the compound having an isocyanurate structure and two or more (meth)acryloyl groups. When the amount is 135 to 300 parts by mass, the coating strength is good, the viscosity of the composition is appropriate, and the coatability, etc. can be improved.

It is preferable that the curable resin composition of the present invention further contains a carboxyl group-containing resin other than the above-mentioned carboxyl group-containing fluororesin, that is, a carboxyl group-containing resin that does not contain fluorine atoms. By containing a carboxyl group-containing resin that does not contain fluorine atoms, the developability is further improved.

As the fluorine atom-free carboxyl group-containing resin, a known resin containing a carboxyl group can be used. From the viewpoint of making the curable resin composition of the present invention photocurable and of developing resistance, it is preferable that the resin has an ethylenically unsaturated bond in the molecule in addition to the carboxyl group, but it is also possible to use only a carboxyl group-containing resin that does not have an ethylenically unsaturated double bond. The ethylenically unsaturated double bond is preferably derived from acrylic acid or methacrylic acid or a derivative thereof.

Specific examples of carboxyl group-containing resins that can be used in the curable resin composition of the present invention include the compounds (which may be either oligomers or polymers) listed below.

(1) A carboxyl group-containing copolymer resin obtained by copolymerizing an unsaturated carboxylic acid such as (meth)acrylic acid with an unsaturated group-containing compound such as styrene, α-methylstyrene, lower alkyl (meth)acrylate, or isobutylene.

(2) Carboxyl group-containing urethane resins obtained by polyaddition reaction of diisocyanates such as aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates with carboxyl group-containing dialcohol compounds such as dimethylolpropionic acid and dimethylolbutanoic acid, and diol compounds such as polycarbonate polyols, polyether polyols, polyester polyols, polyolefin polyols, acrylic polyols, bisphenol A alkylene oxide adduct diols, and compounds having phenolic hydroxyl groups and alcoholic hydroxyl groups.

(3) A urethane resin containing terminal carboxyl groups, which is obtained by reacting an acid anhydride with the terminal of a urethane resin obtained by polyaddition reaction of a diisocyanate compound such as an aliphatic diisocyanate, a branched aliphatic diisocyanate, an alicyclic diisocyanate, or an aromatic diisocyanate with a diol compound such as a polycarbonate polyol, a polyether polyol, a polyester polyol, a polyolefin polyol, an acrylic polyol, a bisphenol A alkylene oxide adduct diol, or a compound having a phenolic hydroxyl group or an alcoholic hydroxyl group.

(4) Photosensitive carboxyl group-containing urethane resins obtained by polyaddition reaction of diisocyanates with (meth)acrylates of bifunctional epoxy resins such as bisphenol A type epoxy resins, hydrogenated bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, bixylenol type epoxy resins, and biphenol type epoxy resins, or their partial acid anhydride modifications, carboxyl group-containing dialcohol compounds, and diol compounds.

(5) A carboxyl group-containing urethane resin that is (meth)acrylated at the terminal by adding a compound having one hydroxyl group and one or more (meth)acryloyl groups in the molecule, such as hydroxyalkyl (meth)acrylate, during the synthesis of the resin (2) or (4) above.

(6) A carboxyl group-containing urethane resin that is (meth)acrylated at the terminal by adding a compound having one isocyanate group and one or more (meth)acryloyl groups in the molecule, such as an equimolar reactant of isophorone diisocyanate and pentaerythritol triacrylate, during the synthesis of the resin (2) or (4) above.

(7) A photosensitive carboxyl group-containing resin obtained by reacting a multifunctional epoxy resin as described below with (meth)acrylic acid and adding a dibasic acid anhydride such as phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride to the hydroxyl groups present in the side chains.

(8) A photosensitive carboxyl group-containing resin obtained by reacting a polyfunctional epoxy resin in which the hydroxyl groups of a bifunctional epoxy resin have been further epoxidized with epichlorohydrin with (meth)acrylic acid, and then adding a dibasic acid anhydride to the resulting hydroxyl groups.

(9) A carboxyl group-containing polyester resin obtained by reacting a polyfunctional oxetane resin as described below with a dicarboxylic acid and adding a dibasic acid anhydride to the resulting primary hydroxyl groups.

(10) A carboxyl group-containing photosensitive resin obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with an alkylene oxide such as ethylene oxide or propylene oxide, reacting the reaction product obtained with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

(11) A photosensitive carboxyl group-containing resin obtained by reacting a compound having multiple phenolic hydroxyl groups in one molecule with a cyclic carbonate compound such as ethylene carbonate or propylene carbonate, reacting the reaction product obtained with an unsaturated group-containing monocarboxylic acid, and then reacting the resulting reaction product with a polybasic acid anhydride.

(12) A photosensitive carboxyl group-containing resin obtained by reacting an epoxy compound having multiple epoxy groups in one molecule with a compound having at least one alcoholic hydroxyl group and one phenolic hydroxyl group in one molecule, such as p-hydroxyphenethyl alcohol, and an unsaturated group-containing monocarboxylic acid, such as (meth)acrylic acid, and then reacting the alcoholic hydroxyl group of the resulting reaction product with a polybasic acid anhydride, such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, or adipic acid.

(13) A photosensitive carboxyl group-containing resin obtained by further adding a compound having one epoxy group and one or more (meth)acryloyl groups in the molecule, such as glycidyl (meth)acrylate, α-methylglycidyl (meth)acrylate, etc., to any of the resins (1) to (12) above.

The above-mentioned carboxyl group-containing fluororesin and fluorine-free carboxyl group-containing resin each have many carboxyl groups on the side chains of the backbone polymer, making development with a dilute alkaline aqueous solution possible.

The acid value of the carboxyl group-containing fluororesin and the fluorine-free carboxyl group-containing resin is preferably in the range of 20 to 200 mgKOH/g, more preferably in the range of 40 to 150 mgKOH/g. When the acid value of the carboxyl group-containing resin is 20 mgKOH/g or more, the adhesion of the coating film is good and alkaline development is good. On the other hand, when the acid value is 200 mgKOH/g or less, dissolution of the exposed area by the developer can be suppressed, so that the lines are prevented from becoming thinner than necessary, and in some cases, the exposed area and the unexposed area are prevented from being dissolved and peeled off by the developer without distinction, and the cured film pattern can be well drawn.

The mass average molecular weight of the carboxyl group-containing fluororesin and the fluorine-free carboxyl group-containing resin varies depending on the resin skeleton, but is preferably in the range of 2,000 to 150,000, more preferably 5,000 to 100,000. When the mass average molecular weight is 2,000 or more, the tack-free performance is good, the moisture resistance of the coating film after exposure is good, and the film loss during development is suppressed, and a decrease in resolution can be suppressed. On the other hand, when the mass average molecular weight is 150,000 or less, the developability is good and the storage stability is also excellent.
In this specification, (meth)acrylate is a term that collectively refers to acrylate, methacrylate, and mixtures thereof, and the same applies to other similar expressions.

When a fluorine-free carboxyl group-containing resin is contained, its amount is preferably the same as or less than that of the carboxyl group-containing fluororesin. Specifically, it is preferably 100 to 250 parts by mass, more preferably 100 to 200 parts by mass, per 100 parts by mass of (A) the compound having an isocyanurate structure and two or more (meth)acryloyl groups. When it is 100 to 250 parts by mass, the coating strength is good, the viscosity of the composition is appropriate, and the coatability and the like can be improved.
The mass ratio of the carboxyl group-containing fluororesin to the carboxyl group-containing resin not containing fluorine atoms is, for example, 95:5 to 50:50, preferably 90:10 to 60:40.

[silica]
The curable resin composition of the present invention preferably further contains silica in order to suppress the separation of the blending components in the curable resin composition and further improve its long-term storage stability.In this case, at least one of silica having a relatively large specific surface area and silica having a smaller specific surface area can be used.Or, it is preferable to use these two types of silica in combination in order to enhance the above effect.

In the present invention, the silica having a relatively large specific surface area preferably has a specific surface area of 100 m ² /g or more and less than 300 m ² /g. The amount of the silica having a relatively large specific surface area is preferably 1 to 20 parts by mass relative to 100 parts by mass of (A) the compound having an isocyanurate structure and two or more (meth)acryloyl groups. On the other hand, the silica having a relatively small specific surface area preferably has a specific surface area of 10 m ² /g or more and less than 100 m ² /g. The amount of the silica having a relatively small specific surface area is preferably 5 to 20 parts by mass relative to 100 parts by mass of (A) the compound having an isocyanurate structure and two or more (meth)acryloyl groups.
The compounding ratio of the silica having a relatively large specific surface area to the silica having a relatively small specific surface area is preferably 1:3 to 1:6 on a part by mass basis, because the storage stability of the composition is improved when the ratio is within this range.
The specific surface area can be measured by the BET method. More specifically, for example, a method can be adopted in which the specific surface area is actually measured by the BET single point method using a fully automatic BET specific surface area measuring device Massorb HM-1201 manufactured by Mountech Co., Ltd.

The silica used in the present invention may be ground synthetic or natural crystalline silica, ground fused silica, or spherical fused silica, or synthetic spherical silica, or synthetic fine silica.

Synthetic silica, i.e., hydrous amorphous silicon dioxide ( _SiO2.nH2O ), is produced by reacting _a sodium silicate solution (water glass) with sulfuric acid in a reaction tank, and the shape and particle size can be controlled according to the reaction conditions to produce synthetic spherical silica or synthetic fine powder silica.

Examples of silica that may be preferably used in the present invention include Aerosil 90, Aerosil 130, Aerosil 150, Aerosil 200, Aerosil 225, Aerosil 300, Aerosil 380, Aerosil OX50, Aerosil TT600, Aerosil R104, Aerosil R106, Aerosil R202, Aerosil R711, Aerosil R805, Aerosil R812, Aerosil R816, Aerosil R972, Aerosil R974, Aerosil R7200, Aerosil R8200, Aerosil R9200 (manufactured by Nippon Aerosil Co., Ltd.), ACEMATT 82, ACEMATT HK125, ACEMATT HK400, ACEMATT HK460, ACEMATT TS100, ACEMATT 82 (manufactured by EVONIK DEGUSSA) Synthetic fine silica such as E-200A, E-220A, K-500, E-1009, E-1011, E-1030, E-150J, E-170, E-200, E-220, E-743, E-974, E-75, HD, HD-2, L-250, L-300, G-300, SS-10, SS-50, SS-30P, SS-30V, SS-30X, SS-50, and SS-70 (manufactured by Tosoh Silica Corporation), FUSELEX RD-8, FUSELEX RD-8AL, FUSELEX RD-120, FUSELEX MCF-200C, FUSELEXGP-200TC, FUSELEX Fused ground silica such as TZ-20, FUSELEX ZA-30C, FUSELEX E-1, FUSELEX E-2, FUSELEX AS-1, FUSELEX X (manufactured by Tatsumori Co., Ltd.), FS-3DC, FS-5DC (manufactured by Denka Co., Ltd.), FB-5D, FB-12D, FB-20D, FB-105, FB-940, FB-9454, FB-950, FB-105FC, FB-870FC, FB-875FC, FB-9454FC, FB-950FC, FB-300FC, FB-105 FD, FB-970FD, FB-975FD, FB-950FD, FB-300FD, FB-400FD, FB-7SDC, FB-5SDC, FB-3SDC, FB-74 X, FB-25SX, FB-35X, FB-302X, FB-105X, FB-940X, FB-950X, FB-105XFC, FB-950XFC, FB-100XF D, FB-950XFD, FB-7SDX, FB-5SDX, FB-3SDX (manufactured by Denka Co., Ltd.), MSR-2212, MSR-25, MSR-3512, MSR-2212M4, MSV-2212N, MSV-2212NH, MSV-2507NH, MSV-3512N, MSV-3512NH, MSS-7, MSS-6, EXR-4, E Fused spherical silica such as XR-3, AC-5VLD, B-21, A-21, MP-15EF, AC-5V, and MP-8FS (manufactured by Tatsumori Co., Ltd.); synthetic spherical silica such as SO-E1, SO-E2, SO-E3, SO-E5, SO-E6, SO-C1, SO-C2, SO-C3, SO-C5, and SO-C6 (manufactured by Admatechs Co., Ltd.); CRYSTALITE Examples of crystalline crushed silica include CRYSTALITE 3K, CRYSTALITE 3K-S, CRYSTALITE C, CRYSTALITE TNC-1, CRYSTALITE NX-7, CRYSTALITE SMT-10, CRYSTALITE CMC-12S, CRYSTALITE XJ-7, CRYSTALITE C-BASE-1, CRYSTALITE A-1, CRYSTALITE A-A, and CRYSTALITE VX-S2 (manufactured by Tatsumori Co., Ltd.).

[Bifunctional (meth)acrylate monomer]
It is preferred that the curable resin composition of the present invention further contains a difunctional (meth)acrylate monomer in order to further enhance the thermal discoloration resistance of the cured coating film.
Examples of such bifunctional (meth)acrylate monomers include 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol acrylate, 1,10-decanediol diacrylate, and 1,16-hexadecanediol diacrylate.
Examples of commercially available products include HDDA (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), A-NOD-N (manufactured by Shin-Nakamura Chemical Co., Ltd.), B1065 (manufactured by Tokyo Chemical Industry Co., Ltd.), Viscoat #195 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), and A-DOD-N (manufactured by Shin-Nakamura Chemical Co., Ltd.).

The amount of the bifunctional (meth)acrylate monomer is preferably 5 to 65 parts by mass per 100 parts by mass of (A) the compound having an isocyanurate structure and two or more (meth)acryloyl groups. The curable resin composition of the present invention may contain a monofunctional (meth)acrylate monomer or a trifunctional or higher functional (meth)acrylate monomer as necessary.

[Other antioxidants]
In order to further enhance the thermal discoloration resistance of the cured product, the curable resin composition of the present invention may, of course, further contain an antioxidant other than the antioxidant (D) having an isocyanurate structure.
Examples of such antioxidants include hydroquinone, 4-tert-butylcatechol, 2-t-butylhydroquinone, hydroquinone monomethyl ether, 2,6-di-t-butyl-p-cresol, 2,2-methylene-bis-(4-methyl-6-t-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4 phenol-based compounds such as bis(2,2,6,6-hydroxybenzyl)benzene; quinone-based compounds such as methaquinone and benzoquinone; amine-based compounds such as bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate and phenothiazine; phosphorus-based compounds such as triphenyl phosphite; and sulfur-based compounds such as pentaerythritol tetralauryl thiopropionate, dilauryl thiodipropionate, and distearyl 3,3′-thiodipropionate.
Commercially available products include, for example, ADK STAB AO-30, ADK STAB AO-330, ADK STAB AO-20, ADK STAB LA-77, ADK STAB LA-57, ADK STAB LA-67, ADK STAB LA-68, ADK STAB LA-87 (all of which are product names manufactured by ADEKA CORPORATION), IRGANOX 1010, IRGANOX 1035, IRGANOX 1076, IRGANOX 1135, TINUVIN 111FDL, TINUVIN 123, TINUVIN 144, TINUVIN 152, TINUVIN 292, TINUVIN 5100 (all trade names, manufactured by BASF Japan Ltd.), Adeka STAB TPP (trade name, manufactured by ADEKA Corporation), Mark AO-412S (trade name, manufactured by ADEKA Corporation), Sumilizer TPS (trade name, manufactured by Sumitomo Chemical Co., Ltd.), and the like.
When such an antioxidant is used in combination with (D) an antioxidant having an isocyanurate structure, it is preferably blended in a mass ratio of 0.5 to 3, and more preferably a mass ratio of 0.5 to 2, per 1 part by mass of (D) the antioxidant having an isocyanurate structure.

[Organic solvent]
The curable resin composition of the present invention may contain an organic solvent for the purpose of adjusting the viscosity when preparing the composition or when applying it to a substrate or a carrier film. Examples of the organic solvent include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, diethylene glycol monomethyl ether acetate, and tripropylene glycol monomethyl ether; esters such as ethyl acetate, butyl acetate, butyl lactate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and propylene carbonate; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, and solvent naphtha. Known and commonly used organic solvents can be used. These organic solvents may be used alone or in combination of two or more kinds.

[Other ingredients]
The curable resin composition of the present invention may further contain other additives that are known and commonly used in the field of electronic materials, if necessary. Examples of such additives include thermal polymerization inhibitors, ultraviolet absorbers, silane coupling agents, plasticizers, flame retardants, antistatic agents, antiaging agents, antibacterial and antifungal agents, defoamers, leveling agents, thickeners, adhesion agents, photoinitiator assistants, sensitizers, thermoplastic resins, organic fillers, release agents, surface treatment agents, dispersants, dispersion assistants, surface modifiers, stabilizers, and phosphors.

[Dry film]
The curable resin composition of the present invention may be used in the form of a dry film or in the form of a liquid. When used in the form of a liquid, it may be a one-component type or a two-component or more type.
The dry film of the present invention has a resin layer obtained by applying and drying the curable resin composition of the present invention on a carrier film. When forming a dry film, first, the curable resin composition of the present invention is diluted with the organic solvent to adjust the viscosity to an appropriate level, and then coated on the carrier film to a uniform thickness using a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, spray coater, or the like. Thereafter, the applied composition is usually dried at a temperature of 50 to 130° C. for 1 to 30 minutes to form a resin layer. There is no particular restriction on the coating thickness, but it is generally appropriately selected within the range of 10 to 150 μm, preferably 20 to 60 μm, in terms of the film thickness after drying.

As the carrier film, a plastic film is used, for example, a polyester film such as polyethylene terephthalate (PET), a polyimide film, a polyamideimide film, a polypropylene film, a polystyrene film, etc. can be used. There is no particular restriction on the thickness of the carrier film, but it is generally selected appropriately in the range of 10 to 150 μm.

After forming a resin layer made of the curable resin composition of the present invention on the carrier film, it is preferable to further laminate a peelable cover film on the surface of the film for the purpose of preventing dust from adhering to the surface of the film. As the peelable cover film, for example, a polyethylene film, a polytetrafluoroethylene film, a polypropylene film, surface-treated paper, etc. can be used. The cover film may have a smaller adhesive force than that between the resin layer and the carrier film when the cover film is peeled off.

In the present invention, the curable resin composition of the present invention may be applied to the cover film and dried to form a resin layer, and a carrier film may be laminated on the surface of the resin layer. In other words, when producing a dry film in the present invention, either a carrier film or a cover film may be used as the film to which the curable resin composition of the present invention is applied.

[Cured product]
To form a cured product using the curable resin composition of the present invention, the composition is applied onto a substrate, the solvent is evaporated and dried, and then the resulting resin layer is exposed (irradiated with light) to cure the exposed portion (the portion irradiated with light). Specifically, the composition is selectively exposed to active energy rays through a photomask having a pattern formed thereon by a contact or non-contact method, or the pattern is directly exposed by a laser direct exposure machine, and the unexposed portion is developed with an alkaline aqueous solution (e.g., a 0.3 to 3 mass% aqueous solution of sodium carbonate), thereby forming a resist pattern. Furthermore, the composition is heated to a temperature of about 100 to 180°C for thermal curing (post-curing), thereby forming a cured coating film (cured product) having excellent properties such as heat resistance, chemical resistance, moisture absorption resistance, adhesion, and electrical properties.

The curable resin composition of the present invention can be adjusted to a viscosity suitable for the application method using the organic solvent, and applied to a substrate by a method such as dip coating, flow coating, roll coating, bar coating, screen printing, or curtain coating, and then the organic solvent contained in the composition can be evaporated and dried (pre-dried) at a temperature of about 60 to 100°C to form a tack-free resin layer. In addition, in the case of a dry film in which the curable resin composition is applied to a carrier film or cover film, dried, and wound up as a film, the resin layer can be transferred onto the substrate by laminating the film so that the resin layer is in contact with the substrate using a laminator or the like, and then peeling off the carrier film.

As for the substrate, in addition to printed wiring boards and flexible printed wiring boards with circuits formed in advance using copper or the like, 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, copper-clad laminates for high frequency circuits using fluororesin, polyethylene, polyphenylene ether, polyphenylene oxide, cyanate, etc. can be used. Examples include copper-clad laminates of all grades (FR-4, etc.), as well as metal substrates, polyimide films, PET films, polyethylene naphthalate (PEN) films, glass substrates, ceramic substrates, wafer plates, etc.

The volatilization drying or thermal curing can be carried out using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, etc. (a method in which hot air in the dryer is brought into countercurrent contact using a heat source that uses steam for air heating, or a method in which hot air is blown onto the support from a nozzle).

The exposure machine used for the above-mentioned active energy ray irradiation may be a machine 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 active energy rays in the range of 350 to 450 nm, and further, a direct imaging machine (for example, a laser direct imaging machine that draws an image directly with a laser based on CAD data from a computer) may also be used. The lamp light source or laser light source of the direct imaging machine may have a maximum wavelength in the range of 350 to 410 nm. The exposure dose for image formation varies depending on the film thickness, etc., but can generally be within the range of 20 to 1000 mJ/cm ² , preferably 20 to 800 mJ/cm ² .

The above-mentioned developing method can be a dipping method, a shower method, a spray method, a brush method, etc., and the developing solution can be an alkaline aqueous solution of potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, amines, etc.

The curable resin composition of the present invention is preferably used to form a surface protective film such as a solder resist on a printed wiring board. The curable resin composition of the present invention may also be used as an interlayer insulating layer in a multilayer printed wiring board.

[Electronic Components]
The present invention also provides an electronic component having a cured product obtained by curing the curable resin composition of the present invention. By using the curable resin composition of the present invention, an electronic component with high quality and reliability can be provided.
In the present invention, electronic components refer to components used in electronic circuits, and include active components such as printed wiring boards, transistors, light-emitting diodes, and laser diodes, as well as passive components such as resistors, capacitors, inductors, and connectors, and the cured product of the present invention exerts the effects of the present invention as an insulating cured coating film for these components.

[Production of the curable resin composition of the present invention]
The curable resin composition of the present invention can be prepared by mixing and dispersing predetermined amounts of (A) a compound having an isocyanurate structure and two or more (meth)acryloyl groups, (B) an epoxy resin having an isocyanurate structure, and (C) a photopolymerization initiator, as well as other components as desired, using, for example, a three-roll mill or the like.

The following examples illustrate one aspect of the present invention, but are not intended to limit the scope of the invention claimed in the present application.

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples. However, it goes without saying that the present invention is not limited to the following examples.
Unless otherwise specified, all parts and percentages are by weight.

[Examples 1 to 7 and Comparative Examples 1 to 3]
The components shown in Table 1 below were premixed in the respective amounts in a stirrer, and then kneaded in a three-roll mill to prepare curable resin compositions of Examples 1 to 7 and Comparative Examples 1 to 3. The stirring conditions of the stirrer were a premixing speed of 500 rpm and a stirring time of 10 min, and a main stirring speed of 800 rpm and a stirring time of 15 min. The stirrer blade used for each stirring was 12 cm. The values in the table are the values of solids excluding the organic solvent.

(Synthesis Example 1)
A 2-liter separable flask equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel and a nitrogen inlet tube was charged with 900 g of diethylene glycol dimethyl ether as a solvent and 21.4 g of t-butylperoxy 2-ethylhexanoate (Perbutyl O, manufactured by Nippon Oil & Fats Co., Ltd.) as a polymerization initiator, and heated to 90° C. After heating, 309.9 g of methacrylic acid, 116.4 g of methyl methacrylate, and 109.8 g of lactone-modified 2-hydroxyethyl methacrylate (Placcel FM1, manufactured by Daicel Chemical Industries, Ltd.) were added dropwise over 3 hours together with 21.4 g of bis(4-t-butylcyclohexyl)peroxydicarbonate (Perloyl TCP, manufactured by Nippon Oil & Fats Co., Ltd.) as a polymerization initiator, and the mixture was further aged for 6 hours to obtain a carboxyl group-containing copolymer resin. The reaction was carried out under a nitrogen atmosphere.
Next, 363.9 g of 3,4-epoxycyclohexylmethyl acrylate (Cyclomer A200, manufactured by Daicel Chemical Industries, Ltd.), 3.6 g of dimethylbenzylamine as a ring-opening catalyst, and 1.80 g of hydroquinone monomethyl ether as a polymerization inhibitor were added to the obtained carboxyl group-containing copolymer resin, and the mixture was heated to 100° C. and stirred to carry out a ring-opening addition reaction of epoxy. After 16 hours, a solution containing a carboxyl group-containing resin having no aromatic ring and having an acid value of 108.9 mgKOH/g and a weight average molecular weight of 25,000 in the solid content was obtained.

^＊１ Ａ－９３００ＹＮ；エトキシ化イソシアヌル酸トリアクリレート、新中村化学社製
^＊２ Ａ－ＤＯＤ－Ｎ；１，１０－デカンジオールジアクリレート、新中村化学社製
^＊３ Ａ－ＤＰＨ；新中村化学社製
^＊４ Ｌａｒｏｍｅｒ ＬＲ８８６３；ＢＡＳＦ社製
^＊５ ＴＥＰＩＣ（登録商標）－ＶＬ；日産化学社製
^＊６ ｊＥＲ８２８；三菱ケミカル社製
^＊７ 合成例１
^＊８ ＴＩＦ－３（酸価１３０ｍｇＫＯＨ／ｇ）；新中村化学社製
^＊９ Ｏｍｎｉｒａｄ ＴＰＯ；２，４，６－トリメチルベンゾイル－ジフェニルフォスフィンオキサイド；ＩＧＭ Ｒｅｓｉｎｓ社製
^＊１０ Ｏｍｎｉｒａｄ８１９；ビス（２，４，６－トリメチルベンゾイル）フェニルフォスフィンオキサイド；ＩＧＭ Ｒｅｓｉｎｓ社製
^＊１１ Ｉｒｇａｎｏｘ３１１４；ＢＡＳＦジャパン社製
^＊１２ Ｉｒｇａｎｏｘ１０１０；ＢＡＳＦジャパン社製
^＊１３ Ｉｒｇａｎｏｘ１３３０；ＢＡＳＦジャパン社製
^＊１４ ＰＸ－３７８８；堺化学工業（株）社製
^＊１５ Ｎｉｐｓｉｌ Ｅ－７４３（平均粒径１．５～２．２μｍ；比表面積：４５ｍ^２／ｇ）；東ソー・シリカ社製
^＊１６ AEROSIL R９７４（一次粒径１２ｎｍ；比表面積：１５０～１９０ｍ^２／ｇ）；日本アエロジル社製

^*1 A-9300YN: Ethoxylated isocyanuric acid triacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.
^*2 A-DOD-N: 1,10-decanediol diacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.
^*3 A-DPH; manufactured by Shin-Nakamura Chemical Co., Ltd.
^*4 Laromer LR8863; manufactured by BASF
^*5 TEPIC (registered trademark)-VL; manufactured by Nissan Chemical Industries, Ltd.
^*6 jER828; manufactured by Mitsubishi Chemical Corporation
^*7 Synthesis Example 1
^*8 TIF-3 (acid value 130 mg KOH / g); manufactured by Shin-Nakamura Chemical Co., Ltd.
^*9 Omnirad TPO; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; manufactured by IGM Resins
^*10 Omnirad 819; bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide; manufactured by IGM Resins
^*11 Irganox 3114; manufactured by BASF Japan
^*12 Irganox 1010; manufactured by BASF Japan
^*13 Irganox 1330; manufactured by BASF Japan
^*14 PX-3788; manufactured by Sakai Chemical Industry Co., Ltd.
^*15 Nipsil E-743 (average particle size: 1.5 to 2.2 μm; specific surface area: 45 m ² /g); manufactured by Tosoh Silica Corporation
^*16 AEROSIL R974 (primary particle size 12 nm; specific surface area: 150-190 m ² /g); manufactured by Nippon Aerosil Co., Ltd.

The obtained curable resin compositions of Examples 1 to 7 and Comparative Examples 1 to 3 were tested for color difference ΔE and storage stability as follows.

[Test for color difference ΔE (thermal discoloration resistance)]
The curable resin compositions of Examples 1 to 7 and Comparative Example 3 prepared above were applied to a glass substrate using an applicator, and dried at 80°C for 30 minutes to obtain a dried coating film with a thickness of 20 μm. After that, the substrate was irradiated with an exposure dose of 600 mJ/ ^cm2 using a metal halide lamp light source through a patterned negative, and then developed by immersion in a 1% by mass aqueous sodium carbonate solution, and then heated at 150°C for 60 minutes to perform a curing treatment.
The obtained substrate was subjected to a heat treatment once for 10 seconds at a peak top temperature of 285° C. The amount of change in color ΔE (color difference) from the initial value was calculated.
Those in which ΔE was 2.0 or less were rated as ⊚, those in which ΔE was 2.1 or more and less than 4.0 were rated as ◯, and those in which ΔE was 4.0 or more were rated as x.

[Storage stability test]
Each of the curable resin compositions of Examples 1 to 7 and Comparative Examples 1 to 3 was allowed to stand at 20° C., and the number of days from the time of standing until separation occurred on the surface of the curable resin composition was recorded.

Claims (8)

At least the following components (A) to (C):
(A) a compound having an isocyanurate structure and two or more (meth)acryloyl groups,
(B) an epoxy resin having an isocyanurate structure, and (C) a photopolymerization initiator .
and a curable resin composition containing a carboxyl group-containing fluororesin . The curable resin composition according to claim 1, further comprising (D) an antioxidant having an isocyanurate structure. The curable resin composition according to claim 1 or 2, further comprising (E) a white colorant. The curable resin composition according to any one of claims 1 to 3, further comprising a carboxyl group-containing resin that does not contain a fluorine atom. The curable resin composition according to any one of claims 1 to 4, further comprising at least one of silica having a specific surface area of 10 m ² /g or more and less than 100 ^{m 2 /} g and silica having a specific surface area of 100 m ^{2 /g or more and less than 300 m 2} /g. A dry film having a resin layer made of the curable resin composition according to any one of claims 1 to 5. A curable resin composition according to any one of claims 1 to 5, or a cured product of the resin layer of the dry film according to claim 6. An electronic component having the cured product according to claim 7.