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

Abstract

The present invention provides a thermosetting resin composition, dry film, cured product, and electronic component having high reflectivity and excellent discoloration resistance, heat resistance, acid resistance, and flexibility. The thermosetting resin composition comprises: (A) a hydroxyl and carboxyl group-containing resin starting from a phenoxy resin; (B) a blocked isocyanate compound; (C) an epoxy resin; and (D) titanium oxide.

Description

Technical Field

[0001] The present invention relates to a thermosetting resin composition having high reflectivity and excellent discoloration resistance, heat resistance, acid resistance, and flexibility, and also relates to a dry film and an electronic device using the thermosetting resin composition. Background Art

[0002] In recent years, printed circuit boards (PCBs) have seen an increasing use of low-power LEDs, such as backlights for liquid crystal displays (LCDs) in portable terminals, personal computers, and televisions, and as light sources for lighting fixtures. Insulating films, used as protective films on PCBs, are required to exhibit excellent light reflectivity, discoloration resistance, and heat resistance, as well as flexibility suitable for flexible printed circuit boards such as polyimide. Furthermore, acidic solutions such as sulfuric acid are used to clean the PCB surface during pre-plating processes, necessitating acid resistance for the insulating films.

[0003] Prior art has proposed curing systems comprising epoxy resins and imidazoles, acid anhydrides and epoxy resins, styrene-maleic anhydride copolymers and polyfunctional alicyclic epoxy resins, and polyester resins and isocyanate compounds (see Patent Documents 1-3). However, these compositions suffer from insufficient flexibility, reflectivity, discoloration resistance, and acid resistance in the cured products.

[0004] Furthermore, Patent Document 4 below discloses a photosensitive composition comprising a carboxyl group-containing resin having an aromatic ring, titanium oxide, a compound having a cyclic ether skeleton, and a photopolymerization initiator. However, the composition is insufficient in flexibility and discoloration resistance.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2005-36218

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2010-229221

[0009] Patent Document 3: China Patent Publication No. 108227378

[0010] Patent Document 4: Japanese Patent Application Laid-Open No. 2012-108523 Summary of the Invention

[0011] Problems to be solved by the invention

[0012] As previously mentioned, existing curable resin compositions have failed to produce cured films with high reflectivity and excellent discoloration resistance, heat resistance, acid resistance, and flexibility. The present invention was developed to address this problem, and its object is to provide a thermosetting resin composition, a dry film, a cured product thereof, and an electronic component using the same, capable of producing a cured product with high reflectivity and excellent discoloration resistance, heat resistance, acid resistance, and flexibility.

[0013] Solutions for solving problems

[0014] The present inventors conducted intensive research and found that the above-mentioned problems can be solved by implementing the following invention.

[0015] The present invention is as follows:

[0016] Item 1

[0017] A thermosetting resin composition, characterized in that it contains:

[0018] (A) a resin containing hydroxyl groups and carboxyl groups using a phenoxy resin as a starting material,

[0019] (B) blocked isocyanate compounds,

[0020] (C) epoxy resin, and

[0021] (D) Titanium oxide.

[0022] Item 2

[0023] The thermosetting resin composition according to item 1, wherein the dissociation temperature of the blocking agent of the (B) blocked isocyanate compound is 100° C. or higher and 130° C. or lower.

[0024] Item 3

[0025] The thermosetting resin composition according to item 1 or 2, wherein the (B) blocked isocyanate compound comprises a trimer.

[0026] Item 4

[0027] The thermosetting resin composition according to item 1 or 2, wherein the (A) resin containing hydroxyl groups and carboxyl groups starting from a phenoxy resin is a resin containing hydroxyl groups and carboxyl groups starting from a bisphenol A type phenoxy resin.

[0028] Item 5

[0029] The thermosetting resin composition according to item 1 or 2, wherein the amount of the blocked isocyanate compound (B) is 5 to 200 parts by mass per 100 parts by mass of the resin (A) containing hydroxyl groups and carboxyl groups starting from a phenoxy resin.

[0030] Item 6

[0031] The thermosetting resin composition according to item 1 or 2, wherein the amount of the epoxy resin (C) is 5 to 200 parts by mass per 100 parts by mass of the resin (A) containing hydroxyl groups and carboxyl groups starting from a phenoxy resin.

[0032] Item 7

[0033] The thermosetting resin composition according to item 1 or 2, wherein the amount of the titanium oxide (D) is 60 to 400 parts by mass per 100 parts by mass of the resin (A) containing hydroxyl groups and carboxyl groups starting from a phenoxy resin.

[0034] Item 8

[0035] A dry film characterized by comprising a resin layer obtained from the thermosetting resin composition according to any one of items 1 to 7.

[0036] Item 9

[0037] A cured product characterized by being obtained by curing the thermosetting resin composition according to any one of items 1 to 7 or the resin layer of the dry film according to item 8.

[0038] Item 10

[0039] An electronic component comprising the cured product according to item 9.

[0040] Effects of the Invention

[0041] According to the present invention, a thermosetting resin composition, a dry film, a cured product thereof, and an electronic device using the same can be provided, which can provide a cured product having high reflectivity and excellent discoloration resistance, heat resistance, acid resistance, and flexibility. DETAILED DESCRIPTION

[0042] The present invention will be described in detail below. The following description of the technical contents is based on representative embodiments and specific examples of the present invention, and the present invention is not limited to these embodiments and specific examples. In addition, the following description is made:

[0043] In this specification, the numerical range represented by "a numerical value A to a numerical value B" includes the numerical values ​​A and B at the endpoints.

[0044] In this specification, "%" means weight or mass percentage unless otherwise specified.

[0045] In this specification, "may" means that the processing may or may not be performed.

[0046] In this specification, "optionally" or "optionally" means that a substance, component, process, condition, etc. is used or not used.

[0047] In this manual, the names of units are all names of international standard units.

[0048] In this specification, "a plurality of" means two or more unless otherwise specified.

[0049] Throughout this specification, terms such as "some (preferred) embodiments," "other (preferred) embodiments," and "embodiments" indicate that specific elements (e.g., features, structures, properties, and / or characteristics) associated with the embodiments are included in at least one embodiment described herein and may be present or absent in other embodiments. Furthermore, the aforementioned elements may be combined in any appropriate manner in various embodiments.

[0050] The thermosetting resin composition of the present invention is characterized by containing:

[0051] (A) a resin containing hydroxyl groups and carboxyl groups using a phenoxy resin as a starting material,

[0052] (B) blocked isocyanate compounds,

[0053] (C) epoxy resin, and

[0054] (D) Titanium oxide.

[0055] By using the components (A) to (C) in combination with a thermosetting resin composition containing titanium oxide, a cured product having high reflectivity and discoloration resistance as well as excellent heat resistance, acid resistance, and flexibility can be obtained.

[0056] That is, it is believed that the above-mentioned effect can be achieved by using the (B) blocked isocyanate compound and the (C) epoxy resin in combination as thermosetting components and containing the (A) resin derived from a phenoxy resin and having hydroxyl groups and carboxyl groups that undergo thermosetting reactions with the (B) and (C) components.

[0057] Hereinafter, each component of the thermosetting resin composition of the present invention will be described.

[0058] <(A) Resin containing hydroxyl groups and carboxyl groups starting from a phenoxy resin>

[0059] The (A) hydroxyl- and carboxyl-containing resin starting from a phenoxy resin contained in the thermosetting resin composition of the present invention is not particularly limited in molecular structure or synthesis method as long as it is a hydroxyl- and carboxyl-containing resin synthesized from a phenoxy resin.

[0060] It should be noted that component (A) used in the present invention is different from the hydroxyl and / or carboxyl group-containing resins commonly used in printed circuit boards, which are based on epoxy resins as starting materials. Furthermore, it may or may not contain epoxy groups. For example, epoxy groups may be introduced depending on the raw materials, the synthesis process, etc.

[0061] The phenoxy resin as the starting material of the component (A) can be obtained, for example, by a condensation reaction of a diphenol compound and an epihalohydrin, or an addition polymerization reaction of a diphenol compound and a bifunctional epoxy resin, and can be obtained by conventionally known methods in solution or without a solvent.

[0062] Examples of the divalent phenol compound used to produce the phenoxy resin include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, 4,4-biphenol, 4,4'-dihydroxybenzophenone, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, Bis(4-hydroxyphenyl)diphenylmethane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(3-phenyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-tert-butylphenyl)propane, 1,3-bis(2-(4-hydroxyphenyl)propyl)benzene, 1,4-bis(2-(4-hydroxyphenyl)propyl)benzene, 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, 9,9'-bis(4-hydroxyphenyl)fluorene, etc. Among them, bisphenol A, bisphenol F, 4,4-biphenyldiphenol, 4,4'-dihydroxybenzophenone, or 9,9'-bis(4-hydroxyphenyl)fluorene is particularly preferred from the perspectives of physical properties, cost, and availability.

[0063] Furthermore, from the viewpoint of improving discoloration resistance, heat resistance, acid resistance, and flexibility, bisphenol A and bisphenol F are preferred, and bisphenol A is more preferred.

[0064] That is, the phenoxy resin as the starting material of the component (A) is preferably a bisphenol-type phenoxy resin such as bisphenol A-type phenoxy resin, bisphenol F-type phenoxy resin, a copolymerized phenoxy resin of bisphenol A and bisphenol F, or a modified product thereof, and more preferably a bisphenol A-type phenoxy resin.

[0065] The mass average molecular weight (Mw) of the phenoxy resin is typically 10,000 to 200,000. It is preferably 25,000 to 100,000, and more preferably 30,000 to 70,000. Within this range, the strength and discoloration resistance of the cured product are maintained while also balancing the handleability, processability, and flexibility of the cured product. Mw represents the value measured by gel permeation chromatography and converted using a standard polystyrene calibration curve.

[0066] The hydroxyl equivalent (g / eq) of the phenoxy resin is generally 55 to 1,200, preferably 120 to 800, and particularly preferably 220 to 450. Within this range, water absorption by the hydroxyl groups of the cured product is suppressed, and sufficient curing is easily achieved.

[0067] In the present invention, (A) the resin containing hydroxyl groups and carboxyl groups using a phenoxy resin as a starting material may be a product obtained by modifying the phenoxy resin as a starting material into carboxyl groups while retaining a part of the hydroxyl groups.

[0068] Specifically, component (A) can be obtained by, for example, reacting a portion of the hydroxyl groups of the phenoxy resin with a compound M having a carboxyl group or a precursor of a carboxyl group that reacts with the hydroxyl groups of the phenoxy resin, and converting the precursor into a carboxyl group as needed.

[0069] As the compound M, for example, an acid anhydride is preferred. Examples of the acid anhydride include phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, pyromellitic anhydride, trimellitic anhydride, methylnadic anhydride, 1,3,3a,4,5,9b-hexahydro-5 (tetrahydro-2,5-dioxo-3-furyl) naphtho[1,2-c]furan-1,3-dione, 1,2,3,4-butanetetracarboxylic dianhydride, hydrogenated pyromellitic anhydride, and hydrogenated trimellitic anhydride. From the perspective of reactivity, phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, pyromellitic anhydride, and trimellitic anhydride are preferred, and tetrahydrophthalic anhydride and trimellitic anhydride are more preferred.

[0070] In addition, from the viewpoint of obtaining better whiteness and reflectivity, it is preferable to use aliphatic anhydrides such as tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and hexahydrophthalic anhydride.

[0071] In the resin (A) containing hydroxyl groups and carboxyl groups, which is prepared from a phenoxy resin as a starting material and is used in the present invention, the ratio of the hydroxyl groups to the carboxyl groups is not particularly limited. Generally, the number of carboxyl groups is in the range of 10% to 90% relative to the total number of hydroxyl groups and carboxyl groups. From the perspective of obtaining a cured product having superior discoloration resistance, heat resistance, acid resistance, and flexibility, the ratio is preferably in the range of 20% to 80%, more preferably 30% to 70%, and even more preferably 40% to 60%.

[0072] <(B) Blocked isocyanate compound>

[0073] The blocked isocyanate compound (B) contained in the thermosetting resin composition of the present invention is a compound obtained by masking the isocyanate group of the isocyanate compound with a blocking agent to suppress its reactivity. When the thermosetting resin composition of the present invention is used, the blocked isocyanate compound (B) is subjected to appropriate treatment (e.g., heat treatment) to dissociate the blocking agent and regenerate the isocyanate group. The blocked isocyanate compound (B) may be contained in the thermosetting resin composition of the present invention as a single species or as a mixture of two or more species.

[0074] As the isocyanate compound in the (B) blocked isocyanate compound, for example, aromatic isocyanate, aliphatic isocyanate, or alicyclic isocyanate is used.

[0075] Specific examples of the aromatic isocyanate include 4,4′-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, naphthalene-1,5-diisocyanate, o-xylylene diisocyanate, m-xylylene diisocyanate, triphenylmethane triisocyanate, and polymethylene polyphenyl polyisocyanate.

[0076] Specific examples of the aliphatic isocyanate include tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, and trimethylhexamethylene diisocyanate.

[0077] Specific examples of the alicyclic isocyanate include 4,4-methylenebis(cyclohexyl isocyanate), isophorone diisocyanate, and dicycloheptane triisocyanate.

[0078] It should be noted that these isocyanates can be used in the form of multimers such as dimers and trimers. Representative multimers include uretdione and biuret forms, which are dimers, and isocyanurate forms, which are trimers, but are not limited to these.

[0079] Among these, when a trimer is used as the blocked isocyanate compound (B), the effect of improving discoloration resistance and soldering heat resistance is particularly significant. In other words, from the perspective of excellent discoloration resistance and soldering heat resistance, a blocked isocyanate containing a trimer, i.e., a blocked isocyanate having an isocyanurate structure, is preferred.

[0080] The dissociation temperature of the blocking agent of the blocked isocyanate compound (B) is not particularly limited, but is generally 80°C to 150°C. To obtain a cured product having high reflectivity, resistance to discoloration, excellent heat resistance, acid resistance, and flexibility, and excellent storage stability of the composition at room temperature, the dissociation temperature is preferably 90°C to 140°C, and more preferably 100°C to 130°C.

[0081] (B) The blocked isocyanate compound may be a commercially available product, and examples thereof include Trixene BI 7982 (manufactured by Baxenden), Duranate TKA-B75S, TPA-B80E, 17B-60PX, and E402-B80T (trade names of Asahi Kasei Corporation).

[0082] Among them, from the perspective of increasing the effect of improving discoloration resistance and soldering heat resistance, in other words, from the perspective of being particularly excellent in discoloration resistance and soldering heat resistance, Trixene BI 7982 (manufactured by BAXENDEN) and Duranate TKA-B75S (manufactured by Asahi Kasei Corporation) having an isocyanurate structure and a dissociation temperature within the above-mentioned preferred range are preferred.

[0083] The amount of the blocked isocyanate compound (B) to be added is not particularly limited. However, from the perspective of achieving high levels of both flexibility and soldering heat resistance of the cured film, the amount of the blocked isocyanate compound (B) to be added is preferably 5 to 200 parts by mass, more preferably 8 to 100 parts by mass, and even more preferably 10 to 50 parts by mass, relative to 100 parts by mass of the resin (A) containing hydroxyl groups and carboxyl groups, which is prepared using a phenoxy resin as a starting material.

[0084] <(C) Epoxy resin>

[0085] The epoxy resin (C) used in the present invention is a resin having an epoxy group, and any known product can be used, including a bifunctional epoxy resin having two epoxy groups in the molecule and a polyfunctional epoxy resin having three or more epoxy groups in the molecule.

[0086] Examples of the epoxy resin (C) include bisphenol A epoxy resins, brominated epoxy resins, novolac epoxy resins, bisphenol F epoxy resins, hydrogenated bisphenol A epoxy resins, glycidylamine epoxy resins, hydantoin epoxy resins, alicyclic epoxy resins, trishydroxyphenylmethane epoxy resins, biphenylene or biphenol epoxy resins, or mixtures thereof; bisphenol S epoxy resins, bisphenol A novolac epoxy resins, tetraphenolethane epoxy resins, heterocyclic epoxy resins, diglycidyl phthalate resins, tetraglycidylxylenoylethane resins, naphthyl-containing epoxy resins, and epoxy resins having a dicyclopentadiene skeleton.

[0087] Among them, from the perspective of improving the curability of the composition and the flexibility of the cured film, bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl novolac type epoxy resin, bisxylenol type epoxy resin, phenol novolac type epoxy resin or modified products thereof are preferred. In particular, from the perspective of improving soldering heat resistance, phenol novolac type epoxy resin is more preferred.

[0088] Among epoxy resins, epoxy resins having an alicyclic skeleton and not containing a benzene ring skeleton are preferred from the viewpoint of flexibility.

[0089] (C) The epoxy resin may be a commercially available product, and examples thereof include bisphenol A-type epoxy resins such as jER828, jER834, jER1001, and jER1004 manufactured by Mitsubishi Chemical Corporation; EPICLON840, EPICLON850, EPICLON1050, and EPICLON2055 manufactured by DIC Corporation; and Epototo YD-011, YD-013, YD-127, and YD-128 (all trade names) manufactured by NIPPON STEEL Chemical & Material Co., Ltd.; jER YL903 manufactured by Mitsubishi Chemical Corporation; EPICLON152 and EPICLON165 manufactured by DIC Corporation; and EPICLON 166 manufactured by NIPPON STEEL Chemical & Material Co., Ltd. Brominated epoxy resins such as Epototo YDB-400 and YDB-500 (all trade names) manufactured by Co., Ltd.; jER152 and jER154 manufactured by Mitsubishi Chemical Corporation; EPICLON N-730, EPICLON N-770 and EPICLON N-865 manufactured by DIC Corporation; Epototo YDCN-701 and YDCN-704 manufactured by NIPPON STEEL Chemical & Material Co., Ltd.; EPPN-201, EOCN-1025, EOCN-1020, EOCN-104S and RE-306 (all trade names) manufactured by Nippon Kayaku Co., Ltd.; EPICLON 830 manufactured by DIC Corporation; jER807 manufactured by Mitsubishi Chemical Corporation; Bisphenol F epoxy resins such as Epototo YDF-170, YDF-175, and YDF-2004 (all trade names) manufactured by Chemical & Material Co., Ltd.; hydrogenated bisphenol A epoxy resins such as Epototo ST-2004, ST-2007, and ST-3000 (all trade names) manufactured by NIPPON STEEL Chemical & Material Co., Ltd.; jER604 manufactured by Mitsubishi Chemical Corporation and NIPPON STEEL Chemical & Material Co., Ltd.Glycidylamine type epoxy resins such as Epototo YH-434 manufactured by Sumitomo Chemical Co., Ltd. and Sumi-Epoxy ELM-120 manufactured by Sumitomo Chemical Co., Ltd. (both trade names); alicyclic epoxy resins such as Celloxide 2021 manufactured by Daicel Corporation (trade name); trishydroxyphenylmethane type epoxy resins such as YL-933 manufactured by Mitsubishi Chemical Corporation and EPPN-501 and EPPN-502 manufactured by Nippon Kayaku Co., Ltd. (both trade names); YL-60 manufactured by Mitsubishi Chemical Corporation. 56. Bisphenol-type or biphenol-type epoxy resins such as YX-4000 and YL-6121 (both trade names) or mixtures thereof; bisphenol S-type epoxy resins such as EBPS-200 manufactured by Nippon Kayaku Co., Ltd., EPX-30 manufactured by ADEKA Co., Ltd., and EXA-1514 manufactured by DIC Co., Ltd. (all trade names); bisphenol A novolac-type epoxy resins such as jER157S (trade name) manufactured by Mitsubishi Chemical Corporation; jER Tetrakisphenol ethane type epoxy resins such as YL-931 (trade name); heterocyclic epoxy resins such as TEPIC (trade name) manufactured by Nissan Chemical Co., Ltd.; diglycidyl phthalate resins such as Blemmer DGT (trade name) manufactured by NOF Corporation; tetraglycidyl ditoluoyl ethane resins such as ZX-1063 (trade name) manufactured by NIPPON STEEL Chemical & Material Co., Ltd.; NIPPON STEEL Chemical & Material Co., Ltd., such as ESN-190 and ESN-360; DIC Corporation's HP-4032, EXA-4750, and EXA-4700 (all trade names); DIC Corporation's HP-7200 and HP-7200H (all trade names) and other epoxy resins having a dicyclopentadiene skeleton; NOF Corporation's CP-50S and CP-50M (all trade names) and other glycidyl methacrylate copolymer-based epoxy resins; and cyclohexylmaleimide and glycidyl methacrylate copolymerized epoxy resins. These epoxy compounds can be used alone or in combination of two or more.

[0090] The amount of the epoxy resin (C) is preferably 5 to 200 parts by mass, more preferably 10 to 100 parts by mass, and even more preferably 15 to 50 parts by mass, relative to 100 parts by mass of the resin (A) containing hydroxyl and carboxyl groups, which is derived from a phenoxy resin as a starting material. Within this range, the viscosity of the composition is within an appropriate range, achieving a balance between coatability and coating film strength, and readily yielding a cured product with excellent discoloration resistance and flexibility. The epoxy resin (C) may be contained in the thermosetting resin composition of the present invention alone or as a mixture of two or more.

[0091] <(D) Titanium oxide>

[0092] As the titanium oxide (D) that can be used in the thermosetting resin composition of the present invention, titanium oxide produced by a sulfuric acid process or a chlorine process, rutile titanium oxide, anatase titanium oxide, or titanium oxide that has been surface-treated with a hydrated metal oxide or a surface-treated with an organic compound can be used. Titanium oxide is classified into rutile and anatase types according to its crystal structure. Among them, rutile titanium oxide is preferred. Anatase titanium oxide has a higher whiteness than rutile type and is therefore often used. However, anatase titanium oxide has photocatalytic activity and therefore sometimes causes discoloration of the resin. In contrast, although rutile titanium oxide has a slightly lower whiteness than anatase type, it has almost no photoactivity and therefore can obtain a stable cured film.

[0093] As rutile titanium oxide, known rutile titanium oxide can be used. Specifically, TR-600, TR-700, TR-750, TR-840 manufactured by Fuji Titanium Industry Co., Ltd., R-550, R-580, R-630, R-820, CR-50, CR-58, CR-60, CR-90, CR-97 manufactured by Ishihara Industry Co., Ltd., KR-270, KR-310, KR-380 manufactured by Titanium Industry Co., Ltd., etc. can be used. Among these rutile titanium oxides, titanium oxide whose surface is treated with hydrated aluminum oxide or aluminum hydroxide is particularly preferably used from the viewpoints of dispersibility in the composition, storage stability, and flame retardancy.

[0094] The amount of titanium oxide (D) is, for example, 60 to 400 parts by mass, preferably 80 to 300 parts by mass, and more preferably 100 to 200 parts by mass, relative to 100 parts by mass of the resin (A) containing hydroxyl and carboxyl groups, which is derived from a phenoxy resin as a starting material. Amounts of 400 parts by mass or less facilitate dispersion, while no further improvement in reflectivity is observed even when the amount exceeds 400 parts by mass. Furthermore, a reflectivity-enhancing effect of titanium oxide (D) is enhanced when the amount is 60 parts by mass or greater.

[0095] <Other ingredients>

[0096] When high reflectivity is required for a substrate for mounting a light-emitting element, the thermosetting resin composition of the present invention may contain a color pigment with high reflectivity at the emission wavelength. In particular, when visible light is used, the composition may contain a white pigment (D) other than titanium oxide. Preferred examples of such white pigments include zinc oxide, aluminum oxide, and zirconium oxide.

[0097] The thermosetting resin composition of the present invention may further contain other thermosetting components in addition to the above-mentioned components (A) to (C). Other thermosetting components include amine resins such as episulfide resins, melamine resins, melamine derivatives, benzoguanamine resins, benzoguanamine derivatives, cyclocarbonate compounds, bismaleimides, oxazine compounds, oxazoline compounds, carbodiimide resins, and other commonly known thermosetting resins. For example, there are methylol melamine compounds, methylol benzoguanamine compounds, methylol glycoluril compounds, and methylol urea compounds. Furthermore, alkoxymethylated melamine compounds, alkoxymethylated benzoguanamine compounds, alkoxymethylated glycoluril compounds, and alkoxymethylated urea compounds can be obtained by converting the methylol groups of methylol melamine compounds, methylol benzoguanamine compounds, methylol glycoluril compounds, and methylol urea compounds into alkoxymethyl groups. The type of alkoxymethyl group is not particularly limited, and for example, methoxymethyl, ethoxymethyl, propoxymethyl, butoxymethyl, and the like can be used. In particular, melamine derivatives having a formalin concentration of 0.2% or less, which are friendly to the human body and the environment, are preferred.

[0098] These other thermosetting components can be used alone or in combination of two or more.

[0099] The thermosetting resin composition of the present invention may further contain a thermosetting catalyst. Examples of such thermosetting catalysts include imidazole derivatives such as imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole; amine compounds such as dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethylbenzylamine, 4-methoxy-N,N-dimethylbenzylamine, and 4-methyl-N,N-dimethylbenzylamine; hydrazine compounds such as adipic acid dihydrazide and sebacic acid dihydrazide; and phosphorus compounds such as triphenylphosphine. Commercially available products include 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, and 2P4MHZ (all trade names of imidazole compounds) manufactured by Shikoku Chemicals Co., Ltd.; and SAN-APRO LTD. U-CAT (registered trademark) 3503N, U-CAT3502T (all are trade names of blocked isocyanate compounds of dimethylamine), DBU, DBN, U-CATSA102, U-CAT5002 (all are bicyclic amidine compounds and their salts) and the like. They are not particularly limited thereto and can be used alone or in combination with two or more thereof. In addition, guanamine, methylguanamine, benzoguanamine, melamine, 2,4-diamino-6-methacryloyloxyethyl-s-triazine, 2-vinyl-2,4-diamino-s-triazine, 2-vinyl-4,6-diamino-s-triazine-isocyanuric acid adduct, s-triazine derivatives such as 2,4-diamino-6-methacryloyloxyethyl-s-triazine-isocyanuric acid adduct can also be used. It is preferred that these compounds which also function as adhesion imparting agents are used in combination with the aforementioned thermosetting catalyst.

[0100] The amount of these thermosetting catalysts to be added may be a normal ratio, for example, preferably 0.1 to 20 parts by mass, more preferably 0.5 to 15.0 parts by mass, relative to 100 parts by mass of the resin (A) containing hydroxyl groups and carboxyl groups starting from a phenoxy resin.

[0101] The thermal curing catalysts may be used alone or in combination of two or more.

[0102] The thermosetting resin composition of the present invention may contain an antioxidant for the purpose of reducing degradation caused by heat applied to the coating film and / or discoloration caused by oxidative degradation. Examples of antioxidants include (1) free radical scavengers that neutralize generated free radicals and / or (2) peroxide decomposers that decompose generated peroxides into harmless substances without generating new free radicals.

[0103] Specific examples of antioxidants that function as free radical scavengers include hydroquinone, 4-tert-butylcatechol, 2-tert-butylhydroquinone, hydroquinone monomethyl ether, 2,6-di-tert-butyl-p-cresol, 2,2-methylene-bis(4-methyl-6-tert-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, and 1,3,5-trimethyl-2-hydroxy-4-hydroxy-5-tert-butylphenylbutane. ,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,3,5-tris(3',5'-di-tert-butyl-4-hydroxybenzyl)-s-triazine-2,4,6-(1H,3H,5H)trione and other phenolic compounds, hydroquinone monomethyl ether (methoquinone), quinone compounds such as benzoquinone, bis(2,2,6,6-tetramethyl-4-piperidinyl)-sebacate, phenothiazine and other amine compounds, etc.

[0104] The radical scavenger may be a commercially available product, and examples thereof include Adekastab AO-30, Adekastab AO-330, Adekastab AO-20, Adekastab LA-77, Adekastab LA-57, Adekastab LA-67, Adekastab LA-68, and Adekastab LA-87 (all manufactured by ADEKA Corporation, trade names), IRGANOX 1010, IRGANOX 1035, IRGANOX 1076, IRGANOX 1135, TINUVIN 111FDL, TINUVIN 123, TINUVIN 144, TINUVIN 152, TINUVIN 292, and TINUVIN 5100 (all manufactured by BASF Japan Ltd., trade names).

[0105] Specific examples of antioxidants that function as peroxide decomposers include phosphorus compounds such as triphenyl phosphite, and sulfur compounds such as pentaerythritol tetralaurylthiopropionate, dilauryl thiodipropionate, and distearyl 3,3'-thiodipropionate.

[0106] The peroxide decomposer may be a commercially available product, and examples thereof include Adekastab TPP (trade name, manufactured by ADEKA Corporation), Mark AO-412S (trade name, manufactured by ADEKA Corporation), and SUMILIZER TPS (trade name, manufactured by Sumitomo Chemical Co., Ltd.).

[0107] The amount of the antioxidant added is preferably 0.4 to 25 parts by mass, more preferably 0.8 to 15 parts by mass, per 100 parts by mass of the resin (A) containing hydroxyl and carboxyl groups, which is prepared from a phenoxy resin as a starting material. When the amount is 0.4 parts by mass or greater, the effect of preventing discoloration caused by thermal degradation of the coating film is enhanced, while when the amount is 25 parts by mass or less, heat resistance and storage stability are further improved.

[0108] The antioxidants may be used alone or in combination of two or more.

[0109] Furthermore, generally, polymer materials absorb ultraviolet rays and thereby decompose and degrade. Therefore, in order to improve the stability against ultraviolet rays, an ultraviolet absorber may be used in addition to the above-mentioned antioxidant in the thermosetting resin composition of the present invention.

[0110] Examples of ultraviolet absorbers include benzophenone derivatives, benzoate derivatives, benzotriazole derivatives, triazine derivatives, benzothiazole derivatives, cinnamate derivatives, anthranilate derivatives, and dibenzoylmethane derivatives. Specific examples of benzophenone derivatives include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, and 2,4-dihydroxybenzophenone. Specific examples of benzoate derivatives include 2-ethylhexyl salicylate, phenyl salicylate, p-tert-butylphenyl salicylate, 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate, and hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate. Specific examples of benzotriazole derivatives include 2-(2'-hydroxy-5'-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, and 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole. Specific examples of triazine derivatives include hydroxyphenyltriazine and bis-ethylhexyloxyphenol methoxyphenyl triazine.

[0111] The ultraviolet absorber may be a commercially available item, and examples thereof include TINUVIN PS, TINUVIN 99-2, TINUVIN 109, TINUVIN 384-2, TINUVIN 900, TINUVIN 928, TINUVIN 1130, TINUVIN 400, TINUVIN 405, TINUVIN 460, and TINUVIN 479 (all manufactured by BASF Japan Ltd., trade names).

[0112] The aforementioned ultraviolet absorbers can be used alone or in combination of two or more. By using them in combination with the aforementioned antioxidant, the molded article obtained from the thermosetting resin composition of the present invention can be stabilized. The ultraviolet absorbers are preferably added in an amount of 0.01 to 5 parts by mass per 100 parts by mass of the resin (A) containing hydroxyl groups and carboxyl groups, which is prepared from a phenoxy resin as a starting material.

[0113] The thermosetting resin composition of the present invention can further improve stability against ultraviolet rays by further containing a hindered amine-based light stabilizer.

[0114] Examples of hindered amine light stabilizers include TINUVIN 622LD and TINUVIN 144; CHIMASSORB 944LD and CHIMASSORB 119FL (all manufactured by BASF Japan Ltd.); MARK LA-57, LA-62, LA-67, LA-63 and LA-68 (all manufactured by ADEKA Corporation); and Sanol LS-770, LS-765, LS-292, LS-2626, LS-1114 and LS-744 (all manufactured by Sankyo Lifetech Co., Ltd.).

[0115] Such a light stabilizer is preferably added in an amount of 0.1 to 10 parts by mass based on 100 parts by mass of the resin (A) containing hydroxyl groups and carboxyl groups, which is prepared from a phenoxy resin as a starting material.

[0116] The light stabilizers may be used alone or in combination of two or more.

[0117] The thermosetting resin composition of the present invention may further contain a dispersant in order to improve the dispersibility and sedimentation properties of titanium oxide and a white pigment other than titanium oxide added as needed.Examples: ANTI-TERRA-U, ANTI-TERRA-U100, ANTI-TERRA-204, ANTI-TERRA-205, DISPERBYK-101, DISPE RBYK-102, DISPERBYK-103, DISPERBYK-106, DISPERBYK-108, DISPERBYK-109, DISPERBYK-110, DISPERB YK-111, DISPERBYK-112, DISPERBYK-116, DISPERBYK-130, DISPERBYK-140, DISPERBYK-142, DISPERBY K-145, DISPERBYK-161, DISPERBYK-162, DISPERBYK-163, DISPERBYK-164, DISPERBYK-166, DISPERBYK- 167, DISPERBYK-168, DISPERBYK-170, DISPERBYK-171, DISPERBYK-174, DISPERBYK-180, DISPERBYK-1 82, DISPERBYK-183, DISPERBYK-185, DISPERBYK-184, DISPERBYK-2000, DISPERBYK-2001, DISPERBYK-2 009, DISPERBYK-2020, DISPERBYK-2025, DISPERBYK-2050, DISPERBYK-2070, DISPERBYK-2096, DISPERBYK-2150, BYKP104, BYK-P104S, BYK-P105, BYK-9076, BYK-9077, BYK-220S (BYK Japan Co., Ltd.), DISPARON 2150, DISPARON 1210, DISPARON KS-860, DISPARON KS-873N, DISPARON7004, DISPARON 1830, DISPARON 1860, DISPARON 1850, DISPARON DA-400N, DISPARON PW-36, DISPARON DA-703-50 (manufactured by Kusumoto Chemical Co., Ltd.), FLOWLEN G-450, FLOWLEN-600, FLOWLEN G-820, FLOWLEN G-700, FLOWLEN DOPA-44, FLOWLEN DOPA-17 (manufactured by Kyoyosha Chemical Co., Ltd.).

[0118] To effectively achieve the above purpose, the content of the dispersant is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the total of titanium oxide and white pigments other than titanium oxide added as needed.

[0119] The above-mentioned dispersants may be used alone or in combination of two or more.

[0120] It should be noted that the thermosetting resin composition of the present invention may also be blended with a photopolymerizable monomer having two or more ethylenically unsaturated groups in the molecule to impart photocurability to the composition. The composition of the present invention, thus formulated as a photocurable / thermosetting resin composition, can be thermally cured after photocuring and patterning by alkali development to form a cured film having a desired pattern. On the other hand, when the thermosetting resin composition is used to form a protective film on a printed circuit board, it is preferably free of the aforementioned photopolymerizable monomer from the perspective of the flexibility and adhesion of the resulting cured product.

[0121] Furthermore, the thermosetting resin composition of the present invention may contain an organic solvent for the preparation of the composition and for adjusting the viscosity. Examples of such organic solvents include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, and petroleum-based solvents. More specifically, there are 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, and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, dipropylene glycol methyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, and propylene glycol butyl ether acetate; alcohols such as ethanol, propanol, ethylene glycol, and propylene glycol; aliphatic hydrocarbons such as octane and decane; petroleum solvents such as petroleum ether, naphtha, hydrogenated naphtha, and solvent naphtha, etc.

[0122] These organic solvents may be used alone or in combination of two or more.

[0123] The thermosetting resin composition of the present invention may further contain, as necessary, known and commonly used additives such as finely divided silica, organic bentonite, montmorillonite and the like, silicone-based, fluorine-based, polymer-based defoamers and / or leveling agents, imidazole-based, thiazole-based, triazole-based and other silane coupling agents, antioxidants, rust inhibitors and the like.

[0124] The thermosetting resin composition of the present invention may be in the form of a dry film including a carrier film (support) and a layer composed of the thermosetting resin composition formed on the carrier film.

[0125] To form a dry film, the thermosetting resin composition of the present invention is diluted with the aforementioned organic solvent to an appropriate viscosity. The composition is then applied to a carrier film at a uniform thickness using a notch wheel coater, knife coater, lip coater, bar coater, extrusion coater, reverse coater, transfer roll coater, gravure coater, spray coater, or the like. The composition is then dried, typically at a temperature of 50 to 130°C for 1 to 30 minutes, to form a resin layer serving as a dried coating. The resin layer is not particularly limited, but is generally selected within the range of 10 to 150 μm, preferably 20 to 60 μm, in terms of film thickness after drying.

[0126] As the carrier film, a plastic film is used, preferably a polyester film such as polyethylene terephthalate, a polyimide film, a polyamide-imide film, a polypropylene film, a polystyrene film, or the like. The thickness of the carrier film is not particularly limited, but is generally selected within the range of 10 to 150 μm.

[0127] In this case, after forming the resin layer on the carrier film, it is preferable to further laminate a removable cover film on the surface of the resin layer to prevent dust from adhering to the surface of the resin layer. Examples of the removable cover film include polyethylene film, polytetrafluoroethylene film, polypropylene film, and surface-treated paper. When peeling the cover film, the adhesion between the resin layer and the cover film should be smaller than the adhesion between the resin layer and the carrier film.

[0128] Another aspect of the present invention provides a cured product obtained from the thermosetting resin composition or a dry film thereof.

[0129] The thermosetting resin composition of the present invention is adjusted to a viscosity suitable for the coating method as needed, and is applied to a printed circuit board having a circuit formed thereon by a method such as screen printing, curtain coating, spray coating, or roller coating. It is then heat-cured, for example, at a temperature of 140 to 180° C., thereby obtaining a cured product having high reflectivity and excellent discoloration resistance, heat resistance, acid resistance, and flexibility, as a protective film for electronic components.

[0130] When using a dry film, for example, the dry film of the present invention is attached to a printed circuit board having a circuit formed thereon to laminate a resin layer, and then the resin layer is cured by heating in the same manner as above to produce an electronic component having a cured product.

[0131] The heating for heat curing after coating the thermosetting resin composition of the present invention can be carried out using a hot air circulation drying furnace, an IR furnace, a hot plate, a convection oven, etc. (a method using a device with a heat source of steam-based air heating method, a method of causing hot air in the dryer to contact by convection; and a method of blowing toward the support body using a nozzle).

[0132] Another aspect of the present invention provides an electronic component comprising the cured product. Such an electronic component is used, for example, in backlights of liquid crystal displays of portable terminals, personal computers, televisions, and the like, and in light-emitting elements such as LEDs.

[0133] Example

[0134] The present invention will be described in detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[0135] Synthesis example 1

[0136] 250 parts of phenoxy resin 1256B40 (bisphenol A type phenoxy resin (manufactured by Mitsubishi Chemical Corporation, secondary hydroxyl equivalent: 280 g / eq., MEK diluted product, 40% by mass) and 27 parts of tetrahydrophthalic anhydride (152.14 g / mol) were mixed and reacted at 80°C with a reflux tube for 24 hours to synthesize a resin (1) containing hydroxyl groups and carboxyl groups.

[0137] Synthesis example 2

[0138] 250 parts of phenoxy resin 1256B40 (bisphenol A type phenoxy resin (manufactured by Mitsubishi Chemical Corporation, secondary hydroxyl equivalent: 280 g / eq., MEK diluted product, 40% by mass) and 34 parts of trimellitic anhydride (192.13 g / mol) were mixed and reacted at 80°C with a reflux tube for 24 hours to synthesize a resin (2) containing hydroxyl groups and carboxyl groups.

[0139] Synthesis example 3

[0140] To 600 g of diethylene glycol monoethyl ether acetate were added 1070 g (5.0 mol of glycidyl groups (total number of aromatic rings)) of an o-cresol novolac-type epoxy resin (manufactured by DIC Corporation, EPICLON N-695, softening point 95°C, epoxy equivalent 214, average number of functional groups 7.6), 360 g (5.0 mol) of acrylic acid, and 1.5 g of hydroquinone. The mixture was stirred and heated to 100°C to dissolve uniformly.

[0141] Next, 4.3 g of triphenylphosphine was added, and the mixture was heated to 110°C and allowed to react for 2 hours. The temperature was then raised to 120°C and allowed to react for an additional 12 hours. To the resulting reaction solution were added 415 g of an aromatic hydrocarbon (Solvesso 150) and 456.0 g (3.0 mol) of tetrahydrophthalic anhydride. The mixture was reacted at 110°C for 4 hours and then cooled to obtain a photosensitive carboxyl-containing resin solution.

[0142] The resin solution thus obtained had a solid content of 65% and an acid value of the solid content of 89 mgKOH / g.

[0143] The resins synthesized in the above-mentioned synthesis examples were used as the component (A) and mixed according to the formulation shown in Table 1 to obtain the thermosetting resin composition of each example.

[0144] Table 1

[0145]

[0146] Remark:

[0147] ※1KAYARAD ZAR-1035: A resin containing hydroxyl and carboxyl groups, made from bisphenol A epoxy acrylate resin, manufactured by Nippon Kayaku Co., Ltd.

[0148] ※2Vylon2000: Polyester resin, manufactured by TOYOBO VYLON DEPT.

[0149] ※3BI7992: Trixene BI 7982, a blocked isocyanate obtained from hexamethylene diisocyanate, a blocked isocyanate with an isocyanurate structure, including trimers, dissociates at 100-120°C, manufactured by BAXENDEN

[0150] ※4TKA-B75S: Duranate TKA-B75S, a blocked isocyanate with an isocyanurate structure, including trimers, dissociates at 130°C, manufactured by Asahi Kasei Corporation

[0151] ※5jER828, bisphenol A epoxy resin, manufactured by Mitsubishi Chemical Corporation

[0152] ※6N-770: EPICLON N-770, multifunctional phenol novolac type epoxy resin, manufactured by DIC Corporation

[0153] ※7Celloxide2021P: Bifunctional alicyclic epoxy resin, manufactured by Daicel Corporation

[0154] ※8CR-97: Rutile titanium oxide, average particle size 0.25μm, manufactured by Ishihara Sangyo Co., Ltd.

[0155] ※9CR-58: Rutile titanium oxide, average particle size 0.28μm, manufactured by Ishihara Sangyo Co., Ltd.

[0156] Characteristic test:

[0157] 1) Reflectivity

[0158] Each composition of the Examples and Comparative Examples was applied to the entire surface of a copper-clad laminate by screen printing (dry coating thickness 25 to 30 μm) and then heat-cured at 150°C for 60 minutes. The cured film was then measured for reflectance at a wavelength of 460 nm using a spectrocolorimeter (CM-2600d, manufactured by Konica Minolta Sensing, Inc.).

[0159] 2) Discoloration resistance

[0160] The substrate obtained in the reflectance test was heat-treated at 200°C for 30 minutes and 60 minutes, and the change rate ΔE of the cured film before and after the treatment was determined using a colorimeter. The evaluation criteria are as follows.

[0161] <Discoloration resistance evaluation criteria>

[0162] ◎: ΔE is 2 or less

[0163] ○: ΔE is more than 2 and 3 or less

[0164] △: ΔE is more than 3 and less than 4

[0165] ×: ΔE is 4 or more

[0166] 3) Welding heat resistance

[0167] Each composition of the Examples and Comparative Examples was applied to a polyimide film (Duponts Kapton 100H) using an applicator and heat-cured in a hot air circulation oven at 150°C for 60 minutes to produce evaluation substrates having a cured film (dry film thickness 25-30 μm). The resulting evaluation substrates were immersed in a solder bath at 260°C, and the surface condition of the cured film was visually observed.

[0168] <Judgment criteria for soldering heat resistance>

[0169] ⊚: The cured film did not peel off even after immersion for 10 seconds was repeated three or more times.

[0170] ◯: Even after repeating 10-second immersion twice, the cured film did not peel off.

[0171] Δ: When immersion for 10 seconds was repeated twice, the cured film peeled off slightly.

[0172] ×: The cured film peeled off after one 10-second immersion.

[0173] 4) Acid resistance

[0174] Each composition of the Examples and Comparative Examples was applied to a polyimide film (Duponts Kapton 100H) using an applicator and heat-cured in a hot air circulation oven at 150°C for 60 minutes to produce evaluation substrates having a cured film (dry coating thickness 25-30 μm). The cured coatings on the evaluation substrates were immersed in 10 vol% H₂SO₄ at 20°C for 20 minutes and then immediately subjected to a tape peel test to evaluate bulging and peeling of the cured films.

[0175] ○: No bulging or peeling.

[0176] △: There is slight peeling.

[0177] ×: The cured film peeled off over a large area.

[0178] 5) Flexibility (bending test)

[0179] Each composition of the examples and comparative examples was applied onto a polyimide film (Duponts Kapton 100H) using an applicator and heat-cured in a hot air circulation oven at 150°C for 60 minutes to obtain an evaluation substrate having a cured film (dry coating thickness 25-30 μm).

[0180] The seam was repeatedly bent 180° multiple times, and the state of cracking in the cured film was observed visually and with an optical microscope at a magnification of 200. The number of times no cracking occurred was evaluated.

[0181] <Judgment Criteria>

[0182] ◎: 5 or more times

[0183] ○: 2-4 times

[0184] ×: Less than 1 time

[0185] The results of the above-mentioned evaluation tests are collectively shown in Table 2.

[0186] Table 2

[0187]

[0188] As is apparent from Table 2, Examples 1 to 6, which used in combination (A) a resin containing hydroxyl and carboxyl groups using a phenoxy resin as a starting material, (B) a blocked isocyanate compound, (C) an epoxy resin, and (D) titanium oxide, all achieved excellent results in the evaluation of reflectivity, discoloration resistance, soldering heat resistance, acid resistance, and flexibility.

[0189] In particular, it is believed that the use of novolac-type epoxy resins in Examples 3, 5, and 6 resulted in shorter crosslinking distances than the use of bisphenol A-type epoxy resins, leading to improved soldering heat resistance compared to Example 1. Furthermore, it is believed that the higher titanium oxide content in Examples 5 and 6 compared to Examples 1 and 2 resulted in superior discoloration resistance.

[0190] Furthermore, despite having a lower titanium oxide content, Examples 3 and 4 exhibited improved discoloration resistance compared to Examples 1 and 2. This is believed to be due to the use of a phenol novolac-type epoxy resin or an epoxy resin having an alicyclic skeleton as the epoxy resin.

[0191] It is considered that, since Example 4 used an epoxy resin having an alicyclic skeleton and no benzene ring skeleton, the flexibility was improved compared with Examples 1 and 2.

[0192] In contrast, Comparative Example 1, which did not contain epoxy resin (C), exhibited insufficient discoloration resistance, poor soldering heat resistance, and poor acid resistance. Comparative Example 2, which used a conventional curing system based on a combination of a polyester resin and an isocyanate compound, exhibited low reflectivity and poor discoloration resistance and acid resistance. Comparative Examples 3 and 4, which used epoxy resins containing hydroxyl and carboxyl groups starting from epoxy resins, exhibited low reflectivity, insufficient discoloration resistance, and poor flexibility.

[0193] These results demonstrate that the thermosetting resin composition of the present invention can form a cured product having high reflectivity and excellent discoloration resistance, heat resistance, acid resistance, and flexibility. The thermosetting resin composition of the present invention, dry films obtained using the composition, and cured products thereof are suitable for use in electronic components such as backlights for liquid crystal displays (LCDs) in portable devices, personal computers, and televisions, and light-emitting elements such as LEDs.

Claims

1. A thermosetting resin composition, characterized in that contain: (A) a resin containing hydroxyl groups and carboxyl groups using a phenoxy resin as a starting material, (B) blocked isocyanate compounds, (C) epoxy resin, and (D) titanium oxide, The resin (A) containing hydroxyl groups and carboxyl groups, which is prepared by reacting the hydroxyl groups of the phenoxy resin with at least one selected from the group consisting of tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride and hexahydrophthalic anhydride, The phenoxy resin has a mass average molecular weight (Mw) of 10,000 to 200,000.

2. The thermosetting resin composition according to claim 1, wherein The dissociation temperature of the blocking agent of the (B) blocked isocyanate compound is 100° C. or higher and 130° C. or lower.

3. The thermosetting resin composition according to claim 1 or 2, wherein The (B) blocked isocyanate compound includes a trimer.

4. The thermosetting resin composition according to claim 1 or 2, wherein The (A) resin containing hydroxyl groups and carboxyl groups using a phenoxy resin as a starting material is a resin containing hydroxyl groups and carboxyl groups using a bisphenol A type phenoxy resin as a starting material.

5. The thermosetting resin composition according to claim 1 or 2, wherein The amount of the blocked isocyanate compound (B) is 5 to 200 parts by mass based on 100 parts by mass of the resin (A) containing a hydroxyl group and a carboxyl group, which is prepared using a phenoxy resin as a starting material.

6. The thermosetting resin composition according to claim 1 or 2, wherein The amount of the epoxy resin (C) is 5 to 200 parts by mass based on 100 parts by mass of the resin (A) containing a hydroxyl group and a carboxyl group, which is prepared using a phenoxy resin as a starting material.

7. The thermosetting resin composition according to claim 1 or 2, wherein The amount of the titanium oxide (D) is 60 to 400 parts by mass based on 100 parts by mass of the resin (A) containing a hydroxyl group and a carboxyl group, which is prepared using a phenoxy resin as a starting material.

8. A dry film, characterized in that The present invention comprises a resin layer obtained from the thermosetting resin composition according to any one of claims 1 to 7.

9. A solidified product, characterized in that The resin layer of the thermosetting resin composition according to any one of claims 1 to 7 or the dry film according to claim 8 is cured. 10 . An electronic component comprising the cured product according to claim 9 .

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