UV-curable resin compositions, adhesives, sealants, insulating protective agents, and electronic circuit boards

Abstract

One ultraviolet-curable resin composition according to the present invention contains: at least one compound (A) that is selected from the group consisting of poly(meth)acrylates (a1) and polyvinyl ethers (a2); a compound (B) that has at least two thiol groups per molecule; a photoinitiator (C) that has an absorbance of 0.10 or more at 385 nm, obtained from a 10 mm path length cell of an acetonitrile solution at a concentration of 500 ppm; and a photosensitizer (D). The content of the compound (B), in terms of solid content, is 15 to 70 mass% per 100 mass% of the resin composition.

Description

[Technical Field]

[0001] The present invention relates to ultraviolet-curable resin compositions, adhesives, sealants, insulating protective agents, and electronic circuit boards. [Background technology]

[0002] UV-curable resin compositions generally harden when irradiated with ultraviolet light, as active radicals or acids are generated from the photopolymerization initiator, causing polymerization of polymerizable compounds such as (meth)acrylates and epoxy compounds. However, in environments where UV-curable resin compositions are used, if there are areas where light does not reach, such as shaded areas or narrow gaps (shaded areas), ultraviolet light cannot sufficiently reach the shaded areas, resulting in insufficient curing of the UV-curable resin composition. Furthermore, when obtaining thick coatings or deep molded products from UV-curable resin compositions, ultraviolet light cannot sufficiently reach the depths of these cured products, leading to insufficient curing in the deeper parts.

[0003] As a method for curing such light-shielded or deep areas, some commercially available UV-curable resins use a combination of UV curing and curing by heat or moisture. However, these curing resins are not always satisfactory due to problems such as deformation and reduced adhesion caused by heat, and the time-consuming nature of moisture curing.

[0004] As another method for curing the light-shielding portion, it has been considered to add a material that emits light of a wavelength that promotes the curing reaction to the UV-curable resin composition (Patent Documents 1-2). However, in the methods described in Patent Documents 1-2, the distance at which curing of the light-shielding portion was confirmed was only about 1 mm or less, and it has been difficult to cure the light-shielding portion to a practical level by UV irradiation alone. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2013 / 105162 [Patent Document 2] Japanese Patent Publication No. 2007-156184 [Overview of the project] [Problems that the invention aims to solve]

[0006] The object of this invention is to provide a novel UV-curable resin composition that can be sufficiently cured even in light-shielded areas and deep parts when cured by irradiation with ultraviolet light. [Means for solving the problem]

[0007] As a result of diligent research, the inventors have found that a composition comprising at least one selected from the group consisting of at least poly(meth)acrylates and polyvinyl ethers, a compound having a predetermined thiol group, a predetermined photopolymerization initiator, and a predetermined photosensitizer can contribute to solving the above-mentioned problems. Furthermore, as a result of further research and analysis by the inventors, they have found that the above-mentioned problems can be solved with high certainty by a composition containing a specific amount of the aforementioned compound having a thiol group, and thus the present invention has been completed.

[0008] One UV-curable resin composition of the present invention comprises at least one (A) selected from the group consisting of poly(meth)acrylate (a1) and polyvinyl ether (a2), A compound (B) having at least two thiol groups in its molecule, A photopolymerization initiator (C) whose absorbance at a path length of 10 mm in a 500 ppm acetonitrile solution is 0.10 or higher at 385 nm, It contains a photosensitizer (D), The content of compound (B) is 15% by mass or more and 70% by mass or less, based on the solid content, relative to 100% by mass of the resin composition.

[0009] Furthermore, in one more preferred invention of the above-described invention, component (B) is a compound having at least three thiol groups in its molecule.

[0010] Furthermore, in one of the more preferred inventions described above, the content of component (D) is 0.0001% by mass or more and 0.02% by mass or less, based on solid content, per 100% by mass of the resin composition.

[0011] Furthermore, in one of the more preferred inventions described above, component (D) is at least one selected from the group consisting of benzophenone compounds, thioxanthone compounds, naphthalene compounds, and anthracene compounds.

[0012] Furthermore, in one of the more preferred inventions described above, component (C) is at least one compound selected from the group consisting of alkylphenone compounds and acylphosphine oxide compounds.

[0013] Furthermore, in each of the above-described inventions, one more preferred invention further comprises a polymerization inhibitor (E).

[0014] Furthermore, in one of the more preferred inventions described above, component (E) is at least one selected from the group consisting of N-nitrosophenylhydroxylamine aluminum salt and phenothiazine.

[0015] Furthermore, in each of the above-described inventions, one more preferred application example is an adhesive containing the ultraviolet-curable resin composition of each of the above-described inventions.

[0016] Furthermore, in each of the above-described inventions, one more preferred application example is a encapsulant containing the ultraviolet-curable resin composition of each of the above-described inventions.

[0017] Furthermore, in each of the above-described inventions, one more preferred application example is an insulating protective agent containing the ultraviolet-curable resin composition of each of the above-described inventions.

[0018] Furthermore, in each of the above-described inventions, one more preferred application example is an electronic circuit board containing the insulating protective agent of each of the above-described inventions. [Effects of the Invention]

[0019] One UV-curable resin composition of the present invention can be sufficiently cured by UV irradiation even when there are light-shielding areas. Furthermore, one UV-curable resin composition of the present invention can be sufficiently cured even in the deep parts of cured products such as thick coatings and deep molded products. Moreover, one UV-curable resin composition of the present invention exhibits excellent curability in light-shielding areas and deep parts even when cured using UV light from a UV-LED light source.

[0020] One UV-curable resin composition of the present invention exhibits excellent curing properties in light-shielded areas and deep areas, making it suitable as an adhesive used in shaded areas and narrow gaps, such as an adhesive used between a protective panel and a touch panel in an image display device, or an adhesive used for joining various electronic components on an electronic circuit board.

[0021] One UV-curable resin composition of the present invention exhibits excellent curability in light-shielding areas and deep within, making it suitable as a sealant for parts with complex shapes that are difficult to expose to UV light, or as a sealant in which a shielding area exists in the operating environment, such as a sealant used in optical lens units, a sealant for leaded electronic components, and an underfill agent.

[0022] One UV-curable resin composition of the present invention exhibits excellent curability in light-shielded areas and deep within, making it suitable as an insulating protective agent for use in electronic circuit boards on which electronic components are mounted. [Brief explanation of the drawing]

[0023] [Figure 1] This is a schematic diagram showing the evaluation of the hardening properties of the shaded area in the example, when a spacer is placed on the FRP substrate. [Figure 2]This is a schematic diagram showing the evaluation of the shaded curing properties of the example, when the UV-curable resin composition is applied to the portion not covered by the spacer. [Figure 3] This is a schematic diagram showing the evaluation of the shaded area curing properties in the example, when a PET film is laminated. [Figure 4] This is a schematic diagram showing the evaluation of the shaded area curing properties in the example, when a light-shielding plate is placed. [Figure 5] This is a schematic diagram showing the evaluation of the shaded area curing properties in the example, when the light-shielding plate and PET film are peeled off after UV irradiation. [Figure 6] This is a schematic cross-sectional view of the example during UV irradiation, used to evaluate the curability in the shaded area. [Modes for carrying out the invention]

[0024] [Ultraviolet curable resin composition] One UV-curable resin composition of this embodiment comprises at least one selected from the group consisting of poly(meth)acrylate (a1) (hereinafter referred to as component (a1)) and polyvinyl ether (a2) (hereinafter referred to as component (a2)) (hereinafter referred to as component (A)), a compound (B) (hereinafter referred to as component (B)) having at least two thiol groups in its molecule, a photopolymerization initiator (C) (hereinafter referred to as component (C)) having an absorbance of 0.10 or more at 385 nm in a 500 ppm acetonitrile solution with a path length of 10 mm, and a photosensitizer (D) (hereinafter referred to as component (D)).

[0025] In this application, "(meth)acrylic" means "at least one selected from the group consisting of acrylic and methacrylic." Similarly, "(meth)acrylate" means "at least one selected from the group consisting of acrylate and methacrylate," and "(meth)acryloyl group" means "at least one selected from the group consisting of acryloyl group and methacryloyl group."

[0026] <Poly(meth)acrylate(a1)> (a1) Component can be any known compound having at least two (meth)acryloyl groups in its molecule, without any particular limitations. Component (a1) may be used alone or in combination of two or more. In addition, the poly(meth)acrylate of this embodiment may also be used together with the polyvinyl ether described later. Even when the poly(meth)acrylate and the polyvinyl ether are used together, the same effects as those of this embodiment can be achieved.

[0027] (a1) Typical examples of components include, but are not limited to, alkylene glycol poly(meth)acrylate, polyalkylene glycol poly(meth)acrylate, glycerin poly(meth)acrylate, polyglycerin poly(meth)acrylate, pentaerythritol poly(meth)acrylate, polypentaerythritol poly(meth)acrylate, trimethylolpropane poly(meth)acrylate, polymethylolpropane poly(meth)acrylate, ethylene oxide-modified isocyanurate di(meth)acrylate, ethylene oxide-modified isocyanurate tri(meth)acrylate, propylene oxide-modified isocyanurate di(meth)acrylate, propylene oxide-modified isocyanurate tri(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, urethane (meth)acrylate, polyester (meth)acrylate, epoxy (meth)acrylate, polyether (meth)acrylate, polyacrylic (meth)acrylate, etc.

[0028] Typical examples of the alkylene glycol poly(meth)acrylates mentioned above include, but are not limited to, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, but also include but are not limited to, but also include but are not limited to, but ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, and 1,6-hexanediol di(meth)acrylate.

[0029] Typical examples of the above-mentioned polyalkylene glycol poly(meth)acrylates include, but are not limited to, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, and polypropylene glycol di(meth)acrylate.

[0030] Typical examples of the above-mentioned glycerin poly(meth)acrylate include, but are not limited to, glycerin di(meth)acrylate, glycerin tri(meth)acrylate, ethylene oxide-modified glycerin di(meth)acrylate, propylene oxide-modified glycerin di(meth)acrylate, ethylene oxide-modified glycerin tri(meth)acrylate, propylene oxide-modified glycerin tri(meth)acrylate, and mixtures consisting of at least two selected from the group consisting of glycerin mono(meth)acrylate, glycerin di(meth)acrylate, and glycerin tri(meth)acrylate.

[0031] Typical examples of the polyglycerin poly(meth)acrylates mentioned above include, but are not limited to, diglycerin di(meth)acrylate, diglycerin tri(meth)acrylate, diglycerin tetra(meth)acrylate, triglycerin di(meth)acrylate, triglycerin tri(meth)acrylate, triglycerin tetra(meth)acrylate, and triglycerin penta(meth)acrylate.

[0032] Typical examples of the above-mentioned pentaerythritol poly(meth)acrylate include, but are not limited to, a mixture of at least two selected from the group consisting of pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethylene oxide-modified pentaerythritol di(meth)acrylate, propylene oxide-modified pentaerythritol di(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate, propylene oxide-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified pentaerythritol tetra(meth)acrylate, propylene oxide-modified pentaerythritol tetra(meth)acrylate, and a mixture of at least two selected from the group consisting of pentaerythritol mono(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate.

[0033] Typical examples of the above polypentaerythritol poly(meth)acrylate include dipentaerythritol di(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol di(meth)acrylate, tripentaerythritol tri(meth)acrylate, and tripentaerythritol tetra(meth)acrylate. This includes, but is not limited to, (meth)acrylates, tripentaerythritol penta(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, tripentaerythritol octa(meth)acrylate, and mixtures consisting of at least two selected from these (meth)acrylates, mixtures of dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate, etc.

[0034] Typical examples of the above-mentioned trimethylolpropane poly(meth)acrylates include trimethylolpropanedi(meth)acrylate, trimethylolpropanetri(meth)acrylate, ethylene oxide-modified trimethylolpropanedi(meth)acrylate, propylene oxide-modified trimethylolpropanedi(meth)acrylate, ethylene oxide-modified trimethylolpropanetri(meth)acrylate, propylene oxide-modified trimethylolpropanetri(meth)acrylate, etc., but are not limited to these.

[0035] Typical examples of the above-mentioned polytrimethylolpropane poly(meth)acrylate include ditrimethylolpropanedi(meth)acrylate, ditrimethylolpropanetri(meth)acrylate, and ditrimethylolpropanetetra(meth)acrylate, but are not limited to these.

[0036] (Urethane (meth)acrylate) Typical examples of the above-mentioned urethane (meth)acrylates include reaction products of hydroxyl group-containing (meth)acrylate and polyisocyanate, and reaction products of hydroxyl group-containing (meth)acrylate, polyol, and polyisocyanate, but are not limited to these.

[0037] The above-mentioned hydroxyl group-containing (meth)acrylate can be any known compound having at least one hydroxyl group in its molecule, without any particular limitations. The hydroxyl group-containing (meth)acrylate may be used alone or in combination of two or more types.

[0038] Typical examples of the hydroxyl group-containing (meth)acrylates mentioned above include, but are not limited to, hydroxyl group-containing mono(meth)acrylates and hydroxyl group-containing poly(meth)acrylates.

[0039] Typical examples of the hydroxyl group-containing mono(meth)acrylates mentioned above include, but are not limited to, hydroxyl group-containing linear alkyl(meth)acrylates, hydroxyl group-containing branched alkyl(meth)acrylates, hydroxyl group-containing cycloalkyl(meth)acrylates, hydroxyl group-containing aryl(meth)acrylates, polyalkylene glycol mono(meth)acrylates, glycerin mono(meth)acrylates, ethylene oxide-modified glycerin mono(meth)acrylates, propylene oxide-modified glycerin mono(meth)acrylates, trimethylolpropane mono(meth)acrylates, and caprolactone adducts of these mono(meth)acrylates.

[0040] Typical examples of the hydroxyl group-containing linear alkyl (meth)acrylates mentioned above include, but are not limited to, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0041] Typical examples of the hydroxyl group-containing branched alkyl (meth)acrylates mentioned above include, but are not limited to, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 3-hydroxybutyl (meth)acrylate.

[0042] Typical examples of the hydroxyl group-containing cycloalkyl (meth)acrylates mentioned above include, but are not limited to, 1,4-cyclohexanedimethanol mono(meth)acrylate. Typical examples of the hydroxyl group-containing aryl (meth)acrylates mentioned above include, but are not limited to, 1,4-benzenedimethanol mono(meth)acrylate.

[0043] Typical examples of the above-mentioned polyalkylene glycol mono(meth)acrylates include (meth)acrylates having oxyalkylene chains such as dipropylene glycol mono(meth)acrylate, diethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and polyethylene glycol mono(meth)acrylate; (meth)acrylates having block-structured oxyalkylene chains such as polyethylene glycol-polypropylene glycol mono(meth)acrylate and polyoxybutylene-polyoxypropylene mono(meth)acrylate; and (meth)acrylates having random-structured oxyalkylene chains such as poly(ethylene glycol-tetramethylene glycol) mono(meth)acrylate and poly(propylene glycol-tetramethylene glycol) mono(meth)acrylate, but are not limited to these.

[0044] Typical examples of the above-mentioned hydroxyl group-containing poly(meth)acrylates include, but are not limited to, compounds of the above-mentioned alkylene glycol poly(meth)acrylate, polyalkylene glycol poly(meth)acrylate, glycerin poly(meth)acrylate, polyglycerin poly(meth)acrylate, pentaerythritol poly(meth)acrylate, polypentaerythritol poly(meth)acrylate, trimethylolpropane poly(meth)acrylate, and polymethylolpropane poly(meth)acrylate that have at least one hydroxyl group in their molecule.

[0045] In the typical examples of the hydroxyl group-containing (meth)acrylates described above, hydroxyl group-containing (meth)acrylates having at least three (meth)acryloyl groups in the molecule are preferred from the viewpoint of excellent curability and scratch resistance of the cured film, and hydroxyl group-containing (meth)acrylates having one hydroxyl group and at least three (meth)acryloyl groups in the molecule are more preferred. Among the hydroxyl group-containing (meth)acrylates described above, hydroxyl group-containing pentaerythritol poly(meth)acrylates and hydroxyl group-containing polypentaerythritol poly(meth)acrylates are preferred from the viewpoint of excellent curability and scratch resistance of the cured film.

[0046] In the typical examples of polyisocyanates described above, any known compound having at least two isocyanate groups in its molecule can be used without particular limitation. One type of polyisocyanate may be used alone, or two or more types may be used in combination.

[0047] Typical examples of the polyisocyanates mentioned above include, but are not limited to, linear aliphatic diisocyanates, branched aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, biuret, isocyanurate, allophanate, and adduct forms of these diisocyanates, and complexes obtained by the reaction of two or more selected from the group consisting of biuret, isocyanurate, allophanate, and adduct forms.

[0048] Typical examples of the linear aliphatic diisocyanates mentioned above include, but are not limited to, methylene diisocyanate, ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, and decamethylene diisocyanate.

[0049] Typical examples of the branched aliphatic diisocyanates mentioned above include, but are not limited to, diethylpentylene diisocyanate, trimethylbutylene diisocyanate, trimethylpentylene diisocyanate, and trimethylhexamethylene diisocyanate.

[0050] Typical examples of the above-mentioned alicyclic diisocyanates include, but are not limited to, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, isophorone diisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, cycloheptylene diisocyanate, cyclodecylene diisocyanate, tricyclodecylene diisocyanate, adamantane diisocyanate, norbornene diisocyanate, and bicyclodecylene diisocyanate.

[0051] Typical examples of the above aromatic diisocyanates include, but are not limited to, dialkyldiphenylmethane diisocyanates such as 4,4'-diphenyldimethylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanates such as 4,4'-diphenyltetramethylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-dibenzyli isocyanate, 1,3-phenylenedi isocyanate, 1,4-phenylenedi isocyanate, tolylene diisocyanate, xylylene diisocyanate, m-tetramethylxylylene diisocyanate, and 1,5-naphthylene diisocyanate.

[0052] A typical example of the biuret compound of the above diisocyanate is: The following structural formula: [ka] [where n b is an integer greater than or equal to 1, and R bA ~R bE Each of these is independently one or more selected from the group consisting of linear aliphatic diisocyanate residues, branched aliphatic diisocyanate residues, alicyclic diisocyanate residues, and aromatic diisocyanate residues, R bα ~R bβ Each of these independently comprises an isocyanate group or [ka] (n b1 is a non-negative integer, and Rb1 ~R b5 is R bA ~R bE and R b '~R b '' are each independently an isocyanate group or R bα ~R bβ is a group of itself. R b4 ~R b5 and R b '' may have different groups for each constitutional unit). R bD ~R bE , R bβ may have different groups for each constitutional unit], a compound represented by the formula, etc.

[0053] Specific examples of the biuret form of the diisocyanate include, but are not limited to: Duranate 24A-100, Duranate 22A-75P, Duranate 21S-75E (all manufactured by Asahi Kasei Corporation), Desmodur N3200A (biuret form of hexamethylene diisocyanate) (manufactured by Sumika Covestro Urethane Co., Ltd.), etc.

[0054] Representative examples of the isocyanurate form of the diisocyanate are: The following structural formula:

Chemical Formula

Chemical Formula

[0055] Typical examples of the isocyanurate derivatives of the above-mentioned diisocyanates include, but are not limited to, Duranate TPA-100, Duranate TKA-100, Duranate MFA-75B, Duranate MHG-80B (all manufactured by Asahi Kasei Corporation), Coronate HXR, Coronate HX (both isocyanurate derivatives of hexamethylene diisocyanate) (both manufactured by Tosoh Corporation), Takenate D-127N (isocyanurate derivative of hydrogenated xylylene diisocyanate) (both manufactured by Mitsui Chemicals, Inc.), and Vestanat T1890 / 100 (isocyanurate derivative of isophorone diisocyanate) (both manufactured by Evonik Japan Co., Ltd.).

[0056] A typical example of the allophanate derivative of the above diisocyanate is: The following structural formula: [ka] [where n a is a non-negative integer, and R aA R is an alkyl group, an allyl group, a polyethylene group, a polyester group, or a polycarbonate group. aB ~R aG Each of these is independently one or more selected from the group consisting of linear aliphatic diisocyanate residues, branched aliphatic diisocyanate residues, alicyclic diisocyanate residues, and aromatic diisocyanate residues, R aα ~R aγEach of these independently comprises an isocyanate group or [ka] (n a1 is a non-negative integer, and R a1 ~R a6 is R aB ~R aG It is similar to R a '~R a Each of ''' is independently an isocyanate group or R aα ~R aγ It is the foundation of itself. R a1 ~R a4 and R a '~R a ''' may have different bases for each constituent unit. ) aB ~R aE and R aα ~R aγ The compounds represented by [ ] may have different groups for each constituent unit, but are not limited to these.

[0057] Typical examples of the allophanate derivatives of the above-mentioned diisocyanates include Coronate 2793 (manufactured by Tosoh Corporation) and Takenate D-178N (manufactured by Mitsui Chemicals, Inc.), but are not limited to these.

[0058] A typical example of the above-mentioned adduct of the diisocyanate is, The following structural formula: [ka] [where n ad is a non-negative integer, and R adA ~R adE Each of these is independently one or more selected from the group consisting of linear aliphatic diisocyanate residues, branched aliphatic diisocyanate residues, alicyclic diisocyanate residues, and aromatic diisocyanate residues, R ad1 ~R ad2 Each is independent [ka] (wherein n ad’ is an integer of 0 or greater, R ad’ to R ad’’ are the same as R adA to R adE , R ad’’’ is R ad1 to R ad2 itself, and R ad’ to R ad’’’ may have different groups for each constitutional unit.) , and R adD to R adE , R ad2 may have different groups for each constitutional unit.]] an adduct of trimethylolpropane and diisocyanate represented by, the following structural formula

Chemical Formula

Chemical Formula

[0059] Typical examples of the above-mentioned diisocyanate adducts include, but are not limited to, Duranate P301-75E (manufactured by Asahi Kasei Corporation), Takenate D-110N, Takenate D-160N (manufactured by Mitsui Chemicals, Inc.), Coronate L, Coronate HL (manufactured by Tosoh Corporation).

[0060] In each of the above formulas, "linear aliphatic diisocyanate residue, branched aliphatic diisocyanate residue, alicyclic diisocyanate residue, and aromatic diisocyanate residue" means the remaining groups from the above linear aliphatic diisocyanate, branched aliphatic diisocyanate, alicyclic diisocyanate, and aromatic diisocyanate, excluding the isocyanate group.

[0061] The above polyisocyanates are preferably those having at least three isocyanate groups in the molecule, from the viewpoint of excellent scratch resistance of the cured film. The biuret, isocyanurate, allophanate, and adduct forms of the polyisocyanates having at least three isocyanate groups in the molecule are preferred.

[0062] The above polyol can be any known compound having at least two hydroxyl groups in its molecule, without any particular limitations. One polyol may be used alone, or two or more may be used in combination.

[0063] Typical examples of the above polyols include, but are not limited to, aliphatic polyols, alicyclic polyols, polyether polyols, polyester polyols, polycarbonate polyols, polyolefin polyols, polybutadiene polyols, and (meth)acrylic polyols.

[0064] Typical examples of the above aliphatic polyols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, dimethylolpropane, neopentyl glycol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-tetramethylenediol, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol, 1,5-pentamethylenediol, and 1,6-hex This includes, but is not limited to, aliphatic alcohols containing two hydroxyl groups, such as shark methyldiol, 3-methyl-1,5-pentamethylenediol, 2,4-diethyl-1,5-pentamethylenediol, pentaerythritol diacrylate, 1,9-nonanediol, and 2-methyl-1,8-octanediol; sugar alcohols such as xylitol and sorbitol; and aliphatic alcohols containing three or more hydroxyl groups, such as glycerin, trimethylolpropane, and trimethylolethane.

[0065] Typical examples of the above-mentioned alicyclic polyols include, but are not limited to, cyclohexanediols such as 1,4-cyclohexanediol and cyclohexyldimethanol, hydrogenated bisphenols such as hydrogenated bisphenol A, and tricyclodecanedimethanol.

[0066] Typical examples of the above-mentioned polyether-based polyols include, but are not limited to, polyalkylene glycols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutylene glycol, polypentamethylene glycol, and polyhexamethylene glycol, as well as random or block copolymers of these polyalkylene glycols.

[0067] Typical examples of the above-mentioned polyester polyols include, but are not limited to, condensation polymers of polyhydric alcohols and polycarboxylic acids or their anhydrides; ring-opening polymers of cyclic esters (lactones); and reaction products of three components: polyhydric alcohols, polycarboxylic acids or their anhydrides, and cyclic esters.

[0068] Typical examples of the polyhydric alcohols mentioned above include, but are not limited to, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylenediol, 1,3-tetramethylenediol, 2-methyl-1,3-trimethylenediol, 1,5-pentamethylenediol, neopentyl glycol, 1,6-hexamethylenediol, 3-methyl-1,5-pentamethylenediol, 2,4-diethyl-1,5-pentamethylenediol, glycerin, trimethylolpropane, trimethylolethane, cyclohexanediols (such as 1,4-cyclohexanediol), bisphenols (such as bisphenol A), and sugar alcohols (such as xylitol and sorbitol).

[0069] Typical examples of the polycarboxylic acids or their anhydrides mentioned above include, but are not limited to, aliphatic dicarboxylic acids such as malonic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedionic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, paraphenylenedicarboxylic acid, and trimellitic acid, or their anhydrides.

[0070] Typical examples of the above-mentioned cyclic esters include, but are not limited to, propiolactone, buttyrolactone, valerolactone, β-methyl-δ-valerolactone, and ε-caprolactone.

[0071] Typical examples of the polycarbonate-based polyols mentioned above include reaction products of polyhydric alcohols and phosgene; and ring-opening polymers of cyclic carbonate esters (such as alkylene carbonates), but are not limited to these.

[0072] Typical examples of the above-mentioned polyhydric alcohols include the polyhydric alcohols exemplified in the above-mentioned polyester polyols, and typical examples of the above-mentioned alkylene carbonates include, but are not limited to, ethylene carbonate, trimethylene carbonate, tetramethylene carbonate, and hexamethylene carbonate.

[0073] The above-mentioned polycarbonate polyol may be any compound having a carbonate bond within its molecule and a hydroxyl group at its terminus, and may also have an ester bond in addition to the carbonate bond.

[0074] Typical examples of the polyolefin-based polyols mentioned above include, but are not limited to, those having a homopolymer or copolymer of ethylene, propylene, butene, etc. as a saturated hydrocarbon backbone, and having hydroxyl groups at the molecular ends.

[0075] Typical examples of the polybutadiene polyols mentioned above include those having a butadiene copolymer as the hydrocarbon backbone and hydroxyl groups at their molecular ends, but are not limited to these. The polybutadiene polyol may also be a hydrogenated polybutadiene polyol in which all or some of the ethylenically unsaturated groups contained in its structure are hydrogenated.

[0076] Typical examples of the above (meth)acrylic polyols include, but are not limited to, polymers or copolymers of (meth)acrylic acid esters having at least two hydroxyl groups in the molecule. Typical examples of the above (meth)acrylic acid esters include, but are not limited to, alkyl (meth)acrylate esters such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, and octadecyl (meth)acrylate.

[0077] In the above-mentioned urethane (meth)acrylate, the molar ratio (NCO:OH) of isocyanate groups contained in the polyisocyanate to hydroxyl groups contained in the hydroxyl group-containing (meth)acrylate and hydroxyl groups contained in the polyol is not particularly limited. However, a ratio of 1:1 to 10 is preferred, and a ratio of approximately 1:1 to 8 is more preferred, from the viewpoint of excellent balance between the flexibility and scratch resistance of the cured film.

[0078] The method for producing the above-mentioned urethane (meth)acrylate is not particularly limited as long as it involves reacting the above-mentioned hydroxyl group-containing (meth)acrylate, the above-mentioned polyisocyanate, and optionally the above-mentioned polyol, and various known production methods are exemplified. In specific examples, a method may be employed in which the hydroxyl group-containing (meth)acrylate, polyisocyanate, and optionally the polyol are reacted in the presence of a catalyst at an appropriate reaction temperature (e.g., 60-90°C). Furthermore, the order in which the hydroxyl group-containing (meth)acrylate, polyisocyanate, and polyol are reacted is not particularly limited, and methods may be employed in which they are mixed and reacted as desired, or in which all components are mixed and reacted together, etc., but are not limited to these.

[0079] Typical examples of the catalysts mentioned above include organotin catalysts such as dibutyltin dilaurate and dioctyltin dilaurate, organic tin acids such as tin octoate, organic titanium catalysts such as titanium ethyl acetate, organic zirconium catalysts such as zirconium tetraacetylacetonate, and organic iron catalysts such as iron acetylacetonate, but are not limited to these. The catalysts may be used individually or in combination of two or more.

[0080] (Polyester (meth)acrylate) Typical examples of the above-mentioned polyester (meth)acrylates include, but are not limited to, dehydrated condensates of the above-mentioned polyester polyol and (meth)acrylic acid.

[0081] (Epoxy (meth)acrylate) Typical examples of the epoxy (meth)acrylates mentioned above include compounds obtained by the addition reaction between the terminal epoxy groups of epoxy resins and (meth)acrylic acid, but are not limited to these. Examples of epoxy resins include aromatic epoxy resins and aliphatic epoxy resins, but are not limited to these.

[0082] Typical examples of the above aromatic epoxy resins include, but are not limited to, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenol type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A type novolac type epoxy resin, naphthalenediol type epoxy resin, phenol dicyclopentadiene novolac type epoxy resin, and their hydrides.

[0083] Typical examples of the above-mentioned aliphatic epoxy resins include, but are not limited to, diglycidyl ethers of alkylene glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, and 1,6-hexanediol; diglycidyl ethers of polyalkylene glycols such as polyethylene glycol and polypropylene glycol; diglycidyl ethers of neopentyl glycol, dibromo-neopentyl glycol, and their alkylene oxide adducts; di or triglycidyl ethers of polyhydric alcohols such as trimethylolethane, trimethylolpropane, glycerin, and their alkylene oxide adducts, and di, tri or tetraglycidyl ethers of pentaerythritol and its alkylene oxide adducts; di or polyglycidyl ethers of hydrogenated bisphenol A and its alkylene oxide adducts; tetrahydrophthalic acid diglycidyl ether; hydroquinone diglycidyl ether, etc.

[0084] (Polyether(meth)acrylate) Typical examples of the above-mentioned polyether (meth)acrylates include, but are not limited to, dehydration condensates of the above-mentioned polyether-based polyol and (meth)acrylic acid.

[0085] (Polyacrylic (meth)acrylate) Typical examples of the polyacrylic (meth)acrylates mentioned above include epoxy group-containing mono(meth)acrylates, and, if necessary, acrylic copolymers obtained by polymerizing mono(meth)acrylates, and reaction products of (meth)acrylic acid, but are not limited to these.

[0086] Typical examples of the epoxy group-containing mono(meth)acrylates mentioned above include, but are not limited to, glycidyl(meth)acrylate, β-methylglycidyl(meth)acrylate, 3,4-epoxycyclohexylmethyl(meth)acrylate, and vinylcyclohexene monooxide (i.e., 1,2-epoxy-4-vinylcyclohexane).

[0087] (a1) From the viewpoint of curing properties, the preferred components are trimethylolpropane poly(meth)acrylate, ditrimethylolpropane poly(meth)acrylate, pentaerythritol (poly)acrylate, and dipentaerythritol poly(meth)acrylate.

[0088] <Polyvinyl ether (a2)> Furthermore, component (a2) can be any known vinyl ether compound having at least two vinyl groups in its molecule, without any particular limitations.

[0089] Typical examples of component (a2) include, but are not limited to, ethylene glycol divinyl ether, diethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide divinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, and dipentaerythritol hexanyl ether.

[0090] (Properties of poly(meth)acrylate(a1)) The physical properties of component (a1) are not particularly limited. The number of intramolecular (meth)acryloyl groups in component (a1) is preferably at least 3, and more preferably 3 to 15, from the viewpoint of excellent hardness of the cured film.

[0091] The content of component (a1) in the above UV-curable resin composition is not particularly limited, but from the standpoint of excellent moisture and heat resistance and appearance, it is preferable that it be 25% to 80% by mass based on the solid content, relative to 100% by mass of the UV-curable resin composition.

[0092] (Physical properties of polyvinyl ether (a2)) (a2) The physical properties of component (a2) are not particularly limited. The number of vinyl groups in the molecule of component (a2) is preferably at least 3, and more preferably 3 to 15, from the viewpoint of excellent hardness of the cured film.

[0093] The content of component (a2) in the above UV-curable resin composition is not particularly limited, but from the standpoint of excellent moisture and heat resistance and appearance, it is preferable that it be 25% to 85% by mass on a solid content basis, relative to 100% by mass of the UV-curable resin composition.

[0094] <Compound (B) having at least two thiol groups in its molecule> Component (B) can be any known compound having at least two thiol groups in its molecule, without any particular limitations. Component (B) may be used alone or in combination of two or more.

[0095] Because component (B) has at least two thiol groups in its molecule, the UV-curable resin composition exhibits excellent curing properties in both the shielded and deeper parts. On the other hand, if a compound having one thiol group in its molecule is used instead of component (B), the curing of the shielded and deeper parts of the UV-curable resin composition will be insufficient.

[0096] Typical examples of component (B) are compounds represented by the following general formulas (1) and (2), but are not limited to these.

[0097] [ka] (In the formula, X represents an n-valent organic group, and n is an integer between 2 and 6.)

[0098] [ka] (In the formula, Y represents an m-valence organic group, and m represents an integer from 2 to 6.)

[0099] (B) Typical examples of component (B) include, but are not limited to, 1,4-bis(3-mercaptobutyryloxy)butane, 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, trimethylolpropane tris(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptobutyrate), trimethylolpropane tris(3-mercaptopropionate), tris-[3-mercaptopropionyloxy]-ethyl]-isocyanurate, pentaerythritol tetrakis(3-mercaptopropionate), tetraethylene glycol bis(3-mercaptopropionate), dipentaerythritol hexakis(3-mercaptopropionate), etc.

[0100] Furthermore, component (B) is not limited to general formulas (1) and (2), but also includes, for example, 1,3-dimercapto-2-propanol, 2,2-bis(mercaptomethyl)-1,3-propanediol, 3-mercapto-2,2-bis(mercaptomethyl)-1-propanol, 2,2-bis(mercaptomethyl)-1,3-propanedithiol, 2-ethyl-2-(mercaptomethyl)-1,3-propanedithiol, and polysilsesquioxane-based polythiols obtained by condensing 3-mercaptopropyltrimethoxysilane, but is not limited to these.

[0101] Component (B) is more preferably at least one compound selected from the group consisting of 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, trimethylolpropanetris(3-mercaptobutyrate), pentaerythritoltetrakis(3-mercaptobutyrate), and pentaerythritoltetrakis(3-mercaptopropionate), due to its excellent curability in the shielded and deep parts.

[0102] (Physical properties of compound (B) having at least two thiol groups in its molecule) The physical properties of component (B) are not particularly limited. The number of thiol groups in the molecule of component (B) is preferably at least 3, and more preferably 3 to 4, from the viewpoint of excellent curability in the shielded area and deep parts.

[0103] The thiol group in component (B) is not particularly limited and may be one or more of a primary thiol group, a secondary thiol group, and a tertiary thiol group.

[0104] A typical example of the content of component (B) in the above UV-curable resin composition is, on a solid content basis, 15% by mass or more (more narrowly, greater than 15% by mass) and 70% by mass or less (more narrowly, less than 70% by mass) per 100% by mass of the UV-curable resin composition. When the content of component (B) is 15% by mass or more (more narrowly, greater than 15% by mass), the UV-curable resin composition exhibits excellent curability in shielded areas and deep areas. From the viewpoint of more reliably improving curability in shielded areas and deep areas, the lower limit of the above numerical range is preferably 30% by mass or more (more narrowly, greater than 30% by mass), and more preferably 50% by mass or more (more narrowly, greater than 50% by mass). On the other hand, when the content of component (B) is 70% by mass or less (more narrowly, less than 70% by mass), the cured product exhibits excellent chemical resistance. From the viewpoint of more accurately improving the chemical resistance of the cured product, the upper limit of the aforementioned numerical range is preferably 40% by mass or less (more narrowly, less than 40% by mass), and more preferably 20% by mass or less (more narrowly, less than 20% by mass). Therefore, the upper and lower limits can be determined based on mutually independent viewpoints to obtain more suitable values. For example, if more suitable values ​​are applied to both the upper and lower limits, one suitable numerical range for the content of component (B) is 20% by mass or more (more narrowly, greater than 20% by mass) and 50% by mass or less (more narrowly, less than 50% by mass). Furthermore, if more suitable values ​​are applied to both the upper and lower limits, one suitable numerical range for the content of component (B) is 40% by mass or more (more narrowly, greater than 40% by mass) and 50% by mass or less (more narrowly, less than 50% by mass).

[0105] The content of component (B) in the above UV-curable resin composition is preferably 25% to 70% by mass, based on solid content, relative to 100% by mass of the UV-curable resin composition, and more preferably 50% to 70% by mass, from the same viewpoint as excellent curing performance in shielded areas and deep areas.

[0106] In the above UV-curable resin composition, the molar ratio ((meth)acryloyl group:thiol group) of the (meth)acryloyl group contained in component (a1) and the thiol group contained in component (B) is not particularly limited, but a ratio of 1:0.5 to 1.5 is preferred, and a ratio of approximately 1:0.8 to 1.2 is more preferred, from the viewpoint of excellent curing performance in shielded areas and deep parts.

[0107] In the above UV-curable resin composition, the molar ratio (vinyl group:thiol group) of vinyl groups contained in component (a2) and thiol groups contained in component (B) is not particularly limited, but a ratio of 1:0.5 to 1.5 is preferred, and a ratio of 1:0.8 to 1.2 is more preferred, from the viewpoint of excellent curing performance in shielded areas and deep parts.

[0108] <Photopolymerization initiator (C)> Component (C) can be any known component without particular limitation, as long as its absorbance at a 500 ppm acetonitrile solution with a path length of 10 mm is 0.10 or higher at 385 nm. Component (C) may be used alone or in combination of two or more types.

[0109] Typical examples of component (C) include alkylphenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, etc., but are not limited to these.

[0110] Typical examples of the alkylphenone compounds mentioned above include, but are not limited to, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one and 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one.

[0111] Typical examples of the above-mentioned acylphosphine oxide compounds include, but are not limited to, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide.

[0112] Typical examples of the above oxime ester compounds include, but are not limited to, 1-[4-(phenylthio)]-1,2-octanedione-2-(O-benzoyl oxime), 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]ethanone-1-(O-acetyl oxime), and mixtures of oxyphenyl-acetyl acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester and oxyphenyl-acetyl acid 2-[2-hydroxy-ethoxy]-ethyl ester.

[0113] Component (C) is preferably at least one compound selected from the group consisting of alkylphenone compounds and acylphosphine oxide compounds, in terms of excellent curability in the shielded area and deep areas. Similarly, it is more preferably at least one compound selected from the group consisting of 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide.

[0114] (Physical properties of photopolymerization initiator (C)) Component (C) has an absorbance of 0.10 or higher at 385 nm when the optical path length of a 500 ppm acetonitrile solution is 10 mm. The absorbance of component (C) at 385 nm is obtained by preparing an acetonitrile solution of component (C) (concentration 500 ppm) and measuring the absorbance at 385 nm using a spectrophotometer with a 10 mm optical path length two-sided transmission quartz cell. A commercially available spectrophotometer can be used.

[0115] In recent years, from the standpoint of energy saving and space saving, light-emitting diodes (UV-LEDs) have been desired as ultraviolet (UV) light sources for ultraviolet curing. However, because UV-LEDs have relatively low energy, curing may be insufficient in some cases. Component (C) has an absorbance of 0.1 or higher at 385 nm, and therefore has sufficient absorption to ultraviolet light from a UV-LED light source (350-420 nm). Thus, even when using a UV-LED, the above UV-curable resin composition can be sufficiently cured.

[0116] The physical properties of component (C), other than the absorbance at 385 nm, are not particularly limited.

[0117] The content of component (C) in the above UV-curable resin composition is not particularly limited, but in terms of excellent curability in shielded areas and deep areas, it is preferably 0.1% by mass or more (more narrowly, greater than 0.1% by mass) and 15% by mass or less (more narrowly, less than 15% by mass) based on solid content, and more preferably 0.1% by mass or more (more narrowly, greater than 0.1% by mass) and 5% by mass or less (more narrowly, less than 5% by mass) based on 100% by mass of the UV-curable resin composition.

[0118] <Photosensitizer (D)> (D) Component is not particularly limited and various known components may be used without particular restriction. (D) Component may be used alone or two or more components may be used in combination.

[0119] Component (D) has the property of absorbing light (ultraviolet light) and transitioning to an electronically excited singlet state, and then transitioning to a triplet state through intersystem crossing.

[0120] The above UV-curable resin composition achieves sufficient curing in shielded areas and deep regions by using component (D). Although the details are unclear, the following reason is presumed: When the triplet state component (D) collides with the ground state component (C), energy transfer occurs, which promotes polymerization initiation (radical generation reaction) in component (C). Therefore, even in the shielded areas and deep regions where component (C) is present, polymerization initiation (radical generation reaction) is sufficiently expressed by component (D). As a result, it is presumed that the above UV-curable resin composition achieves sufficient curing in shielded areas and deep regions.

[0121] (D) Typical examples of components include, but are not limited to, benzophenone compounds, thioxanthone compounds, naphthalene compounds, anthracene compounds, anthraquinone compounds, benzoin compounds, and coumarin compounds.

[0122] Representative examples of the above benzophenone compounds include benzophenone, 2-methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 4-(methylphenylthio)phenylphenylmethane, 1-[4-(4-benzoylphenylsulfanyl)phenyl]-2-methyl-2-(4-methylphenylsulfonyl)propan-1-one, hydroxybenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, 4,4 These include, but are not limited to, '-aminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4-methoxy-4'-dimethylaminobenzophenone, p-dimethylaminobenzophenone, p-diethylaminobenzophenone, 2-hydroxy-4-alkoxybenzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, benzophenone ammonium salt, 1,4-dibenzoylbenzene, 2-benzoylnaphthalene, 4-benzoylbiphenyl, 4-benzoyldiphenyl ether, acrylic benzophenone, etc.

[0123] Typical examples of the thioxanthone compounds mentioned above include, but are not limited to, compounds represented by the general formula (3) below.

[0124] [ka] (In the formula, R1 represents a hydrogen atom, a linear or branched alkyl group having 1 to 20 carbon atoms, or a halogen atom.)

[0125] Typical examples of the thioxanthone compounds mentioned above include, but are not limited to, thioxanthone, 2-methylthioxanthone, 4-methylthioxanthone, 2-ethylthioxanthone, 4-ethylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, 2-chlorothioxanthone, 2,4-dichlorothioxanthone, 1-chloro-4-propoxythioxanthone, thioxanthone ammonium salt, 3-[3,4-dimethyl-9-oxo9H-thioxanthone-2-yl]oxy]-2-hydroxypropyl-N,N,N-trimethylammonium chloride, phlothioxanthone, etc.

[0126] Representative examples of the above naphthalene compounds include naphthalene, 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 2-p-chlorobenzyloxynaphthalene, 2-p-isopropylbenzyloxynaphthalene, 1,4-dimethoxynaphthalene, 1-ethoxy-4-methoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dipropoxynaphthalene, 1,4-dibutoxynaphthalene, 2-dodecyloxynaphthalene, 2-decanoyloxynaphthalene, and 2-myristo. Examples include, but are not limited to, yloxynaphthalene, 2-pt-butylbenzoyloxynaphthalene, 2-benzoyloxynaphthalene, 2-benzyloxy-3-N-(3-dodecyloxypropyl)carbamoylnaphthalene, 2-benzoyloxy-3-N-octylcarbamoylnaphthalene, 2-benzyloxy-3-dodecyloxycarbonylnaphthalene, 2-benzyloxy-3-pt-butylphenoxycarbonylnaphthalene, β-mercaptonaphthalene, etc.

[0127] Typical examples of the above anthracene compounds are those represented by the following general formula (4), but are not limited to these.

[0128] [ka] (In the formula, R2 represents a hydrogen atom or an alkyl group. The alkyl group is a linear or branched alkyl group having 1 to 20 carbon atoms. In the formula, R3 and R4 are the same or different, representing a hydrogen atom, an alkyl group, an alkoxy group, or an alkyloyloxy group. The alkyl group is a linear or branched alkyl group having 1 to 20 carbon atoms. The alkoxy group is represented by -O-R5, where R5 is a linear or branched alkyl group having 1 to 20 carbon atoms. The alkyloyloxy group is represented by -O-CO-R6, where R6 is a linear or branched alkyl group having 1 to 20 carbon atoms.)

[0129] Typical examples of the above anthracene compounds include, but are not limited to, anthracene, dimethylanthracene, 9-ethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-dibutoxyanthracene, 9-hydroxymethylanthracene, 9,10-diphenylanthracene, 9,10-bis(octanoyloxy)-anthracene, halogenated anthracene, 9,10-bis(phenylethynyl)anthracene, and 2-chloro-9,10-bis(phenylethynyl)anthracene.

[0130] Typical examples of the above anthraquinone compounds include, but are not limited to, anthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1,2-dihydroxyanthraquinone, 2-diethylanthraquinone, and 1,2-benzanthraquinone.

[0131] Typical examples of the above-mentioned benzoin compounds include, but are not limited to, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and 2-hydroxy-1-[4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]phenyl]-2-methylpropan-1-one.

[0132] Representative examples of the above coumarin compounds include, but are not limited to, coumarin, 7-hydroxy-4-methylcoumarin, 4-hydroxy-7-methylcoumarin, 3-(2-benzimidazolyl)-7-(diethylamino)coumarin, 3-(2-benzothiazolyl)-7-(diethylamino)coumarin, 7-diethylamino-4-methylcoumarin, 3-phenyl-7-aminocoumarin, 3-phenyl-7-(imino-1',3',5'-triazine-2'-diethylamino-4'-chloro)coumarin, 3-phenyl-7-naphthotriazolecoumarin, 7-(4'-chloro-6''-diethylamino-1',3',5'-triazine-4'-yl)amino-3-phenylcoumarin, and 3,3'-carbonyl-bis(5,7-dimethoxycarbonylcoumarin).

[0133] Component (D) is preferably at least one selected from the group consisting of benzophenone compounds, thioxanthone compounds, naphthalene compounds, and anthracene compounds, from the standpoint of excellent curing properties in the shielded area and deep within. Furthermore, for the same reasons as described above, component (D) is more preferably at least one selected from the group consisting of benzophenone, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, and 9,10-bis(octanoyloxy)-anthracene.

[0134] (Physical properties of photosensitizer (D)) The physical properties of component (D) are not particularly limited.

[0135] The content of component (D) in the above UV-curable resin composition is not particularly limited. However, from the viewpoint of excellent curability in shielded areas and deep areas, it is preferable that the content is 0.0001% by mass or more (more narrowly, greater than 0.0001% by mass) and 0.02% by mass or less (more narrowly, less than 0.02% by mass) on a solid content basis, and more preferably 0.0004% by mass or more (more narrowly, greater than 0.0004% by mass) and 0.009% by mass or less (more narrowly, less than 0.009% by mass) based on 100% by mass of the UV-curable resin composition.

[0136] (Polymerization inhibitor (E)) The ultraviolet-curable resin composition of this embodiment may contain a polymerization inhibitor (E) (hereinafter referred to as component (E)). Component (E) is not particularly limited and various known components can be used. Component (E) may be used alone or in combination of two or more types.

[0137] Typical examples of component (E) include, but are not limited to, hydroquinone, trimethylhydroquinone, p-methoxyphenol, phenothiazine, N-nitrosophenylhydroxylamine aluminum salt, and 2,6-di-tert-butyl-4-methylphenol.

[0138] Component (E) is preferably at least one selected from the group consisting of N-nitrosophenylhydroxylamine aluminum salt and phenothiazine.

[0139] The content of component (E) in the above UV-curable resin composition is not particularly limited, but is preferably 0.0001% by mass or more and 0.05% by mass or less (more narrowly, less than 0.05% by mass) based on solid content relative to 100% by mass of the composition.

[0140] (Reactive diluent) The UV-curable resin composition of this embodiment may contain a reactive diluent. The reactive diluent is a compound having UV-reactive functional groups such as carbon-carbon unsaturated bonds other than component (A). The reactive diluent may be used alone or in combination of two or more types.

[0141] Typical examples of the above-mentioned reactive diluents include (meth)acrylic acid, mono(meth)acrylate, styrene, α-methylstyrene, and ethyl carbitol acrylate, but are not limited to these.

[0142] Typical examples of the above-mentioned mono(meth)acrylates include, but are not limited to, the hydroxyl group-containing mono(meth)acrylates and alkyl(meth)acrylates.

[0143] Typical examples of the alkyl (meth)acrylates listed above include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, myristyl (meth)acrylate, pentadecyl (meth)acrylate, palmityl (meth)acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate, isopropyl (meth)acrylate, tert-butyl (meth)acrylate, and isobutyl (meth)acrylate. Examples include, but are not limited to, isopentyl (meth)acrylate, methylbutyl (meth)acrylate, isododecyl (meth)acrylate, isotridecyl (meth)acrylate, isomiristyl (meth)acrylate, isopentadecyl (meth)acrylate, isohexadecyl (meth)acrylate, isoheptadecyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, henicosyl (meth)acrylate, docosyl (meth)acrylate, tricosyl (meth)acrylate, tetracosyl (meth)acrylate, pentacosyl (meth)acrylate, hexacosyl (meth)acrylate, heptacosyl (meth)acrylate, and octacosyl (meth)acrylate.

[0144] In the above UV-curable resin composition, when a reactive diluent is used, the total content of component (A) and the reactive diluent in the composition is preferably 25% by mass or more (more narrowly, more than 25% by mass) and 80% by mass or less (more narrowly, less than 80% by mass) based on solid content, relative to 100% by mass of the composition.

[0145] In the above UV-curable resin composition, the content ratio of component (A) to the reactive diluent is not particularly limited. From the viewpoint of adjusting the crosslinking density, when the total of component (A) and the reactive diluent is 100% by mass, it is preferable that component (A) is 20% by mass or more (more narrowly, more than 20% by mass) and 100% by mass or less, and the reactive diluent is 0% by mass or more and 80% by mass or less (more narrowly, less than 80% by mass). Furthermore, considering the hardness and scratch resistance of the cured product, it is preferable that component (A) is 50% by mass or more (more narrowly, more than 50% by mass) and 95% by mass or less (more narrowly, less than 95% by mass), and the reactive diluent is 5% by mass or more (more narrowly, more than 5% by mass) and 50% by mass or less (more narrowly, less than 50% by mass).

[0146] (Photopolymerization initiator) The above UV-curable resin composition may optionally contain photopolymerization initiators other than component (C), provided that the effects of the present invention are not impaired. Two or more of these photopolymerization initiators may be used in combination. Typical examples of such photopolymerization initiators include, but are not limited to, 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]-phenyl}-2-methyl-propan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, etc.

[0147] The content of photopolymerization initiators other than component (C) in the above UV-curable resin composition is not particularly limited. From the viewpoint of the reaction progress of the (meth)acryloyl group, the content of the photopolymerization initiator is preferably 0.5 parts by mass or more and 15 parts by mass or less per 100 parts by mass of the composition, on a solid content basis.

[0148] (solvent) The above UV-curable resin composition may contain a solvent, taking into consideration the ease of application. Typical examples of solvents include, but are not limited to, methyl ethyl ketone, methyl isobutyl ketone, methyl acetate, ethyl acetate, butyl acetate, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, isobutyl alcohol, tert-butyl alcohol, diacetone alcohol, acetylacetone, toluene, xylene, n-hexane, cyclohexane, methylcyclohexane, n-heptane, isopropyl ether, methyl cellosolve, ethyl cellosolve, 1,4-dioxane, propylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, and propylene glycol monomethyl ether acetate. The diluent solvent may be used alone or in combination of two or more. Considering the surface smoothness of the cured film obtained from the composition, at least one solvent selected from the group consisting of glycol ethers, alcohols, and ketones is preferred.

[0149] The content of the solvent in the above-mentioned ultraviolet-curable resin composition is not particularly limited. When the composition contains a solvent, from the viewpoint of coating properties, it is preferable that the solvent content is in a range of 1% by mass or more and 60% by mass or less.

[0150] (Additives) The above UV-curable resin composition may optionally contain an additive other than the solvent, reactive diluent, or photopolymerization initiator, as long as it does not impair the effects of the present invention. The additive may be used alone or in combination of two or more. Typical examples of additives include, but are not limited to, antistatic agents, antioxidants, UV absorbers, light stabilizers, defoamers, surface modifiers, anti-fogging agents, hydrophilic agents, anti-fouling agents, pigments, metal oxide particle dispersions, organic particle dispersions, etc.

[0151] The content of the additive in the above UV-curable resin composition is not particularly limited. Preferably, the content of the additive is 0.05 parts by mass or more and 1 part by mass or less per 100 parts by mass of the composition, on a solid content basis.

[0152] [glue] The adhesive of this embodiment contains the above-mentioned ultraviolet-curable resin composition. Furthermore, the adhesive of this embodiment may optionally contain solvents and additives, provided that the effects of the present invention are not impaired. The solvents and additives may be used individually or in combination of two or more.

[0153] The solvents mentioned above are not particularly limited. Typical examples of the solvents include aromatic hydrocarbons such as benzene, toluene, ethylbenzene, n-propylbenzene, t-butylbenzene, o-xylene, m-xylene, p-xylene, tetralin, decalin, and aromatic naphtha; aliphatic hydrocarbons such as n-hexane, n-heptane, n-octane, isooctane, and n-decane; alicyclic hydrocarbons such as cyclohexane; esters such as ethyl acetate, n-butyl acetate, n-amyl acetate, 2-hydroxyethyl acetate, 2-butoxyethyl acetate, 3-methoxybutyl acetate, and methyl benzoate; acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, and methyl benzoate. Ketones such as chlorohexanone and methylcyclohexanone; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether; and alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, s-butyl alcohol, and t-butyl alcohol, but not limited to these.

[0154] The above-mentioned additives are not particularly limited. Typical examples of the above-mentioned additives include, but are not limited to, tackifiers, plasticizers, antioxidants, surface modifiers, surfactants, UV absorbers, antioxidants, light stabilizers, inorganic fillers, silane coupling agents, colloidal silica, defoamers, wetting agents, rust inhibitors, crystal nucleating agents, crystallization accelerators, etc.

[0155] The content of the additive in the above adhesive is not particularly limited. From the viewpoint of adjusting curability or curing inhibition, it is preferable that the content of the additive be 0.05 parts by mass or more and 1 part by mass or less per 100 parts by mass of the adhesive, on a solid content basis.

[0156] Because the adhesive of this embodiment exhibits excellent curing properties in light-shielding areas and deep areas, it is suitable as an adhesive used in shaded areas and narrow gaps, for example, as an adhesive used between a protective panel and a touch panel in an image display device, or as an adhesive used for joining various electronic components on an electronic circuit board.

[0157] [Sealant] The encapsulant of this embodiment contains the above-mentioned ultraviolet-curable resin composition. Furthermore, the encapsulant of this embodiment may contain additives as needed, as long as the effects of the present invention are not impaired. The additives may be used individually or in combination of two or more.

[0158] The above-mentioned encapsulant is not particularly limited. Typical examples of the above-mentioned encapsulant include, but are not limited to, ion scavengers, silane coupling agents, fluorine coupling agents, leveling agents, defoamers, antioxidants, surface lubricants, wetting and dispersing agents, stress relievers, flame retardants, colorants (such as carbon black), and diluents.

[0159] The content of the additive in the above-mentioned sealant is not particularly limited. From the viewpoint of adjusting curability or curing inhibition, it is preferable that the content of the additive is 0.1 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the sealant, on a solid content basis.

[0160] Because the encapsulant of this embodiment exhibits excellent curing properties in light-shielding areas and deep within, it can be applied to encapsulants used in parts with complex shapes that are difficult to expose to ultraviolet light, or to encapsulants where a shielding area exists in the operating environment. For example, the encapsulant of this embodiment is suitable as an encapsulant used in optical lens units, an encapsulant for leaded electronic components, and an underfill agent.

[0161] [Insulating protective agent] The insulating protective agent of this embodiment contains the above-mentioned ultraviolet-curable resin composition. The insulating protective agent of this embodiment can also be used as an insulating protective agent for electronic circuit boards. By coating the insulating protective agent of this embodiment onto an electronic circuit board and curing it, a cured film (cured product) with insulating and moisture-proof properties can be formed, thereby protecting the electronic circuit board from the external environment.

[0162] The insulating protective agent of this embodiment may include diluents and additives as needed, as long as they do not impair the effects of the present invention. Diluents and additives may be used individually or in combination of two or more.

[0163] Typical examples of the above-mentioned diluents include, but are not limited to, dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, ethyl acetate, γ-butyl lactone (γ-butyrolactone), acetone, methyl isobutyl ketone, ethyl methyl ketone, cyclohexanone, diisopropyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, dioxane, tetrahydrofuran, methanol, ethanol, n-propanol, benzene, toluene, xylene, dimethyl sulfoxide, and phenyl glycidyl ether.

[0164] The above additives are not particularly limited. Typical examples of the above additives include surfactants, adhesion improvers, defoamers, sensitizers other than component (D), fluorescent agents, etc., but are not limited to these.

[0165] The content of the additive in the above insulating protective agent is not particularly limited. Preferably, the content of the additive is 0.05 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the insulating protective agent, on a solid content basis.

[0166] Because the insulating protective agent of this embodiment exhibits excellent curing properties in light-shielding areas and deep areas, it can be a suitable insulating protective agent for electronic circuit boards where electronic components are mounted and shadowed areas and narrow gaps exist.

[0167] [Electronic circuit board] The electronic circuit board of this embodiment includes a cured product of the above-mentioned insulating protective agent. A typical example of the cured product is obtained by coating the electronic circuit board with the above-mentioned insulating protective agent and irradiating it with ultraviolet light. Typical examples of the electronic circuit board include, but are not limited to, rigid printed circuit boards and flexible printed circuit boards.

[0168] Typical examples of ultraviolet light sources used in curing reactions include xenon lamps, high-pressure mercury lamps, metal halide lamps, and LED lamps, but are not limited to these. From the viewpoint of energy saving and space saving, LED lamps are preferred as ultraviolet light sources. The light intensity, light source arrangement, transport speed, etc., can be adjusted as needed.

[0169] Typical coating methods include, but are not limited to, bar coating, Meyer bar coating, air knife coating, dispenser coating, spray coating, gravure printing, reverse gravure printing, offset printing, flexographic printing, screen printing, jet printing, dip coating, and curtain coating.

[0170] <Examples> The above-described embodiment will be explained in more detail below with reference to examples. However, the present invention and its embodiments are not limited to these examples. In the examples, "%" and "parts" mean "mass%" and "parts by mass" respectively unless otherwise specified.

[0171] [Preparation of UV-curable resin compositions] [Example 1] (A) 100 parts of trimethylolpropane triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Viscote #295") (hereinafter referred to as component (A1)), (B) 137 parts of pentaerythritol tetrakis (3-mercaptobutyrate) (manufactured by Showa Denko K.K., trade name "Karenz MT® PE1") (hereinafter referred to as component (B1)), (C) 0.2 parts of 2,4,6-trimethylbenzoyl diphenylphosphine oxide (manufactured by IGM Resins BV, trade name "Omnirad TPO H") (hereinafter referred to as component (C1)), (D) benzophenone (manufactured by IGM Resins BV, trade name "Omnirad BP 0.002 parts of "Flakes" (hereinafter referred to as component (D1)) and 0.005 parts of N-nitrosophenylhydroxylamine aluminum salt (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "Q-1301") as a polymerization inhibitor were blended according to the solid content ratio, and diluted with methyl ethyl ketone to prepare an ultraviolet-curable resin composition with a solid content of 50%.

[0172] [Examples 2-16 and Comparative Examples 1-6] In Example 1, an ultraviolet-curable resin composition was produced using the same procedure as in Example 1, except that the composition and amounts of components (A) to (D) were changed to those shown in Tables 1 and 2.

[0173] (Absorbance of photopolymerization initiator (C) at 385 nm) Component (C1) was mixed with acetonitrile to prepare a 500 ppm acetonitrile solution. The absorbance at 385 nm was measured using a spectrophotometer (Shimadzu Corporation, UV-Vis Spectrophotometer UV-2600) with a 10 mm path length two-sided transmission quartz cell (Shimadzu GLC Co., Ltd., rectangular cell). The same measurements were performed for components (C2) to (C3) and component (c1).

[0174] [Table 1]

[0175] [Table 2]

[0176] The amounts in Tables 1 and 2 are given as parts by mass, converted to solid content. The abbreviations in Tables 1 and 2 are as follows. Note that blank spaces in each table indicate that the corresponding ingredient is not included.

[0177] (A1): Trimethylolpropane triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., product name "Viscoat #295") (A2): 1,4-Cyclohexanedimethanol divinyl ether (manufactured by Nippon Carbide Industries Co., Ltd., trade name "CHDVE") (B1): Pentaerythritol tetrakis(3-mercaptobutyrate) (manufactured by Showa Denko K.K., product name "Karens MT(registered trademark) PE1") (B2): 1,3,5-Tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (manufactured by Showa Denko K.K., trade name "Kalens MT(registered trademark) NR1") (B3): 1,4-Bis(3-mercaptobutyryloxy)butane (manufactured by Showa Denko K.K., product name "Kalens MT(registered trademark) BD1") (B4): Pentaerythritol tetrakis(3-mercaptopropionate) (manufactured by SC Organic Chemicals Co., Ltd., trade name "PEMP") (C1): 2,4,6-Trimethylbenzoyldiphenylphosphine oxide (manufactured by IGM Resins BV, trade name "Omnirad TPO H", absorbance at 385 nm 0.76) (C2): Bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (manufactured by IGM Resins BV, trade name "Omnirad 819", absorbance 0.91 at 385 nm) (C3): 2-Benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one (manufactured by IGM Resins BV, trade name "Omnirad 369", absorbance 0.39 at 385 nm) (c1): 2-Methyl-1-[4-methylthio]phenyl]-2-morpholinopropan-1-one (manufactured by IGM Resins BV, trade name "Omnirad 907", absorbance 0.065 at 385 nm) (D1): Benzophenone (manufactured by IGM Resins BV, brand name "Omnirad BP Flakes") (D2): 2,4-Diethylthioxanthone (manufactured by Nippon Kayaku Co., Ltd., trade name "KAYACURE DETX-S") (D3): 2-Isopropylthioxanthone (manufactured by Nippon Kayaku Co., Ltd., trade name "LUNACURE 2-ITX") (D4): 9,10-Bis(octanoyloxy)-anthracene (manufactured by Kawasaki Chemical Industries, Ltd., product name "Anthracure® UVS-581")

[0178] (shadow hardening) A spacer was placed on an FRP substrate measuring 150 mm wide x 70 mm long x 2 mm thick (manufactured by Nippon Test Panel Co., Ltd., product name "FRP") (Figure 1). The UV-curable resin compositions of Examples 1-16 and Comparative Examples 1-6 were applied to the areas not covered by the spacer using a cylindrical glass rod, forming a film with a width of 25 mm x length of 70 mm x thickness of 400 μm (Figure 2). Next, a PET film measuring 70 mm wide x 100 mm long x 75 μm thick with a release layer was bonded to the composition with the release layer facing the UV-curable resin composition side, ensuring no air was trapped inside (Figure 3). Then, a light-shielding plate measuring 150 mm wide x 50 mm long x 2 mm thick was placed on top of the PET film (Figure 4). UV irradiation was then performed from the light-shielding plate side using a belt conveyor type UV-LED irradiation device (manufactured by GS Yuasa Corporation, UV-LED irradiation wavelength 385 nm) to an integrated light intensity of 10,000 mJ / cm². 2 The material was irradiated with ultraviolet light. Afterward, the light-shielding plate and PET film were peeled off from the edges to identify the boundary between the cured and uncured portions of the UV-curable resin composition (Figure 5). The distance from the edge of the light-shielding plate (reference line) to this boundary (d in Figure 6) was measured and defined as "curability in shaded areas (mm)". These measurements were performed three times, and the average value was calculated. The results are shown in Tables 1 and 2.

[0179] The shaded curing property of the UV-curable resin composition of Example 15 was evaluated using the above evaluation method, with a high-pressure mercury lamp (Multiply Co., Ltd. Belt conveyor type UV irradiation device 120 W / cm high-pressure mercury lamp) as the UV irradiation device, and an integrated light intensity of 10,000 mJ / cm². 2 Except for irradiation with ultraviolet light, the hardening properties in the shaded area were evaluated using the same procedure as the evaluation method described above. The results are shown in Table 2.

[0180] The UV-curable resin compositions of Examples 1 to 16 exhibit sufficient curability even in shielded areas and deep parts where UV light does not reach, due to their long shaded curing distance. On the other hand, the UV-curable resin compositions of Comparative Examples 1 to 6 exhibit insufficient curability or inability to confirm curability in shielded areas and deep parts where UV light does not reach, due to their short shaded curing distance.

[0181] Furthermore, in evaluating the curing properties in shaded areas, an opaque FRP substrate is used as the base material. The reason for this is that if a transparent substrate such as a glass plate is used, ultraviolet rays penetrate the interior of the substrate and reach the resin composition in the shaded areas, making it impossible to accurately evaluate the curing properties in shaded areas. With an opaque FRP substrate, ultraviolet rays do not easily penetrate the interior of the substrate, and as a result, the curing properties in shaded areas can be accurately evaluated.

[0182] As stated above, the disclosure of the embodiments and examples described above is provided for the purpose of explaining those embodiments and examples, and is not intended to limit the present invention. In addition, variations that fall within the scope of the present invention, including other combinations disclosed in the embodiments described above, are also included in the claims. [Industrial applicability]

[0183] The ultraviolet-curable resin composition of the present invention can be widely used in the fields of electrical or electronic equipment or optics by, for example, being used as an adhesive, a sealant, an insulating protective agent, or as an electronic circuit board containing a cured product of the insulating protective agent. [Explanation of Symbols]

[0184] 1: FRP base material (non-transparent material) 2: Spacer 3: Ultraviolet curable resin composition (uncured) 4: PET film 5: Light-shielding plate (non-transparent material) 6: Ultraviolet curable resin composition (cured) 7. Ultraviolet irradiation d: Distance from the edge of the light-shielding plate (reference line) to the boundary line between cured and uncured areas of the UV-curable resin composition (curing distance of the shaded area of ​​the UV-curable resin composition)

Claims

1. At least one compound (A) selected from the group consisting of a compound (a1) having at least two (meth)acryloyl groups in the molecule and a vinyl ether compound (a2) having at least two vinyl groups in the molecule, A compound (B) having at least two thiol groups in its molecule, A photopolymerization initiator (C) whose absorbance at a path length of 10 mm in a 500 ppm acetonitrile solution is 0.10 or higher at 385 nm, Photosensitizer (D), Includes, The content of compound (B) is 15% by mass or more and 70% by mass or less based on solid content, and The content of component (D) is 0.0001% by mass or more and 0.02% by mass or less, based on solid content, relative to 100% by mass of the resin composition. UV curable resin composition.

2. The above-mentioned component (B) is a compound having at least three thiol groups in its molecule. The ultraviolet-curable resin composition according to claim 1.

3. The (D) component is at least one selected from the group consisting of benzophenone compounds, thioxanthone compounds, naphthalene compounds, and anthracene compounds. The ultraviolet-curable resin composition according to claim 1.

4. The aforementioned component (C) is at least one compound selected from the group consisting of alkylphenone compounds and acylphosphine oxide compounds. The ultraviolet-curable resin composition according to claim 1.

5. Furthermore, it contains polymerization inhibitor (E), The ultraviolet-curable resin composition according to claim 1.

6. The (E) component is at least one selected from the group consisting of N-nitrosophenylhydroxylamine aluminum salt and phenothiazine. The ultraviolet-curable resin composition according to claim 5.

7. The UV-curable resin composition according to any one of claims 1 to 6 comprises glue.

8. The UV-curable resin composition according to any one of claims 1 to 6 comprises Sealant.

9. The UV-curable resin composition according to any one of claims 1 to 6 comprises Insulating protective agent.

10. A cured product of the insulating protective agent described in claim 9, Electronic circuit board.

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