Curable resin composition, cured product, adhesive, and adhesive film

Abstract

One purpose of the present invention is to provide a curable resin composition that has excellent fluid characteristics before being cured, excellent leach preventing ability when being semi-cured, and excellent heat resistance after being fully cured. Another purpose of the present invention is to provide: a cured product of said curable resin composition; and an adhesive agent and an adhesion film which are obtained by using said curable resin composition. This curable resin composition contains a curable resin, a photoinitiator, and a thermosetting agent. The thermosetting agent contains an imide oligomer.

Description

[Technical Field]

[0001] The present invention relates to a curable resin composition that exhibits excellent flow properties before curing, excellent leaching prevention after partial curing, and excellent heat resistance after full curing. The present invention also relates to a cured product of the curable resin composition, and to an adhesive and adhesive film made using the curable resin composition. [Background technology]

[0002] In recent years, the applications of flexible printed circuit boards (FPCs) have expanded to include automotive applications, and adhesives used in FPCs and the coverlay films that protect them require high-temperature and long-term heat resistance. Such adhesives utilize curable resin compositions made from curable resins such as epoxy resins, which exhibit low shrinkage and excellent adhesion, insulation, and chemical resistance. In particular, many curable resin compositions are used that yield good results in solder reflow tests for short-term heat resistance and thermal cycle tests for repeated heat resistance.

[0003] Adhesives used in the adhesive layer of flexible printed circuit boards need to have high fluidity to suppress voids during component mounting and to improve conformability to uneven surfaces. However, if the fluidity is too high, there is a problem that it will easily leach at the edges. Therefore, it is necessary to achieve both excellent fluidity and leaching prevention. As such adhesives, for example, Patent Documents 1 to 3 disclose curable resin compositions containing a thermosetting component such as epoxy resin and a thermoplastic resin such as acrylic resin, polyamide, polyester, or a flexible component such as acrylonitrile butadiene rubber. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2006-232984 [Patent Document 2] Japanese Patent Publication No. 2009-167396 [Patent Document 3] Japanese Patent Publication No. 2008-308686 [Patent Document 4] Japanese Patent Application Publication No. 5-306386 [Overview of the project] [Problems that the invention aims to solve]

[0005] With the recent expansion of applications in automotive and other fields, adhesives are required to have long-term heat resistance. However, adhesives using curable resin compositions disclosed in Patent Documents 1 to 3 have insufficient heat resistance. As an adhesive with excellent heat resistance, Patent Document 4 discloses an adhesive containing a soluble polyester, a phenoxy resin, and an imidosiloxane oligomer. However, the adhesive disclosed in Patent Document 4 had difficulty achieving both flow characteristics and leaching prevention.

[0006] The present invention aims to provide a curable resin composition that exhibits excellent flow properties before curing, excellent leaching prevention after partial curing, and excellent heat resistance after full curing. Furthermore, the present invention aims to provide a cured product of the curable resin composition, as well as an adhesive and adhesive film made using the curable resin composition. [Means for solving the problem]

[0007] The present invention relates to a curable resin composition comprising a curable resin, a photopolymerization initiator, and a thermosetting agent, wherein the thermosetting agent is a curable resin composition containing an imide oligomer. The present invention will be described in detail below.

[0008] The inventors investigated the use of a curable resin composition containing a curable resin and a thermosetting agent, further incorporating a photopolymerization initiator, using a curable resin that can be photocured (partially cured) by the photopolymerization initiator, and using an imide oligomer as the thermosetting agent. As a result, they found that a curable resin composition with excellent flow properties before curing, excellent leaching prevention after partial curing, and excellent heat resistance after full curing could be obtained, thus completing the present invention.

[0009] The curable resin composition of the present invention contains a curable resin. From the viewpoint of flow characteristics before curing, it is preferable that the curable resin contains a material that is liquid at 25°C.

[0010] The above-mentioned curable resin preferably contains a compound that can be photocured by a photopolymerization initiator described later when irradiated with light (photocurable resin) and a compound that can be thermocured by a thermosetting agent described later when heated (thermosetting resin). The above-mentioned photocurable resin and the above-mentioned thermosetting resin may be the same compound (photothermosetting resin), and even if the above-mentioned curable resin contains the photothermosetting resin, it may further contain a photocurable resin and / or a thermosetting resin.

[0011] The above-mentioned curable resin preferably contains radical polymerizable compounds that do not have epoxy groups, epoxy compounds that do not have radical polymerizable groups, and / or compounds that have epoxy groups and radical polymerizable groups. From the viewpoint of achieving more uniform curing and improving mechanical strength and reliability, the above-mentioned curable resin is even more preferably to contain radical polymerizable compounds that do not have epoxy groups, epoxy compounds that do not have radical polymerizable groups, and compounds that have epoxy groups and radical polymerizable groups.

[0012] As radical polymerizable compounds that do not have the epoxy group mentioned above, compounds having an ethylenically unsaturated double bond are preferred, and (meth)acrylic compounds are more preferred. In this specification, "(meth)acrylic" means acrylic or methacrylic, "(meth)acrylic compound" means a compound having a (meth)acryloyl group, and "(meth)acryloyl" means acryloyl or methacryloyl.

[0013] Examples of the (meth)acrylic compounds mentioned above include (meth)acrylic acid ester compounds, epoxy (meth)acrylates, and (meth)acrylamide compounds. In this specification, "(meth)acrylate" means acrylate or methacrylate, and "epoxy (meth)acrylate" refers to a compound obtained by reacting all epoxy groups in an epoxy compound with (meth)acrylic acid.

[0014] Among the above (meth)acrylic acid ester compounds, monofunctional ones include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, isomiristyl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, cyclohexyl Syl (meth)acrylate, isobornyl (meth)acrylate, bicyclopentenyl (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, methoxyethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, tetrahydrofurfuryl alcohol acrylic acid polymer ester, ethyl carbitol (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H,1H,5H-Octafluoropentyl (meth)acrylate, imido (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl hexahydrophthalate, 2-(meth)acryloyloxyethyl 2-hydroxypropyl phthalate, 2-(meth)acryloyloxyethyl phosphate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, 2-(((butylamino)carbonyl)oxy)ethyl (meth)acrylate, (3-propyloxetan-3-yl)methyl (meth)acrylate, (3-butyloxetan-3-yl)methyl (meth)acrylate, (3-ethyloxetan-3-yl)ethyl (meth)acrylate Examples include (3-ethyloxetan-3-yl)propyl (meth)acrylate, (3-ethyloxetan-3-yl)butyl (meth)acrylate, (3-ethyloxetan-3-yl)pentyl (meth)acrylate, (3-ethyloxetan-3-yl)hexyl (meth)acrylate, γ-butyrolactone (meth)acrylate, (2,2-dimethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-methyl-2-isobutyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, (2-cyclohexyl-1,3-dioxolan-4-yl)methyl (meth)acrylate, and cyclic trimethylolpropane formal acrylate.

[0015] Among the bifunctional (meth)acrylate compounds, examples include 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 2-n-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide adduct bisphenol A di(meth)acrylate, propylene oxide adduct bisphenol A di(meth)acrylate, ethylene oxide adduct bisphenol F di(meth)acrylate, dimethylol dicyclopentenyl di(meth)acrylate, ethylene oxide-modified isocyanuric acid di(meth)acrylate, 2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate, carbonate diol di(meth)acrylate, polyether diol di(meth)acrylate, polyester diol di(meth)acrylate, polycaprolactone diol di(meth)acrylate, polybutadiene diol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, and the like.

[0016] Among the above (meth)acrylic acid ester compounds, trifunctional or higher-functional ones include, for example, trimethylolpropane tri(meth)acrylate, ethylene oxide-added trimethylolpropane tri(meth)acrylate, propylene oxide-added trimethylolpropane tri(meth)acrylate, caprolactone-modified trimethylolpropane tri(meth)acrylate, ethylene oxide-added isocyanuric acid tri(meth)acrylate, glycerin tri(meth)acrylate, propylene oxide-added glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tris(meth)acryloyloxyethyl phosphate, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and the like.

[0017] Examples of the above epoxy(meth)acrylate include bisphenol A type epoxy(meth)acrylate, bisphenol F type epoxy(meth)acrylate, bisphenol E type epoxy(meth)acrylate, phenol novolac type epoxy(meth)acrylate, cresol novolac type epoxy(meth)acrylate, resorcinol type epoxy(meth)acrylate, and their caprolactone-modified products and the like.

[0018] Examples of the above (meth)acrylamide compound include N,N-dimethyl(meth)acrylamide, N-(meth)acryloylmorpholine, N-hydroxyethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, and the like.

[0019] Examples of epoxy compounds that do not have the above-mentioned radical polymerizable groups include bisphenol A type epoxy compounds, bisphenol E type epoxy compounds, bisphenol F type epoxy compounds, bisphenol S type epoxy compounds, bisphenol O type epoxy compounds, 2,2'-diallylbisphenol A type epoxy compounds, alicyclic epoxy compounds, hydrogenated bisphenol type epoxy compounds, propylene oxide-added bisphenol A type epoxy compounds, resorcinol type epoxy compounds, biphenyl type epoxy compounds, sulfide type epoxy compounds, diphenyl ether type epoxy compounds, dicyclopentadiene type epoxy compounds, naphthalene type epoxy compounds, phenol novolac type epoxy compounds, orthocresol novolac type epoxy compounds, dicyclopentadiene novolac type epoxy compounds, biphenyl novolac type epoxy compounds, naphthalenephenol novolac type epoxy compounds, glycidylamine type epoxy compounds, alkyl polyol type epoxy compounds, rubber-modified epoxy compounds, glycidyl ester compounds, and the like.

[0020] The above-mentioned curable resin preferably includes a compound having an epoxy group and a (meth)acryloyl group, as a compound having an epoxy group and a radical polymerizable group. Examples of compounds having the epoxy group and (meth)acryloyl group include partially (meth)acrylic modified epoxy compounds, glycidyl (meth)acrylate, and 4-hydroxybutyl acrylate glycidyl ether. In this specification, the term "partially (meth)acrylic-modified epoxy compound" refers to a compound having one or more epoxy groups and one or more (meth)acryloyl groups in one molecule, obtained by reacting a portion of the epoxy groups of an epoxy compound having two or more epoxy groups in one molecule with (meth)acrylic acid.

[0021] Examples of the above-mentioned partially (meth)acrylic modified epoxy compounds include partially (meth)acrylic modified bisphenol A type epoxy compounds, partially (meth)acrylic modified bisphenol F type epoxy compounds, partially (meth)acrylic modified bisphenol E type epoxy compounds, partially (meth)acrylic modified phenol novolac type epoxy compounds, partially (meth)acrylic modified cresol novolac type epoxy compounds, and partially (meth)acrylic modified resorcinol type epoxy compounds.

[0022] The curable resin composition of the present invention contains a photopolymerization initiator. Examples of the above-mentioned photopolymerization initiators include α-hydroxyketone compounds, α-hydroxyalkylphenone compounds, benzophenone compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, benzoin ether compounds, and thioxanthone compounds. Specifically, examples of the above photopolymerization initiators include 2-hydroxy-1-(4-isopropenylphenyl)-2-methyl-1-propanone oligomer, 1-hydroxycyclohexylphenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-((4-methylphenyl)methyl)-1-(4-(4-morpholinyl)phenyl)-1-butanone, 2,2-dimethoxy-1,2-diphenylethane-1-one, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 1-(4-(hydroxyethoxy)phenyl)-2-hydroxy-2-methyl-1-propan-1-one, and 1-(4-(phenyl Examples include thio)phenyl)-1,2-octanedione 2-(O-benzoyl oxime), 2,4,6-trimethylbenzoyldiphenylphosphine oxide, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl))propanone, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)phenoxy)phenyl)-2-methylpropan-1-one, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl)benzyl)phenyl)-2-methylpropan-1-one, and 1-(4-(4-benzoylphenylsulfanyl)phenyl)-2-methyl-2-(4-methylphenylsulfonyl)propan-1-one.

[0023] The preferred lower limit for the content of the above-mentioned photopolymerization initiator is 0.1 parts by weight and the preferred upper limit is 20 parts by weight per 100 parts by weight of the above-mentioned curable resin. When the content of the above-mentioned photopolymerization initiator is within this range, the resulting curable resin composition maintains excellent storage stability while exhibiting superior photocurability and superior leaching prevention after partial curing. A more preferred lower limit for the content of the above-mentioned photopolymerization initiator is 0.5 parts by weight and a more preferred upper limit is 10 parts by weight.

[0024] The curable resin composition of the present invention contains a thermosetting agent. The above-mentioned thermosetting agent contains an imide oligomer. By using the above-mentioned imide oligomer as the thermosetting agent, the curable resin composition of the present invention exhibits excellent heat resistance after curing.

[0025] The above imide oligomer preferably has an acid anhydride group or a phenolic hydroxyl group at the end of the main chain, and more preferably has an acid anhydride group or a phenolic hydroxyl group at both ends of the main chain.

[0026] The above imide oligomer preferably has a structure represented by the following formula (1-1) or formula (1-2), or by the following formula (2-1) or formula (2-2). By having a structure represented by the following formula (1-1) or formula (1-2), or by the following formula (2-1) or formula (2-2), the above imide oligomer exhibits superior reactivity and compatibility with the above curable resin.

[0027] [ka]

[0028] In formulas (1-1) and (1-2), A is an acid dianhydride residue, in formula (1-1), B is an aliphatic diamine residue or an aromatic diamine residue, and in formula (1-2), Ar is an optionally substituted divalent aromatic group.

[0029] [ka]

[0030] In formulas (2-1) and (2-2), A is an acid dianhydride residue, B is an aliphatic triamine residue or an aromatic triamine residue, and in formula (2-2), Ar is an optionally substituted divalent aromatic group.

[0031] The above acid dianhydride residue is preferably a tetravalent group represented by the following formula (3-1) or formula (3-2).

[0032] [ka]

[0033] In formulas (3-1) and (3-2), * represents a bond position, and in formula (3-1), Z is a bond, an oxygen atom, a carbonyl group, a sulfur atom, a sulfonyl group, a linear or branched divalent hydrocarbon group, or a divalent group having an aromatic ring. When Z is a hydrocarbon group, there may be an oxygen atom between the hydrocarbon group and each aromatic ring in formula (3-1), and when Z is a divalent group having an aromatic ring, there may be an oxygen atom between the divalent group having an aromatic ring and each aromatic ring in formula (3-1). The hydrogen atoms of the aromatic rings in formulas (3-1) and (3-2) may be substituted.

[0034] In formula (3-1) above, if Z is a linear or branched divalent hydrocarbon group, or a divalent group having an aromatic ring, these groups may be substituted. Examples of substituents when the above-mentioned linear or branched divalent hydrocarbon group, or the above-mentioned divalent group having an aromatic ring, is substituted include halogen atoms, linear or branched alkyl groups, linear or branched alkenyl groups, alicyclic groups, aryl groups, alkoxy groups, nitro groups, cyano groups, and the like.

[0035] Examples of acid dianhydrides from which the above-mentioned acid dianhydride residues originate include the acid dianhydride represented by formula (9) described later.

[0036] When B in formula (1-1) is the aliphatic diamine residue, or when B in formula (2-1) or formula (2-2) is the aliphatic triamine residue, the preferred lower limit for the number of carbon atoms in the aliphatic diamine residue and the aliphatic triamine residue is 4. Having 4 or more carbon atoms in the aliphatic diamine residue and the aliphatic triamine residue results in a curable resin composition that is superior in flexibility and processability before curing, and dielectric properties after curing. A more preferred lower limit for the number of carbon atoms in the aliphatic diamine residue and the aliphatic triamine residue is 5, and an even more preferred lower limit is 6. Furthermore, there is no particular preferred upper limit for the number of carbon atoms in the above-mentioned aliphatic diamine residue and aliphatic triamine residue, but the practical upper limit is 60.

[0037] Examples of aliphatic diamines from which the above-mentioned aliphatic diamine residues are derived include aliphatic diamines derived from dimer acids, linear or branched aliphatic diamines, aliphatic ether diamines, and aliphatic alicyclic diamines. Examples of aliphatic diamines derived from the above-mentioned dimer acids include dimer amines and hydrogenated dimer amines. Examples of the above-mentioned linear or branched aliphatic diamines include 1,4-butanediamine, 1,6-hexanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,14-tetradecanediamine, 1,16-hexadecanediamine, 1,18-octadecanediamine, 1,20-eicosanediamine, 2-methyl-1,8-octanediamine, 2-methyl-1,9-nonanediamine, and 2,7-dimethyl-1,8-octanediamine. Examples of the above-mentioned aliphatic ether diamines include 2,2'-oxybis(ethylamine), 3,3'-oxybis(propylamine), and 1,2-bis(2-aminoethoxy)ethane. Examples of the above-mentioned aliphatic alicyclic diamines include 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, cyclohexanediamine, methylcyclohexanediamine, and isophoronediamine. In particular, the aliphatic diamine residue is preferably an aliphatic diamine residue derived from the dimer acid.

[0038] Examples of aliphatic triamines from which the above-mentioned aliphatic triamine residues are derived include aliphatic triamines derived from trimer acids, linear or branched aliphatic triamines, aliphatic ether triamines, and aliphatic alicyclic triamines. Examples of aliphatic triamines derived from the above-mentioned trimer acids include trimer triamines and hydrogenated trimer triamines. Examples of the linear or branched aliphatic triamines mentioned above include 3,3'-diamino-N-methyldipropylamine, 3,3'-diaminodipropylamine, diethylenetriamine, bis(hexamethylene)triamine, and 2,2'-bis(methylamino)-N-methyldiethylamine. In particular, the aliphatic triamine residue is preferably an aliphatic triamine residue derived from the trimer acid.

[0039] Furthermore, a mixture of the dimer amine and trimer triamine may be used as the aliphatic diamine and / or aliphatic triamine.

[0040] Examples of commercially available aliphatic diamines and / or aliphatic triamines derived from the above-mentioned dimer acids and / or trimer acids include aliphatic diamines and / or aliphatic triamines manufactured by BASF and aliphatic diamines and / or aliphatic triamines manufactured by Croda. Examples of the aliphatic diamines and / or aliphatic triamines manufactured by BASF include Versamin 551 and Versamin 552. Examples of the aliphatic diamines and / or aliphatic triamines manufactured by Croda include Priamine 1071, Priamine 1073, Priamine 1074, and Priamine 1075.

[0041] When B in formula (1-1) above is the aromatic diamine residue, it is preferable that the aromatic diamine residue is a divalent group represented by the following formula (4-1) or formula (4-2).

[0042] [ka]

[0043] In formulas (4-1) and (4-2), * represents a bond position, and in formula (4-1), Y is a bond, an oxygen atom, a carbonyl group, a sulfur atom, a sulfonyl group, a linear or branched divalent hydrocarbon group, or a divalent group having an aromatic ring. When Y is a hydrocarbon group, there may be an oxygen atom between the hydrocarbon group and each aromatic ring in formula (4-1), and when Y is a divalent group having an aromatic ring, there may be an oxygen atom between the divalent group having an aromatic ring and each aromatic ring in formula (4-1). The hydrogen atoms of the aromatic rings in formulas (4-1) and (4-2) may be substituted.

[0044] If Y in formula (4-1) above is a linear or branched divalent hydrocarbon group, or a divalent group having an aromatic ring, these groups may be substituted. Examples of substituents when the above-mentioned linear or branched divalent hydrocarbon group, or the above-mentioned divalent group having an aromatic ring, is substituted include halogen atoms, linear or branched alkyl groups, linear or branched alkenyl groups, alicyclic groups, aryl groups, alkoxy groups, nitro groups, cyano groups, and the like.

[0045] Examples of aromatic diamines from which the above aromatic diamine residues originate include cases where the diamine represented by formula (10), described later, is an aromatic diamine.

[0046] Furthermore, if the above-mentioned imide oligomer has a siloxane skeleton in its structure, it may lower the glass transition temperature after curing, contaminate the adherend, and cause poor adhesion. Therefore, it is preferable that the imide oligomer does not have a siloxane skeleton in its structure.

[0047] The number-average molecular weight of the above imide oligomer is preferably 5000 or less. A number-average molecular weight of 5000 or less results in a cured product of the resulting curable resin composition exhibiting superior long-term heat resistance. A more preferable upper limit for the number-average molecular weight of the above imide oligomer is 4000, and an even more preferable upper limit is 3000. In particular, the number-average molecular weight of the above imide oligomer is preferably 900 to 5000 when it has the structure represented by formula (1-1) or formula (2-1), and preferably 550 to 4000 when it has the structure represented by formula (1-2) or formula (2-2). A more preferred lower limit for the number-average molecular weight when it has the structure represented by formula (1-1) or formula (2-1) is 950, and an even more preferred lower limit is 1000. A more preferred lower limit for the number-average molecular weight when it has the structure represented by formula (1-2) or formula (2-2) is 580, and an even more preferred lower limit is 600. In this specification, the "number-average molecular weight" is a value obtained by measuring it using gel permeation chromatography (GPC) with tetrahydrofuran as the solvent and converting it to polystyrene equivalent. Examples of columns used when measuring the number-average molecular weight in polystyrene equivalent by GPC include JAIGEL-2H-A (manufactured by Nippon Analytical Engineering Co., Ltd.).

[0048] The above-mentioned imide oligomer is preferably an imide oligomer represented by the following formula (5-1), (5-2), (5-3), (5-4), or (5-5), or an imide oligomer represented by the following formula (6-1), (6-2), (6-3), (6-4), (6-5), or (6-6).

[0049] [ka]

[0050] In formulas (5-1) to (5-5), A is the above-mentioned acid dianhydride residue, and in formulas (5-1), (5-3) to (5-5), A may be the same or different. In formulas (5-1) to (5-4), B is the above-mentioned aliphatic diamine residue or aromatic diamine residue, and in formulas (5-3) and (5-4), B may be the same or different. In formula (5-5), B is the above-mentioned aliphatic triamine residue or aromatic triamine residue. In formula (5-2), X is a hydrogen atom, a halogen atom, or an optionally substituted monovalent hydrocarbon group, and in formula (5-4), W is a hydrogen atom, a halogen atom, or an optionally substituted monovalent hydrocarbon group. In formulas (5-3) and (5-4), n is the number of repetitions.

[0051] [ka]

[0052] In formulas (6-1) to (6-6), A is the above-mentioned acid dianhydride residue, and A in formulas (6-1) to (6-6) may be the same or different. In formulas (6-1) to (6-6), R is a hydrogen atom, a halogen atom, or an optionally substituted monovalent hydrocarbon group, and R in formulas (6-1), (6-2), (6-4), and (6-6) may be the same or different. In formulas (6-3) and (6-5), W is a hydrogen atom, a halogen atom, or an optionally substituted monovalent hydrocarbon group. In formulas (6-2) to (6-4), B is the above-mentioned aliphatic diamine residue or aromatic diamine residue, and B in formulas (6-4) and (6-5) may be the same or different. In formula (6-6), B is either the above-mentioned aliphatic triamine residue or the above-mentioned aromatic triamine residue.

[0053] In the above formulas (5-1) to (5-5) and (6-1) to (6-6), A is preferably a tetravalent group represented by the following formula (7-1) or formula (7-2).

[0054] [ka]

[0055] In formulas (7-1) and (7-2), * represents a bond position, and in formula (7-1), Z is a bond, an oxygen atom, a carbonyl group, a sulfur atom, a sulfonyl group, a linear or branched divalent hydrocarbon group, or a divalent group having an aromatic ring. When Z is a hydrocarbon group, there may be an oxygen atom between the hydrocarbon group and each aromatic ring in formula (7-1), and when Z is a divalent group having an aromatic ring, there may be an oxygen atom between the divalent group having an aromatic ring and each aromatic ring in formula (7-1). The hydrogen atoms of the aromatic rings in formulas (7-1) and (7-2) may be substituted.

[0056] In the above formulas (5-1) to (5-4) and (6-2) to (6-5), B is preferably a divalent group represented by the following formula (8-1) or formula (8-2).

[0057] [ka]

[0058] In formulas (8-1) and (8-2), * represents a bond position, and in formula (8-1), Y is a bond, an oxygen atom, a carbonyl group, a sulfur atom, a sulfonyl group, a linear or branched divalent hydrocarbon group, or a divalent group having an aromatic ring. When Y is a hydrocarbon group, there may be an oxygen atom between the hydrocarbon group and each aromatic ring in formula (8-1), and when Y is a divalent group having an aromatic ring, there may be an oxygen atom between the divalent group having an aromatic ring and each aromatic ring in formula (8-1). The hydrogen atoms of the aromatic rings in formulas (8-1) and (8-2) may be substituted.

[0059] Methods for producing imide oligomers having the structure represented by formula (1-1) include, for example, reacting an acidic dianhydride represented by formula (9) with a diamine represented by formula (10). Alternatively, by using an aliphatic triamine or an aromatic triamine instead of the diamine represented by formula (10), imide oligomers having the structure represented by formula (2-1) can be produced.

[0060] [ka]

[0061] In formula (9), A is the same tetravalent group as A in formula (1-1) above.

[0062] [ka]

[0063] In formula (10), B is the same divalent group as B in formula (1-1) above, and R 1 ~R 4 Each of these is independently either a hydrogen atom or a monovalent hydrocarbon group.

[0064] A specific example of a method for reacting the acid dianhydride represented by formula (9) with the diamine represented by formula (10) is shown below. First, the diamine represented by formula (10) is dissolved in a solvent in which the amic acid oligomer obtained by the reaction is soluble (for example, N-methylpyrrolidone). The acid dianhydride represented by formula (9) is then added to the resulting solution and reacted to obtain an amic acid oligomer solution. Next, the solvent is removed by heating or reduced pressure, and the amic acid oligomer is further reacted by heating at approximately 200°C or higher for at least one hour. By adjusting the molar ratio of the acid dianhydride represented by formula (9) to the diamine represented by formula (10) and the imidation conditions, an imide oligomer having a desired number-average molecular weight and the structure represented by formula (1-1) at both ends can be obtained. Furthermore, by replacing a portion of the acid dianhydride represented by formula (9) with the acid anhydride represented by formula (11) below, an imide oligomer having a desired number-average molecular weight, having the structure represented by formula (1-1) above at one end, and the structure derived from the acid anhydride represented by formula (11) below at the other end can be obtained. In this case, the acid dianhydride represented by formula (9) and the acid anhydride represented by formula (11) below may be added simultaneously or separately. Furthermore, by replacing a portion of the diamine represented by formula (10) with the monoamine represented by formula (12) below, an imide oligomer having a desired number-average molecular weight, having the structure represented by formula (1-1) above at one end, and the structure derived from the monoamine represented by formula (12) below at the other end can be obtained. In this case, the diamine represented by formula (10) and the monoamine represented by formula (12) below may be added simultaneously or separately.

[0065] [ka]

[0066] In formula (11), Ar is an optionally substituted divalent aromatic group.

[0067] [ka]

[0068] In formula (12), Ar is an optionally substituted monovalent aromatic group, and R 5 and R 6 Each of these is independently either a hydrogen atom or a monovalent hydrocarbon group.

[0069] Methods for producing imide oligomers having the structure represented by formula (1-2) include, for example, a method of reacting an acid dianhydride represented by formula (9) with a phenolic hydroxyl group-containing monoamine represented by formula (13), or a method of reacting an acid dianhydride represented by formula (9) with a diamine represented by formula (10) with a phenolic hydroxyl group-containing monoamine represented by formula (13). Furthermore, by using an aliphatic triamine or an aromatic triamine instead of the diamine represented by formula (10), imide oligomers having the structure represented by formula (2-2) can be produced.

[0070] [ka]

[0071] In formula (13), Ar is an optionally substituted divalent aromatic group, and R 7 and R 8 Each of these is independently either a hydrogen atom or a monovalent hydrocarbon group.

[0072] A specific example of a method for reacting an acid dianhydride represented by formula (9) with a phenolic hydroxyl group-containing monoamine represented by formula (13) is shown below. First, the phenolic hydroxyl group-containing monoamine represented by formula (13) is dissolved in a solvent in which the amic acid oligomer obtained by the reaction is soluble (for example, N-methylpyrrolidone). The acid dianhydride represented by formula (9) is then added to the resulting solution and reacted to obtain an amic acid oligomer solution. Next, the solvent is removed by heating or reduced pressure, and the amic acid oligomer is further reacted by heating at approximately 200°C or higher for at least one hour. By adjusting the molar ratio of the acid dianhydride represented by formula (9) to the phenolic hydroxyl group-containing monoamine represented by formula (13) and the imidation conditions, an imide oligomer having a desired number-average molecular weight and the structure represented by formula (1-2) at both ends can be obtained. Furthermore, by replacing a portion of the phenolic hydroxyl group-containing monoamine represented by formula (13) with the monoamine represented by formula (12), an imide oligomer having a desired number-average molecular weight, having the structure represented by formula (1-2) at one end, and the structure derived from the monoamine represented by formula (12) at the other end can be obtained. In this case, the phenolic hydroxyl group-containing monoamine represented by formula (13) and the monoamine represented by formula (12) may be added simultaneously or separately.

[0073] A specific example of a method for reacting the acid dianhydride represented by formula (9) above with the diamine represented by formula (10) above with the phenolic hydroxyl group-containing monoamine represented by formula (13) above is shown below. First, the phenolic hydroxyl group-containing monoamine represented by formula (13) and the diamine represented by formula (10) are dissolved in a solvent in which the amic acid oligomer obtained by the reaction is soluble (for example, N-methylpyrrolidone). The acid dianhydride represented by formula (9) is then added to the resulting solution and reacted to obtain an amic acid oligomer solution. Next, the solvent is removed by heating or reduced pressure, and the amic acid oligomer is further reacted by heating at approximately 200°C or higher for at least one hour. By adjusting the molar ratio of the acid dianhydride represented by formula (9), the diamine represented by formula (10), and the phenolic hydroxyl group-containing monoamine represented by formula (13), and the imidation conditions, an imide oligomer having a desired number-average molecular weight and the structure represented by formula (1-2) at both ends can be obtained. Furthermore, by replacing a portion of the phenolic hydroxyl group-containing monoamine represented by formula (13) with the monoamine represented by formula (12), an imide oligomer having a desired number-average molecular weight, having the structure represented by formula (1-2) at one end, and the structure derived from the monoamine represented by formula (12) at the other end can be obtained. In this case, the phenolic hydroxyl group-containing monoamine represented by formula (13) and the monoamine represented by formula (12) may be added simultaneously or separately.

[0074] Examples of acid dianhydrides represented by formula (9) above include pyromellitic anhydride, 3,3'-oxydiphthalic anhydride, 3,4'-oxydiphthalic anhydride, 4,4'-oxydiphthalic anhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, acid dianhydride of 4,4'-bis(2,3-dicarboxylphenoxy)diphenyl ether, p-phenylenebis(trimellitate anhydride), and 2,3,3',4'-biphenyltetracarboxylic dianhydride. In particular, as the acid dianhydride used as a raw material for the above-mentioned imide oligomer has superior solubility and heat resistance, aromatic acid dianhydrides with a melting point of 240°C or lower are preferred, aromatic acid dianhydrides with a melting point of 220°C or lower are more preferred, aromatic acid dianhydrides with a melting point of 200°C or lower are even more preferred, and 3,4'-oxydiphthalic acid dianhydride (melting point 180°C) and 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic acid anhydride (melting point 190°C) are especially preferred. In this specification, the term "melting point" refers to the value measured as the endothermic peak temperature when the temperature is increased at 10°C / min using a differential scanning calorimeter. Examples of differential scanning calorimeters include the EXTEAR DSC6100 (manufactured by SII Nanotechnology Co., Ltd.).

[0075] Among the diamines represented by the above formula (10), aromatic diamines include, for example, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, bis(4-(4-aminophenoxy)phenyl)methane, and 2,2-bis(4-(4-aminophenoxy)phenyl)methane. Examples include s(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene, 1,4-bis(2-(4-aminophenyl)-2-propyl)benzene, 3,3'-diamino-4,4'-dihydroxyphenylmethane, 4,4'-diamino-3,3'-dihydroxyphenylmethane, 3,3'-diamino-4,4'-dihydroxyphenyl ether, bisaminophenylfluorene, bistorydinfluorene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diamino-3,3'-dihydroxyphenyl ether, 3,3'-diamino-4,4'-dihydroxybiphenyl, and 4,4'-diamino-2,2'-dihydroxybiphenyl.Among these, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene, 1,4-bis(2-(4-aminophenyl)-2-propyl)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, and 1,4-bis(4-aminophenoxy)benzene are preferred due to their excellent availability, and 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene, 1,4-bis(2-(4-aminophenyl)-2-propyl)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, and 1,4-bis(4-aminophenoxy)benzene are even more preferred due to their excellent solubility and heat resistance.

[0076] Examples of acid anhydrides represented by the above formula (11) include phthalic anhydride, 3-methylphthalic anhydride, 4-methylphthalic anhydride, 1,2-naphthalic anhydride, 2,3-naphthalic anhydride, 1,8-naphthalic anhydride, 2,3-anthracene dicarboxylate anhydride, 4-tert-butylphthalic anhydride, 4-ethynylphthalic anhydride, 4-phenylethynylphthalic anhydride, 4-fluorophthalic anhydride, 4-chlorophthalic anhydride, 4-bromophthalic anhydride, and 3,4-dichlorophthalic anhydride.

[0077] Examples of monoamines represented by the above formula (12) include aniline, o-toluidine, m-toluidine, p-toluidine, 2,4-dimethylaniline, 3,4-dimethylaniline, 3,5-dimethylaniline, 2-tert-butylaniline, 3-tert-butylaniline, 4-tert-butylaniline, 1-naphthylamine, 2-naphthylamine, 1-aminoanthracene, 2-aminoanthracene, 9-aminoanthracene, 1-aminopyrene, 3-chloroaniline, o-anisidine, m-anisidine, p-anisidine, 1-amino-2-methylnaphthalene, 2,3-dimethylaniline, 2,4-dimethylaniline, 2,5-dimethylaniline, 3,4-dimethylaniline, 4-ethylaniline, 4-ethynylaniline, 4-isopropylaniline, 4-(methylthio)aniline, and N,N-dimethyl-1,4-phenylenediamine.

[0078] Examples of phenolic hydroxyl group-containing monoamines represented by the above formula (13) include 3-aminophenol, 4-aminophenol, 4-amino-o-cresol, 5-amino-o-cresol, 4-amino-2,3-xylenol, 4-amino-2,5-xylenol, 4-amino-2,6-xylenol, 4-amino-1-naphthol, 5-amino-2-naphthol, 6-amino-1-naphthol, and 4-amino-2,6-diphenylphenol. Among these, 4-amino-o-cresol and 5-amino-o-cresol are preferred because they have excellent availability and storage stability, and a high glass transition temperature can be obtained after curing.

[0079] When the above imide oligomer is produced by the manufacturing method described above, the imide oligomer is obtained as part of a mixture (imide oligomer composition) of multiple imide oligomers having the structure represented by formula (1-1) or multiple imide oligomers having the structure represented by formula (1-2) and each raw material. When an aliphatic triamine or aromatic triamine is used instead of the diamine represented by formula (10), the imide oligomer is obtained as part of a mixture (imide oligomer composition) of multiple imide oligomers having the structure represented by formula (2-1) or multiple imide oligomers having the structure represented by formula (2-2) and each raw material. Because the imidization rate of the imide oligomer composition is 70% or more, when used as a curing agent, it is possible to obtain a cured product that has superior mechanical strength at high temperatures and long-term heat resistance. The preferred lower limit for the imidation rate of the above imide oligomer composition is 75%, and the more preferred lower limit is 80%. There is no particular preferred upper limit for the imidation rate of the above imide oligomer composition, but the practical upper limit is 98%. The above "imidization rate" was measured using the total internal reflection (ATR) method with a Fourier transform infrared spectrophotometer (FT-IR), and the value derived from the carbonyl group of amic acid was 1660 cm⁻¹. -1 The peak absorbance area in the vicinity can be derived using the following formula. An example of the above Fourier transform infrared spectrophotometer is the UMA600 (manufactured by Agilent Technologies). In the following formula, "peak absorbance area of ​​amic acid oligomer" refers to the absorbance area of ​​the amic acid oligomer obtained by reacting an acidic dianhydride with a diamine or a phenolic hydroxyl group-containing monoamine, and then removing the solvent by evaporation or the like without performing an imidization step. Imidization rate (%) = 100 × (1 - (Peak absorbance area after imidization) / (Peak absorbance area of ​​amic acid oligomer))

[0080] From the viewpoint of solubility in a curable resin composition, it is preferable that the above imide oligomer composition dissolves in 3 g or more of tetrahydrofuran at 25°C.

[0081] The preferred lower limit for the content of the imide oligomer in the total of 100 parts by weight of the above curable resin and the above thermosetting agent (and further curing accelerator if it contains the curing accelerator described later) is 20 parts by weight, and the preferred upper limit is 80 parts by weight. Having the imide oligomer content within this range results in a curable resin composition that exhibits superior flexibility and processability before curing, and superior heat resistance after curing. A more preferred lower limit for the imide oligomer content is 25 parts by weight, and a more preferred upper limit is 75 parts by weight. Furthermore, if the imido oligomer according to the present invention is included in the above-described imido oligomer composition, the content of the above-described imido oligomer means the content of the imido oligomer composition (or, if other imido oligomers are used in combination, the total content of the imido oligomer composition and the other imido oligomers).

[0082] The curable resin composition of the present invention preferably contains a curing accelerator. By including the curing accelerator, the curing time can be shortened and productivity can be improved.

[0083] Examples of the curing accelerators mentioned above include imidazole-based curing accelerators, tertiary amine-based curing accelerators, phosphine-based curing accelerators, phosphorus-based curing accelerators, photobase generators, and sulfonium salt-based curing accelerators. Among these, imidazole-based curing accelerators are preferred due to their excellent storage stability.

[0084] The preferred lower limit for the content of the curing accelerator is 0.01 parts by weight and the preferred upper limit is 10 parts by weight, relative to 100 parts by weight of the total of the curable resin, thermosetting agent, and curing accelerator. Having the curing accelerator content within this range provides superior effectiveness in shortening the curing time while maintaining excellent adhesion. A more preferred lower limit for the curing accelerator content is 0.05 parts by weight and a more preferred upper limit is 5 parts by weight.

[0085] The curable resin composition of the present invention may contain an inorganic filler, to the extent that it does not hinder the objectives of the present invention.

[0086] The inorganic filler is preferably at least one of silica and barium sulfate. By including at least one of silica and barium sulfate as the inorganic filler, the curable resin composition of the present invention exhibits superior reflow resistance, plating resistance, and processability.

[0087] Examples of inorganic fillers other than the silica and barium sulfate mentioned above include alumina, aluminum nitride, boron nitride, silicon nitride, glass powder, glass frit, glass fiber, carbon fiber, and inorganic ion exchangers.

[0088] As the inorganic filler mentioned above, those with an average particle size of 50 nm or more and less than 4 μm are preferably used.

[0089] The preferred upper limit for the inorganic filler content is 200 parts by weight per 100 parts by weight of the total of the curable resin and the thermosetting agent (and the curing accelerator if one is included). This range of inorganic filler content allows the resulting cured resin composition to maintain excellent tackiness while exhibiting superior reflow resistance and plating resistance. A more preferred upper limit for the inorganic filler content is 150 parts by weight.

[0090] The curable resin composition of the present invention preferably contains a flow modifier for purposes such as improving quick wettability and shape retention on the adherend. Examples of the flow modifiers mentioned above include fumed silica such as Aerosil and layered silicates. Furthermore, as the flow modifier mentioned above, one with an average particle diameter of less than 100 nm is preferably used.

[0091] The content of the above-mentioned flow modifier is preferably 0.1 parts by weight and preferably 50 parts by weight per 100 parts by weight of the total of the above-mentioned curable resin and the above-mentioned thermosetting agent (and the above-mentioned curing accelerator if one is included). Having the content of the above-mentioned flow modifier within this range results in superior effects such as improved quick wettability and shape retention on the adherend. A more preferable lower limit for the content of the above-mentioned flow modifier is 0.5 parts by weight and a more preferable upper limit is 30 parts by weight.

[0092] The curable resin composition of the present invention may contain organic fillers for purposes such as stress relaxation and toughness enhancement. Examples of the above-mentioned organic fillers include silicone rubber particles, acrylic rubber particles, urethane rubber particles, polyamide particles, polyamide-imide particles, polyimide particles, benzoguanamine particles, and core-shell particles thereof. Among these, polyamide particles, polyamide-imide particles, and polyimide particles are preferred.

[0093] The preferred upper limit for the content of the above-mentioned organic filler is 300 parts by weight per 100 parts by weight of the total of the above-mentioned curable resin and the above-mentioned thermosetting agent (and the above-mentioned curing accelerator if it is included). By keeping the content of the above-mentioned organic filler within this range, the resulting cured product will have superior toughness and other properties while maintaining excellent adhesion. A more preferred upper limit for the content of the above-mentioned organic filler is 200 parts by weight.

[0094] The curable resin composition of the present invention preferably contains a polymer compound to the extent that it does not hinder the objective of the present invention. The polymer compound plays a role as a film-forming component, and the inclusion of the polymer compound results in a curable resin composition with superior leaching resistance.

[0095] The preferred lower limit for the number average molecular weight of the above polymer compound is 3,000, and the preferred upper limit is 100,000. Having the number average molecular weight of the above polymer compound within this range results in a curable resin composition that exhibits superior flexibility and processability before curing, and superior heat resistance after curing. A more preferred lower limit for the number average molecular weight of the above polymer compound is 5,000, and a more preferred upper limit is 80,000.

[0096] Examples of the above polymer compounds include polyimide, phenoxy resin, polyamide, polyamideimide, polymaleimide, cyanate resin, benzoxazine resin, acrylic resin, urethane resin, and polyester. Among these, polyimide, polyamide, polyamideimide, and polymaleimide are preferred from the viewpoint of heat resistance, with polyimide being more preferred. The above polymer compounds may be used individually or in combination of two or more types.

[0097] The content of the above polymer compound is preferably 1 part by weight and preferably 40 parts by weight per 100 parts by weight of the total of the above curable resin and the above thermosetting agent (and the above curing accelerator if one is included). Having the content of the above polymer compound within this range results in a cured product of the resulting curable resin composition having superior heat resistance. A more preferable lower limit for the content of the above polymer compound is 5 parts by weight and a more preferable upper limit is 30 parts by weight.

[0098] The curable resin composition of the present invention may contain a flame retardant to the extent that it does not hinder the objectives of the present invention. Examples of the above-mentioned flame retardants include metal hydrates such as boehmite-type aluminum hydroxide, aluminum hydroxide, and magnesium hydroxide, as well as halogen compounds, phosphorus compounds, and nitrogen compounds. Among these, boehmite-type aluminum hydroxide is preferred.

[0099] The preferred upper limit for the amount of the above-mentioned flame retardant is 200 parts by weight per 100 parts by weight of the total of the above-mentioned curable resin and the above-mentioned thermosetting agent (and the above-mentioned curing accelerator if it is included). When the amount of the above-mentioned flame retardant is within this range, the resulting curable resin composition will have excellent flame retardancy while maintaining excellent adhesion and other properties. A more preferred upper limit for the amount of the above-mentioned flame retardant is 150 parts by weight.

[0100] The above-mentioned curable resin composition may contain a solvent from the viewpoint of coating properties, etc. As for the solvents mentioned above, solvents with a boiling point of less than 200°C are preferred from the viewpoint of coating properties and storage stability. Examples of solvents with a boiling point below 200°C include alcohol-based solvents, ketone-based solvents, ester-based solvents, hydrocarbon-based solvents, halogen-based solvents, ether-based solvents, and nitrogen-containing solvents. Examples of the alcohol-based solvents mentioned above include methanol, ethanol, isopropyl alcohol, n-propyl alcohol, isobutyl alcohol, n-butyl alcohol, tertiary butyl alcohol, and 2-ethylhexanol. Examples of the ketone-based solvents mentioned above include acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl propyl ketone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, and diacetone alcohol. Examples of the ester-based solvents mentioned above include methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, methoxybutyl acetate, amyl acetate, n-propyl acetate, isopropyl acetate, methyl lactate, ethyl lactate, and butyl lactate. Examples of the hydrocarbon solvents mentioned above include benzene, toluene, xylene, n-hexane, isohexane, cyclohexane, methylcyclohexane, ethylcyclohexane, isooctane, n-decane, and n-heptane. Examples of the halogenated solvents mentioned above include dichloromethane, chloroform, and trichloroethylene. Examples of the ether-based solvents mentioned above include diethyl ether, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, diisopropyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, 3-methoxy-3-methyl-1-butanol, ethylene glycol monotertiary butyl ether, propylene glycol monomethyl ether propionate, 3-methoxybutanol, diethylene glycol dimethyl ether, anisole, and 4-methylanisole. Examples of the nitrogen-containing solvents mentioned above include acetonitrile, N,N-dimethylformamide, and N,N-dimethylacetamide. In particular, from the viewpoint of handling ease and solubility of imide oligomers, at least one selected from the group consisting of ketone solvents with a boiling point of 60°C or higher and less than 200°C, ester solvents with a boiling point of 60°C or higher and less than 200°C, and ether solvents with a boiling point of 60°C or higher and less than 200°C is preferred. Examples of such solvents include methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, isobutyl acetate, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, cyclohexanone, methylcyclohexanone, diethylene glycol dimethyl ether, and anisole. The above "boiling point" refers to the value measured under conditions of 101 kPa, or the value converted to 101 kPa using a boiling point conversion chart or similar.

[0101] The preferred lower limit for the content of the solvent in 100 parts by weight of the curable resin composition containing the above solvent is 20 parts by weight, and the preferred upper limit is 90 parts by weight. Having the solvent content within this range results in a curable resin composition with superior coating properties. A more preferred lower limit for the solvent content is 30 parts by weight, and a more preferred upper limit is 80 parts by weight.

[0102] The curable resin composition of the present invention may contain a reactive diluent to the extent that it does not impede the objectives of the present invention. From the viewpoint of adhesion reliability, as the reactive diluent, a reactive diluent having two or more reactive functional groups in one molecule is preferable.

[0103] The curable resin composition of the present invention may further contain additives such as a coupling agent, a dispersant, a storage stabilizer, a bleeding inhibitor, a fluxing agent, a leveling agent and the like.

[0104] Examples of the method for producing the curable resin composition of the present invention include a method of mixing a curable resin, a photopolymerization initiator, a thermosetting agent, and a curing accelerator added as necessary using a mixer. Examples of the mixer include a homodisper, a universal mixer, a Banbury mixer, a kneader, and the like.

[0105] The curable resin composition of the present invention preferably has a gel fraction of 5% or more and less than 90% after irradiation with ultraviolet rays of 2000 mJ / cm 2 . When the gel fraction after irradiation with ultraviolet rays of 2000 mJ / cm 2 is within this range, the leaching prevention property after semi-curing becomes more excellent. The more preferable lower limit of the gel fraction after irradiation with ultraviolet rays of 2000 mJ / cm 2 is 8%, and the more preferable upper limit is 80%. By adjusting the types and contents of the photocurable resin and the photothermosetting resin contained in the curable resin, or the types and contents of the photopolymerization initiator, it becomes easy to adjust the gel fraction after irradiation with ultraviolet rays of 2000 mJ / cm 2 to the above range. Also, the curable resin composition of the present invention preferably has a gel fraction of 90% or more after heating at 190°C for 1 hour. When the gel fraction after heating at 190°C for 1 hour is 90% or more, the heat resistance and adhesiveness after curing become more excellent. The more preferable lower limit of the gel fraction after heating at 190°C for 1 hour is 92%. By adjusting the types and contents of the thermosetting resin and the photothermosetting resin contained in the curable resin, or the types and contents of the thermosetting agent and the curing accelerator, it becomes easy to adjust the gel fraction after heating at 190°C for 1 hour to the above range. The "gel fraction" mentioned above refers to the percentage of the weight of undissolved material obtained after drying, relative to the initial weight of the curable resin composition. This is achieved by impregnating a partially cured or heat-cured curable resin composition with a solvent having sufficient solubility to dissolve the composition, stirring for 24 hours or more, filtering through a mesh, and then drying at 110°C for 1 hour, as shown in the formula below. For example, tetrahydrofuran can be used as the solvent. Gel fraction (%) = 100 × W2 / W1 (W1: Initial weight of the curable resin composition, W2: Weight of the undissolved material obtained after drying)

[0106] The curable resin composition of the present invention has a preferred lower limit for the 5% weight loss temperature of the cured product obtained by heating at 190°C for 1 hour, which is 350°C or higher. Because the 5% weight loss temperature of the cured product is 350°C or higher, the curable resin composition of the present invention has excellent heat resistance after curing and can be suitably used as a heat-resistant adhesive for automotive applications and the like. A more preferred lower limit for the 5% weight loss temperature of the cured product is 360°C, and an even more preferred lower limit is 370°C. Furthermore, there is no particular preferred upper limit for the 5% weight loss temperature of the cured product, but the practical upper limit is 450°C. The above 5% weight loss temperature can be derived by performing thermogravimetric measurements using a thermogravimetric analyzer under heating conditions from 30°C to 500°C at a heating rate of 10°C / min. Examples of such thermogravimetric analyzers include the TG / DTA6200 (manufactured by Hitachi High-Tech Science Corporation).

[0107] The curable resin composition of the present invention can be used in a wide range of applications, but is particularly suitable for electronic materials applications where high heat resistance is required. For example, it can be used in applications such as aerospace and automotive electrical control units (ECUs), and as a die attach agent in power devices using SiC and GaN. It can also be used, for example, as an adhesive for power overlay packages, a encapsulant, an adhesive for flexible printed circuit boards or coverlay films, copper-clad laminates, semiconductor bonding adhesives, interlayer insulating films, prepregs, LED encapsulants, and structural material adhesives. Among these, it is particularly suitable for bonding flexible printed circuit boards or coverlay films.

[0108] The cured product of the curable resin composition of the present invention is also one of the present inventions. An adhesive made using the curable resin composition of the present invention is also one of the present inventions. An adhesive film can be obtained by coating the adhesive of the present invention onto a film and then drying it. An adhesive film made using the adhesive of the present invention is also one of the present inventions. [Effects of the Invention]

[0109] According to the present invention, it is possible to provide a curable resin composition that has excellent flow properties before curing, excellent leaching prevention after partial curing, and excellent heat resistance after full curing. Furthermore, according to the present invention, it is possible to provide a cured product of the curable resin composition, as well as an adhesive and adhesive film made using the curable resin composition. [Modes for carrying out the invention]

[0110] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0111] (Synthesis Example 1 (Preparation of Imido Oligomer Composition A)) 104 parts by weight of 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic anhydride (manufactured by Tokyo Chemical Industries, Ltd.) was dissolved in 300 parts by weight of N-methylpyrrolidone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., "NMP"). To the resulting solution, 29.2 parts by weight of 1,3-bis(3-aminophenoxy)benzene (manufactured by Mitsui Chemicals Fine Chemicals, Ltd., "APB-N") was added to a solution diluted with 100 parts by weight of N-methylpyrrolidone, and the mixture was stirred at 25°C for 2 hours to obtain an amic acid oligomer solution. After removing N-methylpyrrolidone under reduced pressure from the obtained amic acid oligomer solution, the mixture was heated at 300°C for 2 hours to obtain imide oligomer composition A (imidization rate 95%). 1 ¹H-NMR, GPC, and FT-IR analysis confirmed that imide oligomer composition A contains an imide oligomer having the structure represented by formula (5-1) or (5-3) above (A is a 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic anhydride residue, and B is a 1,3-bis(3-aminophenoxy)benzene residue). The number-average molecular weight of imide oligomer composition A was 2100.

[0112] (Synthesis Example 2 (Preparation of Imido Oligomer Composition B)) 43.6 parts by weight of 3-aminophenol (manufactured by Tokyo Chemical Industry Co., Ltd.) was dissolved in 400 parts by weight of N-methylpyrrolidone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., "NMP"). 34.4 parts by weight of 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic anhydride was added to the resulting solution and the mixture was stirred at 25°C for 2 hours to obtain an amic acid oligomer solution. After removing N-methylpyrrolidone from the obtained amic acid oligomer solution under reduced pressure, the mixture was heated at 300°C for 2 hours to obtain imide oligomer composition B (imidization rate 95%). 1 ¹H-NMR, GPC, and FT-IR analysis confirmed that imide oligomer composition B contains an imide oligomer having the structure represented by formula (6-1) above (A is a 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic anhydride residue, and R is a hydrogen atom). The number-average molecular weight of imide oligomer composition B was 700.

[0113] (Preparation of Synthesis Example 3 (Polyimide Resin Solution A)) In a reaction vessel equipped with a stirrer, a water divider, and a nitrogen gas inlet tube, 54.6 parts by weight of 4,4'-(4,4'-isopropylidene diphenoxy)diphthalic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) and 200 parts by weight of cyclohexanone were charged and dissolved. To the resulting solution, a mixed solution of 56.1 parts by weight of the dimeramine Priamine 1074 (manufactured by Croda) and 55.0 parts by weight of cyclohexanone was added dropwise, and the imidation reaction was carried out at 150°C for 8 hours to obtain polyimide resin solution A. The solid content concentration of the obtained polyimide resin solution A was 30% by weight, and the number-average molecular weight of the polyimide resin was 25,000.

[0114] (Examples 1-6, Comparative Examples 1 and 2) According to the mixing ratios listed in Table 1, each material was stirred and mixed to prepare the curable resin compositions for Examples 1-6 and Comparative Examples 1 and 2.

[0115] <Rating> The following evaluations were performed on each curable resin composition obtained in the examples and comparative examples. The results are shown in Table 1.

[0116] (Gel fraction) Each curable resin composition obtained in the examples and comparative examples was coated onto a base PET film to a thickness of approximately 20 μm and dried to produce a curable resin composition film on the base PET film. Each of the resulting curable resin composition films was subjected to a 2000 mJ / cm³ treatment. 2 A semi-cured film was obtained by irradiating it with ultraviolet light. The obtained semi-cured film was impregnated with tetrahydrofuran, stirred for more than 24 hours, filtered through a mesh, and dried at 110°C for 1 hour, and the gel fraction was derived using the formula described above. Furthermore, a cured product was prepared by heating the obtained semi-cured film at 190°C for 1 hour. The obtained cured product was impregnated with tetrahydrofuran, stirred for more than 24 hours, filtered through a mesh, and dried at 110°C for 1 hour, and the gel fraction was derived using the formula described above.

[0117] (5% weight loss temperature) Each curable resin composition obtained in the examples and comparative examples was coated onto a base PET film to a thickness of approximately 20 μm and dried to produce a curable resin composition film on the base PET film. Each of the resulting curable resin composition films was subjected to a 2000 mJ / cm³ treatment. 2 A cured product was prepared by irradiating it with ultraviolet light and then heating it at 190°C for 1 hour. The 5% weight loss temperature of the obtained cured product was measured using a thermogravimetric analyzer (Hitachi High-Tech Science Corporation, "TG / DTA6200") in a temperature range of 30°C to 500°C under a heating rate of 10°C / min.

[0118] (Implementability (leachability and embeddability)) Each curable resin composition obtained in the examples and comparative examples was coated onto a 25 μm thick polyimide film (Toray DuPont, "Kapton 100H") to a thickness of 20 μm, thereby creating a polyimide film containing the curable resin composition. After making 5 mmφ holes in the obtained curable resin composition film, a flexible copper-clad laminate having a copper wiring pattern with L / S = 100 μm / 100 μm was temporarily attached using a laminator set to 80°C. 2000 mJ / cm² was applied from the polyimide film side. 2 The curable resin composition around the opening was partially cured by irradiation with ultraviolet light. Then, it was heat-cured for 1 hour at 160°C and 1.0 MPa using a hot press. The length of resin that seeped into the inside of the hole was measured as the leaching amount. Leaching prevention was evaluated as follows: "○" if there was no leaching (leaching amount was less than 0.2 mm), "△" if the leaching amount was between 0.2 mm and 0.5 mm, and "×" if the leaching amount exceeded 0.5 mm. Furthermore, after hot pressing, the samples were cross-sectionally polished and observed under an optical microscope. The embedding ability was evaluated by marking "○" if no voids were found between the copper wiring patterns and "×" if voids were found.

[0119] [Table 1] [Industrial applicability]

[0120] According to the present invention, it is possible to provide a curable resin composition that has excellent flow properties before curing, excellent leaching prevention after partial curing, and excellent heat resistance after full curing. Furthermore, according to the present invention, it is possible to provide a cured product of the curable resin composition, as well as an adhesive and adhesive film made using the curable resin composition.

Claims

1. It contains a curable resin, a photopolymerization initiator, and a thermosetting agent. The curable resin includes radical polymerizable compounds that do not have epoxy groups and epoxy compounds that do not have radical polymerizable groups, and / or compounds that have epoxy groups and radical polymerizable groups. The aforementioned thermosetting agent comprises an imide oligomer, The imide oligomer has an acid anhydride group or a phenolic hydroxyl group at the end of its main chain. A curable resin composition characterized by the following features.

2. The curable resin composition according to claim 1, wherein the curable resin comprises a compound having an epoxy group and a (meth)acryloyl group.

3. 2000 mJ / cm ２ The curable resin composition according to claim 1 or 2, wherein the gel fraction after irradiation with ultraviolet light is 5% or more and less than 90%, and the gel fraction after irradiation with ultraviolet light at 2000 mJ / cm² and heating at 190°C for 1 hour is 90% or more.

4. The curable resin composition according to claim 1, 2, or 3, wherein the temperature of the cured product obtained by irradiating with ultraviolet light at 2000 mJ / cm² and then heating at 190°C for 1 hour is 350°C or higher.

5. A cured product of the curable resin composition according to claim 1, 2, 3, or 4.

6. An adhesive comprising the curable resin composition according to claim 1, 2, 3, or 4.

7. An adhesive film made using the adhesive described in claim 6.

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