Cationically curable composition

Abstract

[Problem] To provide a cationically curable composition in which light-irradiation portions cure and even non-light-irradiation portions cure in molds of complicated shapes and which is usable in optical-member applications and adhesive applications. [Solution] Provided is a cationically curable composition which comprises an epoxy compound (A) including a fluorene skeleton containing an optionally substituted naphthalenediyl group, a mono- or higher-functional epoxy compound (B), a photoacid generator (C), a thermoacid generator (D), and an acid amplifier (E). Even non-light-irradiated portions of the cationically curable composition cure in molds of complicated shapes.

Description

Cationic curable composition

[0001] The present invention relates to a cationically curable composition, particularly an epoxy resin composition, and further to a cured product formed from the composition and a method for producing the cured product.

[0002] Photocurable resin compositions have better moldability than inorganic materials such as inorganic glass, and are therefore widely used in a variety of applications, including optical applications, optical device applications, display device applications, mechanical component materials, electrical and electronic component materials, as well as molding materials, paints, adhesives, and the like. Examples of conventional photocurable resin compositions include compositions containing epoxy resins and inorganic oxide particles. Optical transmission paths are used not only to transmit light over long distances but also within optical circuits, where optical transmission paths are formed on substrates using microfabrication techniques. In such cases, resin compositions are required to have not only good optical properties but also good moldability so that they can function as cured products. Photocurable epoxy resin compositions that are cured with light are also widely used as adhesives. Adhesives sometimes require molds with complex shapes, and in such cases, good moldability is required.

[0003] Many photocurable epoxy resin compositions have been disclosed. For example, Patent Document 1 discloses a heat- and light-curable resin composition containing an aromatic epoxy compound, an alicyclic epoxy compound and / or a hydrogenated epoxy compound, and a cationic curing catalyst. Examples in the same document include examples of thermal curing, and evaluations of transmittance and refractive index are described. Patent Document 2 discloses a photosensitive epoxy resin composition for optical waveguides, which has high transparency and excellent heat resistance and contains a multifunctional epoxy resin, a bisphenol A-type solid epoxy resin, a fluorene skeleton-containing solid epoxy resin, a fluorene skeleton-containing liquid epoxy resin, and a cationic curing initiator. Examples in the same document describe a process of UV exposure and post-heating, and evaluate the coatability, patterning resolution, and other properties. Patent Document 3 discloses a photosensitive epoxy resin composition with excellent heat coloration resistance and patterning properties, which contains an epoxy resin component and a photocationic polymerization initiator, and the epoxy resin component contains an epoxy resin with a trifunctional or higher bisphenol A skeleton. In the examples, a process of exposing to UV radiation and post-baking is described, and it is stated that the composition has good heat resistance, patterning ability, and flexibility. In addition, Patent Document 4 discloses a curable composition containing a curable compound and a cationic polymerization initiator, which can form a cured product having good heat resistance and adhesion to a substrate and has good curability. In the examples, a process of exposing to UV radiation and post-baking is described, and it is stated that the composition has good heat resistance and adhesion to a substrate.

[0004] The above-mentioned prior art documents describe examples of curing epoxy resin compositions by heat or light irradiation. Furthermore, in applications requiring optical properties after curing, the prior art documents have sought to achieve good optical properties such as transparency and refractive index, as well as good patternability as a cured product. However, the above-mentioned prior art documents do not include an acid amplifier or the like in the composition, and there is no description of a composition that cures in areas not exposed to light.

[0005] JP 2009-84310 A JP 2014-215531 A JP 2020-20927 A JP 2019-26760 A

[0006] The conventional photocurable resin compositions described in the above-mentioned prior art are compositions containing an aromatic or alicyclic epoxy resin, such as a fluorene skeleton-containing epoxy compound, and a photocurable component, and are designed to cure only the light-irradiated areas, but not the non-light-irradiated areas (hereinafter also referred to as dark areas). However, in recent years, when used in optical component applications or as adhesives, there has been a demand for curing not only the light-irradiated areas but also the non-light-irradiated areas at the same level as the light-irradiated areas. Therefore, the objective of the present invention is to provide a cationic curable composition that has excellent dark area curing properties, in which curing proceeds in the same way as the light-irradiated areas, even in complex-shaped molds, and has a high refractive index, making it suitable for use in adhesives and optical component applications.

[0007] In order to solve the above problems, the inventors added an acid multiplier to the composition in addition to the photoacid generator to generate more acid, and further added a thermal acid generator that can generate acid in response to light and heat.The combination of the thermal acid generator and the acid multiplier allows the acid generation region to expand more widely and simultaneously, and they discovered that sufficient curing can be achieved even in dark areas that are considerably far from the light-irradiated area, thereby completing the present invention.

[0008] That is, as a first aspect of the present invention, there is provided a cationically curable composition comprising: a fluorene skeleton-containing epoxy compound (A) represented by the following formula [1]; a monofunctional or di- or higher functional epoxy compound (B) different from the fluorene skeleton-containing epoxy compound (A); a photoacid generator (C); a thermal acid generator (D); and an acid amplifier (E). (In formula [1], L １ and L ２each independently represent a naphthalenediyl group which may have a substituent, and m and n each independently represent an integer of 0 to 10.) A second aspect relates to the cationically curable composition according to the first aspect, in which the epoxy compound (B) is a monofunctional or di- or higher functional aromatic epoxy compound. A third aspect relates to the cationically curable composition according to the second aspect, in which the epoxy compound (B) is a difunctional aromatic epoxy compound. A fourth aspect relates to the cationically curable composition according to the first aspect, in which the thermal acid generator (D) is an onium salt represented by the following formula [2]: [In formula [2], R １ , R ２ , R ３ and R ４ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted heterocyclic oxy group; R １ , R ２ , R ３ and R ４ may be bonded to each other to form a ring structure, and X － is SbF ６ － , P.F. ６ － , B(C ６ F ５ ) ４ － , Ga(C ６ F ５ ) ４ － , Ga(C ６ F ５ ) ２ F ２ － , Ga(C ６ F ５ ) F ３ － , C.F. ３ SO ３ － or C(CF ３ SO ２ ) ３ －

[0023] As a fifth aspect, the present invention relates to the cationically curable composition according to the first aspect, in which the acid amplifier (E) is a sulfonate ester compound. As a sixth aspect, the present invention relates to the cationically curable composition according to the fifth aspect, in which the sulfonate ester compound is an aromatic sulfonate ester compound having a structure represented by formula [3]. (In formula [3], Ar １ represents a benzene ring, a naphthalene ring, or an anthracene ring which may be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a hydroxy group, a nitro group, a cyano group, an amino group, a halogen group, a carboxyl group, and an alkoxycarbonyl group having 1 to 6 carbon atoms; R ５ and R ６ each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, or R ５ and R 6 may be bonded to each other to form a ring having 3 to 8 carbon atoms.) As a seventh aspect, the present invention relates to the cationically curable composition according to the sixth aspect, in which the aromatic sulfonate ester compound is a toluenesulfonate ester compound. As an eighth aspect, the present invention relates to the cationically curable composition according to the first aspect, in which the photoacid generator (C) is an onium salt having a cation moiety represented by the following formula [4]: (In formula [4], R ７ , R ８ and R ９ are each independently a hydrogen atom, a phenylsulfanyl group, an aryl group having 6 to 10 carbon atoms, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.) A ninth aspect relates to the cationically curable composition according to the second aspect, further comprising a monofunctional or difunctional alicyclic epoxy compound (F). A tenth aspect relates to the cationically curable composition according to the ninth aspect, in which the alicyclic epoxy compound (F) is a difunctional alicyclic epoxy compound. An eleventh aspect relates to the cationically curable composition according to the ninth aspect, in which the alicyclic epoxy compound (F) is a compound represented by the following formula [5]: (In formula [5], R １０ and R １１each independently represents a hydrogen atom, or an organic group containing a linear or branched alkyl group having 1 to 6 carbon atoms, which may have an ester group or an ether group, a cyclic alkyl group having 3 to 6 carbon atoms, a linear or branched alkylene group having 1 to 6 carbon atoms, or a combination thereof, wherein the linear alkyl group having 2 or more carbon atoms, the branched alkyl group having 3 or more carbon atoms, or the cyclic alkyl group may form an epoxy ring together with adjacent carbon atoms, or R １０ and R １１ may be bonded to each other to form a ring having 4 to 6 carbon atoms, and in this case, may be bonded to adjacent carbon atoms constituting the ring to form an epoxy ring.) As a twelfth aspect, the present invention relates to the cationically curable composition according to the first aspect, in which the fluorene skeleton-containing epoxy compound (A) is a compound represented by formula [6]. According to a thirteenth aspect, the present invention relates to the cationically curable composition according to the ninth aspect, in which the alicyclic epoxy compound (F) is at least one compound represented by the following formula [7], [8], or [9]: The fourteenth aspect relates to the cationic curable composition according to any one of the first to thirteenth aspects, which is used for an adhesive. The fifteenth aspect relates to the cationic curable composition according to any one of the first to thirteenth aspects, which is used for an optical component used in an optical transmission path. The sixteenth aspect relates to a cured product, which is a polymer of the cationic curable composition according to any one of the first to thirteenth aspects. The seventeenth aspect relates to a method for producing a cured product, including a photocuring step of irradiating the cationic curable composition according to any one of the first to thirteenth aspects with light from the initial step through all steps, a low-temperature heating step of heating the composition in a temperature range in which the thermal acid generator (D) does not undergo an acid-generating reaction, and a high-temperature heating step of subsequently heating the composition in a temperature range higher than the temperature range of the low-temperature heating step. The eighteenth aspect relates to a method for producing a cured product according to the seventeenth aspect, in which the low-temperature heating step is carried out in a temperature range of 40 to 125°C, and the high-temperature heating step is carried out in a temperature range of 130°C or higher.

[0009] The cationic curable composition of the present invention has excellent dark curing properties, meaning that curing proceeds even in dark areas. Due to this property, when the cationic curable composition of the present invention is filled into a structure with a complex shape, i.e., a structure having both light-irradiated and non-irradiated areas, curing proceeds not only in the light-irradiated areas but also in the non-irradiated areas. In particular, the inclusion of a thermal acid generator and an acid amplifier allows acid to be continuously generated, thereby enabling more effective curing even in dark areas. Furthermore, the cured product, which is a polymer of the cationic curable composition of the present invention, can have a high refractive index. Therefore, the cationic curable composition of the present invention can be used as a material for optical components used in optical transmission paths and as an adhesive.

[0010] FIG. 1 is a schematic diagram showing the state of the evaluation device when light is irradiated in the evaluation of dark curability in the examples.

[0011] [Cationically Curable Composition] The cationic curable composition of the present invention contains a fluorene skeleton-containing epoxy compound (A), a monofunctional or difunctional or higher functional epoxy compound (B) different from the fluorene skeleton-containing epoxy compound (A), a photoacid generator (C), a thermal acid generator (D), and an acid amplifier (E). In addition to the cationic curable composition, a monofunctional or difunctional alicyclic epoxy compound (F) may also be contained. In this specification, the above epoxy compounds (A), (B), and (F) as well as other epoxy compounds described below are collectively referred to as the "resin component," and "monofunctional or bifunctional" means that the composition contains one or two epoxy groups as functional groups.

[0012] [Fluorene Skeleton-Containing Epoxy Compound (A)] The fluorene skeleton-containing epoxy compound (A) used in the present invention is a compound represented by the following formula [1]. (In formula [1], L １ and L ２ each independently represents a naphthalenediyl group which may have a substituent, and m and n each independently represent an integer of 0 to 10.

[0013] L １ and L ２Examples of the substituent on the naphthalenediyl group (on the naphthalene ring) in L include alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, and t-butyl. １ and L ２ The number of substituents in the naphthalenediyl group in L is independently 0 to 6, preferably 0 to 2, more preferably 0 or 1, and most preferably 0. １ and L ２ The types of the substituents in may be the same or different. When the same naphthalene ring has two or more substituents, they may be the same or different.

[0014] The fluorene skeleton-containing epoxy compound (A) is preferably a compound represented by the following formula [6]:

[0015] The fluorene skeleton-containing epoxy compound (A) can be a commercially available product. Examples include OGSOL (registered trademark) CG-500 and EG-280 (manufactured by Osaka Gas Chemicals Co., Ltd.). Such fluorene skeleton-containing epoxy compounds having a naphthalene ring can be used alone or in combination of two or more. Furthermore, from the viewpoint of the solubility and refractive index of the resin component, for example, OGSOL (registered trademark) CG-500 can be used alone.

[0016] The fluorene skeleton-containing epoxy compound (A) can be contained in an amount of, for example, 5 to 60 parts by mass, preferably 10 to 50 parts by mass, further 15 to 45 parts by mass, and even more preferably 20 to 40 parts by mass, relative to the total amount of epoxy compounds (100 parts by mass in total). If the amount of fluorene skeleton-containing epoxy compound (A) is too small, it is difficult to obtain a sufficient refractive index. Conversely, if it is too large, precipitation occurs, resulting in deterioration of storage stability and deterioration of film-formability.

[0017] [Monofunctional, Difunctional, or More Functional Epoxy Compound (B)] The present invention may include a monofunctional, difunctional, or more functional epoxy compound (B) different from the epoxy compound (A). The monofunctional, difunctional, or more functional epoxy compound (B) may include a monofunctional, difunctional, or more functional aromatic epoxy compound and a monofunctional, difunctional, or more functional alicyclic epoxy compound. The monofunctional, difunctional, or more functional epoxy compound (B) is preferably included in an amount of, for example, 10 to 90 parts by mass, more preferably 40 to 85 parts by mass, more preferably 45 to 80 parts by mass, and even more preferably 50 to 80 parts by mass, relative to the total amount (100 parts by mass) of the epoxy compounds. If the amount of aromatic epoxy compound (B) is less than 10 parts by mass, it may be difficult to obtain a sufficient refractive index or a uniform film. Conversely, if it is more than 90 parts by mass, it may lead to a decrease in curability.

[0018] [Monofunctional or Difunctional or More Functional Aromatic Epoxy Compound] The monofunctional or difunctional or more functional aromatic epoxy compound is not particularly limited as long as it is a compound having one or more epoxy groups. Examples of monofunctional aromatic epoxy compounds include glycidyl phenyl ether, 2-phenylphenol glycidyl ether, and phenol (EO) ５ Examples of the aromatic epoxy compound having two or more functional groups include glycidyl ether and p-tert-butylphenyl glycidyl ether. As the aromatic epoxy compound having two or more functional groups, for example, those having a basic skeleton of bisphenol can be used, and among them, epoxy compounds having a bisphenol A skeleton or a bisphenol F skeleton are preferred. However, in terms of exposure sensitivity and curability, compounds having two epoxy groups can be used in a preferred embodiment.

[0019] Commercially available monofunctional or difunctional or higher aromatic epoxy compounds can be used. Examples of the monofunctional aromatic epoxy compound (B) include phenyl glycidyl ether (e.g., Denacol (registered trademark) EX-141, manufactured by Nagase ChemteX Corporation), phenol (EO) 5 glycidyl ether (e.g., Denacol (registered trademark) EX-145, manufactured by Nagase ChemteX Corporation), and p-tert-butylphenyl glycidyl ether (e.g., Denacol (registered trademark) EX-146, manufactured by Nagase ChemteX Corporation). Examples of the difunctional or higher aromatic epoxy compound (B) include jER (registered trademark) 806, a bisphenol F type epoxy compound manufactured by Mitsubishi Chemical Corporation, and jER (registered trademark) 828, a bisphenol A type epoxy compound manufactured by Mitsubishi Chemical Corporation.

[0020] [Monofunctional or Difunctional or More Functional Alicyclic Epoxy Compound (Monofunctional or Bifunctional Alicyclic Epoxy Compound (F))] The monofunctional or difunctional or more functional epoxy compound (B) used in the present invention may contain a monofunctional or difunctional or more functional alicyclic epoxy compound, or may contain a monofunctional or bifunctional alicyclic epoxy compound (F). Hereinafter, the monofunctional or bifunctional alicyclic epoxy compound will also be described as a monofunctional or bifunctional alicyclic epoxy compound (F). The monofunctional or difunctional or more functional alicyclic epoxy compound is not particularly limited as long as it is a compound having one or two or more alicyclic epoxy groups. In a preferred embodiment, the alicyclic epoxy compound (F) is a liquid embodiment, and in terms of exposure sensitivity and curability, a compound having two epoxy groups introduced into an alicyclic skeleton can be used.

[0021] Examples of the monofunctional alicyclic epoxy compound [monofunctional alicyclic epoxy compound (F)] include compounds represented by the following formula [5]: (In formula [5], R １０ and R １１each independently represents a hydrogen atom or an organic group containing a linear or branched alkyl group having 1 to 6 carbon atoms, which may have an ester group or an ether group, a cyclic alkyl group having 3 to 6 carbon atoms, a linear or branched alkylene group having 1 to 6 carbon atoms, or a combination thereof, wherein the linear alkyl group having 2 or more carbon atoms, the branched alkyl group having 3 or more carbon atoms, or the cyclic alkyl group may form an epoxy ring together with adjacent carbon atoms, or R １０ and R １１ may be bonded to each other to form a ring having 4 to 6 carbon atoms, and in this case, adjacent carbon atoms constituting the ring may be joined to form an epoxy ring.) The above "represents an organic group containing a linear or branched alkyl group having 1 to 6 carbon atoms, a cyclic alkyl group having 3 to 6 carbon atoms, a linear or branched alkylene group having 1 to 6 carbon atoms, or a combination thereof, which may have an ester group or an ether group" may mean, for example, an alkylene group having 1 carbon atom to which an ester group is bonded and which is further bonded to a cyclic alkyl group having 6 carbon atoms, and an alkyl group is bonded to one carbon atom of the cyclic alkyl group. Of course, combinations such as an ether group being bonded instead of the ester group, or a C-C bond of the cyclic alkyl group being shared by another cyclic alkyl group are also possible.

[0022] Examples of the linear or branched alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutyl group, a 1,1-dimethylpropyl group, a 1,2-dimethylpropyl group, a 2,2-dimethylpropyl group, a 1-ethylpropyl group, an n-hexyl group, a 1-methylpentyl group, a 2-methylpentyl group, a 3-methylpentyl group, a 4-methylpentyl group, a 1,1-dimethylbutyl group, a 1,2-dimethylbutyl group, a 1,3-dimethylbutyl group, a 2,2-dimethylbutyl group, a 2,3-dimethylbutyl group, a 3,3-dimethylbutyl group, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1,1,2-trimethylpropyl group, a 1,2,2-trimethylpropyl group, a 1-ethyl-1-methylpropyl group, and a 1-ethyl-2-methylpropyl group. Examples of the straight-chain or branched-chain alkylene group having 1 to 6 carbon atoms include divalent groups obtained by removing one hydrogen atom from any carbon atom in the group of straight-chain or branched-chain alkyl groups having 1 to 6 carbon atoms. Examples of the cyclic alkyl group having 3 to 6 carbon atoms include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group. １０ and R １１ may be bonded to each other to form a ring having 4 to 6 carbon atoms," the newly formed ring having 4 to 6 carbon atoms may be in a bonded state in which the C-C bond of the two cyclohexane rings is shared, as in decahydronaphthalene, or may form a spiro ring having a spiro atom, as in spiro[5.5]undecane.

[0023] In a preferred embodiment, the difunctional or higher functional alicyclic epoxy compound [difunctional alicyclic epoxy compound (F)] is a compound represented by the following formula [7], [8], or [9]. These compounds have a low molecular weight and are liquid compounds, and are suitable from the viewpoint of adjusting the viscosity of the composition.

[0024] The alicyclic epoxy compound [alicyclic epoxy compound (F)] can be a commercially available product. Examples of the bifunctional alicyclic epoxy compound (F) include diepoxybicyclohexyl (e.g., Celloxide (registered trademark) 8000 and 8010, manufactured by Daicel Corporation), 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexenecarboxylate (e.g., CEL-2021P: Celloxide (registered trademark) 2021P, manufactured by Daicel Corporation), epsilon-caprolactone-modified 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate (e.g., Celloxide (registered trademark) 2081, manufactured by Daicel Corporation), bis(3,4-epoxycyclohexylmethyl)adipate, and diepoxidized tetrahydroindene (e.g., Epocalic (registered trademark) THI-DE, manufactured by ENEOS Corporation). Furthermore, for example, as the monofunctional alicyclic epoxy compound, 3,4-epoxycyclohexylmethyl methacrylate (e.g., Cyclomer (registered trademark) M-100, manufactured by Daicel Corporation), 3,4-epoxycyclohexylmethyl methacrylate, 1,2-epoxy-4-vinylcyclohexane (e.g., Celloxide (registered trademark) 2000, manufactured by Daicel Corporation), 1,2,8,9-diepoxylimonene (e.g., Celloxide (registered trademark) 3000, manufactured by Daicel Corporation), and the like can be used.

[0025] The alicyclic epoxy compound (F) can be contained in an amount of, for example, 0 to 70 parts by mass, preferably 0 to 65 parts by mass, further 0 to 60 parts by mass, and even more preferably 5 to 50 parts by mass, relative to the total amount of epoxy compounds (100 parts by mass in total). If the amount of alicyclic epoxy compound (F) is too small, the viscosity increases, making handling difficult, whereas if it is too large, it becomes difficult to obtain a sufficient refractive index.

[0026] [Photoacid Generator (C)] The cationic curable composition of the present invention contains a photoacid generator (C). Specific examples of the photoacid generator (C) include onium salts such as iodonium salts, sulfonium salts, phosphonium salts, and selenium salts, metallocene complex compounds, iron arene complex compounds, disulfone-based compounds, sulfonic acid derivative compounds, triazine-based compounds, acetophenone derivative compounds, and diazomethane-based compounds.

[0027] Among the onium salts, examples of iodonium salts include diaryliodonium salts such as chloride, bromide, mesylate, tosylate, trifluoromethanesulfonate, tetrafluoroborate, tetrakis(pentafluorophenyl)borate, hexafluorophosphate, hexafluoroarsenate, and hexafluoroantimonate of diaryliodonium such as diphenyliodonium, 4,4'-dichlorodiphenyliodonium, 4,4'-dimethoxydiphenyliodonium, 4,4'-di-tert-butyldiphenyliodonium, 4-methylphenyl(4-(2-methylpropyl)phenyl)iodonium, 3,3'-dinitrophenyliodonium, 4-(1-ethoxycarbonylethoxy)phenyl(2,4,6-trimethylphenyl)iodonium, and 4-methoxyphenyl(phenyl)iodonium. As the sulfonium salt, a photoacid generator that is a sulfonium salt having a cation moiety represented by the following formula [4] is preferred from the viewpoint of high thermal stability and acid generation efficiency upon irradiation with ultraviolet light. (In formula [4], R ７ , R ８ and R ９ are each independently a hydrogen atom, a phenylsulfanyl group, an aryl group having 6 to 10 carbon atoms, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0028] Examples of sulfonium salts having a cation moiety represented by the above formula [4] include triarylsulfonium salts such as chlorides, bromides, trifluoromethanesulfonates, tetrafluoroborate, hexafluorophosphate, hexafluoroarsenate, and hexafluoroantimonate of triarylsulfonium such as triphenylsulfonium, diphenyl(4-tert-butylphenyl)sulfonium, tris(4-tert-butylphenyl)sulfonium, diphenyl(4-methoxyphenyl)sulfonium, tris(4-methylphenyl)sulfonium, tris(4-methoxyphenyl)sulfonium, tris(4-ethoxyphenyl)sulfonium, diphenyl(4-(phenylthio)phenyl)sulfonium, and tris(4-(phenylthio)phenyl)sulfonium.

[0029] Examples of the phosphonium salt include arylphosphonium salts such as chlorides, bromides, tetrafluoroborates, hexafluorophosphates, and hexafluoroantimonates of triarylphosphoniums or tetraarylphosphoniums such as tetraphenylphosphonium, ethyltriphenylphosphonium, tetra(p-methoxyphenyl)phosphonium, ethyltri(p-methoxyphenyl)phosphonium, and benzyltriphenylphosphonium.

[0030] Examples of the selenium salt include triarylselenium salts such as triphenylselenium hexafluorophosphate. Examples of the iron arene complex compounds include bis(η5-cyclopentadienyl)(η6-isopropylbenzene)iron(II) hexafluorophosphate.

[0031] Among these, onium salts such as iodonium salts and sulfonium salts can be preferably used as the photoacid generator. Commercially available products can be used, and examples of such products include triarylsulfonium salts such as CPI-310FG, CPI-310B, CPI-200K, and CPI-101A.

[0032] These photoacid generators (C) can be used alone or in combination of two or more. The photoacid generator (C) can typically be included in an amount of, for example, 0.05 to 10 parts by mass, preferably 0.1 to 5 parts by mass, further 0.15 to 3 parts by mass, and even more preferably 0.2 to 2 parts by mass, relative to 100 parts by mass of the total mass of the epoxy compound (resin component). If the amount of photoacid generator (C) is less than 0.05 parts by mass, there is a risk that the curing reaction will not proceed sufficiently. On the other hand, if it exceeds 10 parts by mass, there is a risk that the degree of polymerization of the polymer will decrease, making the polymer brittle and prone to cracking.

[0033] [Thermal Acid Generator (D)] The cationic curable composition of the present invention contains a thermal acid generator (D). The thermal acid generator (D) used in the present invention preferably has an activation temperature of 80 to 220°C, more preferably 90 to 220°C, and even more preferably 100 to 200°C. Examples of the thermal acid generator (D) include perfluoroalkylsulfonates (trifluoromethanesulfonates, perfluorobutanesulfonates, etc.), hexafluorophosphates, boron trifluoride salts, boron trifluoride ether complex compounds, onium salts represented by the following formula [2], and onium salts represented by the following formula [2b]. Of these, the thermal acid generator (D) is preferably an onium salt represented by the following formula [2] in which the cation moiety is a quaternary ammonium. [In formula [2], R １ , R ２ , R ３ and R ４ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted heterocyclic oxy group; R １ , R ２ , R ３ and R ４ may be bonded to each other to form a ring structure, and X － is SbF ６ － , P.F. ６ － , B(C６ F ５ ) ４ － , Ga(C ６ F ５ ) ４ － , Ga(C ６ F ５ ) ２ F ２ － , Ga(C ６ F ５ ) F ３ － , C.F. ３ SO ３ － or C(CF ３ SO ２ ) ３ － [In formula [2b], R ２１ , R ２２ and R ２３ In formula [2], R １ , R ２ and R ３ Also, R ２１ , R ２２ and R ２３ may be bonded to each other to form a ring structure. － is X in formula [2] － is the same as

[0034] Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, and an aralkyl group. Examples of the aralkyl group include a benzyl group, a naphthylmethyl group, and a cinnamyl group. These alkyl groups may have a substituent. Examples of the aryl group include a phenyl group, a naphthyl group, and a biphenyl group. These aryl groups may have a substituent.

[0035] Examples of the alkenyl group include a propenyl group, a 2-butenyl group, a 2-pentanyl group, and a 2-hexanyl group. Examples of the heterocyclic group include a pyridinyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Examples of the aryloxy group include a 4-phenylmethoxy group, a 4-phenylethoxy group, and a 4-phenyloxycarbonylmethyl group. Examples of the heterocyclic oxy group include a 4-cyclohexaneoxide group. These groups may have a substituent.

[0036] Examples of the substituent in each of the above alkyl groups, aryl groups, etc. include alkyl groups such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group, hexyl group, etc.; aryl groups such as phenyl group, naphthyl group, etc.; alkoxy groups such as methoxy group, ethoxy group, propoxy group, butoxy group, etc.; alkoxycarbonyl groups such as acetoxy group, propionyloxy group, decylcarbonyloxy group, dodecylcarbonyloxy group, etc.; ester groups such as methoxycarbonyl group, ethoxycarbonyl group, benzoyloxy group, etc.; phenylthio group; halogen atoms such as fluorine atom, chlorine atom, bromine atom, iodine atom, etc.; cyano group; nitro group; hydroxy group, etc. The substitution position of these substituents is not particularly limited and may be any position.

[0037] X in formula (2) － represents a counter anion of the nitrogen onium cation. － Examples of the material include SbF ６ － , P.F. ６ － , B(C ６ F ５ ) ４ － , Ga(C ６ F ５ ) ４ － , Ga(C ６ F ５ ) ２ F ２ － , Ga(C ６ F５ ) F ３ － , C.F. ３ SO ３ － and C(CF ３ SO ２ ) ３ － When the nucleophilicity of the anion is low, better curability can be obtained, so SbF ６ － , B(C ６ F ５ ) ４ － , C.F. ３ SO ３ － , C(CF ３ SO ２ ) ３ － is preferred.

[0038] R １ , R ２ , R ３ and R ４ may be bonded to each other to form a ring structure, for example, R １、 R ２ , R ３ and R ４ Adjacent groups among these bond to each other to form a ring structure. Examples of nitrogen onium cations having a ring structure include cations represented by the following general formula (11). Examples of the ring structure Q include heterocycles, aromatic rings, heteroaromatic rings (pyridinium rings, etc.), and alicyclic rings. The ring structure Q is, for example, a multi-membered ring such as a four-membered ring, a five-membered ring, a six-membered ring, or a seven-membered ring. The ring structure Q may be unsubstituted or may have a substituent. Examples of the substituent include the substituents described above for each group such as an alkyl group and an aryl group. m represents 1 or 2. R ２４ is R １ , R ２ , R ３ and R ４ is a group equivalent to

[0039] These thermal acid generators (D) can be used alone or in combination of two or more. The thermal acid generator (D) can typically be included in an amount of, for example, 0.01 to 5 parts by mass, preferably 0.02 to 3 parts by mass, further 0.03 to 1 part by mass, and even more preferably 0.05 to 1 part by mass, per 100 parts by mass of the total mass of the epoxy compound (resin component). If the amount of the thermal acid generator (D) is less than 0.01 part by mass, acid generation may not proceed sufficiently. Furthermore, if the amount exceeds 5 parts by mass, the degree of polymerization of the polymer may decrease, making the polymer brittle and prone to cracking.

[0040] [Acid Amplifier (E)] The cationic curable composition of the present invention contains an acid amplifying agent (E). The acid amplifying agent (E) of the present invention has the property of decomposing under the action of acid and continuously generating acid, so curing proceeds even in non-irradiated areas (dark areas). The cationic curable composition of the present invention is cured by the acid generated by the photoacid generator in the light-irradiated areas and the acid generated by the acid amplifying agent. In the non-irradiated areas (dark areas), the acid generated by the thermal acid generator and the acid generated in the light-irradiated areas further act to continuously generate acid, thereby progressing curing. Examples of such acid amplifying agents include sulfonate ester compounds (compounds containing sulfonate ester derivatives) and aromatic sulfonate ester compounds (compounds containing aromatic sulfonate ester derivatives).

[0041] There are no particular limitations on the sulfonate ester compound used. For example, an alkylsulfonate ester compound having an alkyl group having 1 to 10 carbon atoms may be used. The alkyl group having 1 to 10 carbon atoms may be substituted with a group selected from a phenyl group, a naphthyl group, an alkoxy group, and the like. Other examples include aromatic sulfonate ester compounds having an aromatic hydrocarbon ring such as a benzene ring, a naphthalene ring, an anthracene ring, a fluorene ring, and a naphthacene ring. The ester moiety of the sulfonate ester compound may be either an alkyl ester or an aryl ester.

[0042] The alkyl group having 1 to 10 carbon atoms includes those having a straight chain or a branched chain, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, an n-pentyl group, a 1-methyl-n-butyl group, a 2-methyl-n-butyl group, a 3-methyl-n-butyl group, a 1,1-dimethyl-n-propyl group, a 1,2-dimethyl-n-propyl group, a 2,2-dimethyl-n-propyl group, a 1-ethyl-n-propyl group, an n-hexyl group, a 1-methyl-n-pentyl group, a 2-methyl-n-pentyl ... Examples of the alkyl group include a methyl group, a 3-methyl-n-pentyl group, a 4-methyl-n-pentyl group, a 1,1-dimethyl-n-butyl group, a 1,2-dimethyl-n-butyl group, a 1,3-dimethyl-n-butyl group, a 2,2-dimethyl-n-butyl group, a 2,3-dimethyl-n-butyl group, a 3,3-dimethyl-n-butyl group, a 1-ethyl-n-butyl group, a 2-ethyl-n-butyl group, a 1,1,2-trimethyl-n-propyl group, a 1,2,2-trimethyl-n-propyl group, a 1-ethyl-1-methyl-n-propyl group, and a 1-ethyl-2-methyl-n-propyl group.

[0043] Specific examples of the alkylsulfonate compound include 1,4-bis(mesyloxy)cyclohexane, 1,4-bis(2,2,2-trifluoroethanesulfonyloxy)cyclohexane, 1,4-bis(trifluoromethanesulfonyloxy)cyclohexane, 1,3-bis(mesyloxy)cyclohexane, 1,3-bis(2,2,2-trifluoroethanesulfonyloxy)cyclohexane, 1,3-bis(trifluoromethanesulfonyloxy)cyclohexane, and 1,3-bis(2,2,2-trifluoroethanesulfonyloxy)propane.

[0044] From the viewpoint of storage stability and the like, it is preferable that the sulfonate ester compound used in the cationic curable composition of the present invention is not a compound that is easily decomposed by heat. Therefore, from the viewpoint of the thermal decomposition temperature, an aromatic sulfonate ester compound represented by formula [3] is preferably used, and Ar １ More preferred are aromatic sulfonate compounds containing toluenesulfonate esters in which is a toluene group. (In formula [3], Ar １ represents a benzene ring, a naphthalene ring, or an anthracene ring which may be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a hydroxy group, a nitro group, a cyano group, an amino group, a halogen group, a carboxyl group, and an alkoxycarbonyl group having 1 to 6 carbon atoms; R ５ and R ６ each represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, or R ５ and R 6 may be bonded to each other to form a ring having 3 to 8 carbon atoms.

[0045] Specific examples of aromatic sulfonate compounds containing toluenesulfonate include 1,3 bis(p-toluenesulfonyloxy)propane, 1,2 bis(p-toluenesulfonyloxy)ethane, 1,4-di-o-tosyl-2,3-o-isopropylidentreitol, triethylene glycol ditosylate, 2,3-dihydroxybutane-1,4-diylbis(p-toluenesulfonate), tetra(p-toluenesulfonyloxymethyl)methane, 1,2-propanediol di-p-tosylate, 1,2,4-tritosylbutanetriol, 2,3-butanediol di-p-tosylate, diethylene glycol di-p-tosylate, N,N-bis(2-(tosyloxy)ethyl)toluene-4-sulfonamide, 1,3-adamantanedimethanol di-p-tosylate, 1-benzyloxy-3-(p-tosyloxy) )-2-propanol, 4,4'-bis(p-toluenesulfonyloxy)isopropylidenecyclohexane, 1,3-bis(p-toluenesulfonyloxy)cyclohexane, 1,4-bis(p-toluenesulfonyloxy)cyclohexane, (R)-(-)-1-benzyloxy-3-(p-tosyloxy)-2-propanol, p-toluenesulfonic acid cyclohexyl ester, pinanediol mono(p-toluenesulfonate), p-toluenesulfonic acid cyclopentyl ester, 1-(p-toluenesulfonyloxy)-4-trifluoromethanesulfonyloxycyclohexane, 1-(p-toluenesulfonyloxy)-4-(3,3,3-trifluoroethanesulfonyloxy)cyclohexane, and other aromatic sulfonate ester compounds. Furthermore, the acid amplifiers can be used alone or in combination of two or more.

[0046] These acid amplifiers (E) can be used alone or in combination of two or more. The acid amplifier (E) can typically be included in an amount of, for example, 0.1 to 20 parts by mass, preferably 0.3 to 15 parts by mass, further 0.5 to 10 parts by mass, and even more preferably 1.0 to 5 parts by mass, per 100 parts by mass of the total mass of the epoxy compound (resin component). If the amount of the acid amplifier (E) is less than 0.1 parts by mass, the curing reaction may not proceed sufficiently in dark areas. Furthermore, if the amount of the acid amplifier (E) exceeds 20 parts by mass, the degree of polymerization of the polymer decreases, potentially making the polymer brittle and prone to cracking.

[0047] In addition, the acid generated from the photoacid generator (C), the thermal acid generator (D) and the acid amplifier (E) is preferably an acid generally called a strong acid. For example, the acid generated from the photoacid generator (C) is ６ F ５ ) ４ GaH, {(CF ３ ) ２ C ６ H ３} ４ GaH, (CF ３ C ６ H ４ ) ４ GaH, (C ６ F ５ ) ４ BH, {(CF ３ ) ２ C ６ H ３} ４ BH, (CF ３ C ６ H ４ ) ４ BH, (C ６ F ５ ) ２ BF ２ H, (CF ３ CF ２ ) ２ PF ４ H, (CF ３ CF ２ ) ３ PF ３ H, {(CF ３ ) ２ CF} ２ PF４ H, {(CF ３ ) ２ CF} ３ PF ３ The acid generated from the acid multiplier (E) is preferably CF ３ CF ２ CF ２ CF ２ SO ３ H, C.F. ３ CF ２ CF ２ SO ３ H, C.F. ３ CF ２ SO ３ H, CH ３ (C ６ H ６ ) SO ３ H, C.F. ３ SO ３ H, H ２ SO ４ However, the type of acid is not limited to these.

[0048] [Other Epoxy Compounds] The cationic curable composition of the present invention may contain other epoxy compounds in addition to the epoxy compounds (A), (B), and (F) described above, as long as the effects of the present invention are not impaired. Examples of such epoxy compounds include heterocycle-containing epoxy compounds such as triglycidyl isocyanurate and aliphatic epoxy compounds. Specific examples of the aliphatic epoxy compounds include monofunctional epoxy compounds such as glycidyl ethers of aliphatic alcohols and glycidyl esters of alkylcarboxylic acids, and polyglycidyl ethers of aliphatic polyhydric alcohols or their alkylene oxide adducts. Representative specific compounds of these include allyl glycidyl ether; glycidyl ethers of monoalcohols such as butyl glycidyl ether, 2-ethylhexyl glycidyl ether, and C12-13 mixed alcohol glycidyl ether; glycidyl ethers of polyhydric alcohols such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol tetraglycidyl ether, dipentaerythritol hexaglycidyl ether, polyethylene glycol diglycidyl ether, and polypropylene glycol diglycidyl ether; and polyglycidyl ethers of polyether polyols, which are adducts of one or more alkylene oxides with aliphatic polyhydric alcohols such as propylene glycol, trimethylolpropane, and glycerin. These other epoxy compounds may be contained in an amount of, for example, 30 parts by mass or less, 20 parts by mass or less, 10 parts by mass or less, or 5 parts by mass or less relative to the total amount (100 parts by mass) of the epoxy compounds.

[0049] [Organic Solvent] The cationic curable composition of the present invention may contain an organic solvent. When the prepared composition has a low viscosity, there is no need to add an organic solvent, enabling good film formation. In this case, since the composition is solvent-free, there is also the advantage that a process of volatilizing the organic solvent by heat treatment or the like after film formation is not required. Furthermore, the absence of an organic solvent significantly reduces concerns about health hazards caused by inhalation by the organic solvent during its evaporation and corrosion of surrounding equipment. Since the cationic curable composition of the present invention has a relatively low viscosity, the incorporation of an organic solvent is not essential. However, even if an organic solvent is contained, it can be added in any proportion without losing the above-described effects of the present invention. There are no particular restrictions on the organic solvent that can be used in the present invention as long as it is an organic solvent commonly used in the technical field. However, it is desirable to avoid the use of extremely high-polarity or low-polarity solvents, such as water or hydrocarbon solvents such as hexane, as they may cause precipitation or phase separation. Furthermore, caution is required when adding a large amount of organic solvent, as this may prevent a sufficient film thickness from being achieved during film formation.

[0050] [Other Additives] The cationic curable composition of the present invention may contain other additives commonly used in the art, as long as the effects of the present invention are not impaired. Examples of other additives include thermal acid generators, antireflection agents, ultraviolet absorbers, antioxidants, light stabilizers, sensitizers, surfactants, crosslinking agents, leveling agents, and silane coupling agents. When these other additives are used, they are typically blended in an amount of 10 parts by mass or less, 5 parts by mass or less, or 3 parts by mass or less, per 100 parts by mass of the total mass of the epoxy compound (resin component).

[0051] [Preparation of Cationic Curable Composition] As described below, the cationic curable composition of the present invention can be suitably used as an adhesive or a material for forming an optical transmission path. The method for preparing the cationic curable composition of this embodiment is not particularly limited. Examples of the preparation method include a method in which the above-mentioned components (A), (B), (C), (D), and (E), and optionally component (F), as well as other epoxy compounds and other additives, are further added and mixed to form a uniform solution, or a method in which a conventional organic solvent is further used in addition to these components. In the cationic curable composition of the present invention, the amounts of each component can be, for example, 10 to 50 parts by weight of the fluorene skeleton-containing epoxy compound (A), 40 to 90 parts by weight of the aromatic epoxy compound (B), and 1 to 10 parts by weight of the alicyclic epoxy compound (F), assuming the total weight of the epoxy compounds (resin components) to be 100 parts by weight. Also, the amounts of the photoacid generator (C), the thermal acid generator (D), the acid amplifier (E), and the other additives can be 0.1 to 5 parts by weight, 0.05 to 2 parts by weight, 0.1 to 10 parts by weight, and 0 to 10 parts by weight, respectively, relative to 100 parts by weight of the total weight of the epoxy compounds (resin components). When the organic solvent is used, the solids content of the cationic curable composition is not particularly limited as long as each component is uniformly dissolved in the organic solvent, but is, for example, 60% by weight or more, or 70% by weight or more. Preferably, the solids content of the composition can be, for example, 75% to 99% by weight. Here, the solid content refers to all components of the cationic curable composition excluding the organic solvent component. The cationic curable composition is preferably used after filtering using a filter having a pore size of 0.05 to 5 μm.

[0052] [Viscosity] The cationic curable composition of the present invention preferably has a viscosity that allows for excellent workability during preparation. For example, the viscosity of the cationic curable composition at 25°C can be 10 to 10,000 mPa·s, preferably 20 to 5,000 mPa·s, further 50 to 2,000 mPa·s, and even more preferably 100 to 1,000 mPa·s. If the viscosity is higher than 10,000 mPa·s, the acid may not diffuse and the dark areas may not be cured. If the viscosity is lower than 10 mPa·s, the composition may be too fluid and not remain on the adhesive surface, resulting in poor workability.

[0053] [Method of Manufacturing Cured Product] A method of manufacturing a cured product according to one embodiment of the present invention will be described below. For example, the cured product is preferably manufactured by the following manufacturing method. A silicon wafer substrate was cleaned using an ultraviolet ozone cleaning device. Silicon rubber approximately 0.5 mm thick was used as a spacer. The cationic curable composition was dropped onto the silicon wafer substrate, and approximately half of the dropped and spread composition, as viewed from above, was covered with release-treated glass covered with 50 μm thick Kapton (registered trademark) tape. The composition was then irradiated with 1 to 10 J / cm 2 of a xenon light source lamp (MAX-302, manufactured by Asahi Spectroscopy Co., Ltd.) through a 365 nm bandpass filter. ２ (20 mW / cm ２ ) and irradiated with light (photocuring step, Figure 1). After exposure, to promote diffusion of the acid, the film was heated at 40 to 80°C for 15 to 60 minutes, at 100 to 125°C for 15 to 60 minutes (low-temperature heating step), and then heated at 130°C or higher for 15 to 60 minutes (high-temperature heating step). After these steps, the film was visually inspected to see if it had cured overall, even in dark areas where the acid would not diffuse. In the low-temperature heating step, heating was performed in two temperature ranges, but heating in either one of the temperature ranges may be performed. Furthermore, heating may be performed while irradiating with light in the low-temperature heating step, and heating may be performed while irradiating with light in the high-temperature heating step.

[0054] [Adhesive] The adhesive of the present invention includes a cured product of the above-mentioned cationic curable composition, and preferably consists of a cured product of the cationic curable composition. The cured product of the cationic curable composition of the present invention is characterized by high heat resistance and a high refractive index, and can be suitably used as an adhesive for optical components, etc. In particular, the cationic curable composition of the present invention has dark-area curing properties, and is therefore useful as an adhesive for bonding components having shapes that generate dark areas when cured by light irradiation.

[0055] [Light Transmission Path] The light transmission path of the present invention includes a cured product of the above-described cationic curable composition, and preferably consists of the cured product of the cationic curable composition. For example, in one embodiment, the light transmission path of the present invention is a light transmission path consisting of a core and a clad layer that surrounds the entire outer periphery of the core and has a refractive index lower than that of the core. The core layer or the clad layer may consist of the cured product of the above-described cationic curable composition.

[0056] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The compounds and their abbreviations used in the examples are as follows:

[0057] [Fluorene Skeleton-Containing Epoxy Compound (A)] The following fluorene skeleton-containing diepoxy compound was used as the fluorene skeleton-containing epoxy compound: CG-500: OGSOL (registered trademark) CG-500, manufactured by Osaka Gas Chemicals Co., Ltd.

[0058] [Aromatic Epoxy Compound (B)] The following bifunctional aromatic epoxy compound was used as the aromatic epoxy compound (B): jER806: bisphenol F type epoxy resin, manufactured by Mitsubishi Chemical Corporation The following monofunctional aromatic epoxy compounds were used as the aromatic epoxy compound (B): EX-141: Denacol (registered trademark) EX-141 (phenyl glycidyl ether), manufactured by Nagase ChemteX Corporation

[0059] [Photoacid Generator (C)] The following photoacid generators were used: CPI-310FG: Triarylsulfonium salt-type photoacid generator, manufactured by San-Apro Co., Ltd. CPI-200K: Sulfonium salt-type photoacid generator (50% propylene carbonate solution), manufactured by San-Apro Co., Ltd.

[0060] [Thermal Acid Generator (D)] The following was used as the thermal acid generator: TAG-2689: quaternary ammonium salt thermal acid generator, manufactured by KING INDUSTRIES, activation temperature: 130 to 170°C In the above formula, R ２５ , R ２６ , R ２７ represents an alkyl group, and R ２５ , R ２６ , R ２７ At least one of the groups is an alkyl group having an aromatic ring as a substituent, and Ar represents an aryl group which may have a substituent.

[0061] [Acid Amplifier (E)] The following was used as an acid amplifying agent: Bn-PDT: (R)-(-)-1-benzyloxy-3-(p-tosyloxy)-2-propanol, manufactured by Aldrich

[0062] [Monofunctional or difunctional alicyclic epoxy compound (F)] The following difunctional alicyclic epoxy resin was used as the monofunctional or difunctional alicyclic epoxy compound: CEL-2021P: CELLOXIDE (registered trademark) 2021P (3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate), manufactured by Daicel Chemical Industries, Ltd.

[0063] [Preparation of Cationic Curable Composition] Various epoxy compounds, a photoacid generator, and an acid amplifier were placed in a flask in the blending ratios shown in Table 1 so that the total amount of epoxy compounds was 10 g, and the solid components were completely dissolved by stirring under heating at 110°C or less. The mixture was then cooled to room temperature, and a thermal acid generator was added and dissolved using a mix rotor. The mixture was pressure-filtered using a 3 μm SUS filter in a clean room to prepare a liquid cationic curable composition.

[0064] [Measurement of refractive index of cured film of cationically curable composition] A silicon wafer substrate and a glass substrate were cleaned using an ultraviolet ozone cleaning device (UV-208, manufactured by Technovision Co., Ltd.). A Novec 7200 (manufactured by 3M) solution containing 0.1% Optool DSX (manufactured by Daikin Industries, Ltd.) was applied to the glass substrate, and the substrate was heated at 150°C for 15 minutes to prepare a release-treated glass. Thereafter, 50 μm-thick Kapton (registered trademark) tape was attached to the silicon wafer substrate as a spacer. The composition was dropped onto the silicon wafer substrate, and the substrate was covered with release-treated glass. The cured film was then heated at 3 J / cm using a high-pressure mercury lamp (UB021-3A, manufactured by Iwasaki Electric Co., Ltd.). ２ (20 mW / cm ２ ) and exposed to light. Then, heating was performed at 60°C for 30 minutes, at 120°C for 30 minutes, and at 150°C for 30 minutes. The release-treated glass was peeled off to obtain a cured film formed on the silicon substrate. The refractive index of the cured film prepared above was measured at room temperature (approximately 23°C) using a prism coupler (manufactured by Metricon Japan, Model 2010 / M) and evaluated according to the following evaluation criteria. The results are shown in Table 1. A: The refractive index is 1.55 or higher. B: The refractive index is less than 1.55.

[0065] [Evaluation of Dark Area Curability in Dark Areas Where Acid Diffuses] A silicon wafer substrate was cleaned using an ultraviolet ozone cleaning device. A 0.5 mm thick piece of silicone rubber was used as a spacer. The composition was dropped onto the silicon wafer substrate, and half of the silicon wafer substrate was covered with release-treated glass covered with 50 μm thick Kapton (registered trademark) tape. A 365 nm bandpass filter was passed through a xenon light source lamp (MAX-302, manufactured by Asahi Spectroscopy Co., Ltd.) at 3 J / cm. ２ (20 mW / cm ２) light (Figure 1). After exposure, the film was heated at 60°C for 30 minutes and at 120°C for 30 minutes, the release-treated glass was peeled off, and the uncured areas were washed away with IPA (isopropyl alcohol). The cured film was then visually observed to see how much curing had occurred from the boundary between the irradiated and dark areas. The evaluation is shown below. The results are shown in Table 1. A: Cured 0.5 mm or more from the boundary between the irradiated and dark areas toward the dark area (cured distance on the dark area is 0.5 mm or more) B: Cured less than 0.5 mm from the boundary between the irradiated and dark areas toward the dark area (cured distance on the dark area is less than 0.5 mm)

[0066] [Preparation of a cured film of a cationically curable composition and evaluation of thermal curability in dark areas where acid cannot diffuse] A silicon wafer substrate was cleaned using an ultraviolet ozone cleaning device. A 0.5 mm thick silicone rubber spacer was used. The composition was dropped onto the silicon wafer substrate, and approximately half of the dropped and spread composition, as viewed from above, was covered with release-treated glass covered with 50 μm thick Kapton (registered trademark) tape. A xenon light source lamp (MAX-302, manufactured by Asahi Spectroscopy Co., Ltd.) was used to illuminate the film at 3 J / cm through a 365 nm bandpass filter. ２ (20 mW / cm ２ ) and irradiated with light (Figure 1). After exposure, the film was heated at 60°C for 30 minutes, 120°C for 30 minutes, and 150°C for 30 minutes, and visual inspection was performed to check whether the film had cured overall, even in the dark areas where acid would not diffuse. A: The film had cured overall, even in the dark areas where acid would not diffuse. B: The film had only cured partially (it had not cured in the dark areas where acid would not diffuse).

[0067] [Viscosity Measurement] The viscosity of the prepared cationic curable composition was measured using a rheometer (MCR302, manufactured by Anton Paar). The measurement conditions were a measurement temperature of 25°C, a rotor CP25-2, and a rotation speed of 1 rpm. The measurement results for the examples are shown in Table 1. As shown in Table 1, each of the compositions of Examples 1 to 4 had a refractive index of 1.55 or higher, good dark curability, and good thermosetting properties, resulting in overall curing upon heating at 150° C. On the other hand, none of the compositions of Comparative Examples 1 to 10 were able to satisfy any of the properties of refractive index, dark curability, or thermosetting properties.

[0068] The cationically curable composition of the present invention provides an optical member used in an adhesive or an optical transmission path, and contributes to the production and sale of adhesives and optical members used in an optical transmission path, and thus has industrial applicability.

[0069] 1 Schematic diagram showing the state of the evaluation device when irradiated with light 2 Composition 3 Spacer 4 Release-treated glass 5 Silicon wafer substrate 6 Kapton (registered trademark) tape (light-shielding part)

Claims

1. A cationic curable composition comprising a fluorene skeleton-containing epoxy compound (A) represented by the following formula [1], a monofunctional or polyfunctional epoxy compound (B) different from the fluorene skeleton-containing epoxy compound (A), a photoacid generator (C), a thermal acid generator (D), and an acid proliferator (E). (In formula [1], L １ and L ２ each independently represents a naphthalenediyl group which may have a substituent, and m and n each independently represent an integer of 0 to 10.) 2. The cation-curable composition according to claim 1, wherein the epoxy compound (B) is a monofunctional or polyfunctional aromatic epoxy compound.

3. The cation-curable composition according to claim 2, wherein the epoxy compound (B) is a bifunctional aromatic epoxy compound.

4. The cation-curable composition according to claim 1, wherein the thermal acid generator (D) is an onium salt represented by the following formula [2]. [In formula [2], R １ , R ２ , R ３ and R ４ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted heterocyclic oxy group, and R １ , R ２ , R ３ and R ４ may be bonded to each other to form a ring structure, and X － represents SbF ６ － , PF ６ － , B(C ６ F ５ )([[]] ４ － ), Ga(C ６ F ５ )([[]] ４ － ), Ga(C ６ F ５ )([[]] ２ F ２ － F ２ － ), Ga(C ６ F ５ )([[]] ３ － ), CF ３ SO ３ － or C(CF ３ SO ２ )([[]] ３ － ３ － .] 5. The cation-curable composition according to claim 1, wherein the acid generator (E) is a sulfonic acid ester compound.

6. The cation-curable composition according to claim 5, wherein the sulfonic acid ester compound is an aromatic sulfonic acid ester compound having a structure represented by the formula [3]. (In the formula [3], Ar １ represents a benzene ring, naphthalene ring or anthracene ring which may be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a hydroxy group, a nitro group, a cyano group, an amino group, a halogen group, a carboxyl group and an alkoxycarbonyl group having 1 to 6 carbon atoms, R ５ and R ６ each represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, or R ５ and R 6 may be bonded to each other to form a ring having 3 to 8 carbon atoms.) 7. The cation-curable composition according to claim 6, wherein the aromatic sulfonic acid ester compound is a toluenesulfonic acid ester compound.

8. The cationic curable composition according to claim 1, wherein the photoacid generator (C) is an onium salt having a cationic moiety represented by the following formula [4]. (In formula [4], R ７ , R ８ and R ９ are each independently a hydrogen atom, a phenylsulfanyl group, an aryl group having 6 to 10 carbon atoms, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.) 9. The cation-curable composition according to claim 2, further comprising a monofunctional or bifunctional alicyclic epoxy compound (F).

10. The cation-curable composition according to claim 9, wherein the alicyclic epoxy compound (F) is a bifunctional alicyclic epoxy compound.

11. The cation-curable composition according to claim 9, wherein the alicyclic epoxy compound (F) is a compound represented by the following formula [5]. (In formula [5], R １０ and R １１ each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms which may have an ester group or an ether group, a cyclic alkyl group having 3 to 6 carbon atoms, a linear or branched alkylene group having 1 to 6 carbon atoms, or an organic group containing a combination thereof. At this time, the linear alkyl group having 2 or more carbon atoms, the branched alkyl group having 3 or more carbon atoms, or the cyclic alkyl group may form an epoxy ring together with adjacent carbon atoms, or R １０ and R １１ may be bonded to each other to form a ring having 4 to 6 carbon atoms, and at this time, an epoxy ring may be formed together with adjacent carbon atoms constituting the ring.) 12. The cation-curable composition according to claim 1, wherein the fluorene skeleton-containing epoxy compound (A) is a compound represented by the formula [6].

13. The cation-curable composition according to claim 9, wherein the alicyclic epoxy compound (F) is at least one compound represented by the following formula [7], [8] or [9].

14. The cation-curable composition according to any one of claims 1 to 13, which is for an adhesive.

15. The cation-curable composition according to any one of claims 1 to 13, which is for an optical member used in an optical transmission path.

16. A cured product which is a polymer of the cation-curable composition according to any one of claims 1 to 13.

17. A method for producing a cured product, comprising: a photocuring step of irradiating the cation-curable composition according to any one of claims 1 to 13 with light throughout the first step to the entire step; a low-temperature heating step of heating the composition in a temperature range where the thermal acid generator (D) does not undergo an acid generation reaction; and then a high-temperature heating step of heating the composition in a temperature range higher than the temperature range of the low-temperature heating step.

18. The method for producing a cured product according to claim 17, wherein the low-temperature heating step is performed in a temperature range of 40 to 125°C, and the high-temperature heating step is performed in a temperature range of 130°C or higher.

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