Cationic curable composition

Abstract

The present invention addresses the problem of providing a cationically curable composition that can be used in optical member applications and adhesive applications, can be cured in light-irradiated portions, and can also be cured in light-non-irradiated portions in a mold having a more complicated shape. As a technical means, provided is a cationically curable composition containing: a fluorene skeleton-containing epoxy compound (A) containing a naphthalene digroup which may have a substituent; a monofunctional or bifunctional alicyclic epoxy compound (B); a photoacid generator (C); and an acid proliferation agent (D). The cationically curable composition can be cured even in a portion not irradiated by light in a mold having a complex shape.

Description

Technical Field

[0001] The present invention relates to a cation-curable composition, particularly an epoxy resin composition, and also to a cured product formed from the composition. Background Art

[0002] A photocurable resin composition has good moldability as compared with inorganic materials such as inorganic glass. Therefore, for example, in addition to optical uses, optical device uses, display device uses, mechanical component materials, electrical / electronic component materials, etc., it is also widely used in various uses such as molding materials, coatings, adhesives, etc. As a conventional photocurable resin composition, for example, a composition containing an epoxy resin and inorganic oxide particles can be cited. The light transmission path for transmitting light not only transmits light to a distance but is also used inside an optical circuit, and a light transmission path is formed on a substrate using a microfabrication technique. In such a case, not only optical properties but also good moldability is required for the resin composition in order to function as a cured product.

[0003] A photocurable epoxy resin composition is also often used as an adhesive. Sometimes a mold with a complex shape is used as an adhesive, and in this case, good formability is required.

[0004] Many epoxy resin compositions cured by light have been disclosed. For example, Patent Document 1 discloses a heat / photocurable resin composition characterized by containing an aromatic epoxy compound, an alicyclic epoxy compound and / or a hydrogenated epoxy compound, and a cationic curing catalyst. In the examples, examples of curing with heat are shown, and evaluations of transparency and refractive index are described.

[0005] Patent Document 2 shows a photosensitive epoxy resin composition for an optical waveguide having excellent high transparency and heat resistance, which contains a polyfunctional 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. In the examples, a process of exposure by UV irradiation and subsequent heating is described, and coatability, patterning resolution, etc. are evaluated.

[0006] In Patent Document 3, as an epoxy resin composition having excellent heat resistance to coloring and patterning properties, a photosensitive epoxy resin composition is shown, which contains an epoxy resin component and a photo cationic polymerization initiator, and the epoxy resin component contains an epoxy resin having a bisphenol A skeleton with 3 or more functional groups. In the examples, a process of exposure by UV irradiation and subsequent heating is described, and good heat resistance to coloring, patterning properties, and flexibility are described.

[0007] In addition, in Patent Document 4, a curable composition containing a curable compound and a cationic polymerization initiator is disclosed as a curable composition capable of forming a cured product having good heat resistance and adhesion to a substrate and having good curability. In the examples, a process of exposure and post-baking is described, and it is described that the heat resistance and the adhesion to the substrate are good.

[0008] The above-described prior art documents describe examples of curing an epoxy resin composition by irradiation with heat or light. Further, in the prior art documents, in applications where optical properties are required after curing, optical properties such as transparency and refractive index and good patterning properties as a cured product have been continuously explored.

[0009] However, in the above-described prior art documents, an acid generator or the like is not contained in the composition, and a composition that cures in a portion not exposed to light is not described.

[0010] Prior art documents

[0011] Patent documents

[0012] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-84310

[0013] Patent Document 2: Japanese Patent Application Laid-Open No. 2014-215531

[0014] Patent Document 3: Japanese Patent Application Laid-Open No. 2020-20927

[0015] Patent Document 4: Japanese Patent Application Laid-Open No. 2019-26760 Summary of the Invention

[0016] Problems to be Solved by the Invention

[0017] In the conventional photocurable resin composition shown in the above prior art, the light-irradiated portion is cured. On the other hand, the non-light-irradiated portion (hereinafter also referred to as the dark portion) does not need to be photocured. This is because, for example, when the conventional photocurable resin composition is used in a circuit board, if the non-light-irradiated portion is cured, the shape of the resist pattern deteriorates. However, it is sometimes necessary to use a mold having a complex shape in which a light-irradiated portion and a non-light-irradiated portion are formed. Further, in the case of applications as optical components and adhesives, in addition to curing the light-irradiated portion, the photocurable resin composition sometimes needs to be cured also in the non-light-irradiated portion. That is, in the case of applications as optical components and adhesives where curing is required even in the dark portion, it is not appropriate to use the conventional photocurable composition.

[0018] Therefore, the object of the cation-curable composition of the present invention is to provide a cation-curable composition having excellent curing property in the dark part, which can be cured in the dark part as well as in the light-irradiated part even in a mold having a complex shape, having a high refractive index, and being suitable for use as an adhesive or an optical component.

[0019] Means for Solving the Problem

[0020] The present inventors conducted intensive studies to solve the above problems, and as a result, found that a cation-curable composition containing a fluorene-skeleton-containing epoxy compound, a monofunctional or difunctional alicyclic epoxy compound, a photoacid generator, and an acid amplifier can solve the above problems. In particular, it was found that the photoacid generator generates an acid in the light-irradiated part, and the acid amplifier diffuses the acid to the dark part, and the acid diffused in the dark part can be used for curing, thus completing the present invention.

[0021] That is, as a first aspect of the present invention, there is provided a cation-curable composition containing a fluorene-skeleton-containing epoxy compound (A) represented by the following formula [1], a monofunctional or difunctional alicyclic epoxy compound (B), a photoacid generator (C), and an acid amplifier (D).

[0022]

[0023] (In formula [1], L 1 and L 2 each independently represent a naphthalenediyl group which may have a substituent, and m and n each independently represent an integer of 0 to 10.)

[0024] As a second aspect, there is provided the cation-curable composition according to the first aspect, wherein the acid amplifier (D) is a sulfonate compound.

[0025] As a third aspect, there is provided the cation-curable composition according to the second aspect, wherein the sulfonate compound is an aromatic sulfonate compound having a structure represented by formula [2].

[0026]

[0027] (In formula [2], 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 hydroxyl 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 1 and R 2 each represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, or R 1 and R 2They can be bonded to each other to form a ring having 3 to 8 carbon atoms.)

[0028] As a fourth aspect, it relates to the cation-curable composition described in the third aspect, wherein the aromatic sulfonate compound is a toluenesulfonate compound.)

[0029] As a fifth aspect, it relates to the cation-curable composition described in the first aspect, wherein the photoacid generator (C) is an onium salt having a cation moiety represented by the following formula [3].

[0030]

[0031] (In formula [3], R 3 , R 4 and R 5 are each independently a hydrogen atom, a phenylthio 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.)

[0032] As a sixth aspect, it relates to the cation-curable composition described in the first aspect, wherein the alicyclic epoxy compound (B) is a difunctional alicyclic epoxy compound.)

[0033] As a seventh aspect, it relates to the cation-curable composition described in the first aspect, wherein the alicyclic epoxy compound (B) is a compound represented by the following formula [4].

[0034]

[0035] (In formula [4], R 6 and R 7 are each independently a hydrogen atom, or each independently represents 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, and in this case, 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 an adjacent carbon atom, or

[0036] R 6 and R 7 can be bonded to each other to form a ring having 4 to 6 carbon atoms, and in this case, an epoxy ring can be formed together with adjacent carbon atoms constituting the ring.)

[0037] As an eighth aspect, it relates to the cation-curable composition described in the first aspect, which further comprises a monofunctional or difunctional aromatic epoxy compound (E) different from the above-mentioned epoxy compound (A) containing a fluorene skeleton.)

[0038] As a ninth aspect, it relates to the cation-curable composition described in the eighth aspect, wherein the aromatic epoxy compound (E) is a monofunctional aromatic epoxy compound.

[0039] As a tenth aspect, it relates to the cation-curable composition described in the first aspect, wherein the fluorene skeleton-containing epoxy compound (A) is a compound represented by formula [5].

[0040]

[0041] As an eleventh aspect, it relates to the cation-curable composition described in the first aspect, wherein the alicyclic epoxy compound (B) is at least one compound represented by the following formula [6], [7] or [8].

[0042]

[0043] As a twelfth aspect, it relates to the cation-curable composition according to any one of the first to eleventh aspects, which is for an adhesive.

[0044] As a thirteenth aspect, it relates to the cation-curable composition according to any one of the first to eleventh aspects, which is used for an optical component used in an optical transmission path.

[0045] As a fourteenth aspect, it relates to a cured product, which is a polymer of the cation-curable composition according to any one of the first to eleventh aspects.

[0046] Advantages of the Invention

[0047] The cation-curable composition of the present invention has excellent shadow curing property in which curing also occurs in the shadow part. Due to this property, when the cation-curable composition of the present invention is filled in a place with a complex shape, that is, a place where there are light-irradiated parts and light-non-irradiated parts, curing occurs not only in the light-irradiated parts but also in the light-non-irradiated parts. In particular, by containing an acid proliferator to continuously generate acid, shadow curing can also be achieved.

[0048] Furthermore, the cured product, which is a polymer of the cation-curable composition of the present invention, can increase the refractive index. Therefore, the cation-curable composition of the present invention can be used as a material for optical component applications and adhesive applications used in an optical transmission path. Description of the Drawings

[0049] Figure 1 It is a schematic view showing the shape of the side surface of the evaluation instrument when irradiating light in the evaluation of the shadow curing property in the examples. Detailed Description

[0050] [Cation-Curable Composition]

[0051] The cation-curable composition of the present invention contains an epoxy compound (A) having a fluorene skeleton, a monofunctional or difunctional alicyclic epoxy compound (B), a photoacid generator (C), and an acid proliferator (D). It should be noted that in this specification, the epoxy compounds containing the above (A) and (B) and other epoxy compounds described later are collectively referred to as "resin components". In addition, "monofunctional or difunctional" means containing 1 or 2 epoxy groups as functional groups.

[0052] [Epoxy compound (A) having a fluorene skeleton]

[0053] The epoxy compound (A) having a fluorene skeleton used in the present invention is a compound represented by the following formula [1].

[0054]

[0055] (In formula [1], L 1 and L 2 each independently represent a naphthalenediyl group which may have a substituent, and m and n each independently represent an integer of 0 to 10.)

[0056] As the substituent of the naphthalenediyl group (on the naphthalene ring) in L 1 and L 2 , examples include alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, and tert-butyl.

[0057] In addition, the number of substituents of the naphthalenediyl group in L 1 and L 2 is each independently 0 to 6, preferably 0 to 2, more preferably 0 or 1, and most preferably 0.

[0058] It should be noted that the types of substituents in L 1 and L 2 may be the same or different. In the case of having 2 or more substituents in the same naphthalene ring, they may be the same or different respectively.

[0059] Preferred examples of the epoxy compound (A) having a fluorene skeleton include compounds represented by the following formula [5].

[0060]

[0061] The above epoxy compound (A) having a fluorene skeleton can be a commercially available product. Examples include OGSOL (registered trademark) CG-500 and OGSOL EG-280 (manufactured by Osaka Gas Chemical Co., Ltd.).

[0062] Such an epoxide having a fluorene skeleton with a naphthalene ring may be used alone or in combination of two or more. In addition, from the viewpoints of solubility and refractive index of the resin component, for example, the above-mentioned OGSOL (registered trademark) CG-500 may be used alone.

[0063] The epoxide (A) having a fluorene skeleton may be contained in a proportion of, for example, 5 to 60 parts by mass, preferably 10 to 50 parts by mass, further preferably 15 to 45 parts by mass, and still further preferably 20 to 40 parts by mass, based on the total amount of the epoxides (100 parts by mass in total). When the blending amount of the epoxide (A) having a fluorene skeleton is too small, it is difficult to obtain a sufficient refractive index. On the contrary, when it is too large, precipitation occurs, resulting in deterioration of storage stability and reduction of film-forming properties.

[0064] [Mono-functional or di-functional alicyclic epoxide (B)]

[0065] The mono-functional or di-functional alicyclic epoxide (B) used in the present invention is not particularly limited as long as it is a compound having one or two alicyclic epoxy groups. In a preferred embodiment, the alicyclic epoxide (B) is in a liquid form. In addition, from the viewpoints of exposure sensitivity and curability, a compound having two epoxy groups introduced with an alicyclic skeleton can be cited.

[0066] As the alicyclic epoxide (B), for example, the compound represented by the following formula [4] can be cited.

[0067]

[0068] (In formula [4], R 6 and R 7 are each independently a hydrogen atom, or each independently represents 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 including 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 6 and R 7 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.)

[0069] The above-mentioned "organic group which may be a linear or branched alkyl group having 1 to 6 carbon atoms with 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" includes, for example: an ester group is bonded to an alkylene group having 1 carbon atom, and 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, there are combinations such as a case where an ether group is bonded instead of the ester group, or a case where the C-C bond of the cyclic alkyl group is further shared with another cyclic alkyl group, etc.

[0070] Examples of the above-mentioned linear or branched alkyl group having 1 to 6 carbon atoms include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl, etc.

[0071] Examples of the above-mentioned linear or branched alkylene group having 1 to 6 carbon atoms include divalent groups obtained by removing one hydrogen atom from any carbon atom of the group shown as the above-mentioned linear or branched alkyl group having 1 to 6 carbon atoms.

[0072] In addition, examples of the above-mentioned cyclic alkyl group having 3 to 6 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl.

[0073] Regarding the above-mentioned "R 6 and R 7 which 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, for example, a bonding state in which the C-C bonds of two cyclohexane rings are shared like decalin, or may form a spiro ring having a spiro atom like spiro[5.5]undecane.

[0074] In a preferred embodiment, the alicyclic epoxy compound (B) may include compounds represented by the following formulas [6], [7], or [8]. They have a low molecular weight and are liquid compounds, and are also preferred from the viewpoint of adjusting the viscosity of the composition.

[0075]

[0076] The above-mentioned alicyclic epoxy compound (B) can be a commercially available product.

[0077] As the bifunctional alicyclic epoxy compound (B), for example, diepoxy dicyclohexane (for example, manufactured by Daicel Corporation, Celloxide (registered trademark) 8000, 8010), 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexene carboxylate (for example, manufactured by Daicel Corporation, CEL-2021P: Celloxide (registered trademark) 2021P), ε-caprolactone-modified 3,4-epoxycyclohexylmethyl 3',4'-epoxycyclohexane carboxylate (for example, manufactured by Daicel Corporation, Celloxide (registered trademark) 2081), bis(3,4-epoxycyclohexylmethyl) adipate, diepoxytetrahydroindene (for example, manufactured by ENEOS Corporation, "EPOCHALIC (registered trademark) THI-DE), etc. can be cited.

[0078] In addition, for example, as the monofunctional alicyclic epoxy compound, 3,4-epoxycyclohexylmethyl methacrylate (for example, manufactured by Daicel, Cyclomer (registered trademark) M-100), 3,4-epoxycyclohexylmethyl methacrylate, 1,2-epoxy-4-vinylcyclohexane (for example, manufactured by Daicel, Celloxide (registered trademark) 2000), 1,2,8,9-diepoxylimonene (for example, manufactured by Daicel, Celloxide (registered trademark) 3000), etc. can be used.

[0079] The alicyclic epoxy compound (B) can contain, for example, 10 parts by mass to 80 parts by mass, preferably 15 parts by mass to 75 parts by mass, more preferably 20 parts by mass to 70 parts by mass, and still more preferably 25 parts by mass to 65 parts by mass based on the total amount of the epoxy compounds (total 100 parts by mass). When the blending amount of the alicyclic epoxy compound (B) is too small, the viscosity becomes high and the operation becomes difficult. On the contrary, when it is too large, it is difficult to obtain a sufficient refractive index.

[0080] [Photoacid generator (C)]

[0081] The cation-curable composition of the present invention contains a photoacid generator (C).

[0082] Specific examples of the photoacid generator (C) include onium salts such as iodonium salts, sulfonium salts, phosphonium salts, and selenonium salts, metallocene complex compounds, iron arene complex compounds, disulfone-based compounds, sulfonic acid derivative compounds, triazine-based compounds, acetophenone derivative compounds, diazomethane-based compounds, etc.

[0083] Among the above-mentioned onium salts, as iodonium salts, for example, 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, 4-methoxyphenyl(phenyl)iodonium and other diaryliodonium chlorides, bromides, methanesulfonates, toluenesulfonates, trifluoromethanesulfonates, tetrafluoroborates, tetrakis(pentafluorophenyl)borates, hexafluorophosphates, hexafluoroarsenates, hexafluoroantimonates and other diaryliodonium salts can be cited.

[0084] As the above-mentioned sulfonium salt, from the viewpoints of high thermal stability and acid generation efficiency based on ultraviolet irradiation, it is preferably a photoacid generator of a sulfonium salt having a cation moiety represented by the following formula [3].

[0085]

[0086] (In formula [3], R 3 , R 4 and R 5 are each independently a hydrogen atom, a phenylthio 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.)

[0087] As the sulfonium salt having a cation moiety represented by the following formula [3], for example, 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, tris(4-(phenylthio)phenyl)sulfonium and other triarylsulfonium chlorides, bromides, trifluoromethanesulfonates, tetrafluoroborates, hexafluorophosphates, hexafluoroarsenates, hexafluoroantimonates and other triarylsulfonium salts can be cited.

[0088] As the above-mentioned phosphonium salt, for example, tetraphenylphosphonium, ethyltriphenylphosphonium, tetrakis(p-methoxyphenyl)phosphonium, ethyltris(p-methoxyphenyl)phosphonium, benzyltriphenylphosphonium and other triarylphosphonium or tetraarylphosphonium chlorides, bromides, tetrafluoroborates, hexafluorophosphates, hexafluoroantimonates and other arylphosphonium salts can be cited.

[0089] As the above-mentioned selenonium salt, triphenylselenium hexafluorophosphate and other triarylselenonium salts can be cited.

[0090] As the above-mentioned iron-arene complex compound, for example, bis(η5-cyclopentadienyl)(η6-isopropylbenzene)iron(II) hexafluorophosphate and the like can be cited.

[0091] Among them, as the photoacid generator, onium salts such as iodonium salts and sulfonium salts can be preferably used. Commercially available products can be used, and for example, triaryl sulfonium salts such as CPI-310FG, CPI-310B, CPI-200K, and CPI-101A can be cited.

[0092] These photoacid generators (C) can be used alone or in combination of two or more.

[0093] Based on 100 parts by mass of the total mass of the above-mentioned epoxy compound (resin component), the photoacid generator (C) usually can contain, for example, 0.05 parts by mass to 10 parts by mass, preferably can contain 0.1 parts by mass to 5 parts by mass, further can contain 0.15 parts by mass to 3 parts by mass, and more preferably is 0.2 parts by mass to 2 parts by mass. When the compounding amount of the photoacid generator (C) is less than 0.05 parts by mass, it is possible that the curing reaction cannot proceed sufficiently. In addition, when it exceeds 10 parts by mass, the degree of polymerization of the polymer decreases, and it may become brittle and prone to cracking.

[0094] [Acid proliferator (D)]

[0095] The cationic curable composition of the present invention contains an acid proliferator (D).

[0096] The acid proliferator (D) of the present invention has the property of decomposing due to the action of an acid and continuously generating an acid, so it is also cured in the non-irradiated part (dark part). The cationic curable composition of the present invention is cured by the acid generated by the photoacid generator and the acid generated by the acid proliferator in the light-irradiated part. Moreover, in the non-light-irradiated part (dark part), due to the action of the acid generated by the light-irradiated part, the acid proliferator further continuously generates an acid, thereby curing.

[0097] As such an acid proliferator, a sulfonate compound (a compound containing a sulfonate derivative) can be used, and further an aromatic sulfonate compound (a compound containing an aromatic sulfonate derivative) can be used.

[0098] There is no particular limitation on the sulfonate compound used. For example, an alkyl sulfonate compound having an alkyl group with 1 to 10 carbon atoms can be cited. The above-mentioned alkyl group with 1 to 10 carbon atoms can be substituted with a group selected from phenyl, naphthyl, alkoxy, etc. In addition, an aromatic sulfonate compound having an aromatic hydrocarbon ring such as a benzene ring, a naphthalene ring, an anthracene ring, a fluorene ring, and a tetracene ring can be cited. As the ester part of the sulfonate compound, it can be either an alkyl ester or an aryl ester.

[0099] Examples of the alkyl group having 1 to 10 carbon atoms include linear or branched alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 1-methyl-n-butyl, 2-methyl-n-butyl, 3-methyl-n-butyl, 1,1-dimethyl-n-propyl, 1,2-dimethyl-n-propyl, 2,2-dimethyl-n-propyl, 1-ethyl-n-propyl, n-hexyl, 1-methyl-n-pentyl, 2-methyl-n-pentyl, 3-methyl-n-pentyl, 4-methyl-n-pentyl, 1,1-dimethyl-n-butyl, 1,2-dimethyl-n-butyl, 1,3-dimethyl-n-butyl, 2,2-dimethyl-n-butyl, 2,3-dimethyl-n-butyl, 3,3-dimethyl-n-butyl, 1-ethyl-n-butyl, 2-ethyl-n-butyl, 1,1,2-trimethyl-n-propyl, 1,2,2-trimethyl-n-propyl, 1-ethyl-1-methyl-n-propyl, and 1-ethyl-2-methyl-n-propyl, etc.

[0100] Specific examples of the alkyl sulfonate compound include, for example, 1,4-bis(methanesulfonyloxy)cyclohexane, 1,4-bis(2,2,2-trifluoroethanesulfonyloxy)cyclohexane, 1,4-bis(trifluoromethanesulfonyloxy)cyclohexane, 1,3-bis(methanesulfonyloxy)cyclohexane, 1,3-bis(2,2,2-trifluoroethanesulfonyloxy)cyclohexane, 1,3-bis(trifluoromethanesulfonyloxy)cyclohexane, and 1,3-bis(2,2,2-trifluoroethanesulfonyloxy)propane, etc.

[0101] From the viewpoints of storage stability and the like, in the cationic curable composition of the present invention, it is preferable that the sulfonate compound used in the present composition is not a compound that is easily decomposed by heat. Therefore, from the viewpoint of the thermal decomposition temperature, it is preferable to use the aromatic sulfonate compound represented by the formula [2], and more preferably an aromatic sulfonate compound containing a tolylsulfonate having Ar 1 as a tolyl group.

[0102]

[0103] (In the formula [2], 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 hydroxyl 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 1 and R 2 each represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, or R 1 and R 2 may be bonded to each other to form a ring having 3 to 8 carbon atoms.)

[0104] As specific examples of the aromatic sulfonate compound containing a toluenesulfonate, for example, 1,3-bis(p-toluenesulfonyloxy)propane, 1,2-bis(p-toluenesulfonyloxy)ethane, 1,4-di-o-toluenesulfonyl-2,3-o-isopropylidene D-threitol, triethylene glycol dimethanesulfonate, 2,3-dihydroxybutane-1,4-diyl bis(p-toluenesulfonate), tetrakis(p-toluenesulfonyloxymethyl)methane, 1,2-propanediol di-p-toluenesulfonate, 1,2,4-trimethylbenzenesulfonic acid butanetriol ester, 2,3-butanediol di-p-toluenesulfonate, diethylene glycol di-p-toluenesulfonate, N,N-bis(2-(toluenesulfonyloxy)ethyl)toluene-4-sulfonamide, 1,3-adamantanediol di-p-toluenesulfonate, 1-benzyloxy-3-(p-toluenesulfonyloxy)-2-propanol, 4,4'-bis(p-toluenesulfonyloxy) isopropylidene cyclohexane, 1,3-bis(p-toluenesulfonyloxy)cyclohexane, 1,4-bis(p-toluenesulfonyloxy)cyclohexane, (R)-(-)-1-benzyloxy-3-(p-toluenesulfonyloxy)-2-propanol, cyclohexyl p-toluenesulfonate, pinanediol mono(p-toluenesulfonate), cyclopentyl p-toluenesulfonate, 1-(p-toluenesulfonyloxy)-4-trifluoromethanesulfonyloxycyclohexane, 1-(p-toluenesulfonyloxy)-4-(3,3,3-trifluoroethanesulfonyloxy)cyclohexane and other aromatic sulfonate compounds of toluenesulfonic acid compounds can be cited, but are not limited to these. In addition, the acid generator can be used alone or in combination of two or more.

[0105] These acid generators (D) can be used alone or in combination of two or more.

[0106] Based on 100 parts by mass of the total mass of the above epoxy compounds (resin components), the acid generator (D) generally may contain, for example, 0.1 part by mass to 20 parts by mass, preferably may contain 0.3 part by mass to 15 parts by mass, further may contain 0.5 part by mass to 10 parts by mass, and more preferably 1.0 part by mass to 5 parts by mass. When the blending amount of the acid generator (D) is less than 0.1 part by mass, the curing reaction may not proceed sufficiently in the dark part. In addition, when the blending amount of the acid generator (D) exceeds 20 parts by mass, the degree of polymerization of the polymer decreases, and it may become brittle and prone to cracking.

[0107] In addition, as the acid generated from the photoacid generator (C) and the acid generator (D), an acid generally referred to as a strong acid is preferred. For example, as the acid generated from the photoacid generator (C), preferably (C 6 F 5 ) 4 GaH, {(CF 3 ) 2 C 6 H 3} 4 GaH, (CF3 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 PF 4 H, {(CF 3 ) 2 CF} 3 PF 3 H, etc., as the acid generated by the acid generator (D), preferably CF 3 CF 2 CF 2 CF 2 SO 3 H, CF 3 CF 2 CF 2 SO 3 H, CF 3 CF 2 SO 3 H, CH 3 (C 6 H 6 )SO 3 H, CF 3 SO 3 H, H 2 SO 4 etc., but the types of acids are not limited to these.

[0108] [Monofunctional or bifunctional aromatic epoxide (E)]

[0109] In addition, the present invention may include a monofunctional or difunctional aromatic epoxy compound (E) different from the aforementioned epoxy compound (A). From the viewpoints of exposure sensitivity and curability, in a preferred embodiment, the aromatic epoxy compound (E) may be a compound having two epoxy groups. For example, a compound having a basic skeleton of bisphenol may be used, and among them, an epoxy compound having a bisphenol A skeleton or a bisphenol F skeleton is preferred.

[0110] The aromatic epoxy compound (E) may be a commercially available product.

[0111] As the difunctional aromatic epoxy compound (E), for example, jER (registered trademark) 806 manufactured by Mitsubishi Chemical Corporation, which is a bisphenol F type epoxy compound, and jER (registered trademark) 828 manufactured by Mitsubishi Chemical Corporation, which is a bisphenol A type epoxy compound, can be cited.

[0112] In addition, as the monofunctional aromatic epoxy compound (E), phenyl glycidyl ether (for example, manufactured by Nagase ChemteX Corporation, DENACOL (registered trademark) EX-141), phenol (EO) 5 glycidyl ether (for example, manufactured by Nagase ChemteX Corporation, DENACOL (registered trademark) EX-145), p-tert-butylphenyl glycidyl ether (for example, manufactured by Nagase ChemteX Corporation, DENACOL (registered trademark) EX-146), etc. can be cited.

[0113] Relative to the total amount (100 parts by mass) of the epoxy compound, the aromatic epoxy compound (E) preferably contains, for example, 1 part by mass to 60 parts by mass, and may further contain 2 parts by mass to 55 parts by mass, 5 parts by mass to 50 parts by mass, and more preferably 8 parts by mass to 45 parts by mass. When the blending amount of the aromatic epoxy compound (E) is too small, a sufficient refractive index is difficult to obtain and a uniform film is difficult to obtain. On the contrary, when it is too large, there is a possibility of reducing the curability.

[0114] [Other epoxy compounds]

[0115] Within the range that does not impair the effects of the present invention, the cation-curable composition of the present invention may further contain other epoxy compounds other than the epoxy compounds (A), (B), and (E) described above.

[0116] For example, heterocyclic-containing epoxy compounds such as triglycidyl isocyanurate and aliphatic epoxy compounds can be cited. As specific examples of the above-mentioned aliphatic epoxy compounds, monofunctional epoxy compounds such as glycidyl ethers of aliphatic alcohols and glycidyl esters of alkyl carboxylic acids, and polyglycidyl ethers of aliphatic polyols or their alkylene oxide adducts can be cited. As these representative specific compounds, allyl glycidyl ether can be cited; glycidyl ethers of monohydric alcohols such as butyl glycidyl ether, 2-ethylhexyl glycidyl ether, and glycidyl ether of C12-C13 mixed alcohols; 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, triglycidyl ether of glycerol, triglycidyl ether of trimethylolpropane, tetraglycidyl ether of sorbitol, hexaglycidyl ether of dipentaerythritol, diglycidyl ether of polyethylene glycol, diglycidyl ether of polypropylene glycol, etc.; and polyglycidyl ethers of polyether polyols which are alkylene oxide adducts of one or more of aliphatic polyols such as propylene glycol, trimethylolpropane, and glycerol.

[0117] These other epoxy compounds can be contained, for example, in a proportion of 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.

[0118] [Organic solvent]

[0119] The cation-curable composition of the present invention can be blended with an organic solvent.

[0120] When the prepared composition has a low viscosity, it is not necessary to add an organic solvent, and good film formation can be carried out. In this case, since there is no solvent, it is also advantageous that there is no need for a process such as heat treatment to volatilize the organic solvent after film formation. In addition, by not blending an organic solvent, concerns such as health damage caused by operator suction and corrosion of peripheral equipment that may occur during the volatilization of the organic solvent can be significantly reduced.

[0121] The cation-curable composition of the present invention becomes a composition with a lower viscosity, so the blending of an organic solvent is not essential. Even if an organic solvent is contained, the above effects of the present invention will not be lost, and it can be added in any proportion.

[0122] The organic solvents that can be used in the present invention are not particularly limited as long as they are commonly used organic solvents in the technical field. However, if solvents with extremely high polarity or low polarity such as water and hydrocarbon solvents such as hexane are used, precipitation, phase separation, etc. will occur, so it is preferably controlled. In addition, when a large amount of organic solvent is added, it may not be possible to ensure a sufficient film thickness during film formation, so attention needs to be paid.

[0123] [Other additives]

[0124] The cationic curable composition of the present invention may contain other additives commonly used in the art within the range that does not impair the effects of the present invention. As other additives, for example, thermal acid generators, antireflection agents, ultraviolet absorbers, antioxidants, light stabilizers, sensitizers, surfactants, crosslinking agents, leveling agents, silane coupling agents, etc. can be cited.

[0125] When using these other additives, generally, relative to 100 parts by mass of the total mass of the epoxy compounds (resin components), they can be blended in a proportion of 10 parts by mass or less, 5 parts by mass or less, or 3 parts by mass or less.

[0126] [Preparation of Cationic Curable Composition]

[0127] As described later, the aforementioned cationic curable composition of the present invention can be suitably used as an adhesive and a material for forming an optical transmission path. The method for preparing the cationic curable composition in the form of this embodiment is not particularly limited.

[0128] As the preparation method, for example, a method of adding the above components (A), (B), (C), and (D), and component (E) and other epoxy compounds or other additives as needed and mixing them to form a uniform solution, or a method of using a conventional organic solvent in addition to these components can be cited.

[0129] In the cationic curable composition of the present invention, when the total mass of the epoxy compounds is set to 100 parts by mass, the fluorene skeleton-containing epoxy compound (A) can be in a proportion of 10 to 40 parts by mass, the alicyclic epoxy compound (B) can be in a proportion of 20 to 70 parts by mass, and the aromatic epoxy compound (E) can be in a proportion of 5 to 50 parts by mass. Relative to 100 parts by mass of the total mass of the above epoxy compounds (resin components), the photoacid generator (C) can be in a proportion of 0.1 to 5 parts by mass, the acid proliferator (D) can be in a proportion of 0.1 to 20 parts by mass, and other additives can be in a proportion of 0 to 10 parts by mass.

[0130] When using the above organic solvent, the proportion of the solid components in the cationic curable composition is not particularly limited as long as each component is uniformly dissolved in the organic solvent, for example, it is 60% by mass or more, or 70% by mass or more. It is preferable to make the proportion of the solid components in the composition, for example, 75% by mass to 99% by mass. Here, the solid components are substances obtained by removing the organic solvent components from all the components of the cationic curable composition.

[0131] In addition, the cationic curable composition is preferably filtered using a filter with a pore size of 0.05 to 5 μm and then used.

[0132] 〔Viscosity〕

[0133] The cationic curable composition of the present invention preferably has a viscosity with excellent workability during preparation.

[0134] For example, the viscosity of the above cationic curable composition can be 10 to 10,000 mPa·s at 25°C, preferably 20 to 5,000 mPa·s, more preferably 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 does not diffuse, and it may not be possible to cure the dark part. If the viscosity is lower than 10 mPa·s, sometimes the above composition flows and does not stay on the bonding surface, resulting in poor operability.

[0135] 〔Adhesive〕

[0136] The adhesive of the present invention contains a cured product of the above cationic curable composition and is preferably formed from a cured product of the cationic curable composition. The cured product of the cationic curable composition of the present invention has characteristics of high heat resistance and high refractive index and can be suitably used as an adhesive for optical components, etc. In particular, since the cationic curable composition of the present invention has dark part curability, it is useful as an adhesive for bonding components having a shape that produces a dark part during curing by light irradiation.

[0137] 〔Light transmission path〕

[0138] The light transmission path of the present invention contains a cured product of the above cationic curable composition and is preferably formed from a 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 composed of a core and a cladding that surrounds the entire outer periphery thereof and has a refractive index smaller than that of the core. The above core layer or cladding can be formed from a cured product of the cationic curable composition.

[0139] [Examples]

[0140] Hereinafter, examples and comparative examples are listed to more specifically illustrate the present invention, but the present invention is not limited to the following examples.

[0141] It should be noted that the compounds and their abbreviated symbols used in the examples, etc. are as follows.

[0142] [Epoxy compound (A) containing a fluorene skeleton]

[0143] As the epoxy compound (A) containing a fluorene skeleton, a bicyclic epoxy compound containing a fluorene skeleton is used.

[0144] CG-500: OGSOL (registered trademark) CG-500, manufactured by Osaka Gas Chemical Co., Ltd. (Osaka Gas Chemical Co., Ltd.)

[0145]

[0146] [Mono-functional or difunctional alicyclic epoxy compound (B)]

[0147] As the mono-functional or difunctional alicyclic epoxy compound (B), a difunctional alicyclic epoxy resin was used.

[0148] THI-DE: EPOCHALIC (registered trademark) THI-DE, manufactured by ENEOS Corporation

[0149] CEL-2021P: CELLOXIDE (registered trademark) 2021P (3’,4’-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate), manufactured by Daicel Chemical Industries, Ltd.

[0150]

[0151] [Photoacid generator (C)]

[0152] As the photoacid generator (C), the following substances were used.

[0153] CPI-310FG: Triarylsulfonium salt type photoacid generator, manufactured by San-Apro Ltd.

[0154] CPI-200K: Sulfonium salt type photoacid generator (50% Propylene carbonate solution), manufactured by San-Apro Ltd.

[0155] CPI-310B: Triarylsulfonium salt type photoacid generator, manufactured by San-Apro Ltd.

[0156]

[0157] [Acid proliferator (D)]

[0158] The following was used as the acid proliferator (D).

[0159] Bn-PDT: (R)-(-)-1-benzyloxy-3-(p-toluenesulfonyloxy)-2-propanol, manufactured by Aldrich

[0160]

[0161] [Aromatic epoxy compound (E)]

[0162] As the aromatic epoxy compound (E), a difunctional aromatic epoxy compound was used.

[0163] jER806: Bisphenol F type epoxy resin, manufactured by Mitsubishi Chemical Corporation

[0164]

[0165] As the aromatic epoxy compound (E), a monofunctional aromatic epoxy compound is used.

[0166] EX-141: Denacol (registered trademark) EX-141 (phenyl glycidyl ether), manufactured by Nagase ChemteX Corporation

[0167]

[0168] [Preparation of cationic curable composition]

[0169] With the total amount of the epoxy compounds being 10 g, various epoxy compounds, a photoacid generator, and an acid proliferator were placed in a flask in the mixing ratio shown in Table 1, and stirred under heating at 110 °C or lower to completely dissolve the solid components. Then, it was cooled to room temperature, the acid proliferator was added, and it was dissolved using a hot mixing rotor. Pressurized filtration was performed using a 3-μm diameter SUS filter in a clean room to prepare a liquid cationic curable composition.

[0170] [Measurement of refractive index of cured film of cationic curable composition]

[0171] A silicon wafer substrate and a glass substrate were cleaned using an ultraviolet ozone cleaning device (manufactured by TechnoVision Corporation, UV-208). A solution of Novec 7200 (manufactured by 3M) containing 0.1% OPTOOL DSX (manufactured by Daikin Industries) was coated on the glass substrate and heated at 150 °C for 15 minutes to produce a demolding-treated glass. Then, a 50-μm thick Kapton (registered trademark) tape as a spacer was pasted on the silicon wafer substrate. The above composition was dropped onto this silicon wafer substrate, the demolding-treated glass was covered, and it was directly exposed using a high-pressure mercury lamp (UB021-3A, manufactured by Iwasaki Electric Co., Ltd.) at 3 J / cm 2 (20 mW / cm 2 ). After heating at 60 °C for 30 minutes, the demolding-treated glass was peeled off, and the refractive index of the cured film was measured at room temperature (about 23 °C) using a prism coupler (manufactured by Metricon Japan Co., Ltd., model 2010 / M), and evaluated according to the following evaluation criteria. The results obtained are shown in Table 1.

[0172] A: The refractive index is 1.55 or more.

[0173] B: The refractive index is less than 1.55.

[0174] [Evaluation of curing property in the dark part]

[0175] Clean the silicon wafer substrate using an ultraviolet ozone cleaning device. As a spacer, use silicone rubber with a thickness of 300 μm. Drop the above composition onto the silicon wafer substrate, cover it with a release-treated glass half-covered with a 50-μm-thick Kapton (registered trademark) tape, and irradiate it with a xenon light source lamp (MAX-302, manufactured by Asahi Spectra Co., Ltd.) through a 365-nm band-pass filter at 3 J / cm 2 (20 mW / cm 2 ). Light( Figure 1 ). After exposure, heat it at 60 °C for 30 minutes and then at 120 °C for 30 minutes. Peel off the release-treated glass and rinse the uncured part with IPA. Then, in the cured film, visually observe the degree of curing starting from the boundary line between the irradiated part and the dark part. The evaluation is as follows. The obtained results are shown in Table 1.

[0176] A: Cured more than 1 mm from the boundary line between the irradiated part and the dark part toward the dark part

[0177] (The curing distance on the dark part side is more than 1 mm)

[0178] B: Cured less than 1 mm from the boundary line between the irradiated part and the dark part toward the dark part

[0179] (The curing distance on the dark part side is less than 1 mm)

[0180] [Viscosity measurement]

[0181] For the prepared cationic curable composition, measure the viscosity using a rheometer (manufactured by Anton Paar, MCR302). As the measurement conditions, measure at a measurement temperature of 25 °C, a rotor of CP25-2, and a rotation speed of 1 rpm. The measurement results of the examples are shown in Table 1.

[0182]

[0183] As shown in Table 1, the compositions of Examples 1 to 8 obtained results with a refractive index of 1.55 or more and good curing property in the dark part. On the other hand, the results of the compositions of Comparative Examples 1 to 12 could not meet any of the properties of refractive index and curing property in the dark part. It should be noted that in Comparative Examples 7 to 12 without the epoxy compound (A), the refractive index of the cured product did not meet the qualified standard, and the evaluation of the curing property in the dark part was omitted.

[0184] Industrial applicability

[0185] The cation-curable composition of the present invention provides adhesives and optical components for optical transmission paths, contributing to the manufacture and sale of adhesives and optical components for optical transmission paths, and thus has industrial availability.

[0186] Explanation of Reference Numerals

[0187] 1 is a schematic view showing the shape of the side surface of the evaluation instrument when irradiating light.

[0188] 2 Composition

[0189] 3 Spacer

[0190] 4 Demolding-treated glass

[0191] 5 Silicon wafer substrate

[0192] 6 KAPTON (registered trademark) tape (light-shielding portion).

Claims

1. A cation-curable composition comprising a fluorene-skeleton-containing epoxy compound (A) represented by the following formula [1], a monofunctional or difunctional alicyclic epoxy compound (B), a photoacid generator (C), and an acid proliferator (D). In formula [1], L 1 and L 2 each independently represent a naphthalenediyl 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 acid proliferator (D) is a sulfonate compound.

3. The cation-curable composition according to claim 2, wherein, the sulfonate compound is an aromatic sulfonate compound having a structure represented by formula [2], In formula [2], Ar 1 represents a benzene ring, naphthalene ring or anthracene ring which may be substituted by 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 hydroxyl 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 1 and R 2 each represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, or R 1 and R 2 may be bonded to each other to form a ring having 3 to 8 carbon atoms.

4. The cation-curable composition according to claim 3, wherein, the aromatic sulfonate compound is a toluenesulfonate compound.

5. The cation-curable composition according to claim 1, wherein, the photoacid generator (C) is an onium salt having a cationic moiety represented by the following formula [3], In formula [3], R 3 , R 4 and R 5 are each independently a hydrogen atom, a phenylthio 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.

6. The cation-curable composition according to claim 1, wherein, the alicyclic epoxy compound (B) is a difunctional alicyclic epoxy compound.

7. The cation-curable composition according to claim 1, wherein, the alicyclic epoxy compound (B) is a compound represented by the following formula [4], In formula [4], R 6 and R 7 are each independently a hydrogen atom, or each independently represents 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 comprising a combination thereof. In this case, 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 an adjacent carbon atom, or R 6 and R 7 can bond to each other to form a ring having 4 to 6 carbon atoms, and at this time, an epoxy ring can be formed together with adjacent carbon atoms constituting the ring.

8. The cation-curable composition according to claim 1, further comprising a monofunctional or difunctional aromatic epoxy compound (E) different from the fluorene-skeleton-containing epoxy compound (A).

9. The cation-curable composition according to claim 8, wherein, the aromatic epoxy compound (E) is a monofunctional aromatic epoxy compound.

10. The cation-curable composition according to claim 1, wherein, the fluorene-skeleton-containing epoxy compound (A) is a compound represented by formula [5], 11. The cation-curable composition according to claim 1, wherein, the alicyclic epoxy compound (B) is at least one compound represented by the following formula [6], [7] or [8], 12. The cation-curable composition according to any one of claims 1 to 11 is for use as an adhesive.

13. The cation-curable composition according to any one of claims 1 to 11 is used for an optical component used in an optical transmission path.

14. A cured product which is a polymer of the cation-curable composition according to any one of claims 1 to 11.

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