Acid generator, curable composition containing said acid generator, and cured product thereof

Abstract

Provided are: an acid generator which has excellent solubility in a cationic curable compound; and a curable composition which can be quickly cured by heat treatment and which forms a cured product having excellent insulating properties. This acid generator contains a salt (1) of a cation represented by formula (c-1) and an anion represented by formula (a-1). In formula (c-1), R1, R2, and R3 may be the same or different and each represents a C1-6 alkyl group. In formula (a-1), Rf11 represents a fluoroalkyl group, and s represents an integer of 1-5. In formula (a-2), Rf12 represents a fluoroalkyl group, a fluoroaryl group, or a fluoroalkyl-substituted aryl group, t represents an integer from 1 to 4, and u represents 0 or 1. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a novel acid generator, a curable composition containing the acid generator, and a cured product thereof. Background Art

[0002] Conventionally, as a compound that generates an acid by heating and cures a cationic curable compound (so-called thermal acid generator), for example, benzylanilinium salt is known.

[0003] Patent Document 1 describes a sealing agent for an organic EL display element, which contains a benzylaniline ammonium salt and a cationic polymerizable compound. The benzylaniline ammonium salt has a cationic portion represented by the following formula and a selected from AsF6 - 、SbF6 - PF6 - and (C6F5)4B - The anion part in .

[0004] [Chemistry 3]

[0005]

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2016-51602 Summary of the invention

[0009] Problems to be solved by the invention

[0010] Semiconductor devices are required to have electrical reliability and must avoid the incorporation of ionic substances. Therefore, in resin sealing packages of semiconductor elements such as organic EL display elements, electrical insulation is required for the resin cured product (cured product of the sealant) used for sealing.

[0011] However, if the acid generator is contained in the sealant without being dissolved, not only the desired curing properties cannot be obtained, but also insoluble components of the acid generator are likely to remain in the cured product of the sealant. If the insoluble components of the acid generator are contained in the cured product of the sealant, the insoluble components may cause the electrical characteristics of the semiconductor element to deteriorate.

[0012] Furthermore, when the acid generator is contained in the sealant in an undissolved state, the acid generator is unevenly present in the cured product of the sealant, and such a cured product is prone to coloration when exposed to a high temperature environment. Coloration is a major problem when used in optical materials.

[0013] In order to solve the above problems, it is important to dissolve the acid generator completely in the resin. However, the benzylanilinium salt described in Patent Document 1 is difficult to dissolve in the resin, and it is extremely difficult to confirm that no insoluble components remain. Therefore, sufficient dissolution operation is required to ensure the dissolution of the benzylanilinium salt. As a result, a large amount of time is spent in the dissolution operation, and the operation efficiency is poor.

[0014] Therefore, an object of the present invention is to provide an acid generator having excellent solubility in a cationic curable compound.

[0015] Another object of the present invention is to provide a curable composition that cures rapidly by heat treatment to form a cured product having excellent insulating properties.

[0016] Another object of the present invention is to provide a curable composition that cures rapidly by heat treatment to form a cured product having excellent resistance to thermal yellowing.

[0017] Means for solving problems

[0018] The present inventors have conducted intensive studies to solve the above-mentioned problems and have found the following.

[0019] 1. The salt (1) of a cation represented by the following formula (c-1) and an anion represented by the following formula (a-1) or (a-2) has excellent solubility in the cationic curable compound;

[0020] 2. Although the resin is easily yellowed by acid, the acid generated by thermal decomposition of the above-mentioned salt (1) is less likely to cause yellowing of the resin;

[0021] 3. When the salt (1) is used, a curable composition without residual insoluble components of the acid generator can be efficiently produced;

[0022] 4. The curable composition using the above salt (1) as an acid generator has excellent curability and can form a cured product with excellent insulating properties;

[0023] 5. The curable composition using the salt (1) as an acid generator can form a cured product having excellent resistance to heat yellowing because uneven distribution of the acid generator is suppressed (in other words, the acid generator is uniformly contained).

[0024] The present invention has been accomplished based on these findings.

[0025] That is, the present invention provides an acid generator comprising a salt (1) of a cation represented by the following formula (c-1) and an anion represented by the following formula (a-1) or (a-2).

[0026] [Chemistry 1]

[0027]

[0028] (In formula (c-1), R 1 , R 2 , R 3 are the same or different and represent an alkyl group having 1 to 6 carbon atoms. f 11 represents a fluoroalkyl group, and s represents an integer of 1 to 5. In formula (a-2), R f 12 represents a fluoroalkyl group, a fluoroaryl group, or a fluoroalkyl-substituted aryl group, t represents an integer of 1 to 4, and u represents 0 or 1.

[0029] The present invention also provides the acid generator described above, further comprising a salt (2) of a cation represented by the following formula (c-2) and the anion described above, wherein the content of the salt (2) is 0.001 wt % or more and 5 wt % or less.

[0030] [Chemistry 2]

[0031]

[0032] (In formula (c-2), n represents an integer greater than or equal to 1. R 1 , R 2 , R 3 Same as above.)

[0033] The present invention also provides a curable composition comprising the above-mentioned acid generator and a cationic curable compound.

[0034] The present invention also provides a cured product, which is a cured product of the curable composition.

[0035] Effects of the Invention

[0036] The acid generator of the present invention has excellent solubility in a cationic curable compound.

[0037] Therefore, by mixing the acid generator and the cationic curable compound and stirring them for a short time, the acid generator can be completely dissolved, and the curable composition can be produced efficiently.

[0038] In addition, the curable composition obtained by the above method is excellent in storage stability, and can suppress precipitation of the acid generator over time.

[0039] Furthermore, the curable composition can be rapidly cured by heat treatment to form a cured product having excellent insulating properties.

[0040] In addition, the cured product of the curable composition contains the acid generator uniformly or suppresses uneven distribution of the acid generator. f11 ) s PF 6-s or H[R f 12 (O) u ] t G JZ 4-t ) has the property of not easily causing yellowing of the resin. Therefore, the above-mentioned cured product can suppress coloring even when exposed to a high temperature environment and can stably maintain transparency for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is the salt (1-1a) obtained in Example 1 1 A graph showing the results of H-NMR measurement.

[0042] Figure 2 is the salt (1-1a) obtained in Example 1 19 A graph showing the results of F-NMR measurement.

[0043] Figure 3 is the salt (1-2a) obtained in Example 21 1 A graph showing the results of H-NMR measurement.

[0044] Figure 4 is the salt (1-2a) obtained in Example 21 19 A graph showing the results of F-NMR measurement. DETAILED DESCRIPTION

[0045] [Acid generator]

[0046] The acid generator of the present invention comprises a salt (1) of a cation represented by the following formula (c-1) and an anion represented by the following formula (a-1) or (a-2).

[0047] [Chemistry 4]

[0048]

[0049] The salt (1) includes a salt (1-1) of a cation represented by the formula (c-1) and an anion represented by the formula (a-1) and a salt (1-2) of a cation represented by the formula (c-1) and an anion represented by the formula (a-2).

[0050] In formula (c-1), R 1 , R 2 , R 3 The same or different groups represent an alkyl group having 1 to 6 carbon atoms.

[0051] In formula (a-1), R f 11represents a fluoroalkyl group, and s represents an integer of 1-5.

[0052] In formula (a-2), R f 12 represents a fluoroalkyl group, a fluoroaryl group, or a fluoroalkyl-substituted aryl group, t represents an integer of 1 to 4, and u represents 0 or 1.

[0053] As R 1 , R 2 , R 3 Examples of the alkyl group having 1 to 6 carbon atoms include linear or branched alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl and hexyl.

[0054] As R 1 , preferably C 1-4 alkyl.

[0055] As R 2 , R 3 , preferably C 1-3 Alkyl, particularly preferably C 1-2 alkyl.

[0056] As R 1 , R 2 , R 3 Among them, from the viewpoint of excellent solubility, the combination of the following [1] to [3] is preferred.

[0057] [1] R 1 Methyl, R 2 , R 3 Same or different and C 2-4 alkyl;

[0058] [2] R 1 C 2-4 Alkyl, R 2 , R 3 is methyl;

[0059] [3] R 1 , R 2 , R 3 All are methyl.

[0060] R f 11 The fluoroalkyl group in the above is a group in which at least one of the hydrogen atoms bonded to the alkyl group is substituted with a fluorine atom. Examples of the above alkyl group include a linear or branched alkyl group having 1 to 5 carbon atoms (preferably 1 to 3 carbon atoms, particularly preferably 2 to 3 carbon atoms, and most preferably 2 carbon atoms).

[0061] As R f 11The fluoroalkyl group in the present invention is preferably a perfluoroalkyl group (=a group in which all hydrogen atoms bonded to the alkyl group are replaced by fluorine atoms), and more preferably a perfluoroalkyl group. 1-5 Alkyl, particularly preferably perfluoroC 1-3 Alkyl, most preferably perfluoroC 2-3 The alkyl group is particularly preferably a perfluoroethyl group.

[0062] The above-mentioned s represents an integer of 1 to 5, preferably an integer of 2 to 4, and particularly preferably 3.

[0063] As the anion represented by the above formula (a-1), a tri(perfluoroalkyl)trifluorophosphate anion is preferred, among which a tri(perfluoroethyl)trifluorophosphate anion, a tri(perfluoropropyl)trifluorophosphate anion, and a tri(perfluorobutyl)trifluorophosphate anion are preferred, and a tri(perfluoroethyl)trifluorophosphate anion (=tris(pentafluoroethyl)trifluorophosphate anion) is particularly preferred.

[0064] As R f 12 The fluoroalkyl group in the f 11 The same example of the fluoroalkyl group.

[0065] As R f 12 The fluoroalkyl group in the present invention is preferably a perfluoroalkyl group, and particularly preferably a perfluoroalkyl group. 1-5 Alkyl, most preferably perfluoroC 1-3 alkyl.

[0066] R f 12 The fluoroaryl group in is a group in which at least one of the hydrogen atoms bonded to the aryl group is substituted with a fluorine atom. As the aryl group, for example, aryl groups having 6 to 14 carbon atoms such as phenyl and naphthyl are preferred, and phenyl is particularly preferred.

[0067] As R f 12 The fluorinated aryl group in the present invention is preferably a perfluorinated aryl group, and particularly preferably a perfluorinated C 6-14 Aryl, most preferably perfluorophenyl.

[0068] R f 12 The fluoroalkyl-substituted aryl group in the formula (a) is an aryl group having, as a substituent, at least one hydrogen atom bonded to the alkyl group substituted with a fluorine atom (ie, a fluoroalkyl group). Examples of the fluoroalkyl group and the aryl group include the same examples as those described above.

[0069] As R f 12 The fluoroalkyl substituted aryl group in the present invention is preferably a perfluoroalkyl substituted aryl group, and more preferably a perfluoroC 1-5 Alkyl substituted aryl, particularly preferably perfluoroC1-3 Alkyl substituted aryl, most preferably perfluoroC 1-3 Alkyl substituted C 6-14 Aryl, especially perfluoroC 1-3 Alkyl substituted phenyl.

[0070] In addition, R f 12 The number of the fluoroalkyl groups in the fluoroalkyl-substituted aryl group is, for example, 1 to 5, preferably 1 to 3, particularly preferably 1 or 2.

[0071] In the formula (a-2), t represents an integer of 1 to 4, preferably an integer of 2 to 4, particularly preferably 3 or 4, and most preferably 4.

[0072] In formula (a-2), u represents 0 or 1.

[0073] Examples of the anion represented by the above formula (a-2) include tetrafluorogallate anions, tetrakis(pentafluorophenyl) gallate anions; tetrakis[fluorophenyl] gallate anions such as tetrakis(4-fluorophenyl) gallate anions; tetrakis[difluorophenyl] gallate anions such as tetrakis(3,5-difluorophenyl) gallate anions; tris(pentafluorophenyl)fluorogallate anions, bis(pentafluorophenyl)difluorogallate anions, (pentafluorophenyl)trifluorogallate anions; tetrakis[4-(trifluoromethyl)phenyl] gallate anions such as tetrakis[(C 1-5 halogenated alkyl)phenyl] gallate anion; tetrakis[3,5-bis(trifluoromethyl)phenyl] gallate anion, etc. 1-5 haloalkyl)phenyl] gallate anion; tris[4-(trifluoromethyl)phenyl]fluorogallate anion, etc. 1-5 halogenated alkyl)phenyl]fluorogallate anion, etc.; tris[3,5-bis(trifluoromethyl)phenyl]fluorogallate anion, etc. 1-5 halogenated alkyl)phenyl]fluorogallate anion, etc.; bis[4-(trifluoromethyl)phenyl]difluorogallate anion, etc. 1-5 bis[(3,5-bis(trifluoromethyl)phenyl]difluorogallate anion; bis[((C 1-5 [(halogenated alkyl)phenyl]difluorodifluorogallate anion; [4-(trifluoromethyl)phenyl]trifluorogallate anion, etc. [(C 1-5 [(halogenated alkyl)phenyl]trifluorogallate anion; [3,5-bis(trifluoromethyl)phenyl]trifluorogallate anion, etc. [bis(C 1-5 [(halogenated alkyl)phenyl]trifluorogallate anion, etc.

[0074] When the acid generator includes a salt (1-1) of a cation represented by the formula (c-1) and an anion represented by the formula (a-1), solubility in the cationic curable compound tends to be further improved.

[0075] When the acid generator contains the salt (1-2) of the cation represented by the formula (c-1) and the anion represented by the formula (a-2), the cured product obtained using the acid generator tends to have improved resistance to thermal yellowing.

[0076] The acid generator may contain other salts (the so-called other salts are compounds that generate acid by thermal decomposition) in addition to the salt (1), for example, a salt (2) of a cation represented by the following formula (c-2) and an anion represented by the above formula (a-1) or (a-2).

[0077] [Chemistry 5]

[0078]

[0079] The salt (2) includes a salt (2-1) of a cation represented by the formula (c-2) and an anion represented by the formula (a-1) and a salt (2-2) of a cation represented by the formula (c-2) and an anion represented by the formula (a-2).

[0080] The acid generator may include a salt (2-1) of a cation represented by the formula (c-2) and an anion represented by the formula (a-1) in addition to the salt (1-1) of the cation represented by the formula (c-1) and the anion represented by the formula (a-1).

[0081] The acid generator may contain a salt (2-2) of a cation represented by the formula (c-2) and an anion represented by the formula (a-2) in addition to the salt (2-1) of the cation represented by the formula (c-1) and the anion represented by the formula (a-2).

[0082] In the above formula (c-2), n represents an integer of 1 or greater, for example, an integer of 1 to 3, and preferably 1 or 2.

[0083] In the above formula (c-2), R 1 , R 2 , R 3 Same as above.

[0084] When the acid generator contains both the salt (1) and the salt (2), the solubility in the cationic curable compound tends to be improved and / or the heat yellowing resistance of the obtained cured product tends to be improved.

[0085] When the acid generator contains salt (1) and salt (2), the content of salt (1) (or the proportion of salt (1) in the total of 100% by weight of salt (1) and salt (2)) is, for example, greater than 95% by weight and not more than 99.999% by weight. The content of salt (1) is preferably 96% by weight or more, more preferably 96.5% by weight or more, particularly preferably 97% by weight or more, most preferably 98% by weight or more, and particularly preferably 98.5% by weight or more, from the viewpoint of excellent decomposition efficiency and excellent curing properties. In addition, the content of salt (1) is preferably 99.99% by weight or less, more preferably 99.9% by weight or less, further preferably 99.8% by weight or less, particularly preferably 99.7% by weight or less, most preferably 99.5% by weight or less, and particularly preferably 99.3% by weight or less, from the viewpoint of further improving solubility.

[0086] When the acid generator contains the salt (1) and the salt (2), the content of the salt (2) in the total amount of the acid generator (or the proportion of the salt (2) in the total amount of the salt (1) and the salt (2) (100% by weight) is, for example, 0.001% by weight or more and 5% by weight or less. The lower limit of the content of the salt (2) is preferably 0.005% by weight, more preferably 0.01% by weight, further preferably 0.02% by weight, further preferably 0.1% by weight, further preferably 0.2% by weight, particularly preferably 0.3% by weight, most preferably 0.5% by weight, and particularly preferably 0.7% by weight, from the viewpoint of improving the solubility in the cationic curable compound and / or improving the heat yellowing resistance of the obtained cured product. The content of the salt (2) is preferably 4 wt % or less, more preferably 3.5 wt % or less, further preferably less than 3 wt %, particularly preferably 2 wt % or less, most preferably 1.5 wt % or less, and particularly preferably 1 wt % or less, from the perspective of excellent decomposition efficiency, excellent curing properties, and obtaining a cured product with excellent insulating properties.

[0087] When the acid generator contains the salt (1) and the salt (2), the content ratio of the salt (1) to the salt (2) can be calculated from the peak area ratio determined using HPLC, for example.

[0088] The acid generator may contain other salts in addition to the salt (1) and the salt (2). However, the total content of the salt (1) and the salt (2) in the total amount of the salt that generates an acid by thermal decomposition contained in the acid generator is, for example, 80% by weight or more, preferably 90% by weight or more, particularly preferably 95% by weight or more, most preferably 99% by weight or more, and particularly preferably 99.9% by weight or more. It should be noted that the upper limit of the total content is 100% by weight.

[0089] The acid generator has excellent solubility in the cationic curable compound. For example, when 2 parts by weight of the acid generator is added to a mixture of 70 parts by weight of 3',4'-epoxycyclohexylmethyl (3,4-epoxy)cyclohexanecarboxylate (trade name "Celloxide 2021P", manufactured by Daicel Corporation) and 30 parts by weight of bisphenol A diglycidyl ether (trade name "jER828", manufactured by Mitsubishi Chemical Corporation) as a cationic curable compound at 25° C. and the mixture is stirred at a stirring speed of 100 rpm using a stirring bar having a length of 2 cm, the time required for the acid generator to be completely dissolved is, for example, 5 minutes or less, preferably 3 minutes or less, and more preferably 2 minutes or less. The lower limit of the time required for the acid generator to be completely dissolved is, for example, 0.1 minutes.

[0090] Compared with the case where the acid generator contains the salt (1) alone, when the acid generator contains the salt (1) and the salt (2), the solubility in the cationic curable compound is further improved, and the time required for dissolution tends to be shortened. When the acid generator is added to the mixture of the cationic curable compound in the above ratio and stirred under the above conditions, the time required for the acid generator to be completely dissolved is, for example, less than 1 minute, preferably less than 0.5 minute.

[0091] Under completely identical conditions except for the difference in the composition of the acid generator, the time required for the acid generator to completely dissolve in the cationic curable compound tends to be shortened when the acid generator contains the salt (1) and the salt (2), compared with the case where the acid generator contains the salt (1) alone, and the shortening rate is, for example, 20% or more, preferably 30% or more, and particularly preferably 40% or more. The upper limit of the shortening rate is, for example, 80%.

[0092] The acid generator has excellent thermal sensitivity and is rapidly decomposed by heating (for example, heating at 70 to 120° C. for 30 to 120 minutes) to generate acid (H (R f 11 ) s PF 6-s or H[R f 12 (O) u ] t G JZ 4-t ). Therefore, the above-mentioned acid generator can be suitably used as a heat-sensitive acid generator.

[0093] [Method for producing acid generator]

[0094] An example of a method for producing an acid generator containing a salt (1-1) of a cation represented by the above formula (c-1) and an anion represented by the above formula (a-1) and a method for producing an acid generator containing the above salt (1-1) and a salt (2-1) of a cation represented by the above formula (c-2) and an anion represented by the above formula (a-1) are given below. It should be noted that an acid generator containing an anion represented by the above formula (a-2) instead of an anion represented by the above formula (a-1) can also be produced by the same method.

[0095] The above salt (1-1) can be prepared, for example, through the following steps I and II. In addition, the above salt (2-1) can be prepared, for example, through the following steps I, III, and IV. In the following formula, A represents a halogen atom, and M represents an alkali metal (lithium, sodium, potassium, etc.). R 1 , R 2 , R 3 , R f 11 , s, and n are the same as above.

[0096] [Chemistry 6]

[0097]

[0098] The acid generator containing the salt (1-1) can be produced, for example, through the above steps I and II. Alternatively, for example, the salt (1-1) can be produced through the above steps I and II, the salt (2-1) can be produced through the above steps I, III and IV, and the obtained salt (1-1) can be combined with the above salt (2-1) to produce the acid generator containing the salt (1-1) and the salt (2-1). In addition, the reaction of the above step I and the reaction of the step III can be carried out simultaneously to obtain a mixture of the compound represented by the above formula (3) and the compound represented by the above formula (5), and the obtained mixture can be subjected to a salt exchange reaction to produce a mixture of the salt (1-1) and the salt (2-1).

[0099] (Process I)

[0100] Step I is a step of reacting a compound represented by formula (1) (=compound (1)) with a compound represented by formula (2) (=compound (2)) to obtain a compound represented by formula (3) (=compound (3)).

[0101] The molar ratio of compound (1) to compound (2) (compound (1) / compound (2)) to be subjected to the above reaction is, for example, 1 / 3 to 3 / 1, and preferably 1 / 2 to 2 / 1.

[0102] The above reaction can be carried out in the presence of a solvent. Examples of the above solvent include acetone, acetonitrile, dimethyl sulfoxide, etc. These can be used alone or in combination of two or more.

[0103] The reaction temperature is, for example, 25 to 50°C.

[0104] (Process II)

[0105] Step II is to make M (R f 11 ) s PF 6-s A step of reacting the compound (3) obtained in step I with the compound (3) to perform salt exchange to obtain a compound represented by formula (4) (= salt (1-1)).

[0106] The compound (3) subjected to the above reaction is reacted with M (R f 11 ) s PF 6-s The molar ratio (compound (3) / M (R f 11 ) s PF 6-s ) is, for example, 1 / 3 to 3 / 1, preferably 1 / 2 to 2 / 1.

[0107] The above reaction can be carried out in the presence of a solvent. Examples of the above solvent include water, ethyl acetate, and dichloromethane. These can be used alone or in combination of two or more.

[0108] The reaction temperature is, for example, 15 to 35°C.

[0109] (Process III)

[0110] Step III is a step of reacting the compound (2) with the compound (3) obtained in step I to obtain a compound represented by formula (5).

[0111] The molar ratio of compound (3) to compound (2) (compound (3) / compound (2)) is, for example, 2 / 1 to 1 / 3, and preferably 1 / 1 to 1 / 2.

[0112] The above reaction can be carried out in the presence of a solvent. Examples of the above solvent include acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, etc. These can be used alone or in combination of two or more.

[0113] The reaction temperature is, for example, 40 to 70°C.

[0114] (Process IV)

[0115] Step IV is to make M (R f 11 ) s PF 6-sA step of reacting the compound (5) obtained in step III to perform salt exchange to obtain a compound represented by formula (6) (= salt (2-1)).

[0116] The compound (5) subjected to the above reaction is reacted with M (R f 11 ) s PF 6-s The molar ratio (compound (5) / M (R f 11 ) s PF 6-s ) is, for example, 1 / 3 to 3 / 1, preferably 1 / 2 to 2 / 1.

[0117] The above reaction can be carried out in the presence of a solvent. Examples of the above solvent include water, ethyl acetate, and dichloromethane. These can be used alone or in combination of two or more.

[0118] The reaction temperature is, for example, 15 to 35°C.

[0119] The reaction atmosphere is not particularly limited as long as it does not inhibit the reaction, and may be, for example, air atmosphere, nitrogen atmosphere, argon atmosphere, etc. The reaction may be carried out by any method such as batch method, semi-batch method, or continuous method.

[0120] After the reaction of each step is completed, the obtained reaction product can be subjected to a general separation and purification treatment (such as precipitation, washing, filtration, etc.).

[0121] [Curable composition]

[0122] The curable composition of the present invention contains the acid generator and the cationic curable compound. The acid generator and the cationic curable compound may be contained alone or in combination of two or more.

[0123] The content of the acid generator is, for example, 0.05 to 20 parts by weight, or preferably 0.1 to 10 parts by weight, relative to 100 parts by weight of the cation curable compound.

[0124] The above-mentioned cationic curable compound is a compound having one or more cationic curable groups selected from epoxy groups, oxetane groups, vinyl ether groups, etc. It should be noted that the above-mentioned epoxy group is a group containing a 3-membered cyclic ether skeleton, and the oxetane group is a group containing a 4-membered cyclic ether skeleton.

[0125] The number of cationic curable groups in one molecule of the cationic curable compound is 1 or more, and is preferably 1 to 4, more preferably 2 to 4, and particularly preferably 2 to 3, from the viewpoint of excellent solubility of the acid generator.

[0126] The molecular weight per cationically curable group of the cationically curable compound (eg cationically curable group equivalent such as epoxy equivalent and oxetane equivalent) is, for example, 50 to 500 g / eq, preferably 100 to 400 g / eq, and more preferably 100 to 300 g / eq.

[0127] Examples of the cationically curable compound include compounds having an epoxy group as a cationically curable group (=epoxy compound), compounds having an oxetane group as a cationically curable group (=oxetane compound), compounds having a vinyl ether group as a cationically curable group (=vinyl ether compound), compounds having an epoxy group and an oxetane group as a cationically curable group, compounds having an epoxy group and a vinyl ether group as a cationically curable group, compounds having an oxetane group and a vinyl ether group as a cationically curable group, and the like.

[0128] (Epoxides)

[0129] Examples of the epoxy compound include epoxy-modified siloxane compounds, alicyclic epoxy compounds (alicyclic epoxy resins), aromatic epoxy compounds (aromatic epoxy resins), and aliphatic epoxy compounds (aliphatic epoxy resins).

[0130] <Epoxy-modified silicone compounds>

[0131] Examples of the epoxy-modified siloxane compound include epoxy-modified silicone and epoxy-modified polyorganosilsesquioxane.

[0132] <Alicyclic epoxides>

[0133] Examples of the alicyclic epoxy compound include known or commonly used compounds having one or more alicyclic rings and one or more epoxy groups in the molecule, but are not particularly limited. Examples thereof include the following compounds.

[0134] (1) Compounds having an alicyclic epoxy group (= an epoxy group consisting of two adjacent carbon atoms and an oxygen atom constituting an alicyclic ring in the molecule);

[0135] (2) Compounds having an alicyclic ring and a glycidyl ether group.

[0136] Examples of the compound having an alicyclic epoxy group include 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-1-methylcyclohexyl 3,4-epoxy-1-methylhexanecarboxylate, 6-methyl-3,4-epoxycyclohexylmethyl 6-methyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-3-methylcyclohexanecarboxylate, 3,4-epoxy-3-methylcyclohexanecarboxylate, and 3,4-epoxy-1-methylcyclohexyl 6-methyl-3,4-epoxycyclohexanecarboxylate. -5-methylcyclohexanecarboxylic acid 3,4-epoxy-5-methylcyclohexylmethyl ester, 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-m-dioxane, bis(3,4-epoxycyclohexylmethyl)adipate, 3,4-epoxy-6-methylcyclohexanecarboxylate, methylenebis(3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylenebis(3,4-epoxycyclohexanecarboxylate), etc.

[0137] Examples of the compound having an alicyclic ring and a glycidyl ether group include glycidyl ethers of alicyclic alcohols (particularly alicyclic polyols). More specifically, examples include compounds obtained by hydrogenating bisphenol A type epoxy compounds such as 2,2-bis[4-(2,3-epoxypropoxy)cyclohexyl]propane and 2,2-bis[3,5-dimethyl-4-(2,3-epoxypropoxy)cyclohexyl]propane (hydrogenated bisphenol A type epoxy compounds); bis[o,o-(2,3-epoxypropoxy)cyclohexyl]methane, bis[o,p-(2,3-epoxypropoxy)cyclohexyl]methane, bis[p,p-(2,3-epoxypropoxy)cyclohexyl]methane, Compounds obtained by hydrogenating bisphenol F type epoxy compounds such as [3,5-dimethyl-4-(2,3-epoxypropoxy)cyclohexyl]methane, bis[3,5-dimethyl-4-(2,3-epoxypropoxy)cyclohexyl]methane (hydrogenated bisphenol F type epoxy compounds); hydrogenated biphenol type epoxy compounds; hydrogenated phenol novolac type epoxy compounds; hydrogenated cresol novolac type epoxy compounds; hydrogenated cresol novolac type epoxy compounds of bisphenol A; hydrogenated naphthalene type epoxy compounds; hydrogenated products of trisphenol methane type epoxy compounds, etc.

[0138] <Aromatic Epoxides>

[0139] Examples of the aromatic epoxy compounds include Epi-bis glycidyl ether epoxy resins obtained by condensation reaction of bisphenols [e.g., bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, etc.] with epihalohydrin; high molecular weight Epi-bis glycidyl ether epoxy resins obtained by further addition reaction of these Epi-bis glycidyl ether epoxy resins with the above bisphenols; and high molecular weight Epi-bis glycidyl ether epoxy resins obtained by addition reaction of phenols [e.g., phenol, cresol, xylenol, isophthalic acid, etc.]. A linear phenol-alkyl glycidyl ether type epoxy resin obtained by a condensation reaction of phenol, catechol, bisphenol A, bisphenol F, bisphenol S, etc.] with an aldehyde [such as formaldehyde, acetaldehyde, benzaldehyde, hydroxybenzaldehyde, salicylaldehyde, etc.], and further a condensation reaction of the obtained polyols with an epihalohydrin; an epoxy compound in which two phenol skeletons are bonded to the 9-position of the fluorene ring, and a glycidyl group is bonded to the oxygen atoms obtained by removing hydrogen atoms from the hydroxyl groups of these phenol skeletons directly or via an alkylene oxide group.

[0140] <Aliphatic Epoxides>

[0141] Examples of the aliphatic epoxy compounds include glycidyl ethers of q-valent alcohols (q is a natural number) not having a ring structure; glycidyl esters of monovalent or polyvalent carboxylic acids [such as acetic acid, propionic acid, butyric acid, stearic acid, adipic acid, sebacic acid, maleic acid, itaconic acid, etc.]; epoxides of fats and oils having double bonds such as epoxidized linseed oil, epoxidized soybean oil, and epoxidized castor oil; and epoxides of polyolefins (including polyalkadiene) such as epoxidized polybutadiene. It should be noted that, as the above-mentioned q-valent alcohol without a ring structure, for example, monohydric alcohols such as methanol, ethanol, 1-propanol, isopropanol, and 1-butanol can be cited; dihydric alcohols such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, neopentyl glycol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol, and polypropylene glycol; trihydric or higher polyhydric alcohols such as glycerol, diglycerol, erythritol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, and sorbitol, etc. In addition, the q-valent alcohol can also be a polyether polyol, a polyester polyol, a polycarbonate polyol, a polyolefin polyol, etc.

[0142] (Oxetane compounds)

[0143] Examples of the oxetane compound include 3,3-bis(vinyloxymethyl)oxetane, 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, 3-ethyl-3-(hydroxymethyl)oxetane, 3-ethyl-3-[(phenoxy)methyl]oxetane, 3-ethyl-3-(hexyloxymethyl)oxetane, 3-ethyl-3-(chloromethyl)oxetane, 3,3-bis(chloromethyl)oxetane, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl] Benzene, bis([1-ethyl(3-oxetanyl)]methyl)ether, 4,4'-bis[(3-ethyl-3-oxetanyl)methoxymethyl]bicyclohexane, 4,4'-bis[3-ethyl-(3-oxetanyl)methoxymethyl]biphenyl, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]cyclohexane, 1,4-bis([(3-ethyl-3-oxetanyl)methoxy]methyl)benzene, 3-ethyl-3([(3-ethyloxetan-3-yl)methoxy]methyl)oxetane, xylylenebisoxetane, etc.

[0144] (Vinyl ether compounds)

[0145] Examples of the vinyl ether compound include aryl vinyl ethers such as phenyl vinyl ether; alkyl vinyl ethers such as n-butyl vinyl ether and n-octyl vinyl ether; cycloalkyl vinyl ethers such as cyclohexyl vinyl ether; vinyl ethers having a hydroxyl group such as 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether and 2-hydroxybutyl vinyl ether; polyfunctional vinyl ethers such as hydroquinone divinyl ether, 1,4-butanediol divinyl ether, cyclohexane divinyl ether, cyclohexanedimethanol divinyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether and triethylene glycol divinyl ether; and the like.

[0146] The cationic curable compound preferably contains at least an alicyclic epoxy compound having one or more (preferably 1 to 4) alicyclic epoxy groups (particularly a polyfunctional alicyclic epoxy compound having two or more (preferably 2 to 4) alicyclic epoxy groups).

[0147] The above-mentioned cationic curable compound may be used in combination with the above-mentioned alicyclic epoxy compound and a glycidyl ether type epoxy compound having one or more (preferably 1 to 4) glycidyl ether groups and / or an oxetane compound having one or more (preferably 1 to 4) oxetane groups. When used in combination, the mixing ratio [alicyclic epoxy compound / (glycidyl ether type epoxy compound and oxetane compound); weight ratio] is, for example, 95 / 5 to 5 / 95, preferably 95 / 5 to 30 / 70, more preferably 95 / 5 to 40 / 60, further preferably 95 / 5 to 60 / 40, particularly preferably 90 / 10 to 65 / 35, and most preferably 85 / 15 to 65 / 35.

[0148] The curable composition may contain one or more other components as required in addition to the above components. As other components, for example, sensitizers, sensitizing aids, antioxidants, stabilizers, surfactants, solvents, rheology control agents, leveling agents, silane coupling agents, fillers, conductive particles, polymerization inhibitors, light stabilizers, plasticizers, defoamers, foaming agents, ultraviolet absorbers, tackifiers, curing retarders, ion adsorbents, pigments, dyes, fluorescent substances, mold release agents, antistatic agents, flame retardants, free radical curable compounds, polyimide resins, polyamide resins, phenoxy resins, poly (methyl) acrylate resins, polyurethane resins, polyurea resins, polyester resins, polyvinyl butyral resins, SBS, SEBS, etc. Their content (the total amount when containing more than two kinds) is, for example, less than 50% by weight of the total amount (100% by weight) of the curable composition, preferably less than 10% by weight, and particularly preferably less than 5% by weight. The content of these is, for example, 0.05% by weight or more, and preferably 0.1% by weight or more, based on the total amount (100% by weight) of the curable composition.

[0149] The curable composition can be prepared by uniformly mixing the acid generator, the cationic curable compound and other components added as needed using a generally known mixing device such as a rotation-revolution stirring degassing device, a homogenizer, a planetary mixer, a three-roll mill, a bead mill, etc. It should be noted that the components can be mixed simultaneously or sequentially.

[0150] The acid generator contained in the curable composition has excellent solubility in the cationic curable compound and can be reliably dissolved by a short dissolution operation. In addition, precipitation over time can be suppressed. Therefore, the curable composition can be efficiently prepared, there is ample time from preparation to use, and the operability is also excellent.

[0151] The curable composition contains the acid generator in a completely dissolved state, so it has excellent curability. In addition, the cured product of the curable composition has excellent electrical insulation and does not have charging properties caused by the insoluble components of the acid generator. In addition, the cured product has excellent resistance to heat yellowing and can stably maintain transparency even when exposed to high temperature environments.

[0152] The use of the above-mentioned curable composition is not particularly limited, and examples thereof include coatings, coating agents, inks, positive resists, resist films, liquid resists, photosensitive materials, adhesives, molding materials, injection molding materials, putties, glass fiber impregnation agents, gap filling materials, sealing materials, sealants, photomolding materials, etc.

[0153] The curable composition can form a cured product with excellent heat-resistant yellowing properties as described above, and therefore can be suitably used as a raw material for optical materials. It should be noted that the optical materials include lenses such as eyeglass lenses, (digital) camera lenses, beam focusing lenses, and light diffusion lenses; LED sealing materials, optical adhesives, light transmission bonding materials, prisms, filters, diffraction gratings, and protective glasses for display devices.

[0154] [Cured product]

[0155] The cured product of the present invention is a cured product of the above-mentioned curable composition.

[0156] The above-mentioned cured product can be obtained by curing the above-mentioned curable composition.

[0157] The curable composition can be cured by heat treatment at a temperature of, for example, 70 to 120° C. for a heating time of, for example, 0.5 to 2 hours.

[0158] Since the solidified material does not contain any insoluble components of the acid generator or the amount of the insoluble components of the acid generator remaining is extremely low, the conductivity of the extracted water obtained by extracting the ion components contained in the solidified material with water (more specifically, the extracted water obtained by the method described in the Examples) is, for example, less than 50 μS / cm, preferably 40 μS / cm or less, particularly preferably 30 μS / cm or less, and most preferably less than 25 μS / cm.

[0159] As described above, the cured product has low electrical conductivity and excellent insulation properties. Therefore, if the cured product is used for sealing purposes, a semiconductor element having excellent short-circuit resistance and high reliability can be obtained.

[0160] In addition, when the acid generator is unevenly distributed in the above-mentioned cured product, when exposed to a high temperature environment, the acid generator decomposes and unevenly generates acid, causing the cured product to turn yellow. However, since the above-mentioned cured product uniformly contains the acid generator or the uneven distribution of the acid generator is suppressed, yellowing caused by the acid can be suppressed even when exposed to a high temperature environment, and the color tone of the cured product can be stably maintained.

[0161] The yellowing of the cured product due to high temperature exposure is suppressed, and the increase rate of the yellowness index (YI) calculated according to the following formula is, for example, 130% or less, preferably 120% or less, more preferably 110% or less, further preferably 90% or less, further preferably 80% or less, further preferably 70% or less, particularly preferably 50% or less, most preferably 25% or less, and particularly preferably 10% or less. It should be noted that the lower limit of the increase rate of the yellowness index (YI) is 0%.

[0162] Yellowness increase rate (%) = [(YIa-YIb) / YIb] × 100

[0163] (In the above formula, YIb represents the yellowness of the cured product before high temperature exposure, and YIa represents the yellowness of the cured product after high temperature exposure. It should be noted that the above high temperature exposure was performed by continuously performing a heat resistance test based on the reflow temperature profile described in the JEDEC standard (maximum temperature: 270°C) three times)

[0164] The yellowness index (YI) of the cured product after high temperature exposure is, for example, 3.0 or less, preferably 2.5 or less, particularly preferably 2.0 or less, most preferably 1.2 or less, and particularly preferably 1.0 or less. The lower limit of the yellowness index (YI) is, for example, 0.

[0165] The above-mentioned configurations and combinations thereof of the present invention are merely examples, and additions, omissions, substitutions, and changes to the configurations may be appropriately made without departing from the spirit of the present invention.

[0166] Example

[0167] Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.

[0168] Example 1

[0169] [Preparation of Salt (1-1a)]

[0170] (Process I)

[0171] 50.0 g of N,N-dimethylaniline, 64.6 g of 4-methoxybenzyl chloride, and 16.9 g of acetonitrile were mixed and heated to 50° C. The temperature of the reaction solution (50° C.) was maintained for 5 hours to complete the reaction.

[0172] 250 g of acetone was added to the reaction solution, and the temperature was lowered to below 10° C. and stirred for 1 hour. Thereafter, the reaction solution was filtered and the generated solid was separated and collected to obtain 81.3 g of N-(4-methoxybenzyl)-N,N-dimethylanilinium chloride.

[0173] (Process II)

[0174] 50.0 g of N-(4-methoxybenzyl)-N,N-dimethylanilinium chloride obtained in step I was dissolved in 200 g of ion-exchanged water, and 250 g of dichloromethane and 26.4 g of tris(perfluoroethyl) potassium trifluorophosphate were added in this order.

[0175] After the addition was completed, the reaction was stirred at room temperature for 1 hour to complete the reaction, the aqueous layer was removed, and the organic layer was washed three times with 300 g of ion exchange water. Thereafter, the organic layer was desolvated to obtain a cation represented by the following formula (c-1-1) and a tri(perfluoroethyl)trifluorophosphate anion ((CF3CF2)3PF3 - ) 113 g of salt (1-1a). 1 H-NMR shows Figure 1 In 19 The results of F-NMR measurements are shown in Figure 2 middle.

[0176] The obtained salt (1-1a) is referred to as acid generator 1.

[0177] [Chemistry 7]

[0178]

[0179] Example 2

[0180] [Preparation of Salt (1-1a)]

[0181] The same method as in Example 1 was used to obtain the cation represented by the above formula (c-1-1) and the tri(perfluoroethyl)trifluorophosphate anion ((CF3CF2)3PF3 - ) of a salt (1-1a).

[0182] [Preparation of Salt (2-1a)]

[0183] (Process I)

[0184] The same procedure as in step I of Example 1 was carried out to obtain N-(4-methoxybenzyl)-N,N-dimethylanilinium chloride.

[0185] (Process III)

[0186] 10 g of the obtained N-(4-methoxybenzyl)-N,N-dimethylanilinium chloride was dissolved in 5.31 g of acetonitrile, and 8.45 g of 4-methoxybenzyl chloride was added.

[0187] After the addition was completed, the temperature was raised to 70°C and stirred for 5 hours to complete the reaction.

[0188] To the reaction solution were added 30 g of ion-exchanged water and 50 g of ethyl acetate, followed by stirring at room temperature for 30 minutes, and then the aqueous layer was removed. The organic layer was washed three times with 30 g of ion-exchanged water to remove the solvent.

[0189] After the solvent was removed, 5.0 g of methanol was added to the obtained yellow oily residue to dissolve the residue and obtain a methanol solution. The obtained methanol solution was slowly poured into 30.0 g of methyl-tert-butyl ether under stirring to precipitate crystals.

[0190] The precipitated crystals were separated and collected by filtration, and dried under reduced pressure to obtain 9.48 g of a chloride salt of a cation represented by the following formula (c-2-1) (where n1=1).

[0191] [Chemistry 8]

[0192]

[0193] (Process IV)

[0194] The obtained chloride salt 7.95g was subjected to salt exchange with 9.65g of potassium tri(perfluoroethyl) trifluorophosphate by the same method as step II of Example 1 to obtain a cation represented by the above formula (c-2-1) (where n1=1) and a tri(perfluoroethyl) trifluorophosphate anion ((CF3CF2)3PF3 - ) salt (2-1a) 13.8g.

[0195] [Preparation of acid generator]

[0196] 99.98 g of the obtained salt (1-1a) and 0.02 g of the salt (2-1a) were mixed to obtain an acid generator 2 in which the content of the salt (2-1a) was 0.02% by weight of the total amount of the mixture.

[0197] Example 3

[0198] Acid Generator 3 was obtained in the same manner as in Example 2 except that the content of Salt (2-1a) was changed to 0.1% by weight in the step [Preparation of Acid Generator].

[0199] Example 4

[0200] Acid Generator 4 was obtained in the same manner as in Example 2 except that the content of Salt (2-1a) was changed to 0.5% by weight in the step [Preparation of Acid Generator].

[0201] Example 5

[0202] Acid Generator 5 was obtained in the same manner as in Example 2 except that the content of Salt (2-1a) was changed to 1% by weight in the step [Preparation of Acid Generator].

[0203] Example 6

[0204] Acid Generator 6 was obtained in the same manner as in Example 2 except that the content of Salt (2-1a) was changed to 3% by weight in the step [Preparation of Acid Generator].

[0205] Example 7

[0206] Acid Generator 7 was obtained in the same manner as in Example 2 except that the content of Salt (2-1a) was changed to 5% by weight in the step of [Preparation of Acid Generator].

[0207] Comparative Example 1

[0208] The cation represented by the above formula (c-1-1) and B(C6F5)4 - The salt of is set as the acid generator 10.

[0209] Comparative Example 2

[0210] The cation represented by the above formula (c-1-1) and SbF6 are obtained. - A salt of is set as acid generator 11.

[0211] Comparative Example 3

[0212] The cation shown in the above formula (c-1-1) and PF6 - is used as the acid generator 12.

[0213] Examples 8 to 20, Comparative Examples 4 to 6

[0214] (Preparation of Curable Composition)

[0215] Each component according to the formulation described in the following table (unit: parts by weight) was added to a beaker, and a stirring bar was added thereto. A dissolution treatment was performed by stirring at 20° C. and 100 rpm to obtain a curable composition.

[0216] Embodiment 21

[0217] [Preparation of Salt (1-2a)]

[0218] The cation represented by the above formula (c-1-1) and the tetrakis(pentafluorophenyl) gallate anion (Ga(C6F5)4) were obtained in the same manner as in Example 1 except that sodium tetrakis(pentafluorophenyl) gallate was used instead of potassium tris(perfluoroethyl) trifluorophosphate. -) of the salt (1-2a). 1 H-NMR shows Figure 3 In 19 The results of F-NMR measurements are shown in Figure 4 middle.

[0219] The obtained salt (1-2a) is used as the acid generator 8.

[0220] Embodiment 22

[0221] [Preparation of Salt (1-2a)]

[0222] By the same method as in Example 21, the cation represented by the above formula (c-1-1) and the tetrakis(pentafluorophenyl) gallate anion (Ga(C6F5)4 - ) of a salt (1-2a).

[0223] [Preparation of Salt (2-2a)]

[0224] The cation represented by the above formula (c-2-1) (where n1=1) and the tetrakis(pentafluorophenyl) gallate anion (Ga(C6F5)4) were prepared in the same manner as in the salt (2-1a) of Example 2 except that sodium tetrakis(pentafluorophenyl) gallate was used instead of potassium tris(perfluoroethyl) trifluorophosphate. - ) of salt (2-2a).

[0225] [Preparation of acid generator]

[0226] 99.98 g of the obtained Salt (1-2a) and 0.02 g of the Salt (2-2a) were mixed to obtain an acid generator 9 in which the content of the Salt (2-2a) was 0.02% by weight based on the total amount of the mixture.

[0227] Embodiments 23 to 25

[0228] (Preparation of Curable Composition)

[0229] Each component according to the formulation described in the following table (unit: parts by weight) was added to a beaker, and a stirring bar was added to carry out a dissolution treatment by stirring at 20° C. and 100 rpm to obtain a curable composition.

[0230] (Solubility evaluation)

[0231] In Examples 8 to 20, 23 to 25 and Comparative Examples 4 to 6, the dissolution treatment time required until the acid generator was completely dissolved was measured, and the solubility was evaluated according to the following criteria.

[0232] <Evaluation Criteria>

[0233] ◎ (Excellent): Dissolution time is less than 1 minute

[0234] ○ (good): Dissolution treatment time is 1 minute or more and 5 minutes or less

[0235] × (Unqualified): Dissolution time is greater than 5 minutes

[0236] Reference Examples 1 and 2

[0237] Each component according to the formulation described in the following table (unit: parts by weight) was added to a beaker, and a stirring bar was added thereto, and the mixture was stirred at 20° C. and 100 rpm for 0.5 minutes to obtain a curable composition.

[0238] In the obtained curable composition, an insoluble component remains.

[0239] (Evaluation of curing properties)

[0240] The curable compositions obtained in Examples, Comparative Examples and Reference Examples were applied to a polyphenylene ether substrate using a bar coater to a thickness of 50 μm, and then heated in a hot air dryer at 100° C. for 1 hour to obtain a cured product.

[0241] The surface of the obtained cured product was rubbed back and forth 10 times with a cotton swab soaked in acetone at a load of 300 g or 500 g, and the rubbed surface was visually observed to evaluate the curability according to the following criteria.

[0242] <Evaluation Criteria>

[0243] ◎ (Excellent): No change in appearance when rubbed with a load of 500g

[0244] ○ (Good): Scratches were observed when rubbed with a load of 500 g, but no changes in appearance were observed when rubbed with a load of 300 g

[0245] △ (Pass): When rubbed with a load of 300 g, no loss of gloss or dissolution of the film was observed, but scratches were observed

[0246] × (failed): When rubbed with a load of 300 g, loss of gloss or dissolution of the film was observed.

[0247] (Insulation evaluation)

[0248] The curable compositions obtained in Examples, Comparative Examples and Reference Examples were prepared by the same method as in the above (Evaluation of Curability). The obtained cured products were peeled from the polyphenylene ether substrate and accurately weighed to obtain test pieces of about 0.2 g.

[0249] The thus obtained test piece and 10 g of ion-exchanged distilled water were placed in a Teflon (registered trademark) PCT container, which was placed in a SUS pressure container and sealed, and allowed to stand at 141° C. and 2 atmospheres for 20 hours, and then naturally cooled to room temperature.

[0250] Thereafter, the water in the PCT container was taken out and the electrical conductivity was measured, and the insulation properties were evaluated according to the following criteria.

[0251] <Evaluation Criteria>

[0252] ◎ (Excellent): Conductivity less than 25μS / cm

[0253] ○ (good): conductivity is 25 μS / cm or more and less than 50 μS / cm

[0254] △ (qualified): conductivity is 50μS / cm or more and less than 100μS / cm

[0255] × (unqualified): conductivity is 100μS / cm or more

[0256] (Evaluation of thermal yellowing resistance)

[0257] A spacer of 20 mm in length × 20 mm in width × 0.1 mm in thickness was prepared and sandwiched between slide glasses.

[0258] The spacer was filled with the curable composition obtained in the examples, comparative examples and reference examples, and then heated at 130° C. for 1 hour using a hot air dryer to cure the curable composition to obtain a cured product. The yellowness (YIb) of the cured product was measured.

[0259] Afterwards, the obtained cured product was subjected to a heat resistance test based on the reflow temperature curve (maximum temperature: 270°C) described in the JEDEC standard for three consecutive times, and the yellowness (YIa) of the cured product after the heat resistance test was measured. It should be noted that YIb and YIa were measured using a spectrophotometer using a D65 light source. Thereafter, the increase rate (%) of YI was calculated according to the following formula.

[0260] YI increase rate (%) = [(YIa-YIb) / YIb] × 100

[0261] [Table 1]

[0262]

[0263] [Table 2]

[0264]

[0265] <Cationic curable compound>

[0266] 2021P: 3',4'-epoxycyclohexylmethyl (3,4-epoxy)cyclohexanecarboxylate, epoxy equivalent 127 g / eq, number of epoxy groups in one molecule 2, trade name "Celloxide 2021P", manufactured by Daicel Co., Ltd.

[0267] jER828: Bisphenol A diglycidyl ether, epoxy equivalent 189 g / eq, number of epoxy groups in one molecule is 2, manufactured by Mitsubishi Chemical Corporation

[0268] jERYX8000: Hydrogenated bisphenol A diglycidyl ether, epoxy equivalent 205 g / eq, manufactured by Mitsubishi Chemical Corporation

[0269] VG3101L: Epoxy compound represented by the following formula, epoxy equivalent 209 g / eq, number of epoxy groups in one molecule 3, trade name "TECHMORE VG3101L", manufactured by PRINTEC Co., Ltd.

[0270] [Chemistry 9]

[0271]

[0272] OXT-121: 1,4-bis[(3-ethyloxetane-3-yl)methoxymethyl]benzene, oxetane equivalent 167 g / eq, number of oxetane groups in one molecule is 2, manufactured by Toagosei Co., Ltd.

[0273] OXT-221: 3,3'-(oxybismethylene)bis(3-ethyloxetane), manufactured by Toa Gosei Co., Ltd.

[0274] EX-146: p-tert-butylphenyl glycidyl ether, oxetane equivalent 107 g / eq, number of oxetane groups in one molecule 2, trade name "DENACOL EX-146", manufactured by Nagase ChemteX Co., Ltd.

[0275] <Silane coupling agent>

[0276] KBM-403: 3-Glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.

[0277] <Defoaming agent>

[0278] BYK1790: Made by BYK Chemie Japan Co., Ltd.

[0279] <Leveling agent>

[0280] LS-460: Ether modified silicone, manufactured by Kusumoto Chemical Co., Ltd.

[0281] Industrial Applicability

[0282] The acid generator of the present invention has excellent solubility in a cationic curable compound.

[0283] Therefore, by mixing the acid generator and the cationic curable compound and stirring them for a short time, the acid generator can be completely dissolved, and the curable composition can be efficiently produced.

[0284] The curable composition obtained by the above method has excellent storage stability and can suppress the precipitation of the acid generator over time. In addition, the curable composition can be quickly formed into a cured product by heat treatment.

[0285] Furthermore, the cured product of the curable composition has excellent insulation properties and excellent resistance to thermal yellowing. Therefore, the cured product can maintain transparency for a long time even in a high temperature environment.

Claims

1. An acid generator comprising a salt (1) of a cation represented by the following formula (c-1) and an anion represented by the following formula (a-1) or (a-2): In formula (c-1), R 1 , R 2 , R 3 are the same or different and represent an alkyl group having 1 to 6 carbon atoms; in formula (a-1), R f 11 represents a fluoroalkyl group, s represents an integer of 1 to 5; in formula (a-2), R f 12 represents a fluoroalkyl group, a fluoroaryl group, or a fluoroalkyl-substituted aryl group, t represents an integer of 1 to 4, and u represents 0 or 1.

2. The acid generator according to claim 1, further comprising a salt (2) of a cation represented by the following formula (c-2) and the anion, wherein the content of the salt (2) is 0.001 wt % or more and 5 wt % or less: In formula (c-2), n represents an integer greater than 1; R 1 , R 2 , R 3 Same as above. 3 . A curable composition comprising the acid generator according to claim 1 or 2 and a cationic curable compound. 4 . A cured product, which is a cured product of the curable composition according to claim 3 .

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