TW202122444A - Cationically curable composition, cured product, and joined body - Google Patents

Abstract

The purpose of the present invention is to provide a cationically curable composition that exhibits an excellent adhesiveness with aluminum die castings, PPS, and the like, while retaining photocurability and low-temperature curability. The present invention is a cationically curable composition that contains components (A) to (E) and contains 12-100 parts by mass of component (E) per a total of 100 parts by mass of component (A) and component (B). Component (A) is an aromatic epoxy resin, component (B) is at least one among a hydrogenated epoxy resin (B1) and an alicyclic epoxy resin (B2), component (C) is a photo-cationic polymerization initiator, component (D) is a thermal cationic polymerization initiator, and component (E) is a polycaprolactone polyol that has at least three hydroxyl groups and a molecular weight of not more than 1,700.

Description

Cationic curable composition, hardened product and bonded body

The present invention relates to a cationic curable composition, a cured product, and a joined body.

Traditionally, cationic curable compositions containing epoxy resins have excellent adhesion, sealing properties, high strength, heat resistance, electrical properties, and chemical resistance. Therefore, they have been used in adhesives, sealants, potting agents, and coatings. Various applications such as chemicals, conductive adhesives, etc. Moreover, it has a wide range of goals, especially in electronic/electrical equipment, for flat panel displays such as liquid crystal displays, organic electroluminescence, touch panels, hard disk devices, mobile terminal devices, semiconductors, and camera modules.

Japanese Patent Laid-Open No. 59-204676 discloses a photocationically polymerizable resin composition containing an epoxy resin and a photocationic polymerization initiator that generates Lewis acid upon irradiation with active energy rays such as ultraviolet rays. Furthermore, International Publication No. 2005/059002 (corresponding to the specification of U.S. Patent Application Publication No. 2007/0208106) discloses a cationic curing epoxy resin composition containing an epoxy resin component and a photocationic polymerization initiator , Thermal cationic polymerization initiator and filler.

However, the cationically polymerizable resin composition disclosed in Japanese Patent Application Laid-Open No. 59-204676 has the problem that it cannot harden a place that is not exposed to light. In order to solve this problem, when heated to about 200°C, acid can be generated from the cationic initiator and hardened. However, due to the high temperature hardening condition, it is difficult to apply to liquid crystal display elements and liquid crystal display elements that are prone to deterioration due to heat. Problems with applications such as organic EL elements. On the other hand, the cationic-curing epoxy resin composition disclosed in International Publication No. 2005/059002 (corresponding to the specification of U.S. Patent Application Publication No. 2007/0208106), for places that are not exposed to light, even though it has been The polymerization initiator is improved so that it can be hardened at a relatively low temperature. However, it is compatible with electronic/electric parts modules, aluminum die-casting materials commonly used as automotive parts, polyphenylene sulfide (PPS), etc. Its adhesion is poor.

The object of the present invention is to solve the above-mentioned problems, that is, to provide a cationic curable composition having excellent adhesiveness to aluminum die-cast products, PPS, etc., while maintaining photocuring properties and low-temperature curability.

The present invention overcomes the above-mentioned historical problems. That is, the present invention has the following points.

[1] A cationic curable composition comprising the following components (A) to (E), and containing 12-100 parts by mass relative to 100 parts by mass of the total amount of (A) component and (B) component ( E) Ingredients, (A)Component: Aromatic epoxy resin (B) Component: at least one of hydrogenated epoxy resin (B1) and alicyclic epoxy resin (B2) (C)Component: photocationic polymerization initiator (D)Component: Thermal cationic polymerization initiator (E) Component: a polycaprolactone polyol having trifunctional or higher (including trifunctional) hydroxyl groups and a molecular weight of 1700 or lower (including 1700).

[2] The cationic curable composition according to the above [1], wherein the content of the component (B) is 10 to 80 parts by mass relative to 100 parts by mass of the total amount of the component (A) and the component (B).

[3] The cationic curable composition according to the above [1] or [2], wherein the component (D) is selected from the group consisting of an aromatic sulfonium-based thermal cationic polymerization initiator and an aromatic iodonium-based thermal cationic polymerization initiator, And at least one of the group of thermal cationic polymerization initiators containing amine salts.

[4] The cationic curable composition according to any one of the above [1] to [3], wherein the component (D) is a thermal cationic polymerization initiator containing a salt of a quaternary ammonium cation.

[5] The cationic curable composition according to any one of [1] to [4] above, wherein the component (C) contains at least one of an aromatic iodonium salt and an aromatic sulphur salt.

[6] The cationic curable composition according to any one of the above [1] to [5], wherein the component (A) is selected from the group consisting of aromatic bisphenol A type epoxy resins and aromatic bisphenol F type rings Oxygen resin, and at least one of the group consisting of aromatic bisphenol E epoxy resin.

[7] The cationic curable composition according to any one of the above [1] to [6], wherein the component (B) only contains the hydrogenated epoxy resin (B1) and the alicyclic epoxy resin (B2) Any of them.

[8] The cationic curable composition according to any one of [1] to [6], wherein the component (B) contains a hydrogenated epoxy resin (B1) and an alicyclic epoxy resin (B2).

[9] The cationic curable composition according to any one of [1] to [8] above, which is used as an adhesive.

[10] The cationic curable composition according to any one of [1] to [8] above, which is used as an adhesive when the adherend is an aluminum die-cast product or PPS.

[11] A cured product, which is a cured product of the cationic curable composition according to any one of [1] to [10].

[12] A joined body obtained by using the cationic curable composition of any one of [1] to [10] and adhering to the adherend.

Hereinafter, the present invention will be described in detail. In addition, in this specification, "X～Y" are used to indicate the numerical values (X and Y) described before and after it as the lower limit and upper limit, and mean "X or more (including X) and less than Y (including Y). )".

＜Cationic curable composition＞ The components (A) to (B) contained in the cationic curable composition of the present invention are as follows.

(A)Component: Aromatic epoxy resin (B) Component: at least one of hydrogenated epoxy resin (B1) and alicyclic epoxy resin (B2) (C)Component: photocationic polymerization initiator (D)Component: Thermal cationic polymerization initiator (E) Component: a polycaprolactone polyol having trifunctional or higher (including trifunctional) hydroxyl groups and a molecular weight of 1500 or less (including 1500).

＜(A) Ingredient＞ The aromatic epoxy resin of the component (A) in the present invention refers to a compound that initiates a crosslinking reaction with a cationic species generated from a cationic polymerization initiator by irradiation or heating of active energy rays. (A) The type of component is not particularly limited. Examples include aromatic bisphenol A epoxy resin, aromatic bisphenol F epoxy resin, aromatic bisphenol E epoxy resin, and aromatic bisphenol Diglycidyl ether of type A alkylene oxide adduct, diglycidyl ether of aromatic bisphenol F type alkylene oxide adduct, and aromatic bisphenol E type alkylene oxide addition Diglycidyl ether, aromatic novolac type epoxy resin, urethane modified aromatic epoxy resin, nitrogen-containing aromatic epoxy resin, containing polybutadiene or nitrile butadiene rubber ( NBR) and other rubber modified aromatic epoxy resins. Among these, from the viewpoint of obtaining a cationic curable composition having excellent adhesion to aluminum die-cast products, PPS, etc., aromatic bisphenol A type epoxy resins, aromatic bisphenol F type epoxy resins, or Aromatic bisphenol E type epoxy resin is preferred.

Examples of commercially available aromatic epoxy resins include: jER (registered trademark, the same hereinafter) 825, jER827, jER828, jER828EL, jER828US, jER828XA, jER834, jER806, jER806H, jER807, jER807ST, jER604, jER630 (above manufactured by Mitsubishi Chemical Corporation); EPICLON (registered trademark, the same below) 830, EPICLON EXA-830LVP, EPICLON EXA-850CRP, EPICLON 835LV, EPICLON HP4032D, EPICLON 703, EPICLON 720, EPICLON 726, EPICLON HP820, EPICLON N-660, EPICLON N-680, EPICLON -695, EPICLON N-655-EXP-S, EPICLON N-665-EXP-S, EPICLON N-685-EXP-S, EPICLON N-740, EPICLON N-775 , EPICLON N-865 (manufactured by DIC Co., Ltd. above); ADEKA RESIN (registered trademark, the same below) EP4100, ADEKA RESIN EP4000, ADEKA RESIN EP4080, ADEKA RESIN EP4085, ADEKA RESIN EP4088, ADEKA RESIN EP4100HF, ADEKA RESIN EP4901HF, ADEKA RESIN EP4000S, ADEKA RESIN EP4000L, ADEKA RESIN EP4003S, ADEKA RESIN EP4010S, ADEKA RESIN EP4010L (the above are manufactured by ADEKA Co., Ltd.); DENACOL (registered trademark, the same below) EX-614B, DENACOL EX-411, DENACOL EX-314 , DENACOL EX-201, DENACOL EX-212, DENACOL EX-252 (manufactured by Nagase ChemteX Co., Ltd.), etc., but not limited to these. These aromatic epoxy resins may be used alone, or two or more types (including two types) may be mixed and used.

＜(B) Ingredient＞ The (B) component of the present invention is at least one of the hydrogenated epoxy resin (B1) and the alicyclic epoxy resin (B2), and the cations generated by the cationic polymerization initiator are irradiated or heated by active energy rays. Kind of compound that initiates the cross-linking reaction. The hydrogenated epoxy resin (B1) and the alicyclic epoxy resin (B2) may be used individually, or the hydrogenated epoxy resin (B1) and the alicyclic epoxy resin (B2) may be used in combination. When the hydrogenated epoxy resin (B1) and the alicyclic epoxy resin (B2) are used alone, they are preferred because they have better adhesion to aluminum die-cast products. In addition, when these are used in combination, they have an excellent balance between photocurability and low-temperature curability, and can maintain proper adhesion to various members, which is preferable. In addition, the hydrogenated epoxy resin (B1) refers to a compound having no unsaturated bond obtained by nuclear hydrogenation of the aromatic ring of an aromatic epoxy resin.

The type of hydrogenated epoxy resin (B1) is not particularly limited, and examples include hydrogenated bisphenol A epoxy resin, hydrogenated bisphenol F epoxy resin, hydrogenated bisphenol E epoxy resin, and hydrogenated bisphenol A epoxy resin. Diglycidyl ether of alkylene oxide adduct, hydrogenated bisphenol F type diglycidyl ether of alkylene oxide adduct, hydrogenated phenol novolac epoxy resin, hydrogenated cresol novolac epoxy Resin etc. Among them, from the viewpoint of obtaining a cationic curable composition having excellent adhesion with aluminum die-cast products, PPS, etc., hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, or hydrogenated Bisphenol E type epoxy resin is preferred.

Commercially available hydrogenated bisphenol A epoxy resins include, for example: jER YX-8000, jER YX-8034 (manufactured by Mitsubishi Chemical Co., Ltd. above); EPICLON EXA-7015 (manufactured by DIC Co., Ltd.) ; ST-3000 (manufactured by Nippon Steel Chemical Materials Co., Ltd.); RIKA RESIN HBE-100 (manufactured by Nippon Rika Co., Ltd.); DENACOL EX-252 (manufactured by Nagase ChemteX Co., Ltd.), etc. Moreover, as for the commercially available product of the hydrogenated bisphenol F type epoxy resin, for example, YL-6753 (manufactured by Mitsubishi Chemical Co., Ltd.) and the like can be mentioned.

Examples of the alicyclic epoxy resin (B2) are compounds having a functional group represented by the following formula (1). More specific examples are not particularly limited, and examples include 3,4-epoxycyclohexylmethyl (3',4'-epoxy)cyclohexane carboxylate, ε-caprolactone modification 3 ',4'-epoxycyclohexyl methyl, 3,4-epoxycyclohexane carboxylate, bis(3,4-epoxycyclohexyl) adipate, 1,2-epoxy-4 -Vinyl cyclohexane, 1,4-cyclohexane dimethanol diglycidyl ether, epoxy ethyl divinyl cyclohexane, diepoxy vinyl cyclohexane, 1,2,4-tri Epoxyethyl cyclohexane, limonene dioxide, polysiloxane oligomers containing alicyclic epoxy groups, etc. Among these, from the viewpoint of obtaining a cationic curable composition with excellent adhesion to aluminum die-cast products, PPS, etc., 3,4-epoxycyclohexylmethyl (3',4'-epoxy )Cyclohexane carboxylate, ε-caprolactone modified 3',4'-epoxycyclohexylmethyl, 3,4-epoxycyclohexane carboxylate, bis(3,4-epoxy ring Hexyl) adipate, 1,2-epoxy-4-vinylcyclohexane, or 1,4-cyclohexanedimethanol diepoxypropyl ether is preferred.

The commercial products of the alicyclic epoxy resin (B2) are not particularly limited, and examples include CELLOXIDE (registered trademark) 2081 (3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexyl) Alkyl carboxylate), CELLOXIDE (registered trademark) 2021P (3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate), CELLOXIDE (registered trademark) 2000 (1,2- Epoxy-4-vinylcyclohexane), CELLOXIDE (registered trademark) 3000 (1-methyl-4-(2-methylepoxyethyl)-7-oxabicyclo[4.1.0]heptane ), EHPE3150 (2,2-bis(hydroxymethyl)-1-butanol 1,2-epoxy-4-(2-epoxyethyl)cyclohexane adduct) (the above is provided by Daicel Co., Ltd.); TTA21 (manufactured by Jiangsu Tyco Chemical Co., Ltd.); X-40-2670, X-22-169AS, X-22-169B (manufactured by Shin-Etsu Chemical Co., Ltd.), etc., but not Limited to these.

The amount of (B) component added is not particularly limited, but with respect to 100 parts by mass of the total amount of the above (A) component and the above (B) component, the (B) component is preferably 10 to 95 parts by mass, and 20 to 90 The parts by mass is better, and even more preferably from 30 to 85 parts by mass. Moreover, relative to 100 parts by mass of the above-mentioned (A) component, the addition amount of the hydrogenated epoxy resin of the (B) component is not particularly limited, and it is preferably in the range of 50 to 700 parts by mass, and more preferably in the range of 100 to 600 parts by mass. Preferably, it is more preferably in the range of 150 to 550 parts by mass. Moreover, relative to 100 parts by mass of the above-mentioned (A) component, the amount of the alicyclic epoxy resin of the (B) component is not particularly limited, and it is preferably in the range of 20 to 300 parts by mass, and 50 to 250 parts by mass. The range is more preferable, and the range of 70 to 200 parts by mass is even more preferable. By making the addition amount of the component (B) component within the above-mentioned range, it is possible to provide a cationic curable composition having better adhesion to aluminum die-cast products, PPS, and the like.

Furthermore, when the hydrogenated epoxy resin (B1) and the alicyclic epoxy resin (B2) are used together as the (B) component, the alicyclic epoxy resin (B2) is based on 100 parts by mass of the hydrogenated epoxy resin (B1) The usage amount is preferably 10 to 300 parts by mass, more preferably 30 to 150 parts by mass, and even more preferably 40 to 100 parts by mass. When the hydrogenated epoxy resin (B1) and the alicyclic epoxy resin (B2) are used together as the (B) component, the ratio of the (A) component to the (B) component is as described above. When the usage amount of the component (B1) and the component (B2) is within the above range, the photocuring property and the low-temperature curing property have a good balance, and it is possible to maintain proper adhesiveness to various members.

＜(C) Ingredient＞ The component (C) of the present invention is a photocationic polymerization initiator that generates cationic species through irradiation with active energy rays. (C) The type of component is not particularly limited, and examples thereof include onium salts such as aromatic sulfonium salt and aromatic iodonium salt. (C) The component system may be used alone or in combination of two or more types (including two types). In addition, a cationic polymerization initiator having activity on both active energy rays and heat is regarded as the (C) component in the present invention.

With respect to the above-mentioned aromatic iodonium salt, for example, a salt containing an iodonium ion in which two groups bonded to an iodine atom are aryl groups can be mentioned. More specifically, for example, diphenylphosphonium tetrakis(pentafluorophenyl) borate, diphenylphosphonium hexafluorophosphate, diphenylphosphonium hexafluoroantimonate, bis(4-nonylphenyl) ) Iiodine hexafluorophosphate, 4-methylphenyl-4-(1-methylethyl)phenyl Iionium tetrakis (pentafluorophenyl) borate and the like.

As for the commercially available products of the above-mentioned aromatic iodonium salt, for example, Omnicat (registered trademark) 250 (manufactured by IGM Resins BV); Bluesil PI 2074 (manufactured by Rhodia, 4-methylphenyl-4-(1-methyl) Ethyl phenyl)-tetrakis (pentafluorophenyl) borate); B2380 (bis(4-tertiary butylphenyl) hexafluorophosphate), B2381, D2238, D2248, D2253, I0591 (above Manufactured by Tokyo Chemical Industry Co., Ltd.); WPI-113 (bis[4-n-alkyl (C10-13) phenyl] hexafluorophosphate), WPI-116 (bis[n-alkyl (C10-13) Phenyl) hexafluoroantimonate), WPI-169, WPI-170 (bis(4-tertiary butylphenyl) hexafluorophosphate), WPI-124 (bis(4-n-alkyl (C10 -13) Phenyl] iodotetrafluorophenyl borate) (the above are manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and the like.

The three groups bonded to the sulfur atom of the above-mentioned aromatic sulfonium salt are all aryl sulfonium ions. More specifically, for example, triphenyl sulfonium hexafluorophosphate, triphenyl sulfonium hexafluoroantimonate, triphenyl sulfonium tetrakis (pentafluorophenyl) borate, 4,4'-bis[two Phenyldihydrosulfide]diphenylsulfide-bishexafluorophosphate, 4,4'-bis[bis(β-hydroxyethoxy)phenyldihydrosulfide]diphenylsulfide-bishexafluoro Antimonate, 4,4'-bis[bis(β-hydroxyethoxy)phenyldihydrothio]diphenylsulfide-bishexafluorophosphate, 7-[bis(p-tolyl)dihydro Sulfuryl]-2-isopropylthioxanthone hexafluoroantimonate, 7-[di(p-tolyl)hydrosulfanyl]-2-isopropylthioxanthone tetrakis(pentafluorophenyl) borate, 4-Phenylcarbonyl-4'-diphenylhydrosulfide-diphenylsulfide-hexafluorophosphate, 4-(p-tertiary butylphenylcarbonyl)-4'-diphenyldihydrosulfide )-Diphenylsulfide-hexafluoroantimonate, 4-(p-tert-butylphenylcarbonyl)-4'-bis(p-tolyl)dihydrosulfide-diphenylsulfide-tetrakis(pentafluorobenzene) Yl)borate, 4-methylphenyl-4-(1-methylethyl)phenyl sulfonium-tetrakis(pentafluorophenyl)borate and the like. But it is not limited to these. These aromatic sulfonium salts can be used singly or as a mixture of two or more kinds (including two kinds).

As for the commercially available products of aromatic sulfonium salt, for example, Adoca Akles (registered trademark, the same below) SP-150, Adoca Akles SP-170, Adoca Akles SP-172 (manufactured by ADEKA company above); CPI-100P, CPI-101A, CPI-110B, CPI-200K, CPI-210S (manufactured by Sun Appro Co., Ltd. above); T1608, T1609, T2041 (tris(4-methylphenyl) hexafluorophosphate), T2042 ( Tri-tolyl acumin trifluoromethanesulfonate) (above manufactured by Tokyo Chemical Industry Co., Ltd.); Cyracure UVI-6990, Cyracure UVI-6974 (above manufactured by Union Carbide), DTS-200 (Green Chemical Co., Ltd.) Company manufacturing) and so on.

The blending amount of (C) component in the cationic curable composition of the present invention is not particularly limited, but it is in the range of 0.1-30 parts by mass relative to 100 parts by mass of the total amount of (A) and (B) components Inner is better, and it is more preferably in the range of 0.5 to 15 parts by mass. When the content of (C) component is 0.1 part by mass or more (including 0.1 part by mass) relative to 100 parts by mass of the total amount of (A) component and (B) component, sufficient photocuring properties can be obtained, and if it is 30 mass parts When it is less than 30 parts by mass (including 30 parts by mass), it is preferable from the viewpoint of excellent adhesion to aluminum die-cast products, PPS, and the like.

＜(D)Component＞ The component (D) of the present invention is a thermal cationic polymerization initiator, which generates a compound of cationic species by heating. The type is not particularly limited, and examples include: aromatic sulfonium-based thermal cationic polymerization initiators, aromatic sulphur-based thermal cationic polymerization initiators, thermal cationic polymerization initiators containing amine salts, etc., among them, available from From the viewpoint of a cationic curable composition with excellent adhesion to aluminum die-cast products and PPS while maintaining photocurability and low-temperature curability, a thermal cationic polymerization initiator containing an amine salt is preferred. These can be used alone or in combination of two or more types (including two types).

With regard to the thermal cationic polymerization initiator containing an amine salt, for example, a thermal cationic polymerization initiator containing a salt having a quaternary ammonium cation can be cited. More specifically, the salts with quaternary ammonium cations include, for example, salts composed of quaternary ammonium cations and borate anions, salts composed of quaternary ammonium cations and antimony anions, and quaternary ammonium cations and phosphate anions. The formed salt, etc. Among them, in terms of excellent adhesion to aluminum die-cast products, PPS, etc., a salt composed of a quaternary ammonium cation and a borate anion or a salt composed of a quaternary ammonium cation and an antimony anion is preferred.

With respect to the above-mentioned borate anion, for example, tetrafluoroborate anion, tetra(perfluorophenyl)borate anion, etc. can be mentioned. As for the antimony anion, for example, a tetrafluoroantimony anion, a tetra(perfluorophenyl)antimony anion, etc. can be mentioned. With respect to the above-mentioned phosphate anion, for example, hexafluorophosphate anion, trifluoro[tri(perfluoroethyl)] and the like can be mentioned.

As for the commercially available products of the thermal cationic polymerization initiator containing amine salt, for example, K-PURE (registered trademark, the same below) CXC-1612 (manufactured by King Industries, containing quaternary ammonium cation and borate Thermal cationic polymerization initiator for the salt formed by anion), K-PURE CXC-1821 (manufactured by King Industries, a thermal cationic polymerization initiator containing a salt formed by quaternary ammonium cation and antimonate anion), etc. .

As for the commercially available products of the above-mentioned aromatic sulfonium-based thermal cationic polymerization initiator, for example, San Aid (registered trademark, the same hereinafter) SI-60, San Aid SI-60L, San Aid SI-80, San Aid SI- 80L, San Aid SI-100, San Aid SI-100L, San Aid SI-180L, San Aid SI-B2A, San Aid SI-B3A (the above are manufactured by Sanxin Chemical Industry Co., Ltd.); CI-2624 (Japan Soda Co., Ltd.), etc. Furthermore, as for the above-mentioned aromatic iodonium-based thermal cationic polymerization initiator, for example, diphenyl iodonium trifluoromethanesulfonate (reagent) and the like can be cited.

The compounding amount of the (D) component in the cationic curable composition of the present invention is not particularly limited, but it is 0.1-30 parts by mass relative to 100 parts by mass of the total amount of the above-mentioned (A) component and (B) component It is preferably in the range, and more preferably in the range of 0.5 to 15 parts by mass. Relative to the total amount of the above-mentioned (A) component and (B) component 100 parts by mass, when the blending amount of (D) component is 0.1 parts by mass or more (including 0.1 parts by mass), sufficient low-temperature curability can be obtained, and it is 30 When it is less than or equal to 30 parts by mass (including 30 parts by mass), it is preferable from the viewpoint of excellent adhesion to aluminum die-cast products, PPS, and the like.

＜(E) Ingredient＞ The (E) component of the present invention is not particularly limited if it is a polycaprolactone polyol having trifunctional or higher (including trifunctional) hydroxyl groups and a molecular weight of 1700 or lower (including 1700). The component (E) of the present invention can be combined with other components of the present invention, and by setting it in the specified blending range described below, it can maintain light curability and low-temperature curability while having adhesion to aluminum die-cast products, PPS, etc. The remarkable effect of excellent performance. (E) The molecular weight of the component is more preferably in the range of 200-1500, particularly preferably in the range of 250-1000. The molecular weight is measured according to the hydroxyl value of polycaprolactone polyol measured in JIS K1557-1:2007.

The said (E) component is not specifically limited, For example, the compound etc. which are represented by the following general formula (2) are mentioned.

R-[O[CO(CH ₂ ) ₅ O] _n H] _m (2) (wherein R is a trivalent or tetravalent aliphatic hydrocarbon group, n is in the range of 2 to 500, and m is 3 or 4. )

(E) Specific compound systems of the component include, for example, polycaprolactone triol, polycaprolactone tetraol, and the like. Moreover, as for the commercially available products of the component (E), Praxel (registered trademark, the same hereinafter) 303, Praxel 305, Praxel 308, Praxel 309, Praxel 312, Praxel 400 (manufactured by Daicel Co., Ltd.) and the like can be mentioned.

The cationic curable composition of the present invention is characterized in that the content of (E) component is 12-100 parts by mass, and 15-70 parts by mass relative to 100 parts by mass of the total amount of (A) component and (B) component Preferably, it is more preferably 17-50 parts by mass. Within the above range, a cationic curable composition having excellent adhesion to aluminum die-cast products, PPS, etc., can be obtained while maintaining light curability and low-temperature curability.

＜Optional ingredients＞ Moreover, within the range that does not impair the characteristics of the present invention, the cationic curable composition of the present invention can be appropriately blended with silane coupling agents, colorants, oxetane compounds, vinyl ether compounds, sensitizers, and peroxides. , Thiol compounds, storage stabilizers and other additives. Moreover, within the range that does not impair the characteristics of the present invention, the cationic curable composition of the present invention can be formulated in an appropriate amount: calcium carbonate, magnesium carbonate, titanium oxide, magnesium hydroxide, talc, silica, alumina, glass, and hydroxide. Inorganic fillers such as aluminum, boron nitride, aluminum nitride and magnesium oxide with an average particle size of 0.001-100μm; conductive particles such as silver: flame retardant; rubber such as acrylic rubber and silicon rubber; plasticizer, organic solvent; Antioxidants such as phenolic antioxidants and phosphorus antioxidants; light stabilizers; ultraviolet absorbers; defoamers; foaming agents; release agents; leveling agents; rheology modifiers; tackifiers; hardening retarders; Polyimide resins, polyimide resins, phenoxy resins, cyanate esters, poly(meth)acrylate resins, polyurethane resins, polyurea resins, polyester resins, Various additives such as polymers such as polyvinyl butyral resin, styrene-butadiene-styrene copolymer (SBS), styrene-ethylene-butene-styrene copolymer (SEBS), and thermoplastic elastomers. By these additions, a cationic curable composition with excellent resin strength, adhesive strength, flame retardancy, thermal conductivity, handleability, etc., and its cured product can be obtained.

The silane coupling agent improves the compatibility of the components (A) to (E). In addition to improving the low-temperature curability, it can also provide a compound of a cationic curable composition with excellent adhesion to aluminum die-cast products, PPS, and the like. The silane coupling agent is not particularly limited. Specific examples include 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-ring Oxypropoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane and other glycidoxy-containing silane coupling agents; vinyl tris(β-methoxyethoxy Group) silane, vinyl triethoxy silane, vinyl trimethoxy silane and other vinyl-containing silane coupling agents; γ-methacryloxy propyl trimethoxy silane, etc. containing (meth)acrylic group Silane coupling agent; N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethyl Silane coupling agents containing amine groups such as oxysilanes; and other γ-mercaptopropyl trimethoxy silanes, γ-chloropropyl trimethoxy silanes, etc. Among them, the glycidoxy-containing silane coupling agent is suitable. Among the glycidoxy-containing silane coupling agents, 3-glycidoxypropyltrimethoxysilane, 3 -Glycidoxypropyl triethoxysilane is preferred. These silane coupling agents may be used alone or in combination of two or more types (including two types). Moreover, the amount of the silane coupling agent is not particularly limited, but it is preferably in the range of 0.1-30 parts by mass and 0.5-15 parts by mass relative to 100 parts by mass of the total of the components (A) and (B). Better.

Examples of the colorant system include pigments, dyes, etc. Among them, from the viewpoint of durability, pigments are preferred. Furthermore, among the pigments, black pigments are preferred from the viewpoint of excellent hiding properties. Examples of black pigments include carbon black, black titanium oxide, copper chrome black, cyan black, aniline black, and the like. Among these, from the viewpoint of covering properties and dispersibility to the (A) component of the present invention, carbon black is preferred. The compounding amount of the coloring agent in the cationic curable composition of the present invention is not particularly limited, but it is preferably in the range of 0.01-30 parts by mass relative to 100 parts by mass of the total amount of component (A) and component (B). It is more preferably in the range of 0.05 to 10 parts by mass, and more preferably in the range of 0.1 to 5 parts by mass.

Examples of the oxetane compound system include 3-ethyl-3-hydroxymethyloxetane, 3-(methyl)allyloxymethyl-3-ethyloxetane, (3 -Ethyl-3-oxocyclobutylmethoxy)methylbenzene, 4-fluoro-[1-(3-ethyl-3-oxocyclobutylmethoxy)methyl]benzene, [1-(3-ethyl -3-oxocyclobutylmethoxy)ethyl]phenyl ether, isobutoxymethyl(3-ethyl-3-oxocyclobutylmethyl)ether, 2-ethylhexyl(3-ethyl-3- Oxycyclobutyl methyl) ether, ethyl diethylene glycol (3-ethyl-3-oxocyclobutyl methyl) ether, tetrahydrofurfuryl (3-ethyl-3-oxocyclobutyl methyl) ether, tetrabromobenzene Base (3-ethyl-3-oxocyclobutyl methyl) ether, 2-tetrabromophenoxy ethyl (3-ethyl-3-oxocyclobutyl methyl) ether, pentachlorophenyl (3-ethyl- 3-oxocyclobutyl methyl) ether, pentabromophenyl (3-ethyl-3-oxocyclobutyl methyl) ether, ethylene glycol bis(3-ethyl-3-oxocyclobutyl methyl) ether, triethylenedi Alcohol bis(3-ethyl-3-oxocyclobutyl methyl) ether, tetraethylene glycol bis(3-ethyl-3-oxocyclobutyl methyl) ether, trimethylolpropane tris(3-ethyl-3 -Oxycyclobutyl methyl) ether, neopentyl erythritol tris (3-ethyl-3-oxocyclobutyl methyl) ether, neopentyl erythritol tetrakis (3-ethyl-3-oxocyclobutyl methyl) ether, two new Pentyleneerythritol tetrakis (3-ethyl-3-oxocyclobutyl methyl) ether, di-trimethylolpropane tetrakis (3-ethyl-3-oxocyclobutyl methyl) ether and the like. Examples of commercially available products of oxetane compounds include: Aron Oxetane (registered trademark, the same hereinafter) OXT-212, Aron Oxetane OXT-221, Aron Oxetane OXT-213, Aron Oxetane OXT-101 (Toa Synthetic Co., Ltd.) Company manufacturing) and so on.

Examples of vinyl ether compounds include: 1,4-butanediol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, tetraethylene glycol divinyl ether, normal Propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexyl vinyl ether, 2-hydroxyethyl vinyl ether , Diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, 2-(2-vinyloxyethoxy) ethyl acrylate, 2-(2-vinyloxyethoxy) methacrylate Ethyl and so on. Commercial products of vinyl ether compounds include, for example: NPVE, IPVE, NBVE, IBVE, 2-EHVE, CHVE (manufactured by Nippon Carbide Industrial Co., Ltd.); HEVE, DEGV, HBVE (manufactured by Maruzen Petrochemical Co., Ltd.); VEEA, VEEM (the above are manufactured by Nippon Catalyst Co., Ltd.), etc.

The sensitizer system may include, for example: 9- ketone, anthrone, dibenzocycloheptanone, fen, 2-bromo fen, 9-bromo fen, 9,9-dimethyl fen, 2-fluoro fen, 2 -Iodopyridium, 2-Pyramide, 9-Pyridine alcohol, 2,7-Dibromopyridinium, 9-Aminopyridinium hydrochloride, 2,7-Diaminopyrimidine, 9,9'-spirobis[9H-茀], 2-Hydrocarboxaldehyde, 9-Hydroxycarbinol, 2-Acetyl phosphonium, Diphenyl ketone, Diethoxyacetophenone, 2-Hydroxy-2-methyl-1-phenylpropane- 1-ketone, benzyl dimethyl ketal, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxy-cyclohexyl-phenyl-ketone, 2 -Methyl-2-N-morpholinyl (4-thiomethylphenyl) propane-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl) ) Butanone, 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]acetone oligomer, nitro compound, pigment, etc. The amount of the sensitizer added is not particularly limited, and can be appropriately determined with reference to the absorption wavelength and the molar absorption coefficient.

＜Hardening method＞ The cationic curable composition system of the present invention can be cured by irradiation with active energy rays (photocurable). Furthermore, the cationic curable composition of the present invention can be cured under low-temperature conditions (low-temperature curability). Furthermore, the cationic curable composition of the present invention can be cured under the irradiation of active energy rays and under low temperature conditions. Here, the active energy ray system includes, for example, ultraviolet rays, electron beams, visible rays, and the like. The wavelength of the active energy rays is preferably 150-830 nm, more preferably 200-600 nm, and even more preferably 250-380 nm.

Moreover, the above-mentioned "low temperature" refers to the temperature at which the cationic curable composition of the present invention can be cured at a lower temperature, and actually corresponds to the heating conditions of the curing method of the cationic curable composition of the present invention. The heating conditions (curable temperature) are not particularly limited. For example, they are 45°C to 150°C, preferably 45°C or higher (including 45°C) and less than 150°C, and 50°C or higher (including 50°C) and The temperature below 140°C is more preferred, and the temperature above 55°C (including 55°C) and below 130°C is even more preferred. When the heating and curing temperature is above 45℃ (including 45℃) and less than 150℃, the heating time is preferably within the range of 3 minutes or more (including 3 minutes) and less than 5 hours, and 10 minutes or more (including 10 minutes) The range of less than 3 hours (including 3 hours) is more preferable. Furthermore, the cationic curable composition of the present invention can be cured by irradiation with active energy rays. The active energy ray system at this time can be exemplified by ultraviolet rays, electron beams, visible rays, etc., but there is no particular limitation. The active energy ray accumulated light amount of, for example, 300 ~ 100000mJ / cm ^2, to 500 ~ 50000mJ / cm ² preferably, at 1000 ~ 10000mJ / cm ² more preferably, at 2000 ~ 5000mJ / cm ² and more preferably to 3000mJ / cm ² is particularly good. The wavelength of the active energy rays is preferably 150-830 nm, more preferably 200-600 nm, and even more preferably 250-380 nm.

＜Connecting method＞ The cationic curable composition of the present invention can be used for adhesion of adherends. Specific bonding methods include, for example, the following steps of arranging the cationic curable composition of the present invention between a pair of adherends: 1. irradiating the cationic curable composition with active energy rays; 2. After irradiation, heat the adherend in step 3 at a temperature above 45°C (including 45°C) and less than 150°C. Hereinafter, each step will be explained.

[step 1] The cationic curable composition of the present invention is arranged between a pair of adherends. Specifically, for example, a cationic curable composition is placed on one adherend by dropping or coating, and the other adherend is placed on the cationic curable composition of the placement, and a pair of adherends is arbitrarily arranged. Align and place. At the time of coating, for example, a coating method used for a conventional sealant or adhesive can be used. Specific coating methods include, for example, dispensing, spraying, inkjet, screen printing, gravure printing, dip coating, spin coating, etc. using an automatic coating machine. The adhered system can use, for example, metal, glass, plastic, etc. However, from the viewpoint of good compatibility with the cationic curable composition of the present invention, preferred ones include, for example, aluminum die-cast products and PPS.

[Step 2] The cationic curable composition prepared in step 1 is irradiated with active energy rays to cure the cationic curable composition, and a pair of adherends are temporarily bonded. The curing of the cationic curable composition irradiated with active energy rays is particularly performed on the surface of the composition and its vicinity. The irradiation system can be performed directly on the cationic curable composition placed, especially when the adherend is transparent or translucent, indirectly through the adherend.

[Step 3] After the active energy ray is irradiated in step 2, the configured cationic curable composition is further heated at a predetermined temperature to completely harden the cationic curable composition and completely bond the pair of adherends (main bonding). The curing of the cationic curable composition by heating is carried out especially in the interior of the composition outside the surface of the composition and its vicinity. Before the curing reaction by heating in step 3, when the curing reaction by irradiation in step 2 above is performed first, the curing (crosslinking) reaction of the resin composition starts quickly, and the curing reaction by heating in the subsequent step 3 , The reaction inside the cationic curable composition that is not exposed to active energy rays proceeds quickly, and complete curing of the cationic curable composition can be achieved. The heating temperature in step 3 is preferably 45-150°C, more preferably 45°C or more (including 45°C) and less than 140°C, and more preferably 50°C or more (including 50°C) and less than 130°C, especially It is particularly preferred that the temperature is above 55°C (including 55°C) and less than 125°C.

＜Use of cationic curable composition＞ The use of the cationic curable composition of the present invention is not particularly limited, and examples thereof include adhesives, sealants, coating agents, potting agents, conductive adhesives, and the like. Moreover, the application fields of the cationic curable composition of the present invention are not particularly limited. Examples include: switch parts, headlights, engine internal parts, electrical parts, driving engines, brake fuel tanks, and other automotive fields; liquid crystal displays, Electro-luminescence, touch panels, plasma displays, light-emitting diode display devices and other flat-panel display fields; video disks, CDs, DVDs, MDs, camera lenses, hard disk peripheral components, Blu-ray discs and other recording fields; electronic components, circuits, relays , Electrical contact or semiconductor components and other sealing materials, die-bonding agents, conductive adhesives, anisotropic conductive adhesives, layer indirect adhesives for multi-layer substrates including build-up substrates, and other electronic materials; photographic molds such as CMOS image sensors Group; lithium batteries, manganese batteries, alkaline batteries, nickel batteries, fuel cells, silicon solar cells, dye-sensitized solar cells, organic solar cells and other battery fields; optical switch peripherals and optical connectors in optical communication systems Peripheral optical fiber materials, optical passive components, optical circuit components, and photoelectric integrated circuit peripherals and other optical parts fields; mobile terminal devices; construction fields, aviation fields, etc.

The cationic curable composition of the present invention can maintain light curability and low-temperature curability, and at the same time has excellent adhesion with aluminum die castings, PPS, etc., and can be particularly suitable as an adhesive for assembly of electronic/electric parts modules, automobile parts, etc. Agent. The above-mentioned electronic/electrical component modules include: display housing, computer housing, optical reading head module, mobile machine housing, HDD housing, camera module, projector housing, CD, DVD player housing, radiator, relay , Connectors, module boxes, etc. Moreover, the above-mentioned vehicle parts series may include: ECU housing, vehicle camera module, vehicle sensor module (vehicle radar module, driver module, etc.), condenser housing, power supply module, connector, ignition coil, etc. . [Example]

The following examples illustrate the present invention in detail, but the present invention is not limited by the following examples.

<Preparation of cationic curable composition>

• Example 1 Add 20 parts by mass of aromatic bisphenol F type epoxy resin (a1) (manufactured by Mitsubishi Chemical Corporation; jER807ST) as component (A), (B) component hydrogenated bisphenol A epoxy resin (b1) (manufactured by Mitsubishi Chemical Corporation; jER YX-8000) 50 parts by mass, and 3',4'-epoxycyclohexylmethyl 3,4 -Epoxycyclohexane carboxylate (b2) (manufactured by Daicel Co., Ltd.; Celloxide 2021P) 30 parts by mass, (C) Component 4-methylphenyl-4-(1-methylethyl)phenylphonium-tetrakis(pentafluorophenyl)borate (c1) (manufactured by Rodia; Bluesil PI-2074) 3 Mass parts, 2 parts by mass of a thermal cationic polymerization initiator (d1) (manufactured by King Industries; K-PURE CXC-1821) containing a salt of a quaternary ammonium cation and a borate anion as the component (D), (E) 25 parts by mass of polycaprolactone triol (e1) (manufactured by Daicel Co., Ltd.; Placcel 305) having a trifunctional hydroxyl group and a molecular weight of 550 as the component, 2 parts by mass of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent were mixed with a planetary mixer at room temperature (25°C) under shading for 60 minutes to obtain the cationic curable composition of Example 1 .

• Example 2 In Example 1, except that 20 parts by mass of the component (a1) was changed to 50 parts by mass, the component (b1) was not used, and 30 parts by mass of the component (b2) was changed to 50 parts by mass, the same procedure as in Example 1 was carried out. It was prepared by the same operation, and the cationic curable composition of Example 2 was obtained.

• Example 3 In Example 1, except that 50 parts by mass of the component (b1) was changed to 80 parts by mass and the component (b2) was not used, the same operation as in Example 1 was performed to prepare the cation curable composition of Example 3 Things.

•Comparative example 1 In Example 1, except that (a1) was removed and 50 parts by mass of the component (b1) was changed to 70 parts by mass, the same operation as in Example 1 was performed to prepare the cation curable composition of Comparative Example 1.

•Comparative example 2 In Example 1, except that (e1) was removed, the same operation as in Example 1 was performed to prepare, and the cation curable composition of Comparative Example 2 was obtained.

•Comparative example 3 In Example 1, except that 25 parts by mass of the component (e1) was changed to 10 parts by mass, the same operation as in Example 1 was performed to prepare the cation curable composition of Comparative Example 3.

•Comparative example 4 In Example 1, except that the component (e1) was changed to a polycaprolactone polyol (e'1) (manufactured by Daicel Co., Ltd.; Placcel 205) having a bifunctional hydroxyl group and a molecular weight of 500, the same as in the examples It was prepared by the same operation as in 1, and the cationic curable composition of Comparative Example 4 was obtained.

•Comparative example 5 In Example 1, except that the component (e1) was changed to a polycaprolactone polyol (e'2) (manufactured by Daicel Co., Ltd.; Placcel 320) having a trifunctional hydroxyl group and a molecular weight of 2000, the same as in the example was performed. It was prepared by the same operation as in 1, and the cation curable composition of Comparative Example 5 was obtained.

•Comparative example 6 In Example 1, except that the component (d1) was removed, the same operation as in Example 1 was performed to prepare the cation curable composition of Comparative Example 6.

<Photocuring test> 0.01 g of the cationic curable composition was dropped on a glass test piece of 25 mm in width × 100 mm in length × 5 mm in thickness. Then, through an ultraviolet irradiation device (manufactured by Jatec Co., Ltd.; model: JUL-M-433AN-05, ultraviolet wavelength: 365 nm) ^{, an active energy ray with a cumulative light amount of 3000 mJ/cm 2} was irradiated to obtain a test piece. Next, a glass rod with a sharp tip was brought into contact with the test piece, and the curability of the cationic curable composition was evaluated based on the following criteria. In the following criteria, if it is ○, it can be said that the curability is good.

[Assessment criteria] ○: No attachments on the stick ×: There is an attachment on the stick.

＜Low temperature hardening test＞ 0.1g of each cationic curable composition was dropped on a hot plate set at 100°C. After 30 minutes, a glass rod with a sharp tip was brought into contact with the cured product, and the curability of the composition was evaluated according to the following criteria. In the following criteria, if it is ○, it can be said that the low-temperature hardenability is good.

[Assessment criteria] ○: No attachments on the stick ×: There is an attachment on the stick.

＜Tensile shear bonding strength test for aluminum die castings＞ The cation curable composition of the examples and the comparative examples was coated on a test piece made of ADC12, an aluminum die-cast product having a width of 25 mm × a length of 100 mm × a thickness of 1 mm. Then, another aluminum die-cast ADC12 test piece was attached and fixed with a clip so that the surface of the outer package was 25 mm×10 mm. Then, this was cured in a hot-air drying oven set at 120°C for 60 minutes to obtain a test piece. Then, using a test piece, in accordance with JIS K6850: 1999, a universal tensile tester (tensile speed 50 mm/min.) was used to measure the tensile shear bond strength (unit: MPa) at 25°C. The tensile shear strength is the value at the maximum strength. Furthermore, in order to use the cationic curable composition of the present invention as an adhesive for assembling electronic/electric parts modules, vehicle parts, etc., the tensile shear bonding strength is preferably 5.0 MPa or more (including 5.0 MPa).

＜Tensile shear adhesion strength test of polyphenylene sulfide (PPS)＞ The cationic curable composition of the examples and the comparative examples was coated on a test piece made of PPS with a width of 25 mm × a length of 100 mm × a thickness of 1 mm. Then, another test piece made of PPS was attached and fixed with a clip so that the surface of the outer package was 25 mm×10 mm. Then, this was cured in a hot-air drying oven set at 120°C for 60 minutes to obtain a test piece. Then, using a test piece, in accordance with JIS K6850: 1999, a universal tensile tester (tensile speed 50 mm/min.) was used to measure the tensile shear bond strength (unit: MPa) at 25°C. The tensile shear strength is the value at the maximum strength. Furthermore, in order to use the cationic curable composition of the present invention as an adhesive for assembling electronic/electric parts modules, vehicle parts, etc., the tensile shear bonding strength is preferably 5.0 MPa or more (including 5.0 MPa).

The above test results are summarized in Table 1 below. In addition, "-" in Table 1 below indicates that it has not been measured.

[Table 1] Tensile shear bonding strength to aluminum die casting (MPa) Tensile shear bond strength to PPS (MPa) Light hardening Low temperature hardening Example 1 5.66 5.42 ○ ○ Example 2 10.11 5.96 ○ ○ Example 3 16.73 5.19 ○ ○ Comparative example 1 5.52 4.30 ○ ○ Comparative example 2 2.46 4.23 ○ ○ Comparative example 3 3.65 3.80 ○ ○ Comparative example 4 1.86 - ○ ○ Comparative example 5 3.38 - ○ ○ Comparative example 6 - - ○ X

As is apparent from Table 1 above, the cationic curable compositions of Examples 1 to 3 maintain light curability and low-temperature curability, and have excellent adhesion to aluminum die castings, PPS, and the like.

Comparative Example 1 is a cationic curable composition that does not contain the component (A) of the present invention, and it can be seen that the adhesiveness to PPS is poor. In addition, Comparative Example 2 is a cationic curable composition that does not contain the (E) component of the present invention, and it can be seen that the adhesiveness to aluminum die castings and PPS is poor. In addition, Comparative Example 3 is a cationic curable composition when the addition amount is not within the predetermined range of the component (E) of the present invention, and it can be seen that the adhesiveness to aluminum die castings and PPS is poor. In addition, Comparative Examples 4 and 5 are cation-curable compositions when a polyol that is not the component (E) of the present invention is used, and it can be seen that the adhesiveness to aluminum die-casts is poor. Comparative Example 6 is a cationic curable composition that does not contain the component (D) of the present invention, and the result of the low-temperature curability test is inferior. [Industrial availability]

The cationic curable composition of the present invention maintains light curability and low-temperature curability, and has excellent adhesion to aluminum die-casting parts and PPS, so it can be applied to a wide range of applications such as the bonding of module components of electrical and electronic parts. Field, can be applied in industry.

This application is based on the Japanese Patent Application No. 2019-223752 filed on December 11, 2019, and is incorporated into this specification with reference to all the contents disclosed.

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Claims (12)

A cationic curable composition containing the following (A) to (E) components, and containing 12-100 parts by mass of (E) component relative to 100 parts by mass of the total amount of (A) component and (B) component , (A)Component: Aromatic epoxy resin (B) Component: at least one of hydrogenated epoxy resin (B1) and alicyclic epoxy resin (B2) (C)Component: photocationic polymerization initiator (D)Component: Thermal cationic polymerization initiator (E) Component: a polycaprolactone polyol having trifunctional or higher (including trifunctional) hydroxyl groups and a molecular weight of 1700 or lower (including 1700). The cationic curable composition according to claim 1, which contains 10 to 80 parts by mass of the component (B) relative to 100 parts by mass of the total amount of the component (A) and the component (B). The cationic curable composition of claim 1 or 2, wherein the above-mentioned component (D) is selected from the group consisting of an aromatic sulfonium-based thermal cationic polymerization initiator, an aromatic sulfonium-based thermal cationic polymerization initiator, and a thermal At least one of the group of cationic polymerization initiators. The cationic curable composition according to any one of claims 1 to 3, wherein the above-mentioned component (D) contains a thermal cationic polymerization initiator having a salt of a quaternary ammonium cation. The cationic curable composition according to any one of claims 1 to 4, wherein the above-mentioned component (C) contains at least one of an aromatic iodonium salt and an aromatic sulphur salt. The cationic curable composition according to any one of claims 1 to 5, wherein the above component (A) is selected from the group consisting of aromatic bisphenol A epoxy resin, aromatic bisphenol F epoxy resin, and aromatic At least one of the group of bisphenol E epoxy resins. The cationic curable composition according to any one of claims 1 to 6, wherein the component (B) only contains any one of the hydrogenated epoxy resin (B1) and the alicyclic epoxy resin (B2). The cationic curable composition according to any one of claims 1 to 6, wherein the component (B) includes the hydrogenated epoxy resin (B1) and the alicyclic epoxy resin (B2). The cationic curable composition according to any one of claims 1 to 8, which is used as an adhesive. The cationic curable composition according to any one of claims 1 to 9, which is used as an adhesive when the adherend is aluminum die-cast or PPS. A hardened material is a hardened material of the cationic curable composition according to any one of claims 1 to 10. A joined body which is formed by using the cationic curable composition of any one of claims 1 to 10 and adhering to the adherend.