Curable resin composition

Abstract

The present invention provides a curable resin composition comprising: (A) an epoxy resin; (B1) a compound having a ring structure and having 3 or 4 mercapto groups; (B2) a compound not having a ring structure, and having 2 or 3 mercapto groups; and (C) a calcium carbonate having a BET specific surface area of 5 m2 / g or more.

Description

Curable resin composition

[0001] The present invention relates to a curable resin composition.

[0002] Curable resin compositions are used in a variety of applications. For example, in the manufacture of electronic devices such as camera modules, curable resin compositions are sometimes used to bond components thereof. For example, Patent Document 1 describes a curable resin composition having excellent adhesion, which is a composition comprising a curable resin and a polymer having a BET specific surface area of ​​5 m. ２ A curable resin composition is disclosed that contains calcium carbonate having a viscosity of 1 / 2 g or more and a curing agent.

[0003] JP 2023-129848 A

[0004] In order to improve the resistance of electronic devices such as camera modules to impacts such as those caused by their being dropped (hereinafter referred to as "impact resistance"), there is a demand for curable resin compositions that can form cured products with a low elastic modulus as adhesives for bonding components of electronic devices. However, cured products with a low elastic modulus tend to be easily distorted and broken when stress is applied, which reduces adhesion, making it difficult to achieve both a low elastic modulus and high adhesion. Furthermore, in order to improve the impact resistance of electronic devices, there is a demand for curable resin compositions that can form cured products that are easy to stretch as adhesives for bonding components of electronic devices.

[0005] The present invention has been made in light of the above-mentioned circumstances, and an object of the present invention is to provide a curable resin composition that can form a cured product having a low elastic modulus, high adhesion to metals, and high elongation.

[0006] The present invention can achieve the above object as follows: [1] A composition comprising the following components (A) to (C): (A) an epoxy resin, (B1) a compound having a cyclic structure and three or four mercapto groups, (B2) a compound having no cyclic structure and two or three mercapto groups, and (C) a compound having a BET specific surface area of ​​5 m ２ [2] A curable resin composition comprising calcium carbonate having a BET specific surface area of ​​30 m / g or more. ２ / g or more. [3] The curable resin composition according to [1] above, wherein the molar ratio of mercapto groups in component (B2) to mercapto groups in component (B1) is 30 / 70 to 70 / 30. [4] The curable resin composition according to any one of [1] to [3] above, wherein the mass ratio of component (C) to component (B1) is 30 / 70 to 60 / 40. [5] The curable resin composition according to [2] above, wherein the mass ratio of component (D) to component (B1) is 10 / 90 to 30 / 70. [6] The curable resin composition according to any one of [1] to [5] above, wherein component (B2) has an ether bond but does not have an ester bond. [7] The curable resin composition according to any one of [1] to [6], wherein the modulus of elasticity of a 100 μm-thick cured product obtained by curing the curable resin composition at 80° C. for 60 minutes is 2000 MPa or less. [8] The curable resin composition according to any one of [1] to [7], wherein the number of mercapto groups in component (B2) is 2. [9] An adhesive comprising the curable resin composition according to any one of [1] to [8].

[10] The adhesive according to [9], which is used for bonding components of a camera module.

[0007] According to the present invention, a curable resin composition can be obtained that can form a cured product having a low modulus of elasticity, high adhesion to metals, and high elongation.

[0008] The present invention will be described below in order. Note that the descriptions in this specification can be combined with each other unless it is clear that they cannot be combined.

[0009] The curable resin composition of the present invention comprises the following components (A) to (C): (A) an epoxy resin, (B1) a compound having a cyclic structure and three or four mercapto groups, (B2) a compound having no cyclic structure and two or three mercapto groups, and (C) a compound having a BET specific surface area of ​​5 m ２ / g or more of calcium carbonate.

[0010] Components (A) to (C) may each be used alone or in combination of two or more. When two or more components (A) are used, the "content of component (A)" means the "total content of two or more components (A)." The "content of component (C)" has the same meaning as the "content of component (A)."

[0011] <(A) Epoxy Resin> In the present invention, an epoxy resin is used as component (A). As component (A), for example, a commercially available epoxy resin available from Mitsubishi Chemical Corporation or the like can be used.

[0012] In this specification, the term "epoxy resin" refers to a compound having an epoxy group that can form a cured product by thermal reaction with a curing agent (i.e., a thermosetting resin having an epoxy group). The epoxy resin preferably has two or more epoxy groups.

[0013] The epoxy equivalent of the epoxy resin is preferably 50 to 700 g / eq, more preferably 100 to 500 g / eq. In this specification, the "epoxy equivalent of the epoxy resin" means the number of grams of epoxy resin containing 1 gram equivalent of epoxy groups (unit: g / eq). The epoxy equivalent can be measured according to the method specified in JIS K 7236. Theoretically, the epoxy equivalent can be calculated by dividing the molecular weight of the epoxy resin by the number of epoxy groups contained in the resin.

[0014] Examples of epoxy resins include bisphenol A type epoxy resins, hydrogenated bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD ​​type epoxy resins, bisphenol S type epoxy resins, dicyclopentadiene type epoxy resins, biphenyl type epoxy resins, biphenyl aralkyl type epoxy resins, naphthol type epoxy resins, naphthalene type epoxy resins, phosphorus-containing epoxy resins, aromatic glycidylamine type epoxy resins, alicyclic epoxy resins, oxazolidone ring type epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, and bisphenol A novolac type epoxy resins.

[0015] For ease of handling, component (A) preferably contains a liquid epoxy resin. Note that "liquid epoxy resin" refers to an epoxy resin that is liquid at room temperature (25°C). The amount of the liquid epoxy resin relative to component (A) is preferably 40% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, and preferably 100% by mass or less.

[0016] Component (A) preferably contains a bisphenol A-type epoxy resin, more preferably a liquid bisphenol A-type epoxy resin. The bisphenol A-type epoxy resin may be modified. In this specification, "bisphenol A-type epoxy resin" refers to an epoxy resin having a bisphenol A skeleton. Therefore, modified bisphenol A-type epoxy resins are also included in the "bisphenol A-type epoxy resin" in this specification as long as they have a bisphenol A skeleton. The amount of bisphenol A-type epoxy resin is preferably 5% by mass or more, more preferably 20% by mass or more, and even more preferably 40% by mass or more, and preferably 100% by mass or less, relative to component (A).

[0017] From the viewpoint of maintaining the paste form of the curable resin composition, the content of component (A) is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, and is preferably 75% by mass or less, more preferably 70% by mass or less, even more preferably 65% ​​by mass or less, based on the entire curable resin composition.

[0018] <(B1) Compound Having a Cyclic Structure and Three or Four Mercapto Groups> <(B2) Compound Having No Cyclic Structure and Two or Three Mercapto Groups> The present invention uses a compound having a cyclic structure and three or four mercapto groups as component (B1), and a compound having no cyclic structure and two or three mercapto groups as component (B2). Both component (B1) and component (B2) function as curing agents for component (A) (epoxy resin).

[0019] When component (B1) alone is used, the resulting cured product tends to have an increased elastic modulus and a decreased elongation. On the other hand, when component (B2) alone is used, the resulting cured product tends to have a decreased adhesive strength. In contrast, the curable resin composition of the present invention, which uses component (B1) and component (B2) in combination, can form a cured product having a low elastic modulus, high adhesive strength to metals, and high elongation. It is believed that the combined use of component (B1) having a cyclic structure and component (B2) not having a cyclic structure can improve various properties in a balanced manner.

[0020] From the viewpoint of achieving a low elastic modulus and high elongation of the resulting cured product, the mercapto equivalent of component (B1) is preferably 70 to 300 g / eq, more preferably 90 to 250 g / eq, and even more preferably 100 to 200 g / eq. In this specification, "mercapto equivalent" means the mass (g) per equivalent of a mercapto group of a compound having a mercapto group (unit: g / eq). Theoretically, the mercapto equivalent can be calculated by dividing the molecular weight of the compound having a mercapto group by the number of mercapto groups contained in the compound.

[0021] Examples of the component (B1) include tris(3-mercaptopropyl)isocyanurate, tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate, and tetrahydro-1,3,4,6-tetrakis(3-mercaptopropyl)-imidazo[4,5-d]imidazole-2,5(1H,3H)-dione.

[0022] Component (B1) is preferably at least one selected from tris(3-mercaptopropyl)isocyanurate and tetrahydro-1,3,4,6-tetrakis(3-mercaptopropyl)-imidazo[4,5-d]imidazole-2,5(1H,3H)-dione, more preferably tris(3-mercaptopropyl)isocyanurate or tetrahydro-1,3,4,6-tetrakis(3-mercaptopropyl)-imidazo[4,5-d]imidazole-2,5(1H,3H)-dione, and even more preferably tris(3-mercaptopropyl)isocyanurate.

[0023] From the viewpoint of providing a cured product with high adhesion to metals, the mercapto equivalent of component (B2) is preferably 50 to 270 g / eq, more preferably 70 to 220 g / eq, and even more preferably 80 to 170 g / eq.

[0024] From the viewpoints of flexibility and moist heat resistance of the resulting cured product, it is preferable that component (B2) has an ether bond (—O—) and does not have an ester bond (—CO—O—). Furthermore, from the viewpoints of the reactivity of component (B2) and the flexibility of the resulting cured product, the number of mercapto groups in component (B2) is preferably 2.

[0025] Examples of component (B2) include 3,6-dioxa-1,8-octanedithiol, 1,4-bis(3-mercaptobutyryloxy)butane, trimethylolpropane tris(3-mercaptobutyrate), trimethylolethane bis(mercaptoacetate), trimethylolethane bis(3-mercaptopropionate), trimethylolethane bis(3-mercaptobutyrate), trimethylolethane bis(4-mercaptobutyrate), trimethylolpropane bis(mercaptoacetate), trimethylolpropane bis(3-mercaptopropionate), trimethylolpropane bis(3-mercaptobutyrate), trimethylolpropane bis(4-mercaptobutyrate), pentaerythritol tris(mercaptoacetate), pentaerythritol tris(3-mercaptopropionate) ), pentaerythritol tris(3-mercaptobutyrate), pentaerythritol tris(4-mercaptobutyrate), ethylene glycol bis(mercaptoacetate), ethylene glycol bis(3-mercaptopropionate), ethylene glycol bis(3-mercaptobutyrate), ethylene glycol bis(4-mercaptobutyrate), trimethylolethane tris(mercaptoacetate), trimethylolethane tris(3-mercaptopropionate), trimethylolethane tris(3-mercaptobutyrate), trimethylolethane tris(4-mercaptobutyrate), trimethylolpropane tris(mercaptoacetate), trimethylolpropane tris(3-mercaptopropionate), trimethylolpropane tris(4-mercaptobutyrate), and the like.

[0026] Component (B2) is preferably at least one selected from the group consisting of 3,6-dioxa-1,8-octanedithiol, 1,4-bis(3-mercaptobutyryloxy)butane, and trimethylolpropane tris(3-mercaptobutyrate), and more preferably 3,6-dioxa-1,8-octanedithiol, 1,4-bis(3-mercaptobutyryloxy)butane, or trimethylolpropane tris(3-mercaptobutyrate).

[0027] The curable resin composition of the present invention is preferably capable of being rapidly cured even at a relatively low heating temperature (for example, 60° C.) From this viewpoint, the component (B2) is more preferably 3,6-dioxa-1,8-octanedithiol.

[0028] The amounts of component (B1) and component (B2) used are determined based on the molar ratio of epoxy groups to mercapto groups in the curable resin composition (i.e., the molar ratio of epoxy groups in component (A) to (the sum of mercapto groups in component (B1) and mercapto groups in component (B2))). In one embodiment of the present invention, from the viewpoint of curability, the molar ratio of epoxy groups to mercapto groups is preferably 0.2 or more, more preferably 0.6 or more, even more preferably 0.7 or more, particularly preferably 0.8 or more, and most preferably 0.9 or more, and is preferably 2.0 or less, more preferably 1.2 or less, even more preferably 1.1 or less, and particularly preferably 1.0 or less. In another embodiment of the present invention, from the viewpoint of curability, the molar ratio of epoxy groups to mercapto groups is preferably 0.2 to 2.0, more preferably 0.6 to 1.2, and even more preferably 0.7 to 1.0.

[0029] The molar ratio of mercapto groups in component (B2) to mercapto groups in component (B1) is preferably 30 / 70 to 70 / 30 (i.e., 0.43 to 2.33), more preferably 40 / 60 to 60 / 40 (i.e., 0.67 to 1.50), from the viewpoint of achieving both a low elastic modulus and high adhesion to metals in the resulting cured product.

[0030] <(C) BET specific surface area is 5 m ２ / g or more> The present invention provides calcium carbonate having a BET specific surface area of ​​5 m ２ The present invention is characterized by the use of calcium carbonate having a modulus of elasticity of 1 / g or more. By using component (C), it is possible to form a cured product having a low modulus of elasticity and high elongation. As component (C), for example, commercially available calcium carbonate available from Shiraishi Kogyosho Co., Ltd. can be used.

[0031] The BET specific surface area of ​​component (C) is preferably 6 m from the viewpoint of the viscosity of the curable resin composition. ２ / g or more, more preferably 7m ２ / g or more, more preferably 8m ２ / g or more, particularly preferably 8m ２ / g or more, preferably 50m ２ / g or less, more preferably 40m ２ / g or less, more preferably 35m ２ / g or less, particularly preferably 30m ２ / g or less. The BET specific surface area of ​​component (C) can be measured in accordance with JIS Z 8830. The BET specific surface area of ​​component (C) can also be measured using a known automatic specific surface area measuring device (for example, "Macsorb HM-1210" manufactured by Mountech Co., Ltd.).

[0032] From the viewpoint of the viscosity of the curable resin composition, the content of component (C) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, relative to 100 parts by mass of component (A); and is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, even more preferably 70 parts by mass or less, particularly preferably 50 parts by mass or less, and most preferably 40 parts by mass or less.

[0033] From the viewpoint of the properties of the resulting cured product, the mass ratio of component (C) / component (B1) in the curable resin composition is preferably 30 / 70 to 60 / 40 (i.e., 0.43 to 1.50), more preferably 30 / 70 to 55 / 45 (i.e., 0.43 to 1.22), and even more preferably 30 / 70 to 50 / 40 (i.e., 0.43 to 1.25). When two or more types of component (B1) are used, "component (B1)" in the "mass ratio of component (C) / component (B1)" means "the total of two or more types of component (B1)." When two or more types of component (C) are used, "component (C)" in the "mass ratio of component (C) / component (B1)" means "the total of two or more types of component (C)." Other expressions similar to "mass ratio of component (C) / component (B1)" also have the same meaning as "mass ratio of component (C) / component (B1)."

[0034] The mass ratio of component (C) / (component (B1)+component (B2)) in the curable resin composition is preferably 15 / 85 to 38 / 62 (i.e., 0.18 to 0.61), more preferably 18 / 82 to 35 / 65 (i.e., 0.22 to 0.54), and even more preferably 20 / 80 to 32 / 68 (i.e., 0.25 to 0.47), from the viewpoints of the viscosity of the curable resin composition and the properties of the resulting cured product.

[0035] <(D) BET specific surface area is 30 m ２ / g or more> The curable resin composition of the present invention contains, as component (D), silica particles having a BET specific surface area of ​​30 m or more in order to prevent precipitation of the powder component (C) in the curable resin composition. ２ / g or more. As component (D), commercially available silica particles available from, for example, Nippon Aerosil Co., Ltd., Admatechs Co., Ltd., etc. may be used. Component (D) may be used alone or in combination of two or more types.

[0036] Silica is generally classified as silica fine particles, fumed silica, silica aerogel, or silica glass. In this specification, "silica particles" refers to silica fine particles or fumed silica that are in particulate form.

[0037] The BET specific surface area of ​​component (D) is preferably 10 m from the viewpoint of preventing precipitation of component (C), which is a powder, in the curable resin composition. ２ / g or more, more preferably 30m ２ / g or more, more preferably 50m ２ / g or more, particularly preferably 70m ２ / g or more, most preferably 100m ２ / g or more, preferably 500m ２ / g or less, more preferably 400m ２ / g or less, more preferably 350m ２ / g or less. The BET specific surface area of ​​component (D) can be measured in accordance with JIS Z 8830. The BET specific surface area of ​​component (D) can also be measured using a known automatic specific surface area measuring device (for example, "Macsorb HM-1210" manufactured by Mountech Co., Ltd.).

[0038] When component (D) is used, the content thereof is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of component (A), from the viewpoint of preventing precipitation of powdery component (C) in the curable resin composition, and is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and even more preferably 16 parts by mass or less.

[0039] When component (D) is used, the mass ratio of component (D) / component (B1) in the curable resin composition is preferably 10 / 90 to 30 / 70 (i.e., 0.11 to 0.43), more preferably 10 / 90 to 27 / 73 (i.e., 0.11 to 0.37), and even more preferably 10 / 90 to 25 / 75 (i.e., 0.11 to 0.33), from the viewpoint of preventing precipitation of component (C), which is a powder, in the curable resin composition.

[0040] When component (D) is used, the mass ratio of component (D) / (component (B1)+component (B2)) in the curable resin composition is preferably 5 / 95 to 20 / 80 (i.e., 0.053 to 0.25), more preferably 6 / 94 to 15 / 85 (i.e., 0.064 to 0.18), and even more preferably 7 / 93 to 12 / 88 (i.e., 0.075 to 0.14), from the viewpoint of the effect of component (D) (i.e., preventing precipitation of powdery component (C) in the curable resin composition).

[0041] When component (D) is used, the mass ratio of component (D) / component (C) in the curable resin composition is, from the viewpoint of the viscosity of the curable resin composition, preferably 1 / 99 to 76 / 24 (i.e., 0.010 to 3.17), more preferably 2 / 98 to 63 / 37 (i.e., 0.020 to 1.70), even more preferably 3 / 97 to 50 / 50 (i.e., 0.031 to 1.00), and particularly preferably 10 / 90 to 30 / 70 (i.e., 0.111 to 0.428).

[0042] <(E) Curing Accelerator> The curable resin composition of the present invention may contain a curing accelerator as component (E) to accelerate the curing reaction between component (A) and components (B1) and (B2). As component (E), commercially available curing accelerators available from Ajinomoto Fine-Techno Co., Ltd., ACS Corporation, Asahi Kasei Corporation, T&K Toka Corporation, ADEKA Corporation, etc. may be used. Only one type of component (E) may be used, or two or more types may be used in combination.

[0043] The curing accelerator is preferably a solid-dispersion-type latent curing accelerator. In this specification, the term "solid-dispersion-type latent curing accelerator" refers to a compound that is insoluble in the curable resin composition at room temperature (25°C) and becomes solubilized by heating to accelerate the curing reaction.

[0044] Examples of the solid-dispersion type latent curing accelerator include imidazole compounds that are solid at room temperature (25° C.), solid-dispersion type amine adduct type latent curing accelerators, etc. Among these, solid-dispersion type amine adduct type latent curing accelerators are preferred.

[0045] Examples of imidazole compounds that are solid at room temperature include 2-heptadecylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-undecylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4-benzyl-5-hydroxymethylimidazole, 2,4-diamino-6-(2-methylimidazolyl-(1))-ethyl-S-triazine, 2,4-diamino-6-(2' 1-methylimidazolyl-(1'))-ethyl-S-triazine isocyanuric acid adduct, 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole-trimellitate, 1-cyanoethyl-2-phenylimidazole-trimellitate, N-(2-methylimidazolyl-1-ethyl)-urea, and the like.

[0046] Examples of the solid-dispersed amine adduct latent curing accelerator include a reaction product of an amine compound and an epoxy compound (hereinafter, may be referred to as a "solid-dispersed amine-epoxy adduct latent curing accelerator"), and a reaction product of an amine compound and an isocyanate compound or a urea compound (hereinafter, may be referred to as a "solid-dispersed urea adduct latent curing accelerator").

[0047] Examples of amine compounds that are raw materials for solid-dispersion type amine adduct latent curing accelerators include aliphatic amines such as diethylenetriamine, triethylenetetramine, n-propylamine, 2-hydroxyethylaminopropylamine, cyclohexylamine, and 4,4'-diamino-dicyclohexylmethane; aromatic amines such as 4,4'-diaminodiphenylmethane and 2-methylaniline; and nitrogen-containing heterocyclic compounds such as imidazole compounds (e.g., 2-ethyl-4-methylimidazole), 2-ethyl-4-methylimidazoline, 2,4-dimethylimidazoline, piperidine, and piperazine.

[0048] The amine compound is preferably a compound having one or more active hydrogen atoms capable of addition reacting with an epoxy group and at least one functional group selected from the group consisting of a tertiary amino group and a pyridyl group, and by using such a compound, a latent curing accelerator having excellent curing acceleration ability can be obtained. Examples of such compounds include the following: amine compounds such as dimethylaminopropylamine, diethylaminopropylamine, di-n-propylaminopropylamine, dibutylaminopropylamine, dimethylaminoethylamine, diethylaminoethylamine, and N-methylpiperazine; imidazole compounds such as 2-methylimidazole, 2-ethylimidal, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 1-(2-hydroxy-3-phenoxypropyl)-2-methylimidazole, 1-(2-hydroxy-3-phenoxypropyl)-2-ethyl-4-methylimidazole, 1-(2-hydroxy-3-butoxypropyl)-2-methylimidazole, 1-(2-hydroxy-3-butoxypropyl)-2-ethyl-4-methylimidazole, 2-benzimidazole, and 2-mercaptobenzimidazole; 2-Dimethylaminoethanol, 1-methyl-2-dimethylaminoethanol, 1-phenoxymethyl-2-dimethylaminoethanol, 2-diethylaminoethanol, 1-butoxymethyl-2-dimethylaminoethanol, 1-(2-hydroxy-3-phenoxypropyl)-2-phenylimidazoline, 1-(2-hydroxy-3-butoxypropyl)-2-methylimidazoline, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol, N-β-hydroxyethylmorpho phosphorus, 2-dimethylaminoethanethiol, 2-mercaptopyridine, 2-mercaptobenzothiazole, 4-mercaptopyridine, N,N-dimethylaminobenzoic acid, N,N-dimethylglycine, nicotinic acid, isonicotinic acid, picolinic acid, alcohol compounds having a tertiary amino group or a pyridyl group, such as N,N-dimethylglycine hydrazide, N,N-dimethylpropionic acid hydrazide, nicotinic acid hydrazide, and isonicotinic acid hydrazide, phenol compounds, thiol compounds, carboxylic acid compounds, and hydrazide compounds.

[0049] When producing a solid-dispersion type amine-epoxy adduct latent curing accelerator, in addition to the amine compound and the epoxy compound, a compound having two or more active hydrogen atoms may be used. Examples of such compounds include polyhydric phenols such as bisphenol A, bisphenol F, bisphenol S, hydroquinone, catechol, resorcinol, pyrogallol, and phenol novolac resin, polyhydric alcohols such as trimethylolpropane, polycarboxylic acids such as adipic acid and phthalic acid, 1,2-dimercaptoethane, 2-mercaptoethanol, 1-mercapto-3-phenoxy-2-propanol, mercaptoacetic acid, anthranilic acid, and lactic acid.

[0050] Examples of epoxy compounds that are raw materials for solid-dispersion type amine-epoxy adduct latent curing accelerators include the following: polyglycidyl ethers obtained by reacting polyhydric alcohols such as bisphenol A, bisphenol F, catechol, resorcinol, glycerin, and polyethylene glycol with epichlorohydrin; glycidyl ether esters obtained by reacting hydroxy acids such as p-hydroxybenzoic acid and β-hydroxynaphthoic acid with epichlorohydrin; polyglycidyl esters obtained by reacting polycarboxylic acids such as phthalic acid and terephthalic acid with epichlorohydrin; glycidyl amine compounds obtained by reacting 4,4'-diaminodiphenylmethane, m-aminophenol, or the like with epichlorohydrin; polyfunctional epoxy compounds such as epoxidized phenol novolac resins, epoxidized cresol novolac resins, and epoxidized polyolefins; and monofunctional epoxy compounds such as butyl glycidyl ether, phenyl glycidyl ether, and glycidyl methacrylate.

[0051] Examples of isocyanate compounds that are raw materials for solid-dispersed urea adduct-based latent curing accelerators include the following: monofunctional isocyanate compounds such as n-butyl isocyanate, isopropyl isocyanate, phenyl isocyanate, and benzyl isocyanate; polyfunctional isocyanate compounds such as hexamethylene diisocyanate, tolylene diisocyanate (e.g., 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate), 1,5-naphthalene diisocyanate, diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, xylylene diisocyanate, paraphenylene diisocyanate, 1,3,6-hexamethylene triisocyanate, and bicycloheptane triisocyanate; terminal isocyanate group-containing compounds obtained by reacting a polyfunctional isocyanate compound with a compound containing an active hydrogen atom.

[0052] Examples of the terminal isocyanate group-containing compound include a compound obtained by reacting tolylene diisocyanate with trimethylolpropane, and a compound obtained by reacting tolylene diisocyanate with pentaerythritol.

[0053] Examples of urea compounds that are raw materials for solid dispersion type urea adduct latent curing accelerators include urea and thiourea.

[0054] The solid-dispersion type amine adduct latent curing accelerator can be produced, for example, by appropriately mixing the raw materials, reacting them at a temperature of room temperature to 200° C., cooling to solidify, and pulverizing the resulting solid. Alternatively, the solid-dispersion type amine adduct latent curing accelerator can be produced, for example, by reacting the raw materials in a solvent such as methyl ethyl ketone, dioxane, or tetrahydrofuran, removing the solvent, and then pulverizing the resulting solid.

[0055] When component (E) is used, the content thereof is preferably at least 0.1 parts by mass, more preferably at least 1 part by mass, and even more preferably at least 5 parts by mass, and is preferably at most 30 parts by mass, more preferably at most 25 parts by mass, and even more preferably at most 20 parts by mass, per 100 parts by mass of component (A), from the viewpoint of accelerating the curing reaction between component (A) and components (B1) and (B2).

[0056] <(F) Storage stabilizer> The curable resin composition of the present invention may contain a storage stabilizer as component (F) in order to improve its storage stability. As component (F), for example, a commercially available storage stabilizer available from Tokyo Chemical Industry Co., Ltd., etc. may be used. Only one type of component (F) may be used, or two or more types may be used in combination.

[0057] Examples of the storage stabilizer include borate compounds, titanate compounds, aluminate compounds, and zirconate compounds.

[0058] Examples of the borate compound include trimethyl borate, triethyl borate, tri-n-propyl borate, triisopropyl borate, tri-n-butyl borate, tripentyl borate, triallyl borate, trihexyl borate, tricyclohexyl borate, trioctyl borate, trinonyl borate, tridecyl borate, tridodecyl borate, trihexadecyl borate, trioctadecyl borate, tris(2-ethylhexyloxy)borane, tribenzyl borate, triphenyl borate, tri-o-tolyl borate, tri-m-tolyl borate, and triethanolamine borate.

[0059] Examples of titanate compounds include tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, and tetraoctyl titanate.

[0060] Examples of the aluminate compound include triethyl aluminate, tripropyl aluminate, triisopropyl aluminate, tributyl aluminate, and trioctyl aluminate.

[0061] Examples of the zirconate compound include tetraethyl zirconate, tetrapropyl zirconate, tetraisopropyl zirconate, and tetrabutyl zirconate.

[0062] As component (F), from the viewpoints of versatility and safety, borate compounds are preferred, with triethyl borate, tri-n-propyl borate, triisopropyl borate, and tri-n-butyl borate being more preferred, and triethyl borate being even more preferred.

[0063] When component (F) is used, from the viewpoint of storage stability, the content thereof is preferably 0.001 part by mass or more, more preferably 0.05 part by mass or more, even more preferably 0.1 part by mass or more, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, relative to 100 parts by mass of component (A).

[0064] <Other Components> The curable resin composition of the present invention may contain other components different from the above-described components, as long as the effects of the present invention are not impaired. Examples of other components include a silane coupling agent, a thermoplastic resin, and a reactive diluent.

[0065] <Best Mode> In a best mode, the curable resin composition of the present invention comprises the following components (A) to (F): (A) a bisphenol A-type liquid epoxy resin, (B1) tris(3-mercaptopropyl)isocyanurate, (B2) 3,6-dioxa-1,8-octanedithiol, (C) a bisphenol A-type liquid epoxy resin having a BET specific surface area of ​​8 to 30 m ２ / g, (D) calcium carbonate having a BET specific surface area of ​​100 to 350 m ２ / g of silica particles, (E) a solid-dispersion-type latent curing accelerator which is a reaction product of an amine compound and an epoxy compound, and (F) a storage stabilizer which is a borate compound, wherein the content of component (A) is 40 to 65 mass% relative to the entire curable resin composition, the molar ratio of epoxy groups in component (A) to (the sum of mercapto groups in component (B1) and mercapto groups in component (B2)) is 0.8 to 1.1, the molar ratio of mercapto groups in component (B2) to mercapto groups in component (B1) is 40 / 60 to 60 / 40, the content of component (C) is 10 to 40 parts by mass relative to 100 parts by mass of component (A), and the content of component (D) is 3 to 16 parts by mass relative to 100 parts by mass of component (A), The content of component (E) is 5 to 20 parts by mass per 100 parts by mass of component (A), and the content of component (F) is 0.1 to 3 parts by mass per 100 parts by mass of component (A).

[0066] In the best mode described above, the epoxy equivalent of component (A) (ie, bisphenol A type liquid epoxy resin) is preferably 100 to 500 g / eq.

[0067] In the best mode described above, the mass ratio of component (C) / component (B1) is preferably 30 / 70 to 50 / 40.

[0068] In the best mode described above, the mass ratio of component (C) / (component (B1)+component (B2)) is preferably 20 / 80 to 32 / 68.

[0069] In the best mode described above, the mass ratio of component (D) / component (B1) is preferably 10 / 90 to 25 / 75.

[0070] In the best mode described above, the mass ratio of component (D) / (component (B1)+component (B2)) is preferably 7 / 93 to 12 / 88.

[0071] In the best mode described above, the mass ratio of component (D) / component (C) is preferably 10 / 90 to 30 / 70.

[0072] In the best mode described above, component (F) is preferably at least one selected from the group consisting of triethyl borate, tri-n-propyl borate, triisopropyl borate, and tri-n-butyl borate, and more preferably triethyl borate.

[0073] <Viscosity of Curable Resin Composition> The viscosity of the curable resin composition of the present invention at 25°C is preferably 0.5 to 50 Pa·s, more preferably 0.7 to 30 Pa·s, and even more preferably 1.0 to 20 Pa·s. The viscosity of the curable resin composition at 25°C is a value measured by maintaining the temperature of the curable resin composition at 25°C (±0.2°C) using an E-type viscometer (for example, "RE-85U" manufactured by Toki Sangyo Co., Ltd.) and a 3°×R14 rotor, with a measurement sample of 0.4 ml and a rotation speed of 20 rpm.

[0074] <Production and curing of curable resin composition> The curable resin composition of the present invention is preferably a one-component curable resin composition. The one-component curable resin composition can be produced, for example, by uniformly mixing the components using a known mixing device.

[0075] The curable resin composition of the present invention can be cured by heating. The heating temperature is preferably 60 to 150°C, more preferably 70 to 150°C, and even more preferably 75 to 120°C, and the heating time is preferably 10 to 120 minutes, and more preferably 10 to 90 minutes.

[0076] The modulus of elasticity of a 100 μm thick cured product obtained by curing the curable resin composition of the present invention at 80° C. for 60 minutes is preferably 2000 MPa or less, more preferably 1500 MPa or less.

[0077] <Adhesive> The curable resin composition of the present invention, which can form a cured product having a low elastic modulus, high adhesion to metal, and high elongation, is useful as an adhesive (particularly, a liquid adhesive). Therefore, the present invention also provides an adhesive (particularly, a liquid adhesive) containing the curable resin composition of the present invention. The adhesive is preferably used for bonding components of a camera module.

[0078] The viscosity of the adhesive of the present invention at 25°C is preferably 0.5 to 50 Pa·s, more preferably 0.7 to 30 Pa·s, and even more preferably 1.0 to 20 Pa·s. The viscosity of the adhesive at 25°C is a value measured by maintaining the temperature of the adhesive at 25°C (±0.2°C) using an E-type viscometer (for example, the "RE-85U" manufactured by Toki Sangyo Co., Ltd.) and a 3°×R14 rotor, with a measurement sample of 0.4 ml and a rotation speed of 20 rpm.

[0079] The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples.

[0080] [Preparation of Curable Resin Compositions] The components were mixed in the amounts shown in Tables 1 to 3 to prepare the curable resin compositions of Examples 1 to 10 and Comparative Examples 1 to 4. The numerical values ​​of each component shown in Tables 1 to 3 indicate the blend amount, and the unit is "parts by mass."

[0081] The "equivalent weight" in Tables 1 to 3 means "epoxy equivalent weight" for component (A), and "mercapto equivalent weight" for components (B1), (B2), and (B').

[0082] As shown in Tables 1 to 3, in the examples and comparative examples, the molar ratio of epoxy groups to mercapto groups in the curable resin compositions was approximately 1.0.

[0083] Specifically, the epoxy resin (component (A)) and curing agent were weighed out into dedicated plastic containers in the amounts shown in Tables 1 to 3. As the curing agent, component (B1) and component (B2) were used in Examples 1 to 8 and Comparative Example 2, component (B1) was used in Comparative Example 1, component (B1) and component (B') were used in Comparative Example 3, and component (B2) was used in Comparative Example 4.

[0084] Thereafter, using a planetary centrifugal mixer, Awatori Rentaro (Thinky Corporation; ARE-310), the mixture was thoroughly mixed at 2000 rpm for approximately 30 seconds to 1 minute at room temperature of 25°C, to obtain a liquid mixture. Calcium carbonate (component (C) or component (C')), silica particles (component (D)), a curing accelerator (component (E)), and a storage stabilizer (component (F)) were added to the liquid mixture, and the mixture was thoroughly mixed at 2000 rpm for approximately 30 seconds to 1 minute at room temperature of 25°C using a planetary centrifugal mixer. Finally, the mixture was degassed under vacuum (set to pressure 0) at 900 rpm for 2 minutes using a Kyoritsu Seiki Co., Ltd. automatic planetary centrifugal mixer / defoamer HM-200W, to obtain a curable resin composition. The components used were as follows:

[0085] [Component (A): Epoxy resin] YL-980 (manufactured by Mitsubishi Chemical Corporation, bisphenol A type liquid epoxy resin, epoxy equivalent: 186 g / eq) ZX-1059 (manufactured by Nippon Steel Chemical & Material Co., Ltd., bisphenol A type liquid epoxy resin + bisphenol F type liquid epoxy resin, epoxy equivalent: 165 g / eq) EXA-4850-150 (manufactured by DIC Corporation, modified bisphenol A type liquid epoxy resin, epoxy equivalent: 450 g / eq)

[0086] [Component (B1): Compound having a cyclic structure and three or four mercapto groups] TMPIC (manufactured by Ajinomoto Fine-Techno Co., Inc., tris(3-mercaptopropyl)isocyanurate, number of mercapto groups per molecule: 3, mercapto equivalent: 117 g / eq) C3TS-G (manufactured by Shikoku Chemicals Corporation, tetrahydro-1,3,4,6-tetrakis(3-mercaptopropyl)-imidazo[4,5-d]imidazole-2,5(1H,3H)-dione, number of mercapto groups per molecule: 4, mercapto equivalent: 110 g / eq)

[0087] [Component (B2): Compound having no cyclic structure and having two or three mercapto groups] 3,6-dioxa-1,8-octanedithiol (manufactured by Tokyo Chemical Industry Co., Ltd., number of mercapto groups per molecule: 2, mercapto equivalent: 91 g / eq) BD-1 (manufactured by Resonaq, 1,4-bis(3-mercaptobutyryloxy)butane, number of mercapto groups per molecule: 2, mercapto equivalent: 147 g / eq) TPMB (manufactured by Resonaq, trimethylolpropane tris(3-mercaptobutyrate), number of mercapto groups per molecule: 3, mercapto equivalent: 147 g / eq)

[0088] [Component (B'): a curing agent that does not fall under either component (B1) or component (B2)] 1-thioglycerol (manufactured by Tokyo Chemical Industry Co., Ltd., number of mercapto groups per molecule: 1, mercapto equivalent: 108 g / eq)

[0089] [Component (C): BET specific surface area of ​​5 m ２ / g or more] Vigot-10 (Shiraishi Kogyo Co., Ltd., calcium carbonate (CaCO ３ ), BET specific surface area: 13.5m ２ / g) Shiratsuyuuka CC-R (Shiraishi Kogyo Co., Ltd., calcium carbonate (CaCO ３ ), BET specific surface area: 18.0m ２ / g)

[0090] [Component (C'): BET specific surface area of ​​5 m ２ / g or less] W-B (Shiraishi Kogyo Co., Ltd., calcium carbonate (CaCO ３ ), BET specific surface area: 0.6m ２ / g)

[0091] [Component (D): BET specific surface area of ​​30 m ２ / g or more] A200 (manufactured by Nippon Aerosil Co., Ltd., fumed silica, BET specific surface area: 200 m ２ / g)

[0092] [Component (E): Curing Accelerator] PN-F (manufactured by Ajinomoto Fine-Techno Co., Inc., solid dispersion type amine-epoxy adduct latent curing accelerator)

[0093] [Component (F): Storage Stabilizer] TEB (triethyl borate, manufactured by Tokyo Chemical Industry Co., Ltd.)

[0094] [Measurement of viscosity of curable resin composition at 25°C] The temperature of the curable resin compositions obtained in the examples and comparative examples was kept at 25°C (±0.2°C), and the viscosity (Pa s) at 25°C was measured using an E-type viscometer ("RE-85U" manufactured by Toki Sangyo Co., Ltd.) and a 3°×R14 rotor at a rotation speed of 20 rpm and a measurement sample of 0.4 ml. The results are shown in Tables 1 to 3. Note that the viscosity of the curable resin composition of Comparative Example 3 increased significantly after mixing the raw materials, making it impossible to measure its viscosity.

[0095] [Evaluation of Elastic Modulus and Elongation at Break] The curable resin compositions obtained in the Examples and Comparative Examples were applied to a release PET film (NS-80A, manufactured by Toray Industries, Inc.) using a bar coater and heated at 80°C for 60 minutes to obtain a cured product. The resulting 100 μm-thick cured product was punched out using a Dumbbell Super Dumbbell Cutter (Model: SDMK-5889-01) to prepare a test specimen. The release PET film was peeled off from the test specimen. A tensile test was performed using a universal testing machine (Shimadzu Corporation's AGS-5kNX) at a temperature of 25°C, a relative humidity of 50%, and a tensile speed of 5 mm / min to measure the elastic modulus (MPa) and elongation at break (%). The elastic modulus and elongation at break were evaluated according to the following criteria. The results are shown in Tables 1 to 3 below. The curable resin composition of Comparative Example 3 could not be evaluated due to significant viscosity increase after mixing the raw materials. <Evaluation criteria for elastic modulus> ○ (Good): Elastic modulus 1500 MPa or less △ (Acceptable): Elastic modulus greater than 1500 MPa and less than 2000 MPa × (Poor): Elastic modulus greater than 2000 MPa <Evaluation criteria for elongation at break> ○ (Good): 40% or more △ (Acceptable): 20% or more and less than 40% × (Poor): Less than 20%

[0096] [Evaluation of Adhesion to Mild Steel Plate] Two test pieces of mild steel plate (JIS G3141, hereinafter referred to as "SPCC") were prepared, and oil was wiped off with a cloth moistened with acetone. Then, the adhesive surface of the SPCC was polished with an endless belt #120. The curable resin composition was uniformly applied to the polished surface of the SPCC to a thickness of approximately 1 mm. The two test pieces were attached and clamped with two clips so that the coated surfaces overlapped by approximately 12 mm. Any exuded curable resin composition was immediately wiped off with a cloth. The test pieces were evenly arranged in an oven and heated to 80°C for 60 minutes for curing and adhesion. Three test pieces were prepared for each curable resin composition. Using the obtained test specimens, a tensile test was carried out in accordance with JIS K 6850 using a Tensilon universal testing machine (manufactured by TSE Corporation, AC-50KN-CM) (measurement conditions: temperature 25°C, relative humidity 60%, tensile speed 5 mm / min). The maximum load (N) at which the test specimen broke and the measured adhesive area (mm 2 ) and calculated using the following formula: Tensile shear adhesive strength 1 (N / mm 2 )=Maximum load (N) / Adhesive area (mm 2 ) and evaluated the adhesion to SPCC according to the following criteria. The results are shown in Tables 1 to 3 below. Note that the curable resin composition of Comparative Example 3 could not be evaluated because the viscosity of the curable resin composition increased significantly after mixing the raw materials. <Evaluation criteria for adhesion to SPCC> ○ (Good): Tensile shear adhesive strength 1 is 15.0 N / mm ２ Above △ (Acceptable): Tensile shear adhesive strength 1 is 10.0 N / mm ２ 15.0N / mm or more ２ Less than × (bad): Tensile shear adhesive strength 1 is 10.0 N / mm ２ less than

[0097] [Evaluation of fast curing properties] Test specimens were prepared using the same procedure as in "Evaluation of adhesion to mild steel plate," and were thermally cured at 80°C for 10 minutes to adhere. Three test specimens were prepared for each curable resin composition. Using the obtained test specimens, a tensile test was carried out in accordance with JIS K 6850 using a Tensilon universal testing machine (manufactured by TSE Corporation, AC-50KN-CM) (measurement conditions: temperature 25°C, relative humidity 60%, tensile speed 5 mm / min). The maximum load (N) at which the test specimen broke and the measured adhesive area (mm 2 ) and calculated using the following formula: Tensile shear adhesive strength 2 (N / mm 2 )=Maximum load (N) / Adhesive area (mm 2 ) The tensile shear adhesive strength 2 was calculated by the above formula.

[0098] Furthermore, the following formula is used: Strength ratio (%) = 100 × tensile shear adhesive strength 2 (N / mm 2 ) / Tensile shear adhesive strength 1 (N / mm 2 ) and evaluated the rapid curing property according to the following criteria. The results are shown in Tables 1 to 3 below. Note that the curable resin composition of Comparative Example 3 could not be evaluated because the viscosity of the curable resin composition increased significantly after mixing the raw materials. ○ (Good): Strength ratio was 80% or more △ (Fair): Strength ratio was 60% or more but less than 80% × (Poor): Strength ratio was less than 60%

[0099]

[0100]

[0101]

[0102] The curable resin composition of the present invention can form a cured product having a low modulus of elasticity, high adhesion to metals, and high elongation, and is useful as an adhesive.

[0103] This application is based on Japanese Patent Application No. 2024-145676, the contents of which are incorporated in their entirety herein.

Claims

1. The following components (A) to (C): (A) an epoxy resin, (B1) a compound having a cyclic structure and three or four mercapto groups, (B2) a compound having no cyclic structure and two or three mercapto groups, and (C) a compound having a BET specific surface area of ​​5 m ２ / g or more of calcium carbonate.

2. Furthermore, the following component (D): (D) BET specific surface area is 30 m ２ The curable resin composition according to claim 1, comprising silica particles having a surface area of ​​1 / g or more.

3. The curable resin composition according to claim 1 or 2, wherein the molar ratio of mercapto groups in component (B2) to mercapto groups in component (B1) is 30 / 70 to 70 / 30.

4. The curable resin composition according to claim 1 or 2, wherein the mass ratio of component (C) / component (B1) is 30 / 70 to 60 / 40.

5. The curable resin composition according to claim 2, wherein the mass ratio of component (D) / component (B1) is 10 / 90 to 30 / 70.

6. The curable resin composition according to claim 1 or 2, wherein component (B2) has an ether bond and does not have an ester bond.

7. The curable resin composition according to claim 1 or 2, wherein the modulus of elasticity of a cured product having a thickness of 100 μm obtained by curing the curable resin composition at 80° C. for 60 minutes is 2000 MPa or less.

8. The curable resin composition according to claim 1 or 2, wherein the number of mercapto groups in component (B2) is 2.

9. An adhesive comprising the curable resin composition according to claim 1 or 2.

10. The adhesive of claim 9, which is for bonding between components of a camera module.

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