Conductive resin adhesive agent and cured product of same

Abstract

Provided is a conductive resin adhesive agent which can be cured in a short period of time and from which a cured product having excellent adhesive strength and excellent conductivity is obtained. This conductive resin adhesive agent contains the following components (A)-(D). Component (A): An epoxy resin having two or more glycidyl groups. Component (B): A polyfunctional vinyl ether having a ring structure (excluding the epoxy resin having two or more glycidyl groups). Component (C): Conductive particles. Component (D): A thermal cationic polymerization initiator.

Description

Conductive resin adhesive and its cured product

[0001] The present invention relates to a conductive resin adhesive that can be cured in a short time to give a cured product that has excellent adhesive strength and electrical conductivity, and to the cured product thereof.

[0002] Conventionally, conductive resin adhesives have been used for applications such as fixing and grounding electrical and electronic components in smartphones, electronic mobile devices, etc. In recent years, plastics have become widely used as components for electronic components in order to reduce their size and weight. Therefore, the use of adhesives that require long periods of heating has been difficult, as excessive heating can cause deformation of the components. Therefore, a conductive resin adhesive using cationic polymerization, as disclosed in JP 2015-160861 A, is known as a fast-curing conductive resin adhesive with a short curing time.

[0003] However, fast-curing conductive resin adhesives have the problem of easily causing unevenness in the cured product, resulting in reduced adhesive strength and / or poor electrical conductivity of the cured product. Therefore, one object of the present invention is to provide a conductive resin adhesive that can be cured in a short time and that has excellent adhesive strength and electrical conductivity of the cured product. Another object of the present invention is to provide a cured product of the conductive resin adhesive.

[0004] As a result of extensive research to achieve the above object, the inventors discovered a method for producing a conductive resin adhesive that can be cured in a short time and that has excellent adhesive strength and electrical conductivity after curing, and thus completed the present invention.

[0005] The gist of the present invention will be described below. One aspect of the present invention, which can achieve at least one of the above-mentioned objects, relates to: [1] a conductive resin adhesive comprising the following components (A) to (D): component (A): an epoxy resin having two or more glycidyl groups, component (B): a polyfunctional vinyl ether having a cyclic structure (excluding epoxy resins having two or more glycidyl groups), component (C): conductive particles, and component (D): a thermal cationic polymerization initiator.

[0006] The present invention also encompasses the following embodiments [2] to

[10] as non-limiting examples of preferred embodiments: [2] The conductive resin adhesive according to [1], wherein the component (A) comprises a bisphenol epoxy resin; [3] The conductive resin adhesive according to [1] or [2], wherein the component (A) comprises a hydrogenated bisphenol epoxy resin; [4] The conductive resin adhesive according to any one of [1] to [3], wherein the component (B) is a polyfunctional vinyl ether having an alicyclic structure; [5] The conductive resin adhesive according to any one of [1] to [4], wherein the component (C) comprises crystalline conductive particles; [6] The conductive resin adhesive according to any one of [1] to [5], wherein the cation species of the component (D) is a quaternary ammonium cation; [7] The conductive resin adhesive according to any one of [1] to [6], wherein the component (B) is cyclohexanedimethanol divinyl ether; [8] The conductive resin adhesive according to any one of [1] to [7], wherein the electrical conductivity of a cured product cured at 130°C for 3 minutes (a cured product cured by heating at 130°C for 3 minutes; a cured product obtained by heating at 130°C for 3 minutes) is 0.3 Ω or less.

[0007] Another aspect of the present invention, which can achieve at least one of the above objects, relates to a cured product obtained by curing the conductive resin adhesive described in any one of [9] [1] to [8] (a cured product obtained by curing the conductive resin adhesive described in any one of [1] to [8]).

[0008] However, the present invention is not limited to the above aspects or embodiments [1] to [9].

[0009] The present invention will be described in detail below. Note that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the claims. The embodiments described in this specification can be arbitrarily combined to form other embodiments.

[0010] In this specification, "X to Y" is used to mean "X or more and Y or less," with the numerical values ​​(X and Y) before and after it being included as the lower and upper limits. In this specification, the term "(meth)acrylic" means both acrylic and methacrylic. In this specification, the term "(meth)acrylate" means both acrylate and methacrylate. In this specification, unless otherwise specified, operations and measurements of physical properties, etc. are performed under conditions of 25°C and a relative humidity of 55% RH.

[0011] <Conductive Resin Adhesive> One aspect of the present invention relates to a conductive resin adhesive containing the following components (A) to (D): component (A): an epoxy resin having two or more glycidyl groups; component (B): a polyfunctional vinyl ether having a cyclic structure (excluding epoxy resins having two or more glycidyl groups); component (C): conductive particles; and component (D): a thermal cationic polymerization initiator.

[0012] According to this aspect, a conductive resin adhesive can be provided that can be cured in a short time and has excellent adhesive strength and conductivity in the cured product.

[0013] The state of the conductive resin adhesive according to an embodiment is not particularly limited. The conductive resin adhesive according to an embodiment may be a solid or a liquid at 25° C. It is preferable that the conductive resin adhesive be a liquid at 25° C., as this makes it easier to apply to an adherend and provides superior adhesive strength when cured.

[0014] In this specification, the term "liquid" refers to a liquid that is viscous at a shear rate of 10 s using a cone-plate type rotational viscometer under an environment of 25°C and 55% RH. －１ This indicates that the viscosity measured at 10000 Pa·s or less.

[0015] Hereinafter, each component constituting the conductive resin adhesive according to this embodiment will be described.

[0016] [Component (A)] Component (A) is an epoxy resin having two or more glycidyl groups. In this specification, an epoxy resin having two or more glycidyl groups refers to a compound having two or more glycidyl groups (i.e., a compound having two or more glycidyl groups in one molecule). Component (A) may be a solid or liquid at 25°C, and its state is not particularly limited, as long as it is a compound having two or more glycidyl groups (a compound having two or more glycidyl groups in one molecule). The description of the liquid is the same as above. From the viewpoint of excellent workability, component (A) is preferably a liquid at 25°C. Component (A) may be a combination of a solid epoxy resin having two or more glycidyl groups and a liquid epoxy resin having two or more glycidyl groups. Component (A) may be a commercially available product and / or a synthetic product. Component (A) may be used alone or in combination of two or more types.

[0017] In an epoxy resin having two or more glycidyl groups as component (A), the number of glycidyl groups (i.e., the number of glycidyl groups in one molecule) is not particularly limited as long as it is at least 2. In an epoxy resin having two or more glycidyl groups as component (A), the number of glycidyl groups is preferably 2 or more and 6 or less, more preferably 2 or more and 4 or less, and even more preferably 2.

[0018] The component (A) may be any resin having two or more glycidyl groups, and may be an aromatic epoxy resin, a heterocyclic epoxy resin, an alicyclic epoxy resin, an aliphatic epoxy resin, or the like, without any particular limitation on its type.

[0019] Examples of component (A) include aromatic epoxy resins such as bisphenol-type epoxy resins, novolac-type epoxy resins (e.g., phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, etc.), and naphthalene-type epoxy resins having four glycidyl groups; hydrogenated bisphenol-type epoxy resins; alkylene glycol-type epoxy resins; glycidyl amine compounds; etc. These may be used alone or in combination of two or more.

[0020] Component (A) preferably contains an aromatic epoxy resin and / or a hydrogenated bisphenol epoxy resin, more preferably a bisphenol epoxy and / or a hydrogenated bisphenol epoxy resin, and even more preferably a bisphenol epoxy and / or a hydrogenated bisphenol epoxy resin. That is, component (A) preferably contains at least one epoxy resin selected from the group consisting of aromatic epoxy resins and hydrogenated bisphenol epoxy resins, more preferably at least one epoxy resin selected from the group consisting of bisphenol epoxy and hydrogenated bisphenol epoxy resins, and even more preferably at least one epoxy resin selected from the group consisting of bisphenol epoxy and hydrogenated bisphenol epoxy resins. According to an embodiment of the conductive resin adhesive containing an aromatic epoxy resin, particularly a bisphenol epoxy resin, the cured product exhibits excellent electrical conductivity when cured in a short time. According to an embodiment of the conductive resin adhesive containing a hydrogenated bisphenol epoxy resin, the cured product exhibits excellent adhesive strength when cured in a short time. In one embodiment, component (A) preferably contains an aromatic epoxy resin, more preferably contains a bisphenol-type epoxy resin, even more preferably consists solely of a bisphenol-type epoxy resin, and particularly preferably consists solely of a difunctional bisphenol-type epoxy resin. In one embodiment, component (A) preferably contains a hydrogenated bisphenol-type epoxy resin, more preferably consists solely of a hydrogenated bisphenol-type epoxy resin, and even more preferably consists solely of a difunctional hydrogenated bisphenol-type epoxy resin. In one embodiment, component (A) preferably contains an aromatic epoxy resin and a hydrogenated bisphenol-type epoxy resin, more preferably contains a bisphenol-type epoxy resin and a hydrogenated bisphenol-type epoxy resin, even more preferably a bisphenol-type epoxy resin and a hydrogenated bisphenol-type epoxy resin, and particularly preferably a difunctional bisphenol-type epoxy resin and a difunctional hydrogenated bisphenol-type epoxy resin.

[0021] In one embodiment, the proportion by mass of the aromatic epoxy resin relative to the total mass of component (A) is not particularly limited, but may be 40 mass% or more, 50 mass% or more, 90 mass% or more, or even 100 mass%. When two or more aromatic epoxy resins are used in combination, the amount of aromatic epoxy resin represents the total amount of these.

[0022] In one embodiment, the proportion by mass of the bisphenol epoxy resin relative to the total mass of component (A) is not particularly limited, but may be 40% by mass or more, 50% by mass or more, 90% by mass or more, or even 100% by mass. When two or more bisphenol epoxy resins are used in combination, the amount of the bisphenol epoxy resin represents the total amount of these.

[0023] In one embodiment, the proportion by mass of the hydrogenated bisphenol epoxy resin relative to the total mass of component (A) is not particularly limited, but may be 40% by mass or more, 50% by mass or more, 90% by mass or more, or even 100% by mass. When two or more hydrogenated bisphenol epoxy resins are used in combination, the amount of hydrogenated bisphenol epoxy resin represents the total amount of these.

[0024] Common epoxy resins include alicyclic epoxy resins in addition to compounds having a glycidyl group. In this specification, an alicyclic epoxy resin refers to a compound having an alicyclic epoxy group, and an alicyclic epoxy group refers to a functional group having a cyclic structure in which an epoxy ring and a saturated hydrocarbon ring are condensed. Examples of alicyclic epoxy groups include, but are not limited to, a 3,4-epoxycyclohexyl group. In this specification, an epoxy resin having one or more alicyclic epoxy groups and two or more glycidyl groups is considered to be component (A). On the other hand, an epoxy resin having an alicyclic epoxy group but no glycidyl group, and an epoxy resin having an alicyclic epoxy group but only one glycidyl group, are not considered to be component (A). However, from the perspective of adhesive strength of the cured product, it is preferable that component (A) be composed solely of a compound having no alicyclic epoxy group but two or more glycidyl groups (an epoxy resin having no alicyclic epoxy group but two or more glycidyl groups).

[0025] In this specification, compounds generally used as silane coupling agents are treated as optional components described below. In this specification, the term "silane coupling agent" refers to a compound in which at least one hydrolyzable group (such as an alkoxy group or an aryloxy group) is bonded to a silicon atom and at least one organic functional group other than the hydrolyzable group is bonded to a silicon atom. In this specification, even if a glycidyl group-containing silane coupling agent has two or more glycidyl groups, the glycidyl group-containing silane coupling agent is not treated as component (A) but as a silane coupling agent. In this specification, even if a glycidyl group-containing silane coupling agent has two or more glycidyl groups, the glycidyl group-containing silane coupling agent is not treated as an epoxy resin having two or more glycidyl groups but as a silane coupling agent. It is preferable that the epoxy resin having two or more glycidyl groups as component (A) does not have a silicon atom (does not have a silicon atom in the molecule).

[0026] The bisphenol epoxy resin is not particularly limited as long as it is an epoxy resin having a bisphenol skeleton. Examples of the bisphenol epoxy resin include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, bisphenol AD ​​epoxy resin, urethane-modified bisphenol epoxy resin, rubber-modified bisphenol epoxy resin, and polyoxyalkylene-modified bisphenol epoxy resin. These may be used alone or in combination of two or more.

[0027] In view of achieving superior electrical conductivity of the cured product when cured in a short time, the bisphenol type epoxy resin preferably comprises at least one selected from the group consisting of bisphenol A type epoxy resins, bisphenol F type epoxy resins, and polyoxyalkylene-modified bisphenol type epoxy resins, more preferably at least one selected from the group consisting of bisphenol A type epoxy resins, bisphenol F type epoxy resins, and polyoxyalkylene-modified bisphenol type epoxy resins, still more preferably at least one selected from the group consisting of bifunctional bisphenol A type epoxy resins, bifunctional bisphenol F type epoxy resins, and bifunctional polyoxyalkylene-modified bisphenol type epoxy resins, and particularly preferably at least one selected from the group consisting of bifunctional bisphenol A type epoxy resins, bifunctional bisphenol F type epoxy resins, and bifunctional polyoxyalkylene-modified bisphenol A type epoxy resins. In one embodiment, the bisphenol epoxy resin preferably comprises at least one selected from the group consisting of bisphenol A epoxy resins and bisphenol F epoxy resins, more preferably at least one selected from the group consisting of bisphenol A epoxy resins and bisphenol F epoxy resins, even more preferably at least one selected from the group consisting of bifunctional bisphenol A epoxy resins and bifunctional bisphenol F epoxy resins, and particularly preferably consisting solely of bifunctional bisphenol A epoxy resins and bifunctional bisphenol F epoxy resins. In one embodiment, the bisphenol epoxy resin may consist solely of a polyoxyalkylene-modified bisphenol epoxy resin, or may consist solely of a bifunctional polyoxyalkylene-modified bisphenol A epoxy resin.

[0028] In one embodiment, the proportion of the total mass of the bisphenol A epoxy resin and the bisphenol F epoxy resin relative to the total mass of the bisphenol epoxy resins is not particularly limited, but may be 40% by mass or more, 50% by mass or more, 90% by mass or more, or even 100% by mass. When two or more bisphenol A epoxy resins are used in combination, the amount of the bisphenol A epoxy resin represents the total amount. When two or more bisphenol F epoxy resins are used in combination, the amount of the bisphenol F epoxy resin represents the total amount.

[0029] The bisphenol-type epoxy resin may be a commercially available product and / or a synthetic product. Commercially available bisphenol-type epoxy resins include, but are not limited to, jER (registered trademark, the same applies hereinafter) 828, 1001, 801, 806, 807, and YX4000 (manufactured by Mitsubishi Chemical Corporation); Epiclon (registered trademark, the same applies hereinafter) 830, 850, EXA-830CRP, EXA-830LVP, EXA-850CRP, and EXA-835LV (manufactured by DIC Corporation); and Adeka Resin (registered trademark, the same applies hereinafter). EP-4100, EP-4000, EP-4000S, EP-4080, EP-4085, EP-4088, EPU-6, EPU-7N, EPR-4023, EPR-1309, EP-4920 (manufactured by ADEKA Corporation); TEPIC (registered trademark, manufactured by Nissan Chemical Industries, Ltd.); KF-101, KF-1001, KF-105, X-22-163B, X-22-9002 (manufactured by Shin-Etsu Chemical Co., Ltd.); Denacol EX411, 314, 201, 212, 252 (manufactured by Nagase ChemteX Corporation); D.E.R. -331, 332, 334, 431, 542 (manufactured by The Dow Chemical Company); YH-434, YH-434L (manufactured by Nippon Steel Chemical & Material Co., Ltd.); etc. These may be used alone or in combination of two or more.

[0030] In this specification, the term "hydrogenated bisphenol epoxy resin" refers to a compound obtained by hydrogenating the aromatic ring of a bisphenol epoxy resin. The hydrogenated bisphenol epoxy resin is not particularly limited as long as it is a compound obtained by hydrogenating the aromatic ring of a bisphenol epoxy resin. Examples of hydrogenated bisphenol epoxy resins include hydrogenated bisphenol A epoxy resins, hydrogenated bisphenol F epoxy resins, hydrogenated bisphenol E epoxy resins, and hydrogenated bisphenol S epoxy resins. These may be used alone or in combination of two or more. From the viewpoint of achieving superior adhesive strength of the cured product when cured in a short period of time, the hydrogenated bisphenol epoxy resin preferably contains at least one selected from the group consisting of hydrogenated bisphenol A epoxy resins and hydrogenated bisphenol F epoxy resins, more preferably contains hydrogenated bisphenol A epoxy resin, even more preferably consists solely of hydrogenated bisphenol A epoxy resin, and particularly preferably consists solely of bifunctional hydrogenated bisphenol A epoxy resin.

[0031] In one embodiment, the mass ratio of the hydrogenated bisphenol A epoxy resin to the total mass of the hydrogenated bisphenol epoxy resins is not particularly limited, but may be 40 mass% or more, 50 mass% or more, 90 mass% or more, or even 100 mass%. When two or more hydrogenated bisphenol A epoxy resins are used in combination, the amount of the hydrogenated bisphenol A epoxy resin represents the total amount of these.

[0032] The hydrogenated bisphenol epoxy resin may be a commercially available product and / or a synthetic product. Commercially available hydrogenated bisphenol epoxy resins include, for example, ST-3000 (manufactured by Nippon Steel Chemical & Material Co., Ltd.); Rikaresin (registered trademark) HBE-100 (manufactured by New Japan Chemical Co., Ltd.); Epolite 4000 (manufactured by Kyoeisha Chemical Co., Ltd.); jER (registered trademark) YX8000, YX8034 (manufactured by Mitsubishi Chemical Corporation); but are not limited to these. These may be used alone or in combination of two or more types.

[0033] In one embodiment, the ratio of the total mass of the bisphenol A epoxy resin and the bisphenol F epoxy resin to the total mass of the component (A) is not particularly limited, but may be 40% by mass or more, 50% by mass or more, 90% by mass or more, or even 100% by mass. In one embodiment, the ratio of the total mass of the bisphenol A epoxy resin, the bisphenol F epoxy resin, and the polyoxyalkylene-modified bisphenol epoxy resin to the total mass of the component (A) is not particularly limited, but from the viewpoint of the conductivity of the cured product, it is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass. When two or more bisphenol A epoxy resins are used in combination, the amount of the bisphenol A epoxy resin represents the total amount. When two or more bisphenol F epoxy resins are used in combination, the amount of the bisphenol F epoxy resin represents the total amount. When two or more polyoxyalkylene-modified bisphenol-type epoxy resins are used in combination, the amount of the polyoxyalkylene-modified bisphenol-type epoxy resins represents the total amount of these.

[0034] In one embodiment, the mass ratio of the hydrogenated bisphenol A epoxy resin to the total mass of component (A) is not particularly limited, but from the viewpoint of the adhesive strength of the cured product, it is preferably 40 mass% or more, more preferably 50 mass% or more. From the viewpoint of the adhesive strength of the cured product and the electrical conductivity of the cured product, the mass ratio of the hydrogenated bisphenol A epoxy resin to the total mass of component (A) is preferably 60 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, even more preferably 90 mass% or more, and particularly preferably 100 mass%. When two or more hydrogenated bisphenol A epoxy resins are used in combination, the amount of hydrogenated bisphenol A epoxy resin represents the total amount of these.

[0035] The epoxy equivalent of component (A) is not particularly limited, but is preferably 50 g / eq or more and 500 g / eq or less, more preferably 100 g / eq or more and 400 g / eq or less, and even more preferably 150 g / eq or more and 350 g / eq or less. The epoxy equivalent can be measured in accordance with JIS K7236:2009.

[0036] The viscosity of component (A) at 25°C is not particularly limited, but may be, for example, from 1,000 mPa·s to 30,000 mPa·s, from 10,000 mPa·s to 30,000 mPa·s, or from 1,000 mPa·s to less than 10,000 mPa·s. The viscosity at 25°C is measured using a cone-plate rotational viscometer at a shear rate of 10 s in an environment of 25°C and 55% RH. －１ The measured value is expressed as

[0037] The content of the (A) component is not particularly limited, and examples thereof include 5% by mass to 50% by mass, 5% by mass to 30% by mass, and 10% by mass to 20% by mass, relative to the total mass of the conductive resin adhesive. When two or more (A) components are used in combination, the amount of the (A) component represents the total amount thereof.

[0038] [Component (B)] Component (B) is a polyfunctional vinyl ether having a cyclic structure. Component (B) may be a solid or liquid at 25°C, and its state is not particularly limited, as long as it is a compound having a cyclic structure and two or more vinyl ethers (vinyl ether groups) (a compound having a cyclic structure and two or more vinyl ethers (vinyl ether groups) in one molecule). The description of the liquid is the same as above. Component (B) is preferably a liquid at 25°C from the viewpoint of excellent workability. By containing two or more vinyl ethers, a cured product with excellent conductivity can be obtained by curing in a short time. Component (B) may be used alone or in combination of two or more types.

[0039] In this specification, the polyfunctional vinyl ether having a cyclic structure, which is component (B), excludes epoxy resins having two or more glycidyl groups. In this specification, a compound that is included within the scope of the epoxy resin compound having two or more glycidyl groups, which is component (A), and that is also included within the scope of the polyfunctional vinyl ether compound having a cyclic structure, which is component (B), is treated as component (A). That is, in this specification, a polyfunctional vinyl ether having two or more glycidyl groups and a cyclic structure is treated as component (A). It is preferable that the polyfunctional vinyl ether having a cyclic structure, which is component (B), does not have a glycidyl group.

[0040] In this specification, the compound generally used as a silane coupling agent is treated as an optional component, which will be described later.That is, in this specification, even if a vinyl group-containing silane coupling agent has a cyclic structure and has two or more vinyl ether groups, this vinyl group-containing silane coupling agent is not treated as component (B), but as a silane coupling agent.It is preferable that the polyfunctional vinyl ether having a cyclic structure as component (B) does not have silicon.

[0041] In the polyfunctional vinyl ether having a cyclic structure as component (B), the number of vinyl ethers (the number of vinyl ether groups in one molecule) is not particularly limited as long as it is at least 2. The number of vinyl ethers in the polyfunctional vinyl ether having a cyclic structure as component (B) is preferably 2 or more and 6 or less, more preferably 2 or more and 4 or less, and even more preferably 2.

[0042] Examples of the cyclic structure of component (B) include an alicyclic structure, an aromatic ring structure, and a heterocyclic structure. From the viewpoint of the adhesive strength of the cured product and the electrical conductivity of the cured product when cured in a short time, the cyclic structure is preferably an alicyclic structure or an aromatic ring structure, and more preferably an alicyclic structure. An alicyclic ring refers to a saturated or unsaturated carbon ring other than an aromatic ring. The alicyclic structure is preferably a cycloalkane ring, more preferably a cycloalkane ring having 3 to 8 carbon atoms, and even more preferably a cyclohexane ring. In terms of compatibility with component (A), component (B) is preferably liquid at 25°C.

[0043] In one embodiment, the component (B) is preferably a polyfunctional vinyl ether having at least one structure selected from the group consisting of an alicyclic structure, an aromatic ring structure, and a heterocyclic structure, more preferably a polyfunctional vinyl ether having at least one structure selected from the group consisting of an alicyclic structure and an aromatic ring structure, even more preferably a polyfunctional vinyl ether having an alicyclic structure, even more preferably a polyfunctional vinyl ether having only an alicyclic structure as the cyclic structure, still more preferably a polyfunctional vinyl ether having only cycloalkane rings as the cyclic structure, still more preferably a polyfunctional vinyl ether having only cycloalkane rings having 3 to 8 carbon atoms as the cyclic structure, and particularly preferably a polyfunctional vinyl ether having only cyclohexane rings as the cyclic structure.

[0044] From the viewpoint of electrical conductivity of the cured product, the conductive resin adhesive according to one embodiment preferably does not contain a monofunctional vinyl ether.

[0045] Specific examples of component (B) include, but are not limited to, cyclohexanedimethanol divinyl ether, bisphenol divinyl ether, etc. The bisphenol divinyl ether is also not particularly limited, but examples include bisphenol A divinyl ether, bisphenol F divinyl ether, etc. These may be used alone or in combination of two or more. Component (B) preferably contains at least one compound selected from the group consisting of cyclohexanedimethanol divinyl ether and bisphenol divinyl ether, more preferably at least one compound selected from the group consisting of cyclohexanedimethanol divinyl ether, bisphenol A divinyl ether, and bisphenol F divinyl ether, even more preferably cyclohexanedimethanol divinyl ether, and particularly preferably cyclohexanedimethanol divinyl ether.

[0046] Component (B) may be a commercially available product and / or a synthetic product. Commercially available products of component (B) are not particularly limited, but examples thereof include CHDVE (manufactured by Nippon Carbide Industries Co., Ltd.).

[0047] The content of the (B) component is not particularly limited, but is preferably 10 to 150 parts by mass, more preferably 15 to 100 parts by mass, and even more preferably 20 to 60 parts by mass, per 100 parts by mass of the (A) component. When the content of the (B) component is 10 parts by mass or more per 100 parts by mass of the (A) component, a conductive resin adhesive can be obtained that exhibits excellent curability in a short curing time and excellent electrical conductivity of the cured product. When the content of the (B) component is 150 parts by mass or less per 100 parts by mass of the (A) component, a conductive resin adhesive can be obtained that exhibits excellent adhesive strength of the cured product in a short curing time. When two or more (A) components are used in combination, the amount of the (A) component represents the total amount of these components. When two or more (B) components are used in combination, the amount of the (B) component represents the total amount of these components.

[0048] [Component (C)] Component (C) is a conductive particle. The material and shape of the particle of component (C) are not particularly limited as long as they exhibit conductivity. Synthetic products and / or commercially available products may be used as component (C). Component (C) may be used alone or in combination of two or more types.

[0049] The component (C) is not particularly limited, and examples thereof include metal particles composed of one metal selected from gold, silver, copper, nickel, palladium, platinum, tin, bismuth, etc., alloy particles composed of a combination of these metals, and particles whose surfaces are coated with a coating layer of one or more of these metals. The component (C) can be appropriately selected from these particles, for example. These particles may be used alone, or two or more types may be used in combination. From the standpoint of the conductivity and / or cost of the cured product, the component (C) is preferably silver particles or particles whose surfaces (i.e., the surfaces of the particles to be coated) are coated with a coating layer of silver, and silver particles are particularly preferred. Component (C) preferably contains at least one type of particle selected from the group consisting of metal particles made of one type of metal selected from the group consisting of gold, silver, copper, nickel, palladium, platinum, tin, and bismuth metal, alloy particles made of a combination of these metals, and particles in which the surface of the particle to be coated is coated with a coating layer of one or more of these metals; more preferably contains at least one type of particle selected from the group consisting of metal particles made of one type of metal selected from the group consisting of gold, silver, copper, nickel, palladium, platinum, tin, and bismuth metal, and particles in which the surface of the particle to be coated is coated with a coating layer of one or more of these metals; even more preferably contains at least one type of particle selected from the group consisting of silver particles and particles in which the surface of the particle to be coated is coated with a coating layer of silver; even more preferably contains at least one type of particle selected from the group consisting of silver particles and particles in which the surface of the particle to be coated is coated with a coating layer of silver; and particularly preferably contains silver particles.

[0050] The shape of component (C) is not particularly limited, and examples thereof include spherical, irregular, flake, filamentous (needle), and dendritic. The flake shape is preferably a plate-like (plate-like) shape, as described below. Particles of these shapes may be used alone or in combination of two or more. In one embodiment, component (C) preferably contains particles of at least one shape selected from the group consisting of spherical particles, irregular particles, flake-like particles (e.g., plate-like particles), filamentous particles, and dendritic particles, more preferably containing flake-like particles, even more preferably containing plate-like particles, and particularly preferably containing plate-like particles.

[0051] The (C) component may be surface-treated. For example, the (C) component may be surface-treated with a lubricant. Therefore, the conductive particles as the (C) component may be conductive particles surface-treated with a lubricant. The lubricant is not particularly limited, but saturated fatty acids and / or unsaturated fatty acids can be used. Examples of saturated or unsaturated fatty acids include, but are not limited to, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, linolenic acid, palmitoleic acid, oleic acid, malonic acid, and hexanoic acid. These may be used alone or in combination of two or more. However, untreated (C) components (i.e., conductive particles not surface-treated with a lubricant) are preferred because they provide superior adhesive strength and / or conductivity of the cured product in a short curing time. In one embodiment, the component (C) preferably contains conductive particles that have not been surface-treated with a lubricant, and more preferably conductive particles that have not been surface-treated with a lubricant. In one embodiment, the component (C) preferably contains conductive particles that have not been surface-treated, and more preferably conductive particles that have not been surface-treated. In one embodiment, the component (C) preferably contains silver particles that have not been surface-treated, and more preferably silver particles that have not been surface-treated. As the component (C), for example, particles that have been surface-treated with a lubricant, particles that have not been surface-treated with a lubricant, or particles that have not been surface-treated may be used alone, or, for example, two or more types of particles selected from the group consisting of particles that have been surface-treated with a lubricant, particles that have not been surface-treated with a lubricant, and particles that have not been surface-treated may be used in combination.

[0052] The component (C) preferably contains crystalline conductive particles, and more preferably is a crystalline conductive particle. The method for producing the crystalline conductive particles is not particularly limited. The crystalline conductive particles may be produced by a known production method. Examples of the method for producing crystalline conductive particles include a production method, generally referred to as a reduction method, in which a single crystal is grown, as described in JP 2014-196527 A (corresponding to U.S. Patent Application Publication No. 2016 / 001362 A). The shape of the crystalline conductive particles is not particularly limited, but includes, as described above in the shape of the conductive particles, spherical, amorphous, flake-like, filament-like (needle-like), and dendritic shapes.

[0053] In this specification, the term "flake-like shape" refers to a flat shape and is intended to encompass shapes such as a scale-like shape and a plate-like (plate-like) shape as described below. In this specification, a polygonal plate-like shape in which the entire flake (the entire flake-like shape) has a substantially uniform thickness and a substantially smooth surface is also referred to as a "plate-like" shape. The crystalline conductive particles are preferably polygonal plate-like shapes in which the entire flake (the entire flake-like shape) has a substantially uniform thickness and a substantially smooth surface. In other words, the crystalline conductive particles are preferably plate-like (plate-like) particles. Examples of polygonal plate-like shapes are not particularly limited, but include, for example, triangular plate-like shapes, quadrangular plate-like shapes, pentagonal plate-like shapes, and hexagonal plate-like shapes.

[0054] In one embodiment, the crystalline conductive particles preferably include flake-shaped crystalline conductive particles, more preferably plate-shaped crystalline conductive particles, and even more preferably plate-shaped crystalline conductive particles. The crystalline conductive particles are preferably crystalline silver particles, as they provide superior conductivity to the cured product when cured in a short time. In one embodiment, component (C) preferably includes crystalline silver particles, more preferably crystalline silver particles, even more preferably flake-shaped crystalline silver particles, even more preferably plate-shaped crystalline silver particles, and particularly preferably unsurface-treated plate-shaped crystalline silver particles. Whether the conductive particles of component (C) are crystalline particles can be determined, for example, by observing their shape using a scanning electron microscope (SEM).

[0055] The crystalline conductive particles may be commercially available products and / or synthetic products. Examples of commercially available crystalline conductive particles include, but are not limited to, N300, M612, M13, M27, and LM1 (manufactured by Tokusen Kogyo Co., Ltd.).

[0056] As component (C), crystalline conductive particles and non-crystalline conductive particles may be used in combination. When crystalline conductive particles and non-crystalline conductive particles are used in combination, the weight ratio (mass ratio) of the crystalline conductive particles to the non-crystalline conductive particles is preferably 10:90 to 90:10 (crystalline conductive particles:non-crystalline conductive particles), more preferably 10:90 to 75:25 (crystalline conductive particles:non-crystalline conductive particles), and even more preferably 15:85 to 50:50 (crystalline conductive particles:non-crystalline conductive particles). By satisfying the above range, a conductive resin adhesive can be obtained that exhibits excellent conductivity in a cured product cured in a short time. When two or more types of crystalline conductive particles are used in combination, the amount of the crystalline conductive particles represents the total amount thereof. When two or more types of non-crystalline conductive particles are used in combination, the amount of the non-crystalline conductive particles represents the total amount thereof.

[0057] The shape of the non-crystalline conductive particles is not particularly limited, but as described above in the description of the shape of the conductive particles, examples include spherical, amorphous, flaky (e.g., scale-like), filamentous (needle-like), and dendritic shapes. These non-crystalline conductive particles may be used alone, or two or more types may be used in combination. From the viewpoint of superior conductivity, the non-crystalline conductive particles preferably include flaky or spherical non-crystalline conductive particles. Examples of non-crystalline conductive particles include, but are not limited to, flaky conductive particles obtained by a pulverization process, and conductive particles in which the surfaces of organic or inorganic particles are coated with a conductive metal. The non-crystalline conductive particles are preferably silver particles or particles in which the surfaces of the particles to be coated are coated with a silver coating layer, from the viewpoint of superior conductivity of the cured product when cured in a short time.

[0058] The average particle size of component (C) is not particularly limited, but is preferably in the range of 0.01 to 100 μm, more preferably 0.1 to 50 μm, even more preferably 0.1 to 30 μm, and particularly preferably 0.3 to 10 μm. Here, the average particle size of component (C) is the particle size (D50) at a cumulative volume ratio of 50% in the particle size distribution determined by laser diffraction scattering. When two or more types of conductive particles are contained as component (C), the above average particle size represents the average particle size of each individual conductive particle. The average particle size of the crystalline conductive particles is preferably in the range of 0.01 to 100 μm, more preferably 0.1 to 50 μm, even more preferably 0.01 to 30 μm, even more preferably 0.1 to 20 μm, and particularly preferably 0.3 to 10 μm, from the viewpoint of superior conductivity. Here, the average particle size of the crystalline conductive particles is the particle size (D50) at a cumulative volume ratio of 50% in the particle size distribution determined by laser diffraction scattering. When two or more types of crystalline conductive particles are included as component (C), the above average particle size represents the average particle size of each crystalline conductive particle. The average particle size of the non-crystalline conductive particles is preferably in the range of 0.1 to 50 μm, more preferably in the range of 0.1 to 30 μm, even more preferably 1 to 20 μm, and particularly preferably 1 to 15 μm. The average particle size of the non-crystalline conductive particles is the particle size at a cumulative volume ratio of 50% (D50) in the particle size distribution determined by laser diffraction scattering. When two or more types of non-crystalline conductive particles are included as component (C), the above average particle size represents the average particle size of each non-crystalline conductive particle.

[0059] The content of the (C) component is not particularly limited, but is preferably 200 to 1,000 parts by mass, more preferably 300 to 800 parts by mass, and even more preferably 350 to 700 parts by mass, per 100 parts by mass of the (A) component. When the content of the (C) component is 200 parts by mass or more per 100 parts by mass of the (A) component, a conductive resin adhesive can be obtained that exhibits excellent conductivity of the cured product when cured in a short period of time. When the content of the (C) component is 1,000 parts by mass or less per 100 parts by mass of the (A) component, a conductive resin adhesive with excellent workability can be obtained. When two or more (A) components are used in combination, the amount of the (A) component represents the total amount thereof. When two or more (C) components are used in combination, the amount of the (C) component represents the total amount thereof.

[0060] The content of component (C) is not particularly limited, but is preferably 40 to 95 mass %, more preferably 50 to 90 mass %, and even more preferably 60 to 85 mass %, of the entire conductive resin adhesive. By being in the above range, a conductive resin adhesive can be obtained that is excellent in workability and has excellent conductivity of the cured product when cured in a short time. When two or more types of component (C) are used in combination, the amount of component (C) represents the total amount of these.

[0061] [Component (D)] Component (D) is a thermal cationic polymerization initiator. A thermal cationic polymerization initiator is a compound that generates cationic species upon heating. Component (D) may be used alone or in combination of two or more types.

[0062] The component (D) is not particularly limited, but examples thereof include a thermal cationic polymerization initiator containing a salt of a hexafluoroantimonate anion and a cation, a thermal cationic polymerization initiator containing a salt of a hexafluorophosphate anion and a cation, a thermal cationic polymerization initiator containing a salt of a tetrakis(pentafluorophenyl)borate anion and a cation, and a boron trifluoride derivative. Among these, from the viewpoint of obtaining a conductive resin adhesive that exhibits less warping when bonding different materials and has superior adhesive strength of the cured product, a thermal cationic polymerization initiator containing a salt of a tetrakis(pentafluorophenyl)borate anion and a cation and a boron trifluoride derivative are preferred, and a thermal cationic polymerization initiator containing a salt of a tetrakis(pentafluorophenyl)borate anion and a cation is more preferred. These may be used alone, or two or more may be used in combination. Component (D) preferably contains at least one thermal cationic polymerization initiator selected from the group consisting of a thermal cationic polymerization initiator containing a salt of a hexafluoroantimonate anion and a cation, a thermal cationic polymerization initiator containing a salt of a hexafluorophosphate anion and a cation, a thermal cationic polymerization initiator containing a salt of a tetrakis(pentafluorophenyl)borate anion and a cation, and a boron trifluoride derivative; more preferably contains at least one thermal cationic polymerization initiator selected from the group consisting of a thermal cationic polymerization initiator containing a salt of a tetrakis(pentafluorophenyl)borate anion and a cation, and a boron trifluoride derivative; still more preferably contains a thermal cationic polymerization initiator containing a salt of a tetrakis(pentafluorophenyl)borate anion and a cation; and particularly preferably contains a thermal cationic polymerization initiator containing a salt of a tetrakis(pentafluorophenyl)borate anion and a cation. The cation is not particularly limited, but examples thereof include a quaternary ammonium cation and a sulfonium ion in which at least one of the three groups bonded to the sulfur atom is an alkyl group having 1 to 8 carbon atoms, and a quaternary ammonium cation is preferred. These may be used alone or in combination of two or more.The cations contained in the thermal cationic polymerization initiator as component (D) (herein also referred to as the cationic species of component (D)) preferably contain at least one type of cation selected from the group consisting of quaternary ammonium cations and sulfonium ions in which at least one of the three groups bonded to the sulfur atom is an alkyl group having 1 to 8 carbon atoms, more preferably contain a quaternary ammonium cation, and even more preferably be a quaternary ammonium cation.

[0063] A preferred example of a thermal cationic polymerization initiator containing a salt of a tetrakis(pentafluorophenyl)borate anion and a cation is a thermal cationic polymerization initiator containing a salt of a tetrakis(pentafluorophenyl)borate anion and a quaternary ammonium cation, from the viewpoint of obtaining a conductive resin adhesive that exhibits less warping when bonding different materials and exhibits excellent adhesive strength when cured in a short time. Examples of boron trifluoride derivatives include, but are not limited to, boron trifluoride monomethylamine, boron trifluoride monoethylamine (boron trifluoride monoethylamine), and boron trifluoride monopropylamine. These may be used alone or in combination of two or more. The component (D) preferably includes at least one selected from the group consisting of a thermal cationic polymerization initiator containing a salt formed from a tetrakis(pentafluorophenyl)borate anion and a quaternary ammonium cation, boron trifluoride monomethylamine, boron trifluoride monoethylamine (boron trifluoride monoethylamine), and boron trifluoride monopropylamine, more preferably a thermal cationic polymerization initiator containing a salt formed from a tetrakis(pentafluorophenyl)borate anion and a quaternary ammonium cation, and even more preferably a thermal cationic polymerization initiator containing a salt formed from a tetrakis(pentafluorophenyl)borate anion and a quaternary ammonium cation.

[0064] Component (D) may be a commercially available product and / or a synthetic product. Commercially available thermal cationic polymerization initiators containing a salt formed from a hexafluoroantimonate anion and a cation include, but are not limited to, SI-60L, SI-80L, and SI-100L manufactured by Sanshin Chemical Industry Co., Ltd. Commercially available thermal cationic polymerization initiators containing a salt formed from a hexafluorophosphate anion and a cation include, but are not limited to, SI-110L, SI-180L, SI-B2A, and SI-B3A manufactured by Sanshin Chemical Industry Co., Ltd. Commercially available thermal cationic polymerization initiators containing a salt formed from a tetrakis(pentafluorophenyl)borate anion and a cation include, but are not limited to, K-PURE (registered trademark) CXC-1821 manufactured by King Industries. Furthermore, commercially available boron trifluoride derivatives are not particularly limited, and examples thereof include boron trifluoride monoethylamine manufactured by Stella Chemifa Co., Ltd. These may be used alone or in combination of two or more.

[0065] The content of the (D) component is not particularly limited, but is preferably 1 to 30 parts by mass, more preferably 5 to 25 parts by mass, and even more preferably 10 to 20 parts by mass, per 100 parts by mass of the (A) component. When the content of the (D) component is 1 part by mass or more per 100 parts by mass of the (A) component, excellent short-term curing properties are achieved. When the content of the (D) component is 30 parts by mass or less per 100 parts by mass of the (A) component, a conductive resin adhesive can be obtained that exhibits excellent conductivity of the cured product upon short-term curing. When two or more (A) components are used in combination, the amount of the (A) component represents the total amount thereof. When two or more (D) components are used in combination, the amount of the (D) component represents the total amount thereof.

[0066] [Optional Components] In addition to the components described above, various additives can be added as optional components to the conductive resin adhesive according to this embodiment, as needed, as long as the effects of the present invention are not impaired. That is, the conductive resin adhesive according to this embodiment may contain optional components in addition to the components described above, or may not contain optional components in addition to the components described above. The optional additives are not particularly limited, but examples include monofunctional reactive diluents, silane coupling agents, plasticizers, fillers (excluding conductive particles), storage stabilizers, tackifiers, metal complexes, organic pigments, inorganic pigments, rust inhibitors, antifoaming agents, dispersants, surfactants, viscoelasticity adjusters, thickeners, and radically polymerizable compounds (excluding both polyfunctional vinyl ethers having a cyclic structure and silane coupling agents).

[0067] (Monofunctional reactive diluent) The conductive resin adhesive according to this embodiment may further contain a monofunctional reactive diluent, or may not further contain a monofunctional reactive diluent. The monofunctional reactive diluent is an epoxy resin having one glycidyl group. That is, the monofunctional reactive diluent is a compound having one glycidyl group. The monofunctional reactive diluent differs from component (A) in that it has only one glycidyl group.

[0068] In this specification, a compound having one glycidyl group that is also included in component (B) is treated as component (B). That is, in this specification, a polyfunctional vinyl ether having one glycidyl group and a cyclic structure is treated as component (B).

[0069] In this specification, even when a glycidyl group-containing silane coupling agent has one glycidyl group, the glycidyl group-containing silane coupling agent is not treated as a monofunctional reactive diluent but as a silane coupling agent.

[0070] Although the inclusion of a monofunctional reactive diluent in the conductive resin adhesive according to one embodiment allows for the production of a conductive resin adhesive with excellent workability, outgassing is likely to occur. Therefore, the conductive resin adhesive according to one embodiment preferably does not substantially contain a monofunctional reactive diluent, and more preferably does not contain a monofunctional reactive diluent. The content of the reactive diluent is not particularly limited, but is, for example, preferably 10% by mass or less, more preferably 1% by mass or less, even more preferably 0.1% by mass or less, and particularly preferably 0% by mass, relative to the entire conductive resin adhesive. In this specification, "the conductive resin adhesive is substantially free of a reactive diluent" means that the content of the reactive diluent is 0.1% by mass or less relative to the entire conductive resin adhesive. In this specification, "the conductive resin adhesive does not contain a reactive diluent" means that the content of the reactive diluent is 0% by mass relative to the entire conductive resin adhesive. When two or more monofunctional reactive diluents are used in combination, the amount of the monofunctional reactive diluent refers to the total amount of these.

[0071] The monofunctional reactive diluent is not particularly limited, and examples thereof include glycidyl ethers such as methyl glycidyl ether, ethyl glycidyl ether, butyl glycidyl ether, isobutyl glycidyl ether, phenyl glycidyl ether, 2-ethylhexyl glycidyl ether, decyl glycidyl ether, stearyl glycidyl ether, allyl glycidyl ether, 2-methyloctyl glycidyl ether, methoxypolyethylene glycol monoglycidyl ether, ethoxypolyethylene glycol monoglycidyl ether, butoxypolyethylene glycol monoglycidyl ether, phenoxypolyethylene glycol monoglycidyl ether, p-tert-butylphenyl glycidyl ether, sec-butylphenyl glycidyl ether, n-butylphenyl glycidyl ether, phenylphenol glycidyl ether, cresyl glycidyl ether, and dibromocresyl glycidyl ether; and glycidyl esters such as neodecanoic acid glycidyl ester. These may be used alone or in combination of two or more.

[0072] (Silane Coupling Agent) The conductive resin adhesive according to this embodiment may or may not further contain a silane coupling agent. The silane coupling agent is not particularly limited, and examples thereof include glycidyl group-containing silane coupling agents such as 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropylmethyldiethoxysilane; vinyl group-containing silane coupling agents such as vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, and vinyltrimethoxysilane; (meth)acrylic group-containing silane coupling agents (acryloyl group and / or methacryloyl group-containing silane coupling agents) such as γ-methacryloxypropyltrimethoxysilane; amino group-containing silane coupling agents such as N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane; γ-mercaptopropyltrimethoxysilane; γ-chloropropyltrimethoxysilane; and oligomers thereof. Among these, glycidyl group-containing silane coupling agents are preferred in terms of excellent adhesion. These may be used alone or in combination of two or more.

[0073] In this specification, the glycidyl group-containing silane coupling agent is not treated as component (A) or a monofunctional reactive diluent, but as a silane coupling agent.Therefore, in this specification, even if the glycidyl group-containing silane coupling agent has one glycidyl group, the glycidyl group-containing silane coupling agent is not treated as a monofunctional reactive diluent, but as a silane coupling agent.In addition, in this specification, even if the glycidyl group-containing silane coupling agent has two or more glycidyl groups, the glycidyl group-containing silane coupling agent is not treated as component (A), but as a silane coupling agent.In this specification, even if the glycidyl group-containing silane coupling agent has two or more glycidyl groups, the glycidyl group-containing silane coupling agent is not treated as an epoxy resin having two or more glycidyl groups, but as a silane coupling agent.

[0074] In this specification, the vinyl group-containing silane coupling agent is not considered as component (B) but is considered as a silane coupling agent. That is, in this specification, even if the vinyl group-containing silane coupling agent has a cyclic structure and two or more vinyl ether groups, the vinyl group-containing silane coupling agent is not considered as component (B) but is considered as a silane coupling agent.

[0075] In this specification, a silane coupling agent having a radically polymerizable functional group is not treated as a radically polymerizable compound, which will be described later, but as a silane coupling agent.

[0076] Commercially available silane coupling agents include, but are not limited to, KBM-1003, KBE-1003, KBM-303, KBM-403, KBE-403, KBM-502, KBE-502, KBM-503, KBE-503, KBM-5103, KBM-1403, KBM-602, KBM-603, KBM-903, and KBE-903 (manufactured by Shin-Etsu Chemical Co., Ltd.); DOWSIL Z-6610, DOWSIL Z-6044, DOWSIL Z-6825, DOWSIL Z-6033, and DOWSIL Z-6062 (manufactured by Dow-Toray Industries, Inc.); and the like.

[0077] (Filler) The conductive resin adhesive according to this embodiment may or may not further contain a filler. In this specification, the term "filler" refers to a filler excluding conductive particles (i.e., a filler other than conductive particles). The filler is not particularly limited, but examples include glass, silica, talc, mica, ceramics, calcium carbonate, carbon powder, kaolin clay, dried clay minerals, dried diatomaceous earth, and rubber particles. Rubber particles are preferred as the filler because the addition of the filler has less effect on the conductivity of the cured product.

[0078] In this specification, rubber particles are particles including a layer exhibiting rubber elasticity. The rubber particles may be particles consisting of only one layer exhibiting rubber elasticity, or may be core-shell particles, which are particles with a multilayer structure exhibiting rubber elasticity. For reasons unknown, core-shell particles are preferred as rubber particles in terms of their excellent resin resistance (also called volume resistivity). Rubber particles pre-dispersed in an epoxy resin may also be used. The rubber constituting the rubber particles is not particularly limited, but examples thereof include butadiene rubber, acrylic rubber, silicone rubber, butyl rubber, olefin rubber, styrene rubber, NBR, SBR, IR, and EPR. These may be used alone or in combination of two or more.

[0079] In this specification, core-shell particles are particles in which the core (nucleus) and shell (wall) portions of the particles are made of polymers with different properties. In a preferred method for producing powder particles, the core portion is first produced by polymerizing a polymerizable monomer. Examples of polymerizable monomers used to form the core portion are not particularly limited, but include (meth)acrylate monomers such as n-propyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-decyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and butoxyethyl (meth)acrylate; aromatic vinyl compounds such as styrene, vinyltoluene, and α-methylstyrene; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; vinylidene cyanide; 2-hydroxyethyl fumarate; hydroxybutyl vinyl ether; and monobutyl maleate. Examples of polymerizable monomers used to form the core portion include crosslinkable monomers having two or more reactive groups, such as ethylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, hexanediol tri(meth)acrylate, oligoethylene di(meth)acrylate, and oligoethylene tri(meth)acrylate; aromatic divinyl monomers such as divinylbenzene; triallyl trimellitate; and triallyl isocyanurate. These may be used alone or in combination of two or more different types. Next, the polymer particles thus obtained are used as cores, and a second polymerization is carried out in which a polymerizable monomer is polymerized to form a shell made of a polymer having a melting point above room temperature. The polymerizable monomer used in this process (the polymerizable monomer used to form the shell) is not particularly limited, and may be, for example, one or two or more different types selected from the same polymerizable monomers used to obtain the core.Preferred examples of polymerizable monomers used as shell materials include alkyl(meth)acrylates in which the alkyl group has 1 to 4 carbon atoms, such as ethyl(meth)acrylate, n-butyl acrylate, methyl methacrylate, and butyl methacrylate.

[0080] The core-shell particles may be synthesized by the above-mentioned production method, or commercially available ones may be used. Examples of commercially available core-shell particles include, but are not limited to, Paraloid EXL-2655 (manufactured by Kureha Corporation) made of a butadiene-alkyl methacrylate-styrene copolymer; Stafiloid (registered trademark, the same applies hereinafter) AC-3355, Stafiloid AC3364, Stafiloid TR-2105, Stafiloid TR-2102, Stafiloid TR-2122, Stafiloid IM-101, Stafiloid IM-203, Stafiloid IM-301, Stafiloid IM-401, and Stafiloid IM-406 made of an acrylic acid ester-acrylonitrile-styrene copolymer; and Zefiac made of a polymethacrylic acid ester polymer. F-351G (manufactured by Aica Kogyo Co., Ltd.), Paraloid EXL-2314, EXL-2611, EXL-3387 (manufactured by Dow Chemical Japan Co., Ltd.), etc. These may be used alone or in combination of two or more.

[0081] As the core-shell particles, (meth)acrylic core-shell particles composed of an acrylic acid ester / methacrylic acid ester (co)polymer and / or a polymethacrylic acid ester (co)polymer, etc. are preferred because they are effective even when added in small amounts. In this specification, the term "(co)polymer" is a general term that includes copolymers and homopolymers.

[0082] Specific examples of rubber particles pre-dispersed in an epoxy resin include rubber particles dispersed in an epoxy resin using a mixing / stirring device such as a hyper or homogenizer, and rubber particles synthesized in an epoxy resin by emulsion polymerization. These may be used alone or in combination of two or more. If the epoxy resin in which the rubber particles are dispersed has two or more glycidyl groups, the epoxy resin is treated as the aforementioned component (A). If the epoxy resin in which the rubber particles are dispersed has one glycidyl group, the epoxy resin is treated as the aforementioned monofunctional reactive diluent. However, if the epoxy resin in which the rubber particles are dispersed is a silane coupling agent, the epoxy resin is treated as a silane coupling agent.

[0083] Commercially available rubber-dispersed epoxy resins are not particularly limited, and examples thereof include Kane Ace (registered trademark) MX-153, MX-136, MX-257, MX-127, and MX-451 (manufactured by Kaneka Corporation); Acryset (registered trademark) BPF-307 and BPA-328 (manufactured by Nippon Shokubai Co., Ltd.); and the like. These may be used alone or in combination of two or more.

[0084] The particle size of the rubber particles is not particularly limited, but is preferably 0.01 to 10 μm, and particularly preferably 0.05 to 5 μm. When the rubber particles are 0.01 μm or more, an increase in viscosity can be suppressed. When the rubber particles are 10 μm or less, a conductive resin adhesive with excellent conductivity in the cured product can be obtained.

[0085] The content of the rubber particles is not particularly limited, but is preferably 0.01 to 20 parts by mass, and more preferably 0.05 to 10 parts by mass, per 100 parts by mass of the (A) component. When the content of the rubber particles is 0.01 part by mass or more per 100 parts by mass of the (A) component, a conductive resin adhesive with excellent conductivity of the cured product can be obtained. When the content of the rubber particles is 20 parts by mass or less per 100 parts by mass of the (A) component, a conductive resin adhesive with excellent workability can be obtained. When two or more types of (A) components are used in combination, the amount of the (A) component represents the total amount thereof. When two or more types of rubber particles are used in combination, the amount of the rubber particles represents the total amount thereof.

[0086] (Storage Stabilizer) The conductive resin adhesive according to this embodiment may further contain a storage stabilizer, or may not further contain a storage stabilizer. The storage stabilizer is not particularly limited as long as it improves storage stability. Examples of storage stabilizers that may be blended include borate ester compounds, phosphoric acid, alkyl phosphate esters, p-toluenesulfonic acid, and methyl p-toluenesulfonate. Examples of borate ester compounds include trimethyl borate, triethyl borate, tri-n-propyl borate, triisopropyl borate, tributyl borate, trihexyl borate, tri-n-octyl borate, tris(2-ethylhexyloxy)borane, triphenyl borate, and trimethoxyboroxine. Commercially available borate ester compounds are not particularly limited, but examples include "Cureduct (registered trademark) L-07N" (manufactured by Shikoku Chemicals Corporation). Examples of alkyl phosphate esters that can be used include, but are not limited to, trimethyl phosphate and tributyl phosphate. The storage stabilizer may be used alone or in combination. In consideration of storage stability, the storage stabilizer is preferably phosphoric acid, tributyl borate, trimethoxyboroxine, and / or methyl p-toluenesulfonate.

[0087] (Radical Polymerizable Compound) The conductive resin adhesive according to this embodiment may further contain a radical polymerizable compound, or may not further contain a radical polymerizable compound. In this specification, the term "radical polymerizable compound" excludes compounds having a glycidyl group, polyfunctional vinyl ethers having a cyclic structure, and silane coupling agents. That is, in this specification, the term "radical polymerizable compound" refers to a compound having radical polymerizability that is not a compound having a glycidyl group, not a polyfunctional vinyl ether having a cyclic structure, or not a silane coupling agent. In this specification, a silane coupling agent having a radical polymerizable functional group is treated as the aforementioned silane coupling agent, not as a radical polymerizable compound. In this specification, a polyfunctional vinyl ether having a cyclic structure is treated as the aforementioned component (B), not as a radical polymerizable compound. Although the reason is unclear, the inclusion of a radical polymerizable compound in the conductive resin adhesive improves the curability of the conductive resin adhesive and / or the flexibility of the cured product. The radical polymerizable compound is not particularly limited, but examples thereof include monofunctional (meth)acrylic monomers, polyfunctional (meth)acrylic monomers, (meth)acrylic oligomers, and cyclopolymerizable monomers. These may be used alone or in combination of two or more.

[0088] [Organic Solvent] The conductive resin adhesive according to this embodiment may or may not further contain an organic solvent. In this specification, the term "organic solvent" refers to a compound generally used as an organic solvent, other than the components (A) to (D) and the optional components listed above. In other words, even if the components (A) to (D) and the optional components listed above are liquid compounds, these liquid compounds are treated as substances different from organic solvents. The conductive resin adhesive according to one embodiment preferably contains substantially no organic solvent, and more preferably no organic solvent. In this specification, "substantially no organic solvent" refers to a conductive resin adhesive containing 1% by mass or less of the organic solvent relative to the entire conductive resin adhesive. In this specification, "no organic solvent" refers to a conductive resin adhesive containing 0% by mass of the organic solvent relative to the entire conductive resin adhesive. The organic solvent content is not particularly limited, but is preferably 1% by mass or less, more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, and particularly preferably 0% by mass relative to the entire conductive resin adhesive. When the conductive resin adhesive contains an organic solvent, depending on the composition of the conductive resin adhesive, the organic solvent may dissolve the component (D), resulting in a deterioration in storage stability and / or separation of the organic solvent from the conductive resin adhesive, which may affect the physical properties. On the other hand, if the content of the organic solvent is 1 mass% or less relative to the entire conductive resin adhesive, the storage stability tends to be improved and / or separation from the conductive resin adhesive tends to be more unlikely. In one embodiment, the content of the organic solvent may be more than 1 mass% relative to the entire conductive resin adhesive. When two or more organic solvents are used in combination, the amount of organic solvent refers to the total amount of these.

[0089] The organic solvent is not particularly limited, but examples thereof include aromatic organic solvents such as toluene and xylene; aliphatic organic solvents such as n-hexane; alicyclic organic solvents such as cyclohexane, methylcyclohexane, and ethylcyclohexane; ketone organic solvents such as acetone and methyl ethyl ketone; alcohol organic solvents such as methanol and ethanol; ester organic solvents such as ethyl acetate and butyl acetate; and propylene glycol ether organic solvents such as propylene glycol methyl ether, propylene glycol ethyl ether, and propylene glycol-t-butyl ether.

[0090] [Method for Producing Conductive Resin Adhesive] The method for producing the conductive resin adhesive according to this embodiment is not particularly limited, and examples thereof include a method comprising mixing the components (A) to (D). In one embodiment, the method for producing the conductive resin adhesive preferably comprises mixing the components (A) to (D), but does not include adding the monofunctional reactive diluent or adding the organic solvent. In one embodiment, the method for producing the conductive resin adhesive more preferably comprises mixing the components (A) to (D), but does not include adding any component other than the components (A) to (D). Optionally, the method may further comprise mixing the components (A) to (D) with at least one component selected from the group consisting of the optional components and the organic solvent.

[0091] The mixing order, mixing method, and mixing conditions of the components are not particularly limited. The mixing order is preferably such that the components (A) to (C) are mixed to obtain a mixture, and then the resulting mixture is mixed with the component (D). Therefore, in one embodiment, the method for producing a conductive resin adhesive preferably includes mixing the components (A) to (C) to obtain a mixture, and mixing the resulting mixture with the component (D). In one embodiment, the method for producing a conductive resin adhesive preferably includes mixing the components (A) to (C) to obtain a mixture, and mixing the resulting mixture with the component (D), but does not include adding the monofunctional reactive diluent or adding the organic solvent. In one embodiment, the method for producing a conductive resin adhesive more preferably includes mixing the components (A) to (C) to obtain a mixture, and mixing the resulting mixture with the component (D), but does not include adding any components other than the components (A) to (D).

[0092] [Method for curing conductive resin adhesive and cured product of conductive resin adhesive] A cured product can be obtained by curing the conductive resin adhesive according to this embodiment. The conductive resin adhesive according to one embodiment can be cured by short-term heating (less than 10 minutes). Among the curing conditions for the conductive resin adhesive, the heating temperature (heat curing temperature) is not particularly limited. However, from the viewpoint of minimizing damage to the adherend, for example, a temperature of 100 to 180°C is preferred, and a temperature of 130 to 150°C is more preferred. Among the curing conditions for the conductive resin adhesive, the heat curing time is not particularly limited. However, from the viewpoint of production efficiency, for example, in a method for producing a cured product using a conductive resin adhesive or a product containing the same, 1 second to 10 minutes is preferred, 1 second to 5 minutes is more preferred, and 3 seconds to 3 minutes is even more preferred. Furthermore, after the heating step according to the above curing conditions, an additional heating step at a low temperature (less than 100°C) may be further included. By including an additional heating step, a cured product with superior adhesive strength and / or conductivity can be obtained. The temperature conditions (heating temperature, heat-curing temperature) of the additional heating step are not particularly limited, but are preferably from 45 to less than 100°C, more preferably from 50 to 95°C. The heat-curing time of the additional heating step is not particularly limited, but when the heat-curing temperature is from 45 to less than 100°C, 10 minutes to 3 hours is preferred, and 30 minutes to 2 hours is more preferred. A cured product obtained by curing the conductive resin adhesive according to this aspect is also part of an embodiment of the present invention. Therefore, it can be said that another aspect of the present invention relates to a cured product obtained by curing the conductive resin adhesive according to the above aspect (a cured product obtained by curing the conductive resin adhesive according to the above aspect). Details of the conductive resin adhesive according to the above aspect for forming the cured product according to this aspect are as described above.

[0093] In one embodiment, the lower the resistance value of the conductive resin adhesive cured by heating at 130°C for 3 minutes (the conductive resin adhesive cured at 130°C for 3 minutes), the better. In one embodiment, the conductivity (resistance value) of the conductive resin adhesive cured at 130°C for 3 minutes is preferably 1.0Ω or less, more preferably 0.5Ω or less, even more preferably 0.3Ω or less, and particularly preferably 0.2Ω or less (lower limit 0Ω). Therefore, by curing the conductive resin adhesive of one embodiment by heating at 130°C for 3 minutes, a cured product having a conductivity of preferably 0.3Ω or less, more preferably 1.0Ω or less, even more preferably 0.5Ω or less, even more preferably 0.3Ω or less, and particularly preferably 0.2Ω or less can be obtained. The lower limit of conductivity is 0Ω.

[0094] In one embodiment, the electrical conductivity of a cured product obtained by heating at 130°C for 3 minutes and then heating at 80°C for 60 minutes (a cured product obtained by curing a conductive resin adhesive at 130°C for 3 minutes + 80°C for 60 minutes) is preferably as low as possible. In one embodiment, the electrical conductivity (resistance) of a cured product obtained by curing a conductive resin adhesive at 130°C for 3 minutes + 80°C for 60 minutes is preferably 1.0Ω or less, more preferably 0.5Ω or less, even more preferably 0.3Ω or less, even more preferably 0.2Ω or less, and particularly preferably 0.1Ω or less (lower limit: 0Ω). Therefore, in one embodiment, by curing the conductive resin adhesive at 130°C for 3 minutes and 80°C for 60 minutes, a cured product having a conductivity of preferably 1.0Ω or less can be obtained, more preferably 0.5Ω or less, even more preferably 0.3Ω or less, still more preferably 0.2Ω or less, and particularly preferably 0.1Ω or less. The lower limit of the conductivity is 0Ω.

[0095] In this specification, the resistance value of a cured product of a conductive resin adhesive is a value measured and calculated by the following method. First, for a test piece including an electroless nickel-plated plate and five cured products arranged at a predetermined interval on the surface of the electroless nickel-plated plate, the needle electrodes of a dual display multimeter are brought into contact with adjacent cured products to measure the resistance values ​​of each of the four pairs of adjacent cured products. The average of these resistance values ​​is then taken as the resistance value of the cured product (the resistance value of the cured product of the conductive resin adhesive). Details of the method for measuring the conductivity of a conductive resin adhesive are described in the Examples.

[0096] In one embodiment, the adhesive strength of a cured product obtained by heating the conductive resin adhesive for 3 minutes at 130°C (a cured product obtained by curing the conductive resin adhesive at 130°C for 3 minutes) is preferably as high as possible. In one embodiment, the adhesive strength of a cured product obtained by curing the conductive resin adhesive at 130°C for 3 minutes is preferably 10 MPa or more, more preferably 12 MPa or more, even more preferably 14 MPa or more, even more preferably 18 MPa or more, even more preferably more than 19 MPa, even more preferably 24 MPa or more, and particularly preferably 28 MPa or more. Therefore, in one embodiment, by curing the conductive resin adhesive at 130°C for 3 minutes, a cured product having an adhesive strength of preferably 10 MPa or more can be obtained, more preferably 12 MPa or more can be obtained, even more preferably 14 MPa or more can be obtained, even more preferably 18 MPa or more can be obtained, even more preferably 19 MPa or more can be obtained, even more preferably 24 MPa or more can be obtained, and particularly preferably 28 MPa or more can be obtained.

[0097] In one embodiment, the adhesive strength of a cured product obtained by heating at 130°C for 3 minutes and then at 80°C for 60 minutes (a cured product obtained by curing a conductive resin adhesive at 130°C for 3 minutes + 80°C for 60 minutes) is preferably as high as possible. In one embodiment, the adhesive strength of a cured product obtained by curing a conductive resin adhesive at 130°C for 3 minutes + 80°C for 60 minutes is preferably 10 MPa or more, more preferably 12 MPa or more, even more preferably 14 MPa or more, even more preferably 18 MPa or more, even more preferably more than 19 MPa, even more preferably 24 MPa or more, and particularly preferably 28 MPa or more. Therefore, in one embodiment, by curing the conductive resin adhesive at 130°C for 3 minutes and 80°C for 60 minutes, a cured product having an adhesive strength of preferably 10 MPa or more can be obtained, more preferably 12 MPa or more can be obtained, even more preferably 14 MPa or more can be obtained, even more preferably 18 MPa or more can be obtained, even more preferably 19 MPa or more can be obtained, even more preferably 24 MPa or more can be obtained, and particularly preferably 28 MPa or more can be obtained.

[0098] The adhesive strength of the cured conductive resin adhesive is a value measured and calculated by the following method. First, a test piece is formed by bonding an electroless nickel-plated plate and a ceramic chip (material: alumina, 2φ (2 mm diameter) × 1 mm) with the cured product. With the electroless nickel-plated plate fixed, a digital force gauge with contacts is moved at 50 mm / min to press the tip with the contacts perpendicular to the long side of the test piece, measuring the maximum strength. The adhesive strength is then calculated from the maximum strength value converted from the adhesive area. The average adhesive strength of five test pieces measured by the above method is taken as the adhesive strength of the cured product (adhesion strength of the cured conductive resin adhesive). Details of the method for measuring the adhesive strength of the conductive resin adhesive are described in the Examples.

[0099] <Uses of the Conductive Resin Adhesive and Its Cured Product> The uses of the conductive resin adhesive according to the above embodiment are not particularly limited. The conductive resin adhesive according to the above embodiment can be cured by heating for a short period of time, and therefore can be used for components using heat-sensitive components (e.g., plastics, etc.). Therefore, the conductive resin adhesive according to a preferred embodiment can also be used, without particular limitation, for bonding heat-sensitive components (e.g., plastics, etc.) that cannot be heated for long periods of time to the heat-sensitive components or components other than the heat-sensitive components. Examples of components using heat-sensitive components (e.g., plastics, etc.) are not particularly limited, but specific examples include liquid crystal image display elements, organic EL elements, solar cell elements, camera modules, flexible printed circuit boards, wearables, battery packs, etc.

[0100] The conductive resin adhesive according to the above aspect can be used in electronic components, etc., that require conductivity. Among these, the conductive resin adhesive according to one embodiment is preferably used for electronic components including an adherend having poorly conductive nickel as its outermost surface, due to the excellent conductivity and adhesive strength of the cured product. In electronic components including an adherend having poorly conductive nickel as its outermost surface, at least one adherend adhered with a cured product obtained by curing the conductive resin adhesive according to one embodiment preferably includes an adherend having poorly conductive nickel as its outermost surface. In electronic components including an adherend having poorly conductive nickel as its outermost surface, it is more preferable that the adherend having poorly conductive nickel is bonded to a ceramic chip using a cured product obtained by curing the conductive resin adhesive according to one embodiment. The adherend having nickel as its outermost surface (adherend having nickel as its outermost surface) is not particularly limited, and may be an adherend made of nickel alone, but is preferably a nickel-plated adherend (adherend having nickel as its outermost surface). The nickel-plated adherend is not particularly limited, but examples thereof include SPCC (cold-rolled steel plate), stainless steel member, or copper member that has been subjected to electrolytic plating (e.g., electrolytic nickel-plated plate, etc.), SPCC (cold-rolled steel plate), stainless steel member, or copper member that has been subjected to electroless plating (e.g., electroless nickel-plated plate, etc.), etc. Specific examples of nickel-plated adherends include electric wires, printed circuit boards, etc.

[0101] The uses of the cured product according to the above embodiment are not particularly limited, but examples thereof include uses similar to those of the conductive resin adhesive described above.

[0102] Although the embodiments of the present invention have been described in detail, it is clear that this is for illustrative and exemplary purposes only and not for limitation, and that the scope of the present invention should be interpreted by the appended claims.

[0103] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following, unless otherwise specified, tests were carried out under an environment of a temperature of 25°C and a relative humidity of 55% RH.

[0104] Examples 1 to 4 and Comparative Examples 1 to 3 The following components were prepared to prepare a conductive resin adhesive, which will hereinafter also be referred to simply as a composition.

[0105] <Component (A): Epoxy resin> Epiclon (registered trademark) EXA-835LV (a mixture of bifunctional bisphenol A epoxy resin and bifunctional bisphenol F epoxy resin, mixed mass ratio 50:50, manufactured by DIC Corporation) ADEKA RESIN (registered trademark) EP-4000 (bifunctional polyoxyalkylene-modified bisphenol A epoxy resin, manufactured by ADEKA Corporation) jER (registered trademark) YX8000 (bifunctional hydrogenated bisphenol A epoxy resin, manufactured by Mitsubishi Chemical Corporation) <Component (B): Multifunctional vinyl ether having a cyclic structure> CHDVE (cyclohexanedimethanol divinyl ether, manufactured by Nippon Carbide Industries Co., Ltd.) <Component (B'): Vinyl ether other than component (B)> DEGDVE (diethylene glycol divinyl ether, manufactured by Nippon Carbide Industries Co., Ltd.) CHVE (cyclohexyl vinyl ether, manufactured by Nippon Carbide Industries Co., Ltd.) <Component (C): Conductive particles> M27 (crystalline silver particles, plate-shaped, no surface treatment, average particle size: 4.5 μm, specific surface area: 1.0 m ２ / g, manufactured by Tokusen Kogyo Co., Ltd.) <Component (D): Thermal Cationic Polymerization Initiator> K-PURE (registered trademark) CXC-1821 (a salt composed of tetrakis(pentafluorophenyl)borate anion and a quaternary ammonium cation, manufactured by King Industries) <Optional Components> CARDURA E10P (a monofunctional reactive diluent, neodecanoic acid glycidyl ester, manufactured by MOMENTIVE).

[0106] The compositions of Examples 1 to 4 and Comparative Examples 1 to 3 were produced as follows. Component (A), component (B) (or component (B')), and component (C) were weighed, and optional components were further weighed as needed. These components were stirred for 30 minutes using a planetary mixer. Component (D) was then weighed and added, and the mixture was stirred using a planetary mixer for an additional 30 minutes while being degassed under vacuum, yielding a conductive resin adhesive. All of the obtained conductive resin adhesives were liquid at 25°C. The detailed amounts prepared were as shown in Table 1. The amounts of each component and the total amount in Table 1 are all expressed in parts by mass.

[0107] <Conductivity Measurement> Five 5mm diameter holes were punched at 10mm intervals along the length of a 10mm wide, 100µm thick masking tape. The masking tape with the holes was attached to an electroless nickel-plated plate measuring 25mm wide, 100mm long, and 1.6mm thick. A composition was applied using a squeegee to the electroless nickel-plated plate with the holed masking tape. When applying the composition using the squeegee, care was taken to avoid introducing bubbles into the composition. Next, the masking tape with the holes was peeled off to obtain a test piece. The test piece was placed on a hot plate set to 130°C and left for 3 minutes, after which the test piece was removed from the hot plate. After the temperature of the test piece had cooled to 25°C, the needle electrodes of a dual display multimeter (DL-2050, manufactured by KENWOOD CORPORATION) were touched to adjacent cured compositions to measure resistance. The resistance of each of the four adjacent pairs of cured products was measured, and the average of the obtained resistance values ​​was recorded as "conductivity 130°C x 3 minutes (Ω)."

[0108] Furthermore, the test pieces after heating at 130°C for 3 minutes as described above were heated in a hot air drying oven at 80°C for 60 minutes. The test pieces were removed from the hot air drying oven, and after the temperature of the test pieces had dropped to 25°C, the needle electrodes of a dual display multimeter (DL-2050, manufactured by KENWOOD CORPORATION) were touched to adjacent cured compositions to measure their resistance, as in the test method described above. The resistance of each of the four pairs of adjacent cured compositions was measured, and the average of the obtained resistance values ​​was recorded as "conductivity 130°C x 3 minutes + 80°C x 60 minutes (Ω)."

[0109] In this evaluation, for both "Conductivity 130°C x 3 minutes (Ω)" and "Conductivity 130°C x 3 minutes + 80°C x 60 minutes (Ω)", the conductivity (resistance value) was evaluated as preferably 1.0Ω or less, more preferably 0.5Ω or less, and even more preferably 0.3Ω or less. In addition, the test result "Insulation" indicates that the resistance value exceeded the measurement limit of the dual display multimeter.

[0110] <Adhesion Strength Measurement> Masking tape was attached to an electroless nickel-plated plate measuring 1.6 mm thick x 25 mm wide x 100 mm long, so that the area to be coated with the composition was 5 mm wide x 50 μm thick. The composition was applied using a squeegee to form a uniform coating, and then the masking tape was peeled off. A 2φ (2 mm diameter) x 1 mm ceramic chip (material: alumina) was dropped vertically onto the coating from 1 cm above the coating, with the 2φ surface facing the adhesive surface, to prepare a test piece (n = 5: i.e., five test pieces were prepared). The test piece was placed on a hot plate set to 130 ° C. and left for 3 minutes, after which the test piece was removed from the hot plate. After the temperature of the test piece dropped to 25°C, a digital force gauge with contacts (FGP-20 manufactured by Nidek Drive Technology Co., Ltd.) was moved at 50 mm / min with the electroless nickel-plated plate fixed, and the tip was pressed with the contacts in a direction perpendicular to the long side of the test piece to measure the "maximum strength (N)". The "adhesion strength 130°C x 3 minutes (MPa)" was calculated by converting from the adhesion area and calculating the average value of n = 5 (i.e., the adhesion strength of each test piece was calculated from the "maximum strength (N)" converted from the adhesion area, and the average adhesion strength of the five test pieces was calculated to obtain the "adhesion strength 130°C x 3 minutes (MPa)").

[0111] Separately, test pieces were prepared by heating at 130 ° C. for 3 minutes in the same manner as above to cure the composition, and the prepared test pieces were heated in a hot air drying oven at 80 ° C. for 60 minutes. The test pieces were removed from the hot air drying oven, and after the temperature of the test pieces had dropped to 25 ° C., the same test method as above was used. With the electroless nickel-plated plate fixed, a digital force gauge with contacts (FGP-20 manufactured by Nidek Drive Technology Co., Ltd.) was moved at 50 mm / min, and the tip was pressed with the contacts in a direction perpendicular to the long side of the test piece to measure the "maximum strength (N)". The average value of n = 5 was calculated from the adhesive area and given as "adhesive strength 130 ° C. × 3 min + 80 ° C. × 60 min (MPa)" (i.e., the adhesive strength of each test piece was calculated from the adhesive area, and the average adhesive strength of the five test pieces was calculated and given as "adhesive strength 130 ° C. × 3 min + 80 ° C. × 60 min (MPa)").

[0112] In this evaluation, in order to prevent the adherend from falling off, it is preferable that both the "adhesive strength 130°C x 3 minutes (MPa)" and the "adhesive strength 130°C x 3 minutes + 80°C x 60 minutes (MPa)" are 10 MPa or more.

[0113] The results of the electrical conductivity measurement and adhesive strength measurement are shown in Table 1. Note that blank cells in Table 1 indicate that the component was not contained.

[0114]

[0115] Examples 1 to 4 are compositions containing components (A) to (D), respectively. Although the structures of the component (A) differ, all were confirmed to have excellent conductivity and adhesive strength of the cured products. In particular, Examples 1 and 2, which contained only a bisphenol-type epoxy resin as the component (A), were confirmed to have excellent conductivity of the cured products. Furthermore, Example 3, which contained only a hydrogenated bisphenol A-type epoxy resin (hydrogenated bisphenol A-type epoxy resin) as the component (A), was confirmed to have excellent adhesive strength of the cured products. Example 4, which contained a bisphenol-type epoxy resin and a hydrogenated bisphenol-type epoxy resin as the component (A), produced cured products with a good balance of conductivity and adhesive strength. All of these examples demonstrate that the cured products exhibit sufficient conductivity and adhesive strength, even when cured for a short time, such as 3 minutes at 130°C.

[0116] On the other hand, in Comparative Examples 1 and 2, which contain DEGDVE and CHVE as component (B') instead of component (B), respectively, it was confirmed that the cured product had poor electrical conductivity and poor adhesive strength. Comparative Example 3, which does not contain component (B) or (B') but contains the optional component E10P instead, resulted in poor curability, poor electrical conductivity of the cured product, and poor adhesive strength of the cured product.

[0117] The conductive resin adhesive according to one embodiment of the present invention exhibits excellent conductivity and adhesive strength in the cured product when cured in a short time. Therefore, the conductive resin adhesive according to one embodiment of the present invention and the cured product according to another embodiment of the present invention are useful for electrical conductivity and adhesion applications for the miniaturized electrical and electronic components of recent years, and can reduce the resistance of the cured product, particularly to metals that tend to have poor conductivity, such as nickel. Because of these properties, the conductive resin adhesive according to one embodiment of the present invention and the cured product according to another embodiment of the present invention can be used in the assembly of various electrical and electronic components, and have the potential to be deployed in a wide range of applications.

[0118] This application is based on Japanese Patent Application No. 2023-98857, filed on June 16, 2023, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A conductive resin adhesive comprising the following components (A) to (D): component (A): an epoxy resin having two or more glycidyl groups; component (B): a multifunctional vinyl ether having a cyclic structure (excluding epoxy resins having two or more glycidyl groups); component (C): conductive particles; and component (D): a thermal cationic polymerization initiator.

2. The conductive resin adhesive according to claim 1, wherein component (A) comprises a bisphenol type epoxy resin.

3. The conductive resin adhesive according to claim 1 or 2, wherein component (A) comprises a hydrogenated bisphenol type epoxy resin.

4. The conductive resin adhesive according to claim 1 or 2, wherein the component (B) is a polyfunctional vinyl ether having an alicyclic structure.

5. The conductive resin adhesive according to claim 1 or 2, wherein component (C) contains crystalline conductive particles.

6. The conductive resin adhesive according to claim 1 or 2, wherein the cationic species of component (D) is a quaternary ammonium cation.

7. The conductive resin adhesive according to claim 1 or 2, wherein the component (B) is cyclohexanedimethanol divinyl ether.

8. The conductive resin adhesive according to claim 1 or 2, in which the electrical conductivity of the cured product cured by heating at 130° C. for 3 minutes is 0.3 Ω or less.

9. A cured product obtained by curing the conductive resin adhesive according to claim 1 or 2.