Electrically conductive resin composition and cured product thereof

Abstract

Provided is an electrically conductive resin composition that can be cured at a low temperature (for example, 80°C) and gives a cured product having good electrical conductivity even after keeping (storing) the electrically conductive resin composition for a long time (for example, 48 hours) at 25°C (normal temperature).　A conductive resin composition according to the present invention contains the following components (A) to (D). Component (A): at least one of the following components (A1) and (A2); component (A1): a urethane (meth)acrylate having two or more (meth)acryloyl groups per molecule, component (A2): an epoxy (meth)acrylate having two or more (meth)acryloyl groups per molecule (excluding the component (A1), component (B): a monofunctional (meth)acrylate having an ether skeleton, component (C): electrically conductive particles, and component (D): a thermal radical generator

Description

Conductive resin composition and cured product thereof

[0001] The present invention relates to an electrically conductive resin composition and a cured product thereof.

[0002] Conventionally, conductive resin compositions have been used for fixing and grounding electrical and electronic components such as smartphones and electronic mobile devices. In recent years, as electronic components have become smaller and lighter, plastics are often used as materials for constituting these electronic components. Therefore, the conductive resin compositions used therein are required to be curable at low temperatures such as 80°C. Examples of conductive resin compositions that can be cured at low temperatures include the low-temperature curing conductive resin composition disclosed in International Publication No. 2020 / 090757 (corresponding to the specification of U.S. Patent Application Publication No. 2021 / 0380850).

[0003] However, because conductive resin compositions that cure at low temperatures such as 80° C. are highly reactive, their properties gradually change even while they are stored (kept) at 25° C. (room temperature).As a result, the conductivity of a cured product obtained from a conductive resin composition stored at 25° C. for a long period of time, such as 24 to 48 hours, may change (specifically, decrease).

[0004] The present invention has been made in view of the above circumstances, and aims to provide a conductive resin composition that can be cured at a low temperature (e.g., 80°C) and that gives a cured product with good conductivity even after the conductive resin composition is stored (kept) for a long period of time (e.g., 48 hours) at 25°C (room temperature). Another aim of the present invention is to provide a cured product using the conductive resin composition.

[0005] As a result of intensive research to achieve the above object, the present inventors discovered a method for obtaining a conductive resin composition that can be cured at a low temperature (e.g., 80°C) and that can give a cured product with excellent conductivity even after the conductive resin composition has been stored (kept) at 25°C for a long period of time (e.g., 48 hours), and have thereby completed the present invention.

[0006] The gist of the present invention is described below: [1] A conductive resin composition comprising the following components (A) to (D): Component (A): at least one of the following components (A1) and (A2): Component (A1): a urethane (meth)acrylate having two or more (meth)acryloyl groups in one molecule; Component (A2): an epoxy (meth)acrylate having two or more (meth)acryloyl groups in one molecule (excluding the component (A1)); Component (B): a monofunctional (meth)acrylate having an ether skeleton; Component (C): conductive particles; and Component (D): a thermal radical generator. [2] The conductive resin composition according to [1], wherein the component (A1) is a urethane (meth)acrylate having two or more (meth)acryloyl groups and a polyether skeleton in one molecule. [3] The conductive resin composition according to [1] or [2], wherein the component (A) comprises the component (A1) and the component (A2), wherein the component (A1) is a urethane (meth)acrylate having two or more (meth)acryloyl groups and a polyether skeleton in one molecule, and the component (A2) is a bisphenol-type epoxy (meth)acrylate having two or more (meth)acryloyl groups in one molecule. [4] The conductive resin composition according to any one of [1] to [3], wherein the component (B) is at least one of a monofunctional (meth)acrylate having a skeleton derived from polypropylene glycol and a monofunctional (meth)acrylate having a phenoxy group and a polyether skeleton. [5] The conductive resin composition according to any one of [1] to [4], wherein the component (B) is contained in an amount of 20 to 150 parts by mass per 100 parts by mass of the component (A). [6] The conductive resin composition according to any one of [1] to [5], wherein the component (C) contains silver particles having an average particle size of 3 to 30 μm and silver particles having an average particle size of 0.1 μm or more and less than 3 μm. [7] The conductive resin composition according to any one of [1] to [6], further containing, as component (E), a polyfunctional (meth)acrylate having two or more (meth)acryloyl groups in one molecule (excluding the component (A)). [8] A cured product obtained by curing the conductive resin composition according to any one of [1] to [7]. [9] A method for producing a conductive resin composition, comprising mixing the following components (A) to (D):Component (A): at least one of the following component (A1) and / or component (A2): Component (A1): a urethane (meth)acrylate having two or more (meth)acryloyl groups in one molecule; Component (A2): an epoxy (meth)acrylate having two or more (meth)acryloyl groups in one molecule (excluding component (A1)); Component (B): a monofunctional (meth)acrylate having an ether skeleton; Component (C): conductive particles; and Component (D): a thermal radical generator.

[10] The method for producing a conductive resin composition according to [9], wherein the component (A1) is a urethane (meth)acrylate having two or more (meth)acryloyl groups and a polyether skeleton in one molecule.

[11] The method for producing a conductive resin composition according to [9] or

[10] , wherein the component (A) comprises the component (A1) and the component (A2), wherein the component (A1) is a urethane (meth)acrylate having two or more (meth)acryloyl groups and a polyether skeleton in one molecule, and the component (A2) is a bisphenol-type epoxy (meth)acrylate having two or more (meth)acryloyl groups in one molecule.

[12] The method for producing a conductive resin composition according to any of [9] to

[11] , wherein the component (B) is at least one of a monofunctional (meth)acrylate having a skeleton derived from polypropylene glycol and a monofunctional (meth)acrylate having a phenoxy group and a polyether skeleton.

[13] The method for producing a conductive resin composition according to any of [9] to

[12] , wherein the component (B) is contained in an amount of 20 to 150 parts by mass per 100 parts by mass of the component (A).

[14] The method for producing a conductive resin composition according to any one of [9] to

[13] , wherein the component (C) contains silver particles having an average particle size of 3 to 30 μm and silver particles having an average particle size of 0.1 μm or more and less than 3 μm.

[15] The method for producing a conductive resin composition according to any one of [9] to

[14] , further comprising mixing, as component (E), a polyfunctional (meth)acrylate having two or more (meth)acryloyl groups in one molecule (excluding the component (A)).

[0007] 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. Furthermore, the embodiments described in this specification can be arbitrarily combined to form other embodiments.

[0008] Throughout this specification, singular expressions should be understood to include the plural concept unless otherwise specified. Therefore, singular articles (e.g., "a," "an," "the," etc. in English) should be understood to include the plural concept unless otherwise specified. Furthermore, terms used in this specification should be understood to be used in the sense commonly used in the art unless otherwise specified. Therefore, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification (including definitions) will prevail.

[0009] In this specification, "X to Y" is used to mean that the numerical values ​​(X and Y) written before and after it are included as the lower and upper limits, respectively, and means "X or more and Y or less." In addition, in this specification, the term "(meth)acryloyl" includes both acryloyl and methacryloyl. Therefore, for example, the term "(meth)acryloyl group" refers to an acryloyl group (H ２ C=CH-C(=O)-) and methacryloyl groups (H ２ C=C(CH ３ )-C(=O)-). Similarly, the term "(meth)acrylate" includes both acrylate and methacrylate, and the term "(meth)acrylic" includes both acrylic and methacrylic. Furthermore, "A and / or B" means that A and B are each included, as well as any combination thereof.

[0010] Furthermore, in this specification, when a certain structure or structural unit is defined as being "derived from" or "derived from" a certain monomer, it means that the structure or structural unit is a structural unit that is generated by the reaction of reactive groups possessed by the corresponding monomer and / or is generated by the cleavage of a polymerizable unsaturated double bond (ethylenically unsaturated group) possessed by the corresponding monomer.

[0011] Unless otherwise specified, concentrations and percentages represent mass concentrations and mass percentages, respectively, and ratios represent mass ratios unless otherwise specified. Unless otherwise specified, operations and measurements of physical properties are performed under conditions of 25°C and a relative humidity of 40 to 55% RH.

[0012] According to one embodiment of the present invention, there is provided a conductive resin composition comprising the following components (A) to (D): Component (A): at least one of the following components (A1) and (A2); Component (A1): a urethane (meth)acrylate having two or more (meth)acryloyl groups in one molecule; Component (A2): an epoxy (meth)acrylate having two or more (meth)acryloyl groups in one molecule (excluding the above-mentioned component (A1)); Component (B): a monofunctional (meth)acrylate having an ether skeleton; Component (C): conductive particles; and Component (D): a thermal radical generator.

[0013] With this configuration, it is possible to provide a conductive resin composition that can be cured at low temperatures (e.g., 80°C) and that gives a cured product with good conductivity even after the conductive resin composition is stored (kept) for a long period of time (e.g., 48 hours) at 25°C (room temperature). Furthermore, the cured product obtained by curing the conductive resin composition after storage as described above has a smaller rate of change in conductivity than the cured product obtained by curing the conductive resin composition before storage.

[0014] In this specification, the conductive resin composition having the above-described structure is also simply referred to as the "conductive resin composition according to the present invention" or "conductive resin composition." In this specification, the component (A) is also simply referred to as the "component (A) according to the present invention" or "component (A)." In this specification, the component (A1) is also simply referred to as the "component (A1) according to the present invention" or "component (A1)." In this specification, the component (A2) is also simply referred to as the "component (A2) according to the present invention" or "component (A2)." In this specification, the component (B) is also simply referred to as the "component (B) according to the present invention" or "component (B)." In this specification, the component (C) is also simply referred to as the "component (C) according to the present invention" or "component (C)." In this specification, the component (D) is also simply referred to as the "component (D) according to the present invention" or "component (D)." Furthermore, in this specification, the component (E) described in detail below will also be referred to simply as "the component (E) according to the present invention" or "component (E)".

[0015] Hereinafter, an embodiment of the present invention will be described.

[0016] [Conductive Resin Composition] <Component (A)> The component (A) used in the present invention is the following component (A1) and / or component (A2). That is, the component (A) according to the present invention is at least one of the following components (A1) and (A2): component (A1): a urethane (meth)acrylate having two or more (meth)acryloyl groups in one molecule; component (A2): an epoxy (meth)acrylate having two or more (meth)acryloyl groups in one molecule (excluding the above component (A1)).

[0017] That is, the conductive resin composition according to the present invention contains, as component (A), at least one (meth)acrylate having two or more (meth)acryloyl groups in one molecule (polyfunctional (meth)acrylate). Here, the polyfunctional (meth)acrylate is a compound having two or more (meth)acryloyl groups in one molecule. The (meth)acryloyl group can be contained in the polyfunctional (meth)acrylate in the form of a (meth)acryloyloxy group.

[0018] The number of (meth)acryloyl groups contained in one molecule of the polyfunctional (meth)acrylate as component (A) (component (A1) and component (A2)) is not particularly limited as long as it is 2 or more, but is, for example, 2 to 6, preferably 2 to 4, more preferably 2 to 3, and particularly preferably 2, per molecule. Furthermore, from the viewpoint of improving curability, the (meth)acryloyl groups contained in component (A) (component (A1) and component (A2)) are preferably acryloyl groups.

[0019] The component (A) may contain either the component (A1) or the component (A2), but preferably contains both from the viewpoint of improving the electrical conductivity and adhesive strength of the resulting cured product in a well-balanced manner. That is, the component (A) preferably contains the above-mentioned component (A1) and component (A2) (the component (A) is the above-mentioned component (A1) and component (A2)).

[0020] The mass ratio (content ratio) of the (A1) component to the (A2) component ((A1) component:(A2) component) is preferably 10:90 to 90:10, more preferably 25:75 to 75:25, even more preferably 30:70 to 60:40, and most preferably 30:70 to 50:50. When the mass ratio (content ratio) of the (A1) component to the (A2) component is within the above range, a cured product with superior conductivity and adhesive strength can be obtained. The (A1) component and the (A2) component may each be used alone, or two or more types may be used in combination. When two or more types of each component are used in combination, the contents of the (A1) component and the (A2) component refer to the combined amounts.

[0021] The above-mentioned component (A1) is a urethane (meth)acrylate having two or more (meth)acryloyl groups in one molecule. Here, "urethane (meth)acrylate" refers to an ester compound having a urethane bond and a (meth)acryloyl group. That is, a urethane (meth)acrylate is a (meth)acrylic acid ester having a urethane bond. The urethane bond can be formed by reacting an isocyanate group with a hydroxy group. In the urethane (meth)acrylate as component (A1), the number of urethane bonds per molecule may be one or more.

[0022] The urethane (meth)acrylate as component (A1) may further contain a structure other than a urethane bond and a (meth)acryloyl group, for example, at least one selected from the group consisting of a polyester skeleton, a polycaprolactone skeleton, a polycarbonate skeleton, and a polyether skeleton. One or more of these skeletons may be contained in one molecule. From the viewpoint of further improving the desired effects, it is particularly preferred that component (A1) have a polyether skeleton. In this specification, the term "polyether skeleton" refers to a skeleton having two or more oxyalkylene structures as repeating units, such as a skeleton having repeating units derived from an alkylene oxide, such as polyethylene oxide, polypropylene oxide, or polybutylene glycol.

[0023] From the viewpoint of further improving the intended effect, the component (A1) is preferably a urethane (meth)acrylate having two or more (meth)acryloyl groups and a polyether skeleton in one molecule, and more preferably a urethane acrylate having two or more acryloyl groups and a polyether skeleton in one molecule. Furthermore, as a preferred embodiment, the component (A1) may be a urethane acrylate having two to three acryloyl groups and a polyether skeleton in one molecule. Furthermore, as another preferred embodiment, the component (A1) may be a urethane acrylate having two acryloyl groups and a polyether skeleton in one molecule.

[0024] The urethane (meth)acrylate used as component (A1) may be either a synthetic product or a commercially available product. Examples of methods for synthesizing component (A1) include a method in which a urethane bond is formed by reacting a polyol compound with a polyisocyanate compound, and then adding a compound having a hydroxyl group and a (meth)acryloyl group in the molecule or (meth)acrylic acid to the unreacted isocyanate group, and a method in which a compound having a hydroxyl group and a (meth)acryloyl group in the molecule or (meth)acrylic acid is added to a polyisocyanate compound to form a urethane bond, but the method is not limited to these methods.

[0025] Examples of the polyol compound include polyether polyol, polyester polyol, caprolactone diol, bisphenol polyol, polyisoprene polyol, hydrogenated polyisoprene polyol, polybutadiene polyol, hydrogenated polybutadiene polyol, castor oil polyol, and polycarbonate diol.

[0026] Examples of the polyisocyanate compound include, but are not limited to, aliphatic polyisocyanate compounds, alicyclic polyisocyanate compounds, aromatic polyisocyanate compounds, etc. Examples of the aliphatic polyisocyanate compound include tetramethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, etc. Examples of the alicyclic polyisocyanate compound include 1-methylcyclohexane-2,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, etc. Furthermore, examples of the aromatic polyisocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, polyphenylene polymethylene polyisocyanate, 1,5-naphthylene diisocyanate, 1,4-naphthylene diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, o-xylylene diisocyanate, and m-xylylene diisocyanate.

[0027] Examples of the compound having a hydroxyl group and a (meth)acryloyl group include, but are not limited to, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, mono(meth)acrylates of dihydric alcohols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and polyethylene glycol, and mono(meth)acrylates or di(meth)acrylates of trihydric alcohols such as trimethylolethane, trimethylolpropane, and glycerin.

[0028] The weight-average molecular weight (Mw) of component (A1) is preferably 500 to 50,000, more preferably 500 to 10,000, particularly preferably 1,000 to 5,000, and most preferably 1,000 to 3,000. A weight-average molecular weight of 500 or more results in a cured product with excellent adhesive strength, while a weight-average molecular weight of 50,000 or less results in a cured product with good electrical conductivity. Here, the weight-average molecular weight is a value measured by gel permeation chromatography (GPC) using polystyrene as a standard substance.

[0029] The urethane (meth)acrylate as component (A1) is preferably a urethane (meth)acrylate oligomer in order to improve the desired effects. In this specification, the term "oligomer" refers to a polymer in which two to several tens of monomer units (including monomer units other than (meth)acrylate monomers) are repeated, and which has a weight-average molecular weight of 500 or more.

[0030] Commercially available products of the component (A1) include, but are not limited to, NK Oligo (registered trademark) UA-4200, UA-160™, UA-290™, and UA-W2A (manufactured by Shin-Nakamura Chemical Co., Ltd.), ART RESIN (registered trademark) UN-6200, UN-6207, UN-6304, UN-6306, and UN-6060S (manufactured by Negami Chemical Industrial Co., Ltd.), and EBECRYL (registered trademark) 230, 270, 4491, 8307, and 8402 (manufactured by Daicel-Allnex Corporation). These may be used alone, or two or more types may be used in combination.

[0031] The component (A2) is an epoxy (meth)acrylate having two or more (meth)acryloyl groups in one molecule (excluding the component (A1)). In one embodiment, the "epoxy (meth)acrylate" is preferably a compound having a (meth)acryloyl group obtained by reacting an epoxy compound with a compound having a (meth)acryloyl group. Specifically, it is preferably a compound obtained by reacting an epoxy group (which may be contained in the form of a glycidyl group) contained in an epoxy compound with (meth)acrylic acid. That is, the epoxy (meth)acrylate preferably has a structure (A) represented by the following formula (A):

[0032]

[0033] In the above formula (A), * represents a binding site, and R ２ represents a hydrogen atom or a methyl group.

[0034] The number of the above structure (A) contained in the epoxy (meth)acrylate as component (A2) in one molecule is, for example, 2 to 6, preferably 2 to 4, more preferably 2 to 3, and particularly preferably 2. From the viewpoint of improving curability, in the above formula (A), R ２ is preferably a hydrogen atom.

[0035] Note that component (A2) does not include those included in component (A1). Therefore, for example, an epoxy (meth)acrylate having two or more (meth)acryloyl groups and urethane bonds in one molecule would be classified as component (A1).

[0036] The epoxy (meth)acrylate as component (A2) may further contain a structure other than a (meth)acryloyl group (for example, the above structure (A)), and may have, for example, a structure derived from at least one selected from the group consisting of bisphenol A, bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, and phenol novolac. One type of these structures may be contained in one molecule, or two or more types may be contained in combination. Among these, from the viewpoint of excellent adhesive strength, it is preferable that component (A2) has a structure derived from bisphenol (is a bisphenol-type epoxy (meth)acrylate). In one embodiment, the component (A2) preferably has a structure derived from at least one selected from the group consisting of bisphenol A, bisphenol F, hydrogenated bisphenol A, and hydrogenated bisphenol F, more preferably has a structure derived from bisphenol A and / or bisphenol F (i.e., bisphenol A-type epoxy (meth)acrylate and / or bisphenol F-type epoxy (meth)acrylate), and particularly preferably has a structure derived from bisphenol A (i.e., bisphenol A-type epoxy (meth)acrylate). Furthermore, in each of the above embodiments, the epoxy (meth)acrylate is preferably an epoxy acrylate.

[0037] The epoxy (meth)acrylate used as component (A2) may be either a synthetic product or a commercially available product. Examples of methods for synthesizing component (A2) include, but are not limited to, ring-opening polymerization of (meth)acrylic acid or the like with a glycidyl group contained in a glycidyl ether compound. Furthermore, in such synthesis methods, unreacted glycidyl groups may remain in the molecule. The main chain of the glycidyl ether compound may have a variety of skeletons, including bisphenol A type (bisphenol A type epoxy resin), bisphenol F type (bisphenol F type epoxy resin), hydrogenated bisphenol A type (hydrogenated bisphenol A type epoxy resin), hydrogenated bisphenol F type (hydrogenated bisphenol F type epoxy resin), and phenol novolac type (phenol novolac resin). However, bisphenol type is preferred, and bisphenol A type is even more preferred, due to its excellent adhesive strength. These may be used alone or in combination of two or more types.

[0038] Furthermore, bisphenol-type epoxy (meth)acrylates, which are preferred forms of component (A2), can also be obtained by reacting a bisphenol compound with epichlorohydrin and (meth)acrylic acid. The bisphenol compounds used in this case are the same as those for the above-mentioned epoxy resins, and these can be used alone or in combination of two or more.

[0039] The weight-average molecular weight (Mw) of component (A2) is preferably 200 to 5,000, more preferably 250 to 4,000, particularly preferably 300 to 3,000, and most preferably 1,000 to 2,500. A weight-average molecular weight of 200 or more results in a cured product with excellent adhesive strength, while a weight-average molecular weight of 5,000 or less results in a cured product with good electrical conductivity. The weight-average molecular weight is measured by gel permeation chromatography (GPC) using polystyrene as the standard. The epoxy (meth)acrylate used as component (A2) is preferably an epoxy (meth)acrylate oligomer, as this enhances the desired effects.

[0040] Commercially available products of the component (A2) include, but are not limited to, EBECRYL (registered trademark) 3700, 3708 (manufactured by Daicel Allnex Corporation), Epoxy Ester 3000A, 3002A (manufactured by Kyoeisha Chemical Co., Ltd.), BAEA-100, BAEM-100, BEEA-50, PNEM-50 (manufactured by KSM Corporation), NK Oligo (registered trademark) EA-1010N, WA-1010LC, EA-1020LC3, etc. These may be used alone or in combination of two or more types.

[0041] <<Preferred Embodiment>> In one embodiment, the component (A) includes both the component (A1) and the component (A2) (i.e., both the component (A1) and the component (A2)). In this embodiment, preferably, the component (A1) is a urethane (meth)acrylate having two or more (meth)acryloyl groups and a polyether skeleton in one molecule, and the component (A2) is a bisphenol-type epoxy (meth)acrylate having two or more (meth)acryloyl groups in one molecule.

[0042] In the above embodiment, it is more preferable that the component (A1) is a urethane (meth)acrylate having two to three (meth)acryloyl groups and a polyether skeleton in one molecule, and the component (A2) is a bisphenol-type epoxy (meth)acrylate having two or more (meth)acryloyl groups in one molecule.

[0043] Furthermore, in the above embodiment, it is more preferable that the component (A1) is a urethane acrylate having two to three acryloyl groups and a polyether skeleton in one molecule, and the component (A2) is a bisphenol A epoxy acrylate and / or bisphenol F epoxy acrylate having two to three (meth)acryloyl groups in one molecule.

[0044] Furthermore, in the above-described embodiment, it is particularly preferable that the component (A1) is a urethane acrylate having two acryloyl groups and a polyether skeleton in one molecule, and the component (A2) is a bisphenol A epoxy acrylate having two (meth)acryloyl groups in one molecule.

[0045] Furthermore, in each of the above-described embodiments, the mass ratio of the component (A1) to the component (A2) is preferably any of the above-described preferred mass ratios. Also, in each of the above-described embodiments, the (meth)acryloyl group contained in the component (A2) is preferably contained in the form of the above-described structure (A).

[0046] <Component (B)> The component (B) used in the present invention is a monofunctional (meth)acrylate having an ether skeleton. In this specification, the term "ether skeleton" refers to a structure (-C-O-C-) in which an oxygen atom connects two or more carbon atoms in a molecule. Furthermore, a "monofunctional (meth)acrylate" refers to a compound having one (meth)acryloyl group in one molecule. The (meth)acryloyl group may be contained in the monofunctional (meth)acrylate in the form of a (meth)acryloyloxy group. However, when an ether bond (-C-O-C-) is formed by a (meth)acryloyloxy group contained in a monofunctional (meth)acrylate, this moiety does not fall under the category of "ether skeleton" as used herein, and therefore, a (meth)acrylate compound having only such an ether bond does not fall under the category of "monofunctional (meth)acrylate having an ether skeleton." In other words, the "ether skeleton" as used herein refers to one formed in the molecule of the component (B) separately from the (meth)acryloyloxy group. Therefore, for example, alkyl (meth)acrylates such as isobornyl (meth)acrylate and n-octyl (meth)acrylate, and hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are not included in the component (B) of the present invention. Furthermore, component (B) is a monofunctional (meth)acrylate that does not have an acidic group such as a carboxyl group, a phosphoric acid group, or a phosphonic acid group. Such monofunctional (meth)acrylates that have an acidic group are classified as optional components, which will be described later.

[0047] The conductive resin composition according to the present invention contains a monofunctional (meth)acrylate having an ether skeleton (component (B)), and thus can form a cured product with good conductivity even after the conductive resin composition has been stored (kept) at 25°C (room temperature) for a long period of time (for example, 48 hours).

[0048] The monofunctional (meth)acrylate as component (B) is not particularly limited as long as it has the above-mentioned ether skeleton.

[0049] In one embodiment, the ether skeleton contained in component (B) may be derived from an aliphatic polyhydric alcohol such as ethylene glycol, propylene glycol, or tetramethylene ether glycol, but is not limited thereto. That is, in one embodiment, component (B) may have structural units derived from the above-mentioned aliphatic polyhydric alcohols. In terms of excellent conductivity, the ether skeleton contained in component (B) is preferably derived from ethylene glycol and / or propylene glycol, and more preferably derived from propylene glycol. That is, component (B) preferably has structural units derived from ethylene glycol and / or propylene glycol, and even more preferably has structural units derived from propylene glycol. These structural units may be contained alone or in multiple units in one molecule. The number of structural units derived from an aliphatic polyhydric alcohol contained in component (B) is preferably 1 to 10, more preferably 1 to 7, and most preferably 2 to 5. When the number of repetitions is within the above range, a conductive resin composition with excellent workability and conductivity can be obtained.

[0050] Furthermore, component (B) may contain, in addition to the ether skeleton, a skeleton (structure) other than the ether skeleton. Specific examples include aliphatic hydrocarbon groups, aromatic hydrocarbon groups, ester groups, carbonate groups, and urethane bonds. However, because a cured product with excellent conductivity can be obtained even after storage at 25°C, component (B) preferably contains an ether skeleton and at least one of an aliphatic hydrocarbon group and an aromatic hydrocarbon group. Examples of aliphatic hydrocarbon groups include linear or branched alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, and decyl; linear or branched alkenyl groups such as vinyl and allyl; and alkynyl groups such as ethynyl and propynyl. Of these, linear or branched alkyl groups are preferred. Examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, and an anthracenyl group.

[0051] In one embodiment, component (B) can be a (meth)acrylate monomer represented by the following formula (B):

[0052]

[0053] In the above formula (B), R ３ represents a hydrogen atom or a methyl group; R ４ represents a linear or branched alkylene group having 1 to 5 carbon atoms; R ５ represents a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms which may have a substituent, or an aryl group having 6 to 10 carbon atoms which may have a substituent, and n represents the average number of moles of oxyalkylene groups added and is 1 to 10.

[0054] In the above formula (B), R ３ is a hydrogen atom or a methyl group, and preferably, R ３ is a hydrogen atom.

[0055] In the above formula (B), R ４is a linear or branched alkylene group having 1 to 5 carbon atoms. Examples of such alkylene groups include a methylene group, an ethylene group, a trimethylene group, and a propylene group (—CH ２ -CH(CH ３ ) -, -CH(CH ３ )-CH ２ -), n-butylene group, 1-methylpropylene group (-CH ２ -CH ２ -CH(CH ３ )-), 2-methylpropylene group (—CH ２ -CH(CH ３ )-CH ２ -), dimethylethylene group (-CH ２ -C(CH ３ ) ２ -), ethylethylene group (-CH ２ -CH(CH ２ CH ３ ) -, -CH(CH ２ CH ３ )-CH ２ -) and the like. ４ is preferably a linear or branched alkylene group having 1 to 3 carbon atoms, and more preferably a linear or branched alkylene group having 2 or 3 carbon atoms. ４ When there are multiple -OR (n is 2 or more), each -OR ４ - may be the same or different.

[0056] In the above formula (B), R ５is a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms which may have a substituent, or an aryl group having 6 to 10 carbon atoms which may have a substituent. Here, unless otherwise specified, "optionally substituted" means that the group may be substituted with at least one or more groups selected from alkyl groups, cycloalkyl groups, alkoxy groups, cycloalkoxy groups, alkenyl groups, amino groups, aryl groups, aryloxy groups, and hydroxyl groups (-OH). Note that when a group is substituted, the form of substitution that would be included in the definition before the substituted structure is further substituted is excluded. For example, when the substituent is an alkyl group, this alkyl group as a substituent is not further substituted with an alkyl group. Furthermore, the above carbon number does not include the carbon atoms contained in the substituent.

[0057] Examples of linear or branched alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, 1,2-dimethylpropyl, n-hexyl, isohexyl, 1,3-dimethylbutyl, 1-isopropylpropyl, 1,2-dimethylbutyl, n-heptyl, 1,4-dimethylpentyl, 3-ethylpentyl, 2-methyl-1-isopropylpropyl, 1-ethyl-3-methylbutyl, n-octyl, and 2-ethylhexyl groups. Examples of aryl groups include phenyl and naphthyl groups.

[0058] R ５ is preferably a hydrogen atom, an unsubstituted linear or branched alkyl group having 1 to 8 carbon atoms, or an unsubstituted aryl group having 6 to 10 carbon atoms, more preferably an unsubstituted linear or branched alkyl group having 1 to 3 carbon atoms or a phenyl group, even more preferably a methyl group, an ethyl group, or a phenyl group, and particularly preferably a methyl group or a phenyl group.

[0059] In the above formula (B), n represents an alkylene oxide (—OR ４n represents the average number of moles of R ５ When is a hydrogen atom, n is 2 or more.

[0060] Furthermore, the (meth)acrylate monomer as the component (B) is a compound represented by the formula (B) above, wherein R ３ ~R ５ and n are preferably combinations of any of the above preferred embodiments.

[0061] Examples of the component (B) include, but are not limited to, polyethylene glycol mono(meth)acrylate, methoxypolyethylene glycol (meth)acrylate, ethoxypolyethylene glycol (meth)acrylate, butoxypolyethylene glycol (meth)acrylate, phenoxyethylene glycol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, polypropylene glycol mono(meth)acrylate, methoxydipropylene glycol (meth)acrylate, methoxytripropylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, ethoxypolypropylene glycol (meth)acrylate, butoxypolypropylene glycol (meth)acrylate, phenoxypolypropylene glycol (meth)acrylate, nonylphenoxypolypropylene glycol (meth)acrylate, polyethylene glycol polypropylene glycol mono(meth)acrylate, and polyethylene glycol polybutylene glycol mono(meth)acrylate. These may be used alone or in combination of two or more.The component (B) is preferably at least one selected from the group consisting of methoxypolyethylene glycol (meth)acrylate, phenoxyethylene glycol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, methoxytripropylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; the component (B) is more preferably at least one selected from the group consisting of phenoxyethylene glycol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, methoxytripropylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; and particularly preferably at least one selected from the group consisting of phenoxydiethylene glycol (meth)acrylate and methoxytripropylene glycol (meth)acrylate.

[0062] In order to obtain a cured product with excellent conductivity even after storage at 25°C, the (B) component preferably has a hydroxyl group (excluding acidic groups such as carboxyl groups and phenol groups), an alkoxy group, or an aromatic group at a terminal other than the (meth)acryloyl group. In one embodiment, the (B) component is more preferably at least one of a monofunctional (meth)acrylate having a skeleton derived from polypropylene glycol and a monofunctional (meth)acrylate having a phenoxy group and a polyether skeleton. That is, the (B) component is more preferably at least one of a monofunctional (meth)acrylate having two or more structural units derived from propylene glycol and a monofunctional (meth)acrylate having a phenoxy group and a polyether skeleton.

[0063] The content of the (B) component is preferably 10 to 200 parts by mass, more preferably 20 to 150 parts by mass, particularly preferably 50 to 100 parts by mass, and most preferably 60 to 80 parts by mass, per 100 parts by mass of the (A) component. When the (B) component content is 10 parts by mass or more, a conductive resin composition with excellent workability and conductivity can be obtained. Furthermore, when the (B) component content is 200 parts by mass or less, a conductive resin composition with excellent adhesive strength can be obtained. When two or more (B) components are used in combination, the content of the (B) component refers to the total amount.

[0064] <Component (C)> The component (C) used in the present invention is a conductive particle. The material and shape of the component (C) are not limited as long as it exhibits conductivity. For example, metal particles composed of at least one metal selected from the group consisting of gold, silver, copper, nickel, palladium, platinum, tin, bismuth, etc.; alloy particles composed of a combination of two or more metals selected from the above; particles coated on the surface with a coating layer of the above metal (particles having a coating layer composed of at least one metal selected from the above). These may be used alone or in combination of two or more. From the standpoints of conductivity and cost, the component (C) is preferably silver particles or particles coated on the surface with a coating layer of silver, more preferably silver particles. The shape of the component (C) may be spherical, irregular, flaky, filamentary (needle), or dendritic, but flaky is preferred due to its excellent conductivity. In this specification, the term "flake-like" means that the equivalent circle diameter of the surface (flat surface) with the largest projected area is greater than the maximum length (thickness) in the direction perpendicular to this surface, and is also referred to as scale-like, plate-like, thin flake-like, plate-like, flat, sheet-like, etc. The conductive particles may be used alone or in combination of two or more types.

[0065] Furthermore, component (C) may be surface-treated with a lubricant. Saturated and / or unsaturated fatty acids can be used as the lubricant. Examples of lubricants include 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. In order to achieve excellent adhesive strength and electrical conductivity in the cured product obtained by curing at low temperatures, the surface of component (C) is preferably untreated or treated with stearic acid and / or oleic acid, and more preferably untreated. These may be used alone or in combination of two or more.

[0066] The average particle size of component (C) is preferably 0.1 to 30 μm, more preferably 0.3 to 20 μm, particularly preferably 0.5 to 10 μm, and most preferably 1 to 8 μm. An average particle size of 0.1 μm or more will result in a cured product with excellent conductivity, while an average particle size of 30 μm or less will result in a conductive resin composition with excellent workability. Here, the average particle size of component (C) is the particle size at a cumulative volume ratio of 50% (D50) in the particle size distribution determined by laser diffraction scattering.

[0067] Component (C) preferably contains two or more types of conductive particles with different particle sizes. By including two or more types of conductive particles with different particle sizes in component (C), particles with smaller average particle sizes are closely packed into the gaps between particles with larger average particle sizes, resulting in a conductive resin composition with better conductivity. The average particle size of the particles with larger average particle sizes is preferably 3 to 30 μm, more preferably 3 to 20 μm, even more preferably 3 to 10 μm, particularly preferably 4 to 8 μm, and most preferably 5 to 8 μm. Furthermore, the average particle size of the particles with smaller average particle sizes is preferably 0.1 μm or more but less than 3 μm, more preferably 0.3 μm or more but less than 3 μm, even more preferably more than 0.3 μm but less than 3 μm, particularly preferably 0.5 to 2.5 μm, and most preferably 0.5 to 2 μm.

[0068] Thus, in one embodiment, component (C) may contain silver particles having an average particle size of 3 to 30 μm and silver particles having an average particle size of 0.1 μm or more and less than 3 μm. In another embodiment, component (C) may contain silver particles having an average particle size of 3 to 20 μm and silver particles having an average particle size of 0.3 μm or more and less than 3 μm. In another embodiment, component (C) may contain silver particles having an average particle size of 3 to 10 μm and silver particles having an average particle size of more than 0.3 μm and less than 3 μm. In another embodiment, component (C) may contain silver particles having an average particle size of 4 to 8 μm and silver particles having an average particle size of 0.5 to 2.5 μm. In another embodiment, component (C) may contain silver particles having an average particle size of 5 to 8 μm and silver particles having an average particle size of 0.5 to 2 μm.

[0069] In the above embodiment, the mass ratio (content ratio) of particles with a large average particle size to particles with a small average particle size (large particles:small particles) is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, even more preferably 25:75 to 60:40, particularly preferably 30:70 to 50:50, and most preferably 35:75 to 45:55. When the mass ratio is in the range of 10:90 to 90:10, a conductive resin composition with better conductivity can be obtained.

[0070] The tap density of the component (C) is preferably 0.1 to 100 g / cm ３ and more preferably 0.5 to 50 g / cm ２ and even more preferably 1 to 20 g / cm ３ and particularly preferably 2 to 10 g / cm ３ and most preferably 3 to 6 g / cm ３ The tap density of component (C) is 0.1 to 100 g / cm ３ Within this range, the filling rate of the conductive particles in the resin is high, and excellent conductivity can be achieved. Here, the tap density of component (C) can be measured in accordance with JIS Z 2512:2012.

[0071] The content of component (C) is preferably 100 to 1,000 parts by mass, more preferably 200 to 800 parts by mass, particularly preferably 300 to 600 parts by mass, and most preferably 400 to 500 parts by mass, per 100 parts by mass of the combined total of components (A) and (B). When the content of component (C) is 100 parts by mass or more per 100 parts by mass of the combined total of components (A) and (B), the resulting cured product will have good electrical conductivity, and when the content is 1,000 parts by mass or less, a conductive resin composition with excellent workability can be obtained.

[0072] The content of component (C) is preferably 50 to 1,000 parts by mass, more preferably 100 to 800 parts by mass, particularly preferably 200 to 600 parts by mass, and most preferably 300 to 500 parts by mass, per 100 parts by mass of the total of components (A), (B), and (E), described below. When the content of component (C) is 50 parts by mass or more, the resulting cured product has good electrical conductivity, and when the content is 1,000 parts by mass or less, a conductive resin composition with excellent workability can be obtained.

[0073] The content of component (C) is preferably 50 to 1,000 parts by mass, more preferably 100 to 800 parts by mass, particularly preferably 200 to 600 parts by mass, and most preferably 300 to 500 parts by mass, per 100 parts by mass of the total of component (A), component (B), component (E) described below, and optional monofunctional (meth)acrylate (excluding component (B)). A content of component (C) of 50 parts by mass or more results in a conductive resin composition with excellent conductivity, while a content of component (C) of 1,000 parts by mass or less results in a conductive resin composition with excellent workability. Furthermore, the content of component (C) per 100 parts by mass of component (A) is preferably 100 to 1,500 parts by mass, more preferably 300 to 1,200 parts by mass, and most preferably 500 to 1,000 parts by mass. When two or more types of component (C) are used in combination, the content of component (C) refers to the combined amount.

[0074] The content of component (C) in the entire conductive resin composition (where the total mass of the conductive resin composition is 100 mass%) is preferably 40 to 95 mass%, more preferably 50 to 90 mass%, and most preferably 60 to 85 mass%. By being in the above range, a conductive resin composition can be obtained that is easy to work with and has excellent electrical conductivity in the cured product obtained by curing at low temperatures.

[0075] <Component (D)> The component (D) used in the present invention is a thermal radical generator. The component (D) is not particularly limited as long as it is a compound that generates radicals upon application of heat, and specific examples include organic peroxides and azo compounds. In view of the fact that the component (D) can be cured at low temperatures and that the conductive resin composition has excellent conductivity after storage, the component (D) is preferably an organic peroxide, and more preferably an organic peroxide represented by the following general formula 1:

[0076]

[0077] In the above general formula 1, R １ each independently represents a linear, branched, or cyclic hydrocarbon group.

[0078] In the above general formula 1, R １ can be a linear or branched alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms. Specific examples of the linear or branched alkyl group include those described above in relation to formula (B). Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.

[0079] The above R １ is preferably a linear or branched alkyl group having 3 to 10 carbon atoms or a cycloalkyl group having 3 to 10 carbon atoms, and more preferably a linear or branched alkyl group having 3 to 8 carbon atoms.

[0080] In view of excellent low-temperature curing properties, the one-hour half-life temperature of component (D) is preferably 30 to 150°C, more preferably 35 to 100°C, particularly preferably 40 to 80°C, and most preferably 50 to 70°C. In this specification, the term "one-hour half-life temperature" refers to the temperature at which the time required for the concentration of the organic peroxide to decrease to half of the initial concentration (i.e., the half-life) is one hour. Specifically, the one-hour half-life temperature is a value measured by thermally decomposing the organic peroxide in benzene at a concentration of 0.1 mol / L.

[0081] Examples of component (D) include, but are not limited to, di-n-propyl peroxydicarbonate, di-iso-propyl peroxydicarbonate, di(4-tert-butylcyclohexyl) peroxydicarbonate (also known as bis(4-tert-butylcyclohexyl) peroxydicarbonate), di(2-ethylhexyl) peroxydicarbonate (also known as bis(2-ethylhexyl) peroxydicarbonate, bis(2-ethylhexyl) peroxydicarbonate), and di-sec-butyl peroxydicarbonate.

[0082] The content of component (D) is preferably 1 to 50 parts by mass, more preferably 1.5 to 30 parts by mass, particularly preferably 2 to 20 parts by mass, and most preferably 3 to 10 parts by mass, per 100 parts by mass of the total of components (A) and (B). When the content of component (D) is 1 part by mass or more per 100 parts by mass of the total of components (A) and (B), a conductive resin composition with excellent low-temperature curing properties can be obtained, and when the content is 50 parts by mass or less, a conductive resin composition with excellent storage stability can be obtained.

[0083] The content of component (D) is preferably 0.5 to 30 parts by mass, more preferably 1 to 20 parts by mass, particularly preferably 2 to 10 parts by mass, and most preferably 3 to 8 parts by mass, relative to 100 parts by mass of the total of components (A), (B), and (E), described below. When the content of component (D) is 0.5 parts by mass or more relative to 100 parts by mass of the total of components (A), (B), and (E), a conductive resin composition with excellent low-temperature curing properties can be obtained, and when the content is 30 parts by mass or less, a conductive resin composition with excellent storage stability can be obtained.

[0084] The content of component (D) is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 20 parts by mass, particularly preferably 1 to 10 parts by mass, and most preferably 3 to 8 parts by mass, relative to 100 parts by mass of the total amount of component (A), component (B), component (E) described below, and optional monofunctional (meth)acrylate (excluding component (B)). A content of component (D) of 0.1 parts by mass or more results in a conductive resin composition with excellent low-temperature curing properties, while a content of 50 parts by mass or less results in a conductive resin composition with excellent storage stability. Furthermore, the content of component (D) relative to 100 parts by mass of component (A) is preferably 0.1 to 50 parts by mass, more preferably 1 to 30 parts by mass, particularly preferably 3 to 20 parts by mass, and most preferably 5 to 15 parts by mass. When two or more types of component (D) are used in combination, the content of component (D) refers to the total amount.

[0085] <Component (E)> In addition to the components (A) to (D), the conductive resin composition of the present invention preferably includes, as component (E), a polyfunctional (meth)acrylate having two or more (meth)acryloyl groups in one molecule (excluding the component (A)). The polyfunctional (meth)acrylate as component (E) is a polyfunctional (meth)acrylate that does not contain a urethane bond and is other than an epoxy (meth)acrylate. In one embodiment, component (E) may be a polyfunctional (meth)acrylate monomer having two or more (meth)acryloyl groups in one molecule. The number of (meth)acryloyl groups contained in component (E) may be, for example, 2 or more and 6 or less, 3 or more and 5 or less, or 3 or more and 4 or less. By including, as component (E), a polyfunctional (meth)acrylate having two or more (meth)acryloyl groups in one molecule, a conductive resin composition with excellent adhesive strength can be obtained.

[0086] Specific examples of bifunctional (meth)acrylates (having two (meth)acryloyl groups in one molecule) as component (E) include, but are not limited to, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol (meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, neopentyl glycol-modified trimethylolpropane di(meth)acrylate, polyester (meth)acrylates having an ester bond in the molecule, polyether (meth)acrylates having an ether skeleton, polycarbonate (meth)acrylates having a carbonate skeleton, polybutadiene (meth)acrylates having a butadiene skeleton, and (meth)acrylic polymers having terminal (meth)acryloyl groups.

[0087] Specific examples of trifunctional or higher functional (meth)acrylates (having three or more (meth)acryloyl groups in one molecule) include, but are not limited to, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol poly(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, alkoxylated glycerin tri(meth)acrylate, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, and polypentaerythritol polyacrylate.

[0088] In one embodiment, the component (E) is preferably a tri- or higher functional (meth)acrylate, and more preferably dipentaerythritol penta(meth)acrylate or dipentaerythritol poly(meth)acrylate.

[0089] The content of component (E) is preferably 5 to 100 parts by mass, more preferably 10 to 60 parts by mass, and most preferably 20 to 40 parts by mass, per 100 parts by mass of component (A). When the content of component (E) is 5 parts by mass or more per 100 parts by mass of component (A), a conductive resin composition with excellent adhesive strength can be obtained, and when the content is 100 parts by mass or less, a conductive resin composition with excellent conductivity can be obtained. Note that when two or more types of component (E) are used in combination, the content of component (E) refers to the total amount.

[0090] <Optional Components> In addition to the components (A) to (D), the conductive resin composition of the present invention may or may not further contain optional components, as long as the effects of the present invention are not impaired. Furthermore, in addition to the components (A) to (E), the conductive resin composition of the present invention may or may not further contain optional components, as long as the effects of the present invention are not impaired. Examples of optional components include monofunctional (meth)acrylates (excluding the component (B)), storage stabilizers, adhesion promoters, plasticizers, fillers, tackifiers, colorants such as organic or inorganic pigments and dyes, rust inhibitors, antifoamers, dispersants, surfactants, antioxidants, light stabilizers, UV absorbers, viscoelasticity modifiers, thickeners, and organometallic complexes.

[0091] The conductive resin composition according to the present invention may or may not further contain a monofunctional (meth)acrylate (excluding the above-mentioned component (B)). The monofunctional (meth)acrylate as an optional component is distinguished from the above-mentioned component (B) in that it does not have the "ether skeleton" of the present invention. Furthermore, the monofunctional (meth)acrylate as an optional component is distinguished from the (meth)acrylate having an acidic group as an adhesion promoter described below in that it does not have an acidic group.

[0092] Specific examples of the monofunctional (meth)acrylate as an optional component include ethyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, glycidyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentenyl (meth)acrylate. Examples of the acrylate include, but are not limited to, methyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerol (meth)acrylate, and trifluoroethyl (meth)acrylate. These may be used alone or in combination.

[0093] The content of the monofunctional (meth)acrylate is preferably 0.01 to 50 parts by mass, more preferably 0.1 to 40 parts by mass, and most preferably 0.5 to 30 parts by mass, per 100 parts by mass of component (A). By ensuring that the content of the monofunctional (meth)acrylate as an optional component is in the range of 0.01 to 50 parts by mass, a conductive resin composition with excellent conductivity and adhesive strength can be obtained. When two or more types of monofunctional (meth)acrylates (optional components) are used in combination, the content of the monofunctional (meth)acrylates refers to the total amount.

[0094] The conductive resin composition of the present invention may or may not contain a storage stabilizer. Examples of storage stabilizers include a polymerization inhibitor and a chelating agent. The polymerization inhibitor can capture generated radical species, so adding this can further maintain storage stability, and the chelating agent can capture generated metal ions, so adding this can further maintain storage stability.

[0095] Specific examples of the polymerization inhibitor include quinone-based polymerization inhibitors such as hydroquinone, methoxyhydroquinone, benzoquinone, and p-tert-butylcatechol; alkylphenol-based polymerization inhibitors such as 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-methylphenol (BHT), and 2,4,6-tri-tert-butylphenol; alkylated diphenylamine, N,N'-diphenyl-p-phenylenediamine, phenothiazine, 4-hydroxy-2,2,6, Examples of polymerization inhibitors include, but are not limited to, amine-based polymerization inhibitors such as 6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 1,4-dihydroxy-2,2,6,6-tetramethylpiperidine, and 1-hydroxy-4-benzoyloxy-2,2,6,6-tetramethylpiperidine; and N-oxyl-based polymerization inhibitors such as 2,2,6,6-tetramethylpiperidine-N-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl. In one embodiment, the conductive resin composition according to the present invention preferably contains a polymerization inhibitor in addition to the above components (A) to (D) (or the above components (A) to (E)). The polymerization inhibitor is preferably an alkylphenol-based polymerization inhibitor, and particularly preferably at least one selected from the group consisting of 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-methylphenol (BHT), and 2,4,6-tri-tert-butylphenol.

[0096] Specific examples of the chelating agent include EDTA 2Na and EDTA 4Na (4NA: ethylenediamine-N,N,N',N'-tetraacetic acid tetrasodium salt tetrahydrate) manufactured by Dojin Chemical Laboratory Co., Ltd. Furthermore, examples of chelating agents that are liquid at 25°C include MZ-8 manufactured by Cherest Co., Ltd., but are not limited to these.

[0097] If the amount of storage stabilizer added is too large, the storage stability improves but the reactivity slows. Therefore, when the conductive resin composition contains a storage stabilizer, the amount of storage stabilizer added is preferably 0.001 to 1.0 mass%, more preferably 0.01 to 0.5 mass%, and most preferably 0.03 to 0.3 mass%, relative to the total mass of the conductive resin composition being 100 mass%. When two or more storage stabilizers are used in combination, the content of the storage stabilizers refers to the total amount.

[0098] The conductive resin composition of the present invention may or may not contain an adhesion promoter. Examples of adhesion promoters include (meth)acrylates having an acidic group (excluding the above-mentioned components (A), (B), and (E) and the optional monofunctional (meth)acrylates) and silane coupling agents. By including an adhesion promoter in the conductive resin composition, a conductive resin composition (cured product) with excellent adhesive strength can be obtained. Furthermore, (meth)acrylates having an acidic group are not included in the above-mentioned components (A), (B), and (E) or the optional monofunctional (meth)acrylates, and are treated as adhesion promoters. Furthermore, (meth)acryloyl group-containing silane coupling agents are not included in the above-mentioned components (A), (B), and (E) or the optional monofunctional (meth)acrylates, and are treated as adhesion promoters.

[0099] The (meth)acrylate having an acidic group refers to a carboxylic acid compound or a phosphoric acid compound having a (meth)acryloyl group in the molecule. That is, in this specification, the "(meth)acrylate having an acidic group" refers to a (meth)acrylate compound having a (meth)acryloyl group and at least one group selected from the group consisting of a carboxyl group, a phosphoric acid group, and a phosphonic acid group. Examples of carboxylic acid compounds having a (meth)acryloyl group in the molecule include (meth)acrylic acid, 3-(meth)acryloyloxypropyl succinic acid, 4-(meth)acryloyloxybutyl succinic acid, 2-(meth)acryloyloxyethyl maleic acid, 3-(meth)acryloyloxypropyl maleic acid, 4-(meth)acryloyloxybutyl maleic acid, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 3-(meth)acryloyloxypropyl hexahydrophthalic acid, 4-(meth)acryloyloxybutyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 3-(meth)acryloyloxypropyl phthalic acid, and 4-(meth)acryloyloxybutyl phthalic acid. Examples of phosphate compounds having a (meth)acryloyl group in the molecule include, but are not limited to, 2-ethylhexyl acid phosphate, 2-hydroxyethyl methacrylate acid phosphate, and dibutyl phosphate. These compounds may be used alone or in combination of two or more. By including a (meth)acrylate having an acidic group in the conductive resin composition, a conductive resin composition (cured product) with excellent adhesive strength can be obtained. In one embodiment, the conductive resin composition according to the present invention preferably further includes an adhesion promoter in addition to the above components (A) to (D) (or the above components (A) to (E)). The adhesion promoter is preferably a phosphate compound having a (meth)acryloyl group in the molecule (a (meth)acrylate compound having a (meth)acryloyl group and a phosphate group), and the phosphate compound is more preferably at least one selected from the group consisting of 2-ethylhexyl acid phosphate, 2-hydroxyethyl methacrylate acid phosphate, and dibutyl phosphate.

[0100] Specific examples of the silane coupling agent include glycidyl group-containing silane coupling agents such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 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)acryloyl group-containing silane coupling agents such as γ-(methacryloxypropyl)trimethoxysilane; amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and N-phenyl-γ-aminopropyltrimethoxysilane; and mercapto group-containing silane coupling agents such as γ-(mercaptopropyl)trimethoxysilane. These may be used alone or in combination of two or more.

[0101] The content of the adhesion promoter is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, and most preferably 0.5 to 3 parts by mass, per 100 parts by mass of component (A). By ensuring that the content of the adhesion promoter is in the range of 0.01 to 10 parts by mass, a conductive resin composition with excellent adhesive strength can be obtained. When two or more adhesion promoters are used in combination, the content of the adhesion promoters refers to the total amount.

[0102] <Method for Producing Conductive Resin> The conductive resin composition according to the present invention can be produced by a conventionally known method. That is, according to another aspect of the present invention, there is also provided a method for producing a conductive resin, comprising mixing the above-described components (A) to (D). The above-described production method may further comprise mixing component (E) and / or optional components. In this case, the order in which the components are mixed is not particularly limited. As an example, first, predetermined amounts of components (A) and (B), as well as component (E) and optional components used as needed, are weighed and mixed using a known mixing means such as a mixer. Mixing is preferably carried out at a temperature of 10 to 70°C for preferably 0.1 to 5 hours. Next, a predetermined amount of component (C) is weighed and added to the mixing means, and mixed at a temperature of 10 to 70°C for preferably 0.1 to 5 hours. Furthermore, a predetermined amount of component (D) is weighed and added to the mixing means, and mixed at a temperature of 10 to 70°C for preferably 0.1 to 5 hours, thereby producing a conductive resin composition.

[0103] The mixing order of the components is merely an example, and the mixing order of the components is not particularly limited. The components may be added to the mixing means all at once or sequentially. Furthermore, when producing the conductive resin composition, it is preferable to mix the components while vacuum degassing.

[0104] <Preferred Embodiment> Hereinafter, preferred embodiments of the conductive resin composition according to the present invention will be further described.

[0105] In one embodiment, the conductive resin composition according to the present invention is preferably substantially composed of the above-mentioned components (A) to (E), and at least one selected from the group consisting of a monofunctional (meth)acrylate (excluding the above-mentioned component (B)), a storage stabilizer, an adhesion promoter, a plasticizer, a filler, a tackifier, a colorant, a rust inhibitor, an antifoaming agent, a dispersant, a surfactant, an antioxidant, a light stabilizer, an ultraviolet absorber, a viscoelasticity modifier, a thickener, and an organometallic complex. According to another embodiment of the present invention, the conductive resin composition is preferably substantially composed of the above-mentioned components (A) to (E), and at least one selected from the group consisting of a storage stabilizer (preferably a polymerization inhibitor) and an adhesion promoter (preferably a (meth)acrylate having an acidic group). According to yet another embodiment of the present invention, the conductive resin composition is preferably substantially composed of the above-mentioned components (A) to (E), a storage stabilizer (preferably a polymerization inhibitor), and an adhesion promoter (preferably a (meth)acrylate having an acidic group). In another embodiment, the conductive resin composition preferably consists essentially of the above components (A) to (E), a polymerization inhibitor, and a (meth)acrylate having an acidic group.

[0106] In the above embodiment, "the conductive resin composition is substantially composed of X" means that the total content of X exceeds 99% by mass (upper limit: 100% by mass) (relative to the conductive resin composition), with the total mass of the conductive resin composition being 100% by mass. Preferably, the conductive resin composition is composed of X (the total content = 100% by mass). For example, the phrase "the conductive resin composition is substantially composed of at least one selected from the group consisting of the above components (A) to (E), a monofunctional (meth)acrylate (excluding the above component (B)), a storage stabilizer, an adhesion imparting agent, a plasticizer, a filler, a tackifier, a colorant, a rust inhibitor, an antifoaming agent, a dispersant, a surfactant, an antioxidant, a light stabilizer, an ultraviolet absorber, a viscoelasticity modifier, a thickener, and an organometallic complex" means that the above components (A) to (E), a monofunctional (meth)acrylate (excluding the above component (B)), a storage stabilizer, an adhesion imparting agent, a plasticizer, a filler, a tackifier, a colorant, a rust inhibitor, an antifoaming agent, a dispersant, a surfactant, an antioxidant, a light stabilizer, an ultraviolet absorber, a viscoelasticity modifier, a thickener, and an organometallic complex are substantially composed of at least one selected from the group consisting of the above components (A) to (E), a monofunctional (meth)acrylate (excluding the above component (B)), a storage stabilizer, an adhesion imparting agent, a plasticizer, a filler, a tackifier, a colorant, a rust inhibitor, an antifoaming agent, a dispersant, a surfactant, an antioxidant, a light stabilizer, an ultraviolet absorber, an The total content of the radiation absorber, viscoelasticity modifier, thickener, and organometallic complex exceeds 99% by mass (upper limit: 100% by mass) (relative to the conductive resin composition), assuming the total mass of the conductive resin composition to be 100% by mass. The conductive resin composition is preferably composed of the above components (A) to (E) and at least one selected from the group consisting of monofunctional (meth)acrylates (excluding the above component (B)), storage stabilizers, adhesion promoters, plasticizers, fillers, tackifiers, colorants, rust inhibitors, antifoaming agents, dispersants, surfactants, antioxidants, light stabilizers, UV absorbers, viscoelasticity modifiers, thickeners, and organometallic complexes (the total content = 100% by mass). In another embodiment, the conductive resin composition is preferably composed of the above components (A) to (E) and at least one selected from the group consisting of storage stabilizers (preferably polymerization inhibitors) and adhesion promoters (preferably (meth)acrylates having an acidic group) (the total content = 100% by mass). Furthermore, in another embodiment, it is preferable that the conductive resin composition is composed of the above components (A) to (E), a storage stabilizer (preferably a polymerization inhibitor), and an adhesion promoter (preferably a (meth)acrylate having an acidic group) (the above total content=100% by mass).Furthermore, in another embodiment, it is preferable that the conductive resin composition is composed of the above components (A) to (E), a polymerization inhibitor, and a (meth)acrylate having an acidic group (the above total content=100% by mass).

[0107] In each of the above embodiments, the preferred contents of the components (A) to (E), the storage stabilizer (polymerization inhibitor), and the adhesion promoter (a (meth)acrylate having an acidic group) can be selected and combined by referring to the content ranges described in the sections describing each of the above components.

[0108] [Cured Product] A cured product can be obtained by applying heat (heating) to the conductive resin composition according to the present invention. That is, according to another aspect of the present invention, a cured product obtained by curing the conductive resin composition is also provided. In one embodiment, the conductive resin composition according to the present invention can be applied to an adherend, and then heat (heating) the conductive resin composition to obtain a cured product.

[0109] [Coating Method] The method for applying the conductive resin composition according to the present invention to an adherend is not particularly limited, and may be, for example, dispensing using an automatic coater, spraying, inkjet printing, screen printing, gravure printing, dipping, spin coating, or the like.

[0110] [Curing Method] The conductive resin composition according to the present invention can be cured by applying heat (heating). The heat source used in this case is not particularly limited, and any known heat source, such as a hot air drying oven, can be used.

[0111] The curing temperature of the conductive resin composition according to the present invention is preferably 25 to 120°C, more preferably 50 to 100°C, and most preferably 70 to 90°C. Thus, the conductive resin composition according to the present invention can be cured even at low temperatures. Furthermore, the curing time is not particularly limited, but is preferably 5 to 120 minutes, more preferably 10 to 120 minutes, particularly preferably 30 to 90 minutes, and most preferably 45 to 75 minutes. If the curing time is 5 minutes or longer, a cured product with excellent adhesive strength can be obtained, and if the curing time is 120 minutes or less, a cured product with excellent conductivity can be obtained.

[0112] [Uses] The conductive resin composition according to the present invention and the cured product obtained using the same can be suitably used in electronic components and the like that require electrical conductivity. In particular, since the conductive resin composition according to the present invention can be cured even at low temperatures, it can be suitably used in components that use heat-sensitive plastics and the like. Specific examples include liquid crystal image display elements, organic EL elements, solar cell elements, camera modules, flexible printed circuit boards, wearable devices, and battery packs. Examples of plastics that can be adhered include polypropylene, polyethylene, polyurethane, ABS resin (acrylonitrile-butadiene-styrene copolymer), phenolic resin, CFRP (carbon fiber reinforced plastic), GFRP (glass fiber reinforced plastic), 6,6-nylon, PPS resin (polyphenylene sulfide), and PBT resin (polybutylene terephthalate).

[0113] In one embodiment, the conductive resin composition and cured product according to the present invention are preferably used on an adherend whose outermost surface is nickel. In an adherend whose outermost surface is nickel, a nickel oxide film may be formed on the outermost surface. Although the exact reason is not clear, the conductive resin composition and cured product according to the present invention can improve the adhesive strength and conductivity of such adherends. The adherend whose outermost surface is nickel is not particularly limited, and is mainly nickel-plated, for example, electroplated or electroless plated SPCC (Steel Plate Cold Commercial), stainless steel, or copper (electric wire, printed circuit board, etc.).

[0114] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. Hereinafter, the conductive resin composition may also be simply referred to as the "composition." Unless otherwise specified, operations and tests were performed in an environment of 23°C and 50% relative humidity. Unless otherwise specified, concentrations and percentages represent mass concentrations and mass percentages, respectively, and ratios represent mass ratios, unless otherwise specified.

[0115] [Preparation of Compositions] <Examples 1 and 2, Comparative Examples 1 to 5> The following components were prepared to prepare the compositions.

[0116] Component (A): Component (A1) and / or Component (A2) Below Component (A1): Urethane (meth)acrylate having two or more (meth)acryloyl groups in one molecule Urethane acrylate having a polyether skeleton (NK Oligo UA-160™ bifunctional (number of acryloyl groups: 2) weight average molecular weight (Mw): 1,600, manufactured by Shin-Nakamura Chemical Co., Ltd.) Component (A2): Epoxy (meth)acrylate having two or more (meth)acryloyl groups in one molecule Bisphenol A type epoxy acrylate (EBECRYL (registered trademark) 3708 bifunctional (number of acryloyl groups: 2) weight average molecular weight (Mw): 1,500, manufactured by Daicel Allnex Corporation) Component (B): Monofunctional (meth)acrylate having an ether skeleton Monofunctional (meth)acrylate having a skeleton derived from polypropylene glycol (NK Ester AM-30PG Methoxytripropyleneglycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) Monofunctional (meth)acrylate having a phenoxy group and a polyether skeleton (NK Ester AMP-20GY, phenoxydiethyleneglycol acrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.) {Component (B'): (meth)acrylate other than component (B)} Monofunctional (meth)acrylate 1 (2-hydroxyethyl methacrylate) Monofunctional (meth)acrylate 2 (4-hydroxybutyl acrylate) Monofunctional (meth)acrylate 3 (isobornyl acrylate) Monofunctional (meth)acrylate 4 (n-octyl acrylate) {Component (C): Conductive particles} Silver particles 1 (Silbestos TC-508, flake-like, average particle size: 5.5 μm, tap density: 5.5 g / cm ３ Tokuriki Honten Co., Ltd.) Silver particles 2 (AC-6652 flakes, average particle size: 1.1 μm, tap density: 3.4 g / cm ３(Product of NYLON METALOR CO., LTD.) {Component (D): Thermal radical generator} Organic peroxide (di(2-ethylhexyl) peroxydicarbonate, one-hour half-life temperature: 59°C) {Component (E): Polyfunctional (meth)acrylate having two or more (meth)acryloyl groups in one molecule} Tri- or higher functional (meth)acrylate (NK Ester A-9570W, dipentaerythritol polyacrylate, product of Shin-Nakamura Chemical Co., Ltd.) Bifunctional (meth)acrylate having an ether skeleton (Light Acrylate 9EG-A, polyethylene glycol diacrylate, product of Kyoeisha Chemical Co., Ltd.) {Optional components} (meth)acrylate having an acidic group (JPA-514, 2-hydroxyethyl methacrylate acid phosphate, product of Johoku Chemical Co., Ltd.) Storage stabilizer (2,6-di-tert-butyl-4-methylphenol (BHT)).

[0117] The conductive resin compositions of Examples 1 and 2 and Comparative Examples 1 to 5 were each prepared according to the following procedure. Component (A), component (B) (or component (B')), component (E), and optional components were weighed and placed in a stirring vessel, followed by stirring for 60 minutes. Then, component (C) was weighed and placed in the stirring vessel, followed by stirring for 60 minutes while vacuum degassing. Finally, component (D) was weighed and placed in the stirring vessel, followed by stirring for 60 minutes while vacuum degassing. The blending amounts (contents) of each component are shown in Table 1, and all numerical values ​​are in parts by mass. A blank cell for each component indicates that the component was not added (amount added: 0 parts by mass).

[0118] [Evaluation] <Conductivity Test> Masking tape (50 μm thick) was attached to a glass plate measuring 2.0 mm thick, 50 mm wide, and 100 mm long, so that the exposed surface of the glass plate was 100 mm long and 10 mm wide. Each of the compositions was applied to the glass plate using a squeegee to form a uniform coating, and then the masking tape was removed to prepare test pieces (n=2). The test pieces were each placed in a hot air drying oven in an 80°C atmosphere, left for 60 minutes, and then removed from the oven. This procedure formed a cured product of the composition (100 mm long and 10 mm wide) on the glass plate. After the temperature of the test pieces had cooled to 25°C, a dual display multimeter equipped with plate-shaped electrodes was used to measure the "resistance (Ω)" by touching each electrode to the cured product with a distance of 50 mm between the electrodes. The "volume resistivity (×10 －５ The conductivity of the cured product was calculated to be 2.5×10 Ω·m, and this was used as the "electrical conductivity" value in Table 1 below. －５ It is preferable that the resistance is Ω·m or less, and 2.0×10 －５ It is more preferable that the resistance is Ω·m or less, and 1.8×10 －５ The lower limit of the electrical conductivity is particularly preferably less than Ω·m. －５ It is preferably Ω·m or more.

[0119] <Conductivity Test After Storage at 25°C (Normal Temperature)> Each composition was weighed into a non-breathable ointment container and stored in a sealed condition at 25°C for 48 hours. Thereafter, a cured product was prepared using the composition in the same manner as in the above-mentioned conductivity test, and the volume resistivity (×10 －５ The conductivity after storage at 25°C was measured, and the obtained value was taken as "electrical conductivity after storage at 25°C." From the viewpoint of ensuring good electrical conductivity, the electrical conductivity after storage at 25°C was set to 2.5 × 10 －５ It is preferable that the resistance is Ω·m or less, and 2.0×10 －５ It is more preferable that the resistance is Ω·m or less, and 1.8×10 －５The lower limit of the conductivity after storage at 25°C is particularly limited, but is preferably 0.01 × 10 －５ Preferably, it is Ω·m or more. Furthermore, in order to ensure stable conductivity regardless of the timing of use, the rate of change (rate of change in conductivity) relative to the initial value of "conductivity" is preferably -30 to 30%, more preferably -20 to 20%, and particularly preferably -15 to 15%. The rate of change is a value calculated using the following formula. In the formula below, "conductivity after storage at 25°C" is the volume resistivity value obtained by the above-mentioned <Conductivity test after storage (keeping) at 25°C (room temperature)>, and "conductivity" is the volume resistivity value obtained by the above-mentioned <Conductivity test>.

[0120]

[0121] <Adhesion Strength Test> Masking tape (50 μm thick) was applied to an electroless nickel-plated plate measuring 1.6 mm thick, 25 mm wide, and 100 mm long, so that the exposed surface of the nickel-plated plate was 100 mm long and 5 mm wide. Each of the compositions was applied to the nickel-plated plate using a squeegee to form a uniform coating, and then the masking tape was removed. A 2φ x 1 mm ceramic tip was then dropped vertically onto the coating from 1 cm above the coating to prepare test pieces (n = 5). The test pieces were heated in a hot air oven at 80°C for 60 minutes to cure the composition, and the test pieces were used. After the test pieces cooled to room temperature, a digital force gauge with contacts was moved at 50 mm / min with the nickel-plated plate fixed in place. The contacts pressed the tip perpendicular to the long edge of the test piece to measure the "maximum strength (N)." The "tip adhesive strength (MPa)" was calculated from the adhesive area, and the resulting value was used as the "adhesion strength." The adhesive strength is preferably 4.5 MPa or more, more preferably 5.0 MPa or more, and particularly preferably 6.0 MPa or more. There is no particular upper limit to the adhesive strength, but it is preferably 30 MPa or less.

[0122]

[0123] The compositions of Examples 1 and 2 containing components (A) to (D) of the present invention were curable at temperatures as low as 80°C, and the cured products obtained from these compositions exhibited excellent conductivity after storage at 25°C for 48 hours. Furthermore, the cured products of Examples 1 and 2 exhibited a small, favorable rate of change in conductivity after storage relative to the initial conductivity. Furthermore, the cured products of Examples 1 and 2 also exhibited excellent adhesive strength. On the other hand, the compositions of Comparative Examples 1 to 4 contained a monofunctional (meth)acrylate without an ether skeleton (component (B')) instead of component (B) of the present invention. However, the cured products obtained from all of these compositions exhibited low conductivity (high volume resistivity) after storage at 25°C for 48 hours, resulting in a large (poor) rate of change in conductivity before and after storage. Furthermore, the composition of Comparative Example 5 contained a bifunctional (meth)acrylate with a polyether skeleton (component (E)) instead of component (B), resulting in low conductivity both initially and after storage (high volume resistivity).

[0124] The conductive resin composition and cured product according to the present invention have excellent conductivity and adhesive strength, making them useful for conductive and adhesive applications in the miniaturized electrical and electronic components of recent years. They can particularly reduce resistance to metals such as nickel, which tend to have low conductivity. Furthermore, the resulting cured product exhibits a small rate of change in conductivity after long-term storage compared to before storage. Therefore, even when the conductive resin composition according to the present invention is used in small amounts multiple times using a dispenser or the like, the physical properties of the resulting cured product are less likely to change depending on the timing of preparation, resulting in a stable cured product. These properties allow the present invention to be used in the assembly of various electrical and electronic components, and it has the potential to be deployed in a wide range of applications.

[0125] This application is based on Japanese Patent Application No. 2024-112126, filed on July 12, 2024, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A conductive resin composition comprising the following components (A) to (D): Component (A): at least one of the following components (A1) and (A2): Component (A1): a urethane (meth)acrylate having two or more (meth)acryloyl groups in one molecule; Component (A2): an epoxy (meth)acrylate having two or more (meth)acryloyl groups in one molecule (excluding the aforementioned component (A1)); Component (B): a monofunctional (meth)acrylate having an ether skeleton; Component (C): conductive particles; and Component (D): a thermal radical generator.

2. The conductive resin composition according to claim 1, wherein the component (A1) is a urethane (meth)acrylate having two or more (meth)acryloyl groups and a polyether skeleton in one molecule.

3. The conductive resin composition according to claim 1, wherein the component (A) comprises the component (A1) and the component (A2), the component (A1) is a urethane (meth)acrylate having two or more (meth)acryloyl groups and a polyether skeleton in one molecule, and the component (A2) is a bisphenol-type epoxy (meth)acrylate having two or more (meth)acryloyl groups in one molecule.

4. The conductive resin composition according to claim 1, wherein the component (B) is at least one of a monofunctional (meth)acrylate having a skeleton derived from polypropylene glycol and a monofunctional (meth)acrylate having a phenoxy group and a polyether skeleton.

5. The conductive resin composition according to claim 1, wherein the component (B) is contained in an amount of 20 to 150 parts by mass per 100 parts by mass of the component (A).

6. The conductive resin composition according to claim 1, wherein component (C) contains silver particles having an average particle size of 3 to 30 μm and silver particles having an average particle size of 0.1 μm or more but less than 3 μm.

7. The conductive resin composition according to claim 1, further comprising, as component (E), a polyfunctional (meth)acrylate having two or more (meth)acryloyl groups in one molecule (excluding component (A)).

8. A cured product obtained by curing the conductive resin composition according to any one of claims 1 to 7.

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