Electroconductive resin composition and cured object therefrom

Abstract

Provided is an electroconductive resin composition which can be cured at low temperatures (e.g., 50-100°C) and gives a cured object having excellent electrical conductivity and excellent flexibility. The electroconductive resin composition comprises the following (A) to (D) components. (A) component, a urethane (meth)acrylate having two or more (meth)acryloyl groups in the molecule; (B) component, a polyfunctional (meth)acrylate (which is not a urethane (meth)acrylate) having a skeleton derived from a polyalkylene glycol; (C) component, electroconductive particles; (D) component, 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 50 to 100°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, conductive resin compositions that cure at low temperatures, such as 50 to 100°C, need to contain a highly reactive resin in order to undergo sufficient reaction at low temperatures. If a highly reactive resin is used, the conductivity of the cured product may deteriorate, or the cured product may become too hard, causing it to peel off when stress is generated and unable to follow the deformation of the adherend.

[0004] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a conductive resin composition that can be cured at low temperatures (for example, 50 to 100°C) and that produces a cured product having excellent conductivity and flexibility.

[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, such as 50 to 100°C, and that can give a cured product having excellent conductivity and flexibility, and thus 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): a urethane (meth)acrylate having two or more (meth)acryloyl groups in one molecule; component (B): a polyfunctional (meth)acrylate (excluding urethane (meth)acrylate) having a skeleton derived from polyalkylene glycol; component (C): conductive particles; and component (D): a thermal radical generator. [2] The conductive resin composition according to [1], wherein the component (A) is a urethane (meth)acrylate having a polyether skeleton and two or more (meth)acryloyl groups in one molecule. [3] The conductive resin composition according to [1] or [2], further comprising an epoxy (meth)acrylate as component (E). [4] The conductive resin composition according to [3], wherein the content of the component (E) is 50 to 250 parts by mass per 100 parts by mass of the component (A). [5] The conductive resin composition according to any one of [1] to [4], wherein the component (B) is a polyfunctional (meth)acrylate having a skeleton derived from polypropylene glycol. [6] The conductive resin composition according to any one of [1] to [4], wherein the component (B) is a bifunctional (meth)acrylate having a skeleton derived from polyalkylene glycol. [7] The conductive resin composition according to any one of [1] to [6], wherein the content of the component (B) is 50 to 500 parts by mass per 100 parts by mass of the component (A). [8] The conductive resin composition according to any one of [1] to [7], 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. [9] The conductive resin composition according to [3], wherein the conductive resin composition is substantially free of (meth)acrylates other than the component (A), the component (B), and the component (E).

[10] A cured product obtained by curing the conductive resin composition according to any one of [1] to [9].

[11] A method for producing a conductive resin composition, comprising mixing the following components (A) to (D): component (A): a urethane (meth)acrylate having two or more (meth)acryloyl groups in one molecule; component (B): a polyfunctional (meth)acrylate (excluding urethane (meth)acrylate) having a skeleton derived from polyalkylene glycol; component (C): conductive particles; and component (D): a thermal radical generator.

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

[11] , wherein the component (A) is a urethane (meth)acrylate having a polyether skeleton and two or more (meth)acryloyl groups in one molecule.

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

[11] or

[12] , further comprising mixing an epoxy (meth)acrylate as the component (E).

[14] The method for producing a conductive resin composition according to

[13] , wherein the content of the component (E) is 50 to 250 parts by mass per 100 parts by mass of the component (A).

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

[11] to

[14] , wherein the component (B) is a polyfunctional (meth)acrylate having a skeleton derived from polypropylene glycol.

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

[11] to

[14] , wherein the component (B) is a bifunctional (meth)acrylate having a skeleton derived from polyalkylene glycol.

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

[11] to

[16] , wherein the content of the component (B) is 50 to 500 parts by mass per 100 parts by mass of the component (A).

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

[11] to

[17] , 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.

[19] The method for producing a conductive resin composition according to

[13] , wherein the conductive resin composition is substantially free of (meth)acrylates other than the components (A), (B), and (E).

[0007] The present invention will be described in detail below. 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 combined in any manner 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 "at least X and at most Y", 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, the term "(meth)acryloyl" means both acryloyl and methacryloyl, and the term "(meth)acrylate" means both acrylate and methacrylate. For example, the term "(meth)acryloyl group" means an acryloyl group (H ２ C=CH-C(=O)-) and methacryloyl groups (H ２ C=C(CH ３ )-C(=O)-). "A and / or B" means that A, B, and combinations thereof are included.

[0010] 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] In this specification, unless otherwise specified, concentrations and % represent mass concentrations and mass %, respectively, and ratios represent mass ratios unless otherwise specified. Unless otherwise specified, operations and measurements of physical properties, etc. are performed under conditions of room temperature (23°C) and a relative humidity of 40 to 55% RH.

[0012] One aspect of the present invention is a conductive resin composition comprising the following components (A) to (D): component (A): a urethane (meth)acrylate having two or more (meth)acryloyl groups in one molecule; component (B): a polyfunctional (meth)acrylate (excluding urethane (meth)acrylate) having a skeleton derived from polyalkylene glycol; component (C): conductive particles; and component (D): a thermal radical generator.

[0013] The conductive resin composition of the present invention can be cured at low temperatures such as 50 to 100° C., and can give a cured product with excellent conductivity and flexibility.

[0014] The component (A) used in the present invention is not particularly limited as long as it is a urethane (meth)acrylate having two or more (meth)acryloyl groups in one molecule. The (meth)acryloyl group can be contained in the component (A) in the form of a (meth)acryloyloxy group. A "urethane (meth)acrylate" is an ester compound having a urethane bond and a (meth)acryloyl group. In other words, 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. The number of urethane bonds in the component (A) needs to be one or more per molecule.

[0015] Component (A) may further contain a structure other than a urethane bond and a (meth)acryloyl group, such as 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.

[0016] The component (A) may be either a synthetic product or a commercially available product. Methods for synthesizing a urethane (meth)acrylate include, but are not limited to, 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.

[0017] In view of excellent electrical conductivity, component (A) is preferably a urethane (meth)acrylate having a polyether skeleton and two or more (meth)acryloyl groups in one molecule. 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 alkylene oxides such as polyethylene oxide, polypropylene oxide, and polybutylene glycol.

[0018] In the component (A), the number of (meth)acryloyl groups contained in one molecule is, for example, 2 to 6, preferably 2 to 4, more preferably 2 or 3, and particularly preferably 2.

[0019] 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, polycarbonate diol, etc. Among these, it is preferable that the polyol compound has a polyether skeleton because it has excellent conductivity.

[0020] Examples of the polyisocyanate compound include aliphatic polyisocyanate compounds such as tetramethylene diisocyanate, hexamethylene diisocyanate, and 2-methyl-1,5-pentane diisocyanate; alicyclic polyisocyanate compounds such as 1-methylcyclohexane-2,4-diisocyanate, isophorone diisocyanate, and dicyclohexylmethane-4,4'-diisocyanate; and aromatic polyisocyanate compounds such as 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, m-xylylene diisocyanate, and the like, but are not limited to these.

[0021] 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.

[0022] The weight-average molecular weight (Mw) of component (A) is preferably 500 to 50,000, more preferably 500 to 10,000, and most preferably 1,000 to 5,000. The weight-average molecular weight (Mw) of component (A) may be 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 conductivity. Here, the weight-average molecular weight is a value measured by gel permeation chromatography (GPC) using polystyrene as a standard substance.

[0023] In order to improve the desired effect, component (A) is preferably a urethane (meth)acrylate oligomer. 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.

[0024] Commercially available products of the component (A) are not particularly limited, but include 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.

[0025] The content of the above-mentioned component (A) is preferably 5 to 80% by mass, more preferably 10 to 70% by mass, and most preferably 15 to 60% by mass, relative to the total amount (100% by mass) of the resin components in the conductive resin composition. In this specification, component (A) and component (B), which will be described later, are collectively referred to as the "resin component." When the conductive resin composition further contains component (E), which will be described later, and / or an optional (meth)acrylate other than components (A), (B), and (E), components (A) and (B) and component (E) and / or an optional (meth)acrylate other than components (A), (B), and (E) are collectively referred to as the "resin component." When the conductive resin composition contains an adhesion promoter (a (meth)acrylate having an acidic group and a (meth)acrylic group-containing silane coupling agent), which will be described later, the (meth)acrylate having an acidic group and the (meth)acrylic group-containing silane coupling agent are not included in the resin component. When the content of the (A) component is 5% by mass or more, a conductive resin composition having excellent conductivity and flexibility of the cured product can be obtained, and when the content of the (A) component is 80% by mass or less, a conductive resin composition having excellent adhesive strength can be obtained.

[0026] The component (B) used in the present invention is a polyfunctional (meth)acrylate having a skeleton derived from polyalkylene glycol. This component is not particularly limited as long as it is a polyfunctional (meth)acrylate having a skeleton derived from polyalkylene glycol. However, this excludes the urethane (meth)acrylate having two or more (meth)acryloyl groups per molecule, which is the component (A). Since polyfunctional (meth)acrylates having a urethane bond and a skeleton derived from polyalkylene glycol are treated as component (A), component (B) is a compound without a urethane bond. Furthermore, epoxy (meth)acrylates, which are component (E) described below, are not included in component (B). Component (B) does not include urethane (meth)acrylates or epoxy (meth)acrylates. The number of functional groups (the number of (meth)acryloyl groups) of component (B) is not particularly limited as long as it is two or more, but from the viewpoints of adhesive strength and flexibility, it is preferably 2 to 6, more preferably 2 to 3, and most preferably 2.

[0027] In the polyalkylene glycol-derived skeleton, the number of repeating units derived from alkylene glycol is preferably 2 to 20, more preferably 2 to 15, and most preferably 2 to 10. When the number of repeating units derived from alkylene glycol is 2 to 20, a conductive resin composition can be obtained that exhibits excellent electrical conductivity and reduced outgassing in the cured product. Examples of polyalkylene glycol-derived skeletons include skeletons derived from polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc. The polyalkylene glycol-derived skeleton is preferably a skeleton derived from polyethylene glycol and / or a skeleton derived from polypropylene glycol in terms of excellent electrical conductivity, and more preferably a skeleton derived from polypropylene glycol in terms of excellent outgassing reduction, but is not limited to these. Component (B) may contain one or more of these in a single molecule.

[0028] Furthermore, the component (B) may contain, in addition to the polyalkylene glycol-derived skeleton, a skeleton other than that derived from polyalkylene glycol. Specific examples include skeletons derived from aliphatic hydrocarbons, aromatic hydrocarbons, esters, carbonates, etc. From the viewpoint of achieving excellent electrical conductivity of the cured product after storage at room temperature, it is preferable that the component (B) contain a skeleton derived from an aliphatic hydrocarbon and / or an aromatic hydrocarbon.

[0029] Specific examples of bifunctional (meth)acrylates having a skeleton derived from polyalkylene glycol include, but are not limited to, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol (meth)acrylate, PO-modified neopentyl glycol di(meth)acrylate, etc. These may be used alone or in combination of two or more.

[0030] Specific examples of trifunctional or higher functional (meth)acrylates having a skeleton derived from polyalkylene glycol include, but are not limited to, dipentaerythritol penta(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, alkoxylated glycerin tri(meth)acrylate, ditrimethylolpropane tetraacrylate, alkoxylated pentaerythritol poly(meth)acrylate, etc. These may be used alone or in combination of two or more.

[0031] The content of the (B) component is preferably 5 to 80% by mass, more preferably 10 to 70% by mass, and most preferably 20 to 60% by mass, relative to 100% by mass of the total resin components. The content of the (B) component may be 30 to 50% by mass, relative to 100% by mass of the total resin components. A content of the (B) component of 5% by mass or more can provide a conductive resin composition with excellent workability and reduced outgassing. A content of the (B) component of 80% by mass or less can provide a conductive resin composition with excellent conductivity of the cured product. Furthermore, the content of the (B) component is preferably 50 to 500 parts by mass, more preferably 75 to 400 parts by mass, even more preferably 100 to 300 parts by mass, and most preferably 200 to 300 parts by mass, relative to 100 parts by mass of the (A) component. The content of the (B) component may be 100 to 250 parts by mass, relative to 100 parts by mass of the (A) component. When two or more types of component (B) are used in combination, the content of component (B) refers to the total amount.

[0032] In a preferred embodiment, the component (B) contains a bifunctional (meth)acrylate having a backbone derived from two different types of polyalkylene glycol (a bifunctional (meth)acrylate having a backbone derived from a first polyalkylene glycol and a bifunctional (meth)acrylate having a backbone derived from a second polyalkylene glycol).

[0033] In the bifunctional (meth)acrylate having a skeleton derived from the first polyalkylene glycol, the number of repeating units derived from the alkylene glycol is 2 to 5, and preferably 3.

[0034] In the bifunctional (meth)acrylate having a skeleton derived from the second polyalkylene glycol, the number of repeating units derived from the alkylene glycol is 6 to 10, and preferably 9.

[0035] The bifunctional (meth)acrylate having a skeleton derived from the first polyalkylene glycol and the bifunctional (meth)acrylate having a skeleton derived from the second polyalkylene glycol preferably have skeletons derived from the same polyalkylene glycol. In the bifunctional (meth)acrylate having a skeleton derived from the first polyalkylene glycol and the bifunctional (meth)acrylate having a skeleton derived from the second polyalkylene glycol, the skeleton derived from the polyalkylene glycol is preferably a skeleton derived from polyethylene glycol or polypropylene glycol.

[0036] The mass ratio of the bifunctional (meth)acrylate having a skeleton derived from the first polyalkylene glycol to the bifunctional (meth)acrylate having a skeleton derived from the second polyalkylene glycol is not particularly limited and is, for example, 3:7 to 7:3, preferably 4:6 to 6:4, and more preferably 5:5.

[0037] 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. The component (C) can be appropriately selected from, for example, metal particles composed of one or more metals selected from the group consisting of gold, silver, copper, nickel, palladium, platinum, tin, bismuth, etc., alloy particles composed of a combination of multiple (two or more) of these metal particles, or 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 metals). These (conductive particles) may be used alone, or two or more types may be used in combination. From the standpoints of conductivity, cost, etc., the component (C) is preferably silver particles or particles coated on the surface with a coating layer of silver, and more preferably silver particles.

[0038] The shape of component (C) may be spherical, amorphous, flake-like, filament-like (needle-like), or dendritic, with flake-like being preferred due to its excellent conductivity. In this specification, "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. These (conductive particles) may be used alone or in combination of two or more types.

[0039] Component (C) may be surface-treated with a lubricant. Saturated and / or unsaturated fatty acids can be used as the lubricant. Examples of the solvent 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. From the viewpoint of achieving excellent adhesive strength during low-temperature curing and excellent electrical conductivity of the cured product, component (C) is preferably selected from the group consisting of untreated conductive particles and conductive particles treated with stearic acid and oleic acid, and more preferably untreated conductive particles. These conductive particles may be used alone or in combination of two or more types.

[0040] The average particle size of the component (C) is preferably 0.1 to 30 μm, more preferably 0.3 to 20 μm, and most preferably 0.5 to 10 μm. The average particle size of the component (C) may be 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 the component (C) is the particle size (D50) at a cumulative volume ratio of 50% in the particle size distribution determined by laser diffraction scattering.

[0041] The 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 the 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 particles with larger average particle sizes preferably have an average particle size of 3 to 30 μm, more preferably 3 to 20 μm, and most preferably 3 to 10 μm. The particles with larger average particle sizes may also have an average particle size of 4 to 8 μm or 5 to 8 μm. The particles with smaller average particle sizes preferably have an average particle size of 0.1 μm or more but less than 3 μm, more preferably 0.3 μm or more but less than 3 μm, and most preferably more than 0.3 μm but less than 3 μm. The particles with smaller average particle sizes may also have an average particle size of 0.5 to 2.5 μm or 0.5 to 2 μm.

[0042] In one embodiment, component (C) may include 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 include 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 include 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 include 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 include 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.

[0043] When component (C) contains two or more types of conductive particles with different particle sizes, the mass ratio (content ratio) of the particles with the larger average particle size to the particles with the smaller average particle size is preferably 10:90 to 90:10, more preferably 20:80 to 20:80, and most preferably 25:75 to 60:40. The mass ratio may be 30:70 to 50:50 or 35:75 to 45:55. A mass ratio in the range of 10:90 to 90:10 can provide a conductive resin composition with better conductivity.

[0044] 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 most preferably 1 to 20 g / cm ３ The tap density of component (C) is 2 to 10 g / cm ３ or 3 to 6 g / cm ３ The tap density of component (C) may be 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.

[0045] The content of the (C) component is preferably 50 to 1,000 parts by mass, more preferably 100 to 800 parts by mass, and most preferably 200 to 600 parts by mass, per 100 parts by mass of the total resin components. The content of the (C) component may be 300 to 500 parts by mass, per 100 parts by mass of the total resin components. A content of the (C) component of 50 parts by mass or more results in a conductive resin composition with excellent conductivity, and a content of the (C) component of 1,000 parts by mass or less results in a conductive resin composition with excellent workability. The content of the (C) component is preferably 500 to 3,500 parts by mass, more preferably 1,000 to 3,000 parts by mass, and most preferably 1,500 to 2,500 parts by mass, per 100 parts by mass of the (A) component. When two or more (C) components are used in combination, the content of the (C) component refers to the combined amount.

[0046] The content of component (C) is preferably 40 to 95 mass% relative to the entire conductive resin composition (100 mass% of the conductive resin composition), more preferably 50 to 90 mass%, and most preferably 60 to 85 mass%. The content of component (C) may be 75 to 85 mass% relative to the entire conductive resin composition (100 mass% of the conductive resin composition). By having the content in the above range, a conductive resin composition with excellent workability and conductivity can be obtained.

[0047] 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 when heated, and specific examples include organic peroxides and azo compounds. The component (D) is preferably an organic peroxide, more preferably an organic peroxide represented by the following general formula 1, because it can be cured at low temperatures and the conductive resin composition has excellent conductivity after storage. R in the following general formula 1 １ each independently refers to a hydrocarbon group, which can be linear, branched, cyclic, and combinations thereof, meaning that a linear, branched, or cyclic hydrocarbon group is substituted with a linear, branched, and / or cyclic hydrocarbon group.

[0048]

[0049] In the above general formula 1, R １may 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 a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a tert-pentyl group, a neopentyl group, a 1,2-dimethylpropyl group, an n-hexyl group, an isohexyl group, a 1,3-dimethylbutyl group, a 1-isopropylpropyl group, a 1,2-dimethylbutyl group, an n-heptyl group, a 1,4-dimethylpentyl group, a 3-ethylpentyl group, a 2-methyl-1-isopropylpropyl group, a 1-ethyl-3-methylbutyl group, an n-octyl group, and a 2-ethylhexyl group. Specific examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group.

[0050] The above R １ is preferably a linear or branched alkyl group having 3 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, or a combination thereof, and more preferably a linear or branched alkyl group having 3 to 8 carbon atoms, or a combination thereof.

[0051] In view of its excellent low-temperature curing properties, the one-hour half-life temperature of the above-mentioned component (D) is preferably 30 to 150°C, more preferably 35 to 100°C, and most preferably 40 to 80°C. The one-hour half-life temperature may be 50 to 70°C. The "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 thermal decomposition in benzene at a peroxide concentration of 0.1 mol / L.

[0052] Examples of the 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, and di-sec-butyl peroxydicarbonate.

[0053] The content of the (D) component is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 20 parts by mass, and most preferably 1 to 10 parts by mass, per 100 parts by mass of the total amount of the resin components. The content of the (D) component may be 3 to 8 parts by mass. A content of the (D) component of 0.1 parts by mass or more results in a conductive resin composition with excellent low-temperature curing properties, and a content of the (D) component of 50 parts by mass or less results in a conductive resin composition with excellent storage stability. The content of the (D) component is preferably 0.1 to 50 parts by mass, more preferably 1 to 40 parts by mass, and most preferably 5 to 30 parts by mass, per 100 parts by mass of the (A) component.

[0054] The conductive resin composition according to the present invention may further contain an epoxy (meth)acrylate as component (E), excluding component (A). Since an epoxy (meth)acrylate having a urethane bond is treated as component (A), component (E) is an epoxy (meth)acrylate without a urethane bond. Component (E) can be synthesized by ring-opening polymerization of acrylic acid or the like with the glycidyl group of a glycidyl ether compound, but is not limited to this method. The main chain of the glycidyl ether compound can have various skeletons, such as bisphenol A, bisphenol F, phenol novolac, hydrogenated bisphenol A, and hydrogenated bisphenol F. From the viewpoint of excellent adhesive strength, the main chain of the glycidyl ether compound preferably has a structure derived from a bisphenol type, and more preferably a structure derived from a bisphenol A type. In this specification, ethylene oxide-modified and propylene oxide-modified glycidyl ethers are also treated as component (E). Component (E) may be used alone, or two or more types may be used in combination.

[0055] The number of functional groups in component (E) is not particularly limited, but from the viewpoint of adhesive strength and flexibility, it is preferably 1 to 6, more preferably 1 to 4, and most preferably 2. In component (E), unreacted glycidyl groups may remain in the molecule.

[0056] The weight-average molecular weight (Mw) of component (E) is preferably 200 to 5,000, more preferably 250 to 3,000, and most preferably 300 to 2,000. A weight-average molecular weight of 200 or more results in a cured product with excellent adhesive strength and reduced outgassing, while a weight-average molecular weight of 5,000 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.

[0057] Commercially available products of the component (E) include, but are not limited to, EBECRYL (registered trademark) 3700, 3708 (manufactured by Daicel Allnex Corporation), Epoxy Ester 3000A, 3002A, M-600A, 40EM (manufactured by Kyoeisha Chemical Co., Ltd.), BAEA-100, BAEM-100, BEEA-50, PNEM-50 (manufactured by KSM Corporation), NK Oligo (registered trademark) EA-1010N, EA-1010LC, EA-1020LC3, etc. These may be used alone, or two or more types may be used in combination.

[0058] The content of component (E) is preferably 20 to 300 parts by mass, more preferably 50 to 250 parts by mass, and most preferably 100 to 200 parts by mass, per 100 parts by mass of component (A). A content of component (E) of 20 parts by mass or more results in a conductive resin composition with excellent adhesive strength, and a content of component (E) of 300 parts by mass or less results in a conductive resin composition with excellent electrical conductivity. The content of component (E) is preferably 5 to 80% by mass, more preferably 10 to 70% by mass, and most preferably 20 to 60% by mass, per 100% by mass of the total resin components. The content of component (E) may be 20 to 40% by mass, per 100% by mass of the total resin components. A content of component (E) of 5% by mass or more results in excellent adhesive strength and reduced outgassing, and a content of component (E) of 80% by mass or less results in a conductive resin composition with excellent electrical conductivity after curing.

[0059] In addition to the above components, various (meth)acrylates and additives can be added as optional components to the conductive resin composition of the present invention, as long as the effects of the present invention are not impaired. Examples of optional components include (meth)acrylates other than components (A), (B), and (E) (excluding (meth)acrylates having an acidic group and (meth)acrylic group-containing silane coupling agents), 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.

[0060] The conductive resin composition according to the present invention may contain a (meth)acrylate other than the components (A), (B), and (E). These may be used alone or in combination of two or more (two or more). By including a (meth)acrylate other than the components (A), (B), and (E), a conductive resin composition having excellent conductivity in a cured product can be obtained. Considering the reduction of outgassing, the conductive resin composition according to the present invention preferably does not substantially contain a (meth)acrylate other than the components (A), (B), and (E). In this specification, the phrase "substantially does not contain a (meth)acrylate other than the components (A), (B), and (E)" means that the content of a (meth)acrylate other than the components (A), (B), and (E) (excluding (meth)acrylates having an acidic group and (meth)acrylic group-containing silane coupling agents) is 1 part by mass or less per 100 parts by mass of the total of the components (A), (B), and (E). Examples of the (meth)acrylate other than the components (A), (B), and (E) include monofunctional (meth)acrylates and difunctional or higher polyfunctional (meth)acrylates.

[0061] Examples of the monofunctional (meth)acrylate as an optional component include ethyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, isobutyl methacrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, butoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, glycidyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, caprolactone-modified tetrahydrofurfuryl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxy (meth)acrylate, isobornyl (meth)acrylate, and adamantyl (meth)acrylate. acrylate, benzyl (meth)acrylate, phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxytetraethylene glycol (meth)acrylate, nonylphenoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycerol (meth)acrylate, trifluoroethyl (meth)acrylate, morpholinoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, and the like, but are not limited thereto.

[0062] Examples of the polyfunctional (meth)acrylate as an optional component include 1,3-butylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexane glycol di(meth)acrylate, dicyclopentenyl di(meth)acrylate, di(meth)acryloyl isocyanurate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tris((meth)acryloyloxyethyl)isocyanurate, pentaerythritol tetra(meth)acrylate, polyester (meth)acrylate, rubber skeleton-containing (meth)acrylate, siloxane skeleton-containing (meth)acrylate, polycarbonate (meth)acrylate, polybutadiene (meth)acrylate, and (meth)acrylic polymers having a terminal (meth)acrylic group. These may be used alone or in combination of two or more.

[0063] The content of (meth)acrylates other than the above components (A), (B), and (E) (excluding (meth)acrylates having an acidic group) is preferably 0 to 100 parts by mass (more than 0 parts by mass and 100 parts by mass or less), more preferably 0 to 80 parts by mass (more than 0 parts by mass and 80 parts by mass or less), and most preferably 0 to 40 parts by mass (more than 0 parts by mass and 40 parts by mass or less), relative to 100 parts by mass of the above component (A). By having the content of (meth)acrylates other than the above components (A), (B), and (E) (excluding (meth)acrylates having an acidic group and (meth)acrylic group-containing silane coupling agents) in the range of 0 to 100 parts by mass (more than 0 parts by mass and 100 parts by mass or less), a conductive resin composition with excellent electrical conductivity in the cured product can be obtained. When two or more (meth)acrylates other than the components (A), (B), and (E) (excluding (meth)acrylates having an acidic group and (meth)acrylic group-containing silane coupling agents) are used in combination, the content refers to the total amount.

[0064] The conductive resin composition according to the present invention may contain a storage stabilizer. Examples of the storage stabilizer include a polymerization inhibitor and a chelating agent. The polymerization inhibitor can maintain storage stability by capturing generated radical species, and the chelating agent can be used to capture generated metal ions.

[0065] 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 may further include a polymerization inhibitor. 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.

[0066] 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. Examples of chelating agents that are liquid at 25°C include MZ-8 manufactured by Cherest Co., Ltd., but are not limited to these.

[0067] If the amount of storage stabilizer added is too large, the storage stability improves but the reactivity slows down. The content of the storage stabilizer 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 entire conductive resin composition (100 mass % of the conductive resin composition).

[0068] The conductive resin composition according to the present invention may contain an adhesion promoter. The adhesion promoter may include a (meth)acrylate having an acidic group or a silane coupling agent. By including the adhesion promoter, a conductive resin composition having excellent adhesive strength can be obtained. Furthermore, a (meth)acrylate having an acidic group or a (meth)acrylic group-containing silane coupling agent is not included in the resin component described above, and is treated as an adhesion promoter.

[0069] 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. In this specification, the term "(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)acryloxypropyl succinic acid, 4-(meth)acryloxybutyl succinic acid, 2-(meth)acryloxyethyl maleic acid, 3-(meth)acryloxypropyl maleic acid, 4-(meth)acryloxybutyl maleic acid, 2-(meth)acryloxyethyl hexahydrophthalic acid, 3-(meth)acryloxypropyl hexahydrophthalic acid, 4-(meth)acryloxybutyl hexahydrophthalic acid, 2-(meth)acryloxyethyl phthalic acid, 3-(meth)acryloxypropyl phthalic acid, and 4-(meth)acryloxybutyl phthalic acid. Examples of phosphoric acid 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, a conductive resin composition 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. 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.

[0070] 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)acrylic 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.

[0071] The content of the adhesion imparting agent 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 the component (A). The content of the adhesion imparting agent is preferably 0.1 to 1 part by mass, more preferably 0.3 to 0.7 parts by mass, per 100 parts by mass of the resin component. A conductive resin composition with excellent adhesive strength can be obtained by containing the adhesion imparting agent in a range of 0.01 to 10 parts by mass. When two or more adhesion imparting agents are used in combination, the content of the adhesion imparting agents refers to the total amount.

[0072] <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.

[0073] 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.

[0074] <Cured Product> One aspect of the present invention relates to a cured product obtained by curing the conductive resin composition. The cured product can be obtained by applying heat to the conductive resin composition. In one embodiment, the conductive resin composition according to the present invention can be applied to an adherend, and then heat (heat) the conductive resin composition to obtain a cured product.

[0075] <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.

[0076] The conductive resin composition according to the present invention can be cured by applying heat. The heat source used in this process is not particularly limited, and any known heat source, such as a hot air drying oven, can be used.

[0077] 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. The curing time is not particularly limited, but is preferably 10 to 120 minutes, more preferably 30 to 90 minutes, and most preferably 45 to 75 minutes. If the curing time is 10 minutes or more, 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.

[0078] <Applications> 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 conductivity. Because the conductive resin composition according to the present invention can be cured 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, wearables, battery packs, and the like. Examples of plastics that can be used include polypropylene, polyethylene, polyurethane, ABS resin, phenolic resin, CFRP (carbon fiber reinforced plastic), GFRP (glass fiber reinforced plastic), 6,6-nylon, PPS resin, and PBT resin.

[0079] The conductive resin composition according to the present invention and its cured product are preferably used on an adherend whose outermost surface is nickel. The conductive resin composition according to the present invention having the above-described configuration can improve the adhesive strength and the conductivity of the cured product even on an adherend whose outermost surface is nickel that forms an oxide film, although the exact reason is not clear. The adherend whose outermost surface is nickel is not particularly limited, and is mainly nickel-plated, for example, SPCC (cold-rolled steel sheet), stainless steel, or copper components that have been electroplated or electroless plated (electric wires, printed circuit boards, etc.).

[0080] 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, tests were conducted in an environment of 23°C and 50% RH.

[0081] Examples 1 to 5 and Comparative Examples 1 to 3 The following components were prepared to prepare compositions. Component (A): 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: 1600, manufactured by Shin-Nakamura Chemical Co., Ltd.) Component (B): Polyfunctional (meth)acrylate having a skeleton derived from polyalkylene glycol - Bifunctional (meth)acrylate 1 having a skeleton derived from polypropylene glycol (NK Ester 3PG polypropylene glycol dimethacrylate number of repetitions: 3, manufactured by Shin-Nakamura Chemical Co., Ltd.) - Bifunctional (meth)acrylate 2 having a skeleton derived from polypropylene glycol (NK Ester 9PG polypropylene glycol dimethacrylate number of repetitions: 9, manufactured by Shin-Nakamura Chemical Co., Ltd.) - Bifunctional (meth)acrylate 1 having a skeleton derived from polyethylene glycol (NK Ester 3G polyethylene glycol diacrylate number of repetitions: 3, manufactured by Kyoeisha Chemical Co., Ltd.) Bifunctional (meth)acrylate 2 having a skeleton derived from polyethylene glycol (NK Ester 9G polyethylene glycol diacrylate, repeat number: 9, manufactured by Kyoeisha Chemical Co., Ltd.) Component (C): conductive particles Silver particles 1 (Sylbestos TC-508, flake-shaped, 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(D) component: thermal radical generator; organic peroxide (di(4-tert-butylcyclohexyl)peroxydicarbonate, 1-hour half-life temperature: 57.5°C); (E) component: epoxy (meth)acrylate; epoxy acrylate (NK Oligo EA-1010LC, bifunctional (number of acryloyl groups: 2), weight average molecular weight: 400, manufactured by Shin-Nakamura Chemical Co., Ltd.); Optional components: (meth)acrylate 1 other than components (A), (B), and (E) (monofunctional (meth)acrylate IBXA, isobornyl acrylate, manufactured by Osaka Organic Chemical Industry Ltd.); (meth)acrylate 2 other than components (A), (B), and (E) (monofunctional (meth)acrylate NK Ester AM-30PG, methoxytripropylene glycol acrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.); (Meth)acrylate 3 other than components (A), (B), and (E) (bifunctional (meth)acrylate NK ester DCP tricyclodecane dimethanol dimethacrylate manufactured by Shin-Nakamura Chemical Co., Ltd.) (meth)acrylate 4 other than components (A), (B), and (E) (hexafunctional (meth)acrylate NK ester A-DPH dipentaerythritol hexaacrylate manufactured by Shin-Nakamura Chemical Co., Ltd.) adhesion promoter ((meth)acrylate having an acidic group JPA-514 2-hydroxyethyl methacrylate acid phosphate manufactured by Johoku Chemical Industry Co., Ltd.) storage stabilizer (2,6-di-tert-butyl-4-methylphenol (BHT)).

[0082] Compositions of Examples 1 to 5 and Comparative Examples 1 to 3 were prepared. Specifically, component (A), component (B), component (E), and optional components were weighed and charged into a stirring vessel, followed by stirring for 60 minutes. Subsequently, component (C) was weighed and charged into the stirring vessel, followed by stirring for 60 minutes while vacuum degassing. Finally, component (D) was weighed and charged into the stirring vessel, followed by stirring for 60 minutes while vacuum degassing, thereby preparing the compositions of Examples 1 to 5 and Comparative Examples 1 to 3. Detailed preparation amounts (amounts of each component) are shown in Table 1, and all numerical values ​​are in parts by mass.

[0083] <Evaluation of Conductivity> Masking tape (50 μm thick) was applied 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. An adhesive (the composition of Examples 1 to 5 or Comparative Examples 1 to 3) was applied to the exposed surface using a squeegee to form a uniform coating film. The masking tape was then peeled off to prepare test pieces (n=2). Each test piece was 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 x 10 mm wide) on the glass plate. After the temperature of the test piece had cooled to 25°C, the "resistance value (Ω)" was measured by touching each electrode to the cured product with a distance of 50 mm between the electrodes using a dual display multimeter equipped with plate-shaped electrodes. (Resistance value) × (Width of cured product × Thickness of cured product (cross-sectional area)) / (Distance between electrodes) = "Volume resistivity (× 10 －５ The electrical conductivity (Ω·m) was calculated and the value was taken as "electrical conductivity." The results are shown in Table 1. From the viewpoint of ensuring electrical conductivity, the upper limit of electrical conductivity was set to 5.0×10 －５ It is preferable that the resistance is Ω·m or less, and 3.0×10 －５ The lower limit of the electrical conductivity is preferably 0.01×10 －５ It is preferable that the conductivity is Ω·m or more. In Table 1, "-" indicates that the conductivity value was too high and exceeded the measurement limit of the measuring device.

[0084] <Adhesion Strength Evaluation> 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. The composition of Examples 1 to 5 or Comparative Examples 1 to 3 was applied to the exposed surface with a squeegee to form a uniform coating, and then the masking tape was removed. A 2 mm diameter x 1 mm ceramic tip was dropped vertically from 1 cm above the coating surface to prepare test pieces (n=5). The test pieces were heated at 80°C for 60 minutes in a hot air drying oven to cure the composition. After the temperature of the test pieces cooled to room temperature (23°C), 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 this value was taken as the "adhesion strength." The results are shown in Table 1. The lower limit of the adhesive strength is preferably 7.0 MPa or more, more preferably 10.0 MPa or more, and most preferably 12.0 MPa or more. The upper limit of the adhesive strength is not particularly limited, but is preferably 30 MPa or less.

[0085] <Flexibility> The compositions of Examples 1 to 5 or Comparative Examples 1 to 3 were cut into sheets measuring 60 mm in length, 10 mm in width, and 1.0 mm in thickness, and heated at 80°C for 60 minutes to produce cured products. The produced cured products were attached to a jig in tension mode on a dynamic viscoelasticity measuring device DMS6100 manufactured by Hitachi High-Tech Science Corporation, and measurements were made at a frequency of 1 Hz over a temperature range of -50 to 200°C to confirm the "storage modulus (GPa)." The storage modulus at 25°C was recorded and used as "flexibility." From the standpoint of excellent flexibility of the cured product, it is preferable that the "storage modulus (GPa)" be 3.0 GPa or less. There is no particular lower limit for flexibility, but from the standpoint of adhesive strength, it is preferable that it be 0.1 GPa or more.

[0086]

[0087] The cured products of the compositions of Examples 1 to 5 were confirmed to have excellent conductivity, adhesive strength, and flexibility. On the other hand, the composition of Comparative Example 1, which does not contain (A), was confirmed to have poor conductivity and flexibility. Furthermore, the compositions of Comparative Examples 2 and 3, which contain an optional (meth)acrylate other than component (A), component (B), and component (E) instead of component (B), were confirmed to have poor conductivity and flexibility.

[0088] Next, the amount of outgassing of the compositions of the examples was confirmed. The test results are shown in Table 2.

[0089] <Evaluation of Outgassing Amount> 20 mg of the composition of each example was weighed out, and the temperature was raised from 25°C to 80°C at a rate of 10°C / min using a Seiko Instruments Inc. TG / DTA220 thermal weight loss measuring device. Continuous measurement was then performed at 80°C for 1 hour. Starting from the start of the measurement, the "weight loss (%)" was measured after 1 hour at 80°C. This weight loss (%) was considered to be the amount of outgassing. A lower amount of outgassing is preferable because it reduces contamination of electronic components. The upper limit of the amount of outgassing is preferably 0.80% or less, more preferably 0.50% or less, and most preferably 0.45% or less. There is no particular restriction on the lower limit of the amount of outgassing, but it is 0% or more.

[0090]

[0091] The compositions of Examples 1 to 5 all generated low amounts of outgassing, making it possible to reduce contamination of electronic components. It was also confirmed that compositions that did not contain any (meth)acrylate other than component (A), component (B), and component (E), such as the compositions of Examples 1, 4, and 5, generated particularly low amounts of outgassing. Furthermore, it was confirmed that the composition of Example 1, which contained only component (E) and a polyfunctional (meth)acrylate having a skeleton derived from polypropylene glycol as component (B), generated the least amount of outgassing.

[0092] The conductive resin composition of the present invention has excellent conductivity, adhesive strength, and flexibility in the cured product, making it useful for electrical conduction and adhesion applications for the miniaturized electrical and electronic components of recent years. Furthermore, the low amount of outgassing reduces contamination around the cured product, making it particularly useful for applications to electronic components. 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 expanded to a wide range of applications.

[0093] This application is based on Japanese Patent Application No. 2024-112125, 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): a urethane (meth)acrylate having two or more (meth)acryloyl groups in one molecule; component (B): a polyfunctional (meth)acrylate (excluding urethane (meth)acrylate) having a skeleton derived from polyalkylene glycol; component (C): conductive particles; and component (D): a thermal radical generator.

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

3. The conductive resin composition according to claim 1 or 2, further comprising an epoxy (meth)acrylate as component (E).

4. The conductive resin composition according to claim 3, wherein the content of said component (E) is 50 to 250 parts by mass per 100 parts by mass of said component (A).

5. The conductive resin composition according to claim 1 or 2, wherein the component (B) is a polyfunctional (meth)acrylate having a skeleton derived from polypropylene glycol.

6. The conductive resin composition according to claim 1 or 2, wherein the component (B) is a bifunctional (meth)acrylate having a skeleton derived from polyalkylene glycol.

7. The conductive resin composition according to claim 1 or 2, wherein the content of the component (B) is 50 to 500 parts by mass per 100 parts by mass of the component (A).

8. The conductive resin composition according to claim 1 or 2, 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 and less than 3 μm.

9. The conductive resin composition according to claim 3, which is substantially free of any (meth)acrylate other than the components (A), (B) and (E).

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

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