Conductive composition

Abstract

To provide a conductive composition having both excellent conductivity and solvent resistance after curing.SOLUTION: The conductive composition according to an embodiment contains: an epoxy resin (A) containing a solid epoxy resin (A1), a rubber-modified epoxy resin (A2), and a liquid alicyclic epoxy resin (A3) having a glycidyl ether group; conductive particles (B); a blocked polyisocyanate curing agent (C); and an imidazole-based curing aid (D). The amount of the solid epoxy resin (A1) is 6-18 pts.mass and the total amount of the rubber-modified epoxy resin (A2) and the liquid alicyclic epoxy resin (A3) is 42-94 pts.mass based on 100 pts.mass of the epoxy resin (A). The amount of the conductive particles (B) is 1,100-2,400 pts.mass, the amount of the blocked polyisocyanate curing agent (C) is 40-120 pts.mass, and the amount of the imidazole-based curing aid (D) is 2-12 pts.mass.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an electrically conductive composition. [Background technology]

[0002] BACKGROUND ART A conductive paste (conductive composition) for printing containing conductive particles and an epoxy resin is known for forming a conductive pattern on a printed wiring board.

[0003] Patent Document 1 describes a conductive composition containing an epoxy compound, an acid anhydride, an organometallic complex, and nickel powder and / or silver-plated powder, and lists examples of epoxy compounds such as rubber-modified epoxy resin and cyclohexanedimethyldiglycidyl ether. Patent Document 2 also discloses a conductive epoxy adhesive containing a reaction product of a flexible polyepoxide resin having a predetermined hardness, a curing agent containing an amine-terminated butadiene-acrylonitrile polymer, and a conductive filler. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-256539 [Patent Document 2] Japanese Patent Application Publication No. 10-95966 Summary of the Invention [Problem to be solved by the invention]

[0005] Although conventional conductive compositions have excellent conductivity, for example, when used to form a conductor pattern on a printed wiring board, if the conductor pattern, which is a coating film after curing, is wiped with an organic solvent such as an acetate-based solvent, the conductor pattern may be wiped off by the solvent. The above patent document lists rubber-modified epoxy resins and cyclohexane dimethyl diglycidyl ether as examples of epoxy resins to be blended into the conductive composition, but does not mention that excellent conductivity and solvent resistance can be achieved by using a rubber-modified epoxy resin in combination with an alicyclic epoxy resin having a glycidyl ether group.

[0006] An object of an embodiment of the present invention is to provide a conductive composition that has both excellent electrical conductivity and solvent resistance after curing. [Means for solving the problem]

[0007] The present invention includes the embodiments shown below. [1] An epoxy resin (A) including a solid epoxy resin (A1), a rubber-modified epoxy resin (A2), and a liquid alicyclic epoxy resin (A3) having a glycidyl ether group; conductive particles (B), A blocked polyisocyanate curing agent (C), and Imidazole curing aid (D), An electrically conductive composition comprising: a conductive composition, wherein, relative to 100 parts by mass of the epoxy resin (A), the amount of the solid epoxy resin (A1) is 6 to 18 parts by mass, the total amount of the rubber-modified epoxy resin (A2) and the liquid alicyclic epoxy resin (A3) is 42 to 94 parts by mass, the amount of the conductive particles (B) is 1100 to 2400 parts by mass, the amount of the blocked polyisocyanate curing agent (C) is 40 to 120 parts by mass, and the amount of the imidazole-based curing aid (D) is 2 to 12 parts by mass.

[0008] [2] The conductive composition according to [1], wherein the mass ratio (A2) / (A3) of the rubber-modified epoxy resin (A2) to the liquid alicyclic epoxy resin (A3) is 5 / 95 to 80 / 20. [3] The conductive composition according to [1] or [2], wherein the conductive composition has a reaction initiation temperature of 125 to 135°C. [4] The conductive composition according to any one of [1] to [3], wherein the liquid alicyclic epoxy resin (A3) contains a dicyclopentadiene-type epoxy resin having a glycidyl ether group. [5] The conductive composition according to any one of [1] to [4], wherein the conductive composition has a viscosity of 30 to 100 Pa·s at 25°C. [6] The conductive composition according to any one of [1] to [5], wherein the conductive particles (B) contain silver-coated copper particles. [Effects of the Invention]

[0009] The conductive composition according to the embodiment of the present invention provides excellent conductivity and solvent resistance after curing. DETAILED DESCRIPTION OF THE INVENTION

[0010] The conductive composition according to this embodiment is a thermosetting conductive composition comprising an epoxy resin (A) containing a solid epoxy resin (A1), a rubber-modified epoxy resin (A2), and a liquid alicyclic epoxy resin (A3) having a glycidyl ether group; conductive particles (B); a blocked polyisocyanate curing agent (C); and an imidazole-based curing aid (D). Because the conductive composition contains an epoxy resin, it is also referred to as a conductive resin composition. Here, the term "solid" refers to an epoxy resin that is not fluid at room temperature (25°C) in a solvent-free state. The term "liquid" refers to an epoxy resin that is fluid at room temperature (25°C) in a solvent-free state. The term "epoxy resin" is a general term for compounds containing epoxy groups within the molecule, and is used to encompass not only polymers or prepolymers but also epoxy compounds as monomers.

[0011] The solid epoxy resin (A1) is a compound containing at least one epoxy group in the molecule, and is not particularly limited as long as it is solid at room temperature (25°C), and various known resins can be used. Specific examples of the solid epoxy resin (A1) include bisphenol-type solid epoxy resins such as bisphenol A-type solid epoxy resins, bisphenol F-type solid epoxy resins, and bisphenol S-type solid epoxy resins, spirocyclic-type solid epoxy resins, naphthalene-type solid epoxy resins, biphenyl-type solid epoxy resins, terpene-type solid epoxy resins, trisphenolmethane-type solid epoxy resins, glycidylamine-type solid epoxy resins, and novolac-type solid epoxy resins. These resins may be used alone or in combination of two or more. The solid epoxy resin (A1) may be used by dissolving it in a solvent (E) described below.

[0012] The epoxy equivalent of the solid epoxy resin (A1) is not particularly limited, and is, for example, preferably 1000 to 10000 g / eq, and more preferably 3000 to 10000 g / eq.

[0013] In this specification, the epoxy equivalent of an epoxy resin refers to the mass of a resin containing one equivalent of epoxy groups, measured in accordance with JIS K7236:2009, which was created based on ISO 3001 Plastics—Epoxy compounds—Determination of epoxy equivalent.

[0014] The rubber-modified epoxy resin (A2) is not particularly limited as long as it is a compound having at least one epoxy group in the molecule and containing a structure derived from rubber, and various known compounds can be used. For example, a compound obtained by reacting an epoxy resin with rubber can be used as the rubber-modified epoxy resin (A2).

[0015] Examples of rubber include natural rubber, acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), butadiene rubber (BR), acrylic rubber (ACM), and butyl rubber (IIR). These may be used alone or in combination of two or more. In terms of reactivity with epoxy resins, these rubbers may have a functional group at their terminal that can react with epoxy groups, such as an amino group, a hydroxyl group, or a carboxyl group. In this specification, the above-listed rubbers are used as a concept that also encompasses those having these functional groups at their terminals.

[0016] The epoxy resin to be reacted with rubber is not particularly limited as long as it is a compound having at least one epoxy group, and examples thereof include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin, spiro ring type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, terpene type epoxy resin, trisphenolmethane type epoxy resin, glycidylamine type epoxy resin, novolac type epoxy resin, etc. Any of these may be used alone or in combination of two or more.

[0017] As the rubber-modified epoxy resin (A2), from the viewpoint of better solvent resistance, among the above, an epoxy resin modified with acrylonitrile butadiene rubber (that is, an NBR-modified epoxy resin) is preferred.

[0018] Commercially available rubber-modified epoxy resins (A2) may be used, such as ADEKA RESIN® EPR4030 manufactured by ADEKA CORPORATION, EPICLON® TSR-960 manufactured by DIC Corporation, and Hypox RA840 manufactured by Huntsman. These products may contain unreacted liquid epoxy resin, which corresponds to component (A4) described below. For example, when using an NBR-modified epoxy resin, which is a reaction product of bisphenol A liquid epoxy resin and NBR, a mixture of the NBR-modified epoxy resin and unreacted bisphenol A liquid epoxy resin may be blended. In this case, the NBR-modified epoxy resin corresponds to component (A2), and the unreacted bisphenol A liquid epoxy resin corresponds to component (A4).

[0019] The rubber-modified epoxy resin (A2) may be liquid or solid at room temperature (25°C), however, even if the rubber-modified epoxy resin (A) is solid, it is not included in the component (A1).

[0020] The epoxy equivalent of the rubber-modified epoxy resin (A2) is not particularly limited, and may be, for example, 100 to 800 g / eq, or 200 to 600 g / eq.

[0021] The liquid alicyclic epoxy resin (A3) having a glycidyl ether group is an alicyclic compound having at least two glycidyl ether groups ((C2H3O)-CH2-O-) in the molecule, and is not particularly limited as long as it is liquid at room temperature (25°C), and various known compounds can be used. Examples of the liquid alicyclic epoxy resin (A3) include tricyclo[5.2.1.0 2,6 ] Examples thereof include decanedimethanol diglycidyl ether (also known as dicyclopentadiene dimethanol diglycidyl ether), cyclohexanedimethanol diglycidyl ether, and the like.

[0022] Among these, the liquid alicyclic epoxy resin (A3) is preferably one having a dicyclopentadiene structure together with a glycidyl ether group, i.e., a dicyclopentadiene type epoxy resin having a glycidyl ether group, such as tricyclo[5.2.1.0 2,6 ] decanedimethanol diglycidyl ether. The liquid alicyclic epoxy resin (A3) preferably contains the above dicyclopentadiene type epoxy resin in an amount of 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, and may contain 100% by mass.

[0023] The epoxy equivalent of the liquid alicyclic epoxy resin (A3) is not particularly limited, and may be, for example, 70 to 300 g / eq, or 150 to 250 g / eq.

[0024] The epoxy resin (A) may be composed solely of the solid epoxy resin (A1), rubber-modified epoxy resin (A2), and liquid alicyclic epoxy resin (A3) described above, or may contain other liquid epoxy resins (A4) as optional components. The liquid epoxy resin (A4) is not particularly limited, and examples thereof include bisphenol-type liquid epoxy resins, spirocyclic-type liquid epoxy resins, naphthalene-type liquid epoxy resins, biphenyl-type liquid epoxy resins, terpene-type liquid epoxy resins, trisphenolmethane-type liquid epoxy resins, glycidylamine-type liquid epoxy resins, novolac-type liquid epoxy resins, and liquid alicyclic epoxy resins other than component (A3). These may be used alone or in combination of two or more.

[0025] The amount of solid epoxy resin (A1) in 100 parts by mass of epoxy resin (A) is 6 to 18 parts by mass. When the amount of solid epoxy resin (A1) is 6 parts by mass or more, it is possible to improve solvent resistance after curing. When the amount of solid epoxy resin (A1) is 18 parts by mass or less, it is possible to improve conductivity and also reduce the viscosity of the conductive composition, thereby improving processability. The amount of solid epoxy resin (A1) is more preferably 8 to 16 parts by mass, and even more preferably 10 to 15 parts by mass.

[0026] The total amount (A2+A3) of the rubber-modified epoxy resin (A2) and the liquid alicyclic epoxy resin (A3) per 100 parts by mass of the epoxy resin (A) is 42 to 94 parts by mass. By making this total amount (A2+A3) 42 to 94 parts by mass, it is possible to improve solvent resistance after curing. The total amount (A2+A3) is more preferably 47 to 81 parts by mass, more preferably 50 to 75 parts by mass, and even more preferably 55 to 72 parts by mass.

[0027] The mass ratio (A2) / (A3) of the rubber-modified epoxy resin (A2) to the liquid alicyclic epoxy resin (A3) is preferably 5 / 95 to 80 / 20. This can enhance the effect of improving solvent resistance after curing. The mass ratio (A2) / (A3) is more preferably 9 / 91 to 70 / 30, more preferably 15 / 85 to 50 / 50, and even more preferably 20 / 80 to 40 / 60.

[0028] The amount of the rubber-modified epoxy resin (A2) in 100 parts by mass of the epoxy resin (A) is not particularly limited, but is preferably 5 to 35 parts by mass, more preferably 7 to 30 parts by mass, and even more preferably 10 to 25 parts by mass.

[0029] The amount of the liquid alicyclic epoxy resin (A3) in 100 parts by mass of the epoxy resin (A) is not particularly limited, but is preferably 15 to 80 parts by mass, more preferably 17 to 74 parts by mass, and even more preferably 35 to 60 parts by mass.

[0030] The total amount (A1+A2+A3) of the solid epoxy resin (A1), the rubber-modified epoxy resin (A2), and the liquid alicyclic epoxy resin (A3) in 100 parts by mass of the epoxy resin (A) is not particularly limited, but is preferably 50 to 100 parts by mass, more preferably 60 to 95 parts by mass, and even more preferably 65 to 90 parts by mass.

[0031] The conductive particles (B) are not particularly limited as long as they are particles having conductivity, and examples thereof include conductive metal particles such as copper particles, silver particles, nickel particles, silver-coated copper particles, gold-coated copper particles, silver-coated nickel particles, gold-coated nickel particles, and silver-coated copper alloy particles, and these may be used alone or in combination of two or more types.

[0032] The conductive particles (B) are preferably at least one selected from the group consisting of silver particles, silver-coated copper particles, and silver-coated copper alloy particles. The silver-coated copper particles are not particularly limited as long as they have copper particles and a silver-containing layer that coats at least a portion of the copper particles. The silver-coated copper alloy particles are not particularly limited as long as they have copper alloy particles and a silver-containing layer that coats at least a portion of the copper alloy particles. The content ratio of the silver-containing layer in the silver-coated copper particles and silver-coated copper alloy particles is not particularly limited and may be, for example, 4 to 24 mass%. The silver content in the silver-containing layer is not particularly limited and may be, for example, 90 to 100 mass%. The copper alloy particles may contain, for example, 0.5 to 25 mass% zinc and / or 0.5 to 30 mass% nickel, with the balance being copper, and the balance of copper may contain unavoidable impurities.

[0033] The shape of the conductive particles (B) is not particularly limited, and for example, spherical, flake (scale-like), dendritic, or fibrous particles can be used. Preferably, spherical particles are used.

[0034] The average particle size of the conductive particles (B) is not particularly limited, but is preferably 1 to 20 μm. When the average particle size of the conductive particles (B) is 1 μm or more, the dispersibility of the conductive particles (B) is improved, and aggregation can be prevented. When the average particle size of the conductive particles (B) is 20 μm or less, excellent conductivity is easily obtained.

[0035] In this specification, the term "average particle diameter of the conductive particles (B)" refers to the number-based average particle diameter D50 (median diameter) measured by a laser diffraction / scattering method.

[0036] The content of the conductive particles (B) is 1100 to 2400 parts by mass relative to 100 parts by mass of the epoxy resin (A). When the amount of the conductive particles (B) is 1100 parts by mass or more, the conductivity can be improved, and when the amount is 2400 parts by mass or less, the solvent resistance after curing can be improved. The content of the conductive particles (B) is more preferably 1200 to 2300 parts by mass, and even more preferably 1300 to 2200 parts by mass.

[0037] The blocked polyisocyanate curing agent (C) is a polyisocyanate that has been blocked with a blocking agent.

[0038] Examples of polyisocyanates include aliphatic diisocyanates such as hexamethylene diisocyanate (including trimer), tetramethylene diisocyanate, and trimethylhexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and 4,4'-methylenebis(cyclohexyl isocyanate); aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, and xylylene diisocyanate; and modified products of these diisocyanates (e.g., urethane-modified products, carbodiimide-, uretdione-, uretonimine-, biuret-, and / or isocyanurate-modified products). These may be used alone or in combination of two or more.

[0039] Examples of the sealing agent include monohydric alkyl (or aromatic) alcohols such as n-butanol, n-hexyl alcohol, 2-ethylhexanol, lauryl alcohol, phenol carbinol, and methylphenyl carbinol; cellosolves such as ethylene glycol monohexyl ether and ethylene glycol mono 2-ethylhexyl ether; polyether-type double-ended diols such as polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol phenol; polyester-type double-ended polyols obtained from diols such as ethylene glycol, propylene glycol, and 1,4-butanediol and dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, suberic acid, and sebacic acid; phenols such as para-t-butylphenol and cresol; and oximes such as dimethyl ketoxime, methyl ethyl ketoxime, methyl isobutyl ketoxime, methyl amyl ketoxime, and cyclohexanone oxime; and lactams typified by ε-caprolactam and γ-butyrolactam. These may be used alone or in combination of two or more.

[0040] The isocyanate content (NCO%) of the blocked polyisocyanate curing agent (C) is not particularly limited and is, for example, preferably 6 to 15 mass%, more preferably 8 to 12 mass%. Here, the NCO% is calculated by the following formula, using a measurement sample obtained by dissociating the blocking agent from the blocked polyisocyanate curing agent (C) by heating or the like, neutralizing the isocyanate groups in the measurement sample with an excess of 2N amine, and then determining the NCO content (mass%) of the measurement sample by back titration with 1N hydrochloric acid. NCO% = {(mass of measurement sample) × (NCO content of measurement sample)} / (mass of blocked polyisocyanate)

[0041] Examples of such blocked polyisocyanate curing agents (C) that can be used include "Duranate MF-K60B" (NCO%: 6.5% by mass), "Duranate SBN-70D" (NCO%: 10.1% by mass), "Duranate TBN-75PS" (NCO%: 10.7% by mass), "Duranate SBB-70P" (NCO%: 10.1% by mass), "Duranate SBL-100" (NCO%: 15.0% by mass), "Duranate MF-B60B" (NCO%: 8.0% by mass), "Duranate 17B-60P" (NCO%: 9.5% by mass), "Duranate TPA-B80E" (NCO%: 12.5% ​​by mass), and "Duranate E402-B80B" (NCO%: 6.0% by mass) (all manufactured by Asahi Kasei Corporation).

[0042] The content of the blocked polyisocyanate curing agent (C) is 40 to 120 parts by mass relative to 100 parts by mass of the epoxy resin (A). When the content of the blocked polyisocyanate curing agent (C) is 40 parts by mass or more, the solvent resistance and electrical conductivity after curing can be improved, and when it is 120 parts by mass or less, the electrical conductivity can be improved. The content of the blocked polyisocyanate curing agent (C) is more preferably 50 to 110 parts by mass, and even more preferably 55 to 100 parts by mass.

[0043] Examples of the imidazole-based curing aid (D) include imidazoles and their salts. Specific examples of imidazoles include alkylimidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-propylimidazole, 2-butylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, and 2-ethyl-4-methylimidazole; and arylimidazoles or aralkylimidazoles such as 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, and 1-benzyl-2-methylimidazole. Examples of imidazole salts include organic salts, such as formates, phenol salts, and phenol novolac salts, and carbonates of the above imidazoles. These may be used alone or in combination.

[0044] From the viewpoints of solvent resistance and electrical conductivity, the imidazole curing aid (D) is preferably an alkylimidazole, more preferably one having a linear carbon chain structure. The linear carbon chain is preferably bonded to the 2-position of the imidazole ring. The linear carbon chain structure preferably has 2 to 15 carbon atoms, more preferably 5 to 13, and even more preferably 10 to 12 carbon atoms.

[0045] The content of the imidazole curing aid (D) is 2 to 12 parts by mass relative to 100 parts by mass of the epoxy resin (A). When the content of the imidazole curing aid (D) is 2 parts by mass or more, the solvent resistance after curing can be improved, and when it is 12 parts by mass or less, the conductivity can be improved. The content of the imidazole curing aid (D) is more preferably 3 to 10 parts by mass, and even more preferably 3 to 8 parts by mass.

[0046] The conductive composition according to this embodiment may contain a solvent (E). Examples of the solvent (E) include glycol ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, triethylene glycol dimethyl ether, dipropylene glycol monomethyl ether, and dipropylene glycol dimethyl ether; alcohols such as terpineol, 2,2,4-trimethylpentane-1,3-diol monoisobutyrate, dihydroterpineol, and benzyl alcohol; esters such as propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, and diethylene glycol monoethyl ether acetate; and γ-butyrolactone. These solvents may be used alone or in combination of two or more.

[0047] The content of the solvent (E) is not particularly limited, and may be, for example, 5 to 200 parts by mass, 10 to 150 parts by mass, or 20 to 100 parts by mass relative to 100 parts by mass of the epoxy resin (A).

[0048] In addition to the above components, the conductive composition according to this embodiment may also contain additives that have been conventionally added to similar conductive compositions within the scope of the present embodiment, such as antifoaming agents, thickeners, tackifiers, fillers, anti-settling agents, colorants, antioxidants, plasticizers, ultraviolet absorbers, and flame retardants.

[0049] The conductive composition according to this embodiment can be obtained by blending and thoroughly mixing the above-described components in predetermined amounts.

[0050] The conductive composition of this embodiment preferably has a reaction initiation temperature of 125 to 135°C, thereby further improving solvent resistance. The reaction initiation temperature of the conductive composition is more preferably 127 to 134°C, and even more preferably 129 to 133°C. The reaction initiation temperature of the conductive composition can be adjusted, for example, by the type of imidazole-based curing aid (D). The method for measuring the reaction initiation temperature is as described in the Examples section.

[0051] The conductive composition of this embodiment preferably has a viscosity of 30 to 100 Pa·s at a liquid temperature of 25°C from the viewpoint of processability, particularly screen printability. A viscosity of 30 Pa·s or more can suppress bleeding of the coating film and improve plate release from the screen printing plate. A viscosity of 100 Pa·s or less can suppress peeling of the coating film and promote leveling. The viscosity of the conductive composition is more preferably 30 to 90 Pa·s, more preferably 40 to 80 Pa·s, and even more preferably 50 to 75 Pa·s. The viscosity can be measured as described in the Examples section.

[0052] The use of the conductive composition according to this embodiment is not particularly limited, and it can be used in various applications where conductivity is required. Preferably, it is used as a conductive paste for forming a conductor pattern of a printed wiring board, and is preferably used as a conductive paste for printing such as screen printing. [Example]

[0053] Examples of the present invention will be described below, but the present invention is not limited to these examples. In the following, the blending ratios and the like are based on mass unless otherwise specified.

[0054] Conductive compositions were prepared by mixing the components according to the formulations (parts by mass) shown in Tables 1 to 7 below. In the tables, the "amount of component (A2) (parts by mass)" refers to the parts by mass of the rubber-modified epoxy resin (A2) relative to 100 parts by mass of the epoxy resin (A). The "amount (A2+A3) (parts by mass)" refers to the total parts by mass of the rubber-modified epoxy resin (A2) and the liquid alicyclic epoxy resin (A3) relative to 100 parts by mass of the epoxy resin (A). The "(A2) / (A3) mass ratio" refers to the mass ratio of the rubber-modified epoxy resin (A2) to the liquid alicyclic epoxy resin (A3). Details of each component in the tables are as follows:

[0055] Solid epoxy resin: Bisphenol A type solid epoxy resin, DIC Corporation "HM-101", epoxy equivalent = 7500-8500g / eq

[0056] Liquid epoxy resin 1: A mixture containing a rubber-modified epoxy resin obtained by modifying a bisphenol A type epoxy resin with nitrile rubber. ADEKA Corporation, "ADEKA RESIN (registered trademark) EPR-4030" (40% by mass of NBR-modified epoxy resin, 60% by mass of bisphenol A type epoxy resin)

[0057] Liquid epoxy resin 2: Dicyclopentadiene dimethanol diglycidyl ether represented by the following formula (1), "EP-4088L" manufactured by ADEKA Corporation, epoxy equivalent = 170 g / eq Liquid epoxy resin 3: a liquid alicyclic epoxy resin represented by the following formula (2), "Epocalic (registered trademark) THI-DE" manufactured by Eneos Corporation Liquid epoxy resin 4: Liquid alicyclic epoxy resin represented by the following formula (3), "CELLOXIDE 2021P" manufactured by Daicel Corporation Liquid epoxy resin 5: a liquid alicyclic epoxy resin represented by the following formula (4), "CELLOXIDE 8000" manufactured by Daicel Corporation Liquid epoxy resin 6: a glycidylamine-type liquid epoxy resin represented by the following formula (5), "jER630" manufactured by Mitsubishi Chemical Corporation Liquid epoxy resin 7: a glycidyl ether type liquid epoxy resin represented by the following formula (6), "Epogose (registered trademark) HD(D)" manufactured by Yokkaichi Synthetic Co., Ltd. [ka]

[0058] ·Conductive particles: Spherical 10% silver-coated copper particles with an average particle size of 5 μm Isocyanate curing agent: Blocked polyisocyanate solution of hexamethylene diisocyanate (solid content: 70% by mass, NCO%: 10.1% by mass, solvent: PMA), "Duranate SBB-70P" manufactured by Asahi Kasei Corporation. The amount of isocyanate curing agent in the table is the mass part of the solid content, which is the active ingredient, and the amount of solvent PMA is included in the amount of "Solvent 2" in the table.

[0059] Imidazole curing aid: Shikoku Chemicals Corporation "C11Z", 2-undecylimidazole Thermal acid generator: "SI-110" manufactured by Sanshin Chemical Industry Co., Ltd., benzyl (4-hydroxyphenyl) (methyl) sulfonium hexafluorophosphate Amine curing aid: Ajinomoto Fine-Techno Co., Ltd. "PN-H", epoxy resin amine adduct Solvent 1: Butyl carbitol Solvent 2: Propylene glycol monomethyl ether acetate (PMA)

[0060] The volume resistivity, solvent resistance, and viscosity of the obtained conductive compositions were measured. For Example 3 and Comparative Examples 14 and 15, the reaction initiation temperature was also measured. The results are shown in Tables 1 to 7. The measurement methods are as follows.

[0061] [Volume resistivity] A 290-mesh stainless steel screen printing plate was used to screen print (length 100 mm, width 0.8 mm) on a 188-μm-thick PET film, and the film was then heat-cured at 130°C for 30 minutes to form a pattern. The resistance (R) between both ends of the pattern was then measured using a tester, and the cross-sectional area (S, cm2 The volume resistivity was calculated from the mass (μm) and length (L, cm) using the following formula (I). -4 A value of less than Ω·cm was considered to be excellent in conductivity. Volume resistivity = (S / L) x R (I)

[0062] [Solvent resistance] The pattern formed in the measurement of volume resistivity was subjected to a rubbing test using "Solfit AC" (3-methoxy-3-methyl-1-butyl acetate) manufactured by Kuraray Co., Ltd. as a solvent. Specifically, a cloth cloth was soaked in the solvent, and the pattern was rubbed back and forth 10 times, after which the solvent was wiped off with a dry cloth cloth. After the rubbing test, the volume resistivity was measured in the same manner as above. The increase in volume resistivity after the rubbing test relative to the volume resistivity before the rubbing test was calculated as the resistance change rate, and the solvent resistance was evaluated according to the following criteria. ◎: Resistance change rate is 5% or less ○: Resistance change rate is greater than 5% and less than 10% △: Resistance change rate is greater than 10% and less than 20% ×: Resistance change rate is greater than 20%

[0063] [viscosity] The viscosity of the conductive composition was measured using a Brookfield E-type viscometer (cone plate) with a CPA-52Z spindle, at a measurement temperature of 25° C. and a rotation speed of 5 rpm.

[0064] [Reaction start temperature] The conductive composition was heated from 25°C to 250°C at a rate of 10°C / min in a nitrogen atmosphere using a differential scanning calorimeter (Perkin Elmer "DSC4000") to obtain a DSC curve. The extrapolated onset temperature was determined from the obtained DSC curve and used as the reaction onset temperature. Specifically, for the rising portion of the DSC curve, the point where the extrapolations of the base portion before the rise and the rising portion intersect was determined as the extrapolated onset point (extrapolated onset temperature).

[0065] [Table 1]

[0066] [Table 2]

[0067] [Table 3]

[0068] [Table 4]

[0069] [Table 5]

[0070] [Table 6]

[0071] [Table 7]

[0072] As shown in Table 1, Comparative Example 1 is an example in which the content of the solid epoxy resin (A1) exceeded the upper limit, and the electrical conductivity was poor, and the viscosity was high and the processability was poor. Comparative Examples 2 and 3 are examples in which the content of the solid epoxy resin (A1) was less than the lower limit, and the solvent resistance was poor. In contrast, Examples 1 to 3, in which the content of the solid epoxy resin (A1) fell within the specified range, were excellent in electrical conductivity and solvent resistance.

[0073] As shown in Table 2, Comparative Example 4, which did not contain the rubber-modified epoxy resin (A2), and Comparative Example 5, which did not contain the liquid alicyclic epoxy resin (A3), were inferior in solvent resistance. In contrast, Examples 4 to 7, which used the rubber-modified epoxy resin (A2) and the liquid alicyclic epoxy resin (A3) in combination and whose total content (A2+A3) fell within the specified range, were able to improve solvent resistance while maintaining excellent electrical conductivity.

[0074] As shown in Table 3, Comparative Examples 6 to 8, which used alicyclic liquid epoxy resins 3 to 5 in which epoxy groups were directly bonded to the cyclohexane ring instead of the liquid alicyclic epoxy resin (A3) having a glycidyl ether group, showed inferior solvent resistance compared to Example 3. Comparative Examples 9 and 10, which used non-alicyclic liquid epoxy resins 6 and 7, which had glycidyl ether groups but were not alicyclic, also showed inferior solvent resistance compared to Example 3. This shows that the liquid alicyclic epoxy resin (A3) having a glycidyl ether group is suitable as a liquid epoxy resin to be used in combination with the solid epoxy resin (A1) and the rubber-modified epoxy resin (A2).

[0075] As shown in Table 4, Comparative Example 11 is an example in which the content of the blocked polyisocyanate curing agent (C) was less than the lower limit, and the electrical conductivity and solvent resistance were poor. Comparative Examples 12 and 13 are examples in which the content of the blocked polyisocyanate curing agent (C) exceeded the upper limit, and the electrical conductivity was poor. In contrast, Examples 8 to 11, in which the content of the blocked polyisocyanate curing agent (C) fell within the specified range, were excellent in both electrical conductivity and solvent resistance.

[0076] As shown in Table 5, Comparative Example 14 is an example in which a thermal acid generator was used as the curing aid, and Comparative Example 15 is an example in which an amine-based curing aid was used as the curing aid, and both were poor in solvent resistance. This shows that by using an imidazole-based curing aid as the curing aid together with the above-mentioned epoxy resin (A) and blocked polyisocyanate curing agent (C), it is possible to achieve both electrical conductivity and solvent resistance.

[0077] As shown in Table 6, Comparative Examples 16 and 17 were examples in which the content of the imidazole-based curing aid was below the lower limit, and therefore had poor solvent resistance. Comparative Example 18 was an example in which the content of the imidazole-based curing aid exceeded the upper limit, and therefore had poor conductivity. In contrast, Examples 3 and 12 to 14, in which the content of the imidazole-based curing aid fell within the specified range, had excellent conductivity and solvent resistance.

[0078] As shown in Table 7, Comparative Examples 19 to 21 are examples in which the content of conductive particles was below the lower limit and therefore had poor conductivity. Comparative Example 22 is an example in which the content of conductive particles exceeded the upper limit and therefore had poor solvent resistance. In contrast, Examples 3, 15, and 16, in which the content of conductive particles fell within the specified range, had excellent conductivity and solvent resistance.

[0079] The various numerical ranges described in this specification can be arbitrarily combined with their upper and lower limits, and all such combinations are considered to be preferred numerical ranges described in this specification. Furthermore, a numerical range described as "X to Y" means from X to Y.

Claims

1. an epoxy resin (A) containing a solid epoxy resin (A1), a rubber-modified epoxy resin (A2), and a liquid alicyclic epoxy resin (A3) having a glycidyl ether group; conductive particles (B), A blocked polyisocyanate curing agent (C), and imidazole-based curing aid (D), An electrically conductive composition comprising: a conductive composition in which, relative to 100 parts by mass of the epoxy resin (A), the amount of the solid epoxy resin (A1) is 6 to 18 parts by mass, the total amount of the rubber-modified epoxy resin (A2) and the liquid alicyclic epoxy resin (A3) is 42 to 94 parts by mass, the amount of the conductive particles (B) is 1,100 to 2,400 parts by mass, the amount of the blocked polyisocyanate curing agent (C) is 40 to 120 parts by mass, and the amount of the imidazole-based curing aid (D) is 2 to 12 parts by mass.

2. 2. The conductive composition according to claim 1, wherein the mass ratio (A2) / (A3) of the rubber-modified epoxy resin (A2) to the liquid alicyclic epoxy resin (A3) is 5 / 95 to 80 / 20.

3. 3. The conductive composition according to claim 1, wherein the conductive composition has a reaction initiation temperature of 125 to 135°C.

4. The conductive composition according to claim 1 or 2, wherein the liquid alicyclic epoxy resin (A3) comprises a dicyclopentadiene-type epoxy resin having a glycidyl ether group.

5. 3. The conductive composition according to claim 1, wherein the conductive composition has a viscosity of 30 to 100 Pa·s at 25°C.

6. The conductive composition according to claim 1 or 2, wherein the conductive particles (B) comprise silver-coated copper particles.

Images