JP2019143094A - Conductive coating composition and conductive coating film - Google Patents

Abstract

To provide a conductive coating composition and a conductive coating film which require no high temperature (for example, approximately 150°C) in which a resin substrate having a low melting point is deformed in forming a coating film, have excellent adhesiveness to various substrates including a polyolefin resin substrate, have high stretchability exceeding 200%, have excellent conductivity at the time of high elongation and after expansion and contraction and are not reduced in conductivity even when expansion and contraction are repeated below the freezing point.SOLUTION: There is provided a conductive coating composition comprising an acid-modified synthetic rubber, a crosslinking agent and a conductive material.SELECTED DRAWING: None

Description

  The present invention relates to a conductive film excellent in stretchability and a conductive paint capable of forming the film.

  In recent years, efforts toward the popularization of devices that require flexibility and stretchability, such as wearable devices, flexible printed circuit boards, and displays, have become active. In these devices, a technique using a circuit board or a sensor in which a conductive film having elasticity is formed in a necessary pattern by printing or the like on a base material having flexibility or elasticity has attracted attention.

  As the base material having flexibility and stretchability, a silicone resin base material is often used from the viewpoint of flexibility, and a polyurethane resin base material is often used from the viewpoint of flexibility and cost. Polyolefin is used from the viewpoint of chemical stability and cost. Application to resin base materials is expected.

  As a conductive film having stretchability, many techniques for applying a paint containing a conductive material to a stretchable binder have been proposed. For example, Patent Document 1 discloses a conductive paste containing a conductive material in a rubber component crosslinked (vulcanized) with sulfur, and Patent Document 2 contains a conductive material in a resin containing a hydroxyl group and a silanol-based crosslinking agent. As the conductive paste, Patent Document 3 proposes a conductive paste containing a conductive material in urethane resin.

Table 2015/005204 Japanese Patent Laid-Open No. 2006-207377 JP 2013-131385 A

  However, the sulfur-cured vulcanized rubber binder described in Patent Document 1 performs a high-temperature treatment at about 150 ° C. when the rubber is crosslinked (vulcanized) to form a film. When such a low melting point resin is used for the base material, the base material may be deformed, and the applicable base material resin is limited. Also in Patent Document 2, drying at 170 ° C. is necessary at the time of forming a film, and as in Patent Document 1, applicable substrates are limited. The conductive paste described in Patent Document 3 has a problem in adhesion with a polyolefin resin substrate. Not only these patent documents 1-3, but the conductive coating material which has sufficient adhesiveness with a polyolefin resin base material has not been seen until now.

  In addition, the conductive coatings described in Patent Documents 1 to 3 are electrically conductive in a highly stretched state (stretched state) exceeding 80% elongation and stretchable (stretched) exceeding 200%. Thus, the properties of returning to the original dimensions) and the conductivity after expansion and contraction are insufficient, and improvement in these properties is desired. Further, the conventional conductive film has a problem that the conductivity deteriorates when the expansion and contraction is repeated under a sub-freezing environment.

  In order to solve the above problems, the present invention does not require a high temperature of about 150 ° C. for film formation, has excellent adhesion to various substrates such as polyolefin resin substrates, and 200%. A conductive paint and a conductive film that have high stretchability exceeding the above, have excellent electrical conductivity at the time of high elongation and after stretching, and do not decrease in conductivity even when stretched repeatedly below freezing point. The issue is to provide.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by using a specific synthetic rubber and a crosslinking agent as a binder component, and have reached the present invention.

That is, the gist of the present invention is as follows.
An electrically conductive paint characterized by containing an acid-modified synthetic rubber, a crosslinking agent, and an electrically conductive material. The conductive film is a film derived from the conductive paint.

  The conductive paint and conductive film of the present invention do not require a high temperature (for example, about 150 ° C.) such that the low melting point resin base material is deformed during the film formation, and includes a polyolefin resin base material. Excellent adhesion to various substrates and high stretchability exceeding 200%, excellent conductivity at high stretch and after stretch, and repeated stretch in freezing environment It has excellent retainability in the later conductivity. Moreover, when liquid rubber is used as a binder component, a conductive paint that does not contain a medium (no solvent) can be obtained.

Hereinafter, the present invention will be described in detail.
The acid-modified synthetic rubber in the present invention has a main component of synthetic rubber and contains an unsaturated carboxylic acid as a copolymerization component. Synthetic rubber is an artificially obtained unsaturated polymer having properties as an elastomer when solid, and preferred specific examples include isoprene rubber, butadiene rubber, ethylene propylene rubber (ethylene propylene diene rubber). Styrene butadiene rubber, acrylonitrile butadiene rubber, chloroprene rubber, isobutylene isoprene rubber, ethylene vinyl acetate copolymer, acrylate ester acrylonitrile copolymer, acrylate ester 2-chloroethyl vinyl ether copolymer, chlorosulfonated polyethylene rubber, polyalkylene sulfide rubber , Silicone rubber, epichlorohydrin rubber, poly (chloro-trifluoroethylene) rubber, Alphine rubber, thermoplastic elastomer (styrene, isoprene), etc. And the like. These may be used alone or in combination. Among these, isoprene rubber, butadiene rubber, and ethylene propylene rubber are preferable, and isoprene rubber is more preferable from the viewpoints of easy acid modification, adhesion to a base material, and stretchability.

  The isoprene rubber and butadiene rubber may each be a polymer having a main chain mainly composed of isoprene or butadiene as a monomer component, and even if it is a homopolymer, other unsaturated compounds, preferably monoolefin unsaturated compounds are used. It may be a copolymer obtained by polymerization. Alternatively, a part of the hydrogen may be converted to a saturated bond. The proportion of monomer units derived from aliphatic hydrocarbons (isoprene, butadiene, or hydrogenated products thereof) in the main chain is preferably 80 mol% or more. Further, in the isoprene rubber and butadiene rubber, the main chain or the terminal of the polymer may be modified with amide, hydroxy group, (meth) acryloyl group or the like, or may be epoxidized.

Furthermore, isoprene rubber and butadiene rubber may be modified, for example, a reactive group such as a (meth) acryloyl group may be introduced at the terminal, and a part of the internal olefin is hydrogenated. Also good. The copolymer may be a random copolymer, a block copolymer, or a graft copolymer, and is not particularly limited.
Specific examples of the monoolefin unsaturated compound include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, isobutene, (meth) acrylonitrile, vinyl chloride, vinylidene chloride, (meth ) Acrylamide, (meth) acrylamide vinyl acetate, (meth) acrylic acid ester, (meth) acrylic acid and the like.

  The ethylene propylene rubber is a copolymer rubber containing at least ethylene and propylene as copolymerization components. Generally, it is obtained by injecting a mixed gas of ethylene and propylene into a hydrocarbon solvent containing a Ziegler catalyst for copolymerization. Specific examples include ethylene-propylene rubber composed of ethylene and propylene, and ethylene-propylene diene rubber obtained by introducing at least one non-conjugated diene as the third component in addition to ethylene and propylene. These may be used alone or in a mixture.

  Examples of the non-conjugated diene as the third component include dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1,4-hexadiene, cyclooctadiene, and mixtures thereof.

  Characteristics such as the type and ratio of each copolymer component of the ethylene-propylene rubber and the Mooney viscosity in the present invention are not particularly limited, and known ones can be used. Further, the ethylene propylene rubber may be vulcanized or unvulcanized. Generally, vulcanized ethylene propylene rubber can be vulcanized by the following method. For example, ethylene propylene rubber can be vulcanized with a peroxide, and ethylene propylene diene rubber can be vulcanized with a peroxide or sulfur. In the case of vulcanized rubber, a vulcanization accelerator and / or a vulcanization aid may be added.

  The acid-modified synthetic rubber needs to contain an unsaturated carboxylic acid component as a copolymer component from the viewpoint of reactivity with a crosslinking agent described later and adhesion to a base material. Specific examples of the unsaturated carboxylic acid component include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, crotonic acid and the like, as well as unsaturated dicarboxylic acid half esters, Examples include half amide. Of these, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferred, and (anhydrous) maleic acid is particularly preferred from the viewpoint of ease of copolymerization with synthetic rubber. Here, (anhydrous) maleic acid means maleic acid or maleic anhydride.

  The content of the unsaturated carboxylic acid component can be quantified by measuring the acid value of the acid-modified synthetic rubber. The acid value of the acid-modified synthetic rubber is preferably in the range of 1 to 150 mgKOH / g, and the lower limit thereof is more preferably 2 mgKOH / g or more, particularly preferably 3 mgKOH / g or more, and further preferably 4 mgKOH / g or more. 5 mgKOH / g or more is most preferable. The upper limit is more preferably 130 mgKOH / g or less, particularly preferably 100 mgKOH / g or less, further preferably 80 mgKOH / g or less, and most preferably 50 mgKOH / g or less. When the acid value is less than 1 mgKOH / g, the reactivity with the cross-linking agent and the adhesion to the substrate tend to decrease. If it exceeds 150 mgKOH / g, the adhesion to the substrate and the stretchability tend to deteriorate. The acid value (mgKOH / g) of the acid-modified synthetic rubber can be measured and determined according to JISK5407.

  The unsaturated carboxylic acid component only needs to be copolymerized with the monomer component of the synthetic rubber, and the form thereof is not limited. Examples of the copolymerization state include random copolymerization, block copolymerization, and graft copolymerization (grafting). Modification).

  Specific preferred examples of the acid-modified synthetic rubber in the present invention include acid-modified isoprene rubber, acid-modified butadiene rubber, acid-modified ethylene propylene rubber (including acid-modified ethylene propylene diene rubber), acid-modified styrene butadiene rubber, and acid-modified acrylonitrile. Butadiene rubber, acid-modified chloroprene rubber, acid-modified isobutylene isoprene rubber, acid-modified ethylene vinyl acetate copolymer, acid-modified acrylic ester acrylonitrile copolymer, acid-modified acrylic ester 2-chloroethyl vinyl ether copolymer, acid-modified chlorosulfonated polyethylene rubber, acid Modified polyalkylene / sulfide rubber, acid-modified silicone rubber, acid-modified epichlorohydrin rubber, acid-modified poly (chloro-trifluoroethylene) rubber, acid-modified alphin rubber, acid-modified thermoplastic Elastomer (styrene, isoprene-based) and the like. These may be used alone or in combination. Among these, acid-modified isoprene rubber, acid-modified butadiene rubber, and acid-modified ethylene propylene rubber are preferable, and acid-modified isoprene rubber is more preferable from the viewpoint of adhesion to a substrate and stretchability.

  The number average molecular weight of the acid-modified synthetic rubber is preferably 1000 to 100,000, more preferably 2000 to 70000, particularly preferably 3000 to 50000, further preferably 4000 to 50000, and most preferably 5000 to 50000. If the number average molecular weight is less than 1000, the cohesive force of the resulting film tends to be reduced and become brittle. On the other hand, when the number average molecular weight exceeds 100,000, it becomes difficult to dissolve or disperse in a medium, and it tends to be difficult to process into a paint. The number average molecular weight of the acid-modified synthetic rubber can be determined from a calibration curve created with a polystyrene standard sample using GPC analysis.

  The acid-modified synthetic rubber is preferably a liquid rubber because it can be easily processed into a paint. Furthermore, by using liquid rubber, it is possible to obtain a conductive paint having good coating properties and good dispersibility of the conductive material without containing a medium. The liquid rubber means a rubber that is liquid at normal temperature even without containing a medium.

  Next, the crosslinking agent in the present invention will be described. The crosslinking agent of the present invention is a compound having two or more functional groups that react with the carboxylic acid contained in the acid-modified synthetic rubber. In the present invention, the acid-modified synthetic rubber forms a cross-linked structure with a cross-linking agent, thereby improving adhesion to the base material, low-temperature film-forming property, stretchability of the film, and repeated stretch under freezing. Is suppressed. Specific examples of suitable crosslinking agents include polyhydric hydrazide compounds, polyvalent amine compounds, polyvalent epoxy compounds, polyvalent isocyanate compounds (including block types), polyvalent oxazoline compounds, polyvalent carbodiimide compounds, and polyvalent melamine compounds. Etc. These may be used alone or in combination. Of these, from the viewpoints of film-forming properties at low temperatures, adhesion to substrates, and stretchability, polyhydric hydrazide compounds, polyhydric amine compounds, polyhydric epoxy compounds, and polyhydric isocyanate compounds are preferred, polyhydric hydrazide compounds, A polyvalent epoxy compound is more preferred, and a polyvalent hydrazide compound is particularly preferred. These crosslinking agents are preferably those having excellent solubility or dispersibility in a medium such as water or a solvent from the viewpoint of processing into a paint. The crosslinking agent may be high molecular weight or low molecular weight.

  The polyhydric hydrazide compound is not particularly limited as long as it has two or more hydrazide groups per molecule, and preferred specific examples include oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, iminodiacetic acid dihydrazide, Adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanediohydrazide, hexadecanedihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, diglycolic acid dihydrazide dihydrazide dihydrazide dihydrazide dihydrazide dihydrazide Terephthalic acid dihydrazide, 2,6-naphthoic acid dihydrazide, 4,4′-bisbenzenedihydrazide, 1,4-naphthoic acid dihydrazide, naphthalene-2 6-dicarbohydrazide, 3-hydroxy-2-naphthoic acid hydrazide, citric acid trihydrazide, 1,3-bis (hydrazinocarbonoethyl) -5-isopropylhydantoin, 7,11-octadecadien-1,18 -Dicarbohydrazide etc. are mentioned. These may be used alone or in combination. Among these, adipic acid dihydrazide, 1,3-bis (hydrazinocarbonoethyl) -5-isopropylhydantoin, and 7,11-octadeca from the viewpoints of film-forming properties at low temperatures, adhesion to substrates, and stretchability. Diene-1,18-dicarbohydrazide is preferred, and 1,3-bis (hydrazinocarbonoethyl) -5-isopropylhydantoin is more preferred. When a solvent-based medium is employed as the medium, 1,3-bis (hydrazinocarbonoethyl) -5-isopropylhydantoin is preferable from the viewpoint of solvent dissolution performance.

  The polyvalent epoxy compound is not particularly limited as long as it is a compound having two or more epoxy groups per molecule. Preferred specific examples include polyhydric hydroxyl compounds such as polyethylene glycol, glycerin and derivatives thereof, and sorbitol. Examples thereof include those in which a part of the hydroxyl group is a glycidyl group, a novolac type epoxy resin, a bisphenol type epoxy resin, a trisphenol methane type epoxy resin, an amino group-containing epoxy resin, and a copolymer type epoxy resin. These may be used alone or in combination.

  The content of the crosslinking agent in the conductive paint is preferably in the range of 0.1 to 30 parts by mass with respect to 100 parts by mass of the acid-modified synthetic rubber, and the lower limit is 0.5 parts by mass or more. More preferably, 1.0 part by mass or more is particularly preferable, and 2.0 part by mass or more is further preferable. The upper limit is more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less. When the amount is less than 0.1 parts by mass, the effect of crosslinking is not sufficient. When the amount exceeds 30 parts by mass, the effect of crosslinking is not improved, which is disadvantageous in terms of cost, and further, the adhesion with the substrate is deteriorated. Tend to.

Next, the conductive material in the present invention will be described. The conductive material of the present invention has conductivity in the film. Suitable specific examples of the conductive material include metal particles such as Ag, Cu, Sn, Pb, Ni, Li, Bi, In, Al, alloys thereof, ZnO, SnO ₂ , In ₂ O ₃ , Al ₂ O ₃ , CuI. Metal oxide particles such as TiO ₂ / SnO ₂ · Sb dope, metal fibers such as Al, Ni, and stainless steel, metal surface coated glass beads, and metal plated carbon. In addition, carbon black such as furnace black such as ketjen black and vulcan, carbon black such as acetylene black, thermal black and channel black, amorphous carbon particles, natural graphite particles, artificial graphite particles, expanded graphite particles, pitch micro beads, carbon fibers, etc. Examples thereof include carbon-based fine particles such as phase-grown carbon fiber, carbon nanotube, and carbon nanofiber. These may be used alone or in combination, considering the film-forming properties, conductivity when formed into a film, processability to paint, paint properties, film characteristics, and conductivity when the film is stretched. It doesn't matter. Of these, metal particles and metal oxide particles are preferable, metal particles are more preferable, and silver particles are particularly preferable among metal particles from the viewpoints of conductivity, processability to paint, and followability to expansion and contraction. Examples of the shape of the particles in the conductive material include a spherical shape, a needle shape, an elliptical spherical shape, a flake shape, a scale shape, and an indefinite shape, and are not particularly limited.

  The average particle diameter of the conductive material is preferably in the range of 0.01 to 500 μm from the viewpoints of film-forming properties, conductivity when formed into a film, processability to paint, and paint properties. 02 μm or more is more preferable, 0.05 μm or more is particularly preferable, 0.1 μm or more is further preferable, and 0.5 μm or more is most preferable. The upper limit is more preferably 200 μm or less, particularly preferably 100 μm or less, further preferably 10 μm or less, and most preferably 5 μm or less. When the average particle diameter is outside the above preferred range, the conductivity when the film is formed and the conductivity when the film is expanded and contracted tend to decrease. Conductive materials have different average particle sizes in consideration of film-forming properties, conductivity when made into a film, processability to paint, paint properties, film characteristics, conductivity when the film is stretched, etc. You may combine multiple things.

  The conductive material is preferably subjected to a surface treatment in order to improve the performance required for the application to be used, such as dispersibility and conductivity when used as a paint or film. The surface treatment is not particularly limited, but surface treatment with an organic acid, an organic acid salt, a surfactant, and a silane coupling agent is preferable from the viewpoint of conductivity, and an organic acid is more preferable, and a fatty acid is particularly used. Particularly preferred. These surface treatment materials may be used alone or in combination.

  Specific examples of suitable fatty acids include hexanoic acid, 2-ethylhexanoic acid, octanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, montanic acid, oleic acid, linoleic acid, and linolenic acid. 12-hydroxystearic acid, benzoic acid, gluconic acid, cinnamic acid, salicylic acid, gallic acid, pentadecanoic acid, heptadecanoic acid, arachidic acid, lignoceric acid, serotic acid, 2-pentylnonanoic acid, 2-hexyldecanoic acid, 2-heptyldodecane Monobasic acids such as acid, isostearic acid, palmitoleic acid, isooleic acid, elaidic acid, ricinoleic acid, gadrenic acid, erucic acid, ceracoleic acid; malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelain Acid, malic acid, phthalic acid, fumaric acid, etc. Motosan and the like. These may be used alone or in combination.

Silane coupling agents used for surface treatment of conductive materials include reactive groups (hydrolyzable groups) that easily form hydroxy groups by hydrolysis and chemically bond to inorganic materials in one molecule, and chemical bonds to organic materials. An organosilicon compound having both reactive groups (reactive functional groups) that are easy to form is preferable, and is represented by, for example, the general formula Q— (CH ₂ ) s —Si (OR) ₃ . Q is an organic functional group, s represents a number of 1 to 3, and R represents a methyl group or an ethyl group. Examples of the organic functional group of Q include an epoxy group, a vinyl group, a methacryl group, an amino group, and a mercapto group.

  The content of the conductive material in the conductive paint is preferably 50 to 9900 parts by mass with respect to 100 parts by mass of the acid-modified synthetic rubber, and the lower limit thereof is more preferably 100 parts by mass or more, and 200 parts by mass or more. Is particularly preferable, 500 parts by mass or more is more preferable, and 900 parts by mass or more is most preferable. The upper limit thereof is more preferably 4900 parts by mass or less, particularly preferably 3200 parts by mass or less, and further preferably 2400 parts by mass or less. When the content of the conductive material is less than 50 parts by mass, the conductivity tends to decrease, and when it exceeds 9900 parts by mass, the film forming property and film characteristics tend to deteriorate.

The conductive coating material of the present invention preferably contains a medium from the viewpoints of dispersibility and viscosity adjustment, coating properties and wettability of acid-modified synthetic rubber, cross-linking agent, conductive material and the like. The medium is a liquid that can dissolve and / or disperse components contained in the paint, such as an acid-modified synthetic rubber, a crosslinking agent, and a conductive material. However, liquid rubber of acid-modified synthetic rubber, liquid crosslinking agent (crosslinking agent that is liquid without containing medium), and liquid conductive material (conductive material that is liquid without containing medium) are included in the medium. I can't. The medium is preferably a volatile liquid from the viewpoint of film forming properties. The boiling point at room temperature is preferably 200 ° C. or lower, more preferably 150 ° C. or lower, particularly preferably 120 ° C. or lower, further preferably 100 ° C. or lower, and most preferably 80 ° C. or lower.
Examples of the medium include an aqueous medium and a solvent-based medium. These may be selected appropriately in consideration of the performance and purpose at the time of use, such as paint processability, paint properties, film-forming properties, and environmental conservation viewpoints. A solvent-based medium is preferable from the viewpoint of film properties and the like, and an aqueous medium is preferable from the viewpoint of environmental protection and hygiene.

  The aqueous medium is a medium containing water and may contain a solvent in addition to water in order to improve the properties and performance of the paint. The content of water in the medium is not particularly limited, but from the viewpoint of environmental conservation, it is preferably 5% by mass or more, more preferably 20% by mass or more, and particularly preferably 50% by mass or more with respect to 100% by mass of the medium. 80% by mass or more is more preferable, and 100% by mass is most preferable.

The solvent contained in the aqueous medium can be appropriately selected in consideration of the properties as a paint, and is not particularly limited, but a water-soluble solvent is preferable from the viewpoint of the stability of the paint. Preferable specific examples of the solvent contained in the aqueous medium include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec- Alcohols such as amyl alcohol, tert-amyl alcohol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol and cyclohexanol, ketones such as methyl ethyl ketone, methyl isobutyl ketone, ethyl butyl ketone and cyclohexanone , Ethers such as tetrahydrofuran, dioxane, ethyl acetate, acetic acid-n-propyl, isopropyl acetate, acetic acid-n-butyl, isobutyl acetate, acetic acid-sec-butyl, acetic acid-3-methoxybutyl, Esters such as methyl pionate, ethyl propionate, diethyl carbonate, dimethyl carbonate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, glycol derivatives such as ethylene glycol ethyl ether acetate, Furthermore, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 3-methoxy-3-methyl-1-butanol, methoxybutanol, acetonitrile, dimethylformamide, dimethylacetamide, diacetone alcohol, ethyl acetoacetate, 1,2-dimethylglycerol, 1,3-dimethylglycerol, trimethylglycerol, etc. are mentioned. These may be used alone or in combination.
Among them, ethanol, n-propanol, isopropanol, n-butanol, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, etc. are dispersible and volatile. From the viewpoint of

  The solvent-based medium is a medium made of a solvent other than water. However, water means that it is not actively added as a raw material of the medium, and a minute amount of water may be contained as an impurity or a product. The content of water in the solvent-based medium is preferably less than 5% by mass, more preferably less than 3% by mass, particularly preferably less than 2% by mass, further preferably less than 1% by mass, and less than 0.5% by mass. Most preferred. If it exceeds 5% by mass, it is difficult to define a solvent-based medium.

The solvent in the solvent-based medium can be appropriately selected in consideration of the properties as a coating material, and is not particularly limited, but is preferably a solvent excellent in solubility of the acid-modified synthetic rubber. Preferable specific examples of the solvent in the solvent-based medium include hydrocarbon solvents such as toluene, xylene, solvent naphtha, cyclohexane and solvesso; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; methyl alcohol, ethyl alcohol and isopropyl Alcohol solvents such as alcohol and isobutyl alcohol; ester solvents such as ethyl acetate and normal butyl acetate; acetate solvents such as cellosolve acetate and methoxyacetate; chlorine solvents such as methylene chloride and chloroform; dimethylformamide, dimethylacetamide, N Examples include amide solvents such as methyl-2-pyrrolidone and ether solvents such as tetrahydrofuran. These may be used alone or in combination.
Of these, toluene, cyclohexane, methyl ethyl ketone, cyclohexanone, methyl alcohol, ethyl alcohol, isopropyl alcohol, ethyl acetate, and the like are preferable from the viewpoint of volatility and solubility of the acid-modified synthetic rubber and the crosslinking agent.

  The content of the medium in the conductive paint is not particularly limited, but the components such as acid-modified synthetic rubber, cross-linking agent, conductive material, etc. contained in the paint, such as solubility and dispersibility, viewpoints of paint properties and film forming properties, etc. Therefore, the range of 0 to 95% by mass is preferable with respect to 100% by mass of the conductive paint, and the lower limit thereof is preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 20% by mass or more. The upper limit is preferably 90% by mass or less, more preferably 80% by mass or less, particularly preferably 70% by mass or less, further preferably 60% by mass or less, and most preferably 50% by mass or less.

  The conductive paint may contain an acid-modified synthetic rubber, a cross-linking agent, a conductive material, and a material other than the medium (sometimes referred to as “other materials”) as long as the effects of the present invention are not impaired. . Other materials include polyolefin resin, polyester resin, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, ethylene- (meth) acrylic acid copolymer, styrene-maleic acid resin, styrene- Butadiene resin, butadiene resin, acrylonitrile-butadiene resin, poly (meth) acrylonitrile resin, (meth) acrylamide resin, unmodified acid polyethylene resin, chlorinated polyethylene resin, chlorinated polypropylene resin, modified nylon resin, rosin and terpene Resin materials such as phenolic resin, epoxy resin, polyurethane resin, silicone resin, silicon carbide, boron carbide, titanium carbide, zirconium carbide, hafnium carbide, vanadium carbide, tantalum carbide, charcoal Various carbides such as niobium, tungsten carbide, chromium carbide, molybdenum carbide, calcium carbide and diamond carbon lactam; various nitrides such as boron nitride, titanium nitride and zirconium nitride; various borides such as zirconium boride; titanium oxide (titania) , Various oxides such as calcium oxide, magnesium oxide, zinc oxide, copper oxide, aluminum oxide, silica, colloidal silica; various titanate compounds such as calcium titanate, magnesium titanate, strontium titanate; sulfide such as molybdenum disulfide Products; various fluorides such as magnesium fluoride and carbon fluoride; various metal soaps such as aluminum stearate, calcium stearate, zinc stearate, magnesium stearate; other talc, bentonite, talc, calcium carbonate Inorganic materials such as bentonite, kaolin, glass fiber, mica, thixotropic agent, antifoaming agent, antiblocking agent, flame retardant, tackifier, hydrolysis inhibitor, leveling agent, plasticizer, antioxidant, An ultraviolet absorber, a flame retardant, a pigment, and a dye can be blended. These may be used alone or in combination. The content of other materials in the conductive paint may be appropriately selected in consideration of the purpose of addition within the range not impairing the effects of the present invention, but it is 50% by weight or less with respect to 100% by weight of the conductive paint. Preferably, it is more preferably 30% by mass or less, particularly preferably 20% by mass or less, further preferably 10% by mass or less, and most preferably 5% by mass or less.

Next, the manufacturing method of the electroconductive coating material of this invention is demonstrated. The method for producing the conductive paint is not particularly limited. Here, a case where a solvent-based medium is used as a medium, a case where an aqueous medium is used, and a case where no medium is contained will be described separately.
As a method for producing a conductive paint when a solvent-based medium is used as a medium, a solution in which an acid-modified synthetic rubber is dissolved in a solvent-based medium is obtained in advance, and the conductive material is then added to the acid-modified synthetic rubber solution. And a method of obtaining a uniform coating material by adding the crosslinking agent so as to have a preferable content of the present invention and stirring (kneading) and mixing.
In the case of using a powder or solid crosslinking agent, a method in which the crosslinking agent is separately dissolved and / or dispersed in a solvent-based medium in advance and then added to the acid-modified synthetic rubber solution is preferable. The conductive material may also be separately immersed in a solvent-based medium in advance or dispersed before being added to the acid-modified synthetic rubber solution.
In addition, depending on the type of cross-linking agent, when the cross-linking agent is used, if the pot life as a paint is short due to the acid-modified synthetic rubber reaction in the paint, there is a problem in storage stability. You may employ | adopt the method of mixing, ie, the method of using it by liquefying.

As a method for producing a conductive paint when an aqueous medium is used as a medium, an aqueous dispersion in which an acid-modified synthetic rubber is dispersed in an aqueous medium is obtained in advance, and then the acid-modified synthetic rubber aqueous dispersion is obtained. A method of obtaining a uniform coating material by adding a conductive material and a cross-linking agent so as to have a preferable content of the present invention, and stirring (kneading) and mixing may be mentioned. The production method of the acid-modified synthetic rubber aqueous dispersion is not particularly limited, but production by a method that does not use an emulsifier is preferable from the viewpoints of film conductivity, adhesion, and water resistance.
In addition, when using a powder or a solid crosslinking agent, the method of melt | dissolving and / or disperse | distributing a crosslinking agent separately to an aqueous medium beforehand, and throwing into an acid-modified synthetic rubber aqueous dispersion is preferable. The conductive material may be separately immersed in an aqueous medium or dispersed in advance and then charged into the acid-modified synthetic rubber aqueous dispersion.
In this case, depending on the type of the crosslinking agent, if the pot life as a coating is short due to the acid-modified synthetic rubber reaction in the coating and there is a problem in storage stability, the crosslinking agent is mixed immediately before coating. You may employ | adopt the method, ie, the method of using it by liquefying.

As a method for producing a conductive paint when no medium is contained, it is necessary to use liquid rubber as the acid-modified synthetic rubber. An example is a method in which a conductive material and a crosslinking agent are added to a liquid acid-modified synthetic rubber so as to have a preferable content of the present invention, and a uniform paint is obtained by stirring (kneading) and mixing. In this case, it is necessary to use a conductive material and a crosslinking agent that do not contain a medium. In addition, depending on the type of crosslinking agent, when the pot life as a coating is short due to the acid-modified synthetic rubber reaction in the coating, there is a problem with storage stability, the crosslinking agent is mixed immediately before coating, That is, a method of using two liquids may be adopted.
Here, not containing a medium in the present invention means that the medium is not actively added as a raw material, and a trace amount of medium components may be contained as impurities or products. The content of the medium is preferably less than 5% by mass, more preferably less than 3% by mass, particularly preferably less than 2% by mass, further preferably less than 1% by mass, and most preferably less than 0.5% by mass. If the amount exceeds 5% by mass, a medium drying step is required, which is disadvantageous in terms of productivity and cost.

  The conductive paint of the present invention has fluidity and can be applied. The viscosity of the conductive paint is not particularly limited. From the viewpoint of ease of handling of the paint and ease of application, the viscosity measured at 25 ° C. with a B-type viscometer is preferably in the range of 30 to 2,000,000 mPa · s, 50 to 1,000,000 mPa · s is more preferable, 100 to 500,000 mPa · s is more preferable, 500 to 100,000 mPa · s is particularly preferable, 1000 to 50,000 mPa · s is further preferable, and 1000 to 10, 000 mPa · s is most preferable.

Next, the manufacturing method of the electroconductive film of this invention is demonstrated. The conductive film of the present invention is a film derived from a conductive paint, and the carboxylic acid of the acid-modified synthetic rubber contained in the conductive paint reacts with the functional group of the crosslinking agent to form a crosslinked structure. A good conductive film can be obtained. The conductive film can be obtained by applying (printing) the conductive paint of the present invention on a substrate and performing a heat treatment such as drying or aging as necessary.
The conductive film can be used as a laminate laminated on the base material, or after being laminated on the base material, the conductive film may be peeled off from the base material. These may be appropriately selected according to the intended use, purpose, and conditions.

  The base material to which the conductive paint is applied is not particularly limited as long as it has necessary characteristics depending on the application to be used. When using as a laminated body laminated | stacked on the base material, it is preferable to select the base material which has a softness | flexibility and a stretching property on the characteristic of this invention. When the conductive film is peeled off from the base material, it is preferable to select a base material that is excellent in releasability. Preferable specific examples of the substrate include paper, cloth, polyethylene terephthalate, polyvinyl chloride, polyethylene, polyimide, fluororesin and the like. Examples of stretchable base materials include polyurethane base materials such as polyurethane and urethane rubber, and polyolefin base materials such as polypropylene, polyethylene, ethylene α-olefin, propylene α-olefin, ethylene propylene rubber, ethylene propylene diene rubber, and olefin elastomer. Examples include materials, polydimethylsiloxane (PDMS), nitrile rubber, butadiene rubber, SBS elastomer, SEBS elastomer, and the like. These may be subjected to a treatment for improving surface adhesion or a treatment for improving releasability. Among these, a polyolefin-based substrate is preferable from the viewpoint of the stability of the substrate.

  The application method is not particularly limited, and spray coating, dip coating, brush coating, shower coating, knife coating, gravure coating, screen printing, lithographic offset printing method, ink jet method, flexographic printing method, gravure offset printing method, stamping A known method such as a method, a dispensing method, or a squeegee printing can be employed.

  When a conductive paint containing a medium is used, it is preferable to provide a drying step for drying a part or all of the medium in the coating film after application. Further, the heating during drying promotes the reaction between the acid-modified synthetic rubber and the crosslinking agent, and the film-forming property is promoted. The drying temperature is not particularly limited as long as the medium volatilizes, but is preferably in the range of 40 to 200 ° C, more preferably 60 to 150 ° C, from the viewpoint of the volatility of the medium and the reactivity of the crosslinking agent. 80-120 degreeC is especially preferable. In addition, although the high temperature exceeding 150 degreeC is not required for drying of the electrically conductive coating of this invention, even if it dries at the temperature of 150 degreeC or more, if required according to the characteristic of a base material and the objective to be used, no problem. The drying time is not particularly limited, but is preferably in the range of 1 to 18000 seconds, more preferably 5 to 3600 seconds, and particularly preferably 10 to 600 seconds from the viewpoint of the volatility of the medium and the reactivity of the crosslinking agent.

  After coating, it is preferable to perform an aging treatment in order to improve various performances such as cohesive strength, strength, stretchability, and adhesion to the substrate. The temperature of the aging treatment is preferably in the range of 25 to 100 ° C, more preferably 30 to 80 ° C, and particularly preferably 40 to 60 ° C. The treatment time is preferably in the range of 1 to 360 hours, more preferably 3 to 240 hours, particularly preferably 10 to 168 hours, and further preferably 24 to 168 hours.

  The thickness of the conductive film may be appropriately selected in consideration of the purpose of the application to be used, but from the viewpoint of conductivity and elasticity, cost, etc., a range of 1 to 5000 μm is preferable, and the lower limit thereof is 2 μm or more is more preferable, 5 μm or more is particularly preferable, 10 μm or more is further preferable, and 20 μm or more is most preferable. The upper limit is more preferably 2000 μm or less, particularly preferably 1000 μm or less, further preferably 500 μm or less, and most preferably 300 μm or less. When the thickness is less than 1 μm, the conductivity and stretchability tend to decrease, and when it exceeds 5000 μm, it is disadvantageous in terms of cost.

  The conductive film of the present invention thus obtained is a film that does not have fluidity, and is excellent in cohesion, strength, adhesion to various substrates, stretchability, and stretchability. The stretchability in the present invention means that a film is cut or cracked when a tensile force is applied in the length direction of the film (for example, the horizontal direction in a circular film formed with a diameter of 100 mm and a thickness of 1 mm on a horizontal surface). It has the property of extending without destroying the material, and the property of returning to the original dimension when the tensile force is released. The preferred expansion / contraction rate in the conductive film of the present invention varies depending on the application and purpose of use, but for example, it is 25 ° C. in consideration of application in applications such as wearable device applications, flexible printed circuit boards, flexible displays, and molded circuit components. The expansion / contraction rate under the environment is preferably 50% or more, more preferably 80% or more, particularly preferably 90% or more, further preferably 150% or more, and most preferably 200% or more. For example, an expansion rate of 200% means that after extending 200%, the tensile force is released and the original size is almost restored.

The preferable conductivity of the conductive film in the present invention varies depending on the application and purpose of use, but for example, considering the application in applications such as wearable device applications, flexible printed circuit boards, flexible displays, molded circuit components, etc. The volume resistivity serving as an index of the above is preferably less than 1 × 10 ⁰ (Ω · cm), more preferably less than 1 × 10 ⁻¹ (Ω · cm), and 1 × 10 ⁻² (Ω · cm). Is particularly preferably less than 1 × 10 ⁻³ (Ω · cm), and most preferably less than 1 × 10 ⁻⁴ (Ω · cm). In the case of 1 × 10 ⁰ (Ω · cm) or more, usable applications are limited.

  The conductive film in the present invention has excellent stretchability, that is, a reduction in performance is suppressed even when the film is returned to its original length after being highly stretched. For example, even when the stretch rate is 200% (200% stretched and then stretched to the original length), the destruction of the conductive film such as cracks and tears is suppressed, and the conductivity after stretching is also good. It is possible to hold it. The volume resistivity after expansion / contraction is preferably in the range of the above preferred volume resistivity. The amount of change in volume resistivity after stretching is preferably 1000 times or less of the volume resistivity before stretching, more preferably 500 times or less, particularly preferably 100 times or less, further preferably 10 times or less, and more preferably 5 times or less. Is most preferred.

  The conductive film in the present invention is such that the conductivity is not easily lowered during elongation. The volume resistivity at the time of elongation is preferably in the range of the above preferred volume resistivity. Further, the amount of change in volume resistivity at the time of elongation is preferably 10,000 times or less of the volume resistivity before elongation, more preferably 1000 times or less, particularly preferably 100 times or less, further preferably 10 times or less, further preferably 5 times or less. Is most preferred.

  The conductive film in the present invention is such that the conductivity is not easily lowered by repeated expansion and contraction, and in particular, the conductivity is not affected even by repeated expansion and contraction in a sub-freezing environment where the conductivity tends to decrease more. It is difficult to decrease. The volume resistivity after repeated expansion and contraction in a sub-freezing environment is preferably in the above preferred volume resistivity range. In addition, the amount of change in volume resistivity after repeated expansion and contraction in a sub-freezing environment is preferably 1000 times or less, more preferably 500 times or less, particularly preferably 100 times or less, more preferably 10 times or less of the volume resistivity without elongation. The following is more preferable, and 5 times or less is most preferable.

  The conductive paint of the present invention and the conductive film obtained therefrom can be suitably used for applications and members that require flexibility and conductivity. Such preferable applications include wearable device applications, flexible printed circuit board (FPC) applications, flexible display applications, molded circuit component (MID) applications, and the like, and examples of members include wiring, antennas, and electrodes.

  In addition, since the conductive paint of the present invention and the conductive film obtained therefrom are excellent in adhesion to various substrates, a coating such as an adhesive for bonding between different substrates or between the same substrates. As an agent, it can be preferably used. When used as an adhesive, it has excellent performance in flexibility and adhesiveness. As the adhesive, an adhesive for dry lamination is suitable.

Hereinafter, the present invention will be described specifically by way of examples. However, the present invention is not limited by these.
Various characteristics were measured or evaluated by the following methods.

Characteristics of conductive film

(1) Adhesiveness to base material Using a polypropylene resin sheet, an ethylene propylene rubber sheet, a urethane rubber sheet, and a natural rubber sheet coated with the conductive paint obtained in each of Examples and Comparative Examples, JISK5400-8.5 ( In accordance with the cross cut test), make 100 mm 1 mm x 1 mm squares on the conductive film of each sheet, paste cellophane tape (TF-12 made by Nichiban Co., Ltd.) on it, and pull the cellophane tape. After peeling, the number of squares in which the conductive film did not peel from the substrate was examined in 100 mm. The test was carried out 5 times, and the average value was evaluated.
The adhesiveness in this evaluation is preferably 50 or more, more preferably 60 or more, particularly preferably 80 or more, further preferably 90 or more, and most preferably 100, which is not practically peeled off. If it is less than 50, durability and reliability in the intended use may be a problem.

(2) Conductivity <Volume resistivity>
Resistivity meter “Loresta GP” (manufactured by Mitsubishi Chemical Analytech Co., Ltd., Loresta GP MCP-T610 type resistivity) using ethylene propylene rubber sheet and natural rubber sheet coated with conductive paint obtained in each Example and Comparative Example The volume resistivity (Ω · cm) of the conductive film was determined using a 4-terminal 4-probe method (constant current application method). The test was carried out 5 times, and the average value was evaluated.

(3) Conductivity after expansion / contraction Tensile test using natural rubber sheet coated with conductive paint obtained in each example and comparative example (natural rubber sheet was selected because base material has good stretchability) Using a machine (Intesco Precision Universal Material Testing Machine Model 2020, manufactured by Intesco Corporation), the length of the test piece is based on the “Plastics—Test Method for Tensile Properties” defined in Japanese Industrial Standard (JIS) K7127: 1999. When pulled at a rate of 10 mm / min in a direction at 25 ° C. and pulled to a length (150 mm) so that the elongation ratio is 200% with respect to the length (50 mm) of the specimen before the tensile test, 30 Then, it was pulled back to the length of the previous test piece (50 mm) at a speed of 10 mm / min, and held for 30 seconds. Thereafter, the volume resistivity (Ω · cm) of the conductive film was determined with a resistivity meter “Loresta GP”. The test was carried out five times, and the average value was defined as the conductivity after expansion and contraction, and the amount of change from the low volume efficiency before the test was also determined. Moreover, the state of the electroconductive film after expansion / contraction was confirmed visually and evaluated by the following indices.
A: No change from before expansion / contraction B: Slight cracks on part of the surface.
Δ: Clear cracks and / or peeling from the substrate is less than 10% of the total area.
X: There exists a tear or a fracture | rupture, and / or there exists 10% or more of peeling from a base material.

(4) Conductivity during elongation Specified in Japanese Industrial Standard (JIS) K7127: 1999, using an ethylene propylene rubber sheet coated with the conductive paint obtained in each Example and Comparative Example, using a tensile tester. In addition, based on "Plastics-Test Method for Tensile Properties", the test piece was pulled in the length direction at a speed of 10 mm / min in an environment of 25 ° C, and stretched with respect to the length of the test piece (50 mm) before the tensile test. After holding at a length of 50% (75 mm), 90% (95 mm), and 200% (150 mm) for 30 seconds, the resistivity of the conductive film was measured with a resistivity meter “Loresta GP”. The rate (Ω · cm) was determined. The test was carried out five times, and the average value was defined as the conductivity during elongation, and the amount of change from the volume resistivity before the test was also determined.
In addition, when calculating | requiring volume resistivity using the resistivity meter "Loresta GP", the thickness of an electroconductive film is required and the thickness of the electroconductive film at the time of expansion | extension was computed by following formula (1).
Formula (1): Thickness (μm) = 100 / (100 + Elongation rate (%)) × 20 (Thickness before pulling)

(5) Conductivity after repeated expansion and contraction in a sub-freezing environment Using an ethylene propylene rubber sheet coated with the conductive paint obtained in each Example and Comparative Example, an elongation rate of 20% in an environment of −10 ° C. The volume resistivity (Ω · cm) of the conductive film was determined with a resistivity meter “Loresta GP”. The test was carried out three times, and the average value was defined as the conductivity after repeated expansion and contraction in a sub-freezing environment, and the amount of change from the volume resistivity before the test was also determined.

Production Example 1: Production of acid-modified polybutadiene rubber 280 g of butadiene rubber (manufactured by Evonik, POLYVEST MA120, maleic acid-modified polybutadiene rubber, liquid rubber, acid value 135 mgKOH / g, number average molecular weight 4000, hereinafter referred to as “butadiene MA120”) In a four-necked flask, while maintaining the system temperature at 140 ° C. in a nitrogen atmosphere, 40.0 g of maleic anhydride and 28.0 g of dicumyl peroxide as a radical generator were added over 2 hours, and then 3 Reacted for hours. After completion of the reaction, the resulting reaction product was dried under reduced pressure in a 100 ° C. vacuum dryer for 3 hours to obtain a liquid acid-modified polybutadiene rubber (hereinafter referred to as “butadiene P-1”). The obtained “butadiene P-1” had an acid value of 155 mg KOH / g and a number average molecular weight of 8,000.

Production Example 2: Production of aqueous dispersion of acid-modified isoprene rubber 120.0 g of Kuraray LIR-403 (maleic acid-modified isoprene rubber, liquid rubber, acid value) in a 1 liter glass container equipped with a stirrer and a heater 10 mg KOH / g, number average molecular weight 34000, hereinafter referred to as “isoprene LIR-403”), 120.0 g of isopropanol, 30 g of triethylamine and 330 g of distilled water are charged, the vessel is sealed, and the rotation speed of the stirring blade is 300 rpm. While stirring, the mixture was heated and the system temperature was kept at 120 ° C., and further stirred for 60 minutes. Thereafter, the mixture was cooled to 80 ° C. while stirring with air cooling, and then the pressure was reduced while maintaining the internal temperature of the 80 ° C. system at 120 ° C., and 360 g of isopropanol and water were distilled out of the system. Thereafter, the mixture was cooled to 25 ° C. while being stirred by air cooling, and the stirring was stopped, followed by filtration with a 300 mesh stainless steel filter to obtain a milky white uniform acid-modified isoprene rubber aqueous dispersion (on the stainless steel filter after filtration). In this case, no undispersed component was confirmed). Hereinafter, this aqueous dispersion is referred to as “E-1”. The “isoprene LIR-403” content of “E-1” was 50 mass%.

Production Example 3: Production 1 of silver particles (conductive material)
950 g of special grade silver nitrate is dissolved in 5 liters of pure water, 300 g of reagent primary magnesium hydroxide is added to the solution and stirred for 45 minutes with a stirrer, and then 220 g of reagent primary sodium hydroxide is dissolved in 2 liters of pure water. The solution was added and stirred for 45 minutes. The obtained residue was separated by filtration and then dried at 80 ° C. for 24 hours under atmospheric pressure. The obtained dried product was crushed with a mortar and roasted at 400 ° C. in the atmosphere for 1.5 hours. The obtained roasted product was suspended in 5 liters of pure water, 550 g of a special grade reagent sulfuric acid was added, and the mixture was stirred for 45 minutes to dissolve the magnesium salt. After dissolution of the magnesium salt, the filtered and separated silver particles were washed twice with 10 liters of pure water and dried at 60 ° C. for 24 hours under atmospheric pressure. By the above operation, 590 g of silver particles “Ag-1” was obtained. When "Ag-1" was observed with a scanning electron microscope, the average particle diameter of the primary particles was irregular silver particles of about 0.5 µm.

Production Example 4: Production 2 of silver particles (conductive material)
500 g of “Ag-1” obtained in Production Example 3 was placed in 5 liters of an isopropanol solution containing 5% by mass of octanoic acid, suspended by stirring at 40 ° C. for 30 minutes, filtered and filtered. The silver particles were washed twice with 17 liters of pure water and dried at 60 ° C. for 24 hours under atmospheric pressure. By the above operation, 490 g of silver particles “Ag-2” surface-treated with an organic acid were obtained. When “Ag-2” was observed with a scanning electron microscope, the average particle size of the primary particles was irregularly shaped silver particles of about 0.5 μm.

Production Example 5: Production of a mixture of silver particles and carbon nanotubes (conductive material) "Ag-2" obtained in Production Example 4 and multi-walled carbon nanotubes (SWENT MW100, manufactured by Southwest Nano Technologies, diameter 6-9 nm, 5 μm long, aspect ratio 556 to 833, hereinafter referred to as “S-CNT”) were mixed. The mixing ratio was such that the mass ratio of “Ag-2” / “S-CNT” was 98/2. In this way, a mixture of carbon nanotubes and “Ag-2” was obtained. This mixture is referred to as “Ag / CNT”.

Production Example 6: Production of a mixture (conductive material) of silver particles and carbon nanotubes 2
“S-CNT” and 0.006 mol / l 2-mercapto-N- (2-naphthyl) acetamide (THIONALIDE) ethanol solution were mixed. The mixing ratio of “S-CNT” and “THIONALIDE ethanol solution” was 1/99. This was sonicated for 30 minutes, filtered using a PTFE membrane, and washed several times with ethanol. This was dried to produce a carbon nanotube “CNT-A” having a mercapto group on the surface.
Next, “Ag-2” and “CNT-A” obtained in Production Example 4 were mixed. The mixing ratio was such that the mass ratio of “Ag-2” / “CNT-A” was 98/2. In this way, a mixture of a carbon nanotube having a mercapto group and “Ag-2” was obtained. This mixture is referred to as “Ag / CNT2”.

Example 1
“Isoprene LIR-403” is used as the acid-modified synthetic rubber, Amico VDH (polyhydric hydrazide compound, 1,3-bis (hydrazinocarbonoethyl) -5-isopropylhydantoin, as a cross-linking agent, manufactured by Ajinomoto Fine Techno Co., Ltd. 10% by weight solution (referred to as “VDH”) (VDH / methanol / methyl ethyl ketone (hereinafter referred to as MEK) = 10/15/75 (mass ratio)), and “Ag-2” as a conductive material. Using. First, 100 parts by mass of “isoprene LIR-403” and 100 parts by mass of a mixed solvent of cyclohexane and MEK (cyclohexane / MEK = 88/12) were mixed and dissolved to obtain a solvent solution of “isoprene LIR-403”. . With respect to 100 mass of “isoprene LIR-403” in the solvent solution of “isoprene LIR-403”, “Ag-2” is 1500 parts by mass, and “VDH” is 5 parts by mass. A 10% by mass solution of “Ag-2” and “VDH” was added to a solvent solution of “isoprene LIR-403”. This was mixed with a rotating and rotating stirrer to obtain a conductive paint composed of a solvent-based medium.
This conductive paint is made of a polypropylene resin sheet (manufactured by Okamoto Co., Ltd., polypropylene sheet, transparent, thickness 1 mm, hereinafter referred to as “PP sheet”), ethylene propylene rubber sheet (manufactured by Nitto Kako Co., Ltd., EPT410, black, thickness 1 mm, below) "EPT sheet"), urethane rubber sheet (manufactured by Nitto Kako Co., Ltd., NU50, light yellow, thickness 1 mm, hereinafter referred to as "PU sheet"), natural rubber sheet (manufactured by Togawa Rubber Co., Ltd., C-330, American rubber) , 1 mm thick, hereinafter referred to as “NR sheet”) by a silk screen printing machine, dried at 80 ° C. for 600 seconds, and then aged at 50 ° C. for 1 day to laminate a conductive film. A test specimen was prepared. In addition, it apply | coated so that the thickness of a conductive film might be set to 50 micrometers, respectively.

Examples 2-6
Instead of “isoprene LIR-403” as an acid-modified synthetic rubber,
In Example 2, Raikon 131MA5 (maleic acid-modified butadiene rubber, liquid rubber, acid value 29 mgKOH / g, number average molecular weight 4700, hereinafter referred to as “butadiene 131MA5”) manufactured by Clay Valley,
In Example 3, Lucant A-5320H manufactured by Mitsui Chemicals, Inc. (maleic acid-modified ethylene propylene rubber, liquid rubber, acid value 23 mgKOH / g, number average molecular weight 9300, hereinafter referred to as “EP rubber A-5320H”) was used.
In Example 4, Raikon 131MA20 (maleic acid-modified butadiene rubber, liquid rubber, acid value 114 mgKOH / g, number average molecular weight 5600, hereinafter referred to as “butadiene 131MA20”) manufactured by Clay Valley Co., Ltd. was used.
In Example 5, “butadiene MA120” (acid value 135 mgKOH / g) was used.
In Example 6, except that the maleic acid-modified butadiene rubber “butadiene P-1” (acid value 155 mgKOH / g) obtained in Production Example 1 was used, the same operation as in Example 1 was carried out. A test piece on which a conductive film was laminated was prepared.

Examples 7 and 8
The content of “VDH” with respect to 100 parts by mass of “isoprene LIR-403” which is an acid-modified synthetic rubber is 5 parts by mass, 0.1 parts by mass in Example 7, and 30 parts by mass in Example 8. Similarly, a test in which a conductive paint and a conductive film were laminated in the same manner as in Example 1 except that a 10 mass% solution of “VDH” was added to the solvent solution of “isoprene LIR-403”. A piece was made.

Examples 9, 10
Instead of a 10% by mass solution of “VDH” as a cross-linking agent, SR-6GL (polyhydric epoxy compound, polyglycerin polyglycidyl ether, liquid, epoxy equivalent of 175 g / eq, hereinafter “Example 9” was used in Example 9. SR-10GL ") was used as a 10% by mass solution (SR-6GL / methanol / MEK = 10/15/75 (mass ratio)). In Example 10, a 10% by mass solution of hexamethylene diisocyanate (HDI) was used. Except for using (HDH / MEK = 10/90 (mass ratio)), a test piece on which a conductive paint and a conductive film were laminated was prepared in the same manner as in Example 1.

Examples 11-13
The content of “Ag-2” with respect to 100 mass of “isoprene LIR-403” is changed from 1500 parts by mass to 50 parts by mass in Example 11 and 400 parts by mass in Example 12. In the same manner as in Example 1, except that “Ag-2” was added to the solvent solution of “isoprene LIR-403” so that the amount was 9900 parts by mass, the conductive paint and the conductive film were laminated. A test specimen was prepared.

Example 14
Using the aqueous dispersion “E-1” of acid-modified isoprene rubber produced in Production Example 2 and using a 10% by mass aqueous solution (VDH / water = 10/90 (mass ratio)) of “VDH” as a cross-linking agent, conducting “Ag-2” was used as the material. “Ag-2” so that “Ag-2” is 1500 parts by mass and “VDH” is 5 parts by mass with respect to 100 masses of “isoprene LIR-403” in “E-1”. And 10% by mass aqueous solution of “VDH” were added to “E-1”. This was mixed with a rotation / revolution stirrer to obtain a conductive paint composed of an aqueous medium.
Using this conductive paint, a test piece on which a conductive film was laminated was produced in the same manner as in Example 1.

Examples 15 and 16
Instead of a 10% by mass aqueous solution of “VDH” as a crosslinking agent, in Example 15, a 10% by mass aqueous solution (ADH) of ADH (multivalent hydrazide compound, adipic acid dihydrazide, hereinafter referred to as “ADH”) manufactured by Otsuka Chemical Co., Ltd. In Example 16, 10 mass of water-based epoxy resin W2801 (polyhydric epoxy compound, epoxy equivalent 190 g / eq, hereinafter referred to as “W2801”) manufactured by Mitsubishi Chemical Corporation was used. A test piece on which a conductive paint and a conductive film were laminated was prepared in the same manner as in Example 14 except that a% aqueous solution (W2801 / water = 10/90 (mass ratio)) was used.

Example 17
A test piece on which a conductive paint and a conductive film were laminated was prepared in the same manner as in Example 1 except that “Ag-1” was used instead of “Ag-2” as the conductive material.

Example 18
An aqueous dispersion “E-1” of acid-modified isoprene rubber was used, a 10 mass% aqueous solution of “VDH” (VDH / water = 10/90 (mass ratio)) was used as a crosslinking agent, and “Ag / CNT "was used. “Ag / CNT” so that “Ag / CNT” is 1500 parts by mass and “VDH” is 5 parts by mass with respect to 100 mass of “isoprene LIR-403” in “E-1”. And 10% by mass aqueous solution of “VDH” were added to “E-1”. This was kneaded with a three-roll mill to obtain a conductive paint made of an aqueous medium.
Using this conductive paint, a test piece on which a conductive film was laminated was produced in the same manner as in Example 1.

Example 19
“Isoprene LIR-403” (stock solution without medium) was used as the acid-modified synthetic rubber, and “VDH” (raw powder without medium) was used as the crosslinking agent. “Ag-2” and “VDH” are added so that “Ag-2” is 1500 parts by mass and “VDH” is 5 parts by mass with respect to 100 parts of “isoprene LIR-403”. did. This was kneaded with a three-roll mill to obtain a conductive paint containing no medium.
This conductive paint is applied to each base material of “PP sheet”, “EPT sheet”, “PU sheet”, “NR sheet” with a baker type applicator, dried at 80 ° C. for 600 seconds, and then at 50 ° C. Aged for 1 day to prepare a test piece on which a conductive film was laminated. In addition, it apply | coated so that the thickness of a conductive film might be set to 50 micrometers, respectively.

Example 20
“Isoprene LIR-403” (stock solution without medium) was used as the acid-modified synthetic rubber, and “SR-6GL” (stock solution without medium) was used as the crosslinking agent. “Ag-2” and “SR−” so that “Ag-2” is 1500 parts by mass and “SR-6GL” is 5 parts by mass with respect to 100 mass of “isoprene LIR-403”. 6GL "was added. This was kneaded with a three-roll mill to obtain a conductive paint containing no medium.
This conductive paint is applied to each base material of “PP sheet”, “EPT sheet”, “PU sheet”, “NR sheet” with a baker type applicator, dried at 80 ° C. for 600 seconds, and then at 50 ° C. Aged for 1 day to prepare a test piece on which a conductive film was laminated. In addition, it apply | coated so that the thickness of a conductive film might be set to 50 micrometers, respectively.

Comparative Example 1
Instead of “Isoprene LIR-403” which is an acid-modified synthetic rubber, Kuraray LIR-30 (Isoprene rubber, liquid rubber, acid value 0 mgKOH / g, number average molecular weight 28000, manufactured by Kuraray Co., Ltd.) which is a synthetic rubber which is not acid-modified. A test piece on which a conductive paint and a conductive film were laminated was produced in the same manner as in Example 1 except that “Isoprene LIR-30” was used hereinafter. However, the coating film on the test piece did not cure and had fluidity, and a conductive film could not be formed. Therefore, various evaluations were not performed (not possible).

Comparative Example 2
The same operation as in Example 1 was performed except that the crosslinking agent was not used. That is, “Ag-2” is added to “Isoprene LIR-403” in a solvent solution of “Isoprene LIR-403” so that “Ag-2” is 1500 parts by mass, and “Isoprene LIR-403” is “Isoprene LIR-403”. Was added to the solvent solution. This was mixed with a rotating and rotating stirrer to obtain a conductive paint composed of a solvent-based medium.
Using this conductive paint, a test piece on which a conductive film was laminated was produced in the same manner as in Example 1. However, the coating film on the test piece did not cure and had fluidity, and a conductive film could not be formed. Therefore, various evaluations were not performed (not possible).

Comparative Example 3
Instead of “isoprene LIR-403” which is an acid-modified synthetic rubber, Nipol IR2200 (isoprene rubber, solid, acid value 0 mgKOH / g, number average molecular weight 120,000, solid synthetic rubber which is not acid-modified) (Hereinafter referred to as “Isoprene IR2200”). That is, first, 100 parts by mass of “isoprene IR2200” and 100 parts by mass of a mixed solvent of cyclohexane and MEK (cyclohexane / MEK = 88/12) were mixed and dissolved to obtain a solvent solution of “isoprene IR2200”. “Ag-2” was added to the solvent solution of “isoprene IR2200” so that “Ag-2” was 1500 parts by mass with respect to 100 mass of “isoprene IR2200” in the solvent solution of “isoprene IR2200”. . This was mixed with a rotating and rotating stirrer to obtain a conductive paint composed of a solvent-based medium.
Using this conductive paint, a test piece on which a conductive film was laminated was produced in the same manner as in Example 1.

Comparative Example 4
JSR BR01 (butadiene rubber, solid, acid value 0 mgKOH / g, number average molecular weight 400000, hereinafter referred to as “butadiene BR01”) manufactured by JSR was used as a solid synthetic rubber not modified with acid, instead of “Isoprene IR2200”. Except for the above, a test piece in which a conductive paint and a conductive film were laminated was produced in the same manner as in Comparative Example 3.

Comparative Example 5
Nitrile group-containing rubber (manufactured by Nippon Zeon Co., Ltd., Nipol 1042, acrylonitrile content 33.3 mass%, acid value 0 mg KOH / g, veiled (solid), hereinafter referred to as “NBR1042”) 100 mass parts, diethylene glycol monomethyl ether acetate 100 The solvent was mixed with and dissolved in part by mass to obtain a solvent solution of “NBR1042”. It added to the solvent solution of "NBR1042" so that "Ag / CNT2" might be 480 mass parts with respect to 100 mass of "NBR1042" in this "NBR1042" solvent solution. This was mixed with a rotation / revolution stirrer to obtain a paint comprising a solvent-based medium.
This paint was applied to each base material of “PP sheet”, “EPT sheet”, “PU sheet”, “NR sheet” by a silk screen printer, dried at 150 ° C. for 1800 seconds, and a film was laminated. A piece was made. In addition, it apply | coated so that the thickness of a conductive film might be set to 50 micrometers, respectively.
In addition, deformation of the base material due to the heat of drying was confirmed during the preparation of the test pieces using the “PP sheet” and “EPT sheet”. For the evaluation, a deformed test piece was used.

Comparative Example 6
100 parts by mass of sulfur-containing rubber (manufactured by Toray Fine Chemical Co., Ltd., Thiocol LP-23, polysulfide resin, sulfur content 21.5% by mass, acid value 0 mgKOH / g, liquid rubber, hereinafter referred to as “LP-23”), diethylene glycol monomethyl 100 parts by mass of ether acetate was mixed and dissolved to obtain a solvent solution of “LP-23”. It added to the solvent solution of "LP-23" so that "Ag / CNT2" might be 340 mass parts with respect to 100 mass of "LP-23" in this "LP-23" solvent solution. This was mixed with a rotation / revolution stirrer to obtain a paint comprising a solvent-based medium.
This paint was applied to each base material of “PP sheet”, “EPT sheet”, “PU sheet”, “NR sheet” by a silk screen printer, dried at 150 ° C. for 1800 seconds, and a film was laminated. A piece was made. In addition, it apply | coated so that the thickness of a conductive film might be set to 50 micrometers, respectively.
In addition, deformation of the base material due to the heat of drying was confirmed during the preparation of the test pieces using the “PP sheet” and “EPT sheet”. For the evaluation, a deformed test piece was used.

  The conductive paints obtained in Examples 1 to 20 and Comparative Examples 1 to 6 are shown in Table 1. Moreover, various evaluation was performed using the test piece by which the conductive film was laminated | stacked using the conductive paint. The evaluation results are shown in Table 2.

  From the results of Table 2, Examples 1 to 20 show that the conductive paint containing the acid-modified synthetic rubber, the cross-linking agent, and the conductive material does not require a high temperature at the time of film formation, and various kinds such as a polyolefin resin base material. Adhesion to the substrate is excellent, and conductivity is also excellent. In addition, it has excellent conductivity after expansion and contraction, and also has excellent conductivity after repeated expansion and contraction in a sub-freezing environment, and excellent conductivity is maintained in all tests. It was.

On the other hand, in Comparative Example 1, the synthetic rubber was not acid-modified and a conductive film could not be formed on the substrate.
In Comparative Example 2, since the conductive coating material did not contain a crosslinking agent, a conductive film could not be formed on the substrate.
In Comparative Examples 3 to 5, since a solid synthetic rubber was used, a non-flowable coating film could be formed without containing a crosslinking agent, but it was not acid-modified and contained a crosslinking agent. Since it was not, it was inferior to adhesiveness, the electroconductivity after expansion / contraction, or at the time of expansion | extension, or it was not able to evaluate. In Comparative Example 5, since a high temperature of 150 ° C. was required for drying, deformation of the base material was confirmed.
In Comparative Example 6, since a rubber containing sulfur was used, a high temperature of 150 ° C. was required for drying, so that deformation of the base material was confirmed. Further, since the rubber was not acid-modified, the adhesion with the base material and the conductivity after stretching or after stretching were inferior or could not be evaluated.

In the evaluation of this example, test pieces having a sheet shape that is not suitable for wearable device applications, flexible printed circuit board (FPC) applications, flexible display applications, and molded circuit component (MID) applications are used. Considering the purpose of evaluation, a practical evaluation of this application is possible with a sheet-shaped test piece without having a shape suitable for each application.

Claims (24)

A conductive paint comprising an acid-modified synthetic rubber, a crosslinking agent, and a conductive material. The conductive paint according to claim 1, wherein the acid-modified synthetic rubber is a liquid rubber. The conductive paint according to claim 1 or 2, wherein the acid value of the acid-modified synthetic rubber is 1-150 mgKOH / g. The conductive paint according to any one of claims 1 to 3, wherein the acid-modified synthetic rubber comprises at least one of acid-modified isoprene rubber, acid-modified butadiene rubber, and acid-modified ethylene propylene rubber. The conductive paint according to any one of claims 1 to 4, wherein the conductive material is metal particles and has an average particle diameter of 0.01 to 500 µm. The conductive material according to any one of claims 1 to 5, wherein the conductive material is surface-treated with at least one selected from an organic acid, an organic acid salt, a surfactant, and a silane coupling agent. paint. The conductive paint according to claim 1, wherein the crosslinking agent is a polyhydric hydrazide compound and / or a polyhydric epoxy compound. Content of a crosslinking agent is 0.1-30 mass parts with respect to 100 mass parts of acid-modified synthetic rubbers, The electrically conductive coating material in any one of Claims 1-7 characterized by the above-mentioned. The conductive paint according to any one of claims 1 to 8, wherein the content of the conductive material is 50 to 9900 parts by mass with respect to 100 parts by mass of the acid-modified synthetic rubber. The conductive paint according to claim 1, which does not contain a medium. Furthermore, a solvent-type medium is contained, The electroconductive coating material in any one of Claims 1-9 characterized by the above-mentioned. Furthermore, an aqueous medium is contained, The electroconductive coating material in any one of Claims 1-9 characterized by the above-mentioned. The conductive paint according to any one of claims 1 to 12, wherein the film derived from the conductive paint has a stretching ratio of 50% or more in a 25 ° C environment. The conductive paint according to claim 1, which is a conductive paint for wearable devices. The conductive paint according to claim 1, which is a conductive paint for a flexible printed circuit board (FPC). The conductive paint according to claim 1, which is a conductive paint for a flexible display. The conductive paint according to claim 1, which is a conductive paint for molded circuit parts (MID). A conductive film characterized by being a film derived from the conductive paint according to claim 1. A conductive film containing a synthetic rubber having a crosslinked structure and a conductive material, wherein the synthetic rubber contains a compound having two or more functional groups that react with carboxylic acid per molecule, and an acid-modified synthetic rubber A conductive film characterized in that a crosslinked structure is formed by reaction with carboxylic acid. The conductive film according to claim 18 or 19, wherein the film has an expansion / contraction ratio of 50% or more in a 25 ° C environment. The conductive film according to any one of claims 18 to 20, wherein the conductive film is a wearable device conductive film. The conductive film according to any one of claims 18 to 20, which is a conductive film for a flexible printed circuit board (FPC). The conductive film according to any one of claims 18 to 20, which is a conductive film for a flexible display. The conductive film according to claim 18, which is a conductive film for molded circuit parts (MID).