TW201839779A - Electrically conductive paste, flexible wiring obtained using same, and garment-type electronic device having flexible wiring - Google Patents

Abstract

An object of the present invention is to provide a stretchable conductive film that achieves high durability at a low cost, and a wearable device using the stretchable conductive film for wiring. The solution to this problem is to mix and knead at least the following ingredients to obtain a conductive paste: a conductive filler composed of metal-coated particles with a non-surface-treated metal layer on the surface of non-conductive core particles, and an elastomer Composition of binder resin, organic solvent. In addition, the repeat durability is improved by adding an additive having a surface free energy of 30 mJ / m ² or less. The conductive film obtained from the conductive paste has high durability against repeated expansion and contraction, is suitable for wearable applications requiring elasticity, and is low cost.

Description

Conductive paste, stretchable wiring using the same, and clothes-type electronic device having stretchable wiring

The present invention relates to a conductive paste composed of a conductive filler and a binder resin, and more particularly to a conductive paste capable of forming a conductive film having elastic properties. In addition, the present invention relates to a conductive material used in a wearable electronic device that incorporates an electronic function or an electrical function into clothes and uses it, and also relates to a clothes type that has flexible electrical wiring and further has a natural wearing feeling. Electronic equipment.

Recently, wearable electronic devices have been developed that are expected to use electronic devices with input, output, computing, and communication functions in close proximity or even in close contact with the body. Wearable electronic devices are known, such as watches, glasses, and earphones, which have jewelry-like external shapes, and textile-integrated devices that incorporate electronic functions into clothing. An example of this textile-integrated device is disclosed in Patent Document 1.

Electronic equipment requires electrical wiring for power supply or signal transmission. Especially in textile-integrated wearable electronic devices, in order to cooperate with telescopic clothes, electrical wiring also seeks flexibility. Generally, electrical wiring composed of metal wires or metal foils does not have practical elasticity in nature. Therefore, metal wires or metal foils are arranged in a wave shape or repeatedly arranged in a horseshoe shape to make them have similar telescopicity. Functional approach. In the case of a metal thread, the wiring can be formed by treating the metal thread as an embroidery yarn and sewing it to clothes. However, it is self-evident that this method is not suitable for mass production. A method for forming a wiring by etching a metal foil is generally used as a method for manufacturing a printed circuit board. A method is known in which a metal foil is attached to a flexible resin sheet, and a corrugated wiring is formed in the same manner as a printed circuit board to produce a pseudo-stretchable wiring. This method uses twisting deformation of the corrugated wiring part to give it similar telescopic properties. However, the metal foil also deforms in the thickness direction due to twisting deformation. Therefore, if it is used as part of clothes, it will be very Discomfortable wearing is not ideal. In addition, when subjected to excessive deformation like during washing, the metal foil is permanently plastically deformed, and there is a problem in the durability of the wiring.

As a method for realizing a flexible conductor wiring, a method using a special conductive paste has been proposed. Conductive particles such as silver particles, carbon particles, nano carbon tubes, and elastomers such as urethane resin with elasticity, natural rubber, synthetic rubber, and solvents are kneaded to form a paste, and directly applied to clothing. Printing and drawing wiring or printing and drawing wiring in combination with a stretchable film substrate. A conductive composition composed of conductive particles and a stretchable binder resin can achieve a stretchable conductor on a large scale. When the conductive composition obtained from the paste is viewed microscopically, the resin adhesive part is deformed when an external force is applied, and the electrical conductivity is maintained within a range where the electrical links of the conductive particles are not interrupted. Although the specific resistance observed on Juguan is higher than that of metal wires or metal foils, because the composition itself has elasticity, it is not necessary to use shapes such as wave wiring. In terms of wiring width and thickness, ， High degree of freedom, so it can realize wiring with lower resistance than metal wires in practice.

Patent Document 2 discloses a technique of suppressing a decrease in conductivity during elongation by combining silver particles with silicone rubber and then coating the conductive film on the silicone rubber substrate with the silicone rubber. Patent Document 3 discloses that a combination of silver particles and a polyurethane emulsion can obtain a conductive film with high conductivity and high elongation. In addition, many people have proposed an example in which conductive particles with a high aspect ratio such as a carbon nanotube or a silver filler are combined to try to improve the characteristics.

Patent Document 4 discloses a technique for directly forming electrical wiring on clothing using a printing method. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2-234901 [Patent Literature 2] Japanese Patent Application Laid-Open No. 2007-173226 [Patent Literature 3] Japanese Patent Application Laid-Open No. 2012-54192 [Patent Literature 4] Japanese Patent No. 3723565

[Problems to be Solved by the Invention]

As for conductive particles, precious metals such as silver are often used, but these precious metals are expensive, and pastes and conductive films prepared using these precious metals account for almost all chemical costs. On the other hand, for the purpose of reducing the cost of fillers, attempts have been made to coat precious metals with non-conductive particles or inexpensive metal particles as fillers for conductive films. In order to prevent agglomeration in the manufacturing process, the metal-coated particles thus obtained are subjected to a high dispersion treatment using a surface treatment agent. However, if the highly dispersed treatment particles are used as a conductive filler, the aggregation of the fillers will be prevented. It is difficult to maintain the conductive network when the film is elongated, and it is necessary to increase the blending ratio of the conductive particles in the film. However, if the blending ratio of the conductive particles in the film is increased, there is a problem that the ratio of the binder component is lowered and the durability at the time of stretching is deteriorated. The inventors of the present case continue to explore the application of silver-coated particles in a conductive paste for forming a stretchable conductive film. In the case of stretchable conductive films, it is rare to discuss the silver-coated particle system. [Means for solving problems]

In order to develop a conductive paste to obtain a low-cost, highly durable, stretchable conductive film, the inventors of the present case conducted intensive research and found that by using silver-coated particles without surface treatment, and further By combining specific additives, high conductivity can be obtained when the film is stretched, and the following inventions have been completed.

That is, the present invention has the following configuration. [1] A conductive paste, which is used to form stretchable wiring, and is characterized in that it contains at least: a conductive filler composed of metal-coated particles having a metal layer on the surface of non-conductive core particles; a binder The resin is composed of an elastomer; and the organic solvent, the surface of the conductive filler has not been surface-treated in advance. [2] The conductive paste according to [1], wherein the binder resin is a nitrile group-containing elastomer or a urethane resin. [3] The conductive paste according to [1] or [2], which contains 0.1 to 3.0% by mass of an additive having a surface free energy of 30 mJ / m ² or less with respect to the conductive filler. [4] The conductive paste according to [3], wherein the additive is polydimethyl silicon having at least one terminal having one or more functional groups selected from the group consisting of an amine group, a carboxyl group, and an epoxypropyl group. Oxane. [5] The conductive paste according to [3] or [4], wherein the surface free energy of the additive is 25 mJ / m ² or less. [6] The conductive paste according to any one of [3] to [5], wherein the additive is a polydimethylsiloxane having a carboxyl group at least at one terminal. [7] A retractable conductive film characterized by containing at least: a conductive filler composed of metal-coated particles having a metal layer on the surface of a non-conductive core particle; a binder resin composed of an elastomer; and an organic Solvent, the surface of the conductive filler has not been surface-treated in advance. [8] The stretchable conductive film according to [7], wherein the adhesive resin is a nitrile group-containing elastomer or a urethane resin. [9] The stretchable conductive film according to [7] or [8], which contains 0.1 to 3.0% by mass of an additive having a surface free energy of 30 mJ / m ² or less with respect to the conductive filler. [10] The stretchable conductive film according to [9], wherein the additive is a polydimethylsiloxane having at least one terminal having one or more functional groups selected from the group consisting of an amine group, a carboxyl group, and an epoxypropyl group. Siloxane. [11] The stretchable conductive film according to [9] or [10], wherein the surface free energy of the additive is 25 mJ / m ² or less. [12] The stretchable conductive film according to any one of [9] to [11], wherein the additive is a polydimethylsiloxane having a carboxyl group at least at one terminal. [13] The stretchable conductive film according to any one of [7] to [12], wherein the specific resistance of the conductive film when 100% stretched is within 20 times of the specific resistance when not stretched. . [14] The stretchable conductive film according to any one of [7] to [12], wherein the conductive film maintains conductivity after being repeatedly stretched and contracted 20% for 1,000 times. [15] A clothing-type electronic device having electrical wiring composed of the stretchable conductive film according to any one of [7] to [14]. [16] The conductive paste according to [1], wherein the conductive filler composed of the metal-coated particles contains at least two types of conductive filler A and conductive filler B, and a ratio of a major diameter to a minor diameter of the conductive filler A That is, the aspect ratio is 1.5 or less. It is a metal-coated particle having a metal layer on the surface of a non-conductive core particle. The central particle diameter D is 0.5 μm or more and 15 μm or less. The ratio is 5 or more. It is a metal-coated particle having a metal layer on the surface of a non-conductive core particle. The average length L of the long diameter is 3 μm or more and 30 μm or less. The ratio of the conductive filler B to the total of the conductive filler is 25 to 60 mass. %. [17] The conductive paste according to [16], wherein the elastomer used as the binder resin is a non-crosslinked elastomer. [18] The conductive paste according to [16] or [17], wherein the binder resin is an elastomer containing a nitrile group. [19] The conductive paste according to [16] or [17], wherein the binder resin is a urethane resin. [20] A stretchable conductive film, which is composed of at least a conductive filler and a binder resin, and is characterized in that it contains at least two types of conductive filler A and conductive filler B as conductive fillers, and the long diameter of the foregoing conductive filler A The ratio to the short diameter, that is, the aspect ratio is 1.5 or less. It is a metal-coated particle having a metal layer on the surface of a non-conductive core particle. The center particle diameter D is 0.5 μm or more and 15 μm or less. The diameter ratio, that is, the aspect ratio is 5 or more. It is a metal-coated particle having a metal layer on the surface of a non-conductive core particle. The average length L of the long diameter is 10 μm or more and 30 μm or less. The ratio of conductive filler B to the total of conductive fillers It is 25 to 60% by mass, and the binder resin is an elastomer. [21] The elastic conductive film according to [20], wherein the adhesive resin is an elastomer containing a nitrile group. [22] The elastic conductive film according to [20], wherein the binder resin is a urethane resin. [23] The elastic conductive film according to any one of [20] to [22], wherein the specific resistance of the conductive film when 100% stretched is 10 times the specific resistance when non-stretched. Within. [24] The elastic conductive film according to any one of [20] to [23], wherein the conductive film maintains conductivity after being repeatedly stretched and contracted 20% for 1,000 times. [25] The elastic conductive film as described in any one of [20] to [24], wherein the specific resistance of the sheet after the torsional period of the aforementioned conductive film repeating the following torsion test 100 times is Within 3.0 times of initial specific resistance. [Torsion test: Sample: width 10mm, length 100mm (fixed at one end of the longitudinal direction of the sample, twisted by rotation at the other end) Torsion cycle: 10 forward rotations (3600 °) torsion, return to the original state, reverse rotation 10 Circle (-3600 °), twist and return to the initial state] [26] A stretchable electronic component having an electric component made of the stretchable conductive film as described in any one of [20] to [25] Wiring. [27] A clothing-type electronic device having electrical wiring composed of the elastic conductive film described in any one of [20] to [25].

The present invention preferably has the following constitution. [28] A conductive paste, which is used to form stretchable wiring, and is characterized by containing at least: a conductive filler composed of metal-coated particles having a metal layer on the surface of a non-conductive core particle; a binder Resin, composed of elastomer; and organic solvent, the surface of the conductive filler is not selected in advance from the unit of carbon number 3 to 28 and the number of double bonds in the molecule is 0 to 3 or polycarboxylic acid, carbon At least one or more surface treatment agents among aliphatic amines having a number of 3 or more and 24 or less and a number of double bonds in the molecule of 0 to 2 are surface-treated. [29] The conductive paste according to any one of [1] to [6], which is selected from a unit having a carbon number of 3 to 28 and a number of double bonds in the molecule of 0 to 3 or The content of at least one or more surface treating agents among polycarboxylic acids and aliphatic amines having 3 to 24 carbon atoms and 0 to 2 double bonds in the molecule is 3% by mass or less. [30] A stretchable conductive film characterized by containing at least: a conductive filler composed of metal-coated particles having a metal layer on the surface of a non-conductive core particle; a binder resin composed of an elastomer; and an organic Solvent, the surface of the conductive filler is not selected in advance from a unit or polycarboxylic acid having a carbon number of 3 to 28 and a molecular number of double bonds of 0 to 3, a carbon number of 3 to 24 and a molecule At least one or more surface treatment agents among aliphatic amines having a double bond number of 0 to 2 are surface-treated. [31] The stretchable conductive film according to any one of [7] to [14], which is selected from the group having a carbon number of 3 to 28 and a number of double bonds in the molecule of 0 to 3 The content of at least one or more surface treating agents among units or polycarboxylic acids, aliphatic amines having 3 to 24 carbon atoms and 0 to 2 double bonds in the molecule is 5% by mass or less. [32] The clothing-type electronic device according to [15], which has electrical wiring, is composed of the stretchable conductive film according to [30] or [31]. [Effect of the invention]

The conductive paste according to the present invention is characterized by using metal-coated particles and elastomers whose surface has not been subjected to surface treatment such as high dispersion treatment in advance. Here, examples of the surface treatment agent such as high dispersion treatment include a unit or polycarboxylic acid having a carbon number of 3 to 28 and a number of double bonds in the molecule of 0 to 3, and / or a carbon number. An aliphatic amine or a derivative thereof having 3 or more and 24 or less and a number of double bonds in the molecule of 0 to 2. By applying these surface treatment agents to improve the dispersibility of the metal-coated particles, when the coating film is prepared, the aggregation of the particles easily occurs. Even if the conductive particles are blended at a low blending ratio, the conductivity is easy to form. Network, so it will maintain the durability during expansion and contraction. In addition, by using an additive having a surface free energy of 30 mJ / m ² or less, aggregation of particles with each other is more likely to occur, and durability during expansion and contraction is high. In addition, since the conductive particles obtained by coating the surface portion of the particles with a metal have the advantage of lower raw material cost than the metal particles, a stretchable conductive paste can be produced at a lower cost.

According to the conductive paste of the present invention, the conductive fillers A and B are blended into the elastomer so that the total ratio of the conductive filler B to the total of the conductive filler becomes 25 to 60% by mass. By combining two types of conductive fillers having different aspect ratios, a conductive network can be easily formed, so the durability against repeated stretching can be improved. In addition, since the conductive particles obtained by coating the surface portion of the particles with a metal have the advantage of lower raw material cost than the metal particles, a stretchable conductive paste can be produced at a lower cost.

The conductive paste in the present invention is composed of a conductive filler having a metal layer on the surface of non-conductive core particles, a binder, and an organic solvent. The conductive filler of the present invention is not subjected to a high dispersion treatment using a unit or a polycarboxylic acid in advance, and is a metal-coated particle composed of a material having a specific resistance on the surface metal layer of 1 × 10 ^-2 Ω ･ cm or less, The central particle diameter of the system is preferably 0.5 μm or more and 15 μm or less, more preferably 0.5 μm or more and 3 μm or less, and more preferably 0.5 μm or more and 2 μm or less. Examples of the material having a specific resistance of 1 × 10 ^-2 Ωcm or less include silver, gold, platinum, palladium, copper, nickel, aluminum, zinc, lead, and tin.

In the present invention, when the conductive filler A and the conductive filler B are blended, as for the conductive filler A, the aforementioned conductive filler having a metal layer on the surface of the non-conductive core particles can be used. In addition, the conductive filler B is a material having a surface metal layer having a specific resistance of 1 × 10 ^-2 Ωcm or less. The ratio of the major axis to the minor axis, that is, the aspect ratio is 5 or more, preferably 4 or more, and more preferably 20 or more. Particles having an average length L of 3 μm or more and 30 μm or less are more preferable, and more preferably 30 or more.

The non-conductive particles in the present invention refer to particles having a specific resistance of 30 × 10 ¹⁴ Ω ･ cm or more.

In the present invention, the ratio of the conductive filler B to the total of the conductive filler is preferably 25 to 60% by mass. If the weight ratio is small, the effect of maintaining the conductive network during elongation caused by the high aspect ratio conductive filler is small. If the weight ratio is large, the effect of maintaining the conductive network during elongation becomes large, but the arrangement of the coated filler will cause conductivity. The strength of the sexual film becomes smaller.

In the present invention, a surface treatment agent such as a highly dispersing treatment may be exemplified by a unit or polycarboxylic acid having a carbon number of 3 to 28 and a number of double bonds in the molecule of 0 to 3, and a carbon number of 3 Fatty amines or derivatives thereof having a number of double bonds of 0 to 2 and less than 24 in the molecule. In the present invention, the high-dispersion treatment without applying a unit or a polycarboxylic acid in advance means that the surface treatment with these surface-treating agents has not been performed. In more detail, the content of these surface treatment agents with respect to the whole paste is 5000 ppm or less, preferably 2000 ppm or less, and even more preferably 1200 ppm or less. These surface treatment agents are more effective if the raw material metal filler is treated in advance, but the effects can also be obtained when the paste is mixed and kneaded, so the so-called post-addition is also included in the surface treatment category.

Examples of the unit or polycarboxylic acid having 3 to 28 carbons and 0 to 3 double bonds in the molecule include crotonic acid, acrylic acid, methacrylic acid, caprylic acid, geranium Pelargonic acid, capric acid, lauric acid, myristic acid, pentacarboxylic acid, palmitic acid, palmitoleic acid, heptadecanoic acid, stearic acid, oleic acid, isooleic acid Linoleic acid, (9,12,15) -linolenic acid, (6,9,12) -linolenic acid, dihomo-γ-linolenic acid, eleostearic acid, 10- Methyl octadecanoic acid (tuberculostearic acid), arachidic acid (icosanoic acid), 8,11-icosadienoic acid, 5,8,11-icoscatrienoic acid, arachidonic acid, docosa Acid (behenic acid), lignoceric acid, nervonic acid, elaidic acid, erucic acid, docosahexaenoic acid, two Decapentaenoic acid, stearidonic acid; terephthalic acid, isophthalic acid, phthalic acid and other aromatic dicarboxylic acids; oxalic acid, malonic acid, succinic acid, glutaric acid , Adipic acid, sebacic acid, ten Dicarboxylic acids such as dioxane dicarboxylic acid and azelaic acid; dicarboxylic acids with 12 to 28 carbon atoms such as maleic acid and dimer acid; 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexane Dicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methylhexahydrophthalic anhydride, 3-methylhexahydrophthalic anhydride, 2-methylhexahydrophthalic anhydride, dicarboxylic acid Alicyclic dicarboxylic acids such as hydrogenated bisphenol A, dicarboxylic hydrogenated bisphenol S, dimer acid, hydrogenated dimer acid, hydrogenated naphthalenedicarboxylic acid, and tricyclodecanedicarboxylic acid; hydroxycarboxylic acids such as hydroxybenzoic acid and lactic acid acid. In addition, exemplified are tricarboxylic acids such as trimellitic anhydride and pyromellitic anhydride; unsaturated dicarboxylic acids such as fumaric acid; and carboxylic acid dicarboxylic acids such as dimethylolbutanoic acid and dimethylolpropionic acid. alcohol.

Examples of the aliphatic amine having 3 to 24 carbon atoms in the present invention and 0 to 2 double bonds in the molecule include capryl amine, laurylamine, myristylamine, and ten Pentaamine, palmitylamine, palmitylamine, heptaamine, stearylamine, oleylamine, vacanylamine, linoleylamine, (9,12,15) -linoleylamine, (6,9 , 12) -linolenic amine, dihomo-γ-linolenic amine, eleostearyl amine, 10-methyl octadecylamine (tuberculostearyl amine), arachidamine (eicosamine), 8,11- Eicosadienylamine, 5,8,11-Eicosatrienylamine, Arachideneamine, behenyl amine, lignoceryl amine, 24 carbon Nervonyl amine, elaidyl amine, erucyl amine, docosahexaenylamine, eicosapentaenylamine, stearidonyl amine Wait.

In the present invention, the conductive paste may contain a surface treatment agent that is not intended for high dispersion. The amount of the surface treatment agent that is not intended for high dispersion is preferably 0.1 to 3.0% by mass, and more preferably 1.0 to 2.0% by mass relative to the conductive filler. Surface treatment agents not intended for high dispersing are antioxidants, reducing agents, adhesion promoters, and the like.

The additive in the present invention refers to a compound having a molecular structure that exhibits a low surface free energy and a functional group at least at one end. Examples of structures exhibiting low surface free energy include polydimethylsiloxane, fluorine-containing groups, and the like. Moreover, as a functional group, an amine group, a carboxyl group, an epoxy propyl group, etc. are mentioned, More preferably, it is a carboxyl group.

The additives in the present invention are preferably liquid at room temperature. Surface additive of the present invention is appropriate for the free energy of 30mJ / m ² or less, is 26mJ / m ² or less more preferably, is 24mJ / m ² or less and still more preferably, of 20mJ / m ² or less and more preferably. In addition, the blending amount of the additive is preferably 0.1 to 3.0% by mass, and more preferably 0.12 to 2.0% by mass relative to the conductive filler.

As an additive suitably used in the present invention, dimethylsiloxane having a molecular weight in the range of 300 to 8000 and one end of which is modified with a carboxyl group can be exemplified. As an additive suitably used in the present invention, a fluorinated carboxylic acid having a molecular weight in the range of 100 to 1,000 can be exemplified. As for the fluorine-based additive, a partially fluorinated fluorinated unit carboxylic acid that is not completely fluorinated is preferable.

The present invention may contain non-conductive particles having an average particle diameter of 0.3 μm to 10 μm. The non-conductive particles in the present invention are mainly metal oxide particles, and can be used: silicon oxide, titanium oxide, magnesium oxide, calcium oxide, aluminum oxide, iron oxide, metal sulfate, metal carbonate , Metal titanates, etc. Among the non-conductive particles of the present invention, barium sulfate particles are preferably used.

The stretch recovery rate of the adhesive resin used in the stretchable conductor layer of the present invention after 20% stretching is preferably 99% or more, more preferably 99.5% or more, and more preferably 99.85% or more. The stretch recovery rate of the binder resin is formed by forming the binder resin on a sheet having a thickness of 20 to 200 μm and a film thickness unevenness of less than 10%, and measuring it at an environment of 25 ± 3 ° C. If the stretch recovery rate of the binder resin does not fall within this range, it may be difficult to set the stretch recovery rate of the stretchable conductor layer to a predetermined range or more. In addition, if the stretch recovery rate of the adhesive resin does not fall within this range, the repeatable stretchability or torsional resistance of the conductive paste will be reduced.

The extension recovery rate in the present invention means that when the elastic conductive sheet is overhanged as shown in FIG. 3 and a load is applied to stretch it, and the load is removed to shrink it, the initial length is set to L ₀ Let the length be L ₁ when it is stretched by 20% or a predetermined%, and when it is L ₂ when the stretch load is removed, the definition is as follows: (Number 1) Stretch recovery rate = ((L ₁ -L ₂ ) / ( L ₁ -L ₀ )) × 100 [%] (Number 2) Residual strain rate = ((L ₂ -L ₀ ) / L ₀ ) × 100 [%] L ₀ Initial length L ₃ Stretch = L ₁ -L ₀ reply length L ₄ = L ₁ -L ₂ L ₅ residual strain = L ₂ -L ₀ although similar assay to JIS L 1096 laid nonwoven fabric and braid of the test method, but the differences are: the use of certain not The load is the recovery rate after stretching, but the recovery rate when it is stretched to a certain length. In actual use, it has nothing to do with the load and load applied to the stretchable conductor layer, and it is often the case that it is repeatedly stretched to a predetermined length. Therefore, the stretch recovery rate obtained by a certain load method cannot show practical performance . Unless specifically limited, the extension recovery rate is evaluated under the environment of 25 ° C ± 3 ° C.

As the binder resin in the present invention, a crosslinked or non-crosslinked elastomer is used. The present invention preferably uses a non-crosslinked elastomer. Non-crosslinkable elastomers can use thermoplastic elastomer resins with an elastic modulus of 3 to 600 MPa and a glass transition temperature of -60 ° C to 0 ° C. Examples include thermoplastic synthetic resins, rigid rubbers, and natural rubbers. Wait. In order to express the stretchability of the coating film (sheet), rubber, polyurethane resin, and polyester resin are preferred. Examples of the rubber include nitrile group-containing rubbers such as urethane rubber, acrylic rubber, silicone rubber, butadiene rubber, nitrile rubber, or hydrogenated nitrile rubber, isoprene rubber, vulcanized rubber, and styrene. Butadiene rubber, butyl rubber, chlorosulfonated polyethylene rubber, ethylene propylene rubber, vinylidene fluoride copolymer, etc. Among them, nitrile-based rubber, chloroprene rubber, chlorosulfonated polyethylene rubber, and styrene butadiene rubber are preferred, and nitrile-based rubber is particularly preferred.

The elastic modulus of the flexible resin should preferably be 3 to 600 MPa, more preferably 10 to 500 MPa, even more preferably 15 to 300 MPa, and even more preferably 20 to 150 MPa and more preferably 25 to 100 MPa.

In the urethane resin of the present invention, a soft segment composed of a polyether-based, polyester-based, or polycarbonate-based polyol can be reacted with a hard segment composed of a diisocyanate or the like. And get. As far as the composition of the soft segment is concerned, considering the degree of freedom in molecular design, polyester polyols are better.

Examples of the polyether polyol in the present invention include polyethylene glycol, polypropylene glycol, polyglycerol, polyglycerol, polytetramethylene glycol, polytetramethylenetriol, and synthesis. Polyalkylene glycols such as copolymers obtained by copolymerizing monomer materials such as cyclic ethers for the above compounds, derivatives derived from the introduction of side chains or branched structures into the above compounds, modified products, and their Mixture and so on. Among them, polytetramethylene glycol is preferred. The reason is because the mechanical properties are excellent.

As the polyester polyol in the present invention, an aromatic polyester polyol, an aromatic / aliphatic copolymerized polyester polyol, an aliphatic polyester polyol, and an alicyclic polyester polyol can be used. Regarding the polyester polyol in the present invention, any type of saturated type or unsaturated type may be used. Among them, aliphatic polyester polyols are preferred.

As the aliphatic polyester polyol, a commercially available product may be used. Specific examples of commercially available products include, for example, POLYLITE ODX-688, ODX-2044, and ODX-240 (manufactured by DIC Corporation); KURARAY POLYOL P-2010, P-2050, and P-1010 (Kuraray); TL2461, 2455, 2469 (Hitachi Kasei) and so on.

Examples of the polycaprolactone diol in the present invention include a polymer obtained by subjecting lactones such as γ-butyrolactone, ε-caprolactone, and δ-valerolactone to a ring-opening addition reaction. Caprolactone diol compounds and the like.

Examples of commercially available polycarbonate diol compounds that can be used in the present invention include KURARAY POLYOL C series manufactured by Kuraray, and DURANOL series manufactured by Asahi-Kasei Chemicals. For example: KURARAY POLYOL C-1015N, KURARAY POLYOL C-1065N, KURARAY POLYOL C-2015N, KURARAY POLYOL C2065N, KURARAY POLYOL C-1050, KURARAY POLYOL C-1090, KURARAY POLYOL C-2050, KURARAY POLYOL C-2090, DURANOL-T5650E, DURANOL-T5651, DURANOL-T5652, etc.

Examples of the diisocyanate compound in the present invention include: 2,4-diisocyanate toluene, 2,6-diisocyanate toluene, p-phenylene diisocyanate, 4,4'- Diphenylmethane diisocyanate, m-phenylene diisocyanate, 3,3'-dimethoxy-4,4'-diisocyanate diphenyl, 2,6-diisocyanate Naphthalate, 3,3'-Dimethyl-4,4'-diisocyanate diphenyl, 4,4'-diisocyanate diphenyl, 4,4'-diisocyanate diphenyl Aromatic diisocyanates such as methyl ether, 1,5-diisocyanatonaphthalate, and m-xylyl diisocyanate, or 1,6-diisocyanatohexyl, isophorone diisocyanate, Aliphatic, cycloaliphatic diisocyanates of 4,4'-diphenylmethane diisocyanate and hydrogenated ditolyl diisocyanate (o-, m-, p-). Among them, 4,4'-diisocyanate diphenylmethane, toluene 2,4-diisocyanate, toluene 2,6-diisocyanate, and isophorone diisocyanate are preferred. In addition, a triiso- or higher-functional polyisocyanate compound may be used in combination with the isocyanate as necessary.

In the polyurethane resin of the present invention, a diol compound or the like generally called a chain extender can be copolymerized as necessary.

Examples of the diol compound used as a chain extender include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propylene glycol, and 2-methyl- 1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-butyl-2-hexyl-1,3 -Propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2-methyl-2, 4-pentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, neopentyl glycol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol, 1,8-octanediol, 2-methyl-1,8-octanediol and Aliphatic diols such as 1,9-nonanediol. Or examples: low molecular weight triols such as trimethylolpropane or triethanolamine; diamine compounds such as diethylamine or 4,4'-diaminodiphenylmethane; or trimethylolpropane . Among them, 1,6-hexanediol is particularly preferred.

The glass transition temperature of the polyurethane resin of the present invention is preferably 0 ° C or lower, more preferably -60 ° C or higher and -10 ° C or lower, and most preferably -50 ° C or higher and -20 ° C or lower. If the glass transition temperature exceeds 0 ° C, the elongation of the prepared conductive coating film will become small, and there is a possibility that the resistance rises and deteriorates during elongation. When the temperature is lower than -60 ° C, the resulting conductive coating film may cause blocking. The reduction viscosity is 0.2 dl / g or more and 3.0 dl / g or less, preferably 0.3 dl / g or more and 2.5 dl / g or less, and more preferably 0.4 dl / g or more and 2.0 dl / g or less. If it is less than 0.2 dl / g, the conductive coating film may become brittle and the resistance increase during elongation may deteriorate. Moreover, when it exceeds 3.0 dl / g, the solution viscosity of a polyurethane resin composition will become high, and there exists a possibility that operability will become difficult.

When producing a polyurethane resin, tin (II) octoate, dibutyltin dilaurate, triethylamine, bismuth metal, or the like can also be used as a catalyst.

The nitrile group-containing rubber is not particularly limited if it is a nitrile group-containing rubber or an elastomer, and is preferably a nitrile rubber and a hydrogenated nitrile rubber. The copolymer of nitrile rubber-based butadiene and acrylonitrile, if the amount of acrylonitrile bonded is large, the affinity with the metal will increase, but the rubber elasticity that contributes to the stretchability will decrease. Therefore, in 100% by mass of the nitrile group-containing rubber (such as acrylonitrile butadiene copolymer rubber), the amount of bonded acrylonitrile is preferably 18 to 50% by mass, more preferably 30 to 50% by mass, and 40 to 50% by mass. 50% by mass is particularly good.

The glass transition temperature of the binder resin is preferably below 0 ° C, more preferably below -8 ° C, even more preferably below -16 ° C, and even more preferably below -24 ° C. When the glass transition temperature exceeds this range, the stretch-recovery characteristic becomes difficult to appear. The glass transition temperature can be obtained by a conventional method using differential scanning calorimetry (DSC).

The organic solvent used in the conductive paste of the present invention is preferably a boiling point of 100 ° C or more and less than 300 ° C, and more preferably a boiling point of 150 ° C or more and less than 290 ° C. If the boiling point of the organic solvent is too low, there is a concern that the solvent will volatilize during the paste manufacturing process or when the paste is used, and the component ratio constituting the conductive paste may be easily changed. On the other hand, if the boiling point of the organic solvent is too high, when a low-temperature drying step is required (for example, 150 ° C or lower), a large amount of the solvent may remain in the coating film, which may cause a decrease in the reliability of the coating film.

Examples of such a high boiling point solvent include cyclohexanone, toluene, isophorone, γ-butyrolactone, benzyl alcohol, SOLVESSO 100, 150, 200 manufactured by Exxon Chemical, propylene glycol monomethyl ether acetate, Terpineol, ethylene glycol monobutyl ether acetate, dipentylbenzene (boiling point: 260 ~ 280 ° C), tripentylbenzene (boiling point: 300 ~ 320 ° C), n-dodecanol (boiling point: 255 ~ 259 ℃), diethylene glycol (boiling point: 245 ° C), ethylene glycol monoethyl ether acetate (boiling point: 145 ° C), diethylene glycol monoethyl ether acetate (boiling point 217 ° C), diethylene glycol monobutylene Ether acetate (boiling point: 247 ° C), diethylene glycol dibutyl ether (boiling point: 255 ° C), diethylene glycol monoacetate (boiling point: 250 ° C), triethylene glycol diacetate (boiling point) : 300 ° C), triethylene glycol (boiling point: 276 ° C), triethylene glycol monomethyl ether (boiling point: 249 ° C), triethylene glycol monoethyl ether (boiling point: 256 ° C), triethylene glycol monobutyl ether (Boiling point: 271 ° C), tetraethylene glycol (boiling point: 327 ° C), tetraethylene glycol monobutyl ether (boiling point: 304 ° C), tripropylene glycol (boiling point: 267 ° C), tripropylene glycol monomethyl ether (boiling point: 243 ℃), 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (boiling point: 253 ° C) . As for petroleum-based hydrocarbons, AF SOLVENT No. 4 (boiling point: 240 to 265 ° C), No. 5 (boiling point: 275 to 306 ° C), and No. 6 (boiling point: 296 ~ 317 ° C), No. 7 (boiling point: 259 to 282 ° C), and No. 0 SOLVENT H (boiling point: 245 to 265 ° C), etc., or two or more of them may be contained as required. Such an organic solvent is appropriately contained so that the conductive silver paste has a viscosity suitable for printing and the like.

The total conductive filler of the conductive paste of the present invention: the blending ratio of the binder is preferably 25-50% by volume: 50-75% by volume, and more preferably 30-40% by volume: 60-70% by volume.

The blending ratio of the organic solvent in the present invention is 15 to 35% by weight relative to the elastic system, and preferably 20 to 30% by weight.

The conductive paste of the present invention can be obtained by mixing and dispersing using a disperser, a three-roll mill, a self-transition mixer, an attritor, a ball mill, and a sand mill.

In the conductive paste of the present invention, a thixotropic agent, a defoaming agent, a flame retardant, a tackifier, a hydrolysis inhibitor, a leveling agent, and a plasticizer may be blended within a range that does not impair the content of the invention. Agents, antioxidants, ultraviolet absorbers, pigments, dyes and other imparting agents.

The amount of the additive in the present invention is preferably a ratio of 0.1 to 10% by weight, and more preferably a ratio of 0.3 to 5% by weight, relative to the total amount of the conductive filler.

The conductive paste obtained in this way can be coated or printed on a substrate, and then the organic solvent is evaporated and dried to form a conductive coating film. The range of the film thickness is not particularly limited, and is preferably 1 μm to 1 mm. In the case of 1 μm or less, coating film defects such as pinholes are likely to occur, which may be a problem. If it exceeds 1 mm, the organic solvent is likely to remain inside the coating film, and the reproducibility of the coating film physical properties may be poor in some cases.

The base material to which the conductive silver paste is applied is not particularly limited, and is preferably a base material having flexibility or stretchability. Examples of the flexible substrate include paper, cloth, polyethylene terephthalate, polyvinyl chloride, polyethylene, and polyimide. Examples of the stretchable substrate include polyurethane, polydimethylsiloxane (PDMS), nitrile rubber, butadiene rubber, SBS elastomer, SEBS elastomer, and the like. These substrates are preferably capable of leaving creases and being stretchable in the plane direction. In this regard, a substrate made of rubber or an elastomer is preferred.

In the case where the coating film of the conductive silver paste is peeled off from the substrate, and only wirings, electrodes, and sheets of the coating film are formed, and then transfer printing is performed, it is preferable to select a substrate having excellent peelability. Specific examples include silicon sheets, Teflon (registered trademark) sheets, and the like, and the conductive coating film can be easily peeled off.

The step of applying the conductive silver paste to the substrate is not particularly limited, and it can be performed by, for example, a coating method, a printing method, or the like. As for the printing method, a screen printing method, a lithographic offset printing method, an inkjet method, a flexographic printing method, a gravure printing method, a gravure reverse printing method, an embossing method, a dispensing method, and a doctor blade printing ( squeegee printing) and so on. The conductive paste of the present invention can also be used in a method in which, after being processed into a sheet by a coating method, it is processed into a predetermined shape by punching, punching, laser cutting, cutting, etc., and laminated on a substrate.

The step of heating the substrate to which the conductive silver paste has been applied can be performed in the atmosphere, a vacuum environment, an inert gas environment, a reducing gas environment, and the like. The heating temperature is implemented in the range of 20 to 200 ° C, and is selected in consideration of the required electrical conductivity, heat resistance of the substrate, and the like. The organic solvent will volatilize, and the hardening reaction will proceed under heating depending on the occasion, and the conductivity, adhesion, and surface hardness of the conductive film after drying will become good. Below 20 ° C, the solvent may remain in the coating film and the conductivity may not be obtained. Although electrical conductivity is exhibited over a long period of time, the specific resistance may be significantly deteriorated in some cases. The ideal heating temperature is 70 ~ 180 ℃. Below 70 ° C, the thermal shrinkage of the coating film may become small, and the conductive network of the silver powder in the coating film may not be sufficiently formed and the specific resistance may be increased. Due to the denseness of the coating film, elongation and repeated stretchability may deteriorate. When the temperature exceeds 180 ° C, the substrate may be restricted due to heat resistance. If the substrate is treated for a long time, thermal degradation of the substrate may occur, and elongation and repeated stretchability may deteriorate.

The conductive paste of the present invention is ideal for forming a coating film having a specific resistance of less than 1.0 × 10 ^-3 (Ω ･ cm). If the specific resistance is 1.0 × 10 ^-3 (Ω ･ cm) or more, the expansion wiring and expansion used in the design of FPC, robots, smart wearable devices, health care sensors, displays, solar cells, RFID, game consoles, etc. For antennas and telescopic electrodes, restrictions such as coating film thickness, wiring length, and wiring width may occur, which may not be applicable.

In addition, the conductive paste of the present invention can form a coating film having a break elongation of more than 35% and a repeated stretchability evaluation with an elongation of 20%, without breaking even after repeated stretches of 50 or more times. If the elongation at break of the coating film is considered to be suitable for the human body or the joint of a robot, it is more preferably 60% or more, and from the viewpoint of reliability, it is more preferably 100% or more. In addition, when the repeated stretchability evaluation of the coating film is performed under the condition that the elongation rate of the coating film is 20%, it is better that the fracture does not occur after repeated expansion and contraction for more than 100 times. If the long-term reliability is not required for one-time use, it is 1,000 Repeated expansion and contraction more than twice is still better. [Example]

Hereinafter, the present invention will be described in more detail and specifically by exemplifying examples. The evaluation results and the like in the examples were measured by the following methods. In the examples, only "parts" means parts by weight.

<Surface energy> Using a mirror-finished metal plate, polyethylene terephthalate film, and fluororesin plate that has been plated with silver as a solid material, the contact angle between each solid material and the additive is calculated, and calculated based on the expanded Fowkes formula . In addition, the contact angle was measured using DM-501 of Kyowa Interface Chemistry Co., Ltd. The surface roughness of solid materials was polished by emery paper to make the average roughness of the center line of 0.10 μ to 0.20 μ, and the probe droplet was set to about 1 μL. . The measurement environment was 25 ° C.

<Method for preparing sample for measuring reduction viscosity, glass transition temperature, and mechanical properties> A polyurethane resin composition (PYLEN OT; manufactured by Toyobo Co., Ltd.) was applied using a coater with a gap of 300 μm and a width of 130 mm. 50 μm thick) (coated surface is 130 mm × 200 mm). The coated material was fixed to a thick paper, dried at 120 ° C for 30 minutes using a hot air dryer (DH42 manufactured by Yamato Scientific Co., Ltd.), and then cooled. Thereafter, it was peeled from the polypropylene film to obtain a sample for evaluation.

<Reduced Viscosity> 0.1 g of a sample prepared according to the aforementioned reduced viscosity sample preparation method was put into a 25 ml quantitative bottle. About 20 ml of a phenol / tetrachloroethane = 6/4 (weight ratio) mixed solvent was added and heated to dissolve the resin. After the solution was completely dissolved, a mixed solvent of phenol / tetrachloroethane = 6/4 (weight ratio) was added at 30 ° C. until the mark of 25 ml was added. After homogeneous mixing, a Ubbelohde viscometer was used to measure at 30 ° C.

<Glass transition temperature> 5 mg of the sample resin was placed in an aluminum sample pan and sealed, and a differential scanning calorimeter (DSC) DSC-7020 made by Seiko Instruments was used to raise the temperature to 100 ° C at a heating rate of 20 ° C / min. The measurement was performed to determine the temperature at the intersection of the extension line of the baseline below the glass transition temperature and the tangent line showing the maximum slope in the transition portion.

<Mechanical Properties> A sample having a sample size of 10 mm x 50 mm is cut out from a sample prepared according to a sample preparation method for measuring a mechanical property, and held by a sample fixing jig of a tensile tester (RTA-100 manufactured by ORIENTEC). The distance between the clamps was 10 mm, the stretching speed was 20 mm / min, and the temperature was 25 ° C and 60 RH%. The elastic modulus and elongation were measured five times according to the SS curve and averaged.

<Urethane group concentration> The urethane group concentration is calculated using the following formula. Urethane group concentration (eq / t) = (W ÷ (X ÷ Y)) ÷ Z × 10 ⁶ W: weight of isocyanate constituting polyurethane resin X: molecular weight of isocyanate Y: per 1 of isocyanate Molecular isocyanate number Z: total weight of raw materials constituting the polyurethane resin

<Production of conductive film> A conductive paste was coated on a stretchable urethane sheet having a thickness of 100 μm with a coater, and dried at 120 ° C. for 20 minutes to obtain a conductive film having a film thickness of about 80 μm. Sheet. The specific resistance and the repeatable stretchability were evaluated together with the urethane sheet and the conductive film formed on the urethane sheet.

<Evaluation of Specific Resistance> The sheet resistance and film thickness of the conductive coating film in the natural state (elongation 0%) were measured, and the specific resistance was calculated. The film thickness was measured using a thickness gauge SMD-565L (manufactured by TECLOCK), and the sheet resistance was measured using Loresta-GP MCP-T610 (manufactured by ANALYTECH), and the average value was used for four test pieces. Then, it performed similarly to a natural state (elongation 0%), and it extended by the following method, and measured the specific resistance at 100% elongation. In addition, the specific resistance at the time of elongation reads the value after 30 seconds after reaching a predetermined elongation. The specific resistance is calculated using the following formula. Specific resistance (Ω ･ cm) = Rs (Ω _{/ □} ) × t (cm) Here, Rs represents the sheet resistance measured under each condition, and t represents the film thickness measured under each condition.

<Evaluation of Repeated Stretchability> Using a repeated durability tester (manufactured by RHESCA, TIQ-100), the specific resistance in the state of returning to the original length (elongation 0%) after 1000 repeated stretches was measured. This repeat The expansion and contraction system repeats the expansion and contraction of 20% of the original length of the sample film and 20% of the original film length. The elongation speed and the speed of returning to the original length were both 10 mm / second. The value obtained by dividing the specific resistance after 1,000 repeated stretching times by the initial specific resistance was used as an index of repeated stretchability.

<Evaluation of core particle diameter and aspect ratio> The average particle diameter of the core particles, the average particle diameter and aspect ratio of the silver-coated particles were measured using a scanning electron microscope (model: S-4500) manufactured by Hitachi High-Technologies Co., Ltd. The software (product name: EMAX) was obtained by measuring 300 core particles at a magnification of 2000 times.

<Evaluation of torsional property> The specific resistance of the stretchable conductive sheet in the initial state and the specific resistance of the stretchable conductive sheet after repeating the torsion cycle of the twist test 100 times were calculated, and the change of the specific resistance was calculated using the following formula. Specific resistance change (times) = specific resistance of the stretchable conductor sheet after repeating the torsion cycle 100 times / specific resistance of the stretchable conductor sheet in the initial state [torsion test: sample: width 10mm, test length 100mm (by One end of the longitudinal direction of the sample is fixed, and the other end is rotated to apply torsion.) Twisting period: 10 times forward rotation (3600 °) torsion, return to the original state, 10 times reverse rotation (-3600 °) torsion, return To initial state]

<Resin Production Example 1> Polyurethane resin composition (A) was synthesized in a 1 L 4-necked flask, 100 parts of ODX-2044 (polyester diol made by DIC), and P-2010 (polyester made by Kuraray) 33 parts of glycol, 30% by weight of 1,6-hexanediol (produced by Ube Industries, Ltd.) as a chain extender was added to 125 parts of diethylene glycol monoethyl ether acetate, and it was set in a mantle heater Inside. A stirring rod with a stirring seal, a reflux cooler, a temperature detector, and a ball plug were set in a flask, and stirred at 50 ° C for 30 minutes to dissolve. 70 parts of DESMODUR I (made by Bayer, isocyanate) and 1 part of bismuth metal catalyst were added. After the temperature rise gradually caused by the reaction heat, the temperature was raised to 90 ° C. and the reaction was performed for 4 hours, thereby obtaining a polyurethane resin composition (A). The characteristics of the obtained resin are shown in Table 1.

<Resin Production Example 2> Polyurethane resin composition (B) was synthesized in a 1 L 4-necked flask, and 100 parts of ODX-2044 (polyester diol made by DIC) was used as a chain extender 1,6- 33 parts of hexanediol (manufactured by Ube Industries) was added to 100 parts of diethylene glycol monoethyl ether acetate and placed in a heating bag. A stirring rod with a stirring seal, a reflux cooler, a temperature detector, and a ball plug were set in a flask, and stirred at 50 ° C for 30 minutes to dissolve. 58 parts of T-100 (manufactured by Tosoh, isocyanate) and 0.1 part of dibutyltin dilaurate as a catalyst were added. After the temperature rise caused by the reaction heat was gentle, the temperature was raised to 90 ° C. and the reaction was performed for 4 hours, thereby obtaining a polyurethane resin composition (B). The characteristics of the obtained resin are shown in Table 1.

[Table 1]

<Preparation and Evaluation of Conductive Paste> First, a binder resin is dissolved in a half of a predetermined solvent amount, and metal particles, a treating agent, and a remaining amount of the solvent are added to the obtained solution and preliminarily prepared. After mixing, they were dispersed by a three-roll mill to paste them to obtain conductive pastes of Examples 1 to 8 and Comparative Examples 1 and 2 shown in Tables 2 and 3. The evaluation results of the obtained conductive paste are shown in Tables 2 and 3.

[Table 2]

[table 3]

In addition, in Tables 2 and 3, conductive filler 1: general-purpose type of silver coating powder made by Mitsubishi Materials Co., Ltd. (average particle diameter of 2 μm) conductive filler 2: general-purpose type of silver coating powder made by Mitsubishi Corporation (Average particle size 1.2 μm) Binder resin 1: JSR Co., Ltd. extremely high nitrile N215SL binder resin 2: Polyurethane resin composition A obtained in Resin Production Example 1 Binder resin 3: Resin Production Example 2 Polyurethane resin composition B obtained Additive 1: Pentafluorooctanoic acid (surface free energy: 18mJ / m ² ) manufactured by Tokyo Chemical Industry Co., Ltd. Additive 2: Reactive silicone oil sheet manufactured by Shin-Etsu Chemical Industry Co., Ltd. Terminal type (average carboxyl group modified at one end) (surface free energy: 22mJ / m ² ) Additive 3: Tokyo Chemical Industry Co., Ltd. dodecanedioic acid (surface free energy: 31mJ / m ² ) Solvent 1 : Isophorone solvent 2: diethylene glycol monoethyl ether acetate.

Example 1 in Table 2 is an example in which a conductive filler 1 and a binder resin 1 were used, and 0.1% by weight of the additive 1 was added to the conductive filler to prepare a paste. The initial specific resistance is 5.9 × 10 ^-4 (Ω ･ cm), the specific resistance at 100% elongation is 86 × 10 ^-4 (Ω ･ cm), and the specific resistance after 20% repetitive expansion and contraction is 5000 × 10 ^-4 (Ω ･ cm), the system is good.

Example 2 in Table 2 is an example in which a conductive filler 1 and a binder resin 1 were used, and 1% by weight of the additive 1 was added to the conductive filler to prepare a paste. The initial specific resistance is 5.4 × 10 ^-4 (Ω ･ cm), the specific resistance at 100% elongation is 52 × 10 ^-4 (Ω ･ cm), and the specific resistance after 20% repetitive expansion and contraction is 1300 × 10 ^-4 (Ω ･ cm), the system is very good.

Example 3 in Table 2 is an example in which a conductive filler 1 and a binder resin 1 were used, and 2% by weight of the additive 1 was added to the conductive filler to prepare a paste. The initial specific resistance is 6.4 × 10 ^-4 (Ω ･ cm), the specific resistance at 100% elongation is 83 × 10 ^-4 (Ω ･ cm), and the specific resistance after 20% repetitive expansion and contraction is 1100 × 10 ^-4 (Ω ･ cm), the system is very good.

Example 4 in Table 2 is an example in which a conductive filler 2 and a binder resin 1 were used, and 1% by weight of the additive 1 was added to the conductive filler to prepare a paste. The initial specific resistance is 3.5 × 10 ^-4 (Ω ･ cm), the specific resistance at 100% elongation is 30 × 10 ^-4 (Ω ･ cm), and the specific resistance after 20% repetitive expansion and contraction is 790 × 10 ^-4 (Ω ･ cm), the system is very good.

Example 5 in Table 2 is an example in which a conductive filler 1 and a binder resin 1 were used, and 1% by weight of an additive 2 was added to the conductive filler to prepare a paste. The initial specific resistance is 36.6 × 10 ^-4 (Ω ･ cm), the specific resistance at 100% elongation is 93 × 10 ^-4 (Ω ･ cm), and the specific resistance after 20% repetitive expansion and contraction is 1600 × 10 ^-4 (Ω ･ cm), the system is very good.

Example 6 is an example in which a paste is prepared by using a conductive filler 1 and a binder resin 1 without adding an additive. The initial specific resistance is 7.6 × 10 ^-4 (Ω ･ cm), the specific resistance at 100% elongation is 110 × 10 ^-4 (Ω ･ cm), and the specific resistance after 20% repetitive expansion and contraction is 6800 × 10 ^-4 (Ω ･ cm), the system is good.

Example 7 is an example in which a conductive filler 1 and a binder resin 2 are used, and 1% by weight of the additive 1 is added to the conductive filler to prepare a paste. The initial specific resistance is 5.1 × 10 ^-4 (Ω ･ cm), the specific resistance at 100% elongation is 39 × 10 ^-4 (Ω ･ cm), and the specific resistance after 20% repetitive expansion and contraction is 1250 × 10 ^-4 (Ω ･ cm), the system is very good.

Example 8 is an example in which a conductive filler 1 and a binder resin 3 are used, and 1% by weight of the additive 1 is added to the conductive filler to prepare a paste. The initial specific resistance is 5.2 × 10 ^-4 (Ω ･ cm), the specific resistance at 100% elongation is 54 × 10 ^-4 (Ω ･ cm), and the specific resistance after 20% repetitive expansion and contraction is 1000 × 10 ^-4 (Ω ･ cm), the system is very good.

Comparative Example 1 is an example in which a conductive filler 1 and a binder resin 1 were used, and 5.0% by weight of the additive 1 was added to the conductive filler to prepare a paste. The initial specific resistance is 7.2 × 10 ^-4 (Ω ･ cm), and the specific resistance at 100% elongation is 125 × 10 ^-4 (Ω ･ cm). After 20% repeated expansion and contraction, it cannot be turned on.

Comparative Example 2 is an example in which a conductive filler 1 and a binder resin 1 were used, and 1.0% by weight of an additive 3 was added to the conductive filler to prepare a paste. The initial specific resistance is 21 × 10 ^-4 (Ω ･ cm). When it is 100% stretched, it cannot be turned on after 20% repeated expansion and contraction 1000 times.

[Application Example 1] The conductive film obtained from the conductive paste obtained in Example 1 was used as a stretchable conductor layer, and the stretchable insulating polymer layer was an elastomer sheet provided with a hot-melt layer manufactured by Nisshinbo Co., Ltd. Material "MOBILON", the electrode surface layer is omitted, and each sheet is cut into a predetermined shape, and a laminated shirt is used to obtain a jersey provided with electrodes and wiring. The obtained sweat shirt provided with electrodes and wiring had circular electrodes with a diameter of 50 mm at the intersection of the axillary line and the seventh rib on the left and right sides, and a strip-shaped stretchable conductor from the circular electrode to the center of the chest was further formed on the inside. Electrical wiring composed of components. In addition, the wiring extending from the left and right electrodes to the center of the back of the neck is formed into a rectangle of 20 mm on each side at the center of the chest.

Then, a hook portion made of stainless steel was attached to the surface of one of the pair of electrode portions on the center side of the chest. In order to ensure electrical conduction with the inner wiring portion, a conductive yarn twisted with thin metal wires was used to connect the stretchable conductor composition layer to The stainless steel hooks are electrically connected. A heartbeat sensor WHS-2 made by UNION TOOL is connected via a stainless steel hook, and heartbeat data is received using an Apple-made smartphone that includes the application "myBeat" for the heartbeat sensor WHS-2. , And set to display on the screen. In the above manner, a sweatshirt incorporating a heartbeat measurement function was prepared.

The subjects were asked to wear the jersey and obtain ECG data while driving. The obtained ECG data has low noise and high resolution, and in terms of ECG, it has the qualities of analyzing psychological state, physical condition, fatigue, lethargy, tension, etc. from the changes of the heartbeat interval and the ECG waveform. Ten subjects were asked to wear the same jersey, and the feeling of wearing was evaluated. None of the subjects complained of discomfort or discomfort.

<Example 11> First, a conductive paste was prepared in accordance with the composition ratio shown in Table 4. The binder resin was dissolved in a half of a predetermined solvent amount, and metal particles were added to the obtained solution and pre-mixed, and then dispersed using a three-roll mill, thereby obtaining as shown in Table 4. Conductive paste D11.

[Table 4]

In addition, in Table 4, conductive filler A1: silver coating powder universal type (average particle diameter) made by Mitsubishi Materials Co., Ltd. conductive filler A2: silver coating powder universal type (average particle diameter) made by Mitsubishi Materials Co., Ltd. 1.2 μm) Conductive filler B: YCC technology powder made of Yokosawa Metal Industry Co., Ltd. powder silver-coated potassium titanate fiber YTA-1575 binder resin 11: JSR Co., Ltd. extremely high nitrile N215SL elongation recovery rate adhesion above 99.9% Agent resin 12: Polyurethane resin composition (B) Stretch recovery rate is 99.9% or more Solvent 1: Isophorone solvent 3: Ethylene glycol monoethyl ether acetate.

<Production of conductive film> The obtained conductive paste D11 was coated on a stretchable urethane sheet having a thickness of 1 mm by a coater, and dried at 120 ° C for 20 minutes to obtain a film thickness of about 80 μm. Sheet of conductive film. Hereinafter, if necessary, a test piece obtained by slitting a conductive film formed on the urethane sheet into a strip shape having a width of 10 mm together with the urethane sheet is used for evaluation. The evaluation results are shown in Table 4.

<Examples 12 to 15 and Comparative Examples 11 to 14> The following was performed in the same manner as in Example 11 in accordance with the composition ratios in Table 4 to obtain conductive pastes D12 to D19. The obtained conductive paste was evaluated in the same manner as in Example 11. The results are shown in Table 4.

[Application Example 2] A clothing-type electronic device for measuring an electrocardiogram with electrical wiring was manufactured by the transfer method shown in FIG. 4. First, a carbon paste to be an electrode surface layer is screen-printed on a release PET film having a thickness of 125 μm in a predetermined pattern, and dried and hardened. The screen paste is then printed into a predetermined pattern of the insulating paste to be the insulating cover layer and dried and hardened. The surface layer of the electrode for electrocardiogram measurement is a circle having a diameter of 30 mm. In addition, the insulating cover layer is a donut shape having an inner diameter of 30 mm and an outer diameter of 36 mm. The wiring portion extending from the electrode has a width of 14 mm. It is also useful to print with carbon paste at the end of the wiring portion. A circular electrode with a diameter of 10mm is used as a hook for mounting and sensor connection. The thickness of the carbon paste layer was 25 μm in terms of dry film thickness, and the insulating cover layer was 15 μm. Then, the conductive paste D11 to be a conductor layer is used to screen-print the electrode portion and the wiring portion, and dried and hardened under predetermined conditions. The electrode part has a circular shape with a diameter of 32 mm, and the wiring part has a width of 10 mm. The dry thickness on the insulating cover layer is adjusted to 30 μm. Then, adjust and screen-print the base layer so that the dry thickness is 20 μm using the same insulating paste as the insulating cover layer, and then dry it. Then print the base layer under the same conditions again, and adjust the drying time so that the solvent content becomes Residues of 25% by mass and surface stickiness were obtained to obtain printed electrical wiring having transferability. Then, the transferable printed electrical wiring obtained by the above steps is superimposed on a predetermined portion of a jersey made of knitted fabric that has been turned out, and pressed at room temperature to temporarily bond the printed electrical wiring to the inside of the jersey Then, the release PET film was peeled off, and the jersey was hung on a hanger, and then dried at 115 ° C for 30 minutes to obtain a jersey with electrical wiring. The wiring pattern is shown in FIG. 5, and the arrangement of the wiring pattern for the jersey is shown in FIG. 6. The obtained jersey with electrical wiring has a circular electrode with a diameter of 30 mm at the intersection of the axillary line and the seventh rib on the left and right sides, and a telescopic 10 mm width from the circular electrode to the center of the rear neck is formed on the inside. Electrical wiring made of flexible conductors. In addition, the wiring extending from the left and right electrodes to the center of the back neck has a gap of 5 mm in the center of the neck, and the two will not short-circuit.

Then, a hook portion made of stainless steel is mounted on the surface side of the center end of the rear neck portion. In order to ensure electrical conduction with the wiring portion on the inner side, the conductive conductor composition layer is twisted with a stainless steel hook using a conductive yarn twisted with a thin metal wire. The ministry is electrically connected. The heartbeat sensor WHS-2 made by UNION TOOL is connected to the stainless steel hook, and the heartbeat is received by an Apple-made smartphone that includes the application "myBeat" for the heartbeat sensor WHS-2. Data, and set to display on the screen. In the above manner, a sweatshirt incorporating a heartbeat measurement function was prepared.

Participants were asked to wear the sweatshirt, perform radio gymnastics part 1 and radio gymnastics part 2 continuously, and obtain the ECG data during this period. The obtained ECG data has low noise and high resolution, and in terms of ECG, it has the qualities of analyzing psychological state, physical condition, fatigue, drowsiness, tension, etc. from changes in the heartbeat interval and ECG waveforms. Ten subjects were asked to wear the same jersey, and the feeling of wearing was evaluated. None of the subjects complained of discomfort or discomfort. [Industrial availability]

As shown above, the conductive paste and the conductive film obtained from the conductive paste in the present invention can be produced at a low cost, and because of the elasticity, the repeatable flexibility and repeatability of the conductive film obtained from the above paste It has excellent twistability and repetitive elongation, and has less discomfort during wearing. By using the stretchable conductive film of the present invention in a wearable smart device, it can be applied to: use a sensor installed on clothes to detect information inherent in the human body, that is, living potential such as myoelectric potential, cardiac potential, Wearable devices such as body temperature, pulse, blood pressure, and other living information; or clothes that include electrical heating devices; wearable devices that include sensors to measure clothing pressure; clothing that measures body size using clothing pressure; Sock-type device for measuring the pressure on the soles of the feet; Wiring section integrating clothes, tents, bags, etc. made of flexible solar cell modules in textiles; Wiring section with low-frequency therapeutic devices with joints, thermotherapy machines, etc .; bending Degree sensing unit, etc. These wearable devices are not only for the human body, but also can be applied to pets, animals such as domestic animals, or mechanical devices with telescoping and bending parts. They can also be used to connect robotic devices such as robotic hands and robotic feet to the human body. And the electrical wiring of the system used. In addition, it can also be used as an implanted device that is buried in the body; an attachable device that is attached to the surface of the body or the surface of the mucous membrane; or an edible device that performs biometric information measurement in the digestive tube.

1‧‧‧ substrate (cloth)

3‧‧‧Stretchable conductor composition layer (stretchable conductor layer)

4‧‧‧ Stretch Cover (Insulation Cover)

5‧‧‧ Stretchable carbon layer (electrode surface layer)

7‧‧‧ Adhesive layer (insulating base layer)

10‧‧‧Temporary Support (Release Support)

L ₀ ‧‧‧ initial length

L ₁ ‧‧‧ Stretched at 20% or scheduled%

L ₂ ‧‧‧ Length without extension load

L ₃ ‧‧‧stretch

L ₄ ‧‧‧ Reply length

L ₅ ‧‧‧Residual strain

[Fig. 1] Fig. 1 is an SEM image of a silver-coated particle according to the present invention, which is an example of a conductive filler A (magnification 5 thousand times). [Fig. 2] Fig. 2 is a SEM image showing an example of the conductive filler B of the present invention. [Fig. 3] Fig. 3 is a schematic diagram for explaining a stretch recovery rate. [Fig. 4] Fig. 4 is a schematic step diagram showing a method for forming an electrode and an electric wiring using a transfer method in the present invention. [Fig. 5] Fig. 5 is an example of an electrode wiring produced using the conductive paste of the present invention. [FIG. 6] FIG. 6 is a schematic diagram showing a configuration of the electrode wiring in FIG. 5 of the present invention.

Claims (27)

A conductive paste, which is used to form stretchable wiring, is characterized by containing at least: a conductive filler, which is composed of metal-coated particles having a metal layer on the surface of non-conductive core particles; a binder resin, which is composed of An elastomer composition; and an organic solvent, the surface of the conductive filler has not been surface-treated in advance. For example, the conductive paste according to item 1 of the application, wherein the adhesive resin is a nitrile group-containing elastomer or a urethane resin. For example, the conductive paste of item 1 or 2 of the patent application range contains 0.1 to 3.0% by mass of an additive with a surface free energy of 30 mJ / m ² or less relative to the conductive filler. For example, the conductive paste of claim 3, wherein the additive is a polydimethylsiloxane having at least one terminal of one or more functional groups selected from the group consisting of an amine group, a carboxyl group, and an epoxy group. . For example, the conductive paste of the third scope of the patent application, wherein the surface free energy of the additive is 25 mJ / m ² or less. For example, the conductive paste according to item 3 of the patent application, wherein the additive is polydimethylsiloxane having a carboxyl group at least at one end. A retractable conductive film, characterized in that it contains at least: a conductive filler composed of metal-coated particles having a metal layer on the surface of a non-conductive core particle; a binder resin composed of an elastomer; and an organic solvent, the The surface of the conductive filler has not been surface-treated in advance. For example, the retractable conductive film according to item 7 of the application, wherein the adhesive resin is a nitrile group-containing elastomer or a urethane resin. For example, the retractable conductive film according to item 7 or 8 of the patent application scope, which contains 0.1 to 3.0% by mass of an additive with a surface free energy of 30 mJ / m ² or less relative to the conductive filler. For example, the retractable conductive film according to item 9 of the application, wherein the additive is polydimethyl silicon having at least one terminal having one or more functional groups selected from the group consisting of amine, carboxyl, and epoxypropyl groups. Oxane. For example, the retractable conductive film according to item 9 of the application, wherein the surface free energy of the additive is 25 mJ / m ² or less. For example, the retractable conductive film according to item 9 of the application, wherein the additive is a polydimethylsiloxane having a carboxyl group at least at one end. For example, the retractable conductive film according to item 7 or 8 of the patent application scope, wherein the specific resistance of the conductive film when it is 100% stretched is less than 20 times the specific resistance when it is not stretched. For example, a retractable conductive film in the scope of the patent application No. 7 or 8, wherein the conductive film maintains conductivity even after 20% repeated expansion and contraction 1000 times. A clothing-type electronic device having electrical wiring composed of a stretchable conductive film according to any one of claims 7 to 14. For example, the conductive paste of item 1 of the patent application range, wherein the conductive filler composed of metal-coated particles contains at least two types of conductive filler A and conductive filler B, and the ratio of the major axis to the minor axis of the conductive filler A is aspect ratio. The aspect ratio is 1.5 or less. It is a metal-coated particle having a metal layer on the surface of a non-conductive core particle. The center particle diameter D is 0.5 μm or more and 15 μm or less. The ratio of the major axis to the minor axis of the conductive filler B. That is, the aspect ratio is 5 or more. It is a metal-coated particle having a metal layer on the surface of a non-conductive core particle. The average length L of the long diameter is 3 μm or more and 30 μm or less. The ratio of the conductive filler B to the total of the conductive filler is 25 ~ 60% by mass. For example, the conductive paste according to item 16 of the application, wherein the elastomer used as the binder resin is a non-crosslinked elastomer. For example, the conductive paste of claim 16 or 17, wherein the adhesive resin is an elastomer containing a nitrile group. For example, the conductive paste of claim 16 or 17, wherein the binder resin is a urethane resin. A stretchable conductive film, comprising at least a conductive filler and a binder resin as constituent components, is characterized by containing at least two types of conductive filler A and conductive filler B as conductive fillers, and the major and minor diameters of the conductive filler A The aspect ratio is 1.5 or less. It is a metal-coated particle having a metal layer on the surface of a non-conductive core particle. The center particle diameter D is 0.5 μm or more and 15 μm or less. The ratio of the major and minor diameters of the conductive filler B. That is, the aspect ratio is 5 or more. It is a metal-coated particle having a metal layer on the surface of a non-conductive core particle. The average length L of the long diameter is 10 μm or more and 30 μm or less. The ratio of the conductive filler B to the total of the conductive filler is 25 ~ 60% by mass, the binder resin is an elastomer. For example, the elastic conductive film having the scope of application for patent No. 20, wherein the adhesive resin is an elastomer containing a nitrile group. For example, the elastic conductive film having the scope of application for patent No. 20, wherein the adhesive resin is a urethane resin. For example, the elastic conductive film according to any one of claims 20 to 22, wherein the specific resistance of the conductive film when 100% stretched is within 10 times of the specific resistance when non-stretched. For example, the elastic conductive film according to any one of claims 20 to 22, wherein the conductive film maintains conductivity even after being repeatedly stretched 20% for 1000 times. For example, the elastic conductive film of any one of claims 20 to 22 of the scope of application for a patent, wherein the specific resistance of the sheet after the twisting cycle of the conductive film repeating the following torsion test 100 times is the initial specific resistance Within 3.0 times; [Torsion test: Sample: width 10mm, length 100mm (the sample is fixed at one end in the longitudinal direction, and the other end is twisted by rotation at the other end) Torsion cycle: 10 times forward rotation (3600 °) torsion, return to the original state, 10 reverse rotations (-3600 °) to reverse and return to the initial state]. A stretchable electronic component having electrical wiring composed of a conductive film according to any one of claims 20 to 25. A clothing-type electronic device having electrical wiring composed of a conductive film according to any one of claims 20 to 25.