Biological electrode, biological sensor, and biological signal measuring system

Abstract

To provide a biological electrode excellent in measurement stability.SOLUTION: A biological electrode includes: a plate-shaped support part; a roughly conical elastic columnar part provided on one surface of the plate-like support part; a conductive resin layer formed so as to cover a tip of the elastic columnar part; and a conductive wire electrically connected to the conductive resin layer and disposed inside the elastic columnar part from the tip side to a base end side.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a bioelectrode, a biosensor, and a biosignal measuring system. [Background technology]

[0002] Various developments have been made in bioelectrodes so far. For example, the technology described in Patent Document 1 is known as this type of technology. Patent Document 1 describes a bioelectrode that includes an elastic base material (conductive protrusions) and a structure (base) formed on the surface of the base material (claim 1, figure 2). It is described that this base material is made by blending a nanocarbon material with an elastic base material (paragraph 0068). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-163688 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, as a result of investigations by the present inventors, it was found that the biological electrode described in Patent Document 1 above leaves room for improvement in terms of measurement stability. [Means for solving the problem]

[0005] In conventional bioelectrodes, the columnar elastic body that comes into contact with the surface of the living body and functions as a sensor has a conductive layer formed over its entire surface to ensure electrical continuity, or is entirely made of a conductive material, such as the base material described in Patent Document 1 above.

[0006] The inventors further investigated and found that when measuring bioelectric potential using a columnar elastic body entirely covered with a conductive material, the resistance fluctuates greatly, which may cause noise. Although the detailed mechanism is unclear, it is thought that this is because when the columnar elastic body comes into contact with the surface of the living body and the outside of the body is deformed in the contracting direction and the inside of the body is deformed in the expanding direction, the resistance value on the surface or near the surface of the elastic columnar part varies greatly between the outside and the inside.

[0007] As a result of further intensive research based on this knowledge, it was found that by achieving electrical continuity of the columnar elastic body through a conductive wire passing through its interior, it is possible to suppress fluctuations in resistance due to deformation of the columnar elastic body, and that by making the tip of the columnar elastic body approximately conical in shape, it is easier to follow the surface of the living body compared to a tip with a cylindrical shape, and large deformation upon contact with the living body is suppressed, thereby suppressing noise and, as a result, improving measurement stability, which led to the completion of the present invention.

[0008] According to the present invention, A plate-shaped support portion; A substantially conical elastic columnar portion provided on one surface of the plate-shaped support portion; a conductive resin layer formed so as to cover the tip of the elastic columnar portion; a conductive wire electrically connected to the conductive resin layer and disposed inside the elastic columnar portion from the distal end side to the proximal end side; A biomedical electrode is provided comprising:

[0009] Furthermore, according to the present invention, there is provided a biosensor including the above-mentioned bioelectrode. According to the present invention, there is also provided a biosignal measuring system including the above biosensor. Effect of the Invention

[0010] According to the present invention, there are provided a biological electrode having excellent measurement stability, and a biological sensor and a biological signal measurement system using the same. [Brief description of the drawings]

[0011] [Figure 1] 1A and 1B are schematic diagrams illustrating an example of a biological electrode according to the present embodiment, in which (a) is a perspective view and (b) is a cross-sectional view taken along the line AA of (a). [Diagram 2] FIG. 1 is a schematic diagram showing an overview of a biosensor according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] In this embodiment, the directions of front, back, left, right, top and bottom are defined as shown in the drawings. However, this is defined for the sake of convenience in order to easily explain the relative relationships of the components. Therefore, it does not limit the directions during the manufacture or use of the product embodying the present invention. In addition, in all the drawings, the same components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Also, the drawings are schematic diagrams and do not correspond to the actual dimensional ratio. In this specification, the term "approximately" means that a range taking into consideration manufacturing tolerances, variations, and the like is included, unless otherwise specified explicitly.

[0013] The biological electrode of this embodiment will be outlined. The biological electrode comprises a plate-shaped support portion, a generally conical elastic columnar portion provided on one side of the plate-shaped support portion, a conductive resin layer formed to cover the tip of the elastic columnar portion, and a conductive wire electrically connected to the conductive resin layer and arranged inside the elastic columnar portion from the tip side to the base end side.

[0014] The present inventors have obtained the following findings. To date, methods that have been considered for electrical continuity of the elastic columnar portion of a biological electrode include forming the entire surface with a conductive resin layer, and constructing the elastic columnar portion itself from a conductive material. However, it was found that when the elastic columnar part comes into contact with the surface of a living body, the resistance of the elastic columnar part made of the conductive resin layer and conductive material fluctuates due to the expansion and contraction deformation of the inside and outside of the elastic columnar part, which may cause noise.In addition, when the elastic columnar part deforms, there is a risk that the conductive resin layer may be broken in the part where the deformation is large.

[0015] In contrast, a structure that establishes electrical continuity in a conductive wire arranged inside an elastic columnar portion makes it possible to suppress fluctuations in resistance during deformation, compared to a structure that establishes electrical continuity using the above-mentioned method. Although the detailed mechanism is unclear, the following is thought to be the case. When the elastic columnar section comes into contact with the surface of a living body, the outside of the elastic columnar section is deformed in a contracting direction, while the inside of the elastic columnar section is deformed in a tensile direction. At this time, the conductive wire passing through the inside of the elastic columnar section is relatively small in deformation and strain compared to the surface or the vicinity of the surface of the elastic columnar section. Therefore, even when the elastic columnar section gradually deforms significantly from the time of contact, the fluctuation of the resistance value from the initial resistance (resistance at contact) is suppressed, and the generation of noise can be stably suppressed.

[0016] In addition, the columnar elastic portion having a substantially conical shape is more likely to conform to the surface of a living body when it comes into contact with the surface than a cylindrical structure, so that when the pressing force is the same, large deformation is suppressed, and thus the increase in the fluctuation of the contact resistance can be suppressed.

[0017] As described above, the biological electrode of this embodiment can suppress the generation of noise when in contact with a living body, thereby making it possible to improve measurement stability.

[0018] The bioelectrode of this embodiment can detect potential fluctuations from a living body, such as brain waves, heartbeats, muscle activity, and nervous system activity. The bioelectrode can further include connectors, electronic components, and the like to form a biosensor that can be connected to an external device. This biosensor can be wearable. By analyzing biopotentials, such as brain waves, detected by the biosensor, a biosignal measurement system can be constructed for various purposes.

[0019] The configuration of the biological electrode of this embodiment will be described in detail below.

[0020] FIG. 1 is a schematic diagram showing an overview of a biological electrode 100 of this embodiment, where (a) is a perspective view and (b) is a cross-sectional view taken along the line AA of (a).

[0021] The biological electrode 100 in FIG. 1 comprises a plate-shaped supporting portion 10, an elastic columnar portion (columnar portion 20), and a conductive resin layer 30. The plate-shaped supporting portion 10 is a plate-shaped supporting portion. The plate-like support 10 is made of an insulating elastic material, and may have at least one columnar section 20 on one surface 12 thereof. The columnar section 20 is made of an insulating elastic material, and at least a tip section 26 may have a substantially conical shape. The conductive resin layer 30 is made of a conductive elastic material, and may be formed so as to cover the surface of at least the tip 22 (part of the tip section 26) of the columnar section 20. The conductive wire 60 is disposed inside the columnar section 20 so as to be electrically connected to the conductive resin layer 30.

[0022] When the tip of the bioelectrode 100 comes into contact with the object to be measured, the bioelectric signal detected by the columnar section 20 can be transmitted to the external connection section 110 (connector) provided on the plate-shaped support section 10 via the conductive resin layer 30 and the conductive wire 60. Then, the bioelectric signal detected by the bioelectrode 100 is transmitted to the outside via the connector.

[0023] The shape of the plate-like support member 10 when viewed from above may be, for example, a substantially circular shape such as an ellipse or a perfect circle, or a substantially polygonal shape such as a square, a rectangle, a pentagon, a hexagon, etc. Corners of the polygon may be rounded. Here, viewing from the top means observing from the top direction when looking from the tip 22 of the columnar portion 20 towards the plate-shaped support portion 10.

[0024] One surface 12 of the plate-shaped support 10 may be configured as a flat surface, but may also have a curved surface that curves outward. Here, the one surface 12 may be configured as a surface that passes through at least three contact points where the inclined surface 28 of the columnar portion 20 and the plate-shaped support 10 come into contact. In addition, there may be no interface between the plate-shaped support 10 and the columnar portion 20, and the plate-shaped support 10 and the columnar portion 20 may be configured seamlessly.

[0025] The other surface 14 of the plate-shaped support portion 10 may have a structure that can be connected to a connector. For example, an electrode that can be electrically connected to a connector may be embedded in the other surface 14 opposite to the one surface 12 with a part of it exposed. Also, at least a part or the whole of the other surface 14 may be covered with a conductive elastic member. The conductive elastic member may be made of the same material as the conductive resin layer 30. Note that the side surface of the plate-shaped support 10 does not have to be covered with a conductive elastic member.

[0026] The plate-like support 10 may be configured as an integral member with the columnar portion 20. That is, the plate-like support 10 may be configured as an integral member with the multiple columnar portions 20 using the same resin material. For example, by molding a curable elastomer composition such as a silicone rubber-based curable composition described below, a molded body in which the plate-like support 10 and the multiple columnar portions 20 are seamlessly bonded can be obtained. This makes it possible to realize an elastic molded body with excellent flexibility and strength.

[0027] Each of the plate-shaped support portion 10 and the columnar portion 20 can be made of insulating silicone rubber (rubber molded body) that does not contain conductive filler and contains silicone rubber as one type of insulating elastic member.

[0028] The columnar portion 20 may be provided on one or more plate-shaped supports 10 . The shape of the columnar section 20 as viewed from above may be a substantially circular shape such as an ellipse or a perfect circle, or may be a substantially polygonal shape such as a square, a rectangle, a pentagon, a hexagon, etc. The shape of the columnar section 20 as viewed from above and the shape of the plate-like support section 10 as viewed from above may be the same. Among these, by making the shape substantially circular, preferably a perfect circle, the stability of measurement can be improved.

[0029] In addition, the outer edge of the base end 24 of the columnar section 20 in top view may be configured to have the same area as one surface 12 of the plate-like support section 10 in top view, or may be configured to have a smaller area. By increasing the contact area between the columnar section 20 and the plate-like support section 10, the durability of the biological electrode 100 can be improved.

[0030] The tip 26 of the columnar portion 20 may be configured, for example, in any one of a substantially hemispherical shape, an ellipsoidal shape, a conical shape, and a truncated conical shape. Among these, the substantially hemispherical shape and the ellipsoidal shape are used from the viewpoint of measurement stability.

[0031] The tip 22 of the columnar portion 20 may be rounded. This can prevent the tip 22 from getting caught on the living body when it comes into contact with the tip 22, improving the stability of the attachment. In addition, the tip 22 can be easily demolded after molding, improving the stability of the production. The radius of tip 22 is, for example, 0.25 mm to 5 mm, and more preferably 0.5 mm to 3 mm, in one cross-sectional view passing tip 22. By keeping the radius within this range, attachment stability and measurement stability can be improved.

[0032] The columnar portion 20 has an inclined surface 28 on at least a part of its periphery when viewed from above. The inclination angle θ of the inclined surface 28 means the angle between the side surface (inclined surface 28) of the base end 24 of the columnar portion 20 and one surface 12 in a cross-sectional view passing through the tip 22 of the columnar portion 20, as shown in Figure 1 (b). The inclination angle θ of the inclined surface 28 is, for example, 10 to 89 degrees, preferably 15 to 85 degrees, more preferably 20 to 75 degrees, and further preferably 30 to 65 degrees. By setting it to be equal to or greater than the above lower limit, it is possible to improve the conformability to the measurement surface. By setting it to be equal to or less than the above upper limit, it is possible to suppress variation in the deformation state.

[0033] The inclination angle of inclined surface 29 of tip portion 26 (the angle between inclined surface 29 and surface 12) may be the same as inclination angle θ of inclined surface 28 of base end portion 24, or may be configured to be slightly smaller than inclination angle θ. This makes it possible to appropriately adjust inclination angle θ and the angle of the radius. A corner or a radius may be formed between inclined surface 29 of tip portion 26 and inclined surface 28 of base end portion 24, or they may be configured seamlessly.

[0034] The central axis of the columnar section 20 may coincide with the center of the plate-shaped support section 10 in a cross section passing through the tip 22, or may have an eccentric structure. The central axis of the columnar section 20 having an eccentric structure may be configured to incline from the center of the plate-shaped support section 10 toward the side surface.

[0035] When the height of the plate-like support portion 10 is H1 and the height of the columnar portion 20 is H2, H2 / H1 is, for example, 0.5 to 20, preferably 1 to 15, and more preferably 2 to 10. By keeping it within such a range, it is possible to improve measurement stability and production stability.

[0036] The columnar portion 20 has a conductive wire 60 therein. The conductive wire 60 is electrically connected to the conductive resin layer 30 covering the tip 22 , and is disposed inside the columnar portion 20 from the tip portion 26 toward the base portion 24 .

[0037] The conductive wire 60 may be any known material, and may be made of, for example, conductive fiber. The conductive fibers may be one or more selected from the group consisting of metal fibers, metal-coated fibers, carbon fibers, conductive polymer fibers, conductive polymer-coated fibers, and conductive paste-coated fibers. These may be used alone or in combination of two or more.

[0038] The metal material of the metal fiber and metal-coated fiber is not limited as long as it has electrical conductivity, and examples thereof include copper, silver, gold, nickel, tin, lead, zinc, bismuth, antimony, stainless steel, aluminum, silver / silver chloride, and alloys thereof. These may be used alone or in combination of two or more. Among these, silver can be used from the viewpoint of electrical conductivity. In addition, it is preferable that the metal material does not contain metals that put a burden on the environment, such as chromium.

[0039] The fiber materials of the above-mentioned metal-coated fiber, conductive polymer-coated fiber, and conductive paste-coated fiber are not particularly limited, and may be any of synthetic fibers, semi-synthetic fibers, and natural fibers. Among these, polyester, nylon, polyurethane, silk, cotton, etc. are preferably used. These may be used alone or in combination of two or more.

[0040] Examples of the carbon fiber include PAN-based carbon fiber and pitch-based carbon fiber.

[0041] The conductive polymer material of the above-mentioned conductive polymer fibers and conductive polymer coated fibers is, for example, a mixture of conductive polymers such as polythiophene, polypyrrole, polyaniline, polyacetylene, polyphenylenevinylene, polynaphthalene, and derivatives thereof, and binder resin, or an aqueous solution of a conductive polymer such as PEDOT-PSS ((3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid)).

[0042] The resin material contained in the conductive paste of the conductive paste-coated fiber is not particularly limited, but preferably has elasticity, and may contain, for example, one or more selected from the group consisting of silicone rubber, urethane rubber, fluororubber, nitrile rubber, acrylic rubber, styrene rubber, chloroprene rubber, and ethylene propylene rubber. These may be used alone or in combination of two or more.

[0043] The conductive filler contained in the conductive paste of the conductive paste-coated fiber is not particularly limited, and may be any known conductive material, but may include one or more selected from the group consisting of metal particles, metal fibers, metal-coated fibers, carbon black, acetylene black, graphite, carbon fibers, carbon nanotubes, conductive polymers, conductive polymer-coated fibers, and metal nanowires.

[0044] The metal constituting the conductive filler is not particularly limited, but may include, for example, at least one of copper, silver, gold, nickel, tin, lead, zinc, bismuth, antimony, silver / silver chloride, or an alloy thereof, or two or more of these. Among these, silver or copper is preferred because of its high conductivity and high availability.

[0045] The conductive wire 60 may be made of a twisted yarn in which a plurality of linear conductive fibers are twisted together, thereby making it possible to prevent breakage of the conductive wire 60 during deformation.

[0046] In this specification, the coating of conductive fibers does not simply mean covering the outer surface of the fiber material, but also includes, in the case of a twisted yarn made by twisting together single fibers, impregnating the gaps between the fibers in the twisted yarn with a metal, conductive polymer, or conductive paste to coat each of the single fibers that make up the twisted yarn.

[0047] The tensile elongation at break of the conductive wire 60 is, for example, 1% to 50%, and preferably 1.5% to 45%. By setting it within such a numerical range, excessive deformation of the columnar section 20 can be suppressed while suppressing breakage during deformation. The conductive wires 60 may have various arrangements and structures as long as they provide electrical continuity inside the columnar section 20 . For example, the tip of the conductive wire 60 may have any of a structure in which it protrudes from, is substantially flush with, or is buried in the inclined surface 29 of the tip 22 or tip portion 26 of the columnar section 20. A protruding structure may be used from the viewpoint of connection stability with the conductive resin layer 30. The protruding portion of the tip of the conductive wire 60 is partially or entirely covered with the conductive resin layer 30.

[0048] The discharge structure of the tip of the conductive wire 60 may be a structure with no fold back, a structure with fold back, or a structure wound around the surface of the tip 26 of the columnar section 20. Also, the conductive wire 60 may not pass through the central axis of the columnar section 20, but may be inclined with respect to the central axis.

[0049] The other end of the conductive wire 60 opposite to the tip may have any configuration as long as it can be electrically connected to a connector connected to the other surface 14 of the plate-shaped support part 10. For example, the other end of the conductive wire 60 may pass through the base end part 24 of the columnar part 20 and further extend to one surface 12, the side surface, or the other surface 14 of the plate-shaped support part 10. The other end of the conductive wire 60 may be electrically connected to a connector via a conductive resin layer 30 provided on the other surface 14.

[0050] The conductive resin layer 30 may be configured to cover at least the surface of the tip 22 of the columnar section 20, or may be configured to cover the columnar section 20 from the tip 22 to the tip section 26, or from the tip 22 to partway to the base section 24. In other words, it is sufficient that the conductive resin layer 30 is configured not to cover the entire surface of the columnar section 20. This conductive resin layer 30 may be configured to cover one surface 12 and the other surface 14 of the plate-shaped support portion 10 , separated from the portion covering the tip 22 .

[0051] The conductive resin layer 30 is made of a conductive silicone rubber containing a conductive filler and silicone rubber as one of the conductive elastic members. For example, the conductive resin layer 30 can be formed by applying a conductive solution (conductive silicone rubber-based curable composition) in which a conductive filler is added to an insulating silicone rubber-based curable composition that does not contain a conductive filler, which will be described later, to the above-mentioned molded body. By using the same type of silicone rubber material as the silicone rubber that constitutes the plate-like support portion 10 and the columnar portion 20, the adhesion of the conductive resin layer 30 can be improved.

[0052] The conductive filler may be any known conductive material, but may include one or more selected from the group consisting of metal particles, silver / silver chloride particles, metal fibers, metal-coated fibers, carbon black, acetylene black, graphite, carbon fibers, carbon nanotubes, conductive polymers, conductive polymer-coated fibers, and metal nanowires.

[0053] The metal constituting the conductive filler is not particularly limited, but may include, for example, at least one of copper, silver, gold, nickel, tin, lead, zinc, bismuth, antimony, silver / silver chloride, or an alloy thereof, or two or more of these. Among these, silver or copper is preferred because of its high conductivity and high availability.

[0054] The lower limit of the content of the conductive filler is, for example, 30% by mass or more, preferably 35% by mass or more, and more preferably 40% by mass or more, based on 100% by mass of the silicone rubber in the conductive resin layer 30. This can improve the transmission of bioelectric signals even in the case of a thin film. On the other hand, the upper limit of the content of the conductive filler is, for example, 90% by mass or less, preferably 85% by mass or less, and more preferably 80% by mass or less, based on 100% by mass of the silicone rubber in the conductive resin layer 30. This can improve the durability of the conductive resin layer 30 against deformation of the columnar section 20.

[0055] The lower limit of the thickness of the conductive resin layer 30 is, for example, 5 μm or more, preferably 8 μm or more, and more preferably 10 μm or more. This can improve durability during repeated use. On the other hand, the upper limit of the thickness of the conductive resin layer 30 is, for example, 200 μm or less, preferably 150 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less. This can maintain the ease of deformation of the columnar section 20. In addition, by making it a thin film, it is possible to suppress the variation of the rubber hardness A of the columnar section 20 from the desired value. In a cross-sectional view of the columnar section 20, it is preferable that the thickness of at least a part of the conductive resin layer 30 on the tip 22 or side surface of the columnar section 20 is within the above numerical range.

[0056] The conductive resin layer 30 may be configured so that the thickness D1 on the surface of the tip 22 of the columnar section 20 is thicker than the thickness D2 on the surface of the other surface 14 of the plate-like support section 10. For example, after applying the conductive solution described above, a part of the columnar section 20 coated with the conductive resin layer 30 may be dipped (immersion coated) in a paste-like conductive solution. This allows the tip 22 of the columnar section 20 and a predetermined portion from the tip 22 (for example, 1 / 2, 1 / 3, or 1 / 4 of the entire columnar section 20) to be a relatively thick film. This thick film is preferably provided over the entire circumferential direction of the tip of the columnar section 20. This prevents the conductive resin layer 30 from peeling off at the tip, and prevents damage such as breakage of the columnar section 20. This improves the durability of the bioelectrode 100.

[0057] In this embodiment, the type A durometer hardness on the surface of the columnar portion 20 (elastic columnar portion) measured at 37° C. in accordance with JIS K 6253 (1997) is defined as rubber hardness A. The rubber hardness A can be measured by using the columnar portion 20, by using the plate-like support portion 10 when the columnar portion 20 and the plate-like support portion 10 are formed as an integral member, or by using the silicone rubber that constitutes them. In addition, when the conductive resin layer 30 is a thin layer and has almost no effect on the rubber hardness A, the columnar portion 20 or the plate-like support portion 10 on whose surface the conductive resin layer 30 is formed may be used as the measurement object. A test piece is made from these, and the test piece can be used as the measurement object (sample). A plurality of test pieces may be stacked to determine the sample thickness. Note that even if the distance from the indenter to the end of the test piece is less than 12 mm, it is acceptable as long as there is a certain distance.

[0058] The lower limit of the rubber hardness A is, for example, 15 or more, preferably 18 or more, and more preferably 20 or more. This reduces the contact resistance and increases the brain wave acquisition rate. On the other hand, the upper limit of the rubber hardness A is 65 or less, preferably 53 or less, and more preferably 50 or less. This reduces the contact resistance. In addition, the columnar portion 20 can easily deform when contacting the measurement part and can deform to a state following the shape of the measurement part, thereby improving the wearing comfort of the subject (user) and suppressing discomfort during use over time.

[0059] Here, the silicone rubber-based hardening composition will be described. The silicone rubber can be a cured product of a silicone rubber-based curable composition. The curing process of the silicone rubber-based curable resin composition is carried out, for example, by heating at 100 to 250°C for 1 to 30 minutes (first curing) and then post-baking at 100 to 200°C for 1 to 4 hours (second curing).

[0060] The insulating silicone rubber is a silicone rubber that does not contain a conductive filler, and the conductive silicone rubber is a silicone rubber that contains a conductive filler.

[0061] The silicone rubber-based hardening composition according to the present embodiment can contain a vinyl group-containing organopolysiloxane (A). The vinyl group-containing organopolysiloxane (A) is a polymer that is the main component of the silicone rubber-based hardening composition according to the present embodiment.

[0062] The insulating silicone rubber-based curable composition and the conductive silicone rubber-based curable composition may contain the same type of vinyl group-containing linear organopolysiloxane. The same type of vinyl group-containing linear organopolysiloxane may be different in the amount of vinyl groups in the molecule, the molecular weight distribution, or the amount of vinyl groups added, as long as it contains at least the same vinyl groups as functional groups and has a linear shape. The insulating silicone rubber-based hardenable composition and the conductive silicone rubber-based hardenable composition may further contain different vinyl group-containing organopolysiloxanes.

[0063] The vinyl group-containing organopolysiloxane (A) can contain a vinyl group-containing linear organopolysiloxane (A1) having a linear structure.

[0064] The vinyl group-containing linear organopolysiloxane (A1) has a linear structure and contains vinyl groups, and these vinyl groups become crosslinking points during curing.

[0065] The vinyl group content of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but for example, it is preferable that the vinyl group content is 15 mol% or less, and more preferably 0.01 to 12 mol%, and that the vinyl group content is two or more in the molecule. This optimizes the amount of vinyl groups in the vinyl group-containing linear organopolysiloxane (A1), and ensures the formation of a network with each component described below. In this embodiment, "to" means that the numerical values ​​at both ends are included.

[0066] In this specification, the vinyl group content refers to the mol % of vinyl group-containing siloxane units when all units constituting the vinyl group-containing linear organopolysiloxane (A1) are taken as 100 mol %, where it is considered that there is one vinyl group per vinyl group-containing siloxane unit.

[0067] The degree of polymerization of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but is, for example, preferably within the range of about 1000 to 10000, and more preferably about 2000 to 5000. The degree of polymerization can be determined, for example, as the polystyrene-equivalent number average degree of polymerization (or number average molecular weight) measured by GPC (gel permeation chromatography) using chloroform as a developing solvent.

[0068] Furthermore, the specific gravity of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but is preferably in the range of about 0.9 to 1.1.

[0069] By using a vinyl group-containing linear organopolysiloxane (A1) having a degree of polymerization and specific gravity within the above ranges, it is possible to improve the heat resistance, flame retardancy, chemical stability, etc. of the resulting silicone rubber.

[0070] As the vinyl group-containing linear organopolysiloxane (A1), those having a structure represented by the following formula (1) are particularly preferred.

[0071] [ka]

[0072] In formula (1), R 1is a substituted or unsubstituted alkyl group, alkenyl group, aryl group, or a hydrocarbon group consisting of a combination thereof, each having 1 to 10 carbon atoms. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, and a propyl group, with a methyl group being preferred. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, and a butenyl group, with a vinyl group being preferred. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

[0073] Also, R 2 is a substituted or unsubstituted alkyl group, alkenyl group, aryl group, or a hydrocarbon group consisting of a combination thereof, each having 1 to 10 carbon atoms. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among these, a methyl group is preferable. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, and a butenyl group. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

[0074] Also, R 3 is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group consisting of a combination thereof. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among these, a methyl group is preferable. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group.

[0075] Furthermore, R in formula (1) 1 and R 2 Examples of the substituent of R include a methyl group and a vinyl group. 3 Examples of the substituent include a methyl group.

[0076] In addition, in formula (1), multiple R 1 are independent of each other and may be different or the same. 2 , and R 3 The same applies to.

[0077] Furthermore, m and n are the numbers of repeating units constituting the vinyl group-containing linear organopolysiloxane (A1) represented by formula (1), where m is an integer of 0 to 2000 and n is an integer of 1000 to 10000. m is preferably 0 to 1000 and n is preferably 2000 to 5000.

[0078] A specific example of the structure of the vinyl-containing linear organopolysiloxane (A1) represented by formula (1) is that represented by the following formula (1-1).

[0079] [ka]

[0080] In formula (1-1), R 1 and R 2 are each independently a methyl group or a vinyl group, and at least one of them is a vinyl group.

[0081] Furthermore, the vinyl group-containing linear organopolysiloxane (A1) preferably contains a first vinyl group-containing linear organopolysiloxane (A1-1) having two or more vinyl groups in the molecule and a vinyl group content of 0.4 mol% or less, and a second vinyl group-containing linear organopolysiloxane (A1-2) having a vinyl group content of 0.5 to 15 mol%. By combining the first vinyl group-containing linear organopolysiloxane (A1-1) having a general vinyl group content as a raw rubber that is a raw material for silicone rubber, and the second vinyl group-containing linear organopolysiloxane (A1-2) having a high vinyl group content, the vinyl groups can be unevenly distributed, and the crosslinking density can be more effectively formed in the crosslinked network of the silicone rubber. As a result, the tear strength of the silicone rubber can be more effectively increased.

[0082] Specifically, the vinyl group-containing linear organopolysiloxane (A1) may be, for example, a vinyl group-containing linear organopolysiloxane represented by the above formula (1-1), 1 is a vinyl group and / or R2 a first vinyl group-containing linear organopolysiloxane (A1-1) having two or more units in the molecule each of which is a vinyl group and containing 0.4 mol % or less of a unit represented by R 1 is a vinyl group and / or R 2 It is preferable to use a second vinyl group-containing linear organopolysiloxane (A1-2) containing 0.5 to 15 mol % of units in which the vinyl group is present.

[0083] The first vinyl group-containing linear organopolysiloxane (A1-1) preferably has a vinyl group content of 0.01 to 0.2 mol %, and the second vinyl group-containing linear organopolysiloxane (A1-2) preferably has a vinyl group content of 0.8 to 12 mol %.

[0084] Furthermore, when the first vinyl group-containing linear organopolysiloxane (A1-1) and the second vinyl group-containing linear organopolysiloxane (A1-2) are combined and blended, the ratio of (A1-1) to (A1-2) is not particularly limited, but for example, the weight ratio of (A1-1):(A1-2) is preferably 50:50 to 95:5, and more preferably 80:20 to 90:10.

[0085] The first and second vinyl group-containing linear organopolysiloxanes (A1-1) and (A1-2) may each be used alone or in combination of two or more.

[0086] The vinyl group-containing organopolysiloxane (A) may also contain a vinyl group-containing branched organopolysiloxane (A2) having a branched structure.

[0087] <<Organohydrogenpolysiloxane (B)>> The silicone rubber-based hardenable composition of the present embodiment may contain a crosslinking agent. The crosslinking agent may contain an organohydrogenpolysiloxane (B). The organohydrogenpolysiloxane (B) is classified into a linear organohydrogenpolysiloxane (B1) having a linear structure and a branched organohydrogenpolysiloxane (B2) having a branched structure, and may contain either one or both of these.

[0088] The insulating silicone rubber-based curable composition and the conductive silicone rubber-based curable composition may contain the same type of crosslinking agent. The same type of crosslinking agent may have at least a common structure such as a linear structure or a branched structure, and may have different molecular weight distributions in the molecule or different functional groups, or may be added in different amounts. The insulating silicone rubber-based hardenable composition and the conductive silicone rubber-based hardenable composition may further contain different crosslinking agents.

[0089] The linear organohydrogenpolysiloxane (B1) has a linear structure and a structure in which hydrogen is directly bonded to Si (≡Si-H), and is a polymer that undergoes a hydrosilylation reaction with the vinyl groups of the vinyl group-containing organopolysiloxane (A) and with vinyl groups of components blended into the silicone rubber-based curable composition, thereby crosslinking these components.

[0090] The molecular weight of the linear organohydrogenpolysiloxane (B1) is not particularly limited, but for example, the weight average molecular weight is preferably 20,000 or less, and more preferably 1,000 or more and 10,000 or less.

[0091] The weight average molecular weight of the linear organohydrogenpolysiloxane (B1) can be measured, for example, by polystyrene conversion in gel permeation chromatography (GPC) using chloroform as a developing solvent.

[0092] Furthermore, it is usually preferred that the linear organohydrogenpolysiloxane (B1) does not have a vinyl group, which can reliably prevent the crosslinking reaction from proceeding within the molecule of the linear organohydrogenpolysiloxane (B1).

[0093] As the linear organohydrogenpolysiloxane (B1) as described above, for example, one having a structure represented by the following formula (2) is preferably used.

[0094] [ka]

[0095] In formula (2), R 4 is a substituted or unsubstituted alkyl group, alkenyl group, aryl group, a hydrocarbon group combining these groups, or a hydride group having 1 to 10 carbon atoms. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, etc., and among these, a methyl group is preferable. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, a butenyl group, etc. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

[0096] Also, R 5 is a substituted or unsubstituted alkyl group, alkenyl group, aryl group, a hydrocarbon group combining these groups, or a hydride group having 1 to 10 carbon atoms. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among these, a methyl group is preferable. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, and a butenyl group. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

[0097] In addition, in formula (2), multiple R 4 are independent of each other and may be different or the same. 5 The same applies to R. 4 and R 5 At least two of these are hydride groups.

[0098] Also, R 6is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group combining these. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among these, a methyl group is preferable. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group. 6 are independent of each other and may be different from each other or may be the same.

[0099] In addition, R in formula (2) 4 ,R 5 ,R 6 Examples of the substituent include a methyl group and a vinyl group, and from the viewpoint of preventing an intramolecular crosslinking reaction, a methyl group is preferred.

[0100] Furthermore, m and n are the numbers of repeating units constituting the linear organohydrogenpolysiloxane (B1) represented by formula (2), where m is an integer of 2 to 150 and n is an integer of 2 to 150. Preferably, m is an integer of 2 to 100 and n is an integer of 2 to 100.

[0101] The linear organohydrogenpolysiloxane (B1) may be used alone or in combination of two or more kinds.

[0102] Since the branched organohydrogenpolysiloxane (B2) has a branched structure, it forms regions with high crosslink density, and is a component that greatly contributes to the formation of a sparsely-dense structure of crosslink density in the silicone rubber system. Also, like the linear organohydrogenpolysiloxane (B1), it has a structure in which hydrogen is directly bonded to Si (≡Si-H), and undergoes a hydrosilylation reaction with the vinyl groups of the vinyl group-containing organopolysiloxane (A) and with the vinyl groups of the components blended in the silicone rubber-based hardening composition, forming a polymer that crosslinks these components.

[0103] The specific gravity of the branched organohydrogenpolysiloxane (B2) is in the range of 0.9 to 0.95.

[0104] Furthermore, it is usually preferred that the branched organohydrogenpolysiloxane (B2) does not have a vinyl group, which can reliably prevent the crosslinking reaction from proceeding within the molecule of the branched organohydrogenpolysiloxane (B2).

[0105] As the branched organohydrogenpolysiloxane (B2), one represented by the following average composition formula (c) is preferred.

[0106] Average composition formula (c) (H a (R 7 ) 3-a SiO 1 / 2 ) m (SiO 4 / 2 ) n (In formula (c), R 7 is a monovalent organic group, a is an integer ranging from 1 to 3, and m is H a (R 7 ) 3-a SiO 1 / 2 The number of units, n, is SiO 4 / 2 (the number of units)

[0107] In formula (c), R 7 is a monovalent organic group, preferably a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, an aryl group, or a hydrocarbon group consisting of a combination thereof. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among these, a methyl group is preferred. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

[0108] In formula (c), a is the number of hydride groups (hydrogen atoms directly bonded to Si) and is an integer ranging from 1 to 3, and preferably 1.

[0109] In addition, in formula (c), m is H a (R 7 ) 3-a SiO 1 / 2 The number of units, n, is SiO 4 / 2 It is the number of units.

[0110] The branched organohydrogenpolysiloxane (B2) has a branched structure. The linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2) differ in that their structures are linear or branched, and the number of alkyl groups R bonded to Si (R / Si) when the number of Si is 1 is in the range of 1.8 to 2.1 for the linear organohydrogenpolysiloxane (B1) and 0.8 to 1.7 for the branched organohydrogenpolysiloxane (B2).

[0111] Since the branched organohydrogenpolysiloxane (B2) has a branched structure, for example, when heated in a nitrogen atmosphere to 1000° C. at a heating rate of 10° C. / min, the amount of residue is 5% or more. In contrast, since the linear organohydrogenpolysiloxane (B1) is linear, the amount of residue after heating under the above conditions is almost zero.

[0112] Specific examples of the branched organohydrogenpolysiloxane (B2) include those having a structure represented by the following formula (3).

[0113] [ka]

[0114] In formula (3), R 7 R is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group combining these, or a hydrogen atom. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among these, a methyl group is preferable. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group. 7 Examples of the substituent include a methyl group.

[0115] In addition, in formula (3), multiple R 7 are independent of each other and may be different from each other or may be the same.

[0116] In addition, in formula (3), "-O-Si≡" indicates that Si has a branched structure extending three-dimensionally.

[0117] The branched organohydrogenpolysiloxane (B2) may be used alone or in combination of two or more kinds.

[0118] In addition, the amount of hydrogen atoms (hydride groups) directly bonded to Si in the linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2) is not particularly limited. However, in the silicone rubber-based curable composition, the total amount of hydride groups in the linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2) is preferably 0.5 to 5 moles, more preferably 1 to 3.5 moles, per mole of vinyl group in the vinyl group-containing linear organopolysiloxane (A1). This ensures that a crosslinked network is formed between the linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2) and the vinyl group-containing linear organopolysiloxane (A1).

[0119] <<Silica particles (C)>> The silicone rubber-based hardening composition according to the present embodiment contains a non-conductive filler. The non-conductive filler may contain silica particles (C) as necessary. This can improve the hardness and mechanical strength of the elastomer.

[0120] The insulating silicone rubber-based curable composition and the conductive silicone rubber-based curable composition may contain the same type of non-conductive filler. The non-conductive fillers of the same type may have at least a common constituent material, and may differ in particle size, specific surface area, surface treatment agent, or the amount of the surface treatment agent added. The insulating silicone rubber-based curable composition and the conductive silicone rubber-based curable composition may further contain different silane coupling agents.

[0121] The silica particles (C) are not particularly limited, but for example, fumed silica, calcined silica, precipitated silica, etc. may be used. These may be used alone or in combination of two or more kinds.

[0122] The silica particles (C) have a specific surface area, as measured by the BET method, of, for example, 50 to 400 m 2 / g, and 100 to 400m 2 / g is more preferable. The average primary particle size of the silica particles (C) is, for example, preferably from 1 to 100 nm, and more preferably from about 5 to 20 nm.

[0123] By using silica particles (C) having a specific surface area and average particle size within this range, it is possible to improve the hardness and mechanical strength, particularly the tensile strength, of the silicone rubber that is formed.

[0124] <<Silane coupling agent (D)>> The silicone rubber-based hardenable composition of this embodiment may contain a silane coupling agent (D). The silane coupling agent (D) may have a hydrolyzable group. The hydrolyzable group is hydrolyzed by water to become a hydroxyl group, and the hydroxyl group undergoes a dehydration condensation reaction with the hydroxyl group on the surface of the silica particles (C), thereby modifying the surface of the silica particles (C).

[0125] The insulating silicone rubber-based curable composition and the conductive silicone rubber-based curable composition may contain the same type of silane coupling agent. The same type of silane coupling agent may have at least a common functional group, but may have different other functional groups in the molecule or different amounts added. The insulating silicone rubber-based curable composition and the conductive silicone rubber-based curable composition may further contain different silane coupling agents.

[0126] In addition, the silane coupling agent (D) may contain a silane coupling agent having a hydrophobic group. This provides the surface of the silica particles (C) with this hydrophobic group, so that the cohesive force of the silica particles (C) in the silicone rubber-based curable composition and thus in the silicone rubber is reduced (there is less cohesion due to hydrogen bonds caused by silanol groups), and as a result, it is presumed that the dispersibility of the silica particles (C) in the silicone rubber-based curable composition is improved. This increases the interface between the silica particles (C) and the rubber matrix, and the reinforcing effect of the silica particles (C) is enhanced. Furthermore, it is presumed that the slipperiness of the silica particles (C) in the matrix is ​​improved during deformation of the rubber matrix. And, due to the improvement in the dispersibility and slipperiness of the silica particles (C), the mechanical strength (for example, tensile strength, tear strength, etc.) of the silicone rubber due to the silica particles (C) is improved.

[0127] Furthermore, the silane coupling agent (D) may contain a silane coupling agent having a vinyl group. This allows the vinyl group to be introduced onto the surface of the silica particles (C). Therefore, when the silicone rubber-based curable composition is cured, that is, when the vinyl group of the vinyl group-containing organopolysiloxane (A) and the hydride group of the organohydrogenpolysiloxane (B) undergo a hydrosilylation reaction to form a network (crosslinked structure), the vinyl group of the silica particles (C) also participates in the hydrosilylation reaction with the hydride group of the organohydrogenpolysiloxane (B), so that the silica particles (C) are also incorporated into the network. This allows the formed silicone rubber to have a low hardness and a high modulus.

[0128] As the silane coupling agent (D), a silane coupling agent having a hydrophobic group and a silane coupling agent having a vinyl group can be used in combination.

[0129] An example of the silane coupling agent (D) is one represented by the following formula (4).

[0130] Yn -Si-(X) 4-n (4) In the above formula (4), n represents an integer of 1 to 3. Y represents any functional group having a hydrophobic group, a hydrophilic group, or a vinyl group, and when n is 1, it is a hydrophobic group, and when n is 2 or 3, at least one of them is a hydrophobic group. X represents a hydrolyzable group.

[0131] The hydrophobic group is an alkyl group having 1 to 6 carbon atoms, an aryl group, or a hydrocarbon group formed by combining these groups, and examples thereof include a methyl group, an ethyl group, a propyl group, and a phenyl group, with a methyl group being particularly preferred.

[0132] In addition, the hydrophilic group may be, for example, a hydroxyl group, a sulfonic acid group, a carboxyl group, or a carbonyl group, and among these, a hydroxyl group is particularly preferred. Note that, although a hydrophilic group may be included as a functional group, it is preferable that the hydrophilic group is not included from the viewpoint of imparting hydrophobicity to the silane coupling agent (D).

[0133] Further, examples of the hydrolyzable group include alkoxy groups such as methoxy and ethoxy groups, chloro groups, and silazane groups. Among these, silazane groups are preferred because of their high reactivity with the silica particles (C). In addition, those having a silazane group as a hydrolyzable group can be easily obtained by adding (Y n -Si-) structures.

[0134] Specific examples of the silane coupling agent (D) represented by the above formula (4) are as follows. Examples of the functional group having a hydrophobic group include alkoxysilanes such as methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, and decyltrimethoxysilane; chlorosilanes such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, and phenyltrichlorosilane; and hexamethyldisilazane.Among these, the silane coupling agent having a trimethylsilyl group, which includes one or more selected from the group consisting of hexamethyldisilazane, trimethylchlorosilane, trimethylmethoxysilane, and trimethylethoxysilane, is preferred.

[0135] Examples of the functional group having a vinyl group include alkoxysilanes such as methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, and vinylmethyldimethoxysilane; chlorosilanes such as vinyltrichlorosilane and vinylmethyldichlorosilane; and divinyltetramethyldisilazane.Among these, preferred is a silane coupling agent having a vinyl group-containing organosilyl group, including one or more selected from the group consisting of methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, divinyltetramethyldisilazane, vinyltriethoxysilane, vinyltrimethoxysilane, and vinylmethyldimethoxysilane.

[0136] Furthermore, when the silane coupling agent (D) contains two types of silane coupling agents, a silane coupling agent having a trimethylsilyl group and a silane coupling agent having a vinyl group-containing organosilyl group, it is preferable that the silane coupling agent having the hydrophobic group is hexamethyldisilazane, and the silane coupling agent having the vinyl group is divinyltetramethyldisilazane.

[0137] When the silane coupling agent (D1) having a trimethylsilyl group and the silane coupling agent (D2) having a vinyl-containing organosilyl group are used in combination, the ratio of (D1) to (D2) is not particularly limited, but for example, the weight ratio of (D1):(D2) is 1:0.001 to 1:0.35, preferably 1:0.01 to 1:0.20, more preferably 1:0.03 to 1:0.15. By setting the weight ratio in such a range, the desired physical properties of the silicone rubber can be obtained. Specifically, the dispersibility of silica in the rubber and the crosslinking property of the rubber can be balanced.

[0138] In this embodiment, the lower limit of the content of the silane coupling agent (D) is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, based on 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A). The upper limit of the content of the silane coupling agent (D) is preferably 100% by mass or less, more preferably 80% by mass or less, and even more preferably 40% by mass or less, based on 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A). By making the content of the silane coupling agent (D) equal to or greater than the lower limit, the adhesion between the columnar portion containing the elastomer and the conductive resin layer can be improved. This also contributes to improving the mechanical strength of the silicone rubber. Furthermore, by making the content of the silane coupling agent (D) equal to or less than the upper limit, the silicone rubber can have appropriate mechanical properties.

[0139] <<Platinum or platinum compounds (E)>> The silicone rubber-based curable composition according to this embodiment may contain a catalyst. The catalyst may contain platinum or a platinum compound (E). The platinum or platinum compound (E) is a catalyst component that acts as a catalyst during curing. The amount of platinum or platinum compound (E) added is a catalytic amount.

[0140] The insulating silicone rubber-based curable composition and the conductive silicone rubber-based curable composition may contain the same type of catalyst. The same type of catalyst may have at least a common component material, and may contain different compositions in the catalyst, and the amounts of the catalyst added may be different. The insulating silicone rubber-based curable composition and the conductive silicone rubber-based curable composition may further contain different catalysts.

[0141] As the platinum or platinum compound (E), known substances can be used, such as platinum black, platinum supported on silica or carbon black, chloroplatinic acid or an alcohol solution of chloroplatinic acid, a complex salt of chloroplatinic acid and an olefin, and a complex salt of chloroplatinic acid and a vinylsiloxane.

[0142] The platinum or platinum compound (E) may be used alone or in combination of two or more kinds.

[0143] In this embodiment, the content of platinum or platinum compound (E) in the silicone rubber-based curable composition means a catalytic amount and can be set as appropriate, but specifically, the amount is such that the platinum group metal is 0.01 to 1000 ppm by weight, and preferably 0.1 to 500 ppm, per 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A), the silica particles (C), and the silane coupling agent (D). By making the content of platinum or platinum compound (E) equal to or greater than the lower limit, the silicone rubber-based hardening composition can be hardened at an appropriate rate. In addition, by making the content of platinum or platinum compound (E) equal to or less than the upper limit, it is possible to reduce the production cost.

[0144] <<Water(F)>> Furthermore, the silicone rubber-based hardenable composition according to this embodiment may contain water (F) in addition to the above components (A) to (E).

[0145] Water (F) functions as a dispersion medium for dispersing each component contained in the silicone rubber-based hardening composition, and is also a component that contributes to the reaction between the silica particles (C) and the silane coupling agent (D). Therefore, the silica particles (C) and the silane coupling agent (D) can be more reliably linked to each other in the silicone rubber, and uniform properties can be exhibited overall.

[0146] (Other Ingredients) Furthermore, the silicone rubber-based hardening composition of the present embodiment may further contain other components in addition to the above components (A) to (F), such as inorganic fillers other than the silica particles (C), such as diatomaceous earth, iron oxide, zinc oxide, titanium oxide, barium oxide, magnesium oxide, cerium oxide, calcium carbonate, magnesium carbonate, zinc carbonate, glass wool, and mica, as well as additives such as reaction inhibitors, dispersants, pigments, dyes, antistatic agents, antioxidants, flame retardants, and thermal conductivity improvers.

[0147] The conductive solution (conductive silicone rubber composition) according to this embodiment contains the above-mentioned conductive filler and a solvent in addition to the above-mentioned silicone rubber-based hardenable composition that does not contain a conductive filler.

[0148] As the solvent, various known solvents can be used, including, for example, high boiling point solvents. These may be used alone or in combination of two or more kinds.

[0149] Examples of the solvent include aliphatic hydrocarbons such as pentane, hexane, cyclohexane, heptane, methylcyclohexane, ethylcyclohexane, octane, decane, dodecane, and tetradecane; aromatic hydrocarbons such as benzene, toluene, ethylbenzene, xylene, trifluoromethylbenzene, and benzotrifluoride; ethers such as diethyl ether, diisopropyl ether, dibutyl ether, cyclopentyl methyl ether, cyclopentyl ethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, 1,4-dioxane, 1,3-dioxane, and tetrahydrofuran; haloalkanes such as dichloromethane, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-trichloroethane, and 1,1,2-trichloroethane; carboxylic acid amides such as N,N-dimethylformamide and N,N-dimethylacetamide; and sulfoxides such as dimethyl sulfoxide and diethyl sulfoxide. These may be used alone or in combination of two or more.

[0150] The conductive solution can have a viscosity suitable for various coating methods such as spray coating and dip coating by adjusting the solid content in the solution.

[0151] In addition, when the conductive solution contains the conductive filler and the silica particles (C), the lower limit of the content of the silica particles (C) contained in the conductive resin layer 30 can be, for example, 1 mass% or more, preferably 3 mass% or more, and more preferably 5 mass% or more, based on 100 mass% of the total amount of the silica particles (C) and the conductive filler. This can improve the mechanical strength of the conductive resin layer 30. On the other hand, the upper limit of the content of the silica particles (C) contained in the conductive resin layer 30 is, for example, 20 mass% or less, preferably 15 mass% or less, and more preferably 10 mass% or less, based on 100 mass% of the total amount of the silica particles (C) and the conductive filler. This can balance the conductivity of the conductive resin layer 30 with the mechanical strength and flexibility.

[0152] The conductive solution is dried by heating as necessary to obtain a conductive silicone rubber. The conductive silicone rubber may be configured not to contain silicone oil, which can prevent the silicone oil from bleeding out onto the surface of the conductive resin layer 30 and thus prevent the conductivity from decreasing.

[0153] An example of a method for manufacturing the biological electrode 100 of this embodiment can include the following steps. First, the silicone rubber-based hardening composition is molded under heat and pressure using a metal mold to obtain a molded body having the plate-like supporting portion 10 and the columnar portion 20 (molding step).

[0154] Next, the conductive wire 60 is inserted into the columnar portion 20 (conductive wire insertion process). For example, a needle can be used to pass the conductive wire 60 through the columnar portion 20. Mass production is possible by using a sewing machine. Alternatively, during the molding step, insert molding may be used in which the silicone rubber-based hardening composition is introduced into the molding space in which the conductive wires 60 are disposed, and molded under pressure and heat.

[0155] Next, the tip 26 of the columnar section 20 of the obtained molded body is dip-coated in the conductive solution and then heated and dried (tip coating step). The conductive solution may be spray-coated on the tip 26 and then heated and dried. This forms a conductive resin layer 30 that covers the tip 22 of the columnar section 20. After that, a post-cure (annealing step) is performed at a specified temperature and under specified temperature conditions. In this manner, the biological electrode 100 can be manufactured.

[0156] As an example of another manufacturing method, the method may include the following steps. In the molding step, for example, a mold having a plurality of recesses is used to obtain a molded sheet on which a plurality of sets of columnar portions 20 and plate-like supporting portions 10 are formed. Next, in the conductive wire insertion step, conductive wires 60 are inserted into the multiple columnar portions 20 in the molded sheet. Next, in the tip covering step, a conductive resin layer 30 is formed to cover at least the tips 22 of the tip portions 26 of the multiple columnar portions 20 in the molded sheet. Next, an individualized molded body including the plate-shaped support portion 10, the columnar portion 20, the conductive wire 60, and the conductive resin layer 30 is taken out from the molded body sheet (singulation process). As a method for taking out the individualized molded body, for example, a method of punching out the molded body sheet may be adopted. Thereafter, each individual molded body is post-cured in an annealing step. In this manner, the biological electrode 100 can be manufactured.

[0157] After the molding step and before the conductive wire insertion step, the tip 26 of the columnar section 20 may be cut into a desired shape to form an inclined surface. Alternatively, instead of cutting, the tip 26 of the columnar section 20 may be formed into an inclined surface by molding with a mold.

[0158] The bioelectrode 100 of this embodiment can detect bioelectrical signals generated by biological activities of the brain, heart, muscles, nerves, etc. This bioelectrode 100 is flexible and has excellent wearability on the scalp, so it can be suitably used as an electrode for measuring electroencephalograms.

[0159] An electroencephalogram measuring electrode using the biological electrode 100 is expected to be used in BMI (Brain Machine Interface).

[0160] Furthermore, the bioelectrode 100 can be used as a dry sensor that is easy to use and can be used repeatedly, rather than a wet sensor that requires application of gel to the measurement area. Furthermore, compared to a spring-loaded metal pin-type dry sensor, the bioelectrode 100 has flexibility that can reduce pain and discomfort for the subject (user). Furthermore, the bioelectrode 100 can be mounted on a wearable device due to its miniaturization.

[0161] The biosensor of this embodiment will be described. FIG. 2 is a schematic diagram showing an overview of an example of a biosensor 200. As shown in FIG. The biosensor 200 of this embodiment includes a bioelectrode 100, and may further include an external connection part 110 connected to the bioelectrode 100.

[0162] The external connection portion 110 may be removably attached to the plate-shaped support portion 10 of the biological electrode 100, or may be fixed to the plate-shaped support portion 10.

[0163] The external connection part 110 is stronger than silicone rubber in terms of durability, and at least includes an external electrode part having electrical conductivity. The external electrode part is made of, for example, metal. This external electrode part can send a bioelectric signal detected by the bioelectrode 100 to an external electronic component. The shape of the external electrode part is not particularly limited, but is configured so that a connector that can be connected to an electronic component or wiring can be attached. For example, the external connection part 110 can be configured as a metallic snap button, and can have a structure that is electrically connected to an external wiring or an electrode of a board by a contact pin.

[0164] The biosensor 200 may further include electronic components that can be electrically connected via the external connection unit 110. Known electronic components can be used depending on various applications, and examples of such electronic components include an amplifier, an AD converter, a CPU, a memory, a communication circuit, a wireless communication unit, an analog filter, a capacitor, a resistor, and a battery. One or more of these components may be modularized on a circuit board. This allows the biosensor 200 to be used as a wearable device. In addition, other sensors such as an acceleration sensor, a temperature sensor, and a pressure sensor may be used in combination as electronic components.

[0165] The biosensor 200 includes one or more than one bioelectrodes 100. The biosensor 200 may be attached to a jig such as headgear or an armband for attachment to a living body.

[0166] The biological signal measuring system of this embodiment will be described. The biosignal measuring system of this embodiment includes a biosensor 200. The biosignal measuring system may be a system (measuring device) that displays, analyzes, or stores data received from the biosensor 200.

[0167] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of the present invention are included in the present invention. EXAMPLES

[0168] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the descriptions of these examples.

[0169] The raw material components shown in Table 1 are as follows:

[0170] (Vinyl-containing organopolysiloxane (A)) (A1-1): First vinyl group-containing linear organopolysiloxane: vinyl group content is 0.04 mol%, Mn=2.2×10 5 , Mw=4,8×10 5 ), a vinyl group-containing dimethylpolysiloxane (structure represented by the above formula (1-1)) synthesized according to the following synthesis scheme 1: (A1-2): Second vinyl group-containing linear organopolysiloxane: vinyl group content is 0.93 mol %, vinyl group-containing dimethylpolysiloxane (structure represented by the above formula (1-1), R 1 and R 2 is a vinyl group)

[0171] (Organohydrogenpolysiloxane (B)) (B): Organohydrogenpolysiloxane: Momentive Corporation, "TC-25D"

[0172] (Silica particles (C)) (C): Silica microparticles (particle size 7 nm, specific surface area 300 m 2 / g), manufactured by Nippon Aerosil Co., Ltd., "AEROSIL300"

[0173] (Silane coupling agent (D)) (D-1): Hexamethyldisilazane (HMDZ), manufactured by Gelest, "HEXAMETHYLDISILAZANE (SIH6110.1)" (D-2): Divinyltetramethyldisilazane, manufactured by Gelest, "1,3-DIVINYLTETRAMETHYLDISILAZANE (SID4612.0)"

[0174] (Platinum or platinum compounds (E)) (E): Platinum or platinum compound: Momentive, "TC-25A"

[0175] (Water(F)) (F):Pure water

[0176] (Metal powder (G)) (G1): Silver powder, manufactured by Tokuriki Chemical Laboratory, product name "TC-101", median diameter d 50 : 8.0μm, aspect ratio 16.4, average major axis 4.6μm

[0177] (Synthesis of vinyl group-containing organopolysiloxane (A)) [Synthesis Scheme 1: Synthesis of First Vinyl Group-Containing Linear Organopolysiloxane (A1-1)] A first vinyl group-containing linear organopolysiloxane (A1-1) was synthesized according to the following formula (5). That is, 74.7 g (252 mmol) of octamethylcyclotetrasiloxane and 0.1 g of potassium siliconate were placed in a 300 mL separable flask equipped with a cooling tube and stirring blade and replaced with Ar gas, and the temperature was raised and the mixture was stirred at 120° C. for 30 minutes. At this time, an increase in viscosity was confirmed. The mixture was then heated to 155° C. and stirred for 3 hours, after which 0.1 g (0.6 mmol) of 1,3-divinyltetramethyldisiloxane was added and the mixture was stirred at 155° C. for an additional 4 hours. After four hours, the mixture was diluted with 250 mL of toluene and then washed three times with water. The washed organic layer was washed several times with 1.5 L of methanol for reprecipitation purification, and the oligomer and polymer were separated. The resulting polymer was dried overnight at 60°C under reduced pressure to obtain a first vinyl group-containing linear organopolysiloxane (A1-1) (Mn = 2.2 × 10 5 , Mw=4,8×10 5 The vinyl group content calculated from H-NMR spectrum measurement was 0.04 mol %.

[0178] [ka]

[0179] [Synthesis Scheme 2: Synthesis of the second vinyl-containing linear organopolysiloxane (A1-2)] In the synthesis process of (A1-1) above, except that 0.86g (2.5mmol) of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane was used in addition to 74.7g (252mmol) of octamethylcyclotetrasiloxane, the second vinyl-containing linear organopolysiloxane (A1-2) was synthesized as shown in the following formula (6) by the same synthesis process as (A1-1). The vinyl content calculated by H-NMR spectrum measurement was 0.93 mol%.

[0180] [ka]

[0181] <Preparation of Silicone Rubber-Based Curable Composition> A silicone rubber-based hardenable composition was prepared as follows. First, a mixture of 90% vinyl group-containing organopolysiloxane (A), silane coupling agent (D), and water (F) was pre-kneaded in the proportions shown in Table 1 below, and then silica particles (C) were added to the mixture and further kneaded to obtain a kneaded product (silicone rubber compound). Here, the kneading after the addition of the silica particles (C) was carried out through a first step of kneading for 1 hour under conditions of 60 to 90°C in a nitrogen atmosphere for the coupling reaction, and a second step of kneading for 2 hours under conditions of 160 to 180°C in a reduced pressure atmosphere for the removal of the by-product (ammonia). Thereafter, the mixture was cooled, and the remaining 10% of the vinyl group-containing organopolysiloxane (A) was added in two portions and kneaded for 20 minutes. Next, organohydrogenpolysiloxane (B), platinum or a platinum compound (E) were added to 100 parts by weight of the obtained kneaded product (silicone rubber compound) in the proportions shown in Table 1 below, and the mixture was kneaded with a roll to obtain a silicone rubber-based curable composition A (elastomer composition).

[0182] [Table 1]

[0183] <Preparation of conductive solution for dip coating> The obtained silicone rubber-based curable composition A (13.7 parts by weight) was immersed in 31.8 parts by weight of decane (solvent), then stirred with a planetary centrifugal mixer, 54.5 parts by weight of metal powder (G1) was added, and the mixture was kneaded with a triple roll mill to obtain a conductive paste (conductive solution for dip coating).

[0184] <Preparation of conductive solution for spray painting> 13.7 parts by weight of the obtained silicone rubber-based hardening composition A was immersed in 31.8 parts by weight of decane (solvent), then stirred with a planetary centrifugal mixer, 54.5 parts by weight of metal powder (G1) was added, and kneaded with a triple roll to obtain a resin varnish. Then, 2.5 times the amount of the resin varnish was added with decane, and the mixture was stirred and diluted with a planetary centrifugal mixer to obtain a conductive solution for spray coating.

[0185] <Preparation of bioelectrodes> Example 1 The silicone rubber-based curable composition A obtained above was cured by heating at 180°C and 10 MPa for 10 minutes using a mold having multiple molding spaces (recesses) for the plate-shaped support parts and the approximately conical columnar parts, to obtain molded bodies in which the plate-shaped support parts and the columnar parts were integrated in each recess (molding process). A conductive wire A (manufactured by Mitsufuji, AGposs, thickness: 100d / 34f, tensile elongation at break: 29.3%) was passed through the inside of the columnar portion of the obtained molded body using a sewing needle (conductive wire insertion step). Next, the tip of the columnar part of the molded body (when the total length of the columnar part is L, the region approximately 1 / 2L from the tip) and the other surface of the plate-like support part were dipped into the above-mentioned <conductive solution for dip coating> and heated and dried at 120°C for 30 minutes (tip coating process). Then, post-curing was carried out at 140° C. for 2 hours (annealing step). As a result of the above, a biological electrode A having a substantially conical columnar portion 20 on a plate-shaped supporting portion 10 as shown in FIG. 1 was obtained. In the biological electrode A, the inclination angle θ was 53 degrees, the radius of the tip 22 was 1.5 mm, the tip of the conductive wire 60 protruded beyond the tip 22 of the columnar portion 20 and was covered with a conductive resin layer 30.

[0186] Example 2 A biological electrode B was obtained in the same manner as in Example 1, except that conductive wire B (manufactured by Mitsufuji, AGposs, thickness: 70d / 24f, tensile breaking elongation: 27.9%) was used instead of conductive wire A.

[0187] Example 3 A biological electrode C was obtained in the same manner as in Example 1, except that conductive wire C (manufactured by Nippon Seisen Co., Ltd., metal fiber stainless steel fiber Naslon, SUS304, thickness: 0.22 mm, tensile breaking elongation: 1.6%) was used instead of conductive wire A.

[0188] Comparative Example 1 In the same manner as in Example 1, a molded article for <Preparation of a biological electrode> was obtained. The conductive solution for spray coating was sprayed onto the entire surface of the obtained molded body without performing the conductive wire insertion process, and the molded body was dried by heating at 120°C for 30 minutes to form a conductive resin layer on the entire surface of the molded body. After that, the molded body was post-cured at 140°C for 2 hours to obtain a bioelectrode D.

[0189] The obtained biological electrodes A to D were evaluated for the following evaluation items. The evaluation results are shown in Table 2.

[0190] (Fitting stability) The above <Preparation of bioelectrode> was carried out in the same manner as in Example 1, and a 2 mm diameter steel ball (high carbon chromium bearing steel material manufactured by Tsubaki Nakashima) was attached to the tip so as to connect to the conductive wire, thereby obtaining a bioelectrode E of Comparative Example 2.

[0191] When the tip of the columnar part of the bioelectrode E of Comparative Example 2 was pressed against the back of the subject's head, and the probe of a push-pull gauge (manufactured by Nidec-Shimpo Corporation, product name: digital force gauge FGJN-2) was pressed against the other side of the bioelectrode E opposite the tip with a constant load of 15 N, the subject evaluated that it felt pain and could only tolerate it for a short time.

[0192] In contrast, when the biomedical electrodes A to C of Examples 1 to 3 were used, the evaluation indicated that there was a contact sensation, but it was not bothersome, or no pain was felt. Therefore, it was found that the biomedical electrodes A to C of Examples 1 to 3 were superior in wearing stability to the biomedical electrode E of Comparative Example 2.

[0193] [Table 2]

[0194] (Measurement stability) <Construction of an EEG measuring system> As shown in FIG. 2, an external connection part 110 (a metal snap button having a structure in which the end of the cable can be freely attached) was attached to the other surface 14 of the bioelectrode 100 obtained in the above <Preparation of a bioelectrode> via a conductive resin layer. A disposable electrode cord (Miyuki Giken Co., Ltd., product name: AP-C131-015) and a portable electroencephalograph (Miyuki Giken Co., Ltd., product name: PolymateMini AP-108) were electrically connected to this external connection part 110 in this order to prepare an electroencephalogram measuring system. The portable electroencephalograph was connected to a laptop computer via Bluetooth, and the contact resistance with the head was obtained using a waveform display program (Miyuki Giken Co., Ltd., product name: Mobile Acquisition Monitor). The left earlobe was used as the ground and reference.

[0195] Next, the subjects were fitted with headgear for measuring EEG (headgear with node placement based on the international 10 / 20 system, molded using a 3D printer). Then, the tip 26 of the bioelectrode 100 was brought into contact with the back of the head of the subject, and the tip 26 of the columnar portion 20 of the bioelectrode 100 was pressed against the back of the head (0z) of the subject. At first, the probe of a push-pull gauge (manufactured by Nidec-Shimpo Corporation, product name: digital force gauge FGJN-2) was pressed against the external connection portion 110 of the bioelectrode 100 with a load of 7N. The force was gradually released, and the contact resistance (kΩ) was continuously measured at 5N, 3N, and 1N to evaluate the change in contact resistance with respect to the load. The results are shown in Table 2.

[0196] Considering Table 2, it was found that the biological electrode of Example 1 had a small change in contact resistance (Δ(7N-5N)) at the initial stage of load change, compared to Comparative Example 1.

[0197] From the above, it was found that the biological electrodes A to C of Examples 1 to 3 were superior in attachment stability to the biological electrode E of Comparative Example 2, and superior in measurement stability to the biological electrode D of Comparative Example 1. [Explanation of symbols]

[0198] 10 Plate-shaped support part 12 one side 14 Other side 20 Column part 22 Tip 24 Proximal end 26 Tip 28 Slope 29 Slope 30 Conductive resin layer 60 Conductive Wire 100 Bioelectrodes 110 External connection part 200 Biometric Sensor

Claims

1. An insulating plate-shaped support part; an insulating elastic columnar portion having a substantially conical shape and provided on one surface of the insulating plate-like support portion; a conductive resin layer formed to cover the tip of the insulating elastic columnar portion; a conductive wire electrically connected to the conductive resin layer and disposed inside the insulating elastic columnar portion and the insulating plate-shaped support portion from the distal end side to the proximal end side; an external connection; A biological electrode comprising:

2. A biological electrode according to claim 1, A biological electrode, wherein the tip of the insulating elastic columnar portion is configured in any one of a substantially hemispherical shape, an ellipsoidal shape, a conical shape, a truncated conical shape, a pyramidal shape, and a substantially pyramidal shape.

3. A biological electrode according to claim 1 or 2, A biological electrode, wherein the type A durometer hardness of the surface of the insulating elastic columnar portion, measured at 37°C in accordance with JIS K 6253 (1997), is 15 or more and 65 or less.

4. A biological electrode according to any one of claims 1 to 3, A biological electrode in which the insulating plate-shaped support portion and the insulating elastic columnar portion are formed as an integral member.

5. A biological electrode according to any one of claims 1 to 4, A biological electrode, wherein the conductive wire is made of conductive fiber.

6. A biological electrode according to any one of claims 1 to 5, A biological electrode, wherein the conductive wire is made of a twisted yarn formed by twisting together a plurality of linear conductive fibers.

7. A biological electrode according to claim 6, A biological electrode, wherein the conductive fibers comprise one or more selected from the group consisting of metal fibers, metal-coated fibers, carbon fibers, conductive polymer fibers, conductive polymer-coated fibers, and conductive paste-coated fibers.

8. A biological electrode according to any one of claims 1 to 7, A biological electrode, wherein the insulating elastic columnar portion is made of insulating silicone rubber containing silicone rubber.

9. A biological electrode according to any one of claims 1 to 8, A biological electrode, wherein the conductive resin layer is made of conductive silicone rubber containing a conductive filler and silicone rubber.

10. A biological electrode according to claim 9, A biological electrode, wherein the content of the conductive filler is 30% by mass or more and 90% by mass or less relative to 100% by mass of the silicone rubber.

11. A biological electrode according to claim 9 or 10, A biological electrode, wherein the conductive filler comprises one or more selected from the group consisting of metal particles, silver / silver chloride particles, metal fibers, metal-coated fibers, carbon black, acetylene black, graphite, carbon fibers, carbon nanotubes, conductive polymers, conductive polymer-coated fibers, and metal nanowires.

12. A biological electrode according to any one of claims 1 to 11, A biological electrode used for measuring electroencephalograms.

13. A biosensor comprising a bioelectrode described in any one of claims 1 to 12.

14. A biological signal measurement system comprising the biological sensor described in claim 13.

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