Biosensor electrode, biosensor, and biological signal measurement 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 biological electrode, a biosensor, and a biological signal measurement system.

Background Art

[0002] Various developments have been made on biological electrodes so far. As this type of technology, for example, the technology described in Patent Document 1 is known. Patent Document 1 describes a biological electrode including a base material (a conductive protrusion) made of an elastic body and a structure (a base) formed on the surface of the base material (Claim 1, FIG. 2). This base material is described as being formed by blending a nanocarbon material into an elastic body serving as a base material (paragraph 0068).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, as a result of the study by the present inventor, it has been found that there is room for improvement in terms of measurement stability in the biological electrode described in Patent Document 1 above.

Means for Solving the Problems

[0005] In conventional biological electrodes, a columnar elastic body that contacts the biological surface and functions as a sensor has a conductive layer formed on the entire surface thereof to ensure conduction, or is entirely composed of a conductive member like the base material described in Patent Document 1 above.

[0006] The inventor further studied and found that when measuring the bioelectric potential using a columnar elastic body entirely covered with a conductive member, there may be noise due to large fluctuations in resistance. Although the detailed mechanism is not clear, it is considered that when the columnar elastic body contacts the living body surface and deforms with the outer side in the contraction direction and the inner side in the elongation direction, the resistance values on the surface and near the surface of the elastic columnar part vary greatly between the outer side and the inner side.

[0007] Based on such findings, through further intensive research, it was found that by obtaining the electrical conductivity of the columnar elastic body through a conductive wire passing through its interior, fluctuations in resistance during deformation of the columnar elastic body can be suppressed. Also, by making the tip of the columnar elastic body have a substantially conical shape, it becomes easier to follow the living body surface compared to the case where the tip has a cylindrical shape, and large deformations during contact with the living body are suppressed, so noise is suppressed. As a result, it was found that the measurement stability can be improved, and the present invention was completed.

[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 to cover the tip of the elastic columnar portion, a conductive wire that is electrically connected to the conductive resin layer and is disposed inside the elastic columnar portion from the tip side toward the base end side, A bioelectrode comprising the above is provided.

[0009] Also according to the present invention, a biosensor comprising the above bioelectrode is provided. Also according to the present invention, a biological signal measurement system comprising the above biosensor is provided.

Advantages of the Invention

[0010] According to the present invention, a bioelectrode excellent in measurement stability, a biosensor using the same, and a biological signal measurement system are provided.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0012] In the present embodiment, as shown in the drawings, the directions of front, back, left, right, up, and down will be defined and described. However, this is defined for convenience in order to easily explain the relative relationship of the components. Therefore, it does not limit the directions during the manufacture or use of the product implementing the present invention. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate. Also, the drawings are schematic views and do not match the actual dimensional ratios. In this specification, the term "substantially" means including the range considering manufacturing tolerances, variations, etc. unless otherwise explicitly stated.

[0013] An overview of the living body electrode of the present embodiment will be described. The living body electrode includes a plate-shaped support portion, an elastic columnar portion having a substantially conical shape 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, and a conductive wire that is electrically connected to the conductive resin layer and is disposed inside the elastic columnar portion from the tip side toward the base end side.

[0014] The present inventor obtained the following findings. Hitherto, regarding the conductivity of the elastic columnar portion of the living body electrode, methods of forming the entire surface with a conductive resin layer and methods of configuring the elastic columnar portion itself with a conductive material have been studied. However, it has been found that when in contact with the living body surface, due to the expansion and contraction deformation between the inside and outside of the elastic columnar portion, the resistance of the elastic columnar portion composed of the conductive resin layer or the conductive material fluctuates, and there is a risk of generating noise. Also, when the elastic columnar portion is deformed, there is a risk of disconnection occurring in the conductive resin layer at a portion where the deformation is large.

[0015] On the other hand, a structure for achieving electrical continuity with the conductive wire disposed inside the elastic columnar portion can suppress fluctuations in resistance during deformation as compared with the structure for achieving electrical continuity by the above method. Although the detailed mechanism is not clear, the following can be considered. When contacting the living body surface, the outside of the elastic columnar portion deforms in the shrinking direction and the inside deforms in the tensile direction. At this time, the conductive wire passing through the inside of the elastic columnar portion has relatively smaller deformation and deformation strain compared with the surface or the vicinity of the surface of the elastic columnar portion. For this reason, even when the elastic columnar portion gradually deforms greatly from the contact time, the fluctuation of the resistance value from the initial resistance (contact resistance) is suppressed, so that the generation of noise can be stably suppressed.

[0016] In addition, the columnar elastic portion having a substantially conical shape is more likely to follow the living body surface when contacting the living body surface than the columnar shape structure. Therefore, when the pressing force is the same, large deformation is suppressed. Thereby, an increase in the fluctuation of the contact resistance can be suppressed.

[0017] As described above, the biological electrode of the present embodiment can suppress the generation of noise when contacting the living body, so that it is possible to improve the measurement stability.

[0018] The biological electrode of the present embodiment can detect potential fluctuations from a living body such as brain waves, heartbeat, muscle activity, and nervous system activity. The biological electrode can further include a connector, electronic components, etc., and can constitute a biological sensor that can be connected to an external device. This biological sensor is wearable. By analyzing the biological potential such as brain waves detected from the biological sensor, a biological signal measurement system corresponding to various applications can be constructed.

[0019] Hereinafter, the configuration of the biological electrode of the present embodiment will be described in detail.

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

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

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

[0023] The shape of the plate-shaped support portion 10 in a top view 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, or a hexagon. Rounding (rounding) may be provided at the corners of the polygon. Here, the top view means observing from the top surface direction when looking from the tip 22 of the columnar portion 20 toward the plate-shaped support portion 10.

[0024] One surface 12 of the plate-shaped support portion 10 may be configured as a flat surface, but may 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 portion 10 are in contact. Further, there may be no interface between the plate-shaped support portion 10 and the columnar portion 20, and they 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, on the other surface 14 opposite to the one surface 12, an electrode that can be electrically connected to the connector may be embedded in a state where a part thereof is exposed. Further, 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-like support portion 10 may not be covered with the conductive elastic member.

[0026] The plate-like support portion 10 may be formed as an integral member with the columnar portions 20. That is, the plate-like support portion 10 can be integrally formed of the same resin material as the plurality of columnar portions 20. For example, by molding a curable elastomer composition such as a silicone rubber-based curable composition described later using a mold, a molded body in which the plate-like support portion 10 and the plurality of columnar portions 20 are seamlessly joined can be obtained. Thereby, an elastic molded body excellent in flexibility and strength can be realized.

[0027] Each of the plate-like support portion 10 and the columnar portions 20 can be formed of an insulating silicone rubber (rubber molded body) containing silicone rubber without containing a conductive filler as one of the insulating elastic members.

[0028] The columnar portions 20 may be provided on one or two or more plate-like support portions 10. The shape of the columnar portions 20 in a top view may be 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, or a hexagon. The shape of the columnar portions 20 in a top view and the shape of the plate-like support portion 10 in a top view may be the same. Among these, by setting it as a substantially circular shape, preferably a perfect circle, the measurement stability can be enhanced.

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

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

[0031] The tip 22 of the columnar part 20 may be provided with a roundness (rounding). Thereby, it is possible to suppress catching on the living body during contact and improve the wearing stability. In addition, since the mold release after molding becomes easy, the manufacturing stability can be enhanced. In one of the cross-sectional views passing through the tip 22, the roundness of the tip 22 is, for example, from 0.25 mm to 5 mm, more preferably from 0.5 mm to 3 mm. By setting it within such a range, the wearing stability and the measurement stability can be enhanced.

[0032] The columnar part 20 has an inclined surface 28 at at least a part of the periphery in the top view. As shown in FIG. 1(b), the inclination angle θ of the inclined surface 28 means the angle formed by the side surface (inclined surface 28) of the base end part 24 of the columnar part 20 and the flat surface 12 in the cross-sectional view passing through the tip 22 of the columnar part 20. The inclination angle θ of the inclined surface 28 is, for example, from 10 to 89 degrees, preferably from 15 degrees to 85 degrees, more preferably from 20 degrees to 75 degrees, and still more preferably from 30 degrees to 65 degrees. By setting it to be equal to or greater than the above lower limit value, the followability to the measurement surface can be enhanced. By setting it to be equal to or less than the above upper limit value, the variation in the deformed state can be suppressed.

[0033] The inclination angle of the inclined surface 29 of the tip part 26 (the angle formed by the inclined surface 29 and the flat surface 12) may be the same as the inclination angle θ of the inclined surface 28 of the base end part 24, but it may also be configured to be slightly smaller than the inclination angle θ. Thereby, it becomes possible to appropriately adjust the inclination angle θ and the angle of the roundness. A corner or a roundness may be formed between the inclined surface 29 of the tip part 26 and the inclined surface 28 of the base end part 24, or it may be configured seamlessly.

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

[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, more preferably 2 to 10. By setting it within such a range, the measurement stability and the manufacturing stability can be enhanced.

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

[0037] As the conductive wire 60, known ones can be used. For example, it can be composed of conductive fibers. As the conductive fibers, 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 can be used. These can be used alone or in combination of two or more.

[0038] The metal materials of the above-mentioned metal fibers and metal-coated fibers are not limited as long as they have conductivity, and examples include copper, silver, gold, nickel, tin, lead, zinc, bismuth, antimony, stainless steel, aluminum, silver / silver chloride, and alloys thereof. These can be used alone or in combination of two or more. Among these, silver can be used from the viewpoint of conductivity. Also, it is preferable that the metal material does not contain metals that impose a load on the environment, such as chromium.

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

[0040] Examples of the above-mentioned carbon fibers include PAN-based carbon fibers and pitch-based carbon fibers.

[0041] The conductive polymer materials of the above-mentioned conductive polymer fibers and conductive polymer-coated fibers are, for example, mixtures of conductive polymers such as polythiophene, polypyrrole, polyaniline, polyacetylene, polyphenylene vinylene, polynaphthalene, and their derivatives, and binder resins, or aqueous solutions of conductive polymers such as PEDOT-PSS ((3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid)) are used.

[0042] The resin material contained in the conductive paste of the above-mentioned conductive paste-coated fiber is not particularly limited, but preferably has elasticity, and can include, 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 can be used alone or in combination of two or more.

[0043] The conductive filler contained in the conductive paste of the above-mentioned conductive paste-coated fiber is not particularly limited, and known conductive materials may be used, but can 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 above-mentioned conductive filler is not particularly limited, and can include, for example, at least one of copper, silver, gold, nickel, tin, lead, zinc, bismuth, antimony, silver / silver chloride, or their alloys, or can include two or more of these. Among these, silver or copper is preferable due to their high conductivity and easy availability.

[0045] The above-mentioned conductive wire 60 may be composed of a twisted yarn obtained by twisting a plurality of linear conductive fibers together. Thereby, disconnection of the conductive wire 60 during deformation can be suppressed.

[0046] In this specification, the coating on the conductive fiber not only simply covers the outer surface of the fiber material, but also in the case of a twisted yarn formed by twisting single fibers, includes those in which the inter-fiber gaps in the twisted yarn are impregnated with metal, conductive polymer, or conductive paste, and each single fiber constituting the twisted yarn is coated one by one.

[0047] The tensile break elongation of the conductive wire 60 is, for example, 1% or more to 50% or less, preferably 1.5% or more to 45%. By setting it within such a numerical range, while suppressing breakage during deformation, excessive deformation of the columnar portion 20 can be suppressed. The conductive wire 60 can adopt various arrangement structures as long as it conducts inside the columnar portion 20. For example, the tip of the conductive wire 60 may have a structure protruding from, being substantially on the same plane as, or buried in relation to the tip 22 of the columnar portion 20 or the inclined surface 29 of the tip portion 26. From the viewpoint of connection stability with the conductive resin layer 30, a protruding structure may be used. The protruding portion at the tip of the conductive wire 60 is partially or entirely covered with the conductive resin layer 30.

[0048] The discharge structure at the tip of the conductive wire 60 can adopt a structure without a fold, with a fold, or wound around the surface of the tip portion 26 of the columnar portion 20. Further, the conductive wire 60 may not pass through the central axis of the columnar portion 20 and 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-like support portion 10. For example, the other end of the conductive wire 60 may pass through the base end portion 24 of the columnar portion 20 and further extend to one surface 12, the side surface, or the other surface 14 side of the plate-like support portion 10. The other end of the conductive wire 60 may be electrically connected to the connector via the 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 portion 20, and may be configured to cover from the tip 22 to the tip portion 26 of the columnar portion 20, or from the tip 22 to the middle of the base end portion 24. That is, it may be configured not to cover the entire surface of the columnar portion 20. This conductive resin layer 30 may be configured to cover one surface 12 or 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 composed of conductive silicone rubber containing a conductive filler and silicone rubber as one of the conductive elastic members. For example, a conductive solution (conductive silicone rubber-based curable composition) obtained by adding a conductive filler to an insulating silicone rubber-based curable composition not containing a conductive filler described later is applied to the above-mentioned molded body, whereby the conductive resin layer 30 can be formed. By using the same type of silicone rubber material as the silicone rubber constituting the plate-shaped support portion 10 and the columnar portion 20, the adhesion of the conductive resin layer 30 can be improved.

[0052] As the above-mentioned conductive filler, a known conductive material may be used, but it can contain 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 above-mentioned conductive filler is not particularly limited. For example, it can contain 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 preferable due to their high conductivity and easy 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, more preferably 40% by mass or more, based on 100% by mass of the silicone rubber in the conductive resin layer 30. Thereby, even in the case of a thin film, the transmission property of the bioelectrical signal can be enhanced. 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, more preferably 80% by mass or less, based on 100% by mass of the silicone rubber in the conductive resin layer 30. Thereby, the durability of the conductive resin layer 30 against the deformation of the columnar portion 20 can be enhanced.

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

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

[0057] In this embodiment, the type A durometer hardness on the surface of the columnar portion 20 (elastic columnar portion), measured in accordance with JIS K 6253 (1997) at 37°C, is defined as rubber hardness A. As the measurement target for rubber hardness A, methods using the columnar portion 20, methods using the plate-shaped support portion 10 when the columnar portion 20 and the plate-shaped support portion 10 are formed as an integral member, and methods using the silicone rubber constituting these can be adopted. Also, when the conductive resin layer 30 has little influence on the rubber hardness A due to being a thin layer, the columnar portion 20 or the plate-shaped support portion 10 with the conductive resin layer 30 formed on the surface may be used as the measurement target. Test pieces can be prepared from these, and the test pieces can be used as the measurement target (sample). A sample thickness may be the superposition of a plurality of test pieces. 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 above rubber hardness A is, for example, 15 or more, preferably 18 or more, and more preferably 20 or more. Thereby, the contact resistance can be lowered and the electroencephalogram acquisition rate can be increased. On the other hand, the upper limit of the above rubber hardness A is 65 or less, preferably 53 or less, and more preferably 50 or less. Thereby, the contact resistance can be lowered. Also, when contacting the measurement portion, the columnar portion 20 can be easily deformed and can be deformed into a state following the shape of the measurement portion, so the wearing feeling of the subject (user) can be enhanced and the discomfort during long-term use can be suppressed.

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

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

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

[0062] The insulating silicone rubber-based curable composition and the conductive silicone rubber-based curable composition may contain the same kind of vinyl group-containing linear organopolysiloxane. The same kind of vinyl group-containing linear organopolysiloxane means that it contains at least the same vinyl functional group and has a linear structure, and the amount of vinyl groups, molecular weight distribution, or the added amount in the molecule may be different. Note that the insulating silicone rubber-based curable composition and the conductive silicone rubber-based curable composition may further contain different vinyl group-containing organopolysiloxanes from each other.

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

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

[0065] The content of vinyl groups in the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited. For example, it preferably has two or more vinyl groups in the molecule and is 15 mol% or less, and more preferably 0.01 to 12 mol%. Thereby, the amount of vinyl groups in the vinyl group-containing linear organopolysiloxane (A1) is optimized, and the formation of a network with each component described below can be surely carried out. In this embodiment, "~" means including the numerical values at both ends thereof.

[0066] In addition, in this specification, the vinyl group content refers to the mole percentage of vinyl group-containing siloxane units when the total units constituting the vinyl group-containing linear organopolysiloxane (A1) are 100 mol%. However, for one vinyl group-containing siloxane unit, it is considered to have one vinyl group.

[0067] Also, the degree of polymerization of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited. For example, it is preferably in the range of about 1000 to 10000, more preferably in the range of about 2000 to 5000. The degree of polymerization can be determined, for example, as the number average degree of polymerization (or number average molecular weight) in terms of polystyrene in GPC (gel permeation chromatography) using chloroform as the 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 the 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] The vinyl group-containing linear organopolysiloxane (A1) preferably has a structure represented by the following formula (1) in particular.

[0071]

Chemical formula

[0072] In formula (1), R 1is a substituted or unsubstituted alkyl group, alkenyl group, aryl group having 1 to 10 carbon atoms, or a hydrocarbon group combining these. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, etc., and among them, the 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., and among them, the vinyl group is preferable. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group, etc.

[0073] Also, R 2 is a substituted or unsubstituted alkyl group, alkenyl group, aryl group having 1 to 10 carbon atoms, or a hydrocarbon group combining these. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, etc., and among them, the 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. 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, aryl group having 1 to 8 carbon atoms, or a hydrocarbon group combining these. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, a propyl group, etc., and among them, the methyl group is preferable. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group.

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

[0076] In addition, in formula (1), a plurality of R 1 are independent of each other, and may be different from each other or the same. Furthermore, the same applies to R 2 , and R 3 as well.

[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 group-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 The first vinyl group-containing linear organopolysiloxane (A1-1) having two or more vinyl group-containing units in the molecule and containing 0.4 mol% or less, and R 1 The unit in which R 2 is a vinyl group and / or R

[0083] It is preferable to use the second vinyl group-containing linear organopolysiloxane (A1-2) containing 0.5 to 15 mol% of the unit in which R

[0084] is a vinyl group. Further, the first vinyl group-containing linear organopolysiloxane (A1-1) preferably has a vinyl group content of 0.01 to 0.2 mol%. Further, the second vinyl group-containing linear organopolysiloxane (A1-2) preferably has a vinyl group content of 0.8 to 12 mol%.

[0085] 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. 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] In addition, only one kind of each of the first and second vinyl group-containing linear organopolysiloxanes (A1-1) and (A1-2) may be used, or two or more kinds may be used in combination.

[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 curable composition of the present embodiment may contain a crosslinking agent. The crosslinking agent can 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 can contain either one or both of them.

[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 only needs to have at least a common structure such as a linear structure or a branched structure, and may contain a molecular weight distribution or different functional groups in the molecule, and the added amounts thereof may be different. In addition, the insulating silicone rubber-based curable composition and the conductive silicone rubber-based curable composition may further contain different crosslinking agents from each other.

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

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

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

[0092] Also, the linear organohydrogenpolysiloxane (B1) preferably does not usually have a vinyl group. Thereby, it is possible to accurately prevent the crosslinking reaction from proceeding in the molecule of the linear organohydrogenpolysiloxane (B1).

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

[0094]

Chemical formula

[0095] In formula (2), R 4 is a substituted or unsubstituted alkyl group, alkenyl group, aryl group, hydrocarbon group combining these, or 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 them, 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, hydrocarbon group combining these, or 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, and among them, 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.

[0097] In addition, in formula (2), a plurality of R 4 are independent of each other, and may be different from each other or the same. The same applies to R 5 . However, among a plurality of R 4 and R 5 , at least two or more are hydride groups.

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

[0099] In addition, as for the substituents of R 4 , R 5 , R 6 in the formula (2), examples include a methyl group, a vinyl group, etc., and from the viewpoint of preventing an intramolecular crosslinking reaction, a methyl group is preferable.

[0100] Furthermore, m and n are the number of repeating units constituting the linear organohydrogenpolysiloxane (B1) represented by the formula (2), 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] In addition, as for the linear organohydrogenpolysiloxane (B1), only one kind may be used alone, or two or more kinds may be used in combination.

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

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

[0104] Furthermore, the branched organohydrogenpolysiloxane (B2) preferably does not usually have a vinyl group. Thereby, it is possible to accurately prevent the crosslinking reaction from proceeding within the molecule of the branched organohydrogenpolysiloxane (B2).

[0105] Moreover, as the branched organohydrogenpolysiloxane (B2), those represented by the following average composition formula (c) are preferable.

[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 in the range of 1 to 3, m is the number of H a (R 7 ) 3-a SiO 1 / 2 units, and n is the number of SiO 4 / 2 units)

[0107] In formula (c), R 7 is a monovalent organic group, preferably a substituted or unsubstituted alkyl group, aryl group, or a hydrocarbon group combining these, 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 them, a methyl group is preferable. 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), an integer in the range of 1 to 3, preferably 1.

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

[0110] The branched organohydrogenpolysiloxane (B2) has a branched structure. The linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2) differ in that the former has a linear structure while the latter has a branched structure, and the number of alkyl groups R bonded to Si (R / Si) when the number of Si is taken as 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] In addition, since the branched organohydrogenpolysiloxane (B2) has a branched structure, for example, when heated at a rate of 10 °C / min up to 1000 °C in a nitrogen atmosphere, the residue amount becomes 5% or more. On the other hand, since the linear organohydrogenpolysiloxane (B1) is linear, the residue amount after heating under the above conditions is almost zero.

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

[0113]

Chemical formula

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

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

[0116] In addition, in Formula (3), “-O-Si≡” represents that Si has a branched structure extending three-dimensionally.

[0117] Note that the branched organohydrogenpolysiloxane (B2) may be used alone as a single type, or in combination of two or more types.

[0118] In addition, in the linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2), the amount of hydrogen atoms (hydride groups) directly bonded to Si 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, and more preferably 1 to 3.5 moles, per 1 mole of vinyl groups in the vinyl group-containing linear organopolysiloxane (A1). Thereby, a crosslinked network can be surely 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 curable composition according to this embodiment contains a non-conductive filler. The non-conductive filler may contain silica particles (C) as necessary. Thereby, the hardness and mechanical strength of the elastomer can be improved.

[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 same type of non-conductive filler only needs to have at least a common constituent material, and the particle diameter, specific surface area, surface treatment agent, or the addition amount thereof may be different. Note that 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, and for example, fumed silica, calcined silica, precipitated silica, etc. are used. These may be used alone or in combination of two or more.

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

[0123] By using the silica particles (C) within the ranges of such specific surface area and average particle diameter, it is possible to improve the hardness and mechanical strength of the formed silicone rubber, particularly the tensile strength.

[0124] <<Silane coupling agent (D)>> The silicone rubber-based curable composition of the present embodiment can contain a silane coupling agent (D). The silane coupling agent (D) can have a hydrolyzable group. The hydrolyzable group is hydrolyzed by water to become a hydroxyl group, and this hydroxyl group can react with the hydroxyl group on the surface of the silica particles (C) by dehydration condensation reaction to perform surface modification 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 only needs to have at least a common functional group, and the other functional groups and the addition amount in the molecule may be different. Note that the insulating silicone rubber-based curable composition and the conductive silicone rubber-based curable composition may further contain different silane coupling agents from each other.

[0126] Further, this silane coupling agent (D) can include a silane coupling agent having a hydrophobic group. As a result, since this hydrophobic group is imparted to the surface of the silica particles (C), the cohesive force of the silica particles (C) decreases (the aggregation due to hydrogen bonding by silanol groups decreases) in the silicone rubber-based curable composition and thus in the silicone rubber. As a result, it is presumed that the dispersibility of the silica particles (C) in the silicone rubber-based curable composition is improved. Thereby, the interface between the silica particles (C) and the rubber matrix increases, and the reinforcing effect of the silica particles (C) increases. Further, when the matrix of the rubber is deformed, it is presumed that the slipperiness of the silica particles (C) within the matrix is improved. And due to the improvement of the dispersibility and the slipperiness of the silica particles (C), the mechanical strength of the silicone rubber by the silica particles (C) (for example, tensile strength, tear strength, etc.) is improved.

[0127] Furthermore, the silane coupling agent (D) can include a silane coupling agent having a vinyl group. Thereby, a vinyl group is 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) thereby, 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. Thereby, it is possible to achieve a decrease in the hardness and an increase in the modulus of the formed silicone rubber.

[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] Examples of the silane coupling agent (D) include those represented by the following formula (4).

[0130] Yn -Si-(X) 4-n ···(4) In the above formula (4), n represents an integer from 1 to 3. Y represents any functional group among those having a hydrophobic group, a hydrophilic group, or a vinyl group. 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 combining these, and examples thereof include a methyl group, an ethyl group, a propyl group, a phenyl group, etc. Among them, particularly, a methyl group is preferable.

[0132] Also, examples of the hydrophilic group include a hydroxyl group, a sulfonic acid group, a carboxyl group, or a carbonyl group, etc. Among them, particularly, a hydroxyl group is preferable. Note that the hydrophilic group may be included as a functional group, but from the viewpoint of imparting hydrophobicity to the silane coupling agent (D), it is preferably not included.

[0133] Furthermore, examples of the hydrolyzable group include an alkoxy group such as a methoxy group or an ethoxy group, a chloro group, or a silazane group, etc. Among them, since the reactivity with the silica particles (C) is high, a silazane group is preferable. Note that those having a silazane group as the hydrolyzable group will have two (-Si-) structures in the above formula (4) due to the structural characteristics. n -Si-) structures.

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

[0135] As those having a vinyl group as the functional group, for example, alkoxysilanes such as methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane; chlorosilanes such as vinyltrichlorosilane, vinylmethyldichlorosilane; divinyldimethyltetrasilazane can be mentioned. Among these, a silane coupling agent having a vinyl group-containing organosilyl group containing one or more selected from the group consisting of methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, divinyldimethyltetrasilazane, vinyltriethoxysilane, vinyltrimethoxysilane, and vinylmethyldimethoxysilane is preferable.

[0136] When the silane coupling agent (D) contains two types, namely a silane coupling agent having a trimethylsilyl group and a silane coupling agent having a vinyl group-containing organosilyl group, it preferably contains hexamethyldisilazane as the one having a hydrophobic group and divinyltetramethyldisilazane as the one having a vinyl group.

[0137] When using a silane coupling agent (D1) having a trimethylsilyl group and a silane coupling agent (D2) having a vinyl group-containing organosilyl group in combination, the ratio of (D1) to (D2) is not particularly limited. For example, in terms of weight ratio, (D1):(D2) is 1:0.001 to 1:0.35, preferably 1:0.01 to 1:0.20, and more preferably 1:0.03 to 1:0.15. By setting such a numerical range, the desired physical properties of the silicone rubber can be obtained. Specifically, the balance between the dispersibility of silica in the rubber and the crosslinkability of the rubber can be achieved.

[0138] In this embodiment, the lower limit value 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 with respect to 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A). Also, the upper limit value 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 with respect to 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A). By setting the content of the silane coupling agent (D) to be not less than the above lower limit value, the adhesion between the columnar part containing the elastomer and the conductive resin layer can be enhanced. Also, it can contribute to the improvement of the mechanical strength of the silicone rubber. Further, by setting the content of the silane coupling agent (D) to be not more than the above upper limit value, the silicone rubber can have appropriate mechanical properties.

[0139] <<Platinum or platinum compound (E)>> The silicone rubber-based curable composition according to this embodiment may contain a catalyst. The catalyst can contain platinum or a platinum compound (E). Platinum or the platinum compound (E) is a catalyst component that acts as a catalyst during curing. The addition amount of platinum or the platinum compound (E) is the catalyst 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 only needs to have at least a common constituent material, and different compositions may be included in the catalyst, and their addition amounts may also be different. In addition, the insulating silicone rubber-based curable composition and the conductive silicone rubber-based curable composition may further contain different catalysts from each other.

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

[0142] In addition, only one kind of platinum or the platinum compound (E) may be used alone, or two or more kinds may be used in combination.

[0143] In this embodiment, the content of platinum or the platinum compound (E) in the silicone rubber-based curable composition means the catalyst amount and can be set as appropriate. Specifically, based on 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A), silica particles (C), and silane coupling agent (D), the amount of the platinum group metal is 0.01 to 1000 ppm in weight units, and preferably, the amount is 0.1 to 500 ppm. By setting the content of platinum or the platinum compound (E) to be not less than the above lower limit value, the silicone rubber-based curable composition can be cured at an appropriate rate. Also, by setting the content of platinum or the platinum compound (E) to be not more than the above upper limit value, it is possible to contribute to the reduction of manufacturing costs.

[0144] <<Water (F)>> In addition, the silicone rubber-based curable 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 curable composition and is a component that contributes to the reaction between the silica particles (C) and the silane coupling agent (D). Therefore, in the silicone rubber, the silica particles (C) and the silane coupling agent (D) can be more reliably connected to each other, and uniform properties can be exhibited as a whole.

[0146] (Other components) Furthermore, the silicone rubber-based curable composition of this embodiment can further contain other components in addition to the above components (A) to (F). Examples of such other components include 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, mica, reaction inhibitors, dispersants, pigments, dyes, antistatic agents, antioxidants, flame retardants, heat conductivity improvers, and other additives.

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

[0148] As the above solvent, various known solvents can be used. For example, a high-boiling solvent can be included. These may be used alone or in combination of two or more.

[0149] Examples of the above solvents 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 can be used alone or in combination of two or more.

[0150] By adjusting the solid content in the solution and the like, the above conductive solution can have an appropriate viscosity for various coating methods such as spray coating and dip coating.

[0151] When the above conductive solution contains the above conductive filler and the above 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% by mass or more, preferably 3% by mass or more, more preferably 5% by mass or more, based on 100% by mass of the total amount of the silica particles (C) and the conductive filler. Thereby, the mechanical strength of the conductive resin layer 30 can be improved. On the other hand, the upper limit of the content of the silica particles (C) contained in the conductive resin layer 30 can be, for example, 20% by mass or less, preferably 15% by mass or less, more preferably 10% by mass or less, based on 100% by mass of the total amount of the silica particles (C) and the conductive filler. Thereby, the balance between the conductivity and the mechanical strength and flexibility in the conductive resin layer 30 can be achieved.

[0152] By heating and drying the conductive solution as needed, a conductive silicone rubber can be obtained. The conductive silicone rubber may be configured not to contain silicone oil. This can suppress a decrease in conductivity due to silicone oil bleeding out on the surface of the conductive resin layer 30.

[0153] An example of the method for manufacturing the biological electrode 100 of the present embodiment can include the following steps. First, using a mold, the silicone rubber-based curable composition is heated and pressure-molded to obtain a molded body having a plate-shaped support portion 10 and a columnar portion 20 (molding step).

[0154] Subsequently, a conductive wire 60 is inserted into the columnar portion 20 of the obtained molded body (conductive wire insertion step). For example, the conductive wire 60 can be passed through the columnar portion 20 using a needle. Note that mass production is possible by using a sewing machine. Alternatively, at the time of the above molding step, insert molding may be used in which the silicone rubber-based curable composition is introduced into the molding space in which the conductive wire 60 is arranged, and pressure-heat molding is performed.

[0155] Subsequently, the tip portion 26 of the columnar portion 20 of the obtained molded body is dip-coated with the conductive solution and heated and dried (tip coating step). The conductive solution may be spray-coated on the tip portion 26 and heated and dried. Thereby, a conductive resin layer 30 covering the tip 22 of the columnar portion 20 is formed. Thereafter, post-curing (annealing step) is performed under predetermined temperature and temperature conditions. As described above, the biological electrode 100 can be manufactured.

[0156] As an example of other manufacturing methods, the following steps may be included. In the molding step, for example, using a mold having a plurality of recesses, a molded body sheet in which a set of a plurality of columnar portions 20 and a plate-shaped support portion 10 is formed is obtained. Subsequently, in the conductive wire insertion step, the conductive wire 60 is inserted into the plurality of columnar portions 20 in the molded body sheet. Subsequently, in the tip coating step, a conductive resin layer 30 that covers at least the tip 22 is formed at the tip portions 26 of the plurality of columnar portions 20 in the formed body sheet. Subsequently, an individualized formed body including the plate-like support portion 10, the columnar portion 20, the conductive wire 60, and the conductive resin layer 30 is taken out from the formed body sheet (individualization step). As a method for taking out, for example, a method of punching out the formed body sheet may be employed. Thereafter, in the annealing step, each individualized formed body is post-cured. Thus, the biological electrode 100 can be manufactured.

[0157] Note that after the above-mentioned forming step and before the above-mentioned conductive wire insertion step, the tip portion 26 of the columnar portion 20 may be cut (trimmed) into a desired shape to form an inclined surface. Alternatively, instead of cutting, an inclined surface may be formed on the tip portion 26 of the columnar portion 20 by die forming.

[0158] The biological electrode 100 of the present embodiment can detect bioelectric signals generated from biological activities such as the brain, heart, muscles, and nerves. Since this biological electrode 100 has flexibility, it has excellent wearability on the scalp and can be suitably used as an electrode for electroencephalogram measurement.

[0159] The electroencephalogram measurement electrode using the biological electrode 100 is expected to be utilized for BMI (Brain Machine Interface).

[0160] In addition, the biological electrode 100 is not a wet sensor that requires application of gel to the measurement part, and can be used as a simple and reusable dry sensor. Further, the biological electrode 100 can have flexibility that can reduce pain and discomfort of the subject (user) as compared with a dry sensor of a metal pin type with a spring. Further, the biological electrode 100 can be mounted on a wearable device by miniaturization.

[0161] The biological sensor of the present embodiment will be described. FIG. 2 is a schematic diagram showing an outline of an example of the biological sensor 200. The biosensor 200 of this embodiment includes a living body electrode 100, and may further include an external connection part 110 connected to the living body electrode 100.

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

[0163] The external connection part 110 is stronger than silicone rubber from the viewpoint of durability and includes at least an external electrode part having conductivity. The external electrode part is made of, for example, metal. This external electrode part can send the bioelectric signal detected by the living body electrode 100 to external electronic components. The shape of the external electrode part is not particularly limited, but is configured to be connectable to an electronic component or to which wiring can be attached. For example, the external connection part 110 may be composed of a metal snap button and have a structure in which it is electrically connected to an external wiring or an electrode of a substrate by a contact pin.

[0164] The biosensor 200 may further include an electronic component that can be electrically connected via the external connection part 110. As the electronic component, known components can be used according to various applications. For example, an amplifier, an AD converter, a CPU, a memory, a communication circuit, a wireless communication unit, an analog filter, a capacitor, a resistor, a battery, etc. can be mentioned. One or two or more of these may be modularized on a circuit board. Thereby, the biosensor 200 can be utilized as a wearable device. Also, as the electronic component, other sensors such as an acceleration sensor, a temperature sensor, and a pressure sensor may be used in combination.

[0165] The biosensor 200 includes one or a plurality of two or more living body electrodes 100. The biosensor 200 may be installed in a fixture for attaching to a living body such as a headgear or an armband.

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

[0167] As described above, the embodiments of the present invention have been described, but these are examples of the present invention, and various configurations other than the above can be adopted. Further, the present invention is not limited to the above-described embodiments, and modifications, improvements, etc. within the scope capable of achieving the object of the present invention are included in the present invention.

Example

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

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

[0170] (Vinyl group-containing organopolysiloxane (A)) (A1-1): The first vinyl group-containing linear organopolysiloxane: vinyl group content is 0.04 mol%, Mn = 2.2×10 5 , Mw = 4.8×10 5 ), vinyl group-containing dimethylpolysiloxane synthesized by the following synthesis scheme 1 (structure represented by the above formula (1-1)) (A1-2): The second vinyl group-containing linear organopolysiloxane: vinyl group content is 0.93 mol%, vinyl group-containing dimethylpolysiloxane synthesized by the following synthesis scheme 2 (structure represented by the above formula (1-1) where R 1 and R 2 are vinyl groups)

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

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

[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 compound (E)) (E): Platinum or platinum compound: manufactured by Momentive, "TC-25A"

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

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

[0177] (Synthesis of vinyl group-containing organopolysiloxane (A)) [Synthesis scheme 1: Synthesis of the first vinyl group-containing linear organopolysiloxane (A1-1)] According to the following formula (5), the first vinyl group-containing linear organopolysiloxane (A1-1) was synthesized. That is, 74.7 g (252 mmol) of octamethylcyclotetrasiloxane and 0.1 g of potassium silicate were placed in a 300 mL separable flask equipped with a cooling tube and a stirring blade, purged with Ar gas, heated, and stirred at 120 °C for 30 minutes. At this time, an increase in viscosity was confirmed. Subsequently, the temperature was raised to 155 °C and stirring was continued for 3 hours. Then, after 3 hours, 0.1 g (0.6 mmol) of 1,3-divinyltetramethyldisiloxane was added, and stirring was further carried out at 155 °C for 4 hours. Furthermore, after 4 hours, it was diluted with 250 mL of toluene and then washed three times with water. The washed organic layer was reprecipitated and purified by washing several times with 1.5 L of methanol to separate the oligomer and the polymer. The obtained polymer was dried under reduced pressure at 60 °C overnight to obtain the first vinyl group-containing linear organopolysiloxane (A1-1) (Mn = 2.2×10 5 , Mw = 4.8×10 5 ). Also, the vinyl group content calculated by 1H-NMR spectrum measurement was 0.04 mol%.

[0178] [Chemical formula]

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

[0180] [Chemical formula]

[0181] [Preparation of silicone rubber-based curable composition] A silicone rubber-based curable composition was prepared as follows. First, a mixture of 90% vinyl group-containing organopolysiloxane (A), silane coupling agent (D), and water (F) was kneaded in advance at the ratios shown in Table 1 below. Then, silica particles (C) were added to the mixture and further kneaded to obtain a kneaded product (silicone rubber compound). Here, the kneading after adding the silica particles (C) was carried out through a first step of kneading for 1 hour under the conditions of 60 - 90 °C in a nitrogen atmosphere for the coupling reaction, and a second step of kneading for 2 hours under the conditions of 160 - 180 °C in a reduced-pressure atmosphere for removing by-products (ammonia). Then, it was cooled, and the remaining 10% vinyl group-containing organopolysiloxane (A) was added in two portions and kneaded for 20 minutes. Subsequently, organohydrogenpolysiloxane (B) and platinum or a platinum compound (E) were added to 100 parts by weight of the obtained kneaded product (silicone rubber compound) at the ratios shown in Table 1 below, and 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> 13.7 parts by weight of the obtained silicone rubber-based curable composition A was immersed in 31.8 parts by weight of decane (solvent), then stirred with a planetary mixer, and after adding 54.5 parts by weight of metal powder (G1), it was kneaded with a three-roll mill to obtain a conductive paste (conductive solution for dip coating).

[0184] <Preparation of Conductive Solution for Spray Coating> 13.7 parts by weight of the obtained silicone rubber-based curable composition A was immersed in 31.8 parts by weight of decane (solvent), then stirred with a planetary mixer, and after adding 54.5 parts by weight of metal powder (G1), it was kneaded with a three-roll mill to obtain a resin varnish. Then, the resin varnish was added 2.5 times with decane and stirred and diluted with a planetary mixer to obtain a conductive solution for spray coating.

[0185] <Fabrication of Bioprobe (Example 1) Using the silicone rubber-based curable composition A obtained above, a mold having a plurality of molding spaces (recesses) for a plate-shaped support portion and a substantially conical columnar portion was used to heat at 180 °C and 10 MPa for 10 minutes to cure, and in each recess, a molded body in which the plate-shaped support portion and the columnar portion were integrated was obtained (molding step). Using a sewing needle, conductive wire A (manufactured by Mitsufuji Co., Ltd., AGposs, thickness: 100d / 34f, tensile elongation at break: 29.3%) was passed through the inside of the columnar portion of the obtained molded body (conductive wire insertion step). Subsequently, the tip portion of the columnar portion of the molded body (region approximately 1 / 2L from the tip when the total length of the columnar portion is L) and the other surface of the plate-shaped support portion were dipped in the above <conductive solution for dip coating> and heated and dried at 120 °C for 30 minutes (tip coating step). Thereafter, post-curing was performed at 140 °C for 2 hours (annealing step). As described above, a bioprobe A having a substantially conical columnar portion 20 on a plate-shaped support portion 10 shown in FIG. 1 was obtained. In the bioprobe 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 from the tip 22 of the columnar portion 20, and it was covered with the conductive resin layer 30.

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

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

[0188] (Comparative Example 1) In the same manner as in Example 1, a molded body of the above <fabrication of bioprobe> was obtained. Without performing the conductive wire insertion step, the above <conductive solution for spray coating> was spray-coated on the entire surface of the obtained molded body and dried by heating at 120 °C for 30 minutes to form a conductive resin layer on the entire surface of the molded body. Thereafter, post-curing was performed at 140 °C for 2 hours to obtain the biological electrode D.

[0189] Regarding the obtained biological electrodes A to D, evaluations were performed on the following evaluation items. The evaluation results are shown in Table 2.

[0190] (Wearing stability) In the same manner as in Example 1, the above <fabrication of biological electrode> was performed, and a 2 mmφ steel ball (high-carbon chromium bearing steel material manufactured by Tsubaki Nakashima Co., Ltd.) was attached to the tip so as to be connected to the conductive wire, and the biological electrode E of Comparative Example 2 was obtained.

[0191] While pressing the tip of the columnar portion of the biological electrode E of Comparative Example 2 against the posterior head of the subject, the measuring element of a push-pull gauge (manufactured by Nidec-Shimpo Corporation, product name: Digital Force Gauge FGJN-2) was pressed against the other surface of the biological electrode E on the side opposite to the tip with a constant load of 15 N. As a result, in the subject, it was evaluated that pain was felt and it could only be tolerated for a short time.

[0192] On the other hand, when the biological electrodes A to C of Examples 1 to 3 were used, it was evaluated that there was a feeling of contact but it was not bothersome, or no pain was felt. Therefore, it was found that the biological electrodes A to C of Examples 1 to 3 are superior in wearing stability compared to the biological electrode E of Comparative Example 2.

[0193]

Table 2

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

[0195] Subsequently, a headgear for electroencephalogram measurement (a headgear with node arrangement based on the international 10 / 20 method, molded by a 3D printer) was worn on the head of the subject. Thereafter, the tip 26 of the biological electrode 100 was brought into contact with the back of the subject's head, and while pressing the tip 26 of the columnar part 20 of the obtained biological electrode 100 against the back of the subject's head (0z), the measuring element of a push-pull gauge (product name: Digital Force Gauge FGJN-2, manufactured by Nidec-Shimpo Corporation) was first pressed against the external connection part 110 of the biological electrode 100 with a load of 7N, and then gradually unloaded, and the contact resistance (kΩ) at 5N, 3N, and 1N was continuously measured to evaluate the change in contact resistance with respect to the load. The results are shown in Table 2.

[0196] Based on Table 2, it was found that the biological electrode of Example 1 had a smaller change amount of 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 wearing stability compared to the biological electrode E of Comparative Example 2 and superior in measurement stability compared to the biological electrode D of Comparative Example 1.

Explanation of reference numerals

[0198] 10 Plate-shaped support part 12 One surface 14 The other surface 20 Columnar part 22 Tip 24 Base end part 26 Tip part 28 Inclined surface 29 Inclined surface 30 Conductive resin layer 60 Conductive wire 100 Biocompatible electrode 110 External connection part 200 Biosensor

Claims

1. An insulating plate-shaped support portion, a substantially conical insulating elastic columnar portion provided on one surface of the insulating plate-shaped support portion, a conductive resin layer formed so as to cover the tip of the insulating elastic columnar portion, a conductive wire that is electrically connected to the conductive resin layer and is disposed inside the insulating elastic columnar portion and the insulating plate-shaped support portion from the tip side toward the base end side, comprising, a biological electrode used for measuring potential fluctuations from a living body.

2. The biological electrode according to claim 1, wherein the tip portion of the insulating elastic columnar portion is constituted by any one of a substantially hemispherical shape, an ellipsoidal shape, a conical shape, a frustum of a cone shape, a pyramid shape, or a substantially pyramid shape.

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

4. The biological electrode according to any one of claims 1 to 3, wherein the insulating plate-shaped support portion and the insulating elastic columnar portion are constituted by an integral member.

5. The biological electrode according to any one of claims 1 to 4, wherein the conductive wire is constituted by conductive fibers.

6. The biological electrode according to any one of claims 1 to 5, wherein the conductive wire is constituted by a twisted yarn obtained by twisting a plurality of linear conductive fibers.

7. The biological electrode according to claim 6, wherein the conductive fibers include 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. The biological electrode according to any one of claims 1 to 7, wherein the insulating elastic columnar portion is constituted by an insulating silicone rubber containing silicone rubber.

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

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

11. The biological electrode according to claim 9 or 10, The biocompatible electrode, wherein the conductive filler includes 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. The biocompatible electrode according to any one of Claims 1 to 11, which is used as an electrode for electroencephalogram measurement.

13. A biosensor comprising the biocompatible electrode according to any one of Claims 1 to 12.

14. A biological signal measurement system comprising the biosensor according to Claim 13.

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