Double-sided conductive sheet

Abstract

To provide a double-sided conductive sheet having excellent conductive properties during sheet deformation.SOLUTION: The double-sided conductive sheet of the present invention comprises a structure in which a lower layer composed of conductive elastomer A, a middle layer sheet composed of insulating elastomer, and an upper layer composed of conductive elastomer B are laminated in this order, and comprises at least one or more conductive portions composed of conductive elastomer C, which penetrate the middle layer sheet and conduct the lower layer and the upper layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a double-sided conductive sheet. [Background technology]

[0002] Various developments have been made so far regarding laminate sheets having conductive layers on both sides. One known example of this type of technology is described in Patent Document 1. Patent Document 1 describes a connector for connecting solar cells, which is characterized in that a through-hole is formed in a strip-shaped laminate sheet made of a plastic film with metal foil laminated on each side thereof, and at least the wall surface of the through-hole is made conductive to provide electrical continuity between the two metal foils. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-287378 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as a result of investigations by the present inventors, it has been found that there is room for improvement in the laminate sheet as described in Patent Document 1 above, in terms of the deterioration of the conductive properties when the sheet is deformed. [Means for solving the problem]

[0005] After further investigation, the inventors discovered that by constructing the lower and upper layers formed on both sides of the middle layer sheet made of insulating elastomer, and the conductive portions formed inside the middle sheet, all from conductive elastomer, it is possible to prevent the conductive properties of the double-sided conductive sheet from deteriorating during deformation such as stretching, and thus completed the present invention.

[0006] According to one aspect of the present invention, there is provided the following double-sided conductive sheet. 1. A lower layer made of conductive elastomer A; a middle layer sheet made of an insulating elastomer; and an upper layer made of conductive elastomer B. A double-sided conductive sheet having a structure in which these are laminated in this order, At least one conductive part made of a conductive elastomer C is provided, which penetrates the middle layer sheet and electrically connects the lower layer and the upper layer. Double-sided conductive sheet. 2. The double-sided conductive sheet according to 1., When the breaking elongations of the lower layer, the intermediate sheet, and the upper layer are BE1, BE2, and BE3, and the tensile strengths are TS1, TS2, and TS3, respectively, A double-sided conductive sheet that satisfies BE2>BE1 and BE2>BE3, and / or TS2>TS1 and TS2>TS3. 3. The double-sided conductive sheet according to 2., At least one of BE2 / BE1 and BE2 / BE3 is between 0.1 and 30, and / or A double-sided conductive sheet in which at least one of TS2 / TS1 and TS2 / TS3 satisfies 0.1 or more and 20 or less. 4. The double-sided conductive sheet according to 1., When the thicknesses of the lower layer, the intermediate sheet, and the upper layer in the stacking direction of the double-sided conductive sheet are T1, T2, and T3, respectively, A double-sided conductive sheet that satisfies T2≧T1 and T2≧T3. 5. The double-sided conductive sheet according to 4., A double-sided conductive sheet in which at least one of T2 / T1 and T2 / T3 satisfies 1 or more and 100 or less. 6. A double-sided conductive sheet according to any one of 1. to 5., The thickness of the intermediate sheet is 10 μm or more and 5000 μm or less, and the double-sided conductive sheet. 7. A double-sided conductive sheet according to any one of 1. to 6., The maximum width of the conductive portion is 0.1 mm or more and 15 mm or less, and the double-sided conductive sheet. 8. A double-sided conductive sheet according to any one of 1. to 7., At least one of BE2 / BE1 and BE2 / BE3 is between 0.1 and 30, and / or A double-sided conductive sheet in which at least one of TS2 / TS1 and TS2 / TS3 satisfies 0.1 or more and 20 or less. 9. The double-sided conductive sheet according to any one of 1. to 8., A double-sided conductive sheet used for bioelectrodes. 10. The double-sided conductive sheet according to any one of 1. to 9., A double-sided conductive sheet, wherein at least one of the conductive elastomers A, B, and C comprises a conductive silicone rubber containing a conductive filler. 11. The double-sided conductive sheet according to 10., A double-sided conductive sheet, wherein the content of the conductive filler in at least one of the lower layer, the upper layer, and the conductive portion is 50% by mass or more and 90% by mass or less. 12. A double-sided conductive sheet according to any one of 1. to 11., A double-sided conductive sheet, wherein the insulating elastomer comprises insulating silicone rubber. 13. A double-sided conductive sheet according to any one of 1. to 12., A double-sided conductive sheet, wherein the upper layer and the lower layer are each a conductive sheet or a wiring. [Effects of the Invention]

[0007] According to the present invention, a double-sided conductive sheet is provided that has excellent conductive properties when the sheet is deformed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of the configuration of a double-sided conductive sheet according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are designated by similar reference numerals, and descriptions thereof will be omitted as appropriate. Furthermore, the drawings are schematic diagrams and do not correspond to actual dimensional proportions.

[0010] An overview of the double-sided conductive sheet of this embodiment will be described.

[0011] The double-sided conductive sheet of this embodiment is The device has a structure in which a lower layer made of a conductive elastomer A, a middle layer sheet made of an insulating elastomer, and an upper layer made of a conductive elastomer B are laminated in this order, The sheet has at least one conductive portion made of a conductive elastomer C that penetrates the middle layer sheet and provides electrical continuity between the lower layer and the upper layer.

[0012] The inventors considered using a conductive sheet formed into a sheet using a conductive paste on its own, but found that it had low strength and could break when deformed by bending or stretching, resulting in a risk of reduced conductive properties. Based on this knowledge, we conducted extensive research and found that by using an insulating elastomer sheet material as the core material of the double-sided conductive sheet, the overall strength of the conductive sandwich structure can be improved and the deterioration of conductive properties during such deformation can be suppressed. In addition, the conductive part that electrically connects the upper and lower layers is made of a conductive elastomer, but because it is placed inside the middle layer sheet that is made of an insulating elastomer, it is possible to suppress a decrease in conductive properties during deformation. The detailed mechanism is unclear, but (i) When the double-sided conductive sheet is deformed, the upper and lower layers are reinforced by the relatively flexible middle layer, which prevents breakage and other damage. (ii) When the double-sided conductive sheet is deformed, the stress acting on the middle layer is dispersed to the relatively flexible insulating elastomer layer, reducing the stress load on the conductive part and suppressing breakage, etc. It is presumed that this can prevent the deterioration of the conductive properties of the entire double-sided conductive sheet.

[0013] In addition, in the double-sided conductive sheet according to the first modification, when the breaking elongations of the lower layer, intermediate sheet, and upper layer are BE1, BE2, and BE3, and the tensile strengths are TS1, TS2, and TS3, respectively, The conditions BE2>BE1 and BE2>BE3, and / or TS2>TS1 and TS2>TS3 are satisfied.

[0014] Further investigation by the inventors has revealed that by using an intermediate sheet having high elongation and / or high tensile strength, the overall strength of the conductive sandwich structure during deformation can be increased, thereby further improving the durability of the double-sided conductive sheet.

[0015] Moreover, the double-sided conductive sheet according to the second modification is When the thicknesses of the lower layer, middle sheet, and upper layer in the lamination direction of the double-sided conductive sheet are T1, T2, and T3, respectively, T2≧T1 and T2≧T3 are satisfied.

[0016] Further investigation by the inventors has revealed that the conductive properties of the double-sided conductive sheet during use can be further improved by designing the thickness of the intermediate sheet to be greater than the thickness of the lower or upper layer. Although the detailed mechanism is unclear, it is thought that the use of a thick intermediate sheet can prevent wrinkles from forming in the coating when the conductive paste is applied during the manufacturing process, improving the surface condition of the upper and / or lower conductive layers.

[0017] The double-sided conductive sheet of this embodiment can be used for various purposes, for example, as a bioelectrode.

[0018] The components of the double-sided conductive sheet of this embodiment will be described in detail below.

[0019] FIG. 1 is a cross-sectional view showing a schematic example of the configuration of a double-sided conductive sheet. The double-sided conductive sheet 100 of Figure 1 comprises an intermediate sheet 20, a lower layer 10 formed on the lower surface of the intermediate sheet 20, an upper layer 30 formed on the upper surface of the intermediate sheet 20, and a conductive portion 50 that penetrates the intermediate sheet 20 and electrically connects the lower layer 10 and the intermediate sheet 20.

[0020] First, an example of a method for manufacturing the double-sided conductive sheet 100 will be described. An example of a manufacturing method includes the steps of forming an intermediate sheet 20 of insulating elastomer, forming one or more through holes in the intermediate sheet 20, and using a conductive paste on each of the lower and upper surfaces of the intermediate sheet to form conductive members such as a lower layer 10, an upper layer 30, and a conductive portion 50. Each step may be independent of the other, but the steps may overlap with each other or may be performed simultaneously.

[0021] The intermediate sheet 20 may be formed by a general molding method such as calendar molding or compression molding using an elastomer composition that does not contain a conductive filler, or by a printing method using an insulating paste that contains such a filler.

[0022] The elastomer composition is a composition containing an elastomer or a component for forming an elastomer, and is preferably a thermosetting elastomer composition in an uncured state, more preferably a silicone rubber-based curable composition described below.

[0023] The through holes can be formed by a method using a mold, a cutting method, or, in the case of an insulating paste, a method using a mask with openings.

[0024] The conductive member can be formed by a printing method using a conductive paste containing a conductive filler and the above-described elastomer composition, but is not limited to this method.

[0025] In a specific example of forming the conductive member, a first conductive paste is applied to one side of an intermediate sheet 20 having one or more through holes and dried. Subsequently, a second conductive paste is applied to the other side of the intermediate sheet 20 and dried, and then the coatings on both sides are cured to form the lower layer 10 and the upper layer 30. At this time, the through holes are filled with the first conductive paste and / or the second conductive paste, and the conductive portions 50 can be formed by subsequent curing. The coating films corresponding to the lower layer 10 and the upper layer 30 may each be in the form of a sheet or a pattern. Drying conditions can be set appropriately depending on the type and amount of solvent in the conductive paste, but for example, the drying temperature can be set to 120° C. to 180° C., and the drying time can be set to 1 minute to 30 minutes. Subsequently, the wiring pattern is cured to form the stretchable wiring. The curing conditions can be set appropriately depending on the elastomer composition in the conductive paste and its content. When the elastomer composition is a silicone rubber-based curable composition, for example, the curing temperature is 120°C to 220°C, and the curing time is 1 hour to 3 hours.

[0026] The lower layer 10 and the intermediate sheet 20, and / or the upper layer 30 and the intermediate sheet 20 may be fixed to each other by known fixing methods such as adhesives or adhesive sheet techniques, but it is preferable that they be fixed by having the solvent contained in the above-mentioned conductive paste soak into a portion of the intermediate sheet 20, thereby fusing the lower layer 10 and / or the upper layer 30 to the intermediate sheet 20.

[0027] If necessary, a mask having a predetermined opening pattern may be placed on at least a portion of the surface of the lower layer 10 and the upper layer 30, and an insulating paste may be applied through the mask to form an insulating layer (stretchable cover portion).

[0028] Next, the materials and characteristics of each component of the double-sided conductive sheet 100 will be described.

[0029] At least one of BE2 / BE1 and BE2 / BE3 has a value of, for example, 0.1 to 30, preferably 0.3 to 25, and more preferably 0.5 to 20. By making it equal to or greater than the lower limit, flexibility can be improved. By making it equal to or less than the upper limit, interfacial adhesion can be improved. In this specification, unless otherwise specified, the symbol "to" indicates that the upper and lower limits are included.

[0030] At least one of TS2 / TS1 and TS2 / TS3 is, for example, 0.1 to 20, preferably 0.5 to 15, and more preferably 1 to 10. By making it equal to or greater than the lower limit, durability can be improved. By making it equal to or less than the upper limit, durability of the conductive part can be improved.

[0031] At least one of T2 / T1 and T2 / T3 is, for example, 0.01 to 1500, preferably 0.02 to 1000, and more preferably 0.03 to 500. By setting it to the lower limit or more, durability can be improved. By setting it to the upper limit or less, flexibility can be improved.

[0032] The thickness of the intermediate sheet 20 is, for example, 10 μm to 5000 μm, preferably 50 μm to 3000 μm, and more preferably 100 μm to 2000 μm. By making the thickness equal to or greater than the lower limit, durability can be improved. By making the thickness equal to or less than the upper limit, flexibility can be improved.

[0033] The maximum width of the conductive portion 50 is, for example, 0.1 mm to 15 mm, preferably 0.5 mm to 12 mm, and more preferably 1 mm to 10 mm. By making the width equal to or greater than the lower limit, conductivity can be improved. By making the width equal to or less than the upper limit, durability can be improved. In a cross-sectional view taken along a plane perpendicular to the lamination direction of the double-sided conductive sheet 100, the shape of the conductive portion 50 is not particularly limited, but may be substantially circular or substantially polygonal, and specific examples include an elliptical shape, a circular shape, a rectangular shape, a polygonal shape with five or more sides, etc. The maximum width refers to the widest width of the outer shape of the conductive portion 50 in such a cross-sectional view. The shape of the conductive portion 50 may be substantially rectangular when viewed in a cross section in the stacking direction of the double-sided conductive sheet 100. In the cross section in the stacking direction of the conductive portion 50, the opening width on the upper surface side and the opening width on the lower surface side may be the same, or one of the opening widths may be larger.

[0034] In the cross section of double-sided conductive sheet 100, the thickness of the intermediate sheet is T2, and the maximum width of the conductive portion is D. D / T2 is, for example, 0.02 to 1500, preferably 0.17 to 240, and more preferably 0.5 to 100. By making it equal to or greater than the lower limit, conductivity can be improved, and by making it equal to or less than the upper limit, durability can be improved.

[0035] The upper layer and the lower layer are each a conductive sheet or a wiring.

[0036] In this embodiment, the characteristics of each component of double-sided conductive sheet 100 can be measured by using each component as a test piece as is, or by cutting each component into a predetermined shape or stacking multiple components to a predetermined thickness. Furthermore, measurements can be performed using an elastomer used in each component, such as silicone rubber (insulating silicone rubber or conductive silicone rubber).

[0037] (Tensile strength measurement procedure) Using the elastomer, a dumbbell No. 3 test piece is prepared in accordance with JIS K6251 (2004), and the tensile strength of the dumbbell No. 3 test piece at 25°C is measured.

[0038] (Measurement conditions for breaking elongation) Using the elastomer, a dumbbell-shaped No. 3 test piece is prepared in accordance with JIS K6251 (2004), and the resulting dumbbell-shaped No. 3 test piece is measured for breaking elongation at 25°C. The breaking elongation is calculated by [gauge line movement distance (mm)] ÷ [initial gauge line distance (20 mm)] × 100.

[0039] The elastomers contained in the insulating elastomer of the intermediate sheet 20, the conductive elastomer A of the lower layer 10, the conductive elastomer B of the upper layer 30, and the conductive elastomer C of the conductive portion 50 each mean a stretchable elastic body. Examples of the elastomer that can be used include silicone rubber, urethane rubber, fluororubber, nitrile rubber, acrylic rubber, styrene rubber, chloroprene rubber, ethylene propylene rubber, etc. Among these, it is preferable to use one or more thermosetting elastomers selected from the group consisting of silicone rubber, urethane rubber, and fluororubber.

[0040] The insulating elastomer may be composed of elastomer alone or may be composed of elastomer and non-conductive filler. The insulating elastomer is preferably silicone rubber. The insulating elastomer does not contain conductive filler, but may contain non-conductive filler. Among elastomers, silicone rubber is chemically stable, has excellent mechanical strength, and is highly biocompatible.

[0041] The conductive elastomer may be configured to include an elastomer and a conductive filler. The conductive elastomer is preferably a conductive silicone rubber containing a silicone rubber and a conductive filler, and the conductive elastomer may contain a non-conductive filler. By using conductive silicone rubber, stretchability and conductivity can be improved.

[0042] The conductive filler may include, for example, one or more selected from the group consisting of powder or fibrous metal-based fillers, carbon-based fillers (conductive carbon materials), metal oxide fillers, and metal-plated fillers.

[0043] As the non-conductive filler, known materials can be used, but for example, silica particles, silicone rubber particles, talc, etc. may also be used. These may be used alone or in combination of two or more. Among these, silica particles may be included.

[0044] In this embodiment, the insulating elastomer and the conductive elastomers A, B, and C may each contain the same elastomer or different elastomers, but it is preferable that they all contain silicone rubber, and it is more preferable that they all contain a cured product of a silicone rubber-based curable composition containing a vinyl group-containing organopolysiloxane.

[0045] In this specification, "containing the same silicone rubber" means that the silicone rubber-based curable composition contains at least the same type of vinyl group-containing linear organopolysiloxane, and may further contain one or more selected from the group consisting of the same type of crosslinking agent, the same type of non-conductive filler, the same type of silane coupling agent, and the same type of catalyst.

[0046] The same type of vinyl group-containing linear organopolysiloxanes are sufficient as long as they contain the same vinyl groups as functional groups and have a linear structure, but may differ in the amount of vinyl groups in the molecule, the molecular weight distribution, or the amount of vinyl groups added.

[0047] 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, different functional groups, or different amounts of functional groups added.

[0048] Non-conductive fillers of the same type may have at least a common constituent material, but may differ in particle size, specific surface area, surface treatment agent, or amount of the surface treatment agent added.

[0049] Silane coupling agents of the same type are only required to have at least a common functional group, and may differ in other functional groups in the molecule or in the amount added.

[0050] The same type of catalysts are those that have at least common constituent materials, and may contain different compositions or may have different amounts of the components added.

[0051] The silicone rubber-based curable composition constituting the same silicone rubber may further contain one or more different types of vinyl group-containing linear organopolysiloxanes, crosslinking agents, non-conductive fillers, silane coupling agents, and catalysts.

[0052] The components of the silicone rubber-based hardening composition will now be described in detail.

[0053] The silicone rubber-based curable composition of this embodiment may 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.

[0054] The vinyl group-containing organopolysiloxane (A) can contain a vinyl group-containing linear organopolysiloxane (A1) having a linear structure.

[0055] The vinyl group-containing linear organopolysiloxane (A1) has a linear structure and contains vinyl groups, which become crosslinking points during curing.

[0056] The vinyl group content of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but preferably has two or more vinyl groups in the molecule and is 15 mol% or less, which optimizes the amount of vinyl groups in the vinyl group-containing linear organopolysiloxane (A1) and ensures the formation of networks with the components described below.

[0057] In this specification, the vinyl group content refers to the mole percent of vinyl group-containing siloxane units when all units constituting the vinyl group-containing linear organopolysiloxane (A1) are taken as 100 mole percent, where it is considered that there is one vinyl group per vinyl group-containing siloxane unit.

[0058] The degree of polymerization of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but is preferably within a range of, for example, about 1,000 to 10,000, and more preferably about 2,000 to 5,000. 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.

[0059] 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.

[0060] 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.

[0061] As the vinyl group-containing linear organopolysiloxane (A1), those having a structure represented by the following formula (1) are particularly preferred.

[0062] [ka]

[0063] In formula (1), R 1is a hydrocarbon group selected from substituted or unsubstituted alkyl groups, alkenyl groups, aryl groups, or combinations thereof having 1 to 10 carbon atoms. Examples of alkyl groups having 1 to 10 carbon atoms include methyl groups, ethyl groups, and propyl groups, with methyl groups being preferred. Examples of alkenyl groups having 1 to 10 carbon atoms include vinyl groups, allyl groups, and butenyl groups, with vinyl groups being preferred. Examples of aryl groups having 1 to 10 carbon atoms include phenyl groups.

[0064] Also, R 2 is a substituted or unsubstituted alkyl group, alkenyl group, aryl group, or a hydrocarbon group combining these groups, each having 1 to 10 carbon atoms. Examples of alkyl groups having 1 to 10 carbon atoms include methyl, ethyl, and propyl groups, with methyl being preferred. Examples of alkenyl groups having 1 to 10 carbon atoms include vinyl, allyl, and butenyl groups. Examples of aryl groups having 1 to 10 carbon atoms include phenyl groups.

[0065] Also, R 3 is a substituted or unsubstituted alkyl group or aryl group having 1 to 8 carbon atoms, or a hydrocarbon group consisting of a combination thereof. Examples of alkyl groups having 1 to 8 carbon atoms include methyl, ethyl, and propyl groups, with methyl being preferred. Examples of aryl groups having 1 to 8 carbon atoms include phenyl groups.

[0066] 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.

[0067] 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 is true for .

[0068] 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.

[0069] Specific examples of the vinyl group-containing linear organopolysiloxane (A1) represented by formula (1) include those represented by the following formula (1-1).

[0070] [ka]

[0071] 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.

[0072] The vinyl group-containing linear organopolysiloxane (A1) may contain a first vinyl group-containing linear organopolysiloxane (A1-1) having two or more vinyl groups in the molecule and having a vinyl group content of 0.4 mol% or less. The vinyl group content of the first vinyl group-containing linear organopolysiloxane (A1-1) may be 0.1 mol% or less.

[0073] The vinyl group-containing linear organopolysiloxane (A1) may also contain a first vinyl group-containing linear organopolysiloxane (A1-1) and a second vinyl group-containing linear organopolysiloxane (A1-2) having a vinyl group content of 0.5 to 15 mol %.

[0074] By combining a first vinyl-containing linear organopolysiloxane (A1-1) with a second vinyl-containing linear organopolysiloxane (A1-2) having a high vinyl group content as the raw rubber used to make the silicone rubber, the vinyl groups can be unevenly distributed, allowing for more effective formation of a crosslink density distribution within the crosslinked network of the silicone rubber, thereby more effectively increasing the tear strength of the silicone rubber.

[0075] Specifically, as the vinyl group-containing linear organopolysiloxane (A1), it is preferable to use, for example, a first vinyl group-containing linear organopolysiloxane (A1-1) having two or more units in which R1 is a vinyl group and / or units in which R2 is a vinyl group in the molecule, and containing 0.4 mol % or less of these units, and a second vinyl group-containing linear organopolysiloxane (A1-2) containing 0.5 to 15 mol % of units in which R1 is a vinyl group and / or units in which R2 is a vinyl group, in the above formula (1-1).

[0076] 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 %.

[0077] 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.

[0078] 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.

[0079] The vinyl group-containing organopolysiloxane (A) may also contain a vinyl group-containing branched organopolysiloxane (A2) having a branched structure.

[0080] <<Organohydrogenpolysiloxane (B)>> The silicone rubber-based curable composition of this embodiment 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 may contain either one or both of these.

[0081] 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 the components blended into the silicone rubber-based curable composition, thereby crosslinking these components.

[0082] 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.

[0083] The weight average molecular weight of the linear organohydrogenpolysiloxane (B1) can be measured, for example, by gel permeation chromatography (GPC) using chloroform as a developing solvent, in terms of polystyrene.

[0084] Furthermore, it is generally preferred that the linear organohydrogenpolysiloxane (B1) does not contain a vinyl group, which can reliably prevent the crosslinking reaction from proceeding within the molecule of the linear organohydrogenpolysiloxane (B1).

[0085] As the linear organohydrogenpolysiloxane (B1) described above, for example, one having a structure represented by the following formula (2) is preferably used.

[0086] [ka]

[0087] In formula (2), R 4 is a substituted or unsubstituted alkyl group, alkenyl group, aryl group, a hydrocarbon group combining these, 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, 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. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

[0088] Also, R 5 is a substituted or unsubstituted alkyl group, alkenyl group, aryl group, a hydrocarbon group combining these, 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, 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. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

[0089] 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 multiple R 4 and R 5 At least two of these are hydride groups.

[0090] Also, R 6is a substituted or unsubstituted alkyl group or aryl group having 1 to 8 carbon atoms, or a hydrocarbon group combining these. Examples of alkyl groups having 1 to 8 carbon atoms include methyl groups, ethyl groups, and propyl groups, with methyl groups being preferred. Examples of aryl groups having 1 to 8 carbon atoms include phenyl groups. 6 are independent of each other and may be different from each other or may be the same.

[0091] In addition, R in formula (2) 4 ,R 5 ,R 6 Examples of the substituent include a methyl group and a vinyl group, and a methyl group is preferred from the viewpoint of preventing intramolecular crosslinking reactions.

[0092] 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.

[0093] The linear organohydrogenpolysiloxane (B1) may be used alone or in combination of two or more.

[0094] Because the branched organohydrogenpolysiloxane (B2) has a branched structure, it forms regions with high crosslink density, and is a component that significantly contributes to the formation of a sparsely crosslinked structure in the silicone rubber system. Like the linear organohydrogenpolysiloxane (B1), it has a structure in which hydrogen is directly bonded to silicon (≡Si-H), and undergoes a hydrosilylation reaction with the vinyl groups of the vinyl-group-containing organopolysiloxane (A) and with the vinyl groups of other components incorporated into the silicone rubber-based curable composition, forming a polymer that crosslinks these components.

[0095] The specific gravity of the branched organohydrogenpolysiloxane (B2) is in the range of 0.9 to 0.95.

[0096] Furthermore, it is generally preferred that the branched organohydrogenpolysiloxane (B2) does not contain vinyl groups, which can reliably prevent crosslinking reactions from occurring within the molecules of the branched organohydrogenpolysiloxane (B2).

[0097] The branched organohydrogenpolysiloxane (B2) is preferably one represented by the following average composition formula (c).

[0098] 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)

[0099] In formula (c), R 7 is a monovalent organic group, preferably a substituted or unsubstituted alkyl group or aryl group having 1 to 10 carbon atoms, or a hydrocarbon group consisting of a combination thereof. Examples of alkyl groups having 1 to 10 carbon atoms include methyl, ethyl, and propyl groups, with methyl being preferred. Examples of aryl groups having 1 to 10 carbon atoms include phenyl groups.

[0100] 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, preferably 1.

[0101] 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 The number of units.

[0102] The branched organohydrogenpolysiloxane (B2) has a branched structure. The linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2) differ in their structures, that is, whether they are linear or branched. The number of alkyl groups R bonded to Si (R / Si), where 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).

[0103] Because the branched organohydrogenpolysiloxane (B2) has a branched structure, it leaves a residue amount of 5% or more when heated, for example, in a nitrogen atmosphere to 1000°C at a heating rate of 10°C / min. In contrast, because the linear organohydrogenpolysiloxane (B1) is linear, it leaves almost no residue amount after heating under the above conditions.

[0104] Specific examples of the branched organohydrogenpolysiloxane (B2) include those having a structure represented by the following formula (3).

[0105] [ka]

[0106] In formula (3), R 7 R is a substituted or unsubstituted alkyl group or aryl group having 1 to 8 carbon atoms, or a hydrocarbon group combining these, or a hydrogen atom. Examples of alkyl groups having 1 to 8 carbon atoms include methyl, ethyl, and propyl groups, with methyl being preferred. Examples of aryl groups having 1 to 8 carbon atoms include phenyl groups. 7 Examples of the substituent include a methyl group.

[0107] 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.

[0108] In addition, in formula (3), "-O-Si≡" indicates that Si has a branched structure that spreads three-dimensionally.

[0109] The branched organohydrogenpolysiloxane (B2) may be used alone or in combination of two or more.

[0110] Furthermore, 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 groups in the vinyl group-containing linear organopolysiloxane (A1). This ensures the reliable formation of a crosslinked network between the linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2) and the vinyl group-containing linear organopolysiloxane (A1).

[0111] <<Silica particles (C)>> The silicone rubber-based curable composition of this embodiment may contain silica particles (C) as a non-conductive filler, if necessary.

[0112] The silica particles (C) are not particularly limited, but examples thereof include fumed silica, calcined silica, precipitated silica, etc. These may be used alone or in combination of two or more.

[0113] The silica particles (C) have a specific surface area of, for example, 50 to 400 m2 as measured by the BET method. 2 / g, and 100 to 400m 2 / g. 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.

[0114] By using silica particles (C) having a specific surface area and average particle size within the above ranges, it is possible to improve the hardness and mechanical strength of the silicone rubber formed, particularly the tensile strength.

[0115] <<Silane coupling agent (D)>> The silicone rubber-based curable composition of this embodiment may contain a silane coupling agent (D). The silane coupling agent (D) may have a hydrolyzable group, which is hydrolyzed by water to form a hydroxyl group, which undergoes a dehydration condensation reaction with the hydroxyl groups on the surface of the silica particles (C), thereby modifying the surface of the silica particles (C).

[0116] The silane coupling agent (D) may also contain a silane coupling agent having a hydrophobic group. This provides the surface of the silica particles (C), thereby reducing the cohesive strength of the silica particles (C) in the silicone rubber-based curable composition and, ultimately, in the silicone rubber (reducing aggregation due to hydrogen bonding via silanol groups). This is thought to result in improved dispersibility of the silica particles in the silicone rubber-based curable composition. This increases the interface between the silica particles and the rubber matrix, enhancing the reinforcing effect of the silica particles. Furthermore, it is thought that the sliding properties of the silica particles within the matrix are improved during deformation of the rubber matrix. The improved dispersibility and sliding properties of the silica particles (C) contribute to improved mechanical strength (e.g., tensile strength, tear strength, etc.) of the silicone rubber.

[0117] Furthermore, the silane coupling agent (D) may contain a silane coupling agent having a vinyl group. This introduces a vinyl group onto the surface of the silica particles (C). Therefore, during curing of the silicone rubber-based curable composition, i.e., when the vinyl groups of the vinyl group-containing organopolysiloxane (A) and the hydride groups of the organohydrogenpolysiloxane (B) undergo a hydrosilylation reaction to form a network (crosslinked structure), the vinyl groups of the silica particles (C) also participate in the hydrosilylation reaction with the hydride groups of the organohydrogenpolysiloxane (B), thereby incorporating the silica particles (C) into the network. This allows for a silicone rubber with a low hardness and a high modulus to be formed.

[0118] 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.

[0119] Examples of the silane coupling agent (D) include those represented by the following formula (4).

[0120] Y n -Si-(X) 4-n ···(4) In the above formula (4), n represents an integer of 1 to 3. Y represents a 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 the groups is a hydrophobic group. X represents a hydrolyzable group.

[0121] 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, such as a methyl group, an ethyl group, a propyl group, or a phenyl group, with a methyl group being particularly preferred.

[0122] Examples of the hydrophilic group include a hydroxyl group, a sulfonic acid group, a carboxyl group, and a carbonyl group, and among these, a hydroxyl group is particularly preferred. Although a hydrophilic group may be contained as a functional group, it is preferable that the hydrophilic group is not contained from the viewpoint of imparting hydrophobicity to the silane coupling agent (D).

[0123] 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). Note that, those having a silazane group as the hydrolyzable group have structural characteristics such that (Y n -Si-) structures.

[0124] Specific examples of the silane coupling agent (D) represented by the above formula (4) include those having a hydrophobic group as a functional group, such as alkoxysilanes like methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, and decyltrimethoxysilane; chlorosilanes like methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, and phenyltrichlorosilane; and hexamethyldisilazane. Examples of the vinyl group-containing silane include alkoxysilanes such as methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, and vinylmethyldimethoxysilane; chlorosilanes such as vinyltrichlorosilane and vinylmethyldichlorosilane; and divinyltetramethyldisilazane. Among these, taking into consideration the above, hexamethyldisilazane is particularly preferred as the silane having a hydrophobic group, and divinyltetramethyldisilazane is particularly preferred as the silane having a vinyl group.

[0125] 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 setting the content of the silane coupling agent (D) to the above lower limit or more, the silicone rubber has appropriate adhesion to the flexible substrate 120, and when silica particles (C) are used, this contributes to improving the mechanical strength of the silicone rubber as a whole. Furthermore, by setting the content of the silane coupling agent (D) to the above upper limit or less, the silicone rubber can have appropriate mechanical properties.

[0126] <<Platinum or platinum compounds (E)>> The silicone rubber-based hardenable composition of this embodiment may contain platinum or a platinum compound (E). Platinum or platinum compound (E) is a catalytic component that acts as a catalyst during curing. The amount of platinum or platinum compound (E) added is a catalytic amount.

[0127] As the platinum or platinum compound (E), known compounds 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.

[0128] The platinum or platinum compound (E) may be used alone or in combination of two or more.

[0129] <<Water(F)>> Furthermore, the silicone rubber-based hardening composition of this embodiment may contain water (F) in addition to the above components (A) to (E).

[0130] Water (F) functions as a dispersion medium to disperse the components contained in the silicone rubber-based curable composition, and also contributes to the reaction between the silica particles (C) and the silane coupling agent (D). This allows the silica particles (C) and the silane coupling agent (D) to be more reliably bonded to each other in the silicone rubber, allowing the composition to exhibit uniform properties overall.

[0131] Furthermore, when water (F) is contained, its content can be appropriately set, but specifically, for example, it is preferably in the range of 10 to 100 parts by weight, more preferably in the range of 30 to 70 parts by weight, per 100 parts by weight of the silane coupling agent (D), which allows the reaction between the silane coupling agent (D) and the silica particles (C) to proceed more reliably.

[0132] (Other ingredients) Furthermore, the silicone rubber-based curable composition of this 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.

[0133] The content ratio of each component in the silicone rubber-based hardening composition is not particularly limited, but may be set, for example, as follows:

[0134] In this embodiment, the upper limit of the content of silica particles (C) may be, for example, 60 parts by weight or less, preferably 50 parts by weight or less, and more preferably 40 parts by weight or less, per 100 parts by weight of the total amount of vinyl group-containing organopolysiloxane (A). This allows for a good balance of mechanical strength, such as hardness and tensile strength. The lower limit of the content of silica particles (C) is not particularly limited, but may be, for example, 10 parts by weight or more, per 100 parts by weight of the total amount of vinyl group-containing organopolysiloxane (A).

[0135] The silane coupling agent (D) is preferably contained in an amount of 5 to 100 parts by weight, more preferably 5 to 40 parts by weight, per 100 parts by weight of the vinyl group-containing organopolysiloxane (A), which ensures improved dispersibility of the silica particles (C) in the silicone rubber-based curable composition.

[0136] The content of organohydrogenpolysiloxane (B) is preferably 0.5 to 20 parts by weight, more preferably 0.8 to 15 parts by weight, per 100 parts by weight of the total of vinyl group-containing organopolysiloxane (A), silica particles (C), and silane coupling agent (D). By keeping the content of (B) within this range, a more effective curing reaction may be achieved.

[0137] The content of platinum or platinum compound (E) refers to the catalytic amount and can be set as appropriate. Specifically, it is an amount such that the platinum group metal in this component is 0.01 to 1000 ppm by weight, preferably 0.1 to 500 ppm, relative to the total amount of vinyl group-containing organopolysiloxane (A), silica particles (C), and silane coupling agent (D). By ensuring that the content of platinum or platinum compound (E) is at or above the lower limit, the resulting silicone rubber composition can be sufficiently cured. By ensuring that the content of platinum or platinum compound (E) is at or below the upper limit, the curing rate of the resulting silicone rubber composition can be improved.

[0138] Furthermore, when water (F) is contained, its content can be appropriately set, but specifically, for example, it is preferably in the range of 10 to 100 parts by weight, more preferably in the range of 30 to 70 parts by weight, per 100 parts by weight of the silane coupling agent (D), which allows the reaction between the silane coupling agent (D) and the silica particles (C) to proceed more reliably.

[0139] <Silicone rubber manufacturing method> Next, a method for producing the silicone rubber of this embodiment will be described. In the method for producing the silicone rubber of this embodiment, a silicone rubber-based curable composition is prepared, and the silicone rubber can be obtained by curing the silicone rubber-based curable composition. Details are provided below.

[0140] First, the components of the silicone rubber-based hardening composition are mixed uniformly using any kneading device to prepare the silicone rubber-based hardening composition.

[0141] [1] For example, a predetermined amount of vinyl group-containing organopolysiloxane (A), silica particles (C), and silane coupling agent (D) are weighed, and then kneaded using any kneading device to obtain a kneaded product containing these components (A), (C), and (D).

[0142] The kneaded mixture is preferably obtained by first kneading the vinyl group-containing organopolysiloxane (A) with the silane coupling agent (D) and then kneading (mixing) the silica particles (C), which further improves the dispersibility of the silica particles (C) in the vinyl group-containing organopolysiloxane (A).

[0143] Furthermore, when obtaining this kneaded mixture, water (F) may be added to the kneaded mixture of the components (A), (C), and (D) as needed, which allows the reaction between the silane coupling agent (D) and the silica particles (C) to proceed more reliably.

[0144] Furthermore, the kneading of components (A), (C), and (D) is preferably carried out through a first step in which the components are heated at a first temperature and a second step in which the components are heated at a second temperature. This allows the surfaces of the silica particles (C) to be surface-treated with the coupling agent (D) in the first step, and allows by-products formed by the reaction between the silica particles (C) and the coupling agent (D) to be reliably removed from the kneaded mixture in the second step. If necessary, component (A) may then be added to the resulting kneaded mixture, followed by further kneading. This improves the compatibility of the components in the kneaded mixture.

[0145] The first temperature is preferably, for example, about 40 to 120° C., and more preferably, for example, about 60 to 90° C. The second temperature is preferably, for example, about 130 to 210° C., and more preferably, for example, about 160 to 180° C.

[0146] The atmosphere in the first step is preferably an inert atmosphere such as a nitrogen atmosphere, and the atmosphere in the second step is preferably a reduced pressure atmosphere.

[0147] Furthermore, the time for the first step is, for example, preferably about 0.3 to 1.5 hours, more preferably about 0.5 to 1.2 hours, and the time for the second step is, for example, preferably about 0.7 to 3.0 hours, more preferably about 1.0 to 2.0 hours.

[0148] By setting the conditions for the first and second steps as described above, the above-mentioned effects can be more significantly obtained.

[0149] [2] Next, predetermined amounts of organohydrogenpolysiloxane (B) and platinum or a platinum compound (E) are weighed out, and then, using any kneading device, components (B) and (E) are kneaded into the mixture prepared in step [1] above, thereby obtaining a silicone rubber-based curable composition. The obtained silicone rubber-based curable composition may be a paste containing a solvent.

[0150] When kneading components (B) and (E), it is preferable to first knead the mixture prepared in step [1] with the organohydrogenpolysiloxane (B), and then knead the mixture prepared in step [1] with platinum or a platinum compound (E), and then knead the respective mixtures together. This ensures that components (A) to (E) are dispersed in the silicone rubber-based curable composition without promoting the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B).

[0151] The temperature at which the components (B) and (E) are kneaded is, for example, preferably about 10 to 70°C, more preferably about 25 to 30°C, as the roll temperature.

[0152] Furthermore, the kneading time is, for example, preferably about 5 minutes to 1 hour, and more preferably about 10 to 40 minutes.

[0153] In steps [1] and [2], by maintaining the temperature within the above range, it is possible to more effectively prevent or inhibit the progress of the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B). Furthermore, by maintaining the kneading time within the above range in steps [1] and [2], it is possible to more reliably disperse the components (A) to (E) in the silicone rubber-based curable composition.

[0154] The kneading device used in each of steps [1] and [2] is not particularly limited, but for example, a kneader, a two-roll mill, a Banbury mixer (continuous kneader), a pressure kneader, etc. can be used.

[0155] Furthermore, in step [2], a reaction inhibitor such as 1-ethynylcyclohexanol may be added to the kneaded mixture, which makes it possible to more effectively prevent or inhibit the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B) even when the temperature of the kneaded mixture is set at a relatively high temperature.

[0156] [3] Next, the silicone rubber-based hardening composition is hardened to form a silicone rubber.

[0157] In this embodiment, the curing step of the silicone rubber-based curable resin composition is carried out by, for example, heating at 100 to 250°C for 1 to 30 minutes (primary curing), followed by post-baking at 200°C for 1 to 4 hours (secondary curing).

[0158] By going through the above steps, a silicone rubber consisting of a cured product of the silicone rubber-based curable resin composition is obtained.

[0159] [3] Next, the silicone rubber-based curable composition obtained in step [2] is dissolved in a solvent to obtain an insulating paste. [3] Next, the silicone rubber-based curable composition obtained in step [2] is dissolved in a solvent, and a conductive filler is added to the solution to obtain a conductive paste.

[0160] (solvent) The conductive paste and the insulating paste contain a solvent. As the solvent, various known solvents can be used, including, for example, high-boiling point solvents, which may be used alone or in combination of two or more.

[0161] The lower limit of the boiling point of the high-boiling solvent is, for example, 100°C or higher, preferably 130°C or higher, and more preferably 150°C or higher. This can improve printing stability in screen printing and the like. On the other hand, the upper limit of the boiling point of the high-boiling solvent is not particularly limited, but may be, for example, 300°C or lower, 290°C or lower, or 280°C or lower. This can suppress excessive thermal history during wiring formation, thereby preventing damage to the substrate and maintaining a good shape of the wiring formed from the conductive paste.

[0162] The solvent can be appropriately selected from the viewpoint of the solubility and boiling point of the silicone rubber-based curable resin composition, and may include, for example, an aliphatic hydrocarbon having 5 to 20 carbon atoms, preferably an aliphatic hydrocarbon having 8 to 18 carbon atoms, and more preferably an aliphatic hydrocarbon having 10 to 15 carbon atoms.

[0163] 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, mesitylene, trifluoromethylbenzene, and benzotrifluoride; diethyl ether, diisopropyl ether, dibutyl ether, cyclopentyl methyl ether, cyclopentyl ethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, and diethylene glycol. Examples of such solvents include ethers 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; sulfoxides such as dimethyl sulfoxide and diethyl sulfoxide; and esters such as diethyl carbonate. These may be used alone or in combination of two or more. The solvent used here may be appropriately selected from among solvents that can uniformly dissolve or disperse the components in the conductive paste.

[0164] The above solvents are the polarity term of the Hansen solubility parameters (δ p ) is, for example, 10 MPa 1 / 2 or less, preferably 7 MPa 1 / 2 or less, more preferably 5.5 MPa 1 / 2 The silicone rubber-based curable resin composition may contain a first solvent having the following polarity term (δ) of the first solvent. This makes it possible to improve the dispersibility and solubility of the silicone rubber-based curable resin composition in the paste. p The lower limit of the pressure is not particularly limited, but may be, for example, 0 Pa. 1 / 2 More than that is fine.

[0165] The hydrogen bond term (δ h ) is, for example, 20 MPa 1 / 2 or less, preferably 10 MPa 1 / 2 More preferably, it is 7 MPa or less. 1 / 2 This allows the silicone rubber-based curable resin composition to have good dispersibility and solubility in the paste. h The lower limit of the pressure is not particularly limited, but may be, for example, 0 Pa. 1 / 2 More than that is fine.

[0166] Hansen solubility parameter (HSP) is an index that indicates the solubility of a substance, i.e., how much a substance dissolves in another substance. HSP expresses solubility as a three-dimensional vector. This three-dimensional vector is typically expressed as a dispersion term (δ d ), polarity term (δ p ), hydrogen bond term (δ h ) and those with similar vectors can be judged to have high solubility. The similarity of vectors can be judged by the distance of the Hansen solubility parameter (HSP distance).

[0167] The Hansen Solubility Parameters (HSP values) used in this specification can be calculated using software called HSPiP (Hansen Solubility Parameters in Practice). The computer software HSPiP, developed by Hansen and Abbott, includes a function for calculating HSP distances and a database listing the Hansen parameters for various resins and solvents or non-solvents. The solubility of each resin in pure solvents and mixed solvents of good and poor solvents is investigated, and the results are entered into the HSPiP software to calculate D: dispersion term, P: polar term, H: hydrogen bond term, and R0: radius of the solubility sphere.

[0168] As the solvent of this embodiment, for example, one can be selected that has a small difference in HSP distance, polarity term, or hydrogen bond term between the silicone rubber or the structural units that make up the silicone rubber and the solvent.

[0169] The lower limit of the viscosity of the conductive paste and / or insulating paste when measured at a shear rate of 20 [1 / s] at room temperature 25°C is, for example, 1 Pa·s or more, preferably 5 Pa·s or more, and more preferably 10 Pa·s or more. This can improve film-forming properties. Also, shape retention can be improved even when forming a thick film. On the other hand, the upper limit of the viscosity of the conductive paste and / or insulating paste at room temperature 25°C is, for example, 100 Pa·s or less, preferably 90 Pa·s or less, and more preferably 80 Pa·s or less. This can improve the printability of the paste.

[0170] At room temperature of 25°C, the viscosity measured at a shear rate of 1 [1 / s] is η1, the viscosity measured at a shear rate of 5 [1 / s] is η5, and the thixotropy index is the viscosity ratio (η1 / η5). In this case, the lower limit of the thixotropic index of the conductive paste and / or insulating paste is, for example, 1.0 or more, preferably 1.1 or more, and more preferably 1.2 or more. This allows the shape of the wiring obtained by the printing method to be stably maintained. On the other hand, the upper limit of the thixotropic index of the conductive paste and / or insulating paste is, for example, 3.0 or less, preferably 2.5 or less, and more preferably 2.0 or less. This allows the paste to be more easily printed.

[0171] The content of the silicone rubber-based curable composition in the insulating paste is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, based on 100% by mass of the insulating paste. The content of the silicone rubber-based curable composition in the insulating paste is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less, based on 100% by mass of the insulating paste.

[0172] (Conductive filler) As the conductive filler, a known conductive material may be used, but metal powder (G) or a conductive carbon material may also be used. The metal constituting the metal powder (G) is not particularly limited, but may include, for example, at least one of copper, silver, gold, nickel, tin, lead, zinc, bismuth, antimony, or alloys thereof, or two or more of these metal powders. Among these, the metal powder (G) preferably contains silver or copper, i.e., silver powder or copper powder, due to their high conductivity and availability. These metal powders (G) may also be coated with other metals.

[0173] Examples of conductive carbon materials include conductive carbon black, carbon nanotubes, and graphene.

[0174] In this embodiment, the shape of the metal powder (G) is not limited, and conventionally used shapes such as dendritic, spherical, scale-like, etc. Among these, scale-like metal powder (G) may be used.

[0175] The particle size of the metal powder (G) is not limited, but for example, the average particle size D 50 The particle size of the metal powder (G) is, for example, an average particle size D 50It is preferably 1,000 μm or less, more preferably 100 μm or less, and even more preferably 20 μm or less. Average particle size D 50 By setting the value of the thickness of the silicone rubber in this range, the silicone rubber can exhibit an appropriate electrical conductivity. The particle size of the metal powder (G) can be defined as the average particle size of 200 arbitrarily selected metal powder particles, for example, by observing the conductive paste or silicone rubber molded using the conductive paste with a transmission electron microscope or the like and performing image analysis.

[0176] The content of the conductive filler in the conductive paste is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, based on the total weight of the conductive paste, and is preferably 85% by mass or less, more preferably 75% by mass or less, and even more preferably 65% ​​by mass or less, based on the total weight of the conductive paste. By setting the content of the conductive filler to the above lower limit or more, the silicone rubber can have appropriate conductive properties, and by setting the content of the conductive filler to the above upper limit or less, the silicone rubber can have appropriate flexibility.

[0177] The content of the silicone rubber-based curable composition in the conductive paste 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% by mass of the conductive paste. The content of the silicone rubber-based curable composition in the conductive paste is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, based on 100% by mass of the conductive paste. By adjusting the content of the silicone rubber-based curable composition to be equal to or greater than the lower limit, the silicone rubber can have an appropriate degree of flexibility, while by adjusting the content of the silicone rubber-based curable composition to be equal to or less than the upper limit, the mechanical strength of the silicone rubber can be improved.

[0178] The lower limit of the content of the silica particles (C) in the conductive paste can be, for example, 1% by mass or more, preferably 3% by mass or more, and 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. This can improve the mechanical strength of the silicone rubber. On the other hand, the upper limit of the content of the silica particles (C) in the conductive paste can be, for example, 20% by mass or less, preferably 15% by mass or less, and 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. This can achieve a balance between the elastic electrical properties and the mechanical strength of the silicone rubber.

[0179] The content of the conductive filler contained in at least one of the lower layer 10, upper layer 30, and conductive portion 50 may be 50% by mass or more and 90% by mass or less in 100% by mass of the respective conductive elastomers A, B, and C. The lower limit of the content of the conductive filler in at least one of the conductive elastomers A, B, and C is, for example, 50% by mass or more, preferably 60% by mass or more, and more preferably 70% by mass or more, based on 100% by mass of the conductive elastomer, thereby improving the stretch electrical properties. On the other hand, the upper limit of the content of the conductive filler in at least one of the conductive elastomers A, B, and C is, for example, 90% by mass or less, preferably 85% by mass or less, based on 100% by mass of the conductive elastomer, thereby making it possible to suppress deterioration of rubber properties such as stretchability.

[0180] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0181] 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.

[0182] The raw material ingredients shown in Table 1 are as follows: (A1-1): First vinyl group-containing linear organopolysiloxane: 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: A vinyl group-containing dimethylpolysiloxane (having the structure represented by the above formula (1-1) and R 1 and R 2 is a vinyl group)

[0183] (Organohydrogenpolysiloxane (B)) (B-1): Organohydrogenpolysiloxane: Momentive Corporation, "TC-25D"

[0184] (Silica particles (C)) (C): Silica microparticles (particle size 7 nm, specific surface area 300 m 2 / g), Nippon Aerosil Co., Ltd., "AEROSIL300"

[0185] (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)"

[0186] (Platinum or platinum compounds (E)) (E-1): Platinum compound (manufactured by Momentive, product name "TC-25A")

[0187] (Water(F)) (F):Pure water

[0188] (Metal powder (G)) (G1): Silver powder, manufactured by Tokuriki Chemical Laboratory Co., Ltd., product name "TC-101", median diameter d 50 :8.0μm, aspect ratio 16.4, average major axis 4.6μm

[0189] (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). Specifically, 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 condenser and stirring blade and purged with Ar gas, and the mixture was heated to 120° C. and stirred for 30 minutes. An increase in viscosity was confirmed during this time. The temperature was then raised to 155°C and stirring was continued for 3 hours, after which 0.1 g (0.6 mmol) of 1,3-divinyltetramethyldisiloxane was added and the mixture was further stirred at 155°C for 4 hours. After another 4 hours, the mixture was diluted with 250 mL of toluene and washed three times with water. The washed organic layer was reprecipitated and purified by washing with 1.5 L of methanol several times, and the oligomer and polymer were separated. The resulting polymer was dried under reduced pressure at 60°C overnight 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 by H-NMR spectroscopy was 0.04 mol %.

[0190] [ka]

[0191] [Synthesis Scheme 2: Synthesis of Second Vinyl-Containing Linear Organopolysiloxane (A1-2)] A second vinyl group-containing linear organopolysiloxane (A1-2) was synthesized as shown in formula (6) below (Mn=2.3×10) by the same procedure as in the synthesis of (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. 5 , Mw=5.0×10 5 The vinyl group content calculated by H-NMR spectroscopy was 0.93 mol %.

[0192] [ka]

[0193] (Preparation of Silicone Rubber-Based Curable Composition) Silicone rubber-based curable compositions Samples 1 to 3 were prepared according to the following procedure. 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 adding the silica particles (C) was carried out through two steps: a first step of kneading for 1 hour under a nitrogen atmosphere at 60 to 90°C for the coupling reaction, and a second step of kneading for 2 hours under a reduced pressure atmosphere at 160 to 180°C for the removal of the by-product (ammonia).The mixture was then cooled, and the remaining 10% of the vinyl group-containing organopolysiloxane (A) was added in two portions, followed by kneading 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 kneaded with a roll to obtain silicone rubber-based curable compositions (samples 1 to 3).

[0194] (Preparation of conductive paste) 15.3 parts by weight of the obtained silicone rubber-based curable composition of Sample 1 was immersed in 34.8 parts by weight of decane (solvent), then stirred in a planetary centrifugal mixer, 65.2 parts by weight of metal powder (G1) was added, and the mixture was further kneaded in the planetary centrifugal mixer to obtain a conductive paste with a total content of silicone rubber-based curable composition and metal powder (G1) of 69.8% by weight.

[0195] [Table 1]

[0196] <Manufacturing double-sided electrode sheets> (Examples 1 to 3) The silicone rubber-based curable composition samples shown in Table 2 were pressed at 170°C and 10 MPa for 10 minutes to form into a sheet, which was then subjected to primary curing. This was then subjected to secondary curing at 200°C for 4 hours to obtain an intermediate sheet (insulating silicone rubber sheet) measuring 15 cm length x 15 cm width x thickness with the thickness (T2) shown in Table 2. Subsequently, a plurality of through holes having the maximum width (D) shown in Table 2 were formed in the obtained intermediate sheet using a blade. Next, the conductive paste was applied to one side of the intermediate sheet, and the through holes were filled with the conductive paste, followed by drying at 140° C. for 20 minutes. The conductive paste was then applied to the other side of the intermediate sheet and dried at 140° C. for 20 minutes. The resulting sheet was then cured at 180°C for 2 hours to form an upper sheet, a lower sheet, and multiple conductive parts made of conductive silicone rubber. The upper and lower sheets each had the thicknesses (T1 and T3) shown in Table 2. As a result of the above, a double-sided conductive sheet was produced, which has a structure in which a lower layer sheet, an intermediate sheet, and an upper layer sheet are stacked in that order, and which has multiple conductive parts that penetrate the intermediate layer sheet and electrically connect the lower layer sheet and the upper layer sheet.

[0197] (Comparative Example 1) The above conductive paste was applied to a release sheet with a smooth surface, dried at 140°C for 20 minutes, and cured at 180°C for 2 hours to form a sheet of conductive silicone rubber with the same thickness as the entire double-sided conductive sheet of Example 1. The sheet of conductive silicone rubber without multiple through holes was then separated from the release sheet and used as the double-sided conductive sheet of Comparative Example 1.

[0198] [Table 2]

[0199] The obtained double-sided conductive sheets were evaluated for the following items.

[0200] The same silicone rubber-based curable composition sample as that used to form the intermediate sheet was pressed at 170°C and 10 MPa for 10 minutes to form a sheet, which was then subjected to primary curing. This was then subjected to secondary curing at 200°C for 4 hours to form a 1 mm-thick sheet-like test piece (insulating silicone rubber). In addition, the conductive paste used to form the upper or lower layer sheet was dried at 140°C for 20 minutes and cured at 180°C for 2 hours to form a sheet-like test piece (conductive silicone rubber) with a thickness of 80 μm.

[0201] <Hardness> The above test pieces were stacked to a thickness of 6 mm, and the durometer hardness A of the resulting sheet-like test piece at 25° C. was measured in accordance with JIS K6253 (1997).

[0202] <Tensile strength> Using the above test pieces, the tensile strength at 25°C was measured in accordance with JIS K6251 (2004).

[0203] <Tear strength> Using the above test piece, a crescent-shaped test piece was prepared in accordance with JIS K6252 (2001), and the tear strength of the obtained crescent-shaped test piece at 25°C was measured.

[0204] <Elongation at break> The test piece was used to measure the breaking elongation in accordance with JIS K6251 (2004). The breaking elongation was calculated by [movement distance between chucks (mm)] ÷ [initial distance between chucks (60 mm)] × 100.

[0205] <Appearance evaluation> When the cross-sections of the double-sided conductive sheets of Examples 1 to 3 were observed, it was confirmed that there were no unfilled areas (unfilled areas) inside the through holes in the conductive portions made of conductive silicone rubber of any of Examples 1 to 3. Furthermore, as a result of observing both surfaces of the double-sided conductive sheets of Examples 1 to 3 and Comparative Example 1, it was confirmed that the surfaces were smooth and wrinkle-free in Examples 1 to 3. On the other hand, it was confirmed that wrinkles and roughness had occurred on the surface in Comparative Example 1.

[0206] <Evaluation of Conductive Properties> (Conductive properties immediately after fabrication) It was confirmed that all of the double-sided conductive sheets of Examples 1 to 3 and Comparative Example 1 had electrical continuity between the upper and lower surfaces.

[0207] (Conductive properties after stretching test) A stretching test was carried out on the double-sided conductive sheets of Examples 1 to 3 and Comparative Example 1, in which the double-sided conductive sheets were stretched by 30% 100 times, and the resistance between the two surfaces after the stretching test was measured. In Comparative Example 1, it is presumed that the cause was breakage, but conduction could not be confirmed after the expansion and contraction test. On the other hand, in Examples 1 to 3, it was confirmed that continuity was maintained even after the expansion and contraction test, and that the change in resistance value before and after the expansion and contraction test was within a range that would not cause any practical problems.

[0208] Compared to Comparative Example 1, the double-sided conductive sheets of Examples 1 to 3 showed results that were superior in conductive properties after the expansion and contraction test. [Explanation of symbols]

[0209] 10 Lower layer 20 Middle seat 30 upper layer 50 Conductive part 100 Double-sided conductive sheet

Claims

1. a lower layer made of a conductive elastomer A; a middle layer sheet made of an insulating elastomer; and an upper layer made of conductive elastomer B. A double-sided conductive sheet having a structure in which these are laminated in this order, At least one conductive part made of a conductive elastomer C is provided, which penetrates the middle layer sheet and electrically connects the lower layer and the upper layer. Double-sided conductive sheet.

2. The double-sided conductive sheet according to claim 1, When the breaking elongations of the lower layer, the intermediate sheet, and the upper layer are BE1, BE2, and BE3, and the tensile strengths are TS1, TS2, and TS3, respectively, A double-sided conductive sheet that satisfies BE2>BE1 and BE2>BE3, and / or TS2>TS1 and TS2>TS3.

3. The double-sided conductive sheet according to claim 2, At least one of BE2 / BE1 and BE2 / BE3 is 0.1 or more and 30 or less, and / or A double-sided conductive sheet in which at least one of TS2 / TS1 and TS2 / TS3 satisfies 0.1 or more and 20 or less.

4. The double-sided conductive sheet according to claim 1, When the thicknesses of the lower layer, the intermediate sheet, and the upper layer in the stacking direction of the double-sided conductive sheet are T1, T2, and T3, respectively, A double-sided conductive sheet that satisfies T2≧T1 and T2≧T3.

5. The double-sided conductive sheet according to claim 4, A double-sided conductive sheet, wherein at least one of T2 / T1 and T2 / T3 satisfies 0.01 or more and 1500 or less.

6. The double-sided conductive sheet according to any one of claims 1 to 4, The thickness of the intermediate sheet is 10 μm or more and 5000 μm or less, and the double-sided conductive sheet.

7. The double-sided conductive sheet according to any one of claims 1 to 4, The maximum width of the conductive portion is 0.1 mm or more and 15 mm or less, and the double-sided conductive sheet.

8. The double-sided conductive sheet according to any one of claims 1 to 4, A double-sided conductive sheet, wherein when the thickness of the intermediate sheet is T2 and the maximum width of the conductive portion is D, D / T2 is 0.02 or more and 1500 or less.

9. The double-sided conductive sheet according to any one of claims 1 to 4, A double-sided conductive sheet used for bioelectrodes.

10. The double-sided conductive sheet according to any one of claims 1 to 4, A double-sided conductive sheet, wherein at least one of the conductive elastomers A, B, and C comprises a conductive silicone rubber containing a conductive filler.

11. The double-sided conductive sheet according to claim 10, A double-sided conductive sheet, wherein the content of the conductive filler in at least one of the lower layer, the upper layer, and the conductive portion is 50% by mass or more and 90% by mass or less.

12. The double-sided conductive sheet according to any one of claims 1 to 4, A double-sided conductive sheet, wherein the insulating elastomer comprises insulating silicone rubber.

13. The double-sided conductive sheet according to any one of claims 1 to 4, A double-sided conductive sheet, wherein the upper layer and the lower layer are each a conductive sheet or a wiring.

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