JP5722257B2 - Liquid sensing sheet - Google Patents

Description

  The present invention relates to a liquid sensing sheet for detecting a liquid such as water or oil.

  Conventionally, as a liquid sensing sheet used for a sensor for detecting water leakage, a pair of metal net-like sheets or electrode tapes are connected with a water-based insulating sheet, and the peripheral portion of the laminate of these sheets is bonded with an adhesive. Have been proposed (Patent Documents 1 and 2).

JP 2007-143895 A JP-A-57-66336

  Since the conventional liquid sensing sheet has an integrated configuration by adhering the peripheral edge, it is necessary to use the integrated shape and size as a unit. However, the location where water leakage is detected is often in various sizes and shapes, such as a location smaller than the unit size of the conventional liquid sensing sheet, so there are many cases where the conventional liquid sensing sheet cannot be applied. is there.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a liquid sensing sheet having a high degree of freedom of application.

The present invention is a liquid sensing sheet having the following configuration, comprising a liquid-permeable insulating sheet that exhibits conductivity by a liquid, and a conductive sheet bonded to both surfaces of the insulating sheet. At least one of the conductive sheets has a penetrating portion that allows the liquid to pass therethrough, and the insulating sheet and the conductive sheet are joined together by an adhesive that is dispersedly disposed on the entire joining surface, and the adhesive Are partially disposed on the surface of the conductive sheet.

  According to the above configuration, since the insulating sheet and the conductive sheet can be bonded to the entire surface by the adhesive dispersedly disposed on the entire bonding surface, the same sensing performance can be obtained even if the desired size or shape is cut. And a liquid sensing sheet having bonding strength. In other words, in the case of the configuration in which the peripheral edge of the sheet is joined with an adhesive as in the conventional case, the size and shape are limited. However, according to the above configuration, the size and shape can be arbitrarily changed. The liquid sensing sheet can have a high degree of freedom.

  The conductive sheet in the present invention may be a metal layer. According to said structure, since the area | region of the clearance gap of the adhesive agent arrange | positioned disperse | distributed becomes an exposed surface of an electroconductive sheet, and this exposed surface becomes a flat metal layer, it is a conductive state in the whole part except a penetration part. The presence or absence can be sensed.

  The metal layer in the present invention may be a metal foil. According to said structure, it can further be set as a flexible liquid sensing sheet.

This invention has the protective sheet arrange | positioned on the surface on the opposite side to the said insulating sheet in the said conductive sheet which has the said penetration part, and the said protection sheet is the said penetration part of the said adjacent conductive sheet The conductive sheet may be formed by applying a conductive paste to the protective sheet . According to the above configuration, the liquid sensing sheet can be protected from external force due to impact or rubbing, the strength of the liquid sensing sheet can be increased, and an insulating function can be provided. Moreover, since a conductive sheet can be formed by application of a conductive paste, a liquid sensing sheet can be easily obtained.

  In the present invention, the through portion may be at least one of a hole and a slit. According to said structure, it can be set as the liquid sensing sheet according to the objectives, such as a kind of liquid, a sensitivity, by the combination of 1 or more of a hole and a slit.

  In the present invention, both of the conductive sheets may have the penetrating portion, and the penetrating portions of the one conductive sheet and the other conductive sheet may be arranged so as not to overlap each other. .

  According to said structure, since the liquid which permeate | transmitted the insulating sheet from the penetration part of one electroconductive sheet is dammed up by the other electroconductive sheet, it can be set as the liquid sensing sheet which can perform a liquid sensing reliably.

  The penetrating part in the conductive sheet of the present invention may have a surfactant having surface activity with respect to the liquid attached to at least a part of the contact part with the liquid.

  According to said structure, since it becomes easy to osmose | permeate the inside of an insulating sheet with surfactant, even if it is a slight liquid, it will osmose | permeate an insulating sheet and will change from an insulation state to a conductive state. Thereby, even a small amount of liquid can be sensed, and the time until sensing can be shortened. Further, the type of surfactant can be properly used according to the type of liquid to be sensed.

  The insulating sheet in the present invention may be a nonwoven fabric. According to said structure, since the insulating sheet is formed with the nonwoven fabric, even if it is a slight liquid, it will permeate | transmit into an insulating sheet by a capillary phenomenon, and will change from an insulation state to an electroconductive state.

  The insulating sheet in the present invention may be lyophilic with respect to the liquid. According to said structure, since it is an insulating sheet which has lyophilicity with respect to the liquid, even if it is a little liquid, it will penetrate | invade an insulating sheet and will change from an insulation state to a conductive state.

  In the insulating sheet of the present invention, a surfactant having surface activity with respect to the liquid may be attached to at least a part of a contact portion with the liquid in the liquid-permeable structure.

  According to said structure, since it becomes easy to osmose | permeate the inside of an insulating sheet with surfactant, even if it is a slight liquid, it will osmose | permeate an insulating sheet and will change from an insulation state to a conductive state. Further, the type of surfactant can be properly used according to the type of liquid to be sensed.

  The insulating sheet in the present invention may have a coloring member whose color changes with the liquid.

  According to said structure, since a color changes with liquids, it can be set as the liquid sensing sheet which can sense a liquid leakage visually.

The present invention, said said insulating sheet in the conductive sheet having a through portion has a protective sheet disposed on the opposite side, the protective sheet, the through portion of the conductive sheet adjacent You may have a passage hole which overlaps.

  According to the above configuration, the liquid sensing sheet can be protected from external force due to impact or rubbing, the strength of the liquid sensing sheet can be increased, and an insulating function can be provided.

  The degree of freedom of the application target of the liquid sensing sheet can be increased.

It is explanatory drawing of a liquid sensing sheet. It is explanatory drawing which showed the relationship of arrangement | positioning of a penetration part and an adhesive agent. It is explanatory drawing which showed the relationship of arrangement | positioning of a penetration part and an adhesive agent. It is explanatory drawing which showed the relationship of arrangement | positioning of a penetration part and an adhesive agent. It is explanatory drawing which showed the relationship of arrangement | positioning of a penetration part and an adhesive agent. It is principal part sectional drawing of a liquid sensing sheet. It is explanatory drawing which showed the relationship of arrangement | positioning of a penetration part and an adhesive agent. It is explanatory drawing of a liquid sensing sheet.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(Liquid sensing sheet: overall configuration)
As shown in FIG. 1, the liquid sensing sheet 1 includes a liquid-permeable insulating sheet 4 that exhibits conductivity by a liquid, and conductive sheets 3 and 5 bonded to both surfaces of the insulating sheet 4. The conductive sheets 3 and 5 have through portions 31 and 51 that allow liquid to pass therethrough. The insulating sheet 4 and the conductive sheets 3 and 5 are bonded together by an adhesive 7 that is dispersedly arranged on the entire bonding surface. In other words, the liquid sensing sheet 1 has a configuration in which the insulating sheet 4 is disposed between the two conductive sheets 3 and 5 in a joined state.

  Here, the “liquid” is a liquid sensing object by the liquid sensing sheet 1 and is not limited to a material or physical property as long as it is liquid. The liquid state means that the insulating sheet 4 is fluid enough to be impregnated. The kind of “liquid” may be pure water or water containing impurities, or an organic substance such as acid, alkali, oil, or organic solvent. The physical property of “liquid” may be any material that is liquefied at the ambient temperature in which the liquid sensing sheet 1 is used.

  Since the liquid sensing sheet 1 configured as described above can bond the insulating sheet 4 and the conductive sheets 3 and 5 over the entire surface with an adhesive distributed over the entire bonding surface, a desired size or Even if cut into a shape, it can be used as a liquid sensing sheet having the same sensing performance and bonding strength. Thereby, since the liquid sensing sheet 1 can change a size and a shape arbitrarily, the freedom degree of application object is high.

  In addition, the liquid sensing sheet 1 is bonded to the long insulating sheet 4 and the conductive sheets 3 and 5 because the insulating sheet 4 and the conductive sheets 3 and 5 are bonded to each other by an adhesive distributed over the entire bonding surface. It is also possible to manufacture continuously by applying the agent. Furthermore, the continuously manufactured liquid sensing sheet 1 can be shipped and stored as a short type liquid sensing sheet trimmed to a predetermined length by cutting in the middle of production, and the long liquid sensing sheet. It can also be shipped and stored as a liquid sensing roll 10 in which 1 is wound into a roll. That is, the liquid sensing sheet 1 has a configuration suitable for mass production.

  The liquid sensing sheet 1 includes two protective sheets 2 and 6. The protective sheets 2 and 6 are respectively disposed on the surfaces of the conductive sheets 3 and 5 opposite to the insulating sheet 4 so as to be positioned on the front surface (one surface) and the back surface (other surface) of the liquid sensing sheet 1. Yes. These protective sheets 2 and 6 have a function of protecting the liquid sensing sheet 1 from external force due to impact and rubbing, increasing the strength of the liquid sensing sheet, and insulating functions. These protective sheets 2 and 6 have passage holes 21 and 61 that overlap the through portions 31 and 51 of the conductive sheets 3 and 5.

(Insulation sheet 4)
The insulating sheet 4 disposed at the center in the thickness direction of the liquid sensing sheet 1 has a liquid-permeable structure that exhibits conductivity by the liquid and allows the liquid to pass therethrough. That is, the insulating sheet 4 is configured to change from insulating to conductive as a whole by the permeation of liquid.

  The “liquid permeable structure” provided in the insulating sheet 4 is not limited to the material and shape as long as it is a structure that allows the liquid that is the sensing object to pass through. Examples include a nonwoven structure, a porous structure having open cells, a structure in which one or more holes are formed in a nonporous material, and a structure in which one or more slits are formed in a nonporous material. When the insulating sheet 4 is non-woven fabric or paper, even a small amount of liquid penetrates into the insulating sheet 4 due to capillary action and changes from an insulating state to a conductive state. It can be 1.

  The material of the insulating sheet 4 is not particularly limited as long as it is a material having a large electric resistance when not in contact with a liquid.

  Examples of the material of the insulating sheet 4 include cellulose such as cloth and paper, ceramic, and engineering plastic. Examples of engineering plastics include polypropylene, crosslinked polyethylene, polyester, polybenzimidazole, aramid, polyimide, polyimideamide, polyetherimide, polyphenylene sulfide (PPS), and polyethylene naphthalate (PEN).

Specifically, a nonwoven fabric made of a polyester resin manufactured by Unitika Ltd. (registered trademark: MARIX) can be used for the insulating sheet 4. This nonwoven fabric has hydrophilicity because the resin for adhering the polyester fibers is a water-soluble acrylic resin. In addition, the manufacturing method of said nonwoven fabric is a spun bond method. When the nonwoven fabric product number is # 20507WTD, the basis weight is 50 g / m ² and the average thickness is 155 μm. When the nonwoven fabric product number is # 20604FLD, the basis weight is 60 g / m ² and the average thickness is 150 μm. When the nonwoven fabric product number is # 10606WTD, the basis weight is 60 g / m ² and the average thickness is 215 μm (with bulkiness).

  The thickness of the insulating sheet 4 is preferably 1 μm to 5000 μm. The insulating sheet 4 is preferably lyophilic with respect to the liquid that is the sensing object. For example, if the liquid is water, the lyophilic property is referred to as hydrophilic. In the configuration having lyophilicity, even a small amount of liquid penetrates into the insulating sheet 4 and changes from an insulating state to a conductive state. It can be set as the liquid sensing sheet 1 which shortens time.

  In addition, the lyophilic property may be that the material of the insulating sheet 4 has lyophilic property, or a lyophilic layer is formed on the surface of the lyophobic material. For example, in the insulating sheet 4, a surfactant having surface activity with respect to the liquid may be attached to at least a part of the contact portion with the liquid in the liquid-permeable structure. In this case, the liquid sensing sheet 1 that can select the sensing target such as water or oil can be obtained by properly using the type of the surfactant according to the type of the sensing target liquid.

  Furthermore, the insulating sheet 4 may have a coloring member whose color changes depending on the liquid. As a coloring member, the structure which sealed colorants, such as dye, in the capsule which melt | dissolves in the liquid which consists of solvents, such as water and oil, can be illustrated. In this case, when the capsule is melted by the liquid, the color of the insulating sheet 4 changes due to the flow of the sealed colorant, so that the liquid sensing sheet 1 that can visually detect the liquid leakage is used. Can do.

  Furthermore, the insulating sheet 4 may be attached with a dissolving material (inorganic salts: sodium chloride, sodium sulfate, calcium chloride, magnesium hydroxide, etc.) that is dissolved and ionized in a liquid. In this case, even if the liquid itself has no conductivity (such as oil), the dissolved material ionized by the liquid can change the insulating sheet 4 to be conductive.

(Conductive sheet 3.5)
Conductive sheets 3 and 5 having conductivity are bonded to both surfaces of the insulating sheet 4. The lower limit of the thickness of the conductive sheets 3 and 5 is 0.05 μm, and the upper limit of the thickness is 200 μm. In addition, when the conductive sheets 3 and 5 are formed by sputtering or vapor deposition, a thickness of 0.05 μm to 1 μm is preferable. When the conductive sheets 3 and 5 are formed by the conductive ink printing method, a thickness of 2 μm to 200 μm is preferable. When the conductive sheets 3 and 5 are formed of metal foil, the thickness is preferably 2 μm to 100 μm.

  In addition, the conductive sheets 3 and 5 have through portions 31 and 51 that allow liquid to pass therethrough. The penetration parts 31 and 51 are formed by circular holes. What is necessary is just to determine suitably the hole diameter (diameter) in the penetration parts 31 and 51 by a test, experiment, etc. with the kind of liquid. Moreover, although the aperture ratio of the penetration parts 31 and 51 should just be the range of 1%-90%, it is preferable to adjust suitably according to a use.

  In addition, the hole shape of penetration part 31 * 51 may be polygonal shapes, such as a long hole shape, an ellipse shape, and a triangle, a quadrangle, other than circular shape. The hole sizes of the through-portions 31 and 51 may be set to an extent that causes capillary action, or may be larger than liquid droplets. Moreover, the penetration parts 31 and 51 may be a combination of various shapes and sizes. For example, the outer diameter of a circular shape, an elliptical shape, a triangular shape, a quadrangular shape, a pentagonal shape, a hexagonal shape or the like formed by punching is preferably 0.1 to 30 mm.

  Further, the through portions 31 and 51 may be slits. The shape of the slit may be a straight line,-, =, a cross, or a V mark. The slit length is preferably 3 mm to 5 mm. Even in the case of the slit, it becomes possible to promote the permeation of the liquid by the capillary phenomenon. In other words, the penetration parts 31 and 51 should just be formed by at least one of the hole and the slit. As a result, the conductive sheets 3 and 5 can be made into the liquid sensing sheet 1 having various sensitivities by one or more combinations of holes and slits.

  Specifically, as shown in FIG. 2, the liquid sensing sheet 1 may have circular through portions 31 and 51 arranged in a matrix in the longitudinal direction and the width direction. In addition, it is preferable that arrangement | positioning is arrange | positioned equally in the whole surface. Further, as shown in FIG. 3, the liquid sensing sheet 1 may have elongated hole-shaped through portions 31 and 51 formed at both end portions in the width direction and arranged in the longitudinal direction at a predetermined interval. Further, as shown in FIG. 4, the liquid sensing sheet 1 may have rectangular penetrating portions 31 and 51 arranged in a lattice shape including a width direction, a longitudinal direction, and an inclination direction. According to this configuration, the work of cutting into a predetermined shape is facilitated. Further, as shown in FIG. 5, the liquid sensing sheet 1 may have circular through portions 31 and 51 and slit-like through portions 31 and 51 arranged alternately.

  Furthermore, the liquid sensing sheet 1 may be a combination of FIGS. 2 to 5, or the hole portion may be replaced with a slit. When all the penetrating parts 31 and 51 are slits, the penetrating parts 31 and 51 are formed by cutting the conductive sheets 3 and 5 using a plurality of blade parts formed on a base member such as a roll. be able to. Thereby, since the punching waste of a hole part does not remain like the case where a hole is formed by punching out the conductive sheets 3 and 5, generation of waste can be suppressed to the minimum.

  The conductive sheets 3 and 5 may be made of any material as long as they have conductivity, but are preferably metals such as aluminum and copper. The metal material for forming the conductive sheets 3 and 5 is nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, or an alloy containing two or more of these. There may be.

  The conductive sheets 3 and 5 are preferably metal layers. Here, the metal layer is a concept including a metal foil and a metal thin film. When the conductive sheets 3 and 5 are metal layers, the gaps between the dispersed adhesives 7 are exposed surfaces of the conductive sheets 3 and 5, and the exposed surfaces are flat metal layers (conductive sheets 3). Since 5), the presence or absence of the conductive state can be sensed in the entire portion excluding the through portions 31 and 51.

  Furthermore, the conductive sheets 3 and 5 are particularly preferably a metal foil. In this case, the electrical resistance is small and the sensing time can be shortened.

  The conductive sheets 3 and 5 are not limited to metal foils by rolling and metal foils by electrolysis (such as special electrolytic copper foils), but vacuum deposition, sputtering, CVD, MO (metal organic), plating, printing A metal thin film formed by, for example, may be used.

  Moreover, the conductive sheets 3 and 5 may be formed of a conductive adhesive. In this case, since the conductive sheets 3 and 5 can be formed by applying a conductive adhesive, the liquid sensing sheet 1 can be easily obtained. The conductive adhesive is a mixture composed of conductive particles and an adhesive resin, and is an adhesive that can be heat-pressed at 100 to 200 ° C. The conductive particles are metal powder or low melting point metal powder having an average particle diameter of 2 to 50 μm, and 10 to 400 parts by weight are blended with 100 parts by weight of the adhesive resin.

  Further, as shown in FIG. 1, the liquid sensing sheet 1 is disposed so that the through portions 31 and 51 of the one conductive sheet 3 and the other conductive sheet 5 do not overlap each other. That is, the penetration part 31 of one conductive sheet 3 is completely blocked by the other conductive sheet 5, and the penetration part 51 of the other conductive sheet 5 is completely blocked by the one conductive sheet 3. It is in the state. Thereby, for example, since the liquid that has permeated through the insulating sheet 4 from the penetrating portion 31 of the one conductive sheet 3 is blocked by the other conductive sheet 5, the liquid sensing sheet 1 can be reliably sensed. In addition, as for the liquid sensing sheet 1, the penetration parts 31 * 51 of the electroconductive sheets 3 * 5 may overlap partially.

  In addition, it is preferable that the conductive sheets 3 and 5 have the same thickness and material, and the shape, size, and open area ratio of the through portions 31 and 51 are the same. Thereby, since the same sensing performance is exhibited in any surface of the liquid sensing sheet 1, it is possible to eliminate the necessity of the work of attaching carefully to the surface that senses the liquid to be sensed.

  One conductive sheet 3 and the other conductive sheet 5 may have different configurations. For example, the combination shown in FIGS. When the conductive sheets 3 and 5 have different configurations, the sensing performance can be varied depending on the surface of the conductive sheets 3 and 5, so that the application target of the liquid as the sensing object can be expanded. The liquid sensing sheet 1 having two types of sensitivity can be obtained.

  When the sensing performance of the conductive sheets 3 and 5 is made different, the conductive sheets 3 and 5 can be identified by color coding or symbol notation so that an operator can distinguish the sensing performance. It is preferable. Further, as shown in FIG. 6, the liquid sensing sheet 1 may have through portions 31 and 51 in either one of the conductive sheets 3 and 5. That is, the liquid sensing sheet 1 only needs to have the through portions 31 and 51 in at least one of the conductive sheets 3 and 5.

  In the through portions 31 and 51 in the conductive sheets 3 and 5, a surfactant having surface activity with respect to the liquid may be attached to at least a part of the contact portion with the liquid. The same surfactant as that used for the insulating sheet 4 can be used. In this case, since the liquid can easily reach the insulating sheet 4 through the penetrating portions 31 and 51 by the surfactant, the insulating sheet 4 can be changed from the insulating state to the conductive state even with a small amount of liquid. It becomes possible. Further, by properly using the type of the surfactant according to the type of the liquid to be sensed, for example, the liquid sensing sheet 1 can be selected such as water or oil. In the case of oil, since it is insulative, it is necessary to attach an ionizing melting member to the through portions 31 and 51 and the insulating sheet. The surfactant may be attached to the conductive sheets 3 and 5 and the insulating sheet 4 or may be attached to any one of them.

(Adhesive 7)
The insulating sheet 4 and the conductive sheets 3 and 5 configured as described above are bonded together by an adhesive 7 that is dispersedly arranged on the entire bonding surface. Here, “distributed arrangement over the entire joint surface” is a concept including a plurality of divided linear shapes, continuous linear shapes, and a plurality of dotted shapes. The adhesive 7 is preferably dispersed. Moreover, the adhesive agent 7 may be arrange | positioned avoiding the penetration parts 31 * 51, and a part may overlap and it may be arrange | positioned.

  If the kind of the adhesive agent 7 is demonstrated in detail, water glass will be illustrated as an inorganic type adhesive agent. Examples of the natural adhesive include casein adhesive, natural rubber, natural rubber latex, starch, glue, and fibrin. Examples of the synthetic adhesive include solvent-based, water-soluble, and HM-based adhesives.

  Specifically, solvent-based synthetic adhesives include acrylic resin-based, acrylic resin-based adhesives, α-olefin-based adhesives, urethane resin-based adhesives, epoxy resin-based adhesives, and vinyl chloride resin solvent-based adhesives. , Chloroprene rubber adhesive, cyanoacrylate adhesive, silicone adhesive, styrene-butadiene rubber solution adhesive, nitrile rubber adhesive, nitrocellulose adhesive, modified silicone adhesive, polyimide adhesive, poly Vinyl acetate resin solution adhesive, polystyrene resin solvent adhesive, polyvinyl alcohol adhesive, polyvinyl pyrrolidone resin adhesive, polyvinyl butyral resin adhesive, polybenzimidazole adhesive, polymethacrylate resin solution adhesive Is exemplified.

  As water-based synthetic adhesives, ether cellulose, acrylic resin emulsion adhesive, urethane resin emulsion adhesive, ethylene-vinyl acetate resin emulsion adhesive, epoxy resin emulsion adhesive, vinyl acetate resin emulsion adhesive, Examples include aqueous polymer-isocyanate adhesives, styrene-butadiene rubber latex adhesives, phenol resin adhesives, modified silicone adhesives, melamine resin adhesives, urea resin adhesives, and resorcinol adhesives. .

  Examples of HM synthetic adhesives include ethylene-vinyl acetate resin hot melt adhesives, reactive hot melt adhesives, polyamide resin hot melt adhesives, polyurethane resin hot melt adhesives, and polyolefin resin hot melt adhesives. The

  Among the adhesives exemplified above, the HM (hot melt) system is preferable. The reason for this is that it contains no solvent or water compared to other adhesives, and the amount when cured and the amount before curing do not change, so the amount of adhesive can be reduced, so it can be applied according to the pattern. Because it can. Pattern coatings such as HM-based ethylene-vinyl acetate resin hot melt adhesives, polyamide resin hot melt adhesives, and polyurethane resin hot melt adhesives are preferred.

  The adhesive 7 can be a conductive adhesive. When a conductive adhesive is used for the adhesive 7, the adhesive 7 itself can be made conductive, so that the sensing performance of the liquid sensing sheet 1 can be improved. As the conductive adhesive, either an isotropic conductive adhesive or an anisotropic conductive adhesive may be used.

(Protective sheet 2.6)
Protective sheets 2 and 6 are respectively disposed on the surfaces of the conductive sheets 3 and 5 opposite to the insulating sheet 4. These protective sheets 2 and 6 cover the conductive sheets 3 and 5 so that they are not directly exposed to the outside, thereby protecting the liquid sensing sheet 1 from external force due to impact and rubbing, increasing the strength of the liquid sensing sheet, and insulating it. Has a function. The protective sheets 2 and 6 have passage holes 21 and 61 that overlap the through portions 31 and 51 of the conductive sheets 3 and 5. The passage holes 21 and 61 may have any shape or size that overlaps with the through portions 31 and 51. The passage holes 21 and 61 may be attached with the above-mentioned surfactant or a dissolving member that dissolves into a liquid and is ionized.

  The protective sheets 2 and 6 may be formed of paper or non-woven fabric, or may be formed of an epoxy resin, a polyester resin, an acrylic resin, a phenol resin, a urethane resin, or a mixture thereof. In addition, although the thickness of the protective sheets 2 and 6 is 5 micrometers-200 micrometers, it does not need to be specifically limited and can be set suitably. In addition, when the protective sheets 2 and 6 are formed of a PET film, it is desirable that the surface of the PET film is subjected to a hydrophilic treatment. The hydrophilic treatment is a hydrophilic resin coat, corona treatment, plasma treatment, or the like.

  The protective sheets 2 and 6 and the conductive sheets 3 and 5 are bonded by an adhesive 8. The adhesive 8 may be the same material as the adhesive 7 described above, or may be a different material. Further, the adhesive 8 may be arranged in a distributed manner, or may be arranged on the entire joint surface between the protective sheets 2 and 6 and the conductive sheets 3 and 5. When the conductive sheets 3 and 5 are formed by applying a conductive paste to the protective sheets 2 and 6, the adhesive 8 can be omitted.

(Manufacturing method of the liquid sensing sheet 1)
In the above configuration, a method for manufacturing the liquid sensing sheet 1 will be described. In addition, the numerical value in description of a manufacturing method is an illustration, and can be changed suitably. First, a 12 μm PET (Polyethylene terephthalate) film, paper, and nonwoven fabric are prepared as the insulating sheet 4. In the case of a PET film, it is processed so that a plurality of holes and slits are evenly dispersed so as to have a liquid-permeable structure.

  6 μm copper foil and 9 μm aluminum foil are prepared as the conductive sheets 3 and 5, and 12 μm PET film, paper, and nonwoven fabric are prepared as the protective sheets 2 and 6. Then, the protective sheets 2 and 6 are joined to the conductive sheets 3 and 5 via the adhesive 8. Thereafter, through holes 31 and 51 and through holes 21 and 61 are formed by drilling and slitting the integrated conductive sheets 3 and 5 and protective sheets 2 and 6.

  Next, the adhesive 7 is evenly dispersed and applied to the surfaces of the conductive sheets 3 and 5 with the protective sheets 2 and 6 subjected to drilling and slit processing. The conductive sheets 3 and 5 with the protective sheets 2 and 6 are laminated on the insulating sheet 4 so that the surface to which the adhesive 7 is applied contacts the insulating sheet 4 described above. In addition, lamination | stacking of the insulating sheet 4 and the electroconductive sheets 3 * 5 may be performed at the same timing with respect to both surfaces of the insulating sheet 4, and may be performed at a different timing. Further, the adhesive 7 may be applied to the insulating sheet 4. Thereafter, the laminated member of the protective sheets 2 and 6, the conductive sheets 3 and 5, and the insulating sheet 4 is heated to cure the adhesive 7, whereby the liquid sensing sheet 1 of FIG. 1 is manufactured.

  The manufacturing method described above may be performed in batch units by dividing the protective sheets 2 and 6, the conductive sheets 3 and 5, and the insulating sheet 4 into predetermined dimensions, or by forming a long strip. It may be performed continuously. In addition, the manufacturing method described above has an advantage that the thin liquid sensing sheet 1 can be manufactured, and any position of the liquid sensing sheet 1 can be cut and used as a sensor, that is, it can be manufactured with high yield.

(Application example of liquid sensing sheet 1)
The liquid sensing sheet 1 manufactured as described above is installed by being wound or placed on a device or a location that is a sensing target of leakage. At this time, it is cut with a scissors, a cutter, a punching die or the like so as to be optimal for the shape and size of the installation place. When the optimum shape and size are obtained, the conductive sheets 3 and 5 are connected as electrode terminals to a measuring device such as an ammeter. That is, the liquid sensing sheet 1 is used as a leak sensor.

  When leakage occurs in the sensing object, the liquid adheres to the surface of the liquid sensing sheet 1. The liquid passes through the through holes 21 and 61 and the through portions 31 and 51 to reach one surface of the insulating sheet 4 and permeates into the insulating sheet 4 due to the liquid-permeable structure of the insulating sheet 4. And when a liquid reaches | attains the other surface of the insulating sheet 4, the insulating sheet 4 will exhibit electroconductivity and between the electroconductive sheets 3 * 5 will switch from an insulation state to a conductive state. As a result, the occurrence of liquid leakage is detected when the measuring device detects a change in electrical resistance.

(Modification of liquid sensing sheet 1)
In this embodiment, although the case where the electroconductive sheets 3 and 5 and the insulating sheet 4 were joined using the adhesive agent 7 was demonstrated, it is not limited to this. More specifically, as shown in FIG. 7, the liquid sensing sheet 101 includes a liquid-permeable insulating sheet 4 that exhibits conductivity by a liquid, and a conductive adhesive bonded to both surfaces of the insulating sheet 4. The conductive sheets 3 and 5 may be provided, and at least one of the conductive sheets 3 and 5 may be configured to have through portions 31 and 51 through which the liquid passes.

  According to the above configuration, since the conductive sheets 3 and 5 made of a conductive adhesive and the insulating sheet 4 can be bonded over the entire surface, even if the desired size and shape are cut out, the same sensing performance and It can be used as a liquid sensing sheet 101 having bonding strength. In other words, in the case of the configuration in which the peripheral edge of the sheet is joined with an adhesive as in the conventional case, the size and shape are limited. However, according to the above configuration, the size and shape can be arbitrarily changed. The liquid sensing sheet 101 can have a high degree of freedom. Furthermore, since the conductive sheets 3 and 5 themselves can be bonded to the insulating sheet 4, it is not necessary to use the adhesive 7 in FIG. 1, so that the liquid sensing sheet 101 having a simple configuration can be easily obtained. Can do.

  Here, the conductive adhesive for the conductive sheets 3 and 5 is preferably an isotropic conductive adhesive, but may be an anisotropic conductive adhesive. The isotropic conductive adhesive ensures an electrically conductive state in all three directions including the thickness direction, the width direction, and the longitudinal direction of the conductive sheets 3 and 5. The conductive adhesive is formed by adding a conductive filler to the adhesive. If flame retardancy is required, add a flame retardant.

  When a conductive adhesive is applied to the conductive sheets 3 and 5 of the liquid sensing sheet 1, the lower limit of the thickness of the conductive sheets 3 and 5 is 5 μm, and preferably 10 μm. Moreover, the upper limit of thickness is 100 micrometers, and 50 micrometers is preferable.

  The adhesive contained in the conductive adhesive is an adhesive resin, such as a thermoplastic resin such as polystyrene, vinyl acetate, polyester, polyethylene, polypropylene, polyamide, rubber, acrylic, phenolic, It consists of thermosetting resins such as epoxy, urethane, melamine, and alkyd. The adhesive may be a single substance or a mixture of the above resins. The adhesive may further contain a tackifier. Examples of the tackifier include tackifiers such as fatty acid hydrocarbon resins, C5 / C9 mixed resins, rosin, rosin derivatives, terpene resins, aromatic hydrocarbon resins, and thermally reactive resins.

  Part or all of the conductive filler added to the conductive adhesive is formed of a metal material. For example, conductive fillers include copper powder, silver powder, nickel powder, silver coated copper powder (Ag coated Cu powder), gold coated copper powder, silver coated nickel powder (Ag coated Ni powder), and gold coated nickel powder. The metal powder can be produced by an atomizing method, a carbonyl method, or the like. In addition to the above, particles obtained by coating a metal powder with a resin and particles obtained by coating a resin with a metal powder can also be used. Furthermore, one or more kinds of conductive fillers may be mixed and added to the conductive adhesive. The conductive filler is preferably Ag-coated Cu powder or Ag-coated Ni powder. This is because conductive particles having stable conductivity can be obtained from an inexpensive material.

  The conductive filler is added in the range of 10 wt% to 400 wt% with respect to the adhesive resin. Moreover, although the average particle diameter of a conductive filler has the preferable range of 2 micrometers-50 micrometers, what is necessary is just to select an optimal value with the thickness of the conductive sheets 3.5. The shape of the metal filler may be any of a spherical shape, a needle shape, a fiber shape, a flake shape, and a resin shape.

  As the flame retardant, a non-halogen flame retardant is preferable from an environmental problem. Nitrogen flame retardant such as melamine cyanurate and melamine polyphosphate, metal hydrate such as magnesium hydroxide and aluminum hydroxide, or phosphate ester, Phosphorus flame retardants such as red phosphorus can be mentioned, but when heat resistance is required, melamine cyanurate and magnesium hydroxide are preferable.

  In the above detailed description, the present invention has been described mainly with respect to characteristic parts so that the present invention can be more easily understood. However, the present invention is not limited to the embodiments described in the above detailed description, and other implementations are possible. It can also be applied to forms and its scope should be interpreted as widely as possible.

  The terms and terminology used in the present specification are used to accurately describe the present invention, and are not used to limit the interpretation of the present invention. Moreover, it would be easy for those skilled in the art to infer other configurations, systems, methods, and the like included in the concept of the present invention from the concept of the invention described in this specification. Accordingly, the description of the claims should be regarded as including an equivalent configuration without departing from the technical idea of the present invention. In addition, in order to fully understand the object of the present invention and the effects of the present invention, it is desirable to fully consider the literatures already disclosed.

DESCRIPTION OF SYMBOLS 1 Liquid sensing sheet 2 Protective sheet 3 Conductive sheet 4 Insulating sheet 5 Conductive sheet 6 Protective sheet 7 Adhesive 8 Adhesive 21 Passing hole 31 Through part 51 Through part 61 Passing hole 101 Liquid sensing sheet

Claims (12)

An insulating sheet with a liquid-permeable structure that exhibits electrical conductivity by liquid;
A conductive sheet bonded to both sides of the insulating sheet;
At least one of the conductive sheets has a penetrating portion that allows the liquid to pass through,
The insulating sheet and the conductive sheet are joined together by an adhesive distributed and disposed on the entire joining surface,
The liquid sensing sheet, wherein the adhesive is partially disposed on a surface of the conductive sheet.   The liquid sensing sheet according to claim 1, wherein the conductive sheet is a metal layer.   The liquid sensing sheet according to claim 2, wherein the metal layer is a metal foil. Having a protective sheet disposed on the surface opposite to the insulating sheet in the conductive sheet having the penetrating portion;
The protective sheet has a through hole that overlaps the penetrating portion of the adjacent conductive sheet,
The liquid sensing sheet according to claim 2, wherein the conductive sheet is formed by applying a conductive paste to the protective sheet.   The liquid sensing sheet according to claim 1, wherein the penetrating portion is at least one of a hole and a slit. Both of the conductive sheets have the penetrating part,
6. The liquid sensing sheet according to claim 1, wherein the penetrating portions of one conductive sheet and the other conductive sheet are disposed so as not to overlap each other.   7. The surface-active agent having surface activity with respect to the liquid is attached to at least a part of the contact portion with the liquid in the penetrating portion of the conductive sheet. The liquid sensing sheet according to any one of the above.   The liquid sensing sheet according to claim 1, wherein the insulating sheet is a nonwoven fabric.   The liquid sensing sheet according to claim 1, wherein the insulating sheet is lyophilic with respect to the liquid.   10. The surfactant according to claim 9, wherein a surfactant having a surface activity with respect to the liquid is attached to at least a part of a contact portion with the liquid in the liquid-permeable structure. Liquid sensing sheet.   11. The liquid sensing sheet according to claim 1, wherein the insulating sheet includes a coloring member whose color is changed by the liquid. Having a protective sheet disposed on the surface opposite to the insulating sheet in the conductive sheet having the penetrating portion;
The protective sheet, a liquid-sensing sheet according to any one of claims 1 to 3, 5 to 11, characterized in that it has a passing hole which overlaps with the through portion of the conductive sheet adjacent.