JP2013191551A - Planar heating element, manufacturing method therefor, and electrode for planar heating element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar heating element in which increase in electrical resistance due to poor contact with the conductive fiber of a heating part can be minimized.SOLUTION: In the planar heating element formed of a heating part that is formed of a fiber structure containing conductive fibers, and an electrode for electrifying the heating part, the electrode is formed of a conductive agent and a binder component. The electrode has a layer shape, and at least a part of which may be impregnated with the fiber structure of the heating part. The electrode may have a curved strip shape. The binder component may be a cured resin (especially, curable polyester resin). The conductive agent may contain metal particles. The electrode may further contain a metal wire. The conductive fiber may contain a carbon-based conductive agent (especially, carbon nanotube).

Description

  The present invention relates to a planar heating element having a heating part formed of a fiber structure containing conductive fibers, a manufacturing method thereof, and an electrode for the planar heating element.

  Conventionally, a large number of planar heating elements by energization have been commercialized and have a wide variety of uses. For example, floor heating, wall heating, snow melting devices, anti-freezing devices, anti-condensation and anti-fogging devices, hot carpets, vehicle seats, horticultural mats, cold jackets and cold rugs have been commercialized. Among them, the fabric-like heating element is particularly widely used because of its excellent flexibility.

  As the fabric heating element, a heating element in which an electric wire (such as a nichrome wire or carbon fiber) that generates heat when energized is attached to a cloth such as felt by sewing is common. On the other hand, as a fabric-like heating element, a planar heating element has also been proposed in which conductive fibers are used as the fibers constituting the cloth and the conductive fibers are energized with electrodes to generate heat.

  Japanese Patent Application Laid-Open No. 2006-328747 (Patent Document 1) discloses two electrodes arranged in parallel on the left and right ends, and conductive wefts that are interposed between these electrodes and in which a conductive paint is applied to the fibers. And a heating element for embedding provided with a plain woven fabric formed of non-conductive warp extending substantially parallel to the electrode.

  In Japanese Patent Laid-Open No. 9-326291 (Patent Document 2), synthetic resin heating yarns are arranged so that a plurality of electrode yarns converge and intersect with a plurality of electrode portions arranged at a predetermined interval. And a planar heating element including a woven fabric in which a synthetic fiber having a large electric resistance is woven between synthetic resin heating yarns. This document describes an electrode yarn in which a copper foil tape in which a polyester multifilament is tin-plated on a core yarn is covered as an electrode yarn, and a conductive resin in which conductive particles such as carbon particles are dispersed as a synthetic resin heating yarn. Synthetic resin heating yarns coated with are described.

  In heating elements made of these fabrics, a method is usually adopted in which an electrode thread such as a fine metal wire is woven as an electrode in a direction orthogonal to the conductive thread, the conductive thread is brought into contact with the electrode thread, and the conductive thread is energized from the electrode. Has been. In this method, if the conductive yarn is arranged on the weft, the electrode yarn is arranged on at least a part of the warp, and if the conductive yarn is arranged on the warp, the electrode yarn is arranged on at least a part of the weft. The conductive fiber and the electrode yarn are energized by being brought into contact with each other at right angles.

  However, in this method, it is difficult to sufficiently contact the conductive fiber and the electrode yarn, and electrical resistance is generated due to poor contact, and heat is easily generated at the electrode portion. In addition, since the electrode yarn is woven into the fiber structure, it is difficult to form the pattern shape of the electrode yarn in a curved shape. Furthermore, in the case of electrode yarns such as fine metal wires, there is a concern of disconnection due to repeated bending. Therefore, a planar heating element using these is not suitable for applications that require repeated bending.

  Furthermore, in recent years, a planar heating element has also been proposed in which a woven fabric is prepared using conductive fibers obtained by coating a carbon nanotube as a conductor on the fiber surface, and an electrode is attached to the fabric to energize the fabric.

  Japanese Patent Application Laid-Open No. 2010-192218 (Patent Document 3) discloses a sheet heating element composed of a heat generating portion formed of a knitted fabric containing conductive fibers and an electrode portion for energizing the heat generating portion. And the planar heating element in which the said electroconductive fiber contains an organic fiber and the carbon nanotube which coat | covers the surface of this organic fiber is disclosed. This document describes a method of sticking a strip electrode portion to a fabric with a conductive adhesive as an electrode, and a metal foil having a conductive adhesive layer is exemplified as the strip electrode portion having a conductive adhesive. .

  However, since the planar heating element includes organic fibers that are non-conductive fibers, the electrical resistance due to poor contact between the conductive fibers and the electrodes due to the interposition of the organic fibers, such as portions where the organic fibers are exposed on the surface. It increases, and heat is likely to be generated at the electrode part. Further, the adhesive force between the belt-like electrode portion and the heat generating portion is not sufficient, and peeling or misalignment tends to occur. Furthermore, since the strip electrode portion is formed of a metal foil, the pattern shape of the electrode cannot be easily controlled, and the bending resistance is low.

JP 2006-328747 A (Claim 1, paragraphs [0017] [0018], FIG. 2) JP-A-9-326291 (Claim 1, paragraph [0013], Example) JP 2010-192218 A (Claim 1, paragraphs [0104] [0105], Examples)

  Accordingly, an object of the present invention is to provide a planar heating element, a method for manufacturing the same, and an electrode for the planar heating element that can suppress an increase in electrical resistance due to poor contact of the heating part with the conductive fibers.

  Another object of the present invention is to provide a sheet heating element, a manufacturing method thereof, and an electrode for sheet heating element that have both flexibility and bending resistance and can be firmly bonded to a heating portion.

  Still another object of the present invention is to provide an electrode for a planar heating element that can easily form a desired pattern shape such as a curved shape, a manufacturing method thereof, and a planar heating element including the electrode.

  Another object of the present invention is to provide a planar heating element capable of generating heat with a predetermined temperature distribution pattern, a method for manufacturing the same, and an electrode for the planar heating element.

  As a result of intensive studies, the inventors of the present invention have formed an electrode part of a planar heating element including a heating part formed of a fiber structure containing conductive fibers with a conductive agent and a binder component, thereby The inventors have found that an increase in electrical resistance due to poor contact with conductive fibers can be suppressed, and have completed the present invention.

  That is, the planar heating element of the present invention is a planar heating element formed by a heating part formed of a fiber structure containing conductive fibers and an electrode part for energizing the heating part, The electrode part includes a conductive agent and a binder component (adhesive resin). The electrode part may be layered, and at least a part (at least a part of the conductive agent) may be impregnated in the fiber structure of the heat generating part. The planar shape of the electrode part may be a curved line or a band. The fiber structure may be a woven fabric. The fiber structure further includes non-conductive fibers, and the conductive fibers may be included in any one of the warp and the weft. The planar heating element of the present invention may have a plurality of linear or strip electrode portions extending in a direction intersecting with the conductive fibers. The distance between the strip electrode portions may be uniform in the length direction of the electrode portions, or may be non-uniform (or changed). The binder component may be a curable resin (particularly a curable polyester resin). The conductive agent may contain metal particles. The conductive agent may contain carbonaceous particles. The electrode portion may further include a metal wire. The conductive fiber may contain a carbon-based conductive agent (particularly carbon nanotube). The electrode part is a laminate formed of a first layer containing a metal-based conductive agent and a binder component, and a second layer stacked on the first layer and containing a carbon-based conductive agent and a binder component. In particular, the first layer may be disposed on the surface side.

  The present invention also includes a method for manufacturing the planar heating element, which includes a coating process in which a conductive paste containing a conductive agent and a binder component is applied to the surface of the heat generating portion. This manufacturing method may further include a curing step of curing the applied conductive paste. In the application step, the conductive paste may be applied by screen printing.

  In the present invention, there is provided an electrode used for an electrode part of a planar heating element formed by a heating part formed of a fiber structure containing conductive fibers and an electrode part for energizing the heating part. In addition, an electrode for a planar heating element formed of a conductive agent and an adhesive resin is also included.

  In this invention, since the electrode part of the planar heating element provided with the heat generating part formed of the fiber structure containing the conductive fiber is formed of the conductive agent and the binder component, the contact efficiency of the heat generating part with respect to the conductive fiber. And increase in electrical resistance due to poor contact can be suppressed. In particular, by forming the binder component with a curable polyester resin, the binder component has both flexibility and bending resistance, and can be firmly bonded to the heat generating portion. Moreover, by forming with a conductive agent and a binder component, it is possible to easily form a desired pattern shape such as a curved shape as compared with a conventional electrode woven with a metal wire or an electrode formed with a metal foil. Furthermore, by forming a planar heating element with such electrodes and making the distance between the electrode parts nonuniform (or changing) in the length direction of the electrode parts, heat is generated with a predetermined temperature distribution pattern. it can.

FIG. 1 is a surface photograph of the planar heating element obtained in Example 3. FIG. 2 is a heat distribution diagram by thermography showing the heat generation state of the planar heating element obtained in Example 3. FIG. 3 is a surface photograph of the planar heating element obtained in Example 4. FIG. 4 is a heat distribution diagram by thermography showing the heat generation state of the sheet heating element obtained in Example 4. FIG. 5 is a surface photograph of the planar heating element obtained in Example 5. FIG. 6 is a heat distribution diagram by thermography showing the heat generation state of the sheet heating element obtained in Example 5. FIG. 7 is a surface photograph of the planar heating element obtained in Example 7. FIG. 8 is a heat distribution diagram by thermography showing the heat generation state of the sheet heating element obtained in Example 7. FIG. 9 is a heat distribution diagram by thermography showing the heat generation state of the sheet heating element obtained in Comparative Example 2. FIG. 10 is a graph showing the heat generation distribution of the planar heating element obtained in Comparative Example 2. FIG. 11 is a heat distribution diagram by thermography showing the heat generation state of the sheet heating element obtained in Example 8. FIG. 12 is a graph showing the heat generation distribution of the planar heating element obtained in Example 8.

[Electrode part]
The planar heating element of the present invention is formed of a heating part formed of a fiber structure containing conductive fibers and an electrode part for energizing the heating part. The electrode portion (surface heating element electrode) includes a conductive agent and a binder component (or adhesive resin).

(Conductive agent)
The conductive agent includes an inorganic conductive agent and an organic conductive agent.

  Examples of the inorganic conductive agent include carbons (for example, carbon black such as furnace black, acetylene black, ketjen black, artificial graphite, expanded graphite, natural graphite, carbon nanotube, fullerene, etc.), simple metals or alloys (for example, Silver, gold, copper, chromium, nickel, iron, magnesium, aluminum, platinum, zinc, manganese, tungsten, stainless steel, etc.), metal compounds or ceramics (for example, copper sulfide, ferrite, tourmaline, diatomaceous earth, etc.) It is done. These inorganic conductive agents can be used alone or in combination of two or more. For example, a carbon-based conductive agent and a metal-based conductive agent may be combined. Further, it may be a composite, and may be, for example, an organic or inorganic compound (such as silver-coated copper) obtained by plating or vapor-depositing the metal alone, or a ceramic carrying carbon black or graphite. Furthermore, the composite may be a composite with a non-conductive agent.

  Examples of organic conductive agents include conductive polymers such as polyacetylene-based resins (for example, polyacetylene), polythiophene-based polymers (for example, polythiophene), polyphenylene-based polymers (for example, polyparaphenylene), and polypyrrole-based materials. Examples thereof include conductive polymers such as a polymer (eg, polypyrrole), a polyaniline polymer (eg, polyaniline), and a polyester resin modified with an acrylic polymer. These organic conductive agents can be used alone or in combination of two or more.

  Of these conductive agents, inorganic conductive agents are preferred from the viewpoint of conductivity. Further, among inorganic conductive agents, metal conductive agents containing metals such as silver, gold, copper, and aluminum, and carbon conductive agents such as carbon black and carbon nanotubes are widely used. Further, from the viewpoint of conductivity, it is preferable to contain a metal-based conductive agent (particularly metal particles), and a silver-based conductive agent (for example, silver alone, silver coat or plated copper) is particularly preferable. Moreover, it is preferable that a carbon-type electrically conductive agent is included from the point which is excellent in durability or corrosion resistance, and carbonaceous particles, such as carbon black and a carbon nanotube, are especially preferable.

  Examples of the shape of the conductive agent include particulate (powder), plate (or scale), fiber, and indefinite shape. Of these shapes, particle shapes such as approximately spherical and polygonal shapes, fiber shapes, etc. are widely used, entering the inter-fiber voids of the fiber structure constituting the heat generating part, and suppressing poor contact between conductive fibers and electrodes From the point which can do, a particulate form is preferable.

  The average particle diameter of the conductive agent (in the case of an anisotropic shape such as carbon nanotube, the average diameter of the long diameter and the short diameter) can be appropriately selected from the range of about 10 nm to 100 μm, and the mechanical characteristics and conductivity of the electrode From 0.3 to 80 μm, preferably 0.5 to 50 μm, more preferably about 1 to 40 μm (particularly 3 to 50 μm), and in the case of a carbon-based conductive agent (carbonaceous particles), for example, 10 to 500 nm, preferably 20 to 300 nm, more preferably about 30 to 100 nm (particularly 40 to 80 nm).

(Binder component)
In the present invention, the electrode portion is formed of the conductive agent and the binder component, and unlike the electrode formed of a metal wire or a metal foil, the electrode itself has flexibility, so that the interfibers of the fiber structure (For example, in a woven fabric, a binder component containing a conductive agent (especially before curing) between adjacent yarns, a gap between intersections of warp and weft, or between single fibers when warp and weft are multifilament yarns) The binder component) can penetrate, and poor contact between the conductive fiber and the electrode contained in the fiber structure constituting the heat generating portion can be suppressed. Therefore, even if the fiber structure contains non-conductive fibers, the binder component is filled following the shape of the non-conductive fibers, or when the non-conductive fibers are multifilament yarns, the gaps between the single fibers This is because the binder component penetrates into the electrode, so that the contact efficiency between the electrode and the conductive fiber can be improved, and both can be contacted uniformly.

  As the binder component, a conventional adhesive or pressure-sensitive adhesive can be used, but an adhesive is preferable from the viewpoint that the conductive agent can be firmly fixed to the fiber structure of the heat generating portion.

  For adhesives, conventional adhesives, thermoplastic resins (polyolefin resins, acrylic resins, vinyl acetate resins, styrene resins, polyester resins, polyamide resins, thermoplastic polyurethane resins, etc.), curable resins (Curable acrylic resin, curable polyester resin, vinyl ester resin, epoxy resin, melamine resin, urea resin, phenol resin, silicone resin, polyimide resin, urethane resin, etc.), rubber or thermoplastic elastomer Etc. These adhesives can be used individually or in combination of 2 or more types.

  Among these adhesives, curable resins such as curable acrylic resins, curable polyester resins, and urethane resins can be heated or heated because they can be firmly bonded and integrated with the fiber structure of the heat generating portion. A cured resin cured with light (especially a cured resin obtained by curing a thermosetting resin) is preferable, and it is possible to achieve both adhesiveness, flexibility, and bending resistance in combination with the fiber structure. Is particularly preferred.

The curable polyester resin includes unsaturated polyester and copolymer polyester. Unsaturated polyesters are excellent in flexibility and flex resistance, and as a dicarboxylic acid component, in addition to polymerizable dicarboxylic acid components (ignored maleic acid, maleic acid, fumaric acid, etc.), C such as adipic acid and sebacic acid. Unsaturated polyester containing _6-16 aliphatic dicarboxylic acid; long chain alkanediol (such as C _4-10 alkanediol such as butanediol) or polyalkylene glycol (diethylene glycol, dipropylene glycol, polytetramethylene glycol, etc.) as the diol component The unsaturated polyester containing a long-chain diol component such as); an unsaturated polyester containing the aliphatic dicarboxylic acid component and the long-chain diol component may be used. The copolyester may also contain units of the aliphatic dicarboxylic acid component and the long-chain diol component in addition to C _2-4 alkylene C _6-14 arylate units such as ethylene terephthalate and butylene terephthalate, and further curing. It may contain a monomer unit having a reactive group (for example, a hydroxyl group, a carboxyl group, an amino group, etc.) with respect to the agent. The curing agent may be, for example, an isocyanate curing agent, an amine curing agent, an acid anhydride curing agent, an imidazole curing agent (particularly an isocyanate curing agent such as polyisocyanate), and the like.

  The ratio of the binder component can be selected from the range of about 1 to 100 parts by mass with respect to 100 parts by mass of the conductive agent, for example, 3 to 80 parts by mass, preferably 5 to 60 parts by mass, and more preferably 10 to 50 parts by mass. It may be about (especially 10 to 40 parts by mass). When the ratio of the binder component is too large, the conductivity is lowered, and when it is too small, the adhesiveness is lowered. The conductive agent is preferably uniformly dispersed in the binder component at such a ratio (concentration).

(Other additives)
In the electrode section, further conventional additives such as stabilizers (heat stabilizers such as copper compounds, ultraviolet absorbers, light stabilizers, antioxidants), dispersants, fine particles, colorants, antistatic agents, A flame retardant, a plasticizer, a lubricant, a crystallization rate retarder, and the like may be contained. These additives can be used alone or in combination of two or more. These additives may be carried on the surface of the molded body or may be contained in the fiber.

(Metal wire)
The electrode part may be formed of only a conductive agent and a binder component (additive as required), but may further include a metal wire in order to improve conductivity. In the present invention, even when a metal wire is used, since the conductivity and the binder component are closely interposed between the metal wire and the conductive fiber of the heat generating portion, the contact failure between the electrode and the conductive fiber is suppressed. it can.

  The metal wire should just have the metal simple substance or alloy illustrated by the term of the said electrically conductive agent on the surface. Among the simple metals and alloys, metals such as chromium, nickel, copper, silver, gold, and aluminum are generally used from the viewpoint of conductivity.

  The metal wire may be a covering yarn obtained by covering a synthetic fiber (such as polyester fiber or polyamide fiber) with a thin metal wire from the viewpoint of knitting property. The average diameter of the fine metal wires is, for example, about 1 to 500 μm, preferably 5 to 300 μm, more preferably 10 to 100 μm (particularly 20 to 50 μm). The average fineness of the synthetic fiber is, for example, about 20 to 500 dtex, preferably about 30 to 300 dtex, and more preferably about 50 to 200 dtex. A plurality of metal wires may be disposed on one electrode, for example, 2 to 100, preferably 5 to 50, and more preferably about 10 to 30.

  When the fiber structure of the heat generating portion is a knitted fabric, the metal wire may be incorporated as a part of the constituent yarn of the knitted fabric. A plurality of metal wires may be introduced in each electrode, and may be, for example, about 2 to 100, preferably 3 to 50, more preferably about 5 to 30 (especially 10 to 20).

  The metal wire can be used depending on the application and is effective in applications that require high heat generation, but in applications that require flexibility and in applications where the electrode shape is formed in a curved line or strip, the metal wire It is preferable to form an electrode with a conductive agent and a binder component alone without combining with a wire.

(Shape of electrode part)
The shape (surface shape) of the electrode part (or electrode) can be appropriately selected according to the shape of the heat generating part, and is not particularly limited, and may be linear, but usually both ends of the heat generating part that is a rectangular sheet. Since it is disposed in the part, it has a strip shape (or narrow width). Furthermore, since the electrode part is formed through a coating process as will be described later, it is formed in layers on the surface of the heating element, and at least a part of the layered electrode part (particularly, at least a part of the conductive agent) It is preferable that the fiber structure is impregnated (or penetrated or penetrated). By impregnating (filling) the inside of the fiber structure with the electrode part, the electrode part and the conductive fiber can be contacted uniformly, and contact failure can be suppressed.

  The electrode part may have a laminated structure, and may be a laminated body with a second layer containing a second conductive agent and a binder component. From the viewpoint of economic efficiency, for example, the laminate includes a first layer containing a metallic conductive agent such as silver particles and a binder component, and a second layer containing a carbon conductive agent such as carbon black and a binder component. The laminated body may be sufficient.

  The order of lamination is not particularly limited, and any of the first layer and the second layer may be an inner layer (layer on the side in contact with the fiber structure containing conductive fibers). From the point that durability (corrosion resistance) can be improved by protecting the highly conductive first layer, the second layer containing a carbon-based conductive agent and a binder component may be used as a surface layer, and the conductivity is high and large. The first layer containing the metal-based conductive agent and the binder component may be used as the surface layer because a metal-based conductive agent for passing an electric current can be unevenly distributed on the surface layer to improve the conductivity. In particular, when the conductive fiber is formed of a conductive agent including a carbon-based conductive agent, the conductive fiber including the carbon-based conductive agent is formed by setting the second layer including the carbon-based conductive agent and the binder component as an inner layer. The second layer with high affinity to the fiber structure (in the case of woven fabric, the intersection of warp and weft, etc.) is impregnated, and the metal conductive agent for high current flow is unevenly distributed on the surface layer. It is possible to improve the electrical conductivity. Further, in the structure in which the second layer is an inner layer, the first layer has a three-layer structure in which a third layer containing a carbon-based conductive agent and a binder component is further laminated as a surface layer on the first layer. May be protected.

  The thickness ratio between the first layer containing the metal-based conductive agent and the binder component and the second layer containing the carbon-based conductive agent and the binder component can be appropriately selected according to the ratio of the conductive agent, but the coating amount (solid For example, the ratio of the first weight / the second weight is 200/1 to 0.2 / 1, preferably about 50/1 to 0.5 / 1. If the thickness of the first layer is too thin, it becomes difficult to flow a large current, whereas if the thickness of the second layer is too thin, the contact efficiency from the heat generating portion to the first layer is reduced. In either case, the conductivity decreases.

  When the electrode includes a metal wire, it is sufficient that the conductive agent and the metal wire are in contact with each other. For example, the metal electrode may be included in the layered electrode portion, and the metal wire is formed below the layered electrode portion. It may be in close contact. Furthermore, as the conductive agent combined with the metal wire, a metal-based conductive agent and a carbon-based conductive agent are widely used, and the conductive agent may be a metal-based conductive agent because it can improve conductivity. A carbon-based conductive agent may be used, and a carbon-based conductive agent is particularly preferable from the viewpoint of excellent balance between conductivity and surface protection.

  The linear or belt-like electrode portion only needs to extend in a direction intersecting with the conductive fibers of the heat generating portion. For example, in a heating element in which the heat generating portion is formed of a woven fabric using conductive fibers for wefts, You may form so that the length direction of a strip | belt-shaped electrode part may become parallel to a direction.

  Furthermore, when the electrode part is formed of a conductive agent and a binder component alone without being combined with a metal wire, the electrode part can be easily formed into a desired shape by coating, so the pattern shape on the surface of the heating element is curved. Alternatively, it may be formed in a bent band shape. Therefore, it is easy to combine a straight belt shape and / or a curved belt shape to form a pattern and impart design properties to the shape of the electrode.

  The electrode part may be formed with a plurality of electrode parts including at least a pair of electrode parts for energizing the heat generating part. In the present invention, by utilizing the property that the amount of heat generated on the heat generating surface of the heat generating element is inversely proportional to the distance between the electrode parts, the heat generating elements having different distributions of heat generation are controlled by controlling the distance between the pair of strip electrode parts. Can be produced. Specifically, the heating element (heat generation amount) that can generate heat substantially uniformly on the entire heating surface by arranging the distance between the strip electrode parts uniformly in the length direction of the electrode parts, that is, by arranging both electrode parts in parallel. Can be prepared). On the other hand, the distance between the strip electrode portions is arranged non-uniformly (changed) in the length direction of the electrode portions, for example, straight strip electrode portions are arranged in one direction (the direction in which the electrodes extend). It is arranged in a form that expands (or narrows) as it goes toward (for example, a substantially C-shaped form), or the distance between the other electrode with respect to a pair of electrodes as it goes in one direction (the direction in which the electrode extends) It is arranged in a form that is small at one end, large at the middle part, and small at the other end (for example, a substantially C-shaped form in which a curved strip electrode portion and a straight strip electrode portion are combined). Thus, a heating element that can generate heat unevenly on the heating surface (a heating element having a non-uniform distribution of heat generation and a gradient structure in the distribution of heat generation) can be prepared, for example, arranged in a substantially C-shaped form. Heat generated in the middle There can be prepared heatable heating element was suppressed pattern. Therefore, the form of the pair of electrode portions can be formed by combining various patterns of electrode elements such as a linear shape, a curved shape (including a loop shape and a spiral shape), a bent shape, and a stepped shape.

  The size of the electrode part can be selected according to the shape of the heat generating part. For example, when an electrode part is strip | belt shape, an average width can be selected according to the size of a heat-emitting part, for example, 1-100 mm, Preferably it is 2-50 mm, More preferably, it may be about 3-30 mm.

[Heat generation part]
The heat generating part is formed of a fiber structure including conductive fibers.

(Conductive fiber)
Conventional conductive fibers can be used as the conductive fibers, but conductive fibers formed of organic fibers and a conductive agent are preferable from the viewpoint of flexibility suitable for knitting.

  Organic fibers are used to impart flexibility and flexibility to the heat generating part, such as non-synthetic fibers [for example, natural fibers (cotton, hemp, wool, silk, etc.), regenerated fibers (rayon, cupra, etc.), half Synthetic fibers (such as acetate fibers)] may be used, but it is preferable to include at least synthetic fibers from the viewpoint of adhesion to a conductive agent.

  Examples of the synthetic fiber include polyester fiber, polyamide fiber, polyolefin fiber, acrylic fiber, polyurethane fiber, polyvinyl alcohol fiber, polyvinylidene chloride fiber, and polyvinyl chloride fiber. These synthetic resins can be used alone or in combination of two or more.

  When the synthetic fiber is formed of two or more types of polymers, it may be a mixed spun fiber formed from a mixture (alloy resin) of two or more types of polymers, or two or more types of polymers. May be a composite spun fiber in which a plurality of phase separation structures are formed. Furthermore, a phase separation structure may be formed depending on the presence or absence of a conductive agent. Examples of the composite spun fiber include a sea-island structure, a core-sheath structure, a side-by-side laminated structure, a structure in which a sea-island structure and a core-sheath structure are combined, and a structure in which a side-by-side laminated structure and a sea-island structure are combined. It is done. In the composite spun fiber in which the phase separation structure is formed by the presence or absence of the conductive agent, the phase containing the conductive agent is arranged on the surface.

Among these synthetic fibers, polyester fibers (especially poly C _2-4 alkylene such as polyethylene terephthalate and polybutylene terephthalate, etc.) have good adhesion to the conductive agent and excellent bending fatigue resistance and thermal characteristics. Terephthalate fibers) and polyamide resins (especially aliphatic polyamide fibers such as polyamide 6 and polyamide 66) are preferred, and polyester fibers are more preferred from the viewpoint of good thermal stability and dimensional stability.

  The cross-sectional shape of the organic fiber is not particularly limited, and may be a normal organic fiber having a round cross section or an organic fiber having an irregular cross section other than a round cross section. In the case of a modified cross-section fiber, the cross-sectional shape thereof is any of, for example, a square, a polygon, a triangle, a hollow, a flat, a multi-leaf or star, a dogbone, a T-shape, a V-shape, etc. Also good. Of these shapes, a round cross-section is widely used, but an irregular cross-sectional shape may be used in order to improve the adhesion of the conductive agent. As an irregular cross-sectional shape, a cross-sectional shape that has a plurality of (for example, about 2 to 10, preferably about 3 to 6) recesses or grooves extending in the length direction, for example, a multileaf or star shape (for example, 3-6 leaves) is preferred. The multilobal or star shape may be a shape having a plurality of concave portions at symmetrical positions when viewed from the center of the cross section. Such an irregular cross-sectional shape may be the shape of the core portion of the core-sheath type composite spun fiber having a round cross-sectional shape.

  The organic fiber may be any of monofilament yarn, twin yarn, multifilament yarn, processed multifilament yarn, spun yarn, tape yarn, and combinations thereof. In the case of a composite yarn such as a multifilament yarn or a spun yarn, it may be a composite yarn obtained by combining the same organic fibers or a composite yarn obtained by combining different types of organic fibers. Furthermore, in order to obtain the desired fineness, a plurality of multifilament yarns may be combined. What is necessary is just to adjust the number of multifilament yarns according to the target fineness, for example, 5-500, Preferably it is 8-400, More preferably, it is about 10-300.

  The average fineness of organic fibers (total fineness in the case of composite yarns such as multifilament yarns) is not particularly limited, but is selected from the range of 10 to 1000 dtex depending on, for example, the target basis weight, thickness, and flexibility of the planar heating element For example, it is about 30 to 500 dtex, preferably about 50 to 400 dtex, and more preferably about 100 to 300 dtex.

  As the conductive agent, the conductive agent exemplified in the section of the electrode can be used. Among the conductive agents, carbon-based conductive agents such as carbon black and carbon nanotubes are preferable because they are lightweight and flexible, and carbon nanotubes are particularly preferable because high conductivity can be realized without impairing fiber properties. preferable.

  The conductive agent only needs to be present on the surface of the organic fiber. For example, the conductive agent may adhere to the surface of the organic fiber, or the conductive agent may be included in the organic fiber. The surface of the organic fiber may be covered with an area ratio of, for example, 50% or more, preferably 60% or more, more preferably 80% or more (particularly 100%), for example, with a conductive agent or a layer containing a conductive agent. Good.

  The conductive fiber having a conductive agent attached to the surface of the organic fiber is preferably a conductive fiber in which carbon nanotubes are attached or coated on the surface of the organic fiber. For example, JP 2010-59561 A, JP 2010-192218 A. Can be used. The carbon nanotubes may be attached via a binder. Examples of commercially available products include “CNTEC” manufactured by Kuraray Living Co., Ltd.

  The conductive fiber in which the conductive agent is contained in the organic fiber may be a composite fiber having a conductive layer kneaded with the conductive agent in the surface layer, and a core-sheath type composite fiber is preferable. In the core-sheath type composite fiber, the cross-sectional shape of the sheath part may be the multilobal or star shape. In the core-sheath type composite fiber, the cross-sectional shape of the sheath part may be a round cross-sectional shape, and the entire surface (approximately 100%) of the core part surface may be covered with a sheath part containing a conductive agent. Furthermore, it may be a composite fiber in which only a concave portion of a multi-leaf or star-shaped fiber is covered with a layer containing a conductive agent. As such a composite fiber, a composite fiber having a surface layer containing carbon black is preferable. For example, a conductive fiber described in International Publication No. WO2008 / 4448 can be used. Examples of commercially available products include “Kurabobo” manufactured by Kuraray Trading Co., Ltd. and “Shakespeare” manufactured by BASF.

  Among these conductive fibers, the fluctuation of the electric resistance at the time of stretching deformation is small, and since the durability, the bending fatigue resistance, and the flexibility are excellent, the conductive fibers to which carbon nanotubes are attached or coated (particularly, carbon nanotubes are used). Particularly preferred is a conductive fiber in which the containing layer covers substantially the entire surface of the organic fiber.

  The ratio of the conductive agent can be selected from a range of about 0.1 to 100 parts by mass with respect to 100 parts by mass of the organic fiber, for example, 0.1 to 50 parts by mass, preferably 0.5 to 25 parts by mass, and more preferably. Is about 1 to 20 parts by mass (particularly 1 to 15 parts by mass).

The linear electric resistance value at 20 ° C. of the conductive fiber of the conductive fiber is, for example, 1 × 10 ⁰ to 1 × 10 ⁷ Ω / cm (for example, 5 × 10 ⁰ to 1 × 10 ⁶ Ω / cm), preferably It is about 1 × 10 ¹ to 1 × 10 ⁵ Ω / cm, more preferably about 1 × 10 ² to 1 × 10 ⁴ Ω / cm (particularly 1 × 10 ^{3 to} 5 × 10 ³ Ω / cm).

If the linear electric resistance value is too high, the heat generation efficiency is lowered, and the heat generation amount may be insufficient even when arranged in high density with a fabric or the like. For example, in the case of a fiber having a linear electrical resistance of 1 × 10 ⁸ Ω / cm and a fineness of 100 dtex, even if an ordinary woven method is used and the density is 90 pieces / inch and an applied voltage of 200 V is applied at intervals of 3 cm, 16 W / Only a calorific value of m ² is generated, which is not practical.

On the other hand, if the linear electric resistance value is too low, the heat generation efficiency is too high, and if it is arranged in high density with a fabric or the like, the heat generation amount may be too high. For example, in the case of a fiber of 100 dtex with a linear electrical resistance of 0.1 Ω / cm, when a density of 90 pieces / inch is applied using a normal woven technique and an applied voltage of 5 V is applied at intervals of 100 cm, about 9000 W / m becomes ^two of the calorific value, the current flowing through the heating fabric of 1m ² will be 1800 amps, not a realistic product.

(Fiber structure)
The heat generating part is formed of a fiber structure including the conductive fiber. Examples of the fiber structure include woven fabric, knitted fabric, nonwoven fabric, lace fabric, and net. Of these, woven fabrics (woven fabrics), knitted fabrics (knitted fabrics), and non-woven fabrics are preferable from the viewpoint of heat generation efficiency and the like, and woven fabrics and knitted fabrics (particularly woven fabrics) from the point that uniform heat generation is possible and short circuit can be suppressed. Is preferred.

  Examples of the woven fabric include conventional woven fabric (woven fabric or woven fabric), for example, plain weave such as taffeta weave, twill weave or oblique weave (twill weave), satin weave, and pile weave. Among these woven fabrics, twill weave and plain weave are preferable because a high-density structure can be formed and heat generation efficiency is easily improved.

  Examples of the knitted fabric include a conventional knitted fabric (knitted fabric or knitted fabric), for example, a flat knitted fabric (tenji knitted fabric), a warp knitted fabric, a circular knitted fabric, a horizontal knitted fabric, a double knitted fabric, a rubber knitted fabric, and a pile knitted fabric.

  Furthermore, the fiber structure should just contain electroconductive fiber at least, and the ratio of electroconductive fiber is 1 mass% or more (for example, 1-100 mass%) with respect to the whole fiber structure, for example. The amount is preferably about 10 to 100% by mass (for example, 20 to 90% by mass), more preferably about 30 to 100% by mass (for example, 40 to 80% by mass).

  When forming a fiber structure by combining conductive fibers and non-conductive fibers, as the non-conductive fibers, organic fibers constituting the conductive fibers can be used, among which polyester fibers, polyamide fibers, Polyolefin fibers are preferred, and polyester fibers are particularly preferred. As for the non-conductive fibers, the cross-sectional shape and type, and the single filament fineness, the number of yarns, the number of twists in the multifilament yarn and the spun yarn, the same fibers as the conductive fibers can be used. In addition, when using a nonelectroconductive fiber as a warp of a textile fabric, the fineness of the weft comprised with the conductive fiber is 0.5-2 times with respect to the fineness of a warp, Preferably it is 1-1. The fineness may be about 8 times, more preferably about 1.2 to 1.5 times.

The weight per unit area (weight per unit area) of the fiber structure is, for example, 10 to 300 g / m ² , preferably 30 to 250 g / m ² , more preferably 50 to 200 g / m ² from the viewpoint of heat generation efficiency. Degree. By setting the basis weight within this range, it is possible to form a power generation unit that is lightweight, thin and flexible and has high power generation efficiency.

  The thickness of the fiber structure is, for example, about 0.1 to 1 mm, preferably about 0.15 to 0.8 mm, and more preferably about 0.2 to 0.6 mm.

  Furthermore, in the case of a woven fabric, all or part of warp and / or weft may be composed of conductive fibers. In particular, by configuring either warp or weft with conductive fibers, heat generation efficiency can be easily controlled by adjusting the number of driven yarns, and contact of conductive fibers can be reduced by a simple method, and heat spots can be suppressed. This is preferable. Furthermore, in order to improve the heat generation efficiency, the yarn density (the number of driven-in yarns) may be adjusted. For example, when a non-conductive fiber of 150 to 200 dtex is used for the warp and a conductive fiber of 150 to 250 dtex is used for the weft, the weft density is, for example, about 50 to 100 / inch, preferably about 55 to 80 / inch. Also good. When a woven fabric is formed with such a yarn density and conductive fibers are used as wefts or warps, the heat generation efficiency can be effectively improved. Further, when conductive fibers are used for either one of the weft and the warp, various heater shapes which are one of the objects of the present invention can be obtained by devising the arrangement of the electrodes. Furthermore, it is particularly preferable that conductive fibers are used as the wefts and nonconductive fibers are used as the warp yarns since the dropping of the conductive agent is suppressed.

  The surface of the heating element may be covered or covered with a cover member or the like. The cover member may be formed of a soft heat-resistant resin such as polyester, polyamide, or polyurethane.

[Method for manufacturing sheet heating element]
The planar heating element of the present invention can be obtained by a manufacturing method including an application process in which a conductive paste containing a conductive agent and a binder component is applied to the surface of a heating part.

  The conductive paste only needs to contain a conductive agent and a binder component constituting the electrode, but it is dissolved or dispersed in a solvent from the viewpoint of improving the coatability and sufficiently impregnating the electrode between the fiber structure fibers. It is preferable.

  The solvent can be selected according to the type of the binder. For example, alcohols (ethanol, isopropanol, etc.), ketones (acetone, methyl ethyl ketone, etc.), ethers (tetrahydrofuran, etc.), aliphatic hydrocarbons (hexane, etc.), Alicyclic hydrocarbons (such as cyclohexane), aromatic hydrocarbons (such as toluene and xylene), halogenated carbons (such as dichloromethane), esters (such as methyl acetate), water, cellosolves (methyl cellosolve, ethyl cellosolve) Etc.), cellosolve acetates (such as butyl cellosolve acetate), sulfoxides (such as dimethylsulfoxide), amides (such as dimethylformamide) and the like. These solvents can be used alone or in combination of two or more.

  The ratio of the solvent can be selected from the range of about 0 to 200 parts by mass with respect to 100 parts by mass of the conductive agent, for example, 5 to 100 parts by mass, preferably 10 to 80 parts by mass, and more preferably about 20 to 60 parts by mass. It is. The solid content concentration of the paste is, for example, about 20 to 90% by mass, preferably about 30 to 80% by mass, and more preferably about 40 to 75% by mass (particularly about 45 to 70% by mass). If the proportion of the solvent is too large, it will be difficult to produce a highly conductive electrode part. Conversely, if the amount is too small, a sufficient amount of conductive agent and binder component will penetrate into the gaps in the fiber structure of the heat generating part. It becomes difficult. That is, if the solid content concentration is too high, the viscosity of the paste is too high, or it is difficult for the conductive agent and the binder component to enter the fiber structure (particularly between the fibers of the multifilament yarn). It is difficult to ensure the amount of the conductive agent and binder component supported on the structure.

  As a method for applying the conductive paste, for example, a screen printing method, a dispense coating method, a gravure printing method, a gravure offset printing method, an offset printing method, an ink jet printing method, or the like can be used. Among these methods, the screen printing method is preferable because an appropriate pressure can be applied to the thick coating film for impregnating the inside of the fiber structure with the conductive paste. That is, in the screen printing method, the ink is pushed out through the holes in the screen plate while rolling the ink with a squeegee, so that the conductive paste can be impregnated in a clear pattern shape inside the fiber structure.

Coating amount can be selected depending on the thickness of the planar heating element, for example, 5 to 100 mg / cm ^2, preferably 10 to 50 mg / cm ^2, more preferably 20-40 mg / cm ² (particularly 25~35mg / Cm ² ). If the coating amount is too small, a necessary conductive agent cannot be applied to the electrode portion for use as wiring, and abnormal heating of the wiring is likely to occur. On the other hand, if the coating amount is too large, the film thickness increases, so that the flexibility is lowered and the economy is also lowered.

  When the electrode portion includes a metal wire, the metal wire may be fixed to the heat generating portion by a method of sticking using the electrode portion, a method of fixing by sewing, a method of fixing using a fixing tool, etc. A method of incorporating into a part of the fiber structure of the heat generating part is preferable, and for example, a method of weaving as a part of the fabric may be used. For example, in the case of a woven fabric in which the weft is composed of conductive fibers, a method of introducing metal wires as warps at both ends in the weft direction of the fabric may be used. In the case of a knitted fabric in which the warp is composed of conductive fibers, the relationship between the warp direction and the weft direction is reversed.

  When the binder component is a curable resin, a curing step may be included as a subsequent step of the coating step. In the curing step, irradiation with light such as ultraviolet rays or heating may be performed depending on the type of the curable resin, and a curing step in which heat treatment is performed on the thermosetting resin is preferable from the viewpoint of simplicity.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. The evaluation method of the planar heating element in the examples was measured by the following method. In the examples, “parts” and “%” are based on mass unless otherwise specified.

[Evaluation of heat generation behavior and condition and measurement of heat generation distribution]
An AC or DC voltage was applied to two or four strip electrode portions of the obtained heating element, and the amount of heat generated was measured using a general-purpose ammeter. Further, Examples 3 to 6, 8 and Comparative Examples About the heat generating body of 2, heat generation state was confirmed using thermography ("FLIR i5" manufactured by FLIR Systems). Moreover, about the heat generating body of the comparative example 2 and Example 8, the heat_generation | fever distribution was measured.

Example 1
Nylon conductive fiber containing carbon black ("Shakespeare Resistat F901 DO44" manufactured by BASF, nylon monofilament, 48.9 dtex, 10 < ⁵ > [Omega] / cm) is placed on the weft, while polyester processed yarn (Kuraray Trading Co., Ltd., 167 dtex / 48 filament) is placed on the warp, and a copper fine wire with a diameter of 40 μm is used as an electrode on a part of the warp as a polyester processed yarn (Kuraray Trading Co., Ltd., 167 dtex / 48 filament). Sixteen covered covering yarns are continuously introduced to form a belt-like portion, and another covering yarn is introduced to form a belt-like portion at a distance of 20 cm from the 16 introduction portions of the covering yarn. Plain weave with weft density of 60 / inch It was obtained.

The obtained woven fabric was cut by 1 m in the warp direction, and a silver conductive paste (“Dotite FA353N” manufactured by Fujikura Kasei Co., Ltd., paste containing silver particles) was applied at 30 mg / cm ² to the band-shaped portion formed of copper fine wires. After coating by a screen printing method, heat treatment is performed at 150 ° C. for 20 minutes, and two linear strip electrode portions (1 cm width × 15 cm length) are arranged at intervals of 10 cm along the warp direction of the fabric. They were formed in parallel.

When an AC voltage of 100 V was applied to the copper thin wire portions of the two strip electrode portions with respect to the obtained heating element, it showed a uniform heat generation behavior of 44 W (220 W / m ² ) and was about 20 ° C. at room temperature. A uniform heat generation at 40 ° C. was confirmed.

Comparative Example 1
When the AC voltage of 100 V was applied to the two copper thin wire portions on the fabric obtained in Example 1 before coating the conductive paste, 31 W (155 W / m ² ) non-uniform heat generation behavior was observed. Indicated. Abnormal heat generation was also observed in the electrode part of the copper fine wire.

Example 2
Nylon conductive fibers containing carbon black (Kuraray Trading Co., Ltd. “Kurabobo KC-792R B22T4”, 22 dtex, 0.8 × 10 ⁶ Ω / cm) are arranged on the weft. Polyester processed yarn (Kuraray Trading Co., Ltd., 167 dtex / 48 filament) was placed on the warp to obtain a woven fabric with a weft density of 72 yarns / inch in a plain weave structure.

On the obtained woven fabric, a silver conductive paste (“Dotite FA353N” manufactured by Fujikura Kasei Co., Ltd., paste containing silver particles) was applied by a screen printing method at a coating amount of 30 mg / cm ² , and 150 Heat treatment was carried out at 20 ° C. for 20 minutes, and two linear strip electrode portions (1 cm width × 15 cm length) were formed in parallel at 10 cm intervals along the warp direction of the fabric.

When an AC voltage of 100 V was applied to the two places where the silver-based conductive paste was applied to the obtained heating element, it showed a uniform heat generation behavior of 3.8 W (253 W / m ² ), at room temperature of 20 ° C. A uniform heat generation of about 42 ° C. was confirmed below.

Examples 3-5
Polyester conductive fibers coated with carbon nanotubes (“CNTEC240T48” manufactured by Kuraray Living Co., Ltd., 240 dtex, 1500 Ω / cm) are arranged on the weft, and polyester processed yarn (Kuraray Trading Co., Ltd., 167 dtex / 48 filament) is arranged on the warp. Thus, a woven fabric having a weft density of 60 yarns / inch in a plain weave structure was obtained.

Using a silver-based conductive paste (“Dotite FA353N” manufactured by Fujikura Kasei Co., Ltd., paste containing silver particles) in the warp direction on the obtained woven fabric, a coating amount of 30 mg / cm ² is applied by screen printing. After that, heat treatment was performed at 150 ° C. for 20 minutes, and two strip electrode portions having the forms shown in Table 1 were formed in parallel at predetermined intervals along the warp direction of the fabric.

  In Examples 4 and 5, the length of the strip-shaped electrode portion that is curved is the distance between both ends, and in Example 5, the straight strip-shaped electrode portion and the curved strip-shaped electrode portion are: As shown also in FIG. 5 to be described later, they were formed substantially in parallel so that the distances between the opposite ends were equal.

Example 6
Polyester conductive fibers coated with carbon nanotubes (“CNTEC240T48” manufactured by Kuraray Living Co., Ltd., 240 dtex, 1500 Ω / cm) are arranged on the weft, and polyester processed yarn (Kuraray Trading Co., Ltd., 167 dtex / 48 filament) is arranged on the warp. Thus, a woven fabric having a weft density of 60 yarns / inch in a plain weave structure was obtained.

Screen printing is performed on the obtained fabric using a carbon-based conductive paste (“FC-415” manufactured by Fujikura Kasei Co., Ltd., carbon black paste) in the warp direction at a coating amount of 4.5 mg / cm ^2. After coating, drying, and further using a silver conductive paste (“Dotite FA353N” manufactured by Fujikura Kasei Co., Ltd., paste containing silver particles), a screen printing method at a coating amount of 19 mg / cm ² After coating, the film was heat treated at 150 ° C. for 20 minutes to form two strip electrode portions having the forms shown in Table 1 in parallel at predetermined intervals along the warp direction of the fabric.

  About each heat generating body obtained in Examples 3-6, the voltage shown in Table 1 was applied to two places which apply | coated the electrically conductive paste, and each heat generating state was confirmed. The results are shown in Table 1.

  1 and 2 show a surface photograph and a heat distribution diagram of the heating element obtained in Example 3. FIG. As is apparent from the results of FIG. 2, heat was generated uniformly. In FIG. 2, the white region (the region that appears red in an actual color image) shows a high heat generation region, and in FIG. 2, the heat generation state is distributed substantially uniformly between the electrodes.

  3 and 4 show a surface photograph and a heat distribution diagram of the heating element obtained in Example 4. FIG. As is clear from the results of FIG. 4, white regions were distributed substantially uniformly between the electrodes, and heat was generated uniformly.

  5 and 6 show a surface photograph and a heat distribution diagram of the heating element obtained in Example 5. FIG. As is apparent from the results of FIG. 6, the white areas between the electrodes are unevenly distributed at both ends, the heat generation amount at both ends is large, and an inclined structure is shown.

  In the heating element obtained in Example 6, the band-shaped electrode portion has the first layer containing the metal-based conductive agent and the binder component as the surface layer and the second layer containing the carbon-based conductive agent and the binder component as the inner layer. Since it has a laminated structure, the wattage per unit area is large and the conductivity is improved.

Example 7
As shown in FIG. 7, a heat generating distribution diagram in which a sheet heating element is manufactured according to Examples 3 to 5 by combining a straight strip electrode portion and a curved strip electrode portion, and the heat generation state is observed by thermography. Is shown in FIG. As apparent from FIGS. 7 and 8, the planar heating element of the present invention can easily form electrodes having various shapes.

Comparative Example 2
Polyester conductive fibers coated with carbon nanotubes (“CNTEC240T48” manufactured by Kuraray Living Co., Ltd., 240 dtex, 1500 Ω / cm) are arranged on the weft, and polyester processed yarn (Kuraray Trading Co., Ltd., 167 dtex / 48 filament) is arranged on the warp. In addition, 16 first covering yarns, in which a copper fine wire having a diameter of 40 μm as an electrode is covered on a polyester processed yarn (167 dtex / 48 filament, manufactured by Kuraray Trading Co., Ltd.) as part of the warp yarns, are introduced in series. In the same manner, 16 second covering yarns are introduced to form a second belt-like portion so that a distance of 7 cm from the 16 introducing portions of the covering yarn is formed. 3rd and 4th belt-shaped parts are formed, and 3 steps of inter electrode width 7cm, 24cm long fabric Obtained.

When a DC current of 12 V was alternately applied to the copper thin wire of the electrode portion by plus and minus, it was confirmed that the copper thin wire portion locally generated heat although the heat generating portion (fabric portion) also generated heat. The wattage was 7 W, and the wattage per unit area was 410 W / m ² . FIG. 9 shows a heat distribution diagram by thermography of the obtained heating element, and shows the temperature distribution in the direction perpendicular to the length direction (AA ′ direction in FIG. 9) at the center in the length direction of the electrode portion. FIG. 10 shows a graph (vertical axis: temperature, horizontal axis: relative position between AA ′). As is clear from FIGS. 9 and 10, the heat generation part is uniform at about 33 ° C. at 20 ° C. room temperature, whereas the electrode part generates heat at about 47 ° C., and the distribution of the heat generation state is non-uniform. Met.

Example 8
A coating amount of 8 mg / cm ² of carbon-based conductive paste (“FC-415” manufactured by Fujikura Kasei Co., Ltd., carbon black paste) is applied to the band-shaped portion formed of the copper fine wire of the fabric obtained in Comparative Example 2. And then dried by screen printing.

When a DC current of 12 V was alternately applied to the electrode portion by plus and minus, a uniform heat generation state in which the heat generation portion did not generate heat locally was confirmed. The wattage was 7 W, and the wattage per unit area was 410 W / m ² . FIG. 11 shows a heat distribution diagram by thermography of the obtained heating element, and shows the temperature distribution in the direction perpendicular to the length direction (AA ′ direction in FIG. 11) at the center in the length direction of the electrode portion. FIG. 12 shows a graph (vertical axis: temperature, horizontal axis: relative position between AA ′). As is apparent from FIGS. 11 and 12, both the electrode part and the heat generating part generated heat of about 37 ° C. at 20 ° C. room temperature, and the distribution of the heat generating state was uniform.

  The planar heating element of the present invention is used in various fields, for example, outdoor equipment such as roads (for example, road heating, snow melting devices, anti-freezing devices, etc.), agricultural applications (for example, garden mats). Applications as building components (for example, anti-condensation and anti-fogging devices, floor heating, wall heating, etc.), applications as internal vehicle components (for example, trains, cars, etc., seats for aircraft, etc.) ), Clothing for cold protection (eg jackets, vests, rugs, bedding, shoes, warmers, hot carpets, etc.), furniture and daily use (eg chairs, foot warmers) Etc.).

Claims (20)

  A planar heating element formed by a heating part formed of a fiber structure containing conductive fibers and an electrode part for energizing the heating part, the electrode part containing a conductive agent and a binder component Planar heating element.   The planar heating element according to claim 1, wherein the electrode part is layered and at least a part thereof is impregnated in the fibrous structure of the heating part.   The planar heating element according to claim 1 or 2, wherein the planar shape of the electrode part is a curved line or strip.   The planar heating element according to any one of claims 1 to 3, wherein the fiber structure is a woven fabric.   The planar heating element according to claim 4, wherein the fiber structure further includes non-conductive fibers, and the conductive fibers are included in one of the warp and the weft.   The planar heating element according to claim 4 or 5, comprising a plurality of linear or strip electrode portions extending in a direction intersecting with the conductive fibers.   The planar heating element according to claim 6, wherein the distance between the strip electrode portions is uniform in the length direction of the electrode portions.   The planar heating element according to claim 6, wherein the distance between the strip electrode portions is non-uniform in the length direction of the electrode portions.   The planar heating element according to any one of claims 1 to 8, wherein the binder component is a cured resin.   The planar heating element according to claim 9, wherein the curable resin is a curable polyester resin.   The planar heating element according to any one of claims 1 to 10, wherein the conductive agent contains metal particles.   The planar heating element according to any one of claims 1 to 11, wherein the conductive agent contains carbonaceous particles.   The planar heating element according to any one of claims 1 to 12, wherein the electrode portion further includes a metal wire.   The planar heating element according to any one of claims 1 to 13, wherein the conductive fiber contains a carbon-based conductive agent.   The planar heating element according to claim 14, wherein the carbon-based conductive agent is a carbon nanotube.   The electrode part is a laminate formed of a first layer containing a metal-based conductive agent and a binder component, and a second layer laminated on the first layer and containing a carbon-based conductive agent and a binder component. The planar heating element according to any one of claims 2 to 15.   The manufacturing method of the planar heating element in any one of Claims 1-16 including the application | coating process which apply | coats the electrically conductive paste containing a electrically conductive agent and a binder component on the surface of a heat generating part.   The manufacturing method of Claim 17 including the hardening process which hardens the apply | coated electrically conductive paste.   The manufacturing method according to claim 17 or 18, wherein the conductive paste is applied by screen printing in the applying step.   An electrode used for an electrode part of a planar heating element formed by a heating part formed of a fiber structure containing conductive fibers and an electrode part for energizing the heating part, comprising a conductive agent and an adhesive Electrode for sheet heating element made of a conductive resin.