JP2008021545A - Planar heating element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planar heating element free from risk of a heating element and an insulating sheet part exfoliating at an adhesive interface even if expansion and contraction are repeated involving differences of degrees of the expansion and contraction due to bending or heat radiation at handling, especially, a planar heating element having flexibility. <P>SOLUTION: The planar heating element 1 is provided with an exothermic part 10, and sheet parts 20 covering the exothermic part 10. The exothermic part 10 consists of a thin-film heating element equipped with a plurality of through-holes, and the sheet parts 20 are arranged at a top face and a bottom face of the heating element 11 to cover the same 11, and are continued through the through-holes 111. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a planar heating element using a thin film heating element.

  In recent years, the use of planar heating elements has been promoted in the fields of civil engineering and architecture. For example, in the civil engineering field, application development is progressing particularly for roads, bridges, and pedestrian bridges for melting snow, and in the building field, it is used for floor heating, melting snow on the roof, and the like. In addition, the demand for sheet heating elements is expected to increase significantly in the future as home electronics or buildings become more intelligent.

  Conventionally, as a planar heating element, metal foil is bonded to a resin film, a predetermined heated portion is printed and etched and wired, and synthetic resin has carbon powder, carbon short fiber, aluminum powder, etc. Proposals have been proposed in which a filler is blended and formed into a sheet shape, a coating obtained by applying a conductive material such as carbon on a heat resistant fiber fabric such as glass fiber, and an electrode portion is attached (for example, Patent Document 1, Patent Document 2, Patent Document 3, and the like), electric heating carpets, water-freezing prevention, greenhouse heating, snow melting and the like.

These planar heating elements are bonded to an insulating sheet or board on both sides of a heating element such as a metal foil type, a metal powder paint type, a conductive filler kneading type such as carbon powder as described above, Or the method of integrally forming a heating element, an electrode part, and an insulating layer is generally adopted.
JP-A-5-299159 Japanese Patent Laid-Open No. 7-242827 JP-A-48-21230

  However, these planar heating elements have a structure in which an insulating sheet portion is adhered to both sides of the heating element to cover the heating element. Therefore, when a thin flexible sheet is used, Due to the repeated curvature, peeling is likely to occur at the adhesive interface between the heating element and the insulating sheet. In addition, since the heating element and the insulating sheet portion have different amounts of expansion and contraction due to heat generation, a phase difference occurs at the adhesive interface, but peeling is more likely to occur when this is repeated over a long period of use. In addition, when the heating element and the sheet portion are made of a material having poor adhesion, it is necessary to perform primer treatment or the like to improve the adhesion between the heating element and the covering sheet portion. Adhesiveness is a problem.

  In view of such a problem, the present invention provides the heating element and the insulating sheet portion even when the heating element and the insulating sheet portion are repeatedly expanded and contracted due to the difference in the degree of expansion and contraction between the heating element and the coating layer due to bending or heat generation during handling. It is an object of the present invention to provide a planar heating element that does not peel at the adhesive interface, particularly a flexible planar heating element.

  In the planar heating element formed by coating a thin sheet planar heating element with a sheet portion, the present invention forms a plurality of through holes in the planar heating element, and the sheet portion is formed by the through hole. As a result, it was found that peeling between the heating element and the sheet portion can be prevented by continuous integration, and the present invention has been completed.

  More specifically, the present invention provides the following.

  (1) A planar heating element comprising a heating part and a sheet part covering the heating part, wherein the heating part comprises a thin-film heating element having a plurality of through holes, and the sheet The sheet heating element is disposed on the upper and lower surfaces of the heating element, covers the heating element, and communicates with each other through the through hole.

  The planar heating element in the invention of (1) includes a heating part and a sheet part covering the heating part. Further, the heat generating part is formed of a thin film heat generating element, and the heat generating element has a plurality of through holes and is disposed on the upper surface and the lower surface of the heat generating element to cover the heat generating element. Since the sheet portion is continuous and integrated through the through-holes of the heating element, the adhesiveness between the heating element and the sheet portion is excellent, and the heating element and the sheet portion hardly peel off. Further, even if the heating element and the sheet portion are repeatedly expanded and contracted by repeated bending and bending operations or heating, there is no possibility that the heating element and the sheet portion are peeled off.

  (2) The sheet heating element according to (1), wherein the heating element is a metal foil having a thickness of 100 μm or less.

  In the planar heating element in the invention of (2), since the heating element is a thin metal foil having a thickness of 30 to 100 μm, the heating element has flexibility. By covering and using the sheet portion that can be flexibly deformed, a planar heating element having flexibility can be configured. By making the planar heating element deformable flexibly, for example, it can be configured so that it can be attached to an object having a curved surface or a moving object such as a human body.

  (3) The sheet heating element according to (1) or (2), wherein the sheet portion is formed of an insulating flexible material.

  In the sheet heating element according to the invention of (3), since the sheet portion is a flexible material having insulation properties, the sheet portion has flexibility. Combining the heating element, which is a metal foil having a thickness of 30 to 100 μm as described in (2) above, makes the sheet heating element flexible and flexible, so that the sheet heating element can be flexibly deformed. For example, it can be configured to be attachable to an object having a curved surface or a moving object such as a human body. Further, since the sheet portion itself has an insulating property, it is not necessary to coat the planar heating element with an insulating material, and therefore the sheet heating element can be suitably used even when the planar heating element is directly applied to a human body. It is also economical.

  (4) The planar heating element according to (3), wherein the flexible material is rubber or a thermoplastic resin.

  Since the sheet | seat part is the rubber | gum or thermoplastic resin which has insulation and flexibility, the planar heating element by invention of (4) is excellent in a softness | flexibility, and has insulation. Thereby, the planar heat generating body which can be used, such as being directly applied to a human body, can be comprised. Also, using rubber or a thermoplastic resin, covering the heat generating part with these, and heating them while pressing them, the rubber is heated and melted and vulcanized, and the thermoplastic resin is heated and melted, Rubber or thermoplastic resin disposed above and below the heating element is connected and integrated through a through hole formed in the heating element. Thereby, the adhesiveness of a heat generating element and a sheet | seat part improves more, and it becomes difficult to produce peeling.

  (5) A rubber or a thermoplastic resin is disposed on the upper and lower surfaces of the heat generating portion made of a thin film-shaped heat generating element having a plurality of through holes, and then subjected to a hot press treatment, and the rubber or the thermoplastic resin is A method for producing a planar heating element that is molded by vulcanization or melting.

(6) The method for producing a planar heating element according to (5), wherein the first-stage heat press treatment is performed at a temperature of 120 to 300 ° C. while pressing at a pressure of 50 to 250 Kg / cm ² .

  In the manufacturing method according to the inventions of (5) and (6), the upper and lower surfaces of the heat generating portion composed of a thin film heating element having a plurality of through holes are covered with rubber or thermoplastic resin, and this laminate is heated. By pressing, rubber or thermoplastic resin is vulcanized or melted to form a planar heating element. As a result, the rubber or thermoplastic resin is filled in the through hole formed in the heating element, so that the upper and lower rubbers or thermoplastic resin of the heating element are connected and integrated, and the Peeling is less likely to occur.

  According to the present invention, since the sheet portions covering the upper and lower surfaces of the heating element are continuously integrated by the through holes formed in the heating element, it is difficult to bond the heating element to the sheet portion. However, the high adhesive strength between the two can be obtained. Further, peeling due to repeated bending / bending operations and differences in expansion / contraction between the heating element and the sheet during heat generation is unlikely to occur.

  The present invention is applied to a planar heating element utilizing electric energy, and the upper and lower surfaces of a heating part composed of a thin film heating element having a plurality of through holes are covered with an insulating sheet part. And a sheet heating element in which the sheet portion is continuous through the through hole.

  The best mode for carrying out the present invention will be described below with reference to the drawings, but the present invention is not limited thereto.

  FIG. 1 is a plan view of an embodiment of the planar heating element of the present invention. 2 is a cross-sectional view taken along the line AA ′ in FIG.

  As shown in FIGS. 1 and 2, the sheet heating element 1 includes a heating part 10 and a sheet part 20 that covers the heating part 10.

  The heat generating part 10 is formed from a thin film-shaped heat generating element 11 in which a plurality of through holes 111 are formed, and power supply lines 12 a and 12 b connected to both ends of the heat generating element 11. Note that one end of each of the power supply lines 12a and 12b is connected to the end of the heating element 11 using a joining means such as solder or caulking (see an enlarged view of FIG. 2). Although not shown, a power terminal portion is provided at the other end of the power supply lines 12a and 12b, and power is supplied from the power terminal portion.

  Electric power is supplied to the heating element 11 via power supply lines 12a and 12b connected to both ends thereof. The heat generating element 11 constituting the heat generating part 10 generates heat by the supplied power. As a result, the entire sheet heating element 1 generates heat. Further, the heat generating portion 10 is covered with a sheet portion 20 having an insulating property, and preferably, the planar heat generating element 1 can be directly applied to a human body.

  The sheet unit 20 includes a first sheet 21 that covers the lower surface of the heat generating unit 10 and a second sheet 22 that covers the upper surface. The first sheet 21 and the second sheet 22 are formed in the heating element 11. They are connected and integrated by a through hole 111 (see an enlarged view of FIG. 2).

  In the present invention, power is supplied through the power supply lines 12 a and 12 b connected to both ends of the heating element 11 to generate heat. An electrode part may be disposed and connected, and a power supply line may be connected to the end of the electrode part. As a result, the current to the heating element 11 flows more uniformly over the entire area, which is more preferable because the entire planar area of the heating element 11 can be heated more uniformly. It is even more preferable that the electrode portions are connected across the entire width at both ends of the heating element 11.

  At this time, as an electrode material used for the electrode part, metals such as copper and nickel, which have a sufficiently low electric resistance value and are conventionally used as an electrode part, can be used. In addition, as the shape of the electrode portion, a fine metal fiber, a metal plated fiber for a synthetic fiber, or a conductive fiber such as a fiber containing a conductive material in a synthetic fiber, or a linear material such as a metal wire, these linear materials A wire mesh or cloth, a thin metal plate, or a metal foil can be used. In particular, conductive fibers and metal foils are preferably used because they are lightweight and flexible.

  Furthermore, it is particularly preferable to use a strip-like shape such as a metal foil ribbon because it can be easily connected over the entire width of both ends of the heating element 11 using a joining means such as seam welding or soldering. When this metal foil ribbon is used as an electrode portion, a copper or nickel foil ribbon having a low electric resistance value and a thickness of about 150 μm is preferable. In particular, the electric resistance value of these ribbons is 1 of the electric resistance value of the heating element. If it is / 10 or less, it is possible to allow a current to flow evenly over the entire width of the heating element 11 and to generate heat over the entire plane of the heating element 11.

  Hereinafter, various components in the above-described embodiment will be described.

[Heating element]
The heating element 11 used in the present invention includes a metal foil, a composite of conductive powder such as metal powder or carbon black and a matrix such as synthetic resin or rubber, carbon on a heat resistant fiber fabric such as glass fiber. Sheet material coated with a paint grafted with a conductive material such as metal fiber, carbon fiber, paper made of conductive fiber or mixed paper of several kinds of fibers including other insulating pulp, fiber, etc. Although it will not specifically limit if it exists, it is preferable that it is a sheet form in order to provide the flexibility of the planar heating element 1, and further, a thin-film metal foil is preferable from the workability of a through-hole.

  When a thin film-like metal foil is used as the heating element 11, examples of the metal foil include stainless steel such as austenitic stainless steel and ferritic stainless steel, nickel alloy such as nickel chrome alloy, aluminum, copper, and the like. A predetermined through hole is formed by punching the metal foil. By providing the through hole, the pattern is formed in a predetermined pattern so as to obtain a desired resistance value and heat generation amount. Moreover, the sheet | seat part 20 is integrated integrally so that it may mention later.

  The thickness of these metal foils can be appropriately determined depending on the use of the planar heating element, but is 100 μm or less, preferably about 3 to 100 μm, more preferably 30 to 100 μm.

  The shape of the through-hole 111 formed in the heating element 11 may be any of a circle, a square, a polygon, and the like, and the size and the number thereof are the size and thickness of the heating element 11 and the heating element 11. And appropriately determined from the adhesive force between the sheet portion 20 and the like. Note that the ratio of the total area of the through holes 111 to the area of the heating element 11 (also referred to as an opening ratio) is preferably 10 to 70%, and more preferably 30 to 60%. If the hole area ratio is within the above range, the sheet portion 20 is connected through the through hole 111 formed in the heating element 11 and has a preferable adhesive force. In addition, when heat is generated, local heat generation can be reduced.

  In addition, since the resistance value of the heat generating element 11 is increased by opening, increasing the opening ratio increases the resistance value and increases the amount of heat generation. Therefore, when designing the electrical characteristics of the heating element 11, it is preferable to consider the resistivity change due to the hole area ratio in addition to the material and shape (particularly the thickness) used as the heating element.

  The method of making holes in the heating element 11 varies depending on the material and properties of the heating element 11 to be used, but in the case of a flexible type or foil, it is generally performed by machining such as punching. In the case of a composite of conductive powder such as metal powder or carbon black and a matrix such as synthetic resin or rubber, the obtained composite may be machined as described above. It may be a method such as molding using a mold having a shape capable of forming a hole.

[Sheet part]
In this invention, the sheet | seat part 20 is formed with the raw material of the flexible material which has insulation and heat conductivity. Examples of such materials include natural rubber, isoprene rubber, polybutadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, ethylene-propylene rubber (EPDM, etc.), silicon rubber, fluorine rubber, acrylic rubber, urethane rubber, and thermoplastic elastomer. Various rubbers such as synthetic rubbers (polyolefin, polyester, polyamide elastomer, etc.), polyolefin resins such as polyethylene and polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene / vinyl alcohol copolymer Acrylic resin, polyethylene terephthalate, polybutylene terephthalate, polyester, mainly composed of coalesced polyacrylonitrile, polyamide, acrylic ester or methacrylic ester Polyesters such as polyalkylene naphthalate, polyacetals include thermoplastic resins such as cellulose derivatives of acetyl-di cellulose or acetyl tri cellulose.

  In the case of rubber, an unvulcanized material is used to coat the heat generating portion 10, and the sheet portion 20 covering the heat generating portion 10 generates heat by being heated and vulcanized while pressing. Since it is continuously integrated through the through-holes 111 formed in the body element 11, it is particularly preferable because the adhesion is further improved and peeling is less likely to occur.

[Production method]
The planar heating element 1 of the present invention is manufactured by covering the heat generating part 10 with the insulating sheet part 20. As a method of covering the heat generating part 10 with the sheet part 20, the sheet part 20 is configured. A flexible material is applied to the upper and lower surfaces of the heat generating portion 10 by a calendar molding method, a press molding method, or the like.

  For example, when the material is rubber, an unvulcanized rubber sheet is used, and the rubber sheet is arranged on the upper and lower surfaces so as to cover the heat generating portion 10, and this is incorporated into a rubber vulcanization molding die. Manufactured by heat pressing at high temperature and pressure in a vulcanizer. At this time, the vulcanization of the unvulcanized rubber sheet proceeds gradually, and the unvulcanized rubber sheets on the upper and lower surfaces facing each other cover the heating element 11 while flowing through the through-holes 111 and are integrally molded.

  Further, when the material is a thermoplastic resin, the thermoplastic resin is arranged on the upper and lower surfaces so as to cover the heat generating portion 10 as in the case of rubber, and this is incorporated into a press machine, and is manufactured by heat pressing. At this time, the thermoplastic resin is melted, and the thermoplastic resin on the upper and lower surfaces facing each other covers the heating element 11 and is integrated while flowing through the through hole 111.

  As a result, the through-hole 111 formed in the heating element 11 is filled with rubber or thermoplastic resin, and the opposing upper and lower rubber or thermoplastic resin is continuously integrated. Is more excellent, and peeling from the heat generating portion is less likely to occur.

As the conditions for the heat press treatment, in the case of an unvulcanized rubber sheet, it is appropriately selected depending on the type of rubber sheet to be used, but it is preferably a pressure of 50 to 250 Kg / cm ² , more preferably 100 to 200 Kg / cm ² . Is preferably processed at a temperature of 120 to 180 ° C., more preferably 140 to 160 ° C., preferably for 10 to 60 minutes, more preferably for 15 to 30 minutes. In the case of a thermoplastic resin, it is appropriately selected depending on the type of thermoplastic resin to be used, but preferably while pressing at a pressure of 50 to 250 Kg / cm ² , more preferably 100 to 200 Kg / cm ² , The treatment is performed at a temperature of 120 to 300 ° C., more preferably 140 to 180 ° C., preferably 10 to 60 minutes, more preferably 15 to 30 minutes.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

<Example 1>
A stainless steel foil with a circular shape and through-holes with a hole-to-hole distance of 4 mm and a radius of 1 mm was formed (opening ratio 40%). A metal foil with a width of 100 mm, a length of 300 mm, and a thickness of 50 μm was heated. A heating element was formed by connecting a power supply line to the substantially central part of both ends of the heating element with solder. An unvulcanized silicon rubber sheet having a width of 110 mm, a length of 310 mm, and a thickness of 1.0 mm was superimposed on the upper and lower surfaces of the heat generating portion. Next, the laminate of the heat generating portion and the rubber sheet was pressed at a pressure of 150 kg / cm ² and heated at a temperature of 150 ° C. for about 20 minutes to vulcanize the rubber sheet to have a width of 110 mm, a length of 310 mm, A planar heating element having a thickness of 2.0 mm was obtained. The obtained sheet heating element had a delamination strength of 20 kg / 25 mm.

  The five sheet heating elements obtained as described above were energized with an AC voltage of 100 V and the temperature was adjusted so that the surface temperature of the heating element was 280 ° C., and then for 2 hours, at room temperature for 2 hours. The heating cycle was repeated, and the durability of the planar heating element was observed. As a result, after 250 repetitions, no change in resistance value, breakage of metal, peeling between the rubber sheet and the heating element, and deformation were observed in any of the planar heating elements. Further, with respect to five sheet heating elements after the durability test, the withstand voltage performance was measured under the condition of 5000 V for 1 minute, but no dielectric breakdown occurred in any of the sheet heating elements. Furthermore, as a result of conducting a flexibility test on the five sheet heating elements, it was possible to bend to R3 mm.

<Comparative Example 1>
In Example 1, a stainless steel foil was not formed with a through hole, and the others were molded by the same method to obtain a planar heating element having a width of 110 mm, a length of 310 mm, and a thickness of 2.0 mm. The obtained sheet heating element had a delamination strength of 10 kg / 25 mm.

  For Comparative Example 1, the durability of the planar heating element was observed in the same manner as in Example 1. As a result, after 250 repetitions, changes in resistance value, breakage of metal, peeling of the rubber sheet and the heating element, and deformation were observed in any of the planar heating elements. In addition, with respect to five sheet heating elements after the durability test, the withstand voltage performance was measured in the same manner, but dielectric breakdown occurred in some sheet heating elements.

  From this result, it was confirmed that the planar heating element of the present invention was excellent in delamination strength and excellent in durability.

It is a top view of embodiment in the planar heat generating body of this invention. FIG. 2 is a cross-sectional view taken along line AA ′ in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Planar heating element 10 Heating part 11 Heating element 20 Sheet | seat part 111 Through-hole

Claims (6)

A sheet heating element comprising a heating part and a sheet part covering the heating part,
The heating part is composed of a thin-film heating element having a plurality of through holes,
The sheet heating element is a planar heating element that is disposed on an upper surface and a lower surface of the heating element, covers the heating element, and communicates with each other through the through hole. The planar heating element according to claim 1, wherein the heating element is a metal foil having a thickness of 100 μm or less.   The sheet heating element according to claim 1, wherein the sheet portion is formed of a flexible material having insulating properties.   The planar heating element according to claim 3, wherein the flexible material is rubber or a thermoplastic resin.   Rubber or thermoplastic resin is disposed on the upper and lower surfaces of the heat generating portion made of a thin film-shaped heating element having a plurality of through holes, and then subjected to heat press treatment to vulcanize or rub the rubber or thermoplastic resin. A method for producing a sheet heating element that is melted and molded. The method for producing a planar heating element according to claim 5, wherein the first heat press treatment is performed at a temperature of 120 to 300 ° C while pressing at a pressure of 50 to 250 Kg / cm ² .

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